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IGCP565 and AfricaArray Workshop

IGCP565 and AfricaArray Workshop. (1) University of Bonn, (2) University of Frankfurt, (3) GFZ Potsdam. Standard and non-standard GRACE products for hydrology Jürgen Kusche (1) , Ehsan Forootan (1) , Annette Eicker (1) , Enrico

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IGCP565 and AfricaArray Workshop

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  1. IGCP565 and AfricaArray Workshop (1) University of Bonn, (2) University of Frankfurt, (3) GFZ Potsdam Standard and non-standard GRACE products for hydrology Jürgen Kusche(1), Ehsan Forootan(1), Annette Eicker(1), Enrico Kurtenbach(1),Anno Löcher(1), Petra Döll(2), Frank Flechtner(3) SPP 1257 “Mass Transport and Mass Distribution”

  2. Outline • GRACE status • GRACE science results • GRACE standard products & how to use them • GRACE non-standard products & procedures • Beyond GRACE SPP1257 „Mass Transport and Mass Distribution in the System Earth“ is supported by Germany‘s national funding agency DFG

  3. GRACE Status GRACE Mission Facts • highly successful US/German twin-satellite mission launched in 2002, to monitor mass transport and mass distribution in system Earth • PI: Byron Tapley (University of Texas, Center for Space Research), Co-PI: Dr. Frank Flechtner (GFZ Potsdam) • Will celebrate 10th birthday on March 17, 2012 • Will likely end its operation in the next 1-3 years (depending on battery status and solar activity) April 2011: 2700 users registered at GFZ/ISDC (16% from Germany/China/USA each) 700+ publications (many Nature/Science)

  4. GRACE Status GRACE has initiated interdisciplinary research between hydrologists, glaciologists, oceanographers, geophysicists, geodesists. Major breakthroughs in the understanding of • changes in the terrestrial water cycle (water storage, exchange and depletion), • melting and growing of glaciers, Greenland and Antarctic ice sheets, • sea level rise and what contributes to it (mass or volume change), • and solid Earth (past glaciation and deglaciation, Earthquakes) DFG SPP1257 „Mass Transport and Mass Distribution in the System Earth“ • Largest interdisciplinary research program (~50PhD positions for 6 years) • www.massentransporte.de • AGU Fall Meeting: session G11 "Mass transport in the Earth system"

  5. GRACE Status GRACE Mission Facts Generation of GRACE Standard L1a/b Products (Flechtner 9/11)

  6. GRACE Status GRACE Health Status • Degraded battery capacity (cell failure) • Every 161 days (Sun in orbital plane), battery use is limited ( maximize lifetime) • http://www.csr.utexas.edu/grace/operations/mission_status/ GRACE SDS Newsletter 9/2011: Level-2 gravity field determination

  7. GRACE Science Results Sea Level – decomposing sea level rise into mass and steric change GSLR: altimetry = GRACE + Argo + deep ocean warming (Leuliette and Willis 2011, Oceanography) - using GRACE L2 standard products + postprocessing -

  8. GRACE Science Results Polar Ice Sheets and Glaciers Shrinking at increasing speed Schrama and Wouters (2011, JGR): -201Gt/y Ewert et al (acc., J Geodyn) -191Gt/y Shrinking at decreasing speed Greenland ice mass loss and sea level contribution (~0.5mm/a) - using GRACE L2 standard products + postprocessing -

  9. GRACE Science Results Solid Earth – Constraining seismic and fault models for large EQs Han et al. (2010, GRL): GRACE observes coseismic gravity effect of the M8.8 2010 Chile EQ - using non-standard products -

  10. GRACE Science Results Solid Earth – Constraining seismic and fault models for large EQs GRACE co-seismic PREM with ocean layer, two seismic source models Cambiotti et al. (2011, JGR): GRACE helps constraining seismic models of the 2004 Sumatra EQ - using standard L2 products + postprocessing (DDK3 decorrelation) -

  11. GRACE Science Results Hydrology –Grippa et al. (2011): TWS from 6 GRACE solutions, different post-processing, and 9 LSMs - multimodel averaging is difficult to justify - LSM GRACE

  12. GRACE Science Results Hydrology – Henry et al. (2011): GRACE TWS – GLDAS Soil moisure = Groundwater variation Avg. GW

