Correlation 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 intra-seasonal time scales both short and long. The average of a multiyear analysis from OSIRIS/Odin, SNOE, AIM and SABER/TIMED data sets in the polar regions north/south of 65 degree N/S show that the two heights remain separated by a constant offset of about 3.5 km ± 0.5 km in both hemispheres. Results show that the relationship persists over multiple PMC seasons. The 3.5km separation holds up as long as the mean temperature averaged over the supersaturated region in the vicinity of the mesopause is colder than or approximately equal to a value of about 10K below the frost point temperature. This constant offset is a robust relationship that has been verified by both data and modeling. The PMC peak height is located less than 3.5km below the mesopause for warmer supersaturated region temperatures. The distance between the cloud and mesopause heights is controlled by the temperature vertical distribution in the supersaturated region. The H2O mixing ratio magnitude and vertical distribution is a factor in the relationship but it appears to be of minor importance.