This PDF file contains the Front Matter associated with SPIE Proceedings volume 7832, including the Title page, Copyright information, Table of Contents, and Conference Committee listing.

Sustained research efforts at NASA Langley Research Center (LaRC) during last fifteen years have resulted in a significant advancement in 2-micron diode-pumped, solid-state laser transmitter for wind and carbon dioxide measurement from ground, air and space-borne platform. Solid-state 2-micron laser is a key subsystem for a coherent Doppler lidar that measures the horizontal and vertical wind velocities with high precision and resolution. The same laser, after a few modifications, can also be used in a Differential Absorption Lidar (DIAL) system for measuring atmospheric CO2 concentration profiles. Researchers at NASA Langley Research Center have developed a compact, flight capable, high energy, injection seeded, 2-micron laser transmitter for ground and airborne wind and carbon dioxide measurements. It is capable of producing 250 mJ at 10 Hz by an oscillator and one amplifier. This compact laser transmitter was integrated into a mobile trailer based coherent Doppler wind and CO2 DIAL system and was deployed during field measurement campaigns. This paper will give an overview of 2- micron solid-state laser technology development and discuss results from recent ground-based field measurements.

Urbanized cities in the world are exposed to atmospheric pollution events. To understand the chemical and physical processes it is necessary to describe correctly the Planetary Boundary Layer (PBL) dynamics and height evolution. For these proposals, a compact and rugged eye safe UV Lidar, the EZLIDAR™, was developed together by CEA/LMD and LEOSPHERE (France) to study and investigate structural and optical properties of clouds and aerosols and PBL time evolution. A new 2D method of PBL detection, developed by Leosphere and based on image processing, is working on a large set of temporal profiles, typically 6 to 24 hours. It allows the use of the temporal correlation between the profiles and the integration of atmospheric parameters about PBL evolution in the detection algorithms. This method, based on the gradient, is using a unique automatic threshold algorithm that will adapt to any atmospheric conditions. No specific parametrisation is required before measurements and the final result is more robust than a profile per profile method. We validated our algorithm during the two campaigns of the ICOS (Integrated Carbon Observation System) project. These campaigns took place at Trainou (France) on October 2008 and at Mace Head (Ireland) on June 2009 under very different and complicated atmospheric situations, with all different meteorological conditions (frequent showers, windy situations, no significant inversion layer). Furthermore, this algorithm is able to detect accurately clouds and rain episode.

In this paper the numerical simulation results of mean wind velocity vector and its measurement error for VAD technique using Weather Research and Forecasting Model (WRF) and Yamada-Mellor models are presented. The numerical model takes into account the non-Gaussian and nonstationary characteristics of the Doppler lidar signal. The numerical simulation results were compared with CASES-99 experimental data from balloon sonde (GLASS) and the Doppler Lidar. It shows that results of numerical simulation by WRF and Yamada-Mellor models agree well with experimental data for potential temperature. Yamada-Mellor model describes the nocturnal low-level jet only up to 100 m and above the fit is fairly bad. But WRF model allows us to have a good comparison for all levels. In case of the strong turbulence the value of measurement error can greatly surpass the value 0.5 m/s; therefore it does not satisfy World Meteorological Organization (WMO) requirements for wind. For the high spatial resolution we cannot get the required accuracy.

A compact coherent wind lidar system has been developed and is being tested in an urban environment. We use polarization maintaining fiber throughout the system to improve the stability of the heterodyne detected return signal. The 1.54 micron transmitter is designed using a master oscillator and pulsed power amplifier configuration. The receiver is operated in a coaxial arrangement and balanced detection is employed to reduce the effects of relative intensity noise, allowing for operation in the shot noise limited regime. Development and verification of the lidar system is enhanced by taking advantage of a set of ground based sodar, radar wind profiler and building top anemometers that are part of the New York City Meteorological Network. Operation in a coastal urban environment with a complex terrain such as New York City requires that the system be flexible enough to allow for adjustable operating conditions, tunable signal processing algorithms and user defined data products, so that the optimal performance can be chosen with a variety of practical applications in mind.

