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: 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: Surface air temperature measurements obtained from different sensors are used to construct a unique time series with one minute time-interval. Apart from differences in design and environmental exposition, periods of missing data also exist in the data series of each sensor. A primary data set was selected in terms of quality and temporal extension. A combination of two different techniques is applied to complete this data set: one is based on the autocorrelation of the series and the other on measurements taken from other sensors. The resulting values constitute a complete series of surface air temperature at AGGO.

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: Presented are analytical data from lacustrine sediment cores, retrieved from Lake Nam Co (Tibetan Plateau). The sediment core is a composite of one gravity core, taken with a Rumohr-Meischner gravity corer (63 mm diameter) and a piston core, retrieved using an uwitec piston coring system (http://www.uwitec.at; 90 mm diameter). The composite core labelled 〈NC 08/01〉 comprises a total length of 10.378 m. The cores were obtained at N 30.737417, E 090.790333 at a water depth of 93 m on 2008-09-15. The purpose of obtaining this sediment core was to establish a high-resolution record of climate (monsoonal) and environmental change using multiple proxy data. The dataset comprises analytical data based on sedimentological, inorganic geochemical, mineralogical and isotope-geochemical methods. Specifically: sediment water content & density; magnetic susceptibility; particel size data; quantitative inorganic geochemical data (ICP-OES aqua regia and HCL digestions); semi-quantitative XRF elemental data; carbon, nitrogen, sulfur contents; qualitative mineralogical data; bulk sediment stable carbon and oxygen isotope data.

Description: This data set is part of a larger data harmonization effort to make lake sediment core data machine readable and comparable. Here we standardized X-ray fluorescence line scanning (XRF)-based element data of sediment core EN18208, retrieved in 2018 from Lake Ilirney (Chukotka, Russia) at 10.76 m water depth. The glacial lake Ilirney is situated in the forest tundra mountain area and has one outflow, one main inflow and several smaller inflows. It lies at an elevation of ca. 428 m a.s.l. with a surface area of ca. 30 km2 and a maximum lake water depth of estimated 44 m. The 10.76 m sediment core was retrieved by a UWITEC piston corer during the RU-Land_2018_Chukotka expedition of the Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research (AWI, Germany, Potsdam) in cooperation with the North Eastern Federal State University (NEFU, Russia, Yakutsk). The downcore elemental composition was measured using an AVAATECH x-ray fluorescence core scanner at Bundesanstalt für Geowissenschaften und Rohstoffe (BGR) in Berlin, Spandau.

Description: This data set is part of a larger data harmonization effort to make lake sediment core data machine readable and comparable. Here we standardized radiocarbon and OSL age data of sediment core EN18208, retrieved in 2018 from Lake Ilirney (Chukotka, Russia) at 10.76 m water depth. The glacial lake Ilirney is situated in the forest tundra mountain area and has one outflow, one main inflow and several smaller inflows. It lies at an elevation of ca. 428 m a.s.l. with a surface area of ca. 30 km2 and a maximum lake water depth of estimated 44 m. The 10.76 m sediment core was retrieved by a UWITEC piston corer during the RU-Land_2018_Chukotka expedition of the Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research (AWI, Germany, Potsdam) in cooperation with the North Eastern Federal State University (NEFU, Russia, Yakutsk). Radiocarbon data have been analysed from bulk sediment samples in Bremerhaven at the MICADAS laboratory. Optically stimulated luminescence (OSL) dating was performed at the Royal Holloway Luminescence Laboratory using a Risø TL/OSL-DA-15 automated dating system.

Description: A 25-cm long predominantly aragonite stalagmite was collected November 2, 2005 from Dharamjali Cave (29.5°N, 80.2°E) in the central Himalayas. This dataset contains stable isotope, trace element, XRF, U/Th dating, and dripwater data. The age model spans 4.2 to 2.3 ka BP, and the dataset records seasonal shifts in hydroclimate from 4.2 to 3.1 ka BP. Using the DHAR-1A half of the speleothem, 750 samples were milled at 100–300 µm resolution for stable isotope analysis (δ18O and δ13C) and analyzed at GFZ Potsdam. Further high-resolution stable isotope analysis at the University of Cambridge included 876 samples from the bottom 4 cm of the mirroring slab DHAR-1B, covering c. 4.2–3.6 ka BP. The δ44/40Ca measurements were made on 60 aragonite samples of aragonite and 1 calcite sample milled between 4.2 and 2.8 ka BP. The elemental composition of DHAR-1B was determined first with an Avaatech XRF scanner at the University of Cambridge, and later using laser ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS) at the University of Waikato. U-series dating was performed at Caltech on 22 samples. Twelve U-series ages (between 2.55 and 4.14 ka BP) were used to construct the age models, using ensembles of 2000 Monte Carlo simulations for each proxy using the MATLAB-based COPRA script (Breitenbach et al., 2012, https://doi.org/10.5194/cp-8-1765-2012).

