Previous UV Bulletin

UV bulletins are short reports on current UV levels at NSF network locations. They are posted bi-weekly between September and December when the "ozone hole" is affecting UV levels at our Austral sites.

Bulletin 6/2006, issued 12/13/06
Reporting period: 11/28/06 - 12/13/06

Synopsis:
The ozone hole has substantially decreased in size and depth during the last two weeks. As of this writing, pockets of ozone-depleted air still exist and can lead to marked increases in UV when they are located over network sites. Record UV levels were observed at McMurdo Station on 12/2/06 when total ozone dropped to 190 DU. The UV Index was 7.5. Similar increases in UV were measured at Palmer Station and Ushuaia between 12/8/06 and 12/10/06 when remnants of the ozone hole passed over the two sites. UV intensities at the South were above the long-term mean until 12/3/06, and remained close to the mean thereafter.

McMurdo Station, Antarctica:
McMurdo Station was affected by the ozone hole between 11/30/06 and 12/2/06. On 12/2/06, total ozone dropped to 190 DU and record UV intensities were observed. The noontime UV Index of this day was 7.5. This value is equal within the measurement uncertainty to the historic maximum UV Index for McMurdo, observed on 11/28/98. After 12/4/06, total ozone was above 300 DU and UV intensities remained moderate. The UV Index stayed below 4.

Palmer Station, Antarctica:
Between 11/29/06 and 12/6/06, the ozone hole did not affect Palmer Station and UV intensities were moderate. The maximum daily UV Index for this week ranged between 3 and 6.5. The mean value calculated from measurements of the last 17 years is 5.8, but UV Indices as high as 14 have been observed historically during the first week of December. Between 12/8/06 and 12/10/06, remnants of the ozone hole passed over the Station and led to spikes in UV. The maximum daily UV Index measured on 12/8/06 was 8.7.

South Pole, Antarctica:
South Pole Station was affected by the ozone hole until 12/3/06. UV intensities were above the long-term mean, calculated from measurements of the last 16 years. The UV Index ranged between 2.5 and 3; historic mean and maximum are 2.4 and 3.8, respectively. After 12/3/06, the ozone hole moved away from the South Pole and total ozone was between 240 and 320 DU. UV levels were close to the historic mean for this period. The UV Index was about 2.

Due to low solar elevations at the South Pole, UV levels are generally smaller than at the Antarctic coast. However, human exposure to UV radiation is significant even for UV Indices below 3, due to radiation reflected off snow.

Ushuaia, Argentina:
Ushuaia was located outside the area of the ozone hole during the entire period. However, between 12/8/06 and 12/10/06, total ozone dropped to values below 270 DU when pockets of ozone-depleted air moved over the tip of South America. UV levels peaked on 12/10/06; the maximum daily UV Index on this day was 9.6. For the remainder of the period UV intensities were moderate to high, with the maximum daily UV Index ranging between 4 and 8. The long-term average UV Index for the first week of December is 6.3, but UV Indices as high as 11 have been observed historically.

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