The Sentinel-5p TROPOMI L2 CH4 data product (dry air averaged methane column) is in good overall agreement with correlative ground-based measurements from NDACC and TCCON. Bias and dispersion estimates (see Table below) meet mission requirements.
|Product ID||Stream||Product||Bias||Dispersion||Special features|
|L2_CH4||RPRO/OFFL||xCH4||-0.25%||0.6%||Along orbit stripes.
Underestimation at low albedo. Remaining outliers with qa_value >0.5.
1-4% seasonal and SZA dependence of bias. Lower number of pixels
with qa_value>0.5 between March 11 2020 and July 1 2021 due to changed cloud data.
The averaged correlation coefficient is 0.65 for the TCCON network
Plots show the weekly mean relative differences for the S5P RPRO/OFFL xCH4 columns against TCCON (top) and NDACC (bottom) sites. Sites are sorted by decreasing latitude.
For more information please consult the latest issue of the Sentinel-5p Routine Operations Consolidated Validation Report (ROCVR).
|Latest Quarterly Validation Report||Product info||Current Processor Version|
|#13: April 2018 - December 2021||See sentinel.esa.int||
Details of the validation setup can be found in the latest quarterly validation report and in Sha, M. K., et al.: Validation of methane and carbon monoxide from Sentinel-5 Precursor using TCCON and NDACC-IRWG stations, Atmos. Meas. Tech., 14, 6249–6304, https://doi.org/10.5194/amt-14-6249-2021, 2021
NDACC is a cross-border international research network of remote sounding stations. It is a major contributor to the World Meteorological Organisation (WMO) GAW programme and it works under the auspices of United Nations Environment Programme (UNEP) and the International Ozone Commission (IO3C). At present time it includes more than 70 high-quality, remote-sensing research stations/sites distributed worldwide. Within the MPC VDAF we rely on the NDACC FTIR CH4 measurement data which provide vertical CH4 concentration profiles with a limited vertical resolution.
The Total Carbon Column Observing Network (TCCON), established in 2004, is a network of ground- based Fourier Transform Spectrometers that measures column-averaged abundances of atmospheric constituents including CO2, xCH4, N2O, HF, CO, H2O, and HDO. TCCON was included in the Global Atmosphere Watch (GAW) of the WMO in 2009.
NDACC and TCCON sites
The Sentinel-5p Mission Performance Centre provides an operational validation service relying on the VDAF Automated Validation Server (VDAF-AVS). This fully automated data analysis system collects correlative measurements from quality-controlled monitoring networks and compares them to Sentinel-5p data using community endorsed protocols. It outputs a suite of traceable quality indicators enabling users to judge the fitness-for-purpose of the Sentinel-5p data.
The illustration given hereafter shows the automated comparison of Sentinel-5p xCH4 column data with respect to correlative measurements aquired by an FTIR instrument of the NDACC network. More methane validation results are available at http://mpc-vdaf-server.tropomi.eu/ch4
Quarterly Validation Report of the Copernicus Sentinel-5 Precursor Operational Data Products #13: April 2018 - December 2021
Previous issues of the quarterly validation report are archived here.