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Sample records for aerosol intensive observation

  1. Aerosol classification using EARLINET measurements for an intensive observational period

    NASA Astrophysics Data System (ADS)

    Papagiannopoulos, Nikolaos; Mona, Lucia; Pappalardo, Gelsomina

    2016-04-01

    ACTRIS (Aerosols, Clouds and Trace gases Research Infrastructure Network) organized an intensive observation period during summer 2012. This campaign aimed at the provision of advanced observations of physical and chemical aerosol properties, at the delivery of information about the 3D distribution of European atmospheric aerosols, and at the monitoring of Saharan dust intrusions events. EARLINET (European Aerosol Research Lidar Network) participated in the ACTRIS campaign through the addition of measurements according to the EARLINET schedule as well as daily lidar-profiling measurements around sunset by 11 selected lidar stations for the period from 8 June - 17 July. EARLINET observations during this almost two-month period are used to characterize the optical properties and vertical distribution of long-range transported aerosol over the broader area of Mediterranean basin. The lidar measurements of aerosol intensive parameters (lidar ratio, depolarization, Angstrom exponents) are shown to vary with location and aerosol type. A methodology based on EARLINET observations of frequently observed aerosol types is used to classify aerosols into seven separate types. The summertime Mediterranean basin is prone to African dust aerosols. Two major dust events were studied. The first episode occurred from the 18 to 21 of the June and the second one lasted from 28 June to 6 July. The lidar ratio within the dust layer was found to be wavelength independent with mean values of 58±14 sr at 355 nm and 57±11 sr at 532 nm. For the particle linear depolarization ratio, mean values of 0.27±0.04 at 532 nm have been found. Acknowledgements. The financial support for EARLINET in the ACTRIS Research Infrastructure Project by the European Union's Horizon 2020 research and innovation programme under grant agreement no. 654169 and previously under grant agreement no. 262254 in the Seventh Framework Programme (FP7/2007-2013) is gratefully acknowledged.

  2. Characterization of intense aerosol episodes in the Mediterranean basin from satellite observations

    NASA Astrophysics Data System (ADS)

    Gkikas, Antonis; Hatzianastassiou, Nikos; Mihalopoulos, Nikolaos

    2014-05-01

    The properties and distribution of aerosols over the broader Mediterranean region are complex since particles of different nature are either produced within its boundaries or transported from other regions. Thus, coarse dust aerosols are transported primarily from Sahara and secondarily from Middle East, while fine polluted aerosols are either produced locally from anthropogenic activities or they are transported from neighbouring or remote European areas. Also during summer biomass aerosols are transported towards the Mediterranean, originating from massive and extended fires occurring in northern Balkans and Eastern Europe and favoured by the prevailing synoptic conditions. In addition, sea-salt aerosols originate from the Mediterranean Sea or the Atlantic Ocean. Occasionally, aerosols are encountered at very high concentrations (aerosol episodes or events) significantly affecting atmospheric dynamics and climate as well as human health. Given the coexistence of different aerosols as internal and external mixtures characterizing and discriminating between the different types of aerosol episodes is a big challenge. A characterization and classification of intense aerosol episodes in the Mediterranean basin (March 2000 - February 2007) is attempted in the present study. This is achieved by implementing an objective and dynamic algorithm which uses daily aerosol optical properties derived from satellite measurements, namely MODIS-Terra, Earth Probe (EP)-TOMS and OMI-Aura. The aerosol episodes are first classified into strong and extreme ones, according to their intensity, by means of aerosol optical depth at 550nm (AOD550nm). Subsequently, they are discriminated into the following aerosol types: (i) biomass/urban-industrial (BU), (ii) desert dust (DD), (iii) sea-salt like (SS), (iv) mixed (MX) and (v) undetermined (UN). The classification is based on aerosol optical properties accounting for the particles' size (Ångström exponent, Effective radius), the

  3. Retrieval of Intensive Aerosol Properties from MFRSR observations: Partly Cloudy Cases

    SciTech Connect

    Kassianov, Evgueni I.; Barnard, James C.; Berg, Larry K.; Flynn, Connor J.; Long, Charles N.

    2010-09-30

    An approach for the obtaining column intensive aerosol properties, namely the single scattering albedo (SSA) and asymmetry parameter (ASP), from the Multi-Filter Rotating Shadowband Radiometer (MFRSR) spectral observations under partly cloudy conditions is described. The approach involves the MFRSR-based aerosol retrieval for clear-sky periods and an interpolation of the retrieved column aerosol properties for cloudy periods. The observed weak diurnal variability of SSA and ASP at the surface and the close association of the surface intensive aerosol properties with their column counterparts form the basis of such interpolation. The approach is evaluated by calculating the corresponding clear-sky total, direct and diffuse fluxes at five wavelengths (415, 500, 615, 673 and 870 nm) and compare them with the observed fluxes. The aerosol properties provided by this approach are applied for (i) an examination of the statistical relationship between spectral (visible spectral range) and broadband values of the total normalized cloud radiative forcing and (ii) an estimation of the fractional sky cover. Data collected during 13 days with single-layer cumulus clouds observed at U.S. Department of Energy Atmospheric Radiation Measurement (ARM) Climate Research Facility (ACRF) Southern Great Plains (SGP) site during summer 2007 are applied to illustrate the performance and application of this approach.

  4. Retrieval of intensive aerosol properties from MFRSR observations: partly cloudy cases

    NASA Astrophysics Data System (ADS)

    Kassianov, Evgueni; Barnard, James; Berg, Larry K.; Flynn, Connor; Long, Charles

    2010-10-01

    An approach for the obtaining column intensive aerosol properties, namely the single scattering albedo (SSA) and asymmetry parameter (ASP), from the Multi-Filter Rotating Shadowband Radiometer (MFRSR) spectral observations under partly cloudy conditions is described. The approach involves the MFRSR-based aerosol retrieval for clear-sky periods and an interpolation of the retrieved column aerosol properties for cloudy periods. The observed weak diurnal variability of SSA and ASP at the surface and the close association of the surface intensive aerosol properties with their column counterparts form the basis of such interpolation. The approach is evaluated by calculating the corresponding clear-sky total, direct and diffuse fluxes at five wavelengths (415, 500, 615, 673 and 870 nm) and compare them with the observed fluxes. The aerosol properties provided by this approach are applied for (i) an examination of the statistical relationship between spectral (visible range) and broadband values of the total normalized cloud radiative forcing and (ii) an estimation of the fractional sky cover. Data collected during 13 days with single-layer cumulus clouds observed at U.S. Department of Energy Atmospheric Radiation Measurement (ARM) Climate Research Facility (ACRF) Southern Great Plains (SGP) site during summer 2007 are applied to illustrate the performance and application of this approach.

  5. "Radiative Closure Studies for Clear Skies During the ARM 2003 Aerosol Intensive Observation Period"

    SciTech Connect

    J. J. Michalsky, G. P. Anderson, J. Barnard, J. Delamere, C. Gueymard, S. Kato, P. Kiedron, A. McComiskey, and P. Ricchiazzi

    2006-04-01

    The Department of Energy's Atmospheric Radiation Measurement (ARM) program sponsored a large intensive observation period (IOP) to study aerosol during the month of May 2003 around the Southern Great Plains (SGP) Climate Research Facility (CRF) in north central Oklahoma. Redundant measurements of aerosol optical properties were made using different techniques at the surface as well as in vertical profile with sensors aboard two aircraft. One of the principal motivations for this experiment was to resolve the disagreement between models and measurements of diffuse horizontal broadband shortwave irradiance at the surface, especially for modest aerosol loading. This paper focuses on using the redundant aerosol and radiation measurements during this IOP to compare direct beam and diffuse horizontal broadband shortwave irradiance measurements and models at the surface for a wide range of aerosol cases that occurred during 30 clear-sky periods on 13 days of May 2003. Models and measurements are compared over a large range of solar-zenith angles. Six different models are used to assess the relative agreement among them and the measurements. Better agreement than previously achieved appears to be the result of better specification of input parameters and better measurements of irradiances than in prior studies. Biases between modeled and measured direct irradiances are less than 1%, and biases between modeled and measured diffuse irradiances are less than 2%.

  6. Observations of Sub-3 nm Particles and Sulfuric acid Concentrations during Aerosol Life Cycle Intensive Observation Period 2011 in Long Island, New York

    NASA Astrophysics Data System (ADS)

    Yu, H.; Kanawade, V. P.; You, Y.; Hallar, A. G.; Mccubbin, I. B.; Chirokova, G.; Sedlacek, A. J.; Springston, S. R.; Wang, J.; Kuang, C.; Lee, Y.; McGraw, R. L.; Mikkila, J.; Lee, S.

    2012-12-01

    Atmospheric new particle formation (NPF) is an important source of aerosol particles. But the NPF processes are not well understood, in part because of our limited understanding of the formation of atmospheric sub-3 nm size aerosols and the limited number of simultaneous observations of particle size distributions and the aerosol nucleation precursors. During Aerosol Life Cycle Intensive Observation Period (July-August 2011) in Long Island, New York, we deployed a particle size magnifier (Airmodus A09) running at different working fluid saturation ratios and a TSI CPC3776 to extract the information of sub-3 nm particles formation. A scanning mobility particle spectrometer (SMPS), a chemical ionization mass spectrometer (CIMS), and a number of atmospheric trace gas analyzers were used to simultaneously measure aerosol size distributions, sulfuric acid, and other possible aerosol precursors, respectively. Our observation results show that sub-3 nm particles existed during both NPF and non-NPF events, indicating the formation of sub-3nm particle didn't always lead to NPF characterized by typical banana shaped aerosol size distributions measured by SMPS. However, sub-3 nm particles were much higher during NPF events. Sub-3 nm particles were well-correlated with sulfuric acid showing the same diurnal variations and noontime peaks, especially for NPF days. These results are consistent with laboratory studies showing that formation of sub-3 nm particles is very sensitive to sulfuric acid (than amines and ammonia) [Yu et al. GRL 2012]. HYSPLIT back trajectory analysis indicates that air masses from Great Lakes, containing more SO2, VOCs and secondary organics, may contribute to growth of sub-3 nm particles and NPF.

  7. Global Aerosol Observations

    Atmospheric Science Data Center

    2013-04-19

    ... atmosphere, directly influencing global climate and human health. Ground-based networks that accurately measure column aerosol amount and ... being used to improve Air Quality Models and for regional health studies. To assess the human-health impact of chronic aerosol exposure, ...

  8. Aerosol Observing System (AOS) Handbook

    SciTech Connect

    Jefferson, A

    2011-01-17

    The Aerosol Observing System (AOS) is a suite of in situ surface measurements of aerosol optical and cloud-forming properties. The instruments measure aerosol properties that influence the earth’s radiative balance. The primary optical measurements are those of the aerosol scattering and absorption coefficients as a function of particle size and radiation wavelength and cloud condensation nuclei (CCN) measurements as a function of percent supersaturation. Additional measurements include those of the particle number concentration and scattering hygroscopic growth. Aerosol optical measurements are useful for calculating parameters used in radiative forcing calculations such as the aerosol single-scattering albedo, asymmetry parameter, mass scattering efficiency, and hygroscopic growth. CCN measurements are important in cloud microphysical models to predict droplet formation.

  9. CALIPSO Observations of Aerosol Properties Near Clouds

    NASA Technical Reports Server (NTRS)

    Marshak, Alexander; Varnai, Tamas; Yang, Weidong

    2010-01-01

    Clouds are surrounded by a transition zone of rapidly changing aerosol properties. Characterizing this zone is important for better understanding aerosol-cloud interactions and aerosol radiative effects as well as for improving satellite measurements of aerosol properties. We present a statistical analysis of a global dataset of CALIPSO (Cloud-Aerosol Lidar and infrared Pathfinder Satellite Observation) Lidar observations over oceans. The results show that the transition zone extends as far as 15 km away from clouds and it is ubiquitous over all oceans. The use of only high confidence level cloud-aerosol discrimination (CAD) data confirms the findings. However, the results underline the need for caution to avoid biases in studies of satellite aerosol products, aerosol-cloud interactions, and aerosol direct radiative effects.

  10. Stratospheric aerosols - Observation and theory

    NASA Technical Reports Server (NTRS)

    Turco, R. P.; Whitten, R. C.; Toon, O. B.

    1982-01-01

    Important chemical and physical roles of aerosols are discussed, and properties of stratospheric aerosols as revealed by experimental data are described. In situ measurements obtained by mechanical collection and scattered-light detection yield the overall size distribution of the aerosols, and analyses of preserved aerosol precursor gases by wet chemical, cryogenic and spectroscopic techniques indicate the photochemical sources of particle mass. Aerosol chemical reactions including those of gaseous precursors, those in aqueous solution, and those on particle surfaces are discussed, in addition to aerosol microphysical processes such as nucleation, condensation/evaporation, coagulation and sedimentation. Models of aerosols incorporating such chemical and physical processes are presented, and simulations are shown to agree with measurements. Estimates are presented for the potential aerosol changes due to emission of particles and gases by aerospace operations and industrial consumption of fossil fuels, and it is demonstrated that although the climatic effects of existing levels of stratospheric aerosol pollution are negligible, potential increases in those levels might pose a future threat.

  11. Aerosol property retrieval from geostationary observations

    NASA Astrophysics Data System (ADS)

    Govaerts, Yves

    The Meteosat satellites play an important role for the generation of consistent long time series of aerosol properties. This importance relies on (i) the long duration of past (Meteosat First Generation, MFG) starting in 1982, present (Meteosat Second Generation, MSG) and future (Meteosat Third Generation, MTG) missions and (ii) their frequent cycle of acquisition that can be used to document the anisotropy of the surface and therefore the lower boundary condition for aerosol retrieval over land surfaces. Hence, a similar approach is used for the processing of each Meteosat generation based on a joint retrieval of surface reflectance and aerosol properties using an Optimal Estimation approach. Daily accumulation of the frequent Meteosat observations is used to discriminate the radiative effects that result from the surface anisotropy, from those caused by the aerosol scattering. The inverted forward model explicitly accounts for the surface anisotropy and the multiple scattering for the coupled surface-atmosphere system. Pinty et al. (2000) pioneered with the development of an original method to characterise simultaneously surface anisotropy and atmospheric scattering properties for the processing of MFG. Although these observations are limited to one single large VIS band poorly characterised, the main advantage of MFG relies in the duration of the archive (1982 - 2006), knowing that prior to 2000 space observations were very scarce. Despite these radiometric limitations, it is possible to detect major aerosol events like dust storms, fire plumes or pollution events, even over land surfaces. SEVIRI, on-board MSG, offers additional capabilities with its three solar channels and 15 min repeat cycle. AOD retrieval is much more accurate than with MFG and it is possible to discriminate among various aerosol classes. The additional FCI solar channels on-board MTG will offer improved capabilities with respect to MSG/SEVIRI for the retrieval of aerosol concentration and

  12. Raman lidar measurements of water vapor and aerosols during the atmospheric radiation measurement (ARM) remote clouds sensing (RCS) intensive observation period (IOP)

    SciTech Connect

    Melfi, S.H.; Starr, D.O`C.; Whiteman, D.

    1996-04-01

    The first Atmospheric Radiation Measurement (ARM) remote Cloud Study (RCS) Intensive Operations Period (IOP) was held during April 1994 at the Southern Great Plains (SGP) site. This experiment was conducted to evaluate and calibrate state-of-the-art, ground based remote sensing instruments and to use the data acquired by these instruments to validate retrieval algorithms developed under the ARM program.

  13. Space-borne Observations of Aerosols

    NASA Astrophysics Data System (ADS)

    Kaufman, Y. J.; Tanre, D.; Coakley, J. A.; Fraser, R. S.

    2005-12-01

    As early as 1963, photographs of the twilight horizon from the Vostok-6 spaceship were used by G. V. Rozenberg and V. V. Nikolaeva-Tereshkova to derive profiles of stratospheric aerosols. The launch of the ATS III satellite in 1967 sparked interest in using satellites to observe aerosol emission, transport, and their effects on climate, precipitation and health. The first use of autonomous satellites in aerosol research appears to be by Toby Carlson and Joe Prospero who tracked dust from the Sahara to the Americas in the early `70s using ATS III images. The launch of the calibrated Landsat instrument in 1972 allowed Bob Fraser to perform quantitative analyses of dust column concentrations for individual scenes. GOES launched in 1975 provided hourly data that allowed Walter Lyons and J.C. Dooley in the late 70's to report on the transport of sulfate air pollution which was later followed by estimates of the export of sulfate aerosol from the US to the Atlantic Ocean. With the launch of SAGE in 1979, Pat McCormick and co-workers began long term observations of statospheric aerosols. The launch of TIROS(N) and the AVHRR in 1979 marked the start of concerted efforts by Larry Stowe and his colleagues to produce operationally an aerosol product over oceans from the NOAA polar orbiting satellite. With the launch of the Earth Radiation Budget Experiment scanners in the late 1980's, Sundar Christopher and his colleagues began linking AVHRR-derived aerosol burdens to their effects on the Earth's radiation budget. A remarkable aspect of this early work is that instruments like the AVHRR, Landsat, and GOES imager were not originally designed to perform quantitative estimates of aerosol properties. In fact, corrections for the effects of aerosols in determining ocean reflectances implemented primarily through the work of Howard Gordon, facilitated much improved pictures of chlorophyll in the upper oceans than had been hoped for from CZCS data collected in the late 70's. This

  14. Observed high aerosol loading during dust events in Delhi

    NASA Astrophysics Data System (ADS)

    Singh, Khem; Aggarwal, Shankar G.; Jha, Arvind K.; Singh, Nahar; Soni, Daya; Gupta, Prabhat K.

    2012-07-01

    The present study reports aerosol mass loadings and their chemical property during integrated campaign for aerosol and radiation budget (ICARB) in the month of March to May 2006, at NPL, New Delhi. The Thar Desert in Rajasthan is located on the western end of India and south-west of Delhi is hot and arid region with intense aeolian activity and transport of aerosol by the prevailing southwest-west summer wind. Several dust episodes were observed in Delhi during summer 2006. The dust storm peaked on 29th April, 1 ^{st} and 8 ^{th} May 2006, with very high suspended particulate matter (SPM) concentrations 1986μg/m ^{3}, 1735μg/m ^{3} and 1511μg/m ^{3}, respectively. The average concentration of SPM in the month of March, April and May 2006 was 338 μg/m ^{3}, 698 μg/m ^{3} and 732 μg/m ^{3}, respectively. The SPM filter samples were analysed for water-soluble major cations (Na ^{+}, Ca ^{2+}, K ^{+}, and Mg ^{2+}) by atomic absorption spectrophotometry (AAS). Na ^{+} and Ca ^{2+} contribute about 54% and 20%, respectively of the total identified cation mass, indicating that they were most abundant cations. Strong correlations between Na ^{+}, Ca ^{2+}, K ^{+}, and Mg ^{2+} suggest their soil and dust origin. Such a high particle concentration observed during dust events may also be useful for study the effect of these aerosols on communication medium.

  15. Observational insights into aerosol formation from isoprene.

    PubMed

    Worton, David R; Surratt, Jason D; Lafranchi, Brian W; Chan, Arthur W H; Zhao, Yunliang; Weber, Robin J; Park, Jeong-Hoo; Gilman, Jessica B; de Gouw, Joost; Park, Changhyoun; Schade, Gunnar; Beaver, Melinda; Clair, Jason M St; Crounse, John; Wennberg, Paul; Wolfe, Glenn M; Harrold, Sara; Thornton, Joel A; Farmer, Delphine K; Docherty, Kenneth S; Cubison, Michael J; Jimenez, Jose-Luis; Frossard, Amanda A; Russell, Lynn M; Kristensen, Kasper; Glasius, Marianne; Mao, Jingqiu; Ren, Xinrong; Brune, William; Browne, Eleanor C; Pusede, Sally E; Cohen, Ronald C; Seinfeld, John H; Goldstein, Allen H

    2013-10-15

    Atmospheric photooxidation of isoprene is an important source of secondary organic aerosol (SOA) and there is increasing evidence that anthropogenic oxidant emissions can enhance this SOA formation. In this work, we use ambient observations of organosulfates formed from isoprene epoxydiols (IEPOX) and methacrylic acid epoxide (MAE) and a broad suite of chemical measurements to investigate the relative importance of nitrogen oxide (NO/NO2) and hydroperoxyl (HO2) SOA formation pathways from isoprene at a forested site in California. In contrast to IEPOX, the calculated production rate of MAE was observed to be independent of temperature. This is the result of the very fast thermolysis of MPAN at high temperatures that affects the distribution of the MPAN reservoir (MPAN / MPA radical) reducing the fraction that can react with OH to form MAE and subsequently SOA (F(MAE formation)). The strong temperature dependence of F(MAE formation) helps to explain our observations of similar concentrations of IEPOX-derived organosulfates (IEPOX-OS; ~1 ng m(-3)) and MAE-derived organosulfates (MAE-OS; ~1 ng m(-3)) under cooler conditions (lower isoprene concentrations) and much higher IEPOX-OS (~20 ng m(-3)) relative to MAE-OS (<0.0005 ng m(-3)) at higher temperatures (higher isoprene concentrations). A kinetic model of IEPOX and MAE loss showed that MAE forms 10-100 times more ring-opening products than IEPOX and that both are strongly dependent on aerosol water content when aerosol pH is constant. However, the higher fraction of MAE ring opening products does not compensate for the lower MAE production under warmer conditions (higher isoprene concentrations) resulting in lower formation of MAE-derived products relative to IEPOX at the surface. In regions of high NOx, high isoprene emissions and strong vertical mixing the slower MPAN thermolysis rate aloft could increase the fraction of MPAN that forms MAE resulting in a vertically varying isoprene SOA source. PMID:24004194

  16. MCS precipitation and downburst intensity response to increased aerosol concentrations

    NASA Astrophysics Data System (ADS)

    Clavner, M.; Cotton, W. R.; van den Heever, S. C.

    2015-12-01

    Mesoscale convective systems (MCSs) are important contributors to rainfall in the High Plains of the United States as well as producers of severe weather such as hail, tornados and straight-line wind events known as derechos. Past studies have shown that changes in aerosol concentrations serving as cloud condensation nuclei (CCN) alter the MCS hydrometeor characteristics which in turn modify precipitation yield, downdraft velocity, cold-pool strength, storm propagation and the potential for severe weather to occur. In this study, the sensitivity of MCS precipitation characteristics and convective downburst velocities associated with a derecho to changes in CCN concentrations were examined by simulating a case study using the Regional Atmospheric Modeling System (RAMS). The case study of the 8 May 2009 "Super-Derecho" MCS was chosen since it produced a swath of widespread wind damage in association with an embedded large-scale bow echo, over a broad region from the High Plains of western Kansas to the foothills of the Appalachians. The sensitivity of the storm to changes in CCN concentrations was examined by conducting a set of three simulations which differed in the initial aerosol concentration based on output from the 3D chemical transport model, GEOS-Chem. Results from this study indicate that while increasing CCN concentrations led to an increase in precipitation rates, the changes to the derecho strength were not linear. A moderate increase in aerosol concentration reduced the derecho strength, while the simulation with the highest aerosol concentrations increased the derecho intensity. These changes are attributed to the impact of enhanced CCN concentration on the production of convective downbursts. An analysis of aerosol loading impacts on these MCS features will be presented.

  17. Aerosol Microtops II sunphotometer observations over Ukraine

    NASA Astrophysics Data System (ADS)

    Bovchaliuk, V.; Bovchaliuk, A.; Milinevsky, G.; Danylevsky, V.; Sosonkin, M.; Goloub, Ph.

    2013-08-01

    Atmospheric aerosols and their impact on climate study are based on measurements by networks of ground-based instruments, satellite sensors, and measurements on portable sunphotometers. This paper presents the preliminary aerosol characteristics obtained during 2009-2012 using portable multi-wavelength Microtops II sunphotometer. Measurements were collected at different Ukraine sites in Kyiv, Odesa, Lugansk, Rivne, Chornobyl regions. The main aerosol characteristics, namely aerosol optical thickness (AOT) and Angstroem exponent, have been retrieved and analyzed. Aerosol data processing, filtering and calibration techniques are discussed in the paper.

  18. CALIPSO Observations of Volcanic Aerosol in the Stratosphere

    NASA Technical Reports Server (NTRS)

    Thomason, Larry W.; Pitts, Michael C.

    2008-01-01

    In the stratosphere, the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) has observed the presence of aerosol plumes associated with the eruptions several volcanoes including Montserrat (May 2006), Chaiten (May 2008), and Kasatochi (August 2008). While the dense ash plumes from these eruptions dissipate relatively quickly, CALIPSO continued to detect an enhanced aerosol layer from the Montserrat eruption from the initial observations in June 2006 well into 2008. Solar occultation missions were uniquely capable of monitoring stratospheric aerosol. However, since the end of long-lived instruments like the Stratospheric Aerosol and Gas Experiment (SAGE II), there has been no clear space-based successor instrument. A number of active instruments, some employing new techniques, are being evaluated as candidate sources of stratospheric aerosol data. Herein, we examine suitability of the CALIPSO 532-nm aerosol backscatter coefficient measurements.

  19. 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.

  20. Aerosol Remote Sensing from OMI Observations: An Overview

    NASA Technical Reports Server (NTRS)

    Torres, Omar; Ahn, Changwoo; Jethva, Hiren T.

    2014-01-01

    The unique advantage of OMI observations for the characterization of aerosol properties is the availability of radiance measurement at near UV wavelengths. In spite of its coarse spatial resolution, OMI's near UV observations make possible the characterization of aerosol absorption properties. This capability is unavailable in any of the currently operational high spatial resolution aerosol sensors. A unique decadal record of aerosol absorption optical depth and single scattering albedo from near UV observations has been produced from OMI observations. In this presentation we will review the evolution of OMI's aerosol retrieval capability over the past ten years including retrieval algorithm improvements, assessment of retrieved products, and development of new retrieval capabilities to infer the optical depth of aerosol layers located above clouds.

  1. Stratospheric Aerosol--Observations, Processes, and Impact on Climate

    NASA Technical Reports Server (NTRS)

    Kresmer, Stefanie; Thomason, Larry W.; von Hobe, Marc; Hermann, Markus; Deshler, Terry; Timmreck, Claudia; Toohey, Matthew; Stenke, Andrea; Schwarz, Joshua P.; Weigel, Ralf; Fueglistaler, Stephan; Prata, Fred J.; Vernier, Jean-Paul; Schlager, Hans; Barnes, John E.; Antuna-Marrero, Juan-Carlos; Fairlie, Duncan; Palm, Mathias; Mahieu, Emmanuel; Notholt, Justus; Rex, Markus; Bingen, Christine; Vanhellemont, Filip; Bourassa, Adam; Plane, John M. C.; Klocke, Daniel; Carn, Simon A.; Clarisse, Lieven; Trickl, Thomas; Neeley, Ryan; James, Alexander D.; Rieger, Landon; Wilson, James C.; Meland, Brian

    2016-01-01

    Interest in stratospheric aerosol and its role in climate have increased over the last decade due to the observed increase in stratospheric aerosol since 2000 and the potential for changes in the sulfur cycle induced by climate change. This review provides an overview about the advances in stratospheric aerosol research since the last comprehensive assessment of stratospheric aerosol was published in 2006. A crucial development since 2006 is the substantial improvement in the agreement between in situ and space-based inferences of stratospheric aerosol properties during volcanically quiescent periods. Furthermore, new measurement systems and techniques, both in situ and space based, have been developed for measuring physical aerosol properties with greater accuracy and for characterizing aerosol composition. However, these changes induce challenges to constructing a long-term stratospheric aerosol climatology. Currently, changes in stratospheric aerosol levels less than 20% cannot be confidently quantified. The volcanic signals tend to mask any nonvolcanically driven change, making them difficult to understand. While the role of carbonyl sulfide as a substantial and relatively constant source of stratospheric sulfur has been confirmed by new observations and model simulations, large uncertainties remain with respect to the contribution from anthropogenic sulfur dioxide emissions. New evidence has been provided that stratospheric aerosol can also contain small amounts of nonsulfatematter such as black carbon and organics. Chemistry-climate models have substantially increased in quantity and sophistication. In many models the implementation of stratospheric aerosol processes is coupled to radiation and/or stratospheric chemistry modules to account for relevant feedback processes.

  2. Observationally-constrained estimates of aerosol optical depths (AODs) over East Asia via data assimilation techniques

    NASA Astrophysics Data System (ADS)

    Lee, K.; Lee, S.; Song, C. H.

    2015-12-01

    Not only aerosol's direct effect on climate by scattering and absorbing the incident solar radiation, but also they indirectly perturbs the radiation budget by influencing microphysics and dynamics of clouds. Aerosols also have a significant adverse impact on human health. With an importance of aerosols in climate, considerable research efforts have been made to quantify the amount of aerosols in the form of the aerosol optical depth (AOD). AOD is provided with ground-based aerosol networks such as the Aerosol Robotic NETwork (AERONET), and is derived from satellite measurements. However, these observational datasets have a limited areal and temporal coverage. To compensate for the data gaps, there have been several studies to provide AOD without data gaps by assimilating observational data and model outputs. In this study, AODs over East Asia simulated with the Community Multi-scale Air Quality (CMAQ) model and derived from the Geostationary Ocean Color Imager (GOCI) observation are interpolated via different data assimilation (DA) techniques such as Cressman's method, Optimal Interpolation (OI), and Kriging for the period of the Distributed Regional Aerosol Gridded Observation Networks (DRAGON) Campaign (March - May 2012). Here, the interpolated results using the three DA techniques are validated intensively by comparing with AERONET AODs to examine the optimal DA method providing the most reliable AODs over East Asia.

  3. Aerosol properties from 4STAR observations: A sensitivity study

    NASA Astrophysics Data System (ADS)

    Kassianov, E.; Flynn, C.; Redemann, J.; Livingston, J. M.; Schmid, B.; Russell, P. B.; Sinyuk, A.

    2011-12-01

    Multi-spectral direct-beam observations of atmospheric aerosol and gas constituents have been taken successfully at a number of sites around the world by the airborne 14-Channel NASA Ames Airborne Tracking Sunphotometer (AATS-14). The recently developed airborne Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research (4STAR) is the next generation of AATS-14 with ultraviolet, visible and near-infrared spectral coverage, increased number of channels (more than 1500 pixels) and the sky-scanning ability of the ground-based AERONET sun/sky photometers. While it is generally agreed that more measurements in terms of independent wavelengths and scattering angles would offer enhanced aerosol retrievals, the potential afforded by improved observational capabilities of the 4STAR has not yet been fully characterized. This paper will attempt to place the importance of improved spectrally- and angularly-resolved 4STAR observations within the context of the well-known AERONET intensive-property retrieval. In particular, we have developed model data sets comparable to the 4STAR measurements of direct sun and sky radiances and evaluated the impact on the retrieval from subsampling in wavelength and scattering angle.

  4. Global CALIPSO Observations of Aerosol Changes Near Clouds

    NASA Technical Reports Server (NTRS)

    Varnai, Tamas; Marshak, Alexander

    2011-01-01

    Several recent studies have found that clouds are surrounded by a transition zone of rapidly changing aerosol optical properties and particle size. Characterizing this transition zone is important for better understanding aerosol-cloud interactions and aerosol radiative effects, and also for improving satellite retrievals of aerosol properties. This letter presents a statistical analysis of a monthlong global data set of Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) lidar observations over oceans. The results show that the transition zone is ubiquitous over all oceans and extends up to 15 km away from clouds. They also show that near-cloud enhancements in backscatter and particle size are strongest at low altitudes, slightly below the top of the nearest clouds. Also, the enhancements are similar near illuminated and shadowy cloud sides, which confirms that the asymmetry of Moderate Resolution Imaging Spectroradiometer reflectances found in an earlier study comes from 3-D radiative processes and not from differences in aerosol properties. Finally, the effects of CALIPSO aerosol detection and cloud identification uncertainties are discussed. The findings underline the importance of accounting for the transition zone to avoid potential biases in studies of satellite aerosol products, aerosol-cloud interactions, and aerosol direct radiative effects.

  5. Using OMI Observations to Measure Aerosol Absorption of Biomass Burning Aerosols Above Clouds

    NASA Technical Reports Server (NTRS)

    Torres, Omar; Bhartia, P. K.; Jethva, Hiren

    2011-01-01

    The presence of absorbing aerosol layers above clouds is unambiguously detected by the TOMS/OMI UV Aerosol Index (AI) that uses satellite observations at two near-UV channels. A sensitivity study using radiative transfer calculations shows that the AI signal of resulting from the presence of aerosols above clouds is mainly driven by the aerosol absorption optical depth and the optical depth of the underlying cloud. Based on these results, an inversion algorithm has been developed to retrieve the aerosol optical depth (AOD) of aerosol layers above clouds. In this presentation we will discuss the sensitivity analysis, describe the retrieval approach, and present results of applications of the retrieval method to OMI observations over the South Atlantic Ocean. Preliminary error analyses, to be discussed, indicate that the AOD can be underestimated (up to -30%) or overestimated (up to 60%) depending on algorithmic assumptions.

  6. Evaluation of Aerosol-Cloud Interactions in GISS ModelE Using ASR Observations

    NASA Astrophysics Data System (ADS)

    de Boer, G.; Menon, S.; Bauer, S. E.; Toto, T.; Bennartz, R.; Cribb, M.

    2011-12-01

    The impacts of aerosol particles on clouds continue to rank among the largest uncertainties in global climate simulation. In this work we assess the capability of the NASA GISS ModelE, coupled to MATRIX aerosol microphysics, in correctly representing warm-phase aerosol-cloud interactions. This evaluation is completed through the analysis of a nudged, multi-year global simulation using measurements from various US Department of Energy sponsored measurement campaigns and satellite-based observations. Campaign observations include the Aerosol Intensive Operations Period (Aerosol IOP) and Routine ARM Arial Facility Clouds with Low Optical Water Depths (CLOWD) Optical Radiative Observations (RACORO) at the Southern Great Plains site in Oklahoma, the Marine Stratus Radiation, Aerosol, and Drizzle (MASRAD) campaign at Pt. Reyes, California, and the ARM mobile facility's 2008 deployment to China. This combination of datasets provides a variety of aerosol and atmospheric conditions under which to test ModelE parameterizations. In addition to these localized comparisons, we provide the results of global evaluations completed using measurements derived from satellite remote sensors. We will provide a basic overview of simulation performance, as well as a detailed analysis of parameterizations relevant to aerosol indirect effects.

  7. The Effects of Aerosols on Intense Convective Precipitation in the Northeastern U.S.

    SciTech Connect

    Ntelekos, Alexandros A.; Smith, James S.; Donner, Leo J.; Fast, Jerome D.; Gustafson, William I.; Chapman, Elaine G.; Krajewski, Witold F.

    2009-08-03

    A fully coupled meteorology-chemistry-aerosol mesoscale model (WRF-Chem) is used to assess the effects of aerosols on intense convective precipitation over the northeastern United States. Numerical experiments are performed for three intense convective storm days and for two scenarios representing “typical” and “low” aerosol conditions. The results of the simulations suggest that increasing concentrations of aerosols can lead to either enhancement or suppression of precipitation. Quantification of the aerosol effect is sensitive to the metric used due to a shift of rainfall accumulation distribution when realistic aerosol concentrations are included in the simulations. Maximum rainfall accumulation amounts and areas with rainfall accumulations exceeding specified thresholds provide robust metrics of the aerosol effect on convective precipitation. Storms developing over areas with medium to low aerosol concentrations showed a suppression effect on rainfall independent of the meteorologic environment. Storms developing in areas of relatively high particulate concentrations showed enhancement of rainfall when there were simultaneous high values of CAPE, relative humidity and wind shear. In these cases, elevated aerosol concentrations resulted in stronger updrafts and downdrafts and more coherent organization of convection. For the extreme case, maximum rainfall accumulation differences exceeded 40 mm. The modeling results suggest that areas of the northeastern U.S. urban corridor that are close or downwind of intense sources of aerosols, could be more favorable for rainfall enhancement due to aerosols for the aerosol concentrations typical of this area.

  8. Observation of Organic Molecules at the Aerosol Surface.

    PubMed

    Wu, Yajing; Li, Wanyi; Xu, Bolei; Li, Xia; Wang, Han; McNeill, V Faye; Rao, Yi; Dai, Hai-Lung

    2016-06-16

    Organic molecules at the gas-particle interface of atmospheric aerosols influence the heterogeneous chemistry of the aerosol and impact climate properties. The ability to probe the molecules at the aerosol particle surface in situ therefore is important but has been proven challenging. We report the first successful observations of molecules at the surface of laboratory-generated aerosols suspended in air using the surface-sensitive technique second harmonic light scattering (SHS). As a demonstration, we detect trans-4-[4-(dibutylamino)styryl]-1-methylpyridinium iodide and determine its population and adsorption free energy at the surface of submicron aerosol particles. This work illustrates a new and versatile experimental approach for studying how aerosol composition may affect the atmospheric properties. PMID:27249662

  9. 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

  10. Fog and Cloud Induced Aerosol Modification Observed by AERONET

    NASA Technical Reports Server (NTRS)

    Eck, T. F.; Holben, B. N.; Reid, J. S.; Giles, D. M.; Rivas, M. A.; Singh, R. P.; Tripathi, S. N.; Bruegge, C. J.; Platnick, S. E.; Arnold, G. T.; Krotkov, N. A.; Carn, S. A.; Sinyuk, A.; Dubovik, O.; Arola, A.; Schafer, J. S.; Artaxo, P.; Smirnov, A.; Chen, H.; Goloub, P.

    2011-01-01

    Large fine mode (sub-micron radius) dominated aerosols in size distributions retrieved from AERONET have been observed after fog or low-altitude cloud dissipation events. These column-integrated size distributions have been obtained at several sites in many regions of the world, typically after evaporation of low altitude cloud such as stratocumulus or fog. Retrievals with cloud processed aerosol are sometimes bimodal in the accumulation mode with the larger size mode often approx.0.4 - 0.5 microns radius (volume distribution); the smaller mode typically approx.0.12 to aprrox.0.20 microns may be interstitial aerosol that were not modified by incorporation in droplets and/or aerosol that are less hygroscopic in nature. Bimodal accumulation mode size distributions have often been observed from in situ measurements of aerosols that have interacted with clouds, and AERONET size distribution retrievals made after dissipation of cloud or fog are in good agreement with particle sizes measured by in situ techniques for cloud-processed aerosols. Aerosols of this type and large size range (in lower concentrations) may also be formed by cloud processing in partly cloudy conditions and may contribute to the shoulder of larger size particles in the accumulation mode retrievals, especially in regions where sulfate and other soluble aerosol are a significant component of the total aerosol composition. Observed trends of increasing aerosol optical depth (AOD) as fine mode radius increased suggests higher AOD in the near cloud environment and therefore greater aerosol direct radiative forcing than typically obtained from remote sensing, due to bias towards sampling at low cloud fraction.

  11. Global Lidar Observations of Aerosol Distribution and Radiative Influence

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

    A very visible impact of human activities is the brownish aerosol haze that pervades many industrialized regions as well as areas in the subtropics and tropics where biomass burning occurs. Well known examples are the Asian Brown Cloud, Arctic Haze and East Coast Haze. Atmospheric transport transforms this haze into regional and hemispheric aerosol layers of significant concentrations. The overall impact on the radiation balance of the atmosphere, surface solar irradiance and other meteorology factors is recognized as a major uncertainty for climate change. In order to understand the impact, the global distribution of aerosol and their properties must be known. . A missing element of observations, but critical for understanding transport has been the height distribution of aerosol. Lidar measurements of aerosol height distribution have been important in GLOBE, ACE, INDOEX and other field studies A network of continuously operating eye safe lidar ground sites has now been established for baseline aerosol profiling. In 2002 NASA will launch the Geoscience Laser Altimeter System (GLAS) mission which will provide for the first time global observations of the height distribution of aerosol. The combination of these and other modem satellite observations, field experiments and models of global aerosol composition and transport should begin to unravel the impacts of particles in the atmosphere.

  12. Retrieval of Aerosol Absorption Properties from Satellite Observations

    NASA Technical Reports Server (NTRS)

    Torres, Omar; Bhartia, Pawan K.; Jethva, H.; Ahn, Chang-Woo

    2012-01-01

    The Angstrom Absorption Exponent (AAE) is a parameter commonly used to characterize the wavelength-dependence of aerosol absorption optical depth (AAOD). It is closely related to aerosol composition. Black carbon (BC) containing aerosols yield AAE values near unity whereas Organic carbon (OC) aerosol particles are associated with values larger than 2. Even larger AAE values have been reported for desert dust aerosol particles. Knowledge of spectral AAOD is necessary for the calculation of direct radiative forcing effect of aerosols and for inferring aerosol composition. We have developed a satellitebased method of determining the spectral AAOD of absorbing aerosols. The technique uses multi-spectral measurements of upwelling radiation from scenes where absorbing aerosols lie above clouds as indicated by the UV Aerosol Index. For those conditions, the satellite measurement can be explained, using an approximations of Beer's Law (BL), as the upwelling reflectance at the cloud top attenuated by the absorption effects of the overlying aerosol layer. The upwelling reflectance at the cloud-top in an aerosol-free atmospheric column is mainly a function of cloud optical depth (COD). In the proposed method of AAE derivation, the first step is determining COD which is retrieved using a previously developed color-ratio based approach. In the second step, corrections for molecular scattering effects are applied to both the observed ad the calculated cloud reflectance terms, and the spectral AAOD is then derived by an inversion of the BL approximation. The proposed technique will be discussed in detail and application results making use of OMI multi-spectral measurements in the UV-Vis. will be presented.

  13. Multi-satellite aerosol observations in the vicinity of clouds

    NASA Astrophysics Data System (ADS)

    Várnai, T.; Marshak, A.; Yang, W.

    2013-04-01

    Improved characterization of aerosol properties in the vicinity of clouds is important for better understanding two critical aspects of climate: aerosol-cloud interactions and the direct radiative effect of aerosols. Satellite measurements have provided important insights into aerosol properties near clouds, but also suggested that the observations can be affected by 3-D radiative processes and instrument blurring not considered in current data interpretation methods. This study examines systematic cloud-related changes in particle properties and radiation fields that influence satellite measurements of aerosols in the vicinity of low-level maritime clouds. For this, the paper presents a statistical analysis of a yearlong global dataset of co-located MODIS and CALIOP observations and theoretical simulations. The results reveal that CALIOP-observed aerosol particle size and optical thickness, and MODIS-observed solar reflectance increase systematically in a wide transition zone around clouds. It is estimated that near-cloud changes in particle populations - including both aerosols and undetected cloud particles - are responsible for roughly two thirds of the observed increase in 0.55 μm MODIS reflectance. The results also indicate that 3-D radiative processes significantly contribute to near-cloud reflectance enhancements, while instrument blurring contributes significantly only within 1 km from clouds and then quickly diminishes with distance from clouds.

  14. Nabro aerosol evolution observed jointly by lidars at a mid-latitude site and CALIPSO

    NASA Astrophysics Data System (ADS)

    Zhuang, J.; Yi, F.

    2016-09-01

    Evolution of the Nabro volcanic aerosols from initially-localized plumes to a decaying hemispherically-covered layer was jointly observed by ground-based lidars at Wuhan (30.5°N, 114.4°E), China and CALIPSO. During the aerosol plume formation period, from the Nabro eruption to early July 2011, the lidar backscatter ratio related to the Nabro aerosols above Wuhan varied strongly both in vertical structure and intensity, suggesting that the Nabro aerosol distribution was horizontally inhomogeneous. The stratospheric aerosol optical depth (AOD) from CALIPSO shows that the Nabro plume first circled around the Asian monsoon anticyclone and then gradually fulfilled the whole anticyclone area with a net aerosol enhancement, which may reflect a gas-particle conversion (from sulfur dioxide gas) and/or particle injection from the upper troposphere. During the horizontal dispersion period, from early July to mid-August 2011, the stratospheric AOD over Wuhan declined rapidly since the Nabro particles were transported throughout the northern hemisphere. A nearly horizontally-uniform volcanic aerosol layer was formed. During the local cleansing period, from mid-August to the end of 2011, the Nabro aerosol layer over Wuhan had a single-peak structure and decayed uniformly. The corresponding e-folding decay time for the layer AOD is ∼130 days. The lidar measurements at Wuhan gave a small depolarization ratio and large backscatter-related Ångström exponent for the Nabro aerosols on 8 July, suggesting that the majority of these aerosols were spherical and small. The effective radius and total mass for the Nabro aerosol particles were estimated to be ∼0.26 μm and ∼0.32 Tg respectively.

  15. Satellite and ground-based remote sensing of aerosols during intense haze event of October 2013 over lahore, Pakistan

    NASA Astrophysics Data System (ADS)

    Tariq, Salman; Zia, ul-Haq; Ali, Muhammad

    2016-02-01

    Due to increase in population and economic development, the mega-cities are facing increased haze events which are causing important effects on the regional environment and climate. In order to understand these effects, we require an in-depth knowledge of optical and physical properties of aerosols in intense haze conditions. In this paper an effort has been made to analyze the microphysical and optical properties of aerosols during intense haze event over mega-city of Lahore by using remote sensing data obtained from satellites (Terra/Aqua Moderate-resolution Imaging Spectroradiometer (MODIS) and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO)) and ground based instrument (AErosol RObotic NETwork (AERONET)) during 6-14 October 2013. The instantaneous highest value of Aerosol Optical Depth (AOD) is observed to be 3.70 on 9 October 2013 followed by 3.12 on 8 October 2013. The primary cause of such high values is large scale crop residue burning and urban-industrial emissions in the study region. AERONET observations show daily mean AOD of 2.36 which is eight times higher than the observed values on normal day. The observed fine mode volume concentration is more than 1.5 times greater than the coarse mode volume concentration on the high aerosol burden day. We also find high values (~0.95) of Single Scattering Albedo (SSA) on 9 October 2013. Scatter-plot between AOD (500 nm) and Angstrom exponent (440-870 nm) reveals that biomass burning/urban-industrial aerosols are the dominant aerosol type on the heavy aerosol loading day over Lahore. MODIS fire activity image suggests that the areas in the southeast of Lahore across the border with India are dominated by biomass burning activities. A Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model backward trajectory showed that the winds at 1000 m above the ground are responsible for transport from southeast region of biomass burning to Lahore. CALIPSO derived sub-types of

  16. Aerosol optical depth retrieval using the MERIS observation

    NASA Astrophysics Data System (ADS)

    Mei, Linlu; Rozanov, Vladimir; Vountas, Marco; Burrows, John P.

    2015-04-01

    Surface reflectance determination and aerosol type selection are the two main challenges for space-borne aerosol remote sensing, especially for those instruments lacking of near-infrared channels, high-temporal observations, multi-angles abilities and/or polarization information. However, space based instruments like the MEdium Resolution Imaging Spectrometer (MERIS) and the successor, Ocean and Land Colour Instrument (OLCI) with high calibration accuracy and high spatial resolution provide unique abilities for obtaining valuable aerosol information for a better understanding of the impact of aerosols on climate, which is still one of the largest uncertainties of global climate change evaluation. In this study, a new Aerosol Optical Depth (AOD) retrieval algorithm is presented. Global aerosol type and surface spectral dataset were used for the aerosol type selection and surface reflectance determination. A modified Ross-Li mode is used to describe the surface Bidirectional Reflectance Distribution Function (BRDF) effect. The comparison with operational MODIS C6 product and the validation using AErosol RObotic NETwork (AERONET) show promising results.

  17. Biogenic Contributions to Summertime Arctic Aerosol: Observations of Aerosol Composition from the Netcare 2014 Aircraft Campaign

    NASA Astrophysics Data System (ADS)

    Willis, M. D.; Burkart, J.; Koellner, F.; Schneider, J.; Bozem, H.; Hoor, P. M.; Brauner, R.; Herber, A. B.; Leaitch, W. R.; Abbatt, J.

    2014-12-01

    The Arctic is a complex and poorly studied aerosol environment, impacted by strong anthropogenic contributions during winter months and by regional sources in cleaner summer months. In order to gain a predictive understanding of the changing climate in this region, it is necessary to understand the balance between these two aerosol sources to clarify how aerosol might be altered by or contribute to climate change. We present results of vertically resolved, submicron aerosol composition from an Aerodyne high-resolution aerosol mass spectrometer (AMS) during the NETCARE 2014 Polar6 aircraft campaign. The campaign was based in the high Arctic, at Resolute, NU (74°N), allowing measurements from 60 to 2900 meters over ice, open water and near the ice-edge. Concurrent measurements aboard the Polar6 included ultrafine and accumulation mode particle number and size, cloud condensation nuclei concentrations, trace gas concentrations and single particle composition. Aerosol vertical profiles measured by the AMS can be broadly characterized into two regimes corresponding to different meteorological conditions: the first with very low aerosol loading (<0.1 μg/m3) at low altitudes compared to that aloft and high numbers of nucleation mode particles, and the second with higher concentrations at lower levels. This second regime was associated with low concentrations of nucleation mode particles, and higher observable levels of methane sulphonic acid (MSA) from AMS measurements at low altitudes. MSA, produced during the oxidation of dimethyl sulphide, is a marker for the contribution of ocean-derived biogenic sulphur to particulate sulphur and could be identified and quantified using the high-resolution AMS. MSA to sulphate ratios were observed to increase towards lower altitudes, suggesting a contribution to aerosol loading from the ocean. In addition, we present measurements of aerosol neutralization and the characteristics of organic aerosol that relate to the growth of

  18. Potential indirect effects of aerosol on tropical cyclone intensity: convective fluxes and cold-pool activity

    NASA Astrophysics Data System (ADS)

    Krall, G. M.; Cottom, W. R.

    2012-01-01

    Observational and model evidence suggest that a 2008 Western Pacific typhoon (NURI) ingested elevated concentrations of aerosol as it neared the Chinese coast. This study uses a regional model with two-moment bin-emulating microphysics to simulate the typhoon as it enters the field of elevated aerosol concentrations. A clean maritime field of cloud condensation nuclei (CCN) was prescribed as marine background CCN concentrations and then based on satellite and global aerosol model output, increased to pollution levels and further enhanced in sensitivity tests. The typhoon was simulated for 96 h beginning 17 August 2008. During the final 60 h CCN concentrations were enhanced as it neared the Philippines and coastal China. The model was initialized with both global reanalysis model data and irregularly spaced dropsonde data from the 2008 T-PARC observational campaign using an objective analysis routine. At 36 h, the internal nudging of the model was switched off and allowed to freely evolve on its own. As the typhoon encountered the elevated CCN in the sensitivity tests, a significant perturbation of windspeed, convective fluxes, and hydrometeor species behavior was simulated. Early during the ingestion of enhanced CCN, precipitation was reduced due to suppressed collision and coalescence, and storm winds increased in strength. Subsequently, owing to reduced fall speeds of the smaller drops, greater amounts of condensate were thrust into supercooled levels where the drops froze releasing greater amounts of latent heat of freezing. Convection thereby intensified which resulted in enhanced rainfall and more vigorous convectively-produced downdrafts. As the convection intensified in the outer rainbands the storm drifted over the developing cold-pools. The enhanced cold-pools blocked the inflow of warm, moist air into the core of the typhoon which led to a weakening of the typhoon with significantly reduced low level wind speeds. The very high amounts of pollution

  19. Amazon basin ozone and aerosol: Wet season observations

    SciTech Connect

    Gregory, G.L.; Browell, E.V.; Warren, L.S.; Hudgins, C.H. )

    1990-09-20

    The tropical environment is recognized as having a major impact on global tropospheric chemistry. The data show that the wet season Amazon Basin is an effective sink for ozone and a net source for aerosols. Mixed layer ozone at 150-m altitude averaged 8.5 ppbv compared to about 18 ppbv at 3-km altitude. In addition, a negative ozone gradient (decreasing value to the surface) was observed within the mixed layer. The averaged wet season mixed layer ozone was about 7 ppbv lower than observed during the dry season. This is attributed to the enhanced convective activity associated with the wet season and the change in mixed layer photochemistry from net ozone production (dry season) to a net destruction (wet season). The net sink characteristics of the wet season mixed layer are seen throughout the troposphere of the Amazon Basin in that ozone (3- to 4-km altitude) is typically 15-25 ppbv as compared to dry season values of 30-35 ppbv. In terms of the aerosol source characteristics of the Amazon Basin, mixed layer aerosols (0.1- to 0.4-{mu}m diameter) are a factor of 5-10 higher than observed in the troposphere with mixed layer values of 100-200 aerosols/cm{sup 3}. Analyses of both tropospheric and mixed layer aerosol samples show aerosols which are multisource. Tropospheric samples have size distributions which are trimodal and show modes at aerosol diameters which suggest the aerosols are (1) of lifetimes <1 hour, (2) of lifetimes of days, and (3) mechanically generated elements (e.g., wind-blow dust). Mixed layer data show two of the three modes with no mode which represent aerosols with lifetimes of days.

  20. Retrieval of Stratospheric Aerosol Properties from SCIAMACHY limb observations

    NASA Astrophysics Data System (ADS)

    Dörner, S.; Kühl, S.; Pukite, J.; Penning de Vries, M.; Hörmann, C.; von Savigny, C.; Wagner, T.

