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

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

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University [Gavrilov and Fukao, 1999]. In this study, we developed a modification ofLindzen-type parameterization using 200 IGW harmonics covering the ranges of IGWhorizontal phase speeds of 3 - 150 m/s, and eight azimuths of IGW propagation.An analysis of GPS/MET satellite data (see section 4) shows inhomogeneity oflatitude-longitude distributions of IGW intensity, which may be different at differentaltitudes. To incorporate these realistic distributions of IGW intensities into atmosphericgeneral circulation models, we modified the wave parameterizations to be able to specifyboundary conditions for IGW spectrum at any height in the atmosphere. Theparameterization was included into the COMMA-SPBU general circulation model.To study the sensitivity of the general circulation of the middle atmosphere to thelatitudinal distribution of lower atmosphere wave sources, we made calculations <strong>with</strong> theCOMMA-SPBU model for constant values of wave velocity variances at altitude 30 kmand their latitude distributions shown in Figure 7. These distributions reflect the mainstructures of tropo-stratospheric jet streams and convective patterns observed <strong>with</strong>GPS/MET satellite at Figure 6.Fig. 7. Model latitude distributions of IGW variances for July at altitude 30 km reflectingconstant value (dash-dotted line), seasonal variations (long dashes), winter pole maximum(thin solid line), equatorial maximum (thick solid line) and mid-latitude maxima (shortdashes).Figures 8 and 9 present examples of height-latitude distributions of wind andtemperature calculated <strong>with</strong> COMMA-SPBU numerical general circulation model forJuly and, respectively, for homogeneous and inhomogeneous (according to the totallatitude distribution of the IGW intensity from Figure 7). One can see that taking accountof realistic horizontal distribution of IGW activity gives better reversal of generalcirculation above the mesopause. An analysis by Gavrilov et al. (2003d) shows thatstructure of general circulation of the middle atmosphere is most sensitive to the wavevariances in the middle latitudes.174

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