A Survey of Extratropical Cyclone Characteristics during GALE

Abstract

For the population Of cyclones that formed over North America and the adjacent Atlantic Ocean during the Genesis of Atlantic Lows Experiment (GALE; 13 January-16 March 1986), a variety of interrelationships between various cyclone characteristics are considered. Previous cyclone climatologies are extended by requiring no minimum cyclone amplitude. Particular attention is paid to the horizontal size distribution of the cyclones. It is found that 1) most cyclones are subsynoptic in scale, with only the deepest cyclones having a size consistent with classical baroclinic-instability theory; 2) almost all small-scale cyclones have a total life span of less than 48 h; 3) the pressure gradient within small-scale cyclones tends to be weaker than that within large-scale cyclones; 4) Atlantic cyclones deepen much more rapidly than cyclones over the continent but for many cyclones, deepening rate is an unsuitable measure of intensification; and 5) the geographical distribution of cyclogenesis during GALE is broadly similar to that found in more comprehensive climatologies, but some significant differences are present that are attributable to the inclusion of weak cyclones and stationary, orographically forced cyclones.