PRECIPITATION BIAS FROM DUAL EL NIÑO SOUTHERN OSCILLATION AND INDIAN OCEAN DIPOLE INTERACTION
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Authors
Brock, Clayton M., Jr.
Subjects
El Nino Southern Oscillation
ENSO
Madden Julian Oscillation
Indian Ocean Dipole
IOD
ENSO
Madden Julian Oscillation
Indian Ocean Dipole
IOD
Advisors
Nuss, Wendell A.
Date of Issue
2025-03
Date
Publisher
Monterey, CA; Naval Postgraduate School
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Abstract
During the winter season of 2023-2024 the Maritime Continent (MC) experienced both the influence of the El Niño phase of the El Niño Southern Oscillation (ENSO) and the positive phase of the Indian Ocean Dipole (IOD), which are both subsidence creating climate drivers that limit rainfall. The NCEP/DOE reanalysis II model, however, determined that there was a positive anomaly of precipitation during the winter season despite the active climate drivers. This leads us to question whether the model was correct and if something in the environment occurred to bring such an anomaly. Utilizing observed satellite data, we determined that rainfall was far less than what the model was outputting. We also found, however, with the use of observed upper air soundings that the model characterized the vertical structure correctly when compared to upper air soundings. At the end of this investigation, we found that the diurnal variability of precipitation was not well represented by the reanalysis, therefore creating amplitude biases that made the environment of the MC precipitation heavy. This led us to conclude that there may have been misrepresentation in reanalysis to capture the environment during the dual ENSO and IOD event, and that further inquiry in the model’s parameterizations are required.
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Distribution Statement
Distribution Statement A. Approved for public release: Distribution is unlimited.
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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.