Effect of atmosphere on GEOSAR focusing performance

Abstract

Due to high attitude and long synthetic aperture time of geosynchronous synthetic aperture radar (GEOSAR), working in the L band, ionosphere and troposphere severely impact the focusing performance of this radar. In this study, considering the movement characteristics of GEOSAR, the range error model caused by the atmospheric refractive index based on non ‘stop-and-go’ assumption is inferred. Then, the echo signals under the influence of ionosphere and troposphere are deduced, respectively. Finally, the influences of ionosphere and troposphere on GEOSAR focusing performance are analysed and simulated. The simulated results validate that troposphere and ionosphere are the important factors that affect the imaging quality. The tropospheric effects are relatively small. The influence of ionosphere on imaging performance along range and azimuth is much greater, often resulting in image drift and azimuth resolution decline. Change of ionospheric total electron content is more intense, they lower the imaging quality.

Keywords

• radar imaging
• refractive index
• synthetic aperture radar
• geophysical image processing
• ionospheric electromagnetic wave propagation
• electromagnetic wave refraction
• azimuth resolution decline
• image drift
• echo signals
• non stop-and-go assumption
• long synthetic aperture time
• ionospheric total electron content
• tropospheric effects
• imaging quality
• geosar focusing performance
• atmospheric refractive index
• range error model
• geosynchronous synthetic aperture radar