Hawke's Bay sunrises infused with afterglow of Tongan eruption

Hawke's Bay Today's head visual journalist Warren Buckland took this sunrise photo this morning.

A series of stunning sunrises and sunsets over Hawke's Bay might be the result of the Tongan volcanic eruption in January according to Niwa scientists.

The National Institute of Water and Atmospheric Research has been fielding inquiries from across the country about particularly vibrant skyscapes just before or after the sun crosses the horizon, known as 'afterglows'.

The phenomenon is thought to be caused by aerosols originating from the plume of gas and ash that was ejected when the Hunga Tonga-Hunga Ha'apai volcano erupted in January.

Ash from the volcanic eruption of the undersea Hunga Tonga-Hunga Ha'apai volcano of January 15 and damage from the subsequent tsunami.

Niwa forecaster Nava Fedaeff said stratospheric aerosols change the way that light scatters.

"Usually when you see a sunrise or sunset, it is the clouds that morph into the most vibrant colours. However, when stratospheric aerosols are present following a volcanic eruption, they scatter and bend the light as the sun dips or rises past the horizon, creating a glow in the sky with hues of blue, purple, and violet," she said.

The Lauder Atmospheric Research Station in Central Otago confirmed to Niwa that they have been detecting unusual spikes in aerosols in the stratosphere, at around 20-25 kilometres above New Zealand.

The orange and red afterglow on Friday morning (in fact, all of this week) has been linked to the Tongan volcano. Photo / Warren Buckland

The aerosols have been dispersing around the globe since the eruption, with concentrations spiking in the New Zealand region since mid-May.

New Zealand previously experienced sunset afterglows for months following the eruption of Philippines volcano Mount Pinatubo in 1991.