International Journal of Geomagnetism and Aeronomy
Vol. 4, No. 1, April 2003
Long-term changes in the stratopause height and temperature derived
from rocket measurements
at various latitudes
E. V. Lysenko and V. Ya. Rusina
Abstract
Statistical analysis
is performed
of the weekly measurements of the temperature at
altitudes of 25-75 km by meteorological rockets M-100B during
1969-1995 at the Heiss Island (81o N), Volgograd (49o N), Thumba
(8o N), and Molodezhnaya (68o S) sites.
A linear
approximation of the temporal series of the data for every month of a
year with "filtered out" long-term component made it possible to draw
vertical temperature profiles and to evaluate the changes of the
stratopause temperature and height for the entire observational
period. A statistically significant at the
P = 0.95 level depletion of
the stratopause height by 0.4, 0.5, and 2.4 km above Heiss Island,
Thumba, and Volgograd, respectively, is detected. The stratopause
height above Molodezhnaya did not change. The stratopause descent at
Volgograd and Thumba occurred during all seasons except for the spring
months. The maximum decrease of the stratopause height by 5-7 km was
observed above Volgograd in winter months. The stratopause descent
above Heiss Island occurred only in January (by 2.4 km), February
(by 4.5 km), and March (by 1.0 km). The stratopause temperature decreased
statistically significantly above Heiss Island (by 4.9 K),
Volgograd (by 2.8 K), and Thumba
(by 4.0 K) and increased by 1.0 K (statistically insignificant at
P =0.95 ) above Molodezhnaya. The stratopause temperature changes obtained
agree with the mean trend values in the 45-50 km layer published
earlier. Estimates of the monthly mean changes of the stratopause
temperature are presented. An assumption that the ozone decrease
during the recent decades is the main reason of the stratopause
depletion observed is discussed.