Observational and Modeling Studies of the Mesoscale Land-Air-Sea Interaction Processes during GALE (1986)

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The rapid development and intensification of winter cyclones in coastal regions presents a major weather forecasting problem. Along the eastern seaboard, the development of cyclonic storms and frontal systems often occurs along the coastal region of the Carolinas. These weather systems may lead to severe weather in the heavily populated Northeast Corridor in the form of freezing rain, heavy snowfall, blizzards and extensive coastal erosion. In order to study these phenomena, the National Science Foundation sponsored an intensive field investigation known as the Genesis of Atlantic Lows Experiment (GALE). The field phase of the GALE was a two- month, multi-agency endeavor executed during the winter of 1986. As part of the GALE, the Principal Investigator was instrumental in designing and implementing a network to study the redistribution of heat and moisture in the lowest three kilometers of the atmopshere over the ocean which is known as the marine boundary layer (MBL). The MBL and ocean-atmosphere interaction processes appear to play an important role in the genesis of cyclones or in the intensification of an existing cyclone. Analysis to date has demonstrated the importance of the Gulf Stream and the land-air-sea interface in both the intensification of cyclonic storms and the formation of frontal systems. Low level forcing by boundary layer circulations and increase in baroclinic instability in the boundary layer appear to be primary mechanisms for storm intensification. Additionally, it has been found that differential boundary layer modification may be the main mechanism for the formation of some coastal fronts. Through diagnostic studies of the data collected during the GALE and numerical modeling the Principal Investigator will continue to explore the dynamics of coastal cyclogenesis and cyclonic storm intensification. Scientific questions to be addressed include: What is the relative contribution of surface forcing versus upper level forcing in offshore cyclogenesis? What is the relationship between the coastal frontogenesis and incipient cyclogenesis? What is the effect of coastal curvature on the offshore cyclogenesis? What is the role of the diurnal variation of the land processes on the coastal front?