CN115857055B - Vertical visibility calculation method based on numerical weather forecast - Google Patents
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Abstract
The invention belongs to the technical field of weather forecast, and discloses a vertical visibility calculation method based on numerical weather forecast, which comprises the following steps: selecting a membership function according to the established neural fuzzy model aiming at the first data information and the second data information of the monitoring point through the atmospheric haze prediction module, multiplying the first data information and the second data information to obtain third data information, calculating normalized credibility according to the third data information, and obtaining an atmospheric haze prediction result according to the fuzzy result, so that the instantaneity, the effectiveness and the accuracy of atmospheric haze prediction can be effectively improved; the system comprises: the system comprises an atmosphere data statistics module, a central control module, an atmosphere condition judging module, a cloud bottom height predicting module, an atmosphere haze predicting module, an atmosphere radiation calculating module, a visibility calculating module and a display module. Meanwhile, the accuracy of calculating the atmospheric vertical visibility can be greatly improved through the vertical visibility calculating module.
Description
Technical Field
The invention belongs to the technical field of weather forecast, and particularly relates to a vertical visibility calculation method based on numerical weather forecast.
Background
Visibility is classified into horizontal visibility, vertical visibility, and oblique visibility according to the observation direction. The vertical visibility refers to the maximum distance that a person with normal eyesight can recognize a black object vertically upwards (or downwards), and the maximum distance that a light with certain intensity can be seen and determined at night. The magnitude of the vertical visibility is mainly determined by two factors: ① The difference in brightness between the object and the background that sets off it. The larger (smaller) the difference, the larger (smaller) the visible distance. But this brightness difference typically does not vary much. ② Atmospheric transparency. The gas layer between the observer and the target can attenuate the aforementioned brightness difference. The worse (good) the atmospheric transparency, the smaller (large) the visible distance. The change in vertical visibility is largely dependent on the quality of the transparency of the atmosphere. And the weather phenomena such as fog, haze, smoke, dust, snow, rain and the like can cause the atmosphere to be turbid, so that the transparency is reduced. These weather phenomena are related to the aerosol particle number concentration and spectral distribution in the atmosphere. Scattered light generated by aerosol plasmids reduces the contrast of the brightness of the target to the background, limiting the visible distance.
Currently, the horizontal visibility is calculated mainly based on atmospheric aerosol parameters, and the ground visibility is calculated through parameters such as a ground extinction coefficient, an atmospheric aerosol optical thickness, a wavelength and the like. In numerical weather forecast, the liquid water content of the model forecast is often used for calculation. There is also a statistical prediction method for predicting fog based on basic weather factors such as atmospheric temperature, relative humidity, wind speed, etc., and further calculating the horizontal visibility. Since the atmospheric moisture content is not uniform in the vertical direction, the method for calculating the horizontal visibility is not applicable in the vertical direction. In atmospheric detection, a laser radar is often used to detect the cloud condition of the atmosphere and the inverted vertical extinction coefficient of the atmosphere to calculate the vertical visibility of the atmosphere. In numerical weather forecast, there are few numerical modes for calculating the vertical visibility, in some numerical forecast services requiring the vertical visibility, the vertical visibility is often calculated by combining a method of vertical integration of water vapor content with forecast of cloud and haze, but because the forecast of cloud and haze cannot be accurately forecast, comparison of a calculated result and observed data shows that the calculation of the vertical visibility is not accurate enough.
Through the above analysis, the problems and defects existing in the prior art are as follows:
(1) The existing vertical visibility calculation method based on numerical weather forecast cannot accurately predict atmospheric haze.
(2) The calculation of the atmospheric vertical visibility is inaccurate.
Disclosure of Invention
Aiming at the problems existing in the prior art, the invention provides a vertical visibility calculation method based on numerical weather forecast.
The invention is realized in such a way that the vertical visibility calculation method based on numerical weather forecast comprises the following steps:
step one, using a statistical program to count data such as atmospheric temperature, humidity, fog concentration, air pressure and the like through an atmospheric data statistics module;
step two, the central control module judges the atmospheric condition according to the counted atmospheric data by using a judging program through the atmospheric condition judging module;
Step three, predicting the cloud bottom height through a cloud bottom height prediction module; the atmospheric haze is predicted by using a prediction program through an atmospheric haze prediction module;
Calculating atmospheric radiation through an atmospheric radiation calculation module; calculating the vertical visibility of the atmosphere by a vertical visibility calculation module;
and fifthly, displaying the atmospheric temperature, the humidity, the cloud bottom height, the fog concentration, the judging result, the predicting result and the calculating result by using a display module.
The vertical visibility calculation method based on the numerical weather forecast comprises the following steps:
The system comprises an atmosphere data statistics module, a central control module, an atmosphere condition judging module, a cloud base height prediction module, an atmosphere haze prediction module, an atmosphere radiation calculation module, a vertical visibility calculation module and a display module;
The atmosphere data statistics module is connected with the central control module and is used for counting data such as atmosphere temperature, humidity, fog concentration, air pressure and the like through a statistics program;
The central control module is connected with the atmosphere data statistics module, the atmosphere condition judging module, the cloud bottom height predicting module, the atmosphere haze predicting module, the atmosphere radiation calculating module, the visibility calculating module and the display module and used for controlling the normal work of each module;
the atmosphere condition judging module is connected with the central control module and is used for judging the atmosphere condition according to the counted atmosphere data through a judging program;
the cloud bottom height prediction module is connected with the central control module and used for predicting the cloud bottom height through a prediction program;
The atmospheric haze prediction module is connected with the central control module and used for predicting atmospheric haze through a prediction program;
the atmospheric radiation calculation module is connected with the central control module and used for calculating atmospheric radiation;
the vertical visibility calculation module is connected with the central control module and used for calculating the vertical visibility of the atmosphere;
The display module is connected with the central control module and used for displaying the atmospheric temperature, the humidity, the cloud bottom height, the fog concentration, the judgment result, the prediction result and the calculation result through the display.
Further, the cloud bottom height prediction module predicts the following method:
(1) The clouds are divided into convection clouds and lamellar clouds, and the cloud bottom heights of the clouds are calculated respectively;
(2) The method for calculating the convection cloud base comprises the following steps: and establishing a statistical relationship between the water vapor content in the cloud and the atmospheric extinction coefficient, and calculating the cloud bottom height through the water vapor phase state and the water vapor content in the cloud. The specific method comprises the following steps: the cloud base height is calculated with the mixture ratio of the condensate, irrespective of the scattering and extinction of the aerosol, namely: Wherein 0.02 represents that the total transmittance of the atmosphere is 2%, β is an extinction coefficient, and Z c is a cloud base height (lifting condensation height). For cloud water, β=144.7ρ 0.88; for Yun Bing, β= 163.9 ρ 1.00, for raindrops, β=1.1 ρ 0.75; for snow, β=10.4ρ 0.78, where ρ is the water vapor density.
(3) The layered cloud base is mainly calculated through relative humidity, and the cloud base height is obtained according to an empirical formula when the relative humidity f is more than or equal to 87%.
