Evaluating the performance of high-resolution WRF-ARW simulations on TC intensity change during SAL outbreaks

Saharan Air Layer (SAL) is characterized by a an elevated layer of dry, stable air mass, along with mineral dust, which often affects TC intensity change through the tropical Atlantic. Using high-resolution WRF-ARW modeling, we intend to advance our understating of the interaction between TC and SAL. Two tropical cyclones from the 2003 hurricane season, Fabian and Isabel, will be examined in this study. The reasoning for using these two TC's is based on various factors. The specific availability of GPS dropsondes data is limited to a small amount of TC case studies, with Fabian and Isabel proving to be the most fitting to our study. The close proximity of the initial development of Fabian and Isabel, the small time increment between the development of these two TC's, and variation in their intensification process will prove further beneficial in limiting differences in surrounding environmental conditions as well.

The primary objectives of this research include: 1) To quantify how the SAL's dry air affects TC intensity change through the tropical Atlantic, particularly its thermodynamic and kinematic characteristics; 2) To evaluate the performance of high resolution WRF-ARW modeling on TC intensity change during SAL outbreaks, and 3) To access the impact of the moisture information from the GPS dropsondes on the WRF initial/forecast humidity fields and its forecasts of TC intensity.

As a means of validating these simulations, in situ measurements and satellite data products will be used to evaluate the intensity change characteristics and calculate the differences in thermodynamic and kinematic profiles over regions that our simulations are being performed. The sensitivity experiments will focus on the usage of microphysical schemes as well as GPS dropsondes assimilation.