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要旨

Observations of tropospheric gravity waves (GWs) made by the new and extensive USArray Transportable Array (TA) barometric network located east of the Rockies, in the central and eastern United States and of stratospheric (30-40 km above sea level) GWs made by the Atmospheric Infrared Sounder (AIRS) are compared over a 5 year time span from 2010 through 2014. GW detections in the period band from 2 to 6 h made at the Earth's surface during the thunderstorm season from May through August each year exhibit the same broad spatial and temporal patterns as observed at stratospheric altitudes. At both levels, the occurrence frequency of GWs is higher at night than during the day and is highest to the west of the Great Lakes. Statistically significant correlations between the variance of the pressure at the TA, which is a proxy for GWs at ground level, with 8.1 mu m brightness temperature measurements from AIRS and rain radar precipitation data, which are both proxies for convective activity, indicate that GWs observed at the TA are related to convective sources. There is little, if any, time lag between the two. Correlations between GWs in the stratosphere and at ground level are weaker, possibly due to the AIRS observational filter effect, but are still statistically significant at nighttime. We conclude that convective activity to the west of the Great Lakes is the dominant source of GWs both at ground level and within the stratosphere.
Plain Language Summary Observations of tropospheric gravity waves made by the USArray Transportable Array (TA) barometric network located in the central and eastern United States and of stratospheric gravity waves made by the Atmospheric Infrared Sounder were compared over a 5 year time span from 2010 through 2014. Analysis of the TA data shows a gravity wave hot spot that is located on the Earth's surface west of the Great Lakes. Gravity wave occurrence rates on the ground exhibit the same broad spatial and temporal patterns as observed at stratospheric altitudes. Evidence suggests that convective activity is the dominant source of gravity waves both at the ground and in the stratosphere.