North Of Svalbard Research Articles

Observations of brine plumes below melting Arctic sea ice

Abstract. In sea ice, interconnected pockets and channels of brine are surrounded by fresh ice. Over time, brine is lost by gravity drainage and flushing. The timing of salt release and its interaction with the underlying water can impact subsequent sea ice melt. Turbulence measurements 1 m below melting sea ice north of Svalbard reveal anticorrelated heat and salt fluxes. From the observations, 131 salty plumes descending from the warm sea ice are identified, confirming previous observations from a Svalbard fjord. The plumes are likely triggered by oceanic heat through bottom melt. Calculated over a composite plume, oceanic heat and salt fluxes during the plumes account for 6 and 9 % of the total fluxes, respectively, while only lasting in total 0.5 % of the time. The observed salt flux accumulates to 7.6 kg m−2, indicating nearly full desalination of the ice. Bulk salinity reduction between two nearby ice cores agrees with accumulated salt fluxes to within a factor of 2. The increasing fraction of younger, more saline ice in the Arctic suggests an increase in desalination processes with the transition to the “new Arctic”.

Evidence of Diel Vertical Migration of Mesopelagic Sound-Scattering Organisms in the Arctic

While sound scattering layers have been described previously from ice-covered waters in the Arctic, the existence of a viable mesopelagic community that also includes mesopelagic fishes in the Arctic has been questioned. In addition, it has been hypothesized that vertical migration would hardly exist in these areas. We wanted to check if deep scattering layers (DSLs) was found to the west and north of Svalbard (79°30’N - 82°10’N) during autumn 2015, and if present; whether organisms in such DSLs undertook vertical migrations. Our null hypothesis was that there would be no evidence of diel vertical migration. Multi-frequency acoustic observations by hull mounted echosounders (18, 38 and 120 kHz) revealed a DSL at depths ~210-510 m in areas with bottom depths exceeding ~600 m. Investigating eight geographical locations that differed with respect to time periods, light cycle and sea ice conditions, we show that the deeper layer of DSL displayed a clear ascending movement during night time and a descending movement during daytime. The high-light weighted mean depth (343-514 m) with respect to backscattered energy was statistically deeper than the low-light weighted mean depth (179-437 m) for the locations studied. This behavior of the DSL was found to be consistent both when the sun was continuously above the horizon and after it started to set on 1 September, and both in open water and sea ice covered waters. The weighted mean depth showed an increasing trend, while the nautical area backscattering strength from the DSL showed a decreasing trend from south to north among the studied locations. Hydrographic observations revealed that the diel migration was found in the lower part of the north-flowing Atlantic Water, and was disconnected from the surface water masses above the Atlantic Water during day and night. The organisms conducting vertical migrations were studied by vertical and oblique hauls with zooplankton nets and pelagic trawls. These data suggest that these organisms were mainly various mesopelagic fishes, some few larger fishes, large zooplankton like krill and amphipods, and various gelatinous forms.

Small‐scale sea ice deformation during N‐ICE2015: From compact pack ice to marginal ice zone

AbstractWe studied small‐scale (50 m to 5 km) sea ice deformation from ship radar images recorded during the N‐ICE2015 campaign. The campaign consisted of four consecutive drifting ice stations (Floes 1–4) north of Svalbard, with a total duration of nearly 5 months. Deformation was calculated using 5 different time intervals from 10 min to 24 h, and the deformation rate was found to depend strongly on the time scale. Floes 1–3 had a mean deformation rate within the range of 0.06–0.07 h−1 with the interval of 10 min, and 0.03–0.04 h−1 with the interval of 1 h. Floe 4 represented marginal ice zone (MIZ) with very high deformation rate, 0.14/0.08 h−1 with the interval of 10 min/1 h. Deep in the ice pack, high deformation rates occurred only with high wind and drift speed, while in MIZ they were found also during calm conditions. The deformation rates were found to follow power law scaling with respect to length and time scale even on this small scale and in small domain (15 km × 15 km). The length scale dependence of deformation rate depends on the time scale: the power law scaling exponent β of the whole study period decreases from 0.82 to 0.52 with the time interval increasing from 10 min to 24 h. Ship radar images reveal the importance of the deformation history of the ice pack, since the deformation events were initialized along the lines of previous damages.

