New Zealand's weather service NIWA predicted near-record UV levels for the Southern Hemisphere.
Credit: iStockphoto
SYDNEY: Ultraviolet radiation in the southern hemisphere this summer will be significantly higher than any of the last six years - close to the all-time high of the summer of 1998-1999.
Analysis by the New Zealand National Institute of Water & Atmospheric Research (NIWA) showed spring has been a record low ozone period in the southern hemisphere overall. Springtime ozone amounts in middle (30°-60° S) and high (60°-90° S) latitudes of the southern hemisphere have been lower this year than in any other year since satellite observations began in 1979.
The U.N. World Meteorological Organisation reported that the Antarctic ozone hole reached near-record proportions this year.
NIWA scientist Richard McKenzie said the predicted peak ultraviolet index (UVI) varies from place to place. "Where I'm based at Lauder in Central Otago [on New Zealand's South Island], we expect that the peak UVI will be close to 12, averaged over the five highest UV days in each summer month (December, January, and February)."
A UVI of 12 is classified as 'extreme' by international standards, increasing the risk of damaging sun-burn and skin cancer.
This is about five per cent greater than the corresponding mean over the last few years, and is about 10 per cent higher than when measurements began in the early 1990s." UVI values are expected to be higher in the north than in the south of New Zealand, because ozone levels are lower and the sun reaches higher elevations in the north.
According to McKenzie, NIWA's UVI prediction was based on past statistical correlations between springtime ozone and peak UV radiation measured at Lauder in the following summer.
"The low ozone expected over New Zealand is a consequence of the relatively high concentrations of ozone-depleting chemicals still present in the atmosphere, especially over Antarctica, in combination with a minimum in solar activity associated with the solar cycle and possible unusual transport of ozone in the stratosphere this year," said McKenzie. "We expect that over the decades ahead there will be a slow recovery in ozone."
Minimums in 'solar activity' correspond to the appearance of sunspots and high levels of solar radiation.
The most important variable factor affecting UVI is cloud cover, so the ultimate effect of the low ozone will be strongly influenced by the weather.
For daily UV forecasts for Australia, visit NIWA
with NIWA
