光谱异同性和多尺度卫星雪盖差异分析——以MODIS和HJ-1B为例

Spectrum Similarities-Based Analysis of Spatial Difference of Snow Cover for Multi-Scale Satellite Data—a Case Study of MODIS and HJ-1BData

为了探索不同类型遥感传感器对地物反射光谱响应的异同和卫星遥感监测雪盖空间尺度的差异,收集了2007年—2013年冬春季川西北米亚罗地区、青海省祁连山区和新疆北疆地区各种积雪、植被和裸土反射光谱数据,经中分辨率成像光谱仪MODIS和环境与灾害监测预报小卫星HJ-1B传感器响应函数完成地基光谱到传感器可见光、近红外及短波红外通道反射率的转换。分析了新旧融雪、不同雪深及不同积雪覆盖下的反射光谱特征及不同传感器对地物反射光谱响应的异同性,并结合同期同区域影像分析了MODIS和HJ-1B积雪监测空间尺度的效果差异。结果表明,可见光波段范围内,各传感器对新雪和污雪反射光谱响应一致性很高;对裸土和矮株植被反射光谱响应程度较为一致;对其他类型积雪反射光谱响应程度有所不同,尤其是消融积雪和冻结积雪,反射光谱响应性差异很大;全雪覆盖下,深度不同的积雪NDSI值域相对稳定,不同传感器NDSI具有很好的趋势一致性;MODIS和HJ1BNDSI法监测积雪空间尺度差异明显,很好的解释了混合像元存在的成因。

Vegetation and bare soil were collected in the areas of Miyaluo district in northwest of Sichuan province ,the Qilian Mountains in Qinghai province and northern areas of Xinjiang during the years of 2007 and 2013 .Then these data were converted to spectral reflectance by applying sensor response function of MODIS and HJ-1B respectively within the range of visible light , near-infrared and shortwave infrared .Comprehensive analysis was made on spectral characteristics and reflectivity similarities and differences of different sensors between old and new snowmelt ,under the condition of different snow depth and different snow cover .The conclusions can be drawn .That is ,there exists high consistency of spectral response between new snow and dirty snow for each sensor in the visible wavelength range ,also it is true for bare soil and low vegetation .However ,low consis-tency happens to other types of snow ;especially snowmelt and frozen snow .The range of NDSI is relatively stable under the condition of different snow depth for full snow cover and the trend of NDSI shows great consistency for different sensors ;NDSI threshold method for monitoring snow by using MODIS and HJ-1B data showed very obvious difference in spatial scales ,which is a reasonable explanation of the existence of mixed pixels .