These are representative sample records from Science.gov related to your search topic.
For comprehensive and current results, perform a real-time search at Science.gov.
1

LOSA-M2 aerosol Raman lidar  

SciTech Connect

The scanning LOSA-M2 aerosol Raman lidar, which is aimed at probing atmosphere at wavelengths of 532 and 1064 nm, is described. The backscattered light is received simultaneously in two regimes: analogue and photon-counting. Along with the signals of elastic light scattering at the initial wavelengths, a 607-nm Raman signal from molecular nitrogen is also recorded. It is shown that the height range of atmosphere probing can be expanded from the near-Earth layer to stratosphere using two (near- and far-field) receiving telescopes, and analogue and photon-counting lidar signals can be combined into one signal. Examples of natural measurements of aerosol stratification in atmosphere along vertical and horizontal paths during the expeditions to the Gobi Desert (Mongolia) and Lake Baikal areas are presented.

Balin, Yu S; Bairashin, G S; Kokhanenko, G P; Penner, I E; Samoilova, S V [V.E. Zuev Institute of Atmospheric Optics, Siberian Branch, Russian Academy of Sciences, Tomsk (Russian Federation)

2011-10-31

2

Measurement of atmospheric aerosol extinction profiles with a Raman lidar  

Microsoft Academic Search

A method is presented that permits the determination of atmospheric aerosol extinction profiles from measured Raman lidar signals. No critical input parameters are needed, which could cause large uncertainties of the solution, as is the case in the Klett method for the inversion of elastic lidar returns.

Albert Ansmann; Maren Riebesell; Claus Weitkamp

1990-01-01

3

Improvement of Raman lidar algorithm for quantifying aerosol extinction  

NASA Technical Reports Server (NTRS)

Aerosols are particles of different composition and origin and influence the formation of clouds which are important in atmospheric radiative balance. At the present there is high uncertainty on the effect of aerosols on climate and this is mainly due to the fact that aerosol presence in the atmosphere can be highly variable in space and time. Monitoring of the aerosols in the atmosphere is necessary to better understanding many of these uncertainties. A lidar (an instrument that uses light to detect the extent of atmospheric aerosol loading) can be particularly useful to monitor aerosols in the atmosphere since it is capable to record the scattered intensity as a function of altitude from molecules and aerosols. One lidar method (the Raman lidar) makes use of the different wavelength changes that occur when light interacts with the varying chemistry and structure of atmospheric aerosols. One quantity that is indicative of aerosol presence is the aerosol extinction which quantifies the amount of attenuation (removal of photons), due to scattering, that light undergoes when propagating in the atmosphere. It can be directly measured with a Raman lidar using the wavelength dependence of the received signal. In order to calculate aerosol extinction from Raman scattering data it is necessary to evaluate the rate of change (derivative) of a Raman signal with respect to altitude. Since derivatives are defined for continuous functions, they cannot be performed directly on the experimental data which are not continuous. The most popular technique to find the functional behavior of experimental data is the least-square fit. This procedure allows finding a polynomial function which better approximate the experimental data. The typical approach in the lidar community is to make an a priori assumption about the functional behavior of the data in order to calculate the derivative. It has been shown in previous work that the use of the chi-square technique to determine the most likely functional behavior of the data prior to actually calculating the derivative eliminates the need for making a priori assumptions. We note that the a priori choice of a model itself can lead to larger uncertainties as compared to the method that is validated here. In this manuscript, the chi-square technique that determines the most likely functional behavior is validated through numerical simulation and by application to a large body of Raman lidar measurements. In general, we show that the chi-square approach to evaluate aerosol extinction yields lower extinction uncertainty than the traditional technique. We also use the technique to study the feasibility of developing a general characterization of the extinction uncertainty that could permit the uncertainty in Raman lidar aerosol extinction measurements to be estimated accurately without the use of the chi-square technique.

Russo, Felicita; Whiteman, David; Demoz, Belay; Hoff, Raymond

2005-01-01

4

2.1 RAMAN LIDAR PROFILING OF WATER VAPOR AND AEROSOLS OVER THE ARM SGP SITE  

E-print Network

2.1 RAMAN LIDAR PROFILING OF WATER VAPOR AND AEROSOLS OVER THE ARM SGP SITE Richard A. Ferrare *1 and Radiation Testbed (CART) Raman Lidar data acquired during both daytime and nighttime operations. This Raman lidar system is unique in that it is turnkey, automated system designed for unattended, around

5

Compact airborne Raman lidar for profiling aerosol, water vapor and clouds.  

PubMed

A compact airborne Raman lidar system, which can perform water vapor and aerosol measurements both during nighttime and daytime is described. The system design, setup and the data processing methods are described in the paper. The Raman lidar was tested on University of Wyoming King Air research aircraft (UWKA) during the Wyoming King Air PBL Exploratory Experiment (KAPEE) in 2010. An observation showing clouds, aerosols and a dry line is presented to illustrate the lidar detection capabilities. Comparisons of the water vapor and aerosol measurements using the Raman lidar and other in situ airborne instruments show good agreement. PMID:25321266

Liu, Bo; Wang, Zhien; Cai, Yong; Wechsler, Perry; Kuestner, William; Burkhart, Matthew; Welch, Wayne

2014-08-25

6

Is fluorescence of biogenic aerosols an issue for Raman lidar measurements?  

NASA Astrophysics Data System (ADS)

During a measuring campaign in Lindenberg/Germany (14.5°E, 52.5°N) in August 2003, we observed an extended aerosol layer in the upper troposphere with our mobile Aerosol Raman Lidar (MARL). Backward trajectories indicated that this was a plume originating from forest fires. Water vapor Raman measurements performed with the same lidar showed a large discrepancy with co-located radiosonde measurements, which were not observed in undisturbed conditions. We interpret the unexpected properties of these aerosols as fluorescence induced by the laser beam at organic components of the aerosol particles. The detection of fluorescence from ambient aerosol with lidar systems has not yet been reported before. However, organic compounds such as polycyclic aromatic hydrocarbons sticking to the aerosol particles, or bioaerosol such as bacteria, spores or pollen fluoresce when excited with UV-radiation in a way that is detectable by our lidar system. Therefore, we conclude that fluorescence from organic material released by biomass burning induces inelastic backscatter signals which could be observed with the lidar. It provides for a new method to characterize atmospheric aerosols and should be taken into account when performing water vapor measurements with a Raman lidar.

Immler, Franz; Schrems, Otto

2005-10-01

7

New Examination of the Raman Lidar Technique for Water Vapor and Aerosols. Paper 1; Evaluating the Temperature Dependent Lidar Equations  

NASA Technical Reports Server (NTRS)

The intent of this paper and its companion is to compile together the essential information required for the analysis of Raman lidar water vapor and aerosol data acquired using a single laser wavelength. In this first paper several details concerning the evaluation of the lidar equation when measuring Raman scattering are considered. These details include the influence of the temperature dependence of both pure rotational and vibrational-rotational Raman scattering on the lidar profile. These are evaluated for the first time using a new form of the lidar equation. The results indicate that, for the range of temperatures encountered in the troposphere, the magnitude of the temperature dependent effect can reach 10% or more for narrowband Raman water vapor measurements. Also the calculation of atmospheric transmission is examined carefully including the effects of depolarization. Different formulations of Rayleigh cross section determination commonly used in the lidar field are compared revealing differences up to 5% among the formulations. The influence of multiple scattering on the measurement of aerosol extinction using the Raman lidar technique is considered as are several photon pulse-pileup correction techniques.

Whiteman, David N.

2003-01-01

8

Aerosol characterization with lidar methods  

NASA Astrophysics Data System (ADS)

Aerosol component analysis methods for characterizing aerosols were developed for various types of lidars including polarization-sensitive Mie scattering lidars, multi-wavelength Raman scattering lidars, and multi-wavelength highspectral- resolution lidars. From the multi-parameter lidar data, the extinction coefficients for four aerosol components can be derived. The microphysical parameters such as single scattering albedo and effective radius can be also estimated from the derived aerosol component distributions.

Sugimoto, Nobuo; Nishizawa, Tomoaki; Shimizu, Atsushi; Matsui, Ichiro

2014-08-01

9

New Examination of the Traditional Raman Lidar Technique II: Temperature Dependence Aerosol Scattering Ratio and Water Vapor Mixing Ratio Equations  

NASA Technical Reports Server (NTRS)

In a companion paper, the temperature dependence of Raman scattering and its influence on the Raman water vapor signal and the lidar equations was examined. New forms of the lidar equation were developed to account for this temperature sensitivity. Here we use those results to derive the temperature dependent forms of the equations for the aerosol scattering ratio, aerosol backscatter coefficient, extinction to backscatter ratio and water vapor mixing ratio. Pertinent analysis examples are presented to illustrate each calculation.

Whiteman, David N.; Abshire, James B. (Technical Monitor)

2002-01-01

10

Turnkey Raman lidar for profiling atmospheric water vapor, clouds, and aerosols  

Microsoft Academic Search

We describe an operational, self-contained, fully autonomous Raman lidar system that has been developed for unattended, around-the-clock atmospheric profiling of water vapor, aerosols, and clouds. During a 1996 three-week intensive observational period, the system operated during all periods of good weather (339 out of 504 h), including one continuous five-day period. The system is based on a dual-field-of-view design that

J. E. M. Goldsmith; Forest H. Blair; Scott E. Bisson; David D. Turner

1998-01-01

11

Vertical Profiling of Atmospheric Backscatter with a Raman-Aerosol Lidar  

NASA Astrophysics Data System (ADS)

Aerosols have a strong impact on the planet's thermal balance, air quality, and a variety of atmospheric processes and phenomena. In this work we present some results from a long term lidar observation of tropospheric aerosols over the city of Sofia, Bulgaria, within the framework of the European project ``EARLINET-ASSOS.'' Vertical profiles of the aerosol backscattering coefficient and range corrected lidar signals are processed and analyzed. The temporal evolution and the spatial distribution of atmospheric aerosol fields are illustrated by 2D-colormaps in height-time coordinates. We present here several cases of aerosol loading: transport of Saharan dust (at altitudes from 3 km to 5 km), highly situated layers (from 9 km to 15 km), and anthropogenic smog (up to 2 km). All measurements were performed by using the two aerosol spectral channels of a combined Raman-aerosol lidar developed in the Laser Radar Lab, Institute of Electronics, Bulgarian Academy of Sciences. It is based on a Q-switched powerful frequency-doubled Nd:YAG laser (output pulse power: up to 1 J at 1064 nm; up to 100 mJ at 532 nm; pulse duration 15 ns FWHM; repetition rate 2 Hz). A Cassegrain telescope (35 cm diameter, 200 cm focal length) collects the backscattered radiation. The lidar receiving system is based on novel smart high sensitive photo-receiving modules. The acquisition system provides signal registration with spatial resolution of 15 m (100 MHz 14-bit ADC). It allows for detection, storage, and processing of large volume lidar data. Our observations are in good agreement with the forecasts of Barcelona Supercomputing Center, concerning Saharan dust transport.

Deleva, Atanaska D.; Peshev, Zahary Y.; Slesar, Alexander S.; Denisov, Sergey; Avramov, Lachezar A.; Stoyanov, Dimitar V.

2010-01-01

12

CART Raman Lidar Aerosol and Water Vapor Measurements in the Vicinity of Clouds  

NASA Technical Reports Server (NTRS)

Aerosol and water vapor profiles acquired by the Raman lidar instrument located at the Climate Research Facility (CRF) at Southern Great Plains (SGP) provide data necessary to investigate the atmospheric variability in the vicinity of clouds near the top of the planetary boundary layer (PBL). Recent CARL upgrades and modifications to the routine processing algorithms afforded the necessarily high temporal and vertical data resolutions for these investigations. CARL measurements are used to investigate the behavior of aerosol backscattering and extinction and their correlation with water vapor and relative humidity.

Clayton, Marian B.; Ferrare, Richard A.; Turner, David; Newsom, Rob; Sivaraman, Chitra

2008-01-01

13

Monitoring and characterization of atmospheric aerosols with Raman and dual-polarization lidars  

NASA Astrophysics Data System (ADS)

Atmospheric aerosols play a key role on climate balance (direct, semi-direct and indirect effects), on human health (increase of breathing problems and lung cancer for pollution aerosols) and human activities (damage to aircraft engines by volcanic ashes, reduction of visibility by dust or pollution aerosols). In order to monitor and characterize this threat it is necessary to localize, characterize and possibly quantify the presence of aerosols in the atmosphere from the lowest layers (~100 m) up to the tropopause (18 km). We use here an approach based on measurements of the new Raman and dual-polarization LiDAR R-Man510. We present in this paper how it is possible to detect atmospheric layers, to retrieve their optical properties and to classify these layers with this sensor.

Royer, P.; Sauvage, L.; Bizard, A.; Thobois, L.

2013-10-01

14

Intercomparison of aerosol optical parameters from WALI and R-MAN510 aerosol Raman lidars in the framework of HyMeX campaign  

NASA Astrophysics Data System (ADS)

The HyMeX program (Hydrological cycle in Mediterranean eXperiment) aims at improving our understanding of hydrological cycle in the Mediterranen and at a better quantification and forecast of high-impact weather events in numerical weather prediction models. The first Special Observation Period (SOP1) took place in September/October 2012. During this period two aerosol Raman lidars have been deployed at Menorca Island (Spain) : one Water-vapor and Aerosol Raman LIdar (WALI) operated by LSCE/CEA (Laboratoire des Sciences du Climat et de l'Environnement/Commissariat à l'Energie Atomique) and one aerosol Raman and dual-polarization lidar (R-Man510) developed and commercialized by LEOSPHERE company. Both lidars have been continuously running during the campaign and have provided information on aerosol and cloud optical properties under various atmospheric conditions (maritime background aerosols, dust events, cirrus clouds...). We will present here the results of intercomparisons between R-Man510, and WALI aerosol lidar systems and collocated sunphotometer measurements. Limitations and uncertainties on the retrieval of extinction coefficients, depolarization ratio, aerosol optical depths and detection of atmospheric structures (planetary boundary layer height, aerosol/cloud layers) will be discussed according atmospheric conditions. The results will also be compared with theoretical uncertainty assessed with direct/inverse model of lidar profiles.

Boytard, Mai-Lan; Royer, Philippe; Chazette, Patrick; Shang, Xiaoxia; Marnas, Fabien; Totems, Julien; Bizard, Anthony; Bennai, Baya; Sauvage, Laurent

2013-04-01

15

Dual-FOV Raman and Doppler lidar studies of aerosol-cloud interactions: Simultaneous profiling of aerosols, warm-cloud properties, and vertical wind  

NASA Astrophysics Data System (ADS)

For the first time, colocated dual-field of view (dual-FOV) Raman lidar and Doppler lidar observations (case studies) of aerosol and cloud optical and microphysical properties below and within thin layered liquid water clouds are presented together with an updraft and downdraft characterization at cloud base. The goal of this work is to investigate the relationship between aerosol load close to cloud base and cloud characteristics of warm (purely liquid) clouds and the study of the influence of vertical motions and turbulent mixing on this relationship. We further use this opportunity to illustrate the applicability of the novel dual-FOV Raman lidar in this field of research. The dual-FOV lidar combines the well-established multiwavelength Raman lidar technique for aerosol retrievals and the multiple-scattering Raman lidar technique for profiling of the single-scattering extinction coefficient, effective radius, number concentration of the cloud droplets, and liquid water content. Key findings of our 3 year observations are presented in several case studies of optically thin altocumulus layers occurring in the lower free troposphere between 2.5 and 4 km height over Leipzig, Germany, during clean and polluted situations. For the clouds that we observed, the most direct link between aerosol proxy (particle extinction coefficient) and cloud proxy (cloud droplet number concentration) was found at cloud base during updraft periods. Above cloud base, additional processes resulting from turbulent mixing and entrainment of dry air make it difficult to determine the direct impact of aerosols on cloud processes.

Schmidt, Jörg; Ansmann, Albert; Bühl, Johannes; Baars, Holger; Wandinger, Ulla; Müller, Detlef; Malinka, Aleksey V.

2014-05-01

16

New Examination of the Traditional Raman Lidar Technique II: Evaluating the Ratios for Water Vapor and Aerosols  

NASA Technical Reports Server (NTRS)

In a companion paper, the temperature dependence of Raman scattering and its influence on the Raman and Rayleigh-Mie lidar equations was examined. New forms of the lidar equation were developed to account for this temperature sensitivity. Here those results are used to derive the temperature dependent forms of the equations for the water vapor mixing ratio, aerosol scattering ratio, aerosol backscatter coefficient, and extinction to backscatter ratio (Sa). The error equations are developed, the influence of differential transmission is studied and different laser sources are considered in the analysis. The results indicate that the temperature functions become significant when using narrowband detection. Errors of 5% and more can be introduced in the water vapor mixing ratio calculation at high altitudes and errors larger than 10% are possible for calculations of aerosol scattering ratio and thus aerosol backscatter coefficient and extinction to backscatter ratio.

Whiteman, David N.

2003-01-01

17

Combined raman elastic-backscatter LIDAR for vertical profiling of moisture, aerosol extinction, backscatter, and LIDAR ratio  

Microsoft Academic Search

A combined Raman elastic-backscatter lidar has been developed. A XeCl excimer laser is used as the radiation source. Inelastic Raman backscatter signals are spectrally separated from the elastic signal with a filter or grating polychromator. Raman channels can be chosen to register signals from CO2, O2, N2, and H2O. Algorithms for the calculation of the water-vapor mixing ratio from the

A. Ansmann; M. Riebesell; U. Wandinger; C. Weitkamp; E. Voss; W. Lahmann; W. Michaelis

1992-01-01

18

Aerosol and Water Vapor Raman Lidar System at CEILAP, Buenos Aires, Argentina. Case Study: November 07, 2006.  

NASA Astrophysics Data System (ADS)

A multiwavelength backscatter LIDAR (Light Detection And Ranging) was developed and operates at Centro de Investigaciones en Láseres y Aplicaciones, CEILAP (CITEFA-CONICET), (34.5 S and 58.5 W) to study the atmospheric properties such as the aerosol optical parameters, the boundary layer evolution, and the water vapor vertical distribution. The emission system is based on a Nd:YAG laser emitting at the fundamental, second and third harmonic wavelengths. The reception unit was upgraded to collect the atmospheric elastic and nitrogen Raman backscatters from the second and third harmonic wavelength and the water vapor Raman backscatter from the third harmonic wavelength. The information from all these channels give us enough information to derive the vertical distribution of the total to molecular backscatter, the backscatter to extinction ratio (lidar ratio) and the Ångström coefficient. In addition, water vapor mixing ratio profile is also measured by using the Raman water vapor and nitrogen channels (408 and 387 nm).

Otero, Lidia Ana; Ristori, Pablo Roberto; Quel, Eduardo Jaime

2008-04-01

19

One-year aerosol profiling with EUCAARI Raman lidar at Shangdianzi GAW station: Beijing plume and seasonal variations  

NASA Astrophysics Data System (ADS)

The study examines seasonal and air-flow-dependent variations of the vertical distribution of aerosols at the Global Atmospheric Watch (GAW) station of Shangdianzi in the North China Plain 100 km northeast of Beijing. One-year Raman lidar observations of profiles of aerosol extinction and backscatter coefficients at 532 nm were performed from April 2009 to March 2010 in the framework of the European Aerosol Cloud Climate and Air Quality Interactions (EUCAARI) project. In the nighttime statistics a two-layer structure with the main haze layer reaching to 1-1.5 km height asl and an elevated aerosol layer on top with a top height of 2.5-5 km height asl was generally observed. A case study of a Beijing haze plume is presented to document the drastic changes in the environmental conditions over the background monitoring station during the passage of a strong haze front. Aerosol optical depth (AOD) and extinction coefficients increased from 0.2 to 1.2 and from 200 Mm-1 to 1000 Mm-1, respectively, within less than two hours. The statistical analysis revealed layer mean extinction coefficients of the haze layer most frequently from 200-600 Mm-1 and typically from 50-100 Mm-1in the elevated layer. The AOD ranged from about 0.3 for northerly air flows to, on average, 0.95 during southerly air flows. The lidar ratio shows a narrow distribution peaking at 60 sr in the haze layer caused by anthropogenic fine-mode aerosol and a broad distribution from 40-90 sr in the elevated layer caused by the complex mixture of aged desert dust, biomass burning smoke, and industrial pollution over eastern Asia.

HäNel, A.; Baars, H.; Althausen, D.; Ansmann, A.; Engelmann, R.; Sun, J. Y.

2012-07-01

20

In-situ, sunphotometer and Raman lidar observations of aerosol transport events in the western Mediterranean during the June 2013 ChArMEx campaign  

NASA Astrophysics Data System (ADS)

We present a preliminary analysis of aerosol observations performed in June 2013 in the western Mediterranean at two stations set up in Barcelona and Menorca (Spain) in the framework of the ChArMEx (Chemistry Aerosol Mediterranean Experiment) project. The Barcelona station was equipped with the following fixed instruments belonging to the Universitat Politècnica de Catalunya (UPC): an AERONET (Aerosol Robotic Network) sun-photometer, an MPL (Micro Pulse Lidar) lidar and the UPC multi-wavelength lidar. The MPL lidar works at 532 nm and has a depolarization channel, while the UPC lidar works at 355, 532 and 1064 nm, and also includes two N2- (at 387 and 607 nm) and one H2O-Raman (at 407 nm) channels. The MPL system works continuously 24 hour/day. The UPC system was operated on alert in coordination with the research aircrafts plans involved in the campaign. In Cap d'en Font, Menorca, the mobile laboratory of the Laboratoire des Sciences du Climat et de l'Environnement hosted an automated (AERONET) and a manual (Microtops) 5-lambda sunphotometer, a 3-lambda nephelometer, a 7-lambda aethalometer, as well as the LSCE Water vapor Aerosol LIdar (WALI). This mini Raman lidar, first developed and validated for the HyMEX (Hydrological cycle in the Mediterranean eXperiment) campaign in 2012, works at 355 nm for eye safety and is designed with a short overlap distance (<300m) to probe the lower troposphere. It includes depolarization, N2- and H2O-Raman channels. H2O observations have been calibrated on-site by different methods and show good agreement with balloon measurements. Observations at Cap d'en Font were quasi-continuous from June 10th to July 3rd, 2013. The lidar data at both stations helped direct the research aircrafts and balloon launches to interesting plumes of particles in real time for in-situ measurements. Among some light pollution background from the European continent, a typical Saharan dust event and an unusual American dust/biomass burning event are highlighted in our measurements. The lidar ratio, depolarization ratio and water content, as well as the usual aerosol vertical distribution and extinction properties provided by the Raman lidars, and the size distributions provided by AERONET, prove very helpful in characterizing particle types and sources, especially for the multi-layer situations observed. Further on, the study of parameters extracted during this campaign will allow us an assessment of the local direct aerosol radiative forcing.

Totems, Julien; Sicard, Michael; Bertolin, Santi; Boytard, Mai-Lan; Chazette, Patrick; Comeron, Adolfo; Dulac, Francois; Hassanzadeh, Sahar; Lange, Diego; Marnas, Fabien; Munoz, Constantino; Shang, Xiaoxia

2014-05-01

21

Record heavy mineral dust outbreaks over Korea in 2010: Two cases observed with multiwavelength aerosol/depolarization/Raman-quartz lidar  

NASA Astrophysics Data System (ADS)

We report on two strong events of transport of mineral dust from Central Asia across Korea. The events took place in March and November 2010. The November case is important as fall is not a typical time for strong dust outbreaks in East Asia. We observed the dust with a multiwavelength aerosol/depolarization/Raman quartz lidar. The record PM-10 concentration of nearly 1600 ?g/m3 in March 2010 exceeds the record value of 1470 ?g/m3 measured in Seoul in March 2002. The event in November was the strongest case of dust transport ever observed over Korea in fall. We find up to 360 ?g/m3 dust in heights above 250 m which is significantly different from the ground-based PM-10 observations.

Tatarov, B.; Müller, D.; Noh, Y.-M.; Lee, K.-H.; Shin, D.-H.; Shin, S.-K.; Sugimoto, N.; Seifert, P.; Kim, Y.-J.

2012-07-01

22

Vertical profiling of Asian dust with multi-wavelength aerosol depolarization Raman lidar in Gwangju, Korea during DRAGON  

NASA Astrophysics Data System (ADS)

The Distributed Regional Aerosol Gridded Observation Networks (DRAGON) campaign, which was carried out in Korea from March to May 2013, aimed at validating satellite remote sensing data of aerosol optical and microphysical parameters. Anthropogenic pollution and Asian dust from the East Asian Mainland prevailed over the Korean peninsula during the DRAGON campaign. Validation of the data products requires knowledge on the vertical distribution of aerosol pollution and the knowledge of aerosol types, e.g., urban haze and dust. For this purpose we operated a multi-wavelength aerosol depolarization Raman lidar on the campus of the Gwangju Institute of Science and Technology (GIST) in Gwangju, Korea (35.10° N, 126.53° E). The system provides us with particle backscatter coefficients at 355, 532 and 1064 nm, extinction coefficients at 355 and 532nm, and the linear particle depolarization ratio at 532nm. Two upgraded sun photometers of the Aerosol Robotic Network (AERONET) with improved capabilities for dust measurements were also deployed. In our contribution we will present optical properties of Asian dust on the basis of lidar and sun photometer observations. One sun photometer was equipped with a measurement channel at 1640 nm channel and the second sun photometer carried out polarization measurements. Data could be collected on thirty-eight days We analyzed the geometrical and optical properties of Asian dust on the basis of backward trajectories in order to identify the main source regions of the observed dust layers. The height resolved statistical analysis of the DRAGON dataset reveals that the geometrical depth of the Asian dust layers was between 1 km and 4 km in 72% of all cases. Geometrical depths above 4 km were found in 20% of all cases. We found geometrical depths of 10 km in 3.3% of all cases. The vertical distribution of the dust layers was typically located in two different heights. In 51.5% of the measurements we observed Asian dust between 4 and 11km height above sea level. In 48.5% of the cases dust was below 4 km height above sea level.

Shin, D.; Mueller, D.; Noh, Y.; Shin, S.; Kim, Y. J.

2013-12-01

23

Advanced Raman water vapor lidar  

NASA Technical Reports Server (NTRS)

Water vapor and aerosols are important atmospheric constituents. Knowledge of the structure of water vapor is important in understanding convective development, atmospheric stability, the interaction of the atmosphere with the surface, and energy feedback mechanisms and how they relate to global warming calculations. The Raman Lidar group at the NASA Goddard Space Flight Center (GSFC) developed an advanced Raman Lidar for use in measuring water vapor and aerosols in the earth's atmosphere. Drawing on the experience gained through the development and use of our previous Nd:YAG based system, we have developed a completely new lidar system which uses a XeF excimer laser and a large scanning mirror. The additional power of the excimer and the considerably improved optical throughput of the system have resulted in approximately a factor of 25 improvement in system performance for nighttime measurements. Every component of the current system has new design concepts incorporated. The lidar system consists of two mobile trailers; the first (13m x 2.4m) houses the lidar instrument, the other (9.75m x 2.4m) is for system control, realtime data display, and analysis. The laser transmitter is a Lambda Physik LPX 240 iCC operating at 400 Hz with a XeF gas mixture (351 nm). The telescope is a .75m horizontally mounted Dall-Kirkham system which is bore sited with a .8m x 1.1m elliptical flat which has a full 180 degree scan capability - horizon to horizon within a plane perpendicular to the long axis of the trailer. The telescope and scan mirror assembly are mounted on a 3.65m x .9m optical table which deploys out the rear of the trailer through the use of a motor driven slide rail system. The Raman returns from water vapor (403 nm), nitrogen (383 nm) and oxygen (372 nm) are measured in addition to the direct Rayleigh/Mie backscatter (351). The signal from each of these is split at about a 5/95 ratio between two photomultiplier detectors. The 5 percent detector is used for measurements below about 4.0 km, while the 95 percent detector provides the information above this level.

Whiteman, David N.; Melfi, S. Harvey; Ferrare, Richard A.; Evans, Keith A.; Ramos-Izquierdo, Luis; Staley, O. Glenn; Disilvestre, Raymond W.; Gorin, Inna; Kirks, Kenneth R.; Mamakos, William A.

1992-01-01

24

Turn-key Raman lidar for profiling atmospheric water vapor, clouds, and aerosols at the US Southern Great Plains Climate Study Site  

SciTech Connect

There are clearly identified scientific requirements for continuous profiling of atmospheric water vapor at the Department of Energy, Atmospheric Radiation Measurement program, Southern Great Plains CART (Cloud and Radiation Testbed) site in northern Oklahoma. Research conducted at several laboratories has demonstrated the suitability of Raman lidar for providing measurements that are an excellent match to those requirements. We have developed and installed a ruggedized Raman lidar system that resides permanently at the CART site, and that is computer automated to eliminate the requirements for operator interaction. In addition to the design goal of profiling water vapor through most of the troposphere during nighttime and through the boundary layer during daytime, the lidar provides quantitative characterizations of aerosols and clouds, including depolarization measurements for particle phase studies.

Goldsmith, J.E.M.; Blair, F.H.; Bisson, S.E.

1997-12-31

25

Airborne Raman lidar  

NASA Astrophysics Data System (ADS)

We designed and tested an airborne lidar system using Raman scattering to make simultaneous measurements of methane, water vapor, and temperature in a series of flights on a NASA-operated C-130 aircraft. We present the results for methane detection, which show that the instrument has the requisite sensitivity to atmospheric trace gases. Ultimately these measurements can be used to examine the transport of chemically processed air from within the polar vortex to mid-latitudinal regions and the exchange of stratospheric air between tropical and mid-latitudinal regions.

Heaps, Wm. S.; Burris, J.

1996-12-01

26

Airborne Raman lidar.  

PubMed

We designed and tested an airborne lidar system using Raman scattering to make simultaneous measurements of methane, water vapor, and temperature in a series of flights on a NASA-operated C-130 aircraft. We present the results for methane detection, which show that the instrument has the requisite sensitivity to atmospheric trace gases. Ultimately these measurements can be used to examine the transport of chemically processed air from within the polar vortex to mid-latitudinal regions and the exchange of stratospheric air between tropical and mid-latitudinal regions. PMID:21151318

Heaps, W S; Burris, J

1996-12-20

27

Arrange and average algorithm for the retrieval of aerosol parameters from multiwavelength high-spectral-resolution lidar/Raman lidar data.  

PubMed

We present the results of a feasibility study in which a simple, automated, and unsupervised algorithm, which we call the arrange and average algorithm, is used to infer microphysical parameters (complex refractive index, effective radius, total number, surface area, and volume concentrations) of atmospheric aerosol particles. The algorithm uses backscatter coefficients at 355, 532, and 1064 nm and extinction coefficients at 355 and 532 nm as input information. Testing of the algorithm is based on synthetic optical data that are computed from prescribed monomodal particle size distributions and complex refractive indices that describe spherical, primarily fine mode pollution particles. We tested the performance of the algorithm for the "3 backscatter (?)+2 extinction (?)" configuration of a multiwavelength aerosol high-spectral-resolution lidar (HSRL) or Raman lidar. We investigated the degree to which the microphysical results retrieved by this algorithm depends on the number of input backscatter and extinction coefficients. For example, we tested "3?+1?," "2?+1?," and "3?" lidar configurations. This arrange and average algorithm can be used in two ways. First, it can be applied for quick data processing of experimental data acquired with lidar. Fast automated retrievals of microphysical particle properties are needed in view of the enormous amount of data that can be acquired by the NASA Langley Research Center's airborne "3?+2?" High-Spectral-Resolution Lidar (HSRL-2). It would prove useful for the growing number of ground-based multiwavelength lidar networks, and it would provide an option for analyzing the vast amount of optical data acquired with a future spaceborne multiwavelength lidar. The second potential application is to improve the microphysical particle characterization with our existing inversion algorithm that uses Tikhonov's inversion with regularization. This advanced algorithm has recently undergone development to allow automated and unsupervised processing; the arrange and average algorithm can be used as a preclassifier to further improve its speed and precision. First tests of the performance of arrange and average algorithm are encouraging. We used a set of 48 different monomodal particle size distributions, 4 real parts and 15 imaginary parts of the complex refractive index. All in all we tested 2880 different optical data sets for 0%, 10%, and 20% Gaussian measurement noise (one-standard deviation). In the case of the "3?+2?" configuration with 10% measurement noise, we retrieve the particle effective radius to within 27% for 1964 (68.2%) of the test optical data sets. The number concentration is obtained to 76%, the surface area concentration to 16%, and the volume concentration to 30% precision. The "3?" configuration performs significantly poorer. The performance of the "3?+1?" and "2?+1?" configurations is intermediate between the "3?+2?" and the "3?." PMID:25402885

Chemyakin, Eduard; Müller, Detlef; Burton, Sharon; Kolgotin, Alexei; Hostetler, Chris; Ferrare, Richard

2014-11-01

28

Aerosol lidar ``M4``  

SciTech Connect

Small carrying aerosol lidar in which is used small copper vapor laser ``Malachite`` as source of sounding optical pulses is described. The advantages of metal vapor laser and photon counting mode in acquisition system of lidar gave ability to get record results: when lidar has dimensions (1 x .6 x .3 m) and weight (65 kg), it provides the sounding of air industrial pollutions at up to 20 km range in scanning sector 90{degree}. Power feed is less than 800 Wt. Lidar can be disposed as stationary so on the car, helicopter, light plane. Results of location of smoke tails and city smog in situ experiments are cited. Showed advantages of work of acquisition system in photon counting mode when dynamic range of a signal is up to six orders.

Shelevoy, C.D.; Andreev, Y.M. [Super Computer Devices Co. Ltd., Tomsk (Russian Federation); [Siberian State Medical Univ., Tomsk (Russian Federation)

1994-12-31

29

Operational detection of aerosols by the calibrated RAman LIDAR for Meteorological Observation (RALMO) and the CHM15K ceilometer at Payerne, Switzerland  

NASA Astrophysics Data System (ADS)

Ceilometers have become increasingly present across the globe at airports, national meteorological Services and research centers. More sophisticated LIDARs based on both elastic and inelastic scattering principles are currently available at several national research institutions and meteorological services. A growing need to optimize the generation of real-time data from these Automatic LIDARs and ceilometers (ALC) is also proven by new European programmes aiming at integrating a significant number of ALC instruments into large networks (e.g. E-PROFILE, http://www.eumetnet.eu/e-profile). The use of ALC instruments for operational detection of aerosols and clouds is submitted to their cost effectiveness as well as to the availability of scientific expertise for data monitoring and interpretation. Essential for data use and interpretation is the calibration procedure aimed to provide system-independent LIDAR products. An example of data calibration for backscatter and extinction coefficient measured with an automated RAman LIDAR (RALMO) and a CHM15K ceilometer will be presented. The temporal and vertical stability of the incomplete overlap correction function and of the Rayleigh calibration constant have been studied for both systems. Two cases of detection of long-range transported aerosol, from Canadian biomass burning and Saharan dust by the two calibrated systems will also be presented.

Martucci, Giovanni; Haefele, Alexander; Calpini, Bertrand; Simeonov, Valentin

2014-05-01

30

Raman lidar observations of cloud liquid water.  

PubMed

We report the design and the performances of a Raman lidar for long-term monitoring of tropospheric aerosol backscattering and extinction coefficients, water vapor mixing ratio, and cloud liquid water. We focus on the system's capabilities of detecting Raman backscattering from cloud liquid water. After describing the system components, along with the current limitations and options for improvement, we report examples of observations in the case of low-level cumulus clouds. The measurements of the cloud liquid water content, as well as the estimations of the cloud droplet effective radii and number densities, obtained by combining the extinction coefficient and cloud water content within the clouds, are critically discussed. PMID:15617280

Rizi, Vincenzo; Iarlori, Marco; Rocci, Giuseppe; Visconti, Guido

2004-12-10

31

Ultraviolet scanning Raman lidar with fast telescope for measurements of water vapor and aerosols in lower atmosphere  

NASA Astrophysics Data System (ADS)

This work reports on the design, construction and commissioning of a ultraviolet scanning Raman lidar system, which is deployed at the Otlica observatory in Slovenia. The system uses a fast parabolic mirror as a receiver and a frequency-tripled Q-Switched Nd:YAG pulsed laser as a transmitter, both are mounted on a common frame with steerable elevation angle. Custom optics using a low f-number aspheric lens were designed to focus the light into a UV-enhanced optical ber, used to transfer the lidar return signal from the telescope to the polychromator. Vibrational Raman spectra of N2 and H2O were separated using narrow-band interference lters combined with dichroic beam splitters. System functionality and performance was assessed in a series of preliminary experiments and by the comparison of the retrieved results to radiosonde data.

Gao, F.; Stanic, S.; He, T.-Y.; Hua, D.-X.

2012-06-01

32

YAG aerosol lidar  

NASA Technical Reports Server (NTRS)

The Global Atmospheric Backscatter Experiment (GLOBE) Mission, using the NASA DC-8 aircraft platform, is designed to provide the magnitude and statistical distribution of atmospheric backscatter cross section at lidar operating wavelengths. This is a fundamental parameter required for the Doppler lidar proposed to be used on a spacecraft platform for global wind field measurements. The prime measurements will be made by a CO2 lidar instrument in the 9 to 10 micron range. These measurements will be complemented with the Goddard YAG Aerosol Lidar (YAL) data in two wavelengths, 0.532 and 1.06 micron, in the visible and near-infrared. The YAL, is being designed to utilize as much existing hardware, as feasible, to minimize cost and reduce implementation time. The laser, energy monitor, telescope and detector package will be mounted on an optical breadboard. The optical breadboard is mounted through isolation mounts between two low boy racks. The detector package will utilize a photomultiplier tube for the 0.532 micron channel and a silicon avalanche photo detector (APD) for the 1.06 micron channel.

Sullivan, R.

1988-01-01

33

[Raman Lidar measuring tropospheric temperature profiles with many rotational Raman lines].  

PubMed

Due to lower tropospheric aerosols, the Rayleigh and vibrational Raman methods can't measure lower tropospheric temperature profiles accurately. By using N2 and O2 molecular pure rotational Raman scattering signals, lower tropospheric temperature profiles can be gained without influence of lower tropospheric aerosols. So we decide to use a pure rotational Raman Lidar to get lower tropospheric temperature profiles. At present, because the most light-splitting systems of pure rotational Raman Lidar measure temperature by gaining a single rotational Raman line, the signal to noise ratio (SNR) of these Lidar systems are very low. So we design a new kind of Lidar light-splitting system which can sum different rotational Raman lines and it can improve SNR And we can find the sensitivity of the temperature of the ratios of multi rotational Raman lines is as same as single rotational Raman line's through theoretical analysis. Moreover, we can obtain the temperature profiles with good SNR fromthis new the system with a normal laser and a small telescope up to several kilometers. At last, with the new light-splitting system, the lower tropospheric temperature profiles are measured from 0.3 km to 5 km altitude. They agree well with radiosonde observations, which demonstrate the results of our rotational Raman lidar are reasonable. PMID:18975802

Su, Jia; Zhang, Yin-chao; Hu, Shun-xing; Cao, Kai-fa; Zhao, Pei-tao; Wang, Shao-lin; Xie, Jun

2008-08-01

34

What Good is Raman Water Vapor Lidar?  

NASA Technical Reports Server (NTRS)

Raman lidar has been used to quantify water vapor in the atmosphere for various scientific studies including mesoscale meteorology and satellite validation. Now the international networks of NDACC and GRUAN have interest in using Raman water vapor lidar for detecting trends in atmospheric water vapor concentrations. What are the data needs for addressing these very different measurement challenges. We will review briefly the scientific needs for water vapor accuracy for each of these three applications and attempt to translate that into performance specifications for Raman lidar in an effort to address the question in the title of "What good is Raman water vapor Iidar."

Whitman, David

2011-01-01

35

Development of a Raman lidar simulation tool  

NASA Technical Reports Server (NTRS)

Raman Lidar is a useful and powerful tool for remote probing of the atmosphere. With Raman Lidars, one can accurately determine the identity and concentration of a particular molecular specie present in the atmosphere. We present the results from a program to develop a simulation capability of Raman Lidar systems for the remote detection of atmospheric gases and/or air polluting hydrocarbons. Our model, which integrates remote Raman spectroscopy with SPARTA's BACKSCAT atmospheric lidar simulation package, permits accurate determination of the performance of a Raman Lidar system. The accuracy with which our model operates is due to the accurate calculation, at any given excitation wavelength, of the differential scattering cross section for the molecular specie under investigation. We show excellent correlation of our calculated cross section data with experimental data from the published literature. In addition, the use of our BACKSCAT package, which provides a user friendly environment to define the operating conditions, provides an accurate calculation of the atmospheric extinction at both the excitation and Raman shifted wavelengths. Our code can be used to accurately predict the performance of a Raman Lidar system, the concentration and identification of a specie in the atmosphere, or the feasibility of making Raman measurements.

Grasso, R. J.; Hummel, J. R.

1992-01-01

36

Development of a Raman lidar simulation tool  

NASA Astrophysics Data System (ADS)

Raman Lidar is a useful and powerful tool for remote probing of the atmosphere. With Raman Lidars, one can accurately determine the identity and concentration of a particular molecular specie present in the atmosphere. We present the results from a program to develop a simulation capability of Raman Lidar systems for the remote detection of atmospheric gases and/or air polluting hydrocarbons. Our model, which integrates remote Raman spectroscopy with SPARTA's BACKSCAT atmospheric lidar simulation package, permits accurate determination of the performance of a Raman Lidar system. The accuracy with which our model operates is due to the accurate calculation, at any given excitation wavelength, of the differential scattering cross section for the molecular specie under investigation. We show excellent correlation of our calculated cross section data with experimental data from the published literature. In addition, the use of our BACKSCAT package, which provides a user friendly environment to define the operating conditions, provides an accurate calculation of the atmospheric extinction at both the excitation and Raman shifted wavelengths. Our code can be used to accurately predict the performance of a Raman Lidar system, the concentration and identification of a specie in the atmosphere, or the feasibility of making Raman measurements.

Grasso, R. J.; Hummel, J. R.

1992-07-01

37

Status and motivation of Raman LIDARs development for the CTA Observatory  

E-print Network

The Cherenkov Telescope Array (CTA) is the next generation of Imaging Atmospheric Cherenkov Telescopes. It would reach unprecedented sensitivity and energy resolution in very-high-energy gamma-ray astronomy. In order to reach these goals, the systematic uncertainties derived from the varying atmospheric conditions shall be reduced to the minimum. Different instruments may help to account for these uncertainties. Several groups in the CTA consortium are currently building Raman LIDARs to be installed at the CTA sites. Raman LIDARs are devices composed of a powerful laser that shoots into the atmosphere, a collector that gathers the backscattered light from molecules and aerosols, a photosensor, an optical module that spectrally select wavelengths of interest, and a read-out system. Raman LIDARs can reduce the systematic uncertainties in the reconstruction of the gamma-ray energies down to 5 % level. All Raman LIDARs subject of this work, have design features that make them different than typical Raman LIDARs u...

Doro, M; Pallotta, J; Vasileiadis, G; Blanch, O; Chouza, F; D'Elia, R; Etchegoyen, A; Font, Ll; Garrido, D; Gonzales, F; López-Oramas, A; Martínez, M; Otero, L; Quel, E; Ristori, P

2014-01-01

38

Aerosol backscatter lidar calibration and data interpretation  

NASA Technical Reports Server (NTRS)

A treatment of the various factors involved in lidar data acquisition and analysis is presented. This treatment highlights sources of fundamental, systematic, modeling, and calibration errors that may affect the accurate interpretation and calibration of lidar aerosol backscatter data. The discussion primarily pertains to ground based, pulsed CO2 lidars that probe the troposphere and are calibrated using large, hard calibration targets. However, a large part of the analysis is relevant to other types of lidar systems such as lidars operating at other wavelengths; continuous wave (CW) lidars; lidars operating in other regions of the atmosphere; lidars measuring nonaerosol elastic or inelastic backscatter; airborne or Earth-orbiting lidar platforms; and lidars employing combinations of the above characteristics.

Kavaya, M. J.; Menzies, R. T.

1984-01-01

39

Experimental determination of Raman lidar geometric form factor combining Raman and elastic return  

NASA Astrophysics Data System (ADS)

A straightforward method is presented for the determination of the geometric form factor in Raman-Mie lidar by using elastic backscatter signal from different altitudes and derived particle backscatter coefficients. The theory is briefly described. The error of this method is discussed and a comparison with the method proposed by Wandinger and Ansmann indicates the improved accuracy of the new method. The effect of the determined geometric form factor error on aerosol extinction coefficient retrieval is further discussed. The results of the experiment show that the derived aerosol extinction coefficient profile is less affected by the geometric form factor error when the atmospheric aerosol concentration is higher.

Chen, Hao; Chen, Siying; Zhang, Yinchao; Chen, He; Guo, Pan; Chen, Binglong

2014-12-01

40

The mobile Water vapor Aerosol Raman LIdar and its implication in the framework of the HyMeX and ChArMEx programs: application to a dust transport process  

NASA Astrophysics Data System (ADS)

The increasing importance of the coupling of water and aerosol cycles in environmental applications requires observation tools that allow simultaneous measurements of these two fundamental processes for climatological and meteorological studies. For this purpose, a new mobile Raman lidar, WALI (Water vapor and Aerosol LIdar), has been developed and implemented within the framework of the international HyMeX and ChArMEx programs. This paper presents the key properties of this new device and its first applications to scientific studies. The lidar uses an eye-safe emission in the ultraviolet range at 354.7 nm and a set of compact refractive receiving telescopes. Cross-comparisons between rawinsoundings performed from balloon or aircraft and lidar measurements have shown a good agreement in the derived water vapor mixing ratio (WVMR). The discrepancies are generally less than 0.5 g kg-1 and therefore within the error bars of the respective instruments. A detailed study of the uncertainty of the WVMR retrieval was conducted and shows values between 7 and 11%, which is largely constrained by the quality of the lidar calibration. It also proves that the lidar is able to measure the WVMR during daytime over a range of about 1 km. In addition the WALI system provides measurements of aerosol optical properties such as the lidar ratio (LR) or the particulate depolarization ratio (PDR). An important example of scientific application addressing the main objectives of the HyMeX and ChArMEx programs is then presented, following an event of desert dust aerosols over the Balearic Islands in October 2012. This dust intrusion may have had a significant impact on the intense precipitations that occurred over southwestern France and the Spanish Mediterranean coasts. During this event, the LR and PDR values obtained are in the ranges of ~45-63 ± 6 and 0.10-0.19 ± 0.01 sr, respectively, which is representative of dust aerosols. The dust layers are also shown to be associated with significant WVMR, i.e., between 4 and 6.7 g kg-1.

Chazette, P.; Marnas, F.; Totems, J.

2014-06-01

41

Airborne lidar studies of air aerosol pollution  

SciTech Connect

Aerosol number concentrations in Aral Sea region were measured by airborne ruby lidar. Traditional lidar technique was used. The unconventional airborne lidar techniques have been developed. These techniques are based on new solutions of lidar equation found to invert it without traditional {open_quotes}a priori{close_quotes} assumptions. They assume that investigated atmospheric volume is sounded by lidar system transmitting pulses along different directions. Two ruby lidars transmitting pulses along opposite directions were installed on board the aircraft and optical parameters of the atmosphere in Arctic were obtained. 10 refs., 2 tabs.

Yegorov, A.D. [Voeikov MGO Research Center for Atmospheric Remote Sensing, St. Petersburg (Russian Federation)

1996-10-01

42

Advanced Aerosol Lidar Ratio Determination Algorithms Using Aerosol Covariance Models  

NASA Astrophysics Data System (ADS)

We present an algorithm to determine the extinction to backscatter (lidar) ratio (Sa), an important parameter used in the determination of the aerosol extinction and subsequently the optical depth from lidar backscatter measurements. This scheme applies to Sa determination at 532 nm and 1064 nm for a space-based two-wavelength lidar such as CALIOP on the Cloud and Aerosol Lidar and Infrared Pathfinder Spaceborne Observations (CALIPSO) satellite. The algorithm applies the Mahalanobis distance to CALIOP measurements of backscatter and depolarization and initial estimates of Sa at both wavelengths to identify the most likely aerosol model from a family of a priori probability distributions of lidar ratio, backscatter and depolarization determined from previously generated classification of High Spectral Resolution Lidar (HSRL) aerosol measurements. The HSRL record includes aerosol type specific distributions of Sa at 532 nm. We use auxiliary measurements of pairs of 532 nm and 1064 nm Sa for Urban, Smoke, Marine, and Dust aerosols from AERONET and field measurements, the NASA African Monsoon Multidisciplinary Analyses (NAMMA) and Shoreline Environmental Aerosol Study (SEAS), to develop piecewise covariance matrices using the HSRL distributions of these four aerosol types. Covariance matrices including lidar ratio at both wavelengths can also be obtained through the Enhanced Constrained Ratio Aerosol Method (E-CRAM) applied to HSRL data. We explore the application of the aerosol model matching method to CALIOP data and compare the results with HSRL 532 nm Sa distributions for coincident flights.

Hostetler, C. A.; Omar, A. H.; Burton, S. P.; Vaughan, M.; Rogers, R.; Ferrare, R. A.; Reagan, J. A.; McPherson, C.

2011-12-01

43

Studying Taklamakan aerosol properties with lidar (STAPL)  

NASA Astrophysics Data System (ADS)

By now, the global impacts of atmospheric dust have been well-established. Nevertheless, relevant properties such as size distribution, depolarization ratio, and even single-scattering albedo have been shown to vary substantially between dust producing regions and are also strongly dependant on the conditions under which the dust is emitted. Even greater variations have been documented during the process of long-range transport. With continued improvement of detection technologies, research focus is increasingly turning to refinement of our knowledge of these properties of dust in order to better account for the presence of dust in models and data analysis. The purpose of this study is to use a combination of lidar data and models to directly observe the changing properties of dust layers as they are transported from their origin in the Taklamakan Desert of western China. With the co-operation of the Xinjiang Institute of Ecology and Geography, a portable micropulse lidar system was installed at Aksu National Field on the northern edge of the Tarim Basin in late April 2013, during the Spring dust storm season. Over six days, data were collected on the optical properties of dust emissions passing over this location. The measurements of this lidar have shown the dust over Aksu on these days to have a significantly higher depolarization ratio than has been previously reported for the region. Model results show this dust was then transported across the region at least as far as Korea and Japan. Models from the Naval Aerosol Analysis and Prediction System (NAAPS) show that during transport the dust layers became intermixed with sulfate emissions from industrial sources in China as well as smoke from wildfires burning in south-east Asia and Siberia. The multi-wavelength raman-elastic lidar located in Gwangju South Korea was used to observe the vertical structure of the layers as well as optical properties such as colour ratio, depolarization ratio and extinction coeffcient after regional-scale transportation and mixing with other aerosols. By comparing the observations of the Gwangju lidar with those taken near the source at Aksu, we investigate the extent of the change in optical properties of the dust layers over time. There is some evidence that the layers were also transported in some form to North America but these observations are preliminary and will require further investigation.

Cottle, Paul; Mueller, Detlef; Shin, Dong-Ho; Zhang, Xiao Xiao; Feng, Guanglong; McKendry, Ian; Strawbridge, Kevin

2013-10-01

44

Aerosol Classification by Advanced Backscatter Lidar Techniques  

NASA Astrophysics Data System (ADS)

The high spectral resolution lidar (HSRL) method based on an iodine absorption filter and a frequency doubled pulsed Nd:YAG laser is presented. This method has the capability to directly measure the extinction and backscatter coefficients of aerosols and clouds. Measurements of an airborne HSRL system from four different field experiments are used to build up an aerosol classification. Two examples show the potential of this aerosol classification to distinguish between different aerosol types.

Groß, Silke; Wirth, Martin; Esselborn, Michael

45

Identification of aerosol species using polarization lidar  

NASA Astrophysics Data System (ADS)

This paper presents a new approach that has been developed to identify individual aerosol species using polarization lidar measurements. Individual aerosols can be identified based on their distinct ratios of extinction to backscatter, which are related to the depolarization ratio profile. Aerosol backscatter coefficients can be obtained from these ratios. Differential aerosol backscatter coefficients are proportional to the variation of the ratio of extinction to backscatter coefficient, and the coefficients increase, reach a peak value, and then decrease again, with increasing range.

Cao, Nianwen; Zhu, Cunxiong; Yang, Shaobo; Xie, Yinhai; Yang, Fengkai; Zhang, Feng

2014-09-01

46

2, 75107, 2002 Raman lidar  

E-print Network

were restricted10 to darkness. For the climatological analysis, we selected the cloud-free days out.atmos-chem-phys.org/acpd/2/75/ c European Geophysical Society 2002 Atmospheric Chemistry and Physics Discussions Three years 2002 Abstract We have performed a three-year series of routine lidar measurements on a clima- tological

Boyer, Edmond

47

Infrared lidar observations of stratospheric aerosols.  

PubMed

We observed the stratospheric aerosol layer at 34° north latitude with a photon-counting 1574 nm lidar on three occasions in 2011. During all of the observations, we also operated a nearby 523.5 nm micropulse lidar and acquired National Weather Service upper air data. We analyzed the lidar data to find scattering ratio profiles and the integrated aerosol backscatter at both wavelengths and then calculated the color ratio and wavelength exponent for lidar backscattering from the stratospheric aerosols. The visible-light integrated backscatter values of the layer were in the range 2.8-3.5×10?? sr?¹ and the infrared integrated backscatter values ranged from 2.4 to 3.7×10????sr?¹. The wavelength exponent was determined to be 1.9±0.2. PMID:24922442

Forrister, H N; Roberts, D W; Mercer, A J; Gimmestad, G G

2014-06-01

48

Atmospheric temperature measurements, using Raman lidar  

NASA Technical Reports Server (NTRS)

The Raman-shifted return of a lidar system had been used to make atmospheric temperature measurements. The measurements were made along a horizontal path at temperatures ranging from -30 to 30 C and at ranges of about 100 meters. The temperature data were acquired by recording the intensity ratio of two portions of the rotational Raman spectrum, which were simultaneously sampled from a preset range. These tests verified that the theoretical predictions formulated in the design of the system were adequate. Measurements were made to an accuracy of + or - 4 C with 1-minute temporal resolution.

Salzman, J. A.; Coney, T. A.

1974-01-01

49

The vertical distribution of aerosol over Europe—synthesis of one year of EARLINET aerosol lidar measurements and aerosol transport modeling with LMDzT-INCA  

Microsoft Academic Search

Aerosol extinction vertical profiles measured with Raman lidar in the framework of EARLINET in 2000 are compared to profiles modeled by a general circulation model, LMDzT-INCA, at seven stations in Europe. Comparisons based on individual profiles show moderate correlation between model and data. Averaging aerosol extinction values on larger temporal or spatial scales improves the comparison. Furthermore, we show that

Sarah Guibert; Volker Matthias; Michael Schulz; Jens Bösenberg; Ronald Eixmann; Ina Mattis; Gelsomina Pappalardo; Maria Rita Perrone; Nicola Spinelli; Geraint Vaughan

2005-01-01

50

Characterization of Saharan dust, marine aerosols and mixtures of biomass-burning aerosols and dust by means of multi-wavelength depolarization and Raman lidar measurements during SAMUM 2  

NASA Astrophysics Data System (ADS)

The particle linear depolarization ratio ?p of Saharan dust, marine aerosols and mixtures of biomass-burning aerosols from southern West Africa and Saharan dust was determined at three wavelengths with three lidar systems during the SAharan Mineral dUst experiMent 2 at the airport of Praia, Cape Verde, between 22 January and 9 February 2008. The lidar ratio Sp of these major types of tropospheric aerosols was analysed at two wavelengths. For Saharan dust, we find wavelength dependent mean particle linear depolarization ratios ?p of 0.24-0.27 at 355 nm, 0.29-0.31 at 532 nm and 0.36-0.40 at 710 nm, and wavelength independent mean lidar ratios Sp of 48-70 sr. Mixtures of biomass-burning aerosols and dust show wavelength independent values of ?p and Sp between 0.12-0.23 and 57-98 sr, respectively. The mean values of marine aerosols range independent of wavelength for ?p from 0.01 to 0.03 and for Sp from 14 to 24 sr.

