A5014816071- Arctic and Antarctic ice dynamics
- Cryospheric studies and observations
- Climate change and permafrost
- Methane Hydrates and Related Phenomena
- Soil Moisture and Remote Sensing
- Scientific Research and Discoveries
- Marine and environmental studies
- Spacecraft and Cryogenic Technologies
- Marine and fisheries research
- Calibration and Measurement Techniques
- Atmospheric and Environmental Gas Dynamics
- Marine animal studies overview
- Icing and De-icing Technologies
- Atmospheric aerosols and clouds
- Marine and Coastal Research
- Oceanographic and Atmospheric Processes
- Infrared Target Detection Methodologies
- Underwater Acoustics Research
- Radiation Detection and Scintillator Technologies
- Winter Sports Injuries and Performance
- Spacecraft Design and Technology
- Nuclear Physics and Applications
- Gold and Silver Nanoparticles Synthesis and Applications
- Climate variability and models
- Ultrasonics and Acoustic Wave Propagation
University of Bremen
2015-2024
Technical University of Denmark
2021-2023
Institut de Ciències del Mar
2023
University of Manitoba
2021
Finnish Meteorological Institute
2021
Universität Hamburg
2021
Norwegian Meteorological Institute
2021
Danish Meteorological Institute
2021
Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung
2015-2020
Year-round observations of the physical snow and ice properties processes that govern pack evolution its interaction with atmosphere ocean were conducted during Multidisciplinary drifting Observatory for Study Arctic Climate (MOSAiC) expedition research vessel Polarstern in Ocean from October 2019 to September 2020. This work was embedded into interdisciplinary design 5 MOSAiC teams, studying atmosphere, sea ice, ocean, ecosystem, biogeochemical processes. The overall aim characterize cover...
Abstract. Sea ice thickness information is important for sea modelling and ship operations. Here a method to detect the of up 50 cm during freeze-up season based on high incidence angle observations Soil Moisture Ocean Salinity (SMOS) satellite working at 1.4 GHz suggested. By comparison thermodynamic growth data with SMOS brightness temperatures, correlation intensity an anticorrelation difference between vertically horizontally polarised temperatures angles 40 50° are found used develop...
ABSTRACT The presence of leads with open water or thin ice is an important feature the Arctic sea cover. Leads regulate heat, gas and moisture fluxes between ocean atmosphere are areas high growth rates during periods freezing conditions. Here, algorithm providing automatic lead detection based on synthetic aperture radar images described that can be applied to a wide range Sentinel-1 scenes. By using both HH HV channels instead single co-polarised observations able classify more correctly....
Abstract. The presence of melt ponds on the Arctic sea ice strongly affects energy balance Ocean in summer. It albedo as well transmittance through ice, which has consequences for heat and mass ice. An algorithm to retrieve pond fraction from Medium Resolution Imaging Spectrometer (MERIS) data is validated against aerial, shipborne situ campaign data. results show best correlation landfast multiyear high concentrations. For broadband albedo, R2 equal 0.85, with RMS (root mean square) being...
Abstract Comparing helicopter‐borne surface temperature maps in winter and optical orthomosaics summer from the year‐long Multidisciplinary drifting Observatory for Study of Arctic Climate expedition, we find a strong geometric correlation between warm anomalies melt pond location following summer. Warm are associated with thinner snow ice, that is, depression refrozen leads, allow water accumulation during melt. January were 0.3–2.5 K warmer on sea ice later formed ponds. A one‐dimensional...
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. The spatial and temporal dynamics of melt ponds sea ice albedo contain information on the current state trend climate Arctic region. This publication presents a study pond fraction (MPF) obtained with Melt Pond Detection (MPD) retrieval scheme for Medium Resolution Imaging Spectrometer (MERIS) satellite data. compares MPF to surface air temperature reanalysis data, retrieved from Moderate Spectroradiometer (MODIS), examines trends. Weekly averages 2007 2011 showed different while...
The discrete dipole approximation (DDA) is a widely used method for simulation of various optical properties nanoparticles arbitrary shape and composition. We present modification the DDA to rigorously treat particles located above plane homogeneous substrate. based on discretization only particle itself retains three-dimensional fast Fourier transform acceleration scheme free-space DDA; hence, it has same order computational complexity. It implemented in recent version open-source ADDA...
Abstract. The spaceborne passive microwave sensors Soil Moisture Ocean Salinity (SMOS) and Active Passive (SMAP) provide brightness temperature data in the L band (1.4 GHz). At this low frequency atmosphere is close to transparent polar regions thickness of thin sea ice can be derived. SMOS measurements cover a large incidence angle range, whereas SMAP observes at fixed 40∘ angle. By using temperatures obtained directly (SMAP), or through interpolation (SMOS), retrieval more consistent as...
The FSSCat mission was the 2017 ESA Sentinel Small Satellite (S⌃3) Challenge winner and Copernicus Masters competition overall winner. It successfully launched on 3 September 2020 onboard VEGA SSMS PoC (VV16). aims to provide coarse downscaled soil moisture data over polar regions, sea ice cover, resolution thickness using a combined L-band microwave radiometer GNSS-Reflectometry payload. As part of calibration validation activities FSSCat, GNSS-R instrument deployed as MOSAiC expedition....
