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S. FRITZ

Abstract

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S. FRITZ
and
H. WEXLER

Abstract

Some of the more striking examples of cloud phenomena revealed by the first pictures that have come from the experimental weather satellite, TIROS I, are presented, and broad-scale patterns in the pictures are interpreted in terms of general features of the associated weather maps. These preliminary results show that a vast variety of scales appear in the cloud patterns associated with cyclonic vortices. Marked differences, as well as similarities, in cloud patterns associated with several types of cyclones are pointed out; the cyclones discussed include mature vortices in the Atlantic and Pacific Oceans, younger cyclones over and near the United States, and a typhoon in the South Pacific Ocean. The cloud cover over an extensive area is portrayed by means of preliminary mosaics of TIROS pictures and by a schematic cloud map made from the pictures.

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I. ENGER
and
S. FRITZ

Abstract

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S. FRITZ
and
S. D. SOULES

Abstract

Radiances emitted from the atmosphere near 669.3 cm−1 in the center of the 15-µm CO2 band were measured from the Nimbus 3 satellite. Changes in observed radiance correspond to weighted temperature changes of the upper 100 mb of air. The seasonal march of latitudinally averaged radiances is presented from 80°N to 80°S. The latitudinal and seasonal variations of radiance are removed from the data. The residuals emphasize the fact that winter polar stratospheric warmings are accompanied by stratospheric coolings in the Tropics and summer hemisphere. A warming of about 7°K near latitude 50° is accompanied by a cooling of about 1°K at the Equator. However, much larger warmings at latitudes near the poles do not produce correspondingly large coolings at the Equator.

The synoptic distributions of radiances on 2 days are discussed: (1) the day when the average latitudinal radiance was a minimum in polar latitudes and (2) the day when the polar warming reached its maximum. The wave number 1 pattern in middle and high latitudes of the Northern (winter) Hemisphere is evident. In the Southern (summer) Hemisphere, wave numbers 2 and 3 dominate. The large latitudinal difference of the radiances, on the day before the warming begins, reaches a value corresponding to about 15°K between 30° and 50°N at about 20°W longitude.

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S. Fritz
and
S. D. Soules

Abstract

The radiances in the CO2 band centered at 669.3 cm−1 (15 μ), measured by the satellite infrared spectrometer on Nimbus III, are examined. These radiances are a measure of a weighted mean temperature of approximately the upper 100 mb of the atmosphere. A new result shows that stratospheric warmings in the winter hemisphere are accompanied by simultaneous coolings in the stratosphere of the tropics and the summer hemisphere. These out-of-phase changes of stratospheric temperature may be explained by heat transfer changes caused by variations of the meridional circulation and large-scale eddies.

The out-of-phase relationship in stratospheric temperature is evident in the radiances when averaged around latitude circles, although the changes observed on certain dates do not occur at all longitudes. The isotherms in the stratosphere tend to be more nearly circumpolar on a day with minimum radiance. On a day when the warming reached its maximum, the higher radiances occur only in one part of the latitude zone. Widespread cooling in the tropics takes place while the warming progresses in the winter hemisphere, and eventually it occurs at all longitudes in a broad latitudinal zone in the tropics and the summer hemisphere.

The atmosphere seems to act like a standing wave in which the amplitude of the temperature changes are larger in the middle and high latitudes of the winter hemisphere than in the tropics and summer hemisphere. The nodal point moved somewhat with the season, between about 25–45S, during the Southern Hemisphere winter.

Radiance data also show the seasonal trend of stratospheric temperature from 8ON to 80S. The expected seasonal variation is found in middle and high latitudes; however, the winter radiances at 80S are not as cold in relation to the winter radiances at 8ON as might be expected from climatological temperatures up to 30 mb.

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S. Fritz
and
P. Krishna Rao

Abstract

On the basis of satellite and other types of information, it is shown, both on observational and theoretical grounds, that cirrus clouds have a higher transmission for radiation at 10 μ than for radiation at 6 μ. Thus, in the case studied, at 10 μ the cirrus clouds had a fractional transmission of about 50%, while at 6 μ the clouds were essentially opaque. This fact has an important bearing on attempts to use a “humidity diagram” to estimate relative humidity above clouds. The satellite data show that measurements at 6 or 10 μ can be used to locate regions of substantial cloudiness, which are therefore regions of high relative humidity in the troposphere. To use these satellite measurements to estimate the relative humidity above clouds would be misleading. However, the use of radiation measurements in both channels can perhaps be helpful for specifying the transmissivity of cirrus clouds, and in the absence of clouds, for locating regions of low relative humidity.