    2012-04-01

    Balloon-borne and aircraft measurements of stratospheric aerosol properties have been supplemented by satellite measurements since 1975 (Stratospheric Aerosol Measurement program). Ever since, the technological possibilities of satellite measurements increased steadily. Nowadays the large number of satellites provides global data sets of trace gases, clouds and aerosols. Stratospheric aerosol properties are usually determined from observations in occultation or limb geometry. Stratospheric aerosol has an important influence on the global radiation budget (e.g. after strong volcanic eruptions) and stratospheric ozone chemistry (e.g. the chlorine activation inside the polar vortex). Since the launch of SCIAMACHY on ENVISAT in 2002 measurements in limb geometry for the UV/VIS/NIR spectral range with a vertical resolution of 3.3 km at the tangent point are available. By using these measurements, profile information of stratospheric trace gases (e.g. NO2, BrO or OClO) can be retrieved. From the broad band spectral dependence of the SCIAMACHY limb measurements, also information on stratospheric aerosol properties can be derived. Pioneering studies (e.g. von Savigny et al., 2005) showed that signatures of polar stratospheric clouds and also stratospheric aerosols can be retrieved from color indices (including the near IR spectral range). In our study we make use of the color index method and additionally investigate the effects of aerosols on the whole UV/VIS/NIR spectral range. Aerosol properties are estimated by comparisons of the measured values with radiative transfer simulations. We investigate different atmospheric phenomena, e.g. volcanic eruptions (e.g. Kasatochi, 2008) or large biomass burning events (e.g. Australia, 2009). We also have a look at the spatio-temporal variation of Polar Stratospheric Clouds in the polar regions and stratospheric aerosol properties on a global scale.

  1. Stratospheric aerosols on Jupiter from Cassini observations

    NASA Astrophysics Data System (ADS)

    Zhang, X.; West, R. A.; Banfield, D.; Yung, Y. L.

    2013-09-01

    We retrieved global distributions and optical properties of stratospheric aerosols on Jupiter from ground-based NIR spectra and multiple-phase-angle images from Cassini Imaging Science Subsystem (ISS). A high-latitude haze layer is located at ∼10-20 mbar, higher than in the middle and low latitudes (∼50 mbar). Compact sub-micron particles are mainly located in the low latitudes between 40°S and 25°N with the particle radius between 0.2 and 0.5 μm. The rest of the stratosphere is covered by the particles known as fractal aggregates. In the nominal case with the imaginary part of the UV refractive index 0.02, the fractal aggregates are composed of about a thousand 10-nm-size monomers. The column density of the aerosols at pressure less than 100 mbar ranges from ∼107 cm-2 at low latitudes to ∼109 cm-2 at high latitudes. The mass loading of aerosols in the stratosphere is ∼10-6 g cm-2 at low latitudes to ∼10-4 g cm-2 in the high latitudes. Multiple solutions due to the uncertainty of the imaginary part of the refractive index are discussed. The stratospheric haze optical depths increase from ∼0.03 at low latitudes to about a few at high latitudes in the UV wavelength (∼0.26 μm), and from ∼0.03 at low latitudes to ∼0.1 at high latitudes in the NIR wavelength (∼0.9 μm).

  2. THEMIS Observations of Atmospheric Aerosol Optical Depth

    NASA Technical Reports Server (NTRS)

    Smith, Michael D.; Bandfield, Joshua L.; Christensen, Philip R.; Richardson, Mark I.

    2003-01-01

    The Mars Odyssey spacecraft entered into Martian orbit in October 2001 and after successful aerobraking began mapping in February 2002 (approximately Ls=330 deg.). Images taken by the Thermal Emission Imaging System (THEMIS) on-board the Odyssey spacecraft allow the quantitative retrieval of atmospheric dust and water-ice aerosol optical depth. Atmospheric quantities retrieved from THEMIS build upon existing datasets returned by Mariner 9, Viking, and Mars Global Surveyor (MGS). Data from THEMIS complements the concurrent MGS Thermal Emission Spectrometer (TES) data by offering a later local time (approx. 2:00 for TES vs. approx. 4:00 - 5:30 for THEMIS) and much higher spatial resolution.

  3. 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.

  4. PARAGON: A Systematic, Integrated Approach to Aerosol Observation and Modeling

    NASA Technical Reports Server (NTRS)

    Diner, David J.; Kahn, Ralph A.; Braverman, Amy J.; Davies, Roger; Martonchik, John V.; Menzies, Robert T.; Ackerman, Thomas P.; Seinfeld, John H.; Anderson, Theodore L.; Charlson, Robert J.; Bosenberg, Jens; Collins, William D.; Rasch, Philip J.; Holben, Brent N.; Hostetler, Chris A.; Wielicki, Bruce A.; Miller, Mark A.; Schwartz, Stephen E.; Ogren, John A.; Penner, Joyce E.; Stephens, Graeme L.; Torres, Omar; Travis, Larry D.; Yu, Bin

    2004-01-01

    Aerosols are generated and transformed by myriad processes operating across many spatial and temporal scales. Evaluation of climate models and their sensitivity to changes, such as in greenhouse gas abundances, requires quantifying natural and anthropogenic aerosol forcings and accounting for other critical factors, such as cloud feedbacks. High accuracy is required to provide sufficient sensitivity to perturbations, separate anthropogenic from natural influences, and develop confidence in inputs used to support policy decisions. Although many relevant data sources exist, the aerosol research community does not currently have the means to combine these diverse inputs into an integrated data set for maximum scientific benefit. Bridging observational gaps, adapting to evolving measurements, and establishing rigorous protocols for evaluating models are necessary, while simultaneously maintaining consistent, well understood accuracies. The Progressive Aerosol Retrieval and Assimilation Global Observing Network (PARAGON) concept represents a systematic, integrated approach to global aerosol Characterization, bringing together modern measurement and modeling techniques, geospatial statistics methodologies, and high-performance information technologies to provide the machinery necessary for achieving a comprehensive understanding of how aerosol physical, chemical, and radiative processes impact the Earth system. We outline a framework for integrating and interpreting observations and models and establishing an accurate, consistent and cohesive long-term data record.

  5. Synergy of Satellite-Surface Observations for Studying the Properties of Absorbing Aerosols in Asia

    NASA Technical Reports Server (NTRS)

    Tsay, Si-Chee

    2010-01-01

    Through interaction with clouds and alteration of the Earth's radiation budget, atmospheric aerosols significantly influence our weather and climate. Monsoon rainfalls, for example, sustain the livelihood of more than half of the world's population. Thus, understanding the mechanism that drives the water cycle and freshwater distribution is high-lighted as one of the major near-term goals in NASA's Earth Science Enterprise Strategy. Every cloud droplet/ice-crystal that serves as an essential element in portraying water cycle and distributing freshwater contains atmospheric aerosols at its core. In addition, the spatial and temporal variability of atmospheric aerosol properties is complex due to their dynamic nature. In fact, the predictability of the tropical climate system is much reduced during the boreal spring, which is associated with the peak season of biomass burning activities and regional/long-range transport of dust aerosols. Therefore, to accurately assess the impact of absorbing aerosols on regional-to-global climate requires not only modeling efforts but also continuous observations from satellites, aircraft, networks of ground-based instruments and dedicated field experiments. Since 1997 NASA has been successfully launching a series of satellites the Earth Observing System - to intensively study, and gain a better understanding of, the Earth as an integrated system. Through participation in many satellite remote-sensing/retrieval and validation projects over the years, we have gradually developed and refined the SMART (Surface-sensing Measurements for Atmospheric Radiative Transfer) and COMMIT (Chemical, Optical & Microphysical Measurements of In-situ Troposphere) mobile observatories, a suite of surface remote sensing and in-situ instruments that proved to be vital in providing high temporal measurements, which complement the satellite observations. In this talk, we will present SMART-COMMIT which has played key roles, serving as network or supersite

  6. The Stratospheric Aerosol and Gas Experiment III - International Space Station: Extending Long-Term Ozone and Aerosol Observations (Invited)

    NASA Astrophysics Data System (ADS)

    Eckman, R.; Zawodny, J. M.; Cisewski, M.; Gasbarre, J.; Flittner, D. E.; Hill, C.; Roell, M.; Moore, J. R.; Hernandez, G.; McCormick, M. P.

    2013-12-01

    The Stratospheric Aerosol and Gas Experiment III - International Space Station (SAGE III on ISS) will extend the global measurements of vertical profiles of ozone, aerosols, water vapor, nitrogen dioxide, and other trace gases begun with SAGE I in 1979, enabling the detection of long-term trends. SAGE III on ISS is the fourth in a series of instruments developed for monitoring these constituents in the stratosphere and troposphere. The SAGE III instrument is a moderate resolution spectrometer covering wavelengths from 290 nm to 1550 nm, using the heritage occultation technique, utilizing both the sun and the moon. Launch to ISS is planned for early 2015 aboard a Falcon 9 spacecraft. SAGE III will investigate the spatial and temporal variability of the measured species in order to determine their role in climatological processes, biogeochemical cycles, the hydrologic cycle, and atmospheric chemistry. It will characterize tropospheric, as well as stratospheric aerosols and upper tropospheric and stratospheric clouds, and investigate their effects on the Earth's environment including radiative, microphysical, and chemical interactions. The multi-decadal SAGE ozone and aerosol data sets have undergone intense scrutiny and are the international standard for accuracy and stability. SAGE data have been used to monitor the effectiveness of the Montreal Protocol. Amongst its key objectives will be to assess the state of the recovery in the distribution of ozone, to reestablish the aerosol measurements needed by both climate and ozone models, and to gain further insight into key processes contributing to ozone and aerosol variability. The ISS is ideal for Earth observing experiments; its mid-inclination orbit allows for a large range in latitude sampling and nearly continuous communications with payloads. In this presentation, we describe the SAGE III on ISS mission, its implementation, current status, and concentrate on its key science objectives.

  7. The stratospheric sulfate aerosol layer - Processes, models, observations, and simulations

    NASA Technical Reports Server (NTRS)

    Whitten, R. C.; Toon, O. B.; Turco, R. P.

    1980-01-01

    After briefly reviewing the observational data on the stratospheric sulfate aerosol layer, the chemical and physical processes that are likely to fix the properties of the layer are discussed. We present appropriate continuity equations for aerosol particles, and show how to solve the equations on a digital computer. Simulations of the unperturbed aerosol layer by various published models are discussed and the sensitivity of layer characteristics to variations in several aerosol model parameters is studied. We discuss model applications to anthropogenic pollution problems and demonstrate that moderate levels of aerospace activity (supersonic transport and Space Shuttle operations) will probably have only a negligible effect on global climate. Finally, we evaluate the possible climatic effect of a ten-fold increase in the atmospheric abundance of carbonyl sulfide.

  8. Radiative Impact of Observed and Simulated Aerosol Layers Over the East Coast of North America

    NASA Astrophysics Data System (ADS)

    Berg, L. K.; Fast, J. D.; Burton, S. P.; Chand, D.; Comstock, J. M.; Ferrare, R. A.; Hair, J. W.; Hostetler, C. A.; Hubbe, J. M.; Kassianov, E.; Rogers, R. R.; Sedlacek, A. J., III; Shilling, J. E.; Tomlinson, J. M.; Wilson, J. M.; Zelenyuk, A.

    2014-12-01

    The vertical distribution of particles in the atmospheric column can have a large impact on the radiative forcing and cloud microphysics. A recent climatology constructed using data collected by the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) suggests elevated layers of aerosol are quite common near the North American east coast during both winter and summer. The Two-Column Aerosol Project (TCAP), conducted from June 2012 through June 2013, was a unique study utilizing both in situ and remotely sensed measurements designed to provide a comprehensive data set that can be used to investigate science questions related to aerosol radiative forcing and the vertical distribution of aerosol. The study sampled the atmosphere at a number of altitudes within two atmospheric columns; one located near the coast of North America (over Cape Cod, MA) and a second over the Atlantic Ocean several hundred kilometers from the coast. TCAP included the yearlong deployment of the U.S. Department of Energy's Atmospheric Radiation Measurement (ARM) Mobile Facility (AMF) located at the base of the Cape Cod column, as well as summer and winter aircraft intensive observation periods (IOPs) using the ARM Aerial Facility. One important finding from the TCAP summer IOP is the relatively common occurrence (during four of the six nearly cloud-free flights) of elevated aerosol layers in both the Cape Cod and maritime columns that were detected using the nadir pointing second-generation NASA Langley Research Center High-Spectral Resolution Lidar (HSRL-2). These elevated layers contributed up to 60% of the total observed aerosol optical depth (AOD). Many of these layers were also intercepted by the aircraft configured for in situ sampling, and the aerosol in the layers was found to have increased amounts of biomass burning material and nitrate compared to aerosol found near the surface. Both the in situ and remote sensing observations have been compared to

  9. Characterization of aerosol episodes in the greater Mediterranean Sea area from satellite observations (2000-2007)

    NASA Astrophysics Data System (ADS)

    Gkikas, A.; Hatzianastassiou, N.; Mihalopoulos, N.; Torres, O.

    2016-03-01

    An algorithm able to identify and characterize episodes of different aerosol types above sea surfaces of the greater Mediterranean basin (GMB), including the Black Sea and the Atlantic Ocean off the coasts of Iberia and northwest Africa, is presented in this study. Based on this algorithm, five types of intense (strong and extreme) aerosol episodes in the GMB are identified and characterized using daily aerosol optical properties from satellite measurements, namely MODIS-Terra, Earth Probe (EP)-TOMS and OMI-Aura. These aerosol episodes are: (i) biomass-burning/urban-industrial (BU), (ii) desert dust (DD), (iii) dust/sea-salt (DSS), (iv) mixed (MX) and (v) undetermined (UN). The identification and characterization is made with our algorithm using a variety of aerosol properties, namely aerosol optical depth (AOD), Ångström exponent (α), fine fraction (FF), effective radius (reff) and Aerosol Index (AI). During the study period (2000-2007), the most frequent aerosol episodes are DD, observed primarily in the western and central Mediterranean Sea, and off the northern African coasts, 7 times/year for strong episodes and 4 times/year for extreme ones, on average. The DD episodes yield 40% of all types of strong aerosol episodes in the study region, while they account for 71.5% of all extreme episodes. The frequency of occurrence of strong episodes exhibits specific geographical patterns, for example the BU are mostly observed along the coasts of southern Europe and off the Atlantic coasts of Portugal, the MX episodes off the Spanish Mediterranean coast and over the Adriatic and northern Aegean Sea, while the DSS ones over the western and central Mediterranean Sea. On the other hand, the extreme episodes for all but DD aerosol display more patchy spatial patterns. The strong episodes exhibit AOD at 550 nm as high as 1.6 in the southernmost parts of central and eastern Mediterranean Sea, which rise up to 5 for the extreme, mainly DD and DSS, episodes. Although more

  10. Distribution of Aerosols in the Arctic as Observed by CALIOP

    NASA Astrophysics Data System (ADS)

    Winker, D.; Kittaka, C.

    2007-12-01

    The Arctic climate is now recognized to be uniquely sensitive to atmospheric perturbations. Pollution aerosols and smoke from boreal fires have potentially important impacts on Arctic climate but there are many uncertainties. Aerosol in the Arctic, generally referred to as "Arctic haze", has been studied with great interest for over thirty years. Much has been learned about the composition and sources of the haze yet our knowledge is largely based on long term measurements at a very few widely dispersed sites, augmented by modeling activities and occasional field campaigns. Transport pathways from source regions into the Arctic are not well understood. Emission patterns have changed over the last several decades, but the impact of this on concentrations and distribution of Arctic haze are understood only in the crudest sense. Due to poor lighting conditions, extended periods of darkness, and surfaces covered by snow and ice, satellite sensors have been unable to provide much information on Arctic haze to date. The CALIPSO satellite carries CALIOP, a two-wavelength polarization lidar, optimized for profiling clouds and aerosols. CALIOP has been acquiring global observations since June 2006 and provides our first opportunity to observe the distribution and seasonal variation of aerosol in the Arctic. The Arctic is characterized by the prevalence of optically thin ice clouds and clouds composed of supercooled water, often occurring in the same atmospheric column along with aerosol. CALIOP depolarization signals are used to discriminate Arctic haze from optically thin cirrus and diamond dust. Two-wavelength returns aid in the discrimination of aerosol and optically thin water cloud. Results of initial analyses of CALIOP aerosol observations in the Arctic will be presented. This work is a preliminary analysis in support of the NASA Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) field campaign planned for April 2008.

  11. Retrieval of Stratospheric Aerosol Properties from SCIAMACHY limb observations

    NASA Astrophysics Data System (ADS)

    Doerner, S.; Kühl, S.; Pukite, J.; Penning de Vries, M. J.; Hoermann, C.; von Savigny, C.; Deutschmann, T.; Wagner, T.

    2012-12-01

    Since the start of the Stratospheric Aerosol Measurement program in 1975 satellites have been improving our understanding of the global distribution of trace gases, clouds and aerosols. Observations in occultation and limb geometry provide profile information on stratospheric aerosol, which have an important influence on the global radiation budget (e.g., after strong volcanic eruptions) and the stratospheric ozone chemistry (e.g., the chlorine activation inside the polar vortex). The Scanning Imaging Absorption Spectrometer for Atmospheric CHartographY (SCIAMACHY) on ENVISAT performed measurements in limb geometry for almost ten years between 2002 and 2012. Its vertical resolution of about 3.3 km at the tangent point and the broad spectral range (UV/VIS/NIR) allow to retrieve profile information of stratospheric trace gases (e.g., O3, NO2, BrO or OClO) and stratospheric aerosol properties. Pioneering studies (e.g., Savigny et al., 2005) showed that in particular from color indices (including the near IR spectral range) signatures of stratospheric aerosols and polar stratospheric clouds (PSCs) can be retrieved. In our study we investigate the sensitivity of SCIAMACHY's broad spectral range to aerosol particle properties by comparing measured spectra with simulated results from the 3D full spherical Monte Carlo Atmospheric Radiative Transfer Model McArtim. In particular, we focus on the absorption properties in the UV spectral range, the extinction coefficient and the Angström exponent. The final aim of our study is to use SCIAMACHY limb measurements for the profile retrieval of optical parameters (e.g., absorption and phase function) from which microphysical properties (e.g., mean aerosol particle diameter) of the stratospheric aerosol particles can be deduced.

  12. Observed changes in aerosol physical and optical properties before and after precipitation events

    NASA Astrophysics Data System (ADS)

    Li, Xingmin; Dong, Yan; Dong, Zipeng; Du, Chuanli; Chen, Chuang

    2016-08-01

    Precipitation scavenging of aerosol particles is an important removal process in the atmosphere that can change aerosol physical and optical properties. This paper analyzes the changes in aerosol physical and optical properties before and after four rain events using in situ observations of mass concentration, number concentration, particle size distribution, scattering and absorption coefficients of aerosols in June and July 2013 at the Xianghe comprehensive atmospheric observation station in China. The results show the effect of rain scavenging is related to the rain intensity and duration, the wind speed and direction. During the rain events, the temporal variation of aerosol number concentration was consistent with the variation in mass concentration, but their size-resolved scavenging ratios were different. After the rain events, the increase in aerosol mass concentration began with an increase in particles with diameter <0.8 μm [measured using an aerodynamic particle sizer (APS)], and fine particles with diameter <0.1 μm [measured using a scanning mobility particle sizer (SMPS)]. Rainfall was most efficient at removing particles with diameter ~0.6 μm and greater than 3.5 μm. The changes in peak values of the particle number distribution (measured using the SMPS) before and after the rain events reflect the strong scavenging effect on particles within the 100-120 nm size range. The variation patterns of aerosol scattering and absorption coefficients before and after the rain events were similar, but their scavenging ratios differed, which may have been related to the aerosol particle size distribution and chemical composition.

  13. Aerosol observations and growth rates in the tropical tropopause layer

    NASA Astrophysics Data System (ADS)

    Waddicor, D. A.; Vaughan, G.; Choularton, T. W.; Bower, K. N.; Coe, H.; Gallagher, M.; Williams, P. I.; Flynn, M.; Volz-Thomas, A.; Pätz, W.; Isaac, P.; Hacker, J.; Arnold, F.; Schlager, H.; Whiteway, J. A.

    2012-01-01

    We present a case study of Aitken and accumulation mode aerosol observed downwind of the anvils of deep tropical thunderstorms. The measurements were made by condensation nuclei counters flown on the Egrett high-altitude aircraft from Darwin during the ACTIVE campaign, in monsoon conditions producing widespread convection over land and ocean. Maximum measured concentrations of aerosol in the size range 10-100 nm were 25 000 cm-3 STP. By calculating back-trajectories from the observations, and projecting on to infrared satellite images, the time since the air exited cloud was estimated. In this way a time scale of ~ 3-4 h was derived for the 10-100 nm aerosol concentration to reach its peak. We examine the hypothesis that the growth in aerosol concentrations can be explained by production of sulphuric acid from SO2 followed by particle nucleation and coagulation. Estimates of the sulphuric acid production rate show that the observations are only consistent with this hypothesis if the particles coagulate to sizes > 10 nm much more quickly than is suggested by current theory. Alternatively, other condensible gases (possibly organic) drive the growth of aerosol particles in the TTL.

  14. Observational constraints for climate forcing by biomass burning aerosols

    NASA Astrophysics Data System (ADS)

    Penner, J. E.; Zhou, C.; Prather, M. J.; Xu, L.

    2012-12-01

    Estimates of sources of aerosols from open biomass burning vary to a significant extent, and those for pre-industrial emissions are even more uncertain. Previously, we showed how the use of a global chemical transport model together with TOMS satellite data for aerosol index and black carbon (BC) concentrations in ice-cores can be used to constrain present-day (PD) (year 2000) and pre-industrial (PI) (year 1870) emissions. The total aerosol forcing (direct and warm cloud indirect) from these emissions was estimated to be -0.065 W m-2, although values as large as -0.21 W m-2 could not be excluded. Here, we further examine the consistency between our estimates of biomass burning sources and observations of the spectrally varying AAOD from AERONET. We present adjusted estimates that also include these observations.

  15. SPICAV-SOIR mesospheric aerosols observations characterization and modelling

    NASA Astrophysics Data System (ADS)

    Wilquet, V.; Piccialli, A.; Vandaele, A. C.; Montmessin, F.; Bertaux, J. L.

    2013-09-01

    From independent retrievals for the 3 channels of the SPICAV/SOIR instrument, it has been postulated that the upper haze on Venus includes, in some instances, a bimodal population, one type of particles with a radius comprised between ~0.1 and 0.3 μm and the second type, detected in the IR, with a radius varying between ~0.4 and 1 μm. In addition, a high temporal variability in the aerosol loading was inferred from SOIR observations over 4 years, as well as a latitudinal dependency. We propose to refine the size distribution retrieval of aerosols based on the Mie theory and on the observed spectral dependence of light extinction in the spectra through a unique retrieval procedure combining the data from the 3 channels of the instrument. We also search for a dependence on altitude of the aerosol particles size distribution and of aerosol composition and compare the variations in aerosol loading to other key parameters retrieved such as water and SO2 composition or temperature.

  16. Pathfinder Instruments for Cloud and Aerosol Spaceborne Observations (PICASSO)

    NASA Technical Reports Server (NTRS)

    McCormick, M. Patrick; Winker, David M.

    1998-01-01

    This paper will describe the planned 3-year Pathfinder Instruments for Cloud and Aerosol Spaceborne Observations (PICASSO) mission, its instrumentation and implementation. It will use LITE and other data, plus analyses, to show the feasibility of such a mission. PICASSO is being proposed for NASA's Earth System Science Pathfinder (ESSP) program with launch predicted in 2003.

  17. Multi-year Satellite and Surface Observations of AOD in support of Two-Column Aerosol Project (TCAP) Field Campaign

    SciTech Connect

    Kassianov, Evgueni I.; Chand, Duli; Berg, Larry K.; Fast, Jerome D.; Tomlinson, Jason M.; Ferrare, R.; Hostetler, Chris A.; Hair, John

    2012-11-01

    We use combined multi-year measurements from the surface and space for assessing the spatial and temporal distribution of aerosol properties within a large (~400x400 km) region centered on Cape Cod, Massachusetts, along the East Coast of the United States. The ground-based Aerosol Robotic Network (AERONET) measurements at Martha’s Vineyard Coastal Observatory (MVCO) site and Moderate Resolution Imaging Spectrometer (MODIS) sensors on board the Terra and Aqua satellites provide horizontal and temporal variations of aerosol optical depth, while the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) offers the altitudes of aerosol-layers. The combined ground-based and satellite measurements indicated several interesting features among which were the large differences in the aerosol properties observed in July and February. We applied the climatology of aerosol properties for designing the Two-Column Aerosol Project (TCAP), which is supported by the U.S. Department of Energy’s (DOE’s) Atmospheric Radiation Measurement (ARM) Program. The TCAP field campaign involves 12-month deployment (started July 1, 2012) of the ground-based ARM Mobile Facility (AMF) and Mobile Aerosol Observing System (MAOS) on Cape Cod and complimentary aerosol observations from two research aircraft: the DOE Gulfstream-1 (G-1) and the National Aeronautics and Space Administration (NASA) B200 King Air. Using results from the coordinated G-1 and B200 flights during the recent (July, 2012) Intensive Observation Period, we demonstrated that the G-1 in situ measurements and B200 active remote sensing can provide complementary information on the temporal and spatial changes of the aerosol properties off the coast of North America.

  18. Aerosol properties in Titan's upper atmosphere from UVIS airglow observations

    NASA Astrophysics Data System (ADS)

    Lavvas, Panayotis; Koskinen, Tommi; Royer, Emilie; Rannou, Pascal; West, Robert A.

    2015-11-01

    Multiple Cassini observations reveal that the abundant aerosol particles in Titan's atmosphere are formed at high altitudes, particularly in the thermosphere [1]. They subsequently fall towards the lower atmosphere, and in their path, their size, shape, and population change in reflection to the variable atmospheric conditions.Although multiple observations can help us retrieve information for the aerosol properties in the lower atmosphere [2], we have limited knowledge for their properties in the altitude range between their formation region in the thermosphere, and the upper region of the main haze layer. UVIS is one of a few instruments that can probe this part of the atmosphere and allow for the retrieval of the aerosol properties.Here we analyze observations of atmospheric airglow that demonstrate the signature of N2 emissions and light scattering from aerosol particles, at different altitudes above 500 km [3]. We fit these observations with a combined model of N2 airglow [4] and atmospheric scattering by gases and aerosols that allows us to separate the pure scattering component and retrieve the aerosol size (distribution) and density. We particularly focus on observations from the T32 flyby that probed high southern latitudes in 2007 and combine good altitude resolution with high signal to noise ratio. We combine these with observations at different phase angles and observing geometry conditions (nadir vs. limb) in order to set better constraints on the aerosol properties.Our preliminary results demonstrate an increase in the average particle size with decreasing altitude in the atmosphere, from about 10 nm at 800 km to ~50 nm at 500 km, and an extinction profile at 185 nm wavelength, similar to the profile derive from UVIS occultation measurements at lower latitudes [5].[1] Lavvas et al. 2013. PNAS, doi/10.1073/pnas.1217059110, and references therein.[2] Tomasko et al. 2008, PSS, 56, p.669; Bellucci et al. 2009, Icarus 201, p.198[3] Ajello et al. 2008, GRL

  19. Heterogeneous Reactions in Atmospheric Aerosols Observed Using ATOFMS

    NASA Astrophysics Data System (ADS)

    Ryan, Sullivan

    2005-03-01

    The heterogeneous aging of natural atmospheric particles by reactive gases in the troposphere has been investigated in a flow-tube reactor using Aerosol Time-of-Flight Mass Spectrometry (ATOFMS) to monitor changes in the particle composition in real-time. Sea- salt and mineral dust aerosols were introduced into the flow tube simultaneously and reacted with nitric acid in a relative rate experiment. ATOFMS is a single-particle technique and thus enables us to distinguish which particle type accumulates more nitric acid. This allows us to determine if the differing surface area or kinetics is driving the partitioning of nitric acid between the sea salt and dust. The results of these and other aerosol flow-tube kinetics experiments will be presented. The atmospheric implications will be emphasized, particularly in relation to observations made by ATOFMS of heterogeneous reactions occurring in particles over the Pacific Ocean during ACE-Asia.

  20. TES Limb-Geometry Observations of Aerosols

    NASA Technical Reports Server (NTRS)

    Smith, Michael D.

    2003-01-01

    The Thermal Emission Spectrometer (TES) on-board Mars Global Surveyor (MGS) has a pointing mirror that allows observations in the plane of the orbit anywhere from directly nadir to far above either the forward or aft limbs for details about the TES instrument). Nadir-geometry observations are defined as those where the field-of-view contains the surface of Mars (even if the actual observation is at a high emission angle far from true nadir). Limb-geometry observations are defined as those where the line-of-sight of the observations does not intersect the surface. At a number of points along the MGS orbit (typically every 10 deg. or 20 deg. of latitude) a limb sequence is taken, which includes a stack of overlapping TES spectra from just below the limb to more than 120 km above the limb. A typical limb sequence has approx. 20 individual spectra, and the projected size of a TES pixel at the limb is 13 km.

  1. Quantifying Aerosol Direct Effects from Broadband Irradiance and Spectral Aerosol Optical Depth Observations

    SciTech Connect

    Creekmore, Torreon N.; Joseph, Everette; Long, Charles N.; Li, Siwei

    2014-05-16

    We outline a methodology using broadband and spectral irradiances to quantify aerosol direct effects on the surface diffuse shortwave (SW) irradiance. Best Estimate Flux data span a 13 year timeframe at the Department of Energy Atmospheric Radiation Measurement Program’s Southern Great Plains (SGP) site. Screened clear-sky irradiances and aerosol optical depth (AOD), for solar zenith angles ≤ 65°, are used to estimate clear-sky diffuse irradiances. We validate against detected clear-sky observations from SGP’s Basic Radiation System (BRS). BRS diffuse irradiances were in accordance with estimates, producing a root-mean-square error and mean bias errors of 4.0 W/m2 and -1.4 W/m2, respectively. Absolute differences show 99% of estimates within ±10 W/m2 (10%) of the mean BRS observations. Clear-sky diffuse estimates are used to derive quantitative estimates of aerosol radiative effects, represented as the aerosol diffuse irradiance (ADI). ADI is the contribution of diffuse SW to global SW, attributable to scattering of atmospheric transmission by natural plus anthropogenic aerosols. Estimated slope for the ADI as a function of AOD indicates an increase of ~22 W/m2 in diffuse SW for every 0.1 increase in AOD. Such significant increases in the diffuse fraction could possibly increase photosynthesis. Annual mean ADI is 28.2 W/m2, and heavy aerosol loading at SGP provides up to a maximum increase of 120 W/m2 in diffuse SW over background conditions. With regard to seasonal variation, the mean diffuse forcings are 17.2, 33.3, 39.0, and 23.6 W/m2 for winter, spring, summer, and fall, respectively.

  2. Measurements of Intensive Aerosol Optical Properties During TexAQS II

    NASA Astrophysics Data System (ADS)

    Atkinson, D. B.; Radney, J. G.; Wright, M. E.

    2007-12-01

    Time-resolved measurements of the bulk extensive aerosol optical properties - particle extinction coefficient (bext) and particle scattering coefficient (bscat) - and particle number concentrations were made as part of the six-week TRAMP experiment during the TexAQS II (2006) study. These measurements were done at a nominal surface site (the roof of an 18 story building) on the University of Houston campus near downtown Houston, Texas. Our ground-based tandem cavity ring-down transmissometer/nephelometer instrument (CRDT/N) provided the aerosol optical property measurements. A commercial Condensation Particle Counter (TSI 3007) was used to measure the number concentrations during part of the study period. The optical data was used to construct the intensive aerosol optical properties single scattering albedo ω0 at 532 nm and the Angstrom exponent for extinction between 532 nm and 1064 nm. Recent validation studies of size- selected laboratory generated aerosols are presented to illustrate the soundness of this approach using our instrument. The Angstrom exponent is compared to values from other instruments operating in the area and is found to be a characteristic of the regional air mass under some conditions. Size distributions measured during the study were used to create a new empirical adjustment to scattering measured by the Radiance Research nephelometer, resulting in improved results for particle absorption coefficient and single scattering albedo. The study average value of ω0(532 nm) = 0.78 is lower than expected from comparable field studies and even lower values are experienced during the study. Possible causes of this discrepancy are examined and the utility of using the current version of the CRDT/N instrument to measure the key radiative property ω0 is assessed. Observed episodes of rapid increases in particle number concentration with little corresponding growth in the optical properties can presumably be used to signal the occurrence of particle

  3. Investigation of aerosol optical properties for remote sensing through DRAGON (distributed regional aerosol gridded observation networks) campaign in Korea

    NASA Astrophysics Data System (ADS)

    Lim, Jae-Hyun; Ahn, Joon Young; Park, Jin-Soo; Hong, You-Deok; Han, Jin-Seok; Kim, Jhoon; Kim, Sang-Woo

    2014-11-01

    Aerosols in the atmosphere, including dust and pollutants, scatters/absorbs solar radiation and change the microphysics of clouds, thus influencing the Earth's energy budget, climate, air quality, visibility, agriculture and water circulation. Pollutants have also been reported to threaten the human health. The present research collaborated with the U.S. NASA and the U.S. Aerosol Robotic Network (AERONET) is to study the aerosol characteristics in East Asia and improve the long-distance transportation monitoring technology by analyzing the observations of aerosol characteristics in East Asia during Distributed Regional Aerosol Gridded Observation Networks (DRAGON) Campaign (March 2012-May 2012). The sun photometers that measure the aerosol optical characteristics were placed evenly throughout the Korean Peninsula and concentrated in Seoul and the metropolitan area. Observation data are obtained from the DRAGON campaign and the first year (2012) observation data (aerosol optical depth and aerosol spatial distribution) are analyzed. Sun photometer observations, including aerosol optical depth (AOD), are utilized to validate satellite observations from Geostationary Ocean Color Imager (GOCI) and Moderate Resolution Imaging Spectroradiometer (MODIS). Additional analysis is performed associated with the Northeast Asia, the Korean Peninsula in particular, to determine the spatial distribution of the aerosol.

  4. Organic aerosol mixing observed by single-particle mass spectrometry.

    PubMed

    Robinson, Ellis Shipley; Saleh, Rawad; Donahue, Neil M

    2013-12-27

    We present direct measurements of mixing between separately prepared organic aerosol populations in a smog chamber using single-particle mass spectra from the high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS). Docosane and docosane-d46 (22 carbon linear solid alkane) did not show any signs of mixing, but squalane and squalane-d62 (30 carbon branched liquid alkane) mixed on the time scale expected from a condensational-mixing model. Docosane and docosane-d46 were driven to mix when the chamber temperature was elevated above the melting point for docosane. Docosane vapors were shown to mix into squalane-d62, but not the other way around. These results are consistent with low diffusivity in the solid phase of docosane particles. We performed mixing experiments on secondary organic aerosol (SOA) surrogate systems finding that SOA derived from toluene-d8 (a surrogate for anthropogenic SOA (aSOA)) does not mix into squalane (a surrogate for hydrophobic primary organic aerosol (POA)) but does mix into SOA derived from α-pinene (biogenic SOA (bSOA) surrogate). For the aSOA/POA, the volatility of either aerosol does not limit gas-phase diffusion, indicating that the two particle populations do not mix simply because they are immiscible. In the aSOA/bSOA system, the presence of toluene-d8-derived SOA molecules in the α-pinene-derived SOA provides evidence that the diffusion coefficient in α-pinene-derived SOA is high enough for mixing on the time scale of 1 min. The observations from all of these mixing experiments are generally invisible to bulk aerosol composition measurements but are made possible with single-particle composition data. PMID:24131283

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

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

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

  6. CRISM Limb Observations of Aerosols and Water Vapor

    NASA Technical Reports Server (NTRS)

    Smith, Michael D.; Wolff, M.J.; Clancy, R.T.; Seelos, F.; Murchie, S.L.

    2009-01-01

    Near-infrared spectra taken in a limb-viewing geometry by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) on-board the Mars Reconnaissance Orbiter (MRO) provide a useful tool for probing atmospheric structure. Here we describe preliminary work on the retrieval of vertical profiles of aerosols and water vapor from the CRISM limb observations. The first full set of CRISM limb observations was taken in July 2009, with subsequent limb observations planned once every two months. Each set of limb observations contains about four dozen scans across the limb giving pole-to-pole coverage for two orbits at roughly 100 and 290 W longitude. Radiative transfer modeling taking account of aerosol scattering in the limb-viewing geometry is used to model the observations. The retrievals show the height to which dust and water vapor extend and the location and height of water ice clouds. Results from the First set of CRISM limb observations (July 2009, Ls=300) show dust aerosol well-mixed to about three scale heights above the surface with thin water ice clouds above the dust near the equator and at mid-northern latitudes. Water vapor is concentrated at high southern latitudes.

  7. Aerosol accumulation intensity and composition variations under different weather conditions in urban environment

    NASA Astrophysics Data System (ADS)

    Steinberga, Iveta; Bikshe, Janis; Eindorfa, Aiva

    2014-05-01

    During the last decade aerosol (PM10, PM2.5) mass and composition measurements were done in different urban environments - parallel street canyons, industrial sites and at the background level in Riga, Latvia. Effect of meteorological parameters on the accumulation and ventilation intensity was investigated in order to understand microclimatological parameters affecting aerosol pollution level and chemical composition changes. In comparison to industrial sites (shipping activities, bulk cargo, oil and naphtha processing), urban street canyon aerosol mass concentration was significantly higher, for PM10 number of daily limit exceedances are higher by factor 3.4 - 3.9 in street canyons. Exceedances of PM2.5 annual limits were identified only in street canyons as well. Precipitation intensity, wind speed, days with mist highly correlates with aerosol concentration; in average during the year about 1 - 2 % presence of calm wind days, 20 - 30 days with mist facilitate accumulation of aerosols and mitigating growing of secondary aerosols. It has been assessed that about 25 % of daily exceedances in street canyons are connected with sea salt/street sanding factor. Strong dependency of wind speed and direction were identified in winter time - low winds (0.4 - 1.7 m/s) blowing from south, south-east (cross section of the street) contributing to PM10 concentrations over 100 - 150 ug/m3. Seasonal differences in aerosol concentrations were identified as a result of recombination of direct source impact, specific meteorological and synoptical conditions during the period from January until April when usually dominates extremely high aerosol concentrations. While aerosol mass concentration levels in monitoring sites significantly differs, concentrations of heavy metals (Pb, Ni, Cd, and As) are almost at the same level, even more - concentration of Cd for some years was higher in industrial area where main pollution is caused by oil processing and storage, heavy traffic

  8. Where on Earth can we observe pristine aerosol?

    NASA Astrophysics Data System (ADS)

    Hamilton, Douglas; Carslaw, Ken; Spracklen, Dominick; Lee, Lindsay; Pringle, Kirsty; Reddington, Carly

    2014-05-01

    To understand how sensitive the climate is to greenhouse gas and aerosol emissions it is important to define the baseline from which the aerosol forcings are calculated [Carslaw et al., 2013]; but if no regions in the world are anthropogenically unaltered, where on Earth can we observe and learn about the behaviour of pristine environments? This question is relevant to both future modelling and long-term observational studies in climate science. Identification of such regions is also important if we are to fully understand climate response to natural aerosol changes [Spracklen and Rap, 2013]. Here we use a combination of model simulations and statistical emulation of the Global Model of Aerosol Processes (GLOMAP) to identify regions which are most pristine in today's atmosphere. The simulations are used to identify present day (PD) regions which have daily mean cloud condensation nuclei (CCN) concentration similar to pre-industrial (PI) levels. The emulation of an ensemble of perturbed parameter runs [Lee et al., 2013] for the PI and PD allows a full Monte Carlo variance-based sensitivity analysis of CCN to 28 different parameters, covering both natural and anthropogenic emissions and their processes, which affect the uncertainty in CCN concentrations. We use this information to assess which regions exhibit little change in the sensitivity the 28 parameters between the PI and PD. Potentially pristine environments are defined based on where both the CCN number concentration and its sensitivity to the 28 parameters have remained constant through the industrial period. Our results indicate that the low to mid-latitude maritime southern hemisphere is the most pristine region in the PD atmosphere, especially during the austral summer. Other pristine regions include Alaska and Yukon, the Melanesian islands and the Antarctic Peninsula. Simulated anthropogenic influence on CCN has high seasonality in the southern hemisphere but low seasonality in the northern hemisphere

  9. Rural continental aerosol properties and processes observed during the Hohenpeissenberg Aerosol Characterization Experiment (HAZE2002)

    NASA Astrophysics Data System (ADS)

    Hock, N.; Schneider, J.; Borrmann, S.; Römpp, A.; Moortgat, G.; Franze, T.; Schauer, C.; Pöschl, U.; Plass-Dülmer, C.; Berresheim, H.

    2007-06-01

    particles. The average ratio of OM1 to OC2.5 was 2, indicating a high proportion of heteroelements in the organic fraction of the sampled rural aerosol. This is consistent with the high ratio of oxygenated organic aerosol (OOA) over hydrocarbon-like organic aerosol (HOA) inferred from the AMS results (4:1), and also with the high abundance of proteins (~3%) indicating a high proportion of primary biological material (~30%) in PM2.5. Moreover, the low abundance of PAHs (<1 ng m-3) and EC (<1 μg m-3) in PM2.5 confirm a low contribution of combustion emissions, which are usually also major sources for HOA. Slightly enhanced HOA concentrations indicating fresh anthropogenic emissions were observed during a period when air masses were advected from the densely populated Po Valley, Italy. Detection of several secondary organic aerosol compounds (dicarboxylic acids) and their precursors (monoterpenes) confirmed the finding that secondary aerosol from natural sources was an important aerosol constituent. A sharp decrease of the short lived monoterpenes indicated that during night-time the measurement station was isolated from ground emission sources by a stable inversion layer. Nighttime values can therefore be regarded to represent regional or long range transport. New particle formation was observed almost every day with particle number concentrations exceeding 104 cm-3 (nighttime background level 1000-2000 cm-3). Closer inspection of two major events indicated that ternary H2SO4/H2O/NH3 nucleation triggered particle formation and that condensation of both organic and inorganic species contributed to particle growth.

  10. Radiation and temperature effects of the intensive injection of dust aerosol into the atmosphere

    NASA Astrophysics Data System (ADS)

    Gorchakova, I. A.; Mokhov, I. I.; Rublev, A. N.

    2015-03-01

    Based on the measurements at the AERONET station (Ilorin, Nigeria), quantitative estimates of radiation and temperature effects of dust aerosol during the intensive sand storm in the Sahara Desert from January 28 to February 6, 2000, are obtained. The model used in calculations implies particles of dust aerosol being no more than 15 μm in radius (according to the data from AERONET station); another model takes into account large particles (LPs) up to 60 μm in radius and involves a spectral variation in the OPAC refraction index. In the short infrared region, the optical thickness of aerosol weakening increases with LPs taken into account in the aerosol model; the albedo of aerosol single scattering reduces in comparison to the respective optical parameters of the first model. Dust aerosol cools the earth's surface. In the presence of LPs in dust aerosol, the surface-atmosphere system can both cool and warm, while if LPs less than 15 μm in size are not taken into account, the surface cools. The rate of cooling of the 10-m near-surface atmospheric layer Δ T/Δ t changes in the interval of -(4-21)°C/day without the influence of LPs over 15 μm in size on solar radiation transfer taken into account; if this influence is taken into account, the rate is -(6-36)°C/day. In the long infrared region, the surface-atmosphere system warms more intensively if LPs are taken into account by the aerosol model. The heating rate of the 10-m near-surface atmospheric layer does not exceed ~0.5°C/day during the entire period of dust emission without LPs taken into account (AERONET algorithm); if LPs are taken into account (modeling results), heating rate reaches a maximal value of ~0.6°C/day.

  11. First observational Evidence of Rossby Wave Signatures in Spectral Aerosol Optical Depths over Central Himalayas

    NASA Astrophysics Data System (ADS)

    Devulapalli, P. V.; Kondapalli, N. K.; Krishna, S.; Ratnam, M.; Naja, M. K.; Kishore, R.

    2013-12-01

    It is now well known that the atmospheric aerosols (both natural and anthropogenic) exhibit large spatial, temporal and spectral uncertainties due to the short residence time and the diverse aerosol types. For example, aerosol loading varies not only from year to year but also on higher frequency intra-seasonal time scales producing strong variability on local and regional scales. Considering the advancements in the morphology of aerosol layers and their contribution to earth's radiation budget, recent studies tried to understand the role of atmospheric waves in variability of AODs from fast moving gravity waves to slow moving planetary-scale waves. It is also evident from earlier reports that the planetary-scale waves are intense in winter in both the hemispheres and play vital role in transporting not only energy and momentum but also atmospheric trace species. Very few reports till date showed modulations in the spectral AODs, from the equatorial and tropical latitudes by Madden Julian Oscillation (MJO) which dominates the tropical variability on time scales of 30-70 days. However, there are no reports yet neither from mid- nor from high latitudes showing the effect of planetary scale waves on spectral AODs and their quantification of the aerosol radiative forcing due to long period modulations. Hence, it is very important to understand the variability of aerosols, and the spectral AODs in terms of atmospheric wave modulations. This could be an essential input to the global and regional aerosol models to assess the global and regional radiative forcing and subsequent climate impacts. For the first time, long period modulations in spectral Aerosol Optical Depths (AODs) over extra-tropical region, Manora Peak, Nainital (29.4oN; 79.2oE; 1957m AMSL) in Central Himalayas are presented. Power spectrum analysis of AODs showed the existence of dominant 25-45 day oscillation, apart from quasi-6.5 and quasi-16 day waves. The 25-45 day oscillations are also seen in MODIS

  12. [Ultraviolet Mie lidar observations of aerosol extinction in a dust storm case over Macao].

    PubMed

    Liu, Qiao-jun; Cheng, A Y S; Zhu, Jian-hua; Fong, S K; Chang, S W; Tam, K S; Viseu, A

    2012-03-01

    Atmospheric aerosol over Macao was monitored by using a 355 nm Mie scattering lidar during the dust event on March 22nd, 2010. Vertical profiles of aerosol extinction coefficients were obtained and correlated with local PM10 concentration. The near-surface aerosol extinction coefficients have good agreement with PM10 concentration values. The aerosol extinction vertical profiles showed that there were distinct layers of dust aerosol concentration. The source and tracks of dust aerosol were analyzed by back-trajectory simulation. Observations showed that this lidar could run well even in dust storm episode, and it would help to further the study on aerosol properties over Macao. PMID:22582620

  13. Rural continental aerosol properties and processes observed during the Hohenpeissenberg Aerosol Characterization Experiment (HAZE2002)

    NASA Astrophysics Data System (ADS)

    Hock, N.; Schneider, J.; Borrmann, S.; Römpp, A.; Moortgat, G.; Franze, T.; Schauer, C.; Pöschl, U.; Plass-Dülmer, C.; Berresheim, H.

    2008-02-01

    Detailed investigations of the chemical and microphysical properties of rural continental aerosols were performed during the HAZE2002 experiment, which was conducted in May 2002 at the Meteorological Observatory Hohenpeissenberg (DWD) in Southern Germany. Online measurements included: Size-resolved chemical composition of submicron particles; total particle number concentrations and size distributions over the diameter range of 3 nm to 9 μm; gas-phase concentration of monoterpenes, CO, O3, OH, and H2SO4. Filter sampling and offline analytical techniques were used to determine: Fine particle mass (PM2.5), organic, elemental and total carbon in PM2.5 (OC2.5, EC2.5, TC2.5), and selected organic compounds (dicarboxylic acids, polycyclic aromatic hydrocarbons, proteins). Overall, the non-refractory components of submicron particles detected by aerosol mass spectrometry (PM1, 6.6±5.4 μg m-3, arithmetic mean and standard deviation) accounted for ~62% of PM2.5 determined by filter gravimetry (10.6±4.7 μg m-3). The relative proportions of non-refractory submicron particle components were: (23±39)% ammonium nitrate, (27±23)% ammonium sulfate, and (50±40)% organics (OM1). OM1 was closely correlated with PM1 (r2=0.9) indicating a near-constant ratio of non-refractory organics and inorganics. The average ratio of OM1 to OC2.5 was 2.1±1.4, indicating a high proportion of heteroelements in the organic fraction of the sampled rural aerosol. This is consistent with the high ratio of oxygenated organic aerosol (OOA) over hydrocarbon-like organic aerosol (HOA) inferred from the AMS results (4:1), and also with the high abundance of proteins (~3%) indicating a high proportion of primary biological material (~30%) in PM2.5. This finding was confirmed by low abundance of PAHs (<1 ng m-3) and EC (<1 μg m-3) in PM2.5 and detection of several secondary organic aerosol compounds (dicarboxylic acids) and their precursors (monoterpenes). New particle formation was observed almost

  14. Observation of hydration of single, modified carbon aerosols

    NASA Technical Reports Server (NTRS)

    Wyslouzil, B. E.; Carleton, K. L.; Sonnenfroh, D. M.; Rawlins, W. T.; Arnold, S.

    1994-01-01

    We have compared the hydration behavior of single carbon particles that have been treated by exposure to gaseous H2SO4 with that of untreated particles. Untreated carbon particles did not hydrate as the relative humidity varied from 0 to 80% at 23 C. In contrast, treated particles hydrated under subsaturation conditions; mass increases of up to 30% were observed. The mass increase is consistent with sulfuric acid equilibration with the ambient relative humidity in the presence of inert carbon. For the samples studied, the average amount of absorbed acid was 14% +/- 6% by weight, which corresponds to a surface coverage of approximately 0.1 monolayer. The mass fraction of surface-absorbed acid is comparable to the soluble mass fraction observed by Whitefield et al. (1993) in jet aircraft engine aerosols. Estimates indicate this mass fraction corresponds to 0.1% of the available SO2 exiting an aircraft engine ending up as H2SO4 on the carbon aerosol. If this heterogeneous process occurs early enough in the exhaust plume, it may compete with homogeneous nucleation as a mechanism for producing sulfuric acid rich aerosols.

  15. Observation of hydration of single, modified carbon aerosols

    NASA Astrophysics Data System (ADS)

    Wyslouzil, B. E.; Carleton, K. L.; Sonnenfroh, D. M.; Rawlins, W. T.; Arnold, S.

    1994-09-01

    We have compared the hydration behavior of single carbon particles that have been treated by exposure to gaseous H2SO4 with that of untreated particles. Untreated carbon particles did not hydrate as the relative humidity varied from 0 to 80% at 23°C. In contrast, treated particles hydrated under subsaturation conditions; mass increases of up to 30% were observed. The mass increase is consistent with sulfuric acid equilibration with the ambient relative humidity in the presence of inert carbon. For the samples studied, the average amount of adsorbed acid was 14% ± 6% by weight, which corresponds to a surface coverage of ˜0.1 monolayer. The mass fraction of surface-adsorbed acid is comparable to the soluble mass fraction observed by Whitefield et al. (1993) in jet aircraft engine aerosols. Estimates indicate this mass fraction corresponds to 0.1% of the available SO2 exiting an aircraft engine ending up as H2SO4 on the carbon aerosol. If this heterogeneous process occurs early enough in the exhaust plume, it may compete with homogeneous nucleation as a mechanism for producing sulfuric acid rich aerosols.

  16. Observations of the first aerosol indirect effect in shallow cumuli

    SciTech Connect

    Berg, Larry K.; Berkowitz, Carl M.; Barnard, James C.; Senum, Gunar; Springston, Stephen R.

    2011-02-08

    Data from the Cumulus Humilis Aerosol Processing Study (CHAPS) are used to estimate the impact of both aerosol indirect effects and cloud dynamics on the microphysical and optical properties of shallow cumuli observed in the vicinity of Oklahoma City, Oklahoma. Not surprisingly, we find that the amount of light scattered by the clouds is dominated by their liquid water content (LWC), which in turn is driven by cloud dynamics. However, removing the effect of cloud dynamics by examining the scattering normalized by LWC shows a strong sensitivity of scattering to pollutant loading. These results suggest that even moderately sized cities, like Oklahoma City, can have a measureable impact on the optical properties of shallow cumuli.

  17. Scattering of intense femtosecond laser radiation at water aerosol in backward direction

    NASA Astrophysics Data System (ADS)

    Efimenko, E. S.; Malkov, Yu. A.; Murzanev, A. A.; Stepanov, A. N.

    2015-12-01

    We investigated the scattering of femtosecond laser pulses with intensities within the 1012-1013W/cm2 range at a water aerosol jet at 20° to backward direction. The scattered energy and spectra transformation as a function of incident intensity obtained in experiment show good agreement with the results of extensive numerical modeling based on self-consistent solution of Maxwell equations using a nonlinear 3D FDTD code and balance equation for plasma density.

  18. Aerosols, clouds, and precipitation in the North Atlantic trades observed during the Barbados aerosol cloud experiment - Part 1: Distributions and variability

    NASA Astrophysics Data System (ADS)

    Jung, Eunsil; Albrecht, Bruce A.; Feingold, Graham; Jonsson, Haflidi H.; Chuang, Patrick; Donaher, Shaunna L.

