Water Mass Transformation Induced by Tropical Cyclones

Tropical Cyclones leave heat anomalies within the subsurface layers of the ocean. This heat can be redistributed around the world’s oceans through advection and mixing, and knowing how this heat is being redistributed can help scientists understand heat-driven ocean and atmospheric changes. The goal of this work is to study the subsurface pathways of the anomalies induced by tropical cyclones. We are interested in the salinity, temperature, and surface mixed layer depth changes as they can hold great importance in understanding water masses transformation and their impacts on weather and climate. To achieve this goal, virtual particles were released utilizing the Connectivity Modeling System (CMS), which is an open-source lagrangian model, to simulate the virtual particle dispersal. Particles were released in global ocean-only model experiments from the Community Earth System Model, with and without TC wind forcing, using three different horizontal ocean grid resolutions (high resolution 0.1deg and low-resolution 1deg). These particles were advected for 2 years on the low-resolution model, and for 1.5 years on the high-resolution model to represent the fate of water parcels under direct influence of TCs. The analysis focused on the West Pacific, North Atlantic, and Indian oceans. Results show that some subsurface pathways can lead to cross-basin transport, such that a tropical cyclone in the Indian Ocean might affect the Atlantic, and this influence is enhanced in the high resolution model. Some pathways, specifically in the Western Pacific, followed a pathway to the Equatorial Pacific at about 65m depth. This results in the warming of the Eastern Pacific, which can be a precursor for El Nino events. This is the first large-scale study that focuses on understanding how TCs may influence the transfer of the subsurface heat and salt anomalies throughout the globe, and with this process studied, scientists can better comprehend the remote impacts of TCs in the global ocean.