Interpolation strategies for calibration of the Soil
Moisture and Ocean Salinity (SMOS) mission of the European
Space Agency are tested and compared. Calibration strategy (how
and how often) is critical in achieving the required performance
of any instrument, but it is even more important in very complex
instruments such as the new family of synthetic aperture
interferometric radiometers and, in particular, in the Microwave
Imaging Radiometer by Aperture Synthesis instrument aboard
the SMOS miss...
Interpolation strategies for calibration of the Soil
Moisture and Ocean Salinity (SMOS) mission of the European
Space Agency are tested and compared. Calibration strategy (how
and how often) is critical in achieving the required performance
of any instrument, but it is even more important in very complex
instruments such as the new family of synthetic aperture
interferometric radiometers and, in particular, in the Microwave
Imaging Radiometer by Aperture Synthesis instrument aboard
the SMOS mission. On one hand, frequent calibration reduces
the available observation time. On the other hand, the calibration
requirements for soil moisture applications are more relaxed than
those for ocean salinity, so the intercalibration time requirements
are very different. Since SMOS drifts are stationary, half-orbit
information is available to perform different interpolation strategies.
In this letter, these approaches are tested to estimate the
calibration parameters between consecutive calibrations. The average
root-mean-square phase error is then used to find the optimum
interpolation strategy and intercalibration time. On the
other side, in real-time instruments, the “future” calibration data
are not available at the time of taking the measurements, and
predictors are required to estimate the evolution of the calibration
parameters from past data only. For these systems, the extended
Kalman filter can be used. The intercalibration time in a real-time
instrument is evaluated, and the requirements and performances
are compared to offline instruments.
Citació
Ramos, I. [et al.]. Optimum intercalibration time in synthetic aperture interferometric radiometers: application to SMOS. "IEEE Geoscience and Remote Sensing Letters", 2012, vol. 9, núm. 4, p. 774-777.
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