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Ann. Geophys., 26, 1233-1241, 2008
www.ann-geophys.net/26/1233/2008/
© European Geosciences Union 2008
Climatic variability of the mean flow and stationary planetary waves in the NCEP/NCAR reanalysis data
A. Yu. Kanukhina, E. V. Suvorova, L. A. Nechaeva, E. K. Skrygina, and A. I. Pogoreltsev
Russian State Hydrometeorological University, Maloohtinsky 98, St. Petersburg, 195196, Russia
Abstract. NCEP/NCAR (National Center for Environmental Prediction – National Center for Atmospheric Research) data have
been used to estimate the long-term variability of the mean flow,
temperature, and Stationary Planetary Waves (SPW) in the troposphere and lower stratosphere.
The results obtained show noticeable climatic variabilities in
the intensity and position of the tropospheric jets that are
caused by temperature changes in the lower atmosphere. As a result,
we can expect that this variability of the mean flow will cause
the changes in the SPW propagation conditions. The simulation of
the SPW with zonal wave number m=1 (SPW1), performed with a
linearized model using the mean flow distributions typical for the
1960s and for the beginning of 21st century, supports this
assumption and shows that during the last 40 years the amplitude
of the SPW1 in the stratosphere and mesosphere
increased substantially. The analysis of the SPW amplitudes
extracted from the geopotential height and zonal wind NCEP/NCAR
data supports the results of simulation and shows that during the
last years there exists an increase in the SPW1 activity in the
lower stratosphere. These changes in the amplitudes are
accompanied by increased interannual variability of the SPW1, as well.
Analysis of the SPW2 activity shows that changes in its amplitude
have a different sign in the northern winter hemisphere and at
low latitudes in the southern summer hemisphere. The value of the
SPW2 variability differs latitudinally and can be explained by
nonlinear
interference of the primary wave propagation from below and from secondary SPW2.
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