ALBERT

Description: Despite the importance of surface energy budgets (SEBs) for land-climate interactions in the Arctic, uncertainties in their prediction persist. In situ observational data of SEB components - useful for research and model validation - are collected at relatively few sites across the terrestrial Arctic, and not all available datasets are readily interoperable. Furthermore, the terrestrial Arctic consists of a diversity of vegetation types, which are generally not well represented in land surface schemes of current Earth system models. This dataset describes the data generated in a literature synthesis, covering 358 study sites on vegetation or glacier (〉=60°N latitude), which contained surface energy budget observations. The literature synthesis comprised 148 publications searched on the ISI Web of Science Core Collection.

Description: The rewetting of peatlands is a promising measure to mitigate greenhouse gas (GHG) emissions by preventing the further mineralization of the peat soil through aeration. In coastal peatland, the rewetting with brackish water can increase the GHG mitigation potential by the introduction of sulfate, a terminal electron acceptor (TEA). Sulfate is known to lower the CH4 production and thus, its emission by favoring the growth of sulfate-reducers, which outcompete methanogens for substrate. The data contain porewater variables such as pH, electrical conductivity (EC) and sulfate, chloride, dissolved CO2 and CH4 concentrations, as well as absolute abundances of methane- and sulfate-cycling microbial communities. The data were collected in spring and autumn 2019 after a storm surge with brackish water inflow in January 2019. Field sampling was conducted in the nature reserve Heiligensee and Hütelmoor in North-East Germany, close to the Southern Baltic Sea coast. We took peat cores using a Russian peat corer in addition to pore water diffusion samplers and plastic liners (length: 60cm; inner diameter 10 cm) at four locations along a transect from further inland towards the Baltic Sea. We wanted to compare the soil and pore water geochemistry as well as the microbial communities after the brackish water inflow to the common freshwater rewetting state. Pore water was extracted using pore water suction samplers in the lab and environmental variables were quantified with an ICP. Microbial samples were sampled from the peat core using sterile equipment. We used quantitative polymerase chain reaction (qPCR) to characterize pools of DNA and cDNA targeting total and putatively active bacteria and archaea. qPCR was performed on key functional genes of methane production (mcrA), aerobic methane oxidation (pmoA) and sulfate reduction (dsrB) in addition to the 16S rRNA gene for the absolute abundance of total prokaryotes. Furthermore, we retrieved soil plugs to determine the concentrations and isotopic signatures of dissolved trace gases (CO2/DIC and CH4) in the pore water.

Description: This dataset provides annually resolved microfacies data from ICDP core 5017-1-A, retrieved from the deep northern Dead Sea basin in 2010/11, for the last glacial-interglacial transition (ca. 14-13 ka BP). Sediments of the Lisan Formation were investigated between ~94.7 and 91.8 m sediment depth below lake floor (lithozone C2) by continuous thin section microscopy. Thin sections were prepared following the standard procedure by Brauer and Casanova (2001) that was adjusted for salty sediments. Thin section analyses were performed on overlapping large-scale thin sections using a Zeiss Axiolab pol microscope at magnifications of 50-400x. Microfacies analyses included varve counting and measurements of varve and sublayer thickness. The amount of varves in erosional gaps was interpolated and the position of mass flow deposits (MFD) is marked.

Description: We present sea ice temperature and salinity data from first-year ice (FYI) and second-year ice (SYI) relevant to the temporal development of sea ice permeability and brine drainage efficiency from the early growth phase in October 2019 to the onset of spring warming in May 2020. Our dataset was collected in the central Arctic Ocean during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) Expedition in 2019 to 2020. MOSAiC was an international transpolar drift expedition in which the German icebreaker RV Polarstern anchored into an ice floe to gain new insights into Arctic climate over a full annual cycle. In October 2019, RV Polarstern moored to an ice floe in the Siberian sector of the Arctic at 85 degrees north and 137 degrees east to begin the drift towards the North Pole and the Fram Strait via the Transpolar Drift Stream. The data presented here were collected during the first three legs of the expedition, so all the coring activities took place on the same floe. The end dates of legs 1, 2, and 3 were 13 December, 24 February, and 4 June, respectively. The dataset contributed to a baseline study entitled, Deciphering the properties of different Arctic ice types during the growth phase of the MOSAiC floes: Implications for future studies. The study highlights downward directed gas pathways in FYI and SYI by inferring sea ice permeability and potential brine release from several time series of temperature and salinity measurements. The physical properties presented in this paper lay the foundation for subsequent analyses on actual gas contents measured in the ice cores, as well as air-ice and ice-ocean gas fluxes. Sea ice cores were collected with a Kovacs Mark II 9 cm diameter corer. To measure ice temperatures, about 4.5 cm deep holes were drilled into the core (intervals varied by site and leg) . The temperatures were measured by a digital thermometer within minutes after the cores were retrieved. The ice cores were placed into pre-labelled plastic sleeves sealed at the bottom end. The ice cores were transported to RV Polarstern and stored in a -20 degrees Celsius freezer. Each of the cores was sub-sampled, melted at room temperature, and processed for salinity within one or two days. The practical salinity was estimated by measuring the electrical conductivity and temperature of the melted samples using a WTW Cond 3151 salinometer equipped with a Tetra-Con 325 four-electrode conductivity cell. The practical salinity represents the the salinity estimated from the electrical conductivity of the solution. The dataset also contains derived variables, including sea ice density, brine volume fraction, and the Rayleigh number.

Description: Organic carbon (OC) stored in Arctic permafrost represents one of Earth’s largest and most vulnerable terrestrial carbon pools. Amplified climate warming across the Arctic results in widespread permafrost thaw. Permafrost deposits exposed at river cliffs and coasts are particularly susceptible to thawing processes. Accelerating erosion of terrestrial permafrost along shorelines leads to increased transfer of organic matter (OM) to nearshore waters. However, the amount of terrestrial permafrost carbon and nitrogen as well as the OM quality in these deposits are still poorly quantified. Here, we characterise the sources and the quality of OM supplied to the Lena River at a rapidly eroding permafrost river shoreline cliff in the eastern part of the delta (Sobo-Sise Island). Our multi-proxy approach captures bulk elemental, molecular geochemical and carbon isotopic analyses of late Pleistocene Yedoma permafrost and Holocene cover deposits, discontinuously spanning the last ~52 ka. We show that the ancient permafrost exposed in the Sobo-Sise cliff has a high organic carbon content (mean of about 5 wt%).We found that the OM quality, which we define as the intrinsic potential to further transformation, decomposition, and mineralization, is also high as inferred by the lipid biomarker inventory. The oldest sediments stem from Marine Isotope Stage (MIS) 3 interstadial deposits (dated to 52 to 28 cal kyr BP) and is overlaid by Last Glacial MIS 2 (dated to 28 to 15 cal ka BP) and Holocene MIS 1 (dated to 7–0 cal ka BP) deposits. The relatively high average chain length (ACL) index of n-alkanes along the cliff profile indicates a predominant contribution of vascular plants to the OM composition. The elevated ratio of iso and anteiso-branched FAs relative to long chain (C ≥ 20) n-FAs in the interstadial MIS 3 and the interglacial MIS 1 deposits, suggests stronger microbial activity and consequently higher input of bacterial biomass during these climatically warmer periods. The overall high carbon preference index (CPI) and higher plant fatty acid (HPFA) values as well as high C / N ratios point to a good quality of the preserved OM and thus to a high potential of the OM for decomposition upon thaw. A decrease of HPFA values downwards along the profile probably indicates a relatively stronger OM decomposition in the oldest (MIS 3) deposits of the cliff.

Description: We present sea ice temperature and salinity data from first-year ice (FYI) and second-year ice (SYI) relevant to the temporal development of sea ice permeability and brine drainage efficiency from the early growth phase in October 2019 to the onset of spring warming in May 2020. Our dataset was collected in the central Arctic Ocean during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) Expedition in 2019 to 2020. MOSAiC was an international transpolar drift expedition in which the German icebreaker RV Polarstern anchored into an ice floe to gain new insights into Arctic climate over a full annual cycle. In October 2019, RV Polarstern moored to an ice floe in the Siberian sector of the Arctic at 85 degrees north and 137 degrees east to begin the drift towards the North Pole and the Fram Strait via the Transpolar Drift Stream. The data presented here were collected during the first three legs of the expedition, so all the coring activities took place on the same floe. The end dates of legs 1, 2, and 3 were 13 December, 24 February, and 4 June, respectively. The dataset contributed to a baseline study entitled, Deciphering the properties of different Arctic ice types during the growth phase of the MOSAiC floes: Implications for future studies. The study highlights downward directed gas pathways in FYI and SYI by inferring sea ice permeability and potential brine release from several time series of temperature and salinity measurements. The physical properties presented in this paper lay the foundation for subsequent analyses on actual gas contents measured in the ice cores, as well as air-ice and ice-ocean gas fluxes. Sea ice cores were collected with a Kovacs Mark II 9 cm diameter corer. To measure ice temperatures, about 4.5 cm deep holes were drilled into the core (intervals varied by site and leg) . The temperatures were measured by a digital thermometer within minutes after the cores were retrieved. The ice cores were placed into pre-labelled plastic sleeves sealed at the bottom end. The ice cores were transported to RV Polarstern and stored in a -20 degrees Celsius freezer. Each of the cores was sub-sampled, melted at room temperature, and processed for salinity within one or two days. The practical salinity was estimated by measuring the electrical conductivity and temperature of the melted samples using a WTW Cond 3151 salinometer equipped with a Tetra-Con 325 four-electrode conductivity cell. The practical salinity represents the the salinity estimated from the electrical conductivity of the solution. The dataset also contains derived variables, including sea ice density, brine volume fraction, and the Rayleigh number.

