The Sentinel 5-P(Precursor) is part of the Copernicus Earth Observation Programme. Copernicus is coordinated and managed by the European Commision. It's main objective is to globally monitor key air quality trace gases and aerosols in support of Copernicus Atmosphere Monitoring Service (CAMS) at a high spatial resolution and a daily global revisit time.
The products are based on daily means at European level based on offline products (OFFL) at level 3 from Google Earth Engine. Level 3 from Google Earth Engine (GEE) is Level 2 data that was processed to be ingested in GEE more easily. The OFFLINE products were used instead of the NearRealTIme (NRTI) products because those are using actual TM5-MP analysis data and not forecasted, like NRTI data. TM5-MP is a global chemistry transport model employed for deriving highly resolved vertical profiles in retrievals of various gases with different satellites platforms (Ozone Monitoring Instrument-OMI and Tropospheric Monitoring Instrument-TROPOMI).
With a daily revisiting time and a spatial native resolution of 3.5x7km, resampled to 5x5 km, TROPOMI represents the best solution for monitoring trace gases from the athmosphere.
The present includes 4 trace gases : Methane(CH₄), Nitrogen Dioxide (NO₂), Carbon Monoxide (CO) and Sulphur Dioxide(SO₂).
Methane it's a potent greenhouse gas, trapping about 35 times more heat than carbon dioxide.( https://earthdata.nasa.gov/learn/articles/methane-fossil-fuel-exploitation). Roughly three-quarters of methane emissions are anthropogenic and as such it is important to continue the record of satellite based measurements (http://www.tropomi.eu/data-products/methane). Sentinel 5P measures CH₄ total column as part of the air mixing ratio, in parts per bilion volume (ppbv).
Nitrogen Dioxide it's an import trace gase present in troposhpere and also in stratosphere. It's main formed mainly as a cause of human activities (biomass burning or fuel consumption), but also natural causes. The TROPOMI NO₂ processing system is based on the algorithm developments for the DOMINO-2 product and for the EU QA4ECV NO2 reprocessed dataset for OMI, and has been adapted for TROPOMI. (http://www.tropomi.eu/data-products/nitrogen-dioxide) Sentinel 5P measures NO₂ as tropospheric, stratospheric and total column vertical distribution in mol/m². This application represents NO₂ as μmol/m².
Carbon Monoxide it's a major atmospheric pollutant, resulting especially in burning of fossil fuels, biomass and in athmosperic oxidation. At Northren mid-latitudes the main source of CO is the fossil fuel burning (more industrialized countries and bigger economies), on the other hand at tropics a important role is taken from biomass burning and oxidation of isoprene. Sentinel 5P measures CO values as column vertical distribution in mol/m². This application represents CO as molecules/cm².
Sulphur Dioxide plays a importan role in global atmosphere chemistry, as well at a local level. Only 30% of SO₂ accounts for natural sources (mostly volcanic emmisions) and the rest is a result of anthropogenic industrial activities and burning of fossil fuels. Short term exposures to high concentrations of SO₂ can have harmful effects on human health. SO₂ vertical column density is computed at ground level, using the Differential Optical Absorption Spectroscopy technique (DOAS) and is expressed in mol/m². Because most of the applications and graphic representations of SO₂ use Dobson Units (DU) as measurement unit, also this application uses DU.