Comparative study of lidars for measuring atmospheric temperature and wind.

The uncertainty of lidar measured atmospheric temperature or line-of-sight (LOS) wind 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 and/or 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.

Hanle effect in laser-induced fluorescence and Na and Fe resonance scattering lidars.

The nature of the Hanle effect on laser-induced fluorescence (LIF) remains subtle and physically ambiguous. By associating the Hanle effect with the linearly superposed phase-locked excited substates induced by laser-like coherent light, this paper attempts to demystify its underlying physics. The resulting LIF radiation leads to angular distribution of radiation, whose detail depends on the quantum structure of the target atoms.

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.

Mesopause-region temperature and wind measurements with pseudorandom modulation continuous-wave (PMCW) lidar at 589 nm.

A study on the feasibility of using pseudorandom modulation continuous-wave (PMCW) Na lidar for mesopause-region temperature and horizontal wind measurements is presented with a number of specific geometries and associated beam-telescope overlap functions, suitable for ground-based and airborne deployments. The performance of these deployment scenarios is analyzed by scaling from the received signal and sky background and the measurement uncertainties in temperature and horizontal wind of the well-tested Colorado State University pulsed Na lidar. Using currently available high-power (~20 W) continuous-wave Na narrowband lasers, a compact PMCW bistatic Na lidar system can indeed be deployed to simultaneously measure mesopause-region temperature and horizontal winds on a 24 h continuous basis, weather permitting.

Iodine-filter-based high spectral resolution lidar for atmospheric temperature measurements.

This paper presents a method for measuring atmosphere temperature profile using a single iodine filter as frequency discriminator. This high spectral resolution lidar (HSRL) is a system reconfigured with the transmitter of a mobile Doppler wind lidar and with a receiving subsystem redesigned to pass the backscattering optical signal through the iodine cell twice to filter out the aerosol scattering signal and to allow analysis of the molecular scattering spectrum, thus measuring temperatures. We report what are believed to be the first results of vertical temperature profiling from the ground to 16 km altitude by this lidar system (power-aperture product=0.

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.

Direct-detection Doppler wind measurements with a Cabannes-Mie lidar: b. Impact of aerosol variation on iodine vapor filter methods.

Atmospheric line-of-sight (LOS) wind measurement by means of incoherent Cabannes- Mie lidar with three frequency analyzers, two double-edge Fabry-Perot interferometers, one at 1064 nm (IR-FPI) and another at 355 nm (UV-FPI), as well as an iodine vapor filter (IVF) at 532 nm, utilizing either a single absorption edge, single edge (se-IVF), or both absorption edges, double edge (de-IVF), was considered in a companion paper [Appl. Opt. 46, 4434 (2007)], assuming known atmospheric temperature and aerosol mixing ratio, Rb.

Direct-detection Doppler wind measurements with a Cabannes-Mie lidar: a. Comparison between iodine vapor filter and Fabry-Perot interferometer methods.

Atmospheric line-of-sight (LOS) wind measurement by means of incoherent Cabannes-Mie lidar with three frequency analyzers with nearly the same maximum transmission of ~80% that could be fielded at different wavelengths is analytically considered. These frequency analyzers are (a) a double-edge Fabry-Perot interferometer (FPI) at 1064 nm (IR-FPI), (b) a double-edge Fabry-Perot interferometer at 355 nm (UV-FPI), and (c) an iodine vapor filter (IVF) at 532 nm with two different methods, using either one absorption edge, single edge (se-IVF), or both absorption edges, double edge (de-IVF). The effect of the backscattered aerosol mixing ratio, R(b), defined as the ratio of the aerosol volume backscatter coefficient to molecular volume backscatter coefficient, on LOS wind uncertainty is discussed.

Temporal variability of the telluric sodium layer.

The temporal variability of the telluric sodium layer is investigated by analyzing 28 nights of data obtained with the Colorado State University LIDAR experiment. The mean height power spectrum of the sodium layer was found to be well fitted by a power law over the observed range of frequencies, 10 microHz to 4 mHz. The best-fitting power law was found be be 10(beta)nu(alpha), with alpha=-1.

Low-altitude atmospheric wind measurement from the combined Mie and Rayleigh backscattering by Doppler lidar with an iodine filter.

This paper briefly discusses the mobile ground-based incoherent Doppler wind lidar system, with iodine filters as receiving frequency discriminators, developed by the Ocean Remote Sensing Laboratory, Ocean University of Qingdao, China. The presented result of wind profiles in October and November 2000, retrieved from the combined Mie and Rayleigh backscattering, is the first report to our knowledge of wind measurements in the troposphere by such a system, where the required independent measurement of aerosol-scattering ratio can also be performed. A second iodine vapor filter was used to lock the laser to absolute frequency reference for both wind and aerosol-scattering ratio measurements.