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Sample records for aerosol extinction backscatter

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

    NASA Technical Reports Server (NTRS)

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

    1998-01-01

    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.

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

    NASA Technical Reports Server (NTRS)

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

    2006-01-01

    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.

  3. Use of Lidar Derived Optical Extinction and Backscattering Coefficients Near Cloud Base to Explore Aerosol-Cloud Interactions

    NASA Astrophysics Data System (ADS)

    Han, Zaw; Wu, Yonhgua; Gross, Barry; Moshary, Fred

    2016-06-01

    Combination of microwave radiometer (MWR) and mutlifilter rotating shadowband radiometer (MFRSR) measurement data together with SBDART radiative transfer model to compute cloud optical depth (COD) and cloud droplet effective radius (Reff). Quantify the first aerosol indirect effect using calculated Reff and aerosol extinction from Raman lidar measurement in urban coastal region. Illustrate comparison between ground-based and satellite retrievals. Demonstrate relationship between surface aerosol (PM2.5) loading and Reff. We also explain the sensitivity of aerosol-cloud-index (ACI) depend on the aerosol layer from cloud base height. Potential used of less noisy elastic backscattering to calculate the ACI instead of using Raman extinction. We also present comparison of elastic backscattering and Raman extinction correlation to Reff.

  4. Extinction-to-Backscatter Ratios of Lofted Aerosol Layers Observed During the First Three Months of CALIPSO Measurements

    NASA Technical Reports Server (NTRS)

    Omar, Ali H.; Vaughan, Mark A.; Liu, Zhaoyan; Hu, Yongxiang; Reagan, John A.; Winker, David M.

    2007-01-01

    Case studies from the first three months of the Cloud and Aerosol Lidar and Infrared Pathfinder Spaceborne Observations (CALIPSO) measurements of lofted aerosol layers are analyzed using transmittance [Young, 1995] and two-wavelength algorithms [Vaughan et al., 2004] to determine the aerosol extinction-to-backscatter ratios at 532 and 1064 nm. The transmittance method requires clear air below the layer so that the transmittance through the layer can be determined. Suitable scenes are selected from the browse images and clear air below features is identified by low 532 nm backscatter signal and confirmed by low depolarization and color ratios. The transmittance and two-wavelength techniques are applied to a number of lofted layers and the extinction-to-backscatter ratios are compared with values obtained from the CALIPSO aerosol models [Omar et al., 2004]. The results obtained from these studies are used to adjust the aerosol models and develop observations based extinction-to-backscatter ratio look-up tables and phase functions. Values obtained by these techniques are compared to Sa determinations using other independent methods with a goal of developing probability distribution functions of aerosol type-specific extinction to backscatter ratios. In particular, the results are compared to values determined directly by the High Spectral Resolution Lidar (HSRL) during the CALIPSO CloudSat Validation Experiments (CCVEX) and Sa determined by the application of the two-wavelength lidar Constrained Ratio Aerosol Model-fit (CRAM) retrieval approach [Cattrall et al., 2005; Reagan et al., 2004] to the HSRL data. The results are also compared to values derived using the empirical relationship between the multiple-scattering fraction and the linear depolarization ratio by using Monte Carlo simulations of water clouds [Hu et al., 2006].

  5. How much information do extinction and backscattering measurements contain about the chemical composition of atmospheric aerosol?

    NASA Astrophysics Data System (ADS)

    Kahnert, Michael; Andersson, Emma

    2017-03-01

    We theoretically and numerically investigate the problem of assimilating multiwavelength lidar observations of extinction and backscattering coefficients of aerosols into a chemical transport model. More specifically, we consider the inverse problem of determining the chemical composition of aerosols from these observations. The main questions are how much information the observations contain to determine the particles' chemical composition, and how one can optimize a chemical data assimilation system to make maximum use of the available information. We first quantify the information content of the measurements by computing the singular values of the scaled observation operator. From the singular values we can compute the number of signal degrees of freedom, Ns, and the reduction in Shannon entropy, H. As expected, the information content as expressed by either Ns or H grows as one increases the number of observational parameters and/or wavelengths. However, the information content is strongly sensitive to the observation error. The larger the observation error variance, the lower the growth rate of Ns or H with increasing number of observations. The right singular vectors of the scaled observation operator can be employed to transform the model variables into a new basis in which the components of the state vector can be partitioned into signal-related and noise-related components. We incorporate these results in a chemical data assimilation algorithm by introducing weak constraints that restrict the assimilation algorithm to acting on the signal-related model variables only. This ensures that the information contained in the measurements is fully exploited, but not overused. Numerical tests show that the constrained data assimilation algorithm provides a solution to the inverse problem that is considerably less noisy than the corresponding unconstrained algorithm. This suggests that the restriction of the algorithm to the signal-related model variables suppresses

  6. Analysis of DIAL/HSRL aerosol backscatter and extinction profiles during the SEAC4RS campaign with an aerosol assimilation system

    NASA Astrophysics Data System (ADS)

    Weaver, C. J.; da Silva, A. M., Jr.; Colarco, P. R.; Randles, C. A.

    2015-12-01

    We retrieve aerosol concentrations and optical information from vertical profiles of airborne 532 nm extinction and 532 and 1064 nm backscatter measurements made during the SEAC4RS summer 2013 campaign. The observations are from the High Spectral Resolution Lidar (HSRL) Airborne Differential Absorption Lidar (DIAL) on board the NASA DC-8. Instead of retrieving information about aerosol microphysical properties such as indexes of refraction, we seek information more directly applicable to an aerosol transport model - in our case the Goddard Chemistry Aerosol Radiation and Transport (GOCART) module used in the GEOS-5 Earth modeling system. A joint atmosphere/aerosol mini-reanalysis was performed for the SEAC4RS period using GEOS-5. The meteorological reanalysis followed the MERRA-2 atmospheric reanalysis protocol, and aerosol information from MODIS, MISR, and AERONET provided a constraint on the simulated aerosol optical depth (i.e., total column loading of aerosols). We focus on the simulated concentrations of 10 relevant aerosol species simulated by the GOCART module: dust, sulfate, and organic and black carbon. Our first retrieval algorithm starts with the SEAC4RS mini-reanalysis and adjusts the concentration of each GOCART aerosol species so that differences between the observed and simulated backscatter and extinction measurements are minimized. In this case, too often we are unable to simulate the observations by simple adjustment of the aerosol concentrations. A second retrieval approach adjusts both the aerosol concentrations and the optical parameters (i.e., assigned mass extinction efficiency) associated with each GOCART species. We present results from DC-8 flights over smoke from forest fires over the western US using both retrieval approaches. Finally, we compare our retrieved quantities with in-situ observations of aerosol absorption, scattering, and mass concentrations at flight altitude.

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

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

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

  8. Phase function, backscatter, extinction, and absorption for standard radiation atmosphere and El Chichon aerosol models at visible and near-infrared wavelengths

    NASA Technical Reports Server (NTRS)

    Whitlock, C. H.; Suttles, J. T.; Lecroy, S. R.

    1985-01-01

    Tabular values of phase function, Legendre polynominal coefficients, 180 deg backscatter, and extinction cross section are given for eight wavelengths in the atmospheric windows between 0.4 and 2.2 microns. Also included are single scattering albedo, asymmetry factor, and refractive indices. These values are based on Mie theory calculations for the standard rediation atmospheres (continental, maritime, urban, unperturbed stratospheric, volcanic, upper atmospheric, soot, oceanic, dust, and water-soluble) assest measured volcanic aerosols at several time intervals following the El Chichon eruption. Comparisons of extinction to 180 deg backscatter for different aerosol models are presented and related to lidar data.

  9. Studying the vertical aerosol extinction coefficient by comparing in situ airborne data and elastic backscatter lidar

    NASA Astrophysics Data System (ADS)

    Rosati, Bernadette; Herrmann, Erik; Bucci, Silvia; Fierli, Federico; Cairo, Francesco; Gysel, Martin; Tillmann, Ralf; Größ, Johannes; Gobbi, Gian Paolo; Di Liberto, Luca; Di Donfrancesco, Guido; Wiedensohler, Alfred; Weingartner, Ernest; Virtanen, Annele; Mentel, Thomas F.; Baltensperger, Urs

    2016-04-01

    Vertical profiles of aerosol particle optical properties were explored in a case study near the San Pietro Capofiume (SPC) ground station during the PEGASOS Po Valley campaign in the summer of 2012. A Zeppelin NT airship was employed to investigate the effect of the dynamics of the planetary boundary layer at altitudes between ˜ 50 and 800 m above ground. Determined properties included the aerosol particle size distribution, the hygroscopic growth factor, the effective index of refraction and the light absorption coefficient. The first three parameters were used to retrieve the light scattering coefficient. Simultaneously, direct measurements of both the scattering and absorption coefficient were carried out at the SPC ground station. Additionally, a single wavelength polarization diversity elastic lidar system provided estimates of aerosol extinction coefficients using the Klett method to accomplish the inversion of the signal, for a vertically resolved comparison between in situ and remote-sensing results. Note, however, that the comparison was for the most part done in the altitude range where the overlap function is incomplete and accordingly uncertainties are larger. First, the airborne results at low altitudes were validated with the ground measurements. Agreement within approximately ±25 and ±20 % was found for the dry scattering and absorption coefficient, respectively. The single scattering albedo, ranged between 0.83 and 0.95, indicating the importance of the absorbing particles in the Po Valley region. A clear layering of the atmosphere was observed during the beginning of the flight (until ˜ 10:00 LT - local time) before the mixing layer (ML) was fully developed. Highest extinction coefficients were found at low altitudes, in the new ML, while values in the residual layer, which could be probed at the beginning of the flight at elevated altitudes, were lower. At the end of the flight (after ˜ 12:00 LT) the ML was fully developed, resulting in

  10. Study of MPLNET-Derived Aerosol Climatology over Kanpur, India, and Validation of CALIPSO Level 2 Version 3 Backscatter and Extinction Products

    NASA Technical Reports Server (NTRS)

    Misra, Amit; Tripathi, S. N.; Kaul, D. S.; Welton, Ellsworth J.

    2012-01-01

    The level 2 aerosol backscatter and extinction profiles from the NASA Micropulse Lidar Network (MPLNET) at Kanpur, India, have been studied from May 2009 to September 2010. Monthly averaged extinction profiles from MPLNET shows high extinction values near the surface during October March. Higher extinction values at altitudes of 24 km are observed from April to June, a period marked by frequent dust episodes. Version 3 level 2 Cloud Aerosol Lidar with Orthogonal Polarization (CALIOP) aerosol profile products have been compared with corresponding data from MPLNET over Kanpur for the above-mentioned period. Out of the available backscatter profiles, the16 profiles used in this study have time differences less than 3 h and distances less than 130 km. Among these profiles, four cases show good comparison above 400 m with R2 greater than 0.7. Comparison with AERONET data shows that the aerosol type is properly identified by the CALIOP algorithm. Cloud contamination is a possible source of error in the remaining cases of poor comparison. Another source of error is the improper backscatter-to-extinction ratio, which further affects the accuracy of extinction coefficient retrieval.

  11. Simultaneous measurement of atmospheric temperature, humidity, and aerosol extinction and backscatter coefficients by a combined vibrational pure-rotational Raman lidar

    NASA Astrophysics Data System (ADS)

    Balin, I.; Serikov, I.; Bobrovnikov, S.; Simeonov, V.; Calpini, B.; Arshinov, Y.; van den Bergh, H.

    2004-10-01

    Implementation of the pure-rotational Raman (PRR) lidar method for simultaneous measurement of atmospheric temperature, humidity, and aerosol extinction and backscatter coefficients is reported. The isolation of two wavelength domains of the PRR spectrum and the suppression of the elastically scattered light is carried out by a double-grating polychromator. Experiments involving elastic backscatter from dense clouds and a solid target confirm the high level of suppression of the elastic light in the corresponding acquisition channels of the two selected PRR domains. Calibration of the temperature channel was done both by comparison with an experimentally verified atmospheric temperature model profile and by inter-comparison with radiosondes. Night-time temperature profiles with high vertical resolution were obtained up to the lower stratosphere. The PRR temperature profile combined with the water vapor mixing ratio obtained from the ro-vibrational Raman channel is used to estimate the relative humidity.

  12. Aerosol backscatter studies supporting LAWS

    NASA Technical Reports Server (NTRS)

    Rothermel, Jeffry

    1989-01-01

    Optimized Royal Signals and Radar Establishment (RSRE), Laser True Airspeed System (LATAS) algorithm for low backscatter conditions was developed. The algorithm converts backscatter intensity measurements from focused continuous-wave (CW) airborne Doppler lidar into backscatter coefficients. The performance of optimized algorithm under marginal backscatter signal conditions was evaluated. The 10.6 micron CO2 aerosol backscatter climatologies were statistically analyzed. Climatologies reveal clean background aerosol mode near 10(exp -10)/kg/sq m/sr (mixing ratio units) through middle and upper troposhere, convective mode associated with planetary boundary layer convective activity, and stratospheric mode associated with volcanically-generated aerosols. Properties of clean background mode are critical to design and simulation studies of Laser Atmospheric Wind Sounder (LAWS), a MSFC facility Instrument on the Earth Observing System (Eos). Previous intercomparisons suggested correlation between aerosol backscatter at CO2 wavelength and water vapor. Field measurements of backscatter profiles with MSFC ground-based Doppler lidar system (GBDLS) were initiated in late FY-88 to coincide with independent program of local rawinsonde releases and overflights by Multi-spectral Atmospheric Mapping Sensor (MAMS), a multi-channel infrared radiometer capable of measuring horizontal and vertical moisture distributions. Design and performance simulation studies for LAWS would benefit from the existence of a relationship between backscatter and water vapor.

  13. Raman Lidar Measurements of Aerosol Extinction and Backscattering. Report 2; Derivation of Aerosol Real Refractive Index, Single-Scattering Albedo, and Humidification Factor using Raman Lidar and Aircraft Size Distribution

    NASA Technical Reports Server (NTRS)

    Ferrare, R. A.; Melfi, S. H.; Whiteman, D. N.; Evans, K. D.; Poellot, M.; Kaufman, Y. J.

    1998-01-01

    Aerosol backscattering and extinction profiles measured 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 during two nights in April 1994 are discussed. These profiles are shown to be consistent with the simultaneous aerosol size distribution measurements made by a PCASP (Passive Cavity Aerosol Spectrometer Probe) optical particle counter flown on the University of North Dakota Citation aircraft. We describe a technique which uses both lidar and PCASP measurements to derive the dependence of particle size on relative humidity, the aerosol real refractive index n, and estimate the effective single-scattering albedo Omega(sub 0). Values of n ranged between 1.4-1.5 (dry) and 1.37-1.47 (wet); Omega(sub 0) varied between 0.7 and 1.0. The single-scattering albedo derived from this technique is sensitive to the manner in which absorbing particles are represented in the aerosol mixture; representing the absorbing particles as an internal mixture rather than the external mixture assumed here results in generally higher values of Omega(sub 0). The lidar measurements indicate that the change in particle size with relative humidity as measured by the PCASP can be represented in the form discussed by Hattel with the exponent gamma = 0.3 + or - 0.05. The variations in aerosol optical and physical characteristics captured in the lidar and aircraft size distribution measurements are discussed in the context of the meteorological conditions observed during the experiment.

  14. Extinction and backscatter cross sections of biological materials

    NASA Astrophysics Data System (ADS)

    Thomas, M. E.; Hahn, D. V.; Carr, A. K.; Limsui, D.; Carter, C. C.; Boggs, N. T.; Jackman, J.

    2008-04-01

    Aerosol backscatter and extinction cross-sections are required to model and evaluate the performance of both active and passive detection systems. A method has been developed that begins with laboratory measurements of thin films and suspensions of biological material to obtain the complex index refraction of the biological material from the UV to the LWIR. Using that result with particle size distribution and shape information as inputs to T-matrix or discrete dipole approximation (DDA) calculations yields the extinction cross-section and backscatter cross section as a function of wavelength. These are important inputs to the lidar equation. In a continuing effort to provide validated optical cross-sections, measurements have been made on a number of high purity biological species in the laboratory as well as measurements of material released at recent field tests. The resulting observed differences between laboratory and field measurements aid in distinguishing between intrinsic and extrinsic effects, which can affect the characteristic signatures of important biological aerosols. A variety of biological and test aerosols are examined, including Bacillus atrophaeus (BG), and Erwina, ovalbumin, silica and polystyrene.

  15. Lidar backscattering measurements of background stratospheric aerosols

    NASA Technical Reports Server (NTRS)

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

    1979-01-01

    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.

  16. Aerosol measurement program strategy for global aerosol backscatter model development

    NASA Technical Reports Server (NTRS)

    Bowdle, David A.

    1985-01-01

    The purpose was to propose a balanced program of aerosol backscatter research leading to the development of a global model of aerosol backscatter. Such a model is needed for feasibility studies and systems simulation studies for NASA's prospective satellite-based Doppler lidar wind measurement system. Systems of this kind measure the Doppler shift in the backscatter return from small atmospheric aerosol wind tracers (of order 1 micrometer diameter). The accuracy of the derived local wind estimates and the degree of global wind coverage for such a system are limited by the local availability and by the global scale distribution of natural aerosol particles. The discussions here refer primarily to backscatter model requirements at CO2 wavelengths, which have been selected for most of the Doppler lidar systems studies to date. Model requirements for other potential wavelengths would be similar.

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

    NASA Technical Reports Server (NTRS)

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

    2008-01-01

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

  18. Extinction and backscatter measurements of Antarctic PSC's, 1987: Implications for particle and vapor removal

    NASA Technical Reports Server (NTRS)

    Poole, L. R.; Mccormick, M. Patrick; Browell, Edward V.; Trepte, C. R.; Fahey, D. W.; Kelly, K. K.; Ferry, G. V.; Pueschel, R. F.; Jones, R. L.

    1988-01-01

    The temperature dependence is examined of optical properties measured in the Antarctic during 1987 at the 70 mb level (near 18 km), a level chosen to correlate the results with in situ measurements made from the NASA-Ames ER-2 aircraft during the 1987 Airborne Antarctic Ozone Experiment (AAOE). The data set consists of extinction measurements by Sam 2 inside the Antarctic polar vortex from May to October 1987; and backscatter measurements by the UV-DIAL (Ultraviolet Differential Absorption Lidar) system aboard the Ames DC-8 aircraft during selected AAOE flights. Observed trends are compared with results from a revised version of Pole and McCormick's model to classify the PSC observations by Type (1 or 2) and infer the temporal behavior of the ambient aerosol and ambient vapor mixing ratios. The sample figures show monthly ensembles of the 70-mb Sam 2 extinction ratio (the ratio of aerosol or PSC extinction to molecule extinction) as a function of NMC temperature at the beginning (June) and (October) of the 1987 Antarctic winter. Both ensembles show two rather distinct clusters of points: one oriented in the near vertical direction which depicts the change with temperature of the ambient aerosol extinction ratio; and a second cluster oriented in the near horizontal direction whose position on the vertical scale marks a change in particle phase (i.e., PSC formation) and whose length (the extinction enhancement related to that of the ambient aerosol) is an indicator of PSC type.

  19. Aerosol backscatter lidar calibration and data interpretation

    NASA Technical Reports Server (NTRS)

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

    1984-01-01

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

  20. Intercomparison of aerosol extinction profiles retrieved from MAX-DOAS measurements

    NASA Astrophysics Data System (ADS)

    Frieß, U.; Klein Baltink, H.; Beirle, S.; Clémer, K.; Hendrick, F.; Henzing, B.; Irie, H.; de Leeuw, G.; Li, A.; Moerman, M. M.; van Roozendael, M.; Shaiganfar, R.; Wagner, T.; Wang, Y.; Xie, P.; Yilmaz, S.; Zieger, P.

    2016-07-01

    A first direct intercomparison of aerosol vertical profiles from Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) observations, performed during the Cabauw Intercomparison Campaign of Nitrogen Dioxide measuring Instruments (CINDI) in summer 2009, is presented. Five out of 14 participants of the CINDI campaign reported aerosol extinction profiles and aerosol optical thickness (AOT) as deduced from observations of differential slant column densities of the oxygen collision complex (O4) at different elevation angles. Aerosol extinction vertical profiles and AOT are compared to backscatter profiles from a ceilometer instrument and to sun photometer measurements, respectively. Furthermore, the near-surface aerosol extinction coefficient is compared to in situ measurements of a humidity-controlled nephelometer and dry aerosol absorption measurements. The participants of this intercomparison exercise use different approaches for the retrieval of aerosol information, including the retrieval of the full vertical profile using optimal estimation and a parametrised approach with a prescribed profile shape. Despite these large conceptual differences, and also differences in the wavelength of the observed O4 absorption band, good agreement in terms of the vertical structure of aerosols within the boundary layer is achieved between the aerosol extinction profiles retrieved by the different groups and the backscatter profiles observed by the ceilometer instrument. AOTs from MAX-DOAS and sun photometer show a good correlation (R>0.8), but all participants systematically underestimate the AOT. Substantial differences between the near-surface aerosol extinction from MAX-DOAS and from the humidified nephelometer remain largely unresolved.

  1. Lidar extinction-to-backscatter ratio of the ocean.

    PubMed

    Churnside, James H; Sullivan, James M; Twardowski, Michael S

    2014-07-28

    Bio-optical models are used to develop a model of the lidar extinction-to-backscatter ratio applicable to oceanographic lidar. The model is based on chlorophyll concentration, and is expected to be valid for Case 1 waters. The limiting cases of narrow- and wide-beam lidars are presented and compared with estimates based on in situ optical measurements. Lidar measurements are also compared with the model using in situ or satellite estimates of chlorophyll concentration. A modified lidar ratio is defined, in which the properties of pure sea water are removed. This modified ratio is shown to be nearly constant for wide-beam lidar operating in low-chlorophyll waters, so accurate inversion to derive extinction and backscattering is possible under these conditions. This ratio can also be used for lidar calibration.

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

    PubMed

    Ansmann, A; Wandinger, U; Riebesell, M; Weitkamp, C; Michaelis, W

    1992-11-20

    Height profiles of the extinction and the backscatter coefficients in cirrus clouds are determined independently from elastic- and inelastic- (Raman) backscatter signals. An extended error analysis is given. Examples covering the measured range of extinction-to-backscatter ratios (lidar ratios) in ice clouds are presented. Lidar ratios between 5 and 15 sr are usually found. A strong variation between 2 and 20 sr can be observed within one cloud profile. Particle extinction coefficients determined from inelastic-backscatter signals and from elastic-backscatter signals by using the Klett method are compared. The Klett solution of the extinction profile can be highly erroneous if the lidar ratio varies along the measuring range. On the other hand, simple backscatter lidars can provide reliable information about the cloud optical depth and the mean cloud lidar ratio.

  3. Approach to simultaneously denoise and invert backscatter and extinction from photon-limited atmospheric lidar observations.

    PubMed

    Marais, Willem J; Holz, Robert E; Hu, Yu Hen; Kuehn, Ralph E; Eloranta, Edwin E; Willett, Rebecca M

    2016-10-10

    Atmospheric lidar observations provide a unique capability to directly observe the vertical column of cloud and aerosol scattering properties. Detector and solar-background noise, however, hinder the ability of lidar systems to provide reliable backscatter and extinction cross-section estimates. Standard methods for solving this inverse problem are most effective with high signal-to-noise ratio observations that are only available at low resolution in uniform scenes. This paper describes a novel method for solving the inverse problem with high-resolution, lower signal-to-noise ratio observations that are effective in non-uniform scenes. The novelty is twofold. First, the inferences of the backscatter and extinction are applied to images, whereas current lidar algorithms only use the information content of single profiles. Hence, the latent spatial and temporal information in noisy images are utilized to infer the cross-sections. Second, the noise associated with photon-counting lidar observations can be modeled using a Poisson distribution, and state-of-the-art tools for solving Poisson inverse problems are adapted to the atmospheric lidar problem. It is demonstrated through photon-counting high spectral resolution lidar (HSRL) simulations that the proposed algorithm yields inverted backscatter and extinction cross-sections (per unit volume) with smaller mean squared error values at higher spatial and temporal resolutions, compared to the standard approach. Two case studies of real experimental data are also provided where the proposed algorithm is applied on HSRL observations and the inverted backscatter and extinction cross-sections are compared against the standard approach.

  4. Global Backscatter Experiment (GLOBE) Results: Aerosol Backscatter Global Distribution and Wavelength Dependence

    NASA Technical Reports Server (NTRS)

    Bowdle, David A.

    1992-01-01

    The GLObal Backscatter Experiment (GLOBE) was initiated by NASA in 1986 as an interagency and international research effort to characterize tropospheric backscatter properties. The primary objective of the program is to develop realistic aerosol backscatter inputs for design and simulation studies for NASA's prospective Laser Atmospheric Wind Sounder (LAWS). To achieve this, GLOBE incorporates several different types of aerosol sensors, which operate from a variety of sensor platforms, covering a wide range of spatial and temporal scales, and measure a diverse set of aerosol physical, chemical, and optical properties. The results of this analysis have provided important new information on the life cycles and physicochemical properties of global scale tropospheric aerosol systems. In addition, GLOBE analytical methods will be useful for the Earth Observing System (EOS) and other studies that involve the assimilation of large, complex atmospheric aerosol databases.

  5. Humidity Dependent Extinction of Clay Aerosols

    NASA Astrophysics Data System (ADS)

    Greenslade, M. E.; Attwood, A. R.

    2010-12-01

    Aerosols play an important role in the Earth’s radiative balance by directly scattering and absorbing radiation. The magnitude of aerosol forcing can be altered by changes in relative humidity which cause aerosol size, shape and refractive index to vary. To quantify these effects, a custom cavity ring down instrument operated at 532 nm with two sample channels measures aerosols extinction under dry conditions and at elevated humidity. The optical growth, fRH(ext), is determined as a ratio of the extinction cross section at high relative humidity to that under dry conditions. Three key clay components of mineral dust and mixtures of clay components with ammonium sulfate are investigated using this method. Experimentally obtained optical growth is compared with physical growth factors from the literature and our work determined using several different techniques. Further, Mie theory calculations based on published optical constants are compared with experimental results. Differences between theory and experiment will be discussed.

  6. Use of aerosol microphysical measurements to model IR backscatter in support of GLOBE

    NASA Technical Reports Server (NTRS)

    Patterson, Edward M.; Bowdle, David A.

    1991-01-01

    Data on the concentration and composition of free tropospheric aerosol over the Pacific Ocean, collected during the GAMETAG program in 1977-1978 (Davis, 1980 and Patterson et al., 1980) are used to model values of aerosol optical extinction coefficients (sigma) at two wavelengths (0.55 and 1 micron) and values of volume backscatter coefficients (beta) at four wavelengths (1 micron, 9.11 microns, 9.25 microns, and 10.6 microns) and to investigate the relationship between these parameters. The mass concentrations inferred from the GAMETAG measurements with optical particle spectrometers agreed with the results of simultaneous chemical measurements. The study of the relationships among the optical parameters indicates that visible and near-visible values of beta and sigma may be useful in predicting 9.11- and 10.6-micron backscatter.

  7. Laser remote sensing of tropospheric aerosol over Southern Ireland using a backscatter Raman LIDAR

    NASA Astrophysics Data System (ADS)

    Ruth, Albert A.; Acheson, Karen; Apituley, Arnoud; Chaikovsky, Anatoli; Nicolae, Doina; Ortiz-Amezcua, Pablo; Stoyanov, Dimitar; Trickl, Thomas

    2016-04-01

    Raman backscatter coefficients, extinction coefficients and lidar ratios were measured with a ground based Raman lidar system at University College Cork, Ireland, during the periods of July 2012 - August 2012, April 2013 - December 2013 and March 2014 - May 2014. Statistical analysis of these parameters in this time provided information about seasonal effects of Raman backscatter coefficients and the altitude of the top of the planetary boundary layer. The mean of the altitude of the top of the planetary boundary layer over these time periods is 950 ± 302 m. The values are larger in summer, 1206 ± 367 m, than in winter, 735 m. The altitude of the top of the planetary boundary layer measured at Cork is lower than most EARLINET stations. Raman backscatter coefficients above and altitude of 2 km are highest in summer and spring where the values are greater than 0.28 Mm-1 sr-1. Winter values of Raman backscatter coefficient are less than 0.06 Mm-1 sr-1. These seasonal effects are consistent with most EARLINET stations. Large aerosol loads were detected in July 2013 due to a Canadian forest fire event. HYSPLIT air-mass back trajectory models were used to trace the origin of the detected aerosol layers. The aerosol forecast model, MACC, was used to further investigate and verify the propagation of the smoke. The Lidar ratio values and Klett and Raman backscatter coefficients at Cork, for the 4th July, the 7th to 9th of July and the 11th July were compared with observations at Cabauw, Minsk, Granada, Bucharest, Sofia and Garmisch. Lidar ratio values for the smoke detected at Cork were determined to be between 33 sr and 62 sr. The poster will discuss the seasonal changes of Raman backscatter coefficients and the altitude of the top of the planetary boundary layer at Cork. An investigation of a Canadian forest fire event measured at Cork will be compared with other data from the EARLINET database.

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

    NASA Technical Reports Server (NTRS)

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

    2010-01-01

    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.

  9. Lidar conversion parameters derived from SAGE II extinction measurements

    NASA Technical Reports Server (NTRS)

    Thomason, L. W.; Osborn, M. T.

    1992-01-01

    SAGE II multiwavelength aerosol extinction measurements are used to estimate mass- and extinction-to-backscatter conversion parameters. The basis of the analysis is the principal component analysis of the SAGE II extinction kernels to estimate both total aerosol mass and aerosol backscatter at a variety of wavelengths. Comparisons of coincident SAGE II extinction profiles with 0.694-micron aerosol backscatter profiles demonstrate the validity of the method.

  10. Comparison of SAGE II and lidar stratospheric aerosol extinction datasets after the Mt Pinatubo eruption

    NASA Astrophysics Data System (ADS)

    Antuna Marrero, Juan Carlos

    Both observations and modeling demonstrate that stratospheric aerosols from intense explosive volcanic eruptions cause several different effects on weather and climate. The main effect is the cooling of the earth's surface between one and three years after the eruption. Stratospheric heating, winter warming on the Northern Hemisphere continental areas, ozone depletion and cirrus cloud seeding are several other effects attributed to stratospheric aerosols. Studying the stratospheric aerosol features and their effects on weather and climate requires a precise knowledge of their physical and optical properties. Accurate volcanic climate effects simulations using state of the art general circulation models require detailed and precise information about stratospheric aerosol concentration, distribution in space and time, and optical properties. Satellite aerosol extinction measurements are the main source of information for such studies, however they have gaps because of missing data and time and space coverage. Although lidar aerosol backscattering measurements have been recognized for a long time as a valuable complementary source to the satellite information, they have not been used so far for such a goal. A necessary step for combining both sources of information is the comparison between them, but only very few and limited ones have been conducted. I conducted the most comprehensive comparison ever between lidar and SAGE II aerosol extinction, covering the two and half years after the 1991 Mount Pinatubo eruption. I address the crucial issue of the aerosol extinction variability at the daily scale and I calculated its quantitative magnitudes for the first time. Using both SAGE II coincident sunrise-sunset measurements and lidar measurements one and two days apart I determine it ranges between 50 and 150%. I compared extinction-derived profiles from five lidars with space and time coincident SAGE II extinction measurements. Three lidars are in the tropics and two in

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

    NASA Technical Reports Server (NTRS)

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

    1997-01-01

    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.

  12. Iterative method to determine an averaged backscatter-to-extinction ratio in cirrus clouds.

    PubMed

    Elouragini, S; Flamant, P H

    1996-03-20

    An iterative method to determine an average backscatter-to-extinction ratio and extinction coefficient simultaneously in cirrus clouds is proposed. The method is based on Klett's inversion, which is constrained by the total optical depth. A signal-to-noise ratio greater than 3 at the cloud top is required for an error in the backscatter-to-extinction ratio lower than 20% to result. The method has been tested with simulated lidar signals. An application to an experimental lidar signal is discussed.

  13. Backscatter and extinction measurements in cloud and drizzle at CO2 laser wavelengths

    NASA Technical Reports Server (NTRS)

    Jennings, S. G.

    1986-01-01

    The backscatter and extinction of laboratory generated cloud and drizzle sized water drops were measured at carbon dioxide laser wavelengths (predominately at lambda = 10.591 micrometers). Two distinctly different drop size regimes were studied: one which covers the range normally encompassed by natural cloud droplets and the other representative of mist or drizzle sized drops. The derivation and verification of the relation between extinction and backscatter at carbon dioxide laser wavelengths should allow the determination of large cloud drop and drizzle extinction coefficient solely from a lidar return signal without requiring knowledge of the drop size distribution. This result will also apply to precipitation sized drops so long as they are spherical.

  14. Multiwavelength Comparison of Modeled and Measured Remote Tropospheric Aerosol Backscatter Over Pacific Ocean

    NASA Technical Reports Server (NTRS)

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

    1996-01-01

    Aerosol concentrations and size distributions in the middle and upper troposphere over the remote Pacific Ocean were measured with a forward scattering spectrometer probe (FSSP) on the NASA DC-8 aircraft during NASA's Global Backscatter Experiment (GLOBE) in May-June 1990. The FSSP size channels were recalibrated based on refractive index estimates from flight-level aerosol volatility measurements with a collocated laser optical particle counter (LOPC). The recalibrated FSSP size distributions were averaged over 100-s intervals, fitted with lo-normal distributions and used to calculate aerosol backscatter coefficients at selected wavelengths. The FSSP-derived backscatter estimates were averaged over 300-s intervals to reduce large random fluctuations. The smoothed FSSP aerosol backscatter coefficients were then compared with LOPC-derived backscatter values and with backscatter measured at or near flight level from four lidar systems operating at 0.53, 1.06, 9.11, 9.25, and 10.59 micrometers. Agreement between FSSP-derived and lidar-measured backscatter was generally best at flight level in homogeneous aerosol fields and at high backscatter values. FSSP data often underestimated low backscatter values especially at the longer wavelengths due to poor counting statistics for larger particles (greater than 0.8 micrometers diameter) that usually dominate aerosol backscatter at these wavelengths. FSSP data also underestimated backscatter at shorter wavelengths when particles smaller than the FSSP lower cutoff diameter (0.35 micrometers) made significant contributions to the total backscatter.

  15. Use of aerosol microphysical measurements to model IR backscatter in support of GLOBE

    SciTech Connect

    Patterson, E.M. ); Bowdle, D.A. )

    1991-03-20

    The authors have used the GAMETAG Pacific mid-tropospheric aerosol data set to calculate aerosol optical extinction coefficients ({sigma}) at two wavelengths (0.55 {mu}m and 1 {mu}m) and volume backscatter coefficients ({beta}) at 4 wavelengths (1 {mu}m, 9.11 {mu}m, 9.25 {mu}m, and 10.6 {mu}m). At an altitude of 5 km over the Pacific, northern hemispheric mean values of {beta} for 10.6 {mu} are near 10{sup {minus}10} m{sup {minus}1}sr{sup {minus}1} at an altitude of 5 km, with southern hemispheric values approximately an order of magnitude lower. The 9.11 {mu}m values are roughly a factor of 3 higher than the 10.6 {mu}m values; 9.25 {mu}m values are approximately the same as 9.11 {mu}m values. For the data averaging times of 5-10 min are necessary for the calculated {beta} values as seen by a satellite lidar system. Under the assumptions of this study the molecular form of the sulfate aerosol is not a major determining factor in the calculated {beta} values at 10.6 {mu}m but could be significant at 9.11 {mu}m. A study of relationships among the optical parameters indicates that visible and near-visible values of {beta} and {sigma} may be useful in predicting 9.11- and 10.6 {mu}m backscatter, so that short wavelength aerosol data bases form satellites and Nd-YAG lidars may be useful in extending the data base of direct backscatter measurements at CO{sub 2} wavelengths.

  16. Measurements of Stratospheric Pinatubo Aerosol Extinction Profiles by a Raman Lidar

    NASA Technical Reports Server (NTRS)

    Abo, Makoto; Nagasawa, Chikao

    1992-01-01

    The Raman lidar has been used for remote measurements of water vapor, ozone and atmospheric temperature in the lower troposphere because the Raman cross section is three orders smaller than the Rayleigh cross section. We estimated the extinction coefficients of the Pinatubo volcanic aerosol in the stratosphere using a Raman lidar. If the precise aerosol extinction coefficients are derived, the backscatter coefficient of a Mie scattering lidar will be more accurately estimated. The Raman lidar has performed to measure density profiles of some species using Raman scattering. Here we used a frequency-doubled Nd:YAG laser for transmitter and received nitrogen vibrational Q-branch Raman scattering signal. Ansmann et al. (1990) derived tropospherical aerosol extinction profiles with a Raman lidar. We think that this method can apply to dense stratospheric aerosols such as Pinatubo volcanic aerosols. As dense aerosols are now accumulated in the stratosphere by Pinatubo volcanic eruption, the error of Ramen lidar signal regarding the fluctuation of air density can be ignored.

  17. Extinction-to-Backscatter Ratios of Saharan Dust Layers Derived from In-Situ Measurements and CALIPSO Overflights During NAMMA

    NASA Technical Reports Server (NTRS)

    Omar, Ali H.; Liu, Zhaoyan; Vaughan, Mark A.; Hu, Yongxiang; Ismail, Syed; Powell, Kathleen A.; Winker, David M.; Trepte, Charles R.; Anderson, Bruce E.

    2010-01-01

    We determine the aerosol extinction-to-backscatter (Sa) ratios of dust using airborne in-situ measurements of microphysical properties, and CALIPSO observations during the NASA African Monsoon Multidisciplinary Analyses (NAMMA). The NAMMA field experiment was conducted from Sal, Cape Verde during Aug-Sept 2006. Using CALIPSO measurements of the attenuated backscatter of lofted Saharan dust layers, we apply the transmittance technique to estimate dust Sa ratios at 532 nm and a 2-color method to determine the corresponding 1064 nm Sa. Using this method, we found dust Sa ratios of 39.8 plus or minus 1.4 sr and 51.8 plus or minus 3.6 sr at 532 nm and 1064 nm, respectively. Secondly, Sa ratios at both wavelengths is independently calculated using size distributions measured aboard the NASA DC-8 and estimates of Saharan dust complex refractive indices applied in a T-Matrix scheme. We found Sa ratios of 39.1 plus or minus 3.5 sr and 50.0 plus or minus 4 sr at 532 nm and 1064 nm, respectively, using the T-Matrix calculations applied to measured size spectra. Finally, in situ measurements of the total scattering (550 nm) and absorption coefficients (532 nm) are used to generate an extinction profile that is used to constrain the CALIPSO 532 nm extinction profile.

  18. Ozone and Aerosol Retrieval from Backscattered Ultraviolet Radiation

    NASA Technical Reports Server (NTRS)

    Bhartia, Pawan K.

    2004-01-01

    In this presentation we will discuss the techniques to estimate total column ozone and aerosol absorption optical depth from the measurements of backscattered ultraviolet (buv) radiation. The total ozone algorithm has been used to create a unique record of the ozone layer, spanning more than 3 decades, from a series of instruments (BUV, SBUV, TOMS, SBUV/2) flown on NASA, NOAA, Japanese and Russian satellites. We will discuss how this algorithm can be considered a generalization of the well-known Dobson/Brewer technique that has been used to process data from ground-based instruments for many decades, and how it differs from the DOAS techniques that have been used to estimate vertical column densities of a host of trace gases from data collected by GOME and SCIAMACHY instruments. The BUV aerosol algorithm is most suitable for the detection of UV absorbing aerosols (smoke, desert dust, volcanic ash) and is the only technique that can detect aerosols embedded in clouds. This algorithm has been used to create a quarter century record of aerosol absorption optical depth using the BUV data collected by a series of TOMS instruments. We will also discuss how the data from the OM1 instrument launched on July 15,2004 will be combined with data from MODIS and CALIPSO lidar data to enhance the accuracy and information content of satellite-derived aerosol measurements. The OM1 and MODIS instruments are currently flying on EOS Aura and EOS Aqua satellites respectively, part of a constellation of satellites called the "A-train". The CALIPSO satellite is expected to join this constellation in mid 2005.

  19. On deriving the accurate aerosol extinction profiles in the troposphere and lower stratosphere using the range dependent scattering ratio

    NASA Astrophysics Data System (ADS)

    Satyanarayana, M. V.; Radhakrishnan, S. R.; Mahadevanpillai, V. P.; Krishnakumar, V.

    2008-12-01

    Lidar has proven to be an effective instrument for obtaining high resolution profiles of atmospheric aerosols. Deriving the optical properties of aerosols from the experimentally obtained lidar data is one of the most interesting and challenging task for the atmospheric scientists. A few methods had been developed so far, to obtain the quantitative profiles of extinction and backscattering coefficient of aerosols from the pulsed backscattering lidar measurements. Most of the existing inversion methods assume a range independent value for the scattering ratio for inverting the lidar signal even though it is known that the scattering ratio depends on the nature of aerosols and as such range dependent. We used a modified Klett's method for the inversion of lidar signal that uses range dependent scattering ratio (s) for the characterization of atmospheric aerosols. This method provides the constants k and s for all the altitude regions of the atmosphere and leads to derive the aerosol extinction profile for the lidar data. In this paper we made a study on the errors involved in the extinction profiles derived using the range dependent scattering ratio and discuss the approach in this regard to obtain the accurate extinction profiles.

  20. Application of the two-stream inversion algorithm for retrieval of extinction, backscatter, and lidar ratio for clean and polluted Arctic air

    NASA Astrophysics Data System (ADS)

    Stachlewska, Iwona S.; Christoph, Ritter; Neuber, Roland

    2005-10-01

    The background aerosol conditions and the conditions contaminated with aerosol of antropogenic origin (Arctic haze) were investigated during two Arctic campaigns, the Arctic Study of Tropospheric Aerosols, Clouds and Radiation (ASTAR) in 2004 and Svalbard Experiment (SVALEX) in 2005, respectively. Results obtained by application of the two-stream inversion algorithm to the elastic lidar signals measured on two days representative for each campaign are presented. The calculations were done using signals obtained by the nadir-looking Airborne Mobile Aerosol Lidar (AMALi) probing lower troposphere from the AWI research aircraft Polar 2 overflying the stationary Koldewey Aerosol Raman Lidar (KARL) based at the AWI Koldewey Research Station in Ny Ålesund, Svalbard. The method allowed independent retrieval of extinction and backscatter coefficient profiles and lidar ratio profiles for each of the two days representative for both clean and polluted lower troposphere in Arctic.

  1. Mount St. Helens related aerosol properties from solar extinction measurements

    SciTech Connect

    Michalsky, J.J.; Kleckner, E.W.; Stokes, G.M.

    1980-11-01

    The optical extinction due to the introduction of aerosols and aerosol-precursors into the troposphere and stratosphere during the major eruptive phase of Mount St. Helens, Washington, is quantified. The concentration is on the two-week period centered on the major eruption of 22 July 1980. (ACR)

  2. The deconvolution of aerosol backscattered optical pulses to obtain system-independent aerosol signatures

    NASA Astrophysics Data System (ADS)

    McGuire, D.; Conner, M.

    1981-06-01

    Means are discussed for extracting system-independent aerosol signatures from aerosol backscatter measurements obtained with a specific pencil beam active optical detection system. Such signatures are required before the backscatter data can be applied to various proposed optical fuze designs for determining their aerosol vulnerability and to the investigation of aerosol discrimination schemes. The measurement system, which has been used in numerous experiments to probe such aerosols as weather clouds and military smokes, is a short pulse GaAs laser probe (pulse width + or - 10 nanoseconds whose range sensitivity extends from near the system to beyond 10 meters. A computationally fast numerical deconvolution algorithm is devised together with a comprehensive supporting analysis. Both indicate that severe signal-to-noise ratio constraints apply to the achievement of meaningful superresolution. While the signal-to-noise ratios typical of recent measurements are likely to satisfy the severe constraints discovered, many of the earlier data are too noisy and thus require other signature determination methods.

  3. Broadband measurements of aerosol extinction in the ultraviolet spectral region

    NASA Astrophysics Data System (ADS)

    Washenfelder, R. A.; Flores, J. M.; Brock, C. A.; Brown, S. S.; Rudich, Y.

    2013-01-01

    Aerosols influence the Earth's radiative budget by scattering and absorbing incoming solar radiation. The optical properties of aerosols vary as a function of wavelength, but few measurements have reported the wavelength dependence of aerosol extinction cross-sections and complex refractive indices. We describe a new laboratory instrument to measure aerosol optical extinction as a function of wavelength, using cavity enhanced spectroscopy with a broadband light source. The instrument consists of two broadband channels which span the 360-390 and 385-420 nm spectral regions using two light emitting diodes (LED) and a grating spectrometer with charge-coupled device (CCD) detector. We determined aerosol extinction cross-sections and directly observed Mie scattering resonances for aerosols that are purely scattering (polystyrene latex spheres and ammonium sulfate), slightly absorbing (Suwannee River fulvic acid), and strongly absorbing (nigrosin dye). We describe an approach for retrieving refractive indices as a function of wavelength from the measured extinction cross-sections over the 360-420 nm wavelength region. The retrieved refractive indices for PSL and ammonium sulfate agree within uncertainty with literature values for this spectral region. The refractive index determined for nigrosin is 1.78 (±0.03) + 0.19 (±0.08) i at 360 nm and 1.53 (±0.03) + 0.21 (±0.05) i at 420 nm. The refractive index determined for Suwannee River fulvic acid is 1.71 (±0.02) + 0.07 (±0.06) i at 360 nm and 1.66 (±0.02) + 0.06 (±0.04) i at 420 nm. These laboratory results support the potential for a field instrument capable of determining ambient aerosol optical extinction, average aerosol extinction cross-section, and complex refractive index as a function of wavelength.

  4. Broadband measurements of aerosol extinction in the ultraviolet spectral region

    NASA Astrophysics Data System (ADS)

    Washenfelder, R. A.; Flores, J. M.; Brock, C. A.; Brown, S. S.; Rudich, Y.

    2013-04-01

    Aerosols influence the Earth's radiative budget by scattering and absorbing incoming solar radiation. The optical properties of aerosols vary as a function of wavelength, but few measurements have reported the wavelength dependence of aerosol extinction cross sections and complex refractive indices. We describe a new laboratory instrument to measure aerosol optical extinction as a function of wavelength, using cavity enhanced spectroscopy with a broadband light source. The instrument consists of two broadband channels which span the 360-390 and 385-420 nm spectral regions using two light emitting diodes (LED) and a grating spectrometer with charge-coupled device (CCD) detector. We determined aerosol extinction cross sections and directly observed Mie scattering resonances for aerosols that are purely scattering (polystyrene latex spheres and ammonium sulfate), slightly absorbing (Suwannee River fulvic acid), and strongly absorbing (nigrosin dye). We describe an approach for retrieving refractive indices as a function of wavelength from the measured extinction cross sections over the 360-420 nm wavelength region. The retrieved refractive indices for PSL and ammonium sulfate agree within uncertainty with the literature values for this spectral region. The refractive index determined for nigrosin is 1.78 (± 0.03) + 0.19 (± 0.08)i at 360 nm and 1.63 (± 0.03) + 0.21 (± 0.05)i at 420 nm. The refractive index determined for Suwannee River fulvic acid is 1.71 (± 0.02) + 0.07 (± 0.06)i at 360 nm and 1.66 (± 0.02) + 0.06 (± 0.04)i at 420 nm. These laboratory results support the potential for a field instrument capable of determining ambient aerosol optical extinction, average aerosol extinction cross section, and complex refractive index as a function of wavelength.

  5. Extinction-to-Backscatter Ratios of Saharan Dust Layers Derived from In-Situ Measurements and CALIPSO Overflights During NAMMA

    NASA Technical Reports Server (NTRS)

    Omar, Ali H.; Liu, Zhaoyan; Vaughan, Mark A.; Thornhill, Kenneth L., II; Kittaka, Chieko; Ismail, Syed; Chen, Gao; Powell, Kathleen A.; Winker, David M.; Trepte, Charles R.; Trepte, Charles R.; Winstead, Edward L.; Anderson, Bruce E.

    2010-01-01

    We determine the extinction-to-backscatter (Sa) ratios of dust using (1) airborne in-situ measurements of microphysical properties, (2) modeling studies, and (3) the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) observations recorded during the NASA African Monsoon Multidisciplinary Analyses (NAMMA) field experiment conducted from Sal, Cape Verde during Aug-Sept 2006. Using CALIPSO measurements of the attenuated backscatter of lofted Saharan dust layers, we apply the transmittance technique to estimate dust Sa ratios at 532 nm and a 2-color method to determine the corresponding 1064 nm Sa. This method yielded dust Sa ratios of 39.8 plus or minus 1.4 sr and 51.8 plus or minus 3.6 sr at 532 nm and 1064 nm, respectively. Secondly, Sa at both wavelengths is independently calculated using size distributions measured aboard the NASA DC-8 and estimates of Saharan dust complex refractive indices applied in a T-Matrix scheme. We found Sa ratios of 39.1 plus or minus 3.5 sr and 50.0 plus or minus 4 sr at 532 nm and 1064 nm, respectively, using the T-Matrix calculations applied to measured size spectra. Finally, in situ measurements of the total scattering (550 nm) and absorption coefficients (532 nm) are used to generate an extinction profile that is used to constrain the CALIPSO 532 nm extinction profile and thus generate a stratified 532 nm Sa. This method yielded an Sa ratio at 532 nm of 35.7 sr in the dust layer and 25 sr in the marine boundary layer consistent with a predominantly seasalt aerosol near the ocean surface. Combinatorial simulations using noisy size spectra and refractive indices were used to estimate the mean and uncertainty (one standard deviation) of these Sa ratios. These simulations produced a mean (plus or minus uncertainty) of 39.4 (plus or minus 5.9) sr and 56.5 (plus or minus 16.5) sr at 532 nm and 1064 nm, respectively, corresponding to percent uncertainties of 15% and 29%. These results will provide a measurements

  6. An Accuracy Assessment of the CALIOP/CALIPSO Version 2/Version 3 Daytime Aerosol Extinction Product Based on a Detailed Multi-Sensor, Multi-Platform Case Study

    NASA Technical Reports Server (NTRS)

    Kacenelenbogen, M.; Vaughan, M. A.; Redemann, J.; Hoff, R. M.; Rogers, R. R.; Ferrare, R. A.; Russell, P. B.; Hostetler, C. A.; Hair, J. W.; Holben, B. N.

    2011-01-01

    The Cloud Aerosol LIdar with Orthogonal Polarization (CALIOP), on board the CALIPSO platform, has measured profiles of total attenuated backscatter coefficient (level 1 products) since June 2006. CALIOP s level 2 products, such as the aerosol backscatter and extinction coefficient profiles, are retrieved using a complex succession of automated algorithms. The goal of this study is to help identify potential shortcomings in the CALIOP version 2 level 2 aerosol extinction product and to illustrate some of the motivation for the changes that have been introduced in the next version of CALIOP data (version 3, released in June 2010). To help illustrate the potential factors contributing to the uncertainty of the CALIOP aerosol extinction retrieval, we focus on a one-day, multi-instrument, multiplatform comparison study during the CALIPSO and Twilight Zone (CATZ) validation campaign on 4 August 2007. On that day, we observe a consistency in the Aerosol Optical Depth (AOD) values recorded by four different instruments (i.e. spaceborne MODerate Imaging Spectroradiometer, MODIS: 0.67 and POLarization and Directionality of Earth s Reflectances, POLDER: 0.58, airborne High Spectral Resolution Lidar, HSRL: 0.52 and ground-based AErosol RObotic NETwork, AERONET: 0.48 to 0.73) while CALIOP AOD is a factor of two lower (0.32 at 532 nm). This case study illustrates the following potential sources of uncertainty in the CALIOP AOD: (i) CALIOP s low signal-to-noise ratio (SNR) leading to the misclassification and/or lack of aerosol layer identification, especially close to the Earth s surface; (ii) the cloud contamination of CALIOP version 2 aerosol backscatter and extinction profiles; (iii) potentially erroneous assumptions of the aerosol extinction-to-backscatter ratio (Sa) used in CALIOP s extinction retrievals; and (iv) calibration coefficient biases in the CALIOP daytime attenuated backscatter coefficient profiles. The use of version 3 CALIOP extinction retrieval for our case

  7. An accuracy assessment of the CALIOP/CALIPSO version 2/version 3 daytime aerosol extinction product based on a detailed multi-sensor, multi-platform case study

    NASA Astrophysics Data System (ADS)

    Kacenelenbogen, M.; Vaughan, M. A.; Redemann, J.; Hoff, R. M.; Rogers, R. R.; Ferrare, R. A.; Russell, P. B.; Hostetler, C. A.; Hair, J. W.; Holben, B. N.

    2011-04-01

    The Cloud Aerosol LIdar with Orthogonal Polarization (CALIOP), on board the CALIPSO platform, has measured profiles of total attenuated backscatter coefficient (level 1 products) since June 2006. CALIOP's level 2 products, such as the aerosol backscatter and extinction coefficient profiles, are retrieved using a complex succession of automated algorithms. The goal of this study is to help identify potential shortcomings in the CALIOP version 2 level 2 aerosol extinction product and to illustrate some of the motivation for the changes that have been introduced in the next version of CALIOP data (version 3, released in June 2010). To help illustrate the potential factors contributing to the uncertainty of the CALIOP aerosol extinction retrieval, we focus on a one-day, multi-instrument, multiplatform comparison study during the CALIPSO and Twilight Zone (CATZ) validation campaign on 4 August 2007. On that day, we observe a consistency in the Aerosol Optical Depth (AOD) values recorded by four different instruments (i.e. space-borne MODerate Imaging Spectroradiometer, MODIS: 0.67 and POLarization and Directionality of Earth's Reflectances, POLDER: 0.58, airborne High Spectral Resolution Lidar, HSRL: 0.52 and ground-based AErosol RObotic NETwork, AERONET: 0.48 to 0.73) while CALIOP AOD is a factor of two lower (0.32 at 532 nm). This case study illustrates the following potential sources of uncertainty in the CALIOP AOD: (i) CALIOP's low signal-to-noise ratio (SNR) leading to the misclassification and/or lack of aerosol layer identification, especially close to the Earth's surface; (ii) the cloud contamination of CALIOP version 2 aerosol backscatter and extinction profiles; (iii) potentially erroneous assumptions of the aerosol extinction-to-backscatter ratio (Sa) used in CALIOP's extinction retrievals; and (iv) calibration coefficient biases in the CALIOP daytime attenuated backscatter coefficient profiles. The use of version 3 CALIOP extinction retrieval for our case

  8. Vertical Aerosol Backscatter Variability from an Airborne Focused Continuous Wave CO2 Lidar

    NASA Technical Reports Server (NTRS)

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

    1998-01-01

    Atmospheric aerosol backscatter measurements using a continuous wave focused Doppler lidar at 9.1 micron wavelength were obtained over western North America and the Pacific Ocean during 13 - 26 September, 1995 as part of National Aeronautics and Space Administration's (NASA) Multi-center Airborne Coherent Atmospheric Wind Sensor (MACAWS) mission on board the NASA DC8 aircraft. Backscatter variability was measured for approximately 52 flight hours, covering equivalent horizontal distance of approximately 25,000 km in the troposphere. Quasi-vertical backscatter profiles were also obtained during various ascents and descents which ranged between approximately 0.1 to 12.0 km altitude. Aerosol haze layers were encountered at different altitudes. Similarities and differences for aerosol loading over land and over ocean were observed. A mid-tropospheric aerosol backscatter background mode was found with modal value approximately 1O(exp -10)/m/sr, consistent with previous airborne and ground-based datasets.

  9. Interpretation of solar extinction data for stratospheric aerosols

    NASA Technical Reports Server (NTRS)

    Pepin, T. J.

    1980-01-01

    This paper discusses the inversion problem for aerosols using the solar extinction method. A series of numerical experiments is described in which solar extinction measurement systems are modeled. A numerical model of a solar extinction measurement system has been coupled with model atmospheres that exhibit fine scale structures to produce numerically generated data signals. These signals were then inverted to study the effect that measurement errors and desired vertical resolution produce in the inverted results. Knowledge o2 the trade off between vertical resolution and the accuracy of inversion aid in the interpretation of the inverted results.

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

    NASA Technical Reports Server (NTRS)

    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

    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.

  11. Recent Improvements to CALIOP Level 3 Aerosol Profile Product for Global 3-D Aerosol Extinction Characterization

    NASA Astrophysics Data System (ADS)

    Tackett, J. L.; Getzewich, B. J.; Winker, D. M.; Vaughan, M. A.

    2015-12-01

    With nine years of retrievals, the CALIOP level 3 aerosol profile product provides an unprecedented synopsis of aerosol extinction in three dimensions and the potential to quantify changes in aerosol distributions over time. The CALIOP level 3 aerosol profile product, initially released as a beta product in 2011, reports monthly averages of quality-screened aerosol extinction profiles on a uniform latitude/longitude grid for different cloud-cover scenarios, called "sky conditions". This presentation demonstrates improvements to the second version of the product which will be released in September 2015. The largest improvements are the new sky condition definitions which parse the atmosphere into "cloud-free" views accessible to passive remote sensors, "all-sky" views accessible to active remote sensors and "cloudy-sky" views for opaque and transparent clouds which were previously inaccessible to passive remote sensors. Taken together, the new sky conditions comprehensively summarize CALIOP aerosol extinction profiles for a broad range of scientific queries. In addition to dust-only extinction profiles, the new version will include polluted-dust and smoke-only extinction averages. A new method is adopted for averaging dust-only extinction profiles to reduce high biases which exist in the beta version of the level 3 aerosol profile product. This presentation justifies the new averaging methodology and demonstrates vertical profiles of dust and smoke extinction over Africa during the biomass burning season. Another crucial advancement demonstrated in this presentation is a new approach for computing monthly mean aerosol optical depth which removes low biases reported in the beta version - a scenario unique to lidar datasets.

  12. A new high spectral resolution lidar technique for direct retrievals of cloud and aerosol extinction

    NASA Astrophysics Data System (ADS)

    Yorks, J. E.; McGill, M. J.; Hlavka, D. L.

    2014-12-01

    The Airborne Cloud-Aerosol Transport System (ACATS) is a Doppler lidar system and high spectral resolution lidar (HSRL) recently developed at NASA Goddard Space Flight Center (GSFC). ACATS passes the returned atmospheric backscatter through a single etalon and divides the transmitted signal into several channels (wavelength intervals), which are measured simultaneously and independently (Figure 1). Both the particulate and molecular scattered signal can be directly and unambiguously measured, allowing for direct retrievals of particle extinction. The broad Rayleigh-scattered spectrum is imaged as a nearly flat background, illustrated in Figure 1c. The integral of the particulate backscattered spectrum is analogous to the aerosol measurement from the typical absorption filter HSRL technique in that the molecular and particulate backscatter components can be separated (Figure 1c and 1d). The main difference between HSRL systems that use the iodine filter technique and the multichannel etalon technique used in the ACATS instrument is that the latter directly measures the spectral broadening of the particulate backscatter using the etalon to filter out all backscattered light with the exception of a narrow wavelength interval (1.5 picometers for ACATS) that contains the particulate spectrum (grey, Figure 1a). This study outlines the method and retrieval algorithms for ACATS data products, focusing on the HSRL derived cloud and aerosol properties. While previous ground-based multi-channel etalon systems have been built and operated for wind retrievals, there has been no airborne demonstration of the technique and the method has not been used to derive HSRL cloud and aerosol properties. ACATS has flown on the NASA ER-2 during flights over Alaska in July 2014 and as part of the Wallops Airborne Vegetation Experiment (WAVE) in September 2012. This study will focus on the HSRL aspect of the ACATS instrument, since the method and retrieval algorithms have direct application

  13. Visible and near infrared observation on the Global Aerosol Backscatter Experiment (GLOBE)

    NASA Technical Reports Server (NTRS)

    Spinhirne, James D.; Cavanaugh, John F.; Chudamani, S.; Bufton, Jack L.; Sullivan, Robert J.

    1991-01-01

    The Global Aerosol Backscatter Experiment (GLOBE) was intended to provide data on prevailing values of atmospheric backscatter cross-section. The primary intent was predicting the performance of spaceborne lidar systems, most notably the Laser Atmospheric Wind Sounder (LAWS) for the Earth Observing System (EOS). The second and related goal was to understand the source and characteristics of atmospheric aerosol particles. From the GLOBE flights, extensive data was obtained on the structure of clouds and the marine planetary boundary layer. A notable result for all observations is the consistency of the large increases in the aerosol scattering ratio for the marine boundary layer. Other results are noted.

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

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

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

  15. The change of depolarization of backscattering light from the polar stratospheric aerosol layer

    NASA Technical Reports Server (NTRS)

    Iwasaka, Y.

    1985-01-01

    The change of polarization properties of scattered light strongly depends on the non-spherisity of target particles. It should be helpful information for the study of stratospheric aerosols to know the non-spherisity of stratospheric aerosol particles. The change of the total backscatter depolarization ratio of the stratospheric aerosol layer measured at Syowa Station (69.00 deg S, 39.35 deg E), Antarctica is described.

  16. Improvement of Raman lidar algorithm for quantifying aerosol extinction

    NASA Technical Reports Server (NTRS)

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

    2005-01-01

    Aerosols are particles of different composition and origin and influence the formation of clouds which are important in atmospheric radiative balance. At the present there is high uncertainty on the effect of aerosols on climate and this is mainly due to the fact that aerosol presence in the atmosphere can be highly variable in space and time. Monitoring of the aerosols in the atmosphere is necessary to better understanding many of these uncertainties. A lidar (an instrument that uses light to detect the extent of atmospheric aerosol loading) can be particularly useful to monitor aerosols in the atmosphere since it is capable to record the scattered intensity as a function of altitude from molecules and aerosols. One lidar method (the Raman lidar) makes use of the different wavelength changes that occur when light interacts with the varying chemistry and structure of atmospheric aerosols. One quantity that is indicative of aerosol presence is the aerosol extinction which quantifies the amount of attenuation (removal of photons), due to scattering, that light undergoes when propagating in the atmosphere. It can be directly measured with a Raman lidar using the wavelength dependence of the received signal. In order to calculate aerosol extinction from Raman scattering data it is necessary to evaluate the rate of change (derivative) of a Raman signal with respect to altitude. Since derivatives are defined for continuous functions, they cannot be performed directly on the experimental data which are not continuous. The most popular technique to find the functional behavior of experimental data is the least-square fit. This procedure allows finding a polynomial function which better approximate the experimental data. The typical approach in the lidar community is to make an a priori assumption about the functional behavior of the data in order to calculate the derivative. It has been shown in previous work that the use of the chi-square technique to determine the most

  17. Microphysical particle parameters from extinction and backscatter lidar data by inversion with regularization: theory.

    PubMed

    Müller, D; Wandinger, U; Ansmann, A

    1999-04-20

    A method is proposed that permits one to retrieve physical parameters of tropospheric particle size distributions, e.g., effective radius, volume, surface-area, and number concentrations, as well as the mean complex refractive index on a routine basis from backscatter and extinction coefficients at multiple wavelengths. The optical data in terms of vertical profiles are derived from multiple-wavelength lidar measurements at 355, 400, 532, 710, 800, and 1064 nm for backscatter data and 355 and 532 nm for extinction data. The algorithm is based on the concept of inversion with regularization. Regularization is performed by generalized cross-validation. This method does not require knowledge of the shape of the particle size distribution and can handle measurement errors of the order of 20%. It is shown that at least two extinction data are necessary to retrieve the particle parameters to an acceptable accuracy. Simulations with monomodal and bimodal logarithmic-normal size distributions show that it is possible to derive effective radius, volume, and surface-area concentrations to an accuracy of +/-50%, the real part of the complex refractive index to +/-0.05, and the imaginary part to +/-50%. Number concentrations may have errors larger than +/-50%.

  18. Applications of Sunphotometry to Aerosol Extinction and Surface Anisotropy

    SciTech Connect

    Tsay, S.

    2002-09-30

    Support cost-sharing of a newly developed sunphotometer in field deployment for aerosol studies. This is a cost-sharing research to deploy a newly developed sun-sky-surface photometer for studying aerosol extinction and surface anisotropy at the ARM SGP, TWP, and NSA-AAO CART sites and in many field campaigns. Atmospheric aerosols affect the radiative energy balance of the Earth, both directly by perturbing the incoming/outgoing radiation fields and indirectly by influencing the properties/processes of clouds and reactive greenhouse gases. The surface bidirectional reflectance distribution function (BRDF) also plays a crucial role in the radiative energy balance, since the BRDF is required to determine (i) the spectral and spectrally-averaged surface albedo, and (ii) the top-of-the-atmosphere (TOA) angular distribution of radiance field. Therefore, the CART sites provide an excellent, albeit unique, opportunity to collect long-term climatic data in characterizing aerosol properties and various types of surface anisotropy.

  19. Applications of Sunphotometry to Aerosol Extinction and Surface Anisotropy

    NASA Technical Reports Server (NTRS)

    Tsay, S. C.; Holben, B. N.; Privette, J. L.

    2005-01-01

    Support cost-sharing of a newly developed sunphotometer in field deployment for aerosol studies. This is a cost-sharing research to deploy a newly developed sun-sky-surface photometer for studying aerosol extinction and surface anisotropy at the ARM SGP, TWP, and NSA-AAO CART sites and in many field campaigns. Atmospheric aerosols affect the radiative energy balance of the Earth, both directly by perturbing the incoming/outgoing radiation fields and indirectly by influencing the properties/processes of clouds and reactive greenhouse gases. The surface bidirectional reflectance distribution function (BRDF) also plays a crucial role in the radiative energy balance, since the BRDF is required to determine (1) the spectral and spectrally-averaged surface albedo, and (2) the top-of-the-atmosphere (TOA) angular distribution of radiance field. Therefore, the CART sites provide an excellent, albeit unique, opportunity to collect long-term climatic data in characterizing aerosol properties and various types of surface anisotropy.

