Coherence and trends of anomalies in Barents Sea hydrographic data and Arctic atmospheric systems

The influence of atmospheric systems on ocean circulation is examined using hydrographic data from the Barents Sea. The Barents Sea plays an important role in the Arctic Ocean's thermohaline structure due to its influence on incoming Atlantic water. Recently, Barents Sea oceanographic data collected by different countries has been compiled into a single data set, The Barents and Kara Seas Oceanographic Data Base (BarKode). Two sections in the southwest Barents Sea that bound the inflowing Norwegian Atlantic Water, sampled in summer and winter, were taken from the data set for this study. Seasonal and interannual changes were computed over the years 1950 to 1995, a time period that includes both positive and negative phases of the atmospheric patterns described by the Arctic Oscillation index. Preliminary results show that Barents Sea waters have annual variations of +/- 1 deg C and +/- .1 psu. The anomalies persist over all months for several years (2 to 5) before changing sign, indicating a large scale forcing of similar time period. Linear trends, correlations between oceanographic properties, and between oceanographic variations and large scale atmospheric patterns were assessed. Both oceanographic sections show similar temporal variations in temperature and salinity, with increased temperatures occurring with increased salinity. However, in 1989 a strong increase in temperature occurred with a strong freshening, indicating a change in the typical pattern. Examination of trends in monthly data show a freshening over all months over the time period being studied. There is a warming trend in both sections in November. The warming may be associated with a trend seen in the the sea level pressure over the Arctic. The lower sea level pressure of the summertime has been extending farther into the fall before increasing to typical wintertime pressure. The results show that there are large interannual changes occurring over the southwestern Barents Sea. Connections between these changes and large scale atmospheric patterns will be discussed.