A Proposed Method of Surface Map Analysis

Abstract

Present surface frontal analyses suffer from the defect that frontal positions are typically not collocated with zones of intense temperature contrast. Further, individuals typically do not agree as to the existence, type, and location of fronts. The author argues that the lack of a surface temperature analysis is mainly responsible for these flaws, and it is proposed that such analysis, preferably of potential temperature in regions of variable terrain elevation, become part of routine procedure. Such an analysis will reveal nonfrontal baroclinic zones of considerable intensity. Most cold fronts, except the strongest ones, are denoted as baroclinic troughs, propagating eastward in the prevailing westerly flow. It is argued that when a meridional cold front exists in the presence of even a small meridional temperature gradient, the wind shift should propagate away from the intense surface temperature gradient, which then weakens. An explanation is provided, based on quasigeostrophic theory. It follows that fronts are short-lived phenomena.