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Seasonal variation of ocean bottom pressure derived from GRACE: Local validation and global patterns

Seasonal variation of ocean bottom pressure derived from GRACE: Local validation and global patterns
Seasonal variation of ocean bottom pressure derived from GRACE: Local validation and global patterns
The Gravity Recovery and Climate Experiment (GRACE) processing centers at the GeoForschungsZentrum Potsdam (GFZ) and the University of Texas Center for Space Research (UTCSR) provide time series of monthly gravity field solutions covering the period since mission launch in March 2002. Although the achieved accuracy still remains an order of magnitude below the mission's baseline goal, these time series have successfully been used to study terrestrial phenomena such as water storage variations. Over the oceans, the monthly gravity field solutions can be converted into estimates of the fluctuating ocean bottom pressure (OBP), which is the sum of atmospheric and oceanic mass variations. The GRACE products may be validated against in situ OBP observations which are available from a ground truth site in the tropical northwest Atlantic Ocean. Large differences are observed between the in situ and GRACE-derived OBP which are investigated by comparing the tidal and nontidal ocean models used at GFZ and UTCSR for dealiasing short-term (<2 months) mass variations from satellite measurements. Results show that the barotropic nontidal and tide models need improvement at periods shorter than 1 day and longer than 2 weeks. On a global scale the monthly OBP fields from GRACE generally overestimate the variability compared to ocean general circulation models, especially in tropical regions. This may be attributed to continuing deficiencies in GRACE data processing. Nevertheless, there is some initial evidence that GRACE possesses the potential to observe large-scale averages of bottom pressure fluctuations.
gravity, geoid, ocean bottom pressure, deep ocean currents, ocean tides, in situ measurements
0148-0227
C09001
Kanzow, T.
ede4d92e-c4b2-48d0-83bf-a03f881aa819
Flechtner, F.
caa3d7a0-aa7d-45ce-aa0e-ecd26466dfa6
Chave, A. D.
3717cde9-0f28-4f75-8458-40ac7ec1dfa1
Schmidt, R.
8a51f12b-8cdd-496f-bb6a-41127310d191
Schwintzer, P.
2f5b64c9-3705-444a-9f3e-fa94e1a2b680
Send, U.
e4f7234f-b5b3-4472-a57e-d15bc1e2c2a2
Kanzow, T.
ede4d92e-c4b2-48d0-83bf-a03f881aa819
Flechtner, F.
caa3d7a0-aa7d-45ce-aa0e-ecd26466dfa6
Chave, A. D.
3717cde9-0f28-4f75-8458-40ac7ec1dfa1
Schmidt, R.
8a51f12b-8cdd-496f-bb6a-41127310d191
Schwintzer, P.
2f5b64c9-3705-444a-9f3e-fa94e1a2b680
Send, U.
e4f7234f-b5b3-4472-a57e-d15bc1e2c2a2

Kanzow, T., Flechtner, F., Chave, A. D., Schmidt, R., Schwintzer, P. and Send, U. (2005) Seasonal variation of ocean bottom pressure derived from GRACE: Local validation and global patterns. Journal of Geophysical Research, 110 (C9), C09001. (doi:10.1029/2004JC002772).

Record type: Article

Abstract

The Gravity Recovery and Climate Experiment (GRACE) processing centers at the GeoForschungsZentrum Potsdam (GFZ) and the University of Texas Center for Space Research (UTCSR) provide time series of monthly gravity field solutions covering the period since mission launch in March 2002. Although the achieved accuracy still remains an order of magnitude below the mission's baseline goal, these time series have successfully been used to study terrestrial phenomena such as water storage variations. Over the oceans, the monthly gravity field solutions can be converted into estimates of the fluctuating ocean bottom pressure (OBP), which is the sum of atmospheric and oceanic mass variations. The GRACE products may be validated against in situ OBP observations which are available from a ground truth site in the tropical northwest Atlantic Ocean. Large differences are observed between the in situ and GRACE-derived OBP which are investigated by comparing the tidal and nontidal ocean models used at GFZ and UTCSR for dealiasing short-term (<2 months) mass variations from satellite measurements. Results show that the barotropic nontidal and tide models need improvement at periods shorter than 1 day and longer than 2 weeks. On a global scale the monthly OBP fields from GRACE generally overestimate the variability compared to ocean general circulation models, especially in tropical regions. This may be attributed to continuing deficiencies in GRACE data processing. Nevertheless, there is some initial evidence that GRACE possesses the potential to observe large-scale averages of bottom pressure fluctuations.

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More information

Published date: 2005
Keywords: gravity, geoid, ocean bottom pressure, deep ocean currents, ocean tides, in situ measurements

Identifiers

Local EPrints ID: 47042
URI: http://eprints.soton.ac.uk/id/eprint/47042
ISSN: 0148-0227
PURE UUID: c3857d9a-26e2-492c-b419-9150ed8d05fd

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Date deposited: 24 Jul 2007
Last modified: 15 Mar 2024 09:29

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Contributors

Author: T. Kanzow
Author: F. Flechtner
Author: A. D. Chave
Author: R. Schmidt
Author: P. Schwintzer
Author: U. Send

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