GlobVapour Newsletter Volume 4, Issue 1 / 2012

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1 GlobVapour Newsletter Volume 4, Issue 1 / 2012 DEFINITION: WATER VAPOUR Water in the form of a gas, produced by evaporation. Afrikaans: wasem, stoom Chinese: 水蒸气 Danish: vanddamp Finnish: vesihöyry French: vapeur d'eau German: der Wasserdampf Italian: vapore acqueo gasformi Russian: водяные пары Spanish: vapor de agua Turkish: su buharı GlobVapour final dataset released and validated and freely available on IASI-Assessment results Executive project summary

Page 2 of 8 European Space Agency (ESA) DUE GlobVapour (2009-2012) Development of Global Water Vapour Monitoring Services Dear reader, the GlobVapour project has been officially finalised on the 31

The challenges of the last months have been completed and the project successfully passed its review on the final project meeting, which was held at ESA-ESRIN in Frascati/Italy mid of January.

2 Page 2 of 8 European Space Agency (ESA) DUE GlobVapour ( ) Development of Global Water Vapour Monitoring Services Dear reader, the GlobVapour project has been officially finalised on the 31 March The challenges of the last months have been completed and the project successfully passed its review on the final project meeting, which was held at ESA-ESRIN in Frascati/Italy mid of January. But first, let us have a view backwards: Already in September 2011, the ESA DUE GlobVapour project carried out its second User Consultation Meeting in Oslo, Norway. The meeting offered a great opportunity for intense discussions as it brings together the producers and users of water vapour data sets. We are proud to say, that the final multi-annual global water vapour data sets have been processed for final products, and are freely available on the projects web page Ready in time, the standalone processor was completed: all processors (GOME/SCIA/GOME-2 L2 and L3, SSM/I L2, MERIS L2, and SSM/I+MERIS L3) have been successfully implemented. The data have been validated for the final period (see article on page 4 and 5) and both final products have been inter-compared with each other (read page 6). Concerning documents, like the Product User Guide (PUG), Algorithm Theoretical Baseline Document (ATBD) or the Product Validation Report (PVR), have been updated for the final products and can be found on the projects web page. Representatives of the project consortium and user group at the Final Project Meeting at ESA-ESRIN in Frascati/Italy. Another interesting topic was the IASI Assessment. Various results have been carried out. Some Lessons learned have been summarised in the article on page 3. Even though the project end has been reached, and the partners continue to work on GlobVapour related topics. These will be: Summarise lessons learned from IASI assessment for publication in GEWEX NEWS. Finalise publication on SSM/I+MERIS. Participate with GlobVapour products in the GEWEX water vapour and temperature profile assessment. We highly appreciate the valuable feedback from users, the user group and the wider community. The software provision from the ESA STSE WACMOS project and from the NWP SAF is acknowledged. Dr. Marc Schröder (DWD) -Project ManagerDr. Bojan R. Bojkov (ESA) -Technical Officer-

3 Page 3 of 8 IASI Assessment Martin Stengel Deutscher Wetterdienst (Offenbach / Germany) In the framework of the DUE GlobVapour Project a significant part was devoted to conduct an assessment of IASI water vapour retrievals, inter-comparing their properties, characteristics and performances with respect to reference observations of water vapour. The IASI retrieval results of 5 different schemes (EUMETSAT, DWD, UKMO, NOAA, DLR) were evaluated and validated. As reference for the validations ground-based observations of atmospheric water vapour taken at ARM (ground-based MWR and radiosonde) and GUAN (radiosondes) were selected. Datasets had been composed containing the TCWV inferred from radiosonde profiles and the nearest neighbour IASI retrievals. Various collocation criteria were applied and tested. For temporal collocation for example criteria of 3 hours had been chosen to still ensure similar weather conditions and, at the same time, still ensure a large enough data sample. The validation datasets had been analysed, major statistical parameters calculated and reported and the results visualized. Detailed information can be found in the IASI Assessment report (Stengel et al., 2012). This initiative provided firstly very valuable information about each IASI scheme and its performance, and secondly a guidance for future assessments, as for example planned in the GEWEX framework. Bias and standard deviation (STD) of each retrieval with respect to the mean radiosonde profile. Eight retrievals have been compared. Lessons learned Selected recommendations for future assessments: Reference measurements (e.g. flight campaigns, etc. ) should be included to have independent results from assimilated data of NWP/reanalyses, which are often used as background information. A common set of background and auxiliary/ancillary data of radiances is suggested. A prescribed common cloud mask would be helpful to lead to a unified validation data set. Clear definition of the criteria the final conclusion should be based on. Recommendation to utilise software following the approach of Pougatchev (2008) and Pougatchev et al. (2009) instead of standard validation software. Advantages are: the model account differences in horizontal, vertical, and temporal resolution as well as noise level of the IASI instrument and radiosondes it further allows an assessment of the error information deduced from validation Excellent teamwork and common willingness of all developers and providers is required to come to a high end solution. Pougatchev, N., 2008: Validation of atmospheric sounders by correlative measurements. Appl. Opt., 47, Pougatchev, N. et al., 2009: IASI temperature and water vapour retrievals error assessment and validation. Atmos. CHem. Phys. Discuss., 9, Stengel, M. et al., 2012: ESA GlobVapour IASI assessment final report.