Further, the atmospheric haze prediction module predicts the following steps:
(1) Constructing an atmosphere database, and storing atmosphere monitoring data into the atmosphere database; determining a monitoring point in an atmosphere monitoring area;
(2) Selecting a plurality of effective observation values as standards for predicting the atmospheric haze according to data information of monitoring points in the atmosphere monitoring area, and establishing a nerve fuzzy model, wherein the data information comprises first data information and second data information, and the nerve fuzzy model comprises an MLR model, an ANN model and an NF model;
(3) Selecting a membership function for the first data information and the second data information of each monitoring point, multiplying the first data information and the second data information to obtain third data information, and calculating normalized credibility according to the third data information; calculating a fuzzy result according to the fuzzy rule and the normalized credibility result of each monitoring point, and carrying out weighted average according to the fuzzy result to obtain an atmospheric haze prediction result.
Further, the monitoring points comprise environment evaluation points, comparison points, regional boundary points and traffic points.
Further, after the step of obtaining the atmospheric haze prediction result according to the fuzzy result, the atmospheric haze prediction method further includes:
Training the nerve fuzzy model according to a training sample set, and calculating an actual output result of the nerve fuzzy model;
Comparing the actual output result with the expected output result to obtain a verification result, and adjusting a parameter set of the neural fuzzy model according to the verification result, wherein the parameter set comprises a parameter set of a membership function and a result parameter set;
further, the training method includes a back propagation algorithm.
Further, the method for comparing the actual output result with the expected output result to obtain the verification result comprises the following steps:
And obtaining a verification result according to the prediction score and/or the hit rate which meet the index, the standard mean square error, the score deviation, the geometric mean deviation, the geometric variance and the observed value multiple difference.
Further, the atmospheric radiation calculation module calculates the following:
(A) Apparent brightness and large gas path scattered radiation
The result of the apparent brightness of the target and the background on the vertical non-uniform sight path can be obtained from the solving process of the atmospheric radiation transmission equation; the zenith angle cosine of the sun is-mu 0, and the azimuth angle is phi 0; the optical thickness of the top of the atmosphere is 0, and the optical thickness of the bottom (ground) of the atmosphere is τ 0; when the object is observed from the ground upwards, the object is positioned at the position with the optical thickness tau, the zenith angle cosine of the sight line direction of the observer is mu, the azimuth angle is phi, the zenith angle cosine of the light is-mu, and the azimuth angle is pi+phi; conversely, when the observer observes the object on the ground downwards from the position with the optical thickness tau, the zenith angle cosine of the observer's line of sight direction is-mu, the azimuth angle is pi+phi, and the zenith angle cosine of the light is mu, the azimuth angle is phi;
When the object located at the optical thickness τ is observed from the ground up, the object and the atmospheric background luminance are respectively transmitted vertically down to the observer, and as can be seen from the form solution of the radiation transmission equation, the apparent luminance I vis of the object itself reaching the observer and the atmospheric background luminance I b-v at the observer position are respectively:
wherein I path is the atmospheric scattered radiation on the line of sight optical path,
Similarly, when an object located on the ground is observed downward from the optical thickness τ, the object and the atmospheric background luminance are vertically transmitted upward to the observer, respectively, and as can be seen from the form solution of the radiation transmission equation, the apparent luminance I vis of the object itself reaching the observer and the atmospheric background luminance I b-v at the observer position are respectively:
Where I path is likewise the scattered radiation on the line of sight,
(B) Object background apparent contrast
According to the definition of the apparent contrast of the target background, the formulas (1), (2) and (3), (4) are respectively substituted into the following formulas,
CL＝(Ivis-Ib-v)/Ib-v (5)
The apparent contrast of the target background in the obliquely upward observation and the obliquely downward observation can be obtained:
The rules of the expression of the formulas (6) and (7) are completely consistent; it can be seen that the law of variation of the apparent contrast of the target background in the vertically non-uniform atmosphere is proportional to the ratio of the atmospheric background luminance I b-o at the target position and the atmospheric background luminance I b-v at the observer position, in addition to still adhering to the linear attenuation characteristic (proportional to the transmittance).
Further, the vertical visibility calculation module technology method is as follows:
1) Calculating the relation between the vertical observation distance and the apparent contrast of the target background;
From equations (6) and (7), the relationship between the vertical observation distance and the apparent contrast of the target background is:
Wherein β is the extinction coefficient, χ=i b-o/Ib-v;
considering an ideal black body on a white background, whose contrast is C 0 = -1, the visual distance V z corresponding to |c L |=ε is:
Standard atmospheric visibility V 2 and an atmospheric viewing distance R M corresponding to contrast thresholds of epsilon=0.02 and epsilon=0.05, respectively, can be obtained:
2) Calculating vertical visibility;
Namely vertical visibility: v 2 = f { β (l), χ } (11);
The method for calculating the ratio χ of the path distribution of the extinction coefficient β to the background brightness at the target position and at the observer position comprises the steps of:
(1.1) atmospheric background radiation calculation;
The atmospheric background radiation includes scattered solar radiation, atmospheric thermal radiation, and surface-emitted radiation; the long wave band (5-10000 μm) mainly considers the atmospheric heat radiation and the surface emission radiation; the short wave band (0.4-2 μm) mainly considers scattered solar radiation; atmospheric thermal radiation of 2-5 mu m, surface emission radiation and scattered solar radiation are all considered;
The radiation transmission equation considering absorption attenuation and emission enhancement of the gas layer is:
Wherein J λ (l) and I (l) are the scattered source function and the radiation intensity respectively;
Where P is the scattering phase function and J λ5 is the solar direct radiation; p (θ, Φ) =b (θ, Φ)/Q 5, B (θ, Φ) being the scattering function;
the radiation transmission equation is:
Different boundary conditions can be given according to different problems; for heat radiation, when the ground temperature is T s, the boundary conditions are:
Iλ(ut,μ)＝βλ(Ts)
Iλ(0,-μ)＝0,μ＝cosθ0 (14)
Defining the monochromatic atmospheric transmittance τ λ:
τ λ is the monochromatic transmittance of the atmosphere on the l path, and k eλ is the bulk attenuation coefficient;
And (3) carrying out multiple scattering treatment: solving a radiation transmission equation by using a modified accumulation method and using two-stream approximation;
The plane atmosphere basic monochromatic radiation transmission equation starts:
where u is the vertical optical thickness, μ is the cosine of the zenith angle of the path through which the light ray passes, Azimuth angle; the source function includes scattered solar radiation and thermal radiation:
Wherein J 0,Jms is a single scattering and multiple scattering source function respectively; boundary conditions:
ω0(u)＝Δus/Δu0
the surface assumes that the upward and downward radiant flux at τ and the upward radiance at the lower boundary are:
solving the general solution of the radiation transmission equation in the plane parallel atmosphere can obtain upward and downward radiance:
adopting two-stream approximation to the multiple scattering of the source function to obtain J, and substituting the J into the above formula to obtain the total irradiance distribution of the background or the target comprising the multiple scattering; the specific atmospheric background radiation calculation scheme is as follows:
(a) Scattered solar radiation
