跨南大洋经向断面的大气垂直剖面特征研究

基于中国第29次南极科学考察期间获取的GPS探空观测数据,分析了东南印度洋和西南太平洋经向断面大气垂直结构的基本特征、季节变化和纬向差异。不同断面的大气垂向结构差异显著,但也具有共同特征,4000 m以下低空的气温和湿度明显高于高空,而低空风速明显小于高空风速,8000 m以上高空各个观测要素的垂直变化较小,整个断面主要以西风为主,整个垂直剖面湿度异常偏高(偏低)的区域通常对应上升(下沉)气流。给出了3个观测断面的大气锋面位置和类型,P1断面的大气锋面在47°~50°S,P2和P3断面的大气锋面在52°~58°S,P1和P2的锋面属于暖锋,P3的锋面由于气旋的影响分类不明显。东南印度洋大气剖面结构具有明显的季节变化,秋季和春季相比,秋季具有风速小,气温高特征,大气锋面更加偏南。东南印度洋和西南太平洋断面的大气剖面结构差异明显,二者相比,东南印度洋具有风速大、气温高及相对湿度小的特征,但大气锋面位置相同。

Characteristic of the Atmospheric Vertical Profiles Across the Meridional Section Over the Southern Ocean

This study analyzed the basic characteristic,seasonal change and meridional variation of the atmospheric vertical structure in the southeast Indian Ocean and the southwest Pacific based on the air sounding observations obtained during the 29th Chinese National Antarctic Research Expedition(CHNARE).Although the atmospheric vertical structures are obviously different among those sections,there are still some common features.The air temperature and relevant humidity below 4000m are obviously higher than those in higher level,but the wind speed is smaller in lower level.The vertical changes of all the observational parameters above 8000m are very small,and almost all the sections are dominated by westerly winds.The area with particular high(low)vertical humidity profiles usually have upwelling(downwelling)convection.The position and type of the atmosphere fronts in the three sections are shown.The atmosphere front of P1 section is located between 47°~50°S,while those of P2 and P3 sections are located between 52°~58°S.Both of the fronts of P1 and P2 sections are warm fronts,but the front type of P3 section is not clear due to the impact of anonymous cyclone.The atmospheric vertical structure in the southeast Indian Ocean exhibits obvious seasonal change.The wind speed(air temperature)is smaller(higher)during austral autumn compared to austral spring.The atmospheric front position in austral autumn is further south than austral spring.The atmospheric vertical structures are different in the southeast Indian Ocean and the southwest Pacific.Both the wind speed and air temperature are higher in the southeast Indian Ocean than the southwest Pacific,while the relative humidity is smaller in the southeast Indian Ocean,but the atmospheric front positions of these two sections are almost same.