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Sample records for aerosol backscatter profiles

  1. Multi-wavelength profiles of aerosol backscatter over Lauder, New Zealand, 24 November 1992

    NASA Astrophysics Data System (ADS)

    McKenzie, R. L.; Rosen, J. M.; Kjome, N. T.; McGee, T. J.; Gross, M. R.; Singh, U. N.; Ferrare, R. F.; Kimvilakani, P.; Uchino, O.; Nagai, T.

    1994-05-01

    Simultaneous profiles of aerosol backscatter ratio were measured over Lauder, New Zealand (45 deg S, 170 deg E) on the night of November 24, 1992. Instrumentation comprised two complementary lidar systems and a backscattersonde, to give measurements at wavelengths 351, 490, 532, and 940 nm. The data from the lidars and the backscattersonde were self-consistent, enabling the wavelength dependence of aerosol backscatter to be determined as a function of altitude. This wavelength-dependence is a useful parameter in radiative transfer calculations. In the stratosphere, the average wavelength exponent between 351 and 940 nm was -1.23 +/- 0.1, which was in good agreement with values derived from measured physical properties of aerosols.

  2. Multi-wavelength profiles of aerosol backscatter over Lauder, New Zealand, 24 November 1992

    NASA Technical Reports Server (NTRS)

    Mckenzie, R. L.; Rosen, J. M.; Kjome, N. T.; Mcgee, T. J.; Gross, M. R.; Singh, U. N.; Ferrare, R. F.; Kimvilakani, P.; Uchino, O.; Nagai, T.

    1994-01-01

    Simultaneous profiles of aerosol backscatter ratio were measured over Lauder, New Zealand (45 deg S, 170 deg E) on the night of November 24, 1992. Instrumentation comprised two complementary lidar systems and a backscattersonde, to give measurements at wavelengths 351, 490, 532, and 940 nm. The data from the lidars and the backscattersonde were self-consistent, enabling the wavelength dependence of aerosol backscatter to be determined as a function of altitude. This wavelength-dependence is a useful parameter in radiative transfer calculations. In the stratosphere, the average wavelength exponent between 351 and 940 nm was -1.23 +/- 0.1, which was in good agreement with values derived from measured physical properties of aerosols.

  3. 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.

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

    NASA Technical Reports Server (NTRS)

    Ferrare, R. A.; Turner, D. D.; Melfi, S. H.; Whiteman, D. N.; Schwenner, G.; Evans, K. D.; Goldsmith, J. E. M.; Tooman, T.

    1998-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

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

  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. 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.

  8. Comparison of Aerosol Backscatter and Extinction Profiles Based on the Earlinet Database and the Single Calculus Chain for Thessaloniki Greece (2001-2014)

    NASA Astrophysics Data System (ADS)

    Voudouri, K.; Siomos, N.; Giannakaki, E.; Amiridis, V.; d'Amico, G.; Balis, D. S.

    2016-06-01

    Aerosol backscatter and extinction coefficient profiles derived by the Single Calculus Chain (SCC) algorithm, which was developed within the European Aerosol Research Lidar Network (EARLINET) are compared with profiles derived by the operational inversion algorithm of Thessaloniki. Measurements performed during the period 2001-2014, that have already been uploaded in the EARLINET database, are considered in this study. The objective of this study is to verify, for the case of Thessaloniki, the consistency of the climatology of the aerosol profiles based on SCC and the EARLINET database data respectively. In this paper we show example comparisons for each lidar product submitted in the official database.

  9. Design and performance measurements of an airborne aerosol backscatter lidar

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

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

  10. 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.

  11. 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.

  12. Retrieval of aerosol backscatter and extinction from airborne coherent Doppler wind lidar measurements

    NASA Astrophysics Data System (ADS)

    Chouza, F.; Reitebuch, O.; Groß, S.; Rahm, S.; Freudenthaler, V.; Toledano, C.; Weinzierl, B.

    2015-07-01

    A novel method for calibration and quantitative aerosol optical property retrieval from Doppler wind lidars (DWLs) is presented in this work. Due to the strong wavelength dependence of the atmospheric molecular backscatter and the low sensitivity of the coherent DWLs to spectrally broad signals, calibration methods for aerosol lidars cannot be applied to coherent DWLs usually operating at wavelengths between 1.5 and 2 μm. Instead, concurrent measurements of an airborne DWL at 2 μm and the POLIS ground-based aerosol lidar at 532 nm are used in this work, in combination with sun photometer measurements, for the calibration and retrieval of aerosol backscatter and extinction profiles at 532 nm. The proposed method was applied to measurements from the SALTRACE experiment in June-July 2013, which aimed at quantifying the aerosol transport and change in aerosol properties from the Sahara desert to the Caribbean. The retrieved backscatter and extinction coefficient profiles from the airborne DWL are within 20 % of POLIS aerosol lidar and CALIPSO satellite measurements. Thus the proposed method extends the capabilities of coherent DWLs to measure profiles of the horizontal and vertical wind towards aerosol backscatter and extinction profiles, which is of high benefit for aerosol transport studies.

  13. Atmospheric aerosol backscatter measurements using a tunable coherent CO2 lidar

    NASA Technical Reports Server (NTRS)

    Menzies, R. T.; Kavaya, M. J.; Flamant, P. H.; Haner, D. A.

    1984-01-01

    Measurements of atmospheric aerosol backscatter coefficients, using a coherent CO2 lidar at 9.25- and 10.6-micron wavelengths, are described. Vertical profiles of the volume backscatter coefficient beta have been measured to a 10-km altitude over the Pasadena, CA, region. These measurements indicate a wide range of variability in beta both in and above the local boundary layer. Certain profiles also indicate a significant enhancement in beta at the 9.25-micron wavelength compared with beta at the 10.6-micron wavelength, which possibly indicates a major contribution to the volume backscatter from ammonium sulfate aerosol particles.

  14. 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.

  15. 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.

  16. Raman lidar measurements of aerosol extinction and backscattering: 1. Methods and comparisons

    NASA Astrophysics Data System (ADS)

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

    1998-08-01

    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 0.015 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 0.1 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.

  17. Atmospheric backscatter vertical profiles at 9.2 and 10.6 microns - A comparative study

    NASA Technical Reports Server (NTRS)

    Ancellet, Gerard M.; Menzies, Robert T.; Tratt, David M.

    1988-01-01

    The paper reports a series of atmospheric aerosol backscatter measurements at two widely spaced CO2 laser wavelengths: 9.25 and 10.6 microns. Comparisons are made between backscatter coefficient profiles at these two wavelengths up to 20-km altitude. Measurements such as those reported here can be used to assess the feasibility of coherent CO2 lidar for wind measurements, and they also provide a partial test of backscatter model predictions.

  18. Aerosol optical properties of the free troposphere: Tropospheric backscatter climatology

    NASA Astrophysics Data System (ADS)

    Rosen, James M.

    1994-12-01

    A unique ensemble of aerosol sensors (backscattersondes, nephelometers and particle counters) has been assembled during the course of this research to obtain new measurements relating to the optical properties of aerosols in the atmosphere, especially in the free troposphere. A knowledge of the aerosol extinction-to-backscatter ratio has been greatly enhanced as a result of this project and the inference of representative values along with the range of variation is now possible. Agreement between the optical model results and actual measurements appears to be quite satisfactory. An initial climatology of aerosol backscatter in the free troposphere has been developed and is in general agreement with results and inferences from global remote sensing instruments. However, the data from remote sensors may indicate a larger influence of volcanic aerosols on the upper troposphere than actually exists. Further work with high resolution soundings is needed to fully resolve this issue.

  19. Backscatter signatures of biological aerosols in the infrared.

    PubMed

    Thrush, Evan; Salciccioli, Nicolas; Brown, David M; Siegrist, Karen; Brown, Andrea M; Thomas, Michael E; Boggs, Nathan; Carter, Christopher C

    2012-04-20

    To develop a deeper understanding of the optical signatures of both biological aerosols and potential interferents, we made field measurements of optical cross sections and compared them to model-based predictions. We measured aerosol cross sections by conducting a hard-target calibration of a light detection and ranging system (LIDAR) based on the Frequency Agile Laser (FAL). The elastic backscatter cross sections are estimated at 19 long-wave infrared (LWIR) wavelengths spanning the range from 9.23 to 10.696 μm. The theoretical modeling of the elastic backscatter cross sections is based on the measured refractive index and size distribution of the aerosols, which are used as inputs into Mie calculations. Both model calculations and experimental measurements show good agreement and also indicate the presence of spectral features based on single particle absorption in the backscatter cross sections that can be used as a basis for discrimination for both standoff and point sensors. PMID:22534887

  20. Aerosol Lidar for the Relative Backscatter Amplification Measurements

    NASA Astrophysics Data System (ADS)

    Razenkov, Igor A.; Banakh, Victor A.; Nadeev, Alexander I.

    2016-06-01

    Backscatter amplification presents only in a turbulent atmosphere, when the laser beam is propagates twice through the same inhomogeneities. We proposed technical solution to detect backscatter amplification. An aerosol micro pulse lidar with a beam expansion via receiving telescope was built to study this effect. Our system allows simultaneous detection of two returns from the same scattering volume: exactly on the axis of the laser beam and off the axis.

  1. 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.

  2. 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.

  3. Synergetic technique combining elastic backscatter lidar data and sunphotometer AERONET inversion for retrieval by layer of aerosol optical and microphysical properties.

    PubMed

    Cuesta, Juan; Flamant, Pierre H; Flamant, Cyrille

    2008-09-01

    We present a so-called lidar and almucantar (LidAlm) algorithm that combines information provided by standard elastic backscatter lidar (i.e., calibrated attenuated backscatter coefficient profile at one or two wavelengths) and sunphotometer AERONET inversion of almucantar like measurements (i.e., column-integrated aerosol size distribution and refractive index). The purpose of the LidAlm technique is to characterize the atmospheric column by its different aerosol layers. These layers may be distinct or partially mixed, and they may contain different aerosol species (e.g., urban, desert, or biomass burning aerosols). The LidAlm synergetic technique provides the extinction and backscatter coefficient profiles, particle size distributions, and backscatter-to-extinction ratios for each aerosol layer. We present the LidAlm procedure and sensitivity studies. The applications are illustrated with examples of actual atmospheric conditions encountered in the Paris area. PMID:18758531

  4. 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.

  5. Aerosol Backscatter and Extinction Retrieval from Airborne Coherent Doppler Wind Lidar Measurements

    NASA Astrophysics Data System (ADS)

    Chouza, F.; Reitebuch, O.; Groß, S.; Rahm, S.; Freudenthaler, V.; Toledano, C.; Weinzierl, B.

    2016-06-01

    A novel method for coherent Doppler wind lidars (DWLs) calibration is shown in this work. Concurrent measurements of a ground based aerosol lidar operating at 532 nm and an airborne DWL at 2 μm are used in combination with sun photometer measurements for the retrieval of backscatter and extinction profiles. The presented method was successfully applied to the measurements obtained during the Saharan Aerosol Long-range Transport and Aerosol-Cloud-Interaction Experiment (SALTRACE: http://www.pa.op.dlr.de/saltrace), which aimed to characterize the Saharan dust long range transport between Africa and the Caribbean.

  6. 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.

  7. Potential of lidar backscatter data to estimate solar aerosol radiative forcing

    NASA Astrophysics Data System (ADS)

    Wendisch, Manfred; Müller, Detlef; Mattis, Ina; Ansmann, Albert

    2006-02-01

    The potential to estimate solar aerosol radiative forcing (SARF) in cloudless conditions from backscatter data measured by widespread standard lidar has been investigated. For this purpose 132 days of sophisticated ground-based Raman lidar observations (profiles of particle extinction and backscatter coefficients at 532 nm wavelength) collected during two campaigns [the European Aerosol Research Lidar Network (EARLINET) and the Indian Ocean Experiment (INDOEX)] were analyzed. Particle extinction profiles were used as input for radiative transfer simulations with which to calculate the SARF, which then was plotted as a function of the column (i.e., height-integrated) particle backscatter coefficient (betac). A close correlation between the SARF and betac was found. SARF-betac parameterizations in the form of polynomial fits were derived that exhibit an estimated uncertainty of +/-(10-30)%. These parameterizations can be utilized to analyze data of upcoming lidar satellite missions and for other purposes. The EARLINET-based parameterizations can be applied to lidar measurements at mostly continental, highly industrialized sites with limited maritime influence (Europe, North America), whereas the INDOEX parameterizations rather can be employed in polluted maritime locations, e.g., coastal regions of south and east Asia.

  8. Potential of lidar backscatter data to estimate solar aerosol radiative forcing.

    PubMed

    Wendisch, Manfred; Müller, Detlef; Mattis, Ina; Ansmann, Albert

    2006-02-01

    The potential to estimate solar aerosol radiative forcing (SARF) in cloudless conditions from backscatter data measured by widespread standard lidar has been investigated. For this purpose 132 days of sophisticated ground-based Raman lidar observations (profiles of particle extinction and backscatter coefficients at 532 nm wavelength) collected during two campaigns [the European Aerosol Research Lidar Network (EARLINET) and the Indian Ocean Experiment (INDOEX)] were analyzed. Particle extinction profiles were used as input for radiative transfer simulations with which to calculate the SARF, which then was plotted as a function of the column (i.e., height-integrated) particle backscatter coefficient (beta(c)). A close correlation between the SARF and beta(c) was found. SARF-beta(c) parameterizations in the form of polynomial fits were derived that exhibit an estimated uncertainty of +/-(10-30)%. These parameterizations can be utilized to analyze data of upcoming lidar satellite missions and for other purposes. The EARLINET-based parameterizations can be applied to lidar measurements at mostly continental, highly industrialized sites with limited maritime influence (Europe, North America), whereas the INDOEX parameterizations rather can be employed in polluted maritime locations, e.g., coastal regions of south and east Asia. PMID:16485690

  9. Aerosol profiling by calibrated ceilometer data

    NASA Astrophysics Data System (ADS)

    Geiß, Alexander; Wiegner, Matthias

    2015-04-01

    Recently, networks of automated single-wavelength backscatter lidars ("ceilometers") were implemented, primarily by weather services. As a consequence, the potential of ceilometers to quantitatively determine the spatiotemporal distribution of atmospheric aerosols was investigated, to derive mixing layer heights for air quality studies and to assess optical properties. The main issues are the limited signal-to-noise ratio and the inherent problems of the calibration. We have studied several approaches for calibrating ceilometers, based on different numerical solutions and on auxiliary data of different remote sensing techniques. As a result, the backscatter coefficient can be determined with a relative accuracy of typically 10% and a time resolution in the order of 5 minutes. This parameter is used to estimate the mixing layer height by applying different techniques of averaging and pattern recognition. In this context, it is assumed that aerosols are a good tracer for the thermodynamic stratification of the troposphere. Our algorithm is fully automated and was tested for several commercially available ceilometers. For this purpose, a simplified version for non-calibrated ceilometers, based on the so called range corrected signal, was additionally developed. We used data of the CHM15k-x ceilometer (manufactured by Jenoptik) from more than 5 years of continuous operation by the LMU-MIM in Munich (Germany) to establish climatologies of mixing layer heights (MLH), cloud cover, cloud heights and vertical profiles of the backscatter coefficient. Among others, the mean diurnal cycle and the interannual variability of the MLH for different months were determined. Ceilometer derived MLH were also used to validate different parameterization of chemistry transport models and to validate forecasts of the dispersion of aerosol layers. For the latter applications backscatter coefficients are required. That means, a calibration of the ceilometers is mandatory.

  10. 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.

  11. 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

  12. [Obtaining aerosol backscattering coefficient using pure rotational Raman-Mie scattering spectrum].

    PubMed

    Rong, Wei; Chen, Si-Ying; Zhang, Yin-Chao; Chen, He; Guo, Pan

    2012-11-01

    Both the traditional Klett and Fernald methods used to obtain atmospheric aerosol backscattering coefficient require the hypothesis of relationship between the extinction coefficient and backscattering coefficient, and this will bring error. According to the theory that the pure rotational Raman backscattering coefficient is only related to atmospheric temperature and pressure, a new method is presented for inverting aerosol backscattering coefficient, which needed the intensity of elastic scattering and rotational Raman combined with atmospheric temperature and pressure obtained with the sounding balloons in this article. This method can not only eliminate the errors of the traditional Klett and Fernald methods caused by the hypothesis, but also avoid the error caused by the correction of the overlap. Finally, the aerosol backscattering coefficient was acquired by using this method and the data obtained via the Raman-Mie scattering Lidar of our lab. And the result was compared with that of Klett and Fernald. PMID:23387171

  13. Powerful eyesafe infrared aerosol lidar: Application of stimulated Raman backscattering of 1.06 micron radiation

    NASA Astrophysics Data System (ADS)

    Carnuth, W.; Trickl, T.

    1994-11-01

    Usually, lidar investigations of light backscattering and extinction by aerosols are most commonly carried out near infrared. In the study, the background noise from Rayleigh backscattering is substantially reduced, there is a sufficiently large number of wavelength windows with high atmospheric transmittance, powerful pulsed laser sources exist, and efficient detectors are available.

  14. 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.

  15. 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

    Aerosol backscatter measurements using two continuous wave CO2 Doppler lidars were obtained over western North America and the Pacific Ocean during a 1995 NASA airborne mission. 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)/m.sr, consistent with previous lidar datasets.

  16. Comparison of Predicted and Measured 2 Micron Aerosol Backscatter from the 1998 ACLAIM Flight Tests

    NASA Technical Reports Server (NTRS)

    Bowdle, David A.; Hannon, Stephen M.; Bogue, Rodney K.

    1999-01-01

    The 1998 Airborne Coherent Lidar for Advanced Inflight Measurements (ACLAIM) flight tests were conducted aboard a well-instrumented research aircraft. This paper presents comparisons of 2 micrometer aerosol backscatter coefficient predictions from aerosol sampling data and mie scattering codes with those produced by the ACLAIM instrument.

  17. Comparison of CO2 backscatter using Mie theory from aerosol measurements over Pacific Basin with lidar data

    NASA Technical Reports Server (NTRS)

    Srivastava, Vandana; Clarke, Antony D.; Porter, John; Jarzembski, Maurice; Bowdle, David

    1991-01-01

    Results of a comparison of aerosol backscatter with measurements over the Pacific Basin obtained from the CW CO2 lidars are presented. Both the Laser Optical Particle Counter (POPC) and CW CO2 lidars performed measurements at the flight level close to the aircraft and measured the same air mass. From the number distributions measured during a flight over Tokyo in June 1990, the backscatter coefficient for each component is calculated by integrating the differential backscatter. Fifteen sets of number distributions measured by the LOPC during the flight are used to predict aerosol backscatter. The backscatter from microphysics of the aerosols obtained from the LOPC and from the lidar measurements are in good agreement. It is concluded that the size distribution and composition of the aerosols can change dramatically as a function of altitude and location. The magnitude of the aerosol backscatter can vary by over three orders of magnitude from clear air to an aerosol layer.

  18. 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.

  19. 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.

  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. A study on the aerosol extinction-to-backscatter ratio with combination of micro-pulse LIDAR and MODIS over Hong Kong

    NASA Astrophysics Data System (ADS)

    He, Q. S.; Li, C. C.; Mao, J. T.; Lau, A. K. H.; Li, P. R.

    2006-08-01

    The aerosol extinction-to-backscatter ratio is an important parameter for inverting LIDAR signals in the LIDAR equation. It is a complicated function of the aerosol microphysical characteristics. In this paper, a method to retrieve the column-averaged aerosol extinction-to-backscatter ratio by constraining the aerosol optical depths (AOD) from a Micro-pulse LIDAR (MPL) by the AOD measurements from the Moderate Resolution Imaging Spectroradiometer (MODIS) is presented. Both measurements were taken on cloud free days between 1 May 2003 and 30 June 2004 over Hong Kong, a coastal city in south China. Simultaneous measurements of aerosol scattering coefficients with a forward scattering visibility sensor are compared with the LIDAR retrieval of aerosol extinction coefficients. The data are then analyzed to determine seasonal trends of the aetrosol extinction-to-backscatter ratio. In addition, the relationships between the extinction-to-backscatter ratio and wind conditions as well as other aerosol microphysical parameters are presented. The mean aerosol extinction-to-backscatter ratio for the whole period was found to be 29.1±5.8 sr, with a minimum of 18 sr in July 2003 and a maximum of 44 sr in March 2004. The ratio is lower in summer because of the dominance of oceanic aerosols in association with the prevailing southwesterly monsoon. In contrast, relatively larger ratios are noted in spring and winter because of the increased impact of local and regional industrial pollutants associated with the northerly monsoon. The extended LIDAR measurements over Hong Kong provide not only a more accurate retrieval of aerosol extinction coefficient profiles, but also significant substantial information for air pollution and climate studies in the region.

  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. Particle backscatter and extinction profiling with the spaceborne high-spectral-resolution Doppler lidar ALADIN: methodology and simulations.

    PubMed

    Ansmann, Albert; Wandinger, Ulla; Le Rille, Olivier; Lajas, Dulce; Straume, Anne Grete

    2007-09-10

    The European Space Agency will launch the Atmospheric Laser Doppler Instrument (ALADIN) for global wind profile observations in the near future. The potential of ALADIN to measure the optical properties of aerosol and cirrus, as well, is investigated based on simulations. A comprehensive data analysis scheme is developed that includes (a) the correction of Doppler-shifted particle backscatter interference in the molecular backscatter channels (cross-talk effect), (b) a procedure that allows us to check the quality of the cross-talk correction, and (c) the procedures for the independent retrieval of profiles of the volume extinction and backscatter coefficients of particles considering the height-dependent ALADIN signal resolution. The error analysis shows that the particle backscatter and extinction coefficients, and the corresponding extinction-to-backscatter ratio (lidar ratio), can be obtained with an overall (systematic+statistical) error of 10%-15%, 15%-30%, and 20%-35%, respectively, in tropospheric aerosol and dust layers with extinction values from 50 to 200 Mm(-1); 700-shot averaging (50 km horizontal resolution) is required. Vertical signal resolution is 500 m in the lower troposphere and 1000 m in the free troposphere. In cirrus characterized by extinction coefficients of 200 Mm(-1) and an optical depth of >0.2, backscatter coefficients, optical depth, and column lidar ratios can be obtained with 25%-35% relative uncertainty and a horizontal resolution of 10 km (140 shots). In the stratosphere, only the backscatter coefficient of aerosol layers and polar stratospheric clouds can be retrieved with an acceptable uncertainty of 15%-30%. Vertical resolution is 2000 m. PMID:17846655

  4. 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.

  5. 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.

  6. 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.

  7. Backscatter measurements of aerosolized CB simulants with a frequency agile CO2 lidar

    NASA Astrophysics Data System (ADS)

    Vanderbeek, Richard; Gurton, Kristan

    2004-02-01

    A novel windowless chamber was developed to allow aerosol backscatter measurements with a frequency-agile CO2 lidar. The chamber utilizes curtains of air to contain the cloud, thus preventing the inevitable backscatter off of conventional windows from corrupting the desired measurements. This feature is critical because the CO2 lidar has a long (1 μs) pulse and the backscatter off the window cannot be temporally separated from the backscatter off the aerosol in the chamber. The chamber was designed for testing with a variety of CB simulants and interferents in both vapor and aerosol form and has been successfully shown to contain a cloud of known size, concentration, and particle size distribution for 10-15 minutes. This paper shows the results using Arizona road dust that was screened by the manufacturer into 0-3 μm and 5-10 μm particle size distributions. The measurements clearly show the effect of size distribution on the infrared backscatter coefficients as well as the dynamic nature of the size distribution for a population of aerosols. The test methodology and experimental results are presented.

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

    SciTech Connect

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

    2007-09-01

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

  9. 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).

  10. Aerosol speckle effects on atmospheric pulsed lidar backscattered signals

    NASA Technical Reports Server (NTRS)

    Murty, S. R.

    1989-01-01

    Lidar systems using atmospheric aerosols as targets exhibit return signal amplitude and power fluctuations which indicate speckle effects. The effects of refractive turbulence along the path on the aerosol speckle field propagation and on the decorrelation time are studied for coherent pulsed lidar systems.

  11. Influence of enhanced backscattering phenomenon on laser measurements of dust and aerosols content in a turbulent atmosphere

    NASA Astrophysics Data System (ADS)

    Chrzanowski, J.; Kirkiewicz, J.; Kravtsov, Yu. A.

    2002-07-01

    Influence of enhanced backscattering effect on laser measurements of dust and aerosols content in a turbulent atmosphere is discussed. It is shown that doubling of the backscattered light intensity, characteristic for enhanced backscattering leads to overestimating dust content in the air. To avoid undesirable effect of overestimation of dust and aerosols it is recommended to displace receiving aperture sidewise relatively to source and to use wider laser beam and extended receiving aperture as compared to coherence radius of the scattered wave field.

  12. 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.

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

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

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

  14. 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.

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

    NASA Astrophysics Data System (ADS)

    Warren, Russell E.; Vanderbeek, Richard G.

    2004-08-01

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

  16. Estimation of multiple-aerosol concentration and backscatter using multi-wavelength range-resolved lidar

    NASA Astrophysics Data System (ADS)

    Warren, Russell E.; Vanderbeek, Richard G.

    2007-09-01

    Previous work by the authors has produced statistically based methods for detecting, estimating and classifying aerosol materials in the atmosphere using multiple-wavelength range-resolved CO2 lidar. This work has thus far been limited to the presence of a single aerosol material at a given time within the lidar line-of-sight. Practical implementation requires the ability to detect and discriminate multiple aerosol materials present simultaneously such as smoke and dust in addition to hazardous materials. Treating mixtures of materials necessitates fundamentally different approaches from the single-material case since neither the aerosol backscatter wavelength-dependence nor the concentrations as a function of range are known. Because of this, linear processing cannot resolve the mixture data into its components unambiguously, and non-linear methods must be considered. In this paper we describe an empirical Bayes (EB) approach for resolving mixtures of aerosol into their components. The basic idea of EB is to use the same data to estimate the prior distribution of a set of parameters as that used to estimate the parameters themselves. In our case the concentration and backscatter are the parameters that are estimated with the help of a prior distribution of the backscatter. We implement the EB estimator through the EM (Expectation Maximization) algorithm. The resulting processor is applied to injections of interferent dust into data sets collected by ECBC during JBSDS testing at Dugway Proving Ground, UT in 2006.

  17. A study on aerosol extinction-to-backscatter ratio with combination of micro-pulse lidar and MODIS over Hong Kong

    NASA Astrophysics Data System (ADS)

    He, Q. S.; Li, C. C.; Mao, J. T.; Lau, A. K. H.

    2006-04-01

    The aerosol extinction-to-backscatter ratio is an important parameter for inverting LIDAR signals in the LIDAR equation. It is also a complicated function of aerosol microphysical characteristics depending on geographical and meteorological conditions. In this paper, a method to retrieve the column-averaged aerosol extinction-to-backscatter ratio by constraining the aerosol optical depths (AOD) recorded by the Moderate Resolution Imaging Spectroradiometer (MODIS) to the ones measured by a Micro-pulse LIDAR (MPL) is presented. Both measurements were taken between 1 May 2003 and 30 June 2004 over Hong Kong, a coastal city in south China. Simultaneous scattering coefficients measured by a forward scattering visibility sensor are compared with the LIDAR retrieval. The data are then analyzed in terms of monthly and seasonal trends. In addition, the relationships between the extinction-to-backscatter ratio and wind conditions as well as other aerosol microphysical parameters are also presented. The mean aerosol extinction-to-backscatter ratio for the whole period is found to be 28.9±6.1 sr, with the minimum of 12 sr in August 2003 and the maximum of 44 sr in March 2004. The ratio is lower in the summer because of the dominance of oceanic aerosols in association with the prevailing southwesterly monsoon. In contrast, relatively larger ratios are noted in spring and winter because of the increased impact of local and regional industrial pollutants associated with the northerly monsoon. The extended LIDAR measurements over Hong Kong provide not only a more accurate retrieval of aerosol extinction coefficient profiles, but also significant information for air pollution and climate studies in the region.

  18. 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".

  19. 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.

  20. 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

  1. 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

  2. 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.

  3. 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.

  4. Sensitivity of Scattering and Backscattering Coefficients to Microphysical and Chemical Properties: Weakly Absorbing Aerosol

    NASA Astrophysics Data System (ADS)

    Kassianov, E.; Barnard, J.; Pekour, M. S.; Berg, L. K.; Shilling, J.; Flynn, C. J.; Mei, F.; Jefferson, A.

    2014-12-01

    Scattering and backscattering coefficients of atmospheric aerosol are crucial parameters for numerous climate-relevant applications, including studies related to the Earth's radiation budget. Due to their strong connection to aerosol chemical and microphysical characteristics, in situ measurements have been commonly used for evaluating optical properties routines in global and regional scale models. However, these in situ measurements, including size distribution and chemical composition data, can be subject to uncertainties. Techniques for obtaining these data depend on particle size (submicron versus supermicron) and relative humidity range (dry versus wet conditions). In this study, we examine how the data uncertainties can impact the level of agreement between the calculated and measured optical properties (commonly known as optical closure). Moreover, we put forth a novel technique for inferring in parallel the effective density and real refractive index of weakly absorbing aerosols from simultaneously measured size distributions (with mobility and aerodynamic sizes), and two optical properties, namely the scattering coefficient and hemispheric backscatter fraction, measured by integrating nephelometer. We demonstrate the performance of our technique, which permits discrimination between the retrieved aerosol characteristics of sub-micron and sub-10-micron particles, using both a sensitivity study with synthetically generated inputs with random noise and a six-week case study with real measurements. These measurements cover a wide range of coastal summertime conditions observed during the recent Two-Column Aerosol Project (TCAP, http://campaign.arm.gov/tcap/) and include periods with a wide range of aerosol loading and relative humidity. Finally, we discuss how in situ data and retrievals of aerosol characteristics can be applied for model evaluation.

  5. Use of ceilometers for aerosol profile measurements: a comment from AD-Net

    NASA Astrophysics Data System (ADS)

    Jin, Yoshitaka; Kai, Kenji; Kawai, Kei; Sugimoto, Nobuo; Nishizawa, Tomoaki; Matsui, Ichiro; Shimizu, Atsushi; Batdorj, Dashdondog

    2014-11-01

    Ceilometer instruments are simple backscatter lidar systems and are usually set in airports for detecting the base of clouds. The instrument can also measure aerosol vertical distribution. Since ceilometers barely detect the molecular backscatter signals, retrieval of aerosol optical properties is an issue. This study investigates applicability of ceilometers to retrieval of optical properties. We make an idealized signal profile with the lidar ratio of 50 sr and calculate the retrieval errors caused by 30% errors of lidar ratio. In the forward inversion, useable (small error) optical properties are backscattering coefficients and the retrieval errors are less than 15% if the aerosol optical depth (AOD) is less than 0.2. The initial backscattering coefficients must be determined from other instruments (e.g., multi-wavelength lidar). Whereas in the backward inversion, if the AOD of idealized signals is larger than 1.5, extinction coefficients converge to the true value (within 5% errors), regardless of lidar ratios and initial conditions. Since there is no need for the system constant or molecular backscatter in this method, ceilometers can be an effective tool for retrieving extinction coefficients of dense aerosols in East Asia.

  6. 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.

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

    PubMed

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

    2008-01-20

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

  8. Use of rotational Raman measurements in multiwavelength aerosol lidar for evaluation of particle backscattering and extinction

    NASA Astrophysics Data System (ADS)

    Veselovskii, I.; Whiteman, D. N.; Korenskiy, M.; Suvorina, A.; Pérez-Ramírez, D.

    2015-10-01

    Vibrational Raman scattering from nitrogen is commonly used in aerosol lidars for evaluation of particle backscattering (β) and extinction (α) coefficients. However, at mid-visible wavelengths, particularly in the daytime, previous measurements have possessed low signal-to-noise ratio. Also, vibrational scattering is characterized by a significant frequency shift of the Raman component, so for the calculation of α and β information about the extinction Ångström exponent is needed. Simulation results presented in this study demonstrate that ambiguity in the choice of Ångström exponent can be the a significant source of uncertainty in the calculation of backscattering coefficients when optically thick aerosol layers are considered. Both of these issues are addressed by the use of pure-rotational Raman (RR) scattering, which is characterized by a higher cross section compared to nitrogen vibrational scattering, and by a much smaller frequency shift, which essentially removes the sensitivity to changes in the Ångström exponent. We describe a practical implementation of rotational Raman measurements in an existing Mie-Raman lidar to obtain aerosol extinction and backscattering at 532 nm. A 2.3 nm width interference filter was used to select a spectral range characterized by low temperature sensitivity within the anti-Stokes branch of the RR spectrum. Simulations demonstrate that the temperature dependence of the scattering cross section does not exceed 1.5 % in the 230-300 K range, making correction for this dependence quite easy. With this upgrade, the NASA GSFC multiwavelength Raman lidar has demonstrated useful α532 measurements and was used for regular observations. Examples of lidar measurements and inversion of optical data to the particle microphysics are given.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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

  15. 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].

  16. 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

    dimensions. HARLIE was used in a ground-based configuration in several recent field campaigns. Principal data products include aerosol backscatter profiles, boundary layer heights, entrainment zone thickness, cloud fraction as a function of altitude and horizontal wind vector profiles based on correlating the motions of clouds and aerosol structures across portions of the scan. Comparisons will be made between various cloud detecting instruments to develop a baseline performance metric.

  17. 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.

  18. Relationships between Optical Extinction, Backscatter and Aerosol Surface and Volume in the Stratosphere following the Eruption of Mt. Pinatubo

    NASA Technical Reports Server (NTRS)

    Brock, Charles A.; Jonsson, Haflidi H.; Wilson, James C.; Dye, James E.; Baumgardner, Darrel; Borrmann, Stephan; Pitts, Mike C.; Osborn, Mary T.; DeCoursey, Robert J.; Woods, David C.

    1993-01-01

    The eruption of the Mt. Pinatubo volcano in the Philippines in June 1991 has resulted in increases in the surface and mass concentrations of aerosol particles in the lower stratosphere. Airborne measurements made at midlatitudes between 15 and 21 km from August 1991 to March 1992 show that, prior to December 1991, the Pinatubo aerosol cloud varied widely in microphysical properties such as size distribution, number, surface and volume concentrations and was also spatially variable. Aerosol surface area concentration was found to be highly correlated to extinction at visible and near-infrared wavelengths throughout the measurement period. Similarly, backscatter at common lidar wavelengths was a good predictor of aerosol volume concentrations. These results support the use of satellite extinction measurements to estimate aerosol surface and of lidar measurements to estimate aerosol volume or mass if temporal changes in the relationships between the variables are considered.

  19. 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

  20. Determination of aerosol extinction coefficient profiles from LIDAR data using the optical depth solution method

    NASA Astrophysics Data System (ADS)

    Aparna, John; Satheesh, S. K.; Mahadevan Pillai, V. P.

    2006-12-01

    The LIDAR equation contains four unknown variables in a two-component atmosphere where the effects caused by both molecules and aerosols have to be considered. The inversion of LIDAR returns to retrieve aerosol extinction profiles, thus, calls for some functional relationship to be assumed between these two. The Klett's method, assumes a functional relationship between the extinction and backscatter. In this paper, we apply a different technique, called the optical depth solution, where we made use of the total optical depth or transmittance of the atmosphere along the LIDAR-measurement range. This method provides a stable solution to the LIDAR equation. In this study, we apply this technique to the data obtained using a micro pulse LIDAR (MPL, model 1000, Science and Engineering Services Inc) to retrieve the vertical distribution of aerosol extinction coefficient. The LIDAR is equipped with Nd-YLF laser at an operating wavelength of 523.5 nm and the data were collected over Bangalore. The LIDAR data are analyzed to get to weighted extinction coefficient profiles or the weighted sum of aerosol and molecular extinction coefficient profiles. Simultaneous measurements of aerosol column optical depth (at 500 nm) using a Microtops sun photometer were used in the retrievals. The molecular extinction coefficient is determined assuming standard atmospheric conditions. The aerosol extinction coefficient profiles are determined by subtracting the molecular part from the weighted extinction coefficient profiles. The details of the method and the results obtained are presented.

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

    SciTech Connect

    Ferrare, R.A.

    2000-01-09

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

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

    SciTech Connect

    FERRARE,R.A.

    2000-01-09

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

  3. 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.

  4. 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.

  5. F region electron density profile inversion from backscatter ionogram based on international reference ionosphere

    NASA Astrophysics Data System (ADS)

    Zhu, Peng; Zhou, Chen; Zhang, Yuannong; Yang, Guobin; Jiang, Chunhua; Sun, Hengqing; Cui, Xiao

    2015-07-01

    Ionospheric backscatter sounding transmits HF (3-30 MHz) radio wave obliquely into ionosphere and receives echoes backscattered from remote ground. Due to the focusing effect, the echoes form leading edge on the swept frequency backscatter ionogram (BSI). This kind of backscatter ionogram contains plentiful ionospheric information, such as electron density, radio wave propagation modes and maximum usage frequency (MUF). By inversion algorithm, the backscatter ionogram can provide two-dimensional electron density profile (EDP) down range. In this paper, we propose an ionospheric F2 region EDP inversion algorithm. By utilizing the F2 bottomside electron density profile represented by the International Reference Ionosphere (IRI) model and ray tracing techniques, this approach inverts the leading edge of the backscatter ionogram to two dimensional F region EDP. Results of validation experiments demonstrate that the inverted ionospheric EDPs show good agreement with the results of vertical ionosonde and provide reliable information of ionosphere. Thus the proposed inversion algorithm provide an effective and accurate method for achieving large scale and remote ionospheric electron density structure.

  6. Relationships between optical extinction, backscatter and aerosol surface and volume in the stratosphere following the eruption of Mt. Pinatubo

    NASA Technical Reports Server (NTRS)

    Brock, Charles A.; Jonsson, Haflidi H.; Wilson, James C.; Dye, James E.; Baumgardner, Darrel; Borrmann, Stephan; Pitts, Mike C.; Osborn, Mary T.; Decoursey, Robert J.; Woods, David C.

    1993-01-01

    The eruption of the Mt. Pinatubo volcano in the Philippines in June 1991 has resulted in increases in the surface and mass concentrations of aerosol particles in the lower stratosphere. Airborne measurements made at midlatitudes between 15 and 21 km from August 1991 to March 1992 show that, prior to December 1991, the Pinatubo aerosol cloud varied widely in microphysical properties such as size distribution, number, surface and volume concentrations and was also spatially variable. Aerosol surface area concentration was found to be highly correlated to extinction at visible and near-infrared wavelenghts throughout the measurement period. Similarly, backscatter at common lidar wavelengths was a good predictor of aerosol volume concentrations. These results support the use of satellite extinction measurements to estimate aerosol volume or mass if temporal changes in the relationships between the variables are considered.

  7. 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.

  8. 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.

  9. 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.

  10. 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

  11. 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

  12. Aerosol profiling using the ceilometer network of the German Meteorological Service

    NASA Astrophysics Data System (ADS)

    Flentje, H.; Heese, B.; Reichardt, J.; Thomas, W.

    2010-08-01

    The German Meteorological Service (DWD) operates about 52 lidar ceilometers within its synoptic observations network, covering Germany. These affordable low-power lidar systems provide spatially and temporally high resolved aerosol backscatter profiles which can operationally provide quasi 3-D distributions of particle backscatter intensity. Intentionally designed for cloud height detection, recent significant improvements allow following the development of the boundary layer and to detect denser particle plumes in the free tropospere like volcanic ash, Saharan dust or fire smoke. Thus the network builds a powerful aerosol plume alerting and tracking system. If auxiliary aerosol information is available, the particle backscatter coefficient, the extinction coefficient and even particle mass concentrations may be estimated, with however large uncertainties. Therefore, large synergistic benefit is achieved if the ceilometers are linked to existing lidar networks like EARLINET or integrated into WMO's envisioined Global Aerosol Lidar Observation Network GALION. To this end, we demonstrate the potential and limitations of ceilometer networks by means of three representative aerosol episodes over Europe, namely Sahara dust, Mediterranean fire smoke and, more detailed, the Icelandic Eyjafjoll volcano eruption from mid April 2010 onwards. The DWD (Jenoptik CHM15k) lidar ceilometer network tracked the Eyjafjoll ash layers over Germany and roughly estimated peak extinction coefficients and mass concentrations on 17 April of 4-6(± 2) 10-4 m-1 and 500-750(± 300) μg/m-3, respectively, based on co-located aerosol optical depth, nephelometer (scattering coefficient) and particle mass concentration measurements. Though large, the uncertainties are small enough to let the network suit for example as aviation advisory tool, indicating whether the legal flight ban threshold of presently 2 mg/m3 is imminent to be exceeded.

  13. Effect of particle settling on lidar profiles of long-range transported Saharan aerosols

    NASA Astrophysics Data System (ADS)

    Gasteiger, Josef; Groß, Silke

    2016-04-01

    A large amount of desert aerosol is transported in the Saharan Air Layer (SAL) westwards from Africa over the Atlantic Ocean. Lidar profiles of transported Saharan aerosol may contain some information about the vertically-resolved aerosol microphysics that could be used to characterize processes that affected the measured aerosol during transport. We present modelled lidar profiles of long-range transported Saharan aerosol assuming that initially the SAL is well-mixed and that there is no vertical mixing of air within the SAL as soon as it reaches the Atlantic. We consider Stokes gravitational settling of aerosol particles over the ocean. The lidar profiles are calculated using optical models for irregularly-shaped mineral dust particles assuming settling-induced particle removal as function of distance from the SAL top. Within the SAL we find a decrease of both the backscatter coefficients and the linear depolarization ratios with decreasing distance from the SAL top. For example, the linear depolarization ratio at a wavelength of 532nm decreases from 0.289 at 1000m to 0.256 at 200m and 0.215 at 100m below SAL top. We compare the modelled backscatter coefficients and linear depolarization ratios to ground-based lidar measurements performed during the SALTRACE field campaign in Barbados (Caribbean) and find agreement within the estimated uncertainties. We discuss the uncertainties of our modeling approach in our presentation. Assumed mineral dust particle shapes, assumed particle mixture properties, and assumptions about processes in the SAL over the continent and the ocean are important aspects to be considered. Uncertainties are relevant for the potential of lidar measurements of transported Saharan dust to learn something about processes occuring in the SAL during long-range transport. We also compare our modeling results to modeling results previously published in the literature.

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

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

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

  15. 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.

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

    NASA Technical Reports Server (NTRS)

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

    2002-01-01

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

  18. Dust layer profiling using an aerosol dropsonde

    NASA Astrophysics Data System (ADS)

    Ulanowski, Zbigniew; Kaye, Paul Henry; Hirst, Edwin; Wieser, Andreas; Stanley, Warren

    2015-04-01

    Routine meteorological data is obtained in the atmosphere using disposable radiosondes, giving temperature, pressure, humidity and wind speed. Additional measurements are obtained from dropsondes, released from research aircraft. However, a crucial property not yet measured is the size and concentration of atmospheric particulates, including dust. Instead, indirect measurements are employed, relying on remote sensing, to meet the demands from areas such as climate research, air quality monitoring, civil emergencies etc. In addition, research aircraft can be used in situ, but airborne measurements are expensive, and aircraft use is restricted to near-horizontal profiling, which can be a limitation, as phenomena such as long-range transport depend on the vertical distribution of aerosol. The Centre for Atmospheric and Instrumentation Research at University of Hertfordshire develops light-scattering instruments for the characterization of aerosols and cloud particles. Recently a range of low-cost, miniature particle counters has been created, intended for use with systems such as disposable balloon-borne radiosondes, dropsondes, or in dense ground-based sensor networks. Versions for different particle size ranges exist. They have been used for vertical profiling of aerosols such as mineral dust or volcanic ash. A disadvantage of optical particle counters that sample through a narrow inlet is that they can become blocked, which can happen in cloud, for example. Hence, a different counter version has been developed, which can have open-path geometry, as the sensing zone is defined optically rather than being delimited by the flow system. This counter has been used for ground based air-quality monitoring around Heathrow airport. The counter has also been adapted for use with radiosondes or dropsondes. The dropsonde version has been successfully tested by launching it from research aircraft together with the so-called KITsonde, developed at the Karlsruhe Institute of

  19. Radar frequency effect on the relationship between surface soil moisture vertical profile and radar backscatter

    NASA Astrophysics Data System (ADS)

    Zribi, Mehrez; Gorrab, Azza; Baghdadi, Nicolas; Lili-Chabaane, Zohra; Mougenot, Bernard; Boulet, Gilles

    2013-04-01

    Soil moisture plays a key role in hydrological and climatic studies. Considerable efforts have been devoted to the study of radar backscattering responses from natural surfaces in active microwave remote sensing. Electromagnetic analytical backscattering models (Kirchhoff models, the small perturbation method, and more recently the Integral Equation Model (IEM,the AIEM, …) have been used to estimate moisture parameter. However, various experimental measurements have shown that their use must be restricted to specific conditions. For studies in the L, C, and X frequency bands, empirical and semi-empirical models are often calibrated using soil samples collected down to a depth of five centimetres, in which the moisture content is assumed to be homogeneous. In recent years, some studies have revealed that using the actual, inhomogeneous soil moisture profile can make a significant difference in the results obtained from backscatter models. The aim of this paper is to discuss the influence of radar frequency on the relationship between surface soil moisture and the nature of radar backscatter over bare soils. In an attempt to answer this question, the Advanced Integral Equation Model (AIEM) was used to simulate backscatter from soil surfaces with various moisture vertical profiles, for three frequency bands: L, C and X. In these computations, we investigated the influence of the vertical heterogeneity of soil moisture on the characteristics of the backscattered signals. The influence of radar frequency is clearly demonstrated. A database produced from Envisat ASAR and TerraSAR-X data, acquired over bare soils with in situ measurements of moisture content and ground surface roughness, was used to validate the usefulness of taking the soil moisture heterogeneity into account in the backscattering model. These results confirm the significant influence of soil moisture heterogeneities on the strength of radar backscatter. It also highlights the sensitivity of inversion

  20. 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.

  1. Simulation of positron backscattering and implantation profiles using Geant4 code

    NASA Astrophysics Data System (ADS)

    Huang, Shi-Juan; Pan, Zi-Wen; Liu, Jian-Dang; Han, Rong-Dian; Ye, Bang-Jiao

    2015-10-01

    For the proper interpretation of the experimental data produced in slow positron beam technique, the positron implantation properties are studied carefully using the latest Geant4 code. The simulated backscattering coefficients, the implantation profiles, and the median implantation depths for mono-energetic positrons with energy range from 1 keV to 50 keV normally incident on different crystals are reported. Compared with the previous experimental results, our simulation backscattering coefficients are in reasonable agreement, and we think that the accuracy may be related to the structures of the host materials in the Geant4 code. Based on the reasonable simulated backscattering coefficients, the adjustable parameters of the implantation profiles which are dependent on materials and implantation energies are obtained. The most important point is that we calculate the positron backscattering coefficients and median implantation depths in amorphous polymers for the first time and our simulations are in fairly good agreement with the previous experimental results. Project supported by the National Natural Science Foundation of China (Grant Nos. 11175171 and 11105139).

  2. 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. PMID:25937543

  3. 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.

  4. Systematic observations of long-range transport events and climatological backscatter profiles with the DWD ceilometer network

    NASA Astrophysics Data System (ADS)

    Mattis, Ina; Müller, Gerhard; Wagner, Frank; Hervo, Maxime

    2015-04-01

    about 6 days per station, the optical depth of the dust particles was estimated to be larger than 0.4. Those events are classified as 'strong'. 'Faint', 'weak', and 'medium' events were detected at 13, 15, and 12 days per station, respectively. Almost all of the forest fire events have been classified as 'faint' and 'weak' with optical depths below 0.15. Beside this qualitative investigations on transport events, we started to obtain calibration constants for all individual ceilometers in our network within the framework of the European projects E-PROFILE and TOPROF. We are currently producing a data set of 1-hour-mean particle backscatter profiles at 1064 nm at all ceilometer stations in Germany for the period between summer 2013 and winter 2014. We will present an overview on the used methodologies of analysis of long-range transport events and of the calibration procedures. More detailed results of the event analysis, e.g. on seasonal behaviour will be presented as well. Further we will show results of a first statistical analysis of our 18-months data set of backscatter profiles over Germany.

  5. 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.

  6. Characterization of Florida red tide aerosol and the temporal profile of aerosol concentration

    PubMed Central

    Cheng, Yung Sung; Zhou, Yue; Pierce, Richard H.; Henry, Mike; Baden, Daniel G.

    2009-01-01

    Red tide aerosols containing aerosolized brevetoxins are produced during the red tide bloom and transported by wind to coastal areas of Florida. This study reports the characterization of Florida red tide aerosols in human volunteer studies, in which an asthma cohort spent 1 h on Siesta Beach (Sarasota, Florida) during aerosolized red tide events and non-exposure periods. Aerosol concentrations, brevetoxin levels, and particle size distribution were measured. Hourly filter samples were taken and analyzed for brevetoxin and NaCl concentrations. In addition, the aerosol mass concentration was monitored in real time. The results indicated that during a non-exposure period in October 2004, no brevetoxin was detected in the water, resulting in non-detectable levels of brevetoxin in the aerosol. In March 2005, the time-averaged concentrations of brevetoxins in water samples were moderate, in the range of 5–10 μg/L, and the corresponding brevetoxin level of Florida red tide aerosol ranged between 21 and 39 ng/m3. The temporal profiles of red tide aerosol concentration in terms of mass, NaCl, and brevetoxin were in good agreement, indicating that NaCl and brevetoxins are components of the red tide aerosol. By continuously monitoring the marine aerosol and wind direction at Siesta Beach, we observed that the marine aerosol concentration varied as the wind direction changed. The temporal profile of the Florida red tide aerosol during a sampling period could be explained generally with the variation of wind direction. PMID:19879288

  7. 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.