Description: These datasets describe sediment samples taken from the Batagay megaslump, located in Yana Uplands in northeastern Siberia. Most sediment samples were taken from the slump headwall (B19-P1) by rapelling down on a rope from the slump surface and taking samples with a hole saw (diameter 55 mm, 40 mm deep) mounted on a handheld power drill. A second profile (B19-02) of the lowest part of the slump headwall was sampled (~100 m south) using a hammer and axe from the slump floor. Two permafrost sediment blocks (B19-03 and B19-04) at the slump bottom that had fallen from the headwall were sampled using a chainsaw. Finally, a baidzherakh (thermokarst mound; B19-05) in the north of the slump was sampled using a hammer and axe. The samples cover 5 stratigraphical units: 1. lower ice complex, 2. lower sand unit, 3. woody layer, 4. upper ice complex, 5. Holocene cover.

Description: Organic carbon (OC) stored in Arctic permafrost represents one of Earth’s largest and most vulnerable terrestrial carbon pools. Amplified climate warming across the Arctic results in widespread permafrost thaw. Permafrost deposits exposed at river cliffs and coasts are particularly susceptible to thawing processes. Accelerating erosion of terrestrial permafrost along shorelines leads to increased transfer of organic matter (OM) to nearshore waters. However, the amount of terrestrial permafrost carbon and nitrogen as well as the OM quality in these deposits are still poorly quantified. Here, we characterise the sources and the quality of OM supplied to the Lena River at a rapidly eroding permafrost river shoreline cliff in the eastern part of the delta (Sobo-Sise Island). Our multi-proxy approach captures bulk elemental, molecular geochemical and carbon isotopic analyses of late Pleistocene Yedoma permafrost and Holocene cover deposits, discontinuously spanning the last ~52 ka. We show that the ancient permafrost exposed in the Sobo-Sise cliff has a high organic carbon content (mean of about 5 wt%).We found that the OM quality, which we define as the intrinsic potential to further transformation, decomposition, and mineralization, is also high as inferred by the lipid biomarker inventory. The oldest sediments stem from Marine Isotope Stage (MIS) 3 interstadial deposits (dated to 52 to 28 cal kyr BP) and is overlaid by Last Glacial MIS 2 (dated to 28 to 15 cal ka BP) and Holocene MIS 1 (dated to 7–0 cal ka BP) deposits. The relatively high average chain length (ACL) index of n-alkanes along the cliff profile indicates a predominant contribution of vascular plants to the OM composition. The elevated ratio of iso and anteiso-branched FAs relative to long chain (C ≥ 20) n-FAs in the interstadial MIS 3 and the interglacial MIS 1 deposits, suggests stronger microbial activity and consequently higher input of bacterial biomass during these climatically warmer periods. The overall high carbon preference index (CPI) and higher plant fatty acid (HPFA) values as well as high C / N ratios point to a good quality of the preserved OM and thus to a high potential of the OM for decomposition upon thaw. A decrease of HPFA values downwards along the profile probably indicates a relatively stronger OM decomposition in the oldest (MIS 3) deposits of the cliff.

Description: We present sea ice temperature and salinity data from first-year ice (FYI) and second-year ice (SYI) relevant to the temporal development of sea ice permeability and brine drainage efficiency from the early growth phase in October 2019 to the onset of spring warming in May 2020. Our dataset was collected in the central Arctic Ocean during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) Expedition in 2019 to 2020. MOSAiC was an international transpolar drift expedition in which the German icebreaker RV Polarstern anchored into an ice floe to gain new insights into Arctic climate over a full annual cycle. In October 2019, RV Polarstern moored to an ice floe in the Siberian sector of the Arctic at 85 degrees north and 137 degrees east to begin the drift towards the North Pole and the Fram Strait via the Transpolar Drift Stream. The data presented here were collected during the first three legs of the expedition, so all the coring activities took place on the same floe. The end dates of legs 1, 2, and 3 were 13 December, 24 February, and 4 June, respectively. The dataset contributed to a baseline study entitled, Deciphering the properties of different Arctic ice types during the growth phase of the MOSAiC floes: Implications for future studies. The study highlights downward directed gas pathways in FYI and SYI by inferring sea ice permeability and potential brine release from several time series of temperature and salinity measurements. The physical properties presented in this paper lay the foundation for subsequent analyses on actual gas contents measured in the ice cores, as well as air-ice and ice-ocean gas fluxes. Sea ice cores were collected with a Kovacs Mark II 9 cm diameter corer. To measure ice temperatures, about 4.5 cm deep holes were drilled into the core (intervals varied by site and leg) . The temperatures were measured by a digital thermometer within minutes after the cores were retrieved. The ice cores were placed into pre-labelled plastic sleeves sealed at the bottom end. The ice cores were transported to RV Polarstern and stored in a -20 degrees Celsius freezer. Each of the cores was sub-sampled, melted at room temperature, and processed for salinity within one or two days. The practical salinity was estimated by measuring the electrical conductivity and temperature of the melted samples using a WTW Cond 3151 salinometer equipped with a Tetra-Con 325 four-electrode conductivity cell. The practical salinity represents the the salinity estimated from the electrical conductivity of the solution. The dataset also contains derived variables, including sea ice density, brine volume fraction, and the Rayleigh number.

Description: Rock magnetic and paleomagnetic results covering the past 30 ka were constructed from two sediment cores MSM33_856-1 (MSM33-55-1) and MSM33_855-1 (54-3) from the Black Sea. After the Mediterranean Sea water ingression, finely laminated organic-rich sapropelic sediments and coccolith oozes were deposited in the Black Sea since about 8.3 ka. Relict magnetic minerals in the Black Sea sarpoples are ferrous hemoilmenite, Fe-Mn and Fe-Cr spinels, and magnetite inclusions. In sediments deposited between about 14 and 8 ka, greigite and pyrite were formed in sediments because of the seawater penetration from overlying sediments after the seawater ingression. Before ~14 ka, the Black Sea sediments are dominated by detrital (titano-)magnetite minerals and the sporadically formed greigite which has SIRM/kLF ratios 〉 10 kAm-2. By comparison with detrital (titano-)magnetite samples between 20-30 ka, we found that relict magnetic mineral samples between 0-8.3 ka have similar behavior in recording the geomagnetic field. Moreover, the geomagnetic field variations reconstructed from the Black Sea sapropels are comparable with other validated regional datasets for the past 8.3 ka. The natural remanent magnetization (NRM) and the anhysteretic remanent magnetization (ARM) were measured with a 2G Enterprises 755 SRM (cryogenic) long-core magnetometer equipped with a sample holder for eight discrete samples at a separation of 20 cm. The magnetometer's in-line tri-axial alternating field (AF) demagnetizer was used to demagnetize the NRM and ARM of the samples. The NRM was measured after application of AF peak amplitudes of 0, 5, 10, 15, 20, 30, 40, 50, 65, 80, and 100 mT. Directions of the characteristic remanent magnetization (ChRM) were determined by principle component analysis (PCA) according to Kirschvink (1980). The error range of the ChRM is given as the maximum angular deviation (MAD). The ARM was imparted along the samples' z-axis with a static field of 0.05 mT and an AF field of 100 mT. Demagnetization then was performed in steps of 0, 10, 20, 30, 40, 50, 65, and 80 mT. The median destructive field of the ARM (MDFARM) was determined to estimate the coercivity of the sediments. The slope of NRM versus ARM of common demagnetization steps was used to determine the relative paleointensity (RPI). In most cases, demagnetization steps from 20 to 65 mT were used to determine the RPI.

Description: This dataset provides data for four third-degree tidal constituents used in the publication of Sulzbach et al (2022). The tidal constituents provided are the 3M1, 3M3, 3N2 and 3L2 for 134 globally distributed stations. The tide information, such as the nodal modulations of these tides, are taken from Table 1 and Table S2 of Ray (2020). These tidal constants are estimated using the GESLA dataset (Woodworth et al 2014) following the approach presented in Piccioni et al (2019). This record is an add-on to the full TICON dataset (https://doi.org/10.1594/PANGAEA.896587), using exactly the same data format and pre-processing. These steps include using tide gauge data that contains at least ten years of continuous data. Further, the dataset is restricted to only contain open ocean tide gauges by limiting it to a mean surrounding depth of tide gauges to be deeper than 500 meters in a 2-degree radius and excluding stations not native to the ocean domain of the employed tidal model TiME. Duplicate and closely neighbouring tide gauges, found within a 0.2-degree radius, are also removed from the dataset. This resulted in the availability of the four tidal constants for 134 tide gauges. The results are stored in one tab-separated text/ASCII file with 13 columns: 1. Latitude of the tide gauge station 2. Longitude of the tide gauge station 3. Constituent name 4. Amplitude (in cm) 5. Phase (in degrees) 6. Standard deviation of the amplitude (in cm) 7. Standard deviation of the phase (in degrees) 8. Percentage of missing observations 9. Total number of observations analyzed 10. Length of the maximum temporal gap found in the time series in days 11. Date of the first observation 12. Date of the last observation 13. Code that corresponds to the original source of the record TICON is a useful and easy-to-handle data set for tide model validation and allows the users to select the records according to the different criteria most suitable for their purposes. The options span from the choice of a geographical region to the use of single constituents or time periods.

