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1

Raman-shifted eye-safe aerosol lidar.  

PubMed

The design features of, and first observations from, a new elastic backscatter lidar system at a wavelength of 1543 nm are presented. The transmitter utilizes stimulated Raman scattering in high-pressure methane to convert fundamental Nd:YAG radiation by means of the 1st Stokes shift. The wavelength-converting gas cell features multipass operation and internal fans. Unlike previous lidar developments that used Raman scattering in methane, the pump beam is not focused in the present configuration. This feature prevents optical breakdown of the gas inside the cell. Additionally, the gas cell is injection seeded by a diode to improve conversion efficiency and beam quality. The receiver uses a 40.6-cm-diameter telescope and a 200-microm InGaAs avalanche photodiode. The system is capable of operating in a dual-wavelength mode (1064 and 1543 nm simultaneously) for comparison or in a completely eye-safe mode. The system is capable of transmitting an energy of more than 200 mJ/pulse at 10 Hz. Aerosol backscatter data from vertical and horizontal pointing periods are shown. PMID:15250558

Mayor, Shane D; Spuler, Scott M

2004-07-01

2

Validation of temperature measurements from the airborne Raman ozone temperature and aerosol lidar during SOLVE  

Microsoft Academic Search

The Airborne Raman Ozone, Temperature, and Aerosol Lidar (AROTEL) participated in the recent SAGE III Ozone Loss and Validation Experiment (SOLVE) by providing profiles of aerosols, polar stratospheric clouds (PSCs), ozone, and temperature with high vertical and horizontal resolution. Temperatures were derived from just above the aircraft to ~60 km geometric altitude with a reported vertical resolution of ~0.6 km.

John Burris; Thomas McGee; Walter Hoegy; Leslie Lait; Laurence Twigg; Grant Sumnicht; William Heaps; Chris Hostetler; T. Paul Bui; Roland Neuber; I. Stuart McDermid

2002-01-01

3

Validation of temperature measurements from the airborne Raman ozone temperature and aerosol lidar during SOLVE  

Microsoft Academic Search

The Airborne Raman Ozone, Temperature, and Aerosol Lidar (AROTEL) participated in the recent SAGE III Ozone Loss and Validation Experiment (SOLVE) by providing profiles of aerosols, polar stratospheric clouds (PSCs), ozone, and temperature with high vertical and horizontal resolution. Temperatures were derived from just above the aircraft to ?60 km geometric altitude with a reported vertical resolution of ?0.6 km.

John Burris; Thomas McGee; Walter Hoegy; Leslie Lait; Laurence Twigg; Grant Sumnicht; William Heaps; Chris Hostetler; T. Paul Bui; Roland Neuber; I. Stuart McDermid

2002-01-01

4

Retrieving the atmospheric aerosol properties over Beijing region by combining rotational Raman - Mie lidar and CALIPSO  

NASA Astrophysics Data System (ADS)

Typically, we use Klett-Fernald method for retrieving aerosol optical properties. However, the results from these methods critically depend on the lidar ratio, thus affecting the accuracy of the inversion results. In this paper, we adopted a new method to retrieve the vertical distribution profiles of aerosol backscatter coefficient, aerosol extinction coefficient and lidar ratio over Beijing region by combining rotational Raman - Mie lidar and CALIPSO(Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations). The results were compared with the results determined by the conventional method, which shows a good agreement. Compared with the conventional method, the results from this new method are more reliable and less noisy, which provide richer information for researching the atmospheric aerosol properties over Beijing region.

Zhang, Yinchao; Li, Dan; Chen, Binglong; Chen, Siying; Chen, He; Guo, Pan

2013-05-01

5

Retrieval of multi-wavelength aerosol lidar ratio profiles using Raman scattering and Mie backscattering signals  

NASA Astrophysics Data System (ADS)

We advance a novel retrieval technique that combines a Raman and multi-wavelength elastic backscattered signals to retrieve multi-wavelength lidar ratio profiles of aerosol. With profile of backscatter coefficients at 355 nm retrieved from elastic backscatter signal at 355 nm and Raman scattering signal at 387 nm, lidar ratio profiles can be calculated at 532 nm and 1064 nm from the elastic backscatter signals at these wavelengths, taking advantage that the 532 nm/355 nm and 1064 nm/355 nm backscatter ratios are generally approximately equal for two neighboring range bins. This technique has been tested using numerical simulations and applied to lidar measurements at the Hampton University, Hampton, Virginia.

Su, Jia; Liu, Zhaoyan; Wu, Yonghua; McCormick, M. Patrick; Lei, Liqiao

2013-11-01

6

Stratospheric temperature monitoring using a vibrational Raman lidar. Part 1: aerosols and ozone interferences.  

PubMed

Lidar measurements of temperature for the upper troposphere and lower stratosphere are commonly derived by the Raman technique. Lidar signals derived from vibrational Raman processes have been subjected to numerous simulation tests to examine their sensitivity to the presence of aerosols and ozone in the atmosphere. The influence of aerosols characteristics (wavelength dependence of aerosol extinction and particle phase function) and of ozone concentration on Raman temperature profiles is estimated. Simulations indicate large temperature deviations for post-volcanic conditions. For a Raman backscatter at 607 nm, bias is below 1 K for a total optical depth less than 9 x 10(-3) in the case of a stratospheric contamination and less than 6 x 10(-3) for a tropospheric contamination. The effect of aerosols depends on phase function and a few parameters such as altitude, optical depth and the shape of the high-altitude cloud. The wavelength dependence of aerosol extinction has some influence only for severe post-volcanic conditions (Scattering Ratio, SR >2). For a Raman backscatter at 387 nm, bias is larger and can be significant even in background aerosol conditions. Changes in the ozone density profile lead to significant Raman temperature deviations only for some specific conditions. Results suggest that both aerosol and ozone corrections are necessary to obtain an accuracy better than the 1 K requested for most atmospheric applications. PMID:15798803

Faduilhe, Denis; Keckhut, Philippe; Bencherif, Hassan; Robert, Laurent; Baldy, Serge

2005-02-23

7

Atmospheric aerosol characterization combining multi-wavelength Raman lidar and MAX-DOAS measurements in Gwanjgu  

NASA Astrophysics Data System (ADS)

Integrated approach has been adopted at the ADvanced Environmental Research Center (ADEMRC), Gwangju Institute of Science and Technology (GIST), Korea for effective monitoring of atmospheric aerosol. Various active and passive optical remote sensing techniques such as multi-wavelength (3?+2?+1?) Raman LIDAR, sun-photometry, MAX-DOAS, and satellite retrieval have been utilized. This integrated monitoring system approach combined with in-situ surface measurement is to allow better characterization of physical and optical properties of atmospheric aerosol. Information on the vertical distribution and microphysical properties of atmospheric aerosol is important for understanding its transport characteristics as well as radiative effect. The GIST multi-wavelength (3? + 2?+1?) Raman lidar system can measure vertical profiles of optical properties of atmospheric aerosols such as extinction coefficients at 355 and 532nm, particle backscatter coefficients at 355, 532 and 1064 nm, and depolarization ratio at 532nm. The incomplete overlap between the telescope field-of-view and beam divergence of the transmitting laser significantly affects lidar measurement, resulting in higher uncertainty near the surface where atmospheric aerosols of interest are concentrated. Differential Optical Absorption Spectroscopy (DOAS) technique is applied as a complementary tool for the detection of atmospheric aerosols near the surface. The passive Multi-Axis DOAS (MAX-DOAS) technique uses scattered sunlight as a light source from several viewing directions. Recently developed aerosol retrieval algorithm based on O4 slant column densities (SCDs) measured at UV and visible wavelengths has been utilized to derive aerosol information (e.g., aerosol optical depth (AOD) and aerosol extinction coefficients (AECs)) in the lower troposphere. The aerosol extinction coefficient at 356 nm was retrieved for the 0-1 and 1-2 km layers based on the MAX-DOAS measurements using the retrieval algorithm. Ground-based measurements of tropospheric aerosol using multi-wavelength Raman lidar system and a mobile MAX-DOAS system had been carried out at the Gwangju Institute of Science and Technology (GIST). To evaluate the performance of the integrated measurement system (Lidar + MAX-DOAS), an aerosol retrieval method called STAR (satellite aerosol retrieval) has been applied to compare the satellite AOD products with those based on the Raman lidar and MAX-DOAS measurements. It allows complete monitoring of atmospheric aerosols' vertical profiles for better estimation of their radiative effects on atmospheric environment and climate change.

Chong, Jihyo; Shin, Dong Ho; Kim, Kwang Chul; Lee, Kwon-Ho; Shin, Sungkyun; Noh, Young M.; Müller, Detlef; Kim, Young J.

2011-10-01

8

Design and development of multiwavelength Mie-Polarization-Raman aerosol lidar system  

NASA Astrophysics Data System (ADS)

Atmospheric aerosols play a major role in many atmospheric processes concerning the earth's radiation budget, air quality, clouds and percipitation, and atmospheric chemistry. A multiwavelength Mie-Polarization-Raman lidar system is developing at Shandong Academy of Sciences Institute of Oceanorgraphic Instrumentation (SDIOI), which is used for the profiling of optical and physical aerosol properties. This system is specifically designed for characterizing marine aerosol which consists of a complex mix of different aerosol types. The aerosol lidar consists of a tripled Nd:YAG laser with three wavelengths, 30 cm telescope, six receiver channels and data acquistion subsystem. It provides particle backscatter coefficients at 355, 532 and 1064 nm (3?), extinction coefficients at 355 and 532 nm (2?), and depolarization ratio (?). There are two Raman channels to collect the Raman signals backscattered by nitrogen molecules at 607 nm and by water vapor moecules at 407 nm. In this paper, we mainly describe the details of the optical setup, structure and performance of the lidar system. At last, the simulated signals based on the specifications are presented to demonstrate the capabilities of the lidar system.

Wang, Zhang-jun; Du, Li-bin; Li, Xian-xin; Chen, Chao; Qu, Jun-le; Liu, Jie; Lv, Bin

2013-09-01

9

Doppler wind lidar sensitivity and aerosol backscatter ratio measurement by combined Raman-Mie-Rayleigh scattering  

NASA Astrophysics Data System (ADS)

Direct Detect Doppler wind lidar retrieves the three dimensional wind by discriminating the frequency shift of the atmosphere elastic backscatter signal. The wind measurement sensitivity of edge detect technology based on iodine absorption lines highly depends on the aerosol backscatter ratio indicating the mixing ratio of aerosol to atmosphere molecule in the measurement volume. This work adopt an extra nitrogen Raman channel in addition to elastic Mie and Rayleigh scattering so as to retrieve the aerosol backscatter coefficient on site and in real time. The Doppler lidar transmitter is a single longitudinal mode laser at 532 nm, and the lidar receiver analyzes elastic-scatter spectrum of central wavelength at 532 nm, nitrogen Raman spectrum of central wavelength at 607 nm. The lidar prototype is validated by experiment. Results show that this method is capable of measuring aerosol backscatter ratio profile of low-altitude troposphere at the same time as wind measurement, which can define the wind measurement sensitivity and improve the accuracy of wind speed retrieval.

Wu, Songhua; Chen, Yang; Song, Zhilong; Qin, Shengguang; Jin, Lei; Zhang, Wei

2011-06-01

10

The applicability of a scanning Raman lidar for measurements of aerosols and water vapor  

NASA Astrophysics Data System (ADS)

Assessing atmospheric water vapor measurements to the level of accuracy required for improving atmospheric radiation parameterizations has been difficult to achieve. This thesis describes how a new sensor, the NASA/GSFC Scanning Raman Lidar (SRL), is used to improve assessments of water vapor measurements. Water vapor profiles measured at night by this lidar during two field experiments are compared with those measured by radiosondes, dew point hygrometers, a microwave radiometer, sun photometers, and the LASE lidar. During the first experiment, the SRL data show differences in water vapor mixing ratio and precipitable water vapor measurements as high as 10-15%; during the second, the SRL data reveal: (1) 10-15% differences in the Vaisala and VIZ radiosonde water vapor mixing ratio profiles below two kilometers, and (2) agreement within 5% between the SRL, dew point hygrometers, and LASE. These comparisons show that, by measuring water vapor to within about 5%, the SRL can be used to evaluate point, profile, and integrated water vapor measurements. Since this lidar detects Raman scattering from nitrogen and oxygen as well as the elastic scattering from molecules and aerosols, it measures both aerosol backscattering and extinction simultaneously with water vapor in the same scattering volume. Therefore, this instrument is well suited to study the interaction between water vapor and aerosols. Measurements of aerosol scattering from a tower-mounted nephelometer are found to be 40% lower than lidar measurements of aerosol extinction over a wide range of relative humidities even after accounting for the difference in wavelengths. The lidar profiles of aerosol backscattering and extinction compare well with those derived from aerosol size distribution measurements made by a PCASP (Passive Cavity Aerosol Spectrometer Probe) optical particle counter. Using both measurements, the change in particle size with relative humidity, the aerosol real refractive index n, and the single scattering albedo ?o are derived and are shown to vary with time and altitude. Values of n ranged between 1.4-1.5 (dry) and 1.37-1.47 (wet); ?o varied between 0.7-1.0. The SRL data show the ratio of aerosol extinction at 80% relative humidity to that at 60% relative humidity varies between 1.7 to 2.1.

Ferrare, Richard Anthony

1997-12-01

11

Atmospheric aerosol characterization combining multi-wavelength Raman lidar and MAX-DOAS measurements in Gwanjgu  

Microsoft Academic Search

Integrated approach has been adopted at the ADvanced Environmental Research Center (ADEMRC), Gwangju Institute of Science and Technology (GIST), Korea for effective monitoring of atmospheric aerosol. Various active and passive optical remote sensing techniques such as multi-wavelength (3beta+2alpha+1delta) Raman LIDAR, sun-photometry, MAX-DOAS, and satellite retrieval have been utilized. This integrated monitoring system approach combined with in-situ surface measurement is to

Jihyo Chong; Dong Ho Shin; Kwang Chul Kim; Kwon-Ho Lee; Sungkyun Shin; Young M. Noh; Detlef Müller; Young J. Kim

2011-01-01

12

High resolution humidity, temperature and aerosol profiling with MeteoSwiss Raman lidar  

NASA Astrophysics Data System (ADS)

Meteorological services rely, in part, on numerical weather prediction (NWP). Twice a day radiosonde observations of water vapor provide the required data for assimilation but this time resolution is insufficient to resolve certain meteorological phenomena. High time resolution temperature profiles from microwave radiometers are available as well but have rather low vertical resolution. The Raman LIDARs are able to provide temperature and humidity profiles with high time and range resolution, suitable for NWP model assimilation and validation. They are as well indispensible tools for continuous aerosol profiling for high resolution atmospheric boundary layer studies. To improve the database available for direct meteorological applications 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 design and build an automated Raman lidar for day and night vertical profiling of tropospheric water vapor with the possibility to further upgrade it with an aerosol and temperature channels. The project was initiated in 2004 and RALMO (Raman Lidar for meteorological observations) was inaugurated in August 2008 at MeteoSwiss aerological station at Payerne. RALMO is currently operational and continuously profiles water vapor mixing ratio, aerosol backscatter ratio and aerosol extinction. The instrument is a fully automated, self-contained, eye-safe Raman lidar operated at 355 nm. Narrow field-of-view multi-telescope receiver and narrow band detection allow day and night-time vertical profiling of the atmospheric humidity. The rotational-vibrational Raman lidar responses from water vapor and nitrogen are spectrally separated by a high-throughput fiber coupled diffraction grating polychromator. The elastic backscatter and pure-rotational Raman lidar responses (PRR) from oxygen and nitrogen are spectrally isolated by a double grating polychromator and are used to derive vertical profiles of aerosol backscatter ratio and aerosol extinction at 355 nm. Set of Stokes and anti-Stokes PRR lines are separated by the polychromator to derive temperature profiles. The humidity profiles have vertical resolution from 15 m (within the boundary layer) to 100-450 m (within the free troposphere), time resolution of 30 min and 5 km vertical range at daytime and 10 km at night-time. The aerosol backscatter ratio and extinction profiles have similar resolution with vertical range of approximately 10 km. The temperature profiles are derived from PRR lidar signals, simultaneously recorded in analog and photon counting mode, allowing vertical range of approximately 10 km. Vaisala RS-92 and Snow-White chilled mirror hygrometer radiosondes were used for calibration of the water vapor and temperature channels. Continuous temperature profiles were obtained and were coupled with the available water vapor mixing ratio profiles to obtain relative humidity time series. Lidar derived aerosol backscatter ratio profiles will be used for estimation of the boundary layer height and validation of NWP model results. Optical thickness time series are currently compared to independent measurements from a collocated sun photometer to assess the performance of the aerosol channel.

Dinoev, Todor; Arshinov, Yuri; Bobrovnikov, Sergei; Serikov, Ilya; Calpini, Bertrand; van den Bergh, Hubert; Parlange, Marc B.; Simeonov, Valentin

2010-05-01

13

Aerosol Optical Properties Characterization By Means Of The CNR-IMAA Multi-Wavelength Raman Lidar  

NASA Astrophysics Data System (ADS)

A Raman/elastic lidar for tropospheric aerosol study is operational at CNR-IMAA (40°36'N, 15°44'E, 760 m above sea level) since May 2000 in the framework of EARLINET. Since August 2005, this system provides aerosol backscatter coefficient profiles at 1064 nm, and independent measurements of aerosol extinction and backscatter coefficient profiles at 355 and 532 nm. In this way, lidar ratio (i.e. extinction to backscatter ratio) profiles at 355 and 532 nm are also obtained. In addition, depolarization ratio measurements at 532 nm are obtained by means of detection of components of backscattered light polarized perpendicular and parallel to the direction of the linearly polarized transmitted laser beam. Depolarization ratio measurements provide information about shape and orientation of aerosolic particles, while lidar ratio measurements and wavelength dependences of both backscatter and extinction are important for aerosol characterization in terms of aerosol type and size. In addition, high quality multi-wavelength measurements (3 backscatter + 2 extinction) can allow the determination of microphysical aerosol properties (refractive index, single-scattering albedo and effective particles radii). Systematic measurements are performed three times per week according to the EARLINET schedule since May 2000, and further measurements are performed in order to investigate particular events, like dust intrusions, volcanic eruptions and forest fires. This extended dataset allows the optical characterization of aerosol located close to the surface, namely in the Planetary Boundary Layer, as well as in the free troposphere. In the free troposphere, an high occurrence of Saharan dust intrusions at CNR-IMAA (about 1 day of Saharan dust intrusion every 10 days) has been identified by means of back-trajectory analysis and in accordance with satellite images, because of the short distance from the Sahara region. In addition, CNR-IMAA is pretty close to Etna, the largest European volcano, providing the opportunity to characterize volcanic aerosol properties too. Moreover, forest fires contribution to the aerosol load is not negligible during summer, when large forest fires typically occur in Southern Europe. Therefore the CNR-IMAA multi-wavelength Raman lidar system allows the characterization of aerosol optical properties for a large variety of events and atmospheric situations and to study the aerosol properties modification processes occurred during their transportation over continental scale. ACKNOWLEDGMENTS The financial support for EARLINET by the European Commission under grant RICA-025991 is gratefully acknowledged.

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

2007-12-01

14

Evaluation of daytime measurements of aerosols and water vapor made by an operational Raman lidar over the Southern Great Plains  

Microsoft Academic Search

Raman lidar water vapor and aerosol extinction profiles acquired during the daytime over the Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) site in northern Oklahoma (36.606 N, 97.50 W, 315 m) are evaluated using profiles measured by in situ and remote sensing instruments deployed during the May 2003 Aerosol Intensive Operations Period (IOP). The automated

Richard Ferrare; David Turner; Marian Clayton; Beat Schmid; Jens Redemann; David Covert; Robert Elleman; John Ogren; Elisabeth Andrews; John E. M. Goldsmith; Haflidi Jonsson

2006-01-01

15

Volcanic aerosol layers observed with multi-wavelength Raman lidar over Europe since summer 2008  

NASA Astrophysics Data System (ADS)

Regular multiwavelength Raman lidar observations of the vertical aerosol distribution have been performed at Leipzig (51.4°N, 12.4°E), Germany, since 1996 in the framework of the European Aerosol Research Lidar Network (EARLINET). Our measurements in the past 12 years do not show any major event of volcanic aerosol pollution in the upper troposphere-lower stratosphere (UTLS) region. The situation changed since summer of 2008 due to a series of strong eruptions of volcanoes on the Aleutian Islands, Kamchatka, Alaska, and on the Kuril Islands. We observed aerosol layers in the upper troposphere above 5 km height and lower stratosphere below 25 km height. FLEXPART transport simulations show that volcanic aerosol is advected from Alaska to central Europe within about 7 days. The optical depths of the volcanic aerosol layers are mostly between 0.004 and 0.025 at 532 nm. The wavelength dependence of the backscatter and extinction coefficients indicate Ångström exponents from 1.0-2.0. Lidar ratios are found in the range from 30-80 sr (355 nm) and 30-50 sr (532 nm). The estimation of the effective radius, surface-area, and mass concentrations of a volcanic aerosol layer, observed well within the stratosphere end of August 2009, reveals values of 0.1-0.2 ?m, 5-10 ?m2 cm-3, and 0.3-0.5 ?g m-3, respectively. The surface-area and mass concentrations are thus about a factor of 10-20 lower than the respective values observed after the Mt. Pinatubo eruption in the years 1992 and 1993.

Mattis, Ina; Seifert, Patric; Müller, Detlef; Tesche, Matthias; Hiebsch, Anja; Kanitz, Thomas; Schmidt, Jörg; Finger, Fanny

2010-05-01

16

Continuous and automatic measurement of atmospheric structures and aerosols optical properties with R-Man510 nitrogen Raman lidar  

NASA Astrophysics Data System (ADS)

A new compact and light nitrogen Raman lidar (R-Man510) has recently been developed by Leosphere company. This UV-lidar system is based on a low energy diode pumped Nd:YAG laser at 355 nm and has been developed to be operated unmanly for the meteorological and airport needs. Measurements are typically performed with a vertical resolution between 15 and 60 m and a temporal resolution between 30 seconds (for elastic channel) and 10 minutes (for Raman channel). The elastic channel of the lidar is used to automatically detect up to 9 atmospheric structures (Plantery Boundary Layer height, aerosol and cloud layers) in quasi real-time. Aerosols are classified in 6 types (pollution aerosols, desert dusts, volcanic ashes, marine aerosols, biomass burning and no aerosols) considering informations on depolarization ratio determined with the two cross-polarized elastic channels and on aerosols optical properties (extinction-to-backscatter ratio, aerosol backscatter and extinction coefficients) determined thanks to the nitrogen Raman channel at 387 nm. Aerosols optical properties can then been used for the assessment of mass concentrations which is crucial in case of hypothetical volcanic eruption. We will present the first results obtained with this new commercial lidar system. Daytime and nighttime performances of the system will be analyzed and compared with simulations from an instrumental model.

Royer, P.; Renaudier, M.; Sauvage, L.; Boquet, M.; Thobois, L.; Bizard, A.

2012-04-01

17

Recent improvements to the Raman-shifted eye-safe aerosol lidar (REAL)  

NASA Astrophysics Data System (ADS)

Improvements to the original NCAR/NSF Raman-shifted Eye-safe Aerosol Lidar (REAL) made between 2008 and 2013 are described. They are aimed mainly at optimizing and stabilizing the performance of the system for long-term, unattended, network-controlled, remote monitoring of the horizontal vector wind field and boundary layer height, and observing atmospheric boundary layer phenomena such as fine-scale waves and density current fronts. In addition, we have improved the polarization purity of the transmitted laser radiation and studied in the laboratory the effect of the beam-steering unit mirrors on the transmitted polarization as part of a longer-term effort to make absolute polarization measurements of aerosols and clouds.

Mayor, Shane D.; Petrova-Mayor, Anna; Morley, Bruce; Spuler, Scott

2013-09-01

18

Raman Lidar (RL) Handbook  

SciTech Connect

The Raman lidar at the ARM Climate Research Facility (ACRF) Southern Great Plains (SGP) Central Facility (SGPRL) is an active, ground-based laser remote sensing instrument that measures height and time resolved profiles of water vapor mixing ratio and several cloud- and aerosol-related quantities. The system is a non-commercial custom-built instrument developed by Sandia National Laboratories specifically for the ARM Program. It is fully computer automated, and will run unattended for many days following a brief (~5-minute) startup period. The self-contained system (requiring only external electrical power) is housed in a climate-controlled 8’x8’x20’ standard shipping container.

Newsom, RK

2009-03-01

19

N2-Raman lidar for dust aerosol survey over the southern Spain within the frame 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. We will present the contribution of the French ground-based lidar to the FENNEC program. A N2-Raman lidar equipped with co-polar and cross-polar channels has been implemented in the South-Eastern part of Spain, close to Marbella, in the center of San Pedro de Alcantara on a building flat roof. The lidar worked in synergy with a sunphotometer, which data are now a contribution to the AERONET network. The lidar measurements have been performed continuously by about 2.5 months between the 6 June and 26 August 2011. It is a valuable asset for monitoring dust aerosols within the atmospheric column and to separate their contribution from the local aerosol production. Indeed, several dust events with aerosol optical thickness larger than 0.5 at 355 nm were sampled, influencing the planetary boundary layer and the free troposphere until ~7 km height. Such events have been shown to be more originating from Morocco and Algeria, although more distant contribution can occur from Mauritania sources.

Chazette, P.; Royer, P.; Marnas, F.; Flamant, C.; Doira, P.; Grenier, C.; Sanak, J.

2012-04-01

20

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

21

Esrange lidar's new pure rotational-Raman channel for measurement of temperature and aerosol extinction in the troposphere and lower stratosphere  

NASA Astrophysics Data System (ADS)

The Department of Meteorology at Stockholm University operates the Esrange Rayleigh/Raman lidar at Esrange (68° N, 21° E) near the Swedish city of Kiruna. This paper describes the design and first measurements of the new pure rotational-Raman channel of the Esrange lidar. The Esrange lidar uses a pulsed Nd:YAG solid-state laser operating at 532 nm as light source with a repetition rate of 20 Hz and a pulse energy of 350 mJ. The minimum vertical resolution 150 m and the integration time for one profile is 5000 shots. The newly implemented channel allows for measurements of atmospheric temperature at altitudes below 35 km and is currently optimized for temperature measurements between 180 and 200 K. This corresponds to conditions in the lower Arctic stratosphere during winter. In addition to the temperature measurements the aerosol extinction coefficient and the aerosol backscatter coefficient at 532 nm can be measured independently. Our filter-based design minimizes the systematic error in the obtained temperature profile to less than 0.51 K. By combining rotational-Raman measurements (5-35 km height) and the integration technique (30-80 km height), the Esrange lidar is now capable of measuring atmospheric temperature profiles from the lower troposphere up to the mesosphere. With the improved setup, the system can be used to validate current lidar-based polar stratospheric cloud classification schemes. The new capability of the instrument measuring temperature and aerosol extinction furthermore enables studies of the thermal structure and variability of the upper troposphere/lower stratosphere. Although several lidars are operated at polar latitudes, there are few instruments that are capable to measure temperature profiles in the troposphere, stratosphere, and mesosphere, as well as aerosols extinction in the troposphere and lower stratosphere with daylight capability.

Achtert, P.; Khaplanov, M.; Khosrawi, F.; Gumbel, J.

2012-09-01

22

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

23

Monitoring O3 with solar-blind Raman lidars.  

PubMed

The benefits of retrieving ozone concentration profiles by a use of a single Raman signal rather than the Raman differential absorption lidar (DIAL) technique are investigated by numerical simulations applied either to KrF- (248 nm) or to quadrupled Nd:YAG- (266 nm) based Raman lidars, which are used for both daytime and nighttime monitoring of the tropospheric water-vapor mixing ratio. It is demonstrated that ozone concentration profiles of adequate accuracy and spatial and temporal resolution can be retrieved under low aerosol loading by a single Raman lidar because of the large value of the ozone absorption cross section both at 248 nm and at 266 nm. Then experimental measurements of Raman signals provided by the KrF-based lidar operating at the University of Lecce (40 degrees 20'N, 18 degrees 6'E) are used to retrieve ozone concentration profiles by use of the Raman DIAL technique and the nitrogen Raman signal. PMID:18357117

de Tomasi, F; Perrone, M R; Protopapa, M L

2001-03-20

24

Technical Note: One year of Raman-lidar measurements in Gual Pahari EUCAARI site close to New Delhi in India - Seasonal characteristics of the aerosol vertical structure  

NASA Astrophysics Data System (ADS)

One year of multi-wavelength (3 backscatter + 2 extinction + 1 depolarization) Raman lidar measurements at Gual Pahari, close to New Delhi, were analysed. The data was split into four seasons: spring (March-May), summer (June-August), autumn (September-November) and winter (December-February). The vertical profiles of backscatter, extinction, and lidar ratio and their variability during each season are presented. The measurements revealed that, on average, the aerosol layer was at its highest in spring (5.5 km). In summer, the vertically averaged (between 1-3 km) backscatter and extinction coefficients had the highest averages (3.3 Mm-1 sr-1 and 142 Mm-1 at 532 nm, respectively). Aerosol concentrations were slightly higher in summer compared to other seasons, and particles were larger in size. The autumn showed the highest lidar ratio and high extinction-related Ångström exponents (AEext), indicating the presence of smaller probably absorbing particles. The winter had the lowest backscatter and extinction coefficients, but AEext was the highest, suggesting still a large amount of small particles.

Komppula, M.; Mielonen, T.; Arola, A.; Korhonen, K.; Lihavainen, H.; Hyvärinen, A.-P.; Baars, H.; Engelmann, R.; Althausen, D.; Ansmann, A.; Müller, D.; Panwar, T. S.; Hooda, R. K.; Sharma, V. P.; Kerminen, V.-M.; Lehtinen, K. E. J.; Viisanen, Y.

2012-05-01

25

Optical-microphysical properties of Saharan dust aerosols and composition relationship using a multi-wavelength Raman lidar, in situ sensors and modelling: a case study analysis  

NASA Astrophysics Data System (ADS)

A strong Saharan dust event that occurred over the city of Athens, Greece (37.9° N, 23.6° E) between 27 March and 3 April 2009 was followed by a synergy of three instruments: a 6-wavelength Raman lidar, a CIMEL sun-sky radiometer and the MODIS sensor. The BSC-DREAM model was used to forecast the dust event and to simulate the vertical profiles of the aerosol concentration. Due to mixture of dust particles with low clouds during most of the reported period, the dust event could be followed by the lidar only during the cloud-free day of 2 April 2009. The lidar data obtained were used to retrieve the vertical profile of the optical (extinction and backscatter coefficients) properties of aerosols in the troposphere. The aerosol optical depth (AOD) values derived from the CIMEL ranged from 0.33-0.91 (355 nm) to 0.18-0.60 (532 nm), while the lidar ratio (LR) values retrieved from the Raman lidar ranged within 75-100 sr (355 nm) and 45-75 sr (532 nm). Inside a selected dust layer region, between 1.8 and 3.5 km height, mean LR values were 83 ± 7 and 54 ± 7 sr, at 355 and 532 nm, respectively, while the Ångström-backscatter-related (ABR355/532) and Ångström-extinction-related (AER355/532) were found larger than 1 (1.17 ± 0.08 and 1.11 ± 0.02, respectively), indicating mixing of dust with other particles. Additionally, a retrieval technique representing dust as a mixture of spheres and spheroids was used to derive the mean aerosol microphysical properties (mean and effective radius, number, surface and volume density, and mean refractive index) inside the selected atmospheric layers. Thus, the mean value of the retrieved refractive index was found to be 1.49( ± 0.10) + 0.007( ± 0.007)i, and that of the effective radiuses was 0.30 ± 0.18 ?m. The final data set of the aerosol optical and microphysical properties along with the water vapor profiles obtained by Raman lidar were incorporated into the ISORROPIA II model to provide a possible aerosol composition consistent with the retrieved refractive index values. Thus, the inferred chemical properties showed 12-40% of dust content, sulfate composition of 16-60%, and organic carbon content of 15-64%, indicating a possible mixing of dust with haze and smoke. PM10 concentrations levels, PM10 composition results and SEM-EDX (Scanning Electron Microscope-Energy Dispersive X-ray) analysis results on sizes and mineralogy of particles from samples during the Saharan dust transport event were used to evaluate the retrieval.

Papayannis, A.; Mamouri, R. E.; Amiridis, V.; Remoundaki, E.; Tsaknakis, G.; Kokkalis, P.; Veselovskii, I.; Kolgotin, A.; Nenes, A.; Fountoukis, C.

2012-05-01

26

Estimation of the microphysical aerosol properties over Thessaloniki, Greece, during the SCOUT-O3 campaign with the synergy of Raman lidar and Sun photometer data  

NASA Astrophysics Data System (ADS)

An experimental campaign was held at Thessaloniki, Greece (40.6°N, 22.9°E), in July 2006, in the framework of the integrated project Stratosphere-Climate Links with Emphasis on the Upper Troposphere and Lower Stratosphere (SCOUT-O3). One of the main objectives of the campaign was to determine the local aerosol properties and their impact on the UV irradiance at the Earth's surface. In this article, we present vertically resolved microphysical aerosol properties retrieved from the inversion of optical data that were obtained from a combined one-wavelength Raman/two-wavelength backscatter lidar system and a CIMEL Sun photometer. A number of assumptions were undertaken to overcome the limitations of the existing optical input data needed for the retrieval of microphysical properties. We found acceptable agreement with Aerosol Robotic Network retrievals for the fine-mode particle effective radius, which ranged between 0.11 and 0.19 for the campaign period. It is shown that under complex layering of the aerosols, general assumptions may result in unrealistic retrievals, especially in the presence of aged smoke aerosols. Furthermore, with this instrument setup, the inversion algorithm can also be applied successfully for the complex refractive index in cases of vertically homogeneous layers of continental polluted aerosols. For these inversion cases, the vertically resolved retrievals for the single-scattering albedo resulted in values around 0.9 at 532 nm, which were in very good agreement with estimates from airborne in situ observations obtained in the vicinity of the lidar site.

Balis, D.; Giannakaki, E.; Müller, D.; Amiridis, V.; Kelektsoglou, K.; Rapsomanikis, S.; Bais, A.

2010-04-01

27

Comparison of AOD and Lidar ratios retrieved from a synergy of multiwavelength Raman Lidar, backscatter CAML lidar and AERONET sunphotometry  

NASA Astrophysics Data System (ADS)

Backscatter lidar profiles from the Raman multiwavelength Iidar, backscatter profiles from CAML lidar and aerosol optical depths (AODs) from the AERONET network at Ispra (Varese) Italy, were acquired during 2012-2013. We will present several cases events showing the importance in retrieving different parameters such as AODs, extinction coefficients, colour ratios and depolarization ratios when using synergy of several instruments especially ground based lidars and sunphotometers. Multiwavelength Raman lidar and sunphotometry increase the accuracy of lidar ratio (LR) values, we will show some LR daily variations depending on the several and different events acquired. Preliminary results of comparison between LR and AODs show a degree of physical coherency using our two lidars and the sunphotometer. We will be using CALIPSO satellite profiles when it is possible to compare AODs and LR with our ground based measurements. Brief conclusion will be presented during this communication, about the daily variations of the LR, for different atmospheric events.

Daou, David; Putaud, Jean Philippe

2013-04-01

28

Investigation of cloud properties using a Raman lidar  

NASA Astrophysics Data System (ADS)

Raman lidar is well known to be a useful tool for charting the evolution of water vapor and aerosols in the atmosphere. The goal of this dissertation is to use the Raman lidar technique to study cloud properties that are important in understanding atmospheric radiation and dynamics. The lidar system used here is the NASA/GSFC Scanning Raman Lidar. A detailed description of this state of the art Raman lidar is given. The system configuration and several important optical design considerations are described fully. Following this, a detailed derivation of the basic equations pertaining to the Raman lidar measurement of aerosol backscattering ratio, aerosol backscatter coefficient, aerosol extinction, aerosol optical depth and water vapor mixing ratio are given. In the process, a new formulation of the lidar equations is presented that accounts for the temperature sensitivity of the backscattered spectra. A detailed analysis of the method of computing aerosol extinction is presented. Analysis of Raman lidar data using these equations is shown. Then, a new technique is developed that allows droplet radius and number density to be retrieved from liquid clouds. The technique is demonstrated using Raman lidar data. In support of this new atmospheric technique, laboratory measurements of the Raman scattering of liquid water were performed demonstrating that aspects of the backscattered spectrum of liquid water agree with theory. The influence of multiple scattering on optical depth is studied resulting in a technique that allows the bulk extinction to backscatter ratio of the cirrus clouds to be determined. It also allows information about the particle size to be determined. A 6-night sequence of cirrus cloud optical depth measurements acquired on Andros Island, Bahamas is presented. They were acquired during the nearby passage of hurricane Bonnie. The radiative significance of cirrus clouds is studied for one of these nights. The study reveals that cirrus clouds dominate the radiance seen by satellite and that cirrus clouds with optical depths as low as 0.005 can influence satellite radiances. Using the International Satellite Cloud Climatology Project cirrus cloud detection thresholds implies up to a 40% high bias in retrieved total precipitable water due to undetected cirrus clouds. This result has potentially important consequences for the global database of precipitable water determined using IR satellite measurements.

Whiteman, David Neil

29

Lidar Observations of Volcanic Aerosol Layers Over Halifax, Canada  

NASA Astrophysics Data System (ADS)

Lidar measurements of vertical aerosol distributions from late summer 2008 indicate the presence of unusual aerosol layers in the upper troposphere and lower stratosphere over Halifax, Nova Scotia in Eastern Canada (44.64°N, 63.59°W). Trajectory analyses indicate that the sources of the aerosol layers were the explosive 7-8 August eruptions of Kasatochi volcano in the Aleutian Volcanic Arc (52.17°N, 175.51°W). The aerosol plumes were detected on multiple days throughout August and September by the Dalhousie Raman Lidar. A new high-altitude receiver addition to the lidar system is being used to enhance investigation of the optical characteristics as well as the vertical and temporal structures of the observed volcanic aerosol layers.

Bitar, L.; Duck, T. J.; Doyle, J.; Perro, C.

2008-12-01

30

Raman lidar observations of particle hygroscopicity during COPS  

NASA Astrophysics Data System (ADS)

The characterization of particle hygroscopicity has primary importance for climate monitoring and prediction. Model studies have demonstrated that relative humidity (RH) has a critical influence on aerosol climate forcing. The relationship between aerosol backscattering and relative humidity has been investigated in numerous studies (among others, Pahlow et al., 2006; Wulfmeyer and Feingold, 2000; Veselovskii et al., 2009). Hygroscopic properties of aerosols influence particle size distribution and refractive index and hence their radiative effects. Aerosol particles tend to grow at large relative humidity values as a result of their hygroscopicity. Raman lidars with aerosol, water vapour and temperature measurement capability are potentially attractive tools for studying aerosol hygroscopicity as in fact they can provide continuous altitude-resolved measurements of particle optical, size and microphysical properties, as well as relative humidity, without perturbing the aerosols or their environment. Specifically, the University of Basilicata Raman lidar system (BASIL) considered for the present study, has the capability to perform all-lidar measurements of relative humidity based on the application of both the rotational and the vibrational Raman lidar techniques in the UV. BASIL was operational in Achern (Black Forest, Lat: 48.64 ° N, Long: 8.06 ° E, Elev.: 140 m) between 25 May and 30 August 2007 in the framework of the Convective and Orographically-induced Precipitation Study (COPS). During COPS, BASIL collected more than 500 hours of measurements, distributed over 58 measurement days and 34 intensive observation periods (IOPs). The present analysis is focused on selected case studies characterized by the presence of different aerosol types with different hygroscopic behaviour. The observed behaviour, dependent upon aerosol composition, may range from hygrophobic to strongly hygroscopic. Results from the different case studies will be illustrated and discussed at the Conference.

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

2012-04-01

31

Particle backscatter, extinction, and lidar ratio profiling with Raman lidar in south and north China  

SciTech Connect

Aerosol Raman lidar observations of profiles of the particle extinction and backscatter coefficients and the respective extinction-to-backscatter ratio (lidar ratio) were performed under highly polluted conditions in the Pearl River Delta (PRD) in southern China in October 2004 and at Beijing during a clear period with moderately polluted to background aerosol conditions in January 2005. The anthropogenic haze in the PRD is characterized by volume light-extinction coefficients of particles ranging from approximately 200 to800 Mm-1 and lidar ratios mostly between 40 and 55 sr (average of47{+-}6 sr). Almost clean air masses were observed throughout the measurements of the Beijing campaign. These air masses originated from arid desert-steppe-like regions (greater Gobi area).Extinction values usually varied between 100 and300 Mm-1, and the lidar ratios were considerably lower (compared with PRD values) with values mostly from 30 to 45 sr (average of38{+-}7 sr). Gobi dust partly influenced the observations. Unexpectedly low lidar ratios of approximately 25 sr were found for a case of background aerosol with a low optical depth of 0.05. The low lidar ratios are consistent with Mie-scattering calculations applied to ground-based observations of particle size distributions.

Tesche, Matthias; Ansmann, Albert; Mueller, Detlef; Althausen, Dietrich; Engelmann, Ronny; Hu Min; Zhang Yuanghang

2007-09-01

32

Independent measurements of Raman LIDAR water vapor calibration factor  

Microsoft Academic Search

One of the goals of LIDAR scientists is to obtain long term monitoring of water vapor using Raman LIDAR [1]. Previous LIDAR research suggests that the measurement of water vapor can be improved by better analysis of the LIDAR system’s calibration factor. Currently LIDAR scientists generally use radiosonde data to calibrate LIDAR data. We are using a standard lamp calibration

M. N. Calhoun; D. D. Venable; D. N. Whiteman

2011-01-01

33

Validation of CALIPSO space-borne-derived aerosol vertical structures using a ground-based lidar in Athens, Greece  

Microsoft Academic Search

We present initial aerosol validation results of the space-borne lidar CALIOP retrievals -onboard the CALIPSO satellite-, using coincident observations performed with a ground-based lidar in Athens, Greece (37.9° N, 23.6° E). A multi-wavelength ground-based backscatter\\/Raman lidar system is operating since 2000 at the National Technical University of Athens (NTUA) in the framework of the European Aerosol Research LIdar NETwork (EARLINET),

R. E. Mamouri; V. Amiridis; A. Papayannis; E. Giannakaki; G. Tsaknakis; D. S. Balis

2009-01-01

34

AMALi - the Airborne Mobile Aerosol Lidar for Arctic research  

NASA Astrophysics Data System (ADS)

The Airborne Mobile Aerosol Lidar (AMALi) is an instrument developed at the Alfred Wegener Institute for Polar and Marine Research for reliable operation under the challenging weather conditions at the Earth's polar regions. Since 2003 the AMALi has been successfully deployed for measurements in ground-based installation and zenith- or nadir-pointing airborne configurations during several scientific campaigns in the Arctic. The lidar provides backscatter profiles at two wavelengths (355/532 nm or 1064/532 nm) together with the linear depolarization at 532 nm, from which aerosol and cloud properties can be derived. This paper presents the characteristics and capabilities of the AMALi system and gives examples of its usage for airborne and ground-based operations in the Arctic. As this backscatter lidar normally does not operate in aerosol-free layers special evaluation schemes are discussed, the nadir-pointing iterative inversion for the case of an unknown boundary condition and the two-stream approach for the extinction profile calculation if a second lidar system probes the same air mass. Also an intercomparison of the AMALi system with an established ground-based Koldewey Aerosol Raman Lidar (KARL) is given.

Stachlewska, I. S.; Neuber, R.; Lampert, A.; Ritter, C.; Wehrle, G.

2010-03-01

35

Initial measurements using a 1.54 micron eyesafe Raman shifted lidar  

NASA Astrophysics Data System (ADS)

A viable, eyesafe, Raman-shifted lidar system operating at 1.54 micron is demonstrated. The system is based on Raman shifting the 1.06 micron output from a Nd:YAG laser to 1.54 micron with a methane cell. System analysis confirmed by initial measurements, indicates that this lidar has the sensitivity to be a useful tool for measuring tropospheric aerosols as well as clouds up to the tropopause with total eye safety.

Patterson, Edward M.; Roberts, David W.; Gimmestad, Gary G.

1989-12-01

36

LIDAR versus satellite-measured optical thickness of a wildfire aerosol  

Microsoft Academic Search

A dual UV, Rayleigh\\/nitrogen Raman LIDAR system was developed for the purpose of profiling aerosols at vertical ranges between 0.025 and 5 km. The 355 nm LIDAR was operated in El Segundo, California during June and July 2008, during a period of intense wildfire activity in Northern California. From the two independent measurements we calculated the particle backscatter, and using

David S. Stoker; Gilda Fathi; Pavel Ionov; Steven M. Beck

2009-01-01

37

Lidar network observation of tropospheric aerosols  

NASA Astrophysics Data System (ADS)

This paper presents the results of recent studies on tropospheric aerosols, including Asian dust and forest fire smoke using the NIES Lidar Network, CALIPSO/CALIOP and chemical transport models. The NIES Lidar Network is a network of two-wavelength (532nm, 1064nm) polarization (532nm) lidars in East Asia. Currently the lidars are continuously operated at about 20 locations in Japan, Korea, China, Mongolia, and Thailand, in cooperation with various research institutes and universities. The network is a part of the Asian Dust Network (ADNet), SKYNET, and the GAW Aerosol Lidar Observation Network (GALION). The data from most of the lidar stations are transferred to NIES in realtime and automatically processed to derive the attenuated backscattering coefficients at 532nm and 1064nm, the volume depolarization ratio at 532nm, and the estimated dust and spherical aerosol extinction coefficients at 532nm. The data from the network are used in various research activities on Asian dust, regional air pollution, and the effects of aerosols on climate and the environment. The data are also used for real-time monitoring (for early warning assessment) of Asian dust. The results of recent studies on long-range transport of Asian dust, optical characteristics of forest fire plumes, aerosol climatology, etc. will be described.

