Study of light attenuation coefficient variation using field measurement in south of Caspian Sea costs (Nowshahr port)

In order to study the means of finding the attenuation coefficient in seawater we performed an experiment by the second harmonic of Nd: YAG laser and diode lasers in plasma physics research center .we measured the passing of the light by power meter in distilled water, and two samples of south Caspian Sea water. This research has been made in all seasons of a year. The absorption attenuation of water sample measure by spectrophotometer. The chalos river discharge, long shore currents, the slop of kapurchal beach, noshahr breakwaters and nearest chalos to the beach are the important factors to increase of sediment and suspended solids and increase of light attenuation coefficient in chalos region. It was found that in both stations green light have the minimum attenuation and maximum penetration while red and infrared wave length have much more attenuation and less than penetration. Also the contamination attenuation coefficient was measured in all seasons of 2010 in two stations. The value of contamination attenuation coefficient in spring for chalos and kapurchal stations higher than other seasons and in winter is lower than. Using fitting method an approximate formula for the coefficient and wavelength was derived.