Relationship between the summer mesopause and polar mesospheric cloud heights

Satellite data analyses indicate that variations of daily mean polar mesospheric cloud (PMC) height and mesopause height correlate on a range of intraseasonal time scales both short and long (i.e., ∼4 days to 2 months). The average of a multiyear analysis from OSIRIS/Odin, SNOE, AIM, and SABER/TIMED data sets in the polar regions north (south) of 65°N (°S) shows that on a daily basis the mean PMC height ( max) is located 3.5 km ± 0.5 km below the mean mesopause height ( mes) in both hemispheres throughout the season and for all years examined. The data show that the relationship persists over multiple PMC seasons. This is a robust result that has also been verified with thermodynamic equilibrium and microphysical modeling. Model results from a large number of ensemble simulations show that max remains ∼3.5 km below mes as long as the vertical average of the ambient temperature minus the frost point temperature difference over the supersaturated region is about ‐10 K or less for all the individual simulations. max is located less than 3.5 km below mes for warmer supersaturated region temperatures. The distance between the cloud and the mesopause heights (Zmes − Zmax or ΔZ) is controlled by the corresponding temperature structure in the supersaturated region. It is concluded that the variation of ΔZ is mostly driven by the variation of the temperature structure instead of the H2O mixing ratio magnitude or vertical distribution.