  8. Aerosol Profile Retrievals from Integrated Dual Wavelengths Space Lidar ESSP3-CENA and Spectral Radiance MODIS Data

    NASA Technical Reports Server (NTRS)

    Kaufman, Yoram; Mattoo, Shana; Tanre, Didier; Kleidman, Richard; Lau, William K. M. (Technical Monitor)

    2001-01-01

    The ESSP3-CENA space mission (formally PICASSO-CENA) will provide continues global observations with a two wavelength lidar. The attenuated backscattering coefficients measured by the lidar, have valuable information about the vertical distribution of aerosol particles and their sizes. However the information cannot be mapped into unique aerosol physical properties. Infinite number of physical solutions with different attenuations through the atmosphere can reconstruct the same two wavelength backscattered profile measured from space. Spectral radiance measured by MODIS simultaneously with the ESSP3 data can constrain the problem and resolve this ambiguity to a large extent. Sensitivity study shows that inversion of the integrated MODIS+ESSP3 data can derive the vertical profiles of the fine and coarse modes mixed in the same atmospheric column in the presence of moderate calibration uncertainties and electronic noise (approx. 10%). We shall present the sensitivity study and results from application of the technique to measurements in the SAFARI-2000 and SHADE experiments.

  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. Statistical Inversion of Acoustic Backscatter Profile Data with Sediment-Induced Attenuation

    NASA Astrophysics Data System (ADS)

    Wilson, G.; Hay, A. E.

    2014-12-01

    Multi-frequency acoustic backscatter inversion is a proven technique for measuring profiles of suspended sediment size and concentration. However, current inversion techniques tend to become inaccurate when sediment-induced acoustic attenuation is high (e.g., large suspended concentrations). In such cases, statistical fluctuations cause an accumulation of errors along the observed profile, which leads to an ill-posed inverse problem, even if the intrinsic properties of the scatterers are exactly known. Here, a statistical inversion methodology is introduced in which the ill-posed problem is regularized by explicitly considering the uncertainty of the observational data. The method uses the Extended Kalman Filter to estimate the propagation of uncertainty through the profile, followed by a variational smoothing step. This approach is shown to successfully estimate concentration and size profiles in cases where direct inversion fails. The method is also applied to laboratory experiments involving a multi-frequency megahertz acoustic profiler (MFDop) measuring a sediment-laden jet.

  11. 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

  12. Comparison of MADE3-simulated and observed aerosol distributions with a focus on aerosol vertical profiles

    NASA Astrophysics Data System (ADS)

    Kaiser, Christopher; Hendricks, Johannes; Righi, Mattia; Jöckel, Patrick

    2016-04-01

    The reliability of aerosol radiative forcing estimates from climate models depends on the accuracy of simulated global aerosol distribution and composition, as well as on the models' representation of the aerosol-cloud and aerosol-radiation interactions. To help improve on previous modeling studies, we recently developed the new aerosol microphysics submodel MADE3 that explicitly tracks particle mixing state in the Aitken, accumulation, and coarse mode size ranges. We implemented MADE3 into the global atmospheric chemistry general circulation model EMAC and evaluated it by comparison of simulated aerosol properties to observations. Compared properties include continental near-surface aerosol component concentrations and size distributions, continental and marine aerosol vertical profiles, and nearly global aerosol optical depth. Recent studies have shown the specific importance of aerosol vertical profiles for determination of the aerosol radiative forcing. Therefore, our focus here is on the evaluation of simulated vertical profiles. The observational data is taken from campaigns between 1990 and 2011 over the Pacific Ocean, over North and South America, and over Europe. The datasets include black carbon and total aerosol mass mixing ratios, as well as aerosol particle number concentrations. Compared to other models, EMAC with MADE3 yields good agreement with the observations - despite a general high bias of the simulated mass mixing ratio profiles. However, BC concentrations are generally overestimated by many models in the upper troposphere. With MADE3 in EMAC, we find better agreement of the simulated BC profiles with HIPPO data than the multi-model average of the models that took part in the AeroCom project. There is an interesting difference between the profiles from individual campaigns and more "climatological" datasets. For instance, compared to spatially and temporally localized campaigns, the model simulates a more continuous decline in both total

  13. Convective boundary layer evolution from lidar backscatter and its relationship with surface aerosol concentration at a location of a central China megacity

    NASA Astrophysics Data System (ADS)

    Kong, Wei; Yi, Fan

    2015-08-01

    Based on the 1 min backscatter ratio R profiles from the all-day lidar measurements in Wuhan, China (30.5°N, 114.4°E), hourly convective boundary layer (CBL) height was calculated with the variance method. The calculated CBL height sequence displays the regular diurnal cycle of the CBL top. The prevalent mixing process within the CBL is also revealed. During the CBL growth period, the backscatter ratio R falls visibly with increasing altitude and has large variance within the CBL, suggesting that more abundant aerosol particles from lower altitudes are being transported upward and being mixed with the local background or advected aerosol layers. During the CBL quasistationary period, R tends to be vertically uniform, and its variance reaches a daytime minimum within the CBL, indicating that the vertical homogenization of aerosol particles produced by the convectively driven mixing reaches its maximum. During the afternoon and early evening transition period, the vertical uniformity of R weakens and the variance enlarges again, implying that the reduced convectively driven mixing fails to maintain a high vertical homogeneity. When the 1 min R profiles were plotted together in terms of each 1 h interval, the fluctuating R curves at heights around the CBL top looked like a "node", representing the structure of the entrainment zone between the CBL and the free troposphere. The moving node depicts the evolution of the entrainment zone. The diurnal variation of the CBL height shows an obvious seasonal dependence which coincides with the annual variation of the local surface temperature. The surface fine particle concentration generally has a more complex diurnal cycle than that expected from the CBL-dilution/CBL-accumulation effect. But, it shows a strong annual variation which is out of phase with respect to that of the monthly mean maximum CBL height. This tends to suggest that the seasonal behavior of the surface fine particle concentration mainly depends on the

  14. 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.

  15. Development of ATLID-MSI synergy for retrieving the vertical profiles of aerosol components

    NASA Astrophysics Data System (ADS)

    Kudo, R.; Nishizawa, T.; Higurashi, A.; Sugimoto, N.; Oikawa, E.

    2014-12-01

    EarthCARE is an earth observation satellite and will be launched in 2016. Using its two sensors, ATLID (High spectral resolution lidar) and MSI (Multi-spectral imager), we are developing the synergy algorithm to retrieve the vertical profiles of extinction coefficients at 355 nm of four aerosol components (Water-soluble, black carbon, dust, and sea-salt particles), and the column mean of mode radii of water-soluble and dust particles. The ATLID data are extinction coefficient, backscatter coefficient, and depolarization ratio for total aerosols at 355 nm. The MSI data are radiances at 670 and 865 nm. The dry volume concentrations of four aerosol components at each altitude and the mode radii of water-soluble and dust particles in the column are simultaneously optimized to ATLID and MSI data by the gauss newton method. After the optimization, the vertical profiles of the extinction coefficient at 355 nm of four aerosol components are obtained. The size distributions of four aerosol components are assumed to be a lognormal distribution. The refractive indices of four aerosol components are given from previously observational studies. The humidity growth is considered for water-soluble and sea-salt particles. The volume concentration and the mode radius of the sea-salt particle are parameterized using the surface wind speed on the ocean. We assumed that the shape of the water-soluble, black carbon, and sea-salt particles are spherical, and the shape of the dust particle is spheroidal. We tested the algorithm using the ATLID and MSI data simulated using clean, dust-transported, and smoke-transported aerosols. The extinction coefficients of each component at 355 nm are retrieved well. The mode radius of water-soluble and dust particles were somehow overestimated.

  16. Measurements of aerosol properties needed to infer backscatter characteristics in support of the NASA Doppler Lidar program

    NASA Technical Reports Server (NTRS)

    Patterson, E. M.; Black, M. S.; Pollard, C. O.

    1989-01-01

    During the first year two areas of work were emphasized, analysis of aerosol data to provide improved estimates of backscatter over the Pacific ocean and development of a global model for backscatter at different wavelengths and preparation and planning for the aircraft flights of the GLOVE program. Significant progress was made in each of these areas. The analytical work is a continuation of the GAMETAG analysis, and was directed toward the development of a backscatter model for the Pacific Oceanic free troposphere. This has included a further evaluation of relationships between the optical effects at different wavelengths, a comparison of modeled optical effects at differing temporal resolutions, and an investigation of the effects of sampling on the modeled results. An initial investigation of the predictability of 9 to 10 micrometers Beta values from other data sets as well as some preliminary comparisons of the modeling results with experimental data. The comparison of the optical effects was extended to make the comparisons for different sets of time bases between 1 and 20 minutes.

  17. Quasi-analytical determination of noise-induced error limits in lidar retrieval of aerosol backscatter coefficient by the elastic, two-component algorithm.

    PubMed

    Sicard, Michaël; Comerón, Adolfo; Rocadenbosch, Francisco; Rodríguez, Alejandro; Muñoz, Constantino

    2009-01-10

    The elastic, two-component algorithm is the most common inversion method for retrieving the aerosol backscatter coefficient from ground- or space-based backscatter lidar systems. A quasi-analytical formulation of the statistical error associated to the aerosol backscatter coefficient caused by the use of real, noise-corrupted lidar signals in the two-component algorithm is presented. The error expression depends on the signal-to-noise ratio along the inversion path and takes into account "instantaneous" effects, the effect of the signal-to-noise ratio at the range where the aerosol backscatter coefficient is being computed, as well as "memory" effects, namely, both the effect of the signal-to-noise ratio in the cell where the inversion is started and the cumulative effect of the noise between that cell and the actual cell where the aerosol backscatter coefficient is evaluated. An example is shown to illustrate how the "instantaneous" effect is reduced when averaging the noise-contaminated signal over a number of cells around the range where the inversion is started. PMID:19137026

  18. Ceilometer for aerosol profiling: comparison with the multiwavelength in the frame of INTERACT (INTERcomparison of Aerosol and Cloud Tracking)

    NASA Astrophysics Data System (ADS)

    Madonna, Fabio; Vande Hey, Joshua; Rosoldi, Marco; Amato, Francesco; Pappalardo, Gelsomina

    2015-04-01

    project. This work is the first time that three different commercial ceilometers with an advanced Raman lidar are compared over a period of six months. The comparison of the attenuated backscatter profiles from a multi-wavelength Raman lidar and three ceilometers (CHM15k, CS135s, CT25K) reveals differences due to the expected discrepancy in the SNR but also due to effect of changes in the ambient temperature on the short and mid-term stability of ceilometer calibration. A large instability of ceilometers in the incomplete overlap region has also been observed, making the use of a single overlap correction function for the whole duration of the campaign critical. Therefore, technological improvements of ceilometers towards their operational use in the monitoring of the atmospheric aerosol in the low and free troposphere are needed.

  19. 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.

  20. 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.

  1. Aerosols and Precipitation Retrievals over Eureka by Remote Sensing: Validation of Space Based Profiling Retrievals

    NASA Astrophysics Data System (ADS)

    Chaubey, J. P.; O'Neill, N. T.; Hudak, D. R.; Rodriguez, P.; Ivanescu, L.; Eloranta, E.; Duck, T.

    2014-12-01

    Aerosols and precipitation are among the agents responsible for the ongoing changes in the Arctic climate and the hydrological cycle. The seasonal variations of Arctic aerosols (Arctic haze for e.g.) are linked to the transport efficiency as well as precipitation (wet) scavenging. Aside from affecting aerosol concentrations, precipitation is an important hydrological variable that affects the moisture budget of the atmosphere. Aerosols, in turn, influence the vertical distribution of clouds and this induces changes in the precipitation pattern. The spatial and temporal sparsity of precipitation measurements over the Arctic region means that satellite remote sensing techniques take on an importance that considerably exceeds their role south of the Arctic circle. Radar reflectivity and snow profiles from CloudSat (in support of cloud and precipitation analyses) and backscattering measurements from CALIOP (investigations of aerosol and small cloud particle properties) can be used to study Arctic winter clouds and precipitation and the role of aerosols in their formation. In this study we attempt to validate satellite-based profiling retrievals of precipitation parameters using AHSRL (Arctic High Spectral Resolution Lidar), CRL (CANDAC Raman Lidar) and MMCR (Milli-Meter Cloud Radar) profiles acquired at the PEARL high-Arctic site in Eureka (80 °N, 86 °W), Nunavut, Canada. As part of the process of validating the profiling retrievals we aspire to learn more about the mechanisms controlling aerosol, cloud and precipitation inter-dynamics. In addition, ground-based, high-frequency observations of precipitation will be used for characterizing precipitation totals as well as the conditional probability of the type of precipitation (rain or snow) and thus to help understand and validate comparable information extracted from the satellite retrievals. We also aim to characterize different particle types using AHSRL and CRL depolarization profiles, MMCR Doppler velocity

  2. Profiling Transboundary Aerosols over Taiwan and Assessing Their Radiative Effects

    NASA Technical Reports Server (NTRS)

    Wang, Sheng-Hsiang; Lin, Neng-Huei; Chou, Ming-Dah; Tsay, Si-Chee; Welton, Ellsworth J.; Hsu, N. Christina; Giles, David M.; Liu, Gin-Rong; Holben, Brent N.

    2010-01-01

    A synergistic process was developed to study the vertical distributions of aerosol optical properties and their effects on solar heating using data retrieved from ground-based radiation measurements and radiative transfer simulations. Continuous MPLNET and AERONET observations were made at a rural site in northern Taiwan from 2005 to 2007. The aerosol vertical extinction profiles retrieved from ground-based lidar measurements were categorized into near-surface, mixed, and two-layer transport types, representing 76% of all cases. Fine-mode (Angstrom exponent, alpha, approx.1.4) and moderate-absorbing aerosols (columnar single-scattering albedo approx.0.93, asymmetry factor approx.0.73 at 440 nm wavelength) dominated in this region. The column-integrated aerosol optical thickness at 500 nm (tau(sub 500nm)) ranges from 0.1 to 0.6 for the near-surface transport type, but can be doubled in the presence of upper-layer aerosol transport. We utilize aerosol radiative efficiency (ARE; the impact on solar radiation per unit change of tau(sub 500nm)) to quantify the radiative effects due to different vertical distributions of aerosols. Our results show that the ARE at the top-of-atmosphere (-23 W/ sq m) is weakly sensitive to aerosol vertical distributions confined in the lower troposphere. On the other hand, values of the ARE at the surface are -44.3, -40.6 and -39.7 W/sq m 38 for near-surface, mixed, and two-layer transport types, respectively. Further analyses show that the impact of aerosols on the vertical profile of solar heating is larger for the near-surface transport type than that of two-layer transport type. The impacts of aerosol on the surface radiation and the solar heating profiles have implications for the stability and convection in the lower troposphere.

  3. Research on aerosol profiles and parameterization scheme in Southeast China

    NASA Astrophysics Data System (ADS)

    Wang, Gang; Deng, Tao; Tan, Haobo; Liu, Xiantong; Yang, Honglong

    2016-09-01

    The vertical distribution of the aerosol extinction coefficient serves as a basis for evaluating aerosol radiative forcing and air quality modeling. In this study, MODIS AOD data and ground-based lidar extinction coefficients were employed to verify 6 years (2009-2014) aerosol extinction data obtained via CALIOP for Southeast China. The objective was mainly to provide the parameterization scheme of annual and seasonal aerosol extinction profiles. The results showed that the horizontal and vertical distributions of CALIOP extinction data were highly accurate in Southeast China. The annual average AOD below 2 km accounted for 64% of the total layer, with larger proportions observed in winter (80%) and autumn (80%) and lower proportions observed in summer (70%) and spring (59%). The AOD was maximum in the spring (0.58), followed by the autumn and winter (0.44), and reached a minimum in the summer (0.40). The near-surface extinction coefficient increased from summer, spring, autumn and winter, in that order. The Elterman profile is obviously lower than the profiles observed by CALIOP in Southeast China. The annual average and seasonal aerosol profiles showed an exponential distribution, and could be divided into two sections. Two sections exponential fitting was used in the parameterization scheme. In the first section, the aerosol scale height reached 2200 m with a maximum (3,500 m) in summer and a minimum (1,230 m) in winter, which meant that the aerosol extinction decrease with height slower in summer, but more rapidly in winter. In second section, the aerosol scale height was maximum in spring, which meant that the higher aerosol diffused in spring.

  4. Ceilometer Aerosol Profiling versus Raman Lidar in the Frame of Interact Campaign of Actris

    NASA Astrophysics Data System (ADS)

    Madonna, F.; Amato, F.; Rosoldi, M.; Vande Hey, J.; Pappalardo, G.

    2016-06-01

    In this paper, multi-wavelength Raman lidar measurements are used to investigate the capability of ceilometers to provide reliable information about atmospheric aerosol properties through the INTERACT (INTERcomparison of Aerosol and Cloud Tracking) campaign carried out at the CNR-IMAA Atmospheric Observatory (760 m a.s.l., 40.60 N, 15.72 E), in the framework of ACTRIS (Aerosol Clouds Trace gases Research InfraStructure) FP7 project. This work is the first time that three different commercial ceilometers with an advanced Raman lidar are compared over a period of six month. The comparison of the attenuated backscatter coefficient profiles from a multi-wavelength Raman lidar and three ceilometers (CHM15k, CS135s, CT25K) reveals differences due to the expected discrepancy in the SNR but also due to effect of changes in the ambient temperature on the stability of ceilometer calibration over short and mid-term. Technological improvements of ceilometers towards their operational use in the monitoring of the atmospheric aerosol in the low and free troposphere are likely needed.

  5. 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. PMID:19543338

  6. 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.

  7. Imaginary refractive-index effects on desert-aerosol extinction versus backscatter relationships at 351 nm: numerical computations and comparison with Raman lidar measurements.

    PubMed

    Perrone, Maria Rita; Barnaba, Francesca; De Tomasi, Ferdinando; Gobbi, Gian Paolo; Tafuro, Anna Maria

    2004-10-10

    A numerical model is used to investigate the dependence at 351 nm of desert-aerosol extinction and backscatter coefficients on particle imaginary refractive index (mi). Three ranges (-0.005 < or = mi < or = -0.001, -0.01 < or = mi < or = -0.001, and -0.02 < or = mi < or = -0.001) are considered, showing that backscatter coefficients are reduced as /mi/ increases, whereas extinction coefficients are weakly dependent on mi. Numerical results are compared with extinction and backscatter coefficients retrieved by elastic Raman lidar measurements performed during Saharan dust storms over the Mediterranean Sea. The comparison indicates that a range of -0.01 to -0.001 can be representative of Saharan dust aerosols and that the nonsphericity of mineral particles must be considered. PMID:15508611

  8. EARLINET: 12-year of Aerosol Profiling over Europe

    NASA Astrophysics Data System (ADS)

    Mona, L.; Alados Arboledas, L.; Amiridis, V.; Amodeo, A.; Apituley, A.; Balis, D.; Comeron, A.; Iarlori, M.; Linné, H.; Nicolae, D.; Papayannis, A.; Perrone, M. R.; Rizi, V.; Siomos, N.; Wandinger, U.; Wang, X.; Pappalardo, G.

    2016-06-01

    EARLINET has been collecting high quality aerosol optical profiles over Europe since 2000. The comparison with automatic collected dataset of aerosol optical depth (AOD) from AERONET and MODIS demonstrates the effectiveness of EARLINET regular measurement schedule for climatological studies. The analysis of optical properties in the local boundary layer indicates that the general decrease of AOD observed by different platforms over Europe in the last decade could be due to the modification of aerosol properties (towards less absorbing and larger particles) in the lower troposphere.

  9. Implementation of Rotational Raman Channel in Multiwavelength Aerosol Lidar to Improve Measurements of Particle Extinction and Backscattering at 532 NM

    NASA Astrophysics Data System (ADS)

    Veselovskii, Igor; Whiteman, David N.; Korenskiy, Michael; Suvorina, A.; Perez-Ramirez, Daniel

    2016-06-01

    We describe a practical implementation of rotational Raman (RR) measurements in an existing Mie-Raman lidar to obtain measurements of aerosol extinction and backscattering at 532 nm. A 2.3 nm width interference filter was used to select a spectral range characterized by low temperature sensitivity within the anti-Stokes branch of the RR spectrum. Simulations demonstrate that the temperature dependence of the scattering cross section does not exceed 1.0% in the 230-300K range making accurate correction for this dependence quite easy. With this upgrade, the NASA/GSFC multiwavelength Raman lidar has demonstrated useful α532 measurements and was used for regular observations. Examples of lidar measurements and inversion of optical data to the particle microphysics will be given in presentation.

  10. PollyNET: a global network of automated Raman-polarization lidars for continuous aerosol profiling

    NASA Astrophysics Data System (ADS)

    Baars, H.; Kanitz, T.; Engelmann, R.; Althausen, D.; Heese, B.; Komppula, M.; Preißler, J.; Tesche, M.; Ansmann, A.; Wandinger, U.; Lim, J.-H.; Ahn, J. Y.; Stachlewska, I. S.; Amiridis, V.; Marinou, E.; Seifert, P.; Hofer, J.; Skupin, A.; Schneider, F.; Bohlmann, S.; Foth, A.; Bley, S.; Pfüller, A.; Giannakaki, E.; Lihavainen, H.; Viisanen, Y.; Hooda, R. K.; Pereira, S.; Bortoli, D.; Wagner, F.; Mattis, I.; Janicka, L.; Markowicz, K. M.; Achtert, P.; Artaxo, P.; Pauliquevis, T.; Souza, R. A. F.; Sharma, V. P.; van Zyl, P. G.; Beukes, J. P.; Sun, J. Y.; Rohwer, E. G.; Deng, R.; Mamouri, R. E.; Zamorano, F.

    2015-10-01

    A global vertically resolved aerosol data set covering more than 10 years of observations at more than 20 measurement sites distributed from 63° N to 52° S and 72° W to 124° E has been achieved within the Raman and polarization lidar network PollyNET. This network consists of portable, remote-controlled multiwavelength-polarization-Raman lidars (Polly) for automated and continuous 24/7 observations of clouds and aerosols. PollyNET is an independent, voluntary, and scientific network. All Polly lidars feature a standardized instrument design and apply unified calibration, quality control, and data analysis. The observations are processed in near-real time without manual intervention, and are presented online at http://polly.tropos.de. The paper gives an overview of the observations on four continents and two research vessels obtained with eight Polly systems. The specific aerosol types at these locations (mineral dust, smoke, dust-smoke and other dusty mixtures, urban haze, and volcanic ash) are identified by their Ångström exponent, lidar ratio, and depolarization ratio. The vertical aerosol distribution at the PollyNET locations is discussed on the basis of more than 55 000 automatically retrieved 30 min particle backscatter coefficient profiles at 532 nm. A seasonal analysis of measurements at selected sites revealed typical and extraordinary aerosol conditions as well as seasonal differences. These studies show the potential of PollyNET to support the establishment of a global aerosol climatology that covers the entire troposphere.

  11. Lidar profiling of aerosol optical properties from Paris to Lake Baikal (Siberia)

    NASA Astrophysics Data System (ADS)

    Dieudonné, E.; Chazette, P.; Marnas, F.; Totems, J.; Shang, X.

    2015-05-01

    In June 2013, a ground-based mobile lidar performed the ~10 000 km ride from Paris to Ulan-Ude, near Lake Baikal, profiling for the first time aerosol optical properties all the way from western Europe to central Siberia. The instrument was equipped with N2-Raman and depolarization channels that enabled an optical speciation of aerosols in the low and middle troposphere. The extinction-to-backscatter ratio (also called lidar ratio or LR) and particle depolarization ratio (PDR) at 355 nm have been retrieved. The LR in the lower boundary layer (300-700 m) was found to be 63 ± 17 sr on average during the campaign with a distribution slightly skewed toward higher values that peaks between 50 and 55 sr. Although the difference is small, PDR values observed in Russian cities (>2%, except after rain) are systematically higher than the ones measured in Europe (<1%), which is probably an effect of the lifting of terrigenous aerosols by traffic on roads. Biomass burning layers from grassland or/and forest fires in southern Russia exhibit LR values ranging from 65 to 107 sr and from 3 to 4% for the PDR. During the route, desert dust aerosols originating from the Caspian and Aral seas regions were characterized for the first time, with a LR (PDR) of 43 ± 14 sr (23 ± 2%) for pure dust. The lidar observations also showed that this dust event extended over 2300 km and lasted for ~6 days. Measurements from the Moderate Resolution Imaging Spectrometer (MODIS) show that our results are comparable in terms of aerosol optical thickness (between 0.05 and 0.40 at 355 nm) with the mean aerosol load encountered throughout our route.

  12. Lidar profiling of aerosol optical properties from Paris to Lake Baikal (Siberia)

    NASA Astrophysics Data System (ADS)

    Dieudonné, E.; Chazette, P.; Marnas, F.; Totems, J.; Shang, X.

    2014-11-01

    In June 2013, a ground-based mobile lidar performed the 10 000 km ride from Paris to Ulan-Ude, near Lake Baikal, profiling for the first time aerosol optical properties all the way from Western Europe to central Siberia. The instrument was equipped with N2-Raman and depolarization channels that enabled an optical speciation of aerosols in the low and middle troposphere. The backscatter-to-extinction ratio (BER) and particle depolarization ratio (PDR) at 355 nm have been retrieved. The BER in the lower boundary layer (300-700 m) was found to be 0.017 ± 0.009 sr-1 in average during the campaign, with slightly higher values in background conditions near Lake Baikal (0.021 ± 0.010 sr-1 in average) corresponding to dust-like particles. PDR values observed in Russian cities (>1.7%) are higher than the ones measured in European cities (<1.3%) due to the lifting of terrigenous aerosols by traffic on roads with a bad tarmac. Biomass burning layers from grassland or/and forest fires in southern Russia exhibit BER values ranging from 0.010 to 0.015 sr-1 and from 2 to 3% for the PDR. Desert dust aerosols originating from the Caspian and Aral seas regions were characterized for the first time, with a BER (PDR) of 0.022 sr-1 (21%) for pure dust, and 0.011 sr-1 (15%) for a mix between dust and biomass burning. The lidar observations also showed that this dust event extended over 2300 km and lasted for ~6 days. Measurements from the Moderate Resolution Imaging Spectrometer (MODIS) show that our results are comparable in terms of aerosol optical thickness (between 0.05 and 0.40 at 355 nm) with the mean aerosol load encountered throughout our route.

  13. Ceilometer aerosol profiling versus Raman lidar in the frame of the INTERACT campaign of ACTRIS

    NASA Astrophysics Data System (ADS)

    Madonna, F.; Amato, F.; Vande Hey, J.; Pappalardo, G.

    2015-05-01

    Despite their differences from more advanced and more powerful lidars, the low construction and operation cost of ceilometers (originally designed for cloud base height monitoring) has fostered their use for the quantitative study of aerosol properties. The large number of ceilometers available worldwide represents a strong motivation to investigate both the extent to which they can be used to fill in the geographical gaps between advanced lidar stations and also how their continuous data flow can be linked to existing networks of the more advanced lidars, like EARLINET (European Aerosol Research Lidar Network). In this paper, multi-wavelength Raman lidar measurements are used to investigate the capability of ceilometers to provide reliable information about atmospheric aerosol properties through the INTERACT (INTERcomparison of Aerosol and Cloud Tracking) campaign carried out at the CNR-IMAA Atmospheric Observatory (760 m a.s.l., 40.60° N, 15.72° E), in the framework of the ACTRIS (Aerosol Clouds Trace gases Research InfraStructure) FP7 project. This work is the first time that three different commercial ceilometers with an advanced Raman lidar are compared over a period of 6 months. The comparison of the attenuated backscatter coefficient profiles from a multi-wavelength Raman lidar and three ceilometers (CHM15k, CS135s, CT25K) reveals differences due to the expected discrepancy in the signal to noise ratio (SNR) but also due to changes in the ambient temperature on the short and mid-term stability of ceilometer calibration. Therefore, technological improvements are needed to move ceilometers towards operational use in the monitoring of atmospheric aerosols in the low and free troposphere.

  14. Ceilometer aerosol profiling vs. Raman lidar in the frame of INTERACT campaign of ACTRIS

    NASA Astrophysics Data System (ADS)

    Madonna, F.; Amato, F.; Vande Hey, J.; Pappalardo, G.

    2014-12-01

    Despite their differences from more advanced and more powerful lidars, the low construction and operation cost of ceilometers, originally designed for cloud base height monitoring, has fostered their use for the quantitative study of aerosol properties. The large number of ceilometers available worldwide represents a strong motivation to investigate both the extent to which they can be used to fill in the geographical gaps between advanced lidar stations and also how their continuous data flow can be linked to existing networks of the more advanced lidars, like EARLINET (European Aerosol Research LIdar NETwork). In this paper, multi-wavelength Raman lidar measurements are used to investigate the capability of ceilometers to provide reliable information about atmospheric aerosol content through the INTERACT (INTERcomparison of Aerosol and Cloud Tracking) campaign carried out at the CNR-IMAA Atmospheric Observatory (760 m a.s.l., 40.60° N, 15.72° E), in the framework of ACTRIS (Aerosol Clouds Trace gases Research InfraStructure) FP7 project. This work is the first time that three different commercial ceilometers with an advanced Raman lidar are compared over a period of six months. The comparison of the attenuated backscatter profiles from a multi-wavelength Raman lidar and three ceilometers (CHM15k, CS135s, CT25K) reveals differences due to the expected discrepancy in the SNR but also due to effect of changes in the ambient temperature on the short and mid-term stability of ceilometer calibration. A large instability of ceilometers in the incomplete overlap region has also been observed, making the use of a single overlap correction function for the whole duration of the campaign critical. Therefore, technological improvements of ceilometers towards their operational use in the monitoring of the atmospheric aerosol in the low and free troposphere are needed.

  15. Aerosol and cloud backscatter at 1.06, 1.54, and 0.53 mum by airborne hard-target-calibrated Nd:YAG /methane Raman lidar.

    PubMed

    Spinhirne, J D; Chudamani, S; Cavanaugh, J F; Bufton, J L

    1997-05-20

    A lidar instrument was developed to make simultaneous measurements at three distinct wavelengths in the visible and near infrared at 0.532, 1.064, and 1.54 mum with high cross-sectional calibration accuracy. Aerosol and cloud backscatter cross sections were acquired during November and December 1989 and May and June 1990 by the NASA DC-8 aircraft as part of the Global Backscatter Experiment. The instrument, methodology, and measurement results are described. A Nd:YAG laser produced 1.064- and 0.532-mum energy. The 1.54-mum transmitted pulse was generated by Raman-shifted downconversion of the 1.064-mum pulse through a Raman cell pressured with methane gas. The lidar could be pointed in the nadir or zenith direction from the aircraft. A hard-target-based calibration procedure was used to obtain the ratio of the system calibration between the three wavelengths, and the absolute calibration was referenced to the 0.532-mum lidar molecular backscatter cross section for the clearest scattering regions. From the relative wavelength calibration, the aerosol backscatter cross sections at the longer wavelengths are resolved for values as small as 1% of the molecular cross section. Backscatter measurement accuracies are better than 10(-9) (m sr)(-1) at 1.064 and 1.54 mum. Results from the Pacific Ocean region of the multiwavelength backscatter dependence are presented. Results show extensive structure and variation for the aerosol cross sections. The range of observed aerosol cross section is over 4 orders of magnitude, from less than 10(-9) (m sr)(-1) to greater than 10(-5) (m sr)(-1). PMID:18253366

  16. Aerosol effect on Umkehr ozone profiles using Stratospheric Aerosol and Gas Experiment II measurements

    NASA Technical Reports Server (NTRS)

    Newchurch, M. J.; Cunnold, D. M.

    1994-01-01

    This study examines 1211 cases of coincident ozone profiles derived from 1164 Umkehrs and 928 Stratospheric Aerosol and Gas Experiment II (SAGE II) profiles within 1000 km and 12 hours between October 1984 and April 1989 to study the stratospheric-aerosol effect on Umkehr ozone profiles. Because of the close correspondence of stratospheric aerosol optical depth at the SAGE II-measured 0.525-micrometer wavelength and the extrapolated 0.32 Umkehr wavelength determined in this study we use the 0.525-micrometer data to determine the aerosol effect on Umkehr profiles. At the 95% confidence level, we find the following errors to the Umkehr ozone amounts: in Umkehr layer 9 (-2.9 +/- 2.1), layer 8 (-2.3 +/- 1.1), layer 7 (0.1 +/- 1.1), layer 6 (2.2 +/- 1.0), layer 5 (-1.5 +/- 0.8), and layer 4 (-2.4 +/- 1.7) in percent ozone amount per 0.01 stratospheric aerosol optical depth. These results agree with previous theoretical and empirical studies within their respective error bounds in layers 9, 8, and 7. The results in layers 6, 5, and 4 differ significantly from those in previous works. Using only those eight stations with more than 47 coincidences results in mean aerosol effects that are not significantly different from the 14-station results. Because SAGE II and Umkehr produce different ozone retrievals in layer 9 and because the intralayer correlation of SAGE II ozone and aerosol in layer 9 is nonzero, one must exercise some caution in attributing the entire SAGE II-Umkehr difference in this layer to an aerosol effect.

  17. Global Aerosol Profiling by Orbital Lidar, GLAS Results and Validation

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

    The Geoscience Laser Altimeter System (GLAS) launched in 2003 is the first polar orbiting satellite lidar. The instrument was designed for high performance observations of the distribution and optical scattering cross sections of clouds and aerosol. GLAS is approaching six months of on orbit data operation. These data from thousands of orbits illustrate the ability of space lidar to accurately and dramatically measure the height distribution of global aerosol to an unprecedented degree. There were many intended science applications of the GLAS data and significant results have already been realized, profiling is a fundamentally new measurement from space with multiple applications. A most important aerosol application is providing input to global aerosol generation transport models. Another is improved measurement of aerosol optical depth. A main approach to verify the aerosol optical depth retrieval is comparison to surface measurements by Aeronet. A special feature of the GLAS satellite bus is to rapidly point the lidar instrument at off nadir targets with less than 100 m accuracy. About a dozen selected Aeronet sites were pointed at whenever the GLAS lidar came within 5 degrees of zenith. These plus a more general comparison to nearby sites support the GLAS data product values. In addition the GLAS data can be used to add vertical distribution information to Aeronet aerosol measurements. As an EOS project instrument, GLAS data products are openly available to the science community. First year results from GLAS are summarized.

  18. Global Aerosol Profiling by Orbital Lidar, GLAS Results and Validation

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

    The Geoscience Laser Altimeter System (GLAS) launched in 2003 is the first polar orbiting satellite lidar. The instrument was designed for high performance observations of the distribution and optical scattering cross sections of clouds and aerosol. GLAS is approaching six months of on orbit data operation. These data from thousands of orbits illustrate the ability of space lidar to accurately and dramatically measure the height distribution of global aerosol to an unprecedented degree. There were many intended science applications of the GLAS data and significant results have already been realized. profiling is a fundamentally new measurement from space with multiple applications. A most important aerosol application is providing input to global aerosol generation and transport models. Another is improved measurement of aerosol optical depth. A main approach to verify the aerosol optical depth retrieval is comparison to surface measurements by Aeronet. A special feature of the GLAS satellite bus is to rapidly point the lidar instrument at off nadir targets with less than 100 m accuracy. About a dozen selected Aeronet sites were pointed at whenever the G U S lidar came within 5 degrees of zenith. These plus a more general comparison to nearby sites support the G U S data product values. In addition the GUS data can be used to add vertical distribution information to Aeronet aerosol measurements.. As an EOS project instrument, GLAS data products are openly available to the science community. First year results from G U S are summarized.

  19. Photothermal depth profiling: Comparison between genetic algorithms and thermal wave backscattering (abstract)

    NASA Astrophysics Data System (ADS)

    Li Voti, R.; Sibilia, C.; Bertolotti, M.

    2003-01-01

    Photothermal depth profiling has been the subject of many papers in the last years. Inverse problems on different kinds of materials have been identified, classified, and solved. A first classification has been done according to the type of depth profile: the physical quantity to be reconstructed is the optical absorption in the problems of type I, the thermal effusivity for type II, and both of them for type III. Another classification may be done depending on the time scale of the pump beam heating (frequency scan, time scan), or on its geometrical symmetry (one- or three-dimensional). In this work we want to discuss two different approaches, the genetic algorithms (GA) [R. Li Voti, C. Melchiorri, C. Sibilia, and M. Bertolotti, Anal. Sci. 17, 410 (2001); R. Li Voti, Proceedings, IV Int. Workshop on Advances in Signal Processing for Non-Destructive Evaluation of Materials, Quebec, August 2001] and the thermal wave backscattering (TWBS) [R. Li Voti, G. L. Liakhou, S. Paoloni, C. Sibilia, and M. Bertolotti, Anal. Sci. 17, 414 (2001); J. C. Krapez and R. Li Voti, Anal. Sci. 17, 417 (2001)], showing their performances and limits of validity for several kinds of photothermal depth profiling problems: The two approaches are based on different mechanisms and exhibit obviously different features. GA may be implemented on the exact heat diffusion equation as follows: one chromosome is associated to each profile. The genetic evolution of the chromosome allows one to find better and better profiles, eventually converging towards the solution of the inverse problem. The main advantage is that GA may be applied to any arbitrary profile, but several disadvantages exist; for example, the complexity of the algorithm, the slow convergence, and consequently the computer time consumed. On the contrary, TWBS uses a simplified theoretical model of heat diffusion in inhomogeneous materials. According to such a model, the photothermal signal depends linearly on the thermal effusivity

  20. The Backscatter Cloud Probe - a compact low-profile autonomous optical spectrometer

    NASA Astrophysics Data System (ADS)

    Beswick, K.; Baumgardner, D.; Gallagher, M.; Newton, R.

    2013-08-01

    A compact (500 cm3), lightweight (500 g), near-field, single particle backscattering optical spectrometer is described that mounts flush with the skin of an aircraft and measures the concentration and optical equivalent diameter of particles from 5 to 75 μm. The Backscatter Cloud Probe (BCP) was designed as a real-time qualitative cloud detector primarily for data quality control of trace gas instruments developed for the climate monitoring instrument packages that are being installed on commercial passenger aircraft as part of the European Union In-Service Aircraft for a Global Observing System (IAGOS) program (http://www.iagos.org/). Subsequent evaluations of the BCP measurements on a number of research aircraft, however, have revealed it capable of delivering quantitative particle data products including size distributions, liquid water content and other information on cloud properties. We demonstrate the instrument's capability for delivering useful long-term climatological information, across a wide range of environmental conditions. The BCP has been evaluated by comparing its measurements with those from other cloud particle spectrometers on research aircraft and several BCPs are currently flying on commercial A340/A330 Airbus passenger airliners. The design and calibration of the BCP is described in this presentation, along with an evaluation of measurements made on the research and commercial aircraft. Comparisons of the BCP with two other cloud spectrometers, the Cloud Droplet Probe (CDP) and the Cloud and Aerosol Spectrometer (CAS), show that the BCP size distributions agree well with those from the other two, given the intrinsic limitations and uncertainties related to the three instruments. Preliminary results from more than 7000 h of airborne measurements by the BCP on two Airbus A-340s operating on routine global traffic routes (one Lufthansa, the other China Airlines) show that more than 340 h of

  1. Modeling of Aerosol Vertical Profiles Using GIS and Remote Sensing

    PubMed Central

    Wong, Man Sing; Nichol, Janet E.; Lee, Kwon Ho

    2009-01-01

    The use of Geographic Information Systems (GIS) and Remote Sensing (RS) by climatologists, environmentalists and urban planners for three dimensional modeling and visualization of the landscape is well established. However no previous study has implemented these techniques for 3D modeling of atmospheric aerosols because air quality data is traditionally measured at ground points, or from satellite images, with no vertical dimension. This study presents a prototype for modeling and visualizing aerosol vertical profiles over a 3D urban landscape in Hong Kong. The method uses a newly developed technique for the derivation of aerosol vertical profiles from AERONET sunphotometer measurements and surface visibility data, and links these to a 3D urban model. This permits automated modeling and visualization of aerosol concentrations at different atmospheric levels over the urban landscape in near-real time. Since the GIS platform permits presentation of the aerosol vertical distribution in 3D, it can be related to the built environment of the city. Examples are given of the applications of the model, including diagnosis of the relative contribution of vehicle emissions to pollution levels in the city, based on increased near-surface concentrations around weekday rush-hour times. The ability to model changes in air quality and visibility from ground level to the top of tall buildings is also demonstrated, and this has implications for energy use and environmental policies for the tall mega-cities of the future. PMID:22408531

  2. Tropospheric Vertical Profiles of Aerosol Optical, Microphysical and Concentration Properties in the Frame of the Hygra-CD Campaign (Athens, Greece 2014): A Case Study of Long-Range Transport of Mixed Aerosols

    NASA Astrophysics Data System (ADS)

    Papayannis, Alexandros; Argyrouli, Athina; Müller, Detlef; Tsaknakis, Georgios; Kokkalis, Panayotis; Binietoglou, Ioannis; Kazadzis, Stelios; Solomos, Stavros; Amiridis, Vassilis

    2016-06-01

    Combined multi-wavelength aerosol Raman lidar and sun photometry measurements were performed during the HYGRA-CD campaign over Athens, Greece during May-June 2014. The retrieved aerosol optical properties (3 aerosol backscatter at 355-532-1064 nm and 2 aerosol extinction profiles at 355-532 nm) were used as input to an inversion code to retrieve the aerosol microphysical properties (effective radius reff and number concentration N) using regularization techniques. Additionally, the volume concentration profile was derived for fine particles using the LIRIC code. In this paper we selected a complex case study of long-range transport of mixed aerosols (biomass burning particles mixed with dust) arriving over Athens between 10-12 June 2014 in the 1.5-4 km height. Between 2-3 km height we measured mean lidar ratios (LR) ranging from 45 to 58 sr (at 355 and 532 nm), while the Ångström exponent (AE) aerosol extinction-related values (355nm/532nm) ranged between 0.8-1.3. The retrieved values of reff and N ranged from 0.19±0.07 to 0.22±0.07 μm and 460±230 to 2200±2800 cm-3, respectively. The aerosol linear depolarization ratio (δ) at 532 nm was lower than 5-7% (except for the Saharan dust cases, where δ~10-15%).

  3. Global profiles of the direct aerosol effect using vertically resolved aerosol data

    NASA Astrophysics Data System (ADS)

    Korras Carraca, Marios Bruno; Pappas, Vasilios; Matsoukas, Christos; Hatzianastassiou, Nikolaos; Vardavas, Ilias

    2014-05-01

    Atmospheric aerosols, both natural and anthropogenic, can cause climate change through their direct, indirect, and semi-direct effects on the radiative energy budget of the Earth-atmosphere system. In general, aerosols cause cooling of the surface and the planet, while they warm the atmosphere due to scattering and absorption of incoming solar radiation. The importance of vertically resolved direct radiative effect (DRE) and heating/cooling effects of aerosols is strong, while large uncertainties still lie with their magnitudes. In order to be able to quantify them throughout the atmosphere, a detailed vertical profile of the aerosol effect is required. Such data were made available recently by the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) on board the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite. CALIOP is the first polarization lidar to fly in space and has been acquiring unique data on aerosols and clouds since June 2006. The aim of this study is to investigate both the vertically resolved geographic and seasonal variation of the DRE due to aerosols. The vertical profile of DRE under all-sky and clear-sky conditions is computed using the deterministic spectral radiative transfer model FORTH. From the DRE, the effect on atmospheric heating/cooling rate profiles due to aerosols can also be derived. We use CALIOP Level 2-Version 3 Layer aerosol optical depth data as input to our radiation transfer model, for a period of 3 complete years (2007-2009). These data are provided on a 5 km horizontal resolution and in up to 8 vertical layers and have been regridded on our model horizontal and vertical resolutions. We use cloud data from the International Satellite Cloud Climatology Project (ISCCP), while the aerosol asymmetry factor and single scattering albedo are taken from the Global Aerosol Data Set (GADS). The model computations are performed on a monthly, 2.5°× 2.5° resolution on global scale, at 40

  4. 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

  5. ACTRIS aerosol vertical profile data and observations: potentiality and first examples of integrated studies with models

    NASA Astrophysics Data System (ADS)

    Mona, Lucia; Benedetti, Angela; D'Amico, Giuseppe; Myhre, Cathrine Lund; Schulz, Michael; Wandinger, Ulla; Laj, Paolo; Pappalardo, Gelsomina

    2016-04-01

    The ACTRIS-2 project, funded by Horizon 2020, addresses the scope of integrating state-of-the-art European ground-based stations for long term observations of aerosols, clouds and short lived gases, capitalizing on the work of FP7-ACTRIS. It aims at achieving the construction of a user-oriented RI, unique in the EU-RI landscape for providing 4-D integrated high-quality data from near-surface to high altitude (vertical profiles and total-column) which are relevant to climate and air-quality research. ACTRIS-2 develops and implements, in a large network of stations in Europe and beyond, observational protocols that permit the harmonization of collected data and their dissemination. ACTRIS secures provision and dissemination of a unique set of data and data-products that would not otherwise be available with the same level of quality and standardization. This results from a 10-year plus effort in constructing a research infrastructure capable of responding to community needs and requirements, and has been engaged since the start of the FP5 EU commission program. ACTRIS ensures compliance with reporting requirements (timing, format, traceability) defined by the major global observing networks. EARLINET (European Aerosol research Lidar NETwork), the aerosol vertical profiling component of ACTRIS, is providing since May 2000 vertical profiles of aerosol extinction and backscatter over Europe. A new structure of the EARLINET database has been designed in a more user oriented approach reporting new data products which are more effective for specific uses of different communities. In particular, a new era is starting with the Copernicus program during which the aerosol vertical profiling capability will be fundamental for assimilation and validation purposes. The new data products have been designed thanks to a strong link with EARLINET data users, first of all modeling and satellite communities, established since the beginning of EARLINET and re-enforced within ACTRIS2

  6. Acoustic Attenuation and Backscatter Properties of a River Water Column Derived from Laser Diffraction Profiles of Particle Size Distribution

    NASA Astrophysics Data System (ADS)

    Agrawal, Y. C.; Hanes, D. M.

    2015-12-01

    In a river column, does acoustic attenuation depend solely on fines while backscatter is determined by coarse grains alone? Does a single, monotonic relationship exist between acoustic backscatter and suspended sediment concentration in a bi-modal size distribution (PSD) at some sound frequency? These questions are addressed in this paper. In-situ vertical profiles of PSD, measured with a laser diffraction instrument LISST-SL are used to compute vertical profiles of acoustic attenuation and backscattering properties. Two sets of data taken one-year apart are examined. The data are from the Cowlitz river in Washington State. Data from one day in March, 2011 reveal a bi-modal PSD that is all washload at surface, but is dominated by Rouse-like suspended sand mode lower to bottom. In this case, at low frequencies, attenuation is indeed set by the washload, while scattering is determined by sand mode except near the surface. A monotonic relationship between backscatter and suspended sediment concentration is also found, offering a calibration for a single frequency system, and rendering inversion of acoustic profiles explicit. A year later, March 2012, the water column had very little wash load, instead only a Rouse-like suspended mode existed. In this uni-modal case, both attenuation and scattering profiles were determined by the suspended load, making inversions implicit. In this latter case, the backscatter-suspended concentration had a much tighter relationship than the bi-modal earlier case, associated with a narrow size distribution of sands. These views emphasize the dramatic variability of acoustic properties of a river column in different flow regimes.

  7. Polarimetric remote sensing in oxygen A and B bands: sensitivity study and information content analysis for vertical profile of aerosols

    NASA Astrophysics Data System (ADS)

    Ding, Shouguo; Wang, Jun; Xu, Xiaoguang

    2016-05-01

    Theoretical analysis is conducted to reveal the information content of aerosol vertical profile in space-borne measurements of the backscattered radiance and degree of linear polarization (DOLP) in oxygen (O2) A and B bands. Assuming a quasi-Gaussian shape for aerosol vertical profile characterized by peak height H and half width γ (at half maximum), the Unified Linearized Vector Radiative Transfer Model (UNL-VRTM) is used to simulate the Stokes four-vector elements of upwelling radiation at the top of atmosphere (TOA) and their Jacobians with respect to H and γ. Calculations for different aerosol types and different combinations of H and γ values show that the wide range of gas absorption optical depth in O2 A and B band enables the sensitivity of backscattered DOLP and radiance at TOA to the aerosol layer at different altitudes. Quantitatively, DOLP in O2 A and B bands is found to be more sensitive to H and γ than radiance, especially over the bright surfaces (with large visible reflectance). In many O2 absorption wavelengths, the degree of freedom of signal (DFS) for retrieving H (or γ) generally increases with H (and γ) and can be close to unity in many cases, assuming that the composite uncertainty from surface and aerosol scattering properties as well as measurements is less than 5 %. Further analysis demonstrates that DFS needed for simultaneous retrieval of H and γ can be obtained from a combined use of DOLP measurements at ˜ 10-100 O2 A and B absorption wavelengths (or channels), depending on the specific values of H. The higher the aerosol layer, the fewer number of channels for DOLP measurements in O2 A and B bands are needed for characterizing H and γ. Future hyperspectral measurements of DOLP in O2 A and B bands are needed to continue studying their potential and their combination with radiance and DOLP in atmospheric window channels for retrieving the vertical profiles of aerosols, especially highly scattering aerosols, over land.

  8. 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.

  9. Near-surface fault detection by migrating back-scattered surface waves with and without velocity profiles

    NASA Astrophysics Data System (ADS)

    Yu, Han; Huang, Yunsong; Guo, Bowen

    2016-07-01

    We demonstrate that diffraction stack migration can be used to discover the distribution of near-surface faults. The methodology is based on the assumption that near-surface faults generate detectable back-scattered surface waves from impinging surface waves. We first isolate the back-scattered surface waves by muting or FK filtering, and then migrate them by diffraction migration using the surface wave velocity as the migration velocity. Instead of summing events along trial quasi-hyperbolas, surface wave migration sums events along trial quasi-linear trajectories that correspond to the moveout of back-scattered surface waves. We have also proposed a natural migration method that utilizes the intrinsic traveltime property of the direct and the back-scattered waves at faults. For the synthetic data sets and the land data collected in Aqaba, where surface wave velocity has unexpected perturbations, we migrate the back-scattered surface waves with both predicted velocity profiles and natural Green's function without velocity information. Because the latter approach avoids the need for an accurate velocity model in event summation, both the prestack and stacked migration images show competitive quality. Results with both synthetic data and field records validate the feasibility of this method. We believe applying this method to global or passive seismic data can open new opportunities in unveiling tectonic features.

