TROPOMI¶

Copernicus Sentinel-5 Precursor TROPOspheric Monitoring Instrument (TROPOMI) Level 2 products (NO2, CO, CH4, SO2, HCHO, O3, aerosols and other atmospheric composition swath data)

Available

At a glance¶

Note on period: Operational L2 starts on 2018-04-30 (the RPRO 02.04.00 covers 2018-04-30 to 2022-07-25). From 2019-08-06 (orbit 9388) the along-track pixel size shrank from 7 km to 5.5 km. As checked on 2026-10-13, the latest NO2 OFFL file at GES DISC is for 2026-10-02, and CDSE keeps NRTI data for the last month only.

Overview¶

TROPOMI is a UV–visible–near-infrared–shortwave-infrared imaging spectrometer on the Copernicus Sentinel-5 Precursor satellite. Since 2018 it has observed nitrogen dioxide (NO2), carbon monoxide (CO), methane (CH4), sulphur dioxide (SO2), formaldehyde (HCHO), ozone, aerosol index and layer height, and clouds with near-global daily coverage. Its 5.5 × 3.5 km pixels, far smaller than OMI's, make it a workhorse for air quality and greenhouse gas analyses down to individual cities, power plants and other sources, and it is the central record of afternoon-orbit atmospheric composition following OMI.

What changes with the successor¶

TROPOMI processor V1 (01.xx) → TROPOMI processor V2 (02.xx) + full-mission reprocessing (RPRO 02.04.00)¶

Transition: 2021-07

In July 2021 the processors moved to 02.xx and the dataset version became V2 (with new DOIs); version 02.04.00, operational from July 2022, was used to reprocess (RPRO) the record from mission start to July 2022. Each NO2 switch, 1.4.0 (2020-12) and 2.2.0 (2021-07), substantially raised tropospheric columns over polluted areas, so time series that mix processor versions show steps.

Sources: S5P NO2 Product Readme File (issue 2.8, 2025-03-19) · S5P CH4 Product Readme File (2025, 2.8) · TROPOMI data products — nitrogen dioxide (version and DOI table)

Available variables¶

Names as given in each product's Product Readme File (PRF) and Product User Manual (PUM); all sit in the PRODUCT group of the netCDF-4 files. Columns are in SI units (mol m-2); multiply by multiplication_factor_to_convert_to_molecules_percm2 (6.02214×10^19) for molecules cm-2. Every product has a qa_value quality indicator (0–1).

instantaneous mean accumulated maximum minimum static — instantaneous: value at the time stamp · mean/accumulated/maximum/minimum: over the indicated interval · static: does not change with time

Trace gas columns (L2 swath)¶

Ozone, aerosol and cloud products¶

Quality and time¶

The full variable list is in the official documentation.

How to get the data¶

• Copernicus Data Space Ecosystem (CDSE) — Web browser, OData, STAC, S3, openEO (collection SENTINEL-5P)
  • A free CDSE account is required. Product type codes include L2__NO2___, L2__CO____, L2__CH4___, L2__SO2___, L2__HCHO__, L2__O3____, L2__AER_AI and L2__CLOUD_. Offline data are available from April 2018; NRTI is kept for the last month only.
• CDSE Sentinel-5P documentation (product list, OData examples) — Web documentation
• NASA GES DISC (Earthdata redistribution) — HTTPS, earthaccess, OPeNDAP (NASA Earthdata Login)
  • Collections include S5P_L2__NO2____HiR, S5P_L2__CO_____HiR, S5P_L2__CH4____HiR, S5P_L2__SO2____HiR, S5P_L2__HCHO___HiR, S5P_L2__AER_AI_HiR and S5P_L2__O3_TOT_HiR (version 2). Convenient alongside NASA tools such as earthaccess and Giovanni.

Example code¶

Downloads the GES DISC copy with earthaccess and opens the PRODUCT group with xarray. Files from CDSE have the same structure.

# pip install earthaccess xarray netCDF4
import earthaccess
import xarray as xr

earthaccess.login()
results = earthaccess.search_data(
    short_name="S5P_L2__NO2____HiR", version="2",
    temporal=("2025-03-01", "2025-03-01"),
    bounding_box=(124, 33, 132, 39),          # (west, south, east, north) — Korean Peninsula
)
files = earthaccess.download(results[:1], "./s5p")

ds = xr.open_dataset(files[0], group="PRODUCT")
no2 = ds["nitrogendioxide_tropospheric_column"].where(ds["qa_value"] > 0.75)   # mol m-2
no2_molec = no2 * 6.02214e19                                                    # molecules cm-2
print(float(no2_molec.mean()), ds["time_utc"].values[0, :2])