Description: These datasets provide sedimentological data partly at annual resolution and an age model for the lateglacial part of (1) the ICDP sediment core 5017-1-A retrieved from the deep northern Dead Sea basin in 2010/11, and (2) for the Masada outcrop located at the southwestern shore of the Dead Sea sampled in 2018. The here investigated two sediment sections cover the last glacial-interglacial transition (ca. 17-11.5 ka BP) in the hydroclimatically sensitive Levant, when the water level of Lake Lisan – the precursor of the Dead Sea – dropped dramatically from its glacial high-stand to the Holocene low levels. Here, we analyze the interval between the last two gypsum units – the Upper Gypsum Unit (UGU) and the Additional Gypsum Unit (AGU) – which were also used to correlate the two sites. In the ICDP core this section is located between ~101 and 88.5 m sediment depth below lake floor and at Masada it encompasses the uppermost ~3.8 m sediments of the Lisan Formation, which form the terminal deposit at this site. Due to the lake level decline, the complete transition into the Holocene is only recorded in the ICDP core, while sedimentation at Masada terminates earlier. The microfacies was investigated by continuous thin section microscopy, while additional macroscopic information is provided from over- and underlying sediment sections. A revised chronology using age modelling in OxCal (Ramsey 2008; Ramsey 2009; Ramsey and Lee 2013) was developed for the ICDP core and a floating varve chronology was constructed at Masada. Using these new microfacies data from marginal (Masada) and deep-water (ICDP core) sediments, the hydroclimatic variability during the final stage of Lake Lisan can be reconstructed, which could provide important insights into the development of human sedentism in the region at this time.

Description: We present sea ice temperature and salinity data from first-year ice (FYI) and second-year ice (SYI) relevant to the temporal development of sea ice permeability and brine drainage efficiency from the early growth phase in October 2019 to the onset of spring warming in May 2020. Our dataset was collected in the central Arctic Ocean during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) Expedition in 2019 to 2020. MOSAiC was an international transpolar drift expedition in which the German icebreaker RV Polarstern anchored into an ice floe to gain new insights into Arctic climate over a full annual cycle. In October 2019, RV Polarstern moored to an ice floe in the Siberian sector of the Arctic at 85 degrees north and 137 degrees east to begin the drift towards the North Pole and the Fram Strait via the Transpolar Drift Stream. The data presented here were collected during the first three legs of the expedition, so all the coring activities took place on the same floe. The end dates of legs 1, 2, and 3 were 13 December, 24 February, and 4 June, respectively. The dataset contributed to a baseline study entitled, Deciphering the properties of different Arctic ice types during the growth phase of the MOSAiC floes: Implications for future studies. The study highlights downward directed gas pathways in FYI and SYI by inferring sea ice permeability and potential brine release from several time series of temperature and salinity measurements. The physical properties presented in this paper lay the foundation for subsequent analyses on actual gas contents measured in the ice cores, as well as air-ice and ice-ocean gas fluxes. Sea ice cores were collected with a Kovacs Mark II 9 cm diameter corer. To measure ice temperatures, about 4.5 cm deep holes were drilled into the core (intervals varied by site and leg) . The temperatures were measured by a digital thermometer within minutes after the cores were retrieved. The ice cores were placed into pre-labelled plastic sleeves sealed at the bottom end. The ice cores were transported to RV Polarstern and stored in a -20 degrees Celsius freezer. Each of the cores was sub-sampled, melted at room temperature, and processed for salinity within one or two days. The practical salinity was estimated by measuring the electrical conductivity and temperature of the melted samples using a WTW Cond 3151 salinometer equipped with a Tetra-Con 325 four-electrode conductivity cell. The practical salinity represents the the salinity estimated from the electrical conductivity of the solution. The dataset also contains derived variables, including sea ice density, brine volume fraction, and the Rayleigh number.

Description: This dataset provides annually resolved microfacies data from ICDP core 5017-1-A, retrieved from the deep northern Dead Sea basin in 2010/11, for the last glacial-interglacial transition (ca. 17-11.5 ka BP). Sediments of the Lisan Formation were investigated between ~101 and 88.5 m sediment depth below lake floor by continuous thin section microscopy, while additional macroscopic information is provided from core catchers, as well as from over- and underlying sediment sections. Thin sections were prepared following the standard procedure by Brauer and Casanova (2001) that was adjusted for salty sediments. Thin section analyses were performed on overlapping large-scale thin sections using a Zeiss Axiolab pol microscope at magnifications of 50-400x. Microfacies analyses included varve counting and measurements of varve and sublayer thickness.

Description: Despite the importance of surface energy budgets (SEBs) for land-climate interactions in the Arctic, uncertainties in their prediction persist. In situ observational data of SEB components - useful for research and model validation - are collected at relatively few sites across the terrestrial Arctic, and not all available datasets are readily interoperable. Furthermore, the terrestrial Arctic consists of a diversity of vegetation types, which are generally not well represented in land surface schemes of current Earth system models. This dataset contains metadata information about surface energy budget components measured at 64 tundra and glacier sites 〉60° N across the Arctic. This information was taken from the open-access repositories FLUXNET, Ameriflux, AON, GC-Net and PROMICE. The contained datasets are associated with the publication vegetation type as an important predictor of the Arctic Summer Land Surface Energy Budget by Oehri et al. 2022, and intended to support research of surface energy budgets and their relationship with environmental conditions, in particular vegetation characteristics across the terrestrial Arctic.

Description: This dataset provides the results from Bayesian age depth modelling in OxCal for ICDP core 5017-1-A, retrieved from the deep northern Dead Sea basin in 2010/11, for the last glacial-interglacial transition between ~101 and 88.5 m sediment depth below lake floor (ca. 17-11.5 ka BP). The model was performed in OxCal v.4.4 using a P_Sequence (1,1,C(-2,2)) (Ramsey 2008; Ramsey 2009; Ramsey and Lee 2013) and includes three tephrochronological ages from Neugebauer et al. (2021) and three radiocarbon ages from Kitagawa et al. (2017).

Description: Despite the importance of surface energy budgets (SEBs) for land-climate interactions in the Arctic, uncertainties in their prediction persist. In situ observational data of SEB components - useful for research and model validation - are collected at relatively few sites across the terrestrial Arctic, and not all available datasets are readily interoperable. Furthermore, the terrestrial Arctic consists of a diversity of vegetation types, which are generally not well represented in land surface schemes of current Earth system models. This dataset comprises harmonized, standardized and aggregated in-situ observations of surface energy budget components measured at 64 sites on vegetated and glaciated sites north of 60° latitude, in the time period from 1994 till 2021. The surface energy budget components include net radiation, sensible heat flux, latent heat flux, ground heat flux, net shortwave radiation, net longwave radiation, surface temperature and albedo, which were aggregated to daily mean, minimum and maximum values from hourly and half-hourly measurements. Data were retrieved from the monitoring networks FLUXNET, AmeriFlux, AON, GC-Net and PROMICE.

Description: We present sea ice temperature and salinity data from first-year ice (FYI) and second-year ice (SYI) relevant to the temporal development of sea ice permeability and brine drainage efficiency from the early growth phase in October 2019 to the onset of spring warming in May 2020. Our dataset was collected in the central Arctic Ocean during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) Expedition in 2019 to 2020. MOSAiC was an international transpolar drift expedition in which the German icebreaker RV Polarstern anchored into an ice floe to gain new insights into Arctic climate over a full annual cycle. In October 2019, RV Polarstern moored to an ice floe in the Siberian sector of the Arctic at 85 degrees north and 137 degrees east to begin the drift towards the North Pole and the Fram Strait via the Transpolar Drift Stream. The data presented here were collected during the first three legs of the expedition, so all the coring activities took place on the same floe. The end dates of legs 1, 2, and 3 were 13 December, 24 February, and 4 June, respectively. The dataset contributed to a baseline study entitled, Deciphering the properties of different Arctic ice types during the growth phase of the MOSAiC floes: Implications for future studies. The study highlights downward directed gas pathways in FYI and SYI by inferring sea ice permeability and potential brine release from several time series of temperature and salinity measurements. The physical properties presented in this paper lay the foundation for subsequent analyses on actual gas contents measured in the ice cores, as well as air-ice and ice-ocean gas fluxes. Sea ice cores were collected with a Kovacs Mark II 9 cm diameter corer. To measure ice temperatures, about 4.5 cm deep holes were drilled into the core (intervals varied by site and leg) . The temperatures were measured by a digital thermometer within minutes after the cores were retrieved. The ice cores were placed into pre-labelled plastic sleeves sealed at the bottom end. The ice cores were transported to RV Polarstern and stored in a -20 degrees Celsius freezer. Each of the cores was sub-sampled, melted at room temperature, and processed for salinity within one or two days. The practical salinity was estimated by measuring the electrical conductivity and temperature of the melted samples using a WTW Cond 3151 salinometer equipped with a Tetra-Con 325 four-electrode conductivity cell. The practical salinity represents the the salinity estimated from the electrical conductivity of the solution. The dataset also contains derived variables, including sea ice density, brine volume fraction, and the Rayleigh number.

Description: We present sea ice temperature and salinity data from first-year ice (FYI) and second-year ice (SYI) relevant to the temporal development of sea ice permeability and brine drainage efficiency from the early growth phase in October 2019 to the onset of spring warming in May 2020. Our dataset was collected in the central Arctic Ocean during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) Expedition in 2019 to 2020. MOSAiC was an international transpolar drift expedition in which the German icebreaker RV Polarstern anchored into an ice floe to gain new insights into Arctic climate over a full annual cycle. In October 2019, RV Polarstern moored to an ice floe in the Siberian sector of the Arctic at 85 degrees north and 137 degrees east to begin the drift towards the North Pole and the Fram Strait via the Transpolar Drift Stream. The data presented here were collected during the first three legs of the expedition, so all the coring activities took place on the same floe. The end dates of legs 1, 2, and 3 were 13 December, 24 February, and 4 June, respectively. The dataset contributed to a baseline study entitled, Deciphering the properties of different Arctic ice types during the growth phase of the MOSAiC floes: Implications for future studies. The study highlights downward directed gas pathways in FYI and SYI by inferring sea ice permeability and potential brine release from several time series of temperature and salinity measurements. The physical properties presented in this paper lay the foundation for subsequent analyses on actual gas contents measured in the ice cores, as well as air-ice and ice-ocean gas fluxes. Sea ice cores were collected with a Kovacs Mark II 9 cm diameter corer. To measure ice temperatures, about 4.5 cm deep holes were drilled into the core (intervals varied by site and leg) . The temperatures were measured by a digital thermometer within minutes after the cores were retrieved. The ice cores were placed into pre-labelled plastic sleeves sealed at the bottom end. The ice cores were transported to RV Polarstern and stored in a -20 degrees Celsius freezer. Each of the cores was sub-sampled, melted at room temperature, and processed for salinity within one or two days. The practical salinity was estimated by measuring the electrical conductivity and temperature of the melted samples using a WTW Cond 3151 salinometer equipped with a Tetra-Con 325 four-electrode conductivity cell. The practical salinity represents the the salinity estimated from the electrical conductivity of the solution. The dataset also contains derived variables, including sea ice density, brine volume fraction, and the Rayleigh number.

