南极Dome A至普里兹湾沿岸下降风特征

Characteristics of katabatic winds from Dome A to the coast of Prydz Bay,Antarctica

本文利用我国极地数值天气预报系统和美国南极中尺度预报系统的存档数据,分析了Dome A至普里兹湾沿岸地区下降风风场的时空分布和大气质量通量,给出了该地区下降风的基本特点。该地区下降风受南极冰盖地形影响强烈,艾默里冰架西侧等陡峭地区风速总体较大;下降风随季节变化较大,冬季的下降风较强。强下降风在前进过程中有绝热增温现象,并给艾默里冰架西部带来近表层升温。下降风风速最大处位于地面以上约100~200 m高度,风速较大地区的下降风在垂直方向上分布较为深厚。下降风在普里兹湾沿岸的表层大气质量通量在时空分布上极不均匀,艾默里冰架西侧的下降风气流较强时,普里兹湾海域有较多的中尺度气旋活动。下降风引发普里兹湾中尺度气旋旋生的过程值得关注,需进一步研究下降风引发中尺度气旋的机理。

Using archived data from Chinese Polar Numerical Weather Forecasting System(PNWFS)and America Antarctic Mesoscale Prediction System,the spatial and temporal distribution of katabatic winds and air mass flux from Dome A to the coast of Prydz Bay are analyzed,and basic characteristics of katabatic winds in the region are depicted.It is found that the katabatic winds in this area is strongly affected by the terrain of the Antarctica ice sheet.Steep terrain such as the western side of the Amery Ice Shelf sees stronger katabatic winds than smooth terrain does;and the katabatic winds vary greatly with the season for temporal distribution with stronger winds in winter.Adiabatic warming,which can be found in the area where strong katabatic winds flow,causes increasing of near surface temperature at the Amery Ice Shelf.The maximum katabatic wind speed zone is located at a height of about 100 m to 200 m above the ground.Katabatic winds extents to higher altitudes while surface winds are stronger.The surface air mass flux of the katabatic winds along the coast of the Prydz Bay is extremely uneven in spatial and temporal distribution.Strong katabatic winds in the Amery Ice Shelf are linked to more mesoscale cyclone activities in the Prydz Bay waters.The process of mesoscale cyclones induced by katabatic winds in the Prydz Bay is worthy of attention,thus the mechanism of cyclogenesis forced by katabatic winds needs further notice.