Insights From a Decade of Research on Coral Reef—Atmosphere Energetics

Abstract

Coral reefs cover approximately 0.10 to 0.25% of the marine environment and yet are home to around 25% of marine species and support the livelihoods of more than 500 million people. They face a wide range of threats, with the impact of global warming gaining most attention due to its frequently claimed causal link to coral bleaching. Here we review a decade of research into the micrometeorology of Heron Reef, a lagoonal platform coral reef in the southern Great Barrier Reef, Australia. Using novel pontoon‐mounted eddy covariance systems, we show that often >80% of net radiation is partitioned into heating the water overlying the reef, the reef benthos, and substrate. Significant spatial variability in energy and trace gas exchanges occurs over the reef in response to different geomorphic and hydrodynamic conditions. Synoptic weather patterns that bring light winds, clear skies, and high humidity, result in reef scale meteorology that appears to have a greater influence on coral bleaching events than the background oceanic warming trend. The reef develops its own convective internal boundary layer, with potential to influence cloud development and therefore the surface energy balance. Knowledge of such local effects is lacking, so it is recommended that future research is needed into reef scale processes and how they interact with larger‐scale forcing.

The Role of Clouds in Coral Bleaching Events Over the Great Barrier Reef

“…This is also a prerequisite for a more quantitative understanding of the ocean heat budget, which would require the consideration of all energy terms including sensible and latent heat fluxes, longwave radiative flux and ocean heat advection, as well as albedo of the reef areas (which depends on local conditions such as coral sand coverage, rubble etc. ), where the incorporation of additional observations and fine‐resolution ocean modeling would be essential (Davis et al., 2011; Garratt & Hyson, 1975; McGowan et al., 2019; Smith, 2001). Our study reveals the important role of local cloud cover in modulating the regional shallow water heat budget across the GBR, particularly over the mid and sub‐tropics, independent of the large‐scale ENSO impact.…”

Modelling the influence of coral-reef-derived dimethylsulfide on the atmosphere of the Great Barrier Reef, Australia

“…This biogenic sulfur source could facilitate nss-SO 4 aerosol nucleation and growth to CCN, increasing the lifetime and albedo of low-level clouds (LLC) over coral reefs (similarly to Charlson et al, 1987). Evaporation over shallow, warm coral reef waters contributes to the formation of a convective boundary layer (~65-130 m), with relatively high humidity and temperature that is favourable for low-level cloud formation (McGowan et al, 2019). It has been hypothesized that DMS emissions facilitate the formation of a local or regional negative feedback within the coral reef boundary layer, shading and cooling the coral reef below (Fischer and Jones, 2012;Jones, 2015;Jones et al, 2017).…”

Coral reefs as a source of climate-active aerosols

“…Reef-scale micrometeorology is an important determinant of the extent and severity of coral bleaching in the GBR ( McGowan & Theobald, 2017 ; McGowan et al, 2019 ). DMS and other volatile biogenic compounds influence aerosol and cloud properties in the remote MBL ( Gabric et al, 2013 ; Fiddes et al, 2018 ; Sanchez et al, 2018 ) and likely play an important role in the local climate of the GBR.…”