Rosemary Willatt

Rosemary Willatt
University College London | UCL · Centre for Polar Observation and Modelling

PhD

About

20
Publications
2,447
Reads
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908
Citations
Citations since 2017
11 Research Items
596 Citations
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2017201820192020202120222023020406080100120
2017201820192020202120222023020406080100120
2017201820192020202120222023020406080100120
Introduction

Publications

Publications (20)
Article
Full-text available
Satellite observations of sea ice freeboard are integral to the estimation of sea ice thickness. It is commonly assumed that radar pulses from satellite-mounted Ku-band altimeters penetrate through the snow and reflect from the snow-ice interface. We would therefore expect a negative correlation between snow accumulation and radar freeboard measure...
Article
Full-text available
Arctic rain on snow (ROS) deposits liquid water onto existing snowpacks. Upon refreezing, this can form icy crusts at the surface or within the snowpack. By altering radar backscatter and microwave emissivity, ROS over sea ice can influence the accuracy of sea ice variables retrieved from satellite radar altimetry, scatterometers, and passive micro...
Preprint
Wind transport alters the snow topography and microstructure on sea ice through snow redistribution controlled by deposition and erosion. The impact of these processes on radar signatures is poorly understood. Here, we examine the effects of snow redistribution on Arctic sea ice from Ka- and Ku-band radar signatures. Measurements were obtained duri...
Article
Full-text available
The sub-kilometre scale distribution of snow depth on Arctic sea ice impacts atmosphere-ice fluxes of energy and mass, and is of importance for satellite estimates of sea-ice thickness from both radar and lidar altimeters. While information about the mean of this distribution is increasingly available from modelling and remote sensing, the full dis...
Preprint
Arctic rain-on-snow (ROS) deposits liquid water onto existing snowpacks. Upon refreezing, this can form icy crusts at the surface or within the snowpack. By altering radar backscatter and microwave emissivity, ROS over sea ice can influence the accuracy of sea ice variables retrieved from satellite radar altimetry, scatterometers, and passive micro...
Preprint
The sub-kilometre scale distribution of snow depth on Arctic sea ice impacts atmosphere-ice fluxes of energy and mass, and is of importance for satellite estimates of sea ice thickness from both radar and lidar altimeters. While information about the mean of this distribution is increasingly available from modelling and remote sensing, the full dis...
Article
Full-text available
Mean sea ice thickness is a sensitive indicator of Arctic climate change and is in long-term decline despite significant interannual variability. Current thickness estimations from satellite radar altimeters employ a snow climatology for converting range measurements to sea ice thickness, but this introduces unrealistically low interannual variabil...
Article
Full-text available
To improve our understanding of how snow properties influence sea ice thickness retrievals from presently operational and upcoming satellite radar altimeter missions, as well as to investigate the potential for combining dual frequencies to simultaneously map snow depth and sea ice thickness, a new, surface-based, fully polarimetric Ku- and Ka-band...
Article
Full-text available
Mean sea ice thickness is a sensitive indicator of Arctic climate change and in long-term decline despite significant interannual variability. Current thickness estimations from satellite radar altimeters employ a snow climatology for converting range measurements to sea ice thickness, but this introduces unrealistically low interannual variability...
Preprint
Full-text available
To improve our understanding of how snow properties influence sea ice thickness retrievals from presently operational and upcoming satellite radar altimeter missions, as well as investigating the potential for combining dual frequencies to simultaneously map snow depth and sea ice thickness, a new, surface-based, fully-polarimetric Ku- and Ka-band...
Article
Full-text available
Uncertainty in snow properties impacts the accuracy of Arctic sea ice thickness estimates from radar altimetry. On first-year sea ice (FYI), spatiotemporal variations in snow properties can cause the Ku-band main radar scattering horizon to appear above the snow/sea ice interface. This can increase the estimated sea ice freeboard by several centime...
Article
Satellite records show a decline in ice extent over more than three decades, with a record minimum in September 2012. Results from the Pan-Arctic Ice-Ocean Modelling and Assimilation system (PIOMAS) suggest that the decline in extent has been accompanied by a decline in volume, but this has not been confirmed by data. Using new data from the Europe...
Thesis
Sea ice is an important indicator of climate change. The ability to measure sea ice thickness is essential for monitoring trends in the volume of Arctic and Antarctic sea ice. Several methods of determining sea ice thickness are presented and it is concluded that the most appropriate for studying sea ice thickness trends on long time- and length-sc...
Article
Arctic sea ice has undergone major changes in recent years but there remains much uncertainty about its ultimate fate, in particular the timing of an ice-free Arctic in summer. Although satellite measurements of ice extent are well-established, wide-area measurements of sea ice thickness are key to understanding the fate of Arctic sea ice cover in...
Article
Understanding radar penetration through snow cover on sea ice is essential for sea ice thickness determination using radar altimetry. During the CryoSat Validation Experiment (CryoVEx) in April 2011, we investigated radar penetration into the snow pack. Ground data were collected at three field sites, in the pack ice (85.6 and 83.6N), and on fast i...
Article
Arctic sea ice has undergone major changes in recent years but there remains much uncertainty about its ultimate fate, in particular the timing of an ice-free Arctic in summer. Although satellite measurements of ice extent are well-established, wide-area measurements of sea ice thickness are key to understanding the fate of Arctic sea ice cover in...
Presentation
The European Space Agency (ESA) CryoSat-2 satellite, which was launched in April 2010, is designed to measure changes in the thickness of the polar ice caps. By means of radar altimetry, CryoSat-2 performs accurate measurements of sea ice freeboard, the height of the ice surface above the water level, which is related to ice thickness via isostasy....
Article
Satellite radar altimetry provides data to monitor winter Arctic sea-ice thickness variability on interannual, basin-wide scales. When using this technique an assumption is made that the peak of the radar return originates from the snow/ice interface. This has been shown to be true in the laboratory for cold, dry snow as is the case on Arctic sea i...
Article
Full-text available
Monitoring long-term, large-scale changes in the Antarctic sea ice thickness is not currently possible due to the sampling constraints of the ship-based and airborne observations which comprise most of the available thickness data. Satellite radar altimetry has been used to measure sea ice thickness variability in the Arctic where it is assumed tha...
Article
The binary nature of the bright (V = 4.2 mag) Mercury-Manganese star Phi Her has been known since 1976 and it was considered a low-amplitude single-lined SB. In a recent study we found evidence for lines of the secondary star. Other recent results from interferometry provide a good measure of the light ratio. It is very plausible that the secondary...

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