The calculation of scattered solar radiation (usually multiple scattering) adopts DISORT algorithm, but the algorithm has extremely slow calculation speed and is difficult to meet the engineering requirement; in order to solve the calculation speed problem, the following processing is adopted for the multiple scattering calculation: for the atmospheric radiation calculation of medium-high spectrum resolution, in a certain wavelength width range (such as a range of 500cm -1 of long-wave infrared rays, a range of -1 of visible light and thousands of cm near infrared rays, the ratio of the intensity of multiple scattered radiation to the earth surface albedo is in a monotone change trend after being ordered according to the optical thickness), only the scattering intensity direction distribution of a few wave number points needs to be accurately calculated, and spline interpolation is carried out at other wave number points according to the optical thickness of the atmosphere; during specific calculation, firstly, the wave band range to be calculated is divided into sections, the optical thickness of the atmosphere calculated by using a sunny radiation transmission mode is sequenced according to the size in each section, calculation points are selected on equal optical thickness logarithmic intervals, the direction distribution of the multiple scattering radiation intensity on the wave numbers corresponding to the points is calculated by DISORT, and the values on other wave numbers are obtained by fitting by using a spline method, so that a rapid algorithm of multiple scattering radiation transmission is realized;
(b) Atmospheric heat radiation
Atmospheric thermal radiation is a non-gray body radiation type, defined as the superposition of radiation per layer caused by temperature, expressed as follows:
Wherein: t i -the temperature of each layer of atmosphere;
Tau i -atmospheric transmittance up to each layer, which can be calculated from the atmospheric transmittance pattern described below; the upward and downward atmospheric heat radiation are different, and τ i in the formula is the transmittance of the atmosphere up to the i-th layer when calculating the downward atmospheric heat radiation; when the upward atmospheric heat radiation is calculated, τ i in the formula is the transmittance from the ground to the i layer; typically, when the wavelength is less than 2 μm, the heat radiation may be disregarded; in this band we first calculate the optical thickness of absorption and scattering of molecules from the atmosphere onto each layer using the atmospheric transmittance mode, the optical thickness of absorption and scattering of aerosols using the aerosol mode, then calculate the atmospheric thermal radiation according to equation (22) and the blackbody radiation formula;
(c) Surface emission radiation
The surface emission radiation is only related to the temperature of the surface, so that the surface emission radiation can be calculated by using a blackbody radiation formula
Iemis＝εB(Ts)τ (23)
Wherein:
t s -the temperature of the surface;
Tau-overall atmospheric transmittance;
Epsilon-emissivity, which can be obtained by using surface albedo: epsilon=1- ω;
the surface albedo value depends on the surface type;
(1.2) calculation of atmospheric transmittance
In the practical application of photoelectric engineering, a medium-low resolution photoelectric instrument is generally adopted; the atmospheric transmittance and the radiation quantity are accurately calculated by a line-by-line integration method (LBLRTM) and cannot be used because the calculated quantity is too large; therefore, the development of rapid medium-resolution atmospheric transmittance calculation software is required; the fast calculation mode of the absorption and transmittance of the atmospheric molecules is an important part of the fast radiation transmission mode;
The single-color atmospheric transmittance comprises single-color molecular absorption, molecular continuous absorption and scattering and aerosol attenuation;
(a) Atmospheric molecular absorption
The atmospheric height layer is divided into 50 layers: 0.0,1.0,2.0,3.0,4.0,5.0,6.0,7.0,8.0,9.0,10.0,11.0,12.0,13.0,14.0,15.0,16.0,17.0,18.0,19.0,20.0,21.0,22.0,23.0,24.0,25.0,27.5,30.0,32.5,35.0,37.5,40.0,42.5,45.0,47.5,50.0,55.0,60.0,65.0,70.0,75.0,80.0,85.0,90.0,95.0,100.0,105.0,110.0,115.0,120.0km; consider mainly that the absorption gas in the atmosphere comprises seven gas molecules of H 2O、CO2、O3、N2O、CO、CH4 and O 2;
the atmospheric molecular absorption transmittance is calculated by adopting an algorithm based on line-by-line integral fitting; the algorithm ensures the calculation accuracy and obviously improves the calculation speed; firstly, LBLRTM is used for calculating the monochromatic transmittance of seven absorption gases with different absorption contents under 9 reference air pressures and 9 reference temperatures, wherein the 9 reference air pressures are 1100hPa, 350hPa, 100hPa, 35hPa, 10hPa, 3.5hPa, 1hPa, 0.35hPa and 0.1hPa respectively; the 9 reference temperatures are 200K, 215K, 230K, 245K, 260K, 275K, 290K, 305K and 320K, respectively; these monochromatic transmittances are then averaged over a specified wavenumber interval (e.g., 1cm -1); fitting the calculated values at different absorption contents with a nonlinear fitting algorithm at each air pressure and temperature will result in a series of fitting coefficients, from which a database is built;
In the algorithm, t is reference temperature, p is reference air pressure, u is absorption content, c i (t, p) is a coefficient obtained by fitting at a certain reference temperature and reference air pressure, and M is the highest fitting times; if M takes 4, then 9×9×5=405 fitting coefficients will be obtained for each absorbing gas at each wavenumber;
for uniform path transmission, coefficients at any temperature and any air pressure can be interpolated, the temperature is linearly interpolated, when the temperature is less than 200K, the limit value of 200K is taken, and when the temperature is greater than 320K, the limit value of 320K is taken; the air pressure adopts logarithmic interpolation, when the air pressure is greater than 1100hPa, the limit value of 1100hPa is taken, and when the air pressure is less than 0.1hPa, the limit value of 0.1hPa is taken;
for non-uniform path transmission, the coefficients at each level are first obtained by interpolation, and then approximated by Curtis-Godson (C-G)
Obtaining the average coefficient on the path, and finally obtaining the average effective transmittance as follows
Wherein U is the total absorption content on the path;
U＝∫du(t，p) (27)
(b) Molecular continuous absorption and scattering
For molecular continuous absorption, mainly H 2O、CO2、O3、O2 and N 2 are active, and molecular scattering mainly considers rayleigh scattering; the continuous absorption and scattering of molecules is relatively simple compared with molecular absorption, and can be calculated by adopting the latest internationally recognized MT_CKD method;
(c) Aerosol attenuation (absorption and scattering)
The aerosol attenuation of arbitrary wavelength ground to a certain height H can be calculated according to the following formula
Wherein:
Beta (lambda, h) -the aerosol attenuation coefficient (sum of absorption coefficient and scattering coefficient) at any wavelength and at any height;
h-a transmission path;
Lambda-wavelength;
The aerosol attenuation coefficient at any wavelength and at any height consists of two parts:
β(λ，h)＝β(λ，0)×N(h) (29)
Wherein:
N (h) -aerosol attenuation profile height-dependent portion;
a spectrally varying portion of the aerosol attenuation coefficient of β (λ, 0) -ground;
the aerosol attenuation coefficient at a wavelength of 0.55 μm can be calculated from the ground visibility (vis) according to the following formula
Wherein, beta M is a molecular scattering coefficient of 0.55 mu m, and 0.00159km -1 can be approximately taken at sea level; there is a wavelength dependence of the extinction coefficient at 0.55 μm and the extinction coefficient at other wavelengths, depending on the extinction characteristics of the atmospheric molecules and aerosol particles at both wavelengths, i.e. the aerosol normalized extinction coefficient; normalized extinction coefficient and absorption coefficient and height distribution under different aerosol types, ground visibility and relative humidity are provided in MODTRAN; the corresponding normalized extinction coefficient beta 1 (lambda, 0) and the height distribution N (h) can be obtained by selecting the aerosol type, the given ground visibility and the relative humidity;
Then, the extinction coefficient of any wavelength near the ground is:
β(λ，0)＝β1(λ，0)·β(0.55，0) (31)
finally, the extinction coefficient of any wavelength and any height is ground extinction coefficient beta (lambda, 0) multiplied by height distribution N (h); the scattering coefficient and the absorption coefficient of any wavelength and any height can be obtained by the same method;
The total transmittance is the product of the transmittance of the individual factors:
Atmospheric extinction coefficient a:
Based on the method, the horizontal, vertical and inclined distribution of the atmospheric transmittance of infrared and visible light wave bands under the corresponding atmospheric condition is calculated, and the characteristics of the horizontal, vertical and inclined distribution of the atmospheric extinction coefficient and the transmittance under the influence of cloud and aerosol are emphasized.
