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1

LOSA-M2 aerosol Raman lidar  

SciTech Connect

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

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

2011-10-31

2

Comparison of Aerosol Extinction From two Raman Lidars  

NASA Astrophysics Data System (ADS)

In this work the retrievals of aerosol extinction from NASA/GSFC SRL (Scanning Raman Lidar) and the DOE (Department Of Energy) CRF (Climate Research Facility) Raman Lidar (CARL) will be compared. CARL is the first completely automated Raman lidar and is situated at the CRF site at SGP (Southern Great Plains). It is recently been used in experiments the main objective of which were to study the remote measurement of aerosol swelling (Ghan et al. 2006) and the possibility of parameterization of the aerosol indirect effect (Feingold et al. 2006). These experiments are of great value in the study of the aerosol indirect effect, which is at the present poorly understood. CARL is able to retrieve aerosol extinction directly from the signal created by Raman scattering from nitrogen molecules at heights above 800m, where the telescope field of view and the laser beam are completely overlapped. To extend the extinction profile to lower altitudes a technique that combines the aerosol extinction and the aerosol backscattering coefficient is used (Turner et al. 2002). From the ratio of the two the extinction to backscattering ratio (lidar ratio) is calculated above 800m. The values obtained are smoothed over 1 hour period and 500m in the vertical, filtered from values outside the range 5-130 sr and then interpolated to fill in the gaps due to the filtering and then extrapolated to the ground. The so-calculated lidar ratio is used to retrieve the aerosol extinction coefficient above 800m. In order to quantify the error introduced by interpolating the lidar ratio to regions where it cannot be measured and its influence on the entire retrieval of the extinction, CARL aerosol extinction profiles are compared to NASA/GSFC SRL. Through the use of a large aperture scan mirror, the SRL has the ability to measure at any angle from the vertical, allowing direct measurements of the aerosol extinction at very low altitudes. The SRL was stationed at the SGP site for separate field campaigns that were held in 1996, 1997 and 2000 resulting in approximately 200 hours of simultaneous CARL/SRL aerosol extinction measurements. The analysis of those measurements will be presented at the conference.

Russo, F.; Whiteman, D. N.; Demoz, B. B.; Hoff, R. M.

2006-05-01

3

Retrieval of aerosol backscatter, extinction, and lidar ratio from Raman lidar with optimal estimation  

NASA Astrophysics Data System (ADS)

Optimal estimation retrieval is a form of nonlinear regression which determines the most probable circumstances that produced a given observation, weighted against any prior knowledge of the system. This paper applies the technique to the estimation of aerosol backscatter and extinction (or lidar ratio) from two-channel Raman lidar observations. It produces results from simulated and real data consistent with existing Raman lidar analyses and additionally returns a more rigorous estimate of its uncertainties while automatically selecting an appropriate resolution without the imposition of artificial constraints. Backscatter is retrieved at the instrument's native resolution with an uncertainty between 2 and 20%. Extinction is less well constrained, retrieved at a resolution of 0.1-1 km depending on the quality of the data. The uncertainty in extinction is > 15%, in part due to the consideration of short 1 min integrations, but is comparable to fair estimates of the error when using the standard Raman lidar technique. The retrieval is then applied to several hours of observation on 19 April 2010 of ash from the Eyjafjallajökull eruption. A depolarising ash layer is found with a lidar ratio of 20-30 sr, much lower values than observed by previous studies. This potentially indicates a growth of the particles after 12-24 h within the planetary boundary layer. A lower concentration of ash within a residual layer exhibited a backscatter of 10 Mm-1 sr-1 and lidar ratio of 40 sr.

Povey, A. C.; Grainger, R. G.; Peters, D. M.; Agnew, J. L.

2014-03-01

4

Measurement of tropospheric aerosol in São Paulo area using a new upgraded Raman LIDAR system  

NASA Astrophysics Data System (ADS)

Elastic backscatter LIDAR systems have been used to determine aerosol profile concentration in several areas such as weather, pollution and air quality monitoring. In order to determine the aerosol extinction and backscattering profiles, the Klett inversion method is largely used, but this method suffers from lack of information since there are two unknown variables to be determined using only one measured LIDAR signal, and assumption of the LIDAR ratio (the relation between the extinction and backscattering coefficients) is needed. When a Raman LIDAR system is used, the inelastic backscattering signal is affected by aerosol extinction but not by aerosol backscatter, which allows this LIDAR to uniquely determine extinction and backscattering coefficients without any assumptions or any collocated instruments. The MSP-LIDAR system, set-up in a highly dense suburban area in the city of São Paulo, has been upgraded to a Raman LIDAR, and in its actual 6-channel configuration allows it to monitor elastic backscatter at 355 and 532 nm together with nitrogen and water vapor Raman backscatters at 387nm and 608 nm and 408nm and 660 nm, respectively. Thus, the measurements of aerosol backscattering, extinction coefficients and water vapor mixing ratio in the Planetary Boundary Layer (PBL) are becoming available. The system will provide the important meteorological parameters such as Aerosol Optical Depth (AOD) and will be used for the study of aerosol variations in lower troposphere over the city of São Paulo, air quality monitoring and for estimation of humidity impact on the aerosol optical properties, without any a priori assumption. This study will present the first results obtained with this upgraded LIDAR system, demonstrating the high quality of obtained aerosol and water vapor data. For that purpose, we compared the data obtained with the new MSP-Raman LIDAR with a mobile Raman LIDAR collocated at the Center for Lasers and Applications, Nuclear and Energy Research Institute in São Paulo and radiosonde data from Campo de Marte Airport, in São Paulo.

Landulfo, Eduardo; Rodrigues, Patrícia F.; da Silva Lopes, Fábio Juliano; Bourayou, Riad

2012-11-01

5

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

6

Raman Lidar Measurements of Aerosol Extinction and Backscattering. Report 1; Methods and Comparisons  

NASA Technical Reports Server (NTRS)

This paper examines the aerosol backscattering and extinction profiles measured at night by the NASA Goddard Space Flight Center Scanning Raman Lidar (SRL) during the remote cloud sensing (RCS) intensive operations period (IOP) at the Department of Energy Atmospheric Radiation Measurement (ARM) southern Great Plains (SGP) site in April 1994. These lidar data are used to derive aerosol profiles for altitudes between 0.0 1 5 and 5 km. Since this lidar detects Raman scattering from nitrogen and oxygen molecules as well as the elastic scattering from molecules and aerosols, it measures both aerosol backscattering and extinction simultaneously. The aerosol extinction/backscattering ratio varied between approximately 30 sr and 75 sr at 351 nm. Aerosol optical thicknesses derived by integrating the lidar profiles of aerosol extinction measured at night between 0. I and 5 km are found to be about 10-40% lower than those measured by a Sun photometer during the day. This difference is attributed to the contribution by stratospheric aerosols not included in the lidar estimates as well as to diurnal differences in aerosol properties and concentrations. Aerosol profiles close to the surface were acquired by pointing the lidar nearly horizontally. 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 reasons for this difference are not clear but may be due to the inability of the nephelometer to accurately measure scattering by large particles.

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

1998-01-01

7

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

NASA Technical Reports Server (NTRS)

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

Whiteman, David N.

2003-01-01

8

Mie-Rayleigh-Raman lidar for measurement of atmospheric temperature and aerosol extinction  

Microsoft Academic Search

A Mie-Rayleigh-Raman lidar contains a 200mJ-532nm laser, a 400mm telescope and three detection channels was constructed in this paper. The three detection channels are Mie channel, Rayleigh channel and Raman channel respectively. For the intensity of the aerosol backscattering in boundary layers, analog PMT is used in the Mie channel, from the signal of the analog PMT aerosol extinction can

Lingbing Bu; Xingyou Huang; Nianwen Cao; Jiansong Huang; Li Guan; Kunling Shan

2009-01-01

9

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

SciTech Connect

We have developed and implemented automated algorithms to retrieve profiles of water vapor mixing ratio, aerosol backscattering, and aerosol extinction from Southern Great Plains (SGP) Cloud and Radiation Testbed (CART) Raman Lidar data acquired during both daytime and nighttime operations. This Raman lidar system is unique in that it is turnkey, automated system designed for unattended, around-the-clock profiling of water vapor and aerosols (Goldsmith et al., 1998). These Raman lidar profiles are important for determining the clear-sky radiative flux, as well as for validating the retrieval algorithms associated with satellite sensors. Accurate, high spatial and temporal resolution profiles of water vapor are also required for assimilation into mesoscale models to improve weather forecasts. We have also developed and implemented routines to simultaneously retrieve profiles of relative humidity. These routines utilize the water vapor mixing ratio profiles derived from the Raman lidar measurements together with temperature profiles derived from a physical retrieval algorithm that uses data from a collocated Atmospheric Emitted Radiance Interferometer (AERI) and the Geostationary Operational Environmental Satellite (GOES) (Feltz et al., 1998; Turner et al., 1999). These aerosol and water vapor profiles (Raman lidar) and temperature profiles (AERI+GOES) have been combined into a single product that takes advantage of both active and passive remote sensors to characterize the clear sky atmospheric state above the CART site.

FERRARE,R.A.

2000-01-09

10

Raman lidar profiling of water vapor and aerosols over the ARM SGP Site  

SciTech Connect

The authors have developed and implemented automated algorithms to retrieve profiles of water vapor mixing ratio, aerosol backscattering, and aerosol extinction from Southern Great Plains (SGP) Cloud and Radiation Testbed (CART) Raman Lidar data acquired during both daytime and nighttime operations. The Raman lidar sytem is unique in that it is turnkey, automated system designed for unattended, around-the-clock profiling of water vapor and aerosols. These Raman lidar profiles are important for determining the clear-sky radiative flux, as well as for validating the retrieval algorithms associated with satellite sensors. Accurate, high spatial and temporal resolution profiles of water vapor are also required for assimilation into mesoscale models to improve weather forecasts. The authors have also developed and implemented routines to simultaneously retrieve profiles of relative humidity. These routines utilize the water vapor mixing ratio profiles derived from the Raman lidar measurements together with temperature profiles derived from a physical retrieval algorithm that uses data from a collocated Atmospheric Emitted Radiance Interferometer (AERI) and the Geostationary Operational Environmental Satellite (GOES). These aerosol and water vapor profiles (Raman lidar) and temperature profiles (AERI+GOES) have been combined into a single product that takes advantage of both active and passive remote sensors to characterize the clear sky atmospheric state above the CART site.

Ferrare, R.A.

2000-01-09

11

Improved method to retrieve aerosol optical properties from combined elastic backscatter and Raman lidar data  

NASA Astrophysics Data System (ADS)

An improved method that has the potential to improve the retrieval of aerosol optics properties (backscatter/extinction coefficients) from elastic-Raman lidar data is presented. Aerosol backscatter coefficients can be retrieved by choosing the reference height at near-range rather than conventional far-range when the signal-to-noise ratios are low at the far-range or aloft aerosol layers and clouds appear there. Significant retrieval errors in aerosol backscatter coefficients caused by large uncertainties of the aerosol reference value at far-range can be reduced. To avoid the ill-posed retrievals of aerosol extinction from the conventional Raman method, the new method derives the aerosol extinction and lidar ratio with the constrained Fernald inversions by independent aerosol backscatter coefficients from above proposed method. The numerical simulations demonstrated that the proposed method provides good accuracy and resolution of aerosol profile retrievals. And the method is also applied to elastic-Raman lidar measurements at the Hampton University, Hampton, Virginia.

Su, Jia; Wu, Yonghua; McCormick, M. Patrick; Lei, Liqiao; Lee, Robert B.

2014-07-01

12

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

2005-04-01

13

Portable standoff Raman and Mie-Rayleigh lidar for cloud, aerosol, and chemical monitoring  

Microsoft Academic Search

There is a need for portable, low-cost lidar systems that can be used for cloud, aerosols and chemical monitoring from a stand-off distance. At the University of Hawaii we have developed lidar systems based on a 12.7-cm diameter telescope and a 20 Hz frequency-doubled Nd:YAG laser source. For stand off Raman detection of organic liquid and vapors, and plastic explosives,

Shiv K. Sharma; John N. Porter; Anupum K. Misra; Hugh W. Hubble; Premlata Menon

2003-01-01

14

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

15

Raman lidar measurements of Pinatubo aerosols over southeastern Kansas during November-December 1991  

NASA Technical Reports Server (NTRS)

The eruptions of the Philippine volcano Pinatubo during June 1991 produced large amounts of stratospheric aerosols that could significantly affect earth's climate as well as trigger stratospheric ozone depletion through heterogeneous chemical reactions. Information regarding the physical and optical properties of these aerosols is required to quantify those effects. By measuring both the elastically backscattered signal and the inelastic signal produced by Raman scattering from nitrogen molecules, Raman lidar can provide some of this information. In this presentation we discuss Raman lidar measurements of the scattering ratio, backscattering, extinction, extinction/backscattering ratio, and optical thickness of the Pinatubo aerosols over southeastern Kansas made on 10 nights during November and December, 1991. The Raman lidar developed at GSFC is a trailer-based system which uses an XeF excimer laser to transmit light at 351 nm. The light backscattered by molecules and aerosols at this wavelength is detected as well as Raman scattered light from water vapor, nitrogen, and oxygen molecules. Since background skylights interfere with the detection of the Raman signals the data discussed in this paper were acquired only at night.

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

1992-01-01

16

Typical tropospheric aerosol backscatter profiles for Southern Ireland: The Cork Raman lidar  

NASA Astrophysics Data System (ADS)

A Raman lidar instrument (UCLID) was established at the University College Cork as part of the European lidar network EARLINET. Raman backscatter coefficients, extinction coefficients and lidar ratios were measured within the period 28/08/2010 and 24/04/2011. Typical atmospheric scenarios over Southern Ireland in terms of the aerosol load in the planetary boundary layer are outlined. The lidar ratios found are typical for marine atmospheric condition (lidar ratio ca. 20-25 sr). The height of the planetary boundary layer is below 1000 m and therefore low in comparison to heights found at other lidar sites in Europe. On the 21st of April a large aerosol load was detected, which was assigned to a Saharan dust event based on HYSPLIT trajectories and DREAM forecasts along with the lidar ratio (70 sr) for the period concerned. The dust was found at two heights, pure dust at 2.5 km and dust mixing with pollution from 0.7 to 1.8 km with a lidar ratio of 40-50 sr.

McAuliffe, Michael A. P.; Ruth, Albert A.

2013-02-01

17

An investigation of Raman lidar aerosol measurements and their application to the study of the aerosol indirect effect  

NASA Astrophysics Data System (ADS)

The problem of the increasing global atmospheric temperature has motivated a large interest in studying the mechanisms that can influence the radiative balance of the planet. Aerosols are responsible for several radiative effects in the atmosphere: an increase of aerosol loading in the atmosphere increases the reflectivity of the atmosphere and has an estimated cooling effect and is called the aerosol direct effect. Another process involving aerosols is the effect that an increase in their concentration in the atmosphere has on the formation of clouds and is called the aerosol indirect effect. In the latest IPCC report, the aerosol indirect effect was estimated to be responsible for a radiative forcing ranging between -0.3 W/m2 to -1.8 W/m2, which can be as large as, but opposite in sign to, the radiative forcing due to greenhouse gases. The main goal of this dissertation is to study the Raman lidar measurements of quantities relevant for the investigation of the aerosol indirect effect and ultimately to apply these measurements to a quantification of the aerosol indirect effect. In particular we explore measurements of the aerosol extinction from both the NASA Goddard Space Flight Center Scanning Raman Lidar (SRL) and the US Department of Energy (DOE) ARM Climate Research Facility Raman Lidar (CARL). An algorithm based on the chi-squared technique to calculate the aerosol extinction, which was introduced first by Whiteman (1999), is here validated using both simulated and experimental data. It has been found as part of this validation that the aerosol extinction uncertainty retrieved with this technique is on average smaller that the uncertainty calculated with the technique traditionally used. This algorithm was then used to assess the performance of the CARL aerosol extinction retrieval for low altitudes. Additionally, since CARL has been upgraded with a channel for measuring Raman liquid water scattering, measurements of cloud liquid water content, droplet radius and droplet number density using this new capability have been studied. Some discrepancies are found between the CARL and AERI measurements of liquid water path and droplet effective radius and they need to be studied in more detail when a larger dataset is available. To study the correlation between aerosol presence and cloud microphysics the calculations of IE, introduced by Feingold as a parameterization of the aerosol indirect effect, has been performed here for the first time using exclusively Raman lidar data. The work shown here is an indication that the combined measurements of aerosol extinction, cloud liquid water content, droplet radius and droplet number density with a Raman lidar represents an interesting new technique for the study of the aerosol indirect effect.

Russo, Felicita

18

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

19

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

NASA Technical Reports Server (NTRS)

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

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

2002-01-01

20

Mie-Rayleigh-Raman lidar for measurement of atmospheric temperature and aerosol extinction  

NASA Astrophysics Data System (ADS)

A Mie-Rayleigh-Raman lidar contains a 200mJ-532nm laser, a 400mm telescope and three detection channels was constructed in this paper. The three detection channels are Mie channel, Rayleigh channel and Raman channel respectively. For the intensity of the aerosol backscattering in boundary layers, analog PMT is used in the Mie channel, from the signal of the analog PMT aerosol extinction can be obtained. The Rayleigh channel detects the Rayleigh backscattering of the atmospheric molecular, while the Raman channel detects the vibrational Raman signal of N2, which is 607nm in the system. From the Rayleigh and Raman channels above, air density profile and then the temperature profile from 5Km to 55Km can be inverted. Primary measurement results were also presented in this paper, to verify the accuracy of the temperature, comparison was conducted between the lidar measurement and the atmospheric model. The result showed good agreements. Backscattering coefficient of aerosol in the range of 10Km was also presented in the end, which indicated the ability of aerosol monitoring.

Bu, Lingbing; Huang, Xingyou; Cao, Nianwen; Huang, Jiansong; Guan, Li; Shan, Kunling

2009-07-01

21

Comparisons of Aerosol-Cloud Observations Between a Ground-based Raman-Mie Lidar and CALIPSO  

NASA Astrophysics Data System (ADS)

Global vertical profiles of aerosol and cloud are currently being observed by satellite CALIPSO. Based on the inherent properties of elastic-scattering lidar, the lidar ratio (extinction-to-backscatter ratio) becomes very important to quantitatively retrieve the distribution of aerosol/cloud extinction or backscatter coefficient. In this presentation, we examine the feasibility of using MODIS-retrieved aerosol optical depth over ocean to constrain the aerosol lidar ratio in the CALIPSO retrieval of aerosol extinction profile with Fernald algorithm, and then compare these lidar-ratios to those derived from both column measurements by the CIMEL Sunphotometer and a combination of the ground-based lidar and radiometer. We explore the variability of lidar ratios for the different types of aerosol over the US east coast. In addition, we present our validation measurements for aerosol vertical profiles. So far, 13 near simultaneous observations by our ground-based multi-wavelength Raman-Mie lidar which operated in New York City (40.821N, 73.949W), have been obtained together with other supporting measurements. In particular, comparisons of aerosol extinction profiles are performed between the ground- based lidar and CALIPSO observations and the vertical distribution of smoke plumes, aloft aerosol layer, urban aerosol and PBL height are presented and compared. Retrievals of optically thin clouds heights and optical depth in the low- and high-altitude from CALIPSO and MODIS/Aqua, respectively, are examined with respect to ground- based lidar measurements and several biases in the measurements are presented.

Wu, Y.; Chaw, S.; Gross, B.; Charles, L.; Vladutescu, V.; Cao, N.; Moshary, F.; Ahmed, S.

2007-12-01

22

Water Measurements using a Raman Lidar  

NASA Technical Reports Server (NTRS)

The research record for the usefulness of Raman Lidar in addressing a broad range of important atmospheric research topics is well established. Raman lidar technology has been used to measure tropospheric aerosols, stratospheric aerosols and cirrus clouds. Arguably the most important measurements offered by Raman lidar for both dynamic and radiative studies, however, is that of water vapor. We will describe large improvements in Raman lidar measurements of water vapor made possible through recent technology upgrades. Furthermore, we will present the use of Raman lidar to study liquid water in the atmosphere and describe current research into the use of Raman lidar measurements to estimate ice water content of cirrus clouds.

Whiteman, D. N.; Demoz, B.; Wang, Z.; Veselovskii, I.; Evans, K.; DiGirolamo, P.

2002-01-01

23

Raman lidar system for the measurement of water vapor and aerosols in the earth's atmosphere  

NASA Technical Reports Server (NTRS)

A nighttime operating Raman lidar system that is designed for the measurement of high vertical and temporal resolution profiles of the water vapor mixing ratio and the aerosol backscattering ratio is described. The theory of the measurements is presented. Particular attention is given to operational problems that have been solved during the development of the system. Data are presented from Sept. 1987 and described in their meteorological context.

Whiteman, D. N.; Melfi, S. H.; Ferrare, R. A.

1992-01-01

24

Vertical Profiling of Atmospheric Backscatter with a Raman-Aerosol Lidar  

NASA Astrophysics Data System (ADS)

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

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

2010-01-01

25

Portable standoff Raman and Mie-Rayleigh lidar for cloud, aerosol, and chemical monitoring  

NASA Astrophysics Data System (ADS)

There is a need for portable, low-cost lidar systems that can be used for cloud, aerosols and chemical monitoring from a stand-off distance. At the University of Hawaii we have developed lidar systems based on a 12.7-cm diameter telescope and a 20 Hz frequency-doubled Nd:YAG laser source. For stand off Raman detection of organic liquid and vapors, and plastic explosives, we are using a 0.25-m HoloSpec f/2.2 spectrometer equipped with a gated intensified detector (PI Model I-MAX-1024-E). The samples of interest are excited with 532-nm laser light (35 mJ/pulse). The operational range of the Raman system is in 10's of meters and has been tested at distance of 66 m. This system can also be operated as a Raman lidar by using appropriate filters for atmospheric nitrogen, oxygen and other gaseous species of interest. The Mie-Rayleigh lidar system uses the same telescope and laser, but we have three (1064, 532 and 355-nm) wavelengths available for monitoring clouds and aerosols. A small Hamamatsu H6779 photomultiplier tube (PMT) located near the focal point of telescope detects 532-nm backscatter signal. An avalanche photodiode (APD, EG & G C3095) detector equipped with a 2.5-cm diameter aspheric lens is used for detecting 1064-nm backscatter. The Mie-Rayleigh lidar has usable range of 60 - 4000 m. Results obtained with this system for marine aerosols and clouds are discussed.

Sharma, Shiv K.; Porter, John N.; Misra, Anupum K.; Hubble, Hugh W.; Menon, Premlata

2003-12-01

26

Four-year aerosol observations with a Raman lidar at Thessaloniki, Greece, in the framework of European Aerosol Research Lidar Network (EARLINET)  

NASA Astrophysics Data System (ADS)

Regular aerosol extinction and backscatter measurements using a UV Raman lidar have been performed from January 2001 to December 2004 at Thessaloniki, Greece (40.5°N, 22.9°E), in the framework of the European Aerosol Research Lidar Network (EARLINET). Profiles of the aerosol extinction coefficient, backscatter coefficient, and extinction-to-backscatter ratio (so-called "lidar ratio") were acquired under nighttime conditions and have been used for statistical investigations. The statistical analysis was made both for the planetary boundary layer and for the free troposphere. It was found that the 4-year mean boundary layer particle optical depth at 355 nm was 0.44 ± 0.18, and the total aerosol optical depth was 0.63 ± 0.27. Free tropospheric particles account on the average for 30% of the total aerosol optical depth, ranging from 5% (clean free troposphere conditions) to 55% (mainly Saharan dust events). For the cases examined, the integral of the lidar-derived extinction coefficient was in good agreement with colocated aerosol optical depth measurements at 355 nm obtained with a Brewer spectroradiometer. The mean value of the lidar ratio at 355 nm derived, for the period of measurements at Thessaloniki, was 40 sr with a standard deviation of 21 sr. Mean height profiles of the particle lidar ratio, extinction, and backscatter coefficients are shown along with their seasonal dependence, showing a significant seasonal variability in the free troposphere. An analysis of the data using back trajectories showed also a dependence of the aerosol optical depth and the lidar ratio on the origin of the air mass, with higher values mostly corresponding to air masses originating from the northeast Balkans and eastern Europe.

Amiridis, V.; Balis, D. S.; Kazadzis, S.; Bais, A.; Giannakaki, E.; Papayannis, A.; Zerefos, C.

2005-11-01

27

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

NASA Technical Reports Server (NTRS)

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

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

2008-01-01

28

CART and GSFC Raman lidar measurements of atmospheric aerosol backscattering and extinction profiles for EOS validation and ARM radiation studies  

SciTech Connect

The aerosol retrieval algorithms used by the Moderate-Resolution Imaging Spectroradiometer (MODIS) and Multi-Angle Imaging SpectroRadiometer (MISR) sensors on the Earth Observing Satellite (EOS) AM-1 platform operate by comparing measured radiances with tabulated radiances that have been computed for specific aerosol models. These aerosol models are based almost entirely on surface and/or column averaged measurements and so may not accurately represent the ambient aerosol properties. Therefore, to validate these EOS algorithms and to determine the effects of aerosols on the clear-sky radiative flux, the authors have begun to evaluate the vertical variability of ambient aerosol properties using the aerosol backscattering and extinction profiles measured by the Cloud and Radiation Testbed (CART) and NASA Goddard Space Flight Center (GSFC) Raman Lidars. Using the procedures developed for the GSFC Scanning Raman Lidar (SRL), the authors have developed and have begun to implement algorithms for the CART Raman Lidar to routinely provide profiles of aerosol extinction and backscattering during both nighttime and daytime operations. Aerosol backscattering and extinction profiles are computed for both lidar systems using data acquired during the 1996 and 1997 Water Vapor Intensive Operating Periods (IOPs). By integrating these aerosol extinction profiles, they derive measurements of aerosol optical thickness and compare these with coincident sun photometer measurements. They also use these measurements to measure the aerosol extinction/backscatter ratio S{sub a} (i.e. lidar ratio). Furthermore, they use the simultaneous water vapor measurements acquired by these Raman lidars to investigate the effects of water vapor on aerosol optical properties.

Ferrare, R.A. [National Aeronautics and Space Administration, Hampton, VA (United States). Langley Research Center; Turner, D.D. [Pacific Northwest National Lab., Richland, WA (United States); Melfi, S.H.; Evans, K.D. [Univ. of Maryland, Baltimore, MD (United States); Whiteman, D.N.; Schwemmer, G. [National Aeronautics and Space Administration, Greenbelt, MD (United States); Goldsmith, J.E.M.; Tooman, T. [Sandia National Labs., Livermore, CA (United States)

1998-04-01

29

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

30

Optical properties of different aerosol types: seven years of combined Raman-elastic backscatter lidar measurements in Thessaloniki, Greece  

NASA Astrophysics Data System (ADS)

We present our combined Raman/elastic backscatter lidar observations which were carried out at the EARLINET station of Thessaloniki, Greece, during the period 2001-2007. The largest optical depths are observed for Saharan dust and smoke aerosol particles. For local and continental polluted aerosols the measurements indicate high aerosol loads. However, measurements associated with the local path indicate enhanced aerosol load within the Planetary Boundary Layer. The lowest value of aerosol optical depth is observed for continental aerosols, from West directions with less free tropospheric contribution. The largest lidar ratios, of the order of 70 sr, are found for biomass burning aerosols. A significant and distinct correlation between lidar ratio and backscatter related Ångström exponent values were estimated for different aerosol categories. Scatter plot between lidar ratio values and Ångström exponent values for local and continental polluted aerosols does not show a significant correlation, with a large variation in both parameters possibly due to variable absorption characteristics of these aerosols. Finally for continental aerosols with west and northwest directions that follow downward movement when arriving at our site constantly low lidar ratios almost independent of size are found.

Giannakaki, E.; Balis, D. S.; Amiridis, V.; Zerefos, C.

2010-05-01

31

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

32

Raman lidar and sun photometer measurements of aerosols and water vapor during the ARM RCS experiment  

NASA Technical Reports Server (NTRS)

The first Atmospheric Radiation Measurement (ARM) Remote Cloud Study (RCS) Intensive Operations Period (IOP) was held during April 1994 at the Southern Great Plains (SGP) Cloud and Radiation Testbed (CART) site near Lamont, Oklahoma. This experiment was conducted to evaluate and calibrate state-of-the-art, ground based remote sensing instruments and to use the data acquired by these instruments to validate retrieval algorithms developed under the ARM program. These activities are part of an overall plan to assess general circulation model (GCM) parameterization research. Since radiation processes are one of the key areas included in this parameterization research, measurements of water vapor and aerosols are required because of the important roles these atmospheric constituents play in radiative transfer. Two instruments were deployed during this IOP to measure water vapor and aerosols and study their relationship. The NASA/Goddard Space Flight Center (GSFC) Scanning Raman Lidar (SRL) acquired water vapor and aerosol profile data during 15 nights of operations. The lidar acquired vertical profiles as well as nearly horizontal profiles directed near an instrumented 60 meter tower. Aerosol optical thickness, phase function, size distribution, and integrated water vapor were derived from measurements with a multiband automatic sun and sky scanning radiometer deployed at this site.

Ferrare, R. A.; Whiteman, D. N.; Melfi, S. H.; Evans, K. D.; Holben, B. N.

1995-01-01

33

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

34

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

NASA Technical Reports Server (NTRS)

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

Whiteman, David N.

2003-01-01

35

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

36

Validation of Temperature Measurements from the Airborne Raman Ozone Temperature and Aerosol Lidar During SOLVE  

NASA Technical Reports Server (NTRS)

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 approximately 60 kilometers geometric altitude with a reported vertical resolution of between 0.5 and 1.5 km. The horizontal footprint varied from 4 to 70 km. This paper explores the measurement uncertainties associated with the temperature retrievals and makes comparisons with independent, coincident, measurements of temperature. Measurement uncertainties range from 0.1 K to approximately 4 K depending on altitude and integration time. Comparisons between AROTEL and balloon sonde temperatures retrieved under clear sky conditions using both Rayleigh and Raman scattered data showed AROTEL approximately 1 K colder than sonde values. Comparisons between AROTEL and the Meteorological Measurement System (MMS) on NASA's ER-2 show AROTEL being from 2-3 K colder for altitudes ranging from 14 to 18 km. Temperature comparisons between AROTEL and the United Kingdom Meteorological Office's model showed differences of approximately 1 K below approximately 25 km and a very strong cold bias of approximately 12 K at altitudes between 30 and 35 km.

Burris, John; McGee, Thomas; Hoegy, Walter; Lait, Leslie; Twigg, Laurence; Sumnicht, Grant; Heaps, William; Hostetler, Chris; Bui, T. Paul; Neuber, Roland; Bhartia, P. K. (Technical Monitor)

2001-01-01

37

Raman Lidar Observations from the ARM Site in Darwin, Australia: A Water Vapor and Aerosol Climatology  

NASA Astrophysics Data System (ADS)

The U.S. Department of Energy's Atmospheric Radiation Measurement (ARM) Tropical Western Pacific (TWP) site in Darwin, Australia, collects data over a range of different synoptic regimes in the tropics. Funding from the American Recovery and Reinvestment Act enabled the installation of a new Raman Lidar (RL) at the ARM TWP site in Darwin, Australia. It is the only operational RL in the tropics and the only active remote sensing instrument capable of providing simultaneous measurements of water vapor, clouds, and aerosols at the Darwin site. Thus, it provides important climatological information for better characterization of atmospheric conditions around the TWP region. This study uses 18 months of data from the RL to develop an aerosol and water vapor climatology in the Darwin region. Darwin experiences three distinct climate patterns annually, comprising of 1) a dry continental regime, 2) a wet monsoon season, and 3) a transition period between the dry and wet seasons. The RL observations were separated into different synoptic classes using the technique developed by Evans et al. (2012), and the mean and standard deviation profiles of water vapor mixing ratio and aerosol properties during these three distinct climate regimes will be presented. The median water vapor mixing ratio for the three Darwin climate regimes is shown in figure 1. The lower panel shows the interquartile spread in mixing ratio between the 75th and 25th percentile. Aerosol climatology and comparison of RL derived water vapor mixing ratio profiles with profiles derived from radiosondes will be presented at the conference. Diurnal differences in the distribution of water vapor and aerosols will also be shown. Figure 1: The top panel shows the median RL mixing ratio profiles for the three climate regimes in Darwin (1-dry, 2-transition, 3- wet/monsoon). The bottom panel shows the mixing ratio interquartile spread for the three states. N denotes the number of profiles for each state.

