基于Hyperion高光谱数据的植被冠层含水量反演

Estimation of Vegetation Canopy Water Content Using Hyperion Hyperspectral Data

植被冠层含水量广泛应用于农业、生态和水文等研究中。本文基于PROSAIL模型,建立了利用Hyperion高光谱数据定量反演植被冠层含水量的模型。首先,PROSAIL模型模拟植被冠层反射特征表明,970nm水吸收带右侧曲线(980～1 070nm)一阶导数D980～1 070与冠层含水量关系密切,决定系数达0.96。基于此,利用Hyperion数据的983,993,1 003,1 013,1 023,1 033,1 043,1 053,1 063nm共9个波段计算D980～1 070,并利用所建模型反演植被冠层含水量。最后,利用黑河流域盈科绿洲的实测数据对反演结果进行了验证,其平均相对误差为12.5%,均方根误差在0.1kg·m-2内,结果表明该模型可靠。该研究可以为大范围获取植被含水量信息提供有效方法。

Vegetation canopy water content （VCWC） has widespread utility in agriculture, ecology and hydrology. Based on the PROSAIL model, a novel model for quantitative inversion of vegetation canopy water content using Hyperion hyperspectral data was explored. Firstly, characteristics of vegetation canopy reflection were investigated with the PROSAIL radiative transfer model, and it was showed that the first derivative at the right slope （980-1 070 nm） of the 970 nm water absorption feature （D980-1070） was closely related to VCWC, and determination coefficient reached to 0. 96. Then, bands 983, 993, 1 003, 1 013, 1 023, 1 033, 1 043, 1 053 and 1 063 nm of Hyperion data were selected to calculate D980-1070, and VCWC was estimated using the proposed method. Finally, the retrieval result was verified using field measured data in Yingke oasis of the Heihe basin. It indicated that the mean relative error was 12. 5%, RMSE was within 0. 1 kg.m-2 and the proposed model was practical and re- liable. This study provides a more efficient way for obtaining VCWC of large area.