4 Page 4 of 8 GlobVapour final product: Combined SSM/I+MERIS product Combined SSM/I+MERIS TCWV products have been validated for the final period , using satellite-based (AIRS and ATOVS) and ground-based measurements (radiosonde and microwave radiometer). Comparing SSM/I+MERIS with over land and coastal regions shows a small wet bias over coast. AIRS show a wet bias for all scenes, being smallest over land for AIRS, by reason of the applied AIRS cloud-mask. For ATOVS SSMI+MERIS shows a dry bias, which is smallest over ocean. Versus the most validation data sets, SSM/I+MERIS is drier. Validation method and detailed results can be found in the Product Validation Report. Overall mean for SSM/I + MERIS vs. ARM and versus other validation data for SSM/I + MERIS for Sensors Valid grids (%) Bias (kg/m2) RMSE (kg/m2) AIRS (Aqua) 29.7 ± 2.3 +(0.52 ± 0.18) 2.26 ± 0.11 ATOVS 73.7 ± 2.8 -(1.05 ± 0.29) 3.30 ± 0.20 Raob GUAN 48.8 ± 7.0 -(0.94 ± 0.72) 4.03 ± (1.97 ± 2.48) (3.05 ± 2.50) 3.93 Technical specifications: Raob ARM 46 total columnar water vapour (TCWV), given in units of kg/m². MWR ARM 46 vertically integrated in a column from surface to 200 hpa Daily composites and monthly means daylight only product spatial resolution of 0.5 over ice-free ocean (SSM/I) and 0.05 over cloud free land and coastal ocean (MERIS) available through web page in low resolution (0.5 )² (high resolution (0.05 )² is available on request) L3 data stored in NetCDF files that are fully compliant with the NetCDF Climate Forecast convention SSM/I observations are oversampled by MERIS observations Ocean area with sun glint, where SSM/I observations are not available, is blended with gridded MERIS data. SSM/I and MERIS data streams are processed independently and combined afterwards to fit comprise composites and monthly means Combined SSM/I + MERIS versus AIRS monthly mean TCWV bias (top) and RMSE (bottom) for

5 Page 5 of 8 GlobVapour final product: GOME/SCIA/GOME-2 product The homogenised GlobVapour total columnar water vapour (TCWV) GOME/SCIA/GOME-2 products have been validated for the final period , using satellite-based (AIRS and ATOVS) and ground-based measurements (radiosonde Sensors and microwave radiometer). The whole period has been only validated against GUAN, the other validation data cover only the period of The GOME products against GUAN radiosondes show a Valid grids (%) Bias (kg/m2) RMSE (kg/m2) 60.9 ± (1.60 ± 0.69) 4.93 ± 1.09 ATOVS 76.5 ± 5.3 -(0.46 ± 3.13) 5.11 ± 0.73 Raob GUAN 71.7 ± (0.72 ± 0.68) 4.66 ± 0.55 Raob ARM 37 -(0.25 ± 2.48) 3.76 MWR ARM 37 -(0.42 ± 3.27) 4.17 AIRS (Aqua) slight dry bias for all scenes, being lowest over sea and highest over land. A similar picture is found against ATOVS. Versus AIRS, a wet bias is evident over all scenes. Validation method and detailed results can be found in the PVR. GOME/SCIA/GOME-2 product versus other validation for final period. GOME/SCIA/GOME-2 versus GUAN radiosondes monthly mean TCWV bias (top) and RMSE (bottom) for Overall mean for GOME like vs. ARM Technical specifications: total columnar water vapour (TCWV), given in units of kg/m². vertically integrated in a column from surface to 200 hpa Weekly and monthly means daylight only product available through web page in spatial resolution of 0.5 over ocean and land L3 data stored in NetCDF files that are fully compliant with the NetCDF Climate Forecast convention homogenised data set: the sensors GOME-1 covers , SCIAMACHY and GOME and 2008

