This PDF file contains the front matter associated with SPIE Proceedings Volume 7479, including the Title Page, Copyright information, Table of Contents, and the Conference Committee listing.

Vertically resolved profiles of optical properties of aerosols were measured using a multi-wavelength lidar system-RALI, set up at the scientific research center in Magurele, Bucharest area (44.35 N latitude, 26.03 E longitude) during 2008. The use of multiple laser wavelengths has enabled us to observe significant variations in backscatter profiles depending on the particle origins. An air mass backward trajectory analysis, using Hysplit-4, was carried out to track the aerosol plumes. Aerosols can serve as valuable tracers of air motion in the planetary boundary layer (PBL). The height of layers in the lower troposphere from lidar signal was calculated using the gradient method- minima of the first derivative. The Richardson number method was used to estimate PBL height from the radio-soundings. We have used pressure, temperature and dew point profiles as well as the wind direction profiles from NOAA (National Oceanic and Atmospheric Administration) data base. The results were consistent with the ones obtained from LIDAR.

Results of measurements of atmospheric aerosol performed with multiwavelength lidar are presented. An approach to retrieve profiles of aerosol particle size distribution was elaborated. It consists in direct fit of predefined distribution (usually combination of lognormal functions with a few free parameters) to the experimental signals. The approach was used for retrieving marine aerosol distributions. Studies of behavior of the particles at the cumulus cloud base were performed as well. There the assumptions based on Twomey's model of the adiabatic parcel were used to support the retrieving technique which was adopted to analyze lidar profiles (at 355, 532 and 1064 nm wavelengths) registered in the region of the base of small warm cumulus clouds. Size distribution profiles and changes of particle effective radius within the range of 0.5 - 3 μm were discussed.

Duststorms and sandstorms regularly devastate Northeast Asia and cause considerable damage to transportation system and public health; further, these events are conceived to be one of the very important indices for estimating the global warming and desertification. Previously, yellow sand events were considered natural phenomena that originate in deserts and arid areas. However, the greater scale and frequency of these events in recent years are considered to be the result of human activities such as overgrazing and over-cultivation. Japan, Korea, Cina and Mongolia are directly concerned to prevent and control these storms and have been able to some extent to provide forecasts and early warnings. In this framework, to improve the accuracy of forecasting , a compact and rugged eye safe lidar, the EZ LIDA^TM, developed together by Laboratoire des Sciences du Climat et l'Environnement (LSCE) (CEA-CNRS) and LEOSPHERE (France) to study and investigate structural and optical properties of clouds and aerosols, thanks to the strong know-how of CEA and CNRS in the field of air quality measurements and cloud observation and analysis, was deployed in Seoul, Korea in order to detect and study yellow sand events, thanks to its depolarization channel and scan capabilities. The preliminary results, showed in this paper, of this measurement campaign put in evidence that EZ Lidar, for its capabilities of operating unattended day and night under each atmospheric condition, is mature to be deployed in a global network to study long-range transport, crucial in the forecasting model.

Nowadays there is an increasing concern about the direct and indirect influence of the aerosols in the Earth's radiative budget. Aerosols from biomass burning activities have been identified as a significant radiative forcing agent. A significant concentration quantity of aerosol particles observed in the atmosphere can be associated with intense anthropogenic biomass burning activity. The CALIPSO satellite and ground-based Lidar systems are indispensable to provide the vertical structure and optical properties of aerosol and clouds on global and local scale, respectively. The Brazilian mid-western region is one of the biggest producers of biomass burning in the whole continent. Aerosols from biomass burning can be transported to distances of hundreds or thousands of kilometers. It has been developed a computational routine to map the CALIPSO overpasses over the whole country in order to retrieve the total coverage taking special attention in the Brazilian AERONET sites. In this context, the measured data from AERONET, CALIPSO and MODIS Satellite and the MSP-Lidar system from Instituto de Pesquisas Energéticas e Nucleares (IPEN) can be used to map the aerosols biomass burning plumes transported from the mid-western to the southeastern region. In total 5 sites were chosen spanning from 0 to 23 South latitude and 46 to 60 West in longitude in coverage during 2007 and we were able to identify such transports during the months of August and September.

