TY - JOUR
T1 - New RAMS cloud microphysics parameterization. Part II
T2 - The two-moment scheme
AU - Meyers, Michael P.
AU - Walko, Robert L.
AU - Harrington, Jerry Y.
AU - Cotton, William R.
N1 - Funding Information:
Thanks are extended to Dr. Paul DeMott and Dr. Johannes Verlinde for valuable suggestions. Brenda Thompson helped with the processing of the manuscript. This research was supported under AFOSR Contracts AFOSR-91-0269 and F49620-95-1-0132. The lead author would also like to acknowledge the DOD, AFOSR Contract F49620-92-J-0331M for supporting his graduate research. This research was supported in part by an appointment to the Global Change Distinguished Postdoctoral Fellowships sponsored by the U.S. Department of Energy, Office of Health and Environmental Research, and administered by the Oak Ridge Institute for Science and Education.
PY - 1997/8
Y1 - 1997/8
N2 - This paper is the second in a series of articles describing the new microphysics scheme in the Regional Atmospheric Modeling System (RAMS). In this part, a new two-moment microphysical parameterization is described. The proposed scheme predicts the mixing ratio and number concentration of rain, pristine ice crystals, snow, aggregates, graupel and hail. The general gamma distribution is the basis function used for hydrometeor size in each category. Additional features include: use of stochastic collection for number concentration tendency; breakup of rain droplets formulated into the collection efficiency; diagnosis of ice crystal habit dependent on temperature and saturation; evaporation and melting of each species assuming that the smallest particles completely disappear first; and more complex shedding formulations which take into account the amount of water mass on the coalesced hydrometeor. Preliminary sensitivity testing of the new microphysical scheme in an idealized convective simulation shows that the two-moment prediction scheme allows more flexibility of the size distribution enabling the mean diameter to evolve in contrast to the one-moment scheme. Sensitivity to the prescribed input parameters such as cloud droplet concentrations and the shape parameter ν is demonstrated in the model results.
AB - This paper is the second in a series of articles describing the new microphysics scheme in the Regional Atmospheric Modeling System (RAMS). In this part, a new two-moment microphysical parameterization is described. The proposed scheme predicts the mixing ratio and number concentration of rain, pristine ice crystals, snow, aggregates, graupel and hail. The general gamma distribution is the basis function used for hydrometeor size in each category. Additional features include: use of stochastic collection for number concentration tendency; breakup of rain droplets formulated into the collection efficiency; diagnosis of ice crystal habit dependent on temperature and saturation; evaporation and melting of each species assuming that the smallest particles completely disappear first; and more complex shedding formulations which take into account the amount of water mass on the coalesced hydrometeor. Preliminary sensitivity testing of the new microphysical scheme in an idealized convective simulation shows that the two-moment prediction scheme allows more flexibility of the size distribution enabling the mean diameter to evolve in contrast to the one-moment scheme. Sensitivity to the prescribed input parameters such as cloud droplet concentrations and the shape parameter ν is demonstrated in the model results.
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U2 - 10.1016/S0169-8095(97)00018-5
DO - 10.1016/S0169-8095(97)00018-5
M3 - Article
AN - SCOPUS:0031428710
SN - 0169-8095
VL - 45
SP - 3
EP - 39
JO - Atmospheric Research
JF - Atmospheric Research
IS - 1
ER -