search

E3SM-Project / scream

Fork of E3SM used to develop exascale global atmosphere model written in C++
https://e3sm-project.github.io/scream/
Other
76 stars 55 forks source link

P3: Reconsider adding qcheti to qirim #123

Open hassanbeydoun opened 5 years ago

hassanbeydoun commented 5 years ago

I realize qcheti being added to qirim was part of the original code, but I think we should consider removing it. qcheti represents ice nucleation of cloud drops which in the physical world results in small ice crystals (not rime/graupel).

bartgol commented 4 years ago

Is this still relevant? @AaronDonahue @hassanbeydoun

PeterCaldwell commented 4 years ago

I agree with this argument. In addition to @hassanbeydoun 's opinion, I'd like to know what @JS-WRF-SBM thinks.

JS-WRF-SBM commented 4 years ago

@PeterCaldwell @hassanbeydoun

I think we should ask the same question regarding the frozen droplets (cloud) as well as drops (rain). In principle, frozen species will not lead to 'densification' of particles through riming, but to new particles like ice crystals or graupel (or hail) of various size, depending on the original drop/lets size.

However, P3 distinguishes between 'deposition' and rimed masses contribution, so the total ice mass (per category) is defined by the concept of 2 contributions: qi_tot = qi_dep + qi_rim The 'deposition' portion is treated as unrimed particles, so if we will increase that mass portion alone, the overall bulk density could in principle decrease (based on unrimed m-D relation for large ice crystals), although frozen droplet/drops were just added to this grid-cell ice population -- this is a conceptual contradiction. Therefore, in order to more precisely prognoses the bulk density, both frozen droplets and drops contributes to the rimed mass portion of the total ice mass, which includes correcting the rimed and volume parts of the code.

Overall, I would keep the code intact for this part.