grace science team meeting+dfg schwerpunktprogramm 1257 symposium, 15-17. september 2007 saskia...
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Grace Science Team Meeting+DFG Schwerpunktprogramm 1257 Symposium, 15-17. September 2007
Saskia Esselborn, Andrea Homberg, Tilo Schöne and Roland Schmidt
GFZ Potsdam
Basin Scale Mass Variations in the Atlantic Ocean
from Altimeter, in situ and GRACE Data
Grace Science Team Meeting+DFG Schwerpunktprogramm 1257 Symposium, 15-17. September 2007
Total: Jason-1Steric: Argo drifter Mass specific: GRACE
Grace Science Team Meeting+DFG Schwerpunktprogramm 1257 Symposium, 15-17. September 2007
DataMonthly mean deviations 2002 to April 2007 (52 months
common), spatial Hamming filter (700 km half length width)
• Altimeter: Jason-1, state of the art correction models, updated radiometer correction, JGN3 orbit
• GRACE: GFZ-RL04, water level equivalent, monthly GAB-correction readded, geocenter motion correction from GPS (Heflin, JPL)
• In-situ data (steric): gridded Argo data, level of no motion at 1950 m (CORIOLIS project, Ifremer)
Grace Science Team Meeting+DFG Schwerpunktprogramm 1257 Symposium, 15-17. September 2007
RMS [cm]
Jason-1 Argo
Grace Science Team Meeting+DFG Schwerpunktprogramm 1257 Symposium, 15-17. September 2007
RMS [cm]
GRACE
3
Jason-1 minus Argo
6
Grace Science Team Meeting+DFG Schwerpunktprogramm 1257 Symposium, 15-17. September 2007
Mean Sea Level North Atlantic
Blue: total (Jason-1)Purple: total (steric+mass)
Red: steric (Argo)Green: mass (GRACE)
Grace Science Team Meeting+DFG Schwerpunktprogramm 1257 Symposium, 15-17. September 2007
RMS [cm] annual cycle substracted
ArgoJason-1
Grace Science Team Meeting+DFG Schwerpunktprogramm 1257 Symposium, 15-17. September 2007
RMS [cm] annual cycle substracted
GRACE
3
Jason-1 minus Argo
6
Grace Science Team Meeting+DFG Schwerpunktprogramm 1257 Symposium, 15-17. September 2007
Annual cycle Amplitude [cm]
ArgoJason-1
Grace Science Team Meeting+DFG Schwerpunktprogramm 1257 Symposium, 15-17. September 2007
Annual cycle Amplitude [cm]
GRACE
3
Jason-1 minus Argo
6
Grace Science Team Meeting+DFG Schwerpunktprogramm 1257 Symposium, 15-17. September 2007
Crosscorrelationexplained variance [%]
Jason-1 minus Argo,GRACEJason-1, Argo Jason-1, GRACE
75 60
Grace Science Team Meeting+DFG Schwerpunktprogramm 1257 Symposium, 15-17. September 2007
Crosscorrelationwithout annual cycle
Jason-1 minus Argo,GRACEJason-1, Argo Jason-1, GRACE
Grace Science Team Meeting+DFG Schwerpunktprogramm 1257 Symposium, 15-17. September 2007
Subtropics
Subpolar
Subtropics
Subpolar
Grace Science Team Meeting+DFG Schwerpunktprogramm 1257 Symposium, 15-17. September 2007
Mass related sea level deviations
Red: GRACEBlue: Jason-1 minus Argo (total-steric)
Grace Science Team Meeting+DFG Schwerpunktprogramm 1257 Symposium, 15-17. September 2007
Sea level deviations
Blue: total (Jason-1)Purple: total (steric+mass)
Red: steric (Argo)Green: mass (GRACE)
NA Subtropics NA Subpolar
Grace Science Team Meeting+DFG Schwerpunktprogramm 1257 Symposium, 15-17. September 2007
Trends mm/year
SAtlantic NAtlantictotal (Jason-1) 4.6 0.6steric (Argo) 1.4 0.2mass (GRACE) -0.2 1.1mass (GRACE ) -0.6 0.4without geocenter correction
Grace Science Team Meeting+DFG Schwerpunktprogramm 1257 Symposium, 15-17. September 2007
Sea level differences [cm]
Blue: total (Jason-1)Green: mass (GRACE)
South Atlantic minus North Atlantic SAtlantic Subtropics minus Subpolar
Grace Science Team Meeting+DFG Schwerpunktprogramm 1257 Symposium, 15-17. September 2007
Summary• Good agreement between total and steric sea level for
most areas and times• Argo: Problems with data coverage and bias/trend,
improvements expected soon• Mass related sea level from altimetry and Argo data is
probably less accurate than GRACE data• Geocenter correction influences the trend estimation
from GRACE data• Agreement between the three data sets is sufficient for
most times in the subpolar and subtropic North Atlantic• Total and mass related sea level difference between
North and South Atlantic is in phase