Mishra, S.; Turner, D. D.; Newsom, R. K.; Ferrare, R. A.; Goldsmith, J. E.

2013-12-01

38

Feasibility study of integral property retrieval for tropospheric aerosol from Raman lidar data using principal component analysis.  

PubMed

A method is introduced to derive integral properties of the aerosol size distribution, e.g., aerosol mass, from tropospheric multiwavelength Raman lidar aerosol extinction and backscatter data, using an adapted form of the principal component analysis (PCA) technique. Since the refractive index of general tropospheric aerosols is variable and aerosol types can vary within one profile, an inversion technique applied in the troposphere should account for varying aerosol refractive indices. Using PCA, if a sufficiently complete set of appropriate refractive index dependent kernels is used, no a priori information about the aerosol type is necessary for the inversion of integral properties. In principle, the refractive index itself can be retrieved, but this quantity is more sensitive to measurement errors than the various integral properties of the aerosol size distribution. Here, the PCA technique adapted for use in the troposphere is introduced, the refractive index information content of the kernel sets is investigated, and error analyses are presented. The technique is then applied to actual tropospheric Raman lidar measurements. PMID:23545974

de Graaf, Martin; Apituley, Arnoud; Donovan, David P

2013-04-01

39

Implementation of Raman lidar for profiling of atmospheric water vapor and aerosols at the SGP CART site  

SciTech Connect

There are clearly identified scientific requirements for continuous profiling of atmospheric water vapor at the SGP CART (southern great plains cloud and radiation testbed) site. Research conducted at several laboratories, including our own collaboration in a previous ARM Instrument Development Project, has demonstrated the suitability of Raman lidar for providing measurements that are an excellent match to those requirements. We are currently building a ruggedized Raman lidar system that will reside permanently at the CART site, and that is computer-automated to minimize requirements for operator interaction. In addition to profiling water vapor through most of the troposphere during nighttime and through the boundary layer during daytime, the lidar will provide quantitative characterizations of aerosols and clouds, including depolarization measurements for particle phase studies.

Goldsmith, J.E.M.; Bisson, S.E.; Blair, F.H. [Sandia National Labs., Livermore, CA (United States); Whiteman, D.N.; Melfi, S.H. [National Aeronautics and Space Administration, Greenbelt, MD (United States). Goddard Space Flight Center; Ferrare, R.A. [Hughes STX Corp., Lanham, MD (United States)

1994-05-01

40

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

NASA Astrophysics Data System (ADS)

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

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

2008-04-01

41

Multiyear aerosol observations with dual-wavelength Raman lidar in the framework of EARLINET  

Microsoft Academic Search

For the first time, a Raman lidar operating simultaneously in the ultraviolet (UV) and in the visible wavelength range was employed to measure vertical profiles of volume extinction coefficients of particles at 355 and 532 nm, the respective Ångström exponent, and the 355–nm and 532–nm extinction–to–backscatter ratio (lidar ratio) on a routine basis for several years. The long–term observations were

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

2004-01-01

42

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

43

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

Microsoft Academic Search

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

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

2010-01-01

44

Final Technical Report. Cloud and Radiation Testbed (CART) Raman Lidar measurement of atmospheric aerosols for the Atmospheric Radiation Measurement (ARM) Program  

SciTech Connect

Vertical profiles of aerosol extinction are required for determination of the effects of aerosols on the clear-sky radiative flux. Since recent studies have demonstrated the inability to compute these profiles on surface aerosol measurements alone, vertical profiles of aerosol optical properties must be acquired to compute aerosol radiative effects throughout the entire atmospheric column. Following the recommendation of the ARM Aerosol Working Group, the investigator developed, evaluated, and implemented algorithms for the CART Raman Lidar to provide profiles of aerosol extinction and backscattering. By virtue of its ability to measure vertical profiles of both aerosol extinction and water vapor simultaneously in the same scattering volume, we used the resulting profiles from the CART Raman Lidar to investigate the impact of water vapor and relative humidity on aerosol extinction throughout the column on a continuous and routine basis. The investigator used these the CART Raman Lidar aerosol extinction and backscattering profiles to evaluate the vertical variability of aerosol extinction and the extinction/backscatter ratio over the ARM SGP site.

Ferrare, Richard A.

2002-08-19

45

RAMSES: German Meteorological Service autonomous Raman lidar for water vapor, temperature, aerosol, and cloud measurements.  

PubMed

The Raman lidar for atmospheric moisture sensing (RAMSES) for unattended, continuous multiparameter atmospheric profiling is presented. A seeded frequency-tripled Nd:YAG laser serves as the light source. A nine-channel polychromator, nonfiber coupled to the main telescope (790 mm diameter), is used for far-range measurements. Near-range observations are performed with a three-channel polychromator, fiber coupled to a secondary telescope (200 mm diameter). Measurement parameters are water-vapor mixing ratio (MR), temperature, and the optical particle parameters, which are extinction coefficient, backscatter coefficient, lidar ratio, and depolarization ratio at 355 nm. Profiles of water-vapor MR are measured from close to the surface up to 14 km at night and 5 km during the day under favorable atmospheric conditions in 20 min. Temperature profiles of the troposphere and lower stratosphere are determined with the rotational-Raman technique. For the detection of the rotational Raman signals, a new beamsplitter/interference-filter experimental setup is implemented that is compact, robust, and easy to align. Furthermore, the polychromator design allows two independent methods for calibrating measurements of depolarization ratio. RAMSES optical design concept and experimental setup are detailed, and a description of the operational near-real-time data evaluation software is given. A multiday observation is discussed to illustrate the measurement capabilities of RAMSES. PMID:23207381

Reichardt, Jens; Wandinger, Ulla; Klein, Volker; Mattis, Ina; Hilber, Bernhard; Begbie, Robert

2012-12-01

46

Comparisons of Aerosol-Cloud Observations Between a Ground-based Raman-Mie Lidar and CALIPSO  

Microsoft Academic Search

Global vertical profiles of aerosol and cloud are currently being observed by satellite CALIPSO. Based on the inherent properties of elastic-scattering lidar, the lidar ratio (extinction-to-backscatter ratio) becomes very important to quantitatively retrieve the distribution of aerosol\\/cloud extinction or backscatter coefficient. In this presentation, we examine the feasibility of using MODIS-retrieved aerosol optical depth over ocean to constrain the aerosol

Y. Wu; S. Chaw; B. Gross; L. Charles; V. Vladutescu; N. Cao; F. Moshary; S. Ahmed

2007-01-01

47

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

48

Raman Lidar Retrievals of Mixed Layer Heights  

NASA Astrophysics Data System (ADS)

Accurate determination of the atmospheric mixing layer (ML) height is important for modeling the transport of aerosols and aerosol precursors and forecasting air quality. Aerosol and water vapor profiles measured by the DOE ARM SGP and the new TWP (Darwin) ground based Raman lidars provide direct measurements of the vertical structure of ML. We have developed automated algorithms to identify sharp gradients in aerosols and water vapor at the top of the ML and have used these algorithms to derive ML heights for extended periods over the last few years. During the afternoon, these ML heights generally compare favorably with ML heights derived from potential temperature profiles derived from coincident radiosondes. However, retrieving ML heights via lidar measurements of water vapor and aerosol gradients is problematic in the presence of elevated aerosol and water vapor layers which are often observed, especially at night. Consequently, we take advantage of recent modifications to these lidars that permit continuous temperature profiling, and compute ML heights using potential temperature profiles derived from Raman lidar and Atmospheric Emitted Radiance Interferometer (AERI) measurements. The resulting ML heights agree well with ML heights derived from radiosondes and provide a more realistic representation of the diurnal ML behavior. We use the Raman lidar aerosol and water vapor profiles and ML heights to derive the fractions of total column precipitable water vapor and aerosol optical thickness within and above the ML and show how the ML heights and these fractions vary with time of day and season. The SGP Raman lidar measurements show that the fraction of the aerosol optical thickness and precipitable water vapor above the ML increases from 30-60% during the day to 60-80% at night. The Darwin Raman lidar measurements reveal a shallow, moist cloud-topped ML with little diurnal variability during the austral summer and deeper ML with more diurnal variability during the austral winter. The Darwin Raman lidar measurements of the diurnal and seasonal variabilities of ML heights and the aerosol and water vapor distributions relative to these ML heights will also be presented.

Ferrare, R. A.; Clayton, M.; Turner, D. D.; Newsom, R. K.; Goldsmith, J.

2012-12-01

49

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

50

Advanced Raman water vapor lidar  

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

51

Aerosol optical properties observed by combined Raman-elastic backscatter lidar in winter 2009 in Pearl River Delta, south China  

NASA Astrophysics Data System (ADS)

present combined Raman and elastic backscatter lidar observations in Zhongshan, PRD (Pearl River Delta), China, during two periods in 2009: one haze period and one moderate pollution period. During the haze period, high Aerosol Optical Depth (AOD) (0.86 and 1.20 at 355 nm) and medium Ångström exponents (1.23 and 1.35 at 355 nm/532 nm) were observed. In the moderate pollution period, the corresponding parameters were comparatively lower with values of 0.83 and 0.74 at 355 nm for AOD and 1.108 and 0.98 at 355 nm/532 nm for Ångström exponent. The mean lidar ratios in the two periods were 64 ± 10 sr and 56 ± 9 sr, respectively, at 355 nm. The Ångström exponent was calculated for the extinction from the wavelength pair 355 nm/532 nm, with high values of around 1.35 for the haze event. The particle size distribution and single-scattering albedo derived from Sun photometer measurements indicate the presence of rather small particles. The 3 day back trajectories from a Hybrid Single-Particle Lagrangian Integrated Trajectory model in the haze period indicate that the air masses in the lower layer were advected from the southeast coast of China, where incomplete combustion of carbonaceous fuels and straw burning are frequently found in Shanghai during the heating period in winter. In the moderate pollution period, the air mass passed through western China, indicating a combination of some pollution from South Asia in case of strong convection, local aerosol aging, and smoke from adjacent fire burning spots in the PRD region.

Chen, Zhenyi; Liu, Wenqing; Heese, Birgit; Althausen, Dietrich; Baars, Holger; Cheng, Tianhai; Shu, Xiaowen; Zhang, Tianshu

2014-03-01

52

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

53

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

NASA Astrophysics Data System (ADS)

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

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

2012-05-01

54

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

55

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+2) Raman lidar measurements at Gual Pahari, close to 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 with 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.

2010-12-01

56

JPL-TMF multiwavelength aerosol lidar  

NASA Technical Reports Server (NTRS)

The JPL-TMF Lidar Facility began operation in 1985 with the completion of a XeCl excimer based stratospheric ozone DIAL system. As an adjunct to this system a Nd:YAG based tropospheric ozone and aerosol system was assembled. The tropospheric ozone system was designed to utilize the fourth harmonic (266 nm) of the Nd:YAG to produce 289 nm, 294 nm or 299 nm by SRS in the isotopic hydrogen gases. The aerosol lidar was developed using the fundamental (1064 nm) and second harmonic of the Nd:YAG (532 nm). Following the eruption of Mount Pinatubo most of the effort was put into obtaining data on the layer structure of the volcanic aerosol as a function of altitude and time on a regular basis. During this period the tropospheric ozone DIAL was not employed on a regular schedule. The stratospheric measurements were of primary interest; however with the volcanic aerosol concentrated at the 16 - 26 km altitude the ozone concentration profile was perturbed. The aerosol interference in the ozone measurements caused the lidar community to seek techniques of measurement of the aerosol which could be used in making realistic corrections to the ozone measurements. It is generally accepted that a reasonable technique of measurement would include at least one channel of Raman scattering from a blue wavelength and a minimum of three other supporting wavelengths. With the primary transmitters available at TMF, a four wavelength system was considered for configuration. The four wavelength aerosol lidar is based on the Nd:YAG fundamental, the second and third harmonics of the transmitter. The receiver will separate these three wavelengths as well as the Raman scattering from atmospheric nitrogen of the third harmonic.

Haner, David A.; McDermid, I. Stuart

1995-01-01

57

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

58

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

59

One-year observations of Mount-Pinatubo aerosol with an advanced Raman lidar over Germany at 53.5 deg N  

NASA Astrophysics Data System (ADS)

Combined Raman elastic-backscatter lidar observations of the development of stratospheric perturbation after eruptions of Mt. Pinatubo in June 1991 yielded height profiles of the particle extinction and backscatter coefficients simultaneously and independently of each other. From these data, the area-weighted mean particle radius and the aerosol surface area and mass are determined. The lidar measurements were taken at Geesthacht in northern Germany. The Pinatubo aerosol layer is located between the tropopause and about 24 km. The ratio of optical depth to column-integrated backscatter varied over 15-60 sr; most values were found at 20-30 sr. Extinction-to-backscatter ratios above 50, between 20 and 30, and below 15 sr, indicate effective particle radii lower than 0.2, between 0.2 and 0.75, and over 0.75 microns, respectively. Variations of the extinction to backscatter ratio with height between about 10 and 90 sr were observed. Column aerosol mass and surface area were of the order of 0.05 g/sq m and 2.5 x 10 exp 11 sq microns/sq m in the first half of 1992.

Ansmann, Albert; Wandinger, Ulla; Weitkamp, Claus

1993-04-01

60

LIDAR Measurements During Aerosols99  

NASA Technical Reports Server (NTRS)

The Aerosols99 cruise took place during the period from January 14, to February 8 1999 on the R/V Ron Brown. The cruise track was almost a straight line from Norfolk, Va. to Cape Town, South Africa and afforded the opportunity to sample several different aerosol regimes over the North and South Atlantic. A Micro Pulse LIDAR system was used continually during this cruise to profile the aerosol vertical structure. Inversions of this data illustrated a varying vertical structure depending on the dominant air mass. In clean maritime aerosols in the Northern and Southern Hemispheres the aerosols were capped at 1 km. When a Dust event from Africa was encountered the aerosol extinction increased its maximum height to above 2 km. During a period in which the air mass was dominated by biomass burning from Southern Africa, the aerosol layer extended to 4 km. Comparisons of the aerosol optical depth derived from LIDAR inversion and surface sunphotometers showed an agreement within +/- 0.05 RMS Similar comparisons between the extinction measured with a nephelometer and particle soot absorption photometer (at 19 m altitude) and the lowest LIDAR measurement (75 m) showed good agreement (+/- 0.014/km . The LIDAR underestimated surface extinction during periods when an elevated aerosol layer was present over a relatively clean surface layer, but otherwise gave accurate results.

Voss, Kenneth J.; Welton, Ellsworth J.; Quinn, Patricia K.; Johnson, James; Thompson, Anne; Einaudi, Franco (Technical Monitor)

2000-01-01

61

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

62

Seasonal characteristics of lidar ratios measured with a Raman lidar at Gwangju, Korea in spring and autumn  

Microsoft Academic Search

Vertical profiles of aerosol lidar ratios at wavelengths of 355 and 532nm were measured with the GIST\\/ADEMRC (Gwangju Institute of Science & Technology\\/ADvanced Environmental Monitoring Research Center) multi-wavelength Raman lidar system at Gwangju, Korea (35.10°N, 126.53°E) during several observation periods between February 2004 and May 2005. The total number of observed aerosol layers was 63, of which 38 and 25

Young M. Noh; Young J. Kim; Detlef Müller

2008-01-01

63

Flight results for the airborne Raman lidar  

NASA Technical Reports Server (NTRS)

The airborne Raman lidar recently completed a series of flight tests aboard a C-130 aircraft operated by the NASA Wallops Flight Facility. The Raman lidar is intended to make simultaneous remote measurements of methane, water vapor, temperature, and pressure. The principal purpose of the measurements is to aid in the investigation of polar phenomena related to the formation of ozone 'holes' by permitting the identification of the origin of air parcels using methane as a tracer.

Heaps, William S.; Burris, John F.

1995-01-01

64

Lidar backscattering measurements of background stratospheric aerosols  

NASA Technical Reports Server (NTRS)

A comparative lidar-dustsonde experiment was conducted in San Angelo, Texas, in May 1974 in order to estimate the uncertainties in stratospheric-aerosol backscatter for the NASA Langley 48-inch lidar system. The lidar calibration and data-analysis procedures are discussed. Results from the Texas experiment indicate random and systematic uncertainties of 35 and 63 percent, respectively, in backscatter from a background stratospheric-aerosol layer at 20 km.

Remsberg, E. E.; Northam, G. B.; Butler, C. F.

1979-01-01

65

Lidar backscattering measurements of background stratospheric aerosols  

Microsoft Academic Search

A comparative lidar-dustsonde experiment was conducted in San Angelo, Texas, in May 1974 in order to estimate the uncertainties in stratospheric-aerosol backscatter for the NASA Langley 48-inch lidar system. The lidar calibration and data-analysis procedures are discussed. Results from the Texas experiment indicate random and systematic uncertainties of 35 and 63 percent, respectively, in backscatter from a background stratospheric-aerosol layer

E. E. Remsberg; G. B. Northam; C. F. Butler

1979-01-01

66

Advanced Aerosol Lidar Ratio Determination Algorithms Using Aerosol Covariance Models  

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

67

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

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

68

Raman lidar and sunphotometric measurements of aerosol optical properties over Thessaloniki, Greece during a biomass burning episode  

Microsoft Academic Search

The influence of biomass burning smoke on the aerosol loading in the free troposphere over Thessaloniki, Greece (40.5°N, 22.9°E) is discussed in this paper. A selected case during summer 2001 is presented, when very high aerosol optical depth values were observed, benefiting from the synergy of various remote sensing instruments. The data that were collected allow the characterization of the

D. S. Balis; V. Amiridis; C. Zerefos; E. Gerasopoulos; M. Andreae; P. Zanis; A. Kazantzidis; S. Kazadzis; A. Papayannis

2003-01-01

69

Measuring Hydrogen Plumes With Raman Lidar  

NASA Technical Reports Server (NTRS)

Prototype Raman lidar system measures concentration of hydrogen gas in atmosphere as function of position, with range resolution of 3 ft over 3,000 ft. Sensitive to concentrations smaller than 0.5 percent, 10 times below minimum flammable concentration. Pulsed ultraviolet laser beam excites Raman emissions from molecules to be detected. Backscattered light collected by telescope, filtered at appropriate wavelengths, and sent to photodetectors. Developed for use as safety monitor, and to study dispersion of hydrogen gas leaking into atmosphere.

Caputo, Bernard

1992-01-01

70

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

71

Modular and mobile multipurpose lidar system for observation of tropospheric and stratospheric aerosols  

Microsoft Academic Search

An aerosol Raman lidar with a frequency doubled and tripled Nd:YAG laser and a 1140 mm diameter receiving telescope is under development for measurements of aerosol backscatter, extinction coefficients and depolarization in the altitude range 5 to 50 km. The light received by the telescope is split according to polarization and fed via glass fibers to a filter polychromator and

Juergen Schafer; Otto Schrems; Georg Beyerle; Bernd Hofer; Wolfgang Mildner; Felix A. Theopold; Wilhelm Lahmann; Claus Weitkamp; Manfred Steinbach

1995-01-01

72

Improvement of NIES lidar network observations by adding Raman scatter measurement function  

NASA Astrophysics Data System (ADS)

We have conducted ground-based lidar network observations in wide areas of East Asia using two-wavelength (532 and 1064nm) backscatter and one-wavelength (532nm) depolarization Mie-scatter lidars for more than ten years. To realize more advanced aerosol classification and retrieval, we improved the Mie-scatter lidars at several main sites by adding a N2 Raman scatter measurement channel (607nm). This Mie-Raman lidar system provides 1?+2?+1? data at nighttime: extinction coefficient (?) at 532nm, backscatter coefficients (?) at 532 and 1064nm, and depolarization ratio (?) at 532nm. We also developed an algorithm to estimate vertical profiles of 532nm extinction coefficients of black carbon, dust, sea-salt, and air-pollution aerosols consisting of a mixture of sulfate, nitrate, and organic carbon substances (SF-NT-OC) using the 1?+2?+1? data. With this method, we assume an external mixture of aerosol components and prescribe their size distributions, refractive indexes, and particle shapes. The measured lidar data are automatically transferred to the NIES data server. We developed an algorithm to estimate particle optical properties (1?+2?+1? data), planetary boundary layer (PBL) height, and scene classification identifiers representing molecule-rich, aerosol-rich, or cloud-rich layer automatically and provide their quick-looks in semi-realtime on the website (http://www-lidar.nies.go.jp/shingakujutsu/Raman/).

Nishizawa, Tomoaki; Sugimoto, Nobuo; Matsui, Ichiro; Shimizu, A.

2012-11-01

73

Tropical stratospheric aerosol layer from CALIPSO lidar observations  

Microsoft Academic Search

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

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

2009-01-01

74

The First Year of Raman Lidar Observations at Darwin  

NASA Astrophysics Data System (ADS)

The U.S. Department of Energy's Atmospheric Radiation Measurement (ARM) Tropical Western Pacific (TWP) site in Darwin, Australia, collects data over a range of different synoptic regimes in the tropics. Darwin experiences three distinct climate patterns annually, comprising of 1) a dry continental regime from May to September; 2) a wet monsoon season from December to March 3) and transition periods in April and October/November. The warmest sea surface temperatures associated with the Pacific warm pool are also observed in the TWP region. Dynamic and thermodynamic forcings associated with the Pacific warm pool significantly affect the atmosphere's general circulation. Thus, the TWP region plays a major role in the global inter-annual climate variability. Funding from the American Recovery and Reinvestment Act enabled the installation of a new Raman Lidar at the ARM TWP site in Darwin. The Raman Lidar (RL) is a laser based active remote sensing instrument that provides continuous vertical profiles of water vapor mixing ratio and several other cloud and aerosol related quantities at high vertical and temporal resolution. Hence RL data provide important climatological information to better characterize atmospheric conditions around the TWP region. The RL at the Darwin site has been operational since December 2010 with occasional downtimes resulting from instrument issues. An overview of the first 18 months of TWP RL data will be presented at the conference. This will include comparisons of RL water vapor profiles with radiosondes, as well as evaluation of aerosol extinction and backscatter. Diurnal differences in the distribution of water vapor and aerosols will also be shown. Based on the synoptic state of the atmosphere, the aerosol and water vapor data from Darwin have been separated into eight distinct states. Climatology of water vapor mixing ratio and aerosol extinction and backscatter based on the synoptic state classification will also be presented.

Mishra, S.; Turner, D. D.; Newsom, R. K.; Evans, S. M.; Goldsmith, J.

2012-12-01

75

Optical properties of Saharan dust layers as detected by a Raman lidar at Thessaloniki, Greece  

Microsoft Academic Search

Measurements during Saharan dust transport events were performed at several stations of the European Aerosol Research Lidar Network. During the period 2001-2002, 12 cases were captured at Thessaloniki, Greece (40.5°N, 22.9°E) with a 355 nm Raman lidar. For these cases the vertical profiles of the extinction and backscatter coefficients were determined and examined, as well as profiles of extinction-to-backscatter ratio

D. S. Balis; V. Amiridis; S. Nickovic; A. Papayannis; C. Zerefos

2004-01-01

76

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

NASA Technical Reports Server (NTRS)

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

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

2002-01-01

77

Automatic gain control for Raman lidar signals  

NASA Astrophysics Data System (ADS)

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

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

2008-12-01

78

Advances in Raman Lidar Measurements of Water Vapor  

NASA Technical Reports Server (NTRS)

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

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

2002-01-01

79

Research on stimulated Raman scattering with applications to atmospheric lidar  

Microsoft Academic Search

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

Zhiping Chu

1991-01-01

80

Fluorescence from atmospheric aerosols observed with a multi-channel lidar spectrometer.  

PubMed

A lidar for measuring fluorescence from atmospheric aerosols was constructed with a third harmonic Nd:YAG laser, a 1-m diameter telescope, and a 32-channel time-resolved photon-counting spectrometer system. Fluorescence spectrum and vertical distribution of fluorescent aerosols in the lower atmosphere were observed during the nighttime with excitation at 355 nm. Relatively strong broad fluorescence was observed from Asian dust and air-pollution aerosols transported from urban and industrial areas. Rough estimates of the fluorescence efficiency were given for these aerosols. The intensity of the total fluorescence over the spectral range from 420 to 510 nm was comparable to that of nitrogen vibrational Raman scattering. That indicates the possibility of making a compact Raman-Mie-fluorescence lidar for aerosol monitoring. PMID:23037203

Sugimoto, Nobuo; Huang, Zhongwei; Nishizawa, Tomoaki; Matsui, Ichiro; Tatarov, Boyan

2012-09-10

81

Seasonal characteristics of lidar ratios measured with a Raman lidar at Gwangju, Korea in spring and autumn  

NASA Astrophysics Data System (ADS)

Vertical profiles of aerosol lidar ratios at wavelengths of 355 and 532 nm were measured with the GIST/ADEMRC (Gwangju Institute of Science & Technology/ADvanced Environmental Monitoring Research Center) multi-wavelength Raman lidar system at Gwangju, Korea (35.10°N, 126.53°E) during several observation periods between February 2004 and May 2005. The total number of observed aerosol layers was 63, of which 38 and 25 were observed in spring and autumn, respectively. Average values of the lidar ratio, Sa, were 55±10 sr and 56±9 sr at 355 and 532 nm, respectively, in spring and 61.4±7.5 sr and 63.1±12.8 sr at 355 and 532 nm, respectively, in autumn. Cases of high lidar ratio values (>65 sr) were observed more frequently in autumn than in spring for 28% and 46% of the time at 355 and 532 nm, respectively. Mean lidar ratio value of 51±6 sr at 532 nm was obtained for Asian dust particles in spring which was lower than those for non-dust (60±10 sr) and smoke (65±8 sr) particles. Very high lidar ratios of 75.3±15.8 sr at 532 nm were observed above the planetary boundary layer (PBL) in autumn. These high values are believed to have largely resulted from an increased amount of light-absorbing particles mostly in the fine mode of the particle size distribution, generated by coal combustion and agricultural biomass burning. Lidar ratios, Ångström exponents and effective radii values retrieved from collocated sunphotometer data were similar to those obtained from Raman lidar measurements.

Noh, Young M.; Kim, Young J.; Müller, Detlef

82

Lidar Aerosol Profiles Measured From Halifax During Summer 2007  

NASA Astrophysics Data System (ADS)

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

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

2007-12-01

83

A combined Raman lidar for low tropospheric studies  

NASA Technical Reports Server (NTRS)

One of the main goals of laser sensing of the atmosphere was the development of techniques and facilities for remote determination of atmospheric meteorological and optical parameters. Of lidar techniques known at present the Raman-lidar technique occupies a specific place. On the one hand Raman lidar returns due to scattering on different molecular species are very simple for interpretation and for extracting the information on the atmospheric parameters sought, but, on the other hand, the performance of these techniques in a lidar facility is overburdened with some serious technical difficulties due to extremely low cross sections of Raman effect. Some results of investigations into this problem is presented which enables the construction of a combined Raman lidar capable of acquiring simultaneously the profiles of atmospheric temperature, humidity, and some optical characteristics in the ground atmospheric layer up to 1 km height. The operation of this system is briefly discussed.

Arshinov, Y. F.; Bobrovnikov, S. M.; Zuev, V. E.; Nadeev, A. I.; Shelevoy, K. D.

1986-01-01

84

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

85

Raman excitation profile of nitrobenzene: prospect of Raman lidar detection  

NASA Astrophysics Data System (ADS)

The absolute values of the Raman scattering cross-section of the 1347 cm-1 NO2 symmetric stretch mode of nitrobenzene vapor were measured at some discrete excitation wavelengths in the range 240 nm to 420 nm. An analytical expression for their wavelength dependence was obtained from the numerical `best fit' of the data to Albrecht `A' term. The Raman excitation profile, thus created, exhibits a strong resonance effect, attributed to the charge-transfer state in C6H5NO2 corresponding to the absorption peak at 240 nm. At near resonance excitation (250 nm) the Raman cross-section was found to be more than two orders of magnitude higher than that expected at the same wavelength from (lambda) -4 dependence. Although the excitation profile remained the same, the vapor phase cross-section values were almost an order of magnitude lower than those measured in liquid phase. The implication of resonance enhancement on the Raman lidar detection of NB vapor was analyzed for a standard atmospheric model with different ozone loadings using LOWTRAN7 computer code.

Ahmad, Sheikh R.; Foster, V. G.

1996-11-01

86

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

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

87

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

NASA Astrophysics Data System (ADS)

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 excimer laser and a frequency-tripled Nd:YAG laser. The received backscattered light is separated in an eight-cahnnel filter polychromator and detected by photomultipliers in single-photon counting mode. Ozone concentrations and aerosol and moisture profiles are obtained by applying the Raman-DIAL and conventional DIAL and the Raman lidar technique, respectively. Aerosol and moisture profiles and derived by applying the common Raman technique. Examples of the measured aerosol, ozone, moisture, and temperature profiles are shown.

Serwazi, Marcus; Reichardt, Jens; Weitkamp, Claus

1995-09-01

88

Aerosol lidar and MODIS satellite comparisons for future aerosol loading forecast  

Microsoft Academic Search

Knowledge of the concentration and distribution of atmospheric aerosols using both airborne lidar and satellite instruments is a field of active research. An aircraft based aerosol lidar has been used to study the distribution of atmospheric aerosols in the California Central Valley and eastern US coast. Concurrently, satellite aerosol retrievals, from the MODIS (Moderate Resolution Imaging Spectroradiometer) instrument aboard the

Russell De Young; James Szykman; Kurt Severance; D. Allen Chu; Rebecca Rosen; Jassim Al-Saadi

2006-01-01

89

Lidar observations of the stratospheric aerosols at Bandung, Indonesia  

NASA Astrophysics Data System (ADS)

We installed a lidar system for observations of the stratospheric aerosols at Bandung, Indonesia on November 1996. The system employed the second harmonic wavelength (532 nm) of Nd:YAG laser. We can measure scattering ratio and depolarization of 532 nm, and Raman scattering of N2 (607 nm). The system works well and the stratospheric aerosols were detected between 18 km and about 35 km. Cirrus clouds are always observed between 10 km and tropopause and area around tropopause is clear except for cloud-like structures. Integrated backscattering coefficient (IBC) of the stratospheric aerosols in 1997 is about 6 X 10-5sr-1 level and smaller than the value observed in mid-latitude, corresponding to the higher tropopause in the equatorial region. Variation of IBC at Bandung seems to be small. It is yet not clear whether current aerosol load is background level or not. We need more long period observations to discuss about seasonal, QBO, and long term variation of aerosol load.

Mizutani, Kohei; Itabe, Toshikasu; Yasui, Motoaki; Aoki, Tetsuo; Nagai, Tomohiro; Fujimoto, Toshifumi; Hirota, Masao; Uchino, Osamu; Nuryanto, Agus; Kaloka Prabotosari, Sri; Hamdi, Saipul

1998-08-01

90

Comparison of Aerosol Optical Properties and Water Vapor Among Ground and Airborne Lidars and Sun Photometers During TARFOX  

NASA Technical Reports Server (NTRS)

We compare aerosol optical thickness (AOT) and precipitable water vapor (PWV) measurements derived from ground and airborne lidars and sun photometers during the Tropospheric Aerosol Radiative Forcing Observational Experiment. Such comparisons are important to verify the consistency between various remote sensing measurements before employing them in any assessment of the impact of aerosols on the global radiation balance. Total scattering ratio and extinction profiles measured by the ground-based NASA Goddard Space Flight Center scanning Raman lidar system, which operated from Wallops Island, Virginia (37.86 deg N, 75.51 deg W); are compared with those measured by the Lidar Atmospheric Sensing Experiment (LASE) airborne lidar system aboard the NASA ER-2 aircraft. Bias and root-mean-square differences indicate that these measurements generally agreed within about 10%. Aerosol extinction profiles and estimates of AOT are derived from both lidar measurements using a value for the aerosol extinction/backscattering ratio S(sub a) = 60 sr for the aerosol extinction/backscattering ratio, which was determined from the Raman lidar measurements. The lidar measurements of AOT are found to be generally within 25% of the AOT measured by the NASA Ames Airborne Tracking Sun Photometer (AATS-6). However, during certain periods the lidar and Sun photometer measurements of AOT differed significantly, possibly because of variations in the aerosol physical characteristics (e.g., size, composition) which affect S(sub a). Estimates of PWV, derived from water vapor mixing ratio profiles measured by LASE, are within 5-10% of PWV derived from the airborne Sun photometer. Aerosol extinction profiles measured by both lidars show that aerosols were generally concentrated in the lowest 2-3 km.