Description: This dataset describes two 17 m long sediment cores taken from beneath two thermokarst lakes in the Yukechi Alas, Central Yakutia, Russia. The first core was taken from below an Alas thermokarst lake (YU-L7; 61.76397°N, 130.46442°E) and the second core below and Yedoma lake (YU-L15; 61.76086°N, 130.47466°E). The dataset presents biogeochemical and biomarker parameters of sediment cores YU-L7 and YU-L15. Biogeochemical analyses include total carbon (TC) content, total organic carbon (TOC) content, total nitrogen (TN) content. Biomarker parameters include the n-alkane concentration, average chain length (ACL), carbon preference index (CPI), brGDGT concentration, archaeol concentration and the isoGDGT-0 concentration. The n-alkanes were measured in the aliphatic fraction by gas chromatography-mass spectromety using a Trace GC Ultra coupled to a DSQ MS. The branched and isoprenoid glycerol dialkyl glycerol tetraethers, as well as the dialkyl glycerol diether lipid (archaeol) were measured in the NSO fraction using a Shimadzu LC-10AD high-performance liquid chromatograph coupled to a Finnigan TSQ 7000 mass spectrometer via an atmospheric pressure chemical ionization interface. The pH soil is the sediment pH which was assessed by adding 6.12 mL of 0.01 M CaCl~2~ to ~2.5 g dried sediment and measuring with a Multilab 540 (WTW) at 20°C.

Description: We present sea ice temperature and salinity data from first-year ice (FYI) and second-year ice (SYI) relevant to the temporal development of sea ice permeability and brine drainage efficiency from the early growth phase in October 2019 to the onset of spring warming in May 2020. Our dataset was collected in the central Arctic Ocean during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) Expedition in 2019 to 2020. MOSAiC was an international transpolar drift expedition in which the German icebreaker RV Polarstern anchored into an ice floe to gain new insights into Arctic climate over a full annual cycle. In October 2019, RV Polarstern moored to an ice floe in the Siberian sector of the Arctic at 85 degrees north and 137 degrees east to begin the drift towards the North Pole and the Fram Strait via the Transpolar Drift Stream. The data presented here were collected during the first three legs of the expedition, so all the coring activities took place on the same floe. The end dates of legs 1, 2, and 3 were 13 December, 24 February, and 4 June, respectively. The dataset contributed to a baseline study entitled, Deciphering the properties of different Arctic ice types during the growth phase of the MOSAiC floes: Implications for future studies. The study highlights downward directed gas pathways in FYI and SYI by inferring sea ice permeability and potential brine release from several time series of temperature and salinity measurements. The physical properties presented in this paper lay the foundation for subsequent analyses on actual gas contents measured in the ice cores, as well as air-ice and ice-ocean gas fluxes. Sea ice cores were collected with a Kovacs Mark II 9 cm diameter corer. To measure ice temperatures, about 4.5 cm deep holes were drilled into the core (intervals varied by site and leg) . The temperatures were measured by a digital thermometer within minutes after the cores were retrieved. The ice cores were placed into pre-labelled plastic sleeves sealed at the bottom end. The ice cores were transported to RV Polarstern and stored in a -20 degrees Celsius freezer. Each of the cores was sub-sampled, melted at room temperature, and processed for salinity within one or two days. The practical salinity was estimated by measuring the electrical conductivity and temperature of the melted samples using a WTW Cond 3151 salinometer equipped with a Tetra-Con 325 four-electrode conductivity cell. The practical salinity represents the the salinity estimated from the electrical conductivity of the solution. The dataset also contains derived variables, including sea ice density, brine volume fraction, and the Rayleigh number.

Description: Despite the importance of surface energy budgets (SEBs) for land-climate interactions in the Arctic, uncertainties in their prediction persist. In-situ observational data of SEB components - useful for research and model validation - are collected at relatively few sites across the terrestrial Arctic, and not all available datasets are readily interoperable. Furthermore, the terrestrial Arctic consists of a diversity of vegetation types, which are generally not well represented in land surface schemes of current Earth system models. Therefore, we here provide four datasets comprising: 1. Harmonized, standardized and aggregated in situ observations of SEB components at 64 vegetated and glaciated sites north of 60° latitude, in the time period 1994-2021 2. A description of all study sites and associated environmental conditions, including the vegetation types, which correspond to the classification of the Circumpolar Arctic Vegetation Map (CAVM, Raynolds et al. 2019). 3. Data generated in a literature synthesis from 358 study sites on vegetation or glacier (〉=60°N latitude) covered by 148 publications. 4. Metadata, including data contributor information and measurement heights of variables associated with Oehri et al. 2022.

Description: This dataset provides lithological data from ICDP core 5017-1-A, retrieved from the deep northern Dead Sea basin in 2010/11, for the last glacial-interglacial transition (ca. 17-11.5 ka BP). The microfacies of the Lisan Formation was investigated between ~101 and 88.5 m sediment depth below lake floor by continuous thin section microscopy, while additional macroscopic information is provided from core catchers, as well as from over- and underlying sediment sections. Thin sections were prepared following the standard procedure by Brauer and Casanova (2001) that was adjusted for salty sediments. Thin section analyses were performed on overlapping large-scale thin sections using a Zeiss Axiolab pol microscope at magnifications of 50-400x.

Description: This dataset contains observations of water discharge rates and concentrations of dissolved organic carbon (DOC) and dissolved inorganic carbon (DIC) from a polygonal tundra site in the Lena River Delta, Russia. This dataset also contains lateral carbon fluxes of DOC and DIC that were estimated from these observations. Additionally, this dataset contains vertical fluxes of carbon dioxide and methane from the same study site. All observations were recorded on Samoylov Island (N 72.377188, E 126.495144) in the summer of 2014. The abbreviations A1, A2 and B refer to three outflows on the island where the hydrological parameters were observed (A1: N 72.379991, E 126.480886; A2: N 72.380134, E 126.481433; B: N 72.381348, E 126.483482). All outflows were approximately 10 meters. More information can be found in https://doi.org/10.5194/bg-19-3863-2022.

Description: Despite the importance of surface energy budgets (SEBs) for land-climate interactions in the Arctic, uncertainties in their prediction persist. In situ observational data of SEB components - useful for research and model validation - are collected at relatively few sites across the terrestrial Arctic, and not all available datasets are readily interoperable. Furthermore, the terrestrial Arctic consists of a diversity of vegetation types, which are generally not well represented in land surface schemes of current Earth system models. This dataset describes the environmental conditions for 64 tundra and glacier sites (〉=60°N latitude) across the Arctic, for which in situ measurements of surface energy budget components were harmonized (see Oehri et al. 2022). These environmental conditions are (proxies of) potential drivers of SEB-components and could therefore be called SEB-drivers. The associated environmental conditions, include the vegetation types graminoid tundra, prostrate dwarf-shrub tundra, erect-shrub tundra, wetland complexes, barren complexes (≤ 40% horizontal plant cover), boreal peat bogs and glacier. These land surface types (apart from boreal peat bogs) correspond to the main classification units of the Circumpolar Arctic Vegetation Map (CAVM, Raynolds et al. 2019). For each site, additional climatic and biophysical variables are available, including cloud cover, snow cover duration, permafrost characteristics, climatic conditions and topographic conditions.

Description: This dataset contains over 30 marine Electrical Resistivity Tomography (ERT) profiles taken in September 2021 around Tuktoyaktuk Island (NWT / Beaufort Sea, Canada). The measurements were part of the “Mackenzie Delta Permafrost Field Campaign” (mCan2021) within the “Modular Observation solutions for Earth Systems” (MOSES) program. The collected profiles consist of numerous adjacent vertical soundings in a (quasi-symmetric) reciprocal Wenner-Schlumberger array, using a floating cable towed behind a boat. GPS records along the electrode streamer were taken, enabling the improvement of pre- processing by excluding measurements for which the cable was curved and electrode positions deviated too widely. The aim of the study was to determine the depth of the submarine permafrost. Cleaned data is provided in csv format.

Description: This collection contains permafrost related measurements in the Mackenzie Delta, NWT, Canada from the MOSES (Modular Observation Solutions for Earth Systems) field campaign in September 2021. The field campaign was focused on three subaquatic sites: a small thermokarst lake along the ITH just south of Trail Valley Creek, "Lake 3", an elongated lake with known methane occurence in the outer Mackenzie Delta, "Swiss Cheese Lake", and north and south of Tuktoyaktuk Island. At "Swiss Cheese Lake", we measured methane and CO2 concentrations in surface water and in the air above the lake, lake bed temperatures and detailed bathymetry. At "Lake 3" we measured active layer thickness on the lake banks, lake bed temperatures, and detailed bathymetry, as well as an ERT survey to estimate the talik depth below the lake. North and south of Tuktoyaktuk Island, we measured active layer thickness and sea bed temperatures and did an extensive ERT survey to obtain the depth of the subsea permafrost table. An additional passive seismic survey was carried out and the data is available at https://doi.org/10.5880/GIPP.202199.1.

