633 A Revisit of the Thermodynamic Structure of Tropical Cylone with GPS Radio Occultation

Tuesday, 9 January 2018
Exhibit Hall 3 (ACC) (Austin, Texas)
Zhen Zeng, UCAR, Boulder, CO; and H. Zhang, S. P. Ho, and S. Sokolovskiy

With a uniform spatial and temporal coverage, GPS radio occultation (RO) measurements are known to be minimally affected by clouds and precipitation, and have been proven promising for monitoring tropical cyclones’ (TC) activity and their thermodynamic structures in previous studies. In this study, by collecting 9-years of available RO data near the TC storms, we re-examine the TC structures by compositing the RO observations in different ways. Instead of presenting the radius-height structure of temperature and humidity fields, the RO data are organized i) according to the relative distance from the storm center normalized by the radius of maximum surface wind, and also ii) in 2-dimensional (2D) mode, along the storm track and across the storm track. The distribution of RO-derived temperature and humidity demonstrated the existence of mid-upper level warm core and low-level high humidity over the vortex central region. Wavelike structures along the normalized distance are also captured, which might be associated with the typical alternating upward and downward flow pattern in the TC. Five different TC basins (i.e., the North Atlantic, the eastern North Pacific, the western North Pacific, the South Pacific, and the southwest Indian Ocean) are investigated using RO data. The resolved TC structures show good agreement with those from the ECMWF model analyses.
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