A method and system for tracing the source of stratospheric intrusion affecting tropospheric ozone pollution

Abstract

The present invention discloses a method and system for tracing the stratospheric intrusion affecting tropospheric ozone pollution. The method includes: calculating the pulsation of stratospheric ozone tracers in the troposphere of the target area based on EAC4 data; calculating the tropopause folding frequency in different regions and different periods according to the potential vorticity, geopotential temperature and specific humidity based on ERA5 data; then calculating the correlation and confidence interval between the time series of ozone in the target area and the tropopause folding frequency in each region according to the pulsation of stratospheric ozone tracers in the troposphere of the target area and the tropopause folding frequency in different regions, and determining the long-term high-frequency stratospheric source area affecting the tropospheric ozone in the target area; finally, determining the transmission path of stratospheric ozone intrusion according to the correlation and confidence interval between the pulsation of stratospheric ozone tracers in the target area offset by a preset number of days and the tropopause folding frequency in each region. The present invention can more accurately identify the long-term high-frequency stratospheric source area that can affect tropospheric ozone pollution.

Description

Technical Field

[0001] A method and system for tracing the source of stratospheric intrusion affecting tropospheric ozone pollution Background Art

[0002] SIs (Stratospheric Intrusions) refer to the phenomenon that stratospheric air, usually at altitudes above 12 - 15 km above the ground, enters the troposphere through atmospheric dynamic processes such as tropopause folding and jet stream sinking, affecting the composition of the tropospheric atmosphere. For example, when a stratospheric intrusion occurs, the ozone-rich stratospheric air will enter the troposphere and even reach the ground, causing an increase in tropospheric ozone concentration and even ozone pollution events. Therefore, stratospheric intrusion has important impacts on air quality, climate change, and human health.

[0003] Currently, the source tracing method of stratospheric intrusion mainly relies on particle tracking methods. For example, first, typical cases where stratospheric intrusion affects tropospheric air are screened out through ground air quality observation data, and then a large number of particles are placed in the troposphere and the Lagrangian backward tracking method is used to trace the source area of the particle swarm, so as to identify the key source area of the stratospheric intrusion affecting the ground case. However, due to the high computational complexity and computational efficiency constraints of the Lagrangian source tracing model, this method can only trace the source of individual cases of stratospheric intrusion and cannot obtain the long-term high-frequency source areas of stratospheric intrusion affecting the tropospheric ozone in the area of concern. Moreover, since the chemical reactions of stratospheric ozone during the intrusion process are not considered in the Lagrangian model, the calculation accuracy is also limited. Summary of the Invention

[0004] In view of the problems existing in the prior art, the present invention provides a method for tracing the source of stratospheric intrusion affecting tropospheric ozone pollution, which can determine the long-term high-frequency source areas of stratospheric intrusion affecting the tropospheric ozone in different regions and can reduce the complexity of source tracing.

[0005] To solve the above technical problems, the present invention provides the following technical solution: A method for tracing the source of stratospheric intrusion affecting tropospheric ozone pollution, comprising the following steps:

[0006] S1. Based on the latest reanalysis dataset of global atmospheric composition, calculate the pulsation quantity of stratospheric ozone tracer in the troposphere within the preset longitude and latitude range of the target area; extract the stratospheric ozone tracer data at the 850 hPa height layer of the troposphere within the longitude and latitude range of the target area from the latest reanalysis dataset of global atmospheric composition, and then perform detrending to process it into the pulsation quantity of stratospheric ozone tracer.

[0007] S2. Based on the fifth-generation atmospheric reanalysis dataset of global climate, calculate the long-term time series of the daily average value of the tropopause folding frequency in different regions and different periods according to the potential vorticity, potential temperature, and specific humidity.

[0008] Specifically, for the fifth-generation atmospheric reanalysis dataset of the global climate, a 3D tagging algorithm program is used to call the potential vorticity, potential temperature, and specific humidity, and the following criteria are used to identify stratospheric air: potential vorticity: |PV| > 2 pvu, potential temperature: theta > 380K, specific humidity q < 0.1 g / kg, and the connectivity of grid points with |PV| > 2 pvu to the stratosphere or the ground.

