University of Alaska
University of Alaska

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

President Obama at GAK1

A presidential visit to GAK1!


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 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 CTD 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).

View of Rugged Island, to the east of station GAK1. 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.

EVOS HomepageThe 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.

 

Have you heard about the warm water anomalies of 2014 and 2015 in the Gulf of Alaska? This figure shows the water column (0-250m) average temperature anomaly as measured at GAK1:

gak1 temp anomaly

 

Access Data: These data are 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.

GAK1 mooring timeseriesGAK1 mooring anomaly timeseries

GAK1 Time Series

GAK1 Anomalies

Note: Anomalies are computed with respect to the mooring data period of record (2000-2014).

Data Plots:

Mooring Time Series by deployment:

1998 1999-2000 2000-2002 2002-2003 2004-2005 2005-2006 2006-2007 2007-2008 2008-2009 2009-2010 2010-2011 2011-2012 2012-2013 2013-2014

CTD Time Series:

camera

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: Now updated through the end of 2013. 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. 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. See also NPRB funded project #734

View of Cape Aialik, to the soutwest of GAK1.


Publications employing data from the GAK1 Time Series:

If you find the GAK1 time series useful, please let us know! If you do use the GAK1 data in your research, we would appreciate an email so that we can keep this list up to date.

    1. Fedewa, E.J., J. A. Miller and T.P. Hurst, 2015, Pre-settlement processes of northern rock sole (Lepidopsetta polyxystra) in relation to interannual variability in the Gulf of Alaska., J. Sea Res., http://dx.doi.org/10.1016/j.seares.2015.11.008

    2. Kelley, J. 2015, An Examination of Hydrography and Sea Level in the Gulf of Alaska. M.S. Thesis, University of Alaska Fairbanks

    3. Stearns, L. A., G. S. Hamilton, C. J. van der Veen, D. C. Finnegan, S. O'Neel, J. B. Scheick, and D. E. Lawson (2015), Glaciological and marine geological controls on terminus dynamics of Hubbard Glacier, southeast Alaska. J. Geophys. Res. Earth Surf., 120, 1065–1081. doi:10.1002/2014JF003341.

    4. Horning, M., & Mellish, J. A. E. (2014). In cold blood: evidence of Pacific sleeper shark (Somniosus pacificus) predation on Steller sea lions (Eumetopias jubatus) in the Gulf of Alaska. Fishery Bulletin, 112(4), 297-310. doi:10.7755/FB.112.4.6

    5. Munro, A. R., and C. Tide, editors. 2014. Run forecasts and harvest projections for 2014 Alaska salmon fisheries and review of the 2013 season. Alaska Department of Fish and Game, Special Publication No. 14-10, Anchorage.

    6. Wang, Y. H. Xue, F. Chai, Y. Chao, J. Farrara, 2014. A model study of the Copper River plume and its effects on the northern Gulf of Alaska, Ocean Dyn. 64:241-258, doi:10.1007/s10236-013-0684-3

    7. Evans, W., J. T. Mathis, P. Winsor, H. Statscewich, and T. E. Whitledg, 2013. A regression modeling approach for studying carbonate system variability in the northern Gulf of Alaska, J. Geophys. Res. Oceans, 118, 476–489, doi:10.1029/2012JC008246.

    8. Zador, S. (editor) and coauthors, 2013, North Pacific Fishery Management Council Ecosystem Considerations for 2014 for the North Pacific Groundfish Stock Assessment and Fishery Evaluation Report, Resource Ecology and Fisheries Management Division, Alaska Fisheries Science Center, National Marine Fisheries Service, NOAA, Seattle, WA

    9. Eggers, D. M., C. Tide, and A. M. Carroll, editors. 2013. Run forecasts and harvest projections for 2013 Alaska salmon fisheries and review of the 2012 season. Alaska Department of Fish and Game, Special Publication No. 13-03, Anchorage.

    10. Janout, M. A., T. J. Weingartner, and P. J. Stabeno, 2013. Air-sea and oceanic heat flux contributions to the heat budget of the northern Gulf of Alaska shelf, J. Geophys. Res. Oceans, 118, 1807–1820, doi:10.1002/jgrc.20095.

    11. Zador, S. (editor) and coauthors, 2012, North Pacific Fishery Management Council Ecosystem Considerations for 2013 for the North Pacific Groundfish Stock Assessment and Fishery Evaluation Report, Resource Ecology and Fisheries Management Division, Alaska Fisheries Science Center, National Marine Fisheries Service, NOAA, Seattle, WA

    12. Hallmann, N., Schöne, B.R., Irvine, G.V., Burchell, M., Cockelet, E.D., Hilton, M.R., 2011. An improved understanding of the Alaska coastal current: the application of a bivalve growth temperature model to reconstruct freshwater-influenced paleoenvironments. Palaios 26, 346e363.

