ALBERT

Description: The NEG2017 cruise took place from 23 August 2017 to 11 September 2017 was part of the Strategic Environmental program for Northeast Greenland with as its goal to provide environmental impact information pertaining to potential oil exploitation and oil spill response activities in the region. The cruise leader for NEG2017 was Eva Friis Møller.

Description: Time series of currents, salinity (conductivity), temperature Chlorophyl-a and CDOM were obtained in the period May- June 2014 by use of a McLane ice-tethered profiler in Young Sound, Greenland. At YS05 (74.238 N, 20.188 W) the mooring consisted of a 600 kHz downward-looking Nortek Aquadopp ADCP and an SBE 52-MP CTD (accuracy temperature ±0.002 C and conductivity ±0.0003 Sm-1) and WetLab ECO triplet (Cholorphyll-a and CDOM). Velocities were corrected for magnetic deviation (18.5o). The water column sampling spanned between 1.5 and 30 m depth every 30 min. The ADCP was set to sample 80 bins (bin size of 0.5 m) and each bin consisted of a 1 min ensemble average of 60 pings. The first and last bins were centred at 1m and 41 m depth. Only bins between 2.5 and 30 m were adequately measured. For further details see Boone et al., 2017 (Circulation and fjord-shelf exchange during the ice-covered period in Young Sound-Tyrolerfjord, Northwest Greenland (74 N). Estuar. Coast. Shelf Sci., 15, 194-205. https://doi.org/10.1016/j.ecss.2017.06.021).

Description: CTD data was obtained in the period April-June 2014 in Young Sound, Greenland. CTD casts were performed using an SBE-19 plus CTD (accuracy: ±0.005 C and ±0.0005 Sm-1) which was lowered through ice-drilled holes. In total, 4 transects were performed and covered from the mouth to the head of the fjord. Standardized routines of Seabird software were used on the data set for quality control and bin averaging. The data sets consist of profiles of practical salinity, temperature, potential temperature, dissolved oxygen, fluorescence, turbidity, and irradiance (PAR). For further details see Boone et al., 2017 (Circulation and fjord-shelf exchange during the ice-covered period in Young Sound-Tyrolerfjord, Northwest Greenland (74o N). Estuar. Coast. Shelf Sci., 15, 194-205. https://doi.org/10.1016/j.ecss.2017.06.021).

Description: Time series of currents were obtained in the period May- June 2014 by use of an ice-tethered mooring in Young Sound, Greenland. At YS07 (74.233o N, 20.133o W) the mooring consisted of a 600 kHz downward-looking Nortek Aquadopp ADCP. Velocities were corrected for magnetic deviation (18.5o). The water column sampling spanned between 1.5 and 30 m depth every 30 min. The ADCP was set to sample 80 bins (bin size of 0.5 m) and each bin consisted of a 1 min ensamble average of 60 pings. The first and last bins were centred at 1m and 41 m depth. Only bins between 2.5 and 30 m were adequately measured. For further details see Boone et al., 2017 (Circulation and fjord-shelf exchange during the ice-covered period in Young Sound-Tyrolerfjord, Northwest Greenland (74o N). Estuar. Coast. Shelf Sci., 15, 194-205. https://doi.org/10.1016/j.ecss.2017.06.021).

Description: This is the first high temporal-resolution study in Disko Bay covering population dynamics, grazing, reproduction, and biochemical composition of 3 dominating copepod species (Calanus finmarchicus, C. glacialis and C. hyperboreus) from late winter to midsummer in 2008. C. finmarchicus and C. glacialis ascended to the surface layer at the onset of the spring phytoplankton bloom, followed by C. hyperboreus 2 wk later. C. finmarchicus spawning occurred during the bloom and postbloom period, partially fueled by wax esters. C. glacialis commenced spawning before the bloom, yet it was greatly stimulated when food became available. However, feeding and reproduction was terminated after the main bloom despite the presence of food. In terms of feeding, this was also the strategy for C. hyperboreus. Between pre-bloom and post-bloom, C. finmarchicus showed an increase in carbon, nitrogen, and phospholipid content but a decrease in total lipid content. This was likely the result of protein synthesis, oocyte maturation, and spawning fueled by wax esters and by feeding. C. glacialis showed a similar pattern, although with an increasing total lipid content from pre-bloom to post-bloom, and an increasing wax ester and decreasing phospholipid content after reproduction was terminated. C. hyperboreus showed greatly increased content of carbon, nitrogen, and all lipid classes between the pre- and post-bloom periods. Hence, C. finmarchicus commenced feeding and spawning at the onset of the bloom and continued throughout the remaining study period. Both C. glacialis and C. hyperboreus females refueled their storage lipids (wax esters) during the bloom and post-bloom period, suggesting that they may spawn in an additional year.

