OFFL/L3_HCHO
This dataset provides offline high-resolution imagery of atmospheric formaldehyde (HCHO) concentrations.
Formaldehyde is an intermediate gas in almost all oxidation chains of non-methane volatile organic compounds (NMVOC), leading eventually to CO2. Non-Methane Volatile Organic Compounds (NMVOCs) are, together with NOx, CO and CH4, among the most important precursors of tropospheric O3. The major HCHO source in the remote atmosphere is CH4 oxidation. Over the continents, the oxidation of higher NMVOCs emitted from vegetation, fires, traffic and industrial sources results in important and localized enhancements of the HCHO levels. The seasonal and inter-annual variations of the formaldehyde distribution are principally related to temperature changes and fire events, but also to changes in anthropogenic activities. HCHO concentrations in the boundary layer can be directly related to the release of short-lived hydrocarbons, which mostly cannot be observed directly from space. [More information]
OFFL/L3_HCHO
该数据集提供了大气甲醛 (HCHO) 浓度的离线高分辨率图像。
甲醛是几乎所有非甲烷挥发性有机化合物 (NMVOC) 氧化链中的中间气体，最终会导致 CO2。非甲烷挥发性有机化合物 (NMVOC) 与 NOx、CO 和 CH4 一起，是对流层 O3 最重要的前体。偏远大气中的主要 HCHO 来源是 CH4 氧化。在各大洲，植被、火灾、交通和工业源排放的较高 NMVOC 的氧化导致 HCHO 水平的重要和局部提高。甲醛分布的季节性和年际变化主要与温度变化和火灾事件有关，但也与人为活动的变化有关。边界层中的 HCHO 浓度可能与短寿命碳氢化合物的释放直接相关，而这些碳氢化合物大多无法直接从太空中观察到。 [更多信息]
Dataset Availability
2018-12-05T12:14:36 - 2021-09-04T00:00:00
Dataset Provider
Collection Snippet
ee.ImageCollection("COPERNICUS/S5P/OFFL/L3_HCHO")
Resolution
0.01 degrees
Bands Table
| Name | Description | Min* | Max* | Units |
| tropospheric_HCHO_column_number_density | Tropospheric HCHO column number density. | -0.0172 | 0.0074 | mol/m^2 |
| tropospheric_HCHO_column_number_density_amf | Tropospheric air mass factor. | 0.177 | 4.058 | mol/m^2 |
| HCHO_slant_column_number_density | HCHO slant column number density. | -0.01425 | 0.00735 | mol/m^2 |
| 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 | 66.57 | 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. | 8.76 | 101.17 | degrees |
* = Values are estimated
| Name | Type | Description |
| ALGORITHM_VERSION | String | The algorithm version used in L2 processing. It's separate from the processor (framework) version, to accommodate different release schedules for different products. |
| BUILD_DATE | String | The date, expressed as milliseconds since 1 Jan 1970, when the software used to perform L2 processing was built. |
| HARP_VERSION | Int | The version of the HARP tool used to grid the L2 data into an L3 product. |
| INSTITUTION | String | The institution where data processing from L1 to L2 was performed. |
| L3_PROCESSING_TIME | Int | The date, expressed as milliseconds since 1 Jan 1970, when Google processed the L2 data into L3 using harpconvert. |
| LAT_MAX | Double | The maximum latitude of the asset (degrees). |
| LAT_MIN | Double | The minimum latitude of the asset (degrees). |
| LON_MAX | Double | The maximum longitude of the asset (degrees). |
| LON_MIN | Double | The minimum longitude of the asset (degrees). |
| ORBIT | Int | The orbit number of the satellite when the data was acquired. |
| PLATFORM | String | Name of the platform which acquired the data. |
| PROCESSING_STATUS | String | The processing status of the product on a global level, mainly based on the availability of auxiliary input data. Possible values are "Nominal" and "Degraded". |
| PROCESSOR_VERSION | String | The version of the software used for L2 processing, as a string of the form "major.minor.patch". |
| PRODUCT_ID | String | Id of the L2 product used to generate this asset. |
| PRODUCT_QUALITY | String | Indicator that specifies whether the product quality is degraded or not. Allowed values are "Degraded" and "Nominal". |
| SENSOR | String | Name of the sensor which acquired the data. |
| SPATIAL_RESOLUTION | String | Spatial resolution at nadir. For most products this is `3.5x7km2`, except for `L2__O3__PR`, which uses `28x21km2`, and `L2__CO____` and `L2__CH4___`, which both use `7x7km2`. This attribute originates from the CCI standard. |
| TIME_REFERENCE_DAYS_SINCE_1950 | Int | Days from 1 Jan 1950 to when the data was acquired. |
| TIME_REFERENCE_JULIAN_DAY | Double | The Julian day number when the data was acquired. |
| TRACKING_ID | String | UUID for the L2 product file. |
CLOSEIMPORT
代码：
var collection = ee.ImageCollection('COPERNICUS/S5P/NRTI/L3_HCHO') .select('tropospheric_HCHO_column_number_density') .filterDate('2019-06-01', '2019-06-06'); var band_viz = { min: 0.0, max: 0.0003, palette: ['black', 'blue', 'purple', 'cyan', 'green', 'yellow', 'red'] }; Map.addLayer(collection.mean(), band_viz, 'S5P HCHO'); Map.setCenter(0.0, 0.0, 2);
影像：
