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STREMP/DFG Project Results : Estimation of water mass changes Model improvement and coupling

Water mass variation in small basins: assessment of contributions from observations and models - a regional hydrology model WaterGAP3 L. Fenoglio-Marc 1 , R. Rietbroek 2 , S. Grayek 3 , T. aus der Beek 5 , M. Becker 1 , J. Kusche 2 , E. Stanev 4 , , L. Menzel 6

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STREMP/DFG Project Results : Estimation of water mass changes Model improvement and coupling

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  1. Water mass variation in small basins: assessment of contributions from observations and models - a regional hydrology model WaterGAP3 L. Fenoglio-Marc1 , R. Rietbroek2, S. Grayek3, T. aus der Beek 5, M. Becker1 , J. Kusche2 , E. Stanev4 ,, L. Menzel6 1Institute of Physical Geodesy, Technische Universität Darmstadt 2 Institute for Geodesy and Geo-information, Universität Bonn 3 Institut für Chemie und Biologie des Meeres, Universität Oldenburg 4 Institut für Coastal Research (GKSS), Geesthacht 5 Centre for Environmental Systems Research Kassel, Universität Kassel 6 Geographisches Institut, Universität Heidelberg Intergeo, Geodätische Woche, 4-7 October 2010

  2. OUTLINE • STREMP/DFG Project • Results : Estimation of water mass changes • Model improvement and coupling • Results: Assessement of contributions • Conclusions Intergeo, Geodätische Woche, 4-7 October 2010

  3. The Project OUTLINE STREMP: Spatial and temporal resolution limits for regional mass transport and mass distribution Phase 1-2 Estimation and comparison at basin scale Phase 2-3 Coupling of river basin hydrology and oceanography Intergeo, Geodätische Woche, 4-7 October 2010

  4. The Project Semi-closed basins: MED (2.5 106 km2) BLACK SEA(0.5 106 km2) Aim: in interval 2003-2010 a) basin average and 2-D comparison of mass from GRACE (FROM standard GFZ and other solutions) and from steric-corrected altimetry b) separation of mass and steric signal c) closure of water mass budget as basin average and 2-D d) assimilation of GRACE in ocean and hydrological models (coupling of river basin hydrology and oceanography) Intergeo, Geodätische Woche, 4-7 October 2010

  5. The Project Understanding the satellite signal DAROTA ocean tide model EOT10 JIGOG GRACE weekly solutions geocenter motion surface loading TOPO-EUROPE RATSEL-GRACE GRACE regional solution WP 100 - TUD Multi-mission ALTIMETRY retracked altimetry coast and land steric-corrected altimetry mean sea level GOCE to compute MDT WP 200 - TUD + IGG GRACE post-processed solutions GOCE geoid solution WP 500 MDT from NEMO Mass variation/straits flow GRACE for WaterGAP3 calibration Steady-state & long-term processes Steric from T, S from model Short-term processes Altimetry, MDT for assimilation WP300 - ICBM NEMO assimilated OCEAN model BS River runoff for assimilation WP 400 - CESR WaterGAP3 assimilated HYDROLOGY model with GRACE, altimetry, SMOS 6 hourly ocean bottom pressure GRACE solution, mean de-aliasing fields Daily total water storage TASMAGOG IMPLY GRACE solution improved by regional de-aliasing model REGHYDRO GRACE solution improved by regional de-aliasing model WATERGAP Intergeo, Geodätische Woche, 4-7 October 2010

  6. RESULTS seawater mass : GRACE .NE. a-s Land Hydrology a – s = G – h (both terms filtered) • Optimal Filtering, optimal radius • Scaling factors (Attenuation of the signal/rescaling parameter, different way to compute) • 3. Atmospheric correction MOG2D (consistency between altimetry and GRACE pre-processing) 4. Leakage of the hydrology signal on water mass estimation : HYDROLOGY models 5. No-mass change on total altimetry : OCEANOGRAPHY models Intergeo, Geodätische Woche, 4-7 October 2010

  7. RESULTS Leakage of the hydrology signal on water mass estimation : HYDROLOGY models 4. Leakage of the hydrology signal on water mass estimation : HYDROLOGY models Intergeo, Geodätische Woche, 4-7 October 2010

  8. RESULTS • Scaling factors (Attenuation of the signal/rescaling parameter) • different way to compute Intergeo, Geodätische Woche, 4-7 October 2010

  9. RESULTS Recipes GRACE GFZ: GRACE GSM d/o 2-100 GRACE GAD d/o 2-100 GRACE-GPS-OBP loading inversion (Rietbroek 2009) 1 GIA contribution to ewh re-scale (1.39 Med, Altimetry GIA rate correction for geoid corrected Atmospheric effect by DAC (IBC + MOG2D-G) GRACE GRGS: GRACE GSM d/o 2-100 GRACE-GPS-OBP loading inversion (Rietbroek 2009) 1 GIA contribution to ewh re-scale Intergeo, Geodätische Woche, 4-7 October 2010

