Maintained by Tom Weingartner, Seth Danielson and David Leech of the Institute of Marine Science at UAF's School of Fisheries and Ocean Science

Located at the mouth of Resurrection Bay near Seward, Alaska, temperature and salinity versus depth profiles have been taken at oceanographic station GAK1 since December, 1970. This multi-decade time series is one of the longest running oceanographic time series in the North Pacific. Long-term means of temperature and density at selected depths show the annual cycle of these two water properties. Monthly mean profiles at the standard depths are shown here, of temperature and salinity. Anomalies of temperature and salinity show interannual variation in the thermohaline structure at GAK1. Salinity, not temperature, is the primary variable that drives the density here in the northern Gulf of Alaska. The annual cycle of salinity closely follows that of density at all depths. GAK1 is the station closest to shore on the Seward Line transect of hydrographic stations, which extends approximately 230 km to the southeast of GAK1. For reference, we provide Gulf of Alaska a large-scale look at the surface current field, annual precipitation rates, and a view of the topographic/bathymetric relief.

For the first 20 years, sampling was accomplished by ships-of-opportunity, primarily research vessels as they left or entered the port, thus the time interval varied from several times per month to several times per year. Since September 1990 the sampling has been accomplished monthly, usually as a single CTD (conductivity-temperature-depth) profile to within 10m of the bottom, 263m. The location is 59° 50.7' N, 149° 28.0' W and is located within the Alaska Coastal Current, so it is well "connected" with the shelf circulation. The platform is the R/V Little Dipper, a 26' vessel. Samples taken between September 1990 and 1996 were sponsored by NOAA's Office of Global Programs (Office of Ocean and Earth Sciences, Ocean Observing Division, Observing Networks Branch) and since that time by the Exxon Valdez Oil Spill Trustees Council.

The first column of the data file is the platform abbreviation and cruise number. The second column is the consecutive station number of the GAK1 cast (a unique identifing number within the ensemble of all casts for the cruise). The time is in decimal years beginning on 1 January. Depth in meters is next followed by temperature (°C), salinity (psu), sigma-t (kg/m³) and dynamic height (dynamic meters).

Until about 1975, the profiling was accomplished with discrete samples using Nansen bottles. Since that time STDs (salinity-temperature-depth) or CTDs have been used. The accuracies of the temperature and salinity are plus/minus 0.02 in °C and PSU. Since parts of the record were discrete samples, we have only used the values at the standard oceanographic depths for this time series, though the other values are available. A summary of the seasonal cycle in these data was published in Xiong and Royer (1984) and the interannual variability was discussed in Royer (1989 and 1993). These data have been used in attempts to explain changes in biological populations of the region (Parker, et al., 1993 and Muter, et al., 1993). It would be helpful to others if you find the data useful and publish using them to notify us to add your reference to those below. We also are interested in knowing non-published uses for the dataset: such feedback helps us maintain the continued support for this long-term dataset.

The sampling has been enhanced by the Exxon Valdez Oil Spill Trustee Council with the addition of a subsurface mooring with temperature and conductivity sensors placed at six depths through the water column. Mooring data is available starting in December, 1997. The EVOS webpage has description of the Gulf Ecosystem Monitoring (GEM) program, online annual reports and other literature employing the use of GAK1 data. Sampling has also been supplemented by the Northeast Pacific GLOBEC program and the North Pacific Reseach Board.

Access Data: These data are open and available for all interested users. If you use the data in your work, please let us know so that we can better demonstrate the utility of this dataset when it comes time to renew funding support.

Data Plots:

Mooring Time Series:

• Deployment 1: March 1998 - December 1998
• Deployment 2: December 1999 - November 2000
• Deployment 3: December 2000 - March 2002
• Deployment 4: April 2002 - September 2003
• Deployment 5: June 2004 - May 2005
• Deployment 6: May 2005 - June 2006
• Summary Plot: Temperature and Salinity 1998-2006

GAK1 Long Term Time Series:

• 2010 Spring and Fall vertical profiles with respect to the long-term mean
• 1970 - 2006 Temperature and Salinity at 30m and 250m
• 1970 to 2010 Anomaly Time Series at standard depths: 0m, 10m, 20m, 30m, 50m, 75m, 100m, 150m, 200m, 250m
  • Red lines indicate the least squares best fit linear trend.

See our new in-development Real-Time Surface Buoy: planned for eventual deployment at GAK1.

GAK1 Photo Gallery

Current and ongoing research utilizing the GAK1 time series includes evaluation of the Gulf of Alaska fresh water and heat budgets. We find that GAK1 can serve to nowcast and hindcast the baroclinic volume transport andthe fresh water content within coastal current (Weingartner et. al., 2005).

Gulf of Alaska Coastal Discharge: data and plots: Updated through the end of 2008. The Discharge Data File contains monthly estimates of the Alaskan Southeast and South Coast runoff, along with the total estimate new Seward and the monthly anomalies. Plots include visualisation of the smoothed discharge, the discharge anomaly and estimates of the discharge plus major Canadian rivers and galacial ablation. For more information on freshwater discharge, the Alaska Coastal Current, and measurements taken in the Northern Gulf of Alaska near station GAK1, see our Cape Fairfield Line homepage. The Pacific Fisheries Environmental Laboratory presents compiled data of the upwelling index for 15 stations along the northern and eastern Pacific Ocean coasts. See also NPRB funded project #734

