Beam intensity scintillations, characterized by a refractive-index structure parameter and caused by variations of macrometeorological features of the coastal atmosphere such as air temperature, wind speed and direction, and relative humidity, are examined theoretically and experimentally. In our theoretical analysis we present two well-known models considered separately for over-water and over-land atmospheric optical communication or imaging channels. By means of comparison with our experiments carried out in midland coastal environments in southern and northern Israel, we show the limitations of the models to predict the refractive-index structure Cn2 parameter for both daytime and nighttime turbulent atmospheres in different coastal zone meteorological conditions. We also present an extension of an existing model with two different practical applications that, as is shown experimentally, can be a good predictor of Cn2 for optical atmospheric paths over midland coastal zones.
Recently several investigators proposed an extension of the Navy Aerosol Model (NAM) based on analysis of an extensive series of measurements at the Irish Atlantic Coast and at the French Mediterranean Coast. This work extends NAM by use of a similar analysis using data collected at three different Middle East Coastal areas: the Negev Desert (Eilat) Red Sea Coast, the Sea of Galilee (Tiberias) Coast, and the Mediterranean (Haifa) Coast. Results of the aerosol size distribution are compared with those obtained through measurements carried out over the Atlantic Ocean and Mediterranean Coasts. An analysis of these different results allows a better understanding of the similarities and differences between different coastal and open ocean zones. Parameterization is introduced. The aerosol particle concentrations and their dependences on wind speed for these coastal zones are analyzed and discussed.
The behavior of a spatial double pendulum (SDP), comprising two pendulums that swing in different planes, was investigated. Movement equations (i.e., mathematical model) were derived for this SDP, and oscillations of the system were computed and compared with experimental results. Matlab computer programs were used for solving the nonlinear differential equations by the Runge-Kutta method. Fourier transformation was used to obtain the frequency spectra for analyses of the oscillations of the two pendulums. Solutions for free oscillations of the pendulums and graphic descriptions of changes in the frequency spectra were used for the dynamic investigation of the pendulums for different initial conditions of motion. The value of the friction constant was estimated experimentally and incorporated into the equations of motion of the pendulums. This step facilitated the comparison between the computed and measured oscillations.
Various experiments have been carried out recently in Middle East (Israel) environments for prediction of aerosol particle concentration and size distribution versus sea-breeze wind speeds and overland ranges. During these experiments aerosol particle concentrations for different overland distances were measured and analyzed. This work proposes a new model for aerosol size distribution prediction up to 50-km distance away from the Mediterranean coast based on an extensive series of measurements. The model introduces coefficients and characteristics of processes of absorption and scattering by aerosol particles in the northern Negev desert areas. Effects of sea breeze wind over different ranges are described by the model proposed in this work using parameters obtained empirically.
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