[0009] For the fifth-generation atmospheric reanalysis dataset of the global climate, a 3D tagging algorithm program is used to calculate the tropopause fold frequency in different regions at different times, including the following sub-steps:

[0010] S2.1: Based on the criteria for identifying stratospheric air, a label from 1 to 5 is assigned to the atmosphere at each grid point. Label 1: tropospheric air; Label 2: stratospheric air; Label 3: PV anomaly air generated by stratospheric truncation; Label 4: PV anomaly air generated by tropospheric truncation; Label 5: PV anomaly air generated by topographic changes;

[0011] S2.2: For each region, in the vertical direction, from high altitude vertically downwards, if the change in air labels shows a transition of 2->1->2->1 or 2->1->2->3, it is identified as a tropopause fold phenomenon, and the hourly fold label for this region f = 1. If no tropopause fold phenomenon is identified, the fold label f = 0;

[0012] S2.3: Calculate the daily tropopause fold frequency for each region as follows:

[0013] ,

[0014] S3: According to the long-term time series of the stratospheric ozone tracer pulsation in the troposphere of the target region and the daily average value of the tropopause fold frequency in different regions, calculate the correlation and confidence interval between the stratospheric ozone tracer pulsation in the target region and the time change series of the tropopause fold frequency in each region, and determine the long-term high-frequency source region of the stratosphere that affects the tropospheric ozone in the target region;

[0015] S4: According to the correlation and confidence interval between the stratospheric ozone tracer pulsation offset by the preset number of days in the target region and the tropopause fold frequency in each region, determine the transmission path of stratospheric ozone intrusion.

[0016] Furthermore, in the aforementioned step S3, when calculating the correlation between the stratospheric ozone tracer pulsation in the target region and the time change series of the tropopause fold frequency in each region, specifically, the Pearson correlation coefficient r is calculated as follows:

[0017] ,

[0018] In the formula, is the i-th value of variable X, where X is the pulsation of stratospheric ozone tracer in the target area, is the average value of variable X, is the i-th value of variable Y, where Y is the time series of the tropopause folding frequency in each area, is the average value of variable Y.

[0019] Furthermore, for calculating the confidence intervals of ozone in the target area and the time series of the tropopause folding frequency in each area as described above, specifically, the P-value is calculated as follows:

[0020]

[0021] In the formula, t is the test statistic, , n represents the total number of time series data points used for correlation analysis, T df is the cumulative distribution function of the t-distribution.

[0022] Furthermore, in the aforementioned step S3, the grid points with a correlation coefficient greater than 0.2 and a P-value less than 0.1 are screened and determined as the long-term high-frequency source areas of the stratosphere affecting the tropospheric ozone in this area, and their latitudes and longitudes are output at the same time.

[0023] Furthermore, in the aforementioned step S4, the correlation coefficient and P-value between the tropopause folding frequency and the ozone pulsation offset by 1 - 3 days are calculated to determine the spatial position change of the stratospheric source area and determine the transmission path of stratospheric ozone invasion

[0024] On the other hand, the present invention provides an electronic device, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the computer program, the steps of the method described in any one of the present invention are implemented.

[0025] The present invention also provides a computer-readable storage medium, on which a computer program is stored. It is characterized in that when the computer program is executed by a processor, the steps of the method described in any one of the present invention are implemented.

[0026] Compared with the prior art, the beneficial technical effects of the present invention adopting the above technical solutions are as follows:

[0027] 1. This method can not only be used for tracing individual cases of single stratospheric intrusion events, but also determine the long-term high-frequency source areas of the stratosphere affecting the area of concern, and the conclusion has universality.

[0028] 2. If this method is applied to other regions, only the longitude and latitude range for extracting O3S data from EAC4 needs to be modified, and then by using the same method, the stratospheric source regions affecting other regions can be traced. Therefore, this method is very easy to apply to various regions.

[0029] 3. This method directly conducts source tracing based on existing databases and statistical methods without the need to apply approximate methods such as models or parameterizations. Therefore, the results are more reliable.

[0030] In the future, if there are more accurate datasets compared to the EAC4 and ERA5 datasets, they can be replaced to make the source tracing more accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a schematic flow diagram of the present invention.

[0032] Figure 2 is a schematic diagram of air with different labels in the embodiment.

[0033] Figure 3 is a schematic diagram of O3S data.

[0034] Figure 4 is a schematic diagram of the running of the ERA5 dataset download script of the present invention.

[0035] Figure 5 is a spatial distribution map of the stratospheric high-frequency source regions affecting tropospheric ozone in a certain city in December.

[0036] Figure 6 is a comparison chart of the folding frequency of the high-frequency source region and the O3S pulsation quantity in a certain city in December.

[0037] Figure 7 is a spatial distribution map of the stratospheric high-frequency source regions affecting tropospheric ozone in a certain city in December with a one-day offset.

