Interactions between the Outflow of Tropical Cyclones Marty and Joaquin as revealed by outflow variability observed by HDSS soundings during the 2015 TCI Experiment

Hurricane Marty formed in the extreme eastern Pacific off the southern west coast of Mexico on 26 September 2015 and briefly reached hurricane status on 28 September 2015. Its outflow streamed strongly to the east-northeast during is mature lifecycle, across the central Gulf of Mexico and into the west Atlantic where hurricane Joaquin was undergoing genesis beginning September 29, but accelerating strongly after October 2, when the outflow of Marty reached the region where Joaquin was undergoing genesis. Numerical simulations suggest a relationship between the low potential vorticity of Marty's injected into the isentropic channels of low outflow resistance that encouraged the rapid growth of Joaquin downstream 4 days later.

IOPs were set up to directly observe the outflows of both Marty and Joaquin during the 2015 TCI field campaign. Using these high frequency HDSS soundings of the outflow and storm cores of both storms, the outflow channels of these storms are compared to each other to determine if they are placing outflow into the same isentropic levels and the potential vorticity characteristics of each outflow channel. Numerical simulations of Marty and Joaquin will be fitted with massless tracers released at the surface and proportional to surface energy flux to track the entropy and potential vorticity plumes of each storm and depict their predicted interaction. The relationship of any predicted interactions to weakened outflow resistance associated with low potential vorticity anomalies will be sought. Observational evidence of their actual interaction will then be gathered from the TCI observations potential vorticity in both the storm outflow and surrounding environment. Our hypothesis is that a low potential vorticity environment existed near the developing Joaquin that was built by the outflow of Marty and which boosted the development of Joaquin. Results of this study will be presented at the oral presentation.