  20. Improving the detection of wind fields from LIDAR aerosol backscatter using feature extraction

    NASA Astrophysics Data System (ADS)

    Bickel, Brady R.; Rotthoff, Eric R.; Walters, Gage S.; Kane, Timothy J.; Mayor, Shane D.

    2016-04-01

    The tracking of winds and atmospheric features has many applications, from predicting and analyzing weather patterns in the upper and lower atmosphere to monitoring air movement from pig and chicken farms. Doppler LIDAR systems exist to quantify the underlying wind speeds, but cost of these systems can sometimes be relatively high, and processing limitations exist. The alternative is using an incoherent LIDAR system to analyze aerosol backscatter. Improving the detection and analysis of wind information from aerosol backscatter LIDAR systems will allow for the adoption of these relatively low cost instruments in environments where the size, complexity, and cost of other options are prohibitive. Using data from a simple aerosol backscatter LIDAR system, we attempt to extend the processing capabilities by calculating wind vectors through image correlation techniques to improve the detection of wind features.

  1. Aerosol and Light Extinction Databases for North America and Europe

    DTIC Science & Technology

    1992-06-10

    Light Extinction Database ........................................... 5 2.3 NPS - NFPN Aerosol Chemestry Database...E. Wilson of U.S. Environmental Protection Agency, co-operative agreement # CR-81-5727-02-0. His help is greatly appreciated. The NESCAUM data were...Environment 11: 803-812. 8. EPA Report to Congress, 1979. Protecting Visibility. Environmental Protection Agency, Report No. EPA-450/5-79-008. 9. Husar, R. B

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

    NASA Technical Reports Server (NTRS)

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

    1986-01-01

    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.

  3. Aerosol and cloud observations with a CO2 backscatter lidar on the NASA DC-8 GLOBE Pacific Missions

    NASA Technical Reports Server (NTRS)

    Menzies, Robert T.; Tratt, David M.

    1991-01-01

    The paper presents an airborne backscatter lidar developed to fly multiple times on the NASA DC-8 research aircraft and measure vertical profiles of aerosol and cloud backscatter throughout the vertical extent of the troposphere, with emphasis on coverage of the range of latitudes. The lidar instrument characteristics are summarized and the calibration procedures are described. Results of aerosol and cloud observations are presented.

  4. Stand-off detection of aerosols using mid-infrared backscattering Fourier transform spectroscopy

    NASA Astrophysics Data System (ADS)

    Maidment, L.; Zhang, Z.; Bowditch, M. D.; Howle, C. R.; Reid, D. T.

    2016-10-01

    The spectrum of mid-infrared light scattered from an actively illuminated aerosol was used to distinguish between different chemicals. Using spectrally broad illumination from an optical parametric oscillator covering 3.2 - 3.55 μm, characteristic absorption features of two different chemicals were detected, and two similar molecules were clearly distinguished using the spectra of backscattered light from each chemical aerosol.

  5. Comparisons of aerosol backscatter using satellite and ground lidars: implications for calibrating and validating spaceborne lidar

    NASA Astrophysics Data System (ADS)

    Gimmestad, Gary; Forrister, Haviland; Grigas, Tomas; O’Dowd, Colin

    2017-02-01

    The Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) instrument on the polar orbiter Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) is an elastic backscatter lidar that produces a global uniformly-calibrated aerosol data set. Several Calibration/Validation (Cal/Val) studies for CALIOP conducted with ground-based lidars and CALIOP data showed large aerosol profile disagreements, both random and systematic. In an attempt to better understand these problems, we undertook a series of ground-based lidar measurements in Atlanta, Georgia, which did not provide better agreement with CALIOP data than the earlier efforts, but rather prompted us to investigate the statistical limitations of such comparisons. Meaningful Cal/Val requires intercomparison data sets with small enough uncertainties to provide a check on the maximum expected calibration error. For CALIOP total attenuated backscatter, reducing the noise to the required level requires averaging profiles along the ground track for distances of at least 1,500 km. Representative comparison profiles often cannot be acquired with ground-based lidars because spatial aerosol inhomogeneities introduce systematic error into the averages. These conclusions have implications for future satellite lidar Cal/Val efforts, because planned satellite lidars measuring aerosol backscatter, wind vector, and CO2 concentration profiles may all produce data requiring considerable along-track averaging for meaningful Cal/Val.

  6. Comparisons of aerosol backscatter using satellite and ground lidars: implications for calibrating and validating spaceborne lidar.

    PubMed

    Gimmestad, Gary; Forrister, Haviland; Grigas, Tomas; O'Dowd, Colin

    2017-02-15

    The Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) instrument on the polar orbiter Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) is an elastic backscatter lidar that produces a global uniformly-calibrated aerosol data set. Several Calibration/Validation (Cal/Val) studies for CALIOP conducted with ground-based lidars and CALIOP data showed large aerosol profile disagreements, both random and systematic. In an attempt to better understand these problems, we undertook a series of ground-based lidar measurements in Atlanta, Georgia, which did not provide better agreement with CALIOP data than the earlier efforts, but rather prompted us to investigate the statistical limitations of such comparisons. Meaningful Cal/Val requires intercomparison data sets with small enough uncertainties to provide a check on the maximum expected calibration error. For CALIOP total attenuated backscatter, reducing the noise to the required level requires averaging profiles along the ground track for distances of at least 1,500 km. Representative comparison profiles often cannot be acquired with ground-based lidars because spatial aerosol inhomogeneities introduce systematic error into the averages. These conclusions have implications for future satellite lidar Cal/Val efforts, because planned satellite lidars measuring aerosol backscatter, wind vector, and CO2 concentration profiles may all produce data requiring considerable along-track averaging for meaningful Cal/Val.

  7. Comparisons of aerosol backscatter using satellite and ground lidars: implications for calibrating and validating spaceborne lidar

    PubMed Central

    Gimmestad, Gary; Forrister, Haviland; Grigas, Tomas; O’Dowd, Colin

    2017-01-01

    The Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) instrument on the polar orbiter Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) is an elastic backscatter lidar that produces a global uniformly-calibrated aerosol data set. Several Calibration/Validation (Cal/Val) studies for CALIOP conducted with ground-based lidars and CALIOP data showed large aerosol profile disagreements, both random and systematic. In an attempt to better understand these problems, we undertook a series of ground-based lidar measurements in Atlanta, Georgia, which did not provide better agreement with CALIOP data than the earlier efforts, but rather prompted us to investigate the statistical limitations of such comparisons. Meaningful Cal/Val requires intercomparison data sets with small enough uncertainties to provide a check on the maximum expected calibration error. For CALIOP total attenuated backscatter, reducing the noise to the required level requires averaging profiles along the ground track for distances of at least 1,500 km. Representative comparison profiles often cannot be acquired with ground-based lidars because spatial aerosol inhomogeneities introduce systematic error into the averages. These conclusions have implications for future satellite lidar Cal/Val efforts, because planned satellite lidars measuring aerosol backscatter, wind vector, and CO2 concentration profiles may all produce data requiring considerable along-track averaging for meaningful Cal/Val. PMID:28198389

  8. Intercomparison of Remote and Flight Level Measured Aerosol Backscatter Coefficient During GLOBE 2 Pacific Survey Mission

    NASA Technical Reports Server (NTRS)

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

    1998-01-01

    Aerosol backscatter coefficient data are examined from two local flights undertaken during NASA's GLObal Backscatter Experiment (GLOBE) in May - June, 1990. During each of these two flights the aircraft traversed different altitudes within a region of the atmosphere defined by the same set of latitude and longitude coordinates. This provides an ideal opportunity to allow flight level measured or modeled aerosol backscafter to be compared with pulsed lidar aerosol backscafter data that were obtained at these same altitudes either earlier or later than the flight level measurements. Aerosol backscafter comparisons were made at 1.06-, 9.11- and 9.25-mm wavelengths, using data from three lidar systems and two aerosol optical counters. The best agreement between all sensor's was found in the altitude region below 7 km where backscafter values were moderately high at all three wavelengths. Above this altitude the pulsed lidar backscafter data at 1.06- and 9.25-mm wavelengths were higher than the flight level data obtained from the CW lidar or derived from the optical counters. Possible reasons are offered to explain this discrepancy. During the Japan local flight, microphysics analysis revealed: (1) evidence of a strong advected seasalt aerosol plume from the marine boundary layer, and (2) where backscatter was low, the large lidar sampling volume included many large particles which were of different chemical composition to the small particle category sampled by the particle counters.

  9. Airborne Cavity Ring-Down Measurement of Aerosol Extinction and Scattering During the Aerosol IOP

    NASA Technical Reports Server (NTRS)

    Strawa, A. W.; Ricci, K.; Provencal, R.; Schmid, B.; Covert, D.; Elleman, R.; Arnott, P.

    2003-01-01

    Large uncertainties in the effects of aerosols on climate require improved in-situ measurements of extinction coefficient and single-scattering albedo. This paper describes preliminary results from Cadenza, a new continuous wave cavity ring-down (CW-CRD) instrument designed to address these uncertainties. Cadenza measures the aerosol extinction coefficient for 675 nm and 1550 nm light, and simultaneously measures the scattering coefficient at 675 nm. In the past year Cadenza was deployed in the Asian Dust Above Monterey (ADAM) and DOE Aerosol Intensive Operating Period (IOP) field projects. During these flights Cadenza produced measurements of aerosol extinction in the range from 0.2 to 300 Mm-1 with an estimated precision of 0.1 Min-1 for 1550 nm light and 0.2 Mm-1 for 675 nm light. Cadenza data from the ADAM and Aerosol IOP missions compared favorably with data from the other instruments aboard the CIRPAS Twin Otter aircraft and participating in those projects.= We present comparisons between the Cadenza measurements and those friom a TSI nephelometer, Particle Soot Absorption Photometer (PSAP), and the AATS 14 sun-photometer. Measurements of the optical properties of smoke and dust plumes sampled during these campaigns are presented and estimates of heating rates due to these plumes are made.

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

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

    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).

  11. A comparative study of aerosol extinction measurements made by the SAM II and SAGE satellite experiments

    NASA Technical Reports Server (NTRS)

    Yue, G. K.; Mccormick, M. P.; Chu, W. P.

    1984-01-01

    SAM II and SAGE are two satellite experiments designed to measure stratospheric aerosol extinction using the technique of solar occultation or limb extinction. Although each sensor is mounted aboard a different satellite, there are occasions when their measurement locations are nearly coincident, thereby providing opportunities for a measurement comparison. In this paper, the aerosol extinction profiles and daily contour plots for some of these events in 1979 are reported. The comparisons shown in this paper demonstrate that SAM II and SAGE are producing similar aerosol extinction profiles within their measurement errors and that since SAM II has been previously validated, these results show the validity of the SAGE aerosol measurements.

  12. Comparative studies of aerosol extinction measurements made by the SAM II and SAGE II satellite experiments

    NASA Technical Reports Server (NTRS)

    Yue, Glenn K.; Mccormick, M. P.; Chu, W. P.; Wang, P.; Osborn, M. T.

    1989-01-01

    Results from the Stratospheric Aerosol Measurement (SAM) II and Stratospheric Aerosol and Gas Experiment (SAGE) II are compared for measurement locations which are coincident in time and space. At 1.0 micron, the SAM II and SAGE II aerosol extinction profiles are similar within their measurement errors. In addition, sunrise and sunset aerosol extinction data at four different wavelengths are compared for occasions when the SAGE II and SAM II measurements are nearly coincident in space and about 12 hours apart.

  13. How well can we Measure the Vertical Profile of Tropospheric Aerosol Extinction?

    NASA Technical Reports Server (NTRS)

    Schmid, Beat; Ferrare, R.; Flynn, C.; Elleman, R.; Covert, D.; Strawa, A.; Welton, E.; Turner, D.; Jonsson, H.; Redemann, J.

    2005-01-01

    The recent Department of Energy Atmospheric Radiation Measurement (ARM) Aerosol Intensive Operations Period (MOP, May 2003) yielded one of the best measurement sets obtained to-date to assess our ability to measure the vertical profile of ambient aerosol extinction sigma(sub ep)(lambda) in the lower troposphere. During one month, a heavily instrumented aircraft with well characterized aerosol sampling ability carrying well proven and new aerosol instrumentation, devoted most of the 60 available flight hours to flying vertical profiles over the heavily instrumented ARM Southern Great Plains (SGP) Climate Research Facility (CRF). This allowed us to compare vertical extinction profiles obtained from 6 different instuments: airborne Sun photometer (AATS-14), airborne nephelometer/absorption photometer, airborne cavity ring-down system, ground-based Raman lidar and 2 ground-based elastic backscatter lidars. We find the in-situ measured sigma(sub ep)(lambda) to be lower than the AATS-14 derived values. Bias differences are 0.002 - 0.004 K/m equivalent to 12-17% in the visible, or 45% in the near-infrared. On the other hand, we find that with respect to AATS-14, the lidar sigma(sub ep)(lambda) are higher. An unnoticed loss of sensitivity of the Raman lidar had occurred leading up to AIOP and we expect better agreement from the recently restored system looking at the collective results from 6 field campaigns conducted since 1996, airborne in situ measurements of sigma(sub ep)(lambda) tend to be biased slightly low (17% at visible wavelengths) when compared to airborne Sun photometer sigma(sub ep)(lambda). On the other hand, sigma(sub ep)(lambda) values derived from lidars tend to have no or positive biases. From the bias differences we conclude that the typical systematic error associated with measuring the tropospheric vertical profile of the ambient aerosol extinction with current state of-the art instrumentation is 15-20% at visible wavelengths and potentially larger in

  14. Lidar Ratios for Dust Aerosols Derived From Retrievals of CALIPSO Visible Extinction Profiles Constrained by Optical Depths from MODIS-Aqua and CALIPSO/CloudSat Ocean Surface Reflectance Measurements

    NASA Technical Reports Server (NTRS)

    Young, Stuart A.; Josset, Damien B.; Vaughan, Mark A.

    2010-01-01

    CALIPSO's (Cloud Aerosol Lidar Infrared Pathfinder Satellite Observations) analysis algorithms generally require the use of tabulated values of the lidar ratio in order to retrieve aerosol extinction and optical depth from measured profiles of attenuated backscatter. However, for any given time or location, the lidar ratio for a given aerosol type can differ from the tabulated value. To gain some insight as to the extent of the variability, we here calculate the lidar ratio for dust aerosols using aerosol optical depth constraints from two sources. Daytime measurements are constrained using Level 2, Collection 5, 550-nm aerosol optical depth measurements made over the ocean by the MODIS (Moderate Resolution Imaging Spectroradiometer) on board the Aqua satellite, which flies in formation with CALIPSO. We also retrieve lidar ratios from night-time profiles constrained by aerosol column optical depths obtained by analysis of CALIPSO and CloudSat backscatter signals from the ocean surface.

  15. Two-Column Aerosol Project: Aerosol Light Extinction Measurements Field Campaign Report

    SciTech Connect

    Dubey, Manvendra; Aiken, Allison; Berg, Larry K.; Freedman, Andrew; Gorkowski, Kyle

    2016-09-01

    We deployed Aerodyne Research Inc.’s first Cavity Attenuated Phase Shift extinction (CAPS PMex) monitor (built by Aerodyne) that measures light extinction by using a visible-light-emitting diode (LED) as a light source, a sample cell incorporating two high-reflectivity mirrors centered at the wavelength of the LED, and a vacuum photodiode detector in Cape Cod in 2012/13 for the U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Climate Research Facility’s Two-Column Aerosol Project (TCAP). The efficacy of this instrument is based on the fact that aerosols are broadband scatterers and absorbers of light. The input LED is square-wave modulated and passed through the sample cell that distorts it due to exponential decay by aerosol light absorption and scattering; this is measured at the detector. The amount of phase shift of the light at the detector is used to determine the light extinction. This extinction measurement provides an absolute value, requiring no calibration. The goal was to compare the CAPS performance with direct measurements of absorption with ARM’s baseline photoacoustic soot spectrometer (PASS-3) and nephelometer instruments to evaluate its performance.

  16. Ozone and Aerosol Retrieval from Backscattered Ultraviolet Radiation

    NASA Technical Reports Server (NTRS)

    Bhartia, Pawan K.

    2012-01-01

    In this presentation we will discuss the techniques to estimate total column ozone and aerosol absorption optical depth from the measurements of back scattered ultraviolet (buv) radiation. The total ozone algorithm has been used to create a unique record of the ozone layer, spanning more than 3 decades, from a series of instruments (BUV, SBUV, TOMS, SBUV/2) flown on NASA, NOAA, Japanese and Russian satellites. We will discuss how this algorithm can be considered a generalization of the well-known Dobson/Brewer technique that has been used to process data from ground-based instruments for many decades, and how it differs from the DOAS techniques that have been used to estimate vertical column densities of a host of trace gases from data collected by GOME and SCIAMACHY instruments. The buv aerosol algorithm is most suitable for the detection of UV absorbing aerosols (smoke, desert dust, volcanic ash) and is the only technique that can detect aerosols embedded in clouds. This algorithm has been used to create a quarter century record of aerosol absorption optical depth using the buv data collected by a series of TOMS instruments. We will also discuss how the data from the OMI instrument launched on July 15, 2004 will be combined with data from MODIS and CALIPSO lidar data to enhance the accuracy and information content of satellite-derived aerosol measurements. The OMI and MODIS instruments are currently flying on EOS Aura and EOS Aqua satellites respectively, part of a constellation of satellites called the "A-train".

  17. Retrieval of UV Aerosol Index using backscattered monochromatic radiance measured by GOSAT CAI

    NASA Astrophysics Data System (ADS)

    Go, S.; Kim, J.; KIM, M.; Park, S. S.

    2014-12-01

    UV Aerosol Index(AI) using backscattered radiance at a single channel has been retrieved. In the current UV AI algorithm, two UV channels are used to contrast the absorbing aerosol loaded atmosphere to Rayleigh scattering condition. There have been needs to retrieve information of absorbing aerosol from a single UV channel, such as GOSAT CAI. 30-day minimum composite method, however, makes the process possible to construct the condition with the use of only single UV channel. Also, absorption by aerosol changes with respect to AOD and wavelength for different aerosol types. Therefore, single channel aerosol index(SAI) can detect absorbing aerosol qualitatively. Correlation coefficient of SAI to current UV AI indicate significant value, showing possibility of detecting highly absorbing aerosols. The application of a cloud screening makes the presence of absorbing aerosols even more clear. Radiative transfer calculations using VLIDORT were performed to test the sensitivity of SAI and UV AI to aerosol optical properties, showing that highly absorbing aerosol results in meaningful SAI. Results from dust case study in East Asia show reasonable performance of SAI for the region with single scattering albedo below 0.90. This study concludes with a comparison of SAI from GOSAT lv.1b data to OMI UVAI data, where reasonable agreement and low false detection was found for dust cases in East Asia. The SAI value of -0.2 to 0.0 from GOSAT-CAI was comparable to OMI dust threshold value of 0.7. These findings corroborate the suitability of SAI as a for detecting absorbing aerosols for satellite instrument with a single UV channel.

  18. A tunable coherent CO2 lidar for measurements of atmospheric aerosol backscatter and attenuation

    NASA Technical Reports Server (NTRS)

    Menzies, R. T.

    1983-01-01

    A coherent laser radar system using a grating-tunable, injection-locked TEA-CO2 transmitter is being used to measure the altitude dependence of atmospheric aerosol backscatter and attenuation at a variety of CO2 laser wavelengths in the 9-11 micron region. Injection control of the TEA-CO2 laser allows one to obtain Single-Longitudinal-Mode (SLM) pulses which will follow the frequency of the injected radiation if the TEA laser cavity length is adjusted so that a cavity resonance is in proximity with the injected signal frequency, and if various additional conditions are satisfied. Requirements for generation of SLM pulses in this manner from a TEA CO2 laser with an unstable resonator cavity will be discussed. Procedures used for quantitative range-gated measurements of aerosol backscatter and attenuation will also be discussed.

  19. Backscatter laser depolarization studies of simulated stratospheric aerosols: Crystallized sulfuric acid droplets

    NASA Technical Reports Server (NTRS)

    Sassen, Kenneth; Zhao, Hongjie; Yu, Bing-Kun

    1988-01-01

    The optical depolarizing properties of simulated stratospheric aerosols were studied in laboratory laser (0.633 micrometer) backscattering experiments for application to polarization lidar observations. Clouds composed of sulfuric acid solution droplets, some treated with ammonia gas, were observed during evaporation. The results indicate that the formation of minute ammonium sulfate particles from the evaporation of acid droplets produces linear depolarization ratios of beta equivalent to 0.02, but beta equivalent to 0.10 to 0.15 are generated from aged acid cloud aerosols and acid droplet crystallization effects following the introduction of ammonia gas into the chamber. It is concluded that partially crystallized sulfuric acid droplets are a likely candidate for explaining the lidar beta equivalent to 0.10 values that have been observed in the lower stratosphere in the absence of the relatively strong backscattering from homogeneous sulfuric acid droplet (beta equivalent to 0) or ice crystal (beta equivalent to 0.5) clouds.

  20. Backscatter laser depolarization studies of simulated stratospheric aerosols - Crystallized sulfuric acid droplets

    NASA Technical Reports Server (NTRS)

    Sassen, Kenneth; Zhao, Hongjie; Yu, Bing-Kun

    1989-01-01

    The optical depolarizing properties of simulated stratospheric aerosols were studied in laboratory laser (0.633 micrometer) backscattering experiments for application to polarization lidar observations. Clouds composed of sulfuric acid solution droplets, some treated with ammonia gas, were observed during evaporation. The results indicate that the formation of minute ammonium sulfate particles from the evaporation of acid droplets produces linear depolarization ratios of beta equivalent to 0.02, but beta equivalent to 0.10 to 0.15 are generated from aged acid cloud aerosols and acid droplet crystalization effects following the introduction of ammonia gas into the chamber. It is concluded that partially crystallized sulfuric acid droplets are a likely candidate for explaining the lidar beta equivalent to 0.10 values that have been observed in the lower stratosphere in the absence of the relatively strong backscattering from homogeneous sulfuric acid droplet (beta equivalent to 0) or ice crystal (beta equivalent to 0.5) clouds.

  1. Simultaneous measurements of particle backscattering and extinction coefficients and wind velocity by lidar with a Mach-Zehnder interferometer: principle of operation and performance assessment

    NASA Astrophysics Data System (ADS)

    Bruneau, Didier; Pelon, Jacques

    2003-02-01

    The development of remote-sensing instruments that can be used to monitor several parameters at the same time is important for the study of complex processes such as those that control climate and environment. In this paper the performance of a new concept of lidar receiver that allows for the direct measurement of aerosol and cloud optical properties simultaneously with wind velocity is investigated. This receiver uses a Mach-Zehnder interferometer. Two different configurations, either with four photometric output channels or with fringe imaging on a multichannel detector, are studied. Analytical expressions of the statistical errors are given under the assumption of Gaussian signal spectra. It is shown that similar accuracies can be achieved for both configurations. Performance modeling of the retrieval of semitransparent cloud optical scattering properties and wind velocity was done at different operation wavelengths for a Nd:YAG laser source. Results for such a lidar system onboard an aircraft flying at an altitude of 12 km show that for semitransparent clouds the best results were obtained at 355 nm, with relative standard deviations of 0.5% and 5% for the backscatter and extinction coefficients, respectively, together with a velocity accuracy of 0.2 ms-1. The accuracy of optical properties retrieved for boundary layer aerosols are comparable, whereas the velocity accuracy is decreased to 1 ms-1. Finally, an extrapolation to a large 355-nm spaceborne lidar shows accuracies in the range from 2.5% to 5% for the backscatter coefficient and from 10% to 15% for the extinction coefficient together with a vertical wind speed accuracy of better than 0.5 ms-1 for semitransparent clouds and boundary layer, with a vertical resolution of 500 m and a 100 shot averaging.

  2. Extinction spectra of mineral dust aerosol components in an environmental aerosol chamber: IR resonance studies

    NASA Astrophysics Data System (ADS)

    Mogili, Praveen K.; Yang, K. H.; Young, Mark A.; Kleiber, Paul D.; Grassian, Vicki H.

    Mineral dust aerosol plays an important role in determining the physical and chemical equilibrium of the atmosphere. To better understand the impact that mineral dust aerosol may have on climate forcing and on remote sensing, we have initiated a study of the optical properties of important components of mineral dust aerosol including silicate clays (illite, kaolinite, and montmorillonite), quartz, anhydrite, and calcite. The extinction spectra are measured in an environmental simulation chamber over a broad wavelength range, which includes both the IR (650-5000 cm -1) and UV-vis (12,500-40,000 cm -1) spectral regions. In this paper, we focus on the IR region from 800 to 1500 cm -1, where many of these mineral dust constituents have characteristic vibrational resonance features. Experimental spectra are compared with Mie theory simulations based on published mineral optical constants. We find that Mie theory generally does a poor job in fitting the IR resonance peak positions and band profiles for nonspherical aerosols in the accumulation mode size range ( D˜0.1-2.5 μm). We explore particle shape effects on the IR resonance line profiles by considering analytic models for extinction of particles with characteristic shapes (i.e. disks, needles, and ellipsoids). Interestingly, Mie theory often appears to give more accurate results for the absorption line profiles of larger particles that fall in the coarse mode size range.

  3. Direct evaluation of aerosol-mass loadings from multispectral extinction data

    NASA Technical Reports Server (NTRS)

    Box, M. A.; Mckellar, B. H. J.

    1978-01-01

    A formula is derived for the evaluation of the total volume of aerosol in a column, and hence for the aerosol columnar mass loading, from multispectral extinction data. This formula is exact in the 'anomalous diffraction' approximation, and reasonably accurate for Mie scattering, over a fairly wide range of refractive indices typical of real aerosols.

  4. Vertical Profiling of Atmospheric Backscatter with a Raman-Aerosol Lidar

    NASA Astrophysics Data System (ADS)

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

    2010-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2010-04-01

    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 μm 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.

  6. Optical modeling of aerosol extinction for remote sensing in the marine environment

    NASA Astrophysics Data System (ADS)

    Kaloshin, G. A.

    2013-05-01

    A microphysical model is presented for the surface layer marine and coastal atmospheric aerosols that is based on long-term observations of size distributions for 0.01-100 μm particles in different geographic sites. The fundamental feature of the model is a parameterization of amplitudes and widths for aerosol modes of the aerosol size distribution function (ASDF) as functions of fetch and wind speed. The shape of the ASDF and its dependence on meteorological parameters, altitudes above sea level (H), fetch (X), wind speed (U) and relative humidity (RH) are investigated. The spectral profiles of the aerosol extinction coefficients calculated by MaexPro (Marine Aerosol Extinction Profiles) are in good agreement with observational data and the numerical results obtained from the Navy Aerosol Model (NAM) and the Advanced Navy Aerosol Model (ANAM). Moreover, MaexPro was found to be an accurate and reliable tool for investigation of the optical properties of atmospheric aerosols.

  7. Toward a Combined SAGE II-HALOE Aerosol Climatology: An Evaluation of HALOE Version 19 Stratospheric Aerosol Extinction Coefficient Observations

    NASA Technical Reports Server (NTRS)

    Thomason, L. W.

    2012-01-01

    Herein, the Halogen Occultation Experiment (HALOE) aerosol extinction coefficient data is evaluated in the low aerosol loading period after 1996 as the first necessary step in a process that will eventually allow the production of a combined HALOE/SAGE II (Stratospheric Aerosol and Gas Experiment) aerosol climatology of derived aerosol products including surface area density. Based on these analyses, it is demonstrated that HALOE's 3.46 microns is of good quality above 19 km and suitable for scientific applications above that altitude. However, it is increasingly suspect at lower altitudes and should not be used below 17 km under any circumstances after 1996. The 3.40 microns is biased by about 10% throughout the lower stratosphere due to the failure to clear NO2 but otherwise appears to be a high quality product down to 15 km. The 2.45 and 5.26 micron aerosol extinction coefficient measurements are clearly biased and should not be used for scientific applications after the most intense parts of the Pinatubo period. Many of the issues in the aerosol data appear to be related to either the failure to clear some interfering gas species or doing so poorly. For instance, it is clear that the 3.40micronaerosol extinction coefficient measurements can be improved through the inclusion of an NO2 correction and could, in fact, end up as the highest quality overall HALOE aerosol extinction coefficient measurement. It also appears that the 2.45 and 5.26 micron channels may be improved by updating the Upper Atmosphere Pilot Database which is used as a resource for the removal of gas species otherwise not available from direct HALOE measurements. Finally, a simple model to demonstrate the promise of mixed visible/infrared aerosol extinction coefficient ensembles for the retrieval of bulk aerosol properties demonstrates that a combined HALOE/SAGE II aerosol climatology is feasible and may represent a substantial improvement over independently derived data sets.

  8. Vertical distribution of near-ground aerosol backscattering coefficient measured by a CCD side-scattering lidar

    NASA Astrophysics Data System (ADS)

    Tao, Zongming; Liu, Dong; Ma, Xiaomin; Shi, Bo; Shan, Huihui; Zhao, Ming; Xie, Chenbo; Wang, Yingjian

    2015-09-01

    The near-ground aerosols have the most impact on the human beings. Its fine spatial and temporal distribution, with which the environmental and meteorological departments concern themselves most, has not been elaborated very well due to the unavailable measurement tools. We present the continuous observations of the vertical profile of near-ground aerosol backscattering coefficients by employing our self-developed side-scattering lidar system based on charge-coupled device camera. During the experimental period from April 2013 to August 2014, four catalogs of aerosol backscattering coefficient profiles are found in the near ground. The continuous measurement is revealed by the contour plots measured during the whole night. These experimental results indicate that the aerosol backscattering coefficients in near ground are inhomogeneous and vary with altitude and time, which are very useful for the model researchers to study the regional air pollution and its climate impact.

  9. Use of In Situ Cloud Condensation Nuclei, Extinction, and Aerosol Size Distribution Measurements to Test a Method for Retrieving Cloud Condensation Nuclei Profiles From Surface Measurements

    NASA Technical Reports Server (NTRS)

    Ghan, Stephen J.; Rissman, Tracey A.; Ellman, Robert; Ferrare, Richard A.; Turner, David; Flynn, Connor; Wang, Jian; Ogren, John; Hudson, James; Jonsson, Haflidi H.; VanReken, Timothy; Flagan, Richard C.; Seinfeld, John H.

    2006-01-01

    If the aerosol composition and size distribution below cloud are uniform, the vertical profile of cloud condensation nuclei (CCN) concentration can be retrieved entirely from surface measurements of CCN concentration and particle humidification function and surface-based retrievals of relative humidity and aerosol extinction or backscatter. This provides the potential for long-term measurements of CCN concentrations near cloud base. We have used a combination of aircraft, surface in situ, and surface remote sensing measurements to test various aspects of the retrieval scheme. Our analysis leads us to the following conclusions. The retrieval works better for supersaturations of 0.1% than for 1% because CCN concentrations at 0.1% are controlled by the same particles that control extinction and backscatter. If in situ measurements of extinction are used, the retrieval explains a majority of the CCN variance at high supersaturation for at least two and perhaps five of the eight flights examined. The retrieval of the vertical profile of the humidification factor is not the major limitation of the CCN retrieval scheme. Vertical structure in the aerosol size distribution and composition is the dominant source of error in the CCN retrieval, but this vertical structure is difficult to measure from remote sensing at visible wavelengths.

  10. How Well do State-of-the-Art Techniques Measuring the Vertical Profile of Tropospheric Aerosol Extinction Compare?

    NASA Technical Reports Server (NTRS)

    Schmid, B.; Ferrare, R.; Flynn, C.; Elleman, R.; Covert, D.; Strawa, A.; Welton, E.; Turner, D.; Jonsson, H.; Redemann, J.; Eilers, J.; Ricci, K.; Hallar, A. G.; Clayton, M.; Michalsky, J.; Smirnov, A.; Holben, B.; Barnard, J.

    2006-01-01

    The recent Department of Energy Atmospheric Radiation Measurement (ARM) Aerosol Intensive Operations Period (AIOP, May 2003) yielded one of the best measurement sets obtained to date to assess our ability to measure the vertical profile of ambient aerosol extinction sigma(ep)(lambda) in the lower troposphere. During one month, a heavily instrumented aircraft with well-characterized aerosol sampling ability carrying well-proven and new aerosol instrumentation devoted most of the 60 available flight hours to flying vertical profiles over the heavily instrumented ARM Southern Great Plains (SGP) Climate Research Facility (CRF). This allowed us to compare vertical extinction profiles obtained from six different instruments: airborne Sun photometer (AATS-14), airborne nephelometer/absorption photometer, airborne cavity ring-down system, groundbased Raman lidar, and two ground-based elastic backscatter lidars. We find the in situ measured sigma(ep)(lambda) to be lower than the AATS-14 derived values. Bias differences are 0.002-0.004 Km!1 equivalent to 13-17% in the visible, or 45% in the near-infrared. On the other hand, we find that with respect to AATS-14, the lidar sigma(ep)(lambda) are higher: Bias differences are 0.004 Km(-1) (13%) and 0.007 Km(-1) (24%) for the two elastic backscatter lidars (MPLNET and MPLARM, lambda = 523 nm) and 0.029 Km(-1) (54%) for the Raman lidar (lambda = 355 nm). An unnoticed loss of sensitivity of the Raman lidar had occurred leading up to AIOP, and we expect better agreement from the recently restored system. Looking at the collective results from six field campaigns conducted since 1996, airborne in situ measurements of sigma(ep)(lambda) tend to be biased slightly low (17% at visible wavelengths) when compared to airborne Sun photometer sigma(ep)(lambda). On the other hand, sigma(ep)(lambda) values derived from lidars tend to have no or positive biases. From the bias differences we conclude that the typical systematic error associated

  11. Accuracy of near-surface aerosol extinction determined from columnar aerosol optical depth measurements in Reno, NV, USA

    NASA Astrophysics Data System (ADS)

    Loría-Salazar, S. Marcela; Arnott, W. Patrick; Moosmüller, Hans

    2014-10-01

    The aim of the present work is a detailed analysis of aerosol columnar optical depth as a tool to determine near-surface aerosol extinction in Reno, Nevada, USA, during the summer of 2012. Ground and columnar aerosol optical properties were obtained by use of in situ Photoacoustic and Integrated Nephelometer and Cimel CE-318 Sun photometer instruments, respectively. Both techniques showed that seasonal weather changes and fire plumes had enormous influence on local aerosol optics. The apparent optical height followed the shape but not magnitude of the development of the convective boundary layer when fire conditions were not present. Back trajectory analysis demonstrated that a local flow known as the Washoe Zephyr circulation often induced aerosol transport from Northern California over the Sierra Nevada Mountains that increased the aerosol optical depth at 500 nm during afternoons when compared with mornings. Aerosol fine mode fraction indicated that afternoon aerosols in June and July and fire plumes in August were dominated by submicron particles, suggesting upwind urban plume biogenically enhanced evolution toward substantial secondary aerosol formation. This fine particle optical depth was inferred to be beyond the surface, thereby complicating use of remote sensing measurements for near-ground aerosol extinction measurements. It is likely that coarse mode depletes fine mode aerosol near the surface by coagulation and condensation of precursor gases.

  12. Theory of CW lidar aerosol backscatter measurements and development of a 2.1 microns solid-state pulsed laser radar for aerosol backscatter profiling

    NASA Technical Reports Server (NTRS)

    Kavaya, Michael J.; Henderson, Sammy W.; Frehlich, R. G.

    1991-01-01

    The performance and calibration of a focused, continuous wave, coherent detection CO2 lidar operated for the measurement of atmospheric backscatter coefficient, B(m), was examined. This instrument functions by transmitting infrared (10 micron) light into the atmosphere and collecting the light which is scattered in the rearward direction. Two distinct modes of operation were considered. In volume mode, the scattered light energy from many aerosols is detected simultaneously, whereas in the single particle mode (SPM), the scattered light energy from a single aerosol is detected. The analysis considered possible sources of error for each of these two cases, and also considered the conditions where each technique would have superior performance. The analysis showed that, within reasonable assumptions, the value of B(m) could be accurately measured by either the VM or the SPM method. The understanding of the theory developed during the analysis was also applied to a pulsed CO2 lidar. Preliminary results of field testing of a solid state 2 micron lidar using a CW oscillator is included.

  13. Spectrally-resolved measurements of aerosol extinction at ultraviolet and visible wavelengths

    NASA Astrophysics Data System (ADS)

    Flores, M.; Washenfelder, R. A.; Brock, C. A.; Brown, S. S.; Rudich, Y.

    2012-12-01

    Aerosols play an important role in the Earth's radiative budget. Aerosol extinction includes both the scattering and absorption of light, and these vary with wavelength, aerosol diameter, and aerosol composition. Historically, aerosol absorption has been measured using filter-based or extraction methods that are prone to artifacts. There have been few investigations of ambient aerosol optical properties at the blue end of the visible spectrum and into the ultraviolet. Brown carbon is particularly important in this spectral region, because it both absorbs and scatters light, and encompasses a large and variable group of organic compounds from biomass burning and secondary organic aerosol. We have developed a laboratory instrument that combines new, high-power LED light sources with high-finesse optical cavities to achieve sensitive measurements of aerosol optical extinction. This instrument contains two broadband channels, with spectral coverage from 360 - 390 nm and 385 - 420 nm. Using this instrument, we report aerosol extinction in the ultraviolet and near-visible spectral region as a function of chemical composition and structure. We have measured the extinction cross-sections between 360 - 420 nm with 0.5 nm resolution using different sizes and concentrations of polystyrene latex spheres, ammonium sulfate, and Suwannee River fulvic acid. Fitting the real and imaginary part of the refractive index allows the absorption and scattering to be determined.

  14. Mid-infrared extinction by sulfate aerosols from the Mt. Pinatubo eruption

    NASA Technical Reports Server (NTRS)

    Rinsland, C. P.; Yue, G. K.; Gunson, M. R.; Zander, R.; Abrams, M. C.

    1994-01-01

    Quantitative measurements of the wavelength dependence of aerosol extinction in the 750-3400/cm spectral region have been derived from 0.01/cm resolution stratospheric solar occultation spectra recorded by the ATMOS (Atmospheric Trace Molecule Spectroscopy) Fourier transform spectrometer about 9 1/2 months after the Mt Pinatubo volcanic eruption. Strong, broad aerosol features have been identified near 900, 1060, 1190, 1720, and 2900/cm below a tangent height of approximately 30 km. Aerosol extinction measurements derived from approximately 0.05/cm wide microwindows nearly free of telluric line absorption in the ATMOS spectra are compared with transmission calculations derived from aerosol size distribution profiles retrieved from correlative SAGE (Stratospheric Aerosol and Gas Experiment) II visible and near i.r. extinction measurements, seasonal and zonally averaged H2SO4 aerosol weight percentage profiles, and published sulfuric acid optical constants derived from room temperature laboratory measurements. The calculated shapes and positions of the aerosol features are generally consistent with the observations, thereby confirming that the aerosols are predominantly concentrated H2SO4-H2O droplets, but there are significant differences between the measured and calculated wavelength dependences of the aerosol extinction. We attribute these differences as primarily the result of errors in the calculated low temperature H2SO4-H2O optical constants. Errors in both the published room temperature optical constants and the limitations of the Lorentz-Lorenz relation are likely to be important.

  15. Light extinction by Secondary Organic Aerosol: an intercomparison of three broadband cavity spectrometers

    NASA Astrophysics Data System (ADS)

    Varma, R. M.; Ball, S. M.; Brauers, T.; Dorn, H.-P.; Heitmann, U.; Jones, R. L.; Platt, U.; Pöhler, D.; Ruth, A. A.; Shillings, A. J. L.; Thieser, J.; Wahner, A.; Venables, D. S.

    2013-07-01

    Broadband optical cavity spectrometers are maturing as a technology for trace gas detection, but only recently have they been used to retrieve the extinction coefficient of aerosols. Sensitive broadband extinction measurements allow explicit separation of gas and particle phase spectral contributions, as well as continuous spectral measurements of aerosol extinction in favourable cases. In this work, we report an intercomparison study of the aerosol extinction coefficients measured by three such instruments: a broadband cavity ring-down spectrometer (BBCRDS), a cavity-enhanced differential optical absorption spectrometer (CE-DOAS), and an incoherent broadband cavity-enhanced absorption spectrometer (IBBCEAS). Experiments were carried out in the SAPHIR atmospheric simulation chamber as part of the NO3Comp campaign to compare the measurement capabilities of NO3 and N2O5 instrumentation. Aerosol extinction coefficients between 655 and 690 nm are reported for secondary organic aerosols (SOA) formed by the NO3 oxidation of β-pinene under dry and humid conditions. Despite different measurement approaches and spectral analysis procedures, the three instruments retrieved aerosol extinction coefficients that were in close agreement. The refractive index of SOA formed from the β-pinene + NO3 reaction was 1.61, and was not measurably affected by the chamber humidity or by aging of the aerosol over several hours. This refractive index is significantly larger than SOA refractive indices observed in other studies of OH and ozone-initiated terpene oxidations, and may be caused by the large proportion of organic nitrates in the particle phase. In an experiment involving ammonium sulphate particles the aerosol extinction coefficients as measured by IBBCEAS were found to be in reasonable agreement with those calculated using Mie theory. The results of the study demonstrate the potential of broadband cavity spectrometers for determining the optical properties of aerosols.

  16. Light extinction by secondary organic aerosol: an intercomparison of three broadband cavity spectrometers

    NASA Astrophysics Data System (ADS)

    Varma, R. M.; Ball, S. M.; Brauers, T.; Dorn, H.-P.; Heitmann, U.; Jones, R. L.; Platt, U.; Pöhler, D.; Ruth, A. A.; Shillings, A. J. L.; Thieser, J.; Wahner, A.; Venables, D. S.

    2013-11-01

    Broadband optical cavity spectrometers are maturing as a technology for trace-gas detection, but only recently have they been used to retrieve the extinction coefficient of aerosols. Sensitive broadband extinction measurements allow explicit separation of gas and particle phase spectral contributions, as well as continuous spectral measurements of aerosol extinction in favourable cases. In this work, we report an intercomparison study of the aerosol extinction coefficients measured by three such instruments: a broadband cavity ring-down spectrometer (BBCRDS), a cavity-enhanced differential optical absorption spectrometer (CE-DOAS), and an incoherent broadband cavity-enhanced absorption spectrometer (IBBCEAS). Experiments were carried out in the SAPHIR atmospheric simulation chamber as part of the NO3Comp campaign to compare the measurement capabilities of NO3 and N2O5 instrumentation. Aerosol extinction coefficients between 655 and 690 nm are reported for secondary organic aerosols (SOA) formed by the NO3 oxidation of β-pinene under dry and humid conditions. Despite different measurement approaches and spectral analysis procedures, the three instruments retrieved aerosol extinction coefficients that were in close agreement. The refractive index of SOA formed from the β-pinene + NO3 reaction was 1.61, and was not measurably affected by the chamber humidity or by aging of the aerosol over several hours. This refractive index is significantly larger than SOA refractive indices observed in other studies of OH and ozone-initiated terpene oxidations, and may be caused by the large proportion of organic nitrates in the particle phase. In an experiment involving ammonium sulfate particles, the aerosol extinction coefficients as measured by IBBCEAS were found to be in reasonable agreement with those calculated using the Mie theory. The results of the study demonstrate the potential of broadband cavity spectrometers for determining the optical properties of aerosols.

  17. Spectral Aerosol Extinction (SpEx): a new instrument for in situ ambient aerosol extinction measurements across the UV/visible wavelength range

    NASA Astrophysics Data System (ADS)

    Jordan, C. E.; Anderson, B. E.; Beyersdorf, A. J.; Corr, C. A.; Dibb, J. E.; Greenslade, M. E.; Martin, R. F.; Moore, R. H.; Scheuer, E.; Shook, M. A.; Thornhill, K. L.; Troop, D.; Winstead, E. L.; Ziemba, L. D.

    2015-06-01

    We introduce a new instrument for the measurement of in situ ambient aerosol extinction over the 300-700 nm wavelength range, the Spectral Aerosol Extinction (SpEx) instrument. This measurement capability is envisioned to complement existing in situ instrumentation, allowing for simultaneous measurement of the evolution of aerosol optical, chemical, and physical characteristics in the ambient environment. In this work, a detailed description of the instrument is provided along with characterization tests performed in the laboratory. Measured spectra of NO2 and polystyrene latex spheres (PSLs) agreed well with theoretical calculations. Good agreement was also found with simultaneous aerosol extinction measurements at 450, 530, and 630 nm using CAPS PMex instruments in a series of 22 tests including non-absorbing compounds, dusts, soot, and black and brown carbon analogs. SpEx can more accurately distinguish the presence of brown carbon from other absorbing aerosol due to its 300 nm lower wavelength limit compared to measurements limited to visible wavelengths. Extinction spectra obtained with SpEx contain more information than can be conveyed by a simple power law fit (typically represented by Ångström Exponents). Planned future improvements aim to lower detection limits and ruggedize the instrument for mobile operation.

  18. Aerosol size distribution, composition, and CO sub 2 backscatter at Mauna Loa Observatory

    SciTech Connect

    Clarke, A.D.; Porter, J.N. )

    1991-03-20

    Continuous measurements of aerosol size distributions were obtained during Jan-Mar and Nov-Dec periods of 1988 at Mauna Loa Observatory, Hawaii. These periods were chosen in order to characterize aerosol physiochemistry during periods representative of low-dust atmospheric conditions and periods associated with appreciable Asian dust transport to that site. Size distributions for particles with diameters between 0.15 and 7.6 {mu}m were accumulated in 256 size bins of a laser optical particle counter for 3-hour intervals during most of the period. The aerosol sample stream was heated to selected temperatures in order to provide size-discriminated measurements of aerosol volatility. Resulting data were used to assess the variability in aerosol concentrations and properties related to aerosol backscatter values at a wavelength of 10.6 {mu}m, {beta}{sub CO{sub 2}}, in the mid-troposphere. Low aerosol concentrations, considered representative of mid-tropospheric air, occurred in downslope flow between midnight and sunrise. Measurements for these time periods suggest that {beta}{sub CO{sub 2}} varied from a low of about 5 {times} 10{sup {minus}12}m{sup {minus}1}sr{sup {minus}1} to a high of 5 {times} 10{sup {minus}8}m{sup {minus}1}sr{sup {minus}1}. Coarse particles with diameters between 1.0 and 5.0 {mu}m account for most of the derived values of {beta}{sub CO{sub 2}} at all but the highest and lowest aerosol mass concentrations. Volatile aerosol appears to dominate aerosol mass during the cleanest periods but was a small fraction of the total during dust events. The authors estimate that minimum values for {beta}{sub CO{sub 2}} at about 8 km should usually fall in the range of 1-3 {times} 10{sup {minus}12}m{sup {minus}1}sr{sup {minus}1} and be dominated by a sulfate aerosol.

  19. Field Studies of Broadband Aerosol Optical Extinction in the Ultraviolet Spectral Region

    NASA Astrophysics Data System (ADS)

    Washenfelder, R. A.; Attwood, A.; Brock, C. A.; Brown, S. S.

    2013-12-01

    Aerosols influence the Earth's radiative budget by scattering and absorbing incoming solar radiation. The optical properties of aerosols vary as a function of wavelength, but few measurements have reported the wavelength dependence of aerosol extinction cross sections and complex refractive indices. In the case of brown carbon, its wavelength-dependent absorption in the ultraviolet spectral region has been suggested as an important component of aerosol radiative forcing. We describe a new field instrument to measure aerosol optical extinction as a function of wavelength, using cavity enhanced spectroscopy with a broadband light source. The instrument consists of two broadband channels which span the 360-390 and 385-420 nm spectral regions using two light emitting diodes (LED) and a grating spectrometer with charge-coupled device (CCD) detector. We deployed this instrument during the Fire Lab at Missoula Experiment during Fall 2012 to measure biomass burning aerosol, and again during the Southern Oxidant and Aerosol Study in summer 2013 to measure organic aerosol in the Southeastern U.S. In both field experiments, we determined aerosol optical extinction as a function of wavelength and can interpret this together with size distribution and composition measurements to characterize the aerosol optical properties and radiative forcing.

  20. Comparison of LIDAR and Cavity Ring-Down Measurements of Aerosol Extinction and Study of Inferred Aerosol Gradients

    NASA Astrophysics Data System (ADS)

    Eberhard, W. L.; Massoli, P.; McCarty, B. J.; Machol, J. L.; Tucker, S. C.

    2007-12-01

    A LIDAR and a Cavity Ring-Down Aerosol Extinction Spectrometer (CRD) instrument simultaneously measured aerosol extinction at 355-nm wavelength from aboard the Research Vessel Ronald H. Brown during the Texas Air Quality Study II campaign. The CRD measured air sampled from the top of the common mast used by several in situ aerosol optical and chemical instruments. The LIDAR's scan sequence included near-horizontal stares (2° elevation angle) with pointing corrected for ship's roll. Aerosol extinction was retrieved using a variant of the slope method. The LIDAR therefore sampled air over a short vertical extent with midpoint higher above the surface than the CRD intake and at a horizontal distance of as much as a few kilometers. The CRD measured aerosol extinction at dry and at high (near-ambient) relative humidity (RH) levels, which were used to scale the measurements to ambient RH for the comparisons. Data from the two instruments for well-mixed conditions (supported by turbulence and atmospheric stability data) are compared to evaluate the degree of agreement between the two methods and reasons for differences. For instances of larger differences, the aerosol gradient below approximately 100 m altitude is inferred and examined in context of low-level meteorological parameters and LIDAR measurements at higher angles.

  1. Two-wavelength backscattering lidar for stand off detection of aerosols

    NASA Astrophysics Data System (ADS)

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

    2008-10-01

    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 (λ1 = 1064 nm and λ2 = 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.

  2. Seasonal and diurnal variations of aerosol extinction profile and type distribution from CALIPSO 5-year observations

    NASA Astrophysics Data System (ADS)

    Huang, Lei; Jiang, Jonathan H.; Tackett, Jason L.; Su, Hui; Fu, Rong

    2013-05-01

    The new Level 3 aerosol profile data derived from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) provide a multiyear global aerosol distribution with high vertical resolution. We analyzed seasonal and diurnal variations of the vertical distributions of aerosol properties represented by 5-year CALIPSO data. Results show that dust, smoke, and polluted dust are the most frequently detected aerosol types during all seasons. Dust is the dominant type, especially in the middle to upper troposphere, over most areas during boreal spring and summer, while smoke and polluted dust tend to dominate during biomass burning seasons. The seasonal variations of dust layer top height and dust contribution to all-aerosol extinction are positively correlated with the seasonal variation of the dust occurrence frequency. The seasonal cycle of aerosol properties over west Australia is similar to that over biomass burning regime areas, despite its desert regime. In general, smoke is detected more frequently from the lower to middle troposphere; clean marine and polluted continental aerosols are detected more frequently, while polluted dust is detected less frequently, in the lower troposphere during nighttime than daytime. The all-aerosol extinction is generally larger, and the aerosol layer top is detected at high altitudes more frequently during nighttime than daytime. The diurnal changes of aerosol properties are similar within the same aerosol regime. Dust extinction shows little diurnal variation except when dust is the dominant aerosol type. The results contribute to an initial global 3-D aerosol climatology which will likely be extended and improved in the future.

  3. Spectral aerosol extinction (SpEx): a new instrument for in situ ambient aerosol extinction measurements across the UV/visible wavelength range

    NASA Astrophysics Data System (ADS)

    Jordan, C. E.; Anderson, B. E.; Beyersdorf, A. J.; Corr, C. A.; Dibb, J. E.; Greenslade, M. E.; Martin, R. F.; Moore, R. H.; Scheuer, E.; Shook, M. A.; Thornhill, K. L.; Troop, D.; Winstead, E. L.; Ziemba, L. D.

    2015-11-01

    We introduce a new instrument for the measurement of in situ ambient aerosol extinction over the 300-700 nm wavelength range, the spectral aerosol extinction (SpEx) instrument. This measurement capability is envisioned to complement existing in situ instrumentation, allowing for simultaneous measurement of the evolution of aerosol optical, chemical, and physical characteristics in the ambient environment. In this work, a detailed description of the instrument is provided along with characterization tests performed in the laboratory. Measured spectra of NO2 and polystyrene latex spheres (PSLs) agreed well with theoretical calculations. Good agreement was also found with simultaneous aerosol extinction measurements at 450, 530, and 630 nm using CAPS PMex instruments in a series of 22 tests including nonabsorbing compounds, dusts, soot, and black and brown carbon analogs. SpEx measurements are expected to help identify the presence of ambient brown carbon due to its 300 nm lower wavelength limit compared to measurements limited to longer UV and visible wavelengths. Extinction spectra obtained with SpEx contain more information than can be conveyed by a simple power law fit (typically represented by Ångström exponents). Planned future improvements aim to lower detection limits and ruggedize the instrument for mobile operation.

  4. Visible and infrared extinction of atmospheric aerosol in the marine and coastal environment.

    PubMed

    Kaloshin, Gennady A

    2011-05-10

    The microphysical model Marine Aerosol Extinction Profiles (MaexPro) for surface layer marine and coastal atmospheric aerosols, which is based on long-term observations of size distributions for 0.01-100 μm particles, is presented. The fundamental feature of the model is a parameterization of amplitudes and widths for aerosol modes of the aerosol size distribution function (ASDF) as functions of fetch and wind speed. The shape of the ASDF and its dependence on meteorological parameters, altitudes above the sea level (H), fetch (X), wind speed (U), and relative humidity is investigated. The model is primarily to characterize aerosols for the near-surface layer (within 25 m). The model is also applicable to higher altitudes within the atmospheric boundary layer, where the change in the vertical profile of aerosol is not very large. In this case, it is only valid for "clean" marine environments, in the absence of air pollution or any other major sources of continental aerosols, such desert dust or smoke from biomass burning. The spectral profiles of the aerosol extinction coefficients calculated by MaexPro are in good agreement with observational data and the numerical results obtained by the well-known Navy Aerosol Model and Advanced Navy Aerosol Model codes. Moreover, MaexPro was found to be an accurate and reliable instrument for investigation of the optical properties of atmospheric aerosols.

  5. Spectral Aerosol Extinction (SpEx): A New Instrument for In situ Ambient Aerosol Extinction Measurements Across the UV/Visible Wavelength Range

    NASA Technical Reports Server (NTRS)

    Jordan, C. E.; Anderson, B. E.; Beyersdorf, A. J.; Corr, C. A.; Dibb, J. E.; Greenslade, M. E.; Martin, R. F.; Moore, R. H.; Scheuer, E.; Shook, M. A.; Thornhill, K. L.; Troop, D.; Winstead, Edward L.; Ziemba, L. D.

    2015-01-01

    We introduce a new instrument for the measurement of in situ ambient aerosol extinction over the 300-700 nm wavelength range, the Spectral Aerosol Extinction (SpEx) instrument. This measurement capability is envisioned to complement existing in situ instrumentation, allowing for simultaneous measurement of the evolution of aerosol optical, chemical, and physical characteristics in the ambient environment. In this work, a detailed description of the instrument is provided along with characterization tests performed in the laboratory. Measured spectra of NO2 and polystyrene latex spheres agreed well with theoretical calculations. Good agreement was also found with simultaneous aerosol extinction measurements at 450, 530, and 630 nm using CAPS PMex instruments in a series of 22 tests including non-absorbing compounds, dusts, soot, and black and brown carbon analogs. SpEx can more accurately distinguish the presence of brown carbon from other absorbing aerosol due to its 300 nm lower wavelength limit compared to measurements limited to visible wavelengths. In addition, the spectra obtained by SpEx carry more information than can be conveyed by a simple power law fit that is typically defined by the use of Angstrom Exponents. Future improvements aim at lowering detection limits and ruggedizing the instrument for mobile operation.

  6. In Situ Aerosol Profile Measurements and Comparisons with SAGE 3 Aerosol Extinction and Surface Area Profiles at 68 deg North

    NASA Technical Reports Server (NTRS)

    2005-01-01

    Under funding from this proposal three in situ profile measurements of stratospheric sulfate aerosol and ozone were completed from balloon-borne platforms. The measured quantities are aerosol size resolved number concentration and ozone. The one derived product is aerosol size distribution, from which aerosol moments, such as surface area, volume, and extinction can be calculated for comparison with SAGE III measurements and SAGE III derived products, such as surface area. The analysis of these profiles and comparison with SAGE III extinction measurements and SAGE III derived surface areas are provided in Yongxiao (2005), which comprised the research thesis component of Mr. Jian Yongxiao's M.S. degree in Atmospheric Science at the University of Wyoming. In addition analysis continues on using principal component analysis (PCA) to derive aerosol surface area from the 9 wavelength extinction measurements available from SAGE III. Ths paper will present PCA components to calculate surface area from SAGE III measurements and compare these derived surface areas with those available directly from in situ size distribution measurements, as well as surface areas which would be derived from PCA and Thomason's algorithm applied to the four wavelength SAGE II extinction measurements.

  7. Characteristics of aerosol size distribution and vertical backscattering coefficient profile during 2014 APEC in Beijing

    NASA Astrophysics Data System (ADS)

    Zhang, Jiaoshi; Chen, Zhenyi; Lu, Yihuai; Gui, Huaqiao; Liu, Jianguo; Liu, Wenqing; Wang, Jie; Yu, Tongzhu; Cheng, Yin; Chen, Yong; Ge, Baozhu; Fan, Yu; Luo, Xisheng

    2017-01-01

    During the 2014 Asia-Pacific Economic Cooperation (APEC) conference period, Beijing's air quality was greatly improved as a result of a series of tough emission control measures being implemented in Beijing and its surrounding provinces. However, a moderate haze occurred during the period of 4-5 November. In order to evaluate the emission control measures and study the formation mechanism of the haze, a comprehensive field observation based on a supersite and a lidar network was carried out from 25 October 2014 to 20 January 2015. By investigating the variations in aerosol number concentration and mean backscattering coefficient before, during and after the APEC period, it was found that number concentration of accumulation mode and coarse mode particles experienced the most significant decrease by 47% and 68%, and mean backscattering coefficient below 1 km decreased by 34% during the APEC period. Being characterized as "rapidly accumulating and rapidly dispersing", the moderate haze occurred during the APEC period was probably initiated by a wind direction change to south and an increase of wind speed to 4 m/s. Sulfur dioxide involved plume nucleation without growth in size as well as a burst of particles ranging between 100 and 300 nm were observed simultaneously during the haze episode. The elevation of sulfur dioxide concentration and particle number concentration was highly correlated with the southerly wind, signifying the contribution of regional transport. It was observed by the lidar network that the aerosol backscattering coefficient increased in sequence among three sites along the southwest pathway, suggesting that aerosols might be transported from the southwest to the northeast of Beijing with a speed of approximately 17 km/h, which agreed with the movement of air masses modeled by Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT). The dual-wavelength lidar (355 and 532 nm) observation suggested that transportation of fine particles

  8. Use of Probability Distribution Functions for Discriminating Between Cloud and Aerosol in Lidar Backscatter Data

    NASA Technical Reports Server (NTRS)

    Liu, Zhaoyan; Vaughan, Mark A.; Winker, Davd M.; Hostetler, Chris A.; Poole, Lamont R.; Hlavka, Dennis; Hart, William; McGill, Mathew

    2004-01-01

    In this paper we describe the algorithm hat 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 and multiple-dimensional probability density functions (PDFs) in the context of a two-class feature identification scheme. From these studies we derive an operational algorithm based on a set of 3-dimensional probability distribution functions characteristic of clouds and aerosols. A dataset acquired by the Cloud Physics Lidar (CPL) is used to test the algorithm. Comparisons are conducted between the CALIPSO algorithm results and the CPL data product. The results obtained show generally good agreement between the two methods. However, of a total of 228,264 layers analyzed, approximately 5.7% are classified as different types by the CALIPSO and CPL algorithm. This disparity is shown to be due largely to the misclassification of clouds as aerosols by the CPL algorithm. The use of 3-dimensional PDFs in the CALIPSO algorithm is found to significantly reduce this type of error. Dust presents a special case. Because the intrinsic scattering properties of dust layers can be very similar to those of clouds, additional algorithm testing was performed using an optically dense layer of Saharan dust measured during the Lidar In-space Technology Experiment (LITE). In general, the method is shown to distinguish reliably between dust layers and clouds. The relatively few erroneous classifications occurred most often in the LITE data, in those regions of the Saharan dust layer where the optical thickness was the highest.

  9. SAGE 1 and SAM 2 measurements of 1 micron aerosol extinction in the free troposphere

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

    The SAGE 1 and SAM 2 satellite sensors were designed to measure, with global coverage, the 1 micron extinction produced by the stratospheric aerosol. In the absence of high altitude cloud, similar measurements may be made for the free tropospheric aerosol. Median extinction values in the Northern Hemisphere, for altitudes between 5 and 10 km, are found to be one-half to one order of magnitude greater than values at corresponding latitudes in the Southern Hemisphere. In addition, a seasonal increase by a factor of 1.5 yields 2 is observed in both hemispheres in local spring and summer. Following major volcanic eruptions, a long-lived enhancement of the aerosol extinction is observed for altitudes above 5 km.

  10. SAGE I and SAM II measurements of 1 micron aerosol extinction in the free troposphere

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

    The SAGE-I and SAM-II satellite sensors were designed to measure, with global coverage, the 1 micron extinction produced by the stratospheric aerosol. In the absence of high altitude clouds, similar measurements may be made for the free tropospheric aerosol. Median extinction values at middle and high latitudes in the Northern Hemisphere, for altitudes between 5 and 10 km, are found to be one-half to one order of magnitude greater than values at corresponding latitudes in the Southern Hemisphere. In addition, a seasonal increase by a factor of 1.5-2 was observed in both hemispheres, in 1979-80, in local spring and summer. Following major volcanic eruptions, a long-lived enhancement of the aerosol extinction is observed for altitudes above 5 km.

  11. Aerosol measurements over the Pacific Ocean in support of the IR aerosol backscatter program

    NASA Technical Reports Server (NTRS)

    Prospero, Joseph M.; Savoie, Dennis L.

    1995-01-01

    The major efforts under NASA contract NAG8-841 included: (1) final analyses of the samples collected during the first GLOBE survey flight that occurred in November 1989 and collections and analysis of aerosol samples during the second GLOBE survey flight in May and June 1990. During the first GLOBE survey flight, daily samples were collected at four stations (Midway, Rarotonga, American Samoa, and Norfolk Island) throughout the month of November 1989. Weekly samples were collected at Shemya, Alaska, and at Karamea, New Zealand. During the second GLOBE survey flight, daily samples were collected at Midway, Oahu, American Samoa, Rarotonga, and Norfolk Island; weekly samples were collected at Shemya. These samples were all analyzed for sodium (sea-salt), chloride, nitrate, sulfate, and methanesulfonate at the University of Miami and for aluminum at the University of Rhode Island (under a subcontract). (2) Samples continued to be collected on a weekly basis at all stations during the periods between and after the survey flights. These weekly samples were also analyzed at the University of Miami for the suite of water-soluble species. (3) In August 1990, the results obtained from the above studies were submitted to the appropriate personnel at NASA Marshall Space Flight Center to become part of the GLOBE data base for comparison with data from instruments used aboard the aircraft. In addition, the data will be compared with data previously obtained at these stations as part of the Sea-Air Exchange (SEAREX) Program. This comparison will provide valuable information on the representativeness of the periods in terms of the longer term aerosol climatology over the Pacific Ocean. (4) Several publications have been written using data from this grant. The data will continue to be used in the future as part of a continuing investigation of the long-term trends and interannual variations in aerosol species concentrations over the Pacific Ocean.

  12. Enhanced extinction of visible radiation due to hydrated aerosols in mist and fog

    NASA Astrophysics Data System (ADS)

    Elias, T.; Dupont, J.-C.; Hammer, E.; Hoyle, C. R.; Haeffelin, M.; Burnet, F.; Jolivet, D.

    2015-06-01

    The study assesses the contribution of aerosols to the extinction of visible radiation in the mist-fog-mist cycle. Relative humidity is large in the mist-fog-mist cycle, and aerosols most efficient in interacting with visible radiation are hydrated and compose the accumulation mode. Measurements of the microphysical and optical properties of these hydrated aerosols with diameters larger than 0.4 μm were carried out near Paris, during November 2011, under ambient conditions. Eleven mist-fog-mist cycles were observed, with a cumulated fog duration of 96 h, and a cumulated mist-fog-mist cycle duration of 240 h. In mist, aerosols grew by taking up water at relative humidities larger than 93%, causing a visibility decrease below 5 km. While visibility decreased down from 5 to a few kilometres, the mean size of the hydrated aerosols increased, and their number concentration (Nha) increased from approximately 160 to approximately 600 cm-3. When fog formed, droplets became the strongest contributors to visible radiation extinction, and liquid water content (LWC) increased beyond 7 mg m-3. Hydrated aerosols of the accumulation mode co-existed with droplets, as interstitial non-activated aerosols. Their size continued to increase, and some aerosols achieved diameters larger than 2.5 μm. The mean transition diameter between the aerosol accumulation mode and the small droplet mode was 4.0 ± 1.1 μm. Nha also increased on average by 60 % after fog formation. Consequently, the mean contribution to extinction in fog was 20 ± 15% from hydrated aerosols smaller than 2.5 μm and 6 ± 7% from larger aerosols. The standard deviation was large because of the large variability of Nha in fog, which could be smaller than in mist or 3 times larger. The particle extinction coefficient in fog can be computed as the sum of a droplet component and an aerosol component, which can be approximated by 3.5 Nha (Nha in cm-3 and particle extinction coefficient in Mm-1. We observed an influence of

  13. 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)

    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

    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.

