This thesis investigates the characteristics of the corrections to the initial state of the atmosphere. The technique employed is the key analysis error algorithm, recently developed to estimate the initial state errors responsible for poor short-range to medium-range numerical weather prediction (NWP) forecasts. The main goal of this work is to determine to which extent the initial corrections obtained with this method can be associated with analysis errors. A secondary goal is to understand their dynamics in improving the forecast. / In the first part of the thesis, we examine the realism of the initial corrections obtained from the key analysis error algorithm in terms of dynamical balance and closeness to the observations. The result showed that the initial corrections are strongly out of balance and systematically increase the departure between the control analysis and the observations suggesting that the key analysis error algorithm produced initial corrections that represent more than analysis errors. Significant artificial correction to the initial state seems to be present. / The second part of this work examines a few approaches to isolate the balanced component of the initial corrections from the key analysis error method. The best results were obtained with the nonlinear balance potential vorticity (PV) inversion technique. The removal of the imbalance part of the initial corrections makes the corrected analysis slightly closer to the observations, but remains systematically further away as compared to the control analysis. Thus the balanced part of the key analysis errors cannot justifiably be associated with analysis errors. In light of the results presented, some recommendations to improve the key analysis error algorithm were proposed. / In the third and last part of the thesis, a diagnosis of the evolution of the initial corrections from the key analysis error method is presented using a PV approach. The initial corrections tend to grow rapidly in time and can thus modify significantly the trajectory of a forecast over a relatively short period of time. The results shed light on different mechanisms about the evolution of small and fast growing initial perturbations.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.102484 |
| Date | January 2006 |
| Creators | Caron, Jean-François, 1977- |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Atmospheric and Oceanic Sciences.) |
| Rights | © Jean-François Caron, 2006 |
| Relation | alephsysno: 002572234, proquestno: AAINR27760, Theses scanned by UMI/ProQuest. |
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