This PDF file contains the front matter associated with SPIE Proceedings Volume 9246, including the Title Page, Copyright information, Table of Contents, Introduction (if any), and Conference Committee listing.

Double-pulse 2-micron lasers have been demonstrated with energy as high as 600 mJ and up to 10 Hz repetition rate. The two laser pulses are separated by 200 µs and can be tuned and locked separately. Applying double-pulse laser in DIAL system enhances the CO₂ measurement capability by increasing the overlap of the sampled volume between the on-line and off-line. To avoid detection complicity, integrated path differential absorption (IPDA) lidar provides higher signal-to-noise ratio measurement compared to conventional range-resolved DIAL. Rather than weak atmospheric scattering returns, IPDA rely on the much stronger hard target returns that is best suited for airborne platforms. In addition, the IPDA technique measures the total integrated column content from the instrument to the hard target but with weighting that can be tuned by the transmitter. Therefore, the transmitter could be tuned to weight the column measurement to the surface for optimum CO₂ interaction studies or up to the free troposphere for optimum transport studies. Currently, NASA LaRC is developing and integrating a double-Pulsed 2-µm direct detection IPDA lidar for CO₂ column measurement from an airborne platform. The presentation will describe the development of the 2-μm IPDA lidar system and present the airborne measurement of column CO₂ and will compare to in-situ measurement for various ground target of different reflectivity.

Currently one of the main challenges in CO₂ storage research is to grant the development, testing and validation of accurate and efficient Measuring, Monitoring and Verification (MMV) techniques to be deployed at the final storage site, targeting maximum storage efficiency at the minimal leakage risk levels. For such task a mimetic sequestration site has been deployed in Florianopolis, Brazil, in order to verify the performance of monitoring plataforms to detect and quantify leakages of ground injected CO₂, namely a Cavity Ring Down System (CRDS) - Los Gatos Research - an Eddy Covariance System (Campbell Scientific and Irgason) and meteorological tower for wind, humidity, precipitation and temperature monitoring onsite. The measurement strategy for detecting CO₂ leakages can be very challenging since environmental and phytogenic influence can be very severe and play a role on determining if the values measured are unambiguous or not. One external factor to be considered is the amount of incoming solar radiation which will be the driving force for the whole experimental setup and following this reasoning the amount of aerosols in the atmospheric column can be a determinant factor influencing the experimental results. Thus the investigation of measured fluxes CO₂ and its concentration with the aforementioned experimental instruments and their correlation with the aerosol data should be taken into account by means of satellite borne systems dedicated to measure aerosol vertical distribution and its optical properties, in this study we have selected CALIPSO and MODIS instrumentation to help on deriving the aerosol properties and CO2 measurements.

Integrated path differential absorption (IPDA) lidar is a remote sensing technique for monitoring different atmospheric species. The technique relies on wavelength differentiation between strong and weak absorbing features normalized to the transmitted energy. 2-μm double-pulsed IPDA lidar is best suited for atmospheric carbon dioxide measurements. In such case, the transmitter produces two successive laser pulses separated by short interval (200 μs), with low repetition rate (10Hz). Conventional laser energy monitors, based on thermal detectors, are suitable for low repetition rate single pulse lasers. Due to the short pulse interval in double-pulsed lasers, thermal energy monitors underestimate the total transmitted energy. This leads to measurement biases and errors in double-pulsed IPDA technique. The design and calibration of a 2-μm double-pulse laser energy monitor is presented. The design is based on a highspeed, extended range InGaAs pin quantum detectors suitable for separating the two pulse events. Pulse integration is applied for converting the detected pulse power into energy. Results are compared to a photo-electro-magnetic (PEM) detector for impulse response verification. Calibration included comparing the three detection technologies in singlepulsed mode, then comparing the pin and PEM detectors in double-pulsed mode. Energy monitor linearity will be addressed.

