Type of Document	Thesis
Author	Diaz, Dante Christopher
URN	etd-11052007-103739
Title	The Effect of Radiative Transfer on the Atlantic Subtropical Anticyclone and Hurricane Steering
Degree	Master of Science
Department	Meteorology, Department of
Advisory Committee	Advisor Name Title T. N. Krishnamurti Committee Chair Guosheng Liu Committee Member Robert Hart Committee Member
Keywords	Azores High Subtropical High Florida State University Global Spectral Model FSUGSM Bermuda High Tropical Cyclone Tropical Cyclone Steering
Date of Defense	2007-10-25
Availability	unrestricted
Abstract This study explores sensitivity of the Atlantic subtropical anticyclone and the tracks of tropical cyclones traveling around the subtropical anticyclone to radiative transfer. The data sets for these experiments are derived from 120-hours forecasts generated using the T126 version of the Florida State University Global Spectral Model (FSUGSM). The subtropical anticyclone owes its origin, maintenance, and its asymmetrical nature over the Atlantic Ocean mainly due to radiative cooling over the eastern ocean. This being the case, it follows that the way radiative properties are modeled will play a crucial role in determining the reliability of a forecast. In order to examine this, the full FSUGSM is compared to a version with no radiative properties. This represents the most extreme case and shows the significance of radiative properties on not only the subtropical anticyclone, but also the flow associated with it, and thus the tracks of tropical cyclones traversing the Atlantic Ocean. Since the subtropical anticyclone is the dominant factor in the steering flow, it follows that changes in the tropical cyclones’ tracks occur in concert with changes seen in the anticyclone under different radiative conditions. The effects of (no) radiation take about three days to manifest themselves. The subtropical high weakens, and broadens westward without radiative cooling to maintain it. In turn, the orientation of the subtropical high changes as does the steering pattern. Due to this there is a change seen in the tracks of the tropical cyclones. The cyclones are more to the west and south compared to the normal model. Thus, radiation is an important factor in the forecasts of tropical cyclones and their steering environment three days or greater.
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