English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

. The paper describes a switchable parameterization of collisional ice break-up(CIBU), an ice multiplication process that fits in with the two-momentmicrophysical Liquid Ice Multiple Aerosols (LIMA) scheme. The LIMA schemewith three ice types (pristine cloud ice crystals, snow aggregates, andgraupel hail) was developed in the cloud-resolving mesoscale model (Meso-NH).Here, the CIBU parameterization assumes that collisional break-up is mostlyefficient for the small and fragile snow aggregate class of particles whenthey are hit by large, dense graupel particles. The increase of cloud icenumber concentration depends on a prescribed number (or a random number) offragments being produced per collision. This point is discussed andanalytical expressions of the newly contributing CIBU terms in LIMA aregiven. The scheme is run in the cloud-resolving mesoscale model (Meso-NH) to simulatea first case of a three-dimensional deep convective event with heavyproduction of graupel. The consequence of dramatically changing the number offragments produced per collision is investigated by examining the rainfallrates and the changes in small ice concentrations and mass mixing ratios.Many budgets of the ice phase are shown and the sensitivity of CIBU to theinitial concentration of freezing nuclei is explored. The scheme is then tested for another deep convective case where,additionally, the convective available potential energy (CAPE) is varied. Theresults confirm the strong impact of CIBU with up to a 1000-fold increase insmall ice concentrations, a reduction of the rainfall or precipitating area,and an invigoration of the convection with higher cloud tops. Finally, it is concluded that the efficiency of the ice crystal fragmentationneeds to be tuned carefully. The proposed parameterization of CIBU is easy toimplement in any two-moment microphysics scheme. It could be used in thisform to simulate deep tropical cloud systems where anomalously highconcentrations of small ice crystals are suspected.

A representation of the collisional ice break-up process in the two-moment microphysics LIMA v1.0 scheme of Meso-NH