ESA Water Vapour CCI User workshop



The Water Vapour Climate Change Initiative (WV_cci) is a project of the European Space Agency (ESA) with the overall goal to generate climate data records (CDRs) of atmospheric water vapour for use in climate applications. The project develops, validates, and releases quality-controlled, long-term CDRs of total column water vapour (TCWV) and water vapour profiles in the stratosphere (2D), as well as a five-year data record of water vapour profiles in the troposphere and lower stratosphere (3D).


The aim of the workshop is to bring together the broader water vapour community, including those interested in the generation of water vapour CDRs and data users (such as climate modellers and NWP researchers) in order to discuss the most recent scientific applications and challenges in processing and using water vapour CDRs.

Topics of the workshop include:

  • Discuss challenges related to the generation of water vapour CDRs.
  • Show-case climate user applications of water vapour CDRs (with focus on WV_cci CDRs).
  • Collect and update user requirements for atmospheric water vapour.
  • Present and discuss results from climate analysis, climate applications, and process studies using water vapour CDRs.


The workshop will be carried out online as a Zoom webinar, consisting of a series of 12' (+2') presentations and discussion blocks. Splinter groups: TCWV, stratosphere and UTLS.

The workshop is scheduled Mon 14 – Wed 16 June 2021 at 14–17 CEST / 13–16 BST / 6–9 MDT. 

A link to the Zoom webinar was sent by e-mail to registered participants.

Presentation material can be downloaded after log in.

  • Alessio Bozzo
  • Alexander Haefele
  • Alexandre M. Ramos
  • Andreas Petzold
  • Angela Benedetti
  • Arantxa Triana Gómez
  • Axel Lauer
  • Axel von Engeln
  • B.J. Sohn
  • Brian Kerridge
  • Charis Benetatos
  • Chia-Wei Lan
  • Chloé Radice
  • Christian Borger
  • Christian Rolf
  • Clarissa Kroll
  • Daan Hubert
  • Dale Hurst
  • Elisa Castelli
  • Enzo Papandrea
  • Eva Borbas
  • Fabrice Chane Ming
  • Farahnaz Khosrawi
  • Gabriele Stiller
  • Gerald Nedoluha
  • Gisèle Krysztofiak
  • Hans Gleisner
  • Hao Ye
  • Helene Brogniez
  • Henri Diemoz
  • Herman Smit
  • Hugues Brenot
  • Irina Petropavlovskikh
  • Janna Rückert
  • Jean-Christopher Lambert
  • Jeffery Langille
  • Jia He
  • Jiangfeng Wei
  • Johannes K. Nielsen
  • Johannes Pletzer
  • John Forsythe
  • John Haynes
  • Jonathon Wright
  • Jorge Eiras Barca
  • Juergen Fischer
  • Kaley Walker
  • Kate Willett
  • Kent Lauritsen
  • Kerstin Ebell
  • Klaus Gierens
  • Klemens Hocke
  • Kostas Eleftheratos
  • laurence picon
  • Leonie Bernet
  • Loredana Spezzi
  • Marc Schroeder
  • Marloes Penning de Vries
  • Matthias Schneider
  • Michaela Hegglin
  • Michel Van Roozendael
  • Mohamadou Diallo
  • Mélanie Ghysels-Dubois
  • Nuria Plaza
  • Olaf Danne
  • patrick sheese
  • Paul Jeffery
  • Philip Watts
  • Ranjitkumar Solanki
  • René Preusker
  • Richard Allan
  • Robert Sica
  • Robin Thor
  • Rodrigo San Martin
  • Roeland Van Malderen
  • Roger Saunders
  • Ruonan Wang
  • Sabine Brinkop
  • Sajad Tabibi
  • Sean Davis
  • Simon Pinnock
  • Stefan Noël
  • Susanna Winkelbauer
  • Susanne Rohs
  • Tao Wang
  • Thomas Chen
  • Thomas Spangehl
  • Thomas Wagner
  • Tim Trent
  • Tobias Küchler
  • Tom Vonder Haar
  • Ulrich Bundke
  • Ulrike Falk
  • Vasura Jayaweera
  • Viju John
  • Viktoria Sofieva
  • William Ingram
  • Yuanbo Liu
    • 2:00 PM 3:30 PM
      WV_cci data sets and validation
      Conveners: Daan Hubert (BIRA-IASB), Pauline Cocevar (Telespazio)
      • 2:00 PM
        Welcome 10m
        Speakers: Michaela Hegglin (University of Reading), Marc Schröder (DWD Offenbach)
      • 2:10 PM
        Introduction to CCI 10m
        Speaker: Simon Pinnock (ESA Climate Office)
      • 2:20 PM
        Introduction to WV_cci 10m
        Speaker: Michaela Hegglin (University of Reading)
      • 2:30 PM
        Total Column Water Vapour (TCWV) from WV_cci: introduction to data records 15m
        Speaker: Marc Schröder (DWD Offenbach)
      • 2:45 PM
        Total Column Water Vapour (TCWV) from WV_cci: validation 15m
        Speaker: Ulrike Falk (DWD)
      • 3:00 PM
        Stratospheric profiles from WV_cci: introduction to data records and validation 15m
        Speaker: Michaela Hegglin (University of Reading)
      • 3:15 PM
        UTLS profiles from WV_cci: introduction to data records and validation 15m
        Speaker: Hao Ye (University of Reading)
    • 3:30 PM 3:45 PM
      Break 15m
    • 3:45 PM 4:30 PM
      User requirements
      Conveners: Michaela Hegglin (University of Reading), Helene Brogniez (LATMOS / UVSQ)
      • 3:45 PM
        Introduction 10m
        Speaker: Michaela Hegglin (University of Reading)
      • 3:55 PM
        Breakout Groups : total column, stratosphere and UTLS 20m
      • 4:15 PM
        Reports breakout results & discussion 15m
    • 2:00 PM 3:15 PM
      Vertically resolved water vapour: In-situ, balloon and satellite observations
      Conveners: Daan Hubert (BIRA-IASB), Richard Siddans (RAL)
      • 2:00 PM
        Water vapor data from the Jülich Airborne In-situ Database (JULIA) 15m