    2016-07-01

    Shallow marine cumulus clouds are by far the most frequently observed cloud type over the Earth's oceans; but they are poorly understood and have not been investigated as extensively as stratocumulus clouds. This study describes and discusses the properties and variations of aerosol, cloud, and precipitation associated with shallow marine cumulus clouds observed in the North Atlantic trades during a field campaign (Barbados Aerosol Cloud Experiment- BACEX, March-April 2010), which took place off Barbados where African dust periodically affects the region. The principal observing platform was the Center for Interdisciplinary Remotely Piloted Aircraft Studies (CIRPAS) Twin Otter (TO) research aircraft, which was equipped with standard meteorological instruments, a zenith pointing cloud radar and probes that measured aerosol, cloud, and precipitation characteristics.The temporal variation and vertical distribution of aerosols observed from the 15 flights, which included the most intense African dust event during all of 2010 in Barbados, showed a wide range of aerosol conditions. During dusty periods, aerosol concentrations increased substantially in the size range between 0.5 and 10 µm (diameter), particles that are large enough to be effective giant cloud condensation nuclei (CCN). The 10-day back trajectories showed three distinct air masses with distinct vertical structures associated with air masses originating in the Atlantic (typical maritime air mass with relatively low aerosol concentrations in the marine boundary layer), Africa (Saharan air layer), and mid-latitudes (continental pollution plumes). Despite the large differences in the total mass loading and the origin of the aerosols, the overall shapes of the aerosol particle size distributions were consistent, with the exception of the transition period.The TO was able to sample many clouds at various phases of growth. Maximum cloud depth observed was less than ˜ 3 km, while most clouds were less than 1 km

  19. Global observations of aerosol-cloud-precipitation-climate interactions

    NASA Astrophysics Data System (ADS)

    Rosenfeld, Daniel; Andreae, Meinrat O.; Asmi, Ari; Chin, Mian; Leeuw, Gerrit; Donovan, David P.; Kahn, Ralph; Kinne, Stefan; Kivekäs, Niku; Kulmala, Markku; Lau, William; Schmidt, K. Sebastian; Suni, Tanja; Wagner, Thomas; Wild, Martin; Quaas, Johannes

    2014-12-01

    Cloud drop condensation nuclei (CCN) and ice nuclei (IN) particles determine to a large extent cloud microstructure and, consequently, cloud albedo and the dynamic response of clouds to aerosol-induced changes to precipitation. This can modify the reflected solar radiation and the thermal radiation emitted to space. Measurements of tropospheric CCN and IN over large areas have not been possible and can be only roughly approximated from satellite-sensor-based estimates of optical properties of aerosols. Our lack of ability to measure both CCN and cloud updrafts precludes disentangling the effects of meteorology from those of aerosols and represents the largest component in our uncertainty in anthropogenic climate forcing. Ways to improve the retrieval accuracy include multiangle and multipolarimetric passive measurements of the optical signal and multispectral lidar polarimetric measurements. Indirect methods include proxies of trace gases, as retrieved by hyperspectral sensors. Perhaps the most promising emerging direction is retrieving the CCN properties by simultaneously retrieving convective cloud drop number concentrations and updraft speeds, which amounts to using clouds as natural CCN chambers. These satellite observations have to be constrained by in situ observations of aerosol-cloud-precipitation-climate (ACPC) interactions, which in turn constrain a hierarchy of model simulations of ACPC. Since the essence of a general circulation model is an accurate quantification of the energy and mass fluxes in all forms between the surface, atmosphere and outer space, a route to progress is proposed here in the form of a series of box flux closure experiments in the various climate regimes. A roadmap is provided for quantifying the ACPC interactions and thereby reducing the uncertainty in anthropogenic climate forcing.

  20. Ambient Observations of Organic Nitrogen Compounds in Submicrometer Aerosols in New York Using High Resolution Aerosol Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Zhou, S.; Ge, X.; Xu, J.; Sun, Y.; Zhang, Q.

    2015-12-01

    Organic nitrogen (ON) compounds, which include amines, nitriles, organic nitrates, amides, and N-containing aromatic heterocycles, are an important class of compounds ubiquitously detected in atmospheric particles and fog and cloud droplets. Previous studies indicate that these compounds can make up a significant fraction (20-80%) of the total nitrogen (N) content in atmospheric condensed phases and play important roles in new particle formation and growth and affecting the optical and hygroscopicity of aerosols. In this study, we report the observation of ON compounds in submicrometer particles (PM1) at two locations in New York based on measurements using Aerodyne high-resolution time-of-flight mass spectrometer (HR-ToF-AMS). One study was conducted as part of the US Department of Energy funded Aerosol Lifecyle - Intensive Operation Period (ALC-IOP) campaign at Brookhaven National Lab (BNL, 40.871˚N, 72.89˚W) in summer, 2011 and the other was conducted at the Queen's College (QC) in New York City (NYC) in summer, 2009. We observed a notable amount of N-containing organic fragment ions, CxHyNp+ and CxHyOzNp+, in the AMS spectra of organic aerosols at both locations and found that they were mainly associated with amino functional groups. Compared with results from lab experiments, the C3H8N+ at m/z = 58 was primarily attributed to trimethylamine. In addition, a significant amount of organonitrates was observed at BNL. Positive matrix factorization (PMF) analysis of the high resolution mass spectra (HRMS) of organic aerosols identified a unique nitrogen-enriched OA (NOA) factor with elevated nitrogen-to-carbon (N/C) at both BNL and QC. Analysis of the size distributions, volatility profiles, and correlations with external tracer indicates that acid-base reactions of amino compounds with sulfate and acidic gas were mainly responsible for the formation of amine salts. Photochemical production was also observed to play a role in the formation of NOA. Bivariate polar

  1. Aerosol observing system platform integration and AAF instrumentation

    SciTech Connect

    Springston, S.; Sedlacek, A.

    2010-03-15

    As part of the federal government’s 2009 American Recovery and Reinvestment Act (ARRA), the U.S. DOE Office of Science allocated funds for the capital upgrade of the Atmospheric Radiation Measurement (ARM) Climate Research Facility to improve and expand observational capabilities related to cloud and aerosol properties. The ARM Facility was established as a national user facility for the global scientific community to conduct a wide range of interdisciplinary science. Part of the ARRA-funded expansion of the ARM Facility includes four new Aerosol Observing Systems (AOS) to be designed, instrumented, and mentored by BNL. The enclosures will be customized SeaTainers. These new platforms ([AMF2]: ARM Mobile Facility-2; [TWP-D]: Tropical Western Pacific at Darwin; and [MAOS-A]/[MAOS-C]: Mobile Aerosol Observing System-Aerosol/-Chemistry) will provide a laboratory environment for fielding instruments to collect data on aerosol life cycle, microphysics, and optical/physical properties. The extensive instrument suite includes both established methods and initial deployments of new techniques to add breadth and depth to the AOS data sets. The platforms are designed: (1) to have all instruments pre-installed before deployment, allowing a higher measurement duty cycle; (2) with a standardized configuration improving the robustness of data inter-comparability; (3) to provide remote access capability for instrument mentors; and (4) to readily accommodate guest instrumentation. The first deployment of the AMF2 platform will be at the upcoming StormVEx campaign held at Steamboat Springs, Colorado, October 15, 2010–March 31, 2011 while the TWP-D AOS will be stationed at the ARM Darwin site. The maiden deployments of the MAOS-A and MAOS-C platforms will be during the Ganges Valley Experiment (GVAX) scheduled for April 2011–April 2012. In addition to the ground-based AOS platforms, thee major instrument builds for the AAF are also being undertaken (new trace gas package [NO

  2. Martian upper atmospheric aerosol properties from Phobos eclipse observation

    NASA Astrophysics Data System (ADS)

    Lemmon, Mark T.

    2015-11-01

    Solar occultation photometry is a useful method for probing upper atmospheric aerosols, using a long atmospheric path for direct extinction measurements. During April-June 2015, the Mars Science Laboratory’s Mastcam was used for solar occultation photometry by proxy: 3 eclipse ingresses by Phobos into Mars’ shadow were observed, as were 3 egresses from the shadow. The observations occurred in late Southern summer, at LS 331-352°. The observations of the moon’s brightness sample the Martian atmosphere along the lines of site from the Sun to Phobos. The ingresses and egresses sampled longitudes up to 1000s of km west or east of the rover’s position, respectively; sampled latitudes from 30° S to 7° S over time; and sampled local sunset or sunrise, respectively. Each eclipse was imaged with both Mastcam cameras, M-100 with an RGB filter (638, 551, and 493 nm) and M-34 with an 867-nm filter. Light-curves for the eclipses were derived from the images and interpreted via a geometric model of the event, accounting for the full range of lines of sight through the atmosphere. The altitude of 50% extinction was found to vary within the 40-60 km range. Extinction varied with wavelength: four events showed significantly higher extinction in the blue, with a monotonic decrease with wavelength, interpreted as a result of 0.3-0.4 μm dust aerosols. Two events (one of each type) showed no significant wavelength variation of extinction, interpreted as a result of large (>1 μm) aerosols. One of these, probing local sunrise conditions, may suggest a thin layer of CO2 ice cloud. Future work may allow retrieval of vertical gradients in aerosol size near the mid-point of the sensitive region (i.e., altitudes near that of 50% transmission and/or path optical depth unity) and/or identification of discrete layers vs. well-mixed aerosols (for instance, clouds vs. dust)

  3. MISR Satellite Observations of Aerosol Types Affecting Human Health

    NASA Astrophysics Data System (ADS)

    Kalashnikova, O. V.; Franklin, M.; Garay, M. J.; Diner, D. J.

    2015-12-01

    Ground-based observations of pollutants and concentrations of particulate matter (PM), that includes small particles designated PM2.5 and dust-dominated PM10, are the gold standard in studies of environmental impacts on human health. However, because monitoring stations are costly, they typically provide only limited spatial coverage, especially in rural and remote areas. We will demonstrate how data from the Multi-angle Imaging SpectroRadiometer (MISR) instrument that has been flying on NASA's Terra Earth Observing System satellite since early 2000 can be used to provide estimates of surface PM types. The current MISR operational aerosol retrieval uses a combination of multi-spectral and multi-angle data to retrieve aerosol optical depth (AOD) and particle property information (including dust AOD) globally at 17.6 km spatial resolution. Using the same algorithm with data collected in all 36-channels at 275 m resolution (Local Mode), which is available over greater Los Angeles area, and also was activated during 2013 DISCOVER-AQ California field campaign, high-resolution 4.4 km aerosol retrievals were performed in addition to the standard 17.6 km retrievals. The 4.4 km spatial resolution of the PM information data is fine enough to be able to resolve local differences in PM loading that may be important for understanding regional health effects of pollution in the region. In particular, we demonstrate that MISR high-resolution AOD retrievals are in better agreement with ground-based aerosol observations and reveal more details about the aerosol spatial variability compared to the MISR standard 17.6 km product. Then we will discuss techniques and show examples of the application of high-resolution MISR data to provide estimates of surface PM for the greater Los Angeles area in 2008 and for California San Joaquin Valley during the 2013 DISCOVER-AQ field campaign. Finally, we will discuss future NASA instruments that will provide new information allowing for better

  4. New Directions: Emerging Satellite Observations of Above-cloud Aerosols and Direct Radiative Forcing

    NASA Technical Reports Server (NTRS)

    Yu, Hongbin; Zhang, Zhibo

    2013-01-01

    Spaceborne lidar and passive sensors with multi-wavelength and polarization capabilities onboard the A-Train provide unprecedented opportunities of observing above-cloud aerosols and direct radiative forcing. Significant progress has been made in recent years in exploring these new aerosol remote sensing capabilities and generating unique datasets. The emerging observations will advance the understanding of aerosol climate forcing.

  5. Influence of Observed Diurnal Cycles of Aerosol Optical Depth on Aerosol Direct Radiative Effect

    NASA Technical Reports Server (NTRS)

    Arola, A.; Eck, T. F.; Huttunen, J.; Lehtinen, K. E. J.; Lindfors, A. V.; Myhre, G.; Smirinov, A.; Tripathi, S. N.; Yu, H.

    2013-01-01

    The diurnal variability of aerosol optical depth (AOD) can be significant, depending on location and dominant aerosol type. However, these diurnal cycles have rarely been taken into account in measurement-based estimates of aerosol direct radiative forcing (ADRF) or aerosol direct radiative effect (ADRE). The objective of our study was to estimate the influence of diurnal aerosol variability at the top of the atmosphere ADRE estimates. By including all the possible AERONET sites, we wanted to assess the influence on global ADRE estimates. While focusing also in more detail on some selected sites of strongest impact, our goal was to also see the possible impact regionally.We calculated ADRE with different assumptions about the daily AOD variability: taking the observed daily AOD cycle into account and assuming diurnally constant AOD. Moreover, we estimated the corresponding differences in ADREs, if the single AOD value for the daily mean was taken from the the Moderate Resolution Imaging Spectroradiometer (MODIS) Terra or Aqua overpass times, instead of accounting for the true observed daily variability. The mean impact of diurnal AOD variability on 24 h ADRE estimates, averaged over all AERONET sites, was rather small and it was relatively small even for the cases when AOD was chosen to correspond to the Terra or Aqua overpass time. This was true on average over all AERONET sites, while clearly there can be much stronger impact in individual sites. Examples of some selected sites demonstrated that the strongest observed AOD variability (the strongest morning afternoon contrast) does not typically result in a significant impact on 24 h ADRE. In those cases, the morning and afternoon AOD patterns are opposite and thus the impact on 24 h ADRE, when integrated over all solar zenith angles, is reduced. The most significant effect on daily ADRE was induced by AOD cycles with either maximum or minimum AOD close to local noon. In these cases, the impact on 24 h ADRE was

  6. Lessons Learned About Organic Aerosol Formation in the Southeast U.S. Using Observations and Modeling

    EPA Science Inventory

    Isoprene emitted by vegetation is an important precursor of secondary organic aerosol (SOA). In this work, modeling of isoprene SOA via heterogeneous uptake is explored and compared to observations from the Southern Oxidant and Aerosol Study (SOAS).

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

    NASA Technical Reports Server (NTRS)

    Thomason, L. W.

    2012-01-01

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

  8. SOIR/VEX mesospheric aerosols observations and modelling

    NASA Astrophysics Data System (ADS)

    Wilquet, Valérie; Carine Vandaele, Ann; Drummond, Rachel; Mahieux, Arnaud; Robert, Séverine; Daerden, Frank; Neary, Lori; Bertaux, Jean-Loup

    2013-04-01

    SPICAV/SOIR on-board Venus Express is able to target the layer of aerosols above the cloud layer at the terminator (Wilquet et al., 2009). A high temporal variability in the aerosol content in Venus' atmosphere was inferred from SOIR observations, as well as a latitudinal dependency of the aerosol loading (Wilquet et al., 2012). This is in agreement with results from previous missions and with the facts that (i) H2SO4 aerosol particles are formed through SO2 photo-oxidation and hydration at the cloud top of Venus, (ii) SO2 photolysis is more efficient at low latitudes, (iii) the altitude of the cloud top is up to one scale height lower in the polar region than at the equator. A increasing SO2 abundance with increasing altitude was recently observed with SPICAV-UV at altitudes of ~ 85-105 km (Belyaev et al., 2012) but also from microwave ground-based spectra in the Venus mesosphere (Sandor et al., 2010), which suggest a source of SO2 at high altitudes. Zhang et al. (2012) proposed a one dimensional photochemistry-diffusion model in order to reconcile these puzzling findings; he suggested that H2SO4 might be a source of SO2 above 90 km through aerosol evaporation followed by SO3 photolysis. This model and the observations are however disputed by others demonstrating the necessity for a more global interpretation of the observations and for modelling of the upper haze layer. For example, the variations in aerosol loading can be compared to other key parameters of the atmosphere retrieved from the same SOIR spectra such as water and SO2 composition or temperature. In addition, a microphysical model is being developed that will calculate the time dependent haze particle size distributions assuming an initial size distribution of background sulphate aerosols. The model will simulate the formation, growth, evaporation, and sedimentation of particles. Results of this on-going research will be presented and discussed. References : Belyaev, D.A., F. Montmessin, J.-L. Bertaux

  9. Spatio-temporal representativeness of aerosol remote sensing observations

    NASA Astrophysics Data System (ADS)

    Schutgens, Nick; Gryspeerdt, Edward; Tsyro, Svetlana; Goto, Daisuke; Watson-Parris, Duncan; Weigum, Natalie; Schulz, Michael; Stier, Philip

    2016-04-01

    One characteristic of remote sensing observations is the strong intermittency with which they observe the same scene. Due to unfavourable conditions (due to e.g. low visible light, cloudiness or high surface albedo), sampling constraints (due to e.g. polar orbits) or instrument malfunction or maintenance, gaps in the observing record of hours to months exist. At the same time, satellite L3 products often are spatial aggregates over considerable distances (e.g. 1 by 1 degree). We study the impact of spatio-temporal sampling of observations on their representativeness: i.e. how well can satellite products represent the large scale (~ 100 by 100 km) aerosol field over periods of days, months, or years. This study was conducted by using diverse global and regional aerosol models as a truth and sub-sample them according to actual observations. In this way, we have been able to study the representativeness of different observing systems like MODIS, CALIOP and AERONET. Monthly and yearly averages allow serious sampling errors, that may still be present in multi-year climatologies due to recurring observing patterns. Even daily averages are affected as diurnal cycles can often not be observed. We discuss the implications these representativeness errors have for e.g. model evaluation or the construction of climatologies. We also assess similar representativeness issues in ground site in-situ observations from e.g. EMEP or IMPROVE and show that satellite datasets have distinct advantages due to their better spatial coverage provided temporal sampling is dealt with properly (i.e. through collocation of datasets). Finally, we briefly introduce a software tool (the Community Intercomparison Suite or CIS) that is designed to improve representativeness of datasets in intercomparion studies through aggregation and collocation of data.

  10. Sizing of individual aerosol particles using TAOS (Two-dimensional Angular Optical Scattering) pattern total intensity

    NASA Astrophysics Data System (ADS)

    Zallie, J. T.; Aptowicz, K. B.; Martin, S.; Pan, Y.

    2015-12-01

    The morphology of single aerosol particles has been explored previously using the TAOS (Two-dimensional Angular Optical Scattering) technique, which captures angularly resolved scattering patterns. Particle size is known to strongly influence the light scattering properties of aerosols and therefore is a critical parameter to discern from the TAOS patterns. In this work, T-matrix simulation of light scattering from spherical and spheroidal particles is used to explore the possibility of sizing particles from the total light scattering signal detected using the TAOS technique. Scattering patterns were calculated for particles that span various particle sizes, spheroidal shapes, complex refractive indices and particles orientations representative of atmospheric aerosol distributions. A power law relationship between particle size and total scattering intensity was found that could crudely size particles but with significant error.

  11. Synergic use of TOMS and Aeronet Observations for Characterization of Aerosol Absorption

    NASA Technical Reports Server (NTRS)

    Torres, O.; Bhartia, P. K.; Dubovik, O.; Holben, B.; Siniuk, A.

    2003-01-01

    The role of aerosol absorption on the radiative transfer balance of the earth-atmosphere system is one of the largest sources of uncertainty in the analysis of global climate change. Global measurements of aerosol single scattering albedo are, therefore, necessary to properly assess the radiative forcing effect of aerosols. Remote sensing of aerosol absorption is currently carried out using both ground (Aerosol Robotic Network) and space (Total Ozone Mapping Spectrometer) based observations. The satellite technique uses measurements of backscattered near ultraviolet radiation. Carbonaceous aerosols, resulting from the combustion of biomass, are one of the most predominant absorbing aerosol types in the atmosphere. In this presentation, TOMS and AERONET retrievals of single scattering albedo of carbonaceous aerosols, are compared for different environmental conditions: agriculture related biomass burning in South America and Africa and peat fires in Eastern Europe. The AERONET and TOMS derived aerosol absorption information are in good quantitative agreement. The most absorbing smoke is detected over the African Savanna. Aerosol absorption over the Brazilian rain forest is less absorbing. Absorption by aerosol particles resulting from peat fires in Eastern Europe is weaker than the absorption measured in Africa and South America. This analysis shows that the near UV satellite method of aerosol absorption characterization has the sensitivity to distinguish different levels of aerosol absorption. The analysis of the combined AERONET-TOMS observations shows a high degree of synergy between satellite and ground based observations.

  12. Improving National Air Quality Forecasts with Satellite Aerosol Observations.

    NASA Astrophysics Data System (ADS)

    Al-Saadi, Jassim; Szykman, James; Pierce, R. Bradley; Kittaka, Chieko; Neil, Doreen; Chu, D. Allen; Remer, Lorraine; Gumley, Liam; Prins, Elaine; Weinstock, Lewis; MacDonald, Clinton; Wayland, Richard; Dimmick, Fred; Fishman, Jack

    2005-09-01

    Accurate air quality forecasts can allow for mitigation of the health risks associated with high levels of air pollution. During September 2003, a team of NASA, NOAA, and EPA researchers demonstrated a prototype tool for improving fine particulate matter (PM2.5) air quality forecasts using satellite aerosol observations. Daily forecast products were generated from a near-real-time fusion of multiple input data products, including aerosol optical depth (AOD) from the Moderate Resolution Imaging Spectroradiometer (MODIS)/ Earth Observing System (EOS) instrument on the NASA Terra satellite, PM2.5 concentration from over 300 state/local/national surface monitoring stations, meteorological fields from the NOAA/NCEP Eta Model, and fire locations from the NOAA/National Environmental Satellite, Data, and Information Service (NESDIS) Geostationary Operational Environmental Satellite (GOES) Wildfire Automated Biomass Burning Algorithm (WF_ABBA) product. The products were disseminated via a Web interface to a small group of forecasters representing state and local air management agencies and the EPA. The MODIS data improved forecaster knowledge of synoptic-scale air pollution events, particularly over oceans and in regions devoid of surface monitors. Forecast trajectories initialized in regions of high AOD offered guidance for identifying potential episodes of poor air quality. The capability of this approach was illustrated with a case study showing that aerosol resulting from wildfires in the northwestern United States and southwestern Canada is transported across the continent to influence air quality in the Great Lakes region a few days later. The timing of this demonstration was selected to help improve the accuracy of the EPA's AIRNow (www.epa.gov/airnow/) air quality index next-day PM2.5 forecast, which began on 1 October 2003. Based on the positive response from air quality managers and forecasters, this prototype was expanded and transitioned to an operational

  13. Observationally constrained estimates of carbonaceous aerosol radiative forcing.

    PubMed

    Chung, Chul E; Ramanathan, V; Decremer, Damien

    2012-07-17

    Carbonaceous aerosols (CA) emitted by fossil and biomass fuels consist of black carbon (BC), a strong absorber of solar radiation, and organic matter (OM). OM scatters as well as absorbs solar radiation. The absorbing component of OM, which is ignored in most climate models, is referred to as brown carbon (BrC). Model estimates of the global CA radiative forcing range from 0 to 0.7 Wm(-2), to be compared with the Intergovernmental Panel on Climate Change's estimate for the pre-Industrial to the present net radiative forcing of about 1.6 Wm(-2). This study provides a model-independent, observationally based estimate of the CA direct radiative forcing. Ground-based aerosol network data is integrated with field data and satellite-based aerosol observations to provide a decadal (2001 through 2009) global view of the CA optical properties and direct radiative forcing. The estimated global CA direct radiative effect is about 0.75 Wm(-2) (0.5 to 1.0). This study identifies the global importance of BrC, which is shown to contribute about 20% to 550-nm CA solar absorption globally. Because of the inclusion of BrC, the net effect of OM is close to zero and the CA forcing is nearly equal to that of BC. The CA direct radiative forcing is estimated to be about 0.65 (0.5 to about 0.8) Wm(-2), thus comparable to or exceeding that by methane. Caused in part by BrC absorption, CAs have a net warming effect even over open biomass-burning regions in Africa and the Amazon. PMID:22753522

  14. MODIS Observation of Aerosols over Southern Africa During SAFARI 2000: Data, Validation, and Estimation of Aerosol Radiative Forcing

    NASA Technical Reports Server (NTRS)

    Ichoku, Charles; Kaufman, Yoram; Remer, Lorraine; Chu, D. Allen; Mattoo, Shana; Tanre, Didier; Levy, Robert; Li, Rong-Rong; Kleidman, Richard; Lau, William K. M. (Technical Monitor)

    2001-01-01

    Aerosol properties, including optical thickness and size parameters, are retrieved operationally from the MODIS sensor onboard the Terra satellite launched on 18 December 1999. The predominant aerosol type over the Southern African region is smoke, which is generated from biomass burning on land and transported over the southern Atlantic Ocean. The SAFARI-2000 period experienced smoke aerosol emissions from the regular biomass burning activities as well as from the prescribed burns administered on the auspices of the experiment. The MODIS Aerosol Science Team (MAST) formulates and implements strategies for the retrieval of aerosol products from MODIS, as well as for validating and analyzing them in order to estimate aerosol effects in the radiative forcing of climate as accurately as possible. These activities are carried out not only from a global perspective, but also with a focus on specific regions identified as having interesting characteristics, such as the biomass burning phenomenon in southern Africa and the associated smoke aerosol, particulate, and trace gas emissions. Indeed, the SAFARI-2000 aerosol measurements from the ground and from aircraft, along with MODIS, provide excellent data sources for a more intensive validation and a closer study of the aerosol characteristics over Southern Africa. The SAFARI-2000 ground-based measurements of aerosol optical thickness (AOT) from both the automatic Aerosol Robotic Network (AERONET) and handheld Sun photometers have been used to validate MODIS retrievals, based on a sophisticated spatio-temporal technique. The average global monthly distribution of aerosol from MODIS has been combined with other data to calculate the southern African aerosol daily averaged (24 hr) radiative forcing over the ocean for September 2000. It is estimated that on the average, for cloud free conditions over an area of 9 million square kin, this predominantly smoke aerosol exerts a forcing of -30 W/square m C lose to the terrestrial

  15. The long-term global record on Aerosol Absorption Optical Depth from TOMS and OMI observations

    NASA Astrophysics Data System (ADS)

    Torres, O.; Bhartia, P.; Ahn, C.; Veefkind, P.

    2006-12-01

    Carbonaceous aerosols from biomass burning and boreal forest fires, and desert dust lofted by the winds from the world major arid and semi-arid areas are among the most long-lived aerosol types in the Earth's atmosphere, since they often reach the free troposphere and are sometimes transported thousands of kilometers from their original sources. A lot has been learned about the global distribution of aerosol sources, and the transport patterns of these aerosol types since the development of the near-UV methods of aerosol detection and characterization using data from the TOMS series of instruments. Because both smoke and desert dust aerosols absorb UV-radiation, the TOMS aerosol sensing technique is specially suited for tracking these aerosol types over variety of surfaces including clouds and snow. TOMS aerosol observations, for instance, have been fundamental in discovering that carbonaceous aerosols associated with wild fires at mid and high latitudes often reach the lower stratosphere, and travel as far as the remote polar regions. We have recently completed the development of an improved algorithm to derive quantitative information about aerosol absorption optical depth using near-UV data. We will discuss the multi- decadal global record on aerosol absorption optical depth produced using TOMS and OMI sensors, and review the multiple contributions of the TOMS-OMI record to the current understanding of the factors that govern the observed temporal and spatial distribution of smoke and desert dust aerosols.

  16. Distributed Regional Aerosol Gridded Observation Network (DRAGON) - Korea 2012 campaign

    NASA Astrophysics Data System (ADS)

    Kim, J.; Holben, B. N.; Eck, T. F.; Jeong, U.; Kim, W. V.; Choi, M.; Kim, D. S.; Kim, B.; Kim, S.; Ghim, Y.; Kim, Y. J.; Kim, J. H.; Park, R.; Seo, M.; Song, C.; Yum, S.; Woo, J.; Yoon, S.; Lee, K.; Lee, M.; Lim, J.; Chang, I.; Jeong, M. J.; Bae, M.; Sorokin, M.; Giles, D. M.; Schafer, J.; Herman, J. R.

    2013-12-01

    One of the main objectives of Distributed Regional Aerosol Gridded Observation Network (DRAGON) campaign in Deriving Information on Surface conditions from Column and Vertically Resolved Observations Relevant to Air Quality (DISCOVER-AQ) mission is to understand the relationship between the column optical properties of the atmosphere and the surface level air quality in terms of aerosols and gases. Recently, with the cooperative efforts with NASA (National Aeronautics and Space Administration) / GSFC (Goddard Space Flight Center), Korean University research groups, and KME (Korea Ministry of Environment) / NIER (National Institute of Environmental Research), DRAGON-Korea 2012 campaign was successfully performed from March to May 2012. The campaign sites were divided into two groups, the National scale sites and Seoul metropolitan sites. Thirteen Cimel sunphotometers were distributed at National scale sites including two metropolitan cities and several remote sites. Nine Cimel sunphotometers were distributed at Seoul Metropolitan sites including several residential sites and traffic source areas. The measured datasets are being analyzed in diverse fields of air quality communities including in-situ measurement groups, satellite remote sensing groups, chemical modeling groups, and airplane measurement groups. We will introduce several preliminary results of the analysis and discuss the future planes and corporations in Korea.

  17. Aerosol Effects on the Intensity of Tropical Cyclone and the Development of Clouds in Its Outer Region

    NASA Astrophysics Data System (ADS)

    Wu, Fang; Zhao, Chuanfeng

    2016-04-01

    Aerosols have great impacts on air quality, clouds, precipitation and the energy balance of the earth. Recently studies show that aerosol can invigorate the convection near the periphery away from the eyewall, enlarge the cloud area and decrease the maximum sustained wind (MSW) of the tropical cyclone (TC). This 10 years observational study shows that aerosol has different effects to the intensity of TC and development of clouds in its outer region between TC's growing and dissipating stages. Moderate Resolution Imaging Spectroradiometer (MODIS) aerosol optical depth (AOD) and best track dataset for TCs from 2000 to 2009 in the West Pacific (WP) region are analyzed statistically. The result shows opposite correlations between AOD and MSW have been found in the two stages of TC which MSW is negatively (positively) related to AOD in the TC growing (dissipating) stage in the WP region. Similarly, in the North Atlantic region. Further analyses show that, as a low-pressure vortex with a warm core structure, TC has different responses due to the cold or warm air flow intrude. It will damage the warm core and weaken the TC when strong cold air intruding the TC. But it is favorable to the development of TC when warm air flow come into it. The outer region cloud effect by aerosol can protect the structure of warm core away from the impact of cold air flow, and AOD and MSW shows positively relationship in dissipating stage. But in growing stage, invigoration of convection draws more warm ascending air at the periphery of the storm, less air ascends in the eyewall which makes AOD and MSW negatively correlated.

  18. Reduction in intensity of Pneumocystis carinii pneumonia in mice by aerosol administration of gamma interferon.

    PubMed Central

    Beck, J M; Liggitt, H D; Brunette, E N; Fuchs, H J; Shellito, J E; Debs, R J

    1991-01-01

    Pneumocystis carinii pneumonia in patients with AIDS may result from impaired local release of gamma interferon from lung lymphocytes and subsequent failure of macrophage activation. We tested this hypothesis with mice rendered immunodeficient by selective depletion of CD4+ lymphocytes and inoculated intratracheally with P. carinii. After aerosol administration of recombinant murine gamma interferon, the intensity of P. carinii infection in these mice was reduced in comparison with that in mice not treated with gamma interferon. Histologic scoring of lung tissue did not reveal additional pulmonary inflammation attributable to gamma interferon. Aerosol administration of gamma interferon may reduce the intensity of P. carinii infection by augmentation of host defense, despite persistent CD4+ lymphocyte depletion. Images PMID:1682252

  19. Tropospheric Aerosol Climate Forcing in Clear-Sky Satellite Observations over the Oceans.

    PubMed

    Haywood; Ramaswamy; Soden

    1999-02-26

    Tropospheric aerosols affect the radiative forcing of Earth's climate, but their variable concentrations complicate an understanding of their global influence. Model-based estimates of aerosol distributions helped reveal spatial patterns indicative of the presence of tropospheric aerosols in the satellite-observed clear-sky solar radiation budget over the world's oceans. The results show that, although geographical signatures due to both natural and anthropogenic aerosols are manifest in the satellite observations, the naturally occurring sea-salt is the leading aerosol contributor to the global-mean clear-sky radiation balance over oceans. PMID:10037595

  20. Retrieval of aerosol optical thickness over snow using AATSR observations

    NASA Astrophysics Data System (ADS)

    Istomina, Larysa; von Hoyningen-Huene, Wolfgang; Rozanov, Vladimir; Kokhanovsky, Alexander; Burrows, John P.

    . 1. L.G. Istomina, W. Von Hoyningen-Huene, A.A.Kokhanovsky, V.V. Rozanov, M. Schreier, K. Dethloff, M.Stock, R. Treffeisen, A. Herber, J.P.Burrows (2008). Sensitivity study of the dual-view algorithm for aerosol optical thickness retrieval over snow and ice, Proceedings of the 2nd MERIS/(A)ATSR User Workshop, 22-26 September 2008, ESRIN, Frascati, Italy. 2. L.G. Istomina, W. Von Hoyningen-Huene, A.A. Kokhanovsky, J.P. Burrows (2009) Retrieval of aerosol optical thickness in Arctic region using dual-view AATSR observations, Proceedings of ESA Atmospheric Science Conference, 9-11 September 2009, Barcelona, Spain. 3. Y.R. Kaufman, D. Tanre, H.R. Gordon, T. Nakajima, J. Lenoble, R. Frouin, H. Grassl, B.M. Herman, M.D. King, P.M. Teillet (1997) Passive remote sensing of tropospheric aerosol and atmorpheric correction for the aerosol effect. J. Geophys. Res. 102, 16.815-16.830 4. D.Tanre, M. Herman, P.Y.Deschamps, A. De Leffe (1979) Atmosperic modeling for space measurements of ground reflectances, including bidirectional properties. Appl. Optics, 18, 21. 3587-3594

  1. Aerosol Indirect Effect Studies at Southern Great Plains During the May 2003 Intensive Operations Period

    NASA Technical Reports Server (NTRS)

    Feingold, Graham; Furrer, Reinhard; Pilewskie, Peter; Remer, Lorraine A.; Min, Qilong; Jonsson, Haflidi

    2006-01-01

    During May 2003 the Department of Energy's Atmospheric Radiation Measurement Program conducted an Intensive Operations Period (IOP) to measure the radiative effects of aerosol and clouds. A suite of both in situ and remote sensing measurements were available to measure aerosol and cloud parameters. This paper has three main goals: First, it focuses on comparison between in situ retrievals of the radiatively important drop effective radius r(sub e) and various satellite, airborne, and surface remote sensing retrievals of the same parameter. On 17 May 2003, there was a fortuitous, near-simultaneous sampling of a stratus cloud by five different methods. The retrievals of r(sub e) agree with one another to within approx.20%, which is approximately the error estimate for most methods. Second, a methodology for deriving a best estimate of r(sub e) from these different instruments, with their different physical properties and sampling volumes, is proposed and applied to the 17 May event. Third, the paper examines the response of r(sub e) to changes in aerosol on 3 days during the experiment and examines the consistency of remote sensing and in situ measurements of the effect of aerosol on r(sub e). It is shown that in spite of the generally good agreement in derived r(sub e), the magnitude of the response of r(sub e), to changes in aerosol is quite sensitive to the method of retrieving r(sub e) and to the aerosol proxy for cloud condensation nuclei. Nonphysical responses are sometimes noted, and it is suggested that further work needs to be done to refine these techniques.

  2. Ensemble-Based Assimilation of Aerosol Observations in GEOS-5

    NASA Technical Reports Server (NTRS)

    Buchard, V.; Da Silva, A.

    2016-01-01

    MERRA-2 is the latest Aerosol Reanalysis produced at NASA's Global Modeling Assimilation Office (GMAO) from 1979 to present. This reanalysis is based on a version of the GEOS-5 model radiatively coupled to GOCART aerosols and includes assimilation of bias corrected Aerosol Optical Depth (AOD) from AVHRR over ocean, MODIS sensors on both Terra and Aqua satellites, MISR over bright surfaces and AERONET data. In order to assimilate lidar profiles of aerosols, we are updating the aerosol component of our assimilation system to an Ensemble Kalman Filter (EnKF) type of scheme using ensembles generated routinely by the meteorological assimilation. Following the work performed with the first NASA's aerosol reanalysis (MERRAero), we first validate the vertical structure of MERRA-2 aerosol assimilated fields using CALIOP data over regions of particular interest during 2008.

  3. Modelled and observed changes in aerosols and surface solar radiation over Europe between 1960 and 2009

    NASA Astrophysics Data System (ADS)

    Turnock, S. T.; Spracklen, D. V.; Carslaw, K. S.; Mann, G. W.; Woodhouse, M. T.; Forster, P. M.; Haywood, J.; Johnson, C. E.; Dalvi, M.; Bellouin, N.; Sanchez-Lorenzo, A.

    2015-08-01

    Substantial changes in anthropogenic aerosols and precursor gas emissions have occurred over recent decades due to the implementation of air pollution control legislation and economic growth. The response of atmospheric aerosols to these changes and the impact on climate are poorly constrained, particularly in studies using detailed aerosol chemistry-climate models. Here we compare the HadGEM3-UKCA (Hadley Centre Global Environment Model-United Kingdom Chemistry and Aerosols) coupled chemistry-climate model for the period 1960-2009 against extensive ground-based observations of sulfate aerosol mass (1978-2009), total suspended particle matter (SPM, 1978-1998), PM10 (1997-2009), aerosol optical depth (AOD, 2000-2009), aerosol size distributions (2008-2009) and surface solar radiation (SSR, 1960-2009) over Europe. The model underestimates observed sulfate aerosol mass (normalised mean bias factor (NMBF) = -0.4), SPM (NMBF = -0.9), PM10 (NMBF = -0.2), aerosol number concentrations (N30 NMBF = -0.85; N50 NMBF = -0.65; and N100 NMBF = -0.96) and AOD (NMBF = -0.01) but slightly overpredicts SSR (NMBF = 0.02). Trends in aerosol over the observational period are well simulated by the model, with observed (simulated) changes in sulfate of -68 % (-78 %), SPM of -42 % (-20 %), PM10 of -9 % (-8 %) and AOD of -11 % (-14 %). Discrepancies in the magnitude of simulated aerosol mass do not affect the ability of the model to reproduce the observed SSR trends. The positive change in observed European SSR (5 %) during 1990-2009 ("brightening") is better reproduced by the model when aerosol radiative effects (ARE) are included (3 %), compared to simulations where ARE are excluded (0.2 %). The simulated top-of-the-atmosphere aerosol radiative forcing over Europe under all-sky conditions increased by > 3.0 W m-2 during the period 1970-2009 in response to changes in anthropogenic emissions and aerosol concentrations.

  4. Direct and Semi-direct Radiative Responses to Observation-Constrained Aerosol Absorption over S Asia

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    Climate impacts of aerosols over S. Asia have been studied extensively in both models and observations. However, discrepancies between observed and modeled aerosol concentrations and optical properties have hindered our understanding of the aerosol influences on the regional monsoon circulation and rainfall. We present an in-depth examination of direct and semi-direct radiative responses due to aerosols on the latitudinal heating gradient and cloud distribution, with observational constraints on solar absorption by aerosols. Regional distributions of aerosol concentration are simulated with a 12-km regional climate model (WRF-Chem) driven by the NCEP analysis data from August 2011 to March 2012. During this time period, the ground-based measurements of aerosols and clouds, surface radiation, water vapor, and temperature were taken at Nainital (29.38°N, 79.45°E) during the DOE Ganges Valley Experiment (GVAX). This data set, which is available at high temporal resolution (hourly), is used to evaluate and constrain the simulated wavelength dependence of aerosol absorption and the correlation with changes in surface radiation, cloud base height and liquid water content for the entire post-monsoon period. The analysis is extended to a regional scale by comparing with satellite observation of absorbing aerosol optical depth (OMI) and cloud properties (MODIS). Preliminary results show good agreement in monthly variations of simulated and observed aerosol optical depth (AOD) except during periods of high observed AOD. Initial analysis indicates a possible local origin for the aerosols that is not captured in the model at present. Furthermore, analysis of the spectrally resolved aerosol absorption measurements indicates that these local aerosols exhibit strong absorption in near-UV and visible wavelengths. A large fraction of increased absorption during October and November (local fall harvest season) is attributable to the super-micron sized aerosol particles. In

  5. Characterization of Spectral Absorption Properties of Aerosols Using Satellite Observations

    NASA Technical Reports Server (NTRS)

    Torres, O.; Jethva, H.; Bhartia, P. K.; Ahn, C.

    2012-01-01

    The wavelength-dependence of aerosol absorption optical depth (AAOD) is generally represented in terms of the Angstrom Absorption Exponent (AAE), a parameter that describes the dependence of AAOD with wavelength. The AAE parameter is closely related to aerosol composition. Black carbon (BC) containing aerosols yield AAE values near unity whereas Organic carbon (OC) aerosol particles are associated with values larger than 2. Even larger AAE values have been reported for desert dust aerosol particles. Knowledge of spectral AAOD is necessary for the calculation of direct radiative forcing effect of aerosols and for inferring aerosol composition. We have developed a satellitebased method of determining the spectral AAOD of absorbing aerosols. The technique uses high spectral resolution measurements of upwelling radiation from scenes where absorbing aerosols lie above clouds as indicated by the UV Aerosol Index. For those conditions, the satellite measured reflectance (rho lambda) is approximately given by Beer's law rho lambda = rho (sub 0 lambda) e (exp -mtau (sub abs lambda)) where rho(sub 0 lambda) is the cloud reflectance, m is the geometric slant path and tau (sub abs lambda) is the spectral AAOD. The rho (sub 0 lambda) term is determined by means of radiative transfer calculations using as input the cloud optical depth derived as described in Torres et al. [JAS, 2012] that accounts for the effects of aerosol absorption. In the second step, corrections for molecular and aerosol scattering effects are applied to the cloud reflectance term, and the spectral AAOD is then derived by inverting the equation above. The proposed technique will be discussed in detail and application results will be presented. The technique can be easily applied to hyper-spectral satellite measurements that include UV such as OMI, GOME and SCIAMACHY, or to multi-spectral visible measurements by other sensors provided that the aerosol-above-cloud events are easily identified.

  6. Meridional gradients in aerosol vertical distribution over Indian Mainland: Observations and model simulations

    NASA Astrophysics Data System (ADS)

    Prijith, S. S.; Suresh Babu, S.; Lakshmi, N. B.; Satheesh, S. K.; Krishna Moorthy, K.

    2016-01-01

    Multi-year observations from the network of ground-based observatories (ARFINET), established under the project 'Aerosol Radiative Forcing over India' (ARFI) of Indian Space Research Organization and space-borne lidar 'Cloud Aerosol Lidar with Orthogonal Polarization' (CALIOP) along with simulations from the chemical transport model 'Goddard Chemistry Aerosol Radiation and Transport' (GOCART), are used to characterize the vertical distribution of atmospheric aerosols over the Indian landmass and its spatial structure. While the vertical distribution of aerosol extinction showed higher values close to the surface followed by a gradual decrease at increasing altitudes, a strong meridional increase is observed in the vertical spread of aerosols across the Indian region in all seasons. It emerges that the strong thermal convections cause deepening of the atmospheric boundary layer, which although reduces the aerosol concentration at lower altitudes, enhances the concentration at higher elevations by pumping up more aerosols from below and also helping the lofted particles to reach higher levels in the atmosphere. Aerosol depolarization ratios derived from CALIPSO as well as the GOCART simulations indicate the dominance of mineral dust aerosols during spring and summer and anthropogenic aerosols in winter. During summer monsoon, though heavy rainfall associated with the Indian monsoon removes large amounts of aerosols, the prevailing southwesterly winds advect more marine aerosols over to landmass (from the adjoining oceans) leading to increase in aerosol loading at lower altitudes than in spring. During spring and summer months, aerosol loading is found to be significant, even at altitudes as high as 4 km, and this is proposed to have significant impacts on the regional climate systems such as Indian monsoon.

  7. Global fine-mode aerosol radiative effect, as constrained by comprehensive observations

    NASA Astrophysics Data System (ADS)

    Chung, Chul E.; Chu, Jung-Eun; Lee, Yunha; van Noije, Twan; Jeoung, Hwayoung; Ha, Kyung-Ja; Marks, Marguerite

    2016-07-01

    Aerosols directly affect the radiative balance of the Earth through the absorption and scattering of solar radiation. Although the contributions of absorption (heating) and scattering (cooling) of sunlight have proved difficult to quantify, the consensus is that anthropogenic aerosols cool the climate, partially offsetting the warming by rising greenhouse gas concentrations. Recent estimates of global direct anthropogenic aerosol radiative forcing (i.e., global radiative forcing due to aerosol-radiation interactions) are -0.35 ± 0.5 W m-2, and these estimates depend heavily on aerosol simulation. Here, we integrate a comprehensive suite of satellite and ground-based observations to constrain total aerosol optical depth (AOD), its fine-mode fraction, the vertical distribution of aerosols and clouds, and the collocation of clouds and overlying aerosols. We find that the direct fine-mode aerosol radiative effect is -0.46 W m-2 (-0.54 to -0.39 W m-2). Fine-mode aerosols include sea salt and dust aerosols, and we find that these natural aerosols result in a very large cooling (-0.44 to -0.26 W m-2) when constrained by observations. When the contribution of these natural aerosols is subtracted from the fine-mode radiative effect, the net becomes -0.11 (-0.28 to +0.05) W m-2. This net arises from total (natural + anthropogenic) carbonaceous, sulfate and nitrate aerosols, which suggests that global direct anthropogenic aerosol radiative forcing is less negative than -0.35 W m-2.

  8. Retrieval of Aerosol Optical Depth Above Clouds from OMI Observations: Sensitivity Analysis, Case Studies

    NASA Technical Reports Server (NTRS)

    Torres, O.; Jethva, H.; Bhartia, P. K.

    2012-01-01

    A large fraction of the atmospheric aerosol load reaching the free troposphere is frequently located above low clouds. Most commonly observed aerosols above clouds are carbonaceous particles generally associated with biomass burning and boreal forest fires, and mineral aerosols originated in arid and semi-arid regions and transported across large distances, often above clouds. Because these aerosols absorb solar radiation, their role in the radiative transfer balance of the earth atmosphere system is especially important. The generally negative (cooling) top of the atmosphere direct effect of absorbing aerosols, may turn into warming when the light-absorbing particles are located above clouds. The actual effect depends on the aerosol load and the single scattering albedo, and on the geometric cloud fraction. In spite of its potential significance, the role of aerosols above clouds is not adequately accounted for in the assessment of aerosol radiative forcing effects due to the lack of measurements. In this paper we discuss the basis of a simple technique that uses near-UV observations to simultaneously derive the optical depth of both the aerosol layer and the underlying cloud for overcast conditions. The two-parameter retrieval method described here makes use of the UV aerosol index and reflectance measurements at 388 nm. A detailed sensitivity analysis indicates that the measured radiances depend mainly on the aerosol absorption exponent and aerosol-cloud separation. The technique was applied to above-cloud aerosol events over the Southern Atlantic Ocean yielding realistic results as indicated by indirect evaluation methods. An error analysis indicates that for typical overcast cloudy conditions and aerosol loads, the aerosol optical depth can be retrieved with an accuracy of approximately 54% whereas the cloud optical depth can be derived within 17% of the true value.

  9. Aerosol and cloud droplet number concentrations observed in marine stratocumulus

    SciTech Connect

    Vong, R.J.; Covert, D.S.

    1995-12-01

    The relationship between measurements of cloud droplet number concentration and cloud condensation nuclei (CCN) concentration, as inferred from aerosol size spectra, was investigated at a {open_quote}clean air{close_quote}, marine site (Cheeka Peak) located near the coast of the Olympic Peninsula in Washington State. Preliminary results demonstrated that cloud droplet number increased and droplet diameter decreased as aerosol number concentration (CCN) increased. These results support predictions of a climate cooling due to any future increases in marine aerosol concentrations.

  10. Aerosol Optical Properties in Southeast Asia From AERONET Observations

    NASA Astrophysics Data System (ADS)

    Eck, T. F.; Holben, B. N.; Boonjawat, J.; Le, H. V.; Schafer, J. S.; Reid, J. S.; Dubovik, O.; Smirnov, A.

    2003-12-01

    There is little published data available on measured optical properties of aerosols in the Southeast Asian region. The AERONET project and collaborators commenced monitoring of aerosol optical properties in February 2003 at four sites in Thailand and two sites in Viet Nam to measure the primarily anthropogenic aerosols generated by biomass burning and fossil fuel combustion/ industrial emissions. Automatic sun/sky radiometers at each site measured spectral aerosol optical depth in 7 wavelengths from 340 to 1020 nm and combined with directional radiances in the almucantar, retrievals were made of spectral single scattering albedo and aerosol size distributions. Angstrom exponents, size distributions and spectral single scattering albedo of primarily biomass burning aerosols at rural sites are compared to measurements made at AERONET sites in other major biomass burning regions in tropical southern Africa, South America, and in boreal forest regions. Additionally, the aerosol single scattering albedo and size distributions measured in Bangkok, Thailand are compared with those measured at other urban sites globally. The influences of aerosols originating from other regions outside of Southeast Asia are analyzed using trajectory analyses. Specifically, cases of aerosol transport and mixing from Southern China and from India are presented.

  11. Weekly periodicities of aerosol properties observed at an urban location in India

    NASA Astrophysics Data System (ADS)

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

    2011-07-01

    Multi-year (~ 7 years) observations of aerosol optical and microphysical properties were conducted at a tropical urban location in Bangalore, India. As a consequence of rapid urbanization, Bangalore presents high local atmospheric emissions, which makes it an interesting site to study the effect of anthropogenic activities on aerosol properties. It has been found that both column (aerosol optical depth, AOD) and ground-level measurements (black carbon (BC) and composite aerosol mass) exhibit a weekly cycle with low aerosol concentrations on weekends. In comparison to the weekdays, the weekend reductions of aerosol optical depth, black carbon and composite aerosol mass concentrations were ~ 15%, 25% and 24%, respectively. The magnitude of weekend reduction of black carbon is as much as ~ 1 μg m - 3 . The similarity in the weekly cycle between the column and surface measurements suggests that the aerosol column loading at this location is governed by local anthropogenic emissions. The strongest weekly cycle in composite aerosol mass concentration was observed in the super micron mass range (> 1 μm). The weekly cycle of composite aerosol mass in the sub micron mass range (< 1 μm) was weak in comparison to the super micron aerosol mass.

  12. Weekly periodicities of aerosol properties observed at an urban location in India

    SciTech Connect

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

    2011-07-01

    Multi-year (~7 years) observations of aerosol optical and microphysical properties were conducted at a tropical urban location in Bangalore, India. As a consequence of rapid urbanization, Bangalore presents high local atmospheric emissions, which makes it an interesting site to study the effect of anthropogenic activities on aerosol properties. It has been found that both column (aerosol optical depth, AOD) and ground-level measurements (black carbon (BC) and composite aerosol mass) exhibit a weekly cycle with low aerosol concentrations on weekends. In comparison to the weekdays, the weekend reductions of aerosol optical depth, black carbon and composite aerosol mass concentrations were ~15%, 25% and 24%, respectively. The magnitude of weekend reduction of black carbon is as much as ~1 μg m-3. The similarity in the weekly cycle between the column and surface measurements suggests that the aerosol column loading at this location is governed by local anthropogenic emissions. The strongest weekly cycle in composite aerosol mass concentration was observed in the super micron mass range (>1 μm). The weekly cycle of composite aerosol mass in the sub micron mass range (<1 μm) was weak in comparison to the super micron aerosol mass.

  13. Observed holiday aerosol reduction and temperature cooling over East Asia

    NASA Astrophysics Data System (ADS)

    Gong, Dao-Yi; Wang, Wenshan; Qian, Yun; Bai, Wenbing; Guo, Yuanxi; Mao, Rui

    2014-06-01

    The air pollution in Chinese Spring Festival (CSF) period over eastern China was investigated using the long-term observations from 2001 to 2012 over 323 stations. The dominant feature of the pollutants around the CSF holidays is the significant reduction of concentration. During the 10day period around the CSF (but excluding the Lunar New Year's Day, LNYD), PM10 experiences a reduction of -9.24%. In association with the aerosol reduction, temperature significantly drops over eastern China. From the third day before the LNYD to the second day after, the daily mean temperature anomaly is -0.81°C, and for no-rain days the anomaly is -0.85°C. The simultaneous anomalies of the daily maximum and minimum temperatures are -0.79°C and -0.82°C, respectively. From the third day to seventh day after the LNYD, the significant negative temperature anomalies move out of China, extending to a broad area from the South China Sea to the western North Pacific. Between the 8th and the 12th days, the significant temperature anomalies can still be found over 140°E-160°E and 15°N-25°N. The reduced downward longwave flux might play an important role in holiday cooling. The possible atmospheric feedback is discernable. The thermal and circulation configuration accompanying the cooling favors baroclinic interaction between upper and lower troposphere for the midlatitude cyclone. The anomalous cyclone becomes mature during the third to the seventh day after the LNYD and disappears 12 days later. The anomalous northern winds in association with the cyclone decrease the temperature and also help disperse the holiday aerosols over eastern China.

  14. Evaluation of sulfate aerosol optical depths over the North Atlantic and comparison with satellite observations

    SciTech Connect

    Berkowitz, C.M.; Ghan, S.J.; Benkovitz, C.M.; Wagener, R.; Nemesure, S.; Schwartz, S.E.