Description: This data set is part of a larger data harmonization effort to make lake sediment core data machine readable and comparable. Here we standardized grain size element data of sediment core EN18208, retrieved in 2018 from Lake Ilirney (Chukotka, Russia) at 10.76 m water depth. The glacial lake Ilirney is situated in the forest tundra mountain area and has one outflow, one main inflow and several smaller inflows. It lies at an elevation of ca. 428 m a.s.l. with a surface area of ca. 30 km2 and a maximum lake water depth of estimated 44 m. The 10.76 m sediment core was retrieved by a UWITEC piston corer during the RU-Land_2018_Chukotka expedition of the Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research (AWI, Germany, Potsdam) in cooperation with the North Eastern Federal State University (NEFU, Russia, Yakutsk). Grain-size was measured using a Malvern Mastersizer 3000 laser diffraction particle analyser.

Description: This data set is part of a larger data harmonization effort to make lake sediment core data machine readable and comparable. Here we standardized mineral data of sediment core EN18208, retrieved in 2018 from Lake Ilirney (Chukotka, Russia) at 10.76 m water depth. The glacial lake Ilirney is situated in the forest tundra mountain area and has one outflow, one main inflow and several smaller inflows. It lies at an elevation of ca. 428 m a.s.l. with a surface area of ca. 30 km2 and a maximum lake water depth of estimated 44 m. The 10.76 m sediment core was retrieved by a UWITEC piston corer during the RU-Land_2018_Chukotka expedition of the Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research (AWI, Germany, Potsdam) in cooperation with the North Eastern Federal State University (NEFU, Russia, Yakutsk). Bulk mineralogy was analysed by (x-ray diffractometry (XRD) using a (PHILIPS, Netherlands) PW1820 goniometer.

Description: This data set is part of a larger data harmonization effort to make lake sediment core data machine readable and comparable. Here we standardized radiocarbon and OSL age data of sediment core EN18208, retrieved in 2018 from Lake Ilirney (Chukotka, Russia) at 10.76 m water depth. The glacial lake Ilirney is situated in the forest tundra mountain area and has one outflow, one main inflow and several smaller inflows. It lies at an elevation of ca. 428 m a.s.l. with a surface area of ca. 30 km2 and a maximum lake water depth of estimated 44 m. The 10.76 m sediment core was retrieved by a UWITEC piston corer during the RU-Land_2018_Chukotka expedition of the Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research (AWI, Germany, Potsdam) in cooperation with the North Eastern Federal State University (NEFU, Russia, Yakutsk). Water content and organic matter was analysed at AWI Potsdam. Dried and milled samples were analysed using a Vario EL III carbon-nitrogen-sulphur analyser. Organic carbon content was determined using a Vario MAX C analyser.

Description: Surface air temperature measurements obtained from different sensors are used to construct a unique time series with one minute time-interval. Apart from differences in design and environmental exposition, periods of missing data also exist in the data series of each sensor. A primary data set was selected in terms of quality and temporal extension. A combination of two different techniques is applied to complete this data set: one is based on the autocorrelation of the series and the other on measurements taken from other sensors. The resulting values constitute a complete series of surface air temperature at AGGO.

Description: This dataset contain stable isotope values for water samples collected ~weekly from the Rio Bermejo at the Lavalle bridge (-25.6513, -60.1277) from March 2016 to February 2018. Water samples were filtered to 0.2 micron using a custom filtration device. We measured d2H and d18O on a Picarro L-2140i Cavity Ring-Down Spectrometer at the GFZ Potsdam. Measurements were made in duplicate, normalized to the Vienna Standard Mean Ocean Water (VSMOW), and analytical uncertainty is reported as one standard deviation from the mean. River discharge was measured at the El Colorado gauging station, which is ~100 km down slope from the sampling location.