  10. Differential absorption lidar (DIAL) via atmospheric aerosol (cloud) backscattering: recent results of coherent CO2 lidar measurements conducted at the Maui Space Surveillance Site

    NASA Astrophysics Data System (ADS)

    Willman, Benjamin C.; Kovacs, Mark A.

    2001-01-01

    Textron Systems, under the US Army Space and Missile Defense Command's Field Ladar Tactical Transition Demonstration program, has been evaluating coherently detected, atmospheric aerosol backscattering as a method to extend the utility of the DIAL technique. This paper present recently obtained long range, multi-wavelength DIAL measurements utilizing cloud formations and a laboratory positioned absorption test cell. Good agreement between cloud and continuous wave laboratory measurements of the absorption spectra of ammonia have been obtained.

  11. Atmospheric aerosol profiling with a bistatic imaging lidar system.

    PubMed

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

    2007-05-20

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

  12. Ozone profiles and chemical loss rates in the tropical stratosphere deduced from backscatter ultraviolet measurements

    NASA Technical Reports Server (NTRS)

    Frederick, J. E.; Hays, P. B.; Guenther, B. W.; Heath, D. F.

    1978-01-01

    Analysis of data obtained by the backscatter ultraviolet (BUV) experiment on the Atmosphere Explorer E satellite has provided equatorial ozone mixing ratio profiles for equinox and solstice conditions. The combination of these results with a pure oxygen chemical model yields the rate of odd oxygen loss due to the sum of the odd hydrogen, nitrogen, and chlorine cycles. Use of recent mid-latitude stratospheric measurements of HO(x), NO(x), and ClO(x) with the BUV data provides an independent calculation of the catalytic loss. Below 45 km the agreement between the two sets of loss rates is satisfactory. At higher altitudes the odd hydrogen cycle provides far more O(x) loss than can be tolerated by the BUV measurements if the photodissociation of O2 is the only source and has the currently accepted magnitude. The results suggest either a tropical HO(x) concentration smaller than is now believed or the presence of a very large source of odd oxygen in the upper stratosphere and lower mesosphere.

  13. Profiling measurements of metal ion distribution in thin polymer inclusion membranes by Rutherford backscattering spectrometry

    NASA Astrophysics Data System (ADS)

    Guedioura, B.; Bendjaballah, N.; Alioui, N.

    2014-05-01

    Polymer inclusion membranes (PIMs) composed of a homogeneous mixture of cellulose triacetate matrix, 2-nitro-phenyl-octyl-ether as plasticizer and tri-octyl-phosphine-oxyde as carrier were synthesized by the spin coating method. Synthesized membranes were doped with molybdenum metal ions and then characterized by four experimental techniques: thermo gravimetric and differential analyses, scanning electron microscopy (SEM), attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy and Rutherford backscattering (RBS) spectrometry using a 3.2 MeV He+ ion beam. The RBS analysis has established both the elemental composition as well as the Mo+ metal profiling of the studied PIMs. The experimental irradiation conditions were optimized in order to determine the ion fluence thresholds resulting in measurable changes in elemental composition of membranes. Changes in physico-chemical properties of the irradiated PIMs vs He+ ion fluence were observed with the ATR-FTIR analysis. Also, the SEM analysis of PIMs surfaces has revealed a porous texture, while the thermal analysis of annealed PIMs at 105°C has showed no significant changes of mass (∼1%) of the studied samples.

  14. Application of neural networks for determining optical parameters of strongly scattering media from the intensity profile of backscattered radiation

    SciTech Connect

    Kotova, S P; Maiorov, I V; Maiorova, A M

    2007-01-31

    We analyse the possibilities of simultaneous measuring three optical parameters of scattering media, namely, the scattering and absorption coefficients and the scattering anisotropy parameter by the intensity profile of backscattered radiation by using the neural network inversion method and the method of adaptive-network-based fuzzy inference system. The measurement errors of the absorption and scattering coefficients and the scattering anisotropy parameter are 20%, 5%, and 10%, respectively. (special issue devoted to multiple radiation scattering in random media)

  15. Vertical Profiles of Aerosol Optical and Microphysical Properties During a Rare Case of Long-range Transport of Mixed Biomass Burning-polluted Dust Aerosols from the Russian Federation-kazakhstan to Athens, Greece

    NASA Astrophysics Data System (ADS)

    Papayannis, Alexandros; Argyrouli, Athina; Kokkalis, Panayotis; Tsaknakis, Georgios; Binietoglou, Ioannis; Solomos, Stavros; Kazadzis, Stylianos; Samaras, Stefanos; Böckmann, Christine; Raptis, Panagiotis; Amiridis, Vassilis

    2016-06-01

    Multi-wavelength aerosol Raman lidar measurements with elastic depolarization at 532 nm were combined with sun photometry during the HYGRA-CD campaign over Athens, Greece, on May-June 2014. We retrieved the aerosol optical [3 aerosol backscatter profiles (baer) at 355-532-1064 nm, 2 aerosol extinction (aaer) profiles at 355-532 nm and the aerosol linear depolarization ratio (δ) at 532 nm] and microphysical properties [effective radius (reff), complex refractive index (m), single scattering albedo (ω)]. We present a case study of a long distance transport (~3.500-4.000 km) of biomass burning particles mixed with dust from the Russian Federation-Kazakhstan regions arriving over Athens on 21-23 May 2014 (1.7-3.5 km height). On 23 May, between 2-2.75 km we measured mean lidar ratios (LR) of 35 sr (355 nm) and 42 sr (532 nm), while the mean Ångström exponent (AE) aerosol backscatter-related values (355nm/532nm and 532nm/1064nm) were 2.05 and 1.22, respectively; the mean value of δ at 532 nm was measured to be 9%. For that day the retrieved mean aerosol microphysical properties at 2-2.75 km height were: reff=0.26 μm (fine mode), reff=2.15 μm (coarse mode), m=1.36+0.00024i, ω=0.999 (355 nm, fine mode), ω=0.992(355 nm, coarse mode), ω=0.997 (532 nm, fine mode), and ω=0.980 (532 nm, coarse mode).

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

    PubMed

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

    2013-06-01

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

  17. Micropulse lidar observations of the annual cycle of altitude profiles of aerosols and delineation of the effect of long-range transport over a tropical coastal Indian station

    NASA Astrophysics Data System (ADS)

    Mishra, Manoj; Parameswaran, Krishnaswamy; Krishna Moorthy, K.; Rajeev, Kunjukrishnapillai; Nair, Anish Kumar M.; Vengasseril Thampi, Bijoy

    2012-07-01

    Atmospheric residence time, long-range transport and climate impact of aerosols are considerably modulated by their altitude of occurrence. Aerosol loading over Indian subcontinent and the surrounding oceanic regions are strongly influenced by long-range transport of aerosols. Altitude profiles of aerosol backscatter coefficient and linear depolarization ratio (LDR) observed using dual polarization Micropulse Lidar (MPL) provide a unique tool to investigate the vertical distribution of aerosols and unambiguously identify aerosol layers, especially when the aerosol-shape characteristics are distinctly different. The value of LDR increases with non-sphericity: it is below ˜0.04 for spherical aerosols while its value typically varies in the range of 0.1-0.3 for mineral dust. This paper presents the monthly, seasonal and interannual variations in the mean altitude profiles of aerosol backscatter coefficient (β a) and LDR over a tropical coastal station in the southwest Indian Peninsula, Trivandrum (8.5°N, 77°E), observed using dual polarization MPL during the period of 2008-2011. Prominent elevated layers of mineral dust caused by the long-range transport from the West Asian Deserts is a persistent feature in the altitude band of 1-4 km during the July-August period, while its interannual variability is considerable during the other summer monsoon months of June and September. Similar elevated layers are also observed during the pre-monsoon season (March-May), albeit with relatively smaller values of LDR (0.10-0.15) compared to the summer monsoon season (LDR in the range of 0.1-0.3). Aerosol amount in the 2-5 km altitude is substantially small during September-February compared to that in March-May and July-August. Annual cycle of the monthly mean values of integrated backscatter coefficient shows a peak-to-trough ratio varying in the range of 5 to 10 in the above region. Annual variation of LDR below 1 km altitude is less pronounced. Lowest values of β a and LDR

  18. 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

  19. Vertical Profile of Aerosol Properties at Pico Mountain, Azores

    NASA Astrophysics Data System (ADS)

    Wright, K.; Mazzoleni, C.; Mazzoleni, L. R.; Dzepina, K.; Hueber, J.; China, S.; Sharma, N.

    2013-12-01

    Pico Mountain (2325m asl) is a dormant volcano in the archipelago of the Azores1500 km west of Lisbon, Portugal in the North Atlantic. It differs from typical mountain ranges such as the Alps or the Rockies, which are large and present a complex orography. Pico Mountain has a simple cone-like structure with only one main peak and is thousands of kilometers away from any other significant mountain range. In summer months, it is typical for air masses to move around the mountain rather than traveling up its face. This implies that often the peak of the mountain lies above the marine boundary layer in the free troposphere, while the lower part of the mountain is affected by marine clouds and marine air-masses. An atmospheric monitoring station, the Pico Mountain Observatory was established in 2001 in the summit caldera of the volcano at 2225m above sea level. The observatory is far from large populations or pollution sources, which makes the station ideal to study atmospheric gases and aerosols transported over long-ranges in the free troposphere. The station is reachable only by foot following a steep and strenuous hiking trail. In the summer of 2013 we began to collect vertical profiles of aerosol by carrying an instrumented backpack up to the summit of the mountain, with the goal of studying the vertical structure of atmospheric aerosols from the marine boundary layer to the free troposphere. The backpack was carried from the base of trail at 1200m asl. The backpack was equipped with the following instruments: 1. Nephelometer to measure light scattering from aerosol 2. 2-size optical particle counter (300-500 nm) 3. Portable micro-aethalometer to measure absorbing aerosols 4. SEM/TEM sampler to collect particles for off-line electron microscopy analysis 5. Battery powered data logger to measure relative humidity, temperature and pressure 6. GPS tracking device We provide a preliminary analysis of data collected in 2013 to gain insight on the vertical distribution

  20. Estimating suspended solids concentrations from backscatter intensity measured by acoustic Doppler current profiler in San Francisco Bay, California

    USGS Publications Warehouse

    Gartner, J.W.

    2004-01-01

    The estimation of mass concentration of suspended solids is one of the properties needed to understand the characteristics of sediment transport in bays and estuaries. However, useful measurements or estimates of this property are often problematic when employing the usual methods of determination from collected water samples or optical sensors. Analysis of water samples tends to undersample the highly variable character of suspended solids, and optical sensors often become useless from biological fouling in highly productive regions. Acoustic sensors, such as acoustic Doppler current profilers that are now routinely used to measure water velocity, have been shown to hold promise as a means of quantitatively estimating suspended solids from acoustic backscatter intensity, a parameter used in velocity measurement. To further evaluate application of this technique using commercially available instruments, profiles of suspended solids concentrations are estimated from acoustic backscatter intensity recorded by 1200- and 2400-kHz broadband acoustic Doppler current profilers located at two sites in San Francisco Bay, California. ADCP backscatter intensity is calibrated using optical backscatterance data from an instrument located at a depth close to the ADCP transducers. In addition to losses from spherical spreading and water absorption, calculations of acoustic transmission losses account for attenuation from suspended sediment and correction for nonspherical spreading in the near field of the acoustic transducer. Acoustic estimates of suspended solids consisting of cohesive and noncohesive sediments are found to agree within about 8-10% (of the total range of concentration) to those values estimated by a second optical backscatterance sensor located at a depth further from the ADCP transducers. The success of this approach using commercially available Doppler profilers provides promise that this technique might be appropriate and useful under certain conditions in

  1. Vertical profiles of aerosol radiative forcing - a comparison of AEROCOM phase 2 model submissions

    NASA Astrophysics Data System (ADS)

    Samset, B. H.; Myhre, G.

    2012-04-01

    Aerosols in the earth's atmosphere affect the radiation balance of the planet. The radiative forcing (RF) induced by a given aerosol burden is however sensitive to its vertical density profile, in addition to aerosol optical properties, cloud distributions and surface albedo. Differences in vertical profiles are thought to be among the causes for the large intermodel differences in RF of the aerosol direct effect. As part of the AEROCOM phase 2 direct radiative forcing experiment, this study compares 3D concentration fields of black carbon from fossil fuel burning (BC) and sulphate (SO4) from a set of major global climate models. The participating models were run using a prescribed set of emissions of aerosol and aerosol precursors and the same meteorological year. We assume that model differences due to the aerosol vertical profile can be factored out from other differences such as aerosol physics, radiative transfer or ground albedo. We consequently analyse model RF variability using profiles of normalized RF (radiative forcing per unit mass, NDRF) calculated from a single model. This tool allows us to quantify the fraction of the intermodel variability due to differences in aerosol vertical profiles. We show that there are still significant differences between both modelled vertical density profiles, treatment of aerosol physics and other factors influencing the RF profiles.

  2. Deriving Vertical Profiles of Aerosol Sizes from TES

    NASA Astrophysics Data System (ADS)

    Wolff, M. J.; Clancy, R. T.; Smith, M. D.; McConnochie, T. H.; Flittner, D. E.; Fouchet, T.

    2011-12-01

    Vertical variations in aerosol particle sizes can have a dramatic effect in their net impact on the state and evolution of the Martian atmosphere. Recent analyses of data from the Spectroscopy for the Investigation of the Characteristics of the Atmosphere of Mars (SPICAM) and the Thermal Emission Spectrometer (TES) instruments offer some long overdue progress in constraining this aspect of aerosols. However, significantly more work remains to be done along these lines in order to better constrain and inform modern dynamical simulations of the Martian atmosphere. Thus, the primary goal of our work is to perform retrievals of particle size as a function of altitude for both dust and water ice aerosols. The choice of the TES dataset, with pole-to-pole coverage over a period of nearly three martian years, provides the crucial systematic temporal and spatial sampling. Additional leverage on the particle size will be obtained by using both solarband bolometry and infrared (IR) spectroscopy. Our presentation will include: 1) A summary of our limb radiative transfer comparison/validation exercises which include Monte Carlo, Gauss-Seidel, and discrete-ordinate algorithms (including the plane-parallel source function approximation). 2) The initial results of the application of our particle size retrieval scheme to the TES observations of the 2001 planet encircling dust event. 3) A few test applications to the Mars Climate Sounder (MCS) radiance profiles (enabled by the recent solarband radiometric calibration by Bandfield and collaborators). 4) Our plans for additional retrievals (aphelion cloud season, lower optical depth locations and seasons, etc.) and the distribution of the derived profiles.

  3. The Aerosol Limb Imager: acousto-optic imaging of limb scattered sunlight for stratospheric aerosol profiling

    NASA Astrophysics Data System (ADS)

    Elash, B. J.; Bourassa, A. E.; Loewen, P. R.; Lloyd, N. D.; Degenstein, D. A.

    2015-12-01

    The Aerosol Limb Imager (ALI) is an optical remote sensing instrument designed to image scattered sunlight from the atmospheric limb. These measurements are used to retrieve spatially resolved information of the stratospheric aerosol distribution, including spectral extinction coefficient and particle size. Here we present the design, development and test results of an ALI prototype instrument. The long term goal of this work is the eventual realization of ALI on a satellite platform in low earth orbit, where it can provide high spatial resolution observations, both in the vertical and cross-track. The instrument design uses a large aperture Acousto-Optic Tunable Filter (AOTF) to image the sunlit stratospheric limb in a selectable narrow wavelength band ranging from the visible to the near infrared. The ALI prototype was tested on a stratospheric balloon flight from the Canadian Space Agency (CSA) launch facility in Timmins, Canada, in September 2014. Preliminary analysis of the hyperspectral images indicate that the radiance measurements are of high quality, and we have used these to retrieve vertical profiles of stratospheric aerosol extinction coefficient from 650-1000 nm, along with one moment of the particle size distribution. Those preliminary results are promising and development of a satellite prototype of ALI within the Canadian Space Agency is ongoing.

  4. 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.

  5. Vertical microphysical profiles of convective clouds as a tool for obtaining aerosol cloud-mediated climate forcings

    SciTech Connect

    Rosenfeld, Daniel

    2015-12-23

    Quantifying the aerosol/cloud-mediated radiative effect at a global scale requires simultaneous satellite retrievals of cloud condensation nuclei (CCN) concentrations and cloud base updraft velocities (Wb). Hitherto, the inability to do so has been a major cause of high uncertainty regarding anthropogenic aerosol/cloud-mediated radiative forcing. This can be addressed by the emerging capability of estimating CCN and Wb of boundary layer convective clouds from an operational polar orbiting weather satellite. Our methodology uses such clouds as an effective analog for CCN chambers. The cloud base supersaturation (S) is determined by Wb and the satellite-retrieved cloud base drop concentrations (Ndb), which is the same as CCN(S). Developing and validating this methodology was possible thanks to the ASR/ARM measurements of CCN and vertical updraft profiles. Validation against ground-based CCN instruments at the ARM sites in Oklahoma, Manaus, and onboard a ship in the northeast Pacific showed a retrieval accuracy of ±25% to ±30% for individual satellite overpasses. The methodology is presently limited to boundary layer not raining convective clouds of at least 1 km depth that are not obscured by upper layer clouds, including semitransparent cirrus. The limitation for small solar backscattering angles of <25º restricts the satellite coverage to ~25% of the world area in a single day. This methodology will likely allow overcoming the challenge of quantifying the aerosol indirect effect and facilitate a substantial reduction of the uncertainty in anthropogenic climate forcing.

  6. Novel Co:MgF2 lidar for aerosol profiler

    NASA Technical Reports Server (NTRS)

    Acharekar, M. A.

    1993-01-01

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

  7. The Impact of Caliop Aerosol Profiling: How Z Influences the X, Y Satellite Perspective

    NASA Astrophysics Data System (ADS)

    Campbell, J. R.; Alfaro-Contreras, R.; Buchard, V.; Toth, T. D.; Vaughan, M.; Zhang, J.

    2014-12-01

    The ever-burgeoning satellite remote sensing era has significantly improved our understanding of the role aerosol particles play in the earth-atmosphere system. Instruments such as MODIS, MISR, OMI, AVHRR, and now VIIRS, among others, are meeting a growing number of observational demands necessary for characterizing aerosol particle influence, on processes such as surface air quality, direct and semi-direct forcing and cloud indirect effects. While these passive sensors have grown to represent the community's fundamental global aerosol observing core, their datasets represent, almost exclusively, a column-integrated view of atmospheric aerosols. In contrast, however, aerosol-climate interaction is inherently sensitive to the vertical distribution of aerosol particle presence. Though the CALIOP instrument, with its relatively limited profiling swath, offers a much smaller observational scale compared with passive imagers, active-sensor aerosol profiling is increasingly adding the necessary vertical perspective required to challenge and fully characterize what has become a predominant two-dimensional global perception of aerosols. In this talk, we highlight the impact of CALIOP-based profiling, and describe how the critical third dimension is contributing to this knowledge. We introduce aerosol scale-heights and the contribution of near-surface particle presence relative to column-integrated aerosol optical depths. We describe the impact of particle profile diffusivity relative to passive-based estimates of surface air quality. The impact of accurate vertical profiling in global modeling systems is conceptualized, through benefits to downwind forecasting from accurate initialization. Sensitivities in semi-direct regional heating rate estimates are shown as a function of model-constrained aerosol vertical profiling. Finally, we highlight perhaps the most important CALIOP observation of all, relative to the passive sensors: the presence of optically-thin cirrus clouds

  8. The Global Ozone and Aerosol Profiles and Aerosol Hygroscopic Effect and Absorption Optical Depth (GOA2HEAD) Network Initiative

    NASA Astrophysics Data System (ADS)

    Gao, R. S.; Elkins, J. W.; Frost, G. J.; McComiskey, A. C.; Murphy, D. M.; Ogren, J. A.; Petropavlovskikh, I. V.; Rosenlof, K. H.

    2014-12-01

    Inverse modeling using measurements of ozone (O3) and aerosol is a powerful tool for deriving pollutant emissions. Because they have relatively long lifetimes, O3 and aerosol are transported over large distances. Frequent and globally spaced vertical profiles rather than ground-based measurements alone are therefore highly desired. Three requirements necessary for a successful global monitoring program are: Low equipment cost, low operation cost, and reliable measurements of known uncertainty. Conventional profiling using aircraft provides excellent data, but is cost prohibitive on a large scale. Here we describe a new platform and instruments meeting all three global monitoring requirements. The platform consists of a small balloon and an auto-homing glider. The glider is released from the balloon at about 5 km altitude, returning the light instrument package to the launch location, and allowing for consistent recovery of the payload. Atmospheric profiling can be performed either during ascent or descent (or both) depending on measurement requirements. We will present the specifications for two instrument packages currently under development. The first measures O3, RH, p, T, dry aerosol particle number and size distribution, and aerosol optical depth. The second measures dry aerosol particle number and size distribution, and aerosol absorption coefficient. Other potential instrument packages and the desired spatial/temporal resolution for the GOA2HEAD monitoring initiative will also be discussed.

  9. 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).

  10. Vertical profiles of cloud condensation nuclei, aerosol hygroscopicity, water uptake, and scattering across the United States

    NASA Astrophysics Data System (ADS)

    Lin, J. J.; Bougiatioti, A.; Nenes, A.; Anderson, B. E.; Beyersdorf, A. J.; Brock, C. A.; Gordon, T. D.; Lack, D.; Law, D. C.; Liao, J.; Middlebrook, A. M.; Richardson, M.; Thornhill, K. L., II; Winstead, E.; Wagner, N. L.; Welti, A.; Ziemba, L. D.

    2014-12-01

    The evolutions of vertical distributions of aerosol chemical, microphysical, hygroscopic, and optical properties present fundamental challenges to the understanding of ground-level air quality and radiative transfer, and few datasets exist to date for evaluation of atmospheric models. Data collected from recent NASA and NOAA field campaigns in the California Central Valley (DISCOVER-AQ), southeast United States (SENEX, SEAC4RS) and Texas (DISCOVER-AQ) allow for a unique opportunity to constrain vertical profiles of climate-relevant aerosol properties. This work presents in-situ aircraft measurements of cloud condensation nuclei (CCN) concentration and derivations of aerosol hygroscopicity, water uptake, and light scattering. Aerosol hygroscopicity is derived from CCN and aerosol measurements. Inorganic water uptake is calculated from aerosol composition using ISORROPIA, a chemical thermodynamic model, while organic water uptake is calculated from organic hygroscopicity. Aerosol scattering closure is performed between scattering from water uptake calculations and in-situ scattering measurements.

  11. Potential of polarization lidar to provide profiles of CCN- and INP-relevant aerosol parameters

    NASA Astrophysics Data System (ADS)

    Mamouri, R. E.; Ansmann, A.

    2015-12-01

    We investigate the potential of polarization lidar to provide vertical profiles of aerosol parameters from which cloud condensation nucleus (CCN) and ice nucleating particle (INP) number concentrations can be estimated. We show that height profiles of number concentrations of aerosol particles with radius > 50 nm (APC50, reservoir of favorable CCN) and with radius > 250 nm (APC250, reservoir of favorable INP), as well as profiles of the aerosol particle surface area concentration (ASC, used in INP parameterization) can be retrieved from lidar-derived aerosol extinction coefficients (AEC) with relative uncertainties of a factor of around 2 (APC50), and of about 25-50 % (APC250, ASC). Of key importance is the potential of polarization lidar to identify mineral dust particles and to distinguish and separate the aerosol properties of basic aerosol types such as mineral dust and continental pollution (haze, smoke). We investigate the relationship between AEC and APC50, APC250, and ASC for the main lidar wavelengths of 355, 532 and 1064 nm and main aerosol types (dust, pollution, marine). Our study is based on multiyear Aerosol Robotic Network (AERONET) photometer observations of aerosol optical thickness and column-integrated particle size distribution at Leipzig, Germany, and Limassol, Cyprus, which cover all realistic aerosol mixtures of continental pollution, mineral dust, and marine aerosol. We further include AERONET data from field campaigns in Morocco, Cabo Verde, and Barbados, which provide pure dust and pure marine aerosol scenarios. By means of a simple relationship between APC50 and the CCN-reservoir particles (APCCCN) and published INP parameterization schemes (with APC250 and ASC as input) we finally compute APCCCN and INP concentration profiles. We apply the full methodology to a lidar observation of a heavy dust outbreak crossing Cyprus with dust up to 8 km height and to a case during which anthropogenic pollution dominated.

  12. Vertical Profiles of Aerosol Volume from High Spectral Resolution Infrared Transmission Measurements: Results

    NASA Technical Reports Server (NTRS)

    Eldering, Annmarie; Kahn, Brian H.; Mills, Franklin P.; Irion, Fredrick W.; Steele, Helen M.; Gunson, Michael R.

    2004-01-01

    The high-resolution infrared absorption spectra of the Atmospheric Trace Molecule Spectroscopy (ATMOS) experiment are utilized to derive vertical profiles of sulfate aerosol volume density and extinction coefficient. Following the eruption of Mt. Pinatubo in June 1991, the ATMOS spectra obtained on three Space Shuttle missions (1992, 1993, and 1994) provide a unique opportunity to study the global stratospheric sulfate aerosol layer shortly after a major volcanic eruption and periodically during the decay phase. Synthetic sulfate aerosol spectra are fit to the observed spectra, and a global fitting inversion routine is used to derive vertical profiles of sulfate aerosol volume density. Vertical profiles of sulfate aerosol volume density for the three missions over portions of the globe are presented, with the peak in aerosol volume density occurring from as low as 10 km (polar latitudes) to as high as 20 km (subtropical latitudes). Derived aerosol volume density is as high as 2-3.5 (mu)m(exp 3) per cubic centimeter +/-10% in 1992, decreasing to 0.2-0.5 (mu)m(exp 3) per cubic centimeter +/-20% in 1994, in agreement with other experiments. Vertical extinction profiles derived from ATMOS are compared with profiles from Improved Stratospheric And Mesospheric Sounder (ISAMS) and Cryogenic Limb Array Etalon Spectrometer (CLAES) that coincide in space and time and show good general agreement. The uncertainty of the ATMOS vertical profiles is similar to CLAES and consistently smaller than ISAMS at similar altitudes.

  13. The backscatter cloud probe - a compact low-profile autonomous optical spectrometer

    NASA Astrophysics Data System (ADS)

    Beswick, K.; Baumgardner, D.; Gallagher, M.; Volz-Thomas, A.; Nedelec, P.; Wang, K.-Y.; Lance, S.

    2014-05-01

    A compact (500 cm3), lightweight (500 g), near-field, single particle backscattering optical spectrometer is described that mounts flush with the skin of an aircraft and measures the concentration and optical equivalent diameter of particles from 5 to 75 μm. The backscatter cloud probe (BCP) was designed as a real-time qualitative cloud detector primarily for data quality control of trace gas instruments developed for the climate monitoring instrument packages that are being installed on commercial passenger aircraft as part of the European Union In-Service Aircraft for a Global Observing System (IAGOS) program (http://www.iagos.org/). Subsequent evaluations of the BCP measurements on a number of research aircraft, however, have revealed it capable of delivering quantitative particle data products including size distributions, liquid-water content and other information on cloud properties. We demonstrate the instrument's capability for delivering useful long-term climatological, as well as aviation performance information, across a wide range of environmental conditions. The BCP has been evaluated by comparing its measurements with those from other cloud particle spectrometers on research aircraft and several BCPs are currently flying on commercial A340/A330 Airbus passenger airliners. The design and calibration of the BCP is described in this article, along with an evaluation of measurements made on the research and commercial aircraft. Preliminary results from more than 7000 h of airborne measurements by the BCP on two Airbus A340s operating on routine global traffic routes (one Lufthansa, the other China Airlines) show that more than 340 h of cloud data have been recorded at normal cruise altitudes (> 10 km) and more than 40% of the > 1200 flights were through clouds at some point between takeoff and landing. These data are a valuable contribution to databases of cloud properties, including sub-visible cirrus

  14. The effect of aerosol vertical profiles on satellite-estimated surface particle sulfate concentrations

    SciTech Connect

    Liu, Yang; Wang, Zifeng; Wang, Jun; Ferrare, Richard A.; Newsom, Rob K.; Welton, Ellsworth J.

    2011-02-15

    The aerosol vertical distribution is an important factor in determining the relationship between satellite retrieved aerosol optical depth (AOD) and ground-level fine particle pollution concentrations. We evaluate how aerosol profiles measured by ground-based lidar and simulated by models can help improve the association between AOD retrieved by the Multi-angle Imaging Spectroradiometer (MISR) and fine particle sulfate (SO4) concentrations using matched data at two lidar sites. At the Goddard Space Flight Center (GSFC) site, both lidar and model aerosol profiles marginally improve the association between SO4 concentrations and MISR fractional AODs, as the correlation coefficient between cross-validation (CV) and observed SO4 concentrations changes from 0.87 for the no-scaling model to 0.88 for models scaled with aerosol vertical profiles. At the GSFC site, a large amount of urban aerosols resides in the well-mixed boundary layer so the column fractional AODs are already excellent indicators of ground-level particle pollution. In contrast, at the Atmospheric Radiation Measurement Program (ARM) site with relatively low aerosol loadings, scaling substantially improves model performance. The correlation coefficient between CV and observed SO4 concentrations is increased from 0.58 for the no-scaling model to 0.76 in the GEOS-Chem scaling model, and the model bias is reduced from 17% to 9%. In summary, despite the inaccuracy due to the coarse horizontal resolution and the challenges of simulating turbulent mixing in the boundary layer, GEOS-Chem simulated aerosol profiles can still improve methods for estimating surface aerosol (SO4) mass from satellite-based AODs, particularly in rural areas where aerosols in the free troposphere and any long-range transport of aerosols can significantly contribute to the column AOD.

  15. A comparison of SAGE 1, SBUV, and Umkehr ozone profiles including a search for Umkehr aerosol effects

    NASA Technical Reports Server (NTRS)

    Newchurch, M. J.; Grams, G. W.; Cunnold, D. M.; Deluisi, J. J.

    1987-01-01

    Using a spatially weighted average for the stratospheric aerosol and gas experiment 1 (SAGE 1) events derived from an autocorrelation analysis, 337 colocated SAGE 1 and Umkehr ozone profiles are found. The total column ozone in layers two through nine measured by SAGE 1 is found to be 4.6 + or - 1.3 percent higher at the 95 percent confidence level than the approximate total column ozone measured by Umkehr. Average layer ozone differences indicate that most of this discrepancy resides in the lower layers. Intercomparison of SAGE 1, Nimbus 7 solar backscattered ultraviolet (SBUV), and Umkehr ozone at stations north of 30 deg indicates that, in layer six, Umkehr values are consistently higher than both SAGE 1 and SBUV by about 10 percent. In layer eight, SBUV ozone is higher than both SAGE 1 and SBUV by about 10 percent. In the upper stratosphere, the SAGE 1-Umkehr ozone differences are small for low stratospheric aerosol optical depth cases, but vary from -3 percent in layer six to -8 percent in layer nine for high optical depth cases.

  16. Study of vertical profiles of aerosols using tethersonde over Bay of Bengal

    NASA Astrophysics Data System (ADS)

    Manchanda, R. K.; Sinha, P. R.; Sreenivasan, S.; Subba Rao Jonnalagadda, Venkata

    Characterization of the physical, chemical and the optical properties of aerosol along with their spatial and temporal variations due to short residence time of few days to about a week, has received significant attention because of their critical role in the atmospheric radiation budget and the climate change. Since of the globe is covered by oceans, the measurement of aerosols, their altitude profiles and long range transport remains a challenge. We conducted the first ever in-situ measurements of size-segregated vertical profiles of aerosol in the marine atmospheric boundary layer (MABL) over the Bay of Bengal (BoB) using tethersonde. The observations were made at five different locations during the winter Integrated Campaign of Aerosols, gases and Radiation Budget. We present spatial distribution and the vertical behaviour of marine aerosols.

  17. Radiosonde aerosol counter for vertical profiling of atmospheric dust layers

    NASA Astrophysics Data System (ADS)

    Ulanowski, Z.; Hirst, E.; Kaye, P. H.; Harrison, R. G.; Nicoll, K. A.; Rogers, G.

    2010-05-01

    A low-cost, miniature aerosol particle counter has been developed, intended for use with balloon-borne meteorological radiosondes. It is particularly suitable for airborne mineral dust measurements. Ambient air is drawn into the counter using a diaphragm pump at a rate of 0.5 litre per minute. The counter detects particles in the airstream using a diode laser and a photodiode. Output from the photodiode is digitised into 5 size bins, with minimum particle diameters equivalent to 0.6, 1.4, 2.6, 5.4 and 10.6 micrometers. The counter is interfaced to a Vaisala RS92 radiosonde, which transmits data from the counter together with meteorological parameters and GPS-derived position to a ground based receiver at 1 Hz rate. Statistically significant particle size distributions can be obtained once a second for number concentrations down to about 100,000 particle per litre (within the measured size range), or correspondingly less at lower temporal resolutions. At the same time, the counter is capable of measuring dust number concentrations exceeding a million per litre without incurring significant errors. Soundings during the DREAME campaign in Kuwait (Ulanowski et al. EGU 2010, AS4.7) and on Cape Verde Islands (Nicoll et al. EGU 2010, AS4.7) provided dust concentration profiles with a typical vertical resolution of 4 m. Comparisons with integrated dust column size distribution measurements from AERONET sun photometers showed good agreement in two out of three cases where near-simultaneous retrievals were available. Optical thickness calculations based on the size distributions measured in Kuwait, with the assumption that the dust particles were prolate spheroids, agreed with the AERONET optical thickness at 675 nm to within 15%.

  18. Vertical profiles of aerosol volume from high-spectral-resolution infrared transmission measurements. I. Methodology.

    PubMed

    Eldering, A; Irion, F W; Chang, A Y; Gunson, M R; Mills, F P; Steele, H M

    2001-06-20

    The wavelength-dependent aerosol extinction in the 800-1250-cm(-1) region has been derived from ATMOS (atmospheric trace molecule spectroscopy) high-spectral-resolution IR transmission measurements. Using models of aerosol and cloud extinction, we have performed weighted nonlinear least-squares fitting to determine the aerosol-volume columns and vertical profiles of stratospheric sulfate aerosol and cirrus cloud volume. Modeled extinction by use of cold-temperature aerosol optical constants for a 70-80% sulfuric-acid-water solution shows good agreement with the measurements, and the derived aerosol volumes for a 1992 occultation are consistent with data from other experiments after the eruption of Mt. Pinatubo. The retrieved sulfuric acid aerosol-volume profiles are insensitive to the aerosol-size distribution and somewhat sensitive to the set of optical constants used. Data from the nonspherical cirrus extinction model agree well with a 1994 mid-latitude measurement indicating the presence of cirrus clouds at the tropopause. PMID:18357329

  19. Potential of polarization lidar to provide profiles of CCN- and INP-relevant aerosol parameters

    NASA Astrophysics Data System (ADS)

    Mamouri, Rodanthi-Elisavet; Ansmann, Albert

    2016-05-01

    We investigate the potential of polarization lidar to provide vertical profiles of aerosol parameters from which cloud condensation nucleus (CCN) and ice nucleating particle (INP) number concentrations can be estimated. We show that height profiles of particle number concentrations n50, dry considering dry aerosol particles with radius > 50 nm (reservoir of CCN in the case of marine and continental non-desert aerosols), n100, dry (particles with dry radius > 100 nm, reservoir of desert dust CCN), and of n250, dry (particles with dry radius > 250 nm, reservoir of favorable INP), as well as profiles of the particle surface area concentration sdry (used in INP parameterizations) can be retrieved from lidar-derived aerosol extinction coefficients σ with relative uncertainties of a factor of 1.5-2 in the case of n50, dry and n100, dry and of about 25-50 % in the case of n250, dry and sdry. Of key importance is the potential of polarization lidar to distinguish and separate the optical properties of desert aerosols from non-desert aerosol such as continental and marine particles. We investigate the relationship between σ, measured at ambient atmospheric conditions, and n50, dry for marine and continental aerosols, n100, dry for desert dust particles, and n250, dry and sdry for three aerosol types (desert, non-desert continental, marine) and for the main lidar wavelengths of 355, 532, and 1064 nm. Our study is based on multiyear Aerosol Robotic Network (AERONET) photometer observations of aerosol optical thickness and column-integrated particle size distribution at Leipzig, Germany, and Limassol, Cyprus, which cover all realistic aerosol mixtures. We further include AERONET data from field campaigns in Morocco, Cabo Verde, and Barbados, which provide pure dust and pure marine aerosol scenarios. By means of a simple CCN parameterization (with n50, dry or n100, dry as input) and available INP parameterization schemes (with n250, dry and sdry as input) we finally compute

  20. Long-term aerosol study on continental scale through EARLINET vertical profiles

    NASA Astrophysics Data System (ADS)

    Mona, Lucia; Pappalardo, Gelsomina; Linne, Holger; Wandinger, Ulla

    2015-04-01

    Lidar techniques offer the opportunity for investigating the aerosol vertical profiles, which is an important information for climatological, meteorological and air quality issues. EARLINET (European Aerosol Research Lidar Network) has been providing aerosol optical properties vertical profiles over Europe since May 2000. Long-term aerosol observations performed within EARLINET allows a climatological study of aerosol properties over Europe. All EARLINET stations perform almost simultaneously measurements three times per week following a scheduling established in 2000. Besides these climatological measurements, additional measurements are performed in order to monitor special events (as volcanic eruptions and desert dust intrusion), for satellite data evaluation and integrated studies and during intensive measurements campaigns. Aerosol optical properties vertical profiles are freely available at www.earlinet.org and through ACRIS data center http://www.actris.net/. This data are currently published on the CERA database with an associated doi number. Based mainly on Raman technique, EARLINET stations typically provide direct measurement of extinction profiles, and therefore of the aerosol optical depth (AOD), a key parameter for understanding the aerosol role on radiation budget. The free troposphere contribution to AOD and altitude of lofted layers are provided thanks to the vertical profiling capability of lidar technique. The representativeness of EARLINET regular scheduling for climatological studies is investigating through the comparison with AERONET and MODIS measurements. We find that the regular measurements schedule is typically sufficient for climatological studies. In addition lidar punctual measurements are representative for a larger area (1°x1°) in a climatological sense. Long term analysis of EARLINET profiles shows that the AOD in generally decreasing over Europe in agreement with both passive-sensors and in situ measurements. Mean vertical

  1. Vertical Profiles of Aerosol Optical Properties Over Central Illinois and Comparison with Surface and Satellite Measurements

    NASA Technical Reports Server (NTRS)

    Sheridan P. J.; Andrews, E.; Ogren, J A.; Tackett, J. L.; Winker, D. M.

    2012-01-01

    Between June 2006 and September 2009, an instrumented light aircraft measured over 400 vertical profiles of aerosol and trace gas properties over eastern and central Illinois. The primary objectives of this program were to (1) measure the in situ aerosol properties and determine their vertical and temporal variability and (2) relate these aircraft measurements to concurrent surface and satellite measurements. Underflights of the CALIPSO satellite show reasonable agreement in a majority of retrieved profiles between aircraft-measured extinction at 532 nm (adjusted to ambient relative humidity) and CALIPSO-retrieved extinction, and suggest that routine aircraft profiling programs can be used to better understand and validate satellite retrieval algorithms. CALIPSO tended to overestimate the aerosol extinction at this location in some boundary layer flight segments when scattered or broken clouds were present, which could be related to problems with CALIPSO cloud screening methods. The in situ aircraft-collected aerosol data suggest extinction thresholds for the likelihood of aerosol layers being detected by the CALIOP lidar. These statistical data offer guidance as to the likelihood of CALIPSO's ability to retrieve aerosol extinction at various locations around the globe.

  2. An overview of the first decade of PollyNET: an emerging network of automated Raman-polarization lidars for continuous aerosol profiling

    NASA Astrophysics Data System (ADS)

    Baars, Holger; Kanitz, Thomas; Engelmann, Ronny; Althausen, Dietrich; Heese, Birgit; Komppula, Mika; Preißler, Jana; Tesche, Matthias; Ansmann, Albert; Wandinger, Ulla; Lim, Jae-Hyun; Ahn, Joon Young; Stachlewska, Iwona S.; Amiridis, Vassilis; Marinou, Eleni; Seifert, Patric; Hofer, Julian; Skupin, Annett; Schneider, Florian; Bohlmann, Stephanie; Foth, Andreas; Bley, Sebastian; Pfüller, Anne; Giannakaki, Eleni; Lihavainen, Heikki; Viisanen, Yrjö; Hooda, Rakesh Kumar; Nepomuceno Pereira, Sérgio; Bortoli, Daniele; Wagner, Frank; Mattis, Ina; Janicka, Lucja; Markowicz, Krzysztof M.; Achtert, Peggy; Artaxo, Paulo; Pauliquevis, Theotonio; Souza, Rodrigo A. F.; Prakesh Sharma, Ved; Gideon van Zyl, Pieter; Beukes, Johan Paul; Sun, Junying; Rohwer, Erich G.; Deng, Ruru; Mamouri, Rodanthi-Elisavet; Zamorano, Felix

    2016-04-01

    A global vertically resolved aerosol data set covering more than 10 years of observations at more than 20 measurement sites distributed from 63° N to 52° S and 72° W to 124° E has been achieved within the Raman and polarization lidar network PollyNET. This network consists of portable, remote-controlled multiwavelength-polarization-Raman lidars (Polly) for automated and continuous 24/7 observations of clouds and aerosols. PollyNET is an independent, voluntary, and scientific network. All Polly lidars feature a standardized instrument design with different capabilities ranging from single wavelength to multiwavelength systems, and now apply unified calibration, quality control, and data analysis. The observations are processed in near-real time without manual intervention, and are presented online at http://polly.tropos.de/. The paper gives an overview of the observations on four continents and two research vessels obtained with eight Polly systems. The specific aerosol types at these locations (mineral dust, smoke, dust-smoke and other dusty mixtures, urban haze, and volcanic ash) are identified by their Ångström exponent, lidar ratio, and depolarization ratio. The vertical aerosol distribution at the PollyNET locations is discussed on the basis of more than 55 000 automatically retrieved 30 min particle backscatter coefficient profiles at 532 nm as this operating wavelength is available for all Polly lidar systems. A seasonal analysis of measurements at selected sites revealed typical and extraordinary aerosol conditions as well as seasonal differences. These studies show the potential of PollyNET to support the establishment of a global aerosol climatology that covers the entire troposphere.

  3. Raman Lidar Profiling of Aerosols Over the Central US; Diurnal Variability and Comparisons with the GOCART Model

    NASA Technical Reports Server (NTRS)

    Ferrare, R. A.; Chin, M.; Clayton, M.; Turner, D.

    2002-01-01

    We use profiles of aerosol extinction, water vapor mixing ratio, and relative humidity measured by the ARM SGP Raman lidar in northern Oklahoma to show how the vertical distributions of aerosol extinction and water vapor vary throughout the diurnal cycle. While significant (20-30%) variations in aerosol extinction occurred near the surface as well as aloft, smaller (approximately 10%) variations were observed in the diurnal variability of aerosol optical thickness (AOT). The diurnal variations in aerosol extinction profiles are well correlated with corresponding variations in the average relative humidity profiles. The water vapor mixing ratio profiles and integrated water vapor amounts generally show less diurnal variability. The Raman lidar profiles are also used to evaluate the aerosol optical thickness and aerosol extinction profiles simulated by the GOCART global aerosol model. Initial comparisons show that the AOT simulated by GOCART was in closer agreement with the AOT derived from the Raman lidar and Sun photometer measurements during November 2000 than during September 2000. For both months, the vertical variability in average aerosol extinction profiles simulated by GOCART is less than the variability in the corresponding Raman lidar profiles.

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

    SciTech Connect

    Ferrare, Richard A.

    2002-08-19

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

  5. Improved stratospheric aerosol extinction profiles from SCIAMACHY: validation and sample results

    NASA Astrophysics Data System (ADS)

    von Savigny, C.; Ernst, F.; Rozanov, A.; Hommel, R.; Eichmann, K.-U.; Rozanov, V.; Burrows, J. P.; Thomason, L. W.

    2015-12-01

    Stratospheric aerosol extinction profiles have been retrieved from SCIAMACHY/Envisat measurements of limb-scattered solar radiation. The retrieval is an improved version of an algorithm presented earlier. The retrieved aerosol extinction profiles are compared to co-located aerosol profile measurements from the SAGE II solar occultation instrument at a wavelength of 525 nm. Comparisons were carried out with two versions of the SAGE II data set (version 6.2 and the new version 7.0). In a global average sense the SCIAMACHY and the SAGE II version 7.0 extinction profiles agree to within about 10 % for altitudes above 15 km. Larger relative differences (up to 40 %) are observed at specific latitudes and altitudes. We also find differences between the two SAGE II data versions of up to 40 % for specific latitudes and altitudes, consistent with earlier reports. Sample results on the latitudinal and temporal variability of stratospheric aerosol extinction and optical depth during the SCIAMACHY mission period are presented. The results confirm earlier reports that a series of volcanic eruptions is responsible for the increase in stratospheric aerosol optical depth from 2002 to 2012. Above about an altitude of 28 km, volcanic eruptions are found to have negligible impact in the period 2002-2012.

  6. Improved stratospheric aerosol extinction profiles from SCIAMACHY: validation and sample results

    NASA Astrophysics Data System (ADS)

    von Savigny, C.; Ernst, F.; Rozanov, A.; Hommel, R.; Eichmann, K.-U.; Rozanov, V.; Burrows, J. P.; Thomason, L. W.

    2015-08-01

    Stratospheric aerosol extinction profiles have been retrieved from SCIAMACHY/Envisat measurements of limb-scattered solar radiation. The retrieval is an improved version of an algorithm presented earlier. The retrieved aerosol extinction profiles are compared to co-located aerosol profile measurements with the SAGE II solar occultation instrument at a wavelength of 525 nm. Comparisons were carried out with two versions of the SAGE II data set (version 6.2 and the new version 7.0). In a global average sense the SCIAMACHY and the SAGE II version 7.0 extinction profiles agree to within about 10 % for altitudes above 15 km. Larger relative differences (up to 40 %) are observed at specific latitudes and altitudes. We also find differences between the two SAGE II data versions of up to 40 % for specific latitudes and altitudes. Sample results on the latitudinal and temporal variability of stratospheric aerosol extinction and optical depth during the SCIAMACHY mission period are presented. The results indicate that a series of volcanic eruptions is responsible for the increase in stratospheric aerosol optical depth from 2002 to 2012. Above about 28 km altitude volcanic eruptions are found to have negligible impact in the period 2002 to 2012.

  7. 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

  8. Analysis of atmospheric vertical profiles in the presence of desert dust aerosols

    NASA Astrophysics Data System (ADS)

    Costa, M. J.; Obregón, M. A.; Pereira, S.; Salgueiro, V.; Potes, M.; Couto, F. T.; Salgado, R.; Bortoli, D.; Silva, A. M.

    2015-12-01

    The present work aims at studying a very recent episode of desert dust transport that affected Iberia in mid May 2015. The dust aerosols were detected over Évora, where a varied set of instrumentation for aerosol measurements is installed, including: a CIMEL sunphotometer integrated in AERONET, a Raman Lidar and a TEOM monitor, as well as ceilometer and a microwave radiometer (profiler). The aerosol occurrence, detected using the columnar, vertically-resolved and in situ measurements, was characterized by a fairly high aerosol optical thickness that reached a value of 1.0 at 440 nm and showed mass concentration peaks at the surface of the order of 100 μg/m3. Subsequently, the tropospheric vertical profiles of humidity and temperature obtained with the passive microwave (MW) radiometer are analysed in order to distinguish possible modifications that can be connected with the transport of desert dust. Modelling results are also examined and the total, SW and LW radiative forcings are investigated, taking into account the different vertical profiles obtained during the desert dust occurrence. It is found that the differences in the atmospheric profiles mostly affect the LW radiative forcing, with an underestimation of about 30% when the actual vertical profile is not considered.

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

    NASA Astrophysics Data System (ADS)

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

    2013-11-01

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

  10. Profile and Morphology of Fungal Aerosols Characterized by Field Emission Scanning Electron Microscopy (FESEM)

    PubMed Central

    Afanou, Komlavi Anani; Straumfors, Anne; Skogstad, Asbjørn; Skaar, Ida; Hjeljord, Linda; Skare, Øivind; Green, Brett James; Tronsmo, Arne; Eduard, Wijnand

    2016-01-01

    Fungal aerosols consist of spores and fragments with diverse array of morphologies; however, the size, shape, and origin of the constituents require further characterization. In this study, we characterize the profile of aerosols generated from Aspergillus fumigatus, A. versicolor, and Penicillium chrysogenum grown for 8 weeks on gypsum boards. Fungal particles were aerosolized at 12 and 20 L min−1 using the Fungal Spore Source Strength Tester (FSSST) and the Stami particle generator (SPG). Collected particles were analyzed with field emission scanning electron microscopy (FESEM). We observed spore particle fraction consisting of single spores and spore aggregates in four size categories, and a fragment fraction that contained submicronic fragments and three size categories of larger fragments. Single spores dominated the aerosols from A. fumigatus (median: 53%), while the submicronic fragment fraction was the highest in the aerosols collected from A. versicolor (median: 34%) and P. chrysogenum (median: 31%). Morphological characteristics showed near spherical particles that were only single spores, oblong particles that comprise some spore aggregates and fragments (<3.5 μm), and fiber-like particles that regroup chained spore aggregates and fragments (>3.5 μm). Further, the near spherical particles dominated the aerosols from A. fumigatus (median: 53%), while oblong particles were dominant in the aerosols from A. versicolor (68%) and P. chrysogenum (55%). Fiber-like particles represented 21% and 24% of the aerosols from A. versicolor and P. chrysogenum, respectively. This study shows that fungal particles of various size, shape, and origin are aerosolized, and supports the need to include a broader range of particle types in fungal exposure assessment. PMID:26855468

  11. Profile of heating rate due to aerosols using lidar and skyradiometer in SKYNET Hefei site

    NASA Astrophysics Data System (ADS)

    Wang, Z.; Liu, D.; Xie, C.

