Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Atmos. Chem. Phys., 13, 181-190, 2013
© Author(s) 2013. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
08 Jan 2013
Relationship between level of neutral buoyancy and dual-Doppler observed mass detrainment levels in deep convection
G. L. Mullendore1, A. J. Homann2, S. T. Jorgenson1, T. J. Lang3,*, and S. A. Tessendorf4 1Department of Atmospheric Sciences, University of North Dakota, Grand Forks, North Dakota, USA
2National Weather Service, Indianapolis, Indiana, USA
3Department of Atmospheric Science, Colorado State University, Fort Collins, Colorado, USA
4Research Applications Laboratory, NCAR, Boulder, Colorado, USA
*now at: NASA Marshall Space Flight Center, Huntsville, Alabama, USA
Abstract. Although it is generally accepted that the level of neutral buoyancy (LNB) is only a coarse estimate of updraft depth, the LNB is still used to understand and predict storm structure in both observations and modeling. This study uses case studies to quantify the variability associated with using environmental soundings to predict detrainment levels. Nine dual-Doppler convective cases were used to determine the observed level of maximum detrainment (LMD) to compare with the LNB. The LNB for each case was calculated with a variety of methods and with a variety of sources (including both observed and simulated soundings). The most representative LNB was chosen as the proximity sounding from NARR using the most unstable parcel and including ice processes.

The observed cases were a mix of storm morphologies, including both supercell and multicell storms. As expected, the LMD was generally below the LNB, the mean offset for all cases being 2.2 km. However, there was a marked difference between the supercell and non-supercell cases. The two supercell cases had LMDs of 0.3 km and 0.0 km below the LNB. The remaining cases had LMDs that ranged from 4.0 km below to 1.6 km below the LNB, with a mean offset of 2.8 km below. Observations also showed that evolution of the LMD over the lifetime of the storm can be significant (e.g., >2 km altitude change in 30 min), and this time evolution is lacking from models with coarse time steps, missing significant changes in detrainment levels that may strongly impact the amount of boundary layer mass transported to the upper troposphere and lower stratosphere.

Citation: Mullendore, G. L., Homann, A. J., Jorgenson, S. T., Lang, T. J., and Tessendorf, S. A.: Relationship between level of neutral buoyancy and dual-Doppler observed mass detrainment levels in deep convection, Atmos. Chem. Phys., 13, 181-190,, 2013.
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