A compact mobile differential absorption lidar (DIAL) system has been developed at NASA Langley Research Center to provide ozone, aerosol and cloud atmospheric measurements in a mobile trailer for ground-based atmospheric ozone air quality campaigns. This lidar is integrated into the Tropospheric Ozone Lidar Network (TOLNet) currently made up of four other ozone lidars across the country. The lidar system consists of a UV and green laser transmitter, a telescope and an optical signal receiver with associated Licel photon counting and analog channels. The laser transmitter consists of a Q-switched Nd:YLF inter-cavity doubled laser pumping a Ce:LiCAF tunable UV laser with all the associated power and lidar control support units on a single system rack. The system has been configured to enable mobile operation from a trailer and was deployed to Denver, CO July 15-August 15, 2014 supporting the DISCOVER-AQ campaign. Ozone curtain plots and the resulting science are presented.

An airborne Doppler Wind Lidar has been used in several atmospheric boundary layer field experiments over the past decade. These experiments have taken place in California (Salinas Valley and the Monterey Peninsula), Arizona (Yuma Proving Grounds), and Utah (Dugway Proving Grounds). A primary objective of these field experiments was to compare model predicted winds in mountainous areas with wind observations obtained from the lidar measurements. To accomplish this, there is a basic challenge to determine when a comparison is valid in space and time. Here we have introduced the case for combining 12 pint step stare scans (conical) with near nadir stares to better represent the vertical air motions in complex terrain. We have also described a new scanning pattern that allows for LOS intersections for desired altitudes such as a ridge line or a valley floor.

Knowledge derived from global tropospheric wind measurement is an important constituent of our overall understanding of climate behavior [1]. Accurate weather prediction saves lives and protects properties from destructions. High-energy 2-micron laser is the transmitter of choice for coherent Doppler wind detection. In addition to the eye-safety, the wavelength of the transmitter suitably matches the aerosol size in the lower troposphere. Although the technology of the 2-micron laser has been maturing steadily, lidar derived wind data is still a void in the global weather database. In the last decade, researchers at NASA Langley Research Center (LaRC) have been engaged in this endeavor, contributing to the scientific database of 2-micron lidar transmitters. As part of this effort, an in depth analysis of the physics involved in the workings of the Ho: Tm laser systems have been published. In the last few years, we have demonstrated lidar transmitter with over1Joule output energy. In addition, a large body of work has been done in characterizing new laser materials and unique crystal configurations to enhance the efficiency and output energy of the 2-micron laser systems. At present 2-micron lidar systems are measuring wind from both ground and airborne platforms. This paper will provide an overview of the advancements made in recent years and the technology maturity levels attained.

Polar stratospheric clouds (PSCs) are known to play key roles in the springtime chemical depletion of ozone at high latitudes. PSC particles provide sites for heterogeneous chemical reactions that transform stable chlorine and bromine reservoir species into highly reactive ozone-destructive forms. Furthermore, large nitric acid trihydrate (NAT) PSC particles can irreversibly redistribute odd nitrogen through gravitational sedimentation, which prolongs the ozone depletion process by slowing the reformation of the stable chlorine reservoirs. Spaceborne observations from the CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) lidar on the CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) satellite are providing a rich new dataset for studying PSCs. CALIOP began data collection in mid-June 2006 and has since acquired, on average, over 300,000 backscatter profiles daily at latitudes between 55° and 82° in both hemispheres. PSCs are detected in the CALIOP backscatter profiles as enhancements above the background aerosol in either 532-nm scattering ratio (the ratio of total-to-molecular backscatter) or 532-nm perpendicular-polarized backscatter. CALIOP PSCs are separated into composition classes based on the ensemble 532- nm scattering ratio and 532-nm particulate depolarization ratio (which is sensitive to the presence of non-spherical, i.e. NAT and ice particles). In this paper, we provide an overview of the CALIOP PSC measurements and then examine the vertical and spatial distribution of PSCs in the Arctic and Antarctic on vortex-wide scales for entire PSC seasons over the more than eight-year data record.

