Evidence of change in the Sea of Okhotsk between 1949-1952 and 1993 from hydrographic data : implications for the North Pacific.
Date
2001
Authors
Hill, Katherine Louise
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Abstract
The Sea of Okhotsk holds substantial importance to North Pacific processes, as it is thought to be the major source region for North Pacific Intermediate water (NPIW). A cruise though this area in 1993, as part of the WOCE project has gone a long way to increasing understanding of the properties and underlying processes. In addition, recent publications have focused on the growing evidence of large-scale changes in water mass properties in the North Atlantic, and more recently, the North Pacific, in which large scale warming and freshening of intermediate waters has been noted. The Sea of Okhotsk is likely to play a key role in such changes due to its role in intermediate water formation.
Recently, ship data from 5 cruises have been made available from the period 1949 to 1952. This provides the opportunity to shed light on the physical properties of this region, and quantify how it has changed over 40 years by comparing this data with the WOCE Pl W cruise. We made two significant conclusions. First, there has been a basin wide warming and freshening of the Sea of Okhotsk. This corroborates other studies suggesting a large scale freshening of intermediate water, attributed to an intensified high latitude hydrological cycle in response to global warming. Second, from salt flux calculations, we concluded that the Sea of Okhotsk was capable of causing the freshening noted in the NPIW over the past half century under certain outflow conditions.