ALBERT

Description: This data set includes spatial high-resolution bathymetry data sets for the Lena Delta and Kolyma Gulf regions. Based on large-scale current and historical nautical maps, depth points and isobaths lines were manually digitized and served as input data for the bathymetry models. The models were calculated with the topo to raster tool in ArcGIS TM version 10.6 into a 50 m (TTR50) and a 200 m (TTR200) grid cell bathymetry for both regions. The models were validated with depth data derived from ship cruises in 2019 (Fuchs et al., submitted, Palmtag et al., 2021, Palmtag and Mann, 2021) and water depth data available on PANGAEA (e.g. Hölemann et al., 2020). Beside the bathymetry models for the Lena Delta and Kolyma Gulf regions which are available in GeoTiff format, this data set contains the complete input data for the models, which includes the depth point data, the isobaths lines, and the water area extent in shapefile format for both regions.

Description: This data set includes the 50 m and 200 m bathymetry model for the Lena Delta region covering 232,700 km2 stretching from Cape Mamontov Klyk in the western Laptev Sea to Kotelny Island in the New Siberian Islands. The models were calculated with the topo to raster tool in ArcGIS TM version 10.6 based on depth points and isobaths lines derived from large-scale current and historical nautical maps. The final bathymetry models are available in GeoTiff format in 50 m (TTR_50m_LenaDelta.tif) and 200 m (TTR_200m_LenaDelta.tif) spatial resolution. In addition, the data set includes the complete input data for the bathymetry models. The input data consists of a point shapefile (Depth_points_LenaDelta.shp) including 50,828 manually digitized depth point measurements, a polyline shapefile (Isobaths_LenaDelta.shp) including 720 manually digitized isobath lines and a polygon shapefile (Water_area_LenaDelta.shp) for the water extent. The Lena Delta region bathymetry was validated with depth data derived from ship cruises in 2019 (Fuchs et al. submitted, Palmtag et al., 2021) as well as water depth data available on PANGAEA (e.g. Hölemann et al., 2020).

Description: This data set includes the 50 m and 200 m bathymetry model for the Kolyma Gulf region covering an area of 12,100 km2 extending from the apex of the Kolyma Delta (5 km downstream of the city of Cherskiy) to 70 km offshore into the East Siberian Sea. The models were calculated with the topo to raster tool in ArcGIS TM version 10.6 based on depth points and isobaths lines derived from large-scale current and historical nautical maps. In addition, the water area extent for this region was derived from the Global Surface Water layer by Pekel et al. (2016). The final bathymetry models are available in GeoTiff format in 50 m (TTR_50m_KolymaGulf.tif) and 200 m (TTR_200m_KolymaGulf.tif) spatial resolution. In addition, the data set includes the complete input data for the bathymetry models. The input data consists of a point shapefile (Depth_points_KolymaGulf.shp) including 24,126 manually digitized point depth measurements, a polyline shapefile (Isobaths_KolymaGulf.shp) including 1,053 manually digitized isobath lines and a polygon shapefile (Water_area_KolymaGulf.shp) for the water extent. The Kolyma Gulf region bathymetry was validated with depth data derived from ship cruises in 2019 (Palmtag and Mann, 2021).

Description: Massive Arctic rivers are feeding ≈11% of the global river discharge into the Arctic Ocean, while the ocean stores only ≈1% of the global ocean volume. The ongoing rapid climate warming has led to pronounced changes in precipitation, active layer thickening, increased air and soil temperatures, increased riverbank and coastal erosion rates, extensive permafrost thaw and increasing freshwater discharge to the Arctic Ocean. Since most studies have focused on rivers or oceans itself and mainly during the late summer, near-shore coastal regions are understudied and crucial in determining the amount of carbon transported and/or released into the Arctic Ocean. Here, we investigated river-derived carbon dioxide (CO2) and methane (CH4) emissions from seven repeated transects of the Kolyma River and nearshore (120 km between Cherskiy and Ambarchik) over the entire open water season between June and September 2019. We estimated the cumulative gross delivery of river-derived CH4 and CO2 to the coastal ocean to be around 0.0008 Tg CH4 (800 000 kg) and 0.2 Tg CO2 (200 000 000 kg). Measurements reveal that more than 50% of the cumulative gross delivery is happening during the fresh period, making the season dynamics extremely important.

