Abyssal currents driven by a local wind forcing through deep mixed layer: implication to the east sea

2005 ◽  
Vol 40 (2) ◽  
pp. 101-107 ◽  
Author(s):  
Young Ho Seung
Keyword(s):  
Mixed Layer ◽  
Wind Forcing ◽  
East Sea ◽  
Local Wind ◽  
Deep Mixed Layer ◽  
Abyssal Currents ◽  
Local Wind Forcing

Local wind forcing of the Monterey Bay area inner shelf

2005 ◽  
Vol 25 (3) ◽  
pp. 397-417 ◽  
Author(s):  
Patrick T. Drake ◽  
Margaret A. McManus ◽  
Curt D. Storlazzi
Keyword(s):  
Wind Forcing ◽  
Monterey Bay ◽  
Local Wind ◽  
Inner Shelf ◽  
Bay Area ◽  
Local Wind Forcing

scholarly journals Interannual variability of sea level in the South Indian Ocean: Local versus remote forcing mechanisms

2021 ◽  
Author(s):  
Marion Kersalé ◽  
Denis L. Volkov ◽  
Kandaga Pujiana ◽  
Hong Zhang
Keyword(s):  
Indian Ocean ◽  
Interannual Variability ◽  
Sea Level ◽  
Heat Content ◽  
Wind Forcing ◽  
Local Wind ◽  
South Indian Ocean ◽  
South Indian ◽  
Local Wind Forcing ◽  
And Sea Level

Abstract. The subtropical South Indian Ocean (SIO) has been described as one of the world's largest heat accumulators due to its remarkable warming during the past two decades. However, the relative contributions of the remote (of Pacific origin) forcing and local wind forcing to the variability of heat content and sea level in the SIO have not been fully attributed. Here, we combine a general circulation model, an analytic linear reduced gravity model, and observations to disentangle the spatial and temporal inputs of each forcing component on interannual to decadal timescales. A sensitivity experiment is conducted with artificially closed Indonesian straits to physically isolate the Indian and Pacific Oceans, thus, intentionally removing the Indonesian throughflow (ITF) influence on the Indian Ocean heat content and sea level variability. We show that the relative contribution of the signals originating in the equatorial Pacific versus signals caused by local wind forcing to the interannual variability of sea level and heat content in the SIO is dependent on location within the basin (low vs. mid latitude; western vs. eastern side of the basin). The closure of the ITF in the numerical experiment reduces the amplitude of interannual-to-decadal sea level changes compared to the simulation with a realistic ITF. However, the spatial and temporal evolution of sea level patterns in the two simulations remain similar and correlated with El Nino Southern Oscillation (ENSO). This suggests that these patterns are mostly determined by local wind forcing and oceanic processes, linked to ENSO via the ‘atmospheric bridge’ effect. We conclude that local wind forcing is an important driver for the interannual changes of sea level, heat content, and meridional transports in the SIO subtropical gyre, while oceanic signals originating in the Pacific amplify locally-forced signals.

Dramatic reduction and quick recovery of the South Indian Ocean heat content and sea level in 2014-2019

2020 ◽  
Author(s):  
Denis Volkov ◽  
Michael Rudko ◽  
Sang-Ki Lee
Keyword(s):  
Sea Level ◽  
Rossby Waves ◽  
Heat Content ◽  
Ocean Heat Content ◽  
Wind Forcing ◽  
Upper Ocean ◽  
Local Wind ◽  
Upper Ocean Heat Content ◽  
Local Wind Forcing ◽  
And Sea Level

