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The third Applications Technology Satellite (ATS-3) of the National Aeronautics and Space Administration (NASA) was launched into a geo-synchronous orbit at 35,800 km altitude over Brazil on 5 November 1967. One of the meteorological experiments onboard is the Multicolor Spin-Scan Cloud Camera. It provides instantaneous high resolution color pictures of the whole disc of the Earth in a 30-min sequence. Three images are obtained by simultaneous scanning through three different color filters (green, red, blue). The three separate signals are transmitted to the ground station where the multicolor picture is produced.
The first picture of 10 November 1967 is shown on the front page of this Bulletin. The superiority over monochrome pictures (black and white) is demonstrated by the strikingly better contrast between clouds and the background (Earth surface).
A large number of interesting meteorological details are shown in the picture and pointed out in this article. A montage of the ATS-3 picture and an ATS-1 photograph taken on the same day over the Pacific Ocean provides a synoptic picture of the cloud distribution over more than two thirds of the globe.
These successful experiments constitute a large step in obtaining a complete survey on short-time changes of global cloudiness as required for the World Weather Watch.
The third Applications Technology Satellite (ATS-3) of the National Aeronautics and Space Administration (NASA) was launched into a geo-synchronous orbit at 35,800 km altitude over Brazil on 5 November 1967. One of the meteorological experiments onboard is the Multicolor Spin-Scan Cloud Camera. It provides instantaneous high resolution color pictures of the whole disc of the Earth in a 30-min sequence. Three images are obtained by simultaneous scanning through three different color filters (green, red, blue). The three separate signals are transmitted to the ground station where the multicolor picture is produced.
The first picture of 10 November 1967 is shown on the front page of this Bulletin. The superiority over monochrome pictures (black and white) is demonstrated by the strikingly better contrast between clouds and the background (Earth surface).
A large number of interesting meteorological details are shown in the picture and pointed out in this article. A montage of the ATS-3 picture and an ATS-1 photograph taken on the same day over the Pacific Ocean provides a synoptic picture of the cloud distribution over more than two thirds of the globe.
These successful experiments constitute a large step in obtaining a complete survey on short-time changes of global cloudiness as required for the World Weather Watch.
The generally held assumption, that the bulk of tropical rain over the oceans is generated where the sea is warmer than the air, is being largely verified in this article with the new tool of satellite cloudiness mapping. The discussion focuses on the satellite-observed variable position of the boundary between the west Pacific equatorial rain clouds over warm ocean water and the east Pacific aridity along the equator over cool upwelling water. The often quite abrupt changes between these two regimes in the mid-Pacific are known from an eighteen-year sequence of ocean and atmosphere data at Canton Island. This article describes the same phenomena delineated by satellite television data recorded during 1962–67, and adds features of the geographic cloudiness distribution not obtainable from the widely spaced fixed points of observation.
The generally held assumption, that the bulk of tropical rain over the oceans is generated where the sea is warmer than the air, is being largely verified in this article with the new tool of satellite cloudiness mapping. The discussion focuses on the satellite-observed variable position of the boundary between the west Pacific equatorial rain clouds over warm ocean water and the east Pacific aridity along the equator over cool upwelling water. The often quite abrupt changes between these two regimes in the mid-Pacific are known from an eighteen-year sequence of ocean and atmosphere data at Canton Island. This article describes the same phenomena delineated by satellite television data recorded during 1962–67, and adds features of the geographic cloudiness distribution not obtainable from the widely spaced fixed points of observation.
Abstract
Nimbus II High Resolution Infrared Radiometer (HRIR) data, sensitive in the 3.4–4.2 μ window, were analyzed over several oceanic regions. Current boundaries such as the north wall of the Gulf Stream have been located consistently within 10 km of the positions indicated by airplane radiation data. With present techniques, primarily designed for meteorological purposes, the Gulf Stream boundary has been seen, at least in significant parts, in about 50 out of 175 days. Similar results have also been obtained in analyses of the Agulhas Current boundary, and the boundary between the Brazil and Falkland Currents. The satellite radiation observations suggest that the Brazil-Falkland Current boundary which is associated with a surface temperature gradient is as sharp and strong as the Gulf Stream North Wall. The Agulhas Current exhibits a similar temperature gradient along its western boundary, separating it from the Benguela Current surface waters.