How Satellites Can Support the Information Requirements of the Polar Code

In 2000, the International Maritime Organization (IMO) adopted a new requirement for all international and cargo ships exceeding a certain size, and all passenger ships, to carry Automatic Identification System (AIS) transponders capable of providing information about the ship to other ships and to coastal authorities automatically. The requirement became effective for all ships on 31 December 2004. AIS provides other vessels with information about, for example, a ship’s identity, position, course, speed and destination. The IMO is finalizing implementation of the Polar Code for the safety of vessels, which will apply in both polar waters and will require additional information about the profile of the fleets of ships operating there. However it must be noted that the AIS data is generally only available from legitimate operators (for example, licensed fishers, tourist operators and vessels on government service) and if the AIS transponder is turned off, the vessel becomes virtually invisible. This methodology, therefore, is not a stand-alone system. Norway has currently two satellites in polar orbit capable of receiving AIS signals. AIS is an excellent tool to track tourist vessels and as such create situational awareness and assist in search and rescue operations in the Arctic. The paper presents findings from three regions in the High Arctic: east of the coast of Greenland, north of Svalbard and surrounding the Russian archipelago of Franz Joseph Land, for the years 2010 to 2014 about maritime activities in these regions with a focus on passenger and fishing vessels. It also suggests other satellite-based means for verifying the AIS data.

Regional melt-pond fraction and albedo of thin Arctic first-year drift ice in late summer

Abstract. The paper presents a case study of the regional (≈150 km) morphological and optical properties of a relatively thin, 70–90 cm modal thickness, first-year Arctic sea ice pack in an advanced stage of melt. The study combines in situ broadband albedo measurements representative of the four main surface types (bare ice, dark melt ponds, bright melt ponds and open water) and images acquired by a helicopter-borne camera system during ice-survey flights. The data were collected during the 8-day ICE12 drift experiment carried out by the Norwegian Polar Institute in the Arctic, north of Svalbard at 82.3° N, from 26 July to 3 August 2012. A set of > 10 000 classified images covering about 28 km2 revealed a homogeneous melt across the study area with melt-pond coverage of ≈ 0.29 and open-water fraction of ≈ 0.11. A decrease in pond fractions observed in the 30 km marginal ice zone (MIZ) occurred in parallel with an increase in open-water coverage. The moving block bootstrap technique applied to sequences of classified sea-ice images and albedo of the four surface types yielded a regional albedo estimate of 0.37 (0.35; 0.40) and regional sea-ice albedo of 0.44 (0.42; 0.46). Random sampling from the set of classified images allowed assessment of the aggregate scale of at least 0.7 km2 for the study area. For the current setup configuration it implies a minimum set of 300 images to process in order to gain adequate statistics on the state of the ice cover. Variance analysis also emphasized the importance of longer series of in situ albedo measurements conducted for each surface type when performing regional upscaling. The uncertainty in the mean estimates of surface type albedo from in situ measurements contributed up to 95% of the variance of the estimated regional albedo, with the remaining variance resulting from the spatial inhomogeneity of sea-ice cover.

Sea-ice surface roughness estimates from airborne laser scanner and laser altimeter observations in Fram Strait and north of Svalbard

AbstractWe present sea-ice surface roughness estimates, i.e. the standard deviation of relative surface elevation, in the Arctic regions of Fram Strait and the Nansen Basin north of Svalbard acquired by an airborne laser scanner and a single-beam laser altimeter in 2010. We compare the scanner to the altimeter and compare the differences between the two survey regions. We estimate and correct sensor roll from the scanner data using the hyperbolic response of the scanner over a flat surface. Measurement surveys had to be longer than 5 km north of Svalbard and longer than 15 km in Fram Strait before the statistical distribution in surface roughness from the scanner and altimeter became similar. The shape of the surface roughness probability distributions agrees with those of airborne electromagnetic induction measurements of ice thickness. The ice in Fram Strait had a greater mean surface roughness, 0.16 m vs 0.09 m, and a wider distribution in roughness values than the ice in the Nansen Basin. An increase in surface roughness with increasing ice thickness was observed over fast ice found in Fram Strait near the coast of Greenland but not for the drift ice.

