Ocean Climate Conditions during

GLOBEC Northeast Pacific Program (NEP) Long Term Observation Program (LTOP)

Thomas C. Royer and Chester E. Grosch Center for Coastal Physical Oceanography

Old Dominion UniversityNorfolk, VA 23529

andThomas J. Weingartner and Seth Danielson

Institute of Marine Science University of Alaska Fairbanks, AK 99775

email: royer@ccpo.odu.edu

A.Linear Trend Analyses 1997-2003

Variable Slope Probability

Upper Layer (0-100 m) Temp. -0.0330 C/yr. 0.87Lower Layer (100-250m) Temp. -0.0380 C/yr. 0.71Upper Layer Salinity +0.0167 /yr. 0.91Lower Layer Salinity +0.0474 /yr. 1.00

B. Linear Trend Analyses from 1970

Variable Slope Probability

Upper Layer Temp. +0.0315 C/yr. 0.99Lower Layer Temp. +0.0262 C/yr. 0.99Upper Layer Salinity -0.00219 /yr. 0.78Lower Layer Salinity +0.00127 /yr. 0.77Freshwater Discharge +181.7 m3 s-1 yr.-1 0.99Upwelling Index +0.665 m3 s-1 0.98(60 N, 146 W) (100 m)-1 yr.-1

Conclusions

During the GLOBEC Northeast Pacific Long Term Observing Program (LTOP), the nearshore temperatures at GAK1 had a tendency to decrease, reversing the longer term warming.

Overall, since 1970 the water column temperatures at the coast are increasing at a rate of about 0.03 C/year (about 0.9 C for entire record).

During LTOP, the salinities are increasing, reversing a longer term freshening in the upper layer (0-100 m).

Overall, the upper layer salinity at the coast is decreasing (-0.002 /year) while the lower layer salinity (100-250 m) is increasing (+0.001 /year). Stratification is increasing.

Most recently in 2002-3, there was sudden freshening and warming of the water column with the highest water temperatures yet observed since 1970.

•Hydrographic data have been gathered 6-7 times per year across the Seward Line since October 1997 as GLOBEC LTOP.

•We focus here on the first station, adjacent to the coast, GAK1, that has a record that began in 1970.

•The water depth is 263 m and its location is within the Alaska Coastal Current.

Background