        The JULIA (the Jülich In-Situ Airborne) data base comprises water vapor measurements from more than 50 research aircraft field campaigns spanning over a time period more than 20 years starting in 1997.

        We analyzed the JULIA water vapor data set together with JETPAC Merra2 meteorological data in the frame of the SPARC OCTAVE-UTLS initiative. We show that water vapor variability in the UTLS was best reduced if using a combination of jet-based and tropopause based coordinates. A persistent variability of H2O below Theta=350K remains and can't be reduced by coordinate transformations. Trend estimates therefore remain highly uncertain below 350K, but show indications for slightly negative trend of H2O in the LMS.

        Speaker: Christian Rolf (Forschungszentrum Jülich)
      • 2:15 PM
        IAGOS water vapour and RH_ice products for the global troposphere and extratropical tropopause regions 15m

        The water vapour and Relative Humidity (RH) data set provided by the IAGOS research infrastructure ( since 1994 covers the troposphere and extratropical tropopause regions in the Northern Hemisphere and the upper troposphere of the subtropics to tropics. Besides data provision by open access, an automated tool for data processing and quality control permits near-real-time transmission of IAGOS Capacitive Hygrometer data. We demonstrate the use of the NRT water vapour profiles by CAMS for model validation and present results from a 15-years study on ice supersaturated air masses in the northern latitudes. We aim to use the opportunity of this workshop to identify synergies between CDRs and the IAGOS water vapour products.

        Speaker: Susanne Rohs (Forschungszentrum Jülich)
      • 2:30 PM
        Water vapor measurements in the tropical upper troposphere and lower stratosphere : applications in UT-LS and deep convection. 15m

        STRATEOLE 2 is a French-American project based on long-duration measurements under superpressure balloon to study dynamics and processes in the TTL and the lower stratosphere. Here we present water vapor measurements by the Pico-SDLA diode laser spectrometer during the first campaign (Dec. 2019 - Feb. 2020).
        In this presentation, we analyse the regional in situ tape recorder signal obtained. We discuss the challenges beyond such analysis. The anomaly of the in situ measurements with respect to a satellite-borne mean climatology from Aura MLS v5 allows the identification of singular events responsible for modulation of the local water vapor content : Kelvin wave, packet of gravity waves and possibly deep convection.

