Performance of conventional and mass-flux PBL schemes for simulating three modes of cloud-boundary layer coupling over the Southern Ocean
Bibliographic record
Abstract
Planetary boundary layer (PBL) structure over the ocean and the model capability to simulate such structure are less well-understood than their counterparts over land. In this study, observations and WRF simulations are examined to study the boundary layer structure over the Southern Ocean, focusing on the coupling between the oceanic boundary layer and the cloud layer above. Based on the lower tropospheric vertical profiles and cross-sections, three cloud-boundary layer coupling modes are identified including a coupled mode with a weak positive surface heat flux (type 1), and two decoupled modes in the presence of either a negative surface heat flux driving a shallow stable boundary layer (type 2) or a strong positive surface heat flux (type 3). Numerical simulations are conducted for representative cases of each mode using the conventional YSU PBL scheme without and with the cloud-induced top-down mixing option (referred to as YSUtopdown), as well as the MYNN and the MYNN eddy-diffusivity mass-flux scheme (MYNN-EDMF) that adopts a holistic treatment of mixed-layer thermals and shallow convective clouds. The MYNN-EDMF scheme offers the best representation of the decoupled type 3 mode where its capability to simulate different vertical extents of local mixing and nonlocal mass flux is found to be essential. Two key parameters in MYNN-EDMF dictating shallow cloud formation are also identified. The YSUtopdown scheme develops deeper boundary layer than the YSU scheme and exhibits more consistency with observations for the coupled type 1 mode. For the decoupled type 2 mode, all four schemes perform similarly well.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".