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W. Nordberg and Harry Press
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W. Nordberg and W. R. Bandeen

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W. Nordberg, L. Katchen, J. Theon, and W. S. Smith

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Pressure, density, temperature and wind measurements in the upper stratosphere and in the mesosphere resulted from a total of 53 rocket-grenade soundings conducted during the period 1960–1965. Most of the soundings were performed over North America (Wallops Island, 38N and Churchill, 59N) but some results were also obtained over the tropical Atlantic (Ascension Island, 8S) and over Northern Europe (Kronogard, 66N). Soundings were carried out simultaneously at these sites and were coordinated with soundings measing similar parameters over other areas of the globe.

Seasonal and latitudinal variations in the structure and circulation of this region of the atmosphere were derived from the results. Stratosphere temperatures vary with season and latitude in accordance with solar heating rates and with established circulation models. Temperatures above 65 km are substantially warmer in winter than in summer. Average seasonal temperature differences are about 40K at 80 km. They are very pronounced at midlatitudes (Wallops Island) and become even more extreme at high latitudes where in summer mesopause temperatures as low as 140K were observed. Maximum stratopause temperatures were observed during late winter-early summer. At Wallops Island these maxima of about 280K coincided with the period of transition from winter to summer circulation. Temperature profiles for all seasons at all sites intersect between 60 and 65 km at a temperature range of 230 to 240K.

The strong westerly flow in winter shows two pronounced cores, one persistent throughout the winter just above the stratopause, the other somewhat weaker and less persistent near 75 km. Deviations from the zonal flow indicate the existence of meteorological circulation cells on a synoptic scale with the average meridional flaw at Churchill strongly from the north during both summer and winter and at Wallops Island somewhat weaker from the south during the winter.

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W. Nordberg, J. Conaway, Duncan B. Ross, and T. Wilheit

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Measurements were made from aircraft of the 1.55-cm microwave emission from the North Sea and North Atlantic at surface wind speeds ranging from less than 5 to 25 m sec−1. Brightness temperatures in the nadir direction increased almost linearly with wind speed from 7 to 25 m sec−1 at a rate of about 1.2C (m sec−1)−1. At 70° from nadir the rate was 1.8C (m sec−1)−1. This increase was directly proportional to the occurrence of white water on the sea surface. At wind speeds <7 m sec−1, essentially no white water was observed and brightness temperatures in the nadir direction were ∼120K; at wind speeds of 25 m sec−1 white water cover was on the order of 30% and average brightness temperatures at nadir were −142K. Maximum brightness temperatures for foam patches large enough to fill the entire radiometer beam were 220K.

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W. Nordberg, A. W. McCulloch, L. L. Foshee, and W. R. Bandeen
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P. Gloersen, T. T. Wilheit, T. C. Chang, W. Nordberg, and W. J. Campbell

Synoptic views of the entire polar regions of Earth have been 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 December 1972 to February 1973. The major discoveries resulting from an analysis of these data are as follows: 1) Large discrepancies exist between the long-term 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 Antarctic glaciers show interesting contours probably related to the ice and snow morphologic structure.

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W. Nordberg, W. R. Bandeen, B. J. Conrath, V. Kunde, and I. Persano

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Three simple and typical cases of radiation fluxes measured by the TIROS III meteorological satellite are presented and discussed. These cases deal with emitted earth radiation received in three infrared channels and reflected solar radiation received in two visible channels over the tropical Atlantic, the eastern United States, and the North African desert. Each of the measurements is accompanied by results from a wide-field radiometer and photographs from TV cameras flown in the same satellite. The cases over the Atlantic Ocean and the African desert were in almost cloudless sides, while the case over the United States included regions ranging from heavily clouded to clear. Results show that the measurements from the various instruments and in the various channels are internally consistent. Maximum albedo values over the overcast arms were determined to be approximately 55 per cent. Over the ocean, albedos were near 7 per cent, and over land and clear skies the albedo varied from about 15 per cent over heavy vegetation to about 30 per cent over the desert. From these measurements total outgoing energy fluxes in the infrared were computed to be as high as 340 watts per square meter over the desert and as low as 190 watts per square meter over the cloudy areas. With the exception of the measurements made over the desert, results in the atmospheric window channel (7.5 to 13.5 microns) show substantial absorption, probably due to water vapor.

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J. S. Theon, W. Nordberg, L. B. Katchen, and J. J. Horvath

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Temperature and wind soundings of the stratosphere and mesosphere using the acoustic grenade technique were made over Barrow, Alaska (71N), during the arctic winter night and during the summer. The winter mesosphere temperatures were generally warmer than at any other location and season and were variable from day to day. Temperatures oscillated with height in wavelike fashion at magnitudes up to 30–40C between 70 and 90 km. These wavelike structures were found to exist also in the winter mesosphere at Churchill (59N) and Wallops Island (38N). However, the magnitude of the oscillations decreased with latitude to a value of 20–25C at Wallops. Conversely, variability In summer armed to decrease with increasing latitude and the wavelike structure was suppressed entirely at Barrow. Temperature variations in summer at Barrow were less than 10C from sounding to sounding at any given altitude from 40 to 85 km. Extremely low mesopause temperatures ranging from 130–140K near 85 km were observed in all of these soundings. One of the Barrow soundings, conducted during a noctilucent cloud display, when compared with a sounding conducted in the confirmed absence of noctilucent clouds, failed to show any significant temperature difference at the cloud level.

Simultaneous grenade soundings conducted from Wallops, Churchill and Barrow during 1965 indicate that a stratospheric warming which occurred over Barrow in late January-early February can be explained in terms of the circulation features at 50 km. Ridging of the Aleutian anticyclone over Alaska combined with the splitting and/or migration of the polar vortex center to a location southwest of Churchill, resulted in a 20–25C increase in the Barrow temperatures from 40–50 km during the 8-day period between soundings (27 January to 4 February). The third set of soundings made on 8 February shows that the original circulation pattern was restored with the polar vortex again centered north of the Arctic circle and the Aleutian anticyclone centered south of Alaska. The resulting circulation returned the Barrow temperature profile to its original value of 27 January and was accompanied by a weakening of the pressure gradient over North America which changed the strong northwesterly winds above Barrow to light and variable up to 70 km.

One set of grenade soundings at Wallops in November 1964, and four sets of pitot-tube soundings at Ascension Island in April 1964 and May 1965, and aboard ship in March and April 1965, were conducted each within one diurnal cycle. Wallops temperature variations observed at 45 km indicate a tendency toward a higher temperature near midnight than near local noon. This variation, a total of 15C at 45 km, increases with altitude to above 20C at 75 km. The phase of the cycle changes considerably also, and at 70 km the maximum occurs at local sunset and the minimum occurs near local sunrise. Results from the pitot-tube soundings indicate higher temperatures at night than in daytime at the stratopause, a rapidly changing phase of maximum temperature with height, and an increasing amplitude of the variations with height.

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