Latitude variations in light scattered from polar mesospheric clouds

A middle ultraviolet imager over the northern and southern polar regions ha s measured the scattered intensities of polar mesospheric clouds (PMC) duri ng the austral summer of 1997-98 and the arctic summer of 1999. The intensi ties, corrected for solar zenith angle, are those at the peak in the PMC ra diance profiles for a waveband of 235-263 nm. The peak radiance averaged 12 .0 +/-1.0 mega-Rayleighs (MR) for 13 passes over tile south polar region, w here the scattering angle was similar to 111 degrees. The peak radiance ave raged 11.4 +/-7.6 MR for 12 passes over the north polar region, where the s cattering angle was similar to 48 degrees. The PMC intensities increased wi th increasing latitude in both tile north and the south, but the rate of in crease was twice as fast in the south (0.60 MR/degrees latitude) as in the north (0.32 MR/degrees latitude).