Photometric and interferometric observations of recent SAR arc events

The photometric and interferometric observation of three SAR arc events, occurred on October 4/5, 1980 (1), May 8/9 (2) and October 20/21 (3), 1981, were made at the field station near Albany, New York. The maximum intensities of these arcs were 0.49, 0.70 and 2.0 kR respectively. The peak emission altitude determined by triangular method was 505 +- 46 km at the earlier stage of observation. The average temperatures measured within the arcs (1), (2) and (3) were 1349, 1697 and 1472 deg K, respectively, and the temperature enhancement within the arc was 100 deg K for (1) and (2) and 200 deg K for (3). These temperature enhancement exceeded those predicted by 2-dimensional model calculation. The present results showed that the temperature enhancement within the arcs is strongly correlated with the overall maximum intensity of the arcs. When the maximum intensity of the arcs reached about 400 R, the temperature within the arcs was variable, but the temperature enhancement within the arcs became almost always detectable. However, when the overall maximum intensity of the arcs reached about 2 kR, the temperature within the arcs was quite stable, and the temperature enhancement within the arcs was quite substantial. (Ishimitsu, A.)