Publication Abstracts

Igel et al. 2022

Igel, A.L., H. Morrison, S.P. Santos, and M. van Lier-Walqui, 2022: Limitations of separate cloud and rain categories in parameterizing collision-coalescence for bulk microphysics schemes. J. Adv. Model. Earth Syst., 14, no. 6, e2022MS003039, doi:10.1029/2022MS003039.

Warm rain collision-coalescence has been persistently difficult to parameterize in bulk microphysics schemes. We use a flexible bulk microphysics scheme with bin scheme process parameterizations, called AMP, to investigate reasons for the difficulty. AMP is configured in a variety of ways to mimic bulk schemes and is compared to simulations with the bin scheme upon which AMP is built. We find that an important limitation in traditional bulk schemes is the use of separate cloud and rain categories. When the drop size distribution is instead represented by a continuous distribution , the simulation of cloud-to-rain conversion is substantially improved. We also find large sensitivity to the threshold size to distinguish cloud and rain in traditional schemes; substantial improvement is found by decreasing the threshold from 40 to 25 µm. Neither the use of an assumed functional form for the size distribution nor the choice of predicted distribution moments has a large impact on the ability of AMP to simulate rain production. When predicting four total moments of the liquid drop size distribution, either with a traditional two-category, two-moment scheme with a reduced size threshold, or a four-moment single-category scheme, errors in the evolution of mass and the cloud size distribution are similar, but the single-category scheme has a substantially better representation of the rain size distribution. Optimal moment combinations for the single-category approach are investigated and appear to be linked more to the information content they provide for constraining the size distributions than to their correlation with collision-coalescence rates.

Export citation: [ BibTeX ] [ RIS ]

BibTeX Citation

@article{ig04000e,
  author={Igel, A. L. and Morrison, H. and Santos, S. P. and van Lier-Walqui, M.},
  title={Limitations of separate cloud and rain categories in parameterizing collision-coalescence for bulk microphysics schemes},
  year={2022},
  journal={J. Adv. Model. Earth Syst.},
  volume={14},
  number={6},
  pages={e2022MS003039},
  doi={10.1029/2022MS003039},
}

[ Close ]

RIS Citation

TY  - JOUR
ID  - ig04000e
AU  - Igel, A. L.
AU  - Morrison, H.
AU  - Santos, S. P.
AU  - van Lier-Walqui, M.
PY  - 2022
TI  - Limitations of separate cloud and rain categories in parameterizing collision-coalescence for bulk microphysics schemes
JA  - J. Adv. Model. Earth Syst.
VL  - 14
IS  - 6
SP  - e2022MS003039
DO  - 10.1029/2022MS003039
ER  -

[ Close ]

• Return to 2022 Publications

• Return to Publications Homepage