CN115034035A - Multi-pollutant cross-boundary transmission flux quantification integration technology and transmission channel identification method - Google Patents
Multi-pollutant cross-boundary transmission flux quantification integration technology and transmission channel identification method Download PDFInfo
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Abstract
The invention discloses a multi-pollutant cross-boundary transmission flux quantification integration technology and a transmission channel identification method; the invention adopts a method of three-dimensional observation and model simulation mutual authentication, quantitatively reveals the trans-boundary transmission rule of various atmospheric pollutants aiming at different situations (fixed point, navigation, trans-boundary and the like), and realizes the direct comparison and verification of transmission quantitative simulation and observation results; and further identifying a main transmission channel polluted by the atmosphere in the target area based on a cross-boundary transmission flux quantification result of the atmospheric pollutants. The method has the advantages that the method can quantitatively reveal the pollution cross-border transmission rule between cities and counties, and solves the problem of division of air pollution responsibility.
Description
Technical Field
The invention relates to the technical fields of stereo observation, model simulation, multi-pollutant cross-boundary transmission flux quantitative calculation, atmospheric pollution transmission channel identification and the like, in particular to a multi-pollutant cross-boundary transmission flux quantitative integration technology and a transmission channel identification method.
Background
In recent years, the atmospheric environmental pollution integrally presents' coexistence of multiple pollution problems, superposition of multiple pollution sources and multi-scale relationUnion, multi-process coupling and multi-medium influence. By PM 2.5 And O 3 The problem of regional composite air pollution characterized by pollution is increasingly prominent, and the regional composite air pollution causes wide attention of researchers at home and abroad. Under the influence of atmospheric circulation, PM 2.5 Long transmission distance, wide influence range and remarkable transboundary conveying characteristics, which can cause PM in a connected area 2.5 The concentration is increased, and the phenomena of heavy pollution such as dust haze and photochemical pollution frequently occur, so that great threats are caused to the quality and visibility of atmospheric environment, climate change, human health and national economic development. Multiple studies show that the current urban atmospheric pollution has the characteristic of multi-scale composite pollution, namely, the current urban atmospheric pollution is evolved into urban scale pollution through the processes of point, line and surface mixing, pollution diffusion and chemical conversion of cities, wherein the small-scale and local pollution is caused by the emission of a single pollution source; under a specific geographic environment and a certain atmosphere circulation background, other areas are influenced by middle and long distance transportation of city-crossing, province-crossing, region-crossing and the like, and finally regional composite pollution is developed. Therefore, how to solve the problem of cross-boundary transportation of atmospheric pollutants among cities, provinces and regions and quantitatively identify the cross-boundary transmission rule of the pollutants is an urgent necessity for effectively improving regional air quality and realizing joint defense and joint control of regional atmospheric pollution.
At present, the technical methods widely used for carrying out the analysis research on the space source of pollutants are mainly divided into the following methods: backward track model, air pollution observation and mathematical statistics method, air quality model method, etc. The backward trajectory model (HYSPLIT-4) can simulate the transportation, diffusion and sedimentation processes of various pollutants more completely, and is widely applied to the research of atmospheric pollution transportation. However, the backward trajectory model does not consider the chemical reaction process of the pollutants in the transmission process, and has obvious deviation on the estimation of the transmission distance when the simulation trajectory runs, so that the transmission contributions of different regions to the target region cannot be quantitatively identified. The potential source contribution factor method (PSCF) and the concentration trace weighting method (CWT) require long-term continuous observations, the observation sites cannot represent the entire city or area, and the set thresholds can be significantly subjective. Monitoring with various contaminantsThe device is used for carrying out space three-dimensional real-time online observation on regional multi-scale atmospheric pollutants, acquiring the spatial distribution and transmission path of the pollutants by using observation data, and effectively identifying the rule and the characteristic of mutual transmission of the pollutants in different regions. Common observation equipment comprises laser radar stereo observation, laser radar navigation observation, a multi-axis differential absorption spectrum online monitoring system (MAX-DOAS) and the like. The air quality model method comprehensively utilizes the air pollution source discharge list data and the simulated meteorological background field data, and simulates the processes of transmission, chemical conversion, diffusion, sedimentation and the like of the air pollutants such as gas, aerosol and the like in the atmosphere by using a three-dimensional numerical method, so that the contribution conditions of the pollution sources in different areas and a plurality of discharge sources to the concentration of various pollutants at a receptor site can be quantitatively estimated, and the method is one of the most extensive and important means for studying the multi-scale pollution transmission problem by scholars at home and abroad at present. At present, mainstream air quality models include CMAQ, CAMx, WRF-Chem, NAQPMS and the like, and based on the models, the pollution contributions of different source regions to receptor point positions and receptor cities can be simulated and obtained, and a transmission contribution matrix of near-ground pollutants across regions and cities is established. However, how to quantitatively calculate the cross-boundary conveying amount of the adjacent boundary according to the conveying conditions of various pollutants between adjacent areas with different heights in the vertical direction, between adjacent cities, between adjacent counties and between adjacent roads and roads still needs to be deeply researched at present. Meanwhile, various pollutants (such as atmospheric particulate matters PM with aerodynamic equivalent diameter less than or equal to 2.5 mu m) obtained based on a model at present 2.5 、O 3 Etc.) can be quantitatively simulated and analyzed, and the pollution transmission contribution of a certain city, a certain area to a certain receptor point, a certain city and a certain area can be quantitatively simulated and analyzed. However, model simulation has certain uncertainty, a certain deviation can be generated between the model simulation and an actual observed value, and most of the current transmission quantification methods are used for verifying the simulated pollutant concentration, so that the accuracy of a pollution transmission quantification result obtained by simulation is indirectly proved; and the transmitted analog data cannot be directly verified by transmitting the monitoring data. In addition, the technical method for identifying the polluted transmission channel based on the pollutant cross-boundary transmission flux also comprisesIt is not yet mature.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide a multi-pollutant cross-boundary transmission flux quantification integration technology and a transmission channel identification method, which have important significance for solving the cross-boundary conveying problem among adjacent regions, adjacent cities, adjacent counties and adjacent roads and accurately disclosing the cross-boundary conveying quantification rule of atmospheric pollutants. Meanwhile, scientific and technological support can be provided for solving the problems of mutual transmission and responsibility division of atmospheric pollution between adjacent cities.
The technical scheme of the invention is specifically introduced as follows.
