Estimation of the Atlantic sea-level response to atmospheric pressure using ERS-2 altimeter data and a global ocean model

2002 ◽  
Author(s):  
Jesus Gomez-Enri ◽  
Pilar Villares ◽  
Miguel Bruno ◽  
Jerome Benveniste
Keyword(s):  
Sea Level ◽  
Atmospheric Pressure ◽  
Ocean Model ◽  
Global Ocean ◽  
Altimeter Data

scholarly journals El Niño Effects and Upwelling off South Australia

2007 ◽  
Vol 37 (10) ◽  
pp. 2458-2477 ◽  
Author(s):  
John F. Middleton ◽  
Craig Arthur ◽  
Paul Van Ruth ◽  
Tim M. Ward ◽  
Julie L. McClean ◽  
...  
Keyword(s):  
Sea Level ◽  
Wind Stress ◽  
El Niño ◽  
El Nino ◽  
South Australia ◽  
Ocean Model ◽  
Global Ocean ◽  
Shelf Edge ◽  
The West ◽  
Enso Events

Abstract To determine the possible importance of ENSO events along the coast of South Australia, an exploratory analysis is made of meteorological and oceanographic data and output from a global ocean model. Long time series of coastal sea level and wind stress are used to show that while upwelling favorable winds have been more persistent since 1982, ENSO events (i) are largely driven by signals from the west Pacific Ocean shelf/slope waveguide and not local meteorological conditions, (ii) can account for 10-cm changes in sea level, and (iii) together with wind stress, explain 62% of the variance of annual-averaged sea level. Thus, both local winds and remote forcing from the west Pacific are likely important to the low-frequency shelf edge circulation. Evidence also suggests that, since 1983, wintertime downwelling during the onset of an El Niño is reduced and the following summertime upwelling is enhanced. In situ data show that during the 1998 and 2003 El Niño events anomalously cold (10.5°–11.5°C) water is found at depths of 60–120 m and is more than two standard deviations cooler than the mean. A regression showed that averaged sea level can provide a statistically significant proxy for these subsurface temperature changes and indicates a 2.2°C decrease in temperature for the 10-cm decrease in sea level that was driven by the 1998 El Niño event. Limited current- meter observations, long sea level records, and output from a global ocean model were also examined and provide support for the hypothesis that El Niño events substantially reduce wintertime (but not summertime) shelf-edge currents. Further research to confirm this asymmetric response and its cause is required.

scholarly journals A Global Ocean Observing System for Measuring Sea Level Atmospheric Pressure: Effects and Impacts on Numerical Weather Prediction

2017 ◽  
Vol 98 (2) ◽  
pp. 231-238 ◽  
Author(s):  
Luca Centurioni ◽  
András Horányi ◽  
Carla Cardinali ◽  
Etienne Charpentier ◽  
Rick Lumpkin
Keyword(s):  
Sea Level ◽  
Surface Pressure ◽  
Numerical Weather Prediction ◽  
Atmospheric Pressure ◽  
Weather Prediction ◽  
Global Ocean ◽  
Numerical Weather ◽  
Observation Impact ◽  
The Impact

Abstract Since 1994 the U.S. Global Drifter Program (GDP) and its international partners cooperating within the Data Buoy Cooperation Panel (DBCP) of the World Meteorological Organization (WMO) and the United Nations Education, Scientific and Cultural Organization (UNESCO) have been deploying drifters equipped with barometers primarily in the extratropical regions of the world’s oceans in support of operational weather forecasting. To date, the impact of the drifter data isolated from other sources has never been studied. This essay quantifies and discusses the effect and the impact of in situ sea level atmospheric pressure (SLP) data from the global drifter array on numerical weather prediction using observing system experiments and forecast sensitivity observation impact studies. The in situ drifter SLP observations are extremely valuable for anchoring the global surface pressure field and significantly contributing to accurate marine weather forecasts, especially in regions where no other in situ observations are available, for example, the Southern Ocean. Furthermore, the forecast sensitivity observation impact analysis indicates that the SLP drifter data are the most valuable per-observation contributor of the Global Observing System (GOS). All these results give evidence that surface pressure observations of drifting buoys are essential ingredients of the GOS and that their quantity, quality, and distribution should be preserved as much as possible in order to avoid any analysis and forecast degradations. The barometer upgrade program offered by the GDP, under which GDP-funded drifters can be equipped with partner-funded accurate air pressure sensors, is a practical example of how the DBCP collaboration is executed. Interested parties are encouraged to contact the GDP to discuss upgrade opportunities.