Groß, Silke; Tesche, Matthias; Freudenthaler, Volker; Toledano, Carlos; Wiegner, Matthias; Ansmann, Albert; Althausen, Dietrich; Seefeldner, Meinhard

2011-09-01

51

Vertical profiling of Saharan dust with Raman lidars and airborne HSRL in southern Morocco during SAMUM  

Microsoft Academic Search

ABSTRACT Three ground-based Raman lidars and an airborne high-spectral-resolution lidar (HSRL) were operated during SAMUM 2006 in southern Morocco to measure height profiles of the volume extinction coefficient, the extinction-to-backscatter ratio and the depolarization ratio of dust particles in the Saharan dust layer at several wavelengths. Aerosol Robotic Network (AERONET) Sun photometer observations and radiosoundings of meteorological parameters complemented the

Matthias Tesche; Albert Ansmann; Detlef Müller; Dietrich Althausen; Ina Mattis; Birgit Heese; Volker Freudenthaler; Matthias Wiegner; Michael Esselborn; Gianluca Pisani; Peter Knippertz

2009-01-01

52

Vertical profiling of Saharan dust with Raman lidars and airborne HSRL in southern Morocco during SAMUM  

Microsoft Academic Search

Three ground-based Raman lidars and an airborne high-spectral-resolution lidar (HSRL) were operated during SAMUM 2006 in southern Morocco to measure height profiles of the volume extinction coefficient, the extinction-to-backscatter ratio and the depolarization ratio of dust particles in the Saharan dust layer at several wavelengths. Aerosol Robotic Network (AERONET) Sun photometer observations and radiosoundings of meteorological parameters complemented the ground-based

D IETRICH AL T HAUSEN; INA M ATTIS; V OLKER F REUDENTHALER; W IEGNER; M ICHAEL E SSELBORN; G IANLUCA P ISANI; P ETER K NIPPERTZ

2009-01-01

53

Tropical stratospheric aerosol layer from CALIPSO lidar observations  

Microsoft Academic Search

The evolution of the aerosols in the tropical stratosphere since the beginning of the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) mission in June 2006 is investigated using Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) lidar data. It is shown that the current operational calibration requires adjustment in the tropics. Indeed, on the basis of the assumption of pure Rayleigh

J. P. Vernier; J. P. Pommereau; A. Garnier; J. Pelon; N. Larsen; J. Nielsen; T. Christensen; L. W. Thomason; T. Leblanc; I. S. McDermid

2009-01-01

54

New Examination of the Traditional Raman Lidar Technique. 1; Temperature Dependence and the Calculation of Atmospheric Transmission  

NASA Technical Reports Server (NTRS)

The intent of this paper and its companion paper is to pull together the essential information required for the traditional Raman lidar data analysis to be performed. As a part of this, complications such as the temperature dependence of the water vapor signal is evaluated through numerical simulation. A new form of the lidar equation is presented that accounts for the temperature dependence of Raman scattering. Also the calculation of atmospheric transmission is examined carefully. Several photon correction techniques are considered as is the influence of multiple scattering on the measurement of aerosol extinction using the Raman lidar technique.

Whiteman, David N.; Abshire, James B. (Technical Monitor)

2002-01-01

55

Automatic gain control for Raman lidar signals  

NASA Astrophysics Data System (ADS)

Electronic component improvements allow everyone to use them for performing new features in different applications. Lidar signal control is matter of continuous design and it can be studied in order to increase signal-to-noise ratio. Fortunately, the advent, of programmable gain amplifiers, switching capacitor filters and specific AD converters, is the stimulus of improving lidar signal quality. The main scope of this paper is to design and to realize a hardware simulator capable of reproducing the behavior of lidar signal control. This paper aims at describing the results of an automatic control system for Raman lidar signals. The system is based on the following units: laser source, damper, PMT (Photomultiplier), current - to - voltage converter, switched capacitor filter, programmable gain amplifier, A/D converter and FIR filter. This configuration allows the use of FIR filter that is not strictly necessary but it can help in adapting signal according to the amplitude. One of the main advantage of this system is to obtain a flexible and programmable board.

Lay-Ekuakille, Aimé; Vendramin, Giuseppe; Trotta, Amerigo

2008-12-01

56

Advances in Raman Lidar Measurements of Water Vapor  

NASA Technical Reports Server (NTRS)

Recent technology upgrades to the NASA/GSFC Scanning Raman Lidar have permitted significant improvements in the daytime and nighttime measurement of water vapor using Raman lidar. Numerical simulation has been used to study the temperature sensitivity of the narrow spectral band measurements presented here.

Whiteman, D. N.; Evans, K.; Demoz, B.; DiGirolamo, P.; Mielke, B.; Stein, B.; Goldsmith, J. E. M.; Tooman, T.; Turner, D.; Starr, David OC. (Technical Monitor)

2002-01-01

57

Airborne High Spectral Resolution Lidar Measurements of Atmospheric Aerosols  

Microsoft Academic Search

NASA Langley Research Center (LaRC) recently developed an airborne High Spectral Resolution Lidar (HSRL) to measure aerosol distributions and optical properties. The HSRL technique takes advantage of the spectral distribution of the lidar return signal to discriminate aerosol and molecular signals and thereby measure aerosol extinction and backscatter independently. The LaRC instrument employs the HSRL technique to measure aerosol backscatter

R. Ferrare; C. Hostetler; J. Hair; A. Cook; D. Harper; L. Kleinman; A. Clarke; P. Russell; J. Redemann; J. Livingston; J. Szykman; J. Al-Saadi

2007-01-01

58

Towards an aerosol classification scheme for EarthCARE lidar observations  

NASA Astrophysics Data System (ADS)

Aerosols are a major component of the Earth's atmosphere and have substantial impact on the Earth's radiation budget and on the hydrological cycle. The distribution of aerosols and their microphysical and optical properties vary strongly with space and time. Furthermore the vertical distribution of aerosols and the presence of clouds affect the sign and magnitude of the aerosol radiative forcing. To improve our knowledge about the climate impact of aerosols regular observations with high temporal and vertical resolution are required. Space borne lidar measurements are an appropriate tool to obtain altitude resolved information of the aerosol distribution on global scale. However, an aerosol classification from current space borne lidar measurements is only possible with further assumptions. The next generation satellite mission of the European Space Agency, the Earth Clouds, Aerosols and Radiation Explorer (EarthCARE) mission, expected for launch in 2015, will be equipped with a polarization sensitive high spectral resolution lidar (HSRL) system operating at 355 nm (ATLID - Atmospheric Lidar). The potential of polarization sensitive HSRL measurements for aerosol type classification was demonstrated on the basis of airborne HSRL measurements. However, these airborne measurements were performed at 532 nm. The open question is how the results of these HSRL classification schemes at 532 nm can be transferred to measurements at 355 nm with ATLID on EarthCARE. We will present an analysis of the wavelength dependence of the optical properties required for an aerosol type classification based on ATLID measurements, the particle linear depolarization ratio and the particle lidar ratio. For this analysis we use ground based measurements of polarization sensitive Raman lidar systems at 355 nm and 532 nm and airborne HSRL measurements at 532 nm. Furthermore we use model simulations of the lidar-relevant optical properties of different aerosol types taking into account their particle shapes. Airborne in-situ measurements of the size distribution and refractive index of several aerosol types are used as input parameters for the model simulations.

Gross, Silke; Gasteiger, Josef; Sauer, Daniel; Weinzierl, Bernadett

2013-04-01

59

Aerosol lidar intercomparison in the framework of the EARLINET project. 1. Instruments.  

PubMed

In the framework of the European Aerosol Research Lidar Network to Establish an Aerosol Climatology (EARLINET), 19 aerosol lidar systems from 11 European countries were compared. Aerosol extinction or backscatter coefficient profiles were measured by at least two systems for each comparison. Aerosol extinction coefficients were derived from Raman lidar measurements in the UV (351 or 355 nm), and aerosol backscatter profiles were calculated from pure elastic backscatter measurements at 351 or 355, 532, or 1064 nm. The results were compared for height ranges with high and low aerosol content. Some systems were additionally compared with sunphotometers and starphotometers. Predefined maximum deviations were used for quality control of the results. Lidar systems with results outside those limits could not meet the quality assurance criterion. The algorithms for deriving aerosol backscatter profiles from elastic lidar measurements were tested separately, and the results are described in Part 2 of this series of papers [Appl. Opt. 43, 977-989 (2004)]. In the end, all systems were quality assured, although some had to be modified to improve their performance. Typical deviations between aerosol backscatter profiles were 10% in the planetary boundary layer and 0.1 x 10(-6) m(-1) sr(-1) in the free troposphere. PMID:14960093

Matthais, Volker; Freudenthaler, Volker; Amodeo, Aldo; Balin, Ioan; Balis, Dimitris; Bösenberg, Jens; Chaikovsky, Anatoly; Chourdakis, Georgius; Comeron, Adolfo; Delaval, Arnaud; De Tomasi, Ferdinando; Eixmann, Ronald; Hågård, Arne; Komguem, Leonce; Kreipl, Stephan; Matthey, Renaud; Rizi, Vincenzo; Rodrigues, José António; Wandinger, Ulla; Wang, Xuan

2004-02-01

60

Spectrally resolved Raman lidar measurements of gaseous and liquid water in the atmosphere.  

PubMed

A spectrally resolved Raman lidar based on a tripled Nd:YAG laser is built for measuring gaseous and liquid water in the atmosphere. A double-grating polychromator with a reciprocal linear dispersion of ~0.237 nm mm(-1) is designed to achieve the wavelength separation and the suppression of elastic backscatter. A 32-channel linear-array photomultiplier tube is employed to sample atmospheric Raman water spectrum between 401.65 and 408.99 nm. The lidar-observed Raman water spectrum in the very clear atmosphere is nearly invariable in shape. It is dominated by water vapor, and can serve as background reference for Raman lidar identification of the phase state of atmospheric water under various weather conditions. The lidar has measured also the Raman water spectrum of an aerosol/liquid water layer. The spectrum showed a moderate increase of the signal on both sides of the Q-branch of water vapor. Noting that under clear weather conditions the Raman water spectrum intensity stays at a very low level in the 401.6-404.7 nm range, the Raman water signal in this portion can be used to estimate the liquid water content in the layer. PMID:24085202

Liu, Fuchao; Yi, Fan

2013-10-01

61

Lidar Aerosol Profiles Measured From Halifax During Summer 2007  

NASA Astrophysics Data System (ADS)

Measurements of aerosol profiles in the troposphere and lower stratosphere were obtained with a high-power Raman Lidar from Halifax, Nova Scotia (44.63N, 63.58W) on the East Coast of Canada during Summer 2007. Observations throughout the troposphere at high temporal resolution were made possible by using a new dual-receiver setup. The lidar was operated in clear-sky conditions, and several long duration (> 80 hours) data sets were obtained. The measurements reveal the presence of boundary-layer aerosols during episodes of pollution transport from the Eastern US and Canada, and are compared with surface measurements of ozone and other species. Boundary layer development, entrainment and mixing are evident in the data. Structured plumes at higher altitudes are traced back to biomass burning events throughout North America. Aerosols were also observed on two occasions at 15 km in altitude, and are most likely due to pyroconvection. The measurements are being used to help understand transport and mixing processes, and to form a climatology of aerosol export from North America during the summer months.

Crawford, L.; Duck, T. J.; Doyle, J.; Harris, R.; Beauchamp, S.

2007-12-01

62

A permanent Raman lidar station in the Amazon: description, characterization, and first results  

NASA Astrophysics Data System (ADS)

A permanent UV Raman lidar station, designed to perform continuous measurements of aerosols and water vapor and aiming to study and monitor the atmosphere from weather to climatic time scales, became operational in the central Amazon in July 2011. The automated data acquisition and internet monitoring enabled extended hours of daily measurements when compared to a manually operated instrument. This paper gives a technical description of the system, presents its experimental characterization and the algorithms used for obtaining the aerosol optical properties and identifying the cloud layers. Data from one week of measurements during the dry season of 2011 were analyzed as a mean to assess the overall system capability and performance. Both Klett and Raman inversions were successfully applied. A comparison of the aerosol optical depth from the lidar and from a co-located Aerosol Robotic Network (AERONET) sun photometer showed a correlation coefficient of 0.86. By combining nighttime measurements of the aerosol lidar ratio (50-65 sr), back-trajectory calculations and fire spots observed from satellites, we showed that observed particles originated from biomass burning. Cirrus clouds were observed in 60% of our measurements. Most of the time they were distributed into three layers between 11.5 and 13.4 km a.g.l. The systematic and long-term measurements being made by this new scientific facility have the potential to significantly improve our understanding of the climatic implications of the anthropogenic changes in aerosol concentrations over the pristine Amazonia.

Barbosa, H. M. J.; Barja, B.; Pauliquevis, T.; Gouveia, D. A.; Artaxo, P.; Cirino, G. G.; Santos, R. M. N.; Oliveira, A. B.

2014-06-01

63

Chamber LIDAR measurements of aerosolized biological simulants  

NASA Astrophysics Data System (ADS)

A chamber aerosol LIDAR is being developed to perform well-controlled tests of optical scattering characteristics of biological aerosols, including Bacillus atrophaeus (BG) and Bacillus thuringiensis (BT), for validation of optical scattering models. The 1.064 ?m, sub-nanosecond pulse LIDAR allows sub-meter measurement resolution of particle depolarization ratio or backscattering cross-section at a 1 kHz repetition rate. Automated data acquisition provides the capability for real-time analysis or recording. Tests administered within the refereed 1 cubic meter chamber can provide high quality near-field backscatter measurements devoid of interference from entrance and exit window reflections. Initial chamber measurements of BG depolarization ratio are presented.

Brown, David M.; Thrush, Evan P.; Thomas, Michael E.; Siegrist, Karen M.; Baldwin, Kevin; Quizon, Jason; Carter, Christopher C.

2009-05-01

64

Lidar detection of biological aerosols  

SciTech Connect

This paper reports the results of a systems analysis of the performance of a helicopter-based backscatter lidar system for long-range stand-off detection of clouds of biological warfare (BW) agents. With models the authors developed, they calculated the dispersion, transport, and detectability of a BW agent line-source (crop-duster-like) cloud as a function of elapsed time in an employment scenario. For a given BW attack, the authors calculated the time of first detection, determined the warning time, and from that, estimated the number of troops saved from exposure.

Wehner, T.R.; Stroud, P.D.; May, W.L. [Los Alamos National Lab., NM (United States)

1996-12-31

65

A water vapor Raman lidar as part of the Swiss meteorology service  

NASA Astrophysics Data System (ADS)

Vertical water vapor profiles with high time resolution are necessary for improved numerical weather prediction (NWP). Meteorological services rely, in part, on NWP models for short to mid-term weather forecasting. Typically vertical water vapor profiles are acquired from twice a day radiosonde observations which have time resolution insufficient to resolve rapidly changing meteorological phenomena. New operational instruments with near real-time sampling of the water vapor field are needed. Raman LIDARs can provide vertical humidity profiles within the troposphere with time and range resolution suitable for NWP model assimilation and validation. That is why in 2004 the Swiss meteo-service (MeteoSwiss), the Swiss Federal Institute of Technology in Lausanne (EPFL), and the Swiss National Science Foundation (SNSF), initiated a project to build an automated Raman lidar for day and night vertical profiling of tropospheric water vapor and aerosol properties. Currently RALMO (Raman Lidar for meteorological observations) is operational at MeteoSwiss aerological station at Payerne. It is fully automated, self-contained, eye-safe instrument for day and night-time vertical profiling of water vapor mixing ratio, aerosol backscatter, and extinction within the troposphere. The lidar profiles of water vapor mixing ratio have vertical resolution from 15 m (boundary layer) to 100-450 m (free troposphere) and time resolution of 2 min (boundary layer) to 30 min (free troposphere). The range resolved aerosol extinction and backscatter coefficients are measured with similar resolution. The lidar operational range is from ~50 m to 5 km during daytime (detection limit of 0.2 g/kg), and from ~50 m to 10 km night-time. LabView based software allows continuous fully automated operation. Automated data treatment software reads the accumulated lidar data, derives vertical profiles of water vapor mixing ratio (grams per kilogram of dry air) estimates statistical error, and stores the result for upload to MeteoSwiss. The operational time resolution is 30 min whereas the vertical resolution is 30 m; it is decreased if needed by steps of 30 m to keep the relative mixing ratio error below 10 %. Aerosol backscatter and extinction retrieval algorithms are available as well. In order to study the range independence and long term stability of the lidar calibration constant we carried out several intercomparisons of operationally retrieved lidar profiles with collocated radiosondes. We used Vaisala RS 92 and Snow-White chilled mirror hygrometer radiosondes attached to single balloon. In all cases there is excellent agreement of the lidar derived mixing ratio profiles with the radiosondes.

Dinoev, T.; Arshinov, Y.; Bobrovnikov, S.; Ristori, P.; Calpini, B.; van den Bergh, H.; Parlange, M. B.; Simeonov, V.

2009-09-01

66

Fluorescence from atmospheric aerosol detected by a lidar indicates biogenic particles in the lowermost stratosphere  

NASA Astrophysics Data System (ADS)

With a lidar system that was installed in Lindenberg/Germany, we observed in June 2003 an extended aerosol layer at 13km altitude in the lowermost stratosphere. This layer created an inelastic backscatter signal that we detected with a water vapour Raman channel, but that was not produced by Raman scattering. Also, we find evidence for inelastic scattering from a smoke plume from a forest fire that we observed in the troposphere. We interpret the unexpected properties of these aerosols as fluorescence induced by the laser beam at organic components of the aerosol particles. Fluorescence from ambient aerosol had not yet been considered detectable by lidar systems. However, organic compounds such as polycyclic aromatic hydrocarbons sticking to the aerosol particles, or bioaerosol such as bacteria, spores or pollen fluoresce when excited with UV-radiation in a way that is detectable by our lidar system. Therefore, we conclude that fluorescence from organic material released by biomass burning creates, inelastic backscatter signals that we measured with our instrument and thus demonstrate a new and powerful way to characterize aerosols by a remote sensing technique. The stratospheric aerosol layer that we have observed in Lindenberg for three consecutive days is likely to be a remnant from Siberian forest fire plumes lifted across the tropopause and transported around the globe.

Immler, F.; Engelbart, D.; Schrems, O.

2005-02-01

67

Characterization of the planetary boundary layer height and structure by Raman lidar: comparison of different approaches  

NASA Astrophysics Data System (ADS)

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

Summa, D.; Di Girolamo, P.; Stelitano, D.; Cacciani, M.

2013-12-01

68

Characterization of the planetary boundary layer height and structure by Raman lidar: comparison of different approaches  

NASA Astrophysics Data System (ADS)

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

Summa, D.; Di Girolamo, P.; Stelitano, D.; Cacciani, M.

2013-06-01

69

Argentinian multi-wavelength scanning Raman lidar to observe night sky atmospheric transmission  

E-print Network

This paper discusses the multi-wavelength scanning Raman lidar being built at Lidar Division, CEILAP (CITEDEF-CONICET) in the frame of the Argentinean Cherenkov Telescope Array (CTA) collaboration to measure the spectral characteristics of the atmospheric aerosol extinction profiles to provide better transmission calculations at the future CTA site. This lidar emits short laser pulses of 7-9 ns at 355, 532 and 1064 nm at 50 Hz with nominal energy of 125 mJ at 1064 nm. This wavelengths are also used to retrieve the atmospheric (air, aerosol and clouds) backscattered radiation in the UV, VIS and IR ranges. Raman capabilities were added in the UV and VIS wavelengths to retrieve the spectral characteristics of the aerosol extinction and the water vapor profile. Due to the expected low aerosol optical depth of the future site, the short observation period as well as the extension of the observation, an enhanced collection area is required. This system uses six 40 cm f/2.5 newtonian telescopes to avoid dealing with...

Pallotta, Juan; Otero, Lidia; Chouza, Fernando; Raul, Delia; Gonzalez, Francisco; Etchegoyen, Alberto; Quel, Eduardo

2013-01-01

70

Scanning Mobile Lidar for Aerosol Tracking and Biological Aerosol Identification  

NASA Astrophysics Data System (ADS)

Optical properties of non-biological aerosols containing aromatic hydrocarbons, such as industrial chemicals and engine exhausts, have already been thoroughly studied using remote sensing techniques. However, because of their complex composition and characteristics, the identification of biological aerosols, such as fungi, pollen and bacteria that are present in the environment remains a rather difficult task. The collection of information on both non-biological and biological aerosols is of great importance for understanding their interrelation, physical and chemical properties and their influence on human health and the environment. Biological and non-biological aerosols can be simultaneously detected, tracked and identified by a scanning mobile Mie-fluorescence lidar. The device developed at the University of Nova Gorica can perform azimuth and zenith angle scans with an angular resolution of 0.1°, as well as operate in both day and night-time conditions. Aerosols of biological origin are identified through the detection of the fluorescence of the amino acid tryptophan which is present in almost all substances of biological origin. In our system, the transmitter is a solid state Nd:YAG laser which is capable of simultaneous emission of light at a base wavelength of 1064 nm (IR) and its quadrupled wavelength of 266 nm (UV) at a maximum repetition rate of 10 Hz. Tryptophan contained in biological aerosols is excited by the 266 nm laser pulses and the returning fluorescence signals are detected in the spectral band centered at 295 nm. The receiver is a Newtonian telescope which uses a 300 mm parabolic mirror to direct received light into three detection channels - two elastic backscatter channels (IR and UV) and a fluorescence channel. First experiments show that the detection range of the lidar reaches 10 km in the IR channel and 3 km in the UV channel. Based on the preliminary simulations of the signal-to-noise ratio, the detection range for biological fluorescence signals at 295 nm is estimated to be 2 km. The measurements of the time-series indicate that the mobile lidar is capable of detecting and profiling clouds and aerosols in its detection range. Our future plans include establishing an automated, unattended environmental monitoring system that will allow full time continuous measurements in the desired solid angle around the lidar station.

He, Tingyao; Bergant, Klemen; Filip?i?, Andrej; Forte, Biagio; Gao, Fei; Stani?, Samo; Veberi?, Darko; Zavrtanik, Marko

2010-05-01

71

Lidar methods for measuring distributions and characteristics of aerosols and clouds  

Microsoft Academic Search

Mie scattering lidar methods for measuring aerosols and clouds are described. The concepts of Mie scattering lidars, depolarization measurements, and bistatic lidar methods will be described. High-spectral-resolution lidar (HSRL) method for measuring optical characteristics of aerosols and clouds will be also described. Lidar systems and recent applications of Mie scattering lidars will be then introduced. These include development of a

Nobuo Sugimoto

2003-01-01

72

Evaluation of Combined Active-Passive Aerosol Extinction Profile Retrieval Using Airborne High Spectral Resolution Lidar  

Microsoft Academic Search

Lidar remote sensing is a valuable means of measuring the vertical distribution of aerosol properties. To obtain a profile of aerosol extinction from a backscatter lidar requires an additional source of information, typically an assumed value of the aerosol extinction-to-backscatter ratio, or lidar ratio. We present results of a combined active plus passive retrieval of aerosol extinction from attenuated lidar

S. P. Burton; R. A. Ferrare; C. Kittaka; C. A. Hostetler; J. W. Hair; M. D. Obland; R. R. Rogers; A. L. Cook; D. B. Harper; L. A. Remer

2008-01-01

73

Automated detection of particulate layers and retrieval of their extinction from the ARM Raman lidar  

NASA Astrophysics Data System (ADS)

The DOE ARM program operates two Raman lidars (RLs), one near Lamont, Oklahoma and one in Darwin, Australia. These systems are far more advance than the ARM program's primary lidar the MPL (micropulse lidar) with the ability to directly measure extinction and a shorter wavelength laser--- which reduces the impact of solar background noise in the elastic channel. In this work, we make improvements to existing RL data products to take advantage of the full capabilities of the Raman lidar. We identify the presence of particulate (cloud and aerosol) layers using a context-sensitive threshold method applied to three quantities: (1) a scattering ratio calculated using a modeled clear-sky signal, (2) a scattering ratio calculated using the nitrogen channel, and (3) the depolarization ratio. Extinction in these layers are directly retrieved using the RL's nitrogen channel. However the nitrogen signal-to-noise ratio is much lower than the elastic channel. Therefore a careful examination of signal noise is made to determine when it is appropriate to use the nitrogen channel. In cases when the full profile of extinction cannot be directly measured, we use the elastic channel only to retrieve extinction by either using the transmission method or by assuming lidar ratio. From these three methods of extinction retrieval a best estimate of extinction is made along with uncertainty estimates derived from the analysis of signal noise.

Thorsen, T. J.; Fu, Q.; Turner, D. D.; Newsom, R. K.; Comstock, J. M.; Sivaraman, C.

2013-12-01

74

Aerosol Classification using Airborne High Spectral Resolution Lidar Measurements  

NASA Astrophysics Data System (ADS)

The NASA Langley Research Center (LaRC) airborne High Spectral Resolution Lidar (HSRL) on the NASA B200 aircraft has acquired extensive datasets of aerosol extinction (532 nm), aerosol optical thickness (AOT) (532 nm), backscatter (532 and 1064 nm), and depolarization (532 and 1064 nm) profiles during 18 field missions that have been conducted over North America since 2006. The lidar measurements of aerosol intensive parameters (lidar ratio, depolarization, backscatter color ratio, spectral depolarization ratio) are shown to vary with location and aerosol type. A methodology based on observations of known aerosol types is used to qualitatively classify the extensive set of HSRL aerosol measurements into eight separate types. Several examples are presented showing how the aerosol intensive parameters vary with aerosol type and how these aerosols are classified according to this new methodology. The HSRL-based classification reveals vertical variability of aerosol types during the NASA ARCTAS field experiment conducted over Alaska and northwest Canada during 2008. In two examples derived from flights conducted during ARCTAS, the HSRL classification of biomass burning smoke is shown to be consistent with aerosol types derived from coincident airborne in situ measurements of particle size and composition. The HSRL retrievals of aerosol optical thickness and inferences of aerosol types are used to apportion aerosol optical thickness to aerosol type; results of this analysis are shown for several experiments.

Burton, S. P.; Ferrare, R. A.; Hostetler, C. A.; Hair, J. W.; Obland, M. D.; Rogers, R.; Butler, C. F.; Cook, A.; Harper, D.; Froyd, K. D.

2011-12-01

75

A New Raman DIAL Technique for Measuring Stratospheric Ozone in the Presence of Volcanic Aerosols  

NASA Technical Reports Server (NTRS)

This paper describes a new lidar scheme to measure stratospheric ozone in the presence of heavy volcanic aerosol loading. The eruptions of the Philippine volcano Pinatubo during June 1991 ejected large amounts of sulfur dioxide into the atmosphere to altitudes of at least 30 km. The resulting aerosols have severely affected the measurements of stratospheric ozone when using traditional Rayleigh differential absorption lidar (DIAL) technique, in which the scattering mechanism is almost entirely Rayleigh and which assumes a small amount or no aerosols. In order to extract an ozone profile in the regions below about 30 km where the Rayleigh lidar returns are contaminated by aerosol scattering from Mt. Pinatubo cloud, we have used a Raman lidar technique, where the scattering mechanism depends solely on molecular nitrogen. In this scheme there is no aerosol scattering component to the backscattered lidar return. Using this technique in conjunction with the Rayleigh DIAL measurement, the GSFC stratospheric ozone lidar has measured ozone profiles between 15 and 50 km during the recently held UARS correlative measurement campaign (February-March 1992) at JPL's Table Mountain Facility in California.

Singh, Upendra N.; Mcgee, Thomas J.; Gross, Michael; Heaps, William S.; Ferrare, Richard

1992-01-01

76

Aerosol classification by airborne high spectral resolution lidar observations  

NASA Astrophysics Data System (ADS)

During four aircraft field experiments with the DLR research aircraft Falcon in 1998 (LACE), 2006 (SAMUM-1) and 2008 (SAMUM-2 and EUCAARI), airborne High Spectral Resolution Lidar (HSRL) and in situ measurements of aerosol microphysical and optical properties were performed. Altogether, the properties of six different aerosol types and aerosol mixtures - Saharan mineral dust, Saharan dust mixtures, Canadian biomass burning aerosol, African biomass burning aerosol, anthropogenic pollution aerosol, and marine aerosol have been studied. On the basis of this extensive HSRL data set, we present an aerosol classification scheme which is also capable to identify mixtures of different aerosol types. We calculated mixing lines that allowed us to determine the contributing aerosol types. The aerosol classification scheme was validated with in-situ measurements and backward trajectory analyses. Our results demonstrate that the developed aerosol mask is capable to identify complex stratifications with different aerosol types throughout the atmosphere.

Groß, S.; Esselborn, M.; Weinzierl, B.; Wirth, M.; Fix, A.; Petzold, A.

2012-10-01

77

Lidar observations of high-altitude aerosol layers (cirrus clouds)  

NASA Astrophysics Data System (ADS)

Aerosols, clouds and aerosol-cloud interactions are recognized as the key factors influencing the climate. Clouds are the primary modulators of the Earth's radiative budget. This paper focuses on the detection of high-altitude aerosol layers in the troposphere over mid-latitude lidar station in Sofia, Bulgaria. They are situated in the height-region 6 km÷16 km, with thickness in the range 0.2 km÷5 km and have varying optical characteristics. On the basis of the general utilized classification of the Cirrus clouds, high values of the calculated atmospheric backscatter coefficient and Angströmexponent estimation results we conclude that the registered strongly scattered aerosol layers are Cirrus clouds. Lidar measurements are performed with an aerosol lidar, equipped with Nd:YAG laser at wavelengths 532 nm and 1064 nm. Mainly, lidar data are presented in terms of vertical atmospheric backscatter coefficient profiles. We also include 2Dcolormap in height-time coordinates build on the basis of so called range corrected signals. It shows in general changes of the aerosol stratification over the lidar station during the measurement period. We employed HYSPLIT backward trajectories and DREAM forecasts to analyze the lidar profile outlines and characterize the events during which Cirrus cloud samples were observed. So was remarked that most of the results were obtained during Saharan dust long-way transport over the city of Sofia. Reported experimental examples are extracted from regular lidar investigations of the atmosphere within the frame of European project EARLINET.

Deleva, Atanaska D.; Grigorov, Ivan V.

2013-03-01

78

Aerosol classification by airborne high spectral resolution lidar observations  

NASA Astrophysics Data System (ADS)

During four aircraft field experiments with the DLR research aircraft Falcon in 1998 (LACE), 2006 (SAMUM-1) and 2008 (SAMUM-2 and EUCAARI), airborne High Spectral Resolution Lidar (HSRL) and in situ measurements of aerosol microphysical and optical properties were performed. Altogether, the properties of six different aerosol types and aerosol mixtures - Saharan mineral dust, Saharan dust mixtures, Canadian biomass burning aerosol, African biomass burning mixture, anthropogenic pollution aerosol, and marine aerosol have been studied. On the basis of this extensive HSRL data set, we present an aerosol classification scheme which is also capable to identify mixtures of different aerosol types. We calculated mixing lines that allowed us to determine the contributing aerosol types. The aerosol classification scheme was supported by backward trajectory analysis and validated with in-situ measurements. Our results demonstrate that the developed aerosol mask is capable to identify complex stratifications with different aerosol types throughout the atmosphere.

Groß, S.; Esselborn, M.; Weinzierl, B.; Wirth, M.; Fix, A.; Petzold, A.

2013-03-01

79

Aerosol lidar intercomparison in the framework of the EARLINET project. 2. Aerosol backscatter algorithms.  

PubMed

An intercomparison of aerosol backscatter lidar algorithms was performed in 2001 within the framework of the European Aerosol Research Lidar Network to Establish an Aerosol Climatology (EARLINET). The objective of this research was to test the correctness of the algorithms and the influence of the lidar ratio used by the various lidar teams involved in the EARLINET for calculation of backscatter-coefficient profiles from the lidar signals. The exercise consisted of processing synthetic lidar signals of various degrees of difficulty. One of these profiles contained height-dependent lidar ratios to test the vertical influence of those profiles on the various retrieval algorithms. Furthermore, a realistic incomplete overlap of laser beam and receiver field of view was introduced to remind the teams to take great care in the nearest range to the lidar. The intercomparison was performed in three stages with increasing knowledge on the input parameters. First, only the lidar signals were distributed; this is the most realistic stage. Afterward the lidar ratio profiles and the reference values at calibration height were provided. The unknown height-dependent lidar ratio had the largest influence on the retrieval, whereas the unknown reference value was of minor importance. These results show the necessity of making additional independent measurements, which can provide us with a suitable approximation of the lidar ratio. The final stage proves in general, that the data evaluation schemes of the different groups of lidar systems work well. PMID:14960094

Böckmann, Christine; Wandinger, Ulla; Ansmann, Albert; Bösenberg, Jens; Amiridis, Vassilis; Boselli, Antonella; Delaval, Arnaud; De Tomasi, Ferdinando; Frioud, Max; Grigorov, Ivan Videnov; Hågård, Arne; Horvat, Matej; Iarlori, Marco; Komguem, Leonce; Kreipl, Stephan; Larchevêque, Gilles; Matthias, Volker; Papayannis, Alexandros; Pappalardo, Gelsomina; Rocadenbosch, Francesc; Rodrigues, Jose António; Schneider, Johannes; Shcherbakov, Valery; Wiegner, Matthias

2004-02-01

80

The application of lidar to stratospheric aerosol studies  

NASA Technical Reports Server (NTRS)

The global climatology and understanding of stratospheric aerosols evolving primarily from lidar and satellite measurements is presented. The importance of validation of these remotely sensed data with in situ measurements is also discussed. The advantage of lidar for providing high vertical and horizontal resolution and its independence from a remote source for measurement will become evident with examples of long term lidar data sets at fixed sites and the use of lidar on airborne platforms. Volcanic impacts of the last 20 years are described with emphasis on the last 8 years where satellite data are available. With satellite and high resolution lidar measurements, an understanding of the global circulation of volcanic material is attempted along with the temporal change of aerosol physical parameters and the stratospheric cleansing or decay times associated with these eruptions.

Mccormick, M. P.

1986-01-01

81

AIRBORNE HIGH SPECTRAL RESOLUTION LIDAR MEASUREMENTS OF ATMOSPHERIC AEROSOLS  

E-print Network

Research Center (LaRC) recently developed an airborne High Spectral Resolution Lidar (HSRL) to measure aerosol distributions and optical properties. The HSRL technique takes advantage of the spectral aerosol extinction and backscatter independently. The LaRC instrument employs the HSRL technique

82

Simultaneous analog and photon counting detection for Raman lidar  

SciTech Connect

The Atmospheric Radiation Measurement program Raman Lidar was upgraded in 2004 with a new data system that provides simultaneous measurements of both the photomultiplier analog output voltage and photon counts. This paper describes recent improvements to the algorithm used to merge these two signals into a single signal with improved dynamic range. The impact of modifications to the algorithm are evaluated by comparing profiles of water vapor mixing ratio from the lidar with sonde measurements. The modifications that were implemented resulted in a reduction of the mean bias in the daytime mixing ratio from a 4% dry bias to well within 1%.

Newsom, Rob K.; Turner, David D.; Mielke, Bernd; Clayton, Marian F.; Ferrare, Richard; Sivaraman, Chitra

2009-07-10

83

First results from the aerosol lidar and backscatter sonde intercomparison campaign STRAIT'1997 at table mountain facility during February-March 1997  

NASA Technical Reports Server (NTRS)

First results of an intercomparison measurement campaign between three aerosol lidar instruments and in-situ backscatter sondes performed at Table Mountain Facility (34.4 deg N, 117.7 deg E, 2280 m asl) in February-March 1997 are presented. During the campaign a total of 414 hours of lidar data were acquired by the Aerosol-Temperature-Lidar (ATL, Goddard Space Flight Center) the Mobile-aerosol-Raman-Lidar (MARL, Alfred Wegener Institute), and the TMF-Aerosol-Lidar (TAL, Jet Propulsion Laboratory), and four backscatter sondes were launched. From the data set altitude profiles of backscatter ratio and volume depolarization of stratospheric background aerosols at altitudes between 15 and 25 km and optically thin high-altitude cirrus clouds at altitudes below 13 km are derived. On the basis of a sulfuric acid aerosol model color ratio profiles obtained from two wavelength lidar data are compared to the corresponding profiles derived from the sonde observations. We find an excellent agreement between the in-situ and ATL lidar data with respect to backscatter and color ratio. Cirrus clouds were present on 16 of 26 nights during the campaign. Lidar observations with 17 minute temporal and 120-300 m spatial resolution indicate high spatial and temporal variability of the cirrus layers. Qualitative agreement is found between concurrent lidar measurements of backscatter ratio and volume depolarization.

Beyerle, G.; Gross, M. R.; Haner, D. A.; Kjome, N. T.; McDermid, I. S.; McGee, T. J.; Rosen, J. M.; Schaefer, H. - J.; Schrems, O.

1998-01-01

84

Lidar-radar synergy for characterizing properties of ultragiant volcanic aerosol  

NASA Astrophysics Data System (ADS)

The atmospheric aerosol has a relevant effect on our life influencing climate, aviation safety, air quality and natural hazards. The identification of aerosol layers through inspection of continuous measurements is strongly recommended for quantifying their contribution to natural hazards and air quality and to establish suitable alerting systems. In particular, the study of ultragiant aerosols may improve the knowledge of physical-chemical processes underlying the aerosol-cloud interactions and the effect of giant nuclei as a potential element to expedite the warm-rain process. Moreover, the identification and the characterization of ultragiant aerosols may strongly contribute to quantify their impact on human health and their role in airplane engine damages or in visibility problems, especially in case of extreme events as explosive volcanic eruptions. During spring 2010, volcanic aerosol layers coming from Eyjafjallajökull volcano were observed over most of the European countries, using lidar technique. From 19 April to 19 May 2010, they were also observed at CNR-IMAA Atmospheric Observatory (CIAO) with the multi-wavelength Raman lidar systems of the Potenza EARLINET station (40.60N, 15.72E, 760 m a.s.l), Southern Italy. During this period, ultragiant aerosol were also observed at CIAO using a co-located Ka-band MIRA-36 Doppler microwave radar operating at 8.45 mm (35.5 GHz). The Ka-band radar observed in four separate days (19 April, 7, 10, 13 May) signatures consistent with the observations of non-spherical ultragiant aerosol characterized by anomalous values of linear depolarization ratio higher than -4 dB, probably related to the occurrence of multiple effects as particle alignment and presence of an ice coating. 7-days backward trajectory analysis shows that the air masses corresponding to the ultragiant aerosol observed by the radar were coming from the Eyjafjallajökull volcano area. Only in one case the trajectories do not come directly from Iceland, but from Central Europe where many lidar observations confirm the presence of volcanic aerosol in the previous days. Therefore, both CIAO lidar observations and the backtrajectory analysis suggests a volcanic origin of the ultragiant aerosol observed by the radar, revealing that these particles might have travelled for more than 4000 km after their injection into the atmosphere. The reported observation fostered a study, reported in this work, about the performances of multi-wavelength Raman lidars in the identification and the characterization of ultragiant aerosols layers in the troposphere. Results from simulations using Mie, T-Matrix and ray-tracing codes will be presented and compared with the observations performed in April-May 2010 during the Eyjafjallajökull eruption. Sensitivity ranges in detection of aerosol layer are pointed out in terms of experimental limits of both lidar and radar techniques and of aerosol optical depth. Moreover, recommendations for use of a combined lidar-radar approach for the aerosol typing and for the retrieval of their microphysical properties are reported.

Madonna, F.; Amodeo, A.; D'Amico, G.; Giunta, A.; Mona, L.; Pappalardo, G.

2011-12-01

85

Airborne high spectral resolution lidar for measuring aerosol extinction and backscatter coefficients.  

PubMed

An airborne high spectral resolution lidar (HSRL) based on an iodine absorption filter and a high-power frequency-doubled Nd:YAG laser has been developed to measure backscatter and extinction coefficients of aerosols and clouds. The instrument was operated aboard the Falcon 20 research aircraft of the German Aerospace Center (DLR) during the Saharan Mineral Dust Experiment in May-June 2006 to measure optical properties of Saharan dust. A detailed description of the lidar system, the analysis of its data products, and measurements of backscatter and extinction coefficients of Saharan dust are presented. The system errors are discussed and airborne HSRL results are compared to ground-based Raman lidar and sunphotometer measurements. PMID:18204721

Esselborn, Michael; Wirth, Martin; Fix, Andreas; Tesche, Matthias; Ehret, Gerhard

2008-01-20

86

Case study of multiple-wavelength lidar backscatter from aerosols  

NASA Astrophysics Data System (ADS)

Range-resolved co-pointing multiple wavelength lidar backscatter from aerosols is analyzed for a summer day in the northeast United States. Lidar backscatter wavelengths are 355 nm, 532 nm, and 1064 nm and were measured at a vertical range gate of 60 meters. The altitude range of lidar measurement is from the surface to 4 km above ground level and the measurement period spanned five hours from late afternoon through several hours after sunset. Vertical profiles of temperature, relative humidity, and wind velocity, and surface visibility, were also measured to characterize the prevailing air mass. Lidar aerosol backscatter was significant through 3 km and diminished rapidly above. Several aerosol models selected on an a priori basis are used to compute backscatter ratios for wavelength pairs using scattering theory. These are compared with the profiles of measured backscatter ratios in an attempt to infer the type of aerosol present in the lower atmosphere and estimate multiple wavelength extinction. Measured backscatter ratios agreed with the ratios for soot, water-soluble, and haze aerosol models at the lowest altitudes with little agreement above 1 km for any model. Extinction estimates derived from lidar backscatter at 300 m were significantly higher than the corresponding values deduced from surface observations.

Roadcap, John R.; Dao, Phan D.; McNicholl, Patrick J.

2003-09-01

87

Vertical Structure of a Nonprecipitating Cold Frontal Head as Revealed by Raman Lidar and Wind Profiler Observations  

Microsoft Academic Search

The vertical distributions of water vapor, aerosols and cloud backscattering, and three-dimensional wind were measured using a Raman lidar and a wind profiler during the passage of a non-precipitating cold front during the night of 19-20 March 2002 over Tsukuba, Japan. The passage of the cold frontal head was identified by a sharp drop in the temperature at a height

Tetsu SAKAI; Tomohiro NAGAI; Takatsugu MATSUMURA; Masahisa NAKAZATO; Masahiro SASAOKA

2005-01-01

88

Post-volcanic stratospheric aerosol decay as measured by lidar  

NASA Technical Reports Server (NTRS)

The paper summarizes and discusses results of lidar observations, at Hampton (Virginia), of the stratospheric aerosol vertical distribution for a period of 22 months (October 1974 to July 1976) after the volcanic eruption of the Volcan de Fuego in Guatemala. Data are presented in terms of lidar scattering ratio, vertically integrated aerosol backscattering, layer structure and location, and rawinsonde temperature profiles as a function of time. The results reveal a sudden increase in the stratospheric aerosol content after the volcanic eruption as well as its subsequent decline. There exists a high degree of correlation between the integrated aerosol backscattering and the tropopause height such that as one decreases the other increases and vice versa. Rapid decay of the stratospheric aerosol is found to occur over the late winter to early spring period.

Mccormick, M. P.; Chu, W. P.; Fuller, W. H., Jr.; Swissler, T. J.

1978-01-01

89

Raman DIAL measurements of stratospheric ozone in the presence of volcanic aerosols  

NASA Technical Reports Server (NTRS)

Since the eruption of Mt. Pinatubo in June, 1991, measurements of atmospheric species which depend on Rayleigh scattering of radiation, have been severely compromised where the volcanic aerosol cloud exists. For the GSFC stratospheric ozone lidar, this has meant that ozone determination has been impossible below approximately 30 km. The GSFC lidar has been modified to detect Raman scattering from nitrogen molecules from transmitted laser wavelengths. The instrument transmits two laser wavelengths at 308 nm and 351 nm, and detects returns at four wavelengths; 308 nm, 332 nm, 351 nm, and 382 nm. Using this technique in conjunction with the Rayleigh DIAL measurement, ozone profiles have been measured between 15 and 50 km.

Mcgee, Thomas J.; Gross, Michael; Ferrare, Richard; Heaps, William; Singh, Upendra

1993-01-01

90

Multi-wavelength multi-angular lidar for aerosol characterization  

Microsoft Academic Search

A multi-wavelength, multi-static lidar has been designed and is being tested for the characterization of atmospheric aerosols. This design builds upon multi-static lidar, multiple scattering analyses, and supercontinuum DIAL experiments that have previously been developed at Penn State University. Scattering measurements at two polarizations are recorded over a range of angles using CCD imagers. Measurements are made using three discrete

Andrea M. Wyant; David M. Brown; Perry S. Edwards; C. Russell Philbrick

2009-01-01

91

Spaceborne profiling of atmospheric temperature and particle extinction with pure rotational Raman lidar and of relative humidity in combination with differential absorption lidar: performance simulations  

SciTech Connect

The performance of a spaceborne temperature lidar based on the pure rotational Raman (RR) technique in the UV has been simulated. Results show that such a system deployed onboard a low-Earth-orbit satellite would provide global-scale clear-sky temperature measurements in the troposphere and lower stratosphere with precisions that satisfy World Meteorological Organization (WMO) threshold observational requirements for numerical weather prediction and climate research applications. Furthermore, nighttime temperature measurements would still be within the WMO threshold observational requirements in the presence of several cloud structures. The performance of aerosol extinction measurements from space, which can be carried out simultaneously with temperature measurements by RR lidar, is also assessed. Furthermore, we discuss simulations of relative humidity measurements from space obtained from RR temperature measurements and water-vapor data measured with the differential absorption lidar (DIAL) technique.

Di Girolamo, Paolo; Behrendt, Andreas; Wulfmeyer, Volker

2006-04-10

92

UV-LIF lidar for standoff BW aerosol detection  

NASA Astrophysics Data System (ADS)

An ultraviolet (UV) laser induced fluorescence (LIF) light detection and ranging (LIDAR) system has been constructed and commissioned by Dstl and demonstrated to be an effective technique for discriminating between some common fluorescent potentially interfering aerosols and biological warfare agent (BWA) simulants at a distance remote from the release. The Mk 3 UV-LIF LIDAR employs the fundamental wavelength (1064 nm) of a Nd:YAG laser to spatially map aerosol clouds, and the fourth harmonic (266 nm) to excite fluorescence. The fluorescence emission is spectrally resolved into ten detection channels between 300-500 nm, permitting classification by a discrimination algorithm. The UV-LIF LIDAR was trialled in 2007 in the Joint Ambient Breeze Tunnel (JABT) and on the open range, at the US Army Dugway Proving Ground (DPG), Utah. In the JABT, calibration instruments were used to characterise the BWA simulant and interferent aerosol releases, permitting calculation of the system's limits of detection (LoD) and discrimination ability.

Hopkins, Rebecca J.; Barrington, Stephen J.; Castle, Michael J.; Baxter, Karen L.; Felton, Nicola V.; Jones, Joseph; Griffiths, Clare; Foot, Virginia; Risbey, Kit

2009-09-01

93

Using airborne high spectral resolution lidar data to evaluate combined active plus passive retrievals of aerosol extinction profiles  

Microsoft Academic Search

We derive aerosol extinction profiles from airborne and space-based lidar backscatter signals by constraining the retrieval with column aerosol optical thickness (AOT), with no need to rely on assumptions about aerosol type or lidar ratio. The backscatter data were acquired by the NASA Langley Research Center airborne High Spectral Resolution Lidar (HSRL) and by the Cloud-Aerosol Lidar with Orthogonal Polarization

S. P. Burton; R. A. Ferrare; C. A. Hostetler; J. W. Hair; C. Kittaka; M. A. Vaughan; M. D. Obland; R. R. Rogers; A. L. Cook; D. B. Harper; L. A. Remer

2010-01-01

94

Lidar data assimilation for improved analyses of volcanic aerosol events  

NASA Astrophysics Data System (ADS)

Observations of hazardous events with release of aerosols are hardly analyzable by today's data assimilation algorithms, without producing an attenuating bias. Skillful forecasts of unexpected aerosol events are essential for human health and to prevent an exposure of infirm persons and aircraft with possibly catastrophic outcome. Typical cases include mineral dust outbreaks, mostly from large desert regions, wild fires, and sea salt uplifts, while the focus aims for volcanic eruptions. In general, numerical chemistry and aerosol transport models cannot simulate such events without manual adjustments. The concept of data assimilation is able to correct the analysis, as long it is operationally implemented in the model system. Though, the tangent-linear approximation, which describes a substantial precondition for today's cutting edge data assimilation algorithms, is not valid during unexpected aerosol events. As part of the European COPERNICUS (earth observation) project MACC II and the national ESKP (Earth System Knowledge Platform) initiative, we developed a module that enables the assimilation of aerosol lidar observations, even during unforeseeable incidences of extreme emissions of particulate matter. Thereby, the influence of the background information has to be reduced adequately. Advanced lidar instruments comprise on the one hand the aspect of radiative transfer within the atmosphere and on the other hand they can deliver a detailed quantification of the detected aerosols. For the assimilation of maximal exploited lidar data, an appropriate lidar observation operator is constructed, compatible with the EURAD-IM (European Air Pollution and Dispersion - Inverse Model) system. The observation operator is able to map the modeled chemical and physical state on lidar attenuated backscatter, transmission, aerosol optical depth, as well as on the extinction and backscatter coefficients. Further, it has the ability to process the observed discrepancies with lidar data in a variational data assimilation algorithm. The implemented method is tested by the assimilation of CALIPSO attenuated backscatter data that were taken during the eruption of the Eyjafjallajökull volcano in April 2010. It turned out that the implemented module is fully capable to integrate unexpected aerosol events in an automatic way into reasonable analyses. The estimations of the aerosol mass concentrations showed promising properties for the application of observations that are taken by lidar systems with both, higher and lower sophistication than CALIOP.

Lange, Anne Caroline; Elbern, Hendrik

2014-05-01

95

Lidar determination of the composition of atmosphere aerosols  

NASA Technical Reports Server (NTRS)

Theoretical and experimental studies of the feasibility of using DIfferential SCatter (DISC) lidar to measure the composition of atmospheric aerosols are described. This technique involves multiwavelength measurements of the backscatter cross section of aerosols in the middle infrared, where a number of materials display strong restrahlen features that significantly modulate the backscatter spectrum. The theoretical work indicates that a number of materials of interest, including sulfuric acid, ammonium sulfate, and silicates, can be discriminated among with a CO2 lidar. An initial evaluation of this procedure was performed in which cirrus clouds and lower altitude tropospheric aerosols were developed. The observed ratio spectrum of the two types of aerosol displays structure that is in crude accord with theoretical expectations.

Wright, M. L.

1980-01-01

96

[The echelle grating monochromator's design of pure rotational Raman Lidar].  

PubMed

The pure rotization oal Raman Lidar temperature measurement system usually retrieve atmospheric temperature according to the echo signal of high and low-level quantum numbers of N2 moleules. An effective method to detect the rotational Raman spectrum is taking a grating monochromator. In the present paper the detection principle and the structure of the echelle grating monochromator are described, the high order and lower order quantum number of the probe spectrum is resolved. The focal length of the collimating-focusing optical system is calculated by analyzing echelle grating's spectroscopic principle and dispersion ability. Subsequently spectral effect is simulated with Zemax software. The simulation result indicates that under the condition of the probe laser wavelength of 532 nm and using echelle grating monochromator, Rarnan spectrums of 529.05, 530.40, 533.77, 535.13 mn can be separated well, at the same time, the SNR of the system is enhanced by summing the spectral signals of symmetric quantum number. The echelle grating monochromator is small in size, and can easily meet the requirements of the miniaturization of Raman Lidar temperature measurement system. PMID:23697156

Ge, Xian-Ying; Chen, Si-Ying; Zhang, Yin-Chao; Chen, He; Guo, Pan; Bu, Zhi-Chao; Chen, Sheng-Zhe

2013-02-01

97

High resolution scanning Raman lidar validation field campaign and internal boundary layer measurement  

Microsoft Academic Search

Measurements using a new generation high resolution scanning Raman lidar are presented. The lidar was applied at an intensive field campaign over a small lake in Fribourg region, Switzerland. The unique optimized design of this lidar, from laser to polychromators, allowed for the measurement of water vapor and temperature profiles and high resolution scans with good signal to noise ratio

M. Froidevaux; C. Higgins; V. Simeonov; P. Ristori; I. Serikov; H. van den Bergh; M. B. Parlange

2009-01-01

98

Middle atmosphere Doppler lidar and aerosol observations on scales down to seconds  

NASA Astrophysics Data System (ADS)

Noctilucent clouds (NLC) are the visible manifestation of ice particles in the polar summer mesopause region. These clouds are often modulated by gravity waves on scales of seconds and a few 100 m. Since 1997 NLC have been observed regularly by the ALOMAR Rayleigh/Mie/Raman (RMR) lidar in Northern Norway at 69N, 16E. Only recently the lidar was upgraded to allow higher temporal resolution. Now the modulation of the NLC layer can be observed with sub-second time resolution even during daytime. The lidar also uses a molecular absorption spectrometer to calculate Doppler winds in the strato- and mesosphere. In combination with simultaneous temperature and aerosol measurements the propagation of gravity waves can be investigated. We present high resolution lidar observations of waves in NLC. We observe that the spectrum of fluctuations follows those of saturated gravity waves down to the signal to noise limit of about 10 seconds. Using the capability of the lidar to perform observations at two different locations in the NLC layer we compare those to satellite observations by the cloud imaging and particle size (CIPS) instrument with a horizontal resolution of about 5 km. We observe that the horizontal and temporal structure agrees well only when taking coincident (<10min) and common volume (<10 km) observations. We present initial results on the propagation of waves in temperature and wind throughout the middle atmosphere.

Baumgarten, G.; Chandran, A.; Fiedler, J.; Hildebrand, J.; Hoffmann, P.; Kaifler, N.; Luebken, F.; Randall, C. E.; Lumpe, J. D.

2011-12-01

99

Long-term Aerosol Lidar Measurements At CNR-IMAA  

NASA Astrophysics Data System (ADS)

Actual estimations of the aerosol effect on the radiation budget are affected by a large uncertainties mainly due to the high inhomogeneity and variability of atmospheric aerosol, in terms of concentration, shape, size distribution, refractive index and vertical distribution. Long-term measurements of vertical profiles of aerosol optical properties are needed to reduce these uncertainties. At CNR-IMAA (40° 36'N, 15° 44' E, 760 m above sea level), a lidar system for aerosol study is operative since May 2000 in the framework of EARLINET (European Aerosol Research Lidar Network). Until August 2005, it provided independent measurements of aerosol extinction and backscatter at 355 nm and aerosol backscatter profiles at 532 nm. After an upgrade of the system, it provides independent measurements of aerosol extinction and backscatter profiles at 355 and 532 nm, and of aerosol backscatter profiles at 1064 nm and depolarization ratio at 532 nm. For these measurements, lidar ratio at 355 and 532 nm and Angstrom exponent profiles at 355/532 nm are also obtained. Starting on May 2000, systematic measurements are performed three times per week according to the EARLINET schedule and further measurements are performed in order to investigate particular events, like dust intrusions, volcanic eruptions and forest fires. A climatological study has been carried out in terms of the seasonal behavior of the PBL height and of the aerosol optical properties calculated inside the PBL itself. In the free troposphere, an high occurrences of Saharan dust intrusions (about 1 day of Saharan dust intrusion every 10 days) has been observed at CNR-IMAA because of the short distance from the Sahara region. During 6 years of observations, very peculiar cases of volcanic aerosol emitted by Etna volcano and aerosol released by large forest fires burning occurred in Alaska and Canada have been observed in the free troposphere at our site. Particular attention is devoted to lidar ratio both for the PBL and the free troposphere region, in order to study influences of aerosol modification/transportation processes on its values and its variability. ACKNOWLEDGMENTS The financial support of this work by the European Commission under grant RICA-025991 is gratefully acknowledged.

Mona, L.; Amodeo, A.; D'Amico, G.; Pandolfi, M.; Pappalardo, G.