[0038] Figure 8 is a comparison chart of the folding frequency of the high-frequency source region and the O3S pulsation quantity with a one-day offset in a certain city in December. DETAILED DESCRIPTION OF THE INVENTION

[0039] To better understand the technical content of the present invention, specific embodiments are hereby given and described in conjunction with the accompanying drawings as follows.

[0040] Aspects of the present invention are described with reference to the accompanying drawings, in which a number of illustrative embodiments are shown. Embodiments of the present invention are not limited to those described in the drawings. It should be understood that the present invention can be implemented by any one of the various concepts and embodiments introduced above, as well as the concepts and embodiments described in detail below, because the concepts and embodiments disclosed in the present invention are not limited to any embodiment. Additionally, some aspects disclosed in the present invention can be used alone, or in any suitable combination with other aspects disclosed in the present invention.

[0041] Reference Figure 1 , the present invention provides a method for tracing the stratospheric intrusion affecting tropospheric ozone pollution. Taking the tracing of tropospheric ozone pollution in a certain city in December 2022 as an example, the steps are as follows:

[0042] S1. Based on the latest reanalysis dataset of global atmospheric composition, calculate the stratospheric ozone tracer pulse quantity in the troposphere within the preset longitude and latitude range of the target area.

[0043] To calculate the stratospheric ozone pulse quantity reaching the troposphere of a certain city, first download the latest reanalysis dataset of global atmospheric composition (EAC4 dataset). The download website is:

[0044] https: / / ads.atmosphere.copernicus.eu / datasets / cams-global-reanalysis-eac4?tab=download. EAC4 (the fourth generation of ECMWF atmospheric composition reanalysis) is the latest reanalysis dataset of global atmospheric composition by the European Centre for Medium-Range Weather Forecasts (ECMWF). This dataset combines model data with observational data from around the world and constructs an atmospheric model based on physical and chemical laws to form a complete and consistent global dataset. The horizontal resolution of the EAC4 dataset is 0.75°×0.75°, the vertical resolution is 60 model levels, the time coverage ranges from 2003 to 2022, and the time resolution is once every 3 hours.

[0045] Using a self-written python program, extract the stratospheric ozone tracer data (O3S) at the 850 hPa height level of the troposphere in a certain city (40.767°N, 114.917°E) from the EAC4 dataset. This data can represent the concentration distribution of ozone generated in the stratosphere in the troposphere. De-trend the extracted O3S data at 850 hPa, process it into a pulse quantity (daily average value minus monthly average), and save it as a csv format data. The effect after processing is as Figure 3 shown.

[0046] S2. Based on the fifth-generation atmospheric reanalysis dataset of the global climate, calculate the tropopause folding frequency in different regions and different periods according to the potential vorticity, potential temperature and specific humidity.

[0047] Use a self-written Python download script to set the start time and end time (year, month, day), set the target area and required variables (potential vorticity, specific humidity, potential temperature, etc.), and download the relevant fifth-generation atmospheric reanalysis dataset of the global climate (ERA5 dataset). The download website is:

[0048] https: / / cds.climate.copernicus.eu / datasets / reanalysis-era5-pressure-levels?tab=download. ERA5 is the fifth-generation atmospheric reanalysis dataset of the global climate released by the European Centre for Medium-Range Weather Forecasts (ECMWF). This data provides hourly, daily, and monthly global grid meteorological data since 1979, including various variables such as 2m air temperature, air pressure, wind speed, and relative humidity of the atmosphere, land, and ocean climates. The horizontal coverage of ERA5 is 90°N–90°S, and the resolution is 0.25°×0.25°. In the embodiment, the start time and end time are set as: December 1, 2022, and December 31, 2022. Set a certain city (40.767°N, 114.917°E) and the required variables (potential vorticity, specific humidity, and potential temperature), and use the script to download the relevant ERA5 data. The running interface of the download script is shown in Figure 4 .

[0049] Then, use a 3D tagging algorithm program on the ERA5 data to calculate the tropopause folding frequency in different regions and different periods to represent the stratospheric intrusion intensity in different regions and different periods. This program identifies stratospheric air by calling the potential vorticity, potential temperature, and specific humidity in the ERA5 data, and uses the following criteria: potential vorticity (|PV|>2 pvu), potential temperature (theta>380K), specific humidity q<0.1g / kg, and the connectivity of grid points with |PV|>2 pvu to the stratosphere or the ground. Based on these criteria, the algorithm program assigns a label from 1 to 5 to the atmosphere at each grid point, as shown in Figure 2 . The meanings of each label are: Label 1: Tropospheric air; Label 2: Stratospheric air; Label 3 (PV anomaly air generated by stratospheric truncation), Label 4 (PV anomaly air generated by tropospheric truncation), Label 5 (PV anomaly air generated by topographic changes).