The ValidWind™ system employs an XL200 laser rangefinder to track small, lightweight, helium-filled balloons (0.33 meters, 0.015 kg). We record their trajectories (range resolution 0.5 meters) and automatically produce local wind profiles in real time. Tracking range is enhanced beyond 2 km by applying retro-reflector tape to the balloons. Aerodynamic analysis shows that ValidWind balloon motion is well coupled to the local wind within relaxation times ~ 1 second, due to drag forces at subcritical Reynolds numbers Re < 2×10⁵. Such balloons are Lagrangian sensors; i.e., they move with the wind as opposed to being fixed in space. In a field campaign involving many balloons, slight variations in ground level winds at launch lead to trajectory patterns that we analyze to derive 3D maps of the vertical and horizontal wind profiles downwind of the launch area. Field campaigns are focused on likely sites for wind power generation and on facilities from which airborne particulates are emitted. We describe results of wind measurements in Utah near the cities of Clarkston, Logan, and Ogden. ValidWind is a relatively inexpensive wind sensor that is easily and rapidly transported and deployed at remote sites. It is an ideal instrument for wind prospecting to support early decisions required, for example, in siting meteorology towers. ValidWind provides high-resolution, real time characterization of the average and changing 3D wind fields in which wind power turbines and other remote sensors must operate.

Aerosols and clouds play important roles in Earth's climate system but uncertainties over their interactions and their effects on the Earth energy budget limit our understanding of the climate system and our ability to model it. The CALIPSO satellite was developed to provide new capabilities to observe aerosol and cloud from space and to reduce these uncertainties. CALIPSO carries the first polarization-sensitive lidar to fly in space, which has now provided a four-year record of global aerosol and cloud profiles. This paper briefly summarizes the status of the CALIPSO mission, describes some of the results from CALIPSO, and presents highlights of recent improvements in data products.

The planetary boundary layer (PBL) heights are derived from the CALIOP/CALIPSO level-1B attenuated backscatter profile using the wavelet transform technique. The results are compared to those by the radiosonde and ground-based lidar coincident measurements. The comparison generally indicates the good agreement and the correlation coefficient is greater than 0.7. In addition, we found the good consistence between the CALIOP-derived PBL height and the selected aerosol-layer-top of CALIPSO level-2 aerosol-layer products (5-km average). Finally, the spatial distribution of PBL heights and their seasonal differences are initially illustrated over the US continent.

We report on a lidar approach to measure atmospheric CO2 column concentration being developed as a candidate for NASA's ASCENDS mission. It uses a pulsed dual-wavelength lidar measurement based on the integrated path differential absorption (IPDA) technique. We demonstrated the approach using the CO₂ measurement from aircraft in July and August 2009 over various locations. The results show clear CO₂ line shape and absorption signals, which follow the expected changes with aircraft altitude from 3 to 13 km. The column absorption measurements show altitude dependence in good agreement with column number density estimates calculated from airborne in-situ measurements. The approaches for O₂ measurements and for scaling the technique to space are discussed.

At the Istituto di Metodologie per l'Analisi Ambientale of the Italian National Research Council (CNR-IMAA) an advanced observatory for the ground-based remote sensing of the atmosphere is operative. This facility is equipped with several instruments including two multi-wavelength Raman lidars, one of which mobile, a microwave profiler, a 36 GHz Doppler polarimetric radar, two laser ceilometers, a sun photometer, a surface radiation station and three radiosounding stations. CNR-IMAA atmospheric observatory (CIAO) is located in Southern Italy on the Apennine mountains (40.60N, 15.72E, 760 m a.s.l.), less than 150 km from the West, South and East coasts. The site is in a valley surrounded by low mountains (<1100 m a.s.l.) and this location offers an optimal opportunity to study different kinds of weather and climate regimes. CIAO represents an optimal site where testing possible synergies between active and passive techniques for improving the profiling capabilities of several atmospheric key variables, such as aerosol, water vapour and clouds, and for the development of an integration strategy for their long-term monitoring. CIAO strategy aims at the combination of observations provided by active and passive sensors for providing advanced retrievals of atmospheric parameters exploiting both the high vertical resolution of active techniques and the typical operational capabilities of passive sensors. This combination offers a high potential for profiling atmospheric parameters in an enlarged vertical range nearly independently on the atmospheric conditions. In this work, we describe two different integration approaches for the improvement of water vapour profiling during cloudy condition through the combination of Raman lidar and microwave profiler measurements. These approaches are based on the use of Kalman filtering and Tikhonov regularization methods for the solution of the radiative transfer equation in the microwave region. The accuracy of the retrieved water vapour profiles during cloudy conditions is improved by the use of the water vapour Raman lidar profiles, retrieved up to a maximum height level located around the cloud base region (depending on their optical thickness), as a constraint to the obtained solution set. The presented integration approaches allow us to provide physically consistent solution to the inverse problem in the microwave region retrieving water vapour vertical profiles also in presence of thick clouds. The integration of Raman lidar and microwave measurements also provides a continuous high-resolution estimation of the water vapour content in the full troposphere and, therefore, a useful tool for the evaluation of model capability to capture mean aspects of the water vapour field in nearly all weather conditions as well as for the identification of possible discrepancies between observations and models.