    1993-11-01

    It has been postulated that scattering of sunlight by aerosols can significantly reduce the amount of solar energy absorbed by the climate system. Aerosol measurement programs alone cannot provide all the information needed to evaluate the radiative forcing due to anthropogenic aerosols. Thus, comprehensive global-scale aerosol models, properly validated against surface-based and satellite measurements, are a fundamental tool for evaluating the impacts of aerosols on the planetary radiation balance. Analyzed meteorological fields from the European Centre for Medium-Range Weather Forecasts are used to drive a modified version of the PNL Global Chemistry Model, applied to the atmospheric sulfur cycle. The resulting sulfate fields are used to calculate aerosol optical depths, which in turn are compared to estimates of aerosol optical depth based on satellite observations.

  15. Aerosol Observability and Predictability: From Research to Operations for Chemical Weather Forecasting. Lagrangian Displacement Ensembles for Aerosol Data Assimilation

    NASA Technical Reports Server (NTRS)

    da Silva, Arlindo

    2010-01-01

    A challenge common to many constituent data assimilation applications is the fact that one observes a much smaller fraction of the phase space that one wishes to estimate. For example, remotely sensed estimates of the column average concentrations are available, while one is faced with the problem of estimating 3D concentrations for initializing a prognostic model. This problem is exacerbated in the case of aerosols because the observable Aerosol Optical Depth (AOD) is not only a column integrated quantity, but it also sums over a large number of species (dust, sea-salt, carbonaceous and sulfate aerosols. An aerosol transport model when driven by high-resolution, state-of-the-art analysis of meteorological fields and realistic emissions can produce skillful forecasts even when no aerosol data is assimilated. The main task of aerosol data assimilation is to address the bias arising from inaccurate emissions, and Lagrangian misplacement of plumes induced by errors in the driving meteorological fields. As long as one decouples the meteorological and aerosol assimilation as we do here, the classic baroclinic growth of error is no longer the main order of business. We will describe an aerosol data assimilation scheme in which the analysis update step is conducted in observation space, using an adaptive maximum-likelihood scheme for estimating background errors in AOD space. This scheme includes e explicit sequential bias estimation as in Dee and da Silva. Unlikely existing aerosol data assimilation schemes we do not obtain analysis increments of the 3D concentrations by scaling the background profiles. Instead we explore the Lagrangian characteristics of the problem for generating local displacement ensembles. These high-resolution state-dependent ensembles are then used to parameterize the background errors and generate 3D aerosol increments. The algorithm has computational complexity running at a resolution of 1/4 degree, globally. We will present the result of

  16. A modeling perspective of the ChArMEx intensive campaign: origin of photo-oxidant and organic aerosol formation

    NASA Astrophysics Data System (ADS)

    Cholakian, Arineh; Beekmann, Matthias; Siour, Guillaume; Coll, Isabelle; Colette, Augustin; Gros, Valerie; Marchand, Nicolas; Sciare, Jean; Colomb, Aurélie; Gheusi, François; Sauvage, Stéphane

    2016-04-01

    During the summers of 2013 and 2014, two three-week intensive campaigns took place over the western Mediterranean in order to investigate the origins of photo-oxidants as well as the sources and processes of formation of organic aerosols in this region. Within the frame of the MISTRAL/ChArMEx program, an extensive number of chemical compounds were investigated by means of ground-based and also airborne measurements. In this paper, a modeling perspective of the 2013 campaign is given, using the CHIMERE chemistry-transport model, dealing with two aspects: 1) representativeness of the simulations with respect to the complex orography of Cape Corsica, 2) evaluation of secondary organic aerosol simulations in the western Mediterranean region with different model configurations using a variety of experimental data. The model has been configured in a way to fit the specificities of this unique region. The base simulations are performed in a domain covering the entire Europe as well as the northern Africa with a low resolution (30 km). In order to take into account the orographic complexity of the area where the ground-based measurements were performed (Ersa, Cape Corsica), nested simulations with a high resolution (1km horizontal resolution) focused on this site were performed with the goal of increasing the representativeness of the simulations. Still, this resolution does not allow to correctly represent the altitude of the Cape Corsica measurement site (533 m asl). To solve this problem, a large number of grid cells in the vicinity of the measurements site, all having different altitudes, were used to find the extrapolated concentration of an indicative list of species towards the exact altitude of the aforementioned site and to estimate an orographic representativeness error, which was shown to be less important for organic aerosols among said species. Alongside the base simulations, other series of simulations using multiple configurations of the Volatility Basis Set

  17. Observational Study and Parameterization of Aerosol-fog Interactions

    NASA Astrophysics Data System (ADS)

    Duan, J.; Guo, X.; Liu, Y.; Fang, C.; Su, Z.; Chen, Y.

    2014-12-01

    Studies have shown that human activities such as increased aerosols affect fog occurrence and properties significantly, and accurate numerical fog forecasting depends on, to a large extent, parameterization of fog microphysics and aerosol-fog interactions. Furthermore, fogs can be considered as clouds near the ground, and enjoy an advantage of permitting comprehensive long-term in-situ measurements that clouds do not. Knowledge learned from studying aerosol-fog interactions will provide useful insights into aerosol-cloud interactions. To serve the twofold objectives of understanding and improving parameterizations of aerosol-fog interactions and aerosol-cloud interactions, this study examines the data collected from fogs, with a focus but not limited to the data collected in Beijing, China. Data examined include aerosol particle size distributions measured by a Passive Cavity Aerosol Spectrometer Probe (PCASP-100X), fog droplet size distributions measured by a Fog Monitor (FM-120), Cloud Condensation Nuclei (CCN), liquid water path measured by radiometers and visibility sensors, along with meteorological variables measured by a Tethered Balloon Sounding System (XLS-Ⅱ) and Automatic Weather Station (AWS). The results will be compared with low-level clouds for similarities and differences between fogs and clouds.

  18. Modelled and observed changes in aerosols and surface solar radiation over Europe between 1960 and 2009

    NASA Astrophysics Data System (ADS)

    Turnock, S. T.; Spracklen, D. V.; Carslaw, K. S.; Mann, G. W.; Woodhouse, M. T.; Forster, P. M.; Haywood, J.; Johnson, C. E.; Dalvi, M.; Bellouin, N.; Sanchez-Lorenzo, A.

    2015-05-01

    Substantial changes in anthropogenic aerosols and precursor gas emissions have occurred over recent decades due to the implementation of air pollution control legislation and economic growth. The response of atmospheric aerosols to these changes and the impact on climate are poorly constrained, particularly in studies using detailed aerosol chemistry climate models. Here we compare the HadGEM3-UKCA coupled chemistry-climate model for the period 1960 to 2009 against extensive ground based observations of sulfate aerosol mass (1978-2009), total suspended particle matter (SPM, 1978-1998), PM10 (1997-2009), aerosol optical depth (AOD, 2000-2009) and surface solar radiation (SSR, 1960-2009) over Europe. The model underestimates observed sulfate aerosol mass (normalised mean bias factor (NMBF) = -0.4), SPM (NMBF = -0.9), PM10 (NMBF = -0.2) and aerosol optical depth (AOD, NMBF = -0.01) but slightly overpredicts SSR (NMBF = 0.02). Trends in aerosol over the observational period are well simulated by the model, with observed (simulated) changes in sulfate of -68% (-78%), SPM of -42% (-20%), PM10 of -9% (-8%) and AOD of -11% (-14%). Discrepancies in the magnitude of simulated aerosol mass do not affect the ability of the model to reproduce the observed SSR trends. The positive change in observed European SSR (5%) during 1990-2009 ("brightening") is better reproduced by the model when aerosol radiative effects (ARE) are included (3%), compared to simulations where ARE are excluded (0.2%). The simulated top-of-the-atmosphere aerosol radiative forcing over Europe under all-sky conditions increased by 3 W m-2 during the period 1970-2009 in response to changes in anthropogenic emissions and aerosol concentrations.

  19. Aerosol Single-Scattering Albedo and Asymmetry Parameter from MFRSR Observations during the ARM Aerosol IOP 2003

    SciTech Connect

    Kassianov, Evgueni I.; Flynn, Connor J.; Ackerman, Thomas P.; Barnard, James C.

    2007-06-15

    Multi-filter Rotating Shadowband Radiometers (MFRSRs) provide routine measurements of the aerosol optical depth ( << OLE Object: Microsoft Equation 3.0 >> ) at six wavelengths (0.415, 0.5, 0.615, 0.673, 0.870 and 0.94  << OLE Object: Picture (Metafile) >> ). The single-scattering albedo ( << OLE Object: Microsoft Equation 3.0 >> ) is typically estimated from the MFRSR measurements by assuming the asymmetry parameter ( << OLE Object: Microsoft Equation 3.0 >> ). In most instances, however, it is not easy to set an appropriate value of << OLE Object: Microsoft Equation 3.0 >> due to its strong temporal and spatial variability. Here, we introduce and validate an updated version of our retrieval technique that allows one to estimate simultaneously << OLE Object: Microsoft Equation 3.0 >> and << OLE Object: Microsoft Equation 3.0 >> for different types of aerosol. We use the aerosol and radiative properties obtained during the Atmospheric Science Program (ARM) Aerosol Intensive Operational Period (IOP) to validate our retrieval in two ways. First, the MFRSR-retrieved optical properties are compared with those obtained from independent surface, Aerosol Robotic Network (AERONET) and aircraft measurements. The MFRSR-retrieved optical properties are in reasonable agreement with these independent measurements. Second, we perform radiative closure experiments using the MFRSR-retrieved optical properties. The calculated broadband values of the direct and diffuse fluxes are comparable (~ 5 << OLE Object: Microsoft Equation 3.0 >> ) to those obtained from measurements.

  20. Aerosol-Precipitation Responses Deduced from Ship tracks as Observed by CloudSat

    NASA Astrophysics Data System (ADS)

    Christensen, M.; Stephens, G. L.

    2011-12-01

    Ship tracks, produced from the exhaust plumes of ocean going vessels were analyzed using the 94-GHZ cloud profiling radar on the CloudSat satellite to examine the precipitation response of marine stratocumulus to changes in aerosol concentration. Ship tracks provide an ideal laboratory to study this response because the regions of clouds that are heavily contaminated by pollution can be separated from adjacent regions of clouds formed in the clean marine boundary layer. Several hundred ship tracks, coinciding with the radar and lidar observations from CloudSat and Calipso, were identified in MODIS imagery. The results demonstrate that, aerosol plumes from ships tend to decrease the spatial extent of rainfall (rain cover fraction) and intensity compared to the nearby pristine clouds. However, there were a substantial fraction of cases (30%), which exhibited increased rainfall. The sign and strength of the precipitation response was strongly tied to the mesoscale structure of the clouds. When the clouds exhibited closed cellular structures, liquid water amount, rainfall (-63%), and rain cover fraction significantly decreased (-55%). These reductions in rainfall were primarily associated with the decrease in rain cover fraction over the ship track domain. The opposite occurred in the open cell regime. Ship plumes ingested into this regime resulted in deeper, wetter, rainier, and brighter clouds, where rainfall increased by 88% primarily due to changes in intensity and to a lesser extent rain cover fraction. Microphysical changes almost always led to significantly smaller droplet radii in ship tracks, even when precipitation was increased. On the other hand, macrophysical changes (liquid water path) varied in magnitude and sign, and typically followed the direction of the precipitation response. The results presented here underline the need to consider the mesoscale structure of stratocumulus when examining the cloud dynamic response to changes in aerosol concentration.

  1. Radiative effects of aerosols at an urban location in southern India: Observations versus model

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

    The radiative impact of aerosols is one of the largest sources of uncertainty in estimating anthropogenic climate perturbations. Here we have used independent ground-based radiometer measurements made simultaneously with comprehensive measurements of aerosol microphysical and optical properties at a highly populated urban site, Bangalore (13.02°N, 77.6°E) in southern India during a dedicated campaign during winter of 2004 and summer and pre-monsoon season of 2005. We have also used longer term measurements carried out at this site to present general features of aerosols over this region. The aerosol radiative impact assessments were made from direct measurements of ground reaching irradiance as well as by incorporating measured aerosol properties into a radiative transfer model. Large discrepancies were observed between measured and modeled (using radiative transfer models, which employed measured aerosol properties) radiative impacts. It appears that the presence of elevated aerosol layers and (or) inappropriate description of aerosol state of mixing are (is) responsible for the discrepancies. On a monthly scale reduction of surface irradiance due to the presence of aerosols (estimated using radiative flux measurements) varies from 30 to 65 W m -2. The lowest values in surface radiative impact were observed during June when there is large reduction in aerosol as a consequence of monsoon rainfall. Large increase in aerosol-induced surface radiative impact was observed from winter to summer. Our investigations re-iterate the inadequacy of aerosol measurements at the surface alone and importance of representing column properties (using vertical profiles) accurately in order to assess aerosol-induced climate changes accurately.

  2. Aerosol Indirect Effect on Warm Clouds over Eastern China Using Combined CALIOP and MODIS Observations

    NASA Astrophysics Data System (ADS)

    Guo, Jianping; Wang, Fu; Huang, Jingfeng; Li, Xiaowen

    2015-04-01

    Aerosol, one of key components of the climate system, is highly variable, both temporally and spatially. It often exerts great influences on the cloud-precipitation chain processes by serving as CCN/IN, altering cloud microphysics and its life cycle. Yet, the aerosol indirect effect on clouds remains largely unknown, because the initial changes in clouds due to aerosols may be enhanced or dampened by such feedback processes as modified cloud dynamics, or evaporation of the smaller droplets due to the competition for water vapor. In this study, we attempted to quantify the aerosol effects on warm cloud over eastern China, based on near-simultaneous retrievals from MODIS/AQUA, CALIOP/CALIPSO and CPR/CLOUDSAT during the period 2006 to 2010. The seasonality of aerosol from ground-based PM10 is quite different from that estimated from MODIS AOD. This result is corroborated by lower level profile of aerosol occurrence frequency from CALIOP, indicating the significant role CALIOP could play in aerosol-cloud interaction. The combined use of CALIOP and CPR facilitate the process to exactly determine the (vertical) position of warm cloud relative to aerosol, out of six scenarios in terms of aerosol-cloud mixing status in terms of aerosol-cloud mixing status, which shows as follows: AO (Aerosol only), CO (Cloud only), SASC (Single aerosol-single cloud), SADC (single aerosol-double cloud), DASC (double aerosol-single cloud), and others. Results shows that about 54% of all the cases belong to mixed status, among all the collocated aerosol-cloud cases. Under mixed condition, a boomerang shape is observed, i.e., reduced cloud droplet radius (CDR) is associated with increasing aerosol at moderate aerosol pollution (AOD<0.4), becoming saturated at AOD of 0.5, followed by an increase in CDR with aerosol. In contrast, there is no such boomerang shape found for (aerosol-cloud) separated cases. We categorize dataset into warm-season and cold-season subsets to figure out how the

  3. Observational Evidence of Aerosol Enhancement of Lightning Activity and Convective Invigoration

    NASA Technical Reports Server (NTRS)

    Yuan, Tianle; Remer, Lorraine A.; Pickering, Kenneth E.; Yu, Hongbin

    2011-01-01

    Lightning activity over the West Pacific Ocean east of the Philippines is usually much less frequent than over the nearby maritime continents. However, in 2005 the Lightning Imaging Sensor (LIS) aboard the TRMM satellite observed anomalously high lightning activity in that area. In the same year the Moderate resolution Imaging Spectroradiometer (MODIS) measured anomalously high aerosol loading. The high aerosol loading was traced to volcanic activity, and not to any factor linked to meteorology, disentangling the usual convolution between aerosols and meteorology. We show that in general lightning activity is tightly correlated with aerosol loadings at both inter-annual and biweekly time scales. We estimate that a approximately 60% increase in aerosol loading leads to more than 150% increase in lightning flashes. Aerosols increase lightning activity through modification of cloud microphysics. Cloud ice particle sizes are reduced and cloud glaciation is delayed to colder temperature when aerosol loading is increased. TRMM precipitation radar measurements indicate that anomalously high aerosol loading is associated with enhanced cloud mixed phase activity and invigorated convection over the maritime ocean. These observed associations between aerosols, cloud microphysics, morphology and lightning activity are not related to meteorological variables or ENSO events. The results have important implications for understanding the variability of lightning and resulting aerosol-chemistry interactions.

  4. 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.

  5. Observations of aerosol light scattering, absorption, and particle morphology changes as a function of relative humidity

    NASA Astrophysics Data System (ADS)

    Arnott, W. P.; Lewis, K.; Paredes-Miranda, G.; Winter, S.; Day, D.; Chakrabarty, R.; Moosmuller, H.; Jimenez, J. L.; Ulbrich, I.; Huffman, A.; Onasch, T.; Trimborn, A.; Kreidenweis, S.; Carrico, C.; Wold, C.; Lincoln, E.; Freeborn, P.; Hao, W.; McMeeking, G.

    2006-12-01

    A very interesting case of smoke aerosol with very low single scattering albedo, yet very large hygroscopic growth for scattering is presented. Several samples of chamise (Adenostoma fasciculatum), a common and often dominant species in California chaparral, were recently burned at the USFS Fire Science Laboratory in Missoula Montana, and aerosol optics and chemistry were observed, along with humidity-dependent light scattering, absorption, and particle morphology. Photoacoustic measurements of light absorption by two instruments at 870 nm, one on the dry channel, one on the humidified channel, showed strong reduction of aerosol light absorption with RH above 65 percent, and yet a strong increase in light scattering was observed both at 870 nm and 550 nm with nephelometers. Multispectral measurements of aerosol light absorption indicated an Angstrom coefficient for absorption near unity for the aerosols from chamise combustion. It is argued that the hygroscopic growth of scattering is due to uptake of water by the sulfur bearing aerosol. Furthermore, the reduction of aerosol light absorption is argued to be due to the collapse of chain aggregate aerosol as the RH increases wherein the interior of aerosol does no longer contribute to absorption. Implications for biomass burning in general are that humidity processing of aerosols from this source and others like it tends to substantially increase its single scattering albedo, probably in a non-reversible manner. The chemical pathway to hygroscopicity will be addressed.

  6. Multiangle Imaging Spectroradiometer (MISR) Global Aerosol Optical Depth Validation Based on 2 Years of Coincident Aerosol Robotic Network (AERONET) Observations

    NASA Technical Reports Server (NTRS)

    Kahn, Ralph A.; Gaitley, Barbara J.; Martonchik, John V.; Diner, David J.; Crean, Kathleen A.; Holben, Brent

    2005-01-01

    Performance of the Multiangle Imaging Spectroradiometer (MISR) early postlaunch aerosol optical thickness (AOT) retrieval algorithm is assessed quantitatively over land and ocean by comparison with a 2-year measurement record of globally distributed AERONET Sun photometers. There are sufficient coincident observations to stratify the data set by season and expected aerosol type. In addition to reporting uncertainty envelopes, we identify trends and outliers, and investigate their likely causes, with the aim of refining algorithm performance. Overall, about 2/3 of the MISR-retrieved AOT values fall within [0.05 or 20% x AOT] of Aerosol Robotic Network (AERONET). More than a third are within [0.03 or 10% x AOT]. Correlation coefficients are highest for maritime stations (approx.0.9), and lowest for dusty sites (more than approx.0.7). Retrieved spectral slopes closely match Sun photometer values for Biomass burning and continental aerosol types. Detailed comparisons suggest that adding to the algorithm climatology more absorbing spherical particles, more realistic dust analogs, and a richer selection of multimodal aerosol mixtures would reduce the remaining discrepancies for MISR retrievals over land; in addition, refining instrument low-light-level calibration could reduce or eliminate a small but systematic offset in maritime AOT values. On the basis of cases for which current particle models are representative, a second-generation MISR aerosol retrieval algorithm incorporating these improvements could provide AOT accuracy unprecedented for a spaceborne technique.

  7. Spatial boundaries of Aerosol Robotic Network observations over the Mediterranean basin

    NASA Astrophysics Data System (ADS)

    Mishra, A. K.; Rudich, Y.; Koren, I.

    2016-03-01

    Accurate knowledge of aerosol variability on a relatively high spatiotemporal scale is needed for better assessment of aerosol radiative effects and aerosol-climate interactions. We investigated the spatial boundaries of the Aerosol Robotic Network (AERONET) observations over the Mediterranean basin using a statistical approach. We used 13 years (2002-2014) of aerosol optical depth (AOD) measurements from the Moderate Resolution Imaging Spectroradiometer (MODIS) and 15 AERONET sites around the Mediterranean basin. The gridded correlation maps show moderate to high correlations (R > 0.5) around each AERONET site up to ~200-500 km radius depending on location. Such analyses provide information on the spatial domain in which the AERONET measurements can be reliably used per site. The statistical model provides a better daytime AOD product on finer temporal resolution with higher spatial coverage as compared to using AERONET/MODIS observations separately. The findings from this study can be useful for the assimilation-based model forecasting of aerosol properties.

  8. Long-range transport and mixing of aerosol sources during the 2013 North American biomass burning episode: analysis of multiple lidar observations in the western Mediterranean basin

    NASA Astrophysics Data System (ADS)

    Ancellet, Gerard; Pelon, Jacques; Totems, Julien; Chazette, Patrick; Bazureau, Ariane; Sicard, Michaël; Di Iorio, Tatiana; Dulac, Francois; Mallet, Marc

    2016-04-01

    Long-range transport of biomass burning (BB) aerosols between North America and the Mediterranean region took place in June 2013. A large number of ground-based and airborne lidar measurements were deployed in the western Mediterranean during the Chemistry-AeRosol Mediterranean EXperiment (ChArMEx) intensive observation period. A detailed analysis of the potential North American aerosol sources is conducted including the assessment of their transport to Europe using forward simulations of the FLEXPART Lagrangian particle dispersion model initialized using satellite observations by MODIS and CALIOP. The three-dimensional structure of the aerosol distribution in the ChArMEx domain observed by the ground-based lidars (Minorca, Barcelona and Lampedusa), a Falcon-20 aircraft flight and three CALIOP tracks, agrees very well with the model simulation of the three major sources considered in this work: Canadian and Colorado fires, a dust storm from western US and the contribution of Saharan dust streamers advected from the North Atlantic trade wind region into the westerlies region. Four aerosol types were identified using the optical properties of the observed aerosol layers (aerosol depolarization ratio, lidar ratio) and the transport model analysis of the contribution of each aerosol source: (i) pure BB layer, (ii) weakly dusty BB, (iii) significant mixture of BB and dust transported from the trade wind region, and (iv) the outflow of Saharan dust by the subtropical jet and not mixed with BB aerosol. The contribution of the Canadian fires is the major aerosol source during this episode while mixing of dust and BB is only significant at an altitude above 5 km. The mixing corresponds to a 20-30 % dust contribution in the total aerosol backscatter. The comparison with the MODIS aerosol optical depth horizontal distribution during this episode over the western Mediterranean Sea shows that the Canadian fire contributions were as large as the direct northward dust outflow

  9. Aerosol effect on the warm rain formation process: Satellite observations and modeling

    NASA Astrophysics Data System (ADS)

    Suzuki, Kentaroh; Stephens, Graeme L.; Lebsock, Matthew D.

    2013-01-01

    This study demonstrates how aerosols influence the liquid precipitation formation process. This demonstration is provided by the combined use of satellite observations and global high-resolution model simulations. Methodologies developed to examine the warm cloud microphysical processes are applied to both multi-sensor satellite observations and aerosol-coupled global cloud-resolving model (GCRM) results to illustrate how the warm rain formation process is modulated under different aerosol conditions. The observational analysis exhibits process-scale signatures of rain suppression due to increased aerosols, providing observational evidence of the aerosol influence on precipitation. By contrast, the corresponding statistics obtained from the model show a much faster rain formation even for polluted aerosol conditions and much weaker reduction of precipitation in response to aerosol increase. It is then shown that this reduced sensitivity points to a fundamental model bias in the warm rain formation process that in turn biases the influence of aerosol on precipitation. A method of improving the model bias is introduced in the context of a simplified single-column model (SCM) that represents the cloud-to-rain water conversion process in a manner similar to the original GCRM. Sensitivity experiments performed by modifying the model assumptions in the SCM and their comparisons to satellite statistics both suggest that the auto-conversion scheme has a critical role in determining the precipitation response to aerosol perturbations and also provide a novel way of constraining key parameters in the auto-conversion schemes of global models.

  10. In situ observations of aerosol and chlorine monoxide after the 1991 eruption of Mount Pinatubo - Effect of reactions on sulfate aerosol

    NASA Technical Reports Server (NTRS)

    Wilson, J. C.; Jonsson, H. H.; Brock, C. A.; Toohey, D. W.; Avallone, L. M.; Baumgardner, D.; Dye, J. E.; Poole, L. R.; Woods, D. C.; Decoursey, R. J.

    1993-01-01

    Highly resolved aerosol size distributions measured from high-altitude aircraft can be used to describe the effect of the 1991 eruption of Mount Pinatubo on the stratospheric aerosol. In some air masses, aerosol mass mixing ratios increased by factors exceeding 100 and aerosol surface area concentrations increased by factors of 30 or more. Increases in aerosol surface area concentration were accompanied by increases in chlorine monoxide at mid-latitudes when confounding factors were controlled. This observation supports the assertion that reactions occurring on the aerosol can increase the fraction of stratospheric chlorine that occurs in ozone-destroying forms.

  11. Observation of low single scattering albedo of aerosols in the downwind of the East Asian desert and urban areas during the inflow of dust aerosols

    NASA Astrophysics Data System (ADS)

    Khatri, Pradeep; Takamura, Tamio; Shimizu, Atsushi; Sugimoto, Nobuo

    2014-01-01

    We analyzed data observed at Fukue-jima (32.752°N, 128.682°E), the downwind of the East Asian desert and urban areas, during the spring season (March-April) of 2008-2011 aiming to understand the light-absorption capacity of Asian dust aerosols, which is a topic of controversy. We observed the decreasing tendency of single-scattering albedo (SSA) with the decrease of Ångström exponent and the increase of the ratio of dust aerosol optical thickness to total aerosol optical thickness, suggesting the important role of coarse-mode dust aerosols on observed low SSAs. The observational data further indicated that the low SSAs during strong dust events were less likely due to the effect of only strong light-absorbing carbonaceous aerosols, such as black carbon (BC), indicating the association of aerosol size distribution on modulating SSA. Such observational results are justified by numerical calculations showing that aerosol size distribution can be the key factor on modulating SSA even without any change in relative amount of light-absorbing aerosol as well as total aerosol optical thickness. Therefore, the observed low SSAs in the downwind regions during dust events could be partially due to the dominance of coarse-mode aerosols over fine-mode aerosols, which are usual in dust events, along with the effect of mixed light-absorbing aerosols. The study further suggests that such effect of aerosol size distribution on SSA can be one of the important reasons for the low SSAs of dust aerosols in the source region as reported by some studies, if coarse-mode aerosols dominate fine-mode aerosols.

  12. The missing aerosol response in twentieth-century mid-latitude precipitation observations

    NASA Astrophysics Data System (ADS)

    Osborne, Joe M.; Lambert, F. Hugo

    2014-05-01

    Regional temperature change over the twentieth century has been strongly influenced by aerosol forcing. The aerosol effect is also expected to be pronounced on regional precipitation change. Changes in historical precipitation--for the global mean and land mean of certain regions--should be more sensitive to spatially heterogeneous aerosol forcing than greenhouse gas forcing. Here, we investigate whether regional precipitation and temperature respond predictably to a significant strengthening in mid-twentieth-century Northern Hemisphere mid-latitude (NHML) aerosol forcing. Using the latest climate model experiments, we find that observed regional temperature changes and observed Northern Hemisphere tropical land precipitation changes are consistent with the IPCC Fifth Assessment Report aerosol forcing estimate, but observed NHML land precipitation changes show little evidence of an aerosol response. This may be a result of changes in precipitation measurement practice that increased observed precipitation totals at the same time that aerosol forcing was expected to reduce them. Investigating this inconsistency, we calculate the required increase in early-twentieth-century observed NHML land precipitation to bring this result in line with aerosol forcing. Biases greater than this calculated correction have been identified in countries within the NHML region previously, notably the former Soviet Union. These observations are frequently used as a metric for the quality of model-simulated precipitation. More homogeneity studies would be of huge benefit.

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

    NASA Astrophysics Data System (ADS)

    Gasteiger, Josef; Wiegner, Matthias

    2013-05-01

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

  14. Patterns in atmospheric carbonaceous aerosols in China: emission estimates and observed concentrations

    NASA Astrophysics Data System (ADS)

    Cui, H.; Mao, P.; Zhao, Y.; Nielsen, C. P.; Zhang, J.

    2015-03-01

    China is experiencing severe carbonaceous aerosol pollution driven mainly by large emissions resulting from intensive use of solid fuels. To gain a better understanding of the levels and trends of carbonaceous aerosol emissions and the resulting ambient concentrations at the national scale, we update an emission inventory of anthropogenic organic carbon (OC) and elemental carbon (EC) and employ existing observational studies to analyze characteristics of these aerosols including temporal, spatial, and size distributions, and the levels and shares of secondary organic carbon (SOC) in total OC. We further use ground observations to test the levels and inter-annual trends of the calculated national and provincial emissions of carbonaceous aerosols, and propose possible improvements in emission estimation for the future. The national OC emissions are estimated to have increased 29% from 2000 (2127 Gg) to 2012 (2749 Gg) and EC by 37% (from 1356 to 1857 Gg). The residential, industrial, and transportation sectors contributed an estimated 76 ± 2, 19 ± 2 and 5 ± 1% of the total emissions of OC, respectively, and 52 ± 3, 32 ± 2 and 16 ± 2% of EC. Updated emission factors based on the most recent local field measurements, particularly for biofuel stoves, lead to considerably lower emissions of OC compared to previous inventories. Compiling observational data across the country, higher concentrations of OC and EC are found in northern and inland cities, while larger OC/EC and SOC/OC ratios are found in southern cities, due to the joint effects of primary emissions and meteorology. Higher SOC/OC ratios are estimated at rural and remote sites compared to urban ones, attributed to more emissions of OC from biofuel use, more biogenic emissions of volatile organic compound (VOC) precursors to SOC, and/or transport of aged aerosols. For most sites, higher concentrations of OC, EC, and SOC are observed in colder seasons, while SOC/OC is reduced, particularly at rural and

  15. Patterns in atmospheric carbonaceous aerosols in China: emission estimates and observed concentrations

    NASA Astrophysics Data System (ADS)

    Cui, H.; Mao, P.; Zhao, Y.; Nielsen, C. P.; Zhang, J.

    2015-08-01

    China is experiencing severe carbonaceous aerosol pollution driven mainly by large emissions resulting from intensive use of solid fuels. To gain a better understanding of the levels and trends of carbonaceous aerosol emissions and the resulting ambient concentrations at the national scale, we update an emission inventory of anthropogenic organic carbon (OC) and elemental carbon (EC) and employ existing observational studies to analyze characteristics of these aerosols including temporal, spatial, and size distributions, and the levels and shares of secondary organic carbon (SOC) in total OC. We further use ground observations to test the levels and inter-annual trends of the calculated national and provincial emissions of carbonaceous aerosols, and propose possible improvements in emission estimation for the future. The national OC emissions are estimated to have increased 29 % from 2000 (2127 Gg) to 2012 (2749 Gg) and EC by 37 % (from 1356 to 1857 Gg). The residential, industrial, and transportation sectors contributed an estimated 74-78, 17-21, and 4-6 % of the total emissions of OC, respectively, and 49-55, 30-34, and 14-18 % of EC. Updated emission factors (EFs) based on the most recent local field measurements, particularly for biofuel stoves, led to considerably lower emissions of OC compared to previous inventories. Compiling observational data across the country, higher concentrations of OC and EC are found in northern and inland cities, while higher OC / EC ratios are found in southern sites, due to the joint effects of primary emissions and meteorology. Higher OC / EC ratios are estimated at rural and remote sites compared to urban ones, attributed to more emissions of OC from biofuel use, more biogenic emissions of volatile organic compound (VOC) precursors to SOC, and/or transport of aged aerosols. For most sites, higher concentrations of OC, EC, and SOC are observed in colder seasons, while SOC / OC is reduced, particularly at rural and remote sites

  16. Observed Holiday Aerosol Reduction and Temperature Cooling over East Asia

    SciTech Connect

    Gong, Daoyi; Wang, Wenshan; Qian, Yun; Bai, Wenbing; Guo, Yuanxi; Mao, Rui

    2014-06-16

    The Spring Festival air pollution in China was investigated using the long-term observations from 2001-2012 over 323 stations. During the Spring Festival with nearly half of urban population leaving the cities for holidays, the particulate matter (PM10) concentration is about 24.5μgm-3 (23%) lower than normal days. Associated with the national-wide burning of firework, the PM10 concentration sharply increases to 123.8μgm-3 at Chinese New Year Day (increment of 35%). Similar to PM10, the SO2 and NO2 decrease from high values in normal days to a holiday minimum with reduction of 23.3% and 30.6%, respectively. The NO2 has no peak in New Year Day because of the different emission source. The night mean and minimum temperature co-vary with PM10. Both nighttime mean and minimum temperature decrease by about 2.1°C during the holidays. And in association with the pollution jump at New Year Day the night temperature simultaneously increase by about 0.89°C. The in-phase co-variations between PM10 and night temperature suggest an overall warming effect of holiday aerosol during winter in China.

  17. Aerosol physicochemical properties and implications for visibility during an intense haze episode during winter in Beijing

    NASA Astrophysics Data System (ADS)

    Wang, Y. H.; Liu, Z. R.; Zhang, J. K.; Hu, B.; Ji, D. S.; Yu, Y. C.; Wang, Y. S.

    2015-03-01

    The evolution of physical, chemical and optical properties of urban aerosol particles was characterized during an extreme haze episode in Beijing, PRC, from 24 through 31 January 2013 based on in situ measurements. The average mass concentrations of PM1, PM2.5 and PM10 were 99 ± 67 μg m-3 (average ± SD), 188 ± 128 μg m-3 and 265 ± 157 μg m-3, respectively. A significant increase in PM1-2.5 fraction was observed during the most heavily polluted period. The average scattering coefficient at 550 nm was 877 ± 624 Mm-1. An increasing relative amount of coarse particles can be deduced from the variations of backscattering ratios, asymmetry parameter and scattering Ångström exponent. Particle number-size distributions between 14 and 2500 nm diameter showed high number concentrations, particularly in the nucleation mode and accumulation mode. Size-resolved chemical composition of submicron aerosol from a high-resolution time-of-flight aerosol mass spectrometer showed that the mass concentrations of organic, sulfate, nitrate, ammonium and chlorine mainly resided on particles between 500 and 800 nm (vacuum diameter), and nitrate and ammonium contributed greatly to particle growth during the heavily polluted day (28 January). Increasing relative humidity and stable synoptic conditions on 28 January combined with heavy pollution on 28 January, leading to enhanced water uptake by the hygroscopic submicron particles and formation of secondary aerosol, which might be the main reasons for the severity of the haze episode. Light-scattering apportionment showed that organic, sulfate, ammonium nitrate and ammonium chloride compounds contributed to light-scattering fractions of 54, 24, 12 and 10%, respectively. This study indicated that the organic component in submicron aerosol played an important role in visibility degradation during the haze episode in Beijing.

  18. Variability of aerosol particle number concentrations observed over the western Pacific in the spring of 2009

    NASA Astrophysics Data System (ADS)

    Takegawa, N.; Moteki, N.; Oshima, N.; Koike, M.; Kita, K.; Shimizu, A.; Sugimoto, N.; Kondo, Y.

    2014-12-01

    Airborne measurements of aerosols were conducted over the western Pacific in the spring of 2009 during the Aerosol Radiative Forcing in East Asia (A-FORCE) aircraft campaign. The A-FORCE flights intensively covered an important vertical-latitudinal range in the outflow region of East Asia (0-9 km altitude; 27°N-38°N). This paper presents the variability of aerosol particle number concentrations obtained by condensation particle counters and a Single-Particle Soot Photometer (SP2), with the focus on those in the free troposphere. The number concentration data include total condensation nuclei with particle diameters (dp) larger than 10 nm (total CN10), PM0.17-CN10 (dp ~10-130 nm), and SP2 black carbon (NBC; dp ~75-850 nm). Large increases in total CN10 that were not associated with NBC were observed in the free troposphere, suggesting influences from new particle formation (NPF). Statistical characteristics of total CN10, PM0.17-CN10, and NBC in the lower troposphere (LT; 0-3 km), middle troposphere (MT; 3-6 km), and upper troposphere (UT; 6-9 km) are investigated. The correlation between total CN10 and NBC, along with the ratio of PM0.17 to total CN10 and carbon monoxide mixing ratio (CO), is used to interpret the observed variability. The median concentrations of total CN10 and PM0.17-CN10 in the UT were higher than those in the MT by a factor of ~1.4 and ~1.6, respectively. We attribute the enhancements of CN10 in the UT to NPF. Possible mechanisms affecting NPF in the free troposphere are discussed.

  19. Evaluation of a size-resolved aerosol model based on satellite and ground observations and its implication on aerosol forcing

    NASA Astrophysics Data System (ADS)

    Ma, Xiaoyan; Yu, Fangqun

    2016-04-01

    The latest AeroCom phase II experiments have showed a large diversity in the simulations of aerosol concentrations, size distribution, vertical profile, and optical properties among 16 detailed global aerosol microphysics models, which contribute to the large uncertainty in the predicted aerosol radiative forcing and possibly induce the distinct climate change in the future. In the last few years, we have developed and improved a global size-resolved aerosol model (Yu and Luo, 2009; Ma et al., 2012; Yu et al., 2012), GEOS-Chem-APM, which is a prognostic multi-type, multi-component, size-resolved aerosol microphysics model, including state-of-the-art nucleation schemes and condensation of low volatile secondary organic compounds from successive oxidation aging. The model is one of 16 global models for AeroCom phase II and participated in a couple of model inter-comparison experiments. In this study, we employed multi-year aerosol optical depth (AOD) data from 2004 to 2012 taken from ground-based Aerosol Robotic Network (AERONET) measurements and Moderate Resolution Imaging Spectroradiometer (MODIS), Multiangle Imaging SpectroRadiometer (MISR) and Sea-viewing Wide Field-of-view Sensor (SeaWiFS) satellite retrievals to evaluate the performance of the GEOS-Chem-APM in predicting aerosol optical depth, including spatial distribution, reginal variation and seasonal variabilities. Compared to the observations, the modelled AOD is overall good over land, but quite low over ocean possibly due to low sea salt emission in the model and/or higher AOD in satellite retrievals, specifically MODIS and MISR. We chose 72 AERONET sites having at least 36 months data available and representative of high spatial domain to compare with the model and satellite data. Comparisons in various representative regions show that the model overall agrees well in the major anthropogenic emission regions, such as Europe, East Asia and North America. Relative to the observations, the modelled AOD is

  20. Mass Spectral Observations of Submicron Aerosol Particles and Production of Secondary Organic Aerosol at an Anthropogenically Influenced Site during the Wet Season of GoAmazon2014

    NASA Astrophysics Data System (ADS)

    de Sá, S. S.; Palm, B. B.; Campuzano Jost, P.; Day, D. A.; Hu, W.; Newburn, M. K.; Ferreira De Brito, J.; Artaxo, P.; Shilling, J. E.; Souza, R. A. F. D.; Manzi, A. O.; Alexander, M. L.; Jimenez, J. L.; Martin, S. T.

    2014-12-01

    As part of GoAmazon2014, a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) was deployed to characterize the composition, size, and spectral markers present in submicron atmospheric aerosol particles at a site downwind of Manaus, Brazil, in the central Amazon basin. The focus was on the influence of biogenic-anthropogenic interactions on the measured aerosol particles, especially as related to the formation of secondary organic aerosol (SOA). Through a combination of meteorology, emissions, and chemistry, the research site was affected by biogenic emissions from the tropical rainforest that were periodically mixed with urban outflow from the Manaus metropolitan area. Results from the first intensive operation period, from 1 February to 31 March 2014, show that for the wet season the PM1 mass concentration had typical values on order of 1 to 2 μg/m3. The organic species were dominant, followed by sulfate. The mass-diameter distribution of the particle population had a prevailing mode between 300 and 400 nm (vacuum aerodynamic diameter, dva), and at times a smaller mode at finer size was also present. Highly oxidized organic material was frequently observed, characterized by a dominant peak at m/z 44. There was a diel trend in the elemental oxygen-to-carbon (O:C) ratio peaking in the afternoon. The analysis of the results aims at delineating the anthropogenic impact on the measurements. Multivariate statistical analysis by positive-matrix factorization (PMF) is applied to the time series of organic particle mass spectra. The factors and their loadings provide information on the relative and time-varying contributions of different sources and processes affecting the organic component of the aerosol particle phase. Relationships between AMS results and measurements from co-located instruments that provide information on anthropogenic and biogenic gas and particle tracers are investigated, toward the goal of improving the understanding of

  1. Photoacoustics of single laser-trapped nanodroplets for the direct observation of nanofocusing in aerosol photokinetics

    NASA Astrophysics Data System (ADS)

    Cremer, Johannes W.; Thaler, Klemens M.; Haisch, Christoph; Signorell, Ruth

    2016-03-01

    Photochemistry taking place in atmospheric aerosol droplets has a significant impact on the Earth's climate. Nanofocusing of electromagnetic radiation inside aerosols plays a crucial role in their absorption behaviour, since the radiation flux inside the droplet strongly affects the activation rate of photochemically active species. However, size-dependent nanofocusing effects in the photokinetics of small aerosols have escaped direct observation due to the inability to measure absorption signatures from single droplets. Here we show that photoacoustic measurements on optically trapped single nanodroplets provide a direct, broadly applicable method to measure absorption with attolitre sensitivity. We demonstrate for a model aerosol that the photolysis is accelerated by an order of magnitude in the sub-micron to micron size range, compared with larger droplets. The versatility of our technique promises broad applicability to absorption studies of aerosol particles, such as atmospheric aerosols where quantitative photokinetic data are critical for climate predictions.

  2. Photoacoustics of single laser-trapped nanodroplets for the direct observation of nanofocusing in aerosol photokinetics.

    PubMed

    Cremer, Johannes W; Thaler, Klemens M; Haisch, Christoph; Signorell, Ruth

    2016-01-01

    Photochemistry taking place in atmospheric aerosol droplets has a significant impact on the Earth's climate. Nanofocusing of electromagnetic radiation inside aerosols plays a crucial role in their absorption behaviour, since the radiation flux inside the droplet strongly affects the activation rate of photochemically active species. However, size-dependent nanofocusing effects in the photokinetics of small aerosols have escaped direct observation due to the inability to measure absorption signatures from single droplets. Here we show that photoacoustic measurements on optically trapped single nanodroplets provide a direct, broadly applicable method to measure absorption with attolitre sensitivity. We demonstrate for a model aerosol that the photolysis is accelerated by an order of magnitude in the sub-micron to micron size range, compared with larger droplets. The versatility of our technique promises broad applicability to absorption studies of aerosol particles, such as atmospheric aerosols where quantitative photokinetic data are critical for climate predictions. PMID:26979973

  3. Satellite Observations of the Effect of Natural and Anthropogenic Aerosols on Clouds

    NASA Technical Reports Server (NTRS)

    Kaufman, Yoram J.

    2006-01-01

    Our knowledge of atmospheric aerosols (smoke, pollution, dust or sea salt particles, small enough to be suspended in the air), their evolution, composition, variability in space and time and interaction with clouds and precipitation is still lacking despite decades of research. Understanding the global aerosol system is critical to quantifying anthropogenic climate change, to determine climate sensitivity from observations and to understand the hydrological cycle. While a single instrument was used to demonstrate 50 years ago that the global CO2 levels are rising, posing threat of global warming, we need an array of satellites and field measurements coupled with chemical transport models to understand the global aerosol system. This complexity of the aerosol problem results from their short lifetime (1 week) and variable chemical composition. A new generation of satellites provides exciting opportunities to measure the global distribution of aerosols, distinguishing natural from anthropogenic aerosol and measuring their interaction with clouds and climate.

  4. New Results from Space and Field Observations on the Aerosol Direct and Indirect Radiative Forcing

    NASA Technical Reports Server (NTRS)

    Kaufman, Yoram J.; Remer, Lorraine; Tanre, Didier; Boucher, Olivier; Chin, Mian; Dubovik, Oleg; Holben, Brent

    2002-01-01

    New space observations from the MODIS instrument on board the Terra satellite and analysis of POLDER data flown on the ADEOS satellite, show in great details the spatial and seasonal variability of the global aerosol system. These spaceborne instruments distinguish fine aerosol from man-made regional pollution and biomass burning from mostly natural coarse dust and sea salt aerosol. E.g. fine regional pollution in and around the Indian sub-continent, Europe and North America; smoke from biomass burning in Southern Africa and Southern America; coarse dust from West Africa and mixed dust pollution and smoke from West and central Africa and East Asia. These regions were also studied extensively in focused field experiments and by the distributed AERONET network. The results generate the first climatologies of the aerosol system, are used to derive the aerosol radiative effects and to estimate the anthropogenic component. The measurements are also used to evaluate each other and constrain aerosol transport models.

  5. Photoacoustics of single laser-trapped nanodroplets for the direct observation of nanofocusing in aerosol photokinetics

    PubMed Central

    Cremer, Johannes W.; Thaler, Klemens M.; Haisch, Christoph; Signorell, Ruth

    2016-01-01

    Photochemistry taking place in atmospheric aerosol droplets has a significant impact on the Earth's climate. Nanofocusing of electromagnetic radiation inside aerosols plays a crucial role in their absorption behaviour, since the radiation flux inside the droplet strongly affects the activation rate of photochemically active species. However, size-dependent nanofocusing effects in the photokinetics of small aerosols have escaped direct observation due to the inability to measure absorption signatures from single droplets. Here we show that photoacoustic measurements on optically trapped single nanodroplets provide a direct, broadly applicable method to measure absorption with attolitre sensitivity. We demonstrate for a model aerosol that the photolysis is accelerated by an order of magnitude in the sub-micron to micron size range, compared with larger droplets. The versatility of our technique promises broad applicability to absorption studies of aerosol particles, such as atmospheric aerosols where quantitative photokinetic data are critical for climate predictions. PMID:26979973

  6. Choosing a 'best' global aerosol model: Can observations constrain parametric uncertainty?

    NASA Astrophysics Data System (ADS)

    Browse, Jo; Reddington, Carly; Pringle, Kirsty; Regayre, Leighton; Lee, Lindsay; Schmidt, Anja; Field, Paul; Carslaw, Kenneth

    2015-04-01

    Anthropogenic aerosol has been shown to contribute to climate change via direct radiative forcing and cloud-aerosol interactions. While the role of aerosol as a climate agent is likely to diminish as CO2 emissions increase, recent studies suggest that uncertainty in modelled aerosol is likely to dominate uncertainty in future forcing projections. Uncertainty in modelled aerosol derives from uncertainty in the representation of emissions and aerosol processes (parametric uncertainty) as well as structural error. Here we utilise Latin hyper-cube sampling methods to produce an ensemble model (composed of 280 runs) of a global model of aerosol processes (GLOMAP) spanning 31 parametric ranges. Using an unprecedented number of observations made available by the GASSP project we have evaluated our ensemble model against a multi-variable (CCN, BC mass, PM2.5) data-set to determine if 'an ideal' aerosol model exists. Ignoring structural errors, optimization of a global model against multiple data-sets to within a factor of 2 is possible, with multiple model runs identified. However, (even regionally) the parametric range of our 'best' model runs is very wide with the same model skill arising from multiple parameter settings. Our results suggest that 'traditional' in-situ measurements are insufficient to constrain parametric uncertainty. Thus, to constrain aerosol in climate models, future evaluations must include process based observations.

  7. Observed emotion frequency versus intensity as predictors of socioemotional maladjustment.

    PubMed

    Hernández, Maciel M; Eisenberg, Nancy; Valiente, Carlos; Spinrad, Tracy L; VanSchyndel, Sarah K; Diaz, Anjolii; Berger, Rebecca H; Silva, Kassondra M; Southworth, Jody; Piña, Armando A

    2015-12-01

    The purpose of this study was to assess whether observed emotional frequency (the proportion of instances an emotion was observed) and intensity (the strength of an emotion when it was observed) uniquely predicted kindergartners' (N = 301) internalizing and externalizing problems. Analyses were tested in a structural equation modeling (SEM) framework with data from multireporters (reports of problem behaviors from teachers and parents) and naturalistic observations of emotion in the fall semester. For observed positive emotion, both frequency and intensity negatively predicted parent- or teacher-reported internalizing symptoms. Anger frequency positively predicted parent- and teacher-reported externalizing symptoms, whereas anger intensity positively predicted parent- and teacher-reported externalizing and parent-reported internalizing symptoms. The findings support the importance of examining both aspects of emotion when predicting maladjustment. PMID:26214568

  8. North Atlantic Aerosol Radiative Effects Based on Satellite Measurements and Aerosol Intensive Properties from TARFOX and ACE-2

    NASA Technical Reports Server (NTRS)

    Bergstrom, Robert W.; Russell, Philip B.

    2000-01-01

    We estimate the impact of North Atlantic aerosols on the net shortwave flux at the tropopause by combining maps of satellite-derived aerosol optical depth (AOD) with model aerosol properties. We exclude African dust, primarily by restricting latitudes to 25-60 N. Aerosol properties were determined via column closure analyses in two recent experiments, TARFOX and ACE 2. The analyses use in situ measurements of aerosol composition and air- and ship-borne sunphotometer measurements of AOD spectra. The resulting aerosol model yields computed flux sensitivities (dFlux/dAOD) that agree with measurements by airborne flux radiometers in TARFOX. It has a midvisible single-scattering albedo of 0.9, which is in the range obtained from in situ measurements of aerosol scattering and absorption in both TARFOX and ACE 2. Combining seasonal maps of AVHRR-derived midvisible AOD with the aerosol model yields maps of 24-hour average net radiative flux changes at the tropopause. For cloud-free conditions, results range from -9 W/sq m near the eastern US coastline in the summer to -1 W/sq m in the mid-Atlantic during winter; the regional annual average is -3.5 W/sq m. Using a non- absorbing aerosol model increases these values by about 30%. We estimate the effect of clouds using ISCCP cloud-fraction maps. Because ISCCP midlatitude North Atlantic cloud fractions are relatively large, they greatly reduce the computed aerosol-induced flux changes. For example, the regional annual average decreases from -3.5 W/sq m to -0.8 W/sq m. We compare results to previous model calculations for a variety of aerosol types.

  9. Secondary Aerosol Formation in the planetary boundary layer observed by aerosol mass spectrometry on a Zeppelin NT

    NASA Astrophysics Data System (ADS)

    Rubach, Florian; Trimborn, Achim; Mentel, Thomas; Wahner, Andreas; Zeppelin Pegasos-Team 2012

    2014-05-01

    The airship Zeppelin NT is an airborne platform capable of flying at low speed throughout the entire planetary boundary layer (PBL). In combination with the high scientific payload of more than 1 ton, the Zeppelin is an ideal platform to study regional processes in the lowest layers of the atmosphere with high spatial resolution. Atmospheric aerosol as a medium long lived tracer substance is of particular interest due to its influence on the global radiation budget. Due its lifetime of up to several days secondaray aerosol at a certain location can result from local production or from transport processes. For aerosol measurements on a Zeppelin, a High-Resolution Time-of-Flight Aerosol Mass spectrometer (DeCarlo et al, 2006) was adapted to the requirements posed by an airborne platform. A weight reduction of over 20 % compared to the commercial instrument was achieved, while space occupation and footprint were each reduced by over 25 %. Within the PEGASOS project, the instrument was part of 10 measurement flight days over the course of seven weeks. Three flights were starting from Rotterdam, NL, seven flights were starting from Ozzano in the Po Valley, IT. Flight patterns included vertical profiles to study the dynamics of the PBL and cross sections through regions of interest to shed light on local production and transport processes. Analysis of data from transects between the Apennin and San Pietro Capofiume in terms of "residence time of air masses in the Po valley" indicates that aerosol nitrate has only local sources while aerosol sulfate is dominated by transport. The organic aerosol component has significant contributions of both processes. The local prodcution yields are commensurable with imultaneously observed precursor concentrations and oxidant levels. The PEGASOS project is funded by the European Commission under the Framework Programme 7 (FP7-ENV-2010-265148). DeCarlo, P.F. et al (2006), Anal. Chem., 78, 8281-8289.

  10. Large-Scale Covariability Between Aerosol and Precipitation Over the 7-SEAS Region: Observations and Simulations

    NASA Technical Reports Server (NTRS)

    Huang, Jingfeng; Hsu, N. Christina; Tsay, Si-Chee; Zhang, Chidong; Jeong, Myeong Jae; Gautam, Ritesh; Bettenhausen, Corey; Sayer, Andrew M.; Hansell, Richard A.; Liu, Xiaohong; Jiang, Jonathan H.

