AN AIRBORNE PARTICLE IMAGING NEPHELOMETER FOR MEASURING OPTICAL PHASE FUNCTION

THE OPTICAL PROPERTIES OF CIRRUS CLOUDS REMAIN A MAJOR UNSOLVED COMPONENT IN CLOUD AND CLIMATE RESEARCH (LIOU 1986). THE CURRENT INSTRUMENTATION AVAILABLE FOR IN-SITU MEASUREMENT OF THE SIZE, SHAPE, AND LIGHT-SCATTERINGPROPERTIES OF ICE CRYSTALS IS NOT CAPABLE OF PROVIDING SUFFICIENT INFORMATION TO VERIFY REMOTE MEASUREMENTS (E.G., SATELLITE, AIRBORNE LIDAR, AND RADIOMETERS) OF THE OPTICAL AND RADIATIVE PROPERTIES OF CIRRUS (HEYMSFIELD ET AL. 1990, WIELICKI ET AL. 1990). A NEW INSTRUMENT CAPABLE OF MEASURING THE SIZE, SHAPE, AND OPTICALPHASE FUNCTION OF INDIVIDUAL ICE CRYSTALS IN CIRRUS CLOUDS IS NEEDED. IN PHASE I, THEORETICAL CALCULATIONS AND PROOF-OF-CONCEPT LABORATORY TESTS WILL BE PERFORMED TO VERIFY THE DESIGN OF A PARTICLE-IMAGING NEPHELOMETER. THE NEW INSTRUMENT WILL IMAGE PARTICLES WITH 5-MUM RESOLUTION AND SIMULTANEOUSLY MEASURE THE POLARIZED AND UNPOLARIZED COMPONENTS OF SCATTERED LIGHT IN TWO 180 DEGREES CENTIGRADE ARCS AROUND THE SAMPLE VOLUME. PHASE II WILL SEE THE BUILDING AND TESTING OF AN AIRBORNE VERSION OF THE INSTRUMENT; IT WILL ALSO DEVELOP PARAMETERIZATIONS AND NUMERICAL SIMULATIONS OF THE ENSEMBLE PHASE FUNCTION OF CIRRUS CLOUDS. THE OPTICAL PROPERTIES OF CIRRUS CLOUDS REMAIN A MAJOR UNSOLVED COMPONENT IN CLOUD AND CLIMATE RESEARCH (LIOU 1986). THE CURRENT INSTRUMENTATION AVAILABLE FOR IN-SITU MEASUREMENT OF THE SIZE, SHAPE, AND LIGHT-SCATTERINGPROPERTIES OF ICE CRYSTALS IS NOT CAPABLE OF PROVIDING SUFFICIENT INFORMATION TO VERIFY REMOTE MEASUREMENTS (E.G., SATELLITE, AIRBORNE LIDAR, AND RADIOMETERS) OF THE OPTICAL AND RADIATIVE PROPERTIES OF CIRRUS (HEYMSFIELD ET AL. 1990, WIELICKI ET AL. 1990). A NEW INSTRUMENT CAPABLE OF MEASURING THE SIZE, SHAPE, AND OPTICALPHASE FUNCTION OF INDIVIDUAL ICE CRYSTALS IN CIRRUS CLOUDS IS NEEDED. IN PHASE I, THEORETICAL CALCULATIONS AND PROOF-OF-CONCEPT LABORATORY TESTS WILL BE PERFORMED TO VERIFY THE DESIGN OF A PARTICLE-IMAGING NEPHELOMETER. THE NEW INSTRUMENT WILL IMAGE PARTICLES WITH 5-MUM RESOLUTION AND SIMULTANEOUSLY MEASURE THE POLARIZED AND UNPOLARIZED COMPONENTS OF SCATTERED LIGHT IN TWO 180 DEGREES CENTIGRADE ARCS AROUND THE SAMPLE VOLUME. PHASE II WILL SEE THE BUILDING AND TESTING OF AN AIRBORNE VERSION OF THE INSTRUMENT; IT WILL ALSO DEVELOP PARAMETERIZATIONS AND NUMERICAL SIMULATIONS OF THE ENSEMBLE PHASE FUNCTION OF CIRRUS CLOUDS.