The Dynamics of Ascent-Forced Orographic Convection in the Tropics: Results from DominicaSource: Journal of the Atmospheric Sciences:;2013:;Volume( 070 ):;issue: 012::page 4067DOI: 10.1175/JAS-D-13-016.1Publisher: American Meteorological Society
Abstract: he mountainous Caribbean island of Dominica was chosen as a natural laboratory for studying orographic convection in the tropics. Here, the authors focus on a prototypical case study, taken from the Dominica Experiment (DOMEX) field campaign in the spring of 2011. Airborne measurements and high-resolution numerical experiments are used to examine the mesoscale dynamics of moist airflow over Dominica and its relationship to convection, turbulence, and rainfall.Upwind of the island, there is minimal lateral deflection or lifting of the flow, largely because of latent heat release in the overisland convection. Over the terrain, forced ascent leads to rapid development of moist convection, buoyancy-generated turbulence, and rainfall. Although this convection produces sporadic bursts of heavy rainfall, it does not appear to enhance the time-mean rainfall. Over the lee slopes, a dry plunging flow produces anisotropic shear-generated turbulence and strong low-level winds while quickly dissipating convection and rainfall. In the wake, low-level air is decelerated, both by turbulence in the plunging flow and by frictional drag over the island. Low-level wake air is also dried and warmed, primarily by turbulent vertical mixing and regional descent, both associated with the downslope flow. Rainfall and latent heating play only a secondary role in warming and drying the wake.
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contributor author | Minder, Justin R. | |
contributor author | Smith, Ronald B. | |
contributor author | Nugent, Alison D. | |
date accessioned | 2017-06-09T16:56:27Z | |
date available | 2017-06-09T16:56:27Z | |
date copyright | 2013/12/01 | |
date issued | 2013 | |
identifier issn | 0022-4928 | |
identifier other | ams-76776.pdf | |
identifier uri | http://onlinelibrary.yabesh.ir/handle/yetl/4219260 | |
description abstract | he mountainous Caribbean island of Dominica was chosen as a natural laboratory for studying orographic convection in the tropics. Here, the authors focus on a prototypical case study, taken from the Dominica Experiment (DOMEX) field campaign in the spring of 2011. Airborne measurements and high-resolution numerical experiments are used to examine the mesoscale dynamics of moist airflow over Dominica and its relationship to convection, turbulence, and rainfall.Upwind of the island, there is minimal lateral deflection or lifting of the flow, largely because of latent heat release in the overisland convection. Over the terrain, forced ascent leads to rapid development of moist convection, buoyancy-generated turbulence, and rainfall. Although this convection produces sporadic bursts of heavy rainfall, it does not appear to enhance the time-mean rainfall. Over the lee slopes, a dry plunging flow produces anisotropic shear-generated turbulence and strong low-level winds while quickly dissipating convection and rainfall. In the wake, low-level air is decelerated, both by turbulence in the plunging flow and by frictional drag over the island. Low-level wake air is also dried and warmed, primarily by turbulent vertical mixing and regional descent, both associated with the downslope flow. Rainfall and latent heating play only a secondary role in warming and drying the wake. | |
publisher | American Meteorological Society | |
title | The Dynamics of Ascent-Forced Orographic Convection in the Tropics: Results from Dominica | |
type | Journal Paper | |
journal volume | 70 | |
journal issue | 12 | |
journal title | Journal of the Atmospheric Sciences | |
identifier doi | 10.1175/JAS-D-13-016.1 | |
journal fristpage | 4067 | |
journal lastpage | 4088 | |
tree | Journal of the Atmospheric Sciences:;2013:;Volume( 070 ):;issue: 012 | |
contenttype | Fulltext |