A5064690280- Arctic and Antarctic ice dynamics
- Cryospheric studies and observations
- Climate change and permafrost
- Methane Hydrates and Related Phenomena
- Geology and Paleoclimatology Research
- Climate variability and models
- Oceanographic and Atmospheric Processes
- Ocean Waves and Remote Sensing
- Arctic and Russian Policy Studies
- Icing and De-icing Technologies
- Climate Change Policy and Economics
- Winter Sports Injuries and Performance
- Species Distribution and Climate Change
- Global Energy and Sustainability Research
- Marine animal studies overview
- Isotope Analysis in Ecology
- Geological Studies and Exploration
- Underwater Acoustics Research
- Ultrasonics and Acoustic Wave Propagation
- Smart Materials for Construction
- Geochemistry and Geologic Mapping
- Ocean Acidification Effects and Responses
- Meteorological Phenomena and Simulations
- Hydrocarbon exploration and reservoir analysis
Centre for Polar Observation and Modelling
2019-2024
University College London
2019-2024
University of Manitoba
2023-2024
Centre for Arctic Gas Hydrate, Environment and Climate
2024
UiT The Arctic University of Norway
2023-2024
University of Bristol
2023
Environment and Climate Change Canada
2023
Qingdao National Laboratory for Marine Science and Technology
2022
Arctic Ocean properties and processes are highly relevant to the regional global coupled climate system, yet still scarcely observed, especially in winter. Team OCEAN conducted a full year of physical oceanography observations as part Multidisciplinary drifting Observatory for Study Climate (MOSAiC), drift with sea ice from October 2019 September 2020. An international team designed implemented program characterize system unprecedented detail, seafloor air-sea ice-ocean interface,...
Abstract Sea ice thickness is a critical variable, both as climate indicator and for forecasting sea conditions on seasonal longer time scales. The lack of snow depth density information major source uncertainty in current retrievals from laser radar altimetry. In response to this data gap, new Lagrangian evolution model (SnowModel‐LG) was developed simulate depth, density, grain size pan‐Arctic scale, daily August 1980 through July 2018. study, we evaluate the results effort against various...
Abstract. Mean sea ice thickness is a sensitive indicator of Arctic climate change and in long-term decline despite significant interannual variability. Current estimations from satellite radar altimeters employ snow climatology for converting range measurements to thickness, but this introduces unrealistically low variability trends. When the period 2002–2018 calculated using new data with more realistic trends, we find mean four seven marginal seas be declining between 60 %–100 % faster...
Abstract Satellite observations of sea ice freeboard are integral to the estimation thickness. It is commonly assumed that radar pulses from satellite‐mounted Ku‐band altimeters penetrate through snow and reflect snow‐ice interface. We would therefore expect a negative correlation between accumulation measurements, as increased loading weighs floe down. In this study we produce daily resolution products CryoSat‐2 Sentinel‐3 via recently developed optimal interpolation scheme. find...
Abstract. Pan-Arctic sea ice thickness has been monitored over recent decades by satellite radar altimeters such as CryoSat-2, which emits Ku-band waves that are assumed in publicly available products to penetrate overlying snow and scatter from the ice–snow interface. Here we examine two expressions for time delay caused slower wave propagation through layer related assumptions concerning evolution of density. Two conventional treatments introduce systematic underestimates up 15 cm into...
Abstract The volume of Arctic sea ice is in decline but exhibits high interannual variability, which driven primarily by atmospheric circulation. Through analysis satellite-derived products and reanalysis data, we show that winter 2020/21 was characterised anomalously sea-level pressure over the central Ocean, resulted unprecedented anticyclonic winds ice. This circulation pattern drove older from Ocean into lower-latitude Beaufort Sea, where it more vulnerable to melting coming warm season....
Abstract. Wind-driven redistribution of snow on sea ice alters its topography and microstructure, yet the impact these processes radar signatures is poorly understood. Here, we examine effects over Arctic waveforms backscatter obtained from a surface-based, fully polarimetric Ka- Ku-band at incidence angles between 0∘ (nadir) 50∘. Two wind events in November 2019 during Multidisciplinary drifting Observatory for Study Climate (MOSAiC) expedition are evaluated. During both events, changes...
Abstract. To improve our understanding of how snow properties influence sea ice thickness retrievals from presently operational and upcoming satellite radar altimeter missions, as well to investigate the potential for combining dual frequencies simultaneously map depth thickness, a new, surface-based, fully polarimetric Ku- Ka-band (KuKa radar) was built deployed during 2019–2020 year-long MOSAiC international Arctic drift expedition. This instrument, operate both an (stare mode)...
Abstract. Arctic rain on snow (ROS) deposits liquid water onto existing snowpacks. Upon refreezing, this can form icy crusts at the surface or within snowpack. By altering radar backscatter and microwave emissivity, ROS over sea ice influence accuracy of variables retrieved from satellite altimetry, scatterometers, passive radiometers. During Ocean MOSAiC (Multidisciplinary drifting Observatory for Study Climate) expedition, there was an unprecedented opportunity to observe a event using in...
Abstract The North Atlantic subpolar gyre (SPG) connects tropical and high‐latitude waters, playing a leading role in deep‐water formation, propagation of water into the Arctic, as habitat for many ecosystems. Instrumental records spanning recent decades document significant decadal variability SPG circulation, with associated hydrographic ecological changes. Emerging longer‐term provide circumstantial evidence that also experienced centennial trends during 20th century. Here, we use marine...
