کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
6347030 | 1621260 | 2014 | 11 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Comparison between SMOS Vegetation Optical Depth products and MODIS vegetation indices over crop zones of the USA
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موضوعات مرتبط
مهندسی و علوم پایه
علوم زمین و سیارات
کامپیوتر در علوم زمین
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
The Soil Moisture and Ocean Salinity (SMOS) mission provides multi-angular, dual-polarised brightness temperatures at 1.4 GHz, from which global soil moisture and vegetation optical depth (Ï) products are retrieved. This paper presents a study of SMOS' Ï product in 2010 and 2011 for crop zones of the USA. Retrieved Ï values for 504 crop nodes were compared to optical/IR vegetation indices from the MODIS (Moderate Resolution Imaging Spectroradiometer) satellite sensor, including the Normalised Difference Vegetation Index (NDVI), Enhanced Vegetation Index (EVI), Leaf Area Index (LAI), and a Normalised Difference Water Index (NDWI) product. Ï values were observed to increase during the growing season and decrease during senescence in these areas, as did MODIS vegetation indices. SMOS' Ï values generally peaked later than MODIS LAI values, with an estimated time difference of about 19 days. A linear regression between Ï and the MODIS products was carried out for each node and values of the determination coefficient, R2, slope, bâ² and intercept, bâ³ were found. The average R2 value varied from 0.32 to 0.35 for the different vegetation indices. The linear regression between LAI and Ï produced an average slope of bâ²Â = 0.06, and an average intercept of bâ³Â = 0.14. The effects of crop fraction and dominant crop type were investigated and crop fraction was found to have a low effect on R2 values. R2values appeared to be lower for wheat and hay and higher for corn. bâ² and bâ³ values had higher standard deviations for wheat but were generally close to the mean values for corn, soybean and hay.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Remote Sensing of Environment - Volume 140, January 2014, Pages 396-406
Journal: Remote Sensing of Environment - Volume 140, January 2014, Pages 396-406
نویسندگان
Heather Lawrence, Jean-Pierre Wigneron, Philippe Richaume, Nathalie Novello, Jennifer Grant, Arnaud Mialon, Ahmad Al Bitar, Olivier Merlin, Dominique Guyon, Delphine Leroux, Simone Bircher, Yann Kerr,