[0050] The algorithm determines that: in the vertical direction, from high altitude vertically downwards, if the change of the air label shows a conversion of 2->1->2->1 or 2->1->2->3, it is recognized as a tropopause folding phenomenon, and the hourly folding label f of the area is 1. If the tropopause folding phenomenon is not recognized, the folding label f = 0. Calculate the tropopause folding frequency of a certain city daily as follows:

[0051] ,

[0052] where, f is the hourly tropopause folding label of a certain city.

[0053] S3. According to the stratospheric ozone tracer pulsation in the troposphere of the target area and the tropopause folding frequencies in different regions, calculate the correlation and confidence interval between the ozone in the target area and the time variation series of the tropopause folding frequencies in each region, and determine the long-term high-frequency source area of the stratosphere affecting the tropospheric ozone in the target area.

[0054] As a preferred embodiment of the present invention, in step S3, when calculating the correlation between the stratospheric ozone tracer pulsation in a certain city and the time variation series of the tropopause folding frequencies in each region, specifically calculate the Pearson correlation coefficient r as follows:

[0055] ,

[0056] In the formula, is the i-th value of variable X, X is the stratospheric ozone tracer pulsation in a certain city, is the average value of variable X, is the i-th value of variable Y, Y is the time variation series of the tropopause folding frequencies in each region, is the average value of variable Y.

[0057] When calculating the confidence interval between the ozone in a certain city and the time variation series of the tropopause folding frequencies in each region, specifically calculate the P value as follows:

[0058] ,

[0059] In the formula, t is the test statistic, , n represents the total number of time series data points used for correlation analysis, T df is the cumulative distribution function of the t-distribution.

[0060] Screen the grid points with a correlation coefficient greater than 0.2 and a P value less than 0.1, determine them as the long-term high-frequency source area of the stratosphere affecting the tropospheric ozone in this region, and output their longitude and latitude at the same time.

[0061] S4. Determine the transmission path of stratospheric ozone intrusion based on the correlation and confidence interval between the pulsation of stratospheric ozone tracers offset by a preset number of days in the target area and the tropopause folding frequency in each area. In this embodiment, the pulsation of stratospheric ozone tracers offset by 1 - 3 days in the target area is selected.

[0062] Figure 5 The schematic diagram of the high - frequency stratospheric source area affecting tropospheric ozone in a certain city in December is shown. The results show that the stratospheric source areas affecting the tropospheric ozone in this city in December 2022 are located at: 30°N, 110°E (south), 30°N, 90°E (southwest), and 55°N, 70°E (northwest), and its spatial distribution characteristics are consistent with the research results of typical stratospheric intrusion events in North China. Figure 6 It is a comparison chart of the folding frequency of the high - frequency source area and the O3S pulsation in this city in December. It can be seen that the correlation between the tropospheric O3S pulsation in this city in December and the tropopause folding frequency of this high - frequency source area is good. When the tropopause folding frequency increases on December 6th, 24th, and 29th in the source area, the O3S pulsation in this city synchronously shows a positive anomaly (ΔO3S>1.5). In addition, the changes in the tropopause folding frequency of the rest of this source area also coincide with the changes in the O3S pulsation value in this city, and it is determined as the high - frequency stratospheric source area affecting the tropospheric ozone in this city this month. Figure 7 The spatial distribution of the high - frequency stratospheric source area affecting this city in December 2022 offset by 1 day is shown. The tracing result shows that the stratospheric ozone in the source area located in the south of this city (28°N, 105°E) will affect the tropospheric ozone in this city after 24 - hour transportation. The difference between this source area and the pre - offset position is small, and there is a possibility of transmission. Figure 8 It shows that when the tropopause folding frequency in the source area significantly increases from December 26th to 29th, a positive anomaly in the O3S pulsation occurs in this city on the next day. It is confirmed that the stratospheric ozone in this source area affects the tropospheric ozone in this city after 24 hours, reflecting the spatial transmission path of stratospheric ozone intrusion into this city in December 2022.

[0063] On the other hand, the present invention provides an electronic device, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the computer program, the steps of any method described in the present invention are implemented.

[0064] The present invention also provides a computer - readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of any method described in the present invention are implemented.

[0065] Adopting the technical solution of the present invention can identify the long-term high-frequency source regions in the stratosphere that have a significant impact on tropospheric ozone pollution in different regions of our country (such as North China, East China, South China, etc.). It can also help relevant departments formulate more accurate and effective ozone pollution prevention and control measures. For example, targeted at the ozone pollution characteristics and stratospheric intrusion contributions in different regions and seasons, differential emission reduction and control strategies are adopted to improve air quality.

