Comparative study of lidars for measuring atmospheric temperature and wind.

The uncertainty of lidar measured atmospheric temperature T or line-of-sight (LOS) wind V is inversely proportional to the signal-to-noise ratio (SNR) of the received photocounts. We term the proportionality constant, which depicts the efficacy of the measurement method, the single-photon (or unity SNR) measurement uncertainty for T and/or V measurement. In this study, we use the single-photon measurement uncertainty as the figure of merit to compare and understand the practical differences between Cabannes scattering (CS), Rayleigh inversion (RI), rotational Raman (RR), and laser induced fluorescence (LIF) lidars for atmospheric temperature and wind measurements, and to optimize the choice and receiver design of a lidar system for a potential application.

Atomic vapor filter revisited: a Cabannes scattering temperature/wind lidar at 770†nm.

Using an atomic/molecular vapor as an aerosol blocking filter for atmospheric temperature measurements with a Cabannes lidar is revisited. Different problems in previously used barium and iodine filters prevented them from delivering the 78 times signal advantage (8.8 times less uncertainty) over rotational Raman lidar. We conclude that, despite the sensitivity optimization in rotational Raman lidar, a proposed Cabannes lidar utilizing potassium vapor filters can have 6.1 times less temperature uncertainty. By tuning the laser frequency cyclically to above and below the potassium D1 transition, the lidar system can measure temperature and wind simultaneously.

Retrieving mesopause temperature and line-of-sight wind from full-diurnal-cycle Na lidar observations.

Narrowband Na lidar measurement of mesopause region temperatures were pioneered by Fricke and von Zahn in 1985, in 1990 by She et al. at Colorado State University (CSU), with upgrades to measure both temperature and wind in 1994, and under sunlit conditions in 1996 with 24 h continuous observational capability in 2002. This paper details the assumptions and procedures for the retrieval of mesopause region temperatures, line-of-sight winds, and sodium densities from day and night signals from the CSU narrowband Na lidar. The Hanle effect and the effect of the pulsed laser line shape function on the accuracy of temperature and LOS wind retrieval are also discussed.

Wind-bias correction method for narrowband sodium Doppler lidars using iodine absorption spectroscopy.

We present a technique to measure the frequency chirp introduced by the laser pulse amplification process in the transmitter of the Colorado State University sodium lidar system. This chirp causes a systematic radial wind bias that must be removed from the reported wind measurements. An iodine absorption line located near the lidar operating wavelength of 589.16 nm is used for real-time monitoring and measurement of the chirp for the correction of radial wind bias. This technique has been thoroughly characterized in the laboratory and validated by field testing, facilitating simultaneous measurements of temperature and horizontal wind in the mesopause region of the atmosphere (80-105 km).