Observations and Simulation of Elevated Nocturnal Convection Initiation on 24 June 2015 during PECAN
Bibliographic record
Abstract
Abstract The environment of elevated nocturnal deep convection initiation (CI) on 24 June 2015 is investigated using radiosonde data from the Plains Elevated Convection at Night (PECAN) field experiment and a convection-allowing simulation. Elevated CI occurs around midnight in ascending westerly flow above the northeastern terminus of the nocturnal low-level jet (LLJ) several hundred kilometers poleward of the leading edge of a surface warm front. This CI originates from within preexisting banded altocumulus clouds that are supported by persistent large-scale ascent within the entrance region of a midtropospheric jet streak. Model trajectories calculated backward from convective updraft cores during CI indicate abrupt lifting at the leading edge of the surface front during the late afternoon to altitudes above that of the subsequent southerly LLJ. This air remains significantly subsaturated during northward movement until after several hours of weaker but persistent ascent within the highly elevated westerly airstream during the evening. Unlike in many previous studies of frontal overrunning by the LLJ, strong local drying occurs within the LLJ core. Nevertheless, vertical displacements from persistent mesoscale ascent were sufficient for trajectory air parcels to reach their LFC and sustain deep convection. The mesoscale upward displacement along trajectories is well explained by isentropic upglide associated with frontal overrunning at horizontal distances greater than 100 km from the CI and subsequent mature convection. However, the significant additional mesoscale vertical displacements needed for deep CI to occur in the westerlies above the horizontally convergent ~100-km-wide LLJ terminus region, were associated with local cooling and are not accounted for by steady isentropic upglide.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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 teacher head, 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".