In combination with the above technical solution and the technical problems to be solved, please analyze the following aspects to provide the following advantages and positive effects:
First, aiming at the technical problems in the prior art and the difficulty in solving the problems, the technical problems solved by the technical proposal of the invention are analyzed in detail and deeply by tightly combining the technical proposal to be protected, the results and data in the research and development process, and the like, and some technical effects brought after the problems are solved have creative technical effects. The specific description is as follows:
according to the invention, the atmospheric haze prediction module selects a membership function according to the first data information and the second data information of the established nerve fuzzy model aiming at the monitoring points, multiplies the first data information and the second data information to obtain third data information, calculates normalized credibility according to the third data information, calculates a fuzzy result according to a fuzzy rule and normalized credibility results of each monitoring point, and obtains an atmospheric haze prediction result according to the fuzzy result, so that the instantaneity, the effectiveness and the accuracy of atmospheric haze prediction can be effectively improved; meanwhile, the accuracy of calculating the vertical visibility of the atmosphere can be greatly improved through the vertical visibility calculation module.
Secondly, the technical scheme is regarded as a whole or from the perspective of products, and the technical scheme to be protected has the following technical effects and advantages:
according to the invention, the atmospheric haze prediction module selects a membership function according to the first data information and the second data information of the established nerve fuzzy model aiming at the monitoring points, multiplies the first data information and the second data information to obtain third data information, calculates normalized credibility according to the third data information, calculates a fuzzy result according to a fuzzy rule and normalized credibility results of each monitoring point, and obtains an atmospheric haze prediction result according to the fuzzy result, so that the instantaneity, the effectiveness and the accuracy of atmospheric haze prediction can be effectively improved; meanwhile, the accuracy of calculating the vertical visibility of the atmosphere can be greatly improved through the vertical visibility calculation module.
Drawings
Fig. 1 is a flowchart of a method for calculating vertical visibility based on numerical weather forecast according to an embodiment of the present invention.
Fig. 2 is a block diagram of a vertical visibility computing system based on numerical weather forecast according to an embodiment of the present invention.
Fig. 3 is a flowchart of a prediction method of an atmospheric haze prediction module provided by an embodiment of the present invention.
Figure 4 is a geometric schematic of the oblique line of sight visibility problem in a plane parallel atmosphere.
Fig. 5 is a flowchart of a calculation method of a vertical visibility calculation module according to an embodiment of the present invention.
FIG. 6 is a graph of a multiple scattering fast algorithm provided by an embodiment of the present invention.
In fig. 2: 1. an atmospheric data statistics module; 2. a central control module; 3. an atmospheric condition judgment module; 4. a cloud bottom height prediction module; 5. an atmospheric haze prediction module; 6. an atmospheric radiation calculation module; 7. a vertical visibility calculation module; 8. and a display module.
Detailed Description
The present invention will be described in further detail with reference to the following examples in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
1. The embodiments are explained. In order to fully understand how the invention may be embodied by those skilled in the art, this section is an illustrative embodiment in which the claims are presented for purposes of illustration.
As shown in fig. 1, the method for calculating the vertical visibility based on the numerical weather forecast provided by the invention comprises the following steps:
s101, using a statistical program to count data such as atmospheric temperature, humidity, fog concentration, air pressure and the like through an atmospheric data statistics module;
S102, the central control module judges the atmospheric condition according to the counted atmospheric data by using a judging program through the atmospheric condition judging module;
S103, predicting the cloud bottom height through a cloud bottom height prediction module; the atmospheric haze is predicted by using a prediction program through an atmospheric haze prediction module;
s104, calculating atmospheric radiation through an atmospheric radiation calculating module; calculating the vertical visibility of the atmosphere by a vertical visibility calculation module;
S105, displaying the atmospheric temperature, the humidity, the cloud bottom height, the fog concentration, the judgment result, the prediction result and the calculation result by using a display module.
According to the invention, the atmospheric haze prediction module selects a membership function according to the first data information and the second data information of the established nerve fuzzy model aiming at the monitoring points, multiplies the first data information and the second data information to obtain third data information, calculates normalized credibility according to the third data information, calculates a fuzzy result according to a fuzzy rule and normalized credibility results of each monitoring point, and obtains an atmospheric haze prediction result according to the fuzzy result, so that the instantaneity, the effectiveness and the accuracy of atmospheric haze prediction can be effectively improved; meanwhile, the accuracy of calculating the vertical visibility of the atmosphere can be greatly improved through the vertical visibility calculation module.
As shown in fig. 2, the vertical visibility computing system based on numerical weather forecast according to the embodiment of the present invention includes: the system comprises an atmosphere data statistics module 1, a central control module 2, an atmosphere condition judging module 3, a cloud bottom height predicting module 4, an atmosphere haze predicting module 5, an atmosphere radiation calculating module 6, a vertical visibility calculating module 7 and a display module 8;
The atmosphere data statistics module 1 is connected with the central control module 2 and is used for counting data such as atmosphere temperature, humidity, fog concentration, air pressure and the like through a statistics program;
the central control module 2 is connected with the atmosphere data statistics module 1, the atmosphere condition judging module 3, the cloud bottom height predicting module 4, the atmosphere haze predicting module 5, the atmosphere radiation calculating module 6, the vertical visibility calculating module 7 and the display module 8 and is used for controlling the normal work of each module;
the atmospheric condition judging module 3 is connected with the central control module 2 and is used for judging the atmospheric condition according to the counted atmospheric data through a judging program;
The cloud bottom height prediction module 4 is connected with the central control module 2 and is used for predicting the cloud bottom height through a prediction program;
the atmospheric haze prediction module 5 is connected with the central control module 2 and is used for predicting atmospheric haze through a prediction program;
the atmospheric radiation calculation module 6 is connected with the central control module 2 and is used for calculating atmospheric radiation;
The vertical visibility calculation module 7 is connected with the central control module 2 and is used for calculating the vertical visibility of the atmosphere;
and the display module is connected with the central control module 2 and is used for displaying the atmospheric temperature, the humidity, the cloud bottom height, the fog concentration, the judgment result, the prediction result and the calculation result through a display.