    2015-12-01

    Atmospheric aerosols have a significant impact on climate due to their important role in modifying atmosphere energy budget. On global scale, the direct radiative forcing is estimated to be in the range of -0.9 to -0.1 Wm-2 for aerosols [1]. Yet, these estimates are subject to very large uncertainties because of uncertainties in spatial and temporal variations of aerosols. At local scales, as aerosol properties can vary spatially and temporally, radiative forcing due to aerosols can be also very different and it can exceed the global value by an order of magnitude. Hence, it is very important to investigate aerosol loading, properties, and radiative forcing due to them in detail on local regions of climate significance. Haze and dust events in Hefei, China are explored by Lidar and Skyradiometer. Aerosol optical properties including the AOD, SSA, AAE and size distribution are analysed by using the SKYRAD.PACK [2] and presented in this paper. Furthermore, the radiative forcing due to aerosols and the heating rate in the ATM are also calculated using SBDART model [3]. The results are shown that the vertical heating rate is tightly related to aerosol profile. References: 1. IPCC. 2007. Climate Change 2007: The Physical Science Basic. Contribution of Working Group I Contribution to the Intergovernmental Panel on Climate Change Fourth Assessment Report. Solomon S, Qing D H, Manning M, et al. eds., Cambridge University Press, Cambridge, United Kingdom and New York, N Y, USA. 2. Nakajima, T., G. Tonna, R. Rao, Y. Kaufman, and B. Holben, 1996: Use of sky brightness measurements from ground for remote sensing of particulate poly dispersions, Appl. Opt., 35, 2672-2686. 3. Ricchiazzi et al 1998. SBDART: a research and teaching software tool for plane-parallel radiative transfer in the Earth's atmosphere,Bulletin of the American Meteorological Society,79,2101-2114.

  12. Vertical Profiles of Cloud Condensation Nuclei, Condensation Nuclei, Optical Aerosol, Aerosol Optical Properties, and Aerosol Volatility Measured from Balloons

    NASA Technical Reports Server (NTRS)

    Deshler, T.; Snider, J. R.; Vali, G.

    1998-01-01

    Under the support of this grant a balloon-borne gondola containing a variety of aerosol instruments was developed and flown from Laramie, Wyoming, (41 deg N, 105 deg W) and from Lauder, New Zealand (45 deg S, 170 deg E). The gondola includes instruments to measure the concentrations of condensation nuclei (CN), cloud condensation nuclei (CCN), optically detectable aerosol (OA.) (r greater than or equal to 0.15 - 2.0 microns), and optical scattering properties using a nephelometer (lambda = 530 microns). All instruments sampled from a common inlet which was heated to 40 C on ascent and to 160 C on descent. Flights with the CN counter, OA counter, and nephelometer began in July 1994. The CCN counter was added in November 1994, and the engineering problems were solved by June 1995. Since then the flights have included all four instruments, and were completed in January 1998. Altogether there were 20 flights from Laramie, approximately 5 per year, and 2 from Lauder. Of these there were one or more engineering problems on 6 of the flights from Laramie, hence the data are somewhat limited on those 6 flights, while a complete data set was obtained from the other 14 flights. Good CCN data are available from 12 of the Laramie flights. The two flights from Lauder in January 1998 were successful for all measurements. The results from these flights, and the development of the balloon-bome CCN counter have formed the basis for five conference presentations. The heated and unheated CN and OA measurements have been used to estimate the mass fraction of the aerosol volatile, while comparisons of the nephelometer measurements were used to estimate the light scattering, associated with the volatile aerosol. These estimates were calculated for 0.5 km averages of the ascent and descent data between 2.5 km and the tropopause, near 11.5 km.

  13. Aerosol and trace gas profile retrievals from MAX-DOAS observations using simple least squares methods

    NASA Astrophysics Data System (ADS)

    Wagner, Thomas; Beirles, Steffen; Shaiganfar, Reza

    2010-05-01

    Multi-AXis (MAX-) DOAS observations have become a widely used technique for the retrieval of atmospheric profiles of trace gases and aerosols. Since the information content of MAX-DOAS observations is limited, usually optimal estimation techniques are used for profile inversion, and a-priori assumptions are needed. In contrast, in our retrieval we limit the retrieved parameter to few basic profile parameters (e.g. profile shape and integrated column density), which are retrieved without further a-priori assumptions. The retrieval is instead based on simple least squares methods. Despite the simple retrieval scheme, our method has the advantage that it is very robust and stable. It also yields the most important parameters with good accuracy (e.g. total aerosol optical depth, total tropospheric trace gas column density, surface aerosol extinction, surface trace gas mixing ratio). Some of these parameters can even be retrieved for cloudy conditions. We present MAX-DOAS results from two measurement campaigns: The CINDI campaign in Cabauw, The Netherlands, in 2009 and the FORMAT campaign in Milano, Italy, in 2003. Results for aerosols, NO2, and HCHO, are presented and compared to independent measurements.

  14. Optical Modeling and Interpretation of TRACE-P Aerosol Measurements

    NASA Astrophysics Data System (ADS)

    Grant, W. B.; Anderson, B. E.; Browell, E. V.; Butler, C. F.; Brackett, V. G.; Jordan, C. E.

    2002-12-01

    The NASA Langley airborne UV Differential Absorption Lidar (DIAL) system participated in the NASA-sponsored Transport and Atmospheric Chemistry near the Equator-Pacific (TRACE-P) mission, designed to study transport and transformation of emissions from Asia, from February 26 to April 9, 2001. The UV DIAL system measures backscatter in both nadir and zenith at 1064, 600, and 300 nm and depolarization ratio in the nadir at 600 nm. From the lidar backscatter measurement, the aerosol scattering ratio (ASR) is determined. The ASR is the ratio of aerosol backscatter to molecular backscatter and is derived by dividing the total backscatter by a standard atmosphere molecular density profile then normalizing in some low-aerosol region of the atmosphere. The wavelength dependence of aerosol backscatter, which is related to aerosol size, is determined from the ASRs at 1064 and 600 nm. The depolarization ratio, which is sensitive to irregularly shaped particles, is used to determine the presence of dust. Dust encountered during this mission originated primarily in China, but also in India and Africa. In situ instruments onboard the DC-8 provide additional information such as meteorological parameters, aerosol size distributions and chemical composition, and gas concentrations. These in situ data are being used along with the ASRs to help determine the aerosol optical properties. These optical properties will then enable the use of the extensive lidar profiles to achieve the goal of estimating the effects of aerosols on radiative forcing of the atmosphere over the western Pacific as well as over Asia near the coast.

  15. Vertical profile and aerosol size distribution measurements in Iceland (LOAC)

    NASA Astrophysics Data System (ADS)

    Dagsson Waldhauserova, Pavla; Olafsson, Haraldur; Arnalds, Olafur; Renard, Jean-Baptiste; Vignelles, Damien; Verdier, Nicolas

    2014-05-01

    Cold climate and high latitudes regions contain important dust sources where dust is frequently emitted, foremost from glacially-derived sediments of riverbeds or ice-proximal areas (Arnalds, 2010; Bullard, 2013). Iceland is probably the most active dust source in the arctic/sub-arctic region (Dagsson-Waldhauserova, 2013). The frequency of days with suspended dust exceeds 34 dust days annually. Icelandic dust is of volcanic origin; it is very dark in colour and contains sharp-tipped shards with bubbles. Such properties allow even large particles to be easily transported long distances. Thus, there is a need to better understand the spatial and temporal variability of these dusts. Two launch campaigns of the Light Optical Aerosols Counter (LOAC) were conducted in Iceland with meteorological balloons. LOAC use a new optical design that allows to retrieve the size concentrations in 19 size classes between 0.2 and 100 microm, and to provide an estimate of the main nature of aerosols. Vertical stratification and aerosol composition of the subarctic atmosphere was studied in detail. The July 2011 launch represented clean non-dusty season with low winds while the November 2013 launch was conducted during the high winds after dusty period. For the winter flight (performed from Reykjavik), the nature of aerosols strongly changed with altitude. In particular, a thin layer of volcanic dust was observed at an altitude of 1 km. Further LOAC measurements are needed to understand the implication of Icelandic dust to the Arctic warming and climate change. A new campaign of LAOC launches is planned for May 2014. Reference: Arnalds, O., 2010. Dust sources and deposition of aeolian materials in Iceland. Icelandic Agricultural Sciences 23, 3-21. Bullard, J.E., 2013. Contemporary glacigenic inputs to the dust cycle. Earth Surface Processes and Landforms 38, 71-89. Dagsson-Waldhauserova, P., Arnalds O., Olafsson H. 2013. Long-term frequency and characteristics of dust storm events in

  16. The Aerosol Limb Imager: acousto-optic imaging of limb-scattered sunlight for stratospheric aerosol profiling

    NASA Astrophysics Data System (ADS)

    Elash, B. J.; Bourassa, A. E.; Loewen, P. R.; Lloyd, N. D.; Degenstein, D. A.

    2016-03-01

    The Aerosol Limb Imager (ALI) is an optical remote sensing instrument designed to image scattered sunlight from the atmospheric limb. These measurements are used to retrieve spatially resolved information of the stratospheric aerosol distribution, including spectral extinction coefficient and particle size. Here we present the design, development and test results of an ALI prototype instrument. The long-term goal of this work is the eventual realization of ALI on a satellite platform in low earth orbit, where it can provide high spatial resolution observations, both in the vertical and cross-track. The instrument design uses a large-aperture acousto-optic tunable filter (AOTF) to image the sunlit stratospheric limb in a selectable narrow wavelength band ranging from the visible to the near infrared. The ALI prototype was tested on a stratospheric balloon flight from the Canadian Space Agency (CSA) launch facility in Timmins, Canada, in September 2014. Preliminary analysis of the hyperspectral images indicates that the radiance measurements are of high quality, and we have used these to retrieve vertical profiles of stratospheric aerosol extinction coefficient from 650 to 1000 nm, along with one moment of the particle size distribution. Those preliminary results are promising and development of a satellite prototype of ALI within the Canadian Space Agency is ongoing.

  17. Determination of particle-induced structural disorder depth profile in crystals using the grazing-angle incidence hard x-ray backscattering diffraction technique

    NASA Astrophysics Data System (ADS)

    Bezirganyan, Hakob (Jacob P.; Bezirganyan, Siranush E.; Bezirganyan, Petros H., Jr.; Bezirganyan, Hayk H., Jr.

    2011-12-01

    In this theoretical paper, we propose an x-ray imaging method for determination of particle-induced structural disorder depth profile in the crystalline materials based on the extremely sensitive, high-resolution, and non-destructive grazing-angle incidence hard x-ray backscattering diffraction technique. A peculiar value of the Bragg angle is discovered within the specular beam suppression angular region for which the curve of x-ray reflectivity is very close to the profile of the corresponding structural disorder. The coincidence presents a unique opportunity for the direct registration of the structural disorder depth profile in particle-irradiated crystals. This paper is dedicated to Professor Dr Petros H Bezirganyan on the occasion of his 95th birthday on 15th December 2011.

  18. Developments in the SediView Technique for the processing of ADCP backscatter data to extract suspended sediment concentration profiles in flocculated sediments

    NASA Astrophysics Data System (ADS)

    Taylor, Jon; Manning, Andrew; Crossouard, Neil

    2014-05-01

    From its appearance in the 1980's researchers have recognised the possibilities offered by Acoustic Doppler Current Profiler's (ADCP's) as a means of obtaining information on fluid motion and concentration profiles in both muddy and sandy environments. To date much research effort has been directed in using ADCP's to indirectly observe variations in sandy sediments in suspension using the intensity of the backscattered energy returned from an ADCP and indeed to applications involving mixed suspensions of Sandy and Silty sediments. Studies of naturally flocculating sediment suspensions have however been limited due to practical difficulties in obtaining measurements of floc properties and the incomplete understanding of the interaction taking place between high frequency sound waves and the flocculated particles whilst those that are available have tended to be based on academic studies utilising multi-frequency acoustic sensors rather than the more ubiquitous Acoustic Doppler profilers used in commercial marine monitoring applications and hence their findings are limited in their application. In response to the need to provide water column concentration estimates for engineering applications the Sediview™ method was developed as a means of analysing acoustic backscatter data collected using standard ADCP profilers by means of a robust field methodology supported by software tools and the approach been applied to datasets collected in estuarine and fluvial environments worldwide through it's application on dredging and maritime engineering projects. The poster describes the application of Sediview™ methodology to the application of determining sediment concentration estimates from flocculated sediments measured at a site located within the Turbidity Maximum Zone of the Thames Estuary, UK, and in particular the application of a dual frequency approach to the problem. The experimental investigations described focused on the Acoustic backscatter from ADCPs

  19. 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

  20. Ceilometer calibration for retrieval of aerosol optical properties

    NASA Astrophysics Data System (ADS)

    Jin, Yoshitaka; Kai, Kenji; Kawai, Kei; Nagai, Tomohiro; Sakai, Tetsu; Yamazaki, Akihiro; Uchiyama, Akihiro; Batdorj, Dashdondog; Sugimoto, Nobuo; Nishizawa, Tomoaki

    2015-03-01

    Ceilometers are durable compact backscatter lidars widely used to detect cloud base height. They are also useful for measuring aerosols. We introduced a ceilometer (CL51) for observing dust in a source region in Mongolia. For retrieving aerosol profiles with a backscatter lidar, the molecular backscatter signal in the aerosol free heights or system constant of the lidar is required. Although the system constant of the ceilometer is calibrated by the manufacturer, it is not necessarily accurate enough for the aerosol retrieval. We determined a correction factor, which is defined as the ratio of true attenuated backscattering coefficient to the measured attenuated backscattering coefficient, for the CL51 ceilometer using a dual-wavelength Mie-scattering lidar in Tsukuba, Japan before moving the ceilometer to Dalanzadgad, Mongolia. The correction factor determined by minimizing the difference between the ceilometer and lidar backscattering coefficients was approximately 1.2±0.1. Applying the correction to the CL51 signals, the aerosol optical depth (AOD) agreed well with the sky-radiometer AOD during the observation period (13-17 February 2013) in Tsukuba (9 ×10-3 of mean square error). After moving the ceilometer to Dalanzadgad, however, the AOD observed with the CL51 (calibrated by the correction factor determined in Tsukuba) was approximately 60% of the AErosol RObotic NETwork (AERONET) sun photometer AOD. The possible causes of the lower AOD results are as follows: (1) the limited height range of extinction integration (< 3 km); (2) change in the correction factor during the ceilometer transportation or with the window contamination in Mongolia. In both cases, on-site calibrations by dual-wavelength lidar are needed. As an alternative method, we showed that the backward inversion method was useful for retrieving extinction coefficients if the AOD was larger than 1.5. This retrieval method does not require the system constant and molecular backscatter signals

  1. Autonomous Ozone and Aerosol LIDAR Profiling of the Troposphere: A Synergistic Approach

    NASA Astrophysics Data System (ADS)

    Strawbridge, K. B.

    2015-12-01

    LIDAR technology is an excellent tool to probe the complex vertical structure of the atmosphere at high spatial and temporal resolution. This provides the critical vertical context for the interpretation of ground-based chemistry measurements, airborne measurements and model/satellite verification and validation. In recent years, Environment Canada has designed several autonomous aerosol LIDAR systems for deployment across several regions of Canada. The current system builds on the successes of these autonomous LIDARS but using a synergistic approach by combining tropospheric ozone DIAL (Differential Absorption LIDAR) technology with simultaneous 3+2+1 aerosol LIDAR measurements. It operates 24 hours a day, seven days a week except during precipitation events. The system is operated remotely and the data are updated every hour to a website to allow near real-time capability. A few case studies are shown emphasizing the synergistic approach of coupling ozone and aerosol profiles to better understand air quality impacts on local and regional scales.

  2. Post-volcanic stratospheric aerosol decay as measured by lidar

    NASA Technical Reports Server (NTRS)

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

    1978-01-01

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

  3. Vertical Resolved Dust Mass Concentration and Backscatter Coefficient Retrieval of Asian Dust Plume Using Quartz Raman Channel in Lidar Measurements

    NASA Astrophysics Data System (ADS)

    Noh, Young M.; Mueller, Detlef; Shin, Sungkyun

    2016-06-01

    In this work, we present a method for estimating vertical resolved mass concentration of dust immersed in Asian dust plume using Raman scattering of quartz (silicon dioxide, silica). During the Asian dust period of March 15, 16, and 21 in 2010, Raman lidar measurements detected the presence of quartz, and successfully showed the vertical profiles of the quartz backscatter coefficient. Since the Raman backscatter coefficient was connected with the Raman backscatter differential cross section and the number density of quartz molecules, the mass concentration of quartz in the atmosphere can be estimated from the quartz backscatter coefficient. The weight percentage from 40 to 70 % for quartz in the Asian dust was estimated from references. The vertical resolved mass concentration of dust was estimated by quartz mass concentration and weight percentage. We also present a retrieval method to obtain dust backscatter coefficient from the mixed Asian dust and pollutant layer. OPAC (Optical Properties of Aerosol and Clouds) simulations were conducted to calculate dust backscatter coefficient. The retrieved dust mass concentration was used as an input parameter for the OPAC calculations. These approaches in the study will be useful for characterizing the quartz dominated in the atmospheric aerosols and estimating vertical resolved mass concentration of dust. It will be especially applicable for optically distinguishing the dust and non-dust aerosols in studies on the mixing state of Asian dust plume. Additionally, the presented method combined with satellite observations is enable qualitative and quantitative monitoring for Asian dust.

  4. 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.

  5. Balloonborne measurements of ozone and aerosol profiles at McMurdo Station, Antarctica, during the austral spring of 1992

    SciTech Connect

    Johnson, B.J.; Deshler, T. )

    1993-01-01

    This paper reports some of the findings of an overall study of the ozone hole over Antarctica. Vertical profiles of ozone and aerosols were measured, and the inclusion of aerosols from the June 1991 eruption of Mount Pinatubo was of particular interest. 4 refs., 2 figs.

  6. 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.

  7. 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.

  8. A Multi-Instrument Approach for Characterizing the Vertical Structure of Aerosol Properties: Case Studies in the Pacific Basin Troposphere

    NASA Technical Reports Server (NTRS)

    Redemann, J.; Turco, R. P.; Pueschel, R. F.; Fenn, M. A.; Browell, E. V.; Grant, W. B.

    1998-01-01

    During February/March 1994, a series of aircraft-based aerosol measurements were carried out in the Pacific Basin troposphere using a differential absorption lidar system deployed by NASA Langley, and optical spectrometer probes and a wire-impactor system operated by NASA Ames. A modified Klett inversion algorithm was applied to extract altitude profiles of aerosol backscattering from the IR lidar signal. The algorithm that we have designed for this purpose utilizes the in situ aerosol measurements to normalize the lidar profile at the aircraft altitude and to supply the lidar ratio as a function of height. The lidar-derived aerosol backscattering coefficients were then compared to the backscattering coefficients calculated from the in situ measurements. During several local aircraft descents, we found good agreement between the remote lidar and in situ results for the absolute value of the aerosol backscattering coefficient and its altitude variation only when we allowed for several layers with different aerosol refractive indices. The agreement validates our lidar calibration method and provides an indication of the variation in aerosol refractive index as a function of altitude. Two of the three case studies performed in this paper reveal layers of anthropogenic aerosols transported long distances into the Pacific Basin troposphere. A third case implies the existence of a layer of dustlike aerosol particles in the lower troposphere, most likely of Asian origin.

  9. A sensitivity study on the retrieval of aerosol vertical profiles using the oxygen A-band

    NASA Astrophysics Data System (ADS)

    Colosimo, S. F.; Natraj, V.; Sander, S. P.; Stutz, J.

    2015-11-01

    Atmospheric absorption in the O2 A-band (12 950-13 200 cm-1) offers a unique opportunity to retrieve aerosol extinction profiles from space-borne measurements due to the large dynamic range of optical thickness in that spectral region. Absorptions in strong O2 lines are saturated; therefore, any radiance measured in these lines originates from scattering in the upper part of the atmosphere. Outside of O2 lines, or in weak lines, the atmospheric column absorption is small, and light penetrates to lower atmospheric layers, allowing for the quantification of aerosols and other scatterers near the surface. While the principle of aerosol profile retrieval using O2 A-band absorption from space is well known, a thorough quantification of the information content, i.e., the amount of vertical profile information that can be obtained, and the dependence of the information content on the spectral resolution of the measurements, has not been thoroughly conducted. Here, we use the linearized vector radiative transfer model VLIDORT to perform spectrally resolved simulations of atmospheric radiation in the O2 A-band in the presence of aerosol for four different generic scenarios: Urban, Highly polluted, Elevated layer, and Marine-Arctic. The high-resolution radiances emerging from the top of the atmosphere are degraded to different spectral resolutions, simulating spectrometers with different resolving powers. We use optimal estimation theory to quantify the information content in the aerosol profile retrieval with respect to different aerosol parameters and instrument spectral resolutions. The simulations show that better spectral resolution generally leads to an increase in the total amount of information that can be retrieved, with the number of degrees of freedom (DoF) varying between 0.34-2.11 at low resolution (5 cm-1) to 3.43-5.92 at high resolution (0.05 cm-1) for the four different cases. A particularly strong improvement was found in the retrieval of tropospheric

  10. Vertical profiling of aerosol hygroscopic properties in the planetary boundary layer during the PEGASOS campaigns

    NASA Astrophysics Data System (ADS)

    Rosati, Bernadette; Gysel, Martin; Rubach, Florian; Mentel, Thomas F.; Goger, Brigitta; Poulain, Laurent; Schlag, Patrick; Miettinen, Pasi; Pajunoja, Aki; Virtanen, Annele; Klein Baltink, Henk; Bas Henzing, J. S.; Größ, Johannes; Gobbi, Gian Paolo; Wiedensohler, Alfred; Kiendler-Scharr, Astrid; Decesari, Stefano; Facchini, Maria Cristina; Weingartner, Ernest; Baltensperger, Urs

    2016-06-01

    Vertical profiles of the aerosol particles hygroscopic properties, their mixing state as well as chemical composition were measured above northern Italy and the Netherlands. An aerosol mass spectrometer (AMS; for chemical composition) and a white-light humidified optical particle spectrometer (WHOPS; for hygroscopic growth) were deployed on a Zeppelin NT airship within the PEGASOS project. This allowed one to investigate the development of the different layers within the planetary boundary layer (PBL), providing a unique in situ data set for airborne aerosol particles properties in the first kilometre of the atmosphere. Profiles measured during the morning hours on 20 June 2012 in the Po Valley, Italy, showed an increased nitrate fraction at ˜ 100 m above ground level (a.g.l.) coupled with enhanced hygroscopic growth compared to ˜ 700 m a. g. l. This result was derived from both measurements of the aerosol composition and direct measurements of the hygroscopicity, yielding hygroscopicity parameters (κ) of 0.34 ± 0.12 and 0.19 ± 0.07 for 500 nm particles, at ˜ 100 and ˜ 700 m a. g. l., respectively. The difference is attributed to the structure of the PBL at this time of day which featured several independent sub-layers with different types of aerosols. Later in the day the vertical structures disappeared due to the mixing of the layers and similar aerosol particle properties were found at all probed altitudes (mean κ ≈ 0.18 ± 0.07). The aerosol properties observed at the lowest flight level (100 m a. g. l.) were consistent with parallel measurements at a ground site, both in the morning and afternoon. Overall, the aerosol particles were found to be externally mixed, with a prevailing hygroscopic fraction. The flights near Cabauw in the Netherlands in the fully mixed PBL did not feature altitude-dependent characteristics. Particles were also externally mixed and had an even larger hygroscopic fraction compared to the results in Italy. The mean κ from

  11. 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.

  12. 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.

  13. Aerosol studies in mid-latitude coastal environments in Australia

    NASA Technical Reports Server (NTRS)

    Young, S. A.; Cutten, D.; Lynch, M. J.; Davies, J. E.

    1986-01-01

    The results of the evaluation of several inversion procedures that were used to select one which provides the most accurate atmospheric extinction profiles for small aerosol extinction coefficients (that often predominate in the maritime airmass) are presented. Height profiles of atmospheric extinction calculated by a two component atmospheric solution to the LIDAR equation will be compared with corresponding in-situ extinction profiles based on the size distribution profiles obtained in Western Australia. Values of the aerosol backscatter to extinction ratio obtained from multi-angle LIDAR measurements will be used in this solution.

  14. Analysis and interpretation of lidar observations of the stratospheric aerosol

    NASA Technical Reports Server (NTRS)

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

    1980-01-01

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

  15. Initial Verification of GEOS-4 Aerosols Using CALIPSO and MODIS: Scene Classification

    NASA Technical Reports Server (NTRS)

    Welton, Ellsworth J.; Colarco, Peter R.; Hlavka, Dennis; Levy, Robert C.; Vaughan, Mark A.; daSilva, Arlindo

    2007-01-01

    A-train sensors such as MODIS and MISR provide column aerosol properties, and in the process a means of estimating aerosol type (e.g. smoke vs. dust). Correct classification of aerosol type is important because retrievals are often dependent upon selection of the right aerosol model. In addition, aerosol scene classification helps place the retrieved products in context for comparisons and analysis with aerosol transport models. The recent addition of CALIPSO to the A-train now provides a means of classifying aerosol distribution with altitude. CALIPSO level 1 products include profiles of attenuated backscatter at 532 and 1064 nm, and depolarization at 532 nm. Backscatter intensity, wavelength ratio, and depolarization provide information on the vertical profile of aerosol concentration, size, and shape. Thus similar estimates of aerosol type using MODIS or MISR are possible with CALIPSO, and the combination of data from all sensors provides a means of 3D aerosol scene classification. The NASA Goddard Earth Observing System general circulation model and data assimilation system (GEOS-4) provides global 3D aerosol mass for sulfate, sea salt, dust, and black and organic carbon. A GEOS-4 aerosol scene classification algorithm has been developed to provide estimates of aerosol mixtures along the flight track for NASA's Geoscience Laser Altimeter System (GLAS) satellite lidar. GLAS launched in 2003 and did not have the benefit of depolarization measurements or other sensors from the A-train. Aerosol typing from GLAS data alone was not possible, and the GEOS-4 aerosol classifier has been used to identify aerosol type and improve the retrieval of GLAS products. Here we compare 3D aerosol scene classification using CALIPSO and MODIS with the GEOS-4 aerosol classifier. Dust, smoke, and pollution examples will be discussed in the context of providing an initial verification of the 3D GEOS-4 aerosol products. Prior model verification has only been attempted with surface mass

  16. Statistical Characteristics of Aerosol Extinction Coefficient Profile in East Asia from CALIPSO

    NASA Astrophysics Data System (ADS)

    Sun, Xuejin; Zhou, Junhao; Zhou, Yongbo

    2016-06-01

    Aerosol extinction coefficient profile (ECP) is important in radiative transfer modeling, however, knowledge of ECP in some area has not been clearly recognized. To get a full understanding of statistical characteristics of ECP in three Asian regions: the Mongolian Plateau, the North China Plain and the Yellow Sea, CALIPSO aerosol product in 2012 is processed by conventional statistical methods. Orbit averaged ECP turns out to be mainly exponential and Gaussian patterns. Curve fitting shows that the two ECP patterns account for more than 50 percent of all the samples, especially in the Yellow Sea where the frequency of occurrence even reaches over 80 percent. Parameters determining fitting curves are provided consequently. To be specific, Gaussian pattern is the main ECP distribution in the Mongolian Plateau and the Yellow Sea, and exponential pattern predominates in the North China Plain. Besides, aerosol scale height reaches its maximum in summer and in the Mongolian Plateau. Meanwhile, the uplifting and deposition of dust during transportation are potentially explanations to the occurrence of Gaussian ECP. The results have certain representativeness, and contribute to reducing uncertainties of aerosol model in relevant researches.

  17. CALIOP near-real-time backscatter products compared to EARLINET data

    NASA Astrophysics Data System (ADS)

    Grigas, T.; Hervo, M.; Gimmestad, G.; Forrister, H.; Schneider, P.; Preißler, J.; Tarrason, L.; O'Dowd, C.

    2015-03-01

    The expedited near-real-time Level 1.5 Cloud-Aerosol Lidar (Light Detection and Ranging) with Orthogonal Polarization (CALIOP) products were evaluated against data from the ground-based European Aerosol Research Lidar Network (EARLINET). Over a period of three years, lidar data from 48 CALIOP overpasses with ground tracks within a 100 km distance from an operating EARLINET station were deemed suitable for analysis and they included a valid aerosol classification type (e.g. dust, polluted dust, clean marine, clean continental, polluted continental, mixed and/or smoke/biomass burning). For the complete dataset comprising both PBL and FT data, the correlation coefficient was 0.86, and when separated into separate layers, the PBL and FT correlation coefficients were 0.6 and 0.85 respectively. The presence of FT layers with high attenuated backscatter led to poor agreement in PBL backscatter profiles between the CALIOP and EARLINET measurements and prompted a further analysis filtering out such cases. However, the correlation coefficient value for the complete dataset decreased marginally from 0.86 to 0.84 while the PBL coefficient increased from 0.6 up to 0.65 and the FT coefficient also decreased from 0.85 to 0.79. For specific aerosol types, the correlation coefficient between CALIOP backscatter profiles and ground-based lidar data ranged from 0.37 for polluted continental aerosol in the planetary boundary layer (PBL) to 0.57 for dust in the free troposphere (FT). The results suggest different levels of agreement based on the location of the dominant aerosol layer and the aerosol type.

  18. Estimation of surface-level PM concentration from satellite observation taking into account the aerosol vertical profiles and hygroscopicity.

    PubMed

    Kim, Kwanchul; Lee, Kwon H; Kim, Ji I; Noh, Youngmin; Shin, Dong H; Shin, Sung K; Lee, Dasom; Kim, Jhoon; Kim, Young J; Song, Chul H

    2016-01-01

    Surface-level PM10 distribution was estimated from the satellite aerosol optical depth (AOD) products, taking the account of vertical profiles and hygroscopicity of aerosols over Jeju, Korea during March 2008 and October 2009. In this study, MODIS AOD data from the Terra and Aqua satellites were corrected with aerosol extinction profiles and relative humidity data. PBLH (Planetary Boundary Layer Height) was determined from MPLNET lidar-derived aerosol extinction coefficient profiles. Through statistical analysis, better agreement in correlation (R = 0.82) between the hourly PM10 concentration and hourly average Sunphotometer AOD was the obtained when vertical fraction method (VFM) considering Haze Layer Height (HLH) and hygroscopic growth factor f(RH) was used. The validity of the derived relationship between satellite AOD and surface PM10 concentration clearly demonstrates that satellite AOD data can be utilized for remote sensing of spatial distribution of regional PM10 concentration. PMID:26421659

  19. 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

  20. Vertical aerosol structure and aerosol mixed layer heights determined with scanning shipborne lidars during the TexAQS II study

    NASA Astrophysics Data System (ADS)

    McCarty, B. J.; Senff, C. J.; Tucker, S. C.; Eberhard, W. L.; Marchbanks, R. D.; Machol, J.; Brewer, W. A.

    2007-12-01

    The NOAA Earth Systems Research Laboratory (ESRL) deployed the Ozone Profiling Atmospheric LIDAR (OPAL) on the R/V Ronald H. Brown during the summer of 2006 for the Texas Air Quality Study (TEXAQS II). Calibrated aerosol backscatter profiles were determined from data collected at the 355 nm wavelength using a modified Klett retrieval method. OPAL employs a unique scan sequence that consists of staring at multiple elevation angles between 2 and 90 degrees, which is repeated approx. every 90 sec. Blending the data from the various elevation angles allows to extend the aerosol backscatter profiles down to near the surface (approximately 10 meters ASL), while maintaining a high spatial resolution (5 meters). Successful application of this technique requires the aerosol distribution to be sufficiently horizontally homogeneous over several kilometers. Estimates of aerosol mixed layer height were determined by applying a Haar wavelet transform method to detect the gradient that is often present at the top of the boundary layer. Co-located on the R/V Ronald H. Brown, was NOAA/ESRL's High Resolution Doppler LIDAR (HRDL). Aerosol mixed layer heights were also estimated using the data from the 2 micron Doppler LIDAR. A comparison of the mixed layer heights as determined from each LIDAR's observations was used to choose the height of the layer likely connected with the surface. The vertical structure of aerosols in the lower troposphere, in particular the presence of aerosol layers above the boundary layer, is important in understanding radiative effects of aerosols. We will present aerosol backscatter structure in the lower troposphere encountered during the TexAQS II study as well as a comparison of relative aerosol content in the free troposphere compared to that within the boundary layer.

  1. Coherent lidar technology for global wind profiling

    NASA Technical Reports Server (NTRS)

    Huffaker, R. M.

    1986-01-01

    Current lidar systems are proven sensors for atmospheric wind measurement. Ground-based and airborne continuous wave and pulsed CO2 systems were developed and applied to several wind measuring applications. Analytical and hardware feasibility studies indicte the feasibility of measuring the global wind field from a space splatform. A Global Backscater Experiment is planned by NASA to develop a global model of aerosol backscatter using a CO2 laser. Ground-based aerosol backscatter profiles will also be obtained using a ruby and a pulsed CO2 lidar.

  2. 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).

  3. A sensitivity study on the retrieval of aerosol vertical profiles using the oxygen A-band

    NASA Astrophysics Data System (ADS)

    Fedele Colosimo, Santo; Natraj, Vijay; Sander, Stanley P.; Stutz, Jochen

    2016-04-01

    Atmospheric absorption in the O2 A-band (12 950-13 200 cm-1) offers a unique opportunity to retrieve aerosol extinction profiles from space-borne measurements due to the large dynamic range of optical thickness in that spectral region. Absorptions in strong O2 lines are saturated; therefore, any radiance measured in these lines originates from scattering in the upper part of the atmosphere. Outside of O2 lines, or in weak lines, the atmospheric column absorption is small, and light penetrates to lower atmospheric layers, allowing for the quantification of aerosols and other scatterers near the surface.

    While the principle of aerosol profile retrieval using O2 A-band absorption from space is well-known, a thorough quantification of the information content, i.e., the amount of vertical profile information that can be obtained, and the dependence of the information content on the spectral resolution of the measurements, has not been thoroughly conducted. Here, we use the linearized vector radiative transfer model VLIDORT to perform spectrally resolved simulations of atmospheric radiation in the O2 A-band for four different aerosol extinction profile scenarios: urban (urban-rural areas), highly polluted (megacity areas with large aerosol extinction), elevated layer (identifying elevated plumes, for example for biomass burning) and low extinction (representative of small aerosol extinction, such as vegetated, marine and arctic areas). The high-resolution radiances emerging from the top of the atmosphere measurements are degraded to different spectral resolutions, simulating spectrometers with different resolving powers. We use optimal estimation theory to quantify the information content in the aerosol profile retrieval with respect to different aerosol parameters and instrument spectral resolutions. The simulations show that better spectral resolution generally leads to an increase in the total amount of information that can be retrieved, with the number of

  4. Altitude profile of aerosols on Mars from measurements of its thermal radiation on limb

    NASA Technical Reports Server (NTRS)

    Moroz, V. I.; Titov, D. V.; Gektin, Yu. M.; Naraeva, M. K.; Selivanov, A. S.

    1993-01-01

    Measurements of the thermal (range 7 - 13 micrometers) radiation of Mars with the high space resolution (approximately 2 km) were made by the TERMOSKAN experiment of the Phobos mission. Some of the results were published earlier but only the surface radiation was analyzed in detail. However some part of these measurements was made near the limb of the planet. The atmosphere gives an important input here in the planetary thermal radiation. Beyond the limb the atmosphere is the only source. The task of this work is to estimate some characteristics of the atmosphere using brightness profiles of the thermal radiation near the limb. An appropriate model of the temperature profile T(h) is necessary for such an analysis. A set of T(h) models (nominal, maximal and minimal) was defined using various sources including MARSGRAM, Viking-1 lander data, its theoretical considerations and boundary layer models. On the next step the possible input of the atmospheric gaseous emissions (wing of CO2 15 micrometer band) was estimated. It was found that even for the maximal T(h) this input is no more than a few percents of the measured radiation beyond the limb. Consequently the aerosols are responsible for almost all measured emission. The analysis of the observed profile showed that these aerosols have two components: (1) exponential with the scale height about 10 km and (2) some layered structure (two layers with maxima about 23 and 33 km consisted probably of ice).

  5. The GAW Aerosol Lidar Observation Network (GALION) as a source of near-real time aerosol profile data for model evaluation and assimilation

    NASA Astrophysics Data System (ADS)

    Hoff, R. M.; Pappalardo, G.

    2010-12-01

    In 2007, the WMO Global Atmospheric Watch’s Science Advisory Group on Aerosols described a global network of lidar networks called GAW Aerosol Lidar Observation Network (GALION). GALION has a purpose of providing expanded coverage of aerosol observations for climate and air quality use. Comprised of networks in Asia (AD-NET), Europe (EARLINET and CIS-LINET), North America (CREST and CORALNET), South America (ALINE) and with contribution from global networks such as MPLNET and NDACC, the collaboration provides a unique capability to define aerosol profiles in the vertical. GALION is designed to supplement existing ground-based and column profiling (AERONET, PHOTONS, SKYNET, GAWPFR) stations. In September 2010, GALION held its second workshop and one component of discussion focussed how the network would integrate into model needs. GALION partners have contributed to the Sand and Dust Storm Warning and Analysis System (SDS-WAS) and to assimilation in models such as DREAM. This paper will present the conclusions of those discussions and how these observations can fit into a global model analysis framework. Questions of availability, latency, and aerosol parameters that might be ingested into models will be discussed. An example of where EARLINET and GALION have contributed in near-real time observations was the suite of measurements during the Eyjafjallajokull eruption in Iceland and its impact on European air travel. Lessons learned from this experience will be discussed.

  6. The potential of LIRIC to validate the vertical profiles of the aerosol mass concentration estimated by an air quality model

    NASA Astrophysics Data System (ADS)

    Siomos, Nikolaos; Filoglou, Maria; Poupkou, Anastasia; Liora, Natalia; Dimopoulos, Spyros; Melas, Dimitris; Chaikovsky, Anatoli; Balis, Dimitris

    2015-04-01

    Vertical profiles of the aerosol mass concentration derived by a retrieval algorithm that uses combined sunphotometer and LIDAR data (LIRIC) were used in order to validate the mass concentration profiles estimated by the air quality model CAMx. LIDAR and CIMEL measurements of the Laboratory of Atmospheric Physics of the Aristotle University of Thessaloniki were used for this validation.The aerosol mass concentration profiles of the fine and coarse mode derived by CAMx were compared with the respective profiles derived by the retrieval algorithm. For the coarse mode particles, forecasts of the Saharan dust transportation model BSC-DREAM8bV2 were also taken into account. Each of the retrieval algorithm's profiles were matched to the models' profile with the best agreement within a time window of four hours before and after the central measurement. OPAC, a software than can provide optical properties of aerosol mixtures, was also employed in order to calculate the angstrom exponent and the lidar ratio values for 355nm and 532nm for each of the model's profiles aiming in a comparison with the angstrom exponent and the lidar ratio values derived by the retrieval algorithm for each measurement. The comparisons between the fine mode aerosol concentration profiles resulted in a good agreement between CAMx and the retrieval algorithm, with the vertical mean bias error never exceeding 7 μgr/m3. Concerning the aerosol coarse mode concentration profiles both CAMx and BSC-DREAM8bV2 values are severely underestimated, although, in cases of Saharan dust transportation events there is an agreement between the profiles of BSC-DREAM8bV2 model and the retrieval algorithm.

  7. Vertical Profiles of Aerosol Particle Sizes using MGS/TES and MRO/MCS

    NASA Astrophysics Data System (ADS)

    Wolff, M. J.; Clancy, R. T.; Smith, M. D.; Benson, J. L.; McConnochie, T. H.; Pankine, A.

    2012-12-01

    Vertical variations in aerosol particle sizes often have a dramatic impact on the state and evolution of the Martian atmosphere. Recent analyses of data from the Spectroscopy for the Investigation of the Characteristics of the Atmosphere of Mars (SPICAM), the Thermal Emission Spectrometer (TES), and the Mars Climate Sounder (MCS) instruments offer some long overdue progress in constraining this aspect of aerosols. However, significantly more work remains to be done along these lines in order to better constrain and inform modern dynamical simulations of the Martian atmosphere. Thus, the primary goal of our work is to perform retrievals of particle size as a function of altitude for both dust and water ice aerosols. The choice of the TES and MCS dataset, with pole-to-pole coverage over a period of nearly eight martian years, provides the crucial systematic temporal and spatial sampling. Our presentation will include: 1) A summary of our limb radiative transfer algorithms and retrieval schemes; 2) The initial results of the application of our particle size retrieval scheme to the 2001 TES and 2007 MCS observations of those planet encircling dust events; 3) Near-term plans for for additional retrievals (aphelion cloud season, lower optical depth locations and seasons, etc.); 4) Location of the archive to be used for the distribution of the derived profiles and associated retrieval metadata.

  8. CALIOP near-real-time backscatter products compared to EARLINET data

    NASA Astrophysics Data System (ADS)

    Grigas, T.; Hervo, M.; Gimmestad, G.; Forrister, H.; Schneider, P.; Preißler, J.; Tarrason, L.; O'Dowd, C.

    2015-11-01

    The expedited near-real-time Level 1.5 Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) version 3 products were evaluated against data from the ground-based European Aerosol Research Lidar Network (EARLINET). The statistical framework and results of the three-year evaluation of 48 CALIOP overpasses with ground tracks within a 100 km distance from operating EARLINET stations are presented and include analysis for the following CALIOP classifications of aerosol type: dust, polluted dust, clean marine, clean continental, polluted continental, mixed and/or smoke/biomass burning. For the complete data set comprising both the planetary boundary layer (PBL) and the free troposphere (FT) data, the correlation coefficient (R) was 0.86. When the analysis was conducted separately for the PBL and FT, the correlation coefficients were R = 0.6 and R = 0.85, respectively. From analysis of selected specific cases, it was initially thought that the presence of FT layers, with high attenuated backscatter, led to poor agreement of the PBL backscatter profiles between the CALIOP and EARLINET and prompted a further analysis to filter out such cases; however, removal of these layers did not improve the agreement as R reduced marginally from R = 0.86 to R = 0.84 for the combined PBL and FT analysis, increased marginally from R = 0.6 up to R = 0.65 for the PBL on its own, and decreased marginally from R = 0.85 to R = 0.79 for the FT analysis on its own. This suggests considerable variability, across the data set, in the spatial distribution of the aerosol over spatial scales of 100 km or less around some EARLINET stations rather than influence from elevated FT layers. For specific aerosol types, the correlation coefficient between CALIOP backscatter profiles and the EARLINET data ranged from R = 0.37 for polluted continental aerosol in the PBL to R = 0.57 for dust in the FT.

  9. Vertical profiles of aerosol optical properties and the solar heating rate estimated by combining sky radiometer and lidar measurements

    NASA Astrophysics Data System (ADS)

    Kudo, Rei; Nishizawa, Tomoaki; Aoyagi, Toshinori

    2016-07-01

    The SKYLIDAR algorithm was developed to estimate vertical profiles of aerosol optical properties from sky radiometer (SKYNET) and lidar (AD-Net) measurements. The solar heating rate was also estimated from the SKYLIDAR retrievals. The algorithm consists of two retrieval steps: (1) columnar properties are retrieved from the sky radiometer measurements and the vertically mean depolarization ratio obtained from the lidar measurements and (2) vertical profiles are retrieved from the lidar measurements and the results of the first step. The derived parameters are the vertical profiles of the size distribution, refractive index (real and imaginary parts), extinction coefficient, single-scattering albedo, and asymmetry factor. Sensitivity tests were conducted by applying the SKYLIDAR algorithm to the simulated sky radiometer and lidar data for vertical profiles of three different aerosols, continental average, transported dust, and pollution aerosols. The vertical profiles of the size distribution, extinction coefficient, and asymmetry factor were well estimated in all cases. The vertical profiles of the refractive index and single-scattering albedo of transported dust, but not those of transported pollution aerosol, were well estimated. To demonstrate the performance and validity of the SKYLIDAR algorithm, we applied the SKYLIDAR algorithm to the actual measurements at Tsukuba, Japan. The detailed vertical structures of the aerosol optical properties and solar heating rate of transported dust and smoke were investigated. Examination of the relationship between the solar heating rate and the aerosol optical properties showed that the vertical profile of the asymmetry factor played an important role in creating vertical variation in the solar heating rate. We then compared the columnar optical properties retrieved with the SKYLIDAR algorithm to those produced with the more established scheme SKYRAD.PACK, and the surface solar irradiance calculated from the SKYLIDAR

  10. Relating Aerosol Profile and Column Measurements to Surface Concentrations: What Have We Learned from Discover-AQ?

    NASA Astrophysics Data System (ADS)

    Hoff, R. M.

    2014-12-01

    One research goal of the Deriving Information on Surface Conditions from COlumn and VERtically Resolved Observations Relevant to Air Quality (DISCOVER-AQ) mission was to determine sufficient column profile measurements to relate column integrated quantities such as Aerosol Optical Depth to surface concentrations. I will review the relationship between AOD and PM2.5 at the surface. DISCOVER-AQ in Baltimore, the San Joaquin Valley, Houston and Denver revealed quite different conditions for determining this relationship. In each case, the surface reflectivity made determination of aerosol optical depth challenging, but upward looking columns of aerosol optical depth from sunphotometers provided confirmation of the AOD results from space. In Baltimore, AOD fields reflected PM2.5 concentrations well. In California, however, the low boundary layer heights and dominance of nitrate and organic aerosols made the AOD fields less predictive of PM2.5. In California and Colorado, hydration of the aerosol varied dramatically with aerosol type (especially smoke and dust) and revealed that without an understanding of the degree of aerosol hydration with aerosol composition, the relationship between AOD and PM2.5 will continue to be a challenge. Model predictions in the Baltimore-Washington study are relatively disappointing in helping define the needed physics between the optical and microphysical properties. An overview of the measurements from DISCOVER-AQ which will help define the needed information in a more general case in the future will be given.

  11. Retrieving the Vertical Structure of the Effective Aerosol Complex Index of Refraction from a Combination of Aerosol in Situ and Remote Sensing Measurements During TARFOX

    NASA Technical Reports Server (NTRS)

    Redemann, J.; Turco, R. P.; Liou, K. N.; Russell, P. B.; Bergstrom, R. W.; Schmid, B.; Livingston, J. M.; Hobbs, P. V.; Hartley, W. S.; Ismail, S.; Ferrare, R. A.; Browell, E. V.

    2000-01-01

    The largest uncertainty in estimates of the effects of atmospheric aerosols on climate stems from uncertainties in the determination of their microphysical properties, including the aerosol complex index of refraction, which in turn determines their optical properties. A novel technique is used to estimate the aerosol complex index of refraction in distinct vertical layers from a combination of aerosol in situ size distribution and remote sensing measurements during the Tropospheric Aerosol Radiative Forcing Observational Experiment (TARFOX). In particular, aerosol backscatter measurements using the NASA Langley LASE (Lidar Atmospheric Sensing Experiment) instrument and in situ aerosol size distribution data are utilized to derive vertical profiles of the "effective" aerosol complex index of refraction at 815 nm (i.e., the refractive index that would provide the same backscatter signal in a forward calculation on the basis of the measured in situ particle size distributions for homogeneous, spherical aerosols). A sensitivity study shows that this method yields small errors in the retrieved aerosol refractive indices, provided the errors in the lidar-derived aerosol backscatter are less than 30% and random in nature. Absolute errors in the estimated aerosol refractive indices are generally less than 0.04 for the real part and can be as much as 0.042 for the imaginary part in the case of a 30% error in the lidar-derived aerosol backscatter. The measurements of aerosol optical depth from the NASA Ames Airborne Tracking Sunphotometer (AATS-6) are successfully incorporated into the new technique and help constrain the retrieved aerosol refractive indices. An application of the technique to two TARFOX case studies yields the occurrence of vertical layers of distinct aerosol refractive indices. Values of the estimated complex aerosol refractive index range from 1.33 to 1.45 for the real part and 0.001 to 0.008 for the imaginary part. The methodology devised in this study

  12. 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

  13. Turn-key Raman lidar for profiling atmospheric water vapor, clouds, and aerosols.

    PubMed

    Goldsmith, J E; Blair, F H; Bisson, S E; Turner, D D

    1998-07-20

    We describe an operational, self-contained, fully autonomous Raman lidar system that has been developed for unattended, around-the-clock atmospheric profiling of water vapor, aerosols, and clouds. During a 1996 three-week intensive observational period, the system operated during all periods of good weather (339 out of 504 h), including one continuous five-day period. The system is based on a dual-field-of-view design that provides excellent daytime capability without sacrificing nighttime performance. It is fully computer automated and runs unattended following a simple, brief (~5-min) start-up period. We discuss the theory and design of the system and present detailed analyses of the derivation of water-vapor profiles from the lidar measurements. PMID:18285967

  14. Retrieving the Vertical Structure of the Effective Aerosol Complex Index of Refraction from a Combination of Aerosol in Situ and Remote Sensing Measurements During TARFOX

    NASA Technical Reports Server (NTRS)

    Redemann, J.; Turco, R. P.; Liou, K. N.; Russell, P. B.; Bergstrom, R. W.; Schmid, B.; Livingston, J. M.; Hobbs, P. V.; Hartley, W. S.; Ismail, S.

