observing mass variability in the earth system with the ......time-variations in terrestrial water...

1Time-Variations in Terrestrial Water Storage from GRACE and GRACE-FO

Henryk Dobslaw and Frank FlechtnerGFZ German Research Centre for Geosciences,

Potsdam, Germany

Observing Mass Variability in the Earth System with the Satellite Gravity Missions GRACE and GRACE-FO


GRACE: Concept of Gravity Field Monitoring

range: σs = 5 µm

(a tenth of the thickness of a human hair)

range-rate: σds/dt = 0.1 µm/s

nominal distance: s = 220 ± 50 km

1/rev separation change: ±2 km

(primarily flattening of the Earth)

signals-of-interest: ±200 µm


Science Objectives: Mapping Global Mass Re-DistributionsTectonics: Co- and Post-Seismic Deformations

Han et al. (2006), Science

Oceans: Barystatic Sea-Level Changes

IPCC Fifth Assessment Report (2014)

Land: Terrestrial Water Storage

Rodell et al. (2009) Nature


Secondary Science Objective: GPS Radio Occultations

GRACE


GRACE Sensor Data Processing (Level-1)

Observation of gravitationally caused orbit perturbations along the common line of sight of a twin satellite pair by • high-low (GPS) and• low-low (K-Band)

Satellite-to-Satellite Tracking (SST)

Observation of non-gravitational accelerations by3D Accelerometer (SuperSTAR)

Observation of the satellite and instrument orientation by Star Cameras

Validation of GPS-derived orbit by Satellite Laser Ranging (SLR)


GRACE Gravity Processing (Level-2) at GFZ

www.gfz-potsdam.de/grace Dahle et al. (2012)

O(10-4)


GRACE Mass Data Processing (Level-3) at GFZ

www.gfz-potsdam.de/gravis Zhang et al. (2016)

JJA

DJF MAM

SON

TWS [m]


GRACE Mass Data Processing (Level-3) at GFZ

www.gfz-potsdam.de/gravis Zhang et al. (2016)

2008

2003 2007

2015

TWS [m]


Regional Terrestrial Water Balance

ΔTWS(t) = Total Water Storage

ΔSWE(t) = Snow Water EquivalentΔSW(t) = Surface WaterΔSM(t) = Soil MoistureΔGW(t) = Ground Water

P(t) = PrecipitationET(t) = Evapotranspiration R(t) = Runoff

can be provided by GRACE only!

ΔTWS(t) = ΔGW(t) + ΔSW(t) + ΔSWE(t) + ΔSM(t) = P(t) – ET(t) - R(t)


Characterizing California Drought

Monthly water storage variations

Climatology

Anomalies from climatology

drought begins drought ends

Deficit is 45 km3 in November 2008Deficit is 45 km3 in March 2014

Famiglietti et al. (2014)


Secular Trends in Terrestrial Water Storage from GRACE

Antarctic ice sheet melting

Patagonia glaciers melting

Alaska glaciers melting

Greenland ice sheet melting

Southeastern U.S. drought

NW Australiagroundwater depletion

Orinoco and Amazonfloods

India/Bangladesh groundwater depletion

Indian monsoon

Central Valleygroundwater depletion Middle East groundwater depletion

North China Plaingroundwater depletion

High Plains Aquifergroundwater depletion

UpperMidwest U.S. flooding

North Africagroundwater depletion

High latitude precipitation increase

Caspina/AralSeas shrinking

Southern Africagroundwater depletion

Mekong drought

Brazil droughtPeru glaciers melting

Guarani Aquifer groundwater depletion

Congo droughtColombia glaciers melting

West Africafloods

Okavangofloods

Ukraine drought


Do We Have a Global Water Crisis?


Flood and Drought Information in Near-Realtime

Gouweleeuw et al. (2017)www.egsiem.eu


Analyzing P-ET Deficits in Gauged Catchments

Springer et al. (2016)


GRACE Contributions to Snow Mass Observations

Behrangi et al. (2016)

TibetanPlateau


Data Assimilation of GRACE-Based TWS

Eicker et al. (2014)


GRACE-FO Launch Date: March 21st, 2018

Space-X Falcon-9 rideshare with Iridium-Next

Contributions to the LRI

Mission Operations(Subcontract to DLR/GSOC)

Laser Retro-Reflectors(redundant orbit determination)

Gravity and Mass Anomaly Processing (within joint US/D Science Data System)


GRACE-based Terrestrial Water Storage - Essentials

• Satellite Gravimetry with GRACE and GRACE-FO is the only remote sensing system that monitors mass transport across the whole globe

• Terrestrial Water Storage is sensed independently of its surface exposure

• monthly estimates with a spatial resolution of ~500 km and global coverage

• GRACE has delivered 15.5 years of global monthly gravity fields (2002 – 2017)

• GRACE Follow-On launch is planned for March 21st, 2018

• GRACE provides the storage term in the terrestrial water balance equation: storage changes as indicators for water availability estimating P-E deficits over gauged basins contributions to snow mass observations growing number of data assimilation experiments

[email protected]


Geophysical Signal Separation

Ilk et al. (2004)


Atmosphere: Surface PressureC11

3-hourly tendencies

Dobslawet al. (2017)


Atmosphere: Surface Pressure Uncertainties



Atmosphere: Upper-Air Contributions



Glacial Isostatic Adjustment

Klemann et al. (2012)


Co- and Post-Seismic Deformations

10 cm in EWH

2004 2014

M9.1M8.6

M9.1

M8.6

1000 km

cmEWH

Courtesy Y. Tanaka(ERI, U. Tokyo)


Large-Scale Erosion and Sedimentation

Liu et al. (2016)

observing mass variability in the earth system with the ......time-variations in terrestrial water...

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