Aerosol Higroscopicity addresses a particular aspect of aerosol, namely, the extent to which they have an affinity for water vapor. The size increase of aerosol particles resulting from uptake of water vapor has important implications for the direct scattering of radiation and, under the right circumstances, to form cloud droplets. Ultimately this effect should have an important effect on the Earth's radiative budget and belongs to a category well known as aerosol indirect effect. For this purposed we have used a single-wavelength backscatter LIDAR (532 nm), combined with thermodynamics considerations, to derivate the hygroscopic growing factor of aerosols over Sao Paulo metropolitan region. To test this factor assessment we employed data obtained in a single day, namely on 11 September 2007, when a well characterized humidity intrusion is onset due the transport of water vapor by a sea-breeze phenomenon. For this data, we calculated the backscatter coefficient at 532 nm, and used this parameter to obtain the hygroscopic growing factor, assuming a well-mixed boundary layer where a cloud cap condition is present or a well defined and pronounced mixing layer boundary are present and other thermodynamic assumptions. These assumptions guarantee that any changes in the backscatter coefficient are mainly due to changes in relative humidity, rather than in aerosol size distribution. The results shown here should be regarded as a first step on an ongoing monitoring process of aerosol growth factor and will in the near future be merged with a Water Vapor Raman Lidar system in order to have a simultaneous water vapor mixing ratio profile together with the aerosol profile and it should be mainly used when clear, low-aerosol load conditions are available.

Measurements of low-altitude cloud and its interaction with aerosol are analyzed with a multiple-wavelength elastic- Raman scattering lidar. Using the numerical experiment approach, we first evaluate the retrieval accuracy of cloud extinction from the Raman-lidar algorithms, in particular at the cloud edges. For the low-level water-phase cloud, the simulation also shows the dramatic variation of lidar-ratio, color-ratio and extinction-ratio with the small droplets and their correlation. Then, the measurement examples by CCNY elastic-Raman lidar illustrate that the small droplets probably appear at the cloud edges, which might imply the new particle formation or the cloudaerosol interaction.

Agriculture, through wind erosion, tillage and harvest operations, burning, diesel-powered machinery and animal production operations, is a source of particulate matter emissions. Agricultural sources vary both temporally and spatially due to daily and seasonal activities and inhomogeneous area sources. Conventional point sampling methods originally designed for regional, well mixed aerosols are challenged by the disrupted wind flow and by the small mobile source of the emission encountered in this study. Atmospheric lidar (LIght Detection And Ranging) technology provides a means to derive quantitative information of particulate spatial and temporal distribution. In situ point measurements of particulate physical and chemical properties are used to characterize aerosol physical parameters and calibrate lidar data for unambiguous lidar data processing. Atmospheric profiling with scanning lidar allows estimation of temporal and 2D/3D spatial variations of mass concentration fields for different particulate fractions (PM1, PM_2.5, PM₁₀, and TSP) applicable for USEPA regulations. This study used this advanced measurement technology to map PM emissions at high spatial and temporal resolutions, allowing for accurate comparisons of the Conservation Management Practice (CMP) under test. The purpose of this field study was to determine whether and how much particulate emission differs from the conventional method of agricultural fall tillage and combined CMP operations.

