scholarly journals Seasonal mixed layer heat budget of the tropical Atlantic Ocean

2003 ◽  
Vol 108 (C5) ◽  
Author(s):  
Gregory R. Foltz
Keyword(s):  
Atlantic Ocean ◽  
Mixed Layer ◽  
Heat Budget ◽  
Tropical Atlantic ◽  
Tropical Atlantic Ocean ◽  
Mixed Layer Heat Budget

scholarly journals Modelling the vertical distribution of bromoform in the upper water column of the tropical Atlantic Ocean

2009 ◽  
Vol 6 (4) ◽  
pp. 535-544 ◽  
Author(s):  
I. Hense ◽  
B. Quack
Keyword(s):  
Atlantic Ocean ◽  
Water Column ◽  
Mixed Layer ◽  
Surface Mixed Layer ◽  
Tropical Atlantic ◽  
Tropical Atlantic Ocean ◽  
Subsurface Maximum ◽  
The Vertical Distribution ◽  
Production Layer ◽  
Inverse Proportionality

Abstract. The relative importance of potential source and sink terms for bromoform (CHBr3) in the tropical Atlantic Ocean is investigated with a coupled physical-biogeochemical water column model. Bromoform production is either assumed to be linked to primary production or to phytoplankton losses; bromoform decay is treated as light dependent (photolysis), and in addition either vertically uniform, proportional to remineralisation or to nitrification. All experiments lead to the observed subsurface maximum of bromoform, corresponding to the subsurface phytoplankton biomass maximum. In the surface mixed layer, the concentration is set by entrainment from below, photolysis in the upper few meters and the outgassing to the atmosphere. The assumed bromoform production mechanism has only minor effects on the solution, but the various loss terms lead to significantly different bromoform concentrations below 200 m depth. The best agreement with observations is obtained when the bromoform decay is coupled to nitrification (parameterised by an inverse proportionality to the light field). Our model results reveal a pronounced seasonal cycle of bromoform outgassing, with a minimum in summer and a maximum in early winter, when the deepening surface mixed layer reaches down into the bromoform production layer.

Seasonal Cycle of the Mixed Layer Heat Budget in the Northeastern Tropical Atlantic Ocean

2013 ◽  
Vol 26 (20) ◽  
pp. 8169-8188 ◽  
Author(s):  
Gregory R. Foltz ◽  
Claudia Schmid ◽  
Rick Lumpkin
Keyword(s):  
Mixed Layer ◽  
Annual Cycle ◽  
Turbulent Mixing ◽  
Seasonal Cycle ◽  
Heat Budget ◽  
Heat Content ◽  
Boreal Summer ◽  
Tropical Atlantic ◽  
Mixed Layer Heat Budget ◽  
Vertical Turbulent Mixing

Abstract The seasonal cycle of the mixed layer heat budget in the northeastern tropical Atlantic (0°–25°N, 18°–28°W) is quantified using in situ and satellite measurements together with atmospheric reanalysis products. This region is characterized by pronounced latitudinal movements of the intertropical convergence zone (ITCZ) and strong meridional variations of the terms in the heat budget. Three distinct regimes within the northeastern tropical Atlantic are identified. The trade wind region (15°–25°N) experiences a strong annual cycle of mixed layer heat content that is driven by approximately out-of-phase annual cycles of surface shortwave radiation (SWR), which peaks in boreal summer, and evaporative cooling, which reaches a minimum in boreal summer. The surface heat-flux-induced changes in the mixed layer heat content are damped by a strong annual cycle of cooling from vertical turbulent mixing, estimated from the residual in the heat balance. In the ITCZ core region (3°–8°N) a weak seasonal cycle of mixed layer heat content is driven by a semiannual cycle of SWR and damped by evaporative cooling and vertical turbulent mixing. On the equator the seasonal cycle of mixed layer heat content is balanced by an annual cycle of SWR that reaches a maximum in October and a semiannual cycle of turbulent mixing that cools the mixed layer most strongly during May–July and November. These results emphasize the importance of the surface heat flux and vertical turbulent mixing for the seasonal cycle of mixed layer heat content in the northeastern tropical Atlantic.

