How to Review the Performance/Adequacy of ECV Observations? - Science Perspective from an ECV Producer -

Transcription

1 How to Revew the Performance/Adequacy of ECV Observatons? - Scence Perspectve from an ECV Producer - Wolfgang Wagner wolfgang.wagner@geo.tuwen.ac.at Department of Geodesy and Geonformaton (GEO Venna Unversty of Technology (TU Wen

2 Sol Mosture: From Scence to Operatons Hydrology SAF Cooperaton wth EUMETSAT AMG and ECMWF to delver 25 km ASCAT surface sol mosture data n near-real-tme Dsaggregated 1 km ASCAT/ASAR sol mosture maps Assmlated ASCAT sol mosture profle Coperncus Global Land Cooperaton wth AMG and VITO to delver CCI C3S Daly 25 km Sol Water Index (SWI product based on H-SAF sol mosture data Evoluton actvty to produce 1km ASCAT/Sentnel-1 SWI data Cooperaton wth Vandersat EODC and others to delver Long-term (1978 up to present 0.25 merged actve/passve mcrowave sol mosture product Internatonal Sol Mosture Network Global data hostng faclty for n stu sol mosture data

3 NRT 25 km ASCAT SM Servce Evoluton Was ntated as Day 2 product outsde H-SAF on recommendaton by Met Offce and ECMWF to mplement t more quckly startng operatons n 2008 Was brought nto H-SAF n 2012 (start of CDOP2 Roles EUMETSAT NRT operatons TU Wen R&D Delvery of model parameters for NRT processor AMG NRT testng chan

4 1 km Sentnel-1 SM Data SSM1km on wth ISMN statons used for valdaton

5 Sol Mosture Clmate Data Record ESA Clmate Change Intatve (CCI 3137 regstered users (status Latest release: v03.2 on datasets: Merged actve merged passve and combned actve-passve Transfer to Coperncus Clmate Change Servce (C3S Prepared for BAMS State of the Clmate 2016

6 Msson Goal of SMOS and SMAP Launch 2009 Launch 2015 The msson goal of SMOS and SMAP s to provde absolute sol mosture retrevals wth an accuracy of 0.04 m 3 m -3. Targeted nformaton: absolute sol mosture Accuracy metrc: root mean square error (RMSE n m 3 m -3

7 Problems of usng RMSE as Valdaton Metrc Dfferent applcatons have dfferent requrements There s also not somethng lke one clmate requrement Sol mosture exhbts hgh varablty at small and large scales In stu sensors can be accurate at pont scale (when properly calbrated but show n a general a bas when used for representng larger areas Mean (red and staton (black n-stu sol mosture tme seres. REMEDHUS network n Span. Unversty of Salamanca

8 Sgnal versus Nose The nformaton content of sol mosture s n our vew better charactersed by the sgnal-to-nose rato (SNR Key crteron n data assmlaton Sgnal s ted to a certan scale Nose refers to random nstrument nose as well as representatveness errors SNR s scale dependent Sol mosture scalng approaches Hghly non-lnear hydrologcal processes are assumed to lnearze at coarse satellte scales Standard error model α + ( +...Satellte retreval or model sol mosture..."true"sol mosture state α... lnear parameters... resdual error

9 Trple Collocaton Orgnally proposed to estmate random error varances Covarance-formulaton ( ( ( α α α j Assumptons: 1 Error varances: Scalng coeffcents: j j } { j j Stoffelen A. (1998. Toward the true near surface wnd speed: Error modelng and calbraton usng trple collocaton. Journal of Geophyscal Research: Oceans ( (C

10 Sgnal to Nose Rato More easy nterpretablty when expressed n decbel unts SNR [db] 10log 0 db: sgnal varance nose varance +/- 3 db: sgnal varance double / half nose varance Gruber A. C. H. Su S. weback W. Crow W. Dorgo W. Wagner (2016 Recent advances n (sol mosture trple collocaton analyss Internatonal Journal of Appled Earth Observaton and Geonformaton

11 Evoluton of ASCAT Valdaton Metrcs Untl 2012: RMSE as for SMOS and SMAP : Correlaton to external model data set From 2016: SNR appled to commtted areas only Crtera snce 2016 Crtera Mask Commtted

12 Some Thoughts on the Montorng of ECVs Our current approach to montorng of the adequacy ECVs currently reles on expert judgements Expert judgement s much more encompassng than one benchmark et are there more objectve and quanttatve ways? Overall scentfc usefulness Uptake by the user communty Nowadays the mpact of publcatons s well documented. What about data and the software used for producng t? How may one beneft from and nteract wth emergng ntatves/ organsaton/technologes? DataCte ( Depsy for software ctatons ( Usng GtHub ( to store publsh and collaborate on open machne-readable datasets Etc.