  10. RESULTS Filter used: anisotropic D12 Re-scaling factor applied : 1.54 MFSTEP version 6 TREND in steric sea level from GRACE: –5.3 +/- 1.1 mm/yr MFSTEP -9.5 +/- 0.6 ECCO -3.1 +/- 0.4 Steric from GRACE: Ampl. = 76 mm, phase = 242 deg MFSTEP: Ampl. = 59 mm, phase = 257 deg Corr: 0.80 , Rms : 23 mm Ampl : 22 +/- 3 mm, ph: 319 deg (a-s) Ampl: 23 +/- 5 mm, ph: 359 deg (Grace) Trend: 9.7 +/- 1.6 mm/yr (MFSTEP) 3.6 +/- 1.6 mm/yr (ECCO) Trend: 6.3 +/- 1.9 mm/yr (Grace, Stocchi) 3.4 +/- 1.9 mm/yr (Grace, Paulson) Corr: 0.84 Rms : 15 mm / 0.5 if DAC/MOG2D is NOT applied to altimetry Low RMS, phase difference of 30 days Intergeo, Geodätische Woche, 4-7 October 2010

  11. RESULTS Filter used: anisotropic D12 Re-scaling factor applied : 1.92 Corr: 0.62 / 0.62 if DAC/MOG2D applied to altimetry Rms : 70 mm RMS differences between re-scaled a-s and G-h are higher than in Mediterranean Sea Intergeo, Geodätische Woche, 4-7 October 2010

  12. MODEL IMPROVEMENT • Hydrology : regional hydrology and water use model WaterGAP3 (UNI Kassel) Figure 1: Mean TWS (Total Water Storage) of the Black and Mediterranean Sea river basins as simulated with WaterGAP3 and mean irrigation water withdrawals as simulated with WaterGAP3. Intergeo, Geodätische Woche, 4-7 October 2010

  13. MODEL IMPROVEMENT • Hydrology : regional hydrology and water use model WaterGAP3 (UNI Kassel) Characteristics: • river basins draining into Mediterranean & Black Sea (missing lower Nile basin and inflow) • Monthly water use • 5’ spatial raster resolution (~ 6 x 9 km per grid cell) • Modelling period: 1901 – 2009 (daily time steps, monthly outputs) • calibration/validation of river run-off against measured runoff data from Global Runoff Data Center (GRDC) • Climate input from CRU, ECMWF and GPCC • 9 compartments (groundwater, soil water, rivers, • canopy layers, snow layers, lakes and wetlands) Output: • Monthly Total Water Storage (TWS) to compare with GRACE derived mass change. • Geo-referenced runoff for all rivers draining into Med and Black Sea as a driver for oceanography modelling Comparison a-s , G-h Input to ocean model Intergeo, Geodätische Woche, 4-7 October 2010

  14. MODEL VALIDATION • Validation of Model WATERGAP3 (STEP 1) • At CERS • Compare WaterGAP3 with its global counterpart WaterGAP2 and GLDAS : • yields higher goodness of fit for WaterGAP3 due to the high number of small • river basins and further developed model structures • Mean annual modelled inflow into both oceans fits well to reported values: • Black Sea: modelled 406 km³ vs. reported 403 km³ per year • Mediterranean Sea: 318 km³ vs. reported 312 km³ per year Intergeo, Geodätische Woche, 4-7 October 2010

  15. MODEL VALIDATION • Validation of Model WATERGAP3 (at CERS) Model comparison (WaterGAP3 with global WaterGAP2 and GLDAS) based on River run-off River runoff is assumed to integrate dynamics an filling levels of all storage compartments (if R correct, also TWS is correct) Figure 3: Modelled cumulated monthly inflow into the Mediterranean Sea and Black Sea. Intergeo, Geodätische Woche, 4-7 October 2010

  16. MODEL VALIDATION • Validation of Model WATERGAP3 (at CERS) Comparison to run-off data Figure 5: Comparison of modelled river runoff from two different hydrological models and a land surface model (GLDAS) with observed river runoff at the GRDC Station “Ceatal Izmail” (ID 6742900) of the Danube River. Intergeo, Geodätische Woche, 4-7 October 2010

  17. MODEL VALIDATION Validation of Model WATERGAP3 (at CERS) In terms of cumulated inflow to both oceans WG3 is more close to reported values than WG2 Mean goodness of WG2 and WG3 compared to observed station data Intergeo, Geodätische Woche, 4-7 October 2010

