Dh. Bromwich et Z. Liu, AN OBSERVATIONAL STUDY OF THE KATABATIC WIND CONFLUENCE ZONE NEAR SIPLE COAST, WEST ANTARCTICA, Monthly weather review, 124(3), 1996, pp. 462-477
A month-long field program to study the springtime katabatic wind conf
luence zone (where katabatic winds converge) has been carried out near
Siple Coast, West Antarctica. Based on previous observations and nume
rical studies, two surface camps, Upstream B (83.5 degrees S, 136.1 de
grees W) and South Camp (84.5 degrees S, 134.3 degrees W), were establ
ished. Ground-based remote sensing equipment(sodar and RASS), along wi
th conventional observations, were used. Combining the analyses of sur
face observations and wind and temperature profiles at the above camps
, the following picture for the cross-sectional structure of the confl
uence zone emerges. A relatively cold katabatic airflow, which probabl
y comes from East Antarctica, occupies the layer between the surface a
nd roughly 500 m AGL. Low-level jets are present below 200 m AGL and a
re stronger near the Transantarctic Mountains. Diurnal variation is pr
esent in this cold drainage flow and decreases toward the Transantarct
ic Mountains. Weak-inversion-layer tops are found near 500 m AGL, whic
h is roughly equal to the depth of the cold katabatic Bow. The warmer
West Antarctic katabatic airflow overlies the cold drainage Bow from E
ast Antarctica and has a depth of approximately 1000 m at Upstream B a
nd more than 1500 m at South Camp; this is caused by blocking of the c
onverging West Antarctic airflow by the Transantarctic Mountains. This
warm flow originates near the surface far upslope in the vicinity of
Byrd Station (80 degrees S, 120 degrees W). A baroclinic zone, formed
where the two drainage flows are horizontally adjacent, appears to bec
ome unstable with some frequency to generate mesoscale cyclones.