In the present talk, two topics related to jet/front GWs will be presented: (i) stratospheric gravity waves (GWs) in the southern-hemisphere high latitudes and their correlation with jet/front system, and (ii) characteristics of gravity waves in a baroclinic instability simulation. In (i), ECMWF high-resolution analysis in January and July 2007 and GW momentum flux (GWMF) estimated from HIRDLS satellite observations in Feb. 2005-Feb. 2008 are used. To examine the association of GWs with jet/front system, the frontogenesis function (FF) at 600 hPa and the residual of the nonlinear balance equation (∆NBE) are calculated using ERA-Interim. The zonal GWMF in the lower stratosphere (70 hPa) from ECMWF analysis is negative in wintertime, concentrated in major mountain regions, with a widely distributed secondary maximum along Southern ocean near 60oS, and it sustains in the upper stratosphere (5 hPa). In summertime, weak positive GWMF is distributed in wide region at 70 hPa with relatively large values near the Antarctic coastline, but strong negative GWMF appears near southern tip of Andes. The absolute GWMF from the ECMWF analysis at 5 hPa is well correlated with that from HIRDLS, as well as FF and ∆NBE. In (ii), an idealized baroclinic instability case is simulated using a 10 km resolution global model to investigate the characteristics of GWs during the evolution of the baroclinic wave. Three groups of GWs appear around high-latitude surface trough at the mature stage of the baroclinic wave, with horizontal and vertical wavelengths of 40-400 km and 3-10 km, respectively, and they are trapped mostly below the tropospheric westerly jet. On the other hand, at a breaking stage of the baroclinic wave, two groups of quasi-stationary GWs with horizontal and vertical wavelengths of 60-400 km and 5-14 km, respectively, appear near the surface low, and they can propagate vertically into the stratosphere.

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*email: chunhy@yonsei.ac.kr
*Preference: Invited