Sugimoto, Nobuo; Matsui, Ichiro; Shimizu, Atsushi; Nishizawa, Tomoaki; Hara, Yukari; Uno, Itsushi

2010-10-01

38

Multi-wavelength Raman lidar, sun photometric and aircraft measurements in combination with inversion models for the estimation of the aerosol optical and physico-chemical properties over Athens, Greece  

NASA Astrophysics Data System (ADS)

A novel procedure has been developed to retrieve, simultaneously, the optical, microphysical and chemical properties of tropospheric aerosols with a multi-wavelength Raman lidar system in the troposphere over an urban site (Athens, Greece: 37.9° N, 23.6° E, 200 m a.s.l.) using data obtained during the European Space Agency (ESA) THERMOPOLIS project, which took place between 15-31 July 2009 over the Greater Athens Area (GAA). We selected to apply our procedure for a case study of intense aerosol layers that occurred on 20-21 July 2009. The National Technical University of Athens (NTUA) EOLE 6-wavelength Raman lidar system has been used to provide the vertical profiles of the optical properties of aerosols (extinction and backscatter coefficients, lidar ratio) and the water vapor mixing ratio. An inversion algorithm was used to derive the mean aerosol microphysical properties (mean effective radius (reff), single-scattering albedo ?) and mean complex refractive index (m)) at selected heights in the 2-3 km height region. We found that reff was 0.14-0.4 (±0.14) ?m, ? was 0.63-0.88 (±0.08) (at 532 nm) and m ranged from 1.44 (±0.10) + 0.01 (±0.01)i to 1.55 (±0.12) + 0.06 (±0.02)i, in good agreement (only for the reff values) with in situ aircraft measurements. The water vapor and temperature profiles were incorporated into the ISORROPIA II model to propose a possible in situ aerosol composition consistent with the retrieved m and ? values. The retrieved aerosol chemical composition in the 2-3 km height region gave a variable range of sulfate (0-60%) and organic carbon (OC) content (0-50%), although the OC content increased (up to 50%) and the sulfate content dropped (up to 30%) around 3 km height; the retrieved low ? value (0.63), indicates the presence of absorbing biomass burning smoke mixed with urban haze. Finally, the retrieved aerosol microphysical properties were compared with column-integrated sun photometer CIMEL data.

Mamouri, R. E.; Papayannis, A.; Amiridis, V.; Müller, D.; Kokkalis, P.; Rapsomanikis, S.; Karageorgos, E. T.; Tsaknakis, G.; Nenes, A.; Kazadzis, S.; Remoundaki, E.

2012-07-01

39

Solar-Blind Raman Lidar.  

National Technical Information Service (NTIS)

This document describes the progress of the NADC Atmospheric Lidar Program funded by the Naval Environmental Prediction Research Facility, Monterey, California, under Program Element 62759N, Project F52553. The objective of this effort is to theoretically...

A. Salik

1983-01-01

40

Multi-wavelength Raman Lidar Measurements For CALIPSO Validation At CNR-IMAA EARLINET Station  

NASA Astrophysics Data System (ADS)

A Raman/elastic lidar for tropospheric aerosol study is operational at CNR-IMAA (40° 36'N, 15° 44'E, 760 m above sea level) since May 2000 in the framework of EARLINET (European Aerosol Research LIdar NETwork), the first lidar network for tropospheric aerosol study on continental scale. This system provides aerosol backscatter coefficient profiles at 1064 nm, and independent measurements of aerosol extinction and backscatter coefficient profiles at 355 and 532 nm. In this way, lidar ratio (i.e. extinction to backscatter ratio) profiles at 355 and 532 nm are also obtained. In addition, the detection of components of backscattered light polarized perpendicular and parallel to the direction of the linearly polarized transmitted laser beam at 532 nm allows the measurements of the aerosol depolarization ratio vertical profiles. High quality multi-wavelength measurements (3 backscatter + 2 extinction) allow the determination of microphysical aerosol properties (refractive index, single-scattering albedo and effective particles radii), while depolarization ratio measurements give information about shape and orientation of aerosolic particles and lidar ratio measurements are important for aerosol characterization. This multi-wavelength system is optimal for the validation of CALIPSO data products: it provides a reference point for depolarization ratio and aerosol backscatter at 532 and 1064 nm measurements with the direct comparison of measurements derived from CALIPSO and our lidar system, furthermore aerosol extinction measurements at 532 nm and 355 nm and backscatter measurements at 355 nm add useful information about microphysical aerosol properties that can be used to improve the retrieval of aerosol backscatter coefficient from pure backscatter lidar. Since 14 June 2006, devoted measurements are performed at CNR-IMAA in coincidence of CALIPSO overpasses (maximum 80 km and 2 hours of spatial and temporal distance). First results of the CNR-IMAA observations for CALIPSO products validation will be shown. ACKNOWLEDGMENTS The financial support of this work by the European Commission under grant RICA-025991 is gratefully acknowledged.

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

2006-12-01

41

Raman lidar profiling of atmospheric water vapor  

NASA Astrophysics Data System (ADS)

Detailed measurements of the distribution of water vapor in the atmosphere are needed for a variety of scientific inquiries, including global climate change and related issues in radiative processes (water vapor is the major greenhouse gas in the atmosphere), and studies of a variety of atmospheric processes such as cloud formation and atmospheric circulation. The Raman lidar is a leading candidate for an instrument capable of the detailed, time- and space-resolved measurements required by these and other studies. We are currently developing two Raman lidar systems. One, which has been under development for several years, is used for our own studies at Sandia. The Sandia lidar system uses an injection-seeded excimer laser to provide a beam with reduced divergence and spectral bandwidth, operated at 308 nm during both nighttime and daytime. The second Raman lidar system under development will have a permanent resident at the Department of Energy's Atmospheric Radiation Measurement program (ARM) Cloud and Radiation Testbed (CART) site near Lamont, Oklahoma. This system is based on a high-power 355-nm laser beam produced by a frequency-tripled Nd:YAG laser.

Goldsmith, J. E. M.; Bisson, Scott E.

1995-05-01

42

North-south cross sections of the vertical aerosol distribution over the Atlantic Ocean from multiwavelength Raman/polarization lidar during Polarstern cruises  

NASA Astrophysics Data System (ADS)

Shipborne aerosol lidar observations were performed aboard the research vessel Polarstern in 2009 and 2010 during three north-south cruises from about 50°N to 50°S. The aerosol data set provides an excellent opportunity to characterize and contrast the vertical aerosol distribution over the Atlantic Ocean in the polluted northern and relatively clean southern hemisphere. Three case studies, an observed pure Saharan dust plume, a Patagonian dust plume east of South America, and a case of a mixed dust/smoke plume west of Central Africa are exemplarily shown and discussed by means of their optical properties. The meridional transatlantic cruises were used to determine the latitudinal cross section of the aerosol optical thickness (AOT). Profiles of particle backscatter and extinction coefficients are presented as mean profiles for latitudinal belts to contrast northern- and southern-hemispheric aerosol loads and optical effects. Results of lidar observations at Punta Arenas (53°S), Chile, and Stellenbosch (34°S), South Africa, are shown and confirm the lower frequency of occurrence of free-tropospheric aerosol in the southern hemisphere than in the northern hemisphere. The maximum latitudinal mean AOT of 0.27 was found in the northern tropics (0- 15°N) in the Saharan outflow region. Marine AOT is typically 0.05 ± 0.03. Particle optical properties are presented separately for the marine boundary layer and the free troposphere. Concerning the contrast between the anthropogenically influenced midlatitudinal aerosol conditions in the 30- 60°N belt and the respective belt in the southern hemisphere over the remote Atlantic, it is found that the AOT and extinction coefficients for the vertical column from 0-5km (total aerosol column) and 1-5km height (lofted aerosol above the marine boundary layer) are a factor of 1.6 and 2 higher at northern midlatitudes than at respective southern midlatitudes, and a factor of 2.5 higher than at the clean marine southern-hemispheric site of Punta Arenas. The strong contrast is confined to the lowermost 3km of the atmosphere.

Kanitz, T.; Ansmann, A.; Engelmann, R.; Althausen, D.

2013-03-01

43

Aerosol plume observations by the ground-based lidar, sunphotometer, and satellite: cases analysis  

NASA Astrophysics Data System (ADS)

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

Wu, Yonghua; Gan, Chuen-Meei; Gross, Barry; Moshary, Fred; Ahmed, Sam

2009-09-01

44

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

45

Lidar monitoring aerosol pollution at industrial regions  

NASA Astrophysics Data System (ADS)

Laser equipment and methodology have been developed to monitor the power of dust sources ejecting aerosol pollution to atmosphere, and the distribution of aerosol mass concentration at regions of large factories. This work is directed to describe lidar technique of atmospheric aerosol monitoring. Technical parameters of lidar stations and results of experimental investigation are presented. The measurements were implemented by the multiwavelength lidar 'Glory-M', which has 7 working wavelengths within the range 0.38-1.0 micrometers , and mobile lidars station (MLS). The lidar design provides measuring the intensity and the depolarization of backscatter signals. Two problems have been considered. The first one is ivnestigating aerosol optical parameter spectra over the boundary atmoshperic layer both at background and industrial regions. The extinction spectra for industrial regions are different from low power, as for background ones. The obtained data will enable one to correct the atmosphere spectra deformation in observing different regions of the Earth from satellites and aircraft. The second problem is invesitigating spatial distribution of dust over regions of industrial centers. The dust flows and power of outbursts have been estimated. The maps of dust mass concentration at the regions of the large factories have been constructed.

Chaikovsky, Anatoly P.; Hutko, I. S.; Ivanov, A. P.; Osipenko, F. P.; Shcherbakov, V. N.; Tauroginskaya, S. B.; Kovalev, A. A.; Samusenko, A. M.

1995-09-01

46

Raman lidar characterization of PBL structure during COPS  

NASA Astrophysics Data System (ADS)

The planetary boundary layer 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 boundary-layer vertical structure and time variability. Aerosols can be dispersed out of the PBL during strong convection or temporary breaks of the capping temperature inversion. 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. Our analysis considers a method based on the first order derivative of the range-corrected elastic signal (RCS), which is a modified version of the method defined by Seibert et al. (2000) and Sicard et al. (2006). The analysis is focused on selected case studies collected by the Raman lidar system BASIL during the Convective and Orographically-induced Precipitation Study (COPS), held in Southern Germany and Eastern France in the period 01 June - 31 August 2007. Measurements were performed by the Raman lidar system BASIL, which was operational in Achern (Black Forest, Lat: 48.64 ° N, Long: 8.06 ° E, Elev.: 140 m). During COPS, BASIL collected more than 500 hours of measurements, distributed over 58 measurement days and 34 intensive observation periods (IOPs), covering both night-time and daytime and the transitions between the two. Therefore BASIL data during COPS represent a unique source of information for the study of the boundary layer structure and evolution. Potential temperature profiles obtained from the radiosonde data were used to get an additional estimate of the boundary layer height. Estimates of the PBL height and structure for specific case studies obtained from the lidar data and their comparison with estimates obtained from the radiosonde data will be illustrated and discussed at the Conference.

Summa, D.; Di Girolamo, P.; Stelitano, D.; Di Iorio, T.

2012-04-01

47

Lidar aerosol backscatter measurements - Systematic, modeling, and calibration error considerations  

NASA Astrophysics Data System (ADS)

Sources of systematic, modeling, and calibration errors that affect the interpretation and calibration of lidar aerosol backscatter data are discussed. The treatment pertains primarily to ground-based pulsed CO2 lidars that probe the troposphere and are calibrated using hard calibration targets. However, a large part of the analysis is relevant to other types of lidar system such as lidars operating at other wavelengths; CW focused lidars; airborne or earth-orbiting lidars; lidars measuring other regions of the atmosphere; lidars measuring nonaerosol elastic or inelastic backscatter; and lidars employing other calibration techniques.

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

1985-11-01

48

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

49

Aerosol Models for the CALIPSO Lidar Inversion Algorithms.  

National Technical Information Service (NTIS)

We use measurements and models to develop aerosol models for use in the inversion algorithms for the Cloud Aerosol Lidar and Imager Pathfinder Spaceborne Observations (CALIPSO). Radiance measurements and inversions of the AErosol RObotic NETwork (AERONET)...

A. H. Omar D. Winkler J. G. Won

2004-01-01

50

Stratospheric aerosol measurements by the Lidar in Space Technology Experiment  

Microsoft Academic Search

The Lidar in Space Technology Experiment (LITE) is a three-wavelength backscatter lidar developed by NASA Langley Research Center to demonstrate and explore the capabilities of space lidar. LITE was flown on space shuttle Discovery in September 1994. Among the primary experimental objectives of LITE was the measurement of stratospheric aerosols. High-quality stratospheric aerosol measurements at 532 nm and 355 nm

Mary T. Osborn; Geoffrey S. Kent; Charles R. Trepte

1998-01-01

51

NASA/GSFC Scanning Raman Lidar Measurements of Water Vapor and Clouds During IHOP.  

National Technical Information Service (NTIS)

The NASA/GSFC Scanning Raman Lidar (SRL) participated in the International H(sub 2)0 Project (IHOP) that occurred in May and June, 2002 in the midwestern part of the U.S. The SRL acquired measurements of water vapor, aerosols, cloud liquid and ice water, ...

D. N. Whiteman B. Demoz P. Di Girolamo J. Comer Z. Wang

2004-01-01

52

Observation of aerosol with a compact lidar over Hefei, China  

NASA Astrophysics Data System (ADS)

A portable compact lidar system was presented in this paper. The measurement results of lidar were compared with the result measured by visibility sensor of vaisala and reliable and Aethalomete of Magee, so the reliable of the lidar system was tested. The experimental results show good agreement. With the changing lidar ratios, the extinction coefficient of aerosols in Hefei was derived.

Liu, Zeng-dong; Liu, Jian-guo; Liu, Wen-qing; Zhao, Xue-song; Huang, Shu-hua; Feng, Weiwei; Xiao, Feng-gang

2008-03-01

53

Capability of Raman lidar for monitoring the variation of atmospheric CO2 profile  

NASA Astrophysics Data System (ADS)

Lidar (Light detection and ranging) has special capabilities for remote sensing of many different behaviours of the atmosphere. One of the techniques which show a great deal of promise for several applications is Raman scattering. The detecting capability, including maximum operation range and minimum detectable gas concentration is one of the most significant parameters for lidar remote sensing of pollutants. In this paper, based on the new method for evaluating the capabilities of a Raman lidar system, we present an evaluation of detecting capability of Raman lidar for monitoring atmospheric CO2 in Hefei. Numerical simulations about the influence of atmospheric conditions on lidar detecting capability were carried out, and a conclusion can be drawn that the maximum difference of the operation ranges caused by the weather conditions alone can reach about 0.4 to 0.5km with a measuring precision within 30ppmv. The range of minimum detectable concentration caused by the weather conditions alone can reach about 20 to 35 ppmv in vertical direction for 20000 shots at a distance of 1 km on the assumption that other parameters are kept constant. The other corresponding parameters under different conditions are also given. The capability of Raman lidar operated in vertical direction was found to be superior to that operated in horizontal direction. During practical measurement with the Raman lidar whose hardware components were fixed, aerosol scattering extinction effect would be a significant factor that influenced the capability of Raman lidar. This work may be a valuable reference for lidar system designing, measurement accuracy improving and data processing.

Zhao, Pei-Tao; Zhang, Yin-Chao; Wang, Lian; Hu, Shun-Xing; Su, Jia; Cao, Kai-Fa; Zhao, Yue-Feng; Hu, Huan-Ling

2008-01-01

54

Saharan dust intrusions in the Mediterranean area: Three years of Raman lidar measurements  

Microsoft Academic Search

A multiyear climatological study of Saharan dust intrusions in the central Mediterranean in terms of aerosol optical parameters vertical profiles is carried out for the first time. Observations are performed at Istituto di Metodologie per l'Analisi Ambientale (IMAA) Raman\\/elastic lidar station located in Tito Scalo, Potenza (40°36'N, 15°44'E), from May 2000 to April 2003, in the framework of European Aerosol

Lucia Mona; Aldo Amodeo; Marco Pandolfi; Gelsomina Pappalardo

2006-01-01

55

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

56

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

57

On retrieval of lidar extinction profiles using Two-Stream and Raman techniques  

NASA Astrophysics Data System (ADS)

The Two-Stream technique employs simultaneous measurements performed by two elastic backscatter lidars pointing at each other to sample into the same atmosphere. It allows for a direct retrieval of the extinction coefficient profile from the ratio of the two involved lidar signals. During a number of Alfred-Wegener-Institute (AWI) campaigns dedicated to Arctic research, the AWI's Polar 2 aircraft with the integrated onboard nadir-pointing Airborne Mobile Aerosol Lidar (AMALi) was utilised. The aircraft flew over a vicinity of Ny Ålesund on Svalbard, where the zenith-pointing Koldewey Aerosol Raman Lidar (KARL) has been located. This experimental approach gave the unique opportunity to retrieve the extinction profiles with a rarely used Two-Stream technique against a well established Raman technique. Both methods were applied to data obtained for clean Arctic conditions during the Arctic Study of Tropospheric clouds and Radiation (ASTAR 2004) campaign, and slightly polluted Arctic conditions during the Svalbard Experiment (SvalEx 2005) campaign. Successful comparison of both evaluation tools in different measurement conditions demonstrates sensitivity and feasibility of the Two-Stream method to obtain particle extinction and backscatter coefficients profiles without assumption of their relationship (lidar ratio). The method has the potential to serve as an extinction retrieval tool for KARL or AMALi simultaneous observations with the space borne CALIPSO lidar overpasses during the ASTAR 2007.

Stachlewska, I. S.; Ritter, C.

2010-03-01

58

Lidar observations of the Pinatubo aerosol layer at Thule, Greenland  

SciTech Connect

This paper summarizes lidar measurements from Thule Greenland made during EASOE. The lidar was able to track aerosols, primarily of volcanic origin, through the winter. Above 18 km the aerosol content was strongly dependent upon the location of the vortex, and did not show a substantial increase until the vortex broke up.

Di Girolamo, P.; Cacciani, M.; Sarra, A. di; Fiocco, G.; Fua, D. (Universita La Sapienza, Rome (Italy))

1994-06-22

59

Combined lidar measurements of cloud properties, stratospheric, aerosols, and ozone profiles over Geesthacht(53.4 degrees N, 10.4 degrees E)  

Microsoft Academic Search

A combined Raman and elastic-backscatter lidar for independent profiling of tropospheric aerosols, moisture, and ozone and aerosol parameters is presented. GKSS operates this advanced Raman lidar at Geesthacht, Germany. First routine ozone measurements were taken between February and April 1995, Simultaneously with the European SESAME (Second European Stratospheric Arctic and Mid-latitude Experiment) campaign. The transmitter contains two lasers, a XeCl

Marcus Serwazi; Jens Reichardt; Claus Weitkamp

1995-01-01

60

Aerosol models for the CALIPSO lidar inversion algorithms  

Microsoft Academic Search

We use measurements and models to develop aerosol models for use in the inversion algorithms for the Cloud Aerosol Lidar and Imager Pathfinder Spaceborne Observations (CALIPSO). Radiance measurements and inversions of the AErosol RObotic NETwork (AERONET1, 2) are used to group global atmospheric aerosols using optical and microphysical parameters. This study uses more than 10 5 records of radiance measurements,

Ali H. Omar; David Winker; Jae-Gwang Won

61

Miniature aerosol lidar for automated airborne application  

NASA Astrophysics Data System (ADS)

The Russian Mjasishchev 55 (M-55) <> high altitude aircraft is dedicated to atmospheric science research. It carries onboard a set of mutually complementary instruments for in- situ and remote sensing. The Green Miniature Aerosol Lidar (GMAL) has been developed to operate automatically on this platform. It is a short-range, zenith-looking, depolarization elastic-backscatter lidar based on a 532 nm micro-chip Nd-YAG laser. Compact, low-power consuming, it stands in a 27-litre isolating and warmed hermetic box. The device participated successfully to an extended test campaign in Italy during December 1998 and January 1999, and to the APE/THESEO campaign in the Indian Ocean during February-March 1999. It also showed capabilities for unattended measurement of the low troposphere from the ground. Description of the instrument and preliminary results are presented.

Matthey, Renaud; Mitev, Valentin; Mileti, Gaetano; Makarov, Vladislav S.; Turin, Alexander V.; Morandi, Marco; Santacesaria, Vincenzo

2000-09-01

62

Micropulse lidar for aerosol and cloud measurement  

NASA Astrophysics Data System (ADS)

A lidar system employing a diode laser pumped Nd:YLF laser and photon counting technique is described for use in automated cloud and aerosol measurements. A Nd:YLF laser provides 523 nm 10 (mu) J/pulse energy at 2500 Hz repetition rate. A coaxial configuration is used for transmitting laser pulse and receiving the signal with a 0.2 m Schmidt-Cassegrain telescope. An avalanche photodiode is used for back scattered photon counting in Geiger mode. This micro pulse lidar (MPL) is capable to detect subvisible cirrus and boundary layer within 10 second averaging time. Also the MPL takes back scattered signal at four different spatial resolutions of 30 m, 75 m, 150 m, and 300 m to meet various user requirements. The detected signal is processed and displayed on a personal computer. The 32 bit data processing software is running on the Window 95 platform.

Hwang, In H.; Lokos, Sandor; Kim, Jin

1997-05-01

63

Raman lidar for retrieval of water-vapour and temperature profiles in Eureka, Nunavut  

NASA Astrophysics Data System (ADS)

A Raman lidar has been installed in Eureka, Nunavut (79°59'N, 85°56'W) to study the thermodynamic and radiative environments in the High Arctic, as part of the Canadian Network for the Detection of Atmospheric Change. The lidar was designed to profile tropospheric water-vapour as well as aerosols, clouds and temperature from near-ground to the lower-stratosphere. This thesis focuses on the commissioning of the lidar, as well as the water-vapour and temperature retrievals. For optimal data quality, the data acquisition hardware was characterized and the settings for normal operation established. Performance modeling of the water-vapour and temperature retrieval sensitivities as a function of specific technical considerations is presented. The results were used during the commissioning of the lidar for in situ retrieval sensitivity optimization. Finally, the calibration techniques, results and uncertainties are presented for both the water-vapour and temperature retrievals.

Doyle, Jonathan G.

64

Analysis of influence of atmosphere extinction to Raman lidar monitoring CO2 concentration profile  

NASA Astrophysics Data System (ADS)

Lidar (Light detection and ranging) system monitoring of the atmosphere is a novel and powerful technique tool. The Raman lidar is well established today as a leading research tool in the study of numerous important areas in the atmospheric sciences. In this paper, the principle of Raman lidar technique measurement CO2 concentration profile is presented and the errors caused by molecular and aerosol extinction for CO2 concentration profile measurement with Raman lidar are also presented. The standard atmosphere extinction profile and 'real-time' Hefei area extinction profile are used to conduct correction and the corresponding results are yielded. Simulation results with standard atmosphere mode correction indicate that the errors caused by molecule and aerosol extinction should be counted for the reason that they could reach about 8 ppm and 5 ppm respectively. The relative error caused by Hefei area extinction correction could reach about 6%. The errors caused by the two components extinction influence could produce significant changes for CO2 concentration profile and need to be counted in data processing which could improve the measurement accuracies.

Zhao, Pei-Tao; Zhang, Yin-Chao; Wang, Lian; Zhao, Yue-Feng; Su, Jia; Fang, Xin; Cao, Kai-Fa; Xie, Jun; Du, Xiao-Yong

2007-08-01

65

On retrieval of lidar extinction profiles using Two-Stream and Raman techniques  

NASA Astrophysics Data System (ADS)

The Two-Stream technique employes simultaneous measurements performed by two elastic backscatter lidars aiming at each other to sample into the same atmosphere. It allows for a direct retrieval of the extinction coefficient profile from the ratio of the two involved lidar signals. During a few Alfred-Wegener-Institute's (AWI) campaigns dedicated to the Arctic research, the AWI's Polar 2 aircraft with the integrated onboard nadir-aiming Airborne Mobile Merosol Lidar (AMALi) overflew a vicinity of Ny Ålesund on Svalbard, where the zenith-aiming Koldewey Aerosol Raman Lidar (KARL) has been located. This experimental approach gave a unique opportunity to retrieve the extinction profiles with rather rarely used Two-Stream technique against the well established Raman technique. Both methods were applied to data obtained for a clean Arctic conditions during the Arctic Study of Tropospheric clouds and Radiation (ASTAR 2004) campaign and a slightly polluted Arctic conditions during the Svalbard Experiment (SvalEx 2005) campaign. Successful intercomparison of both evaluation tools in a different measurement conditions demonstrates sensitivity and feasibility of the Two-Stream method to obtain particle extinction and backscatter coefficients profiles without assumption of their relationship (lidar ratio). The method has a potential to serve as an extinction retrieval tool for KARL or AMALi simultaneous observations with the spaceborne CALYPSO lidar taken during the ASTAR 2007.

Stachlewska, I. S.; Ritter, C.

2009-09-01

66

Aerosol measurements with a combined elastic/non-elastic backscatter lidar in Beijing  

NASA Astrophysics Data System (ADS)

In order to reach a green Olympics in 2008, an unprecedented environmental experiment jointly launched by the Beijing municipal government and the Chinese Academy of Sciences (CAS) was carried out. AIOFM (Anhui Institute of Optics and Fine Mechanics Experiment) took part in the campaign with an elastic/non-elastic lidar to measure the aerosol distribution and the boundary layer in summer in Beijing. With the combining solution of the Raman lidar and the elastic lidar equation, the important optical parameters of the aerosols (extinction coefficient, backscatter coefficients thus the lidar ratio) were attained. The lidar ratio on July 22 varied from 10sr to 30sr. Since the vertical distribution of the lidar ratio demonstrate different microphysical characteristics in the lower and upper parts of the cloud, so probably the cirrus with the mean lidar ratio of 25sr at the height of 6km can be assumed. On the other hand, a well-mixed boundary layer was observed. Taking into account the effects of the multiple scattering (5%-10%),we obtain a single-scattering optical depth of 0.15.The boundary layer also offered the explanation of the steady ozone concentration measured by the DOAS system at the same position of the observing site.

Chen, Zhenyi; Liu, Wenqing; Zhang, Yujun; Zhao, Nanjing; He, Junfeng; Ruan, Jun

2009-07-01

67

mESY LIDAR - a new cost-effective, versatile and powerful lidar configuration for tropospheric aerosols, clouds and water vapor investigations  

NASA Astrophysics Data System (ADS)

In the context of remote sensing tools development for the monitoring of relevant atmospheric parameters triggering crucial processes in troposphere this work is presenting a new mini lidar system i.e mESY LIDAR. The basic configuration of this lidar is dedicated for tropospheric (100m to 12-15 Km ASL) aerosols and clouds high temporal (minutes) and spatial resolution (meters) investigation. Based on powerful Nd:YAG 30 Hz pulsed laser (35 mJ at 355 nm, 100 mJ at 532 nm, 200 mJ at 1064 nm), a 16" Newtonian telescope and a new easy up-gradable opto-mechanics the mESY LIDAR is a cost-effective and powerful equipment useful both for atmospherically researches and didactic - educational - lidar training activities also. The basic configuration (two detection channels) may be used either for depolarization studies (at 532, 355 or 1064nm) or the choice of two elastic and is ideal for continuous monitoring of planetary boundary layer dynamic i.e. PBL. The Raman Nitrogen at 387 nm and water vapor channels at 408 nm may be upgraded easily. The design of this lidar, developed within the research partnership between Switzerland and Romanian academic - private partnership institutions, is the standard lidar proposed for ROLINET (ROmanian LIdar NETwork) project with the final aim to be integrated in the EARLINET (European Aerosol Research LIdar NETwork) in 2010.

Cazacu, M. M.; Ristori, P.; Tudose, O.; Balanici, A.; Nicolae, D.; Ristici, V.; Balin, D.; Balin, I.

2009-04-01

68

Retrieval of aerosol mass concentration from elastic lidar data  

NASA Astrophysics Data System (ADS)

Agricultural aerosol sources can contribute significantly to air pollution in many regions of the country. Characterization of the aerosol emissions of agricultural operations is required to establish a scientific basis for crafting regulations concerning agricultural aerosols. A new lidar instrument for measuring aerosol emissions is described, as well as two new algorithms for converting lidar measurements into aerosol concentration data. The average daily aerosol emission rate is estimated from a dairy using lidar. The Aglite Lidar is a portable scanning lidar for mapping the concentration of particulate matter from agricultural and other sources. The instrument is described and performance and lidar sensitivity data are presented. Its ability to map aerosol plumes is demonstrated, as well as the ability to extract wind-speed information from the lidar data. An iterative least-squares method is presented for estimating the solution to the lidar equation. The method requires a priori knowledge of aerosol relationships from point sensors. The lidar equation is formulated and solved in vector form. The solution is stable for signals with extremely low signal-to-noise ratios and for signals at ranges far beyond the boundary point. Another lidar algorithm is also presented as part of a technique for estimating aerosol concentration and particle-size distribution. This technique uses a form of the extended Kalman filter, wherein the target aerosol is represented as a linear combination of basis-aerosols. For both algorithms, the algorithm is demonstrated using both synthetic test data and field measurements of biological aerosol simulants. The estimated particle size distribution allows straightforward calculation of parameters such as volume-fraction concentration and effective radius. Particulate matter emission rates from a dairy in the San Joaquin Valley of California were investigated during June 2008. Vertical particulate matter concentration profiles were measured both upwind and downwind of the facility using lidar, and a mass balance technique was used to estimate the average emission rate. Emission rates were also estimated using an inverse modeling technique coupled with the filter-based measurements. The concentrations measured by lidar and inverse modeling are of similar magnitude to each other, as well as to those from studies with similar conditions.

Marchant, Christian C.

69

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

70

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

Microsoft Academic Search

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

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

2009-01-01

71

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

72

Design and performance measurements of an airborne aerosol backscatter lidar  

Microsoft Academic Search

The global winds measurement application of coherent Doppler lidar requires intensive study of the global climatology of atmospheric aerosol backscatter at infrared wavelengths. An airborne backscatter lidar is discussed, which has been developed to measure atmospheric backscatter profiles at CO2 laser wavelengths. The instrument characteristics and representative flight measurement results are presented.

Robert T. Menzies; David M. Tratt; Alan M. Brothers; Stephen H. Dermenjian; Carlos Esproles

1990-01-01

73

Shipborne measurements with a modular multipurpose mobile lidar system for tropospheric and stratospheric aerosol observations  

NASA Astrophysics Data System (ADS)

In our contribution water vapor and aerosol measurements with a new modular two wavelength Rayleigh Raman lidar instrument are described. A comparison of the data with radiosonde data are shown and the results discussed. The new mobile aerosol Raman lidar (MARL) is able to measure aerosol backscatter and extinction coefficient as well as depolarization in the altitude range 5 to 50 km. The system is operational since July 1996 and participated at the ALBATROSS (atmospheric chemistry and lidar studies above the Atlantic Ocean related to ozone and other trace gases in the tropo and stratosphere) campaign aboard the German research vessel Polarstern on a cruise from Bremerhaven, Germany to Punta Quilla, Argentina in October/November 1996. Key parts of the lidar system include a frequency doubled and tripled Nd:YAG laser, a large receiving telescope mirror (1.15 m diameter) and a sophisticated polychromator. The system's power aperture product is more than 9 Wm2 on each wavelength (532 nm and 355 nm). The instrument is installed in a standard 20 ft ISO container and is operational in polar as well as tropical environments wherever a supply with electrical power is available.

Schaefer, Juergen; Schrems, Otto; Beyerle, Georg; Hofer, Bernd; Mildner, Wolfgang; Theopold, Felix A.

1997-05-01

74

Aerosol measurements by lidar in the nocturnal boundary layer  

NASA Astrophysics Data System (ADS)

A lidar system capable to perform simultaneous measurements of atmospheric water vapor and aerosols have been developed in Tito Scalo, in the context of a cooperation between Universita della Baslicata and Istituo di Metodolgoie Avanzate di Analisis Ambientale. Aerosol observations by lidar in the nocturnal boundary laser (NBL) have been performed in the period 20 January- 20 February 1997, Radiosondes were launched during the measurement campaign simultaneously to lidar operation. Lidar observations have been sued to retrieve aerosol properties and dimensional characteristics. Aerosol sizes are determined by comparison measured and theoretical values of (beta) A,723(z)/(beta) A,355(z), with (beta) A,723(z) and (beta) A,355(z) being the aerosol backscattering coefficient at 723.37 and 355 nm, respectively. Furthermore, lidar and radiosonde data have been compared in order to study the NBL vertical structure and evolution. Lidar measurements of (beta) A,723(z) are compared with simultaneous radiosonde data expressed in terms of potential temperature and relative humidity, with particular emphasis on the estimate of the residual layer height from both lidar and radiosonde data. Results from the present measurements campaign will be reported and discussed in this presentation.

Di Girolamo, Paolo; Ambrico, Paolo F.; Amodeo, Aldo; Boselli, Antonella; Pappalardo, Gelsomina

2000-02-01

75

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

76

Extinction-to-backscatter ratio of Asian dust observed with high-spectral-resolution lidar and Raman lidar  

Microsoft Academic Search

Extinction-to-backscatter ratio or lidar ratio is a key parameter in the issue of backscatter-lidar inversions. The lidar ratio of Asian dust was observed with a high-spectral-resolution lidar and a combined Raman elastic-backscatter lidar during the springs of 1998 and 1999. The measured values range from 42 to 55 sr in most cases, with a mean of 51 sr. These values

Zhaoyan Liu; Nobuo Sugimoto; Toshiyuki Murayama

2002-01-01

77

Multi-wavelength Raman lidar observations of the Eyjafjallajökull volcanic cloud over Potenza, southern Italy  

NASA Astrophysics Data System (ADS)

During the eruption of Eyjafjallajökull in April-May 2010 multi-wavelength Raman lidar measurements were performed at the CNR-IMAA Atmospheric Observatory (CIAO), whenever weather conditions permitted observations. A methodology both for volcanic layer identification and accurate aerosol typing has been developed. This methodology relies on the multi-wavelength Raman lidar measurements and the support of long-term lidar measurements performed at CIAO since 2000. The aerosol mask for lidar measurements performed at CIAO during the 2010 Eyjafjallajökull eruption has been obtained. Volcanic aerosol layers were observed in different periods: 19-22 April, 27-29 April, 8-9 May, 13-14 May and 18-19 May. A maximum aerosol optical depth of about 0.12-0.13 was observed on 20 April, 22:00 UTC and 13 May, 20:30 UTC. Volcanic particles were detected at low altitudes, in the free troposphere and in the upper troposphere. Occurrences of volcanic particles within the PBL were detected on 21-22 April and 13 May. A Saharan dust event was observed on 13-14 May: dust and volcanic particles were simultaneously detected at CIAO at separated different altitudes as well as mixed within the same layer. Lidar ratios at 355 and 532 nm, the Ångström exponent at 355/532 nm, the backscatter-related Ångström exponent at 532/1064 nm and the particle linear depolarization ratio at 532 nm measured inside the detected volcanic layers are discussed. The dependence of these quantities on relative humidity has been investigated by using co-located microwave profiler measurements. The measured values of these intensive parameters indicate the presence of volcanic sulfates/continental mixed aerosol in the volcanic aerosol layers observed at CIAO. In correspondence of the maxima observed in the volcanic aerosol load on 19-20 April and 13 May, different values of intensive parameters were observed. Apart from the occurrence of sulfate aerosol, these values indicate also the presence of some ash which is affected by the aging during transport over Europe.

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

2012-02-01

78

Influence of humidified aerosol on lidar depolarization observed during SHEBA  

NASA Astrophysics Data System (ADS)

Lidar depolarization measurements of mixed-phase Arctic clouds can provide information about ice habits and the relative amounts of liquid and ice hydrometeors. Lidar measurements taken under the base of a mixed-phase stratocumulus deck during the SHEBA campaign show regions with surprisingly low depolarization despite the absence of cloud drops or liquid-phase precipitation. Using forward lidar computations based on large-eddy simulations with size-resolved microphysics, we show that the presence of humidified aerosol can very well explain the distribution of the observed depolarization values. Results indicate that humidified aerosol must be taken into account when interpreting lidar depolarization measurements under conditions such as those observed during SHEBA. We also explore the range of conditions under which haze particles complicate the interpretation of lidar depolarization.

Fridlind, A. M.; van Diedenhoven, B.; Ackerman, A. S.

2009-12-01

79

Application of resonance Raman LIDAR for chemical species identification  

SciTech Connect

BNL has been developing a remote sensing technique for the detection of atmospheric pollutants based on the phenomenon of resonance Raman LIDAR that has also incorporated a number of new techniques/technologies designed to extend it`s performance envelope. When the excitation frequency approaches an allowed electronic transition of the molecule, an enormous enhancement of the inelastic scattering cross-section can occur, often up to 2 to 4 orders-of-magnitude, and is referred to as resonance Raman (RR), since the excitation frequency is in resonance with an allowed electronic transition. Exploitation of this enhancement along with new techniques such as pattern recognition algorithms to take advantage of the spectral fingerprint and a new laser frequency modulation technique designed to suppress broadband fluorescence, referred to as Frequency modulated Excitation Raman Spectroscopy (FreMERS) and recent developments in liquid edge filter technology, for suppression of the elastic channel, all help increase the overall performance of Raman LIDAR.

Chen, C.L.; Heglund, D.L.; Ray, M.D.; Harder, D.; Dobert, R.; Leung, K.P.; Wu, M.; Sedlacek, A.

1997-07-01

80

Lidar observations of the stratospheric aerosol layer over Kingston, Jamaica  

Microsoft Academic Search

Results are presented from an intensive study of the stratospheric aerosol layer over Kingston, Jamaica, made in 1978-79, using a ruby lidar system. The aerosol layer is found to extend up to an altitude of about 35 km, with the layer maximum varying between 20 and 26 km. Comparison has been made of the principal layer characteristics with those obtained

M. T. Philip; G. S. Kent; M. T. Ottway

1985-01-01

81

Lidar, nephelometer, and in situ aerosol experiments in  

Microsoft Academic Search

During August 1992, a complex aerosol and optical experiment was performed at Egbert, Ontario, Canada. In situ data from Berner impactors, three active scattering aerosol spectrometer probes, a differential mobility analyzer, filter, and denuder samples were intercompared with optical measurements from a nephelometer and a lidar. A haze event during the study period has been modeled using the measured in

Raymond M. Hoff; L. Guise-Bagley; R. M. Staebler; H. A. Wiebe; J. Brook; B. Georgi

1996-01-01

82

Development of a scanning, solar-blind, water Raman lidar  

Microsoft Academic Search

The need for an instrument capable of measuring water-vapor fluxes over mixed canopy and large areas has long been recognized. Such a device would greatly enhance the study of evapotranspiration processes and has great practical value for water management. To address this problem, a scanning water Raman lidar has been designed and constructed. Analytical methods have also been developed to

William E. Eichinger; Daniel I. Cooper; Fred L. Archuletta; Douglas E. Hof; David B. Holtkamp; Robert R. Karl Jr.; Charles R. Quick Jr.; Joseph J. Tiee

1994-01-01

83

Raman Lidar Profiles–Temperature (RLPROFTEMP) Value-Added Product  

SciTech Connect

The purpose of this document is to describe the Raman Lidar Profiles–Temperature (RLPROFTEMP) value-added product (VAP) and the procedures used to derive atmospheric temperature profiles from the raw RL measurements. Sections 2 and 4 describe the input and output variables, respectively. Section 3 discusses the theory behind the measurement and the details of the algorithm, including calibration and overlap correction.

Newsom, RK; Sivaraman, C; McFarlane, SA

2012-10-31

84

Uniwavelength lidar sensitivity to spherical aerosol microphysical properties for the interpretation of Lagrangian stratospheric observations  

NASA Astrophysics Data System (ADS)

The determination of stratospheric particle microphysical properties from multiwavelength lidar, including Rayleigh and/or Raman detection, has been widely investigated. However, most lidar systems are uniwavelength operating at 532 nm. Although the information content of such lidar data is too limited to allow the retrieval of the full size distribution, the coupling of two or more uniwavelength lidar measurements probing the same moving air parcel may provide some meaningful size information. Within the ORACLE-O3 IPY project, the coordination of several ground-based lidars and the CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation) space-borne lidar is planned during measurement campaigns called MATCH-PSC (Polar Stratospheric Clouds). While probing the same moving air masses, the evolution of the measured backscatter coefficient (BC) should reflect the variation of particles microphysical properties. A sensitivity study of 532 nm lidar particle backscatter to variations of particles size distribution parameters is carried out. For simplicity, the particles are assumed to be spherical (liquid) particles and the size distribution is represented with a unimodal log-normal distribution. Each of the four microphysical parameters (i.e. log-normal size distribution parameters, refractive index) are analysed separately, while the three others are remained set to constant reference values. Overall, the BC behaviour is not affected by the initial values taken as references. The total concentration (N0) is the parameter to which BC is least sensitive, whereas it is most sensitive to the refractive index (m). A 2% variation of m induces a 15% variation of the lidar BC, while the uncertainty on the BC retrieval can also reach 15%. This result underlines the importance of having both an accurate lidar inversion method and a good knowledge of the temperature for size distribution retrieval techniques. The standard deviation ([sigma]) is the second parameter to which BC is most sensitive to. Yet, the impact of m and [sigma] on BC variations is limited by the realistic range of their variations. The mean radius (rm) of the size distribution is thus the key parameter for BC, as it can vary several-fold. BC is most sensitive to the presence of large particles. The sensitivity of BC to rm and [sigma] variations increases when the initial size distributions are characterized by low rm and large [sigma]. This makes lidar more suitable to detect particles growing on background aerosols than on volcanic aerosols.

Jumelet, Julien; David, Christine; Bekki, Slimane; Keckhut, Philippe

2009-01-01

85

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

86

Raman Lidar Profiles Best Estimate Value-Added Product Technical Report  

SciTech Connect

The ARM Raman lidars are semi-autonomous ground-based systems that transmit at a wavelength of 355 nm with 300 mJ, {approx}5 ns pulses, and a pulse repetition frequency of 30Hz. Signals from the various detection channels are processed to produce time- and height-resolved estimates of several geophysical quantities, such as water vapor mixing ratio, relative humidity, aerosol scattering ratio, backscatter, optical depth, extinction, and depolarization ratio. Data processing is currently handled by a suite of six value-added product (VAP) processes. Collectively, these processes are known as the Raman Lidar Profiles VAP (RLPROF). The top-level best-estimate (BE) VAP process was introduced in order to bring together the most relevant information from the intermediate-level VAPs. As such, the BE process represents the final stage in data processing for the Raman lidar. Its principal function is to extract the primary variables from each of the intermediate-level VAPs, perform additional quality control, and combine all of this information into a single output file for the end-user. The focus of this document is to describe the processing performed by the BE VAP process.

Newson, R

2012-01-18

87

Inter-comparison of lidar and ceilometer retrievals for aerosol and Planetary Boundary Layer profiling over Athens, Greece  

NASA Astrophysics Data System (ADS)

This study presents an inter-comparison of two active remote sensors (lidar and ceilometer) in determining the structure of the Planetary Boundary Layer (PBL) and in retrieving tropospheric aerosol vertical profiles over Athens, Greece. This inter-comparison was performed under various strongly different aerosol concentrations (urban air pollution, biomass burning and Saharan dust event), implementing two different lidar systems (one portable Raymetrics S.A. lidar system running at 355 nm and one multi-wavelength Raman lidar system running at 355 nm, 532 nm and 1064 nm) and one CL31 Vaisala S.A. ceilometer (running at 910 nm). To convert the ceilometer data to data having the same wavelengths as those from the lidar, the backscatter-related Ångström exponent was estimated using ultraviolet multi-filter radiometer (UV-MFR) data. The inter-comparison was based on two parameters: the mixing layer structure and height determined by the presence of the suspended aerosols and the aerosol backscatter coefficient. Additionally, radiosonde data were used to derive the PBL height. In general a good agreement is found between the ceilometer and the lidar techniques in both inter-compared parameters in the height range from 500 m to 5000 m, while the limitations of each instrument are also examined.

Tsaknakis, G.; Papayannis, A.; Kokkalis, P.; Amiridis, V.; Kambezidis, H. D.; Mamouri, R. E.; Georgoussis, G.; Avdikos, G.

2011-01-01

88

Transport processes as manifested in satellite and lidar aerosol measurements  

NASA Astrophysics Data System (ADS)

A large increase in stratospheric aerosol data has become available recently from the SAM II and SAGE satellite sensors and the impetus from increased volcanic perturbations. Six years of SAM II and nearly 3 years of SAGE measurements have been accumulated. The increase in large volcanic eruptions since 1979 has caused an acceleration of new data sets from worldwide lidars and airborne lidar campaigns and from various airborne in situ measurements. The SAM II and SAGE data sets show the tropical stratosphere as a source for background stratospheric aerosols, and midlatitudes as a possible sink. Analyses of SAM II data show that the aerosol within the northern wintertime polar vortex becomes isolated from the outside. Subsidence occurs within the vortex, changing the vertical aerosol distribution over the winter period. SAM II and SAGE data show that the aerosol is transported in the stratosphere from low to high latitudes in wintertime. Entry regions of tropospheric air in the Tropics are also evident in the SAGE data as shown by stratospheric cirrus clouds being formed well above the local tropopause. Nature has provided over the past 5 years a number of large volcanic eruptions which spewed tons of new aerosol into the stratosphere. These eruptions have occurred at various latitudes which allow transport differences to be studied. Satellite and lidar aerosol data will be used to describe the stratospheric motions of aerosols produced after these violet volcanic eruptions.

McCormick, M. P.

1985-12-01

89

Lidar observations of the stratospheric aerosol layer over Kingston, Jamaica  

NASA Astrophysics Data System (ADS)

Results are presented from an intensive study of the stratospheric aerosol layer over Kingston, Jamaica, made in 1978-79, using a ruby lidar system. The aerosol layer is found to extend up to an altitude of about 35 km, with the layer maximum varying between 20 and 26 km. Comparison has been made of the principal layer characteristics with those obtained from other lidar and from direct measurements. Short-term fluctuations in the layer, occurring over a few hours or days, have been studied and are believed to be caused by the movement of irregularities in aerosol concentration. The long-term lidar record from 1965-79 is presented, showing the fluctuating volcanic influence during this period.

Philip, M. T.; Kent, G. S.; Ottway, M. T.

1985-05-01

90

A study on the use of radar and lidar for characterizing ultragiant aerosol  

NASA Astrophysics Data System (ADS)

19 April to 19 May 2010, volcanic aerosol layers originating from the Eyjafjallajökull volcano were observed at the Institute of Methodologies for Environmental Analysis of the National Research Council of Italy Atmospheric Observatory, named CIAO (40.60°N, 15.72°E, 760 m above sea level), in Southern Italy with a multiwavelength Raman lidar. During this period, ultragiant aerosols were also observed at CIAO using a colocated 8.45 mm wavelength Doppler radar. The Ka-band radar signatures observed in four separate days (19 April and 7, 10, and 13 May) are consistent with the observation of nonspherical ultragiant aerosols characterized by values of linear depolarization ratio (LDR) higher than -4 dB. Air mass back trajectory analysis suggests a volcanic origin of the ultragiant aerosols observed by the radar. The observed values of the radar reflectivity (Ze) are consistent with a particle effective radius (r) larger than 50-75 µm. Scattering simulations based on the T-matrix approach show that the high LDR values can be explained if the observed particles have an absolute aspect ratio larger than 3.0 and consist of an internal aerosol core and external ice shell, with a variable radius ratio ranging between 0.2 and 0.7 depending on the shape and aspect ratio. Comparisons between daytime vertical profiles of aerosol backscatter coefficient (?) as measured by lidar and radar LDR reveal a decrease of ? where ultragiant particles are observed. Scattering simulations based on Mie theory show how the lidar capability in typing ultragiant aerosols could be limited by low number concentrations or by the presence of an external ice shell covering the aerosol particles. Preferential vertical alignment of the particles is discussed as another possible reason for the decrease of ?.

