全球植被叶面积指数对温度和降水的响应研究

利用一套新的遥感信息反演的叶面积指数(LAI)数据和生物气候数据,建立了全球尺度的LAI与降水及温度的总体相关和距平相关,用以揭示全球尺度的植被季节和年际的变化对气候变化的响应特征.结果发现,全球尺度植被与气候因子的季节和年际变化随不同的生态系统差异明显.植被LAI与温度的总体正相关的最大值出现在北半球的中高纬度地区;LAI与降水的总体正相关高值(＞0.8)出现在亚洲东部、北美洲北部腹地和热带非洲北部的Sahel地区;最大的LAI与温度的正距平相关(0.4-0.6)出现在东南亚南部、非洲Sahel地区的南部和巴西东部等热带地区;而从LAI与降水的距平相关来看,最明显的特征是出现在西伯利亚、亚洲北部和北美西北部的强的负距平相关.本文进一步阐明了出现相关特征差异的陆-气过程物理机制.

GLOBAL RESPONDENCE ANALYSIS OF LAI VERSUS SURFACE AIR TEMPERATURE AND PRECIPITATION VARIATIONS

The newly released ISLSCP Ⅱ/LAI dataset,and temperature and precipitation datasets produced by ECMWF and CMAP are used in this paper. Correlations of LAI with temperature and precipitation were calculated separately using statistical linear correlations. Both monthly total（seasonal cycle included） and monthly anomaly（seasonal cycle removed）correlations were calculated. The results show a high correlation between the annual cycles of temperature and LAI in middle and high latitudes of the Northern Hemisphere. The largest anomaly correlations,approximately 0.4 to 0.6,tend to occur in the tropics. The other relatively large values occur in Qinghai Xizang plateau,Siberia,other extreme northern regions,and northwestern U. S..The largest extra tropical LAI precipitation correlations（>0.78） occur in eastern Asia,the interior of northern North America,and Sahel region. The strongest negative correlations occur over some regions of middle and high latitudes,e.g.,northwestern U. S.,middle Asia,and China. The most significant feature of LAI precipitation anomaly correlations is the negative anomaly correlations in Siberia,northern Asia,and northwestern North America. The results indicate that sensitivity of LAI to climatic index is different in various ecosystem with global scale. In addition,it could be useful for us to understand LAI role in land surface process as well as climate model and ecosystem research.