Ionospheric irregularities and their potential impact on synthetic aperture radars

Accumulating data are making it increasingly evident that major plasma irregularities populate substantial portions of the ionosphere. In contrast with these findings, satellite-borne synthetic aperture radar (SAR) systems tacitly assume that the ionosphere is uniformly layered and unchanging under the orbiting SAR. Analysis of plasma irregularity structures measured directly on the S3-4 satellite shows that this assumption is readily violated near the nighttime equator during the occurrence of spread F and at high-latitudes on a nearly 24-hour basis. The irregularities can be very intense, covering scale sizes from meters to hundreds of kilometers. Associated along-track phase path calculations point to a potentially serious problem in SAR imaging integrity in restricted ionospheric space-time domains.