Source Parameter Estimates from Radiosonde Data. by Marvin A. Geller - Stony Brook University Jie Gong - Stony Brook University Ling Wang - Colorado Research Associates

The “holy grail’ in gravity wave research is to develop a practical, physically justified gravity wave parameterization for use in general circulation models. McLandress and Scinocca (JAS, 1995, ) compared the performance of a number of gravity wave parameterization schemes and concluded that they gave very similar results if their wave breaking occurred as similar altitudes. This implies that determination of the source spectrum is the most important thing.

In a series of two papers (Vincent and Alexander, JGR, 105, 17,971-17,982 and Alexander and Vincent, JGR, 105, 17, ,993) derived time series of gravity wave energy and vertical flux of zonal momentum from high vertical-resolution radiosonde data for 6-years of data from Cocos Island (12 0 S, 97 0 E). They then did a best fit analysis to determine the gravity wave source spectrum that was most consistent with these results.

Solid Line - Gaussian, c = 0 Dotted Line = Gaussian, c = u 0 Dashed Line - Antisymmetric, Isotropic Dash-Dot Line - Antisymmetric, anisotropic (“moving mountain) Pfister et al., 1993, JGR From Alexander and Vincent (2000)

In his PhD thesis, Dr. Ling Wang did a similar analysis for 21 US radiosonde sites. He found that using the techniques of Alexander and Vincent (2000), he could get good fits to the time series for a four-year time series for lower stratosphere gravity wave energy and vertical flux of zonal momentum for 9 of these sites. Ms. Jie Gong, a Stony Brook PhD student, is extending this work to all of the 93 US radiosonde sites for an 8-year time series. Here, I show some early results.

High Correlation Examples St. Paul Island, AKKoror/Palau Island r = r = r = r = 0.553

Low Correlation Examples Wilmington, OH Yap Island r = r = r = r = 0.324

Some Conclusions 1. Among the 93 stations for which we have data, 4 lack sufficiently complete data to be analyzed. 2. Correlations have been calculated for 62 of these stations, and 31 have absolute values for the correlation,  r  > 0.25, between the lower stratospheric gravity wave energy and the vertical momentum flux of and  r  > 0.34 for the correlation between the source flux and the simulated momentum flux, which Dr. Ling Wang found to be necessary to get a “good fit” (E t ->  r  > 0.5, mom. flux ->  r  > 0.3, all with the same intermittency). 3. Simulations have been run so far for 32 stations, out of which a “good fit” is found for 19 of these, all of which satisfy Wang’s criteria.

Some Conclusions (continued) 4. Correlation for E t  r  > 0.5 can be obtained for all the simulated 32 stations with at least one combination of parameters. 5. The B1 spectral shape tends to give the “best fit” for  > 30 0 N, while the B4 spectral shape tends to give the “best fit for  < 30 0 N. 6. For the B1 type, x generally increases with latitude, while there’s no obvious trend for the B4 types. 7. All the “good fit” simulations are obtained with a source altitude of km.