On Precipitation and Virga over Three Locations during the 1999–2004 Canadian Prairie Drought
Bibliographic record
Abstract
The recent 1999–2004 drought, and especially the period from 2001 to 2002, had major impacts across Canada and in the western Canadian Prairie region in particular. This study characterizes the recent drought with respect to precipitation on a small scale at three sites: Calgary, Edmonton and Saskatoon. Climatologically, precipitation events of low daily accumulation (≤0 mm) account for the majority of the total accumulation (up to 58%) at all study locations. During the recent drought, these events contributed a higher proportion of the total precipitation (up to 63%) because of a lack of heavy precipitation events. Using radar data at these locations, precipitation events were also classified into three categories: convective, stratiform and virga. There was wide variation in the relative importance of stratiform and convective precipitation at the sites with, for example, some drought periods being dominated by convective and others by stratiform events. Virga was also present with an average cloud base temperature <0°C which would have led to efficient sublimational loss contributing to the reduction of precipitation at the surface. Any understanding of drought must take into account such precipitation issues. R ésumé [Traduit par la rédaction] La récente sécheresse de 1999–2004, et plus spécialement la période de 2001 à 2002, a eu des répercussions majeures au Canada en général et dans la région des Prairies canadiennes en particulier. La présente étude caractérise cette sécheresse récente en fonction des précipitation à petite échelle à trois sites : Calgary, Edmonton et Saskatoon. D'un point de vue climatologique, les événements de précipitations de faible accumulation journalière (≤10 mm) comptent pour la majorité de l'accumulation totale (jusqu'à 58 %) à tous les endroits étudiés. Durant la récente sécheresse, ces événements ont constitué une plus grande proportion des précipitations totales (jusqu'à 63 %) à cause du faible nombre d'événements de fortes précipitations. À l'aide des données radar à ces endroits, les événements de précipitation ont aussi été classifiées en trois catégories : convective, stratiforme et virga. Il y a eu une grande variation de l'importance relative des précipitations stratiformes et convectives à ces sites avec, par exemple, certaines périodes de sécheresse dominées par des événements convectifs et d'autres par des événements stratiformes. Il y a eu aussi des virgas avec une température moyenne de la base des nuages <0°C, ce qui aurait causé des pertes par sublimation contribuant à la réduction des précipitations à la surface. Pour comprendre toute sécheresse on doit prendre en compte ce genre de facteurs liés aux précipitations.
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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 | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 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".