The invention provides a multi-pollutant cross-boundary transmission flux quantitative integration technical method based on mutual evidence of observation and simulation, which is characterized in that a fixed-point transmission flux observed value and a simulated value of a pollutant are respectively obtained based on laser radar fixed-point observation and a WRF-CAMx three-dimensional numerical model, and then model parameters are adjusted by analyzing the accuracy of simulation result verification so as to optimize the WRF-CAMx three-dimensional numerical model and improve the model simulation accuracy; wherein:
when a fixed-point transmission flux observation value of a pollutant is obtained by laser radar fixed-point observation, online observation is carried out on the basis of the laser radar and a wind profiler, and the vertical distribution of the transmission flux of the atmospheric pollutant at different heights of an observation station is obtained by combining a three-dimensional distribution structure of the mass concentration of the atmospheric pollutant obtained by two devices with three-dimensional wind field data; the fixed-point transmission flux observation value is the product of the monitored mass concentration and the wind vector of the atmospheric pollutants;
when a WRF-CAMx three-dimensional numerical model is used for simulating and obtaining a fixed-point transmission flux simulation value, because the model belongs to an Euler three-dimensional grid model, a target area is regarded as a three-dimensional box body formed by a plurality of grids, each grid has a fixed three-dimensional space coordinate, and meteorological elements and atmospheric pollutant concentrations of each grid in a research area are respectively provided; in order to obtain wind direction, wind speed and concentration information of atmospheric pollutants corresponding to the same height above the ground of each grid, and to facilitate comparison and verification with transmission flux stereo observation data, WRF and CAMx are set to be the same vertical layer number and delta coordinate parameters, wherein the delta coordinate parameter is a coordinate parameter defined for setting the height of each vertical layer in the vertical direction in a WRF meteorological model, the value range of the delta coordinate parameter is [0-1], and the WRF meteorological model automatically sets the height of each vertical layer according to the set delta coordinate parameter; the fixed-point transmission flux analog value is the product of pollutant analog mass concentration and analog wind vector, wherein the pollutant analog mass concentration is obtained through CAMx air quality model simulation, and the analog wind vector comprises wind direction and wind speed and is obtained through WRF meteorological model simulation.
In the invention, an observed value and a simulated value of the navigation transmission flux of pollutants are respectively obtained based on laser radar navigation observation and WRF-CAMx three-dimensional numerical model simulation, and then model parameters are adjusted by analyzing the accuracy of simulation result verification so as to optimize the WRF-CAMx three-dimensional numerical model and improve the model simulation accuracy; wherein:
when the laser radar sailing observation obtains a sailing transmission flux observation value of pollutants, the vertical distribution of the transmission flux of the atmospheric pollutants at different ground heights on a closed-loop monitoring path is obtained by combining three-dimensional wind field information and an included angle between a vehicle driving azimuth and a wind direction based on a three-dimensional distribution result of the mass concentration of the atmospheric pollutants obtained by the laser radar through closed-loop sailing observation; the calculation formula of the observed value of the navigation transmission flux is as follows:
Flux(z)＝C P (z)×V(z)×sinθ
in the formula:
flux (z) -transport flux of atmospheric pollutants at height z from the ground in units: μ g.m -2 ·s -1 ；
C P (z) -mass concentration of atmospheric pollutants at height z from the ground in units: μ g m -2 ·s -1 ；
V (z) -observed wind speed at height z from ground in units: m/s;
sin theta is the included angle between the driving azimuth angle of the vehicle and the wind direction recorded by the GPS;
and when the sailing transmission flux analog value is calculated, comparing and verifying the specific point position concerned in sailing observation and the specific grid point position flux analog value simulated by the WRF-CAMx model, namely, the sailing transmission flux analog value is the product of the pollutant analog concentration and the analog wind vector.
In the invention, an observed value and a simulated value of the cross-boundary transmission flux of the pollutant are respectively obtained based on high-altitude meteorological-near-ground pollutant observation and WRF-CAMx three-dimensional numerical model simulation, and then model parameters are adjusted by analyzing the accuracy of simulation result verification so as to optimize the WRF-CAMx three-dimensional numerical model and improve the model simulation accuracy;
when cross-boundary transmission flux observed values of atmospheric pollutants in a target area and adjacent areas around the target area are calculated, the atmospheric pollutant monitoring concentrations and wind vector observed values of the target area and the adjacent areas around the target area are considered; for the atmospheric pollutant monitoring concentration, point-by-point analysis is carried out by an assumed method, the near-ground atmospheric pollutant concentration obtained by near-ground conventional atmospheric pollutant monitoring equipment in the point position monitoring of a target area represents the concentration of the atmospheric pollutant of the whole target area, the pollution concentration is uniformly distributed in the vertical direction, the atmospheric pollutant concentration of the near-ground of adjacent areas is obtained by downloading through an air quality website and is also used as the integral concentration of each adjacent area, and the concentration is uniformly distributed in the vertical direction; for the observed value of the wind vector, the wind vector at the border between the target area and each adjacent area is assumed to be consistent, that is, the wind speed and the wind direction of the target area and each adjacent area are obtained by adopting a wind speed and a wind direction value based on a wind profiler erected on the target area; on the basis, calculating a cross-boundary transmission flux observed value between the target region and each adjacent region; the calculation formula of the cross-boundary transmission flux observed value is as follows:
Flux u ＝Σ h L·H k ·c up ·u·8.64×10 -8
Flux v ＝Σ h L·H k ·c up ·v·8.64×10 -8
in the formula: flux u -transport flux of contaminants in east-west direction, unit: t/d;
Flux v -transport flux of contaminants in north-south direction, unit: t/d;
h-the vertical highest layer observed by the wind profiler, unit: m;
l-the length of the boundary line where two adjacent regions contact, unit: m;
H k -height resolution in the vertical direction of the wind profiler, unit: m;
C up -mass concentration of atmospheric pollutants in upwind cities in units: mu g/m 3 ；
u-wind speed in the east-west direction, unit: m/s;
v-wind speed in the north-south direction, in units: m/s.
A method for simulating the cross-boundary transmission flux of various atmospheric pollutants based on a WRF-CAMx three-dimensional numerical model is as follows: firstly, selecting a target area, dividing a boundary line of atmospheric pollution trans-boundary transmission according to an administrative boundary line method, determining each adjacent area bordering the target area, and dividing a simulation range into different grids for simulating and calculating the trans-boundary transmission flux of the atmospheric pollution through gridding division in a model;
the target area is regarded as a three-dimensional box body formed by a plurality of grids, a certain vertical section in the box body is selected, the product of the flow velocity of each infinitesimal element on the section, the concentration of the atmospheric pollutants and the area is calculated, and then the integral is carried out on the whole section, so that the mass of the atmospheric pollutants passing through the whole section in unit time is obtained;
the WRF-CAMx mode belongs to an Euler three-dimensional grid mode, each grid has a fixed three-dimensional space coordinate, and meteorological elements and atmospheric pollutant concentrations of each grid in a research area are respectively provided; in addition, the WRF and the CAMx are set to be the same as the vertical layer number and the delta coordinate parameters, so that the corresponding information of wind direction, wind speed and atmospheric pollutant concentration at the same height above the ground of each grid can be obtained; in conclusion, the cross section to be calculated is discretized according to the mesh division mode in the WRF and CAMx modes, and the cross-boundary transmission flux of the atmospheric pollutants on the specific cross section is calculated by using the output data of the two modes, wherein the specific calculation formula is as follows:
in the formula: flux-atmospheric pollutants transport Flux across boundaries, unit: t/d;
h-vertical highest layer of model setup, unit: m;
l-the boundary line of two adjacent areas, in units: m;
l-simulation grid resolution, unit: km;
H k -simulating the height difference between the vertical layers k and k + 1;
c-mass concentration of atmospheric pollutants, unit: mu g/m 3 ；
v-wind direction and speed, unit: DEG and m/s;
n-normal vector through vertical section, dimensionless;
based on a cross-boundary transmission flux calculation formula, respectively calculating inflow fluxes and outflow fluxes of atmospheric pollutants at different ground heights from a single box body, a plurality of box bodies at the same ground height on a boundary line to all box bodies in the vertical direction by taking the inflow target area of the atmospheric pollutants as positive and the outflow target area as negative; the net flux refers to the vector sum of the inflow and outflow fluxes of atmospheric pollutants, where positive values represent the net inflow flux and negative values represent the net outflow flux.
