grace!and!grace!products!tutorial!! jeanne!sauber,!nasa… · 2015-07-17 · 180 190 200 210 220...
TRANSCRIPT
Thanks for the opportunity to get out of my NASA office
GRACE and GRACE Products Tutorial Jeanne Sauber, NASA Goddard Space Flight Center
J. Davis CIDER presentaFon, July 10, 2015
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Example satellite only, mean gravity field: -‐-‐GGMO5S, GRACE -‐-‐EIGEN-‐6S2 for GRACE Plo2er -‐-‐GOCO5S
Figure and capFon from hSp://earthobservatory.nasa.gov/Features/GRACE/page3.php
J. Davis CIDER presentaFon, July 10, 2015
Modified from J. Davis CIDER presentaFon, July 10, 2015
• Level 3 data of monthly surface mass changes of hydrologic, cryospheric, and oceanographic components.
KBR1B ex. Next slide
M 8.8 Maule Earthquake
Range-‐acceleraFon from individual satellite passes
Han, Sauber, Luthcke, GRL, 2011
Objec?ve: Contrast seismically derived early fault-‐slip models
Coseismic changes in range-‐rate March 11, 2011 Tohoku earthquake (M 9.2)
Han, Sauber, Riva, GRL, 2011
Interac(ve GRACE web site used in tutorial for visualizing solu(ons:
hSp://www.thegraceploSer.com/ DocumentaFon on “background” models for this site:
hSp://grgs.obs-‐mip.fr/grace
See JPL GRACE Tellus Project Web Site for links to different type soluFons & downloading data:
hSp://grace.jpl.nasa.gov/
hSp://podaac.jpl.nasa.gov/datasetlist?search=GRACE
NOTE: We start with the “Trend CNES” opFon with “water heights” Gravity funcFonal.
"Made with www.thegraceploSer.com, courtesy of CNES/GRGS"
# Linear model: Trend: -‐13.669 cm/year RMS of residuals (series-‐model): 19.193 cm
Periodic model: Least square adjustment: y=A+B(t-‐t0) +Ccos(ω(t-‐t0))+Dsin(ω(t-‐t0))+Ecos(2ω(t-‐t0))+Fsin(2ω(t-‐t0))
Annual amplitude: 22.14 cm
"Made with www.thegraceploSer.com, courtesy of CNES/GRGS"
Land ice mass evoluFon from GRACE
GSFC Mascon soluFon, Luthcke et al., J. of Glaciology, 2013 11
• 41,168 equal area 1-‐arc-‐degree mascons are directly esFmated from GRACE KBRR L1B data with spaFal and temporal exponenFal taper constraints applied.
• 10-‐day temporal resoluFon
• Spa(al constraint: 100 km correlaFon distance
• Temporal constraint: 10-‐day correlaFon
• Gulf of Alaska glacier region (61 mascons)
Gt Overall G of Alaska Trend = -‐69 ± 11 Gt a-‐1
Note variability in peak to peak seasonal amplitude and annual net balance (2005 versus 2012 balance year).
Gulf of Alaska
cm w.e.
Mascon 1484: North Central Smaller seasonal, 25-‐50 cm w.e. (peak to peak) Moderate 10-‐year trend
Mascon 1457: Central Coastal Moderate seasonal, 50-‐75 cm w.e., (peak to peak); Largest 10-‐year trend
Gt
Year
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Mascon 1425, South Eastern Alaska: Large seasonal: up to 100 cm w.e. (peak to peak) Large LiDle Ice Age PGR/GIA removed; Small 10 year-‐trend
SE
NC
Gulf of Alaska
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1425
1484
1457
CC
The differences in GRACE-‐derived seasonal changes are disFnct from region to region and from year to year.
GRACE MASCONS located adjacent or < 200 km to other mascons
1449
1457
1456
cm w.e.
Reminder: GRACE is sensi(ve to changes at spa(al scales > 300km
180 190 200 210 220 230 24040
45
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55
60
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75
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−1
−0.5
0
0.5
1Postseismic gravity change in EWH [cm/yr]
Epicenter of the 1964 Alaska earthquake
~1 cm/yr
Simula?on of the present-‐day postseismic gravity change 1964 Mw = 9.2 Prince William Sound (Alaska) earthquake
-‐ Used Johnson et al. [1996] finite fault model: inversion of tsunami and geodeFc data to esFmate 1964 coseismic slip
-‐ We used the viscoelasFc Earth model that is consistent with other studies in this region [Suito and Freymueller, 2009; Sato et al., 2010]
-‐ Global normal mode relaxaFon code was used to compute the gravity change over the period 2002 -‐ 2014. (Courtesy of R. Riva and F. Pollitz)
=> ~1 cm/yr of gravity change (in w.e.) is predicted, primarily dependent on the asthenosphere viscosity (1019 Pa s)
Spherical harmonic coefficients from RL05 CSR L2 monthly data, degree up to 60; ~330 km resoluFon.
SchemaFc
Time-‐series at the epicenter (60N 212W)
2004 2006 2008 2010 2012 2014−80
−60
−40
−20
0
20
40
60
80
Year
Gra
vity
chan
ge in
EW
H [c
m]
GRACE RL05 L2 (CSR)Seasonal & secular fitSecular trend1964 EQ effect
GRACE secular trend ~ –8.3 cm/yr (observed RL05 CSR L2 ) 1964 EQ postseismic change ~ +1.0 cm/yr (model predicted)
The postseismic gravity change could be as large as 10% of the observed mass change, even 50 years a{er the 1964 earthquake.