PALSAR Polarimetric accuracy and stability evaluated for three years Amazon data
Masanobu Shimada(1) and Masato Ohki(1)
(1) Japan Aerospace Exploration Agency, Earth Observation Research Centre, Sengen 2-1-1 Tsukuba Ibaraki, Japan
PALSAR polarimetry mode expands the earth observation capability in use of polarization information. This new mode became first operational in PALSAR and thus it fascinates the researchers than the conventional SAR's, which is flying on the polar orbiting satellites, i.e., Envisat, Radarsat, ERS-2, etc. Although the hardware requires more weight and complexity at the operation, i.e., the double scale of PRFs and thus the reduced imaging swath limits the incidence angle (9.9 degrees to 27 degrees), the high stability of the polarimetry mode between HH and VV channel provides a big potential for demonstrating the extraction of the geophysical parameters.
Since the calibration is conducted through heavy discussions through the international science team meetings, the provided calibration sites worldwide noticed the high sensitivity of the PALSAR on the latitude and the ionospheric stability. The calibration parameters, i.e., distortional matrices of the transmission and reception, are finally calculated using the corner reflector deployed in the Amazon area over the almost zero geomagnetic latitude where the geomagnetic intensity in the radar line of site component, thus the Faraday rotation component, is minimized when the PALSAR is flying in the ascending orbit.
After that, we have been deploying two corner reflectors for ascending and two for descending orbits at the test site of Rio Branco, Amazon, collaborating with the Brazilian Geographical Institute (IGBP). We have integrated the number of the calibration points. Using these corner reflectors as well as the Amazon rainforest data we evaluated and summarized the stability and the accuracy of the PALSAR polarimetric modes and interaction between the SAR and the ionosphere in this presentation.