To provide reasonable forcasts of near surface PM2.5 levels, it necessary that satellite measurments provide a reasonable estimator of PM2.5 which can be coupled to a transport model. Unfortunately this requires that the aerosol be homogeneously mixed and that the extent of the PBL be sufficiently accurate. For example, the IDEA product (Infusing satellite Data into Environmental Applications) used by the EPA relies on a static relationship connecting PM2.5 to MODIS aerosol optical depth (AOD) which relies on a static model of the PBL aerosol height. In this paper, we show that the PBL height is far from static and by taking the variable PBL into account, a better prediction of PM2.5 from the MODIS (AOD) measurements is obtained. In addition, seasonal variations in the microphysical properties are also demonstrated and accounting for the additional variability further improves the PM25/AOD slope predictor.

Principal Component Analysis (PCA) has proven to be a valuable tool for remote sensing data compression, pattern recognition, and for filtering out measurement noise. In this paper, we present preliminary results on the application of PCA technique to reduce random noise present in lidar observations. Typically, the SNR at a given range can be improved either by increasing the integration time of the measurements or by applying spatial averaging. This procedure, however, improves the SNR at the expense of the instrument's temporal and spatial resolution. The number of range bins needed to characterize backscatter features is far less than the number of components needed to characterize the distribution of these features in the atmosphere. The higher-order PCA components, which mainly serve to characterize noise, can be eliminated along with the noise that they characterize. The results of PCA noise filtering of lidar observations strongly depend on the variability of aerosol plumes. To avoid loss of information in the presence of highly variable aerosol plumes, it is necessary to use a conservative number of principal components higher then optimum for maximum noise reduction. Nevertheless, noise reduction factors of 2-8, depending on the lidar range and atmospheric variability, can still be achieved.

This work suggests the use of a method to retrieve atmospheric information such as the aerosol backscatter and extinction coefficients from a elastic backscatter LIDAR observations. This approach inverts the lidar equation via an optimal estimation method. In order to get satisfactory inversion results, some boundary and measurements conditions can be estimated concomitantly instead of being assumed a priori. This method based on a Bayesian inference together with a Gaussian statistic creates an algorithm where the most probable or optimal solution corresponds to maximize probability density function as a condition to the estimate of the lidar data profile. This application to lidar data analysis presents advantages such as: 1) the possibility of incorporating multiple heterogeneous sources, such as an additional wavelength for instance or aerosol optical thickness information from AERONET (NASA Aerosol Robotic Network) as additional information; 2) the analyzed data can vary over the irradiated region or time. For example, the atmosphere during the daytime presents different characteristics from the nighttime. The algorithm can process different kinds and amounts of information; 3) the error estimation can be retrieved separately by each uncertainty source (errors), such as the model assumptions and a priori errors statements. Yet, it allows clearer and more confident measurements.

Lidar techniques represent the most suitable tool to obtain information on the aerosol vertical distribution and therefore to close this kind of observational gap. Lidar networks are fundamental to study aerosol on large spatial scale and to investigate transport and modification phenomena. These are the motivations why EARLINET, the European Aerosol Research Lidar Network, was established in 2000. At present, EARLINET consists of 25 lidar stations: 7 single backscatter lidar stations, 9 Raman lidar stations with the UV Raman channel for independent measurements of aerosol extinction and backscatter, and 9 multiwavelength Raman lidar stations (elastic channel at 1064 nm, 532 nm, 355 nm, Raman channels at 532 nm and 355 nm, plus depolarization channel at 532 nm) for the retrieval of aerosol microphysical properties. EARLINET data can significantly contribute to the quantification of aerosol concentrations, radiative properties, long-range transport and budget, and prediction of future trends on European and global scale. It can also contribute to improve model treatment on a wide range of scales and to a better exploitation of present and future satellite data. EARLINET is playing an important role in the validation and in the full exploitation of the CALIPSO mission. EARLINET started correlative measurements for CALIPSO since June 2006. A strategy for correlative measurements has been defined on the base of the analysis of the high resolution ground track data provided by NASA. Results in terms of comparisons between EARLINET and available CALIPSO products, both level 1 and level 2 data, are presented.

