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Proceedings with Extended Abstracts (single PDF file) - Radio ...

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of the refraction index are not equal to that of temperature, but may reflect small- andmesoscale dynamical changes in the atmosphere.Figure 6 reveals zonal mean variances of the refraction index average for entireduration of GPS/MET experiment in 1995 - 1997. At altitudes 15 – 25 km, one can seemaxima at latitudes between -20° and 20° in Figure 6. They may be connected <strong>with</strong> deepconvection in equatorial region. At altitudes 20 – 25 km, one can also see the maxima ofrefraction index variations at high latitudes of northern hemisphere. The variancesincrease at 35 km, and the maxima near the equator appear. At altitudes near 10 km,maxima of the variances are concentrated between latitudes 20° and 60° in both northernand southern hemispheres. These maxima correlate <strong>with</strong> locations of tropospheric jetstreams having maxima at altitudes 10 - 12 km. An analysis [see Gavrilov et al. 2003c]shows smaller variances in the winter troposphere and larger variances in the winterstratosphere. This may reflect seasonal variations of the intensity of wave sources in thelower atmosphere and of filtering of propagating IGWs by background winds andtemperatures in the middle atmosphere.Fig. 6. Zonal mean variances of the refraction index average for entire interval ofGPS/MET experiment in years 1995 - 1997.5. Numerical modeling of atmospheric general circulation.A simplified mathematical models and parameterization of wave thermal anddynamical effects for the inclusion of IGW effects to the numerical models ofatmospheric dynamics were developed. We used a version of COMMA-SPBU model ofgeneral circulation of the middle and upper atmosphere, initially developed in CologneUniversity and then modified in Leipzig University (Germany) [Frohlich et al, 2003] andin Saint-Petersburg State University (Russia). Compared to the other known analogousparameterizations of IGW effects, we took into account horizontal inhomogeneity ofgravity wave sources distributions in accordance <strong>with</strong> GPS satellite observations (seeabove).The subroutines for parameterization of accelerations of the mean flow and heatingrates due to breaking and dissipating IGWs come from simplifications of a numericalmodel of IGW generation and propagations, developed in Saint-Petersburg State173

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