Description: The Arctic ocean receives 11% of the global river discharge and the Arctic rivers drain large permafrost rich catchments. Where these rivers outflow into the marginal shelf seas of the Arctic ocean the terrestrial dissolved organic matter (tDOM) which they transport has an important role to play in the coastal ecosystem. This tDom is derived from inland permafrost and as it thaws under future climate scenarios there are expected to be changes to both the composition and quantity of riverine tDOM. At the same time there will be changes to the seasonality and magnitude of river discharge, due to increased precipitation and earlier snow melt, and to the light availability, due to reduced seasonal sea ice. To understand the possible impact of these changes on the coastal ecosystem it is important to understand the present role of permafrost derived tDOM and the possible changes to the nearshore circulation. We model the hydrodynamics of the extensive shallow shelf of the Laptev sea, into which drains the Lena river – the 13th largest in the world by discharge. The output from the hydrodynamic model is used to drive the ecosystem model ERSEM which has been adapted to explicitly include a permafrost tDOM input. This coupled model system allows us to investigate both the role of present day tDOM in an Arctic coastal ecosystem and to hypothesise on the impact of increases in future. In particular we attempt to quantify the efficacy of the microbial carbon pump under different tDOM inputs.

Description: No other region has warmed as rapidly in the past decades as the Arctic. Funded by the British Natural Environment Research Council (NERC) and the German Federal Ministry of Education and Research (BMBF), the Changing Arctic Carbon cycle in the Coastal Ocean Near-shore (CACOON) project investigates how this warming influences Arctic coastal-marine ecosystems. Arctic rivers annually carry around 13% of the globally transported dissolved organic carbon (despite the Arctic Ocean making up only approx. 1% of the Earth's ocean volume). Arctic shelf waters are therefore dominated by terrestrial organic carbon pools, so that shelf ecosystems are intimately linked to freshwater supplies. Arctic ecosystems also contain permafrost organic carbon that may be released with warming. Climate change already thaws permafrost, reduces sea ice and increases riverine discharge, triggering important feedbacks. The importance of the near-shore region, consisting of several tightly connected ecosystems that include rivers, deltas, and the shelf, is however often overlooked. Year-round studies are scarce but needed to predict the impact of shifting seasonality, fresher water, changing nutrient supply and greater proportions of permafrost-derived organic carbon on coastal waters. The aims of the CACOON project are to quantify the effect of changing freshwater export and permafrost thaw on the type and fate of river-borne organic matter (OM) delivered to the Arctic shore and resulting changes on ecosystem functioning in the coastal Arctic Ocean. We are achieving this through a combined observational, experimental, and modelling approach. We conduct laboratory experiments to parameterise the susceptibility of terrigenous organic carbon to abiotic and biotic transformation and losses, then use the results from these to deliver a marine ecosystem model capable of representing major biogeochemical cycles. We apply this model to assess how future changes to freshwater runoff and carbon fluxes alter the ecosystems. To reach these aims, we conducted 4 field campaigns in 2019 in the Lena (see https://epic.awi.de/id/eprint/53575/) and Kolyma Delta region. In the Lena Delta, during spring we were using a mobile camp on sledges to collect water samples, ice cores, surface sediments, gas samples as well as CTD profiles. A permafrost cliff (Sobo-Sise) was sampled to analyse terrestrial endmembers of organic matter entering the deltaic and eventually marine system following erosion and transport. During the summer campaign we retrieved samples along a 200 km transect from the centre of the Delta to the Laptev Sea covering the fresh-salt water transition. The aim of Kolyma field sampling was to capture the open water season from the ice breakup to re-freezing and sample the Kolyma River and the near shore area. The lab work on these samples is currently ongoing with first papers lead by CACOON or with project contributions being published already (available here: https://www.researchgate.net/project/CACOON-Changing-Arctic-Carbon-cycle-in-the-coastal-ocean-near-shore).