Ferrare, R.; Ismail, S.; Browell, E.; Brackett, V.; Clayton, M.; Kooi, S.; Melfi, S. H.; Whiteman, D.; Schwemmer, G.; Evans, K.

2000-01-01

91

Evaluation of a Raman Lidar for Atmospheric Water Vapour Profiling  

Microsoft Academic Search

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

G. J. Kunz; G. deLeeuw

2002-01-01

92

Characterization of fresh and aged biomass burning events using multiwavelength Raman lidar and mass spectrometry  

NASA Astrophysics Data System (ADS)

This paper focuses on optical and microphysical properties of long-range transported biomass burning (BB) aerosols and their variation with atmospheric evolution (ageing), as observed by a multiwavelength Raman lidar, part of EARLINET (European Aerosol LIdar NETwork). Chemical analysis of the atmospheric aerosol was done using a colocated aerosol mass spectrometer (AMS). One relevant optical parameter for the ageing process is the Ångström exponent. In our study, we find that it decreases from 2 for fresh to 1.4-0.5 for aged smoke particles. The ratio of lidar (extinction-to-backscatter) ratios (LR532/LR355) changes rapidly from values <1 for fresh to >1 for aged particles. The imaginary part of the refractive index is the most sensitive microphysical parameter. It decreases sharply from 0.05 to less than 0.01 for fresh and aged smoke particles, respectively. Single-scattering albedo (SSA) varies from 0.74 to 0.98 depending on aerosol age and source. The AMS was used to measure the marker ions of wood-burning particles during 2 days of measurements when the meteorological conditions favored the downward mixing of aerosols from lofted layers. Particle size distribution and particle effective radius from both AMS and lidar are similar, i.e., particle effective radii were approximately 0.27 µm for fresh BB aerosol particles. Microphysical aerosol properties from inversion of the lidar data agree with similar studies carried out in different regions on the globe. Our study shows that the Ångström exponent LR532/LR355 and the imaginary part of the refractive index can be used to clearly distinguish between fresh and aged smoke particles.

Nicolae, D.; Nemuc, A.; Müller, D.; Talianu, C.; Vasilescu, J.; Belegante, L.; Kolgotin, A.

2013-04-01

93

Identification of aerosol composition from multi-wavelength lidar measurements  

NASA Technical Reports Server (NTRS)

This paper seeks to develop the potential of lidar for the identification of the chemical composition of atmospheric aerosols. Available numerical computations suggest that aerosols can be identified by the wavelength dependence of aerosol optical properties. Since lidar can derive the volume backscatter coefficient as a function of wavelength, a multi-wavelength lidar system may be able to provide valuable information on the composition of aerosols. This research theoretically investigates the volume backscatter coefficients for the aerosol classes, sea-salts, and sulfates, as a function of wavelength. The results show that these aerosol compositions can be characterized and identified by their backscatter wavelength dependence. A method to utilize multi-wavelength lidar measurements to discriminate between compositionally different thin aerosol layers is discussed.

Wood, S. A.

1984-01-01

94

Airborne and Ground-Based Measurements Using a High-Performance Raman Lidar  

NASA Technical Reports Server (NTRS)

A high-performance Raman lidar operating in the UV portion of the spectrum has been used to acquire, for the first time using a single lidar, simultaneous airborne profiles of the water vapor mixing ratio, aerosol backscatter, aerosol extinction, aerosol depolarization and research mode measurements of cloud liquid water, cloud droplet radius, and number density. The Raman Airborne Spectroscopic Lidar (RASL) system was installed in a Beechcraft King Air B200 aircraft and was flown over the mid-Atlantic United States during July August 2007 at altitudes ranging between 5 and 8 km. During these flights, despite suboptimal laser performance and subaperture use of the telescope, all RASL measurement expectations were met, except that of aerosol extinction. Following the Water Vapor Validation Experiment Satellite/Sondes (WAVES_2007) field campaign in the summer of 2007, RASL was installed in a mobile trailer for groundbased use during the Measurements of Humidity and Validation Experiment (MOHAVE-II) field campaign held during October 2007 at the Jet Propulsion Laboratory s Table Mountain Facility in southern California. This ground-based configuration of the lidar hardware is called Atmospheric Lidar for Validation, Interagency Collaboration and Education (ALVICE). During theMOHAVE-II field campaign, during which only nighttime measurements were made, ALVICE demonstrated significant sensitivity to lower-stratospheric water vapor. Numerical simulation and comparisons with a cryogenic frost-point hygrometer are used to demonstrate that a system with the performance characteristics of RASL ALVICE should indeed be able to quantify water vapor well into the lower stratosphere with extended averaging from an elevated location like Table Mountain. The same design considerations that optimize Raman lidar for airborne use on a small research aircraft are, therefore, shown to yield significant dividends in the quantification of lower-stratospheric water vapor. The MOHAVE-II measurements, along with numerical simulation, were used to determine that the likely reason for the suboptimal airborne aerosol extinction performance during theWAVES_2007 campaign was amisaligned interference filter. With full laser power and a properly tuned interference filter,RASL is shown to be capable ofmeasuring themain water vapor and aerosol parameters with temporal resolutions of between 2 and 45 s and spatial resolutions ranging from 30 to 330 m from a flight altitude of 8 km with precision of generally less than 10%, providing performance that is competitive with some airborne Differential Absorption Lidar (DIAL) water vapor and High Spectral Resolution Lidar (HSRL) aerosol instruments. The use of diode-pumped laser technology would improve the performance of an airborne Raman lidar and permit additional instrumentation to be carried on board a small research aircraft. The combined airborne and ground-based measurements presented here demonstrate a level of versatility in Raman lidar that may be impossible to duplicate with any other single lidar technique.

Whiteman, David N.; Rush, Kurt; Rabenhorst, Scott; Welch, Wayne; Cadirola, Martin; McIntire, Gerry; Russo, Felicita; Adam, Mariana; Venable, Demetrius; Connell, Rasheen; Veselovskii, Igor; Forno, Ricardo; Mielke, Bernd; Stein, Bernhard; Leblanc, Thierry; McDermid, Stuart; Voemel, Holger

2010-01-01

95

Comparison of Aerosol Optical Properties and Water Vapor Among Ground and Airborne Lidars and Sun Photometers During TARFOX  

NASA Technical Reports Server (NTRS)

We compare aerosol optical thickness (AOT) and precipitable water vapor (PWV) measurements derived from ground and airborne lidars and Sun photometers during TARFOX (Tropospheric Aerosol Radiative Forcing Observational Experiment). Such comparisons are important to verify the consistency between various remote sensing measurements before employing them in any assessment of the impact of aerosols on the global radiation balance. Total scattering ratio and extinction profiles measured by the ground-based NASA/GSFC Scanning Raman Lidar (SRL) system, which operated from Wallops Island, Virginia (37.86 deg N, 75.51 deg W), are compared with those measured by the Lidar Atmospheric Sensing Experiment (LASE) airborne lidar system aboard the NASA ER-2 aircraft. Bias and rms differences indicate that these measurements generally agreed within about 10%. Aerosol extinction profiles and estimates of AOT are derived from both lidar measurements using a value for the aerosol extinction/backscattering ratio S(sub a)=60 sr for the aerosol extinction/backscattering ratio, which was determined from the Raman lidar measurements.

Ferrare, R.; Ismail, S.; Browell, E.; Brackett, V.; Clayton, M.; Kooi, S.; Melfi, S. H.; Whiteman, D.; Schwemmer, G.; Evans, K.; Russell, P.; Livingston, J.; Schmid, B.; Holben, B.; Remer, L.; Smirnov, A.; Hobbs, P. V.

2000-01-01

96

Aerosol Measurements by the Globally Distributed Micro Pulse Lidar Network  

NASA Technical Reports Server (NTRS)

Full time measurements of the vertical distribution of aerosol are now being acquired at a number of globally distributed MP (micro pulse) lidar sites. The MP lidar systems provide full time profiling of all significant cloud and aerosol to the limit of signal attenuation from compact, eye safe instruments. There are currently eight sites in operation and over a dozen planned. At all sited there are also passive aerosol and radiation measurements supporting the lidar data. Four of the installations are at Atmospheric Radiation Measurement program sites. The network operation includes instrument operation and calibration and the processing of aerosol measurements with standard retrievals and data products from the network sites. Data products include optical thickness and extinction cross section profiles. Application of data is to supplement satellite aerosol measurements and to provide a climatology of the height distribution of aerosol. The height distribution of aerosol is important for aerosol transport and the direct scattering and absorption of shortwave radiation in the atmosphere. Current satellite and other data already provide a great amount of information on aerosol distribution, but no passive technique can adequately resolve the height profile of aerosol. The Geoscience Laser Altimeter System (GLAS) is an orbital lidar to be launched in early 2002. GLAS will provide global measurements of the height distribution of aerosol. The MP lidar network will provide ground truth and analysis support for GLAS and other NASA Earth Observing System data. The instruments, sites, calibration procedures and standard data product algorithms for the MPL network will be described.

Spinhirne, James; Welton, Judd; Campbell, James; Berkoff, Tim; Starr, David (Technical Monitor)

2001-01-01

97

SAM II and lidar aerosol profile comparisons during AASE  

NASA Technical Reports Server (NTRS)

The NASA Langley Research Center aerosol lidar system was one of several instruments that flew aboard a DC-8 during the Airborne Arctic Stratospheric Expedition. Several of the Stratospheric Aerosol Measurement II (SAM II) altitude profiles of aerosol extinction were close enough in time and space to allow for intercomparison with the lidar measurements of aerosol backscatter. Comparisons between three SAM II 1.0 micron aerosol extinction profiles and analogous profiles inferred from nearly simultaneous airborne lidar measurements are discussed. The other two comparisons show the first near-simultaneous SAM II/lidar measurements of a polar stratospheric cloud (PSC). The comparison made well within the edge of a relatively homogeneous PSC layer was also good, especially using an extinction-to-backscatter model derived from in situ PSC particle size measurements.

Osborn, M. T.; Poole, L. R.; Wang, Pi-Huan

1990-01-01

98

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

99

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

100

Airborne DIAL and ground-based Raman lidar measurements of water vapor over the Southern Great Plains  

NASA Astrophysics Data System (ADS)

Measurements of water vapor profiles over the Southern Great Plains acquired by two different lidars are presented. NASA's airborne DIAL Lidar Atmospheric Sensing Experiment (LASE) system measured water vapor, aerosol, and cloud profiles during the ARM/FIRE Water Vapor Experiment (AFWEX) in November-December 2000 and during the International H2O Project (IHOP) in May-June 2002. LASE measurements acquired during AFWEX are used to characterize upper troposphere water vapor measured by ground-based Raman lidars, radiosondes, and in situ aircraft sensors. LASE measurements acquired during IHOP are being used to better understand the influence water vapor variability on the initiation of deep convection and to improve the quantification and prediction of precipitation associated with these storms. The automated Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) Cloud and Radiation Testbed (CART) Raman Lidar (CARL) has been routinely measuring profiles of water vapor mixing ratio, relative humidity, aerosol extinction, aerosol backscattering, and aerosol and cloud depolarization during both daytime and nighttime operations. Aerosol and water vapor profiles acquired since March 1998 are used to investigate the seasonal variability of the vertical distributions of water vapor and aerosols.

Ferrare, Richard A.; Browell, Edward V.; Ismail, Syed; Kooi, Susan; Brackett, Vince G.; Clayton, Marian; Notari, Anthony; Butler, Carolyn F.; Barrick, John; Diskin, Glenn; Lesht, Barry; Schmidlin, Frank J.; Turner, Dave; Whiteman, David; Miloshevich, Larry

2003-12-01

101

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

102

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

103

Long Term Stratospheric Aerosol Lidar Measurements in Kyushu.  

National Technical Information Service (NTIS)

Lidar soundings of the stratospheric aerosols have been made since 1972 at Fukuoka, Kyushu Island of Japan. Volcanic clouds from eruptions of La Soufriere, Sierra Negra, St. Helens, Uluwan, Alaid, unknown volcano, and El Chichon were detected one after an...

M. Fujiwara

1992-01-01

104

Characterization of the aerosol type using simultaneous measurements of the lidar ratio and estimations of the single scattering albedo  

NASA Astrophysics Data System (ADS)

Lidar measurements of the vertical distribution of the aerosol extinction and backscatter coefficient and the corresponding extinction to backscatter ratio (so-called lidar ratio) at 355 nm have been performed at Thessaloniki, Greece using a Raman lidar system in the frame of the EARLINET for the period 2001-2005. Coincident spectral UV irradiance measurements, total ozone observations and aerosol optical depth estimates were available from a double Brewer spectroradiometer. The retrieval of single scattering albedo employed the Brewer global irradiance measurements and radiative transfer modeling. Vertically averaged values of the lidar ratio ranged from a minimum of 16 sr to a maximum value of 90 sr, while the effective single scattering albedo ranged from 0.78 to 1.00. The mean value of the lidar ratio for the dataset under study was 45.5 ± 21.0 sr while the average value of the single scattering albedo was 0.94 ± 0.05. For the majority of our measurements (80%) the single scattering albedo found to be greater than 0.90. Using additional information from backward trajectory calculations and lidar-derived free tropospheric contribution of aerosols in the columnar aerosol optical depth, it is shown that the combined use of the directly measured lidar ratio, and the indirectly estimated single scattering albedo, leads to a better characterization of the aerosol type probed.

Amiridis, Vassilis; Balis, Dimitrios; Giannakaki, Eleni; Kazadzis, Stylianos; Arola, Antti; Gerasopoulos, Evangelos

2011-07-01

105

Improvement on lidar data processing for stratospheric aerosol measurements  

Microsoft Academic Search

For lidar measurements of stratospheric aerosols; signal-induced noise (SIN) from a photomultiplier (PMT) has been a problem of particular interest. In this paper, lidar signals affected by the PMT are simulated after a long tail with a decay time of about 200 microsec is found in the PMT's response to an impulse-like light exposure. Computer simulation quantitatively revealed that the

Yoshikazu Iikura; Nobuo Sugimoto; Yasuhiro Sasano; Hiroshi Shimzu

1987-01-01

106

Aerosol Lidar and MODIS Satellite Comparisons for Future Aerosol Loading Forecast  

NASA Technical Reports Server (NTRS)

Knowledge of the concentration and distribution of atmospheric aerosols using both airborne lidar and satellite instruments is a field of active research. An aircraft based aerosol lidar has been used to study the distribution of atmospheric aerosols in the California Central Valley and eastern US coast. Concurrently, satellite aerosol retrievals, from the MODIS (Moderate Resolution Imaging Spectroradiometer) instrument aboard the Terra and Aqua satellites, were take over the Central Valley. The MODIS Level 2 aerosol data product provides retrieved ambient aerosol optical properties (e.g., optical depth (AOD) and size distribution) globally over ocean and land at a spatial resolution of 10 km. The Central Valley topography was overlaid with MODIS AOD (5x5 sq km resolution) and the aerosol scattering vertical profiles from a lidar flight. Backward air parcel trajectories for the lidar data show that air from the Pacific and northern part of the Central Valley converge confining the aerosols to the lower valley region and below the mixed layer. Below an altitude of 1 km, the lidar aerosol and MODIS AOD exhibit good agreement. Both data sets indicate a high presence of aerosols near Bakersfield and the Tehachapi Mountains. These and other results to be presented indicate that the majority of the aerosols are below the mixed layer such that the MODIS AOD should correspond well with surface measurements. Lidar measurements will help interpret satellite AOD retrievals so that one day they can be used on a routine basis for prediction of boundary layer aerosol pollution events.

DeYoung, Russell; Szykman, James; Severance, Kurt; Chu, D. Allen; Rosen, Rebecca; Al-Saadi, Jassim

2006-01-01

107

Aerosol lidar and MODIS satellite comparisons for future aerosol loading forecast  

NASA Astrophysics Data System (ADS)

Knowledge of the concentration and distribution of atmospheric aerosols using both airborne lidar and satellite instruments is a field of active research. An aircraft based aerosol lidar has been used to study the distribution of atmospheric aerosols in the California Central Valley and eastern US coast. Concurrently, satellite aerosol retrievals, from the MODIS (Moderate Resolution Imaging Spectroradiometer) instrument aboard the Terra and Aqua satellites, were take over the Central Valley. The MODIS Level 2 aerosol data product provides retrieved ambient aerosol optical properties (e.g., optical depth (AOD) and size distribution) globally over ocean and land at a spatial resolution of 10 km. The Central Valley topography was overlaid with MODIS AOD (5x5 km2 resolution) and the aerosol scattering vertical profiles from a lidar flight. Backward air parcel trajectories for the lidar data show that air from the Pacific and northern part of the Central Valley converge confining the aerosols to the lower valley region and below the mixed layer. Below an altitude of 1 km, the lidar aerosol and MODIS AOD exhibit good agreement. Both data sets indicate a high presence of aerosols near Bakersfield and the Tehachapi Mountains. These and other results to be presented indicate that the majority of the aerosols are below the mixed layer such that the MODIS AOD should correspond well with surface measurements. Lidar measurements will help interpret satellite AOD retrievals so that one day they can be used on a routine basis for prediction of boundary layer aerosol pollution events.

De Young, Russell; Szykman, James; Severance, Kurt; Chu, D. Allen; Rosen, Rebecca; Al-Saadi, Jassim

2006-09-01

108

Automatic gain control for Raman lidar signals  

Microsoft Academic Search

Electronic component improvements allow everyone to use them for performing new features in different applications. Lidar signal control is matter of continuous design and it can be studied in order to increase signal-to-noise ratio. Fortunately, the advent, of programmable gain amplifiers, switching capacitor filters and specific AD converters, is the stimulus of improving lidar signal quality. The main scope of

Aimé Lay-Ekuakille; Giuseppe Vendramin; Amerigo Trotta

2008-01-01

109

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

110

Tropospheric temperature measurements using a rotational raman lidar  

NASA Astrophysics Data System (ADS)

Using the Hampton University (HU) Mie and Raman lidar, tropospheric temperature profiles were inferred from lidar measurements of anti-Stokes rotational Raman (RR) backscattered laser light from atmospheric nitrogen and oxygen molecules. The molecules were excited by 354.7 nanometer (nm) laser light emitted by the HU lidar. Averaged over 60-minute intervals, RR backscattered signals were detected in narrow 353.35 nm and 354.20 nm spectral bands with full-widths-at-half-maxima (FWHM) of 0.3 nm. During the special April 19-30, 2012, Ground-Based Remote Atmospheric Sounding Program (GRASP) campaign, the lidar temperature calibration coefficients were empirically derived using linear least squares and second order polynomial analyses of the lidar backscattered RR signals and of reference temperature profiles, obtained from radiosondes. The GRASP radiosondes were launched within 400 meters of the HU lidar site. Lidar derived temperature profiles were obtained at altitudes from the surface to over 18 kilometers (km) at night, and up to 5 km during the day. Using coefficients generated from least squares analyses, nighttime profiles were found to agree with profiles from reference radiosonde measurements within 3 K, at altitudes between 4 km and 9 km. Coefficients generated from the second order analyses yielded profiles which agreed with the reference profiles within 1 K uncertainty level in the 4 km to 10 km altitude region. Using profiles from GRASP radiosondes, the spatial and temporal homogeneities of the atmosphere, over HU, were estimated at the 1.5 K level within a 10 km radius of HU, and for observational periods approaching 3 hours. Theoretical calibration coefficients were derived from the optical and physical properties of the HU RR lidar and from the spectroscopic properties of atmospheric molecular nitrogen and oxygen. The theoretical coefficients along with lidar measurements of sky background radiances were used to evaluate the temporal stability of the empirically derived temperature profiles from the RR lidar measurements. The evaluations revealed systematic drifts in the coefficients. Frequent reference radiosonde temperature profiles should be used to correct for the drifts in the coefficients. For the first time, the cause of the coefficient drifts has been identified as the differences in the aging of the spectral responses of the HU lidar detector pairs. For the first time, the use of lidar sky background measurements was demonstrated as a useful technique to correct for the coefficient drift. This research should advance the derivations of lidar temperature calibration coefficients which can be used for long observational periods of temperature fields without the need for frequent lidar calibrations using radiosondes.

Lee, Robert Benjamin, III

111

Airborne High Spectral Resolution Lidar Measurements of Atmospheric Aerosols  

NASA Astrophysics Data System (ADS)

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 and extinction profiles at 532 nm and the standard backscatter lidar technique to measure aerosol backscatter profiles at 1064 nm. Depolarization profiles are measured at both wavelengths. Since March 2006, the airborne HSRL has acquired over 215 flight hours of data deployed on the NASA King Air B200 aircraft during several field experiments. Most of the flights were conducted during two major field experiments. The first major experiment was 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 that was conducted during March 2006 to investigate the evolution and transport of pollution from Mexico City. The second major experiment was the Texas Air Quality Study (TEXAQS)/Gulf of Mexico Atmospheric Composition and Climate Study (GoMACCS) that was conducted during August and September 2006 to investigate climate and air quality in the Houston/Gulf of Mexico region. Several flights were also conducted to help validate the Cloud-Aerosol LIdar with Orthogonal Polarization (CALIOP) lidar on board the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite (CALIPSO) satellite. In February 2007, several flights were carried out as part of an Environmental Protection Agency (EPA) experiment to assess air quality in central California. Airborne HSRL data acquired during these missions were used to quantify aerosol extinction and optical thickness contributed by various aerosol types. Several B200 flights conducted during MILAGRO were coordinated with flights carried out by the Department of Energy G-1 aircraft, the National Center for Atmospheric Research (NCAR) C-130 aircraft, and/or the Sky Research J-31 aircraft. In situ measurements of aerosol microphysical properties acquired on G-1 and C-130 are being used to investigate the ability to discern various aerosol types using the HSRL data. Aerosol extinction profiles derived from the in situ measurements and from the NASA Ames Airborne Tracking Sun Photometer on board the J-31 are being used to assess the HSRL aerosol extinction profiles. Additional applications of airborne HSRL data to be discussed include: 1) characterization of the spatial and vertical distributions of aerosols, 2) investigation of aerosol variability near clouds, 3) evaluation of model simulations of aerosol transport, and 4) assessments of aerosol optical properties derived from a combination of surface, airborne, and satellite measurements.

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

2007-05-01

112

The application of lidar to stratospheric aerosol studies  

NASA Technical Reports Server (NTRS)

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

Mccormick, M. P.

1986-01-01

113

Measurements of upper tropospheric moisture with a Raman lidar.  

National Technical Information Service (NTIS)

We describe water vapor profile measurements made with the Sandia Raman lidar. The goal of this study is to determine the effect of convection on the upper tropospheric moisture budget. At present, considerable controversy exists over the nature of the ve...

S. E. Bisson J. E. M. Goldsmith A. D. Del Genio

1994-01-01

114

Aerosol particle analysis by Raman scattering technique  

SciTech Connect

Laser Raman spectroscopy is a very versatile tool for chemical characterization of micron-sized particles. Such particles are abundant in nature, and in numerous energy-related processes. In order to elucidate the formation mechanisms and understand the subsequent chemical transformation under a variety of reaction conditions, it is imperative to develop analytical measurement techniques for in situ monitoring of these suspended particles. In this report, we outline our recent work on spontaneous Raman, resonance Raman and non-linear Raman scattering as a novel technique for chemical analysis of aerosol particles as well as supersaturated solution droplets.

Fung, K.H.; Tang, I.N.

1992-10-01

115

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

NASA Technical Reports Server (NTRS)

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

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

1998-01-01

116

High-resolution Raman lidar for simultaneous measurement of temperature and water vapor in the lower atmosphere at a coastal station, Trivandrum  

NASA Astrophysics Data System (ADS)

This work reports the development and preliminary results of the Vibrational Raman lidar at a coastal station, Trivandrum (8°33'N, 77°E). A Raman lidar technique for measuring atmospheric temperature and water vapor using vibrational Raman spectra of N2 and H IIO are discussed in detail. Interference filters at 607 and 660nm of 1nm band- width are used in the Raman lidar channel. Nighttime temperature and water vapor profiles are obtained from 1-5km in the lower atmosphere. Lidar water vapor profiles are in good agreement with the Regional Model data. The variation in the temperature profiles may be due to the indirect aerosol effect in the lower atmosphere.

Satyanarayana, M.; Radhakrishnan, S. R.; Presennakumar, B.; Murty, V. S.; Bindhu, R.

2006-12-01

117

Long range transport of Asian dust and dust-cloud interaction observed by Raman lidar and CALIPSO measurements  

NASA Astrophysics Data System (ADS)

Interactions of dust aerosols with clouds and pollution are important issues for climate and environment. In this study, we investigated dust properties by using Mie/Raman/Polarization lidar systems at wavelengths 532/355/386/407 nm at Chung-Li (24.6N, 121.1E) and compared our studies with CALIPSO measurements. The occurrence of a dust event on March 14, 2009 in Chungli was clearly observed by ground and space lidar systems. CALIPSO observed the occurrence of dust originated in the Northwest China and transported to the south reaching Taiwan three days later. Our observations involve measuring backscattering, polarization, and Raman scatterings of aerosols and water vapor. By comparing the polarization measurements at 532 nm with Raman measurements at 355/386/407 nm, we can clearly see the modification of dust particles because of interaction with cloud, the later was observed in Raman lidar. Reducing of the depolarization ratio due to changing particle shapes and sizes is observed in polarization lidar measurements. CALIPSO data shows properties of the dust along the path of transport.

Huang, Z.; Nee, J. B.

2012-12-01

118

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

119

Analysis and interpretation of lidar observations of the stratospheric aerosol  

NASA Technical Reports Server (NTRS)

Data obtained with a 48 in. telescope lidar system are compared with results obtained using a one-dimensional stratospheric aerosol model to analyze various microphysical processes influencing the formation of this aerosol. Special attention is given to the following problems: (1) how lidar data can help determine the composition of the aerosol particles and (2) how the layer corresponds to temperature profile variations. The lidar record during the period 1974 to 1979 shows a considerable decrease of the peak value of the backscatter ratio. Seasonal variations in the aerosol layer and a gradual decrease in stratospheric loading are observed. The aerosol model simulates a background stratospheric aerosol layer, and it predicts stratospheric aerosol concentrations and compositions. Numerical experiments are carried out by using the model and by comparing the theoretical results with the experimentally obtained lidar record. Comparisons show that the backscatter profile is consistent with the composition when the particles are sulfuric acid and water; it is not consistent with an ammonium sulfate composition. It is shown that the backscatter ratio is not sensitive to the composition or stratospheric loading of condensation nuclei such as meteoritic debris.

Hamill, P.; Swissler, T. J.; Osborn, M.; Mccormick, M. P.

1980-01-01

120

Multiple-wavelength Raman lidar measurements of atmospheric water vapor  

SciTech Connect

Height profiles of atmospheric water vapor obtained using a multiple-wavelength Raman lidar are examined. The water vapor profiles exhibit vertical structure with scales on the order of the resolution of the lidar (75 m). To determine whether such structure is atmospheric in origin, measurements obtained simultaneously in a common volume at two independent wavelengths were compared. Correlation of the gradients of the water vapor profiles obtained from these two wavelengths yielded an average correlation factor of 0.88. It was also observed that for the given meteorological conditions, the vertical structure decorrelated with a time constant of approximately three hours. 7 refs., 4 figs., 1 tab.

Rajan, S.; Kane, T.J.; Philbrick, C.R. [Pennsylvania State Univ., University Park, PA (United States)] [Pennsylvania State Univ., University Park, PA (United States)

1994-11-15

121

Modular and mobile multipurpose lidar system for observation of tropospheric and stratospheric aerosols  

NASA Astrophysics Data System (ADS)

An aerosol Raman lidar with a frequency doubled and tripled Nd:YAG laser and a 1140 mm diameter receiving telescope is under development for measurements of aerosol backscatter, extinction coefficients and depolarization in the altitude range 5 to 50 km. The light received by the telescope is split according to polarization and fed via glass fibers to a filter polychromator and to photon-counting detectors. The lidar is mounted on a removable carrier inside an air-conditioned 20 ft standard container and can be operated anywhere in the world, even at sea and under extreme climatic conditions (Antarctica, Tropics). Tests are carried out during a 1996 cruise of the German research vessel Polarstern from Europe to Antarctica.

Schafer, Juergen; Schrems, Otto; Beyerle, Georg; Hofer, Bernd; Mildner, Wolfgang; Theopold, Felix A.; Lahmann, Wilhelm; Weitkamp, Claus; Steinbach, Manfred

1995-12-01

122

Ship wake detection by Raman lidar.  

PubMed

We carried out a remote study of ship wakes by optical methods. Both Mie and Raman scattering signals and their evolution were simultaneously recorded by gated detector (intensified CCD). The Mie scattering signal was detectable within 1?min after water disturbance by a high-speed boat. According to an approximation of experimental data, Raman signal fluctuations can be detected for a much longer time under the same conditions. We have demonstrated that Raman spectroscopy is substantially more sensitive to water perturbation compared to conventional acoustic (sonar) technique and can be used for ship wake detection and monitoring. PMID:21283224

Bunkin, Alexey F; Klinkov, Vladimir K; Lukyanchenko, Vladislav A; Pershin, Sergey M

2011-02-01

123

Transport processes as manifested in satellite and lidar aerosol measurements  

NASA Technical Reports Server (NTRS)

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.

1985-01-01

124

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

125

Detection of volcanic ash from the Eyjafjallajoekull eruption with a Raman lidar over Thessaloniki Greece  

NASA Astrophysics Data System (ADS)

The arrival of the volcanic ash plume of the Eyjafjallajökull eruption was observed over Greece almost one week after its major eruption (on April 14, 2010) with a Raman lidar system. Intensive lidar measurements were performed throughout the event in Thessaloniki to derive the optical properties of the ash aerosols in the troposphere. During April 21, 2010 two layers of volcanic ash were present over Thessaloniki, one around 2.5 and one around 5 km height after circulating over central Europe. The first layer was persistent but with variable thickness, while the thin layer observed at 5 km height disappeared after some hours. Later on and at higher altitudes thin layers of ash were observed between 5 and 8 km, directly associated with the volcanic eruption. The observed layer at around and 3 km was persistently observed till April 28.

Giannakaki, Elina; Balis, Dimitris; Bais, Alkiviadis

2010-05-01

126

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

NASA Astrophysics Data System (ADS)

A permanent UV Raman Lidar station, designed to perform continuous measurements of aerosols and water vapor and aiming to study and monitor the atmosphere on the weather to climatic time scales, became operational in central Amazon in July 2011. The automated data acquisition and internet monitoring enabled extended hours of daily measurements when compared to a manually operated instrument. This paper gives a technical description of the system, presents its experimental characterization and the algorithms used for obtaining the aerosol optical properties and identifying the cloud layers. Data from one week of measurements during the dry season of 2011 were analyzed as a mean to assess the overall system capability and performance. A comparison of the aerosol optical depth from the Lidar and a co-located AERONET sun photometer showed a root mean square error of about 0.06, small compared to the range of observed AOD values (0.1 to 0.75) and to the typical AERONET AOD uncertainty (0.02). By combining nighttime measurements of the aerosol lidar ratio (50-65 sr), backtrajectories calculations and fire spots observed from satellites we showed that observed particles originated from biomass burning. Cirrus clouds were observed in 60% of our measurements. Most of the time they were distributed into three layers between 11.5 and 13.4 km a.g.l. The systematic and long-term measurements being made by this new scientific facility have the potential to significantly improve our understanding of the climatic implications of the anthropogenic changes in aerosol concentrations over the pristine Amazônia.

