scholarly journals A ‘self-adjustment’ mechanism for mixed-layer heat budget in the equatorial Atlantic cold tongue

2017 ◽  
Vol 18 (2) ◽  
pp. 82-87 ◽  
Author(s):  
Yanyan Shi ◽  
Bin Wang ◽  
Wenyu Huang
Keyword(s):  
Mixed Layer ◽  
Heat Budget ◽  
Cold Tongue ◽  
Equatorial Atlantic ◽  
Adjustment Mechanism ◽  
Mixed Layer Heat Budget ◽  
Atlantic Cold Tongue

scholarly journals Diapycnal heat flux and mixed layer heat budget within the Atlantic Cold Tongue

2014 ◽  
Vol 43 (11) ◽  
pp. 3179-3199 ◽  
Author(s):  
Rebecca Hummels ◽  
Marcus Dengler ◽  
Peter Brandt ◽  
Michael Schlundt
Keyword(s):  
Heat Flux ◽  
Mixed Layer ◽  
Heat Budget ◽  
Cold Tongue ◽  
Mixed Layer Heat Budget ◽  
Atlantic Cold Tongue

scholarly journals Halocarbon emissions and sources in the equatorial Atlantic Cold Tongue

2015 ◽  
Vol 12 (7) ◽  
pp. 5559-5608 ◽  
Author(s):  
H. Hepach ◽  
B. Quack ◽  
S. Raimund ◽  
T. Fischer ◽  
E. L. Atlas ◽  
...  
Keyword(s):  
Surface Water ◽  
Mixed Layer ◽  
Global Radiation ◽  
Surface Mixed Layer ◽  
Cold Tongue ◽  
Equatorial Atlantic ◽  
Tropical Ocean ◽  
Near Surface ◽  
Biological Source ◽  
Atlantic Cold Tongue

Abstract. Halocarbons from oceanic sources contribute to halogens in the troposphere, and can be transported into the stratosphere where they take part in ozone depletion. This paper presents distribution and sources in the equatorial Atlantic from June and July 2011 of the four compounds bromoform (CHBr3), dibromomethane (CH2Br2), methyl iodide (CH3I) and diiodomethane (CH2I2). Enhanced biological production during the Atlantic Cold Tongue (ACT) season, indicated by phytoplankton pigment concentrations, led to elevated concentrations of CHBr3 of up to 44.7 pmol L−1 and up to 9.2 pmol L−1 for CH2Br2 in surface water, which is comparable to other tropical upwelling systems. While both compounds correlated very well with each other in the surface water,CH2Br2 was often more elevated in greater depth than CHBr3, which showed maxima in the vicinity of the deep chlorophyll maximum. The deeper maximum of CH2Br2 indicates an additional source in comparison to CHBr3 or a slower degradation of CH2Br2. Concentrations of CH3I of up to 12.8 pmol L−1 in the surface water were measured. In contrary to expectations of a predominantly photochemical source in the tropical ocean, its distribution was mostly in agreement with biological parameters, indicating a~biological source. CH2I2 was very low in the near surface water with maximum concentrations of only 3.7 pmol L−1, and the observed anticorrelation with global radiation was likely due to its strong photolysis. CH2I2 showed distinct maxima in deeper waters similar to CH2Br2. For the first time, diapycnal fluxes of the four halocarbons from the upper thermocline into and out of the mixed layer were determined. These fluxes were low in comparison to the halocarbon sea-to-air fluxes. This indicates that despite the observed maximum concentrations at depth, production in the surface mixed layer is the main oceanic source for all four compounds and has an influence on emissions into the atmosphere. The calculated production rates of the compounds yield 34 (CHBr3), 10 (CH2Br2), 21 (CH3I) and 384 (CH2I2) pmol m−3 h−1 in the whole mixed layer.

scholarly journals Halocarbon emissions and sources in the equatorial Atlantic Cold Tongue

2015 ◽  
Vol 12 (21) ◽  
pp. 6369-6387 ◽  
Author(s):  
H. Hepach ◽  
B. Quack ◽  
S. Raimund ◽  
T. Fischer ◽  
E. L. Atlas ◽  
...  
Keyword(s):  
Surface Water ◽  
Mixed Layer ◽  
Surface Mixed Layer ◽  
Cold Tongue ◽  
Equatorial Atlantic ◽  
Tropical Ocean ◽  
Near Surface ◽  
Biological Source ◽  
First Time ◽  
Atlantic Cold Tongue

