CREST LIDAR Network
CREST LIDAR Network (NY,VA,MD,PR) studies the vertical profiling along the Atlantic Coast transect from NYC to Caribbean with applications to aerosol transport and air quality. It has been cooperated in founding the International GAW Aerosol LIDAR Observation Network. Lidar is an acronym for LIght Detection And Ranging, a technique similar in principle to Sonar and Radar to determine ranging, or the measurement of distance by time domain reflections. Lidar uses a (often pulsed) beam source while measuring the time and intensity of reflected energy. When there is no ‘solid’ target, there is still a small portion of the beam that is reflected by atmospheric constituents along the line of sight (backscatter.) This measurement technique can infer several characteristics of the target or also of the intervening atmosphere.
The processed return signal or echo can be used to develop 2 and 3 dimensional plots, and has numerous applied uses:
- Backscatter Lidar (e.g our lidar data of aerosol vertical concentration versus time in the earth’s atmosphere.)
- Raman Lidar (Light scattering by molecules where the wavelength is changed by the scattering. The change in wavelength depends on the temperature of the air and the type of molecule from which the scattering takes place. This can be used, for example, to determine the water vapor concentration in the upper atmosphere.)
- Cirrus Cloud Lidar (e.g. The depolarization ratio of backscattered light is being used to study the structure and dynamics of cirrus clouds.)
- DIAL Lidar (DIfferential Absorbtion Lidar using two wavelengths to determine atmospheric component concentrations by subtraction, e.g ozone.)
- Doppler Lidar (e.g. Velocity measurement and display of area turbulent winds.)
- Ranging Lidar (Similar to Radar, e.g. vertical mapping of the the New York City World Trade Center Twin Towers 9/11 site.)
