SAF/WV_cci TCWV: Combined global total column water vapour product from microwave and near infrared imagers

BThe global total column water vapour (TCWV) data record combines microwave and near-infrared imager based TCWV over the ice-free ocean as well as over land, coastal ocean and sea-ice, respectively. The data record relies on microwave observations from SSM/I, SSMIS, AMSR-E and TMI, partly based on a fundamental climate data record (Fennig et al., 2020; Fennig et al., 2017) and on near-infrared observations from MERIS (3rd reprocessing), MODIS-Terra (collection 6.1) and OLCI (1st reprocessing). Details of the retrieval are described in Andersson et al. (2010) and ATBD HOAPS for the microwave imagers as well as in Lindstrot et al. (2012), Diedrich et al. (2015) and ATBD NIR Level 2 for the near-infrared imagers. The water vapour of the atmosphere is vertically integrated over the full column and given in units of kg/m². The microwave and near-infrared data streams are processed independently and combined afterwards by not changing the individual TCWV values and their uncertainties. The combined data record has a spatial resolution of 0.5°x0.5° and 0.05°x0.05°, with the near-infrared based data being averaged and the microwave-based data being oversampled to match the lower and higher spatial resolution, respectively. The product is available as daily and monthly means and covers the period July 2002 – December 2017

Global maps of daily TCWV in units of kg/m2 from the combined microwave and near-infrared imager data record: 1 July 2007 (left) and 1 July 2015 (right). Grey areas mark regions that are not observed by the satellites.

Acknowledgement:
The combined MW and NIR product was initiated and funded by the ESA Water_Vapour_cci project. The NIR retrieval was developed by Spectral Earth. The MW data was processed by EUMETSAT CM SAF. The NIR data was processed and combined with the MW data by Brockmann Consult. NIR data is owned by Brockmann Consult and Spectral Earth. The MW data and the combined MW and NIR product is owned by EUMETSAT CM SAF.

References:

• Diedrich, H., R. Preusker, R. Lindstrot, and J. Fischer: Retrieval of daytime total columnar water vapour from MODIS measurements over land surfaces. Atmospheric Measurement Techniques, 8:823-836, doi: 10.5194/amt-8-823-2015, 2015
• Eiras-Barca, Jorge, Iago Algarra, Raquel Nieto, Marc Schröder, Michaela I. Hegglin, Luis Gimeno: Analysis of the main source regions of moisture transport events with the new ESA CCI/CM-SAF total column water vapour climate data record (v2). Quarterly Journal of the Royal Meteorological Society, 1–15, doi: 10.1002/qj.4358, 2022
• Fennig, K.; Schröder, M.; Hollmann, R.: Fundamental Climate Data Record of Microwave Imager Radiances, Edition 3, Satellite Application Facility on Climate Monitoring, doi:10.5676/EUM_SAF_CM/FCDR_MWI/V003, 2017
• Fennig, K., Schröder, M., Andersson, A., and Hollmann, R.: A Fundamental Climate Data Record of SMMR, SSM/I, and SSMIS brightness temperatures, Earth Syst. Sci. Data, 12, 647–681, doi: 10.5194/essd-12-647-2020, 2020.
• He, J., Brogniez, H., and Picon, L.: Evaluation of tropical water vapour from CMIP6 global climate models using the ESA CCI Water Vapour climate data records, Atmos. Chem. Phys., 22, 12591–12606, doi: 10.5194/acp-22-12591-2022, 2022
• Lindstrot, R., R. Preusker, H. Diedrich, L. Doppler, R. Bennartz, and J. Fischer: 1D-Var retrieval of daytime total columnar water vapour from MERIS measurements. Atmospheric Measurement Techniques, 5: 631–646, doi: 10.5194/amt-5-631-2012, 2012

MS / Feb2023