Master Thesis Defense by Praifar Intawong

Title: Convective Storm - Analysing Temperature Dependence of Convective Rain in an Idealized Setting

Abstract:
Precipitation extremes has become more frequent, and events dominating extreme precipitation accumulation stems from convective storms, whether they be isolated single cellular storm or multi cellular mesoscale convective systems. In an attempt to understand the effect of the microphysical sensitivity to temperature perturbation in an idealized setting, a simple model has been developed including only primary microphysical processes, and a simple incompressible flow assumption for the dynamical framework.

A two-moment microphysical parameterization is applied, predicting both mass and number density of five hydrometeor types; cloud droplets, raindrops, cloud ice, snow, and graupel. By including processes involving these hydrometeor types contributes to the over all development and shape of the convection cloud and ultimately the temperature.

This model utilizes microphysical processes and atmospheric dynamics to determine accumulated precipitation and the development of liquid water content within clouds, under a vertically uniform variation in the temperature profile. This has shown that increase in temperature with constant relative humidity, also increases the total precipitation and cloud development, but decreases when mixing ratio is held constant.

Furthermore, the convection trigger is investigated, by varying moisture and sensible heat and keeping moist static energy constant in the triggering warm air bubble. This has shown that development of convection favors trigger by sensible heat, compared to trigger by added moisture, which can be a result of the implemented nucleation scheme.

Supervisors: Jens Hesselbjerg Christensen, Nicolas Da Silva (external), Jan Olaf Mirko Haerter (external)
Censor: Peter L. Langen