An article by Andra Whiteside (MIO), Cécile Dupouy (MIO) Awnesh Singh, Philipson Bani, Jing Tan and Robert Frouinpublished in January 2023 in Frontiers in Marine Science
A powerful eruption from the Hunga Tonga-Hunga Ha'apai (HTHH) volcano in the Kingdom of Tonga occurred on 15 January 2022.
The volcanic explosion was enormous, leading many scientists to investigate the impact and scale of the event via satellite observations.
This study describes a new ocean colour signature based on a discoloured water spot created by the HTHH eruption.
The high concentration of chlorophyll-a at the surface, ranging from 0.15 to 2.7 mg.m-3, was not associated with a
to the growth of phytoplankton, but to the basaltic and andesitic ash expelled by the volcano and into the ocean.
volcano and in the ocean, leading to erroneous estimates of Chl-a.
The gradual reduction in light attenuation or the diffuse attenuation coefficient.
for downwelling radiation at 490 nm, Kd(490), was interpreted as being due to the ash sinking into the ocean.
due to the sinking of ash particles over time. It is suggested that due to the high
high porosity of 30-40%, a density close to that of seawater, the ash particles remain in the water.
suspended in the water column for more than 10 days with sustained high values of chlorine content derived by satellite.
high values of satellite-derived Chl-a, Kd(490), and the particle backscatter coefficient at 443 nm.
particles at 443 nm. This is due to the strong attenuation of the light caused by the ash, which reduces the depth of penetration to less than 10 metres.
penetration depth of less than 10 metres during the first period after the eruption
the eruption may have had implications for ecological processes and the
biogeochemical cycles in Tongan waters.
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