Terminal versus transient cumulus congestus: A CloudSat perspective

Abstract

While cumulus congestus as an important mode of tropical convection has been established, many of the previous studies that rely on radar observations usually capture them as snapshots. A logical question to consider is: are the statistics gathered from snapshot observations of cumulus congestus really reflective of this mode of convection that ceases its growth at these intermediate levels (terminal cumulus congestus), or will the convection being observed continue to ascend to greater altitudes to become deep convection at a later time (transient cumulus congestus)? This short article strives to answer this question by analyzing simultaneous, independent measurements of CTH and CTT from CloudSat and MODIS, together with CloudSat radar profile and collocated ECMWF analysis. It is found, based on analysis of one year of data, that a significant fraction (∼30-40%) of the tropical cumulus congestus observed by the snapshot views are in transient mode that will ascend to greater altitude at a later time. The analysis concept used in this study, which gives "static" snapshot observations some "dynamic" context, can be applied to analyze convection of all types. Copyright 2009 by the American Geophysical Union.