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S. FRITZ
and
T. H. MacDONALD

Abstract

Normal-incidence solar radiation values were measured during the IGY at the South Pole and Little America (Antarctica), at Mauna Loa (Hawaii), Tucson (Arizona), and Blue Hill Observatory (Massachusetts); some results are given in tables and graphs. Essential differences among them are discussed. The radiation data at Tucson and Blue Hill are appreciably lower than at the other stations. The radiation, corrected for solar distance, is similar at the Antarctic stations to the radiation measured at Mauna Loa. However, the actual measured values in summer are higher at the South Pole than at Mauna Loa, because the sun is closer to the earth in the Southern Hemisphere summer. The “extrapolated turbidity factor” is over 2.5 at Tucson and Blue Hill, but averages 2.0 or less at the other stations with the lowest values of about 1.5 at the South Pole.

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SIGMUND FRITZ
and
JAY S. WINSTON

Abstract

TIROS II measurements of infrared radiation in the 10-micron “water-vapor window” on one orbital pass over the United States are examined in detail relative to the field of cloudiness as derived from TIROS II television pictures and from other meteorological data. The radiation data are found to portray clearly the large-scale systems of middle and dense high cloud overcast, a capability that exists both day and night. Through use of information about the vertical and horizontal temperature fields, useful quantitative estimates of the heights of the tops of cloud systems are derived. In cases where there is a low overcast, the window measurements in themselves may not distinguish clouds from clear areas; but during daytime if television pictures are available, the window measurements can clearly show where a cloud overcast is low in height. Some tentative conclusions about the partial transparency of cirrus clouds to infrared radiation are also presented.

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S. Fritz
,
P. Krishna Rao
, and
M. Weinstein

Abstract

A method is described for comparing satellite measurements of reflected solar radiation with pryheliometric measurements at the ground and with measurements from airplanes. When data from accurate, well-calibrated satellite instruments become available, this method can be used to compute the solar energy absorbed directly in the atmosphere. In the meantime the method is applied to solar radiation measurements from TIROSIII, although these data are of doubtful accuracy.

TIROSIII measured the solar energy reflected by the planet Earth. Several of these measurements, taken over the United States near noon on 12 July 1963 are described. The corresponding “albedos” which varied from 0.65 over a bright overcast area to 0.05 over some cloudless areas, may be too low. The reflected energy is correlated with pyrheliometer measurements at the ground at 31 stations. The correlation coefficient was −0.9. The relationship between the satellite measurement and the ground pyrheliometer measurements is further compared with similar measurements made from airplanes in previous years. It is this comparison which suggests that the satellite measurements of albedo may he too low.

From the satellite measurements and the ground pyrheliometer measurements, the solar energy absorbed by the atmosphere itself can be computed after reasonable assumptions about the ground albedo are made. These absorptions sometimes exceed 35 per cent of the solar energy entering the top of the atmosphere; the values appear to be too large and are a consequence of the relatively low satellite values of measured reflectivity over cloudy areas.

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S. FRITZ
,
L. F. HUBERT
, and
A. TIMCHALK

Abstract

The degree of organization and the size of the cloud patterns in TIROS pictures of tropical disturbances are good indicators of the maximum wind speed as observed by airplanes. The organization varies from unorganized bright cloud patterns, to highly organized spiral arrays of clouds with additional characteristic features, such as the sharp edge of cirrus clouds. Poorly organized clouds are associated with weak disturbances, the most highly organized ones with intense storms.

In addition, within each category a relationship exists between the size of the cloud pattern and the maximum wind speed. Both the organization category and the size of the overcast cloud pattern are related statistically to the maximum wind speed, so that the maximum wind speed can be estimated from the picture of the storm alone. Tests with independent data show that a useful relationship has been obtained. Theoretical justification for the results obtained is necessary but is not yet available.

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