Evolution of the Vertical Temperature Structure in Tropical Cyclones Inferred from GPS Radio Occultation Measurements

Tropical cyclones consist of a self-sustained vortex along with enhanced midlevel convergence into deep convective regions. Past literature has documented tropopause-level cooling above upper tropospheric warming in regions of active deep convection, e.g. within tropical cyclones. The tropopause-level cooling can at least in part be understood as a hydrostatic response to deep convective heating. The relatively large tropospheric heating and balanced circulation of tropical cyclones likely affect the cooling response near the tropopause.

This study focuses on the evolution of temperature anomalies in the upper troposphere and lower stratosphere (UTLS) for intense tropical cyclones. GPS radio occultation measurements from the COSMIC (Constellation Observing System for Meteorology Ionosphere and Climate) satellite constellation are used, which provide high vertical resolution temperature profiles in the UTLS. Storm best tracks from the ATCF (Automated Tropical Cyclone Forecast System) from 2007 to 2014 are used to produce composite evolutions of the vertical temperature structure in tropical cyclones.

Preliminary results confirm the expected middle and upper tropospheric warm anomaly up to 3 K and the tropopause-level cold anomaly of similar magnitude. The temporal evolution of this signal provides new insights into tropical cyclone dynamics and how they influence their environment, in particular circulations near the tropopause.