title: 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.
authors.affiliation: Institute of Remote Sensing and Information Application, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Wang
authors.affiliation: Institute of Remote Sensing and Information Application, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China.
authors.forename: Jing-feng
authors.initials: JF
authors.lastname: Huang
authors.affiliation: Institute of Remote Sensing and Earth Sciences, Hangzhou Normal University, Hangzhou 311121, China.
authors.forename: Xiu-zhen
authors.initials: XZ
authors.lastname: Wang
authors.affiliation: Institute of Remote Sensing and Earth Sciences, Hangzhou Normal University, Hangzhou 311121, China.
authors.forename: Meng-ting
authors.initials: MT
authors.lastname: Jin
authors.affiliation: Institute of Remote Sensing and Information Application, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Zhou
authors.affiliation: Institute of Remote Sensing and Information Application, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China.
authors.forename: Qiao-ying
authors.initials: QY
authors.lastname: Guo
authors.affiliation: Institute of Remote Sensing and Information Application, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China.
authors.forename: Zhe-wen
authors.initials: ZW
authors.lastname: Zhao
authors.affiliation: Institute of Remote Sensing and Information Application, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China.
authors.forename: Wei-jiao
authors.initials: WJ
authors.lastname: Huang
authors.affiliation: Institute of Remote Sensing and Information Application, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China.
authors.forename: Yao
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Institute of Remote Sensing and Information Application, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China.
authors.forename: Xiao-dong
authors.initials: XD
authors.lastname: Song
mesh_terms: D000465:Algorithms; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D012275:Oryza / Q000033:anatomy & histology / Q000145:classification* / Q000254:growth & development*; D058998:Remote Sensing Technology / Q000295:instrumentation* / Q000379:methods; D015203:Reproducibility of Results; D012621:Seasons; D012680:Sensitivity and Specificity; D018531:Spacecraft / Q000295:instrumentation*; D018511:Systems Integration
keywords: HJ-1 CCD; Intercalibration; Landsat-8 OLI; Phenological parameters; Vegetation index