Eddy Covariance Measurements of Carbon Dioxide Flux and the Surface Energy Budget over a Tropical Ocean Coast

The tropical coasts, a location exposed to all-year intense solar radiation, contribute greatly to the energy, moisture, and carbon exchanges between the air and the sea where the mechanism and location responsible for enhanced interactions are critical in improving the global carbon and water budget estimates. This work reports and analyzes eddy covariance and meteorological data from an instrumented platform and tower located at the coast of a Malaysian Forest Reserve designated area (5 28'6''N, 100 12'1''E) during the Northeast Monsoon, from November 2015 to January 2016. Diurnal meteorological trends showed that mean global radiation peaked at 700 W m–2 in the afternoon while mean net radiation only reached a maximum of 250 W m–2 due to reflected radiation and heavy clouds; both occurred at approximately 14:00 local time (LT). Two underwater temperature sensors at 0.5 m and 2.5 m beneath the water surface showed that the temperatures did not vary much, 29 - 30C, with the coolest and hottest temperature occurring at 08:00 LT and 16:00 LT, respectively. Calculated heat stored by the water showed that coastal tropical waters released heat at a mean of –200 W m–2 during the night and absorbed heat at a mean of 400 W m–2 during the day with a maximum release of heat at 16:00 LT. Sensible and latent heat fluxes were low, which ranged from 0.5 - 2.5 W m–2 and 5 - 20 W m–2, respectively with the highest latent and sensible heat fluxes occurring at 16:00 LT. This is possibly due to generally weak winds that this location is normally subjected to. Analysis of the carbon dioxide fluxes revealed that this coastal tropical ocean is a weak carbon sink, which ranged from –0.2 to –1.2 µmol m–2 s–1, with the maximum sink occurring concurrently with the highest latent and sensible heat fluxes. More data collection is undergoing, which will allow us to accurately estimate the extent of the energy and carbon storage capacity of the tropical coastal location.