According to the invention, the atmospheric haze prediction module selects a membership function according to the first data information and the second data information of the established nerve fuzzy model aiming at the monitoring points, multiplies the first data information and the second data information to obtain third data information, calculates normalized credibility according to the third data information, calculates a fuzzy result according to a fuzzy rule and normalized credibility results of each monitoring point, and obtains an atmospheric haze prediction result according to the fuzzy result, so that the instantaneity, the effectiveness and the accuracy of atmospheric haze prediction can be effectively improved; meanwhile, the accuracy of calculating the vertical visibility of the atmosphere can be greatly improved through the vertical visibility calculation module.
The prediction method of the cloud bottom height prediction module provided by the invention comprises the following steps:
(1) The clouds are divided into convection clouds and lamellar clouds, and the cloud bottom heights of the clouds are calculated respectively;
(2) The method for calculating the convection cloud base comprises the following steps: and establishing a statistical relationship between the water vapor content in the cloud and the atmospheric extinction coefficient, and calculating the cloud bottom height through the water vapor phase state and the water vapor content in the cloud. The specific method comprises the following steps: the cloud base height is calculated with the mixture ratio of the condensate, irrespective of the scattering and extinction of the aerosol, namely: Wherein 0.02 represents that the total transmittance of the atmosphere is 2%, β is an extinction coefficient, and Z c is a cloud base height (lifting condensation height). For cloud water, β=144.7ρ 0.88; for Yun Bing, β= 163.9 ρ 1.00, for raindrops, β=1.1 ρ 0.75; for snow, β=10.4ρ 0.78, where ρ is the water vapor density.
(3) The layered cloud base is mainly calculated through relative humidity, and the cloud base height is obtained according to an empirical formula when the relative humidity f is more than or equal to 87%.
As shown in fig. 3, the prediction method of the atmospheric haze prediction module provided by the invention is as follows:
S201, constructing an atmosphere database, and storing atmosphere monitoring data into the atmosphere database; determining a monitoring point in an atmosphere monitoring area;
s202, selecting a plurality of effective observation values as standards for predicting atmospheric haze according to data information of monitoring points in the atmosphere monitoring area, and establishing a nerve fuzzy model, wherein the data information comprises first data information and second data information, and the nerve fuzzy model comprises an MLR model, an ANN model and an NF model;
S203, selecting a membership function for the first data information and the second data information of each monitoring point, multiplying the first data information and the second data information to obtain third data information, and calculating normalized credibility according to the third data information; calculating a fuzzy result according to the fuzzy rule and the normalized credibility result of each monitoring point, and carrying out weighted average according to the fuzzy result to obtain an atmospheric haze prediction result.
According to the invention, the atmospheric haze prediction module selects the membership function according to the first data information and the second data information of the established nerve fuzzy model aiming at the monitoring points, multiplies the first data information and the second data information to obtain third data information, calculates the normalized credibility according to the third data information, calculates the fuzzy result according to the fuzzy rule and the normalized credibility result of each monitoring point, and obtains the atmospheric haze prediction result according to the fuzzy result, so that the instantaneity, the effectiveness and the accuracy of atmospheric haze prediction can be effectively improved.
The monitoring points provided by the invention comprise environment evaluation points, comparison points, regional boundary points and traffic points.
After the step of obtaining the atmospheric haze prediction result according to the fuzzy result, the atmospheric haze prediction method provided by the invention further comprises the following steps:
Training the nerve fuzzy model according to a training sample set, and calculating an actual output result of the nerve fuzzy model;
and comparing the actual output result with the expected output result to obtain a verification result, and adjusting a parameter set of the neural fuzzy model according to the verification result, wherein the parameter set comprises a parameter set of a membership function and a result parameter set.
The training method provided by the invention comprises a back propagation algorithm.
The method for comparing the actual output result with the expected output result to obtain the verification result comprises the following steps:
And obtaining a verification result according to the prediction score and/or the hit rate which meet the index, the standard mean square error, the score deviation, the geometric mean deviation, the geometric variance and the observed value multiple difference.
The calculation method of the atmospheric radiation calculation module provided by the invention comprises the following steps:
As shown in fig. 4, (a) apparent brightness and large gas path scattered radiation
The result of the apparent brightness of the target and the background on the vertical non-uniform sight path can be obtained from the solving process of the atmospheric radiation transmission equation; the zenith angle cosine of the sun is-mu 0, and the azimuth angle is phi 0; the optical thickness of the top of the atmosphere is 0, and the optical thickness of the bottom (ground) of the atmosphere is τ 0; when the object is observed from the ground upwards, the object is positioned at the position with the optical thickness tau, the zenith angle cosine of the sight line direction of the observer is mu, the azimuth angle is phi, the zenith angle cosine of the light is-mu, and the azimuth angle is pi+phi; conversely, when the observer observes the object on the ground downwards from the position with the optical thickness tau, the zenith angle cosine of the observer's line of sight direction is-mu, the azimuth angle is pi+phi, and the zenith angle cosine of the light is mu, the azimuth angle is phi;
When the object located at the optical thickness τ is observed from the ground up, the object and the atmospheric background luminance are respectively transmitted vertically down to the observer, and as can be seen from the form solution of the radiation transmission equation, the apparent luminance I vis of the object itself reaching the observer and the atmospheric background luminance I b-v at the observer position are respectively:
wherein I path is the atmospheric scattered radiation on the line of sight optical path,
Similarly, when an object located on the ground is observed downward from the optical thickness τ, the object and the atmospheric background luminance are vertically transmitted upward to the observer, respectively, and as can be seen from the form solution of the radiation transmission equation, the apparent luminance I vis of the object itself reaching the observer and the atmospheric background luminance I b-v at the observer position are respectively:
Where I path is likewise the scattered radiation on the line of sight,
(B) Object background apparent contrast
According to the definition of the apparent contrast of the target background, the formulas (1), (2) and (3), (4) are respectively substituted into the following formulas,
CL＝(Ivis-Ib-v)/Ib-v (5)
The apparent contrast of the target background in the obliquely upward observation and the obliquely downward observation can be obtained:
The rules of the expression of the formulas (6) and (7) are completely consistent; it can be seen that the law of variation of the apparent contrast of the target background in the vertically non-uniform atmosphere is proportional to the ratio of the atmospheric background luminance I b-o at the target position and the atmospheric background luminance I b-v at the observer position, in addition to still adhering to the linear attenuation characteristic (proportional to the transmittance).
As shown in fig. 5, the technical method of the vertical visibility calculation module provided by the invention is as follows:
s301, calculating the relation between the vertical observation distance and the apparent contrast of the target background;
From equations (6) and (7), the relationship between the vertical observation distance and the apparent contrast of the target background is:
Wherein β is the extinction coefficient, χ=i b-o/Ib-v;
considering an ideal black body on a white background, whose contrast is C 0 = -1, the visual distance V z corresponding to |c L |=ε is:
Standard atmospheric visibility V 2 and an atmospheric viewing distance R M corresponding to contrast thresholds of epsilon=0.02 and epsilon=0.05, respectively, can be obtained:
s302, calculating vertical visibility;
Namely vertical visibility: v 2 = f { β (l), χ } (11);
According to the invention, the accuracy of calculating the vertical visibility of the atmosphere can be greatly improved through the vertical visibility calculating module.
