scholarly journals Nitrous oxide during the onset of the Atlantic cold tongue

2017 ◽  
Vol 122 (1) ◽  
pp. 171-184 ◽  
Author(s):  
D. L. Arévalo-Martínez ◽  
A. Kock ◽  
T. Steinhoff ◽  
P. Brandt ◽  
M. Dengler ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Cold Tongue ◽  
Atlantic Cold Tongue

scholarly journals Author Correction: Sahel rainfall strength and onset improvements due to more realistic Atlantic cold tongue development in a climate model

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
S. Steinig ◽  
J. Harlaß ◽  
W. Park ◽  
M. Latif
Keyword(s):  
Climate Model ◽  
Cold Tongue ◽  
Sahel Rainfall ◽  
Atlantic Cold Tongue

Seasonal and regional variability of upper ocean diapycnal heat flux in the Atlantic cold tongue

2013 ◽  
Vol 111 ◽  
pp. 52-74 ◽  
Author(s):  
Rebecca Hummels ◽  
Marcus Dengler ◽  
Bernard Bourlès
Keyword(s):  
Heat Flux ◽  
Upper Ocean ◽  
Cold Tongue ◽  
Regional Variability ◽  
Atlantic Cold Tongue

scholarly journals Coupling between the Atlantic cold tongue and the West African monsoon in boreal spring and summer

2011 ◽  
Vol 116 (C4) ◽  
Author(s):  
Guy Caniaux ◽  
Hervé Giordani ◽  
Jean-Luc Redelsperger ◽  
Françoise Guichard ◽  
Erica Key ◽  
...  
Keyword(s):  
West African Monsoon ◽  
West African ◽  
Cold Tongue ◽  
The West ◽  
African Monsoon ◽  
Boreal Spring ◽  
Atlantic Cold Tongue

scholarly journals Main processes of the Atlantic cold tongue interannual variability

2017 ◽  
Vol 50 (5-6) ◽  
pp. 1495-1512 ◽  
Author(s):  
Yann Planton ◽  
Aurore Voldoire ◽  
Hervé Giordani ◽  
Guy Caniaux
Keyword(s):  
Interannual Variability ◽  
Cold Tongue ◽  
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 West African Monsoon (WAM) and Atlantic Cold Tongue (ACT) onsets using Regional Climate Model

2017 ◽  
Vol 12 (15) ◽  
pp. 142-154
Author(s):  
Benjamin KOUASSI K. ◽  
DIAWARA Adama ◽  
Yves KOUADIO K. ◽  
YOROBA Fidele ◽  
TOUALY Elisee
Keyword(s):  
Regional Climate Model ◽  
Climate Model ◽  
Regional Climate ◽  
West African Monsoon ◽  
West African ◽  
Cold Tongue ◽  
African Monsoon ◽  
Atlantic Cold Tongue

scholarly journals A Generalized Method for Estimating the Structure of the Equatorial Atlantic Cold Tongue: Application to Drifter Observations

2013 ◽  
Vol 30 (8) ◽  
pp. 1884-1895 ◽  
Author(s):  
Verena Hormann ◽  
Rick Lumpkin ◽  
Renellys C. Perez
Keyword(s):  
Complete Analysis ◽  
Cold Tongue ◽  
Equatorial Atlantic ◽  
Instability Waves ◽  
Tropical Instability Waves ◽  
Large Application ◽  
Coordinate Mapping ◽  
Equatorial Current ◽  
Atlantic Cold Tongue ◽  
Northern Branch

Abstract A generalized method is developed to determine the position of the Atlantic northern cold tongue front across its zonal extent from satellite sea surface temperature (SST) data. Previous approaches estimated the frontal position subjectively or individually, calling for a more objective technique that is suitable for large datasets. The developed methodology is based on a median frontal SST, and associated positional uncertainties are on the order of 0.3° latitude for the period 1998–2011. Frontal characteristics are generally consistent with tropical instability waves (TIWs) and interannual variations are large. Application to drifter observations shows how the new methodology can be used to better understand circulation features near the northern cold tongue front. A drifter pair deployed on the eastern side of a passing TIW crest north of the front revealed that the trajectories of the drifters were clearly influenced by the shape of the front and they did not cross the front, but rather stayed close together about 2.5° north of the front. In a more complete analysis using all available drifters near the Atlantic northern cold tongue front, only about 12% of the trajectories crossed the front. Analyses in an along- and cross-frontal frame of reference complement isopycnal coordinate mapping, and tropical Atlantic drifter velocities averaged in frontal coordinates indicate a broadened shear zone between the northern branch of the South Equatorial Current and North Equatorial Countercurrent as well as meridional convergence near the front.

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.

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