    2000-01-01

    The largest uncertainty in estimates of the effects of atmospheric aerosols on climate stems from uncertainties in the determination of their microphysical properties, including the aerosol complex index of refraction, which in turn determines their optical properties. A novel technique is used to estimate the aerosol complex index of refraction in distinct vertical layers from a combination of aerosol in situ size distribution and remote sensing measurements during the Tropospheric Aerosol Radiative Forcing Observational Experiment (TARFOX). In particular, aerosol backscatter measurements using the NASA Langley LASE (Lidar Atmospheric Sensing Experiment) instrument and in situ aerosol size distribution data are utilized to derive vertical profiles of the 'effective' aerosol complex index of refraction at 815 nm (i.e., the refractive index that would provide the same backscatter signal in a forward calculation on the basis of the measured in situ particle size distributions for homogeneous, spherical aerosols). A sensitivity study shows that this method yields small errors in the retrieved aerosol refractive indices, provided the errors in the lidar derived aerosol backscatter are less than 30% and random in nature. Absolute errors in the estimated aerosol refractive indices are generally less than 0.04 for the real part and can be as much as 0.042 for the imaginary part in the case of a 30% error in the lidar-derived aerosol backscatter. The measurements of aerosol optical depth from the NASA Ames Airborne Tracking Sunphotometer (AATS-6) are successfully incorporated into the new technique and help constrain the retrieved aerosol refractive indices. An application of the technique to two TARFOX case studies yields the occurrence of vertical layers of distinct aerosol refractive indices. Values of the estimated complex aerosol refractive index range from 1.33 to 1.45 for the real part and 0.001 to 0.008 for the imaginary part. The methodology devised in this study

  15. Influence of the vertical absorption profile of mixed Asian dust plumes on aerosol direct radiative forcing over East Asia

    NASA Astrophysics Data System (ADS)

    Noh, Young Min; Lee, Kwonho; Kim, Kwanchul; Shin, Sung-Kyun; Müller, Detlef; Shin, Dong Ho

    2016-08-01

    We estimate the aerosol direct radiative forcing (ADRF) and heating rate profiles of mixed East Asian dust plumes in the solar wavelength region ranging from 0.25 to 4.0 μm using the Santa Barbara Discrete Ordinate Atmospheric Radiative Transfer (SBDART) code. Vertical profiles of aerosol extinction coefficients and single-scattering albedos (SSA) were derived from measurements with a multi-wavelength Raman lidar system. The data are used as input parameters for our radiative transfer calculations. We considered four cases of radiative forcing in SBDART: 1. dust, 2. pollution, 3. mixed dust plume and the use of vertical profiles of SSA, and 4. mixed dust plumes and the use of column-averaged values of SSA. In our sensitivity study we examined the influence of SSA and aerosol layer height on our results. The ADRF at the surface and in the atmosphere shows a small dependence on the specific shape of the aerosol extinction vertical profile and its light-absorption property for all four cases. In contrast, at the top of the atmosphere (TOA), the ADRF is largely affected by the vertical distribution of the aerosols extinction. This effect increases if the light-absorption capacity (decrease of SSA) of the aerosols increases. We find different radiative effects in situations in which two layers of aerosols had different light-absorption properties. The largest difference was observed at the TOA for an absorbing aerosol layer at high altitude in which we considered in one case the vertical profile of SSA and in another case the column-averaged SSA only. The ADRF at the TOA increases when the light-absorbing aerosol layer is located above 3 km altitude. The differences between height-resolved SSA, which can be obtained from lidar data, and total layer-mean SSA indicates that the use of a layer-mean SSA can be rather misleading as it can induce a large error in the calculation of the ADRF at the TOA, which in turn may cause errors in the vertical profiles of heating rates.

  16. Wavelength dependent near-range lidar profiling of smog aerosol over Athens

    NASA Astrophysics Data System (ADS)

    Stachlewska, Iwona S.; Marinou, Eleni; Engelmann, Ronny; Costa Surós, Montserrat; Kottas, Mickael; Baars, Holger; Janicka, Lucja; Solomos, Stavros; Heese, Birgit; Kumala, Wojciech; Tsekeri, Alexandra; Binietoglou, Ioannis; Markowicz, Krzysztof M.; Amiridis, Vassilis; Balis, Dimitris; Althausen, Dietrich; Wandinger, Ulla; Ansmann, Albert

    2016-04-01

    Recently, the ACTRIS2 JRA1 field campaign focusing on joint remote and in-situ sensing of absorbing aerosols has been conducted in Athens (http://actris-athens.eu). In the frame of the ACTRIS2 BL-Smog TNA, co-located measurements of the near-range lidar receiver (NARLa) of the University of Warsaw with the multi-wavelength PollyXT lidar of the National Observatory of Athens were performed. The excellent capacities of the PollyXT-NOA lidar, equipped with eight far-range channels (355, 355s, 387, 407, 532, 532s, 607, and 1064nm) and two near-range channels (532 and 607 nm), were enhanced by integrating the NARLa for simultaneous observations. By using the NARLa, equipped with the elastic channels (355 and 532nm) and Raman channels (387 and 607nm), the wavelength dependence of the aerosol particles properties within boundary layer was captured. The dominant conditions observed during the JRA1 period were the fresh winter smog layers occurring in lowermost boundary layer over Athens. NARLa provided profiles as close to surface as 50m, thus the data obtained in the near-range were used for the incomplete overlap region of the far-field channels. With NARLa we assessed the overlap at 355 and 532nm wavelengths and concluded on the possibility of using the single near-range 532 nm channel for the overlap correction in both VIS and UV channels of the PollyXT-NOA. As a result, the obtained lidar profiles are expected to be more consistent with the sunphotometer measurements. In the future, the GARRLiC code can be applied on the synergy of combined near and far range lidar profiles with AERONET data sets in order to study improvement on the inversion results.

  17. TOMS Validation Based on Profiles of Aerosol Properties in the Lower Troposphere as Obtained with Light Aircraft Systems

    NASA Technical Reports Server (NTRS)

    Prospero, Joseph M.; Maring, Hal; Savoie, Dennis

    2003-01-01

    The goal of the University of Miami Aerosol Group (UMAG) in this project was to make measurements of vertical profiles of aerosol properties and aerosol optical depth using a light aircraft. The UMAG developed a light aircraft aerosol package (LAAP) that was used in light aircraft (Cessna 172) during the Puerto Rico Dust Experiment (PRIDE). This field campaign took place on Puerto Rico during July 2000. Design details and results from the use of the LAAP were presented at TOMS Science team meetings on April 1998, April 1999, and May 2000. Results from the LAAP collected during the PRIDE Experiment were presented at the Fall Meeting of the American Geophysical Union, December 2000. Some of the results from the LAAP collected during the PRIDE Experiment have been accepted for publication in the Journal of Geophysical Research in a "topical section" made up of papers from the PRIDE Program.

  18. Vertical profiling of aerosol hygroscopic properties in the planetary boundary layer during the PEGASOS campaigns

    NASA Astrophysics Data System (ADS)

    Rosati, B.; Gysel, M.; Rubach, F.; Mentel, T. F.; Goger, B.; Poulain, L.; Schlag, P.; Miettinen, P.; Pajunoja, A.; Virtanen, A.; Bialek, J.; Klein Baltink, H.; Henzing, J. S.; Größ, J.; Gobbi, G. P.; Wiedensohler, A.; Kiendler-Scharr, A.; O'Dowd, C.; Decesari, S.; Facchini, M. C.; Weingartner, E.; Baltensperger, U.

    2015-03-01

    Airborne measurements of the aerosol hygroscopic and optical properties as well as chemical composition were performed in the Netherlands and northern Italy on board of a Zeppelin NT airship during the PEGASOS field campaigns in 2012. The vertical changes in aerosol properties during the development of the mixing layer were studied. Hygroscopic growth factors (GF) at 95% relative humidity were determined using the white-light humidified optical particles spectrometer (WHOPS) for dry diameters of 300 and 500 nm particles. These measurements were supplemented by an aerosol mass spectrometer (AMS) and an aethalometer providing information on the aerosol chemical composition. Several vertical profiles between 100 and 700 m a.g. were flown just after sunrise close to the San Pietro Capofiume ground station in the Po Valley, Italy. During the early morning hours the lowest layer (newly developing mixing layer) contained a high nitrate fraction (20%) which was coupled with enhanced hygroscopic growth. In the layer above (residual layer) small nitrate fractions of ~ 2% were measured as well as low GFs. After full mixing of the layers, typically around noon and with increased temperature, the nitrate fraction decreased to 2% at all altitudes and led to similar hygroscopicity values as found in the residual layer. These distinct vertical and temporal changes underline the importance of airborne campaigns to study aerosol properties during the development of the mixed layer. The aerosol was externally mixed with 22 and 67% of the 500 nm particles in the range GF < 1.1 and GF > 1.5, respectively. Contributors to the non-hygroscopic mode in the observed size range are most likely mineral dust and biological material. Mean hygroscopicity parameters (κ) were 0.34, 0.19 and 0.18 for particles in the newly forming mixing layer, residual layer and fully mixed layer, respectively. These results agree well with those from chemical analysis which found values of κ = 0.27, 0.21 and 0

  19. 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.

  20. Inter-comparison of CALIPSO and CloudSat retrieved profiles of aerosol and cloud microphysical parameters with aircraft profiles over a tropical region

    NASA Astrophysics Data System (ADS)

    Padmakumari, B.; Harikishan, G.; Maheskumar, R. S.

    2016-05-01

    Satellites play a major role in understanding the spatial and vertical distribution of aerosols and cloud microphysical parameters over a large area. However, the inherent limitations in satellite retrievals can be improved through inter-comparisons with airborne platforms. Over the Indian sub-continent, the vertical profiles retrieved from space-borne lidar such as CALIOP (Cloud-Aerosol LIdar with Orthogonal Polarization) on board the satellite CALIPSO and Cloud Profiling Radar (CPR) on board the satellite CloudSat were inter- compared with the aircraft observations conducted during Cloud Aerosol Interactions and Precipitation Enhancement Experiment (CAIPEEX). In the absence of high clouds, both aircraft and CALIOP showed similar features of aerosol layering and water-ice cloud signatures. As CALIOP could not penetrate the thick clouds, the aerosol information below the cloud is missed. While the aircraft could measure high concentrations below the cloud base and above the low clouds in the presence of high clouds. The aircraft derived liquid water content (LWC) and droplet effective radii (Re) showed steady increase from cloud base to cloud top with a variable cloud droplet number concentration (CDNC). While the CloudSat derived LWC, CDNC and Re showed increase from the cloud top to cloud base in contradiction to the aircraft measurements. The CloudSat profiles are underestimated as compared to the corresponding aircraft profiles. Validation of satellite retrieved vertical profiles with aircraft measurements is very much essential over the tropics to improve the retrieval algorithms and to constrain the uncertainties in the regional cloud parameterization schemes.

  1. Light Scattering by Aerosols Over the Remote Ocean: Clear-Sky Point and Column Radiative Closure Studies

    NASA Astrophysics Data System (ADS)

    Fridlind, A. M.; Jacobson, M. Z.

    2001-12-01

    Field data gathered by ship and aircraft during leg 2 of the First Aerosol Characterization Experiment (ACE 1) were used to study clear-sky radiative closure over the remote Southern Ocean. Closure was evaluated by comparing observations with modeled values of: (i) aerosol light scattering coefficients in the marine boundary layer and free troposphere, (ii) total aerosol optical depth, and (iii) total solar radiation at the ocean surface. Point modeling using the ship data benefited from an existing study of closure on the ship, expanding the number of data points considered in that study from 22 to 887. Point and column modeling using the aircraft data provide the first such studies to date. Aerosol light scattering coefficients were calculated from size-distributed measurements of aerosol chemical composition and number concentration, and were compared with observations at three wavelengths (450, 550, and 700 nm) on both ship and aircraft. Point closure on the ship could be achieved at all wavelengths for both total and hemispheric backscattering coefficients if the model accounted for experimental uncertainties in aerosol chemistry, nephelometer nonidealities, and the likely nonsphericity of dried sea salt aerosols. Point closure on the aircraft could be achieved at most wavelengths for total scattering coefficients, but could not be achieved at any wavelengths for hemispheric backscattering coefficients. Deviations between predicted and observed backscattering coefficients on the aircraft were widely scattered rather than biased, indicating that a low signal to noise ratio in observed backscattering coefficients was the likely cause for lack of closure. Aerosol optical depth and solar radiation at the ocean surface were calculated for the two days with clear-sky periods when the aircraft measured aerosol profiles near the ship. Input gas and meteorological data were the observed profiles of ozone, water vapor, temperature, and pressure from the surface to

  2. Vertical profiling of aerosol particles and trace gases over the central Arctic Ocean during summer

    NASA Astrophysics Data System (ADS)

    Kupiszewski, P.; Leck, C.; Tjernström, M.; Sjogren, S.; Sedlar, J.; Graus, M.; Müller, M.; Brooks, B.; Swietlicki, E.; Norris, S.; Hansel, A.

    2013-12-01

    Unique measurements of vertical size-resolved aerosol particle concentrations, trace gas concentrations and meteorological data were obtained during the Arctic Summer Cloud Ocean Study (ASCOS, www.ascos.se), an International Polar Year project aimed at establishing the processes responsible for formation and evolution of low-level clouds over the high Arctic summer pack ice. The experiment was conducted from on board the Swedish icebreaker Oden, and provided both ship- and helicopter-based measurements. This study focuses on the vertical helicopter profiles and onboard measurements obtained during a three-week period when Oden was anchored to a drifting ice floe, and sheds light on the characteristics of Arctic aerosol particles and their distribution throughout the lower atmosphere. Distinct differences in aerosol particle characteristics within defined atmospheric layers are identified. Within the lowermost couple hundred metres, transport from the marginal ice zone (MIZ), condensational growth and cloud processing develop the aerosol population. During two of the four representative periods defined in this study, such influence is shown. At altitudes above about 1 km, long-range transport occurs frequently. However, only infrequently does large-scale subsidence descend such air masses to become entrained into the mixed layer in the high Arctic, and therefore long-range transport plumes are unlikely to directly influence low-level stratiform cloud formation. Nonetheless, such plumes can influence the radiative balance of the planetary boundary layer (PBL) by influencing formation and evolution of higher clouds, as well as through precipitation transport of particles downwards. New particle formation was occasionally observed, particularly in the near-surface layer. We hypothesize that the origin of these ultrafine particles could be in biological processes, both primary and secondary, within the open leads between

  3. Vertical profiling of aerosol particles and trace gases over the central Arctic Ocean during summer

    NASA Astrophysics Data System (ADS)

    Kupiszewski, P.; Leck, C.; Tjernström, M.; Sjogren, S.; Sedlar, J.; Graus, M.; Müller, M.; Brooks, B.; Swietlicki, E.; Norris, S.; Hansel, A.

    2013-04-01

    Unique measurements of vertical size resolved aerosol particle concentrations, trace gas concentrations and meteorological data were obtained during the Arctic Summer Cloud Ocean Study (ASCOS, http://www.ascos.se), an International Polar Year project aimed at establishing the processes responsible for formation and evolution of low-level clouds over the high Arctic summer pack ice. The experiment was conducted from onboard the Swedish icebreaker Oden, and provided both ship- and helicopter-based measurements. This study focuses on the vertical helicopter profiles and onboard measurements obtained during a three-week period when Oden was anchored to a drifting ice floe, and sheds light on the characteristics of Arctic aerosol particles and their distribution throughout the lower atmosphere. Distinct differences in aerosol particle characteristics within defined atmospheric layers are identified. Near the surface (lowermost couple hundred meters), transport from the marginal ice zone (MIZ), if sufficiently short (less than ca. 2 days), condensational growth and cloud-processing develop the aerosol population. During two of the four representative periods defined in this study, such influence is shown. At altitudes above about 1 km, long-range transport occurs frequently. However, only infrequently does large-scale subsidence descend such air masses to become entrained into the mixed layer in the high Arctic, and therefore they are unlikely to directly influence low-level stratiform cloud formation. Nonetheless, long-range transport plumes can influence the radiative balance of the PBL by influencing formation and evolution of higher clouds, as well as through precipitation transport of particles downwards. New particle formation was occasionally observed, particularly in the near-surface layer. We hypothesize that the origin of these ultrafine particles can be from biological processes, both primary and secondary

  4. 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

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-11-01

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

  7. SAGE II aerosol data validation based on retrieved aerosol model size distribution from SAGE II aerosol measurements.

    PubMed

    Wang, P H; 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; Hofmann, D J; Grams, G W; Fuller, W H; Yue, G K

    1989-06-20

    This paper describes an investigation of the comprehensive aerosol correlative measurement experiments conducted between November 1984 and July 1986 for satellite measurement program of the Stratospheric Aerosol and Gas Experiment (SAGE II). The correlative sensors involved in the experiments consist of the NASA Ames Research Center impactor/laser probe, the University of Wyoming dustsonde, and the NASA Langley Research Center airborne 14-inch (36 cm) lidar system. The approach of the analysis is to compare the primary aerosol quantities measured by the ground-based instruments with the calculated ones based on the aerosol size distributions retrieved from the SAGE II aerosol extinction measurements. The analysis shows that the aerosol size distributions derived from the SAGE II observations agree qualitatively with the in situ measurements made by the impactor/laser probe. The SAGE II-derived vertical distributions of the ratio N0.15/N0.25 (where Nr is the cumulative aerosol concentration for particle radii greater than r, in micrometers) and the aerosol backscatter profiles at 0.532- and 0.6943-micrometer lidar wavelengths are shown to agree with the dustsonde and the 14-inch (36-cm) lidar observations, with the differences being within the respective uncertainties of the SAGE II and the other instruments. PMID:11539801

  8. Biogenic VOC oxidation and organic aerosol formation in an urban nocturnal boundary layer: aircraft vertical profiles in Houston, TX

    NASA Astrophysics Data System (ADS)

    Brown, S. S.; Dubé, W. P.; Bahreini, R.; Middlebrook, A. M.; Brock, C. A.; Warneke, C.; de Gouw, J. A.; Washenfelder, R. A.; Atlas, E.; Peischl, J.; Ryerson, T. B.; Holloway, J. S.; Schwarz, J. P.; Spackman, R.; Trainer, M.; Parrish, D. D.; Fehshenfeld, F. C.; Ravishankara, A. R.

    2013-11-01

    Organic compounds are a large component of aerosol mass, but organic aerosol (OA) sources remain poorly characterized. Recent model studies have suggested nighttime oxidation of biogenic hydrocarbons as a potentially large OA source, but analysis of field measurements to test these predictions is sparse. We present nighttime vertical profiles of nitrogen oxides, ozone, VOCs and aerosol composition measured during low approaches of the NOAA P-3 aircraft to airfields in Houston, TX. This region has large emissions of both biogenic hydrocarbons and nitrogen oxides. The latter category serves as a source of the nitrate radical, NO3, a key nighttime oxidant. Biogenic VOCs (BVOC) and urban pollutants were concentrated within the nocturnal boundary layer (NBL), which varied in depth from 100-400 m. Despite concentrated NOx at low altitude, ozone was never titrated to zero, resulting in rapid NO3 radical production rates of 0.2-2.7 ppbv h-1 within the NBL. Monoterpenes and isoprene were frequently present within the NBL and underwent rapid oxidation (up to 1 ppbv h-1), mainly by NO3 and to a lesser extent O3. Concurrent enhancement in organic and nitrate aerosol on several profiles was consistent with primary emissions and with secondary production from nighttime BVOC oxidation, with the latter equivalent to or slightly larger than the former. Some profiles may have been influenced by biomass burning sources as well, making quantitative attribution of organic aerosol sources difficult. Ratios of organic aerosol to CO within the NBL ranged from 14 to 38 μg m-3 OA/ppmv CO. A box model simulation incorporating monoterpene emissions, oxidant formation rates and monoterpene SOA yields suggested overnight OA production of 0.5 to 9 μg m-3.

  9. Simulated lidar return from a one-dimensional stratospheric aerosol model

    NASA Technical Reports Server (NTRS)

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

    1979-01-01

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

  10. Analyses of scattering characteristics of chosen anthropogenic aerosols

    NASA Astrophysics Data System (ADS)

    Kaszczuk, Miroslawa; Mierczyk, Zygmunt; Muzal, Michal

    2008-10-01

    In the work, analyses of scattering profile of chosen anthropogenic aerosols for two wavelengths (λ1 = 1064 nm and λ2 = 532 nm) were made. As an example of anthropogenic aerosol three different pyrotechnic mixtures (DM11, M2, M16) were taken. Main parameters of smoke particles were firstly analyzed and well described, taking particle shape and size into special consideration. Shape of particles was analyzed on the basis of SEM pictures, and particle size was measured. Participation of particles in each fixed fraction characterized by range of sizes was analyzed and parameters of smoke particles of characteristic sizes and function describing aerosol size distribution (ASD) were determinated. Analyses of scattering profiles were carried out on the basis of both model of scattering on spherical and nonspherical particles. In the case of spherical particles Rayleigh-Mie model was used and for nonspherical particles analyses firstly model of spheroids was used, and then Rayleigh-Mie one. For each characteristic particle one calculated value of four parameters (effective scattering cross section σSCA, effective backscattering cross section σBSCA, scattering efficiency QSCA, backscattering efficiency QBSCA) and value of backscattering coefficient β for whole particles population. Obtained results were compared with the same parameters calculated for natural aerosol (cirrus cloud).

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

    DOE PAGESBeta

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

    2016-01-18

    In this study, 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 ~2km. Doubling the calculated aerosol extinctions below 850 hPa generates much better agreement with the observed AOD andmore » 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

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

    NASA Astrophysics Data System (ADS)

    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 respond differently

  13. 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

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

    DOE PAGESBeta

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

    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

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

    DOE PAGESBeta

    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 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

  16. 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

  17. In situ vertical profiles of aerosol extinction, mass, and composition over the SEUS during the SENEX and SEAC4RS studies

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    Shallow cumulus convection enhances vertical transport of trace gases and aerosol and creates a cloudy transition layer on top of the sub-cloud mixed layer. Two recent studies have proposed that an elevated layer of enhanced organic aerosol over the southeastern United States (SEUS) could explain the discrepancy in the summertime enhancement of aerosol optical depth (AOD) and summertime enhancement of surface measurements of aerosol mass. We investigate the vertical profile of aerosol over the SEUS during the summertime using in situ aircraft-based measurements of aerosol from the SENEX and SEAC4RS studies. During shallow cumulus convection over the SEUS, we found that aerosol and trace gas concentration in the transition layer are diluted by cleaner air from the free troposphere, and the absolute aerosol loading decreases with altitude in the transition layer. However, after normalizing the vertical profiles to the CO boundary layer enhancement to correct for the dilution, the aerosol mass, volume, and extinction relative to the boundary layer CO enhancement is ~20% greater in the transition layer than in the mixed layer. The enhancement of aerosol loading suggests production of aerosol mass in the transition layer, although biomass burning could also be the source of the enhancement. The median composition of the aerosol in the mixed layer is ~70% organics and ~18% sulfate, while it is 65% organics and 23% sulfate in the transition layer. The composition of the aerosol enhancement in the transition layer is roughly equal parts sulfate and organics by mass. The enhancement of aerosol extinction in the transition layer is not sufficient to explain the summertime enhancement of AOD over SEUS.

  18. 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.

  19. 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

  20. An Investigation of Dust Aerosols and Atmospheric Profiles Associated with North Atlantic Hurricanes Using Multi-Sensor Measurements

    NASA Astrophysics Data System (ADS)

    Kamal, Mohammed Mostafa

    MODerate resolution Imaging Spectroradiometer (MODIS) Aerosol Optical Thickness (AOT) and the Atmospheric Infrared Sounder (AIRS) atmospheric profiles (temperature and moisture) Level 2 products are studied to investigate dust aerosol impacts on hurricanes through spatial analysis for four hurricanes Isabel (2003), Frances (2004), Katrina (2005) and Helene (2006). Spatial regions were selected based on two concentric circles (an annulus) and segmented by left and right regions of 180° each around the hurricane's eye. Statistical relationships between MODIS AOT, AIRS temperature and percent relative humidity (RH) among these four hurricanes is presented. The variation of temperature and RH values represented in static-left, static-right, dynamic-left and dynamic-right for the 500 mb, 700 mb and 850 mb pressure levels were analyzed to determine the impacts of dust aerosols on temperature and RH. For the four hurricanes' average, AOT was found highest in Helene as opposed to (0.27) Isabel (0.23), Frances (0.18) and Katrina (0.16). Dust aerosols showed negative impacts on the atmospheric moisture levels and positive on the temperature. Additionally, a systematic multivariate analysis of MODIS aerosol retrievals over the North Atlantic spanning 7 hurricane seasons combined with Statistical Hurricane Intensity Prediction Scheme (SHIPS) parameters is presented. My focus is on investigating the effects of 5 categories that include aerosol, wind, relative humidity, shear, and temperature on hurricane intensities. The primary goal is to be able to explain the same physical phenomena equally well by significantly reducing the number of parameters employed in the statistical analysis. Five categories which include, wind, aerosol, shear, relative humidity, and temperature components were established by reducing 56 variables to 20. Aerosol, wind, humidity, shear, and temperature were all contributing factors in the regression equation with the ranking for the contribution found

  1. Sensitivity Analysis on Fu-Liou-Gu Radiative Transfer Model for different lidar aerosol and cloud profiles

    NASA Astrophysics Data System (ADS)

    Lolli, Simone; Madonna, Fabio; Rosoldi, Marco; Pappalardo, Gelsomina; Welton, Ellsworth J.

    2016-04-01

    The aerosol and cloud impact on climate change is evaluated in terms of enhancement or reduction of the radiative energy, or heat, available in the atmosphere and at the Earth's surface, from the surface (SFC) to the Top Of the Atmosphere (TOA) covering a spectral range from the UV (extraterrestrial shortwave solar radiation) to the far-IR (outgoing terrestrial longwave radiation). Systematic Lidar network measurements from permanent observational sites across the globe are available from the beginning of this current millennium. From the retrieved lidar atmospheric extinction profiles, inputted in the Fu-Liou-Gu (FLG) Radiative Transfer code, it is possible to evaluate the net radiative effect and heating rate of the different aerosol species and clouds. Nevertheless, the lidar instruments may use different techniques (elastic lidar, Raman lidar, multi-wavelength lidar, etc) that translate into uncertainty of the lidar extinction retrieval. The goal of this study is to assess, applying a MonteCarlo technique and the FLG Radiative Transfer model, the sensitivity in calculating the net radiative effect and heating rate of aerosols and clouds for the different lidar techniques, using both synthetic and real lidar data. This sensitivity study is the first step to implement an automatic algorithm to retrieve the net radiative forcing effect of aerosols and clouds from the long records of aerosol measurements available in the frame of EARLINET and MPLNET lidar networks.

  2. MAX-DOAS observations of aerosols, formaldehyde and nitrogen dioxide in the Beijing area: comparison of two profile retrieval approaches

    NASA Astrophysics Data System (ADS)

    Vlemmix, T.; Hendrick, F.; Pinardi, G.; De Smedt, I.; Fayt, C.; Hermans, C.; Piters, A.; Levelt, P.; Van Roozendael, M.

    2014-09-01

    A four year data set of MAX-DOAS observations in the Beijing area (2008-2012) is analysed with a focus on NO2, HCHO, and aerosols. Two very different retrieval methods are applied. Method A describes the tropospheric profile with 13 layers and makes use of the optimal estimation method. Method B uses 2-4 parameters to describe the tropospheric profile and an inversion based on a least-squares fit. For each constituent (NO2, HCHO and aerosols) the retrieval outcomes are compared in terms of tropospheric columns, surface concentrations, and "characteristic profile heights" (i.e. the height below which 75% of the vertically integrated tropospheric column resides). We find best agreement between the two methods for tropospheric NO2 columns, with a standard deviation of relative differences below 10%, a correlation of 0.99 and a linear regression with a slope of 1.03. For tropospheric HCHO columns we find a similar slope, but also a systematic bias of almost 10% which is likely related to differences in profile height. Aerosol optical depths (AODs) retrieved with method B are 20% high compared to method A. They are more in agreement with AERONET measurements, which are on average only 5% lower, however with considerable relative differences (standard deviation ~25%). With respect to near surface volume mixing ratios and aerosol extinction we find considerably larger relative differences: 10 ± 30%, -23 ± 28% and -8 ± 33% for aerosols, HCHO and NO2 respectively. The frequency distributions of these near-surface concentrations show however a quite good agreement, and this indicates that near-surface concentrations derived from MAX-DOAS are certainly useful in a climatological sense. A major difference between the two methods is the dynamic range of retrieved characteristic profile heights which is larger for method B than for method A. This effect is most pronounced for HCHO, where retrieved profile shapes with method A are very close to the a priori, and moderate for

  3. MAX-DOAS observations of aerosols, formaldehyde and nitrogen dioxide in the Beijing area: comparison of two profile retrieval approaches

    NASA Astrophysics Data System (ADS)

    Vlemmix, T.; Hendrick, F.; Pinardi, G.; De Smedt, I.; Fayt, C.; Hermans, C.; Piters, A.; Wang, P.; Levelt, P.; Van Roozendael, M.

    2015-02-01

    A 4-year data set of MAX-DOAS observations in the Beijing area (2008-2012) is analysed with a focus on NO2, HCHO and aerosols. Two very different retrieval methods are applied. Method A describes the tropospheric profile with 13 layers and makes use of the optimal estimation method. Method B uses 2-4 parameters to describe the tropospheric profile and an inversion based on a least-squares fit. For each constituent (NO2, HCHO and aerosols) the retrieval outcomes are compared in terms of tropospheric column densities, surface concentrations and "characteristic profile heights" (i.e. the height below which 75% of the vertically integrated tropospheric column density resides). We find best agreement between the two methods for tropospheric NO2 column densities, with a standard deviation of relative differences below 10%, a correlation of 0.99 and a linear regression with a slope of 1.03. For tropospheric HCHO column densities we find a similar slope, but also a systematic bias of almost 10% which is likely related to differences in profile height. Aerosol optical depths (AODs) retrieved with method B are 20% high compared to method A. They are more in agreement with AERONET measurements, which are on average only 5% lower, however with considerable relative differences (standard deviation ~ 25%). With respect to near-surface volume mixing ratios and aerosol extinction we find considerably larger relative differences: 10 ± 30, -23 ± 28 and -8 ± 33% for aerosols, HCHO and NO2 respectively. The frequency distributions of these near-surface concentrations show however a quite good agreement, and this indicates that near-surface concentrations derived from MAX-DOAS are certainly useful in a climatological sense. A major difference between the two methods is the dynamic range of retrieved characteristic profile heights which is larger for method B than for method A. This effect is most pronounced for HCHO, where retrieved profile shapes with method A are very close to the

  4. 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.

  5. The effects of increasing atmospheric ozone on biogenic monoterpene profiles and the formation of secondary aerosols

    NASA Astrophysics Data System (ADS)

    Pinto, Delia M.; Tiiva, Päivi; Miettinen, Pasi; Joutsensaari, Jorma; Kokkola, Harri; Nerg, Anne-Marja; Laaksonen, Ari; Holopainen, Jarmo K.

    Monoterpenes are biogenic volatile organic compounds (BVOCs) which play an important role in plant adaptation to stresses, atmospheric chemistry, plant-plant and plant-insect interactions. In this study, we determined whether ozonolysis can influence the monoterpenes in the headspace of cabbage. The monoterpenes were mixed with an air-flow enriched with 100, 200 or 400 ppbv of ozone (O 3) in a Teflon chamber. The changes in the monoterpene and O 3 concentrations, and the formation of secondary organic aerosols (SOA) were determined during ozonolysis. Furthermore, the monoterpene reactions with O 3 and OH were modelled using reaction kinetics equations. The results showed that all of the monoterpenes were unequally affected: α-thujene, sabinene and D-limonene were affected to the greatest extend, whereas the 1,8-cineole concentration did not change. In addition, plant monoterpene emissions reduced the O 3 concentration by 12-24%. The SOA formation was dependent on O 3 concentration. At 100 ppbv of O 3, virtually no new particles were formed but clear SOA formation was observed at the higher ozone concentrations. The modelled results showed rather good agreements for α-pinene and 1,8-cineole, whereas the measured concentrations were clearly lower compared to modelled values for sabinene and limonene. In summary, O 3-quenching by monoterpenes occurs beyond the boundary layer of leaves and results in a decreased O 3 concentration, altered monoterpene profiles and SOA formation.

  6. Cloud and Aerosol Properties, Precipitable Water, and Profiles of Temperature and Water Vapor from MODIS

    NASA Technical Reports Server (NTRS)

    King, Michael D.; Menzel, W. Paul; Kaufman, Yoram J.; Tanre, Didier; Gao, Bo-Cai; Platnick, Steven; Ackerman, Steven A.; Remer, Lorraine A.; Pincus, Robert; Hubanks, Paul A.

    2003-01-01

    The Moderate Resolution Imaging Spectroradiometer (MODIS) is an earth-viewing sensor that flies on the Earth Observing System (EOS) Terra and Aqua satellites, launched in 1999 and 2002, respectively. MODIS scans a swath width of 2330 km that is sufficiently wide to provide nearly complete global coverage every two days from a polar-orbiting, sun-synchronous, platform at an altitude of 705 km. MODIS provides images in 36 spectral bands between 0.415 and 14.235 pm with spatial resolutions of 250 m (2 bands), 500 m (5 bands) and 1000 m (29 bands). These bands have been carefully selected to en- able advanced studies of land, ocean, and atmospheric properties. Twenty-six bands are used to derive atmospheric properties such as cloud mask, atmospheric profiles, aerosol properties, total precipitable water, and cloud properties. In this paper we describe each of these atmospheric data products, including characteristics of each of these products such as file size, spatial resolution used in producing the product, and data availability.

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

    NASA Technical Reports Server (NTRS)

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

    2008-01-01

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

  8. Local - Air Project: Tropospheric Aerosol Monitoring by CALIPSO Lidar Satellite and Ground-Based Observations

    NASA Astrophysics Data System (ADS)

    Sarli, V.; Trippetta, S.; Bitonto, P.; Papagiannopoulos, N.; Caggiano, R.; Donvito, A.; Mona, L.

    2016-06-01

    A new method for the detection of the Planetary Boundary Layer (PBL) height from CALIPSO space-borne lidar data was developed and the possibility to infer the sub-micrometric aerosol particle (i.e., PM1) concentrations at ground level from CALIPSO observations was also explored. The comparison with ground-based lidar measurements from an EARLINET (European Aerosol Research LIdar Network) station showed the reliability of the developed method for the PBL. Moreover, empirical relationships between integrated backscatter values from CALIPSO and PM1 concentrations were found thanks to the combined use of the retrieved PBL heights, CALIPSO aerosol profiles and typing and PM1 insitu measurements.

  9. SAM II aerosol profile measurements, Poker Flat, Alaska; July 16-19, 1979

    NASA Technical Reports Server (NTRS)

    Mccormick, M. P.; Chu, W. P.; Mcmaster, L. R.; Grams, G. W.; Herman, B. M.; Pepin, T. J.; Russell, P. B.; Swissler, T. J.

    1981-01-01

    SAM II satellite measurements during the July 1979 Poker Flat mission, yielded an aerosol extinction coefficient of 0.0004/km at 1.0 micron wavelength, in the region of the stratospheric aerosol mixing ratio peak (12-16 km). The stratospheric aerosol optical depth for these data, calculated from the tropopause through 30 km, is approximately 0.001. These results are consistent with the average 1979 summertime values found throughout the Arctic.

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

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

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

  11. LASE measurements of water vapor and aerosol profiles during the Plains Elevated Convection at Night (PECAN) field experiment

    NASA Astrophysics Data System (ADS)

    Nehrir, A. R.; Ferrare, R. A.; Kooi, S. A.; Butler, C. F.; Notari, A.; Hair, J. W.; Collins, J. E., Jr.; Ismail, S.

    2015-12-01

    The Lidar Atmospheric Sensing Experiment (LASE) system was deployed on the NASA DC-8 aircraft during the Plains Elevated Convection At Night (PECAN) field experiment, which was conducted during June-July 2015 over the central and southern plains. LASE is an active remote sensor that employs the differential absorption lidar (DIAL) technique to measure range resolved profiles of water vapor and aerosols above and below the aircraft. The DC-8 conducted nine local science flights from June 30- July 14 where LASE sampled water vapor and aerosol fields in support of the PECAN primary science objectives relating to better understanding nocturnal Mesoscale Convective Systems (MCSs), Convective Initiation (CI), the Low Level Jet (LLJ), bores, and to compare different airborne and ground based measurements. LASE observed large spatial and temporal variability in water vapor and aerosol distributions in advance of nocturnal MCSs, across bores resulting from MCS outflow boundaries, and across the LLJ associated with the development of MCSs and CI. An overview of the LASE data collected during the PECAN field experiment will be presented where emphasis will be placed on variability of water vapor profiles in the vicinity of severe storms and intense convection in the central and southern plains. Preliminary comparisons show good agreement between coincident LASE and radiosonde water vapor profiles. In addition, an advanced water vapor DIAL system being developed at NASA Langley will be discussed.

  12. The Potential of The Synergy of Sunphotometer and Lidar Data to Validate Vertical Profiles of The Aerosol Mass Concentration Estimated by An Air Quality Model

    NASA Astrophysics Data System (ADS)

    Siomos, N.; Filioglou, M.; Poupkou, A.; Liora, N.; Dimopoulos, S.; Melas, D.; Chaikovsky, A.; Balis, D. S.

    2016-06-01

    Vertical profiles of the aerosol mass concentration derived by the Lidar/Radiometer Inversion Code (LIRIC), that uses combined sunphotometer and lidar data, were used in order to validate the aerosol mass concentration profiles estimated by the air quality model CAMx. Lidar and CIMEL measurements performed at the Laboratory of Atmospheric Physics of the Aristotle University of Thessaloniki, Greece (40.5N, 22.9E) from the period 2013-2014 were used in this study.

  13. Validation of aerosol extinction and water vapor profiles from routine Atmospheric Radiation Measurement Climate Research Facility measurements

    SciTech Connect

    Schmid, Beat; Flynn, Connor J.; Newsom, Rob K.; Turner, David D.; Ferrare, Richard; Clayton, Marian F.; Ogren, John A.; Russell, P. B.; Gore, W.; Dominguez, Roseanne

    2009-11-26

    The accuracy with which vertical profiles of aerosol extinction σep(λ) can be retrieved from ARM Climate Research Facility (ACRF) routine measurements was assessed using data from two airborne field campaigns, the ARM Aerosol Intensive Operation Period (AIOP, May 2003), and the Aerosol Lidar Validation Experiment (ALIVE, September 2005). This assessment pertains to the aerosol at its ambient concentration and thermodynamic state (i.e. σep(λ) either free of or corrected for sampling artifacts) and includes the following ACRF routine methods: Raman Lidar, Micro Pulse Lidar (MPL) and in-situ aerosol profiles (IAP) with a small aircraft. Profiles of aerosol optical depth τp(λ), from which the profiles of σep(λ)are derived through vertical differentiation, were measured by the NASA Ames Airborne Tracking 14-channel Sunphotometer (AATS-14); these data were used as truth in this evaluation. The ACRF IAP σep(550 nm) were lower by 16% (during AIOP) and higher by 10% (during ALIVE) when compared to AATS-14. The ACRF MPL σep(523 nm) were higher by 24% (AIOP) and 19%-21% (ALIVE) compared to AATS-14 but the correlation improved significantly during ALIVE. In the AIOP a second MPL operated by NASA showed a smaller positive bias (13%) with respect to AATS-14. The ACRF Raman Lidar σep(355 nm) were higher by 54% (AIOP) and higher by 6% (ALIVE) compared to AATS-14. The large bias in AIOP stemmed from a gradual loss of the sensitivity of the Raman Lidar starting about the end of 2001 going unnoticed until after AIOP. A major refurbishment and upgrade of the instrument and improvements to a data-processing algorithm led to the significant improvement and very small bias in ALIVE. Finally we find that during ALIVE the Raman Lidar water vapor densities ρw are higher by 8% when compared to AATS-14, whereas comparisons between AATS-14 and in-situ measured ρw aboard two different aircraft showed small negative biases (0 to

  14. 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

  15. Biogenic VOC oxidation and organic aerosol formation in an urban nocturnal boundary layer: aircraft vertical profiles in Houston, TX

    NASA Astrophysics Data System (ADS)

    Brown, S. S.; Dubé, W. P.; Bahreini, R.; Middlebrook, A. M.; Brock, C. A.; Warneke, C.; de Gouw, J. A.; Washenfelder, R. A.; Atlas, E.; Peischl, J.; Ryerson, T. B.; Holloway, J. S.; Schwarz, J. P.; Spackman, R.; Trainer, M.; Parrish, D. D.; Fehshenfeld, F. C.; Ravishankara, A. R.

    2013-05-01

    Organic compounds are a large component of aerosol mass, but organic aerosol (OA) sources remain poorly characterized. Recent model studies have suggested nighttime oxidation of biogenic hydrocarbons as a potentially large OA source, but analysis of field measurements to test these predictions is sparse. We present nighttime vertical profiles of nitrogen oxides, ozone, VOCs and aerosol composition measured during low approaches of the NOAA P-3 aircraft to airfields in Houston, TX. This region has large emissions of both biogenic hydrocarbons and nitrogen oxides. The latter serves as a source of the nitrate radical, NO3, a key nighttime oxidant. Biogenic VOCs (BVOC) and urban pollutants were concentrated within the nocturnal boundary layer (NBL), which varied in depth from 100-400 m. Despite concentrated NOx at low altitude, ozone was never titrated to zero, resulting in rapid NO3 radical production rates of 0.2-2.7ppbv h-1 within the NBL. Monoterpenes and isoprene were frequently present within the NBL and underwent rapid oxidation (up to 1ppbv h-1), mainly by NO3 and to a lesser extent O3. Concurrent enhancement in organic and nitrate aerosol on several profiles was consistent with primary emissions and with secondary production from nighttime BVOC oxidation, with the latter equivalent to or slightly larger than the former. Ratios of organic aerosol to CO within the NBL ranged from 14 to 38 μg m-3 OA/ppmv CO. A box model simulation incorporating monoterpene emissions, oxidant formation rates and monoterpene SOA yields suggested overnight OA production of 0.5 to 9 μg m-3.

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

    NASA Astrophysics Data System (ADS)

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

    2008-11-01

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

  17. CALIPSO-inferred aerosol direct radiative effects: Bias estimates using ground-based Raman lidars

    NASA Astrophysics Data System (ADS)

    Thorsen, Tyler J.; Fu, Qiang

    2015-12-01

    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, uncertainties in CALIPSO-inferred aerosol DRE are estimated using multiple years of observations from the Atmospheric Radiation Measurement (ARM) program's Raman lidars at midlatitude and tropical sites. We find that CALIPSO is unable to detect all radiatively significant aerosol, resulting in an underestimate in the magnitude of the aerosol DRE by 30-50% at the two ARM sites. The undetected aerosol is likely the consequence of random noise in CALIPSO measurements and therefore will affect global observations as well. This suggests that the global aerosol DRE inferred from CALIPSO observations are likely too weak. Also examined is the impact of the ratio of extinction-to-backscatter (i.e., the lidar ratio) whose value CALIPSO retrievals must assume to obtain the aerosol extinction profile. It is shown that if CALIPSO can reproduce the climatological value of the lidar ratio at a given location, then the aerosol DRE there can be accurately calculated (within about 3%).

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

    NASA Astrophysics Data System (ADS)

    Liu, Jun; Hua, Dengxin

    2008-10-01

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

  19. Aerosol Optical Properties at NEAQS 2002 From Lidar, Sunphotometer, and Integrating Nephelometer

    NASA Astrophysics Data System (ADS)

    Eberhard, W. L.; Senff, C. J.; Quinn, P. K.; Alvarez, R. J.; McCarty, B. J.

    2003-12-01

    Optical measurements of aerosols were performed from the NOAA Research Vessel Ron Brown near the east coast of the United States for 3 weeks starting mid-July 2002. The instruments included a lidar (355 nm wavelength), a handheld sunphotometer (380, 440, 500, 675, and 870 nm), and an integrating nephelometer (450, 550, and 700 nm). Lidar extinction profiles are derived with constraint from the sunphotometer aerosol optical depth data when available. Typical extinction-to-backscatter values from these measurements for the same airmass types are used to retrieve extinction profiles at night and in cloudy periods. Temperature profile and wind shear data from radiosondes and vertical smoothness of the lidar backscatter profile are used to determine the vertical extent of the layer in which the aerosol particles can be considered well mixed. The fraction of the total column aerosol that is characterized by the near-surface in situ measurements is estimated from the lidar profile and depth of the mixed layer. Extinction values from the lowest gates of the lidar are compared with the nephelometer's aerosol scatter data when the atmosphere is apparently well mixed between the two heights. The optical characteristics for various sources (urban, rural, and maritime) are contrasted.

  20. Vertical profiles of atmospheric fluorescent aerosols observed by a mutil-channel lidar spectrometer system

    NASA Astrophysics Data System (ADS)

    Huang, Z.; Huang, J.; Zhou, T.; Sugimoto, N.; Bi, J.

    2015-12-01

    Zhongwei Huang1*, Jianping Huang1, Tian Zhou1, Nobuo Sugimoto2, Jianrong Bi1 and Jinsen Shi11Key Laboratory for Semi-Arid Climate Change of the Ministry of Education, College of Atmospheric Sciences, Lanzhou University, Lanzhou, China. 2Atmospheric Environment Division, National Institutes for Environmental Studies, Tsukuba, Japan Email: huangzhongwei@lzu.edu.cn Abstract Atmospheric aerosols have a significant impact on regional and globe climate. The challenge in quantifying aerosol direct radiative forcing and aerosol-cloud interactions arises from large spatial and temporal heterogeneity of aerosol concentrations, compositions, sizes, shape and optical properties (IPCC, 2007). Lidar offers some remarkable advantages for determining the vertical structure of atmospheric aerosols and their related optical properties. To investigate the characterization of atmospheric aerosols (especially bioaerosols) with high spatial and temporal resolution, we developed a Raman/fluorescence/polarization lidar system employed a multi-channel spectrometer, with capabilities of providing measurements of Raman scattering and laser-induced fluorescence excitation at 355 nm from atmospheric aerosols. Meanwhile, the lidar system operated polarization measurements both at 355nm and 532nm wavelengths, aiming to obtain more information of aerosols. It employs a high power pulsed laser and a received telescope with 350mm diameter. The receiver could simultaneously detect a wide fluorescent spectrum about 178 nm with spectral resolution 5.7 nm, mainly including an F/3.7 Crossed Czerny-Turner spectrograph, a grating (1200 gr/mm) and a PMT array with 32 photocathode elements. Vertical structure of fluorescent aerosols in the atmosphere was observed by the developed lidar system at four sites across northwest China, during 2014 spring field observation that conducted by Lanzhou University. It has been proved that the developed lidar could detect the fluorescent aerosols with high temporal and

  1. Profiling of aerosol microphysical properties at several EARLINET/AERONET sites during July 2012 ChArMEx/EMEP campaign

    NASA Astrophysics Data System (ADS)

    Granados-Muñoz, M. J.; Navas-Guzmán, F.; Guerrero-Rascado, J. L.; Bravo-Aranda, J. A.; Binietoglou, I.; Pereira, S. N.; Basart, S.; Baldasano, J. M.; Belegante, L.; Chaikovsky, A.; Comerón, A.; D'Amico, G.; Dubovik, O.; Ilic, L.; Kokkalis, P.; Muñoz-Porcar, C.; Nickovic, S.; Nicolae, D.; Olmo, F. J.; Papayannis, A.; Pappalardo, G.; Rodríguez, A.; Schepanski, K.; Sicard, M.; Vukovic, A.; Wandinger, U.; Dulac, F.; Alados-Arboledas, L.

    2015-11-01

    The analysis of aerosol microphysical properties profiles at different European stations is made in the framework of the ChArMEx/EMEP 2012 field campaign (9-11 July 2012). During and in support to this campaign, five lidar ground-based stations (Athens, Barcelona, Bucharest, Évora and Granada) performed 72 h of continuous lidar and collocated and coincident sun-photometer measurements. Therefore it was possible to retrieve volume concentration profiles with the Lidar Radiometer Inversion Code (LIRIC). Results indicated the presence of a mineral dust plume affecting the Western Mediterranean region (mainly Granada station) whereas a different aerosol plume was observed over the Balkans area. LIRIC profiles showed a predominance of coarse spheroid particles above Granada, as expected for mineral dust, and an aerosol plume composed mainly of fine and coarse spherical particles above Athens and Bucharest. Due to the exceptional characteristics of the ChArMEx database, the analysis of the microphysical properties profiles temporal evolution was also possible. An in depth analysis was performed mainly at Granada station because of the availability of continuous lidar measurements and frequent AERONET inversion retrievals. The analysis at Granada was of special interest since the station was affected by mineral dust during the complete analyzed period. LIRIC was found to be a very useful tool for performing continuous monitoring of mineral dust, allowing for the analysis of the dynamics of the dust event in the vertical and temporal coordinates. Results obtained here illustrate the importance of having collocated and simultaneous advanced lidar and sun-photometer measurements in order to characterize the aerosol microphysical properties both in the vertical and temporal coordinates at a regional scale. In addition, this study revealed that the use of the depolarization information as input in LIRIC in the stations of Bucharest, Évora and Granada was crucial for the

  2. Tropical and Midlatitude Cirrus Cloud Extinction and Backscatter From Multiyear Raman Lidar Measurements.

    NASA Astrophysics Data System (ADS)

    Thorsen, T. J.; Fu, Q.

