[1] Multiwavelength (MW) Raman lidars have demonstrated their potential to profile particle parameters; however, until now, the physical models used in retrieval algorithms for processing MW lidar data have been predominantly based on the Mie theory. This approach is applicable to the modeling of light scattering by spherically symmetric particles only and does not adequately reproduce the scattering by generally nonspherical desert dust particles. Here we present an algorithm based on a model of randomly oriented spheroids for the inversion of multiwavelength lidar data. The aerosols are modeled as a mixture of two aerosol components: one composed only of spherical and the second composed of nonspherical particles. The nonspherical component is an ensemble of randomly oriented spheroids with size-independent shape distribution. This approach has been integrated into an algorithm retrieving aerosol properties from the observations with a Raman lidar based on a tripled Nd:YAG laser. Such a lidar provides three backscattering coefficients, two extinction coefficients, and the particle depolarization ratio at a single or multiple wavelengths. Simulations were performed for a bimodal particle size distribution typical of desert dust particles. The uncertainty of the retrieved particle surface, volume concentration, and effective radius for 10% measurement errors is estimated to be below 30%. We show that if the effect of particle nonsphericity is not accounted for, the errors in the retrieved aerosol parameters increase notably. The algorithm was tested with experimental data from a Saharan dust outbreak episode, measured with the BASIL multiwavelength Raman lidar in August 2007. The vertical profiles of particle parameters as well as the particle size distributions at different heights were retrieved. It was shown that the algorithm developed provided substantially reasonable results consistent with the available independent information about the observed aerosol event.Citation: Veselovskii, I., O. Dubovik, A. Kolgotin, T. Lapyonok, P. Di Girolamo, D. Summa, D. N. Whiteman, M. Mishchenko, and D. Tanré (2010), Application of randomly oriented spheroids for retrieval of dust particle parameters from multiwavelength lidar measurements,

The UV Raman lidar system (BASIL), operational at University of Basilicata (Potenza-Italy) and capable to perform high-resolution and accurate measurements of atmospheric temperature and water vapour based on the application of the rotational and vibrational Raman lidar techniques in the UV, was recently involved in the LAUNCH 2005 experiment (International Lindenberg campaign for assessment of humidity and cloud profiling systems and its impact on high-resolution modelling) held from 12 September to 31 October 2005. A thorough description of technical characteristics, measurements capabilities and performances of BASIL is given in the paper. Measurements were continuously run between 1 and 3 October 2005, covering a dry stratospheric intrusion episode associated with a tropopause folding event. The measurements in this paper represent the first simultaneous Raman Lidar measurements of atmospheric temperature and water vapour mixing ratio, and consequently relative humidity, reported for an extensive observation period (32 hours). The use of water vapour to trace intruded stratospheric air allows to clearly identify a dry structure (approx. 1 km thick) originated in the stratosphere and descending in the free troposphere down to ~ 3 km. A similar feature is present in the temperature field, with lower temperature values detected within the dry air tongue. Relative humidity measurements reveal values as small as 0.5-1 % within the intruded air. The stratospheric origin of the observed dry layer has been verified by the application of a Lagrangian trajectory model. The subsidence of the intruding heavy dry air may be responsible for the gravity wave activity observed beneath the dry layer. Lidar measurements have been compared with the output of both the PSU/NCAR Mesoscale Model (MM5) and the European Center for Medium range Weather Forecasting (ECMWF) global model. Comparisons in term of water vapour reveal the capability of MM5 to reproduce the dynamical structures associated with the stratospheric intrusion episode and simulate the deep penetration into the troposphere of the dry intruded layer. Moreover, lidar measurements of potential temperature are compared with MM5 output, while potential vorticity from both ECMWF and MM5 is compared with estimates obtained combining MM5 model vorticity and lidar measurements of potential temperature