    2012-01-01

    One of the seven scientific areas of interests of the 7-SEAS field campaign is to evaluate the impact of aerosol on cloud and precipitation (http://7-seas.gsfc.nasa.gov). However, large-scale covariability between aerosol, cloud and precipitation is complicated not only by ambient environment and a variety of aerosol effects, but also by effects from rain washout and climate factors. This study characterizes large-scale aerosol-cloud-precipitation covariability through synergy of long-term multi ]sensor satellite observations with model simulations over the 7-SEAS region [10S-30N, 95E-130E]. Results show that climate factors such as ENSO significantly modulate aerosol and precipitation over the region simultaneously. After removal of climate factor effects, aerosol and precipitation are significantly anti-correlated over the southern part of the region, where high aerosols loading is associated with overall reduced total precipitation with intensified rain rates and decreased rain frequency, decreased tropospheric latent heating, suppressed cloud top height and increased outgoing longwave radiation, enhanced clear-sky shortwave TOA flux but reduced all-sky shortwave TOA flux in deep convective regimes; but such covariability becomes less notable over the northern counterpart of the region where low ]level stratus are found. Using CO as a proxy of biomass burning aerosols to minimize the washout effect, large-scale covariability between CO and precipitation was also investigated and similar large-scale covariability observed. Model simulations with NCAR CAM5 were found to show similar effects to observations in the spatio-temporal patterns. Results from both observations and simulations are valuable for improving our understanding of this region's meteorological system and the roles of aerosol within it. Key words: aerosol; precipitation; large-scale covariability; aerosol effects; washout; climate factors; 7- SEAS; CO; CAM5

  11. What we can Learn About Aerosols from EOS-MISR Multi-Angle Remote Sensing Observations

    NASA Technical Reports Server (NTRS)

    Kahn, Ralph

    2000-01-01

    Multiangle, multispectral remote sensing observations, such as those anticipated from the Earth Observing System (EOS) Multiangle Imaging SpectroRadiometer (MISR), promise to significantly improve our ability to constrain aerosol properties from space. Recent advances in modeling the Earth's climate have brought us to a point where the contributions made by aerosols to the global radiation budget noticeably affect the results. Knowledge of both aerosol optical depth and the microphysical properties of particles is needed to adequately model aerosol effects. This talk explores the ability of multiangle, multi-spectral remote sensing observations anticipated from the EOS MISR instrument, to retrieve aerosol optical depth and information about mixes of particle types, globally, at 17.6 km spatial resolution. The instrument is scheduled for launch into a 10:30 AM, sun-synchronous polar orbit in 1999.

  12. Airborne Observations of Aerosol Emissions from F-16 Aircraft

    NASA Technical Reports Server (NTRS)

    Anderson, B. E.; Cofer, W. R.; McDougal, D. S.

    1999-01-01

    We presented results from the SASS Near-Field Interactions Flight (SNIF-III) Experiment which was conducted during May and June 1997 in collaboration with the Vermont and New Jersey Air National Guard Units. The project objectives were to quantify the fraction of fuel sulfur converted to S(VI) species by jet engines and to gain a better understanding of particle formation and growth processes within aircraft wakes. Size and volatility segregated aerosol measurements along with sulfur species measurements were recorded in the exhaust of F-16 aircraft equipped with F-100 engines burning fuels with a range of fuel S concentrations at different altitudes and engine power settings. A total of 10 missions were flown in which F-16 exhaust plumes were sampled by an instrumented T-39 Sabreliner aircraft. On six of the flights, measurements were obtained behind the same two aircraft, one burning standard JP-8 fuel and the other either approximately 28 ppm or 1100 ppm S fuel or an equal mixture of the two (approximately 560 ppm S). A pair of flights was conducted for each fuel mixture, one at 30,000 ft altitude and the other starting at 35,000 ft and climbing to higher altitudes if contrail conditions were not encountered at the initial flight level. In each flight, the F-16s were operated at two power settings, approx. 80% and full military power. Exhaust emissions were sampled behind both aircraft at each flight level, power setting, and fuel S concentration at an initial aircraft separation of 30 m, gradually widening to about 3 km. Analyses of the aerosol data in the cases where fuel S was varied suggest results were consistent with observations from project SUCCESS, i.e., a significant fraction of the fuel S was oxidized to form S(VI) species and volatile particle emission indices (EIs) in comparably aged plumes exhibited a nonlinear dependence upon the fuel S concentration. For the high sulfur fuel, volatile particle EIs in 10-second-old-plumes were 2 to 3 x 10 (exp 17

  13. Characterization of aerosols in East Asia with the Asian Dust and Aerosol Lidar Observation Network (AD-Net)

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

    Continuous observations of aerosols are being conducted with the Asian Dust and aerosol lidar observation Network (AD-Net). Currently, two-wavelength (1064 nm and 532 nm) polarization-sensitive (532 nm) lidars are operated at 20 stations in East Asia. At the primary stations (6 stations), nitrogen vibrational Raman scattering is also measured to obtain the extinction coefficient at 532 nm. Recently, continuous observations with a three-wavelength (1064 nm, 532 nm and 355 nm) lidar having a high-spectral-resolution receiver at 532 nm and a Raman receiver at 355 nm and polarization-sensitive receivers at 532 nm and 355 nm) was started in Tsukuba. Also, continuous observations with multi-wavelength Raman lidars are being prepared in Fukuoka, Okinawa Hedo, and Toyama. A data analysis method for deriving distributions of aerosol components (weak absorption fine (such as sulfate), weak absorption coarse (sea salt), strong absorption fine (black carbon), non-spherical (dust)) has been developed for these multi-parameter lidars. Major subjects of the current studies with AD-Net include data assimilation of multi-parameter lidars, mixing states of Asian dust with air pollution particulate matter, and validation of EarthCARE ATLID based on the aerosol component analysis method.

  14. Long range transport and mixing of aerosol sources during the 2013 North American biomass burning episode: analysis of multiple lidar observations in the Western Mediterranean basin

    NASA Astrophysics Data System (ADS)

    Ancellet, G.; Pelon, J.; Totems, J.; Chazette, P.; Bazureau, A.; Sicard, M.; Di Iorio, T.; Dulac, F.; Mallet, M.

    2015-11-01

    Long range transport of biomass burning (BB) aerosols between North America and the Mediterranean region took place in June 2013. A large number of ground based and airborne lidar measurements were deployed in the Western Mediterranean during the Chemistry-AeRosol Mediterranean EXperiment (ChArMEx) intensive observation period. A detailed analysis of the potential North American aerosol sources is conducted including the assessment of their transport to Europe using forward simulations of the FLEXPART Lagrangian particle dispersion model initialized using satellite observations by MODIS and CALIOP. The three dimensional structure of the aerosol distribution in the ChArMEx domain observed by the ground-based lidars (Menorca, Barcelona and Lampedusa), a Falcon-20 aircraft flight and three CALIOP tracks, agree very well with the model simulation of the three major sources considered in this work: Canadian and Colorado fires, a dust storm from Western US and the contribution of Saharan dust streamers advected from the North Atlantic trade wind region into the Westerlies region. Four aerosol types were identified using the optical properties of the observed aerosol layers (aerosol depolarization ratio, lidar ratio) and the transport model analysis of the contribution of each aerosol source: (I) pure BB layer, (II) weakly dusty BB, (III) significant mixture of BB and dust transported from the trade wind region (IV) the outflow of Saharan dust by the subtropical jet and not mixed with BB aerosol. The contribution of the Canadian fires is the major aerosol source during this episode while mixing of dust and BB is only significant at altitude above 5 km. The mixing corresponds to a 20-30 % dust contribution in the total aerosol backscatter. The comparison with the MODIS AOD horizontal distribution during this episode over the Western Mediterranean sea shows that the Canadian fires contribution were as large as the direct northward dust outflow from Sahara.

  15. Ultraviolet dust aerosol properties as observed by MARCI

    NASA Astrophysics Data System (ADS)

    Wolff, Michael J.; Todd Clancy, R.; Goguen, Jay D.; Malin, Michael C.; Cantor, Bruce A.

    2010-07-01

    Observations by the Mars Color Imager (MARCI) on board the Mars Reconnaissance Orbiter (MRO) in two ultraviolet (UV, Bands 6 and 7; 258 nm, and 320 nm, respectively) and one visible (Band 1, 436 nm) channels of the 2007 planet encircling dust storm are combined with those made by the two Mars Exploration Rovers (MERs) to better characterize the single scattering albedo (ω0) of martian dust aerosols. Exploiting the low contrast of the surface in the UV (and blue) as well as the reduced importance of surface reflectance under very dusty conditions, we utilize the sampling of photometric angles by the MARCI cross-track geometry to synthesize an analog of the classical Emergence Phase Function (EPF). This so-called "pseudo-EPF", used in conjunction with the "ground-truth" measurements provided by the MERs, is able to effectively isolate the effects of the dust ω0. The motivation for this approach is the elimination of a significant portion of the type of uncertainty involved in many previous radiative transfer analyses. Furthermore, we produce a self-consistent set of complex refractive indices (m=n+ik) through our use of an explicit microphysical representation of the aerosol scattering properties. Because of uncertainty in the exact size of the dust particles during the epoch of the observations, we consider two effective particle radii (reff) to cover the range anticipated from the literature: 1.6 and 1.8 μm. The resulting set of model-data comparisons, ω0, and m are presented along with an assessment of potential sources of error and uncertainty. Analysis of the Band 1 results is limited to ω0 as a "proof-of-concept" for our approach through a comparison to contemporaneous CRISM EPF results at 440 nm. The derived ω0 are: assuming reff=1.6μm-0.619-0.626,0.648, and 0.765, for Bands 6, 7, and 1, respectively; for reff=1.8μm-0.625-0.635,0.653,0.769, for the same band order. For either reff case, the total estimated error is 0.022, 0.019, and 0.010, again for

  16. Three-dimensional structure of aerosol in China: A perspective from multi-satellite observations

    NASA Astrophysics Data System (ADS)

    Guo, Jianping; Liu, Huan; Wang, Fu; Huang, Jingfeng; Xia, Feng; Lou, Mengyun; Wu, Yerong; Jiang, Jonathan H.; Xie, Tao; Zhaxi, Yangzong; Yung, Yuk L.

    2016-09-01

    Using eight years (2006-2014) of passive (MODIS/Aqua and OMI/Aura) and active (CALIOP/CALIPSO) satellite measurements of aerosols, we yield a three-dimensional (3D) distribution of the frequency of occurrence (FoO) of aerosols over China. As an indicator of the vertical heterogeneity of aerosol layers detected by CALIOP, two types of Most Probable Height (MPH), including MPH_FoO and MPH_AOD, are deduced. The FoO of "Total Aerosol" reveals significant geographical dependence. Eastern China showed much stronger aerosol FoD than northwestern China. The FoO vertical structures of aerosol layer are strongly dependent on altitudes. Among the eight typical ROIs analyzed, aerosol layers over the Gobi Desert have the largest occurrence probability located at an altitude as high as 2.83 km, as compared to 1.26 km over Beijing-Tianjin-Hebei. The diurnal variation (nighttime-daytime) in MPH_AOD varies from an altitude as low as 0.07 km over the Sichuan basin to 0.27 km over the Gobi Desert, whereas the magnitude of the diurnal variation in terms of MPH_AOD is six times as large as the MPH_FoO, mostly attributable to the day/night lidar SNR difference. Also, the 3D distribution of dust and smoke aerosols was presented. The multi-sensor synergized 3D observations of dust aerosols, frequently observed in the zonal belt of 38°N-45°N, is markedly different from that of smoke aerosols that are predominantly located in the eastern and southern parts. The 3D FoO distribution of dust indicates a west-to-east passageway of dust originating from the westernmost Taklimakan Desert all the way to North China Plain (NCP). The findings from the multi-sensor synergetic observations greatly improved our understanding on the long-range aerosol dispersion, transport and passageway over China.

  17. Characterization of smoke aerosols over the Indochina Peninsula from multi-platform satellite observations

    NASA Astrophysics Data System (ADS)

    Jeong, M. J.; Hsu, N. Y. C.; Lee, J.; Sayer, A. M.; Bettenhausen, C.; Huang, J.

    2015-12-01

    Multi-faceted near-simultaneous observations from the sensors aboard multiple satellite platforms, so called the A-Train, are utilized to characterize the spatial distributions and the optical properties of smoke aerosols over the Indochina Peninsula. Observations from the A-Train sensors, especially, MODerate resolution Imaging Spectroradiometer (MODIS), Ozone Monitoring Instrument (OMI), and Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP), are synthesized to retrieve single-scattering albedo (SSA) and effective aerosol layer height (ALH) of BBS aerosols in the region. The retrieval algorithm extracts the absorption and height information about smoke aerosols, which is lumped into ultraviolet spectra at the top of the atmosphere, by taking the most reliable information contents that each satellite measurement can deliver. The results of retrieved SSA and ALH showed reasonable agreements with in-situ measurements, AEROsol Robotic NETwork (AERONET) data, and lidar-based observations. The uncertainty and sensitivity of the retrieval algorithm are also presented. The retrieved quantities are then used together with other satellite datasets to characterize the three-dimensional distributions of smoke aerosols over the Indochina Peninsular during the boreal spring time. Given the frequent horizontal collocations of smoke and clouds in the region, implication of smoke vertical distributions for long-range transports is also discussed. The results of this study are anticipated to advance our understanding on the climatic impacts of the smoke aerosols in the region.

  18. 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.

  19. Stratospheric aerosol increase after eruption of Pinatubo observed with lidar and aureolemeter

    NASA Technical Reports Server (NTRS)

    Hayashida, Sachiko; Sasano, Yasuhiro; Nakane, Hideaki; Matsui, Ichiro; Hayasaka, Tadahiro

    1994-01-01

    An increase in the amount of stratospheric aerosol due to the Pinatubo eruption (June 12-15, 1991, 15.14 deg N, 120.35 deg E) was observed from the end of June, 1991 by a lidar in NIES (National Institute for Environmental Studies), Tsukuba (36.0 deg N, 140.1 deg E). After large fluctuations in summer of 1991, the amount of the aerosols increased in mid-September as a result of enhanced transportation from the subtropical region. In autumn and winter of 1991, dense aerosol layers were continuously observed. Aureolemeter (scanning spectral radiometer) measurements were also carried out with lidar measurements and columnar size distribution of stratospheric aerosols was estimated for some cases. Collaborative measurements with the lidar and aureolemeter provided some information on height distribution of the surface area of aerosols in late 1991.

  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. Signatures of semi-direct radiative forcing by absorbing aerosols in satellite observations and models

    NASA Astrophysics Data System (ADS)

    Wilcox, E. M.; Hosseinpour, F.; Colarco, P. R.

    2014-12-01

    Semi-direct radiative forcing of climate occurs when interactions between aerosols and radiative fluxes in the atmosphere yield a dynamical response in clouds. Semi-direct forcing is typically thought to be a positive radiative forcing whereby soot and biomass burning aerosols absorb sunlight and burn-off clouds. However, a negative semi-direct forcing is suspected in at least two regimes, the summertime Southeast Atlantic Ocean and the wintertime North Indian Ocean, where the heating profile by aerosol absorption by solar radiation is elevated above the elevation of the low clouds. Here we use a combination of satellite data and a model simulation to further characterize the signature of semi-direct radiative forcing in these two locations and elsewhere on the globe. We apply CERES albedos, Calipso profiles of aerosol extinction and cloud-top altitude, and a simulation with the Goddard Earth Observing System Model version 5 (GEOS-5) Earth system model with meteorology constrained by MERRA and an assimilation of MODIS AOT (MERRAero). to quantify the vertical heating profile by aerosols under clear and cloudy skies. We seek to determine: (1) where aerosol heating by soot and biomass burning aerosol is occurring; (2) where vertically in the column the heating is occurring relative to the observed level of low cloud development; and (3) whether the variations of albedo with aerosol forcing suggest a positive, negative, or inconclusive semi-direct radiative forcing.

  2. Simultaneous observations of aerosols, clouds, and radiometric fluxes using light-weight autonomous UAVs

    NASA Astrophysics Data System (ADS)

    Roberts, G.; Ramanathan, V.; Corrigan, C.; Ramana, M.; Nguyen, H.

    2006-12-01

    The Maldives Air Campaign (MAC) demonstrated a novel application of stacked autonomous unmanned aerial vehicles (AUAVs) for atmospheric science research; see abstract by Ramanathan et al. in this session. Simultaneous observations from three AUAVs of aerosols, clouds and radiometric fluxes provide insight into aerosol-cloud interactions and subsequent effects on cloud radiative properties. Ground-based measurements of cloud condensation nuclei (CCN) also quantify the cloud-nucleating ability of the boundary layer aerosols. During the experiment, long-range transport of aerosols from the Arabian Peninsula and India was observed and its impact of cloud physical and radiometric properties has been detected. To accomplish this campaign, aerosol, cloud, radiometric instruments, and an integrated data acquisition system have been miniaturized with a total payload weight and power less than 5 kg and 50 W, respectively. The AUAV payloads are mission-specific and outfitted to perform a defined set of measurements depending on the scientific goals. These measurements include aerosol concentration, aerosol size distribution, aerosol absorption, cloud drop concentration and size distribution, solar radiation fluxes (visible and broadband), atmospheric turbulence, temperature, pressure, and relative humidity. The data collected during the MAC campaign has been validated using standard calibration routines in conjunction with comparisons to ground- based instruments in both laboratory and in situ (in aircraft) settings. All instruments have been thoroughly tested and calibrated prior to deployment.

  3. 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.

  4. Comparison of simulated and observed aerosol optical depth

    NASA Astrophysics Data System (ADS)

    Laulainen, Nels; Ghan, Steven; Easter, Richard; Zaveri, Rahul

    2000-08-01

    A variety of measurements have been used to evaluate the treatment of aerosol radiative properties and radiative impacts of aerosols simulated by the Model for Integrated Research on Atmospheric Global Exchanges (MIRAGE). This paper focuses on comparisons of simulated and measured aerosol optical depth (AOD). When the analyzed relative humidity is used to calculate aerosol water uptake in MIRAGE, the simulated AOD agrees with most surface measurements after cloudy conditions are filtered out and differences between model and station elevations are accounted for. Simulated AODs are low over sites in Brazil during the biomass burning season and over sites in central Canada during the wildfire season, which can be attributed to limitations in the organic and black carbon emissions data used by MIRAGE. The simulated AODs are mostly within a factor of two of satellite estimates, but MIRAGE simulates excessively high AODs off the east coast of the US and China, and too little dust off the coast of West Africa and in the Arabian Sea.

  5. OMI NO2 and aerosol observations during the DANDELIONS campaign

    NASA Astrophysics Data System (ADS)

    Brinksma, E.; Wagner, T.; Richter, A.; van Roozendael, M.; Swart, D.; de Leeuw, G.; Curier, L.; Berkhout, S.; Veefkind, P.; Levelt, P.

    2005-12-01

    Within the two-year project DANDELIONS (Dutch Aerosol and Nitrogen Dioxide Experiments for vaLIdation of OMI and SCIAMACHY), a 9-week campaign took place. The location was the Cabauw Experimental Site for Atmospheric Research (CESAR, 51N, 5E), which is often subject to considerable tropospheric pollution. The campaign focused on measurements of nitrogen dioxide, atmospheric aerosols, and ozone. Five MAXDOAS instruments and one lidar provided data on the nitrogen dioxide total and tropospheric columns, and profiles (0 - 2.5 km). These were intercompared, and also compared to OMI and SCIAMACHY overpass data. The homogeneity of the tropospheric field was studied. A range of permanent aerosol instrumentation, including sun photometers, an aethalometer, nephelometer, boundary layer lidar and radio sonde profiles and MAX DOASes, was used to provide correlative data for OMI and AATSR aerosol optical depths. Ozone Brewer, ozone sondes, and MAX DOASes provided information on tropospheric and total ozone, to be compared with OMI and SCIAMACHY results. Preliminary results show that satellite and groundbased data compare well. In our presentation, we will show information on the homogeneity of the tropospheric pollution, both in ground based and from satellite data. We will also discuss the quality of the OMI data.

  6. Estimating the Radiative Forcing of Carbonaceous Aerosols over California based on Satellite and Ground Observations

    SciTech Connect

    Xu, Yangyang; Bahadur, R.; Zhao, Chun; Leung, Lai-Yung R.

    2013-10-04

    Carbonaceous aerosols have the potential to impact climate both through directly absorbing incoming solar radiation, and by indirectly affecting the cloud layer. To quantify this impact recent modeling studies have made great efforts to simulate both the spatial and temporal distribution of carbonaceous aerosols and their associated radiative forcing. This study makes the first observationally constrained assessment of the direct radiative forcing of carbonaceous aerosols at a regional scale over California. By exploiting multiple observations (including ground sites and satellites), we constructed the distribution of aerosol optical depths and aerosol absorption optical depths over California for a ten-year period (2000-2010). The total solar absorption was then partitioned into contributions from elemental carbon (EC), organic carbon (OC) and dust aerosols using a newly developed scheme. Aerosol absorption optical depth due to carbonaceous aerosols (EC and OC) at 440 nm is 50%-200% larger than natural dust, with EC contributing the bulk (70%-90%). Observationally constrained EC absorption agrees reasonably well with estimates from regional transport models, but the model underestimates the OC AAOD by at least 50%. We estimate that the TOA warming from carbonaceous aerosols is 0.7 W/m2 and the TOA forcing due to OC is close to zero. The atmospheric heating of carbonaceous aerosols is 2.2-2.9 W/m2, of which EC contributed about 80-90%. The atmospheric heating due to OC is estimated to be 0.1 to 0.4 W/m2, larger than model simulations. The surface brightening due to EC reduction over the last two decades is estimated to be 1.5-3.5 W/m2.

  7. Observed correlations between aerosol and cloud properties in an Indian Ocean trade cumulus regime

    NASA Astrophysics Data System (ADS)

    Pistone, Kristina; Praveen, Puppala S.; Thomas, Rick M.; Ramanathan, Veerabhadran; Wilcox, Eric M.; Bender, Frida A.-M.

    2016-04-01

    There are many contributing factors which determine the micro- and macrophysical properties of clouds, including atmospheric vertical structure, dominant meteorological conditions, and aerosol concentration, all of which may be coupled to one another. In the quest to determine aerosol effects on clouds, these potential relationships must be understood. Here we describe several observed correlations between aerosol conditions and cloud and atmospheric properties in the Indian Ocean winter monsoon season.In the CARDEX (Cloud, Aerosol, Radiative forcing, Dynamics EXperiment) field campaign conducted in February and March 2012 in the northern Indian Ocean, continuous measurements were made of atmospheric precipitable water vapor (PWV) and the liquid water path (LWP) of trade cumulus clouds, concurrent with measurements of water vapor flux, cloud and aerosol vertical profiles, meteorological data, and surface and total-column aerosol from instrumentation at a ground observatory and on small unmanned aircraft. We present observations which indicate a positive correlation between aerosol and cloud LWP only when considering cases with low atmospheric water vapor (PWV < 40 kg m-2), a criterion which acts to filter the data to control for the natural meteorological variability in the region.We then use the aircraft and ground-based measurements to explore possible mechanisms behind this observed aerosol-LWP correlation. The increase in cloud liquid water is found to coincide with a lowering of the cloud base, which is itself attributable to increased boundary layer humidity in polluted conditions. High pollution is found to correlate with both higher temperatures and higher humidity measured throughout the boundary layer. A large-scale analysis, using satellite observations and meteorological reanalysis, corroborates these covariations: high-pollution cases are shown to originate as a highly polluted boundary layer air mass approaching the observatory from a northwesterly

  8. 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.

  9. Cloud and Aerosol Interaction Observed in SKYNET Hefei Site in China

    NASA Astrophysics Data System (ADS)

    Wang, Yingjian; Sun, Lu; Liu, Dong; Wang, Zhien; Wang, Zhenzhu; Xie, Chenbo

    2016-06-01

    The interaction relationship between cloud and aerosol is studied via their optical depth and cloud effective radius based on ground-based remote sensors. By attenuated backscatter obtained by lidar the optical depth of cloud and aerosol is retrieved. Combing with liquid water path observed by microwave radiometer, the cloud number concentration and cloud effective radius is also retrieved based on the adiabatic hypothesis Cases studies shows that during the stable stratocumulus with interval precipitation period and aerosol with vertical motion, the cloud effective radius shows both negative and positive relationship with aerosol optical depth. It may be due to the difference of liquid water path of the cloud properties and shows complex interaction with aerosol.

  10. AEROSOL Characterization in SW Asia from long-term AERONET Observations

    NASA Astrophysics Data System (ADS)

    Holben, B. N.

    2005-12-01

    The Arabian Gulf is a focus of aerosol sources and transport in Southwest Asia owing to arid landscapes modified by land degradation, a highly developed fossil fuel industry and the unique meteorology of the region. The aerosol properties were well characterized in the gulf during the UAE2 campaign but their impact on the greater South and Southwest Asia aerosol environment is not well known. The AERONET program has a well established network in the gulf region with a growing distribution in SW Asia including India, Israel, Chad, and SE Africa and Indian Ocean island sites. This presentation will compare the UAE2 campaign and longer term gulf region aerosol characterizations from AERONET to the wider subcontinental and oceanic aerosol properties measured by AERONET over the last decade. These long-term point observations will be supported by backtrajectories and selected MODIS and MISR data since 2001.

  11. Longwave Radiative Forcing of Saharan Dust Aerosols Estimated from MODIS, MISR and CERES Observations on Terra

    NASA Technical Reports Server (NTRS)

    Zhang, Jiang-Long; Christopher, Sundar A.

    2003-01-01

    Using observations from the Multi-angle Imaging Spectroradiometer (MISR), the Moderate Resolution Imaging Spectroradiometer (MODIS), and the Clouds and the Earth's Radiant Energy System (CERES) instruments onboard the Terra satellite; we present a new technique for studying longwave (LW) radiative forcing of dust aerosols over the Saharan desert for cloud-free conditions. The monthly-mean LW forcing for September 2000 is 7 W/sq m and the LW forcing efficiency' (LW(sub eff)) is 15 W/sq m. Using radiative transfer calculations, we also show that the vertical distribution of aerosols and water vapor are critical to the understanding of dust aerosol forcing. Using well calibrated, spatially and temporally collocated data sets, we have combined the strengths of three sensors from the same satellite to quantify the LW radiative forcing, and show that dust aerosols have a "warming" effect over the Saharan desert that will counteract the shortwave "cooling effect" of aerosols.

  12. PSC and volcanic aerosol observations during EASOE by UV-visible ground-based spectrometry

    SciTech Connect

    Sarkissian, A.; Pommereau, J.P.; Goutail, F. ); Kyro, E. )

    1994-06-22

    This paper presents results from ground-based spectrometry of twilight sky color in the UV and visible region, taken at four stations on the arctic circle. These stations observed the appearance of aerosol layers from the volcanic eruption of Mt. Pinatubo in mid 1991. The aerosol density increased steadily at lower stratospheric levels, and spread inside the polar vortex. These stations only observed one high altitude PSC during this winter campaign.

  13. Remote Sensing of Aerosol Over the Land from the Earth Observing System MODIS Instrument

    NASA Technical Reports Server (NTRS)

    Kaufman, Yoram; Tanre, Didier; Remer, Lorraine; Einaudi, Franco (Technical Monitor)

    2000-01-01

    On Dec 18, 1999, NASA launched the Moderate-Resolution Imaging Spectroradiometer (MODIS) instrument on the Earth Observing System (EOS) Terra mission, in a spectacular launch. The mission will provide morning (10:30 AM) global observations of aerosol and other related parameters. It will be followed a year later by a MODIS instrument on EOS Aqua for afternoon observations (1:30 PM). MODIS will measure aerosol over land and ocean with its eight 500 m and 250 m channels in the solar spectrum (0-41 to 2.2 micrometers). Over the land MODIS will measure the total column aerosol loading, and distinguish between submicron pollution particles and large soil particles. Standard daily products of resolution of ten kilometers and global mapped eight day and monthly products on a 1x1 degree global scale will be produced routinely and make available for no or small reproduction charge to the international community. Though the aerosol products will not be available everywhere over the land, it is expected that they will be useful for assessments of the presence, sources and transport of urban pollution, biomass burning aerosol, and desert dust. Other measurements from MODIS will supplement the aerosol information, e.g., land use change, urbanization, presence and magnitude of biomass burning fires, and effect of aerosol on cloud microphysics. Other instruments on Terra, e.g. Multi-angle Imaging SpectroRadiometer (MISR) and the Clouds and the Earth's Radiant Energy System (CERES), will also measure aerosol, its properties and radiative forcing in tandem with the MODIS measurements. During the Aqua period, there are plans to launch in 2003 the Pathfinder Instruments for Cloud and Aerosol Spaceborne Observations (PICASSO) mission for global measurements of the aerosol vertical structure, and the PARASOL mission for aerosol characterization. Aqua-MODIS, PICASSO and PARASOL will fly in formation for detailed simultaneous characterization of the aerosol three-dimensional field, which

  14. Constraining cloud lifetime effects of aerosols using A-Train satellite observations

    SciTech Connect

    Wang, Minghuai; Ghan, Steven J.; Liu, Xiaohong; Ecuyer, Tristan L.; Zhang, Kai; Morrison, H.; Ovchinnikov, Mikhail; Easter, Richard C.; Marchand, Roger; Chand, Duli; Qian, Yun; Penner, Joyce E.

    2012-08-15

    Aerosol indirect effects have remained the largest uncertainty in estimates of the radiative forcing of past and future climate change. Observational constraints on cloud lifetime effects are particularly challenging since it is difficult to separate aerosol effects from meteorological influences. Here we use three global climate models, including a multi-scale aerosol-climate model PNNL-MMF, to show that the dependence of the probability of precipitation on aerosol loading, termed the precipitation frequency susceptibility (S{sub pop}), is a good measure of the liquid water path response to aerosol perturbation ({lambda}), as both Spop and {lambda} strongly depend on the magnitude of autoconversion, a model representation of precipitation formation via collisions among cloud droplets. This provides a method to use satellite observations to constrain cloud lifetime effects in global climate models. S{sub pop} in marine clouds estimated from CloudSat, MODIS and AMSR-E observations is substantially lower than that from global climate models and suggests a liquid water path increase of less than 5% from doubled cloud condensation nuclei concentrations. This implies a substantially smaller impact on shortwave cloud radiative forcing (SWCF) over ocean due to aerosol indirect effects than simulated by current global climate models (a reduction by one-third for one of the conventional aerosol-climate models). Further work is needed to quantify the uncertainties in satellite-derived estimates of S{sub pop} and to examine S{sub pop} in high-resolution models.

  15. Assessment of 10 Year Record of Aerosol Optical Depth from OMI UV Observations

    NASA Technical Reports Server (NTRS)

    Ahn, Changwoo; Torres, Omar; Jethva, Hiren

    2014-01-01

    The Ozone Monitoring Instrument (OMI) onboard the EOS-Aura satellite provides information on aerosol optical properties by making use of the large sensitivity to aerosol absorption in the near-ultraviolet (UV) spectral region. Another important advantage of using near UV observations for aerosol characterization is the low surface albedo of all terrestrial surfaces in this spectral region that reduces retrieval errors associated with land surface reflectance characterization. In spite of the 13 × 24 square kilometers coarse sensor footprint, the OMI near UV aerosol algorithm (OMAERUV) retrieves aerosol optical depth (AOD) and single-scattering albedo under cloud-free conditions from radiance measurements at 354 and 388 nanometers. We present validation results of OMI AOD against space and time collocated Aerosol Robotic Network measured AOD values over multiple stations representing major aerosol episodes and regimes. OMAERUV's performance is also evaluated with respect to those of the Aqua-MODIS Deep Blue and Terra-MISR AOD algorithms over arid and semi-arid regions in Northern Africa. The outcome of the evaluation analysis indicates that in spite of the "row anomaly" problem, affecting the sensor since mid-2007, the long-term aerosol record shows remarkable sensor stability.

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

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

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

  17. The Amazon tall tower observatory (ATTO) site - Multi-year aerosol observations and scientific key questions

    NASA Astrophysics Data System (ADS)

    Pöhlker, C.; Barbosa, H. M.; Brito, J.; Carbone, S.; Chi, X.; Kesselmeier, J.; Ditas, F.; Pöhlker, M. L.; Manzi, A. O.; Moran, D.; Poeschl, U.; Ruckteschler, N.; Saturno, J.; Soergel, M.; Su, H.; Walter, D.; Wang, Q.; Wang, Z.; Weber, B.; Wolff, S.; Yanez-Serrano, A. M.; Artaxo, P.; Andreae, M. O.

    2015-12-01

    The Amazon tall tower observatory site is located 150 km NE of Manaus in undisturbed rain forest areas. It serves as a remote measurement station in the Amazon forest with continuous aerosol, trace gas, micrometeorological, and ecological measurements. During part of the rainy season, the atmospheric state approximates pre-industrial conditions, in strong contrast to the dry season, which is dominated by significant pollution from deforestation fires and urban emissions. This presentation will focus on aerosol studies of the past three years. It aims to provide a brief overview of the characteristic seasonality of the aerosol burden at the ATTO site. Moreover, it will discuss the following key questions and current results of the ongoing observations: (i) During the wet season and in the absence of long-range advection of African aerosols, atmospheric conditions at the ATTO site approximate a pristine state, which reveals the genuine contribution of biogenic aerosols. Biogenic particles in the super- and submicron range have been observed and their properties as well as potential sources will be discussed. (ii) In contrast to the classical new particle formation, the occurrence of ultrafine particles is comparably sparse and mainly occurs as short 'bursts', indicating a rather localized character. Our current understanding of this phenomenon and its significance for the overall aerosol burden will be addressed. (iii) Aerosol absorptivity is mainly caused by black carbon, however, indications for the presence of other light absorbing aerosol species have been found. Current results on light absorbing aerosol under clean and polluted conditions will be presented. (iv) Aerosol particles at the ATTO site are typically strongly aged and comprise pronounced internal mixtures, with important implications for their properties. Microspectroscopic analysis helps to obtain insights into atmospheric processing and its impact on particle morphology and phase state.

  18. Observational Constraint of Aerosol Effects on the CMIP5 Inter-model Spread of Adjusted Forcings

    NASA Astrophysics Data System (ADS)

    Chen, J.; Wennberg, P. O.; Jiang, J. H.; Su, H.; Bordoni, S.

    2013-12-01

    The simulated global-mean temperature (GMT) change over the past 150 years is quite consistent across CMIP5 climate models and also consistent with the observations. However, the predicted future GMT under the identical CO2 forcing is divergent. This paradox is partly due to the errors in the predicted GMT produced by historical greenhouse gas (GHG) forcing being compensated by the parameterization of aerosol cloud radiative forcing. Historical increases in anthropogenic aerosols exert an overall (but highly uncertain) cooling effect in the climate system, which partially offsets the warming due to well mixed greenhouse gases (WMGHGs). Because aerosol concentrations are predicted to eventually decrease in future scenarios, climate change becomes dominated by warming due to the WMGHG. This change in the relative importance of forcing by aerosol versus WMGHG makes apparent the substantial differences in prediction of climate by WMGHG forcing. Here we investigate the role of aerosols in the context of adjusted forcing changes in the historical runs and the effect of aerosols on the cloud feedback. Our preliminary results suggest that models which are more sensitive to the increase in concentration of CO2 have a larger aerosol radiative cooling effect. By comparing the historicalMisc runs and historicalGHG runs, we find that aerosols exert a potential impact on the cloud adjusted forcings, especially shortwave cloud adjusted forcings. We use the CLIPSO, MISR and CERES data as the benchmark to evaluate the present aerosol simulations. Using satellite observations to assess the relative reliability of the different model responses and to constrain the simulated aerosol radiative forcing will contribute significantly to reducing the across model spread in future climate simulations and identifying some missing physical processes.

  19. The lofting of Western Pacific regional aerosol by island thermodynamics as observed around Borneo

    NASA Astrophysics Data System (ADS)

    Robinson, N. H.; Allan, J. D.; Trembath, J. A.; Rosenberg, P. D.; Allen, G.; Coe, H.

    2012-07-01

    Vertical profiles of aerosol chemical composition, number concentration and size were measured throughout the lower troposphere of Borneo, a large tropical island in the western Pacific Ocean. Aerosol composition, size and number concentration measurements (using an Aerodyne Aerosol Mass Spectrometer, Passive Cavity Aerosol Spectrometer Probe and Condensation Particle Counter, respectively) were made both upwind and downwind of Borneo, as well as over the island itself, on board the UK BAe-146 research aircraft as part of the OP3 project. Two meteorological regimes were identified - one dominated by isolated terrestrial convection (ITC) which peaked in the afternoon, and the other characterised by more regionally active mesoscale convective systems (MCS). Upwind profiles show aerosol to be confined to a shallow marine boundary layer below 930 ± 10 hPa (~760 m above sea level, a.s.l.). As this air mass advects over the island with the mean free troposphere synoptic flow during the ITC-dominated regime, it is convectively lofted above the terrestrial surface mixed layer to heights of between 945 ± 22 (~630 m a.s.l.) and 740 ± 44 hPa (~2740 m a.s.l.), consistent with a coupling between the synoptic steering level flow and island sea breeze circulations. Terrestrial aerosol was observed to be lofted into this higher layer through both moist convective uplift and transport through turbulent diurnal sea-breeze cells. At the peak of convective activity in the mid-afternoons, organic aerosol loadings in the lofted layer were observed to be substantially higher than in the morning (by a mean factor of three). This organic matter is dominated by secondary aerosol from processing of biogenic gas phase precursors. Aerosol number concentration profiles suggest formation of new particles aloft in the atmosphere. By the time the air mass reaches the west coast of the island, terrestrial aerosol is enhanced in the lofted layer. Such uplift of aerosol in Borneo is expected to

  20. Detailed Characterization of aerosol properties from satellite Observations using GRASP algorithm

    NASA Astrophysics Data System (ADS)

    Dubovik, O.; Litvinov, P.; Lapyonok, T.; Ducos, F.; Huang, X.; Lopatin, A.; Fuertes, D.; Torres, B.

    2015-12-01

    GRASP (Generalized Retrieval of Aerosol and Surface Properties) is rather sophisticated algorithm was developed recently by Dubovik et al. (2011, 2014) with objective of achieving more complete and accurate aerosols and surface retrieval. Specifically, GPASP searches in continuous space of solutions and doesn't utilize look-up-tables. It based on highly elaborated statistically optimized fitting. For example, it uses multi-pixel retrieval when statistically optimized inversion is implemented simultaneously for a group of satellite pixels. This allows using additional a priori information about limited variability of aerosol of surface properties in time and/or space. As a result, GRASP doesn't use any specific information about aerosol or surface type in the each observed pixel, and the results are essentially driven by observations. However GRASP retrieval takes longer computational time compare to most conventional algorithms that is the main practical challenge of employing GRASP for massive data processing. Nonetheless, in last two years, GRASP has been significantly optimized and adapted to operational needs. As a result of this optimization, GRASP has been accelerated to the level acceptable for processing large volumes of satellite observations. Recently GRASP has been applied to multi-years archives of PARASO/POLDER and ENVISAT/MERIS. Based, on the preliminary analysis GRASP results are very promising for comprehensive characterization of aerosol even for observations over bright surfaces and for monitoring very high aerosol loading events (with AOD 2 or 3). In addition, it was made the attempts to estimate such aerosol characteristics as aerosol height, air mass, radiative forcing, aerosol type, etc. The results and illustrations will be presented.

  1. A Missing Wintertime Source of Aerosols over the Arctic Inferred from Satellite and In Situ Observations

    NASA Astrophysics Data System (ADS)

    Jaegle, L.; Di Pierro, M.

    2013-12-01

    We use observations of aerosol extinction from the CALIOP instrument on the CALIPSO satellite to map the aerosol distribution over the Arctic as a function of season and altitude between 2006 and 2010. The resulting aerosol distribution is compared to a simulation from the GEOS-Chem chemical transport model. CALIOP observations in the lower troposphere over the High Arctic (>70°N) display a strong winter maximum of 15 Mm-1. The GEOS-Chem model calculates extinction values that are a factor of 2-3 too low for this widespread wintertime haze. In contrast, the model captures the low Arctic and free tropospheric CALIOP extinctions quite well. Comparisons to in situ nephelometer observations at Barrow in Alaska and Alert in Canada confirm this surface High Arctic underestimate. Furthermore, while GEOS-Chem reproduces ground-based observations of sulfate aerosol concentrations obtained at both sites, it significantly underestimates wintertime concentrations of fine mode sea salt aerosols. We hypothesize that the gap between observed and modeled aerosol extinction is due to a missing source of sea salt over the High Arctic during winter. The seasonality and spatial distribution of this missing source is consistent with a blowing snow source over Arctic sea ice. We examine whether the blowing snow parameterization of Yang et al. (2008) can help reconcile model and observations.

  2. Global and Seasonal Aerosol Optical Depths Derived From Ultraviolet Observations by Satellites (TOMS)

    NASA Technical Reports Server (NTRS)

    Herman, J. R.; Torres, O.

    1999-01-01

    It has been shown that absorbing aerosols (dust, smoke, volcanic ash) can be detected in the ultraviolet wavelengths (331 nm to 380 nm) from satellite observations (TOMS, Total Ozone Mapping Spectrometer) over both land and water. The theoretical basis for these observations and their conversions to optical depths is discussed in terms of an aerosol index AI or N-value residue (assigned positive for absorbing aerosols). The theoretical considerations show that negative values of the AI frequently represent the presence of non-absorbing aerosols (NA) in the troposphere (mostly pollution in the form of sulfates, hydrocarbons, etc., and some natural sulfate aerosols) with particle sizes near 0.1 to 0.2 microns or less. The detection of small-particle non-absorbing aerosols from the measured backscattered radiances is based on the observed wavelength dependence from Mie scattering after the background Rayleigh scattering is subtracted. The Mie scattering from larger particles, 1 micron or more (e.g., cloud water droplets) has too small a wavelength dependence to be detected by this method. In regions that are mostly cloud free, aerosols of all sizes can be seen in the single channel 380 nm or 360 nm radiance data. The most prominent Al feature observed is the strong asymmetry in aerosol amount between the Northern and Southern Hemispheres, with the large majority of NA occurring above 20degN latitude. The maximum values of non-absorbing aerosols are observed over the eastern U.S. and most of western Europe corresponding to the areas of highest industrial pollution. Annual cycles in the amount of NA are observed over Europe and North America with maxima occurring in the summer corresponding to times of minimum wind transport. Similarly, the maxima in the winter over the Atlantic Ocean occurs because of wind borne transport from the land. Most regions of the world have the maximum amount of non-absorbing aerosol in the December to January period except for the eastern

  3. The regime of biomass burning aerosols over the Mediterranean basin based on satellite observations

    NASA Astrophysics Data System (ADS)

    Kalaitzi, Nikoleta; Gkikas, Antonis; Papadimas, Christos. D.; Hatzianastassiou, Nikolaos; Torres, Omar; Mihalopoulos, Nikolaos

    2016-04-01

    Biomass burning (BB) aerosol particles have significant effects on global and regional climate, as well as on regional air quality, visibility, cloud processes and human health.Biomass burning contributes by about 40% to the global emission of black carbonBC, and BB aerosols can exert a significant positive radiative forcing. The BB aerosols can originate from natural fires and human induced burning, such as wood or agricultural waste. However, the magnitude, but also the sign of the radiative forcing of BB aerosols is still uncertain, according to the third assessment report of IPCC (2013). Moreover, there are significant differences between different models as to their representation (inventories) of BB aerosols, more than for others, e.g. of fossil fuel origin. Therefore, it is important to better understand the spatial and temporal regime of BB aerosols. This is attempted here for the broader Mediterranean basin, which is a very interesting study area for aerosols, also being one of the most climaticallysensitive world regions. The determination of spatial and temporal regime of Mediterranean BB aerosols premises the identification of these particles at a complete spatial and long temporal coverage. Such a complete coverage is only ensured by contemporary satellite observations, which offer a challenging ability to characterize the existence of BB aerosols. This is possible thanks to the current availability of derived satellite products offering information on the size and absorption/scattering ability of aerosol particles. A synergistic use of such satellite aerosol data is made here, in conjunction with a developed algorithm, in order to identify the existence of BB aerosols over the Mediterranean basin over the 11-year period from 2005 to 2015. The algorithm operates, on a daily basis and at 1°×1°latitude-longitude resolution, setting threshold values (criteria) for specific physical and optical properties, which are representative of BB aerosols. More

  4. Observed correlations between aerosol and cloud properties in an Indian Ocean trade cumulus regime

    NASA Astrophysics Data System (ADS)

    Pistone, K.; Praveen, P. S.; Thomas, R. M.; Ramanathan, V.; Wilcox, E.; Bender, F. A.-M.

    2015-10-01

    There are many contributing factors which determine the micro- and macrophysical properties of clouds, including atmospheric structure, dominant meteorological conditions, and aerosol concentration, all of which may be coupled to one another. In the quest to determine aerosol effects on clouds, these potential relationships must be understood, as changes in atmospheric conditions due to aerosol may change the expected magnitude of indirect effects by altering cloud properties in unexpected ways. Here we describe several observed correlations between aerosol conditions and cloud and atmospheric properties in the Indian Ocean winter monsoon season. In the CARDEX (Cloud, Aerosol, Radiative forcing, Dynamics EXperiment) field campaign conducted in February and March 2012 in the northern Indian Ocean, continuous measurements of atmospheric precipitable water vapor and the liquid water path (LWP) of trade cumulus clouds were made, concurrent with measurements of water vapor flux, cloud and aerosol vertical profiles, meteorological data, and surface and total-column aerosol. Here we present evidence of a positive correlation between aerosol and cloud LWP which becomes clear after the data are filtered to control for the natural meteorological variability in the region. We then use the aircraft and ground observatory measurements to explore the mechanisms behind the observed aerosol-LWP correlation. We determine that increased boundary-layer humidity lowering the cloud base is responsible for the observed increase in cloud liquid water. Large-scale analysis indicates that high pollution cases originate with a highly-polluted boundary layer air mass approaching the observatory from a northwesterly direction. This polluted mass exhibits higher temperatures and humidity than the clean case, the former of which may be attributable to heating due to aerosol absorption of solar radiation over the subcontinent. While high temperature conditions dispersed along with the high-aerosol

  5. Evaluation of Aerosol-cloud Interaction in the GISS Model E Using ARM Observations

    NASA Technical Reports Server (NTRS)

    DeBoer, G.; Bauer, S. E.; Toto, T.; Menon, Surabi; Vogelmann, A. M.

    2013-01-01

    Observations from the US Department of Energy's Atmospheric Radiation Measurement (ARM) program are used to evaluate the ability of the NASA GISS ModelE global climate model in reproducing observed interactions between aerosols and clouds. Included in the evaluation are comparisons of basic meteorology and aerosol properties, droplet activation, effective radius parameterizations, and surface-based evaluations of aerosol-cloud interactions (ACI). Differences between the simulated and observed ACI are generally large, but these differences may result partially from vertical distribution of aerosol in the model, rather than the representation of physical processes governing the interactions between aerosols and clouds. Compared to the current observations, the ModelE often features elevated droplet concentrations for a given aerosol concentration, indicating that the activation parameterizations used may be too aggressive. Additionally, parameterizations for effective radius commonly used in models were tested using ARM observations, and there was no clear superior parameterization for the cases reviewed here. This lack of consensus is demonstrated to result in potentially large, statistically significant differences to surface radiative budgets, should one parameterization be chosen over another.

  6. Simultaneous observations of aerosol-cloud-albedo interactions with three stacked unmanned aerial vehicles.

    PubMed

    Roberts, G C; Ramana, M V; Corrigan, C; Kim, D; Ramanathan, V

    2008-05-27

    Aerosol impacts on climate change are still poorly understood, in part, because the few observations and methods for detecting their effects are not well established. For the first time, the enhancement in cloud albedo is directly measured on a cloud-by-cloud basis and linked to increasing aerosol concentrations by using multiple autonomous unmanned aerial vehicles to simultaneously observe the cloud microphysics, vertical aerosol distribution, and associated solar radiative fluxes. In the presence of long-range transport of dust and anthropogenic pollution, the trade cumuli have higher droplet concentrations and are on average brighter. Our observations suggest a higher sensitivity of radiative forcing by trade cumuli to increases in cloud droplet concentrations than previously reported owing to a constrained droplet radius such that increases in droplet concentrations also increase cloud liquid water content. This aerosol-cloud forcing efficiency is as much as -60 W m(-2) per 100% percent cloud fraction for a doubling of droplet concentrations and associated increase of liquid water content. Finally, we develop a strategy for detecting aerosol-cloud interactions based on a nondimensional scaling analysis that relates the contribution of single clouds to albedo measurements and illustrates the significance of characterizing cloud morphology in resolving radiometric measurements. This study demonstrates that aerosol-cloud-albedo interactions can be directly observed by simultaneous observations below, in, and above the clouds. PMID:18499803

  7. Observation-constrained Estimation of Aerosol Climate Impacts over S Asia

    NASA Astrophysics Data System (ADS)

    Feng, Y.; Kotamarthi, V. R.; Jefferson, A.; Wilcox, E. M.; Bender, F.; Pistone, K.; Praveen, P. S.; Thomas, R. M.; Ramanathan, V.

    2012-12-01

    Climate impacts of elevated aerosols over S. Asia have been studied extensively. Despite different methods employed and uncertainties, one clear message is that these aerosols have a large impact on the regional energy balance. However, uncertainty in the elevated aerosol absorption, as well as poor fidelity in model representations of aerosol-cloud interactions contribute to the discrepancies in quantifying the aerosol influences on monsoon circulation and rainfall. The main goal of this study is to examine the latitudinal heating gradient and the aerosol impact on the hydrological cycle during the pre-monsoon, with observational constraints on the aerosol vertical distribution. We run a 12-km regional climate model (WRF-Chem) driven by the NCEP analysis data from August 2011 to March 2012. During this time period, the ground-based profiling of aerosol extinction, cloud liquid water, water vapor, and temperature were taken at Nainital (29.38°N, 79.45°E) as part of the Ganges Valley Experiment (GVAX). It is the first time that such vertical profiling data sets are available in the northern Indian subcontinent for such a long period. In the pre-monsoon season (Feb-Mar), the regional model simulations show good agreement in the aerosol optical depth (AOD; 0.1~0.2) and black carbon (BC; ~0.8 ug/m3) concentrations compared with the surface observations at Nainital. The observed diurnal variation in BC concentration, peaking in the afternoon and lowering at night, is also captured by the model as a result of the thermal convection from the polluted valley. The simulated OC/BC ratio is about 2~4 near the surface, which is lower than observations, implying that we may underestimate the secondary organic formation from the biomass burning or biogenic sources. Spectral measurements of aerosol absorption will be used to investigate the absorption of OC in the UV and visible bands. During this time, surface and in situ profiling of aerosols and clouds were also made during

  8. Stellar intensity interferometry: experimental steps toward long-baseline observations

    NASA Astrophysics Data System (ADS)

    LeBohec, Stephan; Adams, Ben; Bond, Isobel; Bradbury, Stella; Dravins, Dainis; Jensen, Hannes; Kieda, David B.; Kress, Derrick; Munford, Edward; Nuñez, Paul D.; Price, Ryan; Ribak, Erez; Rose, Joachim; Simpson, Harold; Smith, Jeremy

    2010-07-01

    Experiments are in progress to prepare for intensity interferometry with arrays of air Cherenkov telescopes. At the Bonneville Seabase site, near Salt Lake City, a testbed observatory has been set up with two 3-m air Cherenkov telescopes on a 23-m baseline. Cameras are being constructed, with control electronics for either off- or online analysis of the data. At the Lund Observatory (Sweden) and in Technion (Israel) and at the University of Utah (USA), laboratory intensity interferometers simulating stellar observations have been set up and experiments are in progress, using various analog and digital correlators, reaching 1.4 ns time resolution, to analyze signals from pairs of laboratory telescopes.

  9. Impact of Asian Aerosols on Precipitation Over California: An Observational and Model Based Approach

    NASA Technical Reports Server (NTRS)

    Naeger, Aaron R.; Molthan, Andrew L.; Zavodsky, Bradley T.; Creamean, Jessie M.

    2015-01-01

    Dust and pollution emissions from Asia are often transported across the Pacific Ocean to over the western United States. Therefore, it is essential to fully understand the impact of these aerosols on clouds and precipitation forming over the eastern Pacific and western United States, especially during atmospheric river events that account for up to half of California's annual precipitation and can lead to widespread flooding. In order for numerical modeling simulations to accurately represent the present and future regional climate of the western United States, we must account for the aerosol-cloud-precipitation interactions associated with Asian dust and pollution aerosols. Therefore, we have constructed a detailed study utilizing multi-sensor satellite observations, NOAA-led field campaign measurements, and targeted numerical modeling studies where Asian aerosols interacted with cloud and precipitation processes over the western United States. In particular, we utilize aerosol optical depth retrievals from the NASA Moderate Resolution Imaging Spectroradiometer (MODIS), NOAA Geostationary Operational Environmental Satellite (GOES-11), and Japan Meteorological Agency (JMA) Multi-functional Transport Satellite (MTSAT) to effectively detect and monitor the trans-Pacific transport of Asian dust and pollution. The aerosol optical depth (AOD) retrievals are used in assimilating the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) in order to provide the model with an accurate representation of the aerosol spatial distribution across the Pacific. We conduct WRF-Chem model simulations of several cold-season atmospheric river events that interacted with Asian aerosols and brought significant precipitation over California during February-March 2011 when the NOAA CalWater field campaign was ongoing. The CalWater field campaign consisted of aircraft and surface measurements of aerosol and precipitation processes that help extensively validate our WRF

  10. Observations of relative humidity effects on aerosol light scattering in the Yangtze River Delta of China

    NASA Astrophysics Data System (ADS)

    Zhang, L.; Sun, J. Y.; Shen, X. J.; Zhang, Y. M.; Che, H.; Ma, Q. L.; Zhang, Y. W.; Zhang, X. Y.; Ogren, J. A.