中国冬季极端低温事件与海温和海冰的关系

本文利用站点资料和再分析资料分析中国冬季南、北方区域极端低温事件与海温和海冰的关系。研究发现，中国南、北方区域极端低温频数下降趋势与全球变暖有关，极端低温频数的线性趋势与印度洋和北大西洋海温异常呈负相关，还与前期边缘海海冰特别是格陵兰–巴伦支海海冰异常呈正相关。对于北方区域，在年代际变化尺度上，极端低温事件偏多时，冬季北太平洋海温表现为北负南正的异常分布，格陵兰–巴伦支海海冰呈正异常。在年际变化尺度上，冬季北太平洋中部与北美西岸海域海温出现西负东正的异常分布，北美东岸海温表现为负异常，楚科奇海和新瓦尔巴群岛以北海区海冰呈负异常。对南方区域，在年代际变化尺度上，极端低温事件偏多与PDO冷位相有关，并与格陵兰海和白令海海冰异常呈正相关，其他海区海冰异常呈负相关。在年际变化尺度上，前期阿拉斯加湾和白令海海区异常偏冷，对应着冬季南方区域极端低温事件偏多，另外还与冬季太平洋扇区海冰异常存在显著负相关关系。 Based on the dataset of daily minimum temperature in China during 1961-2010 and reanalysis data, the relationship between winter extreme minimum temperature (EMT) frequency and sea surface temperature (SST) and sea ice is analyzed. Research shows that, the decline of EMT fre-quency both in the north and south of China is associated with global warming. The linear trend has a negative correlation with the SST anomalies in the North Atlantic and India Ocean, and can be preceded by melting of the marginal sea ice, especially in the Greenland-Barents Sea ice during the preceding summer and autumn. For the north of China, its inter-decadal (ID) component may be affected by North Pacific SST anomalies which has a north-negative and south-positive distribution, and has a positive correlation with Greenland-Barents sea ice. While inter-annual (IA) component has a significant negative correlation with the SST anomalies along the east coast of North American and the anomalous SST between the subtropical North Pacific Ocean and the Gulf of Alaska represents a distribution of the dipole oscillation. And it is also affected by the sea ice melting in Chukchi Sea and Sea area in the north of Svalbard. On the other hand, for the south of China, its ID component is remarkable influenced by Pacific Decadal Oscillation (PDO). It also has a negative correlation with the marginal sea ice except the Greenland Sea and the Bering Sea. Beyond the IA time scale, the SST anomalies over the Bering Sea and the Gulf of Alaska prelude the anomalous winter EMT in the south of China. In addition, it also has a significant negative correlation with Pacific sector sea ice.

The melt‐freeze cycle of the Arctic Ocean ice cover and its dependence on ocean stratification

[1] A time-dependent, 1-D coupled ice-ocean model is used to quantify the impact of ocean stratification on the Arctic ice cover. The model results show that the ice growth during winter equals the ice melt in summer for areas with a well-developed cold halocline layer (CHL), provided that the initial ice thickness is around 3 m, while thinner initial ice thickness results in net growth. Areas with weak salt stratification can have a negative annual thickness change irrespective of the initial ice thickness and are thus dependent on ice import in order to remain ice covered. The model results also show that ocean stratification is mostly important for ice-thickness development during the growing season. Areas with weak stratification have an ocean heat flux up to 8 W m−2 reaching the ice during the growing season, while areas with a CHL have an average of about 0.7 W m−2. In the extreme area, north of Svalbard, the ocean heat fluxes are typically around 25 W m−2 but can be up to 400 W m−2 during the initial adjustment, when the warm Atlantic water has direct contact with the ice. A general outcome of the study is that, depending on ocean stratification, the ice cover of Arctic Ocean can be divided into one part with net ice growth (the major part) and another part with net ice melt (mainly in the Nansen Basin).

