Session 9.5 Observations of tropospheric, convectively generated gravity waves from atmospheric profiling platforms

Tuesday, 18 August 2009: 2:45 PM
The Canyons (Sheraton Salt Lake City Hotel)
Daniel R. Adriaansen, University of North Dakota, Grand Forks, ND; and M. J. Alexander and G. L. Mullendore

Presentation PDF (1.1 MB)

Modeling studies have shown that convectively generated gravity waves in the forward environment can aid in triggering new convection. Several sources of atmospheric profiling data are analyzed to provide possible observations of the mechanisms revealed by the models. Data collected with the University of Alabama Huntsville's Mobile Integrated Profiling System (MIPS) during the Bow echo and Mesoscale convective vortex EXperiment (BAMEX) were analyzed for two different cases. Microwave Profiling Radiometer (MPR) measurements of temperature, water vapor, and relative humidity were obtained for both cases well in advance of organized convection. In both cases, signals from all three fields suggestive of so-called ‘mode 2' low frequency waves were observed. Temperatures in the 5-7 km layer warmed as the convection approached, and cooled slightly in the 3-5 km layer. Water vapor observations also indicate trends consistent with the presence of the mode 2 signal. However, an increase in water vapor in both cases occurred in a layer much deeper than what the mode 2 signal would produce. Infrared cloud base temperature observations confirmed the presence of a lowering cloud base in both cases, which is indicative of a leading stratiform type system. In addition to low frequency wave analysis, diagnosis of stability in the forward environment can help identify conditions when high frequency gravity waves may become trapped within the troposphere. Data from the Tropical Warm Pool International Cloud Experiment (TWP-ICE) are used to indentify high frequency signals from organized convection. Preliminary results from wavelet analysis of wind profiler data and implications for convective initiation will be discussed.
- Indicates paper has been withdrawn from meeting
- Indicates an Award Winner