基于PROSAIL模型的毛竹林冠层含水量反演研究

A Study on Canopy Water Content Inversion of Phyllostachys edulis Forest Based on PROSAIL Model

冠层含水量(canopy water content, CWC)的定量反演有助于毛竹林干旱胁迫状况的监测,对其生产管理具有重要意义。以永安天宝岩的毛竹林为研究对象,采用PROSAIL模型,通过全局敏感性分析结合实地调查和相关文献确定模型的参数设置,然后建立含水量与冠层反射率的查找表(LUT),进而利用查找表联合反演等效水厚度(EWT)与叶面积指数(LAI)得到冠层含水量(CWC),最后基于Sentinel-2B影像实现区域冠层含水量的空间量化。结果表明,1)EWT主要影响1 100 nm以后的冠层反射率,对可见光区域冠层反射率几乎无影响;2)基于PROSAIL模型可有效反演毛竹林冠层含水量,其R^(2)=0.536,RMSE为0.059 kg/m^(2);3)研究区域毛竹林7月的冠层含水量主要分布于0.12~0.41 kg/m^(2)。研究为冠层含水量反演提供一种有效的反演方法,有助于毛竹林的野火预防和病虫害防治。

The quantitative inversion of canopy water content(CWC)is useful for monitoring the drought stress condition of Phyllostachys edulis forest and is important for its production management.This study used the PROSAIL model to determine the parameters of the model through global sensitivity analysis combined with field surveys and retrieving related literatures.Finally,the spatial quantification of regional canopy water content was achieved based on Sentinel-2B images.The results showed that 1)the equivalent water thickness mainly affected the canopy reflectance over 1100 nm,and had almost no effect on the canopy reflectance in the visible region.2)The canopy water content of P.edulis forest could be effectively inverted based on the PROSAIL model,with R 2 of 0.536 and RMSE of 0.059 kg/m^(2).3)The canopy water content of P.edulis forests in the study area in July was mainly distributed in the range of 0.12-0.41 kg/m^(2).The study provides an effective inversion method for canopy water content inversion,which is helpful for wildfire prevention and pest control in P.edulis forests.