429 Relationship Between Height of Tropical Cyclone Outflow and Entropy Production in the Tropical Cyclone Eyewall Measured during the TCI 2015 Experiment

Tuesday, 24 January 2017
4E (Washington State Convention Center )
Gregory J. Tripoli, Univ. of Wisconsin, Madison, WI

The 2015 TCI experiment conducted by the Office of Naval Research provided an unprecedented set of observations relating hurricane internal eye wall structure and outflow characteristics.  Mecikalski and Tripoli (1998) showed that the intensity of tropical convection is modulated by the environmental resistance to its outflow, resulting from inertial stability, and that convective plumes adjust their structure to take advantage of the outflow path of least resistance.  Recently, Rappin et al, 2011, built on this study to show that the growth rate,  intensity and internal structure of tropical cyclones is similarly affected by the environmental resistance to their outflow resulting from variability of inertial stability in the storm environment, particularly near jet streams .  Based on these results, we constructed an analysis of TC outflow resistance that quantitatively depicts the sector and radial dependence of resistance.

            As the environmental resistance depends on the entropy level and TC storm sector of the outflow, outflow will tend to move into sectors and entropy levels of least resistance.  It follows that the entropy level of the outflow is dependent not only on SST, but also on surface pressure in the eye wall.  Hence we hypothesize that storm intensity may, in turn, have some ability to adjust to the outflow resistance profile.  Moreover, we hypothesize that variation in outflow resistance, such as when a storm recurves poleward, may lead to storm intensity and structure adjustments that take advantage of the changing resistance profiles.

            The 2015 TCI experiment provided an optimal opportunity to test these hypotheses and to make comparisons with predictions of numerical simulations.  Such comparisons will be presented for the 2015 TCI cases of Patricia and Marty in the East Pacific and Joaquin in the Atlantic.

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