In the WRF-CAMx three-dimensional numerical model, the number of vertical layers of WRF and CAMx is set to be 28.
In the invention, by introducing a correlation coefficient COR, a normalized average deviation NMB and a normalized average error NME statistical index, the observed value and the simulated value of the transmission flux of the pollutant are compared and verified, and the verification accuracy of the simulated result is analyzed.
The invention also provides a method for identifying the pollution transmission channel based on the pollutant cross-boundary transmission flux, which comprises the following steps:
based on an optimized WRF-CAMx three-dimensional numerical model, inflow flux, outflow flux and net flux of atmospheric pollutants between each city and the adjacent periphery in a research area are obtained through simulation, and according to the inflow and outflow directions of the atmospheric pollutants of each target city, all the inflow and outflow directions of the cities in the target area are combed and integrated, so that the integral inflow and outflow directions of the atmospheric pollutants in the area are obtained, and a transmission channel in the target area is identified.
Compared with the prior art, the invention has the beneficial effects that:
(1) by means of two technical methods of stereo observation and model simulation, the quantitative problem of the trans-boundary transmission of various pollutants under different conditions (fixed point, navigation and trans-boundary) is solved by accurately disclosing the quantitative rules of fixed point transmission flux, navigation transmission flux and trans-boundary transmission flux, identifying the evolution characteristics of inflow flux, outflow flux and net flux among regions, cities, counties, towns/streets and solving the problem of multi-scale (region, city, towns/streets) atmospheric pollution responsibility division.
(2) By adopting a method of mutual authentication of stereo observation and model simulation, the fixed point transmission flux, the navigation transmission flux and the cross-boundary transmission flux obtained by observation are compared and verified with the simulation value of the corresponding transmission flux, so that the limitation that the verification simulation accuracy only depends on the verification of meteorological parameters and pollutant concentration parameters is broken through, the direct comparison analysis of the simulation result of transmission quantification and the observation result is realized, and the simulation error range is determined; on the other hand, the model can be optimized and checked through comparing the verification result, and the purpose of improving the simulation accuracy of the model is achieved through various methods such as adjusting the simulation parameters of the model, optimizing the simulation scheme, perfecting the emission list of the atmospheric pollution source and the like.
(3) Based on the quantitative simulation of the trans-boundary transmission flux of various atmospheric pollutants, the inflow flux, the outflow flux and the net flux of each trans-boundary of various atmospheric pollutants in the range of a target area are identified, and then main transmission channels of various atmospheric pollutants in the target area are determined, so that effective scientific and technological support is provided for the joint defense and joint control of the area and the emergency treatment of heavy pollution.
Drawings
Fig. 1 is an example of a three-dimensional box.
FIG. 2 is PM 2.5 And comparing the transmission flux analog value with the observed value.
FIG. 3 shows selection of key point positions and PM of sailing observation flux 2.5 A vertical distribution of flux was observed.
FIG. 4 shows six-ring PM of Beijing 2.5 The vertical distribution of the sailing simulation flux.
Fig. 5 is a schematic diagram of adjacent inter-zone boundary line identification.
FIG. 6 is a unit area infinitesimal vector schematic.
Fig. 7 is a schematic diagram of the inflow flux and the outflow flux of the atmospheric pollutants in the vertical section of a single box body.
Fig. 8 is a vertical cross-sectional view of the discretized border line of the adjacent regions.
FIG. 9 is a geographic location distribution of the cis and peripheral neighbors/cities.
FIG. 10 is a schematic view of PM in different seasons and surrounding counties 2.5 The perpendicular distribution of the net flux analog values to the observed values.
FIG. 11 shows PM of Jingjin Ji area 2.5 Contaminating the main transport channels.
Detailed Description
The technical solution of the present invention will be described in detail with reference to the accompanying drawings and embodiments.
The invention establishes a multi-pollutant cross-boundary transmission flux quantitative integration technology and a transmission channel identification method based on a WRF-CAMx model, wherein the embodiment mainly adopts PM of Jingjin Ji area 2.5 Atmospheric pollution transmission is an example. Except for Jingjin Ji area and PM 2.5 The method is also applicable to any other area and other atmospheric pollutants (such as O) 3 And atmospheric particulate matter PM having an aerodynamic equivalent diameter of 10 μm or less 10 、CO、SO 2 Nitrogen oxides NOx, volatile organic compounds VOCs, and the like).
The invention aims to provide a multi-pollutant cross-boundary transmission flux quantification integration technology and a transmission channel identification method, aiming at multi-pollutant cross-boundary transmission under different conditions and introducing 3 statistical indexes such as correlation Coefficient (COR), normalized mean deviation (NMB) and Normalized Mean Error (NME) to compare and verify an analog value and an observed value based on technical means such as meteorological radar observation, laser radar stereo observation and meteorological and air quality model (WRF-CAMx). Wherein the multiple scenarios include 3 cases, detailed as follows: case 1: a fixed-point transmission flux calculation method based on mutual verification of laser radar fixed-point observation and model simulation. Case 2: a method for calculating the sailing transmission flux based on mutual verification of laser radar sailing observation and model simulation. Case 3: a cross-boundary transmission flux calculation method based on mutual verification of high altitude weather-pollutant observation and model simulation.
The WRF-CAMx model refers to a coupled three-dimensional numerical model constructed by a meteorological model WRF and an air quality model CAMx, wherein the meteorological model WRF can provide simulation values of wind vectors (wind direction and wind speed), and the air quality model CAMx can provide concentrations of various atmospheric pollutants. Because the two models are three-dimensional numerical models, the wind vectors and the concentration values of the atmospheric pollutants at different heights in the vertical direction of the gridding target area can be simulated. In order to obtain wind direction, wind speed and concentration information of atmospheric pollutants corresponding to the same height above the ground of each grid and facilitate comparison and verification with transmission flux stereo observation data, WRF and CAMx are set to be the same vertical layer number (28 layers) and delta coordinate parameters, wherein the vertical layer number refers to the number of layers divided in the vertical direction, each vertical layer corresponds to different heights, the delta coordinate parameter is a coordinate parameter defined for setting the height of each vertical layer in the vertical direction in a WRF meteorological model, the value range of the delta coordinate parameter is [0-1], and the WRF meteorological model can automatically set the height of each vertical layer according to the set delta coordinate parameter.
