Sentinel-5 Precursor (5P) is a low Earth orbit polar satellite mission dedicated to monitoring air pollution. The satellite carries the state-of-the-art TROPOspheric Monitoring Instrument (TROPOMI). With TROPOMI, Sentinel-5P images air pollutants more accurately and at a higher spatial resolution than any other spaceborne instrument.This service provides daily global composite images of tropospheric nitrogen dioxide measurements. The presence of Nitrogen Dioxide (NO2) has direct negative respiratory effects and contributes to the formation and modification of other air pollutants, such as ozone and particulate matter. The Sentinel-5P NO2 data products pose an improvement over previous data sets, particularly in their unprecedented spatial resolution, but also in the separation of the stratospheric and tropospheric contributions of the retrieved slant columns, and in the calculation of the air-mass factors used to convert slant to total columns. More...Key PropertiesSpatial CoverageGlobalTemporal Coverage01-Nov-2018 to PresentSpatial Resolution5 x 5 KmTemporal ResolutionDailyImagery is collected globally each day. However, multi-day gaps can occur between collection and actual data availability. New daily global Level 3 composites are created each day with the latest publicly available Level 2 data.Days with any missing strips are omitted from this layer.Product LevelLevel 3Units/Physical Quantitymol/m²Tropospheric ColumnTypical Value Range0 - 0.0003 mol/m² (0 - 300 μmol/m²)Peak values for polluted cities may reach two or three times the upper value.Layer ConfigurationThe default rendering is a colorized rolling 7-day mean. This is applied with the "Colorized Nitrogen Dioxide (NO2) in Micromoles Per Meter Squared" processing template, plus a layer definition query to select the most recent 7 days available ('Best' < 8).The default mosaic operator is "mean" or "average of all pixels". In practice, this means that unless a user has locked on to a single day/image, the values returned will be the mean for all images displayed. Layer filtering/definition queries can be used to customize your timeframe of interest. If no definition query is included on the layer, a mean for the latest 31 days will be displayed.It is important to note that display performance correlates with number if images. It will take longer to render a 31-day mean than is does for a 7-day mean.Users can temporally select/group data by either the 'AcquisitionDate' or 'Best' fields/attributes.The 'Best' field grades each item in the Image Service based on its recentness within the product's record. The most recent daily data is given the lowest values while the oldest daily data gets the highest values.Level 3 Processing OverviewThe original Sentinel-5P Level 2 data from the European Space Agency has been re-gridded and merged to create a single Level 3 Cloud Optimized GeoTiff for each day of collection for each product. The software package HARP-Convert has been used to merge and re-grid the data in order to keep a single grid per orbit (that is, no aggregation across products is performed). The complete conversion to Level 3 using HARP-Convert utilizes the "bin_spatial" operation that spatially averages pixel values between overlapping scenes for a given day of collection. In addition to the merging operation, HARP Convert is used to filter pixel values for quality as well as other variables depending on product. After the merging and regridding process, OptimizeRasters is invoked to create a Level 3 Cloud Optimized GeoTiff for a given day's worth of data for each product.