Long term variations in the frequency of polar mesospheric clouds in the Northern Hemisphere from SBUV

摘要: [1] Earlier studies have indicated that there is a secular increase in the occurrence frequency of polar mesospheric clouds (PMC), along with an anti-correlation solar activity. The combined data records from Solar Backscatter Ultraviolet (SBUV and SBUV/2) instruments provide longest satellite record (28 years) PMC occurrence. This has been analyzed to determine long-term variation each three latitude bands (54°–64°N, 64°–74°N, 74°–82°N). analysis includes adjustment for changes local time measurement due orbital drift, take into account diurnal variations frequency. Multiple linear regression fits using activity show nearly doubles maximum minimum all bands. There ranging 7% per decade at 64°–74°N 20% 74°–82°N. These increases are significant 95% level 74°–82°N latitudes combined. We find lag half year (with uncertainty one year) between activity, consistent our previous findings albedo.