Teleconnections Current Weather Current Weather Finish ENSO Finish ENSO North Atlantic and Arctic Oscillations North Atlantic and Arctic Oscillations Pacific Decadal Oscillation Pacific Decadal Oscillation For Next Class: Read Kump et al. Ch. 6

Francou et al. 2004

ENSO Impacts in Central Andes El Niño (warm-phase ENSO) is typically associated with warm and sometimes drier conditions, leading to glacier retreat El Niño (warm-phase ENSO) is typically associated with warm and sometimes drier conditions, leading to glacier retreat low albedo bare ice is exposed to intense tropical sun at higher temperatureslow albedo bare ice is exposed to intense tropical sun at higher temperatures La Niña (cold-phase ENSO) is typically associated with cool and sometimes wetter conditions, leading to glacier advance La Niña (cold-phase ENSO) is typically associated with cool and sometimes wetter conditions, leading to glacier advance high albedo fresh snow covers most glacier surfaces, cloud cover is increased, and temperatures are lowerhigh albedo fresh snow covers most glacier surfaces, cloud cover is increased, and temperatures are lower

© AMS9 Arctic Oscillation Seesaw variation in air pressure between the North Pole and middle latitudes Seesaw variation in air pressure between the North Pole and middle latitudes Associated changes in the horizontal air pressure gradient alter the speed of the band of winds aloft that blows counterclockwise around the ArcticAssociated changes in the horizontal air pressure gradient alter the speed of the band of winds aloft that blows counterclockwise around the Arctic Impacts middle latitude winter weather and contributes to climate variability Impacts middle latitude winter weather and contributes to climate variability Shifts between negative and positive phasesShifts between negative and positive phases

Arctic Oscillation (AO) “An atmospheric circulation pattern in which the atmospheric pressure over the polar regions varies in opposition with that over middle latitudes (about 45 degrees North) on time scales ranging from weeks to decades.” (NSIDC) “An atmospheric circulation pattern in which the atmospheric pressure over the polar regions varies in opposition with that over middle latitudes (about 45 degrees North) on time scales ranging from weeks to decades.” (NSIDC) Also largely synonymous with the North Atlantic Oscillation (NAO)Also largely synonymous with the North Atlantic Oscillation (NAO) Negative AO = colder air over mid-latitudes Negative AO = colder air over mid-latitudes Positive AO = warmer air over mid-latitudes Positive AO = warmer air over mid-latitudes

© AMS11 North Atlantic Oscillation NAO Index varies significantly from one year to the next and from decade to decade NAO Index varies significantly from one year to the next and from decade to decade Record of the North Atlantic Oscillation (NAO) during winter through

Arctic Oscillation (AO) NCDC 2010

Accuweather 2004

Arctic Oscillation /CWlink/daily_ao_index/ao.shtml /CWlink/daily_ao_index/ao.shtml

NOAA 2011

NCDC 2010 Warm-Phase ENSO (El Niño) and Negative Arctic Oscillation (AO) = Moist and Cold 18 Dec 2009

Dec 2009 to Feb 2010 temperature ranked much below normal and precipitation above to much above normal across the southern Appalachian Mountains. 850 hPa Temperature Anomaly

Two highly anomalous periods from 1-13 Jan 2010 and Feb 2010 were particularly important in producing upslope snowfall in the higher elevations and allowing existing snow cover to persist at lower elevations Jan Feb 2010

Numerous stations set new records for days of snow cover. Boone NC: 71 days (mean: 26 days) Mt. LeConte, TN: 115 days (mean: 64 days) 66 days!

Would have missed another 5-10 days if the timing of the storms had been different (i.e., not over holidays or on weekends)

© AMS24 Pacific Decadal Oscillation  Long-lived variation in climate over the North Pacific Ocean and North America SST fluctuate between the north central Pacific Ocean and the west coast of North America SST fluctuate between the north central Pacific Ocean and the west coast of North America  Warm phase SST are lower than usual over the broad central interior of the North Pacific Ocean and above average in a narrow strip along the coasts of Alaska, the Pacific Northwest, and western Canada SST are lower than usual over the broad central interior of the North Pacific Ocean and above average in a narrow strip along the coasts of Alaska, the Pacific Northwest, and western Canada

Pacific Decadal Oscillation “The Pacific Decadal Oscillation (PDO) is a long-lived El Niño-like pattern of Pacific climate variability” (Univ. of Washington 2011) “The Pacific Decadal Oscillation (PDO) is a long-lived El Niño-like pattern of Pacific climate variability” (Univ. of Washington 2011) Decadal variations in Pacific SSTs and sea level pressureDecadal variations in Pacific SSTs and sea level pressure Warm PhaseCool Phase

© AMS26 Pacific Decadal Oscillation  Cool Phase SST are higher in the North Pacific interior and lower along the coast SST are higher in the North Pacific interior and lower along the coast  The strength of the Aleutian low is key to the impact of the PDO  The PDO Index is based on monthly SST anomalies in the North Pacific Ocean, poleward of 20°N

© AMS27 Pacific Decadal Oscillation Variations in the Pacific Decadal Oscillation (PDO) Index between warm phases (positive values) and cool phases (negative values),

Warm Arctic Cold Continents Pattern NSF 2010