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

2013-09-01

91

Combined Raman Lidar and DIAL Sounding of Water Vapour and Temperature at the NDACC Station Zugspitze  

NASA Astrophysics Data System (ADS)

The primary greenhouse gas water vapour has moved into the focus of lidar sounding within the Network for the Detection of Atmosperhic Compostion Change (NDACC). Lidar systems with an operating range reaching at least the tropopause region are asked for, with some future extension into the stratosphere. As a first step, we installed in 2003 a powerful differential-absorption lidar (DIAL) at the Schneefernerhaus high-altitude station next to the Zugspitze summit (Germany) [Vogelmann and Trickl, 2008]. This lidar system, located at 2675 m a.s.l., provides water-vapour profiles in the entire free troposphere above 3 km with high vertical resolution and an accuracy of about 5 % up to 8 km without observable bias. Most importantly, due to the high sensitivity of the DIAL technique this wide operating range is also achieved during daytime and under dry conditions. In a parallel contribution we present examples from the routine measurements of this lidar system during the past three years. The results reflect the extreme variability of the free-tropospheric water-vapour concentration, caused by the rich tropospheric dynamics. The system is capable of quantititatively detecting relative humidities of 0 to 2 % in layers of stratospheric origin even just 300 m wide. Due to the very low stratospheric water-vapour mixing ratio of about 5 ppm an extension of the lidar sounding of H2O into the stratosphere is a highly demanding task. Our solution is a particularly big Raman lidar system, which is currently under development at the Schneefernerhaus. By using a 350-W xenon-chloride laser system and a 1.5-m-diameter receiver we hope to extend for the first time the humidity measurements to almost 30 km during nighttime (as extrapolated from results by Leblanc et al. [2004], Whiteman et al. [2008]). We expect that this system is going to fill the existing gap for accurate vertically resolved ground-based routine measurements of water vapour in the lower stratosphere. At the same time the sensitivity for water vapour around the tropopause will be enhanced.One important feature is the calibration of the Raman lidar with the DIAL measurements in the same laboratory, which will result in a good long-term stability. Our first, quite ambitious goal is to achieve narrow-band and polarized operation of the powerful excimer laser that is normally used for industrial production. At the meeting, we will present the system layout and first results on the laser development. In addition, the new lidar will provide temperature profiles up to more than 80 km, based on Raman and Rayleigh methods. The measurements of both quantities are seen as an important step towards an experimental approach to climate research, which will be complemented by recording the spectrally resolved thermal radiation of the sky in the near future. References: H. Vogelmann, T. Trickl, Wide-range sounding of free-tropospheric water vapor with a differential-absorption lidar (DIAL) at a high-altitude station, Appl. Opt. 47 (2008), 2116-2132 T. Leblanc, I. S. McDermid, D. A. Haner, T. D. Walsh, A High-capability Raman Lidar for Upper Tropospheric and Lower Stratospheric Water Vapor Measurements, p. 447-450 in: Reviewed and Revised Papers Presented at the 22nd International Laser Radar Conference, G. Pappalardo, A. Amodeo, Eds., ESA Publications Division (Noordwijk, The Netherlands, 2004), ISBN 92-9092-872-7 D. N. Whiteman, et al., Airborne and Ground-Based Measurements of Water Vapor and Aerosols Using a High-Performance Raman Lidar, pp. 87-90 in: Reviewed and Revised Papers Presented at the 24th International Laser Radar Conference, M. Hardesty, S. Mayor, Eds., NOAA (Boulder, U.S.A., 2008), ISBN 978-0-615-21489-4

Klanner, Lisa; Trickl, Thomas; Vogelmann, Hannes

2010-05-01

92

Daytime Raman lidar profiling of atmospheric water vapor  

SciTech Connect

Detailed measurements of the distribution of water vapor in the atmosphere are needed for a variety of scientific inquiries, including global climate change and related issues in radiative processes (water vapor is the major greenhouse gas in the atmosphere), and studies of a variety of atmospheric processes such as cloud formation and atmospheric circulation. The Raman lidar is a leading candidate for an instrument capable of the detailed, time- and space-resolved measurements required by these and other studies.

Goldsmith, J.E.M.; Bisson, S.E.

1994-08-01

93

Daytime Raman lidar profiling of atmospheric water vapor  

NASA Astrophysics Data System (ADS)

Detailed measurements of the distribution of water vapor in the atmosphere are needed for a variety of scientific inquiries, including global climate change and related issues in radiative processes (water vapor is the major greenhouse gas in the atmosphere), and studies of a variety of atmospheric processes such as cloud formation and atmospheric circulation. The Raman lidar is a leading candidate for an instrument capable of the detailed, time- and space-resolved measurements required by these and other studies.

Goldsmith, J. E. M.; Bisson, S. E.

94

Effective Lidar Ratios of Dense Dust Aerosol Layers over North Africa Observed by the CALIPSO Lidar  

NASA Astrophysics Data System (ADS)

The Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite, a joint US and French mission, was launched three years ago to provide new insight into the role that clouds and aerosols play in regulating Earth's weather, climate, and air quality. A key instrument on board the CALIPSO payload is a two-wavelength, polarization-sensitive backscatter lidar. With its capabilities of depolarization ratio measurement and high resolution profiling, the CALIPSO lidar provides a unique opportunity to study the dust aerosol globally. Currently, a cloud and aerosol discrimination (CAD) algorithm that incorporates five-dimensional probability distribution function (5D-PDF) is being developed for implementation in future data releases. This new 5D-PDF approach allows nearly unambiguous identification of dense dust layers over/near their source regions and therefore enables the study of these layers using a large amount of the CALIPSO data. Lidar ratio (i.e., extinction-to-backscatter ratio) is an intrinsic optical property of aerosols and a key parameter necessary in the lidar signal inversion to retrieve profiles of aerosol extinction and backscatter coefficients, which are two primary products of the CALIPSO level 2 data. This parameter is usually selected in the CALIPSO lidar level 2 data processing based on the aerosol type identified. (Six types of aerosols have been modeled: dust, polluted dust, marine, continental, polluted continental, and smoke.) As more data is being collected by the CALIPSO lidar, validation studies with the CALIPSO measurements are being performed and are now becoming available. For opaque dust layers, the effective lidar ratio (the product of lidar ratio and multiple scattering factor) can be determined easily from integrated attenuated backscatter over the layer top and apparent base. We have performed an extensive analysis based on the first two and a half years (June 2006 - December 2008) of the CALIPSO lidar nighttime measurement data with the 5D-PDF CAD algorithm applied. The effective lidar ratios computed for the opaque dust layers over the North Africa (12N-30N), one of the largest source regions in the world, have a relatively broad distribution, with a mean/median value of 38.5/36.4 sr at 532 nm and 50.3/47.7 sr at 1064 nm. The experimentally determined values are in good agreement with the modeling results for Saharan dust aerosols. Monte-Carlo simulations have also been performed to examine the impact of multiple scattering. The results show that multiple scattering generally has a small impact on the effective lidar (multiple scattering factor at the layer base > 0.9). However, when the dust extinction is > ~ 2/km, the multiple scattering impact can increase significantly. A closer examination of the depolarization ratio profiles in the dense dust layers shows a general agreement with the multiple scattering simulations.

Liu, Z.; Winker, D. M.; Omar, A. H.; Vaughan, M.; Trepte, C. R.; Hu, Y.; Hostetler, C. A.; Sun, W.; Lin, B.

2009-12-01

95

Evaluation of a Raman Lidar for Atmospheric Water Vapour Profiling  

NASA Astrophysics Data System (ADS)

Knowledge of the vertical profile of atmospheric water vapour is important for predicting atmospheric refraction effects for radar and infrared applications. A model is developed to calculate the performance of a vibrational Raman lidar for measuring vertical profiles of atmospheric water vapour, based on the current transmitter and receiver properties of the TNO-FEL backscatter lidar. Calculations are carried out for the four harmonics of the Nd:YAG laser. These calculations show that maximum ranges of approximately 50 m can be obtained for single shot operation during day time with each of the 532, 355 and 266 nm wavelengths (respectively the second, third and fourth harmonics). The maximum range at the fundamental wavelength is only a few meters due to the limited Raman cross section at this wavelength and the limited sensitivity of the detector at the Raman wavelength. By operating the system under night-time conditions, the maximum range increases to about 160 m. The maximum range could further be improved if noise free amplifiers would be available. It is estimated that the maximum range will increase to 360 m if a pre-amplifier is available with an equivalent noise current of 9. 10-13 W/Hz1/2 and a bandwidth of at least 30 MHz. Larger ranges can be obtained by averaging multiple signals. For increasing the maximum range by a factor of 10, the required number of shots is approximately 10,000, which takes about 10 minutes for a 20 Hz lidar system.

Kunz, G. J.; deLeeuw, G.

2002-04-01

96

AMALi - the Airborne Mobile Aerosol Lidar for Arctic research  

Microsoft Academic Search

The Airborne Mobile Aerosol Lidar (AMALi) is an instrument developed at the Alfred Wegener Institute for Polar and Marine Research for reliable operation under the challenging weather conditions at the Earth's polar regions. Since 2003 the AMALi has been successfully deployed for measurements in ground-based installation and zenith- or nadir-pointing airborne configurations during several scientific campaigns in the Arctic. The

I. S. Stachlewska; R. Neuber; A. Lampert; C. Ritter; G. Wehrle

2010-01-01

97

Global estimation of above-cloud aerosols using spaceborne LIDAR  

NASA Astrophysics Data System (ADS)

Estimates of global mean direct climate forcing by absorbing aerosols located above boundary layer clouds are large, uncertain, and almost entirely unconstrained by observations. Spaceborne lidar offers a new opportunity of estimating the aerosols at global scale. Here we use two recently available techniques quantifying the above-cloud aerosols using liquid water clouds as lidar targets from Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) [Chand et al., 2008]. Both methods can quantify aerosols above clouds and are based on their self-calibrating techniques. We used one year of global data between 70N-70S to show that day time calibration constants are different than night time calibrations constants. A clear latitudinal dependence is observed in the calibrations constants in CALIPSO observations. Using these 'self-calibration' constants, aerosol optical depth (AOD) and angstrom exponent (AE) of 'above- cloud' aerosols are quantified. Biomass burning is a major source of fine mode aerosols in different regions of world. For example, it is observed that June is the onset of the biomass burning fires in Southern Africa, peaking in August and September and then slowly decreasing until November, with a corresponding signature in aerosol optical depth. Layers with aerosol optical depth greater than 0.3 are commonly observed up to several thousand kilometers away from Africa over the Atlantic Ocean. The 'above-cloud' AOD as high as 1.5 is observed in the peak months. Despite of large variations is AOD, mean AE of these aerosols is about 1.6, without any systematic variability away from the source region. The results estimating the aerosols above clouds, including other regions at global scale, will be presented in the AGU meeting. Chand, D., T. L. Anderson, R. Wood, R. J. Charlson, Y. Hu, Z. Liu, and M. Vaughan (2008), Quantifying above-cloud aerosol using spaceborne lidar for improved understanding of cloudy-sky direct climate forcing, J. Geophys. Res., 113, D13206, doi:10.1029/2007JD009433.

Chand, D.; Wood, R.; Anderson, T. L.; Satheesh, S. K.; Leahy, L.

2008-12-01

98

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

99

Aerosol Observations by Lidar in the Nocturnal Boundary Layer  

NASA Astrophysics Data System (ADS)

Aerosol observations by lidar in the nocturnal boundary layer (NBL) were performed in Potenza, Southern Italy, from 20 January to 20 February 1997. Measurements during nine winter nights were considered, covering a variety of boundary-layer conditions. The vertical profiles of the aerosol backscattering coefficient at 355 and 723.37 nm were determined through a Klett-modified iterative procedure, assuming the extinction-to-backscattering ratio within the NBL has a constant value. Aerosol average size characteristics were retrieved from almost simultaneous profiles of the aerosol backscattering coefficient at 355 and 723.37 nm, the measurements being consistent with an accumulation mode radius not exceeding 0.4 m. Similar results in terms of aerosol sizes were obtained from measurements of the extinction-to-backscattering ratio profile at 355 nm performed on six nights during the measurement campaign. Backscattering profiles at 723.37 nm were also converted into profiles of aerosol liquid water content.

di Girolamo, Paolo; Ambrico, Paolo Francesco; Amodeo, Aldo; Boselli, Antonella; Pappalardo, Gelsomina; Spinelli, Nicola

1999-07-01

100

The Setup and the Performances of L'Aquila Raman Lidar and Standard PTU and PTO3 Balloon Soundings for Envisat Validation (AOID206)  

Microsoft Academic Search

We report the design and the performances of a Raman lidar for monitoring the tropospheric aerosol backscattering and extinction coefficients, water vapor mixing ratio and cloud liquid water. After describing the system components, along with the c urrent l imitations and o ptions for improvement, we report examples of observations. The PTU and PTO3 balloon soundings are ca rried on

Vincenzo Rizi; Marco Iarlori; Giuseppe Rocci

2003-01-01

101

AMALi - the Airborne Mobile Aerosol Lidar for Arctic research  

NASA Astrophysics Data System (ADS)

The Airborne Mobile Aerosol Lidar (AMALi) is an instrument developed at the Alfred Wegener Institute for Polar and Marine Research for a trouble-free operation under the challenging weather conditions at the Earth's polar regions. Since 2003 the AMALi has been successfully deployed for measurements in the ground-based installation and the zenith- or nadir-aiming airborne configurations during several scientific campaigns in the Arctic. The lidar provides profiles of the total backscatter at two wavelengths, from which aerosol and cloud properties are derived. It measures also the linear depolarization of the backscattered return, allowing for the discrimination of thermodynamic cloud phase and the identification of the presence of non-spherical aerosol particles. This paper presents the capability characteristics and performance of the past and present state of the AMALi system, as well as discusses the ground-based and airborne evaluation schemes applied to invert the data.

Stachlewska, I. S.; Neuber, R.; Lampert, A.; Ritter, C.; Wehrle, G.

2009-09-01

102

Three+two Raman lidar system configuration for space-borne active remote sensing system validation over Athens, Greece, in the frame of the EARLINET-ASOS and ESA-CALIPSO projects  

Microsoft Academic Search

Routine lidar measurements of the aerosol vertical distribution have been performed over Athens, Greece using a multi-wavelength (355-387-407-532-607-1064 nm) Raman lidar system, since 2006 in the frame of the EARLINET-ASOS (2006-2011) project. Additionally, since June 2006, correlative measurements for CALIOP space-borne lidar are performed. The aim of these measurements is to provide validation profiles for the CALIOP instrument in the

Rodanthi Elisabeth Mamouri; Alexandros Papayannis; Vassilis Amiridis; Panayotis Kokkalis; Carlos Pérez; Georgios Tsaknakis

2009-01-01

103

Retrieval of stratospheric aerosol size distributions and integral properties from simulated lidar backscatter measurements.  

PubMed

A new approach for retrieving aerosol properties from extinction spectra is extended to retrieve aerosol properties from lidar backscatter measurements. In this method it is assumed that aerosol properties are expressed as a linear combination of backscatters at three or fewer wavelengths commonly used in lidar measurements. The coefficients in the weighted linear combination are obtained by minimization of the retrieval error averaged for a set of testing size distributions. The formulas can be used easily by investigators to retrieve aerosol properties from lidar backscatter measurements such as the Lidar In-Space Technology Experiment and Pathfinder Instruments for Clouds and Aerosols Spaceborne Observations. PMID:18354540

Yue, G K

2000-10-20

104

Research on stimulated Raman scattering with applications to atmospheric lidar  

NASA Astrophysics Data System (ADS)

Research has been conducted on stimulated Raman scattering (SRS) to extend conventional lasers into the infrared where lidar systems can make important contributions to observations of the atmosphere. An efficient 'Raman shifted' dye laser system was used to generate tunable and narrow band radiation at 760 and 940 nm for differential absorption lidar applications. The requisite tunability and spectral purity of the output is derived from the dye laser input by controlling the Raman cell at pressure below 14 atm. The converted radiation is optimized for different pump focusing geometries. Energy conversion efficiencies of 45 percent and 37 percent at 765 and 940 nm, respectively, were obtained. Optical depth measurements and calculations were made at the centers of 25 lines in the P branch of the oxygen A-band in air. The data and theoretical calculations agree, indicating a high spectral purity of the light source. High resolution parameters of water vapor at 940 nm were obtained using this narrow linewidth Raman-shifted dye laser in conjunction with a multi-pass optical absorption call. Optical strengths and Lorentz widths were reduced from the data using a Voigt line profile to numerically correct for finite laser linewidth. Some lines are compared with prior measurements by Giver et al. that used a wholly different method. Some lines, which were not covered in Giver's experiments, were compared with Hitran database. The simultaneous generation of several Stokes orders was investigated in H2, D2, and CH4, for the purpose of multiple wavelength lidar. The study was focused on the redistribution of the pump energy into the different SRS components. Optimal experimental conditions were investigated and calculated. Eye-safe radiation at 1.54 micrometers was generated for lidar applications, by Raman shifting Nd:YAG laser light (1.06 micrometers) in methane. To increase conversion efficiency, a novel self-seeding oscillator and amplifier system was designed and used. Backward first Stokes radiation was separated and used as seed by being refocussed into the Raman cell and amplified by the rest of the pump pulse. A maximum conversion efficiency of 18 percent was obtained.

Chu, Zhiping

1991-02-01

105

Tropical stratospheric aerosol layer from CALIPSO lidar observations  

NASA Astrophysics Data System (ADS)

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 scattering between 30 and 34 km the current calibration leads to an average underestimation of the scattering ratio by 6% because of the significant amount of aerosols up to 35 km altitude in the tropics, in contrast to midlatitudes. A better result is obtained by adjusting the calibration to higher altitudes, 36-39 km, where past Stratospheric Aerosol and Gas Experiment (SAGE) II extinction measurements showed an almost complete absence of aerosols. After recalibration the tropical stratospheric aerosol picture provided by CALIOP during the first 2 years of the mission reveals significant changes in the aerosol concentration associated with different transport processes. In the stratosphere the slow ascent of several volcanic layers and their meridional transport toward the subtropics are very consistent with the Brewer-Dobson circulation. The near-zero vertical velocity observed around 20 km during the Northern Hemisphere (NH) summer is in good agreement with radiative heating calculation. In the Tropical Tropopause Layer (TTL), weak depolarizing particles are observed during land convective periods, particularly intense over South Asia during the monsoon season. Finally, seasonal fast occurrence of apparent clean air in the TTL during the NH winter requires more investigations to understand its origin.

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

2009-02-01

106

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.

2011-11-01

107

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

108

Inter-comparison of lidar and ceilometer retrievals for aerosol and Planetary Boundary Layer profiling over Athens, Greece  

NASA Astrophysics Data System (ADS)

This study presents an inter-comparison of two active remote sensors (lidar and ceilometer) to determine the mixing layer height and structure of the Planetary Boundary Layer (PBL) and to retrieve tropospheric aerosol vertical profiles over Athens, Greece. This inter-comparison was performed under various strongly different aerosol loads/types (urban air pollution, biomass burning and Saharan dust event), implementing two different lidar systems (one portable Raymetrics S.A. lidar system running at 355 nm and one multi-wavelength Raman lidar system running at 355 nm, 532 nm and 1064 nm) and one CL31 Vaisala S.A. ceilometer (running at 910 nm). Spectral conversions of the ceilometer's data were performed using the Ångström exponent estimated by ultraviolet multi-filter radiometer (UV-MFR) measurements. The inter-comparison was based on two parameters: the mixing layer height determined by the presence of the suspended aerosols and the attenuated backscatter coefficient. Additionally, radiosonde data were used to derive the PBL height. In general, a good agreement was found between the ceilometer and the lidar techniques in both inter-compared parameters in the height range from 500 m to 5000 m, while the limitations of each instrument are also examined.

Tsaknakis, G.; Papayannis, A.; Kokkalis, P.; Amiridis, V.; Kambezidis, H. D.; Mamouri, R. E.; Georgoussis, G.; Avdikos, G.

2011-06-01

109

Observations of Evaporation with a New-Generation Raman Lidar  

NASA Astrophysics Data System (ADS)

A new atmospheric boundary layer Raman lidar has been designed and built at EPFL. Temperature and humidity can be measured out to 500 m at 1 m spatial resolution, 1 s temporal resolution. A unique multi-telescope design along with 3 nanoseconds 100 Hz pulsed laser operating at 266 nm (in the solar blind region) with ozone correction allows for nearly constant signal to noise, daytime operation and measurement scales of interest in micrometeorology. In this presentation we will detail the underlying principle of this lidar and present new observations of water and temperature microstructure of the lower atmosphere over complex terrain. First calibration results, field observations over a vineyard and time series of vertical temperature and humidity profiles will be presented.

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

2007-12-01

110

Atmospheric measurements using a scanning, solar-blind Raman Lidar  

NASA Astrophysics Data System (ADS)

The study of the water cycle by Lidar has many applications. Because micro-scale structures can be identified by their water content, the technique offers new opportunities to visualize and study the phenomena. There are applications to many practical problems in agricultural and water management as well as at waste storage sites. Conventional point sensors are limited and are inappropriate for use in complex terrain or varied vegetation and cannot be extrapolated over even modest ranges. To this end, techniques must be developed to measure the variables associated with evapotranspirative processes over large areas and varied surface conditions. A scanning water-Raman Lidar is an ideal tool for this task - it can measure the water vapor concentration rapidly with high spatial resolution without influencing the measurements by the presence of the sensor.

Eichinger, W. E.; Cooper, D. I.; Holtkamp, D. B.; Karl, R. R., Jr.; Quick, C. R.; Tiee, J. J.

111

Raman lidar spectrum reconstruction of methane and deuterium containing methanes mixture  

NASA Astrophysics Data System (ADS)

The lidar Raman spectrum of methane molecules CH4,CH3D and CH2D2 transformation at copper vapor laser radiation wavelengths and ranging distances from 0.1 up to 6.0 km can be used for accuracy concentration measurements and lidar potential predictions. The studied gaseous mixture of different contents Raman spectra computer reconstruction have been made on the basis of back scattered vibrational Raman lidar equation computer simulation for these molecules with copper vapor laser radiation wavelengths and Raman bands half-width which were by shock theory for according experimental conditions in the free atmosphere.

Shemanin, Valery G.; Grishina, Eleonora N.; Voronina, Elina I.

2003-06-01

112

AMALi - the Airborne Mobile Aerosol Lidar for Arctic research  

Microsoft Academic Search

The Airborne Mobile Aerosol Lidar (AMALi) is an instrument developed at the Alfred Wegener Institute for Polar and Marine Research for a trouble-free operation under the challenging weather conditions at the Earth's polar regions. Since 2003 the AMALi has been successfully deployed for measurements in the ground-based installation and the zenith- or nadir-aiming airborne configurations during several scientific campaigns in

I. S. Stachlewska; R. Neuber; A. Lampert; C. Ritter; G. Wehrle

2009-01-01

113

Aglite lidar: a portable elastic lidar system for investigating aerosol and wind motions at or around agricultural production facilities  

NASA Astrophysics Data System (ADS)

The Aglite Lidar is a portable scanning lidar that can be quickly deployed at agricultural and other air quality study sites. The purpose of Aglite is to map the concentration of PM10 and PM2.5 in aerosol plumes from agricultural and other sources. Aglite uses a high-repetition rate low-pulse energy 3-wavelength YAG laser with photon-counting detection together with a steerable pointing mirror to measure aerosol concentration with high spatial and temporal resolution. Aglite has been used in field campaigns in Iowa, Utah and California. The instrument is described, and performance and lidar sensitivity data are presented. The value of the lidar in aerosol plume mapping is demonstrated, as is the ability to extract wind-speed information from the lidar data.

Marchant, Christian C.; Wilkerson, Thomas; Bingham, Gail E.; Zavyalov, Vladimir V.; Andersen, Jan M.; Wright, Cordell B.; Cornelsen, Scott S.; Martin, Randal S.; Silva, Philip J.; Hatfield, Jerry L.

2009-02-01

114

Error analysis of Raman differential absorption lidar ozone measurements in ice clouds.  

PubMed

A formalism for the error treatment of lidar ozone measurements with the Raman differential absorption lidar technique is presented. In the presence of clouds wavelength-dependent multiple scattering and cloud-particle extinction are the main sources of systematic errors in ozone measurements and necessitate a correction of the measured ozone profiles. Model calculations are performed to describe the influence of cirrus and polar stratospheric clouds on the ozone. It is found that it is sufficient to account for cloud-particle scattering and Rayleigh scattering in and above the cloud; boundary-layer aerosols and the atmospheric column below the cloud can be neglected for the ozone correction. Furthermore, if the extinction coefficient of the cloud is ?0.1 km(-1), the effect in the cloud is proportional to the effective particle extinction and to a particle correction function determined in the limit of negligible molecular scattering. The particle correction function depends on the scattering behavior of the cloud particles, the cloud geometric structure, and the lidar system parameters. Because of the differential extinction of light that has undergone one or more small-angle scattering processes within the cloud, the cloud effect on ozone extends to altitudes above the cloud. The various influencing parameters imply that the particle-related ozone correction has to be calculated for each individual measurement. Examples of ozone measurements in cirrus clouds are discussed. PMID:18354611

Reichardt, J

2000-11-20

115

Water vapour profiling in cloudy conditions integrating Raman lidar and passive microwave observations  

NASA Astrophysics Data System (ADS)

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

Madonna, Fabio; Boselli, Antonella; Amodeo, Aldo; Cornacchia, Carmela; D'Amico, Giuseppe; Giunta, Aldo; Mona, Lucia; Pappalardo, Gelsomina

2010-10-01

116

Use of In Situ Data to Test a Raman Lidar-Based Cloud Condensation Nuclei Remote Sensing Method  

SciTech Connect

A method of retrieving vertical profiles of cloud condensation nuclei (CCN) concentration from surface measurements is proposed. Surface measurements of the CCN concentration are scaled by the ratio of the backscatter (or extinction) vertical profile to the backscatter (or extinction) at or near the surface. The backscatter (or extinction) profile is measured by Raman lidar, and is corrected to dry conditions using the vertical profile of relative humidity (also measured by Raman lidar) and surface measurements of the dependence of backscatter (or extinction) on relative humidity. The method assumes the surface aerosol size distribution and composition are representative of the vertical column. Aircraft measurements of aerosol size distribution are used to test the dependence of the retrieval on the uniformity of aerosol size distribution. The retrieval is found to be robust for supersaturations less than 0.02%, but breaks down at higher supersaturations if the vertical profile of aerosol size distribution differs markedly from the distribution at the surface. Such conditions can be detected from the extinction/backscatter ratio.

Ghan, Steven J.; Collins, Donald R.

2004-02-01

117

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

118

Airborne Lidar Stratospheric Ozone and Aerosol Investigations.  

National Technical Information Service (NTIS)

The objectives are to study the distribution of ozone (O3) and aerosols across the polar regions during the winter and spring periods and to relate these observations to chemical and dynamical processes that can contribute to the chemical perturbation of ...

E. V. Browell

1990-01-01

119

Pure rotational-Raman channels of the Esrange lidar for temperature and particle extinction measurements in the troposphere and lower stratosphere  

NASA Astrophysics Data System (ADS)

The Department of Meteorology at Stockholm University operates the Esrange Rayleigh/Raman lidar at Esrange (68° N, 21° E) near the Swedish city of Kiruna. This paper describes the design and first measurements of the new pure rotational-Raman channel of the Esrange lidar. The Esrange lidar uses a pulsed Nd:YAG solid-state laser operating at 532 nm as light source with a repetition rate of 20 Hz and a pulse energy of 350 mJ. The minimum vertical resolution is 150 m and the integration time for one profile is 5000 shots. The newly implemented channel allows for measurements of atmospheric temperature at altitudes below 35 km and is currently optimized for temperature measurements between 180 and 200 K. This corresponds to conditions in the lower Arctic stratosphere during winter. In addition to the temperature measurements, the aerosol extinction coefficient and the aerosol backscatter coefficient at 532 nm can be measured independently. Our filter-based design minimizes the systematic error in the obtained temperature profile to less than 0.51 K. By combining rotational-Raman measurements (5-35 km height) and the integration technique (30-80 km height), the Esrange lidar is now capable of measuring atmospheric temperature profiles from the upper troposphere up to the mesosphere. With the improved setup, the system can be used to validate current lidar-based polar stratospheric cloud classification schemes. The new capability of the instrument measuring temperature and aerosol extinction furthermore enables studies of the thermal structure and variability of the upper troposphere/lower stratosphere. Although several lidars are operated at polar latitudes, there are few instruments that are capable of measuring temperature profiles in the troposphere, stratosphere, and mesosphere, as well as aerosols extinction in the troposphere and lower stratosphere with daylight capability.

Achtert, P.; Khaplanov, M.; Khosrawi, F.; Gumbel, J.

2013-01-01

120

Airborne High Spectral Resolution Lidar Aerosol Measurements during ARCTAS  

NASA Astrophysics Data System (ADS)

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 over Alaska and the Arctic Ocean during April and 14 science flights over northwestern Canada during June and July. The HSRL measurements indicated that a much higher fraction (>40-50%) of aerosol optical thickness was located in elevated layers during both spring and summer portions of ARCTAS than was measured by HSRL during previous campaigns at lower latitudes. The NASA P-3 and DC-8, NOAA WP-3, and the Canadian Convair-580 research aircraft (which operated under contract to the DOE) often collected coincident data within the HSRL “curtains” thereby facilitating extensive intercomparisons and combined analyses. Intercomparisons of aerosol extinction coefficients measured by the HSRL, an in situ Cavity-Ring Down (CRD) sensor on the NOAA WP-3B, and derived from in situ measurements of scattering and absorption on NASA P 3B and Convair-580 are presented. Aerosol intensive parameters derived from HSRL data are used to infer specific aerosol types and mixtures of those types. An aerosol type inferred to be a mixture of burning smoke and urban pollution was found to provide the largest contribution to aerosol optical thickness during both the spring and summer ARCTAS campaigns. HSRL measurements of aerosol intensive parameters, and the aerosol types inferred from these measurements, indicate significant vertical variability in these aerosol properties. The relationships between the aerosol types inferred from the HSRL data and the in situ measurements of aerosol size and composition collected on the other aircraft are discussed. This presentation will also describe correlations between HSRL profile measurements of backscatter Angstrom exponent and coincident in situ measurements of aerosol submicrometer fraction. An aerosol index is defined here as the product of aerosol extinction and the backscatter Angstrom exponent; correlations of this index with in situ measurements of Cloud Condensation Nuclei (CCN) concentration will also be discussed.

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

2009-12-01

121

Remote Detection and Identification of CO2 Dissolved in Water Using a Raman Lidar System  

NASA Astrophysics Data System (ADS)

We demonstrated the first range-resolved detection and identification of CO2 dissolved in water by Raman lidar. A frequency doubled Q-switched neodymium-doped yttrium aluminum garnet (Nd:YAG) laser (532 nm) is used as the lidar light source, and the Raman signals at ˜1273 and ˜1380 cm-1 from CO2 dissolved in water were detected. In lidar application, CO2 dissolved in water was identified in glass bottles 20 m away by using the CO2 Raman band at ˜1380 cm-1.

Somekawa, Toshihiro; Tani, Atsushi; Fujita, Masayuki

2011-11-01

122

Estimation and discrimination of aerosols using multiple wavelength LWIR lidar  

NASA Astrophysics Data System (ADS)

This paper presents an overview of recent work by the Edgewood Chemical Biological Center (ECBC) in algorithm development for parameter estimation and classification of localized atmospheric aerosols using data from rapidly tuned multiple-wavelength range-resolved LWIR lidar. The motivation for this work is the need to detect, locate, and discriminate biological threat aerosols in the atmosphere from interferent materials such as dust and smoke at safe standoff ranges using time-series data collected at a discrete set of CO2 laser wavelengths. The goals of the processing are to provide real-time aerosol detection, localization, and discrimination. Earlier work by the authors has produced an efficient Kalman filter-based algorithm for estimating the range-dependent aerosol concentration and wavelength-dependent backscatter signatures. The latter estimates are used as feature vectors for training support vector machines classifiers for performing the discrimination. Several years of field testing under the Joint Biological Standoff Detection System program at Dugway Proving Ground, UT, Eglin Air Force Base, FL, and other locations have produced data and backscatter estimates from a broad range of biological and interferent aerosol materials for the classifier development. The results of this work are summarized in our presentation.

Warren, Russell E.; Vanderbeek, Richard G.; Ahl, Jeffrey L.

2010-04-01

123

Characterization and First Measurements of the new CANDAC Raman Lidar (CRL)  

NASA Astrophysics Data System (ADS)

The Canadian Network for the Detection of Atmospheric Change (CANDAC), a collaboration between several universities and government organizations, has established a suite of instruments in Eureka, Nunavut, Canada (79°59'N, 85°56'W). As part of this program, Dalhousie University's Rayleigh-Mie- Raman lidar has been installed at the sea-level atmospheric laboratory, (ØPAL). Designed for the remote profiling aerosol content, temperature, and water vapour, the lidar will provide a detailed dataset for further investigation of atmospheric thermodynamics, radiative transfer and cloud micro-physics. The ability to retrieve signal from a wide range of altitudes is important to make the measurements as extensive as possible. This system includes a number of feathers designed to expand this range, including the dynamic movement of the field stop. The approaches used and their comprehensive characterization is presented. Updated descriptions of instrument specifications and remote operations are presented as well as a detailed characterization of the seven channels. Of particular interest are the temperature and H2O vapour mixing ratios derived from these measurements. Calibration and preliminary results are shown, and the confidence in the retrievals is discussed. The ability to retrieve signal from a wide range of altitudes is important to make the measurements as extensive as possible.

Doyle, J.; Nott, G.; Duck, T.

2008-12-01

124

Airborne lidar measurements of El Chichon stratospheric aerosols  

NASA Astrophysics Data System (ADS)

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.

1985-10-01

125

Optimizing the Spectral Parameters of a Lidar Receiver for Rotational Raman Temperature Measurements  

Microsoft Academic Search

For the GKSS Raman lidar, a combined system for the measurement of optical particle properties, ozone, and mois- ture, a polychromator for temperature measurements with the rotational Raman technique was developed. Since early 1998, this instrument has proved its reliability and high performance in three field campaigns. Temperature data could be taken even in the presence of clouds and up

ANDREAS BEHRENDT; CLAUS WEITKAMP

126

Macrophysical properties of tropical cirrus clouds from the CALIPSO satellite and from ground-based micropulse and Raman lidars  

NASA Astrophysics Data System (ADS)

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 Infrared 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 cycle is significantly different from zero only below about 11 km; where it is of opposite sign (i.e., more clouds during the daytime). For cirrus geometrical thickness, the MPL and CALIPSO observations agree well and both data sets have significantly 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 significant improvement the RL provides (compared to the MPL) in the ARM program's ability to observe tropical cirrus clouds and will help improve our understanding of these clouds. The RL also provides a valuable ground-based lidar data set for the evaluation of CALIPSO observations.

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

2013-08-01

127

Two-wavelength lidar measurement of Cloud-aerosol optical properties  

NASA Astrophysics Data System (ADS)

Based on unstability of inversion algorithms of the lidar equation caused by molecular scattering, a new algorithm to derive both the aerosol extinction to backscatter ratio and the extinction coefficient profile is proposed in this paper. As shown in numerical experiments, in case of a ground-based lidar, the error in the aerosol optical depth solution can be less than 10%, and the error of < 6.7 in the aerosol extinction to backscatter ratio can be obtained if the error in the lidar constant is < 6%; and in the case of a spaceborne lidar, the present method can be used to de-termine the lidar constant at a short wavelength with an accuracy of being better than 1%.

Qiu, Jinhuan

1995-05-01

128

Comparative study of aerosols observed by YAG lidar and airborne detectors  

NASA Astrophysics Data System (ADS)

The causal relationships of very large (tropical) volcanic eruptions and El Nino Southern Oscillations (ENSO) based on the unequal atmospheric heating by aerosols observed by lidar and airborne detectors are discussed.

Hirono, M.; Fujiwara, M.; Shibata, T.

1985-12-01

129

Mie Scattering Lidar Observation of Aerosol Vertical Profiles in Jakarta, Indonesia  

Microsoft Academic Search

Vertical profiles of aerosols were observed in Jakarta, Indonesia, with a Mie scattering lidar network system consisting of three lidars located in the coastal, central, and inland areas. The structure of the planetary boundary layer was observed for one week during the September to October 1997 dry season. Radiosonde observation was performed in the same period in Jakarta. The diurnal

Mego Pinandito; Imam Rosananto; Santoso Sugondo; Siti Asiati

2000-01-01

130

Lidar estimation of tropospheric aerosol extinction, surface area and volume: Maritime and desert-dust cases  

Microsoft Academic Search

A numerical model, based on a Monte Carlo approach, is presented to determine functional relationships linking backscatter and other important properties as extinction, surface area, and volume of tropospheric aerosols. If existing, such relationships allow for a direct estimate of such properties by means of a single-wavelength lidar measurement. To be employed in a lidar inversion procedure, the extinction to

Francesca Barnaba; Gian Paolo Gobbi

2001-01-01

131

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

132

The May/June 2008 Saharan dust event over Munich: Intensive aerosol parameters from lidar measurements  

NASA Astrophysics Data System (ADS)

At the end of May 2008 one of the strongest Saharan dust outbreaks ever reached Central Europe. This event gave us the opportunity to extend our series of studies on Saharan dust characterization, which includes measurements near the source (SAMUM-1, Morocco) and in the regime of mid range transport (SAMUM-2, Cape Verde). The optical properties of the aerosol particles as a function of time and height are derived from data of the two Raman depolarization-lidar systems MULIS and POLIS at Munich and Maisach (Germany), respectively. Measurements include the extensive properties of the particles, backscatter coefficient ?p and extinction coefficient ?p, and the intensive particle properties, linear depolarization ratio ?p and lidar ratio Sp. All quantities are derived at two wavelengths, ? = 355 nm and ? = 532 nm. The focus of the study is on the intensive properties, for which we found on average ?p = 0.30 at 355 nm and ?p = 0.34 at 532 nm. The systematic errors were typically larger than the ?p-difference at the two wavelengths. With respect to the lidar ratio, we found Sp = 59 sr for both wavelengths, with an uncertainty range between ±4 sr and ±10 sr. These values are quite similar to the results from the SAMUM campaigns. Thus, our results suggest that the intensive optical properties of Saharan dust do not change significantly if the transport time is less than one week. However, more case studies in the far-range regime are required to scrutinize this statement. To further refine conclusions with respect to the wavelength dependence of ?p a further reduction of the errors is desired.

Wiegner, M.; Groß, S.; Freudenthaler, V.; Schnell, F.; Gasteiger, J.

2011-12-01

133

Remote daytime measurements of tropospheric temperature profiles with a rotational Raman lidar.  

PubMed

Tropospheric temperature profiles have been measured at daytime with a rotational Raman lidar. The lidar operates in the solar-blind spectral region with KrF laser radiation that is Raman shifted in hydrogen to 276.787 nm. This wavelength corresponds to the resonance absorption of a thallium atomic-vapor f ilter that is used to suppress the large elastic-backscatter signal. The rotational Raman signal is analyzed with an echelle grating spectrometer that separates spectral regions with different temperature sensitivities in both the Stokes and the anti-Stokes Raman spectra. Simultaneously, profiles of water vapor and ozone can be determined by means of vibrational Raman backscattering. PMID:19876332

Zeyn, J; Lahmann, W; Weitkamp, C

1996-08-15

134

Raman lidar characterization of the meteorological, electromagnetic, and electro-optical environment  

NASA Astrophysics Data System (ADS)

Raman lidar has provided a remarkable tool for characterizing the various properties of the lower atmosphere. The research of the Penn State University Lidar Laboratory is focused on development of Raman lidar techniques and research using five Raman lidar instruments prepared since the mid-1970's. The LAPS instrument was demonstrated in 1996 as the first prototype for an operational shipboard lidar sensor. It is the most advanced lidar instrument developed to date for profiling properties of the lower atmosphere. The LAPS sensor measures profiles with eight data channels to determine several atmospheric properties simultaneously. The single most important property for understanding the meteorological state in the lower atmosphere is the water vapor profile. The specific humidity and temperature profiles are measured directly using the vibrational and rotational Raman scattered signals. The electromagnetic parameter of most interest is the gradient in the refractive index profile, because of the influence it has on RF-propagation of radar and radio communications signals. The electro-optical parameter of most interest is the optical extinction profile at various wavelengths, because optical propagation affects aircraft operations, visual aesthetics, and optical sensor performance. Profiles of water vapor, temperature and multiwavelength optical extinction are measured simultaneously to describe the meteorological, electromagnetic, electro-optical and air quality environmental conditions. Measurements are key in forecasting atmospheric conditions and are of major importance because of their influence on the performance of various systems. Current techniques and capabilities are described in this paper, and examples are used to indicate how well the Raman lidar performs in characterizing the atmosphere.

Philbrick, C. Russell

2005-08-01

135

Refinement of calipso aerosol retrieval models through analysis of airborne high spectral resolution lidar data  

NASA Astrophysics Data System (ADS)

The deepening of scientific understanding of atmospheric aerosols figures substantially into stated goals for climate change research and a variety of internationally collaborative earth observation missions. One such mission is the joint NASA/Centre National d'Etudes Spatiales (CNES) Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) mission, whose primary instrument is the Cloud-Aerosol LIdar with Orthogonal Polarization (CALIOP), a spaceborne two-wavelength, elastic-scatter lidar, which has been making continuous, global observations of atmospheric aerosols and clouds since June of 2006, shortly after its launch in April of the same year. The work presented in this dissertation consists of the development of an aerosol retrieval strategy to improve aerosol retrievals from lidar data from the CALIPSO mission, as well as a comprehensive formulation of accompanying aerosol models based on a thorough analysis of data from an airborne High Spectral Resolution Lidar (HSRL) instrument. The retrieval methodology, known as the Constrained Ratio Aerosol Model-fit (CRAM) technique, is a means of exploiting the available dual-wavelength information from CALIOP to constrain the possible solutions to the problem of aerosol retrieval from elastic-scatter lidar so as to be consistent with theoretically or empirically known aerosol models. Constraints applied via CRAM are manifested in spectral ratios of scattering parameters corresponding to observationally-based aerosol models. Consequently, accurate and representative models incorporating various spectral scattering parameters are instrumental to the successful implementation of a methodology like CRAM. The aerosol models arising from this work are derived from measurements made by the NASA Langley Research Center (LaRC) airborne HSRL instrument, which has the capability to measure both aerosol scattering parameters (i.e., backscatter and extinction) independently at 532 nm. The instrument also incorporates an elastic-scatter channel at 1064 nm, facilitating the incorporation of dual-wavelength information by way of particular constraints. The intent in developing these new models is to furnish as satisfactory a basis as possible for retrieval techniques such as CRAM, whose approach to the problem of aerosol retrieval attempts to make optimal use of the available spectral information from multi-wavelength lidar, thus providing a framework for improving aerosol retrievals from CALIPSO and furthering the scientific goals related to atmospheric aerosols.

McPherson, Christopher J.

136

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

137

Vertical profiles of microphysical particle properties derived from inversion with two-dimensional regularization of multiwavelength Raman lidar data: experiment.  

PubMed

Inversion with two-dimensional (2-D) regularization is a new methodology that can be used for the retrieval of profiles of microphysical properties, e.g., effective radius and complex refractive index of atmospheric particles from complete (or sections) of profiles of optical particle properties. The optical profiles are acquired with multiwavelength Raman lidar. Previous simulations with synthetic data have shown advantages in terms of retrieval accuracy compared to our so-called classical one-dimensional (1-D) regularization, which is a method mostly used in the European Aerosol Research Lidar Network (EARLINET). The 1-D regularization suffers from flaws such as retrieval accuracy, speed, and ability for error analysis. In this contribution, we test for the first time the performance of the new 2-D regularization algorithm on the basis of experimental data. We measured with lidar an aged biomass-burning plume over West/Central Europe. For comparison, we use particle in situ data taken in the smoke plume during research aircraft flights upwind of the lidar. We find good agreement for effective radius and volume, surface-area, and number concentrations. The retrieved complex refractive index on average is lower than what we find from the in situ observations. Accordingly, the single-scattering albedo that we obtain from the inversion is higher than what we obtain from the aircraft data. In view of the difficult measurement situation, i.e., the large spatial and temporal distances between aircraft and lidar measurements, this test of our new inversion methodology is satisfactory. PMID:21556108

Müller, Detlef; Kolgotin, Alexei; Mattis, Ina; Petzold, Andreas; Stohl, Andreas

2011-05-10

138

Observation of Lower-Atmospheric Moisture Structure and its Evolution Using a Raman Lidar.  

NASA Astrophysics Data System (ADS)

Observations of the water-vapor mixing ratio in the lower atmosphere and its temporal evolution have been made with a Raman lidar. Comparison with an independent radiosonde measurement indicated excellent agreement. The moisture structure, observed up to an altitude of 5 km and over an 80-min period during the early morning of 30 April 1985 (the present lidar is limited to night operation), showed temporal variations of several atmospheric features which could not be resolved by balloon soundings. Application of the lidar should provide the opportunity to study details of atmospheric moisture, its structure, and its evolution in a manner never before realized.

Melfi, S. H.; Whiteman, D.

1985-10-01

139

Two-wavelength lidar characterization of atmospheric aerosol fields at low altitudes over heterogeneous terrain  

NASA Astrophysics Data System (ADS)

The possibilities for applying multiwavelength elastic lidar probing of the atmosphere to help monitor air-quality over large industrial and densely populated areas, based predominantly on the use and analysis of commonly obtainable backscatter-related lidar quantities, are examined. Presented are two-wavelength (1064/532 nm) lidar observations on the spatial distribution, structure, composition, and temporal evolution of close-to-surface atmospheric aerosol fields over heterogeneous orographic areas (adjacent city, plain, and mountain) near Sofia, Bulgaria. Selected winter-time evening lidar measurements are described. Range profiles, histograms, and evolutional range-time diagrams of the aerosol backscatter coefficients, range-corrected lidar signals, normalized standard deviations, and backscatter-related Ångström exponents (BAE) are analyzed. Near-perfect correlation between the aerosol density distribution and orographic differentiation of the underlying terrain is established, finding expression in a sustained horizontal stratification of the probed atmospheric domains. Distinctive features in the spatial distribution and temporal evolution of both the fine- and coarse aerosol fractions are revealed in correlation with terrain's orography. Zonal aerosol particle size distributions are qualitatively characterized by using an approach based on BAE occurrence frequency distribution analysis. Assumptions are made about the aerosol particle type, origin, and dominating size as connected (by transport-modeling data) to local pollution sources. Specifics and patterns of temporal dynamics of the fine- and coarse aerosol fraction density distributions and movements, revealed by using statistical analysis of lidar data, are discussed. The obtained results prove the capability of the used two-wavelength lidar approach to perform fast-, reliable, and self-consistent characterization of important optical-, micro-physical-, and dynamical properties of atmospheric aerosols over broad areas with high temporal- and range resolution.