  14. Application of HARLIE Measurements in Mesoscale Studies: Measurements of Aerosol Backscatter and Winds During A Gust Front

    NASA Technical Reports Server (NTRS)

    Demoz, Belay; Miller, David; Schwemmer, Geary; Starr, David OC (Technical Monitor)

    2001-01-01

    Lidar atmospheric systems have required large telescope for receiving atmospheric backscatter signals. Thus, the relative complexity in size and ease of operation has limited their wider use in the atmospheric science and meteorology community. The Holographic Airborne Rotating Lidar Instrument Experiment (HARLIE) uses a scanning holographic receiver and demonstrates that these issues can be overcome. HARLIE participated at the DOE-ARM Southern Great Plains site (CART) during the Water Vapor Intensive Operation Period (WVIOP2000) held September-October 2000. It provided exceptional high temporal and spatial resolution measurements of aerosol and cloud backscatter in three dimensions. HARLIE recorded over 110 hours of data were recorded on 16 days between 17 September and 6 October 2000. Placed in a ground-based trailer for upward looking scanning measurements of clouds and aerosols, HARLIE provided a unique record of time-resolved atmospheric backscatter at 1-micron wavelength. The conical scanning lidar measures atmospheric backscatter on the surface of an inverted 90 degree (full angle) cone up to an altitude of 20 km, 360-degree scans having spatial resolutions of 20 meters in the vertical and 1 degree in azimuth were obtained every 36 seconds during the daily, operating period. In this study we present highlights of HARLIE-based measurements of the boundary layer and cloud parameters as well as atmospheric wind vectors where there is sufficiently resolved structure in the backscatter. In particular we present data and discussions from a bore-front case observed on 23 September 2000.

  15. Elastic back-scattering patterns via particle surface roughness and orientation from single trapped airborne aerosol particles

    NASA Astrophysics Data System (ADS)

    Fu, Richard; Wang, Chuji; Muñoz, Olga; Videen, Gorden; Santarpia, Joshua L.; Pan, Yong-Le

    2017-01-01

    We demonstrate a method for simultaneously measuring the back-scattering patterns and images of single laser-trapped airborne aerosol particles. This arrangement allows us to observe how the back-scattering patterns change with particle size, shape, surface roughness, orientation, etc. The recoded scattering patterns cover the angular ranges of θ=167.7-180° (including at 180° exactly) and ϕ=0-360° in spherical coordinates. The patterns show that the width of the average speckle intensity islands or rings is inversely proportional to particle size and how the shape of these intensity rings or islands also depends on the surface roughness. For an irregularly shaped particle with substantial roughness, the back-scattering patterns are formed with speckle intensity islands, the size and orientations of these islands depend more on the overall particle size and orientation, but have less relevance to the fine alteration of the surface structure and shapes. The back-scattering intensity at 180° is very sensitive to the particle parameters. It can change from a maximum to a minimum with a change of 0.1% in particle size or refractive index. The method has potential use in characterizing airborne aerosol particles, and may be used to provide back-scattering information for LIDAR applications.

  16. Comparison of aerosol backscatter and wind field estimates from the REAL and the SAMPLE

    NASA Astrophysics Data System (ADS)

    Mayor, Shane D.; Dérian, Pierre; Mauzey, Christopher F.; Spuler, Scott M.; Ponsardin, Patrick; Pruitt, Jeff; Ramsey, Darrell; Higdon, Noah S.

    2015-09-01

    Although operating at the same near-infrared 1.5- m wavelength, the Raman-shifted Eye-safe Aerosol Lidar (REAL) and the Scanning Aerosol Micro-Pulse Lidar-Eye-safe (SAMPLE) are very different in how they generate and detect laser radiation. We present results from an experiment where the REAL and the SAMPLE were operated side-by-side in Chico, California, in March of 2015. During the non-continuous, eleven day test period, the SAMPLE instrument was operated at maximum pulse repetition frequency (15 kHz) and integrated over the interpulse period of the REAL (0.1 s). Operation at the high pulse repetition frequency resulted in second trip echoes which contaminated portions of the data. The performance of the SAMPLE instrument varied with background brightness--as expected with a photon counting receiver|--yet showed equal or larger backscatter intensity signal to noise ratio throughout the intercomparison experiment. We show that a modest low-pass filter or smooth applied to the REAL raw waveforms (that have 5x higher range resolution) results in significant increases in raw signal-to-noise ratio and image signal-to-noise ratio--a measure of coherent aerosol feature content in the images resulting from the scans. Examples of wind fields and time series of wind estimates from both systems are presented. We conclude by reviewing the advantages and disadvantages of each system and sketch a plan for future research and development activities to optimize the design of future systems.

  17. Enhanced extinction of visible radiation due to hydrated aerosols in mist and fog

    NASA Astrophysics Data System (ADS)

    Elias, T.; Dupont, J.-C.; Hammer, E.; Hoyle, C. R.; Haeffelin, M.; Burnet, F.; Jolivet, D.

    2015-01-01

    The study assesses the contribution of aerosols to the extinction of visible radiation in the mist-fog-mist cycle. Measurements of the microphysical and optical properties of hydrated aerosols with diameters larger than 400 nm, composing the accumulation mode, which are the most efficient to interact with visible radiation, were carried out near Paris, during November 2011, in ambient conditions. Eleven mist-fog-mist cycles were observed, with cumulated fog duration of 95 h, and cumulated mist-fog-mist duration of 240 h. In mist, aerosols grew up by taking up water at relative humidities larger than 93%, causing a visibility decrease below 5 km. While visibility decreased down to few km, the mean size of the hydrated aerosols increased, and their number concentration (Nha) increased from approximately 160 to approximately 600 cm-3. When fog formed, droplets became the strongest contributors to visible radiation extinction, and liquid water content (LWC) increased beyond 7 mg m-3. Hydrated aerosols of the accumulation mode co-existed with droplets, as interstitial non-activated aerosols. Their size continued to increase, and a significant proportion of aerosols achieved diameters larger than 2.5 μm. The mean transition diameter between the accumulation mode and the small droplet mode was 4.0 ± 1.1 μm. Moreover Nha increased on average by 60% after fog formation. Consequently the mean aerosol contribution to extinction in fog was 20 ± 15% for diameter smaller than 2.5 μm and 6 ± 7% beyond. The standard deviation is large because of the large variability of Nha in fog, which could be smaller than in mist or three times larger. The particle extinction coefficient in fog can be computed as the sum of a droplet component and an aerosol component, which can be approximated by 3.5 Nha (Nha in cm-3 and particle extinction coefficient in Mm-1). We observed an influence of the main formation process on Nha, but not on the contribution to fog extinction by aerosols

  18. Calculation of aerosol backscatter from airborne continuous wave focused CO2 Doppler lidar measurements. I - Algorithm description

    NASA Technical Reports Server (NTRS)

    Rothermel, Jeffry; Bowdle, David A.; Vaughan, Michael; Brown, Derek W.; Woodfield, Alan A.

    1991-01-01

    Since 1981 the Royal Signals and Radar Establishment and the Royal Aircraft Establishment, United Kindom, have made vertical and horizontal sounding measurements of aerosol backscatter coefficients at 10.6 microns, using an airborne continuous-wave-focused CO2 Doppler lidar, the Laser True Airspeed System (LATAS). In this paper, the heterodyne signal from the LATAS detector is spectrally analyzed. Then, in conjunction with aircraft flight parameters, the data are processed in a six-stage computer algorithm: set search window, search for peak signal, test peak signal, measure total signal, calculate signal-to-noise ratio, and calculate backscatter coefficient.

  19. A Laboratory Investigation of Aerosol and Extinction Characteristics for SALTY DOG, NWC 29 and NWC 78 Pyrotechnics

    DTIC Science & Technology

    1980-10-01

    Dispersion Extinction Pyrotechnics Salty Dog Smokes Deliquescent Growth i *0. ABSTRACT (Continue on reverse aide Iti nee.,ary and idently by block... deliquescent aerosol. Results from the laboratory investigation of individual particle growth indicate that the aerosol generated by NVC 78 has the...due to liquid water (i.e., the deliquesced aerosol) absorption at those IR wavelengths. To compare the extinction effectiveness of Salty Dog to that of

  20. Light extinction by aerosols during summer air pollution

    NASA Technical Reports Server (NTRS)

    Kaufman, Y. J.; Fraser, R. S.

    1983-01-01

    In order to utilize satellite measurements of optical thickness over land for estimating aerosol properties during air pollution episodes, the optical thickness was measured from the surface and investigated. Aerosol optical thicknesses have been derived from solar transmission measurements in eight spectral bands within the band lambda 440-870 nm during the summers of 1980 and 1981 near Washington, DC. The optical thicknesses for the eight bands are strongly correlated. It was found that first eigenvalue of the covariance matrix of all observations accounts for 99 percent of the trace of the matrix. Since the measured aerosol optical thickness was closely proportional to the wavelength raised to a power, the aerosol size distribution derived from it is proportional to the diameter (d) raised to a power for the range of diameters between 0.1 to 1.0 micron. This power is insensitive to the total optical thickness. Changes in the aerosol optical thickness depend on several aerosol parameters, but it is difficult to identify the dominant one. The effects of relative humidity and accumulation mode concentration on the optical thickness are analyzed theoretically, and compared with the measurements.

  1. Inter-Comparison of ILAS-II Version 1.4 Aerosol Extinction Coefficient at 780 nm with SAGE II, SAGE III, and POAM III Aerosol Data

    NASA Technical Reports Server (NTRS)

    Saitoh, Naoko; Hayashida, S.; Sugita, T.; Nakajima, H.; Yokota, T.; Hayashi, M.; Shiraishi, K.; Kanzawa, H.; Ejiri, M. K.; Irie, H.; Tanaka, T.; Terao, Y.; Kobayashi, H.; Sasano, Y.; Bevilacqua, R.; Randall, C.; Thomason, L.; Taha, G.

    2006-01-01

    The Improved Limb Atmospheric Spectrometer (ILAS) II on board the Advanced Earth Observing Satellite (ADEOS) II observed stratospheric aerosol in visible/near-infrared/infrared spectra over high latitudes in the Northern and Southern Hemispheres. Observations were taken intermittently from January to March, and continuously from April through October, 2003. We assessed the data quality of ILAS-II version 1.4 aerosol extinction coefficients at 780 nm from comparisons with the Stratospheric Aerosol and Gas Experiment (SAGE) II, SAGE III, and the Polar Ozone and Aerosol Measurement (POAM) III aerosol data. At heights below 20 km in the Northern Hemisphere, aerosol extinction coefficients from ILAS-II agreed with those from SAGE II and SAGE III within 10%, and with those from POAM III within 15%. From 20 to 26 km, ILAS-II aerosol extinction coefficients were smaller than extinction coefficients from the other sensors; differences between ILAS-II and SAGE II ranged from 10% at 20 km to 34% at 26 km. ILAS-II aerosol extinction coefficients from 20 to 25 km in February over the Southern Hemisphere had a negative bias (12-66%) relative to SAGE II aerosol data. The bias increased with increasing altitude. Comparisons between ILAS-II and POAM III aerosol extinction coefficients from January to May in the Southern Hemisphere (defined as the non-Polar Stratospheric Cloud (PSC) season ) yielded qualitatively similar results. From June to October (defined as the PSC season ), aerosol extinction coefficients from ILAS-II were smaller than those from POAM III above 17 km, as in the case of the non-PSC season; however, ILAS-II and POAM III aerosol data were within 15% of each other from 12 to 17 km.

  2. Characterizing the Vertical Profile of Aerosol Particle Extinction and Linear Depolarization over Southeast Asia and the Maritime Continent: The 2007-2009 View from CALIOP

    NASA Technical Reports Server (NTRS)

    Campbell, James R.; Reid, Jeffrey S.; Westphal, Douglas L.; Zhang, Jianglong; Tackett, Jason L.; Chew, Boon Ning; Welton, Ellsworth J.; Shimizu, Atsushi; Sugimoto, Nobuo; Aoki, Kazuma; Winker, David M.

    2012-01-01

    Vertical profiles of 0.532 µm aerosol particle extinction coefficient and linear volume depolarization ratio are described for Southeast Asia and the Maritime Continent. Quality-screened and cloud-cleared Version 3.01 Level 2 NASA Cloud Aerosol Lidar with Orthogonal Polarization (CALIOP) 5-km Aerosol Profile datasets are analyzed from 2007 to 2009. Numerical simulations from the U.S. Naval Aerosol Analysis and Predictive System (NAAPS), featuring two-dimensional variational assimilation of NASA Moderate Resolution Imaging Spectroradiometer and Multi-angle Imaging Spectro- Radiometer quality-assured datasets, combined with regional ground-based lidar measurements, are considered for assessing CALIOP retrieval performance, identifying bias, and evaluating regional representativeness. CALIOP retrievals of aerosol particle extinction coefficient and aerosol optical depth (AOD) are high over land and low over open waters relative to NAAPS (0.412/0.312 over land for all data points inclusive, 0.310/0.235 when the per bin average is used and each is treated as single data points; 0.102/0.151 and 0.086/0.124, respectively, over ocean). Regional means, however, are very similar (0.180/0.193 for all data points and 0.155/0.159 when averaged per normalized bin), as the two factors offset one another. The land/ocean offset is investigated, and discrepancies attributed to interpretation of particle composition and a-priori assignment of the extinction-to-backscatter ratio ("lidar ratio") necessary for retrieving the extinction coefficient from CALIOP signals. Over land, NAAPS indicates more dust present than CALIOP algorithms are identifying, indicating a likely assignment of a higher lidar ratio representative of more absorptive particles. NAAPS resolvesmore smoke overwater than identified with CALIOP, indicating likely usage of a lidar ratio characteristic of less absorptive particles to be applied that biases low AOD there. Over open waters except within the Bay of Bengal

  3. Characterizing the vertical profile of aerosol particle extinction and linear depolarization over Southeast Asia and the Maritime Continent: The 2007-2009 view from CALIOP

    NASA Astrophysics Data System (ADS)

    Campbell, James R.; Reid, Jeffrey S.; Westphal, Douglas L.; Zhang, Jianglong; Tackett, Jason L.; Chew, Boon Ning; Welton, Ellsworth J.; Shimizu, Atsushi; Sugimoto, Nobuo; Aoki, Kazuma; Winker, David M.

    2013-03-01

    Vertical profiles of 0.532 μm aerosol particle extinction coefficient and linear volume depolarization ratio are described for Southeast Asia and the Maritime Continent. Quality-screened and cloud-cleared Version 3.01 Level 2 NASA Cloud Aerosol Lidar with Orthogonal Polarization (CALIOP) 5-km Aerosol Profile datasets are analyzed from 2007 to 2009. Numerical simulations from the U.S. Naval Aerosol Analysis and Predictive System (NAAPS), featuring two-dimensional variational assimilation of NASA Moderate Resolution Imaging Spectroradiometer and Multi-angle Imaging SpectroRadiometer quality-assured datasets, combined with regional ground-based lidar measurements, are considered for assessing CALIOP retrieval performance, identifying bias, and evaluating regional representativeness. CALIOP retrievals of aerosol particle extinction coefficient and aerosol optical depth (AOD) are high over land and low over open waters relative to NAAPS (0.412/0.312 over land for all data points inclusive, 0.310/0.235 when the per bin average is used and each is treated as single data points; 0.102/0.151 and 0.086/0.124, respectively, over ocean). Regional means, however, are very similar (0.180/0.193 for all data points and 0.155/0.159 when averaged per normalized bin), as the two factors offset one another. The land/ocean offset is investigated, and discrepancies attributed to interpretation of particle composition and a-priori assignment of the extinction-to-backscatter ratio (“lidar ratio”) necessary for retrieving the extinction coefficient from CALIOP signals. Over land, NAAPS indicates more dust present than CALIOP algorithms are identifying, indicating a likely assignment of a higher lidar ratio representative of more absorptive particles. NAAPS resolves more smoke over water than identified with CALIOP, indicating likely usage of a lidar ratio characteristic of less absorptive particles to be applied that biases low AOD there. Over open waters except within the Bay of

  4. Stratospheric Aerosol and Gas Experiment (SAGE) II and III Aerosol Extinction Measurements in the Arctic Middle and Upper Troposphere

    NASA Technical Reports Server (NTRS)

    Treffeisen, R. E.; Thomason, L. W.; Strom, J.; Herber, A. B.; Burton, S. P.; Yamanouchi, T.

    2006-01-01

    In recent years, substantial effort has been expended toward understanding the impact of tropospheric aerosols on Arctic climate and chemistry. A significant part of this effort has been the collection and documentation of extensive aerosol physical and optical property data sets. However, the data sets present significant interpretive challenges because of the diverse nature of these measurements. Among the longest continuous records is that by the spaceborne Stratospheric Aerosol and Gas Experiment (SAGE) II. Although SAGE tropospheric measurements are restricted to the middle and upper troposphere, they may be able to provide significant insight into the nature and variability of tropospheric aerosol, particularly when combined with ground and airborne observations. This paper demonstrates the capacity of aerosol products from SAGE II and its follow-on experiment SAGE III to describe the temporal and vertical variations of Arctic aerosol characteristics. We find that the measurements from both instruments are consistent enough to be combined. Using this combined data set, we detect a clear annual cycle in the aerosol extinction for the middle and upper Arctic troposphere.

  5. MAX-DOAS retrieval of aerosol extinction properties in Madrid, Spain

    NASA Astrophysics Data System (ADS)

    Wang, Shanshan; Cuevas, Carlos A.; Frieß, Udo; Saiz-Lopez, Alfonso

    2016-10-01

    Multi-axis differential optical absorption spectroscopy (MAX-DOAS) measurements were performed in the urban environment of Madrid, Spain, from March to September 2015. The O4 absorption in the ultraviolet (UV) spectral region was used to retrieve the aerosol extinction profile using an inversion algorithm. The results show a good agreement between the hourly retrieved aerosol optical depth (AOD) and the correlative Aerosol Robotic Network (AERONET) product, with a correlation coefficient of R = 0.87. Higher AODs are found in the summer season due to the more frequent occurrence of Saharan dust intrusions. The surface aerosol extinction coefficient as retrieved by the MAX-DOAS measurements was also compared to in situ PM2.5 concentrations. The level of agreement between both measurements indicates that the MAX-DOAS retrieval has the ability to characterize the extinction of aerosol particles near the surface. The retrieval algorithm was also used to study a case of severe dust intrusion on 12 May 2015. The capability of the MAX-DOAS retrieval to recognize the dust event including an elevated particle layer is investigated along with air mass back-trajectory analysis.

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

    NASA Technical Reports Server (NTRS)

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

    1999-01-01

    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.

  7. Remote Sensing of Aerosol Backscatter and Earth Surface Targets By Use of An Airborne Focused Continuous Wave CO2 Doppler Lidar Over Western North America

    NASA Technical Reports Server (NTRS)

    Jarzembski, Maurice A.; Srivastava, Vandana; Goodman, H. Michael (Technical Monitor)

    2000-01-01

    Airborne lidar systems are used to determine wind velocity and to measure aerosol or cloud backscatter variability. Atmospheric aerosols, being affected by local and regional sources, show tremendous variability. Continuous wave (cw) lidar can obtain detailed aerosol loading with unprecedented high resolution (3 sec) and sensitivity (1 mg/cubic meter) as was done during the 1995 NASA Multi-center Airborne Coherent Atmospheric Wind Sensor (MACAWS) mission over western North America and the Pacific Ocean. Backscatter variability was measured at a 9.1 micron wavelength cw focused CO2 Doppler lidar for approximately 52 flight hours, covering an equivalent horizontal distance of approximately 30,000 km in the troposphere. Some quasi-vertical backscatter profiles were also obtained during various ascents and descents at altitudes that ranged from approximately 0.1 to 12 km. Similarities and differences for aerosol loading over land and ocean were observed. Mid-tropospheric aerosol backscatter background mode was approximately 6 x 10(exp -11)/ms/r, consistent with previous lidar datasets. While these atmospheric measurements were made, the lidar also retrieved a distinct backscatter signal from the Earth's surface from the unfocused part of the focused cw lidar beam during aircraft rolls. Atmospheric backscatter can be highly variable both spatially and temporally, whereas, Earth-surface backscatter is relatively much less variant and can be quite predictable. Therefore, routine atmospheric backscatter measurements by an airborne lidar also give Earth surface backscatter which can allow for investigating the Earth terrain. In the case where the Earth's surface backscatter is coming from a well-known and fairly uniform region, then it can potentially offer lidar calibration opportunities during flight. These Earth surface measurements over varying Californian terrain during the mission were compared with laboratory backscatter measurements using the same lidar of various

  8. SAGE II aerosol correlative observations - Profile measurements

    NASA Technical Reports Server (NTRS)

    Osborn, M. T.; Rosen, J. M.; Mccormick, M. P.; Wang, Pi-Huan; Livinfston, J. M.

    1989-01-01

    Profiles of the aerosol extinction measurements from the Stratospheric Aerosol and Gas Experiment (SAGE) II are compared with profiles from five correlative experiments between November 1984 and July 1986. The correlative profiles were derived from six-channel dustsonde measurements and two-wavelength lidar backscatter data. The correlation between the dustsonde- and lidar-derived measurements and the SAGE II data is good, validating the SAGE II lower stratospheric aerosol extinction measurements.

  9. Radiative properties of the background aerosol: absorption component of extinction.

    PubMed

    Clarke, A D; Charlson, R J

    1985-07-19

    The light-scattering and light-absorption coefficients of the global background aerosol define its single-scatter albedo. Continuous, simultaneous measurements of these optical coefficients were made on a daily basis for the remote marine mid-troposphere; such measurements are essential for assessment of the effects of aerosol on atmospheric radiative transfer. Measurements of light-absorption coefficients made at the Mauna Loa Observatory in Hawaii were higher than expected, and the single-scatter albedo was lower than the value often used in radiative transfer models. Soot appears to be the most likely primary absorber, and hemispheric dispersal of this combustion-derived material is suggested.

  10. Simulation of Cloud-aerosol Lidar with Orthogonal Polarization (CALIOP) Attenuated Backscatter Profiles Using the Global Model of Aerosol Processes (GLOMAP)

    NASA Astrophysics Data System (ADS)

    Young, Stuart; Cope, Martin; Lee, Sunhee; Emmerson, Kathryn; Woodhouse, Matthew; Bellouin, Nicolas

    2016-06-01

    To permit the calculation of the radiative effects of atmospheric aerosols, we have linked our aerosol-chemical transport model (CTMGLOMAP) to a new radiation module (UKCARADAER). In order to help assess and improve the accuracy of the radiation code, in particular the height dependence of the predicted scattering, we have developed a module that simulates attenuated backscatter (ABS) profiles that would be measured by the satellite-borne Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) if it were to sample an atmosphere with the same aerosol loading as predicted by the CTM. Initial results of our comparisons of the predicted ABS profiles with actual CALIOP data are encouraging but some differences are noted, particularly in marine boundary layers where the scattering is currently under-predicted and in dust layers where it is often over-predicted. The sources of these differences are being investigated.

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

    NASA Astrophysics Data System (ADS)

    Strawbridge, K. B.

    2013-03-01

    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

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

    NASA Astrophysics Data System (ADS)

    Strawbridge, K. B.

    2012-11-01

    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

  13. Measurements of aerosol phase function and vertical backscattering coefficient using a charge-coupled device side-scatter lidar.

    PubMed

    Tao, Zongming; Liu, Dong; Wang, Zhenzhu; Ma, Xiaomin; Zhang, Qingze; Xie, Chenbo; Bo, Guangyu; Hu, Shunxing; Wang, Yingjian

    2014-01-13

    By using a charge-coupled device (CCD) as the detector, side-scatter lidar has great potential applications in the near range atmospheric detection. A new inversion method is proposed for CCD side-scatter lidar (Clidar) to retrieve aerosol phase function and vertical backscattering coefficient. Case studies show the retrieved results from Clidar are in good agreements with those obtained from other instruments. It indicates that the new proposed inversion method is reliable and feasible and that the Clidar is practicable.

  14. Daytime aerosol extinction profiles from the combination of CALIOP profiles and AERONET products

    NASA Astrophysics Data System (ADS)

    Marcos, C.; Pedrós, R.; Gómez-Amo, J. L.; Sicard, M.; Utrillas, M. P.; Muñoz, C.; Comerón, A.; Martinez-Lozano, J. A.

    2013-04-01

    The solar background illumination has a strong effect on CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) measurements, leading to a decrease in the signal-to-noise ratio of the lidar signal. Because of this, CALIOP level 2 data algorithms might be limited in the retrieval of the properties of the aerosols in the atmosphere. In this work, we present a methodology that combines CALIOP level 1 data with AERONET (Aerosol RObotic NETwork) measurements to retrieve aerosol extinction profiles and lidar ratios in daytime conditions. In this way, we fulfill a two-fold objective: first, we obtain more accurate daytime aerosol information; second, we supplement column integrated measurements from AERONET sun photometers with information about the vertical distribution of aerosols. The methodology has been applied to Burjassot (39.30° N, 0.25° W) and Barcelona (41.39° N, 2.11° E) AERONET stations in the Mediterranean coast of Spain in the period from June 2006 to September 2011. We have found good agreement for the extinction profiles in several study cases of ground lidar measurements in Barcelona, coincident with CALIOP overpasses. Finally, the methodology has proved to be useful for the study of special episodes such as Saharan dust outbreaks.

  15. Using high time resolution aerosol and number size distribution measurements to estimate atmospheric extinction.

    PubMed

    Malm, William C; McMeeking, Gavin R; Kreidenweis, Sonia M; Levin, Ezra; Carrico, Christian M; Day, Derek E; Collett, Jeffrey L; Lee, Taehyoung; Sullivan, Amy P; Raja, Suresh

    2009-09-01

    Rocky Mountain National Park is experiencing reduced visibility and changes in ecosystem function due to increasing levels of oxidized and reduced nitrogen. The Rocky Mountain Atmospheric Nitrogen and Sulfur (RoMANS) study was initiated to better understand the origins of sulfur and nitrogen species as well as the complex chemistry occurring during transport from source to receptor. As part of the study, a monitoring program was initiated for two 1-month time periods--one during the spring and the other during late summer/fall. The monitoring program included intensive high time resolution concentration measurements of aerosol number size distribution, inorganic anions, and cations, and 24-hr time resolution of PM2.5 and PM10 mass, sulfate, nitrate, carbon, and soil-related elements concentrations. These data are combined to estimate high time resolution concentrations of PM2.5 and PM10 aerosol mass and fine mass species estimates of ammoniated sulfate, nitrate, and organic and elemental carbon. Hour-by-hour extinction budgets are calculated by using these species concentration estimates and measurements of size distribution and assuming internal and external particle mixtures. Summer extinction was on average about 3 times higher than spring extinction. During spring months, sulfates, nitrates, carbon mass, and PM10 - PM2.5 mass contributed approximately equal amounts of extinction, whereas during the summer months, carbonaceous material extinction was 2-3 times higher than other species.

  16. Measurement of wavelength-dependent extinction to distinguish between absorbing and nonabsorbing aerosol particulates

    NASA Technical Reports Server (NTRS)

    Portscht, R.

    1977-01-01

    Measurements of spectral transmission factors in smoky optical transmission paths reveal a difference between wavelength exponents of the extinction cross section of high absorption capacity and those of low absorption capacity. A theoretical explanation of this behavior is presented. In certain cases, it is possible to obtain data on the absorption index of aerosol particles in the optical path by measuring the spectral decadic extinction coefficient at, at least, two wavelengths. In this manner it is possible, for instance, to distinguish smoke containing soot from water vapor.

  17. Boundary Layer Aerosol Composition over Sierra Nevada Mountains using 9.11- and 10.59-micron CW Lidars and Modeled Backscatter from Size Distribution Data

    NASA Technical Reports Server (NTRS)

    Cutten, D. R.; Jarzembski, M. A.; Srivastava, V.; Pueschel, R. F.; Howard, S. D.; McCaul, E. W., Jr.

    2003-01-01

    An inversion technique has been developed to determine volume fractions of an atmospheric aerosol composed primarily of ammonium sulfate and ammonium nitrate and water combined with fixed concentration of elemental and organic carbon. It is based on measured aerosol backscatter obtained with 9.11 - and 10.59-micron wavelength continuous wave CO2 lidars and modeled backscatter from aerosol size distribution data. The technique is demonstrated during a flight of the NASA DC-8 aircraft over the Sierra Nevada Mountain Range, California on 19 September, 1995. Volume fraction of each component and effective complex refractive index of the composite particle were determined assuming an internally mixed composite aerosol model. The volume fractions were also used to re-compute aerosol backscatter, providing good agreement with the lidar-measured data. The robustness of the technique for determining volume fractions was extended with a comparison of calculated 2.1,-micron backscatter from size distribution data with the measured lidar data converted to 2.1,-micron backscatter using an earlier derived algorithm, verifying the algorithm as well as the backscatter calculations.

  18. 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)

    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

    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.

  19. Comparison of vertical aerosol extinction coefficients from in-situ and LIDAR measurements

    NASA Astrophysics Data System (ADS)

    Rosati, B.; Herrmann, E.; Bucci, S.; Fierli, F.; Cairo, F.; Gysel, M.; Tillmann, R.; Größ, J.; Gobbi, G. P.; Di Liberto, L.; Di Donfrancesco, G.; Wiedensohler, A.; Weingartner, E.; Virtanen, A.; Mentel, T. F.; Baltensperger, U.

    2015-07-01

    Vertical profiles of aerosol optical properties were explored in a case study near the San Pietro Capofiume (SPC) ground station during the PEGASOS Po Valley campaign in the summer of 2012. A Zeppelin NT airship was employed to investigate the effect of the dynamics of the planetary boundary layer at altitudes between ~ 50-800 m above ground. Determined properties included the aerosol size distribution, the hygroscopic growth factor, the effective index of refraction and the light absorption coefficient. The first three parameters were used to retrieve the light scattering coefficient. Simultaneously, direct measurements of both the scattering and absorption coefficient were carried out at the SPC ground station. Additionally, a LIDAR system provided aerosol extinction coefficients for a vertically resolved comparison between in-situ and remote sensing results. First, the airborne results at low altitudes were validated with the ground measurements. Agreement within approximately ±25 and ±20% was found for the dry scattering and absorption coefficient, respectively. The single scattering albedo, ranged between 0.83 to 0.95, indicating the importance of the absorbing particles in the Po Valley region. A clear layering of the atmosphere was observed during the beginning of the flight (until ~ 10 local time) before the mixed layer (ML) was fully developed. Highest extinction coefficients were found at low altitudes, in the new ML, while values in the residual layer, which could be probed at the beginning of the flight at elevated altitudes, were lower. At the end of the flight (after ~ 12 local time) the ML was fully developed, resulting in constant extinction coefficients at all altitudes measured on the Zeppelin NT. LIDAR results captured these dynamic features well and good agreement was found for the extinction coefficients compared to the in-situ results, using fixed LIDAR ratios (LR) between 30 and 70 sr for the altitudes probed with the Zeppelin. These LR are

  20. The impacts of aerosol loading, composition, and water uptake on aerosol extinction variability in the Baltimore-Washington, D.C. region

    NASA Astrophysics Data System (ADS)

    Beyersdorf, A. J.; Ziemba, L. D.; Chen, G.; Corr, C. A.; Crawford, J. H.; Diskin, G. S.; Moore, R. H.; Thornhill, K. L.; Winstead, E. L.; Anderson, B. E.

    2016-01-01

    In order to utilize satellite-based aerosol measurements for the determination of air quality, the relationship between aerosol optical properties (wavelength-dependent, column-integrated extinction measured by satellites) and mass measurements of aerosol loading (PM2.5 used for air quality monitoring) must be understood. This connection varies with many factors including those specific to the aerosol type - such as composition, size, and hygroscopicity - and to the surrounding atmosphere, such as temperature, relative humidity (RH), and altitude, all of which can vary spatially and temporally. During the DISCOVER-AQ (Deriving Information on Surface conditions from Column and Vertically Resolved Observations Relevant to Air Quality) project, extensive in situ atmospheric profiling in the Baltimore, MD-Washington, D.C. region was performed during 14 flights in July 2011. Identical flight plans and profile locations throughout the project provide meaningful statistics for determining the variability in and correlations between aerosol loading, composition, optical properties, and meteorological conditions. Measured water-soluble aerosol mass was composed primarily of ammonium sulfate (campaign average of 32 %) and organics (57 %). A distinct difference in composition was observed, with high-loading days having a proportionally larger percentage of sulfate due to transport from the Ohio River Valley. This composition shift caused a change in the aerosol water-uptake potential (hygroscopicity) such that higher relative contributions of inorganics increased the bulk aerosol hygroscopicity. These days also tended to have higher relative humidity, causing an increase in the water content of the aerosol. Conversely, low-aerosol-loading days had lower sulfate and higher black carbon contributions, causing lower single-scattering albedos (SSAs). The average black carbon concentrations were 240 ng m-3 in the lowest 1 km, decreasing to 35 ng m-3 in the free troposphere (above

  1. SAGE III Aerosol Extinction Validation in the Arctic Winter: Comparisons with SAGE II and POAM III

    NASA Technical Reports Server (NTRS)

    Thomason, L. W.; Poole, L. R.; Randall, C. E.

    2007-01-01

    The use of SAGE III multiwavelength aerosol extinction coefficient measurements to infer PSC type is contingent on the robustness of both the extinction magnitude and its spectral variation. Past validation with SAGE II and other similar measurements has shown that the SAGE III extinction coefficient measurements are reliable though the comparisons have been greatly weighted toward measurements made at mid-latitudes. Some aerosol comparisons made in the Arctic winter as a part of SOLVE II suggested that SAGE III values, particularly at longer wavelengths, are too small with the implication that both the magnitude and the wavelength dependence are not reliable. Comparisons with POAM III have also suggested a similar discrepancy. Herein, we use SAGE II data as a common standard for comparison of SAGE III and POAM III measurements in the Arctic winters of 2002/2003 through 2004/2005. During the winter, SAGE II measurements are made infrequently at the same latitudes as these instruments. We have mitigated this problem through the use potential vorticity as a spatial coordinate and thus greatly increased the number of coincident events. We find that SAGE II and III extinction coefficient measurements show a high degree of compatibility at both 1020 nm and 450 nm except a 10-20% bias at both wavelengths. In addition, the 452 to 1020-nm extinction ratio shows a consistent bias of approx. 30% throughout the lower stratosphere. We also find that SAGE II and POAM III are on average consistent though the comparisons show a much higher variability and larger bias than SAGE II/III comparisons. In addition, we find that the two data sets are not well correlated below 18 km. Overall, we find both the extinction values and the spectral dependence from SAGE III are robust and we find no evidence of a significant defect within the Arctic vortex.

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

    PubMed

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

    2013-02-11

    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.

  3. An effective inversion algorithm for retrieving bimodal aerosol particle size distribution from spectral extinction data

    NASA Astrophysics Data System (ADS)

    He, Zhenzong; Qi, Hong; Yao, Yuchen; Ruan, Liming

    2014-12-01

    The Ant Colony Optimization algorithm based on the probability density function (PDF-ACO) is applied to estimate the bimodal aerosol particle size distribution (PSD). The direct problem is solved by the modified Anomalous Diffraction Approximation (ADA, as an approximation for optically large and soft spheres, i.e., χ≫1 and |m-1|≪1) and the Beer-Lambert law. First, a popular bimodal aerosol PSD and three other bimodal PSDs are retrieved in the dependent model by the multi-wavelength extinction technique. All the results reveal that the PDF-ACO algorithm can be used as an effective technique to investigate the bimodal PSD. Then, the Johnson's SB (J-SB) function and the modified beta (M-β) function are employed as the general distribution function to retrieve the bimodal PSDs under the independent model. Finally, the J-SB and M-β functions are applied to recover actual measurement aerosol PSDs over Beijing and Shanghai obtained from the aerosol robotic network (AERONET). The numerical simulation and experimental results demonstrate that these two general functions, especially the J-SB function, can be used as a versatile distribution function to retrieve the bimodal aerosol PSD when no priori information about the PSD is available.

  4. Aerosol extinction properties over coastal West Bengal Gangetic plain under inter-seasonal and sea breeze influenced transport processes

    NASA Astrophysics Data System (ADS)

    Verma, S.; Priyadharshini, B.; Pani, S. K.; Bharath Kumar, D.; Faruqi, A. R.; Bhanja, S. N.; Mandal, M.

    2016-01-01

    We analysed the atmospheric aerosol extinction properties under an influence of inter-seasonal and sea breeze (SB) transport processes over coastal West Bengal (WB) Gangetic plain (WBGP). The predominant frequency of airmass back trajectory path was through the Arabian Sea (AS) during southwest monsoon (SWmon) and that through the Indo-Gangetic plain (IGP) during transition to winter (Twin) season and the Bay of Bengal during transition to summer (Tsumm) season. Aerosol surface concentration (Sconc) and aerosol extinction exhibited heterogeneity in the seasonal variability over coastal WBGP with their highest seasonal mean being during winter and summer seasons respectively. Seasonal mean extinction was respectively 17% and 30% higher during winter and summer seasons than that during SWmon. While angstrom exponent (AE) was less than one during SWmon, Tsumm, and summer seasons, it was near to one during Twin and winter monsoon (Wmon), and was more than one during winter season. Relative contribution (%) of upper (at altitude above 1 km) aerosol layer (UAL) to aerosol extinction during summer was four times of that during winter. Seasonally distinct vertical distribution of aerosol extinction associated with meteorological and SB influenced transport and that due to influence of high rise open burning emissions was inferred. Possible aerosol subtypes extracted during days in Tsumm were inferred to be mostly constituted of dust and polluted dust during daytime, in addition to polluted continental and smoke in UAL during nighttime. In contrast to that at nearby urban location (Kolkata, KOL), intensity of updraft of airmass evaluated during evening/SB activity hour (1730 local time, (LT)) at study site (Kharagpur, KGP) was as high as 3.5 times the intensity during near to noon hour (1130 LT); this intensity was the highest along coast of westBengal-Orissa. Enhanced Sconc and relative contribution of UAL to aerosol extinction (58% compared to 36% only at nearby urban

  5. 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)

    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

    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).

  6. Modeling of growth and evaporation effects on the extinction of 1.0-micron solar radiation traversing stratospheric sulfuric acid aerosols

    NASA Technical Reports Server (NTRS)

    Yue, G. K.; Deepak, A.

    1981-01-01

    The effects of growth and evaporation of stratospheric sulfuric acid aerosols on the extinction of solar radiation traversing such an aerosol medium are reported for the case of 1.0-micron solar radiation. Modeling results show that aerosol extinction is not very sensitive to the change of ambient water vapor concentration, but is sensitive to ambient temperature changes, especially at low ambient temperatures and high ambient water vapor concentration. A clarification is given of the effects of initial aerosol size distribution and composition on the change of aerosol extinction due to growth and evaporation processes. It is shown that experiments designed to observe solar radiation extinction of aerosols may also be applied to the determination of observed changes in aerosol optical properties, environmental parameters, or the physical and optical characteristics of sulfate aerosols.

  7. Optical and Physicochemical Properties of Brown Carbon Aerosol: Light Scattering, FTIR Extinction Spectroscopy, and Hygroscopic Growth.

    PubMed

    Tang, Mingjin; Alexander, Jennifer M; Kwon, Deokhyeon; Estillore, Armando D; Laskina, Olga; Young, Mark A; Kleiber, Paul D; Grassian, Vicki H

    2016-06-23

    A great deal of attention has been paid to brown carbon aerosol in the troposphere because it can both scatter and absorb solar radiation, thus affecting the Earth's climate. However, knowledge of the optical and chemical properties of brown carbon aerosol is still limited. In this study, we have investigated different aspects of the optical properties of brown carbon aerosol that have not been previously explored. These properties include extinction spectroscopy in the mid-infrared region and light scattering at two different visible wavelengths, 532 and 402 nm. A proxy for atmospheric brown carbon aerosol was formed from the aqueous reaction of ammonium sulfate with methylglyoxal. The different optical properties were measured as a function of reaction time for a period of up to 19 days. UV/vis absorption experiments of bulk solutions showed that the optical absorption of aqueous brown carbon solution significantly increases as a function of reaction time in the spectral range from 200 to 700 nm. The analysis of the light scattering data, however, showed no significant differences between ammonium sulfate and brown carbon aerosol particles in the measured scattering phase functions, linear polarization profiles, or the derived real parts of the refractive indices at either 532 or 402 nm, even for the longest reaction times with greatest visible extinction. The light scattering experiments are relatively insensitive to the imaginary part of the refractive index, and it was only possible to place an upper limit of k ≤ 0.01 on the imaginary index values. These results suggest that after the reaction with methylglyoxal the single scattering albedo of ammonium sulfate aerosol is significantly reduced but that the light scattering properties including the scattering asymmetry parameter, which is a measure of the relative amount of forward-to-backward scattering, remain essentially unchanged from that of unprocessed ammonium sulfate. The optical extinction properties

  8. Retrievals of atmospheric CO2 from simulated space-borne measurements of backscattered near-infrared sunlight: accounting for aerosol effects.

    PubMed

    Butz, André; Hasekamp, Otto P; Frankenberg, Christian; Aben, Ilse

    2009-06-20

    Retrievals of atmospheric carbon dioxide (CO2) from space-borne measurements of backscattered near-infrared sunlight are hampered by aerosol and cirrus cloud scattering effects. We propose a retrieval approach that allows for the retrieval of a few effective aerosol parameters simultaneously with the CO2 total column by parameterizing particle amount, height distribution, and microphysical properties. Two implementations of the proposed method covering different spectral bands are tested for an ensemble of simulated nadir observations for aerosol (and cirrus) loaded scenes over low- and mid-latitudinal land surfaces. The residual aerosol-induced CO(2) errors are mostly below 1% up to aerosol optical thickness 0.5. The proposed methods also perform convincing for scenes where cirrus clouds of optical thickness 0.1 overlay the aerosol.

  9. Infrared extinction spectra of mineral dust aerosol: Single components and complex mixtures

    NASA Astrophysics Data System (ADS)

    Laskina, Olga; Young, Mark A.; Kleiber, Paul D.; Grassian, Vicki H.

    2012-09-01

    Simultaneous Fourier transform infrared (FTIR) extinction spectra and aerosol size distributions have been measured for some components of mineral dust aerosol including feldspars (albite, oligoclase) and diatomaceous earth, as well as more complex authentic dust samples that include Iowa loess and Saharan sand. Spectral simulations for single-component samples, derived from Rayleigh-theory models for characteristic particle shapes, better reproduce the experimental spectra including the peak position and band shape compared to Mie theory. The mineralogy of the authentic dust samples was inferred using analysis of FTIR spectra. This approach allows for analysis of the mineralogy of complex multicomponent dust samples. Extinction spectra for the authentic dust samples were simulated from the derived sample mineralogy using published optical constant data for the individual mineral constituents and assuming an external mixture. Nonspherical particle shape effects were also included in the simulations and were shown to have a significant effect on the results. The results show that the position of the peak and the shape of the band of the IR characteristic features in the 800 to 1400 cm-1 spectral range are not well simulated by Mie theory. The resonance peaks are consistently shifted by more than +40 cm-1 relative to the experimental spectrum in the Mie simulation. Rayleigh model solutions for different particle shapes better predict the peak position and band shape of experimental spectra, even though the Rayleigh condition may not be strictly obeyed in these experiments.

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

    NASA Astrophysics Data System (ADS)

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

    2013-06-01

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

  11. Tunable 2.1-micron Ho lidar for simultaneous range-resolved measurements of atmospheric water vapor and aerosol backscatter profiles

    NASA Technical Reports Server (NTRS)

    Cha, Sungdo; Chan, Kin P.; Killinger, Dennis K.

    1991-01-01

    An eye-safe tunable differential-absorption lidar system has been developed for the range-resolved measurement of aerosol backscatter and water vapor in the atmosphere. The lidar uses a flash-lamp-pumped, Q-switched, 10-mJ solid-state Ho:YSGG laser that is continuously tunable over a 20/cm wavelength range near 2.084 microns. Both path-averaged and range-resolved measurements were performed with the Ho differential-absorption lidar system. Preliminary measurements have been made of the temporal variation of atmospheric aerosol backscatter and water-vapor profiles at ranges out to 1 km. These results indicate that the Ho lidar has the potential for the eye-safe remote sensing of atmospheric water vapor and backscatter profiles at longer ranges if suitably enhanced in laser power and laser linewidth.

  12. Retrieval of aerosol refractive index from extinction spectra with a damped harmonic-oscillator band model.

    PubMed

    Thomas, Gareth E; Bass, Stephen F; Grainger, Roy G; Lambert, Alyn

    2005-03-01

    A new method for the retrieval of the spectral refractive indices of micrometer-sized particles from infrared aerosol extinction spectra has been developed. With this method we use a classical damped harmonic-oscillator model of molecular absorption in conjunction with Mie scattering to model extinction spectra, which we then fit to the measurements using a numerical optimal estimation algorithm. The main advantage of this method over the more traditional Kramers-Kronig approach is that it allows the full complex refractive-index spectra, along with the parameters of the particle size distribution, to be retrieved from a single extinction spectrum. The retrieval scheme has been extensively characterized and has been found to provide refractive indices with a maximum uncertainty of approximately 10% (with a minimum of approximately 0.1%). Comparison of refractive indices calculated from measurements of a ternary solution of HNO3, H2SO4, and H2O with those published in J. Phys. Chem. A 104, 783 (2000) show similar differences as found by other authors.

  13. Characterization and source apportionment of aerosol light extinction with a coupled model of CMB-IMPROVE in Hangzhou, Yangtze River Delta of China

    NASA Astrophysics Data System (ADS)

    Wang, Jiao; Zhang, Yu-fen; Feng, Yin-chang; Zheng, Xian-jue; Jiao, Li; Hong, Sheng-mao; Shen, Jian-dong; Zhu, Tan; Ding, Jing; Zhang, Qi

    2016-09-01

    To investigate the characteristics and sources of aerosol light extinction in the Yangtze River Delta of China, a campaign was carried out in Hangzhou from December 2013 to November 2014. Hourly data for air pollutants including PM2.5, SO2, NO2, O3 and CO, and aerosol optical properties including aerosol scattering coefficient and aerosol absorbing coefficient was obtained in the environmental air quality automatic monitoring station. Meteorological parameters were measured synchronously in the automated meteorology monitoring station. Additionally, around seven sets of ambient PM2.5 samples per month were collected and analyzed during the campaign. The annual mean aerosol scattering coefficient, aerosol absorbing coefficient and aerosol single scattering albedo measured in this study was 514 ± 284 Mm- 1, 35 ± 20 Mm- 1 and 94% respectively. The aerosol extinction coefficient reconstructed using the modified IMPROVE (Interagency Monitoring of Protected Visual Environment) formula was compared to the measured extinction coefficient. Better correlations could be found between the measured and reconstructed extinction coefficient when RH was under 90%. A coupled model of CMB (chemical mass balance) and modified IMPROVE was used to apportion the sources of aerosol light extinction in Hangzhou. Vehicle exhaust, secondary nitrate and secondary sulfate were identified as the most significant sources for aerosol light extinction, accounted for 30.2%, 24.1% and 15.8% respectively.

  14. Behavior of zonal mean aerosol extinction ratio and its relationship with zonal mean temperature during the winter 1978-1979 stratospheric warming

    NASA Technical Reports Server (NTRS)

    Wang, P.-H.; Mccormick, M. P.

    1985-01-01

    The behavior of the zonal mean aerosol extinction ratio in the lower stratosphere near 75 deg N and its relationship with the zonal mean temperature during the January-February 1979 stratospheric sudden warming have been investigated based on the satellite sensor SAM II (Stratospheric Aerosol Measurement) and auxiliary meteorological measurements. The results indicate that distinct changes in the zonal mean aerosol extinction ratio occurred during this stratospheric sudden warming. It is also found that horizontal eddy transport due to planetary waves may have played a significant role in determining the distribution of the zonal mean aerosol extinction ratio.

  15. In situ vertical profiles of aerosol extinction, mass, and composition over the southeast United States during SENEX and SEAC4RS: observations of a modest aerosol enhancement aloft

    NASA Astrophysics Data System (ADS)

    Wagner, N. L.; Brock, C. A.; Angevine, W. M.; Beyersdorf, A.; Campuzano-Jost, P.; Day, D. A.; de Gouw, J. A.; Diskin, G. S.; Gordon, T. D.; Graus, M. G.; Huey, G.; Jimenez, J. L.; Lack, D. A.; Liao, J.; Liu, X.; Markovic, M. Z.; Middlebrook, A. M.; Mikoviny, T.; Peischl, J.; Perring, A. E.; Richardson, M. S.; Ryerson, T. B.; Schwarz, J. P.; Warneke, C.; Welti, A.; Wisthaler, A.; Ziemba, L. D.; Murphy, D. M.

    2015-02-01

    Vertical profiles of submicron aerosol over the southeastern United States (SEUS) during the summertime from in situ aircraft-based measurements were used to construct aggregate profiles of chemical, microphysical, and optical properties. Shallow cumulus convection was observed during many profiles. These conditions enhance vertical transport of trace gases and aerosol and create a cloudy transition layer on top of the sub-cloud mixed layer. The trace gas and aerosol concentrations in the transition layer were modeled as a mixture with contributions from the mixed layer below and the free troposphere above. The amount of vertical mixing, or entrainment of air from the free troposphere, was quantified using the observed mixing ratio of carbon monoxide (CO). Although the median aerosol mass, extinction, and volume decreased with altitude in the transition layer, they were ~10% larger than expected from vertical mixing alone. This enhancement was likely due to secondary aerosol formation in the transition layer. Although the transition layer enhancements of the particulate sulfate and organic aerosol (OA) were both similar in magnitude, only the enhancement of sulfate was statistically significant. The column integrated extinction, or aerosol optical depth (AOD), was calculated for each individual profile, and the transition layer enhancement of extinction typically contributed less than 10% to the total AOD. Our measurements and analysis were motivated by two recent studies that have hypothesized an enhanced layer of secondary organic aerosol (SOA) aloft to explain the summertime enhancement of AOD (2-3 times greater than winter) over the southeastern United States. In contrast to this hypothesis, the modest enhancement we observed in the transition layer was not dominated by OA and was not a large fraction of the summertime AOD.

  16. The CU Airborne MAX-DOAS instrument: vertical profiling of aerosol extinction and trace gases

    NASA Astrophysics Data System (ADS)

    Baidar, S.; Oetjen, H.; Coburn, S.; Dix, B.; Ortega, I.; Sinreich, R.; Volkamer, R.

    2013-03-01

    The University of Colorado Airborne Multi-Axis Differential Optical Absorption Spectroscopy (CU AMAX-DOAS) instrument uses solar stray light to detect and quantify multiple trace gases, including nitrogen dioxide (NO2), glyoxal (CHOCHO), formaldehyde (HCHO), water vapor (H2O), nitrous acid (HONO), iodine monoxide (IO), bromine monoxide (BrO), and oxygen dimers (O4) at multiple wavelengths (absorption bands at 360, 477, 577, 632 nm) simultaneously in the open atmosphere. The instrument is unique as it (1) features a motion compensation system that decouples the telescope field of view from aircraft movements in real time (<0.35° accuracy), and (2) includes measurements of solar stray light photons from nadir, zenith, and multiple elevation angles forward and below the plane by the same spectrometer/detector system. Sets of solar stray light spectra collected from nadir to zenith scans provide some vertical profile information within 2 km above and below the aircraft altitude, and the vertical column density (VCD) below the aircraft is measured in nadir view. Maximum information about vertical profiles is derived simultaneously for trace gas concentrations and aerosol extinction coefficients over similar spatial scales and with a vertical resolution of typically 250 m during aircraft ascent/descent. The instrument is described, and data from flights over California during the CalNex (California Research at the Nexus of Air Quality and Climate Change) and CARES (Carbonaceous Aerosols and Radiative Effects Study) air quality field campaigns is presented. Horizontal distributions of NO2 VCD (below the aircraft) maps are sampled with typically 1 km resolution, and show good agreement with two ground-based MAX-DOAS instruments (slope = 0.95 ± 0.09, R2 = 0.86). As a case study vertical profiles of NO2, CHOCHO, HCHO, and H2O concentrations and aerosol extinction coefficients, ɛ, at 477 nm calculated from O4 measurements from a low approach at Brackett airfield inside the

  17. Measurements of extinction by aerosol particles in the near-infrared using continuous wave cavity ring-down spectroscopy.

    PubMed

    Mellon, Daniel; King, Simon J; Kim, Jin; Reid, Jonathan P; Orr-Ewing, Andrew J

    2011-02-10

    Cavity ring-down spectroscopy using a fiber-coupled continuous wave distributed feedback laser at a wavelength of 1520 nm has been used to measure extinction of light by samples of nearly monodisperse aerosol particles <1 μm in diameter. A model is tested for the analysis of the sample extinction that is based on the Poisson statistics of the number of particles within the intracavity laser beam: variances of measured extinction are used to derive values of the scattering cross section for size-selected aerosol particles, without need for knowledge of the particle number density or sample length. Experimental parameters that influence the performance of the CRD system and the application and limitations of the statistical model are examined in detail. Determinations are reported of the scattering cross sections for polystyrene spheres (PSSs), sodium chloride, and ammonium sulfate, and, for particles greater than 500 nm in diameter, are shown to be in agreement with the corresponding values calculated using Mie theory or Discrete Dipole Approximation methods. For smaller particles, the experimentally derived values of the scattering cross section are larger than the theoretical predictions, and transmission of a small fraction of larger particles into the cavity is argued to be responsible for this discrepancy. The effects of cubic structure on the determination of optical extinction efficiencies of sodium chloride aerosol particles are examined. Values are reported for the real components of the refractive indices at 1520 nm of PSS, sodium chloride, and ammonium sulfate aerosol particles.

  18. Scanning Backscatter Lidar Observations for Characterizing 4-D Cloud and Aerosol Fields to Improve Radiative Transfer Parameterizations

    NASA Technical Reports Server (NTRS)

    Schwemmer, Geary K.; Miller, David O.

    2005-01-01

    Clouds have a powerful influence on atmospheric radiative transfer and hence are crucial to understanding and interpreting the exchange of radiation between the Earth's surface, the atmosphere, and space. Because clouds are highly variable in space, time and physical makeup, it is important to be able to observe them in three dimensions (3-D) with sufficient resolution that the data can be used to generate and validate parameterizations of cloud fields at the resolution scale of global climate models (GCMs). Simulation of photon transport in three dimensionally inhomogeneous cloud fields show that spatial inhomogeneities tend to decrease cloud reflection and absorption and increase direct and diffuse transmission, Therefore it is an important task to characterize cloud spatial structures in three dimensions on the scale of GCM grid elements. In order to validate cloud parameterizations that represent the ensemble, or mean and variance of cloud properties within a GCM grid element, measurements of the parameters must be obtained on a much finer scale so that the statistics on those measurements are truly representative. High spatial sampling resolution is required, on the order of 1 km or less. Since the radiation fields respond almost instantaneously to changes in the cloud field, and clouds changes occur on scales of seconds and less when viewed on scales of approximately 100m, the temporal resolution of cloud properties should be measured and characterized on second time scales. GCM time steps are typically on the order of an hour, but in order to obtain sufficient statistical representations of cloud properties in the parameterizations that are used as model inputs, averaged values of cloud properties should be calculated on time scales on the order of 10-100 s. The Holographic Airborne Rotating Lidar Instrument Experiment (HARLIE) provides exceptional temporal (100 ms) and spatial (30 m) resolution measurements of aerosol and cloud backscatter in three

  19. On the accuracy of stratospheric aerosol extinction derived from in situ size distribution measurements and surface area density derived from remote SAGE II and HALOE extinction measurements

    SciTech Connect

    Kovilakam, Mahesh; Deshler, Terry

    2015-08-26

    In situ stratospheric aerosol measurements, from University of Wyoming optical particle counters (OPCs), are compared with Stratospheric Aerosol Gas Experiment (SAGE) II (versions 6.2 and 7.0) and Halogen Occultation Experiment (HALOE) satellite measurements to investigate differences between SAGE II/HALOE-measured extinction and derived surface area and OPC-derived extinction and surface area. Coincident OPC and SAGE II measurements are compared for a volcanic (1991-1996) and nonvolcanic (1997 2005) period. OPC calculated extinctions agree with SAGE II measurements, within instrumental uncertainty, during the volcanic period, but have been a factor of 2 low during the nonvolcanic period. Three systematic errors associated with the OPC measurements, anisokineticity, inlet particle evaporation, and counting efficiency, were investigated. An overestimation of the OPC counting efficiency is found to be the major source of systematic error. With this correction OPC calculated extinction increases by 15 30% (30 50%) for the volcanic (nonvolcanic) measurements. These changes significantly improve the comparison with SAGE II and HALOE extinctions in the nonvolcanic cases but slightly degrade the agreement in the volcanic period. These corrections have impacts on OPC-derived surface area density, exacerbating the poor agreement between OPC and SAGE II (version 6.2) surface areas. This disparity is reconciled with SAGE II version 7.0 surface areas. For both the volcanic and nonvolcanic cases these changes in OPC counting efficiency and in the operational SAGE II surface area algorithm leave the derived surface areas from both platforms in significantly better agreement and within the 40% precision of the OPC moment calculations.

  20. On the accuracy of stratospheric aerosol extinction derived from in situ size distribution measurements and surface area density derived from remote SAGE II and HALOE extinction measurements

    DOE PAGES

    Kovilakam, Mahesh; Deshler, Terry

    2015-08-26

    In situ stratospheric aerosol measurements, from University of Wyoming optical particle counters (OPCs), are compared with Stratospheric Aerosol Gas Experiment (SAGE) II (versions 6.2 and 7.0) and Halogen Occultation Experiment (HALOE) satellite measurements to investigate differences between SAGE II/HALOE-measured extinction and derived surface area and OPC-derived extinction and surface area. Coincident OPC and SAGE II measurements are compared for a volcanic (1991-1996) and nonvolcanic (1997 2005) period. OPC calculated extinctions agree with SAGE II measurements, within instrumental uncertainty, during the volcanic period, but have been a factor of 2 low during the nonvolcanic period. Three systematic errors associated with themore » OPC measurements, anisokineticity, inlet particle evaporation, and counting efficiency, were investigated. An overestimation of the OPC counting efficiency is found to be the major source of systematic error. With this correction OPC calculated extinction increases by 15 30% (30 50%) for the volcanic (nonvolcanic) measurements. These changes significantly improve the comparison with SAGE II and HALOE extinctions in the nonvolcanic cases but slightly degrade the agreement in the volcanic period. These corrections have impacts on OPC-derived surface area density, exacerbating the poor agreement between OPC and SAGE II (version 6.2) surface areas. This disparity is reconciled with SAGE II version 7.0 surface areas. For both the volcanic and nonvolcanic cases these changes in OPC counting efficiency and in the operational SAGE II surface area algorithm leave the derived surface areas from both platforms in significantly better agreement and within the 40% precision of the OPC moment calculations.« less

  1. Radiative and thermodynamic responses to aerosol extinction profiles during the pre-monsoon month over South Asia

    SciTech Connect

    Feng, Y.; Kotamarthi, V. R.; Coulter, R.; Zhao, C.; Cadeddu, M.

    2016-01-01

    Aerosol radiative effects and thermodynamic responses over South Asia are examined with the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) for March 2012. Model results of aerosol optical depths (AODs) and extinction profiles are analyzed and compared to satellite retrievals and two ground-based lidars located in northern India. The WRF-Chem model is found to heavily underestimate the AOD during the simulated pre-monsoon month and about 83 % of the model's low bias is due to aerosol extinctions below ~2 km. Doubling the calculated aerosol extinctions below 850 hPa generates much better agreement with the observed AOD and extinction profiles averaged over South Asia. To separate the effect of absorption and scattering properties, two runs were conducted: in one run (Case I), the calculated scattering and absorption coefficients were increased proportionally, while in the second run (Case II) only the calculated aerosol scattering coefficient was increased. With the same AOD and extinction profiles, the two runs produce significantly different radiative effects over land and oceans. On the regional mean basis, Case I generates 48 % more heating in the atmosphere and 21 % more dimming at the surface than Case II. Case I also produces stronger cooling responses over the land from the longwave radiation adjustment and boundary layer mixing. These rapid adjustments offset the stronger radiative heating in Case I and lead to an overall lower-troposphere cooling up to -0.7 K day−1, which is smaller than that in Case II. Over the ocean, direct radiative effects dominate the heating rate changes in the lower atmosphere lacking such surface and lower atmosphere adjustments due to fixed sea surface temperature, and the strongest atmospheric warming is obtained in Case I. Consequently, atmospheric dynamics (boundary layer heights and meridional circulation) and thermodynamic processes (water vapor and cloudiness) are shown to

  2. Radiative and thermodynamic responses to aerosol extinction profiles during the pre-monsoon month over South Asia

    DOE PAGES

    Feng, Y.; Kotamarthi, V. R.; Coulter, R.; ...

    2015-06-19

    Aerosol radiative effects and thermodynamic responses over South Asia are examined with a version of the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) for March 2012. Model results of Aerosol Optical Depth (AOD) and extinction profiles are analyzed and compared to satellite retrievals and two ground-based lidars located in the northern India. The WRF-Chem model is found to underestimate the AOD during the simulated pre-monsoon month and about 83 % of the model low-bias is due to aerosol extinctions below ~2 km. Doubling the calculated aerosol extinctions below 850 hPa generates much better agreement with the observed AODmore » and extinction profiles averaged over South Asia. To separate the effect of absorption and scattering properties, two runs were conducted: in one run (Case I), the calculated scattering and absorption coefficients were increased proportionally, while in the second run (Case II) only the calculated aerosol scattering coefficient was increased. With the same AOD and extinction profiles, the two runs produce significantly different radiative effects over land and oceans. On the regional mean basis, Case I generates 48 % more heating in the atmosphere and 21 % more dimming at the surface than Case II. Case I also produces stronger cooling responses over the land from the longwave radiation adjustment and boundary layer mixing. These rapid adjustments offset the stronger radiative heating in Case I and lead to an overall lower-troposphere cooling up to -0.7 K day−1, which is smaller than that in Case II. Over the ocean, direct radiative effects dominate the heating rate changes in the lower atmosphere lacking such surface and lower atmosphere adjustments due to fixed sea surface temperature, and the strongest atmospheric warming is obtained in Case I. Consequently, atmospheric dynamics (boundary layer heights and meridional circulation) and thermodynamic processes (water vapor and cloudiness) are shown to respond

  3. Radiative and thermodynamic responses to aerosol extinction profiles during the pre-monsoon month over South Asia

    SciTech Connect

    Feng, Y.; Kotamarthi, V. R.; Coulter, R.; Zhao, C.; Cadeddu, M.

    2015-06-19

    Aerosol radiative effects and thermodynamic responses over South Asia are examined with a version of the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) for March 2012. Model results of Aerosol Optical Depth (AOD) and extinction profiles are analyzed and compared to satellite retrievals and two ground-based lidars located in the northern India. The WRF-Chem model is found to underestimate the AOD during the simulated pre-monsoon month and about 83 % of the model low-bias is due to aerosol extinctions below ~2 km. Doubling the calculated aerosol extinctions below 850 hPa generates much better agreement with the observed AOD and extinction profiles averaged over South Asia. To separate the effect of absorption and scattering properties, two runs were conducted: in one run (Case I), the calculated scattering and absorption coefficients were increased proportionally, while in the second run (Case II) only the calculated aerosol scattering coefficient was increased. With the same AOD and extinction profiles, the two runs produce significantly different radiative effects over land and oceans. On the regional mean basis, Case I generates 48 % more heating in the atmosphere and 21 % more dimming at the surface than Case II. Case I also produces stronger cooling responses over the land from the longwave radiation adjustment and boundary layer mixing. These rapid adjustments offset the stronger radiative heating in Case I and lead to an overall lower-troposphere cooling up to -0.7 K day−1, which is smaller than that in Case II. Over the ocean, direct radiative effects dominate the heating rate changes in the lower atmosphere lacking such surface and lower atmosphere adjustments due to fixed sea surface temperature, and the strongest atmospheric warming is obtained in Case I. Consequently, atmospheric dynamics (boundary layer heights and meridional circulation) and thermodynamic processes (water vapor and cloudiness) are shown to respond

  4. Radiative and thermodynamic responses to aerosol extinction profiles during the pre-monsoon month over South Asia

    DOE PAGES

    Feng, Y.; Kotamarthi, V. R.; Coulter, R.; ...

    2016-01-18

    Aerosol radiative effects and thermodynamic responses over South Asia are examined with the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) for March 2012. Model results of aerosol optical depths (AODs) and extinction profiles are analyzed and compared to satellite retrievals and two ground-based lidars located in northern India. The WRF-Chem model is found to heavily underestimate the AOD during the simulated pre-monsoon month and about 83 % of the model's low bias is due to aerosol extinctions below  ∼  2 km. Doubling the calculated aerosol extinctions below 850 hPa generates much better agreement with the observed AOD and extinction profiles averaged over Southmore » Asia. To separate the effect of absorption and scattering properties, two runs were conducted: in one run (Case I), the calculated scattering and absorption coefficients were increased proportionally, while in the second run (Case II) only the calculated aerosol scattering coefficient was increased. With the same AOD and extinction profiles, the two runs produce significantly different radiative effects over land and oceans. On the regional mean basis, Case I generates 48 % more heating in the atmosphere and 21 % more dimming at the surface than Case II. Case I also produces stronger cooling responses over the land from the longwave radiation adjustment and boundary layer mixing. These rapid adjustments offset the stronger radiative heating in Case I and lead to an overall lower-troposphere cooling up to −0.7 K day−1, which is smaller than that in Case II. Over the ocean, direct radiative effects dominate the heating rate changes in the lower atmosphere lacking such surface and lower atmosphere adjustments due to fixed sea surface temperature, and the strongest atmospheric warming is obtained in Case I. Consequently, atmospheric dynamics (boundary layer heights and meridional circulation) and thermodynamic processes (water vapor and

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

    NASA Technical Reports Server (NTRS)

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

    2002-01-01

    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.

