Can detailed satellite analysis distinguish between developing and strong non-developing tropical disturbances?

Many developing and non-developing vorticity maxima have been manually tracked using ERA-40

Reanalysis. The tracks have been done for June-October 1998-2001 in the eastern North Pacific and

North Atlantic. For the developing systems, the vorticity maxima are tracked back over 48 hours prior to

genesis. For the non-developing systems, the systems were first identified on Hovmoller plots of

vorticity then manually tracked (for 1998-2001). The difficulty and time factor involved in tracking the

non-developing disturbances has been a major obstacle to their detailed analysis. The strong non-developing

systems are defined as those with vorticity, shear, and SST similar to the developing systems

and with significant convective activity for at least 48 consecutive hours. The cases presented here have

particularly good sampling by TRMM and/or SSMI.

The underlying question is the relative importance of convection and the large-scale in controlling

cyclogenesis. If the differences in the large-scale are accounted for, there may still be differences in the

nature of convection; for example, there may be more and/or more persistent hot towers in the developing

systems. Comparisons are made with respect to “bulk” measures of convective activity: cold cloud,

rainfall, and heavy rainfall coverage. Further, individual convective systems (i.e. MCSs) observed by

TRMM and/or SSMI are isolated and compared with the background convective climatology. Finally,

high quality VIS and IR satellite data are used in an attempt to characterize the interactions of the

convective systems.