Peshev, Zahary Y.; Dreischuh, Tanja N.; Toncheva, Eleonora N.; Stoyanov, Dimitar V.

2012-01-01

140

Investigating cloud radar sensitivity to optically thin cirrus using collocated Raman lidar observations  

NASA Astrophysics Data System (ADS)

The sensitivity of the millimeter cloud radar (MMCR) to optically thin single-layer cirrus at the Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) site is investigated using collocated Raman lidar observations. The sensitivity is characterized in terms of cloud optical depth (OD) and infrared (IR) radiative flux using over three years of coincident Raman lidar and MMCR observations. For cases when the Raman lidar is not fully attenuated (OD < 2.0) the MMCR detects approximately 70% of the total cloud OD with the majority of missed cloud OD occurring near cloud top. If only MMCR observations are used for computing cloudy top-of-the-atmosphere (TOA) IR flux, the missed cloud OD results in TOA flux biases from 0 to over 100 W/m2; however, the most frequently occurring bias is approximately 16 W/m2. This result highlights the importance of combining Raman lidar, or other sensitive cloud lidars that are able to measure cloud extinction directly, with the MMCR in order to accurately characterize the cloud radiative forcing for thin cirrus cases.

Borg, Lori A.; Holz, Robert E.; Turner, David D.

2011-03-01

141

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

142

Ultraviolet mini-Raman lidar for stand-off, in situ identification of chemical surface contaminants  

SciTech Connect

The Mini-Raman Lidar System (MRLS) is a portable chemical sensor that combines the spectral fingerprinting of Raman spectroscopy with the principles of solar-blind ultraviolet lidar for short-range, noncontact detection and identification of unknown substances on surfaces. The MRLS has the potential to detect contaminant films several microns thick at distances of meters and bulk quantities of substances at distances of tens of meters. The signal acquisition time is less than 1 min. The device has application to those involved in emergency response, environmental remediation, and military reconnaissance who respond initially at the site of a chemical spill or attack. (c) 2000 American Institute of Physics.

Ray, Mark D. [Brookhaven National Laboratory, Upton, New York 11973 (United States); Sedlacek, Arthur J. [Brookhaven National Laboratory, Upton, New York 11973 (United States); Wu, Ming [Brookhaven National Laboratory, Upton, New York 11973 (United States)

2000-09-01

143

Comparison of ambient aerosol extinction coefficients obtained from in-situ, MAX-DOAS and LIDAR measurements at Cabauw  

NASA Astrophysics Data System (ADS)

In the field, aerosol in-situ measurements are often performed under dry conditions (relative humidity RH<30-40%). Since ambient aerosol particles experience hygroscopic growth at enhanced RH, also their microphysical and optical properties - especially the aerosol light scattering - are strongly dependent on RH. The knowledge of this RH effect is of crucial importance for climate forcing calculations or for the comparison of remote sensing with in-situ measurements. Here, we will present results from a four-month campaign which took place in summer 2009 in Cabauw, The Netherlands. The aerosol scattering coefficient ?sp(?) was measured dry and at various, predefined RH conditions between 20 and 95% with a humidified nephelometer. The scattering enhancement factor f(RH,?) is the key parameter to describe the effect of RH on ?sp(?) and is defined as ?sp(RH,?) measured at a certain RH divided by the dry ?sp(dry,?). The measurement of f(RH,?) together with the dry absorption measurement (assumed not to change with RH) allows the determination of the actual extinction coefficient ?ep(RH,?) at ambient RH. In addition, a wide range of other aerosol properties were measured in parallel. The measurements were used to characterize the effects of RH on the aerosol optical properties. A closure study showed the consistency of the aerosol in-situ measurements. Due to the large variability of air mass origin (and thus aerosol composition) a simple parameterization of f(RH,?) could not be established. If f(RH,?) needs to be predicted, the chemical composition and size distribution needs to be known. Measurements of four MAX-DOAS (multi-axis differential optical absorption spectroscopy) instruments were used to retrieve vertical profiles of ?ep(?). The values of the lowest layer were compared to the in-situ values after conversion of the latter to ambient RH. The comparison showed a good correlation of R2=0.62-0.78, but the extinction coefficients were a factor of 1.5-3.4 larger than the in-situ values. Best agreement is achieved for a few cases characterized by low aerosol optical depths and low planetary boundary layer heights. Differences showed to be dependent on the applied MAX-DOAS retrieval algorithm. The comparison of the in-situ data to a Raman lidar (light detection and ranging) showed a good correlation and higher values measured by the lidar (R2=0.79, slope of 1.81) if the Raman retrieved profile was used to extrapolate the directly measured extinction coefficient to the ground. The comparison improved if only nighttime measurements were used in the comparison (R2=0.93, slope of 1.19).

Zieger, P.; Weingartner, E.; Henzing, J.; Moerman, M.; de Leeuw, G.; Mikkilä, J.; Ehn, M.; Petäjä, T.; Clémer, K.; van Roozendael, M.; Yilmaz, S.; Frieß, U.; Irie, H.; Wagner, T.; Shaiganfar, R.; Beirle, S.; Apituley, A.; Wilson, K.; Baltensperger, U.

2010-12-01

144

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

145

Measurements of aerosol vertical profiles and optical properties during INDOEX 1999 using micropulse lidars  

Microsoft Academic Search

Micropulse lidar (MPL) systems were used to measure aerosol properties during the Indian Ocean Experiment (INDOEX) 1999 field phase. Measurements were made from two platforms: the NOAA ship R\\/V Ronald H. Brown, and the Kaashidhoo Climate Observatory (KCO) in the Maldives. Sun photometers were used to provide aerosol optical depths (AOD) needed to calibrate the MPL. This study focuses on

Ellsworth J. Welton; Kenneth J. Voss; Patricia K. Quinn; Piotr J. Flatau; Krzysztof Markowicz; James R. Campbell; James D. Spinhirne; Howard R. Gordon; James E. Johnson

2002-01-01

146

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

National Technical Information Service (NTIS)

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 o...

V. Srivastava A. D. Clarke M. A. Jarzembski J. Rothermel

1997-01-01

147

Multiwavelength lidar measurements of stratospheric aerosols above Spitsbergen during winter 1992\\/93  

Microsoft Academic Search

Within the period of December 1992 to March 1993 lidar investigations of stratospheric aerosols were performed at Ny-Ålesund, Spitsbergen (79°N, 12°E). Backscatter signals at wavelengths of 353, 532, and 1064 nm and depolarization signals at 532 nm in altitudes ranging from the tropopause up to 30 km were analyzed. Throughout the whole measurement period we observed an aerosol layer of

Georg Beyerle; Roland Neuber; Otto Schrems; Folkard Wittrock; Bjørn Knudsen

1994-01-01

148

Lidar Measurements of Background Stratospheric Aerosol and Minor Volcanic Eruption Effects  

Microsoft Academic Search

Weekly lidar measurements of aerosol backscatter have been made at Mauna Loa Observatory, Hawaii and Boulder, Colorado. The measurements concentrate on the stratosphere and cover many years of background conditions. The period since 1996 is especially interesting since only minor injections of aerosol due to volcanic eruptions and forest fires have perturbed the background levels. These events are easily identified

J. E. Barnes; D. J. Hofmann; M. O'Neill; E. Dutton

2008-01-01

149

UV lidar measurements of the stratospheric aerosol layer and comparison with other optical data  

NASA Astrophysics Data System (ADS)

After the violent volcanic eruptions of El Chichon in Mexico (17.33 deg. N, 93.20 deg. W) in late March and early April 1982, enhanced stratospheric aerosols have been monitored by ruby (lasing wavelength lambda=694.3 nm) or Nd:YAG lidars (lambda=1064 or 532 nm). By these lidars, visible or near-infrared optical informations of stratospheric aerosols and their space-time variations can be obtained. It is usually difficult to measure the background level of stratospheric aerosols by an ultraviolet (UV) lidar, since Rayleigh scattering prevails over Mie scattering in the stratosphere. However, after the large volcanic eruptions, UV lidar measurements of stratospheric aerosols are possible. In order to obtain UV optical properties of stratospheric aerosols, measurements have been made at Fukuoka (33.65 deg. N, 130.35 deg. E) by a p-terphenyl dye laser at a wavelength of 340.5 nm. Observational results during October 1982, through May 1983, are shown and are compared with the results obtained by a ruby lidar at Tsukuba (36.05 deg. N, 140.13 deg. E).

Uchino, O.

1985-12-01

150

UV Raman lidar measurements of relative humidity for the characterization of cirrus cloud microphysical properties  

NASA Astrophysics Data System (ADS)

Raman lidar measurements performed in Potenza by the Raman lidar system BASIL in the presence of cirrus clouds are discussed. Measurements were performed on 6 September 2004 in the frame of Italian phase of the EAQUATE Experiment. The major feature of BASIL is represented by its capability to perform high-resolution and accurate measurements of atmospheric temperature and water vapour, and consequently relative humidity, both in daytime and night-time, based on the application of the rotational and vibrational Raman lidar techniques in the UV. BASIL is also capable to provide measurements of the particle backscatter and extinction coefficient, and consequently lidar ratio (at the time of these measurements only at one wavelength), which are fundamental to infer geometrical and microphysical properties of clouds. A case study is discussed in order to assess the capability of Raman lidars to measure humidity in presence of cirrus clouds, both below and inside the cloud. While air inside the cloud layers is observed to be always under-saturated with respect to water, both ice super-saturation and under-saturation conditions are found inside these clouds. Upper tropospheric moistening is observed below the lower cloud layer. The synergic use of the data derived from the ground based Raman Lidar and of spectral radiances measured by the NAST-I Airborne Spectrometer allows to determine the temporal evolution of the atmospheric cooling/heating rates due to the presence of the cirrus cloud anvil. Lidar measurements beneath the cirrus cloud layer have been interpreted using a 1-D cirrus cloud model with explicit microphysics. The 1-D simulations indicates that sedimentation-moistening has contributed significantly to the moist anomaly, but other mechanisms are also contributing. This result supports the hypothesis that the observed mid-tropospheric humidification is a real feature which is strongly influenced by the sublimation of precipitating ice crystals. Results illustrated in this study demonstrate that Raman lidars, like the one used in this study, can resolve the spatial and temporal scales required for the study of cirrus cloud microphysical processes and appears sensitive enough to reveal and quantify upper tropospheric humidification associated with cirrus cloud sublimation.

di Girolamo, P.; Summa, D.; Lin, R.-F.; Maestri, T.; Rizzi, R.; Masiello, G.

2009-07-01

151

UV Raman lidar measurements of relative humidity for the characterization of cirrus cloud microphysical properties  

NASA Astrophysics Data System (ADS)

Raman lidar measurements performed in Potenza by the Raman lidar system BASIL in the presence of cirrus clouds are discussed. Measurements were performed on 6 September 2004 in the frame of the Italian phase of the EAQUATE Experiment. The major feature of BASIL is represented by its capability to perform high-resolution and accurate measurements of atmospheric temperature and water vapour, and consequently relative humidity, both in daytime and night-time, based on the application of the rotational and vibrational Raman lidar techniques in the UV. BASIL is also capable to provide measurements of the particle backscatter and extinction coefficient, and consequently lidar ratio (at the time of these measurements, only at one wavelength), which are fundamental to infer geometrical and microphysical properties of clouds. A case study is discussed in order to assess the capability of Raman lidars to measure humidity in presence of cirrus clouds, both below and inside the cloud. While air inside the cloud layers is observed to be always under-saturated with respect to water, both ice super-saturation and under-saturation conditions are found inside these clouds. Upper tropospheric moistening is observed below the lower cloud layer. The synergic use of the data derived from the ground based Raman Lidar and of spectral radiances measured by the NAST-I Airborne Spectrometer allows the determination of the temporal evolution of the atmospheric cooling/heating rates due to the presence of the cirrus cloud. Lidar measurements beneath the cirrus cloud layer have been interpreted using a 1-D cirrus cloud model with explicit microphysics. The 1-D simulations indicate that sedimentation-moistening has contributed significantly to the moist anomaly, but other mechanisms are also contributing. This result supports the hypothesis that the observed mid-tropospheric humidification is a real feature which is strongly influenced by the sublimation of precipitating ice crystals. Results illustrated in this study demonstrate that Raman lidars, like the one used in this study, can resolve the spatial and temporal scales required for the study of cirrus cloud microphysical processes and appear sensitive enough to reveal and quantify upper tropospheric humidification associated with cirrus cloud sublimation.

di Girolamo, P.; Summa, D.; Lin, R.-F.; Maestri, T.; Rizzi, R.; Masiello, G.

2009-11-01

152

Evaluation of the solar-blind effect in ultraviolet ozone lidar with Raman lasers  

Microsoft Academic Search

Performances of differential absorption ozone lidars with ultraviolet Raman lasers are evaluated by a numerical simulation taking into account the solar-blind effect of stratospheric ozone for daytime observation; they are compared with observations. Calculations predict an ozone density profile up to 5 km in altitude determined during daylight using first and second Stokes lines of H2, and up to 30

Takashi Shibata; Terunobu Fukuda; Tohru Narikiyo; Mitsuo Maeda

1987-01-01

153

Observations of water vapor by ground-based microwave radiometers and Raman lidar  

Microsoft Academic Search

In November to December 1991, a substantial number of remote sensors and in situ instruments were operated together in Coffeyville, Kansas, during the climate experiment FIRE II. Included in the suite of instruments were (1) the NOAA Environmental Technology Laboratory (ETL) three-channel microwave radiometer, (2) the NASA GSFC Raman lidar, (3) ETL radio acoustic sounding system (RASS), and (4) frequent,

Yong Han; J. B. Snider; E. R. Westwater; S. H. Melfi; R. A. Ferrare

1994-01-01

154

Evidence of seasonally dependent stratosphere-troposphere exchange and purging of lower stratospheric aerosol from a multiyear lidar data set  

Microsoft Academic Search

Tropospheric and lower stratospheric aerosol backscatter data obtained from a calibrated backscatter lidar at Pasadena, California (34 deg N latitude) over the 1984-1993 period clearly indicate tightly coupled aerosol optical properties in the upper troposphere and lower stratosphere in the winter and early spring, due to the active midlatitude stratospheric-tropospheric (ST) exchange processes occurring at this time of year. Lidar

Robert T. Menzies; David M. Tratt

1995-01-01

155

Continuous observations of Asian dust and other aerosols by polarization lidars in China and Japan during ACE-Asia  

Microsoft Academic Search

Continuous observations of aerosols in China and Japan were made by polarization lidars during March to May 2001, corresponding with the Asian Pacific Regional Aerosol Characterization Experiment (ACE-Asia) field campaign period. Lidars in Beijing, Nagasaki, and Tsukuba were continuously operated regardless of weather conditions. Scatterers in the atmosphere were categorized for all vertical profiles, and occurrence frequencies of dust, spherical

Atsushi Shimizu; Nobuo Sugimoto; Ichiro Matsui; Kimio Arao; Itsushi Uno; Toshiyuki Murayama; Naoki Kagawa; Kazuma Aoki; Akihiro Uchiyama; Akihiro Yamazaki

2004-01-01

156

Remote sensing of atmosphere with aircraft borne lidar systems  

NASA Astrophysics Data System (ADS)

Spatial and temporal distribution of clouds and aerosols are measured by lidar. Their optical properties are evaluated using additional assumptions. Wind velocities are mapped by backscatter Doppler lidar systems. Raman lidars are to be used for the supervision of factory emissions. It is shown that Differential Absorptions Lidar (DIAL) systems offer considerable physical advantages in measuring atmospheric constituents; experiences with an airborne device are described.

Ehret, Gerhard; Renger, Wolfgang; Roesler, Uwe; Kiemle, Christian; Simmet, Georg; Ruppersberg, Gerhard

1991-09-01

157

Detection of stratospheric sulfuric Acid aerosols with polarization lidar: theory, simulations, and observations.  

PubMed

The derivation of backscatter ratio profiles from polarization lidar measurements is discussed. The method is based on differences in depolarization between molecular backscattering and backscattering from spherical aerosol particles. Simulations show that the polarization algorithms yield backscatter ratios with uncertainties comparable with those obtained by Klett's method, provided that the backscattering process is dominated by molecular scattering. The technique could be utilized for monitoring the stratospheric sulfuric acid aerosol layer during periods of background conditions. The polarization analysis method is discussed in light of simulation results and is applied to polarization lidar profiles observed during the ALBATROSS 1996 field measurement campaign. PMID:18350097

Beyerle, G

2000-09-20

158

Comparative study of the aerosol properties measured by two-wavelength lidar and detector on balloon  

NASA Astrophysics Data System (ADS)

Analyses are made of atmospheric aerosol measurements effected with 1.06 and 0.53 micron lidar beams from a YAG laser. Two wavelengths were used to track the projected bimodal aerosol particulate size distribution which typified the El Chichon stratospheric plume. Data were gathered from a balloon-borne instrument platform 3 km above the tropopause to validate the ground-based lidar data. Numerical techniques for obtaining normalized backscattering profiles are reviewed, including size distribution estimations. An examination of latitudinal size distribution revealed that latitudinal stratospheric concentrations, although equal after 4 mos, diverged thereafter, with lower latitude concentrations becoming twice as great as middle latitude concentrations.

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

1985-04-01

159

Development of a deployable aerosol/water vapor lidar to characterize the atmosphere  

NASA Astrophysics Data System (ADS)

A trailer-based lidar, named Humidity and Aerosol Lidar (HAL), is being built as a remote sensing tool to characterize atmospheric aerosol and water vapor in the line-of-sight. Water vapor and aerosol in the lower atmosphere are critical components affecting the propagation of high-energy laser beams and microwave. The sensor is developed to collect high temporal and vertical resolution data of atmospheric aerosols and water vapor. This ground-based system also serves as a demonstration and an engineering study of a flight-capable sensor for real-time diagnostic of the atmosphere. The lidar, operating on the principles of differential absorption, could measure water vapor to 10 km altitudes. It also measures aerosols and cloud backscatter at altitudes up to 18 km and ranges up to 90 km. Operating with a hemispherical scanner, the sensor could map the 3-dimensional field of aerosols and water vapor and provide vertical as well as horizontal structures. A unidirectional Alexandrite ring laser, operating in single mode near 727.49 nm, is the laser source. The sensor is designed to operate in day and night time. A description of the system, its wavelength calibration unit, the transmitter-receiver system and projected performance will be discussed. Results of the photo-acoustic calibration cell and wavelength selections will be presented. Preliminary results of water vapor and aerosols will be discussed.

Dao, Phan D.; Dentamaro, Anthony

2003-09-01

160

Observed effects of particles nonsphericity on the retrieval of marine and desert dust aerosol optical depth by lidar  

Microsoft Academic Search

Polarization lidar observations of maritime and Saharan dust aerosols collected at Crete (35.5°N–23.7°E) during the May 1999 PAUR II campaign are discussed. Lidar traces are inverted and integrated to provide aerosol optical depth at 532 nm. Two model relationships linking together aerosol backscatter and extinction coefficients are employed to perform such an inversion: one obtained employing the Mie theory, i.e.,

G. P Gobbi; F Barnaba; M Blumthaler; G Labow; J. R Herman

2002-01-01

161

Atmospheric measurements using a scanning, solar-blind Raman Lidar.  

National Technical Information Service (NTIS)

The study of the water cycle by Lidar has many applications. Because micro-scale structures can be identified by their water content, the technique offers new opportunities to visualize and study the phenomena. There are applications to many practical pro...

W. E. Eichinger D. I. Cooper D. B. Holtkamp R. R. Karl C. R. Quick

1991-01-01

162

Using CALIPSO's ocean surface lidar return signal and AMSR-E wind fields to determine oceanic aerosol type distributions  

NASA Astrophysics Data System (ADS)

Oceanic aerosol loading and type have implications for ocean productivity/health, atmospheric radiative transfer, air-quality models and forecasts, and such biogeochemical processes as ocean iron fertilization. CALIPSO aerosol subtyping studies have shown that most natural and anthropogenic aerosol types are found over the ocean with varying frequency and abundance. The aerosol types found over the ocean span a wide range of radiative impacts from highly absorbing (biomass burning smoke) to highly scattering (non-seasalt sulfates, seasalt, some dusts etc). Since marine aerosol transport and generation phenomena are impacted by the wind patterns and continental sources, the aerosol types over the ocean tend to be regional and have significant differences in optical characteristics over the remote oceans and coastal regions. Relationships between wave slope variance and wind speed, based on comparison between CALIPSO lidar sea surface backscatter and collocated Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR-E) wind speed measurements have been established by Hu et al (2007). In this study, we use collocated sea surface backscatter measurements from CALIPSO and AMSR-E wind speed measurements to determine atmospheric column optical depth over the ocean. We then derive the aerosol column optical depth and use it to constrain the CALIPSO lidar attenuated backscatter measurements to derive lidar ratios. Aerosol lidar ratio is an intensive property and is related to aerosol type. The lidar ratios derived from the column optical depth are matched to known aerosol models obtained from AERONET observations to obtain global aerosol subtype distributions. Mapping the aerosol subtype distributions over the oceans will improve the wind speed retrieval from the lidar surface signal since atmospheric attenuation by aerosols contributes the largest uncertainty. CALIPSO has been in orbit long enough to obtain type segregated seasonal and zonal oceanic aerosol distributions for use in studies of ocean productivity and dust aerosol fluxes to the oceans. These results are compared to CALIPSO’s conventional aerosol subtyping products.

Omar, A. H.; Hu, Y.; Vaughan, M.; Liu, Z.; Trepte, C. R.; Winker, D. M.; Josset, D. B.

2009-12-01

163

Lidar observations of Kasatochi volcano aerosols in the troposphere and stratosphere  

Microsoft Academic Search

The eruption of Kasatochi volcano on 7–8 August 2008 injected material into the troposphere and lower stratosphere of the northern midlatitudes during a period of low stratospheric aerosol background concentrations. Aerosols from the volcanic plume were detected with a lidar in Halifax, Nova Scotia (44.64°N, 63.59°W) 1 week after the eruption and for the next 4 months thereafter. The volcanic

L. Bitar; T. J. Duck; N. I. Kristiansen; A. Stohl; S. Beauchamp

2010-01-01

164

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

165

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

166

Ground-truth aerosol lidar observations: can the Klett solutions obtained from ground and space be equal for the same aerosol case?  

SciTech Connect

Upcoming multiyear satellite lidar aerosol observations need strong support by a worldwide ground-truth lidar network. In this context the question arises as to whether the ground stations can deliver the same results as obtained from space when the Klett formalism is applied to elastic backscatter lidar data for the same aerosol case. This question is investigated based on simulations of observed cases of simple and complex aerosol layering. The results show that the differences between spaceborne and ground-based observations can be as large as20% for the backscatter and extinction coefficients and the optimum estimates of the column lidar ratios. In cases with complex aerosol layering, the application of the two-layer approach can lead to similar results (space, ground) and accurate products provided that horizontally homogeneous aerosol conditions are given.

Ansmann, Albert

2006-05-10

167

Subtropical cirrus cloud extinction to backscatter ratios measured by Raman Lidar during CAMEX-3  

NASA Astrophysics Data System (ADS)

The NASA/GSFC Scanning Raman Lidar was stationed on Andros Island, Bahamas for the third Convection and Moisture Experiment (CAMEX 3) held in August-September, 1998 and acquired an extensive set of cirrus cloud measurements [Whiteman et al., 2001]. Distinct differences in the optical properties of the clouds are found when the cirrus are hurricane-induced versus non-hurricane-induced. Hurricane-induced cirrus clouds are found to generally possess lower values of extinction-to-backscatter ratio (S) than non-hurricane-induced clouds. Comparison of the S measurements made here with those of other studies reveal at times large differences. Given that S is often a required parameter for space-based retrievals of cloud optical depth using backscatter lidar, these large differences in S measurements imply difficulties in developing a parameterization of S for use in space-based lidar retrievals.

Whiteman, D. N.; Demoz, B.; Wang, Z.

2004-06-01

168

Versatile lidar for atmospheric studies, including plume dispersion, clouds, and stratospheric aerosol  

NASA Astrophysics Data System (ADS)

A transportable scanning lidar for studying clouds, plume dispersion, and stratospheric aerosol at any of three wavelengths is described. A ruby laser transmits linearly polarized light of 694.3 nm wavelength at a maximum 0.8/s pulse rate. The lidar can discriminate between parallel, orthogonal, or combined polarizations of backscatter in a multichannel receiver. A frequency-doubled Nd:YAG laser, emitting at 532.0 nm and at a maximum pulse rate of 10/s, normally performs mapping of plume structure. Range resolution, including response, is less than 7 m. The sample interval is typically 3 m for plume experiments and 15 m for stratospheric aerosol profiles. Beam divergence is less than 1.0 mrad, and the receiver's field of view is adjustable up to 6 mrad. The lidar's sensitivity can be altered over a wide dynamical range by selection of optical filters in the receiver and adjustments in the photomultiplier voltage.

Eberhard, W. L.; McNice, G. T.

1986-12-01

169

Discrimination of aerosol species by correlated lidar and sunphotometer measurements in the Paris megacity suburban area  

NASA Astrophysics Data System (ADS)

This unprecedented study of daytime measurements performed over 3 years (2007-2010) with a robust commercial lidar (ALS 450, www.leosphere.com) installed ~20 km south of Paris (instrumented site of Palaiseau - SIRTA) and coupled with a sunphotometer, shows that differing optical properties allow the discrimination of several families in the observed aerosol content. While the lidar performed resolved measurements in the atmospheric column at 355 nm wavelength every 5 minutes with a vertical resolution of 15 m, the sunphotometer, which is part of the AERONET network, provided the spectral atmospheric transmittance between 340 and 1020 nm. Correlating the lidar and sunphotometer measurements opens interesting prospects for the detection of the main pollution events around the megacity of Paris. The Lidar Ratio (LR), the depolarization ratio (?) and the Angström coefficient (A) characterize specific aerosol optical properties and may sign their origins. They are retrieved from the instruments on clear days, as an average in the tropospheric column over a few minutes. Scatter plots along these parameters show that Parisian pollutants dominate the scene, with familiar properties corresponding to previous findings (LR~70 sr-1, A~1). In some meteorological conditions, aerosol pollutants are observed which present different optical properties. We discuss these results in the light of known events in the survey time-line and conclude on the capabilities for identification of aged aerosols trapped within long range transport processes.

Totems, J.; Royer, P.; Chazette, P.; Haeffelin, M.; Pietras, C.

2012-04-01

170

ELF and ALEX SURF WINTER WAVES: Lidar Intercomparison of Aerosol and Water Vapor Measurements in the Baltimore-Washington Metropolitan Area During the Winter Water Vapor Validation Experiments (WAVES) 2008 campaign.  

NASA Astrophysics Data System (ADS)

Elastic and Raman lidar measurements were conducted to measure the vertical distribution of aerosols and water vapor during the Water Vapor Validation Experiments (WAVES) 2008 campaign by the University of Maryland Baltimore County (UMBC) Atmospheric Lidar Group at UMBC, at the same time as measurements at Howard University's Beltsville Research Station (26.5 km distant). The lidar profiles of atmospheric water vapor and aerosols allowed comparison for AURA/Aqua retrieval studies, by performing instrument accuracy assessments and data, generated by various independent active and passive remote sensing instruments for case studies of regional water vapor and aerosol sub-pixel variability. Integration of the lidar water vapor mixing ratios has been carried out to generate a column precipitable water vapor timeseries that can be compared to UMBC's SUOMINET station and Baltimore Bomem Atmospheric Emitted Radiance Interferometer (BBAERI). Changes in atmospheric aerosol concentration and water vapor mixing ratios due to meteorological events observed in the lidar timeseries have been correlated to the vertical temperature timeseries of BBAERI and to modeling of the air mass over the Baltimore-Washington metro area with the Weather Research and Forecasting (WRF) model.

Delgado, R.; Weldegaber, M.; Wilson, R. C.; McMillan, W.; McCann, K. J.; Woodman, M.; Demoz, B.; Adam, M.; Connell, R.; Venable, D.; Joseph, E.; Rabenhorst, S.; Twigg, L.; McGee, T.; Whiteman, D. N.; Hoff, R. M.

2008-12-01

171

Raman Lidar Transmissometer Data Processing in Real Time.  

National Technical Information Service (NTIS)

A minicomputer with 8K memory was interfaced with a pulsed nitrogen laser Raman Transmissometer to provide real time data processing and display capability. Self-calibration, normalization and ambient background substraction are included in the minicomput...

B. Caputo D. A. Leonard

1973-01-01

172

Novel Co:MgF2 Lidar for Aerosol Profiler.  

National Technical Information Service (NTIS)

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:Mg...

M. A. Acharekar

1993-01-01

173

Observations of water vapor by ground-based micro-wave radiometers and Raman lidar  

NASA Astrophysics Data System (ADS)

In November to December 1991, a substantial number of remote sensors and in situ instruments were operated together in Coffeyville, Kansas, during the climate experiment FIRE II. Included in the suite of instruments were (1) the NOAA Environmental Technology Laboratory (ETL) three-channel microwave radiometer, (2) the NASA GSFC Raman lidar, (3) ETL radio acoustic sounding system (RASS), and (4) frequent, research-quality radiosondes. The Raman lidar operated only at night and the focus of this portion of the experiment concentrated on clear conditions. The lidar data, together with frequent radiosondes and measurements of temperature profiles (every 15 min) by RASS allowed profiles of temperature and absolute humidity to be estimated every minute. We compared 2-min measurements of brightness temperature (Tb) with calculations of Tb that were based on the Liebe and Lay ton (1987) and Liebe et al. (1993) microwave propagation models, as well as the Waters (1976) model. The comparisons showed the best agreement at 20.6 GHz with the Waters model, with the Liebe et al. (1993) model being best at 31.65 GHz. The results at 90 GHz gave about equal success with the Liebe and Layton (1987) and Liebe et al. (1993) models. Comparisons of precipitable water vapor derived independently from the two instruments also showed excellent agreement, even for averages as short as 2 min. The rms difference between Raman and radiometric determinations of precipitable water vapor was 0.03 cm which is roughly 2%. The experiments clearly demonstrate the potential of simultaneous operation of radiometers and Raman lidars for fundamental physical studies of water vapor.

Han, Yong; Snider, J. B.; Westwater, E. R.; Melfi, S. H.; Ferrare, R. A.

1994-09-01

174

1D-VAR Retrieval of Aerosol Properties from Satellite Spectral Lidar and Radiometric Observations  

NASA Astrophysics Data System (ADS)

Aerosols play an important role in atmospheric physics and chemistry through their impact on air pollution, actinic fluxes, visibility, acid rain, and climate. Numerous atmospheric models at the urban, regional or global scale include a representation of aerosols aimed at simulating their physical and chemical properties such as their concentration, size distribution, chemical composition and state of mixture. Unfortunately these models are not well constrained by observations, which limits the possibility of accurate operational forecasts of aerosol properties at these different scales. Important progresses have been made in the observation of aerosols (in clear-sky) from space. One can measure with a good accuracy the aerosol optical depth and the Ångström exponent (a signature of aerosol size) from radiometric measurements in the visible over the ocean and to some extent over land. Active remote-sensing by lidar offer an opportunity to measure the aerosol vertical profile. In this work we use a simple 1D radiative transfer model and its adjoint to study the retrieval of the vertical profile of aerosol properties from variational assimilation of spectral lidar and radiometric measurements. The cost function is minimized using a BFGS algorithm forcing the model towards the observations. Results of this one dimensional variational assimilation (1D-VAR) scheme with synthetic satellite measurements will be presented and analyzed. In particular we will focus on the retrieval of aerosol properties such as the extinction coefficient vertical profile and size distribution of the accumulation and coarse modes. Colocated lidar and radiance data from the GLAS and MODIS instruments will be used to test the algorithm.

Huneeus, N.; Boucher, O.; Bocquet, M.; Sportisse, B.

175

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

176

Multiwavelength lidar measurements of stratospheric aerosols above Spitsbergen during winter 1992/93  

SciTech Connect

Using a multiwavelength lidar the authors measured aerosols from the tropopause to altitudes of 30 km in the period December 1992 to March 1993. They analyzed backscatter and depolarization measurements to infer information on aerosol size and phase. During most of this period they saw evidence of a liquid drop aerosol layer in the lower stratosphere which was of a volcanic origin. In January they observed polar stratospheric clouds on numerous occasions, and particle size was found to depend strongly on the cooling rate.

Beyerle, G.; Neuber, R.; Schrems, O. (Alfred Wegener Institute for Polar and Marine Research, Bremerhaven (Germany)); Wittrock, F. (Univ. of Bremen (Germany)); Knudsen, B. (Danish Meteorological Institute, Copenhagen (Denmark))

1994-01-01

177

Polarization lidar returns from aerosols and thin clouds: a framework for the analysis.  

PubMed

Relationships for the interpretation of polarization lidar observations of aerosols and thin clouds are presented. They allow for the separation of contributions to backscatter from solid and liquid phases by the use of either the classical backscatter and depolarization ratio parameters or the particulate cross-polarized backscatter cross sections. It is shown that different aerosol phases can be better separated by use of the latter coordinates. Emphasis is placed on the study of composition and phase properties of polar stratospheric aerosols. PMID:18286035

Gobbi, G P

1998-08-20

178

Aerosol size distribution and refractive index from bistatic lidar angular scattering measurements in the surface layer  

SciTech Connect

The results of an inversion method by iteration for determining the aerosol size distribution and the refractive index of atmospheric aerosols in the surface layer from bistatic lidar angular scattering measurements, followed by a brief description of the experimental and data retrieval techniques are presented. The continuous wave, bistatic Argon ion lidar at the Indian Institute of Tropical Meteorology (IITM), Pune (18{degree}31{prime}N, 73{degree}51{prime}E, 559 m AMSL), India has been used for the measurements. Results of the analysis of 420 samples collected over a 7 years` period indicate mean value of size and refractive indices of 4.0 and 1.6, respectively, with greater fraction of larger particles during premonsoon while smaller particles during post-monsoon months at the lidar site. The retrieved aerosol parameters are compared with those determined from spectroradiometer observations at the same site. The results are found well in agreement with those obtained previously by the authors using the library search method. The above observations of angular distribution of scattered intensity are used with an aerosol model to infer the dominant type of aerosols present in the environment in and around the experimental station.

Pandithurai, G.; Devara, P.C.S.; Raj, P.E.; Sharma, S. [Indian Inst. of Tropical Meteorology, Pune (India)

1996-05-01

179

Initial Results of the Cloud, Aerosol Polarization and Backscatter Lidar at Summit, Greenland  

NASA Astrophysics Data System (ADS)

Measurements of cloud properties over Summit, Greenland are necessary to document the full range of cloud conditions and characteristics throughout the Arctic. A new lidar system has been developed to measure depolarization and backscatter of clouds in the lower troposphere and aerosols in the upper troposphere and lower stratosphere. This lidar uses recent developments in optical methods to characterize system polarization effects in order to compensate for systematic phase shifts. The lidar utilizes the detection of three polarization planes to determine the depolarization ratio and diattenuation of clouds and aerosols below 2.5% error. The ability to measure diattenuation allows for a qualitative assessment of particle orientation and analysis of the data that can forego the assumption of randomly oriented particles. The lidar is located at Summit, Greenland as part of the Integrated Characterization of Energy, Clouds, Atmospheric State, and Precipitation at Summit project and NOAA’s Global Monitoring Division’s stratospheric lidar network. Initial results from the first six months of operation suggest cloud formation similar to other Arctic sites. Here we particularly look at the persistence of mixed phase clouds and new results suggesting possible ice crystal alignment under certain atmospheric conditions.

Neely, R. R.; Hayman, M.; Thayer, J.; Hardesty, R.; O'Neill, M.; Shupe, M.

2010-12-01

180

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

181

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

182

Aerosol dynamics monitoring for cosmic ray observatories by a micro pulse lidar  

NASA Astrophysics Data System (ADS)

Monitoring of an atmosphere using a micro pulse lidar for application in the detection of extremely high-energy cosmic rays by the fluorescence technique, in the Pierre Auger Project, is discussed. The field experiment data of the aerosol dynamics, like the cloud height, the extinction coefficient measurements and the atmospheric homogeneity estimation, using the compact lidar with a high repetition rate of 40 nJ pulses, is presented. The sharp modulation of the atmospheric transparency along the horizontal path and in the vertical backscattering profile is detected at the Malargüe site of the Pierre Auger Observatory, in Argentina.

Pershin, S.; Lyash, A.; Nunes, R.; Shellard, R.; Tabares, R.

183

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

184

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

185

Altitude and seasonal characteristics of aerosol backscatter at thermal infrared wavelengths using lidar observations from coastal California  

Microsoft Academic Search

A calibrated CO2 lidar has been used to measure boundary layer aerosol backscatter and vertical profiles of tropospheric and lower stratospheric aerosol backscatter over a 1984-1987 time period from a site in Pasadena, California. The lidar data have been taken at two wavelengths, 9.25 and 10.6 microns. Data are presented which show altitude, seasonal, and trend characteristics of backscatter for

Robert T. Menzies; Gerard M. Ancellet; David M. Tratt; Morton G. Wurtele; Jeffrey C. Wright

1989-01-01

186

Comparison of ambient aerosol extinction coefficients obtained from in-situ, MAX-DOAS and LIDAR measurements at Cabauw  

NASA Astrophysics Data System (ADS)

In the field, aerosol in-situ measurements are often performed under dry conditions (relative humidity RH<30-40%). Since ambient aerosol particles experience hygroscopic growth at enhanced RH, their microphysical and optical properties - especially the aerosol light scattering - are also strongly dependent on RH. The knowledge of this RH effect is of crucial importance for climate forcing calculations or for the comparison of remote sensing with in-situ measurements. Here, we will present results from a four-month campaign which took place in summer 2009 in Cabauw, The Netherlands. The aerosol scattering coefficient ?sp(?) was measured dry and at various, predefined RH conditions between 20 and 95% with a humidified nephelometer. The scattering enhancement factor f(RH,?) is the key parameter to describe the effect of RH on ?sp(?) and is defined as ?sp(RH,?) measured at a certain RH divided by the dry ?sp(dry,?). The measurement of f(RH,?) together with the dry absorption measurement (assumed not to change with RH) allows the determination of the actual extinction coefficient ?ep(RH,?) at ambient RH. In addition, a wide range of other aerosol properties were measured in parallel. The measurements were used to characterize the effects of RH on the aerosol optical properties. A closure study showed the consistency of the aerosol in-situ measurements. Due to the large variability of air mass origin (and thus aerosol composition) a simple parameterization of f(RH,?) could not be established. If f(RH,?) needs to be predicted, the chemical composition and size distribution need to be known. Measurements of four MAX-DOAS (multi-axis differential optical absorption spectroscopy) instruments were used to retrieve vertical profiles of ?ep(?). The values of the lowest layer were compared to the in-situ values after conversion of the latter ones to ambient RH. The comparison showed a good correlation of R2 = 0.62-0.78, but the extinction coefficients from MAX-DOAS were a factor of 1.5-3.4 larger than the in-situ values. Best agreement is achieved for a few cases characterized by low aerosol optical depths and low planetary boundary layer heights. Differences were shown to be dependent on the applied MAX-DOAS retrieval algorithm. The comparison of the in-situ extinction data to a Raman LIDAR (light detection and ranging) showed a good correlation and higher values measured by the LIDAR (R2 = 0.82-0.85, slope of 1.69-1.76) if the Raman retrieved profile was used to extrapolate the directly measured extinction coefficient to the ground. The comparison improved if only nighttime measurements were used in the comparison (R2 = 0.96, slope of 1.12).

Zieger, P.; Weingartner, E.; Henzing, J.; Moerman, M.; de Leeuw, G.; Mikkilä, J.; Ehn, M.; Petäjä, T.; Clémer, K.; van Roozendael, M.; Yilmaz, S.; Frieß, U.; Irie, H.; Wagner, T.; Shaiganfar, R.; Beirle, S.; Apituley, A.; Wilson, K.; Baltensperger, U.

2011-03-01

187

Lidar development with applications to the stratosphere- troposphere exchange and tropical aerosol detection  

NASA Astrophysics Data System (ADS)

Lidar remote sensing of the atmosphere is explored through the use and development of the Rayleigh and resonance lidar systems at the Arecibo Observatory (18.3oN, 66.8oW). Resonance lidar capabilities have been demonstrated at the Arecibo Observatory for both sodium and potassium. The initiation, development, and details of the lidar system, based on an alexandrite solid state ring laser, are discussed. We present initial resonance observations, as well as the exciting potential for dual- wavelength upper troposphere and lower stratosphere aerosol observations. The Arecibo five year Rayleigh lidar data base and latitudinal snap shot from the Space Shuttle LITE experiment are used to study the temporal and spatial distributions of volcanic aerosols entrained in the stratosphere. The results support recent global models which suggest an extra tropical suction pump is responsible for mass being up drawn across the tropical tropopause, moved poleward, then pushed downward in the extratropics (Holton et al., 1995). The aerosol scattering wavelength dependence is introduced through the Angstrom coefficient to estimate aerosol size distributions. The analysis is extended to upper tropospheric cirrus clouds. Initial observations of two types of cirrus are presented. We speculate that one type are the remnants of convective activity, while the second grow in the cold tropical tropopause. We present a single example of the wavelength dependence as an example of the utility of multi-wavelength lidar analysis. Local stratospheric/tropospheric exchanges are investigated through a detailed discussion of lidar, radar, and balloon observations of temperatures and wind field fluctuations. On a single remarkable night, September 14-15, 1994, we captured two unique examples of convective activity at the tropopause and in the lower stratosphere. The first is a large scale molecular density depletion (temperature enhancement) just below the tropopause, which we believe is the result of strong convective parcels which are trapped at the tropopause inversion. The second example are temperature steps in the lower stratosphere that are hypothesized to have been caused by overshooting convective parcels from a frontal line some 200 km upwind of our location.

Castleberg, Paul Andrew

1997-06-01

188

Optical, microphysical, mass and geometrical properties of aged volcanic particles observed over Athens, Greece, during the Eyjafjallajökull eruption in April 2010 through synergy of Raman lidar and sunphotometer measurements  

NASA Astrophysics Data System (ADS)

Vertical profiles of the optical (extinction and backscatter coefficients, lidar ratio and Ångström exponent), microphysical (mean effective radius, mean refractive index, mean number concentration) and geometrical properties as well as the mass concentration of volcanic particles from the Eyjafjallajökull eruption were retrieved at selected heights over Athens, Greece, using multi-wavelength Raman lidar measurements performed during the period 21-24 April 2010. Aerosol Robotic Network (AERONET) particulate columnar measurements along with inversion schemes were initialized together with lidar observations to deliver the aforementioned products. The well-known FLEXPART (FLEXible PARTicle dispersion model) model used for volcanic dispersion simulations is initiated as well in order to estimate the horizontal and vertical distribution of volcanic particles. Compared with the lidar measurements within the planetary boundary layer over Athens, FLEXPART proved to be a useful tool for determining the state of mixing of ash with other, locally emitted aerosol types. The major findings presented in our work concern the identification of volcanic particles layers in the form of filaments after 7-day transport from the volcanic source (approximately 4000 km away from our site) from the surface and up to 10 km according to the lidar measurements. Mean hourly averaged lidar signals indicated that the layer thickness of volcanic particles ranged between 1.5 and 2.2 km. The corresponding aerosol optical depth was found to vary from 0.01 to 0.18 at 355 nm and from 0.02 up to 0.17 at 532 nm. Furthermore, the corresponding lidar ratios (S) ranged between 60 and 80 sr at 355 nm and 44 and 88 sr at 532 nm. The mean effective radius of the volcanic particles estimated by applying inversion scheme to the lidar data found to vary within the range 0.13-0.38 ?m and the refractive index ranged from 1.39+0.009i to 1.48+0.006i. This high variability is most probably attributed to the mixing of aged volcanic particles with other aerosol types of local origin. Finally, the LIRIC (LIdar/Radiometer Inversion Code) lidar/sunphotometric combined inversion algorithm has been applied in order to retrieve particle concentrations. These have been compared with FLEXPART simulations of the vertical distribution of ash showing good agreement concerning not only the geometrical properties of the volcanic particles layers but also the particles mass concentration.

Kokkalis, P.; Papayannis, A.; Amiridis, V.; Mamouri, R. E.; Veselovskii, I.; Kolgotin, A.; Tsaknakis, G.; Kristiansen, N. I.; Stohl, A.; Mona, L.

2013-09-01

189

Airborne CO(2) coherent lidar for measurements of atmospheric aerosol and cloud backscatter.  

PubMed

An airborne CO(2) coherent lidar has been developed and flown on over 30 flights of the NASA DC-8 research aircraft to obtain aerosol and cloud backscatter and extinction data at a wavelength near 9µm. Designed to operate in either zenith- or nadir-directed modes, the lidar can be used to measure vertical profiles of backscatter throughout the vertical extent of the troposphere and the lower stratosphere. Backscatter measurements in absolute units are obtained through a hard-target calibration methodology. The use of coherent detection results in high sensitivity and narrow field of view, the latter property greatly reducing multiple-scattering effects. Aerosol backscatter profile intercomparisons with other airborne and ground-based CO(2) lidars were conducted during instrument checkout flights over the NASA Ames Research Center before extended depolyment over the Pacific Ocean. Selected results from data taken during the flights over the Pacific Ocean are presented, emphasizing intercom arisons with backscatter profile data obtained at 1.06 µm with a NASA Goddard Space Flight Center Nd:YAG lidar on the same flights. PMID:20935971

Menzies, R T; Tratt, D M

1994-08-20

190

Results of site testing using an aerosol, backscatter lidar at the Roque de los Muchachos Observatory  

NASA Astrophysics Data System (ADS)

Because of the high quality of its sky, the Roque de los Muchachos Observatory (ORM), located on the island of La Palma in the Canary Islands, is home to many astronomical facilities. In the context of the Extremely Large Telescope Design Study, two intensive lidar campaigns were performed at the ORM near the Jacobus Kapteyn Telescope between 2007 July 9 and 11 and between 2008 May 26 and June 14. The goal of the campaign was to characterize the atmosphere in terms of the height of the planetary boundary layer (PBL) and the aerosol stratification versus synoptic conditions. Three typical synoptic situations were found, which supported the intrusion of aerosols from marine/oceanic, anthropogenic and Saharan origins, respectively. All measurements revealed a multilayer stratification with a mean PBL height of 546 +/- 198 m agl and top layers as high as ~8400 m asl. As a by-product, an estimate of the aerosol optical thickness was also obtained and compared to the total atmospheric extinction coefficient measured by the Carlsberg Meridian Telescope. Except in the presence of Saharan dust, the aerosol optical thickness is very low; the average values are 0.0405 at 532 nm and 0.0055 at 1064 nm. In the presence of Saharan dust, values of 0.233 and 0.157 were found at 532 and 1064 nm, respectively. The proportion of aerosol optical thickness contained in the layers above the PBL against that contained in the PBL is in all cases greater or equal to 50 per cent. This emphasizes the importance of the upper layers in the scattering and absorption of astronomical signals. Additionally, for the first time, spaceborne lidar measurements were also compared to those of a ground lidar, in order to evaluate the use of a spaceborne active instrument for aerosol content monitoring at an astronomical site.