  6. Atmospheric aerosols: Their Optical Properties and Effects (supplement)

    NASA Technical Reports Server (NTRS)

    1976-01-01

    A digest of technical papers is presented. Topics include aerosol size distribution from spectral attenuation with scattering measurements; comparison of extinction and backscattering coefficients for measured and analytic stratospheric aerosol size distributions; using hybrid methods to solve problems in radiative transfer and in multiple scattering; blue moon phenomena; absorption refractive index of aerosols in the Denver pollution cloud; a two dimensional stratospheric model of the dispersion of aerosols from the Fuego volcanic eruption; the variation of the aerosol volume to light scattering coefficient; spectrophone in situ measurements of the absorption of visible light by aerosols; a reassessment of the Krakatoa volcanic turbidity, and multiple scattering in the sky radiance.

  7. AerGOM, an improved algorithm for stratospheric aerosol extinction retrieval from GOMOS observations - Part 2: Intercomparisons

    NASA Astrophysics Data System (ADS)

    Étienne Robert, Charles; Bingen, Christine; Vanhellemont, Filip; Mateshvili, Nina; Dekemper, Emmanuel; Tétard, Cédric; Fussen, Didier; Bourassa, Adam; Zehner, Claus

    2016-09-01

    AerGOM is a retrieval algorithm developed for the GOMOS instrument onboard Envisat as an alternative to the operational retrieval (IPF). AerGOM enhances the quality of the stratospheric aerosol extinction retrieval due to the extension of the spectral range used, refines the aerosol spectral parameterization, the simultaneous inversion of all atmospheric species as well as an improvement of the Rayleigh scattering correction. The retrieval algorithm allows for a good characterization of the stratospheric aerosol extinction for a wide range of wavelengths.In this work, we present the results of stratospheric aerosol extinction comparisons between AerGOM and various spaceborne instruments (SAGE II, SAGE III, POAM III, ACE-MAESTRO and OSIRIS) for different wavelengths. The aerosol extinction intercomparisons for λ < 700 nm and above 20 km show agreements with SAGE II version 7 and SAGE III version 4.0 within ±15 % and ±45 %, respectively. There is a strong positive bias below 20 km at λ < 700 nm, which suggests that cirrus clouds at these altitudes have a large impact on the extinction values. Comparisons performed with GOMOS IPF v6.01 alongside AerGOM show that at short wavelengths and altitudes below 20 km, IPF retrievals are more accurate when evaluated against SAGE II and SAGE III but are much less precise than AerGOM. A modified aerosol spectral parameterization can improve AerGOM in this spectral and altitude range and leads to results that have an accuracy similar to IPF retrievals. Comparisons of AerGOM aerosol extinction coefficients with OSIRIS and SAGE III measurements at wavelengths larger than 700 nm show a very large negative bias at altitudes above 25 km. Therefore, the use of AerGOM aerosol extinction data is not recommended for λ > 700 nm.Due to the unique observational technique of GOMOS, some of the results appear to be dependent on the star occultation parameters such as star apparent temperature and magnitude, solar zenith angle

  8. In situ vertical profiles of aerosol extinction, mass, and composition over the southeast United States during SENEX and SEAC4RS: observations of a modest aerosol enhancement aloft

    NASA Astrophysics Data System (ADS)

    Wagner, N. L.; Brock, C. A.; Angevine, W. M.; Beyersdorf, A.; Campuzano-Jost, P.; Day, D.; de Gouw, J. A.; Diskin, G. S.; Gordon, T. D.; Graus, M. G.; Holloway, J. S.; Huey, G.; Jimenez, J. L.; Lack, D. A.; Liao, J.; Liu, X.; Markovic, M. Z.; Middlebrook, A. M.; Mikoviny, T.; Peischl, J.; Perring, A. E.; Richardson, M. S.; Ryerson, T. B.; Schwarz, J. P.; Warneke, C.; Welti, A.; Wisthaler, A.; Ziemba, L. D.; Murphy, D. M.

    2015-06-01

    Vertical profiles of submicron aerosol from in situ aircraft-based measurements were used to construct aggregate profiles of chemical, microphysical, and optical properties. These vertical profiles were collected over the southeastern United States (SEUS) during the summer of 2013 as part of two separate field studies: the Southeast Nexus (SENEX) study and the Study of Emissions and Atmospheric Composition, Clouds, and Climate Coupling by Regional Surveys (SEAC4RS). Shallow cumulus convection was observed during many profiles. These conditions enhance vertical transport of trace gases and aerosol and create a cloudy transition layer on top of the sub-cloud mixed layer. The trace gas and aerosol concentrations in the transition layer were modeled as a mixture with contributions from the mixed layer below and the free troposphere above. The amount of vertical mixing, or entrainment of air from the free troposphere, was quantified using the observed mixing ratio of carbon monoxide (CO). Although the median aerosol mass, extinction, and volume decreased with altitude in the transition layer, they were ~10 % larger than expected from vertical mixing alone. This enhancement was likely due to secondary aerosol formation in the transition layer. Although the transition layer enhancements of the particulate sulfate and organic aerosol (OA) were both similar in magnitude, only the enhancement of sulfate was statistically significant. The column integrated extinction, or aerosol optical depth (AOD), was calculated for each individual profile, and the transition layer enhancement of extinction typically contributed less than 10 % to the total AOD. Our measurements and analysis were motivated by two recent studies that have hypothesized an enhanced layer of secondary aerosol aloft to explain the summertime enhancement of AOD (2-3 times greater than winter) over the southeastern United States. The first study attributes the layer aloft to secondary organic aerosol (SOA) while

  9. Inversion of solar extinction data from the Apollo-Soyuz Test Project Stratospheric Aerosol Measurement (ASTP/SAM) experiment

    NASA Technical Reports Server (NTRS)

    Pepin, T. J.

    1977-01-01

    The inversion methods are reported that have been used to determine the vertical profile of the extinction coefficient due to the stratospheric aerosols from data measured during the ASTP/SAM solar occultation experiment. Inversion methods include the onion skin peel technique and methods of solving the Fredholm equation for the problem subject to smoothing constraints. The latter of these approaches involves a double inversion scheme. Comparisons are made between the inverted results from the SAM experiment and near simultaneous measurements made by lidar and balloon born dustsonde. The results are used to demonstrate the assumptions required to perform the inversions for aerosols.

  10. Aerosol backscatter measurements at 10.6 microns with airborne and ground-based CO2 Doppler lidars over the Colorado High Plains. I - Lidar intercomparison

    NASA Technical Reports Server (NTRS)

    Bowdle, David A.; Rothermel, Jeffry; Vaughan, J. Michael; Brown, Derek W.; Post, Madison J.

    1991-01-01

    An airborne continuous-wave (CW) focused CO2 Doppler lidar and a ground-based pulsed CO2 Doppler lidar were to obtain seven pairs of comparative measurements of tropospheric aerosol backscatter profiles at 10.6-micron wavelength, near Denver, Colorado, during a 20-day period in July 1982. In regions of uniform backscatter, the two lidars show good agreement, with differences usually less than about 50 percent near 8-km altitude and less than a factor of 2 or 3 elsewhere but with the pulsed lidar often lower than the CW lidar. Near sharp backscatter gradients, the two lidars show poorer agreement, with the pulsed lidar usually higher than the CW lidar. Most discrepancies arise from a combination of atmospheric factors and instrument factors, particularly small-scale areal and temporal backscatter heterogeneity above the planetary boundary layer, unusual large-scale vertical backscatter structure in the upper troposphere and lower stratosphere, and differences in the spatial resolution, detection threshold, and noise estimation for the two lidars.

  11. Evaluating Nighttime CALIOP 0.532 micron Aerosol Optical Depth and Extinction Coefficient Retrievals

    NASA Technical Reports Server (NTRS)

    Campbell, J. R.; Tackett, J. L.; Reid, J. S.; Zhang, J.; Curtis, C. A.; Hyer, E. J.; Sessions, W. R.; Westphal, D. L.; Prospero, J. M.; Welton, E. J.; Omar, A. H.; Vaughan, M. A.; Winker, D. M.

    2012-01-01

    NASA Cloud Aerosol Lidar with Orthogonal Polarization (CALIOP) Version 3.01 5-km nighttime 0.532 micron aerosol optical depth (AOD) datasets from 2007 are screened, averaged and evaluated at 1 deg X 1 deg resolution versus corresponding/co-incident 0.550 micron AOD derived using the US Navy Aerosol Analysis and Prediction System (NAAPS), featuring two-dimensional variational assimilation of quality-assured NASA Moderate Resolution Imaging Spectroradiometer (MODIS) and Multi-angle Imaging Spectroradiometer (MISR) AOD. In the absence of sunlight, since passive radiometric AOD retrievals rely overwhelmingly on scattered radiances, the model represents one of the few practical global estimates available from which to attempt such a validation. Daytime comparisons, though, provide useful context. Regional-mean CALIOP vertical profiles of night/day 0.532 micron extinction coefficient are compared with 0.523/0.532 micron ground-based lidar measurements to investigate representativeness and diurnal variability. In this analysis, mean nighttime CALIOP AOD are mostly lower than daytime (0.121 vs. 0.126 for all aggregated data points, and 0.099 vs. 0.102 when averaged globally per normalised 1 deg. X 1 deg. bin), though the relationship is reversed over land and coastal regions when the data are averaged per normalised bin (0.134/0.108 vs. 0140/0.112, respectively). Offsets assessed within single bins alone approach +/- 20 %. CALIOP AOD, both day and night, are higher than NAAPS over land (0.137 vs. 0.124) and equal over water (0.082 vs. 0.083) when averaged globally per normalised bin. However, for all data points inclusive, NAAPS exceeds CALIOP over land, coast and ocean, both day and night. Again, differences assessed within single bins approach 50% in extreme cases. Correlation between CALIOP and NAAPS AOD is comparable during both day and night. Higher correlation is found nearest the equator, both as a function of sample size and relative signal magnitudes inherent at

  12. GLOBE backscatter - Climatologies and mission results. [Global Backscatter Experiment

    NASA Technical Reports Server (NTRS)

    Menzies, Robert T.; Post, Madison J.

    1991-01-01

    The Global Backscatter Experiment (GLOBE) goals require intensive study of the global climatology of atmospheric aerosol backscatter at IR wavelengths. Airborne and ground-based lidars have been developed to measure atmospheric backscatter profiles at CO2 laser wavelengths. Descriptions of the calibration techniques and selected measurement results are presented.

  13. Vertical distribution of ambient aerosol extinctive properties during haze and haze-free periods based on the Micro-Pulse Lidar observation in Shanghai.

    PubMed

    Liu, Qiong; He, Qianshan; Fang, Sihua; Guang, Ying; Ma, Chengyu; Chen, Yonghang; Kang, Yanming; Pan, Hu; Zhang, Hua; Yao, Yifeng

    2017-01-01

    Ambient aerosols make a significant contribution to the environment and climate through their optical properties. In this study, the aerosol extinction coefficient and Aerosol optical depth (AOD) retrieved using the Fernald Method from the ground-based Micro-Pulse Lidar (MPL) were used to investigate the characteristics of aerosols during haze and haze-free periods in Shanghai. There were 216 haze days including 145 dry haze days, 39 damp haze days and 32days of both dry and damp haze in Shanghai from March 2009 to February 2010. During the haze periods, aerosols were concentrated mainly below 600m resulting in the most severe pollution layer in Shanghai. In contrast to the aerosol optical properties during haze-free periods, aerosol extinction coefficients and AOD were larger in the lower altitude (below 1km) during haze periods. The lowest 1km contributed 53-72% of the Aerosol optical depth (AOD) below 6km for the haze periods and <41% of that for the haze-free periods except summer. According to the analysis of influencing factors, although atmospheric convection was strong in summer which led to reduce the extinction, the highest occurrence of haze with relatively low aerosol extinction most of time was in summer, which resulted from the factors such as higher relative humidity, temperature and more solar radiation causing hygroscopic growth of particles and formation of secondary aerosols; in spring and autumn, there was less haze occurrences because the boundary layer was relatively higher, which allowed pollutants to diffuse more easily, but spring was the second most frequency season of haze due to frequent dust transport from the north; in winter high concentrations of particles and low boundary layer height were not beneficial to the diffusion of pollutants near the surface and caused haze occurrence rather high with high aerosol extinction.

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

    NASA Technical Reports Server (NTRS)

    Whiteman, David N.

    2003-01-01

    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.

  15. Optical properties of urban aerosols, aircraft emissions, and heavy-duty diesel trucks using aerosol light extinction measurements by an Aerodyne Cavity Attenuated Phase Shift Particle Extinction Monitor (CAPS PMex)

    NASA Astrophysics Data System (ADS)

    Freedman, A.; Massoli, P.; Wood, E. C.; Allan, J. D.; Fortner, E.; Yu, Z.; Herndon, S. C.; Miake-Lye, R. C.; Onasch, T. B.

    2010-12-01

    We present results of optical property characterization of ambient particulate during several field deployments where measurements of aerosol light extinction (σep) are obtained using an Aerodyne Cavity Attenuated Phase Shift Particle Extinction Monitor (CAPS PMex). The CAPS PMex is able to provide extinction measurements with 3-σ detection limit of 3 Mm-1 for 1s integration time. The CAPS PMex (630 nm) is integrated in the Aerodyne Research, Inc. (ARI) mobile laboratory where a co-located Multi Angle Absorption Photometer (MAAP) provides particle light absorption coefficient at 632 nm. The combination of the CAPS with the MAAP data allows estimating the single scattering albedo (ω) of the ambient aerosol particles. The ARI mobile laboratory was deployed in winter 2010 at the Chicago O’Hare International Airport to measure gas phase and particulate emissions from different aircraft engines, and during summer 2010 in Oakland, CA, to characterize vehicular gaseous and particulate emissions (mainly exhaust from heavy-duty diesel trucks) from the Caldecott Tunnel. We provide estimates of black carbon emission factors from individual aircraft engines and diesel trucks, in addition to characterizing the optical properties of these ambient samples studying fleet-average emissions for both light-duty passenger vehicles and heavy-duty diesel trucks. Two CAPS PMex instruments (measuring σep at 630 and 532 nm) were also deployed during the CalNex 2010 study (May 14 - June 16) at the CalTech ground site in Pasadena, CA. During the same time, a photo-acoustic spectrometer (PAS, DMT) and an aethalometer instrument (Magee Sci.) measured particle light absorption of submicron aerosol particles from the same sample line as the CAPS PMex monitors. We combine these data to provide multi-wavelength ω trends for the one-month campaign. Our results show the high potential of the CAPS as light weight, compact instrument to perform precise and accurate σep measurements of

  16. Improved identification of transition metals in airborne aerosols by SEM-EDX combined backscattered and secondary electron microanalysis.

    PubMed

    Pietrodangelo, A; Pareti, S; Perrino, C

    2014-03-01

    The SEM EDX backscattered electron (BSE) atomic number contrast has been largely used in this work, in combination with conventional secondary electron microanalysis, to investigate the presence of metal particles in airborne particulate collected at three sites (industrial, residential, and rural background) in the Po Valley (Italy). Individual particle x-ray microanalysis was used for this aim. In many cases, the presence of metal particles was not evident by secondary electron imaging and it was instead revealed by BSE detection. Metal particles were observed either as isolated (not clustered to other particles), or gathered together (homogeneous clusters). In addition, the BSE microanalysis put on evidence two main types of association of metals to other particulate components: heterogeneous clusters and metals embedded or enclosed in other materials. In this study, the first association (heterogeneous clusters) was observed mostly between Fe-bearing metallic particles and soot aggregates (or other carbonaceous particles) and it was found in the particulate matter (PM) of all studied sites. The second association, conversely, seems to be characterized by more selective relationships between composition/size of metal particles and type of other particulate components. These associations could be evidenced only when using the BSE Z-contrast and mainly concern three cases: (1) unusual silicate-carbonate mixed aggregates were observed at the industrial site only. In these aggregates, embedded Mn, Cr, Co, Bi, W, and Zr fine particles were selectively observed. (2) Ni and V rich ultrafine particles were only observed as embedded particles in the surface structure of carbon cenospheres. (3) Pb or Pb-Zn bearing fine and ultrafine particles were largely detected only in oxygenated organic aerosols in the ultrafine PM.

  17. Investigating vertical distributions of ozone and of the aerosol extinction coefficient in the middle atmosphere with the MKS-M and SFN-4 instruments on board Salyut-7

    NASA Astrophysics Data System (ADS)

    Badaev, V. V.; Grechko, G. M.; Elanskii, N. F.; Kan, V.; Plotkin, M. E.

    1989-04-01

    The technical characteristics of the multichannel spectrometer (MKS-M) system combined with a camera containing a spectrophotography attachment (SFN-4) are discussed together with results obtained by this system on distributions of ozone and aerosol in the middle atmosphere. It is demonstrated that this system is capable of retrieving the fine structure of vertical ozone and aerosol extinction distributions in the lower stratosphere. Results show that, in the ozonosphere, the contents of ozone and of aerosol exhibit a negative correlation.

  18. 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)

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

    2002-01-01

    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.

  19. Airborne High Spectral Resolution Lidar Measurements of Atmospheric Aerosols

    NASA Astrophysics Data System (ADS)

    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

    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

  20. AerGOM, an improved algorithm for stratospheric aerosol extinction retrieval from GOMOS observations - Part 1: Algorithm description

    NASA Astrophysics Data System (ADS)

    Vanhellemont, Filip; Mateshvili, Nina; Blanot, Laurent; Étienne Robert, Charles; Bingen, Christine; Sofieva, Viktoria; Dalaudier, Francis; Tétard, Cédric; Fussen, Didier; Dekemper, Emmanuel; Kyrölä, Erkki; Laine, Marko; Tamminen, Johanna; Zehner, Claus

    2016-09-01

    The GOMOS instrument on Envisat has successfully demonstrated that a UV-Vis-NIR spaceborne stellar occultation instrument is capable of delivering quality data on the gaseous and particulate composition of Earth's atmosphere. Still, some problems related to data inversion remained to be examined. In the past, it was found that the aerosol extinction profile retrievals in the upper troposphere and stratosphere are of good quality at a reference wavelength of 500 nm but suffer from anomalous, retrieval-related perturbations at other wavelengths. Identification of algorithmic problems and subsequent improvement was therefore necessary. This work has been carried out; the resulting AerGOM Level 2 retrieval algorithm together with the first data version AerGOMv1.0 forms the subject of this paper. The AerGOM algorithm differs from the standard GOMOS IPF processor in a number of important ways: more accurate physical laws have been implemented, all retrieval-related covariances are taken into account, and the aerosol extinction spectral model is strongly improved. Retrieval examples demonstrate that the previously observed profile perturbations have disappeared, and the obtained extinction spectra look in general more consistent. We present a detailed validation study in a companion paper; here, to give a first idea of the data quality, a worst-case comparison at 386 nm shows SAGE II-AerGOM correlation coefficients that are up to 1 order of magnitude larger than the ones obtained with the GOMOS IPFv6.01 data set.

  1. In situ measurement of the infrared absorption and extinction of chemical and biologically derived aerosols using flow-through photoacoustics

    NASA Astrophysics Data System (ADS)

    Gurton, Kristan P.; Dahmani, Rachid; Ligon, David; Bronk, Burt V.

    2005-07-01

    In an effort to establish a more reliable set of optical cross sections for a variety of chemical and biological aerosol simulants, we have developed a flow-through photoacoustic system that is capable of measuring absolute, mass-normalized extinction and absorption cross sections. By employing a flow-through design we avoid issues associated with closed aerosol photoacoustic systems and improve sensitivity. Although the results shown here were obtained for the tunable CO2 laser waveband region, i.e., 9.20-10.80 μm, application to other wavelengths is easily achievable. The aerosols considered are categorized as biological, chemical, and inorganic in origin, i.e., Bacillus atrophaeus endospores, dimethicone silicone oil (SF-96 grade 50), and kaolin clay powder (alumina and silicate), respectively. Results compare well with spectral extinction measured previously by Fourier-transform infrared spectroscopy. Comparisons with Mie theory calculations based on previously published complex indices of refraction and measured size distributions are also presented.

  2. UV/Visible Aerosol Extinction Measurements performed by GOMOS onboard ENVISAT: results for the period August 2002 to March 2005.

    NASA Astrophysics Data System (ADS)

    Vanhellemont, F.; Fussen, D.; Dodion, J.; Bingen, C.; Mateshvili, N.; Gomos Team

    Launched in March 2002 the GOMOS Global Ozone Monitoring by Occultation of Stars instrument onboard the European Envisat satellite has already provided a wealth of information on the geographical and temporal distribution of several atmospheric species Vertical profiles for these species are numerically retrieved from measurements of starlight that is transmitted through the atmosphere at different tangent altitudes The actual spectrum at each tangent altitude is measured within the UV Visible wavelength range Typically within the useful range from 248 nm to 690 nm gas concentration profiles for O 3 NO 2 H 2 O neutral air and aerosol extinction profiles can be retrieved Although stars are relatively weak light sources the advantage of the star occultation lies in the fact that useful stars are available at all times during orbit As a consequence GOMOS has measured more than 300 000 occultations in the considered period from August 2002 to March 2005 In this work we present results for the aerosol extinction retrievals Using selection criteria for different occultation properties such as the star magnitude and the illumination conditions a subset of reliable occultations were picked Subsequently a spatial and temporal binning was performed and data were averaged The resulting climatology provides a good view on the spatial distribution and temporal evolution of aerosols in the stratosphere Special attention is given to the presence of PSCs in the Antarctic polar vortex and equatorial cirrus clouds First results on particle sizes

  3. Four-year long-path monitoring of ambient aerosol extinction at a central European urban site: dependence on relative humidity

    NASA Astrophysics Data System (ADS)

    Skupin, A.; Ansmann, A.; Engelmann, R.; Seifert, P.; Müller, T.

    2016-02-01

    The ambient aerosol particle extinction coefficient is measured with the Spectral Aerosol Extinction Monitoring System (SÆMS) along a 2.84 km horizontal path at 30-50 m height above ground in the urban environment of Leipzig (51.3° N, 12.4° E), Germany, since 2009. The dependence of the particle extinction coefficient (wavelength range from 300 to 1000 nm) on relative humidity up to almost 100 % was investigated. The main results are presented. For the wavelength of 550 nm, the mean extinction enhancement factor was found to be 1.75 ± 0.4 for an increase of relative humidity from 40 to 80 %. The respective 4-year mean extinction enhancement factor is 2.8 ± 0.6 for a relative-humidity increase from 40 to 95 %. A parameterization of the dependency of the urban particle extinction coefficient on relative humidity is presented. A mean hygroscopic exponent of 0.46 for the 2009-2012 period was determined. Based on a backward trajectory cluster analysis, the dependence of several aerosol optical properties for eight air flow regimes was investigated. Large differences were not found, indicating that local pollution sources widely control the aerosol conditions over the urban site. The comparison of the SÆMS extinction coefficient statistics with respective statistics from ambient AERONET sun photometer observations yields good agreement. Also, time series of the particle extinction coefficient computed from in situ-measured dry particle size distributions and humidity-corrected SÆMS extinction values (for 40 % relative humidity) were found in good overall consistency, which verifies the applicability of the developed humidity parameterization scheme. The analysis of the spectral dependence of particle extinction (Ångström exponent) revealed an increase of the 390-881 nm Ångström exponent from, on average, 0.3 (at 30 % relative humidity) to 1.3 (at 95 % relative humidity) for the 4-year period.

  4. Cloud-Aerosol Interactions: Retrieving Aerosol Ångström Exponents from Calipso Measurements of Opaque Water Clouds

    NASA Astrophysics Data System (ADS)

    Vaughan, Mark; Liu, Zhaoyan; Hu, Yong-Xiang; Powell, Kathleen; Omar, Ali; Rodier, Sharon; Hunt, William; Kar, Jayanta; Tackett, Jason; Getzewich, Brian; Lee, Kam-Pui

    2016-06-01

    Backscatter and extinction from water clouds are well-understood, both theoretically and experimentally, and thus changes to the expected measurement of layer-integrated attenuated backscatter can be used to infer the optical properties of overlying layers. In this paper we offer a first look at a new retrieval technique that uses CALIPSO measurements of opaque water clouds to derive optical depths and Ångström exponents for overlying aerosol layers.

  5. Verification and application of the extended spectral deconvolution algorithm (SDA+) methodology to estimate aerosol fine and coarse mode extinction coefficients in the marine boundary layer

    NASA Astrophysics Data System (ADS)

    Kaku, K. C.; Reid, J. S.; O'Neill, N. T.; Quinn, P. K.; Coffman, D. J.; Eck, T. F.

    2014-10-01

    The spectral deconvolution algorithm (SDA) and SDA+ (extended SDA) methodologies can be employed to separate the fine and coarse mode extinction coefficients from measured total aerosol extinction coefficients, but their common use is currently limited to AERONET (AErosol RObotic NETwork) aerosol optical depth (AOD). Here we provide the verification of the SDA+ methodology on a non-AERONET aerosol product, by applying it to fine and coarse mode nephelometer and particle soot absorption photometer (PSAP) data sets collected in the marine boundary layer. Using data sets collected on research vessels by NOAA-PMEL(National Oceanic and Atmospheric Administration - Pacific Marine Environmental Laboratory), we demonstrate that with accurate input, SDA+ is able to predict the fine and coarse mode scattering and extinction coefficient partition in global data sets representing a range of aerosol regimes. However, in low-extinction regimes commonly found in the clean marine boundary layer, SDA+ output accuracy is sensitive to instrumental calibration errors. This work was extended to the calculation of coarse and fine mode scattering coefficients with similar success. This effort not only verifies the application of the SDA+ method to in situ data, but by inference verifies the method as a whole for a host of applications, including AERONET. Study results open the door to much more extensive use of nephelometers and PSAPs, with the ability to calculate fine and coarse mode scattering and extinction coefficients in field campaigns that do not have the resources to explicitly measure these values.

  6. Initial investigation of the wavelength dependence of optical properties measured with a new multi-pass Aerosol Extinction Differential Optical Absorption Spectrometer (AE-DOAS)

    NASA Astrophysics Data System (ADS)

    Chartier, R. T.; Greenslade, M. E.

    2012-04-01

    Atmospheric aerosols directly affect climate by scattering and absorbing radiation. The magnitude of the impact is dependent upon the wavelength of light, but is often estimated near 550 nm. When light scattering and absorption by aerosols is approximated, the wavelength dependence of the refractive index for specific components is lost. As a result, climate models would have inherent uncertainties for aerosol contributions to radiative forcing when considering the entire solar spectrum. An aerosol extinction differential optical absorption spectrometer has been developed to directly measure aerosol extinction at mid-ultraviolet to near infrared wavelengths. The instrument consists of a spectrometer coupled to a closed White-type multi-pass gas cell with an adjustable path length of up to approximately 20 m. Laboratory measurements of various gases are compared with known absorption cross sections. Additionally, the extinction of monodisperse samples of polystyrene latex spheres are measured and compared to Mie theory generated with refractive index values from the literature to validate the new instrument. The polystyrene experiments also emphasize the ability of the new instrument to retrieve the wavelength dependent refractive index, especially in the ultraviolet wavelength regions where variability is expected. The spectrometer will be a significant advancement for determining wavelength dependent complex refractive indices in future laboratory studies as well as provide the ability to monitor ambient aerosol light extinction.

  7. Initial investigation of the wavelength dependence of optical properties measured with a new multi-pass aerosol extinction differential optical absorption spectrometer (AE-DOAS)

    NASA Astrophysics Data System (ADS)

    Chartier, R. T.; Greenslade, M. E.

    2011-10-01

    Atmospheric aerosols directly affect climate by scattering and absorbing radiation. The magnitude of the impact is dependent upon the wavelength of light, but is often estimated near 550 nm. When light scattering and absorption by aerosols is approximated, the wavelength dependence of the refractive index for specific components is lost. As a result, climate models would have inherent uncertainties for aerosol contributions to radiative forcing when considering the entire solar spectrum. An aerosol extinction differential optical absorption spectrometer has been developed to directly measure aerosol extinction at mid-ultraviolet to near infrared wavelengths. The instrument consists of a spectrometer coupled to a closed White-type multi-pass gas cell with an adjustable path length of up to approximately 20 m. Laboratory measurements of various gases are compared with known absorption cross sections. Additionally, the extinction of monodisperse samples of polystyrene latex spheres are measured and compared to Mie theory generated with refractive index values from the literature to validate the new instrument. The polystyrene experiments also emphasize the ability of the new instrument to retrieve the wavelength dependent refractive index, especially in the ultraviolet wavelength regions where variability is expected. The spectrometer will be a significant advancement for determining wavelength dependent complex refractive indices in future laboratory studies as well as provide the ability to monitor ambient aerosol light extinction.

  8. A broadband cavity-enhanced spectrometer for measuring the extinction of aerosols at blue and near-UV wavelengths

    NASA Astrophysics Data System (ADS)

    Venables, Dean; Fullam, Donovan; Hoa Le, Phuoc; Chen, Jun; Böge, Olaf; Herrmann, Hartmut

    2016-04-01

    We describe a new broadband cavity-enhanced absorption spectrometer for sensitive extinction measurements of aerosols. The instrument is distinguished by its broad and continuous spectral coverage from the near-UV to blue wavelengths (ca. 320 to 450 nm). The short wavelength region has been little explored compared to visible wavelengths, but is important because (1) brown carbon (BrC) absorbs strongly in this wavelength region, and (2) absorption of near-UV radiation in the atmosphere alters the photolysis rate of the key atmospheric species O3, NO2, and HONO, with implications for air quality and atmospheric oxidation capacity. The instrument performance and the effect of a switchable in-line filter are characterised. Early results using the instrument in the TROPOS atmospheric simulation chamber are presented. These experiments include studies of secondary organic aerosol formation (SOA), and biomass burning experiments of rice and wheat straw, followed by experiments simulating particle aging under daytime and nighttime conditions.

  9. Aerosol Classification using Airborne High Spectral Resolution Lidar Measurements

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

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

  10. Simulation model of scattering properties and extinction of laser light applied to urban aerosols over the city of Cali, Colombia

    NASA Astrophysics Data System (ADS)

    Rodríguez, Edith; Montilla, Elena; Jaramillo, Mauricio; Solarte, Efraín; Bastidas, Alvaro

    2005-10-01

    Aerosols are among the most spatially variable components of the atmosphere, and thus their study requires their monitoring over a broad geographic range. The backscattering of light from suspended solid and liquid particles in the atmosphere obeys Mie scattering theory. Light attenuation in the spectral region from 300 to 4000 nm due to Mie scattering exceeds that due to molecular (Rayleigh) scattering and ozone absorption combined. This occurs despite the fact that aerosol particle concentrations in the atmosphere are many orders of magnitude smaller than molecular concentrations. Starting from the characteristics of urban aerosols measured over the city of Cali (Colombia), 3° 30' N, 76° 30' W, with a PM10 particle selector, along with information on meteorological conditions typical of the region, we present the results of a study of light scattering properties generated using a model applied Mie scattering theory to size parameter between 0 and 50, with an increment of 0.01, and Matlab computer code, to simulate and predict measurements with a Lidar system operating at 532 nm.

  11. Extinction coefficient (1 micrometer) properties of high-altitude clouds from solar occultation measurements (1985-1990): Evidence of volcanic aerosol effect

    NASA Technical Reports Server (NTRS)

    Wang, Pi-Huan; Minnis, Patrick; Yue, Glenn K.

    1995-01-01

    The properties of the 1-micrometer volume extinction coefficient of two geographically different high-altitude cloud systems have been examined for the posteruption period (1985-1990) of the April 1982 El Chichon volcanic event with emphasis on the effect of volcanic aerosols on clouds. These two high-altitude cloud systems are the tropical clouds in the tropopause region observed by the Stratospheric Aerosol and Gas Experiment (SAGE) 2 and the polar stratospheric clouds (PSCs) sighted by the Stratospheric Aerosol Measurement (SAM) 2. The results indicate that volcanic aerosols alter the frequency distributions of these high-altitude clouds in such a manner that the occurrence of clouds having high extinction coefficients (6 x 10(exp -3) - 2 x 10(exp -2)/km) is suppressed, while that of clouds having low extinction coefficients (2 x 10(exp -3) - 6 x 10(exp -2)/km) is enhanced. This influence of the volcanic aerosols appears to be opposite to the increase in the extinction coefficient of optically thick clouds observed by the Earth Radiation Budget Experiment (ERBE) during the initial posteruption period of the June 1991 Pinatubo eruption. A plausible explanation of this difference, based on the Mie theory, is presented. As a consequence of the Mie theory, the effective radius of most, if not all, of the high-altitude clouds, measured by the SAGE series of satellite instruments must be less than about 0.8 micrometers. This mean cloud particle size implied by the satellite extinction-coefficient data at a single wavelength (1 micrometer) is further substantiated by the particle size analysis based on cloud extinction coefficient at two wavelengths (0.525 and 1.02 micrometers) obtained by the SAGE 2 observations. Most of the radiation measured by ERBE is reflected by cloud systems comprised of particles having effective radii much greater than 1 micrometer. A reduction in the effective radius of these clouds due to volcanic aerosols is expected to increase their

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

    NASA Astrophysics Data System (ADS)

    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

    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

  13. 1064 nm rotational Raman lidar for particle extinction and lidar-ratio profiling: cirrus case study

    NASA Astrophysics Data System (ADS)

    Haarig, Moritz; Engelmann, Ronny; Ansmann, Albert; Veselovskii, Igor; Whiteman, David N.; Althausen, Dietrich

    2016-09-01

    For the first time, vertical profiles of the 1064 nm particle extinction coefficient obtained from Raman lidar observations at 1058 nm (nitrogen and oxygen rotational Raman backscatter) are presented. We applied the new technique in the framework of test measurements and performed several cirrus observations of particle backscatter and extinction coefficients, and corresponding extinction-to-backscatter ratios at the wavelengths of 355, 532, and 1064 nm. The cirrus backscatter coefficients were found to be equal for all three wavelengths keeping the retrieval uncertainties in mind. The multiple-scattering-corrected cirrus extinction coefficients at 355 nm were on average about 20-30 % lower than the ones for 532 and 1064 nm. The cirrus-mean extinction-to-backscatter ratio (lidar ratio) was 31 ± 5 sr (355 nm), 36 ± 5 sr (532 nm), and 38 ± 5 sr (1064 nm) in this single study. We further discussed the requirements needed to obtain aerosol extinction profiles in the lower troposphere at 1064 nm with good accuracy (20 % relative uncertainty) and appropriate temporal and vertical resolution.

  14. Design Of A Novel Open-Path Aerosol Extinction Cavity Ringdown Spectrometer And Initial Data From Deployment At NOAA's Atmospheric Observatory

    NASA Astrophysics Data System (ADS)

    Gordon, T. D.; Wagner, N. L.; Richardson, M.; Law, D. C.; Wolfe, D. E.; Brock, C. A.; Erdesz, F.; Murphy, D. M.

    2014-12-01

    The ability to frame effective climate change policy depends strongly on reducing the uncertainty in aerosol radiative forcing, which is currently nearly as great as best estimates of its magnitude. Achieving this goal will require significant progress in measuring aerosol properties, including aerosol optical depth, single scattering albedo and the effect of relative humidity on these properties for both fine and coarse particles. However both ground- and space-based instruments fail or are highly biased in the presence of clouds, severely limiting quantitative estimates of the radiative effects of aerosols where they are advected over low-level clouds. Moreover, many in situ aerosol measurements exclude the coarse fraction, which can be very important in and downwind of desert regions. By measuring the decay rate of a pulsed laser in an optically resonant cavity, cavity ringdown spectrometers (CRDSs) have been employed successfully in measuring aerosol extinction for particles in relative humidities below 90%. At very high humidities (as found in and near clouds), however, existing CRDSs perform poorly, diverging significantly from theoretical extinction values as humidities approach 100%. The new open-path aerosol extinction CRDS described in this poster measures extinction as aerosol is drawn through the sample cavity directly without inlets or tubing for channeling the flow, which cause particle losses, condensation at high RH and other artifacts. This poster presents the key elements of the new open-path CRDS design as well as comparisons with an earlier generation closed-path CRDS and preliminary data obtained during a field study at the 300 meter tower at NOAA's Boulder Atmospheric Observatory (BAO) in Colorado.

  15. A comparison of measured and calculated optical properties of atmospheric aerosols at infrared wavelengths

    NASA Technical Reports Server (NTRS)

    Rosen, James M.

    1991-01-01

    Measurements of 10.6-micron lidar backscatter were compared with calculated backscatter based on nearly simultaneous observations of stratospheric and tropospheric aerosol size distributions. It was found that there is better agreement in the troposphere, even though the uncertainties of the calculation are greater for this region due to the variables in both the spatial concentration and the physical makeup of the aerosol. A second comparison study was made to test the consistency of the mean tropospheric extinction values at 1.02 micron (as reported by the SAGE satellite) with the values calculated from an ensemble of 400 measured size distributions thought to be representative of midcontinental tropospheric aerosol. The two methods produce consistent results within the expected degree of uncertainty. The ensemble of 400 'proven' size distributions is then used to calculate a statistical relationship between the 1.02-micron extinction and the 10.6-micron backscatter.

  16. Altitude Differentiated Aerosol Extinction Over Tenerife (North Atlantic Coast) During ACE-2 by Means of Ground and Airborne Photometry and Lidar Measurements

    NASA Technical Reports Server (NTRS)

    Formenti, P.; Elias, T.; Welton, J.; Diaz, J. P.; Exposito, F.; Schmid, B.; Powell, D.; Holben, B. N.; Smirnov, A.; Andreae, M. O.; Devaux, C.; Voss, K.; Lelieveld, J.; Livingston, J. M.; Russell, P. B.; Durkee, P. A.

    2000-01-01

    Retrievals of spectral aerosol optical depths (tau(sub a)) by means of sun photometers have been undertaken in Tenerife (28 deg 16' N, 16 deg 36' W) during ACE-2 (June-July 1997). Five ground-based sites were located at four different altitudes in the marine boundary layer and in the free troposphere, from 0 to 3570 m asl. The goal of the investigation was to provide estimates of the vertical aerosol extinction over the island, both under clean and turbid conditions. Inversion of spectral tau(sub a) allowed to retrieve size distributions, from which the single scattering albedo omega(sub 0) and the asymmetry factor g could be estimated as a function of altitude. These parameters were combined to calculate aerosol forcing in the column. Emphasis is put on episodes of increased turbidity, which were observed at different locations simultaneously, and attributed to outbreaks of mineral dust from North Africa. Differentiation of tau(sub a) as a function of altitude provided the vertical profile of the extinction coefficient sigma(sub e). For dust outbreaks, aerosol extinction is concentrated in two distinct layers above and below the strong subsidence inversion around 1200 m asl. Vertical profiles of tau(sub a) and sigma(sub e) are shown for July 8. In some occasions, vertical profiles are compared to LIDAR observations, performed both at sea level and in the low free troposphere, and to airborne measurements of aerosol optical depths.

  17. Determination of the Aerosol Size Distribution by Analytic Inversion of the Extinction Spectrum in the Complex Anomalous Diffraction Approximation

    NASA Astrophysics Data System (ADS)

    Franssens, Ghislain; de Maziére, Martine; Fonteyn, Dominique

    2000-08-01

    A new derivation is presented for the analytical inversion of aerosol spectral extinction data to size distributions. It is based on the complex analytic extension of the anomalous diffraction approximation (ADA). We derive inverse formulas that are applicable to homogeneous nonabsorbing and absorbing spherical particles. Our method simplifies, generalizes, and unifies a number of results obtained previously in the literature. In particular, we clarify the connection between the ADA transform and the Fourier and Laplace transforms. Also, the effect of the particle refractive-index dispersion on the inversion is examined. It is shown that, when Lorentz s model is used for this dispersion, the continuous ADA inverse transform is mathematically well posed, whereas with a constant refractive index it is ill posed. Further, a condition is given, in terms of Lorentz parameters, for which the continuous inverse operator does not amplify the error.

  18. Changes in surface aerosol extinction trends over China during 1980-2013 inferred from quality-controlled visibility data

    NASA Astrophysics Data System (ADS)

    Li, Jing; Li, Chengcai; Zhao, Chunsheng; Su, Tianning

    2016-08-01

    Pollution in China has been attracting extensive attention both globally and regionally, especially due to the perceptually worsening "smog" condition in recent years. We use routine visibility measurements from 1980 to 2013 at 272 World Meteorological Organization stations in China to assess the temporal changes in the magnitude and the sign of pollution trends. A strict and comprehensive quality control procedure is enforced by considering several issues not typically addressed in previous studies. Two methods are used to independently estimate the trend and its significance level. Results show that, in general, a strong increase in aerosol extinction coefficient over the majority of China is observed in the 1980s, followed by a moderate decrease in the 1990s, another increase in the 2000s, and a shift to decrease since around 2006 for some regions. Seasonally, winter and fall trends appear to be the strongest, while summer has the lowest trend.

  19. Determination of the aerosol size distribution by analytic inversion of the extinction spectrum in the complex anomalous diffraction approximation.

    PubMed

    Franssens, G; De Maziére, M; Fonteyn, D

    2000-08-20

    A new derivation is presented for the analytical inversion of aerosol spectral extinction data to size distributions. It is based on the complex analytic extension of the anomalous diffraction approximation (ADA). We derive inverse formulas that are applicable to homogeneous nonabsorbing and absorbing spherical particles. Our method simplifies, generalizes, and unifies a number of results obtained previously in the literature. In particular, we clarify the connection between the ADA transform and the Fourier and Laplace transforms. Also, the effect of the particle refractive-index dispersion on the inversion is examined. It is shown that, when Lorentz's model is used for this dispersion, the continuous ADA inverse transform is mathematically well posed, whereas with a constant refractive index it is ill posed. Further, a condition is given, in terms of Lorentz parameters, for which the continuous inverse operator does not amplify the error.

  20. Four-year long-path monitoring of ambient aerosol extinction at a central European urban site: dependence on relative humidity

    NASA Astrophysics Data System (ADS)

    Skupin, A.; Ansmann, A.; Engelmann, R.; Seifert, P.; Müller, T.

    2015-04-01

    The ambient aerosol particle extinction coefficient is measured with the Spectral Aerosol Extinction Monitoring System (SÆMS) along a 2.84 km horizontal path at 30-50 m height above ground in the urban environment of Leipzig (51.3° N, 12.4° E), Germany, since 2009. The dependence of the particle extinction coefficient (wavelength range from 300-1000 nm) on relative humidity up to almost 100% was investigated. The main results are presented. For the wavelength of 550 nm, the mean extinction enhancement factor was found to be 1.75 ± 0.4 for an increase of relative humidity from 40 to 80%. The respective four-year mean extinction enhancement factor is 2.8 ± 0.6 for a relative-humidty increase from 40 to 95%. A parameterization of the dependency of the urban particle extinction coefficient on relative humidity is presented. A mean hygroscopic exponent of 0.463 for the 2009-2012 period was determined. Based on a backward trajectory cluster analysis, the dependence of several aerosol optical properties for eight air flow regimes was investigated. Large differences were not found indicating that local pollution sources widely control the aerosol conditions over the urban site. The comparison of the SÆMS extinction coefficient statistics with respective statistics from ambient AERONET sun photometer observations yield good agreement. Also, time series of the particle extinction coefficient computed from in-situ-measured dry particle size distributions and humidity-corrected SÆMS extinction values (for 40% relative humidity) were found in good overall consistency, which corroborates the applicability of the developed humidity parameterization scheme. The analysis of the spectral dependence of particle extinction (Ångström exponent) revealed an increase of the 390-881 nm Ångström exponent from, on average, 0.3 (at 30% relative humidity) to 1.3 (at 95% relative humidity) for the four-year period.

  1. The CU Airborne MAX-DOAS instrument: ground based validation, and vertical profiling of aerosol extinction and trace gases

    NASA Astrophysics Data System (ADS)

    Baidar, S.; Oetjen, H.; Coburn, S.; Dix, B.; Ortega, I.; Sinreich, R.; Volkamer, R.

    2012-09-01

    The University of Colorado Airborne Multi Axis Differential Optical Absorption Spectroscopy (CU AMAX-DOAS) instrument uses solar stray light remote sensing to detect and quantify multiple trace gases, including nitrogen dioxide (NO2), glyoxal (CHOCHO), formaldehyde (HCHO), water vapor (H2O), nitrous acid (HONO), iodine monoxide (IO), bromine monoxide (BrO), and oxygen dimers (O4) at multiple wavelengths (360 nm, 477 nm, 577 nm and 632 nm) simultaneously, and sensitively in the open atmosphere. The instrument is unique, in that it presents the first systematic implementation of MAX-DOAS on research aircraft, i.e. (1) includes measurements of solar stray light photons from nadir, zenith, and multiple elevation angles forward and below the plane by the same spectrometer/detector system, and (2) features a motion compensation system that decouples the telescope field of view (FOV) from aircraft movements in real-time (< 0.35° accuracy). Sets of solar stray light spectra collected from nadir to zenith scans provide some vertical profile information within 2 km above and below the aircraft altitude, and the vertical column density (VCD) below the aircraft is measured in nadir view. Maximum information about vertical profiles is derived simultaneously for trace gas concentrations and aerosol extinction coefficients over similar spatial scales and with a vertical resolution of typically 250 m during aircraft ascent/descent. The instrument is described, and data from flights over California during the CalNex and CARES air quality field campaigns is presented. Horizontal distributions of NO2 VCDs (below the aircraft) maps are sampled with typically 1 km resolution, and show good agreement with two ground based CU MAX-DOAS instruments (slope 0.95 ± 0.09, R2 = 0.86). As a case study vertical profiles of NO2, CHOCHO, HCHO, and H2O mixing ratios and aerosol extinction coefficients, ɛ, at 477nm calculated from O4 measurements from a low approach at Brackett airfield inside the

  2. Aerosol Extinction Transmissometry at Visible and Infrared Wavelengths Applied to Specialized Problems in CB Defense

    DTIC Science & Technology

    1989-10-01

    Transmission of Light Through Fog." Phy. hev= 38, 159-165 (1931). 30, Kerker, M., Matijevic . E., Espenscheid. W.F., Farone, W.A., and Kitani, S...W.F., Matijevic , E., and Kerker, M., "Aerosol Studies by Light Scattering. III. Preparation and Particle Size Analysis of Sodium Chloride t.arosols of

  3. Field test of a new instrument to measure UV/Vis (300-700 nm) ambient aerosol extinction spectra in Colorado during DISCOVER-AQ

    NASA Astrophysics Data System (ADS)

    Jordan, C. E.; Anderson, B. E.; Beyersdorf, A. J.; Dibb, J. E.; Greenslade, M. E.; Martin, R.; Scheuer, E. M.; Shook, M.; Thornhill, K. L., II; Troop, D.; Winstead, E.; Ziemba, L. D.

    2014-12-01

    An optical instrument has been developed to investigate aerosol extinction spectra in the ambient atmosphere. Based on a White-type cell design and using a differential optical approach, aerosol extinction spectra over the 300-700 nm ultraviolet and visible (UV/Vis) wavelength range are obtained. Laboratory tests conducted at NASA Langley Research Center (NASA LaRC) in March 2014 showed good agreement with Cavity Attenuated Phase Shift (CAPS PMex, Aerodyne Research) extinction measurements (at 450, 530, and 630 nm) for a variety of aerosols, e.g., scatterers such as polystyrene latex spheres and ammonium sulfate; absorbers such as dust (including pigmented minerals), smoke (generated in a miniCAST burning propane) and laboratory smoke analogs (e.g., fullerene soot and aquadag). The instrument was field tested in Colorado in July and August 2014 aboard the NASA mobile laboratory at various ground sites during the DISCOVER-AQ (Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality) field campaign. A description of the instrument, results from the laboratory tests, and summer field data will be presented. The instrument provides a new tool for probing in situ aerosol optical properties that may help inform remote sensing approaches well into the UV range.

  4. Utilizing The Synergy of Airborne Backscatter Lidar and In-Situ Measurements for Evaluating CALIPSO

    NASA Astrophysics Data System (ADS)

    Tsekeri, Alexandra; Amiridis, Vassilis; Marenco, Franco; Marinou, Eleni; Rosenberg, Phil; Solomos, Stavros; Trembath, Jamie; Allan, James; Bacak, Asan; Nenes, Athanasios

    2016-06-01

    Airborne campaigns dedicated to satellite validation are crucial for the effective global aerosol monitoring. CALIPSO is currently the only active remote sensing satellite mission, acquiring the vertical profiles of the aerosol backscatter and extinction coefficients. Here we present a method for CALIPSO evaluation from combining lidar and in-situ airborne measurements. The limitations of the method have to do mainly with the in-situ instrumentation capabilities and the hydration modelling. We also discuss the future implementation of our method in the ICE-D campaign (Cape Verde, August 2015).

  5. Aerosol optical extinction during the Front Range Air Pollution and Photochemistry Éxperiment (FRAPPÉ) 2014 summertime field campaign, Colorado, USA

    NASA Astrophysics Data System (ADS)

    Dingle, Justin H.; Vu, Kennedy; Bahreini, Roya; Apel, Eric C.; Campos, Teresa L.; Flocke, Frank; Fried, Alan; Herndon, Scott; Hills, Alan J.; Hornbrook, Rebecca S.; Huey, Greg; Kaser, Lisa; Montzka, Denise D.; Nowak, John B.; Reeves, Mike; Richter, Dirk; Roscioli, Joseph R.; Shertz, Stephen; Stell, Meghan; Tanner, David; Tyndall, Geoff; Walega, James; Weibring, Petter; Weinheimer, Andrew

    2016-09-01

    Summertime aerosol optical extinction (βext) was measured in the Colorado Front Range and Denver metropolitan area as part of the Front Range Air Pollution and Photochemistry Éxperiment (FRAPPÉ) campaign during July-August 2014. An Aerodyne cavity attenuated phase shift particle light extinction monitor (CAPS-PMex) was deployed to measure βext (at average relative humidity of 20 ± 7 %) of submicron aerosols at λ = 632 nm at 1 Hz. Data from a suite of gas-phase instrumentation were used to interpret βext behavior in various categories of air masses and sources. Extinction enhancement ratios relative to CO (Δβext / ΔCO) were higher in aged urban air masses compared to fresh air masses by ˜ 50 %. The resulting increase in Δβext / ΔCO for highly aged air masses was accompanied by formation of secondary organic aerosols (SOAs). In addition, the impacts of aerosol composition on βext in air masses under the influence of urban, natural oil and gas operations (O&G), and agriculture and livestock operations were evaluated. Estimated non-refractory mass extinction efficiency (MEE) values for different air mass types ranged from 1.51 to 2.27 m2 g-1, with the minimum and maximum values observed in urban and agriculture-influenced air masses, respectively. The mass distribution for organic, nitrate, and sulfate aerosols presented distinct profiles in different air mass types. During 11-12 August, regional influence of a biomass burning event was observed, increasing the background βext and estimated MEE values in the Front Range.

  6. Inherent calibration of a novel LED-CE-DOAS instrument to measure iodine oxide, glyoxal, methyl glyoxal, nitrogen dioxide, water vapour and aerosol extinction in open cavity mode

    NASA Astrophysics Data System (ADS)

    Thalman, R.; Volkamer, R.

    2010-06-01

    The combination of Cavity Enhanced Absorption Spectroscopy (CEAS) with broad-band light sources (e.g. Light-Emitting Diodes, LEDs) lends itself to the application of cavity enhanced Differential Optical Absorption Spectroscopy (CE-DOAS) to perform sensitive and selective point measurements of multiple trace gases and aerosol extinction with a single instrument. In contrast to other broad-band CEAS techniques, CE-DOAS relies only on the measurement of relative intensity changes, i.e. does not require knowledge of the light intensity in the absence of trace gases and aerosols (I0). We have built a prototype LED-CE-DOAS instrument in the blue spectral range (420-490 nm) to measure nitrogen dioxide (NO2), glyoxal (CHOCHO), methyl glyoxal (CH3COCHO), iodine oxide (IO), water vapour (H2O) and oxygen dimers (O4). We demonstrate the first CEAS detection of methyl glyoxal, and the first CE-DOAS detection of CHOCHO and IO. A further innovation consists in the measurement of extinction losses from the cavity, e.g. due to aerosols, at two wavelengths by observing O4 (477 nm) and H2O (443 nm) and measuring the pressure, relative humidity and temperature independently. This approach is demonstrated by experiments where laboratory aerosols of known size and refractive index were generated and their extinction measured. The measured extinctions were then compared to the theoretical extinctions calculated using Mie theory (3-7×10-7 cm-1). Excellent agreement is found from both the O4 and H2O retrievals. This enables the first inherently calibrated CEAS measurement in open cavity mode (mirrors facing the open atmosphere), and eliminates the need for sampling lines to supply air to the cavity, and/or keep the cavity enclosed and aerosol free. Measurements in open cavity mode are demonstrated for CHOCHO, CH3COCHO, NO2, H2O and aerosol extinction at 477 nm and 443 nm. Our prototype LED-CE-DOAS provides a low cost, yet research grade innovative instrument for applications in simulation

  7. A Lidar and Backscatter Sonde Aerosol Measurement Campaign at Table Mountain During February-March 1997: Observations of Stratospheric Background Aerosols and Cirrus Clouds

    NASA Technical Reports Server (NTRS)

    Beyerle, G.; Gross, M.; Haner, D.; Kjome, N.; McDermid, I.; McGee, T.; Rosen, J.; Schafer, H. J.; Schrems, O.

    1999-01-01

    Altitude profiles of backscater ratio of the stratospheric background aerosol layer at altitudes between 15 and 25 km and high-altitude cirrus clouds at altitudes below 13 km are analyzed and discussed. Cirrus clouds were present on 16 of the 26 campaign nights.

  8. Lidar extinction measurement in the mid infrared

    NASA Astrophysics Data System (ADS)

    Mitev, Valentin; Babichenko, S.; Borelli, R.; Fiorani, L.; Grigorov, I.; Nuvoli, M.; Palucci, A.; Pistilli, M.; Puiu, Ad.; Rebane, Ott; Santoro, S.

    2014-11-01

    We present a lidar measurement of atmospheric extinction coefficient. The measurement is performed by inversion of the backscatter lidar signal at wavelengths 3'000nm and 3'500nm. The inversion of the backscatter lidar signal was performed with constant extinction-to-backscatter ration values of 104 and exponential factor 0.1.

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

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

    Micro-pulse lidar systems (MPL) were used to measure aerosol properties during the Indian Ocean Experiment (INDOEX) 1999 field phase. Measurements were made from two platforms: the NOAA ship RN Ronald H. Brown, and the Kaashidhoo Climate Observatory (KCO) in the Maldives. Sunphotometers were used to provide aerosol optical depths (AOD) needed to calibrate the MPL. This study focuses on the height distribution and optical properties (at 523 nm) of aerosols observed during the campaign. The height of the highest aerosols (top height) was calculated and found to be below 4 km for most of the cruise. The marine boundary layer (MBL) top was calculated and found to be less than 1 km. MPL results were combined with air mass trajectories, radiosonde profiles of temperature and humidity, and aerosol concentration and optical measurements. Humidity varied from approximately 80% near the surface to 50% near the top height during the entire cruise. The average value and standard deviation of aerosol optical parameters were determined for characteristic air mass regimes. Marine aerosols in the absence of any continental influence were found to have an AOD of 0.05 +/- 0.03, an extinction-to-backscatter ratio (S-ratio) of 33 +/- 6 sr, and peak extinction values around 0.05/km (near the MBL top). The marine results are shown to be in agreement with previously measured and expected values. Polluted marine areas over the Indian Ocean, influenced by continental aerosols, had AOD values in excess of 0.2, S-ratios well above 40 sr, and peak extinction values approximately 0.20/km (near the MBL top). The polluted marine results are shown to be similar to previously published values for continental aerosols. Comparisons between MPL derived extinction near the ship (75 m) and extinction calculated at ship-level using scattering measured by a nephelometer and absorption using a PSAP were conducted. The comparisons indicated that the MPL algorithm (using a constant S-ratio throughout the

  10. Aerosol Products from The Future Space Lidar AEOLUS

    NASA Astrophysics Data System (ADS)

    Martinet, Pauline; Dabas, Alain; Lever, Vincent; Flamant, Pierre; Huber, Dorit

    2016-06-01

    Ready for launch by the end of 2016, the Doppler lidar mission AEOLUS from the European Space Agency (ESA) will be the first High-Spectral Resolution Lidar (HSRL) in space. Operating in the UV, it implements two detection channels for aerosol and molecular backscatter. The system is primarily designed for the measurement of winds, but the HSRL capability enables the measurement of the particulate backscatter and extinction coefficients without any a priori assumption on the aerosol type. The level-2A (L2A) processor has been developed for these measurements and tested with synthetic data. The results show good aerosol backscatter profiles can be retrieved. Extinction coefficients are reasonable but do not reach the quality of backscatter coefficients. A precise, full, radiometric calibration of the lidar is required. A major limitation of the system is a single polarization component of the light is detected leading to an underestimation of backscatter coefficients when the atmospheric particles are depolarizing. The vertical resolution goes from 250 meters in the lowest part of the atmosphere, to 2 km in the lower stratosphere. The maximum altitude can reach above 20km. The basic horizontal averaging is 90km. Averaging on shorter distances (down to a few km) are possible but require a sufficient signal to noise ratio.

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

    NASA Astrophysics Data System (ADS)

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

    2007-12-01

    A Raman/elastic lidar for tropospheric aerosol study is operational at CNR-IMAA (40°36'N, 15°44'E, 760 m above sea level) since May 2000 in the framework of EARLINET. Since August 2005, this system provides aerosol backscatter coefficient profiles at 1064 nm, and independent measurements of aerosol extinction and backscatter coefficient profiles at 355 and 532 nm. In this way, lidar ratio (i.e. extinction to backscatter ratio) profiles at 355 and 532 nm are also obtained. In addition, depolarization ratio measurements at 532 nm are obtained by means of detection of components of backscattered light polarized perpendicular and parallel to the direction of the linearly polarized transmitted laser beam. Depolarization ratio measurements provide information about shape and orientation of aerosolic particles, while lidar ratio measurements and wavelength dependences of both backscatter and extinction are important for aerosol characterization in terms of aerosol type and size. In addition, high quality multi-wavelength measurements (3 backscatter + 2 extinction) can allow the determination of microphysical aerosol properties (refractive index, single-scattering albedo and effective particles radii). Systematic measurements are performed three times per week according to the EARLINET schedule since May 2000, and further measurements are performed in order to investigate particular events, like dust intrusions, volcanic eruptions and forest fires. This extended dataset allows the optical characterization of aerosol located close to the surface, namely in the Planetary Boundary Layer, as well as in the free troposphere. In the free troposphere, an high occurrence of Saharan dust intrusions at CNR-IMAA (about 1 day of Saharan dust intrusion every 10 days) has been identified by means of back-trajectory analysis and in accordance with satellite images, because of the short distance from the Sahara region. In addition, CNR-IMAA is pretty close to Etna, the largest European

  12. Optical and physical properties of stratospheric aerosols from balloon measurements in the visible and near-infrared domains. 1. Analysis of aerosol extinction spectra from the AMON and SALOMON balloonborne spectrometers.

    PubMed

    Berthet, Gwenaël; Renard, Jean-Baptiste; Brogniez, Colette; Robert, Claude; Chartier, Michel; Pirre, Michel

    2002-12-20

    Aerosol extinction coefficients have been derived in the 375-700-nm spectral domain from measurement in the stratosphere since 1992, at night, at mid- and high latitudes from 15 to 40 km, by two balloonborne spectrometers, Absorption par les Minoritaires Ozone et NO(chi) (AMON) and Spectroscopie d'Absorption Lunaire pour l'Observation des Minoritaires Ozone et NO(chi) (SALOMON). Log-normal size distributions associated with the Mie-computed extinction spectra that best fit the measurements permit calculation of integrated properties of the distributions. Although measured extinction spectra that correspond to background aerosols can be reproduced by the Mie scattering model by use of monomodal log-normal size distributions, each flight reveals some large discrepancies between measurement and theory at several altitudes. The agreement between measured and Mie-calculated extinction spectra is significantly improved by use of bimodal log-normal distributions. Nevertheless, neither monomodal nor bimodal distributions permit correct reproduction of some of the measured extinction shapes, especially for the 26 February 1997 AMON flight, which exhibited spectral behavior attributed to particles from a polar stratospheric cloud event.

  13. Optical and physical properties of stratospheric aerosols from balloon measurements in the visible and near-infrared domains. I. Analysis of aerosol extinction spectra from the AMON and SALOMON balloonborne spectrometers

    NASA Astrophysics Data System (ADS)

    Berthet, Gwenaël; Renard, Jean-Baptiste; Brogniez, Colette; Robert, Claude; Chartier, Michel; Pirre, Michel

    2002-12-01

    Aerosol extinction coefficients have been derived in the 375-700-nm spectral domain from measurements in the stratosphere since 1992, at night, at mid- and high latitudes from 15 to 40 km, by two balloonborne spectrometers, Absorption par les Minoritaires Ozone et NOx (AMON) and Spectroscopie d'Absorption Lunaire pour l'Observation des Minoritaires Ozone et NOx (SALOMON). Log-normal size distributions associated with the Mie-computed extinction spectra that best fit the measurements permit calculation of integrated properties of the distributions. Although measured extinction spectra that correspond to background aerosols can be reproduced by the Mie scattering model by use of monomodal log-normal size distributions, each flight reveals some large discrepancies between measurement and theory at several altitudes. The agreement between measured and Mie-calculated extinction spectra is significantly improved by use of bimodal log-normal distributions. Nevertheless, neither monomodal nor bimodal distributions permit correct reproduction of some of the measured extinction shapes, especially for the 26 February 1997 AMON flight, which exhibited spectral behavior attributed to particles from a polar stratospheric cloud event.

  14. MAX-DOAS measurements in southern China: retrieval of aerosol extinctions and validation using ground-based in-situ data

    NASA Astrophysics Data System (ADS)

    Li, X.; Brauers, T.; Shao, M.; Garland, R. M.; Wagner, T.; Deutschmann, T.; Wahner, A.

    2010-03-01

    We performed MAX-DOAS measurements during the PRiDe-PRD2006 campaign in the Pearl River Delta region 50 km north of Guangzhou, China, for 4 weeks in June 2006. We used an instrument sampling at 7 different elevation angles between 3° and 90°. During 9 cloud-free days, differential slant column densities (DSCDs) of O4 (O2 dimer) absorptions between 351 nm and 389 nm were evaluated for 6 elevation angles. Here, we show that radiative transfer modeling of the DSCDS can be used to retrieve the aerosol extinction and the height of the boundary layer. A comparison of the aerosol extinction with simultaneously recorded, ground based nephelometer data shows excellent agreement.

  15. Inherent calibration of a blue LED-CE-DOAS instrument to measure iodine oxide, glyoxal, methyl glyoxal, nitrogen dioxide, water vapour and aerosol extinction in open cavity mode

    NASA Astrophysics Data System (ADS)

    Thalman, R.; Volkamer, R.

    2010-12-01

    The combination of Cavity Enhanced Absorption Spectroscopy (CEAS) with broad-band light sources (e.g. Light-Emitting Diodes, LEDs) lends itself to the application of cavity enhanced Differential Optical Absorption Spectroscopy (CE-DOAS) to perform sensitive and selective point measurements of multiple trace gases and aerosol extinction with a single instrument. In contrast to other broad-band CEAS techniques, CE-DOAS relies only on the measurement of relative intensity changes, i.e. does not require knowledge of the light intensity in the absence of trace gases and aerosols (I0). We have built a prototype LED-CE-DOAS instrument in the blue spectral range (420-490 nm) to measure nitrogen dioxide (NO2), glyoxal (CHOCHO), methyl glyoxal (CH3COCHO), iodine oxide (IO), water vapour (H2O) and oxygen dimers (O4). We demonstrate the first direct detection of methyl glyoxal, and the first CE-DOAS detection of CHOCHO and IO. The instrument is further inherently calibrated for light extinction from the cavity by observing O4 or H2O (at 477 nm and 443 nm) and measuring the pressure, relative humidity and temperature independently. This approach is demonstrated by experiments where laboratory aerosols of known size and refractive index were generated and their extinction measured. The measured extinctions were then compared to the theoretical extinctions calculated using Mie theory (3-7 × 10-7cm-1). Excellent agreement is found from both the O4 and H2O retrievals. This enables the first inherently calibrated CEAS measurement at blue wavelengths in open cavity mode, and eliminates the need for sampling lines to supply air to the cavity, i.e., keep the cavity enclosed and/or aerosol free. Measurements in open cavity mode are demonstrated for CHOCHO, CH3COCHO, NO2, H2O and aerosol extinction. Our prototype LED-CE-DOAS provides a low cost, yet research grade innovative instrument for applications in simulation chambers and in the open atmosphere.

  16. [A floating-dust case study based on the vertical distribution of aerosol optical properties].