        Speaker: Dr Mélanie Ghysels-Dubois (GSMA/CNRS)
      • 2:45 PM
        The Stratospheric Water and Ozone Satellite Homogenized (SWOOSH) database: A long-term database for climate studies 15m

        This presentation describes the Stratospheric Water and Ozone Satellite Homogenized (SWOOSH) database, which includes vertically resolved ozone and water vapor data from a subset of the limb profiling satellite instruments operating since the 1980s. The primary SWOOSH product is a vertically-resolved zonal-mean monthly-mean merged timeseries. This presentation details the choice of reference measurements, homogenization, and gridding process involved in the construction of the combined SWOOSH product. Furthermore, a discussion of uncertainties in the combined SWOOSH record is presented, and recent efforts at improving uncertainty estimates and including the SAGE III/ISS data are described.

        Speaker: Sean Davis (NOAA Chemical Sciences Laboratory)
      • 3:00 PM
        Water vapour isotopologue observations from space and their scientific potential 15m

        Tropospheric water vapour isotopologue ratios (expressed as δD) give unique insight into moisture sources and cloud processes, in particular if analysed together with the water vapour concentration. In this presentation we briefly introduce the theory of {H2O,δD}-pair distributions, present the recently published MUSICA IASI {H2O,δD}-pair data set (1.5 billion individual data points, offering twice daily global coverage for 10/2014 to 12/2020), document their potential for improving global atmospheric analyses, and present concrete examples of moisture studies over the West African monsoon region. We discuss the possibility for generating tropospheric water vapour isotopologue profile data by combining the two sensors IASI and TROPOMI.

        Speaker: Matthias Schneider (Karlsruhe Institute of Technology)
    • 3:15 PM 3:30 PM
      Break 15m
    • 3:30 PM 4:15 PM
      Vertically resolved water vapour: GPS RO & surface observation
      Conveners: Ulrike Falk (DWD), Hao Ye (University of Reading)
      • 3:30 PM
        Retrieval of tropospheric specific humidity profiles with high vertical resolution from Radio Occultations 15m

        Satellite based Radio Occutations (GNSS-RO) are used to produce water vapour climate data records, with high vertical resolution. In the tropopshere the RO measurement, in combination with background model data, can be inverted to a water vapour product. The RO technique is calibration free, thus to some extend free from instability issues, but the inclusion of model background data may cause changes in biases over time.

        In this presentation we will introduce the RO technique and the algorithms used to invert RO signals. We will focus on what is being done in the EUMETSAT ROM SAF to get optimal humidity information from RO measurements, and briefly discuss future plans for improving stability of RO humidity products.

        Speaker: Dr Johannes K. Nielsen (Danish Meteorological Institute)
      • 3:45 PM
        ROM SAF humidity climate data records based on radio occultation 15m

        Many studies have by now demonstrated the accuracy of GNSS Radio Occultation (RO) data, and their usefulness as a stable climate reference. Because of this RO is now firmly established in climate reanalysis, where data are assimilated without bias correction. However, retrieval of water vapor data in the troposphere from RO refractivity requires a priori (background) information, which means that inhomogeneities in the background data may impact humidity Climate Data Records (CDRs).

        Here, we will describe the ROM SAF CDRs and ICDR, with a focus on the temperature and humidity data records. The status and observed homogeneity of the RO time series is discussed, and the ROM SAF plans for development of the humidity CDRs are outlined.

        Speaker: Hans Gleisner (Danish Meteorological Institute)
      • 4:00 PM
        How does the HadISDH in situ surface humidity product compare with other estimates? 15m

        HadISDH is a global gridded surface humidity climate monitoring product based on quality controlled and bias adjusted in situ observations from weather stations and ships. It shows that while the amount of surface water vapour has increased since the 1970s, the air has become less saturated. Similar results are found in the ERA5 reanalysis but there are temporal and spatial differences that are yet to be understood. Satellite estimates of water vapour may help to illucidate some of the reasons for these differences and help to understand changes in water vapour where there are no in situ observations. The respective uncertainties and differences in observing and representing water vapour will need to be taken into account in any comparison.

        Speaker: Kate Willett (Met Office Hadley Centre)
    • 4:15 PM 5:15 PM
      Total column water vapour: Observations & scientific applications
      Conveners: Marc Schröder (DWD Offenbach), Daan Hubert (BIRA-IASB)
      • 4:15 PM
        A systematic assessment of water vapor products in the Arctic: from instantaneous measurements to monthly means 15m

        Water vapor is an important component in the water and energy cycle of the Arctic. With respect to Arctic amplification, changes of water vapor are of high interest but are difficult to observe due to the sparsity of data in that region. The ACLOUD/PASCAL campaign performed in May/June 2017 in the Arctic North Atlantic sector offers the opportunity to investigate the quality of various satellite and reanalysis products: reference IWV measurements at R/V Polarstern and at Ny-Ålesund are used to investigate the quality of instantaneous satellite measurements from AIRS, AMSR2, GOME, IASI and MIRS. In future, we will also exploit the comprehensive measurements of MOSAiC providing a full year of IWV reference measurements in the central Arctic.

