pertaining to the larger, deeper systems. Figure 3 shows the cyclogenesis and 

 Figure 4 shows the cyclolysis density of travelling cyclones during GALE. 

 Note the maximum in the vicinity of the Chesapeake Bay area with a second- 

 ary maximum in the western Atlantic. Figure 5 shows the distribution of 

 maximum cyclone sized during GALE. 



Figures. Number of cyclogenesis events per 3x10^ km^ during GALE, 

 traveling cyclones only (from Neilsen and Dole (1992)) 



A 12-mb pressure deficit (relative to the nearest adjacent col) was arbi- 

 trarily selected as representing prominent cyclones; at a 4-mb contour interval 

 this deficit would be depicted by three closed isobars. The average radius of 

 systems attaining a 12-mb deficit was approximately 1,500 km. During the 

 GALE, only about 20 percent of all the systems that formed attained the char- 

 acteristics of prominent cyclones. Separating all formed cyclones into promi- 

 nent and non-prominent classes showed that the smaU-scale, non-prominent 

 cyclones had a mean duration of 18 hr, the prominent cyclones had a mean 

 duration of 83 hr. Figure 6 shows the relationship between the maximum 

 radius attained and the cyclone duration (length of time the system appeared 

 on weather charts). Note that there are a comparatively greater number of 

 long-lived small cyclones than there are short-lived large cyclones. 



Cyclone intensification is commonly estimated by the temporal change in 

 central pressure (deepening). This measure of intensification is reliable when 

 the far-field pressure remains constant; then the deepening will equal the 

 spatial pressure deficit However, when more than one system is in the 



Chapter 2 Operational Analysis Depictions 



