Emergent Properties of Deep Convective Ensembles in OTREC

David J. Raymond and Zeljka Fuchs
New Mexico Tech
  17 Mar, Noon, in 2155

We postulate that the statistical characteristics of ensembles of convection over tropical oceans are actually simpler than the characteristics of individual convective cells. This postulate is based on the hypothesis that the mean characteristics of convective ensembles depend only on the static properties of the environment, i.e., horizontal wind and thermodynamic profiles plus sea surface temperature. Dynamic processes such as externally imposed convergence are assumed to have long time scales so that their action is manifested by their cumulative effects on atmospheric profiles. Several field programs studying tropical oceanic convection suggest that a small number of parameters derived from thermodynamic profiles can explain a significant part of the variance in such convection. Preliminary results from the OTREC (Organization of Tropical East Pacific Convection) project support and extend these conclusions. As with any metrics of atmospheric convection, the chaotic nature of the process introduces significant noise. Nevertheless, our results provide constraints which may be useful in the construction of parameterizations of deep convection over tropical oceans.