Sicard, Michaël; Md Reba, M. Nadzri; Tomás, Sergio; Comerón, Adolfo; Batet, Oscar; Muñoz-Porcar, Constantino; Rodríguez, Alejandro; Rocadenbosch, Francisco; Muñoz-Tuñón, Casiana; Fuensalida, Jesús J.

2010-06-01

191

Lidar measurements of Raman scattering at ultraviolet wavelength from mineral dust over East Asia.  

PubMed

We developed a novel measurement channel that utilizes Raman scattering from silicon dioxide (SiO2) quartz at an ultraviolet wavelength (361 nm). The excitation of the Raman signals is done at the primary wavelength of 355 nm emitted from a lidar instrument. In combination with Raman signals from scattering from nitrogen molecules, we may infer the mineral-quartz-related backscatter coefficient. This technique thus allows us to identify in a comparably direct way the mineral quartz content in mixed pollution plumes that consist, e.g., of a mix of desert dust and urban pollution. We tested the channel for the complex situation of East Asian pollution. We find good agreement of the inferred mineral-quartz-related backscatter coefficient to results obtained with another mineral quartz channel which was operated at 546 nm (primary emission wavelength at 532 nm), the functionality of which has already been shown for a lidar system in Tsukuba (Japan). The advantage of the novel channel is that it provides a better signal-to-noise ratio because of the shorter measurement wavelength. PMID:21263697

Tatarov, Boyan; Müller, Detlef; Shin, Dong Ho; Shin, Sung Kyun; Mattis, Ina; Seifert, Patric; Noh, Young Min; Kim, Y J; Sugimoto, Nobuo

2011-01-17

192

Ozone and aerosol distribution above Mexico City measured with a DIAL/elastic lidar system during the Mexico City Metropolitan Area (MCMA) 2003 field campaign  

NASA Astrophysics Data System (ADS)

Ozone and aerosol vertical distribution and their time evolution were measured with a combined UV DIAL / 532-nm elastic lidar during the MCMA 2003 field campaign held in April-May 2003 in Mexico City Metropolitan Area (MCMA). The DIAL transmitter is based on a N2 Raman converter, pumped by the IVth harmonic of a Nd:YAG laser. The residual second harmonic radiation from the laser is used for aerosol measurements. In the DIAL part of the receiver a dual-telescope configuration ("Long" and "Short" range) is employed to reduce the dynamic range of the signals and a single 20 cm F/4 Newtonian type telescope is used for the aerosol observations at 532 nm. The DIAL wavelengths are transmitted coaxially to the long range telescope and the 532 nm beam is transmitted coaxially to the "aerosol" telescope. The DIAL receiver is equipped with a grating polychromator for spectral separation and the 532 nm receiver uses a narrowband (0.4 nm) interference filter. "Hamamatsu" 5783-06 photosensor modules detect all signals. Ozone concentration was measured to altitudes of up to 6 km AGL and aerosol to 14 km AGL. The height of the PBL was estimated from the aerosol measurements. The diurnal evolution of the PBL and ozone were studied during the campaign. Formation of a residual layer containing elevated ozone concentrations at nighttime, as well as detachment of the PBL in the late afternoon hours were observed.

Simeonov, Valentin; Ristori, Pablo; Taslakov, Marian; Dinoev, Todor; Molina, Luisa T.; Molina, Mario J.; van den Bergh, Hubert

2005-10-01

193

A height resolved global view of dust aerosols from the first year CALIPSO lidar measurements  

Microsoft Academic Search

Based on the first year of CALIPSO lidar measurements under cloud-free conditions, a height-resolved global distribution of dust aerosols is presented for the first time. Results indicate that spring is the most active dust season, during which ~20% and ~12% of areas between 0 and 60°N are influenced by dust at least 10% and 50% of the time, respectively. In

Dong Liu; Zhien Wang; Zhaoyan Liu; Dave Winker; Charles Trepte

2008-01-01

194

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

195

Numerical analysis of lidar-signal fluctuations due to large-scale inhomogeneities of atmospheric aerosol  

NASA Astrophysics Data System (ADS)

Expressions are derived for the mean value and correlation function of a lidar signal in the case of strong fluctuations of atmospheric parameters connected with aerosol inhomogeneities. Results obtained with formulas for weak and strong fluctuations are compared. The distribution law of backscatter signal fluctuations is examined, and it is shown that in most cases this law can be approximated by the log-normal law.

Gyngazov, S. A.; Kavkianov, S. I.; Krekov, G. M.

1985-08-01

196

Influence of Humidified Aerosol on Lidar Depolarization Measurements below Ice-Precipitating Arctic Stratus  

NASA Astrophysics Data System (ADS)

Lidar measurements obtained during the Surface Heat Budget of the Arctic Ocean (SHEBA) experiment under a mixed-phase stratus cloud that was lightly precipitating ice show a range of surprisingly low depolarization ratios (4%-23%), despite an absence of cloud droplets there. These depolarization ratios are much lower than the range of theoretical values obtained for various ice habits. The depolarization ratios correlate well with radar reflectivity, suggesting that the variation in depolarization ratios results from variations in ice water content, rather than variation in ice habits or orientation. By calculating lidar depolarization based on (i) large-eddy simulations and (ii) in situ ice size distribution measurements, it is shown that the presence of humidified aerosol particles in addition to the ice precipitation can explain the distribution and vertical profile of the observed depolarization ratios, although uncertainties related to the aerosol size distributions are substantial. These calculations show that humidified aerosol must be taken into account when interpreting lidar depolarization measurements for cloud and precipitation phase discrimination or ice habit classification, at least under conditions similar to those observed during SHEBA.

van Diedenhoven, Bastiaan; Fridlind, Ann M.; Ackerman, Andrew S.

2011-10-01

197

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

NASA Astrophysics Data System (ADS)

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.

1985-12-01

198

In situ Raman characterization of nanoparticle aerosols during flame synthesis  

NASA Astrophysics Data System (ADS)

Raman spectroscopy is applied to diagnose nanoparticle presence and characteristics in a gaseous flow field. Specifically, in situ monitoring of the Raman-active modes of TiO2 and Al2O3 nanoparticles in aerosol form is demonstrated in high-temperature flame environments. This technique serves as a sensitive and reliable way to characterize particle composition and crystallinity (e.g. anatase versus rutile) and delineate the phase conversion of nanoparticles as they evolve in the flow field. The effect of temperature on the solid-particle Raman spectra is investigated by seeding nanoparticles into a co-flow jet diffusion flame, where local gas-phase temperatures are correlated by shape-fitting the N2 vibrational Stokes Q-branch Raman spectra. Applying the technique to a flame synthesis environment, the results demonstrate that in situ Raman of as-formed nanoparticles can be readily applied to other gas-phase synthesis systems, especially as an on-line diagnostic.

Liu, X.; Smith, M. E.; Tse, S. D.

2010-09-01

199

Optical properties and vertical extension of aged ash layers over the Eastern Mediterranean as observed by Raman lidars during the Eyjafjallajökull eruption in May 2010  

NASA Astrophysics Data System (ADS)

The vertical extension and the optical properties of aged ash layers advected from the Eyjafjallajökull volcanic eruption over the Eastern Mediterranean (Greece and Turkey) are presented for the period May 10-21, 2010. Raman lidar observations performed at three stations of EARLINET (Athens, Thessaloniki and Istanbul), provided clear ash signatures within certain layers, although ash was sometimes mixed with mineral dust advected from the Saharan region. AERONET columnar measurements did not indicate the presence of ash over the area for that period, although they did for the dust particles. This was further investigated and confirmed by simulations of the ash trajectories by the FLEXPART model and the BSC-DREAM8b dust model. Good agreement was found between simulated and observed geometrical characteristics of the ash and dust layers, respectively. Ash particles were observed over the lidar stations after 6-7-days transport from the volcanic source at height ranges between approximately 1.5 and 6 km. Mean ash particle layer thickness ranged between 1.5 and 2.5 km and the corresponding aerosol optical depth (AOD) was of the order of 0.12-0.06 at 355 nm and of 0.04-0.05 at 532 nm. Inside the ash layers, the lidar ratios (LR) ranged between 55 and 67 sr at 355 nm and 76-89 sr at 532 nm, while the particle linear depolarization ratio ranged between 10 and 25%.

Papayannis, A.; Mamouri, R. E.; Amiridis, V.; Giannakaki, E.; Veselovskii, I.; Kokkalis, P.; Tsaknakis, G.; Balis, D.; Kristiansen, N. I.; Stohl, A.; Korenskiy, M.; Allakhverdiev, K.; Huseyinoglu, M. F.; Baykara, T.

2012-03-01

200

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

201

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

202

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

203

Micro pulse lidar observation of high altitude aerosol layers at Visakhapatnam located on the east coast of India  

Microsoft Academic Search

Aerosol back scatter profiles obtained using a micro pulse lidar at Visakhapatnam, a station located on the east coast of peninsular India show certain high altitude aerosol layers during the months of March\\/April 2005, 2006. Co-located aerosol optical depth measurements show an increase in AOD by 0.05 to 0.25 during the event when the layers were observed. The prevailing meteorology

K. Niranjan; B. L. Madhavan; V. Sreekanth

2007-01-01

204

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

205

Active Raman sounding of the earth's water vapor field  

Microsoft Academic Search

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

David M. Tratt; David N. Whiteman; Belay B. Demoz; Robert W. Farley; John E. Wessel

2005-01-01

206

Marine and biomass burning aerosols in the southern Indian Ocean: Retrieval of aerosol optical properties from shipborne lidar and Sun photometer measurements  

NASA Astrophysics Data System (ADS)

We document aerosol extinction properties in the southern Indian Ocean. A unique data set of shipborne measurements has been collected with a dual Rayleigh-Mie lidar aboard the research vessel Marion Dufresne during two campaigns: one around Madagascar during the Southern Hemisphere late summer and one close to the Kerguelen Islands during the biomass burning (BB) season. During this latter, a layer containing a mix of BB and marine aerosols extending up to ˜3 km above mean sea level (amsl) has been observed from [31°S, 69°E] to [24°S, 59°E]. Both vertical structure and aerosol optical properties have been retrieved from the inversion of the lidar signals. Sun photometer-derived aerosol optical thickness (AOT) at 355 nm is used to constrain the lidar inversion. We obtain a mean integrated value of backscatter-to-extinction ratio (BER) (extinction-to-backscatter ratio, or so-called lidar ratio, LR) of 0.039 ± 0.009 sr-1 (26 ± 6 sr) and 0.021 ± 0.006 sr-1 (48 ± 12 sr) for the marine aerosols layer, and for the mixing between BB and marine aerosols with an uncertainty of 0.009 sr-1 (6 sr) and 0.004 sr-1 (9 sr), respectively. Lidar calibration is used to inverse data without any simultaneous Sun photometer measurements (as nighttime data), and the temporal evolution of the optical properties and vertical extension of the BB aerosol plume is documented. The presence of BB aerosols is in agreement with Lagrangian model GIRAFE v3 (reGIonal ReAl time Fire plumEs) simulations, which show the South American and Southern African BB origin of the encountered aerosol layer.

Duflot, V.; Royer, P.; Chazette, P.; Baray, J.-L.; Courcoux, Y.; Delmas, R.

2011-09-01

207

Desert dust aerosol columnar properties over ocean and continental Africa from Lidar in-Space Technology Experiment (LITE) and Meteosat synergy  

Microsoft Academic Search

The new generation of spaceborne backscatter lidar systems, prefigured by the Lidar in-Space Technology Experiment (LITE) mission in September 1994, will give new insight on the vertical distribution of both aerosols and clouds in the atmosphere. This is especially of importance for aerosols over land, where retrievals from passive sensors are known to be more difficult because of the surface

S. Berthier; P. Chazette; P. Couvert; J. Pelon; F. Dulac; F. Thieuleux; C. Moulin; T. Pain

2006-01-01

208

Comparison of ambient aerosol extinction coefficients obtained from in-situ, MAX-DOAS and LIDAR measurements at a continental site (Cabauw)  

NASA Astrophysics Data System (ADS)

In the field, aerosol in-situ measurements are often performed under dry conditions (relative humidity RH<30-40%). Since ambient aerosol particles experience hygroscopic growth at enhanced RH, their microphysical and optical properties - especially the aerosol light scattering - are strongly dependent on RH. The knowledge of this RH effect is of eminent importance for climate forcing calculations or for the comparison of remote sensing with in-situ measurements. We will present results from a four-month campaign which took place in summer 2009 in Cabauw (Netherlands) and was part of the Cabauw Intercomparison Campaign of Nitrogen Dioxide measuring Instruments (CINDI). During this campaign different remote sensing and in-situ instruments were used to derive atmospheric gas species and aerosol properties. The aerosol scattering coefficient ?sp(?) was measured dry and at various, predefined RH conditions between 20 and 95% with a recently developed humidified nephelometer (WetNeph). The scattering enhancement factor f(RH,?) is the key parameter to describe the effect of RH on ?sp(?) and is defined as ?sp(?,RH) measured at a certain RH divided by the dry ?sp(?,RH=dry). The measurement of f(RH) together with the dry absorption measurement allows the determination of the actual extinction coefficient ?ep(?) at ambient RH. In addition, a wide range of further aerosol properties were measured in parallel. The measurements were used to characterize the effects of RH on the aerosol optical properties. A closure study showed the consistency of the aerosol in-situ measurements. Due to the large variability of airmass origin and aerosol composition a simple categorization could not be established. If f(RH) needs to be predicted, the chemical composition needs to be known. Four MAX-DOAS (multi-axis differential optical absorption spectroscopy) instruments retrieved vertical profiles of ?ep(?). The aerosol extinction corresponding to the lowest profile layer can be directly compared to the in-situ values, which were re-calculated to ambient RH. The comparison showed a good correlation of R2=0.59-0.78, but a factor of 1.4-2.76 higher extinction coefficients compared to the in-situ measured values. Best agreement is achieved for a few cases characterized by low aerosol optical depths and low planetary boundary layer heights. Differences showed to be dependent on the applied MAX-DOAS retrieval algorithm. The comparison of the in-situ data to a Raman lidar (light detection and ranging) showed much better agreement if the Raman retrieved profile was used to extrapolate the directly measured extinction coefficient to ground.

Zieger, P.; Weingartner, E.; Henzing, B.; Moerman, M.; de Leeuw, G.; Mikkilä, J.; Clémer, K.; van Roozendael, M.; Yilmaz, S.; Friess, U.; Irie, H.; Wagner, T.; Shaiganfar, R.; Beirle, S.; Apituley, A.; Wilson, K.; Baltensperger, U.

2010-12-01

209

Airborne High Spectral Resolution Lidar Aerosol Measurements during CalNex and CARES  

NASA Astrophysics Data System (ADS)

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 located mainly over Los Angeles; during the CARES deployment in June 2010, HSRL data were acquired during 23 science flights that were located mainly over Sacramento. The B200 flights were conducted so that the NOAA WP-3, NOAA Twin Otter, CIRPAS Twin Otter, and DOE G-1 aircraft often collected coincident data within the HSRL “curtains” thereby facilitating extensive intercomparisons and combined analyses. The HSRL data are used to characterize the vertical and horizontal distribution of aerosols, and to provide the vertical context for the airborne in situ measurements acquired from these other aircraft. In addition, aerosol intensive parameters derived from HSRL data are used to infer aerosol types and mixtures of those types. The fraction of aerosol optical thickness contributed by these types is also estimated from the HSRL data. Preliminary analyses of data acquired during CalNex shows cases where elevated layers of dust, likely transported from Asia, were located above urban aerosols. HSRL measurements are also used to determine Planetary Boundary Layer (PBL) height and investigate the variability of PBL height in these regions.

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

2010-12-01

210

Multidimensional Lidar, Sunphotometer and Aircraft Observations of Urban Aerosols during the DISCOVER-AQ Mission  

NASA Astrophysics Data System (ADS)

The Deriving Information on Surface Conditions from COlumn and VERtically Resolved Observations Relevant to Air Quality (DISCOVER-AQ) Mission is a five-year multisite experiment to better understand the relationship between satellite measured variables (columnar) with surface concentrations, required for air quality assessment and regulation. The first DISCOVER-AQ experiment was held in the Baltimore-Washington urban corridor during July 2011 and involved eleven lidars and two aircraft to provide the vertical profiles needed to close the vertical column with surface measures. In addition, over 40 sunphotometers were employed on a grid to add to the horizontal dimension during the DRAGON experiment, running concurrently. This paper is a preliminary look at a range of results from the experiment from very clear days, where the closure is relatively simple, to highly complex and varied aerosol regimes. Clearly important in the closure is the humidification of the aerosol that showed spatial variations in all three dimensions and may, in fact, dominate the relationship between aerosol optical depth and particle mass on a single day basis. Aerosol speciation analysis and in-situ microphysics from the aircraft is still being assessed and may explain scattering differences seen in depolarization of the aerosol and in aerosol layers confined to the PBL and aloft.

Hoff, R. M.; Berkoff, T.; Delgado, R.; Orozco, D.; McCann, K. J.; Crawford, J. H.; Anderson, B. E.; Hostetler, C. A.; Hair, J. W.; Ferrare, R. A.; Rogers, R.; Obland, M. D.; Holben, B. N.; Welton, E. J.

2011-12-01

211

A possible relationship of volcanic aerosol variations with El Nino Southern Oscillations - Lidar observations of volcanic aerosols in the atmosphere  

NASA Astrophysics Data System (ADS)

Estimations are made of atmospheric heating induced by aerosols falling through the upper troposphere during the season following the April 1982 El Chichon eruption. YAG lidars generated backscattering data at 1.06 and 0.53 micron. Half the giant particles are estimated to have fallen through the lower and middle latitude troposphere in the next three months. The particles would have undergone radiative cooling and aerosol heating by solar radiation absorption. The amount of settling particles is estimated to have been enough to have warmed the troposphere sufficiently to affect Hadley circulation. The circulation could have been weakened enough to lower the velocity of the trade winds and thus may have triggered the anomalous El Nino Southern Oscillation which occurred soon thereafter.

Hirono, M.; Shibata, T.; Fujiwara, M.

1985-04-01

212

Aerosol layers over the Pacific Ocean: Vertical distributions and optical properties as observed by multiwavelength airborne lidars  

Microsoft Academic Search

Scattering properties of tropospheric aerosol layers were observed with airborne lidars during the Global Backscatter Experiment (GLOBE) airborne campaigns covering a wide range of latitude and longitude over the Pacific Ocean. Lidar data at 0.532, 1.064, 1.54, and 9.25 ?m wavelengths are used to study the vertical profiles and optical properties of the marine boundary layer (MBL) as well as

Robert T. Menzies; David M. Tratt; James D. Spinhirne; Dennis L. Hlavka

2002-01-01

213

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

214

Lidar investigation of tropical nocturnal boundary layer aerosols and cloud macrophysics  

NASA Astrophysics Data System (ADS)

Observational evidence of two-way association between nocturnal boundary layer aerosols and cloud macrophysical properties over a tropical urban site 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 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, P. C. S.; Taraphdar, S.

2013-10-01

215

Satellite Lidar Data Assimilation For Improved Global Aerosol Forecasting: Lessons Learned From CALIOP, With an Eye Toward EarthCARE  

NASA Astrophysics Data System (ADS)

Active satellite-based aerosol profiling with lidar instruments represents a critical component of advanced global transport modeling and visibility forecasting applications. Parameterized aerosol source functions alone are limited in representing injection scenarios within a model. Two-dimensional variational (2D-VAR; x, y) assimilation of aerosol optical depth (AOD) from passive satellite radiance observations significantly improves the forecast system. However, this procedure does not compensate for any vertical redistribution of mass necessary. The expense of an inaccurate vertical profile of aerosol structure is corresponding errors downwind, since trajectory paths within successive model time steps typically diverge with height. Recent improvements to the Navy Aerosol Analysis and Prediction System (NAAPS) include a newly-designed 3D-VAR assimilation system based on NASA/CNES satellite-borne Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) aerosol backscatter profiles. NAAPS forecast skill improves with the benefit of 3D-VAR. However, it has proven considerably more challenging to implement this step than its 2D-VAR AOD counterpart. In this paper, we describe the process of assimilating satellite lidar measurements for aerosol applications, the development of model-friendly datasets, including a new NASA-disseminated product designed specifically for aerosol modeling applications, the importance of optimizing cross-track correlation in order to broaden the limited nadir-retrieved profile relative to the model grid and the potential for the near real-time/operational processing of ESA/JAXA Earth Clouds, Aerosol and Radiation Explorer (EarthCARE) high spectral resolution lidar datasets planned for late 2013. Lessons learned optimizing CALIOP datasets for modeling applications will not only improve performance in the short term, but ensure that developers are duly prepared for the coming EarthCARE data stream.

Campbell, J. R.; Reid, J. S.; Tackett, J. L.; Westphal, D. L.; Winker, D. M.; Zhang, J.

2010-12-01

216

Influence of biogenic pollen on optical properties of atmospheric aerosols observed by lidar over Gwangju, South Korea  

NASA Astrophysics Data System (ADS)

For the first time, optical properties of biogenic pollen, i.e., backscatter coefficients and depolarization ratios at 532 nm were retrieved by lidar observations. The extinction coefficient was derived with the assumption of possible values of the extinction-to-backscatter (lidar) ratio. We investigate the effect of the pollen on the optical properties of the observed atmospheric aerosols by comparing lidar and sun/sky radiometer measurements carried out at the lidar site. The observations were made with a depolarization lidar at the Gwangju Institute of Science & Technology (GIST) in Gwangju, Korea (35.13°N, 126.50°E) during an intensive observational period that lasted from 5 to 7 May 2009. The pollen concentration was measured with a Burkard trap sampler at the roof top of the Gwangju Bohoon hospital which is located 1 km away from the lidar site. During the observation period, high pollen concentrations of 1360, 2696, and 1952 m-3 day-1 were measured on 5, 6, and 7 May, respectively. A high lidar depolarization ratio caused by biogenic pollen was only detected during daytime within the planetary boundary layer which was at 1.5-2.0 km height above ground during the observational period. The contribution of biogenic pollen to the total backscatter coefficient was estimated from the particle depolarization ratio. Average hourly values of pollen optical depth were retrieved by integrating the pollen extinction coefficients. We find average values of 0.062 ± 0.037, 0.041 ± 0.028 and 0.067 ± 0.036 at 532 nm on 5, 6, and 7 May, respectively. The contribution of pollen optical depth to total aerosol optical depth was 2-34%. The sun/sky radiometer data show that biogenic pollen can affect optical properties of atmospheric aerosol by increasing aerosol optical depth and decreasing the Ångström exponent during daytime during the season of high pollen emission.

Noh, Young Min; Müller, Detlef; Lee, Hanlim; Choi, Tae Jin

2013-04-01

217

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

218

Temperature Variability in the Stratosphere Obtained from 7 years of Vibrational-Raman- lidar Measurements  

NASA Astrophysics Data System (ADS)

The Purple Crow Lidar (PCL) is a large power-aperture product monostatic laser radar located at the Delaware Observatory (42° 52' N, 81° 23' W, 225 m elevation above sea level) near the campus of The University of Western Ontario. It is capable of measuring temperature and wave parameters from 10 to 110 km altitude, as well as water vapor in the troposphere and stratosphere. We use upper tropospheric and stratospheric vibrational Raman N2 backscatter-derived temperatures to form a climatology for the years 1999 to 2007 from 10 to 30 km altitude. The lidar temperatures are validated using coincident radiosondes measurements from Detroit and Buffalo. The measured temperatures show good agreement with the radiosonde soundings. An agreement of ±1 K is found during summer months and ±2.5 K during the winter months, validating the calibration of the lidar to within the geophysical variability of the measurements. Comparison between the PCL measurements and atmospheric models shows the PCL measurements are 5 K or less colder than CIRA-86 below 25 km and 2.5 K warmer above during the summer months. Below 16 km the PCL measurements are 5 K or less colder than the MSIS-90 model, while above this region, the PCL agrees to about ±3.5 K or less. The temperature differences between the PCL measurements and the models are consistent with the differences between the atmospheric models and the Detroit and Buffalo radiosonde measurements. The temperature differences compared to the models are consistent with previous comparisons between other radiosondes and satellite data sets, confirming that these differences with the models are real. We will highlight nights which show significant variations from the long-term averages, and when possible, the evolution of the variations.

Iserhienrhien, B.; Sica, R. J.; Argall, P. S.

2009-05-01

219

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

220

Raman lidar measurements of water vapor and cirrus clouds during the passage of Hurricane Bonnie  

NASA Astrophysics Data System (ADS)

The NASA GSFC Scanning Raman Lidar (SRL) was stationed on Andros Island in the Bahamas during August-September 1998 as a part of the third Convection and Moisture Experiment (CAMEX 3) which focused on hurricane development and tracking. During the period August 21-24, Hurricane Bonnie passed near Andros Island and influenced the water vapor and cirrus cloud measurements acquired by the SRL. Two drying signatures related to the hurricane were recorded by the SRL and other sensors. Cirrus cloud optical depths (at 351 nm) were also measured during this period. Optical depth values ranged from less than 0.01 to 1.5. The influence of multiple scattering on these optical depth measurements was studied. A correction technique is presented which minimizes the influences of multiple scattering and derives information about cirrus cloud optical and physical properties. The UV/IR cirrus cloud optical depth ratio was estimated on the basis of a comparison of lidar and GOES 8 measurements. Simple radiative transfer model calculations compared with GOES satellite brightness temperatures indicate that satellite radiances are significantly affected by the presence of cirrus clouds if IR optical depths are ˜0.005 or greater. Using the International Satellite Cloud Climatology Project (ISCCP) detection threshold for cirrus clouds on the GOES data presented here, a high bias of up to 40% was found in the GOES precipitable water retrieval.

Whiteman, D. N.; Evans, K. D.; Demoz, B.; Starr, D. O'c.; Eloranta, E. W.; Tobin, D.; Feltz, W.; Jedlovec, G. J.; Gutman, S. I.; Schwemmer, G. K.; Cadirola, M.; Melfi, S. H.; Schmidlin, F. J.

2001-03-01

221

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 at 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

222

Parameterization of Stratospheric Aerosol Physical Properties on the Basis of Nd:YAG Lidar Observations.  

PubMed

An extension to the 355- and 1064-nm wavelengths of a numerical optical model originally developed at 532 nm is presented. The resulting parameterization allows estimates of stratospheric aerosol surface area, volume, and extinction-to-backscatter ratio from lidar measurements obtained at one of the two Nd:YAG laser wavelengths. Functional relationships that link single-wavelength backscatter to each of the physical variables are provided for sulfate aerosol types ranging from background to heavy volcanic under environmental conditions representative of the global lower stratosphere. The behavior of the functional relationships at the three Nd:YAG wavelengths is compared. Relative errors of model estimates range between 10% and 50%, depending on wavelength and backscatter cross sections. These values are comparable with the ones that characterize in situ particle counters. The inference of particle effective radius and the application of the method to the interpretation of supercooled polar stratospheric cloud observations are discussed. PMID:18285928

Gobbi, G P

1998-07-20

223

Vertical distribution of aerosols over an urban continental site in India inferred using a micro pulse lidar  

NASA Astrophysics Data System (ADS)

Knowledge of the vertical distribution of aerosols in the atmosphere is important in estimating its radiative forcing. While aircraft based measurements over two locations in India have provided valuable information, the temporal coverage of measurements was limited. In this paper, we examine the vertical distribution of aerosols over a continental, urban location, Bangalore in southern India, using a micro pulse lidar (MPL) operated for about two years (2004 and 2005), and infer the effects of the boundary layer dynamics. Early morning hours are characterized by a shallow aerosol layer, a few hundred meters thick. As day advances, the strong convective eddies are seen to transport the aerosols vertically up to more than 1500 m. Seasonal changes in the aerosol vertical structure, contribution of the boundary layer aerosols to the column optical depth as well as the frequency of occurrence of clouds within aerosol layer are examined.

Satheesh, S. K.; Vinoj, V.; Moorthy, K. Krishna

2006-10-01

224

Vertical distribution of the aerosol optical properties on multi-annual scale observed by lidar at L'Aquila, Italy.  

NASA Astrophysics Data System (ADS)

The CETEMPS lidar (42.38N, 13.32E, 683m a.s.l.) is, since May 2000, fully operational for the measurement of the vertical profile of the aerosol extinction and backscatter coefficients, of the water vapour concentration, in PBL and in the lower troposphere. The source of the system is an excimer laser (351nm), the typical nighttime measurement covers a period of 2-3 hours, the system has reduced performances during daytime. In climatological mode, on average, two sessions of measurements per week are usually performed. In the case of special events (i.e., Saharan dust outbreaks, forest fires, etc.) or along intensive campaign of validation and comparison versus other instruments, the rate of observations increases. The geophysical products of the CETEMPS lidar consist in the vertical profile of the extinction and backscatter coefficients at 351nm, and the water vapour mixing ratio. The algorithms used to evaluate the lidar measurements and to quantify their reliability have been tested within the EARLINET (http://www.earlinet.org/) activities that are devoted to the data quality assurance. These EARLINET tasks have also included several hardware tests. In a standard/typical measurement session, the CETEMPS lidar has the following performances, for the aerosol optical properties: - 351nm backscatter coefficient - temporal resolution of 30 minutes, indetermination between 5% and 15% , altitude resolution between 60m and 600m; - simultaneous 351nm extinction coefficient - temporal resolution of 30 minutes, indetermination between 10% and 20% , altitude resolution between 60m and 600m;. Concerning the water vapour profile, the lidar data inversion is based on standard algorithms: - the water vapour mixing ratio is obtained with a temporal resolution of 10minutes, errors ranging between 5% and 20% (including some systematics coming from calibration procedures), vertical resolution between 30 and 100m. The liquid water lidar channel of the CETEMPS lidar is sensitive to the liquid water content, and it provides information in presence of clouds or wet aerosols. With dedicated calibration procedures, it is possible to evaluate the cloud liquid water content. The CETEMPS lidar, within EARLINET, contributes to the constitution of a database for investigating the aerosol climatology on continental scale. We will report analysis (about 7 years of observations at the site of L'Aquila) of the aerosol optical properties: the seasonal behavior and the monthly means variations of the PBL aerosol optical depth (AOD), and of the PBL height. The possible correlation between the aerosol optical properties and the water vapour content is also discussed.

Rizi, Vincenzo; Iarlori, Marco

2010-05-01

225

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

226

A lidar technique for adjusting aerosol model number densities close to the ocean surface  

NASA Astrophysics Data System (ADS)

With the Navy's interest in FLIR detectors at submarine periscope heights, it is important to get more detailed information on the atmospheric characteristics at FLIR wavelengths (3 to 5 and 8 to 12 microns) in the first few meters above the ocean. This information is particularly important for predicting the performance of electro-optical systems operating against skimmer-type missiles approaching a ship or submarine from beyond the horizon. A technique is introduced by which the total number density of the LOWTRAN 7 Navy Aerosol Model (NAM) (the kernel for the Naval Oceanic Vertical Aerosol Model) is adjusted to represent existing conditions close to the ocean surface. Measurements of bulk meteorological parameters at a reference height above the ocean surface are used to generate stability dependent logarithmic profiles of temperature and relative humidity. These profiles are used with the aerosol model to determine aerosol extinction and backscatter coefficient variations close to the ocean surface. Using the single-scatter lidar (light detection and ranging) equation, these parameters are then used to calculate a range compensated power, S(R), returned from scattering volumes at different heights in the modeled atmosphere. An iterative method is used by which the calculated S(R) values are adjusted to agree with the corresponding measured values obtained with a lidar operating at 1.06 microns and directed at the ocean over a slant path from an altitude of 10 meters. Examples of extinction coefficient variations with height above the ocean surface, calculated using the original and adjusted size distribution for different surface wind speed conditions and air-mass characteristics.

Paulson, M. R.; Hughes, H. G.

1990-12-01

227

Optical properties of aerosols obtained from airborne lidar and several in-situ instruments during RACE  

NASA Astrophysics Data System (ADS)

Two aircraft, the National Research Council of Canada (NRCC) Convair 580 (CV580) and NRCC DHC-6 Twin Otter, along with the Yarmouth and Digby Ferries, a ground site near Yarmouth and coordination with satellite overpasses (AVHRR and LANDSAT) provided an exceptionally well rounded compliment of observing platforms to meet the project objectives for the radiation, aerosols and cloud experiment (RACE) (refer to http://www.on.doe.ca/armp/RACE/RACE.html for a complete list of instrumentation and investigators involved). The general flight plans involved upwind measurements of a selected target by the CV580 lidar, followed by coincident flights allowing the Twin Otter to perform in-situ measurements while the Convair used a variety of remote sensors from above. The CV580 then descended to perform in-situ measurements including size segregated samples through the use of a micro-orifice uniform deposit impactor (MOUDI). This paper focuses on the airborne lidar results during RACE and in particular introduces two case studies comparing the lidar with a MOUDI impactor and ASASP particle probe using Mie theory.

Strawbridge, Kevin B.; Li, Shao-Meng

1997-05-01

228

Aerosol vertical distribution in dust outflow over the Atlantic: Comparisons between GEOS-Chem and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO)  

Microsoft Academic Search

Vertically resolved attenuated backscatter from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) mission and aerosol optical thickness (AOT) from the Moderate-resolution Imaging Spectroradiometer (MODIS) are used to characterize the Saharan dust outflow over the Atlantic and to evaluate results from a global chemical and transport model (GEOS-Chem). We first document two events of dust plume transport from the

Sylvia Generoso; Isabelle Bey; Mathieu Labonne; François-Marie Bréon

2008-01-01

229

Lidar observations of stratospheric ozone and aerosol above the Canadian High Arctic during the 1994–95 winter  

Microsoft Academic Search

This letter reports on lidar observations of arctic stratospheric ozone and aerosol made from late December 1994 to mid-March 1995. These observations were conducted at Eureka (80øN,86.42øW) in the dian arctic. Based on NMC potential vorticity data and aerosol observations, the lower stratosphere over Eu- reka was seen to be clearly within the Polar Vortex for most of the observation

D. P. Donovan; J. C. Bird; J. A. Whiteway; T. J. Duck; S. R. Pal; A. I. Carswell

1995-01-01

230

Raman characterization and chemical imaging of biocolloidal self-assemblies, drug delivery systems, and pulmonary inhalation aerosols: A review  

Microsoft Academic Search

This review presents an introduction to Raman scattering and describes the various Raman spectroscopy, Raman microscopy, and\\u000a chemical imaging techniques that have demonstrated utility in biocolloidal self-assemblies, pharmaceutical drug delivery systems,\\u000a and pulmonary research applications. Recent Raman applications to pharmaceutical aerosols in the context of pulmonary inhalation\\u000a aerosol delivery are discussed. The “molecular fingerprint” insight that Raman applications provide includes

Heidi M. Mansour; Anthony J. Hickey

2007-01-01

231

Considerable Effect of Stratospheric Aerosol on Lidar-Detected Ozone Profile and a Three-Wavelength Inversion Technique for Both Ozone and Aerosol.  

National Technical Information Service (NTIS)

As far as the Differential Absorption Lidar (DIAL) technique is concerned, it is important that the off-line wavelength is close to the on-line wavelength in order to avoid a messy computation of the atmospheric aerosol scattering. However, the two wavele...

J. Qiu

1992-01-01

232

Aerosols and transport in the tropical UTLS as deduced from CALIPSO lidar observations  

NASA Astrophysics Data System (ADS)

This work deals with the study of aerosols in the tropical UTLS and transport processes responsible for their time evolution from the first two years observations of the CALIOP lidar carried on the French-US CALIPSO satellite launched in May 2006. Stratospheric aerosols retrieval algorithms developed have shown: a) the impact of medium-scale volcanic eruptions which represent an important source of aerosols in the stratosphere, ignored until now; b) the decoupling of the mid- and lower stratosphere at 20km separated by a region of zero vertical velocity, surmounted by the slow ascent of the Brewer-Dobson circulation modulated by the Quasi-Biennal Oscillation; c) the injection of clean air until 20km in the equatorial region during the boreal winter, likely washed out in the troposphere and rapidly transport in the most convective regions located above the tropical continents of the south hemisphere. d) the occurrence of aerosols between 15 and 18km above West Africa and Asia during their respective monsoon season, which could be small mineral dust lifted by convection from Sahara and Gobi deserts.

Vernier, Jean-Paul; Pommereau, Jean-Pierre; Garnier, Anne; Pelon, Jacques; Thomason, Larry; Pitts, Mike

2010-05-01

233

Lidar observations of Kasatochi volcano aerosols in the troposphere and stratosphere  

NASA Astrophysics Data System (ADS)

The eruption of Kasatochi volcano on 7-8 August 2008 injected material into the troposphere and lower stratosphere of the northern midlatitudes during a period of low stratospheric aerosol background concentrations. Aerosols from the volcanic plume were detected with a lidar in Halifax, Nova Scotia (44.64°N, 63.59°W) 1 week after the eruption and for the next 4 months thereafter. The volcanic origin of the plume is established using the FLEXPART Lagrangian particle transport model for both the stratosphere and troposphere. The stratospheric plume descended 47.1 ± 2.8 m/d on average as it dispersed, corresponding to a cooling rate of 0.60 ± 0.07 K/d. The descent rate was the same for the tropopause (within statistical uncertainties). The top of the plume remained steady at about 18 km altitude and was likely sustained by vertical eddy diffusion from large-scale horizontal mixing. The lower boundary of the plume descended with the tropopause. The integrated aerosol backscatter between 15 and 19 km altitude was relatively constant at about 8 × 10-5 sr-1 for 532 nm wavelength. Observations and modeling of Kasatochi aerosols in the middle and lower troposphere indicate a possible ground impact. The volcanic contribution to surface PM2.5 did not exceed 5 ?g/m3 at the measurement site.

Bitar, L.; Duck, T. J.; Kristiansen, N. I.; Stohl, A.; Beauchamp, S.

2010-01-01

234

Micro pulse Lidar Observations of aerosol profiles over urban region of Hyderabad - Influence of Agricultural Crop Residue Burning  

NASA Astrophysics Data System (ADS)

Aerosols from biomass burning modify cloud microphysical properties and cloud lifetime through the so-called "indirect effect." In the absence of wet scavenging processes, aerosols stay suspended for days to weeks and can be transported to considerable distances. Biomass burning from forest regions and agriculture crop residues can emit substantial amounts of particulate matter and other pollutants into the atmosphere. Results from the Southern African Regional Science Initiative (SAFARI) 2000 dry season field campaign often revealed the presence of an elevated biomass-burning aerosol layer above a semi-permanent stratiform cloud deck off the southern African coasts. An inventory of forest, grassland and agricultural burning is important for studies related to global change. This study provides an account of the agriculture crop residue burning over Indian region and its influence on the columnar aerosol loading over urban region of Hyderabad. Boundary Layer Lidar System fabricated by NARL was used to study the variations in vertical profiles of aerosols during October, 2007 at Hyderabad. The variations in aerosol vertical profiles from Lidar data correlated with sunphotometer observations on aerosol optical depth, black carbon mass concentrations and single scattering albedo estimated from PREDE skyradiomter. The analysis of satellite data sets suggested agricultural crop residue burning towards north of the observations site. The LIDAR profiles revealed the existence of important quantities of aerosols at altitudes between 1200 and 1800m over the city. Three dimensional 120-hours air mass back-trajectory analysis showed that the aerosols detected at the higher altitudes might have originated from agriculture crop residue burning activities taking place at the northern regions. Conjunctive analysis of satellite data together with ground observations provides a means for understanding source regions of aerosols. The results are discussed in the paper.

Kharol, Shailesh Kumar; Badarinath, Kvs; Sharma, Anu Rani; Mahalakshmi, D. V.; K., Sujatha; Yellapragada, Bhavani Kumar

235

Optical properties of tropospheric aerosols determined by lidar and spectrophotometric measurements (Photochemical Activity and Solar Ultraviolet Radiation campaign).  

PubMed

We present the results of the aerosol measurements carried out over the Aegean Sea during the Photochemical Activity and Solar Ultraviolet Radiation campaign held in Greece during June 1996. Simultaneous observations performed with a lidar and a double-monochromator spectrophotometer allowed us to retrieve the optical depth, the Angström coefficient, and the backscatter-to-extinction ratio. The Sun photometric data can be used to improve quantitative aerosol measurements by lidar in the Planetary Boundary Layer. Systematic errors could arise otherwise, because the value of the backscatter-to-extinction ratio has to be supplied. Instead this ratio can be retrieved experimentally by use of an iterative solution of the lidar equation. PMID:18259559

Marenco, F; Santacesaria, V; Bais, A F; Balis, D; di Sarra, A; Papayannis, A; Zerefos, C

1997-09-20

236

Evolution of the Pinatubo volcanic aerosol column above Pasadena, California observed with a mid-infrared backscatter lidar  

Microsoft Academic Search

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

David M. Tratt; Robert T. Menzies

1995-01-01

237

Comparison of upper tropospheric water vapor from GOES, Raman lidar, and Cross-chain Loran Atmospheric Sounding System measurements  

Microsoft Academic Search

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).

B. J. Soden; S. A. Ackerman; S. H. Melfi; R. A. Ferrare

1994-01-01

238

Water Vapor and Cloud Detection Validation for Aqua Using Raman Lidars and AERI and the AWEX-G Validation Experiment  

Microsoft Academic Search

The early work in this investigation focused on the use of Raman lidar, ra- diosonde and AERI measurements for AIRS validation measurements as was reported in last year's annual report. That report revealed at times large unex- plained differences in various validation datasets being used forAIRS valida- tion. Because of this, the AIRS Water Vapor Experiment-Ground (AWEX-G) was proposed, funded

David Whiteman; Belay Demoz; Frank Schmidlin; Zhien Wang; Igor Veselovskii; Wallace McMillan; Ray Hoff; Felicita Russo; Scott Hannon; Larry Miloshevich; Barry Lesht; Gary Jedlovec; Madison WI; Martin Cadirola

239

Characterization of gas-aerosol interaction kinetics using morphology dependent stimulated Raman scattering  

SciTech Connect

A research program on the influence of aerosol surface structure on the kinetics of gas-aerosol interactions is proposed. The experiments involve measuring changes in gas phase chemical reaction rates as a function of exposure to a specific aerosol. Aerosols with differing surface properties will be generated by changing the composition and/or temperature of the material making up the aerosol. Kinetic data generated can be used directly in atmospheric modelling calculations. The surface structure of the aerosol will be measured, both before and after reaction, using morphology-dependent enhancement of simulated Raman scattering (MDSRS). Information about the detailed dynamics of gas-aerosol interactions can be obtained by correlating the change in the reaction rate with change in surface structure and by monitoring the change in aerosol surface structure during the course of the reaction. Studies will focus on the condensation and oxidation of sulfur species (sulfur dioxide and dimethyl sulfide) on water aerosols.

Aker, P.M.

1992-01-01

240

Characterization of gas-aerosol interaction kinetics using morphology dependent stimulated Raman scattering. Final technical report  

SciTech Connect

A research program on the influence of aerosol surface structure on the kinetics of gas-aerosol interactions is proposed. The experiments involve measuring changes in gas phase chemical reaction rates as a function of exposure to a specific aerosol. Aerosols with differing surface properties will be generated by changing the composition and/or temperature of the material making up the aerosol. Kinetic data generated can be used directly in atmospheric modelling calculations. The surface structure of the aerosol will be measured, both before and after reaction, using morphology-dependent enhancement of simulated Raman scattering (MDSRS). Information about the detailed dynamics of gas-aerosol interactions can be obtained by correlating the change in the reaction rate with change in surface structure and by monitoring the change in aerosol surface structure during the course of the reaction. Studies will focus on the condensation and oxidation of sulfur species (sulfur dioxide and dimethyl sulfide) on water aerosols.

Aker, P.M.

1992-12-31

241

Ground-based lidar measurements from Ny-Ålesund during ASTAR 2007: a statistical overview  

Microsoft Academic Search

During the Arctic Study of Tropospheric Aerosol, Clouds and Radiation (ASTAR) in March and April 2007, measurements obtained at the AWIPEV Research station in Ny-Ålesund, Spitsbergen (operated by the Alfred-Wegener-Institute for Polar and Marine Research and the Institut polaire français Paul-Emile Victor), supported the airborne campaign. This included Lidar data from the Koldewey Aerosol Raman Lidar (KARL) and the Micro

A. Hoffmann; C. Ritter; M. Stock; M. Shiobara; A. Lampert; M. Maturilli; T. Orgis; R. Neuber; A. Herber

2009-01-01

242

Interpreting aerosol lidar profiles to better estimate surface PM2.5 for columnar AOD measurements  

NASA Astrophysics Data System (ADS)

Satellite aerosol optical depth (AOD) products have been used to estimate surface PM2.5 in different parts of the world. However, some revealed good but some relatively poorer relationship between AOD and PM2.5. The increasingly available lidar-based aerosol extinction profiles provide insights into the boundary layer as well as residual above it. Here we report a study in Taiwan using four-year (2006-2009) MPLNet data to characterize aerosol vertical distribution. We derived haze layer height (HLH) from MPLNet aerosol extinction profiles and classified profile differences by mean PBL extinction (MPE) and near-surface extinction (NSE). The former represents the mean extinction within boundary layer and the latter the closest extinction to surface. The comparison of MPE versus NSE leads to three distinct classifications of aerosol profiles to help interpret the relationship between AOD and PM2.5. The approximation of normalizing AODAERONET by HLH closely follows MPE in correlating with PM2.5 (?0.8 with respect to season or ?0.85 with respect to profile classification). The correlation resulted from AODMODIS/HLH is systematically lower than that derived by AODAERONET/HLH. PM2.5 values are overall better estimated by profile classification than those derived by season. Better performance of PM2.5 is obtained with the approximation (i.e., normalizing AOD by HLH) than that using AOD only. The performance metrics used in quantifying the relationship reveal improvements in uncertainty by 2.9 ?g m-3 (or 20%) with AODAERONET/HLH and 2.3 ?g m-3 (or 15%) with AODMODIS/HLH in comparison to using AOD only.