The method for calculating the ratio χ of the path distribution of the extinction coefficient β to the background brightness at the target position and at the observer position comprises the steps of:
(1.1) atmospheric background radiation calculation;
The atmospheric background radiation includes scattered solar radiation, atmospheric thermal radiation, and surface-emitted radiation; the long wave band (5-10000 μm) mainly considers the atmospheric heat radiation and the surface emission radiation; the short wave band (0.4-2 μm) mainly considers scattered solar radiation; atmospheric thermal radiation of 2-5 mu m, surface emission radiation and scattered solar radiation are all considered;
The radiation transmission equation considering absorption attenuation and emission enhancement of the gas layer is:
Wherein J λ (l) and I (l) are the scattered source function and the radiation intensity respectively;
where P is the scattering phase function and J λ5 is the solar direct radiation; p (θ, Φ) =b (θ, Φ)/Q s, B (θ, Φ) being the scattering function;
the radiation transmission equation is:
Different boundary conditions can be given according to different problems; for heat radiation, when the ground temperature is T s, the boundary conditions are:
Iλ(ut,μ)＝βλ(Ts)
Iλ(0,-μ)＝0,μ＝cosθ0 (14)
Defining the monochromatic atmospheric transmittance τ λ:
τ λ is the monochromatic transmittance of the atmosphere on the l path, and k eλ is the bulk attenuation coefficient;
And (3) carrying out multiple scattering treatment: solving a radiation transmission equation by using a modified accumulation method and using two-stream approximation;
The plane atmosphere basic monochromatic radiation transmission equation starts:
where u is the vertical optical thickness, μ is the cosine of the zenith angle of the path through which the light ray passes, Azimuth angle; the source function includes scattered solar radiation and thermal radiation:
Wherein J 0,Jms is a single scattering and multiple scattering source function respectively; boundary conditions:
ω0(u)＝Δus/Δu0
the surface assumes that the upward and downward radiant flux at τ and the upward radiance at the lower boundary are:
solving the general solution of the radiation transmission equation in the plane parallel atmosphere can obtain upward and downward radiance:
adopting two-stream approximation to the multiple scattering of the source function to obtain J, and substituting the J into the above formula to obtain the total irradiance distribution of the background or the target comprising the multiple scattering; the specific atmospheric background radiation calculation scheme is as follows:
(a) Scattered solar radiation
The calculation of scattered solar radiation (usually multiple scattering) adopts DISORT algorithm, but the algorithm has extremely slow calculation speed and is difficult to meet the engineering requirement; in order to solve the calculation speed problem, the following processing is adopted for the multiple scattering calculation: for the atmospheric radiation calculation of medium-high spectrum resolution, in a certain wavelength width range (such as a range of 500cm -1 of long-wave infrared rays, a range of visible light and a range of thousands cm -1 of near infrared rays, as shown in fig. 6, the ratio of the intensity of multiple scattered radiation to the earth surface albedo is in a monotone change trend after being ordered according to the optical thickness), only the scattering intensity direction distribution of few wavenumber points (such as 8 red x numbers in fig. 6) needs to be accurately calculated, and spline interpolation is carried out on other wavenumber points according to the optical thickness of the atmosphere; during specific calculation, firstly, the wave band range to be calculated is divided into sections, the optical thickness of the atmosphere calculated by using a sunny radiation transmission mode is sequenced according to the size in each section, calculation points are selected on equal optical thickness logarithmic intervals, the direction distribution of the multiple scattering radiation intensity on the wave numbers corresponding to the points is calculated by DISORT, and the values on other wave numbers are obtained by fitting by using a spline method, so that a rapid algorithm of multiple scattering radiation transmission is realized;
(b) Atmospheric heat radiation
Atmospheric thermal radiation is a non-gray body radiation type, defined as the superposition of radiation per layer caused by temperature, expressed as follows:
Wherein: t i -the temperature of each layer of atmosphere;
Tau i -atmospheric transmittance up to each layer, which can be calculated from the atmospheric transmittance pattern described below; the upward and downward atmospheric heat radiation are different, and τ i in the formula is the transmittance of the atmosphere up to the i-th layer when calculating the downward atmospheric heat radiation; when the upward atmospheric heat radiation is calculated, τ i in the formula is the transmittance from the ground to the i layer; typically, when the wavelength is less than 2 μm, the heat radiation may be disregarded; in this band we first calculate the optical thickness of absorption and scattering of molecules from the atmosphere onto each layer using the atmospheric transmittance mode, the optical thickness of absorption and scattering of aerosols using the aerosol mode, then calculate the atmospheric thermal radiation according to equation (22) and the blackbody radiation formula;
(c) Surface emission radiation
The surface emission radiation is only related to the temperature of the surface, so that the surface emission radiation can be calculated by using a blackbody radiation formula
Iemis＝εB(Ts)τ (23)
Wherein:
t s -the temperature of the surface;
Tau-overall atmospheric transmittance;
Epsilon-emissivity, which can be obtained by using surface albedo: epsilon=1- ω;
the surface albedo value depends on the surface type;
(1.2) calculation of atmospheric transmittance
In the practical application of photoelectric engineering, a medium-low resolution photoelectric instrument is generally adopted; the atmospheric transmittance and the radiation quantity are accurately calculated by a line-by-line integration method (LBLRTM) and cannot be used because the calculated quantity is too large; therefore, the development of rapid medium-resolution atmospheric transmittance calculation software is required; the fast calculation mode of the absorption and transmittance of the atmospheric molecules is an important part of the fast radiation transmission mode;
The single-color atmospheric transmittance comprises single-color molecular absorption, molecular continuous absorption and scattering and aerosol attenuation;
(a) Atmospheric molecular absorption
The atmospheric height layer is divided into 50 layers: 0.0,1.0,2.0,3.0,4.0,5.0,6.0,7.0,8.0,9.0,10.0,11.0,12.0,13.0,14.0,15.0,16.0,17.0,18.0,19.0,20.0,21.0,22.0,23.0,24.0,25.0,27.5,30.0,32.5,35.0,37.5,40.0,42.5,45.0,47.5,50.0,55.0,60.0,65.0,70.0,75.0,80.0,85.0,90.0,95.0,100.0,105.0,110.0,115.0,120.0km; consider mainly that the absorption gas in the atmosphere comprises seven gas molecules of H 2O、CO2、O3、N2O、CO、CH4 and O 2;
the atmospheric molecular absorption transmittance is calculated by adopting an algorithm based on line-by-line integral fitting; the algorithm ensures the calculation accuracy and obviously improves the calculation speed; firstly, LBLRTM is used for calculating the monochromatic transmittance of seven absorption gases with different absorption contents under 9 reference air pressures and 9 reference temperatures, wherein the 9 reference air pressures are 1100hPa, 350hPa, 100hPa, 35hPa, 10hPa, 3.5hPa, 1hPa, 0.35hPa and 0.1hPa respectively; the 9 reference temperatures are 200K, 215K, 230K, 245K, 260K, 275K, 290K, 305K and 320K, respectively; these monochromatic transmittances are then averaged over a specified wavenumber interval (e.g., 1cm -1); fitting the calculated values at different absorption contents with a nonlinear fitting algorithm at each air pressure and temperature will result in a series of fitting coefficients, from which a database is built;
