Observations from the Bow Echo and MCV Experiment (BAMEX)
Christopher Davis, NCAR, Boulder, CO; and N. Atkins, G. Bryan, W. Cotton, D. Dowell, J. M. Fritsch, B. Jewett, R. Johns, D. Jorgensen, K. Knupp, W. C. Lee, G. McFarquhar, R. Przybylinski, B. Rauber, B. Smull, J. Trapp, S. Trier, R. Wakimoto, M. Weisman, and C. Ziegler
Preliminary results from the Bow Echo and MCV Experiment (BAMEX) are summarized. BAMEX is a study using highly mobile platforms to examine the life cycles of mesoscale convective systems. It represents a combination of two related programs to investigate (a) bow echoes, principally those which produce damaging surface winds and last at least 4 hours and (b) larger convective systems which produce long lived mesoscale convective vortices (MCVs). MCVs can focus new convection and play a key role in multi-day convective events affecting a swath sometimes more than 1000 km in length with heavy to perhaps flooding rains. The main objectives regarding bow echoes are to understand and improve prediction of the mesoscale and cell-scale processes that produce severe winds. For MCV producing systems the objectives are to understand MCV formation within MCSs, the role of MCVs in initiating and modulating convection, the feedback of convection onto MCV intensity, and to improve the overall predictability of the vortex-convection coupled system.
BAMEX utilizes three aircraft, two equipped with dual Doppler radar capability, the third equipped with dropsondes, to map the mesoscale evolution of long-lived MCSs including the development of mesoscale vortices and rear-inflow jets. Dropsondes will be used to document environmental structure, thermodynamic structure of the stratiform region (where rear-inflow jets and MCVs reside) and to capture the structure of mature MCVs in the absence of convection. In addition, a mobile array of ground-based instruments will be used to document the thermodynamic structure of the PBL, including any existing convergence boundaries, probe the surface cold pool, and measure surface horizontal pressure and wind variations behind the leading convective line. The combination of aircraft and ground-based measurements is important for understanding the coupling between boundary-layer and free-tropospheric circulations within MCSs, and, in particular, how the rear-inflow penetrates to the surface in nocturnal severe wind cases.
Extended Abstract (396K)
Session 1B, MCS/Orographic Precipitation
Wednesday, 6 August 2003, 10:45 AM-12:30 PM
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