Balloon-borne near-infrared diode laser spectroscopy for in situ measurements of atmospheric CH4 and H2O

Absorption spectroscopy with near-infrared telecommunication laser diodes i s a very convenient technique to measure in situ methane and water vapor in both the troposphere and the lower stratosphere (LS) and thereby to addres s many topics in the science of the atmosphere. This technique offers a hig h temporal resolution that ranges from 10 ms to 1 s, a precision error in t he concentration retrieval of within a few percents and a dynamic range for the measurements of four orders of magnitude. A balloon-borne near-infrare d diode laser spectrometer is described that provides simultaneous in situ methane (in the 1.65-mum region) and water vapor (in the 1.39-mum region) m easurements at 1 s intervals. Tropospheric and stratospheric vertical conce ntration profiles of methane and water vapor are reported. (C) 2001 Elsevie r Science B.V. All rights reserved.