Quantitative assessment of two oil-in-ice surface drift algorithms

The ongoing reduction in extent and thickness of sea ice in the Arctic might result in an increase of oil spill risk due to the expansion of shipping activity and oil exploration shift towards higher latitudes. This work assessed the response of two oil-in-ice surface drift models implemented in an open-source Lagrangian framework. By considering two numerical modeling experiments, our main finding indicates that the drift models provide fairly similar outputs when forced by the same input. It was also found that using higher resolution ice-ocean model does not imply better results. We highlight the role of sea ice in the spread, direction and distance traveled by the oil. The skill metric seems to be sensitive to the drift location, and drift model re-initialization is required to avoid forecast deterioration and ensure the accurate tracking of oil slicks in real operations.publishedVersio

Marine Plastic Drift from the Mekong River to Southeast Asia

Southeast Asia is the world’s most polluted area in terms of marine plastics. The Mekong River is one of the largest rivers in the area, and ranked as somewhere between the 8th- and 11th-biggest contributor to plastics in the world’s oceans. Here, we investigate how microplastics drift from the Mekong river to Southeast Asia, and which coastlines are most exposed. We identify potential factors (wind drift, rivers, vertical mixing and sinking rates) that affect plastic drift in the region using the OpenDrift model with realistic wind and ocean currents for simulations between three months (summer and winter) and 15 months. We find that the seasonal drift is influenced by the monsoon systems and that most of the plastics strand in the Philippines and Indonesia. In addition, the role of wind drift is significant in strong winds. Vertical mixing and sinking rates are unknowns that affect the relative importance of wind drift (near the surface) and ocean currents. Simulations with different terminal velocities show that, unsurprisingly, the higher the terminal velocities are, the closer they deposit to the source. In light of the large uncertainties in sinking rates, we find that the plastic distribution has large uncertainties, but is clearly seasonal and influenced by wind, vertical mixing, river discharge and sinking rates. The Philippines and Indonesia are found to have the coastlines that are most exposed to plastic pollution from the Mekong river. This study shows that simulations of marine plastic drift are very variable, depending on many factors and assumptions. However, it provides more detailed information on marine plastic pollution in Southeast Asia, and hopefully helps authorities take more practical actions.publishedVersio

Estimating a mean transport velocity in the marginal ice zone using ice-ocean prediction systems

Understanding the transport of objects and material in the marginal ice zone (MIZ) is critical for human operations in polar regions. This can be the transport of pollutants, such as spilled oil, or the transport of objects, such as drifting ships and search and rescue operations. For emergency response, the use of environmental prediction systems are required which predict ice and ocean parameters and are run operationally by many centres in the world. As these prediction systems predict both ice and ocean velocities, as well as ice concentration, it must be chosen how to combine these data to best predict the mean transport velocities. In this paper we present a case study of four drifting buoys in the MIZ deployed at four distinct ice concentrations. We compare short-term trajectories, i.e. up to 48 h lead times, with standard transport models using ice and ocean velocities from two operational prediction systems. A new transport model for the MIZ is developed with two key features aimed to help mitigate uncertainties in ice–ocean prediction systems: first, including both ice and ocean velocities and linearly weighting them by ice concentration, and second, allowing for a non-zero leeway to be added to the ice velocity component. This new transport model is found to reduce the error by a factor of 2 to 3 for drifters furthest in the MIZ using ice-based transport models in trajectory location after 48 h.publishedVersio

Current shear and turbulence during a near-inertial wave

Surface currents and turbulent mixing were observed during a near-inertial wave (NIW) using an accousting doppler current profiler (ADCP) and satellite-tracked drifters. Drifter trajectories sampled at three depth levels show characteristics of an Ekman solution superposed with the NIW. Velocity and dissipation estimates from the ADCP reveal strong shear with a distinct constant flux layer in between the roughness length and a critical depth at 4m. Below, a shear free slab layer performing an inertial oscillation is observed. Dissipation, as estimated from the vertical beam of the ADCP, peaks in the wave-enhanced friction layer when the current opposes the wind and wave direction. Below the constant flux layer, maximum turbulence is observed when the NIW is in a phase that is in opposite direction to the time-averaged current. During this phase, currents at various depths rapidly realign in the entire boundary layer.publishedVersio

Impacts of offshore oil spill accidents on island bird communities: A test run study around Orkney and Svalbard archipelagos

