Title :
A RADARSAT-2 Quad-Polarized Time Series for Monitoring Crop and Soil Conditions in Barrax, Spain
Author :
Moran, M. Susan ; Alonso, Luis ; Moreno, Jose F. ; Mateo, Maria Pilar Cendrero ; De la Cruz, D. Fernando ; Montoro, Amelia
Author_Institution :
USDA Southwest Watershed Res. Center, Tucson, AZ, USA
fDate :
4/1/2012 12:00:00 AM
Abstract :
An analysis of the sensitivity of synthetic aperture radar (SAR) backscatter (σo) to crop and soil conditions was conducted using 57 RADARSAT-2 C-band quad-polarized SAR images acquired from April to September 2009 for large fields of wheat, barley, oat, corn, onion, and alfalfa in Barrax, Spain. Preliminary results showed that the cross-polarized σHVo was particularly useful for monitoring both crop and soil conditions and was the least sensitive to differences in beam incidence angle. The greatest separability of barley, corn, and onion occurred in spring after the barley had been harvested or in the narrow time window associated with grain crop heading when corn and onion were still immature. The time series of σo offered reliable information about crop growth stage, such as jointing and heading in grain crops and leaf growth and reproduction in corn and onion. There was a positive correlation between σo and the Normalized Difference Vegetation Index for onion and corn but not for all crops, and the impact of view direction and incidence angle on the time series was minimal compared to the signal response to crop and soil conditions. Related to planning for future C-band SAR missions, we found that quad-polarization with image acquisition frequency from 3-6 days was best suited for distinguishing crop types and for monitoring crop phenology, single- or dual-polarization with an acquisition frequency of 3-6 days was sufficient for mapping crop green biomass, and single- or dual-polarization with daily image acquisition was necessary to capture rapid changes in soil moisture condition.
Keywords :
crops; geophysical image processing; phenology; radar polarimetry; soil; synthetic aperture radar; time series; vegetation mapping; Barrax; Normalized Difference Vegetation Index; RADARSAT-2 C-band quadpolarized SAR images; RADARSAT-2 quadpolarized time series; Spain; alfalfa; barley; beam incidence angle; corn; crop green biomass; crop growth stage; crop phenology; crop types; daily image acquisition; dual-polarization; future C-band SAR missions; grain crop; image acquisition frequency; incidence angle; leaf growth; narrow time window; oat; onion; positive correlation; signal response; soil moisture condition; synthetic aperture radar backscatter; view direction; wheat; Agriculture; Backscatter; Satellites; Soil; Synthetic aperture radar; Time series analysis; Barley; Radarsat; Rapideye; Sentinel-1; corn; onion; phenology;
Journal_Title :
Geoscience and Remote Sensing, IEEE Transactions on
DOI :
10.1109/TGRS.2011.2166080