Description: No other region has warmed as much or as rapidly in the past decades as the Arctic. A new project, CACOON, will investigate how the ecosystems are influenced by this warming. Funded by the British Natural Environment Research Council (NERC) and the German Federal Ministry of Education and Research (BMBF), CACOON will also help to better predict changes to the Arctic coastal-marine environment. Arctic rivers annually carry around 13% of all dissolved organic carbon transported globally from land to ocean, despite the Arctic Ocean making up only approximately 1% of the Earth’s ocean volume. Arctic shelf waters are therefore dominated by terrestrial carbon pools, so that shelf ecosystems are intimately linked to freshwater supplies. Arctic ecosystems also contain perennially frozen carbon that may be released by further warming. Climate change already thaws permafrost, reduces sea-ice and increases riverine discharge over much of the pan-Arctic, triggering important feedbacks. The importance of the near-shore region, consisting of several tightly connected ecosystems that include rivers, deltas, estuaries and the continental shelf, is however often overlooked. We need year-round studies to be able to predict the impact of shifting seasonality, fresher water, changing nutrient supply and greater proportions of permafrost-derived carbon on coastal waters CACOON addresses this knowledge gap by investigating the near-shore regions of the two major Arctic rivers, the Lena and Kolyma, which together drain 19% of the pan-Arctic watershed area. CACOON will quantify the effect of changing freshwater export and terrestrial permafrost thaw on the type and fate of river-borne organic matter delivered to Arctic coastal waters, and the resultant changes to ecosystem functioning in the coastal Arctic Ocean. We will achieve this though a combined observational, experimental and modelling study. We will conduct laboratory experiments to parameterize the susceptibility of terrigenous carbon to abiotic and biotic transformation and losses, then use the results from these to deliver a marine ecosystem model of the major biogeochemical cycles of carbon, nutrients and organic matter cycling in these regions.

Description: No other region has warmed as much or as rapidly in the past decades as the Arctic. A new project, CACOON, investigates how the ecosystems are influenced by this warming. Funded by the British Natural Environment Research Council (NERC) and the German Federal Ministry of Education and Research (BMBF), CACOON will help to better predict changes to the Arctic coastal-marine environment. Arctic rivers (Fig. 1) annually carry around 13% of all dissolved organic carbon transported globally from land to ocean, despite the Arctic Ocean making up only approximately 1% of the Earth's ocean volume. Arctic shelf waters are therefore dominated by terrestrial carbon pools, so that shelf ecosystems are intimately linked to freshwater supplies. Arctic ecosystems also contain perennially frozen carbon that may be released by further warming. Climate change already thaws permafrost, reduces sea-ice and increases riverine discharge over much of the pan-Arctic, triggering important feedbacks (Mann et al. 2015). The importance of the near-shore region, consisting of several tightly connected ecosystems that include rivers, deltas, estuaries and the continental shelf, is however often overlooked. We need year-round studies to be able to predict the impact of shifting seasonality, fresher water, changing nutrient supply and greater proportions of permafrost-derived carbon on coastal waters

Description: The Laptev sea in the Russian Arctic receives organic rich sediments from both erosion of coastal cliffs and from the Lena river, the worlds 13th largest by discharge, which drains a large permafrost rich area of the Asian continent. These sediments differ both in their physical characteristics and in the bioavailability of their carbon. The comparative distribution and residence time of these two sediment types will therefore have an impact on the shelf biogeochemistry. We use the unstructured grid hydrodynamic model FVCOM to model the Laptev sea around the Lena outflow. Output from this model drives a simple model of sediment tracers, with seperate classes for coastal and riverine input. Existing sediment observations are used to calibrate the model setup. This setup is used to study the spatial distribution and residence times of the two sediment sources both under current conditions and under a future scenario reflecting the expected change in freshwater input and ice cover.