Note that details of the cases are being finalized and will be posted as they become available.
The purpose of this case is to compare approaches to simulate evolution of CCN characteristics due to activation/coalescence scavenging in marine stratocumulus. Activation/coalescence scavenging was indicated as a possible factor in observed transitions from closed to open cell circulation patterns, but computational approaches to cope with CCN processing are rare and untested.
This case will include a kinematic setup where computational schemes can be compared without impacts on cloud dynamics, as well as a dynamic model setup suitable for 2D/3D model simulations. A benchmark solution will be provided for the kinematic case applying 2D warm-rain bin microphysics.
Details of this case can be found here.
Squall lines are an important type of mesoscale convective system that is often associated with severe weather.
The goal of this intercomparison is to investigate interactions between microphysics, cold pool intensity, and low-level environmental wind shear in a squall line, which previous studies have shown can strongly affect surface precipitation, storm structure and dynamics, and propagation. This case is based on a storm that occurred on 20 June, 2007 in central Oklahoma. The squall line was well-observed by a combination of dual-polarization radar, surface disdrometer, and mesonet (a network of surface meteorological observations).
Model simulations are to be conducted in two or three dimensions using a quasi-idealized framework, with the environmental sounding based on pre-storm observations and the storm initiated by inserting a cold pool. Sensitivity tests are proposed to investigate how storm characteristics are affected by changes in cold pool strength under different low-level shears.
Details of this case can be found here.
This case of a mid-latitude deep wave cirrus is derived from in situ and remote sensing observations collected during the recent U.S. Department of Energy (DOE) Small Particles in Cirrus (SPartICus) field campaign.
The objective of this case study is to investigate the microphysical and macrophysical evolution and life cycle of a deep-wave cirrus observed over the ARM Southern Great Plains (SGP) site in Oklahoma and to intercompare simulated cirrus cloud properties and radiative effects among models. Special emphasis is on the contribution of small ice crystals in cirrus and the role of homogeneous and heterogeneous ice nucleation. Simulations are compared and evaluated with in situ aircraft observations and with various ground-based and space-borne remote sensors.
We specifically target at regional scale models, large eddy simulation (LES) models and single column models (SCM) with advanced cloud microphysics schemes such as multi-moment bulk microphysics parameterizations or bin microphysics schemes.
Details of this case can be found here.
The case is based on a mixed-phase stratiform Arctic cloud observed on 26 April 2008 during the flight 31 of the Indirect and Semi-Direct Aerosol Campaign (ISDAC).
The goal of this model intercomparison, designed for large-eddy simulation (LES) and cloud resolving models (CRM) is to assess factors controlling the stability of shallow mixed-phase Arctic clouds and examine the sensitivity of the simulated cloud parameters to ice particle properties, such as ice number concentration, growth rate, sedimentation velocity, etc. Because liquid-ice partitioning is tightly coupled with the intensity of vertical motions, the analysis will specifically target interactions of microphysical and radiative processes with cloud dynamics.
Details of this case can be found here.
This case is a mid-latitude winter cyclone in which an intense frontal system carried warm, moist air from the Pacific Ocean across the mountains of the southern coast of British Columbia, Canada, producing heavy snowfall in the region around Whistler Mountain. Two hours after the onset of precipitation, a rapid cooling at the surface occurred along with the creation of a nearly isothermal layer and a shift of the valley flow from upslope to downslope. The precipitation-induced down-valley flow acted as a secondary surface cold front that further enhanced and prolonged the snowfall. This case was well observed during the experimental research demonstration project of the 2010 Vancouver Olympics.
The primary goal of this study is to examine the sensitivity of the diabatic cooling, and the resulting changes to the low-level flow fields and precipitation, to the details in the treatment of melting snow in the microphysics parameterization. Benchmark experimental configurations will be set up for 1D and 2D quasi-idealized frameworks as well as for a full 3D mesoscale model. Observational data will be provided.
Details of this case can be found here.