遥感手段及气象干旱指数在新疆干旱监测过程中的应用

Comparison of the Vegetation Condition Index and Meteorological Drought Indices in Drought Monitoring of Xinjiang, China

利用由国家气象中心提供的新疆50个气象测站2003—2010年逐日降水、气温资料,结合中国科学院计算机网络信息中心国际科学数据镜像网站MODIS合成影像逐月归一化植被覆盖指数及国家自然科学基金委员会"中国西部环境与生态科学数据中心"提供的2005年全国土地利用类型数据,对比分析了遥感手段及气象干旱指数在新疆干旱监测工作中的应用,分析了新疆物侯期植被状态指数及气象干旱指数间的相关性,进一步探讨新疆植被生长状况与气象干旱的发生、发展情况。植被长势对降水、气温等气候因素变化的响应存在一定滞后性,生长季气象干旱指数与植被状态指数之间的相关性在时间尺度上同样存在滞后效应。植被状况指数(Vegetation Condition Index,VCI)与标准化降水指数(Standardized Precipitation Index,SPI)及标准化蒸散发指数(Standardized Precipitation Evapotranspiration Index,SPEI)相关性较好,其中SPEI综合考虑了降水、气温对干湿变化的影响。时间尺度上,耕地类型区、林地类型区VCI与SPI24、SPEI24相关性最好,草地类型区VCI与基于短时间尺度(3个月、6个月)的SPI、SPEI相关性最好;空间尺度上,SPEI24与VCI相关程度最高。总体上,全疆基于24个月时间尺度SPEI与基于植被状况指数的干旱监测效果相关性较好。文章旨在为今后新疆干旱监测工作及进一步探讨植被长势对干湿事件的响应提供重要理论依据,为合理有效地安排农作物生产及植被保护、植被恢复工作提供一定的理论指导。

The performance of vegetation condition index and meteorological drought indices in drought monitoring in different land cover patterns during growing season in Xinjiang have been compared and analyzed in this study. Standardized precipitation index (SPI) and standardized precipitation evapotranspiration (SPEI) index based on different time scales precipitation have been calculated based on daily precipitation, daily average temperature, daily maximum temperature and daily minimum temperature data from 50 meteorological stations. Vegetation condition index have been done with the processing of pixels using Arcgis and Matlab based on monthly NDVI data which has been provided by International Scientific & Technical Data Mirror Site, Computer Network Information Center, Chinese Academy of Sciences. And land cover patterns of 2005 is provided by Cold and Arid Regions Science Data Center at Lanzhou. Results showed that there is a time lag between the vegetation and precipitation, temperature value. And also between the VCI and meteorological droughts. VCI has a good correlation with SPI and SPEI, and the calculation of SPEI take precipitation and temperature into consideration. On the time scale, the relationship between SPEI3, SPEI6 and the vegetation growth of grasslands are best, and the relationship between SPEI12, SPEI24 and forest lands, cultivated lands are best. The correlation between SPEI24 and VCI is best in the spatial scale. Results of this study can provide an important theoretical basis for drought monitoring and vegetation responses to wet and dry events in the future, and it can also provide certain theoretical guidance to vegetation growth and reasonable and effective arrangement of crop production and protection.