Chu, D. Allen; Tsai, Tzu-Chin; Chen, Jen-Ping; Chang, Shuenn-Chin; Jeng, Yung-Jyh; Chiang, Wei-Li; Lin, Neng-Hui

2013-11-01

243

Study on optical and microphysical properties of mixed aerosols from lidar during the EMEP 2012 summer campaign at 45oN 26oE  

NASA Astrophysics Data System (ADS)

Aerosols optical and chemical properties in the upper layers of the atmosphere and near ground are variable, as function of the different mixtures of aerosol components resulting from their origin and transport over polluted areas. Due to a complex dynamics of air masses, the Romanian atmosphere has strong influences from dust and biomass-burning transported from South, West or East Europe. The dominant transport, and consequently the dominant aerosol type, depends on the season. As a result of the transport distance from the source and depending on the chemical and physical characteristics of the particles, tropospheric aerosols detected at Magurele, Romania, show different optical and microphysical properties than at the originating source. The differences are caused by the mixing with local particles, and also by the ageing processes and hygroscopic growth during the transport. This paper presents a statistical analysis of tropospheric aerosol optical properties during the EMEP (European Monitoring and Evaluation Programme) summer campaign (08 June - 17 July 2012), as retrieved from multiwavelength Raman and depolarization lidar data. Three elastic (1064, 532 and 355 nm), two Raman (607 and 387 nm) and one depolarization channel (532 nm parallel / 532 nm cross) are used to independently retrieve the backscatter coefficient, extinction coefficient and linear particle depolarization ratio of aerosols between 0.8 and 10 km altitude. Intensive optical parameters (Angstrom exponent, color ratios and color indexes) and microphysical parameters (effective radius, complex refractive index) from multiwavelength optical data inversion of the layer mean values are obtained. During the campaign, aerosol profiles were measured daily around sunset, following EARLINET standards. An intensive 3-days continuous measurements exercise was also performed. Layers were generally present above 2 km and bellow 6 km altitude, but descent of air masses from the free troposphere to the ground was also possible in favorable meteorological conditions. Long-range transport of mineral dust originating from Sahara region was dominating the 3 - 5 km layers for the entire period. The presence of non-spherical particles was assessed based on high particle depolarization values measured by the lidar and confirmed by the HYSPLIT backtrajectories. Only 7 out of the 22 layers carrying mineral dust particles were found to have optical properties of pure Saharan dust. The mixing of Saharan dust with continental polluted aerosols results in a modification of both intensive (AE, SSA) and extensive (AOD) optical properties. Three cases of biomass burning were also observed and analyzed: 8, 14 and 24 June, 2012. Microphysical inversion was performed for the lofted layers, and results were compared to the measurements at ground, using a C-ToF Aerosol Mass Spectrometer. The spectrometer provides real-time size resolved composition analysis of particulate matter, with 0.002 ?g/m3 detection limit and mass range up to 800 m/z. Mixing with local aerosols but also changes in the chemical properties due to ageing processes and hygroscopic growth were found to strongly influence the optical and microphysical properties of long-range transported biomass burning particles.

Talianu, Camelia; Nicolae, Doina; Belegante, Livio; Marmureanu, Luminita

2013-04-01

244

Evidence of seasonally dependent stratosphere-troposphere exchange and purging of lower stratospheric aerosol from a multiyear lidar data set  

SciTech Connect

Tropospheric and lower stratospheric aerosol backscatter data obtained from a calibrated backscatter lidar at Pasadena, California (34 deg N latitude) over the 1984-1993 period clearly indicate tightly coupled aerosol optical properties in the upper troposphere and lower stratosphere in the winter and early spring, due to the active midlatitude stratospheric-tropospheric (ST) exchange processes occurring at this time of year. Lidar data indicate that during pre-Pinaturbo background conditions, the subsequent purging of the aerosol in the upper troposphere caused a significant reduction in the aerosol content throughout the 8 - 18 km altitude region in the early spring period. The post-Pinatubo evidence of intense exchange in the winter and early spring is a significant increase in the upper tropospheric aerosol content, such that the backscatter levels reach values nearly equivalent to the enhanced backscatter levels existing in the lower stratosphere. The calculated stratospheric mass extrusion rate is consistent with a 45-day lifetime of lower stratospheric aerosol during this part of the year, which implies that midlatitude ST exchange is a significant sink for stratospheric aerosol.

Menzies, R.T.; Tratt, D.M. [Jet Propulsion Lab., California Inst. of Tech., Pasadena, CA (United States)

1995-02-01

245

New approach for aerosol profiling with a lidar onboard an ultralight aircraft: application to the African Monsoon Multidisciplinary Analysis.  

PubMed

A new airborne instrumental payload has been designed for an ultralight aircraft to determine the vertical profile of aerosol optical properties. It is based on Lidar Aérosols UltraViolet Aéroporté (LAUVA), a compact backscattering lidar system emitting at the wavelength of 355 nm. We operated this airborne configuration in the Sahel from the city of Niamey (Niger) during the first campaign of the African Monsoon Multidisciplinary Analysis (AMMA) in January-February 2006, when aerosols from both soil dust and savannah fires cause large visibility reductions. We take advantage of the lidar capability of pointing in different directions for retrieving the vertical profile of the aerosol backscatter to extinction ratio (BER). A synergy with a scatterometer (880 nm) and a ground-based sunphotometer allows us to further determine the vertical profile of Angström exponent (a). We identify three types of aerosol layers up to about 5 km below the free troposphere, dominated by biomass burning (BB) particles, mineral dust (D) particles, and a mixing between BB and D particles, respectively, associated with BER (a) values close to 0.008 sr(-1) (1.5), 0.025 sr(-1) (0), and 0.015 sr(-1) (0.4-1). PMID:18200860

Chazette, Patrick; Sanak, Joseph; Dulac, François

2007-12-15

246

Validation of CALIPSO space-borne-derived attenuated backscatter coefficient profiles using a ground-based lidar in Athens, Greece  

Microsoft Academic Search

We present initial aerosol validation results of the space-borne lidar CALIOP -onboard the CALIPSO satellite- Level 1 attenuated backscatter coefficient profiles, using coincident observations performed with a ground-based lidar in Athens, Greece (37.9° N, 23.6° E). A multi-wavelength ground-based backscatter\\/Raman lidar system is operating since 2000 at the National Technical University of Athens (NTUA) in the framework of the European

R. E. Mamouri; V. Amiridis; A. Papayannis; E. Giannakaki; G. Tsaknakis; D. S. Balis

2009-01-01

247

Clear and cloudy sky investigations using Raman lidar and airborne interferometric measures from the European AQUA Thermodynamic Experiment  

NASA Astrophysics Data System (ADS)

A dataset of ground, airborne and satellite data was measured during the comprehensive 2004 EAQUATE (European AQUA Thermodynamic Experiment) Italian campaign. We have used ground based and airborne data to evaluate the consistency of Raman lidar temperature and humidity profiles with NAST-I (The National Polar-orbiting Operational Environmental Satellite System Airborne Sounder Testbed-Interferometer) spectral radiance measurements in clear conditions, and the consistency of total cloud optical depth measured by the Raman lidar with the same quantity retrieved from NAST-I measurements. Lidar measurement of temperature and humidity profiles can resolve short time changes in mixing ratio due to its high time resolution. Brightness temperature simulations of clear sky, performed using lidar-derived profiles, are within 1 K difference with respect to data when averages over 25 cm -1 and emission from layers below 7 km are considered. High spectral resolution simulations agree with NAST-I measurements with a mean percentage difference less than 0.5% in the whole ?2 water vapour band. The simulations in cloudy conditions are based on crystal properties obtained assuming either an appropriate mixture of crystal habits (that for the first time is tested against high spectral resolution measurements) or pristine solid columns. Lidar-derived cloud base and top altitudes and lidar temperature and humidity profiles are exploited, for the first time, as inputs in a recently developed infrared cloud properties retrieval procedure. Total cloud optical depths, retrieved from 800 to 980 cm -1 NAST-I radiances, have values that, when converted to short-wave wavelengths, are in the range 0.05-2.2 and agree with lidar measurements to within experimental errors. A closer agreement is obtained with the mixture of habits. Simulated high resolution brightness temperatures based on retrieved cloud parameters (optical depths and effective dimensions) are compared with measured values in all the atmospheric windows covered by the NAST-I sensor. The agreement obtained in the 800-980 cm -1 interval is generally better for the mixture of habits, but solid columns produce smaller residuals in the 2000-2150 and 2400-2600 cm -1 spectral intervals. Uncertainties related to the surface properties (i.e. skin temperature) are recognized to be the main sources of error in the infrared retrieval of cloud properties and affect the comparison between forward simulations and NAST-I data in all the infrared window bands not used for the inverse problem.

Tiziano, Maestri; Paolo, Di Girolamo; Donato, Summa; Rolando, Rizzi

2010-07-01

248

Preliminary results on a study of stratospheric aerosol loading by means of lidar analysis of long- and short-time fluctuations  

NASA Astrophysics Data System (ADS)

Lidar stratospheric aerosol measurements carried out since the eruption of the Mexican volcano El Chichon in April 1982 are reported and discussed. The improved lidar system used consists of a Nd-Yag laser transmitter formed by an oscillator and an amplifier. This system is described along with the measurements, showing lidar profiles, scattering ratio as a function of height, integrated back-scattering, and back-scattering coefficient as a function of height. The short-time fluctuations in lidar signatures are analyzed to obtain information on stratospheric air turbulence and on the possible presence of gravity waves.

Stefanutti, L.; Morandi, M.; Castagnoli, F.; Radicati, B.

1985-12-01

249

GOES Aerosol/Smoke Product (GASP) Over North America: Comparisons to AERONET, MODIS and LIDAR Observations  

NASA Astrophysics Data System (ADS)

We present the GOES Aerosol/Smoke Product (GASP) and comparisons to AERONET and MODIS observations over North America. GASP is currently available in near-realtime from NOAA's National Environmental Satellite Data and Information Service (http://www.ssd.noaa.gov/PS/FIRE/GASP/gasp.html) at 30 minute intervals during daylight hours. We find good agreement between the GASP AOD and AEROMET AOD over the northeastern US and Canada with a mean correlation of 0.75 and rms difference of 0.15 based on comparisons at 10 AERONET sites. GASP is also in good agreement with MODIS AOD over the northeastern US during summertime, with an average correlation of 0.8 However, GASP has the added advantage of high temporal resolution, making it useful for tracking and analyzing particulate pollution events resulting from dust, smoke, or industrial aerosols. We also present the GASP AOD and comparisons to lidar observations and ground based fine particulate matter concentrations during the unusual haze episode in the winter 2005 from January 28 to February 10th, and during the hazy period affecting the eastern, midatlantic, and midwestern US between August 1st and August 14th, 2005.

Prados, A. I.; Kondragunta, S.; Ciren, P.; Hoff, R.; McCann, K.; Rogers, R.

2006-05-01

250

Calibration method for the lidar-observed stratospheric depolarization ratio in the presence of liquid aerosol particles.  

PubMed

A fine calibration of the depolarization ratio is required for a detailed interpretation of lidar-observed polar stratospheric clouds. We propose a procedure for analyzing data by using atmospheric depolarization lidar. The method is based on a plot of deltaT versus (1 - RT(-1)), where deltaT is the total depolarization ratio and RT is the total backscattering ratio. Assuming that there are only spherical particles in some altitude ranges of the lidar data, the characteristics of the plot of deltaT versus (1 - RT(-1)) lead to a simple but effective calibration method for deltaT. Additionally, the depolarization of air molecules deltam can be determined in the process of deltaT calibration. We compared determined values with theoretically calculated values for the depolarization of air to test the proposed method. The deltam value was calculated from the lidar data acquired at Ny-Alesund (79 degrees N, 12 degrees E), Svalbard in winter 1994-1995. When only sulfate aerosols were present on 24 December 1994, deltam was 0.46 +/- 0.35%. When the particles consisted of sulfate aerosols and spherical particles of polar stratospheric clouds on 4 January 1995, deltam was 0.45 +/- 0.07%. Both deltam values were in good agreement with the theoretically calculated value, 0.50 +/- 0.03%. PMID:18364966

Adachi, H; Shibata, T; Iwasaka, Y; Fujiwara, M

2001-12-20

251

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

252

Statistics of aerosol extinction coefficient profiles and optical depth using lidar measurement over Lanzhou, China since 2005-2008  

NASA Astrophysics Data System (ADS)

The aerosol extinction coefficient profiles and optical depth over Lanzhou in China were observed under no precipitation and dust free condition using the micropulse lidar CE370-2 from September 2005 to July 2008. The statistics of the variations of monthly average aerosol optical depth (AOD) and daily average AOD, frequency distribution of daily average AOD, and the seasonal variation of aerosol vertical distribution were analyzed based on the observation data. The results showed that the daily average AOD of Main Observatory and City Observatory was 87.8% and 78.2% ranged below 0.4 respectively with similar frequency distribution patterns. The AOD in autumn and winter were larger than that in spring and summer, and AOD in suburb was in certain extent smaller than that in city of Lanzhou. Aerosol existed in the layer below 4km, and its extinction coefficient decreased with increasing of height.

Cao, X.; Wang, Z.; Tian, P.; Wang, J.; Zhang, L.; Quan, X.

2013-06-01

253

Comparing simultaneous stratospheric aerosol and ozone lidar measurements with SAGE II data after the Mount Pinatubo eruption  

SciTech Connect

Stratospheric aerosol and ozone profiles obtained simultaneously from the lidar station at the University of L`Aquila (42.35{degrees}N, 13.33{degrees}E, 683m 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) II 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 II 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. 28 refs., 2 figs.

Yue, G.K.; Poole, L.R.; McCormick, M.P. [Langley Research Center, Hampton, VA (United States)] [and others

1995-07-15

254

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)

1995-04-01

255

A height resolved global view of dust aerosols from the first year CALIPSO lidar measurements  

NASA Astrophysics Data System (ADS)

Based on the first year of CALIPSO lidar measurements under cloud-free conditions, a height-resolved global distribution of dust aerosols is presented for the first time. Results indicate that spring is the most active dust season, during which ˜20% and ˜12% of areas between 0 and 60°N are influenced by dust at least 10% and 50% of the time, respectively. In summer within 3-6 km, ˜8.3% of area between 0 and 60°N is impacted by dust at least 50% of the time. Strong seasonal cycles of dust layer vertical extent are observed in major source regions, which are similar to the seasonal variation of the thermally driven boundary layer depth. The arid and semiarid areas in North Africa and the Arabian Peninsula are the most persistent and prolific dust sources. African dust is transported across the Atlantic all yearlong with strong seasonal variation in the transport pathways mainly in the free troposphere in summer and at the low altitudes in winter. However, the trans-Atlantic dust is transported at the low altitudes is important for all seasons, especially transported further cross the ocean. The crossing Atlantic dusty zones are shifted southward from summer to winter, which is accompanied by a similar southward shift of dust-generating areas over North Africa. The Taklimakan and Gobi deserts are two major dust sources in East Asia with long-range transport mainly occurring in spring. The large horizontal and vertical coverage of dust aerosols indicate their importance in the climate system through both direct and indirect aerosol effects.

Liu, Dong; Wang, Zhien; Liu, Zhaoyan; Winker, Dave; Trepte, Charles

2008-08-01

256

Development of radar and lidar simulator and its application to the evaluation of the cloud and aerosol microphysics in the AGCM  

NASA Astrophysics Data System (ADS)

The radar and lidar simulator is presented for the evaluation of the cloud and aerosol microphysical properties reproduced in the models such as the AGCM and the NHM. There are two possible ways to evaluate the macro-scale and microphysical properties of clouds and aerosols simulated in the models; one is the comparison of the simulated microphysics with the retrieved ones by the algorithms. The other is the direct comparisons of the observed and simulated radar and lidar signals. The simulator is designed to use the outputs about the cloud and aerosol microphysical properties from the models to simulate the observables obtained by the radar and the lidar. It can treat ice and water clouds as well as aerosols. Particle shapes and orientations of ice particles are also taken into account in the estimation of the backscattering and extinction properties of ice clouds in the radar and lidar wavelengths. Four aerosol types are also considered; sulfate, carbonaceous, sea-salt and dust particles, in the lidar simulations. The simulator has a function to generate both of the ground-based and space-borne radar and lidar signals from the output parameters. It is worth to note that the same cloud and aerosol particle models and their scattering properties are also used in the retrieval algorithms for cloud and aerosol microphysics from the space-borne or ground-based radar and lidar observations. This consistency assures the further investigation of the information content obtained in the comparisons of observed and simulated signals. Some application of the radar and lidar simulator is demonstrated for the comparison of the shipborne measurements and the AGCM. We also present the comparisons of the radar reflectivity observed in CloudSat and the lidar backscattering coefficients at 532nm and 1064nm and depolarization ratio in CALIPSO with the simulated signals in the GCM. Extension of the simulator for the EarthCARE CPR and ATLID lidar is also introduced. Information content in the comparisons of the observed and simulated signals is discussed together with the analysis of the comparisons of retrieved and simulated microphysics of clouds and aerosols. The essential parts of the radar and lidar simulator have been incorporated into the Joint Simulator for Satellite Sensors(J-simulator).

Okamoto, H.; Sato, K.; Takemura, T.; Hagihara, Y.; Nishizawa, T.

2011-12-01

257

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

258

Characterization of convection-related parameters by Raman lidar: Analysis of selected case studies from the Convective and Orographically-induced Precipitation Study  

NASA Astrophysics Data System (ADS)

This paper illustrates an approach to determine the convective available potential energy (CAPE) and the convective inhibition (CIN) based on the use of data from a Raman lidar system. The use of Raman lidar data allows to provide high temporal resolution (5 min) measurements of CAPE and CIN and follow their evolution over extended time period covering the full cycle of convective activity. Lidar-based measurements of CAPE and CIN are obtained from Raman lidar measurements of the temperature profile and the surface measurements of temperature, pressure and dew point temperature provided from a surface weather station. The approach is tested and applied to the data collected by the Raman lidar system BASIL, which was operational in Achern (Black Forest, Lat: 48.64 ° N, Long: 8.06 ° E, Elev.: 140 m) in the period 01 June - 31 August 2007 in the frame of the Convective and Orographically-induced Precipitation Study (COPS), held in Southern Germany and Eastern France. Reported measurements are found to be in good agreement with simultaneous measurements obtained from the radiosondes launched in Achern and with estimates from different mesoscale models. An estimate of the different random error sources affecting the measurements of CAPE and CIN has also been performed, together with a detail sensitivity study to quantify the different systematic error sources. Preliminary results from this study will be illustrated and discussed at the Conference.

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

2012-04-01

259

Boundary layer heights from Doppler lidar using aerosol backscatter and wind data  

NASA Astrophysics Data System (ADS)

The height of the convective boundary layer (CBL) is estimated using the 2 micron Doppler lidar ‘WindTracer '. The instrument provides an along-beam-resolution with independent range gates of 72 m length, and a temporal resolution of 1 Hz (accumulating 500 pulses). Two sets of automatically working algorithms were implemented, one based on aerosol backscatter, the second on vertical wind velocity variance. An overview about the different Doppler lidar based techniques for CBL determination and an intercomparison of the respective results based on measurements over coastal gently rolling terrain (Convective Storm Initiation Project, CSIP, 2005), over continental gently rolling terrain, as well as over complex terrain (Convective and Orographically-induced Precipitation Study, COPS, 2007) are presented. Additionally the influence of the local vertical wind field on small-scale boundary layer height fluctuations, which are known to be important for entrainment processes, is investigated. Using the signal-to-noise-ratio of the Doppler spectra, a non-calibrated aerosol backscatter profile can be determined. Aerosol backscatter shows typically a large negative gradient at the interface between the mixed layer and the free atmosphere. Four well established algorithms to detect automatically the boundary layer height were used: (i) a threshold method, (ii) the detection of the minimum derivative, (iii) a fit to an idealized profile, described by an error function and (iv) a simple wavelet method. A comparison between the different techniques and the corresponding CBL-heights will be given in the presentation. The advantage of using aerosol backscatter data is the extremely high temporal resolution of 0.1 Hz. This provides the possibility to analyse the influence of local vertical wind fluctuations on the small-scale variability of the boundary layer height. The simple approach of a direct correlation between an updraft and a corresponding CBL increase and vice versa seems to be invalid. Rather the small-scale CBL height fluctuations are determined by processes, the interface between CBL and the free atmosphere experienced upstream. The second set of methods to determine CBL heights uses the wind velocity information. The vertical wind velocity variance is a direct measure for turbulence. Therefore this method determines a boundary layer height in the sense of the original mixed layer definition. Three different techniques are used: (i) a threshold technique, (ii) the maximum vertical velocity variance approach and (iii) a fit to an idealized profile described by an empirical profile from previous studies. A comparison between the different techniques will be given in the presentation. Comparing the results from the two sets of boundary layer height estimations, differences between the aerosol-based height and the turbulence height, especially during periods of CBL growth in the morning and during the afternoon transition time, were obvious. The daily evolutions based on the two sets, were compared with each other and to boundary layer heights determined from potential temperature profiles measured by radiosondes.

Träumner, K.; Wieser, A.; Corsmeier, U.; Kottmeier, Ch.

2009-09-01

260

Active Raman sounding of the earth's water vapor field.  

PubMed

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. PMID:16029854

Tratt, David M; Whiteman, David N; Demoz, Belay B; Farley, Robert W; Wessel, John E

2005-08-01

261

Lidar measurements of sub-visible aerosol layers in the free troposphere at a tropical coastal station in Trivandrum, India  

NASA Astrophysics Data System (ADS)

Lidar observations had been conducted to study the long-range transport of aerosol and their effect at tropical station, Trivandrum during the period of 2001-2003. The presence of aerosol layers was observed on many days below about 5 km during the above period. The monthly values of aerosol extinction coefficient profile showed the presence of aerosol layer in the height region up to about 5 km during the summer monsoon periods. However, during the Asian winter monsoon period the aerosol layers were observed in the altitude region between 0.6 and 3 km. The extinction values were high in the winter season and were typically found to be 3.4×10-4 m-1. The aerosol optical depth was calculated by integrating the extinction values in the aerosol layer region and it was found to be between 0.2 and 0.35. The plausible reasons for the formation of these layers were explained using the wind circulation pattern and air back trajectories.

Veerabuthiran, Sangaipillai; Satyanarayana, Malladi; Sreeja, Rajappan; Presennakumar, Bhargavan; Muraleedharen Nair, Sivarama Pillai; Ramakrishna Rao, Duggirala; Pillai Mohankumar, Santhibhavan Vasudevan

2006-12-01

262

Micro pulse lidar observation of high altitude aerosol layers at Visakhapatnam located on the east coast of India  

NASA Astrophysics Data System (ADS)

Aerosol back scatter profiles obtained using a micro pulse lidar at Visakhapatnam, a station located on the east coast of peninsular India show certain high altitude aerosol layers during the months of March/April 2005, 2006. Co-located aerosol optical depth measurements show an increase in AOD by 0.05 to 0.25 during the event when the layers were observed. The prevailing meteorology does not indicate any possible local entrainment of aerosol leading to the formation of elevated layers due to boundary layer dynamics. The 7 day back trajectory analysis shows that the possible origin of the layers could be from Arabia in 60% of the cases while it is from Indian sub-continent during the rest of the events. When the air mass flow is from the Indian sub-continent, there is a proportional increase in MODIS derived aerosol column fine mode fraction though it is not observed at the surface level. During the events when air mass flow is from Arabia, such an increase in column fine mode fraction was not observed but the angstrom size index which is a measure of the aerosol size distribution was low indicating that the elevated layers of Arabian origin could contain significant fraction of dust aerosol.

Niranjan, K.; Madhavan, B. L.; Sreekanth, V.

2007-02-01

263

Aerosol properties computed from aircraft-based observations during the ACE-Asia campaign: 2. A case study of lidar ratio closure  

SciTech Connect

For a vertical profile with three distinct layers (marine boundary, pollution and dust layers), observed during the ACE-Asia campaign, we carried out a comparison between the modeled lidar ratio vertical profile and that obtained from co-located airborne NASA AATS-14 sunphotometer and shipborne Micro-Pulse Lidar (MPL) measurements. The vertically resolved lidar ratio was calculated from two size distribution vertical profiles – one obtained by inversion of sunphotometer-derived extinction spectra, and one measured in-situ – combined with the same refractive index model based on aerosol chemical composition. The aerosol model implies single scattering albedos of 0.78 – 0.81 and 0.93 – 0.96 at 0.523 ?m (the wavelength of the lidar measurements), in the pollution and dust layers, respectively. The lidar ratios calculated from the two size distribution profiles agree closely in the dust layer; they are however, significantly lower than the lidar ratios derived from combined lidar and sunphotometer measurements. Uncertainties in aerosol size distributions and refractive index only partly explain these differences, suggesting that particle nonsphericity in this layer is an additional explanation. In the pollution layer, the two size distribution profiles yield lidar ratios that agree within the estimated uncertainties. The retrieved size distributions result in a lidar ratio which is in closer agreement with that derived from lidar/sunphotometer measurements in this layer, with still large differences at certain altitudes (the largest relative difference was 46%). We explain these differences by non-uniqueness of the result of the size distribution retrieval, by a lack of information on the mixing state of particles, and the vertical variability of the particle refractive index.

Kuzmanoski, Maja; Box, M. A.; Schmid, Beat; Box, G. P.; Wang, Jian; Russel, P. R.; Bates, D.; Jonsson, Haf; Welton, E. J.; Seinfeld, J. H.

2007-04-03

264

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

265

Characterization of Iceland volcanic aerosols by UV-polarization lidar at Lyon, SW Europe  

NASA Astrophysics Data System (ADS)

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

Miffre, Alain; David, Grégory; Thomas, Benjamin; Rairoux, Patrick

2010-10-01

266

An automatic planetary boundary layer height detection with a compact aerosol UV lidar  

NASA Astrophysics Data System (ADS)

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

Sauvage, L.; Loaëc, S.; Lolli, S.; Boquet, M.; El Filali, A.

2010-10-01

267

The Vertical Distribution of Aerosols Over the Atmospheric Radiation Measurement Southern Great Plains Site Measured versus Modeled  

SciTech Connect

Aerosol extinction profiles measured by the Department of Energy Atmospheric Radiation Measurement (ARM) Climate Research Facility Raman lidar are 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) project. This project seeks to diagnose aerosol modules of global models and subsequently identify and eliminate weak components in aerosol modules used for global modeling; AEROCOM activities also include assembling data sets to be used in the evaluations. The AEROCOM average aerosol extinction profiles typically show good agreement with the Raman lidar profiles for altitudes above about 2 km; below 2 km the average model profiles are significantly (30-50%) lower than the Raman lidar profiles. The vertical variability in the average aerosol extinction profiles simulated by these models is less than the variability in the corresponding Raman lidar pro files. The measurements also show a much larger diurnal variability than the Interaction with Chemistry and Aerosols (INCA) model, particularly near the surface where there is a high correlation between aerosol extinction and relative humidity.

Ferrare, R.; Turner, D.D.; Clayton, M.; Guibert, S.; Schulz, M.; Chin, M.

2005-03-18

268

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

269

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

270

On retrieval of lidar extinction profiles using Two-Stream and Raman techniques  

Microsoft Academic Search

The Two-Stream technique employs simultaneous measurements performed by two elastic backscatter lidars pointing at each other to sample into the same atmosphere. It allows for a direct retrieval of the extinction coefficient profile from the ratio of the two involved lidar signals. During a number of Alfred-Wegener-Institute (AWI) campaigns dedicated to Arctic research, the AWI's Polar 2 aircraft with the

I. S. Stachlewska; C. Ritter

2010-01-01

271

On retrieval of lidar extinction profiles using Two-Stream and Raman techniques  

Microsoft Academic Search

The Two-Stream technique employes simultaneous measurements performed by two elastic backscatter lidars aiming at each other to sample into the same atmosphere. It allows for a direct retrieval of the extinction coefficient profile from the ratio of the two involved lidar signals. During a few Alfred-Wegener-Institute's (AWI) campaigns dedicated to the Arctic research, the AWI's Polar 2 aircraft with the

I. S. Stachlewska; C. Ritter

2009-01-01

272

Dust, biomass burning smoke, and anthropogenic aerosol detected by polarization-sensitive Mie lidar measurements in Mongolia  

NASA Astrophysics Data System (ADS)

Polarization-sensitive Mie-scattering lidars were installed for dust storm monitoring at Sainshand and Zamyn-Uud in the Gobi Desert and at the Mongolian capital city of Ulaanbaatar in 2007. We studied the temporal and spatial distributions and transportation of dust, elevated dust, biomass burning smoke, and anthropogenic aerosol by using lidar measurements from the end of 2007 to the first half of 2010. The study results show that the maximum height of dust layers over the Gobi Desert of Mongolia during dust event periods varied from 0.5 to 5.5 km above the ground level (AGL). The 95th percentile level of dust vertical distribution was found at 4 and 4.5 km for Zamyn-Uud and Sainshand, respectively. The averaged maximum height of dust layers during dust events was 2.0-2.2 km AGL at those Gobi sites. The lidar measurements also revealed transport of dust layers elevated in the atmosphere. Base heights of elevated dust layers varied from 0.5 to 2.5 km AGL, while maximum heights from 2.5 to 4.5 km AGL. Backward air trajectory analyses suggested source areas of the elevated dust that transported from other source regions to southeastern Mongolia. A detail study was conducted of the dust event in 19-20 May 2008. Hourly maximum dust concentrations of PM10 (PM2.5) reached 1139-1409 (384-404) ?g m-3 during the dust event episode. Dust concentration of PM10 had high correlations with visibilities. Threshold winds for dust emission were determined at Sainshand and Zamyn-Uud. The lidar measurements at the three sites detected vertical profiles of biomass burning smoke and anthropogenic aerosol with top heights of 3-4 km AGL.

Jugder, Dulam; Sugimoto, Nobuo; Shinoda, Masato; Kimura, Reiji; Matsui, Ichiro; Nishikawa, Masataka

2012-07-01

273

LIDAR technique: a central puzzle piece to build an integrated observation - modeling approach for air mass aerosols concentration evaluation  

NASA Astrophysics Data System (ADS)

This paper presents a study of the temporal and vertical variation of mixed aerosol mass concentration near Bucharest during a dedicated observation campaign performed in summer 2012. To obtain the vertical mass concentrations profiles a combination of measured (mainly based on LIDAR technique) and modeled data was used. This method is based on the hypothesis that any mixture in the atmosphere can be described as a combination of low-depolarizing and high-depolarizing particles of a particular type. It uses the method proposed by Tesche et al. (2009), combined with forward simulations (i.e. OPAC). Based on supplementary information (e.g. preliminary assessment of aerosol source from forecast models and back trajectories) and several optical indicators (Angstrom exponent, LIDAR ratio, particle depolarization, AOD we built an approach to 2 cases of aerosol mixture, and validate the results using other information sources: sun photometry, forecasts, back trajectories. The first case was proved to be a smoke predominant layer, the second a Saharan dust predominant layer. Information from various data sources (DREAM, HYSPLIT, AERONET, MODIS) was consistent with our retrievals.

Tudose, Ovidiu-Gelu

2013-04-01

274

Comparison of CALIPSO aerosol optical depth retrievals to AERONET measurements, and a climatology for the lidar ratio of dust  

NASA Astrophysics Data System (ADS)

We compared CALIPSO column aerosol optical depths at 0.532 ?m to measurements at 147 AERONET sites, synchronized to within 30 min of satellite overpass times during a 3-yr period. We found 677 suitable overpasses, and a CALIPSO bias of -13% relative to AERONET for the entire data set; the corresponding absolute bias is -0.029, and the standard deviation of the mean (SDOM) is 0.014. Consequently, the null hypothesis is rejected at the 97% confidence level, indicating a statistically significant difference between the datasets. However, if we omit CALIPSO columns that contain dust from our analysis, the relative and absolute biases are reduced to -3% and -0.005 with a standard error of 0.016 for 449 overpasses, and the statistical confidence level for the null hypothesis rejection is reduced to 27%. We also analyzed the results according to the six CALIPSO aerosol subtypes and found relative and absolute biases of -29% and -0.1 for atmospheric columns that contain the dust subtype exclusively, but with a relatively high correlation coefficient of R = 0.58; this indicates the possibility that the assumed lidar ratio (40 sr) for the CALIPSO dust retrievals is too low. Hence, we used the AERONET size distributions, refractive indices, percent spheres, and forward optics code for spheres and spheroids to compute a lidar ratio climatology for AERONET sites located in the dust belt. The highest lidar ratios of our analysis occur in the non-Sahel regions of Northern Africa, where the median lidar ratio at 0.532 ?m is 55.4 sr for 229 retrievals. Lidar ratios are somewhat lower in the African Sahel (49.7 sr for 929 retrievals), the Middle East (42.6 sr for 489 retrievals), and Kanpur, India (43.8 sr for 67 retrievals). We attribute this regional variability in the lidar ratio to the regional variability of the real refractive index of dust, as these two parameters are highly anti-correlated (correlation coefficients range from -0.51 to -0.85 for the various regions). The AERONET refractive index variability is consistent with the variability of illite concentration in dust across the dust belt.

Schuster, G. L.; Vaughan, M.; MacDonnell, D.; Su, W.; Winker, D.; Dubovik, O.; Lapyonok, T.; Trepte, C.

2012-08-01

275

Vertical distribution of atmospheric particles and water vapor densities in the free troposphere: Lidar measurement in spring and summer in Nagoya, Japan  

Microsoft Academic Search

Density distributions of atmospheric water vapor and aerosol particles in the troposphere were observed from April to August 1994 in Nagoya, Japan, with a Raman-scattering lidar. In spring, highly concentrated particle layers were frequently observed in the free troposphere, and in summer air mass with high relative humidity was detected. These suggest the possibility that density distributions of aerosol particles

S. A. Kwon; Y. Iwasaka; T. Shibata; T. Sakai

1997-01-01

276

LIDAR observations of lower stratospheric aerosols over South Africa linked to large scale transport across the southern subtropical barrier  

NASA Astrophysics Data System (ADS)

The study of the variability of stratospheric aerosols and the transfer between the different atmospheric regions improves our understanding of dynamical processes involved in isentropic exchanges that take place episodically in the lower stratosphere through the subtropical barrier. One useful approach consists in combining in situ ground-based and global measurements with numerical analyses. The present paper reports on a case study of a horizontal transfer evidenced first by Rayleigh-Mie LIDAR observations over Durban (/29.9°S, /31.0°E, South Africa). Additional data from MeteoSat and SAGE-2 experiments, and from ECMWF meteorological analysis have been used in this study. Contour advection maps of potential vorticity from the MIMOSA model derived from ECMWF fields, were also used. By the end of April, 1999, LIDAR observations showed that aerosol extinction, in the lower stratosphere, has increased significantly and abnormally in comparison with other LIDAR and SAGE-2 observations recorded for the period from April 20 to June 14, 1999. The dynamical context of this case study seems to exclude the possibility of a local influence of the subtropical jet stream or tropical convection, which could inject air masses enriched with tropospheric aerosols into the stratosphere. On the contrary, a high-resolution model based on PV advection calculations and ECMWF meteorological analyses shows that air masses are isentropically advected from the equatorial zone close to Brazil. They cross the southern barrier of the tropical reservoir due to laminae stretching and reach the southern subcontinent of Africa 5-6 days later.

Bencherif, H.; Portafaix, T.; Baray, J. L.; Morel, B.; Baldy, S.; Leveau, J.; Hauchecorne, A.; Keckhut, P.; Moorgawa, A.; Michaelis, M. M.; Diab, R.

2003-04-01

277

Vertical structure and microphysical properties of Saharan dust retrieved from shipborne lidar measurements  

Microsoft Academic Search

A unique data set of ship borne lidar measurements of Saharan dust layers above the Atlantic ocean obtained aboard the research vessel Polarstern with a mobile Aerosol Raman Lidar (MARL) during the LIMPIDO campaign in 2000 will be presented. Between 10^oN and 30^oN extended Saharan dust layers were observed in an altitude range between 2 and 6~km. The continental, North

F. Immler; O. Schrems

2003-01-01

278

Characterization of gas-aerosol interaction kinetics using morphology dependent stimulated Raman scattering. 1992 Annual summary  

SciTech Connect

This study is aimed at characterizing the influence of aerosol surface structure on the kinetics of gas-aerosol interactions. Changes in gas phase chemical reaction rates as a function of exposure to a specific aerosol are measured with aerosols having different surface properties due to the composition and/or temperature of the material making up the aerosol. The kinetic data generated can be used directly in atmospheric modeling calculations. The surface structure of the aerosol is using morphology-dependent enhancement of simulated Raman scattering (MDSRS). Detailed dynamics of gas-aerosol interactions can be obtained by correlating the change in the reaction rate with change in surface structure and by monitoring the change in aerosol surface structure during, the course of the reaction. This dynamics information can be used to generate kinetic data for systems which are similar in nature to those studied, but are not amenable to laboratory investigation. We show here that increased MDSRS sensitivity is achieved by using an excitation laser source that has a narrow linewidth and we have been able to detect sulfate anion concentrations much lower than previously reported. We have shown that the linewidth of the MDSRS mode excited in a droplet is limited by the laser linewidth. This is a positive result for it eases our ability to quantify the MDSRS gain equation. This result also suggests that MDSRS signal size should be independent of droplet size, and preliminary experiments confirm this hypothesis.

Aker, P.M.

1993-01-30

279

Characterization of gas-aerosol interaction kinetics using morphology dependent stimulated Raman scattering  

SciTech Connect

This study is aimed at characterizing the influence of aerosol surface structure on the kinetics of gas-aerosol interactions. Changes in gas phase chemical reaction rates as a function of exposure to a specific aerosol are measured with aerosols having different surface properties due to the composition and/or temperature of the material making up the aerosol. The kinetic data generated can be used directly in atmospheric modeling calculations. The surface structure of the aerosol is using morphology-dependent enhancement of simulated Raman scattering (MDSRS). Detailed dynamics of gas-aerosol interactions can be obtained by correlating the change in the reaction rate with change in surface structure and by monitoring the change in aerosol surface structure during, the course of the reaction. This dynamics information can be used to generate kinetic data for systems which are similar in nature to those studied, but are not amenable to laboratory investigation. We show here that increased MDSRS sensitivity is achieved by using an excitation laser source that has a narrow linewidth and we have been able to detect sulfate anion concentrations much lower than previously reported. We have shown that the linewidth of the MDSRS mode excited in a droplet is limited by the laser linewidth. This is a positive result for it eases our ability to quantify the MDSRS gain equation. This result also suggests that MDSRS signal size should be independent of droplet size, and preliminary experiments confirm this hypothesis.

Aker, P.M.

1993-01-30

280

Four-wavelength lidar evaluation of particle characteristics and aerosol densities  

NASA Astrophysics Data System (ADS)

The SRI International four-wavelength (0.53, 1.06, 3.8, 10.6 micron) lidar systems was used during the SNOW-ONE-B and Smoke Week XI/SNOW-TWO field experiments to validate its capabilities in assessing obscurant optical and physical properties. The lidar viewed along a horizontal path terminated by a passive reflector. Data examples were analyzed in terms of time-dependent transmission, wavelength dependence of optical depth, and range-resolved extinction coefficients. Three methods were used to derive extinction data from the lidar signatures. These were target method, Klett method and experimental data method. The results of the field and analysis programs are reported in the journal and conference papers that are appended to this report, and include: comparison study of lidar extinction methods, submitted to applied optics, error analysis of lidar solution techniques for range-resolved extinction coefficients based on observational data, smoke/obscurants symposium 9, Four--Wavelength Lidar Measurements from smoke week 6/SNOW-TWO, smoke/obscurants symposium 8, SNOW-ONE-B multiple-wavelength lidar measurements. Snow symposium 3, and lidar applications for obscurant evaluations, smoke/obscurants Symposium 7. The report also provides a summary of background work leading to this project, and of project results.

Uthe, E. E.; Livingston, J. M.; Delateur, S. A.; Nielsen, N. B.

1985-06-01

281

Aerosol stratification characterization of an astronomical site by means of a backscatter lidar at the Roque de los Muchachos Observatory  

NASA Astrophysics Data System (ADS)

The Roque de los Muchachos Observatory, located on the island of La Palma in the Canary Islands, is home of many astronomical facilities. In the context of the Extremely Large Telescope Design Study, an intensive lidar campaign was performed in the ORM near the Jacobus Kapteyn Telescope (17°52'41.2" W, 28°45'40.1" N, 2395 m asl) between 26th May and 14th June 2008. The goal of the campaign was to characterize the atmosphere in terms of planetary boundary layer height and aerosol stratification vs. synoptic conditions. As a by-product an estimate of the aerosol optical thickness was also obtained and compared to the total atmospheric extinction coefficient measured by the Carlsberg Meridian Telescope.

Sicard, M.; Tomás, S.; Md Reba, M. N.; Comerón, A.; Batet, O.; Muñoz-Porcar, C.; Rodriguez, A.; Rocadenbosch, F.; Muñoz-Tunon, C.; Fuensalida, J. J.

2009-09-01

282

Correlative ground-based lidar measurements for LITE  

NASA Astrophysics Data System (ADS)

The lidar in-space technology experiment (LITE) has been developed at the NASA Langley Research Center to fly on the Space Shuttle and demonstrate the utility of lidar systems in space. An extensive correlative measurements campaign to validate LITE measurements with coincident measurements made with reliable ground-based and balloon-borne sensors was carried out both in Napoli and Potenza in the period September 10-19, 1994. The lidar in Napoli is based on a Xe:F excimer laser (351 nm), while the lidar in Potenza is based on a Nd:YAG laser operating both on the 2nd (532 nm) and 3rd (355 nm) harmonic. During this intense campaign we performed both elastic and Raman measurements for molecular nitrogen. Solar irradiance spectra at ground level were measured by an Optical Spectra Analyzer in the spectral region 0.4-1.1 micrometers , obtaining both columnar water vapor and aerosol load. Aerosol backscattering data will be presented. Elastic and nitrogen Raman signals are used for measuring atmospheric transmissivity. Finally the density and temperature profiles obtained from the simultaneous measurement of the elastic and the N2 Raman signal will be presented. Simultaneous radiosonde measurements of temperature, pressure, and relative humidity will be used to compare lidar data.

Cuomo, Vincenzo; Di Girolamo, P.; Esposito, F.; Pappalardo, Gelsomina; Romano, F.; Serio, Carmine; Spinelli, N.; Armenante, M.; Bartoli, B.; Berardi, V.; Bruzzese, Riccardo; Bellecci, C.; Caputi, G. E.; De Donato, F.; Gaudio, P.; Valentini, Mario

1995-09-01

283

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

284

Raman Lidar Observations of a MCS in the frame of the Convective and Orographically-induced Precipitation Study  

NASA Astrophysics Data System (ADS)

The Raman lidar system BASIL was deployed in Achern (Supersite R, Lat: 48.64° N, Long: 8.06° E, Elev.: 140 m) in the frame of the Convective and Orographically-induced Precipitation Study. On 20 July 2007 a frontal zone passed over the COPS region, with a Mesoscale Convective System (MCS) imbedded in it. BASIL was operated continuously during this day, providing measurements of temperature, water vapour, particle backscattering coefficient at 355, 532 and 1064 nm, particle extinction coefficient at 355 and 532 nm and particle depolarization at 355 and 532 nm. The thunderstorm approaching determined the lowering of the anvil clouds, which is clearly visible in the lidar data. A cloud deck is present at 2 km, which represents a mid-level outflow from the thunderstorm/MCS. The mid-level outflow spits out hydrometeor-debris (mostly virga) and it is recycled back into it. The MCS modified the environment at 1.6-2.5 km levels directly (outflow) and the lower levels through the virga/precipitation. Wave structures were observed in the particle backscatter data. The wave activity seems to be a reflection of the shear that is produced by the MCS and the inflow environmental wind. Measurements in terms of particle backscatter and water vapour mixing ratio are discussed to illustrate the above phenomena.

di Girolamo, Paolo; Bhawar, Rohini; Summa, Donato; di Iorio, Tatiana; Demoz, Belay B.

2009-03-01

285

Comparison of upper tropospheric water vapor from GOES, Raman lidar, and Cross-chain Loran Atmospheric Sounding System measurements  

SciTech Connect

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. [Princeton Univ., Princeton, NJ (United States)]|[Univ. of Wisconsin, Madison, WI (United States)]|[NASA, Goddard Space Flight Center, Greenbelt, MD (United States)]|[Hughes STX Corp., Lanham, MD (United States)

1994-10-01

286

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

287

Aerosol measurements at L'Aquila EARLINET station in central Italy: Impact of local sources and large scale transport resolved by LIDAR  

NASA Astrophysics Data System (ADS)

Surface measurements of multi-channel aerosol mass concentration are analyzed together with LIDAR observations at L'Aquila, a central Italy site part of the EARLINET network (http://www.earlinet.org/), with the main purpose of discriminating aerosol particles originated from in-situ sources and those transported from remote sites, and their effects on local aerosol load and on the aerosol optical depth. Four major episodes of both Saharan desert and forest fire aerosol transport were observed during spring–summer months of 2007. The analysis of these events shows that at the ground surface the aerosol mass concentration increase due to desert dust particles is about 160% of the PMcoarse, whereas forest fires increase the PM1 by about 150%, with respect to typical reference unperturbed conditions during the same time period. Calculation of the aerosol optical depth (AOD) from the LIDAR retrieved aerosol extinction at 351 nm shows that the corresponding increases in AOD are 95% for Saharan dust and 220% in case of forest fires. These results show that in a site impacted by aerosol transport from the desert and frequent forest fires, the first has the bigger effect in terms of local aerosol load in the coarse mode, whereas the latter impacts more the PM1 and the UV aerosol extinction and optical depth. A well tested radiative transfer model (TUV, Madronich and Floke, 1998), extended to the solar near infrared spectrum, has been used to calculate the top-of-atmosphere radiative change due to these transported aerosols: the calculated change is of the order of 0.5–1 W/m2 for forest fire events end 1–2 W/m2 for Saharan dust. The larger impact of desert aerosols is due to their much larger effective radius with respect to forest fire aerosols, whose scattering efficiency rapidly declines for solar wavelengths in the visible and near infrared range.