From August 2012 to February 2013 a High Resolution Spectral Lidar (HSRL; 532 nm) was deployed at that National University of Singapore near a NASA Micro Pulse Lidar NETwork (MPLNET; 527 nm) site. A primary objective of the MPLNET lidar project is the production and dissemination of reliable Level 1 measurements and Level 2 retrieval products. This paper characterizes and quantifies error in Level 2 aerosol optical property retrievals conducted through inversion techniques that derive backscattering and extinction coefficients from MPLNET elastic single-wavelength datasets. MPLNET Level 2 retrievals for aerosol optical depth and extinction/backscatter coefficient profiles are compared with corresponding HSRL datasets, for which the instrument collects direct measurements of each using a unique optical configuration that segregates aerosol and cloud backscattered signal from molecular signal. The intercomparison is performed, and error matrices reported, for lower (0-5km) and the upper (>5km) troposphere, respectively, to distinguish uncertainties observed within and above the MPLNET instrument optical overlap regime.

Comprehension about the behavior of the Planet Boundary Layer (PBL) is an important factor in several fields, from analysis about air quality until modeling. However, monitoring the PBL evolution is a complex problem, because few instruments can provide continuous atmospheric measurements with enough spatial and temporal resolution. Inside this scenario lidar systems appear as an important tool, because it complies with all these capabilities- However, PBL observations are not a direct measure, being necessary to use complex mathematic algorithms. Recently, wavelet covariance transforms have been applied in this field. The objective of this work is to compare the performing of distinct types of algorithms: a structured on Haar wavelet and other based on first derivative of Gaussian and Mexican Hat wavelets, and the results were compared with two Hysplit modelling. For this aim, two campaigns were carried out. From the results were possible to infer that both algorithms provide coherent results as the expected, but the Haar algorithm separates the sub-layers more efficiently, so it is the most appropriate to complex situations.

Since 2005, the high-performance multiparameter Raman lidar RAMSES (Raman lidar for atmospheric moisture sensing) for water vapor, temperature, cloud and aerosol measurements is part of the broad suite of active and passive remote-sensing instruments monitoring the atmosphere at the German Meteorological Services observatory in Lindenberg. Initially housed in a 20-foot container, continued expansion of RAMSES made accommodation of the instrument increasingly difficult, and caused problems in air-conditioning. For these reasons, a new lidar facility was built on site in 2013. It is now home to RAMSES, and it also provides extra laboratory space for (lidar) experiments. The Lindenberg lidar facility is described in detail. One of its features is the precision air-conditioning system which is designed to keep the temperature field of the RAMSES room stable within 1 K at all times. Migration from the container to the new building offered an opportunity to make changes to the RAMSES instrument itself. For instance, stray light suppression was further improved, selection of photomultiplier tubes was optimized, and the near-range receiver was redesigned to enhance its daytime capabilities. Further, in addition to the water spectrometer for calibrated measurements of cloud Raman backscatter-coefficient spectra, a second spectrometer was implemented for studies of the fluorescence spectra of atmospheric aerosols. At the conference, these technical modifications are discussed, and first measurement examples with the improved lidar are presented.

The LED mini-lidar has been designed and demonstrated as the near range atmosphere monitoring, dust and gas detections. The LED lamp is used as a lidar light source. It is not a special one, and just used as a small status indicator or a spot luminaire. For the atmospheric monitoring in the near range of a few hundreds meters, the energy of 1nJ (=100mW/10ns) is enough for lidar observation in the nighttime. The LED lamp is excited at the high repetition frequency of < 1MHz. The signal-to-noise ratio can be increased by this high frequency even if the receiving photons are a little at each pulse. It is adequate because the spatiotemporal scale of the low-altitude atmosphere is small of a ten seconds and a few tens meters. To pursue such quick motion of the atmosphere and dust, the high-speed photon counter has been developed. It can act with BIN width of 4ns (Spatial resolution 0.6m) at the repetition frequency of <500kHz. The LED mini-lidar has been demonstrated to monitor the actual atmosphere of the observation range of <500m in the nighttime and <100m in the daytime with the receiving lens of 200mmφ. The interest approach is tired to distinguish the dust characteristics by using the counting rate of dust echoes. It is effective in the case that the dust material is given. And for trial, the LED mini-Raman-lidar is developed to monitor certain gas detection in near distance, too.

