Preliminary Study on the Structure of the Atmospheric Surface Layer in Mizuho Plateau, East Antarctica (Special Issue of the Proceedings of the First Symposium on Antarctic Meteorology and Glaciology)

• Main Authors: 佐々木 浩, Hiroshi SASAKI
• Format: Report
• Language: English
• Published: 日本気象協会北海道支部 1979
• Subjects: 551.5; Antarctic; East Antarctica; Syowa Station; South Pole; Mizuho; Mizuho Station; Mizuho Plateau; Sastrugi; Antarc*; Antarctica; South pole
• Online Access: https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=8097; http://id.nii.ac.jp/1291/00008097/; https://nipr.repo.nii.ac.jp/?action=repository_action_common_download&item_id=8097&item_no=1&attribute_id=18&file_no=1

1972年6月から12月までの期間にみずほ基地で行った風と気温の鉛直分布および乱流の観測結果に基づき,東南極のみずほ高原における接地気層の構造について予備的研究を行った.その結果,次のことがわかった.1)みずほ高原におけるこの期間の接地気層の安定度の特徴は,弱安定状態の出現率が高く,不安定状態の出現率が低いことといえる.2)粗度長の平均値は,0.24cmで,昭和基地と南極点での値より1桁大きな値を示した.これは,みずほ高原でのカタバティック風の風食作用によって形成される高いサストルキの存在によるものと思われる.雪面付近での風速の鉛直分布は,リチャードソン数が約0.1以下のとき,「対数+直線法則」に従った.3)風と気温の変動のパワースペクトル,および顕熱フラックスのコスペクトルの分布は,これまでに多くの研究者によって報告されている結果とほぼ同じであった.運動量のコスペクトル解析から,いくつかの周波数帯でプラス符号をもつ運動量輸送が行われていることが示された.カタバティック風のなかの鉛直風速変動の確率密度分布は,平均値よりも小さい側にかたよっていると推定される.4)内部彼の波動に伴って現われたと思われる,気温の周期的な変動が冬期間に観測された. A preliminary study on the structure of the atmospherlc surface layer in Mlzuho Plateau, East Antarctica was made based on the profiles and fluctuations of wind and air temperature observed at Mizuho Station during the period from June to December 1972 The results are summarized as follows : 1) High frequency of slightly stable conditions and low frequency of unstable conditions were a characteristic feature of stability in the atmospheric surface layer in Mizuho Plateau during the period described above 2) Mean value of roughness length was 0.24 cm and larger by one order than the values at Syowa Station and the South Pole. This may be explained by the presence of high sastrugi produced by erosion of katabatic winds in Mizuho Plateau The profiles of wind speed near the snow surface followed the "log+lmear" law for Richardson numbers less than about 0.1 3)The distributions of the power soectra of wind and temperature fluctuations and those of the cospectra of heat flux were similar to the results reported by many investigators. The cospectral analysis for momentum shows that the momentum with positive sign is transferred within some frequency ranges. It appears that the probability density distributions of the vertical velocity fluctuations in katabatic winds are skew to the region smaller than the mean values 4) Temperature oscillations which seem to be caused by internal wave motions were observed in winter.