        Speaker: Kerstin Ebell (University of Cologne)
      • 4:30 PM
        CCI water vapor user application: Contribution to atmospheric moisture transport. 15m

        Most of the Eulerian and Lagrangian models used in moisture transport analysis rely on reanalysis products for their initial and boundary conditions. Although these phenomena are varied, atmospheric rivers (ARs) and low-level jets (LLJs) are the two most prominent phenomena. We have compared the vertically integrated water vapor column (IWV) fields provided by the two most commonly used reanalyses with the new CCI product. This analysis has been carried out for the regions of interest for moisture transport processes and over 35k AR and 10k LLJ events. Likewise, the goodness of temporal correlations has been evaluated. The results show a high degree of agreement, with relatively small BIAS and high temporal correlations for these regions.

        Speaker: Jorge Eiras Barca (University of Vigo)
      • 4:45 PM
        The use of water vapour products in Atmospheric Rivers Science 15m

        The Mediterranean climate is usually characterized by warm and hot summers intermingled with mild and rainy winters.

        A common feature shared by all Mediterranean regions is the occurrence of Atmospheric Rivers (ARs). ARs are relatively narrow and elongated filaments of high water vapour transport, which are associated with tropical moisture exports and can lead to intense precipitation episodes. ARs detection techniques use the fields of integrated water vapour (IWV) content or integrated water vapour transport (IVT).

        This presentation highlights the need of the use of novel long-term total column water vapour climatologies or/and water vapour profiles in order to better understand the genesis and dynamics of such phenomena.

        Speaker: Alexandre M. Ramos (Instituto Dom Luiz, Faculdade de Ciências da Universidade de Lisboa)
      • 5:00 PM
        Discussion of observational & process-study gaps 15m
    • 2:00 PM 3:15 PM
      Total column water vapour: Observations and climate analysis
      Conveners: René Preusker (Freie Universität Berlin), Tim Trent (Universiy of Leicester)
      • 2:30 PM
        Comparison of Sentinel-5P total water vapour columns from different algorithms 15m

        The Air Mass Corrected Differential Optical Absorption Spectroscopy (AMC-DOAS) approach to derive water vapour vertical columns was originally developed for Global Ozone Monitoring Experiment (GOME) on ERS-2 and also has been applied to measurements from SCIAMACHY and GOME-2. Recently, it has been applied to measurements from TROPOMI onboard Sentimel-5P.

        Currently there is no operational water vapour product from TROPOMI. Nevertheless there are already existing methods to retrieve total water vapour in different spectral regions from TROPOMI. In this presentation, we compare the new AMC-DOAS product with other Sentinel-5P water vapour products from the Netherlands Institute for Space Research and Max Planck Institute for Chemistry.

        Speaker: Mr Tobias Küchler (University of Bremen)
      • 2:45 PM
        Novel assessment of model relative humidity with satellite probabilistic estimates 15m

        Remote sensing data are often used to assess model forecasts on multiple scales, generally by confronting past simulations to estimates. My work consists of developing a novel probabilistic method that evaluates tropical atmospheric relative humidity (RH) profiles simulations by confronting them to probability distributions of finer scale satellite estimates. This probabilistic approach allows to keep the sub-grid variability and avoids the classical determinist simplification that consists of working with a simple “best” estimate. The method is tested on RH profiles simulated by the NWP model ARPEGE for the period April-May-June 2018 and uses as reference probabilistic RH field estimated by SAPHIR (microwave sounder aboard Megha-Tropiques)

        Speaker: Chloé Radice (LATMOS / IPSL)
      • 3:00 PM
        AIRWAVE - TCWV datasets from TIR dual view ATSR-like instruments 15m

        The Advanced Infra-Red WAter Vapour Estimator (AIRWAVE) algorithm was developed to derive the Total Column of Water Vapor for the ATSR-like instruments. AIRWAVE exploits TIR channels radiances over the water surfaces in cloud-free scenarios.
        The first version of the dataset (v1) was part of the G-VAP archive. A second version of the code was produced (v2) where some of the shortcomings of the previous version of the algorithm have been corrected. Validation results against products derived from the SSMI/S mission and the ARSA radiosonde database highlight the quality of both v1 and v2 datasets.
        In the frame of an EUMETSAT project, we are currently extending the AIRWAVE algorithm to the measurements of the SLSTR sensor aboard Sentinel-3.

