News / Research Highlights / Arctic Cyclones: Studying Extreme Weather Events in the Arctic

Arctic Cyclones: Studying Extreme Weather Events in the Arctic

December 8, 2004

Arctic cyclones can be an "extreme" weather event that is of increasing importance in climate change research.   This weather pattern is made up of low pressure polar air currents that move counterclockwise in the Northern Hemisphere, as shown in the satellite image below.   Cyclone activity and frequency at high latitudes can indicate changes in the earth's climate patterns.   They are a mechanism for moving heat and moisture into the Arctic.   Like hurricanes, their tropical counterpart, arctic cyclones exhibit high winds and can lead to other climate conditions.   They can generate snowstorms and blizzards and have already caused increased coastal erosion.   In addition, it is important to study how arctic storms are being affected by the current greenhouse warming trend.  

IARC scientist Xiangdong Zhang and his research group are studying cyclonic activity and noted that high-latitude cyclones occur throughout the year, although winter and summer storms display different characteristics.   During the winter season from October to April, arctic cyclones are stronger and of shorter duration than those that occur during the summer months.   Summer season cyclones from March through September tend to be more numerous, weaker, and longer-lasting than their winter counterparts.  

The researchers created the Cyclone Activity Index (CAI), an identification and tracking system that categorizes cyclones in the region north of 30ºN.   The CAI includes information on cyclone intensity, frequency, and duration (Fig.1).   From the index, they determined that arctic cyclone activity increased during the second half of the 20th century, while there was a decrease in cyclones occurring at midlatitudes between 1960 to the early 1990s.   The study focuses on the polar latitude of 60 º to 90ºN, however, they are also tracking the relationship between storms in the polar area and the midlatitude region from 40º to 60ºN.   This is an important part of their research, since cyclones that affect the Arctic can originate in the polar region as well as in lower latitudes (Fig. 2).   On average, 50 cyclones are generated annually within the polar region, while approximately 17 come from subpolar zones. There are also indications that cyclones moving into the North Atlantic and Eurasian sector from midlatitudes have been increasing.   This suggests that storm patterns may be shifting northward toward the pole.  

Xiangdong Zhang originally became interested in arctic cyclones when he noticed that sea level pressure was decreasing at the same time that cyclonic activity was increasing.   He is also interested in extreme events because of their impact on inhabited areas. Arctic cyclones are a major contributor to temperature fluctuations and high winds.   Increased areas of open water can result in higher waves, flooding, and erosion.   These conditions cause property damage and impact daily life. Extreme weather also affects commercial fishing, shipping, and cruise travel.   During severe storms, sea ice is redistributed and can impact where arctic animals live and hunt.   Redistribution can also cause changes to water salinity and temperature.   These conditions are a global concern, since all countries at high latitudes are affected (Fig. 3).

This research goes beyond earlier studies by evaluating seasonal trends in the areas where Arctic cyclones originate, documenting variations in frequency over a longer time period (1948-2002), and combining data on the frequency and intensity of arctic storms.   The information can be used in computer models that can facilitate a broader understanding of high latitude storm activity.   Arctic cyclone data and computer climate models are an integral part of the ongoing research of the arctic climate system at IARC.   This integrated approach toward reducing uncertainty in arctic climate change prediction includes the study of arctic sea ice, atmosphere and ocean, as well as permafrost and arctic biota.  

 

Fig. 1.     Local and CAI Data (Click on figure for a larger view)
(a) seasonal variations in arctic cyclone activity.
(b) comparison of storms originating at midlatitudes with polar generated storms.
(c) the rise in cyclonic activity in the Arctic from 1948-2002.
(d) intense and weak cycles of cyclone activity from 1948-2002.

Fig. 2. For regions of cyclone activity in the Northern Hemisphere, the Arctic region is defined as 60-90°N and the middle latitude region is defined as 40-60°N.

Fig 3. An extremely large area of open water in the Arctic Ocean during 2003 is shown in the figure. During this period, strong arctic cyclones had a much larger open-water access, resulting in larger waves and more coastal flooding and erosion.   Coastal erosion has become a major concern of arctic coastal communities.