Accession Number : ADA214357

Title :   Optical Measurement of Precipitation.

Descriptive Note : Special rept.,

Corporate Author : COLD REGIONS RESEARCH AND ENGINEERING LAB HANOVER NH

Personal Author(s) : Koh, Gary

Report Date : SEP 1989

Pagination or Media Count : 17

Abstract : A simple optical device is used to measure changes in light intensity caused by precipitating particles as they fall through a beam of light. The intensity changes are analyzed in the amplitude and frequency domains to obtain information about precipitation. Tests conducted in snow and in rain show that the optical device can be used for characterizing precipitation with finer time resolution than conventional methods. Rain rates can be accurately monitored; however, errors in snow rates can be as high as a factor of two. Number flux measurements suggest that periodic trends may exist during snow and rain. Power spectra of the intensity changes show that spectral signatures exist for different types of precipitation. Keywords: Optical measurements; Precipitation; Rain; Snow. (jhd)

Descriptors :   *METEOROLOGICAL INSTRUMENTS, *PRECIPITATION, *RAINFALL INTENSITY, FLUX(RATE), INTENSITY, LIGHT, MEASUREMENT, OPTICAL EQUIPMENT, OPTICAL PROPERTIES, OPTICS, RAIN GAGES, HIGH RESOLUTION, PATTERNS, POWER SPECTRA, RAIN, ACCURACY, RATES, SNOW, SPECTRUM SIGNATURES, LIGHT SCATTERING.

Subject Categories : Meteorology
      Optical Detection and Detectors

Distribution Statement : APPROVED FOR PUBLIC RELEASE