Description: This dataset provides the geochemistry data for the Holocene sediment sequence retrieved from Lake Uddelermeer (The Netherlands) in 2012. Additionally, alkane concentrations for a set of modern leaf samples are provided. Concentrations of fossil alkanes, GDGTs as well as elemental (C, N, S, H) and compound-specific delta Deuterium measurements are presented against both depth (cm) and age (cal yr. BP). A total of 59 samples were analysed. Modern leaf alkane concentrations are presented as concentrations, 10 samples were analysed. The geochemical data provides information about regional vegetation change as well as changes in effective precipitation. It was produced to inform on the age and duration of major environmental transitions during the middle and late Holocene. Cores were retrieved from the lake using a 3-m long handheld piston corer deployed from a floating coring platform during field work in April and May 2012. Samples were obtained from splits of the core and processed in the laboratory of the University of Amsterdam (the Netherlands) using standard protocols (CNHS, alkane concentrations), the laboratory of Utrecht University (the Netherlands; GDGT concentrations) and at GFZ Potsdam (Germany; delta Deuterium). Name of the Campaign: UDD Event Label: UDD-E Method: Uwitec piston corer Latitude: 52.24652778 Longitude: 5.76097222 Elevation: 24m asl Date/Time of event: 2012-05-01T14:00:00 Further information about event: Lake sediment sequence retrieved using a 60 mm piston corer deployed from a floating platform.

Description: Water samples were filtered to 0.2 micron prior to measurement. Samples for cation analysis were acidified in the field to pH 〈 2 using 6N HNO3. Cation concentrations were measured with a Varian 720 inductively coupled plasma optical emission spectrometer (ICP-OES) at the GFZ Helmholtz Laboratory for the Geochemistry of the Earth Surface (HELGES), using SLRS-5 (Saint-Laurent River Surface, National Research Council - Conseil National de Recherches Canada) and USGS M212 and USGS T187 as external standards. We corrected for instrument drift by measuring an internal standard (GFZ-RW1) every 10 samples and we determined measurement uncertainty using calibration curve uncertainty. Anion concentrations were measured with a Dionex ICS1100 Ion Chromatograph, using USGS standards M206 and M212 as external standards for quality control, with uncertainty determined from triplicate analysis. We corrected cation concentrations for cyclic salt inputs following Bickle et al. (2005, doi:10.1016/j.gca.2004.11.019).

Description: This dataset reports measurements from a laboratory incubation of soils sourced from a boreal peatland and surrounding habitats (Siikaneva Bog, Finland). In August 2021, soil cores were collected from three habitat zones: a well-drained upland forest, an intermediate margin ecotone, and a Sphagnum moss bog. The cores from each habitat were taken from surface to approximately 50cm below surface using an Eijelkamp peat corer and subdivided by soil horizon. The samples were then incubated anaerobically for 140 days in three temperature treatment groups (0, 4, 20°C). Subsamples of the incubations headspace (250 µL) were measured on a gas chromatograph (7890A, Agilent Technologies, USA) with flame ionization detection (FID) for CO2 and CH4 concentrations. The rate of respiration from the samples were calculated per gram carbon and per gram soil as described in the method of Robertson., et al. (1999) and reported here, along with other relevant parameters.

Description: Data underlying figures 1, 2, 3 and 5. Figure 1: Monthly mass changes of the Greenland Ice Sheet from GRACE/GRACE-FO and SMB-D (2003-2019) Figure 2: Biennial mass balance and its components from GRACE/GRACE-FO and SMB-D (2003-2018) for the Greenland Ice Sheet, along with regional estimates for 2017-2018 for East and West. Figure 3: Rate of mass change for year 2019 from GRACE/GRACE-FO and SMB-D Figure 5: Annual mass balance and its main components from SMB-D (1948-2019) and GRACE/GRACE-FO (2003-2019)

