Latent Heat Nudging in the Canadian High-Resolution (2.5 km) Regional Deterministic Prediction System
Bibliographic record
Abstract
Abstract This study examines the application of latent heat nudging (LHN) for the assimilation of radar-derived precipitation rates in the 2.5-km High-Resolution Deterministic Prediction System (HRDPS) operated by Environment and Climate Change Canada. One goal of this study is to document the overall impact of applying LHN in the most recent operational implementation of the HRDPS. On average, for 110 forecasts conducted over a 2-month period in 2016, LHN is shown to improve a composite NWP index (measuring the average change in RMSE over many variables and observation types) by ∼1.5% compared to a control experiment with no LHN. For winds between 400 and 100 hPa, reductions in RMSE between 1% and 4% are found for lead times up to 48 h. For precipitation, improvements for lead times up to 6 h are shown. Another goal of this study is to quantify the relative contributions for certain components of the LHN implementation. The features being investigated are the inclusion of LHN within the assimilation cycle, the use of idealized heating profiles and the conservation of relative humidity. The 2-month forecasting experiments are conducted with these components deactivated in turn. By comparing these experiments, it is found that the inclusion of LHN in the assimilation cycle has the largest impact. It is also found that the use of idealized profiles in locations where precipitation is observed but not simulated is a critical aspect of this implementation of LHN. A case study is also provided to illustrate the impact of LHN on altitude winds.
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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) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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".