ESS5
Prof. Jin-Yi Yu
Positive NAO Index
•Stronger subtropical
high and a deeper than normal Icelandic low.
•More and stronger
winter storms crossing the Atlantic Ocean on a more northerly track.
•Warm and wet winters
in Europe and in cold and dry winters in northern Canada and Greenland
•The eastern US
experiences mild and wet winter conditions
Negative NAO Index
•Weak subtropical
high and weak Icelandic low.
•Fewer and weaker
winter storms crossing on a more west-east zonal pathway.
•Moist air into the
Mediterranean and cold air to northern Europe
•US east coast
experiences more cold air outbreaks and hence snowy weather conditions.
•Greenland, however,
will have milder winter temperatures
Positive Phase
Negative Phase