Modeling the impacts of interseasonal to interannual climate variations on tropical cyclone formations in the western North Pacific
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Authors
Johnson, Stephanie A.
Subjects
Advisors
Murphree, Tom
Meyer, David W.
Date of Issue
2011-09
Date
Publisher
Monterey, CA; Naval Postgraduate School
Language
Abstract
We have analyzed the modulation of TC formations in the western North Pacific (WNP) during July-October by El NinÌ o (EN), La NinÌ a (LN), and the Madden Julian Oscillation (MJO). This analysis was conducted from the perspective of several large scale environmental factors (LSEFs) that strongly influence tropical cyclone (TC) formation: sea surface temperature (SST), low level relative vorticity, vertical wind shear, and upper level divergence. We examined the variations in each LSEF associated with EN, LN, and MJO. We used composite LSEFs for EN, LN, and each of the eight MJO phases to force the Naval Postgraduate School (NPS) statistical model for calculating TC formation probabilities. We then compared the resulting probabilities to actual formations to determine how accurately the model represented ENLN and MJO related variations in TC formations. The model based probabilities provide a realistic quantitative representation of how ENLN and MJO make TC formation more and less likely in the WNP. Our results should be useful in improving the education, training, and environmental situational awareness of TC forecasters. Our results also indicate that the NPS model has the potential to improve operational forecasting of TC formations in the WNP, if forced by skillful forecasts of the LSEFs.
Type
Thesis
Description
Series/Report No
Department
Organization
Naval Postgraduate School (U.S.)
Identifiers
NPS Report Number
Sponsors
Funder
Format
xxii, 87 p. : col. maps. ;
Citation
Distribution Statement
Approved for public release; distribution is unlimited.
Rights
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.