An investigation of composite dropsonde profiles for developing and nondeveloping tropical waves during the PREDICT field campaign of 2010

An analysis of mean composite dropsonde profiles for developing and non-developing tropical waves sampled by 26 reconnaissance missions during the Pre-Depression Investigation of Cloud Systems in the Tropics (PREDICT) field campaign of 2010 is presented. Comparisons are made between mean genesis and non-genesis profiles of temperature, mixing ratio, relative humidity, buoyancy, virtual convective available potential energy, and a variety of wind metrics utilized to separate the symmetric from the asymmetric component of wind. Anomalies and statistical significance tests with respect to the mean PREDICT vertical profile and the Dunion (2011) moist tropical sounding are presented. Genesis soundings are further analyzed in temporal progression to investigate whether or not significant changes in the thermodynamic or wind fields occur during the transition from tropical wave to tropical cyclone.

Significant results include the development of positive temperature anomalies from 500-200 hPa two days prior to genesis in developing waves, not observed in the non-genesis mean, corresponding to the development of a warm core. A progressive moistening of the column is observed in the mesoscale within a 100-km radius of the center of circulation approaching genesis, and developing waves are significantly more moist than non-developers four days pre-genesis. There is evidence of a more symmetric mid-level circulation in the wind field for developing cases, while there appears to be anomalous vertical shear in non-developing cases. Finally, and somewhat unexpectedly, convective instability values are much greater for non-genesis than genesis profiles, indicating that greater instability does not necessarily favor greater prospects of genesis.