An investigation on microwave transmissivity at frequencies of 18.7 and 36.5 GHz for diverse forest types during snow season  

作　　者：Wang Guangrui Li Xiaofeng Chen Xiuxue Jiang Tao Zheng Xingming Wei Yanlin Wan Xiangkun Wang Jian 

机构地区：[1]Northeast Institute of Geography and Agroecology,Chinese Academy of Sciences,Changchun,People’s Republic of China [2]College of Resources and Environment,University of Chinese Academy of Sciences,Beijing,People’s Republic of China [3]Changchun Jingyuetan Remote Sensing Experiment Station,Chinese Academy of Sciences,Changchun,People’s Republic of China [4]School of Statistics,Dongbei University of Finance and Economics,Dalian,People’s Republic of China

出　　处：《International Journal of Digital Earth》2021年第10期1354-1379,共26页国际数字地球学报（英文）

基　　金：supported by National Natural Science Foundation of China:[Grant Number 41771400];National Natural Science Foundation of China:[Grant Number 41871248];Science and Technology Basic Resources Investigation Program of China‘Investigation on snow characteristics and their distribution in China’[Grant Number 2017FY100500].

摘　　要：Forests have invariably been considered as an obstacle in retrieving land surface parameters from spaceborne passive microwave brightness temperature(T_(B))observations.For quantifying the effect of forests on microwave signals,several models have been developed.However,these models rarely reveal the dependence of microwave radiation on forest types,which can hardly meet the needs of high-accuracy retrieval of terrestrial parameters in forested regions.A ground-based microwave radiometric observation experiment was designed to investigate the dependence of microwave radiation on frequency,polarization,and forest type.Downward TB at 18.7-and 36.5-GHz for horizontal-and vertical-polarization from the forest canopy was measured at 14 sample plots in Northeast China,along with snowpack and forest structural parameters.By providing fits to experimental data,new empirical transmissivity models for three forest types were developed,as a function of woody stem volume and depending on the frequency/polarization.The proposed models give diverse asymptotic transmissivity saturation levels and the corresponding saturation point of woody stem volume for different forest types.Root-mean-square error results between T_(B) simulations and Advanced Microwave Scanning Radiometer-2 observations are approximately 3-6 K.This study provides an experimental and theoretical reference for further development of inversion models for snow parameters in forested areas.

关 键 词：Forest transmissivity SNOW woody stem volume microwave radiometry HUT 

分 类 号：S71[农业科学—林学]