The potassium density and temperature structure in the mesopause region (80–105 km) at a low latitude (28°N)

By means of a groundbased lidar we have measured potassium layer parameters and the temperature structure in the mesopause region during 55 nights in 1999 at Tenerife (28°N). The potassium density shows a seasonal variation similar to that at midlatitudes. We also study the nocturnal mean temperatures and their seasonal variations and derive new evidence for the global two‐level structure of the mesopause. About midsummer we observed the mesopause close to 86 km with about 183 K for a period of four weeks. Transition periods between the regular (high) and the low altitude state of the mesopause were two weeks each.