Evaluation of the two‐moment scheme LIMA based on microphysical observations from the HyMeX campaign
Résumé
The goal of this paper is to present and evaluate the new LIMA (Liquid Ice Multiple Aerosols) microphysical scheme, which predicts six water species (water vapor, cloud water, rainwater, primary ice crystals, snow aggregates, and graupel). LIMA uses a two‐moment parameterization for three hydrometeor species (ice crystals, cloud droplets, and raindrops), and is derived from the one‐moment scheme ICE3 used daily in the AROME cloud resolvingoperational model at Météo‐France. In addition, it integrates a prognostic representation of the aerosol population. To evaluate the scheme, we simulate two well‐documented Heavy Precipitation Events from the HyMeX (Hydrological cycle in Mediterranean Experiment) campaign. The LIMA simulations are compared to ICE3 simulations and to a large variety of observations, such as rainfall accumulation from rain gauges, particle size distributions from disdrometers, airborne in‐situ measurements of ice particles and Dual‐Polarization radar variables. The evaluation suggests that the rain mixing ratio prognosed by LIMA is more realistic than that prognosed by ICE3. Comparisons with disdrometers and dual‐polarization radars highlight the better representation of the rain microphysical variability when using LIMA but lead to overpredict raindrops with large diameter. The vertical composition of the convective cells is also improved by the two‐moment ice parameterization in the LIMA scheme, which impacts the contents of the one‐moment parameterized snow and graupel species. This evaluation of LIMA suggests ways to improve the hydrometeors representation, focusing especially on the description of the Particle Size Distributions (PSD) for different water species.