scholarly journals Data assimilation in a reduced gravity ocean model using ERS-l scatterometer and TOPEX altimeter data

MAUSAM ◽  
2021 ◽  
Vol 48 (4) ◽  
pp. 669-678
Author(s):  
RAJ KUMAR ◽  
SUJIT BASU ◽  
B. S. GOHIL ◽  
P. C. PANDEY
Keyword(s):  
Sea Level ◽  
Wind Stress ◽  
Western Indian Ocean ◽  
Ocean Model ◽  
Wind Forcing ◽  
Altimeter Data ◽  
Reduced Gravity ◽  
The North ◽  
Model Equations ◽  
Adjoint Approach

 This paper discusses import of ERS-1 scatterometer winds and assimilation of sea level variability data derived from TOPEX altimeter on the ocean model using adjoint approach. The model developed for the purpose is linear reduced gravity model for the north-western Indian ocean. Experiments have been done with forcing provided using ERS-l satellite scatterometer and analysed wind forcing provided by Florida State University (FSU). Impact on the model has been studied using the analysed wind stress as well as with ERS-l scatterometer-derived wind stress fields. The cost function has been defined as difference between the model derived sea level and altimeter observations. This misfit between model and observations has been minimised with the model equations as constraints. Assimilation has been done for 30 days using scatterometer wind forcing. It has been observed that assimilated sea level with scatterometer-derived wind forcing gives much better results in comparison to unassimilated sea level.    

Satellite Altimeter Data Assimilation in the Occam Global Ocean Model

1999 ◽  
pp. 365-369
Author(s):  
Alan D. Fox ◽  
Keith Haines ◽  
Beverly A. de Cuevas ◽  
Andrew C. Coward
Keyword(s):  
Data Assimilation ◽  
Ocean Model ◽  
Global Ocean ◽  
Altimeter Data ◽  
Satellite Altimeter ◽  
Satellite Altimeter Data

scholarly journals The Global Ocean Mass Budget in 1993–2003 Estimated from Sea Level Change

2007 ◽  
Vol 37 (2) ◽  
pp. 203-213 ◽  
Author(s):  
Manfred Wenzel ◽  
Jens Schröter
Keyword(s):  
Atlantic Ocean ◽  
Sea Level ◽  
Ocean Circulation ◽  
General Circulation ◽  
Circulation Model ◽  
Ocean Model ◽  
Global Ocean ◽  
Mass Budget ◽  
Ocean Mass ◽  
The Pacific

Abstract The mass budget of the ocean in the period 1993–2003 is studied with a general circulation model. The model has a free surface and conserves mass rather than volume; that is, freshwater is exchanged with the atmosphere via precipitation and evaporation and inflow from land is taken into account. The mass is redistributed by the ocean circulation. Furthermore, the ocean’s volume changes by steric expansion with changing temperature and salinity. To estimate the mass changes, the ocean model is constrained by sea level measurements from the Ocean Topography Experiment (TOPEX)/Poseidon mission as well as by hydrographic data. The modeled ocean mass change within the years 2002–03 compares favorably to measurements from the Gravity Recovery and Climate Experiment (GRACE), and the evolution of the global mean sea level for the period 1993–2003 with annual and interannual variations can be reproduced to a 0.15-cm rms difference. Its trend has been measured as 3.37 mm yr−1 while the constrained model gives 3.34 mm yr−1 considering only the area covered by measurements (3.25 mm yr−1 for the total ocean). A steric rise of 2.50 mm yr−1 is estimated in this period, as is a gain in the ocean mass that is equivalent to an eustatic rise of 0.74 mm yr−1. The amplitude and phase (day of maximum value since 1 January) of the superimposed eustatic annual cycle are also estimated to be 4.6 mm and 278°, respectively. The corresponding values for the semiannual cycle are 0.42 mm and 120°. The trends in the eustatic sea level are not equally distributed. In the Atlantic Ocean (80°S–67°N) the eustatic sea level rises by 1.8 mm yr−1 and in the Indian Ocean (80°S–30°N) it rises by 1.4 mm yr−1, but it falls by −0.20 mm yr−1 in the Pacific Ocean (80°S–67°N). The latter is mainly caused by a loss of mass through transport divergence in the Pacific sector of the Antarctic Circumpolar Current (−0.42 Sv; Sv ≡ 109 kg s−1) that is not balanced by the net surface water supply. The consequence of this uneven eustatic rise is a shift of the oceanic center of mass toward the Atlantic Ocean and to the north.