Description: This study describes differences in plankton community structure and in chemical and physical gradients between the offshore West Greenland Current system and inland regions close to the Greenland Ice Sheet during the post-bloom in Godthabsfjorden (64° N, 51° W). The offshore region had pronounced vertical mixing, with centric diatoms and Phaeocystis spp. dominating the phytoplankton, chlorophyll (chl) a (0.3 to 3.9 µg/l) was evenly distributed and nutrients were depleted in the upper 50 m. Ciliates and heterotrophic dinoflagellates constituted equal parts of the protozooplankton biomass. Copepod biomass was dominated by Calanus spp. Primary production, copepod production and the vertical flux were high offshore. The water column was stratified in the fjord, causing chl a to be concentrated in a thin sub-surface layer. Nutrients were depleted above the pycnocline, and Thalassiosira spp. dominated the phytoplankton assemblage close to the ice sheet. Dinoflagellates dominated the protozooplankton biomass, whereas copepod biomass was low and was dominated by Pseudocalanus spp. and Metridia longa. Primary production was low in the outer part of the fjord but considerably higher in the inner parts of the fjord. Copepod production was exceeded by protozooplankton production in the fjord. The results of both physical/chemical factors and biological parameters suggest separation of offshore and fjord systems.

Description: Photogrammetric reanalysis of 1985 aerial photos has revealed substantial submarine melting of the floating ice tongue of Jakobshavn Isbrae, west Greenland. The thickness of the floating tongue determined from hydrostatic equilibrium tapers from ~940 m near the grounding zone to ~600 m near the terminus. Feature tracking on orthophotos shows speeds on the July 1985 ice tongue to be nearly constant (~18.5 m/d), indicating negligible dynamic thinning. The thinning of the ice tongue is mostly due to submarine melting with average rates of 228 ± 49 m/yr (0.62 ± 0.13 m/d) between the summers of 1984 and 1985. The cause of the high melt rate is the circulation of warm seawater (thermal forcing of up to 4.2°C) beneath the tongue with convection driven by the substantial discharge of subglacial freshwater from the grounding zone. We believe that this buoyancy-driven convection is responsible for a deep channel incised into the sole of the floating tongue. A dramatic thinning, retreat, and speedup began in 1998 and continues today. The timing of the change is coincident with a 1.1°C warming of deep ocean waters entering the fjord after 1997. Assuming a linear relationship between thermal forcing and submarine melt rate, average melt rates should have increased by ~25% (~57 m/yr), sufficient to destabilize the ice tongue and initiate the ice thinning and the retreat that followed.

Description: Time series of currents were obtained in the period May- June 2014 by use of an ice-tethered mooring in Young Sound, Greenland. At YS06 (74.245o N, 20.229o W) the mooring consisted of a 600 kHz downward-looking Nortek Aquadopp ADCP. Velocities were corrected for magnetic deviation (18.5o). The water column sampling spanned between 1.5 and 30 m depth every 30 min. The ADCP was set to sample 80 bins (bin size of 0.5 m) and each bin consisted of a 1 min ensamble average of 60 pings. The first and last bins were centred at 1m and 41 m depth. Only bins between 2.5 and 30 m were adequately measured. For further details see Boone et al., 2017 (Circulation and fjord-shelf exchange during the ice-covered period in Young Sound-Tyrolerfjord, Northwest Greenland (74o N). Estuar. Coast. Shelf Sci., 15, 194-205. https://doi.org/10.1016/j.ecss.2017.06.021).

Description: Time series of currents were obtained in the period October 2013 and May 2014 by use of an ice-tethered mooring in Young Sound, Greenland. At YS02 (74.267o N, 20.248o W) the mooring consisted of a 300 kHz downward-looking Teledyne RDI Workhorse Sentinel acoustic Doppler current profiler (ADCP) measuring horizontal and vertical current velocities. Velocity precision and resolution were ±1% and ±5 cm s-1, respectively, while compass accuracy and resolution were ±2 and 0.1 degrees. The ADCP was set to sample 39 bins (bin size of 2m), where each 10 min sample consists of averages of 20 pings. The first and last bins were set at 6 and 84 m depth. Velocities were corrected for magnetic deviation (18.5 degrees) and samples with insufficient acoustic backscatter in the water column were eliminated with the RDI ADCP software. For further details see Boone et al., 2017 (Circulation and fjord-shelf exchange during the ice-covered period in Young Sound-Tyrolerfjord, Northwest Greenland (74o N). Estuar. Coast. Shelf Sci., 15, 194-205. https://doi.org/10.1016/j.ecss.2017.06.021).