2006-12-01

100

Airborne High Spectral Resolution Lidar Aerosol Measurements during ARCTAS  

Microsoft Academic Search

The NASA Langley Research Center (LaRC) airborne High Spectral Resolution Lidar (HSRL) on the NASA B200 aircraft measured aerosol extinction (532 nm), backscatter (532 and 1064 nm), and depolarization (532 and 1064 nm) profiles during the 2008 Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) field campaign. HSRL data were acquired during 15 science flights

R. A. Ferrare; C. A. Hostetler; J. W. Hair; A. Cook; D. Harper; S. P. Burton; M. D. Obland; R. Rogers; A. J. Swanson; A. D. Clarke; C. S. McNaughton; Y. Shinozuka; J. Redemann; J. M. Livingston; P. B. Russell; C. A. Brock; D. A. Lack; K. D. Froyd; J. A. Ogren; B. Andrews; A. Laskin; R. Moffet; M. K. Gilles; A. Nenes; T. L. Lathem; P. Liu

2009-01-01

101

The RAMNI airborne lidar for cloud and aerosol research  

NASA Astrophysics Data System (ADS)

We describe an airborne lidar for the characterization of atmospheric aerosol. The system has been set up in response to the need to monitor extended regions where the air traffic may be posed at risk by the presence of potentially harmful volcanic ash, and to study the characteristics of volcanic emissions both near the source region and when transported over large distances. The lidar provides backscatter and linear depolarization profiles at 532 nm, from which aerosol and cloud properties can be derived. The paper presents the characteristics and capabilities of the lidar system and gives examples of its airborne deployment. Observations from three flights, aimed at assessing the system capabilities in unperturbed atmospheric conditions, and at characterizing the emissions near a volcanic ash source (Mt. Etna) and transported far away from the source, are presented and discussed.

Cairo, F.; Di Donfrancesco, G.; Di Liberto, L.; Viterbini, M.

2012-07-01

102

Lidar profiling of aerosol optical and microphysical properties from space: overview, review, and outlook  

NASA Astrophysics Data System (ADS)

The potential of spaceborne lidar to monitor aerosol layering and mixing with high vertical resolution is reviewed. An overview is presented on aerosol lidar techniques of past, present, and future NASA and ESA lidar missions. The potential of a standard backscatter lidar (LITE, 1994), a backscatter/polarization lidar (CALIPSO, since 2006), a polarization High Spectral Resolution Lidar (HSRL, ATLID, EARTHCARE), and of a multiwavelength polarization HSRL are discussed regarding their ability to derive height profiles of optical and microphysical properties of aerosols and to resolve aerosol types and mixtures as a function of height. The important role of ground-truth activities is emphasized. Measurement examples taken with ground-based lidars illustrate that these systems provide a detailed characterization of complex aerosol scenarios in contrast to the snapshot-like observations with spaceborne lidars.

Ansmann, A.; Müller, D.; Wandinger, U.; Mamouri, R. E.

2013-08-01

103

Retrievals of profiles of fine and coarse aerosols using lidar and radiometric space measurements  

Microsoft Academic Search

The Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) spaceborne lidar, expected to be launched in 2004, will collect profiles of the lidar attenuated backscattering coefficients of aerosol and clouds at 0.53 and 1.06 ?m. The measurements are sensitive to the vertical distribution of aerosols. However, the information is insufficient to be mapped into unique aerosol physical properties and vertical

Yoram J. Kaufman; Didier Tanré; Jean-François Léon; Jacques Pelon

2003-01-01

104

Light-detection electronics for a Raman lidar  

NASA Technical Reports Server (NTRS)

A light-detection system for an optical radar, or lidar, unit to be used for remote temperature and composition measurements was designed, built, and bench tested. This detection system processes three return signal wavelengths: two Raman wavelengths, and the Rayleigh-Mie wavelength at 694.3 nanometers. Means of coping with photomultiplier tube instabilities and limitations are discussed. Circuits for gain control, ranging, and digitizing are included. The phototube gains can be switched fully on in 80 meters (450 nsec) or off in 30 meters (200 nsec) of range. The range circuit processes signals from 0.1 to 2 kilometers, with an estimated range resolution of less than 5 meters.

Leser, R. J.; Salzman, J. A.

1972-01-01

105

Lidar for remote sensing; Proceedings of the Meeting, Berlin, Germany, June 24-26, 1992  

SciTech Connect

The present volume on lidar for remote sensing discusses lidar system techniques for remote sensing of atmospheric pollution, airborne and surface-based lidar for environmental sensing of water and oceans, Doppler lidar for wind sensing and related measurement, aerosol measurements using lidar, ozone, water vapor, temperature, and density sensing with lidar systems, and new lidar technology systems and concepts. Attention is given to remote sensing of air pollution over large European cities by lidar, differential absorption lidar monitoring of atmospheric atomic mercury, an experimental evaluation of an airborne depth-sounding lidar, and remote sensing of the sea by tunable multichannel lidar. Topics addressed include recent developments in lidar techniques to measure the wind in the middle atmosphere, recent stratospheric aerosol measurements with a combined Raman elastic-backscatter lidar, the development of an eye-safe IR aerosol lidar, and temperature measurement by rotational Raman lidar.

Becherer, R.J.; Werner, C.

1992-01-01

106

Comparison of Aerosol Classification From Airborne High Spectral Resolution Lidar and the CALIPSO Vertical Feature Mask  

NASA Technical Reports Server (NTRS)

Knowledge of aerosol composition and vertical distribution is crucial for assessing the impact of aerosols on climate. In addition, aerosol classification is a key input to CALIOP aerosol retrievals, since CALIOP requires an inference of the lidar ratio in order to estimate the effects of aerosol extinction and backscattering. In contrast, the NASA airborne HSRL-1 directly measures both aerosol extinction and backscatter, and therefore the lidar ratio (extinction-to-backscatter ratio). Four aerosol intensive properties from HSRL-1 are combined to infer aerosol type. Aerosol classification results from HSRL-1 are used here to validate the CALIOP aerosol type inferences.

Burton, Sharon P.; Ferrare, Rich A.; Omar, Ali H.; Vaughan, Mark A.; Rogers, Raymond R.; Hostetler, Chris a.; Hair, Johnathan W.; Obland, Michael D.; Butler, Carolyn F.; Cook, Anthony L.; Harper, David B.

2012-01-01

107

Comparison between lidar and nephelometer measurements of aerosol hygroscopicity at the  

E-print Network

Comparison between lidar and nephelometer measurements of aerosol hygroscopicity at the Southern a significant effect on radiative properties of aerosols. Here a lidar method, applicable to cloud-capped, well a lidar-derived growth factor (measured over the range 85% RH to 96% RH) with a nephelometer- derived

108

Atmospheric aerosol profiling with a bistatic imaging lidar system.  

PubMed

Atmospheric aerosols have been profiled using a simple, imaging, bistatic lidar system. A vertical laser beam is imaged onto a charge-coupled-device camera from the ground to the zenith with a wide-angle lens (CLidar). The altitudes are derived geometrically from the position of the camera and laser with submeter resolution near the ground. The system requires no overlap correction needed in monostatic lidar systems and needs a much smaller dynamic range. Nighttime measurements of both molecular and aerosol scattering were made at Mauna Loa Observatory. The CLidar aerosol total scatter compares very well with a nephelometer measuring at 10 m above the ground. The results build on earlier work that compared purely molecular scattered light to theory, and detail instrument improvements. PMID:17514239

Barnes, John E; Sharma, N C Parikh; Kaplan, Trevor B

2007-05-20

109

Lidar determination of winds by aerosol inhomogeneities - Motion velocity in the planetary boundary layer  

Microsoft Academic Search

The paper presents results from lidar measurements of wind velocity in the planetary boundary layer using correlation data processing. Two lidars are used in the experiments: a ruby lidar operating along slant paths and a YAG:Nd lidar operating for near vertical sounding. On the basis of prior experience the optimal sizes of aerosol inhomogeneities (30-300 m), the duration of the

Ivan Kolev; Orlin Parvanov; Boiko Kaprielov

1988-01-01

110

The double grating monochromator's design for pure rotational Raman lidar  

NASA Astrophysics Data System (ADS)

The pure rotational Raman lidar temperature measurement system is usually used for retrieval of atmospheric temperature according to the echo signal ratio of high and low-level quantum numbers of N2 molecules which are consistent with the exponential relationship. An effective method to detect the rotational Raman spectrum is taking a double grating monochromator. In this paper the detection principle and the structure of the dual-grating monochromator are described, with analysis of rotational Raman's Stokes and anti-Stokes spectrums of N2 molecule, the high order and lower order quantum number of the probe spectrum are resolved, then the specific design parameters are presented. Subsequently spectral effect is simulated with Zemax software. The simulation result indicates that under the condition of the probe laser wavelength of 532nm and using double-grating spectrometer which is comprised by two blazed gratings, Raman spectrums of 529.05nm, 530.40nm, 533.77nm, 535.13nm can be separated well, and double-grating monochromator has high diffraction efficiency.

Ge, Xian-ying; Chen, He; Zhang, Yin-chao; Chen, Si-ying; Guo, Pan; Mu, Tao-tao; Bu, Zhi-chao; Yang, Jian

2013-09-01

111

Aerosol profiling with lidar in the Amazon Basin during the wet and dry season  

NASA Astrophysics Data System (ADS)

For the first time, multiwavelength polarization Raman lidar observations of optical and microphysical particle properties over the Amazon Basin are presented. The fully automated advanced Raman lidar was deployed 60 km north of Manaus, Brazil (2.5°S, 60°W) in the Amazon rain forest from January to November 2008. The measurements thus cover both the wet season (Dec-June) and the dry or burning season (July-Nov). Two cases studies of young and aged smoke plumes are discussed in terms of spectrally resolved optical properties (355, 532, and 1064 nm) and further lidar products such as particle effective radius and single-scattering albedo. These measurement examples confirm that biomass burning aerosols show a broad spectrum of optical, microphysical, and chemical properties. The statistical analysis of the entire measurement period revealed strong differences between the pristine wet and the polluted dry season. African smoke and dust advection frequently interrupt the pristine phases during the wet season. Compared to pristine wet season conditions, the particle scattering coefficients in the lowermost 2 km of the atmosphere were found to be enhanced, on average, by a factor of 4 during periods of African aerosol intrusion and by a factor of 6 during the dry (burning) season. Under pristine conditions, the particle extinction coefficients and optical depth for 532 nm wavelength were frequently as low as 10-30 Mm-1 and <0.05, respectively. During the dry season, biomass burning smoke plumes reached to 3-5 km height and caused a mean optical depth at 532 nm of 0.26. On average during that season, particle extinction coefficients (532 nm) were of the order of 100 Mm-1 in the main pollution layer (up to 2 km height). Ångström exponents were mainly between 1.0 and 1.5, and the majority of the observed lidar ratios were between 50-80 sr.

Baars, H.; Ansmann, A.; Althausen, D.; Engelmann, R.; Heese, B.; Müller, D.; Artaxo, P.; Paixao, M.; Pauliquevis, T.; Souza, R.

2012-11-01

112

Stable Calibration of Raman Lidar Water-Vapor Measurements  

NASA Technical Reports Server (NTRS)

A method has been devised to ensure stable, long-term calibration of Raman lidar measurements that are used to determine the altitude-dependent mixing ratio of water vapor in the upper troposphere and lower stratosphere. Because the lidar measurements yield a quantity proportional to the mixing ratio, rather than the mixing ratio itself, calibration is necessary to obtain the factor of proportionality. The present method involves the use of calibration data from two sources: (1) absolute calibration data from in situ radiosonde measurements made during occasional campaigns and (2) partial calibration data obtained by use, on a regular schedule, of a lamp that emits in a known spectrum determined in laboratory calibration measurements. In this method, data from the first radiosonde campaign are used to calculate a campaign-averaged absolute lidar calibration factor (t(sub 1)) and the corresponding campaign-averaged ration (L(sub 1)) between lamp irradiances at the water-vapor and nitrogen wavelengths. Depending on the scenario considered, this ratio can be assumed to be either constant over a long time (L=L(sub 1)) or drifting slowly with time. The absolutely calibrated water-vapor mixing ratio (q) obtained from the ith routine off-campaign lidar measurement is given by q(sub 1)=P(sub 1)/t(sub 1)=LP(sub 1)/P(sup prime)(sub 1) where P(sub 1) is water-vapor/nitrogen measurement signal ration, t(sub 1) is the unknown and unneeded overall efficiency ratio of the lidar receiver during the ith routine off-campaign measurement run, and P(sup prime)(sub 1) is the water-vapor/nitrogen signal ratio obtained during the lamp run associated with the ith routine off-campaign measurement run. If L is assumed constant, then the lidar calibration is routinely obtained without the need for new radiosonde data. In this case, one uses L=L(sub 1) = P(sup prime)(sub 1)/t(sub 1), where P(sub 1)(sup prime) is the water-vapor/nitrogen signal ratio obtained during the lamp run associated with the first radiosonde campaign. If L is assumed to drift slowly, then it is necessary to postpone calculation of a(sub 1) until after a second radiosonde campaign. In this case, one obtains a new value, L(sub 2), from the second radiosonde campaign, and for the ith routine off-campaign measurement run, one uses an intermediate value of L obtained by simple linear time interpolation between L(sub 1) and L(sub 2).

Leblanc, Thierry; McDermid, Iain S.

2008-01-01

113

Tropospheric ozone differential-absorption lidar using stimulated Raman scattering in carbon dioxide  

NASA Astrophysics Data System (ADS)

A UV ozone differential-absorption lidar (DIAL) utilizing a Nd:YAG laser and a single Raman cell filled with carbon dioxide (CO2) is designed, developed, and evaluated. The generated wavelengths are 276, 287, and 299 nm, comprising the first to third Stokes lines of the stimulated Raman scattering technique. The correction terms originated from the aerosol extinction, the backscatter, and the absorption by other gases are estimated using a model atmosphere. The experimental results demonstrate that the emitted output energies were 13 mJ/pulse at 276 nm and 287 nm and 5 mJ/pulse at 299 nm, with pump energy of 91 mJ/pulse and a CO2 pressure of 0.7 MPa. The three Stokes lines account for 44.0% of the available energy. The use of argon or helium as a buffer gas in the Raman cell was also investigated, but this leads to a dramatic decrease in the third Stokes line, which makes this wavelength practically unusable. Our observations confirmed that 30 min of integration were sufficient to observe ozone concentration profiles up to 10 km. Aerosol extinction and backscatter correction are estimated and applied. The aerosol backscatter correction profile using 287 and 299 nm as reference wavelengths is compared with that using 355 nm. The estimated statistical error is less than 5% at 1.5 km and 10% at 2.6 km. Comparisons with the operational carbon-iodine type chemical ozonesondes demonstrate 20% overestimation of the ozone profiles by the DIAL technique.

Nakazato, Masahisa; Nagai, Tomohiro; Sakai, Tetsu; Hirose, Yasuo

2007-04-01

114

Tracking aerosol plumes: lidar, modeling, and in situ measurement  

NASA Astrophysics Data System (ADS)

The authors report on recent progress of on-going research at Arizona State University for tracking aerosol plumes using remote sensing and modeling approaches. ASU participated in a large field experiment, Joint Urban 2003, focused on urban and suburban flows and dispersion phenomena which took place in Oklahoma City during summer 2003. A variety of instruments were deployed, including two Doppler-lidars. ASU deployed one lidar and the Army Research deployed the other. Close communication and collaboration has produced datasets which will be available for dual Doppler analysis. The lidars were situated in a way to provide insight into dynamical flow structures caused by the urban core. Complementary scanning by the two lidars during the July 4 firework display in Oklahoma City demonstrated that smoke plumes could be tracked through the atmosphere above the urban area. Horizontal advection and dispersion of the smoke plumes were tracked on two horizontal planes by the ASU lidar and in two vertical planes with a similar lidar operated by the Army Research Laboratory. A number of plume dispersion modeling systems are being used at ASU for the modeling of plumes in catastrophic release scenarios. Progress using feature tracking techniques and data fusion approaches is presented for utilizing single and dual radial velocity fields from coherent Doppler lidar to improve dispersion modeling. The possibility of producing sensor/computational tools for civil and military defense applications appears worth further investigation. An experiment attempting to characterize bioaerosol plumes (using both lidar and in situ biological measurements) associated with the application of biosolids on agricultural fields is in progress at the time of writing.

Calhoun, Ron J.; Heap, Robert; Sommer, Jeffrey; Princevac, Marko; Peccia, Jordan; Fernando, H.

2004-09-01

115

The Refurbishment and Upgrade of the Atmospheric Radiation Measurement Raman Lidar  

SciTech Connect

The Atmospheric Radiation Measurement Program (ARM) Climate Research Facility (ACRF) Raman lidar (CARL) is an autonomous, turn-key system that profiles water vapor, aerosols, and clouds throughout the diurnal cycle for days without attention (Goldsmith et al. 1998). CARL was first deployed to the Southern Great Plains CRF during the summer of 1996 and participated in the 1996 and 1997 water vapor intensive operational periods (IOPs). Since February 1998, the system has collected over 38,000 hrs of data (equivalent of almost 4.4 years), with an average monthly uptime of 62% during this time period. This unprecedented performance by CARL makes it the premier operational Raman lidar in the world. Unfortunately, CARL began degrading in early 2002. This loss of sensitivity, which affected all observed variables, was very gradual and thus was not identified until the autumn of 2003. Analysis of the data suggested the problem was not associated with the laser or transmit portion of the system, but rather in the detection subsystem, as both the background values and the peak signals showed a marked decreases over this time period. The loss of sensitivity of a factor of 2-4, depending on the channel, resulted in higher random error in the retrieved products, such as the aerosol backscatter coefficient and water vapor mixing ratio. Figure 1 shows the random error at 2 km for aerosol backscatter coefficient (top) and water vapor mixing ratio (middle), in terms of percent of the signal for both average daytime (red) and nighttime (blue) data from 1998 to 2005. The seasonal variation of water vapor is easily seen in the random error in the water vapor mixing ratio data. The loss of sensitivity also affected the maximum range of the usable data, as illustrated by the dramatic decrease in the maximum height seen in the water vapor mixing ratio data (bottom). This degradation, which results in much larger random errors, greatly hinders the analysis of data sets such as the Aerosol IOP (March 2003) and the AIRS Water Vapor Experiment (December 2003). The degradation and its impact on the Aerosol IOP analysis are reported in Ferrare et al. 2005.

Turner, D.D.; Goldsmith, J.E.M.

2005-03-18

116

Performance modeling of daytime Raman lidar systems for profiling atmospheric water vapor  

NASA Technical Reports Server (NTRS)

We describe results from a comprehensive computer model developed to guide optimization of an ultraviolet Raman lidar system for measuring daytime profiles of atmospheric water vapor. Daytime measurements present added challenges because of the difficulties inherent in detecting Raman signals against solar backgrounds. We are pursuing two concepts for optimizing the daytime performance of a Raman lidar system. The first involves operating the system in the solar blind region of the ultraviolet spectrum. The second concept involves operation of the system in a narrowband, narrow field-of-view mode. Calculations for lidar systems based on both concepts are presented.

Goldsmith, J. E. M.; Ferrare, Richard A.

1992-01-01

117

Airborne high spectral resolution lidar for profiling aerosol optical properties.  

PubMed

A compact, highly robust airborne High Spectral Resolution Lidar (HSRL) that provides measurements of aerosol backscatter and extinction coefficients and aerosol depolarization at two wavelengths has been developed, tested, and deployed on nine field experiments (over 650 flight hours). A unique and advantageous design element of the HSRL system is the ability to radiometrically calibrate the instrument internally, eliminating any reliance on vicarious calibration from atmospheric targets for which aerosol loading must be estimated. This paper discusses the design of the airborne HSRL, the internal calibration and accuracy of the instrument, data products produced, and observations and calibration data from the first two field missions: the Joint Intercontinental Chemical Transport Experiment--Phase B (INTEX-B)/Megacity Aerosol Experiment--Mexico City (MAX-Mex)/Megacities Impacts on Regional and Global Environment (MILAGRO) field mission (hereafter MILAGRO) and the Gulf of Mexico Atmospheric Composition and Climate Study/Texas Air Quality Study II (hereafter GoMACCS/TexAQS II). PMID:19104525

Hair, Johnathan W; Hostetler, Chris A; Cook, Anthony L; Harper, David B; Ferrare, Richard A; Mack, Terry L; Welch, Wayne; Isquierdo, Luis Ramos; Hovis, Floyd E

2008-12-20

118

Analysis and Calibration of CRF Raman Lidar Cloud Liquid Water Measurements  

SciTech Connect

The Atmospheric Radiation Measurement (ARM) Raman lidar (RL), located at the Southern Great Plains (SGP) Climate Research Facility (CRF), is a unique state-of-the-art active remote sensor that is able to measure profiles of water vapor, aerosol, and cloud properties at high temporal and vertical resolution throughout the diurnal cycle. In October 2005, the capability of the RL was extended by the addition of a new detection channel that is sensitive to the Raman scattering of liquid water. This new channel permits the system, in theory, to measure profiles of liquid water content (LWC) by the RL. To our knowledge, the ARM RL is the only operation lidar with this capability. The liquid water Raman backscattering cross-section is a relatively weak and spectrally broad feature, relative to the water vapor Raman backscatter signal. The wide bandpass required to achieve reasonable signal-to-noise in the liquid water channel essentially eliminates the ability to measure LWC profiles during the daytime in the presence of large solar background, and thus all LWC observations are nighttime only. Additionally, the wide bandpass increases the probability that other undesirable signals, such as fluorescence from aerosols, may contaminate the observation. The liquid water Raman cross-section has a small amount of overlap with the water vapor Raman cross-section, and thus there will be a small amount of ‘cross-talk’ between the two signals, with water vapor contributing a small amount of signal to the LWC observation. And finally, there is significant uncertainty in the actual strength of the liquid water Raman cross-section in the literature. The calibrated LWC profiles, together with the coincident cloud backscatter observations also made by the RL, can be used to derive profiles of cloud droplet effective radius. By combining these profiles of effective radius in the lower portion of the cloud with the aerosol extinction measurements made below the cloud by the RL, the first aerosol indirect effect can be investigated using a single instrument, thereby reducing the uncertainty associated with aligning the different sampling periods and fields of view of multiple instruments. We have applied a “first principles” calibration to the LWC profiles. This approach requires that the relative differences in optical efficiency between the water vapor and liquid water channels be known; this relative difference is easily computed using the efficiency values of the beam splitters and interference filters in the lidar that were provided by the vendors of these components. The first principles approach then transfers the calibration from the water vapor mixing ratio to the LWC using the difference in the optical efficiency and an interpolated value of the liquid water Raman cross section from the literature, and the better established water vapor Raman cross section. After accounting for all known error sources, the vertical integral of LWC was compared against a similar value retrieved from a co-located ground-based infrared radiometer. The RL and infrared radiometer have significantly different fields of view; thus to compare the two sensors the data were averaged to 5 min intervals where only cloudy samples were included in the average of each. While there is fair scatter in the data (r=0.47), there is also a clear indication of a positive correlation between the infrared and the RL values. The value of the slope of the regression is 0.49, which indicates a tendency of the RL measurements to underestimate the total liquid amount with respect to the infrared retrieval. Research continues to investigate the source of the bias, but the most likely candidate is the large uncertainty in the liquid water Raman cross-section as there have been no direct measurements made of this parameter at the lidar’s laser wavelength of 355 nm. The calibrated LWC profile was then used together with the cloud backscatter coefficient profile from the RL to derive profiles of cloud droplet effective radius and cloud droplet number density. These profiles o

Turner, D.D.

2007-10-31

119

Compact Efficient Lidar Receiver for Measuring Atmospheric Aerosols  

NASA Technical Reports Server (NTRS)

A small, light weight, and efficient aerosol lidar receiver was constructed and tested. Weight and space savings were realized by using rigid optic tubes and mounting cubes to package the steering optics and detectors in a compact assembly. The receiver had a 1064nm channel using an APD detector. The 532nm channel was split (90/10) into an analog channel (90%) and a photon counting channel (10%). The efficiency of the 1064nm channel with optical filter was 44.0%. The efficiency of the analog 532nm channel was 61.4% with the optical filter, and the efficiency of the 532nm photon counting channel was 7.6% with the optical filter. The results of the atmospheric tests show that the detectors were able to consistently return accurate results. The lidar receiver was able to detect distinct cloud layers, and the lidar returns also agreed across the different detectors. The use of a light weight fiber-coupled telescope reduced weight and allowed great latitude in detector assembly positioning due to the flexibility enabled by the use of fiber optics. The receiver is now ready to be deployed for aircraft or ground based aerosol lidar measurements.

Gili, Christopher; De Young, Russell

2006-01-01

120

Scanning Mobile Lidar for Aerosol Tracking and Biological Aerosol Identification  

Microsoft Academic Search

Optical properties of non-biological aerosols containing aromatic hydrocarbons, such as industrial chemicals and engine exhausts, have already been thoroughly studied using remote sensing techniques. However, because of their complex composition and characteristics, the identification of biological aerosols, such as fungi, pollen and bacteria that are present in the environment remains a rather difficult task. The collection of information on both

Tingyao He; Klemen Bergant; Andrej Filipcic; Biagio Forte; Fei Gao; Samo Stanic; Darko Veberic; Marko Zavrtanik

2010-01-01

121

Performance modeling of ultraviolet Raman lidar systems for daytime profiling of atmospheric water vapor  

NASA Technical Reports Server (NTRS)

We describe preliminary results from a comprehensive computer model developed to guide optimization of a Raman lidar system for measuring daytime profiles of atmospheric water vapor, emphasizing an ultraviolet, solar-blind approach.

Ferrare, R. A.; Whiteman, D. N.; Melfi, S. H.; Goldsmith, J. E. M.; Bisson, S. E.; Lapp, M.

1991-01-01

122

AVS LIDAR for Detecting Obstacles Inside Aerosol  

Microsoft Academic Search

The ability to detect obstacles or ground inside aerosols that are small particles suspended in the atmosphere is a highly sought-after feature for numerous helicopter operations. Helicopter pilots need visual assistance for safe flight and landing during white-out conditions that can be produced by natural weather phenomenon such as fog or a snow storm, or can be formed by circling

Xiang Zhu; Philip Church; M. Labrie

2010-01-01

123

Tropospheric aerosol observations by Lidar at Naqu  

NASA Astrophysics Data System (ADS)

The Tibet plateau is characterized with its own special highland climate environment. In this paper, the temporal vertical profiles of aerosol extinction/backscattering coefficients, the boundary layer height (BLH) and cloud height during the CAMP-Tibet 2003 autumn and 2004 spring session observations at Naqu BJ site, Tibet are determined with ancillary meteorological parameters, and compared with data at Bejing site.

Yang, Hui; Liu, Wenqing; Lu, Yihuai; Liu, Jianguo; Wen, Qingnong; Wu, Dexia; Liu, Cheng; Takeuchi, Nobuo

2005-05-01

124

Aerosol Optical Depth Climatology Derived from Micropulse Lidar Data at Various ARM Sites World-wide  

NASA Astrophysics Data System (ADS)

Micropulse Lidar (MPL) systems have been running at all US Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) sites including 5 permanent and 2 mobile facilities. The locations of the sites represent a broad range of climate conditions around the world [http://www.arm.gov/sites]. Aerosol optical depth (AOD) is a measure of the extinction of solar radiation due to aerosols; liquid and solid particles suspended in the air from natural or man-made sources. In the absence of clouds, the MPL, operating at 532 nm, produces profiles of atmospheric scattering that result from aerosols (Mie-scattering) and molecules (Rayleigh-scattering). In combination with AOD data from the nearly co-located multifilter rotating shadowband radiometer (MFRSR), these data can be used to calculate profiles of AOD. The raw data used in this study are averaged in time for 30 seconds and 30 meters in altitude. MPL backscatter observations at the DOE ARM sites from 2007 through 2010 have been examined and used in this AOD climatology. The AOD values at Southern Great Plains (SGP) site are also compared with the corresponding values obtained from a nearly co-located Raman Lidar (RL) operating at 355 nm. The comparison shows good agreement. A multi-year vertical profile of AOD climatology at different ARM sites, including diurnal and seasonal variability will be presented. These results are expected to be of significant importance to the scientific community to understand the aerosol properties and the boundary layer dynamics better as well as to improve global climate models by better incorporating the aerosol radiative effects.

Kafle, D. N.; Coulter, R.

2011-12-01

125

Comparison of measurements by the NASA/GSFC scanning raman lidar and the DOE/ARM CART raman lidar  

NASA Technical Reports Server (NTRS)

Latent heat transfer through evaporation and condensation of water vapor is the most important energy transport mechanism in the atmosphere. In addition, water vapor is the most active greenhouse gas. Any global warming scenario must take accurate account of the spatial and temporal variation of water vapor in order to account for both of these effects. Due to the great importance of water vapor in atmospheric radiation studies, specific intensive operations periods (IOPs) have been hosted by the Department of Energy's Atmospheric Radiation Measurements (ARM) program. One of the goals of these IOPs has been to determine the quality of and explain any discrepancies among a wide variety of water vapor measuring instruments. Raman lidar systems developed by NASA/Goddard Space Flight Center and DOE/Sandia National Laboratories have participated in the two Water Vapor IOPs (WVIOPs) held at the Southern Great Plains (SGP) Cloud and Radiation Testbed Site (CART) site during 1996 (WVIOP1) and 1997 (WVIOP2). Detailed comparisons of these two systems is ongoing but this effort has already resulted in numerous improvements in design and data analysis for both lidar systems.

Whiteman, David; Turner, David; Evans, Keith; Demoz, Belay; Melfi, Harvey; Schwemmer, Geary; Cadirola, Martin; Ferrare, Richard; Goldsmith, John; Tooman, Tim; Wise, Stacy

1998-01-01

126

Simulations of the Observation of Clouds and Aerosols with the Experimental Lidar in Space Equipment System  

Microsoft Academic Search

We carried out a simulation study for the observation of clouds and aerosols with the Japanese Experimental Lidar in Space Equipment (ELISE), which is a two-wavelength backscatter lidar with three detection channels. The National Space Development Agency of Japan plans to launch the ELISE on the Mission Demonstrate Satellite 2 (MDS-2). In the simulations, the lidar return signals for the

Zhaoyan Liu; Peter Voelger; Nobuo Sugimoto

2000-01-01

127

Lidar validation of SAGE II aerosol measurements after the 1991 Mount Pinatubo eruption  

E-print Network

Lidar validation of SAGE II aerosol measurements after the 1991 Mount Pinatubo eruption Juan Carlos the possibility of filling the vertical gaps using lidar data. We compare every coincident backscattering measurement (at a wavelength of 0.694 mm) from two lidars, at Mauna Loa, Hawaii (19.5°N, 155.6°W

Robock, Alan

128

Measurement of the Lidar Ratio for Atmospheric Aerosols using a 180-Backscatter Nephelometer  

E-print Network

Measurement of the Lidar Ratio for Atmospheric Aerosols using a 180°-Backscatter Nephelometer, and Environmental Optics Doherty, S.J., T.L. Anderson, and R.J. Charlson, Measurement of the lidar ratio-1832. #12;1 Abstract: Laser radar (lidar) can be used to estimate atmospheric extinction coefficients due

129

Novel Co:MgF2 lidar for aerosol profiler  

NASA Technical Reports Server (NTRS)

Lidars are of great interest because of their unique capabilities in remote sensing applications in sounding of the atmosphere, meteorology, and climatology. In this small business innovative research (SBIR) phase II program, laser sources including Co:MgF2, CTH:YAG, CTH:YSGG, CT:YAG, and Er:Glass were evaluated. Modulator of fused silica and TeO2 materials with Brewster's angle end faces were used with these lasers as acousto-optical (AO) Q-switches. A higher hold-off energy and hence a higher Q-switched energy was obtained by using a high power RF driver. The report provides performance characteristics of these lasers. The tunable (1.75-2.50 microns) Co:MgF2 laser damaged the TeO2 Q-switch cell. However, the CTH:YAG laser operating at 2.09 microns provided output energy of over 300 mJ/p in 50 ns pulse width using the fused silica Q-switch. This Q-switched CTH:YAG laser was used in a breadboard vertical aerosol profiler. A 40 cm diameter telescope, InSb and InGaAs detectors were used in the receiver. The data obtained using this lidar is provided in the report. The data shows that the eye safe lidar using CTH:YAG laser for the vertical aerosol density and range measurements is the viable approach.

Acharekar, M. A.

1993-01-01

130

Feasibility Study For A Spaceborne Ozone/Aerosol Lidar System  

NASA Technical Reports Server (NTRS)

Because ozone provides a shield against harmful ultraviolet radiation, determines the temperature profile in the stratosphere, plays important roles in tropospheric chemistry and climate, and is a health risk near the surface, changes in natural ozone layers at different altitudes and their global impact are being intensively researched. Global ozone coverage is currently provided by passive optical and microwave satellite sensors that cannot deliver high spatial resolution measurements and have particular limitations in the troposphere. Vertical profiling DIfferential Absorption Lidars (DIAL) have shown excellent range-resolved capabilities, but these systems have been large, inefficient, and have required continuous technical attention for long term operations. Recently, successful, autonomous DIAL measurements have been performed from a high-altitude aircraft (LASE - Lidar Atmospheric Sensing Experiment), and a space-qualified aerosol lidar system (LITE - Laser In-space Technology Experiment) has performed well on Shuttle. Based on the above successes, NASA and the Canadian Space Agency are jointly studying the feasibility of developing ORACLE (Ozone Research with Advanced Cooperative Lidar Experiments), an autonomously operated, compact DIAL instrument to be placed in orbit using a Pegasus class launch vehicle.

Campbell, Richard E.; Browell, Edward V.; Ismail, Syed; Dudelzak, Alexander E.; Carswell, Allan I.; Ulitsky, Arkady

1997-01-01

131

A new cloud and aerosol layer detection method based on micropulse lidar measurements  

E-print Network

A new cloud and aerosol layer detection method based on micropulse lidar measurements Chuanfeng algorithm to detect aerosols and clouds based on micropulse lidar measurements. A semidiscretization is then introduced. Combined with empirical threshold values, we determine if the signal waves indicate clouds

Li, Zhanqing

132

Aerosol classification using airborne High Spectral Resolution Lidar measurements - methodology and examples  

Microsoft Academic Search

The NASA Langley Research Center (LaRC) airborne High Spectral Resolution Lidar (HSRL) on the NASA B200 aircraft has acquired extensive datasets of aerosol extinction (532 nm), aerosol optical thickness (AOT) (532 nm), backscatter (532 and 1064 nm), and depolarization (532 and 1064 nm) profiles during 18 field missions that have been conducted over North America since 2006. The lidar measurements

S. P. Burton; R. A. Ferrare; C. A. Hostetler; J. W. Hair; R. R. Rogers; M. D. Obland; C. F. Butler; A. L. Cook; D. B. Harper; K. D. Froyd

2011-01-01

133

Ice and Aerosol Observations by the NASA Langley Airborne High Spectral Resolution Lidar during ARCTAS  

Microsoft Academic Search

The NASA Langley Airborne High Spectral Resolution Lidar (HSRL) participated in the ARCTAS field mission, measuring aerosol extinction at 532 nm using the HSRL technique and aerosol backscatter and depolarization at both 532 nm and 1064 nm. The ability to measure intensive parameters like depolarization, lidar ratio (extinction-to-backscatter ratio) and a ratio of depolarization at two different wavelengths gives some

S. P. Burton; R. A. Ferrare; C. A. Hostetler; J. W. Hair; L. D. Ziemba; A. H. Omar; A. Cook; D. Harper; M. D. Obland; R. Rogers; N. O'Neill

2009-01-01

134

Aerosol optical properties in the ABL over arctic sea ice from airborne aerosol lidar measurements  

NASA Astrophysics Data System (ADS)

Between 2009 and 2013 aerosols, sea ice properties and meteorological variables were measured during several airborne campaigns covering a wide range of the western Arctic Ocean. The campaigns were carried out with the aircraft Polar 5 of the German Alfred-Wegener-Institute (AWI) during spring and summer periods. Optical properties of accumulation mode aerosol and clouds were measured with the nadir looking AMALi aerosol lidar covering the atmospheric boundary layer and the free troposphere up to 3000m, while dropsondes provided coincident vertical profiles of meteorological quantities. Based on these data we discuss the vertical distribution of aerosol backscatter in and above the atmospheric boundary layer and its dependence on relative humidity, dynamics and underlying sea ice properties. We analyze vertical profiles of lidar and coincident dropsonde measurements from various locations in the European and Canadian Arctic from spring and summer campaigns. Sea ice cover is derived from modis satellite and aircraft onboard camera images. The aerosol load in the arctic atmospheric boundary layer shows a high variability. Various meteorological parameters and in particular boundary layer properties are discussed with their respective influence on aerosol features. To investigate the effect of the frequency and size of open water patches on aerosol properties, we relate the profiles to the sea ice properties influencing the atmosphere in the upwind region.

Schmidt, Lukas; Neuber, Roland; Ritter, Christoph; Maturilli, Marion; Dethloff, Klaus; Herber, Andreas

2014-05-01

135

Columnar optical properties of tropospheric aerosol by combined lidar and sunphotometer measurements at Taipei, Taiwan  

Microsoft Academic Search

Vertical extinction profiles and columnar optical properties (optical depth, Angstrom exponent, lidar ratio, and particle depolarization) of aerosols were obtained by simultaneous measurements with a depolarization lidar and a sunphotometer at Taipei, Taiwan from February 2004 to January 2006. Columnar optical depths are high in Feb–Apr (0.61–0.75) by sunphotometer measurements. Lidar measurements show the contribution of aerosols in the free

Wei-Nai Chen; Yi-Wei Chen; Charles C. K. Chou; Shih-Yang Chang; Po-Hsiung Lin; Jen-Ping Chen

2009-01-01

136

Enhanced aerosol backscatter adjacent to tropical trade wind clouds revealed by satellite-based lidar  

Microsoft Academic Search

sensing with lidar offers several advantages over passive instruments, including range-resolved backscattered radian- ces, better cloud detection, and essentially no 3-D radiative cloud-adjacency effects when operated at night. Two notable studies used lidar to observe how aerosol properties change near cloud edge. The first and earliest study qualitatively reported an aerosol backscatter increase near two clouds from a ground-based lidar

Jason Lucas Tackett; Larry Di Girolamo

2009-01-01

137

Light scattering characteristics of various aerosol types derived from multiple wavelength lidar observations  

Microsoft Academic Search

The present study demonstrates the potential of a multiple-wavelength lidar for discriminating between several aerosol types on the basis of the wavelength dependence of the aerosol backscatter coefficient. The two-component lidar equation was solved under the assumption of similarity in the derived profiles of backscatter coefficients for each wavelength. It is shown that a three-wavelength lidar system operating at 300,

Yasuhiro Sasano; Edward V. Browell

1989-01-01

138

Lidar Investigation of Aerosol Pollution Distribution near a Coal Power Plant  

NASA Technical Reports Server (NTRS)

Using aerosol lidars with high spatial and temporal resolution with the possibility of real-time data interpretation can solve a large number of ecological problems related to the aerosol-field distribution and variation and the structure of convective flows. Significantly less expensive specialized lidars are used in studying anthropogenic aerosols in the planetary boundary layer. Here, we present results of lidar measurements of the mass-concentration field around a coal-fired power plant with intensive local aerosol sources. We studied the pollution evolution as a function of the emission dynamics and the presence of retaining layers. The technique used incorporates complex analysis of three types of lidar mapping: horizontal map of the aerosol field, vertical cross-section map, and a series of profiles along a selected path. The lidar-sounding cycle was performed for the time of atmosphere's quasi-stationarity.

Mitsev, TS.; Kolarov, G.

1992-01-01

139

Water vapor variance measurements using a Raman lidar  

NASA Technical Reports Server (NTRS)

Because of the importance of atmospheric water vapor variance, we have analyzed data from the NASA/Goddard Raman lidar to obtain temporal scales of water vapor mixing ratio as a function of altitude over observation periods extending to 12 hours. The ground-based lidar measures water vapor mixing ration from near the earth's surface to an altitude of 9-10 km. Moisture profiles are acquired once every minute with 75 m vertical resolution. Data at each 75 meter altitude level can be displayed as a function of time from the beginning to the end of an observation period. These time sequences have been spectrally analyzed using a fast Fourier transform technique. An example of such a temporal spectrum obtained between 00:22 and 10:29 UT on December 6, 1991 is shown in the figure. The curve shown on the figure represents the spectral average of data from 11 height levels centered on an altitude of 1 km (1 plus or minus .375 km). The spectra shows a decrease in energy density with frequency which generally follows a -5/3 power law over the spectral interval 3x10 (exp -5) to 4x10 (exp -3) Hz. The flattening of the spectrum for frequencies greater than 6x10 (exp -3) Hz is most likely a measure of instrumental noise. Spectra like that shown in the figure are calculated for other altitudes and show changes in spectral features with height. Spectral analysis versus height have been performed for several observation periods which demonstrate changes in water vapor mixing ratio spectral character from one observation period to the next. The combination of these temporal spectra with independent measurements of winds aloft provide an opportunity to infer spatial scales of moisture variance.

Evans, K.; Melfi, S. H.; Ferrare, R.; Whiteman, D.

1992-01-01

140

Raman lidar profiling of atmospheric water vapor: Simultaneous measurements with two collocated systems  

NASA Technical Reports Server (NTRS)

Raman lidar is a leading candidate for providing the detailed space- and time-resolved measurements of water vapor needed by a variety of atmospheric studies. Simultaneous measurements of atmospheric water vapor are described using two collocated Raman lidar systems. These lidar systems, developed at the NASA/Goddard Space Flight Center and Sandia National Laboratories, acquired approximately 12 hours of simultaneous water vapor data during three nights in November 1992 while the systems were collocated at the Goddard Space Flight Center. Although these lidar systems differ substantially in their design, measured water vapor profiles agreeed within 0.15 g/kg between altitudes of 1 and 5 km. Comparisons with coincident radiosondes showed all instruments agreed within 0.2 g/kg in this same altitude range. Both lidars also clearly showed the advection of water vapor in the middle troposphere and the pronounced increase in water vapor in the nocturnal boundary layer that occurred during one night.

Goldsmith, J. E. M.; Bisson, Scott E.; Ferrare, Richard A.; Evans, Keith D.; Whiteman, David N.; Melfi, S. H.

1994-01-01

141

Installation and calibration of the depolarization channel of the CANDAC Rayleigh-Mie-Raman Lidar in the Canadian High Arctic  

NASA Astrophysics Data System (ADS)

The Canadian Network for the Detection of Atmospheric Change (CANDAC) Rayleigh-Mie-Raman Lidar (CRL) was installed in the Canadian High Arctic at Eureka, Nunavut (80°N, 86°W) in 2008-2009. The remotely-operated system began with measurement capabilities for multi-wavelength aerosol extinction, water vapour mixing ratio, and tropospheric temperature profiles, as well as particulate density and colour ratio. In 2010, a new depolarisation channel was added, which provides measurements used to discern between ice crystal, liquid water, and aerosol returns. This is an important measurement capacity during the Arctic winter particularly due to the occurrence of tropospheric mixed-phase clouds. These clouds have significantly different radiative properties compared to the more usual ice clouds. Many depolarization-capable lidar systems use two separate detector channels: one for the component of the backscattered lidar return which is parallel to the transmitted laser light, and one for the component which is perpendicular. The CRL, instead, uses a rotating Glan-Thompson prism to allow perpendicular and parallel light through to a single PMT on alternate laser shots. This approach simplifies the calibration of the depolarization measurements because no corrections are needed to account for differences in sensitivity of two physically separate measurement channels. Details of the depolarization channel installation, calibration and some first results will be discussed.

McCullough, E. M.; Nott, G. J.; Duck, T. J.; Sica, R. J.; Drummond, J. R.

2010-12-01

142

Single-scattering albedo profiling of mixed Asian dust plumes with multiwavelength Raman lidar  

NASA Astrophysics Data System (ADS)

This study presents results of vertically-resolved single-scattering albedo of mixed Asian dust plumes, i.e. the total single-scattering albedo. The mixed Asian dust plumes are comprised of a mixture of pure dust particles and the non-dust part, e.g. urban/industrial pollution and smoke from biomass burning. The mixed Asian dust plumes were observed with multiwavelength Raman lidar which provides vertical profiles of particle backscatter coefficients at 355, 532, and 1064 nm and extinction coefficients at 355 and 532 nm. The optical data serve as input for an inversion algorithm that provides profiles of microphysical particle properties which subsequently are used for computing single-scattering albedo. This study presents results of dust plumes observed on 24 February 2004, 9 and 18 March 2004, 2 April 2004, and 24 February and 4 May 2005. The lidar measurements were carried out at Gwangju (35.10° N, 126.53° E), South Korea. The optical data of the mixed-dust plumes were separated into the pure dust content and the non-dust part. We used the linear particle depolarization ratio measured at 532 nm for this separation. The backscatter and extinction coefficients then were used to derive single-scattering albedo of the non-dust part of the mixed-dust plumes. The value 0.96 ± 0.02 at 532 nm for the single-scattering albedo of pure dust part was used. This value was obtained from single-scattering albedo of dust observed in various dust source regions. In another step the “total” single-scattering albedo of these mixed-dust plumes was calculated by using the optical depth of the dust and the non-dust part as weighting function. The single-scattering albedo of the non-dust particles of the mixed-dust plume varied from 0.63 to 0.93 for all observations presented in this study. The single-scattering albedo of the mixed-dust plumes was 0.71-0.95, and it was always higher than the single-scattering albedo of the non-dust part of the mixed-dust plumes. Single-scattering albedo varied with height on each measurement day. These differences seem to be quantitatively related to the degree of mixing of dust with urban pollution and the light-absorption properties of the pollution (non-dust) particles in these plumes which traveled along different transport pathways to the lidar site. The layer-mean lidar-derived single-scattering albedos of the examples shown in this study were compared to single-scattering albedo derived from AERONET (Aerosol Robotic Network) Sun/sky radiometer observations. This radiometer is located next to the lidar. The total layer-mean lidar-derived single-scattering albedos (at 532 nm) on 18 March and 2 April 2004, and on 24 February and 4 May 2005 were 0.91 ± 0.02, 0.90 ± 0.03, 0.91 ± 0.02, and 0.92 ± 0.02, respectively. The lidar-derived single-scattering albedos are similar to those based on the Sun/sky radiometer data if the different measurement wavelengths of the lidar and Sun/sky radiometer are taken account of.

Noh, Young M.

2014-10-01

143

Macrophysical Properties of Tropical Cirrus Clouds from the CALIPSO Satellite and from Ground-based Micropulse and Raman Lidars  

SciTech Connect

Lidar observations of cirrus cloud macrophysical properties over the U.S. Department of Energy Atmospheric Radiation Measurement (ARM) program Darwin, Australia site are compared from the Cloud-Aerosol Lidar and In- frared Pathfinder Satellite Observation (CALIPSO) satellite, the ground-based ARM micropulse lidar (MPL), and the ARM Raman lidar (RL). Comparisons are made using the subset of profiles where the lidar beam is not fully attenuated. Daytime measurements using the RL are shown to be relatively unaffected by the solar background and are therefore suited for checking the validity of diurnal cycles. RL and CALIPSO cloud fraction profiles show good agreement while the MPL detects significantly less cirrus, particularly during the daytime. Both MPL and CALIPSO observations show that cirrus clouds occur less frequently during the day than at night at all altitudes. In contrast, the RL diurnal cy- cle is significantly different than zero only below about 11 km; where it is the opposite sign (i.e. more clouds during the daytime). For cirrus geomet- rical thickness, the MPL and CALIPSO observations agree well and both datasets have signficantly thinner clouds during the daytime than the RL. From the examination of hourly MPL and RL cirrus cloud thickness and through the application of daytime detection limits to all CALIPSO data we find that the decreased MPL and CALIPSO cloud thickness during the daytime is very likely a result of increased daytime noise. This study highlights the vast im- provement the RL provides (compared to the MPL) in the ARM program's ability to observe tropical cirrus clouds as well as a valuable ground-based lidar dataset for the validation of CALIPSO observations and to help im- prove our understanding of tropical cirrus clouds.

Thorsen, Tyler J.; Fu, Qiang; Comstock, Jennifer M.; Sivaraman, Chitra; Vaughan, Mark A.; Winker, D.; Turner, David D.

2013-08-27

144

Airborne lidar measurements of El Chichon stratospheric aerosols  

NASA Technical Reports Server (NTRS)

A NASA Electra airplane, outfitted with a lidar system, was flown in January to February 1983 between the latitudes of 27 deg N and 76 deg N. One of the primary purposes of this mission was to determine the spatial distribution and aerosol characteristics of the El Chichon-produced stratospheric material. This report presents the lidar data from that flight mission. Representative profiles of lidar backscatter ratio, plots of the integrated backscattering function versus latitude, and contours of backscatter mixing ratio versus altitude and latitude are given. It addition, tables containing numerical values of the backscatter ratio and backscattering function versus altitude are supplied for each profile. The largest amount of material produced by the El Chichon eruptions of late March to early April 1982, which was measured by this flight, resided between 35 deg N and 52 deg N. Peak backscatter ratios at a wavelength of 0.6943 micro m decreased from 8 to 10 at the lower latitudes to 3 at the higher latitudes. Backscatter ratio profiles taken while crossing the polar vortex show that the high-altitude material from El Chichon arrived at the north polar region sometime after the winter polar vortex was established. This report presents the results of this mission in a ready-to-use format for atmospheric and climatic studies.

Mccormick, M. P.; Osborn, M. T.

1985-01-01

145

Airborne lidar measurements of El Chichon stratospheric aerosols, January 1984  

NASA Technical Reports Server (NTRS)

A lidar-equipped NASA Electra aircraft was flown in January 1984 between the latitude of 38 and 90 deg N. One of the primary purposes of this mission was to determine the spatial distribution and aerosol characteristics of El Chichon produced stratospheric material. Lidar data from that portion of the flight mission between 38 deg N and 77 deg N is presented. Representative profiles of lidar backscatter ratio, a plot of the integral backscattering function versus latitude, and contours of backscatter mixing ratio versus altitude and latitude are given. In addition, tables containing numerical values of the backscatter ratio and backscattering function versus altitude are applied for each profile. These data clearly show that material produced by the El Chichon eruptions of late March-early April 1982 had spread throughout the latitudes covered by this mission, and that the most massive portion of the material resided north of 55 deg N and was concentrated below 17 km in a layer that peaked at 13 to 15 km. In this latitude region, peak backscatter ratios at a wavelength of 0.6943 microns were approximately 3 and the peak integrated backscattering function was about 15 X 10 to the -4/sr corresponding to a peak optical depth of approximately 0.07. This report presents the results of this mission in a ready-to-use format for atmospheric and climatic studies.

Mccormick, M. Patrick; Osborn, M. T.

1987-01-01

146

Airborne lidar measurements of El Chichon stratospheric aerosols, May 1983  

NASA Technical Reports Server (NTRS)

An experimental survey flight to determine the spatial distribution and aerosol characteristics of the El Chichon-produced stratospheric aerosol was conducted in May 1983. The mission included several different sensors flown abroad the NASA Convair 990 at latitudes between 72 deg. and 56 deg. S. This report presents the lidar data from that flight mission. Representative profiles of lidar backscatter ratio, plots of integrated backscattering function versus latitude, and contours of backscatter mixing ratio versus altitude and latitude are given. In addition, tables containing numerical values of the backscatter ratio and backscattering function versus altitude are supplied for each profile. By May 1983, material produced by the El Chichon eruptions of late March-early April 1982 had spread throughout the latitudes covered by this mission. However, the most massive portion of the material resided north of 33 deg. N and was concentrared below 21 km. In this latitude region (33 deg. N to 72 deg. N), peak backscatter ratios at a wavelength of 0.6943 microns varied between 3.5 and 4.5, and the peak integratred backscattering function was about 18 X 10 to the -4 power/sr, corresponding to a peak optical depth calculated to be approximately 0.08. This report presents the results of this mission in a ready-to-use format for atmospheric and climatic studies.

Mccormick, M. P.; Osborn, M. T.

1986-01-01

147

Continuous lidar measurements of stratospheric aerosols and ozone after the Pinatubo eruption Part II: Time evolution of ozone profiles and of aerosol properties  

SciTech Connect

This paper presents the results of stratospheric ozone measurements made from Aug 1991 to Dec 1992, by means of differential absorption lidar (DIAL) and an aerosol lidar, above L'Aquila, Italy. The aerosol lidar was necessary to allow separation of the backscatter signal from the aerosol load in the stratosphere from the eruption of Mt. Pinatubo. Results of the time development of the aerosol loading, and size distribution are also presented.

D'Altorio, A.; Visconti, G. (Universita degli Studi - L'Aquila, L'Aquila (Italy)); Masci, F.; Rizi, V.; Boschi, E. (Instituto Nazional di Geofisica, Roma (Italy))

1993-12-23

148

A short-standoff bistatic lidar system for aerosol cloud backscatter and fluorescence cross section, and depolarization ratio measurement  

NASA Astrophysics Data System (ADS)

We have designed a short-standoff bistatic lidar system, used for the direct measurement of the optical backscatter at 355-nm and 1064-nm and laser induced fluorescence (LIF) cross sections as well as depolarization ratio of aerosols inside a vacuum sealed, aerosol flow chamber. The 355- and 1064-nm beams are sent through the aerosol chamber at an angle of ~2° with respect to the field of view of the receiver optics to ensure that measurements reflect true backscatter. This bistatic lidar configuration naturally defines a limited region in space where the laser beams and the receiver field of view overlap, a region that can be easily quantified using a standard calibration procedure. Our technique also takes advantage of a specially designed vacuum sealed, aerosol flow chamber that provides a well-mixed, uniform aerosol distribution over the region of sensitivity. Both modeling results and experimental measurements confirm that little particle loss is observed inside the aerosol flow chamber. A TSI aerodynamic particle sizer (APS) is used to measure the aerosol concentration in the chamber, and the N2 concentration can be calculated using the measured temperature and pressure of the air inside the chamber. Optical backscatter and LIF cross sections are determined by comparing the measured elastic and LIF signals with the N2 Raman scattering signal from the same sample volume, a technique which eliminates the need for absolute radiometric calibration of the system. Instead, all detectors in the system are calibrated relative to the N2 Raman channel and the unknown aerosol cross sections are determined by taking the ratio of the backscatter (or LIF) signals to the Raman signal and multiplying by the well-known Raman cross section of N2. Particulate population depolarization parameters are determined by measuring the rejected polarized light from a Glan Laser prism polarizer and comparing those intensity measurements with that of the direct backscatter intensity. This work will focus on particle specific optical backscatter cross-sections and depolarization ratios for atmospherically relevant particle populations including Arizona road dust, black carbon, ammonium sulfate, and sodium chloride. Preliminary results of the absolute scattering cross-section and polarization parameters will be presented. Sandia National Laboratories is a multi-program laboratory operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Glen, C.; Schmitt, R. L.; Sickafoose, S.; Johnson, M. S.; Shagam, R.; Reichardt, T.; Sanchez, A.; Servantes, B.

2012-12-01

149

Aerosol transport in the California Central Valley observed by airborne lidar.  

PubMed

An aerosol lidar system was deployed on the NASA DC-8 and used to measure aerosol vertical profiles in the California Central Valley. The nadir-pointing Nd:YAG lidar operated at 532 and 1064 nm at 20 Hz. The resulting aerosol profiles were plotted in a unique three-dimensional format that allowed the visual observation of the aerosol scattering ratio profiles, the valley topography, and corresponding backward trajectory air masses. The accumulation of aerosols from the Bakersfield area can be seen in the southern end of the valley due to topography and prevailing winds. PMID:16294873

De Young, Russell J; Grant, William B; Severance, Kurt

2005-11-01

150

Optical autocovariance direct detection lidar for simultaneous wind, aerosol, and chemistry profiling from ground, air, and space platforms  

NASA Astrophysics Data System (ADS)

Optical Autocovariance Wind Lidar (OAWL) is a new direct-detection interferometric Doppler lidar approach that inherently enables simultaneous acquisition of multiple-wavelength High Spectral Resolution Lidar calibrated aerosol profiles (OA-HSRL). Unlike other coherent and direct detection Doppler systems, the receiver is self referencing; no specific optical frequency lock is required between the receiver and transmitter. This property facilitates frequency-agile modalities such as DIAL. Because UV laser wavelengths are accommodated, a single transmitter can simultaneously support winds, Raman, fluorescence, DIAL, and HSRL receiver channels, each sampling identical spatial and temporal volumes. LOS species flux measurements are acquired without the usual spatial and temporal sampling errors (or cost, volume, mass, power, and logistical issues) incurred by separate lidar systems, or lidars in combination with other remote or in-situ sensors. A proof of concept (POC) OAWL system has been built and demonstrated at Ball, and OAHSRL POC is in progress. A robust multi-wavelength, field-widened OAWL/OA-HSRL system is under development with planned airborne demonstration from a WB-57 in late 2010. Detailed radiometric and dynamic models have been developed to predict performance in both airborne and space borne scenarios. OA theory, development, demonstration status, advantages, limitations, space and airborne performance, and combined measurement synergies are discussed.