Comparisons of equivalent blackbody temperatures over the Gulf Stream from Nimbus II with low flying radiometer-equipped aircraft showed that the satellite data were on the average 0.5C warmer.
Seasonal sea surface temperature variations of 9C over the Persian Gulf and Somali region and the upwelling along the Somali Coast during the southwest monsoon were clearly detected in the nighttime HRIR data.
Daytime observations within the 3.4–4.2 μ window have also shown qualitatively the location of major current boundaries.
Abstract
Nimbus II High Resolution Infrared Radiometer (HRIR) data, sensitive in the 3.4–4.2 μ window, were analyzed over several oceanic regions. Current boundaries such as the north wall of the Gulf Stream have been located consistently within 10 km of the positions indicated by airplane radiation data. With present techniques, primarily designed for meteorological purposes, the Gulf Stream boundary has been seen, at least in significant parts, in about 50 out of 175 days. Similar results have also been obtained in analyses of the Agulhas Current boundary, and the boundary between the Brazil and Falkland Currents. The satellite radiation observations suggest that the Brazil-Falkland Current boundary which is associated with a surface temperature gradient is as sharp and strong as the Gulf Stream North Wall. The Agulhas Current exhibits a similar temperature gradient along its western boundary, separating it from the Benguela Current surface waters.
Comparisons of equivalent blackbody temperatures over the Gulf Stream from Nimbus II with low flying radiometer-equipped aircraft showed that the satellite data were on the average 0.5C warmer.
Seasonal sea surface temperature variations of 9C over the Persian Gulf and Somali region and the upwelling along the Somali Coast during the southwest monsoon were clearly detected in the nighttime HRIR data.
Daytime observations within the 3.4–4.2 μ window have also shown qualitatively the location of major current boundaries.
Abstract
The presence or absence of clouds, their characteristics, and variations of surface albedo have been correlated with observations made at several different wavelengths in the visible spectrum. These were made at high and low nighttime light levels by an airglow photometer aboard the OGO-4 satellite during August 1967 through January 1968. The wavelength regions studied were approximately 50 Å bands centered at 3914, 5577, 5893, 6225 and 6300 Å, in the energy range of 10−7 to 10−3 erg cm−2 sec−1 Å−1 ster−1 with a field of view of ˜10 degrees. It was found that at the longer wavelengths (6225 and 6300 Å) the observations were strongly influenced by the variations of surface albedo. At the shorter wavelengths, the surface albedo variations were partly masked by the light returned through Rayleigh and Mie scattering. Preliminary analysis is made of surface and clouds by study of reflective radiance under moonlight and other nocturnal illuminations. Possibilities of further analysis are examined including methods of deducing cloud height information.
Abstract
The presence or absence of clouds, their characteristics, and variations of surface albedo have been correlated with observations made at several different wavelengths in the visible spectrum. These were made at high and low nighttime light levels by an airglow photometer aboard the OGO-4 satellite during August 1967 through January 1968. The wavelength regions studied were approximately 50 Å bands centered at 3914, 5577, 5893, 6225 and 6300 Å, in the energy range of 10−7 to 10−3 erg cm−2 sec−1 Å−1 ster−1 with a field of view of ˜10 degrees. It was found that at the longer wavelengths (6225 and 6300 Å) the observations were strongly influenced by the variations of surface albedo. At the shorter wavelengths, the surface albedo variations were partly masked by the light returned through Rayleigh and Mie scattering. Preliminary analysis is made of surface and clouds by study of reflective radiance under moonlight and other nocturnal illuminations. Possibilities of further analysis are examined including methods of deducing cloud height information.