In the algorithm, t is reference temperature, p is reference air pressure, u is absorption content, c i (t, p) is a coefficient obtained by fitting at a certain reference temperature and reference air pressure, and M is the highest fitting times; if M takes 4, then 9×9×5=405 fitting coefficients will be obtained for each absorbing gas at each wavenumber;
for uniform path transmission, coefficients at any temperature and any air pressure can be interpolated, the temperature is linearly interpolated, when the temperature is less than 200K, the limit value of 200K is taken, and when the temperature is greater than 320K, the limit value of 320K is taken; the air pressure adopts logarithmic interpolation, when the air pressure is greater than 1100hPa, the limit value of 1100hPa is taken, and when the air pressure is less than 0.1hPa, the limit value of 0.1hPa is taken;
for non-uniform path transmission, the coefficients at each level are first obtained by interpolation, and then approximated by Curtis-Godson (C-G)
Obtaining the average coefficient on the path, and finally obtaining the average effective transmittance as follows
Wherein U is the total absorption content on the path;
U＝∫du(t，p) (27)
(b) Molecular continuous absorption and scattering
For molecular continuous absorption, mainly H 2O、CO2、O3、O2 and N 2 are active, and molecular scattering mainly considers rayleigh scattering; the continuous absorption and scattering of molecules is relatively simple compared with molecular absorption, and can be calculated by adopting the latest internationally recognized MT_CKD method;
(c) Aerosol attenuation (absorption and scattering)
The aerosol attenuation of arbitrary wavelength ground to a certain height H can be calculated according to the following formula
Wherein:
Beta (lambda, h) -aerosol attenuation coefficient (sum of absorption coefficient and scattering coefficient) at any wavelength and at any height;
h-a transmission path;
Lambda-wavelength;
The aerosol attenuation coefficient at any wavelength and at any height consists of two parts:
β(λ，h)＝β(λ，0)×N(h) (29)
Wherein:
N (h) -aerosol attenuation profile height-dependent portion;
a spectrally varying portion of the aerosol attenuation coefficient of β (λ, 0) -ground;
the aerosol attenuation coefficient at a wavelength of 0.55 μm can be calculated from the ground visibility (vis) according to the following formula
Wherein, beta M is a molecular scattering coefficient of 0.55 mu m, and 0.00159km -1 can be approximately taken at sea level; there is a wavelength dependence of the extinction coefficient at 0.55 μm and the extinction coefficient at other wavelengths, depending on the extinction characteristics of the atmospheric molecules and aerosol particles at both wavelengths, i.e. the aerosol normalized extinction coefficient; normalized extinction coefficient and absorption coefficient and height distribution under different aerosol types, ground visibility and relative humidity are provided in MODTRAN; the corresponding normalized extinction coefficient beta 1 (lambda, 0) and the height distribution N (h) can be obtained by selecting the aerosol type, the given ground visibility and the relative humidity;
Then, the extinction coefficient of any wavelength near the ground is:
β(λ，0)＝β1(λ，0)·β(0.55，0) (31)
finally, the extinction coefficient of any wavelength and any height is ground extinction coefficient beta (lambda, 0) multiplied by height distribution N (h); the scattering coefficient and the absorption coefficient of any wavelength and any height can be obtained by the same method;
The total transmittance is the product of the transmittance of the individual factors:
Atmospheric extinction coefficient a:
Based on the method, the horizontal, vertical and inclined distribution of the atmospheric transmittance of infrared and visible light wave bands under the corresponding atmospheric condition is calculated, and the characteristics of the horizontal, vertical and inclined distribution of the atmospheric extinction coefficient and the transmittance under the influence of cloud and aerosol are emphasized.
2. Application example. In order to prove the inventive and technical value of the technical solution of the present invention, this section is an application example on specific products or related technologies of the claim technical solution.
According to the invention, the atmospheric haze prediction module selects a membership function according to the first data information and the second data information of the established nerve fuzzy model aiming at the monitoring points, multiplies the first data information and the second data information to obtain third data information, calculates normalized credibility according to the third data information, calculates a fuzzy result according to a fuzzy rule and normalized credibility results of each monitoring point, and obtains an atmospheric haze prediction result according to the fuzzy result, so that the instantaneity, the effectiveness and the accuracy of atmospheric haze prediction can be effectively improved; meanwhile, the accuracy of calculating the vertical visibility of the atmosphere can be greatly improved through the vertical visibility calculation module.
It should be noted that the embodiments of the present invention can be realized in hardware, software, or a combination of software and hardware. The hardware portion may be implemented using dedicated logic; the software portions may be stored in a memory and executed by a suitable instruction execution system, such as a microprocessor or special purpose design hardware. Those of ordinary skill in the art will appreciate that the apparatus and methods described above may be implemented using computer executable instructions and/or embodied in processor control code, such as provided on a carrier medium such as a magnetic disk, CD or DVD-ROM, a programmable memory such as read only memory (firmware), or a data carrier such as an optical or electronic signal carrier. The device of the present invention and its modules may be implemented by hardware circuitry, such as very large scale integrated circuits or gate arrays, semiconductors such as logic chips, transistors, etc., or programmable hardware devices such as field programmable gate arrays, programmable logic devices, etc., as well as software executed by various types of processors, or by a combination of the above hardware circuitry and software, such as firmware.
3. Evidence of the effect of the examples. The embodiment of the invention has a great advantage in the research and development or use process, and has the following description in combination with data, charts and the like of the test process.
According to the invention, the atmospheric haze prediction module selects a membership function according to the first data information and the second data information of the established nerve fuzzy model aiming at the monitoring points, multiplies the first data information and the second data information to obtain third data information, calculates normalized credibility according to the third data information, calculates a fuzzy result according to a fuzzy rule and normalized credibility results of each monitoring point, and obtains an atmospheric haze prediction result according to the fuzzy result, so that the instantaneity, the effectiveness and the accuracy of atmospheric haze prediction can be effectively improved; meanwhile, the accuracy of calculating the vertical visibility of the atmosphere can be greatly improved through the vertical visibility calculation module.
The foregoing is merely illustrative of specific embodiments of the present invention, and the scope of the invention is not limited thereto, but any modifications, equivalents, improvements and alternatives falling within the spirit and principles of the present invention will be apparent to those skilled in the art within the scope of the present invention.