Model-based acquisition of PM for evaluation 2.5 The accuracy of a cross-boundary transmission flux simulation result introduces 3 statistical indexes such as a correlation Coefficient (COR), a normalized mean deviation (NMB) and a Normalized Mean Error (NME), and the calculation formula is as follows:
in the formula: sim (i) And Obs (i) The simulated and observed values represent the cross-boundary transmitted flux (including the incoming flux, the outgoing flux and the net flux), respectively, and n represents the number of samples.
Case 1: a fixed-point transmission flux calculation method based on mutual verification of laser radar fixed-point observation and model simulation.
The fixed point transmission flux refers to the mass of atmospheric pollutants passing through a unit area per unit time.
Wherein,
(1) the principle of acquiring the pollutant transmission flux by laser radar fixed-point observation is based on online observation of a laser radar and a wind profiler, and the vertical distribution of the pollutant transmission flux at different heights of an observation site can be obtained by combining a three-dimensional distribution structure of the atmospheric pollutant mass concentration obtained by two devices with three-dimensional wind field data. The calculation formula is the product of the pollutant concentration and the wind speed, namely:
FLUX NSh ＝C ph ×V NSh
FLUX EWh ＝C ph ×V EWh
in the formula:
FLUX NSh -the observed value of the fixed point transmission flux of the atmospheric pollutants with the height h meters above the ground in the south and north directions and the unit of the observed value is mu g.m -2 ·s -1 (ii) a When FLUX NSh When the value is positive, it is defined as the input of atmospheric pollutants from south to north, when FLUX NSh When the value is negative, the atmospheric pollutants are output from north to south;
FLUX EWh -the observed value of the fixed-point transmission flux of the atmospheric pollutants with the height h meters above the ground in the east-west direction is in units of mu g.m -2 ·s -1 (ii) a When FLUX EWh When the value is positive, it is defined that the atmospheric pollutant is input from west to east, when FLUX EWh When the value is negative, the atmospheric pollutants are defined to be output from east to west;
C Ph atmospheric pollutants (e.g. O) at a height h meters above the ground 3 、PM 2.5 Etc.) in units of μ g/m 3 ；
V NSh -the observed value of the wind vector in the south-north direction at the height h m from the ground is m/s when V NSh When the value is positive, the wind direction is south wind, and when V is positive NSh When the value is negative, the wind direction is north wind.
V EWh -the observed value of the wind vector in the east-west direction at the height h m from the ground in m/s when V EWh When the value is positive, the wind direction is West wind, and when V is positive EWh When the value is negative, the wind direction is east wind.
(2) The principle of obtaining the fixed-point transmission flux through WRF-CAMx three-dimensional numerical model simulation is that the model belongs to an Euler three-dimensional grid model, a target area can be regarded as a three-dimensional box body (figure 1) formed by a plurality of grids, and each grid has a fixed three-dimensional space coordinate and can respectively provide meteorological elements and atmospheric pollutant concentrations of each grid in a research area. To obtain information about wind direction, wind speed and concentration of atmospheric pollutants at the same height above ground for each grid, facilitating comparison and verification with transmission flux stereographic data, WRF and CAMx are set to the same vertical number of layers (28 layers) and delta parameters, with the delta coordinates for each layer being 1.000,0.994,0.988,0.981,0.969,0.956,0.944,0.926,0.902,0.881, 0.852,0.828,0.796,0.754,0.704,0.648,0.589,0.546,0.495,0.445,0.387,0.287,0.187,0.136, 0.091,0.061,0.020,0.000, respectively. Table 1 gives the heights corresponding to the respective δ coordinates in the vertical direction.
TABLE 1 respective delta coordinates and corresponding heights in the vertical direction
The calculation formula is the product of the pollutant simulated concentration and the simulated wind speed, namely:
FLUX' NSh ＝C' ph ×v h
FLUX' EWh ＝C' ph ×u h
in the formula:
FLUX’ NSh -the fixed point transmission flux analog value of h meters atmospheric pollutants from the ground in the north-south direction with the unit of mu g.m -2 ·s -1 (ii) a When FLUX' NSh When positive, it is defined as the atmospheric pollutants entering from south to north when FLUX' NSh When the value is negative, the atmospheric pollutants are output from north to south;
FLUX’ EWh -the fixed point transmission flux analog value of the atmospheric pollutants with the height h meters above the ground in the east-west direction, and the unit is mu g.m -2 ·s -1 (ii) a When FLUX' EWh When positive, it is defined as atmospheric pollutants entering from west to east, when FLUX' EWh When the value is negative, the atmospheric pollutants are defined to be output from east to west;
C’ Ph atmospheric pollutants (e.g. O) at a height h meters above the ground 3 、PM 2.5 Etc.) in μ g/m 3 ；
V h -the wind vector simulation value in the south-north direction at the height h meter from the ground is m/s when V h When the value is positive, the wind direction is south wind, when V h When the value is negative, the wind direction is north wind.
u h -wind vector analog value in the east-west direction at a height h m from the ground in m/s when u h When the value is positive, the wind direction is West wind, and when u is positive h When the value is negative, the wind direction is east wind.
(3) The following example 1 is a transmission flux result obtained based on laser radar fixed-point observation from 12 days to 15 days in 1 month in 2019, and is compared and verified with a WRF-CAMx model simulation result (FIG. 2). 12 days near ground PM 2.5 The concentration reaches the maximum value of the heavy pollution, and the analog value and the observed value of the fixed-point transmission flux change by oneTherefore, the correlation coefficients are all above 0.92, the NMB value is-87.3% -24.1%, and the NME value is 28.8% -87.3%. 13 days near ground PM 2.5 The concentration is reduced but still a higher contamination level is maintained. Compared with the analog value of the fixed-point transmission flux, the correlation coefficient of the fixed-point transmission flux and the analog value of the fixed-point transmission flux is between 0.88 and 0.97, the index values of the two relative deviations are reduced, and the NMB value range and the NME value range are respectively-19.3 to 5.0 percent and 17.6 to 32.2 percent. On 14 days, the simulated values and the observed values have relatively consistent evolution trends in the vertical direction, wherein NMB is-20.4% and 84.2%, and NME is 44.8% and 84.2%, respectively. Day 15, PM 2.5 The concentration is reduced to a lower level, the change trend of the fixed-point transmission flux analog value is consistent with that of the observed value, the correlation coefficients are higher than 0.96, and the NMB value range and the NME value range are respectively-41.7% -18.4% and 19.5% -41.7%. In summary, the WRF-CAMx simulation system can better reproduce PM in heavy pollution period 2.5 The evolution of the transmitted flux.
