西南纵向岭谷地形对季风的“通道-阻隔”作用

地形格局对大气环流与区域气候具有重要影响。已有研究认为纵向岭谷区主要受到印度洋季风与太平洋季风的共同影响,二者在哀牢山山脉附近交汇,哀牢山山脉是一条重要的地理分界线。本文从大气环流、水汽输送、区域气候、河川径流以及植物稳定氧同位素等多个方面研究发现:纵向岭谷地区主要受印度洋季风的影响,太平洋季风的影响在8月份有一定的作用,但不够明显;在地形格局作用下,地表水汽、降水以及河川径流在纵向岭谷区表现出明显的纬向差异、经向延伸的特征;大流环流、水汽输送、区域气候以及河川径流等的空间差异,是特殊环境对水热再分配的结果,即"通道-阻隔"作用的效应;这些差异不是地理地带性的表现,而是非地带性作用的结果;这种"通道—阻隔"作用导致地表水热条件的再分配,是该区生态地理格局形成与演化的主驱动力之一。纵向岭谷地形对季风的"通道—阻隔"作用导致了一系列地理要素的空间分异和相关联的生态效应。

Barrier-corridor effect of longitudinal range-gorge terrain on monsoons in Southwest China

Topographic pattern has important impacts on atmospheric circulation and regional climate.The special terrain of Longitudinal Range-Gorge Region(LRGR) in Southwest China has a "corridor-barrier" effect on monsoons circulation,which led to the redistribution of surface hydrothermal pattern and is the main driving force of the formation and evolution of the ecosystems.Previous studies showed that LRGR was influenced by the combined effect of the Indian monsoon and the Pacific monsoon,which meet at the Ailaoshan mountain ranges.The Ailao Mountains are an important geographical dividing line.In this study,based on proofs of the atmospheric circulation,moisture transport,regional climate,runoff,and plant stable oxygen isotopes compostion,we found that LRGR is affected mainly by the Indian monsoon.The Pacific monsoon only affect this area in August,and the influence is not significant.Under the terrain "corridor-barrier" effect,surface water vapor,precipitation and runoff in LRGR showed significant zonal differences and meridional extension;crowd circulation,moisture transport,regional climate and river runoff.The atmospheric precipitable water,precipitation and stream flow present an apparently different pattern between the west and east sides of Ailao Mountains.The environmental differences are the results of the hydrothermal redistribution by the special terrain,which are the "barrier" and "corridor" effects of the LRGR.These differences are not the results of geographical zonality,but the results of non-zonality.The "corridor-barrier" effects of the longitudial range-gorge on monsoons result in the spatial differences of the geographical elements and the associated ecological effects.