FY 1999

Decadal variability in the Aleutian low and its relation to high-latitude circulation

Overland, J.E., J.M. Adams, and N.A. Bond

J. Climate, 12(5), 1542–1548, doi: 10.1175/1520-0442(1999)012<1542:DVOTAL>2 (1999)

The January-February mean central pressure of the Aleutian low is investigated as an index of North Pacific variability in winter on interannual to decadal timescales. Since the turn of the century, 37% of the winter interannual variance of the Aleutian low is on timescales greater than 5 yr. An objective algorithm detects zero crossings of Aleutian low central pressure anomalies in 1925, 1931, 1939, 1947, 1959, 1968, 1976, and 1989. No single midtropospheric teleconnection pattern is sufficient to capture the variance of the Aleutian low. The Aleutian low covaries primarily with the Pacific/North American (PNA) pattern but also with the Arctic Oscillation (AO). The change to a prominent deep Aleutian low after 1977 is seen in indices of both the PNA and AO; the return to average conditions after 1989 was also associated with a change in the AO. The authors' analysis suggests an increasing covariability of the high- and midlatitude atmosphere after 1970.