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Introduction

The Sentinel-5 Precursor (Sentinel-5P) polar orbiting satellite is an active European Space Agency Earth observation platform that is funded under the European Commission's Copernicus Earth Observation Programme. It orbits the Earth 14 times a day.

Sentinel-5P carries the TROPOspheric Monitoring Instrument (TROPOMI) spectrometer. This instrument senses ultraviolet (UV), visible (VIS), near (NIR) and short-wave infrared (SWIR). Output from these sensors are used to generate products to monitor ozone, methane, formaldehyde, aerosol, carbon monoxide, nitrogen dioxide and sulphur dioxide in the atmosphere. These products are known as level 2 products.

TROPOMI takes measurements covering an area of 2600km by 7km. The satellite was launched in October 2017 and entered into routine operational phase in March 2019. Data is available from July 2018 onwards. The Sentinel-5P programme is an active and developing mission, from time to time ESA reprocesses data in order to take into account new scientific insights and operational developments.

Official ESA Documents

Technical documents for the Level 2 products consist of the following types:

  • PUM (Product User Information): The technical characteristics of the Level 2 products.
  • ATBD (Algorithm Theoretical Basis Document): detailed information on the retrieval algorithms.
  • IODD (Input Output Data definition): description of the input and output data of the S5P/TROPOMI Level 2 processing.

These documents and more can be found at the S5-P Document Library

Types of Data Contained in the MEEO-S5P Bucket

This data set consists of the Level 2 products generated from observations from the Sentinel-5P satellite. The Sentinel data is divided by type, described below:

  • Near Real Time (NRTI): Products are available within 3 hours of sensing, shortly after that they will appear in the S3 bucket. These files are in the netCDF file format. Over time NRTI data gets replaced by OFFL data. NRTI from 2020 onwards are converted to COG.
  • Off Line (OFFL): For level 2 products this data is available about a week after the NRTI data, shortly afterwards they will appear in the S3 bucket. These files are in the netCDF file format and are of higher quality to the NRTI data.
  • Reprocessed File (RPRO): From time to time there are new advances in product generation and ESA issues reprocessed files. These files are in the netCDF file format and are converted into cloud optimised geo-tiff by MEEO.
  • Cloud Optimised Geo-TIFF (COGT): These files are generated by MEEO from NRTI, OFFL and RPRO data shortly after the official Sentinel-5P data becomes available. These files are in the TIFF image file format.

The bucket, s3://meeo-s5p, will keep in step with ESA changes and updates to their published S5P Level 2 data set, if you would like to be kept up to date on how such changes effect the bucket contents please email here to be added to our mailing list (sentinel5p@meeo.it).

This bucket contains the following S5P Level 2 products:

Parameter Product Type (10 Characters wide) Parameter used to generate COGT
Ozone (O3) total column L2__O3____ ozone_total_vertical_column
Nitrogen Dioxide (NO2) L2__NO2___ nitrogendioxide_tropospheric_column
Sulphur Dioxide (SO2) total column L2__SO2___ sulfur_total_vertical_column_1k
Carbon Monoxide (CO) total column L2__CO____ carbonmonoxide_total_column
Methane (CH4) total column L2__CH4___ methane_mixing_ratio
Formaldehyde (HCHO) total column L2__HCHO__ formaldehyde_tropospheric_vertical_column
UV Aerosol Index L2__AER_AI aerosol_index_354_388

File Names and Path Structure of Bucket

File Names

NRT and OFFL files retain their original filenames. The file names vary based on the parameter, but the general naming schema is a as follows:

MMM_XXXX_PPPPPPPPPP_YYYYMMDDTHHMMSS_YYYYMMDDTHHMMSS_ORBIT_NN_Mmmmpp_YYYYMMDDTHHMMSS.nc

Where:

  • MMM (3 characters): mission name (S5P).

  • XXXX (4 characters): processing stream (NRTI, OFFL, RPRO).

  • PPPPPPPPPP (10 characters): Product identifier.

  • YYYYMMDDTHHMMSS (15 characters): Start of acquisition time (note T is a fixed character).

  • YYYYMMDDTHHMMSS (15 characters): End of acquisition time (note T is a fixed character).

  • Orbit (5 characters): Orbit Number.

  • NN (2 characters): Collection number.

  • MMmmpp (5 characters): Processor number, with “MM” the major version number, “mm” the minor version number and “pp” as the patch level.

  • YYYYMMDDTHHMMSS (15 characters): the data processing time (note T is a fixed character).

  • NC (2 characters): the file name extension. File formats are netCDF-4 there the extension will be “nc”

For example:

S5P_OFFL_L2__NO2____20191001T012402_20191001T030531_10182_01_010302_20191007T032229.nc

Bucket structure and constructing a path to a file

The bucket name is:

  • s3://meeo-s5p

A directory structure has been added to help with data discovery. This directory structure is based on the filename and is as follows:

  • MMM: mission name (S5P)
  • XXXX: processing stream (NRTI, OFFL, COGT)
  • PPPPPPPPPP: Product identifier
  • YYYY: Acquisition. year
  • MM: Acquisition. month
  • DD: Acquisition. Day

For example, to construct the path to the file below:

S5P_OFFL_L2__NO2____20191001T012402_20191001T030531_10182_01_010302_20191007T032229.nc

  1. Start with the S3 bucket section: meeo-s5p/OFFL/

  2. Then get the path to the directory: /L2__NO2___/2019/10/01/

  3. This gives the path: meeo-s5p/OFFL/L2__NO2___/2019/10/01/

  4. Now append the file name to directory path to get the path to the file: meeo-s5p/OFFL/L2__NO2___/2019/10/01/

Finally we have a path to the desired file:

s3://meeo-s5p/OFFL/L2__NO2___/2019/10/01/S5P_OFFL_L2__NO2____20191001T012402_20191001T030531_10182_01_010302_20191007T032229.nc

Cloud Optimised Geo-TIFF

Geo-Tiffs are image files that have been generated from the original netCDF files.

The paths to the geo-tiff files and the file names are constructed as follows:

NB: The paths for COGT are slightly different from previous paths.

  1. Start with the S3 bucket section, use COGT and then NRTI or OFFL: meeo-s5p/COGT/OFFL/

  2. Then get the path to the directory, this will be the same construction as the original file that the TIFF is generated from. Note: /L2__NO2___/2019/10/01/

  3. This gives the path: meeo-s5p/COGT/OFFL/L2__NO2___/2019/10/01/

  4. Now append the file name to directory path to get the path to the file: meeo-s5p/COGT/OFFL/L2__NO2___/2019/10/01/

  5. Prepare the file name, append the appropriate parameter to original filename and replace .nc file ending with .tif

     S5P_OFFL_L2__NO2____20191001T012402_20191001T030531_10182_01_010302_20191007T032229.nc
     
     becomes
     
     S5P_OFFL_L2__NO2____20191001T012402_20191001T030531_10182_01_010302_20191007T032229_nitrogendioxide_tropospheric_column.tif
    

SpatioTemporal Asset Catalog (STAC)

MEEO have implemented a SpatioTemporal Asset Catalog for this data archive. The catalogue is updated daily. You can read more about STAC here.