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Conclusions:

From preliminary analysis of the high resolution U.S. radiosonde data for the year 1998 we find the following:

• In the lower stratosphere, gravity wave energies decrease poleward at all latitudes from the tropics to the Arctic regions and are stronger in winter than in summer.

• Gravity wave energies in the lower stratosphere are greater in the vicinity of the Rocky Mountains in all seasons, especially in fall and winter, with a smaller enhancement over the Appalachian Mountains.

• In the troposphere, approximately 50% of the gravity wave energy shows upward energy propagation while there is about 75% upward propagation in the lower stratosphere.

• The seasonal variation of stratospheric gravity energies correlates very well with tropospheric jet wind speeds.

• In the lower stratosphere, on the average, gravity wave intrinsic frequencies (scaled by the Coriolis parameter f), vertical wavelengths, and horizontal wavelengths all decrease poleward, and gravity waves propagate eastward south of about 30°N, and westward north of 30°N.