Isolating the Impact of Local and Large-Scale Forcings on Surface Triggered Convection

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Monday, 3 February 2014: 11:00 AM
Room C210 (The Georgia World Congress Center )
Ahmed Tawfik, COLA, Fairfax, VA; and P. Dirmeyer

To properly evaluate the role of the land surface (e.g. soil moisture) in convective development, the large-scale atmospheric forcing must be separated from the local surface flux forcings in a manner physically consistent with surface-boundary layer interactions. A diagnostic framework (the mixed condensation level, MCL, framework) for dissecting these individual forcings is presented. The MCL framework includes two sets of variables: 1) one set describes the degree to which the atmosphere is preconditioned to moist convection and is translatable into surface flux units, and 2) another set quantifies the surface flux conditions necessary for convective initiation. This methodology can be applied to any time of day or year using standard temperature and humidity profiles. The MCL is shown to be applicable over a wide range of climate regimes, and responds to synoptic and mesoscale forcings illustrating its broader utility.