ALBERT

Description: Representation of the shelf areas in the global ocean model: key study, questions and perspectives The East Siberian Arctic Shelf (ESAS), consisting of the Laptev, East Siberian and Chukchi Seas, represents the shallowest and broadest shelf region of the entire World Ocean. It occupies a little more than 20% of the total area covered by the Arctic Ocean (AO) and represents a critical physical and biochemical gateway for exchange between AO and terrestrial zone with complex oceanographic and biogeochemical regime influenced by both seawaterof Pacific and Atlantic origins. The is a growing need for better quality estimations of circulation and dynamics on the shelf to answer major present and future scientific, ecosystem and societal issues, because of changing climate. It is a complex task as soon as the ESAS represents wide area with variety of regimes and there is still substantial uncertainty in their role and feedbacks with the wider climate system. Making progress on this is largely dependent on the accurate reproducing of the physical environment in the coupled coastal-open ocean system. We would like to propose modeling system that will help to answer questions on the ESAS observed and future trends and dynamics features across time and space scales tracing the signal through the system Estuaries-ESAS-AO in both upscaling and downscaling directions. To reach mentioned goals, we built a coastal branch of the finite volume version of the global sea ice-ocean model FESOM (Danilov et al., 2004; Danilov, 2012; Wang et al., 2014). FESOM is the first model worldwide that provides multi-resolution functionality to large-scale ocean modeling, allowing to bridge the gap between scales. This unique feature is crucial for high efficient coupling, as soon as the exchange zone can be resolved similarly (with the same resolution) by the global and local solutions. Additional strong side of the elaboration of the coastal branch for the existing global model is a possibility to organize flux treatment in a same manner, increasing efficiency of coupling. Danilov, S., Kivman, G., Schröter, J. (2004). A finite-element ocean model: principles and evaluation, Ocean Model., 6, 125–150. Danilov, S. (2012). Two finite-volume unstructured mesh models for large-scale ocean modeling. Ocean Modell., 47, 14–25. Wang, Q., Danilov, S., Sidorenko, D., Timmermann, R., Wekerle, C., Wang, X., Jung, T., and Schröter, J. (2014). The Finite Element Sea Ice-Ocean Model (FESOM) v.1.4: formulation of an ocean general circulation model, Geosci. Model Dev., 7, 663–693.

Description: The Lena River (Lena R.) heat flux affects the Laptev Sea hydrology. Published long-term estimates range from 14.0 to 15.7 EJ·a−1, based on data from Kyusyur, at the river outlet. A novel daily stream temperature (Tw) dataset was used to evaluate contemporary Lena R. heat flux, which is 16.4 ± 2.7 EJ·a−1 (2002–2011), confirming upward trends in both Tw and water runoff. Our field data from Kyusyur, however, reveal a significant negative bias, −0.8 °C in our observations, in observed Tw values from Kyusyur compared to the cross-section average Tw. Minor Lena R. tributaries discharge colder water during July–September, forming a cold jet affecting Kyusyur Tw data. Major Tw negative peaks mostly coincide with flood peaks on the Yeremeyka River, one of these tributaries. This negative bias was accounted for in our reassessment. Revised contemporary Lena R. heat flux is 17.6 ± 2.8 EJ·a−1 (2002–2011) and is constrained from above at 26.9 EJ·a−1 using data from Zhigansk, approximately 500 km upstream Kyusyur. Heat flux is controlled by stream temperature in June, during the freshet period, while from late July to mid-September, water runoff is a dominant factor.

Description: Rapid frontline retreat and melting of tidewater glaciers along the Antarctic Peninsula cause surface erosion resulting in a washout of suspended particulate matter (SPM) into coastal surface waters. In Potter Cove, a fjord of ~8.5 km2 surface area, meltwater streams transport 23000-39000 tons of eroded sediments per year that disperse into a five meter thick surface layer varying in spatial expansion depending on wind direction and tidal circulation. We addressed the spatial dynamics of the sediment plume in Potter Cove by modelling SPM circulation under different hydrographic scenarios. We applied numerical implementation of the three-dimensional unstructured-mesh model FESOM-C intended for coastal simulations (1). This model is equipped with the high order horizontal advection schemes and rich variety of the vertical turbulence closures based on implemented GOTM turbulence module (2). The model is based on a finite-volume cell-vertex discretization and works on hybrid unstructured meshes composed of triangles and quads. Model performance was validated by available observations. Our results reveal that water transportation due to lower velocity values close to the glacier front; retain the SPM inside the cove, so that this inner-cove area is more strongly impacted by sedimentation.

Description: The East Siberian Arctic Shelf (ESAS), consisting of the Laptev, East Siberian and Chukchi Seas, represents the world’s shallowest and broadest shelf region stretching more than 2500 km long, with an average depth of about 30−40 m and extending up to 800 km from the shoreline. It occupies a little more than 20% of the total area covered by the Arctic Ocean (AO) and represents a critical physical, biogeochemical and ecological gateway for exchange between the AO and the terrestrial environment. Its complex oceanographic and biogeochemical regime is influenced by both seawater of Pacific and Atlantic origins. The importance and role of the ESAS in the rapidly changing Arctic climate system, environment and economic activities can hardly be overstated. Because of changing climate, there is an increasing urgency and growing need for better quality measurements and models of circulation and dynamics on the shelf to answer major present and future scientific, ecosystem and societal issues. We must underline the importance of the ESAS investigation and necessity to consider this area in conjunction with the AO and Arctic Coast. It is a complex task as soon as the ESAS represents a large area with a wide border with AO and variety of regimes and there is still substantial uncertainty in their role and feedbacks with the wider climate system. In this sense numerical simulations are a powerful instrument. Making progress on this largely depends on the accurate representation of the physical environment in a coupled coastal-open ocean system. In its turn an accurate model representation of the physical processes is a pre-request for plausible simulation of the biogeochemical cycles and ecosystem dynamics. However, studying of the coupled system still represents a great scientific challenge. For this reason the majority of scientific research has been mainly studying the communication and responses within smaller subsets of the ESAS-open ocean system. The main goal of the project is to answer questions on the ESAS observed and future trends and dynamic features across time and space scales, tracing water masses, sea ice, biogeochemical and ecological signals from the Estuaries/coastal zone to the AO/Global Ocean through the ESAS in both upscaling and downscaling directions. To reach mention goal we will develop a multi-scale modeling platform and apply it on the background of an extensive base of natural observations and knowledge about the terrestrial impact to the ESAS. The platform will bring understanding of the multi-scale processes confluence under the climate change pressure to a new level. It will represent a virtual lab, where different scenarios about changes on the shelf dynamics can be consistently addressed to a larger scale and vice versa. The platform will constitute an essential foundation for any coastal/shelf region studies in need of accurately accounting for the global signal, and for global studies to trace the fate of high quality coastal signal.​ Proposed modelling platform can support the study dedicated to climate adaptation and mitigation in coastal zones. Its application to the ESAS area has large social and economical weight, in particular it can be used for: Effective sea ice predictions; Ship navigation; Tracing pollution; Forecasting of natural hazards; Fisheries management.