Satellite signatures of rapid cyclogenesis

Abstract

Animation of satellite visual and infrared imagery indicates that rapid cloud growth is a characteristic of explosively deepening cyclones. The working hypothesis in this thesis is that the intense vertical motions responsible for the low-level spin-up will produce rapid cloud expansion in the upper troposphere that can be detected using digital satellite data. Using digital IR data from GOES-West, the cloud growth of three explosive storms that developed over the eastern North Pacific Ocean were measured quantitatively and compared with the cyclone deepening rate. The results indicate that the growth in areal coverage of clouds colder than -45' C is most closely related to the explosive development period while the growth of the warmer cloud tops is related to the open wave stage. This relationship is dependent on the cloud pattern of the maturing cyclone. Correlations between cloud growth and pressure deepening were calculated but provide only a general estimate of the relationship between the two parameters. This study demonstrates the feasibility of using digitized satellite data to quantitatively analyze the cloud growth and structure of explosively developing cyclones.