Brazil has an important role in the biomass burning, with the detection of approximately 100,000 burning spots in a single year (2007). Most of these spots occur in the southern part of the Amazon basin during the dry season (from August to november) and these emissions reach the southeast of the country, a highly populated region and with serious urban air pollution problems. With the growing demand on biofuels, sugarcane is considerably expanding in the state of Sao Paulo, being a strong contributor to the bad air quality in this region. In the state of Sao Paulo, the main land use are pasture and sugarcane crop, that covers around 50% and 10% of the total area, respectively. Despite the aerosol from sugarcane burning having reduced atmospheric residence time, from a few days to some weeks, they might get together with those aerosol which spread over long distances (hundreds to thousands of kilometers). In the period of June through February 2010 a LIDAR observation campaign was carried in the state of Sao Paulo, Brazil, in order to observe and characterize optically the aerosols from two distinct sources, namely, sugar cane biomass burning and industrial emissions. For this purpose 2 LIDAR systems were available, one mobile and the other placed in a laboratory, both working in the visible (532 nm) and additionally the mobile system had a Raman channel available (607 nm). Also this campaign counted with a SODAR, a meteorological RADAR specially set up to detect aerosol "echoes" and gas-particle analyzers. To guarantee a good regional coverage 4 distinct sites were available to deploy the instruments, 2 in the near field of biomass burning activities (Rio Claro and Bauru), one for industrial emissions (Cubatao) and others from urban sources (Sao Paulo). The whole campaign provide the equivalent of 30 days of measurements which allowed us to get aerosol optical properties such as backscattering/extinction coefficients, scatter and LIDAR ratios, those were used to correlate with air quality and meteorological indicators and quantities. In this paper we should focus on the preliminary results of the Raman LIDAR system and its derived aerosol optical quantities.

EARLINET, the European Aerosol Research Lidar NETwork, established in 2000, is the first coordinated lidar network for tropospheric aerosol study on the continental scale. The network activity is based on scheduled measurements, a rigorous quality assurance program addressing both instruments and evaluation algorithms, and a standardised data exchange format. At present, the network includes 27 lidar stations distributed over Europe. EARLINET performed almost continuous measurements since 15 April 2010 in order to follow the evolution of the volcanic plume generated from the eruption of the Eyjafjallajökull volcano, providing the 4-dimensional distribution of the volcanic ash plume over Europe. During the 15-30 April period, volcanic particles were detected over Central Europe over a wide range of altitudes, from 10 km down to the local planetary boundary layer (PBL). Until 19 April, the volcanic plume transport toward South Europe was nearly completely blocked by the Alps. After 19 April volcanic particles were transported to the south and the southeast of Europe. Descending aerosol layers were typically observed all over Europe and intrusion of particles into the PBL was observed at almost each lidar site that was affected by the volcanic plume. A second event was observed over Portugal and Spain (6 May) and then over Italy on 9 May 2010. The volcanic plume was then observed again over Southern Germany on 11 May 2010.

Eyjafjallajökull volcano eruptions of ash plumes starting on April 2010 paralyzed completely air traffic in Europe for several days. During the crisis, Leosphere collected 24/7 real time measurements of the backscatter profiles, taken by ALS polarizations lidars spread from Denmark to South of France in order to provide quick looks of the sky at regular intervals for different met agencies and for the Volcanic Ash Advisory Centres (VAAC) coordinated by UK MetOffice. Moreover, Meteo France supported by other institutions such as CNRS (Centre National de la Recherche Scientifique), CEA (Commissariat à l'Energie Atomique), CNES (Centre National d'Études Spatiales) and Leosphere performed several test flights over France and North Atlantic with an airborne Lidar. These unique data allowed detection and identification of ash plume and provided a guidance regarding the decision-making chain. The ash mass concentration and its calculation were also discussed.

From 16-24 April 2010 multiwavelength EARLINET Raman lidar and AERONET Sun photometer measurements were performed at the Leibniz Institute for Tropospheric Research (IfT) in Leipzig (51.3° N, 12.5° E), Germany, to monitor the ash layers originating from the eruptions of the Eyjafjallajokull volcano in southern Iceland. We observed the first ash plumes on 16 April 2010. They showed strong depolarization which indicates non-spherical particles. Extinction coefficients were as high as 500 Mm^-1. We estimate ash mass concentrations of the order of 1000 μg/m³ in the main plume. For an aged ash plume on 19 April 2010 we observed much lower extinction coefficients of around 50 Mm^-1 which lead to estimated ash mass concentrations of the order of 100 μg/m³.