  18. MODEL ASSESSMENT Russian rivers not included in WaterGap3 (1.9% Share in Jaoshvili (2002))‏ Bulgarian rivers not included in WaterGAP3 (0.52% Share in Jaoshvili (2002))‏ Study of Model Sensitivity to Changed Discharge Shares • Total runoff comes from semi-climatological reconstruction (Grayek et al 2010)‏ • for the 'Clim.-Run' we use discharge shares from Jaoshvili (2002)‏ • for the 'WGAP-Run' we use discharge shares from WaterGAP3 model Grayek S, Stanev E.V., Kandilarov R (2010) On the response of Black Sea level to external forcing: altimeter data and numerical modelling; Ocean Dynamics; 60:123–140 Jaoshvili S (2002) The rivers of the Black Sea. European Environment Agency, Copenhagen (in Russian and English)‏ Intergeo, Geodätische Woche, 4-7 October 2010

  19. MODEL ASSESSMENT Sensitivity of Vertical Characteristics Winter Mixed Layer Depth Intergeo, Geodätische Woche, 4-7 October 2010

  20. MODEL ASSESSMENT Sensitivity of Horizontal Characteristics EOF-Analysis of Steric Heights EOF-3 from Altimetry EOF-3 Equivalent from WGAP-Run EOF-3 Equivalent from Clim.-Run Intergeo, Geodätische Woche, 4-7 October 2010

  21. MODEL ASSESSMENT The amount of hydrologic leakage caused by the post-processing filter depends on the filter smoothing and increases with large radius. It also depends on the hydrological model used. For DDK3 filter : the annual amplitude is between 7 - 28 mm in Mediterranean Sea and between 24 – 63 mm in Black Sea. the annual phase is between 30 - 53 degree in Mediterranean Sea and between 49 - 57 deg in the Black Sea. The semi-annual component is almost absent Figure 8: Hydrological leakage in the Mediterranean Sea (left) and the Black Sea (right) from different hydrology models. Intergeo, Geodätische Woche, 4-7 October 2010

  22. MODEL ASSESSMENT For WaterGAP3 : annual amplitude is in both regions smaller than in WaterGAP2 the annual phase is 10 degreees ahead Figure 9: Hydrological leakage in the Mediterranean Sea (left) and the Black Sea (right) from WaterGAP2 and WaterGAP3. Intergeo, Geodätische Woche, 4-7 October 2010

  23. MODEL ASSESSMENT GFZ solutions filtered DKK3 and re-scaled GAD restored GRGS solutions not filtered MOG2D and ATM not restored Figure 10: Ocean basin average of water mass change from GRACE/GFZ solutions corrected for the hydrology leakage usingWaterGAP3 (red) and WaterGAP2 (black), from steric-corrected altimetry (blue). The hydrology leakage is also shown (green) Intergeo, Geodätische Woche, 4-7 October 2010

  24. MODEL ASSESSMENT GFZ solutions filtered DKK3 and re-scaled GAD restored GRGS solutions not filtered, MOG2D and ATM not restored Ampl : 36 +/- 4 mm, ph: April (a-s) A: 46 +/- 4 mm, ph: 103 +/- 3 (Grace – WG2) Corr: 0.71 , Rms : 65 mm A: 63 +/- 4 mm, ph: 94 +/- 3 (Grace – WG3) Corr: 0.73 , Rms : 69 mm A: 49 +/-4 mm, ph:107 +/- 2 deg (Grace–WG2) Corr: 0.79 , Rms : 45 mm A: 70 +/- 4 mm, ph: 70 +/- 3 (Grace–WG3) Corr: 0.80 , Rms : 50 mm Figure 10: Ocean basin average of water mass change corrected for hydrology leakage Using WG3 (red) and WG2 (black), steric-corrected altimetry (blue). Hydrology leakage in green. Intergeo, Geodätische Woche, 4-7 October 2010

  25. Conclusions - A new regional model WaterGAP3 has been produced and validated at different levels - Hydrology: WaterGAP3 is better than WaterGAP2 for most river basins WaterGAP3 cumulated inflow is closer to reported values than WaterGAP2. - Oceanography : WaterGAP3 changes in river run-off influences the vertical structure of the NEMO model, not the horizontal which is mainly driven by wind. - GRACE and altimetry: Mass change derived from GRACE corrected for the leakage estimated from WaterGAP3 is in good agreement with steric-corrected sea level. Smaller RMS using the GRGS GRACE fields. No significant improvements wrt results obtained using WaterGAP2 Intergeo, Geodätische Woche, 4-7 October 2010

