The first quantitative estimation of the influence of volcanic activity
on noctilucent clouds
Abstract
Climate change happening in the middle and upper atmosphere has been
intensively investigating nowadays. One of the experimental tools to
investigate long-term changes in the mesopause region between 80 and 90
km altitude is a natural atmospheric phenomenon called noctilucent
clouds (NLCs). Being composed of tiny ice particles, NLCs are supposed
to be highly sensitive to small changes in the temperature and amount of
water vapor at the polar summer mesopause. Many factors such as solar
activity, long-term changes in the temperature, amount of water vapor,
minor atmospheric constituents, have been considered contributing to
long-term NLC changes. At the same time, a role of volcanic activity in
the NLC variability has been investigated in a qualitative sense in
previous studies so far, and its influence has been found to be
inconclusive. For the first time, we quantitatively investigate a factor
of volcanic activity in NLC variability for the past five decades. Our
analysis reveals that there is statistically significant positive
influence of volcanic activity on changes in NLC activity, with a time
lag of 7 years between these processes which might be explained by a
slow meridional-vertical updraft of ejected volcanic water vapor from
the tropical troposphere to the polar mesopause region. We confirm our
previous results on no statistically significant long-term trend in NLC
activity at middle and subpolar latitudes for the past five decades.