An intercalibrated dataset of Total Column Water Vapour and Wet Tropospheric Correction based on MWR on board ERS-1, ERS-2 and Envisat
Ralf Bennartz1,2, Heidrun Höschen3, Bruno Picard4, Marc Schröder3, Martin Stengel3, Oliver Sus3, Bojan Bojkov5,a, Stefano Casadio5, Hannnes Diedrich6, Salomon Eliasson7, Frank Fell8, Jürgen Fischer6, Rainer Hollmann3, Rene Preusker6, and Ulrika Willén71Earth & Env. Science Department, Vanderbilt University, Nashville, TN, USA 2Space Science and Engineering Center, University of Wisconsin- Madison, USA 3German Meteorological Service (DWD), Offenbach, Germany 4Collecte Localisation Satellite (CLS), Toulouse, France 5European Space Agency (ESA-ESRIN), Frascati, Italy 6Institute for Space Sciences, Freie Universität Berlin, Germany 7Swedish Meteorological and Hydrological Institute (SMHI), Norrköping, Sweden 8Informus GmbH, Berlin, Germany anow at: EUMETSAT, Darmstadt, Germany
Received: 17 Sep 2016 – Accepted for review: 13 Oct 2016 – Discussion started: 19 Oct 2016
Abstract. The Microwave Radiometers (MWR) on-board ERS-1, ERS-2, and Envisat provide a continuous time series of brightness temperature observations between 1991 and 2012. Here we report on a new Total Column Water Vapour (TCWV) and Wet Tropospheric Correction (WTC) dataset that builds on this time series. We use a one-dimensional variational approach to derive TCWV from MWR observations and ERA-Interim background information. A particular focus of this study lies on the intercalibration of the three different instruments, which is performed using constraints on liquid water path (LWP) and TCWV. Comparing our MWR-derived time series of TCWV against TCWV derived from Global Navigation Satellite System (GNSS) we find that the MWR-derived TCWV time series is stable over time. However, observations potentially affected by precipitation show a degraded performance compared to precipitation-free observations in terms of the accuracy of retrieved TCWV. An analysis of WTC shows further that the retrieved WTC is superior to purely model-derived WTC for all satellites and for the entire time series. Even compared to operational WTC retrievals, which incorporate additional observational data, the here-described dataset shows improvements in particular for the mid-latitudes and for the two earlier satellites ERS-1 and ERS-2. The dataset is publicly available under doi:10.5676/DWD_EMIR/V001.
Bennartz, R., Höschen, H., Picard, B., Schröder, M., Stengel, M., Sus, O., Bojkov, B., Casadio, S., Diedrich, H., Eliasson, S., Fell, F., Fischer, J., Hollmann, R., Preusker, R., and Willén, U.: An intercalibrated dataset of Total Column Water Vapour and Wet Tropospheric Correction based on MWR on board ERS-1, ERS-2 and Envisat, Atmos. Meas. Tech. Discuss., doi:10.5194/amt-2016-304, in review, 2016.