CropWatch Cloud

Title Of The Magazine
Year Information	2013
KeyWord
Authors	Taifeng DONG , Bingfang WU, Jihua MENG
Intro	The fraction of photosynthetically active radiation absorbed by plant canopies (FPAR) is a key parameter for monitoring crop condition and estimating crop yield. In general, it is necessary to obtain top of canopy (TOC) reflectance from optical remote sensing data in digital number through the atmospheric correction procedure before retrieving FPAR. However, there are a few of uncertainties existed in the process of atmosphere correction and reduced the quality of TOC. This paper presents a vegetation index based on top-of-atmosphere (TOA) reflectance derived from HJ-1 CCD satellite for estimating directly crop FPAR. The vegetation index (HJVI) was designed based on the simulated results of a coupled radiative transfer model, including TOA reflectance and corresponded FPAR. The HJVI had taken the advantages of information in the green, the red and the near-infrared spectral domain aim at reducing the atmospheric effect and enhancing the sensitive to green vegetation. The HJVI was used to estimate soybean FPAR directly and validated using the field measurements. The result indicated that the inversion algorithm produced a good relationship between the prediction and measurement (R2 = 0.546, RMSE = 0.083) and the HJVI was potential for estimating FPAR based on the HJ-1 TOA reflectance directly.
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