Polar cyclone

Polar cyclones (also known as polar vortices, Arctic cyclones, and sub-polar cyclones) are low-pressure areas which strengthen in the winter and weaken in the summer.[1] A polar cyclone is a low pressure weather system usually spanning 1,000–2,000 kilometers (620–1,240 miles) in which the air is circulating in a counter-clockwise fashion (in the northern hemisphere). The reason for the rotation is the same as any other cyclone, the Coriolis effect. One center lies near Baffin Island and the other over northeast Siberia.[2] In the southern hemisphere, it tends to be located near the edge of the Ross ice shelf near 160 west longitude.[3] When the polar vortex is strong, the Westerlies increase in strength. When the polar cyclone is weak, the general flow pattern across mid-latitudes buckles and significant cold outbreaks occur.[4]

Contents

Duration and power

Polar cyclones are climatological features which hover near the poles year-round. They are weaker during summer and strongest during winter. The strength and position of the cyclone shapes the flow pattern across the hemisphere of its influence. An index which is used in the northern hemisphere to gage its magnitude is the Arctic oscillation.[5]

Frequency

Although cyclonic activity is most prevalent in the Eurasian Arctic with approximately 15 cyclones per winter, polar cyclones also occur in Greenland and the Canadian Arctic. Polar cyclones can occur at any time during the year. However, summer cyclones tend to be weaker than winter cyclones.[1] They are not well studied and seldom destructive as they typically take place in sparsely populated areas. The only infrastructure damage that occurs as a direct result of a polar cyclone is to oil and gas rigs present throughout the Antarctic ocean (sometimes known as the Southern ocean). Some cargo and shipping vessels are also affected, although there are minimal or no reports of losses in recent years as the result of a polar cyclone.

Ongoing studies

The Australian and US Federal Governments recently awarded funding for a study into how polar cyclones might influence drought in Australia. Scientists hope that the study will glean valuable insight into why droughts in Southern Australia are getting worse, and whether or not there is a direct link between polar climate activity, and weather patterns elsewhere. "One of the big problems we have in planning for drought has to do with understanding whether the drought that we are in right now is a climate-change signal or part of a natural cycle. If we want to understand that we need to understand where the rain is coming from." [6] The study is expected to be complete by late 2010.

See also

Cyclones and Anticyclones of the world
Types
Annual anticyclones
Polar high – Siberian High – Azores High (Bermuda/North Atlantic) – North American High (Canadian/Greenland) – South Atlantic High (St.Helena) – North Pacific High – South Pacific High – Scandinavian High – Mascarene High (Indian) – Australian High – Antarctic High
Annual cyclones
Aleutian low (Alaska/Far East Russia) – Icelandic Low – Kona low (Hawaii) – Polar low

References

  1. ^ a b Halldór Björnsson. Global circulation. Retrieved on 2008-06-15.
  2. ^ Glossary of Meteorology. Polar vortex. Retrieved on 15 June 2008.
  3. ^ Rui-Rong Chen, Don L. Boyer, and Lijun Tao. Laboratory Simulation of Atmospheric Motions in the Vicinity of Antarctica. Retrieved on 2008-06-15.
  4. ^ James E. Kloeppel. Stratosheric polar vortex influences winter cold, researchers say. Retrieved on 2008-06-15.
  5. ^ Todd Mitchell (2004). Arctic Oscillation (AO) time series, 1899 - June 2002. University of Washington. Retrieved on 2009-03-02.
  6. ^ ""Australian survey into what effects polar cyclones have on drought in Australia"". http://www.expertguide.com.au/news/article.aspx?ID=572. Retrieved 2008-05-13.