Grund, Christian J.; Howell, James; Pierce, Robert; Stephens, Michelle

2009-05-01

151

Polar winter cloud depolarization measurements with the CANDAC Rayleigh-Mie-Raman Lidar  

NASA Astrophysics Data System (ADS)

Clouds introduce a significant positive forcing to the Arctic radiation budget and this is strongest during the polar winter when shortwave radiation is absent (Intrieri et al., 2002). The amount of forcing depends on the occurrence probability and optical depth of the clouds as well as the cloud particle phase (Ebert and Curry 1992). Mixed-phase clouds are particularly complex as they involve interactions between three phases of water (vapour, liquid and ice) coexisting in the same cloud. Although significant progress has been made in characterizing wintertime Arctic clouds (de Boer et al., 2009 and 2011), there is considerable variability in the relative abundance of particles of each phase, in the morphology of solid particles, and in precipitation rates depending on the meteorology at the time. The Canadian Network for the Detection of Atmospheric Change (CANDAC) Rayleigh-Mie-Raman Lidar (CRL) was installed in the Canadian High Arctic at Eureka, Nunavut (80°N, 86°W) in 2008-2009. The remotely-operated system began with measurement capabilities for multi-wavelength aerosol extinction, water vapour mixing ratio, and tropospheric temperature profiles, as well as backscatter cross section coefficient and colour ratio. In 2010, a new depolarization channel was added. The capability to measure the polarization state of the return signal allows the characterization of the cloud in terms of liquid and ice water content, enabling the lidar to probe all three phases of water in these clouds. Lidar depolarization results from 2010 and 2011 winter clouds at Eureka will be presented, with a focus on differences in downwelling radiation between mixed phase clouds and ice clouds. de Boer, G., E.W. Eloranta, and M.D. Shupe (2009), Arctic mixed-phase stratiform cloud properties from multiple years of surface-based measurements at two high-latitude locations, Journal of Atmospheric Sciences, 66 (9), 2874-2887. de Boer, G., H. Morrison, M. D. Shupe, and R. Hildner (2011), Evidence of liquid dependent ice nucleation in high-latitude stratiform clouds from surface remote sensors, Geophysical Research Letters, 38, L01803. Ebert, EE and J.A .Curry (1992), A parameterization of ice cloud optical properties for climate models, Journal of Geophysical Research 97:3831-3836. Intrieri JM, Fairall CW, Shupe MD, Persson POG, Andreas EL, Guest PS, Moritz RE. 2002. An annual cycle of Arctic surface cloud forcing at SHEBA. Journal of Geophysical Research 107 NO. C10, 8039 . Noel, V., H. Chepfer, M. Haeffelin, and Y. Morille (2006), Classification of ice crystal shapes in midlatitude ice clouds from three years of lidar observations over the SIRTA observatory. Journal of the Atmospheric Sciences, 63:2978 - 2991.

McCullough, E. M.; Nott, G. J.; Duck, T. J.; Sica, R. J.; Doyle, J. G.; Pike-thackray, C.; Drummond, J. R.

2011-12-01

152

Water Vapor Measurements by Howard University Raman Lidar during the WAVES 2006 Campaign  

NASA Technical Reports Server (NTRS)

Retrieval of water vapor mixing ratio using the Howard University Raman Lidar is presented with emphasis on three aspects: i) performance of the lidar against collocated radiosondes and Raman lidar, ii) investigation of the atmospheric state variables when poor agreement between lidar and radiosondes values occurred and iii) a comparison with satellite-based measurements. The measurements were acquired during the Water Vapor Validation Experiment Sondes/Satellites 2006 field campaign. Ensemble averaging of water vapor mixing ratio data from ten night-time comparisons with Vaisala RS92 radiosondes shows on average an agreement within 10 % up to approx. 8 km. A similar analysis of lidar-to-lidar data of over 700 profiles revealed an agreement to within 20 % over the first 7 km (10 % below 4 km). A grid analysis, defined in the temperature - relative humidity space, was developed to characterize the lidar - radiosonde agreement and quantitatively localizes regions of strong and weak correlations as a function of altitude, temperature or relative humidity. Three main regions of weak correlation emerge: i) regions of low relative humidity and low temperature, ii) moderate relative humidity at low temperatures and iii) low relative humidity at moderate temperatures. Comparison of Atmospheric InfraRed Sounder and Tropospheric Emission Sounder satellites retrievals of moisture with that of Howard University Raman Lidar showed a general agreement in the trend but the formers miss a lot of the details in atmospheric structure due to their low resolution. A relative difference of about 20 % is usually found between lidar and satellites measurements.

Adam, M.; Demoz, B. B.; Whiteman, D. N.; Venable, D. D.; Joseph E.; Gambacorta, A.; Wei, J.; Shephard, M. W.; Miloshevich, L. M.; Barnet, C. D.; Herman, R. L.; Fitzgibbon, J.; Connell, R.

2009-01-01

153

Assessing spaceborne lidar detection and characterization of aerosols near clouds using coincident airborne lidar and other measurements  

NASA Astrophysics Data System (ADS)

The objectives are to 1) evaluate potential shortcomings in the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) aerosol height detection concerning specific biomass burning smoke events informed by airborne High Spectral Resolution Lidar (HSRL) in different cloud environments and 2) study the lidar-derived atmospheric parameters in the vicinity of clouds for the cases where smoke is within or above clouds. In the case of light absorbing aerosols like biomass burning smoke, studies show that the greater the cloud cover below the aerosols, the more likely the aerosols are to heat the planet. An accurate aerosol height assumption is also crucial to a correct retrieval of aerosol chemical composition from passive space-based measurements (through the Single Scattering Albedo (SSA) and aerosol absorption coefficient, as exemplified by aerosol retrievals using the passive Ozone Monitoring Instrument (OMI)). Strong smoke events are recognized as very difficult to quantify from space using passive (MODIS, OMI etc...) or active (CALIOP) satellite sensors for different reasons. This study is performed through (i) the selection of smoke events with coincident CALIOP and airborne HSRL aerosol observations, with smoke presence determined according to the HSRL aerosol classification data, (ii) the order of such events by range of HSRL aerosol optical depth, total color ratio and depolarization ratio (the latter two informing on the size and shape of the particles) and the evaluation of CALIOP's detection, classification and retrieval performance for each event, (iii) the study of the HSRL (or CALIOP when available) atmospheric parameters (total color ratio, volume depolarization ratio, mean attenuated backscatter) in the vicinity of clouds for each smoke event.

Kacenelenbogen, M. S.; Redemann, J.; Russell, P. B.; Vaughan, M.; Omar, A. H.; Burton, S. P.; Rogers, R.; Ferrare, R. A.; Hostetler, C. A.; Hair, J. W.

2011-12-01

154

Towards quantifying mesoscale flows in the troposphere using Raman lidar and Sondes  

NASA Technical Reports Server (NTRS)

Water vapor plays an important role in the energetics of the boundary layer processes which in turn play a key role in regulating regional and global climate. It plays a primary role in Earth's hydrological cycle, in radiation balance as a direct absorber of infrared radiation, and in atmospheric circulation as a latent heat energy source, as well as in determining cloud development and atmospheric stability. Water vapor concentration, expressed as a mass mixing ratio (g kg(exp -l)), is conserved in all meteorological processes except condensation and evaporation. This property makes it an ideal choice for studying many of the atmosphere's dynamic features. Raman scattering measurements from lidar also allow retrieval of water vapor mixing ratio profiles at high temporal and vertical resolution. Raman lidars sense water vapor to altitudes not achievable with towers and surface systems, sample the atmosphere at much higher temporal resolution than radiosondes or satellites, and do not require strong vertical gradients or turbulent fluctuations in temperature that is required by acoustic sounders and radars. Analysis of highly-resolved water vapor profiles are used here to characterize two important mesoscale flows: thunderstorm outflows and a cold front passage. The data were obtained at the Atmospheric Radiation Measurement Site (CART) by the groundbased Department of Energy/Sandia National Laboratories lidar (CART Raman lidar or CARL) and Goddard Space Flight Center Scanning Raman Lidar (SRL). A detailed discussion of the SRL and CARL performance during the IOPs is given by others in this meeting.

Demoz, B.; Starr, D.; Evans, K.; Whiteman, D.; Melfi, S.; Turner, D.; Ferrare, R.; Goldsmith, J.; Schwemmer, G.; Cadirola, M.

1998-01-01

155

Daytime operation of a pure rotational Raman lidar by use of a Fabry-Perot interferometer  

SciTech Connect

We propose to use a Fabry-Perot interferometer (FPI) in a pure rotational Raman lidar to isolate return signals that are due to pure rotational Raman scattering from atmospheric nitrogen against the sky background. The main idea of this instrumental approach is that a FPI is applied as a frequency comb filter with the transmission peaks accurately matched to a comb of practically equidistant lines of a pure rotational Raman spectrum (PRRS) of nitrogen molecules. Thus a matched FPI transmission comb cuts out the spectrally continuous sky background light from the spectral gaps between the PRRS lines of nitrogen molecules while it is transparent to light within narrow spectral intervals about these lines. As the width of the spectral gaps between the lines of the PRRS of nitrogen molecules is {approx}114 times the width of an individual spectral line, cutting out of the sky background from these gaps drastically improves the signal-to-background ratio of the pure rotational Raman lidar returns. This application of the FPI enables one to achieve daytime temperature profiling in the atmosphere with a pure rotational Raman lidar in the visible and near-UV spectral regions. We present an analysis of application of the FPI to filtering out the pure rotational Raman lidar returns against the solar background. To demonstrate the feasibility of the approach proposed, we present temperature profiles acquired during a whole-day measurement session in which a Raman lidar equipped with a FPI was used. For comparison, temperature profiles acquired with Vaisala radiosondes launched from the measurement site are also presented.

Arshinov, Yuri; Bobrovnikov, Sergey; Serikov, Ilya; Ansmann, Albert; Wandinger, Ulla; Althausen, Dietrich; Mattis, Ina; Mueller, Detlef

2005-06-10

156

Aerosol classification using airborne High Spectral Resolution Lidar measurements - methodology and examples  

NASA Astrophysics Data System (ADS)

The NASA Langley Research Center (LaRC) airborne High Spectral Resolution Lidar (HSRL) on the NASA B200 aircraft has acquired extensive datasets of aerosol extinction (532 nm), aerosol optical thickness (AOT) (532 nm), backscatter (532 and 1064 nm), and depolarization (532 and 1064 nm) profiles during 18 field missions that have been conducted over North America since 2006. The lidar measurements of aerosol intensive parameters (lidar ratio, depolarization, backscatter color ratio, and spectral depolarization ratio) are shown to vary with location and aerosol type. A methodology based on observations of known aerosol types is used to qualitatively classify the extensive set of HSRL aerosol measurements into eight separate types. Several examples are presented showing how the aerosol intensive parameters vary with aerosol type and how these aerosols are classified according to this new methodology. The HSRL-based classification reveals vertical variability of aerosol types during the NASA ARCTAS field experiment conducted over Alaska and northwest Canada during 2008. In two examples derived from flights conducted during ARCTAS, the HSRL classification of biomass burning smoke is shown to be consistent with aerosol types derived from coincident airborne in situ measurements of particle size and composition. The HSRL retrievals of AOT and inferences of aerosol types are used to apportion AOT to aerosol type; results of this analysis are shown for several experiments.

Burton, S. P.; Ferrare, R. A.; Hostetler, C. A.; Hair, J. W.; Rogers, R. R.; Obland, M. D.; Butler, C. F.; Cook, A. L.; Harper, D. B.; Froyd, K. D.

2011-09-01

157

Aerosol classification using airborne High Spectral Resolution Lidar measurements - methodology and examples  

NASA Astrophysics Data System (ADS)

The NASA Langley Research Center (LaRC) airborne High Spectral Resolution Lidar (HSRL) on the NASA B200 aircraft has acquired extensive datasets of aerosol extinction (532 nm), aerosol optical depth (AOD) (532 nm), backscatter (532 and 1064 nm), and depolarization (532 and 1064 nm) profiles during 18 field missions that have been conducted over North America since 2006. The lidar measurements of aerosol intensive parameters (lidar ratio, depolarization, backscatter color ratio, and spectral depolarization ratio) are shown to vary with location and aerosol type. A methodology based on observations of known aerosol types is used to qualitatively classify the extensive set of HSRL aerosol measurements into eight separate types. Several examples are presented showing how the aerosol intensive parameters vary with aerosol type and how these aerosols are classified according to this new methodology. The HSRL-based classification reveals vertical variability of aerosol types during the NASA ARCTAS field experiment conducted over Alaska and northwest Canada during 2008. In two examples derived from flights conducted during ARCTAS, the HSRL classification of biomass burning smoke is shown to be consistent with aerosol types derived from coincident airborne in situ measurements of particle size and composition. The HSRL retrievals of AOD and inferences of aerosol types are used to apportion AOD to aerosol type; results of this analysis are shown for several experiments.

Burton, S. P.; Ferrare, R. A.; Hostetler, C. A.; Hair, J. W.; Rogers, R. R.; Obland, M. D.; Butler, C. F.; Cook, A. L.; Harper, D. B.; Froyd, K. D.

2012-01-01

158

Forest fire smoke layers observed in the free troposphere over Portugal with a multiwavelength Raman lidar: optical and microphysical properties.  

PubMed

Vertically resolved optical and microphysical properties of biomass burning aerosols, measured in 2011 with a multiwavelength Raman lidar, are presented. The transportation time, within 1-2 days (or less), pointed towards the presence of relatively fresh smoke particles over the site. Some strong layers aloft were observed with particle backscatter and extinction coefficients (at 355 nm) greater than 5 Mm(-1)sr(-1) and close to 300 Mm(-1), respectively. The particle intensive optical properties showed features different from the ones reported for aged smoke, but rather consistent with fresh smoke. The Ångström exponents were generally high, mainly above 1.4, indicating a dominating accumulation mode. Weak depolarization values, as shown by the small depolarization ratio of 5% or lower, were measured. Furthermore, the lidar ratio presented no clear wavelength dependency. The inversion of the lidar signals provided a set of microphysical properties including particle effective radius below 0.2 ?m, which is less than values previously observed for aged smoke particles. Real and imaginary parts of refractive index of about 1.5-1.6 and 0.02i, respectively, were derived. The single scattering albedo was in the range between 0.85 and 0.93; these last two quantities indicate the nonnegligible absorbing characteristics of the observed particles. PMID:25114964

Nepomuceno Pereira, Sérgio; Preißler, Jana; Guerrero-Rascado, Juan Luis; Silva, Ana Maria; Wagner, Frank

2014-01-01

159

Aerosol optical and microphysical retrievals from a hybrid multiwavelength lidar data set - DISCOVER-AQ 2011  

NASA Astrophysics Data System (ADS)

Retrievals of aerosol microphysical properties (effective radius, volume and surface-area concentrations) and aerosol optical properties (complex index of refraction and single-scattering albedo) were obtained from a hybrid multiwavelength lidar data set for the first time. In July 2011, in the Baltimore-Washington DC region, synergistic profiling of optical and microphysical properties of aerosols with both airborne (in situ and remote sensing) and ground-based remote sensing systems was performed during the first deployment of DISCOVER-AQ. The hybrid multiwavelength lidar data set combines ground-based elastic backscatter lidar measurements at 355 nm with airborne High-Spectral-Resolution Lidar (HSRL) measurements at 532 nm and elastic backscatter lidar measurements at 1064 nm that were obtained less than 5 km apart from each other. This was the first study in which optical and microphysical retrievals from lidar were obtained during the day and directly compared to AERONET and in situ measurements for 11 cases. Good agreement was observed between lidar and AERONET retrievals. Larger discrepancies were observed between lidar retrievals and in situ measurements obtained by the aircraft and aerosol hygroscopic effects are believed to be the main factor in such discrepancies.

Sawamura, P.; Müller, D.; Hoff, R. M.; Hostetler, C. A.; Ferrare, R. A.; Hair, J. W.; Rogers, R. R.; Anderson, B. E.; Ziemba, L. D.; Beyersdorf, A. J.; Thornhill, K. L.; Winstead, E. L.; Holben, B. N.

2014-09-01

160

Comparison of modeled optical properties of Saharan mineral dust aerosols with SAMUM lidar and photometer observations  

NASA Astrophysics Data System (ADS)

Mineral dust aerosols are, for example, relevant for the radiative transfer in Earth's atmosphere. An important source of information on this aerosol type is provided by remote sensing using lidar systems and sun/sky photometers. We investigate the sensitivity of lidar and photometer observations to the microphysical aerosol properties in a numerical study. Knowledge of this sensitivity is required for the development of microphysical retrieval algorithms. Until recently, such retrieval algorithms were applied only to lidar or photometer observations. Quite different sensitivities for lidar and photometer are found in our study, suggesting that synergistic effects can be expected from combining the observations from both techniques. Furthermore, we compare the modeled aerosol properties to observations of Saharan mineral dust aerosols performed during the SAMUM field campaign. We determined aerosol ensembles that are consistent with the lidar as well as the photometer observations, confirming the feasibility of combining the observations from both techniques. The consistent aerosol ensembles are based on the desert mixture from the OPAC aerosol dataset, and were improved by considering mixing of absorbing and non-absorbing irregularly shaped particles.

Gasteiger, Josef; Wiegner, Matthias

2013-05-01

161

Retrieval of optical and microphysical properties of aerosols from a hybrid multiwavelength lidar dataset  

NASA Astrophysics Data System (ADS)

Over the past decade the development of inversion techniques for the retrievals of aerosol microphysical properties (e.g. effective radius, volume and surface-area concentrations) and aerosol optical properties (e.g. complex index of refraction and single scattering albedo) from multiwavelength lidar systems brought a new perspective in the study of the vertical distribution of aerosols. In this study retrievals of such parameters were obtained from a hybrid multiwavelength lidar dataset for the first time. In July of 2011, in the Baltimore-Washington DC region, synergistic profiling of optical and microphysical properties of aerosols with both airborne in-situ and ground-based remote sensing systems was performed during the first deployment of DISCOVER-AQ. The hybrid multiwavelength lidar dataset combines elastic ground-based measurements at 355 nm with airborne High Spectral Resolution Lidar (HSRL) measurements at 532 nm and elastic measurements at 1064 nm that were obtained less than 5 km apart of each other. This was the first study to our knowledge in which optical and microphysical retrievals from lidar were obtained during the day and directly compared to AERONET and in-situ measurements for eleven cases. Good agreement was observed between lidar and AERONET retrievals. Larger discrepancies were observed between lidar retrievals and in-situ measurements obtained by the aircraft and aerosol hygroscopic effects are believed to be the main factor of such discrepancies.

Sawamura, Patricia

162

High-spectral-resolution lidar measurements of aerosols, clouds, and temperature at NIES  

Microsoft Academic Search

A high spectral resolution lidar (HSRL) using a narrow-band frequency-doubled Nd:YAG laser and an iodine absorption filter has been developed and used for the observations of aerosols, clouds and temperature profiles at NIES, Tsukuba since December 1997. Examples of the measurements of the cloud and aerosol scattering parameters with this lidar are given in the paper. The results show that

Zhaoyan Liu; Ichiro Matsui; Nubuo Sugimoto

1998-01-01

163

Ultraviolet high-spectral-resolution Doppler lidar for measuring wind field and aerosol optical properties  

Microsoft Academic Search

An ultraviolet incoherent Doppler lidar that incorporates the high-spectral-resolution (HSR) technique has been developed for measuring the wind field and aerosol optical properties in the troposphere. An injection seeded and tripled Nd:YAG laser at an ultraviolet wavelength of 355 nm was used in the lidar system. The HRS technique can resolve the aerosol Mie backscatter and the molecular Rayleigh backscatter

Masaharu Imaki; Takao Kobayashi

2005-01-01

164

Algorithm to Retrieve Aerosol Optical Properties From High-Spectral-Resolution Lidar and Polarization Mie-Scattering Lidar Measurements  

Microsoft Academic Search

We developed an algorithm to estimate the vertical profiles of extinction coefficients at 532 nm for three aerosol types that are water-soluble, soot, and dust particles, using the extinction and backscattering coefficients at 532 nm for total aerosols derived from high-spectral-resolution lidar (HSRL) measurements and the receiving signal at 1064 nm and total depolarization ratio at 532 nm measured with

Tomoaki Nishizawa; Nobuo Sugimoto; Ichiro Matsui; Atsushi Shimizu; Boyan Tatarov; Hajime Okamoto

2008-01-01

165

Assessing the temperature dependence of narrow-band Raman water vapor lidar measurements: a practical approach.  

PubMed

Narrow-band detection of the Raman water vapor spectrum using the lidar technique introduces a concern over the temperature dependence of the Raman spectrum. Various groups have addressed this issue either by trying to minimize the temperature dependence to the point where it can be ignored or by correcting for whatever degree of temperature dependence exists. The traditional technique for performing either of these entails accurately measuring both the laser output wavelength and the water vapor spectral passband with combined uncertainty of approximately 0.01 nm. However, uncertainty in interference filter center wavelengths and laser output wavelengths can be this large or larger. These combined uncertainties translate into uncertainties in the magnitude of the temperature dependence of the Raman lidar water vapor measurement of 3% or more. We present here an alternate approach for accurately determining the temperature dependence of the Raman lidar water vapor measurement. This alternate approach entails acquiring sequential atmospheric profiles using the lidar while scanning the channel passband across portions of the Raman water vapor Q-branch. This scanning is accomplished either by tilt-tuning an interference filter or by scanning the output of a spectrometer. Through this process a peak in the transmitted intensity can be discerned in a manner that defines the spectral location of the channel passband with respect to the laser output wavelength to much higher accuracy than that achieved with standard laboratory techniques. Given the peak of the water vapor signal intensity curve, determined using the techniques described here, and an approximate knowledge of atmospheric temperature, the temperature dependence of a given Raman lidar profile can be determined with accuracy of 0.5% or better. A Mathematica notebook that demonstrates the calculations used here is available from the lead author. PMID:23913054

Whiteman, David N; Venable, Demetrius D; Walker, Monique; Cadirola, Martin; Sakai, Tetsu; Veselovskii, Igor

2013-08-01

166

Separating Dust Mixtures and Other External Aerosol Mixtures Using Airborne High Spectral Resolution Lidar Data  

NASA Astrophysics Data System (ADS)

Knowledge of aerosol type is important for source attribution and for determining the magnitude and assessing the consequences of aerosol radiative forcing. The NASA Langley Research Center airborne High Spectral Resolution Lidar (HSRL-1) has acquired considerable datasets of both aerosol extensive parameters (e.g. aerosol optical depth) and intensive parameters (e.g. aerosol depolarization ratio, lidar ratio) that can be used to infer aerosol type. An aerosol classification methodology has been used extensively to classify HSRL-1 aerosol measurements of different aerosol types including dust, smoke, urban pollution, and marine aerosol. However, atmospheric aerosol is frequently not a single pure type, but instead occurs as a mixture of types, and this mixing affects the optical and radiative properties of the aerosol. Here we present a comprehensive and unified set of rules for characterizing external mixtures using several key aerosol intensive parameters: extinction-to-backscatter ratio (i.e. lidar ratio), backscatter color ratio, and depolarization ratio. Our mixing rules apply not just to the scalar values of aerosol intensive parameters, but to multi-dimensional normal distributions with variance in each measurement dimension. We illustrate the applicability of the mixing rules using examples of HSRL-1 data where mixing occurred between different aerosol types, including advected Saharan dust mixed with the marine boundary layer in the Caribbean Sea and locally generated dust mixed with urban pollution in the Mexico City surroundings. For each of these cases we infer a time-height cross section of mixing ratio along the flight track and we partition aerosol extinction into portions attributed to the two pure types. Since multiple aerosol intensive parameters are measured and included in these calculations, the techniques can also be used for cases without significant depolarization (unlike similar work by earlier researchers), and so a third example of a mixture of smoke plus marine aerosol is also explored.

Burton, S. P.; Ferrare, R. A.; Vaughan, M.; Hostetler, C. A.; Rogers, R. R.; Hair, J. W.; Cook, A. L.; Harper, D. B.

2013-12-01

167

Vertically resolved separation of dust and smoke over Cape Verde using multiwavelength Raman and polarization lidars during Saharan Mineral Dust Experiment 2008  

NASA Astrophysics Data System (ADS)

Multiwavelength aerosol Raman lidar in combination with polarization lidar at Praia (14.9°N, 23.5°W), Cape Verde, is used to separate the optical properties of desert dust and biomass burning particles as a function of height in the mixed dust and smoke plumes over the tropical North Atlantic west of the African continent. The advanced lidar method furthermore permits the derivation of the single-scattering albedo and microphysical properties of the African biomass burning smoke. A case study is presented to discuss the potential of the technique. The observations were performed during the Saharan Mineral Dust Experiment (SAMUM) in January and February 2008. The height-resolved lidar results are compared with column-integrated products obtained with Aerosol Robotic Network Sun photometer. Good agreement is found. Furthermore, the findings are compared with lidar and aircraft observations recently performed in western Africa and with our previous lidar observations taken in tropical and subtropical regions of southern and eastern Asia. The SAMUM case study represents typical aerosol layering conditions in the tropical outflow regime of western Africa during winter season. Above a dense desert dust layer (with an optical depth of about 0.25 at 532 nm) which reached to 1500 m, a lofted layer consisting of desert dust (0.08 optical depth) and biomass burning smoke (0.24 optical depth) extended from 1500 to 5000 m height. Extinction values were 20 ± 10 Mm-1 (desert dust) and 20-80 Mm-1 (smoke) in the lofted plume. The smoke extinction-to-backscatter ratios were rather high, with values up to more than 100 sr, effective radii ranged from 0.15 to 0.35 ?m, and the smoke single-scattering albedo was partly below 0.7.

Tesche, M.; Ansmann, A.; Müller, D.; Althausen, D.; Engelmann, R.; Freudenthaler, V.; Groß, S.

2009-07-01

168

New algorithm to derive the microphysical properties of the aerosols from lidar measurements using OPAC aerosol classification schemes  

NASA Astrophysics Data System (ADS)

This paper presents a new method to retrieve the aerosol complex refractive index and effective radius from multiwavelength lidar data, using an integrated model-measurement approach. In the model, aerosols are assumed to be a non-spherical ensemble of internally mixed components, with variable proportions. OPAC classification schemes and basic components are used to calculate the microphysical properties, which are then fed into the T-matrix calculation code to generate the corresponding optical parameters. Aerosol intensive parameters (lidar ratios, extinction and backscatter Angstrom coefficients, and linear particle depolarization ratios) are computed at the altitude of the aerosol layers determined from lidar measurements, and iteratively compared to the values obtained by simulation for a certain aerosol type, for which the critical component's proportion in the overall mixture is varied. Microphysical inversion based on the Truncated Singular Value Decomposition (TSVD) algorithm is performed for selected cases of spherical aerosols, and comparative results of the two methods are shown. Keywords: Lidar, aerosols, Data inversion, Optical parameters, Complex Refractive Index Acknowledgments: This work has been supported by grants of the Romanian National Authority for Scientific Research, Programme for Research- Space Technology and Advanced Research - STAR, project numbers 38/2012 - CAPESA and 55/2013 - CARESSE, and by the European Community's FP7-INFRASTRUCTURES-2010-1 under grant no. 262254 - ACTRIS and by the European Community's FP7-PEOPLE-2011-ITN under grant no. 289923 - ITARS

Talianu, Camelia; Labzovskii, Lev; Toanca, Florica

2014-05-01

169

Lidar measurements of the post-fuego stratospheric aerosol  

NASA Technical Reports Server (NTRS)

Fifteen lidar observations of the stratospheric aerosol were made between February and November 1975. All observations revealed the greatly increased particulate backscattering that followed the eruption of the volcano Fuego in October 1974. Vertical structure consisted initially of multiple layers, which later merged to form a single, broader peak. Essentially all of the increased scattering was confined to altitudes below 20 km. Hence, aerosol layer centroids in 1975 were typically several km below their altitude prior to the eruption. Radiative and thermal consequences of the measured post-Fuego layer were computed using several recently published models. The models predict a temperature increase of several K at the altitude of the layer, caused by the infrared absorption bands of the sulfuric acid particles. The surface temperature decrease predicted by the models is considerably smaller than 1 K, partly because of the small optical thickness of the volcanic layer, and partly because of its short residence time relative to the earth-ocean thermal response time.

Russell, P. B.; Hake, R. D., Jr.; Viezee, W.

1976-01-01

170

The Cloud-Aerosol Transport System (CATS): a new lidar for aerosol and cloud profiling from the International Space Station  

NASA Astrophysics Data System (ADS)

Spaceborne lidar profiling of aerosol and cloud layers has been successfully implemented during a number of prior missions, including LITE, ICESat, and CALIPSO. Each successive mission has added increased capability and further expanded the role of these unique measurements in wide variety of applications ranging from climate, to air quality, to special event monitoring (ie, volcanic plumes). Many researchers have come to rely on the availability of profile data from CALIPSO, especially data coincident with measurements from other A-Train sensors. The CALIOP lidar on CALIPSO continues to operate well as it enters its fifth year of operations. However, active instruments have more limited lifetimes than their passive counterparts, and we are faced with a potential gap in lidar profiling from space if the CALIOP lidar fails before a new mission is operational. The ATLID lidar on EarthCARE is not expected to launch until 2015 or later, and the lidar component of NASA's proposed Aerosols, Clouds, and Ecosystems (ACE) mission would not be until after 2020. Here we present a new aerosol and cloud lidar that was recently selected to provide profiling data from the International Space Station (ISS) starting in 2013. The Cloud-Aerosol Transport System (CATS) is a three wavelength (1064, 532, 355 nm) elastic backscatter lidar with HSRL capability at 532 nm. Depolarization measurements will be made at all wavelengths. The primary objective of CATS is to continue the CALIPSO aerosol and cloud profile data record, ideally with overlap between both missions and EarthCARE. In addition, the near real time data capability of the ISS will enable CATS to support operational applications such as air quality and special event monitoring. The HSRL channel will provide a demonstration of technology and a data testbed for direct extinction retrievals in support of ACE mission development. An overview of the instrument and mission will be provided, along with a summary of the science objectives and simulated data.

Welton, E. J.; McGill, M. J.; Yorks, J. E.; Hlavka, D. L.; Hart, W. D.; Palm, S. P.; Colarco, P. R.

2011-12-01

171

The Cloud-Aerosol Transport System (CATS): a New Lidar for Aerosol and Cloud Profiling from the International Space Station  

NASA Technical Reports Server (NTRS)

Spaceborne lidar profiling of aerosol and cloud layers has been successfully implemented during a number of prior missions, including LITE, ICESat, and CALIPSO. Each successive mission has added increased capability and further expanded the role of these unique measurements in wide variety of applications ranging from climate, to air quality, to special event monitoring (ie, volcanic plumes). Many researchers have come to rely on the availability of profile data from CALIPSO, especially data coincident with measurements from other A-Train sensors. The CALIOP lidar on CALIPSO continues to operate well as it enters its fifth year of operations. However, active instruments have more limited lifetimes than their passive counterparts, and we are faced with a potential gap in lidar profiling from space if the CALIOP lidar fails before a new mission is operational. The ATLID lidar on EarthCARE is not expected to launch until 2015 or later, and the lidar component of NASA's proposed Aerosols, Clouds, and Ecosystems (ACE) mission would not be until after 2020. Here we present a new aerosol and cloud lidar that was recently selected to provide profiling data from the International Space Station (ISS) starting in 2013. The Cloud-Aerosol Transport System (CATS) is a three wavelength (1064, 532, 355 nm) elastic backscatter lidar with HSRL capability at 532 nm. Depolarization measurements will be made at all wavelengths. The primary objective of CATS is to continue the CALIPSO aerosol and cloud profile data record, ideally with overlap between both missions and EarthCARE. In addition, the near real time data capability of the ISS will enable CATS to support operational applications such as air quality and special event monitoring. The HSRL channel will provide a demonstration of technology and a data testbed for direct extinction retrievals in support of ACE mission development. An overview of the instrument and mission will be provided, along with a summary of the science objectives and simulated data.

Welton, Ellsworth J.; McGill, Matthew J.; Yorks, John E.; Hlavka, Dennis L.; Hart, William D.; Palm, Stephen P.; Colarco, Peter R.

2011-01-01

172

Atmospheric lidar research applying to H2O, O2 and aerosols  

NASA Technical Reports Server (NTRS)

Experimental research on a near infrared tunable dye laser was reported, and theoretical simulations were presented for various lidar configurations. The visible and nearinfrared wavelengths considered were suitable for observations of aerosols, water vapor, molecular oxygen pressure and temperature in the troposphere and above. The first phase of development work was described on a ruby pumped, tunable dye laser for the wavelength region 715 to 740 nanometers. Lidar simulations were summarized for measurements of H2O and for two color lidar observations of aerosols in the atmosphere.

Mcilrath, T. J.; Wilkerson, T. D.

1977-01-01

173

Effect of aerosol particle microstructure on cw Doppler lidar signal statistics.  

PubMed

Analysis of signal statistical characteristics is carried out, and estimation errors of the radial wind velocity are calculated by use of numerical simulation of a cw Doppler lidar return, taking into account the atmospheric aerosol microstructure. It has been found that, at small sounded volume, the large particles contribute significantly to the scattered field. As a result the lidar return probability density function distribution can differ significantly from a Gaussian distribution. Neglect of the aerosol microstructure effect results in considerable underestimation of the error of cw Doppler lidar velocity estimates at small sounded volume. PMID:18354536

Banakh, V A; Smalikho, I N; Werner, C

2000-10-20

174

Ultraviolet high-spectral-resolution Doppler lidar for measuring wind field and aerosol optical properties  

SciTech Connect

An ultraviolet incoherent Doppler lidar that incorporates the high-spectral-resolution (HSR) technique has been developed for measuring the wind field and aerosol optical properties in the troposphere. An injection seeded and tripled Nd:YAG laser at an ultraviolet wavelength of 355 nm was used in the lidar system. The HRS technique can resolve the aerosol Mie backscatter and the molecular Rayleigh backscatter to derive the signal components. By detecting the Mie backscatter, a great increase in the Doppler filter sensitivity was realized compared to the conventional incoherent Doppler lidars that detected the Rayleigh backscatter. The wind velocity distribution in a two-dimensional cross section was measured. By using the HSR technique, multifunction and absolute value measurements were realized for aerosol extinction, and volume backscatter coefficients; the laser beam transmittance, the lidar ratio, and the backscatter ratio are derived from these measurements.

Imaki, Masaharu; Kobayashi, Takao

2005-10-01

175

Ultraviolet high-spectral-resolution Doppler lidar for measuring wind field and aerosol optical properties.  

PubMed

An ultraviolet incoherent Doppler lidar that incorporates the high-spectral-resolution (HSR) technique has been developed for measuring the wind field and aerosol optical properties in the troposphere. An injection seeded and tripled Nd:YAG laser at an ultraviolet wavelength of 355 nm was used in the lidar system. The HRS technique can resolve the aerosol Mie backscatter and the molecular Rayleigh backscatter to derive the signal components. By detecting the Mie backscatter, a great increase in the Doppler filter sensitivity was realized compared to the conventional incoherent Doppler lidars that detected the Rayleigh backscatter. The wind velocity distribution in a two-dimensional cross section was measured. By using the HSR technique, multifunction and absolute value measurements were realized for aerosol extinction, and volume backscatter coefficients; the laser beam transmittance, the lidar ratio, and the backscatter ratio are derived from these measurements. PMID:16231810

Imaki, Masaharu; Kobayashi, Takao

2005-10-01

176

An Aerosol Extinction-to-Backscatter Ratio Database Derived from the NASA Micro-Pulse Lidar Network: Applications for Space-based Lidar Observations  

NASA Technical Reports Server (NTRS)

Backscatter lidar signals are a function of both backscatter and extinction. Hence, these lidar observations alone cannot separate the two quantities. The aerosol extinction-to-backscatter ratio, S, is the key parameter required to accurately retrieve extinction and optical depth from backscatter lidar observations of aerosol layers. S is commonly defined as 4*pi divided by the product of the single scatter albedo and the phase function at 180-degree scattering angle. Values of S for different aerosol types are not well known, and are even more difficult to determine when aerosols become mixed. Here we present a new lidar-sunphotometer S database derived from Observations of the NASA Micro-Pulse Lidar Network (MPLNET). MPLNET is a growing worldwide network of eye-safe backscatter lidars co-located with sunphotometers in the NASA Aerosol Robotic Network (AERONET). Values of S for different aerosol species and geographic regions will be presented. A framework for constructing an S look-up table will be shown. Look-up tables of S are needed to calculate aerosol extinction and optical depth from space-based lidar observations in the absence of co-located AOD data. Applications for using the new S look-up table to reprocess aerosol products from NASA's Geoscience Laser Altimeter System (GLAS) will be discussed.

Welton, Ellsworth J.; Campbell, James R.; Spinhime, James D.; Berkoff, Timothy A.; Holben, Brent; Tsay, Si-Chee; Bucholtz, Anthony

2004-01-01

177

On the Feasibility of Studying Shortwave Aerosol Radiative Forcing of Climate Using Dual-Wavelength Aerosol Backscatter Lidar  

NASA Technical Reports Server (NTRS)

The current low confidence in the estimates of aerosol-induced perturbations of Earth's radiation balance is caused by the highly non-uniform compositional, spatial and temporal distributions of tropospheric aerosols on a global scale owing to their heterogeneous sources and short lifetimes. Nevertheless, recent studies have shown that the inclusion of aerosol effects in climate model calculations can improve agreement with observed spatial and temporal temperature distributions. In light of the short lifetimes of aerosols, determination of their global distribution with space-borne sensors seems to be a necessary approach. Until recently, satellite measurements of tropospheric aerosols have been approximate and did not provide the full set of information required to determine their radiative effects. With the advent of active aerosol remote sensing from space (e.g., PICASSO-CENA), the applicability fo lidar-derived aerosol 180 deg -backscatter data to radiative flux calculations and hence studies of aerosol effects on climate needs to be investigated.

Redemann, Jens; Russell, Philip B.; Winker, David M.; McCormick, M. Patrick; Hipskind, R. Stephen (Technical Monitor)

2000-01-01

178

Lidar observations of atmospheric aerosols following the 1980 eruption of Mt. St. Helens. I  

Microsoft Academic Search

A significant increase and subsequent variations of stratospheric aerosols caused by the eruption of Mt. St. Helens on May 18, 1980 have been observed using YAG lidar at a wavelength of 1.06 microns for a period of one year at Fukuoka, Japan. The time variation of aerosols is compared with numerical results of two-dimensional model calculations, which show longer decay

M. Hirono; M. Fujiwara; T. Shibata; N. Kugumiya

1984-01-01

179

Aerosol optical properties retrieved from airborne high spectral resolution lidar during EUCAARI  

Microsoft Academic Search

As part of EUCAARI (European integrated project on Aerosol Cloud Climate and Air Quality Interactions) the field campaign LONGREX (LONG Range Experiment) was carried out in May \\/ June 2008 to investigate physical and chemical properties of aerosols on European scale. During the campaign the DLR Falcon research aircraft was equipped with a nadir-looking high spectral resolution lidar (HSRL) and

M. Esselborn; F. Abicht; M. Wirth; A. Fix; G. Ehret

2009-01-01

180

Methods of Analysis of Atmospheric Aerosols from Future Spaceborne High Spectral Resolution Lidar Data  

Microsoft Academic Search

The limitations of single wavelength elastic scatter lidar with regard to retrieving various optical or microphysical properties of the observed aerosols are well known. Typical retrieval methodologies rely on elastic scatter information at at least two wavelengths, together with either temporally or geographically inferred estimates of the extinction-to-back-scatter ratio Sa, or aerosol model parameters which constrain the solution in such

Christopher J. McPherson; John A. Reagan; Richard A. Ferrare; Chris A. Hostetler; Johnathan Hair

2009-01-01

181

AIRBORNE HIGH SPECTRAL RESOLUTION LIDAR AEROSOL MEASUREMENTS AND COMPARISONS WITH TRANSPORT MODELS  

E-print Network

Resolution Lidar (HSRL) measured aerosol distributions and optical properties during several field Satellite Observation (CALIPSO) and Twilight Zone (CATZ) experiment. The LaRC airborne HSRL uses and extinction profiles at 1064 nm. Aerosol depolarization profiles are measured at both wavelengths. The HSRL

182

Remote measurements of tropospheric aerosol scattering properties by an airborne high spectral resolution lidar  

Microsoft Academic Search

The High Spectral Resolution Lidar (HSRL) measures optical properties of atmospheric aerosols by interferometrically separating the elastic aerosol backscatter from the Doppler broadened molecular signal. HSRL flight evaluation tests were conducted during the summer of 1980. Data acquired during flight evaluations were obtained under both day and night background lighting conditions with an average laser output of 2 mw. The

J. T. Sroga

1983-01-01

183

A Compact Airborne High Spectral Resolution Lidar for Observations of Aerosol and Cloud Optical Properties  

Microsoft Academic Search

We are in the process of developing a nadir-viewing, aircraft-based high spectral resolution lidar (HSRL) at NASA Langley Research Center. The system is designed to measure backscatter and extinction of aerosols and tenuous clouds. The primary uses of the instrument will be to validate spaceborne aerosol and cloud observations, carry out regional process studies, and assess the predictions of chemical

Chris A. Hostetler; John W. Hair; Anthony L. Cook

184

The CALIPSO mission: Spaceborne lidar for observation of aerosols and clouds  

Microsoft Academic Search

Current uncertainties in the effects of aerosols and clouds on the Earth radiation budget limit our understanding of the climate system and the potential for global climate change. The CALIPSO satellite will use an active lidar together with passive instruments to provide vertical profiles of aerosols and clouds and their properties which w ill help address these uncertainties. CALIPSO will

David M. Winker; Jacques Pelon; M Patrick McCormick

185

Separating mixtures of aerosol types in airborne High Spectral Resolution Lidar data  

NASA Astrophysics Data System (ADS)

Knowledge of aerosol type is important for determining the magnitude and assessing the consequences of aerosol radiative forcing, and can provide useful information for source attribution studies. However, atmospheric aerosol is frequently not a single pure type, but instead occurs as a mixture of types, and this mixing affects the optical and radiative properties of the aerosol. This paper extends the work of earlier researchers by using the aerosol intensive parameters measured by the NASA Langley Research Center airborne High Spectral Resolution Lidar (HSRL-1) to develop a comprehensive and unified set of rules for characterizing the external mixing of several key aerosol intensive parameters: extinction-to-backscatter ratio (i.e., lidar ratio), backscatter color ratio, and depolarization ratio. We present the mixing rules in a particularly simple form that leads easily to mixing rules for the covariance matrices that describe aerosol distributions, rather than just single values of measured parameters. These rules can be applied to infer mixing ratios from the lidar-observed aerosol parameters, even for cases without significant depolarization. We demonstrate our technique with measurement curtains from three HSRL-1 flights which exhibit mixing between two aerosol types, urban pollution plus dust, marine plus dust, and smoke plus marine. For these cases, we infer a time-height cross-section of extinction mixing ratio along the flight track, and partition aerosol extinction into portions attributed to the two pure types.

Burton, S. P.; Vaughan, M. A.; Ferrare, R. A.; Hostetler, C. A.

2014-02-01

186

Separating mixtures of aerosol types in airborne High Spectral Resolution Lidar data  

NASA Astrophysics Data System (ADS)

Knowledge of aerosol type is important for source attribution and for determining the magnitude and assessing the consequences of aerosol radiative forcing. However, atmospheric aerosol is frequently not a single pure type, but instead occurs as a mixture of types, and this mixing affects the optical and radiative properties of the aerosol. This paper extends the work of earlier researchers by using the aerosol intensive parameters measured by the NASA Langley Research Center airborne High Spectral Resolution Lidar (HSRL-1) to develop a comprehensive and unified set of rules for characterizing the external mixing of several key aerosol intensive parameters: extinction-to-backscatter ratio (i.e. lidar ratio), backscatter color ratio, and depolarization ratio. We present the mixing rules in a particularly simple form that leads easily to mixing rules for the covariance matrices that describe aerosol distributions, rather than just scalar values of measured parameters. These rules can be applied to infer mixing ratios from the lidar-observed aerosol parameters, even for cases without significant depolarization. We demonstrate our technique with measurement curtains from three HSRL-1 flights which exhibit mixing between two aerosol types, urban pollution plus dust, marine plus dust, and smoke plus marine. For these cases, we infer a time-height cross-section of mixing ratio along the flight track, and partition aerosol extinction into portions attributed to the two pure types.

Burton, S. P.; Vaughan, M. A.; Ferrare, R. A.; Hostetler, C. A.

2013-09-01

187

Retrieval and analysis of a polarized high-spectral-resolution lidar for profiling aerosol optical properties.  

PubMed

Taking advantage of the broad spectrum of the Cabannes-Brillouin scatter from atmospheric molecules, the high spectral resolution lidar (HSRL) technique employs a narrow spectral filter to separate the aerosol and molecular scattering components in the lidar return signals and therefore can obtain the aerosol optical properties as well as the lidar ratio (i.e., the extinction-to-backscatter ratio) which is normally selected or modeled in traditional backscatter lidars. A polarized HSRL instrument, which employs an interferometric spectral filter, is under development at the Zhejiang University (ZJU), China. In this paper, the theoretical basis to retrieve the aerosol lidar ratio, depolarization ratio and extinction and backscatter coefficients, is presented. Error analyses and sensitivity studies have been carried out on the spectral transmittance characteristics of the spectral filter. The result shows that a filter that has as small aerosol transmittance (i.e., large aerosol rejection rate) and large molecular transmittance as possible is desirable. To achieve accurate retrieval, the transmittance of the spectral filter for molecular and aerosol scattering signals should be well characterized. PMID:23736562

Liu, Dong; Yang, Yongying; Cheng, Zhongtao; Huang, Hanlu; Zhang, Bo; Ling, Tong; Shen, Yibing

2013-06-01

188

Selection Algorithm for the CALIPSO Lidar Aerosol Extinction-to-Backscatter Ratio  

NASA Technical Reports Server (NTRS)

The extinction-to-backscatter ratio (S(sub a)) is an important parameter used in the determination of the aerosol extinction and subsequently the optical depth from lidar backscatter measurements. We outline the algorithm used to determine Sa for the Cloud and Aerosol Lidar and Infrared Pathfinder Spaceborne Observations (CALIPSO) lidar. S(sub a) for the CALIPSO lidar will either be selected from a look-up table or calculated using the lidar measurements depending on the characteristics of aerosol layer. Whenever suitable lofted layers are encountered, S(sub a) is computed directly from the integrated backscatter and transmittance. In all other cases, the CALIPSO observables: the depolarization ratio, delta, the layer integrated attenuated backscatter, beta, and the mean layer total attenuated color ratio, gamma, together with the surface type, are used to aid in aerosol typing. Once the type is identified, a look-up-table developed primarily from worldwide observations, is used to determine the S(sub a) value. The CALIPSO aerosol models include desert dust, biomass burning, background, polluted continental, polluted dust, and marine aerosols.

Omar, Ali H.; Winker, David M.; Vaughan, Mark A.

2006-01-01

189

Aerosol Profile Measurements from the NASA Langley Research Center Airborne High Spectral Resolution Lidar  

NASA Technical Reports Server (NTRS)

Since achieving first light in December of 2005, the NASA Langley Research Center (LaRC) Airborne High Spectral Resolution Lidar (HSRL) has been involved in seven field campaigns, accumulating over 450 hours of science data across more than 120 flights. Data from the instrument have been used in a variety of studies including validation and comparison with the Cloud- Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite mission, aerosol property retrievals combining passive and active instrument measurements, aerosol type identification, aerosol-cloud interactions, and cloud top and planetary boundary layer (PBL) height determinations. Measurements and lessons learned from the HSRL are leading towards next-generation HSRL instrument designs that will enable even further studies of aerosol intensive and extensive parameters and the effects of aerosols on the climate system. This paper will highlight several of the areas in which the NASA Airborne HSRL is making contributions to climate science.

Obland, Michael D.; Hostetler, Chris A.; Ferrare, Richard A.; Hair, John W.; Roers, Raymond R.; Burton, Sharon P.; Cook, Anthony L.; Harper, David B.

2008-01-01

190

Variation in daytime troposphereic aerosol via LIDAR and sunphotometer measurements in Penang, Malaysia  

NASA Astrophysics Data System (ADS)

Aerosol is one of the important factors that will influence the air quality, visibility, clouds, and precipitation processes in the troposphere. In this work, we investigated the variation of aerosol during daytime in Penang, Malaysia in certain days within July 2013. Vertical LIDAR scattering ratio and backscattering profiles, and columnar optical properties (optical depth, Angström exponent) of aerosols were measured using Raymetrics LIDAR and a CIMEL sunphotometer respectively. Specifically, we have determined the daytime variation of intensity and distribution level of aerosol, as well as the planetary boundary layer (PBL) and cloud classification. Subsequently, the data of columnar aerosol optical depth (AOD) and size distribution in the atmospheric were used to quantify the properties of aerosol variation during daytime over Penang, Malaysia.

Tan, F. Y.; Hee, W. S.; Hwee, S. L.; Abdullah, K.; Tiem, L. Y.; Matjafri, M. Z.; Lolli, S.; Holben, B.; Welton, E. J.

2014-03-01

191

Lidar Measurements of Stratospheric Ozone, Temperature and Aerosol During 1992 UARS Correlative Measurement Campaign  

NASA Technical Reports Server (NTRS)

Measurements of stratospheric ozone, temperature, and aerosols were made by the NASA/GSFC mobile stratospheric lidar during the UARS (Upper Atmospheric Research Satellite) Correlative Measurement Campaign at the JPL-Table Mountain Facility in Feb. and Mar. 1992. Due to the presence of substantial amounts of residual volcanic aerosol from the eruption of Mt. Pinatubo, the GSFC lidar system was modified for an accurate measurement of ozone concentration in the stratosphere. While designed primarily for the measurement of stratospheric ozone, this lidar system was also used to measure middle atmosphere temperature and density from 30 to 65 km and stratospheric aerosol from 15 to 35 km. In the following sections, we will briefly describe and present some typical measurements made during this campaign. Stratospheric ozone, temperature, and aerosols profiles derived from data taken between 15 Feb. and 20 Mar., 1992 will be presented at the conference.

Mcgee, Thomas J.; Singh, Upendra N.; Gross, Michael; Heaps, William S.; Ferrare, Richard

1992-01-01

192

Plume detection and tracking using Doppler lidar aerosol and wind data  

Microsoft Academic Search

Doppler lidar sensors provide a unique capability to generate high resolution 3D distributions of wind and aerosol data. Appropriately processed, these data can yield useful detection, tracking and short-term prediction information relating to the extent, density and location of potentially dangerous isolated aerosol plumes. The aerosol data are analyzed to detect above-threshold inhomogeneities and the wind and turbulence data are

Stephen M. Hannon; J. Alex L. Thomson; Duane D. Smith

1999-01-01

193

Simulations of the observation of clouds and aerosols with the Experimental Lidar in Space Equipment system.  

PubMed

We carried out a simulation study for the observation of clouds and aerosols with the Japanese Experimental Lidar in Space Equipment (ELISE), which is a two-wavelength backscatter lidar with three detection channels. The National Space Development Agency of Japan plans to launch the ELISE on the Mission Demonstrate Satellite 2 (MDS-2). In the simulations, the lidar return signals for the ELISE are calculated for an artificial, two-dimensional atmospheric model including different types of clouds and aerosols. The signal detection processes are simulated realistically by inclusion of various sources of noise. The lidar signals that are generated are then used as input for simulations of data analysis with inversion algorithms to investigate retrieval of the optical properties of clouds and aerosols. The results demonstrate that the ELISE can provide global data on the structures and optical properties of clouds and aerosols. We also conducted an analysis of the effects of cloud inhomogeneity on retrievals from averaged lidar profiles. We show that the effects are significant for space lidar observations of optically thick broken clouds. PMID:18345243

Liu, Z; Voelger, P; Sugimoto, N

2000-06-20

194

Aerosol optical and microphysical retrievals from a hybrid multiwavelength lidar dataset - DISCOVER-AQ 2011  

NASA Astrophysics Data System (ADS)

Retrievals of aerosol microphysical properties (e.g. effective radius, volume and surface-area concentrations) and aerosol optical properties (e.g. complex index of refraction and single scattering albedo) were obtained from a hybrid multiwavelength lidar dataset for the first time. In July of 2011, in the Baltimore-Washington DC region, synergistic profiling of optical and microphysical properties of aerosols with both airborne in-situ and ground-based remote sensing systems was performed during the first deployment of DISCOVER-AQ. The hybrid multiwavelength lidar dataset combines elastic ground-based measurements at 355 nm with airborne High Spectral Resolution Lidar (HSRL) measurements at 532 nm and elastic measurements at 1064 nm that were obtained less than 5 km apart of each other. This was the first study in which optical and microphysical retrievals from lidar were obtained during the day and directly compared to AERONET and in-situ measurements for 11 cases. Good agreement was observed between lidar and AERONET retrievals. Larger discrepancies were observed between lidar retrievals and in-situ measurements obtained by the aircraft and aerosol hygroscopic effects are believed to be the main factor of such discrepancies.

Sawamura, P.; Müller, D.; Hoff, R. M.; Hostetler, C. A.; Ferrare, R. A.; Hair, J. W.; Rogers, R. R.; Anderson, B. E.; Ziemba, L. D.; Beyersdorf, A. J.; Thornhill, K. L.; Winstead, E. L.; Holben, B. N.

2014-03-01

195

Direct-detection Doppler wind measurements with a CabannesMie lidar: B. Impact of aerosol variation on  

E-print Network

Direct-detection Doppler wind measurements with a Cabannes­Mie lidar: B. Impact of aerosol-of-sight (LOS) wind measurement by means of incoherent Cabannes­ Mie lidar with three frequency analyzers, two for operating the wind lidar at visible wavelengths under sunlit condition is discussed; with such a filter

196

Independent measurement of extinction and backscatter profiles in cirrus clouds by using a combined Raman elastic-backscatter lidar  

Microsoft Academic Search

Height profiles of the extinction and the backscatter coefficients in cirrus clouds are determined independently from elastic- and inelastic- (Raman) backscatter signals. An extended error analysis is given. Examples covering the measured range of extinction-to-backscatter ratios (lidar ratios) in ice clouds are presented. Lidar ratios between 5 and 15 sr are usually found. A strong variation between 2 and 20

Albert Ansmann; Ulla Wandinger; Maren Riebesell; Claus Weitkamp; Walfried Michaelis

1992-01-01

197

Progress in the validation of dual-wavelength aerosol retrieval models via airborne high spectral resolution lidar data  

Microsoft Academic Search

The Constrained Ratio Aerosol Model-fit (CRAM) technique is a method for making aerosol retrievals from dual-wavelength elastic scatter lidars which attempts to constrain the retrievals so as to be consistent with a number of aerosol models thought to characterize a variety of aerosol types observed around the world. The NASA Langley Research Center Airborne HSRL is an airborne high spectral

Christopher McPherson; John A. Reagan; Chris Hostetler; Johnathan Hair; Richard Ferrare

2010-01-01

198

Micropulse lidar observations of tropospheric aerosols over northeastern South Africa during the ARREX and SAFARI 2000 dry season experiments  

Microsoft Academic Search

During the Aerosol Recirculation and Rainfall Experiment (ARREX 1999) and Southern African Regional Science Initiative (SAFARI 2000) dry season experiments, a micropulse lidar (523 nm) instrument was operated at the Skukuza Airport in northeastern South Africa. The lidar was colocated with a diverse array of passive radiometric equipment. For SAFARI 2000, a daytime time series of layer mean aerosol optical

James R. Campbell; Ellsworth J. Welton; James D. Spinhirne; Qiang Ji; Si-Chee Tsay; Stuart J. Piketh; Marguerite Barenbrug; Brent N. Holben

2003-01-01

199

Influence of molecular scattering models on aerosol optical properties measured by high spectral resolution lidar.  