    2015-07-01

    Scattering of solar radiation by aerosol particles is highly dependent on relative humidity (RH) as hygroscopic particles take up water with increasing RH. To achieve a better understanding of the effect of aerosol hygroscopic growth on light scattering properties and radiative forcing, the aerosol scattering coefficients at RH in the range of 40 to ~ 90 % were measured using a humidified nephelometer system in the Yangtze River Delta of China in March 2013. In addition, the aerosol size distribution and chemical composition were measured. During the observation period, the mean and standard deviation (SD) of enhancement factors at RH = 85 % for the scattering coefficient (f(85 %)), backscattering coefficient (fb(85 %)), and hemispheric backscatter fraction (fβ(85 %)) were 1.58 ± 0.12, 1.25 ± 0.07, and 0.79 ± 0.04, respectively, i.e., aerosol scattering coefficient and backscattering coefficient increased by 58 and 25 % as the RH increased from 40 to 85 %. Concurrently, the aerosol hemispheric backscatter fraction decreased by 21 %. The relative amount of organic matter (OM) or inorganics in PM1 was found to be a main factor determining the magnitude of f(RH). The highest values of f(RH) corresponded to the aerosols with a small fraction of OM, and vice versa. The relative amount of NO3- in fine particles was strongly correlated with f(85 %), which suggests that NO3- played a vital role in aerosol hygroscopic growth during this study. The mass fraction of nitrate also had a close relationship to the curvature of the humidograms; higher mass fractions of nitrate were associated with humidograms that had the least curvature. Aerosol hygroscopic growth caused a 47 % increase in the calculated aerosol direct radiative forcing at 85 % RH, compared to the forcing at 40 % RH.

  11. Estimating trace gas and aerosol emissions over South America: Relationship between fire radiative energy released and aerosol optical depth observations

    NASA Astrophysics Data System (ADS)

    Pereira, Gabriel; Freitas, Saulo R.; Moraes, Elisabete Caria; Ferreira, Nelson Jesus; Shimabukuro, Yosio Edemir; Rao, Vadlamudi Brahmananda; Longo, Karla M.

    2009-12-01

    Contemporary human activities such as tropical deforestation, land clearing for agriculture, pest control and grassland management lead to biomass burning, which in turn leads to land-cover changes. However, biomass burning emissions are not correctly measured and the methods to assess these emissions form a part of current research area. The traditional methods for estimating aerosols and trace gases released into the atmosphere generally use emission factors associated with fuel loading and moisture characteristics and other parameters that are hard to estimate in near real-time applications. In this paper, fire radiative power (FRP) products were extracted from Moderate Resolution Imaging Spectroradiometer (MODIS) and from the Geostationary Operational Environmental Satellites (GOES) fire products and new South America generic biomes FRE-based smoke aerosol emission coefficients were derived and applied in 2002 South America fire season. The inventory estimated by MODIS and GOES FRP measurements were included in Coupled Aerosol-Tracer Transport model coupled to the Brazilian developments on the Regional Atmospheric Modeling System (CATT-BRAMS) and evaluated with ground truth collected in Large Scale Biosphere-Atmosphere Smoke, Aerosols, Clouds, rainfall, and Climate (SMOCC) and Radiation, Cloud, and Climate Interactions (RaCCI). Although the linear regression showed that GOES FRP overestimates MODIS FRP observations, the use of a common external parameter such as MODIS aerosol optical depth product could minimize the difference between sensors. The relationship between the PM 2.5μm (Particulate Matter with diameter less than 2.5 μm) and CO (Carbon Monoxide) model shows a good agreement with SMOCC/RaCCI data in the general pattern of temporal evolution. The results showed high correlations, with values between 0.80 and 0.95 (significant at 0.5 level by student t test), for the CATT-BRAMS simulations with PM 2.5μm and CO.

  12. Dust aerosol emission over the Sahara during summertime from Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) observations

    NASA Astrophysics Data System (ADS)

    Todd, Martin C.; Cavazos-Guerra, Carolina

    2016-03-01

    Dust aerosols are an important component of the climate system and a challenge to incorporate into weather and climate models. Information on the location and magnitude of dust emission remains a key information gap to inform model development. Inadequate surface observations ensure that satellite data remain the primary source of this information over extensive and remote desert regions. Here, we develop estimates of the relative magnitude of active dust emission over the Sahara desert based on data from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP). Utilising the unique vertical profile of aerosol characteristics provided by CALIOP our algorithm identifies emission from aerosol extinction and lidar backscatter in the near surface layers. From the long-term CALIOP archive of day and night-time orbits over 2006-13 we construct coarse resolution maps of a new dust emission index (DEI) for the Sahara desert during the peak summer dust season (June to September). The spatial structure of DEI indicates highest emission over a broad zone focused on the border regions of Southern Algeria, Northern Mali and northwest Niger, displaced substantially (∼7°) to the east of the mean maximum in satellite-derived aerosol optical depth. In this region night-time emission exceeds that during the day. The DEI maps substantially corroborate recently derived dust source frequency count maps based on back-tracking plumes in high temporal resolution SEVIRI imagery. As such, a convergence of evidence from multiple satellite data sources using independent methods provides an increasingly robust picture of Saharan dust emission sources. Various caveats are considered. As such, quantitative estimates of dust emission may require a synergistic combined multi-sensor analysis.

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

    NASA Technical Reports Server (NTRS)

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

    2002-01-01

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

  14. 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.

  15. A new technique for measuring aerosols with moonlight observations and a sky background model

    NASA Astrophysics Data System (ADS)

    Jones, Amy; Noll, Stefan; Kausch, Wolfgang; Kimeswenger, Stefan; Szyszka, Ceszary; Unterguggenberger, Stefanie

    2014-05-01

    There have been an ample number of studies on aerosols in urban, daylight conditions, but few for remote, nocturnal aerosols. We have developed a new technique for investigating such aerosols using our sky background model and astronomical observations. With a dedicated observing proposal we have successfully tested this technique for nocturnal, remote aerosol studies. This technique relies on three requirements: (a) sky background model, (b) observations taken with scattered moonlight, and (c) spectrophotometric standard star observations for flux calibrations. The sky background model was developed for the European Southern Observatory and is optimized for the Very Large Telescope at Cerro Paranal in the Atacama desert in Chile. This is a remote location with almost no urban aerosols. It is well suited for studying remote background aerosols that are normally difficult to detect. Our sky background model has an uncertainty of around 20 percent and the scattered moonlight portion is even more accurate. The last two requirements are having astronomical observations with moonlight and of standard stars at different airmasses, all during the same night. We had a dedicated observing proposal at Cerro Paranal with the instrument X-Shooter to use as a case study for this method. X-Shooter is a medium resolution, echelle spectrograph which covers the wavelengths from 0.3 to 2.5 micrometers. We observed plain sky at six different distances (7, 13, 20, 45, 90, and 110 degrees) to the Moon for three different Moon phases (between full and half). Also direct observations of spectrophotometric standard stars were taken at two different airmasses for each night to measure the extinction curve via the Langley method. This is an ideal data set for testing this technique. The underlying assumption is that all components, other than the atmospheric conditions (specifically aerosols and airglow), can be calculated with the model for the given observing parameters. The scattered

  16. Observation of aerosol parameters at Saga using GOSAT product validation lidar

    NASA Astrophysics Data System (ADS)

    Takubo, Shoichiro; Okumura, Hiroshi; Kawasaki, Takeru; Abdullah, Indra Nugraha; Uchino, Osamu; Morino, Isamu; Yokota, Tatsuya; Nagai, Tomohiro; Sakai, Tetsu; Maki, Takashi; Arai, Kohei

    2012-11-01

    Greenhouse gases Observation SATellite (GOSAT) was launched to enable the precise monitoring of the density of carbon dioxide by combining global observation data sent from space with data obtained on land, and with simulation models. In addition, observation of methane, another greenhouse gas, has been considered. For validation of GOSAT data products, ground-base observation with Fourier Transform Spectrometer (FTS), aerosol lidar and ozone-DIAL (DIfferencial Absorption Lidar) at Saga University, JAPAN has been continued since March, 2011. In this article, observation results obtained from aerosol lidar are reported.

  17. The Asian Dust and Aerosol Lidar Observation Network (AD-NET): Strategy and Progress

    NASA Astrophysics Data System (ADS)

    Nishizawa, Tomoaki; Sugimoto, Nobuo; Matsui, Ichiro; Shimizu, Atsushi; Higurashi, Akiko; Jin, Yoshitaka

    2016-06-01

    We have operated a ground-based lidar network AD-Net using dual wavelength (532, 1064nm) depolarization Mie lidar continuously and observed movement of Asian dust and air pollution aerosols in East Asia since 2001. This lidar network observation contributed to understanding of the occurrence and transport mechanisms of Asian dust, validation of chemical transport models, data assimilation and epidemiologic studies. To better understand the optical and microphysical properties, externally and internally mixing states, and the movements of Asian dust and airpollution aerosols, we go forward with introducing a multi-wavelength Raman lidar to the AD-Net and developing a multi-wavelength technique of HSRL in order to evaluate optical concentrations of more aerosol components. We will use this evolving AD-Net for validation of Earth-CARE satellite observation and data assimilation to evaluate emissions of air pollution and dust aerosols in East Asia. We go forward with deploying an in-situ instrument polarization optical particle counter (POPC), which can measure size distributions and non-sphericity of aerosols, to several main AD-Net sites and conducting simultaneous observation of POPC and lidar to clarify internally mixed state of Asian dust and air pollution aerosols transported from the Asian continent to Japan.

  18. Surface-based observation of aerosol indirect effect in the Mid-Atlantic region

    NASA Astrophysics Data System (ADS)

    Nzeffe, Fonya; Joseph, Everette; Min, Qilong

    2008-11-01

    A method for assessing the aerosol indirect effect based on back trajectory analysis and cloud and aerosol properties derived from a combination of observations from the Multifilter Rotating Shadow Band Radiometer and microwave radiometer at a newly established atmospheric measurement field station in the Baltimore-Washington corridor is reported in this article. Six months of aerosol and cloud optical depth data are segregated according to air mass history based on back trajectory analysis. Under stagnant and polluted conditions where air flow across the region is predominantly from west-southwest, aerosol optical depth is on average three to four times greater than in air masses that advect rapidly from north and east. When sorted by mean cloud liquid water path, cloud-droplet effective radius in polluted air masses is on average 0.9 μm smaller than that observed under more pristine conditions. Analysis is presented to confirm the statistical significance of this result.

  19. Characterization of the Aerosol Instrument Package for the In-service Aircraft Global Observing System IAGOS

    NASA Astrophysics Data System (ADS)

    Bundke, Ulrich; Berg, Marcel; Tettig, Frank; Franke, Harald; Petzold, Andreas

    2015-04-01

    The atmospheric aerosol influences the climate twofold via the direct interaction with solar radiation and indirectly effecting microphysical properties of clouds. The latter has the largest uncertainty according to the last IPPC Report. A measured in situ climatology of the aerosol microphysical properties is needed to reduce the reported uncertainty of the aerosol climate impact. The European Research Infrastructure IAGOS (In-service Aircraft for a Global Observing System; www.iagos.org) responds to the increasing requests for long-term, routine in situ observational data by using commercial passenger aircraft as measurement platform. However, scientific instrumentation for the measurement of atmospheric constituents requires major modifications before being deployable aboard in-service passenger aircraft. The IAGOS Aerosol Package (IAGOS-P2C) consists of two modified Butanol based CPCs (Model Grimm 5.410) and one optical particle counter (Model Grimm Sky OPC 1.129). A thermodenuder at 250°C is placed upstream the second CPC, thus the number concentrations of the total aerosol and the non-volatile aerosol fraction is measured. The Sky OPC measures the size distribution in the rage theoretically up to 32 μ m. Because of the inlet cut off diameter of D50=3 μ m we are using the 16 channel mode in the range of 250 nm - 2.5 μ m at 1 Hz resolution. In this presentation the IAGOS Aerosol package is characterized for pressure levels relevant for the planned application, down to cruising level of 150 hPa including the inlet system. In our aerosol lab we have tested the system against standard instrumentation with different aerosol test substances in a long duration test. Particle losses are characterized for the inlet system. In addition first results for airborne measurements are shown from a first field campaign.

  20. Aerosol and Cloud-Nucleating Particle Observations during an Atmospheric River Event

    NASA Astrophysics Data System (ADS)

    DeMott, P. J.; McCluskey, C. S.; Petters, M.; Suski, K. J.; Levin, E. J.; Hill, T. C. J.; Atwood, S. A.; Schill, G. P.; Rocci, K.; Boose, Y.; Martin, A.; Cornwell, G.; Al-Mashat, H.; Moore, K.; Prather, K. A.; Rothfuss, N.; Taylor, H.; Leung, L. R.; Tomlinson, J. M.; Mei, F.; Hubbe, J. M.; Rosenfeld, D.; Spackman, J. R.; Fairall, C. W.; Creamean, J.; White, A. B.; Kreidenweis, S. M.

    2015-12-01

    The multi-agency CalWater 2015 project occurred over North Central CA and the Eastern Pacific during January to March 2015 (Spackman et al., this session). The goals of the campaign were to document the structure of atmospheric rivers (ARs) that deliver much of the water vapor associated with major winter storms along the U.S. West Coast and to investigate the modulating effect of aerosols on precipitation. Aerosol sources that may influence orographic cloud properties for air lifted over the mountains in California in winter include pollution, biomass burning, soil dusts and marine aerosols, but their roles will also be influenced by transport, vertical stratification, and scavenging processes. We present results from a comprehensive study of aerosol distributions, compositions, and cloud nucleating properties during an intense winter storm during February 2015, including data from an NSF-supported measurement site at Bodega Bay, from the DOE-ARM Cloud Aerosol Precipitation Experiment that included sampling on the NOAA RV Ron Brown offshore and the G-1 aircraft over ocean and land, and with context provided by other NOAA aircraft and remote sensing facilities. With a special focus on the coastal site, we discuss changes in aerosol distributions, aerosol hygroscopicity, and number concentrations of fluorescent particles, cloud condensation nuclei (CCN), and ice nucleating particles (INPs) during the AR event. We compare with periods preceding and following the event. For example, total aerosol number and surface area concentrations at below 0.5 μm diameter decreased from typical values of a few thousand cm-3 and 100 μm2 cm-3, respectively, to a few hundred cm-3 and 10 μm2cm-3 at Bodega Bay during the AR event. CCN concentrations were similarly lower, but hygroscopicity parameter (kappa) increased from typical values of 0.2 to values > 0.5 during the AR.INP and fluorescent particle number concentrations were generally lower during the AR event than at any other

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

    NASA Technical Reports Server (NTRS)

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

    2008-01-01

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

  2. Observation operator for the assimilation of aerosol type resolving satellite measurements into a chemical transport model

    NASA Astrophysics Data System (ADS)

    Schroedter-Homscheidt, M.; Elbern, H.; Holzer-Popp, T.

    2010-11-01

    Modelling of aerosol particles with chemical transport models is still based mainly on static emission databases while episodic emissions cannot be treated sufficiently. To overcome this situation, a coupling of chemical mass concentration modelling with satellite-based measurements relying on physical and optical principles has been developed. This study deals with the observation operator for a component-wise assimilation of satellite measurements. It treats aerosol particles classified into water soluble, water insoluble, soot, sea salt and mineral dust containing aerosol particles in the atmospheric boundary layer as separately assimilated aerosol components. It builds on a mapping of aerosol classes used both in observation and model space taking their optical and chemical properties into account. Refractive indices for primary organic carbon particles, anthropogenic particles, and secondary organic species have been defined based on a literature review. Together with a treatment of different size distributions in observations and model state, this allows transforming the background from mass concentrations into aerosol optical depths. A two-dimensional, variational assimilation is applied for component-wise aerosol optical depths. Error covariance matrices are defined based on a validation against AERONET sun photometer measurements. Analysis fields are assessed threefold: (1) through validation against AERONET especially in Saharan dust outbreak situations, (2) through comparison with the British Black Smoke and Sulphur Dioxide Network for soot-containing particles, and (3) through comparison with measurements of the water soluble components SO4, NH4, and NO3 conducted by the EMEP (European Monitoring and Evaluation Programme) network. Separately, for the water soluble, the soot and the mineral dust aerosol components a bias reduction and subsequent a root mean square error reduction is observed in the analysis for a test period from July to November 2003

  3. Observation operator for the assimilation of aerosol type resolving satellite measurements into a chemical transport model

    NASA Astrophysics Data System (ADS)

    Schroedter-Homscheidt, M.; Elbern, H.; Holzer-Popp, T.

    2010-06-01

    Modelling of aerosol particles with chemical transport models is still based mainly on static emission databases while episodic emissions can not be treated sufficiently. To overcome this situation, a coupling of chemical mass concentration modelling with satellite-based measurements relying on physical and optical principles has been developed. This study deals with the observation operator for a component-wise assimilation of satellite measurements. It treats aerosol particles classified into water soluble, water insoluble, soot, sea salt and mineral dust containing aerosol particles in the atmospheric boundary layer as separately assimilated aerosol components. It builds on a mapping of aerosol classes used both in observation and model space taking their optical and chemical properties into account. Refractive indices for primary organic carbon particles, anthropogenic particles, and secondary organic species have been defined based on a literature review. Together with a treatment of different size distributions in observations and model state, this allows transforming the background from mass concentrations into aerosol optical depths. A two-dimensional, variational assimilation is applied for component-wise aerosol optical depths. Error covariance matrices are defined based on a validation against AERONET sun photometer measurements. Analysis fields are assessed threefold: (1) through validation against AERONET especially in Saharan dust outbreak situations, (2) through comparison with the British Black Smoke and Sulphur Dioxide Network for soot-containing particles, and (3) through comparison with measurements of the water soluble components SO4, NH4, and NO3 conducted by the EMEP (European Monitoring and Evaluation Programme) network. Separately, for the water soluble, the soot and the mineral dust aerosol components a bias reduction and subsequent a root mean square error reduction is observed in the analysis for a test period from July to November 2003

  4. Observed correlations between aerosol and cloud properties in an Indian Ocean trade cumulus regime

    SciTech Connect

    Pistone, Kristina; Praveen, Puppala S.; Thomas, Rick M.; Ramanathan, Veerabhadran; Wilcox, Eric M.; Bender, Frida A. -M.

    2016-01-01

    There are many contributing factors which determine the micro- and macrophysical properties of clouds, including atmospheric vertical structure, dominant meteorological conditions, and aerosol concentration, all of which may be coupled to one another. In the quest to determine aerosol effects on clouds, these potential relationships must be understood. Here we describe several observed correlations between aerosol conditions and cloud and atmospheric properties in the Indian Ocean winter monsoon season.

    In the CARDEX (Cloud, Aerosol, Radiative forcing, Dynamics EXperiment) field campaign conducted in February and March 2012 in the northern Indian Ocean, continuous measurements were made of atmospheric precipitable water vapor (PWV) and the liquid water path (LWP) of trade cumulus clouds, concurrent with measurements of water vapor flux, cloud and aerosol vertical profiles, meteorological data, and surface and total-column aerosol from instrumentation at a ground observatory and on small unmanned aircraft. We present observations which indicate a positive correlation between aerosol and cloud LWP only when considering cases with low atmospheric water vapor (PWV  < 40 kg m−2), a criterion which acts to filter the data to control for the natural meteorological variability in the region.

    We then use the aircraft and ground-based measurements to explore possible mechanisms behind this observed aerosol–LWP correlation. The increase in cloud liquid water is found to coincide with a lowering of the cloud base, which is itself attributable to increased boundary layer humidity in polluted conditions. High pollution is found to correlate with both higher temperatures and higher humidity measured throughout the boundary layer. A large-scale analysis, using satellite observations and meteorological reanalysis, corroborates these covariations: high-pollution cases are shown to originate as a highly polluted boundary layer air mass

  5. Observed correlations between aerosol and cloud properties in an Indian Ocean trade cumulus regime

    DOE PAGESBeta

    Pistone, Kristina; Praveen, Puppala S.; Thomas, Rick M.; Ramanathan, Veerabhadran; Wilcox, Eric M.; Bender, Frida A.-M.

    2016-04-27

    There are many contributing factors which determine the micro- and macrophysical properties of clouds, including atmospheric vertical structure, dominant meteorological conditions, and aerosol concentration, all of which may be coupled to one another. In the quest to determine aerosol effects on clouds, these potential relationships must be understood. Here we describe several observed correlations between aerosol conditions and cloud and atmospheric properties in the Indian Ocean winter monsoon season.In the CARDEX (Cloud, Aerosol, Radiative forcing, Dynamics EXperiment) field campaign conducted in February and March 2012 in the northern Indian Ocean, continuous measurements were made of atmospheric precipitable water vapor (PWV)more » and the liquid water path (LWP) of trade cumulus clouds, concurrent with measurements of water vapor flux, cloud and aerosol vertical profiles, meteorological data, and surface and total-column aerosol from instrumentation at a ground observatory and on small unmanned aircraft. We present observations which indicate a positive correlation between aerosol and cloud LWP only when considering cases with low atmospheric water vapor (PWV < 40 kg m–2), a criterion which acts to filter the data to control for the natural meteorological variability in the region.We then use the aircraft and ground-based measurements to explore possible mechanisms behind this observed aerosol–LWP correlation. The increase in cloud liquid water is found to coincide with a lowering of the cloud base, which is itself attributable to increased boundary layer humidity in polluted conditions. High pollution is found to correlate with both higher temperatures and higher humidity measured throughout the boundary layer. A large-scale analysis, using satellite observations and meteorological reanalysis, corroborates these covariations: high-pollution cases are shown to originate as a highly polluted boundary layer air mass approaching the observatory from a

  6. Satellite observation of aerosol - cloud interactions over semi-arid and arid land regions

    NASA Astrophysics Data System (ADS)

    Klüser, L.; Holzer-Popp, T.

    2012-04-01

    Satellite observations from three different sources are used to study the interactions between aerosol and ice clouds in five semi-arid and arid land regions over Africa and Asia, reaching from the South-African Kalahari to the Taklimakan and Gobi in Mongolia. (1) Six years of Aqua MODIS cloud and aerosol observations (including "Deep Blue" retrievals) which contain a qualitative separation into coarse and fine mode aerosol are analysed. (2) Five years of APOLLO cloud observations and SYNAER aerosol retrievals which allow discriminating between mineral dust and soot dominated cases from AATSR and SCIAMACHY on ENVISAT are exploited. (3) Moreover IASI provides one year of ice cloud and mineral dust observations over land retrieved with a newly developed method based on singular vector decomposition. Cloud top temperature observations are used to asses the state of convection and to statistically re-project observation distributions of cloud properties to background conditions. Then the difference between observation density distributions of background and re-projected aerosol-contaminated samples can be evaluated. By such way of analysis the influence of different cloud development stages, which also manifest in seasonal cycles of cloud properties, can be minimised. The analysis of the various observation density distributions shows that liquid water and ice effective radius is mainly decreased for increased total aerosol content for both aerosol types, biomass burning aerosols and mineral dust, separately. Two different modes of aerosol impacts on cloud optical depth can be shown. Optical depth is mainly increased, directly following the theory of the so-called "Twomey effect". In the West African Sahel a decrease of cloud water path (for both liquid water and ice) under the influence of absorbing aerosols results also in decreased optical depth. As at the same time the cloud fraction does not decrease under aerosol influence, the statistical decrease of mean

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

    PubMed

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

    2011-12-15

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

  8. Lidar Observation of the 2014 Kelut Volcanic Stratospheric Aerosols at Kototabang, Indonesia

    NASA Astrophysics Data System (ADS)

    Abo, Makoto; Shibata, Yasukuni; Nagasawa, Chikao

    2016-06-01

    The Kelut (Kelud) volcano (7.9S, 112.3E) in the Java island of Indonesia erupted on 13 February 2014. The CALIOP observed that the eruption cloud reached 26km above sea level. We have observed this stratospheric aerosol from 28 February 2014 at equatorial lidar site located in the Sumatra island of Indonesia (0.2S, 100.3E). We observed the depolarization maximum to be up to 2km below the backscatter maximum in April 2014. We also observed the vertical transportation process of stratospheric aerosol to troposphere by equatorial Kelvin wave.

  9. Strong aerosol-cloud interaction in altocumulus during updraft periods: lidar observations over central Europe

    NASA Astrophysics Data System (ADS)

    Schmidt, J.; Ansmann, A.; Bühl, J.; Wandinger, U.

    2015-09-01

    For the first time, a liquid-water cloud study of the aerosol-cloud-dynamics relationship, solely based on lidar, was conducted. Twenty-nine cases of pure liquid-water altocumulus layers were observed with a novel dual-field-of-view Raman lidar over the polluted central European site of Leipzig, Germany, between September 2010 and September 2012. By means of the novel Raman lidar technique, cloud properties such as the droplet effective radius and cloud droplet number concentration (CDNC) in the lower part of altocumulus layers are obtained. The conventional aerosol Raman lidar technique provides the aerosol extinction coefficient (used as aerosol proxy) below cloud base. A collocated Doppler lidar measures the vertical velocity at cloud base and thus updraft and downdraft occurrence. Here, we present the key results of our statistical analysis of the 2010-2012 observations. Besides a clear aerosol effect on cloud droplet number concentration in the lower part of the altocumulus layers during updraft periods, turbulent mixing and entrainment of dry air is assumed to be the main reason for the found weak correlation between aerosol proxy and CDNC higher up in the cloud. The corresponding aerosol-cloud interaction parameter based on changes in cloud droplet number concentration with aerosol loading was found to be close to 0.8 at 30-70 m above cloud base during updraft periods and below 0.4 when ignoring vertical-wind information in the analysis. Our findings are extensively compared with literature values and agree well with airborne observations.

  10. Aerosol variability and atmospheric transport in the Himalayan region from CALIOP 2007-2010 observations

    NASA Astrophysics Data System (ADS)

    Bucci, S.; Cagnazzo, C.; Cairo, F.; Di Liberto, L.; Fierli, F.

    2014-05-01

    This work quantifies the spatial distribution of different aerosol types, their seasonal variability and sources.The analysis of four years of CALIOP (Cloud-Aerosol LIdar with Orthogonal Polarization) vertically resolved aerosol data allows the identification of spatial patterns of desert dust and carbonaceous particles in different atmospheric layers. Clusters of Lagrangian back trajectories highlight the transport pathways from source regions during the dusty spring season. The analysis shows a prevalence of dust; at low heights it occurs frequently (up to 70% of available observations) and is distributed north of the Tibetan Plateau with a main contribution from the Gobi and Taklamakan deserts, and west of the Tibetan Plateau, originating from the deserts of southwest Asia and advected by the Westerlies. Above the Himalayas the dust amount is minor but still not negligible (occurrence around 20%) and mainly affected by the transport from more distant deserts sources (Sahara and Arabian Peninsula). Carbonaceous aerosol, produced mainly in northern India and eastern China, is subject to shorter-range transport and is indeed observed closer to the sources, while there is a limited amount reaching the top of the plateau. Data analysis reveals a clear seasonal variability in the frequencies of occurrence for the main aerosol types; dust is regulated principally by the monsoon dynamics, with maximal occurrence in spring. We also highlight relevant interannual differences, showing a larger presence of aerosol in the region during 2007 and 2008. The characterization of the aerosol spatial and temporal distribution in terms of observational frequency is a key piece of information that can be directly used for the evaluation of global aerosol models.

  11. Impacts of aerosol scattering on the short-wave infrared satellite observations of CO2

    NASA Astrophysics Data System (ADS)

    Fan, M.; Chen, L.; Li, S.; Tao, J.; Su, L.; Zou, M.

    2014-12-01

    Atmospheric aerosols and carbon dioxide (CO2), as two key factors driving the global climate change, have earned enormous attention from scientist around the world. One challenge for the satellite measurements of CO2 using this SWIR wavelength range (~1.6μm) is the impact of multiple scattering by aerosols and cirrus. Since the rapid economic growth and associated increase in fossil fuel consumption have caused serious particulate pollution in many regions of China, remote sensing of CO2 using SWIR band in China needs to pay more attention to the scattering properties of aerosol particles and the multiple scattering. Considering the complexity of morphological and chemical properties, aerosol particles are grouped based on a large number of TEM/SEM images, and then their scattering properties at 1.6μm band are calculated by the T-matrix method and GMM method. In this study, the Monte Carlo method is used to solve the multiple scattering problem by simulating photons transport in the scattering media. We combined this multiple scattering model with the LBLRTM as a forward radiative transfer model for studying the impact of aerosol scattering on the satellite observations of CO2 using SWIR band. Finally, based on the GOCART aerosol component products, AERONET aerosol size distribution products, CALIPSO aerosol profile products, and MODIS aerosol optical depth and surface albedo products, the monthly variability of errors in CO2 concentrations over China were calculated and analyzed. The results indicate that CO2 concentrations are overestimated in western regions of China, especially in desert areas (a maximum of ~7.08%), and those are underestimated in eastern regions (a minimum of ~-6.9%).

  12. Improvements to the OMI Near-uv Aerosol Algorithm Using A-train CALIOP and AIRS Observations

    NASA Technical Reports Server (NTRS)

    Torres, O.; Ahn, C.; Zhong, C.

    2014-01-01

    The height of desert dust and carbonaceous aerosols layers and, to a lesser extent, the difficulty in assessing the predominant size mode of these absorbing aerosol types, are sources of uncertainty in the retrieval of aerosol properties from near UV satellite observations. The availability of independent, near-simultaneous measurements of aerosol layer height, and aerosol-type related parameters derived from observations by other A-train sensors, makes possible the direct use of these parameters as input to the OMI (Ozone Monitoring Instrument) near UV retrieval algorithm. A monthly climatology of aerosol layer height derived from observations by the CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) sensor, and real-time AIRS (Atmospheric Infrared Sounder) CO observations are used in an upgraded version of the OMI near UV aerosol algorithm. AIRS CO measurements are used as a reliable tracer of carbonaceous aerosols, which allows the identification of smoke layers in areas and times of the year where the dust-smoke differentiation is difficult in the near-UV. The use of CO measurements also enables the identification of elevated levels of boundary layer pollution undetectable by near UV observations alone. In this paper we discuss the combined use of OMI, CALIOP and AIRS observations for the characterization of aerosol properties, and show a significant improvement in OMI aerosol retrieval capabilities.

  13. CALIPSO and MODIS Observations of Increases in Aerosol Optical Depths near Marine Stratocumulus

    NASA Astrophysics Data System (ADS)

    Coakley, J. A.; Tahnk, W. R.

    2009-12-01

    Aerosols not only affect droplet sizes and number concentrations in marine stratocumulus but in turn the near cloud environment gives rise to changes in the aerosol particle concentrations and sizes. In addition, the clouds serve as reflectors that illuminate the adjacent cloud-free air. This extra illumination leads to overestimates of aerosol optical depths and fine mode fractions retrieved from multispectral satellite imagery. Large cloud-free ocean regions bounded on both ends, or if sufficiently large (>100 km), on at least one end by layers of marine stratocumulus, as deduced from CALIPSO lidar returns, were examined to deduce the effects of the clouds on the properties of nearby aerosols. CALIPSO aerosol optical depths composited for more than a year and covering the global oceans, 60°S-60°N, reveal that the fractional increase in aerosol optical depth in going from a cloud-free 5-km region more than 10 to 15 km from a cloud boundary to one adjacent the clouds is 10%-15% at both 532 and 1064 nm for both daytime and nighttime observations. All of the changes are statistically significant at the 90% confidence level or greater. The associated reduction in the 532/1064 Ånsgtröm Exponent is 0.023 for the nighttime observations, but owing to a poorer signal to noise ratio, no change in the Exponent is detected for the daytime observations. For comparison, the MODIS aerosol optical depths collocated with the daytime CALIPSO optical depths suggest that the fractional increases in aerosol optical depths in going from a cloud-free 10-km region 15 km from a cloud boundary to one adjacent the clouds is about 5% at both 550 and 850 nm. The associated reduction in the 550/850 Ånsgtröm Exponent is 0.053. The changes in aerosol properties die away within 10 to 20 km from the marine stratocumulus. The increases in aerosol scattering and reductions in Ånsgtröm Exponent suggest that near the clouds, the aerosol particles become larger. The fine mode fraction found in

  14. Observational Evidence of Impacts of Aerosols on Seasonal-to-Interannual Variability of the Asian Monsoon

    NASA Technical Reports Server (NTRS)

    Lau, K.-M.; Kim, K.-M.; Hsu, N. C.

    2006-01-01

    Observational evidences are presented showing that the Indian subcontinent and surrounding regions are subject to heavy loading of absorbing aerosols (dust and black carbon), with strong seasonality closely linked to the monsoon annual rainfall cycle. Increased loading of absorbing aerosols over the Indo-Gangetic Plain in April-May is associated with a) increased heating of the upper troposphere over the Tibetan Plateau, b) an advance of the monsoon rainy season, and c) subsequent enhancement of monsoon rainfall over the South Asia subcontinent, and reduction over East Asia. Also presented are radiative transfer calculations showing how differential solar absorption by aerosols over bright surface (desert or snow cover land) compared to dark surface (vegetated land and ocean), may be instrumental in triggering an aerosol-monsoon large-scale circulation and water cycle feedback, consistent with the elevated heat pump hypothesis (Lau et al. 2006).

  15. Ground-based lidar observations of ozone aerosol and temperature

    SciTech Connect

    Heaps, W.S.

    1987-09-01

    Several theories have been proposed to explain the recently discovered, springtime ozone depletion over Antarctica, but additional data is necessary to establish what processes are producing this phenomenon. The preliminary results of the 1986-1987 National Ozone Expedition indicate that nitrogen oxides were present smaller amounts than anticipated and that chlorine compounds were more prevalent. These findings support chemical theories based on chlorine or chlorine-bromine chemical mechanisms are affecting the level of ozone in the stratosphere; however, not all climate dynamic theories are discounted by these data. The objective is to use a ground-based laser radar system (lidar) in an upward-looking mode to record ozone profiles, aerosol content, and temperature profiles. Although the system was not principally designed for these measurements, the author has modified it slightly to collect these data.

  16. Evaluating Clouds, Aerosols, and their Interactions in Three Global Climate Models using COSP and Satellite Observations

    SciTech Connect

    Ban-Weiss, George; Jin, Ling; Bauer, S.; Bennartz, Ralph; Liu, Xiaohong; Zhang, Kai; Ming, Yi; Guo, Huan; Jiang, Jonathan

    2014-09-23

    Accurately representing aerosol-cloud interactions in global climate models is challenging. As parameterizations evolve, it is important to evaluate their performance with appropriate use of observations. In this work we compare aerosols, clouds, and their interactions in three climate models (AM3, CAM5, ModelE) to MODIS satellite observations. Modeled cloud properties were diagnosed using the CFMIP Observations Simulator Package (COSP). Cloud droplet number concentrations (N) were derived using the same algorithm for both satellite-simulated model values and observations. We find that aerosol optical depth tau simulated by models is similar to observations. For N, AM3 and CAM5 capture the observed spatial pattern of higher values in near-coast versus remote ocean regions, though modeled values in general are higher than observed. In contrast, ModelE simulates lower N in most near-coast versus remote regions. Aerosol- cloud interactions were computed as the sensitivity of N to tau for marine liquid clouds off the coasts of South Africa and Eastern Asia where aerosol pollution varies in time. AM3 and CAM5 are in most cases more sensitive than observations, while the sensitivity for ModelE is statistically insignificant. This widely used sensitivity could be subject to misinterpretation due to the confounding influence of meteorology on both aerosols and clouds. A simple framework for assessing the N – tau sensitivity at constant meteorology illustrates that observed sensitivity can change from positive to statistically insignificant when including the confounding influence of relative humidity. Satellite simulated values of N were compared to standard model output and found to be higher with a bias of 83 cm-3.

  17. Vertical Distribution of Dust and Water Ice Aerosols from CRISM Limb-geometry Observations

    NASA Technical Reports Server (NTRS)

    Smith, Michael Doyle; Wolff, Michael J.; Clancy, Todd; Kleinbohl, Armin; Murchie, Scott L.

    2013-01-01

    [1] Near-infrared spectra taken in a limb-viewing geometry by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) on board the Mars Reconnaissance Orbiter provide a useful tool for probing atmospheric structure. Specifically, the observed radiance as a function of wavelength and height above the limb enables the vertical distribution of both dust and water ice aerosols to be retrieved. More than a dozen sets of CRISM limb observations have been taken so far providing pole-to-pole cross sections, spanning more than a full Martian year. Radiative transfer modeling is used to model the observations taking into account multiple scattering from aerosols and the spherical geometry of the limb observations. Both dust and water ice vertical profiles often show a significant vertical structure for nearly all seasons and latitudes that is not consistent with the well-mixed or Conrath-v assumptions that have often been used in the past for describing aerosol vertical profiles for retrieval and modeling purposes. Significant variations are seen in the retrieved vertical profiles of dust and water ice aerosol as a function of season. Dust typically extends to higher altitudes (approx. 40-50km) during the perihelion season than during the aphelion season (<20km), and the Hellas region consistently shows more dust mixed to higher altitudes than other locations. Detached water ice clouds are common, and water ice aerosols are observed to cap the dust layer in all seasons.

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

    NASA Technical Reports Server (NTRS)

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

    2015-01-01

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

  19. Fog Induced Aerosol Modification Observed by AERONET, Including Occurrences During Major Air Pollution Events

    NASA Astrophysics Data System (ADS)

    Eck, T. F.; Holben, B. N.; Reid, J. S.; Giles, D. M.; Rivas, M.; Singh, R. P.; Tripathi, S. N.; Bruegge, C. J.; Li, Z.; Platnick, S. E.; Arnold, T.; Ferrare, R. A.; Hostetler, C. A.; Burton, S. P.; Kim, J.; Kim, Y. J.; Sinyuk, A.; Dubovik, O.; Arola, A. T.; Schafer, J.; Artaxo, P.; Smirnov, A.; Chen, H.; Goloub, P.

    2014-12-01

    The modification of aerosol optical properties due to interaction with fog is examined from measurements made by sun/sky radiometers at several AERONET sites. Retrieved total column volume size distributions for cases identified as aerosol modified by fog often show very a large 'middle mode' submicron radius (~0.4 to 0.5 microns), which is typically seen as a component of a bimodal sub-micron distribution. These middle mode sized particles are often called cloud-processed or residual aerosol. This bimodal accumulation mode distribution may be due to one mode (the larger one) from fog-processed aerosol and the other from interstitial aerosol, or possibly from two different aerosol species (differing chemical composition) with differing hygroscopic growth factors. The size of the fine mode particles from AERONET retrieved for these cases exceeds the size of sub-micron sized particles retrieved for nearly all other aerosol types, suggesting significant modification of aerosols within the fog or cloud environment. In-situ measured aerosol size distributions made during other fog events are compared to the AERONET retrievals, and show close agreement in the residual mode particle size. Almucantar retrievals are analyzed from the Kanpur site in the Indo-Gangetic Plain in India (fog in January), Beijing (fog in winter), Fresno, CA in the San Joaquin Valley (fog in winter), South Korea (Yellow Sea fog in spring), Arica on the northern coast of Chile (stratocumulus), and several other sites with aerosol observations made after fog dissipated. Additionally, several major air pollution events are discussed where extremely high aerosol concentrations were measured at the surface and during which fog also occurred, resulting in the detection very large fine mode aerosols (residual mode) from AERONET retrievals in some of these events. Low wind speeds that occurred during these events were conducive to both pollutant accumulation and also fog formation. The presence of fog then

  20. Fog Induced Aerosol Modification Observed by AERONET, Including Occurrences During Major Air Pollution Events

    NASA Astrophysics Data System (ADS)

    Eck, T. F.; Holben, B. N.; Reid, J. S.; Giles, D. M.; Rivas, M.; Singh, R. P.; Tripathi, S. N.; Bruegge, C. J.; Li, Z.; Platnick, S. E.; Arnold, T.; Ferrare, R. A.; Hostetler, C. A.; Burton, S. P.; Kim, J.; Kim, Y. J.; Sinyuk, A.; Dubovik, O.; Arola, A. T.; Schafer, J.; Artaxo, P.; Smirnov, A.; Chen, H.; Goloub, P.

    2015-12-01

    The modification of aerosol optical properties due to interaction with fog is examined from measurements made by sun/sky radiometers at several AERONET sites. Retrieved total column volume size distributions for cases identified as aerosol modified by fog often show very a large 'middle mode' submicron radius (~0.4 to 0.5 microns), which is typically seen as a component of a bimodal sub-micron distribution. These middle mode sized particles are often called cloud-processed or residual aerosol. This bimodal accumulation mode distribution may be due to one mode (the larger one) from fog-processed aerosol and the other from interstitial aerosol, or possibly from two different aerosol species (differing chemical composition) with differing hygroscopic growth factors. The size of the fine mode particles from AERONET retrieved for these cases exceeds the size of sub-micron sized particles retrieved for nearly all other aerosol types, suggesting significant modification of aerosols within the fog or cloud environment. In-situ measured aerosol size distributions made during other fog events are compared to the AERONET retrievals, and show close agreement in the residual mode particle size. Almucantar retrievals are analyzed from the Kanpur site in the Indo-Gangetic Plain in India (fog in January), Beijing (fog in winter), Fresno, CA in the San Joaquin Valley (fog in winter), South Korea (Yellow Sea fog in spring), Arica on the northern coast of Chile (stratocumulus), and several other sites with aerosol observations made after fog dissipated. Additionally, several major air pollution events are discussed where extremely high aerosol concentrations were measured at the surface and during which fog also occurred, resulting in the detection very large fine mode aerosols (residual mode) from AERONET retrievals in some of these events. Low wind speeds that occurred during these events were conducive to both pollutant accumulation and also fog formation. The presence of fog then

  1. Comparison of Columnar Water Vapor Measurements During The Fall 1997 ARM Intensive Observation Period: Optical Methods

    NASA Technical Reports Server (NTRS)

    Schmid, Beat; Michalsky, J.; Slater, D.; Barnard, J.; Halthore, R.; Liljegren, J.; Holben, B.; Eck, T.; Livingston, J.; Russell, P.; Hipskind, R. Stephen (Technical Monitor)

    2000-01-01

    In the fall of 1997 the Atmospheric Radiation Measurement (ARM program conducted an intensive Observation Period (IOP) to study water vapor at its Southern Great Plains (SGP) site. Among the large number of instruments, four sun-tracking radiometers were present to measure the columnar water vapor (CWV). All four solar radiometers retrieve CWV by measuring solar transmittance in the 0.94-micrometer water vapor absorption band. As one of the steps in the CWV retrievals the aerosol component is subtracted from the total transmittance, in the 0.94-micrometer band. The aerosol optical depth comparisons among the same four radiometers are presented elsewhere. We have used three different methods to retrieve CWV. Without attempting to standardize on the same radiative transfer model and its underlying water vapor spectroscopy we found the CWV to agree within 0.13 cm (rms) for CWV values ranging from 1 to 5 cm. Preliminary results obtained when using the same updated radiative transfer model with updated spectroscopy for all instruments will also be shown. Comparisons to the microwave radiometer results will be included in the comparisons.

  2. Systematic Satellite Observations of the Impact of Aerosols from Passive Volcanic Degassing on Local Cloud Properties

    NASA Technical Reports Server (NTRS)

    Ebmeier, S.K.; Sayer, Andrew M.; Grainger, R. G.; Mather, T. A.; Carboni, E.

    2014-01-01

    The impact of volcanic emissions, especially from passive degassing and minor explosions, is a source of uncertainty in estimations of aerosol indirect effects. Observations of the impact of volcanic aerosol on clouds contribute to our understanding of both present-day atmospheric properties and of the pre-industrial baseline necessary to assess aerosol radiative forcing. We present systematic measurements over several years at multiple active and inactive volcanic islands in regions of low present-day aerosol burden. The timeaveraged indirect aerosol effects within 200 kilometers downwind of island volcanoes are observed using Moderate Resolution Imaging Spectroradiometer (MODIS, 2002-2013) and Advanced Along-Track Scanning Radiometer (AATSR, 2002- 2008) data. Retrievals of aerosol and cloud properties at Kilauea (Hawaii), Yasur (Vanuatu) and Piton de la Fournaise (la Reunion) are rotated about the volcanic vent to be parallel to wind direction, so that upwind and downwind retrievals can be compared. The emissions from all three volcanoes - including those from passive degassing, Strombolian activity and minor explosions - lead to measurably increased aerosol optical depth downwind of the active vent. Average cloud droplet effective radius is lower downwind of the volcano in all cases, with the peak difference ranging from 2 - 8 micrometers at the different volcanoes in different seasons. Estimations of the difference in Top of Atmosphere upward Short Wave flux upwind and downwind of the active volcanoes from NASA's Clouds and the Earth's Radiant Energy System (CERES) suggest a downwind elevation of between 10 and 45 Watts per square meter at distances of 150 - 400 kilometers from the volcano, with much greater local (less than 80 kilometers) effects. Comparison of these observations with cloud properties at isolated islands without degassing or erupting volcanoes suggests that these patterns are not purely orographic in origin. Our observations of unpolluted

  3. Systematic satellite observations of the impact of aerosols from passive volcanic degassing on local cloud properties

    NASA Astrophysics Data System (ADS)

    Ebmeier, S. K.; Sayer, A. M.; Grainger, R. G.; Mather, T. A.; Carboni, E.

    2014-10-01

    The impact of volcanic emissions, especially from passive degassing and minor explosions, is a source of uncertainty in estimations of aerosol indirect effects. Observations of the impact of volcanic aerosol on clouds contribute to our understanding of both present-day atmospheric properties and of the pre-industrial baseline necessary to assess aerosol radiative forcing. We present systematic measurements over several years at multiple active and inactive volcanic islands in regions of low present-day aerosol burden. The time-averaged indirect aerosol effects within 200 km downwind of island volcanoes are observed using Moderate Resolution Imaging Spectroradiometer (MODIS, 2002-2013) and Advanced Along-Track Scanning Radiometer (AATSR, 2002-2008) data. Retrievals of aerosol and cloud properties at Kīlauea (Hawai'i), Yasur (Vanuatu) and Piton de la Fournaise (la Réunion) are rotated about the volcanic vent to be parallel to wind direction, so that upwind and downwind retrievals can be compared. The emissions from all three volcanoes - including those from passive degassing, Strombolian activity and minor explosions - lead to measurably increased aerosol optical depth downwind of the active vent. Average cloud droplet effective radius is lower downwind of the volcano in all cases, with the peak difference ranging from 2-8 μm at the different volcanoes in different seasons. Estimations of the difference in Top of Atmosphere upward Short Wave flux upwind and downwind of the active volcanoes from NASA's Clouds and the Earth's Radiant Energy System (CERES) suggest a downwind elevation of between 10 and 45 Wm-2 at distances of 150-400 km from the volcano, with much greater local (< 80 km) effects. Comparison of these observations with cloud properties at isolated islands without degassing or erupting volcanoes suggests that these patterns are not purely orographic in origin. Our observations of unpolluted, isolated marine settings may capture processes similar to

  4. Organic Mass to Organic Carbon ratio in Atmospheric Aerosols: Observations and Global Simulations

    NASA Astrophysics Data System (ADS)

    Tsigaridis, K.; Kanakidou, M.; Daskalakis, N.

    2012-12-01

    Organic compounds play an important role in atmospheric chemistry and affect Earth's climate through their impact on oxidants and aerosol formation (e.g. O3 and organic aerosols (OA)). Due to the complexity of the mixture of organics in the atmosphere, the organic-mass-to-organic-carbon ratio (OM/OC) is often used to characterize the organic component in atmospheric aerosols. This ratio varies dependant on the aerosol origin and the chemical processing in the atmosphere. Atmospheric observations have shown that as OA and its precursor gases age in the atmosphere, it leads to the formation of more oxidized (O:C atomic ratio 0.6 to 0.8), less volatile and less hydrophobic compounds (particle growth factor at 95% relative humidity of 0.16 to 0.20) that have more similar properties than fresh aerosols. While reported OM:OC ratios observed over USA range between 1.29 and 1.95, indicating significant contribution of local pollution sources to the OC in that region, high O/C ratio associated with a high OM/OC ratio of 2.2 has been also observed for the summertime East Mediterranean aged aerosol. In global models, the OM/OC ratio is either calculated for specific compounds or estimated for compound groups. In the present study, we review OM/OC observations and compare them with simulations from a variety of models that contributed to the AEROCOM exercise. We evaluate the chemical processing level of atmospheric aerosols simulated by the models. A total of 32 global chemistry transport models are considered in this study with variable complexity of the representation of OM/OC ratio in the OA. The analysis provides an integrated view of the OM/OC ratio in the global atmosphere and of the accuracy of its representation in the global models. Implications for atmospheric chemistry and climate simulations are discussed.

  5. Investigation of the Impact of Aerosols on Clouds During May 2003 Intensive Operational Period at the Southern Great Plains

    SciTech Connect

    Guo, H.; Penner, J.E.; Herzog, M.

    2005-03-18

    The effect of aerosols on the clouds, or the so-called aerosol indirect effect (AIE), is highly uncertain (Penner et al. 2001). The estimation of the AIE can vary from 0.0 to -4.8 W/m2 in Global Climate Models (GCM). Therefore, it is very important to investigate these interactions and cloud-related physical processes further. The Aerosol Intensive Operation Period (AIOP) at the Southern Great Plains (SGP) site in May 2003 dedicated some effort towards the measurement of the Cloud Condensation Nucleus concentration (CCN) as a function of super-saturation and in relating CCN concentration to aerosol composition and size distribution. Furthermore, airborn measurement for the cloud droplet concentration was also available. Therefore this AIOP provides a good opportunity to examine the AIE. In this study, we use a Cloud Resolving Model (CRM), i.e., Active Tracer High-resolution Atmospheric Model (ATHAM), to discuss the effect of aerosol loadings on cloud droplet effective radius (Re) and concentration. The case we examine is a stratiform cloud that occurred on May 17, 2003.

  6. Use of Observation-Based Aerosol Fields for Detailed Cloud-Scale Modeling Studies

    NASA Astrophysics Data System (ADS)

    Fridlind, A. M.; Vogelmann, A. M.; Ackerman, A. S.; Endo, S.

    2014-12-01

    Within the realm of detailed large-eddy simulation studies with size-resolved microphysics, substantial uncertainties exist regarding the ability of any given model to accurately reproduce basic aspects of cloud microphysics that interact with ambient aerosol properties, such as precipitation formation and evolution. Modeling studies intended to reproduce specific observed cloud fields must also to some degree simplify the complexity of aerosol conditions, and usually lack sufficient measurements to well constrain the most relevant aerosol properties. Here we describe derivation and use of spatiotemporally varying fields of multi-modal aerosol size distributions for 60-hour simulations of boundary-layer clouds observed over Oklahoma during the RACORO campaign. Cases include forced as well as freely convecting shallow clouds, and some warm precipitation. We investigate the sensitivity of simulations to observation-derived aerosol inputs, including hygroscopicity parameter and size distribution properties. Sensitivity is examined in the context of the ability of the simulations to accurately reproduce relevant macrophysical and microphysical cloud properties observed, including droplet size dispersion.

  7. Combined observational and modeling efforts of aerosol-cloud-precipitation interactions over Southeast Asia

    NASA Astrophysics Data System (ADS)

    Loftus, Adrian; Tsay, Si-Chee; Nguyen, Xuan Anh

    2016-04-01

    droplet size and number concentration, but also the spectral width of the cloud droplet size distribution, the 3M scheme is well suited to simulate aerosol-cloud-precipitation interactions within a three-dimensional regional cloud model. Moreover, the additional variability predicted on the hydrometeor distributions provides beneficial input for forward models to link the simulated microphysical processes with observations as well as to assess both ground-based and satellite retrieval methods. In this presentation, we provide an overview of the 7 South East Asian Studies / Biomass-burning Aerosols and Stratocumulus Environment: Lifecycles and Interactions Experiment (7-SEAS/BASELInE) operations during the spring of 2013. Preliminary analyses of pre-monsoon Sc system lifecycles observed during the first-ever deployment of a ground-based cloud radar to northern Vietnam will be also be presented. Initial results from GCE model simulations of these Sc using double-moment and the new 3M bulk microphysics schemes under various aerosol loadings will be used to showcase the 3M scheme as well as provide insight into how the impact of aerosols on cloud and precipitation processes in stratocumulus over land may manifest themselves in simulated remote-sensing signals. Applications and future work involving ongoing 7-SEAS campaigns aimed at improving our understanding of aerosol-cloud-precipitation interactions of will also be discussed.

  8. DEPOSITION OF SULFATE ACID AEROSOLS IN THE DEVELOPING HUMAN LUNG

    EPA Science Inventory

    Computations of aerosol deposition as affected by (i) aerosol hygroscopicity, (ii) human age, and (iii) respiratory intensity are accomplished using a validated mathematical model. he interactive effects are very complicated but systematic. ew general observations can be made; ra...

