scholarly journals A Global Evaluation of Ocean Bottom Pressure from GRACE, OMCT, and Steric-Corrected Altimetry

2010 ◽  
Vol 27 (8) ◽  
pp. 1395-1402 ◽  
Author(s):  
Don P. Chambers ◽  
Josh K. Willis
Keyword(s):  
Ocean Model ◽  
Empirical Orthogonal Functions ◽  
Global Evaluation ◽  
Ocean Bottom ◽  
Bottom Pressure ◽  
Orthogonal Functions ◽  
Ocean Bottom Pressure ◽  
Grace Data ◽  
Point To Point ◽  
Gaussian Maps

Abstract Ocean bottom pressure (OBP) from the Gravity Recovery and Climate Experiment (GRACE) and the Ocean Model for Circulation and Tides (OMCT) are compared globally with OBP computed from altimetry corrected for steric variations from Argo floats from January 2005 to December 2007. Two methods of smoothing the GRACE data are examined. The first uses a standard Gaussian smoother with a radius of 300 km. The second method projects those smoothed maps onto empirical orthogonal functions derived from OMCT in a least squares estimation in order to produce maps that better agree with the physical processes embodied by the model. These new maps agree significantly better with estimates from the steric-corrected altimetry, reducing the variance on average by 30% over 70% of the ocean. This is compared to smaller reductions over only 14% of the ocean using the 300-km Gaussian maps and 56% of the ocean using OMCT maps. The OMCT maps do not reduce variance as much in the Southern Ocean where OBP variations are largest, whereas the GRACE maps do. Based on this analysis, it is estimated that the local, or point-to-point, uncertainty of new EOF filtered maps of GRACE OBP is 1.3 (one standard deviation).

scholarly journals ENSO-correlated fluctuations in ocean bottom pressure and wind-stress curl in the North Pacific

Ocean Science ◽  
2011 ◽  
Vol 7 (5) ◽  
pp. 685-692 ◽  
Author(s):  
D. P. Chambers
Keyword(s):  
Wind Stress ◽  
North Pacific ◽  
Low Frequency ◽  
Ocean Model ◽  
Ocean Bottom ◽  
Bottom Pressure ◽  
Wind Stress Curl ◽  
Ocean Bottom Pressure ◽  
The North ◽  
The North Pacific

Abstract. We examine the output of an ocean model forced by ECMWF winds to study the theoretical relationship between wind-induced changes in ocean bottom pressure in the North Pacific between 1992 until 2010 and ENSO. Our analysis indicates that while there are significant fluctuations correlated with some El Niño and La Niña events, the correlation is still relatively low. Moreover, the ENSO-correlated variability explains only 50 % of the non-seasonal, low-frequency variance. There are significant residual fluctuations in both wind-stress curl and ocean bottom pressure in the region with periods of 4-years and longer. One such fluctuation began in late 2002 and has been observed by the Gravity Recovery and Climate Experiment (GRACE). Even after accounting for possible ENSO-correlated variations, there is a significant trend in ocean bottom pressure in the region, equivalent to 0.7 ± 0.3 cm yr−1 of sea level from January 2003 until December 2008, which is confirmed with steric-corrected altimetry. Although this low-frequency fluctuation does not appear in the ocean model, we show that ECMWF winds have a significantly reduced trend that is inconsistent with satellite observations over the same time period, and so it appears that the difference is due to a forcing error in the model and not an intrinsic error.

scholarly journals On the seasonal variations of ocean bottom pressure in the world oceans

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Xuhua Cheng ◽  
Niansen Ou ◽  
Jiajia Chen ◽  
Rui Xin Huang
Keyword(s):  
Seasonal Variations ◽  
Ocean Model ◽  
Wind Forcing ◽  
Ekman Transport ◽  
Boreal Winter ◽  
Freshwater Flux ◽  
Ocean Bottom ◽  
Bottom Pressure ◽  
Ocean Bottom Pressure ◽  
The World

AbstractSeasonal variability of the ocean bottom pressure (OBP) in the world oceans is investigated using 15 years of GRACE observations and a Pressure Coordinate Ocean Model (PCOM). In boreal winter, negative OBP anomalies appear in the northern North Pacific, subtropical South Pacific and north of 40 °S in the Indian Ocean, while OBP anomaly in the Southern Ocean is positive. The summer pattern is opposite to that in winter. The centers of positive (negative) OBP signals have a good coherence with the mass convergence/divergence due to Ekman transport, indicating the importance of wind forcing. The PCOM model reproduces the observed OBP quite well. Sensitivity experiments indicate that wind forcing dominates the regional OBP seasonal variations, while the contributions due to heat flux and freshwater flux are unimportant. Experiments with daily sea level pressure (SLP) forcing suggest that at high frequencies the non-static effect of SLP is not negligible.

