TY - JOUR

T1 - Structure and dynamics of the summertime atmospheric boundary layer over the Antarctic plateau: 2. Heat, moisture, and momentum budgets

AU - van As, D.

AU - van den Broeke, M.R.

N1 - Samen met ca. 40 andere auteurs

PY - 2006

Y1 - 2006

N2 - This paper presents the summertime budgets of heat, moisture and momentum in the
atmospheric boundary layer at Kohnen base (75 000S, 0 040E, 2892 m above sea level),
located in the interior of East Antarctica. For this purpose we performed a model
simulation for clear-sky conditions and constant large-scale forcing, using a high-resolution
one-dimensional atmospheric model which has been validated by observations (see van
As et al., 2006). Turbulent exchange is the dominant component in the heat budget,
heating the daytime well-mixed layer by a maximum of 1.0 K h 1. Radiative heating and
cooling are important, and are largest near the surface and just above and below the large
temperature and humidity gradients of the nighttime stable layer. Vertical heat advection,
which is introduced by the wind speed component along the slope, is the smallest heat-budget
component in the atmospheric boundary layer, but becomes significant above it. The same is
valid for vertical advection in the moisture budget, which is again dominated by turbulent
exchange in the atmospheric boundary layer. The model generates solid precipitation
(diamond dust) in the nighttime stable boundary layer. In the stable layer the temperature
deficit with respect to the free atmosphere can be larger than 10 K, forcing a relatively large
katabatic acceleration (up to 2.7ms 1 h 1). Katabatic forcing is chiefly opposed by turbulent
momentum transfer (friction). The katabatic forcing decreases with height but is nonzero
above the atmospheric boundary layer. In the nighttime stable layer we find a jet which is
chiefly forced by katabatics, and in the residual layer above it we find alternating wind
maxima and minima as a result of an inertial oscillation.

AB - This paper presents the summertime budgets of heat, moisture and momentum in the
atmospheric boundary layer at Kohnen base (75 000S, 0 040E, 2892 m above sea level),
located in the interior of East Antarctica. For this purpose we performed a model
simulation for clear-sky conditions and constant large-scale forcing, using a high-resolution
one-dimensional atmospheric model which has been validated by observations (see van
As et al., 2006). Turbulent exchange is the dominant component in the heat budget,
heating the daytime well-mixed layer by a maximum of 1.0 K h 1. Radiative heating and
cooling are important, and are largest near the surface and just above and below the large
temperature and humidity gradients of the nighttime stable layer. Vertical heat advection,
which is introduced by the wind speed component along the slope, is the smallest heat-budget
component in the atmospheric boundary layer, but becomes significant above it. The same is
valid for vertical advection in the moisture budget, which is again dominated by turbulent
exchange in the atmospheric boundary layer. The model generates solid precipitation
(diamond dust) in the nighttime stable boundary layer. In the stable layer the temperature
deficit with respect to the free atmosphere can be larger than 10 K, forcing a relatively large
katabatic acceleration (up to 2.7ms 1 h 1). Katabatic forcing is chiefly opposed by turbulent
momentum transfer (friction). The katabatic forcing decreases with height but is nonzero
above the atmospheric boundary layer. In the nighttime stable layer we find a jet which is
chiefly forced by katabatics, and in the residual layer above it we find alternating wind
maxima and minima as a result of an inertial oscillation.

M3 - Article

SN - 2169-897X

VL - 111

SP - D07103/1-D07103/12

JO - Journal of Geophysical Research: Atmospheres

JF - Journal of Geophysical Research: Atmospheres

ER -