Mesoscale Enhancement
About Heat Fluxes
Near the air-sea interface, two processes that transfer heat between the ocean and atmosphere are:
- Sensible Heat Flux: A difference between the air temperature and sea surface temperature (SST) leads to a direct transfer of energy.
- Latent Heat Flux: A defecit in the humidity of the air leads to a net evaporation (in the tropics). The phase transition between liquid and gas carries latent heat with it.
In the tropics, heat fluxes between the ocean and atmosphere play a crucial role on virtually every timescale, from supporting mesoscale (convective) systems to larger-scale climatological balances. Heat fluxes can be estimated using a “bulk formula” such as the following for latent heat flux:
\[F_q \equiv C_q U(q - q_s)\]Mesoscale systems can generate large amounts of heat flux in a short time-period. This research project focused on how mesoscale systems can enhance the net heat transfer from the ocean to the atmosphere on larger timescales:
- Intraseasonal scales, where variations in the tropics are largely driven by wind patterns (e.g. the MJO)
- Seasonal scales, where variations are driven by the annual migration of large-scale atmospheric features (e.g. ITCZ, monsoon).
- Interannual scales, where variations in the tropics are driven by well-known air-sea coupled oscillations (e.g. ENSO)
Global Tropical Moored Buoy Array
For this project, I used data from the Global Tropical Moored Buoy Array (GTMBA), managed by the Pacific Marine Environmental Laboratory (PMEL). GTMBA consists of three sub-arrays: TAO/TRITON in the Pacific Ocean, PIRATA in the Atlantic, and RAMA in the Indian Ocean. Combined, there have been 126 buoys deployed and/or currently in use:
Some of these buoys were installed in the 1990s or earlier, providing more than a decade’s worth of high-resolution, hourly measurements across the ocean! This large amount of data allows for some very robust climatological descriptions of tropical heat fluxes to be built.
About this Project
I completed this project through an internship as part of the Hollings Scholarship. The Hollings Scholarship enables students in the geosciences and related fields to complete internships with NOAA employees, and I am very grateful for the opportunity this provided!
My internship was conducted under the mentorship of Michael McPhaden, at PMEL. Mike is the director of the GTMBA, and I am very thankful for his guidance on this project and beyond!