Temperature sensitivity of differential absorption lidar measurements of water vapor in the 720-nm region

Applied Optics (Impact Factor: 1.78). 04/1991; 30(12):1517-24. DOI: 10.1364/AO.30.001517
Source: PubMed


Recently measured properties of water vapor (H(2)O) absorption lines have been used in calculations to evaluate the temperature sensitivity of differential absorption lidar (DIAL) H(2)O measurements. This paper estimates the temperature sensitivity of H(2)O lines in the 717-733-nm region for both H(2)O mixing ratio and number density measurements, and discusses the influence of the H(2)O line ground state energies E'', the H(2)O absorption linewidths, the linewidth temperature dependence parameter, and the atmospheric temperature and pressure variations with altitude and location on the temperature sensitivity calculations. Line parameters and temperature sensitivity calculations for sixty-seven H(2)O lines in the 720-nm band are given which can be directly used in field experiments. Water vapor lines with E'' values in the 100-300-cm(-1) range were found to be optimum for DIAL measurements of H(2)O number densities, while E'' values in the 250-500-cm(-1) range were found to be optimum for H(2)O mixing ratio measurements.

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    • "The evaluation of the temperature sensitivities of water vapor absorption lines in the 820–840-nm spectral region were studied using the methods presented by Browell et al. (1991), leading to the selection of this water vapor absorption line for number density profiles at 828.187 nm (vacuum) (the online wavelength). A summary of the water vapor DIAL transmitter and the receiver specifications are shown in Table 2, where the laser transmitter requirements for accurate water vapor profiling are also shown for comparison. "
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    Journal of Atmospheric and Oceanic Technology 03/2011; 28(3):320-336. DOI:10.1175/2010JTECHA1463.1 · 1.73 Impact Factor
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    • "Our procedure for selecting a water vapor absorption line closely followed the methods of Browell et al., 1991 [41]. Temperature sensitivity analysis involves calculating the error in the absorption cross section with temperature, dσ/dT [cm 2 /K], where σ = KV [cm 2 ], across a range of temperatures, pressures, and ground-state transitional energies, E " [cm -1 ]. "
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    • "). The temperature sensitivity for the number density measurement is calculated using the expression (Browell et al. 1991) "
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    ABSTRACT: A differential absorption lidar (DIAL) instrument for automated profiling of water vapor in the lower troposphere has been designed, tested, and is in routine operation at Montana State University. The laser transmitter for the DIAL instrument uses a widely tunable external cavity diode laser (ECDL) to injection seed two cascaded semiconductor optical amplifiers (SOAs) to produce a laser transmitter that accesses the 824-841-nm spectral range. The DIAL receiver utilizes a 28-cm-diameter Schmidt - Cassegrain telescope; an avalanche photodiode (APD) detector; and a narrowband optical filter to collect, discriminate, and measure the scattered light. A technique of correcting for the wavelength-dependent incident angle upon the narrowband optical filter as a function of range has been developed to allow accurate water vapor profiles to be measured down to 225 m above the surface. Data comparisons using the DIAL instrument and collocated radiosonde measurements are presented demonstrating the capabilities of the DIAL instrument.
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