Coordinated lidar observations of Saharan dust over Europe are performed in the frame of the EARLINET-ASOS (2006-2011) project, which comprises 25 stations: 16 Raman lidar stations, including 8 multi-wavelength (3+2 station) Raman lidar stations, are used to retrieve the aerosol microphysical properties. Since the launch of CALIOP, the two-wavelength lidar on board the CALIPSO satellite (June 2006) our lidar network has been performing correlative aerosol measurements during CALIPSO overpasses over the individual stations. In our presentation, we report on the correlative measurements obtained during Saharan dust intrusions in the period from June 2006 to June 2008. We found that the number of dust events is generally greatest in late spring, summer and early autumn periods, mainly in southern and south-eastern Europe. A measurement example is presented that was analyzed to show the potential of a ground based lidar network to follow a dust event over a specific study area, in correlation with the CALIOP measurements. The dust transport over the studied area was simulated by the DREAM forecast model. Cross-section analyses of CALIOP over the study area were used to assess the model performance for describing and forecasting the vertical and horizontal distribution of the dust field over the Mediterranean. Our preliminary results can be used to reveal the importance of the synergy between the CALIOP measurement and the dust model, assisted by ground-based lidars, for clarifying the overall transport of dust over the European continent.

Routine lidar measurements of the aerosol vertical distribution have been performed over Athens, Greece using a multi-wavelength (355-387-407-532-607-1064 nm) Raman lidar system, since 2006 in the frame of the EARLINET-ASOS (2006-2011) project. Additionally, since June 2006, correlative measurements for CALIOP space-borne lidar are performed. The aim of these measurements is to provide validation profiles for the CALIOP instrument in the lower and middle troposphere (0.5-8 km) in terms of the aerosol backscatter coefficients at 532 nm and 1064 nm, the color ratio (532/1064 nm) and the depolarization ratio at 532 nm, but mainly to provide information about the aerosol extinction profiles and the corresponding lidar ratios at 532 nm. From the available correlative CALIOP level-2 and multi-wavelength Raman lidar aerosol data over Athens, we selected to present cases that have been identified as Saharan dust outbreaks and large biomass burning events, using air mass backward trajectories in order to characterize the source of the aerosols. We found that the vertical profiles of the aerosol optical properties between CALIOP and NTUA lidars were not always in a good agreement during the exact time of the satellite overpass, especially for daytime measurements, when the distance between the two instruments was greater than 40 km. An improvement was noticed when ground-based lidar measurements where performed previously or later than the CALIPSO overpass time. For the nighttime intercomparison the agreement between the two instruments was better during the CALIPSO overpass time. This was attributed mainly to the closer nighttime satellite track over the Athens lidar station.

A-SCOPE (Advanced Space Carbon and Climate Observation of Planet Earth) has been one of the six candidates for the third cycle of the Earth Explorer Core missions, selected by the European Space Agency (ESA) for assessment studies. Earth Explorer missions focus on the science and research aspects of ESA's Living Planet Programme. A-SCOPE mission aims at observing atmospheric CO₂ for a better understanding of the carbon cycle. Knowledge about the spatial distribution of sources and sinks of CO₂ with unprecedented accuracy will provide urgently needed information about the global carbon cycle. A-SCOPE mission encompasses a new approach to observe the Earth from space based on an IPDA (Integrated Path Differential Absorption) Lidar. Based on the known principle of a differential measurement technique, the IPDA lidar relies on the measurement of the laser echoes reflected by hard targets as the ground or the top of the vegetation. Such a time-gated technique is a promising way to overcome the sources of systematic errors inherent to passive missions. To be fully exploited, it however translates into stringent instrument requirements and requires a dedicated performance assessment. In this paper, the A-SCOPE instrument concept is first presented, with the aim of summarizing some important outcomes from the industrial assessment studies. After a discussion of the mission requirements and measurement principles, an overview is given about the instrument architecture. Then the instrument performance is reported, together with a detailed discussion about sources of systematic errors, which pose the strongest technical challenges.

