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Modified JMA ENSO Index and Its Improvements to ENSO Classification

Title: Modified JMA ENSO Index and Its Improvements to ENSO Classification.
Name(s): Keeling, Travis B., author
O’Brien, James J., professor directing thesis
Cunningham, Philip, committee member
Cai, Ming, committee member
Department of Earth, Ocean and Atmospheric Sciences, degree granting department
Florida State University, degree granting institution
Type of Resource: text
Genre: Text
Issuance: monographic
Date Issued: 2009
Publisher: Florida State University
Florida State University
Place of Publication: Tallahassee, Florida
Physical Form: computer
online resource
Extent: 1 online resource
Language(s): English
Abstract/Description: El Nino-Southern Oscillation (ENSO) is a widely known phenomenon that affects many areas including the southeast United States. Over the southeast U.S. the Japan Meteorological Agency (JMA) ENSO index was modified to establish better classifications. In order to properly understand the effects of ENSO on this location a new approach was needed. Spatial resolution was improved by utilization of the PRISM dataset. PRISM provided monthly precipitation and temperature data over the contiguous US at 4 km resolution. Temporal resolution was improved by disregarding the traditional JMA definition of an ENSO year. The new definition requires six consecutive months of 0.5°C anomalies or larger to be listed as an ENSO event. By utilization of this definition, the ENSO index was modified to a monthly index from a yearly index. Many ENSO events begin in the summer months and end before the preceding September, therefore, an adoption of a monthly index is justified. Although several of the effects vary widely over the domain, there are a few prevalent patterns of ENSO effects. During warm phase, from November-April, wet conditions are seen in the coastal areas. July and August are both dry. From fall to spring, Florida and the Atlantic Coast are basically dry, however; the Mississippi River Valley doesn't appear wet as previous studies have indicted. Patterns of temperatures across the southeast are less variable than the precipitation. Differences between the ModJMA and JMA can be seen in several months, especially during late spring and early autumn. This result is not surprising based on the rigid definition of the JMA index. An interesting result presented itself throughout the study. Individual tropical storms can be identified with the increased resolution PRISM data provides. A state by state breakdown of the ModJMA conclusions provides regional summaries. The ModJMA better classifies ENSO periods and leads to a more precise impact of ENSO over the southeast United States.
Identifier: FSU_migr_etd-3246 (IID)
Submitted Note: A Thesis submitted to the Department of Meteorology in partial fulfillment of the requirements for the degree of Master of Science.
Degree Awarded: Spring Semester, 2009.
Date of Defense: October 30, 2008.
Keywords: HCN, Southeastern US, JMA, PRISM, ENSO, COOP, Regional Scale, Tropical Activity, Spring, Summer, ENSO Period, ModJMA
Bibliography Note: Includes bibliographical references.
Advisory Committee: James J. O’Brien, Professor Directing Thesis; Philip Cunningham, Committee Member; Ming Cai, Committee Member.
Subject(s): Meteorology
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Host Institution: FSU

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Keeling, T. B. (2009). Modified JMA ENSO Index and Its Improvements to ENSO Classification. Retrieved from