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The water vapor data measured with airborne and ground-based lidar systems during the International H 2 O Project (IHOP_2002), which took place in the Southern Great Plains during 13 May-25 June 2002 were investigated. So far, the data collected during IHOP_2002 provide the largest set of state-of-the-art water vapor lidar data measured in a field campaign. In this first of two companion papers, intercomparisons between the scanning Raman lidar (SRL) of the National Aeronautics and Space Administration (NASA) Goddard Space Flight Center (GSFC) and two airborne systems are discussed. There are 9 intercomparisons possible between SRL and the differential absorption lidar (DIAL) of Deutsches Zentrum für Luftund Raumfahrt (DLR), while there are 10 intercomparisons between SRL and the Lidar Atmospheric Sensing Experiment (LASE) of the NASA Langley Research Center. Mean biases of (Ϫ0.30 Ϯ 0.25) g kg Ϫ1 or Ϫ4.3% Ϯ 3.2% for SRL compared to DLR DIAL (DLR DIAL drier) and (0.16 Ϯ 0.31) g kg Ϫ1 or 5.3% Ϯ 5.1% for SRL compared to LASE (LASE wetter) in the height range of 1.3-3.8 km above sea level (450-2950 m above ground level at the SRL site) were found. Putting equal weight on the data reliability of the three instruments, these results yield relative bias values of Ϫ4.6%, Ϫ0.4%, and ϩ5.0% for DLR DIAL, SRL, and LASE, respectively. Furthermore, measurements of the Snow White (SW) chilled-mirror hygrometer radiosonde were compared with lidar data. For the four comparisons possible between SW radiosondes and SRL, an overall bias of (Ϫ0.27 Ϯ 0.30) g kg Ϫ1 or Ϫ3.2% Ϯ 4.5% of SW compared to SRL (SW drier) again for 1.3-3.8 km above sea level was found. Because it is a challenging effort to reach an accuracy of humidity measurements down to the ϳ5% level, the overall results are very satisfactory and confirm the high and stable performance of the instruments and the low noise errors of each profile.

ABSTRACT:The physical forward/inverse scheme ϕ-IASI has been applied to the retrieval of atmospheric vertical profiles of temperature, water vapour and ozone by inverting high spectral infrared observations recorded by the NAST-I Fourier Transform Spectrometer. For the retrieval exercise we have used clear-sky spectra recorded over the sea surface on the night of 9-10 September 2004, during the Italian phase of the EAQUATE field campaign. During the campaign NAST-I flew on board the NASA Proteus aircraft at an altitude of 15 km. Retrievals have been compared to radiosonde observations, profiles from the ECMWF analysis and AIRS level 2 products. While providing a basis for the validation of the ϕ-IASI inversion scheme, the retrieval exercise has also demonstrated (i) the NAST-I ability to accurately detect H 2 O fine-scale vertical features, and (ii) the good quality of the temperature and water vapour profiles from the ECMWF analysis.

[1] This paper presents the project Earth Cooling by Water Vapor Radiation, an observational programme, which aims at developing a database of spectrally resolved far infrared observations, in atmospheric dry conditions, in order to validate radiative transfer models and test the quality of water vapor continuum and line parameters. The project provides the very first set of far-infrared spectral downwelling radiance measurements, in dry atmospheric conditions, which are complemented with Raman Lidar-derived temperature and water vapor profiles. Citation: Bhawar, R., et al. (2008), Spectrally resolved observations of atmospheric emitted radiance in the H 2 O rotation band, Geophys. Res. Lett., 35, L04812,

Abstract.The planetary boundary layer (PBL) includes the portion of the atmosphere which is directly influenced by the presence of the earth's surface. Aerosol particles trapped within the PBL can be used as tracers to study the boundarylayer vertical structure and time variability. As a result of this, elastic backscatter signals collected by lidar systems can be used to determine the height and the internal structure of the PBL.The present analysis considers three different methods to estimate the PBL height. The first method is based on the determination of the first-order derivative of the logarithm of the range-corrected elastic lidar signals. Estimates of the PBL height for specific case studies obtained through this approach are compared with simultaneous estimates from the potential temperature profiles measured by radiosondes launched simultaneously to lidar operation. Additional estimates of the boundary layer height are based on the determination of the first-order derivative of the range-corrected rotational Raman lidar signals. This latter approach results to be successfully applicable also in the afternoon-evening decaying phase of the PBL, when the effectiveness of the approach based on the elastic lidar signals may be compromised or altered by the presence of the residual layer. Results from these different approaches are compared and discussed in the paper, with a specific focus on selected case studies collected by the University of Basilicata Raman lidar system BASIL during the Convective and Orographically-induced Precipitation Study (COPS).