The sea area around the Orkney archipelago, Scotland is subjected to substantial maritime shipping activities. By contract, the Svalbard archipelago, Norway currently has a rather low marine traffic profile. Future projections, however, indicate that the Trans-Arctic route might change the whole transportation picture and Svalbard may be at the centre of maritime activities. Both archipelagos have sensitive environmental resources at sea and inland, including bird communities. There are, for instance, 13 Red Listed species present in Orkney and 2 in Svalbard. In this regard, it is important to address oil spill risks along existing and projected shipping routes. Hypothetical spills were simulated in twelve scenarios for both the Orkney and Svalbard archipelagos with the OpenDrift open-source software. The results indicate risks to seabird communities. For Orkney, the spills resulted in the most extensive contamination of the sea and land environments in autumn. For Svalbard, autumn spills on the contrary presented the lowest risk to seabirds. Based on the simulations, we recommend increased caution for shipping activities in the problematic seasons, improved local readiness for ship accidents and sufficient preincident planning

Long term simulations of potential oil spills around Cuba

Simulations over eight years of continuous surface oil spills around Cuba are carried out to identify the most likely stranding (beaching) locations. The open source Lagrangian oil drift model OpenOil is applied with high resolution hydrodynamic forcing. The actual fraction of the released oil mass reaching different regions is calculated, revealing small differences between a light and a heavy crude oil type. Similar stranding rates for the two oil types are found. Another important conclusion is that, due to the high temporal variability in stranding rates, short term simulations of a few weeks are not suitable to assess environmental risk. The highest stranding rates are simulated in winter in Northern Cuba. It is also found that oil could reach Northern Cuba, Yucatan or Florida in about 3–5 days after a spill.publishedVersio

Risk assessment of the predatory mite Stratiolaelaps scimitus for biological control of varroa mites in beehives : Scientific opinion of the panel on plant health of the Norwegian scientific committee for food and environment

Source at https://vkm.no/.publishedVersio

Assessment of possible adverse consequences for biodiversity when planting vascular plants outside their natural range in Norway - Scientific Opinion of the Panel on Alien Organisms and Trade in Endangered species (CITES) of the Norwegian Scientific Committee for Food and Environment (VKM)

We sow or plant vascular plant species on a large scale in revegetation and restoration projects in Norway today. Some of the species used are already found in Norway, but many of the species, subspecies or populations used though native are not local, that is, they are regionally alien. A regionally alien species is a species that is native to Norway (has been in Norway since 1800) somewhere in the country, but which has been spread by humans to places in Norway where they do not occur. In theory, and according to the Biodiversity Act, it is desirable to use local seeds or plants to preserve local biodiversity. The aim of this report is to define guidelines that helps prevent the planting of vascular plant species with a high potential for negative effects on local biodiversity. It is assumed that the native or local populations are better adapted to local environmental conditions than populations from other areas or regions, and the risk of harmful genetic changes is therefore considered small when using local plant and seed sources. Arriving at a common definition for the area within which plants are “local” is difficult, though; vascular plant species are numerous (3317 species in mainland Norway, of which more than half are alien species introduced after 1800, Artdatabanken 2015), have different growth forms, different environmental requirements, and different reproductive and dispersal ecology. Even closely related vascular plant species can differ in such characteristics and hence in the extent of the "place" or “area”. The dispersal ecology of a plant species is of great importance for whether the species has genetically distinct populations within its range or not. Different strategies (wind pollination vs. insect pollination, vegetative propagation vs. seed dispersal, large seeds vs. small seeds) have an impact on the degree of gene flow between populations and thus also how locally adapted the species is in different areas. Whether the species has primarily vegetative reproduction or whether it spreads mainly by means of seeds, and whether the seed dispersal takes place ballistically, with wind or water, or by zookori (attached to animals or eaten by animals) determines how far the species can spread and how large gene flow there is between different populations. Whether the species is pollinated by wind or by the help of insects also affects the degree of gene flow differently. In Norway, there is great variation in many biophysical and ecological conditions (climate, topography, hydrology, and geology) over relatively short distances. This means that species that grow only a few meters apart can grow under different environmental conditions. This large variation in environmental conditions - on different spatial scales - can give rise to local genetic adaptation. However, plants have been moved around the landscape for several hundred years by our livestock (as seeds in fur and hooves, and in faeces) from lowland pasture to mountain pasture and along traffic arteries across the country due to the extensive transport of animals and people. Over time, this has led to expanded geographical distribution for several species and increased gene flow between populations over relatively large distances. .............publishedVersionpublishedVersio

Assessment of risk and risk-reducing measures related to the introduction and dispersal of the invasive alien carpet tunicate Didemnum vexillum in Norway

Didemnum vexillum is colonial sea squirt, a marine species which originates from the northwest Pacific; it was first recorded in Norway in November 2020. Didemnum vexillum is an alien species, meaning that it is a species that has been transferred from its original region to other regions of the world through human activity, and it had not previously been recorded in Norwegian waters. The species is regarded as having great invasive potential and having strong negative ecological effects on biodiversity. It is also considered to pose a risk to marine industries such as shipping and aquaculture, with possible major negative economic impacts.Assessment of risk and risk-reducing measures related to the introduction and dispersal of the invasive alien carpet tunicate Didemnum vexillum in NorwaypublishedVersio