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

2014-01-01

127

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

Microsoft Academic Search

The Canadian Network for the Detection of Atmospheric Change (CANDAC) Rayleigh-Mie-Raman Lidar (CRL) was installed in the Canadian High Arctic at Eureka, Nunavut (80°N, 86°W) in 2008-2009. The remotely-operated system began with measurement capabilities for multi-wavelength aerosol extinction, water vapour mixing ratio, and tropospheric temperature profiles, as well as particulate density and colour ratio. In 2010, a new depolarisation channel

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

2010-01-01

128

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

SciTech Connect

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

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

2006-04-10

129

Lidar data assimilation for improved analyses of volcanic aerosol events  

NASA Astrophysics Data System (ADS)

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

Lange, Anne Caroline; Elbern, Hendrik

2014-05-01

130

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

131

Verification measurement of a polarization Raman elastic-backscatter lidar  

NASA Technical Reports Server (NTRS)

By measuring the depolarization of light Raman scattered from a gas of known number density (nitrogen), it is possible to determine the influence of multiple scattering on lidar signals. In order to realize such measurements, linearly polarized laser light is emitted and two components of the nitrogen Raman signals, with E vectors parallel (parallel P sub lambda R) and perpendicular (perpendicular P sub lambda R) to the plane of polarization of the laser light, are measured. The depolarization ratio, delta sub lambda R = perpendicular P sub lambda R/parallel P sub lambda R, is constant if only the Raman scattering process contributes to the signal. Any variation of the depolarization is caused by additional elastic, and, thus, multiple scattering. If the contribution of multiple scattered light to the lidar signals is known, other parameters determined with the systems such as extinction, backscattering, and the depolarization of elastically scattered light, can be corrected for this influence. The lidar system used for the polarization measurements, especially the receiver setup, is described. The calibration of the apparatus and a clear air measurement are discussed.

Schulze, Christoph; Wandinger, Ulla; Ansmann, Albert; Weitkamp, Claus; Michaelis, Walfried

1992-01-01

132

Lidar measurement of stratospheric aerosol at Syowa Station, Antarctica  

NASA Technical Reports Server (NTRS)

Lidar measurement on Antarctic aerosols were made during the Antarctic Middle Atmosphere (AMA) period, 1983 to 1985, at Syowa Station. Topics measured are winter enhancement aerosol layer and volcanic effect of El Chichon on the Antarctic stratosphere aerosols. The large depolarization ratio (maximum value was about 0.8) seems to support sublimation growth of ice crystals. The lidar measurements showed a meaningful time lag between aerosol content increase and depolarization ratio increase. Considering the balloon observations made in early winter, it was speculated that an increase in large particle number concentration also contributed to the winter enhancement. The El Chichon cloud spread to the Antarctic region by the beginning of 1983. The temporal change of integrated backscatter coefficient shows a clear decay pattern, although strong winter enhancement superposes.

Iwasaka, Y.; Hirasawa, T.; Fukunishi, H.; Ono, T.; Nomura, A.

1986-01-01

133

Aerosol Models for the CALIPSO Lidar Inversion Algorithms  

NASA Technical Reports Server (NTRS)

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 105 records of radiance measurements, aerosol size distributions, and complex refractive indices to generate the optical properties of the aerosol at more 200 sites worldwide. These properties together with the radiance measurements are then classified using classical clustering methods to group the sites according to the type of aerosol with the greatest frequency of occurrence at each site. Six significant clusters are identified: desert dust, biomass burning, urban industrial pollution, rural background, marine, and dirty pollution. Three of these are used in the CALIPSO aerosol models to characterize desert dust, biomass burning, and polluted continental aerosols. The CALIPSO aerosol model also uses the coarse mode of desert dust and the fine mode of biomass burning to build a polluted dust model. For marine aerosol, the CALIPSO aerosol model uses measurements from the SEAS experiment 3. In addition to categorizing the aerosol types, the cluster analysis provides all the column optical and microphysical properties for each cluster.

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

2003-01-01

134

Aerosol Scavenging by Cirrus Clouds: Evidence from Polarization Lidar Measurements  

NASA Astrophysics Data System (ADS)

Under some conditions polarization lidar observations of ice clouds suggest the depletion of aerosol particles in the vicinity of the cloud margins and just below cloud base. This is particularly evident for cirrus that form in connection with transported desert dust layers, because these dust particles can be relatively large and hence strongly backscattering and depolarizing. Indications of aerosol scavenging primarily through the ice nucleation and gravitational capture processes, as well as phoretic forces where ice crystals are evaporating, can then produce a noticeable decrease in lidar backscattering and depolarization in clear (but recently cloudy) air. (In contrast, aerosol loss due to Brownian diffusion may not be as noticeable because these generally smaller particles are relatively weak backscatterers.) Presumably, previously cloudy air with its depleted interstitial aerosol is disclosed by variable fallstreak production and evaporation effects. The action of clouds is of great importance to the redistribution and removal (through precipitation) of aerosols suspended in the atmosphere. Polarization lidar examples will be given of aerosol-depleted halos surrounding cirrus cloud elements and backscatter troughs just below the base of undulating cirrus layers.

Sassen, K.; Zhu, J.

2007-12-01

135

Measurement of Multiple Scattering Effects with a Polarization Raman Elastic-Backscatter Lidar.  

National Technical Information Service (NTIS)

A new method for the determination of multiple scattering effects is described. A polarization Raman elastic backscatter lidar is used, which allows the measurement of the depolarization of both the elastically backscattered light and the light Raman scat...

U. Wandinger A. Ansmann C. Weitkamp W. Michaelis

1992-01-01

136

Evaluation of the Navy Oceanic Vertical Aerosol Model Using Lidar and PMS Particle-Size Spectrometers.  

National Technical Information Service (NTIS)

The Navy Oceanic Vertical Aerosol Model (NOVAM) was evaluated by making nearly simultaneous measurements of atmospheric structure with an airborne lidar and Particle Measuring Systems, Inc., aerosol spectrometers. Profiles of measured aerosol-size distrib...

D. R. Jensen

1990-01-01

137

A Comparison of Dustsonde and LIDAR Measurements of Stratospheric Aerosols.  

National Technical Information Service (NTIS)

This paper decribes the results and analysis of an experiment to compare the stratospheric aerosol profiles as measured by a ballon-borne in situ particle counter and by the backscattered light from a ground-based laser radar (LIDAR) operating at a wavele...

E. E. Remsberg B. Northam

1975-01-01

138

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

139

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

140

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

141

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

SciTech Connect

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

Becherer, R.J.; Werner, C.

1992-01-01

142

Aerosol particle microstructure dependence of accuracy of cw Doppler lidar estimate of wind velocity  

Microsoft Academic Search

The effect of aerosol microstructure on the estimation error of wind velocity measured by cw CO2 Doppler lidar is analyzed in the paper. Based on the numerical simulation of a lidar return is has been shown that aerosol particles, due to their difference in size, make essentially different contribution to a measured lidar return power that leads to deviation of

Viktor A. Banakh; Igor N. Smalikho; Christian H. Werner

2001-01-01

143

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

NASA Technical Reports Server (NTRS)

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

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

2012-01-01

144

Observation of aerosols and clouds planned with the Mission Demonstration Satellite Lidar (ELISE)  

Microsoft Academic Search

The space lidar which is named Experimental Lidar-In-Space Equipment (ELISE) is being developed by the National Space Development Agency of Japan (NASDA) for the Mission Demonstration Satellite II planned for launch in 2002. The primary purpose of ELISE is to demonstrate the space lidar technology and the feasibility of the Mie scattering lidar observation of clouds and aerosols from space.

N. Sugimoto; Y. Sasano

1999-01-01

145

A comparison of dustsonde and LIDAR measurements of stratospheric aerosols  

NASA Technical Reports Server (NTRS)

This paper describes the results and analysis of an experiment to compare the stratospheric aerosol profiles as measured by a balloon-borne in situ particle counter and by the backscattered light from a ground-based laser radar (LIDAR) operating at a wavelength of 6943 A. The profile comparison agrees within the experimental errors for particles with radii greater than 0.25 micrometer and for altitudes between 15 and 28 kilometers. Following the calibration tests, the LIDAR was used to monitor the stratospheric aerosols at Hampton, Virginia. Enhanced backscatter appeared sporadically in November and December of 1974 over Hampton; scattering ratios averaged over altitude increments of 450 meters range from 1.10 at 20 kilometers in early November to 3.3 at 17 kilometers on December 18. The source of this enhanced backscattering is attributed to the aerosols associated with the eruption of the Fuego volcano in Guatemala in mid-October.

Remsberg, E. E.; Northam, G. B.

1975-01-01

146

Atmospheric aerosol profiling with a bistatic imaging lidar system.  

PubMed

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

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

2007-05-20

147

Vertically resolved aerosol properties by multi wavelengths lidar measurements  

NASA Astrophysics Data System (ADS)

A new approach is introduced to characterize the dependence on altitude of the aerosol fine mode radius (Rf) and of the fine mode contribution (?) to the aerosol optical thickness (AOT) by three-wavelength lidar measurements. The introduced approach is based on the graphical method of Gobbi et al. (2007), which was applied to AERONET spectral extinction observations and relies on the combined analysis of the Ångstrom exponent (å) and its spectral curvature ?å. Lidar measurements at 355, 532 and 1064 nm were used in this study to retrieve the vertical profiles of å and ?å and to determine the dependence on altitude of Rf and ? (532 nm) from the å-?å combined analysis. Lidar measurements were performed at the Mathematics and Physics Department of Universita' del Salento, in south eastern Italy. Aerosol from continental Europe, the Atlantic, northern Africa, and the Mediterranean Sea are often advected over south eastern Italy and as a consequence, mixed advection patterns leading to aerosol properties varying with altitude are dominant. The proposed approach was applied to eleven measurement days to demonstrate its feasibility in different aerosol load conditions. The selected-days were characterized by AOTs spanning the 0.23-0.67, 0.15-0.41, and 0.04-0.25 range at 355, 532, and 1064 nm, respectively. Lidar ratios varied within the 28-80, 30-70, and 30-55 sr range at 355, 532, and 1064 nm, respectively, for the high variability of the aerosol optical and microphysical properties. å(355 nm, 1064 nm) values retrieved from lidar measurements ranged between 0.12 and 2.5 with mean value ±1 standard deviation equal to 1.4 ± 0.5. ?å varied within the -0.10-0.87 range with mean value equal to 0.1 ± 0.4. Rf and ? (532 nm) values spanning the 0.02-0.30 ?m and the 0.30-0.99 range, respectively were associated to the å-?å data points. Rf and ? values showed no dependence on the altitude. 72% of the data points were in the ?å-å space delimited by the ? and Rf curves varying within 0.70-0.95 and 0.15-0.05 ?m, respectively for the dominance of fine mode particles in driving the AOT over south eastern Italy. Volume depolarization vertical profiles retrieved from lidar measurements, aerosol products from AERONET sunphotometer measurements collocated in space and time, the BSC-DREAM model, analytical back trajectories, and satellite images were used to demonstrate the robustness of the proposed method.

Perrone, M. R.; De Tomasi, F.; Gobbi, G. P.

2013-07-01

148

Aerosol analysis techniques and results from micro pulse lidar  

NASA Technical Reports Server (NTRS)

The effect of clouds and aerosol on the atmospheric energy balance is a key global change problem. Full knowledge of aerosol distributions is difficult to obtain by passive sensing alone. Aerosol and cloud retrievals in several important areas can be significantly improved with active remote sensing by lidar. Micro Pulse Lidar (MPL) is an aerosol and cloud profilometer that provides a detailed picture of the vertical structure of boundary layer and elevated dust or smoke plume aerosols. MPL is a compact, fully eyesafe, ground-based, zenith pointing instrument capable of full-time, long-term unattended operation at 523 nm. In October of 1993, MPL began taking full-time measurements for the Atmospheric Radiation Measurement (ARM) program at its Southern Great Plains (SGP) site and has since expanded to ARM sites in the Tropical West Pacific (TWP) and the North Slope of Alaska (NSA). Other MPL's are moving out to some of the 60 world-wide Aerosol Robotic Network (AERONET) sites which are already equipped with automatic sun-sky scanning spectral radiometers providing total column optical depth measurements. Twelve additional MPL's have been purchased by NASA to add to the aerosol and cloud database of the EOS ground validation network. The original MPL vertical resolution was 300 meters but the newer versions have a vertical resolution of 30 meters. These expanding data sets offer a significant new resource for atmospheric radiation analysis. Under the direction of Jim Spinhirne, the MPL analysis team at NASA/GSFC has developed instrument correction and backscatter analysis techniques for ARM to detect cloud boundaries and analyze vertical aerosol structures. A summary of MPL applications is found in Hlavka (1997). With the aid of independent total column optical depth instruments such as the Multifilter Rotating Shadowband Radiometer (MFRSR) at the ARM sites or sun photometers at the AERONET sites, the MPL data can be calibrated, and time-resolved vertical profiles of aerosol optical depth as well as aerosol extinction can be calculated. The techniques used to calibrate the lidar, calculate the aerosol extinction-to-backscatter ratio, and produce profiles of aerosol extinction and aerosol optical depths, will be described. Results using these techniques will be presented for case studies at the ARM site in the Tropical West Pacific and later in the Southern Great Plains.

Hlavka, Dennis L.; Spinhirne, James D.; Campbell, James R.; Reagan, John A.; Powell, Donna

1998-01-01

149

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

NASA Astrophysics Data System (ADS)

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

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

2012-11-01

150

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

151

Improvement on lidar data processing for stratospheric aerosol measurements  

NASA Astrophysics Data System (ADS)

For lidar measurements of stratospheric aerosols; signal-induced noise (SIN) from a photomultiplier (PMT) has been a problem of particular interest. In this paper, lidar signals affected by the PMT are simulated after a long tail with a decay time of about 200 microsec is found in the PMT's response to an impulse-like light exposure. Computer simulation quantitatively revealed that the SIN caused by the delayed response became greater than the real signal at high altitudes. Based on the results of the simulation, a proposal was made to find a practical method for identifying and removing the SIN from the actual lidar signals. In addition, an improved method for the lidar signal calibration was proposed, taking into account the systematic noise component, including background light as well as SIN, in formulating the clean air calibration (the matching method). The validity of the proposed methods was demonstrated by using them both with an actual lidar signal and a simulated lidar signal with SIN.

Iikura, Yoshikazu; Sugimoto, Nobuo; Sasano, Yasuhiro; Shimzu, Hiroshi

1987-12-01

152

Improvement on lidar data processing for stratospheric aerosol measurements.  

PubMed

For lidar measurements of stratospheric aerosols; signal-induced noise (SIN) from a photomultiplier (PMT) has been a problem of particular interest. In this paper, we succeed in simulating lidar signals affected by the PMT, after finding a long tail with a decay time of ~200 micros in the PMT's response to an impulselike light exposure. The PMT studied was an RCA 8852. Computer simulation quantitatively revealed that the SIN caused by the delayed response became greater than the real signal at high altitudes. Based on the results of simulation, a proposal was made to find a practical method for identifying and removing the SIN from the actual lidar signals. In addition, an improved method for the lidar signal calibration was proposed by taking into account the systematic noise component, including background light as well as SIN, in formulating the clean air calibration (the matching method). Validity of the proposed methods was demonstrated by using them both with an actual lidar signal and a simulated lidar signal with SIN. PMID:20523520

Likura, Y; Sugimoto, N; Sasano, Y; Shimzu, H

1987-12-15

153

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

154

Marine Boundary Layer Aerosol Profiling with a Camera Lidar  

NASA Astrophysics Data System (ADS)

Aerosol measurements at a coastal site on the Big Island of Hawaii were made to assess the usefulness of a new aerosol profiling technique called CLidar (camera lidar). A scientific-grade digital camera was used with a wide-angle lens (>100 deg) to image a vertically-pointed laser beam which was 122 meters away. The image was then analyzed for aerosol scatter much in the same way a monostatic lidar signal is analyzed except that the altitude information is determined by the geometry. The technique has sub-meter altitude resolution near the ground and can be directly compared with in-situ instruments. Aerosol profiles can be acquired through the boundary-layer with lower altitude resolution. CLidar aerosol measurements were made on two evenings where coastal breaking waves from about 400 meters away were added to the background marine boundary layer. A NASA/AERONET aerosol phase function, as well as a previously directly-measured phase function, were used to convert the single-angle CLidar scatter into extinction. A large gradient in aerosols with altitude was found for the first 35 meters with a lower gradient up to 200 meters. This was probably the region affected by the breaking waves. This is a useful result in characterizing the sampling environment. Nephelometers with intakes at 7 and 25 meters were directly compared with the CLidar results. Agreement was better with the directly-measured phase function on the evening with higher wind, possibly indicating the breaking-wave aerosol was changing during the longer transit time of the other evening. Aerosol optical depths (AOD) were calculated with the CLidar data by integrating though the boundary layer. The first evening was clear and agreed, within error bars, with the NASA/MODIS overpass. The CLidar AOD on the second evening, which was partly cloudy, was significantly lower than the MODIS value possibly because of an over estimate of the MODIS instrument near clouds.

Barnes, J. E.; Parikh Sharma, N. C.; Kaplan, T.; Clarke, A. D.

2010-12-01

155

Characterization of the atmospheric aerosol by combination of lidar and sun-photometry  

NASA Astrophysics Data System (ADS)

During the summer 2006 an extended observational campaign of atmospheric aerosol has been developed in the area of Granada, South-eastern Spain. From July to the end of September two Cimel CE-318 radiometers have been operated continuously, one at Andalusian Centre for Environmental Studies (CEAMA), located in the urban area of Granada, a non-industrialized medium size city (37.16ºN, 3.61ºW and 680 m a.m.s.l.), and the second one at the Astronomical Observatory of Sierra Nevada (37.06ºN, 3.38ºW and 2896 m a.m.s.l.), with a short horizontal separation between stations that allows us to consider both instrument located in approximately the same vertical column. The Cimel CE-318 measurements have been used to retrieve the aerosol columnar properties, including the columnar volume size distribution, volume scattering phase function, asymmetry factor and single scattering albedo, by means of appropriate inversion procedures. Additionally, at the CEAMA a Raman Lidar system based on a Nd:YAG laser source operating at 1064, 532 and 355 nm and including elastic, polarized and Raman shifted detection has been used to derive profiles of several atmospheric aerosol properties. In this paper we present analyses of the changes and temporal evolution detected in atmospheric aerosol vertical profile. Several long range transport episodes have been detected and back-trajectories analyses and synoptic information have been used in the discussion of results.

Alados-Arboledas, Lucas; Guerrero Rascado, Juan Luis; Lyamani, Hassan; Navas-Guzman, Francisco; Olmo Reyes, Francisco José

2007-10-01

156

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

157

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

158

Compact Efficient Lidar Receiver for Measuring Atmospheric Aerosols  

NASA Technical Reports Server (NTRS)

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

Gili, Christopher; De Young, Russell

2006-01-01

159

Airborne high spectral resolution lidar for profiling aerosol optical properties.  

PubMed

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

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

2008-12-20

160

Temperature measurements made with a combined Rayleigh -Mie and Raman lidar.  

PubMed

The NASA Goddard Space Flight Center stratospheric ozone lidar system has the capability of collecting both Rayleigh -Mie and Raman backscatter data simultaneously at a number of wavelengths. Here we report on an improved method by which temperature can be derived from a combination of the Rayleigh -Mie return at 351-nm lidar channels and the Raman nitrogen return at 382-nm lidar channels. We also examine some common techniques by which temperatures are retrieved from lidar data. Finally, we show results obtained in 1995 during two Network for the Detection of Stratospheric Change intercomparison campaigns at Lauder, New Zealand and Mauna Loa, Hawaii. PMID:18259441

Gross, M R; McGee, T J; Ferrare, R A; Singh, U N; Kimvilakani, P

1997-08-20

161

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

162

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

163

Analysis and Calibration of CRF Raman Lidar Cloud Liquid Water Measurements  

SciTech Connect

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

Turner, D.D. Whiteman, D.N. Russo, F.

2007-10-31

164

Vertically resolved aerosol properties by multi-wavelength lidar measurements  

NASA Astrophysics Data System (ADS)

An approach based on the graphical method of Gobbi and co-authors (2007) is introduced to estimate the dependence on altitude of the aerosol fine mode radius (Rf) and of the fine mode contribution (?) to the aerosol optical thickness (AOT) from three-wavelength lidar measurements. The graphical method of Gobbi and co-authors (2007) was applied to AERONET (AErosol RObotic NETwork) spectral extinction observations and relies on the combined analysis of the Ångstrom exponent (å) and its spectral curvature ?å. Lidar measurements at 355, 532 and 1064 nm were used in this study to retrieve the vertical profiles of å and ?å and to estimate the dependence on altitude of Rf and ?(532 nm) from the å-?å combined analysis. Lidar measurements were performed at the Department of Mathematics and Physics of the Universita' del Salento, in south-eastern Italy. Aerosol from continental Europe, the Atlantic, northern Africa, and the Mediterranean Sea are often advected over south-eastern Italy and as a consequence, mixed advection patterns leading to aerosol properties varying with altitude are dominant. The proposed approach was applied to ten measurement days to demonstrate its feasibility in different aerosol load conditions. The selected days were characterized by AOTs spanning the 0.26-0.67, 0.15-0.39, and 0.04-0.27 range at 355, 532, and 1064 nm, respectively. Mean lidar ratios varied within the 31-83, 32-84, and 11-47 sr range at 355, 532, and 1064 nm, respectively, for the high variability of the aerosol optical and microphysical properties. å values calculated from lidar extinction profiles at 355 and 1064 nm ranged between 0.1 and 2.5 with a mean value ± 1 standard deviation equal to 1.3 ± 0.7. ?å varied within the -0.1-1 range with mean value equal to 0.25 ± 0.43. Rf and ?(532 nm) values spanning the 0.05-0.3 ?m and the 0.3-0.99 range, respectively, were associated with the å-?å data points. Rf and ? values showed no dependence on the altitude. 60% of the data points were in the ?å-å space delimited by the ? and Rf curves varying within 0.80-0.99 and 0.05-0.15 ?m, respectively, for the dominance of fine-mode particles in driving the AOT over south-eastern Italy. Vertical profiles of the linear particle depolarization ratio retrieved from lidar measurements, aerosol products from AERONET sun photometer measurements collocated in space and time, analytical back trajectories, satellite true colour images, and dust concentrations from the BSC-DREAM (Barcelona Super Computing Center-Dust REgional Atmospheric Model) model were used to demonstrate the robustness of the proposed method.

Perrone, M. R.; De Tomasi, F.; Gobbi, G. P.

2014-02-01

165

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

NASA Astrophysics Data System (ADS)

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

Kafle, D. N.; Coulter, R.

2011-12-01

166

Extensive ground-based Lidar and Radiometer Measurements of Aerosol and Cloud for the Comparison and Validation of CALIPSO retrievals  

NASA Astrophysics Data System (ADS)

We present the results of collocated measurements from CCNY ground-based multiwavelength Raman-Mie lidar and a CIMEL Sun/sky radiometer with CALIPSO overpasses near New York City (40.821N,73.949W). The data set consists of 19 days of observations conducted under the clear, hazy, and cloudy skies. In particular, statistical comparisons are made between the CALIPSO Level-2 5-km layer products and the ground-based lidar observations. We find in general excellent correlations exist between both cloud base and cloud top even for multiple deck cases that are not to close. In the clear skies, the CALIPSO aerosol layer tops are consistent with ground-lidar derived PBL heights although the accuracy degrades if capped by cloud layers. In addition, we perform a detailed comparison for smoke and polluted dust entrainments including aerosol classification, derivation of extinction profiles and lidar ratios. Aerosol extinction profiles are shown to be in good agreement when processed directly using the Fernald algorithm. Problems are seen when CALIPSO misidentifies plumes as clouds and processes the extinction data incorrectly. Finally, we derive planetary boundary layer (PBL) heights directly from the CALIPSO level-1B profiles and show reasonable statistical agreement to the Level-2 layer height product. Comparisons to PBL heights in urban areas are also performed.

Wu, Y.; Herman, B.; Gross, B.; Moshary, F.; Ahmed, S.

2008-12-01

167

Study of the atmospheric aerosols, water vapor and temperature by LIDAR  

Microsoft Academic Search

The LIDAR project was established in the year 2000 to study the atmospheric properties of the higher troposphere by means of a lidar technique. The optical properties of the atmosphere in the UV, visible and the Near IR regions of the spectra, the vertical aerosol and water vapor distribution, and atmospheric temperature are the parameters measured on regular basis. Aerosols

Valentin Simeonov; Hubert van den Bergh; Marian Taslakov; Ioan Balin; Remo Nessler; Pablo Ristori

168

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

NASA Technical Reports Server (NTRS)

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

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

1991-01-01

169

Simulation of coherent Doppler wind lidar measurement from space based on CALIPSO lidar global aerosol observations  

NASA Astrophysics Data System (ADS)

The performance of a space-based 2.1-?m coherent Doppler wind lidar (CDWL) measurement at a single laser shot in clear-air conditions is computer simulated, based on the coherent Doppler lidar theory developed in the recent decades, and using the global aerosol distribution derived from one year (March 2007-February 2008) of the CALIPSO lidar measurements. The accuracy of radial wind velocity good estimates and the fraction of good estimates, depending on backscattered signals from aerosols, generally decrease with altitude. A critical altitude is defined as the altitude below which the good estimate fraction of velocity estimates is larger than 90.0%. With a laser pulse energy of 250mJ at an off-nadir pointing angle of 45°, a telescope of 1m in diameter and a vertical range resolution of ˜800m, this critical altitude can reach an altitude of 4.0-5.0km between 20°S and 40°N where dust and biomass burning aerosols are ubiquitous. The critical altitude gradually decreases as approaching the two poles and drops to 0.5-1.5km in the polar regions. When the laser pulse energy is reduced to 100mJ, the critical altitude is generally decreased by ˜0.5km and can still reach an altitude of 3.5-4.5km in the dust and smoke aerosol enriched tropical and subtropical regions. A laser pulse energy of only a few millijoules can still achieve velocity measurements with an RMS error smaller than 1ms-1 and a good estimate fraction better than 90% in the lowest kilometers of the troposphere.

Wu, Dong; Tang, Jiayuan; Liu, Zhaoyan; Hu, Yongxiang

2013-06-01

170

Volcanic eruptions and the increases in the stratospheric aerosol content: Lidar measurements from 1982 to 1986  

Microsoft Academic Search

The results of the observation for stratospheric aerosols which were carried out since the autumn of 1982 by using the NIES large lidar are described. Specifications of the lidar system are shown. The lidar has two wavelenghts of 1.06 and 0.53 micrometers. The 0.53 micrometer is mainly used for the stratospheric aerosols, because the PMT for 0.53 micrometers has higher

S. Hayashida; Y. Iikura; H. Shimizu; Y. Sasano; H. Nakane; N. Sugimoto; I. Matsui; N. Takeuchi

1986-01-01

171

Long term stratospheric aerosol lidar measurements in Kyushu  

NASA Technical Reports Server (NTRS)

Lidar soundings of the stratospheric aerosols have been made since 1972 at Fukuoka, Kyushu Island of Japan. Volcanic clouds from eruptions of La Soufriere, Sierra Negra, St. Helens, Uluwan, Alaid, unknown volcano, and El Chichon were detected one after another in only three years from 1979 to 1982. In july 1991 strong scattering layers which were originated from the serious eruptions of Pinatubo in June and were almost comparable to the El Chichon clouds were detected. Volcanic clouds from pinatubo and other volcanos mentioned are examined and carefully compared to each other and to the wind and temperature which was measured by Fukuoka Meteorological Observatory almost at the same time as the lidar observation was made.

Fujiwara, Motowo

1992-01-01

172

Raman lidar calibration for the DMSP SSM\\/T-2 microwave water vapor sensor  

Microsoft Academic Search

Campaigns were conducted at the Pacific Missile Range Facility, Barking Sands, Kauai, investigating Raman lidar as a method to improve calibration of the DMSP SSM\\/T-2 microwave water vapor profiling instrument. Lidar mixing ratios were calibrated against AIR and Vaisala radiosondes and the calibration was tested in the vicinity of clouds. Above 6 km, radiosondes reported anomalously low relative humidity in

John Wessel; Steven M. Beck; Yat C. Chan; Robert W. Farley; Jerry A. Gelbwachs

2000-01-01

173

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

174

Retrieving aerosol microphysical properties by Lidar-Radiometer Inversion Code (LIRIC) for different aerosol types  

NASA Astrophysics Data System (ADS)

(Lidar-Radiometer Inversion Code) is applied to combined lidar and Sun photometer data from Granada station corresponding to different case studies. The main aim of this analysis is to evaluate the stability of LIRIC output volume concentration profiles for different aerosol types, loadings, and vertical distributions of the atmospheric aerosols. For this purpose, in a first part, three case studies corresponding to different atmospheric situations are analyzed to study the influence of the user-defined input parameters in LIRIC when varied in a reasonable range. Results evidence the capabilities of LIRIC to retrieve vertical profiles of microphysical properties during daytime by the combination of the lidar and the Sun photometer systems in an automatic and self-consistent way. However, spurious values may be obtained in the lidar incomplete overlap region depending on the structure of the aerosol layers. In a second part, the use of a second Sun photometer located in Cerro Poyos, in the same atmospheric column as Granada but at higher altitude, allowed us to obtain LIRIC retrievals from two different altitudes with independent Sun photometer measurements in order to check the self-consistency and robustness of the method. Retrievals at both levels are compared, providing a very good agreement (differences below 5 µm3/cm3) in those cases with the same aerosol type in the whole atmospheric column. However, some assumptions such as the height independency of parameters (sphericity, size distribution, or refractive index, among others) need to be carefully reviewed for those cases with the presence of aerosol layers corresponding to different types of atmospheric aerosols.

Granados-Muñoz, M. J.; Guerrero-Rascado, J. L.; Bravo-Aranda, J. A.; Navas-Guzmán, F.; Valenzuela, A.; Lyamani, H.; Chaikovsky, A.; Wandinger, U.; Ansmann, A.; Dubovik, O.; Grudo, J. O.; Alados-Arboledas, L.

2014-04-01

175

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

NASA Technical Reports Server (NTRS)

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

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

1998-01-01

176

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

SciTech Connect

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

Whiteman, D. [National Aeronautics and Space Administration, Greenbelt, MD (United States). Goddard Space Flight Center; Turner, D. [Pacific Northwest National Lab., Richland, WA (United States); Evans, K. [Joint Center for Earth Systems Technology, Baltimore, MD (United States)] [and others

1998-04-01

177

Middle Atmosphere Temperature Climatology at Mauna Loa from Rayleigh/Raman Lidar Measurements  

NASA Technical Reports Server (NTRS)

The JPL Lidar at Mauna Loa Observatory (MLO) continues to make regular measurements of ozone, temperature and aerosol profiles for the Network for the Detection of Stratospheric Change (NDSC) program.

McDermid, I. S.; Leblanc, T.; Cageao, R.; Beyerle, G.; Walsh, D.

1998-01-01

178

NASA/GSFC Scanning Raman Lidar Measurements of Water Vapor and Clouds during the International H2O Project (IHOP) Field Campaign  

NASA Technical Reports Server (NTRS)

The NASA/GSFC Scanning Raman Lidar (SFL) acquired approximately 200 hours of water vapor, aerosol and cloud measurements during the IHOP field campaign. The detailed water vapor structure of events such as a dryline passage and internal bores were revealed. We discuss the error characteristics of the instrument as well as the water vapor and cirrus cloud structure during the 19-20 June bore event.

Whiteman, David; Demoz, Belay; DiGirolamo, Paolo; Wang, Zhi-En; Evans, Keith; Lin, Ruei-Fong

2003-01-01

179

Airborne lidar measurements of El Chichon stratospheric aerosols, January 1984  

NASA Technical Reports Server (NTRS)

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

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

1987-01-01

180

Airborne lidar measurements of El Chichon stratospheric aerosols  

NASA Technical Reports Server (NTRS)

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

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

1985-01-01

181

Assessment of aloft aerosol layers by ground-based lidar, satellite CALIPSO and model  

NASA Astrophysics Data System (ADS)

Aloft aerosol layers injected from dust storms and biomass burning are often transported over the long-distance, thus playing important roles in climate radiative forcing and air quality in the regional and continental scale. In particular, they are critical to satellite remote sensing of air quality, e.g. using satellite column aerosol optical depth (AOD) to evaluate surface PM2.5 concentration, because the aloft aerosol layer can make a substantial contribution to total AOD. These aloft aerosol plumes have been extensively observed or identified by the ground-lidar and space-borne lidar CALIOP/CALIPSO, as well as the global aerosol transport such as NRL-NAAPS. In this study, the aloft aerosol layers are investigated with a regional NOAA-CREST Lidar Network (CLN) in the East Coast of U.S., spaceborne lidar CAIPSO observations and NAAPS model forecast. We first analyze the height distribution and seasonal occurrence of aloft aerosol plumes from the multi-year CLN-lidar dataset. We also explore specific aloft aerosol layers and type classifications between NAAPS-model and CLN-lidar observations to asses NAAPS with special attention to time slices when MODIS AOD assimilation is present or not. Moreover, we assess the potential of NAAPS to identify and separate between aloft aerosol layers ('unclear' sky) and the non-aloft-layer ('clear' sky). This identification is very important in filtering the use of satellite AOD retrievals in potential PM2.5 estimators.

