Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 9 of 9
Full-Text Articles in Entire DC Network
Ocean Mass From Grace And Glacial Isostatic Adjustment, D. Chambers, John Wahr, Mark E. Tamisea, R Steven Nerem
Ocean Mass From Grace And Glacial Isostatic Adjustment, D. Chambers, John Wahr, Mark E. Tamisea, R Steven Nerem
Marine Science Faculty Publications
We examine geoid rates and ocean mass corrections from two published global glacial isostatic adjustment (GIA) models, both of which have been used in previous studies to estimate ocean mass trends from Gravity Recovery and Climate Experiment (GRACE) satellite gravity data. These two models are different implementations of the same ice loading history and use similar mantle viscosity profiles. The model results are compared with each other and with geoid rates determined from GRACE during August 2002 to November 2009. When averaged over the global ocean, the two models have rates that differ by nearly 1 mm yr−1 of …
Hydrological And Oceanic Effects On Polar Motion From Grace And Models, Shaunggen Jin, Don Chambers, Byron D. Tapley
Hydrological And Oceanic Effects On Polar Motion From Grace And Models, Shaunggen Jin, Don Chambers, Byron D. Tapley
Marine Science Faculty Publications
Terrestrial water storage (TWS) and ocean bottom pressure (OBP) are major contributors to the observed polar motion excitations, second only to atmospheric mass movement. However, quantitative assessment of the hydrological and oceanic effects on polar motion remains unclear because of the lack of global observations. In this paper, hydrological and oceanic mass excitations to polar motion are investigated using monthly TWS and OBP derived from the Gravity Recovery and Climate Experiment (GRACE) for January 2003 until December 2008. The results from this analysis are compared with hydrological model excitations from the European Center for Medium-Range Weather Forecasts (ECMWF) and oceanic …
Low-Frequency Exchange Of Mass Between Ocean Basins, Don P. Chambers, Josh K. Willis
Low-Frequency Exchange Of Mass Between Ocean Basins, Don P. Chambers, Josh K. Willis
Marine Science Faculty Publications
We examine the Gravity Recovery and Climate Experiment (GRACE) data and output from an ocean model to quantify mass fluctuations for the Pacific, Atlantic, and Indian Ocean basins from August 2002 until December 2008. The monthly spatial mean is removed to study interbasin mass exchange. We find a seasonal exchange of mass between the Atlantic and Pacific that is similar to one documented previously, although the amplitude observed by GRACE is about 20% lower than that simulated by an ocean model. There are also significant fluctuations with periods longer than 1 year. We find large interannual exchanges in 2005 and …
Evaluation Of Groundwater Storage Monitoring With The Grace Satellite: Case Study High Plains Aquifer, Central United States, Gil Strassberg, Bridget Scanlon, D. Chambers
Evaluation Of Groundwater Storage Monitoring With The Grace Satellite: Case Study High Plains Aquifer, Central United States, Gil Strassberg, Bridget Scanlon, D. Chambers
Marine Science Faculty Publications
Water scarcity is a critical issue in semiarid regions; however, regional groundwater monitoring is extremely limited. This study evaluates the ability of the GRACE satellites to monitor groundwater storage in the semiarid High Plains aquifer, United States (450,000 km2 area), which is subjected to intense irrigation. GRACE-derived terrestrial water storage (TWS) is highly correlated with the sum of soil moisture (SM) and groundwater storage (GWS) (R = 0.96 for in situ measured SM from 78 stations and R = 0.95 for simulated SM with the Noah land surface model with root-mean-square difference of 38 mm and 36 mm, …
Analysis Of Large-Scale Ocean Bottom Pressure Variability In The North Pacific, Don P. Chambers, Josh K. Willis
Analysis Of Large-Scale Ocean Bottom Pressure Variability In The North Pacific, Don P. Chambers, Josh K. Willis
Marine Science Faculty Publications
[1] We use the leading empirical orthogonal functions (EOFs) of ocean bottom pressure (OBP) derived from an ocean model and the technique of EOF reconstruction to reduce noise in the large-scale OBP variations derived from the Gravity Recovery and Climate Experiment (GRACE). The subsequent OBP variations from the model and GRACE are then examined in the North Pacific between January 2003 and May 2007. Although annual and semiannual variations are similar, GRACE observes large interannual fluctuations poleward of 30°, where OBP increases from a low of nearly 3 cm below normal in early 2003 to normal throughout 2004 and 2005, …
Grace Observes Small-Scale Mass Loss In Greenland, B. Wouters, D. Chambers, E.J. O. Schrama
Grace Observes Small-Scale Mass Loss In Greenland, B. Wouters, D. Chambers, E.J. O. Schrama
Marine Science Faculty Publications
Using satellite gravity data between February 2003 and January 2008, we examine changes in Greenland's mass distribution on a regional scale. During this period, Greenland lost mass at a mean rate of 179 ± 25 Gt/yr, equivalent to a global mean sea level change of 0.5 ± 0.1 mm/yr. Rates increase over time, suggesting an acceleration of the mass loss, driven by mass loss during summer. The largest mass losses occurred along the southeastern and northwestern coast in the summers of 2005 and 2007, when the ice sheet lost 279 Gt and 328 Gt of ice respectively within 2 months. …
Estimating Geocenter Variations From A Combination Of Grace And Ocean Model Output, Sean Swenson, D. Chambers, John Wahr
Estimating Geocenter Variations From A Combination Of Grace And Ocean Model Output, Sean Swenson, D. Chambers, John Wahr
Marine Science Faculty Publications
In this study, we estimate a time series of geocenter anomalies from a combination of data from the Gravity Recovery and Climate Experiment (GRACE) satellite mission and the output from ocean models. A matrix equation is derived relating total geocenter variations to the GRACE coefficients of degrees two and higher and to the oceanic component of the degree one coefficients. We estimate the oceanic component from t wo state-of-the-art ocean models. Results are compared to independent estimates of geocenter derived from other satellite data, such as satellite laser ranging and GPS. Finally, we compute degree one coefficients that are consistent …
Effects Of Ice Melting On Grace Observations Of Ocean Mass Trends, Don P. Chambers, Mark E. Tamisiea, R Steven Nerem, John C. Ries
Effects Of Ice Melting On Grace Observations Of Ocean Mass Trends, Don P. Chambers, Mark E. Tamisiea, R Steven Nerem, John C. Ries
Marine Science Faculty Publications
The Gravity Recovery and Climate Experiment (GRACE) was designed to measure variations in the Earth's gravity field from space at monthly intervals. Researchers have used these data to measure changes in water mass over various regions, including the global oceans and continental ice sheets covering Greenland and Antarctica. However, GRACE data must be smoothed in these analyses and the effects of geocenter motions are not included. In this study, we examine what effect each of these has in the computation of ocean mass trends using a simulation of ice melting on Greenland, Antarctica, and mountain glaciers. We find that the …
Observing Seasonal Steric Sea Level Variations With Grace And Satellite Altimetry, Don P. Chambers
Observing Seasonal Steric Sea Level Variations With Grace And Satellite Altimetry, Don P. Chambers
Marine Science Faculty Publications
Sea level rises and falls as the temperature and salinity of the water column varies, which is known as steric sea level. Sea level also changes as water mass is redistributed within the ocean or is added or removed. Satellite radar altimeters measure the combination of both effects, while the Gravity Recovery and Climate Experiment (GRACE) was designed to measure time variable gravity caused by movement of water mass. Theoretically, altimetry and GRACE data can be combined in order to compute the steric sea level variations. We test this by combining current GRACE and Jason 1 altimeter data and comparing …