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ALBSA: Aleutian Low - Beaufort Sea Anticyclone

ALBSA is a 4-point index combining two orthogonal 850 mb differences (one meridional, one zonal). Collectively, this captures the variability in the North Pacific/Pacific Arctic tropospheric circulation quite well. The purpose is to track the juxtaposition of the Aleutian Low and Beaufort High pressure centers, specifically the strength/position of the former and the meridional dipole associated with the latter. This is useful because the index is sensitive to advection events from the north pacific into the Arctic and also how the pattern of circulation steers that advection. It captures the variability of the NPI, and also includes information specific to the advection across Alaska and up through the Bering Strait, and the East Siberian/Chukchi/Beaufort Seas. To date, it has been evaluated during the springtime transition to better understand how the regional circulation impacts the spatial-temporal characteristics of snowmelt timing and onset of melt over sea ice of the Pacific Arctic.


Time Interval: Monthly and Daily
Time Coverage: 1948 to present
Update Status: Static

Get Data:


Data is available from NOAA/ESRL PSL using the NCEP/NCAR Reanalysis. It is updated daily and monthly. Method o

Calculation method:

The index is calculated using 4 points from the NCEP/NCAR Reanalysis Dataset: 850mb geopotential height at

N: 75 N, 170 W
S: 50 N, 170 W
E: 55 N, 150 W
W: 55 N, 200 W (160 E)

ALBSA = [E - W] - [N - S]

References and More Information:

  1. Cox, C. J., Stone, R. S., Douglas, D. C., Stanitski, D. M., & Gallagher, M. R. (2019). The Aleutian Low‐ Beaufort Sea Anticyclone: A climate index correlated with the timing of springtime melt in the Pacific Arctic cryosphere. Geophysical Research Letters, 46, 7464– 7473.
  2. Variations and Trends of the Pacific Arctic Climate and Environmental Response from Robert Stone at NOAA/ESRL GMD.
  3. Poster: The Role of Atmospheric Circulation in the Seasonal Melt of Snow and Sea Ice in the Pacific Arctic..J. Cox1 R.S. Stone D.C. Douglas and D. Stanitski.