Description: This dataset contains seven Electrical Resistivity Tomography (ERT) profiles taken in September 2021 at “Lake 3”, a thermokarst lake near the Inuvik-Tuktoyaktuk-Highway (ITH), about 50 km north of Inuvik (NWT, Canada). The measurements were part of the “Mackenzie Delta Permafrost Field Campaign” (mCan2021) within the “Modular Observation solutions for Earth Systems” (MOSES) program. The collected profiles consist of numerous adjacent vertical soundings in a (quasi-symmetric) reciprocal Wenner-Schlumberger array. In addition to surveys on the lake, using a floating cable towed behind a boat, two “amphibian” profiles were taken. Starting as purely terrestrial surveys using metal spike electrodes, the cable was then moved towards the lake with some of the electrodes floating on the water surface, and some still on land. The aim of the study was to determine permafrost properties on the land, to detect a possible talik beneath the lake and to especially be able to infer the transition between the two below the shoreline.

Description: Despite the well-known limitations of linear stability theory in describing nonlinear and turbulent flows, it has been found to accurately capture the transitions between certain nonlinear flow behavior. Specifically, the transition in heat flux scaling in rotating convective flows can be well predicted by applying a linear stability analysis to simple profiles of a convective boundary layer. This fact motivates the present study of the linear mechanisms involved in the stability properties of simple convective setups subject to rotation. We look at an idealized two-layer setup and gradually add complexity by including rotation, a bounded domain, and viscosity. The two-layer setup has the advantage of allowing for the use of wave interaction theory, traditionally applied to understand stratified and homogeneous shear flow instabilities, in order to quantify the various physical mechanisms leading to the growth of convective instabilities. We quantitatively show that the physical mechanisms involved in the stabilization of convection by rotation take two different forms acting within the stratified interfacial region, and in the homogeneous mixed layers. The latter of these we associate with the tendency of a rotating flow to develop Taylor columns (TCs). This TC mechanism can lead to both a stabilization or destabilization of the instability and varies depending on the parameters of the problem. A simple criterion is found for classifying the influence of these physical mechanisms.

Description: A shallow subtidal area in the northern Wadden Sea was monitored over 17 years for sediment parameters and macrobenthic fauna using stratified random sampling of a grid of 50 sampling positions. Samples were collected with a Reineck-type box-corer of 0.02 m² surface area, always during preceeded high tide. Granulometric sediment composition was analysed from a sub-sample of each box-core using a diffraction laser particle-size analyser. Macrobenthos (sieved through 1 mm square meshes and fixed in buffered formalin solution) was counted, identified to species level, and the size of hard-shelled individuals measured. The amount of shell detritus was quantified as wet-weight in the benthos samples. From 2003 to 2007 sampling was approximatively monthly and from 2008 to 2013 seasonally. When a new ship with larger drought was put into operation, the number of sampling sites needed to be reduced to 33 from 2014 onwards and sampling frequency was only once per year in autumn.

Description: Offshore wind energy is a steadily growing sector contributing to the worldwide energy production. The impact of these offshore constructions on the marine environment, however, remains unclear in many aspects. In fact, little is known about potential emissions from corrosion protection systems such as organic coatings or galvanic anodes composed of Al and Zn alloys, used to protect offshore structures. In order to assess potential chemical emissions from offshore wind farms and their impact on the marine environment water and sediment samples were taken in the surroundings of offshore wind farms of the German Bight between 25.07.2016 and 02.08.2016. At every sampling station oceanographic parameters were measured directly on board with respective probes of a multimeter covering pH, dissolved oxygen, temperature and conductivity.

Description: Glacier foreland soil flooded by melt water annually during the melting season, altering soil water content or other soil properties. We collected soil samples in the Longxiazailongba Glacier foreland on the Tibetan Plateau in August 2017. Measuring the soil pH, moisture, Ammonium nitrogen (NH4+), Nitrate nitrogen (NO3-), Total Nitrogen (TN), Organic matter (OM), Available phosphorus (AP). Soils were neutral to slight alkaline, and pH of hollows were significantly higher than those in hummock soils. In contrast, available phosphorous was significantly higher in hummock soils than in hollow soils. Besides, we also quanified mcrA and pmoA gene abundances. With measuring methane fluxes in June (pre-melting season) and August (melting season) 2020, we also measured the soil moisture and pH. The results indicate that soil moisture was significantly higher in melting season (August) than in pre-melting season (June).

Description: Stable oxygen and carbon isotopes were measured on (i) the planktic foraminifera species Globigerinoides ruber (white) and alternatively, in samples in which G. ruber was lacking, on Globigerinoides conglobatus; and (ii) the benthic foraminifera species Cibicidoides pachyderma and alternatively, in samples in which C. pachyderma was lacking, on Cibicides lobatulus. 10–15 planktic and 4-6 benthic specimens of the fraction 〉250 μm were selected. Additionally, attention was paid to select specimens of similar size to minimise influences of metabolic effects and changing preferential habitats during ontogeny. For cleaning and removal of sediment, the selected foraminifera were cracked between two glass plates, transferred to a sample cup, covered with ethanol and immerged into an ultrasonic bath for 5–10 s. The sediment brought into suspension was decanted. The procedure was repeated until the ethanol remained clear after the ultrasonic bath. The cleaned foraminifera were reacted with 100% phosphoric acidat 75 °C using a Kiel III online carbonate preparation line connected to a ThermoFinnigan 252 mass spectrometer (Geochemical Laboratory of the GeoZentrum Nordbayern,Germany). Isotopic data are expressed in per mil relative to V-PDB by assigning a δ18O-value of -2.20 ‰ to NBS19, using the standard δ-notation. The reproducibility was checked by replicate analysis of laboratory standards and was found to be better than ±0.05 for δ18O and δ13C (1σ).

Description: A key task in understanding and mapping the complex mass transport pathways and potential transformation processes of contaminants in coastal regions such as the German Bight is to determine and evaluate the most significant contribution sources into coastal areas. Rivers represent one key input source within this context. As part of a river campaign in June 2016, sediment and freshwater samples were taken from the Weser river and its tributaries to identify their elemental and isotopic fingerprint and to investigate potential inputs to the German Bight. At every sampling station physicochemical parameters of the water column were measured directly after sampling with respective probes of a multimeter covering pH, dissolved oxygen, temperature and conductivity.

Description: In order to understand and map the complex mass transport pathways and possible transformation processes of contaminants in coastal regions such as the German Bight, the main coastal contributors must be identified and evaluated. In this context, rivers represent a major input source. In the framework of a river campaign from 20.06.16 till 25.06.2016, sediment and freshwater samples of the Ems and its tributaries were taken to determine their elemental and isotopic fingerprint and to investigate possible inputs into the German Bight. All sediment samples were obtained using a Van Veen grab sampler and were analyzed for their grain size distribution by laser diffraction.

Description: Isotopic measurements of seawater sampled on-board Polarstern research vessel

Description: Isotopic measurements of seawater sampled on-board Polarstern research vessel

Description: Isotopic measurements of seawater sampled on-board Polarstern research vessel

Description: Isotopic measurements of seawater sampled on-board Polarstern research vessel

Description: Isotopic measurements of seawater sampled on-board Polarstern research vessel

Description: A shallow subtidal area in the northern Wadden Sea was monitored for sediment parameters and macrobenthic fauna using stratified random sampling of a grid of 50 sampling positions. Samples were collected with a Reineck-type box-corer of 0.02 m² surface area, macrobenthos (sieved through 1 mm square meshes and fixed in buffered formalin solution) was counted, identified to species level, and the size of hard-shelled individuals measured. This dataset contains the size measurements of 1098 individuals from the five sampling dates in 2012.

Description: A shallow subtidal area in the northern Wadden Sea was monitored for sediment parameters and macrobenthic fauna using stratified random sampling of a grid of 50 sampling positions. Samples were collected with a Reineck-type box-corer of 0.02 m² surface area, macrobenthos (sieved through 1 mm square meshes and fixed in buffered formalin solution) was counted, identified to species level, and the size of hard-shelled individuals measured. This dataset contains the size measurements of 669 individuals from the three sampling dates in 2013.

Description: A shallow subtidal area in the northern Wadden Sea was monitored for sediment parameters and macrobenthic fauna using stratified random sampling of a grid of 50 sampling positions. Samples were collected with a Reineck-type box-corer of 0.02 m² surface area, macrobenthos (sieved through 1 mm square meshes and fixed in buffered formalin solution) was counted, identified to species level, and the size of hard-shelled individuals measured. This dataset contains the size measurements of 259 individuals from the 2017 sampling.

Description: A shallow subtidal area in the northern Wadden Sea was monitored for sediment parameters and macrobenthic fauna using stratified random sampling of a grid of 50 sampling positions. Samples were collected with a Reineck-type box-corer of 0.02 m² surface area, macrobenthos (sieved through 1 mm square meshes and fixed in buffered formalin solution) was counted, identified to species level, and the size of hard-shelled individuals measured. This dataset contains the size measurements of 253 individuals from the 2016 sampling.

Description: Beach porewater and streams at the coastline of Wismar Bay (Germany), southern Baltic Sea were investigated to evaluate the impact of diagenetic element fluxes and different fresh water sources, including submarine groundwater discharge, on the water column of the Wismar Bay (Germany), southern Baltic Sea. Beach porewater at five different sites between 0.4-1.8 m depth was extracted using push-point lances in July-August 2019. In addition, surface waters from four streams draining into the Wismar Bay were sampled at the mixing zone with the Baltic Sea. Both beach porewater and surface waters were analyzed for dissolved concentrations of major and trace elements and selected nutrients using ICP-OES (iCAP, 7400, Duo Thermo Fischer Scientific), dissolved inorganic carbon (DIC) and δ13CDIC by means of Isotope-ratio-monitoring gas mass spectrometry (MAT 253 coupled to a Gasbench II), and δ18OH2O, δ2HH2O using a CRDS system (laser cavity-ring-down-spectroscopy, Picarro L2140- I), and radium isotopes (223Ra, 224Ra) by radium-delayed coincidence counters (RaDeCC).