PubMed

The influence of molecular scattering models on aerosol optical properties measured by high spectral resolution lidar (HSRL) is experimentally investigated and theoretically evaluated. The measurements analyzed in this study were made during three field campaigns by the German Aerospace Center airborne HSRL. The influence of the respective theoretical model on spaceborne HSRL retrievals is also estimated. Generally, the influence on aerosol extinction coefficient can be neglected for both airborne and spaceborne HSRLs. However, the influence on aerosol backscatter coefficient depends on aerosol concentration and is larger than 3% (6%) at ground level for airborne (spaceborne) HSRLs, which is considerable for the spaceborne HSRL, especially when the aerosol concentration is low. A comparison of the HSRL measurements and coordinated ground-based sunphotometer measurements shows that the influence of the model is observable and comparable to the measurement error of the lidar system. PMID:19767932

Liu, Bing-Yi; Esselborn, Michael; Wirth, Martin; Fix, Andreas; Bi, De-Cang; Ehret, Gerhard

2009-09-20

200

Comparison of Summer and Winter California Central Valley Aerosol Distributions from Lidar and MODIS Measurements  

NASA Technical Reports Server (NTRS)

Aerosol distributions from two aircraft lidar campaigns conducted in the California Central Valley are compared in order to identify seasonal variations. Aircraft lidar flights were conducted in June 2003 and February 2008. While the PM2.5 concentration is highest in the winter, the aerosol optical depth measured from MODIS is highest in the summer. A seasonal comparison shows that PM2.5 in the winter can exceed summer PM2.5 by 55%, while summer AOD exceeds winter AOD by 43%. Higher temperatures wildfires in the summer produce elevated aerosol layers that are detected by satellite measurements, but not surface particulate matter monitors. Measurements of the boundary layer height from lidar instruments are necessary to incorporate satellite measurements with air quality measurements.

Lewis, Jasper R., Jr.; DeYoung, Russell J.; Chu, D. Allen

2010-01-01

201

The Cloud-Aerosol Transport System (CATS): a new lidar for aerosol and cloud profiling from the International Space Station  

NASA Astrophysics Data System (ADS)

Spaceborne lidar profiling of aerosol and cloud layers has been successfully implemented during a number of prior missions, including LITE, ICESat, and CALIPSO. Each successive mission has added increased capability and further expanded the role of these unique measurements in wide variety of applications ranging from climate, to air quality, to special event monitoring (ie, volcanic plumes). Many researchers have come to rely on the availability of profile data from CALIPSO, especially data coincident with measurements from other A-Train sensors. The CALIOP lidar on CALIPSO continues to operate well as it enters its fifth year of operations. However, active instruments have more limited lifetimes than their passive counterparts, and we are faced with a potential gap in lidar profiling from space if the CALIOP lidar fails before a new mission is operational. The ATLID lidar on EarthCARE is not expected to launch until 2015 or later, and the lidar component of NASA's proposed Aerosols, Clouds, and Ecosystems (ACE) mission would not be until after 2020. Here we present a new aerosol and cloud lidar that was recently selected to provide profiling data from the International Space Station (ISS) starting in 2013. The Cloud-Aerosol Transport System (CATS) is a three wavelength (1064, 532, 355 nm) elastic backscatter lidar with HSRL capability at 532 nm. Depolarization measurements will be made at all wavelengths. The primary objective of CATS is to continue the CALIPSO aerosol and cloud profile data record, ideally with overlap between both missions and EarthCARE. In addition, the near real time (NRT) data capability of the ISS will enable CATS to support operational applications such as aerosol and air quality forecasting and special event monitoring. The HSRL channel will provide a demonstration of technology and a data testbed for direct extinction retrievals in support of ACE mission development. An overview of the instrument and mission will be provided, along with a summary of the science objectives and simulated data. Results from the NASA Goddard Earth Observing System general circulation model and data assimilation system (GEOS-5) have been used to generate the simulated data, and will be used to help process CATS data after launch.

Welton, E. J.; McGill, M. J.; Yorks, J. E.; Hlavka, D. L.; Hart, W. D.; Palm, S. P.; Colarco, P. R.

2012-12-01

202

The Cloud-Aerosol Transport System (CATS): A New Lidar for Aerosol and Cloud Profiling from the International Space Station  

NASA Technical Reports Server (NTRS)

Spaceborne lidar profiling of aerosol and cloud layers has been successfully implemented during a number of prior missions, including LITE, ICESat, and CALIPSO. Each successive mission has added increased capability and further expanded the role of these unique measurements in wide variety of applications ranging from climate, to air quality, to special event monitoring (ie, volcanic plumes). Many researchers have come to rely on the availability of profile data from CALIPSO, especially data coincident with measurements from other A-Train sensors. The CALIOP lidar on CALIPSO continues to operate well as it enters its fifth year of operations. However, active instruments have more limited lifetimes than their passive counterparts, and we are faced with a potential gap in lidar profiling from space if the CALIOP lidar fails before a new mission is operational. The ATLID lidar on EarthCARE is not expected to launch until 2015 or later, and the lidar component of NASA's proposed Aerosols, Clouds, and Ecosystems (ACE) mission would not be until after 2020. Here we present a new aerosol and cloud lidar that was recently selected to provide profiling data from the International Space Station (ISS) starting in 2013. The Cloud-Aerosol Transport System (CATS) is a three wavelength (1064,532,355 nm) elastic backscatter lidar with HSRL capability at 532 nm. Depolarization measurements will be made at all wavelengths. The primary objective of CATS is to continue the CALIPSO aerosol and cloud profile data record, ideally with overlap between both missions and EarthCARE. In addition, the near real time (NRT) data capability ofthe ISS will enable CATS to support operational applications such as aerosol and air quality forecasting and special event monitoring. The HSRL channel will provide a demonstration of technology and a data testbed for direct extinction retrievals in support of ACE mission development. An overview of the instrument and mission will be provided, along with a summary of the science objectives and simulated data. Input from the ICAP community is desired to help plan our NRT mission goals and interactions with ICAP forecasters.

Welton, Ellsworth J.; McGill, Mathew J.; Yorks. John E.; Hlavka, Dennis L.; Hart, William D.; Palm, Stephen P.; Colarco, Peter R.

2012-01-01

203

Nd:YAG and ruby based lidar systems for remote sensing of atmospheric aerosols  

NASA Technical Reports Server (NTRS)

The application of solid-state lasers to the study of stratospheric and tropospheric aerosols is analyzed. A 48-inch mobile lidar which operates in the 0.6943, 1.06, 0.3472, and 0.5300 micron ranges is utilized to monitor the stratosphere. The detectors of the system consist of photomultipliers, and the dual-channel, computer-based data-acquisition-system which provides on-line plotting of scattering ratio profiles. The components of the 14-inch aperture, dual-wavelength airborne lidar system that operates with ruby and Nd:YAG transmitters are described. An 8-inch, down-looking airborne lidar with silicon diode or photomultiplier detectors was developed. The capabilities of the system alone and when combined with the 14-inch lidar are discussed. Examples of the data provided by the three lidar systems are presented, revealing the reliability and operational efficiency of the systems.

Fuller, W. H., Jr.

1985-01-01

204

Lidar determination of winds by aerosol inhomogeneities: motion velocity in the planetary boundary layer.  

PubMed

The paper presents results from lidar measurements of wind velocity in the planetary boundary layer using correlation data processing. Two lidars are used in our experiments: a ruby lidar operating along slant paths and a YAG:Nd lidar operating for near vertical sounding used by us for the first time. On the basis of our experience the optimal sizes of aerosol inhomogeneities (30-300 m), the duration of the experiments (2-10 min), and the repetition rate of laser shots (fractions of hertz to several hertz) are determined. The results are compared to independent data obtained from anemometer measurements, theodolite- and radar-tracked pilot balloons. The range of differences is ~1-2 m/s in speed and 10-15 degrees in direction. Preliminary results from the use of lidar data to remotely sound the wind speed for various atmospheric stratifications and synoptic situations are described as well. PMID:20531786

Kolev, I; Parvanov, O; Kaprielov, B

1988-06-15

205

Lidar mapping of a mixture of aerosol concentrations in a varying atmosphere  

NASA Technical Reports Server (NTRS)

In several recent applications dealing with lidar measurement of atmospheric pollution, two basic assumptions are made: (1)The investigated aerosol layer is the only particulate material within the scattering volume; and (2)The contribution of the gaseous atmosphere to the lidar backscattering signals can be estimated and deducted from the total backscattering measurements. In the method discussed a generalized method which allows the elimination of the above mentioned assumptions was developed using multiparameter lidar measurements. The different parameters can be several wavelengths, polarization of the scattered light, scattering angles, or any combination of these parameters. The basic requirements are given. The detailed derivations are presented and discussed.

Kleiman, M.; Egert, S.; Cohen, A.

1986-01-01

206

Remote sensing of seawater and drifting ice in Svalbard fjords by compact Raman lidar.  

PubMed

A compact Raman lidar system for remote sensing of sea and drifting ice was developed at the Wave Research Center at the Prokhorov General Physics Institute of the Russian Academy of Sciences. The developed system is based on a diode-pumped solid-state YVO(4):Nd laser combined with a compact spectrograph equipped with a gated detector. The system exhibits high sensitivity and can be used for mapping or depth profiling of different parameters within many oceanographic problems. Light weight (?20 kg) and low power consumption (300 W) make it possible to install the device on any vehicle, including unmanned aircraft or submarine systems. The Raman lidar presented was used for study and analysis of the different influence of the open sea and glaciers on water properties in Svalbard fjords. Temperature, phytoplankton, and dissolved organic matter distributions in the seawater were studied in the Ice Fjord, Van Mijen Fjord, and Rinders Fjord. Drifting ice and seawater in the Rinders Fjord were characterized by the Raman spectroscopy and fluorescence. It was found that the Paula Glacier strongly influences the water temperature and chlorophyll distributions in the Van Mijen Fjord and Rinders Fjord. Possible applications of compact lidar systems for express monitoring of seawater in places with high concentrations of floating ice or near cold streams in the Arctic Ocean are discussed. PMID:22859038

Bunkin, Alexey F; Klinkov, Vladimir K; Lednev, Vasily N; Lushnikov, Dmitry L; Marchenko, Aleksey V; Morozov, Eugene G; Pershin, Sergey M; Yulmetov, Renat N

2012-08-01

207

A Comparison Between Raman Lidar and Conventional Contact Measurements of Atmospheric Temperature  

NASA Technical Reports Server (NTRS)

Described here are the results of comparison between lidar and conventional contact measurements of the vertical temperature profile of the atmosphere. The lidar measurements are based on the method of temperature dependence of pure rotational Raman scattering of nitrogen and oxygen molecules. The presented results show that, as a whole, the motion of the lidar and conventional profiles coincide in the confidence intervals. Still there are districts in which the differences lay out of the confidence intervals. In analysis and estimation of the coincidence and the distinction in moving the profiles, we must take into account the differences between the methods for measuring the temperature profiles by lidar and contact methods, i.e. the next additional factors. The tied balloon meter gives the momentary values of the temperature in particular points of the profile, as these momentary values are the results of consequent, but not simultaneous measurements. In the case of free flying balloon, the time of measuring the lower several hundred meters is little because of high vertical velocity (about 300 m/min). This leads to an indefinite increase of the measuring error. The complete space coincidence between the lidar's and conventional profiles isn't possible. The contribution of the factors mentioned above about the error of comparison could increase because of nonstable layers in the planetary boundary layer of the atmosphere as well as by the influence of the mountains and the city situated nearby.

Mitev, V. M.; Simeonov, V. B.; Grigorov, I. V.

1992-01-01

208

Structure of an internal bore and dissipating gravity current as revealed by Raman lidar  

NASA Technical Reports Server (NTRS)

The Raman lidar observations of a weak gravity current and an internal bore associated with a thunderstorm gust front are presented. These observations have been complemented by conventional surface meteorologial analyses, special radiosonde data, spectral and bandpass filter analysis of barograph data, and infrared satellite imagery. Results obtained reveal the time-space continuity and dynamic nature of two boundary-layer disturbances seen in the lidar data. A comparison of the lidar display with the rawinsonde data makes it possible to determine the thermal fields associated with these disturbances at high temporal resolution (2 min) and an altitude of 6 km. The airflow associated with the disturbances was inferred by synthesizing the lidar and rawinsonde data. One of the two disturbances represents a dissipating outflow boundary (gust front) and can be characterized as a gravity current. The second disturbance represents an internal bore propagating ahead of the gravity current on a surface-based stable layer, which acted as a waveguide. The lidar revealed a mean bore depth of 1.9 km, observed and calculated speeds were in good agreement (about + or - 20 percent).

Koch, Steven E.; Melfi, S. H.; Skillman, William C.; Whiteman, D.; Dorian, Paul B.; Ferrare, R.

1991-01-01

209

Simulated lidar return from a one-dimensional stratospheric aerosol model  

NASA Technical Reports Server (NTRS)

Results are presented for theoretical calculations of lidar backscatter at wavelengths of 0.6943 and 1.06 microns from the stratospheric aerosol. The computations are based on the size distribution, particle number density, and particle composition predicted by a one-dimensional model of the stratospheric aerosol layer that assumes that the primary source of sulfur to the stratosphere is biogenic OCS released at ground level. The aerosol particles are taken to be spherical liquid H2SO4-H2O solution droplets with solid cores, which undergo condensation, evaporation, coagulation, sedimentation, and vertical eddy mixing. The theoretical backscatter profiles are compared with experimental results obtained from actual lidar observations of the stratospheric aerosol layer before and after the eruption of Volcan de Fuego in October 1974. The model predictions are shown to be in good agreement with the average of a number of observations.

Hamill, P.; Swissler, T. J.; Turco, R. P.; Toon, O. B.

1979-01-01

210

Remote sensing of the atmosphere by resonance Raman LIDAR  

SciTech Connect

With the increased environmental awareness has come the need for technologies that can detect, identify and monitor pollutants and, where necessary, verify their destruction. This need is evidenced by the recent creation of the Clean Air Act Amendments (CAAA), of which the Title 3-Hazardous Air Pollutants (HAP) amendments mandate the complete revision and expansion of the earlier Clean Air Act (CAA), section 112. As was pointed out by Grant, Kagann and McClenny, optical remote sensing technologies are expected to play a very important role in insuring that various facilities are in compliance with the Maximum Achievable Control Technology (MACT) standards for the reduction of HAP emissions that are called for in section 301 of Title 3. Unfortunately, however, many of these technologies have varying detection and applicability characteristics which often dictate the conditions under which one can use the sensor to detect, identify or monitor a chemical species. Some of the advantages that a Raman-based pollution sensor possess are: (1) very high selectivity (chemical specific fingerprints), (2) independence from the excitation wavelength (ability to monitor in the solar blind region), (3) chemical mixture fingerprints are the sum of its individual components (no spectral cross-talk), (4) near independence of the Raman fingerprint to its physical state (very similar spectra for gas, liquid, solid and solutions), and (5) insensitivity of the Raman signature to environmental conditions (no quenching, or interference from water). Early investigations were not able to take advantage of near-resonance enhancement of the Raman cross-section which occurs when the excitation frequency approaches an electronically excited state of the molecule. The enhancement of the scattering cross-section can be quite large, often approaching 4 to 6 orders of magnitude.

Sedlacek, A.J.; Harder, D.; Leung, K.P.; Zuhoski, P.B. Jr.; Burr, D.; Chen, C.L.

1995-01-01

211

IIP Update: A Packaged Coherent Doppler Wind Lidar Transceiver. Doppler Aerosol WiNd Lidar (DAWN)  

NASA Technical Reports Server (NTRS)

The state-of-the-art 2-micron coherent Doppler wind lidar breadboard at NASA/LaRC will be engineered and compactly packaged consistent with future aircraft flights. The packaged transceiver will be integrated into a coherent Doppler wind lidar system test bed at LaRC. Atmospheric wind measurements will be made to validate the packaged technology. This will greatly advance the coherent part of the hybrid Doppler wind lidar solution to the need for global tropospheric wind measurements.

Kavaya, Michael J.; Koch, Grady J.; Yu, Jirong; Trieu, Bo C.; Amzajerdian, Farzin; Singh, Upendra N.; Petros, Mulugeta

2006-01-01

212

Laser radar characterization of atmospheric aerosols in the troposphere and stratosphere using range dependent lidar ratio  

NASA Astrophysics Data System (ADS)

Laser radar (lidar) provides an excellent tool for characterizing the physical properties of atmospheric aerosols which play a very important role in modifying the radiative budget of the Earth's atmosphere. One of the important issues in lidar research is to derive accurate backscattering or extinction coefficient profiles required for understanding the basic mechanisms in the formation of aerosols and identifying their sources and sinks. Most of the inversion methods used for deriving the aerosol coefficients assume a range independent value for the extinction-to- backscattering ratio [lidar ratio, (LR)]. However, it is known that in a realistic atmosphere the value of LR is range dependent and varies with the physical and chemical properties of the aerosols. In this paper, we use a variant of widely applied Klett's method to obtain the range dependent LR values and derive the aerosol extinction profiles with good accuracy. We present the lidar derived aerosol extinction profiles in the upper troposphere and lower stratosphere corresponding to different seasons of the year of two distinctly different stations in the Indian subcontinent namely Trivandrum (8.33° N, 77° E), Kerala, India, a coastal station and Gadanki (13.5° N, 79.2° E), Tirupati, India an inland station. The range dependent LR is derived corresponding to different seasons of the year at the two stations. The lidar ratio, aerosol extinction coefficient (AEC), aerosol scattering ratio and aerosol optical depth show strong to medium seasonal variation at both the stations. The lidar ratio values at Trivandum vary in the range of 11-38 sr whereas the values range from 20-34 sr at Gadanki. AEC values at the Trivandum station vary from 7.9x10-6 to 6.9x10-5 m-1 and at Gadanki station the variation is from 1.27x10-5 to 6.9x10-5 m-1. It is proposed to use back-trajectory analysis to understand the sources of aerosol at the two stations.

Malladi, Satyanarayana; Soman Radha, Radhakrishnan; Mahadevan Pillai, V. P.; Sangipillai, Veerabuthiran; Bhargavan, Presennakumar; Vinjanampaty, Murty; Karnam, Reghunath

2010-01-01

213

A New Way to Measure Cirrus Ice Water Content by Using Ice Raman Scatter with Raman Lidar  

NASA Technical Reports Server (NTRS)

High and cold cirrus clouds mainly contain irregular ice crystals, such as, columns, hexagonal plates, bullet rosettes, and dendrites, and have different impacts on the climate system than low-level clouds, such as stratus, stratocumulus, and cumulus. The radiative effects of cirrus clouds on the current and future climate depend strongly on cirrus cloud microphysical properties including ice water content (IWC) and ice crystal sizes, which are mostly an unknown aspect of cinus clouds. Because of the natural complexity of cirrus clouds and their high locations, it is a challenging task to get them accurately by both remote sensing and in situ sampling. This study presents a new method to remotely sense cirrus microphysical properties by using ice Raman scatter with a Raman lidar. The intensity of Raman scattering is fundamentally proportional to the number of molecules involved. Therefore, ice Raman scattering signal provides a more direct way to measure IWC than other remote sensing methods. Case studies show that this method has the potential to provide essential information of cirrus microphysical properties to study cloud physical processes in cirrus clouds.

Wang, Zhien; Whiteman, David N.; Demoz, Belay; Veselovskii, Igor

2004-01-01

214

Airborne High Spectral Resolution Lidar Aerosol Measurements and Comparisons with Transport Models  

Microsoft Academic Search

The NASA Langley Research Center (LaRC) airborne High Spectral Resolution Lidar (HSRL) measured aerosol distributions and optical properties during several field experiments in 2006 and 2007. These experiments include: 1) the joint Megacity Initiative: Local and Global Research Observations (MILAGRO) \\/Megacity Aerosol Experiment in Mexico City (MAX-MEX)\\/Intercontinental Chemical Transport Experiment-B (INTEX B) experiment, 2) the Texas Air Quality Study (TEXAQS)\\/Gulf

R. Ferrare; C. Hostetler; J. Hair; A. Cook; D. Harper; S. Burton; M. Obland; R. Rogers; L. Kleinman; A. Clarke; J. Fast; M. Chin; G. Carmichael; Y. Tang; L. Emmons; B. Pierce; C. Kittaka

2007-01-01

215

Comparison of aerosol extinction profiles from lidar and SAGE II data at a tropical station  

NASA Technical Reports Server (NTRS)

Aerosol extinction profiles obtained from lidar data at Trivandrum (8.6 deg N, 77 deg E) are compared with corresponding Stratospheric Aerosol and Gas Experiment II extinction profiles. The agreement between the two is found to be satisfactory. The extinction profiles obtained by both the experiments showed a prominent peak at 23-24 km altitude in the stratosphere. The study revealed large variability in upper tropospheric extinction with location (latitude).

Parameswaran, K.; Rose, K. O.; Murthy, B. V. K.; Osborn, M. T.; Mcmaster, L. R.

1991-01-01

216

Portable digital lidar: a compact stand-off bioagent aerosol sensor  

NASA Astrophysics Data System (ADS)

Remote detection of biological warfare agents (BWA) is crucial for providing early warning to ensure maximum survivability of personnel in the battlefield and other sensitive areas. Although the current generation of stand- off aerosol and fluorescence lidars have demonstrated stand- off detection and identification of BWA, their large size and cost make them difficult for field use. We have introduced a new eye-safe portable digital lidar (PDL) technique based on digital detection that achieves orders of magnitude reduction in the size, cost and complexity over the conventional lidar, while providing an equal or better sensitivity and range. Excellent performance has been obtained with two of our PDL sensors during two bio-aerosol measurement campaigns carried out at Dugway Proving Grounds. In the JFT 4.5 (Oct 98) tests, high aerosol sensitivity of 300 ppl of biosimulant particles at up to 3 km was demonstrated with an eye-safe wavelength (523nm) aerosol micro PDL that utilized a 8 inch telescope, <10(mu) J/pulse energy at 2.5kHz, photon counting digital detection and 2 sec averaging. For the JBREWS DFT (June 99) tests an eye-safe two wavelengths (523nm and 1.047mum) horizontally scanned, aerosol micro PDL with the same 8 inch telescope was utilized. With this lidar, high sensitivity, preliminary differentiation between natural and unusual clouds, and the ability to track the aerosol cloud location, their wind speed and direction were also demonstrated. Lidar simulations of both PDL and conventional analog detection have been performed. Based on these model calculations and experimental results an analysis and comparison of the inherent capabilities of two types of systems is given.

Prasad, Coorg R.; Lee, Hyo Sang; Hwang, In H.; Nam, Matthew; Mathur, Savyasachee L.; Ranganayakamma, Belthur

2001-08-01

217

Fluorescence from atmospheric aerosol detected by a lidar indicates biogenic particles in the stratosphere  

NASA Astrophysics Data System (ADS)

With a lidar system that was installed in Lindenberg/Germany, we observed in June 2003, an extended aerosol layer at 13 km altitude in the lowermost stratosphere. This layer created an inelastic backscatter signal which we interpret as laser induced fluorescence from aerosol particles. Also, we find evidence for inelastic scattering in a smoke plume from a forest fire that we observed in the troposphere. Fluorescence from ambient aerosol had not yet been considered detectable by lidar. However, organic compounds such as polycyclic aromatic hydrocarbons sticking to the aerosol particles, or bioaerosol such as bacteria, spores or pollen fluoresce when excited with UV-radiation in a way that is detectable by our lidar system. Therefore, we conclude that fluorescence from organic material released by biomass burning creates the inelastic backscatter signal that we measured with our instrument and thus demonstrate a new and powerful way to characterize aerosols by a remote sensing technique. The stratospheric aerosol layer that we have observed in Lindenberg for three consecutive days is likely to be a remnant from Siberian forest fire plumes lifted across the tropopause and transported around the globe.

Immler, F.; Engelbart, D.; Schrems, O.

2004-09-01

218

Comments on: Accuracy of Raman Lidar Water Vapor Calibration and its Applicability to Long-Term Measurements  

NASA Technical Reports Server (NTRS)

In a recent publication, LeBlanc and McDermid proposed a hybrid calibration technique for Raman water vapor lidar involving a tungsten lamp and radiosondes. Measurements made with the lidar telescope viewing the calibration lamp were used to stabilize the lidar calibration determined by comparison with radiosonde. The technique provided a significantly more stable calibration constant than radiosondes used alone. The technique involves the use of a calibration lamp in a fixed position in front of the lidar receiver aperture. We examine this configuration and find that such a configuration likely does not properly sample the full lidar system optical efficiency. While the technique is a useful addition to the use of radiosondes alone for lidar calibration, it is important to understand the scenarios under which it will not provide an accurate quantification of system optical efficiency changes. We offer examples of these scenarios.

Whiteman, David N.; Venable, Demetrius; Landulfo, Eduardo

2012-01-01

219

Comparison of Aerosol optical depth (AOD) derived from AERONET sunphotometer and Lidar system  

NASA Astrophysics Data System (ADS)

Aerosol optical depth (AOD) is the measure of aerosols distributed within a column of air from the instrument or Earth's surface to the top of the atmosphere. In this paper, we compared the AOD measured by the Raymetrics Lidar system and AERONET sunphotometer. A total of 6 days data which was collected by both instruments were compiled and compared. Generally, AOD value calculated from Lidar data are higher than that calculated from AERONET data. Differences and similarities in the AOD data trend were observed and the corresponding explanations were done. Level 1.5 data of AERONET is estimated to have an accuracy of ±0.03, thus the Lidar data should follow the trend of the AERONET. But in this regards, this study was conducted less than one month and was very difficult to justify the differences and similarities between AOD measured by the Raymetrics Lidar system and AERONET sunphotometer. So further studies for an extended period will be needed and performed with more comprehensive LIDAR measurements. The slope of the best-fit straight line for the data points between the AOD values retrieved from LIDAR and the AERONET measurements is the closest to unity and the coefficient of determination is high (above 0. 6692). Factors which affect AOD data were discussed. As a conclusion, the trends of the AOD of both systems are similar. Yet due to some external factors, the trend will be slightly different.

Khor, Wei Ying; Shen Hee, Wan; Tan, Fuyi; San Lim, Hwee; Zubir Mat Jafri, Mohamad; Holben, Brent

2014-06-01

220

Retrievals of Profiles of Fine And Coarse Aerosols Using Lidar And Radiometric Space Measurements  

NASA Technical Reports Server (NTRS)

In couple of years we expect the launch of the CALIPSO lidar spaceborne mission designed to observe aerosols and clouds. CALIPSO will collect profiles of the lidar attenuated backscattering coefficients in two spectral wavelengths (0.53 and 1.06 microns). Observations are provided along the track of the satellite around the globe from pole to pole. The attenuated backscattering coefficients are sensitive to the vertical distribution of aerosol particles, their shape and size. However the information is insufficient to be mapped into unique aerosol physical properties and vertical distribution. Infinite number of physical solutions can reconstruct the same two wavelength backscattered profile measured from space. CALIPSO will fly in formation with the Aqua satellite and the MODIS spectro-radiometer on board. Spectral radiances measured by MODIS in six channels between 0.55 and 2.13 microns simultaneously with the CALIPSO observations can constrain the solutions and resolve this ambiguity, albeit under some assumptions. In this paper we describe the inversion method and apply it to aircraft lidar and MODIS data collected over a dust storm off the coast of West Africa during the SHADE experiment. It is shown that the product of the single scattering albedo, omega, and the phase function, P, for backscattering can be retrieved from the synergism between measurements avoiding a priori hypotheses required for inverting lidar measurements alone. The resultant value of (omega)P(180 deg.) = 0.016/sr are significantly different from what is expected using Mie theory, but are in good agreement with recent results obtained from lidar observations of dust episodes. The inversion is robust in the presence of noise of 10% and 20% in the lidar signal in the 0.53 and 1.06 pm channels respectively. Calibration errors of the lidar of 5 to 10% can cause an error in optical thickness of 20 to 40% respectively in the tested cases. The lidar calibration errors cause degradation in the ability to fit the MODIS data. Therefore the MODIS measurements can be used to identify the calibration problem and correct for it. The CALIPSO-MODIS measurements of the profiles of fine and coarse aerosols, together with CALIPSO measurements of clouds vertical distribution, is expected to be critically important in understanding aerosol transport across continents and political boundaries, and to study aerosol-cloud interaction and its effect on precipitation and global forcing of climate.

Kaufman, Yoram; Tanre, Didier; Leon, Jean-Francois; Pelon, Jacques; Lau, William K. M. (Technical Monitor)

2002-01-01

221

Comparison of Modeled Backscatter using Measured Aerosol Microphysics with Focused CW Lidar Data over Pacific  

NASA Technical Reports Server (NTRS)

During NASA's GLObal Backscatter Experiment (GLOBE) II flight mission over the Pacific Ocean in May-June 1990, extensive aerosol backscatter data sets from two continuous wave, focused CO2 Doppler lidars and an aerosol microphysics data set from a laser optical particle counter (LOPC) were obtained. Changes in aerosol loading in various air masses with associated changes in chemical composition, from sulfuric acid and sulfates to dustlike crustal material, significantly affected aerosol backscatter, causing variation of about 3 to 4 orders of magnitude. Some of the significant backscatter features encountered in different air masses were the low backscatter in subtropical air with even lower values in the tropics near the Intertropical Convergence Zone (ITCZ), highly variable backscatter in the ITCZ, mid-tropospheric aerosol backscatter background mode, and high backscatter in an Asian dust plume off the Japanese coast. Differences in aerosol composition and backscatter for northern and southern hemisphere also were observed. Using the LOPC measurements of physical and chemical aerosol properties, we determined the complex refractive index from three different aerosol mixture models to calculate backscatter. These values provided a well-defined envelope of modeled backscatter for various atmospheric conditions, giving good agreement with the lidar data over a horizontal sampling of approximately 18000 km in the mid-troposphere.

Srivastava, Vandana; Clarke, Antony D.; Jarzembski, Maurice A.; Rothermel, Jeffry

1997-01-01

222

NASA LaRC airborne high spectral resolution lidar aerosol measurements during MILAGRO: observations and validation  

Microsoft Academic Search

The NASA Langley Research Center (LaRC) airborne High Spectral Resolution Lidar (HSRL) measures vertical profiles of aerosol extinction, backscatter, and depolarization at both 532 nm and 1064 nm. In March of 2006 the HSRL participated in the Megacity Initiative: Local and Global Research Observations (MILAGRO) campaign along with several other suites of instruments deployed on both aircraft and ground based

R. R. Rogers; J. W. Hair; C. A. Hostetler; R. A. Ferrare; M. D. Obland; A. L. Cook; D. B. Harper; S. P. Burton; Y. Shinozuka; C. S. McNaughton; A. D. Clarke; J. Redemann; P. B. Russell; J. M. Livingston; L. I. Kleinman

2009-01-01

223

Aerosol and cloud interaction observed from high spectral resolution lidar data  

Microsoft Academic Search

Recent studies utilizing satellite retrievals have shown a strong correlation between aerosol optical depth (AOD) and cloud cover. However, these retrievals from passive sensors are subject to many limitations, including cloud adjacency (or three-dimensional) effects, possible cloud contamination, uncertainty in the AOD retrieval. Some of these limitations do not exist in High Spectral Resolution Lidar (HSRL) observations; for instance, HSRL

Wenying Su; Gregory L. Schuster; Norman G. Loeb; Raymond R. Rogers; Richard A. Ferrare; Chris A. Hostetler; Johnathan W. Hair; Michael D. Obland

2008-01-01

224

AIRBORNE HIGH SPECTRAL RESOLUTION LIDAR AEROSOL MEASUREMENTS DURING CALNEX AND CARES  

E-print Network

(LaRC) airborne high spectral resolution lidar (HSRL) on the NASA B-200 aircraft measured aerosol the 2010 CalNex and CARES field missions. During the CalNex deployment in May 2010, HSRL data were acquired in June 2010, HSRL data were acquired during 23 science flights that were located mainly over Sacramento

225

Aerosol Transport Questions Arising From Micro Pulse Lidar Measurements During MILAGRO  

Microsoft Academic Search

A Micro Pulse Lidar (MPL) was operated by Argonne National Laboratory at the Universidad de Tecámac site (T1) during the MILAGRO field campaign in March 2006 in the environs of Mexico City. Located approximately 40 km north of the urban center of Mexico City, the T1 site was expected to observe the transport and evolution of aerosols as they moved

R. Kotamarthi; R. Coulter; M. Pekour

2007-01-01

226

Doppler Lidar Measurements of Tropospheric Wind Profiles Using the Aerosol Double Edge Technique  

NASA Technical Reports Server (NTRS)

The development of a ground based direct detection Doppler lidar based on the recently described aerosol double edge technique is reported. A pulsed, injection seeded Nd:YAG laser operating at 1064 nm is used to make range resolved measurements of atmospheric winds in the free troposphere. The wind measurements are determined by measuring the Doppler shift of the laser signal backscattered from atmospheric aerosols. The lidar instrument and double edge method are described and initial tropospheric wind profile measurements are presented. Wind profiles are reported for both day and night operation. The measurements extend to altitudes as high as 14 km and are compared to rawinsonde wind profile data from Dulles airport in Virginia. Vertical resolution of the lidar measurements is 330 m and the rms precision of the measurements is a low as 0.6 m/s.

Gentry, Bruce M.; Li, Steven X.; Mathur, Savyasachee; Korb, C. Laurence; Chen, Huailin

2000-01-01

227

Lidar Monitoring of Clouds and Aerosols at the Facility for Atmospheric Remote Sensing  

NASA Technical Reports Server (NTRS)

We report on findings from ongoing polarization lidar research at the University of Utah Facility for Atmospheric Remote Sensing (FARS). This facility was established in 1987, and the current total of lidar and radiometric measurements is approx. 2,900-h. Research at FARS has been applied to the climatological investigation of cirrus cloud properties for basic research and satellite measurement validation (currently in its 13th year), and studies of contrails, mixed phase clouds, and volcanic and Asian dust aerosols. Among the techniques utilized for monitoring cloud and aerosol properties are triple-wave length linear depolarization measurements, and high (1.5-m by 10-Hz) resolution scanning observations. The usefulness of extended time lidar studies for atmospheric and climate research is illustrated.

Sassen, Kenneth

2000-01-01

228

Lidar System for Airborne Measurement of Clouds and Aerosols  

NASA Technical Reports Server (NTRS)

A lidar system for measuring optical properties of clouds and aerosols at three wavelengths is depicted. The laser transmitter is based on a Nd:YVO4 laser crystal pumped by light coupled to the crystal via optical fibers from laser diodes that are located away from the crystal to aid in dissipating the heat generated in the diodes and their drive circuits. The output of the Nd:YVO4 crystal has a wavelength of 1064 nm, and is made to pass through frequency-doubling and frequency-tripling crystals. As a result, the net laser output is a collinear superposition of beams at wavelengths of 1064, 532, and 355 nm. The laser operates at a pulse-repetition rate of 5 kHz, emitting per-pulse energies of 50 microJ at 1064 nm, 25 microJ at 532 nm and 50 microJ at 355 nm. An important feature of this system is an integrating sphere located between the laser output and the laser beam expander lenses. The integrating sphere collects light scattered from the lenses. Three energy-monitor detectors are located at ports inside the integrating sphere. Each of these detectors is equipped with filters such that the laser output energy is measured independently for each wavelength. The laser output energy is measured on each pulse to enable the most accurate calibration possible. The 1064-nm and 532-nm photodetectors are, more specifically, single photon-counting modules (SPCMs). When used at 1064 nm, these detectors have approximately 3% quantum efficiency and low thermal noise (fewer than 200 counts per second). When used at 532 nm, the SPCMs have quantum efficiency of about 60%. The photodetector for the 355-nm channel is a photon-counting photomultiplier tube having a quantum efficiency of about 20%. The use of photon-counting detectors is made feasible by the low laser pulse energy. The main advantage of photon-counting is ease of inversion of data without need for complicated calibration schemes like those necessary for analog detectors. The disadvantage of photon-counting detectors is that they inherently have narrow dynamic ranges. However, by using photon-counting detectors along with a high-repetition rate laser, it is possible to obtain wide dynamic range through accumulation of counts over many pulses.

McGill, Matthew; Scott, V. Stanley; Izquierdo, Luis Ramos; Marzouk, Joe

2008-01-01

229

Assimilation of lidar signals: application to aerosol forecasting in the Mediterranean Basin  

NASA Astrophysics Data System (ADS)

This paper presents a new application of assimilating lidar signals to aerosol forecasting. It aims at investigating the impact of a ground-based lidar network on analysis and short-term forecasts of aerosols through a case study in the Mediterranean. To do so, we employ a data assimilation (DA) algorithm based on the optimal interpolation method developed in the chemistry transport model (CTM) {Polair3D of the air quality modelling platform POLYPHEMUS. We assimilate hourly-averaged normalised range corrected lidar signals (PR2) retrieved from a 72 h period of intensive and continuous measurements performed in July 2012 by ground-based lidar systems of the European Aerosol Research Lidar Network (EARLINET) integrated into the Aerosols, Clouds, and Trace gases Research InfraStructure Network (ACTRIS) and an additional system in Corsica deployed in the framework of the pre-ChArMEx (Chemistry-Aerosol Mediterranean Experiment)/TRAQA (TRAnsport à longue distance et Qualité de l'Air) campaign. This lidar campaign was dedicated to demonstrating the potential operationality of a research network like EARLINET and the potential usefulness of assimilation of lidar signals to aerosol forecasts. Particles with an aerodynamic diameter lower than 2.5 ?m (PM2.5) and those with an aerodynamic diameter higher than 2.5 ?m but lower than 10 ?m (PM2.5-10) are analysed separately using the lidar observations at each DA step. First, we study the spatial and temporal influences of the assimilation of lidar signals on aerosol forecasting. We conduct sensitivity studies on algorithmic parameters, e.g. the horizontal correlation length (Lh) used in the background error covariance matrix (50 km, 100 km or 200 km), the altitudes at which DA is performed (0.75-3.5 km, 1.0-3.5 km or 1.5-3.5 km a.g.l.) and the assimilation period length (12 h or 24 h). We find that DA with Lh = 100 km and assimilation from 1.0 to 3.5 km a.g.l. during a 12 h assimilation period length leads to the best scores for PM10 and PM2.5 during the forecast period with reference to available measurements from surface networks. Secondly, the aerosol simulation results without and with lidar DA using the optimal parameters (Lh = 100 km, the assimilation altitude range from 1.0 to 3.5 {km a.g.l.} and 12 h DA period) are evaluated using the Level 2.0 (cloud-screened and quality-assured) Aerosol Optical Depth (AOD) data from AERONET, and mass concentration measurements (PM10 or PM2.5) from the French air quality network (BDQA) and the EMEP-Spain/Portugal network. The results show that the simulation with DA leads to better scores than the one without DA for PM2.5, PM10 and AOD. Additionally, the comparison of model results to evaluation data indicates that the temporal impact of assimilating lidar signals is longer than 36 h after the assimilation period.

Wang, Y.; Sartelet, K. N.; Bocquet, M.; Chazette, P.; Sicard, M.; D'Amico, G.; Léon, J. F.; Alados-Arboledas, L.; Amodeo, A.; Augustin, P.; Bach, J.; Belegante, L.; Binietoglou, I.; Bush, X.; Comerón, A.; Delbarre, H.; García-Vízcaino, D.; Guerrero-Rascado, J. L.; Hervo, M.; Iarlori, M.; Kokkalis, P.; Lange, D.; Molero, F.; Montoux, N.; Muñoz, A.; Muñoz, C.; Nicolae, D.; Papayannis, A.; Pappalardo, G.; Preissler, J.; Rocadenbosch, F.; Sellegri, K.; Wagner, F.; Dulac, F.

2014-05-01

230

Development of a High Spectral Resolution Lidar (HSRL) Based on a Confocal Optical Filter for Aerosol Studies  

Microsoft Academic Search

Aerosols are an important constituent in atmospheric composition affecting climate, weather, and air quality. Active remote sensing instruments provide tools for in-situ studies of atmospheric aerosols that can help understand the role of aerosols on the radiative forcing of the climate system. In this paper, the design and initial performance of a high spectral resolution lidar (HSRL) based on a

K. S. Repasky; D. S. Hoffman; J. A. Reagan; J. Carlsten

2010-01-01

231

Dust aerosol optical properties using ground-based and airborne lidar in the framework of FENNEC  

NASA Astrophysics Data System (ADS)

The FENNEC program aims to improve our knowledge of both the role of the Saharan Heat Low (SHL) on the West African monsoon and the interactions between the African continent and the Mediterranean basin through the Saharan dust transport. The Saharan desert is the major source of mineral dust in the world and may significantly impact the air quality over the Western Europe by increasing the particular matter content. Two lidar systems were operated by the French component of the FENNEC project: an airborne lidar which was flown aboard the French Falcon 20 research aircraft and a ground-based lidar which was located in the southeastern part of Spain, close to Marbella. The presence of dust in the Saharan atmospheric boundary layer has been easily highlighted using the lidars and confirmed by ground-based sunphotometer and observations from both MODIS and SEVIRI spaceborne instruments. The simultaneous use of the sunphotometer-derived Angstrom exponent and the lidar-derived backscatter to extinction ratio is appeared to be a good approach to separate the optical contribution of dust from local aerosols for the coastal site. Over Spain, the dust layer was mainly located above the planetary boundary layer with several kilometers thick. Over the tropical Atlantic Ocean and the Mauritania the airborne lidar shows a high planetary boundary layer (~5 km above the mean sea level) associated to strong aerosol optical thickness (> 0.8 at 532 nm). The airborne lidar data have been inverted using both MODIS and SEVIRI-derived aerosol optical thickness. The differences between dust optical properties close to and remote from the sources will be discussed.

Marnas, Fabien; Chazette, Patrick; Flamant, Cyrille; Royer, Philippe; Boytard, Mai-Lan; Genau, Pascal; Doira, Pascal; Bruneau, Didier; Pelon, Jacques; Sanak, Joseph

2013-04-01

232

Lidar aerosol backscatter cross sections in the 2-{mu}m near-infrared wavelength region  

SciTech Connect

Lidar backscatter cross-sectional measurements at 1.064, 0.532, and 1.54 {mu}m were acquired during November 1989 and May{endash}June 1990 around the Pacific region by the NASA DC-8 aircraft as part of the Global Backscatter Experiment. The primary motivation for the Global Backscatter Experiment was the study of lidar backscatter cross sections for the development of a spaceborne wind-sensing lidar. Direct backscatter measurements obtained by the NASA Goddard Space Flight Center visible and infrared lidar are compared with backscatter cross sections calculated from aerosol size distributions obtained by particle counters. Results for one flight with pronounced aerosol layers in the upper troposphere southeast of Japan are presented. Because 2-{mu}m region wavelengths are possible candidates for a spaceborne wind-sensing lidar, the visible and infrared lidar backscatter cross sections at 1.064, 0.532, and 1.54 {mu}m are extrapolated to the 2-{mu}m region. The extrapolated 2-{mu}m cross sections are compared with lidar measurements at 9 {mu}m. A significant range in the ratio of 2{endash}9-{mu}m backscatter cross sections is found, but a large number of points concentrate near ratios of three to ten. A large number of 1.064- and 1.54-{mu}m cross sections were binned to provide an estimate of backscatter for various percentiles for the flight. The ratio of the 50-percentile backscatter values at 1.064 and 1.54 {mu}m suggest a {lambda}{sup {minus}1.9} to {lambda}{sup {minus}3.0} wavelength dependence of aerosol backscatter cross section in the near infrared for the observational case. {copyright} {ital 1996 Optical Society of America.}

Chudamani, S. [Science Systems Applications, Inc., Lanham, Maryland 20706 (United States); Spinhirne, J.D. [Laboratory for Atmospheres, NASA Goddard Space Flight Center, Greenbelt, Maryland 20771 (United States); Clarke, A.D. [Department of Oceanography, University of Hawaii, Honolulu, Hawaii 96822 (United States)

1996-08-01

233

Lidar aerosol backscatter cross sections in the 2-?m near-infrared wavelength region.  

PubMed

Lidar backscatter cross-sectional measurements at 1.064, 0.532, and 1.54 ?m were acquired during November 1989 and May-June 1990 around the Pacific region by the NASA DC-8 aircraft as part of the Global Backscatter Experiment. The primary motivation for the Global Backscatter Experiment was the study of lidar backscatter cross sections for the development of a spaceborne wind-sensing lidar. Direct backscatter measurements obtained by the NASA Goddard Space Flight Center visible and infrared lidar are compared with backscatter cross sections calculated from aerosol size distributions obtained by particle counters. Results for one flight with pronounced aerosol layers in the upper troposphere southeast of Japan are presented. Because 2-?m region wavelengths are possible candidates for a spaceborne wind-sensing lidar, the visible and infrared lidar backscatter cross sections at 1.064, 0.532, and 1.54 ?m are extrapolated to the 2-?m region. The extrapolated 2-?m cross sections are compared with lidar measurements at 9 ?m. A significant range in the ratio of 2-9-?m backscatter cross sections is found, but a large number of points concentrate near ratios of three to ten. A large number of 1.064- and 1.54-?m cross sections were binned to provide an estimate of backscatter for various percentiles for the flight. The ratio of the 50-percentile backscatter values at 1.064 and 1.54 ?m suggest a ?(-1.9) to ?(-3.0) wavelength dependence of aerosol backscatter cross section in the near infrared for the observational case. PMID:21102906

Chudamani, S; Spinhirne, J D; Clarke, A D

1996-08-20

234

Development of a 9.3 micrometer CW LIDAR for the study of atmospheric aerosol  

NASA Technical Reports Server (NTRS)

This report provides a brief summary of the basic requirements to obtain coherent or heterodyne mixing of the optical radiation backscattered by atmospheric aerosols with that from a fixed frequency source. The continuous wave (CW) mode of operation for a coherent lidar is reviewed along with the associated lidar transfer equation. A complete optical design of the three major subsystems of a CW, coherent lidar is given. Lens design software is implemented to model and optimize receiver performance. Techniques for the opto-mechanical assembly and some of the critical tolerances of the coherent lidar are provided along with preliminary tests of the subsystems. Included in these tests is a comparison of the experimental and the theoretical average power signal-to-noise ratio. The analog to digital software used to evaluate the power spectrum of the backscattered signal is presented in the Appendix of this report.

Whiteside, B. N.; Schotland, R. M.

1993-01-01

235

Aerosol and Cloud Interaction Observed from High Spectral Resolution Lidar  

Microsoft Academic Search

Studies have shown that aerosol optical depth is higher in the vicinity of clouds than in the clear air between clouds. The possible causes for this increased aerosol optical depth have been attributed to cloud contamination, swelling of aerosols as humidity increases in the vicinity of clouds, scattering from clouds into adjacent cloud-free columns, increased particle production near clouds, and

W. Su; G. L. Schuster; N. G. Loeb; R. R. Rogers; R. A. Ferrare; J. W. Hair; C. A. Hostetler; M. D. Obland

2008-01-01

236

Evaluation of LIDAR/Polarimeter Aerosol Measurements by In Situ Instrumentation during DEVOTE  

NASA Astrophysics Data System (ADS)

Combined measurements from LIDAR (LIght Detection And Ranging) and polarimeter instruments provide the opportunity for enhanced satellite observations of aerosol properties including retrievals of aerosol optical depth, single scattering albedo, effective radius, and refractive index. However, these retrievals (specifically for refractive index) have not been fully vetted and require additional intercomparisons with in situ measurements to improve accuracy. Proper validation of these combined LIDAR/polarimeter retrievals requires evaluation in varying atmospheric conditions and of varying aerosol composition. As part of this effort, two NASA Langley King Air aircraft have been outfitted to provide coordinated measurements of aerosol properties. One will be used as a remote sensing platform with the NASA Langley high-spectral resolution LIDAR (HSRL) and NASA GISS research scanning polarimeter (RSP). The second aircraft has been modified for use as an in situ platform and will house a suite of aerosol microphysical instrumentation, a pair of diode laser hygrometers (DLHs) for water vapor and cloud extinction measurements, and a polarized imaging nephelometer (PI-Neph). The remote sensing package has flown in a variety of campaigns, however only rarely has been able to coordinate with in situ measurements. The use of two collocated aircraft will allow for future coordinated flights to provide a more complete dataset for evaluation of aerosol retrievals and allow for fast-response capability. Results from the first coordinated King Air flights as part of DEVOTE (Development and Evaulation of satellite ValidatiOn Tools by Experimenters) will be presented. Flights are planned out of Hampton, VA during September and October 2011 including underflights of the CALIPSO satellite and overflights of ground-based AERONET (AErosol RObotic NETwork) sites. These will provide a comparison of aerosol properties between in situ and remote instruments (ground, aircraft, and satellite-based). In situ measurements include aerosol number density, size, scattering, absorption and hygroscopicity (aerosol scattering as a function of relative humidity). The PI-Neph will provide the first airborne in situ measurements of aerosol polarized phase function for comparison to the RSP retrievals. As this is the first airborne use of the PI-Neph, aerosol scattering measurements from the PI-Neph will be compared to an integrating nephelometer to provide a primary indication of instrument functionality. Specific flights will be performed to study a range of aerosol classifications including fresh anthropogenic pollution (flights over populated regions), aged pollution (tracking pollution as it moves off shore), sea salt (low altitude ocean flights by the in situ aircraft) and biogenic (flights over forest canopies). In addition, the DLH and a wing-mounted cloud aerosol precipitation spectrometer will provide insight into aerosol retrievals above and near clouds.

Beyersdorf, A. J.; Ziemba, L. D.; Anderson, B. E.; Dolgos, G.; Ottaviani, M.; Obland, M. D.; Rogers, R.; Thornhill, K. L.; Winstead, E. L.; Yang, M. M.; Hair, J. W.

2011-12-01

237

CALIPSO: Global Aerosol and Cloud Observations from Lidar and Passive Instruments  

NASA Technical Reports Server (NTRS)

CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Spaceborne Observations) is an approved satellite mission being developed through collaboration between NASA and the French space agency CNES. The mission is scheduled for launch in 2004 and will operate for 3 years as part of a five-satellite formation called the Aqua constellation. This constellation will provide a unique data set on aerosol and cloud optical and physical properties and aerosol-cloud interactions that will substantially increase our understanding of the climate system and the potential for climate change.

Poole, L. R.; Winker, D. M.; Pelon, J. R.; McCormick, M. P.

2002-01-01

238

Absolute calibration of LIDAR Thomson scattering systems by rotational Raman scattering.  

PubMed

Absolute calibration of LIDAR Thomson scattering systems on large fusion devices may be achieved using rotational Raman scattering. The choice of calibrating gas molecule presents different options and design trade-offs and is likely to be strongly dependent on the laser wavelength selected. Raman scattering of hydrogenic molecules produces a very broad spectrum, however, with far fewer scattered photons than scattering from nitrogen or oxygen at the same gas pressure. Lower laser wavelengths have the advantage that the Raman cross section increases, sigma(Raman) proportional to 1/lambda(0)(4), but the disadvantage that the spectral width of the scattered spectrum decreases, Deltalambda(Raman) proportional to lambda(0)(2). This narrower spectrum makes measurement closer to the laser wavelength necessary. The design of the calibration technique presents a number of challenges. Some of these challenges are generic to all Thomson scattering systems. These include detecting a sufficient number of photoelectrons and designing filters that measure close to the laser wavelength while simultaneously achieving adequate blocking of the laser wavelength. An issue specific to LIDAR systems arises since the collection optics operates over a wide range of depth of field. This wide depth of field has the effect of changing the angle of light incident on the optical interference filter with plasma major radius. The angular distribution then determines the effective spectral transmission function of the interference filter and hence impacts on the accuracy of the absolute calibration. One method that can be used to increase absolute calibration accuracy is collecting both Stokes and anti-Stokes lines with optical filter transmission bands specifically designed to reduce systematic uncertainty. PMID:20441368

Scannell, R; Beurskens, M; Kempenaars, M; Naylor, G; Walsh, M; O'Gorman, T; Pasqualotto, R

2010-04-01

239

Absolute calibration of LIDAR Thomson scattering systems by rotational Raman scattering  

SciTech Connect

Absolute calibration of LIDAR Thomson scattering systems on large fusion devices may be achieved using rotational Raman scattering. The choice of calibrating gas molecule presents different options and design trade-offs and is likely to be strongly dependent on the laser wavelength selected. Raman scattering of hydrogenic molecules produces a very broad spectrum, however, with far fewer scattered photons than scattering from nitrogen or oxygen at the same gas pressure. Lower laser wavelengths have the advantage that the Raman cross section increases, {sigma}{sub Raman}{proportional_to}1/{lambda}{sub 0}{sup 4}, but the disadvantage that the spectral width of the scattered spectrum decreases, {Delta}{lambda}{sub Raman}{proportional_to}{lambda}{sub 0}{sup 2}. This narrower spectrum makes measurement closer to the laser wavelength necessary. The design of the calibration technique presents a number of challenges. Some of these challenges are generic to all Thomson scattering systems. These include detecting a sufficient number of photoelectrons and designing filters that measure close to the laser wavelength while simultaneously achieving adequate blocking of the laser wavelength. An issue specific to LIDAR systems arises since the collection optics operates over a wide range of depth of field. This wide depth of field has the effect of changing the angle of light incident on the optical interference filter with plasma major radius. The angular distribution then determines the effective spectral transmission function of the interference filter and hence impacts on the accuracy of the absolute calibration. One method that can be used to increase absolute calibration accuracy is collecting both Stokes and anti-Stokes lines with optical filter transmission bands specifically designed to reduce systematic uncertainty.

Scannell, R.; Beurskens, M.; Kempenaars, M.; Naylor, G. [EURATOM/CCFE Fusion Association, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Walsh, M. [CHD Department, Diagnostics Division, ITER Organisation, Cadarache, 13106 St. Paul-lez-Durance (France); O'Gorman, T. [Department of Electrical and Electronic Engineering, University College Cork, Cork (Ireland); Pasqualotto, R. [Consorzio RFX-Associazione Euratom-Enea sulla Fusione, Corso Stati Uniti 4, I-35127 Padova (Italy)

2010-04-15

240

Study of lidar and satellite data on stratospheric aerosols formed due to Mt. Pinatubo volcanic eruption  

NASA Astrophysics Data System (ADS)

Lidar aerosol backscatter data of a few stations published in Bulletin of Global Volcanism Network (USA) (1991) have been used to investigate various transport/dynamical processes and also aerosol loading in the stratosphere due to the 15 June 1991 Pinatubo volcanic eruption. Some recently reported satellite observations have also been used to support the results obtained. Satellite data showed that in the zone extending 10 deg N from equator, Pinatubo aerosols circled the globe in 21 days, implying a mean easterly speed of 20-22 m/s. Ground-based lidar observations showed that aerosol cloud spread northward faster in low midlatitudes and slowly in higher midlatitudes. The stratospheric aerosol loading due to Pinatubo was about 30 times the preeruption value at a low latitude station (Mauna Loa) and about 4 times at a higher midlatitude station (Obninsk). The analysis further showed that the aerosol cloud due to Pinatubo was nearly 1.5 times than that produced due to the 1982 El Chichon volcanic eruption. The presence and morphology of of the multiple stratospheric aerosol layers that appeared over Mauna Loa in the aftermath of Pinatubo are discussed.

Raj, P. E.; Devara, P. C. S.

1993-02-01

241

Mid-latitude Rayleigh-Mie-Raman Lidar for Observations from 15 to 120 km  

NASA Astrophysics Data System (ADS)

The original Rayleigh scatter lidar system that ran from 1993-2004 at the Atmospheric Lidar Observatory (ALO; 41.7° N, 111.8° W) in the Center for Atmospheric and Space Sciences (CASS) on the campus of Utah State University (USU) is undergoing a series of upgrades to transform it into a Rayleigh-Mie-Raman (RMR) scatter lidar. The original lidar covered the mesosphere from 45 to 90 km. The upgraded system will cover the region from approximately 15 to 120 km. The scientific impetus for these upgrades is to enable measurements of densities and temperatures throughout the middle atmosphere, covering most of the stratosphere, all of the mesosphere and well into the lower thermosphere. Initially, at the upper end, this will provide good information about the poorly observed region between 90 and 120 km. When the whole system comes on line, it will better enable coupling studies across these regions. By normalizing the relative densities to NCEP reanalysis or radiosonde densities below 30 km, the densities will become absolute all the way up to 120 km. By adding these new observations to those from the original data set, we will continue to examine temperature trends in the mesosphere. The upgrade is based on increasing the telescope collecting area to almost 5 m2 and increasing the 532 nm laser power to 42 W at 30 Hz. The combined effect is a 70 times increase in sensitivity. This increase enables us to go higher. It will also enable us to go lower by making Raman observations possible in the stratosphere, which will allow us to untangle the Rayleigh and Mie returns. Initial observations are approaching 120 km. These observations show significant temperature differences at the highest altitudes when compared to the MSISe00 empirical model.

Wickwar, V. B.; Sox, L.; Heron, J. P.; Emerick, M. T.

