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W. Ho, H. H. Wang, W. F. Hall, W. Norris, W. N. Hardy, K. W. Gray, and G. M. Hidy

hasbeen extensively investigated by many workers in thefield and was first calculated by Hogg (1959) from theVan Vleck-Weisskopf line-shape theory for oxygenabsorption. The experimental observations from 0.3 to10 GHz have been reviewed by Medd and Fort (1966)and Howell and Shakeshaft (1967). Fig. 1 shows thesununary of the observations to date. These resultsinclude, in addition to the references given in the reviewartlcles~ the more recent measurements of Penzias andWilson (1967) at 1.415 GHz and

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X. Zou, S. Yang, and P. S. Ray

that provide the vertically integrated cloud ice water path but with better horizontal resolution ( King et al. 2003 , 2004 ; Platnick et al. 2001 ; Weng and Grody 2000 ). In visible and infrared wavelengths, satellite observations can be used to estimate cloud ice water path associated with optically thin clouds such as cirrus. For passive microwave sensors at frequencies higher than 85 GHz, cloud ice water path and particle mean size can be estimated simultaneously ( Weng and Grody 2000

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David Painemal, Patrick Minnis, and Larry O'Neill

from these passive microwave radiometers has been estimated at 25 g m −2 ( Wentz 1997 ; Wentz and Meissner 2000 ). While uncertainties in passive microwave estimates of LWP can occur from precipitation and relatively large frozen water particles [see the summary in O'Dell et al. (2008) ], neither is significant in the southeastern Pacific as precipitation is generally light and frozen water is infrequent. b. In situ observations In situ cloud-top temperature and height are used to establish the

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K. V. Beard and A. R. Jameson

predicts small canting angles, with the tangent ofth~ angle having a Gaussianprobability distribution about a mean value of zero. Previous reports of large canting angles above ~he surfacelayer were based upon interpretations of microwave measurements which were found to be sensitive to theassumed drop shapes and size distributions. However, past measurements using a circular polarization radartechnique, sensitive to canting but not to drop shapes and distributions, yielded a narrow distribution

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Louis J. Battan and John B. Theiss

974 JOURNAL OF THE ATMOSPHERIC SCIENCES VOLUa~E27Depolarization of Microwaves by Hydrometeors in a ThunderstormI Lo~s J. B~AS A~O Joss B. Tm~IssInstitute of A tmospkerlc Physics, The University of A ri~ona, Tucson(Manuscript received 2 March 1970)ABSTRACT Observations were made of the depolarization of 3-cm radar signals by hydrometeors in a thunderstorm.Observations of backscattered power and Doppler

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D. D. Turner, D. C. Tobin, S. A. Clough, P. D. Brown, R. G. Ellingson, E. J. Mlawer, R. O. Knuteson, H. E. Revercomb, T. R. Shippert, W. L. Smith, and M. W. Shephard

instruments is shown in Fig. 1 . The radiance differences are smaller than 0.5 mW m −2 sr −1 cm −1 [hereafter referred to as a radiance unit (RU)]. More details on the AERI instrument, how it is calibrated, and the uncertainties in its observations are provided by Knuteson et al. (2004a , b) . c. Microwave radiometer The MWRs used by the ARM program are Radiometrics WVR-1100 radiometers. They are two-channel units that measure downwelling radiation at 23.8 and 31.4 GHz. Water vapor emission dominates

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J. V. Evans and R. P. Ingalls

) or ammonia clouds (Rea4). REFERENCESBarrett, A. H., 1961: Microwave absorption and emission in the atmosphere of Venus. Astrophys. J., 133, 281-293.---, and Staelin, D. H., 1964: Radio observations of Venus and the interpretations. Space Sci. R**., 3, 109-135.Carpenter, R. L., 1966: Study of Venus by cw radar. Astron. J., 71, 142-152.Eshleman, V. R., 1967: Radar astronomy. Science, 158, 585-597.Evans, J. V., 1966: Radar signatures of the planets. Ann N. I& Acad. Sci., 140, 196

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Lawrence P. Giver, Robert W. Boese, and Jacob H. Miller

is in preparation. Comparison of these measurements with the dataof Rank et al. (1966) shows that NHs self-broadening isfar more effective than broadening by I-I2. The ratio ofself to H2 broadening that we found for the red band isin qualitative agreement with the values published forNHa microwave lines, viz., 9:1 reported by Townes andSchawlow (1955) and 7.9:1 by Legan et al. (1965). Because the effect of pressure broadening of NHa islarge even at 0.250 arm, we also obtained the red

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Guosheng Liu and Judith A. Curry

1. Introduction Microwave signals measured from a satelliteborne radiometer can be generally classified into two categories based on how the microwave field interacts with the atmospheric hydrometeors: emission and scattering. At low frequencies where the scattering of upwelling radiation by ice particles is negligible, the satellite-received radiance over a radiatively cold ocean varies in correspondence to the change in the total amount of liquid hydrometeors in the atmosphere. A higher

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Fuzhong Weng and Quanhua Liu

models although the measurements contain rich information on various weather processes. In the next decade when many advanced microwave and infrared sensors are deployed in space and their sensitivity to various atmospheric and surface parameters are further improved, the uses of cloudy radiances in NWP models will ultimately augment the impacts that have already been demonstrated through the clear radiance assimilation. Currently, the advanced radiative transfer models including scattering and

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