Description: The aim of this investigation is to characterize the composition of typical fresh groundwater at the shoreline of the Baltic Sea. The fresh waters escaping from beach springs in Meschendorf (Germany), at the southern Baltic Sea, were analyzed for major and trace elements and selected nutrients using ICP-OES (iCAP, 7400, Duo Thermo Fischer Scientific), dissolved inorganic carbon (DIC) and δ13CDIC using a Gas mass spectrometre (MAT 253) coupled to a Gasbench II, and δ18OH2O, δ2HH2O using a CRDS system (laser cavity-ring-down-spectroscopy, Picarro L2140- I).

Description: Short sediment cores were taken at six stations in Wismar Bay, southern Baltic Sea (Germany) in May 2019 using a Rumohr-Lot device. Our aim in this study was to investigate the role of diagenetic element fluxes and different fresh water sources, including submarine groundwater discharge, on the water column in the bay. Porewaters were extracted from the sediment cores by applying the rhizon technique at a resolution between 2 and 5 cm. The porewaters were analyzed for major and trace metals and selected nutrients using a ICP-OES (iCAP, 7400, Duo Thermo Fischer Scientific), total sulphide by a Specord 40 spectrophotometer (Analytik Jena), dissolved inorganic carbon (DIC) and δ13CDIC using an isotope gas mass spectrometre (MAT 253) coupled to a Gasbench II, and δ18OH2O, and δ2HH2O using a CRDS system (laser cavity-ring-down-spectroscopy, Picarro L2140- I). Sediment cores were further sliced at 2 to 4 cm resolution and each freeze-dried solid subsample was analyzed for contents of total carbon, nitrogen, and sulphur using an Elemental Analyzer (Euro Vector EuroEA 3, 052), inorganic carbon using an Elemental Analyzer multi EA (Analytik Jena), total mercury by a DMA-80 analyzer, and HCl-extractable Pb, Mn and Fe using an ICP-OES (iCAP, 7400, Duo Thermo Fischer Scientific).

Description: Short sediment cores were taken at six stations in Wismar Bay, southern Baltic Sea (Germany) in May 2019 using a Rumohr-Lot device. Our aim in this study was to investigate the role of diagenetic element fluxes and different fresh water sources, including submarine groundwater discharge, on the water column in the bay. Porewaters were extracted from the sediment cores by applying the rhizon technique at a resolution between 2 and 5 cm. The porewaters were analyzed for major and trace metals and selected nutrients using a ICP-OES (iCAP, 7400, Duo Thermo Fischer Scientific), total sulphide by a Specord 40 spectrophotometer (Analytik Jena), dissolved inorganic carbon (DIC) and δ13CDIC using an isotope gas mass spectrometre (MAT 253) coupled to a Gasbench II, and δ18OH2O, and δ2HH2O using a CRDS system (laser cavity-ring-down-spectroscopy, Picarro L2140- I). Sediment cores were further sliced at 2 to 4 cm resolution and each freeze-dried solid subsample was analyzed for contents of total carbon, nitrogen, and sulphur using an Elemental Analyzer (Euro Vector EuroEA 3, 052), inorganic carbon using an Elemental Analyzer multi EA (Analytik Jena), total mercury by a DMA-80 analyzer, and HCl-extractable Pb, Mn and Fe using an ICP-OES (iCAP, 7400, Duo Thermo Fischer Scientific).

Description: The measurements were carried out 27 March–6 April 2020 on small ice-covered shallow Lake Vendyurskoe (62.215784N, 33.262784E, North-Western of Russia). Surface area of the lake is 10.4 km2, its mean and maximal depths are 5.3 and 13.4 m. The maximal length of the lake is 7 km; and the average width is 1.5 km. The mooring equipment was deployed on the ice 350 m from the northern shore, with a location depth of ~ 7 m. The measuring complex included a pyranometer placed directly under the ice to measure downwelling irradiance (a M-80m universal pyranometer, produced in Russia, accuracy 1 W m-2, sampling frequency one minute), two Star-shaped pyranometers (Theodor Friderich & Co, Meteorologishe Gerate und Systeme, Germany, accuracy 0.2 W/m2, sampling interval one minute) placed at one meter above ice surface to measure downwelling and upwelling irradiance, thermistor chain (13 temperature sensors TR-1060 RBR, Canada, accuracy ±0.002°C, resolution ±0.00005°C, sampling frequency 10 s; sensors were placed at intervals of 0.5 m, starting from 0.2 m from the ice bottom to a depth of 6.2 m), and two ADCPs (2 MHz HR Aquadopp current velocity profiler, Nortek AS, Norway). The two ADCPs were mounted on a special retaining frame that rigidly fixed the instruments on the ice and to each other. Both devices were installed in a hole with emitters located 3 cm below the lower ice boundary. For the entire measurement period, the devices were set up as follows: signal discreteness was one minute (32 pulses with a frequency of 2 Hz), depth scanning range was 2.875 m (115 cells with a size of 25 mm). To exclude the mutual influence of the two ADCPs, the emitters were set in an asynchronous mode with a 30 s delay. In the first stage of experiment – from 17:00 LT (local time = UTC + 3 h) on 27 March 2020 to 09:30 LT on 30 March 2020 – the ADCPs emitters were located at a distance of 1.5 m from each other, and at a depth of 1.61 m one beam from each of the devices intersected. In the second stage – from 10:00 LT on 30 March 2020 to 10:00 LT on 6 April 2020 – the distance between the emitters was 0.75 m and two pairs of beams intersected at the same depth.

Description: The measurements were carried out 27 March–6 April 2020 on small ice-covered shallow Lake Vendyurskoe (62.215784N, 33.262784E, North-Western of Russia). Surface area of the lake is 10.4 km2, its mean and maximal depths are 5.3 and 13.4 m. The maximal length of the lake is 7 km; and the average width is 1.5 km. The mooring equipment was deployed on the ice 350 m from the northern shore, with a location depth of ~ 7 m. The measuring complex included a pyranometer placed directly under the ice to measure downwelling irradiance (a M-80m universal pyranometer, produced in Russia, accuracy 1 W m-2, sampling frequency one minute), two Star-shaped pyranometers (Theodor Friderich & Co, Meteorologishe Gerate und Systeme, Germany, accuracy 0.2 W/m2, sampling interval one minute) placed at one meter above ice surface to measure downwelling and upwelling irradiance, thermistor chain (13 temperature sensors TR-1060 RBR, Canada, accuracy ±0.002°C, resolution ±0.00005°C, sampling frequency 10 s; sensors were placed at intervals of 0.5 m, starting from 0.2 m from the ice bottom to a depth of 6.2 m), and two ADCPs (2 MHz HR Aquadopp current velocity profiler, Nortek AS, Norway). The two ADCPs were mounted on a special retaining frame that rigidly fixed the instruments on the ice and to each other. Both devices were installed in a hole with emitters located 3 cm below the lower ice boundary. For the entire measurement period, the devices were set up as follows: signal discreteness was one minute (32 pulses with a frequency of 2 Hz), depth scanning range was 2.875 m (115 cells with a size of 25 mm). To exclude the mutual influence of the two ADCPs, the emitters were set in an asynchronous mode with a 30 s delay. In the first stage of experiment – from 17:00 LT (local time = UTC + 3 h) on 27 March 2020 to 09:30 LT on 30 March 2020 – the ADCPs emitters were located at a distance of 1.5 m from each other, and at a depth of 1.61 m one beam from each of the devices intersected. In the second stage – from 10:00 LT on 30 March 2020 to 10:00 LT on 6 April 2020 – the distance between the emitters was 0.75 m and two pairs of beams intersected at the same depth.

Description: The measurements were carried out 27 March–6 April 2020 on small ice-covered shallow Lake Vendyurskoe (62.215784N, 33.262784E, North-Western of Russia). Surface area of the lake is 10.4 km2, its mean and maximal depths are 5.3 and 13.4 m. The maximal length of the lake is 7 km; and the average width is 1.5 km. The mooring equipment was deployed on the ice 350 m from the northern shore, with a location depth of ~ 7 m. The measuring complex included a pyranometer placed directly under the ice to measure downwelling irradiance (a M-80m universal pyranometer, produced in Russia, accuracy 1 W m-2, sampling frequency one minute), two Star-shaped pyranometers (Theodor Friderich & Co, Meteorologishe Gerate und Systeme, Germany, accuracy 0.2 W/m2, sampling interval one minute) placed at one meter above ice surface to measure downwelling and upwelling irradiance, thermistor chain (13 temperature sensors TR-1060 RBR, Canada, accuracy ±0.002°C, resolution ±0.00005°C, sampling frequency 10 s; sensors were placed at intervals of 0.5 m, starting from 0.2 m from the ice bottom to a depth of 6.2 m), and two ADCPs (2 MHz HR Aquadopp current velocity profiler, Nortek AS, Norway). The two ADCPs were mounted on a special retaining frame that rigidly fixed the instruments on the ice and to each other. Both devices were installed in a hole with emitters located 3 cm below the lower ice boundary. For the entire measurement period, the devices were set up as follows: signal discreteness was one minute (32 pulses with a frequency of 2 Hz), depth scanning range was 2.875 m (115 cells with a size of 25 mm). To exclude the mutual influence of the two ADCPs, the emitters were set in an asynchronous mode with a 30 s delay. In the first stage of experiment – from 17:00 LT (local time = UTC + 3 h) on 27 March 2020 to 09:30 LT on 30 March 2020 – the ADCPs emitters were located at a distance of 1.5 m from each other, and at a depth of 1.61 m one beam from each of the devices intersected. In the second stage – from 10:00 LT on 30 March 2020 to 10:00 LT on 6 April 2020 – the distance between the emitters was 0.75 m and two pairs of beams intersected at the same depth.

