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  • Author or Editor: J-P. Frangi x
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A. Ben Mohamed and J-P. Frangi

Abstract

This paper presents results of 14 months of ground-based measurements of spectral aerosol optical thickness and horizontal extinction together with related studies such as relations between these parameters, meteorological parameters of the surface and upper air, and total mass load and size distributions, as performed in Niamey, Niger, in West African Sahel.

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A. Ben Mohamed and J-P. Frangi

Abstract

Relationships between the daily values of total precipitable water in the atmosphere and the surface humidity parameters are presented from sunphotometric investigations made daily during the year 1981 and 1982. Turbidity parameters are given in terms of their frequency of occurrence.

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A. Ben Mohamed, J-P. Frangi, J. Fontan, and A. Druilhet

Abstract

Spectral aerosol optical depths were measured in seven localities of Niger (West African Sahel) from February 1986 to June 1987. Results of these observations, together with related climatic parameters, are presented and discussed in this paper.

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A. Druilhet, J. P. Frangi, D. Guedalia, and J. Fontan

Abstract

We present a collection of experimental data concerning turbulent characteristics of the convective boundary layer. These data were obtained by means of instrumented aircraft during numerous experiments carried out above five flight areas from 1973 to 1978. Only dry convective conditions with weak dynamic instability are contained in this report. The computed quantities are vertical turbulent fluxes of sensible and latent heat, second- and third-order moments of vertical wind component, potential temperature and humidity, dissipative and spectral characteristics and length scales. All these quantities are normalized using the convective similarity hypothesis of Deardorff. A particular case is considered for humidity where it is necessary to choose between the two boundary conditions: evaporation and entrainment flux. The latter is chosen.

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