Multi‐instrument observations from Svalbard of a traveling convection vortex, electromagnetic ion cyclotron wave burst, and proton precipitation associated with a bow shock instability

AbstractAn isolated burst of 0.35 Hz electromagnetic ion cyclotron (EMIC) waves was observed at four sites on Svalbard from 0947 to 0954 UT 2 January 2011, roughly 1 h after local noon. This burst was associated with one of a series of ~50 nT magnetic impulses observed at the northernmost stations of the IMAGE magnetometer array. Hankasalmi SuperDARN radar data showed a west‐to‐east (antisunward) propagating vortical ionospheric flow in a region of high spectral width ~ 1–2° north of Svalbard, confirming that this magnetic impulse was the signature of a traveling convection vortex. Ground‐based observations of the Hα line at Longyearbyen indicated proton precipitation at the same time as the EMIC wave burst, and NOAA‐19, which passed over the west coast of Svalbard between 0951 and 0952, observed a clear enhancement of ring current protons at the same latitude. Electron precipitation from this same satellite indicated that the EMIC burst was located on closed field lines, but near to the polar cap boundary. We believe these are the first simultaneous observations of EMIC waves and precipitating energetic protons so near to the boundary of the dayside magnetosphere. Although several spacecraft upstream of Earth observed a steady solar wind and predominantly radial interplanetary magnetic field orientation before and during this event, data from Geotail (near the morning bow shock) showed large reorientations of the interplanetary magnetic field and substantial decreases in ion density several minutes before it, and data from Cluster (near the afternoon bow shock) showed an outward excursion of the bow shock simultaneous with it. These upstream perturbations suggest that a spontaneous hot flow anomaly, a bow shock related instability, may have been responsible for triggering this event, but do not provide enough information to fully characterize that instability.

Organic matter characterization in Barents Sea and eastern Arctic Ocean during summer

The characteristics and distribution of the organic matter (OM) pool were investigated in the northern Barents Sea shelf region and eastern Arctic Ocean in July 2004. The first results on the vertical and horizontal distributions of surface-active substances and folic acid are presented along with dissolved organic carbon (DOC) measurements and sulfur determination, and related to salinity, temperature, and chlorophyll a ( Chl a). Neutral and low acidity substances dominated the surface-active OM pool at all depths and stations investigated. Characterization of hydrophobic/hydrophilic properties of the OM revealed the dominance of more hydrophobic substances in the upper mixed layer and highly hydrophilic substances in deep waters. Electrochemically detectable organically bound sulfur was a minor component compared to the presence of inorganic forms of sulfur, S 2−, S 0, detected in concentrations up to 10 nmol l − 1 . DOC concentrations were more or less uniform in the entire region, while SAS concentrations were elevated in the upper mixed layer. The OM pool was larger in the northern Barents Sea, east of Svalbard, than in the eastern Arctic Ocean station, north of Svalbard.

Respiration, mineralization, and biochemical properties of the particulate matter in the southern Nansen Basin water column in April 1981

Determinations of the activity of the respiratory electron transport system (ETS), during the FRAM III expedition permit us to estimate oxygen utilization rates ( R O 2 ) from the surface to 2000 m under the polar pack ice in the Nansen Basin just north of Svalbard (83°N, 7°E) during April 1981. We found R O 2 at in situ temperatures ranging from 20 pM O 2 min −1 just below the ice to 0.2 pM O 2 min −1 at 2000 m. These rates are low compared to most other ocean regions, but they could decrease particulate organic carbon and nitrogen by 76% and 74%, respectively, over a period of ∼6 months. The R O 2 calculations based on measurements made at 0 °C yielded a power function of R O 2 vs. depth ( Z) of R O 2 =67 Z −0.5534. When this R O 2 profile was superimposed on a more recent oxygen utilization rate profile made using the 3He– 3H–AOU method (OUR), in the same vicinity of the Nansen Basin during 1987 (OUR=52 Z –0.4058, [Zheng, Y., Schlosser, P., Swift, J.W., Jones, E.P., 1997. Oxygen utilization rates in the Nansen Basin, Arctic Ocean: implications for new production. Deep Sea Research I 44, 1923–1943]), the agreement of the two profiles was close. On one hand, this was to be expected because R O 2 is the biological basis of OUR, on the other hand, it was a surprise because the methodologies are so different. Nitrate mineralization obtained from ETS activities also compared favorably with calculations based on the data of Zheng et al. [1997. Oxygen utilization rates in the Nansen Basin, Arctic Ocean: implications for new production. Deep Sea Research I 44, 1923–1943]. Chlorophyll ranged from 6 ng L −1 at 5 m to 0.06 ng L −1 at 2000 m. Particulate organic carbon (POC) decreased from 0.93 μM C just below the ice to less than 0.4 μM C at 500 m. Particulate organic nitrogen (PON) was not detectable below 70 m, however in the upper 70 m it ranged from 0.16 to 0.04 μM N. The C/N mass ratio over these depths ranged from 5.8 to 11.3. Annual carbon productivity as calculated to balance the total water column respiration was 27 g C m −2 y −1. The integrated respiration rate between 50 and 4000 m suggests that exported production and carbon flux from the 50 m level was 24 g C m −2 y −1. These are minimal estimates for the southern Nansen Basin because they are based on measurements made at the end of the Arctic winter.