    2014-12-01

    Lidars have the capability to provide unparalleled range-resolved observations of particulate extinction. However, lidars fundamentally measure backscattered energy, not extinction, and for widely prevalent single-channel elastic backscatter lidars extinction must be obtained by assuming a backscatter-extinction relationship. Our knowledge of this relationship, known as the lidar ratio, mainly consists values determined via the transmission-loss method: which can only provide layer-averaged values and is only applicable to a subset of all cloud layers. Directly-retrieved, vertically resolved extinction coefficients and lidar ratios are obtainable through the use of more advance high spectral resolution lidars (HSRL) or Raman lidars (RL). However, the complexity of operating a HSRL or RL has limited their use for cloud observations to very limited time periods: typical only a few months or less. In this work, we present a newly developed retrieval for the Atmospheric Radiation Measurement (ARM) program's Raman lidars for Feature detection and EXtinction retrieval (FEX). FEX improves upon existing ARM products by using multiple, complimentary quantities to identify both clouds and aerosols and retrieve their extinction and backscatter profiles. Multiple years of data are examined at both the Lamont, Oklahoma and Darwin, Australia ARM sites; providing the most comprehensive climatology to date of cirrus extinction and lidar ratios. Variations in these optical properties with classification of the synoptic state and their relationship with microphysical parameters (temperature, relative humidity and depolarization) are examined.

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

    PubMed

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

    2014-08-25

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

  4. Comparison of stratospheric aerosol and gas experiment I (SAGE I) and Umkehr ozone profiles including a search for Umkehr aerosol effects

    SciTech Connect

    Newchurch, M.J.

    1986-01-01

    After briefly reviewing ozone depletion predictions from atmospheric models and results from trend analysis of Umkehr data, this paper outlines the Umkehr method for deducing the vertical profile of ozone and reviews the theoretical and empirical studies of the aerosol effect on Umkehr measurements. A brief description of the Stratospheric Aerosol and Gas Experiment I (SAGE I) is followed by a method for approximating the best representation of the conditions over the Umkehr ground site as seen by the SAGE I satellite. Using a spatially weighted average of SAGE I events derived from an autocorrelation analysis, the authors find 337 co-located SAGE I and Umkehr events. The approximate total column ozone measured by SAGE I is 5% higher than that measured by Umkehr on average. Most of this difference resides in Umkehr layer two, three, and four, while layers seven, eight, and nine contain small differences in average ozone content. Intercomparison with four other ozone studies indicates agreement between SAGE I and SBUV in most layers and at most Umkehr stations north of 30/sup 0/. However, significant differences in Umkehr layer eight between SAGE I and SBUV remain. Ozone differences between SAGE I and Umkehr are strong functions of both total column ozone and season in the lower layers but not in the upper layers.

  5. New capabilities for space-based cloud and aerosols measurements: The Cloud-Aerosol Transport System (CATS)

    NASA Astrophysics Data System (ADS)

    Yorks, J. E.; McGill, M. J.; Hlavka, D. L.; Palm, S. P.; Hart, W. D.; Nowottnick, E. P.; Vaughan, M.; Rodier, S. D.; Colarco, P. R.; da Silva, A.; Buchard-Marchant, V.

    2013-12-01

    Current uncertainties in cloud and aerosol properties limit our ability to accurately model the Earth's climate system and predict climate change. These limitations are due primarily to difficulties in adequately measuring aerosols and clouds on a global scale. NASA's A-Train satellites provide an unprecedented opportunity to address these uncertainties. In particular, the Cloud-Aerosol Lidar Infrared Pathfinder Spaceborne Observations (CALIPSO) satellite provides vertical profiles of cloud and aerosol properties. The CALIOP lidar onboard CALIPSO has reached its seventh year of operation, well past its expected lifetime. The ATLID lidar on EarthCARE is not expected to launch until 2016 or later. If the CALIOP lidar fails before a new mission is operational, there will be a gap in global lidar measurements. The Cloud-Aerosol Transport System (CATS), built at NASA Goddard Space Flight Center as a payload for the International Space Station (ISS), is set to launch in the summer of 2014. CATS is an elastic backscatter lidar with three wavelengths (1064, 532, 355 nm) and HSRL capability at 532 nm. Depolarization measurements will be made at all three wavelengths. The ISS orbit is a 51 degree inclination orbit at an altitude of about 405 km. This orbit provides more comprehensive coverage of the tropics and mid-latitudes than sun-synchronous orbiting sensors, with nearly a three day repeat cycle. Thus, science applications of CATS include cloud and aerosol climate studies, air quality monitoring, and smoke/volcanic plume tracking. The primary science objectives of CATS include: continuing the CALIPSO aerosol and cloud vertical profile data record, providing near real time data to support operational applications such as air quality modeling, and advancing technology in support of future mission development using the HSRL channel. Furthermore, the vertical profiles of cloud and aerosol properties provided by CATS will complement current and future passive satellite

  6. 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).

  7. Raman Lidar Measurements of Aerosol Optical Properties Performed at CNR- IMAA

    NASA Astrophysics Data System (ADS)

    Mona, L.; Amodeo, A.; Cornacchia, C.; D'Amico, G.; Madonna, F.; Pandolfi, M.; Pappalardo, G.

    2005-12-01

    The lidar system for tropospheric aerosol study, located at CNR-IMAA in Tito Scalo, Potenza (40 °36'N, 15°44' E, 760 m above sea level), is a Raman/elastic lidar system operational since May 2000 in the framework of EARLINET (European Aerosol Research LIdar NETwork), the first lidar network for tropospheric aerosol study on continental scale. It provides independent measurements of aerosol extinction and backscatter coefficient profiles at 355 nm and aerosol backscatter profiles at 532 nm. Both the IMAA aerosol lidar system and the used algorithms for the retrieval of aerosol optical parameters have been successfully tested with different intercomparison exercises in the frame of the EARLINET quality assurance program. In the frame of EARLINET, regular measurements are performed three times per week, allowing to study the aerosol content typically present in the planetary boundary layer over Potenza. Particular attention is devoted to Saharan dust intrusions in Europe, and Saharan dust forecasts are distributed to all EARLINET stations. The large dataset of Saharan dust optical properties profiles collected at IMAA allowed to study the contribution of dust particles to the aerosol load typically present in our area as well as to investigate transformations of aerosol optical properties during the transport. Several intensive measurement campaigns have been performed at IMAA with this system to study optical properties of different types of aerosol, and how the transport and modification mechanisms and the water content affect these optical properties. In particular, direct transport of volcanic aerosol emitted in 2002 during the Etna eruptions was observed, and in summer 2004, aerosol layers related to forest fires smoke or pollution plume transported from Alaska, Canada and North America were observed at IMAA during the International Consortium for Atmospheric Research on Transport and Transformation (ICARTT) field campaign. Moreover, this system has been used

  8. CALIPSO-inferred aerosol direct radiative effects: Bias estimates using ground-based Raman lidars

    NASA Astrophysics Data System (ADS)

    Thorsen, T. J.; Fu, Q.

    2015-12-01

    Observational constraints on the change in 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 detection all radiatively-significant aerosol, resulting in an underestimate in the magnitude of the aerosol DRE. Therefore, global estimates of the aerosol DRE inferred from CALIPSO are likely too weak.

  9. On observing acoustic backscattering from salinity turbulence.

    PubMed

    Goodman, Louis; Sastre-Cordova, Marcos M

    2011-08-01

    It has been hypothesized that at sufficiently high levels of oceanic salinity turbulence it should be possible to observe acoustic backscattering. However, there have been limited in situ measurements to confirm this hypothesis. Using an autonomous underwater vehicle equipped with upward and downward looking 1.2 MHz acoustic Doppler current profilers and with turbulence and fine scale sensors, measurements were performed in a region of intense turbulence and a strong salinity gradient. The approach taken was to correlate variations in the backscattered acoustic intensity, I, with a theoretical acoustic backscattering cross section per volume for salinity turbulence, σ(s), to obtain an estimated scattering cross section per volume, σ(e). Results indicated that of order 50% of the observed region was characterized by salinity turbulence induced backscattering. PMID:21877785

  10. 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

  11. Dynamic coherent backscattering mirror

    NASA Astrophysics Data System (ADS)

    Zeylikovich, I.; Xu, M.

    2016-02-01

    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.

  12. Aerosol characteristics in the UTLS region: A satellite-based study over north India

    NASA Astrophysics Data System (ADS)

    Srivastava, A. K.; Misra, A.; Kanawade, Vijay P.; Devara, P. C. S.

    2016-01-01

    Vertical profiles of aerosol backscatter coefficient and depolarization ratio, obtained from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite, were studied in the upper troposphere and lower stratosphere (UTLS) region over North India (21-30° N and 72-90° E), covering the highly polluted Indo-Gangetic Plain (IGP) for one-year period from December 2011 to November 2012. An enhanced aerosol layer was observed between 15 and 18 km altitude, in the vicinity of tropopause, with a broad layer depth of about 2 km. The aerosol layer showed strong seasonal, monthly as well as day and night time variability, with a peak value of backscatter coefficient during monsoon season (˜5.54 × 10-3 sr-1 in September). The corresponding depolarization ratio indicates anisotropic (non-spherical) nature of particles. The aerosol layer was found to be highly linked with the variability in tropopause height, showing a positive correlation between tropopause height and the height of maximum backscatter coefficient (correlation coefficient of 0.8). However, it was found to be negatively correlated with the integrated backscatter coefficient (IBC), with a correlation coefficient of 0.3. We further analyzed outgoing long-wave radiation (OLR) data during the study period to investigate the link between the observed enhanced aerosol layer in the UTLS region and prevailing deep convective activities over the study region. Low values of OLR during monsoon (about 214 W m-2) indicate the occurrence of deep convection over this region, which may cause a large-scale circulation-driven vertical transport of boundary-layer pollution into the atmosphere of UTLS region. Results may have potential implications for better understanding and assessing the chemical and radiative impacts of these aerosols in the tropical UTLS region.

  13. Measuring the stratospheric aerosol size distribution profile following the next big volcanic eruption. What is required?

    NASA Astrophysics Data System (ADS)

    Deshler, T.

    2015-12-01

    Two of the key missing features of fresh and evolving volcanic plumes are the particle size distribution and its partitioning into non-volatile ash and volatile sulfate particles. Such information would allow more refined estimates of the evolution and dispersal of the aerosol, of the impacts of the aerosol on radiation and on stratospheric chemistry, and of the overall amount of sulfur injected into the stratosphere. To provide this information aerosol measurements must be sensitive to particles in the 0.1 - 10 μm radius range, with concentration detection thresholds > 0.001 cm-3, and to the total aerosol population. An added bonus would be a size resolved measurement of the non-volatile fraction of the aerosol. The measurements must span the lower and mid stratosphere up to about 30 km. There are no remote measurements which can provide this information. In situ measurements using aerosol and condensation nuclei counters are required. Aircraft platforms are available for measurements up to 20 km, but beyond that requires balloon platforms. Measurements above 20 km would be required for a large volcanic eruption. There are balloon-borne instruments capable of fulfilling all of the measurement requirements; however such instruments are reasonably large and not expendable. The difficulty is deploying the instruments, obtaining the flight permissions from air traffic control, and recovering the instruments after flight. Such difficulties are compounded in the tropics. This talk will detail some previous experience in this area and suggest ways forward to be ready for the next big eruption.

  14. Scanning tropospheric ozone and aerosol lidar with double-gated photomultipliers.

    PubMed

    Machol, Janet L; Marchbanks, Richard D; Senff, Christoph J; McCarty, Brandi J; Eberhard, Wynn L; Brewer, William A; Richter, Ronald A; Alvarez, Raul J; Law, Daniel C; Weickmann, Ann M; Sandberg, Scott P

    2009-01-20

    The Ozone Profiling Atmospheric Lidar is a scanning four-wavelength ultraviolet differential absorption lidar that measures tropospheric ozone and aerosols. Derived profiles from the lidar data include ozone concentration, aerosol extinction, and calibrated aerosol backscatter. Aerosol calibrations assume a clear air region aloft. Other products include cloud base heights, aerosol layer heights, and scans of particulate plumes from aircraft. The aerosol data range from 280 m to 12 km with 5 m range resolution, while the ozone data ranges from 280 m to about 1.2 km with 100 m resolution. In horizontally homogeneous atmospheres, data from multiple-elevation angles is combined to reduce the minimum altitude of the aerosol and ozone profiles to about 20 m. The lidar design, the characterization of the photomultiplier tubes, ozone and aerosol analysis techniques, and sample data are described. Also discussed is a double-gating technique to shorten the gated turn-on time of the photomultiplier tubes, and thereby reduce the detection of background light and the outgoing laser pulse. PMID:19151820

  15. Saharan Desert Dust Sources: New Insights Based on Aerosol Vertical Profiles Retrieved from Thermal Infrared Measurements by IASI

    NASA Astrophysics Data System (ADS)

    Vandenbussche, S.; Kumps, N.; Vandaele, A. C.; De Maziere, M.

    2015-06-01

    Desert dust is a major actor in the climate and one of the least characterized with respect to its radiative forcing, both direct and indirect. Studies of dust atmospheric load and sources are therefore of great scientific interest. In the last years, we have developed and improved a retrieval strategy to obtain desert dust aerosols vertical profiles, from thermal infrared measurements by IASI. This strategy has been used to process significant amount of IASI data above North Africa. This dataset allows a new insight in the study of Saharan desert dust sources: it provides twice a day, at interesting times considering the dust emission diurnal cycle, vertical profiles of desert dust (not only optical depth), making possible to distinguish local emissions from transported dust.

  16. 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

  17. 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.

  18. Vertical variations of aerosols and the effects responded to the emission control: application of lidar ceilometer in Beijing during APEC, 2014

    NASA Astrophysics Data System (ADS)

    Tang, G.; Zhu, X.; Hu, B.; Xin, J.; Wang, L.; Münkel, C.; Mao, G.; Wang, Y.

    2015-05-01

    During the 2014 Asia-Pacific Economic Cooperation (APEC) summit, a reduction of air pollution sources was coordinated to ensure good air quality in Beijing and the surrounding provinces and cities. By investigating variations in air pollution during this period, the effects of local emissions and regional transport can be better understood and the information can be used to evaluate the effectiveness of emission reduction strategies and provide a theoretical basis to guide future emission reduction strategies. From 15 October to 30 November 2014, the height of the atmospheric mixing layer and the aerosol attenuated backscattering coefficient profile were observed online using a lidar ceilometer. By investigating the correlation between fine particulate matter (PM2.5) data near the surface and attenuated backscattering coefficients measured by the lidar ceilometer as well as the correlation between aerosol optical depth (AOD) and attenuated backscattering coefficients of the 0 to 4500 m column, we found that the attenuated backscattering coefficient measured by the lidar ceilometer is highly correlated with the PM2.5 concentration and AOD (correlation coefficients of 0.89 and 0.86, respectively). This result demonstrates the reliability of the vertical profile of aerosols measured by the lidar ceilometer. By analyzing the atmospheric backscattering profile, we found that during the initial stage of pollution accumulation, which is affected by transport of southerly jet flows at low altitude, the attenuated backscattering coefficient of atmospheric aerosols from 0 to 1500 m was greatly enhanced by approximately 1.4 Mm-1 sr-1 (140%). At the peak pollution stage, the height of the mixing layer gradually decreased, the ratio of CO/SO2 gradually increased and emissions were dominated by local emissions. The attenuated backscattering coefficient of aerosols from 0 to 300 m suddenly increased, and the aerosols near surface had the highest value (approximately 14 Mm-1 sr-1

  19. Study of aerosol hygroscopic events over the Cabauw experimental site for atmospheric research (CESAR) using the multi-wavelength Raman lidar Caeli

    NASA Astrophysics Data System (ADS)

    Fernández, A. J.; Apituley, A.; Veselovskii, I.; Suvorina, A.; Henzing, J.; Pujadas, M.; Artíñano, B.

    2015-11-01

    This article presents a study of aerosol optical and microphysical properties under different relative humidity (RH) but well mixed layer conditions using optical and microphysical aerosol properties from multi-wavelength (MW) Raman lidar and in-situ aerosol observations collected at the Cabauw Experimental Site for Atmospheric Research (CESAR). Two hygroscopic events are described through 3 backscatter (β) and 2 extinction (α) coefficients which in turn provide intensive parameters such as the backscatter-related Ångström exponent (åβ) and the lidar ratio (LR). Along with it, profiles of RH were inferred from Raman lidar observations and therefore, as a result of varying humidity conditions, a shift on the aerosol optical properties can be described. Thus, it is observed that as RH increases, aerosols uptake water vapour, augment their size and consequently the åβ diminishes whereas the LR increases. The enhancement factor based on the backscatter coefficient at 532 nm, which characterizes the aerosol from hygroscopic standpoint, is also estimated. Finally, microphysical properties that are necessary for aerosol radiative forcing estimates - such as volume, effective radii, refractive index and size distribution, all vertically resolved - are retrieved using the inversion with regularization. Using this method, two hygroscopic events are described in detail.

  20. Determination of nocturnal aerosol properties from a combination of lunar photometer and lidar observations

    NASA Astrophysics Data System (ADS)

    Li, Donghui; Li, Zhengqiang; Lv, Yang; Zhang, Ying; Li, Kaitao; Xu, Hua

    2015-10-01

    Aerosol plays a key role in the assessment of global climate change and environmental health, while observation is one of important way to deepen the understanding of aerosol properties. In this study, the newly instrument - lunar photometer is used to measure moonlight and nocturnal column aerosol optical depth (AOD, τ) is retrieved. The AOD algorithm is test and verified with sun photometer both in high and low aerosol loading. Ångström exponent (α) and fine/coarse mode AOD (τf, τc) 1 is derived from spectral AOD. The column aerosol properties (τ, α, τf, τc) inferred from the lunar photometer is analyzed based on two month measurement in Beijing. Micro-pulse lidar has advantages in retrieval of aerosol vertical distribution, especially in night. However, the typical solution of lidar equation needs lidar ratio(ratio of aerosol backscatter and extinction coefficient) assumed in advance(Fernald method), or constrained by AOD2. Yet lidar ratio is varied with aerosol type and not easy to fixed, and AOD is used of daylight measurement, which is not authentic when aerosol loading is different from day and night. In this paper, the nocturnal AOD measurement from lunar photometer combined with mie scattering lidar observations to inverse aerosol extinction coefficient(σ) profile in Beijing is discussed.

  1. 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.

  2. The Cloud-Aerosol Transport System (CATS): Demonstrating New Techniques for Cloud and Aerosol Measurements

    NASA Astrophysics Data System (ADS)

    Yorks, J. E.; McGill, M. J.; Palm, S. P.; Hlavka, D. L.; Nowottnick, E. P.; Selmer, P. A.

    2015-12-01

    The Cloud-Aerosol Transport System (CATS) is an elastic backscatter lidar that provides vertical profiles of cloud and aerosol properties. The CATS payload has been operating since early February 2015 from the International Space Station (ISS). CATS was designed to operate for six months, and up to three years, providing a combination of operational science, in-space technology demonstration, and technology risk reduction for future Earth Science missions. One of the primary project goals of CATS is to demonstrate technology in support of future space-based lidar mission development. The CATS instrument has been demonstrating the high repetition rate laser and photon counting detection approach to lidar observations, in contrast to the low repetition rate, high energy technique employed by CALIPSO. Due to this technique, cloud and aerosol profile data exhibit high spatial and temporal resolution, which was never before possible from a space-based platform. Another important science goal of the CATS-FO project is accurate determination of aerosol type on a global scale. CATS provided the first space-based depolarization measurements at multiple wavelengths (532 and 1064 nm), and first measurements at 1064 nm from space. The ratio of the depolarization measurements at these two wavelengths enables significant improvement in aerosol typing. The CATS retrievals at 1064 nm also provide improvements to detecting aerosols above clouds. The CATS layer identification algorithm is a threshold-based layer detection method that uses the 1064 nm attenuated scattering ratio and also includes a routine to identify clouds embedded within aerosol layers. This technique allows CATS to detect the full extent of the aerosol layers above the cloud, and differentiate these two layers so that the optical properties can be more accurately determined.

  3. Optical properties of Southern Hemisphere aerosols: Report of the joint CSIRO/NASA study

    NASA Technical Reports Server (NTRS)

    Gras, John L.; Platt, C. Martin; Huffaker, R. Milton; Jones, William D.; Kavaya, Michael J.; Gras, John L.

    1988-01-01

    This study was made in support of the LAWS and GLOBE programs, which aim to design a suitable Doppler lidar system for measuring global winds from a satellite. Observations were taken from 5 deg S to 45 deg S along and off the E and SE Australian coast, thus obtaining representative samples over a large latitude range. Observations were made between 0 and 6 km altitude of aerosol physical and chemical properties in situ from the CSIRO F-27 aircraft; of lidar backscatter coefficients at 10.6 micron wavelength from the F-27 aircraft; of lidar backscatter profiles at 0.694 microns at Sale, SE Australia; and of lidar backscatter profiles at 0.532 microns at Cowley Beach, NE Australia. Both calculations and observations in the free troposphere gave a backscatter coefficient of 1-2 x 10 to the -11/m/sr at 10.6 microns, although the accuracies of the instruments were marginal at this level. Equivalent figures were 2-8 x 10 to the -9/m/sr (aerosol) and 9 x 10 to the -9 to 2 x 10 to the -8/m/sr (lidar) at 0.694 microns wavelength at Sale; and 3.7 x 10 to the -9/m/sr (aerosol) and 10 to the -8 to 10 to the -7/m/sr (lidar) at 0.532 microns wavelength at Cowley Beach. The measured backscatter coefficients at 0.694 and 0.532 microns were consistently higher than the values calculated from aerosol size distributions by factors of typically 2 to 10.

  4. Geometrical constraint experimental determination of Raman lidar overlap profile.

    PubMed

    Li, Jian; Li, Chengcai; Zhao, Yiming; Li, Jing; Chu, Yiqi

    2016-06-20

    A simple experimental method to determine the overlap profile of Raman lidar is presented in this paper. Based on Mie and Raman backscattering signals and a geometrically constrained condition, the overlap profile of a Raman lidar system can be determined. Our approach simultaneously retrieves the lidar ratio of aerosols, which is one of the most important sources of uncertainty in the overlap profile determination. The results indicate that the overlap factor is significantly influenced by the lidar ratio in experimental methods. A representative case study indicates that the correction of the overlap profile obtained by this method is practical and feasible. PMID:27409119

  5. 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.

  6. 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

  7. Tropospheric Ozone Lidar Network (TOLNet) - Long-term Tropospheric Ozone and Aerosol Profiling for Satellite Continuity and Process Studies

    NASA Astrophysics Data System (ADS)

    Newchurch, M.; Al-Saadi, J. A.; Alvarez, R. J.; Burris, J.; Cantrell, W.; Chen, G.; De Young, R.; Hardesty, R.; Hoff, R. M.; Kaye, J. A.; kuang, S.; Langford, A. O.; LeBlanc, T.; McDermid, I. S.; McGee, T. J.; Pierce, R.; Senff, C. J.; Sullivan, J. T.; Szykman, J.; Tonnesen, G.; Wang, L.

    2012-12-01

    An interagency research initiative for ground-based ozone and aerosol lidar profiling recently funded by NASA has important applications to air-quality studies in addition to the goal of serving the GEO-CAPE and other air-quality missions. Ozone is a key trace-gas species, a greenhouse gas, and an important pollutant in the troposphere. High spatial and temporal variability of ozone affected by various physical and photochemical processes motivates the high spatio-temporal lidar profiling of tropospheric ozone for improving the simulation and forecasting capability of the photochemical/air-quality models, especially in the boundary layer where the resolution and precision of satellite retrievals are fundamentally limited. It is well known that there are large discrepancies between the surface and upper-air ozone due to titration, surface deposition, diurnal processes, free-tropospheric transport, and other processes. Near-ground ozone profiling has been technically challenging for lidars due to some engineering difficulties, such as near-range saturation, field-of-view overlap, and signal processing issues. This initiative provides an opportunity for us to solve those engineering issues and redesign the lidars aimed at long-term, routine ozone/aerosol observations from the near surface to the top of the troposphere at multiple stations (i.e., NASA/GSFC, NASA/LaRC, NASA/JPL, NOAA/ESRL, UAHuntsville) for addressing the needs of NASA, NOAA, EPA and State/local AQ agencies. We will present the details of the science investigations, current status of the instrumentation development, data access/protocol, and the future goals of this lidar network. Ozone lidar/RAQMS comparison of laminar structures.

  8. Retrieval of high-spectral-resolution lidar for atmospheric aerosol optical properties profiling

    NASA Astrophysics Data System (ADS)

    Liu, Dong; Luo, Jing; Yang, Yongying; Cheng, Zhongtao; Zhang, Yupeng; Zhou, Yudi; Duan, Lulin; Su, Lin

    2015-10-01

    High-spectral-resolution lidars (HSRLs) are increasingly being developed for atmospheric aerosol remote sensing applications due to the straightforward and independent retrieval of aerosol optical properties without reliance on assumptions about lidar ratio. In HSRL technique, spectral discrimination between scattering from molecules and aerosol particles is one of the most critical processes, which needs to be accomplished by means of a narrowband spectroscopic filter. To ensure a high retrieval accuracy of an HSRL system, the high-quality design of its spectral discrimination filter should be made. This paper reviews the available algorithms that were proposed for HSRLs and makes a general accuracy analysis of the HSRL technique focused on the spectral discrimination, in order to provide heuristic guidelines for the reasonable design of the spectral discrimination filter. We introduce a theoretical model for retrieval error evaluation of an HSRL instrument with general three-channel configuration. Monte Carlo (MC) simulations are performed to validate the correctness of the theoretical model. Results from both the model and MC simulations agree very well, and they illustrate one important, although not well realized fact: a large molecular transmittance and a large spectral discrimination ratio (SDR, i.e., ratio of the molecular transmittance to the aerosol transmittance) are beneficial t o promote the retrieval accuracy. The application of the conclusions obtained in this paper in the designing of a new type of spectroscopic filter, that is, the field-widened Michelson interferometer, is illustrated in detail. These works are with certain universality and expected to be useful guidelines for HSRL community, especially when choosing or designing the spectral discrimination filter.

  9. 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

  10. 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.

  11. Potentialities and Limits of ICESAT-2 Observation for Atmospheric Aerosol Investigation

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

    ICESat-2(Ice, Cloud, and land Elevation Satellite-2), slated for launch in 2017, will continue the important observations of ice-sheet elevation change, sea-ice freeboard, and vegetation canopy height begun by ICESat in 2003. Among the other potential applications, ICESat-2 could provide some information about atmospheric aerosol over Polar Regions thanks to the lidar instrument. In this context, it is essential to demonstrate the ICESat-2 capability of providing vertical profiles of the aerosol backscatter coefficient and to define its potentialities and limits. First results of this investigation are reported and will be presented at the conference.

  12. Seasonal Variations in Titan's Stratosphere Observed with Cassini/CIRS: Temperature, Trace Molecular Gas and Aerosol Mixing Ratio Profiles

    NASA Technical Reports Server (NTRS)

    Vinatier, S.; Bezard, B.; Anderson, C. M.; Coustenis, A.; Teanby, N.

    2012-01-01

    Titan's northern spring equinox occurred in August 2009. General Circulation Models (e.g. Lebonnois et al., 2012) predict strong modifications of the global circulation in this period, with formation of two circulation cells instead of the pole-to-pole cell that occurred during northern winter. This winter single cell, which had its descending branch at the north pole, was at the origin of the enrichment of molecular abundances and high stratopause temperatures observed by Cassini/CIRS at high northern latitudes (e.g. Achterberg et al., 2011, Coustenis et al., 2010, Teanby et al., 2008, Vinatier et al., 2010). The predicted dynamical seasonal variations after the equinox have strong impact on the spatial distributions of trace gas, temperature and aerosol abundances. We will present here an analysis of CIRS limb-geometry datasets acquired in 2010 and 2011 that we used to monitor the seasonal evolution of the vertical profiles of temperature, molecular (C2H2, C2H6, HCN, ..) and aerosol abundances.

  13. The Asian Tropopause Aerosol layer through satellite and balloon-borne measurements combined with modelling approaches.

    NASA Astrophysics Data System (ADS)

    Vernier, J. P.; Fairlie, T. D.; Natarajan, M.; Crawford, J. H.; Baker, N. C.; Wegner, T.; Deshler, T.; Gadhavi, H. S.; Kumar, S.; Singh, A. K.; Jayaraman, A.; Raj, A.; Alladi, H.; Ratnam, M. V.; Pandit, A.; Vignelles, D.; Wienhold, F.; Liu, H.; Kumar, S.

    2015-12-01

    The Asian tropopause Aerosol Layer (ATAL) is a seasonal aerosol feature occurring in the Upper Troposphere and Lower Stratosphere (UTLS) above Asia during the Summer Asian Monsoon. Vertically resolved aerosol backscatter profiles from the Cloud-Aerosol Lidar and Infrared Pathfinder satellite Observation (CALIPSO) mission and extinction profiles from the Stratospheric Aerosol and Gas Experiment (SAGE) have been used to infer the spatial and temporal distributions of the ATAL since the late 90's. We found that aerosol optical thickness between 13-18km have increased by a factor of 2-3 over the past 16 years likely related to raising pollution levels in South East Asia occuring during the same period. Modelling studies of the ATAL using WACCAM 3 and GEOS-Chem have provided conflicting information on its origin and a better representation of in-cloud SO2 and aerosol lifetime in GOES-Chem seems to be key to obtain consistent results with the few SO2 measurements available in the UTLS during the Asian Monsoon. In situ measurements of aerosol and trace gases in the UTLS from several balloon campaigns which took place in summer 2014 and 2015 in Asia will be presented and discussed with combined satellite and modelling analysis.

  14. Retrieving the height of smoke and dust aerosols by synergistic use of VIIRS, OMPS, and CALIOP observations

    NASA Astrophysics Data System (ADS)

    Lee, Jaehwa; Hsu, N. Christina; Bettenhausen, Corey; Sayer, Andrew M.; Seftor, Colin J.; Jeong, Myeong-Jae

    2015-08-01

    This study extends the application of the previously developed Aerosol Single-scattering albedo and layer Height Estimation (ASHE) algorithm, which was originally applied to smoke aerosols only, to both smoke and dust aerosols by including nonspherical dust properties in the retrieval process. The main purpose of the algorithm is to derive aerosol height information over wide areas using aerosol products from multiple satellite sensors simultaneously: aerosol optical depth (AOD) and Ångström exponent from the Visible Infrared Imaging Radiometer Suite (VIIRS), UV aerosol index from the Ozone Mapping and Profiler Suite (OMPS), and total backscatter coefficient profile from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP). The case studies suggest that the ASHE algorithm performs well for both smoke and dust aerosols, showing root-mean-square error of the retrieved aerosol height as compared to CALIOP observations from 0.58 to 1.31 km and mean bias from -0.70 to 1.13 km. In addition, the algorithm shows the ability to retrieve single-scattering albedo to within 0.03 of Aerosol Robotic Network inversion data for moderate to thick aerosol loadings (AOD of ~1.0). For typical single-layered aerosol cases, the estimated uncertainty in the retrieved height ranges from 1.20 to 1.80 km over land and from 1.15 to 1.58 km over ocean when favorable conditions are met. Larger errors are observed for multilayered aerosol events, due to the limited sensitivities of the passive sensors to such cases.

  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. 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.

  17. HARLIE 3-D Aerosol Backscatter and Wind Profile Measurements During Recent Field Experiments: Background Noise Reduction with a Fabry-Perot Etalon Filter in the HARLIE System

    NASA Technical Reports Server (NTRS)

    Lee, Sangwoo; Miller, David O.; Schwemmer, Geary; Wilkerson, Thomas D.; Andrus, Ionio; Egbert, Cameron; Anderson, Mark; Starr, David OC. (Technical Monitor)

    2002-01-01

    Background noise reduction of War signals is one of the most important factors in achieving better signal to noise ratio and precise atmospheric data from Mar measurements. Fahey Perot etalons have been used in several lidar systems as narrow band pass filters in the reduction of scattered sunlight. An slalom with spectral bandwidth, (Delta)v=0.23/cm, free spectral range, FSR=6.7/cm, and diameter, d=24mm was installed in a fiber coupled box which included a 500 pm bandwidth interference Filter. The slalom box couples the telescope and detector with 200 pm core fibers and 21 mm focal length collimators. The angular magnification is M=48. The etalon box was inserted into the Holographic Airborne Rotating Lidar Instrument Experiment (HARLIE) system and tested during the HARGLO-2 intercomparison campaign conducted in November 2001 at Wallops Island, Virginia. This paper presents the preliminary test results of the slalom and a complete analysis will be presented at the conference.

  18. Airborne water vapor DIAL system and measurements of water and aerosol profiles

    NASA Technical Reports Server (NTRS)

    Higdon, Noah S.; Browell, Edward V.

    1991-01-01

    The Lidar Applications Group at NASA Langley Research Center has developed a differential absorption lidar (DIAL) system for the remote measurement of atmospheric water vapor (H2O) and aerosols from an aircraft. The airborne H2O DIAL system is designed for extended flights to perform mesoscale investigations of H2O and aerosol distributions. This DIAL system utilizes a Nd:YAG-laser-pumped dye laser as the off-line transmitter and a narrowband, tunable Alexandrite laser as the on-line transmitter. The dye laser has an oscillator/amplifier configuration which incorporates a grating and prism in the oscillator cavity to narrow the output linewidth to approximately 15 pm. This linewidth can be maintained over the wavelength range of 725 to 730 nm, and it is sufficiently narrow to satisfy the off-line spectral requirements. In the Alexandrite laser, three intracavity tuning elements combine to produce an output linewidth of 1.1 pm. These spectral devices include a five-plate birefringent tuner, a 1-mm thick solid etalon and a 1-cm air-spaced etalon. A wavelength stability of +/- 0.35 pm is achieved by active feedback control of the two Fabry-Perot etalons using a frequency stabilized He-Ne laser as a wavelength reference. The three tuning elements can be synchronously scanned over a 150 pm range with microprocessor-based scanning electronics. Other aspects of the DIAL system are discussed.

  19. 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.

  20. Critical Evaluation of 0-30 km Profile Information in Ground-Based Zenith-Sky and Satellite-Measured Backscattered UV Radiation

    NASA Technical Reports Server (NTRS)

    Bhartia, Pawan; Petropavlovskikh, Irina; Deluishi, John; Einaudi, Franco (Technical Monitor)

    2000-01-01

    We now have several decades of experience in deriving vertical ozone profiles from the measurements of diffuse ultraviolet radiation by both ground and satellite-based instruments using Umkehr and BUV techniques. Continuing technological advances are pushing the state-of-the-art of these measurements to high spectral resolution and broader wavelength coverage. These modern instruments include the ground-based Brewer and satellite-based Global Ozone Monitoring Experiment (GOME) instruments, as well as advanced instruments being developed by ESA(SCIAMACHY), Netherlands(OMI) and Japan(ODUS). However, one of the issues that remains unresolved is the 0-30 km ozone profile information retrievable from these measurements. Though it is commonly believed that both the Umkehr and the satellite-based BUV techniques have very limited profile information below 30 km, there are those who argue that the data from these instruments should continue to be reported in this altitude range for they compare well with ozonesondes and hence there is useful scientific information. Others claim that the limitations of the Umkehr and BUV techniques are largely due to their low spectral resolution, and that the profile information below 30 km can be greatly improved by going to high spectral resolution instruments, such as Brewer and GOME. The purpose of this paper is to provide a critical evaluation of the 0-30 km ozone profile information in the various UV remote sensing techniques. We use a database of individual ozone profiles created using ozonesondes and SAGE and 4D ozone fields generated by data assimilation techniques to simulate radiances measured by the various techniques. We then apply a common inversion approach to all the methods to systematically examine how much profile information is available simply from the knowledge of total ozone, how much additional profile information is added by the traditional Dobson Umkehr and satellite buv techniques, and how much better one can do

  1. Validation of GOMOS-Envisat vertical profiles of O3, NO2, NO3, and aerosol extinction using balloon-borne instruments and analysis of the retrievals

    NASA Astrophysics Data System (ADS)

    Renard, Jean-Baptiste; Berthet, Gwenaël; Brogniez, Colette; Catoire, Valery; Fussen, Didier; Goutail, Florence; Oelhaf, Hermann; Pommereau, Jean-Pierre; Roscoe, Howard K.; Wetzel, Gerald; Chartier, Michel; Robert, Claude; Balois, Jean-Yves; Verwaerde, Christian; Auriol, Frédérique; François, Philippe; Gaubicher, Bertrand; Wursteisen, Patrick

    2008-02-01

    The UV-visible Global Ozone Monitoring by Occultation of Stars (GOMOS) instrument onboard Envisat performs nighttime measurements of ozone, NO2, NO3 and of the aerosol extinction, using the stellar occultation method. We have conducted a validation exercise using various balloon-borne instruments in different geophysical conditions from 2002 to 2006, using GOMOS measurements performed with stars of different magnitudes. GOMOS and balloon-borne vertical columns in the middle stratosphere are in excellent agreement for ozone and NO2. Some discrepancies can appear between GOMOS and balloon-borne vertical profiles for the altitude and the amplitude of the concentration maximum. These discrepancies are randomly distributed, and no bias is detected. The accuracy of individual profiles in the middle stratosphere is 10 % for ozone and 25 % for NO2. On the other hand, the GOMOS NO3 retrieval is difficult and no direct validation can be conducted. The GOMOS aerosol content is also well estimated, but the wavelength dependence can be better estimated if the aerosol retrieval is performed only in the visible domain. We can conclude that the GOMOS operational retrieval algorithm works well and that GOMOS has fully respected its primary objective for the study of the trends of species in the middle stratosphere, using the profiles in a statistical manner. Some individual profiles can be partly inaccurate, in particular in the lower stratosphere. Improvements could be obtained by reprocessing some GOMOS transmissions in case of specific studies in the middle and lower stratosphere when using the individual profiles.

  2. Vertical Profiles of Light-Absorbing Aerosol: A Combination of In-situ and AERONET Observations during NASA DISCOVER-AQ

    NASA Astrophysics Data System (ADS)

    Ziemba, L. D.; Beyersdorf, A. J.; Chen, G.; Corr, C.; Crumeyrolle, S.; Giles, D. M.; Holben, B. N.; Hudgins, C.; Martin, R.; Moore, R.; Shook, M.; Thornhill, K. L., II; Winstead, E.; Anderson, B. E.

    2014-12-01

    Understanding the vertical profile of atmospheric aerosols plays a vital role in utilizing spaceborne, column-integrated satellite observations. The properties and distribution of light-absorbing aerosol are particularly uncertain despite significant air quality and climate ramifications. Advanced retrieval algorithms are able to derive complex aerosol properties (e.g., wavelength-dependent absorption coefficient and single scattering albedo) from remote-sensing measurements, but quantitative relationships to surface conditions remain a challenge. Highly systematic atmospheric profiling during four unique deployments for the NASA DISCOVER-AQ project (Baltimore, MD, 2011; San Joaquin Valley, CA, 2013; Houston, TX, 2013; Denver, CO, 2014) allow statistical assessment of spatial, temporal, and source-related variability for light-absorbing aerosol properties in these distinct regions. In-situ sampling in conjunction with a dense network of AERONET sensors also allows evaluation of the sensitivity, limitations, and advantages of remote-sensing data products over a wide range of conditions. In-situ aerosol and gas-phase observations were made during DISCOVER-AQ aboard the NASA P-3B aircraft. Aerosol absorption coefficients were measured by a Particle Soot Absorption Photometer (PSAP). Approximately 200 profiles for each of the four deployments were obtained, from the surface (25-300m altitude) to 5 km, and are used to calculate absorption aerosol optical depths (AAODs). These are quantitatively compared to AAOD derived from AERONET Level 1.5 retrievals to 1) explore discrepancies between measurements, 2) quantify the fraction of AAOD that exists directly at the surface and is often missed by airborne sampling, and 3) evaluate the potential for deriving ground-level black carbon (BC) concentrations for air quality prediction. Aerosol size distributions are used to assess absorption contributions from mineral dust, both at the surface and aloft. SP2 (Single Particle Soot

  3. Dependence of the drizzle growth process on the cloud top height and its relevance to the aerosol vertical profile

    NASA Astrophysics Data System (ADS)

    Kawamoto, K.; Suzuki, K.

    2013-12-01

    Transitional processes among cloud droplets, drizzle and raindrops are still uncertain and more efforts are required for the better understanding. In this situation, difference in the drizzle growth process was examined according to the cloud top height using the CloudSat and MODIS synergetic datasets. From the CloudSat products such as 2B-GEOPROF, 2B-TAU, ECMWF-AUX, only one-layered water clouds whose top temperatures were warmer than 273K were extracted over China (a circular area having a diameter of 1800km of the center at 35°N and 120°E) and over ocean (a circular area having a diameter of 1500km of the center at 35°N and 150°E). Then a threshold of 3km of the cloud top height was adopted to divide the extracted clouds into upper and lower cases. First, the probability distribution functions (PDF) of the cloud droplet number density (Nc) and the effective particle radius (Re) were calculated for these four cases (land/ocean/upper/lower). Nc was obtained assuming the adiabatic liquid water content from MODIS-derived cloud optical depth and Re. Oceanic clouds had fewer Nc than land clouds, and almost the same for upper and lower cases. Land clouds had more Nc for the lower case than for the higher case. On the other hand, oceanic clouds had larger Re than land clouds, and almost the same for upper and lower cases. Land clouds had smaller Re for the lower case than for the higher case. These results quite agreed with our existing knowledge on the vertical profile of the aerosol number concentration over ocean (pristine) and land (polluted). Although the number of aerosol particles is fewer and almost the same regardless of the height over the ocean, it is more near the surface and it rapidly decreases according to the height over the land. Next, examining PDF of the radar reflectivity (Ze), we found that although PDFs of Ze were almost the same for oceanic clouds regardless of the cloud top height, PDF of land lower clouds were less frequent at around from

  4. A statistical inference approach for the retrieval of the atmospheric ozone profile from simulated satellite measurements of solar backscattered ultraviolet radiation

    NASA Technical Reports Server (NTRS)

    Bonavito, N. L.; Gordon, C. L.; Inguva, R.; Serafino, G. N.; Barnes, R. A.

    1994-01-01

    NASA's Mission to Planet Earth (MTPE) will address important interdisciplinary and environmental issues such as global warming, ozone depletion, deforestation, acid rain, and the like with its long term satellite observations of the Earth and with its comprehensive Data and Information System. Extensive sets of satellite observations supporting MTPE will be provided by the Earth Observing System (EOS), while more specific process related observations will be provided by smaller Earth Probes. MTPE will use data from ground and airborne scientific investigations to supplement and validate the global observations obtained from satellite imagery, while the EOS satellites will support interdisciplinary research and model development. This is important for understanding the processes that control the global environment and for improving the prediction of events. In this paper we illustrate the potential for powerful artificial intelligence (AI) techniques when used in the analysis of the formidable problems that exist in the NASA Earth Science programs and of those to be encountered in the future MTPE and EOS programs. These techniques, based on the logical and probabilistic reasoning aspects of plausible inference, strongly emphasize the synergetic relation between data and information. As such, they are ideally suited for the analysis of the massive data streams to be provided by both MTPE and EOS. To demonstrate this, we address both the satellite imagery and model enhancement issues for the problem of ozone profile retrieval through a method based on plausible scientific inferencing. Since in the retrieval problem, the atmospheric ozone profile that is consistent with a given set of measured radiances may not be unique, an optimum statistical method is used to estimate a 'best' profile solution from the radiances and from additional a priori information.

  5. Influence of atmospheric parameters on vertical profiles and horizontal transport of aerosols generated in the surf zone

    NASA Astrophysics Data System (ADS)

    Kusmierczyk-Michulec, J.; Tedeschi, G.; Van Eijk, A. M. J.; Piazzola, J.

    2013-10-01

    The vertical and horizontal transport of aerosols generated over the surf zone is discussed. Experimental data were collected during the second campaign of the Surf Zone Aerosol Experiment that took place in Duck NC (USA) in November 2007. The Empirical Orthogonal Function (EOF) method was used to analyze the vertical concentration gradients, and allowed separating the surf aerosols from aerosols advected from elsewhere. The numerical Marine Aerosol Concentration Model (MACMod) supported the analysis by confirming that the concentration gradients are more pronounced under stable conditions and that aerosol plumes are then more confined to the surface. The model also confirmed the experimental observations made during two boat runs along the offshore wind vector that surf-generated aerosols are efficiently advected out to sea over several tens of kilometers.

  6. A compact mobile ozone lidar for atmospheric ozone and aerosol profiling

    NASA Astrophysics Data System (ADS)

    De Young, Russell; Carrion, William; Pliutau, Denis

    2014-10-01

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

  7. A Compact Mobile Ozone Lidar for Atmospheric Ozone and Aerosol Profiling

    NASA Technical Reports Server (NTRS)

    De Young, Russell; Carrion, William; Pliutau, Denis

    2014-01-01

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

  8. High spectral resolution lidar to measure optical scattering properties of atmospheric aerosols. I - Theory and instrumentation

    NASA Technical Reports Server (NTRS)

    Shipley, S. T.; Tracy, D. H.; Eloranta, E. W.; Roesler, F. L.; Weinman, J. A.; Trauger, J. T.; Sroga, J. T.

    1983-01-01

    A high spectral resolution lidar technique to measure optical scattering properties of atmospheric aerosols is described. Light backscattered by the atmosphere from a narrowband optically pumped oscillator-amplifier dye laser is separated into its Doppler broadened molecular and elastically scattered aerosol components by a two-channel Fabry-Perot polyetalon interferometer. Aerosol optical properties, such as the backscatter ratio, optical depth, extinction cross section, scattering cross section, and the backscatter phase function, are derived from the two-channel measurements.

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

    NASA Astrophysics Data System (ADS)

    Young, Joseph Swyler

    This thesis investigates the utility of lidar ceilometers, a type of aerosol lidar, in improving the understanding of meteorology and air quality in persistent wintertime stable boundary layers, or cold-air pools, that form in urbanized valley and basin topography. This thesis reviews the scientific literature to survey the present knowledge of persistent cold-air pools, the operating principles of lidar ceilometers, and their demonstrated utility in meteorological investigations. Lidar ceilometer data from the Persistent Cold-Air Pool Study (PCAPS) are then used with meteorological and air quality data from other in situ and remote sensing equipment to investigate cold-air pools that formed in Utah's Salt Lake Valley during the winter of 2010-2011. The lidar ceilometer is shown to accurately measure aerosol layer depth and aerosol loading, when compared to visual observations. A linear relationship is found between low-level lidar backscatter and surface particulate measurements. Convective boundary layer lidar analysis techniques applied to cold-air pool ceilometer profiles can detect useful layer characteristics. Fine-scale waves are observed and analyzed within the aerosol layer, with emphasis on Kelvin-Helmholz waves. Ceilometer aerosol backscatter profiles are analyzed to quantify and describe mixing processes in persistent cold-air pools. Overlays of other remote and in-situ observations are combined with ceilometer particle backscatter to describe specific events during PCAPS. This analysis describes the relationship between the aerosol layer and the valley inversion as well as interactions with large-scale meteorology. The ceilometer observations of hydrometers are used to quantify cloudiness and precipitation during the project, observing that 50% of hours when a PCAP was present had clouds or precipitation below 5 km above ground level (AGL). Then, combining an objective technique for determining hourly aerosol layer depths and correcting this

  10. Software for retrieving the ozone altitude profiles from data of atmospheric laser sensing

    NASA Astrophysics Data System (ADS)

    Nevzorov, Aleksey V.; Nevzorov, Aleksey A.; Romanovskii, Oleg A.

    2014-11-01

    In the report, we describe the software developed to retrieve the ozone altitude profiles from data of lidar measurements. The software is written in the programming language R#. At present, the C# language is one of the most advanced and modern programming languages. Many programs are written in this language since it is very easy to understand. The software makes it possible to calculate the ozone altitude profiles according to the method of differential absorption and scattering for three wavelength pairs 272/289 nm, 299/341 nm, and 308/353 nm. These wavelength pairs were chosen in view of the availability of lidar measurement data. The software has a suitable graphical interface, which displays all the steps of retrieving the ozone profiles in real time. The software makes it possible: to read off the lidar data and write the retrieval results in ASCII format; and smooth the lidar signals and the retrieval results with sliding averaging. The temperature correction of zone absorption coefficients is introduced in the software to reduce the retrieval errors. The aerosol backscattering is several times stronger than molecular backscattering when aerosol loading of the atmosphere is large; therefore, the retrieved ozone profile is substantially distorted when the scattering and attenuating properties of the atmosphere at the sensing wavelengths are not taken into consideration. An aerosol correction is introduced in this software. The latitudinally average seasonal model values of the altitudinal distribution of temperature and molecular backscattering coefficient for winter and summer are introduced in the software for the calculation.

  11. Transcriptional Profiling of the Circulating Immune Response to Lassa Virus in an Aerosol Model of Exposure

    PubMed Central

    Honko, Anna N.; Garamszegi, Sara; Caballero, Ignacio S.; Johnson, Joshua C.; Mucker, Eric M.; Trefry, John C.; Hensley, Lisa E.; Connor, John H.