    PubMed

    Wang, Yuan; Deng, Jun-Ying; Shi, Lan-Hong; Chen, Yong-Hang; Zhang, Qiang; Wang, Sheng; Xu, Ting-Ting

    2014-03-01

    The vertical distribution of aerosol optical properties of a typical floating-dust event on October 19, 2009 in Shanghai was analyzed by using Micro-pulse Lidar (MPL) and the CALIPSO satellite. The results showed that the floating-dust aerosol mainly existed below 2 km of height. The floating-dust aerosol backscatter coefficient ranged from 0 to 0.015 km(-1) x sr(-1), and the MPL extinction coefficient ranged from 0 to 0.32 km(-1). The MPL data showed that the aerosol extinction coefficient first increased and then decreased during the floating-dust event. At the same time, the aerosol layer was constantly lifting. The CALIPSO data showed that a large number of small particles were suspended in air at a height of below 2 km, while the big particles always stayed near the ground (0-0.5 km). At the height of 2-10 km, there was only few aerosols; in the range of 4-6 km, there was a mixture of particles with regular and irregular shapes. The vertical distribution of CALIPSO 532 nm total attenuated backscatter coefficient and MPL normalized relative backscatter signal was basically the same, but the extinction coefficient values gained by them were different. Observations by CALIPSO and MPL together could be more comprehensive and objective for monitoring floating-dust in Shanghai.

  17. 1984-1995 Evolution of Stratospheric Aerosol Size, Surface Area, and Volume Derived by Combining SAGE II and CLAES Extinction Measurements

    NASA Technical Reports Server (NTRS)

    Russell, Philip B.; Bauman, Jill J.

    2000-01-01

    This SAGE II Science Team task focuses on the development of a multi-wavelength, multi- sensor Look-Up-Table (LUT) algorithm for retrieving information about stratospheric aerosols from global satellite-based observations of particulate extinction. The LUT algorithm combines the 4-wavelength SAGE II extinction measurements (0.385 <= lambda <= 1.02 microns) with the 7.96 micron and 12.82 micron extinction measurements from the Cryogenic Limb Array Etalon Spectrometer (CLAES) instrument, thus increasing the information content available from either sensor alone. The algorithm uses the SAGE II/CLAES composite spectra in month-latitude-altitude bins to retrieve values and uncertainties of particle effective radius R(sub eff), surface area S, volume V and size distribution width sigma(sub g).

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

    NASA Astrophysics Data System (ADS)

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

    2012-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2011-09-01

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

  20. Overview of the Cumulus Humilis Aerosol Processing Study

    SciTech Connect

    Berg, Larry K.; Berkowitz, Carl M.; Ogren, John A.; Hostetler, Chris A.; Ferrare, Richard; Dubey, Manvendra K.; Andrews, Elizabeth; Coulter, Richard L.; Hair, John; Hubbe, John M.; Lee, Yin-Nan; Mazzoleni, Claudio; Olfert, Jason N.; Springston, Stephen R.

    2009-11-30

    The primary goal of the Cumulus Humilis Aerosol Processing Study (CHAPS) was to characterize and contrast freshly emitted aerosols below, above, and within fields of cumuli, and to study changes to the cloud microphysical structure within these same cloud fields. The CHAPS is one of very few studies that have had an Aerosol Mass Spectrometer (AMS) sampling downstream of a counter-flow virtual impactor (CVI) inlet on an aircraft, allowing the examination of the chemical composition of the nucleated aerosols within the cumuli. The results from the CHAPS will provide insights into changes in the aerosol chemical and optical properties as aerosols move through shallow cumuli downwind of a moderately sized city. Three instrument platforms were employed during the CHAPS, including the U.S. Department of Energy Gulfstream-1 aircraft, which was equipped for in situ sampling of aerosol optical and chemical properties; the NASA-Langley King Air B200, which carried the downward looking NASA Langley High Spectral Resolution Lidar (HSRL) to measure profiles of aerosol backscatter, extinction, and depolarization between the King Air and the surface; and a surface site equipped for continuous in situ measurements of aerosol properties, profiles of aerosol backscatter, and meteorological conditions including total sky cover and thermodynamic profiles of the atmosphere. In spite of record precipitation over central Oklahoma, a total of eight research flights were made by the G-1, and eighteen by the B200, including special satellite verification flights timed to coincide with NASA satellite A-Train overpasses.

  1. Analysis of Venus Express optical extinction due to aerosols in the upper haze of Venus

    NASA Astrophysics Data System (ADS)

    Parkinson, Christopher; Bougher, Stephen; Mahieux, Arnaud; Tellmann, Silvia; Pätzold, Martin; Vandaele, Ann C.; Wilquet, Valérie; Schulte, Rick; Yung, Yuk; Gao, Peter; Bardeen, Charles

    Observations by the SPICAV/SOIR instruments aboard Venus Express (VEx) have revealed that the Upper Haze of Venus is populated by two particle modes, as reported by Wilquet et al. (J. Geophys. Res., 114, E00B42, 2009; Icarus 217, 2012). Gao et al. (In press, Icarus, 2013) posit that the large mode is made up of cloud particles that have diffused upwards from the cloud deck below, while the smaller mode is generated by the in situ nucleation of meteoric dust. They tested this hypothesis by using version 3.0 of the Community Aerosol and Radiation Model for Atmospheres, first developed by Turco et al. (J. Atmos. Sci., 36, 699-717, 1979) and upgraded to version 3.0 by Bardeen et al. (The CARMA 3.0 microphysics package in CESM, Whole Atmosphere Working Group Meeting, 2011). Using the meteoric dust production profile of Kalashnikova et al. (Geophys. Res. Lett., 27, 3293-3296, 2000), the sulfur/sulfate condensation nuclei production profile of Imamura and Hashimoto (J. Atmos. Sci., 58, 3597-3612, 2001), and sulfuric acid vapor production profile of Zhang et al. (Icarus, 217, 714-739, 2012), they numerically simulate a column of the Venus atmosphere from 40 to 100 km above the surface. Their aerosol number density results agree well with Pioneer Venus Orbiter (PVO) data from Knollenberg and Hunten (J. Geophys. Res., 85, 8039-8058, 1980), while their gas distribution results match that of Kolodner and Steffes below 55 km (Icarus, 132, 151-169, 1998). The resulting size distribution of cloud particles shows two distinct modes, qualitatively matching the observations of PVO. They also observe a third mode in their results with a size of a few microns at 48 km altitude, which appears to support the existence of the controversial third mode in the PVO data. This mode disappears if coagulation is not included in the simulation. The Upper Haze size distribution shows two lognormal-like distributions overlapping each other, possibly indicating the presence of the two distinct

  2. Characterizing the Vertical Distribution of Aerosols Over the ARM SGP Site

    SciTech Connect

    Richard Ferrare, Connor Flynn, David Turner

    2009-05-05

    . Analysis of the aerosol and water vapor data collected by the Raman lidar during the 2003 Aerosol IOP indicated that the sensitivity of the lidar was significantly lower than when the lidar was initially deployed. A detailed analysis after the IOP of the long-term dataset demonstrated that the lidar began degrading in early 2002, and that it lost approximately a factor of 4 in sensitivity between 2002 and 2004. We participated in the development of the remediation plan for the system to restore its initial performance. We conducted this refurbishment and upgrade from May- September 2004. This remediation lead to an increase in the signal-to-noise ratio of 10 and 30 for the Raman lidar's water vapor mixing ratio and aerosol backscatter coefficient data, respectively as compared to the signal strengths when the system was first deployed. The DOE ARM Aerosol Lidar Validation Experiment (ALIVE), which was conducted during September 2005, evaluated the impact of these modifications and upgrades on the SGP Raman lidar measurements of aerosol extinction and optical thickness. The CARL modifications significantly improved the accuracy and temporal resolution of the aerosol measurements. Aerosol extinction profiles measured by the Raman lidar were also used to evaluate aerosol extinction profiles and aerosol optical thickness (AOT) simulated by aerosol models as part of the Aerosol module inter-Comparison in global models (AEROCOM) (http://nansen.ipsl.jussieu.fr/AEROCOM/aerocomhome.html) project. There was a wide range in how the models represent the aerosol extinction profiles over the ARM SGP site, even though the average annual AOT represented by the various models and measured by CARL and the Sun photometer were in general agreement, at least within the standard deviations of the averages. There were considerable differences in the average vertical distributions among the models, even among models that had similar average aerosol optical thickness. Deviations between mean

  3. Aerosol Optical Extinction during the Front Range Air Pollution and Photochemistry Experiment (FRAPPE) 2014 Summertime Field Campaign, Colorado U.S.A.

    NASA Astrophysics Data System (ADS)

    Dingle, J. H.; Vu, K. K. T.; Bahreini, R.; Apel, E. C.; Campos, T. L.; Cantrell, C. A.; Cohen, R. C.; Ebben, C. J.; Flocke, F. M.; Fried, A.; Herndon, S. C.; Hills, A. J.; Hornbrook, R. S.; Huey, L. G.; Kaser, L.; Mauldin, L.; Montzka, D. D.; Nowak, J. B.; Richter, D.; Roscioli, J. R.; Shertz, S.; Stell, M. H.; Tanner, D.; Tyndall, G. S.; Walega, J.; Weibring, P.; Weinheimer, A. J.

    2015-12-01

    Aerosol optical extinction (βext) was measured in the Colorado Front Range Denver Metropolitan Area as part of the summertime air quality airborne field campaign to characterize the influence of sources, photochemical processing, and transport of pollution on local air quality. An Aerodyne Cavity Attenuated Phase Shift particle light extinction monitor (CAPS-PMex) was deployed to measure dry βext at λ=632 nm at 1 Hz. Data from a suite of gas-phase instrumentation were used to interpret the βext under various categories of aged air masses and sources. Extinction enhancement ratios of Δβext/ΔCO were evaluated under 3 differently aged air mass categories (fresh, intermediately aged, and aged) to investigate impacts of photochemistry on βext. Δβext/ΔCO was significantly increased in heavily aged air masses compared to fresh air masses (0.17 Mm-1/ppbv and 0.094 Mm-1/ppbv respectively). The resulting increase in Δβext/ΔCO under heavily aged air masses was represented by secondary organic aerosols (SOA) formation. Aerosol composition and sources from urban, natural oil and gas wells (OG), and agriculture and livestock operations were also evaluated for their impacts on βext. Linear regression fits to βext vs. organic aerosol mass showed higher correlation coefficients under the urban and OG plumes (r=0.55 and r=0.71 respectively) and weakest under agricultural and livestock plumes (r=0.28). The correlation between βext and nitrate aerosol mass however was best under the agriculture and livestock plumes (r=0.81), followed by OG plumes (r=0.74), suggesting co-location of aerosol nitrate precursor sources with OG emissions. Finally, non-refractory mass extinction efficiency (MEE) was analyzed. MEE was observed to be 1.37 g/m2 and 1.30 g/m2 in OG and urban+OG plumes, respectively.

  4. Analysis of Venus Express optical extinction due to aerosols in the upper haze of Venus

    NASA Astrophysics Data System (ADS)

    Parkinson, C. D.; Bougher, S. W.; Schulte, R.; Gao, P.; Yung, Y. L.; Vandaele, A.; Wilquet, V.; Mahieux, A.; Tellmann, S.

    2013-12-01

    Observations by the SPICAV/SOIR instruments aboard the Venus Express (VEx) spacecraft have revealed that the upper haze (UH) of Venus, between 70 and 90 km, is variable on the order of days to weeks and that it is populated by two particle modes. Gao et al. (submitted, Icarus, 2013) posit that one mode is made up of cloud particles that have diffused upwards from the main sulfuric acid cloud deck below, while the other mode is generated in situ by nucleation of sulfuric acid droplets on meteoric dust. They also propose that the observed variability in the UH is caused in part by vertical transient winds. They test this hypothesis by simulating a column of the Venus atmosphere from 40 to 100 km above the surface using a model based upon the Community Aerosol and Radiation Model for Atmospheres (CARMA). In this work, we significantly extend the analysis using the new more detailed SOIR/VeRa VEx temperature profiles which better constrain the observed strong CO2 15-micron cooling emission and 4.3-μm near-IR heating in Venus' atmosphere (and consistent with Venus Thermospheric General Circulation Model (VTGCM) simulations of Brecht et al. (2011)). We discuss our new results in context of the recent VEx observations (Wilquet et al., Icarus 217, 2012) with an intercomparison with the PVO data. We will also discuss similarities and differences arising from the PVO and VEx epochs where they exist. Additionally we report on our efforts self-consistently applying the VTGCM to constrain the degree to which effects due to vertical transient wind simulations can establish variability timescales and number density profiles that match VEx observations.

  5. Retrieval of Aerosol Parameters from Continuous H24 Lidar-Ceilometer Measurements

    NASA Astrophysics Data System (ADS)

    Dionisi, D.; Barnaba, F.; Costabile, F.; Di Liberto, L.; Gobbi, G. P.; Wille, H.

    2016-06-01

    Ceilometer technology is increasingly applied to the monitoring and the characterization of tropospheric aerosols. In this work, a method to estimate some key aerosol parameters (extinction coefficient, surface area concentration and volume concentration) from ceilometer measurements is presented. A numerical model has been set up to derive a mean functional relationships between backscatter and the above mentioned parameters based on a large set of simulated aerosol optical properties. A good agreement was found between the modeled backscatter and extinction coefficients and the ones measured by the EARLINET Raman lidars. The developed methodology has then been applied to the measurements acquired by a prototype Polarization Lidar-Ceilometer (PLC). This PLC instrument was developed within the EC- LIFE+ project "DIAPASON" as an upgrade of the commercial, single-channel Jenoptik CHM15k system. The PLC run continuously (h24) close to Rome (Italy) for a whole year (2013-2014). Retrievals of the aerosol backscatter coefficient at 1064 nm and of the relevant aerosol properties were performed using the proposed methodology. This information, coupled to some key aerosol type identification made possible by the depolarization channel, allowed a year-round characterization of the aerosol field at this site. Examples are given to show how this technology coupled to appropriate data inversion methods is potentially useful in the operational monitoring of parameters of air quality and meteorological interest.

  6. NOAA backscatter studies

    NASA Technical Reports Server (NTRS)

    Post, Madison J.

    1991-01-01

    In the past year, NOAA has measured and analyzed another year's worth of backscatter over Boulder, CO. The average profile was computed from 80 satellite observations of backscatter spread throughout the year, using NOAA's CO2 coherent lidar operating at a wavelength of 10.59 microns. The seasonal averages show a familiar trend (highest backscattering in spring, perhaps due to Asian dust or biomass burning, and lowest backscattering in fall). The 1990 average profile was not significantly different from the 1988 or 1989 profiles, except that it displays a slight increase in the upper troposphere, perhaps due to the Redoubt Volcano. The NOAA's backscatter processing program (BETA) was refined to enable the calculation of gaseous absorption effects based on rawinsonde measurements, as well as using atmospheric models. NOAA participated in two intercomparisons of aerosol measuring instruments near Boulder, called FRLAB (Front Range Lidar, Aircraft, and Balloon Experiment). Considerable effort was also put into developing a multiagency science proposal to NASA headquarters to work with both JPL and NASA-Marshall to produce an airborne Doppler lidar facility for the DC-8.

  7. A numerical technique for the calculation of cloud optical extinction from lidar

    NASA Technical Reports Server (NTRS)

    Alvarez, J. M.; Vaughan, M. A.

    1993-01-01

    A simple numerical algorithm which calculates optical extinction from cloud lidar data is presented. The method assumes a two-component atmosphere consisting of 'clear air' and cloud particulates. 'Clear air' may consist of either molecules only or a mix of molecules and atmospheric aerosols. For certain clouds, the method may be utilized to provide an estimate of the cloud-atmospheric parameter defined as the ratio of the cloud volume backscatter coefficient to the cloud extinction coefficient divided by the atmospheric volume backscatter coefficient at a given altitude. The cloud-atmospheric parameter may be estimated only from cloud data from which the optical thickness may reliably be used as a constraint on the numerical solution. This constraint provides the additional information necessary to obtain the cloud-atmospheric parameter. Conversely, the method may be applied to obtain cloud extinction and optical thickness from lidar cloud soundings if an estimate of the cloud-atmospheric parameter is available.

  8. LASE measurements of aerosols and water vapor during TARFOX

    NASA Technical Reports Server (NTRS)

    Ferrare, Richard A.; Ismail, Syed; Browell, Edward V.; Brackett, Vincent G.; Kooi, Susan A.; Clayton, Marian B.; Melfi, Harvey; Whiteman, David N.; Schwenner, Geary; Evans, Keith D.; Hobbs, Peter V.; Veefkind, J. Pepijn; Russell, Philip B.; Livingston, John M.; Hignett, Philip; Holben, Brent N.; Remer, Lorraine A.

    1998-01-01

    The TARFOX (Tropospheric Aerosol Radiative Forcing Observational Experiment) intensive field campaign was designed to reduce uncertainties in estimates of the effects of anthropogenic aerosols on climate by measuring direct radiative effects and the optical, physical, and chemical properties of aerosols [1]. TARFOX was conducted off the East Coast of the United States between July 10-31, 1996. Ground, aircraft, and satellite-based sensors measured the sensitivity of radiative fields at various atmospheric levels to aerosol optical properties (i.e., optical thickness, phase function, single-scattering albedo) and to the vertical profile of aerosols. The LASE (Lidar Atmospheric Sensing Experiment) instrument, which was flown on the NASA ER-2 aircraft, measured vertical profiles of total scattering ratio and water vapor during a series of 9 flights. These profiles were used in real-time to help direct the other aircraft to the appropriate altitudes for intensive sampling of aerosol layers. We have subsequently used the LASE aerosol data to derive aerosol backscattering and extinction profiles. Using these aerosol extinction profiles, we derived estimates of aerosol optical thickness (AOT) and compared these with measurements of AOT from both ground and airborne sun photometers and derived from the ATSR-2 (Along Track and Scanning Radiometer 2) sensor on ERS-2 (European Remote Sensing Satellite-2). We also used the water vapor mixing ratio profiles measured simultaneously by LASE to derive precipitable water vapor and compare these to ground based measurements.

  9. Optical and physical properties of stratospheric aerosols from balloon measurements in the visible and near-infrared domains. II. Comparison of extinction, reflectance, polarization, and counting measurements

    NASA Astrophysics Data System (ADS)

    Renard, Jean-Baptiste; Berthet, Gwenaël; Robert, Claude; Chartier, Michel; Pirre, Michel; Brogniez, Colette; Herman, Maurice; Verwaerde, Christian; Balois, Jean-Yves; Ovarlez, Joëlle; Ovarlez, Henri; Crespin, Jacques; Deshler, Terry

    2002-12-01

    The physical properties of stratospheric aerosols can be retrieved from optical measurements involving extinction, radiance, polarization, and counting. We present here the results of measurements from the balloonborne instruments AMON, SALOMON, and RADIBAL, and from the French Laboratoire de Météorologie Dynamique and the University of Wyoming balloonborne particle counters. A cross comparison of the measurements was made for observations of background aerosols conducted during the polar winters of February 1997 and January-February 2000 for various altitudes from 13 to 19 km. On the one hand, the effective radius and the total amount of background aerosols derived from the various sets of data are similar and are in agreement with pre-Pinatubo values. On the other hand, strong discrepancies occur in the shapes of the bimodal size distributions obtained from analysis of the raw measurements of the various instruments. It seems then that the log-normal assumption cannot fully reproduce the size distribution of background aerosols. The effect of the presence of particular aerosols on the measurements is discussed, and a new strategy for observations is proposed.

  10. Development of a high-spectral-resolution lidar for continuous observation of aerosols in South America

    NASA Astrophysics Data System (ADS)

    Jin, Yoshitaka; Sugimoto, Nobuo; Nishizawa, Tomoaki; Ristori, Pablo; Papandrea, Sebastian; Otero, Lidia; Quel, Eduardo; Mizuno, Akira

    2016-05-01

    Continuous monitoring of aerosol profiles using lidar is helpful for a quasi-real-time indication of aerosol concentration. For instance, volcanic ash concentration and its height distribution are essential information for plane flights. Depolarization ratio and multi-wavelength measurements are useful for characterizing aerosol types such as volcanic ash, smoke, dust, sea-salt, and air pollution aerosols. High spectral resolution lidar (HSRL) and Raman scattering lidar can contribute to such aerosol characterization significantly since extinction coefficients can be measured independently from backscattering coefficients. In particular, HSRL can measure aerosol extinction during daytime and nighttime with a high sensitivity. We developed an HSRL with the iodine filter method for continuous observation of aerosols at 532nm in the northern region of Argentina in the framework of the South American Environmental Atmospheric Risk Management Network (SAVER.Net)/SATREPS project. The laser wavelength of the HSRL was controlled by a feedback system to tune the laser wavelength to the center of an iodine absorption line. The stability of the laser wavelength with the system satisfied the requirement showing very small systematic errors in the retrieval of extinction and backscatter.

  11. A Chronology of Annual-Mean Effective Radii of Stratospheric Aerosols from Volcanic Eruptions During the Twentieth Century as Derived From Ground-based Spectral Extinction Measurements

    NASA Technical Reports Server (NTRS)

    Strothers, Richard B.; Hansen, James E. (Technical Monitor)

    2001-01-01

    Stratospheric extinction can be derived from ground-based spectral photometric observations of the Sun and other stars (as well as from satellite and aircraft measurements, available since 1979), and is found to increase after large volcanic eruptions. This increased extinction shows a characteristic wavelength dependence that gives information about the chemical composition and the effective (or area weighted mean) radius of the particles responsible for it. Known to be tiny aerosols constituted of sulfuric acid in a water solution, the stratospheric particles at midlatitudes exhibit a remarkable uniformity of their column-averaged effective radii r(sub eff) in the first few months after the eruption. Considering the seven largest eruptions of the twentieth century, r(sub eff) at this phase of peak aerosol abundance is approx. 0.3 micrometers in all cases. A year later, r(sub eff) either has remained about the same size (almost certainly in the case of the Katmai eruption of 1912) or has increased to approx. 0.5 micrometers (definitely so for the Pinatubo eruption of 1991). The reasons for this divergence in aerosol growth are unknown.

  12. Initial assessment of space-based lidar CALIOP aerosol and cloud layer structures through inter-comparison with a ground-based back-scattering lidar and CloudSat

    NASA Astrophysics Data System (ADS)

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

    2009-03-01

    This study presents results of the intercomparison of aerosol/cloud top and bottom heights obtained from a space-borne active sensor Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) onboard CALIPSO, and the Cloud Profiling Radar (CPR) onboard CloudSat, and the space-borne passive sensor Moderate Resolution Imaging Spectroradiometer (MODIS) onboard Aqua, and ground-based 2-wavelenght polarization lidar system (532 and 1064 nm) at Seoul National University (SNU), Seoul, South Korea. 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 both under cloud-free conditions and in cases of multiple aerosol layers underlying semi-transparent cirrus clouds. Simultaneous space-borne CALIOP, CPR 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, especially for thick opaque clouds. The aerosol extinction profiles from both lidars show good agreement for aerosols within the planetary boundary layer under cloud-free conditions and for the night-time CALIOP flight.

  13. Aerosols

    Atmospheric Science Data Center

    2013-04-17

    ... article title:  Aerosols over Central and Eastern Europe     View Larger Image ... last weeks of March 2003, widespread aerosol pollution over Europe was detected by several satellite-borne instruments. The Multi-angle ...

  14. Lidar Observations of Tropospheric Aerosols Over Northeastern South Africa During the ARREX and SAFARI-2000 Dry Season Experiments

    NASA Technical Reports Server (NTRS)

    Campbell, James R.; Welton, Ellsworth J.; Spinhirne, James D.; Ji, Qiang; Tsay, Si-Chee; Piketh, Stuart J.; Barenbrug, Marguerite; Holben, Brent; Starr, David OC. (Technical Monitor)

    2002-01-01

    During the ARREX-1999 and SAFARI-2000 Dry Season experiments a micropulse lidar (523 nm) instrument was operated at the Skukuza Airport in northeastern South Africa. The Mar was collocated with a diverse array of passive radiometric equipment. For SAFARI-2000 the processed Mar data yields a daytime time-series of layer mean/derived aerosol optical properties, including extinction-to-backscatter ratios and vertical extinction cross-section profile. Combined with 523 run aerosol optical depth and spectral Angstrom exponent calculations from available CIMEL sun-photometer data and normalized broadband flux measurements the temporal evolution of the near surface aerosol layer optical properties is analyzed for climatological trends. For the densest smoke/haze events the extinction-to-backscatter ratio is found to be between 60-80/sr, and corresponding Angstrom exponent calculations near and above 1.75. The optical characteristics of an evolving smoke event from SAFARI-2000 are extensively detailed. The advecting smoke was embedded within two distinct stratified thermodynamic layers, causing the particulate mass to advect over the instrument array in an incoherent manner on the afternoon of its occurrence. Surface broadband flux forcing due to the smoke is calculated, as is the evolution in the vertical aerosol extinction profile as measured by the Han Finally, observations of persistent elevated aerosol during ARREX-1999 are presented and discussed. The lack of corroborating observations the following year makes these observation; both unique and noteworthy in the scope of regional aerosol transport over southern Africa.

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

    NASA Technical Reports Server (NTRS)

    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

    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.

  16. Three-dimensional dust aerosol distribution and extinction climatology over northern Africa simulated with the ALADIN numerical prediction model from 2006 to 2010

    NASA Astrophysics Data System (ADS)

    Mokhtari, M.; Tulet, P.; Fischer, C.; Bouteloup, Y.; Bouyssel, F.; Brachemi, O.

    2015-08-01

    The seasonal cycle and optical properties of mineral dust aerosols in northern Africa were simulated for the period from 2006 to 2010 using the numerical atmospheric model ALADIN (Aire Limitée Adaptation dynamique Développement InterNational) coupled to the surface scheme SURFEX (SURFace EXternalisée). The particularity of the simulations is that the major physical processes responsible for dust emission and transport, as well as radiative effects, are taken into account on short timescales and at mesoscale resolution. The aim of these simulations is to quantify the dust emission and deposition, locate the major areas of dust emission and establish a climatology of aerosol optical properties in northern Africa. The mean monthly aerosol optical thickness (AOT) simulated by ALADIN is compared with the AOTs derived from the standard Dark Target (DT) and Deep Blue (DB) algorithms of the Aqua-MODIS (MODerate resolution Imaging Spectroradiometer) products over northern Africa and with a set of sun photometer measurements located at Banizoumbou, Cinzana, Soroa, Mbour and Cape Verde. The vertical distribution of dust aerosol represented by extinction profiles is also analysed using CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) observations. The annual dust emission simulated by ALADIN over northern Africa is 878 Tg year-1. The Bodélé Depression appears to be the main area of dust emission in northern Africa, with an average estimate of about 21.6 Tg year-1. The simulated AOTs are in good agreement with satellite and sun photometer observations. The positions of the maxima of the modelled AOTs over northern Africa match the observed positions, and the ALADIN simulations satisfactorily reproduce the various dust events over the 2006-2010 period. The AOT climatology proposed in this paper provides a solid database of optical properties and consolidates the existing climatology over this region derived from satellites, the AERONET network and regional climate

  17. CALIPSO-Inferred Aerosol Direct Radiative Effects: Bias Estimates Using Ground-Based Raman Lidars

    NASA Technical Reports Server (NTRS)

    Thorsen, Tyler; Fu, Qiang

    2015-01-01

    Observational constraints on the change in the radiative energy budget caused by the presence of aerosols, i.e. the aerosol direct radiative effect (DRE), have recently been made using observations from the Cloud- Aerosol Lidar and Infrared Pathfinder Satellite (CALIPSO). CALIPSO observations have the potential to provide improved global estimates of aerosol DRE compared to passive sensor-derived estimates due to CALIPSO's ability to perform vertically-resolved aerosol retrievals over all surface types and over cloud. In this study we estimate the uncertainties in CALIPSO-inferred aerosol DRE using multiple years of observations from the Atmospheric Radiation Measurement (ARM) program's Raman lidars (RL) at mid-latitude and tropical sites. Examined are assumptions about the ratio of extinction-to-backscatter (i.e. the lidar ratio) made by the CALIPSO retrievals, which are needed to retrieve the aerosol extinction profile. The lidar ratio is shown to introduce minimal error in the mean aerosol DRE at the top-of-atmosphere and surface. It is also shown that CALIPSO is unable to detect all radiatively-significant aerosol, resulting in an underestimate in the magnitude of the aerosol DRE by 30â€"50%. Therefore, global estimates of the aerosol DRE inferred from CALIPSO observations are likely too weak.

  18. CALIPSO-Inferred Aerosol Direct Radiative Effects: Bias Estimates Using Ground-Based Raman Lidars

    NASA Technical Reports Server (NTRS)

    Thorsen, Tyler; Fu, Qiang

    2016-01-01

    Observational constraints on the change in the radiative energy budget caused by the presence of aerosols, i.e. the aerosol direct radiative effect (DRE), have recently been made using observations from the Cloud- Aerosol Lidar and Infrared Pathfinder Satellite (CALIPSO). CALIPSO observations have the potential to provide improved global estimates of aerosol DRE compared to passive sensor-derived estimates due to CALIPSO's ability to perform vertically-resolved aerosol retrievals over all surface types and over cloud. In this study we estimate the uncertainties in CALIPSO-inferred aerosol DRE using multiple years of observations from the Atmospheric Radiation Measurement (ARM) program's Raman lidars (RL) at midlatitude and tropical sites. Examined are assumptions about the ratio of extinction-to-backscatter (i.e. the lidar ratio) made by the CALIPSO retrievals, which are needed to retrieve the aerosol extinction profile. The lidar ratio is shown to introduce minimal error in the mean aerosol DRE at the top-of-atmosphere and surface. It is also shown that CALIPSO is unable to detect all radiatively-significant aerosol, resulting in an underestimate in the magnitude of the aerosol DRE by 30-50%. Therefore, global estimates of the aerosol DRE inferred from CALIPSO observations are likely too weak.

  19. GLObal Backscatter Experiment (GLOBE) Pacific survey mission

    NASA Technical Reports Server (NTRS)

    Bowdle, David A.; Rothermel, Jeffry; Arnold, James E.; Williams, Steven F.

    1991-01-01

    NASA conducted the GLObal Backscatter Experiment (GLOBE) Survey Mission over the near coastal and remote Pacific Ocean during 6 to 30 Nov. 1989 (GLOBE 1) and 13 May to 5 Jun. 1990 (GLOBE 2). These missions studied the optical, physical, and chemical properties of atmospheric aerosols. Particular emphasis was given to the magnitude and spatial variability of aerosol backscatter coefficients at mid-infrared wavelengths, and to the remote middle and upper troposphere, where these aerosol properties are poorly understood. Survey instruments were selected to provide either direct beta measurements at the key wavelengths, empirical links with long term or global scale aerosol climatologies, or aerosol microphysics data required to model any of these quantities. The survey deployment included both long distance 6 to 8 hour transit flights and detailed 4 to 6 hour local flights. Several general features were observed from preliminary Survey data analyses. Validation and intercomparison results have shown good agreement, usually better than a factor of two. Atmospheric aerosols frequently exhibited a three layer vertical structure, with (1) high and fairly uniform backscatter in the shallow cloud capped marine boundary layer; (2) moderate and highly variable backscatter in a deeper overlaying cloud pumped layer; and (3) low, regionally uniform, but seasonally and latitudinally variable backscatter in the middle and upper troposphere. The survey missions represent two isolated snapshots of a small portion of the global aerosol system. Consequently, Survey results can best be understood by synthesizing them with the more comprehensive GLOBE data base, which is being compiled at NASA-Marshall.

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

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

    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.

  1. Aerosol and Cloud Interaction Observed From High Spectral Resolution Lidar Data

    NASA Technical Reports Server (NTRS)

    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

    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

  2. Coupling Satellite and Ground-Based Instruments to Map Climate Forcing by Anthropogenic Aerosol

    NASA Technical Reports Server (NTRS)

    Charlson, Robert J.; Anderson, Theodore L.; Hostetler, Chris (Technical Monitor)

    2000-01-01

    Climate forcing by anthropogenic aerosols is a significant but highly uncertain factor in global climate change. Only satellites can offer the global coverage essential to reducing this uncertainty; however, satellite measurements must be coupled with correlative, in situ measurements both to constrain the aerosol optical properties required in satellite retrieval algorithms and to provide chemical identification of aerosol sources. This grant funded the third year of a three-year project which seeks to develop methodologies for combining spaceborne lidar with in-situ aerosol data sets to improve estimates of direct aerosol climate forcing. Progress under this one-year grant consisted in analysis and publication of field studies using a new in-situ capability for measuring aerosol 180 deg backscatter and the extinction-to-backscatter ratio. This new measurement capacity allows definitive lidar/in-situ comparisons and improves our ability to interpret lidar data in terms of climatically relevant quantities such as the extinction coefficient and optical depth. Analyzed data consisted of measurements made along the coast of Washington State, in Central Illinois, over the Indian Ocean, and in the Central Pacific. Thus, this research, combined with previous measurements by others, is rapidly building toward a global data set of extinction-to-backscatter ratio for key aerosol types. Such information will be critical to interpreting lidar data from the upcoming PICASSO-CENA, or P-C, satellite mission. Another aspect of this project is to investigate innovative ways to couple the lidar-satellite signal with target in-situ measurements toward a direct determination of aerosol forcing. This aspect is progressing in collaboration with NASA Langley's P-C lidar simulator.

  3. Coupling Satellite and Ground-Based Instruments to Map Climate Forcing by Anthropogenic Aerosols

    NASA Technical Reports Server (NTRS)

    Charlson, Robert J.; Anderson, Theodore L.; Hostetler, Chris (Technical Monitor)

    2000-01-01

    Climate forcing by anthropogenic aerosols is a significant but highly uncertain factor in global climate change. Only satellites can offer the global coverage essential to reducing this uncertainty; however, satellite measurements must be coupled with correlative, in situ measurements both to constrain the aerosol optical properties required in satellite retrieval algorithms and to provide chemical identification of aerosol sources. This grant funded the first two years of a three-year project which seeks to develop methodologies for combining spaceborne lidar with in-situ aerosol data sets to improve estimates of direct aerosol climate forcing. Progress under this two-year grant consisted in the development and deployment of a new in-situ capability for measuring aerosol 180' backscatter and the extinction-to-backscatter ratio. This new measurement capacity allows definitive lidar/in-situ comparisons and improves our ability to interpret lidar data in terms of climatically relevant quantities such as the extinction coefficient and optical depth. Measurements were made along the coast of Washington State, in Central Illinois, over the Indian Ocean, and in the Central Pacific. Thus, this research, combined with previous measurements by others, is rapidly building toward a global data set of extinction-to-backscatter ratio for key aerosol types. Such information will be critical to interpreting lidar data from the upcoming PICASSO-CENA, or P-C, satellite mission. Another aspect of this project is to investigate innovative ways to couple the lidar-satellite signal with targeted in-situ measurements toward a direct determination of aerosol forcing. This aspect is progressing in collaboration with NASA Langley's P-C lidar simulator and radiative transfer modeling by the University of Lille, France.

  4. Shortwave Radiative Fluxes, Solar-Beam Transmissions, and Aerosol Properties: TARFOX and ACE-2 Find More Absorption from Flux Radiometry than from Other Measurements

    NASA Technical Reports Server (NTRS)

    Russell, Philip B.; Redemann, J.; Schmid, B.; Livingston, J. M.; Bergstrom, R. W.; Ramirez, S. A.; Hipskind, R. Stephen (Technical Monitor)

    2001-01-01

    The Tropospheric Aerosol Radiative Forcing Observational Experiment (TARFOX) and the Second Aerosol Characterization Experiment (ACE-2) made simultaneous measurements of shortwave radiative fluxes, solar-beam transmissions, and the aerosols affecting those fluxes and transmissions. Besides the measured fluxes and transmissions, other obtained properties include aerosol scattering and absorption measured in situ at the surface and aloft; aerosol single scattering albedo retrieved from skylight radiances; and aerosol complex refractive index derived by combining profiles of backscatter, extinction, and size distribution. These measurements of North Atlantic boundary layer aerosols impacted by anthropogenic pollution revealed the following characteristic results: (1) Better agreement among different types of remote measurements of aerosols (e.g., optical depth, extinction, and backscattering from sunphotometers, satellites, and lidars) than between remote and in situ measurements; 2) More extinction derived from transmission measurements than from in situ measurements; (3) Larger aerosol absorption inferred from flux radiometry than from other measurements. When the measured relationships between downwelling flux and optical depth (or beam transmission) are used to derive best-fit single scattering albedos for the polluted boundary layer aerosol, both TARFOX and ACE-2 yield midvisible values of 0.90 +/- 0.04. The other techniques give larger single scattering albedos (i.e. less absorption) for the polluted boundary layer, with a typical result of 0.95 +/- 0.04. Although the flux-based results have the virtue of describing the column aerosol unperturbed by sampling, they are subject to questions about representativeness and other uncertainties (e.g., unknown gas absorption). Current uncertainties in aerosol single scattering albedo are large in terms of climate effects. They also have an important influence on aerosol optical depths retrieved from satellite radiances

  5. Atmospheric Backscatter Model Development for CO Sub 2 Wavelengths

    NASA Technical Reports Server (NTRS)

    Deepak, A.; Kent, G.; Yue, G. K.

    1982-01-01

    The results of investigations into the problems of modeling atmospheric backscatter from aerosols, in the lowest 20 km of the atmosphere, at CO2 wavelengths are presented, along with a summary of the relevant aerosol characteristics and their variability, and a discussion of the measurement techniques and errors involved. The different methods of calculating the aerosol backscattering function, both from measured aerosol characteristics and from optical measurements made at other wavelengths, are discussed in detail, and limits are placed on the accuracy of these methods. The effects of changing atmospheric humidity and temperature on the backscatter are analyzed and related to the actual atmosphere. Finally, the results of modeling CO2 backscatter in the atmosphere are presented and the variation with height and geographic location discussed, and limits placed on the magnitude of the backscattering function. Conclusions regarding modeling techniques and modeled atmospheric backscatter values are presented in tabular form.

  6. Evaluation of the effects of Mount Pinatubo aerosol on differential absorption lidar measurements of stratospheric ozone

    SciTech Connect

    Steinbrecht, W.; Carswell, A.I.

    1995-01-01

    Substantially increased aerosol backscattering and extinction after a major volcanic eruption can lead to errors in differential absorption lidar (DIAL) measurements of stratospheric ozone. Mie calculations, performed for the wavelengths 308 and 353 nm and based on size distributions measured over Laramie, Wyoming (41 deg), were used to assess size and temporal evolution of these errors. In many situations, neglecting the different aerosol backscattering at the absorption and reference wavelengths can lead to relative errors in the ozone concentration larger than 100% for the 308-, 353-nm pair. The error due to neglecting the differential aerosol extinction, however, will rarely exceed 2%. A correction for this differential extinction should only be attempted when high concentrations (greater than 100/cu cm) of small aerosol particles with radii below 0.1 micrometers are present, e.g., shortly after an eruption. A correction for the differential backscatter can be made by using additional lidar measurements at a second reference wavelength or by having general size distribution information on the aerosol. Possible corrections were tested and will usually reduce the error in the ozone concentration considerably. For the 308-, 353-nm pair, both Mie calculations and a comparison with ozone profiles from electrochemical cell sondes show, however, that even after the correction the uncertainty in the ozone concentration within some regions of the strongly enhanced Mt. Pinatubo aerosol layer can still be substantial, of the order of 10-50%. Wavelength separation smaller than 40 nm or use of wavelengths shorter than 300 nm will reduce the error. The best solution seems to be the addition of Raman channels. It avoids the large error due to the differential backscatter term.

  7. Aerosol Optical Properties Measured Onboard the Ronald H. Brown During ACE Asia as a Function of Aerosol Chemical Composition and Source Region

    NASA Technical Reports Server (NTRS)

    Quinn, P. K.; Coffman, D. J.; Bates, T. S.; Welton, E. J.; Covert, D. S.; Miller, T. L.; Johnson, J. E.; Maria, S.; Russell, L.; Arimoto, R.

    2004-01-01

    During the ACE Asia intensive field campaign conducted in the spring of 2001 aerosol properties were measured onboard the R/V Ronald H. Brown to study the effects of the Asian aerosol on atmospheric chemistry and climate in downwind regions. Aerosol properties measured in the marine boundary layer included chemical composition; number size distribution; and light scattering, hemispheric backscattering, and absorption coefficients. In addition, optical depth and vertical profiles of aerosol 180 deg backscatter were measured. Aerosol within the ACE Asia study region was found to be a complex mixture resulting from marine, pollution, volcanic, and dust sources. Presented here as a function of air mass source region are the mass fractions of the dominant aerosol chemical components, the fraction of the scattering measured at the surface due to each component, mass scattering efficiencies of the individual components, aerosol scattering and absorption coefficients, single scattering albedo, Angstrom exponents, optical depth, and vertical profiles of aerosol extinction. All results except aerosol optical depth and the vertical profiles of aerosol extinction are reported at a relative humidity of 55 +/- 5%. An over-determined data set was collected so that measured and calculated aerosol properties could be compared, internal consistency in the data set could be assessed, and sources of uncertainty could be identified. By taking into account non-sphericity of the dust aerosol, calculated and measured aerosol mass and scattering coefficients agreed within overall experimental uncertainties. Differences between measured and calculated aerosol absorption coefficients were not within reasonable uncertainty limits, however, and may indicate the inability of Mie theory and the assumption of internally mixed homogeneous spheres to predict absorption by the ACE Asia aerosol. Mass scattering efficiencies of non-sea salt sulfate aerosol, sea salt, submicron particulate organic

  8. Relationships between aerosol optical depth and surface-layer extinction in the central part of the Upper Silesia industrial region over the period of 1983-1994

    NASA Astrophysics Data System (ADS)

    Sztyler, Apoloniusz

    The subject of analysis is the aerosol optical depth (AOD) in the visible part of the solar spectrum (τ) (wavelength λ=0.295-0.695μ m). Calculation of τ-values was based on pyrheliometric observation data performed from 1983 to 1994 at IEIA's station (Katowice-Załęże). This paper examines the dependence of τ and its relation to surface-layer extinction coefficient σ (Koschmider quotient of 3.912 and visibility V) on meteorological and anthropological factors during the observation period. Knowledge of the relationship between columnar aerosol turbidity (which can be expressed by τ) and σ allows a more precise and accurate estimation of the aerosol effect on the radiative composition of climate. This work offers some contributions to solving this problem. Therefore, the relations have been described in the form of mathematical/statistical models of AOD (based on "momentary" and mean seasonal values), in which meteorological (and astronomical) parameters as well as the amount of industry dust emission were used as independent variables to improve exactness and credibility in the models.

  9. Broadband optical extinction measurements and complex refractive indices in the ultraviolet spectral region for biogenic secondary organic aerosol exposed to ammonia

    NASA Astrophysics Data System (ADS)

    Flores, J.; Washenfelder, R. A.; Lee, H.; Segev, L.; Nizkorodov, S.; Brown, S. S.; Rudich, Y.

    2013-12-01

    The interaction between aerosols and sunlight plays an important role in the radiative balance of Earth's atmosphere. Aerosols can both scatter and absorb solar radiation causing surface cooling and heating of the atmosphere. These interactions depend on the optical properties of the aerosols (i.e., complex refractive index). Secondary organic aerosol (SOA) account for a significant fraction of the tropospheric aerosol. However, their chemical, physical, and optical properties, especially as they are processed in the atmosphere (aging), are still poorly understood. In this study, SOA formed by the ozonolysis of various biogenic volatile organic compound (BVOC) precursors (α-pinene, limonene, and α-humulene) were exposed to humid air containing various concentrations of gaseous ammonia which has been shown to cause the biogenic SOA to ';brown' on filters. The extent of absorption of the SOA in the aerosol phase cause by the exposure to gaseous ammonia was measured by a newly developed instrument to measure aerosol extinction as a function of wavelength using Broadband Cavity Enhanced Spectroscopy (BBCES) with a broadband light source. Size-selected measurements of the humid SOA exposed to NH3 for about 1.5 hours were used to derive complex refractive indices (RI) as a function of wavelength in the UV spectral region (from 360 - 420nm). The imaginary part of the refractive index did not exceed 0.05 in the 360 - 420 nm range for SOA formed from the three BVOCs even at high concentrations of NH3 (>1ppm), allowing to place an upper limit of k = 0.05. Furthermore, the small k values are consistent with bulk UV-VIS measurements. However, for the α-pinene SOA, the real part of the RI slightly increased from n = 1.49 to n = 1.55 with negligible spectral dependence. For limonene and α-humulene the real part remind constant within error calculations. Based on these observations, reactive uptake of gaseous ammonia is not expected to significantly affect absorption and

  10. Infrared backscattering

    NASA Technical Reports Server (NTRS)

    Bohren, Craig F.; Nevitt, Timothy J.; Singham, Shermila Brito

    1989-01-01

    All particles in the atmosphere are not spherical. Moreover, the scattering properties of randomly oriented nonspherical particles are not equivalent to those of spherical particles no matter how the term equivalent is defined. This is especially true for scattering in the backward direction and at the infrared wavelengths at which some atmospheric particles have strong absorption bands. Thus calculations based on Mie theory of infrared backscattering by dry or insoluble atmospheric particles are suspect. To support this assertion, it was noted that peaks in laboratory-measured infrared backscattering spectra show appreciable shifts compared with those calculated using Mie theory. One example is ammonium sulfate. Some success was had in modeling backscattering spectra of ammonium sulfate particles using a simple statistical theory called the continuous distribution of ellipsoids (CDE) theory. In this theory, the scattering properties of an ensemble are calculated. Recently a modified version of this theory was applied to measured spectra of scattering by kaolin particles. The particles were platelike, so the probability distribution of ellipsoidal shapes was chosen to reflect this. As with ammonium sulfate, the wavelength of measured peak backscattering is shifted longward of that predicted by Mie theory.

  11. Infrared Extinction Coefficients of Aerosolized Conductive Flake Powders and Flake Suspensions having a Zero-Truncated Poisson Size Distribution

    DTIC Science & Technology

    2012-11-01

    A twin-fluid atomizing nozzle was used to disseminate all materials into a stirred 190 m 3 cylindrical aerosol chamber. After dispersion by the... nozzle and thorough chamber mixing with a low speed fan, spectral aerosol transmittance and concentration were simultaneously measured to obtain spectral...varying concentrations were prepared by stirring and sonicating the powders in ethanol. A twin-fluid atomizing nozzle , consisting of a jet of the

  12. Evaluating the impact of assimilating CALIOP-derived aerosol extinction profiles on a global mass transport model

    NASA Astrophysics Data System (ADS)

    Zhang, Jianglong; Campbell, James R.; Reid, Jeffrey S.; Westphal, Douglas L.; Baker, Nancy L.; Campbell, William F.; Hyer, Edward J.

    2011-07-01

    Coupled two/three-dimensional variational (2D/3DVAR) assimilation of aerosol physical properties retrieved from the Moderate Resolution Imaging Spectroradiometer (MODIS), Multi-angle Imaging Spectroradiometer (MISR) and Cloud Aerosol Lidar with Orthogonal Polarization (CALIOP) satellite-borne instruments is described for the U. S. Navy Aerosol Analysis and Prediction System (NAAPS) global aerosol mass transport model. Coupled 2D/3DVAR assimilation for NAAPS is evaluated for 48-hr forecast cycles, computed four times daily in six-hour intervals, versus stand-alone 2DVAR assimilation of MODIS and MISR aerosol optical depths (AOD). Both systems are validated against AERONET ground-based sun photometer measurements of AOD. Despite a narrow nadir viewing swath and more than 2700 km of equatorial separation between orbits, satellite lidar data assimilation elicits a positive model response. Improvements in analysis and forecast AOD absolute errors are found over both land and maritime AERONET sites. The primary impact to the model from 3DVAR assimilation is the redistribution of aerosol mass into the boundary layer, though the process is sensitive to parameterization of vertical error correlation lengths.

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

    NASA Technical Reports Server (NTRS)

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

    2007-01-01

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

  14. Accuracy Remote-Sensing of Aerosol Spatial Distribution in the Lower Troposphere by Twin Scanning Lidars

    NASA Astrophysics Data System (ADS)

    Gao, F.; Hua, D.; Li, Y.; Li, W.; Wang, L.

    2015-12-01

    Aerosols in the lower troposphere play an important role in the absorption and scattering of atmospheric radiation, the forming of precipitation and the circulation of chemistry. Due to the influence of solar heating at the surface, the aerosol distribution is inhomogeneous and variation with time. Lidar is proven to be a powerful tool in the application of remote sensing of atmospheric properties (Klett 1981). However, the existing of overlap function in lidar equation limits the fine detection of aerosol optical properties in the lower troposphere by vertical measurement, either by Raman lidar (Whiteman 2003) or by high spectral resolution lidar (Imaki 2005). Although the multi-angle method can succeed the aerosol measurement from the ground, the homogeneous atmospheric is needed (Pahlow 2004). Aiming to detect the inhomogeneous aerosols in the lower troposphere and to retrieve the aerosol extinction and backscatter coefficients in the lidar equation, a novel method for accuracy remote-sensing of aerosol properties based on twin scanning lidars has been proposed. In order to realize the fine detection of the aerosol spatial distribution from the ground to the height of interest of atmosphere, the scanning lidar is utilized as the remote sensing tool combined with the cross scanning by the twin systems, which makes the exact solutions of those two unknown parameters retrievable. Figure shows the detection method for aerosol spatial distribution using twin scanning lidars. As two lidar equations are provided simultaneously, the aerosol extinction and backscatter coefficients are retrievable. Moreover, by selecting the transmitting laser wavelength, the presented method can realize the fine detection of aerosol at any spectrum, even the theoretical and technical analysis of the aerosol characteristics by applying multi-spectra.

  15. Near Real Time Vertical Profiles of Clouds and Aerosols from the Cloud-Aerosol Transport System (CATS) on the International Space Station

    NASA Astrophysics Data System (ADS)

    Yorks, J. E.; McGill, M. J.; Nowottnick, E. P.

    2015-12-01

    Plumes from hazardous events, such as ash from volcanic eruptions and smoke from wildfires, can have a profound impact on the climate system, human health and the economy. Global aerosol transport models are very useful for tracking hazardous plumes and predicting the transport of these plumes. However aerosol vertical distributions and optical properties are a major weakness of global aerosol transport models, yet a key component of tracking and forecasting smoke and ash. The Cloud-Aerosol Transport System (CATS) is an elastic backscatter lidar designed to provide vertical profiles of clouds and aerosols while also demonstrating new in-space technologies for future Earth Science missions. CATS has been operating on the Japanese Experiment Module - Exposed Facility (JEM-EF) of the International Space Station (ISS) since early February 2015. The ISS orbit provides more comprehensive coverage of the tropics and mid-latitudes than sun-synchronous orbiting sensors, with nearly a three-day repeat cycle. The ISS orbit also provides CATS with excellent coverage over the primary aerosol transport tracks, mid-latitude storm tracks, and tropical convection. Data from CATS is used to derive properties of clouds and aerosols including: layer height, layer thickness, backscatter, optical depth, extinction, and depolarization-based discrimination of particle type. The measurements of atmospheric clouds and aerosols provided by the CATS payload have demonstrated several science benefits. CATS provides near-real-time observations of cloud and aerosol vertical distributions that can be used as inputs to global models. The infrastructure of the ISS allows CATS data to be captured, transmitted, and received at the CATS ground station within several minutes of data collection. The CATS backscatter and vertical feature mask are part of a customized near real time (NRT) product that the CATS processing team produces within 6 hours of collection. The continuous near real time CATS data

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

    NASA Astrophysics Data System (ADS)

    Stachlewska, I. S.; Ritter, C.

    2010-03-01

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

  17. Condensation nuclei and aerosol-scattering extinction measurements at Mauna Loa Observatory: 1974-1985. Data report

    SciTech Connect

    Massey, D.M.; Quakenbush, T.K.; Bodhaine, B.A.

    1987-07-01

    The observatory at Mauna Loa, Hawaii measures the characteristics of surface aerosols under background conditions. The instruments provide data that are representative of the background-aerosol climatology at Mauna Loa. These data can also be used to identify potential local contamination periods. The nephelometer's light-scattering measurements show an annual cycle: a maximum in April and a minimum in November, with a variation of a factor of 5.5. The Condensation Nucleus (CN) counter shows a much smaller annual cycle: a maximum in September and a minimum in March, with a variation of a factor of 1.5. A local decrease in CN concentration occurs in August. The Angstrom exponent minimum occurs in May. This indicates larger aerosol particles within the month as compared with the remainder of the year.

  18. CU AMAX-DOAS applications in cloud-free and cloudy atmospheres: innovative Scattered Sun Light observations of trace gases and aerosol extinction

    NASA Astrophysics Data System (ADS)

    Volkamer, R.; Baidar, S.; Coburn, S.; Dix, B. K.; Oetjen, H.; Ortega, I.; Sinreich, R.; Atmospeclab

    2011-12-01

    An innovative airborne scanning multi-axis differential optical absorption spectroscopy (CU AMAX-DOAS) instrument has been developed at the University of Colorado, Boulder. The instrument collects scattered sunlight spectra in a sequence of discrete viewing angles, and employs the DOAS method (inherently calibrated, and selective) to simultaneously retrieve multiple trace gases, e.g., nitrogen dioxide (NO2), nitrous acid (HONO), formaldehyde (HCHO), glyoxal (CHOCHO), bromine oxide (BrO), iodine oxide (IO), chlorine dioxide (OClO), water vapor (H2O), and oxygen dimers (O4, at 360nm, 477nm, and 632nm) differential slant column densities (dSCD). Vertical profiles of these gases and multi-spectral aerosol extinction are inferred by combining Monte-Carlo Radiative Transfer Modelling (RTM) and optimal estimation techniques to construct a model atmosphere that can in principle represent 3D clouds and aerosols. The atmospheric state of this model atmosphere is constrained by observations of O4 dSCDs, Raman Scattering Probability (RSP), and intensity ratios, i.e., quantities that depend solely on relative intensity changes, without need for a direct sun view, or absolute radiance calibration. We show results from ongoing validation efforts (NOAA TwinOtter aircraft during CalNex and CARES), and demonstrate vertical profile retrievals (NSF/NCAR GV over the tropical Pacific Ocean) in both cloud-free and cloudy atmospheres.

  19. Measured Infrared Absorption and Extinction Cross Sections for a Variety of Chemically and Biologically Derived Aerosol Simulants

    DTIC Science & Technology

    2004-06-01

    Aerosols considered are categorized as biological, chemical, and inorganic in origin, i.e., bacillus subtilis endospores, dimethicone silicone oil...achieved. The materials considered for this study include dimethicone silicone oil (SF-96 grade 50), bacillus subtilis endospores (BG), and Kaolin

  20. Volcanic Aerosols from Satellites: Current and Emerging Capabilities

    NASA Astrophysics Data System (ADS)

    Bhartia, P. K.; McCormick, M. P.; Loughman, R. P.

    2015-12-01

    There are 5 instruments currently operating in space with capability to measure stratospheric aerosols. Two of these are lidar backscatter instruments (CALIOP & ISS/CATS) that provide high vertical resolution, day/night coverage, and polarization information to separate ice clouds from sulfate aerosols. Two are limb scattering instruments (OSIRIS & OMPS-LP) with high sensitivity to aerosols and provide extensive spatial coverage of the sunlit globe. And a Canadian solar occultation instrument (ACE-MAESTRO) measures aerosol extinction twice per orbit. Next year we are expecting the launch of the SAGE III instrument on ISS with capability to measure aerosol extinction and Angstrom Exponent (AE) at multiple wavelengths by solar and lunar occultation techniques. It also has limb scattering capability to provide spatial coverage between solar occultations. The 51.6˚ inclination of the ISS orbit will allow SAGE III to measure aerosol scattering across the gobe for a wide range of scattering angles. Therefore, ISS SAGE III has the capability to provide vertically resolved information about a wide variety of aerosol properties, potentially including aerosol extinction, size distribution, refractive index, and particle shape parameters, similar to the one provided by the ground-based almucantar technique. In our talk we will focus primarily on the synergy between the OMPS LP instrument that has been flying on the Suomi NPP satellite since October 2011 and ISS SAGE III. We will show how these measurements can be combined together to capture spatial and temporal evolution of aerosols and ozone in large volcanic plumes to validate models and to support field campaigns.

  1. Optical characterization of continental and biomass-burning aerosols over Bozeman, Montana: A case study of the aerosol direct effect

    NASA Astrophysics Data System (ADS)

    Nehrir, Amin R.; Repasky, Kevin S.; Reagan, John A.; Carlsten, John L.

    2011-11-01

    Atmospheric aerosol optical properties were observed from 21 to 27 September 2009 over Bozeman, Montana, during a transitional period in which background polluted rural continental aerosols and well-aged biomass-burning aerosols were the dominant aerosol types of extremely fresh biomass-burning aerosols resulting from forest fires burning in the northwestern United States and Canada. Aerosol optical properties and relative humidity profiles were retrieved using an eye-safe micropulse water vapor differential absorption lidar (DIAL) (MP-DIAL), a single-channel backscatter lidar, a CIMEL solar radiometer as part of the Aerosol Robotic Network (AERONET), a ground-based integrating nephelometer, and aerosol products from Moderate Resolution Imaging Spectroradiometer (MODIS) Terra and Aqua. Aerosol optical depths (AODs) measured during the case study ranged between 0.03 and 0.17 (0.015 and 0.075) at 532 nm (830 nm) as episodic combinations of fresh and aged biomass-burning aerosols dominated the optical depth of the pristinely clean background air. Here, a pristinely clean background refers to very low AOD conditions, not that the aerosol scattering and absorption properties are necessarily representative of a clean aerosol type. Diurnal variability in the aerosol extinction to backscatter ratio (Sa) of the background atmosphere derived from the two lidars, which ranged between 55 and 95 sr (50 and 90 sr) at 532 nm (830 nm), showed good agreement with retrievals from AERONET sun and sky measurements over the same time period but were consistently higher than some aerosol models had predicted. Sa measured during the episodic smoke events ranged on average from 60 to 80 sr (50 to 70 sr) at 532 nm (830 nm) while the very fresh biomass-burning aerosols were shown to exhibit significantly lower Sa ranging between 20 and 40 sr. The shortwave direct radiative forcing that was due to the intrusion of biomass-burning aerosols was calculated to be on average -10 W/m2 and was

  2. HSRL-2 Observations of Aerosol Variability During an Aerosol Build-up Event in Houston and Comparisons With WRF-Chem

    NASA Technical Reports Server (NTRS)

    Burton, Sharon P.; Saide, Pablo; Sawamura, Patricia; Hostetler, Chris; Ferrare, Rich; Scarino, Amy Jo; Berkoff, Tim; Harper, David; Cook, Tony; Rogers, Ray; Carmichael, Greg

    2015-01-01

    The NASA Langley airborne multi-wavelength High Spectral Resolution Lidar (HSRL-2) provides vertical distribution of aerosol optical properties as curtains of aerosol extinction, backscatter and depolarization along the flight track, plus intensive properties that are used to infer aerosol type and external mixing of types. Deployed aboard the NASA Langley King Air on the DISCOVER-AQ field mission in Houston in September 2013, HSRL-2 flew a pattern that included 18 ground sites, repeated four times a day, coordinated with a suite of airborne in situ measurements. The horizontally and vertically resolved curtains of HSRL-2 measurements give an unparalleled view of the spatial and temporal variability of aerosol, which provide broad context for interpreting other measurements and models. Detailed comparisons of aerosol extinction are made with the WRF-Chem chemical transport model along the HSRL-2 flight path. The period from Sept. 11-14 is notable for a large aerosol build-up and persistent smoke layers. We investigate the aerosol properties using the vertically resolved HSRL-2 measurements and aerosol typing analysis plus WRFChem model tracers and back trajectories, and modeling of humidification effects.

  3. Evaluation of Daytime Measurements of Aerosols and Water Vapor made by an Operational Raman Lidar over the Southern Great Plains

    NASA Technical Reports Server (NTRS)

    Ferrare, Richard; Turner, David; Clayton, Marian; Schmid, Beat; Covert, David; Elleman, Robert; Orgren, John; Andrews, Elisabeth; Goldsmith, John E. M.; Jonsson, Hafidi

    2006-01-01

    Raman lidar water vapor and aerosol extinction profiles acquired during the daytime over the Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) site in northern Oklahoma (36.606 N, 97.50 W, 315 m) are evaluated using profiles measured by in situ and remote sensing instruments deployed during the May 2003 Aerosol Intensive Operations Period (IOP). The automated algorithms used to derive these profiles from the Raman lidar data were first modified to reduce the adverse effects associated with a general loss of sensitivity of the Raman lidar since early 2002. The Raman lidar water vapor measurements, which are calibrated to match precipitable water vapor (PWV) derived from coincident microwave radiometer (MWR) measurements were, on average, 5-10% (0.3-0.6 g/m(exp 3) higher than the other measurements. Some of this difference is due to out-of-date line parameters that were subsequently updated in the MWR PWV retrievals. The Raman lidar aerosol extinction measurements were, on average, about 0.03 km(exp -1) higher than aerosol measurements derived from airborne Sun photometer measurements of aerosol optical thickness and in situ measurements of aerosol scattering and absorption. This bias, which was about 50% of the mean aerosol extinction measured during this IOP, decreased to about 10% when aerosol extinction comparisons were restricted to aerosol extinction values larger than 0.15 km(exp -1). The lidar measurements of the aerosol extinction/backscatter ratio and airborne Sun photometer measurements of the aerosol optical thickness were used along with in situ measurements of the aerosol size distribution to retrieve estimates of the aerosol single scattering albedo (omega(sub o)) and the effective complex refractive index. Retrieved values of omega(sub o) ranged from (0.91-0.98) and were in generally good agreement with omega(sub o) derived from airborne in situ measurements of scattering and absorption. Elevated aerosol

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

    NASA Technical Reports Server (NTRS)

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

    2008-01-01

    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.

  5. Concept Design of a Multiwavelength Aerosol Lidar System With Mitigated Diattenuation Effects and Depolarization-Measurement Capability

    NASA Astrophysics Data System (ADS)

    Comerón, Adolfo; Sicard, Michaël; Vidal, Eric; Barragán, Rubén; Muñoz, Constantino; Rodríguez, Alejandro; Tiana-Alsina, Jordi; Rocadenbosch, Francesc; García-Vizcaíno, David

    2016-06-01

    It is known that the retrieval of aerosol extinction and backscatter coefficients from lidar data acquired through so-called total-power channels - intended to measure the backscattered power irrespective of the polarization - can be adversely affected by varying depolarization effects produced by the aerosol under measurement. This effect can be particularly noticeable in advanced multiwavelength systems, where different wavelengths are separated using a system of dichroic beam splitters, because in general the reflection and transmission coefficients of the beam splitters will be different for fields with polarization parallel or perpendicular to the incidence plane. Here we propose a setup for multiwavelength aerosol lidars alleviating diattenuation effects due to changing depolarization conditions while allowing measure linear depolarization.

  6. Atmospheric aerosol monitoring by an elastic Scheimpflug lidar system.

    PubMed

    Mei, Liang; Brydegaard, Mikkel

    2015-11-30

    This work demonstrates a new approach - Scheimpflug lidar - for atmospheric aerosol monitoring. The atmospheric backscattering echo of a high-power continuous-wave laser diode is received by a Newtonian telescope and recorded by a tilted imaging sensor satisfying the Scheimpflug condition. The principles as well as the lidar equation are discussed in details. A Scheimpflug lidar system operating at around 808 nm is developed and employed for continuous atmospheric aerosol monitoring at daytime. Localized emission, atmospheric variation, as well as the changes of cloud height are observed from the recorded lidar signals. The extinction coefficient is retrieved according to the slope method for a homogeneous atmosphere. This work opens up new possibilities of using a compact and robust Scheimpflug lidar system for atmospheric aerosol remote sensing.

  7. Vertical columns of NO2, HONO, HCHO, CHOCHO and aerosol extinction: diurnal and seasonal variations in context of CalNex and CARES

    NASA Astrophysics Data System (ADS)

    Ortega, I.; Coburn, S.; Oetjen, H.; Sinreich, R.; Thalman, R. M.; Waxman, E.; Volkamer, R.

    2011-12-01

    We present results from two ground-based University of Colorado Multi Axis Differential Optical Absorption Spectroscopy (CU-MAX-DOAS) instruments that were deployed during the CALNEX and CARES 2010 field campaigns. Ground based CU-MAX-DOAS measurements were carried out through Dec 2010, and measured vertical column abundances of nitrogen dioxide (NO2), nitrous acid (HONO), formaldehyde (HCHO), glyoxal (CHOCHO), and aerosol extinction, which is determined indirectly from observing the oxygen dimers (O4). The measurements were acquired on the top of Millikan library at Caltech, Pasadena, CA, at the Fontana Arrows site located 60 Km east of Caltech, and for a limited period also downwind of Sacramento at T1 site during CARES. In the South Coast Air Basin, the MAX-DOAS instruments at both sites collected an extended time series of use to test satellites, and atmospheric chemistry models. We determine the state of the planetary boundary layer by comparing the columns observations with in-situ sensors, and place the CALNEX and CARES measurements intensive into seasonal context.

  8. Optical backscatter characteristics of Arctic polar stratospheric clouds

    NASA Technical Reports Server (NTRS)

    Kent, G. S.; Schaffner, S. K.; Poole, L. R.; Mccormick, M. P.; Hunt, W. H.

    1990-01-01

    Airborne lidar measurements have been made of polar stratospheric clouds (PSCs) during the Airborne Arctic Stratospheric Expedition in January-February 1989. These show the existence of a systematic relationship between the backscatter depolarization ratio and the (aerosol + molecular)/molecular backscatter ratio. The data are consistent with a two population PSC particle model.

  9. Aerosol Classification from High Spectral Resolution Lidar Measurements

    NASA Astrophysics Data System (ADS)

    Burton, S. P.; Hair, J. W.; Ferrare, R. A.; Hostetler, C. A.; Kahnert, M.; Vaughan, M. A.; Cook, A. L.; Harper, D. B.; Berkoff, T.; Seaman, S. T.; Collins, J. E., Jr.; Fenn, M. A.; Rogers, R. R.