Aerosol hygroscopicity is a property that reveals the ability of an aerosol particle to grow under increasing values of relative humidity. The hygroscopic behavior has a significant effect on radiative properties of aerosols, and therefore on cloud formation, aerosol-cloud interaction and, consequently, on the Earth’s climate. In this work, a Raman LIDAR is used to determine the hygroscopic growth factor f_β (RH) under unperturbed, ambient atmospheric conditions in a well-mixed boundary layer in São Paulo metropolitan city. To this aim, the water vapor mixing ratio (required to derive the hygroscopic growth factor) was independently obtained by radiosoundings and Raman LIDAR (after the corresponding calibration using radiosoundings), and the hygroscopic growth factor was determined using both instruments. There is a good agreement between the values obtained by the LIDAR and by the radiosoundings, although many uncertainties still remain in the hygroscopic growth factor determination. It suggests that the Raman LIDAR method can provide useful measurements of the dependence of aerosol optical properties on relative humidity and under conditions closer to saturation.

The so-called Metropolitan Area of São Paulo, one of the largest megacities in the world, faces several problems related to the air quality due the high concentrations of aerosols produced either by local sources or by long-range transporting. Concerned with the elevated concentrations of aerosol and their impact in the air quality and the climate changes inside MASP, a measurement campaign were conducted during the South hemisphere winter of 2012, when the low temperatures and the low level of precipitation contribute to the poor dispersion of aerosols. A Raman Lidar system and air quality monitoring stations from University of São Paulo and Environment Agency of São Paulo State (CETESB) were employed in order to monitor the increasing of aerosol load in the atmosphere. Satellite data, in synergy with HYSPLIT air masses backward trajectories, were applied to track the aerosol from the long-range distanced regions to Metropolitan Area of São Paulo. In the beginning of September 2012, MASP experienced episodes of high air pollution concentration, reaching Aerosol Optical Depth (AOD) values up to 0.89 at 550 nm and particulate matter concentration up to 293 µ g/cm³ . Particle lidar ratio values of 60 to 70 sr retrieved by a Raman Lidar system at 532 nm provided information of the aerosol type, helping to determine the influence of biomass burning advected from large range distance to megacities such as São Paulo

Atmospheric profiles of the optical aerosol properties through the retrieved backscattering or extinction coefficients by lidar measurements can improve drastically the MACC-II aerosol model performances on vertical dimension. Currently the MODIS Aerosol Optical Depth data (both from Terra and Aqua) are assimilated into the model. Being a columnintegrated quantity, these data do not modify the model aerosol vertical profile, especially if the aerosols are not interactive with the meteorology. Since 1999, the MPLNET lidar network provides continuously lidar data measurements from worldwide permanent stations (currently 21), deployed from the Arctic to the Antarctic regions and in tropical and equatorial zones. The purpose of this study is to show the first preliminary results of the intercomparison of MPLNET lidar data against the ECWMF MACC-II aerosol model, for a selected MPLNET permanent observational site at National Central University of Taiwan. Assessing the model performances it is the first step for future near-real time lidar data assimilation into MACC-II aerosol model forecast.

