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Retrieval of transplantation date (TP) using RISAT-1 medium resolution SCANSAR data for operational pre-harvest crop monitoring has been demonstrated. The methodology used 3-date HH-polarized RISAT data capturing the onset of transplantation (minimal backscatter) and rises as crop grows, for the country scale within 2–4 days of planting and was found to closely agree to ground conditions. Transplantation date ranged from June in north to October in Tamil Nadu. This variation significantly reduced to a month in the summer paddy due to irrigation. Transplantation patterns were different in both the seasons' paddy. Validation exercise for TP in four major states confirmed the feasibility of retrieval datasets for transplantation date monitoring as it matched within 2–4 days in north, south India and MP but 6–8 days in Assam. The technique has reached a level of maturity and is routinely used for monitoring the transplantation date by the Department of Agriculture, India. [ABSTRACT FROM AUTHOR]

A polarimetric radar system measures the complete scattering matrix of a target in the backscattered field that includes magnitudes of linearly polarized scattering amplitudes and the co- polarised and cross-polarised phase angles. Apart from backscattering intensity, the co-polarization phase difference (CPD) calculated from polarimetric synthetic aperture radar (SAR) data produces important information about target physical, geometrical and dielectric properties. In the present work, the distribution of CPD in C-band polarimetric SAR data corresponding to major kharif and rabi crops (denoting the monsoon and the winter season) and other land cover features have been studied over Central State Farm, Hisar, Haryana. The probability density functions (PDF) of CPD have been compared with dominant scattering contributions from these targets as obtained from polarimetric target decompositions. The results show that crops and other land cover features show characteristic CPD distributions, which relates well with crop physical and geometrical properties. An intuition of the rate of growth and plant vigour is indicative from the temporal PDF pattern. [ABSTRACT FROM AUTHOR]

To develop an operational methodology for estimating soil moisture and crop biophysical parameters and to generate a crop cover map, backscattering signatures of vegetation canopies are investigated using multitemporal Radarsat synthetic aperture radar (SAR) data over a predominantly cotton-growing area in India during low to peak crop growth stage. A simple parameterization of the water-cloud model with volumetric soil moisture content (mv) and leaf area index (LAI) is used to simulate the microwave backscattering coefficient (σ0), as it is found to be a good candidate for operational purposes as demonstrated by several workers in past. The influence of crop height (H), LAI, and mv on σ0 is investigated during peak crop growth stage. A linear relationship between LAI and crop height is derived semiempirically, and a linear zone is chosen for analysis during the peak crop-growing stage. Estimation of average volume fraction of leaves (&Vsline;l) and attenuation factor (L) by two different approaches is discussed: 1) using linear relationship between LAI versus crop height and 2) from the water-cloud model parameter (κ) estimation by iterative minimum least square error approach. It is observed that model-estimated parameters agree well with the measured values within an acceptable error limit. At tower soil moisture, mv ≅0.02 (cm³ · cm-3), the dynamic range of &cigma;0 is found to be about +5 dB for 0-70 cm of crop height but monotonously decreases to null at a transition point, having mv ≈ 0.38 (cm³ · cm-3). A positive correlation is found between backscattering coefficient and crop height fill this transition point but shows a negative correlation beyond that, signifying the predominant attenuation by vegetation over soil. [ABSTRACT FROM AUTHOR]