Sponsor
This work was funded by the National Science Foundation, Office of Polar Programs, grant OPP-0086645, and by the NASA Exobiology Program.
Published In
Journal of Geophysical Research--Atmospheres
Document Type
Article
Publication Date
1-14-2004
Subjects
Katabatic winds -- Antarctica, McMurdo Dry Valleys (Antarctica), Climatology -- Antarctica
Abstract
Katabatic winds dramatically affect the climate of the McMurdo dry valleys, Antarctica. Winter wind events can increase local air temperatures by 30°C. The frequency of katabatic winds largely controls winter (June to August) temperatures, increasing 1°C per 1% increase in katabatic frequency, and it overwhelms the effect of topographic elevation (lapse rate). Summer katabatic winds are important, but their influence on summer temperature is less. The spatial distribution of katabatic winds varies significantly. Winter events increase by 14% for every 10 km up valley toward the ice sheet, and summer events increase by 3%. The spatial distribution of katabatic frequency seems to be partly controlled by inversions. The relatively slow propagation speed of a katabatic front compared to its wind speed suggests a highly turbulent flow. The apparent wind skip (down-valley stations can be affected before up-valley ones) may be caused by flow deflection in the complex topography and by flow over inversions, which eventually break down. A strong return flow occurs at down-valley stations prior to onset of the katabatic winds and after they dissipate. Although the onset and termination of the katabatic winds are typically abrupt, elevated air temperatures remain for days afterward. We estimate that current frequencies of katabatic winds increase annual average temperatures by 0.7° to 2.2°C, depending on location. Seasonally, they increase (decrease) winter average temperatures (relative humidity) by 0.8° to 4.2° (−1.8 to −8.5%) and summer temperatures by 0.1° to 0.4°C (−0.9% to −4.1%). Long-term changes of dry valley air temperatures cannot be understood without knowledge of changes in katabatic winds.
DOI
10.1029/2003JD003937
Persistent Identifier
http://archives.pdx.edu/ds/psu/7393
Publisher
American Geophysical Union
Citation Details
Nylen, T. H., A. G. Fountain, and P. T. Doran (2004), Climatology of katabatic winds in the McMurdo dry valleys, southern Victoria Land, Antarctica, J. Geophys. Res., 109, D03114, doi:10.1029/2003JD003937.
Description
Copyright 2004 American Geophysical Union