As a way of acquiring elevation with high accuracy, space-borne laser altimeter improves the capability of 3-dimensional cartography of satellite optical remote sensing imagery. However, the plane accuracy of space-borne laser altimeter is not so high as its elevation accuracy. Accordingly, the error souses and their influences on space-borne laser altimeter ground positioning are studied in this paper. The space-borne laser altimeter is very different from classical photogrammetry, the elevation information is obtained by measuring the time between sending and receiving the laser. As space-borne laser altimeter supplies laser echo signal other than image, the positioning accuracy is more important as well as the exterior orientation elements. The ground positioning of space-borne laser altimeter is first modeled, then error propagation of the model is studied, and the main error souses of space-borne laser altimeter ground positioning are obtained. At last the influences of each error souse on space-borne laser altimeter ground positioning are analysed as the references for space-borne laser altimeter designing and application.

A broad suite of ground-based remote sensing instruments of the Meteorological Observatory Lindenberg, Germany, is combined for the first time to synergistically analyze cirrus cloud microphysics, including a Raman lidar, a Ka band cloud radar and a 5ff tilted ceilometer. 84 days of cirrus cloud measurements have been selected to study the correlation between, and the dependences of, the different measured variables. The presented study investigates the effect of the spatial orientation and the shape of solid cloud particles on particle optical properties and their relation to wind and turbulence parameters. A sensitive indicator of particle spatial orientation is the particle depolarization ratio (PDR). When ice crystals are horizontally aligned, mirror reflections can occur, which is evidenced by low PDR if observed with a vertically pointing Raman lidar. Observations are grouped according to the prevailing weather condition. It is found that on some days PDR is constant for long time periods. Interestingly, during warm fronts the PDR is generally small (<0.2), while during cold fronts it is high (> 0.4). Moreover, the mean lidar ratio of cirrus with high PDR is about 20 sr, two times larger than of cirrus with low PDR. Similar dependences on PDR have been found for the particle extinction coefficient, and for the backscatter coefficient from the tilted ceilometer, but for the Raman lidar backscatter coefficient in perpendicular polarization the opposite behavior is observed.

The water vapor profile derived from Raman lidar measurements is obtained by taking the ratio of water vapor and nitrogen Raman-shifted signals. The proportionality factor that converts the signal ratio to water vapor/air mixing ratio is referred to as lidar calibration constant. The calibration constant depends on the water vapor and nitrogen Raman cross sections and on the efficiencies of the respective Raman channels including the photomultiplier tube (PMT) efficiency. Unequal, gradual changes in the PMTs efficiencies due to fatigue effects may lead to gradual alteration of the calibration constant. Such an effect has been observed during the seven- year continuous operation of the RAman Lidar for Moisture Observations (RALMO)¹ . A more detailed research² , has shown that the calibration constant change is more pronounced during summer time probably due to the higher light exposure. Periodical recalibration of the lidar with radiosonde measurements is used to correct the calibration constant. This approach, however, induces additional systematic errors due to the nature of the calibration procedure and the dispersion of the radiosonde parameters. We present a new, instrumental method for automated correction of the calibration constant. By this method, a correction factor is deduced from the ratio of the signals of the two photomultipliers which are illuminated simultaneously by a single, stabilized UV-LED light source. The LED light is delivered to the photomultipliers by a set of additional mirrors and a beam splitter installed inside the grating polychromator used to separate the Raman signals. The correction measurements are taken before midnight. To minimize the data loss, the lidar’s laser is operated during the measurements and a shatter at the polychromator entrance is used to block any atmospheric signals. The use of stabilized light source also allows evaluating the individual photomultipliers aging rates, essential for the instrument maintenance.

The Latin American Lidar Network (LALINET) is the aerosol lidar network operating over South America. LALINET is now an operative network performing a schedule of routine measurements and, currently, is composed by 9 stations distributed over South America. The main objective of LALINET is to generate a consistent and statistically relevant database to enhance the understanding of the particle distribution over the continent and its direct and indirect influence on climate. The creation of an un-biased spatiotemporal database requires a throughout review of the network on two pillars: instrumentation and data processing. Because most of the LALINET systems are not series-produced instruments and, therefore, present large differences in configuration and capabilities, attempts for network harmonization and, consequently, optimization are mandatory. In this study a review of the current instrumental status of all LALINET systems is done and analyzed in detail in order to assess the potential performance of the network and to detect networking weaknesses.