A new lidar instrument, dubbed AeRO (Aerosol Raman Ozone) Lidar, is being developed at Environment Canada's Centre For Atmospheric Research Experiments (CARE). The new system will use three lasers to simultaneously measure ozone, water vapour and aerosol profiles (including extinction) from near ground to the tropopause. The main thrust will focus on understanding Air Quality within the airshed with the capability of looking at Stratospheric Tropospheric Exchange (STE) processes to determine the magnitude and frequency of such events leading to elevated levels of tropospheric ozone. In addition a wind profiler through a partnership with University of Western Ontario will soon be deployed to CARE to provide complementary observations of the tropopause. The lidar participated in the ARC-IONS field campaign during April and July of 2008. During the field campaign, daily ozonesondes were released to further compliment the lidar measurements. Details of the system design and preliminary results from the lidar measurements will be presented.

We report on a novel 2 μm laser transmitter for CO₂ DIAL, based on a nanosecond parametric master oscillator-power amplifier architecture. The master oscillator is an entangled-cavity, doubly resonant, optical parametric oscillator, based on a type-II periodically poled Lithium Niobate nonlinear crystal. This device provides single-longitudinal-mode radiation, with a high frequency stability and high beam quality, with no need of an additional seeding source. The 2.05 μm signal emission is amplified by multi-stage parametric amplifiers to generate more than 10 mJ. After amplification, both the spectral purity and beam quality are maintained: we demonstrate single-longitudinal-mode emission with a frequency stability better than 3 MHz rms, within a nearly diffraction limited beam, with a M² quality factor close to 1.5. The unique performances of this parametric architecture make this device a relevant transmitter for CO₂ differential-absorption LIDAR. Such approach could be readily duplicated for the detection of other greenhouse gases.

Forest fires can be the cause of environmental catastrophe, with the natural outcomes of serious ecological and economic damages, together with the possibility to endanger human safety. At the aim to reduce this catastrophe several author have been shown that the Laser light scattering can be uses to reveals the particulate emitted in the smoke. Infact experimental and theoretical investigations have shown that lidar is a powerful tool to detect the tenuous smoke plumes produced by forest fires at an early stage. In early 90's Arbolino and Andreucci have shown the theoretical possibility to detect the particulate emitted in atmosphere from smoke forest fire. Vilar at all have shown experimentally the possibility to measure the density variation in atmosphere due to plume emitted in forest fire event. Gaudio at all. have already shown that it is possible to evaluate water vapor emitted in smoke of vegetable fuel using a CO₂ dial system. In this paper a theoretical model to evaluate the capabilities of a lidar system in fire surveillance of wooded areas will be presented. In particular we intend propose a technique to minimizing the false alarm in the detection of forest fire by lidar based on a measurement of second components emitted in a combustion process. Usually to detect a fire alarm a rapid increase of aerosol amount is measured. If the backscattering signal report a peak, the presences of a forest fire will be probable. Our idea to confirm this hypothesis is measure the second components emitted in a forest fire at the aim to minimize the false alarm. The simulated measurements of the humidity amount within the smoke plume will be carried out by means of Raman analysis. Fixing the burning rate of the vegetable-fuels, the maximum range of detection will be evaluated.

We show here new results of a Raman LIDAR calibration methodology effort putting emphasis in the assessment of the cross-section ratio between water vapor and nitrogen by the use of a calibrated NIST traceable tungsten lamp. Therein we give a step by step procedure of how to employ such equipment by means of a mapping/scanning procedure over the receiving optics of a water vapor Raman LIDAR. This methodology has been independently used at Howard University Raman LIDAR and at IPEN Raman LIDAR what strongly supports its reproducibility and points towards an independently calibration methodology to be carried on within an experiment routine.

