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P. KRISHNA RAO, W. L. SMITH, and R. KOFFLER

Abstract

A composite histogram method is used to objectively derive sea-surface temperature distribution from satellite radiation measurements for the Northern and Southern Hemispheres. Comparisons with conventional observations yield root-mean-square differences of 2°–3°K. Some of the differences can be accounted for by factors such as the coherent noise introduced by the onboard tape recorder, insufficient atmospheric attenuation corrections, and basic differences between the two types of temperature measurements.

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R. KOFFLER, A. G. DeCOTIIS, and P. KRISHNA RAO

Abstract

A simple objective technique is presented that integrates satellite-measured infrared radiation temperatures with the National Meteorological Center objective temperature analysis to yield cloud height and amount classification for small grid squares. Sample of cloud information obtained by this technique from ITOS 1 data over the United States show good agreement with cloud observations obtained by surface observers and from aircraft reports. The method is completely automated and can be used to produce cloud analyses on a global scale.

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W. L. SMITH, P. K. RAO, R. KOFFLER, and W. R. CURTIS

Abstract

A statistical histogram method is developed to objectively determine sea-surface temperature from satellite high resolution window radiation measurements. The method involves inferring the distribution of surface radiances for the clear atmospheric case from observed histograms of generally cloud-contaminated radiances. The brightness temperature associated with the clear atmosphere modal peak radiance is the statistically most probable surface temperature. The reliability of the inferred surface temperature depends upon the number of cloud-free measurements available to define the clear mode. The method accounts for atmospheric attenuation and instrumental noise and also objectively discriminates cloud-free from cloud-contaminated observations.

The statistical histogram method is applied to 3.8 micrometer window radiation data obtained by the High Resolution Infrared Radiometer flown on the Nimbus 2 and Nimbus 3 satellites. Examples of sea temperatures inferred over both small and large areas are presented. Comparisons with conventional ship observations indicate that both bias and random errors of the inferred sea temperatures are less than 1°C.

Due to the apparent success of this statistical histogram technique, plans have been made to use it to obtain sea-surface temperatures on a global basis daily from operational high resolution infrared radiation measurements.

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I. Ruff, R. Koffler, S. Fritz, J. S. Winston, and P. K. Rao

Abstract

The pattern of reflection of solar radiation from clouds as a function of angle is obtained by statistical analysis of observations from the TIROS IV visible radiation channel (0.55–0.75 μ). Readings from the water-vapor window channel (8ndash;12 μ) were used to select cases in which clouds fill the field of view of the sensor. The results show a generally anisotropic reflection pattern, which varies with solar zenith angle. The anisotropy is greatest for large values of solar zenith angle, the main feature in these cases being high intensity values of the radiation reflected at azimuths close to 180° from the sun, and at large zenith angles.

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