2013-12-01

242

Midlatitude cirrus classification at Rome Tor Vergata through a multichannel Raman-Mie-Rayleigh lidar  

NASA Astrophysics Data System (ADS)

A methodology to identify and characterize cirrus clouds has been developed and applied to the multichannel-multiwavelength Rayleigh-Mie-Raman (RMR) lidar in Rome Tor Vergata (RTV). A set of 167 cirrus cases, defined on the basis of quasi-stationary temporal period conditions, has been selected in a data set consisting of about 500 h of nighttime lidar sessions acquired between February 2007 and April 2010. The derived lidar parameters (effective height, geometrical and optical thickness and mean back-scattering ratio) and the cirrus mid-height temperature (estimated from the radiosonde data of Pratica di Mare, WMO, World Meteorological Organization, site no. 16245) of this sample have been analyzed by the means of a clustering multivariate analysis. This approach identified four cirrus classes above the RTV site: two thin cirrus clusters in mid- and upper troposphere and two thick cirrus clusters in mid-upper troposphere. These results, which are very similar to those derived through the same approach at the lidar site of the Observatoire de Haute-Provence (OHP), allows characterization of cirrus clouds over the RTV site and attests to the robustness of such classification. To acquire some indications about the cirrus generation methods for the different classes, analyses of the extinction-to-backscatter ratio (lidar ratio, LReff, in terms of frequency distribution functions and dependencies on the mid-height cirrus temperature, have been performed. A preliminary study relating some meteorological parameters (e.g., relative humidity, wind components) to cirrus clusters has also been conducted. The RTV cirrus results, recomputed through the cirrus classification by Sassen and Cho (1992), show good agreement with other midlatitude lidar cirrus observations for the relative occurrence of subvisible (SVC), thin and opaque cirrus classes (10%, 49% and 41%, respectively). The overall mean value of cirrus optical depth is 0.37 ± 0.18, while most retrieved LReff values range between 10-60 sr, and the estimated mean value is 31 ± 15 sr, similar to LR values of lower latitude cirrus measurements. The obtained results are consistent with previous studies conducted with different systems and confirm that cirrus classification based on a statistical approach seems to be a good tool both to validate the height-resolved cirrus fields calculated by models and to investigate the key processes governing cirrus formation and evolution. However, the lidar ratio and optical depth analyses are affected by some uncertainties (e.g., lidar error noise, multiple scattering effects, supercooled water clouds) that reduce the confidence of the results. Future studies are needed to improve the characterization of the cirrus optical properties and, thus, the determination of their radiative impact.

Dionisi, D.; Keckhut, P.; Liberti, G. L.; Cardillo, F.; Congeduti, F.

2013-12-01

243

Airborne High Spectral Resolution Lidar Aerosol Measurements during MILAGRO and TEXAQS/GOMACCS  

NASA Technical Reports Server (NTRS)

Two1 field experiments conducted during 2006 provided opportunities to investigate the variability of aerosol properties near cities and the impacts of these aerosols on air quality and radiative transfer. The Megacity Initiative: Local and Global Research Observations (MILAGRO) /Megacity Aerosol Experiment in Mexico City (MAX-MEX)/Intercontinental Chemical Transport Experiment-B (INTEX-B) joint experiment conducted during March 2006 investigated the evolution and transport of pollution from Mexico City. The Texas Air Quality Study (TEXAQS)/Gulf of Mexico Atmospheric Composition and Climate Study (GoMACCS) (http://www.al.noaa.gov/2006/) conducted during August and September 2006 investigated climate and air quality in the Houston/Gulf of Mexico region. During both missions, the new NASA Langley airborne High Spectral Resolution Lidar (HSRL) was deployed on the NASA Langley B200 King Air aircraft and measured profiles of aerosol extinction, backscattering, and depolarization to: 1) characterize the spatial and vertical distributions of aerosols, 2) quantify aerosol extinction and optical thickness contributed by various aerosol types, 3) investigate aerosol variability near clouds, 4) evaluate model simulations of aerosol transport, and 5) assess aerosol optical properties derived from a combination of surface, airborne, and satellite measurements.

Ferrare, Richard; Hostetler, Chris; Hair, John; Cook Anthony; Harper, David; Burton, Sharon; Clayton, Marian; Clarke, Antony; Russell, Phil; Redemann, Jens

2007-01-01

244

Backscatter Modeling at 2.1 Micron Wavelength for Space-Based and Airborne Lidars Using Aerosol Physico-Chemical and Lidar Datasets  

NASA Technical Reports Server (NTRS)

Space-based and airborne coherent Doppler lidars designed for measuring global tropospheric wind profiles in cloud-free air rely on backscatter, beta from aerosols acting as passive wind tracers. Aerosol beta distribution in the vertical can vary over as much as 5-6 orders of magnitude. Thus, the design of a wave length-specific, space-borne or airborne lidar must account for the magnitude of 8 in the region or features of interest. The SPAce Readiness Coherent Lidar Experiment under development by the National Aeronautics and Space Administration (NASA) and scheduled for launch on the Space Shuttle in 2001, will demonstrate wind measurements from space using a solid-state 2 micrometer coherent Doppler lidar. Consequently, there is a critical need to understand variability of aerosol beta at 2.1 micrometers, to evaluate signal detection under varying aerosol loading conditions. Although few direct measurements of beta at 2.1 micrometers exist, extensive datasets, including climatologies in widely-separated locations, do exist for other wavelengths based on CO2 and Nd:YAG lidars. Datasets also exist for the associated microphysical and chemical properties. An example of a multi-parametric dataset is that of the NASA GLObal Backscatter Experiment (GLOBE) in 1990 in which aerosol chemistry and size distributions were measured concurrently with multi-wavelength lidar backscatter observations. More recently, continuous-wave (CW) lidar backscatter measurements at mid-infrared wavelengths have been made during the Multicenter Airborne Coherent Atmospheric Wind Sensor (MACAWS) experiment in 1995. Using Lorenz-Mie theory, these datasets have been used to develop a method to convert lidar backscatter to the 2.1 micrometer wavelength. This paper presents comparison of modeled backscatter at wavelengths for which backscatter measurements exist including converted beta (sub 2.1).

Srivastava, V.; Rothermel, J.; Jarzembski, M. A.; Clarke, A. D.; Cutten, D. R.; Bowdle, D. A.; Spinhirne, J. D.; Menzies, R. T.

1999-01-01

245

Global Monitoring of Clouds and Aerosols Using a Network of Micro-Pulse Lidar Systems  

NASA Technical Reports Server (NTRS)

Long-term global radiation programs, such as AERONET and BSRN, have shown success in monitoring column averaged cloud and aerosol optical properties. Little attention has been focused on global measurements of vertically resolved optical properties. Lidar systems are the preferred instrument for such measurements. However, global usage of lidar systems has not been achieved because of limits imposed by older systems that were large, expensive, and logistically difficult to use in the field. Small, eye-safe, and autonomous lidar systems are now currently available and overcome problems associated with older systems. The first such lidar to be developed is the Micro-pulse lidar System (MPL). The MPL has proven to be useful in the field because it can be automated, runs continuously (day and night), is eye-safe, can easily be transported and set up, and has a small field-of-view which removes multiple scattering concerns. We have developed successful protocols to operate and calibrate MPL systems. We have also developed a data analysis algorithm that produces data products such as cloud and aerosol layer heights, optical depths, extinction profiles, and the extinction-backscatter ratio. The algorithm minimizes the use of a priori assumptions and also produces error bars for all data products. Here we present an overview of our MPL protocols and data analysis techniques. We also discuss the ongoing construction of a global MPL network in conjunction with the AERONET program. Finally, we present some early results from the MPL network.

Welton, Ellsworth J.; Campbell, James R.; Spinhirne, James D.; Scott, V. Stanley

2000-01-01

246

The atmospheric aerosol dynamics on Lidar and Sunphotometer data over Yakutsk  

NASA Astrophysics Data System (ADS)

The lidar and sunphotometer investigations of atmospheric aerosol layers vertical structure and dynamics have been carried out in Yakutsk (62N). Also the season and annual variations of the total atmospheric aerosol and water vapor concentration near Yakutsk have been carried out and the main features are developed. The atmosphere is cleaner on aerosol composition on fall and winter periods, but spring and summer period is differed by maximally hazing and variability of the aerosol optical depth. The investigation of seasonal feature of water vapor concentration in the atmosphere for 2004-2006 years showed an expected view of the seasonal distribution with maximum in the summer season, because of high activity of the lower atmosphere in summer and more intensive evaporation in the warm period. Some results on investigation of the influence of the solar corpuscular and geomagnetic activity on aerosol composition of atmosphere on the subauroral latitudes are discussed.

Nikolashkin, Semyen; Timofeeva, Galina; Sakerin, Sergey; Titov, Semyen; Marichev, Valery

247

Advances In Global Aerosol Modeling Applications Through Assimilation of Satellite-Based Lidar Measurements  

NASA Astrophysics Data System (ADS)

Modeling the instantaneous three-dimensional aerosol field and its downwind transport represents an endeavor with many practical benefits foreseeable to air quality, aviation, military and science agencies. The recent proliferation of multi-spectral active and passive satellite-based instruments measuring aerosol physical properties has served as an opportunity to develop and refine the techniques necessary to make such numerical modeling applications possible. Spurred by high-resolution global mapping of aerosol source regions, and combined with novel multivariate data assimilation techniques designed to consider these new data streams, operational forecasts of visibility and aerosol optical depths are now available in near real-time1. Active satellite-based aerosol profiling, accomplished using lidar instruments, represents a critical element for accurate analysis and transport modeling. Aerosol source functions, alone, can be limited in representing the macrophysical structure of injection scenarios within a model. Two-dimensional variational (2D-VAR; x, y) assimilation of aerosol optical depth from passive satellite observations significantly improves the analysis of the initial state. However, this procedure can not fully compensate for any potential vertical redistribution of mass required at the innovation step. The expense of an inaccurate vertical analysis of aerosol structure is corresponding errors downwind, since trajectory paths within successive forecast runs will likely diverge with height. In this paper, the application of a newly-designed system for 3D-VAR (x,y,z) assimilation of vertical aerosol extinction profiles derived from elastic-scattering lidar measurements is described [Campbell et al., 2009]. Performance is evaluated for use with the U. S. Navy Aerosol Analysis and Prediction System (NAAPS) by assimilating NASA/CNES satellite-borne Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) 0.532 ?m measurements [Winker et al., 2009]. Inversion retrievals of aerosol extinction are performed for one-degree latitudinal averages of CALIOP backscatter signal (thus matching the horizontal resolution of NAAPS) by constraining total column transmission using the model estimate of AOD at the corresponding wavelength. As such, this system serves as a post-processing module predicated on newly-operational NAAPS aerosol analysis fields that feature 2D-VAR assimilation of NASA Moderate Resolution Infrared Spectroradiometer (MODIS) AOD observations [Zhang and Reid, 2006; Zhang et al., 2008]. We describe the influence of 3D-VAR assimilation on NAAPS analyses and forecasts by considering the physical evolution of Saharan dust plumes during their advection across the tropical Atlantic basin. Steps taken towards characterizing spatial covariance parameters that broaden the horizontal influence of information obtained along the limited lidar orbital swath are discussed. This latter context is critical when comparing the efficacy and impact of 3D-VAR assimilation with that of 2D-VAR procedures, which benefit from passive observations with a relatively wide field-of-view and, therefore, greater/more routine global coverage. With multiple satellite-lidar projects either pending launch or in design stages, including the dual ESA missions (AEOLUS and EarthCARE), we describe the potential impact of future 3D-VAR assimilation activities; both for NAAPS forecast capabilities, and the anticipated growth in aerosol transport modeling efforts at federal and cooperative global agencies worldwide. 1 http://www.nrlmry.navy.mil/aerosol/ References Campbell, J. R., J. S. Reid, D. L. Westphal, J. Zhang, E. J. Hyer, and E. J. Welton, CALIOP aerosol subset processing for global aerosol transport model data assimilation, in press, J. Selected Topics Appl. Earth Obs. Rem. Sens., December 2009. Winker, D. M., M. A. Vaughan, A. Omar, Y. Hu, K. A. Powell, Z. Liu, W. H. Hunt, and S. A. Young, Overview of the CALIPSO mission and CALIOP data processing algorithms, J. Atmos. Oceanic. Technol., 26, DOI:10.1175/2009JTECHA1281.1, 2009. Zhang,

Campbell, James; Hyer, Edward; Zhang, Jianglong; Reid, Jeffrey; Westphal, Douglas; Xian, Peng; Vaughan, Mark

2010-05-01

248

A three-beam aerosol backscatter correlation lidar for three-component wind profiling  

NASA Astrophysics Data System (ADS)

In this paper, we describe the development of a three-beam elastic lidar that utilizes aerosol backscatter correlation to measure three-component wind profiles for detecting and tracking aircraft wake vortices; turbulence intensity and wind shear profiles. High-resolution time-resolved wind information can currently be obtained with ultrasonic or hot-wire anemometers suitable for local point measurements, or with Doppler wind lidars that only measure line-of-sight wind speeds and have to be scanned over large measurement cone angles for obtaining three-component winds. By tracking the motion of aerosol structures along and between three near-parallel laser beams, our lidar obtains three-component wind speed profiles along the field of view (FOV) of the lidar beams. Our prototype lidar wind profiler (LWP) has three 8-inch transceiver modules placed in a near-parallel configuration on a two-axis pan-tilt scanner to measure winds up to 2km away. Passively q-switched near-infrared (1030nm) Yb:YAG lasers generate 12 - 18ns wide pulses at high repetition rate (about 10KHz) that are expanded and attenuated to eye-safe levels. Sensitive low noise detection is achieved even in daytime using a narrow FOV receiver, together with narrowband interference filters and single photoncounting Geiger-mode Si detectors. A multi-channel scaler retrieves the lidar return with 7.8ns bins (˜1.2m spatial resolution) and stores accumulated counts once every 50ms (20 profiles/sec). We adapted optical flow algorithms to obtain the movement of aerosol structures between the beams. The performance of our prototype LWP was validated using sonic anemometer measurements.

Radhakrishnan Mylapore, Anand; Schwemmer, Geary K.; Prasad, Coorg R.; Lee, Sangwoo; Achey, Alexander; Hwang, In Heon; Mehta, Nikhil; Yakshin, Mikhail; Novoselov, Konstantin; Prasad, Narasimha S.

2014-06-01

249

Remote Sensing of Wind Fields and Aerosol Distribution with Airborne Scanning Doppler Lidar  

NASA Technical Reports Server (NTRS)

The coherent Doppler laser radar (lidar), when operated from an airborne platform, is a unique tool for the study of atmospheric and surface processes and features. This is especially true for scientific objectives requiring measurements in optically-clear air, where other remote sensing technologies such as Doppler radar are typically at a disadvantage. The atmospheric lidar remote sensing groups of several US institutions, led by Marshall Space Flight Center, have developed an airborne coherent Doppler lidar capable of mapping the wind field and aerosol structure in three dimensions. The instrument consists of an eye-safe approx. 1 Joule/pulse lidar transceiver, telescope, scanner, inertial measurement unit, and flight computer system to orchestrate all subsystem functions and tasks. The scanner is capable of directing the expanded lidar beam in a variety of ways, in order to extract vertically-resolved wind fields. Horizontal resolution is approx. 1 km; vertical resolution is even finer. Winds are obtained by measuring backscattered, Doppler-shifted laser radiation from naturally-occurring aerosol particles (of order 1 micron diameter). Measurement coverage depends on aerosol spatial distribution and composition. Velocity accuracy has been verified to be approx. 1 meter per second. A variety of applications have been demonstrated during the three flight campaigns conducted during 1995-1998. Examples will be shown during the presentation. In 1995, boundary layer winds over the ocean were mapped with unprecedented resolution. In 1996, unique measurements were made of. flow over the complex terrain of the Aleutian Islands; interaction of the marine boundary layer jet with the California coastal mountain range; a weak dry line in Texas - New Mexico; the angular dependence of sea surface scattering; and in-flight radiometric calibration using the surface of White Sands National Monument. In 1998, the first measurements of eyewall and boundary layer winds within a hurricane were made with the airborne Doppler lidar. Potential applications and plans for improvement will also be described.

Rothermel, Jeffry; Cutten, Dean R.; Johnson, Steven C.; Jazembski, Maurice; Arnold, James E. (Technical Monitor)

2001-01-01

250

Arctic-Winter Climatology and Radiative Effects of Clouds and Aerosols Based on Lidar and Radar Measurements at PEARL  

E-print Network

Arctic-Winter Climatology and Radiative Effects of Clouds and Aerosols Based on Lidar and Radar Atmospheric Radiative Transfer (SBDART) code. Results on the climatology and radiative effects of clouds

Eloranta, Edwin W.

251

Optical autocovariance direct detection lidar for simultaneous wind, aerosol, and chemistry profiling from ground, air, and space platforms  

Microsoft Academic Search

Optical Autocovariance Wind Lidar (OAWL) is a new direct-detection interferometric Doppler lidar approach that inherently enables simultaneous acquisition of multiple-wavelength High Spectral Resolution Lidar calibrated aerosol profiles (OA-HSRL). Unlike other coherent and direct detection Doppler systems, the receiver is self referencing; no specific optical frequency lock is required between the receiver and transmitter. This property facilitates frequency-agile modalities such as

Christian J. Grund; James Howell; Robert Pierce; Michelle Stephens

2009-01-01

252

Tropospheric ozone and aerosols measured by airborne lidar during the 1988 Arctic boundary layer experiment  

NASA Technical Reports Server (NTRS)

Ozone (O3) and aerosol distributions were measured from an aircraft using a differential absorption lidar (DIAL) system as part of the 1988 NASA Global Tropospheric Experiment - Arctic Boundary Layer Experiment (ABLE-3A) to study the sources and sinks of gases and aerosols over the tundra regions of Alaska during the summer. The tropospheric O3 budget over the Arctic was found to be strongly influenced by stratospheric intrusions. Regions of low aerosol scattering and enhanced O3 mixing ratios were usually correlated with descending air from the upper troposphere or lower stratosphere. Several cases of continental polar air masses were examined during the experiment. The aerosol scattering associated with these air masses was very low, and the atmospheric distribution of aerosols was quite homogeneous for those air masses that had been transported over the ice for greater than or = 3 days. The transition in O3 and aerosol distributions from tundra to marine conditions was examined several times. The aerosol data clearly show an abrupt change in aerosol scattering properties within the mixed layer from lower values over the tundra to generally higher values over the water. The distinct differences in the heights of the mixed layers in the two regions was also readily apparent. Several cases of enhanced O3 were observed during ABLE-3 in conjunction with enhanced aerosol scattering in layers in the free atmosphere. Examples are presented of the large scale variations of O3 and aerosols observed with the airborne lidar system from near the surface to above the tropopause over the Arctic during ABLE-3.

Browell, Edward V.; Butler, Carolyn F.; Kooi, Susan A.

1991-01-01

253

Multiplicative decomposition concept for atmospheric lidar assessment  

NASA Astrophysics Data System (ADS)

In the present paper, we show application examples of united generalized methodology for atmospheric lidar assessment, which uses the dimensionless-parameterization as a core component. It is based on a series of our previous works where the problem of universal parameterization over many lidar technologies were described and analyzed from different points of view. The approach can be widely used to evaluate a broad range of lidar system capabilities for a variety of lidar remote sensing applications, as well as to serve as a basis for selection of appropriate lidar system parameters for a specific application. Such a methodology provides generalized, uniform and objective approach for the evaluation of a broad range of lidar types and systems (aerosol, Raman, DIAL), operating on different targets (backscatter or topographic) and can be used within the lidar community to compare different lidar instruments.

Agishev, Ravil; Gross, Barry; Comeron, Adolfo; Moshary, Fred; Ahmed, Samir; Gilerson, Alexander

2006-08-01

254

Developing a portable, autonomous aerosol backscatter lidar for network or remote operations  

NASA Astrophysics Data System (ADS)

Lidar has the ability to detect the complex vertical structure of the atmosphere and can therefore identify the existence and extent of aerosols with high spatial and temporal resolution, making it well-suited for understanding atmospheric dynamics and transport processes. Environment Canada has developed a portable, autonomous lidar system that can be monitored remotely and operate continuously except during precipitation events. The lidar, housed in a small trailer, simultaneously emits two wavelengths of laser light (1064 nm and 532 nm) at energies of approximately 150 mJ/pulse/wavelength and detects the backscatter signal at 1064 nm and both polarizations at 532 nm. For laser energies of this magnitude, the challenge resides in designing a system that meets the airspace safety requirements for autonomous operations. Through the combination of radar technology, beam divergence, laser cavity interlocks and using computer log files, this risk was mitigated. A Continuum Inlite small footprint laser is the backbone of the system because of three design criteria: requiring infrequent flash lamp changes compared to previous Nd:YAG Q-switch lasers, complete software control capability and a built-in laser energy monitoring system. A computer-controlled interface was designed to monitor the health of the system, adjust operational parameters and maintain a climate-controlled environment. Through an internet connection, it also transmitted the vital performance indicators and data stream to allow the lidar profile data for multiple instruments from near ground to 15 km, every 10 s, to be viewed, in near real-time via a website. The details of the system design and calibration will be discussed and the success of the instrument as tested within the framework of a national lidar network dubbed CORALNet (Canadian Operational Research Aerosol Lidar Network). In addition, the transport of a forest fire plume across the country will be shown as evidenced by the lidar network, HYSPLIT back trajectories, MODIS imagery and CALIPSO overpasses.

Strawbridge, K. B.

2012-11-01

255

Developing a portable, autonomous aerosol backscatter lidar for network or remote operations  

NASA Astrophysics Data System (ADS)

Lidar has the ability to detect the complex vertical structure of the atmosphere and can therefore identify the existence and extent of aerosols with high spatial and temporal resolution, making it well suited for understanding atmospheric dynamics and transport processes. Environment Canada has developed a portable, autonomous lidar system that can be monitored remotely and operated continuously except during precipitation events. The lidar, housed in a small trailer, simultaneously emits two wavelengths of laser light (1064 nm and 532 nm) at energies of approximately 150 mJ/pulse/wavelength and detects the backscatter signal at 1064 nm and both polarizations at 532 nm. For laser energies of this magnitude, the challenge resides in designing a system that meets the airspace safety requirements for autonomous operations. Through the combination of radar technology, beam divergence, laser cavity interlocks and using computer log files, this risk was mitigated. A Continuum Inlite small footprint laser is the backbone of the system because of three design criteria: requiring infrequent flash lamp changes compared to previous Nd : YAG Q-switch lasers, complete software control capability and a built-in laser energy monitoring system. A computer-controlled interface was designed to monitor the health of the system, adjust operational parameters and maintain a climate-controlled environment. Through an Internet connection, it also transmitted the vital performance indicators and data stream to allow the lidar profile data for multiple instruments from near ground to 15 km, every 10 s, to be viewed, in near real-time via a website. The details of the system design and calibration will be discussed and the success of the instrument as tested within the framework of a national lidar network dubbed CORALNet (Canadian Operational Research Aerosol Lidar Network). In addition, the transport of a forest fire plume across the country will be shown as evidenced by the lidar network, HYSPLIT back trajectories, MODIS imagery and CALIPSO overpasses.

Strawbridge, K. B.

2013-03-01

256

Detection of atmospheric aerosol flow using a transit-time lidar velocimeter.  

PubMed

A cross-correlation analysis of lidar echoes from an artificial tracer transported through two closely spaced atmospheric scattering volumes provides a remote measurement of the wind speed along the line joining the two volumes. A pulsed nitrogen transit-time lidar has been developed and used to make these measurements in real-time intervals of approximately 4 sec. The wind speed measurements are compared with conventional anemometer data. An extension of this technique to natural aerosol concentrations that exploits the laser wavelength dependence of the system SNR is discussed. PMID:20165507

Armstrong, R L; Mason, J B; Barber, T

1976-11-01

257

Aerosol Vertical Distributions from GOCART Model and Comparisons with CALIPSO and In-situ Airborne Lidar Data  

NASA Technical Reports Server (NTRS)

We will show the GOCART model simulated vertical profiles of aerosol extinction, composition, and the extinction-to-backscatter ratios (lidar ratio) at different geographical regions during 2006. These results will be compared with the air-borne HSRL lidar and CALIPSO data.

Chin, Mian; Yu, Hongbin; Diehl, Thomas

2008-01-01

258

23/9 dimensional anisotropic scaling of passive admixtures using lidar data of aerosols Marc Lilley and Shaun Lovejoy  

E-print Network

23/9 dimensional anisotropic scaling of passive admixtures using lidar data of aerosols Marc Lilley by using state-of-the-art high-powered lidar data. We examine simultaneous horizontal and vertical sections unified scaling model of the atmosphere and is consistent with observations of the horizontal wind. DOI

Long, Bernard

259

Anomalies in Sea Spray Aerosol Optical Properties Detected by NASA High Spectral Resolution Lidar  

NASA Astrophysics Data System (ADS)

Data from a NASA flight mission over the Azores Archipelago off the western coast of Africa are analyzed to identify anomalies in sea spray aerosol optical properties associated with ocean biological production. The weeklong flight campaign began October 11, 2012 and focused on the sampling of clean marine air with little contamination from other sources like African dust or continental pollution. The NASA High Spectral Resolution Lidar (HSRL) has a laser that emits a pulse at two wavelengths (0.532 and 1.064 ?m) and a receiver that measures the backscattered radiation as a function of altitude. From this instrument, three important optical properties relevant to our study are derived: the aerosol lidar ratio, color ratio, and depolarization ratio, analysis of which can give insight into aerosol type, size, and shape respectively. To analyze the optical properties of aerosols within the marine boundary layer, one needs to accurately predict the boundary layer height and the presence of clouds in the optical path of the HSRL. Therefore, this study first introduces a new cloud-screening algorithm and then applies a boundary layer detection algorithm to filter the aerosol sample. Our analysis for the cloud free regions revealed statistically significant anomalies in particle depolarization ratio (?>10%) that were well correlated with surface chlorophyll-a concentrations (R?0.5) detected by NASA's MODerate Imaging Spectroradiometer (MODIS). Other parameters such as the lidar ratio and color ratio that are influenced by the aerosol size distribution and physiochemical properties will also be discussed. This study suggests that HSRL is suitable for exploring the effects of ocean biological production on clean marine aerosol optical properties.

Dawson, K. W.; Meskhidze, N.; Hu, Y.

2013-12-01

260

High resolution Raman lidar measurements for the characterization of the water vapour inflow in the frame of the Hydrological Cycle in the Mediterranean Experiment  

NASA Astrophysics Data System (ADS)

The University of BASILicata Raman Lidar system (BASIL) was deployed in Candillargues (Southern France, Lat: 43°37' N, Long: 4° 4' E) in the frame of the Hydrological Cycle in the Mediterranean Experiment - HyMeX. Within this experiment a major field campaign (Special Observation Period 1-SOP1, September to November 2012) took place over the Northwestern Mediterranean Sea and its surrounding coastal regions in France, Italy and Spain, with a specific focus on the study of heavy precipitation and flash-flood events. During HyMeX-SOP1, BASIL operated between 5 September and 5 November 2012, collecting more than 600 hours of measurements, distributed over 51 measurement days and 19 intensive observation periods (IOPs). The major feature of BASIL is represented by its capability to perform high-resolution and accurate measurements of atmospheric temperature and water vapour, both in daytime and night-time, based on the application of the rotational and vibrational Raman lidar techniques in the UV (Di Girolamo et al., 2004, 2006, 2009). This makes it an ideal tool for the characterization of the water vapour inflow in Southern France, which is important piece of information to improve the comprehension and forecasting capabilities of heavy precipitations in the Northwestern Mediterranean basin. Preliminary measurements from this field deployment will be illustrated and discussed at the Conference. These measurements allow to monitor and characterize the marine atmospheric flow that transport moist and conditionaly unstable air towards the coasts, which is feeding into the HPE events in Southern France. Measurements from BASIL can also be used to better characterize Planetary Boundary Layer moisture transport mechanisms from the surface to deep-convection systems. Besides temperature and water vapour, BASIL also provides measurements of the particle (aerosol/cloud) backscattering coefficient at 355, 532 and 1064 nm, of the particle extinction coefficient at 355 and 532 nm and of particle depolarization at 355 and 532 nm. The simultaneous characterization of the three-dimensional fields of water vapour, temperature and aerosol/cloud have the potential to lead to a better comprehension of the life cycle of HPE events around the Mediterranean Basin and ultimately lead to an improvement of cloud microphysical parameterization in Numerical Weather Prediction (NWP) models. References Di Girolamo, P., R. Marchese, D. N. Whiteman, B. B. Demoz, 2004: Rotational Raman Lidar measurements of atmospheric temperature in the UV, Geophysical Research Letters, 31, L01106, doi:10.1029/2003GL018342. Di Girolamo, P., A. Behrendt, and V. Wulfmeyer, 2006:. Spaceborne profiling of atmospheric temperature and particle extinction with pure rotational Raman lidar and of relative humidity in combination with differential absorption lidar: performance simulations, Applied Optics, 45, No. 11, 2474-2494, doi:10.1364/AO.45.002474. Di Girolamo, P., D. Summa, R. Ferretti, 2009: Multiparameter Raman Lidar Measurements for the Characterization of a Dry Stratospheric Intrusion Event, Journal of Atmospheric and Oceanic Technology, 26, No. 9, pp. 1742-1762, doi:10.1175/2009JTECHA1253.1.

Di Girolamo, Paolo; Cacciani, Marco; Stelitano, Dario; Summa, Donato

2013-04-01

261

Backscatter and depolarization measurements of aerosolized biological simulants using a chamber lidar system  

NASA Astrophysics Data System (ADS)

To ensure agent optical cross sections are well understood from the UV to the LWIR, volume integrated measurements of aerosolized agent material at a few key wavelengths is required to validate existing simulations. Ultimately these simulations will be used to assess the detection performance of various classes of lidar technology spanning the entire range of the optical spectrum. The present work demonstrates an optical measurement architecture based on lidar allowing the measurement of backscatter and depolarization ratio from biological aerosols released in a refereed, 1-m cubic chamber. During 2009, various upgrades have been made to the chamber LIDAR system, which operates at 1.064 ?m with sub nanosecond pulses at a 120 Hz repetition rate. The first build of the system demonstrated a sensitivity of aerosolized Bacillus atrophaeus (BG) on the order of 5×105 ppl with 1 GHz InGaAs detectors. To increase the sensitivity and reduce noise, the InGaAs detectors were replaced with larger-area silicon avalanche photodiodes for the second build of the system. In addition, computer controlled step variable neutral density filters are now incorporated to facilitate calibrating the system for absolute back-scatter measurements. Calibrated hard target measurements will be combined with data from the ground truth instruments for cross-section determination of the material aerosolized in the chamber. Measured results are compared to theoretical simulations of cross-sections.

Brown, David M.; Thrush, Evan P.; Thomas, Michael E.; Santarpia, Josh; Quizon, Jason; Carter, Christopher C.

2010-04-01

262

Towards quantifying mesoscale flows in the troposphere using Raman lidar and sondes  

SciTech Connect

Water vapor plays an important role in the energetics of the boundary layer processes which in turn play a key role in regulating regional and global climate. It plays a primary role in Earth`s hydrological cycle, in radiation balance as a direct absorber of infrared radiation, and in atmospheric circulation as a latent heat energy source as well as in determining cloud development and atmospheric stability. Water vapor concentration, expressed as a mass mixing ratio, is conserved in all meteorological processes except condensation and evaporation. This property makes it an ideal choice for studying many of the atmosphere`s dynamic features. Raman scattering measurements from lidar also allow retrieval of water vapor mixing ratio profiles at high temporal and vertical resolution. Raman lidars sense water vapor to altitudes not achievable with towers and surface systems, sample the atmosphere at much higher temporal resolution than radiosondes or satellites, and do not require strong vertical gradients or turbulent fluctuations in temperature that is required by acoustic sounders and radars. Analysis of highly resolved water vapor profiles are used here to characterize two important mesoscale flows: thunderstorm outflows and a cold front passage.

Demoz, B.; Evans, K. [Univ. of Maryland Baltimore County, Baltimore, MD (United States); Starr, D. [NASA, Greenbelt, MD (United States). Goddard Space Flight Center] [and others

1998-03-01

263

High spectral resolution lidar for measuring aerosol and atmospheric state parameters using an iodine vapor filter at 532 nm  

SciTech Connect

Measurements of vertical profiles of aerosol optical properties and atmospheric temperatures are of considerable importance to atmospheric physics. It is therefore one of the principal goals of lidar measurements in the troposphere to measure directly the backscatter ratio and temperature profiles, thereby determining all relevant vertical profiles of aerosol optical properties and state variables of a troposphere in hydrostatic and local thermal equilibrium. A high spectral resolution lidar (HSRL), with the use of atomic or molecular vapor filters, can spectrally separate molecular and aerosol scattering return signals to allow measurements of vertical aerosol properties and temperature profiles. The authors report progress in developing a high spectral resolution lidar system that measures vertical profiles of atmospheric temperature and aerosol optical properties using an iodine molecular vapor filter at a transmission wavelength of 532 nm.

Hair, J.; Caldwell, L.M.; Krueger, D.A.; She, C.Y. [Colorado State Univ., Fort Collins, CO (United States). Physics Dept.

1996-12-31

264

Using Airborne High Spectral Resolution Lidar Data to Evaluate Combined Active Plus Passive Retrievals of Aerosol Extinction Profiles  

NASA Technical Reports Server (NTRS)

We derive aerosol extinction profiles from airborne and space-based lidar backscatter signals by constraining the retrieval with column aerosol optical thickness (AOT), with no need to rely on assumptions about aerosol type or lidar ratio. The backscatter data were acquired by the NASA Langley Research Center airborne High Spectral Resolution Lidar (HSRL) and by the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) instrument on the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite. The HSRL also simultaneously measures aerosol extinction coefficients independently using the high spectral resolution lidar technique, thereby providing an ideal data set for evaluating the retrieval. We retrieve aerosol extinction profiles from both HSRL and CALIOP attenuated backscatter data constrained with HSRL, Moderate-Resolution Imaging Spectroradiometer (MODIS), and Multiangle Imaging Spectroradiometer column AOT. The resulting profiles are compared with the aerosol extinction measured by HSRL. Retrievals are limited to cases where the column aerosol thickness is greater than 0.2 over land and 0.15 over water. In the case of large AOT, the results using the Aqua MODIS constraint over water are poorer than Aqua MODIS over land or Terra MODIS. The poorer results relate to an apparent bias in Aqua MODIS AOT over water observed in August 2007. This apparent bias is still under investigation. Finally, aerosol extinction coefficients are derived from CALIPSO backscatter data using AOT from Aqua MODIS for 28 profiles over land and 9 over water. They agree with coincident measurements by the airborne HSRL to within +/-0.016/km +/- 20% for at least two-thirds of land points and within +/-0.028/km +/- 20% for at least two-thirds of ocean points.

Burton, S. P.; Ferrare, R. A.; Hostetler, C. A.; Hair, J. W.; Kittaka, C.; Vaughn, M. A.; Remer, L. A.

2010-01-01

265

Evaluations of Thin Cirrus Contamination and Screening in Ground Aerosol Observations Using Collocated Lidar Systems  

NASA Technical Reports Server (NTRS)

Cirrus clouds, particularly sub visual high thin cirrus with low optical thickness, are difficult to be screened in operational aerosol retrieval algorithms. Collocated aerosol and cirrus observations from ground measurements, such as the Aerosol Robotic Network (AERONET) and the Micro-Pulse Lidar Network (MPLNET), provide us with an unprecedented opportunity to examine the susceptibility of operational aerosol products to thin cirrus contamination. Quality assured aerosol optical thickness (AOT) measurements were also tested against the CALIPSO vertical feature mask (VFM) and the MODIS-derived thin cirrus screening parameters for the purpose of evaluating thin cirrus contamination. Key results of this study include: (1) Quantitative evaluations of data uncertainties in AERONET AOT retrievals are conducted. Although AERONET cirrus screening schemes are successful in removing most cirrus contamination, strong residuals displaying strong spatial and seasonal variability still exist, particularly over thin cirrus prevalent regions during cirrus peak seasons, (2) Challenges in matching up different data for analysis are highlighted and corresponding solutions proposed, and (3) Estimation of the relative contributions from cirrus contamination to aerosol retrievals are discussed. The results are valuable for better understanding and further improving ground aerosol measurements that are critical for aerosol-related climate research.

Huang, Jingfeng; Hsu, N. Christina; Tsay, Si-Chee; Holben, Brent N.; Welton, Ellsworth J.; Smirnov, Alexander; Jeong, Myeong-Jae; Hansell, Richard A.; Berkoff, Timothy A.

2012-01-01

266

The Double Edge Aerosol and Molecular Techniques for Doppler Lidar Wind Measurement  

NASA Technical Reports Server (NTRS)

We have developed the theory for aerosol- and molecular-based lidar measurements of the wind using double edge versions of the edge technique. Aerosol-based wind measurements have been made at Goddard Space Flight Center and molecular-based wind measurements at the University of Geneva. We have demonstrated atmospheric measurements using these techniques for altitudes from 1 to more than 10 km. Measurement accuracies of better than 1.25 m/s have been obtained with integration times from 5 to 30 seconds. The measurements can be scaled to space and agree, within a factor of two, with satellite-based simulations of performance based on Poisson statistics.

Korb, C. Laurence; Flesia, Cristina

1998-01-01

267

Lidar and Balloon-Borne Cascade Impactor Measurements of Aerosols: A Case Study  

Microsoft Academic Search

Aerosol size distributions, elemental components, complex refractive indices, extinction profiles and extinction-to-backscatter ratios have been measured and inferred from balloon-borne cascade impactor and lidar observations made during a cooperative joint experiment conducted during the period 4–10 April, 1980 in Tucson, AZ. Size distributions obtained from quartz crystal microbalance (QCM) cascade impactor measurements at different heights (1 to 1000 m) and

J. A. Reagan; M. V. Apte; T. V. Bruhns; O. Youngbluth

1984-01-01

268

Airborne high spectral resolution lidar for measuring aerosol extinction and backscatter coefficients  

Microsoft Academic Search

An airborne high spectral resolution lidar (HSRL) based on an iodine absorption filter and a high-power frequency-doubled Nd:YAG laser has been developed to measure backscatter and extinction coefficients of aerosols and clouds. The instrument was operated aboard the Falcon 20 research aircraft of the German Aerospace Center (DLR) during the Saharan Mineral Dust Experiment in May-June 2006 to measure optical

Michael Esselborn; Martin Wirth; Andreas Fix; Matthias Tesche; Gerhard Ehret

2008-01-01

269

Airborne High Spectral Resolution Lidar Aerosol Measurements during CalNex and CARES  

Microsoft Academic Search

The NASA Langley Research Center (LaRC) airborne High Spectral Resolution Lidar (HSRL) on board the NASA B200 aircraft measured aerosol extinction (532 nm), backscatter (532 and 1064 nm) and depolarization (532 and 1064 nm) profiles during the 2010 CalNex and CARES field missions. During the CalNex deployment in May 2010, HSRL data were acquired during eight science flights that were

C. A. Hostetler; R. A. Ferrare; J. W. Hair; A. Cook; D. Harper; S. P. Burton; M. D. Obland; R. Rogers; C. F. Butler; A. J. Swanson

2010-01-01

270

Comparison of Summer and Winter California Central Valley Aerosol Distributions from Lidar and MODIS Measurements  

NASA Technical Reports Server (NTRS)

Aerosol distributions from two aircraft lidar campaigns conducted in the California Central Valley are compared in order to identify seasonal variations. Aircraft lidar flights were conducted in June 2003 and February 2007. While the ground PM(sub 2.5) concentration is highest in the winter, the aerosol optical depth measured from MODIS is highest in the summer. A seasonal comparison shows that PM(sub 2.5) in the winter can exceed summer PM(sub 2.5) by 55%, while summer AOD exceeds winter AOD by 43%. Higher temperatures and wildfires in the summer produce elevated aerosol layers that are detected by satellite measurements, but not surface particulate matter monitors. Temperature inversions, especially during the winter, contribute to higher PM(sub 2.5) measurements at the surface. Measurements of the boundary layer height from lidar instruments provide valuable information need to understand the relationship between satellite measurements of optical depth and in-situ measurements of PM(sub 2.5).

Lewis, Jasper; DeYoung, Russell; Ferrare, Richard; Chu, D. Allen

2010-01-01

271

Study of relationship between water-soluble Ca 2+ and lidar depolarization ratio for spring aerosol in the boundary layer  

Microsoft Academic Search

The backscattering ratio, depolarization ratio and water-soluble ions of aerosols inside the boundary layer were measured by a depolarization lidar and an in situ ion chromatography (IC) in the spring of 2004 and 2005. To study the relationship between depolarization and aerosol compositions, depolarization ratios were compared with mixing ratio of soluble ions like calcium, potassium, and sodium from surface

Wei-Nai Chen; Shih-Yu Chang; Charles C.-K. Chou; Yi-Wei Chen; Jen-Ping Chen

2007-01-01

272

Ruby lidar observations and trajectory analysis of stratospheric aerosols injected by the volcanic eruptions of El Chichon  

NASA Technical Reports Server (NTRS)

Large amounts of aerosol particles and gases were injected into the lower stratosphere by the violet volcanic eruptions of El Chichon on March 28, and April 3 and 4, 1982. Observational results obtained by a ruby lidar at Tsukuba (36.1 deg N, 140.1 deg E) are shown, and some points of latitude dispersion processes of aerosols are discussed.

Uchino, O.; Tabata, T.; Akita, I.; Okada, Y.; Naito, K.

1985-01-01

273

Using Airborne High Spectral Resolution Lidar Data to Evaluate Combined Active Plus Passive Retrievals of Aerosol Extinction Profiles  

NASA Technical Reports Server (NTRS)

Aerosol extinction profiles are derived from backscatter data by constraining the retrieval with column aerosol optical thickness (AOT), for example from coincident MODIS observations and without reliance on a priori assumptions about aerosol type or optical properties. The backscatter data were acquired with the NASA Langley High Spectral Resolution Lidar (HSRL). The HSRL also simultaneously measures extinction independently, thereby providing an ideal data set for evaluating the constrained retrieval of extinction from backscatter. We will show constrained extinction retrievals using various sources of column AOT, and examine comparisons with the HSRL extinction measurements and with a similar retrieval using data from the CALIOP lidar on the CALIPSO satellite.

Burton, S. P.; Ferrare, R. A.; Kittaka, C.; Hostetler, C. A.; Hair, J. W.; Obland, M. D.; Rogers, R. R.; Cook, A. L.; Haper, D. B.

2008-01-01

274

Combined retrievals of boreal forest fire aerosol properties with a polarimeter and lidar  

NASA Astrophysics Data System (ADS)

Absorbing aerosols play an important, but uncertain, role in the global climate. Much of this uncertainty is due to a lack of adequate aerosol measurements. While great strides have been made in observational capability in the previous years and decades, it has become increasingly apparent that this development must continue. Scanning polarimeters have been designed to help resolve this issue by making accurate, multi-spectral, multi-angle polarized observations. This work involves the use of the Research Scanning Polarimeter (RSP). The RSP was designed as the airborne prototype for the Aerosol Polarimetery Sensor (APS), which was due to be launched as part of the (ultimately failed) NASA Glory mission. Field observations with the RSP, however, have established that simultaneous retrievals of aerosol absorption and vertical distribution over bright land surfaces are quite uncertain. We test a merger of RSP and High Spectral Resolution Lidar (HSRL) data with observations of boreal forest fire smoke, collected during the Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS). During ARCTAS, the RSP and HSRL instruments were mounted on the same aircraft, and validation data were provided by instruments on an aircraft flying a coordinated flight pattern. We found that the lidar data did indeed improve aerosol retrievals using an optimal estimation method, although not primarily because of the contraints imposed on the aerosol vertical distribution. The more useful piece of information from the HSRL was the total column aerosol optical depth, which was used to select the initial value (optimization starting point) of the aerosol number concentration. When ground based sun photometer network climatologies of number concentration were used as an initial value, we found that roughly half of the retrievals had unrealistic sizes and imaginary indices, even though the retrieved spectral optical depths agreed within uncertainties to independent observations. The convergence to an unrealistic local minimum by the optimal estimator is related to the relatively low sensitivity to particles smaller than 0.1 (?m) at large optical thicknesses. Thus, optimization algorithms used for operational aerosol retrievals of the fine mode size distribution, when the total optical depth is large, will require initial values generated from table look-ups that exclude unrealistic size/complex index mixtures. External constraints from lidar on initial values used in the optimal estimation methods will also be valuable in reducing the likelihood of obtaining spurious retrievals.

Knobelspiesse, K.; Cairns, B.; Ottaviani, M.; Ferrare, R.; Hair, J.; Hostetler, C.; Obland, M.; Rogers, R.; Redemann, J.; Shinozuka, Y.; Clarke, A.; Freitag, S.; Howell, S.; Kapustin, V.; McNaughton, C.

2011-07-01

275

Combined Retrievals of Boreal Forest Fire Aerosol Properties with a Polarimeter and Lidar  

NASA Technical Reports Server (NTRS)

Absorbing aerosols play an important, but uncertain, role in the global climate. Much of this uncertainty is due to a lack of adequate aerosol measurements. While great strides have been made in observational capability in the previous years and decades, it has become increasingly apparent that this development must continue. Scanning polarimeters have been designed to help resolve this issue by making accurate, multi-spectral, multi-angle polarized observations. This work involves the use of the Research Scanning Polarimeter (RSP). The RSP was designed as the airborne prototype for the Aerosol Polarimetery Sensor (APS), which was due to be launched as part of the (ultimately failed) NASA Glory mission. Field observations with the RSP, however, have established that simultaneous retrievals of aerosol absorption and vertical distribution over bright land surfaces are quite uncertain. We test a merger of RSP and High Spectral Resolution Lidar (HSRL) data with observations of boreal forest fire smoke, collected during the Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS). During ARCTAS, the RSP and HSRL instruments were mounted on the same aircraft, and validation data were provided by instruments on an aircraft flying a coordinated flight pattern. We found that the lidar data did indeed improve aerosol retrievals using an optimal estimation method, although not primarily because of the constraints imposed on the aerosol vertical distribution. The more useful piece of information from the HSRL was the total column aerosol optical depth, which was used to select the initial value (optimization starting point) of the aerosol number concentration. When ground based sun photometer network climatologies of number concentration were used as an initial value, we found that roughly half of the retrievals had unrealistic sizes and imaginary indices, even though the retrieved spectral optical depths agreed within uncertainties to independent observations. The convergence to an unrealistic local minimum by the optimal estimator is related to the relatively low sensitivity to particles smaller than 0.1 ( m) at large optical thicknesses. Thus, optimization algorithms used for operational aerosol retrievals of the fine mode size distribution, when the total optical depth is large, will require initial values generated from table look-ups that exclude unrealistic size/complex index mixtures. External constraints from lidar on initial values used in the optimal estimation methods will also be valuable in reducing the likelihood of obtaining spurious retrievals.

Knobelspiesse, K.; Cairns, B.; Ottaviani, M.; Ferrare, R.; Haire, J.; Hostetler, C.; Obland, M.; Rogers, R.; Redemann, J.; Shinozuka, Y.; Clarke, A.; Freitag, S.; Howell, S.; Kapustin, V.; McNaughton, C.

2011-01-01

276

Benefit of depolarization ratio at ? = 1064 nm for the retrieval of the aerosol microphysics from lidar measurements  

NASA Astrophysics Data System (ADS)

A better quantification of aerosol microphysical and optical properties is required to improve the modelling of aerosol effects on weather and climate. This task is methodologically demanding due to the huge diversity of aerosol composition and of their shape and size distribution, and due to the complexity of the relation between the microphysical and optical properties. Lidar remote sensing is a valuable tool to gain spatially and temporally resolved information on aerosol properties. Advanced lidar systems provide sufficient information on the aerosol optical properties for the retrieval of important aerosol microphysical properties. Recently, the mass concentration of transported volcanic ash, which is relevant for the flight safety of airplanes, was retrieved from measurements of such lidar systems in Southern Germany. The relative uncertainty of the retrieved mass concentration was on the order of ±50%. The present study investigates improvements of the retrieval accuracy when the capability of measuring the linear depolarization ratio at 1064 nm is added to the lidar setup. The lidar setups under investigation are based on the setup of MULIS and POLIS of the LMU in Munich which measure the linear depolarization ratio at 355 nm and 532 nm with high accuracy. By comparing results of retrievals applied to simulated lidar measurements with and without the depolarization at 1064 nm it is found that the availability of 1064 nm depolarization measurements reduces the uncertainty of the retrieved mass concentration and effective particle size by a factor of about 2-3. This significant improvement in accuracy is the result of the increased sensitivity of the lidar setup to larger particles. However, the retrieval of the single scattering albedo, which is relevant for the radiative transfer in aerosol layers, does hardly benefit from the availability of 1064 nm depolarization measurements.

Gasteiger, J.; Freudenthaler, V.

2014-05-01

277

Design of an airborne lidar for stratospheric aerosol measurements  

NASA Technical Reports Server (NTRS)

A modular, multiple-telescope receiving concept is developed to gain a relatively large receiver collection aperture without requiring extensive modifications to the aircraft. This concept, together with the choice of a specific photodetector, signal processing, and data recording system capable of maintaining approximately 1% precision over the required large signal amplitude range, is found to be common to all of the options. It is recommended that development of the lidar begin by more detailed definition of solutions to these important common signal detection and recording problems.

Evans, W. E.

1977-01-01

278

LABVIEW graphical user interface for precision multichannel alignment of Raman lidar at Jet Propulsion Laboratory, Table Mountain Facility.  

PubMed

The Jet Propulsion Laboratory operates lidar systems at Table Mountain Facility (TMF), California (34.4 degrees N, 117.7 degrees W) and Mauna Loa Observatory, Hawaii (19.5 degrees N, 155.6 degrees W) under the framework of the Network for the Detection of Atmospheric Composition Change. To complement these systems a new Raman lidar has been developed at TMF with particular attention given to optimizing water vapor profile measurements up to the tropopause and lower stratosphere. The lidar has been designed for accuracies of 5% up to 12 km in the free troposphere and a detection capability of <5 ppmv. One important feature of the lidar is a precision alignment system using range resolved data from eight Licel transient recorders, allowing fully configurable alignment via a LABVIEW/C++ graphical user interface (GUI). This allows the lidar to be aligned on any channel while simultaneously displaying signals from other channels at configurable altitude/bin combinations. The general lidar instrumental setup and the details of the alignment control system, data acquisition, and GUI alignment software are described. Preliminary validation results using radiosonde and lidar intercomparisons are briefly presented. PMID:19044439

Aspey, R A; McDermid, I S; Leblanc, T; Howe, J W; Walsh, T D

2008-09-01

279

LABVIEW graphical user interface for precision multichannel alignment of Raman lidar at Jet Propulsion Laboratory, Table Mountain Facility  

NASA Astrophysics Data System (ADS)

The Jet Propulsion Laboratory operates lidar systems at Table Mountain Facility (TMF), California (34.4°N, 117.7°W) and Mauna Loa Observatory, Hawaii (19.5°N, 155.6°W) under the framework of the Network for the Detection of Atmospheric Composition Change. To complement these systems a new Raman lidar has been developed at TMF with particular attention given to optimizing water vapor profile measurements up to the tropopause and lower stratosphere. The lidar has been designed for accuracies of 5% up to 12 km in the free troposphere and a detection capability of <5 ppmv. One important feature of the lidar is a precision alignment system using range resolved data from eight Licel transient recorders, allowing fully configurable alignment via a LABVIEW/C++ graphical user interface (GUI). This allows the lidar to be aligned on any channel while simultaneously displaying signals from other channels at configurable altitude/bin combinations. The general lidar instrumental setup and the details of the alignment control system, data acquisition, and GUI alignment software are described. Preliminary validation results using radiosonde and lidar intercomparisons are briefly presented.

Aspey, R. A.; McDermid, I. S.; Leblanc, T.; Howe, J. W.; Walsh, T. D.

2008-09-01

280

High spectral resolution lidar to measure optical scattering properties of atmospheric aerosols. II - Calibration and data analysis  

NASA Technical Reports Server (NTRS)

The high spectral resolution lidar (HSRL) measures optical properties of atmospheric aerosols by interferometically separating the elastic aerosol backscatter from the Doppler broadened molecular contribution. Calibration and data analysis procedures developed for the HSRL are described. Data obtained during flight evaluation testing of the HSRL system are presented with estimates of uncertainties due to instrument calibration. HSRL measurements of the aerosol scattering cross section are compared with in situ integrating nephelometer measurements.

Sroga, J. T.; Eloranta, E. W.; Roesler, F. L.; Shipley, S. T.; Tryon, P. J.

1983-01-01

281

High spectral resolution lidar to measure optical scattering properties of atmospheric aerosols. 2: calibration and data analysis.  

PubMed

The high spectral resolution lidar (HSRL) measures optical properties of atmospheric aerosols by interferometrically separating the elastic aerosol backscatter from the Doppler broadened molecular contribution. Calibration and data analysis procedures developed for the HSRL are described. Data obtained during flight evaluation testing of the HSRL system are presented with estimates of uncertainties due to instrument calibration. HSRL measurements of the aerosol scattering cross section are compared with in situ integrating nephelometer measurements. PMID:18200257

Sroga, J T; Eloranta, E W; Shipley, S T; Roesler, F L; Tryon, P J

1983-12-01

282

Validation of the Lidar In-Space Technology Experiment: stratospheric temperature and aerosol measurements  

NASA Astrophysics Data System (ADS)

The Lidar In-Space Technology Experiment (LITE) was flown on STS-64 in September 1994. The LITE employed a Nd:YAG laser operating at 1064, 532, and 355 nm to study the Earth s lower atmosphere. In this paper we investigate the nighttime stratospheric aerosol and temperature measurements derived from the 532- and 355-nm channels. The observations are compared with lidar observations obtained at Arecibo Observatory, Puerto Rico, and Starfire Optical Range, New Mexico, and with balloonsondes launched from the San Juan and Albuquerque airports. The backscatter ratios derived from the LITE and Arecibo data between 15 and 30 km differ by less than 5 . The Angstrom coefficients of the stratospheric aerosols derived from the 532- and 355-nm LITE channels exhibited only slight variation in altitude. The mean value between 15 and 30 km derived from three different orbital segments at approximately 20 N and 35 N was 1.7. The mean standard deviation was approximately 0.3. Temperature profiles were derived from the LITE data by correcting the 355-nm channel for aerosol scattering with the 532-nm signal and an assumed Angstrom coefficient. The rms differences between the corrected profiles and the balloonsonde data were as low as 2 K in the 15 30-km height range. The results were not particularly sensitive to the choice of the Angstrom coefficient and suggest that accurate temperature profiles can be derived from the LITE data in the upper troposphere and lower stratosphere provided that the aerosol loading is light.

Gu, Yiyun Y.; Gardner, Chester S.; Castleberg, Paul A.; Papen, George C.; Kelley, Michael C.

1997-07-01

283

Modeling LIDAR Detection of Biological Aerosols to Determine Optimum Implementation Strategy  

SciTech Connect

This report summarizes work performed for a larger multi-laboratory project named the Background Interferent Measurement and Standards project. While originally tasked to develop algorithms to optimize biological warfare agent detection using UV fluorescence LIDAR, the current uncertainties in the reported fluorescence profiles and cross sections the development of any meaningful models. It was decided that a better approach would be to model the wavelength-dependent elastic backscattering from a number of ambient background aerosol types, and compare this with that generated from representative sporulated and vegetative bacterial systems. Calculations in this report show that a 266, 355, 532 and 1064 nm elastic backscatter LIDAR experiment will allow an operator to immediately recognize when sulfate, VOC-based or road dust (silicate) aerosols are approaching, independent of humidity changes. It will be more difficult to distinguish soot aerosols from biological aerosols, or vegetative bacteria from sporulated bacteria. In these latter cases, the elastic scattering data will most likely have to be combined with UV fluorescence data to enable a more robust categorization.

Sheen, David M.; Aker, Pam M.

