Effect of the ionosphere on P-band spaceborne SAR images

Radar backscatter measurements have proven to be positively correlated with above ground biomass and this correlation increases with the wavelength. Biomass retrieval algorithms have been developed for airborne P-band data collected over both boreal and tropical forests. Radar measurements are insensitive to cloud cover and can be operated during day and night. Hence a space-borne radar system, operating at low frequency, will permit the measurement, mapping, and understanding of these parameters with a spatial and temporal resolution suitable for modeling ecosystem processes at regional, continental, and global scales. Based on experience with airborne campaigns, a polarimetric low frequency or P-band SAR has been shown to be the most appropriate instrument to this purpose. One of the disadvantages of the P-band is that in this frequency band ionospheric distortion off the images is expected to be high. A quantitative estimation of the ionospheric influences on P-band imagery needs to be derived, which can lead to orbit parameters, which minimizes the impact of the ionosphere on biomass measurements.