  13. GRACE Science Results Hydrology – Becker et al. (2010, C.R. Geoscience)

  14. GRACE Data Products GRACE standard products • L2 level: Monthly spherical harmonic expansions of gravity potential V User interest (I) • „L3 level“: Monthly maps of equivalent water heights (can be derived from L2 standard products) User interest (II) • Enhance temporal and/or spatial resolution • Minimize leakage of mass variation outside area of interest • Combine with in-situ data •  Nonstandard products • Special L1-L2 processing approaches • Development of postprocessing

  15. GRACE Standard Products & How to use them Monthly sets of spherical harmonics. TWS from GRACE Issues • SH resolution • Latency and gaps • Processing • AOD-Products • Degree-1 and C20 Solid Earth Response (Love numbers/ Geophysical model) EWH maps

  16. GRACE Standard Products & How to use them Monthly sets of spherical harmonics • SH resolution – from a user point of view, desirable resolution depends on application • Latency – depends on latency of L1B products, is there really a need for low-latency products? • Gaps – procedures to deal with gaps still have to be developed. Altimetry community has experience with „reconstruction“ of fields. Can other data sources (superconducting gravimeters, SLR, GPS inversion) help? • Dealiasing procedure and products (next slides)

  17. GRACE Standard Products & How to use them Generation of GRACE Standard L2 Products (Flechtner 9/11)

  18. GRACE Standard Products & How to use them Generation of GRACE Standard AODB Products (Flechtner 9/11)

  19. GRACE Standard Products & How to use them Generation of GRACE Standard AODB Products (Flechtner 9/11)

  20. GRACE Standard Products & How to use them Monthly sets of spherical harmonics – AOD products Recommended use of GRACE Standard AODB Products (Flechtner 9/11)

  21. GRACE Standard Products & How to use them Monthly sets of spherical harmonics – AOD products For hydrology applications: • No need to restore AOD product • WARNING: AOD is not consistent with IB correction in altimetry, this has to be considered when combining GRACE and lake/coastal altimetry Recommended use of GRACE Standard AODB Products (Flechtner 9/11)

  22. GRACE Standard Products & How to use them Degree-1 (C10.C11,S11): add from other data sources Geocenter motion (Rietbroek et al. 2011) EWH corresponding to degree 1 (Swenson & Wahr 2007)

  23. GRACE Standard Products & How to use them Degree-1 and C20 (Flechtner, 9/11)

  24. GRACE Non-Standard Products & Procedures Enhanced temporal resolution • Daily GRACE solutions • Weekly GRACE solutions • Monthly GRACE solutions Enhanced spatio-temporal resolution • Masscon solutions • RBF solutions Multisensor combination products • GRACE/GPS/OBP Post-processed products • Decorrelated solutions • Maps of rates, accelerations and annual components • Mode decompositions

  25. GRACE Non-Standard Products & Procedures From L1 data to L2/“L3“ data Geophysical model (loading) L1 data (KBR, GPS, ACC, ATT) Intermediate functional (LOS acc., potential difference, …) Gravity potential parameterization EWH parameterization Geophysical background models Earth‘s surface Satellite altitude Modified from Panet et al (2009)

  26. GRACE Non-Standard Products & Procedures Daily GRACE SH solutions (Bonn University, Kurtenbach et al, 2009) • Low spatial resolution but high temporal resolution • Not a combination, uses only stochastic constraints • Used as well in de-aliasing of ITG2010 monthly solutions

  27. GRACE Non-Standard Products & Procedures Daily GRACE SH solutions (Bonn University) • Low spatial resolution but high temporal resolution • Not a combination, uses only stochastic constraints • Used as well in de-aliasing of ITG2010 monthly solutions Weighted combination (Kalman-Filter/RTS-Smoother) 1-day prediction GRACE daily NEQs

  28. GRACE Non-Standard Products & Procedures Monthly GRACE SH solutions (Bonn University) • Using daily solutions for dealiasing (instead of AOD product) without with equivalent water height [cm]

  29. GRACE Non-Standard Products & Procedures Monthly GRACE SH solutions (Bonn University) – West Africa

  30. GRACE Non-Standard Products & Procedures Enhanced spatio-temporal resolution („regional“ approaches“, using regional constraints) • RBF solutions (Eicker, Holschneider,…) • Compute a harmonic gravity model (L2) with less base functions, avoiding SH expansion, L3 EWH using Love numbers • Masscon solutions (Rowlands, Ramillien, …) • Direct modelization of EWH (L3) or use of SH expansion • Basin-shaped „masscons“ (Wouters, Sandberg-Sørensen…) • Derived from gridded L2 products at altitude

  31. GRACE Non-Standard Products & Procedures RBF solutions (Eicker et al, Uni Bonn) • Compute a harmonic gravity model (L2) with less base functions, avoiding SH expansion, L3 EWH using Love numbers

