Studies on the Characteristics and Seasonal Variations of Precipitation Phenomena Obtained by Radar Observations at Syowa Station, Antarctica

• Main Author: Konishi, Hiroyuki
• Format: Other/Unknown Material
• Language: English
• Published: Hokkaido University
• Subjects: 400; Syowa Station; Antarc*; Antarctica; E. Antarctica
• Online Access: http://hdl.handle.net/2115/51337; https://doi.org/10.11501/3112093

Long-term observations of precipitating clouds were carried out by a vertical pointing radar, PPI radar and a 37 GHz microwave radiometer at Syowa Station (69°00'S, 40°35'E), Antarctica in 1989. The results obtained include the characteristics and seasonal variations of snowfalls. The former revealed the cause of precipitation near Syowa Station, Antarctica. It is concluded from the observations that precipitation near Syowa Station, Antarctica is mainly brought by cloud vortices associated with extratropical cyclones which advance to high latitude while developing to a mature stage. It is proposed that the outer side of the cloud vortex is composed of layer clouds above the warm front formed by warmer air advancing southward from low latitude. The warmer air is considered to be raised above the colder and drier air circulating westward around the polar high along the coast near Syowa Station, Antarctica. The inside of the vortex is compesed of convective clouds formed in colder air rotating around the low center along the welldeveloped spiral. Therefore the cloud vortex is concluded to be created by the occluded front composed of the cold front upgliding above the warm front. Precipitation from an occluded front crossing over Syowa Station was often observed when the low pressure center was stationary northwest of Syowa Station. The time-height cross sections of radar echoes in this case are considered to be normal cross sections of cloud vortex. It is concluded from the observations that the necessary conditions to bring large amount of precipitation to the coastal region near Syowa Station, Antarctica are that the low pressure system is in its mature stage, locates northwest of the region, and is stationary. Especially, a low pressure in its mature stage northwest of the station would bring a large amount of precipitation for a long time when the low pressure center moves westward in accordance with the orientation of the cloud band of cloud vortex. The seasonal variations of clouds and precipitation were ...