Mechanisms initiating deep convection over complex terrain during COPS

AMS Citation:
Kottmeier, C., and Coauthors, 2008: Mechanisms initiating deep convection over complex terrain during COPS. Meteorologische Zeitschrift, 17, 931-948, doi:10.1127/0941-2948/2008/0348.
Date:2008-12-01
Resource Type:article
Title:Mechanisms initiating deep convection over complex terrain during COPS
Abstract: Precipitating convection in a mountain region of moderate topography is investigated, with particular emphasis on its initiation in response to boundary-layer and mid- and upper-tropospheric forcing mechanisms. The data used in the study are from COPS (Convective and Orographically-induced Precipitation Study) that took place in southwestern Germany and eastern France in the summer of 2007. It is found that the initiation of precipitating convection can be roughly classified as being due to either: (i) surface heating and low-level flow convergence; (ii) surface heating and moisture supply overcoming convective inhibition during latent and/or potential instability; or (iii) mid-tropospheric dynamical processes due to mesoscale convergence lines and forced mean vertical motion. These phenomena have to be adequately represented in models in order to improve quantitative precipitation forecast. Selected COPS cases are analysed and classified into these initiation categories. Although only a subset of COPS data (mainly radiosondes, surface weather stations, radar and satellite data) are used here, it is shown that convective systems are captured in considerable detail by sensor synergy. Convergence lines were observed by Doppler radar in the location where deep convection is triggered several hours later. The results suggest that in many situations, observations of the location and timing of convergence lines will facilitate the nowcasting of convection. Further on, forecasting of the initiation of convection is significantly complicated if advection of potentially convective air masses over changing terrain features plays a major role. The passage of a frontal structure over the Vosges - Rhine valley - Black Forest orography was accompanied by an intermediate suppression of convection over the wide Rhine valley. Further downstream, an intensification of convection was observed over the Black Forest due to differential surface heating, a convergence line, and the flow generated by a gust front.
Peer Review:Refereed
Copyright Information:Copyright 2008 Gebrüder Borntraeger, Berlin - Stuttgart.
OpenSky citable URL: ark:/85065/d7bp03f6
Publisher's Version: 10.1127/0941-2948/2008/0348
Author(s):
  • Christoph Kottmeier
  • Norbert Kalthoff
  • Christian Barthlott
  • Ulrich Corsmeier
  • Joel Van Baelen
  • Andreas Behrendt - NCAR/UCAR
  • Rainier Behrendt
  • Alan Blyth - NCAR/UCAR
  • Richard Coulter
  • Susanne Crewell
  • Paolo Di Girolamo
  • Manfred Dorninger
  • Cyrille Flamant
  • Thomas Foken
  • Martin Hagen
  • Christian Hauck
  • Hartmut Holler
  • Heike Konow
  • Michael Kunz
  • Holger Mahlke
  • Stephen Mobbs
  • Evelyne Richard
  • Reinhold Steinacker
  • Tammy Weckwerth - NCAR/UCAR
  • Andreas Wieser
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