Description: The measurements were carried out 27 March–6 April 2020 on small ice-covered shallow Lake Vendyurskoe (62.215784N, 33.262784E, North-Western of Russia). Surface area of the lake is 10.4 km2, its mean and maximal depths are 5.3 and 13.4 m. The maximal length of the lake is 7 km; and the average width is 1.5 km. The mooring equipment was deployed on the ice 350 m from the northern shore, with a location depth of ~ 7 m. The measuring complex included a pyranometer placed directly under the ice to measure downwelling irradiance (a M-80m universal pyranometer, produced in Russia, accuracy 1 W m-2, sampling frequency one minute), two Star-shaped pyranometers (Theodor Friderich & Co, Meteorologishe Gerate und Systeme, Germany, accuracy 0.2 W/m2, sampling interval one minute) placed at one meter above ice surface to measure downwelling and upwelling irradiance, thermistor chain (13 temperature sensors TR-1060 RBR, Canada, accuracy ±0.002°C, resolution ±0.00005°C, sampling frequency 10 s; sensors were placed at intervals of 0.5 m, starting from 0.2 m from the ice bottom to a depth of 6.2 m), and two ADCPs (2 MHz HR Aquadopp current velocity profiler, Nortek AS, Norway). The two ADCPs were mounted on a special retaining frame that rigidly fixed the instruments on the ice and to each other. Both devices were installed in a hole with emitters located 3 cm below the lower ice boundary. For the entire measurement period, the devices were set up as follows: signal discreteness was one minute (32 pulses with a frequency of 2 Hz), depth scanning range was 2.875 m (115 cells with a size of 25 mm). To exclude the mutual influence of the two ADCPs, the emitters were set in an asynchronous mode with a 30 s delay. In the first stage of experiment – from 17:00 LT (local time = UTC + 3 h) on 27 March 2020 to 09:30 LT on 30 March 2020 – the ADCPs emitters were located at a distance of 1.5 m from each other, and at a depth of 1.61 m one beam from each of the devices intersected. In the second stage – from 10:00 LT on 30 March 2020 to 10:00 LT on 6 April 2020 – the distance between the emitters was 0.75 m and two pairs of beams intersected at the same depth.

Description: The measurements were carried out 27 March–6 April 2020 on small ice-covered shallow Lake Vendyurskoe (62.215784N, 33.262784E, North-Western of Russia). Surface area of the lake is 10.4 km2, its mean and maximal depths are 5.3 and 13.4 m. The maximal length of the lake is 7 km; and the average width is 1.5 km. The mooring equipment was deployed on the ice 350 m from the northern shore, with a location depth of ~ 7 m. The measuring complex included a pyranometer placed directly under the ice to measure downwelling irradiance (a M-80m universal pyranometer, produced in Russia, accuracy 1 W m-2, sampling frequency one minute), two Star-shaped pyranometers (Theodor Friderich & Co, Meteorologishe Gerate und Systeme, Germany, accuracy 0.2 W/m2, sampling interval one minute) placed at one meter above ice surface to measure downwelling and upwelling irradiance, thermistor chain (13 temperature sensors TR-1060 RBR, Canada, accuracy ±0.002°C, resolution ±0.00005°C, sampling frequency 10 s; sensors were placed at intervals of 0.5 m, starting from 0.2 m from the ice bottom to a depth of 6.2 m), and two ADCPs (2 MHz HR Aquadopp current velocity profiler, Nortek AS, Norway). The two ADCPs were mounted on a special retaining frame that rigidly fixed the instruments on the ice and to each other. Both devices were installed in a hole with emitters located 3 cm below the lower ice boundary. For the entire measurement period, the devices were set up as follows: signal discreteness was one minute (32 pulses with a frequency of 2 Hz), depth scanning range was 2.875 m (115 cells with a size of 25 mm). To exclude the mutual influence of the two ADCPs, the emitters were set in an asynchronous mode with a 30 s delay. In the first stage of experiment – from 17:00 LT (local time = UTC + 3 h) on 27 March 2020 to 09:30 LT on 30 March 2020 – the ADCPs emitters were located at a distance of 1.5 m from each other, and at a depth of 1.61 m one beam from each of the devices intersected. In the second stage – from 10:00 LT on 30 March 2020 to 10:00 LT on 6 April 2020 – the distance between the emitters was 0.75 m and two pairs of beams intersected at the same depth.

Description: The measurements were carried out 27 March–6 April 2020 on small ice-covered shallow Lake Vendyurskoe (62.215784N, 33.262784E, North-Western of Russia). Surface area of the lake is 10.4 km2, its mean and maximal depths are 5.3 and 13.4 m. The maximal length of the lake is 7 km; and the average width is 1.5 km. The mooring equipment was deployed on the ice 350 m from the northern shore, with a location depth of ~ 7 m. The measuring complex included a pyranometer placed directly under the ice to measure downwelling irradiance (a M-80m universal pyranometer, produced in Russia, accuracy 1 W m-2, sampling frequency one minute), two Star-shaped pyranometers (Theodor Friderich & Co, Meteorologishe Gerate und Systeme, Germany, accuracy 0.2 W/m2, sampling interval one minute) placed at one meter above ice surface to measure downwelling and upwelling irradiance, thermistor chain (13 temperature sensors TR-1060 RBR, Canada, accuracy ±0.002°C, resolution ±0.00005°C, sampling frequency 10 s; sensors were placed at intervals of 0.5 m, starting from 0.2 m from the ice bottom to a depth of 6.2 m), and two ADCPs (2 MHz HR Aquadopp current velocity profiler, Nortek AS, Norway). The two ADCPs were mounted on a special retaining frame that rigidly fixed the instruments on the ice and to each other. Both devices were installed in a hole with emitters located 3 cm below the lower ice boundary. For the entire measurement period, the devices were set up as follows: signal discreteness was one minute (32 pulses with a frequency of 2 Hz), depth scanning range was 2.875 m (115 cells with a size of 25 mm). To exclude the mutual influence of the two ADCPs, the emitters were set in an asynchronous mode with a 30 s delay. In the first stage of experiment – from 17:00 LT (local time = UTC + 3 h) on 27 March 2020 to 09:30 LT on 30 March 2020 – the ADCPs emitters were located at a distance of 1.5 m from each other, and at a depth of 1.61 m one beam from each of the devices intersected. In the second stage – from 10:00 LT on 30 March 2020 to 10:00 LT on 6 April 2020 – the distance between the emitters was 0.75 m and two pairs of beams intersected at the same depth.

Description: Data on whale distribution and abundance in the polar oceans is rather sparse, as implementing the standard surveying method, line-transect surveys, is challenging and costly. To overcome this problem, we initiated a program to electronically log all opportunistic cetacean sightings during all Polarstern expeditions through the nautical officer on watch. Opportunistic (visual) sightings by naked eye were logged during Polarstern Cruise PS89 (Cape Town – Cape Town) by the nautical officer on duty using a customized Software package (WALOG, WhAleLOGger) installed on a touch screen laptop located on the ship's bridge. Species were identified by naked eye or handheld binoculars (7x50) to the lowest possible taxonomical level and assigned a “certainty” level of identification. The number of animals were counted if possible or estimated for larger groups. Whenever identification to species level was not possible, the next identifiable taxonomical category was assigned. Information on sighting position, date and time are automatically transferred from the ship's DAVIS-Ship System (https://dship.awi.de/) to the WALOG software at the time of logging. Photographs were taken if possible for retrospective analysis. All data of acquired sightings were retrospectively validated by a marine biologist and converted to a standard format. To this end, plausibility of sighting time, location, standardization of species names, eventual comments added at the time of sighting, as well as additional information such as photographs (if available) were checked either to verify or improve species identification. Datasets are used in species distribution modelling and to inform interested parties about occurrences.

Description: Data on whale distribution and abundance in the polar oceans is rather sparse, as implementing the standard surveying method, line-transect surveys, is challenging and costly. To overcome this problem, we initiated a program to electronically log all opportunistic cetacean sightings during all Polarstern expeditions through the nautical officer on watch. Opportunistic (visual) sightings by naked eye were logged during Polarstern Cruise PS121 (Bremerhaven -Tromsø ) by the nautical officer on duty using a customized Software package (WALOG, WhAleLOGger) installed on a touch screen laptop located on the ship's bridge. Species were identified by naked eye or handheld binoculars (7x50) to the lowest possible taxonomical level and assigned a “certainty” level of identification. The number of animals were counted if possible or estimated for larger groups. Whenever identification to species level was not possible, the next identifiable taxonomical category was assigned. Information on sighting position, date and time are automatically transferred from the ship's DAVIS-Ship System (https://dship.awi.de/) to the WALOG software at the time of logging. Photographs were taken if possible for retrospective analysis. All data of acquired sightings were retrospectively validated by a marine biologist and converted to a standard format. To this end, plausibility of sighting time, location, standardization of species names, eventual comments added at the time of sighting, as well as additional information such as photographs (if available) were checked either to verify or improve species identification. Datasets are used in species distribution modelling and to inform interested parties about occurrences.

