A Radar Profile of a Multi-year Pressure Ridge Fragment

... In May 1977, impulse radar was used to profile the thickness of an ice island and the first-year sea-ice near our camp site on Narwhal Island, Alaska. At this location, a small fragment of a multi-year pressure ridge was found with good access to the ridge crest. The impulse radar system was taken to the ridge so that it could be used to ascertain if thick multi-year ice could be measured and if the thickness of the ridge along the crest could be profiled. A cross-sectional profile of the ridge was not attempted, because the ice surface was buried under a thick layer of drift snow. The impulse radar profiling system consisted of an electronics console, a graphic recorder and an antenna. The system and its operational characteristics have been described in several publications. The radar antenna was pulled for a distance of 21 metres along the top of the ridge. ... The signal information shown is the travel time of the radar impulse signal to and from the various reflecting surfaces. These include the surface of the ridge, internal block structure, and the irregular surface of the keel. ... This report demonstrates the potential usefulness of impulse radar for determining the thickness of multi-year pressure ridges. ..

Remote Detection of Water Under Ice-covered Lakes on the North Slope of Alaska

Results from using an impulse radar sounding system on the North Slope of Alaska to detect the existence of water under lake ice are presented. It was found that both lake ice thickness and depth of water under the ice could be determined when the radar antenna was either on the ice surface or airborne in a helicopter. The findings also revealed that the impulse radar sounding system could detect where lake ice was bottom-fast and where water existed under the ice cover

Application of impulse radar to continuous profiling of tephra-bearing lake sediments and peats: an initial evaluation

Subsurface interface radar SIR, or impulse radar, uses electromagnetic pulses for continuous stratigraphic profiling. It has been applied to lake sediments (dy-gyttja) and peat deposits containing a sequence of thin, late Quaternary, ash-grade tephras at Lake Maratoto, North Island, New Zealand. The SIR system is very rapid, precise, and reasonably accurate compared with conventional coring and probing methods, but still requires good stratigraphic control for reliable interpretation. Radar penetration depths of up to 10 m were attained. Interfaces between lake bottom and lake sediments and underlying volcanogenic materials of varying lithologies could be readily discerned, as could many of the tephra layers preserved within the lake sediments. Peat depths and positions of stumps or logs on the surface of the subpeat materials could also be determined. Given adequate calibration by drilling, the SIR system appears useful for various shallow subsurface exploration studies, particularly those involving tephrostratig raphy and paleoenvironmental reconstructions from limnic and peat deposits, and in projects on buried wood

Remote Detection of a Freshwater Pool Off the Sagavanirktok River Delta, Alaska

... This field study has shown how an impulse radar ice profiling survey can be used to survey for fresh water in isolated pools under the ice cover of arctic river deltas. ..

Functional neuroimaging Using UWB Impulse Radar: a feasibility study

Microwave imaging is a promising new modality for studying brain function. In the current paper we assess the feasibility of using a single chip implementation of an ultra- wideband impulse radar for developing a portable and low-cost functional neuroimaging device. A numerical model is used to predict the level of attenuation that will occur when detecting a volume of blood in the cerebral cortex. A phantom liquid is made, to study the radar’s performance at different attenuation levels. Although the radar is currently capable of detecting a point reflector in a phantom liquid with submillimeter accuracy and high temporal resolution, object detection at the desired level of attenuation remains a challenge

Waterborne GPR survey for estimating bottom-sediment variability: A survey on the Po River, Turin, Italy

We conducted an integrated geophysical survey on a stretch of the river Po in order to check the GPR ability to discriminate the variability of riverbed sediments through an analysis of the bottom reflection amplitudes. We conducted continuous profiles with a 200-MHzGPR system and a handheld broadband EM sensor.Aconductivity meter and a TDR provided punctual measurements of water conductivity, permittivity, and temperature. The processing and interpretation of the GEM-2 and GPR data were enhanced by reciprocal results and by integration with the punctual measurements of the EM properties of the water. We used a processing flow that improved the radargram images and preserved the amplitude ratios among the different profiles and the frequency content at the bottom reflection signal.We derived the water attenuation coefficient both from the punctual measurements using the Maxwell formulas and from the interpretation of the GPR data, finding an optimal matching between the two values. The GPR measurements provided maps of the bathymetry and of the bottom reflection amplitude. The high reflectivity of the riverbed, derived from the GPR interpretation, agreed with the results of the direct sampling campaign that followed the geophysical survey. The variability of the bottom-reflection-amplitudes map, which was not confirmed by the direct sampling, could also have been caused by scattering phenomena due to the riverbed clasts which are dimensionally comparable to the wavelength of the radar pulse

A compact lightweight multipurpose ground-penetrating radar for glaciological applications

We describe a compact lightweight impulse radar for radio-echo sounding of subsurface structures designed specifically for glaciological applications. The radar operates at frequencies between 10 and 75 MHz. Its main advantages are that it has a high signal-to-noise ratio and a corresponding wide dynamic range of 132 dB due mainly to its ability to perform real-time stacking (up to 4096 traces) as well as to the high transmitted power (peak voltage 2800 V). The maximum recording time window, 40 ?s at 100 MHz sampling frequency, results in possible radar returns from as deep as 3300 m. It is a versatile radar, suitable for different geophysical measurements (common-offset profiling, common midpoint, transillumination, etc.) and for different profiling set-ups, such as a snowmobile and sledge convoy or carried in a backpack and operated by a single person. Its low power consumption (6.6 W for the transmitter and 7.5 W for the receiver) allows the system to operate under battery power for mayor que7 hours with a total weight of menor que9 kg for all equipment, antennas and batteries