Page 6 of 8 GlobVapour final product cross-comparison: GOME/SCIA/GOME-2 vs. SSM/I+MERIS The GlobVapour final data sets have been compared against each other.

A generic distance of 150 km to the nearest land mass has been used for identification of the coastal area.

6 Page 6 of 8 GlobVapour final product cross-comparison: GOME/SCIA/GOME-2 vs. SSM/I+MERIS The GlobVapour final data sets have been compared against each other. The global distribution of the monthly mean for one exemplary months August 2008 (GOME-2) is shown as well as results for the whole final phase ( ). A generic distance of 150 km to the nearest land mass has been used for identification of the coastal area. A threshold of 10 observations per grid box has been applied for GOME-2 and SSMI+MERIS and 1 for SCIAMACHY(values below this threshold have not been considered). For the difference calculation, the downsampled GlobVapour SSM/I + MERIS combined product has been pixel-wise subtracted from the SCIA/GOME GlobVapour product. All products have been normalised to the latitude dependent area of each grid box. The values are given for the collocated subset of valid grids. On regional basis large differences with positive and negative sign can be observed. In general, it seems that over ocean GOME/SCIA/GOME2 is larger than SSM/I while the difference over land is close to zero. On average for the period , the mean bias is +(0.62 ± 0.59) kg/m2, together with a mean RMSE of (4.41 ± 0.73) kg/m2. In general the observed bias and RMSE values confirm results from the individual validation reports. The most evident feature in the comparison results is a jump in bias and RMSE between December 2006 and January 2007, that is, at the change from SCIA to GOME2. A likely reason for this result is the difference in cloud presence handling. Monthly mean TCWV GOME-2 vs. SSMI+MERIS for 08/2008. BIAS TCWV from GOME2 vs. SSMI+MERIS for Monthly BIAS with err of GOME-2 vs. SSMI+MERIS for RMSE from GOME2 vs. SSMI+MERIS for

Page 7 of 8 Executive Project Summary Marc Schröder Deutscher Wetterdienst (Offenbach / Germany) The European Space Agency (ESA) Data User Element (DUE) is an element of the Earth Observation