Practical tips¶

• qa_value thresholds differ by product. The default advice is above 0.75 for tropospheric and total NO2 (0.5 to include scenes over clouds and snow), and above 0.5 for stratospheric NO2, CO, CH4, SO2 and HCHO.
• Do not mix processor versions. The official advice for long-term work is RPRO (2018-04-30 to 2022-07-25) plus later OFFL, and small discontinuities have appeared at each switch since (2.6.0, 2.7.1, 2.8.0, 2.9.1).
• Pixel size changed on 6 August 2019 (along track 7 → 5.5 km). Take care with analyses that count samples by pixel.
• Do not delete negative columns over clean regions when averaging. They come from noise, and removing them biases the mean high (common advice in the SO2, HCHO and NO2 READMEs).
• Single HCHO and SO2 pixels are noisy, so they are usually gridded over days to a month. HCHO and SO2 2.8.0 data for 2025-11-22 to 12-02 (OFFL) had a striping problem and are to be reprocessed.
• The CH4 product has used Suomi NPP VIIRS cloud data as its primary cloud filter. NOAA and NASA have announced that Suomi NPP science data delivery ends in early November 2026, after which CH4 and aerosol layer height will rely on TROPOMI's own cloud masks (machine-learning mask since 2.6.0, the AER_LH fallback mask added in 2.9.1).
• For NO2 air quality comparisons remember that the satellite looks once, around 13–14 local time, and that a column is not a surface concentration (averaging kernels and a priori profiles differ). Applying the averaging kernels in the files is standard practice when comparing with models.
• When downloading from CDSE via Sentinel Hub or openEO, request only one product (band) at a time.

Notices and change history¶

References for your paper¶

Dataset citation¶

TROPOMI L2 NO2 V2 (OFFL and RPRO) — DOI 10.5270/S5P-9bnp8q8

@misc{s5p_no2_v2,
  author    = {{Copernicus Sentinel-5P (processed by ESA)}},
  title     = {{TROPOMI} Level 2 Nitrogen Dioxide total column products. Version 02},
  year      = {2021},
  publisher = {European Space Agency},
  doi       = {10.5270/S5P-9bnp8q8}
}

TROPOMI L2 CO V2 — DOI 10.5270/S5P-bj3nry0

@misc{s5p_co_v2,
  author    = {{Copernicus Sentinel-5P (processed by ESA)}},
  title     = {{TROPOMI} Level 2 Carbon Monoxide products. Version 02},
  year      = {2021},
  publisher = {European Space Agency},
  doi       = {10.5270/S5P-bj3nry0}
}

TROPOMI L2 CH4 V2 — DOI 10.5270/S5P-3lcdqiv

@misc{s5p_ch4_v2,
  author    = {{Copernicus Sentinel-5P (processed by ESA)}},
  title     = {{TROPOMI} Level 2 Methane products. Version 02},
  year      = {2021},
  publisher = {European Space Agency},
  doi       = {10.5270/S5P-3lcdqiv}
}

TROPOMI L2 HCHO V2 — DOI 10.5270/S5P-vg1i7t0

@misc{s5p_hcho_v2,
  author    = {{Copernicus Sentinel-5P (processed by ESA)}},
  title     = {{TROPOMI} Level 2 Formaldehyde Total Column products. Version 02},
  year      = {2020},
  publisher = {European Space Agency},
  doi       = {10.5270/S5P-vg1i7t0}
}

Reference papers¶

TROPOMI mission and instrument overview — DOI 10.1016/j.rse.2011.09.027

@article{veefkind2012tropomi,
  author  = {Veefkind, J. P. and Aben, I. and McMullan, K. and F{\"o}rster, H. and de Vries, J. and Otter, G. and Claas, J. and Eskes, H. J. and de Haan, J. F. and Kleipool, Q. and van Weele, M. and Hasekamp, O. and Hoogeveen, R. and Landgraf, J. and Snel, R. and Tol, P. and Ingmann, P. and Voors, R. and Kruizinga, B. and Vink, R. and Visser, H. and Levelt, P. F.},
  title   = {{TROPOMI} on the {ESA} Sentinel-5 Precursor: A {GMES} mission for global observations of the atmospheric composition for climate, air quality and ozone layer applications},
  journal = {Remote Sensing of Environment},
  volume  = {120},
  pages   = {70--83},
  year    = {2012},
  doi     = {10.1016/j.rse.2011.09.027}
}

Acknowledgements¶

The TROPOMI website recommends citing each product and version as 'Copernicus Sentinel-5P (processed by ESA), year, product name. Version 02. European Space Agency. DOI'. The SO2 V2 DOI is 10.5270/S5P-74eidii (per the GES DISC collection record). If you used data from the V1 period (processors 01.xx, before July 2021), cite the V1 DOI (for NO2, 10.5270/S5P-s4ljg54) and also cite each product's ATBD for the algorithm. If you obtained the data from GES DISC, say so.

Information on the datasets used in this study was compiled with the help of the Korean Climate Data Navigator (KCDN) (Sim, 2026; https://doi.org/10.5281/zenodo.23300923).

Links¶

• TROPOMI official site — L2 products
• SentiWiki — S5P products (per-product Readme, PUM, ATBD)
• SentiWiki — S5P mission
• CDSE news (S5P processor and data gap notices)
• ESA — Copernicus Sentinel-5 (MetOp-SG)
• EUMETSAT — CO2M