Morphology of the tropopause layer and lower stratosphere above a tropical cyclone: A case study on cyclone Davina (1999)

During the APE-THESEO mission in the Indian Ocean the M-55 stratospheric research aircraft performed a flight over and in the inner core region of the tropical cyclone Davina. Measurements of total water, water vapour, temperature, aerosol backscattering, ozone and trace gases were made and are here discussed in comparison with averages of those quantities acquired during the campaign timeframe. Temperature anomalies in the TTL, warmer than average in the lower part and colder than averages in the upper part of the TTL were observed; Ozone was strongly reduced compared to its average value, and thick cirrus decks were present up to the cold point, sometimes topped by layer of very dry air. Evidences for meridional transport of trace gases in the stratosphere above the cyclone, and perturbed water distribution in the Tropical Tropopause Layer, are illustrated.