Evaluation of Cloud Microphysics in JMA-NHM Simulations Using Bin or Bulk Microphysical Schemes through Comparison with Cloud Radar Observations

Abstract

Numerical weather prediction (NWP) simulations using the Japan Meteorological Agency Nonhydrostatic Model (JMA-NHM) are conducted for three precipitation events observed by shipborne or spaceborne W-band cloud radars. Spectral bin and single-moment bulk cloud microphysics schemes are employed separately for an intercomparative study. A radar product simulator that is compatible with both microphysics schemes is developed to enable a direct comparison between simulation and observation with respect to the equivalent radar reflectivity factor Ze, Doppler velocity (DV), and path-integrated attenuation (PIA). In general, the bin model simulation shows better agreement with the observed data than the bulk model simulation. The correction of the terminal fall velocities of snowflakes using those of hail further improves the result of the bin model simulation. The results indicate that there are substantial uncertainties in the mass-size and size-terminal fall velocity relations of snowflakes or in the calculation of terminal fall velocity of snow aloft. For the bulk microphysics, the overestimation of Ze is observed as a result of a significant predominance of snow over cloud ice due to substantial deposition growth directly to snow. The DV comparison shows that a correction for the fall velocity of hydrometeors considering a change of particle size should be introduced even in single-moment bulk cloud microphysics.

The JMA Nonhydrostatic Model and Its Applications to Operation and Research

“…Nested simulations were performed for two precipitation events over an area of the East China Sea, where the general features of the horizontal distributions of variables (e.g., effective droplet radius derived from satellite data retrieval) were reproduced. Iguchi et al (2012) evaluated the binbased cloud microphysical scheme through comparison with observation data by shipborne Doppler and spaceborne cloud profiling radars.…”

Representation of microphysical processes in cloud‐resolving models: Spectral (bin) microphysics versus bulk parameterization

“…Further, the method permits the utilization of any type of collision kernel, including kernels in a turbulent flow which vary randomly in space and time [ Pinsky et al , ; Benmoshe et al , ]. These advantages explain its widespread utilization in different versions of BM in the HUCM, as well as in mesoscale cloud‐ resolving models such as WRF (Weather Research Forecasting) [ Khain and Lynn , ; Khain et al , , ], Goddard Cumulus Ensemble (GCE) [ Tao et al , ; Li et al , , ], WRF and SAM (System of Atmospheric Modeling) [ Fan et al , , , , ], WRF and JMA‐NHM (Japan Meteorological Agency Nonhydrostatic Model) [ Iguchi et al , , , , ], SAM [ Ovchinnikov et al , , , ], and RAMS (Regional Atmospheric Mesoscale System) [ Igel and van den Heever , ]. The model acronyms are presented in Table .…”

“…Typically, droplet‐ice collisions are the most important process in the formation of graupel and hail in mixed‐phase convective clouds. In many studies using BM [e.g., Khain and Sednev , ; Khain et al , , ; Fan et al , , , ; Iguchi et al , , Iguchi et al , , ; Ovchinnikov et al , ] the collision kernels between drops and ice particles of different densities are assumed to be equal to those between two spheres of corresponding densities. These kernels were calculated by solving the problem of the hydrodynamic interaction between particles within a wide range of Reynolds numbers [ Khain et al , ].…”

POLARRIS: A POLArimetric Radar Retrieval and Instrument Simulator

“…HUCM SBM is based on a scheme from the HUCM (Khain et al, , , ) and has been tested for a cold‐season snowstorm case (Iguchi, Nakajima, Khain, et al, ), an MC3E midlatitude case (Iguchi, Matsui, Shi, et al, ), and high‐latitude mixed‐phase precipitation events (Iguchi et al, ). The PSD of each hydrometeor category is explicitly calculated over 43 mass bins spanning particle mass sizes from 3.35 × 10 −11 to 1.47 × 10 2 g (ranging from nucleation particles up to centimeter‐scale hail stones).…”