Morphology of gravity‐wave energy as observed from 4 years (1998–2001) of high vertical resolution U.S. radiosonde data

Abstract

Gravity‐wave energy densities have been derived from 4 years (1998–2001) of U.S. high vertical resolution (∼30 m) radiosonde wind and temperature data. This data set includes more than 90 stations that extend from 14°S to 71°N and 135°E to 55°W and cover such varied terrain as tropical islands, midcontinent plains, and mountainous regions, and they extend to the Arctic. This data set also includes both winds and temperatures in the troposphere and lower stratosphere for all stations. Thus analysis of this data set should be useful in distinguishing source effects from propagation effects. Some of the features found in this analysis are as follows. On the average, lower stratospheric gravity‐wave energies decrease poleward and are stronger in (Northern Hemisphere) winter than summer. Tropospheric gravity waves are also stronger in winter than summer, but they maximize at middle latitudes (35°–40°N). In the troposphere, gravity‐wave energy maxima exist over the Rocky Mountains, but in the lower stratosphere the energy maxima are mostly in the southeastern United States. Quasi‐Biennial Oscillation and El Nino–Southern Oscillation effects appear to account for much of the observed interannual variability in lower stratospheric gravity‐wave energy. The time series of tropospheric and lower stratospheric gravity‐wave energies are virtually uncorrelated with one another.