Pitari, Giovanni; Di Carlo, Piero; Coppari, Eleonora; De Luca, Natalia; Di Genova, Glauco; Iarlori, Marco; Pietropaolo, Ermanno; Rizi, Vincenzo; Tuccella, Paolo

2013-01-01

288

Evaluating CALIOP Nighttime Level 2 Aerosol Profile Retrievals Using a Global Transport Model Equipped with Two-Dimensional Variational Data Assimilation and Ground-Based Lidar Measurements  

NASA Astrophysics Data System (ADS)

Launched in 2006, the Cloud Aerosol Lidar with Orthogonal Polarization instrument (CALIOP) flown aboard the NASA/CNES Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite has collected the first high-resolution global, inter-seasonal and multi-year measurements of aerosol structure. Profiles for aerosol particle extinction coefficient and column-integrated optical depth (AOD) are unique and highly synergistic satellite measurements, given the limitations of passive aerosol remote sensors from resolving information vertically. However, accurate value-added (Level 2.0) CALIOP aerosol products require comprehensive validation of retrieval techniques and calibration stability. Daytime Level 2.0 CALIOP AOD retrievals have been evaluated versus co-located NASA Moderate Resolution Imaging Spectroradiometer (MODIS-AQUA) data. To date, no corresponding investigation of nighttime retrieval performance has been conducted from a lack of requisite global nighttime validation datasets. In this paper, Version 3.01 CALIOP 5-km retrievals of nighttime 0.532 ?m AOD from 2007 are evaluated versus corresponding 0.550 ?m AOD analyses derived with the global 1° x 1° U. S. Navy Aerosol Analysis and Prediction System (NAAPS). Mean regional profiles of CALIOP nighttime 0.532 ?m extinction coefficient are assessed versus NASA Micropulse Lidar Network and NIES Skynet Lidar Network measurements. NAAPS features a two-dimensional variational assimilation procedure for quality-assured MODIS and NASA Multi-angle Imaging Spectroradiometer (MISR) AOD products. Whereas NAAPS nighttime AOD datasets represent a nominal 12-hr forecast field, from lack of MODIS/MISR retrievals for assimilation in the dark sector of the model, evaluation of NAAPS 00-hr analysis and 24-hr forecast skill versus MODIS and NASA Aerosol Robotic Network (AERONET) indicates adequate stability for conducting this study. Corresponding daytime comparisons of CALIOP retrievals with NAAPS, MPLNET and Skynet are described as context.

Campbell, J. R.; Tackett, J. L.; Reid, J. S.; Zhang, J.; Westphal, D. L.; Vaughan, M.; Winker, D. M.; Welton, E. J.; Prospero, J. M.; Shimizu, A.; Sugimoto, N.

2011-12-01

289

Hybrid regularization method for the ill-posed inversion of multiwavelength lidar data in the retrieval of aerosol size distributions.  

PubMed

A specially developed method is proposed to retrieve the particle volume distribution, the mean refractive index, and other important physical parameters, e.g., the effective radius, volume, surface area, and number concentrations of tropospheric and stratospheric aerosols, from optical data by use of multiple wavelengths. This algorithm requires neither a priori knowledge of the analytical shape of the distribution nor an initial guess of the distribution. As a result, even bimodal and multimodal distributions can be retrieved without any advance knowledge of the number of modes. The nonlinear ill-posed inversion is achieved by means of a hybrid method combining regularization by discretization, variable higher-order B-spline functions and a truncated singular-value decomposition. The method can be used to handle different lidar devices that work with various values and numbers of wavelengths. It is shown, to my knowledge for the first time, that only one extinction and three backscatter coefficients are sufficient for the solution. Moreover, measurement errors up to 20% are allowed. This result could be achieved by a judicious fusion of different properties of three suitable regularization parameters. Finally, numerical results with an additional unknown refractive index show the possibility of successfully recovering both unknowns simultaneously from the lidar data: the aerosol volume distribution and the refractive index. PMID:18357119

Böckmann, C

2001-03-20

290

Raman lidar observations of a Saharan dust outbreak event: Characterization of the dust optical properties and determination of particle size and microphysical parameters  

NASA Astrophysics Data System (ADS)

The Raman lidar system BASIL was operational in Achern (Black Forest) between 25 May and 30 August 2007 in the framework of the Convective and Orographically-induced Precipitation Study (COPS). The system performed continuous measurements over a period of approx. 36 h from 06:22 UTC on 1 August to 18:28 UTC on 2 August 2007, capturing the signature of a severe Saharan dust outbreak episode. The data clearly reveal the presence of two almost separate aerosol layers: a lower layer located between 1.5 and 3.5 km above ground level (a.g.l.) and an upper layer extending between 3.0 and 6.0 km a.g.l. The time evolution of the dust cloud is illustrated and discussed in the paper in terms of several optical parameters (particle backscatter ratio at 532 and 1064 nm, the colour ratio and the backscatter Angström parameter).An inversion algorithm was used to retrieve particle size and microphysical parameters, i.e., mean and effective radius, number, surface area, volume concentration, and complex refractive index, as well as the parameters of a bimodal particle size distribution (PSD), from the multi-wavelength lidar data of particle backscattering, extinction and depolarization. The retrieval scheme employs Tikhonov's inversion with regularization and makes use of kernel functions for randomly oriented spheroids. Size and microphysical parameters of dust particles are estimated as a function of altitude at different times during the dust outbreak event. Retrieval results reveal the presence of a fine mode with radii of 0.1-0.2 ?m and a coarse mode with radii of 3-5 ?m both in the lower and upper dust layers, and the dominance in the upper dust layer of a coarse mode with radii of 4-5 ?m. Effective radius varies with altitude in the range 0.1-1.5 ?m, while volume concentration is found to not exceed 92 ?m3 cm-3. The real and imaginary part of the complex refractive index vary in the range 1.4-1.6 and 0.004-0.008, respectively.

di Girolamo, Paolo; Summa, Donato; Bhawar, Rohini; di Iorio, Tatiana; Cacciani, Marco; Veselovskii, Igor; Dubovik, Oleg; Kolgotin, Alexey

2012-04-01

291

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

292

Chemical characterization of aerosol particles by laser Raman spectroscopy. Revision  

SciTech Connect

The importance of aerosol particles in many branches of science, such as atmospheric chemistry, combustion, interfacial science, and material processing, has been steadily growing during the past decades. One of the unique properties of these particles is the very high surface-to-volume ratios, thus making them readily serve as centers for gas-phase condensation and heterogeneous reactions. These particles must be characterized by size, shape, physical state, and chemical composition. Traditionally, optical elastic scattering has been applied to obtain the physical properties of these particle (e.g., particle size, size distribution, and particle density). These physical properties are particularly important in atmospheric science as they govern the distribution and transport of atmospheric aerosols.

Fung, K.H.

1999-12-01

293

Raman scattering in the Jupiter's atmosphere and optical properties of atmospheric aerosol  

NASA Astrophysics Data System (ADS)

The basis of nonlinear atmospheric optic is considered here. When Sun radiation cross the Jupiter's atmosphere, such nonlinear optical effect as Raman scattering will be appear. For our investigations, we used the spectral observations received by E.Karkoshka in 1993 and 1995 on the ESO (European Southern Observatory) from 300 to 1000 nm. We received such nonlinear optical effects as Raman scattering of the methane bands in the Jupiter's spectrum. The vibration-rotation methane bands were considered here. The atmosphere's spectrum is formed on the different height where phisical characteristics of atmosphere are substantial different. That's why we are calculated the influence of Raman scattering effects as function of changing temperature with height in the Jupiter's atmosphere. We demonstrate that for wavelengths corresponding to Fraunhofer lines and their "ghosts", geometric albedo is observed may be used for estimating probable values of the ratios of the aerosol and gas optical thicknesses as well as the ratios of the absorbing and scattering components in the aerosol optical thickness. The ratios of the aerosol and gas optical thicknesses obtained for the Jupiter atmosphere (20±3) agree well with the estimates derived from the analysis of methane absorption bands intensity distributions over the planetary disk.

Kostogryz, N.; Morozhenko, A.; Vidmachenko, A.

294

Measurements of aerosol vertical profiles and optical properties during INDOEX 1999 using micropulse lidars  

NASA Astrophysics Data System (ADS)

Micropulse lidar (MPL) systems were used to measure aerosol properties during the Indian Ocean Experiment (INDOEX) 1999 field phase. Measurements were made from two platforms: the NOAA ship R/V Ronald H. Brown, and the Kaashidhoo Climate Observatory (KCO) in the Maldives. Sun photometers 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-1 (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-1 (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 particle soot absorption photometer 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.

2002-10-01

295

Vertical profiles, optical and microphysical properties of Saharan dust layers determined by a ship-borne lidar  

Microsoft Academic Search

A unique data set of ship-borne lidar measurements of Saharan dust layers above the Atlantic ocean has been collected aboard the research vessel Polarstern with a mobile Aerosol Raman Lidar (MARL) during the LIMPIDO-campaign in June 2000. Extended Saharan dust layers have been observed in the region between 8.5º N and 34º N in an altitude range between 2 and

F. Immler; O. Schrems

2003-01-01

296

Airborne High SPectral Resolution Lidar Aerosol Measurements during MILAGRO and TEXAQS GOMACCS.  

National Technical Information Service (NTIS)

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...

A. Clarke A. Cook C. Hostetler D. Harper J. Hair J. Redemann M. Clayton P. Russell R. Ferrare S. Burton

2007-01-01

297

General formula for the errors in aerosol properties determined from lidar measurements at a single wavelength  

NASA Astrophysics Data System (ADS)

The present study provides a general formula for the estimated error in the aerosol extinction coefficient at any range for any measured distribution of this quantity. The conducted investigation represents an extension of the error analysis for aerosol extinction coefficients performed by Klett (1981) who assumed a homogeneous atmosphere with uniform aerosol distribution. The investigation takes also into account a study done by Sasono and Nakane (1984) for a horizontal path in an atmosphere assumed to have a sinusoidally varying concentration of aerosol.

Braun, C.

1985-04-01

298

Raman lidar observations of aged Siberian and Canadian forest fire smoke in the free troposphere over Germany in 2003: Microphysical particle characterization  

Microsoft Academic Search

Dual-wavelength Raman lidar observations were regularly carried out at Leipzig (51.3°N, 12.4°E) from May to August 2003. The measurements showed that particle backscatter and extinction coefficients in the free troposphere were higher compared to values in 2000–2002. Backward dispersion modeling indicates that intense forest fires that occurred in Siberia and Canada in spring\\/summer 2003 were the main cause of these

Detlef Müller; Ina Mattis; Ulla Wandinger; Albert Ansmann; Dietrich Althausen; Andreas Stohl

2005-01-01

299

Coupling groundbased ALOMAR lidar measurements to high resolution global modelling and CALIPSO backscatter assimilation to characterize aerosol properties in the Arctic.  

NASA Astrophysics Data System (ADS)

Stratospheric aerosols are involved in cloud formation processes, especially in polar regions where thermodynamical conditions lead to polar stratospheric clouds (PSC) formation. Beside the well-known chemical effect of these clouds on polar ozone, the overall radiative impact of PSC and especially stratospheric aerosols remains unclear. Assessing the global stratospheric sulphuric load remains an issue, as measurements require both global coverage and high sensitivity. Volcanic eruptions regularly impact this aerosol budget even at high latitudes, as the stratospheric circulation takes particles throughout the dynamical barriers up to the polar regions. Around the 13th of June, 2011, the Eritrean Nabro volcano experienced a major eruption, injecting dust and particles in the upper troposphere/lower stratosphere. The transport of the newly oxydized aerosols has been reported by the CALIOP/CALIPSO spaceborne lidar. The particles produced significant optical backscatter for several months. We use a high-resolution microphysical-transport model to gain access to the small filamentary structures of the volcanic plume. CALIOP backscatters are assimilated into such a model to provide accurate constraints on the advection over time at stratospheric altitudes, where the horizontal transport is dominant. Validation is locally performed against ground-based lidar measurements acquired at the ALOMAR observatory, where microphysical aerosol properties derived from multiwavelength lidar can be compared to the model-calculated ones. Coupling the advanced detection capabilities of a stratospheric lidar to high-resolution global modelling allows for global assessment of aerosol and cloud surface area densities and volumes, which are of critical importance in ozone depletion processes.

Jumelet, J.; Keckhut, P.; Bekki, S.; Vernier, J. P.

2012-04-01

300

Exploring a geophysical process-based attribution technique for the determination of the atmospheric boundary layer depth using aerosol lidar and near-surface meteorological measurements  

NASA Astrophysics Data System (ADS)

A new objective method for the determination of the atmospheric boundary layer (ABL) depth using routine vertically pointing aerosol lidar measurements is presented. A geophysical process-based analysis is introduced to improve the attribution of the lidar-derived aerosol gradients, which is so far the most challenging part in any gradient-based technique. Using micrometeorological measurements of Obukhov length scale, both early morning and evening transition periods are determined which help separate the turbulence regimes during well-mixed convective ABL and nocturnal/stable ABL. The lidar-derived aerosol backscatter signal intensity is used to determine the hourly-averaged vertical profiles of variance of the fluctuations of particle backscatter signal providing the location of maximum turbulent mixing within the ABL; thus, obtained mean ABL depth guides the attribution by searching for the appropriate minimum of the gradients. An empirical classification of the ABL stratification patterns into three different types is proposed by determining the changes in the near-surface stability scenarios. First results using the lidar observations obtained between March and July in 2011 at SIRTA atmospheric observatory near Palaiseau (Paris suburb) in France demonstrate that the new attribution technique makes the lidar estimations of ABL depth more physically reliable under a wide spectrum of meteorological conditions. While comparing lidar and nearby radiosonde measurements of ABL depths, an excellent concordance was found with a correlation coefficient of 0.968 and 0.927 for daytime and nighttime measurements, respectively. A brief climatology of the characteristics of the ABL depth, its diurnal cycle, a detailed discussion of the morning and evening transitions are presented.

Pal, Sandip; Haeffelin, Martial; Batchvarova, Ekaterina

2013-08-01

301

Two-component wind fields from scanning aerosol lidar and motion estimation algorithms  

NASA Astrophysics Data System (ADS)

We report on the implementation and testing of a new wavelet-based motion estimation algorithm to estimate horizontal vector wind fields in real-time from horizontally-scanning elastic backscatter lidar data, and new experimental results from field work conducted in Chico, California, during the summer of 2013. We also highlight some limitations of a traditional cross-correlation method and compare the results of the wavelet-based method with those from the cross-correlation method and wind measurements from a Doppler lidar.

Mayor, Shane D.; Dérian, Pierre; Mauzey, Christopher F.; Hamada, Masaki

2013-09-01

302

A method for retrieving vertical distribution of aerosol mass concentration in atmosphere from results of lidar sensing at Nd:YAG laser wavelengths  

NASA Astrophysics Data System (ADS)

A method for retrieving the vertical profiles of atmospheric aerosol concentration from the results of lidar sensing at Ng:YAG laser wavelengths is developed based on the found multiple regressions between the optical location characteristics of aerosol at wavelengths of 0.355, 0.532, and 1.064 nm, as well as between the aerosol backscattering coefficient at these wavelengths and the concentration of aerosol particles. The method does not require solving ill-posed inverse problems and minimizes the use of a priori information. The reliability and generality of regressions obtained are confirmed by their good agreement with the AERO-NET data. The method efficiency is demonstrated by numerical experiments on retrieving profiles of back-scattering coefficients and concentration that corresponds to different optical models of aerosol.

Lisenko, S. A.; Kugeiko, M. M.

2011-03-01

303

Lidars as an operational tool for meteorology and advanced atmospheric research  

NASA Astrophysics Data System (ADS)

The talk will present the concept and observation results of three advanced lidar systems developed recently at the Swiss federal Institute of Technology- Lausanne (EPFL) Switzerland. Two of the systems are Raman lidars for simultaneous water vapor, temperature and aerosol observations and the third one is an ozone UV DIAL system. The Ranan lidars use vibrational water vapor and nitrogen signals to derive water vapor mixing ratio and temperature, aerosol extinction and backscatter are measured using pure-rotational Raman and elastic signals. The first Raman lidar (RALMO) is a fully automated, water vapor /temperature/aerosol lidar developed for operational use by the Swiss meteorological office (MeteoSiss). The lidar supplies water vapor mixing ratio and temperature plus aerosol extinction and backscatter coefficients at 355 nm. The operational range of the lidar is 100-7000 m (night time) and 100- 5000 m (daytime) with time resolution of 30 min. The spatial resolution varies with height from 25 to 300 m in order to maintain the maximum measurement error of 10%. The system is designed to provide long-term database with minimal instrument-induced variations in time of the measured parameters. The lidar has been in regular operation in the main aerological station of Meteoswiss- Payerne since September 2008. The second Raman lidar is a new generation, solar-blind system with an operational range 10-500 m and high spatial (1.5 m) and temporal (1 s) resolutions designed for simultaneous humidity, temperature, and aerosol measurements in the lower atmosphere. To maintain the measurement accuracy while operating with fixed spatial and temporal resolution, the receiver is designed to provide lower than ten dynamic range of the signals within the distance range of the lidar. The lidar has 360° azimuth and 240°elevation scanning ability. The lidar was used in two field campaigns aiming to study the structure of the lower atmosphere over complex terrains and, in particular, to advance our understanding of turbulent blending mechanisms in the unstable atmosphere. The third lidar is an ozone UV DIAL system designed for studies of the upper troposphere, lower stratosphere ozone exchange processes. The lidar is based on a commercial fourth harmonic Nd:YAG laser. The DIAL wavelengths (284 and 304 nm) are produced by stimulated Raman conversion in high pressure nitrogen. A 76 cm in diameter Cassegrein telescope is used in the receiver and the spectral separation of the signals is carried out by an imaging-grating based polychromator. The operational distance of the lidar is 6000 -12000 m ASL with a statistical error lower than 10%. The lidar is deployed at the High Altitude Research Station Jungfraujoch at 3600 m altitude in the Swiss Alps. The lidar accuracy was verified by comparison to profiles taken by ECC balloon-borne sondes launched by Meteoswiss from Payerne. The lidar has been in use from September 2008 and since that time several stratospheric intrusions and cases of intercontinental transport and transport from the atmospheric boundary layer have been observed.

Simeonov, Valentin; Dinoev, Todor; Serikov, Ilya; Froidevaux, Martin; Bartlome, Marcel; Calpini, Bertrand; Bobrovnikov, Sergei; Ristori, Pablo; van den Bergh, Hubert; Parlange, Marc; Archinov, Yury

2010-05-01

304

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

NASA Astrophysics Data System (ADS)

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 unique confocal cavity for optically filtering the aerosol and molecular returns is presented. An injection seeded pulsed Nd:YAG laser with a fundamental and frequency doubled output is used as the laser transmitter for the HSRL. A small portion of fiber coupled injection seeded signal at 1064 nm is split before the laser oscillator and, after modulation using an acousto-optic modulator, is used to produce a discriminating signal for locking a confocal cavity that is resonant at the 1064 and 532 nm wavelengths to the injection seeded source. Light scattered in the atmosphere is collected using a commercial telescope. After the telescope, the 1064 nm light is split from the 532 nm light using a dielectric mirror with the 1064 nm light monitored using a PMT. The 532 nm light is launched into a multimode fiber. The output from the fiber is next incident on a beamsplitter with part of the light sent to a PMT to monitor the total return for the 532 nm channel. The light that passes through the beamsplitter is mode matched into a confocal optical cavity that allows the light scattered by the atmospheric aerosols to be transmitted while the light scattered from the atmospheric molecules is reflected. The transmitted light from the aerosol scattering is incident on a PMT while the reflected molecular signal is incident on a PMT. The transmission of the confocal cavity is monitored before and after the data collection using a continuous wave frequency doubled Nd:YAG laser that is fiber coupled. Data is collected and processed in the following manner. Each of the four voltage signals from the PMT’s are monitored using a high speed A/D card. The inversion of the 1064 nm return signal is completed using the Fernald inversion technique with the additional constraint of the aerosol optical depth. The HSRL 532 nm signal is inverted using a Rayleigh backscatter model along with the inversion techniques described by Shipley et al. (Applied Optics, V22, N23, 3716-3724, 1983) and Sroga et al. (Applied Optics, V22, N23, 3725-3732, 1983). This presentation will focus on the design of the confocal optical filter, the locking of the confocal optical filter to the laser transmitter, and the performance of the high spectral resolution channel at 532 nm. Data will be presented showing the molecular returns, the aerosol returns and the range resolved lidar ratio.

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

2010-12-01

305

Airborne sunphotometer PLASMA: concept, measurements, comparison of aerosol extinction vertical profile with lidar  

NASA Astrophysics Data System (ADS)

A 15-channel airborne sun tracking photometer has been developed. The instrument provides aerosol optical depths over a wide spectral range (0.34-2.25 ?m) with an accuracy of ?AOD from 0.005 to 0.01. Doing measurements at different altitudes allow us to derive the aerosol extinction vertical profile. Thanks to the wide spectral range of the instrument, information on the aerosol size distribution along the vertical is also available.

Karol, Y.; Tanré, D.; Goloub, P.; Vervaerde, C.; Balois, J. Y.; Blarel, L.; Podvin, T.; Mortier, A.; Chaikovsky, A.

2012-09-01

306

Airborne sun photometer PLASMA: concept, measurements, comparison of aerosol extinction vertical profile with lidar  

NASA Astrophysics Data System (ADS)

A 15-channel airborne sun-tracking photometer has been developed. The instrument provides aerosol optical depths over a wide spectral range (0.34-2.25 ?m) with an accuracy (?AOD) of approximately 0.01. Taking measurements at different altitudes allow us to derive the aerosol extinction vertical profile. Thanks to the wide spectral range of the instrument, information on the aerosol size distribution along the vertical is also available.

Karol, Y.; Tanré, D.; Goloub, P.; Vervaerde, C.; Balois, J. Y.; Blarel, L.; Podvin, T.; Mortier, A.; Chaikovsky, A.

2013-09-01

307

Stand-off detection of plant-produced volatile organic compounds using short-range Raman LIDAR  

NASA Astrophysics Data System (ADS)

Several plant species release volatile organic compounds (VOCs) when under stresses such as herbivore feeding attack. The release of these plant-produced VOCs (i.e. terpenes) triggers the release of active biochemical defenses, which target the attacker. In some cases, the VOCs send cues to nearby carnivorous predators to attract them to the feeding herbivore. Volatile compounds are released both locally by damaged leaves and systemically by the rest of the plant. These compounds are released in large quantities, which facilitate detection of pests in the field by parasitoids. Detecting the plant"s VOC emissions as a function of various parameters (e.g. ambient temperature, atmospheric nitrogen levels, etc.) is essential to designing effective biological control systems. In addition these VOC releases may serve as early warning indicator of chemo-bio attacks. By combining Raman spectroscopy techniques with Laser Remote Sensing (LIDAR) systems, we are developing a Standoff detection system. Initial results indicate that is it possible to detect and differentiate between various terpenes, plant species, and other chemical compounds at distances greater than 12 meters. Currently, the system uses the 2nd harmonic of a Nd:YAG; however plans are underway to improve the Raman signal by moving the illumination wavelength into the solar-blind UV region. We report on our initial efforts of designing and characterizing this in a laboratory proof of concept system. We envision that this effort will lead to the design of a portable field-deployable system to rapidly characterize, with a high spatial resolution, large crops and other fields.

Johnson, Lewis; Barnett, Cleon; Brown, Christopher; Crawford, Devron; Tumlinson, James

2004-03-01

308

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

SciTech Connect

Project goals: (1) Use the routine surface and airborne measurements at the ARM SGP site, and the routine surface measurements at the NSA site, to continue our evaluations of model aerosol simulations; (2) Determine the degree to which the Raman lidar measurements of water vapor and aerosol scattering and extinction can be used to remotely characterize the aerosol humidification factor; (3) Use the high temporal resolution CARL data to examine how aerosol properties vary near clouds; and (4) Use the high temporal resolution CARL and Atmospheric Emitted Radiance Interferometer (AERI) data to quantify entrainment in optically thin continental cumulus clouds.

Richard A. Ferrare; David D. Turner

2011-09-01

309

New Lidar Remote Sensing Capabilities at the Atmospheric Radiation Measurement Climate Research Facilities (Invited)  

NASA Astrophysics Data System (ADS)

In 2009 the US Department of Energy’s Atmospheric Radiation Measurement Climate Research Facility (ACRF) was awarded funds through the American Recovery and Reinvestment Act (ARRA) for instrument acquisitions and upgrades. A significant portion of that award is being used to acquire new advanced lidar systems for all of the ACRF sites. Efforts are currently underway to develop the following systems: 1) one Raman lidar for installation at the Tropical West Pacific (TWP) site in Darwin, Australia; 2) two High Spectral Resolution Lidars (HSRL) for deployment at the North Slope of Alaska (NSA) site in Barrow, and with the second mobile facility (AMF2); 3) three coherent Doppler lidars for deployment at the Southern Great Plains (SGP) site in Oklahoma, TWP-Darwin, and with the first mobile facility (AMF1). Additionally, the following systems are being upgraded: 1) laser ceilometers at SGP, TWP, NSA, and mobile facilities; 2) Micropulse Lidars (MPL) at SGP, TWP, NSA, and mobile facilities; 3) the existing Raman lidar at SGP. The new Raman lidar at TWP-Darwin will provide time and height resolved measurements of water vapor mixing ratio, temperature, aerosol extinction, backscatter, and depolarization. The design of this system will closely follow that of the existing Raman lidar at SGP. The SGP Raman system has been operational for well over 10 years and is well proven. Over the years a number of upgrades have been incorporated that have greatly improved performance of the system. Examples include simultaneous photon counting and analog detection electronics, the addition of two rotational Raman channels for temperature profiling, and continuous active boresight alignment. The new system at Darwin will incorporate these features as well. The HSRL systems will improve cloud and aerosol remote sensing at NSA and AMF2 by enabling a direct measurement of extinction. Extinction profiles at these sites are currently being generated as PI data products from MPL data. The HSRL measurement technique obviates the need to assume a constant (or prescribed) backscatter-to-extinction ratio, as is currently the case when using MPL data. The Doppler lidars will help fill a long standing measurement gap within ACRF. These systems will operate in a vertically staring mode to acquire long-term measurements of clear-air vertical velocities in the lower troposphere. These data will be used to investigate statistics of updrafts and downdrafts, and the vertical transport of aerosols. This presentation will discuss the expected performance characteristics of the new ACRF lidar systems and the impact that the new systems are expected to have on the science.

Newsom, R.; Comstock, J. M.; Turner, D. D.; Ferrare, R. A.; Flynn, C.; Goldsmith, J.; Morris, V. R.; Coulter, R.

2009-12-01

310

Application of randomly oriented spheroids for retrieval of dust particle parameters from multiwavelength lidar measurements  

NASA Astrophysics Data System (ADS)

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

Veselovskii, I.; Dubovik, O.; Kolgotin, A.; Lapyonok, T.; di Girolamo, P.; Summa, D.; Whiteman, D. N.; Mishchenko, M.; Tanré, D.

2010-11-01

311

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

Microsoft Academic Search

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.

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

2009-01-01

312

Comparison of optical and microphysical properties of pure Saharan mineral dust observed with AERONET Sun photometer, Raman lidar, and in situ instruments during SAMUM 2006  

NASA Astrophysics Data System (ADS)

The Saharan Mineral Dust Experiment (SAMUM) 2006, Morocco, aimed at the characterization of optical, physical, and radiative properties of Saharan dust. AERONET Sun photometer, several lidars (Raman and high-spectral-resolution instruments), and airborne and ground-based in situ instruments provided us with a comprehensive set of data on particle-shape dependent and particle-shape independent dust properties. We compare 4 measurement days in detail, and we carry out a statistical analysis for some of the inferred data products for the complete measurement period. Particle size distributions and complex refractive indices inferred from the Sun photometer observations and measured in situ aboard a research aircraft show systematic differences. We find differences in the wavelength-dependence of single-scattering albedo, compared to light-scattering computations that use data from SOAP (spectral optical absorption photometer). AERONET data products of particle size distribution, complex refractive index, and axis ratios were used to compute particle extinction-to-backscatter (lidar) ratios and linear particle depolarization ratios. We find differences for these parameters to lidar measurements of lidar ratio and particle depolarization ratio. Differences particularly exist at 355 nm, which may be the result of differences of the wavelength-dependent complex refractive index that is inferred by the methods employed in this field campaign. We discuss various error sources that may lead to the observed differences.

Müller, D.; Lee, K.-H.; Gasteiger, J.; Tesche, M.; Weinzierl, B.; Kandler, K.; Müller, T.; Toledano, C.; Otto, S.; Althausen, D.; Ansmann, A.

2012-04-01

313

Lidar measurement of the stratospheric aerosol layer at Syowa Station (69.00 deg S, 39.35 deg E), Antarctica  

NASA Astrophysics Data System (ADS)

Polar stratospheric aerosols (PSA) were measured over Antarctica in 1983 using ground-based lidar. A decrease in stratospheric temperature was correlated with a rise in extinction in the stratosphere. The temperature decrease was associated with an increase in stratospheric particulate matter, which may not have been the growth of ice crystals. The growth observed was commensurate with previous reports of the formation of polar stratospheric clouds. Good characterization of the PSA is asserted to depend on the acquisition of data on the H2O vapor, H2SO4 content, chemical composition and aerosol particle sizes in the PSA.

Iwasaka, Y.

1985-04-01

314

Understanding hygroscopic growth and phase transformation of aerosols using single particle Raman spectroscopy in an electrodynamic balance.  

PubMed

Hygroscopic growth is one of the most fundamental properties of atmospheric aerosols. By absorbing or evaporating water, an aerosol particle changes its size, morphology, phase, chemical composition and reactivity and other parameters such as its refractive index. These changes affect the fate and the environmental impacts of atmospheric aerosols, including global climate change. The ElectroDynamic Balance (EDB) has been widely accepted as a unique tool for measuring hygroscopic properties and for investigating phase transformation of aerosols via single particle levitation. Coupled with Raman spectroscopy, an EDB/Raman system is a powerful tool that can be used to investigate both physical and chemical changes associated with the hygroscopic properties of individually levitated particles under controlled environments. In this paper, we report the use of an EDB/Raman system to investigate (1) contact ion pairs formation in supersaturated magnesium sulfate solutions; (2) phase transformation in ammonium nitrate/ammonium sulfate mixed particles; (3) hygroscopicity of organically coated inorganic aerosols; and (4) heterogeneous reactions altering the hygroscopicity of organic aerosols. PMID:18214108

Lee, Alex K Y; Ling, T Y; Chan, Chak K

2008-01-01

315

Raman Spectroscopy Techniques for the Detection of Biological Samples in Suspensions and as Aerosol Particles: A Review  

NASA Astrophysics Data System (ADS)

This article reviews current scientific literature focusing on Raman spectroscopy modalities that have been successfully applied to the detection of biological samples in aqueous suspensions and in aerosols. Normal Raman, surface enhanced Raman scattering, coherent anti-stokes Raman scattering, resonance Raman and UV-Raman spectropies, allow the detection of biological samples in situ in the near field and as well as in the far field at standoff distances. Applications span from fundamental studies to applied research in areas of defense and security and in monitoring of environmental pollution. A primary focus has been placed on biological samples including bacteria, pollen, virus, and biological contents in these specimens, in suspensions, and in aerosols. Several Raman spectroscopy studies have been reviewed to show how various modalities can achieve detection in these biosystems. Current data generated by our group is also included. Necessary parameters used to accomplish the detection and data analysis, which could also be used to interpret the results and to render the methodologies robust and reliable, are discussed.

Félix-Rivera, Hilsamar; Hernández-Rivera, Samuel P.

2012-03-01

316

Spaceborne lidar system for measurements of atmospheric water vapor and aerosols  

NASA Astrophysics Data System (ADS)

The inclusion of a differential absorption lidar (DIAL) system as part of the NASA Earth Observing System (EOS) is proposed. Functioning at 720 nm, the DIAL could provide atmospheric water vapor profiles in the troposphere and stratosphere, and provide data for characterizing the physical properties of clouds. The use of frequency doubling of the laser could also open a window on the 355 nm region, and thereby molecular density and temperature profiles. The date would be of use in studies of the global hydrological cycle, the global radiation balance, climate, meteorology, and atmospheric structure and transport phenomena.

Browell, E. V.; Ismail, S.; McCormick, M. P.; Swissler, T. J.

1985-10-01

317

Raman shifter optimized for lidar at a 1.5 microm wavelength.  

PubMed

A Raman shifter is optimized for generating high-energy laser pulses at a 1.54 microm wavelength. A forward-scattering design is described, including details of the multiple pass and nonfocused optical design, Stokes injection seeding, and internal gas recirculation. First-Stokes conversion efficiencies up to 43%--equivalent to 62% photon conversion efficiency--were measured. Experimental results show output average power in excess of 17.5 W, pulse energies of 350 mJ at 50 Hz, with good beam quality (M2<6). Narrow bandwidth and tunable output is produced when pumping with a single longitudinal mode Nd:YAG laser and seeding the process with a Stokes wavelength narrowband laser diode. PMID:17514248

Spuler, Scott M; Mayor, Shane D

2007-05-20

318

Aerosol retrieval from two-wavelength backscatter and one-wavelength polarization lidar measurement taken during the MR01K02 cruise of the R\\/V Mirai and evaluation of a global aerosol transport model  

Microsoft Academic Search

Using two-wavelength lidar with one-wavelength depolarization measurement installed on the research vessel Mirai, we retrieved vertical distributions of extinction coefficients of water-soluble, sea-salt, and dust particles at 532 nm. In the retrieval, the mode radii, standard deviations, and refractive indexes for each aerosol component are prescribed; the retrieval uncertainties due to spherical assumption in our dust model are estimated to

Tomoaki Nishizawa; Hajime Okamoto; Toshihiko Takemura; Nobuo Sugimoto; Ichiro Matsui; Atsushi Shimizu

2008-01-01

319

Evaluation of the Lidar/Radiometer Inversion Code (LIRIC) to determine microphysical properties of volcanic and desert dust  

NASA Astrophysics Data System (ADS)

The Lidar/Radiometer Inversion Code (LIRIC) combines the multiwavelength lidar technique with sun-sky photometry and allows us to retrieve vertical profiles of particle optical and microphysical properties, separately for fine-mode and coarse-mode particles. After a brief presentation of the theoretical background, we evaluate the potential of LIRIC to retrieve the optical and microphysical properties of irregularly shaped dust particles. The method is applied to two very different aerosol scenarios, a strong Saharan dust outbreak towards central Europe and an Eyjafjallajökull volcanic dust event. LIRIC profiles of particle volume and mass concentrations are compared with results obtained with the polarization-lidar-based POLIPHON method. LIRIC profiles of optical properties such as particle backscatter coefficients, lidar ratio, Ångström exponent, and particle depolarization ratio are compared with direct Raman lidar observations. Good agreement between the different results are found for most of the retrieval products.

Wagner, J.; Ansmann, A.; Wandinger, U.; Seifert, P.; Schwarz, A.; Tesche, M.; Chaikovsky, A.; Dubovik, O.

2013-01-01

320

Calculation of aerosol backscatter from airborne continuous wave focused CO sub 2 Doppler lidar measurements. 2. Algorithm performance  

SciTech Connect

The performance of an algorithm to calculate aerosol backscatter coefficients, from measurements with an airborne continuous wave focused CO{sub 2} Doppler lidar, is described relative to flight hardware settings and operating characteristics, and theoretical considerations. The algorithm (described in paper 1) is used to analyze measurements by the Laser True Airspeed System (LATAS), operated by the Royal Signals and Radar Establishment (RSRE) and Royal Aircraft Establishment (RAE), United Kingdom. Under optimum signal conditions, backscatter signals are located unambiguously and the backscatter coefficients are accurately determined. Under marginal or subthreshold conditions, with a degraded system sensitivity, false alarms (mistaking noise for signal) occur. Parametric studies show that the false alarm rate under these conditions depends on the search window size and the signal-to-noise ratio (SNR) threshold for valid signals. Carefully selected diagnostic parameters are used to estimate the combined sensitivity of the flight hardware system and algorithm. Less than 1% of backscatter measurements for flights over approximately 5 years have been found to be below the measurement sensitivity when the LATAS flight hardware controls were set for optimum sensitivity.

Rothermel, J. (NASA Marshall Space Flight Center, Huntsville, AL (USA)); Bowdle, D.A. (Univ. of Alabama, Huntsville (USA)); Vaughan, J.M. (Royal Signals and Radar Establishment, Worcestshire (England))

1991-03-20

321

Evaluation of the Lidar/Radiometer Inversion Code (LIRIC) to determine microphysical properties of volcanic and desert dust  

NASA Astrophysics Data System (ADS)

The Lidar/Radiometer Inversion Code (LIRIC) combines the multiwavelength lidar technique with sun/sky photometry and allows us to retrieve vertical profiles of particle optical and microphysical properties separately for fine-mode and coarse-mode particles. After a brief presentation of the theoretical background, we evaluate the potential of LIRIC to retrieve the optical and microphysical properties of irregularly shaped dust particles. The method is applied to two very different aerosol scenarios: a strong Saharan dust outbreak towards central Europe and an Eyjafjallajökull volcanic dust event. LIRIC profiles of particle mass concentrations for the coarse-mode as well as for the non-spherical particle fraction are compared with results for the non-spherical particle fraction as obtained with the polarization-lidar-based POLIPHON method. Similar comparisons for fine-mode and spherical particle fractions are presented also. Acceptable agreement between the different dust mass concentration profiles is obtained. LIRIC profiles of optical properties such as particle backscatter coefficient, lidar ratio, Ångström exponent, and particle depolarization ratio are compared with direct Raman lidar observations. Systematic deviations between the LIRIC retrieval products and the Raman lidar measurements of the desert dust lidar ratio, depolarization ratio, and spectral dependencies of particle backscatter and lidar ratio point to the applied spheroidal-particle model as main source for these uncertainties in the LIRIC results.

Wagner, J.; Ansmann, A.; Wandinger, U.; Seifert, P.; Schwarz, A.; Tesche, M.; Chaikovsky, A.; Dubovik, O.

2013-07-01

322

Aerosol properties over Interior Alaska from lidar, DRUM Impactor sampler, and OPC-sonde measurements and their meteorological context during ARCTAS-A, April 2008  

NASA Astrophysics Data System (ADS)

Aerosol loading over Interior Alaska displays a strong seasonality, with pristine conditions generally prevailing during winter months. Long term aerosol research from the University of Alaska Fairbanks indicates that the period around April typically marks the beginning of the transition from winter to summer conditions. In April 2008, the NASA-sponsored "Arctic Research of the Composition of the Troposphere from Aircraft and Satellites" (ARCTAS) field campaign was conducted to analyze incursions of aerosols transported over Alaska and the Canadian North. In and around Fairbanks, Alaska, data concerning aerosol characteristics were gathered by polarization (0.693 ?m) lidar, DRUM Impactor sampler, and balloon-borne optical particle counter. These data provide information on the vertical distribution and type of aerosol, their size distributions, the chemical nature of aerosol observed at the surface, and timing of aerosol loading. A detailed synoptic analysis placed these observations into their transport and source-region context. Evidence suggests four major aerosol loading periods in the 25 March-30 April 2008 timeframe: a period during which typical Arctic haze conditions prevailed, several days of extremely clear conditions, rapid onset of a period dominated by Asian dust with some smoke, and a period dominated by Siberian wildfire smoke. A focused case study analysis conducted on 19 April 2008 using a balloon-borne optical particle counter suggests that, on this day, the majority of the suspended particulate matter consisted of coarse mode desiccated aerosol having undergone long-range transport. Backtrack trajectory analysis suggests aged Siberian wildfire smoke. In the last week of April, concentrations gradually decreased as synoptic conditions shifted away from favoring transport to Alaska. An important result is a strong suggestion of an Asian dust incursion in mid-April that was not well identified in other ARCTAS measurements. The lidar and OPC-sonde unambiguously discern aerosols height stratification patterns indicative of long range transport. Identification of a dust component is suggested by DRUM sampler results, which indicate crustal species, and supported by synoptic and trajectory analysis, which indicates both a source-region lifting event and appropriate air-mass pathways.

Atkinson, D. E.; Sassen, K.; Hayashi, M.; Cahill, C. F.; Shaw, G.; Harrigan, D.; Fuelberg, H.

2013-02-01

323

Aerosol retrieval from two-wavelength backscatter and one-wavelength polarization lidar measurement taken during the MR01K02 cruise of the R/V Mirai and evaluation of a global aerosol transport model  

NASA Astrophysics Data System (ADS)

Using two-wavelength lidar with one-wavelength depolarization measurement installed on the research vessel Mirai, we retrieved vertical distributions of extinction coefficients of water-soluble, sea-salt, and dust particles at 532 nm. In the retrieval, the mode radii, standard deviations, and refractive indexes for each aerosol component are prescribed; the retrieval uncertainties due to spherical assumption in our dust model are estimated to be 30-50%. The ship-based measurements were conducted in the western Pacific Ocean near Japan from 14 to 27 May 2001. For the analysis, we applied two-wavelength lidar algorithms to the three-channel lidar data, i.e., for signal strengths at 532 and 1064 nm and the total depolarization ratio at 532 nm. Water-soluble and sea-salt particles occurred below 1 km, whereas air masses dominated by water-soluble and dust particles were sometimes found above 1 km. We also investigated the correlation of sea-salt extinction coefficient with surface wind velocity for various altitudes. A positive correlation was found at low altitude, but no correlation was indicated at high altitude. We also compared the extinction coefficients of water-soluble and sea-salt particles directly under cloud bottom with those in clear-sky. Below clouds, the extinction coefficients of water-soluble and sea-salt particles were 1.6 and 1.4 times larger, respectively, than those in clear sky; this could be explained by hygroscopic growth using Hänel theory. Finally, we evaluated the global aerosol transport model SPRINTARS using the retrieved aerosol properties and measured lidar signals. The model underestimated sea salt and overestimated dust, although the general patterns agreed with the observed patterns.

Nishizawa, Tomoaki; Okamoto, Hajime; Takemura, Toshihiko; Sugimoto, Nobuo; Matsui, Ichiro; Shimizu, Atsushi

2008-11-01

324

Description and evaluation of a tropospheric ozone lidar implemented on an existing lidar in the southern subtropics.  

PubMed

Rayleigh-Mie lidar measurements of stratospheric temperature and aerosol profiles have been carried out at Reunion Island (southern tropics) since 1993. Since June 1998, an operational extension of the system is permitting additional measurements of tropospheric ozone to be made by differential absorption lidar. The emission wavelengths (289 and 316 nm) are obtained by stimulated Raman shifting of the fourth harmonic of a Nd:YAG laser in a high-pressure deuterium cell. A mosaic of four parabolic mirrors collects the backscattered signal, and the transmission is processed by the multiple fiber collector method. The altitude range of ozone profiles obtained with this system is 3¿17 km. Technical details of this lidar system working in the southern tropics, comparisons of ozone lidar profiles with radiosondes, and scientific perspectives are presented. The significant lack of tropospheric ozone measurements in the tropical and equatorial regions, the particular scientific interest in these regions, and the altitude range of the ozone measurements to 16¿17 km make this lidar supplement useful and its adaptation technically conceivable at many Rayleigh-Mie lidar stations. PMID:18324220

Baray, J L; Leveau, J; Porteneuve, J; Ancellet, G; Keckhut, P; Posny, F; Baldy, S

1999-11-20

325

Initial analysis from a lidar observation campaign of sugar cane fires in the central and western portion of the São Paulo State, Brazil  

NASA Astrophysics Data System (ADS)

The central and western portion of the Sao Paulo State has large areas of sugar cane plantations, and due to the growing demand for biofuels, the production is increasing every year. During the harvest period some plantation areas are burnt a few hours before the manual cutting, causing significant quantities of biomass burning aerosol to be injected into the atmosphere. During August 2010, a field campaign has been carried out in Ourinhos, situated in the south-western region of Sao Paulo State. A 2-channel Raman Lidar system and two meteorological S-Band Doppler Radars are used to indentify and quantify the biomass burning plumes. In addiction, CALIPSO Satellite observations were used to compare the aerosol optical properties detected in that region with those retrieved by Raman Lidar system. Although the campaign yielded 30 days of measurements, this paper will be focusing only one case study, when aerosols released from nearby sugar cane fires were detected by the Lidar system during a CALIPSO overpass. The meteorological radar, installed in Bauru, approximately 110 km northeast from the experimental site, had recorded "echoes" (dense smoke comprising aerosols) from several fires occurring close to the Raman Lidar system, which also detected an intense load of aerosol in the atmosphere. HYSPLIT model forward trajectories presented a strong indication that both instruments have measured the same air masss parcels, corroborated with the Lidar Ratio values from the 532 nm elastic and 607 nm Raman N2 channel analyses and data retrieved from CALIPSO have indicated the predominance of aerosol from biomass burning sources.

da Silva Lopes, Fábio Juliano; Held, Gerhard; Nakaema, Walter M.; Rodrigues, Patricia F.; Bassan, Jose M.; Landulfo, Eduardo

2011-10-01

326

Statistical considerations on the Raman inversion algorithm: data inversion and error assessment  

NASA Astrophysics Data System (ADS)

Lidar (radar laser) systems take advantage of the relatively strong interaction between laser light and aerosol/molecular species in the atmosphere. The inversion of optical atmospheric parameters is of prime concern in the fields of environmental and meteorological modelling and has been (and still is) under research study for the past four decades. Within the framework of EARLINET (European Aerosol LIdar NETwork), independent inversions of the atmospheric optical extinction and backscatter profiles (and thus, of the lidar ratio, as well) have been possible by assimilating elastic-Raman data into Ansmann et al."s algorithm [the term "elastic-Raman" caters for the combination of one elastic lidar channel (i.e., no wavelength shift in reception) with an inelastic Raman one (i.e., wavelength shifted)]. In this work, an overview of this operative method is presented under noisy scenes along with a novel formulation of the algorithm statistical performance in terms of the retrieved-extinction mean-squared error (MSE). The statistical error due to signal detection (Poisson) is the main error source considered while systematic and operational-induced errors are neglected. In contrast to Montercarlo and error propagation formulae, often used as customary approaches in lidar error inversion assessment, the statistical approach presented here analytically quantifies the range-dependent MSE performance as a function of the estimated signal-to-noise ratio of the Raman channel, thus, becoming a straightforward general formulation of algorithm errorbars.

