Engineering Papers⌕ Search

Engineering topics

Ramseier, R. O.

Publications and source records attributed to Ramseier, R. O..

14 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1984

Use of SIR-B multiincidence-angle imagery to study iceberg detectability and offshore ocean feature extraction

The Shuttle Imaging Radar B (SIR-B) iceberg experiment is described and expected results are outlined. The specific objectives are: (1) to study the L-band satellite SAR detectability of iceberg targets as a function of incidence angle and observed conditions; (2) to compare L-, X-, and C-band aircraft imagery, and to use this data as a basis for an appropriate simulation of satellite imagery and to compare with SIR-B images; and (3) to determine the possibility of comparive available surface or near surface currents with estimates of the range component of surface current derived from the SIR-B data (IOS experiment).

Gray, A. L.↗
NASA NTRS1982

Sea-Ice Mission Requirements for the US FIREX and Canada RADARSAT programs

A bilateral synthetic aperture radar (SAR) satellite program is defined. The studies include addressing the requirements supporting a SAR mission posed by a number of disciplines including science and operations in sea ice covered waters. Sea ice research problems such as ice information and total mission requirements, the mission components, the radar engineering parameters, and an approach to the transition of spacecraft SAR from a research to an operational tool were investigated.

Carsey, F. D.↗
NASA NTRS1980

Arctic sea-ice variations from time-lapse passive microwave imagery

This paper presents: (1) a short historical review of the passive microwave research on sea ice, which established the observational and theoretical base permitting the interpretation of the first passive microwave images of earth obtained by the Nimbus-5 ESMR; (2) the construction of a time-lapse motion picture film of a 16-month set of serial ESMR images to aid in the formidable data analysis task; and (3) a few of the most significant findings resulting from an early analysis of these data, using selected ESMR images to illustrate these findings.

Campbell, W. J.↗
NASA NTRS1979

Antarctic Sea Ice variations 1973 - 1975

Variations in the extent and concentration of sea ice cover on the Southern Ocean are described for the three-year period 1973-75 using information derived from the Nimbus-5 passive microwave imager.

Zwally, H. J.↗
NASA NTRS1978

Ice sheet topography by satellite altimetry

The measured time between the transmission and rzturn of 13.9 GHz radar pulses from the GEOS 3 satellite (at a mean altitude of 844.5 km and an inclination of 114 deg 52 min) is used to determine the thickness of the Greenland ice cap, with an accuracy in surface elevation on the order of 2 m. Attention is given to changes in ice thickness as an indicator of climatic change in general, and change in mean sea level in particular. Each elevation data point obtained by the satellite represents an average along 0.67 km of ground track, and three-dimensional maps are presented to illustrate the data.

Brooks, R. L.↗
NASA NTRS1978

Microwave remote sensing of sea ice in the AIDJEX Main Experiment

A microwave remote sensing program of sea ice in the Beaufort Sea was conducted during the Arctic Ice Dynamics Joint Experiment (AIDJEX). Several types of both passive and active sensors were used to perform surface and aircraft measurements during all seasons of the year. In situ observations were made of physical properties (salinity, temperature, density, surface roughness), dielectric properties, and passive microwave measurements were made of first-year, multiyear, and first-year/multiyear mixtures. Airborne passive microwave measurements were performed with the electronically scanning microwave radiometer while airborne active microwave measurements were performed by synthetic aperture radar, X- and L-band radar, and a scatterometer.

Campbell, W. J.↗
NASA NTRS1978

Time-dependence of sea-ice concentration and multiyear ice fraction in the Arctic Basin

Microwave images of sea ice obtained by Nimbus-5 and the NASA CV-990 airborne laboratory are used to determine the time variation of the sea-ice concentration and multiyear ice fraction within the pack ice in the Arctic Basin. The images, constructed from data acquired from the electrically scanned microwave radiometer, are analyzed for four seasons during 1973-1975. Observations indicate significant variations in the sea-ice concentration in the spring, late fall, and early winter. Sea-ice concentrations as low as 50% were detected in large areas in the interior of the Arctic polar sea-ice pack. The applicability of passive-microwave remote sensing for monitoring the time dependence of sea-ice concentration is considered.

