| Summary: | The National Park Service's Southeast Alaska Network (SEAN) oceanography program's 22 stations span the length of Glacier Bay proper, from just outside the mouth of the Bay to the heads of both the East and West Arms. Generally mid-channel and equidistant, stations capture a range of depths from shallow sills to deep basins, and are located along the gradient from tidewater glaciers and turbid outwash streams to source waters at Icy Strait. Seven core stations are sampled on nine cruises per year to allow description of intra-annual variation, and all 22 stations are occupied during two of these cruises (July and winter) to allow description of inter-annual variation. This sampling design also allows us to detect long-term seasonal and annual trends, and to describe the current year in a historical context. We measure standard oceanographic parameters throughout the water column: temperature, salinity, pressure, photosynthetically active radiation (PAR), optical backscatterance (turbidity), dissolved oxygen, and fluorescence (proxy for chlorophyll-a concentration, an index of primary productivity). The scope and methods are fully explained in the formal monitoring protocol. The monitoring program was initiated by the U.S. Geological Survey (USGS) in 1993 and co-operated each year by USGS and Glacier Bay National Park and Preserve through 2008. In 2009, NPS took on full responsibility for the program. That year, the Southeast Alaska Network initiated a comprehensive update of the program, following recommendations from a 2006 program review, peer-reviewed analyses of the Glacier Bay data, and input from staff at USGS, the National Oceanic and Atmospheric Administration, and several universities. The update resulted in retention of most stations, the addition of one new station, and a temporal shift of the sampling effort away from a quarterly cruise schedule. SEAN also rebuilt the data processing and management system to meet NPS I&M standards and to ensure that all products from raw and validated field data through the protocol and synthesis reports are fully validated and web accessible at http://science.nature.nps.gov/im/units/sean/OC_main.aspx.
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