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• Janout, M. A., T. J. Weingartner, T. C. Royer, and S. L. Danielson, 2010, On the nature of winter cooling and the recent temperature shift on the northern Gulf of Alaska shelf, J. Geophys. Res., 115, C05023, doi:10.1029/2009JC005774.
• Bechtol, W.R., 2009. Abundance, recruitment, and environmental forcing of Kodiak red king crab. University of Alaska Fairbanks, Doctoral dissertation, 205 p
• Tribuzio, C.A.,. 2009. Life history, demography and ecology of the spiny dogfish (Squalus acanthias) in the Gulf of Alaska: Critical information for aiding management. University of Alaska Fairbanks, Doctoral dissertation, in prep.
• Ebbesmeyer, C. C., W. J. Ingraham, T. C. Royer, and C. E. Grosch, 2007, Tub Toys Orbit the Pacific Subarctic Gyre, Eos Trans. AGU, 88(1), 1.
• Sarkar, N., 2007, Mixed layer dynamics along the Seward Line in the northern Gulf of Alaska, Ph.D. dissertation, Old Dominion University, Norfolk, VA, 71p.
• Schroeder, I. D., 2007, Annual and interannual variability in the wind field and hydrography along the Seward Line in the northern Gulf of Alaska, Ph.D. dissertation, Old Dominion University, Norfolk, VA, 81p.
• Royer, T. C. and C. E. Grosch, 2006, Ocean warming and freshening in the northern Gulf of Alaska, Geophysical Research Letters, 33 (16), L16605,doi:10.1029/2006GL026767
• Capotondi, A., M. A. Alexander, C. Deser and A. J. Miller, 2005, Low-Frequency Pycnocline Variability in the Northeast Pacific, Journal of Physical Oceanography, V. 35, 8, 1403-1420
• Ingolfsson, A., 2005, Community structure and zonation patterns of rocky shores at high latitudes: an interocean comparison, Journal of Biogeography, 32(1), 169-182, doi:10.1111/j.1365-2699.2004.01150.x
• Royer, T.C., 2005, Hydrographic responses at a coastal site in the northern Gulf of Alaska to seasonal and interannual forcing, Deep-Sea Research Part II-Topical Studies in Oceanography, 52 (1-2): 267-288
• Sarkar, N, T. C. Royer and C. E. Grosch, 2005. Hydrographic and mixed layer depth variability on the shelf in the northern Gulf of Alaska, 1974-1998.  Cont. Shelf. Res. 25: 2147 – 2162.
• Weingartner, T.J., Danielson, S.L. and Royer, T.C., 2005, Freshwater variability and predictability in the Alaska Coastal Current, Deep-Sea Research Part II-Topical Studies in Oceanography, 52 (1-2): 169-191
• Mueter, F.J., 2004, Gulf of Alaska - Marine Ecosystems of the North Pacific, Vol. PICES Special Publication 1 (pp. 153-175): PICES Special Publication 1.
• Stabeno, P.J., N.A. Bond, A.J. Hermann, N.B. Kachel, C.W. Mordy and J.E. Overland, 2004, Meteorology and oceanography of the Northern Gulf of Alaska, Continental Shelf Research, 24, 859-879
• PICES, 2004. Marine Ecosystems of the North Pacific. PICES Special Publication 1, 280p.
• Committee to Review the Gulf of Alaska Ecosystem Monitoring Program, National Research Council, 2002, A Century of Ecosystem Science - Planning Long-Term Research in the Gulf of Alaska, National Research Council, National Academy Press, Washington, D.C.
• Boldt, J. L. and L. J. Haldorson, 2002 A Bioenergetics Approach to Estimating Consumption of Zooplankton by Juvenile Pink Salmn in Prince William Sound, Alaska, Alaska Fishery Research Bulletin, V9 No. 2, Winter 2002
• Royer, T.C., Grosch, C.E., and Mysak, L.A., 2001, Interdecadal variability of Northeast Pacific coastal freshwater and its implications on biological productivity, Progress in Oceanography, 49 (1-4): 95-111 Sp. Iss. SI
• Mueter, F.J., 1999, Spatial and temporal patterns in the Gulf of Alaska groundfish community in relation to the environments, Doctoral dissertation
• Parker, K.S., T.C. Royer, and R.B. Deriso, 1995. High latitude climate forcing by the 18.6 year lunar nodal cycle and historical recruitment trends in Pacific halibut, Can. Spec. Publ. Fish. Aquat. Sci., 121:447-459.
• Muter, F.J., B.L. Norcross and T.C. Royer, 1994. Do cyclic temperatures cause cyclic fisheries?, Can. Spec. Publ. Fish. Aquat. Sci., 121:119-129.
• Royer, T.C. 1993. High-latitude oceanic variability associated with the 18.6-year nodal tide. J. Geop. Res., 98:4639-4644.
• Royer, T.C. 1989. Upper ocean temperature variability in the Northeast Pacific Ocean: Is it an indicator of global warming? J. Geop. Res., 94:18175-18183.
• Xiong, Q. and T.C. Royer. 1984. Coastal temperature and salinity in the northern Gulf of Alaska, J. Geop. Res., 89:8061-8066.

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Contacts:

Thomas C. Royer Eminent Professor of Oceanography, retired Samuel L. and Fay M. Slover Chair in Oceanography Center for Coastal Physical Oceanography Old Dominion University, Crittenton Hall, 768 West 52nd Street, Norfolk, VA 23529 royer@ccpo.odu.edu	Thomas J. Weingartner Professor Institute of Marine Science School of Fisheries and Ocean Sciences Room 115 O'Neill Building University of Alaska Fairbanks Fairbanks, AK 99775-7220 Phone: (907) 474-7993 weingart@ims.alaska.edu