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Gloersen, P.

Publications and source records attributed to Gloersen, P..

At least 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

Polar sea ice observations by means of microwave radiometry

Principles pertinent to the utilization of 1.55 cm wavelength radiation emanating from the surface of the earth for studying the changing characteristics of polar sea ice are briefly reviewed. Recent data obtained at that wavelength with an imaging radiometer on-board the Nimbus 5 satellite are used to illustrate how the seasonal changes in extent of sea ice in both polar regions may be monitored free of atmospheric interference. Within a season, changes in the compactness of the sea ice are also observed from the satellite. Some substantial areas of the Arctic sea ice canopy identified as first-year ice in the past winter were observed not to melt this summer, a graphic illustration of the eventual formation of multiyear ice in the Arctic. Finally, the microwave emissivity of some of the multiyear ice areas near the North Pole was found to increase significantly in the summer, probably due to liquid water content in the firm layer.

Gloersen, P.↗
NASA NTRS1973

Microwave maps of the polar ice of the earth

Synoptic views of the entire polar regions of earth were obtained free of the usual persistent cloud cover using a scanning microwave radiometer operating at a wavelength of 1.55 cm on board the Nimbus-5 satellite. Three different views at each pole are presented utilizing data obtained at approximately one-month intervals during the winter of 1972-1973. The major discoveries resulting from an analysis of these data are as follows: (1) Large discrepancies exist between the climatic norm ice cover depicted in various atlases and the actual extent of the canopies. (2) The distribution of multiyear ice in the north polar region is markedly different from that predicted by existing ice dynamics models. (3) Irregularities in the edge of the Antarctic sea ice pack occur that have neither been observed previously nor anticipated. (4) The brightness temperatures of the Greenland and Antarctica glaciers show interesting contours probably related to the ice and snow morphologic structure.

Gloersen, P.↗
NASA NTRS1973

Microwave signatures of first-year and multiyear sea ice.

A combination of remote sensing from an aircraft and simultaneous surface measurements have confirmed the feasibility of identifying old and new sea ice according to its emission of thermal radiation at wavelengths between 0.3 and 3 cm. Emissivity of first-year thick ice with a surface temperature of about 260 K is 0.95 or greater for wavelengths between 0.81 and 11 cm; the emissivity of multiyear ice is 0.8 at 0.81 cm and 0.95 at 11 cm, increasing monotonically in this wavelength interval. The ease with which multiyear ice can be distinguished from first-year ice using a passive microwave radiometer is demonstrated by comparing mosaics prepared both from photographs and images of 1.55-cm radiation.

Gloersen, P.↗
NASA NTRS1973

Dynamics and morphology of Beaufort Sea ice determined from satellites, aircraft, and drifting stations

A series of measurements from drifting stations, aircraft, the ERTS-1, Nimbus 4, and Nimbus 5 satellites have jointly provided a new description of the dynamics and morphology of the ice cover of the Beaufort Sea. The combined analysis of these data show that the eastern Beaufort Sea ice cover is made up of large multiyear floes while the western part is made of small, predominantly first-year floes. The analysis suggests that this distribution might be quasi-steady and that the dynamics and thermodynamics of the region are more complex than hitherto known. The measurements consist of: (1) high resolution ERTS-1 imagery which is used to describe floe size and shape distribution, short term floe dynamics, and lead and polynya dynamics; (2) tracking by Nimbus 4 of IRLS drifting buoys to provide ice drift information which enhances the interpretation of the ERTS-1 imagery; (3) Nimbus 5 microwave (1.55 cm wavelength) imagery which provides synoptic, sequential maps on the distribution of multiyear and first-year ice types; (4) airborne microwave surveys and surface based observations made during 1971 and 1972 in conjunction with the AIDJEX (Arctic Ice Dynamics Joint Experiment) program.

Campbell, W. J.↗
NASA NTRS1973

Passive microwave images of lake ice

Photographic data and microwave emission images from the Great Lake ice formation are compared for their applicability to commercial shipping interests. A synoptic view of the microwave radiation from the lake area ice shows a large variation in brightness temperature. The snow ice appears to have the highest microwave brightness temperatures, whereas the thick clear ice shows up some 30 degrees kelvin colder, and the thin clear ice is colder still with a 1.55 cm radiation.

Gloersen, P.↗
NASA NTRS1972

Microwave signatures of first-year and multiyear sea ice

A combination of remote sensing from an aircraft and simultaneous surface measurements have confirmed the feasibility of identifying old and new sea ice according to its emission of thermal radiation at wavelengths between 0.3 and 3 cm. Emissivity of first-year thick ice with a surface temperature of about 260 K is 0.95 or greater for wavelengths between 0.81 and 11 cm; the emissivity of multiyear ice is 0.8 at 0.81 cm and 0.95 at 11 cm, increasing monotonically in this wave length interval. The ease with which multiyear ice can be distinguished from first-year ice using a passive microwave radiometer is demonstrated by comparing mosaics prepared both from photographs and images of 1.55 cm radiation.

Gloersen, P.↗
NASA NTRS1972

Arctic ice measurements with microwave radiometers

The application of microwave radiometers for measuring Arctic ice is discussed. The acquisition of Arctic ice data simultaneously on the surface with conventional instruments and remotely with microwave and infrared radiometers, photography, and a laser geodolite is described. A multifrequency view of a large multilayer ice floe is presented. The significance of the data recordings is explained.

Gloersen, P.↗
NASA NTRS1972

Microwave emission measurements of sea surface roughness, soil moisture, and sea ice structure

In order to demonstrate the feasibility of the microwave radiometers to be carried aboard the Nimbus 5 and 6 satellites and proposed for one of the earth observatory satellites, remote measurements of microwave radiation at wavelengths ranging from 0.8 to 21 cm have been made of a variety of the earth's surfaces from the NASA CV-990 A/C. Brightness temperatures of sea water surfaces of varying roughness, of terrain with varying soil moisture, and of sea ice of varying structure were observed. In each case, around truth information was available for correlation with the microwave brightness temperature. The utility of passive microwave radiometry in determining ocean surface wind speeds, at least for values higher than 7 meters/second has been demonstrated. In addition, it was shown that radiometric signatures can be used to determine soil moisture in unvegetated terrain to within five percentage points by weight. Finally, it was demonstrated that first year thick, multi-year, and first year thin sea ice can be distinguished by observing their differing microwave emissivities at various wavelengths.

Gloersen, P.↗
NASA NTRS1972

Microwave emission of Arctic Sea ice

The feasibility of carrying microwave radiometers on Nimbus E and F missions for sea ice surveys was studied in the arctic using aircraft. It was found that passive microwave signatures of Arctic Sea ice relate specifically to the structure and type of ice. It is concluded that a new tool for conducting ice surveys from aircraft and satellites with remote sensors was discovered.

Gloersen, P.↗