Simulation of the Tropical Thermal Domes in the Atlantic: A Seasonal Cycle

Yamagata, Toshio; Iizuka, Satoshi

doi:10.1175/1520-0485(1995)025<2129:sotttd>2.0.co;2

Cited by 46 publications

(36 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Considered from a basin-scale perspective, this system forces a cyclonic gyre circulation, the Guinea Gyre [e.g., 6], of which the Guinea Dome and the coastal West-African upwellings form the most eastern features [4,7]. In this paper, we limit our study to the eastern part of the system, bounded in latitude by the Tropic of Cancer and the North Equatorial Counter-Current and in longitude by the Cape Verde Archipelago (CVA around 26 • W) and African coasts.…”

Section: Introductionmentioning

confidence: 99%

“…(adapted from [16]) low hydrostatic pressure. It is centered in the southeast of the archipelago of Cape Verde, and intensifies in summer, at about 12 • N, and 22-23 • W. It is generated by upward Ekman pumping forced by the trade winds convergence [7,17], and belongs to the Guinea Gyre, formed by the NEC and NECC in surface [4,13]. It exist a link between the GD with the Atlantic Meridional Mode (AMM) which is related to the meridional migration of the Intertropical Convergence Zone (ITCZ) [18,19].…”

Section: Introductionmentioning

confidence: 99%

“…The second may suggest that they do not drive the seasonal cycle. More specifically, the upper heat content at ∼12 • N and few specific longitudes, within the Guinea Dome in particular, was studied by Yamagata and Iizuka [7]. They found that the summer subsurface cooling is explained comparably by horizontal and vertical advection.…”

Section: Introductionmentioning

confidence: 99%

“…

…”

mentioning

confidence: 99%

See 3 more Smart Citations

A model study of the seasonality of sea surface temperature and circulation in the Atlantic North-eastern Tropical Upwelling System

et al. 2015

View full text Add to dashboard Cite

The climatological seasonal cycle of the sea surface temperature (SST) in the north-eastern tropical Atlantic (7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25) • N, 26-12 • W) is studied using a mixed layer heat budget in a regional ocean general circulation model. The region, which experiences one of the larger SST cycle in the tropics, forms the main part of the Guinea Gyre. It is characterized by a seasonally varying open ocean and coastal upwelling system, driven by the movements of the intertropical convergence zone (ITCZ). The model annual mean heat budget has two regimes schematically. South of roughly 12 • N, advection of equatorial waters, mostly warm, and warming by vertical mixing, is balanced by net air-sea flux. In the rest of the domain, a cooling by vertical mixing, reinforced by advection at the coast, is balanced by the air-sea fluxes. Regarding the seasonal cycle, within a narrow continental band, in zonal mean, the SST early decrease (from September, depending on latitude, until December) is driven by upwelling dynamics off Senegal and Mauritania (15-20 • N), and instead by air-sea fluxes north and south of these latitudes. Paradoxically, the later peaks of upwelling intensity (from March to July, with increasing latitude) essentially damp the warming phase, driven by air-sea fluxes. The open ocean cycle to the west, is entirely driven by the seasonal net air-sea fluxes. The oceanic processes significantly oppose it, but for winter north of ∼18 • N. Vertical mixing in summer-autumn tends to cool (warm) the surface north (south) of the ITCZ, and advective cooling or warming by the geostrophic Guinea Gyre currents and the Ekman drift. This analysis supports previous findings on the importance of air-sea fluxes offshore. It mainly offers quantitative elements on the modulation of the SST seasonal cycle by the ocean circulation, and particularly by the upwelling dynamics.

show abstract

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…

…”

mentioning

confidence: 99%

See 2 more Smart Citations

A model study of the seasonality of sea surface temperature and circulation in the Atlantic North-eastern Tropical Upwelling System

et al. 2015

View full text Add to dashboard Cite

show abstract

“…Wind driven upwelling over the shelf is seasonally modulated in the latitudes 31-34°S, and strongest in austral summer: October to March (Nelson and Hutchings, 1983;Shannon, 1985;Shannon and Nelson, 1996). The Benguela upwelling zone is exposed to coastal trapped low pressure cells (Jury and Brundrit, 1992;Yamagata and Iizuka, 1995) that amplify the effects of frequent wind reversals. The upwelling intensifies next to capes (Jury, 1988) where alongshore winds and currents accelerate.…”

