Underwater Illumination Research Articles

網走湖に於ける水中光度の日週變化

網走湖に於ける水中光度の日週變化

Submarine Illumination in Photometric Units

The paper describes a method of obtaining underwater illumination in photometric units. The results are given as total horizontal illumination at different depths and as cell current extinction coefficients of two bands in the visible spectrum. The effect of temperature on the submerged photometer is indicated, and a mean temperature coefficient between 0°C and 17°C is calculated.

The Ecology of the Tamar Estuary V. Under-Water Illumination. Revision of Data for Red Light

New values for the extinction coefficient of red light in distilled water require that published results for this coefficient in waters from the Tamar Estuary shall be increased by o.1, 1.3 and 2.0 at 610, 720 and 750 mμ respectively. Earlier deductions as to the favourable transmission of red light in turbid estuarine waters apply only up to about 680 mμ. That part of the extinction coefficient due to suspensoids and colouring matter was inversely proportional to the first power of the wave-length. Other conclusions remain unaffected.

The Ecology of the Tamar Estuary II. Under-Water Illumination

The Zeiss Pulfrich photometer, with its eight spectral niters covering narrow spectral bands within the visible spectrum, has been used to investigate the penetration of light into an estuary under winter and summer conditions.Throughout the visible spectrum, extinction coefficients in Hamoaze are always higher, in winter often very much higher, than in the English Channel. In marked contrast to the open sea, red light penetrates as well or better than green, and blue is cut down most rapidly

湖水の水中光度と透明度との関係

1. Measurements of the under-water illumination were made in eight lakes by employing Mazda selenium rectifier photo-electric cell and an unipivot pointer galvanometer.2. Within the limit from 5 to 12 m. in transparency, the illumi-nation at the depth at which the SFCCHI'S disc was just visible was 12.5-18.5% of that at the depth of 1 cm. below the surface, the mean of which was 14.5%.3. The following relation was observed between the transparency (t) and the absorption coefficient (k) of water per meter: t=1.9/k

Apparatus for the Photo-Electric Measurement of Submarine Illumination assembled for the U.S.A. Research Ship Atlantis

Shelford and Gail (1922) first used photo-electric cells for submarine photometry in the Puget Sound. Poole (1925) produced an apparatus which was suitable for use on small ships in the open sea. This apparatus was used near Plymouth by Poole and Atkins (1926, 1928, 1929) with various minor alterations in design which rendered it more reliable and less subject to errors due to electrical leakage. The object of these researches was to study illumination in relation to photosynthesis, but Russell perceived their bearing on his own work on the phototropic movements of the zooplankton. When considering the research programme of the Atlantis, Dr. George L. Clarke decided that it would be of value to carry out photo-electric measurements of submarine illuminations in connection with his work on vertical distribution of the plankton. A request was accordingly made by Dr. H. B. Bigelow, Director of the Wood's Hole Oceanographic Institute, that such an apparatus should be assembled under our direction. The apparatus here described has been constructed closely upon the lines of H. H. Poole's original apparatus as modified in 1928. Special attention, however, has been given to the elimination of electrical leakage. Furthermore, J. H. J. Poole (1928) devised an apparatus in which rate of flash of a neon lamp was used to measure light. This rate of flash method is one of integration and not an instantaneous measurement as is that of H. H. Poole. The value of the neon lamp method lies in the fact that light under the water is extremely variable near the surface owing to the motion of the waves. This method of measuring under-water illumination was used in Lough Bray, Co. Dublin, by J. H. J. and H. H. Poole (1930), and has since been used at sea by Poole and Atkins (1931). It seemed advisable to include a neon lamp photometer in the outfit so that errors in determining the loss of light on entering the water might be minimised.