Possibility of hard-target lidar detection of a biogenic volatile organic compound, alpha-pinene gas, over forest areas

The absorption spectrum of alpha -pinene gas, a biogenic volatile organic c ompound, was directly measured with a pulsed mid-infrared laser. The maximu m absorption wavelength was found to be similar to3.42 mum, and an absorpti on cross section of 4.8 x 10(-23) m(2) molec(-1) was obtained. A simple the oretical calculation with the measured spectral data showed that several hu ndreds of parts in 10(12) (ppt) of a-pinene gas in forest-mountain areas ov er a range of similar to 10 km were detectable by a long-path-averaged hard -target absorption lidar. Requirements for system development were also dis cussed. (C) 2001 Optical Society of America.