纵向岭谷区“通道-阻隔”作用下气温和降雨的空间分布特征

Influences of Corridor-barrier Function on the Spatial Characteristics of Temperature and Precipitation in the Longitudinal Range-Gorge Region(LRGR)

通过对纵向岭谷区1960-2000年气象数据资料的统计分析,探讨了纵向岭谷对气温和降雨量的通道阻隔作用。结果表明:纵向岭谷区准南北走向的山岭对西南气流具有较强的阻隔效应,导致西侧区域出现大面积的多雨区域(年降雨量在1 500-2 000 mm左右);纵向岭谷区的河谷地带呈现显著的通道效应,表现在南、中部,河谷区域从南向北,呈现暖舌和湿舌分布;而在北部,河谷区域从北向南出现冷舌和少雨区域;因此纵向河谷的通道效应在热力作用上表现为,南部有利于暖空气向北输送,而北部有利于冷空气向南输送;在水湿效应上,南部同样呈现水汽输送通道作用,有利于水汽向北输送;但在北部则由于高大山脉背风坡的雨影或焚风效应,导致河谷区域降雨呈现减少趋势。另外,纵向岭谷对于降雨量分布格局变化的作用较强于气温;雨季,纵向岭谷山间河谷对水汽的“通道”效应明显,造成的年降雨量差值可>200 mm;干季,纵向岭谷对冷空气的屏障“阻隔”效应明显,引起的气温差值最大可达3℃;年平均而言,纵向岭谷对年降雨的“阻隔”作用最为显著,年降雨量差值可>1 000 mm。

Located in north-south directed mountains and valleys in Southwestern China, mainly in Yunnan Province,under the comprehensive conditions of environmental pattern on landform, climate, water, soil, vegetation as well as human activity, the Longitudinal Range-Gorge Region （LRGR） behaves the important corridor-barrier function which has attracted a great deal of interest from many geologists and ecologists. Based on the observational data of monthly air temperature and precipitation in the longitudinal range-gorge region, and using the statistics of 1960 -2000, the spatial distribution characteristics of temperature and precipitation under the role of the longitudinal range-gorge are investigated. The results show that annual precipitation of western regions is bigger than the eastern regions because the longitudinal range-gorge separates southwest monsoon. Influence of corridor function is signifi- cant in river valley. It transports northwardly warm monsoon in the south region, and transports southwardly cold monsoon in the north region. The water vapor gradually reduces in the process of intruding southwest air mass moving to north, while there is little precipitation in the north part located the leeward slope of longitudinal range-gorge and influenced by the foehn. The action of the longitudinal range-gorge on the average air temperature distribution is smaller than the annual precipitation. The longitudinal range-gorge separates southwest monsoon is bigger, but separates northeast monsoon is smaller. The annual precipitation of southern and western regions is bigger than the ones of the northern and eastern regions, and the average air temperature of western part is lower than the ones of eastern part.