scholarly journals Spatio-Temporal Patterns of Mass Changes in Himalayan Glaciated Region from EOF Analyses of GRACE Data

2021 ◽  
Vol 13 (2) ◽  
pp. 265
Author(s):  
Harika Munagapati ◽  
Virendra M. Tiwari
Keyword(s):  
Temperature Anomaly ◽  
Mass Gain ◽  
Snow Accumulation ◽  
Empirical Orthogonal Functions ◽  
Total Water ◽  
Orthogonal Functions ◽  
Grace Data ◽  
Grace Satellite ◽  
Spatio Temporal ◽  
Gravity Recovery

The nature of hydrological seasonality over the Himalayan Glaciated Region (HGR) is complex due to varied precipitation patterns. The present study attempts to exemplify the spatio-temporal variation of hydrological mass over the HGR using time-variable gravity from the Gravity Recovery and Climate Experiment (GRACE) satellite for the period of 2002–2016 on seasonal and interannual timescales. The mass signal derived from GRACE data is decomposed using empirical orthogonal functions (EOFs), allowing us to identify the three broad divisions of HGR, i.e., western, central, and eastern, based on the seasonal mass gain or loss that corresponds to prevailing climatic changes. Further, causative relationships between climatic variables and the EOF decomposed signals are explored using the Granger causality algorithm. It appears that a causal relationship exists between total precipitation and total water storage from GRACE. EOF modes also indicate certain regional anomalies such as the Karakoram mass gain, which represents ongoing snow accumulation. Our causality result suggests that the excessive snowfall in 2005–2008 has initiated this mass gain. However, as our results indicate, despite the dampening of snowfall rates after 2008, mass has been steadily increasing in the Karakorum, which is attributed to the flattening of the temperature anomaly curve and subsequent lower melting after 2008.

scholarly journals Analysis of Ocean Bottom Pressure Anomalies and Seismic Activities in the MedRidge Zone

2021 ◽  
Vol 13 (7) ◽  
pp. 1242
Author(s):  
Hakan S. Kutoglu ◽  
Kazimierz Becek
Keyword(s):  
Time Series ◽  
Mass Change ◽  
Ocean Bottom ◽  
Bottom Pressure ◽  
Vertical Movements ◽  
Ocean Bottom Pressure ◽  
Continuous Mass ◽  
Mediterranean Ridge Accretionary Complex ◽  
Gravity Recovery ◽  
Periodic Components

The Mediterranean Ridge accretionary complex (MAC) is a product of the convergence of Africa–Europe–Aegean plates. As a result, the region exhibits a continuous mass change (horizontal/vertical movements) that generates earthquakes. Over the last 50 years, approximately 430 earthquakes with M ≥ 5, including 36 M ≥ 6 earthquakes, have been recorded in the region. This study aims to link the ocean bottom deformations manifested through ocean bottom pressure variations with the earthquakes’ time series. To this end, we investigated the time series of the ocean bottom pressure (OBP) anomalies derived from the Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow-On (GRACE-FO) satellite missions. The OBP time series comprises a decreasing trend in addition to 1.02, 1.52, 4.27, and 10.66-year periodic components, which can be explained by atmosphere, oceans, and hydrosphere (AOH) processes, the Earth’s pole movement, solar activity, and core–mantle coupling. It can be inferred from the results that the OBP anomalies time series/mass change is linked to a rising trend and periods in the earthquakes’ energy time series. Based on this preliminary work, ocean-bottom pressure variation appears to be a promising lead for further research.

Near-field tsunami forecasting from cabled ocean bottom pressure data

2009 ◽  
Vol 114 (B6) ◽  
Author(s):  
Hiroaki Tsushima ◽  
Ryota Hino ◽  
Hiromi Fujimoto ◽  
Yuichiro Tanioka ◽  
Fumihiko Imamura
Keyword(s):  
Near Field ◽  
Ocean Bottom ◽  
Bottom Pressure ◽  
Pressure Data ◽  
Ocean Bottom Pressure ◽  
Tsunami Forecasting

scholarly journals Seafloor Crustal Deformation on Ocean Bottom Pressure Records With Nontidal Variability Corrections: Application to Hikurangi Margin, New Zealand

2019 ◽  
Vol 46 (1) ◽  
pp. 303-310 ◽  
Author(s):  
Tomoya Muramoto ◽  
Yoshihiro Ito ◽  
Daisuke Inazu ◽  
Laura M. Wallace ◽  
Ryota Hino ◽  
...  
Keyword(s):  
New Zealand ◽  
Crustal Deformation ◽  
Ocean Bottom ◽  
Bottom Pressure ◽  
Ocean Bottom Pressure
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