Physics and Dynamics of the Tropical Cyclone Cirrus Canopy

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The proposed work seeks to improve understanding of the dynamics and thermodynamics of tropical cyclones (TCs), with a specific emphasis on hurricanes and tropical storms in the Atlantic Ocean basin, specifically within the upper troposphere/cirrus canopy. The team proposes to elucidate the factors controlling diurnal pulses in convection within the canopy (and possibly rainfall within the TC), which is an interesting and relatively new question within the tropical cyclone research community, and one that may have interesting implications for TC track and intensity forecasts. The team proposes to use a hierarchy of numerical models to investigate the sources and consequences of upper tropospheric stability; especially the use of existing and under-utilized observations from the NASA Global Hawk and NOAA G-IV. This work will involve the training of several graduate students; with a goal to recruit students from underrepresented groups. The societal benefit of this study is through the potential improvements to hurricane track and intensity forecasts. This study seeks to utilize a large set of airborne observations and numerical models to study the physics of high clouds associated with tropical cyclones. The observations comprise under-utilized flight-level turbulence data from the NOAA G-IV aircraft, dropsondes from the G-IV and the NASA Global Hawks. This study will describe the distribution of turbulence, low Richardson number, and multiple tropopause structures in tropical cyclones. The emphasis will be on differences within and beyond the high clouds and with respect to time of day. The study will also evaluate daily variations, with focus on the recently discovered, outward-propagating pulses of high cloudiness.