Case 2: a method for calculating the sailing transmission flux based on mutual verification of laser radar sailing observation and model simulation.
The air traffic transmission flux refers to the mass of atmospheric pollutants passing through a specific vertical section per unit area per unit time.
The principle of acquiring the pollutant transmission flux by laser radar navigation observation is that based on the three-dimensional distribution result of the mass concentration of the atmospheric pollutants acquired by the laser radar through closed-loop navigation observation, the vertical distribution of the atmospheric pollutant transmission flux at different ground heights on a closed-loop monitoring path can be obtained by combining three-dimensional wind field information and the included angle between the vehicle driving azimuth and the wind direction. The calculation formula is as follows:
Flux(z)＝C P (z)×V(z)×sinθ
in the formula:
flux (z) -atmospheric contaminants (e.g. O) at height z from the ground 3 、PM 2.5 Etc.) in units of: μ g.m -2 ·s -1 ；
C P (z) -atmospheric contaminants (e.g. O) at a height z from the ground 3 、PM 2.5 Etc.) in units of: μ g.m -2 ·s -1 ；
V (z) -observed wind speed at height z from the ground in units: m/s;
sin theta is the included angle between the driving azimuth angle of the vehicle and the wind direction recorded by the GPS.
(2) Here, since the laser radar navigation observation flux is a closed-loop stereo observation value, for the verification of the navigation flux, a specific point concerned in the navigation observation is adopted to compare and verify with a grid point flux analog value simulated by a WRF-CAMx model, that is, the calculation method of the transmission flux analog value is consistent with that in case 1, and the method is not repeated here.
(3) The following example 2 is a transmission flux result obtained on a Beijing six-ring loop line of 10 months and 14 days in 2016 based on lidar sailing observation, and is compared and verified with a WRF-CAMx model simulation result (FIGS. 3-4). Compared with the observed value, the intensity of the simulated flux of the Hexagon ring is larger, but the intensity of the simulated flux of the Hexagon ring and the observed value are better consistent, and the correlation coefficient is 0.91. The intensity average value of the simulated flux at each height in the whole vertical direction ranges from-10.0 to-319.0 mu g.m -2 ·s -1 The mean value of the bulk strength was-118.3. mu.g.m -2 ·s -1 (ii) a The highest value of the simulated flux intensity is also 359m away from the ground and is-319.0 mu g.m -2 ·s -1 (ii) a And the intensity mean values below and above 611m from the ground are respectively-162.1 mu g m -2 ·s -1 And-59.8. mu.g.m -2 ·s -1 . Based on the comparison between the observed flux and the simulated flux of the east-six ring, the correlation coefficient of the evolution trend of the observed flux and the simulated flux in the vertical direction is 0.82, the observed value of the strength ratio of the simulated flux is higher, and the average strength range is-6.0 to-77.2 mu g.m -2 ·s -1 Mean value of-39.0. mu.g.m -2 ·s -1 The highest intensity occurred at a height of 359m from the ground, while the average flux was-51.0 μ g · m in the height ranges below and above 459m from the ground, respectively -2 ·s -1 And-26.9. mu.g.m -2 ·s -1 Higher than the observed flux.
Case 3: a cross-boundary transmission flux calculation method based on mutual verification of high altitude weather-near ground pollutant observation and model simulation.
Transmit flux across a boundary refers to the mass of atmospheric contaminants passing through a vertical cross-section at a particular time.
(1) Based on a certain point wind profiler and a near-ground conventional atmospheric pollutant monitoring device, the vertical distribution of wind vectors of the point and the mass concentration of near-ground conventional atmospheric pollutants can be obtained, and the concentration distribution of the pollutants in the vertical direction is lacked. For such a situation, if the cross-boundary transmission flux between the atmospheric pollutant in the target area and the surrounding adjacent area is calculated, the cross-boundary transmission flux can be analyzed by a point-by-point method, that is, the concentration of the near-surface atmospheric pollutant obtained by monitoring the point location is assumed to represent the concentration of the atmospheric pollutant in the whole target area, and the pollution concentration is uniformly distributed in the vertical direction; the concentration of the atmospheric pollutants near the ground in the adjacent areas can be obtained by downloading through an air quality website, and is also used as the overall concentration of each adjacent area, and the concentration distribution in the vertical direction is uniform. In addition, the wind vector at the junction of the target area and the adjacent area can be assumed based on the wind vector vertical data acquired by the wind profiler, and the wind vector is uniformly distributed, namely the wind vector values of the target area and the adjacent area all adopt the wind vector value of the point, so that the cross-boundary transmission flux between the target area and each adjacent area is calculated. The cross-boundary transmission flux calculation formula is as follows:
Flux u ＝∑ h L·H k ·c up ·u·8.64×10 -8
Flux v ＝∑ h L·H k ·c up ·v·8.64×10 -8
in the formula: flux u Trans-boundary transport flux of contaminants in the east-west direction, in units: t/d;
Flux v -trans-boundary transport flux of contaminants in north-south direction, unit: t/d;
h-vertical highest layer observed by wind profiler, unit: m;
l-the length of the boundary line where two adjacent regions contact, unit: m;
H k -height resolution in the vertical direction of the wind profiler, unit: m;
C up -mass concentration of atmospheric pollutants in upwind cities in units: mu.g/m 3 ；
u-wind speed in the east-west direction, unit: m/s;
v-wind speed in the north-south direction, in units: m/s.
(2) A method for simulating the transmission flux of atmospheric pollutants across boundaries based on a WRF-CAMx three-dimensional numerical model includes the steps of firstly selecting a target area, dividing the boundary of the atmospheric pollutants across the boundaries according to the method of administrative boundary lines of China, determining each adjacent area bordering the target area, and setting and calculating area boundary lines (figure 5). The purple curve represents administrative boundary lines of the region A and the region B, the simulation range is divided into different grids through grid region division in the model, and the red line represents the boundary lines of the region A and the region B in the model and is used for simulating and calculating the cross-boundary transmission flux of the atmospheric pollutant pollution.
Regarding the target areas as three-dimensional boxes formed by a plurality of grids, fig. 6 is a unit area infinitesimal vector of a certain vertical cross section in the box, wherein V represents the fluid flow velocity passing through the area infinitesimal, n represents the normal vector of the area infinitesimal, and c represents the mass concentration of the atmospheric pollutants at the area infinitesimal. And (3) calculating the quantity product of the flow velocity, the atmospheric pollutant concentration and the area of each infinitesimal on the cross section, and then integrating the whole cross section to obtain the mass of the atmospheric pollutants passing through the whole cross section in unit time.