Section: Introductionmentioning

confidence: 99%

Representation of Coastal Upwelling and Environmental Interactions in the Southern Benguela in Satellite Era Reanalysis

Jury

2013

ijms

View full text Add to dashboard Cite

The ability of ocean and atmosphere reanalysis products to represent coastal upwelling in the southern Benguela (28-36°S, 14-20°E) is studied in the period 1980-2008. Mean maps, depth sections and seasonal cycle are analyzed for ocean color, sea surface temperature (SST), vertical velocity, winds and ocean currents in the zone. The paper first evaluates coastal winds and cross-shelf gradients of temperature in a variety of products; then provides an analysis of inter-relationships among variables averaged in the St Helena Bay sub-area. The 30km Coupled Forecast System reanalysis resolves the cool strip of SST with a 1-2℃ warm bias, while subsurface zonal overturning and a longshore current jet are featured in the 50 km Simple Ocean Data Assimilation reanalysis. Mean coastal upwelling rates of 1-2 m/day are consistent with observations. The expected links are found between the annual cycle of meridional wind stress and longshore currents, and between uplift, temperature and salinity. A new finding is a connection between the zonal wind stress and chlorophyll anomalies (-35.86 mg m -3 /N m -2 ). When the subtropical anticyclone is located southwest of Arica, offshore winds prevail and phytoplankton blooms in the southern Benguela.

show abstract

Intraseasonal variability of tropical Atlantic sea‐surface temperature: air–sea interaction over upwelling fronts

Diakhaté¹,

Coëtlogon

Lazar

et al. 2015

Quart J Royal Meteoro Soc

View full text Add to dashboard Cite

International audienceTropical Atlantic Sea Surface Temperatures (SSTs) maximum Intra-Seasonal Variability (ISV) and their interaction with local surface winds are investigated applying statistical analysis to observations and to a recent coupled reanalysis over the 2000–2009 decade. Five cores of strong ISV emerge, with standard deviation reaching about 1°C in frontal areas of the three main upwelling systems: equatorial, Angola-Benguela and Senegal-Mauritania (the southern side of the Canary upwelling). West of 10°W along the equator, a 20-60-day peak caused by tropical instability waves is shown to generate surface wind anomalies through the adjustment of the horizontal surface pressure gradient in addition to the modification of near-surface atmospheric stratification. East of 10°W along the equator, an intense biweekly oscillation increases the ocean and atmosphere ISV. In the two coastal upwelling fronts, intraseasonal SST anomalies resemble each other. They are shown to be influenced by coastal Kelvin waves in addition to large-scale wind forcing. Over the Angola-Benguela upwelling, coastal wind bursts controlling the SST ISV are associated with anomalously strong pressure patterns related to the Madden-Julian Oscillation, the St. Helena anticyclone, and the Antarctic Oscillation. In the Senegal-Mauritania upwelling, the wind anomalies mainly linked to the Azores anticyclone in the southern front during November to May appear to be connected to the Saharan heat low in the northern front from June to September. In all five regions and as expected for such upwelling regimes, vertical oceanic mixing represents the dominant term in the mixed-layer heat budget. In the equatorial band, as found in previous studies, horizontal advection is equally important, while it appears surprisingly weak in coastal fronts. Finally, a striking result is the general lack of surface wind signal related to the SST ISV in the coastal upwellings

show abstract

Simulation of the Tropical Thermal Domes in the Atlantic: A Seasonal Cycle

Cited by 46 publications

References 0 publications

A model study of the seasonality of sea surface temperature and circulation in the Atlantic North-eastern Tropical Upwelling System

A model study of the seasonality of sea surface temperature and circulation in the Atlantic North-eastern Tropical Upwelling System

Representation of Coastal Upwelling and Environmental Interactions in the Southern Benguela in Satellite Era Reanalysis

Intraseasonal variability of tropical Atlantic sea‐surface temperature: air–sea interaction over upwelling fronts

Contact Info

Product

Resources

About