1 / 21

GRACE Mascons and Hydrological Data for the Continents: GRACE ACCESS

GRACE Mascons and Hydrological Data for the Continents: GRACE ACCESS. D. Rowlands (1) , F. Lemoine (1) , S. Luthcke (1) , S. Klosko (2) , D. Chinn (2) , K. Akoumany (2) , A. Griffin (2) , M. Rodell (3) (1) Plantary Geodynamics Laboratory, Code 698, NASA/GSFC, Greenbelt MD USA 20771

hashim-torres
Download Presentation

GRACE Mascons and Hydrological Data for the Continents: GRACE ACCESS

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. GRACE Mascons and Hydrological Data for the Continents: GRACE ACCESS D. Rowlands(1) , F. Lemoine(1), S. Luthcke(1), S. Klosko(2), D. Chinn(2), K. Akoumany(2), A. Griffin(2), M. Rodell(3) (1) Plantary Geodynamics Laboratory, Code 698, NASA/GSFC, Greenbelt MD USA 20771 (2) SGT Inc., 7701 Greenbelt Rd, Greenbelt MD USA 20770 (3) Hydrological Sciences Branch, NASA/GSFC, Greenbelt MD USA 20771 GRACE Science Team Meeting Potsdam, October 2007 .

  2. Overview of Project Goals • GOAL: Make available through www access, high resolution estimates of mass flux/change from GRACE that provide important measures of the entire hydrological signal • Employ a standard 4x4 degree grid over continental regions and provide mass flux estimates (in units of cm of water) as a surface mass anomaly. These values are obtained every 10 days over a significant portion of the GRACE mission • Provide auxiliary estimates of the hydrological signal as available from state-of-the-art assimilative hydrological models (e.g. GLDAS) http://grace.sgt-inc.com

  3. Groundwater Flux is a Major Societal Concern Aquifers are being depleted in scores of countries which collectively account for half of the world grain harvest. Overpumping has largely depleted the shallow aquifers, so the amount of water that can be pumped from it each year is restricted to the annual recharge from precipitation. This is forcing well drillers to go down to the region's deep aquifer, which, unfortunately, is not replenishable http://grace.sgt-inc.com

  4. MASCON Approach • We directly estimate mass change in 4°x4° blocks – as geographically specific mascons (as opposed to global coefficients that are used to reconstruct mass change locally) • We directly estimate mass change every 10 days (as opposed to every 30 days) • We smooth our solutions by combining spatial and temporal constraint equations together with the GRACE tracking data in a simultaneous solution (as opposed to Gaussian smoothing gravity solution products a posteriori) • Only the precise KBRR tracking data is utilized in the our mascon solutions (as opposed to using both GPS and KBRR data) http://grace.sgt-inc.com

  5. GRACE Data Processing: Standards for Current Products • Gravity model: GGM02C (vs. GGM01C). • Atmospheric Gravity Series: • Based on NCEP Reanalysis by L. Petrov. • 2.5° x 2.5° and 6 hour resolution (0.25°x 0.25° land mask). • Consistent series from 1976------> Present (few days latency). • 50x50 spherical harmonic expansion @ 6 hours. • • Ocean tide modelling (e.g. M2 to 70x70; • Other major constituents to 50x50), (GOT00.2) • • Improved processing of GRACE accelerometry. • Reprocessing underway with updated background models (e.g. ECMWF 3-hr; GOT4.7b…..)

  6. Mississippi River Basin: Water Storage Variations GLDAS model average soil moisture + snow Ground water from well observations Observed ground water + GLDAS average soil moisture + snow Matt Rodell Hydrological Sciences Branch, NASA GSFC

  7. Mississippi Basin: GRACE mascon vs hydrology cross correlation ρ=+o.85 RMS = 2.9cm http://grace.sgt-inc.com

  8. GRACE Hydrology ACCESS Site:4°x4° Mascon Solutionsfor all Continental Regionshttp://grace.sgt-inc.com/

  9. India / South Asia

  10. Eastern Australia 4cm

  11. Australia: Lat -28, Long 146 GRACE Hydrology 4cm Linear = -0.85 cm/y Linear = -1.40 cm/y rms 1.83 cm rms 1.86 cm

  12. North Central Australia 15 cm

  13. Australia: Lat -16, Long 134 GRACE Hydrology 20 cm rms 4.2 cm Annual amp 5.7 cm phase 1 day Semi-annual amp 1.7 cm phase -12 day rms 5.1 cm Annual amp 11.3 cm phase 0 day Semi-annual amp 2.7 cm phase -14 day

  14. Sahara 4 cm

  15. Amazon Basin 40 cm

  16. NASA ACCESS Program: Generation of Gridded Hydrological Mass Anomalies: Cross Correlation with GLDAS

  17. Coherence Spectrum Between GRACE 4o Mascons and Coincident NOAH Hydrology

  18. Optimal Phase Shift Between Hydrology and GRACE (239 N. American 4o Cells)

  19. 4 Year Time Series is Now Available

  20. Summary ◙GRACE KBRR tracking has provided the means to monitor global changes in the hydrological column ◙10-day estimates of 4 x 4 degree mass anomalies having accuracy assessments of 1-2 cm (equivalent water height) are available for both GRACE and coincident hydrological model –GLDAS ◙ The GRACE ACCESS site is at HTTP://GRACE.SGT-INC.com. ◙ Data are provided for a four year time period allowing comparison of the annual and semi-annual cycles repeatedly over each region. ◙These data are easily downloadable and a toolkit is provided to performvarious analysis functions on-line. ◙Future upgrades to the GRACE solutions, extended times series, and enhanced toolkit are planned

More Related