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L. P. Stearns

Abstract

The infrared layer temperature change in a cloudy atmosphere normally shows warming at the base of the cloud and intense cooling at the top of the cloud. In a model that uses broad-band radiative transfer to calculate atmospheric temperature changes, errors on the order of 6.0 K day−1 can occur at the top of a cloud if only selected grid points are used. Calculations using grid points at discrete intervals produce a smoothing effect over the entire cooling profile and increase errors. Two case studies were used to demonstrate these problems.

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L. P. Stearns

Abstract

The atmosphere and circulation of air within, above, and around the Grand Canyon of the Colorado River was studied from an instrumented aircraft and from ground-based instruments in September and October 1984. Several patterns were identified. The nighttime formation of stabilized layers and infrared cooling did not necessarily guarantee a downslope and a downstream flow. Morning observations showed early formation of thermal patterns which increased during the day until, under clear skies, turbulent mixing would disrupt the stable layers above the canyon in September. October solar heating seemed insufficient to totally disrupt the stable layers above the canyon, and only limited areal segments displayed instability at the rim level. The depth of the turbulent mixing is a function of sky cover and cloud thickness. The amount of influence of the large-scale air motion depends on the orientation of the canyon relative to the direction of this motion.

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P. M. Kuhn and L. P. Stearns

Abstract

No abstract available.

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P. M. Kuhn and L. P. Stearns

Abstract

A radiometric method for the retrieval of moisture data at altitudes above the radiosonde hygristor cutoff region or in situations where a malfunction of the hygristor occurs is described. The method was applied to BOMEX radiation soundings. Regardless of the exact moisture profile, the method is designed to radiometrically infer the average decrease of moisture through the entire atmospheric column through a solution of the radiative transfer equation. This enables recovery of the total mass of atmospheric water vapor.

In at least 25% of all BOMEX radiometersonde ascents, humidity retrieval did produce a more realistic moisture profile and total mass of precipitable water vapor. In these cases, the radiosonde hygristor humidity deficiencies averaged from −45% at 800 mb to −30% at 600 mb. For such pressure levels, the optical mass of water vapor retrieved for the soundings discussed averaged 1.68 gm cm−2. This represents 56% of the hygristor-measured optical mass. Above 400 mb the optical mass recovered averaged 0.7 gm cm−2 for all BOMEX radiometer soundings. It is suggested that a simple radiometer could be used to improve moisture measurements for soundings requiring the best possible water vapor data.

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P. M. Kuhn and L. P. Stearns

Abstract

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