Convective Meteorology (Mesoscale Dynamics)

Identifying and characterizing atmospheric bores during IHOP_2002

Kevin Haghi
OU School of Meteorology

25 April 2014, 3:00 PM

National Weather Center, Room 5600
120 David L. Boren Blvd.
University of Oklahoma
Norman, OK

How familiar are we with the behavior of atmospheric bores? An investigation of the International H20 Project (IHOP_2002) provides conflicting findings to previous work, along with new ideas about how to treat the nature of bores. A systematic study categorize fine-line boundaries identified in the nocturnal and near nocturnal environment (22-12 UTC), lead by radar images coupled with the available Multiple Antenna PRofiler (MAPR), surface observations and soundings. Over one month of data provides 143 fine-line boundaries, 65 of which are consistent with atmospheric bores; this is in conflict to the Wilson and Roberts (2006) study of radar fine-lines. Meanwhile, pure density currents that are not associated with generating bore-like features are relatively rare (8 cases out of 143). Moreover, atmospheric bores were visible most frequently over the Texas-Oklahoma panhandle and the southern stretch of Kansas. Radar images seem to suggest that these are in phase with the surface frontal boundaries, but out of phase with the maximum in rainfall accumulation during the same period.

Atmospheric bores, although identified in multiple previous case studies, assumed two dimensionality about the atmospheric bore fronts. Bootstraps of the mean of fine-line boundary rotations reveal a 2σ deviation from 0, suggesting atmospheric bores and density currents frequently exhibit clockwise rotations and three dimensionality of bores seems more appropriate. Additionally, according to radar, with only 25% of density current duration explainable by the bootstrapped atmospheric bores indicate that atmospheric bores are surviving longer and later into the night. Discussion ensues to the nature of applying convective and hydraulic theory to atmospheric bores.

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