Flow of pacific water in the western Chukchi Sea: Results from the 2009 RUSALCA expedition

Abstract

The distribution of water masses and their circulation on the western Chukchi Sea shelf are investigated using shipboard data from the Russian-American Long Term Census of the Arctic (RUSALCA) program. Eleven hydrographic/velocity transects were occupied during September of that year, including a number of sections in the vicinity of Wrangel Island and Herald canyon, an area with historically few measurements. We focus on four water masses: Alaskan coastal water (ACW), summer Bering Sea water (BSW), Siberian coastal water (SCW), and remnant Pacific winter water (RWW). In some respects the spatial distributions of these water masses were similar to the patterns found in the historical World Ocean Database, but there were significant differences. Most notably, the ACW and BSW were transposed in Bering Strait, and the ACW was diverted from its normal coastal pathway northwestward through Herald Canyon. It is argued that this was the result of atmospheric forcing. September 2009 was characterized by an abnormally deep Aleutian Low and the presence of the Siberian High, which is normally absent this time of year. This resulted in strong northerly winds during the month, and mooring data from the RUSALCA program reveal that the ACW and BSW were transposed in Bering Strait for a significant portion of the month. Using an idealized numerical model we show that the Ekman response to the wind can cause such a transposition, and that the consequences of this will persist on the shelf long after the winds subside. This can explain the anomalous presence of ACW in Herald Canyon during the RUSALCA survey.

Characteristics and Transformation of Pacific Winter Water on the Chukchi Sea Shelf in Late Spring

“…Chukchi summer water (CSW) is a combination of Anadyr water and central Bering shelf water that mix with each other north of Bering Strait on the southern portion of the shelf (e.g., Gong & Pickart, , ; von Appen & Pickart, ). This water mass has also been referred to as western Chukchi summer water (Shimada et al, ), summer Bering Sea water (Steele et al, ), and Bering Summer Water (Pisareva et al, ). The second Pacific‐origin summer water is the Alaskan coastal water (ACW), which is warmer, fresher, and more strongly stratified than CSW.…”

Seasonal variation of the Beaufort shelfbreak jet and its relationship to Arctic cetacean occurrence

“…Using all 4 years of mooring data, we have constructed a histogram in temperature‐salinity ( T‐S ) space showing the occurrence of the different water masses throughout water column (Figure a). The bounding values of temperature and salinity that define the water mass types are indicated in the figure, although the reader should realize that these boundaries are imprecise (e.g., they can change slightly from year to year [ Pisareva et al ., ]). In addition to the Pacific water and AW, the mooring measured meltwater during parts of the year.…”

Post-glacial flooding of the Bering Land Bridge dated to 11 cal ka BP based on new geophysical and sediment records

“…This value is lower than the 477 years derived for neighboring core 2-PC1 because of the greater water depth at the site. The rationale behind this is that Atlantic-sourced waters are at times present on the northern Chukchi shelf and upwell into the deeper section of Herald Canyon (Pickart et al, 2010;Pisareva et al, 2015), resulting in a lower radiocarbon reservoir age.…”