摘要
针对近年来干旱发生频繁的华北地区,通过利用2000-2009年MODIS数据和气象观测站降水资料,建立草地和农田距平植被指数(AVI)与不同时间尺度标准化降水指数(SPI)之间的相关统计模型,比较AVI和距平水分指数(AWI)对干旱响应的敏感性。结果表明:(1)植被生长季AVI与不同时间尺度SPI的相关关系不同。草地AVI与1个月尺度的SPI(即1-SPI)相关系数较低,而与3-SPI相关最显著;而农田区AVI与SPI的相关性较低,总体上农田AVI与3-SPI的相关性较高;(2)AWI与AVI类似,也对SPI存在时滞响应,均与3-SPI有着极显著的相关关系,并且在干旱发生较严重的6～8月份AWI与3-SPI的相关性好于AVI与3-SPI的相关性;(3)运用AWI反演的华北地区2009年夏季干旱分布图较好地反映了旱情的时空分布,与相关气象资料结果相符合。
Drought occurred frequently in recent years in north China. In this study, MODO9A1,8-day surface reflectance derived from MODIS （moderate-resolution imaging spectroradiometer）images provided by NASA and monthly precipitation data from ground observations obtained by China Meteorological Data Sharing Service System, which were used to study temporal responses of MODIS-derived drought index to climatic factors in north China. Anomaly Vegetation Index（AVl） was computed from the time series data of NDVI （based on infrared and near in- frared bands） and Anomaly Water Index（AWl） was calculated from NDWI （based on near infrared and short infra- red wave bands） of MODIS. Given the consequences and pervasiveness of drought, it is important to assess the specialized indices that were used to assess drought sensitivity. The standardized precipitation index （SPI） has sev- eral characteristics that are an improvement in previous indices. In this paper, 1 -SPI, 2 -SPI, 3 -SPI, 6 -SPI and 12 - SPI were calculated. The correlations and lag relationships between AVI from April to October （ the grow- ing season） during 2000 to 2009 and the multiple-time scale SPI in north China grassland and cropland sites were investigated based on MODIS and climate data. Besides, the relations between AVI and AWl in different periods were also analyzed. According to the sensitivity analysis of the response of AVI and AWl to drought, summer drought from June to September in 2009 in north China were monitored and analyzed by AWl. The results show： （ 1 ） the correlations are different between AVI and SPI at different time scales during vegetation growing seasons. For the grassland, the correlations are insignificant between AVI and 1 - SPI, but significant between AVI and 3 - SPI. However, the correlation is lower between AVI and SPI for cropland than that for grassland. In general, the correlation is higher between AVI and 3 -SPI for cropland. （2） Similarly to AVI, AWl shows lag response to SPI, and has better correlation with 3 - SPI. The correlation between AWl and 3 - SPI is better than that between AVI and 3 -SPI during period from June to August when serious drought occurs. Therefore, AWl is more sensitive to drought than AVI in north China. （3） The time-series drought monitoring maps in north China for 2009 derived from AWl reflects the temporal and spatial dynamics of cal results. drought, which are consistent with the relevant meteorologi-
出处
《干旱区地理》
CSCD
北大核心
2012年第5期708-716,共9页
Arid Land Geography
基金
国家973计划资助项目(2009 CB723906)
国家863计划资助项目(2009AA122003)