Mean and Variability of the Tropical Atlantic Ocean in the CCSM4*

2012 ◽  
Vol 25 (14) ◽  
pp. 4860-4882 ◽  
Author(s):  
Ernesto Muñoz ◽  
Wilbert Weijer ◽  
Semyon A. Grodsky ◽  
Susan C. Bates ◽  
Ilana Wainer
Keyword(s):  
Atlantic Ocean ◽  
Wind Stress ◽  
Heat Budget ◽  
South Atlantic ◽  
Tropical Atlantic ◽  
Climate System Model ◽  
Tropical Atlantic Ocean ◽  
Modes Of Variability ◽  
Sst Variability ◽  
Budget Analysis

Abstract This study analyzes important aspects of the tropical Atlantic Ocean from simulations of the fourth version of the Community Climate System Model (CCSM4): the mean sea surface temperature (SST) and wind stress, the Atlantic warm pools, the principal modes of SST variability, and the heat budget in the Benguela region. The main goal was to assess the similarities and differences between the CCSM4 simulations and observations. The results indicate that the tropical Atlantic overall is realistic in CCSM4. However, there are still significant biases in the CCSM4 Atlantic SSTs, with a colder tropical North Atlantic and a hotter tropical South Atlantic, that are related to biases in the wind stress. These are also reflected in the Atlantic warm pools in April and September, with its volume greater than in observations in April and smaller than in observations in September. The variability of SSTs in the tropical Atlantic is well represented in CCSM4. However, in the equatorial and tropical South Atlantic regions, CCSM4 has two distinct modes of variability, in contrast to observed behavior. A model heat budget analysis of the Benguela region indicates that the variability of the upper-ocean temperature is dominated by vertical advection, followed by meridional advection.

scholarly journals Seasonal mixed-layer salinity balance in the tropical Atlantic Ocean: Mean state and seasonal cycle

2013 ◽  
Vol 118 (1) ◽  
pp. 332-345 ◽  
Author(s):  
C. Y. Da-Allada ◽  
G. Alory ◽  
Y. du Penhoat ◽  
E. Kestenare ◽  
F. Durand ◽  
...  
Keyword(s):  
Atlantic Ocean ◽  
Mixed Layer ◽  
Seasonal Cycle ◽  
Tropical Atlantic ◽  
Tropical Atlantic Ocean ◽  
Salinity Balance ◽  
Mean State

scholarly journals Modelling the vertical distribution of bromoform in the upper water column of the tropical Atlantic Ocean

2008 ◽  
Vol 5 (6) ◽  
pp. 4919-4944 ◽  
Author(s):  
I. Hense ◽  
B. Quack
Keyword(s):  
Atlantic Ocean ◽  
Water Column ◽  
Mixed Layer ◽  
Surface Mixed Layer ◽  
Tropical Atlantic ◽  
Tropical Atlantic Ocean ◽  
Subsurface Maximum ◽  
The Vertical Distribution ◽  
Production Layer ◽  
Inverse Proportionality

Abstract. The relative importance of potential source and sink terms for bromoform (CHBr3) in the tropical Atlantic Ocean is investigated with a coupled physical-biogeochemical water column model. Bromoform production is either assumed to be linked to primary production or to phytoplankton losses; bromoform decay is treated as light dependent (photolysis), and in addition either vertically uniform, proportional to remineralisation or to nitrification. All experiments lead to the observed subsurface maximum of bromoform, corresponding to the subsurface phytoplankton biomass maximum. In the surface mixed layer, the concentration is set by entrainment from below, photolysis in the upper few meters and the outgassing to the atmosphere. The assumed bromoform production mechanism has only minor effects on the solution, but the various loss terms lead to significantly different bromoform concentrations below 200 m depth. The best agreement with observations is obtained when the bromoform decay is coupled to nitrification (parameterised by an inverse proportionality to the light field). Our model results reveal a pronounced seasonal cycle of bromoform outgassing, with a minimum in summer and a maximum in early winter, when the deepening surface mixed layer reaches down into the bromoform production layer.

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