Recorded presentation2.2
A Review of Observations of Cold Fronts, Including Prefrontal Troughs and Wind Shifts
David M. Schultz, NOAA/NSSL and CIMMS/Univ. of Oklahoma, Norman, OK
Fred Sanders has made considerable contributions to understanding and
analyzing the structure and dynamics of surface cold fronts. His
frontal research is reviewed in the context of the classical structure
and dynamics of cold fronts, as epitomized by his 1955 paper ``An
Investigation of the Structure and Dynamics of an Intense Surface
Frontal Zone.'' Characteristics of classical cold fronts are
summarized and explained. Sanders' research is then reviewed in the
context of nonclassical structure, where the surface pressure trough
and/or wind shift precedes the temperature gradient (hereafter called
prefrontal troughs or prefrontal wind shifts,
respectively). The states of these two extremes are termed
simultaneity and nonsimultaneity, respectively. A number of proposed
mechanisms for the formation of prefrontal troughs and prefrontal wind
shifts are reviewed. These mechanisms include those external to the
front: synoptic-scale evolution, interacting lower- and
mid-tropospheric fronts, fronts moving over topography, lee troughs or
drylines, and translating axis of dilatation. These mechanisms also
include those internal to the front: along-front temperature
gradients, a mechanism proposed by Orlanski and Ross, moist processes,
prefrontal descent of air, ascent of air at the front, mixing at the
front, and gravity waves and bores. Further information can be found
at http://www.cimms.ou.edu/~schultz/sanders/paper. Recorded presentation
Session 2, Mesoscale Weather Systems (Room 617)
Monday, 12 January 2004, 10:45 AM-12:00 PM, Room 617
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