The WRF-CAMx mode belongs to an Euler three-dimensional grid mode, each grid has a fixed three-dimensional space coordinate, and meteorological elements and atmospheric pollutant concentrations of each grid in a research area can be provided respectively. In addition, the WRF and CAMx are set to the same number of vertical layers (28 layers) and delta parameters in order to obtain the corresponding wind direction, wind speed and atmospheric pollutant concentration information at the same height above the ground for each grid. In summary, in the present study, it is required to calculate the discretization of the cross section according to the mesh division manner in the WRF and CAMx modes, and calculate the cross-boundary transmission flux of the atmospheric pollutants on the specific cross section by using the output data of the two modes, where the specific calculation formula is as follows:
in the formula: flux — the trans-boundary transport Flux of atmospheric pollutants, unit: t/d;
h-vertical highest layer of model setup, unit: m;
l-boundary line of two adjacent areas, unit: m;
l-simulation grid resolution, unit: km;
H k -simulating the height difference between the vertical layers k and k + 1;
c-atmospheric pollutants (e.g. O) 3 、PM 2.5 ) Mass concentration of (d), unit: mu.g/m 3 ；
v-wind direction and speed, unit: DEG and m/s;
n-normal vector through the vertical section, dimensionless.
Based on the above formula for calculating the cross-boundary transmission flux, the inflow flux and the outflow flux of the atmospheric pollutants at different heights from a single box body, a plurality of box bodies at the same height from the ground at the boundary line to all the box bodies in the vertical direction are respectively calculated by taking the inflow target area of the atmospheric pollutants as positive and the outflow target area as negative. The net flux refers to the vector sum of the inflow and outflow fluxes of atmospheric pollutants, where positive values represent the net inflow flux and negative values represent the net outflow flux.
FIG. 7 is PM at a vertical section of a single case 2.5 Inflow and outflow fluxes are illustrated.
Fig. 8 is a vertical cross-sectional illustration at the border line of the adjacent regions after discretization.
(3) The following example 3 is to take the cisternal region of beijing city as the target region, divide the prefecture/city bordering the same into 7 parts according to administrative boundaries, sequentially divide the prefecture/city into the Huairou region, the dense cloud region, the valley region, the Chang-Ping region, the Tongzhou region, the sunny region and the north region of the corridor city (fig. 9), perform wind field routine observation on the capital airport of beijing city based on a wind profiler, and obtain the wind field (wind speed and wind direction) along with the wind direction in the vertical direction of the capital airport siteThe method is characterized in that the method comprises the following steps of (1) representing the change conditions of different altitudes, and representing the wind profile data observed by the capital airport to the change conditions of the wind field in the cis-region. Meanwhile, the research obtains PM of 7 neighboring areas/cities on the periphery of the sense based on the pollutant concentration statistical data of the environment monitoring stations in Beijing City and corridor City 2.5 Hourly concentration value and assuming PM within 1300m height from the ground 2.5 The concentration is the same as the near-surface concentration, and PM is calculated 2.5 Observed values of cross-regional/urban traffic. In addition, based on the WRF-CAMx mode, the wind field and PM at the boundary line of less than 10 layers (about 1300m away from the ground) of the cis-zone and 7 zones/cities around the cis-zone and the PM in the vertical direction in the model are extracted 2.5 Concentration information, calculating PM 2.5 Analog values of trans-regional/urban transmission flux. Finally, the PM is mixed 2.5 And comparing and analyzing the observed value and the simulated value of the transmission flux, and verifying the accuracy of the WRF-CAMx model simulation.
FIG. 10 shows different seasons representing months (1 month, 4 months, 7 months, 10 months) of the same definition and the surrounding areas PM 2.5 The net flux analog is vertically distributed from the observed values. Wherein the inflow flux is positive and represents the input PM of the peripheral zone/city-to-cis zone 2.5 The outflow flux is negative and represents the output PM to the peripheral area/market area 2.5 (ii) a The net flux is the vector sum of the inflow and outflow fluxes, with positive values representing net inflow, indicating a peri/city-to-cis input PM 2.5 Higher than the output from the cis zone, negative values represent net outflow, indicating that the cis zone outputs PM to the peripheral/urban zone 2.5 Is higher than the input from the periphery. The results show that: PM (particulate matter) 2.5 The correlation coefficient ranges of the analog values and the observed values of the inflow flux, the outflow flux and the net flux are 0.48-0.92, 0.71-0.96 and 0.49-0.98 respectively, the NMB value ranges from 6.0% to 69.1%, -71.7% to 54.5% and-50.0% to 76.2%, and the NME ranges from 10.6% to 85.5%, 18.7% to 71.7% and 21.3% to 79.2%. The reason for the relatively high NMB and NME errors is that the study assumes a PM within 1300m 2.5 The concentration of each grid observation point in the vertical direction is the same as that of PM 2.5 The actual distribution of concentrations will vary, but in general, PM will be 2.5 The flux analog value is consistent with the observed value, which shows that the WRF-CAMx mode simulation can be used for researching the sense and the peripheryDistrict PM 2.5 The flux is transmitted across the boundary. Especially PM below 400m in 1 month, 4 months, 7 months and 10 months 2.5 The total net flux analog values are-28.99 t/d, 27.04t/d, 13.50t/d and-37.76 t/d respectively, and the observed values are-24.32 t/d, 16.41t/d, 7.89t/d and-29.20 t/d respectively; PM above 400m 2.5 The total net flux analog values are-125.13 t/d, 87.71t/d, 14.71t/d and-236.22 t/d respectively, the observed values are-87.46 t/d, 64.49t/d, 23.20t/d and-166.09 t/d respectively, and the analog values of the net flux and the observed values basically change in the vertical direction. In general, the simulated value of the total net flux is generally higher than the observed value (except for 7 months), which may be related to the simulated value of the wind speed being higher; the relative error ranges below 400m and above 400m are respectively 19.2% -71.1% and-36.6% -43.1%, and within an acceptable range, the WRF-CAMx mode can be used for further carrying out simulation research on transmission flux across cities, provinces and regions.
The invention also provides a method for identifying the polluted transmission channel based on the pollutant cross-boundary transmission flux, which comprises the following steps:
based on a WRF-CAMx three-dimensional numerical model, the inflow flux, the outflow flux and the net flux of the atmospheric pollutants between each city and the adjacent periphery in the research area can be obtained through simulation, and according to the inflow and outflow directions of the atmospheric pollutants of each target city, all the inflow and outflow directions of the cities in the target area are combed and integrated, so that the integral inflow and outflow directions of the atmospheric pollutants in the area are obtained, and further, the transmission channel in the target area is identified.