Abstract Research on improving the prediction skill of climate models requires refining quality observational data used for initializing and tuning models. This is especially true in polar regions where uncertainties about interactions between sea ice, ocean, atmosphere are driving ongoing monitoring efforts. The Copernicus Imaging Microwave Radiometer (CIMR) an European Space Agency (ESA) candidate mission which promises to offer high resolution, low uncertainty observation capabilities at...
Warm air intrusions over Arctic sea ice can change the snow and surface conditions rapidly alter concentration (SIC) estimates derived from satellite-based microwave radiometry without altering true SIC. Here we focus on two warm moist during Multidisciplinary drifting Observatory for Study of Climate (MOSAiC) expedition that reached research vessel Polarstern in mid-April 2020. After events, SIC deviations between different satellite products, including climate data records, were observed...
Observations of sea ice surface temperature provide crucial information for studying Arctic climate, particularly during winter. We examined 1 m resolution maps from 35 helicopter flights between October 2, 2019, and April 23, 2020, recorded the Multidisciplinary drifting Observatory Study Climate (MOSAiC). The seasonal cycle average spanned 265.6 K on to 231.8 January 28, 2020. was affected by atmospheric changes varied across scales. Leads in (cracks open water) were particular interest...
The influence of sea ice thickness brightness temperatures and concentrations retrieved from passive microwave observations is quantified, using horizontally homogeneous retrievals ESA's SMOS sensor at high incidence angles. Brightness are influenced by below 18 cm (89GHz) 50 (1.4 GHz). Ice concentration reduced 0.17 m 0.33 m, with higher frequency algorithms being less influenced.
This study investigates the distribution of Antarctic minke whales (AMW) in relation to sea ice concentration and variations therein. Information on AMW densities ice-covered parts Southern Ocean is required contextualize abundance estimates obtained from circumpolar shipboard surveys open waters, suggesting a 30% decline abundance. Conventional line-transect for density estimation are impossible regions, therefore we used icebreaker-supported helicopter obtain information along gradients...
Abstract Within a rapidly changing Arctic climate system, snow on sea ice is an important parameter. A common method to derive depth Arctic‐wide scale based passive microwave satellite observations. However, the uncertainties of this are not well constrained. In study, we estimate influence geophysical parameters, including ice, snow, and atmospheric properties retrievals using Monte Carlo uncertainty estimation. The results model simulations from Microwave Emission Model for Layered...
The ongoing decline of sea ice threatens many Arctic taxa, including the ivory gull. Understanding how ice-edges and concentrations influence distribution endangered gulls is a prerequisite to implementation adequate conservation strategies. From 2007 2013, we used satellite transmitters monitor movements 104 originating from Canada, Greenland, Svalbard-Norway Russia. Although half positions were within 41 km ice-edge (75% 100 km), approximately 80% on relatively highly concentrated ice....
Sea ice concentration algorithms using brightness temperatures (TB) from satellite microwave radiometers are used to compute sea (cice), extent, and generate climate data records (CDRs).Therefore, it is important minimize the sensitivity of cice estimates geophysical noise caused by snow/sea thermal emission signature variations, presence water vapor clouds in atmosphere and/or near-surface winds.In this study, we investigate effect leading systematic biases affecting standard deviations...
The sea ice surface temperature is important to understand the Arctic winter heat budget. We conducted 35 helicopter flights with an infrared camera in 2019/2020 during Multidisciplinary Drifting Observatory for Study of Climate (MOSAiC) expedition. were performed from a local, 5 10 km scale up regional, 20 40 scale. recorded thermal brightness temperatures, which we converted temperatures. More than 150000 images all can be investigated individually. As advanced data product, created maps...
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....
Abstract Monitoring surface and atmospheric parameters—like water vapor—is challenging in the Arctic, despite daily Arctic‐wide coverage of spaceborne microwave radiometer data. This is mainly due to difficulties characterizing sea ice emission: snow emission high highly variable. There are very few data sets combining relevant situ measurements with co‐located remote sensing data, which further complicates development accurate retrieval algorithms. Here, we present a multi‐parameter based...
Abstract. The frequent presence of cloud cover in polar regions limits the use Moderate Resolution Imaging Spectroradiometer (MODIS) and similar instruments for investigation monitoring sea-ice polynyas compared to passive-microwave-based sensors. very low thermal contrast between present clouds surface combination with lack available visible near-infrared channels during nighttime results deficiencies MODIS mask dependent data products. This leads misclassifications (i) as sea ice or open...
Abstract. We provide a new sea ice and water classification product with high spatial temporal coverage using Sentinel-1 Synthetic Aperture Radar (SAR) data. The is applied in the Fram Strait region Arctic during melting seasons, when contrast between backscatter intensities of different types observed by SAR reduced due to melted surface wet snow on ice. or strongly reduces penetration depth thus suppresses volume scattering contribution Furthermore, within marginal zone (MIZ)ambiguities...