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Journal of Zhejiang University SCIENCE B

ISSN 1673-1581(Print), 1862-1783(Online), Monthly

Estimation of rice phenology date using integrated HJ-1 CCD and Landsat-8 OLI vegetation indices time-series images

Abstract: Accurate estimation of rice phenology is of critical importance for agricultural practices and studies. However, the accuracy of phenological parameters extracted by remote sensing data cannot be guaranteed because of the influence of climate, e.g. the monsoon season, and limited available remote sensing data. In this study, we integrate the data of HJ-1 CCD and Landsat-8 operational land imager (OLI) by using the ordinary least-squares (OLS), and construct higher temporal resolution vegetation indices (VIs) time-series data to extract the phenological parameters of single-cropped rice. Two widely used VIs, namely the normalized difference vegetation index (NDVI) and 2-band enhanced vegetation index (EVI2), were adopted to minimize the influence of environmental factors and the intrinsic difference between the two sensors. Savitzky-Golay (S-G) filters were applied to construct continuous VI profiles per pixel. The results showed that, compared with NDVI, EVI2 was more stable and comparable between the two sensors. Compared with the observed phenological data of the single-cropped rice, the integrated VI time-series had a relatively low root mean square error (RMSE), and EVI2 showed higher accuracy compared with NDVI. We also demonstrate the application of phenology extraction of the single-cropped rice in a spatial scale in the study area. While the work is of general value, it can also be extrapolated to other regions where qualified remote sensing data are the bottleneck but where complementary data are occasionally available.

Key words: Phenological parameters, Intercalibration, Vegetation index, HJ-1 CCD, Landsat-8 OLI

Chinese Summary  <20> 基于环境减灾卫星及Landsat-8卫星的植被指数时间序列的水稻物候期提取研究

目的:鉴于中国南方地区单季稻种植区在关键生育期较难获得清晰影像的情况,利用相互校准方法并结合HJ-1 CCD和Landsat-8 OLI传感器,生成时间分辨率更高的植被指数时间序列数据,并比较不同植被指数在提取水稻物候期中的差异。
创新点:本文通过传感器相互校准获得了具有更高时间分辨率的植被指数时间序列数据,同时研究了不同植被指数在提取水稻物候期中的有效性,从而提高了水稻物候期提取的精度。
方法:利用最小二乘法对HJ-1 CCD和Landsat-8 OLI传感器提取的植被指数(EVI2和NDVI)进行相互校准,验证了不同传感器可互补使用;利用一致性分析方法,对比不同植被指数在提取单季稻物候期中的有效性;通过极值法和最大斜率法提取研究区单季稻的移栽期、抽穗期和成熟期;将利用两传感器相结合形成的新植被指数时间序列数据得到的水稻物候期提取结果,与用单一传感器得到结果进行对比,分析水稻物候期提取精度。
结论:基于环境减灾卫星及Landsat-8卫星融合后得到的植被指数时间序列数据可以有效地提高南方单季稻物候期提取的精度,EVI2的提取效果优于NDVI,极值法和最大斜率法结合提取的单季稻物候期结果与野外调查及农气站统计结果较为吻合,可以很好地应用于实际业务中。

关键词组:物候提取;相互校准;植被指数;HJ-1 CCD;Landsat-8 OLI


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DOI:

10.1631/jzus.B1500087

CLC number:

S511

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On-line Access:

2015-10-03

Received:

2015-04-15

Revision Accepted:

2015-09-14

Crosschecked:

2015-09-17

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