Description: Here, we provide the raw pollen data archived in three Siberian lake sediment cores spanning the mid-Holocene to the present (7.6-0 cal ka BP), from northern typical tundra to southern open larch forest in the Omoloy region. There are three cores: 1. 14-OM-20B, Lat. / °: 70.53, Lon. / °: 132.91, Ele. / m a.s.l.: 52, Modern vegetation: open larch forest, Lake area / km2: 0.26, Maximal depth / m: 3.4 2. 14-OM-02B, Lat. / °: 70.72, Lon. / °: 132.67, Ele. / m a.s.l.: 58, Modern vegetation: forest tundra, Lake area / km2: 0.08, Maximal depth / m: 3.5 3. 14-OM-12A, Lat. / °: 70.96, Lon. / °: 132.57, Ele. / m a.s.l.: 60, Modern vegetation: tundra, Lake area / km2: 0.09, Maximal depth / m: 4.5 Three lake sediment cores, 14OM12A (33 cm long), 14OM02B (49.5 cm long) and 14OM20B (86 cm long), were recovered from three sites using a UWITEC gravity corer (6 cm internal diameter) equipped with a hammer tool in July 2014. From the three cores, 16 bulk organic carbon samples were selected because of the lack of macrofossil remains and radiocarbon dated using accelerator mass spectrometry (AMS) at Poznań radiocarbon laboratory of Adam Mickiewicz University, Poland. In addition, 30 freeze-dried samples per core at 0.25 or 0.5 cm intervals between 0 and 15 cm were analysed for 210Pb/137Cs at the Liverpool University Environmental Radioactivity Laboratory. In this project, we analyse pollen and sedaDNA (Liu et al., 2020; doi:10.5061/dryad.69p8cz900) from three lake sediment cores from the Omoloy region in north-eastern Siberia (northern Yakutia), which are currently surrounded by different vegetation types ranging from typical tundra to open larch forest. First, our aim is to compare sedaDNA with the pollen data to see whether both methods track the same pattern with respect to compositional changes and diversity changes across the northern Russian treeline zone or are complementary to each other. Second, we reconstruct the mid- to late-Holocene changes of vegetation composition along a north–south transect. Third, we use the sedaDNA data to reconstruct variations in species richness and relate this to vegetation and climate change.

Description: Understanding the resilience of African savannas to global change requires quantitative information on long-term vegetation dynamics. Here we present a reconstruction of past vegetation cover of the northern Namibian savanna obtained after applying the REVEALS model to fossil pollen data from Lake Otjikoto. We also present modern pollen and vegetation data used to calculate pollen productivity estimates for the major Namibian savanna taxa Acacia (Senegalia, Vachellia), Combretaceae, Dichrostachys, Grewia and Poaceae. Data were collected at 10 sites along a rainfall gradient in north central Namibia. Modern pollen was extracted from soil samples collected from plots at the different sites. Vegetation data were extracted from satellite images covering a 1.5 km radius from the plots where pollen was collected. The mean cover of the studied taxa was calculated by 100 m rings.

Description: The Late Holocene is a substantial cultural and economic transition in the eastern Eurasian Steppe and Altai Region, but paleoclimate conditions during this time remain unclear. Therefore, we established a high-resolution paleoclimate record from Lake Khar Nuur in the Mongolian Altai, spanning the last 4200 years. Lake Khar Nuur is a high-altitude lake with a small catchment located at 2,486 m a.s.l. (48°37'22.9"N, 88°56'42.5"E). We recovered the sediment core (that we abbreviate KN18) from the deepest part of the lake (49.4 m) in July 2018 using an Uwitec gravity corer. Within the sediment core KN18, a wide array of lake sediment proxies was measured. While total organic carbon (TOC), total nitrogen, bulk δ^13^C~TOC~, δ^15^N and biogenic silica were measured in 2 cm resolution, the elemental composition (log (Ca/Ti) ratio) was measured in 0.5 cm resolution. Additionally, compound-specific hydrogen isotopic composition of _n_-alkanes was measured in 1 cm resolution.

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: The data set contains the results of laboratory examination of 13 soil samples taken at the ground truthing reference sites during the flight campaign.

Description: Here we present soil characteristics from Alpine European larch and Swiss pine forests, as well as mixed forests. The forests are located in the LTSER area "Val Mazia/Matschertal" in the Vinschgau Valley, South Tyrol, Italy. Each three replicates from each forest type (larch, pine, and mixed) were sampled in late summer 2017.

Description: This dataset includes alkalinity measurements of a loess weathering column experiment, which was conducted under laboratory conditions with atmospheric pCO2.

Description: This dataset includes alkalinity measurements of a loess weathering column experiment, which was conducted under laboratory conditions with saturated pCO2.