Reviewer

Hugh Morrison (NCAR)

Road Map

The review should cover the following areas

General Microphysics

• Function of microphysics within a model. Processes handled, conversion rates, fall terms, surface rainfall, etc. Precipitating and non-precipitating particles.
• Range of microphysics sophistication in models. Simple to sophisticated schemes, warm rain, simple-ice, mixed phase, graupel/hail, single and double-moment treatments. Size distribution assumptions. May briefly mention aerosols, chemistry interactions, bin microphysics, cloud fraction schemes for unresolved clouds.
• Dynamic effect of microphysics in rest of model. Latent heating (condensation, evaporation, freezing, melting, sublimation, deposition). Drag forces due to particles.
• Radiative effect of microphysics. Longwave emission and absorption, shortwave reflection (cloud albedo), scattering and absorption in clouds, surface shading. Optical depth of species from size distribution or empirical function of path.
  

Microphysics in Data Assimilation

• Problems related to retrieval of clouds from satellite and radar data. Microphysics must be sophisticated enough to represent the observations well (brightness temperature, reflectivity) in a forward operator. Issues associated with this.
• Problems related to adjoint code. Switches and branches, nonlinearities, and linearization of codes.
• Problems related to uncertainties. Uncertain parameters, e.g. relating to size distribution, fall speeds, process rates, ice nucleation, condensation nuclei, clean and dirty air.
• Model errors and biases related to microphysics parameterization.