Glacier Bay oceanographic monitoring program analysis of observations, 1993–2009

Danielson, Seth

The Glacier Bay oceanographic monitoring data archive period of record (July 1993 to October 2009) is newly re-analyzed in this report. This report is intended to be a comprehensive reference manual for temperature and salinity at each monitoring station location; detailed plots for each station are provided in the Appendices. Mean annual cycles are characterized at all stations and across the water column. These climatologies are used to generate monthly anomalies, which are subsequently evaluated for the presence of long-term trends. Temperature fluctuations appear to be regionally coherent whereas the salinity field exhibits more local variations from one portion of Glacier Bay to another. A few stations exhibit marginally statistically significant trends (at the 95% confidence level) in cooling or freshening over the period of record at some depth levels, but these trends are not representative of the bay waters as a whole. Analysis of the density structure on either side of Sitakaday Narrows suggests that near-bottom water renewal of the central basin occurs most readily between November and May, while intermediate water renewal likely occurs in summer months as well. Comparison of the anomaly time series with large-scale climate indices (PDO, ENSO, NPGO and PNA) indicates that these atmospheric and oceanographic patterns of variability exhibit only weak connection with the variability observed within Glacier Bay. Correlations with variability measured at oceanographic station GAK1 (located in the northern coastal Gulf of Alaska) are similarly weak, suggesting that the location of Glacier Bay measurements are well suited to complement the GAK1 time series in providing an independent perspective on coastal Gulf of Alaska oceanic variability.

Glacier Bay oceanographic monitoring program analysis of observations, 1993–2009

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