<p>The interannual-to-decadal variability of heat content and sea level in the South Indian Ocean (SIO) is strongly influenced by its connection with the Pacific and large-scale climatic forcing in the Indo-Pacific region primarily associated with El Niño-Southern Oscillation (ENSO). Besides the advection by the Indonesian Throughflow, signals generated in the Pacific can enter the SIO as coastally trapped Kelvin waves and propagate along the coast of Western Australia. In the southeast tropical and subtropical Indian Ocean, these signals along the eastern boundary can radiate westward as Rossby waves and eventually impact sea level and heat content in the SIO interior and near the western boundary. Local wind forcing, through Ekman pumping over the open ocean and coastal upwelling, is also able to generate Rossby waves and/or modify those emanated from the eastern boundary.</p><p>As measured by Argo floats and satellite altimetry, a decade-long increase of the upper-ocean heat content and sea level in the SIO in 2004-2013 ended with a remarkable drop returning to the initial values in 2004. This basin-wide heat release was associated with one of the strongest on record El Niño events in 2014-2016. Surprisingly, the basin-averaged heat content and sea level quickly recovered during the weak La Niña event in 2017-2019. Here we present an analysis of the evolution and mechanisms of 2014-2016 cooling and subsequent warming in the SIO subtropical gyre. We show that the 2014-2016 El Niño did contribute to the reduced heat content in the eastern SIO, while the local wind forcing (via increased Ekman upwelling) largely contributed to the heat reduction in the western SIO. We find no evidence to support that the 2017-2018 warming was forced by the weak La Niña, because the upper-ocean heat content in eastern SIO was still below normal during 2016-2018. The recovery largely occurred in the western SIO due to local wind forcing (via increased Ekman downwelling) primarily associated with changes in the strength of the southeasterly trade winds.</p><p>Because sea level is a good proxy for the oceanic heat content in the SIO, we extend our analysis back to 1993 using satellite altimetry records. Using a simple model of wind-forced Rossby waves, we estimate the relative contributions of sea level signals propagating from the eastern boundary, the origin of which is strongly linked to ENSO, and the local wind forcing in the SIO interior to the observed sea level variability. The local wind forcing appears to dominate the sea level (and, hence, the upper-ocean heat content) variability in the western SIO, especially in 2013-2019, while the ENSO-related signals are dominant in the eastern SIO. The local wind forcing over the SIO interior effectively suppressed the cooling associated with the most recent 2014-2016 El Niño event. In contrast, the cooling associated with the strongest on record 1997-1998 El Niño was amplified by the local wind forcing in the basin’s interior.</p>

Alongshelf Variability of Inner-Shelf Circulation along the Central Oregon Coast during Summer

2009 ◽  
Vol 39 (6) ◽  
pp. 1380-1398 ◽  
Author(s):  
Anthony R. Kirincich ◽  
John A. Barth
Keyword(s):  
Momentum Equation ◽  
Wind Forcing ◽  
Spatial And Temporal Variability ◽  
Local Wind ◽  
Inner Shelf ◽  
Oregon Coast ◽  
Bottom Stress ◽  
Shelf Circulation ◽  
Invertebrate Species ◽  
Local Wind Forcing

Abstract The spatial and temporal variability of inner-shelf circulation along the central Oregon coast during the 2004 upwelling season is described using a 70-km-long array of moorings along the 15-m isobath. Circulation at three stations located onshore of a submarine bank differed from that of a station north of the bank, despite the relatively uniform wind forcing and inner-shelf bathymetry present. During upwelling-favorable winds, strong southward alongshelf flow occurred north of the bank, no alongshelf flow occurred onshore of the northern part of the bank, and increasing southward flow occurred onshore of the southern part of the bank. During downwelling-favorable winds, strong northward flow occurred in the inner shelf onshore of the bank while weak flow occurred north of the bank. These alongshelf differences in inner-shelf circulation were due to the effects of the bank, which isolated the inner shelf onshore of the bank from the regional upwelling circulation that was evident at the northernmost station. As a result, circulation onshore of the bank was driven primarily by local wind forcing, while flow north of the bank was only partially driven by local winds. A secondary mode of variability, attributed to the movement of the regional upwelling jet due to remote forcings, contributed the bulk of the variability observed north of the bank. With the time-dependent wind forcing present, acceleration was an important term in the depth-averaged alongshelf momentum equation at all stations. During upwelling, bottom stress and acceleration opposed the wind stress north of the bank, while bottom stress was weaker onshore of the bank where the across-shelf momentum flux and the alongshelf pressure gradient balanced the residual of the acceleration and stresses. During downwelling, waters onshore of the bank surged northward at magnitudes much larger than that found north of the bank. These spatial variations developed as the season progressed and the regional upwelling circulation intensified, explaining known variations in growth and recruitment of nearshore invertebrate species.

scholarly journals LOCAL WIND FORCING AND SMALL SCALE UPWELLING

1982 ◽  
Vol 1 (18) ◽  
pp. 144
Author(s):  
Cairns A.R. Bain
Keyword(s):  
Wind Stress ◽  
Coastal Upwelling ◽  
Wind Forcing ◽  
Small Scale ◽  
Local Wind ◽  
Coastal Site ◽  
Sea Temperature ◽  
Stress Effects ◽  
Wind Events ◽  
Local Wind Forcing

This study characterizes some wind stress effects on a coastal site which is a focus of small scale upwelling having a scale of the order of 10 km. Two time scales are considered. Firstly the seasonal character of wind stress with the associated sea temperature fluctuations is described. Secondly individual wind events of a few days duration are characterized by extent and rate of upwelling and offshore displacement of the thermocline front. Data on the thermocline displacement is fitted to Csanady's model of coastal upwelling, which leads to the prediction of upwelling parameters for given wind events.

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