  26. Outlook Interaction & coupling of the dedicatedregional hydrology & ocean models - • Data assimilation plays a very important role in constraining the models • - The closure error validates mass variation & transport estimates Open questions: 1. GRACE: which are the real spatial resolution limits of mass change estimation? 2. DE-ALIASING: what is the impact of different de-aliasing on the solutions? We will evaluate it using our regional models in the de-aliasing. 3. CORRECTIONS: the atmospheric correction applied to altimetry (MOG2D) is not fully compatible with corrections/de-aliasing used in GRACE. What is the effect on the two estimations of mass change? 4. OCEANOGRAPHY/HYDROLOGY: how to validate the models after data assimilation? 5. HYDROLOGY: GRACE cannot distinguish between different hydrological compartements. Can we separate the different compartments using external information? Intergeo, Geodätische Woche, 4-7 October 2010

  27. The End Intergeo, Geodätische Woche, 4-7 October 2010

  28. Extra Viewgraphs - Intergeo, Geodätische Woche, 4-7 October 2010

  29. Contribution/deficits Dippetz 2010, STREMP/DFG • GRACE data contribute to the: • 1. estimation of ocean water mass variation • 2. of straits flow • 3. of mass variation on land • 4. of steric component by combination with altimetry • 5. improved understanding of space-temporal dynamical processes in terrestrial hydrological • systems by assimilation of GRACE data • 6. improved ocean model by conditions on water mass variation • ALTIMETRY data contribute to: • 1. + 2. independently from GRACE • 3. Improvement of ocean model by assimilation of altimetry • GOCE data contribute, with MSL from altimetry, to the estimation of : • Mean Dynamic Topography and Ocean Circulation • Deficit of satellite products: • 1. GRACE has low spatial resolution • 2. Atmospheric corrections for GRACE (GAD) not fully compatible with MOG2D correction • used by altimetry, how to make mass estimation fully compatible? • 3. GRACE cannot distinguish between different hydrological compartements (z.B. • Masstransport on the ground or in the Atmosphere) Intergeo, Geodätische Woche, 4-7 October 2010

  30. Contribution/deficits Poster Heidelberg 2009, Topo_Europe 4. Attenuation of the signal associated to truncation and filtering procedures Factor=1,25 (truncation to d/o 70 and no filtering) Factor=1,62 (Gaussian smoothing with radius 300 km) Rescaling parameter Method 1: assumes uniform layer of 1 cm, mean of averaging kernel Method 2: ratio of unfiltered and filtered steric-corrected altimetry Dumping factors are 1.39 for method 1 with the anisotropic filter DDK3 (Kusche, 2009) and 1.54 for method 2. Figure 3. Basin kernel unfiltered truncated (d70, d100) and smoothed with Gaussian (w300) and anisotropic (d12) Intergeo, Geodätische Woche, 4-7 October 2010

  31. Contribution/deficits Poster Heidelberg 2009, Topo_Europe Attenuation Truncation has the smallest effect, that depends on the d/o of the truncation. When smoothing is applied, the damping factor is not sensitive to degree and order of the expansion, it is sensible to the radius used. 5. Leakage of the hydrology signal on water mass estimation : corrected using models 2. De-aliasing Products in GRACE Are mass estimations from hydrology-corrected GRACE and steric-corrected altimetry fully compatible? Atmospheric corrections for GRACE (GAD) not fully compatible with MOG2D correction used by altimetry, MOG2D-G : high frequency de-aliasing product ( frequency > 20 days) used to de-aliase GRGS/BGI solution BUT different version as MOG2D-G in DAC (z.B. NOT defined in Black Sea) not available as 6 h product DAC (AVISO) : Dynamic atmospheric Corrections (DAC) by CLS using the Mog2D model, available as 6h products by AVISO includes the MOG2D-G (HF) and the ib correction (Low Frequency) Intergeo, Geodätische Woche, 4-7 October 2010

  32. Recipes and Inconsistencies: D/o for GAX? From 0 (Chambers) or from 2 (GFZ doc) De-aliasing Products in GRACE GFZ Figure 4. GAD, GAB and GSM monthly mean in Mediterranean Sea (left) and in the Black Sea (right) starting from degree 2 Intergeo, Geodätische Woche, 4-7 October 2010

  33. De-aliasED GRACE Solutions Figure 5. Basin means of the de-aliased GRACE fields provided by GFZ (black, filtered), IGG (red) and GRGS (blue) in Mediterranean (left) and Black sea (right) Intergeo, Geodätische Woche, 4-7 October 2010

  34. Figure 15. Basin average of de-seasonalized seawater mass anomalies from filtered steric-corrected altimetry (circle) and from hydrology-corrected GRACE (triangle). The GIA correction has been applied Intergeo, Geodätische Woche, 4-7 October 2010

  35. Figure 16. (Left): net flux –at Gibraltar derived from mass change, Evaporation, Precipitation, River Runoff in Mediterranean Sea and from net flux from Black Sea, (Right): Net flux at Bosphorus derived from mass change, Evaporation, Precipitation and River Run-off in Black Sea Intergeo, Geodätische Woche, 4-7 October 2010

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