2007-09-19

284

Measurements of Aerosol Vertical Profiles and Optical Properties during INDOEX 1999 Using Micro-Pulse Lidars  

NASA Technical Reports Server (NTRS)

Micro-pulse lidar systems (MPL) were used to measure aerosol properties during the Indian Ocean Experiment (INDOEX) 1999 field phase. Measurements were made from two platforms: the NOAA ship RN Ronald H. Brown, and the Kaashidhoo Climate Observatory (KCO) in the Maldives. Sunphotometers were used to provide aerosol optical depths (AOD) needed to calibrate the MPL. This study focuses on the height distribution and optical properties (at 523 nm) of aerosols observed during the campaign. The height of the highest aerosols (top height) was calculated and found to be below 4 km for most of the cruise. The marine boundary layer (MBL) top was calculated and found to be less than 1 km. MPL results were combined with air mass trajectories, radiosonde profiles of temperature and humidity, and aerosol concentration and optical measurements. Humidity varied from approximately 80% near the surface to 50% near the top height during the entire cruise. The average value and standard deviation of aerosol optical parameters were determined for characteristic air mass regimes. Marine aerosols in the absence of any continental influence were found to have an AOD of 0.05 +/- 0.03, an extinction-to-backscatter ratio (S-ratio) of 33 +/- 6 sr, and peak extinction values around 0.05/km (near the MBL top). The marine results are shown to be in agreement with previously measured and expected values. Polluted marine areas over the Indian Ocean, influenced by continental aerosols, had AOD values in excess of 0.2, S-ratios well above 40 sr, and peak extinction values approximately 0.20/km (near the MBL top). The polluted marine results are shown to be similar to previously published values for continental aerosols. Comparisons between MPL derived extinction near the ship (75 m) and extinction calculated at ship-level using scattering measured by a nephelometer and absorption using a PSAP were conducted. The comparisons indicated that the MPL algorithm (using a constant S-ratio throughout the lower troposphere) calculates extinction near the surface in agreement with the ship-level measurements only when the MBL aerosols are well mixed with aerosols above. Finally, a review of the MPL extinction profiles showed that the model of aerosol vertical extinction developed during an earlier INDOEX field campaign (at the Maldives) did not correctly describe the true vertical distribution over the greater Indian Ocean region. Using the average extinction profile and AOD obtained during marine conditions, a new model of aerosol vertical extinction was determined for marine atmospheres over the Indian Ocean. A new model of aerosol vertical extinction for polluted marine atmospheres was also developed using the average extinction profile and AOD obtained during marine conditions influenced by continental aerosols.

Welton, Ellsworth J.; Voss, Kenneth J.; Quinn, Patricia K.; Flatau, Piotr J.; Markowicz, Krzysztof; Campbell, James R.; Spinhirne, James D.; Gordon, Howard R.; Johnson, James E.; Starr, David OC. (Technical Monitor)

2001-01-01

285

Combined retrievals of boreal forest fire aerosol properties with a polarimeter and lidar  

NASA Astrophysics Data System (ADS)

Absorbing aerosols play an important, but uncertain, role in the global climate. Much of this uncertainty is due to a lack of adequate aerosol measurements. The Aerosol Polarimetery Sensor (APS), which is on the NASA Glory satellite scheduled for launch in the spring of 2011, is designed to help resolve this issue by making accurate, multi-spectral, multi-angle polarized observations. Field observations with the Research Scanning Polarimeter (RSP, the APS airborne prototype), however, have established that simultaneous retrievals of aerosol absorption and vertical distribution over bright land surfaces are quite uncertain. We test a merger of RSP and High Spectral Resolution Lidar (HSRL) data with observations of boreal forest fire smoke, collected during the Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS). During ARCTAS, the RSP and HSRL instruments were mounted on the same aircraft, and validation data were provided by instruments on an aircraft flying a coordinated flight pattern. We found that the lidar data did indeed improve aerosol retrievals using an optimal estimation method, although not primarily because of the contraints imposed on the aerosol vertical distribution. The more useful piece of information from the HSRL was the total column aerosol optical depth, which was used to select the initial value (optimization starting point) of the aerosol number concentration. When ground based sun photometer network climatologies of number concentration were used as an initial value, we found that roughly half of the retrievals had unrealistic sizes and imaginary indices, even though the retrieved spectral optical depths agreed within uncertainties to independent observations. The convergence to an unrealistic local minimum by the optimal estimator is related to the relatively low sensitivity to particles smaller than 0.1 µm at large optical thicknesses. Thus, optimization algorithms used for operational APS retrievals of the fine mode size distribution, when the total optical depth is large, will require initial values generated from table look-ups that exclude unrealistic size/complex index mixtures. External constraints from lidar on initial values used in the optimal estimation methods will also be valuable in reducing the likelihood of obtaining spurious retrievals.

Knobelspiesse, K.; Cairns, B.; Ottaviani, M.; Ferrare, R.; Hair, J.; Hostetler, C.; Obland, M.; Rogers, R.; Redemann, J.; Shinozuka, Y.; Clarke, A.; Freitag, S.; Howell, S.; Kapustin, V.; McNaughton, C.

2011-03-01

286

Optical Properties of Remote Ocean Aerosols As Measured by an Air-borne High Spectral Resolution Lidar  

NASA Astrophysics Data System (ADS)

A high spectral resolution lidar (HSRL) was operated aboard the National Science Foundation's (NSF) Gulfstream V (GV) aircraft as part of the Tropical Ocean tRoposphere Exchange of Reactive halogen species and Oxy-genated VOC (TORERO) field program. The HSRL makes calibrated measurements of the optical properties of atmospheric aerosols and clouds: backscatter cross section, depolarization ratio and extinction. The lidar can make these calibrated measurements of atmospheric aerosols and clouds at distances in excess of 20 km. During the TORERO field program the lidar was used to detect and measure the optical properties of aerosol layers above or below the aircraft. Examples of the real-time and post-flight data products available from the lidar will be shown include calibrated backscatter cross section, depolarization ratio, extinction and integrated optical depth. These calibrated data products from the lidar will be used by other investigators to enhance their data processing. Backscatter cross section image taken on 27 January 2012 as the aircraft was profiling the atmosphere and the lidar was being switched between zenith and nadir pointing. Backscatter cross section image taken on 3 February 2012 from an altitude near 14km with cirrus clouds at 18km and a stratospheric aerosol layer between 19km and 21km as observed from below.

Morley, B.; Spuler, S.; Vivekanandan, J.; Eloranta, E.

2012-12-01

287

Femtosecond Coherent Anti-Stokes Raman Spectroscopy (CARS) As Next Generation Nonlinear LIDAR Spectroscopy and Microscopy  

SciTech Connect

Nonlinear spectroscopy using coherent anti-Stokes Raman scattering and femtosecond laser pulses has been successfully developed as powerful tools for chemical analysis and biological imaging. Recent developments show promising possibilities of incorporating CARS into LIDAR system for remote detection of molecular species in airborne particles. The corresponding theory is being developed to describe nonlinear scattering of a mesoscopic particle composed of complex molecules by laser pulses with arbitrary shape and spectral content. Microscopic many-body transform theory is used to compute the third order susceptibility for CARS in molecules with known absorption spectrum and vibrational modes. The theory is combined with an integral scattering formula and Mie-Lorentz formulae, giving a rigorous formalism which provides powerful numerical experimentation of CARS spectra, particularly on the variations with the laser parameters and the direction of detection.

Ooi, C. H. Raymond [School of Engineering, Monash University, Jalan Lagoon Selatan, Bandar Sunway, 46150 Selangor DarulEhsan, Malaysia and Department of Physics, Korea University, Anam-dong, Seongbuk-gu, Seoul, 136-713 (Korea, Republic of)

2009-07-10

288

El Chichon aerosols in the stratosphere: Analyses of lidar data and calculations of radiation budget  

NASA Technical Reports Server (NTRS)

Lidar observation at Fukuoka has provided over four years the data of ElChichon aerosols in the stratosphere. Analyses of the data show that an enormous amount of volcanic aerosols has continuously decreased since the beginning of 1983 with significant fluctuations. These fluctuations reveal themselves as a seasonal variation of aerosol content with a maximum in winter-spring and a minimum in summer. The vertical structure of the aerosol layer also shows the seasonal variation. Although the height of a peak around 18 km in the vertical profile of scattering ratio show littel variation, the higher second peak appears frequently from late fall and the lower third peak from late winter to late spring just as two and more tropopauses appear in these periods. The mechanism which causes the seasonal variation will be discussed in terms of the transport by the atmoshperic circulation and the removal through the tropopause gap. Radiation budget in the atmosphere was calculated taking into account the large amount of aerosols observed in the early stages of the El Chichon event. The heating rate of the atmosphere is more than 1 K in the bottom region of the stratosphere even in the nighttime. The possible effect of the volcanic aerosols on the other geophysical phenomena will be discussed using the calculated values of the heating rate.

Fujiwara, M.; Akiyoshi, H.; Otsuka, N.

1986-01-01

289

Lidar and in-situ observation of aerosol layers above the top of tropical convection  

NASA Astrophysics Data System (ADS)

We present evidences for overshooting aerosol layers, emerging from the top of a strong tropical convection. Such overshooting aerosol layers penetrate the stratosphere and may deposit ice particles at altitudes reaching 420 K potential temperature. In such way, these convective events may have a hydrating effect on the lower tropical stratosphere, whereas there were no signs of convectively induced dehydration. The evidences for overshooting layers are based on lidar and in-situ detection of ice particles in the tropical stratosphere found during the high-altitude research aircraft "Geophysica" campaigns TROCCINOX and SCOUT-O3. The detection of the scattering ratio above the top of the convection and below the flight level of the aircraft was performed by a backscatter lidar, with correction of the overlap function. This correction is based on the detection of the pure molecular backscatter. The lidar probes downward from the flight level the top of the convection and the overshooting layers. The particle number and particle total surface at the flight level are detected by a Forward Scattering Spectrometer Probe FSSP-100.

Mitev, V.; Matthey, R.; Corti, T.; Peter, T.; Martucci, G.; de Reus, M.; Borrmann, S.; Sitnikov, N.; Makarov, V.

2009-04-01

290

Miniature and Cost-Effective Remote Raman, Fluorescence, and Lidar Multi-Spectral Instrument for Characterization of Planetary Surfaces and Atmosphere from Robotic Platform  

NASA Astrophysics Data System (ADS)

The objective of this study is to develop a remote Raman-Fluorescence spectroscopy and Lidar multi-sensor instrument capable of investigation and identification of minerals, organics, and biogenic materials, as well as atmospheric studies of Mars.

Abedin, M. N.; Bradley, A. T.; Ismail, S.; Sharma, S. K.; Lucey, P. G.; Misra, A. K.; Sandford, S. P.

2012-06-01

291

A High Spectral Resolution Lidar at 532 nm for simultaneous measurement of atmospheric state and aerosol profiles using iodine vapor filters  

Microsoft Academic Search

This dissertation presents a High Spectral Resolution Lidar (HSRL) to simultaneously measure vertical profiles of atmospheric temperature, pressure, aerosol to molecular backscatter ratio, and aerosol extinction coefficient. The lidar uses a narrow band pulsed laser source operated at 532 nm and iodine vapor filters are used as narrowband notch filters in the detection system to spectrally separate the Doppler broadened

Johnathan Wayne Hair

1998-01-01

292

Evaluating Global Aerosol Models and Aerosol and Water Vapor Properties Near Clouds  

SciTech Connect

The 'Evaluating Global Aerosol Models and Aerosol and Water Vapor Properties Near Clouds' project focused extensively on the analysis and utilization of water vapor and aerosol profiles derived from the ARM Raman lidar at the Southern Great Plains ARM site. A wide range of different tasks were performed during this project, all of which improved quality of the data products derived from the lidar or advanced the understanding of atmospheric processes over the site. These activities included: upgrading the Raman lidar to improve its sensitivity; participating in field experiments to validate the lidar aerosol and water vapor retrievals; using the lidar aerosol profiles to evaluate the accuracy of the vertical distribution of aerosols in global aerosol model simulations; examining the correlation between relative humidity and aerosol extinction, and how these change, due to horizontal distance away from cumulus clouds; inferring boundary layer turbulence structure in convective boundary layers from the high-time-resolution lidar water vapor measurements; retrieving cumulus entrainment rates in boundary layer cumulus clouds; and participating in a field experiment that provided data to help validate both the entrainment rate retrievals and the turbulent profiles derived from lidar observations.

Turner, David, D.; Ferrare, Richard, A.

2011-07-06

293

Comments on ''Accuracy of Raman lidar water vapor calibration and its applicability to long-term measurements''  

SciTech Connect

In a recent publication, Leblanc and McDermid [Appl. Opt., 47, 5592 (2008)]APOPAI0003-693510.1364/AO.47.005592 proposed a hybrid calibration technique for Raman water vapor lidar involving a tungsten lamp and radiosondes. Measurements made with the lidar telescope viewing the calibration lamp were used to stabilize the lidar calibration determined by comparison with radiosonde. The technique provided a significantly more stable calibration constant than radiosondes used alone. The technique involves the use of a calibration lamp in a fixed position in front of the lidar receiver aperture. We examine this configuration and find that such a configuration likely does not properly sample the full lidar system optical efficiency. While the technique is a useful addition to the use of radiosondes alone for lidar calibration, it is important to understand the scenarios under which it will not provide an accurate quantification of system optical efficiency changes. We offer examples of these scenarios. Scanning of the full telescope aperture with the calibration lamp can circumvent most of these limitations. Based on the work done to date, it seems likely that the use of multiple calibration lamps in different fixed positions in front of the telescope may provide sufficient redundancy for long-term calibration needs. Further full-aperture scanning experiments, performed over an extended period of time, are needed to determine a ''best practice'' for the use of multiple calibration lamps in the hybrid technique.

Whiteman, David N.; Venable, Demetrius; Landulfo, Eduardo

2011-05-20

294

Offshore Wind Measurements Using Doppler Aerosol Wind Lidar (DAWN) at NASA Langley Research Center  

NASA Technical Reports Server (NTRS)

The latest flight demonstration of Doppler Aerosol Wind Lidar (DAWN) at NASA Langley Research Center (LaRC) is presented. The goal of the campaign was to demonstrate the improvement of DAWN system since the previous flight campaign in 2012 and the capabilities of DAWN and the latest airborne wind profiling algorithm APOLO (Airborne Wind Profiling Algorithm for Doppler Wind Lidar) developed at LaRC. The comparisons of APOLO and another algorithm are discussed utilizing two and five line-of-sights (LOSs), respectively. Wind parameters from DAWN were compared with ground-based radar measurements for validation purposes. The campaign period was June - July in 2013 and the flight altitude was 8 km in inland toward Charlotte, NC, and offshores in Virginia Beach, VA and Ocean City, MD. The DAWN system was integrated into a UC12B with two operators onboard during the campaign.

Beyon, Jeffrey Y.; Koch, Grady J.; Kavaya, Michael J.

2014-01-01

295

Lidar Investigation of Tropical Nocturnal Boundary Layer Aerosols and Cloud Macrophysics  

SciTech Connect

Observational evidence of two-way association between nocturnal boundary layer aerosols and cloud macrophysical properties under different meteorological conditions is reported in this paper. The study has been conducted during 2008-09 employing a high space-time resolution polarimetric micro-pulse lidar over a tropical urban station in India. Firstly, the study highlights the crucial role of boundary layer aerosols and background meteorology on the formation and structure of low-level stratiform clouds in the backdrop of different atmospheric stability conditions. Turbulent mixing induced by the wind shear at the station, which is associated with a complex terrain, is found to play a pivotal role in the formation and structural evolution of nocturnal boundary layer clouds. Secondly, it is shown that the trapping of energy in the form of outgoing terrestrial radiation by the overlying low-level clouds can enhance the aerosol mixing height associated with the nocturnal boundary layer. To substantiate this, the long-wave heating associated with cloud capping has been quantitatively estimated in an indirect way by employing an Advanced Research Weather Research and Forecasting (WRF-ARW) model version 2.2 developed by National Center for Atmospheric Research (NCAR), Colorado, USA, and supplementary data sets; and differentiated against other heating mechanisms. The present investigation as well establishes the potential of lidar remote-sensing technique in exploring some of the intriguing aspects of the cloud-environment relationship.

Manoj, M. G.; Devara, PC S.; Taraphdar, Sourav

2013-10-01

296

Combining Passive Polarimetric and Lidar Observations from TCAP to Vertically Partition a Multi-Modal Aerosol Model  

NASA Astrophysics Data System (ADS)

The first airborne deployment associated with the Two-Column Aerosol Project (TCAP) field campaign was carried out on Cape Cod, Massachusetts during July 2012 using the DOE Gulfstream 1 (G-1) and the NASA Langley B200. The first column located on Cape Cod has the surface based ARM Mobile Facility, which measures aerosol properties, radiation, and cloud characteristics, as its anchor point. The second column, 200 km to the East, was chosen to facilitate characterization of the large gradient of AOD near the coast of New England. The G-1 was equipped with a suite of in situ instrumentation to measure the size, composition and optics of aerosols, together with spectral Aerosol Optical Depth (AOD) above the aircraft using the Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research. The G1 generally flew at low altitude except when profiling the two columns. The B200, flew at ~ 9 km, above the G1, and operated the world's first airborne three backscatter (355, 532 and 1064 nm) and two extinction (355 and 532 nm) channel high-spectral-resolution lidar, HSRL-2 and the Research Scanning Polarimeter (RSP), which provides multi-angle multi-spectral observations of the intensity and polarization over a spectral range from 410 to 2260 nm. The TCAP measurements are ideal for remote sensing of aerosols since a dark ocean allows the full power of the passive intensity and polarization observations to be explored. RSP observations over the ocean have previously been used to retrieve the AOD, particle size and complex refractive index of aerosols, but it was noted that the vertical distribution of the aerosols could affect the accuracy of the retrieval. In this paper we combine HSRL-2 and RSP data to retrieve and partition a multi-modal aerosol model through the column. The lidar intensive variables (ratios of the lidar observations) that do not depend on aerosol load are used to constrain the microphysics of the aerosol modes. Where the classification technique presented in Burton et al. (2012) identifies layers of distinct aerosol types that information is used in defining the layering of the forward model that is used in the iterative inversion. The HSRL-2 extinction measurements are then used to define the opacity of the vertical layers and an iterative search is executed to find the aerosol types that best match all the RSP observations, while still being compatible with the lidar observations within their associated uncertainties. Other approaches to using such sophisticated lidar measurements are clearly possible and we expect to compare our method with both other analyses of the lidar data and also the in situ and spectral AODs obtained by the G1.

Cairns, B.; Ottaviani, M.; Knobelspiesse, K. D.; Chowdhary, J.; Hostetler, C. A.; Ferrare, R. A.; Hair, J. W.; Cook, A. L.; Harper, D. B.; Mack, T. L.; Hare, R. J.; Cleckner, C. S.; Rogers, R.; Mueller, D.; Burton, S. P.; Obland, M. D.; Scarino, A. J.; Redemann, J.; Schmid, B.; Fast, J. D.; Berg, L. K.

2012-12-01

297

Airborne High Spectral Resolution Lidar Aerosol Measurements During the First DISCOVER-AQ Field Mission  

NASA Astrophysics Data System (ADS)

The NASA Langley Research Center (LaRC) airborne High Spectral Resolution Lidar (HSRL) measured profiles of aerosol extinction (532 nm), aerosol optical depth (AOD) (532 nm), backscatter (532 and 1064 nm), and depolarization (532 and 1064 nm) while deployed on the NASA Langley Research Center UC12 aircraft during the first field experiment conducted as part of the NASA Deriving Information on Surface Conditions from COlumn and VERtically Resolved Observations Relevant to Air Quality (DISCOVER-AQ) Mission. The main objective of DISCOVER AQ is to improve the interpretation of satellite observations of key trace gases and aerosols that are used to diagnose near surface conditions relating to air quality. During the first DISCOVER-AQ field mission the HSRL acquired more than 100 hours of data over the Baltimore-Washington D.C. area during 27 flights conducted on 13 days in July 2011. In situ instruments on the NASA P-3 aircraft measured aerosol optical and microphysical parameters within the HSRL "curtains" thereby facilitating extensive intercomparisons and combined analyses. Initial comparisons show good agreement between aerosol extinction profiles measured by HSRL and those derived from the in situ P-3 measurements. Measurements from the HSRL, MODIS and MISR spaceborne sensors, and a network of over 40 ground based Sun photometers are used to examine the spatial variability of AOD over this region. HSRL measurements show significant variability of Planetary Boundary Layer (PBL) heights and AOD over this region, particularly when comparing the measurements acquired over land with those measured over the nearby Chesapeake Bay. Aerosol extinction profiles showed considerable spatial and temporal variability; highest values often occurred well away from the surface in layers with high relative humidity. Aerosol intensive parameters measured by HSRL (e.g. backscatter Angström exponent, depolarization, and extinction/backscatter "lidar" ratio) are also shown to vary with relative humidity. HSRL measurements are also used to help assess AOD, PBL heights, and PM2.5 concentrations simulated by the NOAA experimental version of the Community Multiscale Air Quality (CMAQ) Model and aerosol profiles produced by the Goddard Earth Observing System-5 (GEOS-5) model.

Ferrare, R. A.; Hostetler, C. A.; Hair, J. W.; Obland, M. D.; Rogers, R.; Cook, A.; Harper, D.; Hare, R.; Burton, S. P.; Anderson, B. E.; Crawford, J. H.; Swanson, A. J.; Clayton, M.; Thornhill, K. L.; Holben, B.; Pickering, K. E.; Kahn, R. A.; DaSilva, A.; Chu, D.; Hoff, R. M.; Delgado, R.; Compton, J. S.; Berkoff, T.; Lee, P.

2011-12-01

298

Design, Qualification, and On Orbit Performance of the CALIPSO Aerosol Lidar Transmitter  

NASA Technical Reports Server (NTRS)

The laser transmitter for the CALIPSO aerosol lidar mission has been operating on orbit as planned since June 2006. This document discusses the optical and laser system design and qualification process that led to this success. Space-qualifiable laser design guidelines included the use of mature laser technologies, the use of alignment sensitive resonator designs, the development and practice of stringent contamination control procedures, the operation of all optical components at appropriately derated levels, and the proper budgeting for the space-qualification of the electronics and software.

Hovis, Floyd E.; Witt, Greg; Sullivan, Edward T.; Le, Khoa; Weimer, Carl; Applegate, Jeff; Luck, William S., Jr.; Verhapen, Ron; Cisewski, Michael S.

2007-01-01

299

Cloud-Aerosol LIDAR and Infrared Pathfinder Satellite Observation (CALIPSO) Spacecraft: Independent Technical Assessment  

NASA Technical Reports Server (NTRS)

CALIPSO is a joint science mission between the CNES, LaRC and GSFC. It was selected as an Earth System Science Pathfinder satellite mission in December 1998 to address the role of clouds and aerosols in the Earth's radiation budget. The spacecraft includes a NASA light detecting and ranging (LIDAR) instrument, a NASA wide-field camera and a CNES imaging infrared radiometer. The scope of this effort was a review of the Proteus propulsion bus design and an assessment of the potential for personnel exposure to hydrazine propellant.

Gilbrech, Richard J.; McManamen, John P.; Wilson, Timmy R.; Robinson, Frank; Schoren, William R.

2004-01-01

300

Visibility and aerosol measurement by diode-laser random-modulation CW lidar  

NASA Technical Reports Server (NTRS)

Examples of diode laser (DL) random-modulation continuous wave (RM-CW) lidar measurements are reported. The ability of the measurement of the visibility, vertical aerosol profile, and the cloud ceiling height is demonstrated. Although the data shown here were all measured at night time, the daytime measurement is, of course, possible. For that purpose, accurate control of the laser frequency to the center frequency of a narrow band filter is required. Now a new system with a frequency control is under construction.

Takeuchi, N.; Baba, H.; Sakurai, K.; Ueno, T.; Ishikawa, N.

1986-01-01

301

A Comparison of High Spectral Resolution and Raman Lidars O (a work in progress with much left to be done)  

E-print Network

ratio Raman/HSRL 0.600 2.250 300.000 44.444 801.000 100.125 684.000 0.374 1.000 2.000 387.000 0.727 0.540 0.640 31.000 0.008 27.035 We compare the HSRL Rayleigh scattered molecular lidar return sensitivity is at least partly due to optical imperfections in the telescope. Tests on a new HSRL

Eloranta, Edwin W.

302

Micropulse lidar observations of tropospheric aerosols over northeastern South Africa during the ARREX and SAFARI 2000 dry season experiments  

NASA Astrophysics Data System (ADS)

During the Aerosol Recirculation and Rainfall Experiment (ARREX 1999) and Southern African Regional Science Initiative (SAFARI 2000) dry season experiments, a micropulse lidar (523 nm) instrument was operated at the Skukuza Airport in northeastern South Africa. The lidar was colocated with a diverse array of passive radiometric equipment. For SAFARI 2000, a daytime time series of layer mean aerosol optical properties, including layer mean extinction-to-backscatter ratios and vertical extinction cross-section profiles are derived from the synthesis of the lidar data and aerosol optical depths from available AERONET Sun photometer data. Combined with derived spectral Angstrom exponents, normalized broadband flux measurements, and calculated air mass back-trajectories, the temporal evolution of the surface aerosol layer optical properties is analyzed for climatological trends. For dense biomass smoke events the extinction-to-backscatter ratio is between 50 and 90 sr, and corresponding spectral Angstrom exponent values are between 1.50 and 2.00. Observations of an advecting smoke event during SAFARI 2000 are shown. The smoke was embedded within two distinct stratified thermodynamic layers causing the particulate mass to advect over the instrument array in an incoherent manner on the afternoon of 1 September 2000. Significant surface broadband flux forcing of over -50 W/m2 was measured in this event. The evolution of the vertical aerosol extinction profile is profiled using the lidar data. Finally, observations of persistent elevated aerosol layers during ARREX 1999 are presented and discussed. Back-trajectory analyses combined with lidar and Sun photometer measurements indicate the likelihood for these aerosols being the result of long-range particulate transport from the southern and central South America.

Campbell, James R.; Welton, Ellsworth J.; Spinhirne, James D.; Ji, Qiang; Tsay, Si-Chee; Piketh, Stuart J.; Barenbrug, Marguerite; Holben, Brent N.

2003-07-01

303

Monitoring Aerosol Optical Properties in the ABL, Using Lidar System and Sunphotometer in Buenos Aires, Argentina  

NASA Astrophysics Data System (ADS)

At the Lasers and Applications Research Center (CEILAP, CITEFA-CONICET, (34°33' S, 58°30' W), located in an industrial suburb of the metropolitan area (Villa Martelli, Buenos Aires, Argentina), operates a multiwavelength lidar, based on a Nd:Yag laser (Continuum Surelite III P-IV). This system emits in 1064, 532 and 355 nm simultaneously (10 Hz, 600 mJ @ 1064 nm) and allows the monitoring of the optical aerosols properties in the atmospheric boundary layer (ABL). On the same experimental site, an AERONET sunphotometer provides the AOT value. An analysis of boundary layer behaviour in some relevant days of March, from the years 2004 to 2006 is presented. On the days analyzed, no aerosols events and clouds were registered over the ABL. Evolutions of some characteristics of the ABL are presented, such as the height of the boundary layer, height of entrainment zone (EZ) and the entrainment flux ratio.

Pallotta, J.; Pawelko, E.; Otero, L.; Ristori, P.; D'Elia, R.; Gonzalez, F.; Dworniczak, J.; Vilar, O.; Quel, E.

2009-03-01

304

Southern Hemisphere Lidar Measurements of the Aerosol Clouds from Mt. Pinatubo and Mt. Hudson  

NASA Technical Reports Server (NTRS)

On 19 Jul., 1991, during tests to determine the ability of the newly-modified CSIRO Ns:YAG lidar to measure signals from the stratosphere before the arrival of dust from the eruption of Mt. Pinatubo, a strongly scattering layer was detected at an altitude of 2 km. That evening, the spectacular sunset and twilight were typical of volcanically disturbed conditions. Lidar measurements at 532 nm were made between 1400 and 1500 EST (0400-0500 UT) on 19 Jul. through broken cloud. Approximately 3800 laser firings were averaged in 256 shot blocks. These and subsequent data have been analyzed to produce profiles of aerosol volume backscatter function and scattering ratio. Clouds again prevented a clear view of the twilights on the next two nights, although there was some evidence for an enhanced glow. The evidence suggested that the aerosol layer had disappeared. An explanation for this disappearance and the earlier than expected arrival of the layer over Melbourne was required. Nimbus 7 TOMS data for 23 Jun. showed that the SO2 from the eruption had extended at least 11000 km to the west and that the southern boundary of the cloud had reached 15 degrees S just 8 days after the climactic eruption. It can be assumed that this cloud also contained dust and sulphuric acid aerosol. It was proposed that a section had then been broken away from the main cloud and carried south by a large scale eddy between the low latitude easterlies and the strong mid-latitude westerlies which finally carried the aerosol cloud over southern Australia. Accompanying 30 mb wind data showed a counter clockwise circulation, responsible for the transport, located in the South Atlantic Ocean.

Young, Stuart A.; Manson, Peter J.; Patterson, Graeme R.

1992-01-01

305

Validation of the Lidar In-Space Technology Experiment: stratospheric temperature and aerosol measurements.  

PubMed

The Lidar In-Space Technology Experiment (LITE) was flown on STS-64 in September 1994. The LITE employed a Nd:YAG laser operating at 1064, 532, and 355 nm to study the Earth's lower atmosphere. In this paper we investigate the nighttime stratospheric aerosol and temperature measurements derived from the 532- and 355-nm channels. The observations are compared with lidar observations obtained at Arecibo Observatory, Puerto Rico, and Starfire Optical Range, New Mexico, and with balloonsondes launched from the San Juan and Albuquerque airports. The backscatter ratios derived from the LITE and Arecibo data between 15 and 30 km differ by less than 5%. The Angstrom coefficients of the stratospheric aerosols derived from the 532- and 355-nm LITE channels exhibited only slight variation in altitude. The mean value between 15 and 30 km derived from three different orbital segments at approximately 20 degrees N and 35 degrees N was 1.7. The mean standard deviation was approximately 0.3. Temperature profiles were derived from the LITE data by correcting the 355-nm channel for aerosol scattering with the 532-nm signal and an assumed Angstrom coefficient. The rms differences between the corrected profiles and the balloonsonde data were as low as 2 K in the 15-30-km height range. The results were not particularly sensitive to the choice of the Angstrom coefficient and suggest that accurate temperature profiles can be derived from the LITE data in the upper troposphere and lower stratosphere provided that the aerosol loading is light. PMID:18259328

Gu, Y Y; Gardner, C S; Castleberg, P A; Papen, G C; Kelley, M C

1997-07-20

306

Lidar Measurements of Stratospheric Ozone, Aerosols and Temperature during the SAUNA Campaign at Sodankyla, Finland  

NASA Technical Reports Server (NTRS)

The Sodankyla Total Column Ozone Intercomparison (SAUNA) campaign took place at the Finnish Meteorological Institute Arctic Research Center (FMI-ARC) at Sodankyla, Finland (67.37 N) in two separate phases during early spring 2006, and winter 2007. These campaigns has several goals: to determine and improve the accuracy of total column ozone measurements during periods of low solar zenith angle and high total column ozone; to determine the effect of ozone profile shape on the total column retrieval; and to make validate satellite ozone measurements under these same conditions. The GSFC Stratospheric Ozone Lidar (STROZ), which makes profile measurements of ozone temperature, aerosols and water vapor participated in both phases of the campaign. During the deployments, more than 30 profile measurements were made by the lidar instrument, along with Dobson, Brewer, DOAS, ozonesonde, and satellite measurements. The presentation will concentrate on STROZ lidar results from the second phase of the campaign and comparisons with other instruments will be discussed. This will include both ground-based and satellite comparisons.

McGee, T.; Twigg, L.; Sumnicht, G.; McPeters, R.; Bojkov, B.; Kivi, R.

2008-01-01

307

Infrared lidar overlap function: an experimental determination.  

PubMed

The most recent works demonstrate that the lidar overlap function, which describes the overlap between the laser beam and the receiver field of view, can be determined experimentally for the 355 and 532 nm channels using Raman signals. Nevertheless, the Raman channels cannot be used to determine the lidar overlap for the infrared channel (1064 nm) because of their low intensity. In addition, many Raman lidar systems only provide inelastic signals with reasonable signal-to-noise ratio at nighttime. In view of this fact, this work presents a modification of that method, based on the comparison of attenuated backscatter profiles derived from lidar and ceilometer, to retrieve the overlap function for the lidar infrared channel. Similarly to the Raman overlap method, the approach presented here allows to derive the overlap correction without an explicit knowledge of all system parameters. The application of the proposed methodology will improve the potential of Raman lidars to investigate the aerosol microphysical properties in the planetary boundary layer, extending the information of 1064 nm backscatter profiles to the ground and allowing the retrieval of microphysical properties practically close to the surface. PMID:20940927

Guerrero-Rascado, Juan Luis; Costa, Maria João; Bortoli, Daniele; Silva, Ana Maria; Lyamani, Hassan; Alados-Arboledas, Lucas

2010-09-13

308

Investigation of wintertime cold-air pools and aerosol layers in the Salt Lake Valley using a lidar ceilometer  

NASA Astrophysics Data System (ADS)

This thesis investigates the utility of lidar ceilometers, a type of aerosol lidar, in improving the understanding of meteorology and air quality in persistent wintertime stable boundary layers, or cold-air pools, that form in urbanized valley and basin topography. This thesis reviews the scientific literature to survey the present knowledge of persistent cold-air pools, the operating principles of lidar ceilometers, and their demonstrated utility in meteorological investigations. Lidar ceilometer data from the Persistent Cold-Air Pool Study (PCAPS) are then used with meteorological and air quality data from other in situ and remote sensing equipment to investigate cold-air pools that formed in Utah's Salt Lake Valley during the winter of 2010-2011. The lidar ceilometer is shown to accurately measure aerosol layer depth and aerosol loading, when compared to visual observations. A linear relationship is found between low-level lidar backscatter and surface particulate measurements. Convective boundary layer lidar analysis techniques applied to cold-air pool ceilometer profiles can detect useful layer characteristics. Fine-scale waves are observed and analyzed within the aerosol layer, with emphasis on Kelvin-Helmholz waves. Ceilometer aerosol backscatter profiles are analyzed to quantify and describe mixing processes in persistent cold-air pools. Overlays of other remote and in-situ observations are combined with ceilometer particle backscatter to describe specific events during PCAPS. This analysis describes the relationship between the aerosol layer and the valley inversion as well as interactions with large-scale meteorology. The ceilometer observations of hydrometers are used to quantify cloudiness and precipitation during the project, observing that 50% of hours when a PCAP was present had clouds or precipitation below 5 km above ground level (AGL). Then, combining an objective technique for determining hourly aerosol layer depths and correcting this subjectively during periods with low clouds or precipitation, a time series of aerosol depths was obtained. The mean depth of the surface-based aerosol layer during PCAP events was 1861 m MSL with a standard deviation of 135 m. The aerosol layer depth, given the approximate 1300 m altitude of the valley floor, is thus about 550 m, about 46% of the basin depth. The aerosol layer is present during much of the winter and is removed only during strong or prolonged precipitation periods or when surface winds are strong. Nocturnal fogs that formed near the end of high-stability PCAP episodes had a limited effect on aerosol layer depth. Aerosol layer depth was relatively invariant during the winter and during the persistent cold-air pools, while PM10 concentrations at the valley floor varied with bulk atmospheric stability associated primarily with passage of large-scale high- and low-pressure weather systems. PM10 concentrations also increased with cold-air pool duration. Mean aerosol loading in the surface-based aerosol layer, as determined from ceilometer backscatter coefficients, showed weaker variations than those of surface PM10 concentrations, suggesting that ineffective vertical mixing and aerosol layering are present in the cold-air pools. This is supported by higher time-resolution backscatter data, and it distinguishes the persistent cold-air pools from well-mixed convective boundary layers where ground-based air pollution concentrations are closely related to time-dependent convective boundary layer/aerosol depths. These results are discussed along with recommendations for future explorations of the ceilometer and cold-air pool topics.

Young, Joseph Swyler

309

Global Lidar Measurements of Clouds and Aerosols from Space Using the Geoscience Laser Altimeter System (GLAS)  

NASA Technical Reports Server (NTRS)

The Geoscience Laser Altimeter System (GLAS) is scheduled for launch on the ICESat satellite as part of the NASA EOS mission in 2002. GLAS will be used to perform high resolution surface altimetry and will also provide a continuously operating atmospheric lidar to profile clouds, aerosols, and the planetary boundary layer with horizontal and vertical resolution of 175 and 76.8 m, respectively. GLAS is the first active satellite atmospheric profiler to provide global coverage. Data products include direct measurements of the heights of aerosol and cloud layers, and the optical depth of transmissive layers. In this poster we provide an overview of the GLAS atmospheric data products, present a simulated GLAS data set, and show results from the simulated data set using the GLAS data processing algorithm. Optical results from the ER-2 Cloud Physics Lidar (CPL), which uses many of the same processing algorithms as GLAS, show algorithm performance with real atmospheric conditions during the Southern African Regional Science Initiative (SAFARI 2000).

Hlavka, Dennis L.; Palm, S. P.; Welton, E. J.; Hart, W. D.; Spinhirne, J. D.; McGill, M.; Mahesh, A.; Starr, David OC. (Technical Monitor)

2001-01-01

310

Airborne lidar measurements of El Chichon stratospheric aerosols, October 1982 to November 1982  

NASA Technical Reports Server (NTRS)

A coordinated flight mission to determine the spatial distribution and aerosol characteristics of the El Chichon produced stratospheric aerosol was flown in October to November 1982. The mission covered 46 deg N to 46 deg S and included rendezvous between balloon-, airplane-, and satellite-borne sensors. The lidar data from the flight mission are presented. Representative profiles of lidar backscatter ratio, plots of the integrated backscattering function versus latitude, and contours of backscatter mixing ratio versus altitude and latitude are given. In addition, tables containing numerical values of the backscatter ratio and backscattering functions versus altitude are supplied for each profile. The bulk of the material produced by the El Chichon eruptions of late March 10 to early April 1982 resided between latitudes from 5 to 7 deg S to 35 to 37 deg N and was concentrated above 21 km in a layer that peaked at 23 to 25 km. In this latitude region, peak scattering ratios at a wavelength of 0.6943 micron were approximately 24. The results of this mission are presented in a ready-to-use format for atmospheric and climatic studies.

Mccormick, M. P.; Osborn, M. T.

1985-01-01

311

Combining passive polarimetric remote sensing and advanced measurements of lidar intensive variables in vertically resolved aerosol retrievals  

NASA Astrophysics Data System (ADS)

Passive polarimetric measurements can be used to retrieve aerosol size distribution, composition and loading over ocean, land and clouds. The primary limitation is the need for prior assumptions about the aerosol vertical distribution. For example a number concentration that is exponentially decaying from the surface up, or a detached layer are reasonable a priori guesses. However, errors in the assumed vertical distribution can adversely affect the aerosol retrievals. Lidar measurements are therefore highly complementary to passive polarimetry since they can be used to prescribe the vertical distribution of aerosols. Merging elastic backscatter lidar measurements with passive aerosol retrievals is at least conceptually straightforward and has been demonstrated for a number of cases. Of particular interest for future missions examining the roles of aerosols and clouds in climate are advanced high spectral resolution lidar (HSRL) systems that provide direct measure(s) of extinction in addition to measurements of backscatter and depolarization. The focus for combining measurements of this kind with passive polarimetric measurements is to generate vertical profiles of extinction, scattering and particle type that can be used to determine the heating rate. In this paper we will assess how well a multi-modal model in which only the number concentration of each mode varies in the vertical can match HSRL and passive polarimetric measurements. The modal properties are adjusted to match the observations at each step in an iterative retrieval. As part of our evaluation we identify the modal properties that are weakly constrained and the consequent uncertainties in predicted heating rates.

Frost, J.; Rodriguez, L.; Burton, S. P.; Ferrare, R. A.; Hostetler, C. A.; Cairns, B.

2012-12-01

312

Aerosol Transport Questions Arising From Micro Pulse Lidar Measurements During MILAGRO  

NASA Astrophysics Data System (ADS)

A Micro Pulse Lidar (MPL) was operated by Argonne National Laboratory at the Universidad de Tecámac site (T1) during the MILAGRO field campaign in March 2006 in the environs of Mexico City. Located approximately 40 km north of the urban center of Mexico City, the T1 site was expected to observe the transport and evolution of aerosols as they moved out of the urban area on predominantly south winds. Because of the collocation of numerous other remote and in-situ sensors of aerosols, winds, temperatures and moisture. The MPL, operating at 0.527 microns, provides estimates of scattering in 15 m range (height) intervals, averaged over 10 sec between 200 m and (characteristically) 15 km, from which extinction profiles through and above the mixed layer can be calculated, mixed layer heights and evolution obtained and stratification and modification of aerosols observed. During the MILAGRO field campaign the growth of the mixed layer during daytime and the stratification of the atmosphere and subsequent aerosol layering were typical of previous campaigns and agreed well with structure observed by radar wind profiler, sodar, and radiosonde profiles. However, on many evenings very near sunset (1800 LT), a marked decrease in apparent aerosol concentration was observed through much of the depth of the mixed layer that persisted for 1-2 hours. Aerosol concentrations calculated with the CMAQ model coupled with MM5 wind fields will be evaluated with measured vertical profiles. Estimates of local radiative forcing for this site will be generated using MPL data set and model results.

Kotamarthi, R.; Coulter, R.; Pekour, M.

2007-12-01

313

Oceanic Lidar  

NASA Technical Reports Server (NTRS)

Instrument concepts which measure ocean temperature, chlorophyll, sediment and Gelbstoffe concentrations in three dimensions on a quantitative, quasi-synoptic basis were considered. Coastal zone color scanner chlorophyll imagery, laser stimulated Raman temperaure and fluorescence spectroscopy, existing airborne Lidar and laser fluorosensing instruments, and their accuracies in quantifying concentrations of chlorophyll, suspended sediments and Gelbstoffe are presented. Lidar applications to phytoplankton dynamics and photochemistry, Lidar radiative transfer and signal interpretation, and Lidar technology are discussed.

Carder, K. L. (editor)

1981-01-01

314

BACKSCAT lidar simulation version 3.0: Technical documentation and users guide  

NASA Astrophysics Data System (ADS)

The Geophysics Directorate of Phillips Laboratory is developing a number of lidar systems for use in probing the atmosphere. These systems include backscatter lidars to study atmospheric aerosols, Doppler lidar systems to measure wind fields, and Raman lidars to study the distributions of different molecular species. To aid in the design and use of such lidar systems, SPARTA has developed a lidar simulation program, BACKSCAT. Originally developed to include only the backscattered return from aerosols, the simulation package has evolved to include Raman scattering processes. BACKSCAT Version 3.0 includes two significant improvements. The first is the inclusion of user-defined aerosol layers and the second is the consideration of Raman scattering processes. In BACKSCAT Version 3.0, a user-defined aerosol layer is defined by a number density profile, a size distribution shape, and an index of refraction. Aerosol attenuation properties are computed using an efficient Mie scattering program that is coupled to the BACKSCAT simulation system. Users can select from a library of aerosol indices of refraction for common aerosols or they can input specific values.

Hummel, John R.; Longtin, David R.; Depiero, Nanette L.; Grasso, Robert J.

1992-12-01

315

Global Observations of Aerosols and Clouds from Combined Lidar and Passive Instruments to Improve Radiation Budget and Climate Studies  

NASA Technical Reports Server (NTRS)

Current uncertainties in the effects of clouds and aerosols on the Earth radiation budget limit our understanding of the climate system and the potential for global climate change. Pathfinder Instruments for Cloud and Aerosol Spaceborne Observations - Climatologie Etendue des Nuages et des Aerosols (PICASSO-CENA) is a recently approved satellite mission within NASA's Earth System Science Pathfinder (ESSP) program which will address these uncertainties with a unique suite of active and passive instruments. The Lidar In-space Technology Experiment (LITE) demonstrated the potential benefits of space lidar for studies of clouds and aerosols. PICASSO-CENA builds on this experience with a payload consisting of a two-wavelength polarization-sensitive lidar, an oxygen A-band spectrometer (ABS), an imaging infrared radiometer (IIR), and a wide field camera (WFC). Data from these instruments will be used to measure the vertical distributions of aerosols and clouds in the atmosphere, as well as optical and physical properties of aerosols and clouds which influence the Earth radiation budget. PICASSO-CENA will be flown in formation with the PM satellite of the NASA Earth Observing System (EOS) to provide a comprehensive suite of coincident measurements of atmospheric state, aerosol and cloud optical properties, and radiative fluxes. The mission will address critical uncertainties iin the direct radiative forcing of aerosols and clouds as well as aerosol influences on cloud radiative properties and cloud-climate radiation feedbacks. PICASSO-CENA is planned for a three year mission, with a launch in early 2003. PICASSO-CENA is being developed within the framework of a collaboration between NASA and CNES.

Winker, David M.

1999-01-01

316

Characterizing the Vertical Distribution of Aerosols Over the ARM SGP Site  

SciTech Connect

This project focused on: 1) evaluating the performance of the DOE ARM SGP Raman lidar system in measuring profiles of water vapor and aerosols, and 2) the use of the Raman lidar measurements of aerosol and water vapor profiles for assessing the vertical distribution of aerosols and water vapor simulated by global transport models and examining diurnal variability of aerosols and water vapor. The highest aerosol extinction was generally observed close to the surface during the nighttime just prior to sunrise. The high values of aerosol extinction are most likely associated with increased scattering by hygroscopic aerosols, since the corresponding average relative humidity values were above 70%. After sunrise, relative humidity and aerosol extinction below 500 m decreased with the growth in the daytime convective boundary layer. The largest aerosol extinction for altitudes above 1 km occurred during the early afternoon most likely as a result of the increase in relative humidity. The water vapor mixing ratio profiles generally showed smaller variations with altitude between day and night. We also compared simultaneous measurements of relative humidity, aerosol extinction, and aerosol optical thickness derived from the ARM SGP Raman lidar and in situ instruments on board a small aircraft flown routinely over the ARM SGP site. In contrast, the differences between the CARL and IAP aerosol extinction measurements are considerably larger. Aerosol extinction derived from the IAP measurements is, on average, about 30-40% less than values derived from the Raman lidar. The reasons for this difference are not clear, but may be related to the corrections for supermicron scattering and relative humidity that were applied to the IAP data. The investigators on this project helped to set up a major field mission (2003 Aerosol IOP) over the DOE ARM SGP site. One of the goals of the mission was to further evaluate the aerosol and water vapor retrievals from this lidar system. Analysis of the aerosol and water vapor data collected by the Raman lidar during the 2003 Aerosol IOP indicated that the sensitivity of the lidar was significantly lower than when the lidar was initially deployed. A detailed analysis after the IOP of the long-term dataset demonstrated that the lidar began degrading in early 2002, and that it lost approximately a factor of 4 in sensitivity between 2002 and 2004. We participated in the development of the remediation plan for the system to restore its initial performance. We conducted this refurbishment and upgrade from May- September 2004. This remediation lead to an increase in the signal-to-noise ratio of 10 and 30 for the Raman lidar's water vapor mixing ratio and aerosol backscatter coefficient data, respectively as compared to the signal strengths when the system was first deployed. The DOE ARM Aerosol Lidar Validation Experiment (ALIVE), which was conducted during September 2005, evaluated the impact of these modifications and upgrades on the SGP Raman lidar measurements of aerosol extinction and optical thickness. The CARL modifications significantly improved the accuracy and temporal resolution of the aerosol measurements. Aerosol extinction profiles measured by the Raman lidar were also used to evaluate aerosol extinction profiles and aerosol optical thickness (AOT) simulated by aerosol models as part of the Aerosol module inter-Comparison in global models (AEROCOM) (http://nansen.ipsl.jussieu.fr/AEROCOM/aerocomhome.html) project. There was a wide range in how the models represent the aerosol extinction profiles over the ARM SGP site, even though the average annual AOT represented by the various models and measured by CARL and the Sun photometer were in general agreement, at least within the standard deviations of the averages. There were considerable differences in the average vertical distributions among the models, even among models that had similar average aerosol optical thickness. Deviations between mean aerosol extinction profiles were generally small (~20-30%) for altitudes above 2 km, and grew consider

Richard Ferrare, Connor Flynn, David Turner

2009-05-05

317

Measurements of the Vertical Structure of Aerosols and Clouds Over the Ocean Using Micro-Pulse LIDAR Systems  

NASA Technical Reports Server (NTRS)

The determination of the vertical distribution of aerosols and clouds over the ocean is needed for accurate retrievals of ocean color from satellites observations. The presence of absorbing aerosol layers, especially at altitudes above the boundary layer, has been shown to influence the calculation of ocean color. Also, satellite data must be correctly screened for the presence of clouds, particularly cirrus, in order to measure ocean color. One instrument capable of providing this information is a lidar, which uses pulses of laser light to profile the vertical distribution of aerosol and cloud layers in the atmosphere. However, lidar systems prior to the 1990s were large, expensive, and not eye-safe which made them unsuitable for cruise deployments. During the 1990s the first small, autonomous, and eye-safe lidar system became available: the micro-pulse lidar, or MPL. The MPL is a compact and eye-safe lidar system capable of determining the range of aerosols and clouds by firing a short pulse of laser light (523 nm) and measuring the time-of-flight from pulse transmission to reception of a returned signal. The returned signal is a function of time, converted into range using the speed of light, and is proportional to the amount of light backscattered by atmospheric molecules (Rayleigh scattering), aerosols, and clouds. The MPL achieves ANSI eye-safe standards by sending laser pulses at low energy (micro-J) and expanding the beam to 20.32 cm in diameter. A fast pulse-repetition-frequency (2500 Hz) is used to achieve a good signal-to-noise, despite the low output energy. The MPL has a small field-of-view (< 100 micro-rad) and signals received with the instrument do not contain multiple scattering effects. The MPL has been used successfully at a number of long-term sites and also in several field experiments around the world.

Welton, Ellsworth J.; Spinhirne, James D.; Campbell, James R.; Berkoff, Timothy A.; Bates, David; Starr, David OC. (Technical Monitor)

2001-01-01

318

Analysis of Raman Lidar and Radiosonde Measurements from the AWEX-G Field Campaign and Its Relation to Aqua Validation  

NASA Technical Reports Server (NTRS)

Early work within the Aqua validation activity revealed there to be large differences in water vapor measurement accuracy among the various technologies in use for providing validation data. The validation measurements were made at globally distributed sites making it difficult to isolate the sources of the apparent measurement differences among the various sensors, which included both Raman lidar and radiosonde. Because of this, the AIRS Water Vapor Experiment-Ground (AWEX-G) was held in October-November 2003 with the goal of bringing validation technologies to a common site for intercomparison and resolving the measurement discrepancies. Using the University of Colorado Cryogenic Frostpoint Hygrometer (CFH) as the water vapor reference, the AWEX-G field campaign permitted correction techniques to be validated for Raman lidar, Vaisala RS80-H and RS90/92 that significantly improve the absolute accuracy of water vapor measurements from these systems particularly in the upper troposphere. Mean comparisons of radiosondes and lidar are performed demonstrating agreement between corrected sensors and the CFH to generally within 5% thereby providing data of sufficient accuracy for Aqua validation purposes. Examples of the use of the correction techniques in radiance and retrieval comparisons are provided and discussed.

Whiteman, D. N.; Russo, F.; Demoz, B.; Miloshevich, L. M.; Veselovskii, I.; Hannon, S.; Wang, Z.; Vomel, H.; Schmidlin, F.; Lesht, B.; Moore, P. J.; Beebe, A. S.; Gambacorta, A.; Barnet, C.

2006-01-01

319

Analysis of Raman Lidar and radiosonde measurements from the AWEX-G field campaign and its relation to Aqua validation  

NASA Technical Reports Server (NTRS)

Early work within the Aqua validation activity revealed there to be large differences in water vapor measurement accuracy among the various technologies in use for providing validation data. The validation measurements were made at globally distributed sites making it difficult to isolate the sources of the apparent measurement differences among the various sensors, which included both Raman lidar and radiosonde. Because of this, the AIRS Water Vapor Experiment-Ground (AWEX-G) was held in October - November, 2003 with the goal of bringing validation technologies to a common site for intercomparison and resolution of the measurement discrepancies. Using the University of Colorado Cryogenic Frostpoint Hygrometer (CFH) as the water vapor reference, the AWEX-G field campaign resulted in new correction techniques for both Raman lidar, Vaisala RS80-H and RS90/92 measurements that significantly improve the absolute accuracy of those measurement systems particularly in the upper troposphere. Mean comparisons of radiosondes and lidar are performed demonstrating agreement between corrected sensors and the CFH to generally within 5% thereby providing data of sufficient accuracy for Aqua validation purposes. Examples of the use of the correction techniques in radiance and retrieval comparisons are provided and discussed.

Whiteman, D. N.; Russo, F.; Demoz, B.; Miloshevich, L. M.; Veselovskii, I.; Hannon, S.; Wang, Z.; Vomel, H.; Schmidlin, F.; Lesht, B.

2005-01-01

320

Self-Raman Nd:YVO4 laser and electro-optic technology for space-based sodium lidar instrument  

NASA Astrophysics Data System (ADS)

We are developing a laser and electro-optic technology to remotely measure Sodium (Na) by adapting existing lidar technology with space flight heritage. The developed instrumentation will serve as the core for the planning of an Heliophysics mission targeted to study the composition and dynamics of Earth's mesosphere based on a spaceborne lidar that will measure the mesospheric Na layer. We present performance results from our diode-pumped tunable Q-switched self-Raman c-cut Nd:YVO4 laser with intra-cavity frequency doubling that produces multi-watt 589 nm wavelength output. The c-cut Nd:YVO4 laser has a fundamental wavelength that is tunable from 1063-1067 nm. A CW External Cavity diode laser is used as a injection seeder to provide single-frequency grating tunable output around 1066 nm. The injection-seeded self-Raman shifted Nd:VO4 laser is tuned across the sodium vapor D2 line at 589 nm. We will review technologies that provide strong leverage for the sodium lidar laser system with strong heritage from the Ice Cloud and Land Elevation Satellite-2 (ICESat-2) Advanced Topographic Laser Altimeter System (ATLAS). These include a space-qualified frequency-doubled 9W @ 532 nm wavelength Nd:YVO4 laser, a tandem interference filter temperature-stabilized fused-silica-etalon receiver and high-bandwidth photon-counting detectors.

Krainak, Michael A.; Yu, Anthony W.; Janches, Diego; Jones, Sarah L.; Blagojevic, Branimir; Chen, Jeffrey

2014-02-01

321

Atmospheric temperature measurements at altitudes of 5-30??km with a double-grating-based pure rotational Raman lidar.  

PubMed

A pure rotational Raman (PRR) lidar based on a second-harmonic generation Nd:YAG laser is built for measuring the atmospheric temperature at altitudes of 5-30 km. A double-grating polychromator is designed to extract the wanted PRR signals and suppress the elastically backscattered light. Measured examples present the overall lidar performance. For the 1-h integrated lidar temperature profiles, the 1? statistical uncertainty is less than 0.5 K up to ?17??km, while it does not exceed 2 K at altitudes of 17-26.3 km. Based on 38 nights of high-quality lidar temperature data, the temperature variability is studied. It is found that the variability differs between the nights with inversion layer and those without it. On the nights without inversion layer, the local hour-to-hour temperature variability was mostly less than 1 K at altitudes of 5-17 km. At altitudes of 17-23 km, it grew to 1.2-2.4 K. On the nights with inversion layer, in the middle and upper troposphere, the significant variability was found to occur only at the inversion-layer altitudes. At other tropospheric altitudes off the inversion layer, the variability was generally less than 1 K. The statistical results indicate that the temperature variability mostly was stronger in the presence of inversion layer than in its absence. PMID:25321103

Jia, Jingyu; Yi, Fan

2014-08-20

322

Water vapor observations up to the lower stratosphere through the Raman lidar during the MAïdo LIdar Calibration Campaign  

NASA Astrophysics Data System (ADS)

A new lidar system devoted to tropospheric and lower stratospheric water vapor measurements has been installed at the Maïdo altitude station facility of La Reunion Island, in the southern subtropics. The main objectives of the MAïdo LIdar Calibration Campaign (MALICCA), performed in April 2013, were to validate the system, to set up a calibration methodology, to compare the acquired water profiles with radiosonde measurements and to evaluate its performances and capabilities with a particular focus on the UTLS measurements. Varying the characteristics of the transmitter and the receiver components, different system configuration scenarios were tested and possible parasite signals (fluorescent contamination, rejection) were investigated. A hybrid calibration methodology has been set up and validated to insure optimal lidar calibration stability with time. In particular, the receiver transmittance is monitored through the calibration lamp method that, at the moment, can detect transmittance variations greater than 10-15%. Calibration coefficients are then calculated through the hourly values of IWV provided by the co-located GPS. The comparison between the constants derived by GPS and Vaisala RS92 radiosondes launched at Maïdo during MALICCA, points out an acceptable agreement in terms of accuracy of the mean calibration value (with a difference of approximately 2-3%), but a significant difference in terms of variability (14 vs. 7-9%, for GPS and RS92 calibration procedures, respectively). We obtained a relatively good agreement between the lidar measurements and 15 co-located and simultaneous RS92 radiosondes. A relative difference below 10% is measured in low and middle troposphere (2-10 km). The upper troposphere (up to 15 km) is characterized by a larger spread (approximately 20%), because of the increasing distance between the two sensors. To measure water vapor in the UTLS region, nighttime and monthly water vapor profiles are presented and compared. The good agreement between the lidar monthly profile and the mean WVMR profile measured by satellite MLS has been used as a quality control procedure of the lidar product, attesting the absence of significant wet biases and validating the calibration procedure. Thanks to its performance and location, the MAIDO H2O lidar is devoted to become a reference instrument in the southern subtropics, allowing to insure the long-term survey of the vertical distribution of water vapor, and to document scientific themes such as stratosphere-troposphere exchange, tropospheric dynamics in the subtropics, links between cirrus clouds and water vapor.