Rocadenbosch, Francesc; Sicard, Michael; Ansmann, Albert; Wandinger, Ulla; Matthias, Volker; Pappalardo, Gelsomina; Bockmann, Christine; Comeron, Adolfo; Rodriguez, Alejandro; Munoz, Constantino; Lopez, Miguel A.; Garcia, David

2004-01-01

327

Initial High Spectral Resolution Lidar Results From the Cumulus Humilis Aerosol Processing Study (CHAPS) and Cloud and Land Surface Interaction Campaign (CLASIC)  

NASA Astrophysics Data System (ADS)

The Cumulus Humilis Aerosol Processing Study (CHAPS) field campaign, sponsored by the Department of Energy Atmospheric Science Program (ASP), and the Cloud and Land Surface Interaction Campaign (CLASIC), sponsored by the DOE Atmospheric Radiation Measurement (ARM) Program, were performed during June 2007, with the respective goals of studying aerosol and cloud interactions and advancing the understanding of how land surface processes influence cumulus convection in the Oklahoma City region. The campaigns involved several coordinated air- and ground-based remote and in situ sensors, including, among others, the NASA Langley Research Center (LaRC) Airborne High Spectral Resolution Lidar (HSRL) aboard the NASA King Air B-200 aircraft, instruments located at the DOE Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) Climate Research Facility (CRF), and instruments aboard the DOE Gulfstream-1, the Center for Interdisciplinary Remotely-Piloted Aircraft Studies (CIRPAS) Twin Otter, and the DOE ARM Cessna 206 aircraft. The aircraft were flown in coordinated patterns over common ground tracks on several occasions, some of which involved passing over the SGP CRF and/or were coordinated with overpasses from satellites in the A-Train constellation. These coordinated measurements enabled coincident observations of aerosol properties near clouds, facilitating analyses of cloud and aerosol interactions and properties across changing atmospheric conditions. Over the course of the CHAPS-CLASIC mission, the NASA LaRC Airborne HSRL instrument flew 22 flights obtaining nearly 70 hours of observations. The Airborne HSRL directly measured aerosol backscatter and depolarization at wavelengths of 532 nm and 1064 nm, and aerosol extinction at 532 nm, allowing for calibrated computation of the aerosol extinction-to-backscatter ratio, wavelength dependence, and depolarization ratio profiles extending from near the surface to about 8 km above ground level. An overview of the NASA LaRC HSRL mission, as well as preliminary results from the HSRL during the CLASIC/CHAPS field campaign will be presented.

Obland, M. D.; Cook, A. L.; Ferrare, R. A.; Hair, J. W.; Harper, D. B.; Hostetler, C. A.; Rogers, R. R.

2007-12-01

328

Temperature, NLC/aerosol and metal observations by mobile potassium/iron Doppler lidar at Spitsbergen, 78° N and Andoya, 69° N  

NASA Astrophysics Data System (ADS)

Between 2001 and 2003 the mobile K-lidar has measured temperature, potassium density and NLC at Spitsbergen, 78N. The measurements show a cold summer mesopause with mean tem-peratures below 120 K at 89/90 km altitude and a strong influence of ice particles on the metal layer. NLC has been observed during two summer seasons (2001 and 2003), giving mean values on brightness, occurrence rate and altitude. A more recent analysis indicates a strong influence of tides on the altitude and brightness of NLC at 78 N. Measurements in summer at polar region must be performed at daylight. The solar radiation at daylight causes a strong increase of the background by many orders of magnitudes. By narrow band filtering alone the back-ground cannot be rejected completely and is still many orders of magnitude larger compared to night time observations. For this reason we have build a new type of Doppler resonance lidar, the mobile Fe-lidar, which measures Doppler temperature, vertical wind and iron density at daylight with negligible background at 386 nm. Simultaneously background free measurements of NLC and stratospheric aerosols are observed at 772 nm. By applying spectral filtering with a bandwidth 100 times smaller than the Doppler width of Rayleigh scattering NLC/aerosol are distinguished from Rayleigh scattering. First routine measurements have been performed at Andoya, 69 N from July 2008 to June 2009. Approx. seasonal coverage of the measurements has been achieved by remote operation of the lidar. We show that the Fe-lidar temperatures at 69 N are in good agreement with earlier rocket borne observations at the same locations by Lübken, JGR 1999. The summer mesopause is at 89 km altitude with temperatures below 130 K. Strong gravity wave activity and a remarkable tide have been observed in summer season. The lower edge of the iron layer is strongly influenced by sunlight showing a different behaviour than observed for any other metal so far. The major stratospheric warming in Januar 2009 has strongly influences the metal layer and the average temperature was approx. 50 K lower as on average for January.

Höffner, Josef; Lautenbach, Jens; Lübken, Franz-Josef

329

Strong Updraft at a Sea-Breeze Front and Associated Vertical Transport of Near-Surface Dense Aerosol Observed by Doppler Lidar and Ceilometer  

NASA Astrophysics Data System (ADS)

To study the wind field within the atmospheric boundary layer over the Tokyo metropolitan area, Doppler lidar observations were made 45 km north of Sagami Bay and 30 km west of Tokyo Bay, from 14 May to 15 June 2008. Doppler lidar on 27 May 2008 observed the vertical and horizontal wind structure of a well-developed sea-breeze front (SBF) penetrating from Sagami Bay. At the SBF, a strong updraft (maximum w approximately equal to 5 m s-1) was formed with a horizontal scale of about 500 m and vertical scale of 2 km. The spatial relationship between the strong updraft over the nose of the SBF and prefrontal thermal suggests that the strong updraft was triggered by interaction between the SBF and the thermal. After the updraft commenced, a collocated ceilometer observed an intense aerosol backscatter up to 2 km above ground level. The observational results suggest that the near-surface denser aerosols trapped in the head region of the SBF escaped from the nose of the SBF and were then vertically transported up to the mixing height by the strong updraft at the SBF. This implies that these phenomena occurred not continuously but intermittently. The interaction situations between the SBF and prefrontal thermal can affect the wind structure at the SBF and the regional air quality.

Iwai, Hironori; Murayama, Yasuhiro; Ishii, Shoken; Mizutani, Kohei; Ohno, Yuichi; Hashiguchi, Taichiro

2011-10-01

330

Routine measurements of aerosol extinction profiles by the ARM program and their validation  

NASA Astrophysics Data System (ADS)

The vertical profile of aerosol extinction is needed as input for the assessment of direct, indirect, and semi- direct effects of aerosols on the Earth radiative balance. Since 1998 the U.S. Department of Energy Atmospheric Radiation Measurement program has continuously operated a fully automated Raman Lidar at its Southern Great Plains site in Oklahoma. Its capability of measuring profiles of aerosol extinction and water vapor has been critically assessed using remote sensing and in situ aircraft measurements from the 2003 Aerosol Intensive Operations Period (AIOP). These comparisons revealed that the Raman Lidar's sensitivity had degraded significantly and the derived extinction profiles had developed a significant positive bias. Major upgrades to the Raman Lidar made in 2004 resulted in dramatically improved sensitivity and reduced random errors. The ARM program also operates Micro Pulse Lidars (MPL) at all of its fixed and mobile sites. When combined with a ground-based measurement of aerosol optical depth (AOD), aerosol extinction profiles can be derived from MPL data. Finally from 2000- 2007 the ARM program has conducted in-situ aerosol profile (IAP) flights using a small aircraft measuring profiles of aerosol scattering and absorption. An aircraft campaign focused on quantifying the improvements of the Raman Lidar and on validating the MPL extinction profiles - the Aerosol Lidar Validation Campaign (ALIVE) - was conducted in 2005. In both the AIOP and ALIVE campaigns the NASA Ames Airborne 14-channel Sunphotometer (AATS-14) was used as the comparison basis for vertically resolved aerosol extinction measurements. Additionally, coordinated flights between the IAP aircraft and the aircraft carrying AATS-14 in AIOP and ALIVE allow an assessment of the IAP's capability to measure aerosol extinction. The AATS-14 instrument has been used for the same purpose in many campaigns outside the ARM program. It is increasingly seen as the solid benchmark against which other measurements of ambient extinction profile measurements are compared. In this paper we show the comparisons derived from the ALIVE data (and not previously published AIOP IAP vs. AATS-14 comparisons) and put these in context with the previously published AIOP comparisons.

Schmid, B.; Turner, D.; Ferrare, R.; Flynn, C.; Newsom, R.; Andrews, E.; Ogren, J.; Johnson, R.; Clayton, M.

2008-12-01

331

Remote measurement of tropospheric parameters by lidar  

NASA Astrophysics Data System (ADS)

Emission and immission measurements and the investigation of transport phenomena of acid gases such as SO2, NO2, and HCl with a differential absorption and scattering lidar are described. A Raman lidar for CO2 and moisture profiling is presented. A Rayleigh temperature lidar is introduced.

Weitkamp, C.

1985-11-01

332

Aerosol Properties Computed from Aircraft-based Observation during the ACE-Asia Campaign: 2. A Case Study of Lidar Radio Closure and Aerosol Radioactive Effects.  

National Technical Information Service (NTIS)

For a vertical profile with three distinct layers (marine boundary, pollution and dust), observed during the ACE-Asia campaign, we carried out a comparison between the modeled lidar ratio vertical profile and that obtained from collocated airborne NASA AA...

E. J. Welton M. Kuzmanoski M. A. Box B. Schmid G. P. Box J. Wang

2005-01-01

333

Use of spaceborne lidar for the evaluation of thin cirrus contamination and screening in the Aqua MODIS Collection 5 aerosol products  

NASA Astrophysics Data System (ADS)

Cloud contamination from subvisual thin cirrus clouds is still a challenging issue for operational satellite aerosol retrievals. In the A-Train constellation, concurrent high-sensitivity cirrus observations from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) provide us with an unprecedented opportunity to examine the susceptibility of the Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) aerosol retrievals to thin cirrus contamination and to evaluate the robustness of various cirrus screening techniques. Quantitative evaluations indicate that the current cirrus screening schemes in the MODIS Dark Target and Deep Blue Collection 5 aerosol retrievals can effectively remove most cirrus signals while some residual thin cirrus signals still exist with strong spatial and seasonal variability. Results also show significant linkage between thin cirrus occurrence frequency and the susceptibility of aerosol retrievals to thin cirrus contamination. Using the CALIPSO cirrus observations as a reference, we also examined the effectiveness and robustness of eight MODIS-derived cirrus screening parameters. These parameters include apparent reflectance at 1.38 µm (R1.38), cirrus reflectance at 0.66 µm (CR0.66), CR0.66 cirrus flag (CF), reflectance ratio between 1.38 µm and 0.66 µm (RR1.38/0.66), reflectance ratio between 1.38 µm and 1.24 µm (RR1.38/1.24), brightness temperature difference between 8.6 µm and 11 µm (BTD8.6-11), brightness temperature difference between 11 µm and 12 µm (BTD11-12), and cloud phase infrared approach (CPIR). Among these parameters, RR1.38/0.66 achieves the best overall performance, followed by the BTD11-12. Results from several test cases suggest that the cirrus screening schemes in the operational MODIS aerosol retrieval algorithms can be further improved to reduce thin cirrus contamination.

Huang, Jingfeng; Hsu, N. Christina; Tsay, Si-Chee; Liu, Zhaoyan; Jeong, Myeong-Jae; Hansell, Richard A.; Lee, Jaehwa

2013-06-01

334

Direct-detection Doppler wind measurements with a Cabannes-Mie lidar: b. Impact of aerosol variation on iodine vapor filter methods.  

PubMed

Atmospheric line-of-sight (LOS) wind measurement by means of incoherent Cabannes- Mie lidar with three frequency analyzers, two double-edge Fabry-Perot interferometers, one at 1064 nm (IR-FPI) and another at 355 nm (UV-FPI), as well as an iodine vapor filter (IVF) at 532 nm, utilizing either a single absorption edge, single edge (se-IVF), or both absorption edges, double edge (de-IVF), was considered in a companion paper [Appl. Opt. 46, 4434 (2007)], assuming known atmospheric temperature and aerosol mixing ratio, Rb. The effects of temperature and aerosol variations on the uncertainty of LOS wind measurements are investigated and it is found that while the effect of temperature variation is small, the variation in R(b) can cause significant errors in wind measurements with IVF systems. Thus the means to incorporate a credible determination of R(b) into the wind measurement are presented as well as an assessment of the impact on wind measurement uncertainty. Unlike with IVF methods, researchers can take advantage of design flexibility with FPI methods to desensitize either molecular scattering for IR-FPI or aerosol scattering for UV-FPI. The additional wind measurement uncertainty caused by R(b) variation with FPI methods is thus negligible for these configurations. Assuming 100,000 photons from Cabannes scattering, and accounting for the Rb measurement incorporated into the IVF method in this paper, it is found that the lowest wind uncertainty at low wind speeds in aerosol-free air is still with UV-FPI, ~32% lower than with de-IVF. For 0.050.07, the IR-FPI outperforms all other methods. In addition to LOS wind uncertainty comparison under high wind speed conditions, the need of an appropriate and readily available narrowband filter for operating the wind lidar at visible wavelengths under sunlit condition is discussed; with such a filter the degradation of LOS wind measurement attributable to clear sky background is estimated to be 5% or less for practical lidar systems. PMID:17579700

She, Chiao-Yao; Yue, Jia; Yan, Zhao-Ai; Hair, Johnathan W; Guo, Jin-Jia; Wu, Song-Hua; Liu, Zhi-Shen

2007-07-10

335

Lidar calibration  

NASA Astrophysics Data System (ADS)

Owing to its inherent low gain detection of the 1064nm channel and a negligible molecular return from the atmosphere, a boundary condition for the retrieval of optical data by inversion cannot be assumed with high confidence as for the other channels in the multiwavelength Mie lidar. It is therefore necessary to evaluate the calibration constant for the 1064nm channel. Two methods of calibration are studied and compared. One method is calibration by high or low clouds. The other method is calibration by a ceilometer which is itself calibrated and co-located at the lidar site. The results are compared with the aerosol optical depth measured by a calibrated sun photometer co-located at the same site as part of the AERONET network at CCNY. In the latter method, all three instruments are located at the same site, there is no issue of atmospheric differences when comparing data but it makes calibration dependent on that of other instruments. Clouds are a natural and frequent occurrence but the lidar system may change between cloud appearances. Both methods have their merits and shortcomings.

Chaw, Shuki

336

Validation of the version 5 Goddard Earth Observing System (GEOS-5) using Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO)  

NASA Astrophysics Data System (ADS)

This dissertation compares the Planetary Boundary Layer (PBL) height produced by the Goddard Earth Observing System-version 5 (GEOS-5) model with Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO). Part of GEOS-5 is an Atmosphere Global Circulation Model (GCM). Developers are uncertain of the precision of model PBL height predictions (i.e. climatology), since there are limited direct observations of the PBL height. Validation of the PBL height serves as a diagnostic on whether the physics and dynamics packages are correct in the model. Thus, verification is needed. For the first time ever, PBL heights have been derived from CALIPSO using a new hybrid standard deviation algorithm, which in some cases is more sensitive than traditional approaches (i.e. Haar wavelet method). Observations made at the UMBC Elastic Lidar Facility (ELF) have been used to determine the validity of the satellite-derived PBL estimate. This is the first global observational study of PBL heights using CALIPSO with match-ups to the GEOS-5 MERRA model. Extensive comparisons between the model output and satellite observations in the western Hemisphere and over Africa gave model-measurement correlation coefficients between 0.47--0.73. Comparisons have been performed for regions over land and water using clouds, aerosols and mixed cloud-aerosol features to detect the PBL. The present study provides insight of PBL height variances in the GEOS-5 model. A case over the Equatorial Pacific indicates that PBL heights from the GEOS-5 model are greater than 25%, on average, than the satellite-derived PBL parameter. PBL height biases in the Equatorial Pacific may be related to the General Circulation Model (GCM) coupling scheme implemented in GEOS-5.

Jordan, Nikisa Samantha

337

A wavelet-based spectral analysis of long-term time series of optical properties of aerosols obtained by lidar and radiometer measurements over an urban station in Western India  

NASA Astrophysics Data System (ADS)

Over 700 weekly-spaced vertical profiles of aerosol number density have been archived during 14-year period (October 1986-September 2000) using a bi-static Argon ion lidar system at the Indian Institute of Tropical Meteorology, Pune (18°43?N, 73°51?E, 559 m above mean sea level), India. The monthly resolved time series of aerosol distributions within the atmospheric boundary layer as well as at different altitudes aloft have been subjected to the wavelet-based spectral analysis to investigate different characteristic periodicities present in the long-term dataset. The solar radiometric aerosol optical depth (AOD) measurements over the same place during 1998-2003 have also been analyzed with the wavelet technique. Wavelet spectra of both the time series exhibited significant quasi-annual (around 12-14 months) and quasi-biennial (around 22-25 months) oscillations at statistically significant level. An overview on the lidar and radiometric data sets including the wavelet-based spectral analysis procedure is also presented. A brief statistical analysis concerning both annual and interannual variability of lidar and radiometer derived aerosol distributions has been performed to delineate the effect of different dominant seasons and associated meteorological conditions prevailing over the experimental site in Western India. Additionally, the impact of urbanization on the long-term trends in the lidar measurements of aerosol loadings over the experimental site is brought out. This was achieved by using the lidar observations and a preliminary data set built for inferring the urban aspects of the city of Pune, which included population, number of industries and vehicles etc. in the city.

Pal, S.; Devara, P. C. S.

2012-08-01

338

Progress report of FY 1998 activities: The application of Kalman filtering to derive water vapor profiles from combined ground-based sensors: Raman lidar, microwave radiometers, GPS, and radiosondes  

SciTech Connect

Previously, the proposers have delivered to ARM a documented algorithm, that is now applied operationally, and which derives water vapor profiles from combined remote sensor measurements of water vapor radiometers, cloud-base ceilometers, and radio acoustic sounding systems (RASS). With the expanded deployment of a Raman lidar at the CART Central Facility, high quality, high vertical-resolution, water vapor profiles will be provided during nighttime clear conditions, and during clear daytime conditions, to somewhat lower altitudes. The object of this effort is to use Kalman Filtering, previously applied to the combination of nighttime Raman lidar and microwave radiometer data, to derive high-quality water vapor profiles, during non-precipitating conditions, from data routinely available at the CART site. Input data to the algorithm would include: Raman lidar data, highly quality-controlled data of integrated moisture from microwave radiometers and GPS, RASS, and radiosondes. The focus of this years activities has been on the intercomparison of data obtained during the Water Vapor Intensive Operating Period'97 at the SGP CART site in central Oklahoma.

Edgeworth R. Westwater; Yong Han

1999-10-01

339

Progress report of FY 1997 activities: The application of Kalman filtering to derive water vapor profiles from combined ground-based sensors: Raman lidar, microwave radiometers, GPS, and radiosondes  

SciTech Connect

Previously, the proposers have delivered to ARM a documented algorithm, that is now applied operationally, and which derives water vapor profiles from combined remote sensor measurements of water vapor radiometers, cloud-base ceilometers, and radio acoustic sounding systems (RASS). With the expanded deployment of a Raman lidar at the CART Central Facility, high quality, high vertical-resolution, water vapor profiles will be provided during nighttime clear conditions, and during clear daytime conditions, to somewhat lower altitudes. The object of this proposal was to use Kalman Filtering, previously applied to the combination of nighttime Raman lidar and microwave radiometer data, to derive high-quality water vapor profiles, during non-precipitating conditions, from data routinely available at the CART site. Input data to the algorithm would include: Raman lidar data, highly quality-controlled data of integrated moisture from microwave radiometers and GPS, RASS, and radiosondes. The algorithm will include recently-developed quality control procedures for radiometers. The focus of this years activities has been on the intercomparison of data obtained during an intensive operating period at the SGP CART site in central Oklahoma.

Edgeworth R. Westwater; Yong Han

1997-10-05

340

Progress report of FY 1999 activities: The application of Kalman filtering to derive water vapor profiles from combined ground-based sensors: Raman lidar, microwave radiometers, GPS, and radiosondes  

SciTech Connect

Previously, the proposers have delivered to ARM a documented algorithm, that is now applied operationally, and which derives water vapor profiles from combined remote sensor measurements of water vapor radiometers, cloud-base ceilometers, and radio acoustic sounding systems (RASS). With the expanded deployment of a Raman lidar at the CART Central Facility, high quality, high vertical-resolution, water vapor profiles will be provided during nighttime clear conditions, and during clear daytime conditions, to somewhat lower altitudes. The object of this effort is to use Kalman Filtering, previously applied to the combination of nighttime Raman lidar and microwave radiometer data, to derive high-quality water vapor profiles, during non-precipitating conditions, from data routinely available at the CART site. Input data to the algorithm would include: Raman lidar data, highly quality-controlled data of integrated moisture from microwave radiometers and GPS, RASS, and radiosondes. While analyzing data obtained during the Water Vapor Intensive Operating Period'97 at the SGP CART site in central Oklahoma, several questions arose about the calibration of the ARM microwave radiometers (MWR). A large portion of this years effort was a thorough analysis of the many factors that are important for the calibration of this instrument through the tip calibration method and the development of algorithms to correct this procedure. An open literature publication describing this analysis has been accepted.

Edgeworth R. Westwater; Yong Han

1999-09-10

341

Observation of non-spherical ultragiant aerosol using a microwave radar  

NASA Astrophysics Data System (ADS)

Observations of ultragiant aerosol particles performed at the CNR-IMAA Atmospheric Observatory using a Ka-Band Doppler radar in four different periods from 19 April to 13 May 2010 are presented. In the reported cases, the aerosol radar signatures are characterized by a similar scenario. In particular, the linear depolarization ratio shows values higher than -4 dB probably related to the effect of bulk density and to the non-sphericity of the ultragiant particles. During the same period, volcanic aerosol layers coming from Eyjafjallajökull volcano were observed over most of European countries, including Southern Italy, using lidar technique. The observation of volcanic layers over Potenza by multi-wavelength Raman lidar measurements suggests a volcanic origin of the ultragiant aerosol particles observed by the radar, revealing that these particles might travel in the atmosphere for more than 4000 km after their injection in the atmosphere.

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

2010-11-01

342

Mapping aerosol intrusion in Himalayan valleys using the Moderate Resolution Imaging Spectroradiometer (MODIS) and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO)  

NASA Astrophysics Data System (ADS)

Mapping the spatial and temporal distribution of aerosols along mountain ranges is an important step toward elucidating orographic aerosol-cloud-rainfall interactions. This requires high spatial resolution aerosol observations over complex topography, which are not currently available either from ground-based observing systems or from remote-sensing products. Here, a novel approach is presented that relies on visible channels from MODIS Rapid Response data at 250 m spatial resolution to extract the daytime aerosol run-up (intrusion length and height) from the Indo-Gangetic Plains to the High Himalaya. Intrusion length and height are determined from the intersection of topography with the MODIS-derived aerosol plume using an adaptive object-classification algorithm. The methodology is demonstrated for a case study of the Arun River in eastern Nepal. Results of run-up extraction are examined along with the Total Attenuated Backscatter (Level 1B at 532 nm) from CALIPSO to investigate the regional variability of aerosol. During the pre-monsoon season, CALIPSO nighttime profiles show the presence of a slanted dust layer following the envelope topography. This is consistent with upper level transport of aerosol by north-westerly winds associated with high-frequency dust storms. In the winter, the signal is weaker, and the nighttime elevated aerosol layer is flat and remains below the envelope orography consistent with blocking conditions. For both seasons, the daytime aerosol layer detected from MODIS observations is always below the ridges. This suggests that in addition to seasonal variability governed by synoptic conditions, there is a distinct diurnal cycle in the North-South transport of aerosol between the Himalayas and the IGP.

Brun, Julien; Shrestha, Prabhakar; Barros, Ana P.

2011-11-01

343

An Assessment of Cloud and Aerosol Radiative Forcing from CERES with Independent Passive (Ground Networks) and Active (Calipso Lidar) Measurements  

Microsoft Academic Search

Much of the interest in clouds and aerosols relates to the direct radiative forcing of these atmospheric constituents. Satellite data are the main tools for estimating both cloud and aerosol forcing on the global scale. What are the strengths and weaknesses of the satellite record for these forcings? Here we test the CERES Terra (March 2000 - December 2006) and

T. P. Charlock; F. G. Rose; D. A. Rutan; Z. Jin

2008-01-01

344

A lidar instrument to measure H2O and aerosol profiles from the NASA ER-2 aircraft  

NASA Astrophysics Data System (ADS)

Plans to develop the Lidar Atmospheric Sensing Experiment (LASE) instrument to conduct scientific experiments aboard a NASA U-2 (ER-2) aircraft are described. The LASE measurement objectives are listed, and the design of the LASE instrument is discussed, including performance criteria for the laser transmitter, wavemeter, telescope, optical receiver, and associated electronics. The instrument function is depicted with a block diagram, and layouts of various components are presented.

Vaughan, W. R.; Browell, E. V.; Hall, W. M.; Averill, R. D.; Wells, J. G.; Hinton, D. E.; Goad, J. H.; Degnan, J. J.

1986-01-01

345

Raman scattering in the Jupiter's atmosphere and optical properties of atmospheric aerosol  

Microsoft Academic Search

The basis of nonlinear atmospheric optic is considered here. When Sun radiation cross the Jupiter's atmosphere, such nonlinear optical effect as Raman scattering will be appear. For our investigations, we used the spectral observations received by E.Karkoshka in 1993 and 1995 on the ESO (European Southern Observatory) from 300 to 1000 nm. We received such nonlinear optical effects as Raman

N. Kostogryz; A. Morozhenko; A. Vidmachenko

2004-01-01

346

Ground-based lidar measurements from Ny-Ålesund during ASTAR 2007: a statistical overview  

NASA Astrophysics Data System (ADS)

During the Arctic Study of Tropospheric Aerosol, Clouds and Radiation (ASTAR) in March and April 2007, measurements obtained at the AWIPEV Research station in Ny-Ålesund, Spitsbergen (operated by the Alfred-Wegener-Institute for Polar and Marine Research and the Institut polaire français Paul-Emile Victor), supported the airborne campaign. This included Lidar data from the Koldewey Aerosol Raman Lidar (KARL) and the Micro Pulse Lidar (MPL), located in the atmospheric observatory as well as photometer data and the daily launched radiosonde. The MPL features nearly continuous measurements; the KARL was switched on whenever weather conditions allowed observations (145 h in 61 days). From 1 March to 30 April, 71 meteorological balloon soundings were performed and compared with the corresponding MPL measurements; photometer measurements are available from 18 March. For the KARL data, a statistical overview based on the optical properties backscatter ratio and volume depolarization can be given. The altitudes of the occurrence of the named features (subvisible and visible ice and water as well as mixed-phase clouds, aerosol layers) as well as their dependence on different air mass origins are analyzed. Although the spring 2007 was characterized by rather clean conditions, diverse case studies of cloud and aerosol occurrence during March and April 2007 are presented in more detail, including temporal development and main optical properties as backscatter, depolarization and extinction coefficients. Links between air mass origins and optical properties can be presumed but need further evidence.

Hoffmann, A.; Ritter, C.; Stock, M.; Shiobara, M.; Lampert, A.; Maturilli, M.; Orgis, T.; Neuber, R.; Herber, A.

2009-07-01

347

A novel approach for the characterization of transport and optical properties of aerosol particles near sources - Part I: Measurement of particle backscatter coefficient maps with a scanning UV lidar  

NASA Astrophysics Data System (ADS)

The physical and chemical properties of aerosols emitted from a livestock farm were determined by a novel approach which combines high-resolution lidar measurements (0.33 s, 30 m) with simulations of a microphysics-chemistry-transport model. This first of two companion papers describes the scanning lidar measurements of optical particle properties. The lidar system employed laser radiation at a wavelength of 355 nm with a power of 9 W and a pulse repetition rate of 30 Hz. The laser beam was expanded before transmission to the atmosphere so that it became eye-safe at distances >270 m to the lidar. The elastic backscatter signal was detected with a resolution of 0.033 s and 3 m. A receiving telescope with a primary-mirror diameter of 40 cm was used. For this system, we developed a novel method for two-dimensional retrievals of the particle backscatter coefficient. With this set up and approach, the lidar was able to identify the aerosol plume up to a range of ˜2.5 km from the source, a farm in northern Germany, in daytime. The measurements confirm that the optical particle properties of the emission plume vary largely with distance from the source and that the maximum particle backscatter coefficient is found away from the source. Within a close-to-horizontal scan (elevation angle of 2.3°), we found a mean particle backscatter coefficient of 1.5·10 -5 m -1 sr -1 inside the plume between 1.5 and 2.0 km distance from the source. Subtraction of the mean particle backscatter coefficient of the background aerosol present in this case (4.1·10 -6 m -1 sr -1) yields a particle backscatter coefficient of the livestock aerosols of 1.1·10 -5 m -1 sr -1. The limited extend of the plume is revealed with the scanning lidar: Scans with a slightly higher elevation angle of 4.8° did not pick up the plume.

Behrendt, Andreas; Pal, Sandip; Wulfmeyer, Volker; Valdebenito B., Álvaro M.; Lammel, Gerhard

2011-05-01

348

LIDAR system of CLF  

NASA Astrophysics Data System (ADS)

UV fluorescence light generated by an air shower is scattered and lost along the path of propagation to the telescope. The cause of the main scattering is due to the atmospheric molecule and the aerosol. The calibration of a decrease in the photocount by scattering the atmosphere is very important as well as the calibration of the Fluorescence Detectors (FD). Two atmospheric scattered monitoring devices (LIDAR and CLF) have already been operating in the Telescope Array (TA) experiment. New LIDAR system is constructed at CLF and concentrated the advantage of two current atmospheric transparency monitoring devices. It reports on the upgrade of an existing atmospheric scattered monitoring device in TA in this paper.

Oku, D.; Tomida, T.

2011-09-01

349

African Dust Transport Across the North Atlantic: The Temporal Variability of Aerosol Vertical Distributions Based on Micropulse Lidar Measurements on Barbados (Invited)  

NASA Astrophysics Data System (ADS)

The study of African dust transport across the Atlantic began in 1965 in ground-based studies carried out on Barbados. In 1969 aircraft studies in BOMEX suggested that on average the highest dust concentrations were aloft, above the marine boundary layer (MBL), typically extending to 700mb [Prospero and Carlson, 1972; Carlson and Prospero, 1972]. This dust-laden layer was characterized by a relatively high and constant potential temperature and a low mixing ratio, properties that were linked to the origins of the air parcels over the deserts of North Africa. On the basis of these features, the layer was named the Saharan Air Layer (SAL). Except for a one month study in Puerto Rico in 2000 (PRIDE), there has been no systematic effort to better characterize the vertical distribution of dust, the associated synoptic settings of these events, and the seasonal variability. Consequently, 40 years after the "discovery" of the SAL, this crude picture of dust transport remains essentially unchanged. To address this issue, in 2008, in conjunction with the NASA MPLNET program, a micropulse lidar (MPL) was installed at the University of Miami aerosol research station on the east coast of Barbados. Two years of MPL operations provide us with a unique picture of the variability of aerosol vertical structure after a week's transit from sources over 5000km distant. A remarkable feature in these data is the frequent presence of aerosol layers, in most cases clearly dominated by dust. These layers often remain stable and sharply defined over the course of a day to as many as several days as they pass over the site. Also located at this site is a NASA AERONET aerosol photometer. These collocated instruments enable the retrieval of vertical profiles of extinction and optical depth. During dust events, the major part of the extinction takes place above the MBL. Here we present an overview of the MPL studies over this two year period. We focus mainly on major dust events that typically occur during the summer dust season. As a test of the SAL scenario, we examine these distributions in relation to meteorological soundings made on Barbados in an effort to link the dust layers to meteorological features in the soundings. We will also use other satellite products (e.g., SeaWiFS, MODIS, CALIPSO) to place our MPL data in a larger-scale context.

Prospero, J. M.; Welton, E. J.

2010-12-01

350

Error analysis for elastic-backscattering lidar  

NASA Astrophysics Data System (ADS)

Elastic backscattering LIDAR represents one of the most promising tools for attaining remotely information about the distribution of aerosols and particulates in the atmosphere, which could lead to a better understanding of climate processes. In this paper we shall examine the uncertainties associated with such measurements and try to determine which of the LIDAR parameters need to be optimized in order to minimize the measurement errors. An optimization method of the operative characteristic associated with the LIDAR signal validation is also proposed.

Talianu, Camelia; Nicolae, Doina N.; Ciobanu, Mircea; Babin, Vasile D.; Cristescu, Constantin P.

2004-10-01

351

Performance analysis for standoff biological warfare agent detection lidar  

Microsoft Academic Search

Lidar has been identified as a promising sensor for remote detection of biological warfare agents. Elastic lidar can be used for cloud detection at long ranges and UV laser induced fluorescence can be used for discrimination of bioaerosols against naturally occurring aerosols. This paper analyzes the performance of elastic lidar such as sensitivity, range and angular coverage rate vs. atmospheric

Ove Steinvall; Per Jonsson; Fredrik Kullander

2007-01-01

352

Raman lidar measurements of water vapor and aerosol/clouds during the FIRE/SPECTRE field campaign.  

National Technical Information Service (NTIS)

The FIRE/SPECTRE field campaign was conducted during November- December 1991 in Coffeyville, Kansas. The main objective of FIRE (First ISCCP (International Satellite Cloud Climatology Project) Regional Experiment) was to study the development and radiativ...

S. H. Melfi D. Whiteman R. Ferrare K. Evans J. E. M. Goldsmith

1992-01-01

353

Minority Species Detection in Aerosols by Stimulated Anti-Stokes Raman Scattering and External Seeding  

NASA Astrophysics Data System (ADS)

A novel technique applicable to remote sensing has been developed for determination of the chemical composition of microdroplets. Enhancement of stimulated anti-Stokes Raman scattering (SARS) by external seeding of stimulated Raman scattering (SRS) at the Stokes shift lowers the detection limit of the minority species in multicomponent microdroplets. The technique is most useful in the investigation of microdroplets that contain fluorophores that can obscure the SRS signal. The SARS signal is to the blue of the pump laser and out of the fluorescence region of the fluorophore. Information about majority and minority species in multicomponent microdroplets can be determined from the enhanced SARS signals.

Roman, Victor E.; Popp, Jürgen; Fields, Mitchell H.; Kiefer, Wolfgang

1999-03-01

354

a High Spectral Resolution LIDAR Using AN Iodine Vapor Filter at 589 NM  

NASA Astrophysics Data System (ADS)

A high-spectral resolution Rayleigh-Mie lidar based on an iodine vapor filter and operating at 589 nm has been developed. The use of an iodine vapor filter as a band stop filter has allowed the separation of Rayleigh and Mie scattering signals. This allows the lidar to measure atmospheric state variables and optical aerosol properties as a stand alone device. This lidar uses a narrow band pulsed laser as a light source, Rayleigh scattering by the atmosphere to provide a return signal, Doppler free saturated absorption spectra to provide an absolute frequency scale, and the absorption spectrum of iodine as a band stop filter. The determination of atmospheric and aerosol parameters relies on knowing the characteristics of the iodine absorption cell obtained by laboratory experiments. The analysis uses the theoretical Rayleigh-Brillouin frequency scattering function, as well as the assumption that the atmosphere is in hydrostatic equilibrium and acts as an ideal gas. It is also necessary to input or pin the air pressure at one altitude. This lidar implements features not present in the previous version. Locking to a frequency reference and monitoring the quality of the locking, installation of a 1 A norrowband interference filter, and most importantly using a temperature stabilized iodine vapor cell as the ultra-narrow band stop filter. These improvements result, respectively, in elimination of rotational Raman scattering from the lidar return, in a more stable laser frequency, and a more precise vapor filter transmission function. These, together, have resulted in improved lidar performance. Uncertainties in the experiment are predominately due to photon noise which may be reduced by various methods of increasing photon counts. Results of the field experiment are presented in profiles averaged over 82 minutes, semi-nightly, and nightly averages. For an integration time of 82 minutes the temperature can be measured at 1 km to within 4.6K, the volume backscatter ratio to 1% and the depolarization ratio to 2.4%.

Caldwell, Loren Max, Jr.

355

Lidar Report  

SciTech Connect

This report provides an overview of the LiDAR acquisition methodology employed by Woolpert on the 2009 USDA - Savannah River LiDAR Site Project. LiDAR system parameters and flight and equipment information is also included. The LiDAR data acquisition was executed in ten sessions from February 21 through final reflights on March 2, 2009; using two Leica ALS50-II 150kHz Multi-pulse enabled LiDAR Systems. Specific details about the ALS50-II systems are included in Section 4 of this report.

Wollpert.

2009-04-01

356

Boundary Layer Observations of Water Vapor and Aerosol Profiles with an Eye-Safe Micro-Pulse Differential Absorption Lidar (DIAL)  

NASA Astrophysics Data System (ADS)

Measurements of real-time high spatial and temporal resolution profiles of combined water vapor and aerosols in the boundary layer have been a long standing observational challenge to the meteorological, weather forecasting, and climate science communities. To overcome the high reoccurring costs associated with radiosondes as well as the lack of sufficient water vapor measurements over the continental united states, a compact and low cost eye-safe all semiconductor-based micro-pulse differential absorption lidar (DIAL) has been developed for water vapor and aerosol profiling in the lower troposphere. The laser transmitter utilizes two continuous wave external cavity diode lasers operating in the 830 nm absorption band as the online and offline seed laser sources. An optical switch is used to sequentially injection seed a tapered semiconductor optical amplifier (TSOA) with the two seed laser sources in a master oscillator power amplifier (MOPA) configuration. The TSOA is actively current pulsed to produce up to 7 ?J of output energy over a 1 ?s pulse duration (150 m vertical resolution) at a 10 kHz pulse repetition frequency. The measured laser transmitter spectral linewidth is less than 500 kHz while the long term frequency stability of the stabilized on-line wavelength is ± 55 MHz. The laser transmitter spectral purity was measured to be greater than 0.9996, allowing for simultaneous measurements of water vapor in the lower and upper troposphere. The DIAL receiver utilizes a commercially available full sky-scanning capable 35 cm Schmidt-Cassegrain telescope to collect the scattered light from the laser transmitter. Light collected by the telescope is spectrally filtered to suppress background noise and is coupled into a fiber optic cable which acts as the system field stop and limits the full angle field of view to 140 ?rad. The light is sampled by a fiber coupled APD operated in a Geiger mode. The DIAL instrument is operated autonomously where water vapor and aerosol profiles are displayed in real-time. The transmitter is capable of operating at any spectral position along the selected water vapor absorption line allowing for year round operation at various geographical locations using a single line. Water vapor and aerosol profiles have been recorded up to 6 km and 15 km with 10 m and 1 m temporal averaging, respectively, allowing for mesoscale monitoring of boundary layer dynamics during both daytime and nighttime operation. A brief description of the current status of the water vapor DIAL instrument will be presented. Nighttime and daytime water vapor and aerosol profiles/inversions from the DIAL instrument will also be presented and favorable comparisons against collocated radiosonde, in situ, and column averaged data from SUOMINET and AERONET will also be discussed. A future outlook towards instrument enhancements that will allow the diode-laser-based DIAL technique/technology to become a viable candidate for deployment in multi-point sensor networks will also be discussed.

Nehrir, A. R.; Repasky, K. S.; Carlsten, J.; Ismail, S.

2011-12-01

357

Aerosols  

PubMed Central

We and others have recently reported that prions can be transmitted to mice via aerosols. These reports spurred a lively public discussion on the possible public-health threats represented by prion-containing aerosols. Here we offer our view on the context in which these findings should be placed. On the one hand, the fact that nebulized prions can transmit disease cannot be taken to signify that prions are airborne under natural circumstances. On the other hand, it appears important to underscore the fact that aerosols can originate very easily in a broad variety of experimental and natural environmental conditions. Aerosols are a virtually unavoidable consequence of the handling of fluids; complete prevention of the generation of aerosols is very difficult. While prions have never been found to be transmissible via aerosols under natural conditions, it appears prudent to strive to minimize exposure to potentially prion-infected aerosols whenever the latter may arise—for example in scientific and diagnostic laboratories handling brain matter, cerebrospinal fluids, and other potentially contaminated materials, as well as abattoirs. Equally important is that prion biosafety training be focused on the control of, and protection from, prion-infected aerosols.

2011-01-01

358

Interpretative synergy of starphotometry and lidar measurements at two high-Arctic stations during the Polar Winter of 2010-11  

NASA Astrophysics Data System (ADS)

Aerosols can significantly alter the Arctic's delicate radiative balance, both directly by absorbing and scattering solar and terrestrial radiation, and indirectly by influencing cloud properties through their critical role as cloud condensation nuclei. The understanding of aerosol dynamics, however, is especially poor in the Arctic, where our knowledge of the actual aerosol load, transport as well as physical and chemical properties is very limited. Among the biggest limitations is the absence of consistent night-time aerosol optical depth (AOD) measurements during the Polar Winter. AOD is a multi-spectral indicator of the total vertical extinction due to atmospheric aerosols and is one of the most important (aerosol) radiative forcing parameters. During the day, AOD is traditionally measured using the well-known sunphotometry technique, but night-time AOD measurements up to now have been extremely scarce. Recently developed starphotometry techniques based on extinction measurements of bright-star radiation help to mitigate the lack of any type consistent and regular Polar Night measurements. In an effort to address the dearth of AOD measurements during the Polar Winter , two starphotometers (denoted as SP-NYA and SP-PRL) were installed at two key high-Arctic stations: AWIPEV base at Ny Alesund (Spitsbergen, 78°55"N, 11°55"E) and the PEARL observatory at Eureka, Canada (79°59'N, 85°56'W). In the fall of 2010 both instruments were upgraded, in part to allow semi-automatic data acquisition with remote control capabilities. In addition to starphotometers, both stations are equipped with aerosol backscatter lidar systems: KARL (Koldeway Raman Lidar) and MPL (Micropulsed Lidar) at Ny Alesund and CRL (CANDAC Raman Lidar) at Eureka. During the 2010-11Polar Winter (Oct 2010-Mar 2011) measurements were performed whenever possible. We present preliminary event-driven results, for key optical parameters such as multi-band AOD, fine-mode (sub-micron) and coarse-mode (super-micron) optical depths that are derived from the star extinction measurements. We also show how the starphotometry-lidar synergy can be used in a routine analysis to better detect and characterize aerosol events. Finally, based on the preliminary evidence from satellite data and backward trajectories, we give some examples of potential aerosol transport into the Arctic during the Polar Winter.

Baibakov, K.; O'Neill, N. T.; Herber, A.; Ritter, C.; Duck, T. J.; Schulz, K.; Schrems, O.

2011-12-01

359

Aerosol Properties Computed from Aircraft-Based Observations During the ACE-Asia Campaign: 2. A Case Study of Lidar Ratio Closure  

Microsoft Academic Search

For a vertical profile with three distinct layers (marine boundary, pollution, and dust layers), observed during the ACE-Asia campaign, we carried out a comparison between the modeled lidar ratio vertical profile and that obtained from co-located airborne NASA AATS-14 sunphotometer and shipborne Micro-Pulse Lidar (MPL) measurements. The vertically resolved lidar ratio was calculated from two size distribution vertical profiles—one obtained

M. Kuzmanoski; M. A. Box; B. Schmid; G. P. Box; J. Wang; P. B. Russell; D. Bates; H. H. Jonsson; E. J. Welton; J. H. Seinfeld

2007-01-01

360

Lidar backscatter signal recovery from phototransistor systematic effect by deconvolution.  

PubMed

Backscatter lidar detection systems have been designed and integrated at NASA Langley Research Center using IR heterojunction phototransistors. The design focused on maximizing the system signal-to-noise ratio rather than noise minimization. The detection systems have been validated using the Raman-shifted eye-safe aerosol lidar (REAL) at the National Center for Atmospheric Research. Incorporating such devices introduces some systematic effects in the form of blurring to the backscattered signals. Characterization of the detection system transfer function aided in recovering such effects by deconvolution. The transfer function was obtained by measuring and fitting the system impulse response using single-pole approximation. An iterative deconvolution algorithm was implemented in order to recover the system resolution, while maintaining high signal-to-noise ratio. Results indicated a full recovery of the lidar signal, with resolution matching avalanche photodiodes. Application of such a technique to atmospheric boundary and cloud layers data restores the range resolution, up to 60 m, and overcomes the blurring effects. PMID:18846166

Refaat, Tamer F; Ismail, Syed; Abedin, M Nurul; Spuler, Scott M; Mayor, Shane D; Singh, Upendra N

2008-10-10

361

Average Aerosol Extinction and Water Vapor Profiles Over the Southern Great Plains  

SciTech Connect

An operational Raman lidar deployed at the DOE Atmospheric Radiation Measurement site in Oklahoma has collected more than 7500 h of aerosol and water vapor data between April 1998 and January 2000. These data, which span a wide variety of atmospheric conditions, have been analyzed as a function of season, integrated amount, and time of day. The scale height of the mean aerosol profiles varies considerably as both a function of season and aerosol optical thickness, with the mean scale height increasing from less than 1 km in the winter to over 2 km during turbid summer days. The mean scale height of the water vapor remained very close to 2 km, regardless of season or precipitable water vapor. Furthermore, the distribution of aerosol optical thickness shows a slight shift to smaller values at night compared to day, and the mean aerosol profiles show little diurnal dependence except at the top of the boundary layer.

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

2001-12-01

362

LIDAR Measurements of Lofted Stratospheric Layers from Biomass Burning  

NASA Astrophysics Data System (ADS)

There has been considerable interest recently resulting from the observation of aerosols in the upper troposphere and stratosphere caused by convection driven by intense forest fire burning - pyrocumulonimbus (pyroCB) events. The Purple Crow Lidar (PCL; 42.87° N, 81.38° W, 225 m elevation) is a Rayleigh-Raman system designed primarily for temperature measurements from the upper troposphere to the lower thermosphere but is also capable of observing aerosol scattering such as that resulting from pyroCB events. Measurements obtained from 450 nominally "clear" nights between 2000-2007 were analyzed for the occurrence of layering events based on morphological criteria which consisted of having: (1) high altitude (above 7.5 km with particular focus on those events above 12.5 km), (2) diffuse appearance lacking significant vertical or temporal structure and (3) persistence of at least several hours. Of these nights, 200 were found to have aerosols (clouds or layers) above 7.5 km altitude, of which 9 were strong candidate matches to the morphological criteria. Aerosols above 12.5 km were also found on 63 nights, of which 5 were strong candidates. A single week in late June and early July 2002 saw 4 of the 5 observed high-altitude, strong candidates. These are quite likely connected with documented pyroCB events from intense fires in Manitoba and Saskatchewan at that time. Measurements from one example night (June 30 2002, top altitude 14.5 km) shows that these layers are associated with strong scattering (up to 10 times the molecular background) and relatively opaque (total optical depth at 532 nm of 0.9 over ˜1 km). A low-level calibration technique will also be applied to provide accurate temperature and relative humidity measurements in the vicinity of these layers to examine the differences between these events and what appear to be high cirrus clouds also measured by the lidar.

Doucet, Paul; Sica, Robert; Argall, Stephen