Development of the Flow Field during the Onset of the Somali Current, 1979

Leetmaa, Ants; Quadfasel, Detlef; Wilson, DW

doi:10.1175/1520-0485(1982)012<1325:dotffd>2.0.co;2

Cited by 56 publications

(26 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This damping effect of wind stress curl by vorticity of surface current is weakened in noU e and completely removed in noU tot , resulting in excessive negative wind stress curl there. This coincides with too deep GWs in noU e and noU tot , supporting the dynamical connection between enhanced negative wind stress curl and the amplified GW (Leetmaa et al 1982). In summary, Figs.…”

Section: Effect Of Surface Current-wind Couplingsupporting

confidence: 70%

“…The negative stress curl is particularly enhanced over the eastern edge of the GW and CF. The associated negative vorticity forcing onto the ocean is known to spin up the GW (Leetmaa et al 1982). In contrast, the positive wind stress curl tracks the northern shoulder of the GW, which abuts the southern edge of the CF.…”

Section: The Time-mean Responses In the Wind And Circulation Fields Amentioning

confidence: 99%

“…Many previous studies have examined mechanisms for formation and maintenance of the GW. Some point to local wind curl east of the Findlater (or Somali) Jet (Leetmaa et al 1982;Luther and O'Brien 1989), while others attribute the formation and maintenance to the remote influence of the westwardpropagating Rossby waves (Schott and Quadfasel 1982;Brandt et al 2003;Beal and Donohue 2013). Jensen (1991) suggests that large kinetic energy of the SC and lateral gradient in relative vorticity lead to barotropic instability and formation of the GW.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Distinct Influence of Air–Sea Interactions Mediated by Mesoscale Sea Surface Temperature and Surface Current in the Arabian Sea

Seo

2017

Journal of Climate

View full text Add to dashboard Cite

During the southwest monsoons, the Arabian Sea (AS) develops highly energetic mesoscale variability associated with the Somali Current (SC), Great Whirl (GW), and cold filaments (CF). The resultant highamplitude anomalies and gradients of sea surface temperature (SST) and surface currents modify the wind stress, triggering the so-called mesoscale coupled feedbacks. This study uses a high-resolution regional coupled model with a novel coupling procedure that separates spatial scales of the air-sea coupling to show that SST and surface currents are coupled to the atmosphere at distinct spatial scales, exerting distinct dynamic influences. The effect of mesoscale SST-wind interaction is manifested most strongly in wind work and Ekman pumping over the GW, primarily affecting the position of GW and the separation latitude of the SC. If this effect is suppressed, enhanced wind work and a weakened Ekman pumping dipole cause the GW to extend northeastward, delaying the SC separation by 18. Current-wind interaction, in contrast, is related to the amount of wind energy input. When it is suppressed, especially as a result of background-scale currents, depth-integrated kinetic energy, both the mean and eddy, is significantly enhanced. Ekman pumping velocity over the GW is overly negative because of a lack of vorticity that offsets the wind stress curl, further invigorating the GW. Moreover, significant changes in time-mean SST and evaporation are generated in response to the current-wind interaction, accompanied by a noticeable southward shift in the Findlater Jet. The significant increase in moisture transport in the central AS implies that air-sea interaction mediated by the surface current is a potentially important process for simulation and prediction of the monsoon rainfall.

show abstract

Section: Effect Of Surface Current-wind Couplingsupporting

confidence: 70%

Section: The Time-mean Responses In the Wind And Circulation Fields Amentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Distinct Influence of Air–Sea Interactions Mediated by Mesoscale Sea Surface Temperature and Surface Current in the Arabian Sea

Seo

2017

Journal of Climate

View full text Add to dashboard Cite

show abstract

“…and with profiling current meters along sections normal to the coast between 2øS and 9.5øN [Leetmaa et al, 1982] showed the existence of a narrow southward undercurrent off the east African coast between --•4øN and the northernmost latitude of observations. Near 9øN the undercurrent was observed in the depth range 150-600 m, and the core of the undercurrent was observed to rise on its way south.…”

Section: During the Fgge Indian Ocean Experiments (Index) From March Tmentioning

confidence: 93%

“…The above-described surface flow pattern for the onset and evolution of the summer monsoon is pieced together from the INDEX '79 observations [Leetmaa et al, 1982;Schott and Quadfasel, 1982;Swallow et al, 1983] pattern after step 6 in the transition period after the summer monsoon and during the onset of the winter monsoon. During the winter monsoon a southward subsurface flow will obviously be part of the surface circulation, and during various other phases it will be an undercurrent.…”

Section: Then the 'Two-wedge' Situation Collapses The Southern Wedgementioning

confidence: 99%

Southward subsurface flow below the Somali Current

Quadfasel¹,

Schott²

1983

J. Geophys. Res.

View full text Add to dashboard Cite

The existence of a southward‐flowing current beneath the northern part of the seasonally reversing Somali Current is documented in a 2½‐year‐long time series of currents obtained at moored stations near 5°N about 30 km off the Somali coast. Its mean annual transport in the layer 150–600 m amounts to about 5×106 m3/s. The undercurrent has a pronounced seasonal cycle in phase with the near surface flow, suggesting a close coupling to the monsoonal wind forcing. With the spin‐up of the deepreaching northern Somali gyre after the onset of the southwest monsoon, the undercurrent is temporarily destroyed in the northern Somali Basin during June/July but is re‐established in August. The undercurrent does not reach 3°N but turns offshore north of that latitude.

show abstract

Mesoscale dynamics in the Arabian Sea and a focus on the Great Whirl life cycle: A numerical investigation using ROMS

et al. 2014

View full text Add to dashboard Cite

The Great Whirl (GW) is a persistent anticyclonic mesoscale eddy that is observed seasonally in the Arabian Sea during a period embedding the 3 months of the southwest monsoon (June-July-August) at a quasi-steady location. Its dynamics remain unclear despite it being one of the largest coherent vortices in the world ocean. Realistic regional numerical experiments using ROMS are performed to investigate the life cycle of the GW, which is not well resolved by sparse available in situ measurements in the region. Using a set of sensitivity experiments and an accurate temporal characterization of the eddy properties (including position, radius, depth, and vorticity) we (i) confirm the role of basin-scale downwelling Rossby waves in the GW generation, (ii) clarify the role of the monsoonal strong anticyclonic wind in its maintenance and barotropization, and (iii) suggest a connection between basin-scale Rossby wave dynamics and GW collapse.

show abstract

Development of the Flow Field during the Onset of the Somali Current, 1979

Cited by 56 publications

References 0 publications

Distinct Influence of Air–Sea Interactions Mediated by Mesoscale Sea Surface Temperature and Surface Current in the Arabian Sea

Distinct Influence of Air–Sea Interactions Mediated by Mesoscale Sea Surface Temperature and Surface Current in the Arabian Sea

Southward subsurface flow below the Somali Current

Mesoscale dynamics in the Arabian Sea and a focus on the Great Whirl life cycle: A numerical investigation using ROMS

Contact Info

Product

Resources

About