  32. GRACE Non-Standard Products & Procedures Masscon solutions (standard 4ox4o, isotropic constraints) Krogh et al (2011), 10d x 1.5o/1.25o x 1o, regional constraints (RC) GLDAS 4o mascon GRGS-50 1.5o mascon mascon RC mascon RC-50

  33. GRACE Non-Standard Products & Procedures Fundamental difference: Implementation of constraints in the masscon approach (Rowlands et al 2010, Sabaka et al 2010)

  34. GRACE Non-Standard Products & Procedures Fundamental difference: Implementation of constraints in the RBF/Kalman filter approach (Eicker 2008, Kurtenbach 2011)

  35. GRACE Non-Standard Products & Procedures Post-processing of SH products • Gauss-filtering • Decorrelated/destriped solutions: Swenson and Wahr 2006, Kusche 2007 • Mode decompositions (EOF, ICA)

  36. GRACE Non-Standard Products & Procedures GRACE SHC SHA geophysical model  SHC Globally defined? Treatment degree 1 & 2, temporal anomalies wrt epoch t, restore AOD Temporal alignement, possibly remove deg. 1 consistent to GRACE Filtering (in spectral domain) Filtering (in spectral domain) Multiplication in spectral domain Mapping to space domain or basin averaging Mapping to space domain or basin averaging OR Filtering (in space domain) OR Filtering (in space domain) Convolution on the sphere

  37. GRACE Non-Standard Products & Procedures GRACE SHC Geophysical model Treatment degree 1 & 2, temporal anomalies wrt epoch t, restore AOD Temporal alignement, possibly remove deg. 1 consistent to GRACE Filtering (in spectral domain) Filtering (in spectral domain) Mapping to space domain or basin averaging Mapping to space domain or basin averaging Filtering (in space domain)

  38. Destriping filters GRACE Non-Standard Products & Procedures Swenson & Wahr 2006 Gridded destriped fields: GRACE Tellus site http://grace.jpl.nasa.gov/

  39. GRACE Non-Standard Products & Procedures Destriping filters Kusche 2007 („DDK filters“) Destriped models and grids: GFZ ICGEM site http://icgem.gfz-potsdam.de/ICGEM/

  40. Destriping filters and WRMS reduction GRACE TWS WRMS [cm], 3 filters GRACE Non-Standard Products & Procedures stronger filtering less

  41. GRACE Non-Standard Products & Procedures Post-processed products • Mode decompositions 1. Decompose the hydrological model into statistically independent regimes • begin with PCA • sacrify spatial orthogonality and employ higher-order statistics HOS ICA 2. Bin the GRACE TWS solutions into these statistically independent regimes Forootan & Kusche (accepted for J Geodesy)

  42. GRACE Non-Standard Products & Procedures Post-processed products • Mode decompositions Decomposition into statistically independent regimes (1. begin with PCA 2. sacrify spatial orthogonality and employ higher-order statistics HOS) E. Forootan

  43. Beyond GRACE GRACE-FO • NASA-DLR partnership (as with GRACE) • anticipated launch 15 November 2016 • Nominal lifetime 5 y, anticipated 7 y • Will carry • K-band ranging instrument (as with GRACE) • Laser ranging instrument as add-on Beyond GRACE-FO • e.motion proposal (ESA EE-8 call, not selected) • ESA NG2 studies • Multiple pairs of satellites (e.g. Bender configuration)? • Quality of background models?

  44. Beyond GRACE GRACE-FO • Will carry • K-band ranging instrument (as with GRACE) • Laser ranging instrument as add-on v v AEI, Hannover

  45. Beyond GRACE Science Requirements (from e.motion proposal) Signal amplitudes of mass variations in EWH as a function of spatial resolution, together with present-day and e.motion performance and resolution. Solid Earth mass variations are converted to EWH. Contributions from seasonal to interannual variations (left panel), and contributions from long-term trends (right panel).

  46. Beyond GRACE Gain from the next generation of gravity missions for hydrology and water management (from NG2 study): more & smaller basins ■■■■■■

  47. Take-home Message • GRACE has provided a unique opportunity for geodesy and hydrology • With GRACE-FO in reach, and developments starting for missions beyond, we‘re hopefully heading towards an operational chain of gravity/mass missions (as in altimetry) • Future missions will likely push the spatial resolution of GRACE down to 150-200km • Through a series of reprocessings and through development of non-standard products, GRACE product quality has strongly increased Thank you for your attention.

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