EM-Bird Sensor Data - Product User Guide and Technical Specifications

This document provides a brief overview of the concept of sea-ice thickness sounding using airborne electromagnetic induction, the geophysical parameters sensed by a specific sensor type as well as a technical description of the content and format of the data files containing the unprocessed sensor data. The description of the higher-level geophysical data products is not part of this document and can be found in the scientific literature. Rather, the information here is intended to document the raw sensor data and the general method concept to ensure any use of the raw data in future applications

A glimpse beneath Antarctic sea ice: observation of platelet-layer thickness and ice-volume fraction with multi-frequency EM

In Antarctica, ice crystals (platelets) form and grow in supercooled waters below ice shelves. These platelets rise, accumulate beneath nearby sea ice, and subsequently form a several meter thick, porous sub-ice platelet layer. This special ice type is a unique habitat, influences sea-ice mass and energy balance, and its volume can be interpreted as an indicator of the health of an ice shelf. Although progress has been made in determining and understanding its spatio-temporal variability based on point measurements, an investigation of this phenomenon on a larger scale remains a challenge due to logistical constraints and a lack of suitable methodology. In the present study, we applied a lateral constrained Marquardt-Levenberg inversion to a unique multi-frequency electromagnetic (EM) induction sounding dataset obtained on the ice-shelf influenced fast-ice regime of Atka Bay, eastern Weddell Sea. We adapted the inversion algorithm to incorporate a sensor specific signal bias, and confirmed the reliability of the algorithm by performing a sensitivity study using synthetic data. We inverted the field data for sea-ice and platelet-layer thickness and electrical conductivity, and calculated ice-volume fractions within the platelet layer using Archie’s Law. The thickness results agreed well with drillhole validation datasets within the uncertainty range, and the ice-volume fraction yielded results comparable to other studies. Both parameters together enable an estimation of the total ice volume within the platelet layer, which was found to be comparable to the volume of landfast sea ice in this region, and corresponded to more than a quarter of the annual basal melt volume of the nearby Ekström Ice Shelf. Our findings show that multi-frequency EM induction sounding is a suitable approach to efficiently map sea-ice and platelet-layer properties, with important implications for research into ocean/ice-shelf/sea-ice interactions. However, a successful application of this technique requires a break with traditional EM sensor calibration strategies due to the need of absolute calibration with respect to a physical forward model

Social and Economic Activity of the Elder Generation in Tomsk Region

Social and economic activity of the Russian elder generation has a contradictory nature. On the one hand, Russian pensioners often continue working beyond the existing comparatively low retirement age, on the other hand, in terms of involvement in volunteering, political activities, and even in care for children and grandchildren they lag significantly behind the average European level. Explaining it only by the lack of time does not seem plausible, since in many European countries, the employment rates, involvement in unpaid work and caring for other family members are all higher than in Russia. In our study we attempt to identify reasons for lower social and economic activity of older adults in Russia as compared with European countries. We use data of Tomsk regional survey (2015, N=400) for accessing older adults' social activity. Data analysis on Tomsk region suggests that employment (as an activity) and education (as a prerequisite) contribute to higher involvement in social interactions in later life

Product User Guide & Algorithm Specification: AWI CryoSat-2 Sea Ice Thickness (version 2.2)

This document provides an overview of all aspects of the CryoSat-2 Arctic sea-ice thickness data product (version 2.2) generated at the Alfred Wegener Institute Helmholtz Center for Polar and Marine Research (AWI). It contains information on a) primary and auxiliary data sets used in the processing, b)description of the algorithm used deriving geophysical information along orbit segments and on space-time grids, c)t echnical specifications of the product files, d) data access and e) known Issues of the data recor

Comparison of sea-ice freeboard distributions from aircraft data and cryosat-2

The only remote sensing technique capable of obtain- ing sea-ice thickness on basin-scale are satellite altime- ter missions, such as the 2010 launched CryoSat-2. It is equipped with a Ku-Band radar altimeter, which mea- sures the height of the ice surface above the sea level. This method requires highly accurate range measure- ments. During the CryoSat Validation Experiment (Cry- oVEx) 2011 in the Lincoln Sea, Cryosat-2 underpasses were accomplished with two aircraft, which carried an airborne laser-scanner, a radar altimeter and an electro- magnetic induction device for direct sea-ice thickness re- trieval. Both aircraft flew in close formation at the same time of a CryoSat-2 overpass. This is a study about the comparison of the sea-ice freeboard and thickness dis- tribution of airborne validation and CryoSat-2 measure- ments within the multi-year sea-ice region of the Lincoln Sea in spring, with respect to the penetration of the Ku- Band signal into the snow

Not extinct yet: innovations in frequency domain HEM triggered by sea ice studies

The last 15 years have brought major innovations in helicopter towed time domain electromagnetics (EM), while few further developments have been made within the classic frequency domain segment. Operational use of frequency domain EM for sea ice thickness mapping acted as a driving force to develop new concepts such as the system under our consideration. Since its introduction we have implemented new concepts aiming at noise reduction and drift elimination. We decreased signal noise base levels by one to two orders of magnitude with changes to the signal transmission concept. Further, we increased the receiver coil dynamic range creating an EM setup without the need for primary field bucking. Finally, we implemented control signals inside the receiver coils to potentially eliminate system drift. Ground tests demonstrate the desired noise reduction and demonstrate drift control, leading to essentially drift free data. Airborne field data confirm these results, yet also show that the procedures can still be improved. The remaining quest is whether these specialised system improvements could also be implemented in exploration helicopter EM (HEM) systems to increase accuracy and efficiency