Dark streams observed on NOAA satellite images over the Katabatic wind zone, Antarctica

• Main Authors: Tatsuo Endoh, Takashi Yamanouchi, Takayuki Ishikawa, Hideo Kakegawa, Sadao Kawaguchi
• Format: Article in Journal/Newspaper
• Language: English
• Published: National Institute of Polar Research 1997
• Subjects: geo; envir; Antarc*; Antarctica
• Online Access: https://doi.org/10.15094/00008988; https://doaj.org/article/d443f19386cf4ecbb6a3bfadbb601bda

In the katabatic wind zone in Antarctica, some characteristic streams are frequently observed in NOAA satellite images especially in the winter season. We call these "dark streams" in this work. These dark streams are observed to move and change location and their width slightly in a series of succesive scenes of NOAA images; however, distributions seem to be restricted to areas of some specific topographies. We measured air temperature and wind speed at one point by means of one of our AWS (Automated Weather Station) system. Air temperature was not particularly low and remained steady, and wind speed was constantly high, 13m/s or more. TBB analyzed from NOAA AVHRR may provide surface temperatures which are thought to be proportional to the air temperature which is equalized to emittance temperature of the blowing and drifting snow particles. On the basis of these data, air temperature inside the stream was 15℃ or higher than that outside. Along the central line of the stream, air temperature was analyzed to vary with height at the dry adiabatic lapse rate. From these observational results it may be considered that these dark stream images are composed of a warmer air stream compared with that of the outside and a strongly forced downward current along the slope.