青藏高原UT/LS夏季CO的季节内变化特征及可能影响因子分析

CHARACTERISTICS OF UT/LS CARBON MONOXIDE INTRASEASONAL OSCILLATIONS AND THEIR ASSOCIATED FACTORS OVER THE TIBETAN PLATEAU AND ITS ADJACENT AREAS IN SUMMER

基于2005、2006年夏季大气微波临边探测仪(MLS)探测的青藏高原上对流层-下平流层(UT/LS)一氧化碳(CO)和臭氧浓度数据,分析了其浓度的季节内变化特征并对可能机制进行了初步探讨。结果表明,青藏高原及其周边区域UT/LS是大气痕量成分的异常区,具有对流层特性的一氧化碳和具有平流层特性的臭氧在时间变化呈现出反位相变化特征;UT/LS大气成分的变化存在两个主要季节内振荡(ISO)周期,即10～20天和30～60天,但不同的高度上具有不同的表现特征,UT主要表现为10～20天的季节内振荡,而LS主要表现为30～60天的季节内振荡;这两个振荡周期分别和夏季对流活动以及南亚高压的季节内变化具有同位相特征,说明上述两个因子可能是影响该区域不同高度的大气痕量成分季节内振荡的两个主要动力过程。

Tracer intraseasonal variability and its possible mechanisms in the upper troposphere and lower stratosphere（UT/LS） over Tibetan Plateau and its adjacent areas（TP） are investigated using Aura Microwave Limb Sounder（MLS） measurements of carbon monoxide（CO） and ozone during Northern Hemisphere summer（June to August） of 2005 and 2006.Observations show a persistent constituent extreme extending into the lower stratosphere throughout summer.The analysis also shows a temporally reversed phase variation between the carbon monoxide and ozone in UT/LS.The intraseasonal oscillations（ISOs） of atmospheric chemical constituents during summer are investigated with a wavelet method.It is found that intraseasonal cycles over the TP have periods of 10～20 days and 30～60 days.The former was mainly present in UT while the latter in LS.Further analysis shows that these two periods of ISOs in UT and LS are mainly in phase to the activities of convection over the south of TP and the variation of south Asian high respectively.The above two factors and their dynamical coupling may be responsible for the tracer ISOs at different levels.