数据简介：
OFFL/L3_SO2
This dataset provides offline high-resolution imagery of atmospheric sulfur dioxide (SO2) concentrations.
Sulphur dioxide (SO2) enters the Earth’s atmosphere through both natural and anthropogenic processes. It plays a role in chemistry on a local and global scale and its impact ranges from short-term pollution to effects on climate. Only about 30% of the emitted SO2 comes from natural sources; the majority is of anthropogenic origin. SO2 emissions adversely affect human health and air quality. SO2 has an effect on climate through radiative forcing, via the formation of sulphate aerosols. Volcanic SO2 emissions can also pose a threat to aviation, along with volcanic ash. S5P/TROPOMI samples the Earth’s surface with a revisit time of one day with unprecedented spatial resolution of 3.5 x 7 km which allows the resolution of fine details including the detection of much smaller SO2 plumes. [More information]
For this L3 SO2 product, the absorbing_aerosol_index is calculated with a pair of measurements at the 340 nm and 380 wavelengths. The COPERNICUS/S5P/OFFL/L3_AER_AI product has the absorbing_aerosol_index calculated using the 354 nm and 388 nm wavelengths.
OFFL/L3_SO2
该数据集提供大气中二氧化硫（SO2）浓度的离线高分辨率图像。
二氧化硫（SO2）通过自然和人为的过程进入地球的大气层。它在地方和全球范围内的化学中起着作用，其影响范围从短期污染到对气候的影响。只有大约30%的二氧化硫排放来自于自然来源；大部分是人为的。二氧化硫的排放对人类健康和空气质量有不利影响。二氧化硫通过硫酸盐气溶胶的形成，通过辐射强迫对气候产生影响。火山SO2排放与火山灰一起也会对航空构成威胁。S5P/TROPOMI对地球表面进行采样，重访时间为一天，具有前所未有的3.5 x 7公里的空间分辨率，这使得对细微细节的分辨率包括对更小的SO2羽流的探测。[更多信息］
对于这个L3 SO2产品，吸收_气溶胶指数是用340纳米和380波长的一对测量值计算的。COPERNICUS/S5P/OFFL/L3_AER_AI产品的吸收气溶胶指数是用354纳米和388纳米波长计算的。
Dataset Availability
2018-12-05T11:53:01 -
Dataset Provider
Collection Snippet
ee.ImageCollection("COPERNICUS/S5P/OFFL/L3_SO2")
Resolution
1113.2 meters
Bands Table
| Name | Description | Min* | Max* | Units |
| SO2_column_number_density | SO2 vertical column density at ground level, calculated using the DOAS technique. | -0.4051 | 0.2079 | mol/m^2 |
| SO2_column_number_density_amf | Weighted mean of cloudy and clear air mass factor (amf) weighted by intensity-weighted cloud fraction. | 0.1 | 3.387 | mol/m^2 |
| SO2_slant_column_number_density | SO2 ring corrected slant column number density | -0.14746 | 0.16159 | mol/m^2 |
| absorbing_aerosol_index | A measure of the prevalence of aerosols in the atmosphere, calculated by [this equation](https://earth.esa.int/web/sentinel/technical-guides/sentinel-5p/level-2/aerosol-index) using the 340/380 wavelength pair. | -11.733 | 18.657 | |
| cloud_fraction | Effective cloud fraction. See the [Sentinel 5P L2 Input/Output Data Definition Spec](https://sentinels.copernicus.eu/documents/247904/3119978/Sentinel-5P-Level-2-Input-Output-Data-Definition), p.220. | 0 | 1 | fraction |
| sensor_azimuth_angle | Azimuth angle of the satellite at the ground pixel location (WGS84); angle measured East-of-North. | -180 | 180 | degrees |
| sensor_zenith_angle | Zenith angle of the satellite at the ground pixel location (WGS84); angle measured away from the vertical. | 0.098 | 67 | degrees |
| solar_azimuth_angle | Azimuth angle of the Sun at the ground pixel location (WGS84); angle measured East-of-North. | -180 | 180 | degrees |
| solar_zenith_angle | Zenith angle of the satellite at the ground pixel location (WGS84); angle measured away from the vertical. | 8 | 102 | degrees |
| SO2_column_number_density_15km | SO2 vertical column density at 15km, calculated using the DOAS technique. | mol/m^2 |
* = Values are estimated
代码：
// 分别定义两年的影响数据筛选 var y2019 = ee.ImageCollection("COPERNICUS/S5P/OFFL/L3_SO2").filterDate("2019-02-01","2019-02-28"); var y2020 = ee.ImageCollection("COPERNICUS/S5P/OFFL/L3_SO2").filterDate("2020-02-01","2020-02-28"); //获取中国边界 var countries = ee.FeatureCollection("USDOS/LSIB_SIMPLE/2017").filter(ee.Filter.eq("country_co", "CH")) // 上色 var band_viz = { min: 0.0, max: 0.0005, palette: ['black', 'blue', 'purple', 'cyan', 'green', 'yellow', 'red'] }; //图层加载 Map.addLayer(y2019.max().select("SO2_column_number_density").clip(countries),band_viz," 2019"); Map.addLayer(y2020.max().select("SO2_column_number_density").clip(countries),band_viz," 2020");
结果：
图涉及中国区域没法展示，大家自己copy 代码去实现
