NWC REU 2004
May 24 - July 31



Annual Cycles of Thermodynamic Parameters from Global Reanalysis Data

Heather Flachs and Harold Brooks



Annual cycles of sounding-derived parameters have been limited in their use, because of the lack of data from around the world. The purpose of this study was to identify annual cycles and the variability of four thermodynamic parameters: Convective Available Potential Energy (CAPE), the magnitude of vector wind difference between surface and 6-km above ground level (hereafter Deep Shear), the mean mixing ratio in the lowest 100-hPa (hereafter mixing ratio), and 700-hPa—500-hPa lapse rate. The artificial soundings were created by using a global reanalysis dataset. Years analyzed were 1975, 1987, and 1995-1999. Locations chosen included locations in the United States, east of the Rocky Mountains, and in Europe. Relationships between CAPE and Deep Shear were identified as well as relationships between lapse rates and mixing ratios. Mean threshold mixing ratios were identified for the use of determining the cycle of moisture throughout the year for the United States and Europe. These were compared to the storm activity in the locations analyzed. A part of Europe was identified as having similar cycles as the upper Great Plains of the United States. By knowing the annual cycles and storm activity in the United States, we were able to apply the same concepts to Europe in areas that lacked good storm activity reporting.

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