Measurements of the Eyjafjallajokull-plume were - from the beginning - continuously conducted at Munich, Germany, with two EARLINET Raman- and depolarization-lidars. By means of range corrected signals the temporal development of the ash-plume could be documented in real-time. The optical characterization includes the backscatter coefficient at three wavelengths (1064 nm, 532 nm, 355 nm), and the extinction coefficient and particle linear depolarization ratio at two (532 nm, 355 nm). The maximum extinction coefficient was as high as 0.75km^-1 and wavelength independent - a strong indication for large particles. The particle linear depolarization ratio was 0.35-0.37, indicating non-spherical particles. An inversion of the optical data considering the nonspherical shape of ash particles led to a maximum mass concentration in the order of 1.1 mg/m³ over Munich, however, relative uncertainties of more than 30% must be expected.

Located at a distance more than 3400Km from Iceland, where the eruption of Eyjafjallajökull volcano occurred, Romania was under the influence of volcanic ash transported by middle altitude air masses across Europe. Apart from two clear episodes on April 18 and April 21, 2010 the mix of volcanic ash with Saharan dust was detected by the multiwavelength Raman lidar in Bucharest. Optical properties of aerosol layers for these particular cases showed an increase of the linear particle depolarization, as well as a decrease of the Angstrom exponent, compared with the pure long-range transported volcanic ash. The case of May 5^th, 2010 is analyzed from lidar and ground-level data, accounting for layer dynamics, optical properties and chemical composition. Using high resolution lidar data we could make a clear distinction between ash and dust layers up to their mixing in the PBL. In order to account for similarities and differences, the same analysis was done for May 10^th and 11^th, when several distinct layers were depicted. The signature of ash (sulfate) was identified by Aerosol Mass Spectrometer at ground-level, on May 5^th and May 11^th.

The arrival of the volcanic ash plume of the Eyjafjallajökull eruption was observed over Greece almost one week after its major eruption (on April 14, 2010) with two multi-wavelength Raman lidar systems, members of the EARLINET network. Intensive lidar measurements were performed throughout the event over Thessaloniki and Athens to derive the optical properties of the ash aerosols in the troposphere. During April 21, 2010 two layers of volcanic ash were present over Thessaloniki, one around 2.5 and one around 5 km height after circulating over central Europe. The first layer was persistent but with variable thickness, while the thin layer observed at 5 km height disappeared after some hours. Later on and at higher altitudes thin layers of ash were observed between 5 and 8 km, directly associated with the volcanic eruption. The observed layer at around and 3 km was persistently observed till April 28. The volcanic ash was observed over Athens, after passing over Southern Italy, during April and May 2010, in two height regions: between 6-10 km height and between 4 km and the ground level. We found that this was directly linked to the maximum height of the emitted volcanic ash. The most intensive period for ash presence over Athens was between April 21 and 23. In most cases, ash layers were very well stratified in the form of filaments starting around 3-4 km down to 1.5 km height. Mixing of ash with locally produced aerosols was frequently observed during the measuring period resulting to enhanced PM₁₀ concentrations at ground level. Volcanic ash was also observed during May 10-11 and 17-19, 2010, after being transported over Spain and Northern Italy. Both over Athens and Thessaloniki Saharan dust particles were mixed with volcanic ones on certain days of May 2010, which resulted to more complicated structures of the aerosol layers observed over Greece.

During the eruption phase of the Icelandic volcano Eyjafjallajökull in April/May 2010 the University of Applied Sciences Duesseldorf has performed 14 measurement flights over north-western Germany in the time period of 23 April 2010 to 21 May 2010. Additionally 4 flights have been performed for visual observations, referencing and transfer. The measurement flights have been performed in situations, where the ash plume was present over north-western Germany as well as in situations, when there was no ash plume predicted. For the measurements a light aircraft (Flight Design CTSW Shortwing) was used, which was equipped with an optical particle counter (Grimm 1.107). Additionally the aircraft was equipped for one flight with an UV-DOAS system and a CO₂-measurement system. The optical particle counter allowed in-situ measurements of the particle distribution between 250 nm and 32 μm and of PM₁₀, PM_2.5 and PM₁. The ash plume appeared during the measurements as inhomogeneous in structure. Layers or multilayers of one hundred meters to a few hundred meters vertical depth of ash plume could be identified. Sub-plumes with a horizontal extension of several kilometres to several tenths of kilometres could be found. The layers of the ash plume could be found in altitudes between 2500m and 4500m. The measured concentrations have been compared with the concentration and extension of the ash plume predicted by the Volcanic Ash Advisory Centre (VAAC).