  9. An Intensive Study of Aerosol Optical Properties in the Outflow of the Manaus Urban Plume, in Central Amazon

    NASA Astrophysics Data System (ADS)

    Artaxo, P.; Cirino, G. G.; Brito, J.; Rizzo, L. V.; Barbosa, H. M.; Carbone, S.; Holanda, B. A.; Souza, R. A. F. D.; Tota, J.; Martin, S. T.

    2015-12-01

    In this study, one year of ground-based observations of aerosol optical properties from a site impacted by urban emissions in Central Amazon of Brazil are assessed as part of results from GoAmazon2014/5 experiment. The aerosol absorption (σa) and scattering (σs) coefficients, as well as single scattering albedo (SSA) are analyzed to aid in characterizing Manaus' urban aerosol at GoAmazon T2 site. There is a distinct diurnal variation for (σa) it was mainly attributed to the severe emission of particulate pollutants and black carbon during the morning and evening traffic rush hours. The decrease of (σa) nearly at noon (12:00-14:00 LT) was a result of strong atmospheric mixing and dilution due to the elevated height of atmospheric planetary boundary layer (PBL). After sunset (18:00 LT), the formation of stable nocturnal PBL even in atmospheric inversion led to a low atmospheric diffusion ability to aerosols and thus relatively high (σa) and (σs) throughout the night. Indeed, it was observed a strong dependence on local wind confirmed by simulated back trajectories in all two seasons. Overall, the wind dependence results provide valuable information about the locations of aerosol pollution sources and suggest that the air pollution in dry season is a regional problem but in the wet season it is mainly affected by local urban emissions. We have also seen an interesting difference in variability of (σs) and (σa) during 8:00-13:00 LT in wet season. A clear decrease was observed for (σa), while a smooth increase during 11:00-13:00 LT was presented for (σs). This is possibly a consequence of secondary aerosol production. (σa) is controlled to a large degree by primary aerosols such as black carbon that are emitted directly from pollution sources like vehicles, while (σs) is related to secondary aerosols such as sulfate and nitrate that contribute the most to light scattering. SSA was relatively low around 7:00-08:00 LT, which reflected that (σa) increased more

  10. On the reliability of geostationary satellite observations for diagnosing indirect aerosol effects

    NASA Astrophysics Data System (ADS)

    Merk, Daniel; Deneke, Hartwig; Pospichal, Bernhard; Seifert, Patric

    2015-10-01

    Aerosol indirect effects are poorly understand and constitute a highly uncertain anthropogenic forcing of climate change. The interaction of aerosols with clouds together with entrainment and turbulent mixing processes modulate cloud microphysics and radiative effects. In the current study we present preliminary results to diagnose indirect aerosol effects from the synergy of geostationary satellite observations, surface observations and MACC aerosol analysis. We examine if the sub-adiabatic factor - representative for entrainment - can be obtained from the combination of passive-satellite observations with ground-based cloud base height from a ceilometer network. Therefore the uncertainty of the sub-adiabatic factor due to its required input parameters, the cloud geometrical thickness and liquid water path, is explored. We use a two year dataset from SEVIRI and compare it to the LACROS supersite at Leipzig, Germany. We find that the comparison of satellite-retrieved cloud top heights shows a RMSD of 1100 m and the liquid water path of 75 gm-2, which are too large to provide a meaningful estimate of the instantaneous sub-adiabtic factor. Linking the cloud microphysical properties from passive satellites with aerosol properties obtained from MACC, we investigate the Twomey hypothesis, namely that smaller droplets and a higher cloud droplet number concentration result from higher aerosol load for a given liquid water path (positive change). A positive relative change is obtained for aerosol optical depth and the sulphate mass integrated from the surface to the cloud top. In contrast, a negative relative change is however found for sea salt.

  11. Comparing regional modeling (CHIMERE) and satellite observations of aerosols (PARASOL): Methodology and case study over Mexico

    NASA Astrophysics Data System (ADS)

    Stromatas, Stavros

    2010-05-01

    S. Stromatas (1), S. Turquety (1), H. Chepfer (1), L. Menut (1), B. Bessagnet (2), JC Pere (2), D. Tanré (3) . (1) Laboratoire de Météorologie Dynamique, CNRS/IPSL, École Polytechnique, 91128 Palaiseau Cedex, France, (2) INERIS, Institut National de l'Environnement Industriel et des Risques, Parc technologique ALATA, 60550 Verneuil en Halatte, FRANCE, (3) Laboratoire d'Optique Atmosphérique/CNRS Univ. des Sciences et Tech. de Lille, 59650 - Villeneuve d'Ascq, France. Atmospheric suspended particles (aerosols) have significant radiative and environmental impacts, affecting human health, visibility and climate. Therefore, they are regulated by air quality standards worldwide, and monitored by regional observation networks. Satellite observations vastly improve the horizontal and temporal coverage, providing daily distributions. Aerosols are currently estimated using aerosol optical depth (AOD) retrievals, a quantitative measure of the extinction of solar radiation by aerosol scattering and absorption between the point of observation and the top of the atmosphere. Even though remarkable progresses in aerosol modeling by chemistry-transport models (CTM) and measurement experiments have been made in recent years, there is still a significant divergence between the modeled and observed results. However, AOD retrievals from satellites remains a highly challenging task mostly because it depends on a variety of different parameters such as cloud contamination, surface reflectance contributions and a priori assumptions on aerosol types, each one of them incorporating its own difficulties. Therefore, comparisons between CTM and observations are often difficult to interpret. In this presentation, we will discuss comparisons between regional modeling (CHIMERE CTM) over Mexico and satellite observations obtained by the POLDER instrument embarked on PARASOL micro-satellite. After a comparison of the model AOD with the retrieved L2 AOD, we will present an alternative

  12. Chemical Composition and Size Distributions of Coastal Aerosols Observed on the U.S. East Coast

    NASA Astrophysics Data System (ADS)

    Xia, L.; Song, F.; Jusino-Atresino, R.; Thuman, C.; Gao, Y.

    2008-12-01

    Aerosol input is an important source of certain limiting nutrients, such as iron, for phytoplankton growth in several large oceanic regions. As the efficiency of biological uptake of nutrients may depend on the aerosol properties, a better knowledge of aerosol properties is critically important. Characterizing aerosols over the coastal ocean needs special attention, because the properties of aerosols could be altered by many anthropogenic processes in this land-ocean transition zone before they are transported over the remote ocean. The goal of this experiment was to examine aerosol properties, in particular chemical composition, particle-size distributions and iron solubility, over the US Eastern Seaboard, an important boundary for the transport of continental substances from North America to the North Atlantic Ocean. Our field sampling site was located at Tuckerton (39°N, 74°W) on the southern New Jersey coast. Fourteen sets of High-Volume aerosol samples and three sets of size segregated aerosol samples by a 10-stage MOUDI impactor were collected during 2007 and 2008. The ICP-MS methodology was used to analyze aerosol samples for the concentrations of thirteen trace elements: Al, Fe, Mn, Sc, Cd, Pb, Sb, Ni, Co, Cr, Cu, Zn and V. The IC procedures were applied to determine five cations (sodium, ammonium, potassium, magnesium and calcium) and eleven anions (fluoride, acetate, propionate, formate, MSA, chloride, nitrate, succinate, malonate, sulfate and oxalate). The UV spectrometry was employed for the determination of iron solubility. Preliminary results suggest three major sources of aerosols: anthropogenic, crustal and marine. At this location, the concentrations of iron (II) ranged from 2.8 to 29ng m-3, accounting for ~20% of the total iron. The iron concentrations at this coastal site were substantially lower than those observed in Newark, an urban site in northern NJ. High concentrations of iron (II) were associated with both fine and coarse aerosol

  13. Aerosol observations and growth rates downwind of the anvil of a deep tropical thunderstorm

    NASA Astrophysics Data System (ADS)

    Waddicor, D. A.; Vaughan, G.; Choularton, T. W.; Bower, K. N.; Coe, H.; Gallagher, M.; Williams, P. I.; Flynn, M.; Volz-Thomas, A.; Pätz, H.-W.; Isaac, P.; Hacker, J.; Arnold, F.; Schlager, H.; Whiteway, J. A.

    2012-07-01

    We present a case study of Aitken and accumulation mode aerosol observed downwind of the anvil of a deep tropical thunderstorm. The measurements were made by condensation nuclei counters flown on the Egrett high-altitude aircraft from Darwin during the ACTIVE campaign, in monsoon conditions producing widespread convection over land and ocean. Maximum measured concentrations of aerosol with diameter greater than 10 nm were 25 000 cm-3 (STP). By calculating back-trajectories from the observations, and projecting onto infrared satellite images, the time since the air exited cloud was estimated. In this way a time scale of about 3 hours was derived for the Aitken aerosol concentration to reach its peak. We examine the hypothesis that the growth in aerosol concentrations can be explained by production of sulphuric acid from SO2 followed by particle nucleation and coagulation. Estimates of the sulphuric acid production rate show that the observations are only consistent with this hypothesis if the particles coagulate to sizes >10 nm much more quickly than is suggested by current theory. Alternatively, other condensible gases (possibly organic) drive the growth of aerosol particles in the TTL.

  14. Evaluation of simulated aerosol properties with the aerosol-climate model ECHAM5-HAM using observations from the IMPACT field campaign

    NASA Astrophysics Data System (ADS)

    Roelofs, G.-J.; ten Brink, H.; Kiendler-Scharr, A.; de Leeuw, G.; Mensah, A.; Minikin, A.; Otjes, R.

    2010-08-01

    In May 2008, the measurement campaign IMPACT for observation of atmospheric aerosol and cloud properties was conducted in Cabauw, The Netherlands. With a nudged version of the coupled aerosol-climate model ECHAM5-HAM we simulate the size distribution and chemical composition of the aerosol and the associated aerosol optical thickness (AOT) for the campaign period. Synoptic scale meteorology is represented realistically through nudging of the vorticity, the divergence, the temperature and the surface pressure. Simulated concentrations of aerosol sulfate and organics at the surface are generally within a factor of two from observed values. The monthly averaged AOT from the model is 0.33, about 20% larger than observed. For selected periods of the month with relatively dry and moist conditions discrepancies are approximately -30% and +15%, respectively. Discrepancies during the dry period are partly caused by inaccurate representation of boundary layer (BL) dynamics by the model affecting the simulated AOT. The model simulates too strong exchange between the BL and the free troposphere, resulting in weaker concentration gradients at the BL top than observed for aerosol and humidity, while upward mixing from the surface layers into the BL appears to be underestimated. The results indicate that beside aerosol sulfate and organics also aerosol ammonium and nitrate significantly contribute to aerosol water uptake. The simulated day-to-day variability of AOT follows synoptic scale advection of humidity rather than particle concentration. Even for relatively dry conditions AOT appears to be strongly influenced by the diurnal cycle of RH in the lower boundary layer, further enhanced by uptake and release of nitric acid and ammonia by aerosol water.

  15. LOCAL AIR: Local Aerosol monitoring combining in-situ and Remote Sensing observations

    NASA Astrophysics Data System (ADS)

    Mona, Lucia; Caggiano, Rosa; Donvito, Angelo; Giannini, Vincenzo; Papagiannopoulos, Nikolaos; Sarli, Valentina; Trippetta, Serena

    2015-04-01

    The atmospheric aerosols have effects on climate, environment and health. Although the importance of the study of aerosols is well recognized, the current knowledge of the characteristics and their distribution is still insufficient, and there are large uncertainties in the current understanding of the role of aerosols on climate and the environment, both on a regional and local level. Overcoming these uncertainties requires a search strategy that integrates data from multiple platforms (eg, terrestrial, satellite, ships and planes) and the different acquisition techniques (for example, in situ measurements, remote sensing, modeling numerical and data assimilation) (Yu et al., 2006). To this end, in recent years, there have been many efforts such as the creation of networks dedicated to systematic observation of aerosols (eg, European Monitoring and Evaluation Programme-EMEP, European Aerosol Research Lidar NETwork-EARLINET, MicroPulse Lidar Network- MPLNET, and Aerosol Robotic NETwork-AERONET), the development and implementation of new satellite sensors and improvement of numerical models. The recent availability of numerous data to the ground, columnar and profiles of aerosols allows to investigate these aspects. An integrated approach between these different techniques could be able to provide additional information, providing greater insight into the properties of aerosols and their distribution and overcoming the limits of each single technique. In fact, the ground measurements allow direct determination of the physico-chemical properties of aerosols, but cannot be considered representative for large spatial and temporal scales and do not provide any information about the vertical profile of aerosols. On the other hand, the remote sensing techniques from the ground and satellite provide information on the vertical distribution of atmospheric aerosols both in the Planetary Boundary Layer (PBL), mainly characterized by the presence of aerosols originating from

  16. CCN frequency distributions and aerosol chemical composition from long-term observations at European ACTRIS supersites

    NASA Astrophysics Data System (ADS)

    Decesari, Stefano; Rinaldi, Matteo; Schmale, Julia Yvonne; Gysel, Martin; Fröhlich, Roman; Poulain, Laurent; Henning, Silvia; Stratmann, Frank; Facchini, Maria Cristina

    2016-04-01

    Cloud droplet number concentration is regulated by the availability of aerosol acting as cloud condensation nuclei (CCN). Predicting the air concentrations of CCN involves knowledge of all physical and chemical processes that contribute to shape the particle size distribution and determine aerosol hygroscopicity. The relevance of specific atmospheric processes (e.g., nucleation, coagulation, condensation of secondary organic and inorganic aerosol, etc.) is time- and site-dependent, therefore the availability of long-term, time-resolved aerosol observations at locations representative of diverse environments is strategic for the validation of state-of-the-art chemical transport models suited to predict CCN concentrations. We focused on long-term (year-long) datasets of CCN and of aerosol composition data including black carbon, and inorganic as well as organic compounds from the Aerosol Chemical Speciation Monitor (ACSM) at selected ACTRIS supersites (http://www.actris.eu/). We discuss here the joint frequency distribution of CCN levels and of aerosol chemical components concentrations for two stations: an alpine site (Jungfraujoch, CH) and a central European rural site (Melpitz, DE). The CCN frequency distributions at Jungfraujoch are broad and generally correlated with the distributions of the concentrations of aerosol chemical components (e.g., high CCN concentrations are most frequently found for high organic matter or black carbon concentrations, and vice versa), which can be explained as an effect of the strong seasonality in the aerosol characteristics at the mountain site. The CCN frequency distributions in Melpitz show a much weaker overlap with the distributions of BC concentrations or other chemical compounds. However, especially at high CCN concentration levels, a statistical correlation with organic matter (OM) concentration can be observed. For instance, the number of CCN (with particle diameter between 20 and 250 nm) at a supersaturation of 0.7% is

  17. Systematic satellite observations of the impact of aerosols from passive volcanic degassing on local cloud properties

    NASA Astrophysics Data System (ADS)

    Ebmeier, S. K.; Mather, T. A.; Sayer, A. M.; Grainger, R. G.; Carboni, E.

    2014-12-01

    Aerosol indirect radiative effects - the alteration of cloud properties by atmospheric aerosol - have a large, but relatively uncertain impact on the Earth's radiative balance. Quantification of volcanic aerosol indirect effects contributes to our understanding of both present-day atmospheric properties and of the pre-industrial baseline necessary to assess aerosol radiative forcing. The impact of emissions from passively degassing volcanoes and minor volcanic explosions are particularly poorly constrained. We present systematic satellite measurements of the time-averaged indirect aerosol effect over several years at multiple active and inactive volcanic islands (Moderate Resolution Imaging Spectroradiometer, 2000-2013 and Advanced Along-Track Scanning Radiometer 2002-2008). Retrievals of aerosol and cloud properties at Kilauea, Yasur and Piton de la Fournaise are rotated about the volcanic vent to be parallel to wind direction, so that average upwind and downwind values can be estimated. The emissions from all three volcanoes, including those from passive degassing, strombolian activity and minor explosions lead to measurably increased aerosol optical depth (<0.1) and decreased cloud droplet effective radius (<8 μm) downwind of the volcanoes. Furthermore, Top of Atmosphere Short Wave flux from NASA's Clouds and the Earth's Radiant Energy System (CERES) show downwind perturbations ranging from 10 to 45 Wm-2 within 400 km of degassing volcanoes. Comparison of these observations to cloud properties at isolated islands without degassing volcanoes demonstrates that these patterns are not purely orographic in origin. Our observations of unpolluted, isolated marine settings may capture processes similar to those in the pre-industrial marine atmosphere.

  18. Comparing the relationships between aerosol optical depth and cloud properties in observations and global models

    NASA Astrophysics Data System (ADS)

    Gryspeerdt, Edward; Quaas, Johannes

    2016-04-01

    Aerosols impact the climate both directly, through their interaction with radiation and indirectly, via their ability to act as cloud condensation nuclei (CCN), modifying cloud properties. The influence of aerosols on cloud properties is highly uncertain. Many relationships between aerosol optical depth (AOD) and cloud properties have been observed using satellite data, but previous work has shown that some of these relationships are the product of the strong AOD-cloud fraction (CF) relationship. The confounding influence of local meteorology obscures the magnitude of any aerosol impact on CF, and so also the impact of aerosol on other cloud properties. For example, both AOD and CF are strongly influenced by relative humidity, which can generate a correlation between them. Previous studies have used reanalysis data to account for confounding meteorological variables. This requires knowledge of the relevant meteorological variables and is limited by the accuracy of the reanalysis data. Recent work has shown that by using the cloud droplet number concentration (CDNC) to mediate the AOD-CF relationship, the impact of relative humidity can be significantly reduced. This method removes the limitations imposed by the finite accuracy of reanalysis data. In this work we investigate the impact of the CDNC mediation on the AOD-CF relationship and on the relationship between AOD and other cloud properties in global atmospheric models. By comparing pre-industrial and present day runs, we investigate the success of the CDNC mediated AOD-CF relationship to predict the change in CF from the pre-industrial to the present day using only observations of the present day relationships between clouds and aerosol properties. This helps to determine whether the satellite-derived relationship provides a constraint on the aerosol indirect forcing due to changes in CF.

  19. 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.

  20. Titan Aerosol Analogs from Aromatic Precursors: Comparisons to Cassini CIRS Observations in the Thermal Infrared

    NASA Technical Reports Server (NTRS)

    Trainer, Melissa G.; Sebree, Joshua A.; Anderson, Carrie M.; Loeffler, Mark J.

    2012-01-01

    Since Cassini's arrival at Titan, ppm levels of benzene (C6H6) as well as large positive ions, which may be polycyclic aromatic hydrocarbons (PAHs). have been detected in the atmosphere. Aromatic molecules. photolytically active in the ultraviolet, may be important in the formation of the organic aerosol comprising the Titan haze layer even when present at low mixing ratios. Yet there have not been laboratory simulations exploring the impact of these molecules as precursors to Titan's organic aerosol. Observations of Titan by the Cassini Composite Infrared Spectrometer (CIRS) in the far-infrared (far-IR) between 560 and 20/cm (approx. 18 to 500 microns) and in the mid-infrared (mid-IR) between 1500 and 600/cm (approx. 7 to 17 microns) have been used to infer the vertical variations of Titan's aerosol from the surface to an altitude of 300 km in the far-IR and between 150 and 350 km in the mid-IR. Titan's aerosol has several observed emission features which cannot be reproduced using currently available optical constants from laboratory-generated Titan aerosol analogs, including a broad far-IR feature centered approximately at 140/cm (71 microns).

  1. An Observational Study of the Relationship between Cloud, Aerosol and Meteorology in Broken Low-Level Cloud Conditions

    NASA Technical Reports Server (NTRS)

    Loeb, Norman G.; Schuster, Gregory L.

    2008-01-01

    Global satellite analyses showing strong correlations between aerosol optical depth and 3 cloud cover have stirred much debate recently. While it is tempting to interpret the results as evidence of aerosol enhancement of cloud cover, other factors such as the influence of meteorology on both the aerosol and cloud distributions can also play a role, as both aerosols and clouds depend upon local meteorology. This study uses satellite observations to examine aerosol-cloud relationships for broken low-level cloud regions off the coast of Africa. The analysis approach minimizes the influence of large-scale meteorology by restricting the spatial and temporal domains in which the aerosol and cloud properties are compared. While distributions of several meteorological variables within 5deg 5deg latitude-longitude regions are nearly identical under low and high aerosol optical depth, the corresponding distributions of single-layer low cloud properties and top-of-atmosphere radiative fluxes differ markedly, consistent with earlier studies showing increased cloud cover with aerosol optical depth. Furthermore, fine-mode fraction and Angstrom Exponent are also larger in conditions of higher aerosol optical depth, even though no evidence of systematic latitudinal or longitudinal gradients between the low and high aerosol optical depth populations are observed. When the analysis is repeated for all 5deg 5deg latitude-longitude regions over the global oceans (after removing cases in which significant meteorological differences are found between the low and high aerosol populations), results are qualitatively similar to those off the coast of Africa.

  2. In situ observations of aerosol physical and optical properties in northern India

    NASA Astrophysics Data System (ADS)

    Lihavainen, H.; Hyvarinen, A.; Hooda, R. K.; Raatikainen, T. E.; Sharma, V.; Komppula, M.

    2012-12-01

    The southern Asia, including India, is exposed to substantial quantities of particulate air pollution originating mainly from fossil fuel combustion and biomass burning. Besides serious adverse health effects, these aerosols cause a large reduction of solar radiation at the surface accompanied by a substantial atmospheric heating, which is expected to have significant influences on the air temperature, crop yields, livestock and water resources over the southern Asia. The various influences by aerosols in this region depend crucially on the development of aerosol emissions from household, industrial, transportation and biomass burning sectors. The main purpose of this study is to investigate several measured aerosol optical and physical properties. We take advantage of observations from two measurement stations which have been established by the Finnish Meteorological Institute and The Energy and Resources Institute. Another station is on the foothills of Himalayas, in Mukteshwar, about 350 km east of New Delhi at elevation about 2 km ASL. This site is considered as a rural background site. Measurements of aerosol size distribution (7-500 nm), PM10, PM2.5, aerosol scattering and absorption coefficients and weather parameters have been conducted since 2006. Another station is located at the outskirts of New Delhi, in Gual Pahari, about 35 km south of city centre. It is considered as an urban background site. Measurements of aerosol size distribution (7 nm- 10 μm), PM10, PM2.5, aerosol scattering and absorption coefficients, aerosol optical depth, aerosol vertical distribution (LIDAR), aerosol filter sampling for chemical characterization and weather parameters were conducted between 2008 and 2010. On the overall average PM10 and PM2.5 values were about 3-4 times higher in Gual Pahari than in Mukteshwar as expected, 216 and 126 μg m^-3, respectively. However, difference depended much on the season, so that during winter time PM10 and PM2.5 concentrations were about

  3. Aerosol cloud interactions in southeast Pacific stratocumulus: satellite observations, in situ data and regional modeling

    NASA Astrophysics Data System (ADS)

    George, Rhea

    The influence of anthropogenic aerosols on cloud radiative properties in the persistent southeast Pacific stratocumulus deck is investigated using MODIS satellite observations, in situ data from the VAMOS Ocean-Cloud-Atmosphere-Land Study Regional Experiment (VOCALS-REx), and WRF-Chem, a regional model with interactive chemistry and aerosols. An albedo proxy is derived based on the fractional coverage of low cloud (a macrophysical field) and the cloud albedo, with the latter broken down into contributions from microphysics (cloud droplet concentration, Nd and macrophysics (liquid water path). Albedo variability is dominated by low cloud fraction variability, except within 10-15° of the South American coast, where cloud albedo variability contributes significantly. Covariance between cloud fraction and cloud albedo also contributes significantly to the variance in albedo, which highlights how complex and inseparable the factors controlling albedo are. N d variability contributes only weakly, which emphasizes that attributing albedo variability to the indirect effects of aerosols against the backdrop of natural meteorological variability is extremely challenging. Specific cases of aerosol changes can have strong impacts on albedo. We identify a pathway for periodic anthropogenic aerosol transport to the unpolluted marine stratocumulus >1000 km offshore, which strongly enhances Nd and albedo in zonally-elongated 'hook'-shaped arc. Hook development occurs with Nd increasing to polluted levels over the remote ocean primarily due to entrainment of a large number of small aerosols from the free troposphere that contribute a relatively small amount of aerosol mass to the marine boundary layer. Strong, deep offshore flow needed to transport continental aerosols to the remote ocean is favored by a trough approaching the South American coast and a southeastward shift of the climatological subtropical high pressure system. DMS significantly influences the aerosol number and

  4. Observations of relative humidity effects on aerosol light scattering in the Yangtze River Delta of China

    NASA Astrophysics Data System (ADS)

    Zhang, L.; Sun, J. Y.; Shen, X. J.; Zhang, Y. M.; Che, H. C.; Ma, Q. L.; Zhang, Y. W.; Zhang, X. Y.; Ogren, J. A.

    2015-01-01

    Scattering of solar radiation by aerosol particles is highly dependent on relative humidity (RH) as hygroscopic particles take up water with increasing RH. To achieve a better understanding of the effect of aerosol hygroscopic growth on light scattering properties and radiative forcing, a field campaign was carried out in the Yangtze River Delta of China in March 2013. During the observation period, the mean and standard deviation of enhancement factors at RH=85% for the scattering coefficient (f(85%)), backscattering coefficient (fb(85%)) and hemispheric backscatter fraction (fβ(85%)) were 1.58 ± 0.12, 1.25 ± 0.07 and 0.79 ± 0.04, respectively, i.e. aerosol scattering coefficient and backscattering coefficient increased by 58 and 25% as the RH increased from 40 to 85%. Meanwhile, the aerosol hemispheric backscatter fraction decreased by 21%. The relative amount of organic matter (OM) and inorganics in PM1 was found to be a main factor determining the magnitude of f(RH), the highest values of f(RH) corresponded to the aerosols with a small fraction of organic matter (OM), and vice versa. The relative amount of NO3- in fine particles was strongly correlated to f(85%), which suggests NO3- played a vital role in aerosol hygroscopic growth during this study. The mass percentage of nitrate also had a close relation to the curvature of humidograms, namely, the higher the nitrate concentration is, the straighter the humidogram will be. Air masses that arrived at LinAn in March can be classified into northerly-polluted, locally-polluted and dust-influenced types, the scattering enhancement factors at 85% RH were 1.52 ± 0.10, 1.64 ± 0.09 and 1.48 ± 0.05, respectively. The sensitivity of the aerosol radiative forcing to f(RH) at the measured mean ambient RH 67% for various aerosol types was also estimated. The direct radiative forcing increased by 11.8, 19.5, and 10.5%, respectively, for locally-polluted, northerly-polluted and dust-influenced aerosols due to aerosol

  5. Light-absorption properties of aerosols observed in East and South Asia

    NASA Astrophysics Data System (ADS)

    Kim, S.; Yoon, S.; Lee, H.

    2011-12-01

    We compared light-absorption properties of aerosols observed in East and South Asia from black carbon (BC) mass concentration, aerosol scattering and absorption coefficients measurements at four sites: Korea Climate Observatory-Gosan (KCO-G), Korea Climate Observatory-Anmyeon (KCO-A), Maldives Climate Observatory-Hanimaadhoo (MCO-H) and Nepal Climate Observatory-Pyramid (NCO-P). No significant seasonal variations of BC mass concentration, aerosol scattering and absorption coefficients, except for summer due to wet scavenging by rainfall, were observed in East Asia, whereas dramatic changes of light-absorbing aerosol properties were observed in South Asia between dry and wet monsoon periods. Although BC mass concentration in East Asia is generally higher than that observed in South Asia, BC mass concentration at MCO-H during winter dry monsoon is similar to that of East Asia. The observed solar absorption efficiency (absorption coefficient/extinction coefficient) at 550 nm at KCO-G and KCO-A is higher than that in MCO-H due to large portions of BC emission from fossil fuel combustion. Interestingly, solar absorption efficiency at NCO-P is 0.14, which is two times great than that in MCO-H and is about 40% higher than that in East Asia, though BC mass concentration at NCO-P is the lowest among four sites. Consistently, the highest elemental carbon to sulfate ratio is found at NCO-P.

  6. Radiative Effects of Carbonaceous and Inorganic Aerosols over California during CalNex and CARES: Observations versus Model Predictions

    NASA Astrophysics Data System (ADS)

    Vinoj, V.; Fast, J. D.; Liu, Y.

    2012-12-01

    Aerosols have been identified to be a major contributor to the uncertainty in understanding the present climate. Most of this uncertainty arises due to the lack of knowledge of their micro-physical and chemical properties as well as how to adequately represent their spatial and temporal distributions. Increased process level understanding can be achieved through carefully designed field campaigns and experiments. These measurements can be used to elucidate the aerosol properties, mixing, transport and transformation within the atmosphere and also to validate and improve models that include meteorology-aerosol-chemistry interactions. In the present study, the WRF-Chem model is used to simulate the evolution of carbonaceous and inorganic aerosols and their impact on radiation during May and June of 2010 over California when two field campaigns took place: the California Nexus Experiment (CalNex) and Carbonaceous Aerosol and Radiative Effects Study (CARES). We merged CalNex and CARES data along with data from operational networks such as, California Air Resources Board (CARB's) air quality monitoring network, the Interagency Monitoring of Protected Visual Environments (IMPROVE) network, the AErosol RObotic NETwork (AERONET), and satellites into a common dataset for the Aerosol Modeling Test bed. The resulting combined dataset is used to rigorously evaluate the model simulation of aerosol mass, size distribution, composition, and optical properties needed to understand uncertainties that could affect regional variations in aerosol radiative forcing. The model reproduced many of the diurnal, multi-day, and spatial variations of aerosols as seen in the measurements. However, regionally the performance varied with reasonably good agreement with observations around Los Angeles and Sacramento and poor agreement with observations in the vicinity of Bakersfield (although predictions aloft were much better). Some aerosol species (sulfate and nitrate) were better represented

  7. Contrasting aerosol trends over South Asia during the last decade based on MODIS observations

    NASA Astrophysics Data System (ADS)

    Kaskaoutis, D. G.; Kharol, S. K.; Sinha, P. R.; Singh, R. P.; Badarinath, K. V. S.; Mehdi, W.; Sharma, M.

    2011-08-01

    Atmospheric aerosols over south Asia constitute a major environmental and climate issue. Thus, extensive land and cruise campaigns have been conducted over the area focusing on investigating the aerosol properties and climate implications. Except from the ground-based instrumentation, several studies dealt with analyzing the aerosol properties from space, focusing mainly on the spatial distribution of the aerosol optical depth (AOD) and possible feedbacks of aerosols on the monsoon system. However, except from some works using ground-based instrumentation or satellite observations over a specific region, there is lack of studies dealing with monitoring of the aerosol trend over south Asia. The present work analyzes the variations and trends in aerosol load over south Asia using Terra-MODIS AOD550 data in the period 2000-2009. Overall, an increasing trend of 10.17 % in AOD is found over whole south Asia, which exhibits large spatio-temporal variation. More specifically, the AOD550 increasing trend is more pronounced in winter, and especially over northern India. The present study shows an evidence of a decreasing AOD550 trend over the densely-populated Indo-Gangetic Plains (IGP) during the period April-September, which has never been reported before. This decreasing trend is not statistically significant and leads to an AOD change of -0.01 per year in June, when the dust activity is at its maximum. The AOD decrease seems to be attributed to weakness of dust activity in the northwest of India, closely associated with expansion of the vegetated areas and increase in precipitation over the Thar desert. Similarly, GOCART simulations over south Asia show a pronounced decreasing trend in dust AOD in accordance with MODIS. However, much more analysis and longer dataset are required for establishing this evidence.

  8. Assimilating Remote Ammonia Observations with a Refined Aerosol Thermodynamics Adjoint"

    EPA Science Inventory

    Ammonia emissions parameters in North America can be refined in order to improve the evaluation of modeled concentrations against observations. Here, we seek to do so by developing and applying the GEOS-Chem adjoint nested over North America to conductassimilation of observations...

  9. Systematic Satellite Observations of the Impact of Aerosols from Passive Volcanic Degassing on Local Cloud Properties

    NASA Technical Reports Server (NTRS)

    Ebmeier, S. K.; Sayer, A. M.; Grainger, R. G.; Mather, T. A.; Carboni, E.

    2014-01-01

    The impact of volcanic emissions is a significant source of uncertainty in estimations of aerosol indirect radiative forcing, especially with respect to emissions from passive de-gassing and minor explosions. Understanding the impact of volcanic emissions on indirect radiative forcing is important assessing present day atmospheric properties and also to define the pre-industrial baseline to assess anthropogenic perturbations. We present observations of the time-averaged indirect aerosol effect within 200 km downwind of isolated island volcanoes in regions of low present-day aerosol burden using MODIS and AATSR data. Retrievals of aerosol and cloud properties at Kilauea (Hawaii), Yasur (Vanuatu) and Piton de la Fournaise (Reunion) are rotated about the volcanic vent according to wind direction, so that retrievals downwind of the volcano can be averaged to improve signal to noise ratio. The emissions from all three volcanoes, including those from passive degassing, strombolian activity and minor explosions lead to measurably increased aerosol optical depth downwind of the active vent. Average cloud droplet effective radius is lower downwind of the volcano in all cases, with the peak difference in effective radius ranging from 48 microns at the different volcanoes. A comparison of these observations with cloud properties at isolated islands with no significant source of aerosol suggests that these patterns are not purely orographic in origin. This approach sets out a first step for the systematic measurement of the effects of present day low altitude volcanic emissions on cloud properties, and our observations of unpolluted, isolated marine settings may capture processes similar to those in the preindustrial marine atmosphere.

  10. Systematic satellite observations of the impact of aerosols from passive volcanic degassing on local cloud properties

    NASA Astrophysics Data System (ADS)

    Ebmeier, S. K.; Sayer, A. M.; Grainger, R. G.; Mather, T. A.; Carboni, E.

    2014-01-01

    The impact of volcanic emissions is a significant source of uncertainty in estimations of aerosol indirect radiative forcing, especially with respect to emissions from passive degassing and minor explosions. Understanding the impact of volcanic emissions on indirect radiative forcing is important for assessing present day atmospheric properties and also to define the pre-industrial baseline to assess anthropogenic perturbations. We present observations of the time-averaged indirect aerosol effect within 200 km downwind of isolated island volcanoes in regions of low present-day aerosol burden using MODIS and AATSR data. Retrievals of aerosol and cloud properties at Kīlauea (Hawai'i), Yasur (Vanuatu) and Piton de la Fournaise (Réunion) are rotated about the volcanic vent according to wind direction, so that retrievals downwind of the volcano can be averaged to improve signal to noise ratio. The emissions from all three volcanoes, including those from passive degassing, strombolian activity and minor explosions lead to measurably increased aerosol optical depth downwind of the active vent. Average cloud droplet effective radius is lower downwind of the volcano in all cases, with the peak difference in effective radius of 4-8 μm at the different volcanoes. A comparison of these observations with cloud properties at isolated islands with no significant source of aerosol suggests that these patterns are not purely orographic in origin. This approach sets out a first step for the systematic measurement of the effects of present day low altitude volcanic emissions on cloud properties. Our observations of unpolluted, isolated marine settings may also capture processes similar to those in the pre-industrial marine atmosphere.

  11. Observations of Aerosol Optical Properties over 15 AERONET Sites in Southeast Asia

    NASA Astrophysics Data System (ADS)

    Chan, J. D.; Lagrosas, N.; Uy, S. N.; Holben, B. N.; Dorado, S.; Tobias, V., Jr.; Anh, N. X.; Po-Hsiung, L.; Janjai, S.; Salinas Cortijo, S. V.; Liew, S. C.; Lim, H. S.; Lestari, P.

    2014-12-01

    Mean column-integrated optical properties from ground sun photometers of the Aerosol Robotic Network (AERONET) are studied to provide an overview of the characteristics of aerosols over the region as part of the 7 Southeast Asian Studies (7-SEAS) mission. The 15 AERONET sites with the most available level 2 data products are selected from Thailand (Chiang Mai, Mukdahan, Songkhla and Silpakorn University), Malaysia (University Sains Malaysia), Laos (Vientiane), Vietnam (Bac Giang, Bac Lieu and Nha Trang), Taiwan (National Cheng Kung University and Central Weather Bureau Taipei), Singapore, Indonesia (Bandung) and the Philippines (Manila Observatory and Notre Dame of Marbel University). For all 15 sites, high angstrom exponent values (α>1) have been observed. Chiang Mai and USM have the highest mean Angstrom exponent indicating the dominance of fine particles that can be ascribed to biomass burning and urbanization. Sites with the lowest Angstrom exponent values include Bac Lieu (α=1.047) and Manila Observatory (α=1.021). From the average lognormal size distribution curves, Songkhla and NDMU show the smallest annual variation in the fine mode region, indicating the observed fine aerosols are local to the sites. The rest of the sites show high variation which could be due to large scale forcings (e.g., monsoons and biomass burnings) that affect aerosol properties in these sites. Both high and low single scattering albedo at 440 nm (ω0440) values are found in sites located in major urban areas. Silpakorn University, Manila Observatory and Vientiane have all mean ω0440 < 0.90. Singapore and CWB Taipei have ω0440 > 0.94. The discrepancy in ω0 suggests different types of major emission sources present in urban areas. The absorptivity of urban aerosols can vary depending on the strength of traffic emissions, types of fuel combusted and automobile engines used, and the effect of biomass burning aerosols during the dry season. High aerosol optical depth values (τa550

  12. Stratospheric aerosol change in the early stage of volcanic disturbance by the Pinatubo eruption observed over Tsukuba, Japan

    SciTech Connect

    Hayashida, Sachiko; Sasano, Yasuhiro

    1993-04-09

    An increase in the amount of stratospheric aerosol due to the Pinatubo eruption (June 12-15, 1991, 15.14[degree]N, 120.35[degree]E) was observed from the end of June by a lidar in NIES, Tsukuba (36[degree]N, 140[degree]E). The first arrival of volcanic aerosol layers was observed just above the tropopause on June 28, 1991, only two weeks after the eruption. Aerosol layers higher than 20 km appeared sporadically in July and August, reflecting the inhomogeneity of aerosol distribution. After the change in the wind system from summer easterlies to winter westerlies, the main body of the volcanic aerosol layer made its appearance over Tsukuba. The integrated backscattering coefficient (IBC) increased in winter as a result of transportation of aerosols from the tropical region. The IBC, which can be converted to optical thickness, exceeded the level of the value observed after the El Chichon eruption. 15 refs., 4 figs.

  13. Observational challenges in Lyα intensity mapping

    NASA Astrophysics Data System (ADS)

    Comaschi, P.; Yue, B.; Ferrara, A.

    2016-09-01

    Intensity mapping (IM) is sensitive to the cumulative line emission of galaxies. As such it represents a promising technique for statistical studies of galaxies fainter than the limiting magnitude of traditional galaxy surveys. The strong hydrogen Lyα line is the primary target for such an experiment, as its intensity is linked to star formation activity and the physical state of the interstellar (ISM) and intergalactic (IGM) medium. However, to extract the meaningful information one has to solve the confusion problems caused by interloping lines from foreground galaxies. We discuss here the challenges for a Lyα IM experiment targeting z > 4 sources. We find that the Lyα power spectrum can be in principle easily (marginally) obtained with a 40 cm space telescope in a few days of observing time up to z ≲ 8 (z ˜ 10) assuming that the interloping lines (e.g. Hα, [O II], [O III] lines) can be efficiently removed. We show that interlopers can be removed by using an ancillary photometric galaxy survey with limiting AB mag ˜26 in the NIR bands (Y, J, H, or K). This would enable detection of the Lyα signal from 5 < z < 9 faint sources. However, if a [C II] IM experiment is feasible, by cross-correlating the Lyα with the [C II] signal the required depth of the galaxy survey can be decreased to AB mag ˜24. This would bring the detection at reach of future facilities working in close synergy.

  14. Exploiting Representation of the Aerosol-Radiation interactions in Climate Systems: Observation-based Analyses and Global Climate Modeling

    NASA Astrophysics Data System (ADS)

    Chen, Y. C.; Li, J.; Lee, W. L.; Diner, D. J.; Garay, M. J.; Kalashnikova, O. V.

    2015-12-01

    Aerosols affect the Earth's climate by perturbing the radiation budget through scattering and absorption of solar radiation and emitting thermal infrared radiation (defined and referred to as aerosol direct effect). At first order, it is essential for a model to realistically represent the distributions of clouds, convection, aerosol profiles and their associated radiative properties (cloud fraction and effective radius), which are critical for simulating Earth's surface energy and water budgets. The representation of aerosols and their radiative properties remains problematic both in retrieval and modeling. Up to now, the representation of aerosol optical depth (AOD) in GCMs is still far from agreement with the observation. We evaluate the aerosol simulations from the 20th century CMIP5 simulations, and investigate the biases in aerosol loadings against observations. AOD and retrieved aerosol types (e.g., sea salt, organic matter, sulfate) from MISR, MODIS, and CALIPSO satellite observations are utilized to compare with model simulated aerosols. The impacts of the biases of modeled AOD and cloud fraction on aerosol direct effects in GCMs will be presented.

  15. 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.

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

    NASA Technical Reports Server (NTRS)

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

    2002-01-01

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

  17. 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.

  18. Carbonaceous aerosols observed at Ieodo Ocean Research Station and implication for the role of secondary aerosols in fog formation

    NASA Astrophysics Data System (ADS)

    Han, J.; Shin, B.; Hwang, G.; Kim, J.; Lee, M.; Shim, J.

    2014-12-01

    Carbonaceous components and soluble ions of PM2.5 were measured at Ieodo Ocean Research Station (IORS) from December 2004 to June 2008. IORS is a 40-m research tower and located in the East China Sea (32.07°N, 125.10°E). As IORS is distanced equally from South Korea, China, and Japan, it is an ideal place to monitor Asian outflows with the least influence of local emissions. The mean concentration of PM2.5 mass was 21.8 ± 14.9 μg/m3 with the maximum of 35.3 μg/m3 (March) and the minimum of 11.2 μg/m3 (September). The monthly variation of PM2.5 mass was similar to that of O3 due to meteorological conditions, which determines the degree of influence from nearby lands. Chinese outflows were mostly responsible for the enhancement of mass and major constituents of PM2.5 such as sulfate, OC, and EC. Their concentrations were the lowest in summer when aged marine air masses were dominant. It is noteworthy that sulfate was also enhanced when air mass passed through Japan, even though its concentration was not as high as that of Chinese outflows. In June, OC concentration was distinctively high with high OC/EC ratio of ~9.5. At IORS, June is characterized by the most frequent occurrence of fog and the lowest visibility with the highest relative humidity. In China, the clearing fire of agricultural residues is the major source of fine aerosols in June, leading to severe haze (e.g., Cheng et al., 2014). In addition, the aerosol optical depth was also observed to be the maximum over northeast Asia in June (Kim et al., 2007). Consequently, our results suggest that organic aerosol played a critical role in fog formation in the study region. References Cheng, Z., et al. (2014) Impact of biomass burning on haze pollution in the Yangtze River delta, China: a case study in summer 2011, Atmos. Chem. Phys., 14, 4573-4585, doi:10.5194/acp-14-4573-2014. Kim, S.-W., et al. (2007) Seasonal and monthly variations of columnar aerosol optical properties over east Asia determined from

  19. Evaluation of aerosol simulation in a global model using multiple-platform observations

    NASA Astrophysics Data System (ADS)

    Ma, X.

    2015-12-01

    Large diversity in the magnitude of aerosol optical depth (AOD) and their spatial distributions is one of key factors contributing to the large uncertainty of the model predicted aerosol radiative forcing (global mean ranging from -0.02 to -0.58W m-2) and its climatic effect. Therefore, evaluation of model performances with respect to AOD is a critical step to improve the model simulations and, thus, reduce the diversities. In this study, multi-year AOD data (2004-2012) from ground-based Aerosol Robotic Network (AERONET) measurements and Moderate Resolution Imaging Spectroradiometer (MODIS), Multiangle Imaging SpectroRadiometer (MISR) and Sea-viewing Wide Field-of-view Sensor (SeaWiFS) satellite retrievals are used to evaluate the performance of a global model, GEOS-Chem-APM, one of global models involved in AeroCom phase II aerosol module inter-comparison project. Comparisons of the modeled AOD with satellite data on spatial distribution, seasonal and inter-annual variations are quantitatively analyzed. In addition, several regions representative of various aerosol dominant species are chose for the detailed evaluations of AOD between the simulation and AERONET observations. The capability and weakness of the model to capture seasonal variation and chemical species is also discussed for further improvement in the future.

  20. Evaluating rainfall kinetic energy - intensity relationships with observed disdrometric data

    NASA Astrophysics Data System (ADS)

    Angulo-Martinez, Marta; Begueria, Santiago; Latorre, Borja

    2016-04-01

    Rainfall kinetic energy is required for determining erosivity, the ability of rainfall to detach soil particles and initiate erosion. Its determination relay on the use of disdrometers, i.e. devices capable of measuring the drop size distribution and velocity of falling raindrops. In the absence of such devices, rainfall kinetic energy is usually estimated with empirical expressions relating rainfall energy and intensity. We evaluated the performance of 14 rainfall energy equations in estimating one-minute rainfall energy and event total energy, in comparison with observed data from 821 rainfall episodes (more than 100 thousand one-minute observations) by means of an optical disdrometer. In addition, two sources of bias when using such relationships were evaluated: i) the influence of using theoretical terminal raindrop fall velocities instead of measured values; and ii) the influence of time aggregation (rainfall intensity data every 5-, 10-, 15-, 30-, and 60-minutes). Empirical relationships did a relatively good job when complete events were considered (R2 > 0.82), but offered poorer results for within-event (one-minute resolution) variation. Also, systematic biases where large for many equations. When raindrop size distribution was known, estimating the terminal fall velocities by empirical laws produced good results even at fine time resolution. The influence of time aggregation was very high in the estimated kinetic energy, although linear scaling may allow empirical correction. This results stress the importance of considering all these effects when rainfall energy needs to be estimated from more standard precipitation records. , and recommends the use of disdrometer data to locally determine rainfall kinetic energy.

  1. Retrieving the Height of Smoke and Dust Aerosols by Synergistic Use of VIIRS, OMPS, and CALIOP Observations

    NASA Technical Reports Server (NTRS)

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

    2015-01-01

    Aerosol Single scattering albedo and Height Estimation (ASHE) algorithm was first introduced in Jeong and Hsu (2008) to provide aerosol layer height as well as single scattering albedo (SSA) for biomass burning smoke aerosols. One of the advantages of this algorithm was that the aerosol layer height can be retrieved over broad areas, which had not been available from lidar observations only. The algorithm utilized aerosol properties from three different satellite sensors, i.e., aerosol optical depth (AOD) and Ångström exponent (AE) from Moderate Resolution Imaging Spectroradiometer (MODIS), UV aerosol index (UVAI) from Ozone Monitoring Instrument (OMI), and aerosol layer height from Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP). Here, we extend the application of the algorithm to Visible Infrared Imaging Radiometer Suite (VIIRS) and Ozone Mapping and Profiler Suite (OMPS) data. We also now include dust layers as well as smoke. Other updates include improvements in retrieving the AOD of nonspherical dust from VIIRS, better determination of the aerosol layer height from CALIOP, and more realistic input aerosol profiles in the forward model for better accuracy.

  2. Joint retrieval of surface reflectance and aerosol optical depth from MSG/SEVIRI observations with an optimal estimation approach: 2. Implementation and evaluation

    NASA Astrophysics Data System (ADS)

    Wagner, S. C.; Govaerts, Y. M.; Lattanzio, A.

    2010-01-01

    An original method, based on optimal estimation, was presented in a part one of this paper for the joint retrieval of the mean daily total column aerosol optical depth and the surface Bidirectional Reflectance Factor (BRF) from the daily accumulated Meteosat Second Generation-Spinning Enhanced Visible and Infrared Imager (MSG/SEVIRI) observations in the solar channels. The objective of this paper is to evaluate the benefits of the proposed approach and to document the limits of the algorithm assumptions in the context of its implementation in an operational ground segment. A twofold approach is followed. In a first step, by looking at the posterior correlation error matrix the capability of the so-called Land Daily Aerosol (LDA) algorithm to decouple the surface-atmosphere signal is analyzed. In particular, the impact of the prior information is investigated in detail. In a second step, the results of the algorithm are compared with independent data sets of aerosol optical depth and surface reflectance. In this phase, the accuracy of the algorithm is evaluated against ground observations from the AERONET network. LDA is shown to be in good agreement with these data, especially when the prior update mechanism is activated. Comparisons with the MODIS surface product showed that the bihemispherical reflectance derived from the LDA products is consistent with the equivalent MODIS white-sky albedo. Aerosol spatial distributions are comparable in terms of geographical location and intensity, in particular for aerosol episodes with a limited daily variation.

  3. Do aerosols impact ground observation of total cloud cover over the North China Plain?

    NASA Astrophysics Data System (ADS)

    Sun, Li; Xia, Xiangao; Wang, Pucai; Fei, Ye

    2015-04-01

    Ground observation of the total cloud cover (TCC) showed a significant downward trend during the past half century over the North China Plain (NCP). The objective of this paper is to examine whether aerosols have impacted the surface observations of TCC by human observers. TCC observations by the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard the Aqua (TCCgrd) were firstly compared with ground observations (TCCsat) at 201 synoptic stations over the NCP. Results showed that both data sets were in good agreement. The correlation coefficient between TCCgrd and TCCsatranged from 0.80 in winter to 0.90 in summer. The relationship between TCCsat - TCCgrdand visibility was then analyzed, which showed no significant correlation. Finally, long-term trends of TCCgrd and visibility were not correlated. These results indicated that aerosols likely did not impact the long-term trend of TCCgrdover the NCP.

  4. Do aerosols impact ground observation of total cloud cover over the North China Plain?

    NASA Astrophysics Data System (ADS)

    Sun, L.; Xia, X.; Wang, P.; Fei, Y.

    2014-06-01

    Ground observation of the total cloud cover (TCC) showed a significant downward trend during the past half century over the North China Plain (NCP). The objective of this paper is to examine whether aerosols have impacted the surface observations of TCC by human observers. TCC observations by the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard the Aqua (TCCsat) were firstly compared with ground observations (TCCgrd) at 201 synoptic stations over the NCP. Results showed that both data sets were in good agreement. The correlation coefficient between TCCgrd and TCCsat ranged from 0.80 in winter to 0.90 in summer. The relationship between TCCsat-TCCgrd and visibility was then analyzed, which showed no significant correlation. Finally, long-term trends of TCCgrd and visibility were not correlated. These results indicated that aerosols likely did not impact the long-term trend of TCCgrd over the NCP.

  5. Assessment of satellite-based aerosol optical depth using continuous lidar observation

    NASA Astrophysics Data System (ADS)

    Lin, C. Q.; Li, C. C.; Lau, A. K. H.; Yuan, Z. B.; Lu, X. C.; Tse, K. T.; Fung, J. C. H.; Li, Y.; Yao, T.; Su, L.; Li, Z. Y.; Zhang, Y. Q.

    2016-09-01

    Due to a reliance on solar radiation, the aerosol optical depth (AOD) is observed only during the day by passive satellite-based instruments such as the MODerate resolution Imaging Spectroradiometer (MODIS). Research on urban air quality, atmospheric turbidity, and evolution of aerosols in the atmospheric boundary layer, however, requires 24-h measurement of aerosols. A lidar system is capable of detecting the vertical distribution of the aerosol extinction coefficient and calculating the AOD throughout the day, but routinely lidar observation is still quite limited and the results from MODIS and lidar sometimes are contradictory in China. In this study, long-term lidar observations from 2005 to 2009 over Hong Kong were analyzed with a focus on identification of the reasons for different seasonal variation in the AOD data obtained from MODIS and lidar. The lidar-retrieved AOD shows the lowest average level, but has the most significant diurnal variation during the summer. When considering only a 5-h period between 10:00 a.m. and 3:00 p.m. local time to match satellite passages, the average of the lidar-retrieved AOD doubles during the summer and exceeds that during the winter. This finding is consistent with the MODIS observation of a higher AOD during the summer and a lower AOD during the winter. The increase in the aerosol extinction coefficient in the upper level of the mixing layer makes the greatest contribution to the increase in the AOD at midday during the summer. These assessments suggest that large over-estimation may occur when long-term averages of AOD are estimated from passive satellite observations.

