Baroclinic Rossby radius of deformation in the southern Baltic Sea

The first baroclinic Rossby radius of deformation (R1) is a fundamental horizontal scale of mesoscale processes. This scale is important for planning both numerical modelling and study areas. R1 was computed on the basis of an 11-year series of high resolution CTD measurements collected during r/v "Oceania" cruises. The data set covered the three main basins of the Baltic Proper: the Bornholm Basin (BB), the Słupsk Furrow (SF) and the Gdańsk Basin (GB). The smallest mean value of R1 was found in the Gdańsk Basin (5.2 km), the largest one in the Bornholm Deep (7.3 km). The seasonal variability of R1 is lower in the western basin than in the eastern one. The seasonal cycle of R1 may be broken by extreme events, e.g. main Baltic inflows (MBI) of saline water. The inflowing water rebuilds the vertical stratification in the southern Baltic Sea and dramatically changes the R1 values. The difference of R1 between a stagnation period and an inflow situation is shown on the basis of observations made during 2002-2003. The main inflow occurred in winter, after ten years of stagnation, and the very low values of R1 (about 4 km) changed to very high ones (more than 9 km). Analysis of stagnation and saltwater inflow events may throw light on the value of R1 in future climatic scenarios. The potential influence of climate change on Baltic Sea salinity, especially a decrease in MBI activity, may change the baroclinic Rossby radius of deformation and the mesoscale dynamics. Values of R1 are expected to be lower in the future climate than those measured nowadays

Freshwater input to the Arctic fjord Hornsund (Svalbard)

Glaciers draining to the Hornsund basin (southern Spitsbergen, Svalbard) have experienced a significant retreat and mass volume loss over the last decades, increasing the input of freshwater into the fjord. An increase in freshwater input can influence fjord hydrology, hydrodynamics, sediment flux and biota, especially in a changing climate. Here, we describe the sources of freshwater supply to the fjord based on glaciological and meteorological data from the period 2006 to 2015. The average freshwater input from land to the Hornsund bay is calculated as 2517 ± 82 Mt a−1, with main contributions from glacier meltwater runoff (986 Mt a−1; 39%) and frontal ablation of tidewater glaciers (634 Mt a−1; 25%). Tidewater glaciers in Hornsund lose ca. 40% of their mass by frontal ablation. The terminus retreat component accounts for ca. 30% of the mass loss by frontal ablation, but it can vary between 17% and 44% depending on oceanological, meteorological and geomorphological factors. The contribution of the total precipitation over land excluding winter snowfall (520 Mt a−1), total precipitation over the fjord area (180 Mt a−1) and melting of the snow cover over unglaciated areas (197 Mt a−1) to the total freshwater input appear to be small: 21%, 7% and 8%, respectively

Estimation of glacial meltwater discharge into Svalbard coastal waters. Oceanologia 39

Abstract During the summer expeditions of r/v 'Oceania' in 1995'Oceania' in -1996, oceanographic investigations comprising CTD profiling and suspension measurements were conducted in Svalbard fjords and shelf waters. The freshwater volume was estimated independently from the salinity drop as compared with the assumed background salinity and from the distribution of mineral suspension density in surface waters. Preliminary calculations of the instantaneous freshwater volume based on the distribution of suspended matter (at depths of < 150 m) yielded a figure of 80 km 3 in Svalbard coastal waters in summer. Values for Hornsund and Kongsfjord ranged from 0.4 to 0.7 km 3 of freshwater at the height of summer. This corresponds well with glaciological estimations, which give an annual discharge of 14.6 to 27.5 km 3 of freshwater for Svalbard. The glacial discharge is estimated to make up some 42% of the freshwater budget of Svalbard shelf waters, the remainder being derived from Barents Sea Arctic waters of reduced salinity

A new ocean dataset describing Boundary Current systems states and their variability

A report on the development and implementations of new methods and dataset productions for Boundary Current systems monitorin

Evolution of the East Greenland Current from Fram Strait to Denmark Strait : synoptic measurements from summer 2012

Author Posting. © American Geophysical Union, 2017. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Oceans 122 (2017): 1974–1994, doi:10.1002/2016JC012228.We present measurements from two shipboard surveys conducted in summer 2012 that sampled the rim current system around the Nordic Seas from Fram Strait to Denmark Strait. The data reveal that, along a portion of the western boundary of the Nordic Seas, the East Greenland Current (EGC) has three distinct components. In addition to the well-known shelfbreak branch, there is an inshore branch on the continental shelf as well as a separate branch offshore of the shelfbreak. The inner branch contributes significantly to the overall freshwater transport of the rim current system, and the outer branch transports a substantial amount of Atlantic-origin Water equatorward. Supplementing our measurements with historical hydrographic data, we argue that the offshore branch is a direct recirculation of the western branch of the West Spitsbergen Current in Fram Strait. The total transport of the shelfbreak EGC (the only branch sampled consistently in all of the sections) decreased toward Denmark Strait. The estimated average transport of dense overflow water (rh > 27.8 kg/m3 and h>08C) in the shelfbreak EGC was 2.860.7 Sv, consistent with previous moored measurements. For the three sections that crossed the entire EGC system the freshwater flux, relative to a salinity of 34.8, ranged from 127613 to 8168 mSv. The hydrographic data reveal that, between Fram Strait and Denmark Strait, the core of the Atlantic-origin Water in the shelfbreak EGC cools and freshens but changes very little in density.Norwegian Research Council Grant Number: 231647; European Union 7th Framework Grant Number: 308299; National Science Foundation Grant Number: OCE-09593812017-09-1

Circulation of the Baltic Sea and its connection to the Pan-Arctic region - a large scale and high-resolution modeling approach

The Baltic Sea has traditionally been considered as a semi-enclosed marginal sea with little or no influence on the adjacent oceans. We employ an eddy-permitting, coupled ice-ocean model of the Pan-Arctic region to study the Baltic Sea, especially its circulation and property exchanges with the North Sea and other regions. Using this high-resolution and large scale model we focus here on the freshwater export from the Baltic Sea and its transport by the Norwegian Coastal Current (NCC) into the Norwegian and Barents Sea. We hypothesize that the freshwater outflow from the Baltic Sea plays a significant role in modification of Atlantic Water properties along its northern pathway from the North Atlantic, through the Nordic Seas, and into the Arctic Ocean. Recommendations are made for more realistic model representation of the Baltic Sea circulation to advance understanding of this region's influence on the large-scale northern polar ocean circulation and climate change