准噶尔盆地地表反照率时空变化特征及其影响因素分析

Spatio-temporal variation characteristics of surface albedo and analysis of influential factors in the Junggar Basin

地表反照率变化影响地表辐射收支与能量平衡,从而对区域和全球气候产生影响。以准噶尔盆地为研究对象,利用MODIS卫星遥感数据产品MOD09A1反演地表短波反照率,结合气象数据和植被指数分析准噶尔盆地2001—2018年荒漠草地地表反照率时空变化特征及其影响因素。结果表明:准噶尔盆地地表反照率空间分布地域差异明显,地表反照率年均值为0.303,整体呈东北高、西南低的特点;其年际变化速率呈减少趋势,平均每年为1.4×10^(-4),减少面积约占总面积的52.8%;四季空间分布变化明显,春、夏、秋三季空间分布相似,冬季值最高(0.551),夏季最低(0.203)。准噶尔盆地东北缘的阿尔泰山地表反照率年内变化较为剧烈;生长季归一化植被指数(NDVI)值大小为:夏季>秋季>春季。准噶尔盆地整体地表反照率与NDVI呈负相关,大部分区域与平均气温呈负相关,与降水呈正相关,且相关性大小依次为气温>NDVI>降水。MODIS反演结果与地面实测值之间存在显著的相关性(R^(2)=0.8908,P<0.01),均方根误差为0.014。为了解准噶尔盆地陆面特征,客观评价全球气候变化下干旱区陆面变化及其正负反馈响应机制提供一定的理论依据。

Surface albedo influences the balance between surface radiation and energy,affecting regional and global climates.The Moderate Resolution Imaging Spectroradiometer remote sensing data product MOD09A1 was used to retrieve surface short-wave albedo for the Junggar Basin.This was used to analyze the spatio-temporal variation and factors influencing the surface albedo of the desert grassland in the Junggar Basin during the period 2001-2018,based on meteorological data and the vegetation index.The results revealed evident differences in the spatial distribution of surface albedo across the study region,with an annual mean value of 0.303,high values in the northeast region and low values in the southwest region.The interannual variation of surface albedo showed a decreasing trend,with an average value of 1.4×10^(−4).The decreased area accounted for approximately 52.8% of the total area,and its spatial distribution significantly varied across the four seasons.The spatial distributions in spring,summer,and autumn were similar,with the highest(0.551)and lowest(0.203)values observed in winter and summer,respectively.The surface albedo of the Altai Mountains in the northeast margin of the Junggar Basin drastically varied during the year:The normalized difference vegetation index(NDVI)value in the growing season was high in spring,significantly higher in autumn,and highest in summer.The surface albedo was negatively correlated with the NDVI and average temperature and positively correlated with precipitation in the majority of the study region.The correlation was as follows:Temperature>NDVI>precipitation.Further,there was a significant correlation between the retrieved results and measured values(R^(2)=0.8908,P<0.01),and the root mean square error was 0.014.This study provides a theoretical basis for understanding the land-surface characteristics of the Junggar Basin in Northern Xinjiang,and it objectively evaluated the surface changes in arid regions and determined the positive and negative feedback response mechanisms under global climate change.