WAAS Performance Investigation for Disturbed Ionospheric Conditions over Canadian Latitudes
Bibliographic record
Abstract
The Wide Area Augmentation System (WAAS) now includes four Reference Stations (WRS) in Canada for improved coverage at high latitudes particularly in eastern Canada. Since the number of the stations in the Canadian region is limited, it is possible that some ionospheric irregularities will be undetected and WAAS performance will be degraded. In order to expand the operation of WAAS over Canadian latitudes, WAAS algorithm performance must be evaluated for challenging ionospheric conditions at the Canadian latitudes to ensure that system requirements are met. For this purpose, different scenarios of challenging ionospheric conditions are simulated over the latitudes of interest based on ionospheric features which have been identified as a major challenge for WAAS called Storm Enhanced Density (SED). Archived data from hundreds of Global Positioning System (GPS) stations across Canada and United States are used to study the spatial characteristics of ionospheric Total Electron Content (TEC) variation during many SED events observed at Canadian latitudes. Two-dimensional TEC maps for such events are produced on 2.5o x 2.5o grids using more than 500 GPS stations over North America, and various characteristics are determined: size of the irregularities, magnitude of TEC values inside the plume, and gradients at the edge of the plume. From these simulated conditions, ionospheric delays are estimated for 24 GPS satellites observed from 29 WRSs in Canada and United States. These observations are provided as input to the WAAS algorithm to obtain WAAS estimated ionospheric corrections and associated integrity bounds at ionospheric grid points. Both the current planar fit and future kriging methods are evaluated. Preliminary results indicate that WAAS bounds all ionospheric errors sufficiently; however, as the ionosphere becomes more active, errors in the estimated ionospheric delays become much larger. Also, within the same simulated scenarios, WAAS availability is degraded in regions of undersampling and high gradients, and integrity bounds are increased in these regions. However, WAAS consistently bounds the errors for high ionospheric delay, regions with undersampled threats, and regions of sharp gradients. Due to the lack of stations in the northern and western regions, the ionosphere cannot be monitored over these regions.
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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 | 0.001 | 0.001 |
| 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) | 0.001 | 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".