[0066] Although the present invention has been described above with preferred embodiments, it is not intended to limit the present invention. Those with ordinary knowledge in the technical field to which the present invention pertains can make various modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to that defined by the claims.

Claims

1. A method for tracing the source of stratospheric intrusion affecting tropospheric ozone pollution, characterized in that, It includes the following steps: S1. Calculate the stratospheric ozone tracer pulse quantity in the troposphere within the preset longitude and latitude range of the target area based on the latest reanalysis dataset of global atmospheric composition; Specifically: Extract the stratospheric ozone tracer data at the 850 hPa height layer of the troposphere within the longitude and latitude range of the target area from the latest reanalysis dataset of global atmospheric composition, and then perform detrending to process it into the stratospheric ozone tracer pulse quantity; S2. Based on the fifth-generation atmospheric reanalysis dataset of global climate, calculate the long-term time series of the daily average of the tropopause folding frequency in different regions and different periods according to the potential vorticity, potential temperature, and specific humidity; Specifically: Use the 3D tagging algorithm program for the fifth-generation atmospheric reanalysis dataset of global climate, call the potential vorticity, potential temperature, and specific humidity, and use the following criteria to distinguish stratospheric air: Potential vorticity: |PV| > 2 pvu, potential temperature: theta > 380K, specific humidity q < 0.1 g / kg, the connectivity of grid points with |PV| > 2 pvu to the stratosphere or the ground; Use the 3D tagging algorithm program for the fifth-generation atmospheric reanalysis dataset of global climate to calculate the tropopause folding frequency in different regions and different periods, including the following sub-steps: S2.

1. Based on the criteria for distinguishing stratospheric air, assign labels from 1 to 5 to the atmosphere of each grid point. Label 1: Tropospheric air; Label 2: Stratospheric air; Label 3: PV anomaly air generated by stratospheric truncation; Label 4: PV anomaly air generated by tropospheric truncation; Label 5: PV anomaly air generated by terrain change; S2.

2. For each region, in the vertical direction, from high altitude vertically downwards, if the change in air labels shows a conversion of 2->1->2->1 or 2->1->2->3, it is identified as a tropopause folding phenomenon, and the hourly folding label for this region f = 1. If no tropopause folding phenomenon is identified, the folding label f = 0; S2.

3. Calculate the daily tropopause folding frequency of each region as follows: ， Among them, f is the tropopause folding label for each hour in each region; S3. According to the stratospheric ozone tracer pulse quantity in the troposphere of the target area and the long-term time series of the daily average of the tropopause folding frequency in different regions, calculate the correlation and confidence interval between the stratospheric ozone tracer pulse quantity in the target area and the time change series of the tropopause folding frequency in each region, and determine the long-term high-frequency source area of the stratosphere that affects the tropospheric ozone in the target area; S4. According to the correlation and confidence interval between the stratospheric ozone tracer pulse quantity offset by the preset number of days in the target area and the tropopause folding frequency in each region, determine the transmission path of stratospheric ozone intrusion.

2. The method for tracing the stratospheric intrusion affecting tropospheric ozone pollution according to claim 1, wherein In step S3, when calculating the correlation between the stratospheric ozone tracer pulse quantity in the target area and the time change series of the tropopause folding frequency in each region, specifically calculate the Pearson correlation coefficient r as follows: ， In the formula, is the i-th value of variable X, where X is the pulsation of the stratospheric ozone tracer in the target area, is the average value of variable X, is the i-th value of variable Y, where Y is the time series of the tropopause folding frequency in each area, is the average value of variable Y.

3. A method for tracing the source of stratospheric intrusion affecting tropospheric ozone pollution according to claim 2, characterized in that, When calculating the confidence interval between the ozone in the target area and the time change series of the tropopause folding frequency in each region, specifically calculate the P value as follows: ， where t is the test statistic, and n represents the total number of time series data points used for correlation analysis, T df is the cumulative distribution function of the t-distribution.

4. A method for tracing the stratospheric intrusion affecting tropospheric ozone pollution according to claim 3, characterized in that, In step S3, screen the grid points with a correlation coefficient greater than 0.2 and a P value less than 0.1, determine them as the long-term high-frequency source area of the stratosphere that affects the tropospheric ozone in this region, and output their longitude and latitude at the same time.

5. An electronic device, comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the method described in any one of claims 1 to 4.

6. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the method described in any one of claims 1 to 4.

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