Abstract The volume, extent and age of Arctic sea ice is in decline, yet winter production appears to have been increasing, despite warming being most intense during winter. Previous work suggests that further will at some point lead a decline production, however consistent explanation both rise fall hitherto missing. Here, we investigate these driving factors through simple linear model for production. We focus on the Kara Laptev seas-sometimes referred as “ice factories” their outsized...
Abstract As Arctic sea ice and its overlying snow cover thin, more light penetrates into the upper ocean, shifting phenology of algal growth within bottom ice, with cascading impacts on higher trophic levels marine ecosystem. While field data or autonomous observatories provide direct measurements coupled ice‐algal system, they are limited in space time. Satellite observations key variables that control amount penetrating through offer possibility to map under‐ice across entire basin. This...
Abstract Hudson Bay has warmed over 1 °C in the last 30 years. Coincident with this warming, seasonal patterns have shifted, spring sea ice melting earlier and fall freeze-up occurring later, leading to a month longer of ice-free conditions. This extended period presents significant challenge for polar bears, as it restricts their hunting opportunities seals ability accumulate necessary body weight successful reproduction. Drawing on latest insights from CMIP6, our updated projections...
Surface-based Ku-band radar altimetry investigations indicate the signal is typically backscattered from well above snow-sea ice interface. However, this would induce a bias in satellite altimeter sea thickness retrievals not reflected by buoy validation. Our study presents mechanism to potentially explain paradox: probabilistic quasi-specular scattering snow-ice We introduce theory for before identifying it airborne observations collected over landfast first year Arctic near Eureka, Canada,...
Abstract Snow depth on sea ice is an Essential Climate Variable and a major source of uncertainty in satellite altimetry‐derived thickness. During winter the MOSAiC Expedition, “KuKa” dual‐frequency, fully polarized Ku‐ Ka‐band radar was deployed “stare” nadir‐looking mode to investigate possibility combining these two frequencies retrieve snow depth. Three approaches were investigated: dual‐polarization waveform shape, compared independent measurements. Novel yielded r 2 values up 0.77....
The Arctic winter-time atmospheric boundary layer often features strong and persistent low-level stability which arises from longwave radiative cooling of the surface during polar night. This stable stratification results in a positive lapse rate feedback, is major contributor to amplification. A second state, associated with cloudy conditions, weaker near-zero net flux also observed. Previous work has shown that many CMIP5 climate models fail realistically represent state. In this study, we...
Abstract Satellite radar altimeters like CryoSat‐2 estimate sea ice thickness by measuring the return‐time of transmitted pulses, reflected from and ocean surface, to measure freeboard. Converting freeboard requires an assumption regarding fractional depth snowpack which waves backscatter . We derive data with incremental values for , 2010–2021 winter periods. By comparing these estimates derived upward‐looking sonar moorings, we find that between 35%–80% result in best representation...
Abstract. Arctic rain-on-snow (ROS) deposits liquid water onto existing snowpacks. Upon refreezing, this can form icy crusts at the surface or within snowpack. By altering radar backscatter and microwave emissivity, ROS over sea ice influence accuracy of variables retrieved from satellite altimetry, scatterometers, passive radiometers. During Ocean MOSAiC Expedition, there was an unprecedented opportunity to observe a event using in situ active instruments similar those deployed on...
Abstract Salt is often present in the snow overlying seasonal sea ice, and has profound thermodynamic electromagnetic effects. However, its provenance behaviour within remain uncertain. We describe two investigations tracing upward brine movement snow: one conducted laboratory field. The experiments involved addition of dyed to base terrestrial samples, with subsequent wicking being measured. Our field experiment dye added directly (without brine) bare sea-ice lake ice surfaces, then...
Abstract. Pan-Arctic sea ice thickness has been monitored over recent decades by satellite radar altimeters such as CryoSat-2, which emit Ku-band waves that are conventionally assumed to penetrate overlying snow and scatter from the ice-snow interface. Here we examine two expressions for time delay caused slower wave propagation through layer related assumptions concerning time-evolution of density. Two conventional treatments lead systematic underestimates winter thermodynamic growth rate...
Abstract. To improve our understanding of how snow properties influence sea ice thickness retrievals from presently operational and upcoming satellite radar altimeter missions, as well investigating the potential for combining dual frequencies to simultaneously map depth thickness, a new, surface-based, fully-polarimetric Ku- Ka-band (KuKa radar) was built deployed during 2019–2020 year-long MOSAiC International Arctic drift expedition. This instrument, operate both an (stare mode)...
Abstract. Wind transport alters the snow topography and microstructure on sea ice through redistribution controlled by deposition erosion. The impact of these processes radar signatures is poorly understood. Here, we examine effects Arctic from Ka- Ku-band signatures. Measurements were obtained during two wind events in November 2019 MOSAiC expedition. During both events, changes waveforms backscatter coincident with surface height measured a terrestrial laser scanner are observed. At...
Abstract. The Arctic is warming at almost 4 times the global average rate. Here we reframe this amplified in terms of climate ambition to show that without amplification, world would breach Paris Agreement's 1.5 and 2 ∘C limits 5 8 years later, respectively. We also find be a disproportionate contributor uncertainty timing breaches. outsized influence on targets highlights need for better modelling monitoring change.