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AOSC Departmental Seminar
February 19, 2015

Use of Observations to Evaluate Model Simulations of Convective Transport

Gretchen Mullendore
Department of Atmospheric Sciences, University of North Dakota

Updrafts in severe storms are the most efficient pathways for vertical mass transport in the atmosphere.  Regional simulations show the importance of storm morphology in estimating convective transport, morphology that is often not captured in the coarse-scale models.  However, the majority of verification done on regional weather models involves precipitation and low-level reflectivity.  There are relatively few observations that can be used to constrain the storm-scale behavior in the upper-troposphere and lower-stratosphere (UTLS).  Using radar reflectivity as an approximation of the observed storm-scale convective mass detrainment profile has produced promising results.  An update of the most recently published reflectivity-only method for constraining transport will be discussed.

Another source of uncertainty in the UTLS is caused by the highly perturbed state of the tropopause, making quantifying irreversible convective transport into the stratosphere difficult.  In situ measurements from aircraft provide valuable measurements of UTLS chemical plumes downwind of deep convection.  Enhanced carbon monoxide plumes are identified from aircraft vertical profiles, and back trajectories and observations of precipitation are used to verify which plumes had a recent convective source.  The tropopause structure in the vicinity of each plume is then analyzed.  Preliminary results show the majority of plumes show double tropopause structures, which have been recently shown to be favorable for irreversible transport.  However, the strength of the primary tropopause inversion appears to strongly impact the magnitude of such transport.