Wu, Y.; Cordero, L.; Nazmi, C.; Gross, B.; Moshary, F.; Ahmed, S. A.

2013-12-01

182

ESYRO Lidar system developments for troposphere monitoring of aerosols and clouds properties  

NASA Astrophysics Data System (ADS)

Aiming the remote sensing low cost, up-gradable and modular tools development for monitoring relevant atmospheric parameters and processes in the whole troposphere (from 250 m to 12-15 Km altitude), a new configuration LIDAR system, i.e. ESYROLIDAR, dedicated for tropospheric aerosols and clouds high temporal (minutes) and spatial resolutions (meters) monitoring have been developed and tested. This extremely up-gradable configuration of ESYROLIDAR is based on: a multi -wavelengths (1064, 532 and 355 nm) powerful (200, 100 and 45 mJ/pulse) and relatively high variable repetition rate (up to 30 Hz) Nd:YAG pulsed laser, a large Newtonian telescope (40 cm diameter of collector mirror) and a new opto-mechanics detection module built in an original "eye geometry" consideration. The firsts tests and measurements were performed at the site of Science and Technology Park TehnopolIS (Iasi city located on the northeastern region of Romania), using a basic configuration with a 532 nm elastic detection with depolarization study module. Different types of clouds up to 12 km in daylight are highlighted from this first measurement. Measurements and tests made in other recent campaigns for 355 nm elastic channel are also presented. The ability of the new LIDAR system to determine the height of planetary boundary layer (PBL) determined from the LIDAR signals, as well as the aerosols load and optical parameters (extinction and backscatter) and the evaluation of atmospheric dynamics at high spatial-temporal resolutions are clearly confirmed. This paper presents the ESYROLIDAR basic configuration with its two VIS elastic channels (532 nm, parallel and cross). The first measurements made with the UV (355 nm - interchangeable channel) and VIS (532 nm) elastic channels are illustrated by typical examples. The quality of ESYROLIDAR atmospheric profiles is based on advantages of low divergence (0.15 mrad), relatively high repetition rate (30 Hz) and the coaxial UV-VIS-NIR .The present challenges are first a new robust more automatized alignment system and second the integration of more Raman detection channels i.e. Raman H2O water vapor at 407 nm. This system is the base of the ROmanian LIdar NETwork (ROLINET).

Tudose, Ovidiu-Gelu; Cazacu, Marius-Mihai; Timofte, Adrian; Balin, Ioan

2011-10-01

183

Mie lidar observations of lower tropospheric aerosols and clouds.  

PubMed

Mie lidar system is developed at Laser Science and Technology Centre, Delhi (28.38°N, 77.12°E) by using minimal number of commercially available off-the-shelf components. Neodymium Yttrium Aluminum Garnet (Nd:YAG) laser operating at 1064nm with variable pulse energies between 25 and 400 mJ with 10 Hz repetition rate and 7ns pulse duration is used as a transmitter and off-axis CASSEGRAIN telescope with 100mm diameter as a receiver. Silicon avalanche photodiode (Si-APD) module with built-in preamplifier and front-end optics is used as detector. This system has been developed for the studies of lower tropospheric aerosols and clouds. Some experiments have been conducted using this set up and preliminary results are discussed. The characteristics of backscattered signals for various transmitter pulse energies are also studied. Atmospheric aerosol extinction coefficient values are calculated using Klett lidar inversion algorithm. The extinction coefficient, in general, falls with range in the lower troposphere and the values lie typically in the range 7.5×10(-5) m(-1) to 1.12×10(-4) m(-1) in the absence of any cloud whereas this value shoots maximum up to 1.267×10(-3) m(-1) (peak extinction) in the presence of clouds. PMID:21975046

Veerabuthiran, S; Razdan, A K; Jindal, M K; Dubey, D K; Sharma, R C

2011-12-15

184

Measurement of the Vertical Distribution of Aerosol by Globally Distributed MP Lidar Network Sites  

NASA Technical Reports Server (NTRS)

The global distribution of aerosol has an important influence on climate through the scattering and absorption of shortwave radiation and through modification of cloud optical properties. Current satellite and other data already provide a great amount of information on aerosol distribution. However there are critical parameters that can only be obtained by active optical profiling. For aerosol, no passive technique can adequately resolve the height profile of aerosol. The aerosol height distribution is required for any model for aerosol transport and the height resolved radiative heating/cooling effect of aerosol. The Geoscience Laser Altimeter System (GLAS) is an orbital lidar to be launched by 2002. GLAS will provide global measurements of the height distribution of aerosol. The sampling will be limited by nadir only coverage. There is a need for local sites to address sampling, and accuracy factors. Full time measurements of the vertical distribution of aerosol are now being acquired at a number of globally distributed MP (micro pulse) lidar sites. The MP lidar systems provide profiling of all significant cloud and aerosol to the limit of signal attenuation from compact, eye safe instruments. There are currently six sites in operation and over a dozen planned. At all sites there are a complement of passive aerosol and radiation measurements supporting the lidar data. Four of the installations are at Atmospheric Radiation Measurement program sites. The aerosol measurements, retrievals and data products from the network sites will be discussed. The current and planned application of data to supplement satellite aerosol measurements is covered.

Spinhirne, James; Welton, Judd; Campbell, James; Starr, David OC. (Technical Monitor)

2001-01-01

185

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

SciTech Connect

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

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

2013-08-27

186

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

187

Observation of dust aerosol profile and atmospheric visibility of Xi'an with Mie scattering lidar  

NASA Astrophysics Data System (ADS)

Dust aerosol or sand storm has become the popular attention topic of the world currently. In order to understand and study the aerosol optical properties, particularly for dust aerosol produced in the spring weather condition, and to investigate their effects on atmospheric pollution status, a Mie scattering lidar was developed to detect the time and spatial distribution of the aerosol and the atmospheric visibility at Xi'an, China. The lidar system employs a Nd:YAG pulsed laser at a eye-safe wavelength of 355nm as a transmitter, and a Schmidt-Cassegrain telescope as a receiver. A spectroscope filter combined with a high-resolution grating was used to separate the main lidar returns and to block the solar background simultaneously for daytime measurement. The observation experiments with lidar have been carried out from the spring of 2007. The data of the extinction coefficients of aerosol and atmospheric visibility taken under the different atmospheric conditions are demonstrated. The comparison results of visibility measurement using lidar and other tool show that the lidar system is feasible, and the aerosol observation results show that the main aerosol pollution of Xi'an is from the floating dust aerosol, which is usually suspended at a height of near 1km.

Liu, Jun; Hua, Dengxin

2008-10-01

188

Variability of aerosol and spectral lidar and backscatter and extinction ratios of key aerosol types derived from selected Aerosol Robotic Network locations  

Microsoft Academic Search

The lidar (extinction-to-backscatter) ratios at 0.55 and 1.02 ?m and the spectral lidar, extinction, and backscatter ratios of climatically relevant aerosol species are computed on the basis of selected retrievals of aerosol properties from 26 Aerosol Robotic Network (AERONET) sites across the globe. The values, obtained indirectly from sky radiance and solar transmittance measurements, agree very well with values from

Christopher Cattrall; John Reagan; Kurt Thome; Oleg Dubovik

2005-01-01

189

Variability of aerosol and spectral lidar and backscatter and extinction ratios of key aerosol types derived from selected Aerosol Robotic Network locations  

Microsoft Academic Search

The lidar (extinction-to-backscatter) ratios at 0.55 and 1.02 mum and the spectral lidar, extinction, and backscatter ratios of climatically relevant aerosol species are computed on the basis of selected retrievals of aerosol properties from 26 Aerosol Robotic Network (AERONET) sites across the globe. The values, obtained indirectly from sky radiance and solar transmittance measurements, agree very well with values from

Christopher Cattrall; John Reagan; Kurt Thome; Oleg Dubovik

2005-01-01

190

Two-wavelength backscattering lidar for stand off detection of aerosols  

NASA Astrophysics Data System (ADS)

Following article presents LIDAR for stand off detection of aerosols which was constructed in Institute of Optoelectronics in Military University of Technology. LIDAR is a DISC type system (DIfferential SCattering) and is based on analysis of backscattering signal for two wavelengths (?1 = 1064 nm and ?2 = 532 nm) - the first and the second harmonic of Nd:YAG laser. Optical receiving system is consisted of aspherical mirror lens, two additional mirrors and a system of interference filters. In detection system of LIDAR a silicon avalanche photodiode and two different amplifiers were used. Whole system is mounted on a specialized platform designed for possibility of LIDAR scanning movements. LIDAR is computer controlled. The compiled software enables regulation of the scanning platform work, gain control, and control of data processing and acquisition system. In the article main functional elements of LIDAR are shown and typical parameters of system work and construction are presented. One presented also first results of research with use of LIDAR. The aim of research was to detect and characterize scattering aerosol, both natural and anthropogenic one. For analyses of natural aerosols, cumulus cloud was used. For analyses of anthropogenic aerosols one used three various pyrotechnic mixtures (DM11, M2, M16) which generate smoke of different parameters. All scattering centers were firstly well described and theoretical analyses were conducted. Results of LIDAR research were compared with theoretical analyses and general conclusions concerning correctness of LIDAR work and its application were drawn.

Mierczyk, Zygmunt; Zygmunt, Marek; Gawlikowski, Andrzej; Gietka, Andrzej; Kaszczuk, Miroslawa; Knysak, Piotr; Mlodzianko, Andrzej; Muzal, Michal; Piotrowski, Wies?aw; Wojtanowski, Jacek

2008-10-01

191

LOSA-MS lidar for investigation of aerosol fields in the troposphere  

Microsoft Academic Search

The LOSA-MS combined small-sized single-wavelength backscatter lidar is described whose operation is based on the effects of Raman and elastic scattering. To extend the range of sounding, lidar returns are registered simultaneously in analog and photon counting regimes. A photodetector system for wavelength and polarization selection of lidar signals is described. The basic physical principles of laser sounding and methods

G. S. Bairashin; Yurii S. Balin; Arkadii D. Ershov; Grigorii P. Kokhanenko; I. E. Penner

2005-01-01

192

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

193

Atlantic atmospheric aerosol studies 1. Program overview and airborne lidar  

SciTech Connect

During the period 1988-1990, studies of atmospheric aerosol have been made over the Atlantic. These include measurement programs out of Ascension Island (8{degrees}S, 14{degrees}W), the Azores (38{degrees}N, 25{degrees}W), Iceland (63{degrees}N, 23{degrees}W), and from the United Kingdom over the Northeast Atlantic. For these studies the equipment deployed included an airborne backscatter lidar (operating at 10.6 {mu}m), airborne particle-sounding probes, ground-based lidars (operating at 10.6, 0.53, and 0.35 {mu}m), balloon radiosondes, and a Sun-tracking photometer. In addition, standard meteorological information has been incorporated along with, when appropriate, data from the SAGE II limb-sounding satellite. The present paper thus introduces an overview of the program together with an outline of the technology, measurement characteristics, and performance of the airborne equipment that determined the strategic planning of much of the work. The measurements themselves, made in the relatively clean period for the atmosphere before the Mount Pinatubo eruption, will be presented in a subsequent series of papers. 26 refs., 5 figs., 3 tabs.

Alejandro, S.B.; Koenig, G.G.; Bedo, D. [Phillips Lab., Hanscom Air Force Base, MA (United States)] [and others] [Phillips Lab., Hanscom Air Force Base, MA (United States); and others

1995-01-20

194

Use of probability distribution functions for discriminating between cloud and aerosol in lidar backscatter data  

Microsoft Academic Search

In this paper, we describe the algorithm that will be used during the upcoming Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) mission for discriminating between clouds and aerosols detected in two-wavelength backscatter lidar profiles. We first analyze single-test and multiple-test classification approaches based on one-dimensional (1-D) and multidimensional probability distribution functions (PDFs) in the context of a two-class feature

Zhaoyan Liu; Mark A. Vaughan; David M. Winker; Chris A. Hostetler; Lamont R. Poole; Dennis Hlavka; William Hart; Matthew McGill

2004-01-01

195

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

Microsoft Academic Search

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

Masaharu Imaki; Takao Kobayashi

2005-01-01

196

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

NASA Technical Reports Server (NTRS)

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

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

2009-01-01

197

Balloon-borne and Raman lidar observations of Asian dust and cirrus cloud properties over Tsukuba, Japan  

NASA Astrophysics Data System (ADS)

vertical distributions of the microphysical and optical properties of tropospheric aerosols and cirrus cloud were measured using an instrumented balloon and a ground-based Raman lidar over Tsukuba, Japan (36°N, 140°E), during the Asian dust events on 9 and 21 May 2007 to investigate the influence of Asian mineral dust on ice cloud formation in the upper troposphere. The instrumented balloon measured the particle size distribution, ice crystal images, dew/frost point, relative humidity, and temperature. The Raman lidar measured the particle backscattering and extinction coefficients and the depolarization ratio at a wavelength of 532 nm. The results of the balloon measurements showed that supermicrometer (0.7 to 2.8 µm in optical-equivalent radius) dust particles and ice crystals (10 to 400 µm in maximum dimension) were present in the upper troposphere (8 to 12 km in altitude), with number concentrations varying from 5 × 10-3 to 0.6 cm-3 for dust and from 5 × 10-3 to 0.15 cm-3 for ice crystals. The Raman lidar measurement indicated that the particle depolarization ratios were 15 to 35% in the altitude range of 6 to 12 km, indicating the predominance of nonspherical particles in the region. The temperature ranged from -33 to -63°C, and the relative humidity with respect to ice (RHi), estimated from the total (vapor plus condensate) water content obtained with the Snow White hygrometer in the cloud, was 130% at maximum on 9 May, which was close to the activation point of Asian mineral dust as ice nuclei to form ice crystals.

Sakai, Tetsu; Orikasa, Narihiro; Nagai, Tomohiro; Murakami, Masataka; Tajiri, Takuya; Saito, Atsushi; Yamashita, Katsuya; Hashimoto, Akihiro

2014-03-01

198

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

199

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

NASA Technical Reports Server (NTRS)

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

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

1998-01-01

200

A theoretical/experimental program to develop active optical pollution sensors: Quantitative remote Raman lidar measurements of pollutants from stationary sources  

NASA Technical Reports Server (NTRS)

Typical pollutant gas concentrations at the stack exits of stationary sources can be estimated to be about 500 ppm under the present emission standards. Raman lidar has a number of advantages which makes it a valuable tool for remote measurements of these stack emissions. Tests of the Langley Research Center Raman lidar at a calibration tank indicate that night measurements of SO2 concentrations and stack opacity are possible. Accuracies of 10 percent are shown to be achievable from a distance of 300 m within 30 min integration times for 500 ppm SO2 at the stack exits. All possible interferences were examined quantitatively (except for the fluorescence of aerosols in actual stack emissions) and found to have negligible effect on the measurements. An early test at an instrumented stack is strongly recommended.

Poultney, S. K.; Brumfield, M. L.; Siviter, J. S.

1975-01-01

201

Lidar measurements of the post-fuego stratospheric aerosol  

NASA Technical Reports Server (NTRS)

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

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

1976-01-01

202

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

PubMed

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

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

2000-10-20

203

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.

204

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

NASA Astrophysics Data System (ADS)

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

Talianu, Camelia; Labzovskii, Lev; Toanca, Florica

2014-05-01

205

Remote detection and identification of biological aerosols using a femtosecond terawatt lidar system  

NASA Astrophysics Data System (ADS)

We demonstrate experimentally the first range-resolved detection and identification of biological aerosols in the air by non-linear lidar. Ultra-short terawatt laser pulses are used to induce two-photon-excited fluorescence (2PEF) in riboflavin-containing particles at a remote location. We show that, in the case of amino acid detection, 2PEF-lidar should be more efficient than linear 1PEF-lidar beyond a typical distance of 2 km, because it takes advantage of the higher atmospheric transmission at the excitation wavelengths. 2PEF-lidar moreover allows size measurement by pump-probe schemes, and pulse shaping may improve the detection selectivity.

Méjean, G.; Kasparian, J.; Yu, J.; Frey, S.; Salmon, E.; Wolf, J.-P.

206

AGLITE: a multiwavelength lidar for aerosol size distributions, flux, and concentrations  

NASA Astrophysics Data System (ADS)

We report on the design, construction and operation of a new multiwavelength lidar developed for the Agricultural Research Service of the United States Department of Agriculture and its program on particle emissions from animal production facilities. The lidar incorporates a laser emitting simultaneous, pulsed Nd laser radiation at 355, 532 and 1064 nm at a PRF of 10 kHz. Lidar backscatter and extinction data are modeled to extract the aerosol information. All-reflective optics combined with dichroic and interferometric filters permit all the wavelength channels to be measured simultaneously, day or night, using photon counting by PMTs, an APD, and high speed scaling. The lidar is housed in a transportable trailer for all-weather operation at any accessible site. The laser beams are directed in both azimuth and elevation to targets of interest. We describe application of the lidar in a multidisciplinary atmospheric study at a swine production farm in Iowa. Aerosol plumes emitted from the hog barns were prominent phenomena, and their variations with temperature, turbulence, stability and feed cycle were studied, using arrays of particle samplers and turbulence detectors. Other lidar measurements focused on air motion as seen by long duration scans of the farm region. Successful operation of this lidar confirms the value of multiwavelength, eye-safe lidars for agricultural aerosol measurements.

Wilkerson, Thomas D.; Zavyalov, Vladimir V.; Bingham, Gail E.; Swasey, Jason A.; Hancock, Jed J.; Crowther, Blake G.; Cornelsen, Scott S.; Marchant, Christian; Cutts, James N.; Huish, David C.; Earl, Curtis L.; Andersen, Jan M.; Cox, McLain L.

2006-06-01

207

Influence of daylight and noise current on cloud and aerosol observations by spaceborne elastic scattering lidar.  

PubMed

The influence of daylight and noise current on cloud and aerosol observations by realistic spaceborne lidar was examined by computer simulations. The reflected solar radiations, which contaminate the daytime return signals of lidar operations, were strictly and explicitly estimated by accurate radiative transfer calculations. It was found that the model multilayer cirrus clouds and the boundary layer aerosols could be observed during the daytime and the nighttime with only a few laser shots. However, high background noise and noise current make it difficult to observe volcanic aerosols in middle and upper atmospheric layers. Optimal combinations of the laser power and receiver field of view are proposed to compensate for the negative influence that is due to these noises. For the computer simulations, we used a realistic set of lidar parameters similar to the Experimental Lidar in-Space Equipment of the National Space Development Agency of Japan. PMID:18324021

Nakajima, T Y; Imai, T; Uchino, O; Nagai, T

1999-08-20

208

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

PubMed

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

Imaki, Masaharu; Kobayashi, Takao

2005-10-01

209

Six-channel polychromator design and implementation for the UPC elastic\\/Raman lidar  

Microsoft Academic Search

A 6-channel dichroic-based polychromator is presented as the spectrally selective unit for the U.P.C. elastic\\/Raman lidar. Light emission is made at 355-nm (ultraviolet, UV), 532-nm (visible, VIS) and 1064-nm (near infrared, NIR) wavelengths. In reception, the polychromator is the spectral separation unit that separates the laser backscattered composite return into 3 elastic (355, 532, 1064-nm wavelengths) and 3 Raman channels

Dhiraj Kumar; Francesc Rocadenbosch; Michaël Sicard; Adolfo Comeron; Constantino Muñoz; Diego Lange; Sergio Tomás; Eduard Gregorio

2011-01-01

210

Measurement of multiple scattering effects with a polarization Raman elastic-backscatter lidar  

NASA Technical Reports Server (NTRS)

A new method for the determination of multiple scattering effects is described. A polarization Raman elastic backscatter lidar is used, which allows the measurement of the depolarization of both the elastically backscattered light and the light Raman scattered from nitrogen molecules. With this technique the depolarization effect due to multiple scattering can be separated from single scattering polarization. Presented here are a short discussion of the idea and a measurement example.

Wandinger, Ulla; Ansmann, Albert; Weitkamp, Claus; Michaelis, Walfried

1992-01-01

211

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

Microsoft Academic Search

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

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

1984-01-01

212

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

PubMed

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

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

2013-08-01

213

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

NASA Technical Reports Server (NTRS)

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

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

2006-01-01

214

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

NASA Astrophysics Data System (ADS)

The NASA Langley Research Center (LaRC) airborne High Spectral Resolution Lidar (HSRL-1) on the NASA B200 aircraft has acquired large datasets of aerosol extinction (532nm), backscatter (532 and 1064nm), and depolarization (532 and 1064nm) profiles during 349 science flights in 19 field missions across North America since 2006. The extinction-to-backscatter ratio ("lidar ratio"), aerosol depolarization ratios, and backscatter color ratio measurements from HSRL-1 are scale-invariant parameters that depend on aerosol type but not concentration. These four aerosol intensive parameters are combined to qualitatively classify HSRL aerosol measurements into eight separate composition types. The classification methodology uses models formed from "training cases" with known aerosol type. The remaining measurements are then compared with these models using the Mahalanobis distance. Aerosol products from the CALIPSO satellite include aerosol type information as well, which is used as input to the CALIPSO aerosol retrieval. CALIPSO aerosol types are inferred using a mix of aerosol loading-dependent parameters, estimated aerosol depolarization, and location, altitude, and surface type information. The HSRL instrument flies beneath the CALIPSO satellite orbit track, presenting the opportunity for comparisons between the HSRL aerosol typing and the CALIPSO Vertical Feature Mask Aerosol Subtype product, giving insight into the performance of the CALIPSO aerosol type algorithm. We find that the aerosol classification from the two instruments frequently agree for marine aerosols and pure dust, and somewhat less frequently for pollution and smoke. In addition, the comparison suggests that the CALIPSO polluted dust type is overly inclusive, encompassing cases of dust combined with marine aerosol as well as cases without much evidence of dust. Qualitative classification of aerosol type combined with quantitative profile measurements of aerosol backscatter and extinction has many useful applications. The HSRL products are used to apportion AOT by type and vertical location in the column, and to characterize the frequency of cases where multiple types are present in the column. Resolving scenes with multiple types in the column is not possible with passive imaging radiometer and polarimeter measurements. The HSRL aerosol type also has higher resolution than the CALIPSO layer-wise product and provides insight into the performance of CALIPSO layer separation. Information about the vertical distribution of aerosol types is useful for estimating radiative forcing, understanding aerosol lifetime and transport, and assessing the predictions of transport models. CALIPSO has been a pathfinder, providing the first long-term global data set of aerosol vertical distribution. Based on our results, a future satellite lidar similar to CALIPSO, but with the addition of polarization sensitivity at 1064 nm and the HSRL technique at 532 nm, could provide a significant advance in characterizing the vertical distribution of aerosol.

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

2012-12-01

215

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

NASA Technical Reports Server (NTRS)

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

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

2008-01-01

216

Applications of GLAS Satellite Lidar Cloud, Aerosol and PBL Measurements at High Spatial Resolution  

Microsoft Academic Search

The Geoscience Laser Altimeter System, GLAS, beginning in 2003, provides space borne lidar observations of global clouds and aerosol from polar orbit. The measurements in fall 2003 and spring 2004 include highly sensitive aerosol detection and profiling by photon counting detection at 532 nm wavelength to backscatter cross section below 10-7 1\\/m-sr. Data products from the measurements include aerosol optical

J. D. Spinhirne; S. P. Palm

2007-01-01

217

Plume detection and tracking using Doppler lidar aerosol and wind data  

Microsoft Academic Search

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

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

1999-01-01

218

Aerosol profiles determined with lidar and sun-photometer over the Pearl River Delta, China.  

NASA Astrophysics Data System (ADS)

The priority program "Megacities-Megachallenge - Informal Dynamics of Global Change" is a large interdisciplinary project funded by the German Research Foundation (DFG). One of the subproject deals with mega-urbanisation in the Pearl River Delta, South-China, with special respect to particulate air pollution and public health. In the frame of this subproject the vertical distribution of aerosol optical properties are investigated by measurements with the multiwavelength-Raman-polarization lidar PollyXT of the IfT. The instrument can measure the particle backscatter coefficient at 355 nm, 532 nm, and 1064 nm, the particle extinction coefficients at 355 nm and 532 nm, and the particle linear depolarization ratio at 532 nm. These measurements are supported by a dual-polar sun photometer that provides height integrated data as the aerosol optical depth and the degree of linear depolarization. These instruments are placed at the East campus of the Sun Yat-sen University in Guangzhou, China. Guangzhou and the Pearl River Delta is a developing area with currently around 11 Million inhabitants. The measurements started in November 2011 and are supposed to continue for at least half a year covering the late autumn and winter season and parts of the spring season. Extensions of the measurements towards a whole seasonal cycle are planned. Thus, different meteorological conditions will lead to particle transport from several source regions. Different aerosol types are expected to be observed during the measurement period: urban particles from local and regional sources as well as dust from the deserts in Central Asia. The observed particles can be distinguished by analyzing their optical properties at several wavelengths. In particular, the depolarization measurements from both instruments promise a better determination of the particle shape.

Heese, B.; Althausen, D.; Bauditz, M.; Deng, R.; Bao, R.; Li, Z.

2012-04-01

219

Wavelength dependence of coherent and incoherent satellite-based lidar measurements of wind velocity and aerosol backscatter  

NASA Technical Reports Server (NTRS)

The results are presented of a capability study of Earth orbiting lidar systems, at various wavelengths from 1.06 to 10.6 microns, for the measurement of wind velocity and aerosol backscatter, and for the detection of clouds. Both coherent and incoherent lidar systems were modeled and compared for the aerosol backscatter and cloud detection applications.

Kavaya, M. J.; Huffaker, R. M.

1986-01-01

220

Meteorological observation with Doppler and Raman lidars and comparison with numerical weather simulations  

NASA Astrophysics Data System (ADS)

Meteorological observation data such as temperature, humidity, wind speed and wind direction are important for validating and improving numerical weather simulation models. Lidar is an effective method for acquiring such data with high range resolution and short time intervals. In this study, we carried out a field observation with coherent Doppler Lidar and Raman Lidar systems at the coastal area of Yokosuka, Japan, and compared the observed data with the results of numerical weather simulations. We obtained the vertical profiles of horizontal wind speeds and wind directions by Doppler Lidar with 65 m vertical range resolution, and the vertical profiles of the water vapor mixing ratio by Raman Lidar with 20 m vertical range resolution at the lower atmospheric boundary layer (200-600 m height from ground level). These data were acquired at time intervals of 10 minutes. We found an interesting phenomenon from observed data indicating that, under weak wind conditions, water vapor in the atmosphere significantly increased just after a definite change in wind direction from land breeze to sea breeze. A similar phenomenon was also predicted by the numerical weather simulation with the same meteorological and terrestrial conditions. We analyzed the numerical results and found that the change in water vapor mentioned above is mainly caused by the difference between the evaporation from land and sea surfaces, which were located upwind of the land and sea breezes, respectively.

Tamura, Hidetoshi; Kihara, Naoto; Fujii, Takashi; Fukuchi, Tetsuo; Wada, Koji; Hirakuchi, Hiromaru

2012-11-01

221

Linear Raman spectroscopy on aqueous aerosols: influence of nonlinear effects on detection limits  

Microsoft Academic Search

The influence of stimulated Raman scattering on the characterization of aqueous aerosols by linear Raman spectroscopy was studied experimentally. Raman scattering from a chain of microdroplets was excited by an argon ion laser. Holographic Raman filters, a spectrograph and a cryogenically cooled CCD detector were used to record the spectra. A procedure to estimate the detection limits of Raman instrumentation

R. Vehring

1998-01-01

222

Volcanic eruptions and the increases in the stratospheric aerosol content: Lidar measurements from 1982 to 1986  

NASA Astrophysics Data System (ADS)

The results of the observation for stratospheric aerosols which were carried out since the autumn of 1982 by using the NIES large lidar are described. Specifications of the lidar system are shown. The lidar has two wavelenghts of 1.06 and 0.53 micrometers. The 0.53 micrometer is mainly used for the stratospheric aerosols, because the PMT for 0.53 micrometers has higher sensitivity that that for 1.06 micrometers and the total efficiency is higher in the former. A switching circuit is used to control the PMT gain for avoiding signal induced noise in PMT. For the last four years, the stratospheric aerosol layer which was significantly perturbed by the El Chichon volcanic eruption was observed. The scattering ratio profiles observed from 1982 through 1983 are given.

Hayashida, S.; Iikura, Y.; Shimizu, H.; Sasano, Y.; Nakane, H.; Sugimoto, N.; Matsui, I.; Takeuchi, N.

1986-08-01

223

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

NASA Technical Reports Server (NTRS)

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

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

2010-01-01

224

Volcanic eruptions and the increases in the stratospheric aerosol content: Lidar measurements from 1982 to 1986  

NASA Technical Reports Server (NTRS)

The results of the observation for stratospheric aerosols which were carried out since the autumn of 1982 by using the NIES large lidar are described. Specifications of the lidar system are shown. The lidar has two wavelenghts of 1.06 and 0.53 micrometers. The 0.53 micrometer is mainly used for the stratospheric aerosols, because the PMT for 0.53 micrometers has higher sensitivity that that for 1.06 micrometers and the total efficiency is higher in the former. A switching circuit is used to control the PMT gain for avoiding signal induced noise in PMT. For the last four years, the stratospheric aerosol layer which was significantly perturbed by the El Chichon volcanic eruption was observed. The scattering ratio profiles observed from 1982 through 1983 are given.

Hayashida, S.; Iikura, Y.; Shimizu, H.; Sasano, Y.; Nakane, H.; Sugimoto, N.; Matsui, I.; Takeuchi, N.

1986-01-01

225

A considerable effect of stratospheric aerosol on lidar-detected ozone profile and a three-wavelength inversion technique for both ozone and aerosol  

NASA Technical Reports Server (NTRS)

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 wavelengths of ozone-DIAL are usually considerably different. Usually, an excimer laser of 308nm (on-line) and Raman shifting of 353nm or the third harmonic of a Nd-YAG laser with 355nm (off-line) are selected for measurements of the stratospheric ozone, and there is a difference of 45nm or 47nm between them. Because of the difference there is a difference in the atmospheric scatterings of the two wavelengths. This can cause some error in the retrieved ozone profile if the aerosol scattering is neglected. This paper is devoted to a study of the effect of the stratospheric aerosol on the ozone solution, and a three-wavelength detection technique is proposed for obtaining the more exact ozone profile and the aerosol profile in the stratosphere.

Qiu, Jinhuan

1992-01-01

226

Rayleigh/Raman Greenland lidar observations of atmospheric temperature during a major Arctic stratospheric warming event  

NASA Technical Reports Server (NTRS)

Between Jan. 22 1991 to Feb. 5 1991, we made numerous observations of atmospheric temperature profiles between 10 and 70 km by using the combination of Rayleigh and Raman lidar systems contained in the PL Mobile Lidar Facility located at the National Science Foundation Incoherent Radar Facility of Sondrestrom in Greenland. The purpose of these measurements was to observe the dynamics of the winter Arctic stratosphere and mesosphere regions during a winter period from the succession of temperature profiles obtained in our campaign observations. Various aspects of this investigation are presented.

Meriwether, John W.; Farley, Robert; Mcnutt, R.; Dao, Phan D.; Moskowitz, Warren P.

1992-01-01

227

Raman Lidar Water Vapor Measurements at the DOE SGP CART Site  

NASA Technical Reports Server (NTRS)

The NASA/GSFC Scanning Raman Lidar (SRL) was deployed to the Department of Energy's (DOE) Cloud and Radiation Testbed site in northern Oklahoma September - December, 2000 for two DOE sponsored field campaigns: 1) the Water Vapor Intensive Operations Experiment 2000 and 2) the Atmospheric Radiations Measurement First International Satellite Cloud Climatology Experiment Experiment (AFWEX). WvIOP2000 focussed on water vapor measurements in the lower troposphere while AFWEX focussed on upper tropospheric water vapor. For the first time ever, four water vapor lidars were operated simultaneously: one airborne and three ground-based systems. Intercomparisons of these measurements and others will be presented at the meeting.

