1982—2014年中国沿海地区归一化植被指数(NDVI)变化及其对极端气候的响应

Variation of Normalized Difference Vegetation Index and its response to extreme climate in coastal China during 1982-2014

基于1982—2014年GIMMS NDVI3g数据集,分析中国沿海地区生长季归一化植被指数(NDVI)的时空变化特征,探讨NDVI对极端气温和极端降水年尺度和月尺度的响应特征。结果表明:中国沿海地区及其子区域NDVI均呈上升趋势,且该趋势具有一定持续性;江南及其以南各子区域的NDVI高于江南以北,但长江三角洲、珠江三角洲等地区NDVI下降较明显,而江南以北沿海地区NDVI多呈上升趋势。NDVI在东北沿海西部、华北和黄淮沿海各子区域与极端气温暖指数(暖昼日数和日最高气温的极高值)多呈负相关,在其他沿海地区多呈正相关。NDVI与极端气温冷指数(冷昼日数和日最低气温的极低值)在整个沿海地区基本呈负相关,且对冷指数的响应具有一定滞后性;江淮(含)以南各子区域的NDVI与气温日较差多呈正相关,以北基本呈负相关。NDVI在黄淮以北与极端降水之间一般呈正相关,在黄淮(含)以南和东北沿海中东部地区多呈负相关,黄淮(含)以北各子区域的NDVI对极端降水的滞后效应较明显。

Based on GIMMS NDVI3g dataset,the spatial-temporal dynamics of Normalized Difference Vegetation Index(NDVI)during growing season in the coastal area of China from 1982 to 2014 was explored.Additionally,the response of NDVI to extreme temperature events and extreme precipitation events at annual as well as monthly scale was further estimated at the regional scale of meteorological stations.Results showed that NDVI in the coastal area of China and its sub-regions all presented an upward trend during the past 33 years,and the increasing tendency would continue in the future.NDVI in the sub-regions to south of Jiangnan(south of the Yangtze River)(inclusive)coastal area was much higher than that to north;however,a significant decreasing trend of NDVI during 1982-2014 was found in the Yangtze River delta and the Pearl River delta,which were both located in the southern coastal area,and a general increasing trend was detected in the sub-regions to north of Jiangnan coastal area.NDVI was negatively correlated with the warm extremes(warm days and maximum value of daily maximum temperature)in the west of Dongbei(northeast China)coastal area,and subregions of Huabei(north China)and Huanghuai(Huanghe and Huaihe river basins)coastal areas,but was showing a positive correlation in the other sub-region coastal areas.A negative correlation was found between NDVI and the cold extremes(cool days and minimum value of daily minimum temperature)in the coastal area of China,where vegetation growth showed a lagging effect to cold extremes.NDVI generally had positive correlation with diurnal temperature range(DTR)in the sub-regions to south of Jianghuai(Yangtze and Huaihe river basins(inclusive)coastal area but was negatively correlated with diurnal temperature range to north.There was a positive correlation between NDVI and extreme precipitation indices(maximum 1-day precipitation amounts and maximum 5-day precipitation amounts)in the subregions to north of Huanghuai coastal area,but a negative correlation in the sub-regions to south,as well as in the central east of Dongbei coastal area.Moreover,an obviously lagged correlation between NDVI and extreme precipitation indices was found in the sub-regions to north of Huanghuai coastal area.