Changes in distribution of brine waters on the Laptev Sea shelf in 2007

Abstract

[1] Combined salinity and d18 O data from summer 2007 reveal a significant change in brine production in the Laptev Sea relative to summer 1994. The distribution of river water and brine-enriched waters on the Laptev Sea shelf is derived based on mass balance calculations using salinity and d 18O data. While in 1994 maximal influence of brines is seen within bottom waters, in 2007 the influence of brines is highest within the surface layer and only a moderate influence of brines is observed in the bottom layer. In contrast to 2007, salinity and d18 O data from summer 1994 clearly identify a locally formed brine-enriched bottom water mass as mixing end-member between surface layer and inner shelf waters on one side and with higher salinity water from the outer Laptev Sea on the other side. In 2007, the brine-enriched waters are predominantly part of the surface regime, and the mixing endmember between surface layer and outer shelf waters is replaced by a relatively salty bottom water mass. This relatively salty bottom water probably originates from the western Laptev Sea. The inverted distribution of brines in the water column in 2007 relative to 1994 suggests a less effective winter sea ice formation in winter 2006-2007 combined with advection of more saline waters from the western Laptev Sea or the outer shelf precedent to the climatically extreme summer 2007. The observed changes result in an altered export of waters from the Laptev Sea to the Arctic Ocean halocline.

Utility of dissolved barium in distinguishing North American from Eurasian runoff in the Arctic Ocean

“…8a). In summer 2007 "onshore" atmospheric conditions prevailed in the Laotev Sea (Bauch et al, 2010). Such an "onshore" scenario forced by the prevailing wind patterns causes Eurasian river runoff from the Laptev Sea to flow preferably eastwards into the East Siberian Sea instead of leaving the shelf northwards (Guay et al, 2001;Dmitrenko et al, 2005;Zhang et al, 2008;Bauch et al, 2009Bauch et al, , 2011b.…”

“…Our end-members are following Ekwurzel et al (2001) (table 3). The endmember for meteoric water is set to a δ 18 O of −20 ‰ reflecting average meteoric waters in the Arctic Ocean (Bauch et al, 2010). Calculation of PO 4 * by dissolved O 2 is done assuming that the water is not in exchange with the atmosphere.…”

Interannual variability of surface and bottom sediment transport on the Laptev Sea shelf during summer

“…Sampling procedure and data analysis are described in detail by Bauch et al (2010Bauch et al ( , 2013. The combined interpretation of δ 18 O composition of the water and salinity allows for the quantification of the different freshwater contributions in polar regions, i.e.…”

“…Based on measurement precision and range of endmember values, calculated river water fractions are derived within ±1 %. For further details on the method and selection of endmembers refer to Bauch et al (2010).…”

A baseline for the vertical distribution of the stable carbon isotopes of dissolved inorganic carbon (δ13CDIC) in the Arctic Ocean

“…Areas of seasonal ice distribution over the Arctic shelves can also have high biological productivity (e.g., [25,41]. Alterations in the Arctic sea-ice cycle have a considerable hydrographic impact as changes in sea-ice extent and production affect the formation of brines and contribution of sea-ice melt to the water column (e.g., [8]) and all these changes may also impact air-sea exchange. Changes in sea-ice seasonality are also likely to have a dramatic effect on Arctic biological production and communities.…”