Heavy metals in zooplankton and decapod crustaceans from the Barents Sea

Trace metals (Cd, Cu, Pb and Zn) were analysed in zooplankton samples and decapod crustaceans collected on cruises of “RV Walther Herwig III” to the Barents Sea (Summer 1991, 1994 and 2000). We found a substantial spatial heterogeneity in the decapod crustacean Pandalus borealis, with increasing Cd concentrations from the south (North Cape Bank; 0.7 mg kg − 1 DW) to the north (north of Svalbard; 4.7 mg kg − 1 ), supporting the hypothesis that the frequently reported Cd-anomaly in polar crustaceans might be extended to the Barents Sea. Regarding various crustaceans and zooplankton collectives (2000) a distinct interspecific heterogeneity of metals was obvious, with lowest Cd concentrations in euphausiids and chaetognaths and highest ones in decapods and hyperiid amphipods; lowest Cu concentrations in chaetognaths and copepods and highest ones in euphausiids and decapods; and lowest Zn concentrations in euphausiids and decapods and highest ones in some copepods. For Pb many values were below or close to the limit of detection, suggesting that Pb concentrations about 0.4 mg kg − 1 might serve as a regional background value. Results for Cd, Cu and Zn in copepods of this study are largely within the reported range, but high Cd concentrations in copepods from summer in contrast to reported lower ones during winter/spring may be related either to changing accumulation strategies of the copepod species involved or to seasonally changing Cd absorption in copepods from food.

Black feathers in Svalbard: the Alpini expeditions, 1928

This paper lists all the Italian expeditions in search of the airship Italia, commanded by General Umberto Nobile, which crashed to the north of Svalbard on 25 May 1928. There were several such expeditions that involved members of the Alpini, the elite mountain corps of the Italian army. The Italian government had allowed Nobile the services of nine Alpini under the command of Captain Gennaro Sora. The original intention had been that they should assist at the base and, in emergency, should act as a rescue team. This they proceeded to do after it had become clear that the airship had disappeared. The Alpini completed much travelling around Svalbard and while unsuccessful in the main object of their search, accomplished some exploration, including the discovery of an island that was named Alpiniøya by Sora.

Glacial–interglacial cycles in Sr and Nd isotopic composition of Arctic marine sediments triggered by the Svalbard/Barents Sea ice sheet

Sr and Nd isotopic compositions of Arctic marine sediments characterize changes of sediment source regions and trace shelf–ocean particle pathways during glacial–interglacial transitions in the eastern Arctic Ocean. In the 140-ka sedimentary record of a marine core from Yermak Plateau, north of Svalbard, 87Sr/ 86Sr ratios and ε Nd values vary between 0.717 and 0.740 and −9.3 and −14.9, respectively. Sr and Nd isotopic composition both change characteristically during glacial–interglacial cycles and are correlated with the extension of the Svalbard/Barents Sea ice sheet (SBIS). The downcore variation in Sr and Nd isotopic composition indicates climatically induced changes in sediment provenance from two isotopically distinct end-members: (1) Eurasian shelf sediments as a distal source; and (2) Svalbard bedrock as a proximal source that coincide with a change in transport mechanism from sea ice to glacial ice. During glacier advance from Svalbard and intensified glacial bedrock erosion, ε Nd values decrease gradually to a minimum value of −14.9 due to increased input of crystalline Svalbard bedrock material. During glacial maxima, the SBIS covered the entire Barents Sea shelf and supplied increasing amounts of Eurasian shelf material to the Arctic Ocean as ice rafted detritus (IRD). ε Nd values in glacial sediments reach maximum values that are comparable to the average value of modern Eurasian shelf and sea ice sediments ( ε Nd=−10.3). This confirms ice rafting as a major sediment transport mechanism for Eurasian shelf sediments into the Arctic Ocean and trace a sediment origin from the Kara Sea/Laptev Sea shelf area. After the decay of the shelf-based SBIS, the glacial shelf sediment spikes during glacial terminations I ( ε Nd=−10.6) and II ( ε Nd=−10.1) ε Nd values rapidly decrease to values of −12.5 typical for interglacial averages. The downcore Sr isotopic composition is anticorrelated to the Nd isotopic composition, but may be also influenced by grain-size effects. In contrast, the Nd isotopic composition in clay- to silt-size fractions of one bulk sediment sample is similar to within 0.3–0.8 ε Nd units and seems to be a grain-size independent provenance tracer.

