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Data Overview

NGA LTER data is hosted by our partner Axiom Data Science. Consequently, it is accessible via a data catalog that is part of the DataONE cyberinfrastructure.

Overview of Current Data Collections

Current research activities generate multiple types of data. For instance, continuing tri-annual cruises measure oceanographic conditions along established transect lines in specific seasons. Additionally, process studies and experiments investigate ecological processes in the Gulf of Alaska and within discrete areas such as the plume of the Copper River. Finally, modeling studies use these data to constrain parameters and validate results.

What You’ll Find in the Data Catalog

The data catalog groups datasets into citations by instrument/parameter type and research team. The data catalog searches according to the contents of the datasets’ metadata. However, the actual contents of the data files are not searched. Therefore, a user can search by keyword or Principal Investigator (PI), but not by station or cruise. 

Searching the data catalog returns a list of dataset citations with their Digital Object Identifiers (DOI). Once you find what you want, the citation link takes you to a page with more information. Then that page provides links to downloadable data and metadata files. For the most part, NGA LTER data files are comma-delimited CSV, and metadata are in ISO format (though older files may have different formats). Individual cruises or years are often in separate files. Pay careful attention to the metadata to learn specifics about each dataset.

Data files have a variety of spatial structures. For instance, sampling at oceanographic stations will produce measurements integrated in depth ranges (biological nets), at 1 dbar intervals (CTD profiles), or at discrete depths (water samples from the CTD rosette’s bottle). Or underway sampling can produce data in locations that vary in time (TSG), discrete observations along transects (seabirds), or sections with depth (Acrobat). As oceanographic data, NGA’s samples are very diverse.

Signature Datasets

Because the diversity of NGA LTER datasets may make them difficult to use in scientific synthesis efforts, we are attempting to provide our data in simpler forms. Currently, these are under development. As they are produced, they will be our Signature Datasets.

Interactive Model Results

Several modeling efforts are underway in connection with NGA LTER. For example, the Gulf of Alaska COBALT hindcast (Hauri et al., 2020) is available to explore via an interactive interface on AOOS’s Gulf of Alaska portal. This model was run for 1980-2013 and includes 100 oceanographic variables, including those important to ocean acidification and climate change. Currently, the GoA-COBALT model is being used to investigate how large scale oscillations like the North Pacific Gyre Oscillation can modulate ocean acidification.

COBALT Hindcast
Gulf of Alaska COBALT hindcast model in AOOS’s Gulf of Alaska portal

Historical Context

Types of Data Available

globec logo

The U.S. GLOBEC Northeast Pacific (NEP CGOA) program focused on salmon and their environment (1997-2004). Those efforts sampled along the Seward Line and other transects. In addition to salmon haul data, GLOBEC datasets include zooplankton counts, CTD station data, and results from phytoplankton growth rate and microzooplankton grazing experiments.

Map of NGA Stations
Map of Northern Gulf of Alaska sampling stations

Between the GLOBEC years and the current LTER program, various projects continued collecting Seward Line data (2005-2017). These datasets include physical properties, nutrients, and chlorophyll collected along the Seward Line for monitoring purposes. NPRB’s Project Search & Database and Gulf Watch’s Environmental Drivers Overview provide information on individual projects, including some final reports.

Additionally, annually deployed moorings and month CTD sampling provide long time series at the station GAK1. Recently, moorings have also been deployed at the GEO mooring location near GAK4.

Additional Archives

While we are working to consolidate these decades of data under the umbrella of NGA LTER, other archives provide data from these historic projects as well. If you prefer to visit the original archives, refer to these links:

AOOS Gulf of Alaska Portal