    2015-12-01

    The NASA Langley airborne High Spectral Resolution Lidars, HSRL-1 and HSRL-2, have acquired large datasets of vertically resolved aerosol extinction, backscatter, and depolarization during >30 airborne field missions since 2006. The lidar measurements of aerosol intensive parameters like lidar ratio and color ratio embed information about intrinsic aerosol properties, and are combined to qualitatively classify HSRL aerosol measurements into aerosol types. Knowledge of aerosol type is important for assessing aerosol radiative forcing, and can provide useful information for source attribution studies. However, atmospheric aerosol is frequently not a single pure type, but instead is a mixture, which affects the optical and radiative properties of the aerosol. We show that aerosol intensive parameters measured by lidar can be understood using mixing rules for cases of external mixing. Beyond coarse classification and mixing between classes, variations in the lidar aerosol intensive parameters provide additional insight into aerosol processes and composition. This is illustrated by depolarization measurements at three wavelengths, 355 nm, 532 nm, and 1064 nm, made by HSRL-2. Particle depolarization ratio is an indicator of non-spherical particles. Three cases each have a significantly different spectral dependence of the depolarization ratio, related to the size of the depolarizing particles. For two dust cases, large non-spherical particles account for the depolarization of the lidar light. The spectral dependence reflects the size distribution of these particles and reveals differences in the transport histories of the two plumes. For a smoke case, the depolarization is inferred to be due to the presence of small coated soot aggregates. Interestingly, the depolarization at 355 nm is similar for this smoke case compared to the dust cases, having potential implications for the upcoming EarthCARE satellite, which will measure particle depolarization ratio only at 355 nm.

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

    NASA Astrophysics Data System (ADS)

    Stachlewska, I. S.; Ritter, C.

    2009-09-01

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

  11. Airborne Lidar Observations of Tropospheric Aerosols during the GLOBE Pacific Circumnavigation Missions of 1989 and 1990

    NASA Technical Reports Server (NTRS)

    Menzies, R.; Tratt, D.

    1995-01-01

    Tropospheric and lower stratospheric aerosol backscatter profiles were obtained with an airborne backscatter lidar during the NASA Globe Backscatter Experiment (GLOBE) missions in November 1989 and May/June 1990.

  12. Systematic Relationships among Background SE U.S. Aerosol Optical, Micro-physical, and Chemical Properties-Development of an Optically-based Aerosol Characterization

    NASA Astrophysics Data System (ADS)

    Sherman, J. P.; Link, M. F.; Zhou, Y.

    2014-12-01

    Remote sensing-based retrievals of aerosol composition require known or assumed relationships between aerosol optical properties and types. Most optically-based aerosol classification schemes apply some combination of the spectral dependence of aerosol light scattering and absorption-using the absorption and either scattering or extinction Angstrom exponents (AAE, SAE and EAE), along with single-scattering albedo (SSA). These schemes can differentiate between such aerosol types as dust, biomass burning, and urban/industrial but no such studies have been conducted in the SE U.S., where a large fraction of the background aerosol is a variable mixture of biogenic SOA, sulfates, and black carbon. In addition, AERONET retrievals of SSA are often highly uncertain due to low AOD in the region during most months. The high-elevation, semi-rural AppalAIR facility at Appalachian State University in Boone, NC (1090m ASL, 36.210N, 81.690W) is home to the only co-located NOAA-ESRL and AERONET monitoring sites in the eastern U.S. Aerosol chemistry measured at AppalAIR is representative of the background SE U.S (Link et al. 2014) Dried aerosol light absorption and dried and humidified aerosol light scattering and hemispheric backscattering at 3 visible wavelengths and 2 particle size cuts (sub-1μm and sub-10μm) are measured continuously. Measurements of size-resolved, non-refractory sub-1μm aerosol composition were made by a co-located AMS during the 2012-2013 summers and 2013 winter. Systematic relationships among aerosol optical, microphysical, and chemical properties were developed to better understand aerosol sources and processes and for use in higher-dimension aerosol classification schemes. The hygroscopic dependence of visible light scattering is sensitive to the ratio of sulfate to organic aerosol(OA), as are SSA and AAE. SAE is a less sensitive indicator of fine-mode aerosol size than hemispheric backscatter fraction (b) and is more sensitive to fine-mode aerosol

  13. Optical properties and cross-sections of biological aerosols

    NASA Astrophysics Data System (ADS)

    Thrush, E.; Brown, D. M.; Salciccioli, N.; Gomes, J.; Brown, A.; Siegrist, K.; Thomas, M. E.; Boggs, N. T.; Carter, C. C.

    2010-04-01

    There is an urgent need to develop standoff sensing of biological agents in aerosolized clouds. In support of the Joint Biological Standoff Detection System (JBSDS) program, lidar systems have been a dominant technology and have shown significant capability in field tests conducted in the Joint Ambient Breeze Tunnel (JABT) at Dugway Proving Ground (DPG). The release of biological agents in the open air is forbidden. Therefore, indirect methods must be developed to determine agent cross-sections in order to validate sensor against biological agents. A method has been developed that begins with laboratory measurements of thin films and liquid suspensions of biological material to obtain the complex index of refraction from the ultraviolet (UV) to the long wave infrared (LWIR). Using that result and the aerosols' particle size distribution as inputs to Mie calculations yields the backscatter and extinction cross-sections as a function of wavelength. Recent efforts to model field measurements from the UV to the IR have been successful. Measurements with aerodynamic and geometric particle sizers show evidence of particle clustering. Backscatter simulations of these aerosols show these clustered particles dominate the aerosol backscatter and depolarization signals. In addition, these large particles create spectral signatures in the backscatter signal due to material absorption. Spectral signatures from the UV to the IR have been observed in simulations of field releases. This method has been demonstrated for a variety of biological simulant materials such as Ovalbumin (OV), Erwinia (EH), Bacillus atrophaeus (BG) and male specific bacteriophage (MS2). These spectral signatures may offer new methods for biological discrimination for both stand-off sensing and point detection systems.

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

    NASA Astrophysics Data System (ADS)

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

    2011-07-01

    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.

  15. Multiple scattering wavelength dependent backscattering of kaolin dust in the IR: Measurements and theory

    NASA Technical Reports Server (NTRS)

    Ben-David, Avishai

    1992-01-01

    Knowing the optical properties of aerosol dust is important for designing electro-optical systems and for modeling the effect on propagation of light in the atmosphere. As CO2 lidar technology becomes more advanced and is used for multiwavelength measurements, information on the wavelength dependent backscattering of aerosol dust particles is required. The volume backscattering coefficient of aerosols in the IR is relatively small. Thus, only a few field measurements of backscattering, usually at only a few wavelengths, are reported in the literature. We present spectral field measurements of backscattering of kaolin dust in the 9-11 micron wavelength range. As the quantity of dust increases, multiple scattering contributes more to the measured backscattered signal. The measurements show the effect of the dust quantity of the spectral backscatter measurements. A simple analytical two stream radiative transfer model is applied to confirm the measurements and to give insight to the multiple scattering spectra of backscattering.

  16. AMALi - the Airborne Mobile Aerosol Lidar for Arctic research

    NASA Astrophysics Data System (ADS)

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

    2010-03-01

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

  17. Lidar beams in opposite directions for quality assessment of Cloud-Aerosol Lidar with Orthogonal Polarization spaceborne measurements.

    PubMed

    Cuesta, Juan; Flamant, Pierre H

    2010-04-20

    We present the "lidar beams in opposite directions" (LIBOD) technique and applications for quality assessment of spaceborne observations made by Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) onboard the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation satellite. LIBOD is applicable to standard total backscatter lidar because it does not require a priori knowledge of the particle extinction-to-backscatter ratio. In this paper, we present (i) an objective assessment of the lidar signal quality and representativity of correlative ground-based lidar and CALIOP measurements only using normalized range-corrected lidar signals and (ii) a numerical filtering and optimization technique for reducing the spurious oscillations induced by noisy signal differentiation as needed for retrieval of particle extinction coefficients and extinction-to-backscatter ratio profiles. Numerical simulations and Monte Carlo tests are conducted for assessing the performance of the LIBOD technique. The applications are illustrated with examples of actual correlative 532 nm lidar profiles from CALIOP and a ground-based lidar deployed in Tamanrasset in the heart of Sahara in 2006 and near Strasbourg, France, in 2007.

  18. Inter-comparison of MAX-DOAS Retrieved Vertical Profiles of Aerosol Extinction, SO2 and NO2 in the Alberta Oil Sands with LIDAR Data and GEM-MACH Air Quality Model.

    NASA Astrophysics Data System (ADS)

    Davis, Zoe; Friess, Udo; Strawbridge, Kevin; Whiteway, James; Aggarwal, Monika; Makar, Paul; Li, Shao-Meng; O'Brien, Jason; Baray, Sabour; Schnitzler, Elijah; Olfert, Jason S.; Osthoff, Hans D.; Lobo, Akshay; McLaren, Robert

    2016-04-01

    Understanding industrial emissions of trace gas pollutants in the Alberta oil sands is essential to maintaining air quality standards and informing public policy. Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) measurements of trace gases can improve knowledge of pollutant levels, vertical distribution and chemical transformation. During an intensive air measurement campaign to study emissions, transport, transformation and deposition of oil sands air pollutants from August to September of 2013, a MAX-DOAS instrument was deployed at a site north of Fort McMurray, Alberta to determine the vertical profiles of aerosol extinction, NO2 and SO2 through retrieval from the MAX-DOAS spectral measurements using an optimal estimation method. The large complement of data collected from multiple instruments deployed during this field campaign provides a unique opportunity to validate and characterize the performance of the MAX-DOAS vertical profile retrievals. Aerosol extinction profiles determined from two Light Detection and Ranging (LIDAR) instruments, one collocated and the other on a Twin Otter aircraft that flew over the site during the study, will be compared to the MAX-DOAS aerosol extinction profile retrievals. Vertical profiles of NO2 and SO2 retrieved from the MAX-DOAS measurements will be further compared with the composite vertical profiles measured from the flights of a second aircraft, the NRC-Convair 580, over the field site during the same measurement period. Finally, the MAX-DOAS retrieved tropospheric vertical column densities (VCDs) of SO2 and NO2 will be compared to the predicted VCDs from Environment and Climate Change Canada's Global Environmental Multi-scale - Modelling Air quality and Chemistry (GEM-MACH) air quality model over the grid cell containing the field site. Emission estimates of SO2 from the major oil mining facility Syncrude Mildred Lake using the MAX-DOAS VCD results, validated through the detailed characterization above

  19. Retrieval of Aerosol Profiles using Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS)

    NASA Astrophysics Data System (ADS)

    Yilmaz, Selami; Frieß, Udo; Apituley, Arnoud; Henzing, Bas; Baars, Holger; Heese, Birgit; Althausen, Dietrich; Adam, Mariana; Putaud, Jean-Philippe; Zieger, Paul; Platt, Ulrich

    2010-05-01

    Multi Axis Differential Absorption Spectroscopy (MAX-DOAS) is a well established measurement technique to derive atmospheric trace gas profiles. Using MAX-DOAS measurements of trace gases with a known vertical profile, like the oxygen-dimer O4, it is possible to retrieve information on atmospheric aerosols. Based on the optimal estimation method, we have developed an algorithm which fits simultaneously measured O4 optical densities and relative intensities at several wavelengths and elevation angles to values simulated by a radiative transfer model. Retrieval parameters are aerosol extinction profile and optical properties such as single scattering albedo, phase function and Angström exponent. In 2008 and 2009 several intercomparison campaigns with established aerosol measurement techniques took place in Cabauw/Netherlands, Melpitz/Germany, Ispra/Italy and Leipzig/Germany, where simultaneous DOAS, lidar, Sun photometer and Nephelometer measurements were performed. Here we present results of the intercomparisons for cloud free conditions. The correlation of the aerosol optical thickness retrieved by the DOAS technique and the Sun photometer shows coefficients of determination from 0.96 to 0.98 and slopes from 0.94 to 1.07. The vertical structure of the DOAS retrieved aerosol extinction profiles compare favourably with the structures seen by the backscatter lidar. However, the vertical spatial development of the boundary layer is reproduced with a lower resolution by the DOAS technique. Strategies for the near real-time retrieval of trace gas profiles, aerosol profiles and optical properties will be discussed as well.

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

    NASA Astrophysics Data System (ADS)

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

    2011-11-01

    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 (3β+2α+1δ) 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 (3β + 2α+1δ) 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

  1. [Characteristics and Parameterization for Atmospheric Extinction Coefficient in Beijing].

    PubMed

    Chen, Yi-na; Zhao, Pu-sheng; He, Di; Dong, Fan; Zhao, Xiu-juan; Zhang, Xiao-ling

    2015-10-01

    In order to study the characteristics of atmospheric extinction coefficient in Beijing, systematic measurements had been carried out for atmospheric visibility, PM2.5 concentration, scattering coefficient, black carbon, reactive gases, and meteorological parameters from 2013 to 2014. Based on these data, we compared some published fitting schemes of aerosol light scattering enhancement factor [ f(RH)], and discussed the characteristics and the key influence factors for atmospheric extinction coefficient. Then a set of parameterization models of atmospheric extinction coefficient for different seasons and different polluted levels had been established. The results showed that aerosol scattering accounted for more than 94% of total light extinction. In the summer and autumn, the aerosol hygroscopic growth caused by high relative humidity had increased the aerosol scattering coefficient by 70 to 80 percent. The parameterization models could reflect the influencing mechanism of aerosol and relative humidity upon ambient light extinction, and describe the seasonal variations of aerosol light extinction ability.

  2. LIVAS: a 3-D multi-wavelength aerosol/cloud climatology based on CALIPSO and EARLINET

    NASA Astrophysics Data System (ADS)

    Amiridis, V.; Marinou, E.; Tsekeri, A.; Wandinger, U.; Schwarz, A.; Giannakaki, E.; Mamouri, R.; Kokkalis, P.; Binietoglou, I.; Solomos, S.; Herekakis, T.; Kazadzis, S.; Gerasopoulos, E.; Balis, D.; Papayannis, A.; Kontoes, C.; Kourtidis, K.; Papagiannopoulos, N.; Mona, L.; Pappalardo, G.; Le Rille, O.; Ansmann, A.

    2015-01-01

    We present LIVAS, a 3-dimentional multi-wavelength global aerosol and cloud optical climatology, optimized to be used for future space-based lidar end-to-end simulations of realistic atmospheric scenarios as well as retrieval algorithm testing activities. LIVAS database provides averaged profiles of aerosol optical properties for the potential space-borne laser operating wavelengths of 355, 532, 1064, 1570 and 2050 nm and of cloud optical properties at the wavelength of 532 nm. The global climatology is based on CALIPSO observations at 532 and 1064 nm and on aerosol-type-dependent spectral conversion factors for backscatter and extinction, derived from EARLINET ground-based measurements for the UV and scattering calculations for the IR wavelengths, using a combination of input data from AERONET, suitable aerosol models and recent literature. The required spectral conversion factors are calculated for each of the CALIPSO aerosol types and are applied to CALIPSO extinction and backscatter data correspondingly to the aerosol type retrieved by the CALIPSO aerosol classification scheme. A cloud climatology based on CALIPSO measurements at 532 nm is also provided, neglecting wavelength conversion due to approximately neutral scattering behavior of clouds along the spectral range of LIVAS. Averages of particle linear depolarization ratio profiles at 532 nm are provided as well. Finally, vertical distributions for a set of selected scenes of specific atmospheric phenomena (e.g., dust outbreaks, volcanic eruptions, wild fires, polar stratospheric clouds) are analyzed and spectrally converted so as to be used as case studies for space-borne lidar performance assessments. The final global climatology includes 4-year (1 January 2008-31 December 2011) time-averaged CALIPSO data on a uniform grid of 1×1 degree with the original high vertical resolution of CALIPSO in order to ensure realistic simulations of the atmospheric variability in lidar end-to-end simulations.

  3. Using Raman-lidar-based regularized microphysical retrievals and Aerosol Mass Spectrometer measurements for the characterization of biomass burning aerosols

    NASA Astrophysics Data System (ADS)

    Samaras, Stefanos; Nicolae, Doina; Böckmann, Christine; Vasilescu, Jeni; Binietoglou, Ioannis; Labzovskii, Lev; Toanca, Florica; Papayannis, Alexandros

    2015-10-01

    In this work we extract the microphysical properties of aerosols for a collection of measurement cases with low volume depolarization ratio originating from fire sources captured by the Raman lidar located at the National Institute of Optoelectronics (INOE) in Bucharest. Our algorithm was tested not only for pure smoke but also for mixed smoke and urban aerosols of variable age and growth. Applying a sensitivity analysis on initial parameter settings of our retrieval code was proved vital for producing semi-automatized retrievals with a hybrid regularization method developed at the Institute of Mathematics of Potsdam University. A direct quantitative comparison of the retrieved microphysical properties with measurements from a Compact Time of Flight Aerosol Mass Spectrometer (CToF-AMS) is used to validate our algorithm. Microphysical retrievals performed with sun photometer data are also used to explore our results. Focusing on the fine mode we observed remarkable similarities between the retrieved size distribution and the one measured by the AMS. More complicated atmospheric structures and the factor of absorption appear to depend more on particle radius being subject to variation. A good correlation was found between the aerosol effective radius and particle age, using the ratio of lidar ratios (LR: aerosol extinction to backscatter ratios) as an indicator for the latter. Finally, the dependence on relative humidity of aerosol effective radii measured on the ground and within the layers aloft show similar patterns.

  4. Spatial and temporal distribution of Arctic aerosols: new insights from the CALIPSO satellite

    NASA Astrophysics Data System (ADS)

    Di Pierro, Maurizio

    The Arctic is a receptor of pollution transported from distant regions. Pollution reaches the Arctic both in gaseous and aerosol form, both of which have important climatic and ecological implications. This dissertation focuses on aerosols in the Arctic, specifically their transport to and their distribution in space and time within the arctic troposphere. The cornerstone of this thesis is the analysis of the retrievals made by the satellite-borne Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP), a two-wavelength polarization-sensitive lidar that measures the atmospheric attenuated backscatter return and provides high-resolution vertical profiles of aerosols and clouds. Chapter 2 uses CALIOP observations to follow the evolution of pollution aerosols transported from East Asia to the Arctic. The transport pathway is elucidated with backtrajectories and aerosol simulations with the GEOS-Chem chemical transport model. The polluted air mass experiences strong ascent within a cyclonic circulation near the source region. Once in the free troposphere, a block in the upper-air flow forces the circulation to take on a strongly southerly route. Since the air mass reaches the Arctic very rapidly (3-5 days), the aerosol scavenging is incomplete. Transport is nearly-isentropic except in its initial phase. Once in the Arctic, the aerosol plume slowly subsides due to radiative cooling. Using six years of CALIOP observations, Chapter 3 focuses on the horizontal, vertical and temporal distribution of Arctic aerosols. At low altitudes in the High Arctic (poleward of 70°N), aerosol extinctions maximize in winter/early spring and reach their lowest values during summer. In the lower troposphere in the Low Arctic, in addition to the winter/early spring maximum, aerosol extinctions also display a secondary maximum in summer due to boreal forest fires. CALIOP measurements show that a major low-level Eurasian pollution transport pathway occurs on the western flank of the

  5. Comparison of the aerosol optical properties and size distribution retrieved by sun photometer with in situ measurements at midlatitude

    NASA Astrophysics Data System (ADS)

    Chauvigné, Aurélien; Sellegri, Karine; Hervo, Maxime; Montoux, Nadège; Freville, Patrick; Goloub, Philippe

    2016-09-01

    Aerosols influence the Earth radiative budget through scattering and absorption of solar radiation. Several methods are used to investigate aerosol properties and thus quantify their direct and indirect impacts on climate. At the Puy de Dôme station, continuous high-altitude near-surface in situ measurements and low-altitude ground-based remote sensing atmospheric column measurements give the opportunity to compare the aerosol extinction measured with both methods over a 1-year period. To our knowledge, it is the first time that such a comparison is realised with continuous measurements of a high-altitude site during a long-term period. This comparison addresses to which extent near-surface in situ measurements are representative of the whole atmospheric column, the aerosol mixing layer (ML) or the free troposphere (FT). In particular, the impact of multi-aerosol layers events detected using lidar backscatter profiles is analysed. A good correlation between in situ aerosol extinction coefficient and aerosol optical depth (AOD) measured by the Aerosol Robotic Network (AERONET) sun photometer is observed with a correlation coefficient around 0.80, indicating that the in situ measurements station is representative of the overall atmospheric column. After filtering for multilayer cases and correcting for each layer optical contribution (ML and FT), the atmospheric structure seems to be the main factor influencing the comparison between the two measurement techniques. When the site lies in the ML, the in situ extinction represents 45 % of the sun photometer ML extinction while when the site lies within the FT, the in situ extinction is more than 2 times higher than the FT sun photometer extinction. Moreover, the assumption of a decreasing linear vertical aerosol profile in the whole atmosphere has been tested, significantly improving the instrumental agreement. Remote sensing retrievals of the aerosol particle size distributions (PSDs) from the sun photometer

  6. 2014 iAREA campaign on aerosol in Spitsbergen - Part 2: Optical properties from Raman-lidar and in-situ observations at Ny-Ålesund

    NASA Astrophysics Data System (ADS)

    Ritter, C.; Neuber, R.; Schulz, Alexander; Markowicz, K. M.; Stachlewska, I. S.; Lisok, J.; Makuch, P.; Pakszys, P.; Markuszewski, P.; Rozwadowska, A.; Petelski, T.; Zielinski, T.; Becagli, S.; Traversi, R.; Udisti, R.; Gausa, M.

    2016-09-01

    In this work multi wavelength Raman lidar data from Ny-Ålesund, Spitsbergen have been analysed for the spring 2014 Arctic haze season, as part of the iAREA campaign. Typical values and probability distributions for aerosol backscatter, extinction and depolarisation, the lidar ratio and the color ratio for 4 different altitude intervals within the troposphere are given. These quantities and their dependencies are analysed and the frequency of altitude-dependent observed aerosol events are given. A comparison with ground-based size distribution and chemical composition is performed. Hence the aim of this paper is to provide typical and statistically meaningful properties of Arctic aerosol, which may be used in climate models or to constrain the radiative forcing. We have found that the 2014 season was only moderately polluted with Arctic haze and that sea salt and sulphate were the most dominant aerosol species. Moreover the drying of an aerosol layer after cloud disintegration has been observed. Hardly any clear temporal evolution over the 4 week data set on Arctic haze is obvious with the exception of the extinction coefficient and the lidar ratio, which significantly decreased below 2 km altitude by end April. In altitudes between 2 and 5 km the haze season lasted longer and the aerosol properties were generally more homogeneous than closer to the surface. Above 5 km only few particles were found. The variability of the lidar ratio is discussed. It was found that knowledge of the aerosol's size and shape does not determine the lidar ratio. Contrary to shape and lidar ratio, there is a clear correlation between size and backscatter: larger particles show a higher backscatter coefficient.

  7. Stratospheric aerosol acidity, density, and refractive index deduced from SAGE 2 and NMC temperature data

    NASA Technical Reports Server (NTRS)

    Yue, G. K.; Poole, L. R.; Wang, P.-H.; Chiou, E. W.

    1994-01-01

    Water vapor concentrations obtained by the Stratospheric Aerosol and Gas Experiment 2 (SAGE 2) and collocated temperatures provided by the National Meteorological Center (NMC) from 1986 to 1990 are used to deduce seasonally and zonally averaged acidity, density, and refractive index of stratospheric aerosols. It is found that the weight percentage of sulfuric acid in the aerosols increases from about 60 just above the tropopause to about 86 at 35 km. The density increases from about 1.55 to 1.85 g/cu cm between the same altitude limits. Some seasonal variations of composition and density are evident at high latitudes. The refractive indices at 1.02, 0.694, and 0.532 micrometers increase, respectively, from about 1.425, 1.430, and 1.435 just above the tropopause to about 1.445, 1.455, and 1.458 at altitudes above 27 km, depending on the season and latitude. The aerosol properties presented can be used in models to study the effectiveness of heterogeneous chemistry, the mass loading of stratospheric aerosols, and the extinction and backscatter of aerosols at different wavelengths. Computed aerosol surface areas, rate coefficients for the heterogeneous reaction ClONO2 + H2O yields HOCl + HNO3 and aerosol mass concentrations before and after the Pinatubo eruption in June 1991 are shown as sample applications.

  8. Lidar data assimilation for improved analyses of volcanic aerosol events

    NASA Astrophysics Data System (ADS)

    Lange, Anne Caroline; Elbern, Hendrik

    2014-05-01

    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

  9. Vertically-resolved profiles of mass concentrations and particle backscatter coefficients of Asian dust plumes derived from lidar observations of silicon dioxide.

    PubMed

    Noh, Youngmin; Müller, Detlef; Shin, Sung-Kyun; Shin, Dongho; Kim, Young J

    2016-01-01

    This study presents a method to retrieve vertically-resolved profiles of dust mass concentrations by analyzing Raman lidar signals of silicon dioxide (quartz) at 546nm. The observed particle plumes consisted of mixtures of East Asian dust with anthropogenic pollution. Our method for the first time allows for extracting the contribution of the aerosol component "pure dust" contained in the aerosol type "polluted dust". We also propose a method that uses OPAC (Optical Properties of Aerosols and Clouds) and the mass concentrations profiles of dust in order to derive profiles of backscatter coefficients of pure dust in mixed dust/pollution plumes. The mass concentration of silicon dioxide (quartz) in the atmosphere can be estimated from the backscatter coefficient of quartz. The mass concentration of dust is estimated by the weight percentage (38-77%) of mineral quartz in Asian dust. The retrieved dust mass concentrations are classified into water soluble, nucleation, accumulation, mineral-transported and coarse mode according to OPAC. The mass mixing ratio of 0.018, 0.033, 0.747, 0.130 and 0.072, respectively, is used. Dust extinction coefficients at 550nm were calculated by using OPAC and prescribed number concentrations for each of the 5 components. Dust backscatter coefficients were calculated from the dust extinction coefficients on the basis of a lidar ratio of 45±3sr at 532nm. We present results of quartz-Raman measurements carried out on the campus of the Gwangju Institute of Science and Technology (35.10°N, 126.53°E) on 15, 16, and 21 March 2010.

  10. Aerosol plume transport and transformation in high spectral resolution lidar measurements and WRF-Flexpart simulations during the MILAGRO Field Campaign

    NASA Astrophysics Data System (ADS)

    de Foy, B.; Burton, S. P.; Ferrare, R. A.; Hostetler, C. A.; Hair, J. W.; Wiedinmyer, C.; Molina, L. T.

    2011-04-01

    The Mexico City Metropolitan Area (MCMA) experiences high loadings of atmospheric aerosols from anthropogenic sources, biomass burning and wind-blown dust. This paper uses a combination of measurements and numerical simulations to identify different plumes affecting the basin and to characterize transformation inside the plumes. The High Spectral Resolution Lidar on board the NASA LaRC B-200 King Air aircraft measured extinction coefficients and extinction to backscatter ratio at 532 nm, and backscatter coefficients and depolarization ratios at 532 and 1064 nm. These can be used to identify aerosol types. The measurement curtains are compared with particle trajectory simulations using WRF-Flexpart for different source groups. The good correspondence between measurements and simulations suggests that the aerosol transport is sufficiently well characterized by the models to estimate aerosol types and ages. Plumes in the basin undergo complex transport, and are frequently mixed together. Urban aerosols are readily identifiable by their low depolarization ratios and high lidar ratios, and dust by the opposite properties. Fresh biomass burning plumes have very low depolarization ratios which increase rapidly with age. This rapid transformation is consistent with the presence of atmospheric tar balls in the fresh plumes.

  11. Aerosol plume transport and transformation in high spectral resolution lidar measurements and WRF-Flexpart simulations during the MILAGRO Field Campaign

    NASA Astrophysics Data System (ADS)

    de Foy, B.; Burton, S. P.; Ferrare, R. A.; Hostetler, C. A.; Hair, J. W.; Wiedinmyer, C.; Molina, L. T.

    2010-11-01

    The Mexico City Metropolitan Area (MCMA) experiences high loadings of atmospheric aerosols from anthropogenic sources, biomass burning and wind-blown dust. This paper uses a combination of measurements and numerical simulations to identify different plumes affecting the basin and to characterize transformation inside the plumes. The airborne High Spectral Resolution Lidar measures extinction coefficients and extinction to backscatter ratio at 532 nm, and backscatter coefficients and depolarization ratios at 532 and 1064 nm. These can be used to identify aerosol types. The measurement curtains are compared with particle trajectory simulations using WRF-Flexpart for different source groups. The good correspondence between measurements and simulations suggests that the aerosol transport is sufficiently well characterized by the models to estimate aerosol types and ages. Plumes in the basin undergo complex transport, and are frequently mixed together. Urban aerosols are readily identifiable by their low depolarization ratios and high lidar ratios, and dust by the opposite properties. Fresh biomass burning plumes have very low depolarization ratios which increase rapidly with age. This rapid transformation is consistent with the presence of atmospheric tar balls in the fresh plumes.

  12. Aerosol chemistry in GLOBE

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

    This task addresses the measurement and understanding of the physical and chemical properties of aerosol in remote regions that are responsible for aerosol backscatter at infrared wavelengths. Because it is representative of other clean areas, the remote Pacific is of extreme interest. Emphasis is on the determination size dependent aerosol properties that are required for modeling backscatter at various wavelengths and upon those features that may be used to help understand the nature, origin, cycling and climatology of these aerosols in the remote troposphere. Empirical relationships will be established between lidar measurements and backscatter derived from the aerosol microphysics as required by the NASA Doppler Lidar Program. This will include the analysis of results from the NASA GLOBE Survey Mission Flight Program. Additional instrument development and deployment will be carried out in order to extend and refine this data base. Identified activities include participation in groundbased and airborne experiments. Progress to date includes participation in, analysis of, and publication of results from Mauna Loa Backscatter Intercomparison Experiment (MABIE) and Global Backscatter Experiment (GLOBE).

  13. Measured Infrared Optical Cross Sections For a Variety Of Chemical and Biological Aerosol Simulants

    NASA Astrophysics Data System (ADS)

    Gurton, Kristan P.; Ligon, David; Dahmani, Rachid

    2004-08-01

    We conducted a series of spectral extinction measurements on a variety of aerosolized chemical and biological simulants over the spectral range 3-13 µm using conventional Fourier-transform IR (FTIR) aerosol spectroscopy. Samples consist of both aerosolized particulates and atomized liquids. Materials considered include Bacillus subtilis endospores, lyophilized ovalbumin, polyethylene glycol, dimethicone (SF-96), and three common background materials: kaolin clay (hydrated aluminum silicate), Arizona road dust (primarily SiO2), and diesel soot. Aerosol size distributions and mass density were measured simultaneously with the FTIR spectra. As a result, all optical parameters presented here are mass normalized, i.e., in square meters per gram. In an effort to establish the utility of using Mie theory to predict such parameters, we conducted a series of calculations. For materials in which the complex indices of refraction are known, e.g., silicone oil (SF-96) and kaolin, measured size distributions were convolved with Mie theory and the resultant spectral extinction calculated. Where there was good agreement between measured and calculated extinction spectra, absorption, total scattering, and backscatter were also calculated.

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

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

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

  15. Laboratory Experiments and Instrument Intercomparison Studies of Carbonaceous Aerosol Particles

    SciTech Connect

    Davidovits, Paul

    2015-10-20

    Aerosols containing black carbon (and some specific types of organic particulate matter) directly absorb incoming light, heating the atmosphere. In addition, all aerosol particles backscatter solar light, leading to a net-cooling effect. Indirect effects involve hydrophilic aerosols, which serve as cloud condensation nuclei (CCN) that affect cloud cover and cloud stability, impacting both atmospheric radiation balance and precipitation patterns. At night, all clouds produce local warming, but overall clouds exert a net-cooling effect on the Earth. The effect of aerosol radiative forcing on climate may be as large as that of the greenhouse gases, but predominantly opposite in sign and much more uncertain. The uncertainties in the representation of aerosol interactions in climate models makes it problematic to use model projections to guide energy policy. The objective of our program is to reduce the uncertainties in the aerosol radiative forcing in the two areas highlighted in the ASR Science and Program Plan. That is, (1) addressing the direct effect by correlating particle chemistry and morphology with particle optical properties (i.e. absorption, scattering, extinction), and (2) addressing the indirect effect by correlating particle hygroscopicity and CCN activity with particle size, chemistry, and morphology. In this connection we are systematically studying particle formation, oxidation, and the effects of particle coating. The work is specifically focused on carbonaceous particles where the uncertainties in the climate relevant properties are the highest. The ongoing work consists of laboratory experiments and related instrument inter-comparison studies both coordinated with field and modeling studies, with the aim of providing reliable data to represent aerosol processes in climate models. The work is performed in the aerosol laboratory at Boston College. At the center of our laboratory setup are two main sources for the production of aerosol particles: (a

  16. Development the EarthCARE aerosol classification scheme

    NASA Astrophysics Data System (ADS)

    Wandinger, Ulla; Baars, Holger; Hünerbein, Anja; Donovan, Dave; van Zadelhoff, Gerd-Jan; Fischer, Jürgen; von Bismarck, Jonas; Eisinger, Michael; Lajas, Dulce; Wehr, Tobias

    2015-04-01

    The Earth Clouds, Aerosols and Radiation Explorer (EarthCARE) mission is a joint ESA/JAXA mission planned to be launched in 2018. The multi-sensor platform carries a cloud-profiling radar (CPR), a high-spectral-resolution cloud/aerosol lidar (ATLID), a cloud/aerosol multi-spectral imager (MSI), and a three-view broad-band radiometer (BBR). Three out of the four instruments (ATLID, MSI, and BBR) will be able to sense the global aerosol distribution and contribute to the overarching EarthCARE goals of sensor synergy and radiation closure with respect to aerosols. The high-spectral-resolution lidar ATLID obtains profiles of particle extinction and backscatter coefficients, lidar ratio, and linear depolarization ratio as well as the aerosol optical thickness (AOT) at 355 nm. MSI provides AOT at 670 nm (over land and ocean) and 865 nm (over ocean). Next to these primary observables the aerosol type is one of the required products to be derived from both lidar stand-alone and ATLID-MSI synergistic retrievals. ATLID measurements of the aerosol intensive properties (lidar ratio, depolarization ratio) and ATLID-MSI observations of the spectral AOT will provide the basic input for aerosol-type determination. Aerosol typing is needed for the quantification of anthropogenic versus natural aerosol loadings of the atmosphere, the investigation of aerosol-cloud interaction, assimilation purposes, and the validation of atmospheric transport models which carry components like dust, sea salt, smoke and pollution. Furthermore, aerosol classification is a prerequisite for the estimation of direct aerosol radiative forcing and radiative closure studies. With an appropriate underlying microphysical particle description, the categorization of aerosol observations into predefined aerosol types allows us to infer information needed for the calculation of shortwave radiative effects, such as mean particle size, single-scattering albedo, and spectral conversion factors. In order to ensure

  17. Demonstration of Aerosol Property Profiling by Multi-wavelength Lidar Under Varying Relative Humidity Conditions

    NASA Technical Reports Server (NTRS)

    Whiteman, D.N.; Veselovskii, I.; Kolgotin, A.; Korenskii, M.; Andrews, E.

    2008-01-01

    The feasibility of using a multi-wavelength Mie-Raman lidar based on a tripled Nd:YAG laser for profiling aerosol physical parameters in the planetary boundary layer (PBL) under varying conditions of relative humidity (RH) is studied. The lidar quantifies three aerosol backscattering and two extinction coefficients and from these optical data the particle parameters such as concentration, size and complex refractive index are retrieved through inversion with regularization. The column-integrated, lidar-derived parameters are compared with results from the AERONET sun photometer. The lidar and sun photometer agree well in the characterization of the fine mode parameters, however the lidar shows less sensitivity to coarse mode. The lidar results reveal a strong dependence of particle properties on RH. The height regions with enhanced RH are characterized by an increase of backscattering and extinction coefficient and a decrease in the Angstrom exponent coinciding with an increase in the particle size. We present data selection techniques useful for selecting cases that can support the calculation of hygroscopic growth parameters using lidar. Hygroscopic growth factors calculated using these techniques agree with expectations despite the lack of co-located radiosonde data. Despite this limitation, the results demonstrate the potential of multi-wavelength Raman lidar technique for study of aerosol humidification process.

  18. High Spectral Resolution Lidar and MPLNET Micro Pulse Lidar Aerosol Optical Property Retrieval Intercomparison During the 2012 7-SEAS Field Campaign at Singapore

    NASA Technical Reports Server (NTRS)

    Lolli, Simone; Welton, Ellsworth J.; Campbell, James R.; Eloranta, Edwin; Holben, Brent N.; Chew, Boon Ning; Salinas, Santo V.

    2014-01-01

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

  19. High Spectral Resolution Lidar and MPLNET Micro Pulse Lidar aerosol optical property retrieval intercomparison during the 2012 7-SEAS field campaign at Singapore

    NASA Astrophysics Data System (ADS)

    Lolli, Simone; Welton, Ellsworth J.; Campbell, James R.; Eloranta, Edwin; Holben, Brent N.; Chew, Boom Ning; Salinas, Santo V.

    2014-10-01

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

  20. Series cell light extinction monitor

    DOEpatents

    Novick, Vincent J.

    1990-01-01

    A method and apparatus for using the light extinction measurements from two or more light cells positioned along a gasflow chamber in which the gas volumetric rate is known to determine particle number concentration and mass concentration of an aerosol independent of extinction coefficient and to determine estimates for particle size and mass concentrations. The invention is independent of particle size. This invention has application to measurements made during a severe nuclear reactor fuel damage test.

  1. LASE Measurements of Water Vapor, Aerosol, and Cloud Distributions in Saharan Air Layers and Tropical Disturbances

    NASA Technical Reports Server (NTRS)

    Ismail, Syed; Ferrare, Richard A.; Browell, Edward V.; Kooi, Susan A.; Dunion, Jason P.; Heymsfield, Gerry; Notari, Anthony; Butler, Carolyn F.; Burton, Sharon; Fenn, Marta; Krishnamurti, T. N.; Chen, Gao; Anderson, Bruce

    2010-01-01

    LASE (Lidar Atmospheric Sensing Experiment) on-board the NASA DC-8 measured high resolution profiles of water vapor and aerosols, and cloud distributions in 14 flights over the eastern North Atlantic during the NAMMA (NASA African Monsoon Multidisciplinary Analyses) field experiment. These measurements were used to study African easterly waves (AEWs), tropical cyclones (TCs), and the Saharan Air Layer(s) (SAL). Interactions between the SAL and tropical air were observed during the early stages of the TC development. These LASE measurements represent the first simultaneous water vapor and aerosol lidar measurements to study the SAL and its impact on AEWs and TCs. Examples of profile measurements of aerosol scattering ratios, aerosol extinction coefficients, aerosol optical thickness, water vapor mixing ratios, RH, and temperature are presented to illustrate their characteristics in SAL, convection, and clear air regions. LASE data suggest that the SAL suppresses low-altitude convection at the convection-SAL interface region. Mid-level convection associated with the AEW and transport are likely responsible for high water vapor content observed in the southern regions of the SAL on August 20, 2008. This interaction is responsible for the transfer of about 7 x 10(exp 15) J latent heat energy within a day to the SAL. Measurements of lidar extinction-to-backscatter ratios in the range 36+/-5 to 45+/-5 are within the range of measurements from other lidar measurements of dust. LASE aerosol extinction and water vapor profiles are validated by comparison with onboard in situ aerosol measurements and GPS dropsonde water vapor soundings, respectively.

  2. Plasmon-resonant gold nanorods as low backscattering albedo contrast agents for optical coherence tomography.

    PubMed

    Oldenburg, Amy L; Hansen, Matthew N; Zweifel, Daniel A; Wei, Alexander; Boppart, Stephen A

    2006-07-24

    Plasmon-resonant gold nanorods are demonstrated as low backscattering albedo contrast agents for optical coherence tomography (OCT). We define the backscattering albedo, a', as the ratio of the backscattering to extinction coefficient. Contrast agents which modify a' within the host tissue phantoms are detected with greater sensitivity by the differential OCT measurement of both a' and extinction. Optimum sensitivity is achieved by maximizing the difference between contrast agents and tissue, |a'(ca) - a'(tiss)|. Low backscattering albedo gold nanorods (14x 44 nm; lambda(max) = 780 nm) within a high backscattering albedo tissue phantom with an uncertainty in concentration of 20% (randomized 2+/-0.4% intralipid) were readily detected at 82 ppm (by weight) in a regime where extinction alone could not discriminate nanorods. The estimated threshold of detection was 30 ppm.

  3. Mie lidar observations of lower tropospheric aerosols and clouds.

    PubMed

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

    2011-12-15

    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.

  4. Dynamic coherent backscattering mirror

    PubMed Central

    Xu, M.

    2016-01-01

    The phase of multiply scattered light has recently attracted considerable interest. Coherent backscattering is a striking phenomenon of multiple scattered light in which the coherence of light survives multiple scattering in a random medium and is observable in the direction space as an enhancement of the intensity of backscattered light within a cone around the retroreflection direction. Reciprocity also leads to enhancement of backscattering light in the spatial space. The random medium behaves as a reciprocity mirror which robustly converts a diverging incident beam into a converging backscattering one focusing at a conjugate spot in space. Here we first analyze theoretically this coherent backscattering mirror (CBM) phenomenon and then demonstrate the capability of CBM compensating and correcting both static and dynamic phase distortions occurring along the optical path. CBM may offer novel approaches for high speed dynamic phase corrections in optical systems and find applications in sensing and navigation. PMID:26937296

  5. Dynamic coherent backscattering mirror

    SciTech Connect

    Zeylikovich, I.; Xu, M.

    2016-02-15

    The phase of multiply scattered light has recently attracted considerable interest. Coherent backscattering is a striking phenomenon of multiple scattered light in which the coherence of light survives multiple scattering in a random medium and is observable in the direction space as an enhancement of the intensity of backscattered light within a cone around the retroreflection direction. Reciprocity also leads to enhancement of backscattering light in the spatial space. The random medium behaves as a reciprocity mirror which robustly converts a diverging incident beam into a converging backscattering one focusing at a conjugate spot in space. Here we first analyze theoretically this coherent backscattering mirror (CBM) phenomenon and then demonstrate the capability of CBM compensating and correcting both static and dynamic phase distortions occurring along the optical path. CBM may offer novel approaches for high speed dynamic phase corrections in optical systems and find applications in sensing and navigation.

  6. Seasonally Averaged CALIPSO Lidar Extinction Profiles Provide Three-Dimensional Distribution of Saharan Dust Over Northern Continental Africa

    NASA Astrophysics Data System (ADS)

    Tackett, J. L.; Winker, D. M.; Trepte, C. R.

    2010-12-01

    During each summer in the northern hemisphere dust plumes originating from the Saharan desert are lofted above the continent and transported across the Atlantic Ocean, with both direct and indirect effects on radiative forcing. The magnitude of these effects is poorly quantified and depends on many factors - in particular, the vertical distribution. Since dust aerosols influence the radiative budget on large spatial scales, it is important to characterize their optical properties in all three dimensions to enable climate models to properly account for dust loading and the consequent effect on Earth’s radiation budget. A standard metric for aerosol loading in the entire atmospheric column is aerosol optical depth (AOD), while a metric for loading as a function of altitude is the extinction coefficient. However, it is difficult to characterize aerosol extinction since few data sets provide extinction profiles with ample spatial and temporal coverage. Fortunately, the satellite based lidar CALIPSO now provides this opportunity with the recent version 3 release of its profile products in May 2010, featuring derived extinction coefficients. After five years in orbit, CALIPSO yields a large data set which can be used to generate enlightening statistics. This work explores the three dimensional distribution of dust aerosol optical properties over the Saharan desert by examining average profiles of extinction coefficients for the five summers CALIPSO has been in operation (June-August, 2006-2010). Column AOD values based on these mean extinction profiles are also reported and compared to collocated MODIS “deep blue AOD” values (new in collection 5). This comparison is interesting since MODIS was previously unable to derive AOD over bright surfaces such as the Saharan Desert. Examination of CALIPSO extinction in the vertical and MODIS AOD in the column over a seasonal average provides a three dimensional picture of dust loading in this region and highlights the

  7. Aerosol content survey by mini N 2 -Raman lidar: Application to local and long-range transport aerosols

    NASA Astrophysics Data System (ADS)

    Royer, Philippe; Chazette, Patrick; Lardier, Melody; Sauvage, Laurent

    2011-12-01

    This study shows an aerosol content survey in the low and middle troposphere over Paris with a compact and light Nitrogen-Raman lidar which has been recently developed by the Commissariat à l'Energie Atomique (CEA) and LEOSPHERE company. This eye-safe and wide field-of-view system (full overlap between 150 and 200 m) is particularly well-adapted to air pollution survey in the vicinity of Megalopolis. Extinction-to-backscatter coefficient (so-called Lidar Ratio LR) profiles obtained with a Tikhonov regularization scheme are presented for long-range transport events of aerosols (volcanic ash plume LR = 48 ± 10 sr, and desert dust, LR = 45 ± 8 sr) which may contribute to the local load of aerosols emitted by traffic and industries in Megalopolis. Due to an insufficient signal to noise ratio (SNR < 30), a new dichotomous algorithm has been developed to perform daytime inversions every hour which is in accordance with the typical time evolution of aerosols within the planetary boundary layer. This inversion scheme is based on the constraint of the elastic channel with the aerosol optical depth (between typically 0.2 and 0.7 km) determined with the N 2-Raman channel and thus only gives access to an equivalent LR between 0.2 and 0.7 km with a relative uncertainty lower than 15%. This approach has been applied to retrieve diurnal cycle of LR for polluted continental aerosols over Paris and is compared with Tikhonov regularization applied during the night. We found a mean value of 85 ± 18 sr for polluted continental aerosols which is in agreement with other studies performed around the Paris urban area. Results for aerosol optical properties are presented and the error sources are discussed for each approach.

  8. Measuring Extinction with ALE

    NASA Astrophysics Data System (ADS)

    Zimmer, Peter C.; McGraw, J. T.; Gimmestad, G. G.; Roberts, D.; Stewart, J.; Smith, J.; Fitch, J.

    2007-12-01

    ALE (Astronomical LIDAR for Extinction) is deployed at the University of New Mexico's (UNM) Campus Observatory in Albuquerque, NM. It has begun a year-long testing phase prior deployment at McDonald Observatory in support of the CCD/Transit Instrument II (CTI-II). ALE is designed to produce a high-precision measurement of atmospheric absorption and scattering above the observatory site every ten minutes of every moderately clear night. LIDAR (LIght Detection And Ranging) is the VIS/UV/IR analog of radar, using a laser, telescope and time-gated photodetector instead of a radio transmitter, dish and receiver. In the case of ALE -- an elastic backscatter LIDAR -- 20ns-long, eye-safe laser pulses are launched 2500 times per second from a 0.32m transmitting telescope co-mounted with a 50mm short-range receiver on an alt-az mounted 0.67m long-range receiver. Photons from the laser pulse are scattered and absorbed as the pulse propagates through the atmosphere, a portion of which are scattered into the field of view of the short- and long-range receiver telescopes and detected by a photomultiplier. The properties of a given volume of atmosphere along the LIDAR path are inferred from both the altitude-resolved backscatter signal as well as the attenuation of backscatter signal from altitudes above it. We present ALE profiles from the commissioning phase and demonstrate some of the astronomically interesting atmospheric information that can be gleaned from these data, including, but not limited to, total line-of-sight extinction. This project is funded by NSF Grant 0421087.

  9. Rethinking Extinction

    PubMed Central

    Dunsmoor, Joseph E.; Niv, Yael; Daw, Nathaniel; Phelps, Elizabeth A.

    2015-01-01

    Extinction serves as the leading theoretical framework and experimental model to describe how learned behaviors diminish through absence of anticipated reinforcement. In the past decade, extinction has moved beyond the realm of associative learning theory and behavioral experimentation in animals and has become a topic of considerable interest in the neuroscience of learning, memory, and emotion. Here, we review research and theories of extinction, both as a learning process and as a behavioral technique, and consider whether traditional understandings warrant a re-examination. We discuss the neurobiology, cognitive factors, and major computational theories, and revisit the predominant view that extinction results in new learning that interferes with expression of the original memory. Additionally, we reconsider the limitations of extinction as a technique to prevent the relapse of maladaptive behavior, and discuss novel approaches, informed by contemporary theoretical advances, that augment traditional extinction methods to target and potentially alter maladaptive memories. PMID:26447572

  10. Rethinking Extinction.

    PubMed

    Dunsmoor, Joseph E; Niv, Yael; Daw, Nathaniel; Phelps, Elizabeth A

    2015-10-07

    Extinction serves as the leading theoretical framework and experimental model to describe how learned behaviors diminish through absence of anticipated reinforcement. In the past decade, extinction has moved beyond the realm of associative learning theory and behavioral experimentation in animals and has become a topic of considerable interest in the neuroscience of learning, memory, and emotion. Here, we review research and theories of extinction, both as a learning process and as a behavioral technique, and consider whether traditional understandings warrant a re-examination. We discuss the neurobiology, cognitive factors, and major computational theories, and revisit the predominant view that extinction results in new learning that interferes with expression of the original memory. Additionally, we reconsider the limitations of extinction as a technique to prevent the relapse of maladaptive behavior and discuss novel approaches, informed by contemporary theoretical advances, that augment traditional extinction methods to target and potentially alter maladaptive memories.

  11. LIVAS: a 3-D multi-wavelength aerosol/cloud database based on CALIPSO and EARLINET

    NASA Astrophysics Data System (ADS)

    Amiridis, V.; Marinou, E.; Tsekeri, A.; Wandinger, U.; Schwarz, A.; Giannakaki, E.; Mamouri, R.; Kokkalis, P.; Binietoglou, I.; Solomos, S.; Herekakis, T.; Kazadzis, S.; Gerasopoulos, E.; Proestakis, E.; Kottas, M.; Balis, D.; Papayannis, A.; Kontoes, C.; Kourtidis, K.; Papagiannopoulos, N.; Mona, L.; Pappalardo, G.; Le Rille, O.; Ansmann, A.

    2015-07-01

    We present LIVAS (LIdar climatology of Vertical Aerosol Structure for space-based lidar simulation studies), a 3-D multi-wavelength global aerosol and cloud optical database, optimized to be used for future space-based lidar end-to-end simulations of realistic atmospheric scenarios as well as retrieval algorithm testing activities. The LIVAS database provides averaged profiles of aerosol optical properties for the potential spaceborne laser operating wavelengths of 355, 532, 1064, 1570 and 2050 nm and of cloud optical properties at the wavelength of 532 nm. The global database is based on CALIPSO observations at 532 and 1064 nm and on aerosol-type-dependent backscatter- and extinction-related Ångström exponents, derived from EARLINET (European Aerosol Research Lidar Network) ground-based measurements for the UV and scattering calculations for the IR wavelengths, using a combination of input data from AERONET, suitable aerosol models and recent literature. The required spectral conversions are calculated for each of the CALIPSO aerosol types and are applied to CALIPSO backscatter and extinction data corresponding to the aerosol type retrieved by the CALIPSO aerosol classification scheme. A cloud optical database based on CALIPSO measurements at 532 nm is also provided, neglecting wavelength conversion due to approximately neutral scattering behavior of clouds along the spectral range of LIVAS. Averages of particle linear depolarization ratio profiles at 532 nm are provided as well. Finally, vertical distributions for a set of selected scenes of specific atmospheric phenomena (e.g., dust outbreaks, volcanic eruptions, wild fires, polar stratospheric clouds) are analyzed and spectrally converted so as to be used as case studies for spaceborne lidar performance assessments. The final global data set includes 4-year (1 January 2008-31 December 2011) time-averaged CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) data on a uniform grid of 1

  12. Systematic Relationships Between Lidar Observables and Sizes And Mineral Composition Of Dust Aerosols

    NASA Technical Reports Server (NTRS)

    Van Diedenhoven, Bastiaan; Stangl, Alexander; Perlwitz, Jan; Fridlind, Ann M.; Chowdhary, Jacek; Cairns, Brian

    2015-01-01

    The physical and chemical properties of soil dust aerosol particles fundamentally affect their interaction with climate, including shortwave absorption and radiative forcing, nucleation of cloud droplets and ice crystals, heterogeneous formation of sulfates and nitrates on the surface of dust particles, and atmospheric processing of iron into bioavailable forms that increase the productivity of marine phytoplankton. Lidar measurements, such as extinction-to-backscatter, color and depolarization ratios, are frequently used to distinguish between aerosol types with different physical and chemical properties. The chemical composition of aerosol particles determines their complex refractive index, hence affecting their backscattering properties. Here we present a study on how dust aerosol backscattering and depolarization properties at wavelengths of 355, 532 and 1064 nm are related to size and complex refractive index, which varies with the mineral composition of the dust. Dust aerosols are represented by collections of spheroids with a range of prolate and oblate aspect ratios and their optical properties are obtained using T-matrix calculations. We find simple, systematic relationships between lidar observables and the dust size and complex refractive index that may aid the use of space-based or airborne lidars for direct retrieval of dust properties or for the evaluation of chemical transport models using forward simulated lidar variables. In addition, we present first results on the spatial variation of forward-simulated lidar variables based on a dust model that accounts for the atmospheric cycle of eight different mineral types plus internal mixtures of seven mineral types with iron oxides, which was recently implemented in the NASA GISS Earth System ModelE2.

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

    NASA Astrophysics Data System (ADS)

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

    2010-05-01

    Meteorological services rely, in part, on numerical weather prediction (NWP). Twice a day radiosonde observations of water vapor provide the required data for assimilation but this time resolution is insufficient to resolve certain meteorological phenomena. High time resolution temperature profiles from microwave radiometers are available as well but have rather low vertical resolution. The Raman LIDARs are able to provide temperature and humidity profiles with high time and range resolution, suitable for NWP model assimilation and validation. They are as well indispensible tools for continuous aerosol profiling for high resolution atmospheric boundary layer studies. To improve the database available for direct meteorological applications the Swiss meteo-service (MeteoSwiss), the Swiss Federal Institute of Technology in Lausanne (EPFL) and the Swiss National Science Foundation (SNSF) initiated a project to design and build an automated Raman lidar for day and night vertical profiling of tropospheric water vapor with the possibility to further upgrade it with an aerosol and temperature channels. The project was initiated in 2004 and RALMO (Raman Lidar for meteorological observations) was inaugurated in August 2008 at MeteoSwiss aerological station at Payerne. RALMO is currently operational and continuously profiles water vapor mixing ratio, aerosol backscatter ratio and aerosol extinction. The instrument is a fully automated, self-contained, eye-safe Raman lidar operated at 355 nm. Narrow field-of-view multi-telescope receiver and narrow band detection allow day and night-time vertical profiling of the atmospheric humidity. The rotational-vibrational Raman lidar responses from water vapor and nitrogen are spectrally separated by a high-throughput fiber coupled diffraction grating polychromator. The elastic backscatter and pure-rotational Raman lidar responses (PRR) from oxygen and nitrogen are spectrally isolated by a double grating polychromator and are used to

  14. Multi-year Cluster Analyses of CALIPSO Aerosol Layer Data

    NASA Astrophysics Data System (ADS)

    Omar, A. H.; Sumner, A. J.; Vaughan, M.

    2013-12-01

    The Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) mission, a collaboration between NASA and Centre National d'Études Spatiales (CNES), was launched in April 2006 to provide vertically resolved measurements of cloud and aerosol distributions. The primary instrument on the CALIPSO satellite is the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP), a near-nadir viewing two-wavelength polarization-sensitive instrument. The unique nature of CALIOP measurements make it quite challenging to validate backscatter profiles, aerosol type, and cloud phase, all of which are used to retrieve extinction and optical depth. We exploit the large data set generated by CALIPSO between 2006 - 2013 to find groups in the data from which we can infer aerosol type. We use classical clustering analyses (k-means) to group the data based on five Level 2 data parameters: integrated attenuated backscatter (532 nm), volume depolarization ratio, integrated attenuated color ratio, layer base altitude, and layer top altitude. The data are screened using standard CALIPSO quality assurance flags, cloud aerosol discrimination (CAD) scores, overlying features and layer properties. Furthermore, the data were standardized to a 'z score' in order to remove weighting bias due to arbitrary units. The k-means algorithm forms clusters by minimizing the Euclidian distance between each data point and its respective cluster centroid independently for each parameter. Silhouette coefficients, a dimensionless measure of internal cluster interrelation or consistency and external cluster separation or uniqueness were used to determine the validity of clusters. These investigations yielded optimally distinct clusters when six groups were formed similar to the result in Omar et al, 2005 which form the basis for the current CALIPSO aerosol subtypes. While the number of clusters in both studies coincide, the clusters do not match with all aerosol subtypes. Analysis of the data

  15. Atmospheric aerosol and Doppler lidar studies

    NASA Technical Reports Server (NTRS)

    Rothermel, Jeff; Bowdle, D. A.; Srivastava, V.; Jarzembski, M.; Cutten, D.; Mccaul, E. W., Jr.

    1991-01-01

    Experimental and theoretical studies were performed of atmospheric aerosol backscatter and atmospheric dynamics with Doppler lidar as a primary tool. Activities include field and laboratory measurement and analysis efforts. The primary focus of activities related to understanding aerosol backscatter is the GLObal Backscatter Experiment (GLOBE) program. GLOBE is a multi-element effort designed toward developing a global aerosol model to describe tropospheric clean background backscatter conditions that Laser Atmospheric Wind Sounder (LAWS) is likely to encounter. Two survey missions were designed and flown in the NASA DC-8 in November 1989 and May to June 1990 over the remote Pacific Ocean, a region where backscatter values are low and where LAWS wind measurements could make a major contribution. The instrument complement consisted of pulsed and continuous-wave (CW) CO2 gas and solid state lidars measuring aerosol backscatter, optical particle counters measuring aerosol concentration, size distribution, and chemical composition, a filter/impactor system collecting aerosol samples for subsequent analysis, and integrating nephelometers measuring visible scattering coefficients. The GLOBE instrument package and survey missions were carefully planned to achieve complementary measurements under clean background backscatter conditions.

  16. Seasonal variation of surface and vertical profile of aerosol properties over a tropical urban station Hyderabad, India

    NASA Astrophysics Data System (ADS)

    Sinha, P. R.; Manchanda, R. K.; Kaskaoutis, D. G.; Kumar, Y. B.; Sreenivasan, S.

    2013-01-01

    One year measurement of vertical profiles of volume backscatter and extinction coefficient, aerosol optical depth (AOD), mass concentration of black carbon (BC) and composite aerosol along with thermodynamic structure of the atmosphere has been carried out over an urban tropical location of Hyderabad(17.47°N, 78.58°E), India, during April 2009 to March 2010. The mean mixing layer height (MLH) exhibits large seasonality exceeding 4 km in pre-monsoon period whereas in winter it comes down to ~1.5 km with an annual mean value of 2.35 ± 1.02 km. Surface BC mass fraction (FBC) shows marked seasonal variation from winter (13 ± 1.9%), pre-monsoon (8.19 ± 2.16%), monsoon (7.3 ± 1.8%) to post-monsoon (11.8 ± 0.18%). The profiles of volume backscatter and extinction coefficients reveal presence of elevated aerosol layers from 2 to 4 km and strong oscillations during pre-monsoon (March-May) and monsoon (June-September) seasons, respectively, while in post-monsoon (October-November) and winter (December-February), the aerosols are well within the lower boundary layer and also exhibit a drastic decrease with increasing altitude. These elevated aerosol layers and vertical distribution appear to be closely linked to the thermodynamic structure of the atmosphere. The aerosol optical properties in conjunction with air mass back trajectory analysis indicate that the observed elevated aerosol layers during pre-monsoon and monsoon could contain significant fraction of coarse mode particles with a mix of dust and marine aerosols. Further analysis reveals that the aerosols within atmospheric boundary layer (ABL) dominate the column aerosol loading with ABL-AOD contributing to ~77.7 ± 17.0%, with significant seasonal variation from winter (86.2 ± 13.1%), pre-monsoon (76.6 ± 12.8%), monsoon (54.2 ± 15.6%) to post monsoon (80.8 ± 14.8%). Seasonal variation of ABL-AOD and BC mass fraction follows similar pattern in the ABL indicating that BC may be an important contributor to

  17. Light extinction in the atmosphere

    SciTech Connect

    Laulainen, N.

    1992-06-01

    Atmospheric aerosol particles originating from natural sources, such as volcanos and sulfur-bearing gas emissions from the oceans, and from human sources, such as sulfur emissions from fossil fuel combustion and biomass burning, strongly affect visual air quality and are suspected to significantly affect radiative climate forcing of the planet. During the daytime, aerosols obscure scenic vistas, while at night they diminish our ability to observe stellar objects. Scattering of light is the main means by which aerosols attenuate and redistribute light in the atmosphere and by which aerosols can alter and reduce visibility and potentially modify the energy balance of the planet. Trends and seasonal variability of atmospheric aerosol loading, such as column-integrated light extinction or optical depth, and how they may affect potential climate change have been difficult to quantify because there have been few observations made of important aerosol optical parameters, such as optical depth, over the globe and over time and often these are of uneven quality. To address questions related to possible climate change, there is a pressing need to acquire more high-quality aerosol optical depth data. Extensive deployment of improved solar radiometers over the next few years will provide higher-quality extinction data over a wider variety of locations worldwide. An often overlooked source of turbidity data, however, is available from astronomical observations, particularly stellar photoelectric photometry observations. With the exception of the Project ASTRA articles published almost 20 years ago, few of these data ever appear in the published literature. This paper will review the current status of atmospheric extinction observations, as highlighted by the ASTRA work and augmented by more recent solar radiometry measurements.

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

    SciTech Connect

    Hostetler, Chris; Ferrare, Richard

    2013-02-14

    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

  19. Airborne Sunphotometry of African Dust and Marine Boundary Layer Aerosols in PRIDE

    NASA Technical Reports Server (NTRS)

    Livingston, John M.; Redemann, Jens; Russell, Philip; Schmid, Beat; Reid, Jeff; Pilewskie, Peter; Hipskind, R. Stephen (Technical Monitor)

    2000-01-01

    The Puerto Rico Dust Experiment (PRIDE) was conducted during summer 2000 to study the radiative, microphysical and transport properties of Saharan dust in the Caribbean region. During PRIDE, NASA Ames Research Center's six-channel airborne autotracking sunphotometer (AATS-6) was operated aboard a Piper Navajo airplane based at Roosevelt Roads Naval Station on the northeast coast of Puerto Rico. AATS-6 measurements were taken during 21 science flights off the coast of Puerto Rico in the western Caribbean. Data were acquired within and above the Marine Boundary Layer (MBL) and the Saharan Aerosol Layer (SAL) up to 5.5 km altitude tinder a wide range of dust loadings. Aerosol optical depth (AOD) spectra and columnar water vapor (CWV) values have been calculated from the AATS-6 measurements by using sunphotometer calibration data obtained at Mauna Loa Observatory (3A kin ASL) before (May) and after (October) PRIDE. Mid-visible AOD values measured near the surface during PRIDE ranged from 0.07 on the cleanest day to 0.55 on the most turbid day. Values measured above the MBL were as high as 0.35; values above the SAL were as low as 0.01. The fraction of total column AOD due to Saharan dust cannot be determined precisely from AATS-6 AOD data alone due to the uncertainty in the extent of vertical mixing of the dust down through the MBL. However, analyses of ground-based and airborne in-situ aerosol sampling measurements and ground-based aerosol lidar backscatter data should yield accurate characterization of the vertical mixing that will enable calculation of the Saharan dust AOD component from the sunphotometer data. Examples will be presented showing measured AATS-6 AOD spectra, calculated aerosol extinction and water vapor density vertical profiles, and aerosol size distributions retrieved by inversion of the AOD spectra. Near sea-surface AOD spectra acquired by AATS-6 during horizontal flight legs at 30 m ASL are available for validation of AOD derived from coincident

  20. Global aerosol typing from a combination of A-Train satellite observations in clear-sky and above clouds

    NASA Astrophysics Data System (ADS)

    Kacenelenbogen, M. S.; Russell, P. B.; Vaughan, M.; Redemann, J.; Shinozuka, Y.; Livingston, J. M.; Zhang, Q.

    2014-12-01

    According to the 5th Assessment Report of the Intergovernmental Panel on Climate Change (IPCC), the model estimates of Radiative Forcing due to aerosol-radiation interactions (RFari) for individual aerosol types are less certain than the total RFari [Boucher et al., 2013]. For example, the RFari specific to Black Carbon (BC) is uncertain due to an underestimation of its mass concentration near source regions [Koch et al., 2009]. Several recent studies have evaluated chemical transport model (CTM) predictions using observations of aerosol optical properties such as Aerosol Optical Depth (AOD) or Single Scattering Albedo (SSA) from satellite or ground-based instruments (e.g., Huneeus et al., [2010]). However, most passive remote sensing instruments fail to provide a comprehensive assessment of the particle type without further analysis and combination of measurements. To improve the predictions of aerosol composition in CTMs, we have developed an aerosol classification algorithm (called Specified Clustering and Mahalanobis Classification, SCMC) that assigns an aerosol type to multi-parameter retrievals by spaceborne, airborne or ground based passive remote sensing instruments [Russell et al., 2014]. The aerosol types identified by our scheme are pure dust, polluted dust, urban-industrial/developed economy, urban-industrial/developing economy, dark biomass smoke, light biomass smoke and pure marine. First, we apply the SCMC method to five years of clear-sky space-borne POLDER observations over Greece. We then use the aerosol extinction and SSA spectra retrieved from a combination of MODIS, OMI and CALIOP clear-sky observations to infer the aerosol type over the globe in 2007. Finally, we will extend the spaceborne aerosol classification from clear-sky to above low opaque water clouds using a combination of CALIOP AOD and backscatter observations and OMI absorption AOD values from near-by clear-sky pixels.