Whiteman, David N.; Smith, David E. (Technical Monitor)

2001-01-01

228

Aerosol monitoring in the PBL over big cities using a mobile eye safe LIDAR  

NASA Astrophysics Data System (ADS)

The Laboratory of Science of Climate and Environment (CEA/ CNRS) and LEOSPHERE Company have jointly developed an eye safe, rugged and unattended high resolution scanning lidar ("easy lidar", www.lidar.fr). This system has been used in the frame of the POVA program and has been used in a compact version during the LISAIR (LIdar to Survey the AIR) program in May 2005 in the Paris city, France. The mobile lidar has been used to follow aerosol particles in highways subject to heavy traffic. High spatial and temporal resolution data on the entire planetary boundary layer (1.5 m and 1s respectively) allowed to monitor for aerosol load variability on board a moving car and also to detect for local sources. We observed the doubling of the optical thickness in the morning when traffic is high in the city ring. We also have shown local effect of waste burning plants and train stations. This new type of eye safe lidar will allow to monitor continuously the entire area of a town and suburbs, in order to detect main sources of pollution (transport, traffic jams, industrial plants, natural dust), follow in real time the evolution of the PBL height and provide an estimation of the mass concentration of the aerosol in the PBL.

Sauvage, Laurent; Chazette, Patrick

2005-10-01

229

Intercomparison of lidar and ceilometer retrievals for PBL and aerosol profiling over Athens, Greece  

NASA Astrophysics Data System (ADS)

This paper presents an intercomparison of two active remote sensors (lidar and ceilometer) in determining the structure of the Planetary Boundary Layer (PBL) and atmospheric aerosol vertical profiles, in the troposphere over Athens, Greece. This intercomparison is performed during a 2-day period of coincident and co-located lidar/ceilometer measurements to monitor the temporal evolution of the PBL structure. The portable lidar was provided by Raymetrics S.A. (Greece) and the ceilometer by Vaisala (Finland). Based on a 2AP positioner from Kipp & Zonen B.V. (Holland) Raymetrics S.A. Greece has developed a fully automated 3D scanning eye safe lidar system equipped with a 200 mm diameter telescope (LB11 ESS D-200 model) which can work 24-hours per day, outdoor, under unattended operation under almost any weather condition. Vaisala CL 31 operates at 910 nm and its measurements range goes up to 7.5 km. The methodology followed was based on the determination of the mixing layer height using suspended aerosols as indicator of the PBL structure, in conjunction with available radiosonde data. The limitations of each instrument are also examined. The capability of Vaisala CL31 ceilometer to detect aerosol structures in the free troposphere is additionally evaluated against quality assured lidar profiles. The variability of the aerosol backscatter profile at 355 nm taken with lidar found to be in a good agreement with the ceilometer retrievals, in altitudes higher than 2000 m. That fact indicates that despite its low energy laser and simplicity in transmitter and receiver optical design, a ceilometer can provide qualitative description of the vertical aerosol structures, under the assumption of suitable aerosol loads. The quantitative performance of a ceilometer in regard to the accuracy of the calculated backscatter profiles is finally examined and the improvements on the retrievals are shown when coincident sunphotometric measurements are available.

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

2009-09-01

230

Use of a spectroscopic lidar for standoff explosives detection through Raman spectra  

NASA Astrophysics Data System (ADS)

This paper assesses the potential of detecting explosives (RDX, TNT, PETN, HMX, HMTD, Urea Nitrate) from a distance with a spectroscopic lidar system. For the study, the temporal and spectral resolutions of laser induced fluorescence lidar prototypes were enhanced. The integrated breadboards used easily available Nd:YAG laser wavelengths (266 nm, 355 nm, and 532 nm) to remotely detect the Raman signatures induced in traces of explosives deposited on surfaces. The spectroscopic lidar setup allows for time resolved measurements with high temporal resolution. Raman spectra are observable, even in the presence of fluorescence. Experiments with low average laser power (tens of mWs) have shown the unambiguous capability to detect and identify explosives at distances ranging up to 20 m. Thanks to the combination of UV wavelength for higher Raman cross-sections and efficient gated detection the 355 nm prototype yielded the best compromise. Excitation at 266 nm was expected to yield a better Raman response and was investigated. Less than optimal laser parameters, detection efficiency and strong fluorescence reduced the signal to noise ratio of the 266 nm signals with respect to those at 355 nm and 532 nm showing the importance of optimizing system parameters for high sensitivity detection. Besides the description of the prototypes and an early assessment of their performances, recommendations are also proposed to improve the instrument, leading to an efficient remote sensor for explosives.

Forest, Rosalie; Babin, François; Gay, David; Hô, Nicolas; Pancrati, Ovidiu; Deblois, Simon; Désilets, Sylvain; Maheux, Jean

2012-05-01

231

Study and mitigation of calibration error sources in a water vapour Raman lidar  

NASA Astrophysics Data System (ADS)

The monitoring of water vapour throughout the atmosphere is important for many scientific applications (weather forecasting, climate research, calibration of GNSS altimetry measurements). Measuring water vapour remains a technical challenge because of its high variability in space and time. The major issues are achieving long-term stability (e.g., for climate trends monitoring) and high accuracy (e.g. for calibration/validation applications). LAREG and LOEMI at Institut National de l'Information Géographique et Forestière (IGN) have developed a mobile scanning water vapour Raman lidar in collaboration with LATMOS at CNRS. This system aims at providing high accuracy water vapour measurements throughout the troposphere for calibrating GNSS wet delay signals and thus improving vertical positioning. Current developments aim at improving the calibration method and long term stability of the system to allow the Raman lidar to be used as a reference instrument. The IGN-LATMOS lidar was deployed in the DEMEVAP (Development of Methodologies for Water Vapour Measurement) campaign that took place in 2011 at the Observatoire de Haute Provence. The goals of DEMEVAP were to inter-compare different water vapour sounding techniques (lidars, operational and research radiosondes, GPS,…) and to study various calibration methods for the Raman lidar. A significant decrease of the signals and of the calibration constants of the IGN-LATMOS Raman lidar has been noticed all along the campaign. This led us to study the likely sources of uncertainty and drifts in each part of the instrument: emission, reception and detection. We inventoried several error sources as well as instability sources. The impact of the temperature dependence of the Raman lines on the filter transmission or the fluorescence in the fibre, are examples of the error sources. We investigated each error source and each instability source (uncontrolled laser beam jitter, temporal fluctuations of the photomultiplier gain and spatial inhomogeneity in the sensitivity of the photomultiplier photocathode,…) separately using theoretical analysis, numerical and optical simulations, and laboratory experiments. The instability induced by the use of an optics fibre for coupling the signal collected by the telescope to the detectors is especially investigated. We quantified the impact of all these error sources on the water vapour and nitrogen Raman channels measurements and on the change in the differential calibration constant and we tried to implement an experimental solution to minimize the variations.

David, Leslie; Bock, Olivier; Bosser, Pierre; Thom, Christian; Pelon, Jacques

2014-05-01

232

Remote sensing of the atmosphere by resonance Raman LIDAR  

SciTech Connect

When in resonance, Raman scattering exhibits strong enhancement ranging from four to six orders of magnitude. This physical phenomenon has been applied to remote sensing of the Earth`s atmosphere. With a 16 inch Cassegrain telescope and spectrometer/ CCD-detector system, 70-150 ppm-m of SO{sub 2} in the atmosphere has been detected at a distance of 0.5 kilometer. This system can be used to detect/monitor chemical effluence in the atmosphere by their unique Raman fingerprints. Experimental result together with detailed resonance Raman and atmospheric laser propagation effects will be discussed.

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

1994-12-01

233

Rotational Raman lidar with a multispectral detector for temperature profiling in the atmospheric boundary layer  

NASA Astrophysics Data System (ADS)

Temperature profiling in the atmospheric boundary layer is essential for studying atmospheric processes such as dynamics, thermodynamics, and cloud physics. The rotational Raman (RR) lidar has the ability to conduct continuous observation of the spatial distributions of atmospheric temperature. In this study, a combination of the temperature lidar with a multispectral detector is proposed, in order to construct a system that is compact, robust, and easy to align for the detection of RR signals. The multispectral detector enables simultaneous acquisition of multi-channel photon counts and provides spectral and range-resolved data by applying lidar techniques. Conventional temperature lidar detects the ratio of two RR lidar signals of opposite temperature dependence in combination with several edge- and interference-filters. Conversely, the multispectral detector can define the shape of the RR spectrum. Therefore, the proposed system with a multispectral detector detects the variation of the lidar signals by temperature as well as that of the wavelength shift of the emitted laser. It is suggested that this technique can reduce uncertainties in the optical alignment of the polychromator and in the stability of laser wavelength. The statistical temperature-error derived from the proposed method depends on both the spectral resolution and the spectral range of the multispectral detector. The ideal settings for multispectral observation were estimated by the theoretical simulation of the effect of both spectral resolution and spectral range on the accuracy of temperature estimation. Further, we construct the temperature lidar by employing the multispectral detector with the ideal spectral resolution derived from the simulation. In this presentation, we introduce our proposed system and the preliminary results of the temperature observation from RR lidar with a multi spectral detector.

Yoshikawa, K.; Yabuki, M.; Tsuda, T.

2013-12-01

234

Orbiting lidar simulations. I - Aerosol and cloud measurements by an independent-wavelength technique  

NASA Technical Reports Server (NTRS)

Aerosol and cloud measurements have been simulated for a Space Shuttle lidar. Expected errors - in signal, transmission, density, and calibration - are calculated algebraically and checked by simulating measurements and retrievals using random-number generators. By day, vertical structure is retrieved for tenuous clouds, Saharan aerosols, and boundary layer aerosols (at 0.53 and 1.06 micron) as well as strong volcanic stratospheric aerosols (at 0.53 micron). By night, all these constituents are retrieved plus upper tropospheric and stratospheric aerosols (at 1.06 micron), mesospheric aerosols (at 0.53 micron), and noctilucent clouds (at 1.06 and 0.53 micron). The vertical resolution was 0.1-0.5 km in the troposphere, 0.5-2.0 km above, except 0.25-1.0 km in the mesospheric cloud and aerosol layers; horizontal resolution was 100-2000 km.

Russell, P. B.; Morley, B. M.; Livingston, J. M.; Grams, G. W.; Patterson, E. M.

1982-01-01

235

AROTEL - An Airborne Ozone, Aerosol and Temperature Lidar  

NASA Technical Reports Server (NTRS)

The AROTEL instrument is a collaboration between scientists at NASA, Goddard Space Flight Center and NASA Langley Research Center. The instrument was designed and constructed to be flown on the NASA DC-8, and to measure vertical profiles of ozone, temperature and aerosol. The instrument transmits radiation at 308, 355, 532, and 1064 nm. Depolarization is measured at 532 nm. In addition to the transmitted wavelengths, Raman scattered signals at 332 nm and 387 nm are also collected. The instrument was installed aboard the DC-8 for the SAGE III Ozone Loss and Validation Experiment (SOLVE) which deployed from Kiruna, Sweden, during the winter of 1999-2000 to study the polar stratosphere. During this time, profile measurements of polar stratospheric clouds, ozone and temperature were made. This paper provides an instrumental overview as an introduction to several data papers to be presented in the poster sessions. In addition to samples of the measurements, examples will be given to establish the quality of the various data products.

McGee, Thomas J.; Burris, John F.; Hoegy, Walter; Heaps, William; Silbert, Donald; Twigg, Laurence; Sumnicht, Grant; Nueber, Roland; Schmidt, Thomas; Hostetler, Chris

2000-01-01

236

Development and applications of tunable, narrow band lasers and stimulated Raman scattering devices for atmospheric lidar  

NASA Technical Reports Server (NTRS)

The main thrust of the program was the study of stimulated Raman processes for application to atmospheric lidar measurements. This has involved the development of tunable lasers, the detailed study of stimulated Raman scattering, and the use of the Raman-shifted light for new measurements of molecular line strengths and line widths. The principal spectral region explored in this work was the visible and near-IR wavelengths between 500 nm and 1.5 microns. Recent alexandrite ring laser experiments are reported. The experiments involved diode injection-locking, Raman shifting, and frequency-doubling. The experiments succeeded in producing tunable light at 577 and 937 nm with line widths in the range 80-160 MHz.

Wilkerson, Thomas D.

1993-01-01

237

Lidar Measurements from Space of Aerosol Distribution and Optical Depth over Oceans for 2003 - 2004  

Microsoft Academic Search

Space borne lidar observations of global clouds and aerosol from polar orbit were acquired by the Geoscience Laser Altimeter System beginning in 2003. The measurements in Oct. Nov. 2003 and Feb. March 2004 include highly sensitive aerosol detection and profiling by photon counting detection at 532 nm wavelength to backscatter cross section below 10-7 1\\/m-sr. Data products from the measurements

J. D. Spinhirne; E. M. Welton; S. P. Palm; D. L. Hlavka; W. D. Hart

2006-01-01

238

Aerosol and Cloud Interaction Observed From High Spectral Resolution Lidar Data  

NASA Technical Reports Server (NTRS)

Recent studies utilizing satellite retrievals have shown a strong correlation between aerosol optical depth (AOD) and cloud cover. However, these retrievals from passive sensors are subject to many limitations, including cloud adjacency (or 3D) effects, possible cloud contamination, uncertainty in the AOD retrieval. Some of these limitations do not exist in High Spectral Resolution Lidar (HSRL) observations; for instance, HSRL observations are not a ected by cloud adjacency effects, are less prone to cloud contamination, and offer accurate aerosol property measurements (backscatter coefficient, extinction coefficient, lidar ratio, backscatter Angstrom exponent,and aerosol optical depth) at a neospatial resolution (less than 100 m) in the vicinity of clouds. Hence, the HSRL provides an important dataset for studying aerosol and cloud interaction. In this study, we statistically analyze aircraft-based HSRL profiles according to their distance from the nearest cloud, assuring that all profile comparisons are subject to the same large-scale meteorological conditions. Our results indicate that AODs from HSRL are about 17% higher in the proximity of clouds (approximately 100 m) than far away from clouds (4.5 km), which is much smaller than the reported cloud 3D effect on AOD retrievals. The backscatter and extinction coefficients also systematically increase in the vicinity of clouds, which can be explained by aerosol swelling in the high relative humidity (RH) environment and/or aerosol growth through in cloud processing (albeit not conclusively). On the other hand, we do not observe a systematic trend in lidar ratio; we hypothesize that this is caused by the opposite effects of aerosol swelling and aerosol in-cloud processing on the lidar ratio. Finally, the observed backscatter Angstrom exponent (BAE) does not show a consistent trend because of the complicated relationship between BAE and RH. We demonstrate that BAE should not be used as a surrogate for Angstrom exponent, especially at high RH.

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

2008-01-01

239

Measurement of aerosol profiles using high-spectral-resolution Rayleigh-Mie lidar  

NASA Technical Reports Server (NTRS)

High-spectral-resolution Rayleigh-Mie lidar measurements of vertical profiles (1 to 5 km) of atmospheric pressure and density, as well as aerosol profiles, including backscatter ratio and extinction ratio are reported. These require simultaneous measurement of temperature. Use of the technique does not require any assumptions about the aerosol but does require that the pressure at one altitude is known and that the gas law of the air is known (e.g., an ideal gas).

Krueger, D. A.; Alvarez, R. J., II; Caldwell, L. M.; She, C. Y.

1992-01-01

240

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

NASA Technical Reports Server (NTRS)

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

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

1991-01-01

241

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

242

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

PubMed

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

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

2012-08-01

243

Aerosol and Cloud Observations and Data Products by the GLAS Polar Orbiting Lidar Instrument  

NASA Technical Reports Server (NTRS)

The Geoscience Laser Altimeter System (GLAS) launched in 2003 is the first polar orbiting satellite lidar. The instrument was designed for high performance observations of the distribution and optical scattering cross sections of clouds and aerosol. The backscatter lidar operates at two wavelengths, 532 and 1064 nm. Both receiver channels meet and exceed their design goals, and beginning with a two month period through October and November 2003, an excellent global lidar data set now exists. The data products for atmospheric observations include the calibrated, attenuated backscatter cross section for cloud and aerosol; height detection for multiple cloud layers; planetary boundary layer height; cirrus and aerosol optical depth and the height distribution of aerosol and cloud scattering cross section profiles. The data sets are now in open release through the NASA data distribution system. The initial results on global statistics for cloud and aerosol distribution has been produced and in some cases compared to other satellite observations. The sensitivity of the cloud measurements is such that the 70% global cloud coverage result should be the most accurate to date. Results on the global distribution of aerosol are the first that produce the true height distribution for model inter-comparison.

Spinhirne, J. D.; Palm, S. P.; Hlavka, D. L.; Hart, W. D.; Mahesh, A.; Welton, E. J.

2005-01-01

244

Vertical distribution of aerosols over the east coast of India inferred from airborne LIDAR measurements  

NASA Astrophysics Data System (ADS)

The information on altitude distribution of aerosols in the atmosphere is essential in assessing the impact of aerosol warming on thermal structure and stability of the atmosphere. In addition, aerosol altitude distribution is needed to address complex problems such as the radiative interaction of aerosols in the presence of clouds. With this objective, an extensive, multi-institutional and multi-platform field experiment (ICARB-Integrated Campaign for Aerosols, gases and Radiation Budget) was carried out under the Geosphere Biosphere Programme of the Indian Space Research Organization (ISRO-GBP) over continental India and adjoining oceans during March to May 2006. Here, we present airborne LIDAR measurements carried out over the east Coast of the India during the ICARB field campaign. An increase in aerosol extinction (scattering + absorption) was observed from the surface upwards with a maximum around 2 to 4 km. Aerosol extinction at higher atmospheric layers (>2 km) was two to three times larger compared to that of the surface. A large fraction (75-85%) of aerosol column optical depth was contributed by aerosols located above 1 km. The aerosol layer heights (defined in this paper as the height at which the gradient in extinction coefficient changes sign) showed a gradual decrease with an increase in the offshore distance. A large fraction (60-75%) of aerosol was found located above clouds indicating enhanced aerosol absorption above clouds. Our study implies that a detailed statistical evaluation of the temporal frequency and spatial extent of elevated aerosol layers is necessary to assess their significance to the climate. This is feasible using data from space-borne lidars such as CALIPSO, which fly in formation with other satellites like MODIS AQUA and MISR, as part of the A-Train constellation.

Satheesh, S. K.; Vinoj, V.; Babu, S. Suresh; Krishna Moorthy, K.; Nair, Vijayakumar S.

2009-11-01

245

A comparison between Raman lidar and conventional contact measurements of atmospheric temperature  

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

246

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

NASA Technical Reports Server (NTRS)

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

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

2002-01-01

247

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

Microsoft Academic Search

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

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

2009-01-01

248

The 48-inch lidar aerosol measurements taken at the Langley Research Center  

NASA Technical Reports Server (NTRS)

This report presents lidar data taken between July 1991 and December 1992 using a ground-based 48-inch lidar instrument at the Langley Research Center in Hampton, Virginia. Seventy lidar profiles (approximately one per week) were obtained during this period, which began less than 1 month after the eruption of the Mount Pinatubo volcano in the Philippines. Plots of backscattering ratio as a function of altitude are presented for each data set along with tables containing numerical values of the backscattering ratio and backscattering coefficient versus altitude. The enhanced aerosol backscattering seen in the profiles highlights the influence of the Mount Pinatubo eruption on the stratospheric aerosol loading over Hampton. The long-term record of the profiles gives a picture of the evolution of the aerosol cloud, which reached maximum loading approximately 8 months after the eruption and then started to decrease gradually. NASA RP-1209 discusses 48-inch lidar aerosol measurements taken at the Langley Research Center from May 1974 to December 1987.

Woods, David C.; Osborn, M. T.; Winker, D. M.; Decoursey, R. J.; Youngbluth, Otto, Jr.

1994-01-01

249

Aerosol Transport Questions Arising From Micro Pulse Lidar Measurements During MILAGRO  

Microsoft Academic Search

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

R. Kotamarthi; R. Coulter; M. Pekour

2007-01-01

250

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

251

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

NASA Technical Reports Server (NTRS)

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

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

1997-01-01

252

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

NASA Technical Reports Server (NTRS)

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

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

1993-01-01

253

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

254

A new constituting lidar network for global aerosol observation and monitoring: Leone  

NASA Astrophysics Data System (ADS)

In order to observe and monitoring the direct and indirect impact of natural and anthropogenic aerosols on the radiative transfer and climate changing, it is necessary a continuous worldwide observation of the microphysical aerosol properties. A global observation it is of great support to the actual research in climate and it is a complement in the effort of monitoring trans-boundary pollution, and satellite validation, valorizing the use of lidar and passive sensors networks. In this framework, we have created the LEONET program, a new constituting worldwide network of EZ Lidar™ instruments. These lidars, developed by the French company LEOSPHERE, are compact and rugged eye safe UV Lidars with cross-polarisation detection capabilities, designed to monitor and study the atmospheric vertical structure of aerosols and clouds in a continuous way, night and day, over long time period in order to investigate and contribute to the climate change studies. LEONET output data, in hdf format, have the same architecture of those of NASA Micro Pulse Lidar Network (MPLNET) and will be soon available to the scientific community through the AERONET data synergy tool which provides ground-based, satellite, and model data products to characterize aerosol optical and microphysical properties, spatial and temporal distribution, transport, and chemical and radiative properties. In this work, it is presented an overview of the LEONET products and methodologies as the backscattering and extinction coefficients; the depolarization ratio, cloud layer heights and subsequent optical depths, provided to the limit of detection capability from a range of 100 m up to 20 km as well as the recent automatic height retrieval method of the different Planetary Boundary Layers (PBL). The retrieval algorithm in the future will be improved integrating, when possible, a measured Lidar ratio by a co-located sun photometer Further are presented some data examples from several diverse sites in the network.

Lolli, Simone; Sauvage Laurent, Laurent

2010-05-01

255

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

Microsoft Academic Search

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

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

2010-01-01

256

Estimation of Direct Radiative Forcing of Asian Dust Aerosols with Sun\\/Sky Radiometer and Lidar Measurements at Gosan, Korea  

Microsoft Academic Search

In this study the aerosol direct radiative forcing (ADRF) of Asian dust is evaluated by model simulation at Gosan, Jeju using the data from a sun\\/sky radiometer, a Micro-Pulse Lidar (MPL), and column radiometer measurements of solar downwelling irradiance in April, 2001. We suggest a method of determining aerosol parameters for the radiative transfer model from the Aerosol Robotic Network

Jae-Gwang WON; Soon-Chang YOON; Sang-Woo KIM; Ann JEFFERSON; Ellsworth G. DUTTON; Brent N. HOLBEN

2004-01-01

257

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

NASA Technical Reports Server (NTRS)

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

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

2012-01-01

258

LIDAR Measurements of Tropospheric Aerosols and Boundary Layers  

Microsoft Academic Search

Tropospheric aerosols have effects on climate directly through sun light attenuation as well as indirectly due to their influence on cloud formation. The knowledge of aerosol variation is crucial to consider their effects on the radiation of the atmosphere. Due to different radiative conditions (day and night, high surface albedo) the aerosols may have a strong influence on the radiative

M. A. Gondal; L. Lelli; K. Stalmaszczyk; S. Frey; L. Woeste

2004-01-01

259

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

NASA Technical Reports Server (NTRS)

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

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

2002-01-01

260

Gas dispersion measurements using a mobile Raman lidar system  

NASA Technical Reports Server (NTRS)

The exploitation of natural gas resources to supply energy demands has resulted in the need to engineer pipelines and plants capable of handling extremely high pressures and throughputs. Consequently, more attention has been directed to evaluating the consequences of releases of material whether accidental or deliberate in nature. An important aspect of assessing the consequences of a release is an understanding of how gas disperses in the atmosphere over a wide range of release and atmospheric conditions. The most cost effective way of providing such information is through the development and use of reliable theoretical prediction methods. The need for some form of remote sensing device was identified. The various possibilities studied led to the conclusion that LIDAR (Light Detection And Ranging) offered the most suitable method. The system designed and built is described, and its recent use in monitoring operational ventings from a high pressure transmission system is discussed.

Houston, J. D.; Brown, D. R.

1986-01-01

261

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

262

Parametric study of an excimer-pumped, nitrogen Raman shifter for lidar applications  

SciTech Connect

A krypton fluoride (KrF) excimer-pumped, nitrogen Raman shifter has been studied for use in a wavelength-optimized solar-blind Raman lidar. First Stokes conversion efficiencies (248 {r_arrow} 263 nm) as high as 12% have been observed in N{sub 2}:He gas mixtures. Both oscillator--amplifier and self-seeded configurations were investigated. Wavelength-dependent effects were investigated with a Nd:YAG laser operating at 532 and 266 nm. A comparison of KrF- and Nd:YAG-pumped Raman shifting has shown that the beam quality of the excimer laser was a major factor in limiting the maximum first Stokes conversion efficiency.

Bisson, S.E. [Diagnostics Research Division, Sandia National Laboratories, Livermore, California 94551-0969 (United States)

1995-06-20

263

Validation of aerosol and cloud layer structures from the space-borne lidar CALIOP using Seoul National University ground-based lidar  

NASA Astrophysics Data System (ADS)

We present first observationally based validations of the space-borne lidar CALIOP onboard CALIPSO satellite using coincidental observations from a ground-based SNU lidar for 3 different types of atmospheric scenes. Both lidar measurements were taken in nearly same airmass in space and time. Total attenuated backscatters at 532 nm from the two instruments show similar aerosol and cloud layer structures (the top and bottom heights) both under cloud-free conditions and in case of multi-aerosol layers underlying semi-transparent cirrus clouds. This result confirms that the CALIPSO science team algorithms of the discrimination of cloud and aerosol as well as of their layer top and base altitudes are sound. Under thick clouds conditions, only information on the cloud top (bottom) height is reliable from CALIOP (ground-based lidar) observations due to strong signal attenuations. However, simultaneous space-borne CALIOP and ground-based SNU lidar measurements complement each other and provide full information on the vertical distribution of aerosols and clouds. Discrepancies between space-borne and ground-based lidar signals are partly explained by the strong spatial and vertical inhomogeneous distributions of clouds at few kilometer horizontal scales.

Kim, S.-W.; Berthier, S.; Chazette, P.; Raut, J.-C.; Dulac, F.; Yoon, S.-C.

2007-08-01

264

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

NASA Technical Reports Server (NTRS)

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

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

1999-01-01

265

Multi-year investigations of aerosol layer using lidar measurements at Chung-Li, Taiwan  

NASA Astrophysics Data System (ADS)

Height, evolution and structure of the nocturnal aerosol layers in the lower troposphere is reported by using a ground-based lidar over Chung-Li (24.58N,121.10E), Taiwan, during the period from March 2002 to December 2008. Investigation shows that the aerosol layers mainly distributed at an altitude range between 0.2 and 3 km. The mean height and depth of the aerosol layer are 0.57±0.11 km and 0.63±0.14 km, respectively. Seasonality is observed for the depth and height of the aerosol layer. The wind shear and temperature inversion is calculated from the radiosonde data. The statistical interpretation shows a correlation between lidar-derived aerosol layer height and wind shear and also with the temperature inversion. The depth and height of aerosol layer have a positive correlation with Bulk Richardson number. The seasonal features of tropospheric aerosols and their impact on the PM10 mass concentrations are also examined.

Chiang, Chih-Wei; Kumar Das, Subrata; Lin, Chuan-Yao; Nee, Jan B.; Sun, Shu-Huang; Chiang, Hung-Wei; Yu, Ming-Ju; Shu-Ting, Zhang

2012-11-01

266

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

NASA Technical Reports Server (NTRS)

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

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

2000-01-01

267

Raman Lidar Measurements of Water Vapor and Cirrus Clouds During the Passage of Hurricane Bonnie  

NASA Technical Reports Server (NTRS)

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 focussed 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 (Scanning Raman Lidar) and other sensors. Cirrus cloud optical depths (at 351 nm) were also measured during this period. Optical depth values ranged from approximately 0.01 to 1.4. The influence of multiple scattering on these optical depth measurements was studied with the conclusion that the measured values of optical depth are less than the actual value by up to 20% . The UV/IR cirrus cloud optical depth ratio was estimated based on a comparison of lidar and GOES 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 approximately 0.02 or greater. This has implications for satellite cirrus detection requirements.

Whiteman, D. N.; Evans, K. D.; Demoz, B.; Starr, D. OC; Tobin, D.; Feltz, W.; Jedlovec, G. J.; Gutman, S. I.; Schwemmer, G. K.; Cardirola, M.; Melfi, S. H.; Schmidlin, F. J.

2000-01-01

268

Aerosol and cloud sensing with the Lidar In-space Technology Experiment (LITE)  

NASA Technical Reports Server (NTRS)

The Lidar In-space Technology Experiment (LITE) is a multi-wavelength backscatter lidar developed by NASA Langley Research Center to fly on the Space Shuttle. The LITE instrument is built around a three-wavelength ND:YAG laser and a 1-meter diameter telescope. The laser operates at 10 Hz and produces about 500 mJ per pulse at 1064 nm and 532 nm, and 150 mJ per pulse at 355 nm. The objective of the LITE program is to develop the engineering processes required for space lidar and to demonstrate applications of space-based lidar to remote sensing of the atmosphere. The LITE instrument was designed to study a wide range of cloud and aerosol phenomena. To this end, a comprehensive program of scientific investigations has been planned for the upcoming mission. Simulations of on-orbit performance show the instrument has sufficient sensitivity to detect even thin cirrus on a single-shot basis. Signal averaging provides the capability of measuring the height and structure of the planetary boundary layer, aerosols in the free troposphere, the stratospheric aerosol layer, and density profiles to an altitude of 40 km. The instrument has successfully completed a ground-test phase and is scheduled to fly on the Space Shuttle Discovery for a 9-day mission in September 1994.

Winker, D. M.; McCormick, M. P.

1994-01-01

269

Urban aerosol spatial variations using a slant-angle scanning Mie lidar system  

NASA Astrophysics Data System (ADS)

An eye-safe, mobile micro-pulse Mie Lidar system has recently been integrated. The system is capable of taking slant angle 360 degree horizontal scans of aerosol distributions, as well as vertical boundary-layer profiles in a zenith pointing position. The Lidar is co-axial, and the transmitter is a high repetition rate, diode-pumped micro-joule pulse energy, Nd:YAG 532 nm laser. The receiver is a compact Schmidt-Cassegrain f/6.3 telescope. The whole system can be fitted into a small van for field observations. The main objective in building this Lidar in Hong Kong is for monitoring spatially varying aerosols and vertical distributions within the lower few km of the troposphere. In this paper, the near range corrections from geometric ray tracing are presented together with field data. Representative spatial scans over urban Hong Kong are also given. The new system will be deployed in the very near future to study the correlation between the spatial distribution of aerosols and local traffic conditions. The Lidar design may represent a typical commercial product of the current technology.

Cheng, Andrew Y. S.; Walton, Andrew; Chan, Johnny C. L.

2003-03-01

270

Lidar observations of stratospheric aerosol layer after the Mt. Pinatubo volcanic eruption  

NASA Technical Reports Server (NTRS)

The volcano Mt. Pinatubo located on the Luzon Island, Philippines, had explosively erupted on June 15, 1991. The volcanic eruptions such as volcanic ash, SO2 and H2O reached into the stratosphere over 30 km altitude by the NOAA-11 satellite observation and this is considered one of the biggest volcanic eruptions in this century. A grandiose volcanic eruption influences the atmosphere seriously and causes many climatic effects globally. There had been many impacts on radiation, atmospheric temperature and stratospheric ozone after some past volcanic eruptions. The main cause of volcanic influence depends on stratospheric aerosol, that stay long enough to change climate and other meteorological conditions. Therefore it is very important to watch stratospheric aerosol layers carefully and continuously. Standing on this respect, we do not only continue stratospheric aerosol observation at Tsukuba but also have urgently developed another lidar observational point at Naha in Okinawa Island. This observational station could be thought valuable since there is no lidar observational station in this latitudinal zone and it is much nearer to Mt. Pinatubo. Especially, there is advantage to link up these two stations on studying the transportation mechanism in the stratosphere. In this paper, we present the results of lidar observations at Tsukuba and Naha by lidar systems with Nd:YAG laser.

