An Atmospheric Science / Mathematics junior, Jason joined us from the State
University of New York - Albany with a research interest in numerical weather
prediction.
Evidence exists that the recent climate change trend is contributing to the
widening of the tropical belt. Birner (2010) used tropopause statistical
diagnostics to investigate this widening. He concluded that a seasonal cycle
based on these diagnostics could be robust. The tropical belt can also be
defined as the area between the Northern Hemisphere and Southern Hemisphere
subtropical jet streams. A local maximum in the horizontal temperature gradient
near 30deg latitude is a signal of the subtropical jet. Temperature gradient
data was generated from raw data from GPS radio occultations and from four
different reanalysis datasets: ECMWF, NCEP, NCEP-2, and JRA25. Data from Jan
2007 to Dec 2010 was used because of the limited time range of the GPS radio
occultation dataset. The latitude of the subtropical jet in a certain
hemisphere is defined as the latitude that falls at a 20% reduction threshold of
the maximum between 60deg and 0deg. The latitude closest to the equator at this
threshold is considered to be the subtropical jet.
Seasonal variability at 300 mb is shown to be consistent with the
tropopause-based methods in Birner (2010). Seasonal variability patterns for
the tropical belt width at low- and mid-levels (e.g. 700 mb, 500 mb,
respectively.) are shown to be notably different. Most notably, the variability
pattern at the southern edge is shown to differ greatly from the pattern at the
northern edge.
Jason's summer research poster,
Seasonal variability of the width of the tropical belt from GPS radio
occultations and reanalyses, may be found here (2MB).
Jason enjoys watch Buffalo Sabres games, playing Tetris and solving various
different types of puzzles in his free time.
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