Responses of the Atmospheric Boundary Layer to a Low Latitude Mesoscale SST Front

Author(s):  
Zhongkuo Zhao ◽  
Xueyan Bi ◽  
Jimy Dudhia ◽  
Yali Luo ◽  
Jinbao Song ◽  
...  
1982 ◽  
Vol 4 (2) ◽  
pp. 29-32
Author(s):  
Le Dinh Quang

The influence of the baroclinic effects on the fundamental characters of the atmospheric boundary layer atmosphere is studied. The obvious difference between the structures of boundary layer of both baroclinic and barotropic cases is presented. Especially the baroclinic effect on the low latitude may not be neglected.


2005 ◽  
Vol 18 (5) ◽  
pp. 737-753 ◽  
Author(s):  
Hollis E. Pyatt ◽  
Bruce A. Albrecht ◽  
Chris Fairall ◽  
J. E. Hare ◽  
Nicholas Bond ◽  
...  

Abstract The structure of the marine atmospheric boundary layer (MABL) over the tropical eastern Pacific Ocean is influenced by spatial variations of sea surface temperature (SST) in the region. As the MABL air is advected across a strong SST gradient associated with the cold tongue–ITCZ complex (CTIC), substantial changes occur in the thermodynamic structure, surface fluxes, and cloud properties. This study attempts to define and explain the variability in the MABL structure and clouds over the CTIC. Using data collected on research cruises from the fall seasons of 1999–2001, composite soundings were created for both the cold and warm sides of the SST front to describe the mean atmospheric boundary layer (ABL) structure and its evolution across this front. The average difference in SST across this front was ∼6°C; much of this difference was concentrated in a band only ∼50 km wide. During the fall seasons, on the cold side of the gradient, a well-defined inversion exists in all years. Below this inversion, both fair-weather cumulus and stratiform clouds are observed. As the MABL air moves over the SST front to warmer waters, the inversion weakens and increases in height. The MABL also moistens and eventually supports deeper convection over the ITCZ. Both the latent and sensible heat fluxes increase dramatically across the SST front because of both an increase in SST and surface wind speed. Cloudiness is variable on the cold side of the SST front ranging from 0.2 to 0.9 coverage. On the warm side, cloud fraction was quite constant in time, with values generally greater than 0.8. The highest cloud-top heights (>3 km) are found well north of the SST front, indicating areas of deeper convection. An analysis using energy and moisture budgets identifies the roles of various physical processes in the MABL evolution.


2005 ◽  
Vol 62 (2) ◽  
pp. 426-442 ◽  
Author(s):  
Simon P. de Szoeke ◽  
Christopher S. Bretherton ◽  
Nicholas A. Bond ◽  
Meghan F. Cronin ◽  
Bruce M. Morley

Abstract The atmospheric boundary layer (ABL) along 95°W in the eastern equatorial Pacific during boreal autumn is described using data from the East Pacific Investigation of Climate (EPIC) 2001, with an emphasis on the evolution of the thermodynamic ABL properties from the cold tongue to the cold-advection region north of the sea surface temperature (SST) front. Surface sensible and latent heat fluxes and wind stresses between 1°S and 12°N are calculated from data from eight NCAR C-130 research aircraft flights and from Tropical Atmosphere Ocean (TAO) buoys. Reduced surface wind speed and a 10 m s−1 jet at a height of 500 m are found over the equatorial cold tongue, demonstrating the dependence of the surface wind speed on surface stability. The ABL exhibits a maximum in cloud cover on the north (downwind) side of the warm SST front, at 1°–3°N. Turbulent mixing driven by both surface buoyancy flux and radiative cooling at the cloud tops plays a significant role in maintaining the depth and structure of the ABL. The ABL heat budget between the equator and 3°N is balanced by comparable contributions from advective cooling, radiative cooling, surface warming, and entrainment warming. Entrainment drying is a weak contributor to the moisture budget, relative to dry advection and surface evaporation. Both the heat and moisture budgets are consistent with a rapid entrainment rate, 12 ± 2 mm s−1, deduced from the observed rise of the inversion with latitude between 0° and 4°N.


2007 ◽  
Vol 25 ◽  
pp. 49-55 ◽  
Author(s):  
S. Argentini ◽  
I. Pietroni ◽  
G. Mastrantonio ◽  
A. Viola ◽  
S. Zilitinchevich

2012 ◽  
Vol 3 (4) ◽  
pp. 414-416
Author(s):  
M.SHANAWAZ BEGUM M.SHANAWAZ BEGUM ◽  
◽  
G.SUDHAKAR G.SUDHAKAR ◽  
D.PUNYASESHUDU D.PUNYASESHUDU

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