    2013-01-01

    Lassa virus (LASV) is a significant human pathogen that is endemic to several countries in West Africa. Infection with LASV leads to the development of hemorrhagic fever in a significant number of cases, and it is estimated that thousands die each year from the disease. Little is known about the complex immune mechanisms governing the response to LASV or the genetic determinants of susceptibility and resistance to infection. In the study presented here, we have used a whole-genome, microarray-based approach to determine the temporal host response in the peripheral blood mononuclear cells (PBMCs) of non-human primates (NHP) following aerosol exposure to LASV. Sequential sampling over the entire disease course showed that there are strong transcriptional changes of the immune response to LASV exposure, including the early induction of interferon-responsive genes and Toll-like receptor signaling pathways. However, this increase in early innate responses was coupled with a lack of pro-inflammatory cytokine response in LASV exposed NHPs. There was a distinct lack of cytokines such as IL1β and IL23α, while immunosuppressive cytokines such as IL27 and IL6 were upregulated. Comparison of IRF/STAT1-stimulated gene expression with the viral load in LASV exposed NHPs suggests that mRNA expression significantly precedes viremia, and thus might be used for early diagnostics of the disease. Our results provide a transcriptomic survey of the circulating immune response to hemorrhagic LASV exposure and provide a foundation for biomarker identification to allow clinical diagnosis of LASV infection through analysis of the host response. PMID:23638192

  12. An overview on the use of backscattered sound for measuring suspended particle size and concentration profiles in non-cohesive inorganic sediment transport studies

    NASA Astrophysics Data System (ADS)

    Thorne, Peter D.; Hurther, David

    2014-02-01

    For over two decades, coastal marine scientists studying boundary layer sediment transport processes have been using, and developing, the application of sound for high temporal-spatial resolution measurements of suspended particle size and concentration profiles. To extract the suspended sediment parameters from the acoustic data requires an understanding of the interaction of sound with a suspension of sediments and an inversion methodology. This understanding is distributed around journals in a number of scientific fields and there is no single article that succinctly draws together the different components. In the present work the aim is to provide an overview on the acoustic approach to measuring suspended sediment parameters and assess its application in the study of non-cohesive inorganic suspended sediment transport processes.

  13. Vertical distribution of aerosol optical properties based on aircraft measurements over the Loess Plateau in China.

    PubMed

    Li, Junxia; Liu, Xingang; Yuan, Liang; Yin, Yan; Li, Zhanqing; Li, Peiren; Ren, Gang; Jin, Lijun; Li, Runjun; Dong, Zipeng; Li, Yiyu; Yang, Junmei

    2015-08-01

    Vertical distributions of aerosol optical properties based on aircraft measurements over the Loess Plateau were measured for the first time during a summertime aircraft campaign, 2013 in Shanxi, China. Data from four flights were analyzed. The vertical distributions of aerosol optical properties including aerosol scattering coefficients (σsc), absorption coefficients (σab), Angström exponent (α), single scattering albedo (ω), backscattering ratio (βsc), aerosol mass scattering proficiency (Qsc) and aerosol surface scattering proficiency (Qsc(')) were obtained. The mean statistical values of σsc were 77.45 Mm(-1) (at 450 nm), 50.72 Mm(-1) (at 550n m), and 32.02 Mm(-1) (at 700 nm). The mean value of σab was 7.62 Mm(-1) (at 550 nm). The mean values of α, βsc and ω were 1.93, 0.15, and 0.91, respectively. Aerosol concentration decreased with altitude. Most effective diameters (ED) of aerosols were less than 0.8 μm. The vertical profiles of σsc,, α, βsc, Qsc and Qsc(') showed that the aerosol scattering properties at lower levels contributed the most to the total aerosol radiative forcing. Both α and βsc had relatively large values, suggesting that most aerosols in the observational region were small particles. The mean values of σsc, α, βsc, Qsc, Qsc('), σab and ω at different height ranges showed that most of the parameters decreased with altitude. The forty-eight hour backward trajectories of air masses during the observation days indicated that the majority of aerosols in the lower level contributed the most to the total aerosol loading, and most of these particles originated from local or regional pollution emissions. PMID:26257345

  14. Radar backscatter modelling

    NASA Technical Reports Server (NTRS)

    Schaber, G. G.; Kozak, R. C.; Gurule, R. L.

    1984-01-01

    The terrain analysis software package was restructured and documentation was added. A program was written to test Johnson Space Center's four band scatterometer data for spurious signals data. A catalog of terrain roughness statistics and calibrated four frequency multipolarization scatterometer data is being published to support the maintenance of Death Valley as a radar backscatter calibration test site for all future airborne and spacecraft missions. Test pits were dug through sand covered terrains in the Eastern Sahara to define the depth and character of subsurface interfaces responsible for either backscatter or specular response in SIR-A imagery. Blocky sandstone bedrock surfaces at about 1 m depth were responsible for the brightest SIR-A returns. Irregular very dense CaCO3 cemented sand interfaces were responsible for intermediate grey tones. Ancient river valleys had the weakest response. Reexamination of SEASAT l-band imagery of U.S. deserts continues.

  15. 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.

  16. Development of global model for atmospheric backscatter at CO2 wavelengths

    NASA Astrophysics Data System (ADS)

    Kent, G. S.; Wang, P. H.; Farrukh, U.; Deepak, A.; Patterson, E. M.

    1985-03-01

    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.

  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. Space Borne Cloud and Aerosol Measurements by the Geoscience Laser Altimeter System: Initial Results

    NASA Technical Reports Server (NTRS)

    Spinhirne, James D.; Palm, Steven P.; Hlavka, Dennis L.; Hart, William D.; Mahesh, Ashwin; Welton, Ellsworth J.

    2003-01-01

    In January 2003 the Geoscience Laser Altimeter System (GLAS) was successfully launched into orbit. Beginning in March 2003 GLAS will provide global coverage lidar measurement of the height distribution of clouds and aerosol in the atmosphere for up to five years. The characteristic and value of the unique data will be presented. The instrument is a basic backscatter lidar that operates at two wavelengths, 532 and 1064 nm. The mission data products for atmospheric observations include the calibrated, observed, attenuated backscatter cross section for cloud and aerosol; height detection for multiple cloud layers; planetary boundary layer height; cirrus and aerosol optical depth and the height distribution of aerosol and cloud scattering cross section profiles. The data is expected to significantly enhance knowledge in several areas of atmospheric science, in particular the distribution, transport and influence of atmospheric aerosol and thin clouds. Measurements of the coverage and height of polar and cirrus cloud should be significantly more accurate than previous global observations. In March and April 2003, airborne and ground based data verification experiments will be carried out. Initial results from the verification experiments and the first several months of operation will be presented.

  19. Ground-Based Lidar Measurements of Aerosols During ACE-2 Instrument Description, Results, and Comparisons with Other Ground-Based and Airborne Measurements

    NASA Technical Reports Server (NTRS)

    Welton, Ellsworth J.; Voss, Kenneth J.; Gordon, Howard R.; Maring, Hal; Smirnov, Alexander; Holben, Brent; Schmid, Beat; Livingston, John M.; Russell, Philip B.; Durkee, Philip A.; Formenti, Paolo

    2000-01-01

    A micro-pulse lidar system (MPL) was used to measure the vertical and horizontal distribution or aerosols during the Aerosol Characterization Experiment 2 (ACE-2) in June and July of 1997. The MPL measurements were made at the Izana observatory (IZO), a weather station located on a mountain ridge (28 deg 18'N, 16 deg 30'W, 2367 m asl) near the center of the island of Tenerife, Canary Islands. The MPL was used to acquire aerosol backscatter, extinction, and optical depth profiles for normal background periods and periods influenced by Saharan dust from North Africa. System tests and calibration procedures are discussed, and in analysis of aerosol optical profiles acquired during ACE-2 is presented. MPL data taken during normal IZO conditions (no dust) showed that upslope aerosols appeared during the day and dissipated at night and that the layers were mostly confined to altitudes a few hundred meters above IZO. MPL data taken during a Saharan dust episode on 17 July showed that peak aerosol extinction values were an order of magnitude greater than molecular scattering over IZO. and that the dust layers extended to 5 km asl. The value of the dust backscatter-extinction ratio was determined to be 0.027 + 0.007 per sr. Comparisons of the MPL data with data from other co-located instruments showed good agreement during the dust episode.

  20. Ground-Based Lidar Measurements of Aerosols During ACE-2: Instrument Description, Results, and Comparisons with Other Ground-Based and Airborne Measurements

    NASA Technical Reports Server (NTRS)

    Welton, Ellsworth J.; Voss, Kenneth J.; Gordon, Howard R.; Maring, Hal; Smirnov, Alexander; Holben, Brent; Schmid, Beat; Livingston, John M.; Russell, Philip B.; Durkee, Philip A.

    2000-01-01

    A micro-pulse lidar system (MPL) was used to measure the vertical and horizontal distribution of aerosols during the Aerosol Characterization Experiment 2 (ACE-2) in June and July of 1997. The MPL measurements were made at the Izana observatory (IZO), a weather station located on a mountain ridge (28 deg 18 min N, 16 deg 30 min W, 2367 m asl) near the center of the island of Tenerife, Canary Islands. The MPL was used to acquire aerosol backscatter, extinction, and optical depth profiles for normal background periods and periods influenced by Saharan dust from North Africa. System tests and calibration procedures are discussed, and an analysis of aerosol optical profiles acquired during ACE-2 is presented. MPL data taken during normal IZO conditions (no dust) showed that upslope aerosols appeared during the day and dissipated at night and that the layers were mostly confined to altitudes a few hundred meters above IZO. MPL data taken during a Saharan dust episode on 17 July showed that peak aerosol extinction values were an order of magnitude greater than molecular scattering over IZO, and that the dust layers extended to 5 km asl. The value of the dust backscatter-extinction ratio was determined to be 0.027 +/- 0.007 sr(exp -1). Comparisons of the MPL data with data from other collocated instruments showed good agreement during the dust episode.

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

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

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

  2. Estimating Mixing Heights Using Microwave Temperature Profiler

    NASA Technical Reports Server (NTRS)

    Nielson-Gammon, John; Powell, Christina; Mahoney, Michael; Angevine, Wayne

    2008-01-01

    A paper describes the Microwave Temperature Profiler (MTP) for making measurements of the planetary boundary layer thermal structure data necessary for air quality forecasting as the Mixing Layer (ML) height determines the volume in which daytime pollution is primarily concentrated. This is the first time that an airborne temperature profiler has been used to measure the mixing layer height. Normally, this is done using a radar wind profiler, which is both noisy and large. The MTP was deployed during the Texas 2000 Air Quality Study (TexAQS-2000). An objective technique was developed and tested for estimating the ML height from the MTP vertical temperature profiles. In order to calibrate the technique and evaluate the usefulness of this approach, estimates from a variety of measurements during the TexAQS-2000 were compared. Estimates of ML height were used from radiosondes, radar wind profilers, an aerosol backscatter lidar, and in-situ aircraft measurements in addition to those from the MTP.

  3. A method for removing arm backscatter from EPID images

    SciTech Connect

    King, Brian W.; Greer, Peter B.

    2013-07-15

    Purpose: To develop a method for removing the support arm backscatter from images acquired using current Varian electronic portal imaging devices (EPIDs).Methods: The effect of arm backscatter on EPID images was modeled using a kernel convolution method. The parameters of the model were optimized by comparing on-arm images to off-arm images. The model was used to develop a method to remove the effect of backscatter from measured EPID images. The performance of the backscatter removal method was tested by comparing backscatter corrected on-arm images to measured off-arm images for 17 rectangular fields of different sizes and locations on the imager. The method was also tested using on- and off-arm images from 42 intensity modulated radiotherapy (IMRT) fields.Results: Images generated by the backscatter removal method gave consistently better agreement with off-arm images than images without backscatter correction. For the 17 rectangular fields studied, the root mean square difference of in-plane profiles compared to off-arm profiles was reduced from 1.19% (standard deviation 0.59%) on average without backscatter removal to 0.38% (standard deviation 0.18%) when using the backscatter removal method. When comparing to the off-arm images from the 42 IMRT fields, the mean {gamma} and percentage of pixels with {gamma} < 1 were improved by the backscatter removal method in all but one of the images studied. The mean {gamma} value (1%, 1 mm) for the IMRT fields studied was reduced from 0.80 to 0.57 by using the backscatter removal method, while the mean {gamma} pass rate was increased from 72.2% to 84.6%.Conclusions: A backscatter removal method has been developed to estimate the image acquired by the EPID without any arm backscatter from an image acquired in the presence of arm backscatter. The method has been shown to produce consistently reliable results for a wide range of field sizes and jaw configurations.

  4. 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.

  5. Inversion of tropospheric profiles of aerosol extinction and HCHO and NO2 mixing ratios from MAX-DOAS observations in Milano during the summer of 2003 and comparison with independent data sets

    NASA Astrophysics Data System (ADS)

    Wagner, T.; Beirle, S.; Brauers, T.; Deutschmann, T.; Frieß, U.; Hak, C.; Halla, J. D.; Heue, K. P.; Junkermann, W.; Li, X.; Platt, U.; Pundt-Gruber, I.

    2011-12-01

    We present aerosol and trace gas profiles derived from MAX-DOAS observations. Our inversion scheme is based on simple profile parameterisations used as input for an atmospheric radiative transfer model (forward model). From a least squares fit of the forward model to the MAX-DOAS measurements, two profile parameters are retrieved including integrated quantities (aerosol optical depth or trace gas vertical column density), and parameters describing the height and shape of the respective profiles. From these results, the aerosol extinction and trace gas mixing ratios can also be calculated. We apply the profile inversion to MAX-DOAS observations during a measurement campaign in Milano, Italy, September 2003, which allowed simultaneous observations from three telescopes (directed to north, west, south). Profile inversions for aerosols and trace gases were possible on 23 days. Especially in the middle of the campaign (17-20 September 2003), enhanced values of aerosol optical depth and NO2 and HCHO mixing ratios were found. The retrieved layer heights were typically similar for HCHO and aerosols. For NO2, lower layer heights were found, which increased during the day. The MAX-DOAS inversion results are compared to independent measurements: (1) aerosol optical depth measured at an AERONET station at Ispra; (2) near-surface NO2 and HCHO (formaldehyde) mixing ratios measured by long path DOAS and Hantzsch instruments at Bresso; (3) vertical profiles of HCHO and aerosols measured by an ultra light aircraft. Depending on the viewing direction, the aerosol optical depths from MAX-DOAS are either smaller or larger than those from AERONET observations. Similar comparison results are found for the MAX-DOAS NO2 mixing ratios versus long path DOAS measurements. In contrast, the MAX-DOAS HCHO mixing ratios are generally higher than those from long path DOAS or Hantzsch instruments. The comparison of the HCHO and aerosol profiles from the aircraft showed reasonable agreement with

  6. Inversion of tropospheric profiles of aerosol extinction and HCHO and NO2 mixing ratios from MAX-DOAS observations in Milano during the summer of 2003 and comparison with independent data sets

    NASA Astrophysics Data System (ADS)

    Wagner, T.; Beirle, S.; Brauers, T.; Deutschmann, T.; Frieß, U.; Hak, C.; Halla, J. D.; Heue, K. P.; Junkermann, W.; Li, X.; Platt, U.; Pundt-Gruber, I.

    2011-06-01

    We present aerosol and trace gas profiles derived from MAX-DOAS observations. Our inversion scheme is based on simple profile parameterisations used as input for an atmospheric radiative transfer model (forward model). From a least squares fit of the forward model to the MAX-DOAS measurements, two profile parameters are retrieved including integrated quantities (aerosol optical depth or trace gas vertical column density), and parameters describing the height and shape of the respective profiles. From these results, the aerosol extinction and trace gas mixing ratios can also be calculated. We apply the profile inversion to MAX-DOAS observations during a measurement campaign in Milano, Italy, September 2003, which allowed simultaneous observations from three telescopes (directed to north, west, south). Profile inversions for aerosols and trace gases were possible on 23 days. Especially in the middle of the campaign (17-20 September 2003), enhanced values of aerosol optical depth and NO2 and HCHO mixing ratios were found. The retrieved layer heights were typically similar for HCHO and aerosols. For NO2, lower layer heights were found, which increased during the day. The MAX-DOAS inversion results are compared to independent measurements: (1) aerosol optical depth measured at an AERONET station at Ispra; (2) near-surface NO2 and HCHO (formaldehyde) mixing ratios measured by long path DOAS and Hantzsch instruments at Bresso; (3) vertical profiles of HCHO and aerosols measured by an ultra light aircraft. Depending on the viewing direction, the aerosol optical depths from MAX-DOAS are either smaller or larger than those from AERONET observations. Similar comparison results are found for the MAX-DOAS NO2 mixing ratios versus long path DOAS measurements. In contrast, the MAX-DOAS HCHO mixing ratios are generally higher than those from long path DOAS or Hantzsch instruments. The comparison of the HCHO and aerosol profiles from the aircraft showed reasonable agreement with

  7. Demonstration of Aerosol Property Profiling by Multiwavelength Lidar Under Varying Relative Humidity Conditions

    NASA Technical Reports Server (NTRS)

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

    2009-01-01

    During the months of July-August 2007 NASA conducted a research campaign called the Tropical Composition, Clouds and Climate Coupling (TC4) experiment. Vertical profiles of ozone were measured daily using an instrument known as an ozonesonde, which is attached to a weather balloon and launch to altitudes in excess of 30 km. These ozone profiles were measured over coastal Las Tablas, Panama (7.8N, 80W) and several times per week at Alajuela, Costa Rica (ION, 84W). Meteorological systems in the form of waves, detected most prominently in 100-300 in thick ozone layer in the tropical tropopause layer, occurred in 50% (Las Tablas) and 40% (Alajuela) of the soundings. These layers, associated with vertical displacements and classified as gravity waves ("GW," possibly Kelvin waves), occur with similar stricture and frequency over the Paramaribo (5.8N, 55W) and San Cristobal (0.925, 90W) sites of the Southern Hemisphere Additional Ozonesondes (SHADOZ) network. The gravity wave labeled layers in individual soundings correspond to cloud outflow as indicated by the tracers measured from the NASA DC-8 and other aircraft data, confirming convective initiation of equatorial waves. Layers representing quasi-horizontal displacements, referred to as Rossby waves, are robust features in soundings from 23 July to 5 August. The features associated with Rossby waves correspond to extra-tropical influence, possibly stratospheric, and sometimes to pollution transport. Comparison of Las Tablas and Alajuela ozone budgets with 1999-2007 Paramaribo and San Cristobal soundings shows that TC4 is typical of climatology for the equatorial Americas. Overall during TC4, convection and associated meteorological waves appear to dominate ozone transport in the tropical tropopause layer.

  8. Assessment of the CALIPSO Lidar 532 nm Attenuated Backscatter Calibration Using the NASA LaRC Airborne High Spectral Resolution Lidar

    NASA Technical Reports Server (NTRS)

    Rogers, Raymond R.; Hostetler, Chris A.; Hair, Johnathan W.; Ferrare, Richard A.; Liu, Zhaoyan; Obland, Michael D.; Harper, David B.; Cook, Anthony L.; Powell, Kathleen A.; Vaughan, Mark A.; Winker, David M.

    2011-01-01

    The Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) instrument on the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) spacecraft has provided global, high-resolution vertical profiles of aerosols and clouds since it became operational on 13 June 2006. On 14 June 2006, the NASA Langley Research Center (LaRC) High Spectral Resolution Lidar (HSRL) was deployed aboard the NASA Langley B-200 aircraft for the first of a series of 86 underflights of the CALIPSO satellite to provide validation measurements for the CALIOP data products. To better assess the range of conditions under which CALIOP data products are produced, these validation flights were conducted under both daytime and nighttime lighting conditions, in multiple seasons, and over a large range of latitudes and aerosol and cloud conditions. This paper presents a quantitative assessment of the CALIOP 532 nm calibration (through the 532 nm total attenuated backscatter) using an internally calibrated airborne HSRL underflight data and is the most extensive study of CALIOP 532 nm calibration. Results show that average HSRL and CALIOP 532 nm total attenuated backscatter agree on average within 2.7% +/- 2.1% (CALIOP lower) at night and within 2.9 % +/- 3.9% (CALIOP lower) during the day., demonstrating the accuracy of the CALIOP 532 nm calibration algorithms. Additionally, comparisons with HSRL show consistency of the CALIOP calibration before and after the laser switch in 2009 as well as improvements in the daytime version 3 calibration scheme compared with the version 2 calibration scheme. Potential systematic uncertainties in the methodology relevant to validating satellite lidar measurements with an airborne lidar system are discussed and found to be less than 3.7% for this validation effort with HSRL. Results from this study are also compared to those from prior assessments of CALIOP calibration and attenuated backscatter.

  9. Spaceborne lidar measurement accuracy - Simulation of aerosol, cloud, molecular density, and temperature retrievals

    NASA Technical Reports Server (NTRS)

    Russell, P. B.; Morley, B. M.; Browell, E. V.

    1982-01-01

    In connection with studies concerning the use of an orbiting optical radar (lidar) to conduct aerosol and cloud measurements, attention has been given to the accuracy with which lidar return signals could be measured. However, signal-measurement error is not the only source of error which can affect the accuracy of the derived information. Other error sources are the assumed molecular-density and atmospheric-transmission profiles, and the lidar calibration factor (which relates signal to backscatter coefficient). The present investigation has the objective to account for the effects of all these errors sources for several realistic combinations of lidar parameters, model atmospheres, and background lighting conditions. In addition, a procedure is tested and developed for measuring density and temperature profiles with the lidar, and for using the lidar-derived density profiles to improve aerosol retrievals.

  10. Spatial variation of stratospheric aerosol acidity and model refractive index - Implications of recent results

    NASA Technical Reports Server (NTRS)

    Russell, P. B.; Hamill, P.

    1984-01-01

    Recent experimental results indicate that little or no solid ammonium sulfate is present in background stratospheric aerosols. Other results allow straightforward calculation of sulfuric acid/water droplet properties (acidity, specific gravity, refractive index) as functions of stratospheric temperature and humidity. These results are combined with a variety of latitudinal and seasonal temperature and humidity profiles to obtain corresponding profiles of droplet properties. These profiles are used to update a previous model of stratospheric aerosol refractive index. The new model retains the simplifying approximation of vertically constant refractive index in the inner stratosphere, but has sulfuric acid/water refractive index values that significantly exceed the previously used room temperature values. Mean conversion ratios (e.g., extinction-to-number, backscatter-to-volume) obtained using Mie scattering calculations with the new refractive indices are very similar to those obtained for the old indices, because the effects of deleting ammonium sulfate and increasing acid indices tend to cancel each other.

  11. 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.

  12. Measurements of Vertical Profiles of Turbulence, Temperature, Ozone, Aerosols, and BrO over Sea Ice and Tundra Snowpack during BROMEX

    NASA Astrophysics Data System (ADS)

    Shepson, P.; Caulton, D.; Cambaliza, M. L.; Dhaniyala, S.; Fuentes, J. D.; General, S.; Halfacre, J. W.; Nghiem, S. V.; Perez Perez, L.; Peterson, P. K.; Platt, U.; Pohler, D.; Pratt, K. A.; Simpson, W. R.; Stirm, B.; Walsh, S. J.; Zielcke, J.

    2012-12-01

    During the BROMEX field campaign of March 2012, we conducted measurements of boundary layer structure, ozone, BrO and aerosol, from a light, twin-engine aircraft during eleven flights originating from Barrow, AK. Flights were conducted over the sea ice in the Beaufort and Chukchi Seas, and over the tundra from Barrow to the Brooks Range, with vertical profiles covering altitudes from the surface to 3.5km in the free troposphere. Flights over the course of one month allowed a variety of sea ice conditions, including open water, nilas, first year sea ice, and frost flowers, to be examined over the Chukchi Sea. Atmospheric turbulence was measured using a calibrated turbulence probe, which will enable characterization of both the structure and turbulence of the Arctic boundary layer. Ozone was measured using a 2B UV absorption instrument. A GRIMM optical particle counter was used to measure 0.25-4 μm sized aerosol particles. The MAX-DOAS instrument enabled measurements of BrO vertical profiles. The aircraft measurements can be used to connect the surface measurements of ozone and BrO from the "Icelander" buoys, and the surface sites at Barrow, with those measured on the aircraft. Here we will discuss the spatial variability/coherence in these data. A major question that will be addressed using these data is the extent to which bromine is activated through reactions at the snowpack/ice surface versus the surface of aerosols. Here we will present a preliminary analysis of the relationships between snow/ice surface types, aerosol size-resolved number concentrations, and the vertical profiles of ozone and BrO.

  13. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2003-07-01

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

  15. Broadband stimulated Raman backscattering

    NASA Astrophysics Data System (ADS)

    Landgraf, B.; Aurand, B.; Lehmann, G.; Gangolf, T.; Schnell, M.; Kühl, T.; Spielmann, C.

    2016-07-01

    Broadband amplification employing stimulated Raman backscattering is demonstrated. Using seed pulses with a bandwidth of about 200 nm, we study the amplification in a wide spectral range in a single laser shot. With chirped pump pulses and a Ne gas jet, we observed under optimized conditions, amplification in a range of about 80 nm, which is sufficient to support the amplification of sub-20 fs pulses. This broad amplification range is also in excellent agreement with PIC simulations. The conversion efficiency is at certain wavelengths as high as 1.2% and was measured to be better than 6 × 10‑3 on average.

  16. Statistical variations of ultrasound signals backscattered from flowing blood.

    PubMed

    Huang, Chih-Chung; Wang, Shyh-Hau

    2007-12-01

    The statistical distributions of ultrasonic signals backscattered from blood have recently been used to characterize hemodynamic properties, such as red blood cell (RBC) aggregation and blood coagulation. However, a thorough understanding of the relationship between blood properties and the statistical behavior of signals backscattered from flowing blood is still lacking. This prompted us to use the statistical parameter to characterize signals backscattered from both whole blood and RBC suspensions at different flow velocities (from 10 to 60 cm/s) and hematocrits (from 20% to 50%) under a steady laminar flow condition. The Nakagami parameter, scaling parameter, backscatter amplitude profile and flow velocity profile across a flow tube were acquired using a 10 MHz focused ultrasonic transducer. The backscattered signal peaked approximately at the centerline of the flow tube due to the effects of RBC aggregation, with the peak value increasing as the flow velocity of whole blood decreased. The Nakagami parameter increased from 0.45 to 0.78 as the flow velocity increased from 10 to 60 cm/s. The probability density function (PDF) of signals backscattered from flowing whole blood conformed with a pre-Rayleigh distribution. The Nakagami parameter was close to 1 for signals backscattered from RBC suspensions at all the flow velocities and hematocrits tested, for which the PDF was Rayleigh distributed. These differences in the statistical distributions of backscattered signals between whole blood and RBC suspensions suggest that variations in the size of dynamic scatterers in the flow affect the shape of the backscattered signal envelope, which should be considered in future statistical models used to characterize blood properties. PMID:17673357

  17. MGS TES Measurements of Dust and Ice Aerosol Behaviors

    NASA Astrophysics Data System (ADS)

    Clancy, R. T.; Wolff, M. J.; Christensen, P. R.

    2000-10-01

    The Thermal Emission Spectrometer (TES, Christensen et al., Science, v279, 1692-1697, 1998) on board the Mars Global Surveyor obtains simultaneous solar band and thermal IR spectral emission-phase-function (EPF) observations with global spatial coverage and continuous seasonal sampling. These measurements allow the first comprehensive study of the coupled visible scattering and thermal IR absorption properties of Mars atmospheric aerosols, a fundamental requirement towards defining opacities, particle sizes, and particle shapes for separable dust and water ice aerosol components. Furthermore, TES limb sounding at solar band and IR wavelengths may be analyzed in the context of these EPF column determinations to constrain the distinctive vertical profile behaviors of dust and ice clouds. We present initial radiative transfer analyses of TES visible and IR EPFs, which indicate surprisingly complex dust and ice aerosol behaviors over all latitudes and seasons. Distinctive backscattering peaks of variable intensity are observed for several types of water ice clouds, along with evidence for ice-coated dust aerosols. We will present a broad spatial and temporal sampling of solar band and spectral IR results for Mars atmospheric ice and dust aerosols observed over the 1998-2000 period. This research is supported by the MGS Participating Scientist and MED Science Data Analysis programs.

  18. Remote Sensing of Vertical Distributions of Smoke Aerosol Off the Coast of Africa

    NASA Technical Reports Server (NTRS)

    Kaufman, Y. J.; Haywood, J. M.; Hobbs, P. V.; Hart, W.; Schmid, B.

    2003-01-01

    In 2004 NASA plans to launch the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations- CALIPSO mission, with a two-wavelength lidar aboard. CALIPSO will fly in formation with the Moderate Resolution Imaging Spectro-Radiometer (MODIS) on the Aqua satellite. Here we present inversions of combined aircraft lidar and MODIS data to study the properties of smoke off the southwest coast of Southern Africa. The inversion derives profiles of the aerosol extinction due to fine and coarse particles. Comparisons with three sets of airborne in situ measurements show excellent agreement of the aerosol extinction profiles; however the inversion derives smaller spectral dependence of the extinction than the in situ measurements. The inversion is sensitive to the aerosol backscattering-to-extinction ratio (BER). Due to nonsphericity of the coarse aerosols, the range of BERs of the smoke aerosol is 0.014 to 0.021 sr(sup -l) for the fine and coarse particles at 0.53 and 1.06 pm wavelengths, which do not differ much from the value for dust (0.016 sr(sup -1)) at these wavelengths.

  19. Simulation of improved daytime capabilities to retrieve aerosol extinction coefficient using Rotational Raman lidars

    NASA Astrophysics Data System (ADS)

    Madonna, Fabio; Amodeo, Aldo

    2015-04-01

    So far, most of the multi-wavelength Raman lidar observations of aerosols are performed at night, because Raman signals are weak compared to daylight background. Different techniques have been developed to improve Raman lidar daytime capabilities in the past years. Indeed, the retrieval of aerosol extinction during daytime is feasible through the detection of backscattered radiation due to the pure Rotational Raman Spectrum (PRRS) of molecular nitrogen or oxygen, much brighter than the vibration-rotation spectrum. The existing techniques for the measure of PRRS are based on small-bandwidth emitter and receiver systems and on a small receiver field of view to suppress the daylight background. They have been successfully tested and implemented in a few systems which are already in operational use within EARLINET (European Aerosol research Lidar NETwork). In this work, several different configurations used as receiver for a lidar system detecting the PRRS in daytime conditions are compared by means of numerical simulations. The configurations are mainly differentiated by the design of the spectral selection unit implemented in the receiver of each lidar system, based on a narrow-bandwidth filters, broad-band filters, grating spectrometers, and hybrid solutions. The research of configurations able to be more easily implemented on a large number of lidar systems within ACTRIS are explored. To show the performances of the investigated lidar configurations, a blind test has been carried out to get the simulated performances in the retrieval of the aerosol extinction profile during night-time and daytime starting from a known scenario. The atmospheric scenario used as the reference profile is represented by one of the night-time measurements with MUSA (MUlti-wavelength system for Aerosol) lidar at CNR-IMAA Atmospheric Observatory - CIAO (15.72E, 40.60N , 760 m a.s.l., Potenza, Italy). Though all the configuration considered in the blind test proved to be solid to

  20. Towards depth profiling of organic aerosols in real time using aerosol flowing atmospheric-pressure afterglow mass spectrometry (AeroFAPA-MS)

    NASA Astrophysics Data System (ADS)

    Brüggemann, Martin; Hoffmann, Thorsten

    2014-05-01

    Organic aerosol accounts for a substantial fraction of tropospheric aerosol and has implications on the earth's climate and human health. However, the characterization of its chemical composition and transformations remain a major challenge and is still connected to large uncertainties (IPCC, 2013). Recent measurements revealed that organic aerosol particles may reside in an amorphous or semi-solid phase state which impedes the diffusion within the particles (Virtanen et al., 2010; Shiraiwa et al., 2011). This means that reaction products which are formed on the surface of a particle, e.g. by OH, NO3 or ozone chemistry, cannot diffuse into the particle's core and remain at the surface. Eventually, this leads to particles with a core/shell structure. In the particles' cores the initial compounds are preserved whereas the shells contain mainly the oxidation products. By analyzing the particles' cores and shells separately, thus, it is possible to obtain valuable information on the formation and evolution of the aerosols' particle and gas phase. Here we present the development of the aerosol flowing atmospheric-pressure afterglow (AeroFAPA) technique which allows the mass spectrometric analysis of organic aerosols in real time. The AeroFAPA is an ion source based on a helium glow discharge at atmospheric pressure. The plasma produces excited helium species and primary reagent ions which are transferred into the afterglow region where the ionization of the analytes takes place. Due to temperatures of only 80 ° C to 150 ° C and ambient pressure in the afterglow region, the ionization is very soft and almost no fragmentation of organic molecules is observed. Thus, the obtained mass spectra are easy to interpret and no extensive data analysis procedure is necessary. Additionally, first results of a combination of the AeroFAPA-MS with a scanning mobility particle sizer (SMPS) suggest that it is not only possible to analyze the entire particle phase but rather that a

  1. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2011-11-01

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

  3. Profiling of aerosol microphysical properties at several EARLINET/AERONET sites during the July 2012 ChArMEx/EMEP campaign

    NASA Astrophysics Data System (ADS)

    José Granados-Muñoz, María; Navas-Guzmán, Francisco; Guerrero-Rascado, Juan Luis; Bravo-Aranda, Juan Antonio; Binietoglou, Ioannis; Nepomuceno Pereira, Sergio; Basart, Sara; María Baldasano, José; Belegante, Livio; Chaikovsky, Anatoli; Comerón, Adolfo; D'Amico, Giuseppe; Dubovik, Oleg; Ilic, Luka; Kokkalis, Panos; Muñoz-Porcar, Constantino; Nickovic, Slobodan; Nicolae, Doina; José Olmo, Francisco; Papayannis, Alexander; Pappalardo, Gelsomina; Rodríguez, Alejandro; Schepanski, Kerstin; Sicard, Michaël; Vukovic, Ana; Wandinger, Ulla; Dulac, François; Alados-Arboledas, Lucas

    2016-06-01

    The simultaneous analysis of aerosol microphysical properties profiles at different European stations is made in the framework of the ChArMEx/EMEP 2012 field campaign (9-11 July 2012). During and in support of this campaign, five lidar ground-based stations (Athens, Barcelona, Bucharest, Évora, and Granada) performed 72 h of continuous lidar measurements and collocated and coincident sun-photometer measurements. Therefore it was possible to retrieve volume concentration profiles with the Lidar Radiometer Inversion Code (LIRIC). Results indicated the presence of a mineral dust plume affecting the western Mediterranean region (mainly the Granada station), whereas a different aerosol plume was observed over the Balkans area. LIRIC profiles showed a predominance of coarse spheroid particles above Granada, as expected for mineral dust, and an aerosol plume composed mainly of fine and coarse spherical particles above Athens and Bucharest. Due to the exceptional characteristics of the ChArMEx database, the analysis of the microphysical properties profiles' temporal evolution was also possible. An in-depth analysis was performed mainly at the Granada station because of the availability of continuous lidar measurements and frequent AERONET inversion retrievals. The analysis at Granada was of special interest since the station was affected by mineral dust during the complete analyzed period. LIRIC was found to be a very useful tool for performing continuous monitoring of mineral dust, allowing for the analysis of the dynamics of the dust event in the vertical and temporal coordinates. Results obtained here illustrate the importance of having collocated and simultaneous advanced lidar and sun-photometer measurements in order to characterize the aerosol microphysical properties in both the vertical and temporal coordinates at a regional scale. In addition, this study revealed that the use of the depolarization information as input in LIRIC in the stations of Bucharest,

  4. 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.

  5. Aerosol chemistry in Beijing, China: Different pollution regimes and diurnal profiles

    NASA Astrophysics Data System (ADS)

    van Pinxteren, D.; Brüggemann, E.; Gnauk, T.; Iinuma, Y.; Müller, K.; Nowak, A.; Achtert, P.; Wiedensohler, A.; Herrmann, H.

    2009-04-01

    The rapid economic development during the last three decades in China has led to a severe decrease in air quality, especially in densely populated regions such as Beijing, Shanghai, and the Pearl River Delta. Although during last years a number of measures for air pollution control have been implemented especially in the capital Beijing, air pollution is still regarded to be one of the top environmental concerns in China during the next decade. To better characterize the processes leading to the frequently observed high concentrations of air pollutants on a regional scale, the international field campaign "Campaigns of Air Quality Research in Beijing 2006" (CAREBEIJING2006) was conducted in summer 2006. Organized by the Peking University, project partners from Japan, Korea, Hong Kong, Germany, and China studied the various aspects of gaseous and particulate air pollution in a megacity environment. In this contribution, we present chemical data of size-resolved particles, obtained by a 5-stage Berner impactor (0.05-10 μm) during 3 weeks at both an urban and a suburban site in the area of Beijing, China. The sampling time of the impactors was about 4-5 hours. This allowed for taking four size-resolved samples per day and obtaining rough diurnal profiles of particle components. The samples were analyzed for inorganic ions (Cl-, SO42-, NO3-, NH4+, K+, Ca2+, Na+, Mg2+), carbon sum parameters (OC, EC, WSOC), and a variety of organic compounds such as dicarboxylic acids, alkanes, PAHs and, for the first time in China, nitrooxy-organosulfates. On average, the observed PM10 mass concentrations were 133 μg m-3 and 112 μg m-3 at the urban and suburban site, respectively. In general, the observed concentrations of particulate pollutants were similarly high as reported from previous studies in the Beijing summer atmosphere. A back trajectory analysis allowed the classification of the samples into different meteorological categories with different air mass origins. A high

  6. Spectra of Particulate Backscattering in Natural Waters

    NASA Technical Reports Server (NTRS)

    Gordon, Howard, R.; Lewis, Marlon R.; McLean, Scott D.; Twardowski, Michael S.; Freeman, Scott A.; Voss, Kenneth J.; Boynton, Chris G.

    2009-01-01

    Hyperspectral profiles of downwelling irradiance and upwelling radiance in natural waters (oligotrophic and mesotrophic) are combined with inverse radiative transfer to obtain high resolution spectra of the absorption coefficient (a) and the backscattering coefficient (bb) of the water and its constituents. The absorption coefficient at the mesotrophic station clearly shows spectral absorption features attributable to several phytoplankton pigments (Chlorophyll a, b, c, and Carotenoids). The backscattering shows only weak spectral features and can be well represented by a power-law variation with wavelength (lambda): b(sub b) approx. Lambda(sup -n), where n is a constant between 0.4 and 1.0. However, the weak spectral features in b(sub b), suggest that it is depressed in spectral regions of strong particle absorption. The applicability of the present inverse radiative transfer algorithm, which omits the influence of Raman scattering, is limited to lambda < 490 nm in oligotrophic waters and lambda < 575 nm in mesotrophic waters.

  7. 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

  8. Point and column aerosol radiative closure during ACE 1: Effects of particle shape and size

    NASA Astrophysics Data System (ADS)

    Fridlind, A. M.; Jacobson, M. Z.

    2003-02-01

    We used data collected during the First Aerosol Characterization Experiment (ACE 1) to study point and column aerosol radiative closure over the remote ocean. To test point closure, total and hemispheric backscattering coefficients calculated with a Mie single-scattering model were compared with measurements made by ship and aircraft at three wavelengths (400, 550, and 700 nm). On the ship, assuming spherical particles, calculated total scattering was usually within 10% of measurements (closure obtained in >80% of the cases) but calculated backscattering was usually 15-25% lower than measurements (closure obtained in <50% of the cases). When a model for particle nonsphericity was applied to the dried sea spray, assuming the particles to be ideal cubes or irregular convex and concave crystals resulted in overestimation of backscattering. However, when nonsphericity parameters were fit to the measurements, calculated backscattering was also usually within 10% of measurements (closure obtained in >80% of the cases). On the aircraft, however, calculated scattering and backscattering were usually lower than measurements by 20-45% regardless of assumed particle shape (closure obtained in <50% of the cases), likely owing to differences in the aerosol inlet penetration efficiencies to each instrument or unidentified uncertainties in the measured number size distributions or scattering coefficients. To test column closure, aerosol extinction profiles calculated from in situ observations (below 5.5 km) and satellite observations (above 5.5 km) were vertically integrated, and the resulting aerosol optical depth was compared with measurements made on the ship during two clear-sky days at three wavelengths (500, 778, and 862 nm). Calculated spectral optical depths were usually within 25% of measurements (closure obtained at one or more wavelengths on both days), and agreement at longer wavelengths was improved when satellite measurements were spectrally scaled using in situ

  9. 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

  10. Aerosol vertical distribution, optical properties and transport over Corsica (western Mediterranean)

    NASA Astrophysics Data System (ADS)

    Léon, J.-F.; Augustin, P.; Mallet, M.; Bourrianne, T.; Pont, V.; Dulac, F.; Fourmentin, M.; Lambert, D.; Sauvage, B.

    2015-03-01

    This paper presents the aerosol vertical distribution observed in the western Mediterranean between February and April 2011 and between February 2012 and August 2013. An elastic backscattering lidar was continuously operated at a coastal site in the northern part of Corsica Island (Cap Corse) for a total of more than 14 000 h of observations. The aerosol extinction coefficient retrieved from cloud-free lidar profiles are analyzed along with the SEVIRI satellite aerosol optical depth (AOD). The SEVIRI AOD was used to constrain the retrieval of the aerosol extinction profiles from the lidar range-corrected signal and to detect the presence of dust or pollution aerosols. The daily average AOD at 550 nm is 0.16 (±0.09) and ranges between 0.05 and 0.80. A seasonal cycle is observed with minima in winter and maxima in spring-summer. High AOD days (above 0.3 at 550 nm) represent less than 10% of the totality of daily observations and correspond to the large scale advection of desert dust from Northern Africa or pollution aerosols from Europe. The respective origin of the air masses is confirmed using FLEXPART simulations in the backward mode. Dust events are characterized by a large turbid layer between 2 and 5 km height while pollution events show a lower vertical development with a thick layer below 3 km in altitude. However low level dust transport is also reported during spring while aerosol pollution layer between 2 and 4 km height has been also observed. We report an effective lidar ratio at 355 nm for pollution aerosols 68 (±13) Sr while it is 63 (±18) Sr for dust. The daily mean AOD at 355 nm for dust events is 0.61 (±0.14) and 0.71 (±0.16) for pollution aerosols events.

  11. Gradient Correlation Method for the Stabilization of Inversion Results of Aerosol Microphysical Properties Retrieved from Profiles of Optical Data

    NASA Astrophysics Data System (ADS)

    Kolgotin, Alexei; Müller, Detlef; Romanov, Anton; Chemyakin, Eduard

    2016-06-01

    Correlation relationships between aerosol microphysical parameters and optical data are investigated. The results show that surface-area concentrations and extinction coefficients are linearly correlated with a correlation coefficient above 0.99 for arbitrary particle size distribution. The correlation relationships that we obtained can be used as constraints in our inversion of optical lidar data. Simulation studies demonstrate a significant stabilization of aerosol microphysical data products if we apply the gradient correlation method in our traditional regularization technique.

  12. Modeling LIDAR Detection of Biological Aerosols to Determine Optimum Implementation Strategy

    SciTech Connect

    Sheen, David M.; Aker, Pam M.

    2007-09-19

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

  13. Observing wind, aerosol particles, cloud and precipitation: Finland's new ground-based remote-sensing network

    NASA Astrophysics Data System (ADS)

    Hirsikko, A.; O'Connor, E. J.; Komppula, M.; Korhonen, K.; Pfüller, A.; Giannakaki, E.; Wood, C. R.; Bauer-Pfundstein, M.; Poikonen, A.; Karppinen, T.; Lonka, H.; Kurri, M.; Heinonen, J.; Moisseev, D.; Asmi, E.; Aaltonen, V.; Nordbo, A.; Rodriguez, E.; Lihavainen, H.; Laaksonen, A.; Lehtinen, K. E. J.; Laurila, T.; Petäjä, T.; Kulmala, M.; Viisanen, Y.

    2013-08-01

    The Finnish Meteorological Institute, in collaboration with the University of Helsinki, has established a new ground-based remote-sensing network in Finland. The network consists of five topographically, ecologically and climatically different sites distributed from southern to northern Finland. The main goal of the network is to monitor air pollution and boundary layer properties in near real time, with a Doppler lidar and ceilometer at each site. In addition to these operational tasks, two sites are members of the Aerosols, Clouds, and Trace gases Research InfraStructure Network (ACTRIS); a Ka-band Doppler cloud radar at Sodankylä will provide cloud retrievals within CloudNet, and a multi-wavelength Raman lidar, POLLYXT (POrtabLe Lidar sYstem eXTended), in Kuopio provides optical and microphysical aerosol properties through EARLINET (European Aerosol Research Lidar Network to Establish an Aerosol Climatology). Three C-band weather radars are located in the Helsinki metropolitan area and are deployed for operational and research applications. We carried out two inter-comparison campaigns to investigate the Doppler lidar performance. The aims of the campaigns were to compare the backscatter coefficient and retrieved wind profiles, and to optimise the lidar sensitivity through adjusting the telescope focus and data-integration time to ensure enough signals in low-aerosol-content environments. The wind profiles showed good agreement between different lidars. However, due to inaccurate telescope focus setting and varying receiver sensitivity, backscatter coefficient profiles showed disagreement between the lidars. Harsh Finnish winters could pose problems, but, due to the built-in heating systems, low ambient temperatures had no, or only a minor, impact on the lidar operation: including scanning-head motion. However, accumulation of snow and ice on the lens has been observed, which can lead to formation of a water/ice layer thus attenuating the signal inconsistently

  14. Observations of aerosol and clouds with the ABLE and MAL lidars during the mid-latitude and Arctic ENVISAT validation campaigns

    NASA Astrophysics Data System (ADS)

    Matthey, Renaud; Cacciani, Marco; Fiocco, Giorgio; Martinez, Ana Alfaro; Martucci, Giovanni; Mitev, Valentin; Pace, Giandomenico; Stefanutti, Leopoldo

    2003-08-01

    The airborne lidars ABLE and MALs (up and down) participated in 2002 and 2003 in several ENVISAT validation campaigns performed by the high-altitude research aircraft M-55 "Geophysica". From M-55 ABLE provides vertical profiles of the backscattering ratio at three wavelengths (1064, 532 and 355 nm) and of the aerosol depolarisation ratio at 532 nm. MAL-up and MAL-down are probing respectively upward and downward from M-55. They are single-wavelength (532 nm) elastic backscatter lidars providing backscatter and depolarisation ratios in a short range from the aircraft. The lidars provide the cloud top altitude and, for optically thin clouds, the optical and geometrical depths. During the validation flights, cloud and aerosol layers have been detected under night- and day-time conditions. Hereafter measurements acquired during those campaigns by the ABLE and MAL instruments are presented and compared. With respect to ENVISAT cloud and aerosol products validation, we discuss the possibility to use the combined cloud and aerosol database from the two types of lidars on board M-55.

  15. A Measurement-Based Climatology of Aerosol Radiative Properties and Direct Radiative Forcing in the Southeastern U.S.-Initial Results from a Regionally-Representative Site

    NASA Astrophysics Data System (ADS)

    Sherman, J. P.; Robertson, L.; Taubman, B.; Brewbaker, A.; Sheridan, P. J.

    2011-12-01

    order to assess the relative influences of source types and regions on DRF. Results from this study will also be presented. A time-of-flight aerosol mass spectrometer will soon be operational, leading to the apportionment of aerosol optical properties by chemical composition and expansion of currently-employed techniques to include estimates of the relative anthropogenic contribution to DRF. Vertical aerosol and cloud layer profiles measured by a recently-deployed micro-pulsed lidar and the hygroscopic dependence of aerosol total light scattering and hemispheric backscattering measured by a scanning humidograph will be incorporated into the radiative transfer model used to compute DRF, leading to improved accuracy and the capability to validate and constrain aerosol properties in regional CTMs and to validate satellite-based aerosol retrievals.

  16. Observing wind, aerosol particles, cloud and precipitation: Finland's new ground-based remote-sensing network

    NASA Astrophysics Data System (ADS)

    Hirsikko, A.; O'Connor, E. J.; Komppula, M.; Korhonen, K.; Pfüller, A.; Giannakaki, E.; Wood, C. R.; Bauer-Pfundstein, M.; Poikonen, A.; Karppinen, T.; Lonka, H.; Kurri, M.; Heinonen, J.; Moisseev, D.; Asmi, E.; Aaltonen, V.; Nordbo, A.; Rodriguez, E.; Lihavainen, H.; Laaksonen, A.; Lehtinen, K. E. J.; Laurila, T.; Petäjä, T.; Kulmala, M.; Viisanen, Y.

    2014-05-01

    The Finnish Meteorological Institute, in collaboration with the University of Helsinki, has established a new ground-based remote-sensing network in Finland. The network consists of five topographically, ecologically and climatically different sites distributed from southern to northern Finland. The main goal of the network is to monitor air pollution and boundary layer properties in near real time, with a Doppler lidar and ceilometer at each site. In addition to these operational tasks, two sites are members of the Aerosols, Clouds and Trace gases Research InfraStructure Network (ACTRIS); a Ka band cloud radar at Sodankylä will provide cloud retrievals within CloudNet, and a multi-wavelength Raman lidar, PollyXT (POrtabLe Lidar sYstem eXTended), in Kuopio provides optical and microphysical aerosol properties through EARLINET (the European Aerosol Research Lidar Network). Three C-band weather radars are located in the Helsinki metropolitan area and are deployed for operational and research applications. We performed two inter-comparison campaigns to investigate the Doppler lidar performance, compare the backscatter signal and wind profiles, and to optimize the lidar sensitivity through adjusting the telescope focus length and data-integration time to ensure sufficient signal-to-noise ratio (SNR) in low-aerosol-content environments. In terms of statistical characterization, the wind-profile comparison showed good agreement between different lidars. Initially, there was a discrepancy in the SNR and attenuated backscatter coefficient profiles which arose from an incorrectly reported telescope focus setting from one instrument, together with the need to calibrate. After diagnosing the true telescope focus length, calculating a new attenuated backscatter coefficient profile with the new telescope function and taking into account calibration, the resulting attenuated backscatter profiles all showed good agreement with each other. It was thought that harsh Finnish

  17. 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.

  18. Conditions for observation of the enhanced backscattering phenomenon in a turbulent atmosphere

    NASA Astrophysics Data System (ADS)

    Chrzanowski, Janusz; Kirkiewicz, Jozef; Kravtsov, Yuri A.

    2003-11-01

    Influence of enhanced backscattering effect on laser measurements of dust and aerosols content in a turbulent atmosphere is discussed. It is shown that doubling of the backscattered light intensity, characteristic for enhanced backscattering, leads to overestimating dust content in the air. To avoid undesirable effect of overestimation, it is recommended to displace receiving aperture sidewise relatively to laser source. Other method to eliminate overestimation is to use wider laser beam and extended receiving aperture as compared to coherence radius of the scattered wave field.