Abstract. Halocarbons from oceanic sources contribute to halogens in the troposphere, and can be transported into the stratosphere where they take part in ozone depletion. This paper presents distribution and sources in the equatorial Atlantic from June and July 2011 of the four compounds bromoform (CHBr3), dibromomethane (CH2Br2), methyl iodide (CH3I) and diiodomethane (CH2I2). Enhanced biological production during the Atlantic Cold Tongue (ACT) season, indicated by phytoplankton pigment concentrations, led to elevated concentrations of CHBr3 of up to 44.7 and up to 9.2 pmol L−1 for CH2Br2 in surface water, which is comparable to other tropical upwelling systems. While both compounds correlated very well with each other in the surface water, CH2Br2 was often more elevated in greater depth than CHBr3, which showed maxima in the vicinity of the deep chlorophyll maximum. The deeper maximum of CH2Br2 indicates an additional source in comparison to CHBr3 or a slower degradation of CH2Br2. Concentrations of CH3I of up to 12.8 pmol L−1 in the surface water were measured. In contrary to expectations of a predominantly photochemical source in the tropical ocean, its distribution was mostly in agreement with biological parameters, indicating a biological source. CH2I2 was very low in the near surface water with maximum concentrations of only 3.7 pmol L−1. CH2I2 showed distinct maxima in deeper waters similar to CH2Br2. For the first time, diapycnal fluxes of the four halocarbons from the upper thermocline into and out of the mixed layer were determined. These fluxes were low in comparison to the halocarbon sea-to-air fluxes. This indicates that despite the observed maximum concentrations at depth, production in the surface mixed layer is the main oceanic source for all four compounds and one of the main driving factors of their emissions into the atmosphere in the ACT-region. The calculated production rates of the compounds in the mixed layer are 34 ± 65 pmol m−3 h−1 for CHBr3, 10 ± 12 pmol m−3 h−1 for CH2Br2, 21 ± 24 pmol m−3 h−1 for CH3I and 384 ± 318 pmol m−3 h−1 for CH2I2 determined from 13 depth profiles.

scholarly journals A model study of the seasonal mixed layer heat budget in the equatorial Atlantic

2006 ◽  
Vol 111 (C6) ◽  
Author(s):  
Anne-Charlotte Peter ◽  
Matthieu Le Hénaff ◽  
Yves du Penhoat ◽  
Christophe E. Menkes ◽  
Frédéric Marin ◽  
...  
Keyword(s):  
Mixed Layer ◽  
Heat Budget ◽  
Equatorial Atlantic ◽  
Model Study ◽  
Mixed Layer Heat Budget

scholarly journals Intraseasonal Modulation of the Surface Cooling in the Gulf of Guinea

2013 ◽  
Vol 43 (2) ◽  
pp. 382-401 ◽  
Author(s):  
Julien Jouanno ◽  
Frédéric Marin ◽  
Yves du Penhoat ◽  
Jean-Marc Molines
Keyword(s):  
Mixed Layer ◽  
Gravity Waves ◽  
Heat Budget ◽  
Vertical Shear ◽  
Upper Ocean ◽  
Equatorial Waves ◽  
Gulf Of Guinea ◽  
The Core ◽  
Mixed Layer Heat Budget ◽  
Inertia Gravity Waves

Abstract A regional numerical model of the tropical Atlantic Ocean and observations are analyzed to investigate the intraseasonal fluctuations of the sea surface temperature at the equator in the Gulf of Guinea. Results indicate that the seasonal cooling in this region is significantly shaped by short-duration cooling events caused by wind-forced equatorial waves: mixed Rossby–gravity waves within the 12–20-day period band, inertia–gravity waves with periods below 11 days, and equatorially trapped Kelvin waves with periods between 25 and 40 days. In these different ranges of frequencies, it is shown that the wave-induced horizontal oscillations of the northern front of the mean cold tongue dominate the variations of mixed layer temperature near the equator. But the model mixed layer heat budget also shows that the equatorial waves make a significant contribution to the mixed layer heat budget through modulation of the turbulent cooling, especially above the core of the Equatorial Undercurrent (EUC). The turbulent cooling variability is found to be mainly controlled by the intraseasonal modulation of the vertical shear in the upper ocean. This mechanism is maximum during periods of seasonal cooling, especially in boreal summer, when the surface South Equatorial Current is strongest and between 2°S and the equator, where the presence of the EUC provides a background vertical shear in the upper ocean. It applies for the three types of intraseasonal waves. Inertia–gravity waves also modulate the turbulent heat flux at the equator through vertical displacement of the core of the EUC in response to equatorial divergence and convergence.

Estimating uncertainties on a Gulf Stream mixed-layer heat budget from stochastic modeling

2015 ◽  
Vol 150 ◽  
pp. 66-79 ◽  
Author(s):  
Nadia K. Ayoub ◽  
Marc Lucas ◽  
Pierre De Mey
Keyword(s):  
Stochastic Modeling ◽  
Mixed Layer ◽  
Gulf Stream ◽  
Heat Budget ◽  
Mixed Layer Heat Budget
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