Possible Contributions of Lid Conditions during Explosive Cyclogenesis
Abstract
Maritime soundings acquired during the Genesis of Atlantic Lows Experiment (GALE) Intensive Observing Periods (IOP's) 6 and 11 are evaluated to determine the presence of mid tropospheric, dry continental air that forms a capping inversion over cool, moist marine air, which is defined to be a lid. The strength of these lid conditions is evaluated using the Lid Strength Index (LSR) developed by Carlson et al. (1980) for continental thunderstorms. The environmental factors contributing to lid conditions and the lid's possible effects on explosive cyclogenesis are analyzed. During IOP 6, a predominantly zonal flow advects warm, dry continental air over the region upstream of the convective heat release. Consequently, the air sea fluxes and horizontal advection of moist air into the central region of the low are trapped below the lid. With the superposition of upper-level forcing that lifts and weakens the lid, the IOP 6 low develops explosively. During IOP 11, the mid-tropospheric air flow is more meridional and no-lid conditions occur upstream from the cyclone region. Consequently, the air-sea fluxes and horizontal advection of moisture is not confined to the lower troposphere. Although cyclogenesis occurs in this environment, it is not explosive. The presence of lid conditions during IOP 6 and the absence of lid conditions during IOP 11 are suggested to be one of the factors that differentiated explosive and non-explosive maritime cyclogenisis. Meteorology, Explosive cyclogenesis, Upper air sounding, Theses.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1988
- Accession Number
- ADA204961
Entities
People
- Charles W. Green
Organizations
- Naval Postgraduate School