基于AMSR-E的全球陆表被动微波发射率数据集

Global Land Surface Emissivity Dataset based on AMSR-E Observations

地表微波发射率表征了地物向外发射微波辐射的能力,星载被动微波发射率估算可在宏观、大尺度上对陆表微波辐射进行整体表达,是被动微波地表参数定量反演中重要基础数据,也是在大尺度上获取陆表微波辐射特征的一种途径。本数据集利用搭载在Aqua卫星上的高级微波扫描辐射计（AMSR-E）和中分辨率成像光谱仪（MODIS）的同步观测特点,采用MODIS的地表温度和大气水汽产品数据作为输入,基于考虑大气影响的发射率估算模型,生产了全球晴空条件下AMSR-E传感器运行期间（2002年6月～2011年10月）的陆表多通道双极化微波瞬时发射率。通过产品低频无线电信号影响、数据间比对、分布统计、不同地表覆盖条件的发射率特征、频率依赖和相关性研究等开展验证性分析,结果表明：瞬时发射率的动态大、细节表达丰富,月内日变化标准差在0.02以内,其时空变化、频率依赖和相关性等符合微波理论分析和自然物理过程理解。此套数据集还包括AMSR-E全生命周期的全球陆表逐日、侯、旬、半月及月产品,可用于开展星载被动微波遥感模拟、陆面模型以及陆表温度、积雪、大气降水/水汽/可降水量等反演研究。

Earth surface microwave emissivity,representing the capacity of the earth＇s surface emitting microwave radiation outwards,is one of the key physical quantities of microwave radiometric characteristics for earthsurface.Satellite-borne passive microwave emissivity shows an overall and macroscopic expression of the surface microwave radiation on a large scale.It is important basic data for empirical parameterization acquisition in the geophysical parameters quantitative inversion from passive microwave observations,and also an approach of understanding the land surface microwave radiation on a large scale.Considering the synchronous observation characteristic of the Advanced Microwave Scanning Radiometer（AMSR-E）and Moderate Resolution Imaging Spectroradiometer（MODIS）mounted on the Aqua satellite,taking surface temperature and atmospheric water vapor data from MODIS as input data,this data set produced multichannel microwave instantaneous emissivity through the emissivity estimation model during the operating cycle（June 2002～October 2011）of AMSR-E sensor under the global clear-sky condition.The results obtained from inter-comparison,statistical analysis and the validation analysis from the frequency dependence and the correlation under different land covers indicate that,the dynamic range of instantaneous emissivity is larger,the monthly diurnal standard deviationare within 0.02,and the Radio Frequency Interference analysis,spatial and temporal variation,frequency dependence and correlation are in consistence with the understanding of natural physical geography process and microwave emission model understanding.The dataset,which includes daily,five-day,ten-day,semi-monthly and monthly global land surface products within the AMSR-E full life span,may be used in the inversion of satellite borne passive microwave remote sensing simulation,land surface model,land surface temperature,snow parameters,precipitation,water vapor and perceptible water content etc.