Dionisi, D.; Keckhut, P.; Courcoux, Y.; Hauchecorne, A.; Porteneuve, J.; Baray, J. L.; Leclair de Bellevue, J.; Vérèmes, H.; Gabarrot, F.; Payen, G.; Decoupes, R.; Cammas, J. P.

2014-10-01

323

Long-range transport of aerosols from agriculture crop residue burning in Indo-Gangetic Plains—A study using LIDAR, ground measurements and satellite data  

NASA Astrophysics Data System (ADS)

Agriculture crop residue burning in tropics is an important source of atmospheric aerosols and monitoring their long-range transport is an important element in climate change studies. Synchronous measurements using micro-pulsed lidar, MICROTOPS-II sun photometer, multi-filter rotating shadow band radiometer (MFRSR) on aerosol optical depth and ground reaching solar irradiance were carried at an urban location in central region of India. Aerosol backscatter profiles obtained from micro-pulse lidar showed elevated aerosol layers up to ~3 km on certain days during October 2007. Satellite data observations on aerosol properties suggested transport of particles from agriculture crop residue burning in Indo-Gangetic Plains over large regions. Radiative forcing of aerosols estimated from SBDART model with input information on aerosol chemical properties, aerosol optical depth and single scattering albedo and broadband solar irradiance measurements using MFRSR showed good correlation (R=0.98).

Badarinath, K. V. S.; Kumar Kharol, Shailesh; Rani Sharma, Anu

2009-01-01

324

Active Raman sounding of the earth's water vapor field  

NASA Technical Reports Server (NTRS)

The typically weak cross-sections characteristic of Raman processes has historically limited their use in atmospheric remote sensing to nighttime application. However, with advances in instrumentation and techniques, it is now possible to apply Raman lidar to the monitoring of atmospheric water vapor, aerosols and clouds throughout the diurnal cycle. Upper tropospheric and lower stratospheric measurements of water vapor using Raman lidar are also possible but are limited to nighttime and require long integration times. However, boundary layer studies of water vapor variability can now be performed with high temporal and spatial resolution. This paper will review the current state-of-the-art of Raman lidar for high-resolution measurements of the atmospheric water vapor, aerosol and cloud fields. In particular, we describe the use of Raman lidar for mapping the vertical distribution and variability of atmospheric water vapor, aerosols and clouds throughout the evolution of dynamic meteorological events. The ability of Raman lidar to detect and characterize water in the region of the tropopause and the importance of high-altitude water vapor for climate-related studies and meteorological satellite performance are discussed.

Tratt, David M.; Whiteman, David N.; Demoz, Belay B.; Farley, Robert W.; Wessel, John E.

2005-01-01

325

Diffusion in the lower stratosphere as determined from lidar measurements of volcanic aerosol dispersion  

NASA Technical Reports Server (NTRS)

Lidar measurements of the stratospheric aerosol layer from the Fuego volcanic eruption in 1974 are analyzed to yield estimates of effective vertical mixing coefficients K(z). The data at 19 deg N latitude give K(z) = 6.6 x 10 to the 2nd sq cm/sec for the altitude range of 19 + or - 1.5 km, while the data at 37 deg N yield K(z) = 13 x 10 to the 2nd sq cm/sec for 19 + or - 3.5 km. The variability in these values is about a factor of 2. These derived K(z) values are interpreted as being due mainly to diffusion.

Remsberg, E. E.

1980-01-01

326

Design and development of micro pulse lidar for cloud and aerosol studies  

NASA Astrophysics Data System (ADS)

A micro pulse lidar (MPL) has been indigenously designed and developed at the National Physical Laboratory, New Delhi using a 532 nm, 500 pico second pulsed laser having average power of 50mW (at 7.5 KHz PRR). Photon counting technique has been incorporated using the conventional optics, multichannel scaler (Stanford Research Systems SR430) and high sensitive photomultiplier tube. The sensitivity, range and bin etc are computer controlled in the present system. The interfacing between MPL and computer has been achieved by serial (RS232) and parallel printer port. The necessary software and graphical user interface has been developed using visual basic. In addition to this the telescope cover status sensing circuit has been incorporated to avoid conflict between dark count and background acquisition. The micro pulse lidar will be used for the aerosol, boundary layer and the cloud studies at a bin resolution of 6 meters. In the present communication the details of the system and preliminary results will be presented.

Dubey, P. K.; Arya, B. C.; Ahammed, Y. Nazeer; Kumar, Arun; Kulkarni, P. S.; Jain, S. L.

2008-12-01

327

Measurements of aerosol phase function and vertical backscattering coefficient using a charge-coupled device side-scatter lidar.  

PubMed

By using a charge-coupled device (CCD) as the detector, side-scatter lidar has great potential applications in the near range atmospheric detection. A new inversion method is proposed for CCD side-scatter lidar (Clidar) to retrieve aerosol phase function and vertical backscattering coefficient. Case studies show the retrieved results from Clidar are in good agreements with those obtained from other instruments. It indicates that the new proposed inversion method is reliable and feasible and that the Clidar is practicable. PMID:24515072

Tao, Zongming; Liu, Dong; Wang, Zhenzhu; Ma, Xiaomin; Zhang, Qingze; Xie, Chenbo; Bo, Guangyu; Hu, Shunxing; Wang, Yingjian

2014-01-13

328

The evaluation of a shuttle borne lidar experiment to measure the global distribution of aerosols and their effect on the atmospheric heat budget  

NASA Technical Reports Server (NTRS)

A shuttle-borne lidar system is described, which will provide basic data about aerosol distributions for developing climatological models. Topics discussed include: (1) present knowledge of the physical characteristics of desert aerosols and the absorption characteristics of atmospheric gas, (2) radiative heating computations, and (3) general circulation models. The characteristics of a shuttle-borne radar are presented along with some laboratory studies which identify schemes that permit the implementation of a high spectral resolution lidar system.

Shipley, S. T.; Joseph, J. H.; Trauger, J. T.; Guetter, P. J.; Eloranta, E. W.; Lawler, J. E.; Wiscombe, W. J.; Odell, A. P.; Roesler, F. L.; Weinman, J. A.

1975-01-01

329

Mid-latitude cirrus classification at Rome Tor Vergata through a multi-channel Raman-Mie-Rayleigh lidar  

NASA Astrophysics Data System (ADS)

A methodology to identify and characterize cirrus clouds has been developed and applied to the multichannel-multiwavelength Rayleigh-Mie-Raman (RMR) lidar in Rome-Tor Vergata (RTV). A set of 167 cirrus cases, defined on the basis of quasi-stationary temporal period conditions, has been selected in a dataset consisting of about 500 h of nighttime lidar sessions acquired between February 2007 and April 2010. The derived lidar parameters (effective height, geometrical and optical thickness and mean back-scattering ratio) and the cirrus mid-height temperature (estimated from the radiosoundings of Pratica di Mare, WMO site #16245) of this sample have been analyzed by the means of a clustering multivariate analysis. This approach identified four cirrus classes above the RTV site: two thin cirrus clusters in mid and upper troposphere and two thick cirrus clusters in mid-upper troposphere. These results, which are very similar to those derived through the same approach in the lidar site of the Observatoire of Haute Provence (OHP), allows characterizing cirrus clouds over RTV site and attests the robustness of such classification. To have some indications about the cirrus generation methods for the different classes, the analyses of the extinction-to-backscatter ratio (lidar ratio, LReff), in terms of the frequency distribution functions and depending on the mid-height cirrus temperature have been performed. This study suggests that smaller (larger) ice crystals compose thin (thick) cirrus classes. This information, together with the value of relative humidity over ice (110 ± 30%), calculated through the simultaneous WV Raman measurements for the mid-tropospheric thin class, indicates that this class could be formed by an heterogeneous nucleation mechanism. The RTV cirrus results, re-computed through the cirrus classification by Sassen and Cho (1992), shows good agreement to other mid-latitude lidar cirrus observation for the relative occurrence of subvisible (SVC), thin and opaque cirrus classes (10%, 49% and 41%, respectively). The overall mean value of cirrus optical depth is 0.37 ± 0.18 , while most retrieved LReff values ranges between 10-60 sr and the estimated mean value is 31 ± 15 sr, similar to LR values of lower latitude cirrus measurements. The obtained results are consistent with previous studies conducted with different systems and confirm that cirrus classification based on a statistical approach seems to be a good tool both to validate the height-resolved cirrus fields, calculated by models, and to investigate the key processes governing cirrus formation and evolution. These are fundamental elements to improve the characterization of the cirrus optical properties and, thus, the determination of their radiative impact.

Dionisi, D.; Keckhut, P.; Liberti, G. L.; Cardillo, F.; Congeduti, F.

2013-04-01

330

Airborne and Ground-Based Measurements Using a High-Performance Raman Lidar. Part 2; Ground Based  

NASA Technical Reports Server (NTRS)

The same RASL hardware as described in part I was installed in a ground-based mobile trailer and used in a water vapor lidar intercomparison campaign, hosted at Table Mountain, CA, under the auspices of the Network for the Detection of Atmospheric Composition Change (NDACC). The converted RASL hardware demonstrated high sensitivity to lower stratospheric water vapor indicating that profiling water vapor at those altitudes with sufficient accuracy to monitor climate change is possible. The measurements from Table Mountain also were used to explain the reason, and correct , for sub-optimal airborne aerosol extinction performance during the flight campaign.

Whiteman, David N.; Cadirola, Martin; Venable, Demetrius; Connell, Rasheen; Rush, Kurt; Leblanc, Thierry; McDermid, Stuart

2009-01-01

331

The GAW Aerosol Lidar Observation Network (GALION) as a source of near-real time aerosol profile data for model evaluation and assimilation  

NASA Astrophysics Data System (ADS)

In 2007, the WMO Global Atmospheric Watch’s Science Advisory Group on Aerosols described a global network of lidar networks called GAW Aerosol Lidar Observation Network (GALION). GALION has a purpose of providing expanded coverage of aerosol observations for climate and air quality use. Comprised of networks in Asia (AD-NET), Europe (EARLINET and CIS-LINET), North America (CREST and CORALNET), South America (ALINE) and with contribution from global networks such as MPLNET and NDACC, the collaboration provides a unique capability to define aerosol profiles in the vertical. GALION is designed to supplement existing ground-based and column profiling (AERONET, PHOTONS, SKYNET, GAWPFR) stations. In September 2010, GALION held its second workshop and one component of discussion focussed how the network would integrate into model needs. GALION partners have contributed to the Sand and Dust Storm Warning and Analysis System (SDS-WAS) and to assimilation in models such as DREAM. This paper will present the conclusions of those discussions and how these observations can fit into a global model analysis framework. Questions of availability, latency, and aerosol parameters that might be ingested into models will be discussed. An example of where EARLINET and GALION have contributed in near-real time observations was the suite of measurements during the Eyjafjallajokull eruption in Iceland and its impact on European air travel. Lessons learned from this experience will be discussed.

Hoff, R. M.; Pappalardo, G.

2010-12-01

332

Photon-counting lidar for aerosol detection and 3D imaging  

NASA Astrophysics Data System (ADS)

Laser-based remote sensing is undergoing a remarkable advance due to novel technologies developed at MIT Lincoln Laboratory. We have conducted recent experiments that have demonstrated the utility of detecting and imaging low-density aerosol clouds. The Mobile Active Imaging LIDAR (MAIL) system uses a Lincoln Laboratory-developed microchip laser to transmit short pulses at 14-16 kHz Pulse Repetition Frequency (PRF), and a Lincoln Laboratory-developed 32x32 Geiger-mode Avalanche-Photodiode Detector (GmAPD) array for singlephoton counting and ranging. The microchip laser is a frequency-doubled passively Q-Switched Nd:YAG laser providing an average transmitted power of less than 64 milli-Watts. When the avalanche photo-diodes are operated in the Geiger-mode, they are reverse-biased above the breakdown voltage for a time that corresponds to the effective range-gate or range-window of interest. The time-of-flight, and therefore range, is determined from the measured laser transmit time and the digital time value from each pixel. The optical intensity of the received pulse is not measured because the GmAPD is saturated by the electron avalanche. Instead, the reflectivity of the scene, or relative density of aerosols in this case, is determined from the temporally and/or spatially analyzed detection statistics.

Marino, Richard M.; Richardson, Jonathan; Garnier, Robert; Ireland, David; Bickmeier, Laura; Siracusa, Christina; Quinn, Patrick

2009-05-01

333

Ground-based lidar measurements of ozone, water vapor, and aerosols in the lower stratosphere and troposphere  

SciTech Connect

Lidar measurements of ozone and water vapor concentrations were performed during several field experiments in 1980-1981 by means of the differential absorption laser technique. Profiles up to 26 km for ozone and up to 9 km for water vapor are presented. Also, a lidar survey of aerosol layers ranging from 12 to 23 km were performed following the Mt. St. Helens major eruption (May 1980). Experiments were conducted at the CNRS lidar facility of the Haute Provence Observatory which is located in southern France (44/sup 0/N, 5/sup 0/E). For ozone a vertical profile is recorded in three sequences, each requiring 15 min of acquisition time. The relative accuracy is better than 5% at the lower altitude and falls to 20% at 25 km. For water vapor the time sequences are 4 min or 8 min long and the accuracy is better than 10% in the lower troposphere.

Flamant, P.H. (Jet Propulsion Lab., Pasadena, CA; CNRS, Laboratoire de Meteorologie Dynamique, Palaiseau, Essonne, France); Pelon, J. (CNRS, Service d'Aeronomie, Verrieres-le-Buisson, Essonne, France); Lefrere, J. (Electricite de France, Direction des Etudes et Recherches, Chatou, Yvelines, France)

1982-01-01

334

Remote sensing of water vapour from the synergy of Raman lidar, GPS and in-situ observations during the DEMEVAP 2011 campaign  

NASA Astrophysics Data System (ADS)

The DEMEVAP (DEvelopment of MEthods for remote sensing of water VAPor) project aims at developing improved reference humidity sounding methods based on the combined used of scanning Raman lidars, ground-based sensors and GPS. The goal is to achieve absolute accuracy better than 3% on the column integrated water vapour (IWV). An intensive observing period was conducted in September-October 2011 at Observatoire de Haute Provence (OHP), France, with the aim of intercomparing several different techniques and instruments. It involved two Raman lidars, four radiosonde measurement systems, five GPS stations, a stellar spectrometer, and several ground-based capacitive and dew-point sensors. Observations were collected over 17 nights during which 26 balloons were released which carried a total of 79 radiosondes. Most of the balloons carried 3 or 4 different sonde types simultaneously (Vaisala RS92, MODEM M2K2-DC and M10, and Meteolabor Snow-White). The comparison of IWV measurements from the four radiosonde types to GPS reveals biases of -11% to +7%. Comparison of water vapour profiles from the radiosondes to the IGN scanning Raman lidar profiles reveals mostly dry and wet biases in the radiosondes data in dry layers in the middle and upper troposphere. Several Raman lidar calibration methods are evaluated which adjust the lidar measurements either on ground-based capacitive or dew-point sensors measurements, on radiosonde data or on GPS PWV data. Another method adjusts the lidar calibration constant as an extra parameter during GPS processing. All these methods show a good degree of consistency and yield a repeatability of 2 to 5% during the first 3-week period of the experiment. A drift in the calibration constant is observed throughout the full time of the experiment which is partly explained by a temperature-dependent bias in the lidar measurements induced by the progressive cooling of the atmosphere. Modelling and correcting this effect or modifying the Raman lidar detection system should allow achieving a 3% level of accuracy into the long term and make the Raman lidar technique suitable to detect biases or to calibrate data from other techniques (e.g., radiosondes, visible spectrometers and microwave radiometers).

Bock, Olivier; David, Leslie; Bosser, Pierre; Thom, Christian; Pelon, Jacques; Keckhut, Philippe; Sarkissian, Alain; Bourcy, Thomas; Tzanos, Diane; Tournois, Guy

2013-04-01

335

Correction technique for Raman water vapor lidar signal-dependent bias and suitability for water vapor trend monitoring in the upper troposphere  

NASA Astrophysics Data System (ADS)

The MOHAVE-2009 campaign brought together diverse instrumentation for measuring atmospheric water vapor. We report on the participation of the ALVICE (Atmospheric Laboratory for Validation, Interagency Collaboration and Education) mobile laboratory in the MOHAVE-2009 campaign. In appendices we also report on the performance of the corrected Vaisala RS92 radiosonde measurements during the campaign, on a new radiosonde based calibration algorithm that reduces the influence of atmospheric variability on the derived calibration constant, and on other results of the ALVICE deployment. The MOHAVE-2009 campaign permitted the Raman lidar systems participating to discover and address measurement biases in the upper troposphere and lower stratosphere. The ALVICE lidar system was found to possess a wet bias which was attributed to fluorescence of insect material that was deposited on the telescope early in the mission. Other sources of wet biases are discussed and data from other Raman lidar systems are investigated, revealing that wet biases in upper tropospheric (UT) and lower stratospheric (LS) water vapor measurements appear to be quite common in Raman lidar systems. Lower stratospheric climatology of water vapor is investigated both as a means to check for the existence of these wet biases in Raman lidar data and as a source of correction for the bias. A correction technique is derived and applied to the ALVICE lidar water vapor profiles. Good agreement is found between corrected ALVICE lidar measurments and those of RS92, frost point hygrometer and total column water. The correction is offered as a general method to both quality control Raman water vapor lidar data and to correct those data that have signal-dependent bias. The influence of the correction is shown to be small at regions in the upper troposphere where recent work indicates detection of trends in atmospheric water vapor may be most robust. The correction shown here holds promise for permitting useful upper tropospheric water vapor profiles to be consistently measured by Raman lidar within NDACC (Network for the Detection of Atmospheric Composition Change) and elsewhere, despite the prevalence of instrumental and atmospheric effects that can contaminate the very low signal to noise measurements in the UT.

Whiteman, D. N.; Cadirola, M.; Venable, D.; Calhoun, M.; Miloshevich, L.; Vermeesch, K.; Twigg, L.; Dirisu, A.; Hurst, D.; Hall, E.; Jordan, A.; Vömel, H.

2012-11-01

336

Combining data from lidar and in situ instruments to characterize the vertical structure of aerosol optical properties  

NASA Technical Reports Server (NTRS)

Over the last decade, the quantification of tropospheric aerosol abundance, composition and radiative impacts has become an important research endeavor. For the most part, the interest in tropospheric aerosols is derived from questions related to the global and local (instantaneous) radiative forcing of climate due to these aerosols. One approach is to study local forcing under well-defined conditions, and to extrapolate such results to global scales. To estimate local aerosol forcing, appropriate radiative transfer models can be employed (e.g., the Fu-Liou radiative transfer code, [Fu and Liou, 1993]). In general, such models require information on derived aerosol properties [Toon, 1994]; namely the aerosol optical depth, single-scattering albedo, and asymmetry factor (phase function), all of which appear in the equations of radiative transfer. In this paper, we report on a method that utilizes lidar data and in situ aerosol size distribution measurements to deduce the vertical structure of the aerosol complex index of refraction in the near IR, thus identifying the aerosol type. Together with aerosol size distributions obtained in situ, the aerosol refractive index can be used to calculate the necessary derived aerosol properties. The data analyzed here were collected during NASA's PEM West-B (Pacific Exploratory Mission) experiment, which took place in February/March 1994. The platform for the measurements was the NASA DC-8 aircraft. The primary goal of the PEM West missions [Browell et al., 1996] was the assessment of potential anthropogenic perturbations of the chemistry in the Pacific Basin troposphere. For this purpose the timing of PEM West-B corresponded to the seasonal peak in transport from the Asian continent into the Pacific basin [Merrill et al., in press]. This period normally occurs during Northern Hemisphere spring, when the Japan jet is well developed.

Redemann, J.; Turco, R. P.; Pueschel, R. F.; Browell, E. V.; Grant, W. B.

1998-01-01

337

Comparing Simultaneous Stratospheric Aerosol and Ozone Lidar Measurements with SAGE 2 Data after the Mount Pinatubo Eruption  

NASA Technical Reports Server (NTRS)

Stratospheric aerosol and ozone profiles obtained simultaneously from the lidar station at the University of L'Aquila (42.35 deg N, 13.33 deg E, 683 m above sea level) during the first 6 months following the eruption of Mount Pinatubo are compared with corresponding nearby Stratospheric Aerosol and Gas Experiment (SAGE) 2 profiles. The agreement between the two data sets is found to be reasonably good. The temporal change of aerosol profiles obtained by both techniques showed the intrusion and growth of Pinatubo aerosols. In addition, ozone concentration profiles derived from an empirical time-series model based on SAGE 2 ozone data obtained before the Pinatubo eruption are compared with measured profiles. Good agreement is shown in the 1991 profiles, but ozone concentrations measured in January 1992 were reduced relative to time-series model estimates. Possible reasons for the differences between measured and model-based ozone profiles are discussed.

Yue, G. K.; Poole, L. R.; McCormick, M. P.; Veiga, R. E.; Wang, P.-H.; Rizi, V.; Masci, F.; DAltorio, A.; Visconti, G.

1995-01-01

338

Lidar Ratios for Dust Aerosols Derived From Retrievals of CALIPSO Visible Extinction Profiles Constrained by Optical Depths from MODIS-Aqua and CALIPSO/CloudSat Ocean Surface Reflectance Measurements  

NASA Technical Reports Server (NTRS)

CALIPSO's (Cloud Aerosol Lidar Infrared Pathfinder Satellite Observations) analysis algorithms generally require the use of tabulated values of the lidar ratio in order to retrieve aerosol extinction and optical depth from measured profiles of attenuated backscatter. However, for any given time or location, the lidar ratio for a given aerosol type can differ from the tabulated value. To gain some insight as to the extent of the variability, we here calculate the lidar ratio for dust aerosols using aerosol optical depth constraints from two sources. Daytime measurements are constrained using Level 2, Collection 5, 550-nm aerosol optical depth measurements made over the ocean by the MODIS (Moderate Resolution Imaging Spectroradiometer) on board the Aqua satellite, which flies in formation with CALIPSO. We also retrieve lidar ratios from night-time profiles constrained by aerosol column optical depths obtained by analysis of CALIPSO and CloudSat backscatter signals from the ocean surface.

Young, Stuart A.; Josset, Damien B.; Vaughan, Mark A.

2010-01-01

339

Evolution of the Pinatubo volcanic aerosol column above Pasadena, California observed with a mid-infrared backscatter lidar  

NASA Technical Reports Server (NTRS)

The evolution of the volcanic debris plume originating from the June 1991 eruption of Mt. Pinatubo has been monitored since its genesis using a ground-based backscatter lidar facility sited at the Jet Propulsion Laboratory (JPL). Both absolute and relative pre- and post-Pinatubo backscatter observations are in accord with Mie scattering projections based on measured aerosol particle size distributions reported in the literature. The post-Pinatubo column-integrated backscatter coefficient peaked approximately 400 days after the eruption, and the observed upper boundary of the aerosol column subsided at a rate of approximately 200 m/mon.

Tratt, David M.; Menzies, Robert T.

1995-01-01

340

Evolution of the Pinatubo volcanic aerosol column above Pasadena, California observed with a mid-infrared backscatter lidar  

SciTech Connect

The evolution of the volcanic debris plume originating from the June 1991 eruption of Mt. Pinatubo has been monitored since its genesis using a ground-based backscatter lidar facility sited at the Jet Propulsion Laboratory (JPL). Both absolute and relative pre- and post-Pinatubo backscatter observations are in accord with Mie scattering projections based on measured aerosol particle size distributions reported in the literature. The post-Pinatubo column-integrated backscatter coefficient peaked approximately 400 days after the eruption, and the observed upper boundary of the aerosol column subsided at a rate of {approximately}200 m mon{sup {minus}1}. 20 refs., 4 figs., 2 tabs.

Tratt, D.M.; Menzies, R.T. [California Institute of Technology, Pasadena, CA (United States)] [California Institute of Technology, Pasadena, CA (United States)

1995-04-01

341

Multi-wavelength Airborne High Spectral Resolution Lidar Observations of Aerosol Above Clouds in California during DISCOVER-AQ  

NASA Astrophysics Data System (ADS)

Accurately representing the vertical profile of aerosols is important for determining their radiative impact, which is still one of the biggest uncertainties in climate forcing. Aerosol radiative forcing can be either positive or negative depending on aerosol absorption properties and underlying albedo. Therefore, accurately characterizing the vertical distribution of aerosols, and specifically aerosols above clouds, is vital to understanding climate change. Unlike passive sensors, airborne lidar has the capability to make vertically resolved aerosol measurements of aerosols above and between clouds. Recently, NASA Langley Research Center has built and deployed the world's first airborne multi-wavelength High Spectral Resolution Lidar, HSRL-2. The HSRL-2 instrument employs the HSRL technique to measure extinction at both 355 nm and 532 nm and also measures aerosol depolarization and backscatter at 355 nm, 532 nm and 1064 nm. Additional HSRL-2 data products include aerosol type and range-resolved aerosol microphysical parameters (e.g., effective radius, number concentration, and single scattering albedo). HSRL-2 was deployed in the San Joaquin Valley, California, from January 16 to February 6, 2013, on the DISCOVER-AQ field campaign (Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality). On February 6, the observation region was mostly cloudy, and HSRL-2 saw two distinct aerosol layers above the clouds. One layer was aged boundary-layer pollution located just above cloud top at approximately 1.5 km above sea level. An aged smoke layer was also observed over land and over the ocean at altitudes 4-7 km ASL. In this study, we will show HSRL-2 products for these cases, and compare them with airborne in situ measurements of the 1.5-km layer from a coincident flight of the NASA P3B. We will also compare and contrast the HSRL-2 measurements of these two aerosol layers with each other and the clear-air boundary layer observed on other dates during DISCOVER-AQ. In addition, we will discuss scaling this measurement technique to satellite applications such as the Aerosols-Clouds-Ecosystems mission.

Hostetler, C. A.; Burton, S. P.; Ferrare, R. A.; Rogers, R. R.; Mueller, D.; Chemyakin, E.; Cook, A. L.; Harper, D. B.; Ziemba, L. D.; Beyersdorf, A. J.; Anderson, B. E.

2013-12-01

342

Study of the Properties of Aerosols and the Air Quality Index Using a Backscatter Lidar System and Aeronet Sunphotometer in the City of São Paulo, Brazil  

Microsoft Academic Search

Between the months of July and September of 2007 during the so-called Brazilian dry season, an aerosol profiling campaign was carried out with a backscatter(ing) lidar system in the city of São Paulo, Brazil. The main goal of this campaign was to observe the aerosol load in the troposphere (up to 10 km) and its daily behavior to check for

Eduardo Landulfo; Fábio J. S. Lopes; Glauber L. Mariano; Ani S. Torres; Wellington C. de Jesus; Walter M. Nakaema; Maria P. P. M. Jorge; Rauda Mariani; Klara Slezakova; Dionísia Castro; Maria Pereira; Simone Morais; Cristina Delerue-Matos; Maria Alvim-Ferraz; Catherine Barton; Charles Zarzecki; Mark Russell; Marjaleena Aatamila; Pia Verkasalo; Maarit Korhonen; Marja Viluksela; Kari Pasanen; Pekka Tiittanen; Aino Nevalainen; Li Rong; Peter Nielsen; Guoqiang Zhang; Yi-Ming Kuo; Juu-En Chang; Kun-Yu Chang; Chih-C. Chao; Yeu-Juin Tuan; Guo-Ping Chang-Chien; Yongping Li; Guohe Huang; Arhontoula Chatzilazarou; Evangelos Katsoyannos; Olga Gortzi; Stavros Lalas; Yiannis Paraskevopoulos; Euthalia Dourtoglou; John Tsaknis; Tarek Abichou; Jeremy Clark; Sze Tan; Jeffery Chanton; Gary Hater; Roger Green; Doug Goldsmith; Morton Barlaz; Nathan Swan; Gang Sun; Huiqing Guo; Jonathan Peterson; Zhengmin Qian; Hung-Mo Lin; Walter Stewart; Nirav Shah; Linli Kong; Fen Xu; Denjin Zhou; Zhicao Zhu; Qingci He; Shengwen Liang; Weiqing Chen; Chungsying Lu; Hsunling Bai; Fengsheng Su; Wenfa Chen; Jyh Hwang; Hsiu-Hsia Lee; Judith Chow; John Watson; Douglas Lowenthal; Lung-Wen Chen; Nehzat Motallebi

2010-01-01

343

High Spectral Resolution LIDAR Receivers to measure Aerosol to Molecular Scattering Ratio in Bistatic mode for use in Atmospheric Monitoring for EAS Detectors  

Microsoft Academic Search

We present the design of a bistatic High Spectral Resolution Lidar (HSRL) aiming at measuring the aerosol phase function for applications in Ultra High Energy Cosmic Ray experiments. The expectation is to give accurate data for the aerosol phase function, needed to correct the Extended Air Shower (EAS) signal of air-fluorescence detectors for the air Cherenkov contamination, caused mainly by

E. Fokitis; S. Maltezos; A. Papayannis; P. Fetfatzis; A. Georgakopoulou; A. Aravantinos

2009-01-01

344

Theory of CW lidar aerosol backscatter measurements and development of a 2.1 microns solid-state pulsed laser radar for aerosol backscatter profiling  

NASA Technical Reports Server (NTRS)

The performance and calibration of a focused, continuous wave, coherent detection CO2 lidar operated for the measurement of atmospheric backscatter coefficient, B(m), was examined. This instrument functions by transmitting infrared (10 micron) light into the atmosphere and collecting the light which is scattered in the rearward direction. Two distinct modes of operation were considered. In volume mode, the scattered light energy from many aerosols is detected simultaneously, whereas in the single particle mode (SPM), the scattered light energy from a single aerosol is detected. The analysis considered possible sources of error for each of these two cases, and also considered the conditions where each technique would have superior performance. The analysis showed that, within reasonable assumptions, the value of B(m) could be accurately measured by either the VM or the SPM method. The understanding of the theory developed during the analysis was also applied to a pulsed CO2 lidar. Preliminary results of field testing of a solid state 2 micron lidar using a CW oscillator is included.

Kavaya, Michael J.; Henderson, Sammy W.; Frehlich, R. G.

1991-01-01

345

Vertical Profiles of Aerosol Parameters from Inversion of Airborne Multiwavelength High-Spectral-Resolution Lidar Data During TCAP  

NASA Astrophysics Data System (ADS)

The first intensive observational period of the Two-Column Aerosol Project (TCAP) field campaign was carried out on Cape Cod, Massachusetts from 7 - 29 July 2012. The ARM Mobile Facility (AMF) and the Mobile Aerosol Observing System (MAOS) measured aerosol properties, radiation, and cloud characteristics on Cape Cod. Two aircraft were deployed during the intensive observational period. The first aircraft was equipped with a suite of in situ instrumentation to provide measurements of aerosol optical properties, particle composition and direct-beam irradiance. The second aircraft flew directly over the first aircraft. This second aircraft flew the world's first airborne 3 backscatter - 2 extinction High-Spectral-Resolution Lidar (HSRL) and a Research Scanning Polarimeter (RSP) to provide continuous aerosol and cloud properties in the column below. The multiwavelength HSRL was built and deployed by NASA Langley Research Center. The RSP was developed by NASA GISS. The measurements were characterized by periods of comparatively high optical depth resulting from the transport of polluted air out over the North Atlantic Ocean. Urban haze was advected from the east coast of the US and Canada. Forest fires in Canada likely injected smoke into the air which was detected by the lidar system after a comparably short transport time of one or two days. In this contribution we present for the first time vertical profiles of aerosol optical and microphysical properties inferred from a newly developed automated and unsupervised data inversion algorithm. This algorithm processes the profiles of the backscatter and extinction coefficients measured with this novel multiwavelength HSRL. The lidar system provides us with the measured optical extensive properties, i.e. particle backscatter coefficients at 355, 532, and 1064 nm and extinction coefficients at 355 and 532 nm (i.e. '3+2'). From the extinction and backscatter coefficients we obtain the particle intensive properties, i.e., extinction-to-backscatter (lidar) ratios, backscatter-related Angstrom exponents and extinction-related Angstrom exponents. The depolarization ratio is measured at 532 nm. The inversion of the profiles of the optical data provides us with profiles of particle effective radius and integral properties of the particle size distribution (number, surface-area and volume concentration) and complex refractive index. From this information we compute additional optical properties, e.g. profiles of single-scattering albedo, scattering and absorption. We present initial results of these parameters retrievals for some of the pollution cases observed during TCAP.

Mueller, D.; Chemyakin, E.; Hostetler, C. A.; Ferrare, R. A.; Hair, J. W.; Cook, A. L.; Harper, D. B.; Mack, T. L.; Hare, R. J.; Cleckner, C. S.; Rogers, R.; Obland, M. D.; Burton, S. P.; Scarino, A. J.; Cairns, B.; Ottaviani, M.; Russell, P. B.; Schmid, B.; Fast, J. D.; Berg, L. K.

2012-12-01

346

Aerosol disturbances of the stratosphere over Tomsk according to data of lidar observations in volcanic activity period 2006-2011  

NASA Astrophysics Data System (ADS)

We summarize and analyze the lidar measurements (Tomsk: 56.5°N; 85.0°E) of the optical characteristics of the stratospheric aerosol layer (SAL) in the volcanic activity period 2006-2011. The background SAL state with minimal aerosol content, which was observed since 1997 under the conditions of long-term volcanically quiescent period, was interrupted in October 2006 by a series of explosive eruptions of volcanoes of the Pacific Ring of Fire: Rabaul (October 2006, New Guinea); Okmok and Kasatochi (July-August 2008, Aleutian Islands); Redoubt (March-April 2009, Alaska); Sarychev Peak (June 2009, Kuril Islands), and Grimsvötn (May 2011, Iceland). A short-term and minor disturbance of the lower stratosphere was also observed in April 2010 after eruption of the Icelandic volcano Eyjafjallajokull. The developed regional empirical model of the vertical distribution of background SAL optical characteristics was used to identify the periods of elevated stratospheric aerosol content after each of the volcanic eruptions.

Makeev, Andrey P.; Burlakov, Vladimir D.; Dolgii, Sergey I.; Nevzorov, Aleksey V.; Trifonov, Dimitar A.

2012-11-01

347

Airborne differential absorption lidar system for measurements of atmospheric water vapor and aerosols  

NASA Technical Reports Server (NTRS)

An airborne differential absorption lidar (DIAL) system has been developed at the NASA Langley Research Center for remote measurements of atmospheric water vapor (H2O) and aerosols. A solid-state alexandrite laser with a 1-pm linewidth and greater than 99.85% spectral purity was used as the on-line transmitter. Solid-state avalanche photodiode detector technology has replaced photomultiplier tubes in the receiver system, providing an average increase by a factor of 1.5-2.5 in the signal-to-noise ratio of the H2O measurement. By incorporating advanced diagnostic and data-acquisition instrumentation into other subsystems, we achieved additional improvements in system operational reliability and measurement accuracy. Laboratory spectroscopic measurements of H2O absorption-line parameters were performed to reduce the uncertainties in our knowledge of the absorption cross sections. Line-center H2O absorption cross sections were determined, with errors of 3-6%, for more than 120 lines in the 720-nm region. Flight tests of the system were conducted during 1989-1991 on the NASA Wallops Flight Facility Electra aircraft, and extensive intercomparison measurements were performed with dew-point hygrometers and H2O radiosondes. The H2O distributions measured with the DIAL system differed by less than 10% from the profiles determined with the in situ probes in a variety of atmospheric conditions.

Carter, Arlen F.; Allen, Robert J.; Mayo, M. Neale; Butler, Carolyn F.; Grossman, Benoist E.; Ismail, Syed; Grant, William B.; Browell, Edward V.; Higdon, Noah S.; Mayor, Shane D.; Ponsardin, Patrick; Hueser, Alene W.

1994-01-01

348

Increase in background stratospheric aerosol observed with lidar at Mauna Loa Observatory and Boulder, Colorado - article no. L15808  

SciTech Connect

The stratospheric aerosol layer has been monitored with lidars at Mauna Loa Observatory in Hawaii and Boulder in Colorado since 1975 and 2000, respectively. Following the Pinatubo volcanic eruption in June 1991, the global stratosphere has not been perturbed by a major volcanic eruption providing an unprecedented opportunity to study the background aerosol. Since about 2000, an increase of 4-7% per year in the aerosol backscatter in the altitude range 20-30 km has been detected at both Mauna Loa and Boulder. This increase is superimposed on a seasonal cycle with a winter maximum that is modulated by the quasi-biennial oscillation (QBO) in tropical winds. Of the three major causes for a stratospheric aerosol increase: volcanic emissions to the stratosphere, increased tropical upwelling, and an increase in anthropogenic sulfur gas emissions in the troposphere, it appears that a large increase in coal burning since 2002, mainly in China, is the likely source of sulfur dioxide that ultimately ends up as the sulfate aerosol responsible for the increased backscatter from the stratospheric aerosol layer. The results are consistent with 0.6-0.8% of tropospheric sulfur entering the stratosphere.

Hofmann, D.; Barnes, J.; O'Neill, M.; Trudeau, M.; Neely, R. [NOAA, Boulder, CO (United States)

2009-08-15

349

Comparison of upper tropospheric water vapor from GOES, Raman lidar, and Cross-chain Loran Atmospheric Sounding System measurements  

NASA Technical Reports Server (NTRS)

Observations of upper tropospheric relative humidity obtained from Raman lidar and Cross-chain Loran Atmospheric Sounding System (CLASS) sonde instruments obtained during the First ISCCP Regional Experiment (FIRE) Cirrus-II field program are compared with satellite measurements from the GOES 6.7-micron channel. The 6.7-micron channel is sensitive to water vapor integrated over a broad layer in the upper troposphere (roughly 500-200 mbar). Instantaneous measurements of the upper tropospheric relative humidity from GOES are shown to agree to within roughly 6% of the nearest lidar observations and 9% of the nearest CLASS observations. The CLASS data exhibit a slight yet systematic dry bias in upper tropospheric humidity, a result which is consistent with previous radiosonde intercomparisons. Temporal stratification of the CLASS data indicates that the magnitude of the bias is dependent upon the time of day, suggesting a solar heating effect in the radiosonde sensor. Using CLASS profiles, the impact of vertical variability in relative humidity upon the GOES upper tropospheric humidity measurements is also examined. The upper tropospheric humidity inferred from the GOES 6.7-micron channel is demonstrated to agree to within roughly 5% of the relative humidity vertically averaged over the depth of atmosphere to which the 6.7-micron channel is sensitive. The results of this study encourage the use of satellite measurements in the 6.7-micron channel to quantitatively describe the distribution and temporal evolution of the upper tropospheric humidity field.

Soden, B. J.; Ackerman, S. A.; Starr, D. O'C.; Melfi, S. H.; Ferrare, R. A.

1994-01-01

350

Estimation of spatially distributed latent energy flux over complex terrain using a scanning water-vapor Raman lidar  

SciTech Connect

Evapotranspiration is one of the critical variables in both water and energy balance models of the hydrological system. The hydrologic system is driven by the soil-plant-atmosphere continuum, and as such is a spatially distributed process. Traditional techniques rely on point sensors to collect information that is then averaged over a region. The assumptions involved in spatially average point data is of limited value (1) because of limited sensors in the arrays, (2) the inability to extend and interpret the Measured scalars and estimated fluxes at a point over large areas in complex terrain, and (3) the limited understanding of the relationship between point measurements of spatial processes. Remote sensing technology offers the ability to collect detailed spatially distributed data. However, the Los Alamos National Laboratory`s volume-imaging, scanning water-vapor Raman lidar has been shown to be able to estimate the latent energy flux at a point. The extension of this capability to larger scales over complex terrain represents a step forward. This abstract Outlines the techniques used to estimate the spatially resolved latent energy flux. The following sections describe the site, model, data acquired, and lidar estimated latent energy ``map``.

Cooper, D.I.; Eichinger, W.; Archuleta, J.; Cottingame, W.; Osborne, M.; Tellier, L.

1995-09-01

351

Midlatitude lidar backscatter to mass, area, and extinction conversion model based on in situ aerosol measurements from 1980 to 1987.  

PubMed

Balloonborne particle counter data from Laramie, WY are used to define a seasonally averaged stratospheric sulfuric acid aerosol size distribution in three altitude intervals from 15 to 30 km for the 1980-1987 period. This period includes the volcanic eruptions of Mt. St. Helens, Alaid, Nyamuragira, El Chichon, and Nevado el Ruiz and begins and ends at what are believed to be periods of near background (nonvolcanic) stratospheric conditions. The size distributions are used to calculate lidar backscatter to extinction, mass, and area ratios for an appropriate range of particle indices of refraction. These ratios may then be used to infer particle extinction, mass, and area from midlatitude lidar data for this time period. PMID:20581956

Jäger, H; Hofmann, D

1991-01-01

352

Lidar Observation of Aerosol and Temperature Stratification over Urban Area During the Formation of a Stable Atmospheric PBL  

NASA Technical Reports Server (NTRS)

In recent years, the processes in the atmospheric planetary boundary layer (PBL) over urban areas were intensely investigated, due to ecological problems related to the air, soil, and water pollution. New pollution sources in new residential districts, when in contradiction to the microclimate and topography requirements of that region, create a number of considerable hazards and problems. The present study is a continuation of our preceding investigations and aims at revealing the aerosol structure and stratification during the transition after sunset as measured by two lidars. Such observation of the nocturnal, stable PBL formation over an urban area in Bulgaria has not been reported before. The lidars' high time and spatial resolutions allow the changes of the internal structure of the PBL's part located above the surface layer to be observed.

Kolev, I.; Parvanov, O.; Kaprielov, B.; Mitev, V.; Simeonov, V.; Grigorov, I.

1992-01-01

353

Comparative lidar study of the optical, geometrical, and dynamical properties of stratospheric post-volcanic aerosols, following the eruptions of El Chichon and Mount Pinatubo  

Microsoft Academic Search

The spatiotemporal evolution of aerosols formed from precursors injected into the stratosphere by major volcanic eruptions, such as those of El Chichon in 1982 and Mount Pinatubo in 1991, has been studied using a ground-based lidar system located at the Observatoire de Haute-Provence (OHP) in southern France (44°N, 5°E). From the inversion of the lidar signals the optical, geometrical, and

P. Chazette; C. David; J. Lefrère; S. Godin; J. Pelon; G. Mégie

1995-01-01

354

A 1000 Hz Pulsed Solid-State Raman Laser for Coherent Lidar Measurement of Wake Vortices  

NASA Technical Reports Server (NTRS)

Included in the overview is a discussion of the 1.5 micron laser specifications, eye safety and cost, scan rates, pulselength, range capability issues, Raman beam cleanup, receiver layout, and the real-time processor and display.

Koch, Grady J.; Murray, James; Lytle, Carroll; Nguyen, Chi

1997-01-01

355

Sun photometer and lidar measurements of the plume from the Hawaii Kilauea Volcano Pu'u O'o vent: Aerosol flux and SO2 lifetime  

USGS Publications Warehouse

Aerosol optical depths and lidar measurements were obtained under the plume of Hawaii Kilauea Volcano on August 17, 2001, ???9 km downwind from the erupting Pu'u O'o vent. Measured aerosol optical depths (at 500 nm) were between 0.2-0.4. Aerosol size distributions inverted from the spectral sun photometer measurements suggest the volcanic aerosol is present in the accumulation mode (0.1-0.5 micron diameter), which is consistent with past in situ optical counter measurements. The aerosol dry mass flux rate was calculated to be 53 Mg d-1. The estimated SO2 emission rate during the aerosol measurements was ???1450 Mg d-1. Assuming the sulfur emissions at Pu'u O'o vent are mainly SO2 (not aerosol), this corresponds to a SO2 half-life of 6.0 hours in the atmosphere.

Porter, J.N.; Horton, K.A.; Mouginis-Mark, P. J.; Lienert, B.; Sharma, S.K.; Lau, E.; Sutton, A.J.; Elias, T.; Oppenheimer, C.

2002-01-01

356

Satellite and correlative measurements of the stratospheric aerosol. II Comparison of measurements made by SAM II, dustsondes and airborne lidar  

NASA Technical Reports Server (NTRS)

Results are shown from the first set of measurements conducted to validate extinction data from the Stratospheric Aerosol Measurement II (SAM II). Dustsonde-measured number density profiles and lidar-measured backscattering profiles for two days are converted to extinction profiles, and are shown to agree within their respective uncertainties at all heights above the tropopause. Near the tropopause, agreement depends on use of model size distributions with larger particles, having radii greater than 0.6 microns. The presence of such large particles is supported by measurements made elsewhere, is suggested by the in situ size distribution measurements reported, and is likely to have an important bearing on the radiative impact of the total stratospheric aerosol. It is concluded that the SAM II extinction data and uncertainty estimates are supported.

Russell, P. B.; Livingston, J. M.; Mccormick, M. P.; Chu, W. P.; Fuller, W. H.; Mcmaster, L. R.; Woods, D. C.; Swissler, T. J.; Rosen, J. M.; Hofmann, D. J.

1981-01-01

357

LIDAR measurements of the vertical aerosol profile and optical depth during the ACE-Asia 2001 IOP, at Gosan, Jeju Island, Korea.  

PubMed

In order to investigate the characteristic of optical properties of Asian dust particles, the atmospheric aerosol vertical profile was measured with the multi-wavelength LIDAR system, at the Gosan super site (33 degrees 17'N, 126 degrees 10'E) in Jeju Island, Korea, during the ACE-Asia intensive observation period, 11 March-4 May 2001. An air mass backward trajectory analysis, using Hysplit-4, was carried out to track the aerosol plume, with high mass loading, from the Chinese desert regions during the period of Asian dust storm events. Vertical atmospheric aerosol profiles on three major Asian dust storm event days, 22 March and 13 and 26 April 2001, have been analyzed. The LIDAR-derived aerosol optical depth values were compared with those measured by a collocated sunphotometer. PMID:15038535

Hong, Chun S; Lee, Kwon H; Kim, Young J; Iwasaka, Yasunobu

2004-03-01

358

Optical and microphysical properties of severe haze and smoke aerosol measured by integrated remote sensing techniques in Gwangju, Korea  

E-print Network

Optical and microphysical properties of severe haze and smoke aerosol measured by integrated remote October 2008 Accepted 21 October 2008 Keywords: Haze Raman lidar Satellite Single-scattering albedo a b s t r a c t Aerosol optical and microphysical parameters from severe haze events observed in October

Li, Zhanqing

359

Using Combined 532 NM HSRL and 1064 NM Elastic-Scatter Lidar Observations to Verify and Update CRAM Dual-Wavelength Aerosol Retrieval Models  

Microsoft Academic Search

The widely employed Fernald lidar equation solution relation retrieves aerosol backscatter versus height for an assumed aerosol extinction-to-backscatter ratio, Sa, and known system calibration factor, C, at a given wavelength, subject to the constraint\\/assumption that Sa is spatially constant over the solution layer (height range). At 532 nm, the calibration factor may be estimated fairly accurately by Rayleigh (molecular) normalization

John A. Reagan; Christopher J. McPherson; Richard Ferrare; Chris Hostetler; Johnathan Hair

2008-01-01

360

Comparison of IASI water vapor retrieval with H2O-Raman lidar in the frame of the Mediterranean HyMeX and ChArMEx programs  

NASA Astrophysics Data System (ADS)

The Infrared Atmospheric Sounding Interferometer (IASI) is a spaceborne passive sensor of new generation mainly dedicated to meteorological applications. Operational Level-2 products are available via the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT) since several years. In particular, vertical profiles of water vapor measurements are retrieved from infrared radiances at the global scale. Nevertheless, the robustness of such products has to be checked because only few validations have been reported. For this purpose, the field experiments that were held during the HyMeX and ChArMEx international programs are a very good opportunity. A H2O-Raman lidar was deployed on the Balearic Island of Menorca and operated continuously during ~6 and ~3 weeks during fall 2012 (Hydrological cycle in the Mediterranean eXperiment -HyMeX-) and summer 2013 (Chemistry-Aerosol Mediterranean Experiment -ChArMEx-), respectively. It measured simultaneously the water vapor mixing ratio and aerosol optical properties. This article does not aim to describe the IASI operational H2O inversion algorithm, but to compare the vertical profiles derived from IASI onboard MetOp-A and the ground-based lidar measurements to assess the reliability of the IASI operational product for the water vapor retrieval in both the lower and middle troposphere. The links between water vapor contents and both the aerosol vertical profiles and the air mass origins are also studied. About 30 simultaneous observations, performed during nighttime in cloud free conditions, have been considered. For altitudes ranging from 2 to 7 km, root mean square errors (correlation) of ˜ 0.5 g kg-1 (~0.77) and ~1.1 g kg-1 (~0.72) are derived between the operational IASI product and the available lidar profiles during HyMeX and ChArMEx, respectively. The values of both root mean square error and correlation are meaningful and show that the operational Level-2 product of the IASI-derived vertical water vapor mixing ratio can be considered for meteorological and climatic applications, at least in the frame of field campaigns.

Chazette, P.; Marnas, F.; Totems, J.

2014-06-01

361

Comparison of IASI water vapor retrieval with H2O-Raman lidar in the framework of the Mediterranean HyMeX and ChArMEx programs  

NASA Astrophysics Data System (ADS)

The Infrared Atmospheric Sounding Interferometer (IASI) is a new generation spaceborne passive sensor mainly dedicated to meteorological applications. Operational Level-2 products have been available via the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT) for several years. In particular, vertical profiles of water vapor measurements are retrieved from infrared radiances at the global scale. Nevertheless, the robustness of such products has to be checked because only a few validations have been reported. For this purpose, the field experiments that were held during the HyMeX and ChArMEx international programs are a very good opportunity. A H2O-Raman lidar was deployed on the Balearic island of Menorca and operated continuously for ~ 6 and ~ 3 weeks during fall 2012 (Hydrological cycle in the Mediterranean eXperiment - HyMeX) and summer 2013 (Chemistry-Aerosol Mediterranean Experiment - ChArMEx), respectively. It measured simultaneously the water vapor mixing ratio and aerosol optical properties. This article does not aim to describe the IASI operational H2O inversion algorithm, but to compare the vertical profiles derived from IASI onboard (meteorological operational) MetOp-A and the ground-based lidar measurements to assess the reliability of the IASI operational product for the water vapor retrieval in both the lower and middle troposphere. The links between water vapor contents and both the aerosol vertical profiles and the air mass origins are also studied. About 30 simultaneous observations, performed during nighttime in cloud free conditions, have been considered. For altitudes ranging from 2 to 7 km, root mean square errors (correlation) of ~ 0.5 g kg-1 (~ 0.77) and ~ 1.1 g kg-1 (~ 0.72) are derived between the operational IASI product and the available lidar profiles during HyMeX and ChArMEx, respectively. The values of both root mean square error and correlation are meaningful and show that the operational Level-2 product of the IASI-derived vertical water vapor mixing ratio can be considered for meteorological and climatic applications, at least in the framework of field campaigns.

Chazette, P.; Marnas, F.; Totems, J.; Shang, X.

2014-09-01

362

Radiative effects of African dust and smoke observed from Clouds and the Earth's Radiant Energy System (CERES) and Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) data  

NASA Astrophysics Data System (ADS)

Cloud and aerosol effects have a significant impact on the atmospheric radiation budget in the tropical Atlantic because of the spatial and temporal extent of desert dust and smoke from biomass burning in the atmosphere. The influences of African dust and smoke aerosols on cloud radiative properties over the tropical Atlantic Ocean were analyzed for the month of July for 3 years (2006-2008) using colocated data collected by the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) and Clouds and the Earth's Radiant Energy System (CERES) instruments on the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) and Aqua satellites. Aerosol layer height and type can be accurately determined using CALIOP data through directly measured parameters such as optical depth, volume depolarization ratio, attenuated backscatter, and color ratio. On average, clouds below 5 km had a daytime instantaneous shortwave (SW) radiative flux of 270.2 ± 16.9 W/m2 and thin cirrus clouds had a SW radiative flux of 208.0 ± 12.7 W/m2. When dust aerosols interacted with clouds below 5 km, as determined from CALIPSO, the SW radiative flux decreased to 205.4 ± 13.0 W/m2. Similarly, smoke aerosols decreased the SW radiative flux of low clouds to a value of 240.0 ± 16.6 W/m2. These decreases in SW radiative flux were likely attributed to the aerosol layer height and changes in cloud microphysics. CALIOP lidar observations, which more accurately identify aerosol layer height than passive instruments, appear essential for better understanding of cloud-aerosol interactions, a major uncertainty in predicting the climate system.

Yorks, John E.; McGill, Matt; Rodier, Sharon; Vaughan, Mark; Hu, Yongxiang; Hlavka, Dennis

2009-09-01

363

Evaluation of Extinction Profiles and Aerosol Optical Depth from Lidar and DRAGON in the Baltimore-Washington DISCOVER-AQ Experiment (Invited)  

NASA Astrophysics Data System (ADS)

During the 2011 DRAGON experiment and the Deriving Information on Surface Conditions from COlumn and VERtically Resolved Observations Relevant to Air Quality (DISCOVER-AQ) Mission in Baltimore-Washington, comparison of lidar profiles of extinction from the ground and from aircraft could be made with a network of sunphotometers. This comparison revealed excellent agreement between the sunphotometers and lidars in terms of retrieved aerosol optical depth. The lidars were able to determine where in the vertical the scattering aerosols resided. With the exception of one day of the experiment, all aerosols were confined to the PBL and that residual layers and smoke aloft were a minor contributor to the aerosol optical depth. Temporal evolution maps of the region have been made in comparison to model results and show that the DRAGON network captures the spatial as well as temporal variability in the region. In addition, the combination of instruments allow comparison between microphysical retrievals of aerosol optical properties, such as index of refraction and single scatter albedo both in the column and in layers, and size distributions of the aerosol.

Hoff, R. M.; Sawamura, P.; Holben, B. N.; Schafer, J.; Kondragunta, S.; Ferrare, R. A.; Scarino, A. J.; Rogers, R. R.; Obland, M. D.; Hair, J. W.; Hostetler, C. A.; Berkoff, T.; Delgado, R.

2013-12-01

364

Vertical profiles of atmospheric temperature between upper troposphere and mesosphere obtained from Rayleigh/Raman lidar installed at Syowa station in Antarctica  

NASA Astrophysics Data System (ADS)

Atmospheric gravity waves (AGWs) propagating upward from lower atmospheric sources play a dominant role in transporting and depositing energy and momentum from upper troposphere (UT) to lower mesosphere (LM). Particularly, in polar region, these effects of AGWs are well-known to strongly decelerate the polar night jet and drive large scale meridional circulation from the summer pole towards the winter pole. In addition, polar stratospheric clouds (PSCs) described in relation to ozone depletion are effectively induced by orographic AGWs. Therefore, investigation of the activity of AGWs between UT and LM based on continuous observational studies can be regarded as one of important subjects in the middle atmosphere dynamics. The National Institute of Polar Research (NIPR) is leading a six year prioritized project of the Antarctic research observations since 2010. One of the sub-projects is entitled 'the global environmental change revealed through the Antarctic middle and upper atmosphere'. As a part of the sub-project, a Rayleigh/Raman