Snow Distribution at a High Arctic Site at Svalbard

In the Arctic regions snow cover has a major influence on the environment both in a hydrological and ecological context. Due to strong winds and open terrain the snow is heavily redistributed and the snow depth is quite variable. This has a significant influence on the duration of the melting season, on the possibilities of greenhouse gas exchange, the plant growing season and therefore the arctic terrestrial fauna. The aim of this study is to describe the snow depth variability by detailed measurement of snow distribution in a 3 km2 site near to Ny-Ålesund at 79° north of Svalbard and to link this to topography and climate at the location. The measurements were carried out in a grid of 100 m by 100 m cells using the SIR-2 Georadar from Geophysical Survey System Inc. (GSSI). Differential GPS was used to create a detailed Digital Elevation Model (DEM) and the snow depth data were correlated to topographic data. The average snowdepth in the area was about 70 cm with a standard deviation of 40 cm. Statistical distribution and spatial correlation for the snow depths were found. The method was found acceptable for snow distribution mapping. The main observation was the major accumulation in the west facing slopes due to easterly winds that are dominant in this area.

Spatial variability of phytoplankton, nutrients and new production estimates in the waters around Svalbard

Phytoplankton dynamics and carbon input into Arctic and sub-Arctic ecosystems were investigated around Svalbard, in summer 1991. Phytoplankton biomass, species composition and dissolved nutrient concentrations were analysed from water samples collected along seven transects. Phytoplankton biomass was low especially to the north (Chlorophyll-a mean 0.3 pg 1- '), where flagellates dominated the communities and only ice-diatoms were present. To the west, the phytoplankton composition was representative of a summer Atlantic community, in a post-bloom state. Zooplankton grazing, mainly by copepods, appeared to be the main control on biomass to the west and north of Svalbard. In the Barents Sea (east of Svalbard), an ice edge bloom was observed (Chlorophyll-a max. 6.8 pgl-') and the ice edge receded at a rate of approximately 1 1 km day-'. The phytoplankton community was represented by marginal ice species, especially Phaeocystis poucherii and Chaeroceros socialis. South of the ice edge, Deep Chlorophyll Maxima (DCM) were observed, as surface waters became progressively nutrient-depleted. In these surface waters, the phytoplankton were predominantly auto- and heterotrophic flagellates. Carbon production measurements revealed high net production (new and regenerated) to the north of the Barents Sea Polar Front (BSFW); it was especially high at the receding ice edge (reaching 1.44gC m-'day-'). To the south, a low level of production was maintained, mainly through regenerative processes.

Spatial variability of phytoplankton, nutrients and new production estimates in the waters around Svalbard

