山体效应是隆起的山体所产生的热力效应,其结果之一就是相同垂直带界限自外围向内部有升高的趋势.本文结合MOD11 C3地表温度产品和地面144个气象台站实测气象数据,估算青藏高原内外相同高度上的温差(也即高原山体效应值).具体结论如下:(1)最大温差(10.04℃～11.70℃)出现在高原中南部,即雅鲁藏布江以北藏北高原以南.由此为核心向北、向东、向西均逐渐减小;(2)数据点上同高度内外温差与局部基面高度有紧密关系,基面高度每抬升100 m,温差增加约0.051℃,并有加速增大的趋势;(3)山体基面高度与山体效应存在明显的线性关系,其决定系数R2高达0.5306.但山体基面高度最高的区域山体效应并非最大,说明还有其他因子影响山体效应的大小,可能的因子包括大气湿度、纬度、地形开阔程度等,在建立山体效应数字模型时必须加以考虑;(4)高原山体效应对雪线分布高度的抬升作用更甚于其对林线.山体效应估值最大的区域,分布着6000m以上极高雪线;最高林线(4 900 m)分布于本研究中山体效应估算值较低的相对多雨区,因为林线的发育还要求一定的降水量.%This paper deals with the magnitude and distribution pattern of Mass Elevation Effect (MEE) in the Tibetan Plateau by comparing temperature differences between the inner and outer parts of the Plateau (abbreviated as inner-outer Plateau) at the same elevation.It utilized MODIS land surface temperature product (MODllC3),observed meteorological data,and 57 partitioned data with different Mountain Basal Elevations (MBE,extracted from ASTER GDEM) for estimation of temperature differences.MOD11C3 data were calibrated with observed temperatures from 144 meteorological stations in the Plateau.For temperature values collected at stations out of the Plateau,they were converted to the corresponding free-air temperatures exactly at the same elevation as the inner-Plateau stations based on lapse-rate of air temperature.Temperature differences between the inner-outer Plateaus were defined as MEE value.Main conclusions are as follows:(1) the broadest temperature difference (10.04℃ ～11.70℃) between the inner-outer Plateaus was located in the middle south of the Plateau,between the Yarlung Zangbo river and the Qiangtang Plateau;(2) the simple average MBE of the Plateau was 3 625.16 m,and the average inner-outer temperature difference was 2.482℃;(3) MBE had a close relationship with temperature difference,with a coefficient of determination (R2) as high as 0.5306.However,the highest MEE did not occur in the regions with the highest MBE.This means that other unknowns also play an important role in influencing the magnitude of MEE,and they must be taken into account in the future study;(4) the impact of MEE on snowline elevation appeared to be larger than it did on timberline in the Plateau.The place where the highest snowline (6 000 ～6 200 m) in the northern hemisphere occurs was just the location where the highest MEE was estimated (5.01 ～11.70℃).The highest timberline (4 900 m) of the northern hemisphere did not developed in the highest MEE areas,instead at where the high MEE was characterized with a certain of precipitation.An interpretation for the abnormality was suggested that the development of timberline should require a certain amount of rainfall (at least 350 mm) in the high mountains.
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