The 1998–2000 La Niña in the context of historically strong La Niña events
Bibliographic record
Abstract
Contrary to the impacts ascribed to strong cold El Niño–Southern Oscillation (ENSO) events (La Niña) during the last half of the twentieth century, the 2‐year‐long La Niña during 1998–2000 was accompanied by abnormally warm winter conditions over most of North America. In this study, climate anomalies associated with the 1998–2000 La Niña are compared with the composite of the previous seven strong La Niña events since 1950. Despite the presence of a moderately strong La Niña, analyses of atmospheric circulation and thermal features show that the Pacific–North American sector climate was associated with a zonally elongated ridge in the extratropical North Pacific and warmer‐than‐normal sea surface temperatures (SSTs) in the western tropical Pacific that extended into the North Pacific midlatitudes during 1998–2000 event. Relative to the composite of the previous seven strong La Niñas, anomalous Walker circulation was considerably stronger and shifted westward with the ascending branch of the cell located near 110°E during the 1998–2000 event. This was associated with stronger convection and hence positive precipitation anomalies in the western Pacific. The relationship between SSTs and 500‐hPa geopotential heights over the North Pacific shows that the differences, in thermal and circulation features, between the 1998–2000 La Niña and the seven strong La Niñas bear a close resemblance to a coupled mode of extratropical ocean‐atmosphere variability as revealed by singular value decomposition analysis. This non‐ENSO coupled mode of variability, which relates the interannual variability in SSTs with 500‐hPa heights, was prominent during the winter of 1998–2000. The processes related to this mode are different from those involved in the establishment of extratropical atmospheric circulation and SST anomalies associated with typical La Niña events.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.000 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 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".