    13. Chan, P., J. Halfar, B. Williams, S. Hetzinger, R. Steneck, T. Zack, and D. E. Jacob, 2011, Freshening of the Alaska Coastal Current recorded by coralline algal Ba/Ca ratios, J. Geophys. Res., 116, G01032, doi:10.1029/2010JG001548

    14. Zador, S., (editor) and coauthors, 2011. North Pacific Fishery Management Council Ecosystem Considerations for 2012 for the North Pacific Groundfish Stock Assessment and Fishery Evaluation Report, Resource Ecology and Fisheries Management Division, Alaska Fisheries Science Center, National Marine Fisheries Service, NOAA, Seattle, WA

    15. 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.

    16. Bechtol, W.R. and G.H. Kruse. 2010. Factors Affecting Historical Red King Crab Recruitment Around Kodiak Island, Alaska. In: G.H. Kruse, G.L. Eckert, R.J. Foy, R.N. Lipcius, B. Sainte-Marie, D.L. Stram, and D. Woodby (eds.), Biology and Management of Exploited Crab Populations under Climate Change. Alaska Sea Grant, University of Alaska Fairbanks. doi:10.4027/bmecpcc.2010.18

    17. Zador, S. and S. Gaichas (editors) and coauthors, 2010. North Pacific Fishery Management Council Ecosystem Considerations for 2011 for the North Pacific Groundfish Stock Assessment and Fishery Evaluation Report, Resource Ecology and Fisheries Management Division, Alaska Fisheries Science Center, National Marine Fisheries Service, NOAA, Seattle, WA

    18. Boldt, J., and S. Zador (editors) and coauthors, 2009. North Pacific Fishery Management Council Ecosystem Considerations for 2010 for the North Pacific Groundfish Stock Assessment and Fishery Evaluation Report, Resource Ecology and Fisheries Management Division, Alaska Fisheries Science Center, National Marine Fisheries Service, NOAA, Seattle, WA

    19. Bechtol, W.R., 2009. Abundance, recruitment, and environmental forcing of Kodiak red king crab. University of Alaska Fairbanks, Doctoral dissertation, 205 p

    20. 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.

    21. Boldt, J. (editor) and coauthors, 2008. North Pacific Fishery Management Council Ecosystem Considerations for 2009 for the North Pacific Groundfish Stock Assessment and Fishery Evaluation Report, Resource Ecology and Fisheries Management Division, Alaska Fisheries Science Center, National Marine Fisheries Service, NOAA, Seattle, WA

    22. 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.

    23. Boldt, J. (editor) coauthors, 2007. North Pacific Fishery Management Council Ecosystem Considerations for 2008 for the North Pacific Groundfish Stock Assessment and Fishery Evaluation Report, Resource Ecology and Fisheries Management Division, Alaska Fisheries Science Center, National Marine Fisheries Service, NOAA, Seattle, WA

    24. 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.

    25. 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.

    26. 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

    27. 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

    28. Coyle, K.O., Pinchuk, A.I., 2005. Seasonal cross-shelf distribution of major zooplankton taxa on the northern Gulf of Alaska shelf relative to water mass properties, species depth preferences and vertical migration behavior. Deep Sea Research II 52, 193–216.

    29. 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

    30. 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

    31. 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.

    32. 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

    33. 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.

    34. 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

    35. PICES, 2004. Marine Ecosystems of the North Pacific. PICES Special Publication 1, 280p.

    36. Coyle, K.O., Pinchuk, A.I., 2003. Annual cycle of zooplankton abundance, biomass and production on the northern Gulf of Alaska shelf, October 1997 through October 2000. Fisheries Oceanography 12, 327–338.

    37. 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.

    38. 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

    39. 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

    40. Anderson, P. J., and Piatt, J. F. 1999. Community reorganization in the Gulf of Alaska following ocean climate regime shift. Marine Ecology Progress Series, 189: 117e123

    41. Mueter, F.J., 1999, Spatial and temporal patterns in the Gulf of Alaska groundfish community in relation to the environments, Doctoral dissertation

    42. Collie, J.S., and G.H. Kruse. 1998. Estimating king crab abundance from commercial catch and research survey data. Pages 73-83 in G.S. Jamieson and A. Campbell, editors. Proceedings of the North Pacific Symposium on Invertebrate Stock Assessment and Management. Canadian Special Publication of Fisheries and Aquatic Sciences 125.

    43. 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.

    44. 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.

    45. Royer, T.C. 1993. High-latitude oceanic variability associated with the 18.6-year nodal tide. J. Geop. Res., 98:4639-4644.

    46. 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.

    47. Xiong, Q. and T.C. Royer. 1984. Coastal temperature and salinity in the northern Gulf of Alaska, J. Geop. Res., 89:8061-8066.


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

 

 

Seth L. Danielson
Research Assistant Professor
Institute of Marine Science
School of Fisheries and Ocean Sciences
Room 112 O'Neill Building
University of Alaska Fairbanks
Fairbanks, AK 99775-7220
Phone: (907) 474-7834
sldanielson@alaska.edu

 

 


Photos taken at station GAK1 by Seth Danielson, August 2001.