Description: Data on whale distribution and abundance in the polar oceans is rather sparse, as implementing the standard surveying method, line-transect surveys, is challenging and costly. To overcome this problem, we initiated a program to electronically log all opportunistic cetacean sightings during all Polarstern expeditions through the nautical officer on watch. Opportunistic (visual) sightings by naked eye were logged during Polarstern Cruise PS83 (Cape Town – Bremerhaven) by the nautical officer on duty using a customized Software package (WALOG, WhAleLOGger) installed on a touch screen laptop located on the ship's bridge. Species were identified by naked eye or handheld binoculars (7x50) to the lowest possible taxonomical level and assigned a “certainty” level of identification. The number of animals were counted if possible or estimated for larger groups. Whenever identification to species level was not possible, the next identifiable taxonomical category was assigned. Information on sighting position, date and time are automatically transferred from the ship's DAVIS-Ship System (https://dship.awi.de/) to the WALOG software at the time of logging. Photographs were taken if possible for retrospective analysis. All data of acquired sightings were retrospectively validated by a marine biologist and converted to a standard format. To this end, plausibility of sighting time, location, standardization of species names, eventual comments added at the time of sighting, as well as additional information such as photographs (if available) were checked either to verify or improve species identification. Datasets are used in species distribution modelling and to inform interested parties about occurrences.

Description: Isotopic measurements of seawater sampled on-board Polarstern research vessel

Description: Isotopic measurements of seawater sampled on-board Polarstern research vessel

Description: Isotopic measurements of seawater sampled on-board Polarstern research vessel

Description: Isotopic measurements of seawater sampled on-board Polarstern research vessel

Description: Isotopic measurements of seawater sampled on-board Polarstern research vessel

Description: Isotopic measurements of seawater sampled on-board Polarstern research vessel

Description: Isotopic measurements of seawater sampled on-board Polarstern research vessel

Description: Isotopic measurements of seawater sampled on-board Polarstern research vessel

Description: Isotopic measurements of seawater sampled on-board Polarstern research vessel

Description: Isotopic measurements of seawater sampled on-board Polarstern research vessel

Description: Isotopic measurements of seawater sampled on-board Polarstern research vessel

Description: Isotopic measurements of seawater sampled on-board Polarstern research vessel

Description: A shallow subtidal area in the northern Wadden Sea was monitored for sediment parameters and macrobenthic fauna using stratified random sampling of a grid of 50 sampling positions. Samples were collected with a Reineck-type box-corer of 0.02 m² surface area, macrobenthos (sieved through 1 mm square meshes and fixed in buffered formalin solution) was counted, identified to species level, and the size of hard-shelled individuals measured. This dataset contains the size measurements of 1629 individuals from the four sampling dates in 2003.

Description: A shallow subtidal area in the northern Wadden Sea was monitored for sediment parameters and macrobenthic fauna using stratified random sampling of a grid of 50 sampling positions. Samples were collected with a Reineck-type box-corer of 0.02 m² surface area, macrobenthos (sieved through 1 mm square meshes and fixed in buffered formalin solution) was counted, identified to species level, and the size of hard-shelled individuals measured. This dataset contains the size measurements of 3198 individuals from the 11 sampling dates in 2004.

Description: A shallow subtidal area in the northern Wadden Sea was monitored for sediment parameters and macrobenthic fauna using stratified random sampling of a grid of 50 sampling positions. Samples were collected with a Reineck-type box-corer of 0.02 m² surface area, macrobenthos (sieved through 1 mm square meshes and fixed in buffered formalin solution) was counted, identified to species level, and the size of hard-shelled individuals measured. This dataset contains the size measurements of 15918 individuals from the 10 sampling dates in 2005.

Description: A shallow subtidal area in the northern Wadden Sea was monitored for sediment parameters and macrobenthic fauna using stratified random sampling of a grid of 50 sampling positions. Samples were collected with a Reineck-type box-corer of 0.02 m² surface area, macrobenthos (sieved through 1 mm square meshes and fixed in buffered formalin solution) was counted, identified to species level, and the size of hard-shelled individuals measured. This dataset contains the size measurements of 1990 individuals from the nine sampling dates in 2006.

Description: A shallow subtidal area in the northern Wadden Sea was monitored for sediment parameters and macrobenthic fauna using stratified random sampling of a grid of 50 sampling positions. Samples were collected with a Reineck-type box-corer of 0.02 m² surface area, macrobenthos (sieved through 1 mm square meshes and fixed in buffered formalin solution) was counted, identified to species level, and the size of hard-shelled individuals measured. This dataset contains the size measurements of 3555 individuals from the 10 sampling dates in 2007.

Description: A shallow subtidal area in the northern Wadden Sea was monitored for sediment parameters and macrobenthic fauna using stratified random sampling of a grid of 50 sampling positions. Samples were collected with a Reineck-type box-corer of 0.02 m² surface area, macrobenthos (sieved through 1 mm square meshes and fixed in buffered formalin solution) was counted, identified to species level, and the size of hard-shelled individuals measured. This dataset contains the size measurements of 734 individuals from the three sampling dates in 2009.

Description: A shallow subtidal area in the northern Wadden Sea was monitored for sediment parameters and macrobenthic fauna using stratified random sampling of a grid of 50 sampling positions. Samples were collected with a Reineck-type box-corer of 0.02 m² surface area, macrobenthos (sieved through 1 mm square meshes and fixed in buffered formalin solution) was counted, identified to species level, and the size of hard-shelled individuals measured. This dataset contains the size measurements of 672 individuals from the three sampling dates in 2010.

Description: A shallow subtidal area in the northern Wadden Sea was monitored for sediment parameters and macrobenthic fauna using stratified random sampling of a grid of 50 sampling positions. Samples were collected with a Reineck-type box-corer of 0.02 m² surface area, macrobenthos (sieved through 1 mm square meshes and fixed in buffered formalin solution) was counted, identified to species level, and the size of hard-shelled individuals measured. This dataset contains the size measurements of 1018 individuals from the five sampling dates in 2011.

Description: A shallow subtidal area in the northern Wadden Sea was monitored for sediment parameters and macrobenthic fauna using stratified random sampling of a grid of 50 sampling positions. Samples were collected with a Reineck-type box-corer of 0.02 m² surface area, macrobenthos (sieved through 1 mm square meshes and fixed in buffered formalin solution) was counted, identified to species level, and the size of hard-shelled individuals measured. This dataset contains the size measurements of 1072 individuals from the five sampling dates in 2008.

Description: A shallow subtidal area in the northern Wadden Sea was monitored for sediment parameters and macrobenthic fauna using stratified random sampling of a grid of 50 sampling positions. Samples were collected with a Reineck-type box-corer of 0.02 m² surface area, macrobenthos (sieved through 1 mm square meshes and fixed in buffered formalin solution) was counted, identified to species level, and the size of hard-shelled individuals measured. This dataset contains the size measurements of 1055 individuals from the 2014 sampling.

Description: A shallow subtidal area in the northern Wadden Sea was monitored for sediment parameters and macrobenthic fauna using stratified random sampling of a grid of 50 sampling positions. Samples were collected with a Reineck-type box-corer of 0.02 m² surface area, macrobenthos (sieved through 1 mm square meshes and fixed in buffered formalin solution) was counted, identified to species level, and the size of hard-shelled individuals measured. This dataset contains the size measurements of 294 individuals from the 2015 sampling.

Description: A shallow subtidal area in the northern Wadden Sea was monitored for sediment parameters and macrobenthic fauna using stratified random sampling of a grid of 50 sampling positions. Samples were collected with a Reineck-type box-corer of 0.02 m² surface area, macrobenthos (sieved through 1 mm square meshes and fixed in buffered formalin solution) was counted, identified to species level, and the size of hard-shelled individuals measured. This dataset contains the size measurements of 120 individuals from the 2018 sampling.

Description: A shallow subtidal area in the northern Wadden Sea was monitored for sediment parameters and macrobenthic fauna using stratified random sampling of a grid of 50 sampling positions. Samples were collected with a Reineck-type box-corer of 0.02 m² surface area, macrobenthos (sieved through 1 mm square meshes and fixed in buffered formalin solution) was counted, identified to species level, and the size of hard-shelled individuals measured. This dataset contains the size measurements of 134 individuals from the 2019 sampling.

Description: The measurements were carried out 27 March–6 April 2020 on small ice-covered shallow Lake Vendyurskoe (62.215784N, 33.262784E, North-Western of Russia). Surface area of the lake is 10.4 km2, its mean and maximal depths are 5.3 and 13.4 m. The maximal length of the lake is 7 km; and the average width is 1.5 km. The mooring equipment was deployed on the ice 350 m from the northern shore, with a location depth of ~ 7 m. The measuring complex included a pyranometer placed directly under the ice to measure downwelling irradiance (a M-80m universal pyranometer, produced in Russia, accuracy 1 W m-2, sampling frequency one minute), two Star-shaped pyranometers (Theodor Friderich & Co, Meteorologishe Gerate und Systeme, Germany, accuracy 0.2 W/m2, sampling interval one minute) placed at one meter above ice surface to measure downwelling and upwelling irradiance, thermistor chain (13 temperature sensors TR-1060 RBR, Canada, accuracy ±0.002°C, resolution ±0.00005°C, sampling frequency 10 s; sensors were placed at intervals of 0.5 m, starting from 0.2 m from the ice bottom to a depth of 6.2 m), and two ADCPs (2 MHz HR Aquadopp current velocity profiler, Nortek AS, Norway). The two ADCPs were mounted on a special retaining frame that rigidly fixed the instruments on the ice and to each other. Both devices were installed in a hole with emitters located 3 cm below the lower ice boundary. For the entire measurement period, the devices were set up as follows: signal discreteness was one minute (32 pulses with a frequency of 2 Hz), depth scanning range was 2.875 m (115 cells with a size of 25 mm). To exclude the mutual influence of the two ADCPs, the emitters were set in an asynchronous mode with a 30 s delay. In the first stage of experiment – from 17:00 LT (local time = UTC + 3 h) on 27 March 2020 to 09:30 LT on 30 March 2020 – the ADCPs emitters were located at a distance of 1.5 m from each other, and at a depth of 1.61 m one beam from each of the devices intersected. In the second stage – from 10:00 LT on 30 March 2020 to 10:00 LT on 6 April 2020 – the distance between the emitters was 0.75 m and two pairs of beams intersected at the same depth.