HR: 17:35h
AN: A44B-06    [Abstracts]
TI: Stratiform and convective precipitation in 2-D cloud resolving simulations.
AU: * Rondanelli, R F
EM: rrondane@mit.edu
AF: Program in Atmospheres, Oceans and Climate, EAPS, MIT, 77 Massachusetts Avenue, Cambridge, MA 02139, United States
AU: Damour, C
EM: chris.dam@gmx.net
AF: Ecole Polytechnique, Palaiseau, France
AU: Lindzen, R S
EM: rlindzen@mit.edu
AF: Program in Atmospheres, Oceans and Climate, EAPS, MIT, 77 Massachusetts Avenue, Cambridge, MA 02139, United States
AB: There is observational evidence that the partition of precipitation into stratiform and convective is correlated with the local sea surface temperature. At least two competing mechanisms can be proposed to explain these observations based on an increase in the efficiency of precipitation with higher SST. The first is that the increase in efficiency is a consequence of the increase in specific humidity in the air that participates in convection which consequently increases the efficiency of collection-coalescence processes inside the convective clouds. A second possibility is simply that precipitation is more efficient in regions of higher mid-tropospheric humidity (which coincide geographically with regions of higher precipitation and higher SST) due to less dilution of dry air into the cloud. We will investigate how these mechanisms operate in idealized 2-D simulations using the Weather Research and Forecasting Model (WRF). We will use simulations in which the growth of convection is forced by an initial thermal perturbation into conditionally unstable environments with different vertical distributions of specific humidity. We will focus on developing meaningful comparisons between the simulations and the observations provided by TRMM and Kwajalein ground based radar. We will also discuss the possible implications of the sensitivity of the precipitation efficiency in the problem of rainfall estimation from geostationary satellites.
DE: 3310 Clouds and cloud feedbacks
DE: 3329 Mesoscale meteorology
DE: 3354 Precipitation (1854)
SC: Atmospheric Sciences [A]
MN: 2007 Joint Assembly