Phytoplankton dynamics and carbon input into Arctic and sub-Arctic ecosystems were investigated around Svalbard, in summer 1991. Phytoplankton biomass, species composition and dissolved nutrient concentrations were analysed from water samples collected along seven transects. Phytoplankton biomass was low especially to the north (Chlorophyll-a mean 0.3 pg 1- '), where flagellates dominated the communities and only ice-diatoms were present. To the west, the phytoplankton composition was representative of a summer Atlantic community, in a post-bloom state. Zooplankton grazing, mainly by copepods, appeared to be the main control on biomass to the west and north of Svalbard. In the Barents Sea (east of Svalbard), an ice edge bloom was observed (Chlorophyll-a max. 6.8 pgl-') and the ice edge receded at a rate of approximately 1 1 km day-'. The phytoplankton community was represented by marginal ice species, especially Phaeocystis poucherii and Chaeroceros socialis. South of the ice edge, Deep Chlorophyll Maxima (DCM) were observed, as surface waters became progressively nutrient-depleted. In these surface waters, the phytoplankton were predominantly auto- and heterotrophic flagellates. Carbon production measurements revealed high net production (new and regenerated) to the north of the Barents Sea Polar Front (BSFW); it was especially high at the receding ice edge (reaching 1.44gC m-'day-'). To the south, a low level of production was maintained, mainly through regenerative processes.

Reproduction and larval ecology of the Arctic fish speciesArtediellus atlanticus (Cottidae)

State of maturity, egg numbers, as well as gonadosomatic index (GSI), and relative fecundity were determined in 209 females of the cottid speciesArtediellus atlanticus. Specimens were caught by Agassiz and bottom trawls during two expeditions of RV “Polarstern” to the shelf off northeast Greenland (ARK VII/2; July/August 1990) as well as to the Barents Sea and the shelf areas surrounding Svalbard (ARK VIII/2 — Arctic EPOS; June/July 1991). Analysis of the state of maturity showed thatA. atlanticus spawns from late summer to autumn. Individuals from northern populations spawn later (November) than those from more southern locations (July to September). The total number of eggs (40–216) was small due to their large diameter and the small size of the fish. The mean GSI of females from the central Barents Sea (36.9±6.5%;n=24) was significantly higher (P<0.001) than the GSI of females caught off eastern Svalbard (18.7±4.0%;n=14), compared at stage IV of maturity. The mean relative fecundity was significantly higher (P<0.001) for females of the central Barents Sea (17.9±2.3;n=19) than for females caught on more northern stations east of Svalbard (6.9±1.8;n=17) and north of Svalbard (6.4±0.5;n=7). Individuals ofA. atlanticus that were maintained at 0°C spawned in the aquaria, allowing observation of the development of their eggs and larvae for 1 year. The eggs needed more than 200 days to develop. The larvae hatched at a very advanced stage and were similar to the adults in appearance and behaviour. The larvae grew at a rate of 0.02 mm per day and showed a benthic mode of life.

The potential transport of pollutants by Arctic sea ice

Drifting sea ice in the Arctic may transport contaminants from coastal areas across the pole and release them during melting far from the source areas. Arctic sea ice often contains sediments entrained on the Siberian shelves and receives atmospheric deposition from Arctic haze. Elevated levels of some heavy metals (e.g. lead, iron, copper and cadmium) and organochlorines (e.g. PCBs and DDTs) have been observed in ice sampled in the Siberian seas, north of Svalbard, and in Baffin Bay. In order to determine the relative importance of sea ice transport in comparison with air/sea and oceanic processes, more data is required on pollutant entrainment and distribution in the Arctic ice pack.

Ambient noise characteristics of the northwestern Barents Sea

In support of the 1988–1989 CEAREX drift experiment three ANMET ambient noise buoys were inserted on ice floes in a triangular pattern approximately 120 km on a side about 200 km north of Svalbard in mid-September 1988. The buoys drifted southward passing to the east of Svalbard providing hourly measurements of the noise field from 5–4000 Hz for 2–4 months. Extensive environmental data were available with which to examine the effect of wind stress and ice motion on the noise field. The median spectra from these three buoys were quite similar with differences of about 3 dB being observed, the larger differences being at the higher frequencies where local noise effects dominate. The spectra were comparable to those found in the Eurasian Basin in winter. A 12-h periodicity was noted in both the noise and ice speed data, the result of forcing by tidal or inertial oscillations. A 52-h periodicity was noted at one buoy which lasted through the winter and was subjected to recurring synoptic scale storms. For frequencies below 100 Hz the temporal coherency was about 15 h. At low frequencies wind stress was the most important noise correlate, followed closely by ice speed. The noise field responded rapidly to the passage of storms generated by the Icelandic Low which migrated over the northern Barents Sea with the arrival of the noise peak being associated with the time of passage of the storm front past each buoy.