VisibleWind^TM is developing an inexpensive rapid response system, for accurately characterizing wind shear and small scale wind phenomena in the boundary layer and for prospecting suitable locations for wind power turbines. The ValidWind system can also collect reliable "ground truth" for other remote wind sensors. The system employs small (0.25 m dia.) lightweight balloons and a tracker consisting of an Impulse 200 XL laser rangefinder coupled to a PC for automated data recording. Experiments on balloon trajectories demonstrate that the laser detection of range (± 0.5 m), together with measured azimuth and altitude, is an inexpensive, convenient, and capable alternative to other wind tracking methods. The maximum detection range has been increased to 2200 meters using micro-corner-cube retroreflector tape on balloons. Low power LEDs enable nighttime tracking. To avoid large balloon gyrations about the mean trajectory, we use balloons having low ascent rates and subcritical Reynolds numbers. Trajectory points are typically recorded every 4 - 7 seconds. Atmospheric features observed under conditions of inversions or "light and variable winds" include abrupt onsets of shear at altitudes of 100-250 m, velocity changes of order 1-3 m/s within layers of 10-20 m thickness, and veering of the wind direction by 180 degrees or more as altitude increases from 300 to 500 m. We have previously reported comparisons of balloon-based wind profiles with the output of a co-located sodar. Even with the Impulse rangefinder, our system still requires a "man in the loop" to track the balloon. A future system enhancement will automate balloon tracking, so that laser returns are obtained automatically at 1 Hz. While balloon measurements of large-scale, high altitude wind profiles are well known, this novel measurement system provides high-resolution, real-time characterization of the fluctuating local wind fields at the bottom of the boundary layer where wind power turbines and other remote wind sensors must operate.

The new development of a one-sided nonlinear adaptive shift estimation technique (NADSET) is introduced. The background of the algorithm and a brief overview of NADSET are presented. The new technique is applied to the wind parameter estimates from a 2-μm wavelength coherent Doppler lidar system called VALIDAR located in NASA Langley Research Center in Virginia. The new technique enhances wind parameters such as Doppler shift and power estimates in low Signal-To-Noise-Ratio (SNR) regimes using the estimates in high SNR regimes as the algorithm scans the range bins from low to high altitude. The original NADSET utilizes the statistics in both the lower and the higher range bins to refine the wind parameter estimates in between. The results of the two different approaches of NADSET are compared.

A new conduction cooled compact laser for Laser Induced Breakdown Spectroscopy (LIBS) on Mars is presented. The laser provides pulses with energy higher than 30mJ at 1μm of wavelength with a good spatial quality (M² between 1 and 3 according to the temperature). The performance of the laser is within the specifications on a large temperature range (-20°C/+20°C). This laser will be mounted on the ChemCam Instrument of the NASA mission MSL 2009 (finally reported to 2011). The goal of this instrument is to study the chemical composition of Martian rocks. A laser source (subject of this presentation) emits a pulse. It creates a luminous plasma on the rock, which is then analyzed by three spectrometers. The laser source was developed by the French company Thales Laser, under funding and with technical support from CNES. The laser is compact and does not require any active cooling. More recently, the laser was studied by the LATMOS (Laboratoire Atmosphères, Milieux, Observations Spatiales, former Service d'Aéronomie). The goal of this study was to make spectral measurements on the laser to evaluate its capacity to be used as a luminous source for Lidar applications, and in particular for a Doppler Lidar measuring the wind speed. As the laser is very well adapted to the harsh Martian environments, one of the possible applications would be wind speed measurements on Mars. The first results obtained by the LATMOS are good and do not show any impossibilities for this target application.

To fully understand atmospheric dynamics, climate studies, energy transfer, and weather prediction the wind field is one of the most important atmospheric state variables. Studies indicate that a global determination of the tropospheric wind field to an accuracy of 0.5 m/s is critical for improved numerical weather forecasting. LEOSPHERE recently developed a new generation long range compact, eye safe and transportable wind Lidar, named WLS70, capable to fully determine locally the wind field in real time in the planetary boundary layer (PBL). First results of the measurement campaign put in evidence both wind velocity vertical profiles and atmosphere structure derived from Lidar data.