Gloersen, P.↗
NASA NTRS1976

Beaufort Sea ice zones as delineated by microwave imagery

Microwave and infrared data were obtained from a research aircraft over the Beaufort Sea ice from the shoreline of Harrison Bay northward to a latitude of almost 81 deg N. The data acquired were compared with microwave data obtained on the surface at an approximate position of 75 deg N, 150 deg W. Over this north-south transect of the polar ice canopy it was discovered that the sea ice could be divided into five distinct zones. The shorefast sea ice was found to consist uniformly of first-year sea ice. The second zone was found to be a mixture of first-year sea ice, medium size multiyear floes, and many recently refrozen leads, polynyas, and open water; considerable shearing activity was evident in this zone. The third zone was a mixture of first-year and multiyear sea ice which had a uniform microwave signature. The fourth zone was found to be a mixture of first-year sea ice and medium-to-large size multiyear floes which was similar in composition to the second zone. The fifth zone was almost exclusively multiyear ice extending to the North Pole.

Campbell, W. J.↗
NASA NTRS1976

An integrated approach to the remote sensing of floating ice

Review article on remote sensing applications to glaciology. Ice parameters sensed include: ice cover vs open water, ice thickness, distribution and morphology of ice formations, vertical resolution of ice thickness, ice salinity (percolation and drainage of brine; flushing of ice body with fresh water), first-year ice and multiyear ice, ice growth rate and surface heat flux, divergence of ice packs, snow cover masking ice, behavior of ice shelves, icebergs, lake ice and river ice; time changes. Sensing techniques discussed include: satellite photographic surveys, thermal IR, passive and active microwave studies, microwave radiometry, microwave scatterometry, side-looking radar, and synthetic aperture radar. Remote sensing of large aquatic mammals and operational ice forecasting are also discussed.

Campbell, W. J.↗
NASA NTRS1975

Skylab floating ice experiment

The author has identified the following significant results. Coupling of the aircraft data with the ground truth observations proved to be highly successful with interesting results being obtained with IR and SLAR passive microwave techniques, and standard photography. Of particular interest were the results of the PMIS system which operated at 10.69 GHz with both vertical and horizontal polarizations. This was the first time that dual polarized images were obtained from floating ice. In both sea and lake ice, it was possible to distinguish a wide variety of thin ice types because of their large differences in brightness temperatures. It was found that the higher brightness temperature was invariably obtained in the vertically polarized mode, and as the age of the ice increases the brightness temperature increases in both polarizations. Associated with this change in age, the difference in temperature was observed as the different polarizations decreased. It appears that the horizontally polarized data is the most sensitive to variations in ice type for both fresh water and sea ice. The study also showed the great amount of information on ice surface roughness and deformation patterns that can be obtained from X-band SLAR observations.

Campbell, W. J.↗
NASA NTRS1975

Beaufort sea ice zones by means of microwave imagery

An analysis of the aircraft microwave data obtained during the AIDJEX pilot experiment is presented and compared with a recent analysis of the microwave brightness temperatures measured in situ in the vicinity of the n main AIDJEX camp. The sea ice is divided into five distinct zones, the properties of each are discussed in detail.

Gloersen, P.↗
NASA NTRS1975

Geophysical studies of floating ice by remote sensing

This paper presents an overview of recent remote-sensing techniques as applied to geophysical studies of floating ice. The current increase in scientific interest in floating ice has occurred during a time of rapid evolution of both remote-sensing platforms and sensors. Mesoscale and macroscale studies of floating ice are discussed under three sensor categories: visual, passive microwave, and active microwave. The specific studies that are reviewed primarily investigate ice drift and deformation, and ice type and ice roughness identification and distribution.

Campbell, W. J.↗
NASA NTRS1974

Results of the US contribution to the joint US/USSR Bering Sea experiment

The atmospheric circulation which occurred during the Bering Sea Experiment, 15 February to 10 March 1973, in and around the experiment area is analyzed and related to the macroscale morphology and dynamics of the sea ice cover. The ice cover was very complex in structure, being made up of five ice types, and underwent strong dynamic activity. Synoptic analyses show that an optimum variety of weather situations occurred during the experiment: an initial strong anticyclonic period (6 days), followed by a period of strong cyclonic activity (6 days), followed by weak anticyclonic activity (3 days), and finally a period of weak cyclonic activity (4 days). The data of the mesoscale test areas observed on the four sea ice option flights, and ship weather, and drift data give a detailed description of mesoscale ice dynamics which correlates well with the macroscale view: anticyclonic activity advects the ice southward with strong ice divergence and a regular lead and polynya pattern; cyclonic activity advects the ice northward with ice convergence, or slight divergence, and a random lead and polynya pattern.

Campbell, W. J.↗