An adaptive segmentation smoothing method (ASSM) is introduced in the paper to smooth the signal and suppress the noise. In the ASSM, the noise is defined as the 3σ of the background signal. An integer number N is defined for finding the changing positions in the signal curve. If the difference of adjacent two points is greater than 3Nσ, the position is recorded as an end point of the smoothing segment. All the end points detected as above are recorded and the curves between them will be smoothed separately. In the traditional method, the end points of the smoothing windows in the signals are fixed. The ASSM creates changing end points in different signals and the smoothing windows could be set adaptively. The windows are always set as the half of the segmentations and then the average smoothing method will be applied in the segmentations. The Iterative process is required for reducing the end-point aberration effect in the average smoothing method and two or three times are enough. In ASSM, the signals are smoothed in the spacial area nor frequent area, that means the frequent disturbance will be avoided. A lidar echo was simulated in the experimental work. The echo was supposed to be created by a space-born lidar (e.g. CALIOP). And white Gaussian noise was added to the echo to act as the random noise resulted from environment and the detector. The novel method, ASSM, was applied to the noisy echo to filter the noise. In the test, N was set to 3 and the Iteration time is two. The results show that, the signal could be smoothed adaptively by the ASSM, but the N and the Iteration time might be optimized when the ASSM is applied in a different lidar.

This paper has been withdrawn by the publisher because it was not presented at the conference.

A multi-wavelength fiber based MOPA-system is proposed to increase performance of coherent Doppler lidar systems. The setup of the four-wavelength lidar system is described and characterized. We show that the speckle patterns of each wavelength are uncorrelated. The measured Goodman’s M-parameter is 3.8 for four wavelengths, using hard target reflections. Atmospheric measurements show uncorrelated speckle patterns as well. Consequently, the precision of the measured wind velocity can be improved by a factor of two.

In the quest for a better understanding of climate change, greater importance is attached to monitoring the levels of atmospheric carbon dioxide to gain an improved knowledge of sources and sinks. Remote sensing is a critical tool in this research area and differential absorption lidar (DIAL) is one important technique. The laser is the critical component of a DIAL instrument. This paper describes the development of a laser source for the detection and measurement of carbon dioxide.

Atmospheric particulate matters (PM) are tiny pieces of solid or liquid matter associated with the Earth’s atmosphere. They are suspended in the atmosphere as atmospheric aerosol. Recently, density of fine particles PM2.5, diameter of 2.5 micrometers or less, from China is serious environmental issue in East part of Asia. In this study, the authors have developed a PM2.5 density distribution visualization system using ground-level sensor network dataset and Mie lidar dataset. The former dataset is used for visualization of horizontal PM2.5 density distribution and movement analysis, the latter dataset is used for visualization of vertical PM2.5 density distribution and movement analysis.

The determination of the amount of water vapor in the atmosphere using lidar is a calibration dependent technique. Different collocated instruments are used for this purpose, like radiossoundings and microwave radiometers. When there are no collocated instruments available, an independente lamp mapping calibration technique can be used. Aiming to stabilish an independ technique for the calibration of the six channels Nd-YAG Raman lidar system located at the Center for Lasers and Applications (CLA), S˜ao Paulo, Brazil, an optical characterization of the system was first performed using a reference tungsten lamp. This characterization is useful to identify any possible distortions in the interference filters, telescope mirror and stray light contamination. In this paper we show three lamp mapping caracterizations (01/16/2014, 01/22/2014, 04/09/2014). The first day is used to demostrate how the tecnique is useful to detect stray light, the second one how it is sensible to the position of the filters and the third one demostrates a well optimized optical system.