CO[sub 2] lidar technique for observing characteristic drop size in water clouds

Journal Article · Fri Jan 01 00:00:00 EST 1993 · IEEE Transactions on Geoscience and Remote Sensing (Institute of Electrical and Electronics Engineers); (United States)

DOI:https://doi.org/10.1109/36.210444· OSTI ID:6440017

Eberhard, W L ^[1]

---

1. NOAA, Boulder, CO (United States)

An analytical evaluation demonstrates that a calibrated 10.6-[mu]-wavelength lidar can measure the mean radius and the effective radius of the drop size distribution in a water cloud. The radius parameter observed is a weighted average over the penetration depth of the pulse, with weighting factor decreasing with optical depth. In this method, the lidar signal is integrated and boundary conditions on optical depth are applied to obtain the average extinction-to-backscatter ratio. The radius parameter is determined by comparing the measured ratio with that found from Mie scatter calculations for a variety of typical drop size distributions. This extinction-to-backscatter method was originally proposed in the literature for measuring mode radius, but at 10.6-[mu]m wavelength the current results show better accuracy for mean or effective radius. Other CO[sub 2] laser wavelengths can be used, but slightly more stable results are expected at longer wavelengths. sources of error are discussed. A lidar probed the sides of fair-weather cumulus clouds in the first application of this method. The resulting values of effective radius were reasonable, and the expected increase of effective radius with height was observed.

• DOE Contract Number: FG02-90ER61059
• OSTI ID: 6440017
• Journal Information: IEEE Transactions on Geoscience and Remote Sensing (Institute of Electrical and Electronics Engineers); (United States), Vol. 31:1; ISSN 0196-2892
• Country of Publication: United States
• Language: English

Related Subjects

47 OTHER INSTRUMENTATION
54 ENVIRONMENTAL SCIENCES
CLOUDS
REMOTE SENSING
OPTICAL RADAR
SENSITIVITY
SPECIFICATIONS
WEATHER
FORECASTING
BACKSCATTERING
CALCULATION METHODS
CARBON DIOXIDE
CLOUD COVER
DIMENSIONS
DROPLETS
MOISTURE
PARTICLE SIZE
RAIN
WATER
ATMOSPHERIC PRECIPITATIONS
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
HYDROGEN COMPOUNDS
MEASURING INSTRUMENTS
OXIDES
OXYGEN COMPOUNDS
PARTICLES
RADAR
RANGE FINDERS
SCATTERING
SIZE
440700* - Geophysical & Meteorological Instrumentation- (1990-)
540150 - Environment
Atmospheric- Site Resources & Use Studies- (1990-)