Correction of TOPEX/POSEIDON altimeter data for nonisostatic sea level response to atmospheric pressure in the Japan/East Sea

2004 ◽  
Vol 31 (2) ◽  
Author(s):  
Sung Hyun Nam ◽  
Sang Jin Lyu ◽  
Young Ho Kim ◽  
Kuh Kim ◽  
Jae-Hun Park ◽  
...  
Keyword(s):  
Sea Level ◽  
Atmospheric Pressure ◽  
East Sea ◽  
Altimeter Data

scholarly journals Formulation of a new explicit tidal scheme in ocean general circulation model

2022 ◽  
Author(s):  
Jiangbo Jin ◽  
Run Guo ◽  
Minghua Zhang ◽  
Guangqing Zhou ◽  
Qingcun Zeng
Keyword(s):  
Sea Level ◽  
General Circulation ◽  
Thermohaline Circulation ◽  
Circulation Model ◽  
Ocean General Circulation Model ◽  
Ocean Model ◽  
Tidal Mixing ◽  
Global Ocean ◽  
The North ◽  
Tidal Constituents

Abstract. Tides play an important role in ocean energy transfer and mixing, and provide major energy for maintaining thermohaline circulation. This study proposes a new explicit tidal scheme and assesses its performance in a global ocean model. Instead of using empirical specifications of tidal amplitudes and frequencies, the new scheme directly uses the positions of the Moon and Sun in a global ocean model to incorporate tides. Compared with the traditional method that has specified tidal constituents, the new scheme can better simulate the diurnal and spatial characteristics of the tidal potential of spring and neap tides as well as the spatial patterns and magnitudes of major tidal constituents (K1 and M2). It significantly reduces the total errors of eight tidal constituents (with the exception of N2 and Q1) in the traditional explicit tidal scheme. Relative to the control simulation without tides, both the new and traditional tidal schemes can lead to better dynamic sea level (DSL) simulation in the North Atlantic, reducing significant negative biases in this region. The new tidal scheme also shows smaller positive bias than the traditional scheme in the Southern Ocean. The new scheme is suited to calculate regional distributions of sea level height in addition to tidal mixing.

scholarly journals Impact of model resolution on sea-level variability characteristics at various space and time scales: insights from four DRAKKAR global simulations and the AVISO altimeter data

2009 ◽  
Vol 6 (2) ◽  
pp. 1513-1545 ◽  
Author(s):  
T. Penduff ◽  
M. Juza ◽  
L. Brodeau ◽  
G. C. Smith ◽  
B. Barnier ◽  
...  
Keyword(s):  
Sea Level ◽  
Large Scale ◽  
Coupled Processes ◽  
Global Ocean ◽  
Altimeter Data ◽  
Spatial Correlations ◽  
Temporal Correlations ◽  
Sea Level Anomalies ◽  
Day Range ◽  
Standard Deviations

Abstract. Four global ocean/sea-ice simulations driven by the same realistic 46-year daily atmospheric forcing were performed within the DRAKKAR project at 2°, 1°, ½° and ¼° resolutions. Model sea-level anomalies are collocated over the period 1993–2004 onto the AVISO SLA dataset. These five collocated SLA datasets are then filtered and quantitatively compared over various time and space scales regarding three characteristics: SLA standard deviations, spatial correlations between SLA variability maps, and temporal correlations between observed and simulated band-passed filtered local SLA timeseries. Beyond the 2°–1° transition whose benefits are quite moderate, further increases in resolution and associated changes in subgrid scale parameterizations simultaneously induce (i) strong increases in SLA standard deviations, (ii) strong improvements in the spatial distribution of SLA variability, and (iii) slight decreases in temporal correlations between observed and simulation SLA timeseries. These 3 effects are not only clear on mesoscale (14–180 days) and quasi-annual (5–18 months) fluctuations, but also on the slower (interannual), large-scale variability ultimately involved in ocean-atmosphere coupled processes. Most SLA characteristics are monotonically affected by successive resolution increases, but irregularly and with a strong dependance on frequency and latitude. Benefits of enhanced resolution are maximum in the ½°–¼° transition, in the 14–180 day range, and within eddy-active mid- and high-latitude regions. They are particularly clear in the Southern Ocean where mesoscale eddies probably sustain a substantial intrinsic interannual variability.

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