US Climate Variability and Predictability Program

Mesoscale Convective Systems (MCSs) in the Intra-Americas Seas (IAS): Evidence from TRMM (for Session 1)

Department of Atmospheric Sciences, University of Utah, USA
Session I: Identifying opportunities and challenges of observing and modeling IAS variability and its teleconnections
16 years of data from TRMM is used to characterize the occurrence and distribution of MCSs and their contribution to rainfall over the IAS region. The primary tool is the precipitation feature (PF) database (Liu et al., JAMC 2008). In addition, this database permits analysis of the vertical structure of precipitation systems with a level of detail previously possible only in intensive observational field campaigns, which by their nature are limited in location and duration. The IAS region is notable for the extreme variety of its rainfall climatology, and the size and intensity of its convective systems. For example. the Caribbean is unique in the region for having only a small fraction of its rain coming from MCSs or from deep or intense convection, while the opposite is true for the east Pacific on the opposite side of Central America. The land regions also differ enormously; deep and intense convection is the dominant mode of precipitation in only one region: northwestern Columbia. Another unique region is coastal western Columbia, with the word record rainfall, but rainfall that seems to be underestimated by the TRMM retrieval algorithms. In general, oceanic rainfall comes from larger systems (except over the Caribbean) than land rainfall. Central Mexico’s rainfall comes mostly from small PFs, while rain on the Pacific Coast from central Mexico to Columbia comes mostly from large PFs.
Presentation file