基于植被状态指数的干旱化特征及气候驱动因素分析——以江苏省为例

干旱是危害最大的自然灾害之一,给农业生产及地区经济造成了巨大的损失。以AVHRR和MODIS遥感数据集所计算的植被状态指数(Vegetation Condition Index,VCI)为监测指标,研究江苏省干旱的时空变化特征,并结合江苏省气象站台1982~2010年的实测气象资料,分析降水量、气温、相对湿度和日照时数这四个气候因子的变化趋势及其对干旱化的影响,不仅能够定量地描述植被干旱的空间变化,还可以反映长期气候对其起到的正反作用。研究结果表明:江苏省近30年的年均VCI值呈上升趋势,区域整体旱情有所缓解;四个气候因子中,年均温度逐渐升高,年均降水量基本保持不变,年均相对湿度和日照时数则呈下降趋势,其中气温和相对湿度与VCI的相关性达极显著水平,是影响江苏省旱情的主要因素。

ANALYSIS OF DROUGHT CHARACTERISTICS AND ITS DRIVING FACTORS BASED ON VEGETATION CONDITION INDEX: A CASE STUDY IN JIANGSU PROVINCE

Drought is one of the most damaging natural disasters, which might cause huge losses to agricultural production and the local economy. Using the Vegetation Condition Index (VCI) calculated by the remote sensing data of AVHRR and MODIS as monitoring indicators to study the temporal and spatial variation in Jiangsu Province was the first step. Then, we discuss its relationship with the four climate factors about precipitation, air temperature, relative humidity and sunshine duration according to the measured meteorological data about Jiangsu Province from 1982 to 2010. Not only could quantitatively describe the space changes in vegetation drought, it could also reflect positive or negative effect by long-term climate. The results showed that the average VCI value for nearly 30 years in Jiangsu was on a rising curve, and the overall regional drought had eased. Referring to the four climate factors, the annual average temperature rose, the annual average precipitation was essentially unchanged, while relative humidity and sunshine duration decreased. Also, temperature and relative humidity had a remarkable correlation with VCI, which were the main factors affecting the drought.