7 Page 7 of 8 Executive Project Summary Marc Schröder Deutscher Wetterdienst (Offenbach / Germany) The European Space Agency (ESA) Data User Element (DUE) is an element of the Earth Observation Envelope Programme (EOEP), an optional programme of ESA. The ESA DUE GlobVapour project s main objective was to provide long-term coherent water vapour data sets allowing for improved accuracies and enhanced temporal and spatial sampling. The project successfully produced the total column water vapour data set based on SSM/I and MERIS as well as GOME, SCIAMACHY and GOME2 observations. To ease utilisation the number of valid observations, the standard deviation, the retrieval uncertainty and useful masks such as land/sea/ice masks are included in the netcdf files. An essential aspect of the GlobVapour project was a direct involvement of the user community in the project. The formation of the GlobVapour user group began already prior to the project start. The user group strongly supported the definition of the requirements baseline and guided retrieval and processing development as well as product definition and validation. Furthermore, the project conducted three User Consultation Meetings in the course of the project in order to foster discussions between retrieval, climate and modelling scientists. In total 22 users registered as users of GlobVapour products. This is a remarkable success as the project run only for two years and the final products with reasonable temporal coverage were provided close to project end. The project also compared GlobVapour products to output from sixteen models submitted to the Coupled Model Intercomparison Project (CMIP) 5. A general comment from the user community was that the SSM/I+MERIS dataset is a unique product with unprecedented quality and coverage and was considered valuable during first application studies. The user interest focused on the SSM/I+MERIS product. The retrieval schemes for the final GlobVapour products have been adapted to carry out their implementation into a single and stand alone processing system to foster operational application. At the end of the project the acceptance review test for the processing system was successfully passed. Another essential part of the project was the intensive validation of the GlobVapour products. Various sources have been used as reference for the validation: groundbased, in-situ and other satellite observations which comprise the Diagnostic Data Set, the basis for the validation. The validation results have been documented and together with algorithm theoretical basis documents and product user guides fully describe the GlobVapour products. GlobVapour was in close contact to international activities. It supported the GEWEX Data Assessment Panel in its effort to initiate a water vapour and temperature profile assessment in a joint meeting hosted by ESA-ESRIN. The project conducted a IASI assessment and the experiences from GlobVapour validation activities can be beneficial for the GEWEX assessment. GlobVapour submitted an extended abstract on the combined SSM/I+MERIS product to one of the lead authors of IPCC AR5 in order to potentially get referenced in the AR5. Finally, GlobVapour processors and products will most likely be transferred to sustained and operational environments at ESA and CM SAF. Examples are the MERIS 1D-Var retrieval for implementation into the MERIS reprocessing at ESA and the continuation of the SSM/I+MERIS products by CM SAF.

8 Page 8 of 8 The Project Timeline 01 Dec 2009 Nov 2010 Mar 2011 Jun 2011 Sep 2011 Start of project Release of prototype products (07,08/2007 and 01,08/2008) User Consultation Meeting I together with GEWEX Radiation Panel Meeting in Frascati Release of test products ( ) User Consultation Meeting II during EUMETSAT Meteorological Satellite Conference in Oslo The project passed successfully its final review. The GlobVapour final products are available through the projects web page: GlobVapour News published by the GlobVapour project office at Deutscher Wetterdienst (DWD) Contact Project Manager: Dr. Marc Schröder (DWD) marc.schroeder@dwd.de Technical Officer: Dr. Bojan R. Bojkov (ESA) bojan.bojkov@esa.int User Help Desk Data Request & Technical Support: Dr. Marc Schröder (DWD) marc.schroeder@dwd.de Layout Nadine Schneider Iris Sommerfeld Photography Nadine Schneider (cover) Editorial Date March 2012, updated August 2012 Copyright on images is regarded by team members. Jan 2012 Feb Mar 2012 Final Meeting and User Consultation Meeting III at ESA-ESRIN in Frascati Release of final products ( ) End of project The Project Consortium Deutscher Wetterdienst (DWD) Project lead, product development for SSM/I, MWR, SSM/I + MERIS, IASI + SEVIRI, processing, validation, and dissemination including Help Desk. Freie Universität Berlin (FUB) Product development for MERIS and AATSR, SSM/I + MERIS, processing and validation. Deutsches Zentrum für Luft- und Raumfahrt (DLR) Product development for GOME/SCIAMACHY/ GOME-2, validation and processing. UK Meteorological Office (UKMO) Usage of products in climate model evaluation, comparison of model-to-instrument vs. instrument-to-model approach in climate model evaluation. Brockmann Consult (BC) Development of processing environment and integration of scientific processors. Danish Meteorological Institute (DMI) Provision of validation from radio occultation satellites. Max-Planck-Institut für Chemie (MPI-C) Product development for GOME/SCIAMACHY/GOME-2. National Oceanic and Atmospheric Administration (NOAA) NOAA participates in the IASI retrieval assessment.

EUMETSAT SAF NETWORK. Lothar Schüller, EUMETSAT SAF Network Manager

EUMETSAT SAF NETWORK. Lothar Schüller, EUMETSAT SAF Network Manager 1 EUMETSAT SAF NETWORK Lothar Schüller, EUMETSAT SAF Network Manager EUMETSAT ground segment overview METEOSAT JASON-2 INITIAL JOINT POLAR SYSTEM METOP NOAA SATELLITES CONTROL AND DATA ACQUISITION FLIGHT