Environmental and inner-core vertical shear TC impacts
Mark DeMaria (NOAA/NHC)
Numerous previous studies have shown that vertical shear plays a significant role in modulating the structure and intensity of tropical cyclones. However, nearly all of those earlier studies have either employed estimates of vertical shear deduced from large-scale global analyses or to a lesser extent estimates within the inner-core with few if any of those studies seeking to examine the relationship between the large-scale and inner-core shear estimates. Thus, comparisons between airborne Doppler deduced vertical shear estimates and those computed from GFS re-analysis data are currently being conducted to assess how closely related these two measures are and to what extent changes in tropical cyclone structure and intensity can be related to either of these quantities. More specifically, we seek to explore whether the agreement or lack there of between the inner-core and large-scale vertical shear is related to the intensity and structure of a tropical cyclone and to investigate whether it can be shown that either the large-scale or inner-core deduced vertical shear is better correlated with future changes in a tropical cyclone’s structure and intensity.
To accompish our goal comparisons between inner-core NOAA WP-3D airborne Doppler and GFS re-analysis data estimates of vertical shear will be made for approximately ~50 cases for which adequate symmetric inner-core airborne Doppler coverage existed from approximately 2- 9 km altitude. The radial variation of the vertical shear as well as the changes in flow over the depth of the aforementioned layer will be investiagated and the relationship between both measures of vertical shear and changes in TC intensity and structure will be explored.
Reasor, P., R.F. Rogers, and S. Lorsolo, 2013: Environmental flow impacts on tropical cyclone structure diagnosed from airborne Doppler radar composites. Mon. Wea. Rev., 141, 2949-2969.
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