Long range water vapor DIAL-systems require efficient and rugged laser sources. The quasi-three-level transition from R₁ to Z₅ in Nd:GSAG with 943nm wavelength is a promising candidate. An actively Q-switched Nd:GSAG laser was established. Up to 31mJ output pulse energy and up to 26Hz repetition rate was achieved. Injection seeding was used to obtain single frequency operation. The seed laser is a distributed feedback laser diode. Laser frequency was stabilized by ramp-hold-fire method. By tuning the wavelength of the seed laser a 0.83nm tuning range of the pulsed Nd:GSAG laser was obtained. Measured by Fabry-Perot interferometer the spectral line width was approximately 50MHz.

Measurement of the three-dimensional distribution of atmospheric trace gases, especially CO₂, is an important factor to improve the accuracy of climate models and to understand the global effects of the greenhouse effect. This can be achieved by differential absorption Lidar (DIAL). The absorption spectrum of CO₂ features several suitable absorption lines for a ground-based or air-borne DIAL system working at wavelengths between 1.57 μm and 1.61 μm. An appropriate laser transmitter must emit laser pulses with pulse energies of more than 10 mJ and pulse duration in the nanosecond range. For high spectral purity the bandwidth is required to be less than 60 MHz. OPOs and Er-doped solid-state lasers emit around 1.6 μm, but we describe here alternatively Nd:YAG and Nd:glass laser systems with Raman converters. The use of stimulated Raman scattering in crystalline and ceramic materials is a possibility to shift the wavelength of existing lasers depending on the size of the Raman shift. After the investigation of a large number of Raman-active materials some of them could be identified as promising candidates for the conversion of typical Nd:YAG emission wavelengths, including LiNH₂C₆H₄SO₃•H₂O, Ba(NO₃)₂, Li₂SO₄•H₂O, Y(HCOO)₃•2H₂O, β-BBO and diamond. Our experiments with Ba(NO₃)₂ showed that the choice of the material should not be restricted to those with an adequate first order Stokes Raman line position, but also second or third order Raman shift should be considered. Development of Raman frequency converters for high pulse energies concentrates on linear and folded resonator designs and seeded Raman amplifiers using the Raman material as a direct amplifier. With Ba(NO₃)₂ pulse energy up to 116 mJ and 42 % quantum efficiency at the third Stokes wavelength with 1599 nm has been demonstrated. High power operation at 5 W with compensation of thermal lensing was achieved.

Smoke and dust aerosol plumes are observed by the ground-based multi-wavelength elastic-Raman lidar, sunphotometer and space-borne lidar CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization). Lidar-derived multi-wavelength aerosol extinction profiles and column lidar ratios are constrained by the independently measured optical depths. The aloft smoke plume layers from Idaho/Montana forest fires were measured at 2~8 km altitude by the ground lidar on Aug. 14~15, 2007. High aerosol optical depths (AOD) are shown with the value of 0.6~0.8 at wavelength 500 nm and Angstrom exponent of 1.8. The CALIOP observations generally show consistent plume height distribution with the ground lidar, but partly misclassify these smoke plumes as clouds. The forest fire sources and intra-continental smoke transport are clearly illustrated by CALIOP and MODIS satellite imageries. For the moderate dust-like plumes on April 18, 2008, they were observed at the altitude of 2~6 km. Aerosol optical depths vary from 0.2 to 0.4 at wavelength 500 nm with Angstrom exponent <1.0 in the plume-layer. Ground-lidar and CALIOP retrievals show the good agreement in dust-like layer heights, extinction profiles and aerosol species classification.

Lidar calibration at the 1064-nm channel is explored by using the low-level water-phase cloud and high cirrus cloud. Based on a known constant of lidar ratio in the optically thick water cloud, the lidar calibration constant is estimated by integrating lidar returns in the cloud. By using wavelength independence of cirrus cloud backscatter, the lidar constant is analyzed with the two-wavelength signals ratio at 532-nm and 1064-nm after correcting aerosol transmittance from sunphotometer measurement. Calibration constants by these two separate methods are compared on the same day and show consistency with the relative difference of less than 30% in general. We further verify the calibration constant by regressing lidar signals with calibrated ceilometer data in the low planetary boundary layer (PBL). Moreover, the calibration result is tested by applying it to estimate aerosol backscatter at 1064-nm and Angstrom exponent. In the end, normalized daily averages of lidar constants over two-month period are presented.