Nagai, Tomohiro; Uchino, Osamu; Fujimoto, Toshifumi

1992-01-01

271

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

NASA Technical Reports Server (NTRS)

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

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

2001-01-01

272

AGLITE: a multi-wavelength lidar for measuring emitted aerosol concentrations and fluxes and air motion from agricultural facilities  

Microsoft Academic Search

AGLITE is a multi-wavelength lidar developed for the Agricultural Research Service (ARS), United States Department of Agriculture (USDA) and its program on particle emissions from animal production facilities. The lidar transmitter is a 10 kHz pulsed NdYAG laser at 355, 532 and 1064 nm. We analyze lidar backscatter and extinction to extract aerosol physical properties. All-reflective optics and dichroic and

Thomas D. Wilkerson; Gail E. Bingham; Vladimir V. Zavyalov; Jason A. Swasey; Jed J. Hancock; Blake G. Crowther; Scott S. Cornelsen; Christian Marchant; James N. Cutts; David C. Huish; Curtis L. Earl; Jan M. Andersen; McLain L. Cox

2006-01-01

273

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

274

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

275

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

276

Development of a small portable eyesafe unattended scanning lidar for analysis of the structural and optical properties of tropospheric aerosols  

Microsoft Academic Search

Structural and optical properties of aerosols and clouds can be retrieved by active remote sensing systems, such as lidars. Such parameters are of importance in the study of dynamics and radiation budget of the atmosphere. In that respect, a small, portable, eyesafe, unattended, elastic-backscatter lidar is being developed at Cimel Electronique, in collaboration with CNRS. It sues a compact, low-energy

Michael Sicard; Jacques R. Pelon; Jean P. Buis; Patrick Chazette

2001-01-01

277

A lidar system for remote sensing of aerosols and water vapor from NSTS and Space Station Freedom  

NASA Technical Reports Server (NTRS)

The Tropical Atmospheric Lidar Observing System (TALOS) is proposed to be developed as a Differential Absorption Lidar (DIAL) system for flight aboard the earth orbiting Space Station Freedom. TALOS will be capable of making high resolution vertical profile measurements of tropospheric water and tropospheric and stratospheric aerosols, clouds and temperature.

Delorme, Joseph F.

1989-01-01

278

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.

279

Aerosol Backscatter from Airborne Continuous Wave CO2 Lidars Over Western North America and the Pacific Ocean  

NASA Technical Reports Server (NTRS)

Atmospheric aerosol backscatter, beta, variability gives a direct indication of aerosol loading. Since aerosol variability is governed by regional sources and sinks as well as affected by its transport due to meteorological conditions, it is important to characterize this loading at different locations and times. Lidars are sensitive instruments that can effectively provide high-resolution, large-scale sampling of the atmosphere remotely by measuring aerosol beta, thereby capturing detailed temporal and spatial variability of aerosol loading, Although vertical beta profiles are usually obtained by pulsed lidars, airborne-focused CW lidars, with high sensitivity and short time integration, can provide higher resolution sampling in the vertical, thereby revealing detailed structure of aerosol layers. During the 1995 NASA Multicenter Airborne Coherent Atmospheric Wind Sensor (MACAWS) mission, NASA MSFC airborne-focused CW CO2 Doppler lidars, operating at 9.1 and 10.6-micrometers wavelength, obtained high resolution in situ aerosol beta measurements to characterize aerosol variability. The observed variability in beta at 9.1-micrometers wavelength with altitude is presented as well as comparison with some pulsed lidar profiles.

Jarzembski, Maurice A.; Srivastava, Vandana; Rothermel, Jeffry

1999-01-01

280

Daytime Raman lidar measurements of water vapor during the ARM 1997 water vapor intensive observation period  

SciTech Connect

Because of the importance of water vapor, the ARM program initiated a series of three intensive operating periods (IOPs) at its CART (Cloud And Radiation Testbed) site. The goal of these IOPs is to improve and validate the state-of-the-art capabilities in measuring water vapor. To date, two of the planned three IOPs have occurred: the first was in September of 1996, with an emphasis on the lowest kilometer, while the second was conducted from September--October 1997 with a focus on both the upper troposphere and lowest kilometer. These IOPs provided an excellent opportunity to compare measurements from other systems with those made by the CART Raman lidar. This paper addresses primarily the daytime water vapor measurements made by the lidar system during the second of these IOPs.

Turner, D.D. [Pacific Northwest National Lab., Richland, WA (United States); Goldsmith, J.E.M. [Sandia National Labs., Livermore, CA (United States)

1998-04-01

281

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

NASA Astrophysics Data System (ADS)

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

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

2010-04-01

282

Intercomparison of Pulsed Lidar Data with Flight Level CW Lidar Data and Modeled Backscatter from Measured Aerosol Microphysics Near Japan and Hawaii  

NASA Technical Reports Server (NTRS)

Aerosol backscatter coefficient data were examined from two nights near Japan and Hawaii undertaken during NASA's Global Backscatter Experiment (GLOBE) in May-June 1990. During each of these two nights the aircraft traversed different altitudes within a region of the atmosphere defined by the same set of latitude and longitude coordinates. This provided an ideal opportunity to allow flight level focused continuous wave (CW) lidar backscatter measured at 9.11-micron wavelength and modeled aerosol backscatter from two aerosol optical counters to be compared with pulsed lidar aerosol backscatter data at 1.06- and 9.25-micron wavelengths. The best agreement between all sensors was found in the altitude region below 7 km, where backscatter values were moderately high at all three wavelengths. Above this altitude the pulsed lidar backscatter data at 1.06- and 9.25-micron wavelengths were higher than the flight level data obtained from the CW lidar or derived from the optical counters, suggesting sample volume effects were responsible for this. Aerosol microphysics analysis of data near Japan revealed a strong sea-salt aerosol plume extending upward from the marine boundary layer. On the basis of sample volume differences, it was found that large particles were of different composition compared with the small particles for low backscatter conditions.

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

1998-01-01

283

Performance of the GLAS Satellite Lidar Cloud and Aerosol Measurements  

Microsoft Academic Search

Launched in early 2003, the geoscience laser altimeter system (GLAS) on the Ice, Cloud and Land Elevation Satellite is the first polar orbiting satellite lidar and is intended for comprehensive earth science applications covering surface altimetry for ice sheets and vegetation and atmospheric profiling. The instrument design includes high performance observations of the distribution and optical scattering cross sections of

James D. Spinhirne

2008-01-01

284

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

285

Doppler Rayleigh\\/Mie\\/Raman lidar for wind and temperature measurements in the middle atmosphere up to 80 km  

Microsoft Academic Search

A direct detection Doppler lidar for measuring wind speed in the middle atmosphere up to 80 km with 2 h resolution was implemented in the ALOMAR Rayleigh\\/Mie\\/Raman lidar (69° N, 16° E). The random error of the line of sight wind is about 0.6 m\\/s and 10 m\\/s at 49 km and 80 km, respectively. We use a Doppler Rayleigh

G. Baumgarten

2010-01-01

286

Tropospheric Aerosol Study by Fly's Eye and LIDAR Technique  

Microsoft Academic Search

The Fly's Eye is an experiment to study high energy cosmic ray air showers. It has been in operation for more than a decade. However, how the tropospheric aerosol impacts on the Fly's Eye cosmic ray research and the manner in which the Fly's Eye can contribute to atmospheric aerosol research are still subjects that require further study. In this

Steven Mengzhi Luo

1992-01-01

287

Lidar and in situ observations of continental and Saharan aerosol: closure analysis of particles optical and physical properties  

NASA Astrophysics Data System (ADS)

Single wavelength polarization lidar observations collected at Mt. Cimone (44.2º N, 10.7º E, 1870 m a.s.l.) during the June 2000 MINATROC campaign are analyzed to derive tropospheric profiles of aerosol extinction, depolarization, surface area and volume. Lidar retrievals for the 2170-2245 m level are compared to the same variables as computed from in situ measurements of particles size distributions, performed at the mountain top Station (2165 m a.s.l.) by a differential mobility analyzer (DMA) and an optical particle counter (OPC). A sensitivity analysis of this closure experiment shows that mean relative differences between the backscatter coefficients obtained by the two techniques undergo a sharp decrease when hygroscopic growth to ambient humidity is considered for the DMA dataset, otherwise representative of dry aerosols. Minimization of differences between lidar and size distribution-derived backscatter coefficients allowed to find values of the "best" refractive index, specific to each measurement. These results show the refractive index to increase for air masses proceeding from Africa and Western Europe. Lidar depolarization was observed to minimize mainly in airmasses proceeding from Western Europe, thus indicating a spherical, i.e. liquid nature for such aerosols. Conversely, African, Mediterranean and East Europe aerosol showed a larger depolarizing fraction, mainly due to coexisting refractory and soluble fractions. The analysis shows average relative differences between lidar and in-situ observations of 5% for backscatter, 36% for extinction 41% for surface area and 37% for volume. These values are well within the expected combined uncertainties of the lidar and in situ retrievals. Average differences further decrease during the Saharan dust transport event, when a lidar signal inversion model considering non-spherical scatterers is employed. The quality of the closure obtained between particle counter and lidar-derived aerosol surface area and volume observations constitutes a validation of the technique adopted to retrieve such aerosol properties on the basis of single-wavelength lidar observations.

Gobbi, G. P.; Barnaba, F.; van Dingenen, R.; Putaud, J. P.; Mircea, M.; Facchini, M. C.

2003-12-01

288

Characterizing Aerosol Distributions and Optical Properties Using the NASA Langley High Spectral Resolution Lidar  

SciTech Connect

The objective of this project was to provide vertically and horizontally resolved data on aerosol optical properties to assess and ultimately improve how models represent these aerosol properties and their impacts on atmospheric radiation. The approach was to deploy the NASA Langley Airborne High Spectral Resolution Lidar (HSRL) and other synergistic remote sensors on DOE Atmospheric Science Research (ASR) sponsored airborne field campaigns and synergistic field campaigns sponsored by other agencies to remotely measure aerosol backscattering, extinction, and optical thickness profiles. Synergistic sensors included a nadir-viewing digital camera for context imagery, and, later in the project, the NASA Goddard Institute for Space Studies (GISS) Research Scanning Polarimeter (RSP). The information from the remote sensing instruments was used to map the horizontal and vertical distribution of aerosol properties and type. The retrieved lidar parameters include profiles of aerosol extinction, backscatter, depolarization, and optical depth. Products produced in subsequent analyses included aerosol mixed layer height, aerosol type, and the partition of aerosol optical depth by type. The lidar products provided vertical context for in situ and remote sensing measurements from other airborne and ground-based platforms employed in the field campaigns and was used to assess the predictions of transport models. Also, the measurements provide a data base for future evaluation of techniques to combine active (lidar) and passive (polarimeter) measurements in advanced retrieval schemes to remotely characterize aerosol microphysical properties. The project was initiated as a 3-year project starting 1 January 2005. It was later awarded continuation funding for another 3 years (i.e., through 31 December 2010) followed by a 1-year no-cost extension (through 31 December 2011). This project supported logistical and flight costs of the NASA sensors on a dedicated aircraft, the subsequent analysis and archival of the data, and the presentation of results in conferences, workshops, and publications. DOE ASR field campaigns supported under this project included - MAX-Mex /MILAGRO (2006) - TexAQS 2006/GoMACCS (2006) - CHAPS (2007) - RACORO (2009) - CARE/CalNex (2010) In addition, data acquired on HSRL airborne field campaigns sponsored by other agencies were used extensively to fulfill the science objectives of this project and the data acquired have been made available to other DOE ASR investigators upon request.

Hostetler, Chris; Ferrare, Richard

2013-02-14

289

Water vapor measurements by Raman lidar during the ARM 1997 water vapor intensive observation period  

SciTech Connect

Water vapor is the most important greenhouse gas in the atmosphere, as it is the most active infrared absorber and emitter of radiation, and it also plays an important role in energy transport and cloud formation. Accurate, high resolution measurements of this variable are critical in order to improve the understanding of these processes and thus their ability to model them. Because of the importance of water vapor, the Department of Energy`s Atmospheric Radiation Measurement (ARM) program initiated a series of three intensive operating periods (IOPs) at its Cloud and Radiation Testbed (CART) site in northern Oklahoma. The goal of these IOPs is to improve and validate the state-of-the-art capabilities in measuring water vapor. To date, two of the planned three IOPs have occurred: the first was in September of 1996, with an emphasis on the lowest kilometer, while the second was conducted from September--October 1997 with a focus on both the upper troposphere and lowest kilometer. The ARM CART site is the home of several different water vapor measurement systems. These systems include a Raman lidar, a microwave radiometer, a radiosonde launch site, and an instrumented tower. During these IOPs, additional instrumentation was brought to the site to augment the normal measurements in the attempt to characterize the CART instruments and to address the need to improve water vapor measurement capabilities. Some of the instruments brought to the CART site include a scanning Raman lidar system from NASA/GSFC, additional microwave radiometers from NOAA/ETL, a chilled mirror that was flown on a tethersonde and kite system, and dewpoint hygrometer instruments flow on the North Dakota Citation. This paper will focus on the Raman lidar intercomparisons from the second IOP.

Turner, D.D. [Pacific Northwest National Lab., Richland, WA (United States); Whiteman, D.N.; Schwemmer, G.K. [National Aeronautics and Space Administration, Greenbelt, MD (United States). Goddard Space Flight Center; Evans, K.D. [Univ. of Maryland, Baltimore, MD (United States)]|[National Aeronautics and Space Administration, Greenbelt, MD (United States). Goddard Space Flight Center; Melfi, S.H. [Univ. of Maryland, Baltimore, MD (United States); Goldsmith, J.E. [Sandia National Labs., Livermore, CA (United States)

1998-04-01

290

Measurements of daytime and upper tropospheric water vapor profiles by Raman lidar  

SciTech Connect

One of the most important atmospheric constituents needed for climate and meteorological studies is water vapor. Water vapor plays an important role in driving atmospheric circulations through latent heat release and in determining the earth`s radiation budget, both through its radiative effects (water vapor is the major greenhouse gas) and cloud formation. The vertical distribution of water vapor is particularly important because it not only determines convective stability but radiative effects are also strongly altitude dependent. At present, considerable controversy exists over the nature of the vertical redistribution of water vapor in a changing climate, and particularly the distribution of water vapor in the upper troposphere. Understanding upper tropospheric moistening processes such as deep convection are therefore of prime importance in addressing the water vapor feedback question. A powerful, proven technique for the continuous measurement of nighttime water vapor profiles (in clear skies or up to the lowest cloud level) with high spatial and temporal resolution is Raman lidar. As part of the U.S. Department of Energy`s (DOE) Atmospheric Radiation Measurement (ARM) program, a high performance dual field-of-view (fov), narrowband Raman lidar system capable of both daytime and nighttime operation has been developed. In this paper, the Sandia Raman lidar system is discussed along with its application to two problems of current interest: daytime tropospheric water vapor profile measurements and upper tropospheric water vapor. We present recent measurements of upper tropospheric moisture made at the DOE Cloud and Radiation Testbed site (CART) in Oklahoma. Recent daytime measurements are also presented.

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

1995-03-01

291

A lidar study of the spatial and temporal variability of aerosol pollution over New Haven, CT  

NASA Astrophysics Data System (ADS)

Aerosol particles and clouds are key components of the climate system, but their complex interactions and net effects are currently poorly understood. Anthropogenic aerosols, including sulfate, black carbon, nitrate and dust, have been shown to have cooling effects on climate, but the magnitude of this cooling is unclear (IPCC, 2007). Determining how aerosols and clouds are distributed vertically in the atmosphere is crucial for their integration in climate models and also for understanding aerosol effects on air quality. This study evaluates spatial and temporal patterns of aerosol and cloud variability over an urban environment, New Haven, in the summer and fall of 2013. Boundary layer dynamics and aerosol optical depths (AOD) are analyzed based on vertical profiles retrieved with a ground-based lidar that emits pulses of UV light (wavelength 355nm) into the atmosphere. Aerosol optical depth statistics and patterns of aerosol accumulation will be presented. Mean daily aerosol optical depth from June-July 2013 was 0.268, with a peak daily mean of 0.495. Aerosol spatial distributions are found to depend on meteorological conditions, but three characteristic regimes were observed and will be described: one of diurnal peaks in particle loading, one of midday lifting of aerosols accumulated in the boundary layer, and one marked by the presence of lofted, nonlocal aerosols. The study identifies high-pollution events for further study based on rapid increases in AOD, such as from a mean value of 0.225 to 0.393 on consecutive days July 8-9. The origins of polluted, nonlocal air parcels, which are often lofted and distinct from an underlying boundary layer, will be discussed based on data from local weather stations. The present study characterizes the typical aerosol concentrations and distributions over New Haven in summer and fall, enhancing our understanding of urban atmospheric impacts.

Smyth, J. E.; Storelvmo, T.

2013-12-01

292

Studies of Aerosol Vertical Profiles during GVAX Campaign Using Micropulse Lidar  

NASA Astrophysics Data System (ADS)

In February and March 2012 a Micropulse Lidar (MPL) operated by U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Mobile Facility (AMF) was deployed in Nainital (29.38°N, 79.5°E, 2000 m asl), during the Ganges Valley Aerosol Experiment (GVAX). In the absence of clouds, the MPL, operating at 532 nm, produces profiles of atmospheric scattering that result from aerosols (Mie scattering) and molecules (Rayleigh-scattering). In combination with aerosol optical depth (AOD) data from the nearly co-located multifilter rotating shadowband radiometer (MFRSR), these data are used to calculate vertical profiles of aerosol extinction coefficients and AODs. The raw data used in this study are averaged in time for 10 seconds and 15 meters in altitude. Preliminary results indicate that aerosols were confined mostly below 1.5 to 2 km but with additional significant aerosol contributions up to 4-5 km. In some cases two distinct aerosol layers at different heights were also observed. The lower aerosol layer might be associated with penetration of accumulated aerosol from the nearby Ganges Valley to the site whereas upper layer may be due to the residual aerosols. A clear diurnal variation in aerosol extinction coefficients and AODs with higher values during the late afternoon was observed. Moreover, the aerosol extinction coefficients and AODs are higher in March as compared to the corresponding values in February. In order to assess the possible sources of the aerosol layers a seven days air-back trajectory analysis using NOAA-HYSPLIT model during these two months will also be presented.

Kafle, D. N.; Coulter, R. L.

2012-12-01

293

Dust Aerosol Analysis and Prediction with Lidar Observations and Ensemble Kalman Filter  

NASA Astrophysics Data System (ADS)

We have developed a state-of-the-art data assimilation system for a global aerosol model with a four dimensional Ensemble Kalman Filter (4D-EnKF) in which Lidar observations, i.e., attenuated backscattering coefficient, depolarization ratio, and extinction coefficient, were successfully assimilated. The concentrations of dust, sulfate, and seasalt aerosols as well as the dust surface emission intensity were treated as control variables in this data assimilation system. The Lidar observations were obtained from the Level 1B dataset of the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) or the dataset of the East Asian ground-based Lidar network operated by the National Institute for Environmental Studies of Japan (NIES). With the use of these Lidar observations and 4D-EnKF system, aerosol data assimilation and prediction experiments were globally performed in the spring (March - May) of 2007. In this paper, we especially focus on the analysis and prediction of Asian dust which is a seasonal meteorological phenomenon sporadically affecting East Asian countries during the springtime. The analysis and prediction results derived from satellite and ground-based observations were compared with each other, and validated by independent observations: 1) aerosol optical depth measured by the Moderate Resolution Imaging Spectro-radiometer (MODIS) over East Asia, and 2) weather reports on aeolian dust events in East Asia derived from the World Meteorological Organization (WMO) Surface Synoptic Observations (SYNOP). Forecast scores were estimated by phenomenal discrimination (i.e. hit or not) using the SYNOP weather reports and a threshold of modeled dust surface concentration, for example, 100 micrograms/m3. Detailed four-dimensional structures of dust outflows from source regions, such as Taklimakan or Gobi desert, to the Pacific Ocean over the Korean Peninsula or the Japanese Archipelago were well reproduced by this data assimilation system. The intensity of dust emission at each grid point was also adjusted as a consequence of the inversion analysis of the four dimensional data assimilation. The short-range dust prediction was generally improved by using the results of the data assimilation analysis as initial conditions. These results are valuable for the comprehensive analysis of aerosol behavior as well as aerosol forecasting.

Sekiyama, T. T.; Tanaka, T. Y.; Shimizu, A.; Miyoshi, T.

2010-12-01

294

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

NASA Technical Reports Server (NTRS)

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

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

2010-01-01

295

Validation of aerosol and cloud layer structures from the space-borne lidar CALIOP using a ground-based lidar in Seoul, Korea  

NASA Astrophysics Data System (ADS)

We present initial validation results of the space-borne lidar CALIOP onboard CALIPSO satellite using coincidental observations from a ground-based lidar in Seoul National University (SNU), Seoul, Korea (37.46° N, 126.95° E). We analyze six selected cases between September 2006 and February 2007, including 3 daytime and 3 night-time observations and covering different types of clear and cloudy atmospheric conditions. Apparent scattering ratios calculated from the two lidar measurements of total attenuated backscatter at 532 nm show similar aerosol and cloud layer structures both under cloud-free conditions and in cases of multiple aerosol layers underlying semi-transparent cirrus clouds. Agreement on top and base heights of cloud and aerosol layers is generally within 0.10 km, particularly during night-time. This result confirms that the CALIPSO science team algorithms for the discrimination of cloud and aerosol as well as for the detection of layer top and base altitude provide reliable information in such atmospheric conditions. This accuracy of the planetary boundary layer top height under cirrus cloud appears, however, limited during daytime. Under thick cloud conditions, however, information on the cloud top (bottom) height only is reliable from CALIOP (ground-based lidar) due to strong signal attenuations. However, simultaneous space-borne CALIOP and ground-based SNU lidar (SNU-L) measurements complement each other and can be combined to provide full information on the vertical distribution of aerosols and clouds. An aerosol backscatter-to-extinction ratio (BER) estimated from lidar and sunphotometer synergy at the SNU site during the CALIOP overpass is assessed to be 0.023±0.004 sr-1 (i.e. a lidar ratio of 43.2±6.2 sr) from CALIOP and 0.027±0.006 sr-1 (37.4±7.2 sr) from SNU-L. For aerosols within the planetary boundary layer under cloud-free conditions, the aerosol extinction profiles from both lidars are in agreement within about 0.02 km-1. Under semi-transparent cirrus clouds, such profiles also show good agreement for the night-time CALIOP flight, but large discrepancies are found for the daytime flights due to a small signal-to-noise ratio of the CALIOP data.

Kim, S.-W.; Berthier, S.; Raut, J.-C.; Chazette, P.; Dulac, F.; Yoon, S.-C.

2008-07-01

296

1.5 microns and the future of unattended aerosol lidar  

NASA Astrophysics Data System (ADS)

Unattended lidars operating in the mid-visible region for clouds and aerosols are currently deployed at tens of locations in the U.S. and in other countries. The micro-pulse lidar known as MPL is a very successful instrument in terms of numbers deployed, and it is also very sophisticated. In order to operate during daytime, micro-pulse lidars must have an extremely narrow field of view (FOV) and a very small optical bandpass. They are consequently not inexpensive, they tend to suffers from mechanical instability, and they are not field-serviceable when certain types of failures occur. In order to establish the optimum wavelength region for an unattended aerosol lidar, the spectral dependencies of eye safety standards, sky radiance, laser availability, detector performance, atmospheric optical properties, and optical materials are presented. In particular, eye safety standards allow a fluence of 1 J/cm^2 at 1.5 micron, which is 10^7 times the fluence allowed in the mid-visible. Pulse energies on the order of 10 mJ are sufficient to make daytime operation easy and low-cost. A conventional bistatic lidar configuration can then be used with a field of view on the order of milliradians, which eliminates the problem of mechanical instability, and the optical bandpass can be limited with an inexpensive interference filter. In addition, the InGaAs detectors used at 1.5 microns are much less susceptible to optical damage than the Geiger-mode silicon avalanche photodiodes (APDs) used in visible-light lidars.

Gimmestad, Gary G.; Roberts, David W.

2005-05-01

297

COMPACT OZONE LIDAR FOR ATMOSPHERIC OZONE AND AEROSOL MEASUREMENTS  

Microsoft Academic Search

A small compact ozone differential absorption lidar capable of being deployed on a small aircraft or unpiloted atmospheric vehicle (UAV) has been tested. The Ce:LiCAF tunable UV laser is pumped by a quadrupled Nd:YLF laser. Test results on the laser transmitter demonstrated 1.4 W in the IR and 240 mW in the green at 1000 Hz. The receiver consists of

Joel Marcia; Hani E. Elsayed-Ali

298

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

NASA Technical Reports Server (NTRS)

We are in the process of developing a nadir-viewing, aircraft-based high spectral resolution lidar (HSRL) at NASA Langley Research Center. The system is designed to measure backscatter and extinction of aerosols and tenuous clouds. The primary uses of the instrument will be to validate spaceborne aerosol and cloud observations, carry out regional process studies, and assess the predictions of chemical transport models. In this paper, we provide an overview of the instrument design and present the results of simulations showing the instrument's capability to accurately measure extinction and extinction-to-backscatter ratio.

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

2002-01-01

299

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

NASA Technical Reports Server (NTRS)

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

Korb, C. Laurence; Flesia, Cristina

1998-01-01

300

Distribution of atmospheric aerosols and CO2 lidar backscatter simulation  

NASA Technical Reports Server (NTRS)

Development of a Global Wind Measurement Satellite System (WINDSAT) (NOAA, 1981) requires a knowledge of the global characteristics of the free tropospheric and lower stratospheric aerosol. In particular, there is a need to document the behavior of the aerosol backscattering function, at CO2 laser wavelengths, beta sub CO2, as a function of space and time. There is, however, a relative lack of data for the free troposphere, particularly over the remoter regions of the globe, as compared with that for the boundary layer and the stratosphere. Moreover, because of variations in concentration that occur as a function of space and time, large data sets are required to obtain meaningful averages. A recent study by Kent et al. (1985) uses three distinct tropospheric aerosol data sets in order to obtain an improved global model of the general aerosol characteristics, including variation of beta sub CO2 with latitude, season, and altitude. The more important findings are summarized.

Kent, G. S.; Wang, P. H.; Deepak, A.; Farrukh, U. O.

1985-01-01

301

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

302

Lidar observation of the 2011 Puyehue volcanic aerosols at Lauder, New Zealand  

NASA Astrophysics Data System (ADS)

On June 4, 2011, the Puyehue-Cordon Caulle volcanic complex (40.6S, 72.1W) in Chile erupted violently and injected volcanic aerosols into the atmosphere. For the safety of civil aviation, continuous lidar observations were made at Lauder, New Zealand (45.0S, 169.7E), during 11 June through 6 July 2011. To study the influence of the volcanic aerosols on the Greenhouse gases Observing SATellite (GOSAT) products, we analyzed lidar data at a wavelength of 532 nm. The volcanic aerosols had large depolarization ratios (about 20-35%) around 10-15 km. A high depolarization ratio after 20 days of the eruption indicates that few spherical sulfuric acid particles were produced as injected amount of SO2 by the eruption was very small (Clarisse. et al. 2012). The time series of the backscattering ratio had three peaks with a period of about 10 days. The peak backscattering ratios were 8.71 at 10.6 km on 11 June, 8.63 at 11.63 km on 24 June, 6.00 at 11.08 km on 6 July, respectively. The optical depth of the volcanic aerosols was 0.5 on 11 June that started the observation. The impact of the volcanic aerosols on the GOSAT product will be presented.

Nakamae, K.; Uchino, O.; Morino, I.; Liley, B.; Sakai, T.; Nagai, T.; Yokota, T.

2012-12-01

303

Retrieval of aerosol size distribution based on GCV regularization with optical data of lidar  

NASA Astrophysics Data System (ADS)

Atmospheric aerosol particles influence the Earth's radiation balance both directly and indirectly. The aerosol size distribution (ASD) is one of the most important microphysical properties. In this paper, the generalized cross-validation (GCV) regularization method is used for the retrieval of ASD from three-wavelength lidar optical data. The numerical simulations are carried out using synthetic backscatter and extinction coefficients. Simulations results demonstrate that the ASD depends on particle refractive index. Choosing the suitable refractive index is crucial to retrieve aerosol size distribution accurately. Moreover, the numerical results show that, for the same refractive index, it is more suitable to retrieve broad ASD, which has larger mode width ?. The GCV regularization method has been tested for a set of experimental data from three-wavelength lidar, which provides backscatter coefficient at 355, 532 and 1064 nm and extinction coefficient at 355 and 532 nm. Experimental result shows that the retrieved size distribution belongs to the urban industrial type and fine mode. The result shows good agreement with the actural atmospheric aerosol size distribution of local area. Both the simulation and the expriment demonstrate that the GCV regularization method is feasible to retrieve the aerosol size distribution.

Zhao, Hu; Hua, Dengxin; Di, Huige; Wang, Yufeng; Zhao, Huan; Mao, Jiandong

2013-10-01

304

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

305

Dust aerosol vertical structure measurements using three MPL lidars during 2008 China-U.S. joint dust field experiment  

NASA Astrophysics Data System (ADS)

The 2008 China-U.S. joint dust field experiment, which aims to estimate the effect of dust on radiative forcing and its associated climatic impacts, was conducted during the dust-intensive period from March to June of 2008 over the Loess Plateau of northwest China. Dust aerosol vertical profiles and long-range transport of dust storm were measured with the three MPL-net Micro-Pulse Lidar (MPL) systems as well as other ground-based instruments and spaceborne remote sensing techniques. In this study, to ensure the effectiveness of the retrieval results, an effective algorithm was introduced for retrieving aerosol optical properties and vertical profiles from Mie lidar measurements. The advantage of this algorithm is that Aerosol Optical Depth (AOD) retrieval from lidar measurements can be accomplished without the use of the so-called lidar ratio for the corresponding quantities obtained from the AERONET Sun photometer. Dust aerosol vertical profiles are derived successfully from three MPL lidar systems using this algorithm. A dust storm that affected a large part of northwest China on 2 May 2008 was studied using measurements obtained from the three ground-based lidar systems, satellite-borne instruments and NCEP reanalysis data. The results show that different aerosol vertical structures were present at each site, and the colder Siberia air mass and stronger and longer cyclones around Mongolia are key features leading to the dust storm.

Huang, Zhongwei; Huang, Jianping; Bi, Jianrong; Wang, Guoyin; Wang, Wencai; Fu, Qiang; Li, Zhanqing; Tsay, Si-Chee; Shi, Jinsen

2010-04-01

306

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

NASA Technical Reports Server (NTRS)

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

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

2010-01-01

307

Aerosol optical and microphysical properties as derived from collocated measurements using polarization lidar and direct sampling  

NASA Astrophysics Data System (ADS)

Collocated and simultaneous measurements of aerosols near the ground were conducted using a lidar and aerosol sampler at Tsukuba, Japan, to clarify the relationship between lidar-derived optical properties and in-situ microphysical properties. The total linear particle depolarization ratio (?p) ranged from 14% to 18% when nonspherical mineral dust particles were predominant in the supermicrometer range on May 7-8, 2008, whereas it ranged from 6% to 7% when spherical sea-salt particles were predominant in that range on September 3-4, 2008. Sulfates and nitrates were predominant in the submicrometer range for these two periods. Water-dialysis analysis on May 6-7 indicated that 29% of the coarse particles were water insoluble, whereas 70% were water soluble or nearly soluble on September 3-4. The ratio of dry mass concentration to the backscattering coefficient (M/?p) was 34-39 g m-2 sr on May 7-8 and 6.2-6.3 g m-2 sr on September 3-4. Our results provide evidence that lidar-derived ?p and ?p capture the aerosol mass concentration and relative abundance of the spherical and nonspherical particles although the microphysical properties vary significantly for individual particles.

Sakai, Tetsu; Nagai, Tomohiro; Mano, Yuzo; Zaizen, Yuji; Inomata, Yayoi

2012-12-01

308

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

NASA Technical Reports Server (NTRS)

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

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

1985-01-01

309

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

NASA Astrophysics Data System (ADS)

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

Gasteiger, J.; Freudenthaler, V.

