Comparing land surface phenology of major European crops as derived from SAR and multispectral data of Sentinel-1 and-2

REMOTE SENSING OF ENVIRONMENT

卷:253

Article

Meroni, Michele¹  d'Andrimont, Raphael¹  Vrieling, Anton²  Fasbender, Dominique¹  Lemoine, Guido¹  Rembold, Felix¹  Seguini, Lorenzo¹  Verhegghen, Astrid¹ 

[1] European Commiss, Joint Res Ctr JRC, Via E Fermi 2749, I-21027 Ispra, VA, Italy

[2] Univ Twente, Fac Geoinformat Sci & Earth Observat, POB 217, NL-7500 AE Enschede, Netherlands

关键词: Satellite image time series;    Land surface phenology;    Agriculture;    Crop phenology;    Sentinel-1;    Sentinel-2;    LUCAS survey;    DWD ground phenological observations;    Europe;   

DOI  :  10.1016/j.rse.2020.112232

来源: Elsevier

【 摘 要 】

The frequent acquisitions of fine spatial resolution imagery (10 m) offered by recent multispectral satellite missions, including Sentinel-2, can resolve single agricultural fields and thus provide crop-specific phenology metrics, a crucial information for crop monitoring. However, effective phenology retrieval may still be hampered by significant cloud cover. Synthetic aperture radar (SAR) observations are not restricted by weather conditions, and Sentinel-1 thus ensures more frequent observations of the land surface. However, these data have not been systematically exploited for phenology retrieval so far. In this study, we extracted crop-specific land surface phenology (LSP) from Sentinel-1 and Sentinel-2 of major European crops (common and durum wheat, barley, maize, oats, rape and turnip rape, sugar beet, sunflower, and dry pulses) using ground-truth information from the Copernicus module of the Land Use/Cover Area frame statistical Survey (LUCAS) of 2018. We consistently used a single model-fit approach to retrieve LSP metrics on temporal profiles of CR (Cross Ratio, the ratio of the backscattering coefficient VH/VV from Sentinel-1) and NDVI (Normalized Difference Vegetation Index from Sentinel-2). Our analysis revealed that LSP retrievals from Sentinel-1 are comparable to those of Sentinel-2, particularly for winter crops. The start of season (SOS) timings, as derived from Sentinel-1 and -2, are significantly correlated (average r of 0.78 for winter and 0.46 for summer crops). The correlation is lower for end of season retrievals (EOS, r of 0.62 and 0.34). Agreement between LSP derived from Sentinel-1 and -2 varies among crop types, ranging from r = 0.89 and mean absolute error MAE = 10 days (SOS of dry pulses) to r = 0.15 and MAE = 53 days (EOS of sugar beet). Observed deviations revealed that Sentinel-1 and -2 LSP retrievals can be complementary; for example for winter crops we found that SAR detected the start of the spring growth while multispectral data is sensitive to the vegetative growth before and during winter. To test if our results correspond reasonably to in-situ data, we compared average crop-specific LSP for Germany to average phenology from ground phenological observations of 2018 gathered from the German Meteorological Service (DWD). Our study demonstrated that both Sentinel-1 and -2 can provide relevant and at times complementary LSP information at field- and crop-level.

【 授权许可】

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