ALBSA: Aleutian Low - Beaufort Sea Anticyclone

Description

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.

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]

Temporal Coverage

• Monthly values: 1948/01 to [an error occurred while processing this directive]
• Update Status: Monthly

Data Notes

Units: standardized