        Speaker: Elisa Castelli (ISAC-CNR)
    • 3:15 PM 3:30 PM
      Break 15m
    • 3:30 PM 4:55 PM
      Total column water vapour: Model intercomparisons
      Conveners: Hao Ye (University of Reading), Jorge Eiras Barca (University of Vigo)
      • 3:30 PM
        Variability of tropical water vapor from CMIP6 GCMs and ESA CCI+ “Water Vapor” climate data records 15m

        Water vapor is strongly associated with large-scale atmospheric circulation. Here the water vapor variation in the tropical region (30S ~ 30N) is analyzed for 7 global climate models (CMIP6 framework) and the new global water vapor climate data records (CDR) generated within the ESA Water Vapor CCI+ project (WV_cci). The water vapor data are decomposed into large-scale dynamical regimes (intervals of 10 hPa/day) using the 500 hPa atmospheric vertical velocity to evaluate its link to water vapor variation. While the basic picture of the tropical atmosphere is properly represented by the models (moister in ascending branches, drier in subsiding branches) there are noticeable differences in the patterns that will be discussed.

        Speaker: Jia He (LATMOS, Guyancourt, France)
      • 3:45 PM
        Evaluation of water vapour changes in CMIP6 simulations 15m

        Increases in tropospheric water vapour with warming drive a powerful amplifying effect on climate change, alter the surface and atmospheric energy balance and at low altitudes enhance moisture transport into weather systems leading to more intense precipitation. An evaluation of water vapour changes and variability simulated by a selection of CMIP6 climate model “historical” and “amip” experiments at global and tropics-wide scales will be presented using ground-based and satellite estimates from HadISDH, SSMIS and AIRS and the ERA5 reanalysis.

        Speaker: Richard Allan (University of Reading)
      • 4:00 PM
        Evaluating CMIP6 models with ESACCI data and the ESMValTool 15m

        Biases in model simulations of present-day climate do not only affect confidence in the capability of the models to correctly reproduce current climate but also raise concerns about the accurate representation future climate change. In this study we investigate the performance of state-of-the-art global climate models from the sixth phase of the Coupled Model Intercomparison Project (CMIP6) by comparing simulated water vapor and cloud properties with satellite observations. A focus is the variability of water vapor on seasonal and interannual time scales. The analysis is performed with the Earth System Model Evaluation Tool (ESMValTool), a community diagnostic and performance metrics tool for the evaluation of Earth System Models.

        Speaker: Axel Lauer (DLR, Institut für Physik der Atmosphäre)
      • 4:15 PM
        Water vapour validation in a general circulation model: effects of model resolution 15m

        With the recent European project PRIMAVERA and the continuing international HighResMIP comparison, there is now a great deal of data to look at the effect of resolutions on general circulation models. In the Hadley Centre's, while globally-integrated quantities such as climate sensitivity seem largely stable when resolution is changed, the impacts of climate change are of course felt locally, and there seems to be more sensitivity on more local scales. For example, there is evidence for rather higher resolution than normal being needed for the response of precipitation over Western Europe to climate change. I shall show preliminary results from comparing water vapour validation at different resolutions.

        Speaker: William Ingram (Met Office Hadley Centre)
      • 4:30 PM
        Examining Water Vapour Residency Times from Observational and AMIP Ensembles 15m

        Water vapour is a crucial component of the Earth climate system. As the largest natural contributor to the greenhouse effect, it also has the capacity to regulate evaporative and transpiration processes. Therefore, water vapour is closely connected to both the global hydrological cycle and energy budget.

        The time water spends in the atmosphere between evaporation and precipitation is directly linked to moisture transport, extreme precipitation and hydrological sensitivity due to climate change. This study investigates the residence time of water vapour from observational and model ensembles to evaluate our current understanding and assess how the hydrological cycle has responded to increasing temperatures over a 26 year period.

        Speaker: Tim Trent (Universiy of Leicester)
      • 4:45 PM
        Discussion of climate analysis, applications & process studies 10m
    • 4:55 PM 5:00 PM
      Conveners: Michaela Hegglin (University of Reading), Pauline Cocevar (Telespazio)