For example, based on WRF-CAMx three-dimensional numerical model simulation, the Jingjin Ji area is used as an example for PM of typical cities (Beijing, Tianjin, Shijiazhuang and Tangshan) in the Jingjin Ji area, the Jingjin Ji whole area and the surrounding provinces 2.5 The cross-border transmission flux was simulated to identify the direction of transmission between cities and between the kyojin ji area and the surrounding provinces, where "↘, ↗, →, and ↖" represent northwest to southeast, southwest to northeast, west to east, and southeast to northwest, respectively (table 2). Identifying PM of 1 month, 4 months, 7 months and 10 months in Jingjin Ji area 2.5 Contaminating the main transport channels (fig. 11).
Table 22016 transmission paths and main directions of cities and areas of 1 month, 4 months, 7 months and 10 months
In the above, based on meteorological observation, laser radar stereo observation and three-dimensional numerical simulation technology, the method is used for establishing a calculation method of fixed-point transmission flux, navigation transmission flux and cross-boundary transmission flux for various pollutants and different situations, and realizing comparison and verification of flux quantification results obtained by stereo observation and model simulation; the method for identifying the main transmission channel of the atmospheric pollutants is established based on the cross-regional transmission flux quantification result of the atmospheric pollutants across counties, cities and regions.
Claims (5)
1. A multi-pollutant cross-boundary transmission flux quantification integration technical method is characterized in that a fixed point transmission flux observed value and a simulation value of a pollutant are respectively obtained based on laser radar fixed point observation and a WRF-CAMx three-dimensional numerical model, and then model parameters are adjusted by analyzing the accuracy of simulation result verification so as to optimize the WRF-CAMx three-dimensional numerical model and improve the model simulation accuracy; wherein:
when the laser radar performs fixed-point observation to obtain a fixed-point transmission flux observed value of a pollutant, the laser radar performs online observation based on the laser radar and a wind profiler, and combines a three-dimensional distribution structure of the mass concentration of the atmospheric pollutant obtained by two devices with three-dimensional wind field data to obtain the vertical distribution of the transmission flux of the atmospheric pollutant at different heights of an observation station; the fixed-point transmission flux observed value is the product of the monitored mass concentration and the wind vector of the atmospheric pollutants, and the calculation formula is as follows:
FLUX NSh ＝C ph ×V NSh
FLUX EWh ＝C ph ×V EWh
in the formula:
FLUX NSh -the observed value of the fixed point transmission flux of the atmospheric pollutants with the height h meters above the ground in the south and north directions and the unit of the observed value is mu g.m -2 ·s -1 (ii) a When FLUX NSh When the value is positive, it is defined as the input of atmospheric pollutants from south to north, when FLUX NSh When the value is negative, the atmospheric pollutants are output from north to south;
FLUX EWh -the observed value of the fixed-point transmission flux of the atmospheric pollutants with the height h meters above the ground in the east-west direction is in units of mu g.m -2 ·s -1 (ii) a When FLUX EWh When the value is positive, it is defined that the atmospheric pollutant is input from west to east, when FLUX EWh When the value is negative, the atmospheric pollutants are defined to be output from east to west;
C Ph atmospheric pollutants (e.g. O) at a height h meters above the ground 3 、PM 2.5 Etc.) in units of μ g/m 3 ；
V NSh -the observed value of the wind vector in the south-north direction at the height h m from the ground is m/s when V NSh When the value is positive, the wind direction is south wind, when V NSh When the value is negative, the wind direction is north wind;
V EWh -the observed value of the wind vector in the east-west direction at the height h m from the ground in m/s when V EWh When the value is positive, the wind direction is West wind, and when V is positive EWh When the value is negative, the wind direction is east wind;
when a WRF-CAMx three-dimensional numerical model is used for simulating and obtaining a fixed-point transmission flux simulation value, a target area is regarded as a three-dimensional box body formed by a plurality of grids, each grid has a fixed three-dimensional space coordinate, and meteorological elements and atmospheric pollutant concentrations of each grid in a research area are respectively provided; in order to obtain wind direction, wind speed and concentration information of atmospheric pollutants corresponding to the same height above the ground of each grid, and to facilitate comparison and verification with transmission flux stereo observation data, WRF and CAMx are set to be the same vertical layer number and delta coordinate parameters, wherein the delta coordinate parameter is a coordinate parameter defined for setting the height of each vertical layer in the vertical direction in a WRF meteorological model, the value range of the delta coordinate parameter is [0-1], and the WRF meteorological model automatically sets the height of each vertical layer according to the set delta coordinate parameter; the fixed point transmission flux analog value is the product of pollutant analog mass concentration and analog wind vector, wherein the pollutant analog mass concentration is obtained through CAMx air quality model simulation, the analog wind vector comprises wind direction and wind speed, and is obtained through WRF meteorological model simulation, and the calculation formula is as follows:
FLUX' NSh ＝C' ph ×v h
FLUX' EWh ＝C' ph ×u h
in the formula:
FLUX’ NSh -the fixed point transmission flux analog value of h meters atmospheric pollutants from the ground in the north-south direction with the unit of mu g.m -2 ·s -1 (ii) a When FLUX' NSh When positive, it is defined as the air pollutant entering from south to north when FLUX' NSh When the value is negative, the atmospheric pollutants are output from north to south;
FLUX’ EWh -the fixed point transmission flux analog value of the atmospheric pollutants with the height h meters above the ground in the east-west direction, and the unit is mu g.m -2 ·s -1 (ii) a When FLUX' EWh When positive, it is defined as atmospheric pollutants entering from west to east, when FLUX' EWh When the value is negative, the atmospheric pollutants are defined to be output from east to west;
C’ Ph atmospheric pollutants (e.g. O) at a height h meters above the ground 3 、PM 2.5 Etc.) in μ g/m 3 ；
V h -the wind vector simulation value in the south-north direction at the height h meter from the ground is m/s when V h When the value is positive, the wind direction is south wind, and when V is positive h When the value is negative, the wind direction is north wind.
u h -wind vector analog value in the east-west direction at a height h m from the ground in m/s when u h When the value is positive, the wind direction is West wind, and when u is positive h When the value is negative, the wind direction is east wind.
2. The multi-pollutant cross-boundary transmission flux quantitative integration technical method is characterized in that an observed value and a simulated value of the cross-boundary transmission flux of a pollutant are respectively obtained based on laser radar navigation observation and WRF-CAMx three-dimensional numerical model simulation, and then model parameters are adjusted by analyzing the accuracy of simulation result verification so as to optimize the WRF-CAMx three-dimensional numerical model and improve the model simulation accuracy; wherein:
when the laser radar sailing observation obtains a sailing transmission flux observation value of pollutants, the vertical distribution of the transmission flux of the atmospheric pollutants at different ground heights on a closed-loop monitoring path is obtained by combining three-dimensional wind field information and an included angle between a vehicle driving azimuth and a wind direction based on a three-dimensional distribution result of the mass concentration of the atmospheric pollutants obtained by the laser radar through closed-loop sailing observation; the calculation formula of the observation value of the navigation transmission flux is as follows:
Flux(z)＝C P (z)×V(z)×sinθ
in the formula:
flux (z) -airborne transport flux of atmospheric pollutants at height z from the ground in units: μ g.m -2 ·s -1 ；
C P (z) -mass concentration of atmospheric pollutants at height z from the ground in units: μ g.m -2 ·s -1 ；
V (z) -observed wind speed at height z from the ground in units: m/s;
sin theta is the included angle between the vehicle running azimuth and the wind direction recorded by the GPS;
and when the sailing transmission flux analog value is calculated, comparing and verifying the specific point position concerned in sailing observation and the specific grid point position flux analog value simulated by the WRF-CAMx model, namely, the sailing transmission flux analog value is the product of the pollutant analog concentration and the analog wind vector.
