Seminar: Dr. Alison Nugent

Please join us as we welcome Dr. Alison Nugent from NCAR, for a seminar titled "Orographic Effects in the Tropics: Wind Speed Control and a Tropical Storm Case Study".Coffee will be served.

Abstract

Mountains around the globe control precipitation patterns and water resources. Here the focus is on understanding orographic precipitation in the tropics over the small island of Dominica. An aircraft dataset from the Dominica Experiment (DOMEX) which took place in the eastern Caribbean is utilized. The aircraft measured upstream and downstream airflow properties as well as the convective clouds and precipitation over the island. These flight data along with an idealized numerical model are used to understand the role of wind speed in controlling the transition from thermally to mechanically forced orographic convection.

In the second part of the presentation, the orographic effects of Dominica on Tropical Storm Erika will be explored. Erika was a weak tropical storm in a sheared environment that passed through the Lesser Antilles on August 27th of 2015. Rain gauges on Dominica measured almost 20 inches of rain in less than 12 hours. Observations and a numerical model are used to investigate the tropical storm structure and storm environment, the effect of Dominica's orography, and other aspects that played a role in the heavy precipitation. Results highlight the multi-scale interactions that can contribute to heavy precipitation associated with tropical cyclone passage near mountainous islands.