Analyzing and improving simulated convective and stratiform properties in high-resolution mesoscale simulations using MC3E and TWP-ICE observations

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Description

Convective and stratiform properties of mesoscale convective systems vary as a function of large-scale environment and thus have varied effects on atmospheric heating distributions that induce large-scale circulation responses. Obtaining similar coverage and partitioning of convective and stratiform regions to those observed has proven difficult in high-resolution mesoscale simulations, despite their increasing usage as accurate targets for GCMs. Several different CRM and LAM mesoscale simulations of a large, intense TWP-ICE MCS show that biases in convective and stratiform properties arise in all simulations due to errors in large-scale environmental properties and convective strength, while the magnitudes of the biases are modulated by differences in microphysics parameterizations. It is unclear how representative these TWP-ICE results are for other MCS cases, and therefore, high-resolution WRF simulations of the April 25th and May 20th MCSs during MC3E are being run and analyzed. Convective and stratiform properties are being compared against observed soundings, surface station data, radar reflectivity, rain rate retrievals, vertical velocity retrievals, and DSD retrievals to establish differences and explore reasons for differences so that simulations can be improved in the context of TWP-ICE findings. Suitable setups have been established for both events that produce mesoscale convective systems that evolve in a manner that is qualitatively similar to the observed systems. The April 25th simulation is very sensitive to model setup, whereas the May 20th simulations is much less sensitive. This is a result of the different forcing mechanisms in the two events. The May 20th squall line is forced by a cold front that usurps a dryline in the late evening, whereas the April 25th elevated convection is initiated more subtly at mid-levels. A suite of simulations varying microphysics parameterizations are being run and analyzed to find microphysical properties that most affect convective and stratiform properties, setups that produce the best agreement with observations, and similarities or differences with errors and biases in TWP-ICE simulations.