2010-2011: The First Northern Hemisphere Ozone Hole in History

For the first time in spring 2011 an ozone hole opened over the northern hemisphere.

Ozone depletion in the Arctic during spring 2011 was unprecedented and an ozone hole similar to that which occurs over Antarctica opened for the first time in the northern hemisphere.  At its peak during March and April, the center of the hole was generally over the Arctic Ocean away from populated areas, however severely low levels of ozone extended into areas over Europe, North America, and Russia.

Scandanavia, the British Isles, and Mainland Europe witnessed staggeringly low levels of ozone on certain days by as much as -34% with average values as low as -20% to -25%.  As the hole drifted over Russia, ozone levels declined to an astonishing -45%.  Values were also low over the United States, to -22%.  This was the first time in history such a dramatic and persistent loss of ozone occured in the northern hemisphere.  In spite of assurances, this was the first Arctic ozone hole and the worst state of the ozone layer in the northern hemisphere ever witnessed.

Press articles warned the population of Sweden to be wary of the returning spring sun since ozone values were staggeringly low.  At times, even with a lower sun angle because of the country's high latitude, enough UV was getting through the hole so that sunlight in Scandanavia was as strong as in the tropics.  Take a moment to picture that, or to feel that rather:

Going to my car the air was nice and cool, but the sun was bright.  I immediately felt the sun stinging my face.  As I drove to work, it just felt impossible to avoid the sun coming in through the windows.  I was stuck in traffic for a bit and couldn't get the sun off my face.  When I got to work I noticed I wasn't the only one with a pink nose and red cheeks.

The Formation of the 2010-2011 Arctic Ozone Hole

Destruction of the ozone layer is caused by certain gases emitted by industry.  While ozone destruction itself cools the stratosphere, a cold stratosphere is needed initially to congregate the gases which are responsible for destroying ozone.  This is why ozone destruction is greater in the high latitudes where the stratosphere is coldest, and is greatest over Antarctica where the stratosphere is even colder.  That is why you used to hear only of a hole over Antarctica.

During the 2010-2011 northern hemisphere winter, temperatures in the Arctic stratosphere were much colder than normal, cold enough that the ozone destruction over the North Pole was more like what is experienced annually over the South Pole.  Record warm surface temperatures in the troposphere were mostly respnosible for the acute period of colder stratosphere temperature.  Greenhouse gas pollution warms the troposhere near the earth's surface, but has an effect of cooling the higher atmosphere.  The 2010-2011 winter was one of the warmest winters ever in the Arctic at the surface

1. Incredibly warm surface temperatures and very abnormal high pressure was present in the Arctic during December and January.  Surface temperatures were record warm.  The 2010 and 2011 winters were the warmest winters in history in the Arctic at the surface.
2. With more heat trapped at the surface less heat by way of radiational cooling was making it to the stratosphere.  Abnormal high pressure and calm weather in the troposphere reduced atmospheric mixing.  Low ozone in the stratosphere is frequently witnessed over high pressure areas in the troposphere since the calmer weather below allows air to stagnante and cool in the stratosphere.
3. The colder than normal temperatures in the Arctic stratosphere allowed for a congregation of gases that destroy ozone more like that in the Antractic where the stratopshere is colder and ozone loss is greater.
4. The return of the spring sun initiated the chemical reactions that destroy ozone.  The first ever Arctic ozone hole opened in March and April.

At the surface, the 2010-2011 winter was one of the warmest ever in the Arctic's history.  A record 500mb geopotential height anomaly occured which indicated the magnitude of the warm high pressure that was present in the troposphere.  Above the persistent calm and warm high pressure, air in the stratosphere was isolated and deprived of heat, allowing temperatures in that layer to fall substantially during the polar night.  Cold in the stratosphere persisted through most of winter as stagnant weather and warm air persisted at the surface.  Stagnant weather patterns and excessive warmth in the troposphere from greenhouse gas pollution makes the stratosphere colder and more prone to ozone depletion.

Ozone Outlook for 2011-2012 as of December 14th . . .

Ozone levels are currently below normal over a widespread area of the northern hemisphere.  Take note that ozone levels may fluctuate as much as 10% daily, so a day with low ozone overhead is not necessarily permanent.  However, areas of depleted ozone from -10% to -15% have been persistent this month and common over populated areas.

Today while driving back to work from the Post Office, I noticed the sky looked warm and bright, and the sun felt much stronger on my face than what I expect at my latitude in December.  Comparatively, the sun did not feel too bad the last few days, so I suspect that ozone was better those days but is lower today.

As for the chance of another Arctic ozone hole following the 2011-2012 winter, though temperatures in the Arctic at the surface are again averaging much warmer than normal, the same atmospheric dynamics in the troposphere will likely not be present since the global heat transfer oscillation is in a different state than last year.  Ozone depletion, seasonally, is usually at its lowest during the end of the winter and beginning of spring so that ozone is already less heading into winter bears watching.

Local Ozone -22% Yesterday

Remember that while ozone in the stratosphere is declining on average there is sometimes a large day-to-day variability in the amount of ozone overhead.  This means some days can feature very low ozone well below the average figure of loss.  Yesterday, locally in the Mid-Atlantic, ozone was down at least 22%.  Under a fair sky, the sun felt blazing, especially with abnormally warm surface temperatures in the 60s.

Notice how "warm" the sky looked, almost like it was a bright summer day.  Surface air temperatures were also abnormally warm this day which aided in light look.  December in the Mid-Atlantic used to be a cold nasty time, yet on this day I felt my face burning while walking my dog on the beach.  Later that afternoon I saw my friend and his father:

Mr C:  How are you?
Me:  Good. Good.
Mr C:  Geez.  How does your face stay so tan?
Me:  [I point up] Well, we're missing part of the ozone layer.

I usually don't get a response to that more than a smile, so I usually change the subject.

Also of note, last week I saw a co-worker who I haven't seen in a while.  Understand that our abnormally warm weather here over the past week has been due to excessive warmth in the troposphere which is not directly caused by the ozone loss.  However, warm weather late in the season tends to keep people outdoors under the sun.  Rick is a hunter:

Rick:  I was sweating in my stand the other day.
Me:  It has been abnormally warm, light southwest winds and a lot of sunshine.
Rick:  Yeah.  I was getting sunburn up there.  It's the end of November!
Me:  Sunburn?  Really?
Rick:  Yeah.  At least it's a little cooler now, but it was like summer up there.
Me:  I don't know if you are aware, but there is a problem with the atmosphere.
Rick:  Shit's messed up.