2014-05-01

310

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

NASA Technical Reports Server (NTRS)

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

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

2011-01-01

311

Six-channel polychromator design and implementation for the UPC elastic/Raman lidar  

NASA Astrophysics Data System (ADS)

A 6-channel dichroic-based polychromator is presented as the spectrally selective unit for the U.P.C. elastic/Raman lidar. Light emission is made at 355-nm (ultraviolet, UV), 532-nm (visible, VIS) and 1064-nm (near infrared, NIR) wavelengths. In reception, the polychromator is the spectral separation unit that separates the laser backscattered composite return into 3 elastic (355, 532, 1064-nm wavelengths) and 3 Raman channels (386.7, 607.4 and 407.5-nm (water-vapor) wavelengths). The polychromator houses photo-multiplier tubes (PMT) for all the channels except for the NIR one, which is avalanche photodiode (APD) based. The optomechanical design uses 1-inch optics and Eurorack standards. The APD-based receiver uses a XY-axis translation/elevation micro-positioning stage due to its comparatively small active area and motorised neutral density filters are used in all PMT-based channels to avoid detector saturation. The design has been specially optimized to provide homogeneous spatial light distribution onto the photodetectors and good mechanical repeatability. All channels are acquired in mixed analog and photon-counting mode using Licel® transient recorders, which are controlled by means of a user friendly LabVIEWTM interface. The paper focuses on the main polychromator optical design parameters, that is, light collimation trade-offs, end-to-end transmissivity, net channel responsivity, light distribution and spot size onto the photodetectors. The polychromator along with the rest of the U.P.C. lidar system has successfully been tested during a recent lidar system intercomparison campaign carried out in Madrid (Spain) during Oct. 2010.

Kumar, Dhiraj; Rocadenbosch, Francesc; Sicard, Michaël; Comeron, Adolfo; Muñoz, Constantino; Lange, Diego; Tomás, Sergio; Gregorio, Eduard

2011-10-01

312

Compact Ozone Lidar for Atmospheric Ozone and Aerosol Measurements  

NASA Technical Reports Server (NTRS)

A small compact ozone differential absorption lidar capable of being deployed on a small aircraft or unpiloted atmospheric vehicle (UAV) has been tested. The Ce:LiCAF tunable UV laser is pumped by a quadrupled Nd:YLF laser. Test results on the laser transmitter demonstrated 1.4 W in the IR and 240 mW in the green at 1000 Hz. The receiver consists of three photon-counting channels, which are a far field PMT, a near field UV PMT, and a green PMT. Each channel was tested for their saturation characteristics.

Marcia, Joel; DeYoung, Russell J.

2007-01-01

313

Aerosol concentration measurements with a lidar ceilometer: results of a one year measuring campaign  

NASA Astrophysics Data System (ADS)

The Vaisala ceilometer CT25K is an eye-safe commercial lidar mainly used to report cloud base heights and vertical visibility for aviation safety purposes. Compared to ceilometers with biaxial optics, its single lens design provides a higher signal-to-noise ratio for lidar return signals from distances below about 600 m, thus increasing its abilities to examine the mixing layer. A CT25K ceilometer took part in the environmental research project VALIUM at the Lower Saxony State Agency for Ecology (NLO) in Hannover, Germany, investigating the air pollution in an urban surrounding with various sensors. Lidar return signals are reported every 15 s with a height resolution of 15 m. This paper covers two aspects of the interpretation of these signals. The aerosol backscatter of the atmosphere up to 30 m is compared to the PM10 concentration reported by an in situ sensor every 30 minutes, and the results are interpreted in respect of meteorological parameters such as humidity, temperature, wind, and global radiation. With relative humidity values below 62 % and no rain present the correlation between ceilometer backscatter and PM10 values is good enough to qualify standard ceilometers as instruments for a quantitative analysis of the atmospheric aerosol contents. Backscatter values up to 1000 m height are presented that allow an estimation of the convective boundary layer top in dry weather situations. The atmospheric boundary layer structures derived from ceilometer data are compared to those reported by a SODAR and a RASS that also took part in the VALIUM research project. Finally the backscatter data quality of a double lens ceilometer is compared to that of the single lens CT25K ceilometer to investigate to what extent these lidar systems are also able to report aerosol concentration.

Muenkel, Christoph; Emeis, Stefan; Mueller, Wolfgang J.; Schaefer, Klaus P.

2004-02-01

314

Estimating the backscatter spectral dependence and relative concentration for multiple aerosol materials from lidar data  

NASA Astrophysics Data System (ADS)

Detection and estimation of materials in the atmosphere by lidar has heretofore required that the spectral dependence of the relevant cross section coefficients -- backscatter in the case of aerosols and absorptivity for vapors -- be known in advance. While this typically is a reasonable assumption in the case of vapor, the aerosol backscatter coefficients are complicated functions of particle size, shape, and refractive index, and are therefore usually not well characterized a priori. Using incorrect parameters will give biased concentration estimates and impair discrimination ability. This paper describes an approach for estimating both the spectral dependence of the aerosol backscatter and relative concentration range-dependence of a set of materials using multi-wavelength lidar. The approach is based on state-space filtering that applies a Kalman filter in range for concentration, and updates the backscatter spectral estimates through a sequential least-squares algorithm at each time step. The method is illustrated on aerosol-release data of the bio-simulant ovalbumin collected by ECBC during field tests in 2002, as well as synthetic data sets.

Warren, Russell E.; Vanderbeek, Richard G.

2004-08-01

315

Improved simulation of aerosol, cloud, and density measurements by shuttle lidar  

NASA Technical Reports Server (NTRS)

Data retrievals are simulated for a Nd:YAG lidar suitable for early flight on the space shuttle. Maximum assumed vertical and horizontal resolutions are 0.1 and 100 km, respectively, in the boundary layer, increasing to 2 and 2000 km in the mesosphere. Aerosol and cloud retrievals are simulated using 1.06 and 0.53 microns wavelengths independently. Error sources include signal measurement, conventional density information, atmospheric transmission, and lidar calibration. By day, tenuous clouds and Saharan and boundary layer aerosols are retrieved at both wavelengths. By night, these constituents are retrieved, plus upper tropospheric, stratospheric, and mesospheric aerosols and noctilucent clouds. Density, temperature, and improved aerosol and cloud retrievals are simulated by combining signals at 0.35, 1.06, and 0.53 microns. Particlate contamination limits the technique to the cloud free upper troposphere and above. Error bars automatically show effect of this contamination, as well as errors in absolute density nonmalization, reference temperature or pressure, and the sources listed above. For nonvolcanic conditions, relative density profiles have rms errors of 0.54 to 2% in the upper troposphere and stratosphere. Temperature profiles have rms errors of 1.2 to 2.5 K and can define the tropopause to 0.5 km and higher wave structures to 1 or 2 km.

Russell, P. B.; Morley, B. M.; Livingston, J. M.; Grams, G. W.; Patterson, E. W.

1981-01-01

316

Lidar Measurements of Stratospheric and Tropospheric Aerosols at 1064 nm Using a New and Low-Noise Photomultiplier  

Microsoft Academic Search

Using a new type of photomultiplier (PMT) tube R3236 cooled to -30°C, and a photon counting method, lidar measurements of stratospheric aerosols and tropospheric aerosols above an altitude of 2.25 km were made at the fundamental wavelength of?=1064 nm of a Nd:YAG laser which is sensitive to aerosol scattering. The PMT R3236 was found to be useful even for measurements

Osamu Uchino; Hideyuki TAKASHIMA; Isao Tabata

1991-01-01

317

Features of upper troposphere and lower stratosphere aerosols observed by lidar over Gadanki, a tropical Indian station  

Microsoft Academic Search

Upper troposphere (UT) and lower stratosphere (LS) aerosol characteristics are studied over a tropical station Gadanki (13.5°N, 79.2°E), using 532-nm Nd:YAG lidar during 2001–2005. Scattering ratios (SR) and aerosol extinction are found to exhibit seasonal and interannual variations in UT (10–15 km) and LS (18–30 km). SR is about 1.00–1.2 in the 10- to 30-km altitude region. Aerosol extinction is

Padmavati Kulkarni; S. Ramachandran; Y. Bhavani Kumar; D. Narayana Rao; M. Krishnaiah

2008-01-01

318

Performance of the Lidar Design and Data Algorithms for the GLAS Global Cloud and Aerosol Measurements  

NASA Technical Reports Server (NTRS)

The Geoscience Laser Altimeter System (GLAS) launched in early 2003 is the first polar orbiting satellite lidar. The instrument design includes high performance observations of the distribution and optical scattering cross sections of atmospheric clouds and aerosol. The backscatter lidar operates at two wavelengths, 532 and 1064 nm. For the atmospheric cloud and aerosol measurements, the 532 nm channel was designed for ultra high efficiency with solid state photon counting detectors and etalon filtering. Data processing algorithms were developed to calibrate and normalize the signals and produce global scale data products of the height distribution of cloud and aerosol layers and their optical depths and particulate scattering cross sections up to the limit of optical attenuation. The paper will concentrate on the effectiveness and limitations of the lidar channel design and data product algorithms. Both atmospheric receiver channels meet and exceed their design goals. Geiger Mode Avalanche Photodiode modules are used for the 532 nm signal. The operational experience is that some signal artifacts and non-linearity require correction in data processing. As with all photon counting detectors, a pulse-pile-up calibration is an important aspect of the measurement. Additional signal corrections were found to be necessary relating to correction of a saturation signal-run-on effect and also for daytime data, a small range dependent variation in the responsivity. It was possible to correct for these signal errors in data processing and achieve the requirement to accurately profile aerosol and cloud cross section down to 10-7 llm-sr. The analysis procedure employs a precise calibration against molecular scattering in the mid-stratosphere. The 1064 nm channel detection employs a high-speed analog APD for surface and atmospheric measurements where the detection sensitivity is limited by detector noise and is over an order of magnitude less than at 532 nm. A unique feature of the GLAS is a full acquisition of the surface return pulse, which has important application to the atmospheric transmission retrieval.

Spinhirne, James D.; Palm, Stephen P.; Hlavka, Dennis L.; Hart, William D.

2007-01-01

319

Cloud and Aerosol Measurements from the GLAS Polar Orbiting Lidar: First Year Results  

NASA Technical Reports Server (NTRS)

The Geoscience Laser Altimeter System (GLAS) launched in 2003 is the first polar orbiting satellite lidar. The instrument was designed for high performance observations of the distribution and optical scattering cross sections of clouds and aerosol. GLAS is approaching six months of on orbit data operation. These data from thousands of orbits illustrate the ability of space lidar to accurately and dramatically measure the height distribution of global cloud and aerosol to an unprecedented degree. There were many intended science applications of the GLAS data and significant results have already been realized. One application is the accurate height distribution and coverage of global cloud cover with one goal of defining the limitation and inaccuracies of passive retrievals. Comparison to MODIS cloud retrievals shows notable discrepancies. Initial comparisons to NOAA 14&15 satellite cloud retrievals show basic similarity in overall cloud coverage, but important differences in height distribution. Because of the especially poor performance of passive cloud retrievals in polar regions, and partly because of high orbit track densities, the GLAS measurements are by far the most accurate measurement of Arctic and Antarctica cloud cover from space to date. Global aerosol height profiling is a fundamentally new measurement from space with multiple applications. A most important aerosol application is providing input to global aerosol generation and transport models. Another is improved measurement of aerosol optical depth. Oceanic surface energy flux derivation from PBL and LCL height measurements is another application of GLAS data that is being pursued. A special area of work for GLAS data is the correction and application of multiple scattering effects. Stretching of surface return pulses in excess of 40 m from cloud propagation effects and other interesting multiple scattering phenomena have been observed. As an EOS project instrument, GLAS data products are openly available to the science community. First year results from GLAS are summarized.

Spinhirne, J. D.; Palm, S. P.; Hlavka, D. L.; Hart, W. D.; Mahesh, A.; Welton, E. J.

2004-01-01

320

Observation of aerosol in the mixing layer by a ground-based lidar ceilometer  

NASA Astrophysics Data System (ADS)

The Vaisala ceilometer CT25K is an eye-safe commercial lidar mainly used to report cloud base heights and vertical visibility for aviation safety purposes. Compared to ceilometers with bi-axial optics, its single-lens design provides a higher signal-to-noise ratio for lidar return signals from distances below about 600 m, thus increasing its abilities to examine the mixing layer. A CT25K ceilometer takes part in the environmental measuring campaign VALIUM at the Lower Saxony State Agency for Ecology (NLO) in Hannover, Germany, investigating the air pollution in an urban surrounding with various sensors. Lidar return signals are reported every 15 s with a height resolution of 15 m. This paper concentrates on the interpretation of these signals in respect of the aerosol backscatter of the atmosphere up to 30 m. Every 30 minutes the NLO reports PM10 and PM2.5 concentrations measured with in-situ sensors installed 20 m above the ceilometer. Humidity and precipitation monitor sensors help ruling out weather situations with water droplets contributing mainly to the ceilometer backscatter signal. Data collected between 01. 03. 2002 and 31. 07. 2002 show that during dry weather situations there is a correlation of more than 80% between the dust concentration and the aerosol backscatter, allowing a quantitative analysis of the atmospheric dust contents with a standard ceilometer. The ratio PM10/PM2.5 of in situ measurements is investigated also giving a regression function and a correlation coefficient.

Muenkel, Christoph; Emeis, Stefan M.; Mueller, Wolfgang J.; Schaefer, Klaus P.

2003-04-01

321

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

322

Extensive ground-based Lidar and Radiometer Measurements of Aerosol and Cloud for the Comparison and Validation of CALIPSO retrievals  

Microsoft Academic Search

We present the results of collocated measurements from CCNY ground-based multiwavelength Raman-Mie lidar and a CIMEL Sun\\/sky radiometer with CALIPSO overpasses near New York City (40.821N,73.949W). The data set consists of 19 days of observations conducted under the clear, hazy, and cloudy skies. In particular, statistical comparisons are made between the CALIPSO Level-2 5-km layer products and the ground-based lidar

Y. Wu; B. Herman; B. Gross; F. Moshary; S. Ahmed

2008-01-01

323

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

NASA Technical Reports Server (NTRS)

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

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

1986-01-01

324

Upper tropospheric water vapor: A field campaign of two Raman lidars, Airborne hygrometers, and Radiosondes  

NASA Technical Reports Server (NTRS)

Water vapor in the atmosphere plays an important role in radiative transfer and the process of radiative balance so critical for understanding global change. It is the principal ingredient in cloud formation, one of the most difficult atmospheric processes to model, and the most variable component of the Earth-atmosphere albedo. And as a free molecule, it is the most active infrared absorber and emitter, thus, the most important greenhouse gas. The radiative impact of water vapor is important at all levels of the atmosphere. Even though moisture decreases by several orders-of-magnitude from the Earth's surface to the tropopause, recent research has shown that, from a radiative standpoint, a small percentage change in water vapor at any level is nearly equivalent. Therefore accurate and precise measurements of this important atmospheric constituent are needed at all levels to evaluate the full radiative impact. The need for improved measurements in the upper troposphere is particularly important because of the generally hostile (very dry and cold) conditions encountered. Because of the importance of water vapor to the understanding of radiative transfer, the Department of Energy's Atmospheric Radiation Measurements (ARM) program initiated a series of measurement campaigns at the Cloud And Radiation Testbed (CART) site in Oklahoma, especially focused on atmospheric water vapor. Three water vapor intensive observation period (water vapor IOP) campaigns were planned. Two of the water vapor IOP campaigns have been completed: the first IOP was held during the fall of 1996 with a focus on boundary layer water vapor measurements, and the second was conducted during the fall of 1997 with a focus on both boundary layer moisture e and moisture in the upper troposphere. This paper presents a review of the intercomparisons of water vapor measurements in the upper troposphere aquired during the second water vapor IOP. Data to be presented include water vapor measurements ements from: two Raman Lidars, the NASA Goddard Scanning Raman Lidar (SRL) and the CART Raman Lidar (CARL), a number of Vaisala radiosondes launched during the IOP campaign, and a dew point hygrometer flown on the University of North Dakota Cessna Citation Aircraft.

Melfi, S. Harvey; Turner, Dave; Evans, Keith; Whiteman, Dave; Schwemmer, Geary; Ferrare, Richard

1998-01-01

325

Lidar and in situ observations of continental and Saharan aerosol: closure analysis of particles optical and physical properties  

Microsoft Academic Search

Single wavelength polarization lidar observations collected at Mt. Cimone (44.2° N, 10.7° E, 1870 m a.s.l.) during the June 2000 MINATROC campaign are analyzed to derive tropospheric profiles of aerosol extinction, depolarization, surface area and volume. Lidar retrievals for the 2170-2245 m level are compared to the same variables as computed from in situ measurements of particles size distributions, performed

G. P. Gobbi; F. Barnaba; R. van Dingenen; J. P. Putaud; M. Mircea; M. C. Facchini

2003-01-01

326

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 mum 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

327

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

328

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

NASA Technical Reports Server (NTRS)

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

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

2014-01-01

329

Inclined lidar observations of boundary layer aerosol particles above the Kongsfjord, Svalbard  

NASA Astrophysics Data System (ADS)

An inclined lidar with vertical resolution of 0.4 m was used for detailed boundary layer studies and to link observations at Zeppelin Mountain (474 m) and Ny-Ålesund, Svalbard. We report on the observation of aerosol layers directly above the Kongsfjord. On 29 April 2007, a layer of enhanced backscatter was observed in the lowest 25 m above the open water surface. The low depolarization ratio indicated spherical particles. In the afternoon, this layer disappeared. The ultrafine particle concentration at Zeppelin and Corbel station (close to the Kongsfjord) was low. On 1 May 2007, a drying process in the boundary layer was observed. In the morning, the atmosphere up to Zeppelin Mountain showed enhanced values of the backscatter coefficient. Around noon, the top of the highly reflecting boundary layer decreased from 350 to 250 m. The top of the boundary layer observed by lidar was confirmed by radiosonde data.

Lampert, Astrid; Ström, Johan; Ritter, Christoph; Neuber, Roland; Yoon, Young Jun; Chae, Nam Yi; Shiobara, Masataka

2012-10-01

330

Troposphere-Stratosphere transport in the tropics from CALIPSO lidar aerosols measurements  

NASA Astrophysics Data System (ADS)

Troposphere Stratosphere transport in the tropics from CALIPSO lidar aerosols measurements J.P. Vernier, J.P. Pommereau, A. Garnier and J. Pelon CNRS-LATMOS Verrières le Buisson, 91371 France The evolution of the aerosols in the tropical tropopause region is investigated from the CALIOP lidar measurements onboard the CALIPSO satellite. After applying a correction for calibration and appropriate cloud mask, a consistent picture of the aerosols since the beginning of the mission in June 2006 until present is provided. Most remarkable features are the presence of several volcanic plumes at various levels further lifted by the Brewer-Dobson circulation, and the injection of clean washed-out tropospheric air up to 19-20 km particularly intense during the maximum land convective season in February-March resulting in the cleansing of the Tropical Tropopause Layer (TTL). Most important implications relevant to Troposphere to Stratosphere transport is the suggestion of the existence of a maximum static stability layer at about 19.5 km (450 K, 60 hPa) suggesting a decoupling of the circulation between Holton's "lowermost stratosphere" and "overworld", and the importance at global scale of fast convective overshooting of tropospheric air across the tropopause up to the altitude of the above static layer.

Vernier, J.-P.; Pommereau, J.-P.; Garnier, A.; Pelon, J.

2009-04-01

331

Lidar Investigation of Tropical Nocturnal Boundary Layer Aerosols and Cloud Macrophysics  

SciTech Connect

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

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

2013-10-01

332

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

SciTech Connect

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

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

2009-07-10

333

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

334

Raman Lidar Measurements of Water Vapor and Cirrus Clouds During The Passage of Hurricane Bonnie  

NASA Technical Reports Server (NTRS)

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 focussed 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 based on a comparison of lidar and GOES 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 approximately 0.005 or greater. Using the ISCCP detection threshold for cirrus clouds on the GOES data presented here, a high bias of up to 40% in the GOES precipitable water retrieval was found.

Whiteman, D. N.; Evans, K. D.; Demoz, B.; Starr, D OC.; Eloranta, E. W.; Tobin, D.; Feltz, W.; Jedlovec, G. J.; Gutman, S. I.; Schwemmer, G. K.; Smith, David E. (Technical Monitor)

2000-01-01

335

Raman Lidar Measurements During the International H2O Project. 2; Instrument Comparisons and Case Studies  

NASA Technical Reports Server (NTRS)

The NASA/GSFC Scanning Raman Lidar (SRL) participated in the International H2O Project (IHOP) that occurred in May and June, 2002 in the midwestern part of the U. S. The SRL system configuration and methods of data analysis were described in part I of this paper. In this second part, comparisons of SRL water vapor measurements and those of chilled mirror radiosonde and LASE airborne water vapor lidar are performed. Two case studies are presented; one for daytime and one for nighttime. The daytime case study is of a convectively driven boundary layer event and is used to characterize the SRL water vapor random error characteristics. The nighttime case study is of a thunderstorm-generated cirrus cloud case that is studied in it s meteorological context. Upper tropospheric humidification due to precipitation from the cirrus cloud is quantified as is the cirrus cloud ice water content and particle depolarization ratio. These detailed cirrus cloud measurements are being used in a cirrus cloud modeling study.

Whiteman, D. N.; Demoz, B.; DiGirolamo, P.; Corner, J.; Veselovskii, I.; Evans, K.; Wang, Z.; Sabatino, D.; Schwemmer, G.; Gentry, B.

2005-01-01

336

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

337

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

338

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

NASA Technical Reports Server (NTRS)

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

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

2007-01-01

339

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

NASA Technical Reports Server (NTRS)

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

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

2004-01-01

340

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

NASA Technical Reports Server (NTRS)

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

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

2005-01-01

341

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

342

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

PubMed

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. PMID:21614108

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

2011-05-20

343

Lidar  

NASA Technical Reports Server (NTRS)

Lidar is an optical radar technique employing laser energy. Variations in signal intensity as a function of range provide information on atmospheric constituents, even when these are too tenuous to be normally visible. The theoretical and technical basis of the technique is described and typical values of the atmospheric optical parameters given. The significance of these parameters to atmospheric and meteorological problems is discussed. While the basic technique can provide valuable information about clouds and other material in the atmosphere, it is not possible to determine particle size and number concentrations precisely. There are also inherent difficulties in evaluating lidar observations. Nevertheless, lidar can provide much useful information as is shown by illustrations. These include lidar observations of: cirrus cloud, showing mountain wave motions; stratification in clear air due to the thermal profile near the ground; determinations of low cloud and visibility along an air-field approach path; and finally the motion and internal structure of clouds of tracer materials (insecticide spray and explosion-caused dust) which demonstrate the use of lidar for studying transport and diffusion processes.

Collis, R. T. H.

1969-01-01

344

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

345

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

PubMed

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

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

1997-07-20

346

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

347

Confocal microprobe Raman imaging of urban tropospheric aerosol particles.  

PubMed

Particulate matter with aerodynamic diameters of < 1, 1-2.5, and 2.5-10 microm were collected during two seasons in two urban zones situated northeast and southwest, respectively, of a lead/zinc smelter located in a former mining region of northern France. We demonstrate the effectiveness of the combined use of computer-controlled Raman mapping and multivariate curve resolution (MCR) of the Raman images to determine heterogeneous chemistry at the level of aerosol particle. The resulting molecular images of major species were found to be in accurate agreement with elemental images obtained by WDS X-ray-mapping. Environmental SEM was very useful to localize spare metal-rich particles before Raman mapping. Some spare particles containing pyromorphite (Pb5(PO4)3OH) and franklinite (ZnxFe3-xO4) mixed with mineral dust were detected at the northeast (NE) sampling site, when the wind was blowing from the west (W) sector. These particles were probably suspended in the troposphere by the action of wind or by mechanical disturbance of polluted top soils. The most abundantly encountered particles in the 10-2.5 and 2.5-1 microm fractions were found to be aggregates of NaCl, CaCO3, CaSO4 x 2H2O, CaMg(CO3)2, SiO2, feldspar, clay minerals, alpha-Fe2O3, NaNO3, and Ca(NO3)2 x 4H20. Black carbon and (NH4)2SO4 particles were observed predominantly in the finest fraction. It was not rare to detect Pb and Zn-rich particles in the 10-2.5 and 2.5-1 microm fractions collected at the southwest (SW) sampling site, when the wind was blowing from the NE sector. Most of these mixed particles probably result from the aggregation between PbSO4, PbO x PbSO4, and ZnS particles emitted by the smelters and hydroscopic mineral dust during transport in the troposphere. PMID:16572789

Batonneau, Yann; Sobanska, Sophie; Laureyns, Jacky; Bremard, Claude

2006-02-15

348

Intercomparisons of high-resolution solar blind Raman lidar atmospheric profiles of water vapor with radiosondes and kytoon  

NASA Technical Reports Server (NTRS)

A report is given of measurements of atmospheric profiles of water vapor in the boundary layer by use of solar blind Raman lidar. These measurement episodes, occuring twice a day over a two week period, were accompanied by a dense net of supporting measurements. The support included two radiosonde launches per measurement episodes as well as a kytoon support measurement of water vapor using a wet bulb-dry bulb instrument. The kytoon strategy included ten minute stops at strategic altitudes. Additional kytoon measurements included ozone profiles and nephelometric extinction profiles in the visible. Typically, six or seven 1000 shot lidar profile averages were collected during a measurement episode. Overall performance comparisons are provided and intercomparisons between auxiliary measurement devices are presented. Data on the accuracy of the lidar water vapor profiles are presented.

Petri, K.; Salik, A.; Cooney, J.

1986-01-01

349

Optical designs for improving performances of aerosol sensing micro-pulse lidars  

NASA Astrophysics Data System (ADS)

This paper addresses current design improvement issues of aerosol sensing Micro-Pulse Lidars (MPL). MPLs are designed to adhere to eye-safety restrictions while achieving acceptable signal to noise ratios (SNR). This method is realized by reducing the per pulse energy of the laser and employing a narrow receiver field-of-view (FOV). Due to the narrow FOV requirement, only a partial return signal is measured until the laser beam propagates a distance where the receiver FOV fully overlaps the laser beam. This is called the full overlap distance and is usually 4 km or more for reasonable MPL parameters. Accurate MPL measurements are typically only possible beyond this distance. The fraction of laser beam energy that is within the receiver FOV versus range is called the overlap function. The causes of the overlap function are discussed. An overlap related problem with current MPL designs is that the majority of the atmospheric aerosols are located below an altitude of 4 km to 5 km, within the partial overlap region. Another problem is that the overlap function is not thermally constant. This introduces errors in the experimentally derived overlap function and system constant factor, ultimately leading to errors in the retrieved lidar signal.

Rubio, Manuel; Reagan, John A.

2002-01-01

350

Investigation of the aerosol structure over an urban area using a polarization lidar.  

PubMed

The paper presents a lidar study of the aerosol structure in the planetary boundary layer in the case of radiation fog and haze. A conceptual model of the dynamics of the depolarization coefficient profile during the mixing layer development, taking into account the presence of a multilayered inversions and radiation fogs, is proposed. Various techniques are employed in the processing of the lidar signal in order to determine the mixing layer height as well as more details of the aerosol structure in the low atmosphere, namely, finding the maximum of the signal returned from the lowest temperature inversion, the crossing point of the S function's first derivative with the x axis, and profiles of the depolarization ratio. After the complete destruction of the stable stratification, a low constant value of the depolarization ratio within the newly formed mixing layer is being observed. The study of stable boundary layer disintegration and convective boundary layer formation in the presence of fogs and/or clouds is of both scientific and practical significance in what concerns the protection of the environment and the aviation meteorology. PMID:15480498

Kolev, Nikolay; Tatarov, Boyan; Kaprielov, Boiko; Kolev, Ivan

2004-10-01

351

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

NASA Technical Reports Server (NTRS)

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

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

1985-01-01

352

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

353

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

354

Aerosol Transport Questions Arising From Micro Pulse Lidar Measurements During MILAGRO  

NASA Astrophysics Data System (ADS)

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

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

2007-12-01

355

Twin Doppler Rayleigh\\/Mie\\/Raman lidar for wind and temperature measurements in the middle atmosphere up to 80 km  

Microsoft Academic Search

A direct detection Doppler shift system for measuring wind speed in the middle atmosphere up to 80 km with 2 h resolution was implemented in the ALOMAR Rayleigh\\/Mie\\/Raman lidar (69° N, 16° E). The statistical uncertainty of the line of sight wind is about 0.6 m\\/s and 10 m\\/s at 49 km and 80 km, respectively. We use a Doppler

G. Baumgarten

2010-01-01

356

Lidar backscatter to extinction, mass and area conversions for stratospheric aerosols based on midlatitude balloonborne size distribution measurements  

Microsoft Academic Search

Size distributions of the stratospheric sulfuric acid aerosol derived from balloonborne particle counter measurements from Laramie, Wyoming, are used to calculate ratios of particle extinction, mass, and surface area to particle backscatter, and the wavelength dependences of particle backscatter and extinction. These ratios may then be used to infer particle extinction, mass, and area from midlatitude lidar data in the

Horst Jäger; Terry Deshler

2002-01-01

357

LIDAR Observations of the Vertical Ozone and Aerosol Distribution over Mexico City during the MCMA-2003 Field Campaign  

Microsoft Academic Search

An international field measurement campaign was held in April - May 2003 in the Mexico City Metropolitan Area (MCMA) as part of an effort to understand the complex urban air pollution problems in large cities. Gas phase and aerosol constituents were studied intensively during the campaign. LIDAR played an important role for measuring boundary layer dynamics and photochemical processes by

V. Simeonov; P. Ristori; M. Taslakov; T. Dinoev; H. van den Bergh; S. Frey; L. T. Molina; M. J. Molina

2004-01-01

358

Parallel software for retrieval of aerosol distribution from LIDAR data in the framework of EARLINET-ASOS  

Microsoft Academic Search

We present new software for the retrieval of the volume distribution - and thus, other relevant microphysical properties such as the effective radius - of stratospheric and tropospheric aerosols from multiwavelength LIDAR data. We consider the basic equation as a linear ill-posed problem and solve the linear system derived from spline collocation. We consider as well the technical implications of

Lukas Osterloh; Carlos Pérez; David Böhme; José María Baldasano; Christine Böckmann; Lars Schneidenbach; David Vicente

2009-01-01

359

Statistical analysis of the spatial-temporal distribution of aerosol extinction retrieved by micro-pulse lidar in Kashgar, China.  

PubMed

The spatial-temporal distribution of dust aerosol is important in climate model and ecological environment. An observation experiment of the aerosol vertical distribution in the low troposphere was made using the micro-pulse lidar system from Sept. 2008 to Aug. 2009 at the oasis city Kashgar, China, which is near the major dust source area of the Taklimakan desert. The monthly averaged temporal variation of aerosol extinction profiles are given in the paper. The profile of aerosol extinction coefficient suggested that the dust aerosol could be vertically transported from the ground level to the higher altitude of above 5 km around the source region, and the temporal distribution showed that the dust aerosol layer of a few hundred meters thick appeared in the seasons of early spring and summer near the ground surface. PMID:23481711

Zhu, Wenyue; Xu, Chidong; Qian, Xianmei; Wei, Heli

2013-02-11

360

Investigating the Internal Structure of Individual Aerosol Particles Using Atomic Force and Raman Microscopies  

NASA Astrophysics Data System (ADS)

We have used Atomic Force Microscopy (AFM) and Raman Microscopy to probe aerosol internal structures in order to understand the optical properties of aerosols composed of mixtures of organic and inorganic components. While AFM gives only topographical information about the particles, indirect chemical information can be obtained by using substrates with different surface properties. With Raman microscopy, chemical signatures of the components of the aerosol are obtained, but we have limited spatial resolution. We have explored the use of these two techniques to look at aerosol internal structure using a range of different model aerosols composed of mixtures of ammonium sulfate with organic compounds of various solubilities such as sucrose, succinic acid, and palmitic acid. At the extremes of solubility, AFM provides suitable information for interpreting aerosol microstructure. For example, AFM clearly shows the presence of core-shell structures for aerosol