A5066059700- Arctic and Antarctic ice dynamics
- Cryospheric studies and observations
- Climate change and permafrost
- Methane Hydrates and Related Phenomena
- Spacecraft and Cryogenic Technologies
- Marine and coastal ecosystems
- Climate variability and models
- Ocean Acidification Effects and Responses
- Ultrasonics and Acoustic Wave Propagation
- Atmospheric chemistry and aerosols
- Oceanographic and Atmospheric Processes
- Underwater Acoustics Research
University of Manitoba
2020-2024
Amrita Vishwa Vidyapeetham
2024
University of Calgary
2015-2023
Technical University of Denmark
2021
Finnish Meteorological Institute
2021
Universität Hamburg
2021
Norwegian Meteorological Institute
2021
Danish Meteorological Institute
2021
University of Bremen
2021
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. 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. In this study, we compare eight recently developed snow depth products over Arctic sea ice, which use satellite observations, modeling, or a combination of and modeling approaches. These are further compared against various ground-truth including those from ice mass balance observations airborne measurements. Large mean discrepancies observed the Atlantic Canadian sectors. The differences between climatology early in winter could be part result delaying formation that reduces...
Estimating sea ice motion from synthetic aperture radar (SAR) imagery at C-band is the most reliable approach because of its high spatial resolution and ever increasing temporal given multiple current upcoming SAR platforms. However, there still uncertainty in derived depending on type thermodynamic state. There have been suggestions (mostly theoretical) that use L-band inherent longer wavelength (15–30 cm) subsequent increased penetration capability could be beneficial for estimating...
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...
Identifying sea ice types in the early stages of development from L-band SAR imagery remains an active research area during Arctic freeze-up period. We used ScanSAR C- and RADARSAT-2, ALOS PALSAR ALOS-2 PALSAR-2, to identify North Water Polynya (NOW) Victoria Strait (VS) region Canadian Arctic. investigated HH-polarized microwave backscatter coefficient (σHH0) its GLCM texture parameters for six classes open water. found very low σHH0 nilas at both L-band. Although similar grey frequencies,...
Abstract We evaluate the effects of rapidly changing Arctic sea ice conditions on salt aerosols (SSA) produced by oceanic wave‐breaking and sublimation wind‐lofted salty blowing snow ice. use GEOS‐Chem chemical transport model to assess influence extent open ocean, multi‐year (MYI), first‐year (FYI), depths SSA emissions for 1980–2017. combine from Lagrangian snow‐evolution (SnowModel‐LG) together with an empirically‐derived salinity function depth derive spatially temporally varying surface...
Abstract Spring melt pond fraction ( f p ) has been shown to influence September sea ice extent and, with a growing need improve physics in climate and forecast models, observations at large spatial scales are needed. We present novel technique for estimating on high resolution from the Sentinel‐1 satellite during winter period leading up spring melt. A strong correlation r = −0.85) is found between radar backscatter first‐year multiyear data collected Canadian Arctic Archipelago (CAA) 2015....
Studying carbon dioxide in the ocean helps to understand how will be impacted by climate change and respond increasing fossil fuel emissions. The marine carbonate system is not well characterized Arctic, where challenging logistics extreme conditions limit observations of atmospheric CO2 flux acidification. Here, we present a high-resolution data set covering complete cycle sea-ice growth melt an Arctic estuary (Nunavut, Canada). This was collected through three consecutive yearlong...
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...
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....
We construct and present the first baseline, time series evolution of L-band SAR microwave backscatter (σ0HH) for landfast Arctic first-year (FYI) multi-year (MYI) sea ice from ALOS PALSAR. compare winter to freeze-up seasonal σ0HH signatures with C-band RADARSAT-2 imagery Ku-band QuikSCAT scatterometer data. also explored utility detect FYI MYI melt onset dates. For both types, exhibited a similar C- Ku-bands. A rise in was observed onset, however, lower magnitude attributed larger...
Abstract. Owing to differing and complex snow geophysical properties, radar waves of different wavelengths undergo variable penetration through snow-covered sea ice. However, the mechanisms influencing altimeter backscatter from ice, especially at Ka- Ku-band frequencies, impact on scattering horizon or “track point” (i.e. layer depth detected by re-tracker) are not well understood. In this study, we evaluate with respect ice floe buoyancy using a first-order model Archimedes principle. The...
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. Snow depth observations from airborne snow radars, such as the NASA's Operation IceBridge (OIB) mission, have recently been used in altimeter-derived sea ice thickness estimates, well for model parameterization. A number of validation studies comparing and situ measurements conducted western Arctic Ocean, demonstrating utility data. However, there no Atlantic sector Arctic. Recent this region suggest a significant predominant shift towards snow-ice regime caused by deep on thin...
Arctic sea ice is declining in areal extent and seasonal duration, affecting stable landfast regimes. These regimes are vital platforms for local indigenous subsistence hunters epontic primary production species supporting regional food webs. Under changing thermodynamic mechanical stresses, can become more prone to break out events - unexpected mid-season detachments from the coastline. However, prevalence of annual cycle on an interannual decadal basis generally understudied. Here, we...
Abstract The sub-kilometre scale distribution of snow depth on Arctic sea ice impacts atmosphere-ice fluxes energy and mass, is importance for satellite estimates sea-ice thickness from both radar lidar altimeters. While information about the mean this increasingly available modelling remote sensing, full cannot yet be resolved. We analyse 33 539 measurements 499 transects taken at Soviet drifting stations between 1955 1991 derive a simple statistical over multi-year as function only depth....
Thinning sea ice cover and earlier melt in the Arctic impact primary producer (PP) phenology, causing algal bloom termination phytoplankton commencement. However, logistic constraints limit capturing complete seasonal evolution of PPs their physical drivers. Here, we combine spectral irradiance data from subsurface oceanographic moorings with synthetic aperture radar backscatter meteorological variables to study light Dease Strait, investigating its relation timing magnitude surface for 2017...
Abstract. Snow thickness observations from airborne snow radars, such as the NASA’s Operation IceBridge (OIB) mission, have recently been used in altimeter-derived sea ice estimates, well for model parameterization. A number of validation studies comparing and situ measurements conducted western Arctic Ocean, demonstrating utility data. However, there no Atlantic sector Arctic. Recent this region suggest a significant predominant shift towards snow-ice regime, caused by deep on thin ice....
This study explores the potential of a multi-frequency (Ku-, X- and C-band) scatterometry approach, to understand microwave interactions between teo statistically different snow thickness covers (14cm 8cm) on first-year Arctic sea ice during late winter early-melt season transition. The results show substantial differences in backscatter response from all three frequencies, for both covers. Highly-saline with fluctuating geophysical thermodynamic properties cause these fluctuations,...
The presence of salt in the snow overlying seasonal sea ice has profound thermodynamic and electromagnetic effects. However, way that it arrives is distributed within marine snowpack remains poorly understood modelled. We describe two experiments tracing upward brine movement snow: one laboratory experiment at Rothera research station, West Antarctica, a field Hudson Bay, Canada. involved addition dyed to base terrestrial samples, with subsequent wicking being characterised. After initial...