  1. Aircraft Measurements of BrO, IO, Glyoxal, NO2, H2O, O2-O2 and Aerosol Extinction Profiles in the Tropics: Comparison with Aircraft-/Ship-Based in Situ and Lidar Measurements

    NASA Technical Reports Server (NTRS)

    Volkamer, R.; Baidar, S.; Campos, T. L.; Coburn, S.; DiGangi, J. P.; Dix, B.; Eloranta, E. W.; Koenig, T. K.; Morley, B.; Ortega, I.; Pierce, B. R.; Reeves, M.; Sinreich, R.; Wang, S.; Zondlo, M. A.; Romashkin, P. A.

    2015-01-01

    Tropospheric chemistry of halogens and organic carbon over tropical oceans modifies ozone and atmospheric aerosols, yet atmospheric models remain largely untested for lack of vertically resolved measurements of bromine monoxide (BrO), iodine monoxide (IO) and small oxygenated hydrocarbons like glyoxal (CHOCHO) in the tropical troposphere. BrO, IO, glyoxal, nitrogen dioxide (NO2), water vapor (H2O) and O2-O2 collision complexes (O4/ were measured by the University of Colorado Airborne Multi-AXis Differential Optical Absorption Spectroscopy (CU AMAXDOAS) instrument, aerosol extinction by high spectral resolution lidar (HSRL), in situ aerosol size distributions by an ultra high sensitivity aerosol spectrometer (UHSAS) and in situ H2O by vertical-cavity surface-emitting laser (VCSEL) hygrometer. Data are presented from two research flights (RF12, RF17) aboard the National Science Foundation/ National Center for Atmospheric Research Gulfstream V aircraft over the tropical Eastern Pacific Ocean (tEPO) as part of the "Tropical Ocean tRoposphere Exchange of Reactive halogens and Oxygenated hydrocarbons" (TORERO) project (January/February 2012). We assess the accuracy of O4 slant column density (SCD) measurements in the presence and absence of aerosols. Our O4-inferred aerosol extinction profiles at 477 nm agree within 6% with HSRL in the boundary layer and closely resemble the renormalized profile shape of Mie calculations constrained by UHSAS at low (sub-Rayleigh) aerosol extinction in the free troposphere. CU AMAX-DOAS provides a flexible choice of geometry, which we exploit to minimize the SCD in the reference spectrum (SCDREF, maximize signal-to-noise ratio) and to test the robustness of BrO, IO and glyoxal differential SCDs. The RF12 case study was conducted in pristine marine and free tropospheric air. The RF17 case study was conducted above the NOAA RV Ka'imimoana (TORERO cruise, KA-12-01) and provides independent validation data from ship-based in situ cavity

  2. Aircraft measurements of BrO, IO, glyoxal, NO2, H2O, O2-O2 and aerosol extinction profiles in the tropics: comparison with aircraft-/ship-based in situ and lidar measurements

    NASA Astrophysics Data System (ADS)

    Volkamer, R.; Baidar, S.; Campos, T. L.; Coburn, S.; DiGangi, J. P.; Dix, B.; Eloranta, E. W.; Koenig, T. K.; Morley, B.; Ortega, I.; Pierce, B. R.; Reeves, M.; Sinreich, R.; Wang, S.; Zondlo, M. A.; Romashkin, P. A.

    2015-05-01

    Tropospheric chemistry of halogens and organic carbon over tropical oceans modifies ozone and atmospheric aerosols, yet atmospheric models remain largely untested for lack of vertically resolved measurements of bromine monoxide (BrO), iodine monoxide (IO) and small oxygenated hydrocarbons like glyoxal (CHOCHO) in the tropical troposphere. BrO, IO, glyoxal, nitrogen dioxide (NO2), water vapor (H2O) and O2-O2 collision complexes (O4) were measured by the University of Colorado Airborne Multi-AXis Differential Optical Absorption Spectroscopy (CU AMAX-DOAS) instrument, aerosol extinction by high spectral resolution lidar (HSRL), in situ aerosol size distributions by an ultra high sensitivity aerosol spectrometer (UHSAS) and in situ H2O by vertical-cavity surface-emitting laser (VCSEL) hygrometer. Data are presented from two research flights (RF12, RF17) aboard the National Science Foundation/National Center for Atmospheric Research Gulfstream V aircraft over the tropical Eastern Pacific Ocean (tEPO) as part of the "Tropical Ocean tRoposphere Exchange of Reactive halogens and Oxygenated hydrocarbons" (TORERO) project (January/February 2012). We assess the accuracy of O4 slant column density (SCD) measurements in the presence and absence of aerosols. Our O4-inferred aerosol extinction profiles at 477 nm agree within 6% with HSRL in the boundary layer and closely resemble the renormalized profile shape of Mie calculations constrained by UHSAS at low (sub-Rayleigh) aerosol extinction in the free troposphere. CU AMAX-DOAS provides a flexible choice of geometry, which we exploit to minimize the SCD in the reference spectrum (SCDREF, maximize signal-to-noise ratio) and to test the robustness of BrO, IO and glyoxal differential SCDs. The RF12 case study was conducted in pristine marine and free tropospheric air. The RF17 case study was conducted above the NOAA RV Ka'imimoana (TORERO cruise, KA-12-01) and provides independent validation data from ship-based in situ cavity

  3. SAGE II aerosol data validation based on retrieved aerosol model size distribution from SAGE II aerosol measurements

    NASA Technical Reports Server (NTRS)

    Wang, Pi-Huan; Mccormick, M. P.; Mcmaster, L. R.; Chu, W. P.; Swissler, T. J.; Osborn, M. T.; Russell, P. B.; Oberbeck, V. R.; Livingston, J.; Rosen, J. M.

    1989-01-01

    Consideration is given to aerosol correlative measurements experiments for the Stratospheric Aerosol and Gas Experiment (SAGE) II, conducted between November 1984 and July 1986. The correlative measurements were taken with an impactor/laser probe, a dustsonde, and an airborne 36-cm lidar system. The primary aerosol quantities measured by the ground-based instruments are compared with those calculated from the aerosol size distributions from SAGE II aerosol extinction measurements. Good agreement is found between the two sets of measurements.

  4. Observations of rapid aerosol optical depth enhancements in the vicinity of polluted cumulus clouds

    NASA Astrophysics Data System (ADS)

    Eck, T. F.; Holben, B. N.; Reid, J. S.; Arola, A.; Ferrare, R. A.; Hostetler, C. A.; Crumeyrolle, S. N.; Berkoff, T. A.; Welton, E. J.; Lolli, S.; Lyapustin, A.; Wang, Y.; Schafer, J. S.; Giles, D. M.; Anderson, B. E.; Thornhill, K. L.; Minnis, P.; Pickering, K. E.; Loughner, C. P.; Smirnov, A.; Sinyuk, A.

    2014-11-01

    During the July 2011 Deriving Information on Surface conditions from Column and Vertically Resolved Observations Relevant to Air Quality (DISCOVER-AQ) field experiment in Maryland, significant enhancements in Aerosol Robotic Network (AERONET) sun-sky radiometer measured aerosol optical depth (AOD) were observed in the immediate vicinity of non-precipitating cumulus clouds on some days. Both measured Ångström exponents and aerosol size distribution retrievals made before, during and after cumulus development often suggest little change in fine mode particle size; therefore, implying possible new particle formation in addition to cloud processing and humidification of existing particles. In addition to sun-sky radiometer measurements of large enhancements of fine mode AOD, lidar measurements made from both ground-based and aircraft-based instruments during the experiment also measured large increases in aerosol signal at altitudes associated with the presence of fair weather cumulus clouds. These data show modifications of the aerosol vertical profile as a result of the aerosol enhancements at and below cloud altitudes. The airborne lidar data were utilized to estimate the spatial extent of these aerosol enhancements, finding increased AOD, backscatter and extinction out to 2.5 km distance from the cloud edge. Furthermore, in situ measurements made from aircraft vertical profiles over an AERONET site during the experiment also showed large increases in aerosol scattering and aerosol volume after cloud formation as compared to before. The 15-year AERONET database of AOD measurements at the Goddard Space Flight Center (GSFC), Maryland site, was investigated in order to obtain a climatological perspective of this phenomenon of AOD enhancement. Analysis of the diurnal cycle of AOD in summer showed significant increases in AOD from morning to late afternoon, corresponding to the diurnal cycle of cumulus development.

  5. Final Technical Report for Interagency Agreement No. DE-SC0005453 “Characterizing Aerosol Distributions, Types, and Optical and Microphysical Properties using the NASA Airborne High Spectral Resolution Lidar (HSRL) and the Research Scanning Polarimeter (RSP)”

    SciTech Connect

    Hostetler, Chris; Ferrare, Richard

    2015-01-13

    Measurements of the vertical profile of atmospheric aerosols and aerosol optical and microphysical characteristics are required to: 1) determine aerosol direct and indirect radiative forcing, 2) compute radiative flux and heating rate profiles, 3) assess model simulations of aerosol distributions and types, and 4) establish the ability of surface and space-based remote sensors to measure the indirect effect. Consequently the ASR program calls for a combination of remote sensing and in situ measurements to determine aerosol properties and aerosol influences on clouds and radiation. As part of our previous DOE ASP project, we deployed the NASA Langley airborne High Spectral Resolution Lidar (HSRL) on the NASA B200 King Air aircraft during major field experiments in 2006 (MILAGRO and MaxTEX), 2007 (CHAPS), 2009 (RACORO), and 2010 (CalNex and CARES). The HSRL provided measurements of aerosol extinction (532 nm), backscatter (532 and 1064 nm), and depolarization (532 and 1064 nm). These measurements were typically made in close temporal and spatial coincidence with measurements made from DOE-funded and other participating aircraft and ground sites. On the RACORO, CARES, and CalNEX missions, we also deployed the NASA Goddard Institute for Space Studies (GISS) Research Scanning Polarimeter (RSP). RSP provided intensity and degree of linear polarization over a broad spectral and angular range enabling column-average retrievals of aerosol optical and microphysical properties. Under this project, we analyzed observations and model results from RACORO, CARES, and CalNex and accomplished the following objectives. 1. Identified aerosol types, characterize the vertical distribution of the aerosol types, and partition aerosol optical depth by type, for CARES and CalNex using HSRL data as we have done for previous missions. 2. Investigated aerosol microphysical and macrophysical properties using the RSP. 3. Used the aerosol backscatter and extinction profiles measured by the HSRL

  6. The surface aerosol optical properties in the urban area of Nanjing, west Yangtze River Delta, China

    NASA Astrophysics Data System (ADS)

    Zhuang, Bingliang; Wang, Tijian; Liu, Jane; Li, Shu; Xie, Min; Han, Yong; Chen, Pulong; Hu, Qiduo; Yang, Xiu-qun; Fu, Congbin; Zhu, Jialei

    2017-01-01

    Observational studies of aerosol optical properties are useful for reducing uncertainties in estimations of aerosol radiative forcing and forecasting visibility. In this study, the observed near-surface aerosol optical properties in urban Nanjing are analysed from March 2014 to February 2016. Results show that near-surface urban aerosols in Nanjing are mainly from local emissions and the surrounding regions. They have lower loadings but are more scattering than aerosols in most cities in China. The annual mean aerosol extinction coefficient (EC), single-scattering albedo (SSA) and asymmetry parameter (ASP) at 550 nm are 381.96 Mm-1, 0.9 and 0.57, respectively. The aerosol absorption coefficient (AAC) is about 1 order of magnitude smaller than its scattering coefficient (SC). However, the absorbing aerosol has a larger Ångström exponent (AAE) value, 1.58 at 470/660 nm, about 0.2 larger than the scattering aerosols (SAE). All the aerosol optical properties follow a near-unimodal pattern, and their values are mostly concentrated around their averages, accounting for more than 60 % of the total samplings. Additionally, they have substantial seasonality and diurnal variations. High levels of SC and AAC all appear in winter due to higher aerosol and trace gas emissions. AAE (ASP) is the smallest (largest) in summer, possibly because of high relative humidity (RH) which also causes considerably larger SC and smaller SAE, although intensive gas-to-particle transformation could produce a large number of finer scattering aerosols in this season. Seasonality of EC is different from the columnar aerosol optical depth. Larger AACs appear during the rush hours of the day while SC and back-scattering coefficient (Bsp) only peak in the early morning. Aerosols are fresher in the daytime than at night-time, leading to their larger Ångström exponent and smaller ASP. Different temporal variations between AAC and SC cause the aerosols to be more absorbing (smaller SSA) in autumn

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

    NASA Astrophysics Data System (ADS)

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

    2009-12-01

    The Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite, a joint US and French mission, was launched three years ago to provide new insight into the role that clouds and aerosols play in regulating Earth's weather, climate, and air quality. A key instrument on board the CALIPSO payload is a two-wavelength, polarization-sensitive backscatter lidar. With its capabilities of depolarization ratio measurement and high resolution profiling, the CALIPSO lidar provides a unique opportunity to study the dust aerosol globally. Currently, a cloud and aerosol discrimination (CAD) algorithm that incorporates five-dimensional probability distribution function (5D-PDF) is being developed for implementation in future data releases. This new 5D-PDF approach allows nearly unambiguous identification of dense dust layers over/near their source regions and therefore enables the study of these layers using a large amount of the CALIPSO data. Lidar ratio (i.e., extinction-to-backscatter ratio) is an intrinsic optical property of aerosols and a key parameter necessary in the lidar signal inversion to retrieve profiles of aerosol extinction and backscatter coefficients, which are two primary products of the CALIPSO level 2 data. This parameter is usually selected in the CALIPSO lidar level 2 data processing based on the aerosol type identified. (Six types of aerosols have been modeled: dust, polluted dust, marine, continental, polluted continental, and smoke.) As more data is being collected by the CALIPSO lidar, validation studies with the CALIPSO measurements are being performed and are now becoming available. For opaque dust layers, the effective lidar ratio (the product of lidar ratio and multiple scattering factor) can be determined easily from integrated attenuated backscatter over the layer top and apparent base. We have performed an extensive analysis based on the first two and a half years (June 2006 - December 2008) of the CALIPSO lidar nighttime

  8. Column Closure Studies of Lower Tropospheric Aerosol and Water Vapor During ACE-Asia Using Airborne Sunphotometer, Airborne In-Situ and Ship-Based Lidar Measurements

    NASA Technical Reports Server (NTRS)

    Schmid, B.; Hegg, A.; Wang, J.; Bates, D.; Redemann, J.; Russells, P. B.; Livingston, J. M.; Jonsson, H. H.; Welton, E. J.; Seinfield, J. H.

    2003-01-01

    We assess the consistency (closure) between solar beam attenuation by aerosols and water vapor measured by airborne sunphotometry and derived from airborne in-situ, and ship-based lidar measurements during the April 2001 Asian Pacific Regional Aerosol Characterization Experiment (ACE-Asia). The airborne data presented here were obtained aboard the Twin Otter aircraft. Comparing aerosol extinction o(550 nm) from four different techniques shows good agreement for the vertical distribution of aerosol layers. However, the level of agreement in absolute magnitude of the derived aerosol extinction varied among the aerosol layers sampled. The sigma(550 nm) computed from airborne in-situ size distribution and composition measurements shows good agreement with airborne sunphotometry in the marine boundary layer but is considerably lower in layers dominated by dust if the particles are assumed to be spherical. The sigma(550 nm) from airborne in-situ scattering and absorption measurements are about approx. 13% lower than those obtained from airborne sunphotometry during 14 vertical profiles. Combining lidar and the airborne sunphotometer measurements reveals the prevalence of dust layers at altitudes up to 10 km with layer aerosol optical depth (from 3.5 to 10 km altitude) of approx. 0.1 to 0.2 (500 nm) and extinction-to-backscatter ratios of 59-71 sr (523 nm). The airborne sunphotometer aboard the Twin Otter reveals a relatively dry atmosphere during ACE- Asia with all water vapor columns less than 1.5 cm and water vapor densities w less than 12 g/cu m. Comparing layer water vapor amounts and w from the airborne sunphotometer to the same quantities measured with aircraft in-situ sensors leads to a high correlation (r(sup 3)=0.96) but the sunphotometer tends to underestimate w by 7%.

  9. SAGE Aerosol Measurements. Volume 2: 1 January - 31 December 1980

    NASA Technical Reports Server (NTRS)

    Mccormick, M. P.

    1986-01-01

    The stratospheric Aerosol and Gas Experiment (SAGE) satellite system, launched on February 18, 1979, provides profiles of aerosol extinction at wavelengths of 1.00 and 0.45 micron, ozone concentration, and nitrogen dioxide concentration. Data taken during sunset events in the form of zonal averages and seasonal averages of the aerosol extinction at 1.00 and 0.45 micron, ratios of the aerosol extinction to the molecular extinction at 1.00 micron, and ratios of the aerosol extinction at 0.45 micron to the aerosol extinction at 1.00 micron are presented. The averages for l980 are shown in tables and in profile and contour plots (as a function of altitude and latitude). In addition, temperature data provided by the National Oceanic and Atmospheric Administration (NOAA) for the time and location of each SAGE measurement are averaged and shown in a similar format.

  10. VizieR Online Data Catalog: Atmospheric extinction properties above Mauna Kea (Buton+, 2013)

    NASA Astrophysics Data System (ADS)

    Buton, C.; Copin, Y.; Aldering, G.; Antilogus, P.; Aragon, C.; Bailey, S.; Baltay, C.; Bongard, S.; Canto, A.; Cellier-Holzem, F.; Childress, M.; Chotard, N.; Fakhouri, H. K.; Gangler, E.; Guy, J.; Hsiao, E. Y.; Kerschhaggl, M.; Kowalski, M.; Loken, S.; Nugent, P.; Paech, K.; Pain, R.; Pecontal, E.; Pereira, R.; Perlmutter, S.; Rabinowitz, D.; Rigault, M.; Runge, K.; Scalzo, R.; Smadja, G.; Tao, C.; Thomas, R. C.; Weaver, B. A.; Wu, C.; Nearby Supernova Factory

    2012-10-01

    SNfactory median atmospheric extinction [mag/airmass] and its decomposition into physical components (Ozone, Aerosol optical depth and Aerosol Angstroem exponent) from 3200Å to 10000Å (2Å bins). (2 data files).

  11. MPL-Net Measurements of Aerosol and Cloud Vertical Distributions at Co-Located AERONET Sites

    NASA Technical Reports Server (NTRS)

    Welton, Ellsworth J.; Campbell, James R.; Berkoff, Timothy A.; Spinhirne, James D.; Tsay, Si-Chee; Holben, Brent; Starr, David OC. (Technical Monitor)

    2002-01-01

    In the early 1990s, the first small, eye-safe, and autonomous lidar system was developed, the Micropulse Lidar (MPL). The MPL acquires signal profiles of backscattered laser light from aerosols and clouds. The signals are analyzed to yield multiple layer heights, optical depths of each layer, average extinction-to-backscatter ratios for each layer, and profiles of extinction in each layer. In 2000, several MPL sites were organized into a coordinated network, called MPL-Net, by the Cloud and Aerosol Lidar Group at NASA Goddard Space Flight Center (GSFC) using funding provided by the NASA Earth Observing System. tn addition to the funding provided by NASA EOS, the NASA CERES Ground Validation Group supplied four MPL systems to the project, and the NASA TOMS group contributed their MPL for work at GSFC. The Atmospheric Radiation Measurement Program (ARM) also agreed to make their data available to the MPL-Net project for processing. In addition to the initial NASA and ARM operated sites, several other independent research groups have also expressed interest in joining the network using their own instruments. Finally, a limited amount of EOS funding was set aside to participate in various field experiments each year. The NASA Sensor Intercomparison and Merger for Biological and Interdisciplinary Oceanic Studies (SIMBIOS) project also provides funds to deploy their MPL during ocean research cruises. All together, the MPL-Net project has participated in four major field experiments since 2000. Most MPL-Net sites and field experiment locations are also co-located with sunphotometers in the NASA Aerosol Robotic Network. (AERONET). Therefore, at these locations data is collected on both aerosol and cloud vertical structure as well as column optical depth and sky radiance. Real-time data products are now available from most MPL-Net sites. Our real-time products are generated at times of AERONET aerosol optical depth (AOD) measurements. The AERONET AOD is used as input to our

  12. Nature, Origin, Potential Composition, and Climate Impact of the Asian Tropopause Aerosol Layer (ATAL)

    NASA Technical Reports Server (NTRS)

    Fairlie, T. D.; Vernier, J.-P.; Thomason, L. W.; Natarajan, M.; Bedka, K.; Wienhold, F.; Bian J.; Martinsson, B.

    2015-01-01

    Satellite observations from SAGE II and CALIPSO indicate that summertime aerosol extinction has more than doubled in the Asian Tropopause Aerosol Layer (ATAL) since the late 1990s. Here we show remote and in-situ observations, together with results from a chemical transport model (CTM), to explore the likely composition, origin, and radiative forcing of the ATAL. We show in-situ balloon measurements of aerosol backscatter, which support the high levels observed by CALIPSO since 2006. We also show in situ measurements from aircraft, which indicate a predominant carbonaceous contribution to the ATAL (Carbon/Sulfur ratios of 2- 10), which is supported by the CTM results. We show that the peak in ATAL aerosol lags by 1 month the peak in CO from MLS, associated with deep convection over Asia during the summer monsoon. This suggests that secondary formation and growth of aerosols in the upper troposphere on monthly timescales make a significant contribution to ATAL. Back trajectory calculations initialized from CALIPSO observations provide evidence that deep convection over India is a significant source for ATAL through the vertical transport of pollution to the upper troposphere.

  13. Aerosol detection methods in lidar-based atmospheric profiling

    NASA Astrophysics Data System (ADS)

    Elbakary, Mohamed I.; Iftekharuddin, Khan M.; De Young, Russell; Afrifa, Kwasi

    2016-09-01

    A compact light detection and ranging (LiDAR) system provides aerosols profile measurements by identifying the aerosol scattering ratio as function of the altitude. The aerosol scattering ratios are used to obtain multiple aerosol intensive ratio parameters known as backscatter color ratio, depolarization ratio and lidar ratio. The aerosol ratio parameters are known to vary with aerosol type, size, and shape. Different methods in the literature are employed for detection and classification of aerosol from the measurements. In this paper, a comprehensive review for aerosol detection methods is presented. In addition, results of implemented methods of quantifying aerosols in the atmosphere on real data are compared and presented showing how the backscatter color, depolarization and lidar ratios vary with presence of aerosols in the atmosphere.

  14. Extinctions of life

    NASA Technical Reports Server (NTRS)

    Sepkoski, J. J. Jr; Sepkoski JJ, J. r. (Principal Investigator)

    1988-01-01

    This meeting presentation examines mass extinctions through earth's history. Extinctions are charted for marine families and marine genera. Timing of marine genera extinctions is discussed. Periodicity in extinctions during the Mesozoic and Cenozoic eras is plotted and compared with Paleozoic extinction peaks. The role of extinction in evolution and mankind's role in present extinctions are examined.

  15. Quantitative retrieval of aerosol optical properties by means of ceilometers

    NASA Astrophysics Data System (ADS)

    Wiegner, Matthias; Gasteiger, Josef; Geiß, Alexander

    2016-04-01

    In the last few years extended networks of ceilometers have been established by several national weather services. Based on improvements of the hardware performance of these single-wavelength backscatter lidars and their 24/7 availability they are increasingly used to monitor mixing layer heights and to derive profiles of the particle backscatter profile. As a consequence they are used for a wide range of applications including the dispersion of volcanic ash plumes, validation of chemistry transport models and air quality studies. In this context the development of automated schemes to detect aerosol layers and to identify the mixing layer are essential, in particular as the latter is often used as a proxy for air quality. Of equal importance is the calibration of ceilometer signals as a pre-requisite to derive quantitative optical properties. Recently, it has been emphasized that the majority of ceilometers are influenced by water vapor absorption as they operate in the spectral range of 905 - 910 nm. If this effect is ignored, errors of the aerosol backscatter coefficient can be as large as 50%, depending on the atmospheric water vapor content and the emitted wavelength spectrum. As a consequence, any other derived quantity, e.g. the extinction coefficient or mass concentration, would suffer from a significant uncertainty in addition to the inherent errors of the inversion of the lidar equation itself. This can be crucial when ceilometer derived profiles shall be used to validate transport models. In this presentation, the methodology proposed by Wiegner and Gasteiger (2015) to correct for water vapor absorption is introduced and discussed.

  16. Development of a global model for atmospheric backscatter at CO2 wavelengths

    NASA Technical Reports Server (NTRS)

    Kent, G. S.; Wang, P. H.; Farrukh, U.; Deepak, A.; Patterson, E. M.

    1986-01-01

    The variation of the aerosol backscattering at 10.6 micrometers within the free troposphere was investigated and a model to describe this variation was developed. The analysis combines theoretical modeling with the results contained within three independent data sets. The data sets used were obtained by the SAGE I/SAM II satellite experiments, the GAMETAG flight series, and by direct backscatter measurements. The theoretical work includes use of a bimodal, two component aerosol model, and the study of the microphysical and associated optical changes occurring within an aerosol plume. A consistent picture is obtained that describes the variation of the aerosol backscattering function in the free troposphere with altitude, latitude, and season.

  17. Development of global model for atmospheric backscatter at CO2 wavelengths

    NASA Technical Reports Server (NTRS)

    Kent, G. S.; Wang, P. H.; Farrukh, U.; Deepak, A.; Patterson, E. M.

    1985-01-01

    The improvement of an understanding of the variation of the aerosol backscattering at 10.6 micron within the free troposphere and the development model to describe this was undertaken. The analysis combines theoretical modeling with the results contained within three independent data sets. The data sets are obtained by the SAGE I/SAM II satellite experiments, the GAMETAG flight series and by direct backscatter measurements. The theoretical work includes use of a bimodal, two component aerosol model, and the study of the microphysical and associated optical changes occurring within an aerosol plume. A consistent picture is obtained, which describes the variation of the aerosol backscattering function in the free troposphere with altitude, latitude, and season. Most data are available and greatest consistency is found inside the Northern Hemisphere.

  18. Use of active and passive ground based remote sensors to explore cloud droplet modifications in aerosol-cloud interactions

    NASA Astrophysics Data System (ADS)

    Han, Zaw Thet

    We explore the potential aerosol impact on cloud optical properties which is a strong modifier of climate forcing. Previous studies have shown that increased aerosol loading can affect the cloud optical properties such as cloud optical depth and cloud droplet effective radius in rural areas, particularly at the Atmospheric Radiation Measurement, Southern Great Plain site. In this study, we attempt to observe and quantify aerosol-cloud interaction over New York City, using a combination of passive and active radiometric sensors. In particular, we look for signatures of the Twomey indirect effect which states that the droplet size of water phase clouds will decrease with increasing aerosols. We find that under certain conditions, a strong signature is found between the cloud drop effective radius and extinction and this effect is in part due to vertical wind uptake. In demonstrating the Aerosol Cloud Interaction, we use multiple approaches. For example, we derive the integrated liquid water path using both a multiband neural network and dual channel approach and show general agreement between two methods while the DC approach seems more robust. We also find that these measurements are difficult and sensitive to the position of the aerosols relative to the cloud base. As a corollary, we explore whether near surface aerosol loading can effecting the cloud by using particulate matter (PM2.5) and find that the effects are too variable to be given any statistical weight. Finally, we explore the potential of modifying our approach to remove the noisy and difficult measurement of Raman LIDAR derived extinction with calibrated LIDAR backscatter. The results seem to show a general improvement in correlation and offer the possibility of increasing the number of cases observed.

  19. Classification of Aerosol Retrievals from Spaceborne Polarimetry Using a Multi-Parameter Algorithm

    NASA Astrophysics Data System (ADS)

    Russell, P. B.; Kacenelenbogen, M. S.; Livingston, J. M.; Hasekamp, O.; Burton, S. P.; Schuster, G. L.; Redemann, J.; Ramachandran, S.; Holben, B. N.

    2013-12-01

    In this presentation we demonstrate application of a new aerosol classification algorithm to retrievals from the POLDER-3 polarimeter on the PARASOL spacecraft. Motivation and method: Since the development of global aerosol measurements by satellites and AERONET, classification of observed aerosols into several types (e,g., urban-industrial, biomass burning, mineral dust, maritime, and various subtypes or mixtures of these) has proven useful to: understanding aerosol sources, transformations, effects, and feedback mechanisms; improving accuracy of satellite retrievals; and quantifying assessments of aerosol radiative impacts on climate. With ongoing improvements in satellite measurement capability, the number of aerosol parameters retrieved from spaceborne sensors has been growing, from the initial aerosol optical depth at one or a few wavelengths to a list that now includes complex refractive index, single scattering albedo (SSA), and depolarization of backscatter, each at several wavelengths; wavelength dependences of extinction, scattering, absorption, SSA, and backscatter; and several particle size and shape parameters. Making optimal use of these varied data products requires objective, multi-dimensional analysis methods. We describe such a method, which uses a modified Mahalanobis distance to quantify how far a data point described by N aerosol parameters is from each of several prespecified classes. The method makes explicit use of uncertainties in input parameters, treating a point and its N-dimensional uncertainty as an extended data point or pseudo-cluster E. It then uses a modified Mahalanobis distance, DEC, to assign that observation to the class (cluster) C that has minimum DEC from the point (equivalently, the class to which the point has maximum probability of belonging). The method also uses Wilks' overall lambda to indicate how well the input data lend themselves to separation into classes and Wilks' partial lambda to indicate the relative

  20. THERMAL NEUTRON BACKSCATTER IMAGING.

    SciTech Connect

    VANIER,P.; FORMAN,L.; HUNTER,S.; HARRIS,E.; SMITH,G.

    2004-10-16

    Objects of various shapes, with some appreciable hydrogen content, were exposed to fast neutrons from a pulsed D-T generator, resulting in a partially-moderated spectrum of backscattered neutrons. The thermal component of the backscatter was used to form images of the objects by means of a coded aperture thermal neutron imaging system. Timing signals from the neutron generator were used to gate the detection system so as to record only events consistent with thermal neutrons traveling the distance between the target and the detector. It was shown that this time-of-flight method provided a significant improvement in image contrast compared to counting all events detected by the position-sensitive {sup 3}He proportional chamber used in the imager. The technique may have application in the detection and shape-determination of land mines, particularly non-metallic types.

  1. Early-spring aerosol characterization across multiple Arctic stations

    NASA Astrophysics Data System (ADS)

    Baibakov, Konstantin; O'Neill, Norm; Ivanescu, Liviu; Perro, Chris; Ritter, Christoph; Herber, Andreas; Duck, Tom J.; Schulz, Karl-Heinz; Schrems, Otto

    2013-04-01

    The Arctic region is characterized by complex interactions between aerosols, clouds and precipitation. Ground-based observations of atmospheric optical properties are usually comprised of photometric aerosol optical depth (AOD) measurements and lidar extinction and backscatter profiles. The night-time AODs obtained with star- and moonphotometry have been extremely limited in the Arctic region. The first part of the paper is based on the synchronous starphotometry and lidar measurements obtained at Eureka (Canada, 80°N, 86°W) and Ny Alesund (Spitsbergen, 79°N, 12°E) in late winter-early spring periods of 2011 and 2012. We present several examples of process-level events as well as the winter to spring climatological dynamics of cloud-screened optical depths. The particular cases include aerosol, thin-cloud, ice crystals and polar stratospheric cloud events. An integral part of the process-level analysis, which ultimately informs the seasonal analysis, is the synergistic interpretation of the spectral, temporal and spatial information content of the passive and active data. In the second part of the paper we present the preliminary results obtained from the intercomparison field campaign at Barrow (Alaska, 71°N,156°W) that took place in spring 2013. The instrumentation suit included high-spectral resolution lidar, a starphotometer and a moonphotometer.

  2. Australian Extinctions

    ERIC Educational Resources Information Center

    Science Teacher, 2005

    2005-01-01

    Massive extinctions of animals and the arrival of the first humans in ancient Australia--which occurred 45,000 to 55,000 years ago--may be linked. Researchers at the Carnegie Institution, University of Colorado, Australian National University, and Bates College believe that massive fires set by the first humans may have altered the ecosystem of…

  3. Identification of aerosol composition from multi-wavelength lidar measurements

    NASA Technical Reports Server (NTRS)

    Wood, S. A.

    1984-01-01

    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.

  4. Aerosol/Cloud Measurements Using Coherent Wind Doppler Lidars

    NASA Astrophysics Data System (ADS)

    Royer, Philippe; Boquet, Matthieu; Cariou, Jean-Pierre; Sauvage, Laurent; Parmentier, Rémy

    2016-06-01

    The accurate localization and characterization of aerosol and cloud layers is crucial for climate studies (aerosol indirect effect), meteorology (Planetary Boundary Layer PBL height), site monitoring (industrial emissions, mining,…) and natural hazards (thunderstorms, volcanic eruptions). LEOSPHERE has recently developed aerosol/cloud detection and characterization on WINDCUBE long range Coherent Wind Doppler Lidars (CWDL). These new features combine wind and backscatter intensity informations (Carrier-to-Noise Ratio CNR) in order to detect (aerosol/cloud base and top, PBL height) and to characterize atmospheric structures (attenuated backscatter, depolarization ratio). For each aerosol/cloud functionality the method is described, limitations are discussed and examples are given to illustrate the performances.

  5. Visibility related to backscatter at 1.54 micron

    NASA Technical Reports Server (NTRS)

    Barber, T. L.; Larson, D. R.

    1986-01-01

    The lidar process was shown to have the necessary potential to fulfill the need for a remote measurement of visibility. Visibility can be inferred from a lidar return optical extinction. The wavelength 1.54 micron was chosen, being near the visible wavelength region and having a high eye safety threshol, 200,000 times higher than 1.06 micron; 1.54 is the erbium laser wavelength. This research utilized 105 measured height profiles of natural droplet size distributions data, taken in clouds, fog, and haze. These profiles were examined to determine the completeness of the droplet counting data. It was found that the particle spectrometer data were incomplete in the very light ford and haze so this portion of the data was eliminated. Utilizing the Mie theory, these droplet size distribution profiles were converted to backscatter at 1.54 micron and extinction in the visible region, 0.55 micron. Using Koschmeider's relationship, the extinction profiles were converted to visibility. The visibility and backscatter profiles were compared to develop a relationship between visibility and backscatter at 1.54 micron.

  6. Measuring black carbon spectral extinction in the visible and infrared

    NASA Astrophysics Data System (ADS)

    Smith, A. J. A.; Peters, D. M.; McPheat, R.; Lukanihins, S.; Grainger, R. G.

    2015-09-01

    This work presents measurements of the spectral extinction of black carbon aerosol from 400 nm to 15 μm. The aerosol was generated using a Miniature Combustion Aerosol Standard soot generator and then allowed to circulate in an aerosol cell where its extinction was measured using a grating spectrometer in the visible and a Fourier transform spectrometer in the infrared. Size distribution, number concentration, and mass extinction cross sections have also been obtained using single-particle aerosol samplers. A mean mass extinction cross section at 550 nm of 8.3 ± 1.6 m2 g-1 is found which, assuming a reasonable single scatter albedo of 0.2, corresponds to a mass absorption cross section of 6.6 ± 1.3 m2 g-1. This compares well with previously reported literature values. Computer analysis of electron microscope images of the particles provides independent confirmation of the size distribution as well as fractal parameters of the black carbon aerosol. The aerosol properties presented in this work are representative of very fresh, uncoated black carbon aerosol. After atmospheric processing of such aerosols (which could include mixing with other constituents and structural changes), different optical properties would be expected.

  7. Optical properties of mixed aerosol layers over Japan derived with multi-wavelength Mie-Raman lidar system

    NASA Astrophysics Data System (ADS)

    Hara, Yukari; Nishizawa, Tomoaki; Sugimoto, Nobuo; Matsui, Ichiro; Pan, Xiaole; Kobayashi, Hiroshi; Osada, Kazuo; Uno, Itsushi

    2017-02-01

    Mixing state of aerosols and optical properties including lidar ratio, particle depolarization ratio, and Ångström exponent were investigated at Fukuoka in western Japan using a multi-wavelength Mie-Raman lidar (MMRL), various aerosol mass-concentration measurements, and a polarization optical particle counter during Winter-Spring 2015. Aerosol extinction coefficient, backscatter coefficient, and depolarization at 355 and 532 nm and attenuated backscatter coefficient at 1064 nm are obtained from the MMRL measurements. Ten aerosol episodes were classified into three categories (air pollution, mineral dust, and marine aerosol) based on aerosol mass-concentration measurements in the fine-mode (particle diameter Dp<2.5 μm) and coarse-mode (2.5 μmaerosols. The lowest lidar ratio was obtained for marine case. Classification of aerosol types using the lidar ratio and particle depolarization ratio was conducted based on the results obtained in this study. The classified aerosol types almost corresponded to aerosol category obtained by previous studies. We found no remarkable correlation between the fraction of black carbon and the lidar ratio: this might be due to the complexity of the mixing state among various aerosols. The obtained lidar ratio was rather correlated with the ratio of PMf to PM10, representing the mixing state of fine- and coarse-mode particles.

  8. Dust aerosol emission over the Sahara during summertime from Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) observations

    NASA Astrophysics Data System (ADS)

    Todd, Martin C.; Cavazos-Guerra, Carolina

    2016-03-01

    Dust aerosols are an important component of the climate system and a challenge to incorporate into weather and climate models. Information on the location and magnitude of dust emission remains a key information gap to inform model development. Inadequate surface observations ensure that satellite data remain the primary source of this information over extensive and remote desert regions. Here, we develop estimates of the relative magnitude of active dust emission over the Sahara desert based on data from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP). Utilising the unique vertical profile of aerosol characteristics provided by CALIOP our algorithm identifies emission from aerosol extinction and lidar backscatter in the near surface layers. From the long-term CALIOP archive of day and night-time orbits over 2006-13 we construct coarse resolution maps of a new dust emission index (DEI) for the Sahara desert during the peak summer dust season (June to September). The spatial structure of DEI indicates highest emission over a broad zone focused on the border regions of Southern Algeria, Northern Mali and northwest Niger, displaced substantially (∼7°) to the east of the mean maximum in satellite-derived aerosol optical depth. In this region night-time emission exceeds that during the day. The DEI maps substantially corroborate recently derived dust source frequency count maps based on back-tracking plumes in high temporal resolution SEVIRI imagery. As such, a convergence of evidence from multiple satellite data sources using independent methods provides an increasingly robust picture of Saharan dust emission sources. Various caveats are considered. As such, quantitative estimates of dust emission may require a synergistic combined multi-sensor analysis.

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

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

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

  10. Temporal consistency of lidar observables during aerosol transport events in the framework of the ChArMEx/ADRIMED campaign at Menorca Island in June 2013

    NASA Astrophysics Data System (ADS)

    Chazette, P.; Totems, J.; Ancellet, G.; Pelon, J.; Sicard, M.

    2015-11-01

    We performed synergetic daytime and night-time active and passive remote sensing observations at Menorca (Balearic Island, Spain), over more than 3 weeks during the Chemistry-Aerosol Mediterranean Experiment/Aerosol Direct Radiative Effect in the Mediterranean (ChArMEx/ADRIMED) special observation period (SOP 1a, June-July 2013). We characterized the aerosol optical properties and type in the low and middle troposphere using an automated procedure combining Rayleigh-Mie-Raman lidar (355, 387 and 407 nm) with depolarization (355 nm) and AERONET Cimel® sun-photometer data. Results show a high variability due to varying dynamical forcing. The mean column-averaged lidar backscatter-to-extinction ratio (BER) was close to 0.024 sr-1 (lidar ratio of ∼ 41.7 sr), with a large dispersion of ±33 % over the whole observation period due to changing atmospheric transport regimes and aerosol sources. The ground-based remote sensing measurements, coupled with satellite observations, allowed to document (i) dust particles up to 5 km a.s.l. in altitude originating from Morocco and Algeria from 15 to 18 June with a peak in aerosol optical thickness (AOT) of 0.25 ± 0.05 at 355 nm, (ii) a long-range transport of biomass burning aerosol (AOT = 0.18 ± 0.16) related to North American forest fires detected from 26 to 28 June 2013 by the lidar between 2 and 7 km and (iii) mixture of local sources including marine aerosol particles and pollution from Spain. During the biomass burning event, the high value of the particle depolarization ratio (8-14 %) may imply the presence of dust-like particles mixed with the biomass burning aerosols in the mid troposphere. We show also linearity with SEVIRI retrievals of the aerosol optical thickness within 35 % relative bias, which is discussed as a function of aerosol type.

  11. Temporal consistency of lidar observations during aerosol transport events in the framework of the ChArMEx/ADRIMED campaign at Minorca in June 2013

    NASA Astrophysics Data System (ADS)

    Chazette, Patrick; Totems, Julien; Ancellet, Gérard; Pelon, Jacques; Sicard, Michaël

    2016-03-01

    We performed synergetic daytime and nighttime active and passive remote-sensing observations at Minorca (Balearic Islands, Spain), over more than 3 weeks during the Chemistry-Aerosol Mediterranean Experiment/Aerosol Direct Radiative Effect in the Mediterranean (ChArMEx/ADRIMED) special observation period (SOP 1a, June-July 2013). We characterized the aerosol optical properties and type in the low and middle troposphere using an automated procedure combining Rayleigh-Mie-Raman lidar (355, 387 and 407 nm) with depolarization (355 nm) and AERONET Cimel® sun-photometer data. Results show a high variability due to varying dynamical forcing. The mean column-averaged lidar backscatter-to-extinction ratio (BER) was close to 0.024 sr-1 (lidar ratio of ˜ 41.7 sr), with a large dispersion of ±33 % over the whole observation period due to changing atmospheric transport regimes and aerosol sources. The ground-based remote-sensing measurements, coupled with satellite observations, allowed the documentation of (i) dust particles up to 5 km (above sea level) in altitude originating from Morocco and Algeria from 15 to 18 June with a peak in aerosol optical thickness (AOT) of 0.25 ± 0.05 at 355 nm, (ii) a long-range transport of biomass burning aerosol (AOT = 0.18 ± 0.16) related to North American forest fires detected from 26 to 28 June 2013 by the lidar between 2 and 7 km and (iii) mixture of local sources including marine aerosol particles and pollution from Spain. During the biomass burning event, the high value of the particle depolarization ratio (8-14 %) may imply the presence of dust-like particles mixed with the biomass burning aerosols in the mid-troposphere. For the field campaign period, we also show linearity with SEVIRI retrievals of the aerosol optical thickness despite 35 % relative bias, which is discussed as a function of aerosol type.

  12. Aerosol remote sensing in polar regions

    SciTech Connect

    Tomasi, Claudio; Kokhanovsky, Alexander A.; Lupi, Angelo; Ritter, Christoph; Smirnov, Alexander; O'Neill, Norman T.; Stone, Robert S.; Holben, Brent N.; Nyeki, Stephan; Mazzola, Mauro; Lanconelli, Christian; Vitale, Vito; Stebel, Kerstin; Aaltonen, Veijo; de Leeuw, Gerrit; Rodriguez, Edith; Herber, Andreas B.; Radionov, Vladimir F.; Zielinski, Tymon; Petelski, Tomasz; Sakerin, Sergey M.; Kabanov, Dmitry M.; Xue, Yong; Mei, Linlu; Istomina, Larysa; Wagener, Richard; McArthur, Bruce; Sobolewski, Piotr S.; Kivi, Rigel; Courcoux, Yann; Larouche, Pierre; Broccardo, Stephen; Piketh, Stuart J.

    2015-01-01

    Multi-year sets of ground-based sun-photometer measurements conducted at 12 Arctic sites and 9 Antarctic sites were examined to determine daily mean values of aerosol optical thickness τ(λ) at visible and near-infrared wavelengths, from which best-fit values of Ångström's exponent α were calculated. Analysing these data, the monthly mean values of τ(0.50 μm) and α and the relative frequency histograms of the daily mean values of both parameters were determined for winter–spring and summer–autumn in the Arctic and for austral summer in Antarctica. The Arctic and Antarctic covariance plots of the seasonal median values of α versus τ(0.50 μm) showed: (i) a considerable increase in τ(0.50 μm) for the Arctic aerosol from summer to winter–spring, without marked changes in α; and (ii) a marked increase in τ(0.50 μm) passing from the Antarctic Plateau to coastal sites, whereas α decreased considerably due to the larger fraction of sea-salt aerosol. Good agreement was found when comparing ground-based sun-photometer measurements of τ(λ) and α at Arctic and Antarctic coastal sites with Microtops measurements conducted during numerous AERONET/MAN cruises from 2006 to 2013 in three Arctic Ocean sectors and in coastal and off-shore regions of the Southern Atlantic, Pacific, and Indian Oceans, and the Antarctic Peninsula. Lidar measurements were also examined to characterise vertical profiles of the aerosol backscattering coefficient measured throughout the year at Ny-Ålesund. Satellite-based MODIS, MISR, and AATSR retrievals of τ(λ) over large parts of the oceanic polar regions during spring and summer were in close agreement with ship-borne and coastal ground-based sun-photometer measurements. An overview of the chemical composition of mode particles is also presented, based on in-situ measurements at Arctic and Antarctic sites. Fourteen log-normal aerosol number size-distributions were defined to represent the average features of nuclei

  13. Aerosol remote sensing in polar regions

    DOE PAGES

    Tomasi, Claudio; Kokhanovsky, Alexander A.; Lupi, Angelo; ...

    2015-01-01

    Multi-year sets of ground-based sun-photometer measurements conducted at 12 Arctic sites and 9 Antarctic sites were examined to determine daily mean values of aerosol optical thickness τ(λ) at visible and near-infrared wavelengths, from which best-fit values of Ångström's exponent α were calculated. Analysing these data, the monthly mean values of τ(0.50 μm) and α and the relative frequency histograms of the daily mean values of both parameters were determined for winter–spring and summer–autumn in the Arctic and for austral summer in Antarctica. The Arctic and Antarctic covariance plots of the seasonal median values of α versus τ(0.50 μm) showed: (i)more » a considerable increase in τ(0.50 μm) for the Arctic aerosol from summer to winter–spring, without marked changes in α; and (ii) a marked increase in τ(0.50 μm) passing from the Antarctic Plateau to coastal sites, whereas α decreased considerably due to the larger fraction of sea-salt aerosol. Good agreement was found when comparing ground-based sun-photometer measurements of τ(λ) and α at Arctic and Antarctic coastal sites with Microtops measurements conducted during numerous AERONET/MAN cruises from 2006 to 2013 in three Arctic Ocean sectors and in coastal and off-shore regions of the Southern Atlantic, Pacific, and Indian Oceans, and the Antarctic Peninsula. Lidar measurements were also examined to characterise vertical profiles of the aerosol backscattering coefficient measured throughout the year at Ny-Ålesund. Satellite-based MODIS, MISR, and AATSR retrievals of τ(λ) over large parts of the oceanic polar regions during spring and summer were in close agreement with ship-borne and coastal ground-based sun-photometer measurements. An overview of the chemical composition of mode particles is also presented, based on in-situ measurements at Arctic and Antarctic sites. Fourteen log-normal aerosol number size-distributions were defined to represent the average features of nuclei

  14. Aerosol Remote Sensing in Polar Regions

    NASA Technical Reports Server (NTRS)

    Tomasi, Claudio; Kokhanovsky, Alexander A.; Lupi, Angelo; Ritter, Christoph; Smirnov, Alexander; O'Neill, Norman T.; Stone, Robert S.; Holben, Brent N.; Nyeki, Stephan; Wehrli, Christoph

    2014-01-01

    Multi-year sets of ground-based sun-photometer measurements conducted at 12 Arctic sites and 9 Antarctic sites were examined to determine daily mean values of aerosol optical thickness tau(lambda) at visible and near-infrared wavelengths, from which best-fit values of Ångström's exponent alpha were calculated. Analyzing these data, the monthly mean values of tau(0.50 micrometers) and alpha and the relative frequency histograms of the daily mean values of both parameters were determined for winter-spring and summer-autumn in the Arctic and for austral summer in Antarctica. The Arctic and Antarctic covariance plots of the seasonal median values of alpha versus tau(0.50 micrometers) showed: (i) a considerable increase in tau(0.50 micrometers) for the Arctic aerosol from summer to winter-spring, without marked changes in alpha; and (ii) a marked increase in tau(0.50 micrometer) passing from the Antarctic Plateau to coastal sites, whereas alpha decreased considerably due to the larger fraction of sea-salt aerosol. Good agreement was found when comparing ground-based sun-photometer measurements of tau(lambda) and alpha at Arctic and Antarctic coastal sites with Microtops measurements conducted during numerous AERONET/MAN cruises from 2006 to 2013 in three Arctic Ocean sectors and in coastal and off-shore regions of the Southern Atlantic, Pacific, and Indian Oceans, and the Antarctic Peninsula. Lidar measurements were also examined to characterize vertical profiles of the aerosol backscattering coefficient measured throughout the year at Ny-Ålesund. Satellite-based MODIS, MISR, and AATSR retrievals of tau(lambda) over large parts of the oceanic polar regions during spring and summer were in close agreement with ship-borne and coastal ground-based sun-photometer measurements. An overview of the chemical composition of mode particles is also presented, based on in-situ measurements at Arctic and Antarctic sites. Fourteen log-normal aerosol number size-distributions were

  15. Measurement of size-dependent single scattering albedo of fresh biomass burning aerosols using the extinction-minus-scattering technique with a combination of cavity ring-down spectroscopy and nephelometry

    NASA Astrophysics Data System (ADS)

    Singh, Sujeeta; Fiddler, Marc N.; Bililign, Solomon

    2016-11-01

    Biomass burning (BB) aerosols have a significant effect on regional climate, and represent a significant uncertainty in our understanding of climate change. Using a combination of cavity ring-down spectroscopy and integrating nephelometry, the single scattering albedo (SSA) and Ångstrom absorption exponent (AAE) were measured for several North American biomass fuels. This was done for several particle diameters for the smoldering and flaming stage of white pine, red oak, and cedar combustion. Measurements were done over a wider wavelength range than any previous direct measurement of BB particles. While the offline sampling system used in this work shows promise, some changes in particle size distribution were observed, and a thorough evaluation of this method is required. The uncertainty of SSA was 6 %, with the truncation angle correction of the nephelometer being the largest contributor to error. While scattering and extinction did show wavelength dependence, SSA did not. SSA values ranged from 0.46 to 0.74, and were not uniformly greater for the smoldering stage than the flaming stage. SSA values changed with particle size, and not systematically so, suggesting the proportion of tar balls to fractal black carbon change with fuel type/state and particle size. SSA differences of 0.15-0.4 or greater can be attributed to fuel type or fuel state for fresh soot. AAE values were quite high (1.59-5.57), despite SSA being lower than is typically observed in wildfires. The SSA and AAE values in this work do not fit well with current schemes that relate these factors to the modified combustion efficiency of a burn. Combustion stage, particle size, fuel type, and fuel condition were found to have the most significant effects on the intrinsic optical properties of fresh soot, though additional factors influence aged soot.

  16. Optical and microphysical characterization of aerosol layers over South Africa by means of multi-wavelength depolarization and Raman lidar measurements

    NASA Astrophysics Data System (ADS)

    Giannakaki, Elina; van Zyl, Pieter G.; Müller, Detlef; Balis, Dimitris; Komppula, Mika

    2016-07-01

    Optical and microphysical properties of different aerosol types over South Africa measured with a multi-wavelength polarization Raman lidar are presented. This study could assist in bridging existing gaps relating to aerosol properties over South Africa, since limited long-term data of this type are available for this region. The observations were performed under the framework of the EUCAARI campaign in Elandsfontein. The multi-wavelength PollyXT Raman lidar system was used to determine vertical profiles of the aerosol optical properties, i.e. extinction and backscatter coefficients, Ångström exponents, lidar ratio and depolarization ratio. The mean microphysical aerosol properties, i.e. effective radius and single-scattering albedo, were retrieved with an advanced inversion algorithm. Clear differences were observed for the intensive optical properties of atmospheric layers of biomass burning and urban/industrial aerosols. Our results reveal a wide range of optical and microphysical parameters for biomass burning aerosols. This indicates probable mixing of biomass burning aerosols with desert dust particles, as well as the possible continuous influence of urban/industrial aerosol load in the region. The lidar ratio at 355 nm, the lidar ratio at 532 nm, the linear particle depolarization ratio at 355 nm and the extinction-related Ångström exponent from 355 to 532 nm were 52 ± 7 sr, 41 ± 13 sr, 0.9 ± 0.4 % and 2.3 ± 0.5, respectively, for urban/industrial aerosols, while these values were 92 ± 10 sr, 75 ± 14 sr, 3.2 ± 1.3 % and 1.7 ± 0.3, respectively, for biomass burning aerosol layers. Biomass burning particles are larger and slightly less absorbing compared to urban/industrial aerosols. The particle effective radius were found to be 0.10 ± 0.03, 0.17 ± 0.04 and 0.13 ± 0.03 µm for urban/industrial, biomass burning, and mixed aerosols, respectively, while the single-scattering albedo at 532 nm was 0.87 ± 0.06, 0.90 ± 0.06, and 0.88 ± 0.07 (at 532

  17. Optical and microphysical characterization of aerosol layers over South Africa by means of multi-wavelength depolarization and Raman lidar measurements

    NASA Astrophysics Data System (ADS)

    Giannakaki, E.; van Zyl, P. G.; Müller, D.; Balis, D.; Komppula, M.

    2015-12-01

    Optical and microphysical properties of different aerosol types over South Africa measured with a multi-wavelength polarization Raman lidar are presented. This study could assist in bridging existing gaps relating to aerosol properties over South Africa, since limited long-term data of this type is available for this region. The observations were performed under the framework of the EUCAARI campaign in Elandsfontein. The multi-wavelength PollyXT Raman lidar system was used to determine vertical profiles of the aerosol optical properties, i.e. extinction and backscatter coefficients, Ångström exponents, lidar ratio and depolarization ratio. The mean microphysical aerosol proper ties, i.e. effective radius and single scattering, albedo were retrieved with an advanced inversion algorithm. Clear differences were observed for the intensive optical properties of atmospheric layers of biomass burning and urban/industrial aerosols. Our results reveal a wide range of optical and microphysical parameters for biomass burning aerosols. This indicates probable mixing of biomass burning aerosols with desert dust particles, as well as the possible continuous influence of urban/industrial aerosol load in the region. The lidar ratio at 355 nm, the linear particle depolarization ratio at 355 nm and the extinction-related Ångström exponent from 355 to 532 nm were 52 ± 7 sr; 0.9 ± 0.4 % and 2.3 ± 0.5, respectively for urban/industrial aerosols, while these values were 92 ± 10 sr; 3.2 ± 1.3 %; 2.0 ± 0.4 respectively for biomass burning aerosols layers. Biomass burning particles are larger and slightly less absorbing compared to urban/industrial aerosols. The particle effective radius were found to be 0.10 ± 0.03, 0.17 ± 0.04 and 0.13 ± 0.03 μm for urban/industrial, biomass burning, and mixed biomass burning and desert dust aerosols, respectively, while the single scattering albedo at 532 nm were 0.87 ± 0.06, 0.90 ± 0.06, and 0.88 ± 0.07 (at 532 nm), respectively for

  18. Lidar Measurements of the Vertical Distribution of Aerosol Optical and Physical Properties over Central Asia

    DOE PAGES

    Chen, Boris B.; Sverdlik, Leonid G.; Imashev, Sanjar A.; ...

    2013-01-01

    The vertical structure of aerosol optical and physical properties was measured by Lidar in Eastern Kyrgyzstan, Central Asia, from June 2008 to May 2009. Lidar measurements were supplemented with surface-based measurements of PM 2.5 and PM 10 mass and chemical composition in both size fractions. Dust transported into the region is common, being detected 33% of the time. The maximum frequency occurred in the spring of 2009. Dust transported to Central Asia comes from regional sources, for example, Taklimakan desert and Aral Sea basin, and from long-range transport, for example, deserts of Arabia, Northeast Africa, Iran, and Pakistan. Regionalmore » sources are characterized by pollution transport with maximum values of coarse particles within the planetary boundary layer, aerosol optical thickness, extinction coefficient, integral coefficient of aerosol backscatter, and minimum values of the Ångström exponent. Pollution associated with air masses transported over long distances has different characteristics during autumn, winter, and spring. During winter, dust emissions were low resulting in high values of the Ångström exponent (about 0.51) and the fine particle mass fraction (64%). Dust storms were more frequent during spring with an increase in coarse dust particles in comparison to winter. The aerosol vertical profiles can be used to lower uncertainty in estimating radiative forcing.« less

  19. Project Overview: Cumulus Humilis Aerosol Processing Study (CHAPS): Proposed Summer 2007 ASP Field Campaign

    SciTech Connect

    Berkowitz, Carl M.; Berg, Larry K.; Ogren, J. A.; Hostetler, Chris A.; Ferrare, Richard

    2006-05-18

    This white paper presents the scientific motivation and preliminary logistical plans for a proposed ASP field campaign to be carried out in the summer of 2007. The primary objective of this campaign is to use the DOE Gulfstream-1 aircraft to make measurements characterizing the chemical, physical and optical properties of aerosols below, within and above large fields of fair weather cumulus and to use the NASA Langley Research Center’s High Spectral Resolution Lidar (HSRL) to make independent measurements of aerosol backscatter and extinction profiles in the vicinity of these fields. Separate from the science questions to be addressed by these observations will be information to add in the development of a parameterized cumulus scheme capable of including multiple cloud fields within a regional or global scale model. We will also be able to compare and contrast the cloud and aerosol properties within and outside the Oklahoma City plume to study aerosol processes within individual clouds. Preliminary discussions with the Cloud and Land Surface Interaction Campaign (CLASIC) science team have identified overlap between the science questions posed for the CLASIC Intensive Operation Period (IOP) and the proposed ASP campaign, suggesting collaboration would benefit both teams.

  20. Visible and near IR lidar backscatter observations on the GLOBE Pacific Survey missions

    NASA Technical Reports Server (NTRS)

    Spinhirne, James D.; Chudamani, S.; Cavanaugh, John F.

    1991-01-01

    Measurement techniques and initial results of the Global Backscatter Experiment (GLOBE) performed in November 1989 and May-June 1990 to provide data on prevailing values of atmospheric backscatter cross section are presented. The upper troposphere aerosol scattering cross section was low in the Southern Hemisphere for the May-June flights and low in the Northern Hemisphere for the November flights. The initial results indicate that the instrumentation and calibration techniques applied for the near IR lidar measurements were successful.

  1. Study of aerosol optical properties at Kunming in southwest China and long-range transport of biomass burning aerosols from North Burma

    NASA Astrophysics Data System (ADS)

    Zhu, J.; Xia, X.; Che, H.; Wang, J.; Zhang, J.; Duan, Y.

    2016-03-01

    Seasonal variation of aerosol optical properties and dominant aerosol types at Kunming (KM), an urban site in southwest China, is characterized. Substantial influences of the hygroscopic growth and long-range transport of biomass burning (BB) aerosols on aerosol optical properties at KM are revealed. These results are derived from a detailed analysis of (a) aerosol optical properties (e.g. aerosol optical depth (AOD), columnar water vapor (CWV), single scattering albedo (SSA) and size distribution) retrieved from sunphotometer measurements during March 2012-August 2013, (b) satellite AOD and active fire products, (c) the attenuated backscatter profiles from the space-born lidar, and (d) the back-trajectories. The mean AOD440nm and extinction Angstrom exponent (EAE440 - 870) at KM are 0.42 ± 0.32 and 1.25 ± 0.35, respectively. Seasonally, high AOD440nm (0.51 ± 0.34), low EAE440 - 870 (1.06 ± 0.34) and high CWV (4.25 ± 0.97 cm) during the wet season (May - October) contrast with their counterparts 0.17 ± 0.11, 1.40 ± 0.31 and 1.91 ± 0.37 cm during the major dry season (November-February) and 0.53 ± 0.29, 1.39 ± 0.19, and 2.66 ± 0.44 cm in the late dry season (March-April). These contrasts between wet and major dry season, together with the finding that the fine mode radius increases significantly with AOD during the wet season, suggest the importance of the aerosol hygroscopic growth in regulating the seasonal variation of aerosol properties. BB and Urban/Industrial (UI) aerosols are two major aerosol types. Back trajectory analysis shows that airflows on clean days during the major dry season are often from west of KM where the AOD is low. In contrast, air masses on polluted days are from west (in late dry season) and east (in wet season) of KM where the AOD is often large. BB air mass is found mostly originated from North Burma where BB aerosols are lifted upward to 5 km and then subsequently transported to southwest China via prevailing westerly winds.

  2. Aerosol optical properties measurement by recently developed cavity-enhanced aerosol single scattering albedometer

    NASA Astrophysics Data System (ADS)

    Zhao, Weixiong; Xu, Xuezhe; Zhang, Qilei; Fang, Bo; Qian, Xiaodong; Chen, Weidong; Gao, Xiaoming; Zhang, Weijun

    2015-04-01

    Development of appropriate and well-adapted measurement technologies for real-time in-situ measurement of aerosol optical properties is an important step towards a more accurate and quantitative understanding of aerosol impacts on climate and the environment. Aerosol single scattering albedo (SSA, ω), the ratio between the scattering (αscat) and extinction (αext) coefficients, is an important optical parameter that governs the relative strength of the aerosol scattering and absorption capacity. Since the aerosol extinction coefficient is the sum of the absorption and scattering coefficients, a commonly used method for the determination of SSA is to separately measure two of the three optical parameters - absorption, scattering and extinction coefficients - with different instruments. However, as this method involves still different instruments for separate measurements of extinction and absorption coefficients under different sampling conditions, it might cause potential errors in the determination of SSA value, because aerosol optical properties are very sensitive to the sampling conditions such as temperature and relative humidity (RH). In this paper, we report on the development of a cavity-enhanced aerosol single scattering albedometer incorporating incoherent broad-band cavity-enhanced spectroscopy (IBBCEAS) and an integrating sphere (IS) for direct in-situ measurement of aerosol scattering and extinction coefficients on the exact same sample volume. The cavity-enhanced albedometer holds great promise for high-sensitivity and high-precision measurement of ambient aerosol scattering and extinction coefficients (hence absorption coefficient and SSA determination) and for absorbing trace gas concentration. In addition, simultaneous measurements of aerosol scattering and extinction coefficients enable a potential application for the retrieval of particle number size distribution and for faster retrieval of aerosols' complex RI. The albedometer was deployed to

  3. Requirements For Lidar Aerosol and Ozone Measurements

    NASA Astrophysics Data System (ADS)

    Frey, S.; Woeste, L.

    Laser remote sensing is the preferable method, when spatial-temporal resolved data is required. Data from stationary laser remote sensing devices at the earth surface give a very good impression about daily, annual and in general time trends of a measurand and can be compared sometimes to airborne instruments to get a direct link between optical and other methods. Space borne measurements on the other hand are the only possibility for obtaining as much data, as modeller wish to have to initialise, compare or validate there computation. But in this case it is very difficult to get the input in- formation, which is necessary for good quantitative analysis as well as to find points for comparison. In outer space and other harsh field environments only the simplest and most robust equipment for the respective purpose should be applied, to ensure a long-term stable operation. The first question is: what do we have to know about the properties of the atmosphere to get reliable data from instruments, which are just simple enough?, and secondly: how to set-up the instruments? Even for the evaluation of backscatter coefficients a density profile and the so-called Lidar-ratio, the ratio of backscatter to total volume scatter intensity, is necessary. Raman Lidar is a possibility to handle this problem by measuring aerosol extinction profiles. But again a density profile and in addition a guess about the wavelength dependence of the aerosol extinc- tion between the Raman and laser wavelength are required. Unfortunately the tech- nique for Raman measurements is much more sensible and less suited for space borne measurements, because of the much smaller back scatter cross sections and the result- ing weak signals. It becomes worth, when we will have to maintain special laser with colours at molecular absorption bands in outer space, to measure gas concentration. I want to present simulation of optical systems for laser remote sensing, experimental experiences and compare air

  4. Effect of CALIPSO Cloud Aerosol Discrimination (CAD) Confidence Levels on Observations of Aerosol Properties near Clouds

    NASA Technical Reports Server (NTRS)

    Yang, Weidong; Marshak, Alexander; Varnai, Tamas; Liu, Zhaoyan

    2012-01-01

    CALIPSO aerosol backscatter enhancement in the transition zone between clouds and clear sky areas is revisited with particular attention to effects of data selection based on the confidence level of cloud-aerosol discrimination (CAD). The results show that backscatter behavior in the transition zone strongly depends on the CAD confidence level. Higher confidence level data has a flatter backscatter far away from clouds and a much sharper increase near clouds (within 4 km), thus a smaller transition zone. For high confidence level data it is shown that the overall backscatter enhancement is more pronounced for small clear-air segments and horizontally larger clouds. The results suggest that data selection based on CAD reduces the possible effects of cloud contamination when studying aerosol properties in the vicinity of clouds.

  5. Interstellar Extinction

    NASA Astrophysics Data System (ADS)

    Gontcharov, G. A.

