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

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.

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

Journal of Atmospheric and Oceanic Technology ◽

10.1175/2010jtecho738.1 ◽

2010 ◽

Vol 27 (8) ◽

pp. 1395-1402 ◽

Cited By ~ 31

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).

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A global barotropic ocean model driven by synoptic atmospheric disturbances for detecting seafloor vertical displacements from in situ ocean bottom pressure measurements

Marine Geophysical Research ◽

10.1007/s11001-012-9151-7 ◽

2012 ◽

Vol 33 (2) ◽

pp. 127-148 ◽

Cited By ~ 9

Author(s):

Daisuke Inazu ◽

Ryota Hino ◽

Hiromi Fujimoto

Keyword(s):

Ocean Model ◽

Ocean Bottom ◽

Pressure Measurements ◽

Bottom Pressure ◽

Ocean Bottom Pressure ◽

Model Driven ◽

Atmospheric Disturbances ◽

Vertical Displacements

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

Ocean Science ◽

10.5194/os-7-685-2011 ◽

2011 ◽

Vol 7 (5) ◽

pp. 685-692 ◽

Cited By ~ 15

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.

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Mechanism of Interannual Variability of Ocean Bottom Pressure in the South Pacific

10.21203/rs.3.rs-559761/v1 ◽

2021 ◽

Author(s):

Jianhuang Qin ◽

Xuhua Cheng ◽

Chengcheng Yang ◽

Niansen Ou ◽

Xiaoqin Xiong

Keyword(s):

Sea Level ◽

Southern Oscillation ◽

South Pacific ◽

Ekman Transport ◽

Ocean Bottom ◽

Bottom Pressure ◽

The South ◽

Austral Spring ◽

Ocean Bottom Pressure ◽

Southeastern Pacific

Abstract The study of ocean bottom pressure (OBP) is useful for understanding the barotropic processes variability that contribute to sea level rise. Previous studies have reported the strong OBP anomalies in the Southern Ocean on different time scales. In this study, the characteristic and mechanisms of the energetic interannual OBP variability in the southeastern Pacific are examined using 14 years of GRACE data. It is found that the OBP anomalies are positive (negative) related to the convergence (divergence) of Ekman transport forced by local winds variability. The sea level pressure (SLP) anomalies shows a wavenumber-3 structure in the high latitude of the South Pacific, which benefits a strong and persistent anticyclone over the southeastern Pacific, leading to the positive OBP anomalies there. Such SLP anomalies are similar to the second Pacific-South American (PSA2). Moreover, El Niño–Southern Oscillation (ENSO) plays an important role in the austral spring (August-November) OBP variability and leads the austral autumn (March-June) OBP variability by 1 season. These results highlight the influence of atmospheric variability on OBP anomalies and are validated by a mass conservation (non-Boussinesq) ocean model, which is expected to not only better understanding of OBP mechanisms in a longer time, but also predict OBP variation in the global scale.

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

Remote Sensing ◽

10.3390/rs13071242 ◽

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.

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