Atmospheric Test Site Research Articles

Atmospheric effect on the ground-based measurements of broadband surface albedo

Abstract. Ground-based pyranometer measurements of the (clear-sky) broadband surface albedo are affected by the atmospheric conditions (mainly by aerosol particles, water vapour and ozone). A new semi-empirical method for estimating the magnitude of the effect of atmospheric conditions on surface albedo measurements in clear-sky conditions is presented. Global and reflected radiation and/or aerosol optical depth (AOD) at two wavelengths are needed to apply the method. Depending on the aerosol optical depth and the solar zenith angle values, the effect can be as large as 20%. For the cases we tested using data from the Cabauw atmospheric test site in the Netherlands, the atmosphere caused typically up to 5% overestimation of surface albedo with respect to corresponding black-sky surface albedo values.

Environmental degradation of utility power connectors in a harsh environment

This paper reports on an investigation of the effects of a marine atmospheric environment on the performance of aluminum bolted, compression, and fired wedge power connectors. These connector types are representative of the three major connector technologies used in electrical distribution systems throughout the world. The atmospheric test site was situated on the seacoast in Daytona Beach, FL. The test specimens consisted of sections of aluminum and copper conductors joined together by a connector. The paper describes the performance and lifetime of the different connector types exposed to the harsh marine environment. Examinations of failed connectors revealed that failure in all three connector types was ultimately due to galvanic corrosion at the aluminum/copper interfaces within the connectors. The failure rate was largest for compression connections. Bolted connections failed somewhat less rapidly. The failure rate for fired-wedge connections was the lowest.

Unwrapped-phase distribution model for speckle and turbulence

A model for the unwrapped phase of a speckle field that propagates through clear air turbulence is proposed, and a formulation for the probability density function of the unwrapped phase is developed. A method is given to obtain the parameters of the unwrapped density function from parameters of the diffuse target, the laser source, and the atmosphere. Unwrapped-phase measurements at an atmospheric test site with a CO(2) laser show agreement with the model.