1. H. Rott –CoReH2O Snow_RS-Workshop_Boulder_Aug-2013 CoReH 2 O – Preparations for a Radar Mission for Snow and Ice Observations H. Rott 1, D. Cline 2, C. Duguay 3, R. Essery 4, P. Etchevers 5, I. Hajnsek 6, M. Kern 7, G. Macelloni 8, E. Malnes 9, J. Pulliainen 10, S. Yueh 11 1 University of Innsbruck & ENVEO IT, Austria 2 NOAA, NWS, Hydrology Laboratory, USA 3 University of Waterloo, Canada 4 University of Edinburgh, UK 5 Meteo-France, Saint Martin d’Héres, France 6 DLR-HR, Germany & ETH Zürich, Switzerland 7 ESA-ESTEC, Noordwijk, NL 8 IFAC-CNR, Firenze, Italy 9 NORUT IT, Tromsǿ, Norway 10 Finish Meteorological Institute, Helsinki, Finland 11 JPL-Caltech, Pasadena, USA

2. H. Rott –CoReH2O Snow_RS-Workshop_Boulder_Aug-2013 Background Information CoReH 2 O  Cold Regions Hydrology –High Resolution Observatory Submitted to ESA in response to the 2005 Call for Earth Explorer Core Missions (EE-7) Selected as one of 6 missions for Pre-Phase A studies In 2009 selected as one of 3 missions for detailed scientific and technical studies, Phase A Scientific studies included retrieval algorithm development, SAR image simulator, performance analysis, field campaigns, synergy with other satellites, etc. 2 parallel contracts on sensor & satellite development March 2013: Down-selection to one EE7 mission > Biomass

3. H. Rott –CoReH2O Snow_RS-Workshop_Boulder_Aug-2013 Scientific Observation Requirements Primary parameters Spatial scale Regional/Global Sampling (days) Accuracy (rms) Snow water equivalent200 m / 500 m3-15 3 cm for SWE  30 cm, 10% for SWE > 30 cm Snow extent100 m / 500 m3-155% of area Glacier snow accumulation 200 m / 500 m1510% of winter maximum Secondary parameters Diagenetic facies types, glacial lakes Glaciers Ice area; freeze up and melt onset Lake and river ice Melting snow area, snow depth Snow Snow on ice (SWE, melt onset and area); type and thickness of thin ice Sea ice

4. H. Rott –CoReH2O Snow_RS-Workshop_Boulder_Aug-2013 Signal as Basis for SWE Retrieval SnowScat  ° (dB) at Ku-band (16.7 GHz) and X- band (10.2 GHz),  = 40° winter 2010/11, vs. SWE in snow pits, Sodankylä, Finland (NoSREx-2).

5. H. Rott –CoReH2O Snow_RS-Workshop_Boulder_Aug-2013 CoReH 2 O SAR Sensor Requirements ParameterKu-band SARX-band SAR Frequency17.2 GHz9.6 GHz PolarizationVV, VH Swath width, Inc angle ≥ 100 km; 30° to 45° range Spatial resolution≤ 50 m x 50 m (≥ 4 ENL) NESZ≤ -25dB VH≤ -27dB VH Radiom. Stability / Bias≤ 0.5 dB / ≤ 1.0 dB 2 Mission concepts ScanSAR EADS-Astrium Thales-Alenia

6. H. Rott –CoReH2O Snow_RS-Workshop_Boulder_Aug-2013 Cost Function Iterative SWE Retrieval – Constrained Minimization  (.) backscatter forward model (radiative transfer, RT) X2 free model parameters (SWE, eff. grain radius R E ) ii th CoReH 2 O Band (for i=1,..4: X vv, vh; Ku vv, vh) jindex for free model parameters: SWE var i variance of measured  ° backscatter value in CoReH 2 O band i c 1,..,c r RT model configuration parameters (T s,  s,  as ) Regularization Regularization parameters are needed to constrain the inversion: a-priori R E, SWE Forward model used for iteration: Forward model - Measurement

7. H. Rott –CoReH2O Snow_RS-Workshop_Boulder_Aug-2013 Performance Analysis SWE Retrieval – Simulated Data SWE in open forest 20% fractional cover Based on backscatter simulations with Synthetic Scene Generator (SSG) Unbiased regularization RMSD between retrieved and true SWE Red grid: observ requirement Snow on open land Retrievals with improved algorithm 50 m grid size; speckle filter 7 x 7

8. H. Rott –CoReH2O Snow_RS-Workshop_Boulder_Aug-2013 Performance Analysis SWE Retrieval – Simulated Data 15% bias for regularization parameter R E (effective grain radius) Impact of bias in regularization parameters  Snow on open land. 50% bias for regularization parameter SWE

9. H. Rott –CoReH2O Snow_RS-Workshop_Boulder_Aug-2013 Field Experiments with Airborne Sensor SnowSAR Field campaigns Sodankylä March 2011, winter 2011/12 AlpSAR 2013 – Austrian Alps SnowSAR Characteristics Frequencies 9.6 GHz, 17.25 GHz Polarization Polarimetric Modulation FMCW Bandwidth 150 MHz Look angle  35° to 45° AlpSAR Leutasch 23-02-2013

10. H. Rott –CoReH2O Snow_RS-Workshop_Boulder_Aug-2013 SWE Map from Airborne Backscatter Data SWE map, derived from SnowSAR data, Sodankylä, 15/03/2011 Performance: SWE obs – SWE ret = -5 mm Stand. error : 11 mm A-priori estimates for retrieval input by CoSDAS snow model driven by HIRLAM forecast data