In this paper, a ground-based UV-polarization Lidar is used to characterize the optical properties of volcanic particles that originated from the Eyjafjöll volcano (63.63°N, 19.62°W, Iceland) and advected over Lyon (45.76°N, 4.83°E, France), a distance 2,600 kilometers away. The volcanic origin of the observed particles has been confirmed with 7-days air mass back-trajectories and FLEXPART dispersion model. The measured UV-particle backscattering coefficient is typically equal to 4 × 10^-6 m^-1.sr^-1. UV-depolarization ratios measurements have been performed in the troposphere of Lyon to measure the degree of volcanic particle non-sphericity. Experimental efforts have been done to determine the systematic errors contributing to the retrieved UV-particle depolarization ratio δ_p. The precision on retrieved δ_p-values is hence dominated by the uncertainty on the extinction to backscatter ratio S = 55 ± 10. It follows that the microphysical properties of the observed volcanic aerosols are quite difficult to retrieve from δ_p. However, a main volcanic layer of 2 kilometres width has been observed in the troposphere of Lyon, where measured UV δ_p-values reach up to (30 ± 10) %, showing that the observed highly dispersed and aged volcanic particles are irregular-shaped particles, even at more than 2,000 km from the Eyjafjöll volcano.

The Eyjafjallajökull volcano eruptions during mid April 2010 influenced European air traffic basically. This was mainly due to the low melting point of ejected material and the sharp-edged form of particles. As there is the necessity to understand the dispersion of such an ash cloud we assess the existing measurement networks and evaluate the existing numerical models (MCCM). We use data from ceilometers to detect the vertical distribution of the volcanic cloud. Ground-based in situ measurements of particle concentrations, sulphur dioxide and further parameters complete the data basis. The analysis concentrates on the spatial and temporal features of the event over Southern Germany. It is an initiative of a scientific cooperation on aerosols in the area of Augsburg (500 m altitude) - Munich (550 m) - Hohenpeißenberg (1000 m) - Zugspitze / Schneefernerhaus (2650 m). The period from the evening of April 15^th to the evening of April 20^th, 2010 is covered. Main emphasis is laid on shorter events: (1) the first 15 hours of April 17^th when the first cloud moved over Southern Germany, (2) the night from April 17^th to April 18^th when a second puff arrived over Southern Germany, and (3) the afternoon of April 19^th when another puff arrived over Southern Germany. Back trajectories are used to check the origin of the observed dust clouds. Results from the model simulations with MCCM for the whole period will be compared with the measurement results. We will draw conclusions about the predictability of such events, the abilities of numerical models, the possible relevance for near-surface air quality as well as the possible enhancements of existing observation networks and simulation systems.

The laser scanning system of a lidar usually needs a laser scanner with characteristics such as fast linear scanning, small size and small rotational inertia moment. Traditional laser scanners, such as galvanometer and rotating multi-faceted mirror, are difficult to achieve fast linear scanning with low moment of inertia. In order to solve these problems, a piezoelectric optical scanner based on novel piezoelectric actuator is designed in this paper. First of all, the scanner system components based on self-learning feed-forward controller is introduced. Furthermore, the principle and method of amending the scanner hysteresis loop are analyzed. Finally, one-dimensional linear scanning in a wide range of frequencies using the control platform with the core of digital signal processor TMS320F2812 is achieved. The experimental results show that the hysteresis characteristics have been restrained and scanning linear performance of the piezoelectric optical scanner has been remarkably improved in low frequencies. In high frequencies, the nonlinearity of triangle wave scanning is reduces by adding a notch filter circuit which restrained the structure resonance of the scanner. The piezoelectric optical scanner also has other advantages such as large optical scanning angle, high first step resonance frequency, small size and simple structure.