    2016-12-01

    This review describes our current understanding of interstellar extinction. This differ substantially from the ideas of the 20th century. With infrared surveys of hundreds of millions of stars over the entire sky, such as 2MASS, SPITZER-IRAC, and WISE, we have looked at the densest and most rarefied regions of the interstellar medium at distances of a few kpc from the Sun. Observations at infrared and microwave wavelengths, where the bulk of the interstellar dust absorbs and radiates, have brought us closer to an understanding of the distribution of the dust particles on scales of the Galaxy and the universe. We are in the midst of a scientific revolution in our understanding of the interstellar medium and dust. Progress in, and the key results of, this revolution are still difficult to predict. Nevertheless, (a) a physically justified model has been developed for the spatial distribution of absorbing material over the nearest few kiloparsecs, including the Gould belt as a dust container, which gives an accurate estimate of the extinction for any object just by its galactic coordinates. It is also clear that (b) the interstellar medium contains roughly half the mass of matter in the galactic vicinity of the solar system (the other half is made up of stars, their remnants, and dark matter) and (c) the interstellar medium and, especially, dust, differ substantially in different regions of space and deep space cannot be understood by only studying near space.

  6. Impossible Extinction

    NASA Astrophysics Data System (ADS)

    Cockell, Charles S.

    2003-03-01

    Every 225 million years the Earth, and all the life on it, completes one revolution around the Milky Way Galaxy. During this remarkable journey, life is influenced by calamitous changes. Comets and asteroids strike the surface of the Earth, stars explode, enormous volcanoes erupt, and, more recently, humans litter the planet with waste. Many animals and plants become extinct during the voyage, but humble microbes, simple creatures made of a single cell, survive this journey. This book takes a tour of the microbial world, from the coldest and deepest places on Earth to the hottest and highest, and witnesses some of the most catastrophic events that life can face. Impossible Extinction tells this remarkable story to the general reader by explaining how microbes have survived on Earth for over three billion years. Charles Cockell received his doctorate from the University of Oxford, and is currently a microbiologist with rhe Search for Extraterrestrial Intelligence Institute (SETI), based at the British Antarctic Survey in Cambridge, UK. His research focusses on astrobiology, life in the extremes and the human exploration of Mars. Cockell has been on expeditions to the Arctic, Antarctic, Mongolia, and in 1993 he piloted a modified insect-collecting ultra-light aircraft over the Indonesian rainforests. He is Chair of the Twenty-one Eleven Foundation for Exploration, a charity that supports expeditions that forge links between space exploration and environmentalism.

  7. Backscattering of agglomerate particles

    NASA Astrophysics Data System (ADS)

    Zubko, Evgenij; Ovcharenko, Andrey; Bondarenko, Sergey; Shkuratov, Yuriy; Scotto, Cathy S.; Merritt, Charles; Hart, Matthew B.; Eversole, Jay D.; Videen, Gorden W.

    2004-12-01

    We examine how aggregation affects the light-scattering signatures, especially the polarization in the near-backward-scattering direction. We use the discrete dipole approximation (DDA) to study the backscatter of agglomerate particles consisting of oblong monomers. We examine the effects of monomer number and packing structure on the resulting negative polarization branch at small phase angle. We find large a dependence on the orientation of the monomers within the agglomerate and a smaller dependence on the number of monomers, suggesting that the mechanism producing the negative polarization minimum depends strongly on the interactions between the individual monomers. We also examine experimental measurements of substrates composed of biological cells. We find that the light-scattering signatures in the backward direction are not only different for different spore species, but for spores that have been prepared using different methodologies. These signatures are reproducible in different substrates composed of the spores from the same batches.

  8. Aerosol optical properties and mixing state of black carbon in the Pearl River Delta, China

    NASA Astrophysics Data System (ADS)

    Tan, Haobo; Liu, Li; Fan, Shaojia; Li, Fei; Yin, Yan; Cai, Mingfu; Chan, P. W.

    2016-04-01

    Aerosols contribute the largest uncertainty to the total radiative forcing estimate, and black carbon (BC) that absorbs solar radiation plays an important role in the Earth's energy budget. This study analysed the aerosol optical properties from 22 February to 18 March 2014 at the China Meteorological Administration Atmospheric Watch Network (CAWNET) station in the Pearl River Delta (PRD), China. The representative values of dry-state particle scattering coefficient (σsp), hemispheric backscattering coefficient (σhbsp), absorption coefficient (σabsp), extinction coefficient (σep), hemispheric backscattering fraction (HBF), single scattering albedo (SSA), as well as scattering Ångström exponent (α) were presented. A comparison between a polluted day and a clean day shows that the aerosol optical properties depend on particle number size distribution, weather conditions and evolution of the mixing layer. To investigate the mixing state of BC at the surface, an optical closure study of HBF between measurements and calculations based on a modified Mie model was employed for dry particles. The result shows that the mixing state of BC might be between the external mixture and the core-shell mixture. The average retrieved ratio of the externally mixed BC to the total BC mass concentration (rext-BC) was 0.58 ± 0.12, and the diurnal pattern of rext-BC can be found. Furthermore, considering that non-light-absorbing particles measured by a Volatility-Tandem Differential Mobility Analyser (V-TDMA) exist independently with core-shell and homogenously internally mixed BC particles, the calculated optical properties were just slightly different from those based on the assumption that BC exist in each particle. This would help understand the influence of the BC mixing state on aerosol optical properties and radiation budget in the PRD.

  9. Aerosol Optical Thickness comparisons between NASA LaRC Airborne HSRL and AERONET during the DISCOVER-AQ field campaigns

    NASA Astrophysics Data System (ADS)

    Scarino, A. J.; Ferrare, R. A.; Burton, S. P.; Hostetler, C. A.; Hair, J. W.; Rogers, R. R.; Berkoff, T.; Cook, A. L.; Harper, D. B.; Hoff, R. M.; Holben, B. N.; Schafer, J.; McGill, M. J.; Yorks, J. E.; Lantz, K. O.; Michalsky, J. J.; Hodges, G.

    2013-12-01

    The first- and second-generation NASA airborne High Spectral Resolution Lidars (HSRL-1 and HSRL-2) have been deployed on board the NASA Langley Research Center King Air aircraft during the Deriving Information on Surface Conditions from Column and VERtically Resolved Observations Relevant to Air Quality (DISCOVER-AQ) field campaigns. These included deployments during July 2011 over Washington, D.C. and Baltimore, MD and during January and February 2013 over the San Joaquin Valley (SJV) of California and also a scheduled deployment during September 2013 over Houston, TX. Measurements of aerosol extinction, backscatter, and depolarization are available from both HSRL-1 and HSRL-2 in coordination with other participating research aircraft and ground sites. These measurements constitute a diverse data set for use in characterizing the spatial and temporal distribution of aerosols, aerosol optical thickness (AOT), as well as the Mixing Layer Height (MLH). HSRL AOT is compared to AOT measured by the Distributed Regional Aerosol Gridded Observation Networks (DRAGON) and long-term AERONET sites. For the 2011 campaign, comparisons of AOT at 532nm between HSRL-1 and AERONET showed excellent agreement (r = 0.98, slope = 1.01, intercept = 0.037) when the King Air flights were within 2.5 km of the ground site and 10 min from the retrieval time. The comparison results are similar for the 2013 DISCOVER-AQ campaign in the SJV. Additional ground-based (MPL) and airborne (CPL) lidar data were used to help screen for clouds in the AERONET observations during the SJV portion. AOT values from a Multi-Filter Rotating Shadowband Radiometer (MFRSR) located at the Porterville, CA site during the SJV campaign are also compared to HSRL-2 AOT. Lastly, using the MLH retrieved from HSRL aerosol backscatter profiles, we describe the distribution of AOT relative to the MLH.

  10. Mediterranean aerosol typing by integrating three-wavelength lidar and sun photometer measurements.

    PubMed

    Perrone, M R; Burlizzi, P

    2016-07-01

    Backscatter lidar measurements at 355, 532, and 1064 nm combined with aerosol optical thicknesses (AOTs) from sun photometer measurements collocated in space and time were used to retrieve the vertical profiles of intensive and extensive aerosol parameters. Then, the vertical profiles of the Ångström coefficients for different wavelength pairs (Å(λ1, λ2, z)), the color ratio (CR(z)), the fine mode fraction (η(z)) at 532 nm, and the fine modal radius (R f (z)), which represent aerosol characteristic properties independent from the aerosol load, were used for typing the aerosol over the Central Mediterranean. The ability of the Ångström coefficients to identify the main aerosol types affecting the Central Mediterranean with the support of the backward trajectory analysis was first demonstrated. Three main aerosol types, which were designed as continental-polluted (CP), marine-polluted (MP), and desert-polluted (DP), were identified. We found that both the variability range and the vertical profile structure of the tested aerosol intensive parameters varied with the aerosol type. The variability range and the altitude dependence of the aerosol extinction coefficients at 355, 532, and 1064 nm, respectively, also varied with the identified aerosol types even if they are extensive aerosol parameters. DP, MP, and CP aerosols were characterized by the Å(532, 1064 nm) mean values ± 1 standard deviation equal to 0.5 ± 0.2, 1.1 ± 0.2, 1.6 ± 0.2, respectively. η(%) mean values ± 1SD were equal to 50 ± 10, 73 ± 7, and 86 ± 6 for DP, MP, and CP aerosols, respectively. The R f and CR mean values ± 1SD were equal to 0.16 ± 0.05 μm and 1.3 ± 0.3, respectively, for DP aerosols; to 0.12 ± 0.03 μm and 1.8 ± 0.4, respectively, for MP aerosols; and to 0.11 ± 0.02 μm and 1.7 ± 0.4, respectively, for CP aerosols. CP and DP aerosols were on average responsible for greater AOT and LR values, but

  11. Dust aerosol radiative effect and forcing over West Africa : A case study from the AMMA SOP

    NASA Astrophysics Data System (ADS)

    Lemaître, C.; Flamant, C.; Pelon, J.; Cuesta, J.; Chazette, P.; Raut, J. C.

    2009-04-01

    The massive transport of arid dust by the African easterly jet (AEJ) can impact the dynamic of the AEJ and modify the development of westerly African waves through modifications of horizontal temperature gradient. Hence, it is important to evaluate the radiative impact of dust and their effect on thermodynamical properties of the AEJ. In this presentation, the impact of aerosol on solar and infra-red fluxes and the heating rate due to dust over West Africa are investigated using the radiative code STREAMER, as well as space-borne and airborne lidars (CALIPSO and LEANDRE 2, respectively) as well as dropsonde observations acquired during the African Monsoon Multidisciplinary Analysis Special Observing Period. Aircraft operations were conducted on 13 and 14 June 2006, over Benin and Niger. On these days the dust observed over Benin and Niger originated from the Bodélé depression and from West Sudan. In this study, we use aerosol extinction coefficient derived from lidar, as well as temperature, pressure and water vapour profiles derived from dropsondes as inputs to STREAMER. The surface albedo is obtained with MODIS. A series of runs was carried out on 13 and 14 June 2006, around mid-day, to investigate the dust radiative forcing as a function of latitude, from 6°N to 15°N, i.e. between the vegetated coast of the Guinea Gulf and the arid Sahel. In the solar spectrum, the maximum heating rate associated with the dust plume on these days was comprised between 1.5 K/day and 3 K/day, depending on the aerosol load, over the entire Sudanian and Sahel regions as inferred from CALIPSO. Sensitivity studies to surface albedo, aerosol backscatter-to-extinction ratio, temperature and water vapor mixing ratio profiles were also conducted.

  12. 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)

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

    2008-07-01

    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

  13. Asian Aerosols: A Geophysical Fluid Dynamics Laboratory general circulation model sensitivity study of model response to aerosol optical depth and aerosol absorption

    NASA Astrophysics Data System (ADS)

    Randles, C. A.; Ramaswamy, V.

    2007-12-01

    Atmospheric absorption by black carbon (BC) aerosol heats the atmosphere while simultaneously cooling the surface and reducing latent and sensible heat fluxes from the land. Recent studies have shown that absorbing BC aerosol can have a large impact on regional climates, including modification of the hydrological cycle. However, significant uncertainties remain with regards to (a) the total amount of all aerosol species and (b) the amount of aerosol absorption. Here we present a GCM sensitivity study focusing on the influences due to total aerosol amount and aerosol absorption in the south and east Asian regions. Six experiments are conducted to test the equilibrium response of the GFDL AM2 GCM (under conditions of prescribed, observed sea surface temperatures) to (i) changes in aerosol absorption caused by changes in BC aerosol amount, and (ii) aerosol extinction optical depth increases corresponding to the year 1990 relative to a control case of 1950. In order to systematically explore the uncertainties in aerosol loading and absorption, the sensitivity experiments are classified into four regimes: low extinction optical depth, low absorption; low extinction optical depth, high absorption; high extinction optical depth, low absorption; and high extinction optical depth, high absorption. Changes in surface temperature and changes in the hydrological cycle are generally insignificant when lower aerosol extinction optical depths are considered. For higher extinction optical depths, the change in the modeled regional circulation relative to the control circulation over south and east Asia is affected by the amount of aerosol absorption and contrasts sharply to the regional circulation change associated with increasing only scattering aerosols. When increasing absorbing aerosols over the region, low-level convergence and increases in vertical velocity overcome the stabilizing effects of the absorbing aerosol and enhance the monsoonal circulation and precipitation rate

  14. A case study of dust aerosol radiative properties over Lanzhou, China

    NASA Astrophysics Data System (ADS)

    Zhang, L.; Cao, X.; Bao, J.; Zhou, B.; Huang, J.; Shi, J.; Bi, J.

    2010-02-01

    The vertical distribution of dust aerosol and its radiative properties are analysed using the data measured by the micropulse lidar, profiling microwave radiometer, sunphotometer, particulate monitor, and nephelometer at the Semi-Arid Climate and Environment Observatory of Lanzhou University (SACOL) during a dust storm from 27 March to 29 March 2007. The analysis shows that the dust aerosol mainly exists below 2 km in height, and the dust aerosol extinction coefficient decreases with height. The temporal evolution of aerosol optical depth (AOD) during the dust storm is characterized by a sub-maximum at 22:00 (Beijing Time) on 27 March and a maximum at 12:00 on 28 March. The AOD derived by lidar is compared with that obtained by sunphotometer, and shows a good consistency. The PM10 concentration and aerosol scattering coefficient share identical variation trends, and their maximums both appear at 22:00 on 27 March. The aerosol extinction coefficient and relative humidity have the same trends and their maximums appear at identical heights, showing a correlation between extinction coefficient and relative humidity known as aerosol hygroscopicity. Nevertheless, the correlation between aerosol extinction coefficient and temperature cannot be obviously seen. The aerosol extinction coefficient, scattering coefficient, and PM10 concentration present good linear correlations. The correlation coefficients of the aerosol scattering coefficient and PM10 concentration, of aerosol extinction coefficient and PM10 concentration, and of aerosol extinction and scattering coefficient are respectively 0.98, 0.94, and 0.96.

  15. Radiative Effects of Aerosols

    NASA Technical Reports Server (NTRS)

    Valero, Francisco P. J.

    1996-01-01

    During the Atlantic Stratocumulus Transition Experiment (ASTEX) in June 1992, two descents in cloud-free regions allowed comparison of the change in aerosol optical depth as determined by an onboard total-direct-diffuse radiometer (TDDR) to the change calculated from measured size-resolved aerosol microphysics and chemistry. Both profiles included a pollution haze from Europe but the second also included the effect of a Saharan dust layer above the haze. The separate contributions of supermicrometer (coarse) and submicrometer (fine) aerosol were determined and thermal analysis of the pollution haze indicated that the fine aerosol was composed primarily of a sulfate/water mixture with a refractory soot-like core. The soot core increased the calculated extinction by about 10% in the most polluted drier layer relative to a pure sulfate aerosol but had significantly less effect at higher humidities. A 3 km descent through a boundary layer air mass dominated by pollutant aerosol with relative humidities (RH) 10-77% yielded a close agreement between the measured and calculated aerosol optical depths (550 nm) of 0.160 (+/- 0.07) and 0. 157 (+/- 0.034) respectively. During descent the aerosol mass scattering coefficient per unit sulfate mass varied from about 5 to 16 m(exp 2)/g and primarily dependent upon ambient RH. However, the total scattering coefficient per total fine mass was far less variable at about 4+/- 0.7 m(exp 2)/g. A subsequent descent through a Saharan dust layer located above the pollution aerosol layer revealed that both layers contributed similarly to aerosol optical depth. The scattering per unit mass of the coarse aged dust was estimated at 1.1 +/- 0.2 m(exp 2)/g. The large difference (50%) in measured and calculated optical depth for the dust layer exceeded measurements.

  16. Retrieval of aerosol complex refractive index from a synergy between lidar, sunphotometer and in situ measurements during LISAIR experiment

    NASA Astrophysics Data System (ADS)

    Raut, J.-C.; Chazette, P.

    2007-06-01

    Particulate pollutant exchanges between the streets and the Planetary Boundary Layer (PBL), and their daily evolution linked to human activity were studied in the framework of the LIdar pour la Surveillance de l'AIR (LISAIR) experiment. This program lasted from 10 to 30 May 2005. A synergetic approach combining dedicated active (lidar) and passive (sunphotometer) remote sensors as well as ground based in situ instrumentation (nephelometer, aethalometer and particle sizers) was used to investigate urban aerosol optical properties within Paris. Aerosol complex refractive indices were assessed to be 1.56-0.034 i at 355 nm and 1.59-0.040 i at 532 nm, thus leading to single-scattering albedo values between 0.80 and 0.88. These retrievals are consistent with soot components in the aerosol arising from traffic exhausts indicating that these pollutants have a radiative impact on climate. We also discussed the influence of relative humidity on aerosol properties. A good agreement was found between vertical extinction profile derived from lidar backscattering signal and retrieved from the coupling between radiosounding and ground in situ measurements.

  17. Retrieval of aerosol complex refractive index from a synergy between lidar, sunphotometer and in situ measurements during LISAIR experiment

    NASA Astrophysics Data System (ADS)

    Raut, J.-C.; Chazette, P.

    2007-01-01

    Particulate pollutant exchanges between the streets and the Planetary Boundary Layer (PBL), and their daily evolution linked to human activity were studied in the framework of the LIdar pour la Surveillance de l'AIR (LISAIR) experiment. This program lasted from 10 to 30 May 2005. A synergetic approach combining dedicated active (lidar) and passive (sunphotometer) remote sensors as well as ground based in situ instrumentation (nephelometer, aethalometer and particle sizers) was used to investigate urban aerosol optical properties within Paris. Aerosol complex refractive indices were assessed to be 1.56-0.034i at 355 nm and 1.59-0.040i at 532 nm, thus leading to single-scattering albedo values between 0.80 and 0.88. These retrievals are consistent with soot components in the aerosol arising from traffic exhausts indicating that these pollutants have a radiative impact on climate. We also discussed the influence of relative humidity on aerosol properties. A good agreement was found between vertical extinction profile derived from lidar backscattering signal and retrieved from the coupling between radiosounding and ground in situ measurements.

  18. Inference of stratospheric aerosol composition and size distribution from SAGE II satellite measurements

    NASA Technical Reports Server (NTRS)

    Wang, Pi-Huan; Mccormick, M. P.; Fuller, W. H.; Yue, G. K.; Swissler, T. J.; Osborn, M. T.

    1989-01-01

    A method for inferring stratospheric aerosol composition and size distribution from the water vapor concentration and aerosol extinction measurements obtained in the Stratospheric Aerosol and Gas Experiment (SAGE) II and the associated temperature from the NMC. The aerosols are assumed to be sulfuric acid-water droplets. A modified Levenberg-Marquardt algorithm is used to determine model size distribution parameters based on the SAGE II multiwavelength aerosol extinctions. It is found that the best aerosol size information is contained in the aerosol radius range between about 0.25 and 0.80 micron.

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

    NASA Astrophysics Data System (ADS)

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

    1997-05-01

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

    2006-05-01

    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.

  1. Mobile multi-wavelength polarization Raman lidar for water vapor, cloud and aerosol measurement.

    PubMed

    Wu, Songhua; Song, Xiaoquan; Liu, Bingyi; Dai, Guangyao; Liu, Jintao; Zhang, Kailin; Qin, Shengguang; Hua, Dengxin; Gao, Fei; Liu, Liping

    2015-12-28

    Aiming at the detection of atmospheric water vapor mixing ratio, depolarization ratio, backscatter coefficient, extinction coefficient and cloud information, the Water vapor, Cloud and Aerosol Lidar (WACAL) is developed by the lidar group at Ocean University of China. The lidar consists of transmitter, receiver, data acquisition and auxiliary system. For the measurement of various atmospheric physical properties, three channels including Raman channel, polarization channel and infrared channel are integrated in WACAL. The integration and working principle of these channels are introduced in details. The optical setup, the housekeeping of the system and the data retrieval routines are also presented. After the completion of the construction of the lidar, the WACAL system was installed in Ocean University of China (36.165°N, 120.5°E), Qingdao for the measurement of atmosphere during 2013 and 2014. The measurement principles and some case studies corresponding to various atmospheric physical properties are provided. Finally, the result of one continuous measurement example operated on 13 June 2014 is presented. The WACAL can measure the aerosol and cloud optical properties as well as the water vapor mixing ratio. It is useful for studying the direct and indirect effects of the aerosol on the climate change.

  2. Airborne backscatter lidar measurements at three wavelengths during ELITE

    NASA Astrophysics Data System (ADS)

    Schreiber, H. G.; Wirth, Martin; Moerl, P.; Renger, Wolfgang

    1995-09-01

    The German Aerospace Establishment (DLR) operates an airborne backscatter lidar based on a Nh:YAG laser which is flashlamp-pumped at 10 Hz. It works on the wavelengths 1064, 532, and 354 nm. It is mounted downward-looking on the research aircraft Falcon 20, flying at about 12 km altitude at speeds of 200 m/s. We present airborne measurements correlated with the orbit tracks of the shuttle-borne LITE-instrument (lidar in-space technology experiment). The emphasis in data evalution is on the comparison between the airborne and the shuttle- borne lidars. First results show excellent agreement between the two instruments even on details of cirrus clouds. The results comprise cloud geometrical and optical depths, as well as profiles of aerosol backscattering coefficients at three wavelengths.

  3. Airborne Aerosol Closure Studies During PRIDE

    NASA Technical Reports Server (NTRS)

    Redemann, Jens; Livingston, John M.; Russell, Philip B.; Schmid, Beat; Reid, Jeff

    2000-01-01

    The Puerto Rico Dust Experiment (PRIDE) was conducted during June/July of 2000 to study the properties of Saharan dust aerosols transported across the Atlantic Ocean to the Caribbean Islands. During PRIDE, the NASA Ames Research Center six-channel (380 - 1020 nm) airborne autotracking sunphotometer (AATS-6) was operated aboard a Piper Navajo airplane alongside a suite of in situ aerosol instruments. The in situ aerosol instrumentation relevant to this paper included a Forward Scattering Spectrometer Probe (FSSP-100) and a Passive Cavity Aerosol Spectrometer Probe (PCASP), covering the radius range of approx. 0.05 to 10 microns. The simultaneous and collocated measurement of multi-spectral aerosol optical depth and in situ particle size distribution data permits a variety of closure studies. For example, vertical profiles of aerosol optical depth obtained during local aircraft ascents and descents can be differentiated with respect to altitude and compared to extinction profiles calculated using the in situ particle size distribution data (and reasonable estimates of the aerosol index of refraction). Additionally, aerosol extinction (optical depth) spectra can be inverted to retrieve estimates of the particle size distributions, which can be compared directly to the in situ size distributions. In this paper we will report on such closure studies using data from a select number of vertical profiles at Cabras Island, Puerto Rico, including measurements in distinct Saharan Dust Layers. Preliminary results show good agreement to within 30% between mid-visible aerosol extinction derived from the AATS-6 optical depth profiles and extinction profiles forward calculated using 60s-average in situ particle size distributions and standard Saharan dust aerosol refractive indices published in the literature. In agreement with tendencies observed in previous studies, our initial results show an underestimate of aerosol extinction calculated based on the in situ size distributions

  4. Infrared spectroscopy of aerosols

    NASA Astrophysics Data System (ADS)

    Mentel, Th.; Sebald, H.

    2003-04-01

    In our large Aerosol Chamber at the FZ Jülich we apply HR FTIR absorption spectroscopy for the determination of trace gases. In the FTIR spectra we also observe broad absorptions of several 10 to a few 100 cm-1 widths that arise from species in the condensed aerosol phase: liquid H_2O, NO_3^-, SO_42-, HSO_4^-, or dicarboxylic acids. Moreover, the aerosol droplets caused extinctions over several 1000 cm-1 by IR scattering. This allows for in-situ observation of changes in the condensed aerosol phase e.g. on HNO_3 uptake, like the shift of the sulfate/bisulfate equilibrium or the growth by water condensation. The IR absorptions of the condensed aerosol phase provide useful extra information in process studies, if they can be quantified. Therefore the absorption cross section, respective, the absorption index which is the imaginary part of the complex refractive index is needed. We set up an aerosol flow tube in which IR spectroscopy on a 8 m light path and aerosol size distribution measurements in the range from 20 nm - 10 μm can be performed simultaneously. We measured sulfate aerosols at several relative humidities (dry, metastable, deliquescent). We will demonstrate an iterative procedure based on Mie calculations and Kramers Kronig transformation to retrieve the absorption index from the observed IR spectra and the corresponding size distribution (for dry ammonium sulfate). We will compare resulting absorption indices for aqueous sodium bisulfate aerosols at several relative humidties with thermodynamic model calculations for the Na^+/H^+/HSO_4^-/SO_42-/H_2O system.

  5. 3D Backscatter Imaging System

    NASA Technical Reports Server (NTRS)

    Turner, D. Clark (Inventor); Whitaker, Ross (Inventor)

    2016-01-01

    Systems and methods for imaging an object using backscattered radiation are described. The imaging system comprises both a radiation source for irradiating an object that is rotationally movable about the object, and a detector for detecting backscattered radiation from the object that can be disposed on substantially the same side of the object as the source and which can be rotationally movable about the object. The detector can be separated into multiple detector segments with each segment having a single line of sight projection through the object and so detects radiation along that line of sight. Thus, each detector segment can isolate the desired component of the backscattered radiation. By moving independently of each other about the object, the source and detector can collect multiple images of the object at different angles of rotation and generate a three dimensional reconstruction of the object. Other embodiments are described.

  6. Aerosol in the Pacific troposphere

    NASA Technical Reports Server (NTRS)

    Clarke, Antony D.

    1989-01-01

    The use of near real-time optical techniques is emphasized for the measurement of mid-tropospheric aerosol over the Central Pacific. The primary focus is on measurement of the aerosol size distribution over the range of particle diameters from 0.15 to 5.0 microns that are essential for modeling CO2 backscatter values in support of the laser atmospheric wind sounder (LAWS) program. The measurement system employs a LAS-X (Laser Aerosol Spectrometer-PMS, Boulder, CO) with a custom 256 channel pulse height analyzer and software for detailed measurement and analysis of aerosol size distributions. A thermal preheater system (Thermo Optic Aerosol Descriminator (TOAD) conditions the aerosol in a manner that allows the discrimination of the size distribution of individual aerosol components such as sulfuric acid, sulfates and refractory species. This allows assessment of the relative contribution of each component to the BCO2 signal. This is necessary since the different components have different sources, exhibit independent variability and provide different BCO2 signals for a given mass and particle size. Field activities involve experiments designed to examine both temporal and spatial variability of these aerosol components from ground based and aircraft platforms.

  7. Quality Screening Algorithms Implemented in the New CALIPSO Level 3 Aerosol Profile Product

    NASA Astrophysics Data System (ADS)

    Tackett, J. L.; Winker, D. M.; Getzewich, B. J.; Vaughan, M.

    2012-12-01

    Global observations of aerosol extinction profiles can improve the ability of climate models to properly account for aerosol radiative forcing in Earth's atmosphere. In response to this need, a new CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) level 3 aerosol profile product has been released which for the first time provides monthly, globally gridded and quality-screened aerosol extinction profiles within the troposphere for the entire 6-year mission. Level 3 aerosol extinction profiles are aggregated from CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) lidar extinction retrievals reported in the CALIPSO level 2 aerosol profile product onto an equal-angle grid after quality screening algorithms are applied to reduce occurrences of failed retrievals, misclassified aerosol, surface contamination, and spurious outliers. Implementation of these quality screening algorithms is a substantial value to aerosol modeling groups who desire high confidence datasets without having to independently develop quality screening metrics. Furthermore, quality screening is paramount to understand the scientific content of the resultant CALIPSO level 3 aerosol profile product since classification and retrieval errors in level 2 aerosol data may lead to misinterpretation of the distribution and optical properties of aerosol in the troposphere. This presentation summarizes the averaging and quality screening algorithms implemented in the CALIPSO level 3 aerosol profile product, provides rationale for their implementation, and discusses averaging and filtering differences unique to CALIPSO data compared to level 3 products aggregated from passive satellite measurements. Examples are given that illustrate the benefits of quality screening and the dangers of improper screening CALIPSO level 2 aerosol extinction data. Sensitivity study results are presented to highlight the impact of quality screening on final level 3 statistics. Since overlying cloud

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

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

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

  9. Photoelectron backscattering in vacuum phototubes

    NASA Astrophysics Data System (ADS)

    Lubsandorzhiev, B. K.; Vasiliev, R. V.; Vyatchin, Y. E.; Shaibonov, B. A. J.

    2006-11-01

    In this article we describe results of studies of a photoelectron backscattering effect in vacuum phototubes: classical photomultipliers (PMT) and hybrid phototubes (PH). Late pulses occurring in PMTs are attributed to the photoelectron backscattering and distinguished from pulses due to an anode glow effect. The late pulses are measured in a number of PMTs and HPs with various photocathode sizes covering 1 50 cm range and different types of the first dynode materials and construction designs. It is shown that the late pulses are a generic feature of all vacuum photodetectors—PMTs and PHs—and they do not deteriorate dramatically amplitude and timing responses of vacuum phototubes.

  10. A new description of Titan's aerosol optical properties from the analysis of VIMS Emission Phase Function observations

    NASA Astrophysics Data System (ADS)

    Rodriguez, Sebastien; Maltagliati, Luca; Sotin, Christophe; Rannou, Pascal; Bézard, Bruno; Cornet, Thomas

    2016-10-01

    The Huygens probe gave unprecedented information on the properties of Titan's aerosols (vertical distribution, opacity as a function of wavelength, phase function, single scattering albedo) by in-situ measurements (Tomasko et al. 2008). Being the only existing in-situ atmospheric probing for Titan, this aerosol model currently is the reference for many Titan studies (e.g. by being applied as physical input in radiative transfer models of the atmosphere). Recently a reanalysis of the DISR dataset, corroborated by data from the Downward-Looking Visible Spectrometer (DLVS), was carried out by the same group (Doose et al. 2016), leading to significant changes to the indications given by Tomasko et al. (2008).Here we present the analysis of the Emission Phase Function observation (EPF) performed by VIMS during the Cassini flyby T88 (November 2012). An EPF observes the same spot on the surface (and thus the same atmosphere) with the same emergence angle but with different incidence angles. In this way, our EPF allows, for the first time, to have direct information on the phase function of Titan's aerosols, as well as on other important physical parameters of the aerosols as the behavior of their extinction as a function of wavelength and the single scattering albedo (also as a function of wavelength) for the whole VIMS range (0.8-5.2 μm). The T88 EPF is composed of 25 VIMS datacubes spanning a scattering angle range approximately from 0°to 70°.We used the radiative transfer model described in Hirtzig et al. (2013) as baseline, updated with improved methane (+ related isotopes) spectroscopy. By changing the aerosol description in the model, we found the combination of aerosol optical parameters that fits best a constant aerosol column density over the whole set of the VIMS datacubes. We confirmed that the new results from Doose et al. (2016) do improve the fit for what concerns the vertical profile and the extinction as a function of wavelength. However, a different

  11. A new description of Titan's aerosol optical properties from the analysis of VIMS Emission Phase Function observations

    NASA Astrophysics Data System (ADS)

    Maltagliati, Luca; Rodriguez, Sebastien; Sotin, Christophe; Rannou, Pascal; Bezard, Bruno; Cornet, Thomas

    2016-06-01

    The Huygens probe gave unprecedented information on the properties of Titan's aerosols (vertical distribution, opacity as a function of wavelength, phase function, single scattering albedo) by in-situ measurements (Tomasko et al. 2008). Being the only existing in-situ atmospheric probing for Titan, this aerosol model currently is the reference for many Titan studies (e.g. by being applied as physical input in radiative transfer models of the atmosphere). Recently a reanalysis of the DISR dataset, corroborated by data from the Downward-Looking Visible Spectrometer (DLVS), was carried out by the same group (Doose et al. 2016), leading to significant changes to the indications given by Tomasko et al. (2008). Here we present the analysis of the Emission Phase Function observation (EPF) performed by VIMS during the Cassini flyby T88 (November 2012). An EPF observes the same spot on the surface (and thus the same atmosphere) with the same emergence angle but with different incidence angles. In this way, our EPF allows, for the first time, to have direct information on the phase function of Titan's aerosols, as well as on other important physical parameters of the aerosols as the behavior of their extinction as a function of wavelength and the single scattering albedo (also as a function of wavelength) for the whole VIMS range (0.8-5.2 µm). The T88 EPF is composed of 25 VIMS datacubes spanning a scattering angle range approximately from 0°to 70°. We used the radiative transfer model described in Hirtzig et al. (2013) as baseline, updated with improved methane (+ related isotopes) spectroscopy. By changing the aerosol description in the model, we found the combination of aerosol optical parameters that fits best a constant aerosol column density over the whole set of the VIMS datacubes. We confirmed that the new results from Doose et al. (2016) do improve the fit for what concerns the vertical profile and the extinction as a function of wavelength. However, a different

  12. Cirrus cloud transmittance and backscatter in the infrared measured with a CO(2) lidar.

    PubMed

    Hall, F F; Cupp, R E; Troxel, S W

    1988-06-15

    Two independent methods of measuring the transmittance of cirrus clouds are compared. Both used a CO(2) pulsed Doppler lidar at a wavelength of 10.59 microm. The first method used backscatter from the calibration target El Chichon stratospheric cloud that was present over Boulder in 1982 and 1983. The second method used conical lidar scans at different zenith angles when uniform cirrus decks were present. Extinction coefficients measured from both methods average 0.1 km(-1) for tenuous cirrus 1.0 km thick to 0.78 km(-1) for cirrus several kilometers thick. There is a wide standard deviation in extinction values. Extinction-tobackscatter ratios S vary from <1000 sr for tenuous clouds to 2600 sr for dense clouds. Mie scattering and extinction calculations for spherical ice particles of 10-50 microm in radius lead to ratios S > 2000 sr, so long as the ice absorption is entered into the calculations. The backscattering ratio for ice cylinders is 1 order of magnitude lower than for spheres. Backscatter in the IR may, therefore, be reasonably well modeled by some combination of spheres and cylinders. Cloud thickness statistics from lidar returns show that cirrus decks average ~500 m thick. Clouds thinner than 300 m were often overlooked by the unaided surface-based observer. These preliminary results are in rather close agreement with the LOWTRAN 6 cirrus cloud model predictions.

  13. The nature of extinction.

    PubMed

    Delord, Julien

    2007-09-01

    The phenomenon of species extinction raises more and more concern among ecologists facing the actual crisis of biodiversity. Scientific investigations of the causes and effects of extinction must be completed by a philosophical analysis of the concept of extinction that aims to clarify the meanings of the term 'extinction' and to analyse modalities, criteria and degrees of extinction. We will focus our attention on the apparent paradox of the possible 'resurrection' of species in the near future with the help of genetic biotechnology and cloning techniques. The ontological background of the extinction concept is analysed in relation to the idea of species as classes. We will also show that there is no simple analogy between death and species extinction, and develop a conceptualist and dualistic system of supra-individual entities (species vs. population), supported by an instrumentalist approach to genetic manipulations which transform species into interactive kinds, which can go extinct and be recreated.

  14. Laser transmission-backscattering through inhomogeneous cirrus clouds.

    PubMed

    Ou, Szu-Cheng; Takano, Yoshihide; Liou, Kuo-Nan; Lefevre, Randy J; Johnson, Michael W

    2002-09-20

    We have developed a two-dimensional (2D) model for inhomogeneous cirrus clouds in plane-parallel and spherical geometries for the analysis of the transmission and backscattering of high-energy laser beams. The 2D extinction-coefficient and mean effective ice-crystal size fields for cirrus clouds can be determined from a combination of the remote sensing of cirrus clouds by use of the Advanced Very High Resolution Radiometer on board National Oceanic and Atmospheric Administration satellites and the vertical profiling of ice-crystal size distributions available from limited measurements. We demonstrate that satellite remote sensing of the position and the composition of high cirrus can be incorporated directly in the computer model developed for the transmission and backscattering of high-energy laser beams in realistic atmospheres. The results of laser direct transmission, forward scattering, and backscattering are analyzed carefully with respect to aircraft height, cirrus cloud optical depth, and ice-crystal size and orientation. Uncertainty in laser transmission that is due to errors in the retrieved ice-crystal size is negligible. But uncertainty of the order of 2% can be produced if the retrieved optical depth has errors of +/-0.05. With both the aircraft and the target near the cloud top, the direct transmission decreases, owing to the propagation of the laser beam through the curved portion of the cloud top. This effect becomes more pronounced as the horizontal distance between the aircraft and the target increases.

  15. Ground-based network observation using Mie-Raman lidars and multi-wavelength Raman lidars and algorithm to retrieve distributions of aerosol components

    NASA Astrophysics Data System (ADS)

    Nishizawa, Tomoaki; Sugimoto, Nobuo; Matsui, Ichiro; Shimizu, Atsushi; Hara, Yukari; Itsushi, Uno; Yasunaga, Kazuaki; Kudo, Rei; Kim, Sang-Woo

    2017-02-01

    We improved two-wavelength polarization Mie-scattering lidars at several main sites of the Asian dust and aerosol lidar observation network (AD-Net) by adding a nitrogen Raman scatter measurement channel at 607 nm and have conducted ground-based network observation with the improved Mie-Raman lidars (MRL) in East Asia since 2009. This MRL provides 1α+2β+1δ data at nighttime: extinction coefficient (α532), backscatter coefficient (β532), and depolarization ratio (δ532) of particles at 532 nm and an attenuated backscatter coefficient at 1064 nm (βat,1064). Furthermore, we developed a Multi-wavelength Mie-Raman lidar (MMRL) providing 2α+3β+2δ data (α at 355 and 532 nm; β at 355 and 532; βat at 1064 nm; and δ at 355 and 532 nm) and constructed MMRLs at several main sites of the AD-Net. We identified an aerosol-rich layer and height of the planetary boundary layer (PBL) using βat,1064 data, and derived aerosol optical properties (AOPs, for example, αa, βa, δa, and lidar ratio (Sa)). We demonstrated that AOPs cloud be derived with appropriate accuracy. Seasonal means of AOPs in the PBL were evaluated for each MRL observation site using three-year data from 2010 through 2012; the AOPs changed according to each season and region. For example, Sa,532 at Fukue, Japan, were 44±15 sr in winter and 49±17 in summer; those at Seoul, Korea, were 56±18 sr in winter and 62±15 sr in summer. We developed an algorithm to estimate extinction coefficients at 532 nm for black carbon, dust, sea-salt, and air-pollution aerosols consisting of a mixture of sulfate, nitrate, and organic-carbon substances using the 1α532+2β532 and 1064+1δ532 data. With this method, we assume an external mixture of aerosol components and prescribe their size distributions, refractive indexes, and particle shapes. We applied the algorithm to the observed data to demonstrate the performance of the algorithm and determined the vertical structure for each aerosol component.

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

    PubMed Central

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

    2013-01-01

    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

  17. Rayleigh-backscattering doppler broadening correction for differential absorption lidar

    NASA Astrophysics Data System (ADS)

    Fan, Lanlan; Zhang, Yinchao; Chen, Siying; Guo, Pan; Chen, He

    2015-11-01

    The spectral broadening by Rayleigh backscattering can cause large changes in water vapor echo signals, causing errors when the water vapor concentration is inversed by differential absorption lidar (DIAL). A correction algorithm is proposed to revise the errors due to the effect of laser spectral broadening. The relative errors of water vapor are calculated in cases of different aerosol distribution and temperature changes before and after correction. The results show that measurement errors due to the Doppler broadening are more than 5% before correction and a 2% measurement error after corrected for the case of a smooth, background aerosol distribution. However, due to the high aerosol gradients and strong temperature inversion, errors can be up to 40% and 10% with no corrections for this effect, respectively. The relative errors can reduce to less than 2% after correction. Hence, the correction algorithm for Rayleigh Doppler broadening can improve detection accuracy in H2O DIAL measurements especially when it is applied to high aerosol concentration or strong temperature inversion.

  18. Backscatter LIDAR signal simulation applied to spacecraft LIDAR instrument design

    NASA Astrophysics Data System (ADS)

    Fochesatto, J.; Ristori, P.; Flamant, P.; Machado, M. E.; Singh, U.; Quel, E.

    2004-01-01

    In the framework of the scientific cooperation between the CEILAP laboratory (Argentina) and IPSL Institut Pierre Simon Laplace (France), devoted to the development of LIDAR techniques for Atmospheric sciences, a new area of scientific research, involving LIDARs, is starting in Argentine space technology. This new research area is under consideration at CEILAP in a joint effort with CONAE, the Argentine space agency, responsible for the development of future space missions. The LIDAR technique is necessary to improve our knowledge of meteorological, dynamic, and radiative processes in the South American region, for the whole troposphere and the lower stratosphere. To study this future mission, a simple model for the prediction of backscatter LIDAR signal from a spacecraft platform has been used to determine dimensions and detection characteristics of the space borne LIDAR instrument. The backscatter signal was retrieved from a modeled atmosphere considering its molecular density profile and taking into account different aerosols and clouds conditions. Signal-to-noise consideration, within the interval of possible dimension of the instrument parameters, allows us to constrain the telescope receiving area and to derive maximum range achievable, integration time and the final spatial and temporal resolutions of backscatter profiles.

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

    NASA Astrophysics Data System (ADS)

    Wilkerson, Thomas D.; Bingham, Gail E.; Zavyalov, Vladimir V.; 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.

    2006-12-01

    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 interferometric filters permit all wavelengths to be measured simultaneously, day or night, using photon counting by MTs, an APD, and fast data acquisition. The lidar housing is a transportable trailer suitable for all-weather operation at any accessible site. We direct the laser and telescope FOVs to targets of interest in both azimuth and elevation. The lidar has been applied in atmospheric studies at a swine production farm in Iowa and a dairy in Utah. Prominent aerosol plumes emitted from the swine facility were measured as functions of temperature, turbulence, stability and the animal feed cycle. Particle samplers and turbulence detectors were used by colleagues specializing in those fields. Lidar measurements also focused on air motion as seen by scans of the farm volume. The value of multi-wavelength, eye-safe lidars for agricultural aerosol measurements has been confirmed by the successful operation of AGLITE.

  20. Is extinction forever?

    PubMed Central

    Bridge, Eli S.; Crawford, Priscilla H. C.; Hough, Daniel J.; Kelly, Jeffrey F.; Patten, Michael A.

    2015-01-01

    Mistrust of science has seeped into public perception of the most fundamental aspect of conservation—extinction. The term ought to be straightforward, and yet, there is a disconnect between scientific discussion and public views. This is not a mere semantic issue, rather one of communication. Within a population dynamics context, we say that a species went locally extinct, later to document its return. Conveying our findings matters, for when we use local extinction, an essentially nonsensical phrase, rather than extirpation, which is what is meant, then we contribute to, if not create outright, a problem for public understanding of conservation, particularly as local extinction is often shortened to extinction in media sources. The public that receives the message of our research void of context and modifiers comes away with the idea that extinction is not forever or, worse for conservation as a whole, that an extinction crisis has been invented. PMID:25711479

  1. Stratospheric aerosol forcing for climate modeling: 1850-1978

    NASA Astrophysics Data System (ADS)

    Arfeuille, Florian; Luo, Beiping; Thomason, Larry; Vernier, Jean-Paul; Peter, Thomas

    2016-04-01

    We present here a stratospheric aerosol dataset produced using the available aerosol optical depth observations from the pre-satellite period. The scarce atmospheric observations are supplemented by additional information from an aerosol microphysical model, initialized by ice-core derived sulfur emissions. The model is used to derive extinctions at all altitudes, latitudes and times when sulfur injections are known for specific volcanic eruptions. The simulated extinction coefficients are then scaled to match the observed optical depths. In order to produce the complete optical properties at all wavelengths (and the aerosol surface area and volume densities) needed by climate models, we assume a lognormal size distribution of the aerosols. Correlations between the extinctions in the visible and the effective radius and distribution width parameters are taken from the better constrained SAGE II period. The aerosol number densities are then fitted to match the derived extinctions in the 1850-1978 period. From these aerosol size distributions, we then calculate extinction coefficients, single scattering albedos and asymmetry factors at all wavelengths using the Mie theory. The aerosol surface area densities and volume densities are also provided.

  2. Backscatter measurements for NIF ignition targets (invited).

    PubMed

    Moody, J D; Datte, P; Krauter, K; Bond, E; Michel, P A; Glenzer, S H; Divol, L; Niemann, C; Suter, L; Meezan, N; MacGowan, B J; Hibbard, R; London, R; Kilkenny, J; Wallace, R; Kline, J L; Knittel, K; Frieders, G; Golick, B; Ross, G; Widmann, K; Jackson, J; Vernon, S; Clancy, T

    2010-10-01

    Backscattered light via laser-plasma instabilities has been measured in early NIF hohlraum experiments on two beam quads using a suite of detectors. A full aperture backscatter system and near backscatter imager (NBI) instrument separately measure the stimulated Brillouin and stimulated Raman scattered light. Both instruments work in conjunction to determine the total backscattered power to an accuracy of ∼15%. In order to achieve the power accuracy we have added time-resolution to the NBI for the first time. This capability provides a temporally resolved spatial image of the backscatter which can be viewed as a movie.

  3. Stratospheric Aerosol Measurements

    NASA Technical Reports Server (NTRS)

    Pueschel, Rudolf, F.; Gore, Warren J. (Technical Monitor)

    1998-01-01

    Stratospheric aerosols affect the atmospheric energy balance by scattering and absorbing solar and terrestrial radiation. They also can alter stratospheric chemical cycles by catalyzing heterogeneous reactions which markedly perturb odd nitrogen, chlorine and ozone levels. Aerosol measurements by satellites began in NASA in 1975 with the Stratospheric Aerosol Measurement (SAM) program, to be followed by the Stratospheric Aerosol and Gas Experiment (SAGE) starting in 1979. Both programs employ the solar occultation, or Earth limb extinction, techniques. Major results of these activities include the discovery of polar stratospheric clouds (PSCs) in both hemispheres in winter, illustrations of the impacts of major (El Chichon 1982 and Pinatubo 1991) eruptions, and detection of a negative global trend in lower stratospheric/upper tropospheric aerosol extinction. This latter result can be considered a triumph of successful worldwide sulfur emission controls. The SAGE record will be continued and improved by SAGE III, currently scheduled for multiple launches beginning in 2000 as part of the Earth Observing System (EOS). The satellite program has been supplemented by in situ measurements aboard the ER-2 (20 km ceiling) since 1974, and from the DC-8 (13 km ceiling) aircraft beginning in 1989. Collection by wire impactors and subsequent electron microscopic and X-ray energy-dispersive analyses, and optical particle spectrometry have been the principle techniques. Major findings are: (1) The stratospheric background aerosol consists of dilute sulfuric acid droplets of around 0.1 micrometer modal diameter at concentration of tens to hundreds of monograms per cubic meter; (2) Soot from aircraft amounts to a fraction of one percent of the background total aerosol; (3) Volcanic eruptions perturb the sulfuric acid, but not the soot, aerosol abundance by several orders of magnitude; (4) PSCs contain nitric acid at temperatures below 195K, supporting chemical hypotheses

  4. Backscatter absorption gas imaging system

    DOEpatents

    McRae, T.G. Jr.

    A video imaging system for detecting hazardous gas leaks. Visual displays of invisible gas clouds are produced by radiation augmentation of the field of view of an imaging device by radiation corresponding to an absorption line of the gas to be detected. The field of view of an imager is irradiated by a laser. The imager receives both backscattered laser light and background radiation. When a detectable gas is present, the backscattered laser light is highly attenuated, producing a region of contrast or shadow on the image. A flying spot imaging system is utilized to synchronously irradiate and scan the area to lower laser power requirements. The imager signal is processed to produce a video display.

  5. Backscatter absorption gas imaging system

    DOEpatents

    McRae, Jr., Thomas G.

    1985-01-01

    A video imaging system for detecting hazardous gas leaks. Visual displays of invisible gas clouds are produced by radiation augmentation of the field of view of an imaging device by radiation corresponding to an absorption line of the gas to be detected. The field of view of an imager is irradiated by a laser. The imager receives both backscattered laser light and background radiation. When a detectable gas is present, the backscattered laser light is highly attenuated, producing a region of contrast or shadow on the image. A flying spot imaging system is utilized to synchronously irradiate and scan the area to lower laser power requirements. The imager signal is processed to produce a video display.

  6. Electromagnetic backscattering by corner reflectors

    NASA Technical Reports Server (NTRS)

    Balanis, C. A.; Griesser, T.

    1986-01-01

    The Geometrical Theory of Diffraction (GTD), which supplements Geometric Optics (GO), and the Physical Theory of Diffraction (PTD), which supplements Physical Optics (PO), are used to predict the backscatter cross sections of dihedral corner reflectors which have right, obtuse, or acute included angles. These theories allow individual backscattering mechanisms of the dihedral corner reflectors to be identified and provide good agreement with experimental results in the azimuthal plane. The advantages and disadvantages of the geometrical and physical theories are discussed in terms of their accuracy, usefulness, and complexity. Numerous comparisons of analytical results with experimental data are presented. While physical optics alone is more accurate and more useful than geometrical optics alone, the combination of geometrical optics and geometrical diffraction seems to out perform physical optics and physical diffraction when compared with experimental data, especially for acute angle dihedral corner reflectors.

  7. Using the OMI Aerosol Index and Absorption Aerosol Optical Depth to Evaluate the NASA MERRA Aerosol Reanalysis.

    NASA Astrophysics Data System (ADS)

    Buchard, V.; da Silva, A. M., Jr.; Colarco, P. R.; Darmenov, A.; Govindaraju, R.

    2014-12-01

    A radiative transfer interface has been developed to simulate the UV Aerosol Index (AI) from the NASA Goddard Earth Observing System version 5 (GEOS-5) aerosol assimilated fields. The purpose of this work is to use the AI derived from the Ozone Monitoring Instrument (OMI) measurements as independent validation for the Modern Era Retrospective analysis for Research and Applications Aerosol Reanalysis (MERRAero). In this presentation we show comparisons of model produced AI with the corresponding OMI measurements during several months of 2007 characterized by a good sampling of dust and biomass burning events. In parallel, model produced Absorption Aerosol Optical Depth (AAOD) were compared to OMI AAOD for the same period, identifying regions where the model representation of absorbing aerosols were deficient. Since AI is dependent on aerosol concentration, optical properties and altitude of the aerosol layer, we make use of complementary observations to fully diagnose the model, including AOD from the Multi-angle Imaging SpectroRadiometer (MISR) and the Moderate Resolution Imaging Spectroradiometer (MODIS) sensors, aerosol retrievals from the Aerosol Robotic Network (AERONET) and attenuated backscatter coefficients from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) mission to ascertain misplacement of plume height by the model.

  8. Retrieval of composition and size distribution of stratospheric aerosols with the SAGE II satellite experiment

    NASA Technical Reports Server (NTRS)

    Yue, Glenn K.; Mccormick, M. P.; Chu, W. P.

    1986-01-01

    The SAGE II satellite system was launched on October 5, 1984. It has seven radiometric channels and is beginning to provide water vapor, NO2, and O3 concentration profiles and aerosol extinction profiles at a minimum of three wavelengths. A simple, fast and operational method of retrieving characteristics of stratospheric aerosols from the water vapor and three-wavelength aerosol extinction profiles is proposed. Some examples are given to show the practicality of the scheme. Possible sources of error for the retrieved values and the limitation of the proposed method are discussed. This method may also prove applicable to the study of aerosol characteristics in other multispectral extinction measurements.

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

    NASA Astrophysics Data System (ADS)

    Lolli, Simone; Sauvage Laurent, Laurent

    2010-05-01

    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

  10. Secondary extinctions of biodiversity.

    PubMed

    Brodie, Jedediah F; Aslan, Clare E; Rogers, Haldre S; Redford, Kent H; Maron, John L; Bronstein, Judith L; Groves, Craig R

    2014-12-01

    Extinctions beget further extinctions when species lose obligate mutualists, predators, prey, or hosts. Here, we develop a conceptual model of species and community attributes affecting secondary extinction likelihood, incorporating mechanisms that buffer organisms against partner loss. Specialized interactors, including 'cryptic specialists' with diverse but nonredundant partner assemblages, incur elevated risk. Risk is also higher for species that cannot either evolve new traits following partner loss or obtain novel partners in communities reorganizing under changing environmental conditions. Partner loss occurs alongside other anthropogenic impacts; multiple stressors can circumvent ecological buffers, enhancing secondary extinction risk. Stressors can also offset each other, reducing secondary extinction risk, a hitherto unappreciated phenomenon. This synthesis suggests improved conservation planning tactics and critical directions for research on secondary extinctions.

  11. Regional characteristics of the relationship between columnar AOD and surface PM2.5: Application of lidar aerosol extinction profiles over Baltimore-Washington Corridor during DISCOVER-AQ

    NASA Astrophysics Data System (ADS)

    Chu, D. Allen; Ferrare, Richard; Szykman, James; Lewis, Jasper; Scarino, Amy; Hains, Jennifer; Burton, Sharon; Chen, Gao; Tsai, Tzuchin; Hostetler, Chris; Hair, Johnathan; Holben, Brent; Crawford, James

    2015-01-01

    The first field campaign of DISCOVER-AQ (Deriving Information on Surface conditions from COlumn and VERtically resolved observations relevant to Air Quality) took place in July 2011 over Baltimore-Washington Corridor (BWC). A suite of airborne remote sensing and in-situ sensors was deployed along with ground networks for mapping vertical and horizontal distribution of aerosols. Previous researches were based on a single lidar station because of the lack of regional coverage. This study uses the unique airborne HSRL (High Spectral Resolution Lidar) data to baseline PM2.5 (particulate matter of aerodynamic diameter less than 2.5 μm) estimates and applies to regional air quality with satellite AOD (Aerosol Optical Depth) retrievals over BWC (∼6500 km2). The linear approximation takes into account aerosols aloft above AML (Aerosol Mixing Layer) by normalizing AOD with haze layer height (i.e., AOD/HLH). The estimated PM2.5 mass concentrations by HSRL AOD/HLH are shown within 2 RMSE (Root Mean Square Error ∼9.6 μg/m3) with correlation ∼0.88 with the observed over BWC. Similar statistics are shown when applying HLH data from a single location over the distance of 100 km. In other words, a single lidar is feasible to cover the range of 100 km with expected uncertainties. The employment of MPLNET-AERONET (MicroPulse Lidar NETwork - AErosol RObotic NETwork) measurements at NASA GSFC produces similar statistics of PM2.5 estimates as those derived by HSRL. The synergy of active and passive remote sensing aerosol measurements provides the foundation for satellite application of air quality on a daily basis. For the optimal range of 10 km, the MODIS-estimated PM2.5 values are found satisfactory at 27 (out of 36) sunphotometer locations with mean RMSE of 1.6-3.3 μg/m3 relative to PM2.5 estimated by sunphotometers. The remaining 6 of 8 marginal sites are found in the coastal zone, for which associated large RMSE values ∼4.5-7.8 μg/m3 are most likely due to

  12. Assessing Aerosol Mixed Layer Heights from the NASA Larc Airborne High Spectral Resolution Lidar (HSRL) during the Discover-AQ Field Campaigns

    NASA Astrophysics Data System (ADS)

    Scarino, A. J.; Ferrare, R. A.; Burton, S. P.; Hostetler, C. A.; Hair, J. W.; Rogers, R. R.; Berkoff, T.; Sawamura, P.; Collins, J. E., Jr.; Seaman, S. T.; Cook, A. L.; Harper, D. B.; Follette-Cook, M. B.; daSilva, A.; Randles, C. A.

    2014-12-01

    The first- and second-generation NASA airborne High Spectral Resolution Lidars (HSRL-1 and HSRL-2) have been deployed on board the NASA Langley Research Center King Air aircraft during the Deriving Information on Surface Conditions from Column and VERtically Resolved Observations Relevant to Air Quality (DISCOVER-AQ) field campaigns. These included deployments during July 2011 over Washington, D.C. and Baltimore, MD, during January and February 2013 over the San Joaquin Valley of California, during September 2013 over Houston, TX and during July and August 2014 over Denver, CO. Measurements of aerosol extinction, backscatter, and depolarization are available from both HSRL-1 and HSRL-2 in coordination with other participating research aircraft and ground sites. These measurements constitute a diverse data set for use in characterizing the spatial and temporal distribution of aerosols, aerosol optical thickness (AOT), as well as the mixed layer (ML) height. Analysis of the ML height at these four locations is presented, including temporal and horizontal variability and comparisons between land and water, including the Chesapeake Bay and Galveston Bay. Using the ML heights, the distribution of AOT relative to the ML heights is determined, which is relevant for assessing the long-range transport of aerosols. The ML heights are also used to help relate column AOT measurements and extinction profiles to surface PM2.5 concentrations. The HSRL ML heights are also used to evaluate the performance in simulating the temporal and spatial variability of ML heights from both chemical regional models and global forecast models.

  13. Gradual extinction reduces reinstatement

    PubMed Central

    Shiban, Youssef; Wittmann, Jasmin; Weißinger, Mara; Mühlberger, Andreas

    2015-01-01

    The current study investigated whether gradually reducing the frequency of aversive stimuli during extinction can prevent the return of fear. Thirty-one participants of a three-stage procedure (acquisition, extinction and a reinstatement test on day 2) were randomly assigned to a standard extinction (SE) and gradual extinction (GE) procedure. The two groups differed only in the extinction procedure. While the SE group ran through a regular extinction process without any negative events, the frequency of the aversive stimuli during the extinction phase was gradually reduced for the GE group. The unconditioned stimulus (US) was an air blast (5 bar, 10 ms). A spider and a scorpion were used as conditioned stimuli (CS). The outcome variables were contingency ratings and physiological measures (skin conductance response, SCR and startle response). There were no differences found between the two groups for the acquisition and extinction phases concerning contingency ratings, SCR, or startle response. GE compared to SE significantly reduced the return of fear in the reinstatement test for the startle response but not for SCR or contingency ratings. This study was successful in translating the findings in rodent to humans. The results suggest that the GE process is suitable for increasing the efficacy of fear extinction. PMID:26441581

  14. Mass extinction: a commentary.

    PubMed

    Raup, D M

    1987-01-01

    Four neocatastrophist claims about mass extinction are currently being debated; they are that: 1, the late Cretaceous mass extinction was caused by large body impact; 2, as many as five other major extinctions were caused by impact; 3, the timing of extinction events since the Permian is uniformly periodic; and 4, the ages of impact craters on Earth are also periodic and in phase with the extinctions. Although strongly interconnected the four claims are independent in the sense that none depends on the others. Evidence for a link between impact and extinction is strong but still needs more confirmation through bed-by-bed and laboratory studies. An important area for future research is the question of whether extinction is a continuous process, with the rate increasing at times of mass extinctions, or whether it is episodic at all scales. If the latter is shown to be generally true, then species are at risk of extinction only rarely during their existence and catastrophism, in the sense of isolated events of extreme stress, is indicated. This is line of reasoning can only be considered an hypothesis for testing. In a larger context, paleontologists may benefit from a research strategy that looks to known Solar System and Galactic phenomena for predictions about environmental effects on earth. The recent success in the recognition of Milankovitch Cycles in the late Pleistocene record is an example of the potential of this research area.

  15. Mass extinction: a commentary

    NASA Technical Reports Server (NTRS)

    Raup, D. M.

    1987-01-01

    Four neocatastrophist claims about mass extinction are currently being debated; they are that: 1, the late Cretaceous mass extinction was caused by large body impact; 2, as many as five other major extinctions were caused by impact; 3, the timing of extinction events since the Permian is uniformly periodic; and 4, the ages of impact craters on Earth are also periodic and in phase with the extinctions. Although strongly interconnected the four claims are independent in the sense that none depends on the others. Evidence for a link between impact and extinction is strong but still needs more confirmation through bed-by-bed and laboratory studies. An important area for future research is the question of whether extinction is a continuous process, with the rate increasing at times of mass extinctions, or whether it is episodic at all scales. If the latter is shown to be generally true, then species are at risk of extinction only rarely during their existence and catastrophism, in the sense of isolated events of extreme stress, is indicated. This is line of reasoning can only be considered an hypothesis for testing. In a larger context, paleontologists may benefit from a research strategy that looks to known Solar System and Galactic phenomena for predictions about environmental effects on earth. The recent success in the recognition of Milankovitch Cycles in the late Pleistocene record is an example of the potential of this research area.

  16. Absorbing aerosols over Asia: A Geophysical Fluid Dynamics Laboratory general circulation model sensitivity study of model response to aerosol optical depth and aerosol absorption

    NASA Astrophysics Data System (ADS)

    Randles, C. A.; Ramaswamy, V.

    2008-11-01

    Forcing by absorbing atmospheric black carbon (BC) tends to heat the atmosphere, cool the surface, and reduce the surface latent and sensible heat fluxes. BC aerosol can have a large impact on regional climates and the hydrologic cycle. However, significant uncertainties remain concerning the increases in (1) the total amount of all aerosol species and (2) the amount of aerosol absorption that may have occurred over the 1950-1990 period. Focusing on south and east Asia, the sensitivity of a general circulation model's climate response (with prescribed sea surface temperatures and aerosol distributions) to such changes is investigated by considering a range of both aerosol absorption and aerosol extinction optical depth increases. We include direct and semidirect aerosol effects only. Precipitation changes are less sensitive to changes in aerosol absorption optical depth at lower aerosol loadings. At higher-extinction optical depths, low-level convergence and increases in vertical velocity overcome the stabilizing effects of absorbing aerosols and enhance the monsoonal circulation and precipitation in northwestern India. In contrast, the presence of increases in only scattering aerosols weakens the monsoonal circulation and inhibits precipitation here. Cloud amount changes can enhance or counteract surface solar flux reduction depending on the aerosol loading and absorption, with the changes also influencing the surface temperature and the surface energy balance. The results have implications for aerosol reduction strategies in the future that seek to mitigate air pollution concerns. At higher optical depths, if absorbing aerosol is present, reduction of scattering aerosol alone has a reduced effect on precipitation changes, implying that reductions in BC aerosols should be undertaken at the same time as reductions in sulfate aerosols.

  17. Development of a global backscatter model for NASA's laser atmospheric wind sounder

    NASA Technical Reports Server (NTRS)

    Bowdle, David; Collins, Laurie; Mach, Douglas; Mcnider, Richard; Song, Aaron

    1992-01-01

    During the Contract Period April 1, 1989, to September 30, 1992, the Earth Systems Science Laboratory (ESSL) in the Research Institute at the University of Alabama in Huntsville (UAH) conducted a program of basic research on atmospheric backscatter characteristics, leading to the development of a global backscatter model. The ESSL research effort was carried out in conjunction with the Earth System Observing Branch (ES43) at the National Aeronautics and Space Administration (NASA) Marshall Space Flight Center, as part of NASA Contract NAS8-37585 under the Atmospheric Dynamics Program at NASA Headquarters. This research provided important inputs to NASA's GLObal Backscatter Experiment (GLOBE) program, especially in the understanding of global aerosol life cycles, and to NASA's Doppler Lidar research program, especially the development program for their prospective space-based Laser Atmospheric Wind Sounder (LAWS).

  18. SAGE II aerosol data validation and initial data use - An introduction and overview

    NASA Technical Reports Server (NTRS)

    Russell, P. B.; Mccormick, M. P.

    1989-01-01

    The process of validating data from the Stratospheric Aerosol and Gas Experiment (SAGE) II and the initial use of the validated data are reviewed. The instruments developed for the SAGE II, the influence of the eruption of El Chichon on the global stratospheric aerosol, and various data validation experiments are discussed. Consideration is given to methods for deriving aerosol physical and optical properties from SAGE II extinction data and for inferring particle size distribution moments from SAGE II spectral extinction values.

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

    SciTech Connect

    Richard A. Ferrare; David D. Turner

    2011-09-01

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

  20. Aerosol vertical distribution characteristics over the Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Deng, Z. Q.; Han, Y. X.; Zhao, Q.; Li, J.

    2014-03-01

    The Stratospheric Aerosol and Gas Experiment II (SAGE II) aerosol products are widely used in climatic characteristic studies and stratospheric aerosol pattern research. Some SAGE II products, e.g., temperature, aerosol surface area density, 1020 nm aerosol extinction coefficient and dust storm frequency, from ground-based observations were analysed from 1984 to 2005. This analysis explored the time and spatial variations of tropospheric and stratospheric aerosols on the Tibet Plateau. The stratospheric aerosol extinction coefficient increased more than two orders of magnitude because of a large volcanic eruption. However, the tropospheric aerosol extinction coefficient decreased over the same period. Removing the volcanic eruption effect, the correlation coefficient for stratospheric AOD (Aerosol Optical Depth) and tropospheric AOD was 0.197. Moreover, the correlation coefficient for stratospheric AOD and dust storm frequency was 0.315. The maximum stratospheric AOD was attained in January, the same month as the tropospheric AOD, when the Qaidam Basin was the centre of low tropospheric AOD and the large mountains coincided with high stratospheric AOD. The vertical structure generated by westerly jet adjustment and the high altitude of the underlying surface of the Tibetan Plateau were important factors affecting winter stratospheric aerosols.