Claims (8)
1. The vertical visibility calculating method based on the numerical weather forecast is characterized by comprising the following steps of:
step one, using a statistical program to count the data of the atmospheric temperature, the humidity, the fog concentration and the air pressure through an atmospheric data statistics module;
step two, the central control module judges the atmospheric condition according to the counted atmospheric data by using a judging program through the atmospheric condition judging module;
Step three, predicting the cloud bottom height through a cloud bottom height prediction module; the atmospheric haze is predicted by using a prediction program through an atmospheric haze prediction module;
Calculating atmospheric radiation through an atmospheric radiation calculation module; calculating the vertical visibility of the atmosphere by a vertical visibility calculation module;
Displaying the atmospheric temperature, the humidity, the cloud bottom height, the fog concentration, the judgment result, the prediction result and the calculation result by using a display module through a display;
the atmospheric haze prediction module predicts the following steps:
(1) Constructing an atmosphere database, and storing atmosphere monitoring data into the atmosphere database; determining a monitoring point in an atmosphere monitoring area;
(2) Selecting a plurality of effective observation values as standards for predicting the atmospheric haze according to data information of monitoring points in the atmosphere monitoring area, and establishing a nerve fuzzy model, wherein the data information comprises first data information and second data information, and the nerve fuzzy model comprises an MLR model, an ANN model and an NF model;
(3) Selecting a membership function for the first data information and the second data information of each monitoring point, multiplying the first data information and the second data information to obtain third data information, and calculating normalized credibility according to the third data information; calculating a fuzzy result according to the fuzzy rule and the normalized credibility result of each monitoring point, and carrying out weighted average according to the fuzzy result to obtain an atmospheric haze prediction result;
the vertical visibility calculation module comprises the following technical steps:
1) Calculating the relation between the vertical observation distance and the apparent contrast of the target background;
the relationship between the vertical observation distance and the apparent contrast of the target background is as follows:
wherein β is the extinction coefficient, χ=i b-o/Lb-v;
Considering an ideal black body on a white background, whose contrast is C 0 = -1, the visual distance V τ corresponding to |c L |=ε is:
standard atmospheric visibility V 2 and the meteorological viewing distance R M are obtained corresponding to contrast thresholds epsilon=0.02 and epsilon=0.05, respectively:
2) Calculating vertical visibility;
namely vertical visibility: v 2 = f { β (l), χ }.
2. The method for calculating the vertical visibility based on the numerical weather forecast according to claim 1, wherein the method for predicting the cloud base height by the prediction module is as follows:
(1) The clouds are divided into convection clouds and lamellar clouds, and the cloud bottom heights of the clouds are calculated respectively;
(2) The method for calculating the convection cloud base comprises the following steps: establishing a statistical relationship between the water vapor content in the cloud and an atmospheric extinction coefficient, and calculating the cloud bottom height by calculating the water vapor phase state and the water vapor content in the cloud;
(3) The layered cloud base is mainly calculated through relative humidity, and the cloud base height is obtained according to an empirical formula when the relative humidity f is more than or equal to 87%.
3. The method for calculating the vertical visibility based on the numerical weather forecast according to claim 1, wherein the monitoring points include an environmental evaluation point, a comparison point, a regional boundary point and a traffic point.
4. The method for calculating vertical visibility based on numerical weather forecast according to claim 1, wherein after the step of obtaining an atmospheric haze prediction result from the blurred result, the atmospheric haze prediction method further comprises:
Training the nerve fuzzy model according to a training sample set, and calculating an actual output result of the nerve fuzzy model;
and comparing the actual output result with the expected output result to obtain a verification result, and adjusting a parameter set of the neural fuzzy model according to the verification result, wherein the parameter set comprises a parameter set of a membership function and a result parameter set.
5. The method for calculating vertical visibility based on numerical weather forecast of claim 4, wherein said training method includes a back propagation algorithm.
6. The method for calculating vertical visibility based on numerical weather forecast according to claim 4, wherein the method for comparing the actual output result with the expected output result to obtain the verification result includes:
And obtaining a verification result according to the prediction score and/or the hit rate which meet the index, the standard mean square error, the score deviation, the geometric mean deviation, the geometric variance and the observed value multiple difference.
7. The method for calculating the vertical visibility based on the numerical weather forecast according to claim 1, wherein the atmospheric radiation calculating module calculates the vertical visibility based on the numerical weather forecast by the following method:
(A) Apparent brightness and large gas path scattered radiation
The result of the apparent brightness of the target and the background on the vertical non-uniform sight path can be obtained from the solving process of the atmospheric radiation transmission equation; the zenith angle cosine of the sun is-mu 0, and the azimuth angle isThe optical thickness of the top of the atmosphere is 0, and the optical thickness of the bottom of the atmosphere is tau 0; when viewed from the ground, the target is positioned at an optical thickness τ, the zenith angle cosine of the observer's line of sight is μ, and the azimuth angle isWhereas the zenith angle cosine of the light is-mu and the azimuth angle isConversely, when the observer observes the object located on the ground from a position where the optical thickness is τ, the zenith angle cosine of the observer's line of sight direction is- μ, and the azimuth angle isWhereas the zenith angle cosine of the light is mu and the azimuth angle is
When the object positioned at the optical thickness tau is observed from the ground upwards, the object and the atmospheric background brightness are respectively transmitted to the observer vertically downwards, and the object brightness reaches the apparent brightness L vis of the observer and the atmospheric background brightness I b-v at the position of the observer as known from the form solution of the radiation transmission equation;
Likewise, when an object located on the ground is observed downwards from the optical thickness τ, the object and the atmospheric background luminance are respectively transmitted vertically upwards to the observer, and as can be seen from the form solution of the radiation transmission equation, the object's own luminance reaches the observer's apparent luminance L vis and the atmospheric background luminance I b-v at the observer's position;
(B) Object background apparent contrast
And according to the definition of the apparent contrast of the target background, obtaining the apparent contrast of the target background when the target background is observed obliquely upwards and observed obliquely downwards.
8. A numerical weather forecast-based vertical visibility computing system implementing the numerical weather forecast-based vertical visibility computing method of any one of claims 1-7, characterized in that the numerical weather forecast-based vertical visibility computing system includes:
The atmosphere data statistics module is connected with the central control module and is used for counting the data of the atmosphere temperature, the humidity, the fog concentration and the air pressure through a statistics program;
The central control module is connected with the atmosphere data statistics module, the atmosphere condition judging module, the atmosphere haze prediction module, the atmosphere radiation calculation module, the visibility calculation module and the display module and used for controlling the normal work of each module;
the atmosphere condition judging module is connected with the central control module and is used for judging the atmosphere condition according to the counted atmosphere data through a judging program;
the cloud bottom height prediction module is connected with the central control module and used for predicting the cloud bottom height through a prediction program;
The atmospheric haze prediction module is connected with the central control module and used for predicting atmospheric haze through a prediction program;
the atmospheric radiation calculation module is connected with the central control module and used for calculating atmospheric radiation;
the vertical visibility calculation module is connected with the central control module and used for calculating the vertical visibility of the atmosphere;
The display module is connected with the central control module and used for displaying the atmospheric temperature, the humidity, the cloud bottom height, the fog concentration, the judgment result, the prediction result and the calculation result through the display.
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| CN106526710A (en) * | 2016-10-19 | 2017-03-22 | 陈文飞 | Haze prediction method and device |
| CN110471131A (en) * | 2019-08-16 | 2019-11-19 | 中国海洋大学 | The fining atmospheric horizontal visibility automatic forecast method and system of high spatial resolution |
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