3. The multi-pollutant cross-boundary transmission flux quantitative integration technical method is characterized in that an observed value and a simulated value of cross-boundary transmission flux of pollutants are respectively obtained based on high-altitude weather-near-ground pollutant observation and WRF-CAMx three-dimensional numerical model simulation, and then model parameters are adjusted by analyzing the accuracy of simulation result verification so as to optimize the WRF-CAMx three-dimensional numerical model and improve the model simulation accuracy;
when calculating the cross-boundary transmission flux observed value of the atmospheric pollutants in the target area and the adjacent areas, considering the atmospheric pollutant monitoring concentration and wind vector observed value of the target area and the adjacent areas; for the atmospheric pollutant monitoring concentration, the concentration of the near-surface atmospheric pollutants obtained by monitoring the point position of the target area through a near-surface conventional atmospheric pollutant monitoring device is assumed to represent the concentration of the atmospheric pollutants in the whole target area, the pollution concentration is uniformly distributed in the vertical direction, the concentration of the near-surface atmospheric pollutants in the adjacent areas is obtained by downloading through an air quality website and is also used as the whole concentration of each adjacent area, and the concentration is uniformly distributed in the vertical direction; for the observed value of the wind vector, the wind vector at the border between the target area and each adjacent area is assumed to be consistent, that is, the wind speed and the wind direction of the target area and each adjacent area are obtained by adopting a wind profiler erected based on the target area; on the basis, calculating a cross-boundary transmission flux observed value between the target region and each adjacent region; the formula for calculating the cross-boundary transmission flux observed value is as follows:
Flux u ＝∑ h L·H k ·c up ·u·8.64×10 -8
Flux v ＝∑ h L·H k ·c up ·v·8.64×10 -8
in the formula: flux u Trans-boundary transport flux of contaminants in the east-west direction, in units: t/d;
Flux v -trans-boundary transport flux of contaminants in north-south direction, unit: t/d;
h-the vertical highest layer observed by the wind profiler, unit: m;
l-the length of the boundary line where two adjacent regions contact, unit: m;
H k -height resolution in the vertical direction of the wind profiler, units：m；
C up -mass concentration of atmospheric pollutants in upwind cities in units: mu g/m 3 ；
u-wind speed in the east-west direction, unit: m/s;
v-wind speed in the north-south direction, in units: m/s.
A method for simulating the cross-boundary transmission flux of atmospheric pollutants based on a WRF-CAMx three-dimensional numerical model is as follows: firstly, selecting a target area, dividing the boundary of the cross-boundary transmission of the atmospheric pollutants according to an administrative boundary line method, determining each adjacent area bordering the target area, and dividing a simulation range into different grids for simulating and calculating the cross-boundary transmission flux of the atmospheric pollutants through gridding division in a model;
the target area is regarded as a three-dimensional box body formed by a plurality of grids, a certain vertical section in the box body is selected, the product of the flow velocity of each infinitesimal element on the section, the concentration of the atmospheric pollutants and the area is calculated, and then the integral is carried out on the whole section, so that the mass of the atmospheric pollutants passing through the whole section in unit time is obtained;
the WRF-CAMx mode belongs to an Euler three-dimensional grid mode, each grid has a fixed three-dimensional space coordinate, a section needing to be calculated is discretized according to a grid division mode in the WRF and CAMx modes, the cross-boundary transmission flux of the atmospheric pollutants on the specific section is calculated by using output data of the two modes, and a specific calculation formula is as follows:
in the formula: flux — the trans-boundary transport Flux of atmospheric pollutants, unit: t/d;
h-vertical highest layer of model setup, unit: m;
l-boundary line of two adjacent areas, unit: m;
l-simulation grid resolution, unit: km;
H k between the simulated vertical layers k and k +1The height difference of (a);
c-mass concentration of atmospheric pollutants, unit: mu g/m 3 ；
v-wind direction and speed, unit: DEG and m/s;
n-normal vector through vertical section, dimensionless;
based on a cross-boundary transmission flux calculation formula, respectively calculating inflow fluxes and outflow fluxes of atmospheric pollutants at different ground heights from a single box body, a plurality of box bodies at the same ground height on a boundary line to all box bodies in the vertical direction by taking the inflow target area of the atmospheric pollutants as positive and the outflow target area as negative; the net flux refers to the vector sum of the inflow and outflow fluxes of atmospheric pollutants, where positive values represent the net inflow flux and negative values represent the net outflow flux.
4. The multi-pollutant cross-boundary transmission flux quantitative integration technical method as claimed in one of claims 1 to 3, characterized in that observed values and simulated values of the transmission flux of pollutants are compared and verified by introducing correlation coefficients COR, normalized mean deviation NMB and normalized mean error NME statistical indexes, and the accuracy of verification of the simulated results is analyzed.
5. A method for identifying a contaminated transport channel based on the multi-contaminant cross transport flux quantification and integration technique of claim 3, comprising the steps of:
based on an optimized WRF-CAMx three-dimensional numerical model, inflow flux, outflow flux and net flux in the cross-boundary transmission flux of the atmospheric pollutants between each city and the adjacent periphery in the research area are obtained through simulation, all city inflow and outflow directions in the target area are combed and integrated according to the inflow and outflow directions of each target city atmospheric pollutant, and therefore the overall inflow and outflow directions of the atmospheric pollutants in the area are obtained, and further the transmission channel in the target area is identified.
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| US20160091474A1 (en) * | 2014-09-29 | 2016-03-31 | Tanguy Griffon | Method and a System for Determining at Least One Forecasted Air Quality Health Effect Caused in a Determined Geographical Area by at Least One Air Pollutant |
| CN110031412A (en) * | 2019-04-25 | 2019-07-19 | 中国科学技术大学 | Air Pollutant Emission flux acquisition methods based on mobile AHSA observation |
| CN110569528A (en) * | 2019-07-15 | 2019-12-13 | 北京工业大学 | Numerical simulation quantification method for PM2.5 transmission flux below atmospheric boundary layer of cross-boundary region |
| CN113804829A (en) * | 2021-08-20 | 2021-12-17 | 重庆市生态环境监测中心 | Atmospheric pollution space-air-ground integrated real-time monitoring system and method |
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