Sentinel-5P OFFL SO2: Offline Sulphur Dioxide Data (COPERNICUS/S5P/OFFL/L3_SO2)

###Sentinel-5 Precursor

Sentinel-5 Precursor is a satellite launched on 13 October 2017
by the European Space Agency to monitor air pollution. The onboard sensor
is frequently referred to as Tropomi (TROPOspheric Monitoring Instrument).

All of the S5P datasets have two versions: Near Real-Time (NRTI) and Offline
(OFFL). The NRTI assets cover a smaller area than the OFFL assets, but
appear more quickly after acquisition. The OFFL assets contain data
from a single orbit (which, due to half the earth being dark, contains
data only for a single hemisphere).

The original Sentinel 5P Level 2 (L2) data is binned
by time, not by latitude/longitude. To make it possible to ingest the data
into Earth Engine, each Sentinel 5P L2 product is converted to L3, keeping
a single grid per orbit (that is, no aggregation across products
is performed).

Source products spanning the antimeridian are ingested as two Earth Engine
assets, with suffixes _1 and _2.

The conversion to L3 is done by the harpconvert
tool using the bin_spatial operation. The source data is filtered to
remove any values with QA values of less than 50.


This dataset provides offline high-resolution imagery of atmospheric sulfur
dioxide (SO2) concentrations.

For this L3 SO2 product, the absorbing_aerosol_index is calculated with a
pair of measurements at the 340 nm and 380 wavelengths. The
product has the absorbing_aerosol_index calculated using the 354 nm and 388
nm wavelengths.

To make our OFFL L3 products, we find areas within the product’s bounding
box with data using a command like this:

harpconvert --format hdf5 --hdf5-compression 9
-a 'SO2_column_number_density_validity>50;derive(datetime_stop {time})'

We then merge all the data into one large mosaic (taking only one value for
pixels that may have different values for different times). From the
mosaic, we create a set of tiles containing orthorectified raster data.

Example harpconvert invocation for one tile:

harpconvert --format hdf5 --hdf5-compression 9
-a 'SO2_column_number_density_validity>50;derive(datetime_stop {time});
bin_spatial(2001, 50.000000, 0.01, 2001, -120.000000, 0.01);
     SO2_slant_column_number_density,absorbing_aerosol_index,cloud_fraction, sensor_altitude,
     sensor_azimuth_angle, sensor_zenith_angle,solar_azimuth_angle,
SO2_column_number_densitySO2 vertical column density, calculated using the DOAS technique. mol/m^2
SO2_column_number_density_amfWeighted mean of cloudy and clear air mass factor (amf) weighted by intensity-weighted cloud fraction. mol/m^2
SO2_slant_column_number_densitySO2 ring corrected slant column number densitymol/m^2
absorbing_aerosol_indexA measure of the prevalence of aerosols in the atmosphere, calculated by [this equation]( using the 340/380 wavelength pair.
cloud_fractionEffective cloud fraction. See the [Sentinel 5P L2 Input/Output Data Definition Spec](, p.220. fraction
sensor_azimuth_angleAzimuth angle of the satellite at the ground pixel location (WGS84); angle measured East-of-North. degrees
sensor_zenith_angleZenith angle of the satellite at the ground pixel location (WGS84); angle measured away from the vertical. degrees
solar_azimuth_angleAzimuth angle of the Sun at the ground pixel location (WGS84); angle measured East-of-North. degrees
solar_zenith_angleZenith angle of the satellite at the ground pixel location (WGS84); angle measured away from the vertical. degrees


European Union/ESA/Copernicus (producer, licensor)
Google Earth Engine (host)
STAC Version 0.6.2
Keywords TROPOMI, air_quality, bira, copernicus, dlr, esa, eu, pollution, s5p, sentinel, so2, sulfur_dioxide, sulphur_dioxide
License proprietary
Temporal Extent 12/5/2018, 3:53:01 AM - now
Type image_collection
GSD arc degreesm
Platform Sentinel-5P
Instrument TROPOMI
cube:dimensions {"x":{"type":"spatial","axis":"x","extent":[-180,180]},"y":{"type":"spatial","axis":"y","extent":[-90,90]},"temporal":{"type":"temporal","extent":["2018-12-05T11:53:01Z",null]},"bands":{"type":"bands","values":["SO2_column_number_density","SO2_column_number_density_amf","SO2_slant_column_number_density","absorbing_aerosol_index","cloud_fraction","sensor_azimuth_angle","sensor_zenith_angle","solar_azimuth_angle","solar_zenith_angle"]}}