  19. A Framework for Aerosol-Cloud Interactions Monitoring

    NASA Astrophysics Data System (ADS)

    Russchenberg, H. W. J.; Sarna, K.

    2014-12-01

    A broad range of strategies have been used to study Aerosol-Cloud Interactions (ACI). However, the wide scope of methods and scales used makes it difficult to quantitatively compare result from different studies. In this paper, we propose a method of aerosol-cloud interaction monitoring based on widely available remote sensing instruments and easily applicable at many different observatories. This method provides a way of identifying cases where a change in the aerosol environment causes a change in the cloud. In this scheme we attempt to use (as far as possible) the observed signal from lidar and radar. For an aerosol proxy we use the attenuated backscatter (sensitive to aerosol concentration) and to obtain information about changes in the cloud we use the radar reflectivity factor (sensitive to cloud droplet size and concentration). Assuming a positive dependence between the number concentration of cloud droplets and the number concentration of aerosol we expect that an increase of the attenuated backscatter coefficient will correspond to a small increase of the radar reflectivity factor (due to the increase of cloud droplets concentration). However, the slope of this correlation will vary. A number of factors, such as meteorology or cloud drop microphysical properties, can influence changes in a cloud. For that reason we put a constraint on the liquid water content using liquid water path information from microwave radiometers. This limitation ensures that the variability in the cloud will be primarily due to changes in microphysical properties associated with the variation in aerosols. Further, we limit the cases only to non-precipitating, low-level stratiform and stratocumulus clouds without drizzle. Although this method is based on a synergy of instruments, we use widely available systems for an efficient evaluation of the aerosol influence on the cloud. The main advantages of this scheme are the use of direct observables from widely spread remote sensing

  20. 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.

  1. 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

  2. A New Approach to Inverting and De-Noising Backscatter from Lidar Observations

    NASA Astrophysics Data System (ADS)

    Marais, Willem; Hen Hu, Yu; Holz, Robert; Eloranta, Edwin

    2016-06-01

    Atmospheric lidar observations provide a unique capability to directly observe the vertical profile of cloud and aerosol scattering properties and have proven to be an important capability for the atmospheric science community. For this reason NASA and ESA have put a major emphasis on developing both space and ground based lidar instruments. Measurement noise (solar background and detector noise) has proven to be a significant limitation and is typically reduced by temporal and vertical averaging. This approach has significant limitations as it results in significant reduction in the spatial information and can introduce biases due to the non-linear relationship between the signal and the retrieved scattering properties. This paper investigates a new approach to de-noising and retrieving cloud and aerosol backscatter properties from lidar observations that leverages a technique developed for medical imaging to de-blur and de-noise images; the accuracy is defined as the error between the true and inverted photon rates. Hence non-linear bias errors can be mitigated and spatial information can be preserved.

  3. Temperatures and aerosol opacities of the Mars atmosphere at aphelion: Validation and inter-comparison of limb sounding profiles from MRO/MCS and MGS/TES

    NASA Astrophysics Data System (ADS)

    Shirley, James H.; McConnochie, Timothy H.; Kass, David M.; Kleinböhl, Armin; Schofield, John T.; Heavens, Nicholas G.; McCleese, Daniel J.; Benson, Jennifer; Hinson, David P.; Bandfield, Joshua L.

    2015-05-01

    We exploit the relative stability and repeatability of the Mars atmosphere at aphelion for an inter-comparison of Mars Global Surveyor/Thermal Emission Spectrometer (MGS/TES) and Mars Reconnaissance Orbiter/Mars Climate Sounder (MRO/MCS) nighttime temperature profiles and aerosol opacity profiles in Mars years 25, 26, 29, 30, and 31. Cross-calibration of these datasets is important, as they together provide an extended climatology for this planetary atmosphere. As a standard of comparison we employ temperature profiles obtained by radio occultation methods during the MGS mission in Mars years 24, 25, and 26. We first compare both zonal mean TES limb sounding profiles and zonal mean MCS limb sounding profiles with zonal means of radio occultation temperature profiles for the same season (Ls = 70-80°) and latitudes (55-70°N). We employ a statistical z test for quantifying the degree of agreement of temperature profiles by pressure level. For pressures less than 610 Pa (altitudes > 3 km), the ensemble mean temperature difference between the radio occultation and TES limb sounding profiles found in these comparisons was 1.7 ± 0.7 K. The ensemble mean temperature difference between radio occultation and MCS profiles was 1.4 ± 1.0 K. These differences fall within the formal error estimates for both TES and MCS, validating the accuracy of the instruments and their respective retrieval algorithms. In the second phase of our investigation, we compare aphelion season zonal mean TES limb sounding temperature, water ice opacity, and dust opacity profiles with those obtained at the same latitudes in different years by MCS. The ensemble mean temperature difference found for three comparisons between TES and MCS zonal mean temperature profiles was 2.8 ± 2.1 K. MCS and TES temperatures between 610 Pa and 5 Pa from 55 to 70°N are largely in agreement (with differences < 2 K) when water ice aerosol opacities are comparable. Temperature differences increase when the opacities

  4. Continental pollution in the western Mediterranean basin: vertical profiles of aerosol and trace gases measured over the sea during TRAQA 2012 and SAFMED 2013

    NASA Astrophysics Data System (ADS)

    Di Biagio, C.; Doppler, L.; Gaimoz, C.; Grand, N.; Ancellet, G.; Raut, J.-C.; Beekmann, M.; Borbon, A.; Sartelet, K.; Attié, J.-L.; Ravetta, F.; Formenti, P.

    2015-08-01

    In this study we present airborne observations of aerosol and trace gases obtained over the sea in the western Mediterranean basin during the TRAQA (TRansport and Air QuAlity) and SAFMED (Secondary Aerosol Formation in the MEDiterranean) campaigns in summer 2012 and 2013. A total of 23 vertical profiles were measured up to 5000 m above sea level over an extended area (40-45° N and 2° W-12° E) including the Gulf of Genoa, southern France, the Gulf of Lion, and the Spanish coast. During TRAQA and SAFMED the study area experienced a wide range of meteorological conditions which favoured pollution export from different sources located around the basin. Also, several events of dust outflows were measured during the campaigns. Observations from the present study show that continental pollution largely affects the western Mediterranean both close to coastal regions and in the open sea as far as ~ 250 km from the coastline. The measured aerosol scattering coefficient varies between ~ 20 and 120 Mm-1, while carbon monoxide (CO) and ozone (O3) mixing ratios are in the range of 60-165 and 30-85 ppbv, respectively. Pollution reaches 3000-4000 m in altitude and presents a very complex and highly stratified structure characterized by fresh and aged layers both in the boundary layer and in the free troposphere. Within pollution plumes the measured particle concentration in the Aitken (0.004-0.1 μm) and accumulation (0.1-1.0 μm) modes is between ~ 30 and 5000-6000 scm-3 (standard cm-3), which is comparable to the aerosol concentration measured in continental areas under pollution conditions. Additionally, our measurements indicate the presence of highly concentrated Aitken layers (10 000-15 000 scm-3) observed both close to the surface and in the free troposphere, possibly linked to the influence of new particle formation (NPF) episodes over the basin.

  5. Aerosol Layering Characterization Near the Gobi Desert by a Double Polarization Lidar System

    NASA Astrophysics Data System (ADS)

    Zhao, Y.; Boselli, A.; Sannino, A.; Song, C.; Spinelli, N.; Wang, X.

    2016-06-01

    In order to carry out 4-D (space and time) analysis of the atmospheric aerosol distribution and to make a characterization of their properties and time evolution, a transportable multi-wavelength, Elastic/Raman scanning lidar system with angular scanning capability has been realized. The system uses a diode pumped Nd:YAG laser source, specifically designed for this device, and a receiving systems able to detect elastic signals at 355, 532 and 1064 nm and Raman signals at 386, 407 and 607 nm. It also allows to perform aerosol depolarization measurements at both 355nm and 532nm. A first measurement campaign has been carried out in Dunhuang, North-West of China, in the region of the Gobi desert with the aims to study and characterize desert dust at source. Optical properties of aerosol layers developing in the atmosphere have been analyzed and lidar data are discussed in terms of profiles of aerosol backscatter coefficient at 355nm, 532nm, aerosol extinction coefficient at 355nm, aerosol depolarization ratio at 355nm and 532nm and water vapor mixing ratio. Depolarization ratio measured simultaneously at two wavelengths allowed also to study its dependence on the wavelength.

  6. Distribution of sulphuric acid aerosols in the clouds and upper haze of Venus using Venus Express VAST and VeRa temperature profiles

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

    Observations from Pioneer Venus and from SPICAV/SOIR aboard Venus Express (VEx) have shown the upper haze (UH) of Venus to be highly spatially and temporally variable, and populated by multiple particle size modes. Previous models of this system (e.g., Gao et al., 2014. Icarus 231, 83-98), using a typical temperature profile representative of the atmosphere (viz., equatorial VIRA profile), did not investigate the effect of temperature on the UH particle distributions. We show that the inclusion of latitude-dependent temperature profiles for both the morning and evening terminators of Venus helps to explain how the atmospheric aerosol distributions vary spatially. In this work we use temperature profiles obtained by two instruments onboard VEx, VeRa and SPICAV/SOIR, to represent the latitudinal temperature dependence. We find that there are no significant differences between results for the morning and evening terminators at any latitude and that the cloud base moves downwards as the latitude increases due to decreasing temperatures. The UH is not affected much by varying the temperature profiles; however, the haze does show some periodic differences, and is slightly thicker at the poles than at the equator. We also find that the sulphuric acid "rain" seen in previous models may be restricted to the equatorial regions of Venus, such that the particle size distribution is relatively stable at higher latitudes and at the poles.

  7. Extinction-to-backscatter ratios of Saharan dust layers derived from in situ measurements and CALIPSO overflights during NAMMA

    NASA Astrophysics Data System (ADS)

    Omar, Ali; Liu, Zhaoyan; Vaughan, Mark; Thornhill, Kenneth; Kittaka, Chieko; Ismail, Syed; Hu, Yongxiang; Chen, Gao; Powell, Kathleen; Winker, David; Trepte, Charles; Winstead, Edward; Anderson, Bruce

    2010-12-01

    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 August to September 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 two-color method to determine the corresponding 1064 nm Sa. This method yielded dust Sa ratios of 39.8 ± 1.4 and 51.8 ± 3.6 sr at 532 and 1064 nm, respectively. Second, 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 ± 3.5 and 50.0 ± 4 sr at 532 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 sea-salt 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 (± uncertainty) of 39.4 (±5.9) and 56.5 (±16.5) sr at 532 and 1064 nm, respectively, corresponding to percentage uncertainties of 15% and 29%. These results will provide a measurements-based estimate of the dust Sa for use in backscatter lidar inversion algorithms

  8. Optimal Estimation Retrievals of Aerosol Microphysical Properties from High Spectral Resolution Lidar (HSRL) and Polarimeter Data

    NASA Astrophysics Data System (ADS)

    Liu, X.; Ferrare, R. A.; Hostetler, C. A.; Burton, S. P.; Stamnes, S.; Mueller, D.; Chemyakin, E.; Sawamura, P.; Cairns, B.

    2015-12-01

    Knowledge of the vertical profile, composition, concentration, and size distribution of aerosols is required to quantify the impacts of aerosols on human health, global and regional climate, clouds and precipitation, and ocean ecosystems. We will describe an Optimal Estimation (OE) retrieval method that will use three wavelengths of aerosol backscattering (3β) and two wavelengths of aerosol extinction (2α). We will also describe how to use the OE framework to retrieve vertical profiles simultaneously using altitude resolved HSRL data. Finally, we will describe how to include additional measurements (e.g. polarimeter or Sun photometer) for improved aerosol microphysical property retrievals. In a traditional aerosol retrieval algorithm, one solves for aerosol size distributions under various parameter space (rmin, rmax, real and imaginary refractive index) using Tikhonov (or other) regularization and then selects physically and mathematically meaningful solutions from hundreds of thousand retrievals. In an attempt to speed up the retrieval and to provide retrieval error estimates, the OE method solves for all related aerosol microphysical parameters (e.g. number concentrations, particle size distribution, real and imaginary part of refractive indices) simultaneously in a maximum-likelihood sense by fitting the observed data. Other quantities such as effective particle radius, surface area concentration, volume concentration, and single scattering albedo are also derived from the retrieved size distribution and the number concentrations. We will show preliminary results using both simulated data and airborne measurements from HSRL-2. Coincident airborne in-situ and surface remote sensing datasets will be used to evaluate the performance of the new OE algorithm.

  9. The Effect of Rain on Nadir Ocean Backscatter in TOPEX Radar Altimeter Data

    NASA Technical Reports Server (NTRS)

    Durden, Stephen L.

    1996-01-01

    Rainfall profile from the 14 GHz TRMM Precipitation Radar will require correction for attenuation effects. An important technique for this is the surface reference technique, which estimates the path attenuation through rain by comparing the clear air ocean backscatter with ocean backscatter in rain.

  10. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

    Measurements of real-time high spatial and temporal resolution profiles of combined water vapor and aerosols in the boundary layer have been a long standing observational challenge to the meteorological, weather forecasting, and climate science communities. To overcome the high reoccurring costs associated with radiosondes as well as the lack of sufficient water vapor measurements over the continental united states, a compact and low cost eye-safe all semiconductor-based micro-pulse differential absorption lidar (DIAL) has been developed for water vapor and aerosol profiling in the lower troposphere. The laser transmitter utilizes two continuous wave external cavity diode lasers operating in the 830 nm absorption band as the online and offline seed laser sources. An optical switch is used to sequentially injection seed a tapered semiconductor optical amplifier (TSOA) with the two seed laser sources in a master oscillator power amplifier (MOPA) configuration. The TSOA is actively current pulsed to produce up to 7 μJ of output energy over a 1 μs pulse duration (150 m vertical resolution) at a 10 kHz pulse repetition frequency. The measured laser transmitter spectral linewidth is less than 500 kHz while the long term frequency stability of the stabilized on-line wavelength is ± 55 MHz. The laser transmitter spectral purity was measured to be greater than 0.9996, allowing for simultaneous measurements of water vapor in the lower and upper troposphere. The DIAL receiver utilizes a commercially available full sky-scanning capable 35 cm Schmidt-Cassegrain telescope to collect the scattered light from the laser transmitter. Light collected by the telescope is spectrally filtered to suppress background noise and is coupled into a fiber optic cable which acts as the system field stop and limits the full angle field of view to 140 μrad. The light is sampled by a fiber coupled APD operated in a Geiger mode. The DIAL instrument is operated autonomously where water vapor and

  12. 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

  13. Relationship between the fraction of backscattered light and the asymmetry parameter

    NASA Astrophysics Data System (ADS)

    Horvath, Helmuth

    2015-04-01

    The fraction of backscattered light is defined as the ratio of the integral of the volume scattering function over the backward half solid angle divided by the integral of the volume scattering function over the full solid angle. It can be measured with an integrating nephelometer. On the other hand the asymmetry parameter is the integral over the full solid angle of the volume scattering function weighted with the cosine of the scattering angle divided by the integral of the volume scattering function. To determine the asymmetry parameter the measurement of the angular dependence of the volume scattering function is needed, which can be obtained e.g. with a polar nephelometer. The asymmetry parameter is an important input parameter for radiative transfer calculations in order to obtain information of effects of the atmospheric aerosol effects (climate, screening, visibility, and others). Unfortunately measurements of the asymmetry parameter of the atmospheric aerosol are scarce. It is obvious, that a relation between the asymmetry parameter and the backscattered fraction should exist: the smaller the backscattered fraction, the more asymmetric the scattering, thus the larger the asymmetry parameter. A large set of 6500 angular scattering data have been obtained at various locations of the world: Vienna (Austria), Kyoto (Japan), Granada (Spain) and Palencia (Spain). The aerosols in these locations were considerably different, ranging from continental, urban, maritime, to desert dust. The volume scattering function has been measured between 5° and 175° , the values for 0° to 5° and 175° to 180° have been obtained by extrapolation of the shape of the curve, thus the whole range of scattering angles was available for calculating the backscattered fraction and the asymmetry parameter of the aerosol. PIC A summary of all data is shown in figure 1. The majority of the data points suggest an unanimous relation between backscattering and asymmetry parameter. The

  14. Thermoluminescent aerosol analysis

    NASA Technical Reports Server (NTRS)

    Rogowski, R. S.; Long, E. R., Jr. (Inventor)

    1977-01-01

    A method for detecting and measuring trace amounts of aerosols when reacted with ozone in a gaseous environment was examined. A sample aerosol was exposed to a fixed ozone concentration for a fixed period of time, and a fluorescer was added to the exposed sample. The sample was heated in a 30 C/minute linear temperature profile to 200 C. The trace peak was measured and recorded as a function of the test aerosol and the recorded thermoluminescence trace peak of the fluorescer is specific to the aerosol being tested.

  15. Radiative Effects of Aerosols

    NASA Technical Reports Server (NTRS)

    Valero, Francisco P. J.

    1997-01-01

    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 pollution haze layer 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.

  16. Lidar Observations of the Pinatubo Stratospheric Aerosol Cloud over Frascati, Italy

    NASA Technical Reports Server (NTRS)

    Congeduti, Fernando; Adriani, Alberto; Gobbi, Gian Paolo; Centurioni, Sante

    1992-01-01

    The Pinatubo eruption of June 1991 introduced large plumes into the local stratosphere. On several occasions, volcanic gases and particles reached altitudes of about 30 km, and spread towards the west. A lidar system has been operating to monitor the evolution of the stratospheric aerosol cloud. The backscattering ratio profiles of eight different measurements were chosen to summarize the most significant occurrences of the event. Since the beginning of the winter planetary wave activity, the Pinatubo cloud integrated backscatter exceeded El Chichon's. In this context, the perturbation generated by El Chichon can only be assumed as a lower limit of the one which will follow the Pinatubo eruption. Observations of the event are still in progress.

  17. Cloud and Aerosol Retrieval for the 2001 GLAS Satellite Lidar Mission

    NASA Technical Reports Server (NTRS)

    Hart, William D.; Palm, Stephen P.; Spinhirne, James D.

    2000-01-01

    The Geoscience Laser Altimeter System (GLAS) is scheduled for launch in July of 2001 aboard the Ice, Cloud and Land Elevation Satellite (ICESAT). In addition to being a precision altimeter for mapping the height of the Earth's icesheets, GLAS will be an atmospheric lidar, sensitive enough to detect gaseous, aerosol, and cloud backscatter signals, at horizontal and vertical resolutions of 175 and 75m, respectively. GLAS will be the first lidar to produce temporally continuous atmospheric backscatter profiles with nearly global coverage (94-degree orbital inclination). With a projected operational lifetime of five years, GLAS will collect approximately six billion lidar return profiles. The large volume of data dictates that operational analysis algorithms, which need to keep pace with the data yield of the instrument, must be efficient. So, we need to evaluate the ability of operational algorithms to detect atmospheric constituents that affect global climate. We have to quantify, in a statistical manner, the accuracy and precision of GLAS cloud and aerosol observations. Our poster presentation will show the results of modeling studies that are designed to reveal the effectiveness and sensitivity of GLAS in detecting various atmospheric cloud and aerosol features. The studies consist of analyzing simulated lidar returns. Simulation cases are constructed either from idealized renditions of atmospheric cloud and aerosol layers or from data obtained by the NASA ER-2 Cloud Lidar System (CLS). The fabricated renditions permit quantitative evaluations of operational algorithms to retrieve cloud and aerosol parameters. The use of observational data permits the evaluations of performance for actual atmospheric conditions. The intended outcome of the presentation is that climatology community will be able to use the results of these studies to evaluate and quantify the impact of GLAS data upon atmospheric modeling efforts.

  18. 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

  19. Analysis of the Impact of Major Dust Events on the Aerosols Characteristics over Saudi Arabia

    NASA Astrophysics Data System (ADS)

    Farahat, Ashraf; El-Askary, Hesham; Al-Shaibani, Abdulaziz; Hariri, Mustafa M.

    2015-04-01

    The Kingdom of Saudi Arabia is a major source of atmospheric dust. Frequent dust storms blow up and significantly affect human activities, airports and citizens' health. Aerosols optical and physical characteristics are influenced by major dust storms outbreaks. In this, paper, ground based AERONET measurements are integrated with space-borne sensors, namely MODIS and CALIPSO to analyze aerosols' characteristics during March - May of 2009 where a massive dust storm blew up and caused a widespread heavy atmospheric dust load over Saudi Arabia and the same period during 2010, where less dust activities were reported. The MODIS Deep Blue AOD analysis showed similar aerosols pattern over the land, however a substantial variance in aerosol loading during March - May 2009 compared with the same period in 2010 was observed. The angstrom exponent analysis showed that the majority of aerosol measurements in 2009 and 2010 are dominated by coarse-mode particles with angstrom exponent < 0.5. Detailed analysis of aerosol optical properties shows significant influence of coarse mode particles in the enhanced aerosol loading in 2009. The volume depolarization rations (VDR) derived from CALIPSO backscattering measurements is used to find latitudinal profile of mean aerosol optical depth to indicate the type of particles and to discriminate spherical aerosols with non-spherical particles. Acknowledgement The authors would like to acknowledge the support provided by the King Abdel Aziz City for Science & Technology (KACST) for funding this work under grant No. (MT-32-76). The support provided by the Deanship of Research at King Fahd University of Petroleum & Minerals (KFUPM) is gratefully acknowledged.

  20. Comparison of Aerosol Single Scattering Albedos Derived by Diverse Techniques In Two North Atlantic Experiments

    NASA Technical Reports Server (NTRS)

    Russell, P. B.; Redemann, J.; Schmid, B.; Bergstrom, R. W.; Livingston, J. M.; McIntosh, D. M.; Ramirez, S. A.; Hartley, S.; Hobbs, P. V.; Quinn, P. K.

    2002-01-01

    Aerosol single scattering albedo omega (the ratio of scattering to extinction) is important in determining aerosol climatic effects, in explaining relationships between calculated and measured radiative fluxes, and in retrieving aerosol optical depths from satellite radiances. Recently, two experiments in the North Atlantic region, the Tropospheric Aerosol Radiative Forcing Observational Experiment (TARFOX) and the Second Aerosol Characterization Experiment (ACE-2), determined aerosol omega by a variety of techniques. The techniques included fitting of calculated to measured radiative fluxes; retrievals of omega from skylight radiances; best fits of complex refractive index to profiles of backscatter extinction, and size distribution; and in situ measurements of scattering and absorption at the surface and aloft. Both TARFOX and ACE-2 found a fairly wide range of values for omega at midvisable wavelengths approx. 550 nm, with omega(sub midvis) greater than or equal to 0.85 and less than or equal to 0.99 for the marine aerosol impacted by continental pollution. Frequency distributions of omega could usually be approximated by lognormals in omega(sub max) - omega, with some occurrence of bimodality, suggesting the influence of different aerosol sources or processing. In both TARFOX and ACE-2, closure tests between measured and calculated radiative fluxes yielded best-fit values of omega(sub midvis) 0.90 +/- 0.04 for the polluted boundary layer. Although these results have the virtue of describing the column aerosol unperturbed by sampling, they are subject to questions about representativeness and other uncertainties (e.g., thermal offsets, unknown gas absorption) The other techniques gave larger values for omega(sub midvis) for the polluted boundary layer, with a typical result of omega(sub midvis) = 0.95 +/- 0.04. Current uncertainties in omega are large in terms of climate effects More tests are needed of the consistency among different methods and of

  1. Absolute calibration of the Jenoptik CHM15k-x ceilometer and its applicability for quantitative aerosol monitoring

    NASA Astrophysics Data System (ADS)

    Geiß, Alexander; Wiegner, Matthias

    2014-05-01

    The knowledge of the spatiotemporal distribution of atmospheric aerosols and its optical characterization is essential for the understanding of the radiation budget, air quality, and climate. For this purpose, lidar is an excellent system as it is an active remote sensing technique. As multi-wavelength research lidars with depolarization channels are quite complex and cost-expensive, increasing attention is paid to so-called ceilometers. They are simple one-wavelength backscatter lidars with low pulse energy for eye-safe operation. As maintenance costs are low and continuous and unattended measurements can be performed, they are suitable for long-term aerosol monitoring in a network. However, the signal-to-noise ratio is low, and the signals are not calibrated. The only optical property that can be derived from a ceilometer is the particle backscatter coefficient, but even this quantity requires a calibration of the signals. With four years of measurements from a Jenoptik ceilometer CHM15k-x, we developed two methods for an absolute calibration on this system. This advantage of our approach is that only a few days with favorable meteorological conditions are required where Rayleigh-calibration and comparison with our research lidar is possible to estimate the lidar constant. This method enables us to derive the particle backscatter coefficient at 1064 nm, and we retrieved for the first time profiles in near real-time within an accuracy of 10 %. If an appropriate lidar ratio is assumed the aerosol optical depth of e.g. the mixing layer can be determined with an accuracy depending on the accuracy of the lidar ratio estimate. Even for 'simple' applications, e.g. assessment of the mixing layer height, cloud detection, detection of elevated aerosol layers, the particle backscatter coefficient has significant advantages over the measured (uncalibrated) attenuated backscatter. The possibility of continuous operation under nearly any meteorological condition with temporal

  2. Continental pollution in the Western Mediterranean Basin: vertical profiles of aerosol and trace gases measured over the sea during TRAQA 2012 and SAFMED 2013

    NASA Astrophysics Data System (ADS)

    Di Biagio, C.; Doppler, L.; Gaimoz, C.; Grand, N.; Ancellet, G.; Raut, J.-C.; Beekmann, M.; Borbon, A.; Sartelet, K.; Attié, J.-L.; Ravetta, F.; Formenti, P.

    2015-03-01

    In this study we present airborne observations of aerosol and trace gases obtained over the sea in the Western Mediterranean Basin during the TRAQA (TRansport and Air QuAlity) and SAFMED (Secondary Aerosol Formation in the MEDiterranean) campaigns in summers 2012 and 2013. A total of 23 vertical profiles were measured up to 5000 m a.s.l. over an extended area (40-45° N latitude and 2° W-12° E longitude) including the Gulf of Genoa, Southern France, the Gulf of Lion, and the Spanish coast. TRAQA and SAFMED successfully measured a wide range of meteorological conditions which favoured the pollution export from different sources located around the basin. Also, several events of dust outflows were measured during the campaigns. Observations from the present study indicate that continental pollution largely affects the Western Mediterranean both close to coastal regions and in the open sea as far as ~250 km from the coastline. Aerosol layers not specifically linked with Saharan dust outflows are distributed ubiquitously which indicates quite elevated levels of background pollution throughout the Western Basin. The measured aerosol scattering coefficient varies between ~20 and 120 M m-1, while carbon monoxide (CO) and ozone (O3) mixing ratios are in the range of 60-170 and 30-85 ppbv, respectively. Pollution reaches 3000-4000 m in altitude and presents a very complex and highly stratified structure characterized by fresh and aged layers both in the boundary layer and in the free troposphere. Within pollution plumes the measured particle concentration in the Aitken (0.004-0.1 μm) and accumulation (0.1-1.0 μm) modes is between ˜ 100 and 5000-6000 s cm-3 (standard cm-3), which is comparable to the aerosol concentration measured in continental urban areas. Additionally, our measurements indicate the presence of highly concentrated Aitken layers (10 000-15 000 s cm-3) observed both close to the surface and in the free troposphere, possibly linked to the influence of new

  3. Remote sensing of tropospheric gases and aerosols with airborne DIAL system

    NASA Technical Reports Server (NTRS)

    Browell, E. V.

    1983-01-01

    The multipurpose airborne DIAL system developed at NASA Langley Research Center is characterized, and the published results of tropospheric O3, H2O, and aerosol-backscatter remote-sensing experiments performed in 1980 and 1981 are summarized. The system comprises two tunable dye lasers pumped by frequency-doubled Nd:YAG lasers, dielectric-coated steering optics, a 36-cm-diameter Cassegrain receiver telescope, gateable photomultiplier tubes, and a minicomputer data-processing unit for real-time calculation of gas concentrations and backscattering profiles. The transmitted energy of the 100-microsec-separated dye-laser pulses is 40, 80, or 50 mJ/pulse at around 300, 600, or 720-nm wavelength, respectively. Good agreement was found between DIAL-remote-sensed and in-situ H2O and O3 profiles of the lower troposphere and O3 profiles of the tropopause region, and the usefulness of DIAL backscattering measurements in the study of boundary-layer and tropospheric dynamics is demonstrated. The feasibility of DIAL sensing of power-plant or urban plume SO2, of urban-area (or rural-area column-content) NO2, and of temperature and H2O (simultaneously using a third laser) has been suggested by simulation studies.

  4. Moving Toward Continuous Satellite Monitoring of PM2.5 Using the GOES Aerosol/Smoke Product (GASP) and Aircraft Profiles

    NASA Astrophysics Data System (ADS)

    Stehr, J. W.; Kondragunta, S.; Anderson, D. C.; Arkinson, H.; Brent, L. C.; Goldberg, D.; He, H.; Liaskos, C.; Ring, A.; Dickerson, R. R.; Carpenter, S.; Ciren, P.; Xu, C.

    2012-12-01

    The NOAA Geostationary Operational Environmental Satellite (GOES) makes measurements of aerosol optical depth (AOD) every 30 minutes during daylight hours. Those measurements then feed the Automated Smoke Detection and Tracking algorithm that uses fire counts, trajectory modeling and pattern recognition to identify fire plumes, especially in the western U.S. Tying these satellite measurements to surface measurements of fine particles (PM2.5) would be a considerable benefit to the air quality community and to people who live in areas with elevated fine particle concentrations. Currently, these retrievals are useful in identifying areas of elevated PM2.5 concentrations and in forecasting PM2.5 by federal, state and local agencies, but are largely limited to qualitative measures of fine particle loading. Among other issues, layers of fine particles well above ground level, cloud contamination, and particle growth by addition of water in areas of high relative humidity are examples of barriers to a direct relationship between surface PM2.5 and satellite AOD. We have identified a path forward by using aircraft profiles to determine the vertical distribution of aerosol scattering in the atmosphere. In addition, long-term measurements of scattering and rapid measurements of PM2.5 at ground-based field sites have provided a relationship between scattering and mass. Simultaneous measurements of relative humidity and temperature allow one to calculate scattering the particles would have in a dry environment and relate that to fine particle mass measurements. A relationship between rapid scattering measurements and much slower PM2.5 mass measurements is then developed, which is used to tie rapid aircraft measurements of scattering to mass. In turn, aircraft profiles are then used to tie column measurements to those at the ground and to identify cases when satellite retrievals are likely to fail. The resulting algorithm should apply throughout much of the eastern U.S., so long

  5. 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

  6. Lidar observation of the 2011 Puyehue-Cordón Caulle volcanic aerosols at Lauder, New Zealand

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    On 4 June 2011, the Puyehue-Cordón Caulle volcanic complex (40.6° S, 72.1° W) in Chile erupted violently and injected volcanic aerosols into the atmosphere. For the safety of civil aviation, continuous lidar observations were made at Lauder, New Zealand (45.0° S, 169.7° E), from 11 June through 6 July 2011. To study the influence of the volcanic aerosols on Greenhouse gases Observing SATellite (GOSAT) products, we analyzed lidar data at a wavelength of 532 nm and derived the backscattering ratio and depolarization ratio profiles. During June and July, within the altitude range of 10-15 km, the volcanic aerosols had high depolarization ratios (20-35%), an indication of non-spherical volcanic ash particles. The time series of the backscattering ratio during continuous observations had three peaks occurring at about 12 day intervals: 26.7 at 11.2 km on 11 June, 18.1 at 12.0 km on 23 June, and 5.3 at 11.1 km on 6 July. The optical depth of the volcanic aerosols was 0.45 on 11 June, when the continuous lidar observation started, 0.31 on 23 June, and 0.12 on 6 July. The depolarization ratio values remained high up to a month after the eruption and the small wavelength exponent calculated from the backscattering coefficients at 532 nm and 1064 nm suggest that a major constituent of the volcanic aerosols was large, non-spherical particles. The presence of volcanic ash in the stratosphere might affect the error in GOSAT XCO2 retrieval using the 1.6 μm band.

  7. Lidar observation of the 2011 Puyehue-Cordón Caulle volcanic aerosols at Lauder, New Zealand

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

    On 4 June 2011, the Puyehue-Cordón Caulle volcanic complex (40.6° S, 72.1° W) in Chile erupted violently and injected volcanic aerosols into the atmosphere. For the safety of civil aviation, continuous lidar observations were made at Lauder, New Zealand (45.0° S, 169.7° E), from 11 June through 6 July 2011. The purpose of our study is to quantify the influence of the volcanic ejections from large eruptions, and we use the data from the ground-based lidar observation. We analyzed lidar data at a wavelength of 532 nm and derived the backscattering ratio and depolarization ratio profiles. During June and July, within the altitude range of 10-15 km, the volcanic aerosols had high depolarization ratios (20-35%), an indication of non-spherical volcanic ash particles. The time series of the backscattering ratio during continuous observations had three peaks occurring at about 12-day intervals: 26.7 at 11.2 km on 11 June, 18.1 at 12.0 km on 23 June, and 5.3 at 11.1 km on 6 July. The optical depth of the volcanic aerosols was 0.45 on 11 June, when the continuous lidar observation started, 0.31 on 23 June, and 0.12 on 6 July. The depolarization ratio values remained high up to a month after the eruption, and the small wavelength exponent calculated from the backscattering coefficients at 532 nm and 1064 nm suggests that a major constituent of the volcanic aerosols was large, non-spherical particles. The presence of volcanic ash in the stratosphere might affect the error in Greenhouse gases Observing SATellite (GOSAT) XCO2 retrieval using the 1.6 μm band. We briefly discuss the influence of the increased aerosols on GOSAT products.

  8. 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.

  9. The detection and interpretation of long-term atmospheric change: Tasks in association with the shuttle solar backscatter ultraviolet spectral radiometer

    NASA Technical Reports Server (NTRS)

    Frederick, John E.

    1987-01-01

    The objectives are to develop techniques to detect and remove long-term instrument drifts from the operational Solar Backscatter Ultraviolet (SBUV/2) data base using periodic measurements made by the Shuttle Solar Backscatter Ultraviolet Spectral Radiometer and to evaluate the potential effects of scattering by atmospheric aerosols on our ability to detect trends in ozone using SBUV-class instruments.

  10. Aerosol and cloud typing with an automated 24/7 aerosol lidar

    NASA Astrophysics Data System (ADS)

    Baars, Holger; Seifert, Patric; Wandinger, Ulla

    2015-04-01

    Modern sophisticated multi-wavelength Raman polarization lidars have the ability to measure autonomous and unattended in 24/7 mode. These aerosol lidars can deliver backscatter, extinction, and depolarization profiles of the atmosphere which can be used for a target categorization, i.e. the determination of different aerosol and cloud types. However, to derive the optical particle properties a calibration of the lidar signals in the free atmosphere, where only Rayleigh scattering occurs, is needed. This calibration is usually done manually case by case and thus prohibits automatic data analysis and particle typing. To overcome this limitation, the mobile EARLINET lidar PollyXT of TROPOS was deployed continuously without changes in the instrumental setup during two field campaigns in the framework of the German HD(CP)2 project to obtain temporally stable lidar signals. The temporal stability together with the high performance and good characterization of the lidar lead to the possibility of an absolute lidar calibration. The corresponding calibration constant was derived in two ways: first by using manually Raman and Klett retrievals for selected periods and second by using the aerosol optical depth (AOD) from co-located AERONET sun photometer measurements. The derived calibration constants show a high temporal stability and a good agreement between both methods and thus allowed the continuous calibration of the lidar and the retrieval of the attenuated backscatter coefficient at three wavelengths. In addition, the calibrated volume depolarization ratio, obtained following EARLINET recommendations, is continuously available. After correction for the molecular contribution, these four quantities were used for an aerosol and cloud typing in terms of particle size and shape. The final categorization leads to 11 categories, e.g. clean atmosphere, small spherical particles, large non-spherical particles, water droplets, ice crystals and corresponding mixtures. In this

  11. Aerosol cloud interaction: a multiplatform-scenario-based methodology

    NASA Astrophysics Data System (ADS)

    Landulfo, Eduardo; Lopes, Fabío. J. S.; Guerrero-Rascado, Juan Luis; Alados-Arboledas, Lucas

    2015-10-01

    Suspended atmospheric particles i.e. aerosol particles go through many chemical and physical processes and those interactions and transformations may cause particle change in size, structure and composition regulated by mechanisms, which are also present in clouds. These interactions play a great role in the radiation transfer in the atmosphere and are not completely understood as competing effects might occur which are known as indirect aerosol effects. Performing measurements and experiments in remote sensing to improve the knowledge of these processes are also a challenge. In face of that we propose a multi-platform approach based lidar, sun photometry and satellite observations which should be characterized under a scenario perspective in which given the cloud height, geometric and optical geometries in a diurnal/nocturnal basis will make possible to apply different analytical tools in each a set of product that specify the aerosol present in the vicinity of clouds, their optical and physical properties. These scenarios are meant to aid in tagging the expected products and help in creating a robust database to systematically study the aerosol-cloud interaction.In total we will present 6 scenarios: 3 under daylight conditions, 3 under at nighttime. Each scenario and their counterpart should be able to provide the cloud base/top height, aerosol backscattering profile and cloud optical/geometric thickness. In each instance we should count on a 5 wavelength Raman lidar system measurement, a collocated sun photometer and CALIPSO/MODIS observation from AQUA/TERRA platforms. To further improve the aerosol cloud interaction the Raman lidar system should have a water vapor channel or moreover a liquid water channel. In our study we will present a two-day case study to show the methodology feasibility and its potential application.

  12. 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

  13. Flux maximization techniques for compton backscatter depth profilometry.

    PubMed

    Lawson, L

    1993-01-01

    Resolution in x-ray backscatter imaging has often been hampered by low fluxes. But, for a given set of resolution requirements and geometric constraints, it is possible to define a maximization problem in the geometric parameters for which the solution is the maximum flux possible in those circumstances. In this way, resolution in noncritical directions can be traded for improved resolution in a desired direction. Making this the thickness, or surface normal direction, makes practicable the depth profiling of layered structures. Such techniques were applied to the problem of imaging the layered structure of corroding aircraft sheet metal joints using Compton backscatter. PMID:21307450

  14. Atmospheric Temperature Profile Measurements Using Mobile High Spectral Resolution Lidar

    NASA Astrophysics Data System (ADS)

    Razenkov, Ilya I.; Eloranta, Edwin W.

    2016-06-01

    The High Spectral Resolution Lidar (HSRL) designed at the University of Wisconsin-Madison discriminates between Mie and Rayleigh backscattering [1]. It exploits the Doppler effect caused by thermal motion of molecules, which broadens the spectrum of the transmitted laser light. That allows for absolute calibration of the lidar and measurements of the aerosol volume backscatter coefficient. Two iodine absorption filters with different absorption line widths (a regular iodine vapor filter and Argon buffered iodine filter) allow for atmospheric temperature profile measurements. The sensitivity of the measured signal-to-air temperature ratio is around 0.14%/K. The instrument uses a shared telescope transmitter-receiver design and operates in eyesafe mode (the product of laser average power and telescope aperture equals 0.1 Wm2 at 532 nm).

  15. Optical fiber characterization: Backscatter, time domain bandwidth, refracted from near field and interlaboratory comparisons, volume 1

    NASA Astrophysics Data System (ADS)

    Danielson, B. L.; Day, G. W.; Franzen, D. L.; Kim, E. M.; Young, M.

    1982-09-01

    Optical fiber waveguide measurements are described. Systems to determine the backscatter, bandwidth, and index profile are covered in detail. Measurement comparisons between laboratories are given for fiber attenuation, bandwidth, numerical aperture, and core diameter.

  16. Ultrasonic backscatter from cancellous bone: the apparent backscatter transfer function.

    PubMed

    Hoffmeister, Brent K; Mcpherson, Joseph A; Smathers, Morgan R; Spinolo, P Luke; Sellers, Mark E

    2015-12-01

    Ultrasonic backscatter techniques are being developed to detect changes in cancellous bone caused by osteoporosis. Many techniques are based on measurements of the apparent backscatter transfer function (ABTF), which represents the backscattered power from bone corrected for the frequency response of the measurement system. The ABTF is determined from a portion of the backscatter signal selected by an analysis gate of width τw delayed by an amount τd from the start of the signal. The goal of this study was to characterize the ABTF for a wide range of gate delays (1 μs ≤ τd ≤ 6 μs) and gate widths (1 μs ≤ τw ≤ 6 μs). Measurements were performed on 29 specimens of human cancellous bone in the frequency range 1.5 to 6.0 MHz using a broadband 5-MHz transducer. The ABTF was found to be an approximately linear function of frequency for most choices of τd and τw. Changes in τd and τw caused the frequency-averaged ABTF [quantified by apparent integrated backscatter (AIB)] and the frequency dependence of the ABTF [quantified by frequency slope of apparent backscatter (FSAB)] to change by as much as 24.6 dB and 6.7 dB/MHz, respectively. τd strongly influenced the measured values of AIB and FSAB and the correlation of AIB with bone density (-0.95 ≤ R ≤ +0.68). The correlation of FSAB with bone density was influenced less strongly by τd (-0.97 ≤ R ≤ -0.87). τw had a weaker influence than τd on the measured values of AIB and FSAB and the correlation of these parameters with bone density. PMID:26683412

  17. Extended validation of the GOSAT-observed CO2 and CH4 at TCCON sites with co-located aerosol profiling

    NASA Astrophysics Data System (ADS)

    Morino, I.; Uchino, O.; Yoshida, Y.; Kikuchi, N.; Inoue, M.; Nakamae, K.; Yokota, T.; Sherlock, V.; Liley, B.; Kawakami, S.; Ohyama, H.; Nagai, T.; Sakai, T.; Uchiyama, A.; Yamazaki, A.; Arai, K.; Okumura, H.

    2012-12-01

    Version 01.xx retrievals of the column-averaged dry-air mole fraction of carbon dioxide (XCO2) and methane (XCH4) from the Greenhouse gases Observing SATellite (GOSAT) short wave infrared spectra (released in August 2010) were validated using data from the Total Carbon Column Observing Network (TCCON). The standard deviation of the differences between the GOSAT ver. 01.xx retrievals and TCCON XCO2 and XCH4 was about 1% (1-σ), and the GOSAT retrievals were biased low by 8.85 ppm and 20.4 ppb for XCO2 and XCH4 respectively. We therefore investigated the influence of aerosols and thin cirrus clouds on XCO2 by lidar and sky radiometer at Tsukuba TCCON site (36.051N, 140.122E), and found that it was important to take into account vertical profiles of aerosols and thin cirrus clouds and to use more adequate solar irradiance database in order to improve the GOSAT XCO2 data. Based on these results, we applied a new retrieval algorithm to the new GOSAT L1B spectral data (ver. 141.141) provided by the Japan Aerospace Exploration Agency (JAXA). The uncertainties of the new GOSAT SWIR XCO2 and XCH4 data (ver. 02.00) are greatly decreased compared with those of version 01.xx. To further improve the GOSAT data quality, we have started to investigate the impact of aerosols and thin cirrus clouds on the GOSAT data (ver. 02.xx) over Tsukuba and Saga (33.241N, 130.288E) in Japan and Lauder (45.038S, 169.684E) in New Zealand using co-located FTS, lidar and sky radiometer measurements.

  18. BACKSCAT lidar backscatter simulation: User's guide for version 2.0

    NASA Astrophysics Data System (ADS)

    Hummel, J. R.; Longtin, D. R.; Paul, N. L.; Jones, J. R.

    1991-07-01

    BACKSCAT is a computer simulation of atmospheric backscatter from a laser radar (lidar) system. The computer code can simulate operating conditions for a variety of viewing, laser system, and atmospheric conditions. BACKSCAT Version 2.0 has been totally redesigned. The redesign effort has included the addition of several new features as well as improvements to the code. As with Version 1.0, BACKSCAT Version 2.0 is modular in design. This allows for further expansion and growth in the code. Wind dependent desert aerosols and cirrus clouds have been added. Both are based on formulation used in LOWTRAN 7. The cirrus cloud models include standard cirrus clouds as well as subvisual clouds. An all new User Interface System has also been developed. The new interface is designed to be easy to use while providing the operator with maximum flexibility. The interface system includes a built-in graphics package that permits the user to display the results from a simulation. The interface system also permits the user to include molecular scattering profiles based on a library of built-in model atmospheres or a user-supplied radiosonde profile.

  19. A Raman Lidar as Operational Tool for Long-Term Water Vapor, Temperature and Aerosol Profiling in the Swiss Meteorological Office

    NASA Astrophysics Data System (ADS)

    Simeonov, Dr; Dinoev, Dr; Serikov, Dr; Calpini, Dr; Bobrovnikov, Dr; Arshinov, Dr; Ristori, Dr; van den Bergh, Dr; Parlange, Dr

    2010-09-01

    To satisfy the rising demands on the quality and frequency of atmospheric water vapor, temperature and aerosol measurements used for numerical weather prediction models, climate change observations and special events (volcanoes, dust and smoke transport) monitoring, MeteoSwiss decided to implement a lidar at his main aerological station in Payerne. The instrument is narrow field of view, narrowband UV Raman lidar designed for continuous day and night operational profiling of tropospheric water vapor, aerosol and temperature The lidar was developed and built by the Swiss Federal Institute of Technology- Lausanne (EPFL) within a joint project with MeteoSwiss. To satisfy the requirements for operational exploitation in a meteorological network the lidar had to satisfy a number of criteria, the most important of which are: accuracy and precision, traceability of the measurement, long-term data consistency, long-term system stability, automated operation, requiring minimal maintenance by a technician, and eye safety. All this requirements were taken into account during the design phase of the lidar. After a ten months test phase of the lidar at Payerne it has been in regular operation since August 2008. Selected data illustrating interesting atmospheric phenomena captured by the lidar as well as long-term intercomparison with collocated microwave radiometer, GPS, radiosonding and an airborne DIAL will be presented and discussed. The talk will address also the technical availability, alignment and calibration stabilities of the instrument.

  20. Aerosol model development for environmental monitoring in the coastal atmosphere surface layer

    NASA Astrophysics Data System (ADS)

    Kaloshin, Gennady A.; Matvienko, Gennady G.

    2007-06-01

    Extinction of radiation in the marine boundary layer is dominated by scattering and absorption due to atmospheric aerosol. It is known, that the extinction of optical radiation visible and near IR spectra in the marine surface layer is determined mainly by scattering and absorption atmospheric aerosol. It influences on a dependence of spectral transmission and extinction both natural, and artificial light that is of interest for a wide range of problems, in particular for radiating problems at studying laws of climate formation, and for lines of the applications connected to the forecast of a signal power in coastal conditions at an estimation of EO systems characteristics. This is important to optical retrievals from satellite, remote sensing at environmental monitoring, backscatter of light to space (including climate forcing), cloud properties etc. In unpolluted regions the greatest effects on near shore scattering extinction will be a result of sea-salt from breaking waves and variations in relative humidity. The role of breaking waves appears to be modulated by wind, tide, swell, wave spectra and coastal conditions. These influences will be superimposed upon aerosol generated by open ocean sea-salt aerosol that varies with wind speed. The focus of our study is the extinction and optical effects due to aerosol in a specific coastal region. This involves linking coastal physical properties to oceanic and meteorological parameters in order to develop predictive algorithms that describe 3-D aerosol structure and variability. The aerosol microphysical model of the marine and coastal atmosphere surface layer is considered. The model distinctive feature is parameterization of amplitude and width of the modes as functions of fetch and wind speed. In the paper the dN/dr behavior depending at change meteorological parameters, heights above sea level, fetch, wind speed and RH is show. On the basis of the developed model with usage of Mie theory for spheres the

  1. 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.

  2. Criteria of backscattering in chiral one-way photonic crystals

    NASA Astrophysics Data System (ADS)

    Cheng, Pi-Ju; Chang, Shu-Wei

    2016-03-01

    Optical isolators are important devices in photonic circuits. To reduce the unwanted reflection in a robust manner, several setups have been realized using nonreciprocal schemes. In this study, we show that the propagating modes in a strongly-guided chiral photonic crystal (no breaking of the reciprocity) are not backscattering-immune even though they are indeed insensitive to many types of scatters. Without the protection from the nonreciprocity, the backscattering occurs under certain circumstances. We present a perturbative method to calculate the backscattering of chiral photonic crystals in the presence of chiral/achiral scatters. The model is, essentially, a simplified analogy to the first-order Born approximation. Under reasonable assumptions based on the behaviors of chiral photonic modes, we obtained the expression of reflection coefficients which provides criteria for the prominent backscattering in such chiral structures. Numerical examinations using the finite-element method were also performed and the results agree well with the theoretical prediction. From both our theory and numerical calculations, we find that the amount of backscattering critically depends on the symmetry of scatter cross sections. Strong reflection takes place when the azimuthal Fourier components of scatter cross sections have an order l of 2. Chiral scatters without these Fourier components would not efficiently reflect the chiral photonic modes. In addition, for these chiral propagating modes, disturbances at the most significant parts of field profiles do not necessarily result in the most effective backscattering. The observation also reveals what types of scatters or defects should be avoided in one-way applications of chiral structures in order to minimize the backscattering.

  3. 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

  4. Study of aerosol microphysical properties profiles retrieved from ground-based remote sensing and aircraft in-situ measurements during a Saharan dust event

    NASA Astrophysics Data System (ADS)

    Granados-Muñoz, M. J.; Bravo-Aranda, J. A.; Baumgardner, D.; Guerrero-Rascado, J. L.; Pérez-Ramírez, D.; Navas-Guzmán, F.; Veselovskii, I.; Lyamani, H.; Valenzuela, A.; Olmo, F. J.; Titos, G.; Andrey, J.; Chaikovsky, A.; Dubovik, O.; Gil-Ojeda, M.; Alados-Arboledas, L.