We report on the development of a scanning mobile Mie-fluorescence lidar for the detection and identification of biological and non-biological aerosols in the lower troposphere. Our lidar system has the capability to perform azimuth and elevation angle scans with an angular resolution of 0.1° in both day-time and night-time conditions. As the transmitter, we use a solid state Nd:YAG laser with simultaneous emission of 8 ns light pulses at 1064 nm and 266 nm with a maximum repetition rate of 10 Hz. Scattered light is collected by a Newtonian telescope with a diameter of 300 mm. The receiver consists of three channels for the detection of elastic scattering signals at 1064 nm and 266 nm as well as the fluorescence signal of the amino-acid tryptophan intrinsic to biological substances with a local peak at 295 nm. An important benchmark of the system are the aerosol loading measurements pending the eruption of the Icelandic Eyjafjallajokull volcano on 14 April 2010. Experiments on 20 April 2010 showed an elevated aerosol layer at an altitude of 2500 m a.s.l., which was confirmed as a layer of volcanic ash by other experiments. We also present first two-dimensional measurements of aerosol loading in urban areas, which can be of assistance in locating the aerosol sources, their dispersal trajectories, and simulation results for tryptophan fluorescence signal from biological aerosols.

Solar radiation reflected by the Earth's surface to satellite sensors is modified by its interaction with the atmosphere. The objective of atmospheric correction is to determine true surface reflectance values by removing atmospheric effects from satellite images. Atmospheric correction is arguably the most important part of the pre-processing of satellite remotely sensed data. The most important parameter in applying any atmospheric correction is the aerosol optical thickness which is also used for assessing air pollution. This paper explores how the AOT is extracted from atmospheric corrected satellite imagery acquired from Landsat ETM + and how then AOT values are used to assess air pollution. The atmospheric correction algorihm developed by Hadjimitsis and Clayton (2009) is applied to short wavelengths like Landsat TM band 1 and 2 (0.45-0.52μm, 0.52-0.60 μm). The results are also assessed using Lidar system and Cimel Sunphotometer located in the premises of the Cyprus University of Technology in Limassol. The authors run the atmospheric correction developed by Hadjimitsis and Clayton (2009) in MATLAB and sample AOT results for the Landsat ETM+ images acquired on the 15/01/2010, 20/4/2010, 09/06/2010 are shown. For the Landsat ETM+ image acquired on 20/4/2010, the AOT was found 1.4 after the application of the atmospheric correction. Such value complies with the AOT value measured by the Cimel Sun-photometer (AERONET) during the satellite overpass. An example of how Lidar is used to assess the existing atmospheric conditions which is useful for assessing air pollution is also presented.

The PBL is the lower layer of the atmosphere that is sensitive to the effect of the Earths surface, it controls the flow of heat and momentum between the surface and the free atmosphere, thus playing a key role in atmospheric circulation. At University of Rome "Tor Vergata", Quantum Electronic and Plasma Laboratories (EQP), two mobile Light Detection and Ranging (LIDAR) systems have been developed. With these systems the monitoring of the Planetary Boundary Layer (PBL) has been performed. The first mobile Lidar system is based on a pulsed Nd:YAG Q-Switched laser source operating at three wavelengths: 1064 nm, 532 nm and 355 nm. Acquiring the elastic backscattered signals, it has been possible to estimate the aerosolitic backscattering coefficient at the aim to reconstruct the vertical aerosol profiles. The second one is a Differential Absorption Lidar system (DIAL), composed by a CO2 laser, working in the window spectral range between 9 and 11μm. With this system it has been estimated the water vapour concentration in the PBL region using the two wavelengths 10R20 (10.591 μm) and 10R18 (10.571 μm), which represent, respectively, the absorbing wavelength and non-absorbing one of the water molecule. The comparison of the backscattered radiation at these wavelengths yields the trace gas number density as a function of distance along the field-of-view of the receiving telescope. Diurnal and nocturnal measurements have been performed simultaneity using the two Lidar/Dial systems. Vertical profiles of the aerosolitic backscattering coefficient and water vapour concentration profiles have been estimated. The results and their comparison will be present in this work.