The combined data set of polar mesospheric clouds (PMCs) from multiple SBUV instruments, which now extends for 38 years, demonstrates long-term variations with both periodic and trend characteristics. The periodic component of these variations appears as an anti-correlation between the level of solar activity, as characterized by solar Lyman alpha flux, and various indicators of PMC behavior (occurrence frequency, albedo, ice water content). This relationship was fairly distinct during the 1980s and 1990s, but has been considerably weaker during the 2000s. This has led to suggestions that forcing from additional sources, such as stratospheric warming caused by volcanic eruptions, may have enhanced the apparent periodic response at certain times.

Extending the SBUV PMC record through the most recent season (NH 2017) provides us with approximately 3½ solar cycles of data, which makes it possible to apply statistical techniques such as superposed epoch analysis (SEA) to these data. We will present the updated SBUV PMC data set, which now includes OMPS Nadir Profiler (NP) data, and describe the results of applying SEA to both Northern Hemisphere and Southern Hemisphere data.