  6. GRASP Algorithm: retrieval of the aerosol properties over land surface from satellite observations (solicited)

    NASA Astrophysics Data System (ADS)

    Dubovik, Oleg; Litvinov, Pavel; Lapyonok, Tatyana; Ducos, Fabrice; Aspetsberger, Michael; Planer, Wolfgang; Federspiel, Christian; Fuertes, David

    The GRASP (Generalized Retrieval of Aerosol and Surface Properties) algorithm has been developed for enhanced characterization of the properties of both aerosol and land surface from diverse remote sensing observations. The concept of the algorithm is described in details by Dubovik et al. (2011). The algorithm is based on highly advanced statistically optimized fitting implemented as Multi-Term Least Square minimization (Dubovik, 2004) and deduces nearly 50 unknowns for each observed site. The algorithm derives a set of aerosol parameters similar to that derived by AERONET including detailed particle size distribution, the spectral dependence on the complex index of refraction and the fraction of non-spherical particles. The algorithm uses detailed aerosol and surface models and fully accounts for all multiple interactions of scattered solar light with aerosol, gases and the underlying surface. All calculations are done on-line without using traditional look-up tables. In addition, the algorithm can use the new multi-pixel concept - a simultaneous fitting of a large group of pixels with additional constraints limiting the time variability of surface properties and spatial variability of aerosol properties. This principle provides a possibility to improve retrieval for multiple observations even if the observations are not exactly co-incident or co-located. Significant efforts have been spent for optimization and speedup of the GRASP computer routine and retrievals from satellite observations. For example, the routine has been adapted for running at GPGPUs accelerators. Originally GRASP has been developed for POLDER/PARASOL multi-viewing imager and later adapted to a number of other satellite sensors such as MERIS at polar-orbiting platform and COCI/GOMS geostationary observations. The results of numerical tests and results of applications to real data will be presented. REFERENCES: Dubovik, et al.,“Statistically optimized inversion algorithm for enhanced

  7. Airborne Observations of Regional Variations in Fluorescent Aerosol Across the U.S.

    NASA Astrophysics Data System (ADS)

    Perring, A. E.; Schwarz, J. P.; Baumgardner, D.; Hernandez, M.; Spracklen, D. V.; Heald, C. L.; Gao, R. S.; Kok, G. L.; McMeeking, G.; McQuaid, J. B.; Fahey, D. W.

    2014-12-01

    Airborne observations of fluorescent aerosol were made aboard an airship during CloudLab, a series of flights that took place in September and October of 2013 and covered a wide band of longitude across the continental US between Florida and California between 28 and 37N latitude. Sampling occurred from near the surface to 1000 m above the ground. A Wide-band Integrated Bioaerosol Sensor (WIBS-4) measured concentrations of supermicron fluorescent particles with average regional concentrations ranging from 1.4±0.7 to 6.8±1.4 x 104 particles m-3 and representing up to 24% of total supermicron particle number. We observed distinct variations in size distributions and fluorescent characteristics in different regions, and attribute these to geographically diverse bioaerosol populations. Fluorescent aerosol signatures detected in the east is largely consistent with those of mold spores observed in a laboratory setting. A shift to larger sizes associated with different fluorescent patterns is observed in the west. Loadings in the desert west were nearly as high as those near the Gulf of Mexico, indicating that bioaerosol is a substantial component of supermicron aerosol both of these humid and arid environments. The observations are compared to simulated fungal and bacterial loadings. Good agreement in both particle size and concentrations is observed in the east. In the west the model underestimates observed concentrations by a factor of 2 to 3 and the prescribed particle sizes are smaller than the observed bioaerosol.

  8. Primary carbonaceous aerosols and climate modeling: Classifications, global emission inventories, and observations

    NASA Astrophysics Data System (ADS)

    Sun, H.; Bond, T.

    2004-12-01

    organics in aerosols, we propose a Climate-Relevant Optical & Structural Subgroups of OC (CROSS-OC) which is a classification for organic aerosols based on structural and optical properties. We provide broad classes aiming at global models instead of very detailed classifications, which are not amenable for use in global-scale models due to the calculation cost. Organic matter (OM) which includes the hydrogen and oxygen bound to this carbon is divided into classes with varied absorption and scattering capabilities. Because our inventory tabulates emissions from specific sources, we make use of data available from source characterization. We present a global emission inventory of primary carbonaceous aerosols that has been designed for global climate modeling purpose. The inventory is based on our CROSS-OC classification and considers emissions from fossil fuels, biofuels, and open biomass burning. Fuel type, combustion type, and emission controls, and their prevalence on a regional basis are combined to determine emission factors for all types of carbonaceous aerosols. We also categorize surface concentration observations for BC and OC by region, size (super vs. sub micron), measurement type, time (including season) and date. We parallel the data format suggested by the Global Atmosphere Watch aerosol database. Work underway includes providing information on the CROSS-OC divisions in ambient aerosol when measurements contain sufficient detail.

  9. Lidar Observation of Aerosol and Temperature Stratification over Urban Area During the Formation of a Stable Atmospheric PBL

    NASA Technical Reports Server (NTRS)

    Kolev, I.; Parvanov, O.; Kaprielov, B.; Mitev, V.; Simeonov, V.; Grigorov, I.

    1992-01-01

    In recent years, the processes in the atmospheric planetary boundary layer (PBL) over urban areas were intensely investigated, due to ecological problems related to the air, soil, and water pollution. New pollution sources in new residential districts, when in contradiction to the microclimate and topography requirements of that region, create a number of considerable hazards and problems. The present study is a continuation of our preceding investigations and aims at revealing the aerosol structure and stratification during the transition after sunset as measured by two lidars. Such observation of the nocturnal, stable PBL formation over an urban area in Bulgaria has not been reported before. The lidars' high time and spatial resolutions allow the changes of the internal structure of the PBL's part located above the surface layer to be observed.

  10. Direct observation of aerosol particles in aged agricultural biomass burning plumes impacting urban atmospheres

    NASA Astrophysics Data System (ADS)

    Li, W. Y.; Shao, L. Y.

    2010-04-01

    Emissions from agricultural biomass burning (ABB) in northern China have a significant impact on the regional and the global climate. According to the Giovanni's Aerosol optical depth (AOD) map, the monthly average AOD at 550 nm in northern China in 2007 shows a maximum value of 0.7 in June, suggesting that episodes of severe aerosol pollution occurred in this region. Aerosol particles were collected in urban Beijing during regional brown hazes from 12 to 30 June, 2007. Transmission electron microscopy with energy-dispersive X-ray spectrometry characterized the morphology, composition, and mixing state of aerosol particles. Potassium salts (K2SO4 and KNO3), ammonium sulfate, soot, and organic particles predominated in fine particles (diameter <1 μm) collected from 12 to 20 June, 2007. In contrast, from 21 to 30 June, 2007, ammonium sulfate, soot, and organic particles were dominant. Potassium-dominant particles as a tracer of biomass burning, together with wildfire maps, show that intensive regional ABB in northern China from 10 to 20 June, 2007 contributed significantly to the regional haze. After long-range transport, ABB particles exhibited marked changes in their morphology, elemental composition, and mixing state. Heterogeneous reactions completely converted KCl particles from ABB into K2SO4 and KNO3. Soot particles were generally mixed with potassium salts, ammonium salts, and organic particles. In addition, the abundant aged organic particles and soluble salts emitted by ABB become more hygroscopic and increase their size during long-range transport, becoming in effect additional cloud condensation nuclei. The high AOD (average value at 2.2) during 12 to 20 June, 2007, in Beijing is partly explained by the hygroscopic growth of aged fine aerosol particles and by the strong absorption of internally mixed soot particles, both coming from regional ABB emissions.

  11. Combined observational and modeling based study of the relationship between aerosols and super-cooled cloud fraction

    NASA Astrophysics Data System (ADS)

    Storelvmo, T.; Lohmann, U.; Choi, Y.

    2011-12-01

    Recent observational and modeling studies indicate that aerosols may have a strong effect on Earth's energy budget via their influence on mixed-phase clouds. Global climate studies have predicted aerosol interaction with mixed-phase clouds to warm the current climate, but estimates are uncertain because mixed-phase cloud processes in GCMs are highly parameterized and have to date been poorly constrained by satellite data. Here, we present global and regional distributions of the frequency of supercooled cloud water and its link to aerosols from two global climate models (GCMs), compared to a new satellite data set. Both GCMs link ice formation at temperatures between -40 and 0 degrees C to the simulated concentrations of aerosols with ice nucleating ability (IN), assigning different freezing efficiencies to the different insoluble aerosol species (mineral dust, bio-aerosols and soot). Consequently, both models generally simulate an anti-correlation between aerosol abundance and supercooled liquid water in clouds, a finding that was recently qualitatively confirmed by satellite observations. By studying the relationship between aerosols and the supercooled cloud fraction (SCF) from the GCMs and from the NASA spaceborne lidar instrument CALIOP (cloud-aerosol lidar with orthogonal polarization), we get strong indications of how aerosols may influence mixed-phase clouds. Furthermore, based on the guidance from the satellite data, we perform global sensitivity simulations of the radiative effects associated with aerosol influence on mixed-phase clouds. We argue that with the new validation of SCF and its link to aerosols, GCM estimates of aerosol effects on climate via their influence on mixed-phase clouds may become more reliable.

  12. Airborne observations of regional variation in fluorescent aerosol across the United States

    NASA Astrophysics Data System (ADS)

    Perring, A. E.; Schwarz, J. P.; Baumgardner, D.; Hernandez, M. T.; Spracklen, D. V.; Heald, C. L.; Gao, R. S.; Kok, G.; McMeeking, G. R.; McQuaid, J. B.; Fahey, D. W.

    2015-02-01

    Airborne observations of fluorescent aerosol were made aboard an airship during CloudLab, a series of flights that took place in September and October of 2013 and covered a wideband of longitude across the continental U.S. between Florida and California and between 28 and 37 N latitudes. Sampling occurred from near the surface to 1000 m above the ground. A Wideband Integrated Bioaerosol Sensor (WIBS-4) measured average concentrations of supermicron fluorescent particles aloft (1 µm to 10 µm), revealing number concentrations ranging from 2.1 ± 0.8 to 8.7 ± 2.2 × 104 particles m-3 and representing up to 24% of total supermicron particle number. We observed distinct variations in size distributions and fluorescent characteristics in different regions, and attribute these to geographically diverse bioaerosol. Fluorescent aerosol detected in the east is largely consistent with mold spores observed in a laboratory setting, while a shift to larger sizes associated with different fluorescent patterns is observed in the west. Fluorescent bioaerosol loadings in the desert west were as high as those near the Gulf of Mexico, suggesting that bioaerosol is a substantial component of supermicron aerosol both in humid and arid environments. The observations are compared to model fungal and bacterial loading predictions, and good agreement in both particle size and concentrations is observed in the east. In the west, the model underestimated observed concentrations by a factor between 2 and 4 and the prescribed particle sizes are smaller than the observed fluorescent aerosol. A classification scheme for use with WIBS data is also presented.

  13. Reactive nitrogen, ozone, and nitrate aerosols observed in the Arctic stratosphere in January 1990

    SciTech Connect

    Kondo, Y.; Koike, M.; Iwasaka, Y.; Hayashi, M.; Aimedieu, P.; Newman, P.A.; Matthews, W.A.; Sheldon, W.R.

    1992-08-20

    This paper reports balloon borne measurements on two days in January 1990, from Sweden, of stratospheric densities of reactive nitrogen, nitrate aerosols, and ozone. On one days the measurements were inside the polar vortex, and on the second outside. Reactive nitrogen levels were depressed inside the vortex, which is interpreted in terms of the cold temperatures during December and early January which other measurements support. Denitrification is observed inside the vortex, relative to typical number densities observed when outside the vortex.

  14. Cloud atlas for the FIRE Cirrus Intensive Field Observation (IFO)

    NASA Technical Reports Server (NTRS)

    Arking, Albert; Childs, Jeffrey D.; Merritt, John H.; Williams, Sharen L.

    1990-01-01

    An Intensive Field Observation (IFO) of cirrus clouds was conducted over the mid-western U.S. during the period October 13 to November 2, 1986. This activity, part of the First ISCCP Regional Experiment (FIRE), included measurements made from specially deployed instruments on the ground, balloons, and aircraft as well as observations from existing operational and experimental satellites. One of the sets of satellite observations was the radiance measurements made with the 5-channel AVHRR radiometer on the NOAA 9 polar orbiting meteorological satellite. The ground resolution of the measurements at nadir is approx. 1 km. It is these measurements, made once each day at approximately 2:30 p.m. local time, that were used in determining the present cloud atlas. The area covered by the atlas is slightly larger than the area specified for the IFO, in order to be in alignment with the grid that will be used in a forthcoming atlas for the larger, ETO region. The atlas contains four pages of information for each satellite pass. The 1st page of each group shows the distribution of measured radiances in channel 1 (normalized to the incoming solar flux multiplied by the cosine of the solar zenith angle) and in channel 4 for the area as a whole and for each analysis box. The 2nd page shows the images in: channels 1 and 2, channel 3R; and channel 4. The 3rd page shows the retrieved parameters in graphical form for the region as a whole and for each analysis box, where cloud fraction appears as a contour plot with respect to optical thickness and cloudtop temperature. The 4th page provides a statistical summary of the retrieved parameters in numerical form for each analysis box.

  15. Use of Multiangle Satellite Observations To Retrieve Aerosol Properties and Ocean Color

    NASA Astrophysics Data System (ADS)

    Martonchik, J.; Diner, D.; Kahn, R.

    2004-05-01

    Retrieval of aerosol optical depth over ocean is routinely performed by many different single-view satellite instruments. Because most of the ocean surface is sufficiently black in the red and near-IR, its reflectance at these wavelengths can be conveniently ignored, which greatly simplifies the retrieval process. Once the aerosol properties are determined using these wavelengths, the scene can then be atmospherically corrected to determine the amount of water-leaving radiance in all the visible spectral bands of the instrument (i.e., the ocean color). It is this particular surface information which can be analyzed to determine aspects of the biological and chemical content of the water. However, there are many regions where this black water criterion is not met, particularly in coastal waters with continental runoff and areas with heavy phytoplankton bloom. In these situations, aerosol retrievals become much more difficult and the ocean color more uncertain. Preliminary studies indicate that simultaneous (or near-simultaneous) multiangle satellite observations (e.g., by MISR) of the ocean can help to provide more robust aerosol and ocean color retrievals. Here, the directional properties of the ocean color radiances (and not the lack of ocean color in the red and near-IR) can potentially supply the necessary surface constraint needed to perform a reasonably accurate aerosol and ocean color retrieval. As such, the applicability of this retrieval algorithm could extend over a much wider range of water conditions than is currently routinely attempted. An additional benefit of this approach is that it allows all spectral bands of the the multiangle instrument to be used by the algorithm, thus providing a more robust determination of aerosol properties. We will show some results of case studies using MISR data, performed over different water conditions (open ocean, coastal waters, blooms), and will assess the potential of using surface constraints based on the

  16. Aerosol indirect effect on warm clouds over South-East Atlantic, from co-located MODIS and CALIPSO observations

    NASA Astrophysics Data System (ADS)

    Costantino, L.; Bréon, F.-M.

    2013-01-01

    In this study, we provide a comprehensive analysis of aerosol interaction with warm boundary layer clouds over the South-East Atlantic. We use aerosol and cloud parameters derived from MODIS observations, together with co-located CALIPSO estimates of the layer altitudes, to derive statistical relationships between aerosol concentration and cloud properties. The CALIPSO products are used to differentiate between cases of mixed cloud-aerosol layers from cases where the aerosol is located well-above the cloud top. This technique allows us to obtain more reliable estimates of the aerosol indirect effect than from simple relationships based on vertically integrated measurements of aerosol and cloud properties. Indeed, it permits us to somewhat distinguish the effects of aerosol and meteorology on the clouds, although it is not possible to fully ascertain the relative contribution of each on the derived statistics. Consistently with the results from previous studies, our statistics clearly show that aerosol affects cloud microphysics, decreasing the Cloud Droplet Radius (CDR). The same data indicate a concomitant strong decrease in cloud Liquid Water Path (LWP), which is inconsistent with the hypothesis of aerosol inhibition of precipitation (Albrecht, 1989). We hypothesise that the observed reduction in LWP is the consequence of dry air entrainment at cloud top. The combined effect of CDR decrease and LWP decrease leads to rather small sensitivity of the Cloud Optical Thickness (COT) to an increase in aerosol concentration. The analysis of MODIS-CALIPSO coincidences also evidences an aerosol enhancement of low cloud cover. Surprisingly, the Cloud Fraction (CLF) response to aerosol invigoration is much stronger when (absorbing) particles are located above cloud top than in cases of physical interaction. This result suggests a relevant aerosol radiative effect on low cloud occurrence: absorbing particles above the cloud top may heat the corresponding atmosphere layer

  17. Aerosol indirect effect on warm clouds over South-East Atlantic, from co-located MODIS and CALIPSO observations

    NASA Astrophysics Data System (ADS)

    Costantino, Lorenzo; Bréon, François-Marie

    2013-04-01

    In this study, we provide a comprehensive analysis of aerosol interaction with warm boundary layer clouds over the South-East Atlantic. We use aerosol and cloud parameters derived from MODIS observations, together with co-located CALIPSO estimates of the layer altitudes, to derive statistical relationships between aerosol concentration and cloud properties. The CALIPSO products are used to differentiate between cases of mixed cloud-aerosol layers from cases where the aerosol is located well-above the cloud top. This technique allows us to obtain more reliable estimates of the aerosol indirect effect than from simple relationships based on vertically integrated measurements of aerosol and cloud properties. Indeed, it permits us to somewhat distinguish the effects of aerosol and meteorology on the clouds, although it is not possible to fully ascertain the relative contribution of each on the derived statistics. Consistently with the results from previous studies, our statistics clearly show that aerosol affects cloud microphysics, decreasing the Cloud Droplet Radius (CDR). The same data indicate a concomitant strong decrease in cloud Liquid Water Path (LWP), which is inconsistent with the hypothesis of aerosol inhibition of precipitation (Albrecht, 1989). We hypothesise that the observed reduction in LWP is the consequence of dry air entrainment at cloud top. The combined effect of CDR decrease and LWP decrease leads to rather small sensitivity of the Cloud Optical Thickness (COT) to an increase in aerosol concentration. The analysis of MODIS-CALIPSO coincidences also evidences an aerosol enhancement of low cloud cover. Surprisingly, the Cloud Fraction (CLF) response to aerosol invigoration is much stronger when (absorbing) particles are located above cloud top than in cases of physical interaction. This result suggests a relevant aerosol radiative effect on low cloud occurrence: absorbing particles above the cloud top may heat the corresponding atmosphere layer

  18. 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.

  19. Observed aerosol-induced radiative effect on plant productivity in the eastern United States

    NASA Astrophysics Data System (ADS)

    Strada, S.; Unger, N.; Yue, X.

    2015-12-01

    We apply satellite observations of aerosol optical depth (AOD) in conjunction with flux tower-derived estimates of gross primary productivity (GPP) to probe the relationship between atmospheric aerosol loading and carbon uptake rate at 10 select sites (4 deciduous broadleaf, 3 cropland, 1 evergreen needle leaf, 1 mixed forest and 1 grassland) on hourly time scales in the growing season in the eastern United States. For deciduous and mixed forests, the aerosol light scattering increases GPP with a maximum effect observed under polluted conditions (AOD >0.6), when diffuse radiation is 40-60%. During midday hours, high AOD conditions (>0.4) enhance plant productivity by ∼13% in deciduous forests. In contrast, we find that high diffuse light fraction does not increase the carbon uptake rate in croplands and grasslands; for these ecosystems, we estimate that high AOD conditions reduce GPP by ∼17% during midday hours. Our findings are consistent with previous studies that have attributed these contrasting response sensitivities to the complex and closed canopy architecture of forests versus crops and grasslands. C4 but not C3 crops may benefit from pollution-induced changes in diffuse and direct light. Further research is needed to investigate the role of local meteorology as a possible confounder in the connection between atmospheric aerosols and plant productivity.

  20. Assimilating aerosol observations with a "hybrid" variational-ensemble data assimilation system

    NASA Astrophysics Data System (ADS)

    Schwartz, Craig S.; Liu, Zhiquan; Lin, Hui-Chuan; Cetola, Jeffrey D.

    2014-04-01

    Total 550 nm aerosol optical depth, surface fine particulate matter (PM2.5), and meteorological observations were assimilated with continuously cycling three-dimensional variational (3DVAR), ensemble square root Kalman filter (EnSRF), and hybrid variational-ensemble data assimilation systems. The hybrid system's background error covariances (BECs) were a blend of those in 3DVAR and produced by the cycling EnSRF system, and the 3DVAR, EnSRF, and hybrid systems differed almost exclusively by their BECs. New analyses were produced every 6 h between 0000 UTC 1 June and 1800 UTC 14 July 2010 over a domain encompassing the contiguous United States (CONUS) and adjacent areas. Additionally, a control experiment that only assimilated meteorological observations was performed. Each 1800 UTC analysis initialized a 48 h Weather Research and Forecasting with Chemistry model forecast. These forecasts were evaluated with a focus on air quality prediction. The ensemble aerosol spread was generally insufficient, particularly over the western CONUS. However, despite the suboptimal ensemble spread, the hybrid system performed quite well and usually produced the best aerosol forecasts. Additionally, both the 3DVAR- and EnSRF-initialized forecasts typically outperformed the control. These results are encouraging and suggest the resiliency of the hybrid method. Improved aerosol ensembles should translate into even better future hybrid forecasts.

  1. On the radiative impact of aerosols on photolysis rates: comparison of simulations and observations in the Lampedusa island during the ChArMEx/ADRIMED campaign

    NASA Astrophysics Data System (ADS)

    Mailler, S.; Menut, L.; di Sarra, A. G.; Becagli, S.; Di Iorio, T.; Formenti, P.; Bessagnet, B.; Briant, Régis; Gómez-Amo, J. Luis; Mallet, M.; Rea, Géraldine; Siour, G.; Sferlazzo, D. M.; Traversi, R.; Udisti, R.; Turquety, S.

    2015-03-01

    The Mediterranean basin is characterized by large concentrations of aerosols from both natural and anthropogenic sources. These aerosols change the optical properties of the atmosphere, therefore affecting tropospheric photochemistry through the photolytic rates. Two simulations of the atmospheric composition at basin-scale have been performed with the CHIMERE chemistry-transport model for the period from 1 June to 15 July 2013 covered by the ADRIMED campaign, a campaign of intense measurements in the western Mediterranean basin. One simulation takes into account the radiative effect of the aerosols on photochemistry, the other one does not. These simulations are compared to satellite and ground-based measurements, with a particular focus on the area of Lampedusa. Values of the Aerosol Optical Depth (AOD) are obtained from the MODIS instrument on the AQUA and TERRA satellites as well as from stations in the AERONET network and from the MFRSR sun photometer deployed at Lampedusa. Additional measurements from instruments deployed at Lampedusa either permanently or exceptionnally are used for other variables: MFRSR sun photometer for AOD, diode array spectrometer for actinic fluxes, LIDAR for the aerosol backscatter, sequential sampler for speciation of aerosol and Brewer spectrophotometer for the total ozone column. It is shown that CHIMERE has a significant ability to reproduce observed peaks in the AOD, which in Lampedusa are mainly due to dust outbreaks during the ADRIMED period, and that taking into account the radiative effect of the aerosols in CHIMERE improves considerably the ability of the model to reproduce the observed day-to-day variations of J(O1D) and J(NO2). While in the case of J(O1D) other variation factors such as the stratospheric ozone column are very important in representing correctly the day-to-day variations, the day-to-day variations of J(NO2) are captured almost completely by the model when the optical effects of the aerosols are taken into

  2. Lidar Observations of Stratospheric Aerosol Layer After the Mt. Pinatubo Volcanic Eruption

    NASA Technical Reports Server (NTRS)

    Nagai, Tomohiro; Uchino, Osamu; Fujimoto, Toshifumi

    1992-01-01

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

  3. Ozone and secondary aerosol formation — Analysis of particle observations in the 2009 SHARP campaign

    NASA Astrophysics Data System (ADS)

    Cowin, J.; Yu, X.; Laulainen, N.; Iedema, M.; Lefer, B. L.; Anderson, D.; Pernia, D.; Flynn, J. H.

    2010-12-01

    Particulate matters (PM) play important roles in the formation and transformation of ozone. Although photooxidation of volatile organic compounds with respect to ozone formation in the gas phase is well understood, many unknowns still exist in heterogeneous mechanisms that process soot, secondary aerosols (both inorganic and organic), and key radical precursors such as formaldehyde and nitrous acid. Our main objective is to answer two key science questions: 1) will reduction of fine PM reduce ozone formation? 2) What sources of PM are most culpable? Are they from local chemistry or long-range transport? The field data collected in the 2009 Study of Houston Atmospheric Radical Precursors (SHARP) by our group at the Moody Tower consist of 1) real-time photolysis rates of ozone precursors, 2) particle size distributions, 3) organic carbon and elemental carbon, and 4) an archive of single particle samples taken with the Time Resolved Aerosol Collector (TRAC) sampler. The time resolution of the TRAC sampler is 30 minutes for routine measurements, and 15 minutes during some identified “events” (usually in the mid-afternoon) of high ozone and secondary organic or sulfate particle formation. The latter events last typically about an hour. Five ozone exceedance days occurred during the 6 weeks of deployment. Strong correlation between photochemical activities and organic carbon was observed. Initial data analysis indicates that secondary organic aerosol is a major component of the carbonaceous aerosols observed in Houston. Soot, secondary sulfate, seal salt, and mineral dust particles are determined from single particle analysis using scanning electron microscope and transmission electron microcopy coupled with energy dispersive X-ray spectroscopy. Compared with observations in 2000, the mass percentage of organics is higher (60 vs. 30%), and lower for sulfate (20% vs. 32%). On-going data analysis will focus on the composition, sources, and transformation of primary and

  4. Observations and Modeling of 3-Dimensional Cloud and Aerosol Fields from the Multiangle SpectroPolarimetric Imager (MSPI)

    NASA Astrophysics Data System (ADS)

    Garay, M. J.; Diner, D. J.; Martonchik, J. V.; Davis, A. B.

    2011-12-01

    Knowledge of the detailed 3-dimensional structure of clouds and atmospheric aerosols is vital for correctly modeling their radiative effects and interpreting optical remote sensing measurements of scattered sunlight. We will describe a set of new observations made by the Multiangle SpectroPolarimetric Imager (MSPI) from the ground and from the NASA ER-2 aircraft. MSPI is being developed and tested at JPL as a payload for the preliminary Aerosol-Cloud-Ecosystems (PACE) satellite mission, which is expected to fly near the end of the decade. MSPI builds upon experience gained from the Multi-angle Imaging SpectroRadiometer (MISR) currently orbiting on NASA's Terra satellite. Ground-MSPI and Air-MSPI are two prototype cameras operating in the ultraviolet (UV) to the visible/near-infrared (VNIR) range mounted on gimbals that acquire imagery in a pushbroom fashion, including polarization in selected spectral bands with demonstrated high polarimetric accuracy (0.5% uncertainty in degree of linear polarization). The spatial resolution of Ground-MSPI is 1 m for objects at a distance of 3 km. From the operational altitude of the ER-2, Air-MSPI has a ground resolution of approximately 10 m at nadir. This resolution, coupled with good calibration and high polarimetric performance means that MSPI can be used to derive radiatively important parameters of aerosols and clouds using intensity and polarization information together. As part of the effort for developing retrieval algorithms for the instrument, we have employed an extremely flexible 3-dimensional vector radiative transfer code. We will show example imagery from both MSPI cameras and describe how these scenes are modeled using this code. We will also discuss some of the important unknowns and limitations of this observational approach.

  5. The Global Aerosol Synthesis and Science Project (GASSP): Using a Comprehensive Synthesis of Aerosol Observations and Statistical Modelling to Constrain Model Uncertainty

    NASA Astrophysics Data System (ADS)

    Reddington, C.; Lee, L.; Carslaw, K. S.; Liu, D.; Allan, J. D.; Coe, H.; Pringle, K.; Stier, P.; Partridge, D.; Schutgens, N.

    2014-12-01

    Over the past few decades there has been enormous investment in atmospheric aerosol measurements across the globe. However, ultimately only a small fraction of these measurements are used to test and improve models. GASSP aims to bring together as much aerosol measurement data as possible in combination with a novel application of statistical methods to test and improve atmospheric model processes and improve our understanding of global aerosol and climate. Presently, we have synthesised a vast array of diverse aerosol measurements from aircraft, ground stations and ships, combining campaign and long-term measurements conducted over the past two decades. These data include in-situ measurements of cloud condensation nuclei and aerosol particle number concentrations, sizes and chemical composition. By combining different aerosol measurements we can ensure that the model skill is consistent across a range of aerosol properties in a range of environments. We will present spatial maps and time series of these data, identifying key regions where gaps currently exist in the dataset and where future contribution from the measurement community will be most crucial. We have also performed a sensitivity analysis of the output from a global aerosol model, which has identified the important sources of parameter uncertainty in all model grid cells throughout a single year. Cluster analysis of this data shows which model uncertainties can be constrained by observations in any particular global region during the year. Similarities and distinctions between clusters allows us to identify how observations made around the globe have the potential to constrain the global aerosol model and identify which model uncertainties will remain irreducible with the current suite of observations. As a first step we have used synthetic observations to constrain the model uncertainties and quantify the potential of real observations for model constraint. We then use these results to target real

  6. Radial inhomogeneities in particle composition of single, levitated aerosol particles observed by Mie resonance spectroscopy (Invited)

    NASA Astrophysics Data System (ADS)

    Krieger, U. K.; Steimer, S.; Lienhard, D.; Bastelberger, S.

    2013-12-01

    Recent observations have indicated that organic aerosol particles in the atmosphere may exist in an amorphous semi-solid or even solid (i.e. glassy) state, e.g. [1]. The influence of highly viscous and glassy states on the timescale of aerosol particle equilibration with respect to water vapor have been investigated for some model systems of atmospheric aerosol, e.g. [2,3]. In particular, it has been shown that the kinetics of the water absorption/desorption process is controlled entirely by liquid-phase diffusion of water molecules for a highly viscous aerosol particle. A liquid phase diffusion model based on numerically solving the non-linear diffusion equation predicts strong internal gradients in water concentration when condensed phase diffusion impedes the water uptake from the gas phase [2]. Here we observe and quantify the internal concentration gradients in single, levitated, micron size aerosol particles of aqueous MBTCA (3-methyl-1,2,3-Butanetricarboxylic acid) and shikimic acid using elastic Mie resonance spectroscopy. A single, aqueous particle is levitated in an electro-dynamic balance (for details see [2]), dried for several days at room temperature, cooled to the target temperature and exposed to a rapid change in relative humidity. In addition to measuring the elastically backscattered light of a 'white light ' LED source and recording the full spectrum with a spectrograph as in [2], we use a tunable diode laser (TDL) to scan high resolution TE- and TM spectra. This combination allows observing various Mie resonance mode orders simultaneously. Since we perform the experiment at low temperatures and low humidities the changes in the Mie-spectra due to water uptake are sufficiently slow to resolve the kinetics. Experimental Mie resonance spectra are inverted to concentration profiles of water within the particle by applying the numerical diffusion model [2] in conjunction with Mie calculations of multilayered spheres [4]. Potential implications for

  7. Inhomogeneities in particle composition of single, levitated aerosol particles observed by Mie resonance spectroscopy

    NASA Astrophysics Data System (ADS)

    Krieger, Ulrich; Lienhard, Daniel; Bastelberger, Sandra; Steimer, Sarah

    2014-05-01

    Recent observations have indicated that organic aerosol particles in the atmosphere may exist in an amorphous semi-solid or even solid (i.e. glassy) state, e.g. [1]. The influence of highly viscous and glassy states on the timescale of aerosol particle equilibration with respect to water vapor have been investigated for some model systems of atmospheric aerosol, e.g. [2,3]. In particular, it has been shown that the kinetics of the water absorption/desorption process is controlled entirely by liquid-phase diffusion of water molecules for a highly viscous aerosol particle. A liquid phase diffusion model based on numerically solving the non-linear diffusion equation predicts strong internal gradients in water concentration when condensed phase diffusion impedes the water uptake from the gas phase [2]. Here we observe and quantify the internal concentration gradients in single, levitated, micron size aerosol particles of aqueous shikimic acid using elastic Mie resonance spectroscopy. A single, aqueous particle is levitated in an electro-dynamic balance (for details see [2]), dried for several days at room temperature, cooled to the target temperature and exposed to a rapid change in relative humidity. In addition to measuring the elastically backscattered light of a "white light" LED source and recording the full spectrum with a spectrograph as in [2], we use a tunable diode laser (TDL) to scan high resolution TE- and TM spectra. This combination allows observing various Mie resonance mode orders simultaneously. Since we perform the experiment at low temperatures and low humidities the changes in the Mie-spectra due to water uptake are sufficiently slow to resolve the kinetics. Experimental Mie resonance spectra are inverted to concentration profiles of water within the particle by applying the numerical diffusion model [2] in conjunction with Mie calculations of multilayered spheres [4]. [1] A. Virtanen et al. (2010): An amorphous solid state of biogenic secondary

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

    NASA Astrophysics Data System (ADS)

    Wagner, N. L.; Brock, C. A.; Angevine, W. M.; Beyersdorf, A.; Campuzano-Jost, P.; Day, D. 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.

  9. What We Can Learn About Aerosols from EOS-MISR Multi-Angle Remote Sensing Observations Over Ocean

    NASA Technical Reports Server (NTRS)

    Kahn, R.

    1999-01-01

    Multiangle, multispectral remote sensing observations, such as those anticipated from the Earth Observing System (EOS) Multiangle Imaging SpectroRadiometer (MISR), promise to significantly improve our ability to constrain aerosol properties from space.

  10. Evolution of the Physicochemical and Activation Properties of Aerosols within Smoke Plumes during the Biomass Burning Observation Project (BBOP)

    NASA Astrophysics Data System (ADS)

    Tomlinson, J. M.; Mei, F.; Wang, J.; Comstock, J. M.; Hubbe, J. M.; Pekour, M. S.; Shilling, J. E.; Fortner, E.; Chand, D.; Sedlacek, A. J., III; Kleinman, L. I.; Senum, G.; Schmid, B.

    2014-12-01

    Biomass burning from wildfires and controlled agricultural burns are known to be a major source of fine particles and organic aerosols at northern temperate latitudes during the summer months. However, the evolution of the physicochemical properties of the aerosol during transport and the potential impact of this evolution on cloud condensation nuclei (CCN) activity has rarely been studied for these events. During the DOE-sponsored Biomass Burning Observation Project (BBOP) conducted in the summer and fall of 2013, over 30 research flights sampled biomass burning plumes from wildfires in the Northwestern United States and agricultural burns in the Mid-South region of the United States. A large suite of instruments aboard the DOE G-1 (Gulfstream-1) measured the chemical, physical, and optical properties of biomass burning aerosol with an emphasis on black carbon. A Fast Integrated Mobility Spectrometer (FIMS), Ultra High Sensitivity Aerosol Spectrometer - Airborne (UHSAS-A), and Passive Cavity Aerosol Spectrometer (PCASP) were used to measure the aerosol size distribution from 15 - 3,000 nm at 1-Hz. A dual column CCN counter measured the CCN number concentration at supersaturations of 0.25% and 0.50% at a time resolution of 1-Hz and the aerosol chemical composition was measured using a soot particle aerosol mass spectrometer (SP-AMS, Aerodyne, Inc). The SP-AMS was operated in two modes: (i) as a traditional high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS, Aerodyne Inc.), which measured chemical composition of non-refractory aerosols and (ii) as the SP-AMS which measured chemical composition of the refractory black carbon-containing (rBC) particle coating and rBC aerosol mass. Utilizing the aforementioned measurements, a CCN closure study is used to investigate the emitted aerosol hygroscopicity, the evolution of the physicochemical properties of the aerosol, and the potential impacts on cloud microphysics from the different fuel sources.

  11. Seasonal variability in aerosol, CCN and their relationship observed at a high altitude site in Western Ghats

    NASA Astrophysics Data System (ADS)

    Leena, P. P.; Pandithurai, G.; Anilkumar, V.; Murugavel, P.; Sonbawne, S. M.; Dani, K. K.

    2016-04-01

    Atmospheric aerosols which serve as cloud condensation nuclei (CCN) are key elements of the hydrological cycle and climate. In the present work, aerosol-CCN variability and their relationship have been studied for the first time at Mahabaleshwar, a high altitude (1348 m AMSL) site in Western Ghats, using one year (June 2012-May 2013) of observations. Present study has been done in two sections in which first temporal variability (diurnal and seasonal) of aerosol and CCN has been analyzed. Later CCN to aerosol ratio and other microphysical properties have been investigated along with detail discussion on possible sources of aerosol. First part, i.e., diurnal variation in aerosol and CCN concentration has shown relatively higher values during early morning hours in monsoon season whereas in winter and pre-monsoon it was higher in the evening hours. Seasonal mean variation in aerosol and CCN (SS above 0.6 %) has shown higher (less) in monsoon (winter) season. Temporal variation reveals dominance of fine-mode aerosol during monsoon season over the study region. In the second part temporal variation of activation ratio, k value (exponent of CCN super-saturation spectra) and geometric mean aerosol diameter have been analyzed. Variation of activation ratio showed the ratio is higher in monsoon especially for SS 0.6-1 %. The analysis also showed high k value during monsoon season as compared to other seasons (pre-monsoon and winter) which may be due to dominance of hygroscopic aerosols in the maritime air masses from Arabian Sea and biogenic aerosol emissions from the wet forest. Analyzed mean aerosol diameter is much smaller during monsoon season with less variability compared to other seasons. Overall analysis showed that aerosol and CCN concentration was higher over this high altitude site despite of dominant sink processes such as cloud scavenging and washout mechanisms indicating local emissions and biogenic Volatile Organic Compounds (BVOC) emissions from wet forest

  12. Aerosol impacts on deep convective storms in the tropics: A combination of modeling and observations

    NASA Astrophysics Data System (ADS)

    Storer, Rachel Lynn

    It is widely accepted that increasing the number of aerosols available to act as cloud condensation nuclei (CCN) will have significant effects on cloud properties, both microphysical and dynamical. This work focuses on the impacts of aerosols on deep convective clouds (DCCs), which experience more complicated responses than warm clouds due to their strong dynamical forcing and the presence of ice processes. Several previous studies have seen that DCCs may be invigorated by increasing aerosols, though this is not the case in all scenarios. The precipitation response to increased aerosol concentrations is also mixed. Often precipitation is thought to decrease due to a less efficient warm rain process in polluted clouds, yet convective invigoration would lead to an overall increase in surface precipitation. In this work, modeling and observations are both used in order to enhance our understanding regarding the effects of aerosols on DCCs. Specifically, the area investigated is the tropical East Atlantic, where dust from the coast of Africa frequently is available to interact with convective storms over the ocean. The first study investigates the effects of aerosols on tropical DCCs through the use of numerical modeling. A series of large-scale, two-dimensional cloud-resolving model simulations was completed, differing only in the concentration of aerosols available to act as CCN. Polluted simulations contained more deep convective clouds, wider storms, higher cloud tops and more convective precipitation across the entire domain. Differences in the warm cloud microphysical processes were largely consistent with aerosol indirect theory, and the average precipitation produced in each DCC column decreased with increasing aerosol concentration. A detailed microphysical budget analysis showed that the reduction in collision and coalescence largely dominated the trend in surface precipitation; however the production of rain through the melting of ice, though it also

  13. Aerosol-Cloud Interactions in the South-East Atlantic: Knowledge Gaps, Planned Observations to Address Them, and Implications for Global Climate Change Modeling

    NASA Technical Reports Server (NTRS)

    Redemann, Jens; Wood, R.; Zuidema, P.; Haywood, J.; Luna, B.; Abel, S.

    2015-01-01

    Southern Africa produces almost a third of the Earth's biomass burning (BB) aerosol particles, yet the fate of these particles and their influence on regional and global climate is poorly understood. Particles lofted into the mid-troposphere are transported westward over the South-East (SE) Atlantic, home to one of the three permanent subtropical Stratocumulus (Sc) cloud decks in the world. The stratocumulus "climate radiators" are critical to the regional and global climate system. They interact with dense layers of BB aerosols that initially overlay the cloud deck, but later subside and are mixed into the clouds. These interactions include adjustments to aerosol-induced solar heating and microphysical effects. As emphasized in the latest IPCC report, the global representation of these aerosol-cloud interaction processes in climate models is one of the largest uncertainty in estimates of future climate. Hence, new observations over the SE Atlantic have significant implications for global climate change scenarios. We discuss the current knowledge of aerosol and cloud property distributions based on satellite observations and sparse suborbital sampling, and describe planned field campaigns in the region. Specifically, we describe the scientific objectives and implementation of the following four synergistic, international research activities aimed at providing a process-level understanding of aerosol-cloud interactions over the SE Atlantic: 1) ORACLES (Observations of Aerosols above Clouds and their interactions), a five-year investigation between 2015 and 2019 with three Intensive Observation Periods (IOP), recently funded by the NASA Earth-Venture Suborbital Program, 2) CLARIFY-2016 (Cloud-Aerosol-Radiation Interactions and Forcing: Year 2016), a comprehensive observational and modeling programme funded by the UK's Natural Environment Research Council (NERC), and supported by the UK Met Office. 3) LASIC (Layered Atlantic Smoke Interactions with Clouds), a funded

  14. Aerosol-cloud interactions in the South-East Atlantic: knowledge gaps, planned observations to address them, and implications for global climate change modeling

    NASA Astrophysics Data System (ADS)

    Redemann, Jens; Wood, Robert; Zuidema, Paquita; Haywood, James; Luna, Bernadette; Abel, Steven

    2015-04-01

    Southern Africa produces almost a third of the Earth's biomass burning (BB) aerosol particles, yet the fate of these particles and their influence on regional and global climate is poorly understood. Particles lofted into the mid-troposphere are transported westward over the South-East (SE) Atlantic, home to one of the three permanent subtropical Stratocumulus (Sc) cloud decks in the world. The stratocumulus "climate radiators" are critical to the regional and global climate system. They interact with dense layers of BB aerosols that initially overlay the cloud deck, but later subside and are mixed into the clouds. These interactions include adjustments to aerosol-induced solar heating and microphysical effects. As emphasized in the latest IPCC report, the global representation of these aerosol-cloud interaction processes in climate models is one of the largest uncertainty in estimates of future climate. Hence, new observations over the SE Atlantic have significant implications for global climate change scenarios. We discuss the current knowledge of aerosol and cloud property distributions based on satellite observations and sparse suborbital sampling, and describe planned field campaigns in the region. Specifically, we describe the scientific objectives and implementation of the following four synergistic, international research activities aimed at providing a process-level understanding of aerosol-cloud interactions over the SE Atlantic: 1) ORACLES (ObseRvations of Aerosols above CLouds and their intEractionS), a five-year investigation between 2015 and 2019 with three Intensive Observation Periods (IOP), recently funded by the NASA Earth-Venture Suborbital Program, 2) CLARIFY-2016 (CLoud-Aerosol-Radiation Interactions and Forcing: Year 2016), a comprehensive observational and modeling programme funded by the UK's Natural Environment Research Council (NERC), and supported by the UK Met Office. 3) LASIC (Layered Atlantic Smoke Interactions with Clouds), a funded

  15. Chemical and Physical Properties of Bulk Aerosols within Four Sectors Observed during TRACE-P

    NASA Technical Reports Server (NTRS)

    Jordan, C. E.; Anderson, B. E.; Talbot, R. W.; Dibb, J. E.; Fuelberg, E.; Hudgins, C. H.; Kiley, C. M.; Russo, R.; Scheuer, E.; Seid, G.

    2003-01-01

    Chemical and physical aerosol data collected on the DC-8 during TRACE-P were grouped into four sectors based on back trajectories. The four sectors represent long-range transport from the west (WSW), regional circulation over the western Pacific and Southeast Asia (SE Asia), polluted transport from Northern Asia with substantial sea salt at low altitudes (NNW) and a substantial amount of dust (Channel). WSW has generally low mixing ratios at both middle and high altitudes, with the bulk of the aerosol mass due to non-sea-salt water-soluble inorganic species. Low altitude SE Asia also has low mean mixing ratios in general, with the majority of the aerosol mass comprised of non-sea-salts, however, soot is also relatively important m this region. "w had the highest mean sea salt mixing ratios, with the aerosol mass at low altitudes (a km) evenly divided between sea salts, mm-sea-salts, and dust. The highest mean mixing ratios of water-soluble ions and soot were observed at the lowest altitudes (a km) in the Channel sector. The bulk of the aerosol mass exported from Asia emanates h m Channel at both low and midaltitudes, due to the prevalence of dust compared to other sectors. Number densities show enhanced fine particles for Channel and NNW, while their volume distributions are enhanced due to sea salt and dust Low-altitude Channel exhibits the highest condensation nuclei ((34) number densities along with enhanced scattering coefficients, compared to the other sectors. At midaltitudes (2-7 km), low mean CN number densities coupled with a high proportion of nonvolatile particles (265%) observed in polluted sectors (Channel and NNW) are attributed to wet scavenging which removes hygroscopic CN particles. Low single scatter albedo m SE Asia reflects enhanced soot

  16. Vertical Distribution of Gases and Aerosols in Titan's Atmosphere Observed by VIMS/Cassini Solar Occultations

    NASA Astrophysics Data System (ADS)

    Maltagliati, Luca; Vinatier, Sandrine; Sicardy, Bruno; Bézard, Bruno; Sotin, Christophe; Nicholson, Philip D.; Hedman, Matt; Brown, Robert H.; Baines, Kevin; Buratti, Bonnie; Clark, Robert

    2013-04-01

    We present the vertical distribution of gaseous species and aerosols in Titan's atmosphere through the analysis of VIMS solar occultations. We employ the infrared channel of VIMS, which covers the 1 - 5 μm wavelength range. VIMS occultations can provide good vertical resolution (~10 km) and an extended altitude range (from 70 to 700 km), complementing well the information from other Cassini instruments. VIMS has retrieved 10 solar occultations up to now. They are distributed through the whole Cassini mission and they probe different latitudes in both hemispheres. Two main gases can be observed by VIMS occultations: methane, through its bands at 1.2, 1.4, 1.7, 2.3 and 3.3 μm, and CO, at 4.7 μm. We can extract methane's abundance between 70 and 750 km and CO's between 70 and 180 km. Regarding aerosols, the VIMS altitude range allows to get information on the properties of both the main haze and the detached layer. Aerosols also affect the transmittance through their spectral signatures. In particular, a spectral signature at 3.4 μm that was attributed to aerosols was recently discovered by the analysis of the first VIMS occultation. We will monitor the latitudinal and temporal variations of the 3.4 μm feature through various occultations. A change in the global circulation regime of Titan sets in with the approaching to the vernal equinox, and a strong decrease of the altitude of the detached layer between the winter solstice and the equinox has indeed been observed. The temporal coverage of VIMS occultations allows the study the effect of these variations in the vertical distribution of aerosol optical and spectral properties.

  17. Chemical and physical properties of bulk aerosols within four sectors observed during TRACE-P

    NASA Astrophysics Data System (ADS)

    Jordan, C. E.; Anderson, B. E.; Talbot, R. W.; Dibb, J. E.; Fuelberg, H. E.; Hudgins, C. H.; Kiley, C. M.; Russo, R.; Scheuer, E.; Seid, G.; Thornhill, K. L.; Winstead, E.

    2003-11-01

    Chemical and physical aerosol data collected on the DC-8 during TRACE-P were grouped into four sectors based on back trajectories. The four sectors represent long-range transport from the west (WSW), regional circulation over the western Pacific and Southeast Asia (SE Asia), polluted transport from northern Asia with substantial sea salt at low altitudes (NNW) and a substantial amount of dust (Channel). WSW has generally low mixing ratios at both middle and high altitudes, with the bulk of the aerosol mass due to non-sea-salt water-soluble inorganic species. Low altitude SE Asia also has low mean mixing ratios in general, with the majority of the aerosol mass comprised of non-sea-salts, however, soot is also relatively important in this region. NNW had the highest mean sea salt mixing ratios, with the aerosol mass at low altitudes (<2 km) evenly divided between sea salts, non-sea-salts, and dust. The highest mean mixing ratios of water-soluble ions and soot were observed at the lowest altitudes (<2 km) in the Channel sector. The bulk of the aerosol mass exported from Asia emanates from Channel at both low and midaltitudes, due to the prevalence of dust compared to other sectors. Number densities show enhanced fine particles for Channel and NNW, while their volume distributions are enhanced due to sea salt and dust. Low-altitude Channel exhibits the highest condensation nuclei (CN) number densities along with enhanced scattering coefficients, compared to the other sectors. At midaltitudes (2-7 km), low mean CN number densities coupled with a high proportion of nonvolatile particles (≥65%) observed in polluted sectors (Channel and NNW) are attributed to wet scavenging which removes hygroscopic CN particles. Low single scatter albedo in SE Asia reflects enhanced soot.

  18. Global aerosol typing from a combination of A-Train satellite observations in clear-sky and above clouds

    NASA Astrophysics Data System (ADS)

    Kacenelenbogen, M. S.; Russell, P. B.; Vaughan, M.; Redemann, J.; Shinozuka, Y.; Livingston, J. M.; Zhang, Q.

    2014-12-01

    According to the 5th Assessment Report of the Intergovernmental Panel on Climate Change (IPCC), the model estimates of Radiative Forcing due to aerosol-radiation interactions (RFari) for individual aerosol types are less certain than the total RFari [Boucher et al., 2013]. For example, the RFari specific to Black Carbon (BC) is uncertain due to an underestimation of its mass concentration near source regions [Koch et al., 2009]. Several recent studies have evaluated chemical transport model (CTM) predictions using observations of aerosol optical properties such as Aerosol Optical Depth (AOD) or Single Scattering Albedo (SSA) from satellite or ground-based instruments (e.g., Huneeus et al., [2010]). However, most passive remote sensing instruments fail to provide a comprehensive assessment of the particle type without further analysis and combination of measurements. To improve the predictions of aerosol composition in CTMs, we have developed an aerosol classification algorithm (called Specified Clustering and Mahalanobis Classification, SCMC) that assigns an aerosol type to multi-parameter retrievals by spaceborne, airborne or ground based passive remote sensing instruments [Russell et al., 2014]. The aerosol types identified by our scheme are pure dust, polluted dust, urban-industrial/developed economy, urban-industrial/developing economy, dark biomass smoke, light biomass smoke and pure marine. First, we apply the SCMC method to five years of clear-sky space-borne POLDER observations over Greece. We then use the aerosol extinction and SSA spectra retrieved from a combination of MODIS, OMI and CALIOP clear-sky observations to infer the aerosol type over the globe in 2007. Finally, we will extend the spaceborne aerosol classification from clear-sky to above low opaque water clouds using a combination of CALIOP AOD and backscatter observations and OMI absorption AOD values from near-by clear-sky pixels.

  19. Direct radiative feedback due to biogenic secondary organic aerosol estimated from boreal forest site observations

    NASA Astrophysics Data System (ADS)

    Lihavainen, Heikki; Asmi, Eija; Aaltonen, Veijo; Makkonen, Ulla; Kerminen, Veli-Matti

    2015-10-01

    We used more than five years of continuous aerosol measurements to estimate the direct radiative feedback parameter associated with the formation of biogenic secondary organic aerosol (BSOA) at a remote continental site at the edge of the boreal forest zone in Northern Finland. Our upper-limit estimate for this feedback parameter during the summer period (ambient temperatures above 10 °C) was -97 ± 66 mW m-2 K-1 (mean ± STD) when using measurements of the aerosol optical depth (fAOD) and -63 ± 40 mW m-2 K-1 when using measurements of the ‘dry’ aerosol scattering coefficient at the ground level (fσ). Here STD represents the variability in f caused by the observed variability in the quantities used to derive the value of f. Compared with our measurement site, the magnitude of the direct radiative feedback associated with BSOA is expected to be larger in warmer continental regions with more abundant biogenic emissions, and even larger in regions where biogenic emissions are mixed with anthropogenic pollution.

  20. Non-Spherical Aerosol Phase Functions Derived from MODIS and AERONET Observations

    NASA Technical Reports Server (NTRS)

    Remer, L. A.; Kaufman, Y. J.; Levy, R. C.; Dubovik, O.; Lau, William K. M. (Technical Monitor)

    2002-01-01

    We compare MODIS (Moderate Resolution Imaging Spectroradiometer) satellite aerosol retrievals of spectral optical thickness and size parameters over ocean with the same quantities derived from AERONET (Aerosol Robotic Network) observations made at island and coastal sites. Over much of the globe, the satellite-derived quantities agree well with the AERONET quantities. However, in regimes dominated by desert dust aerosol, the agreement is less robust. In the dust regimes, the MODIS retrievals show greater spectral dependence and report smaller particle sizes than do the AERONET derivations. We suggest that the reason for this discrepancy is the nonspherical nature of desert dust particles, which the initial MODIS algorithm is not able to handle. Using the discrepancy between MODIS and AERONET derived spectral optical thickness as an asset, instead of a detriment, we reconstruct the aerosol phase functions that the MODIS algorithm would have needed in order to match the AERONET retrievals. No assumptions of particle shape are used in the derivation of these functions and the results are empirical total column, ambient phase functions. We compare the empirically derived phase functions with phase functions calculated from spheres and spheroids, both situations in which assumptions about particle shape must be made. The resulting empirical nonspherical phase functions will be included in future updates of the MODIS algorithm.

  1. Observed aerosol optical depth and angstrom exponent in urban area of Nanjing, China

    NASA Astrophysics Data System (ADS)

    Li, Shu; Wang, Tijian; Xie, Min; Han, Yong; Zhuang, Bingliang

    2015-12-01

    Aerosol optical properties at Gulou station in Nanjing, China were measured and analyzed from April 2011 to April 2012. The annual median of aerosol optical depth (hereafter called as AOD) at 440 nm was 0.73 and the corresponding annual median of angstrom exponent (hereafter called as AE) between 440 nm and 870 nm was 1.28. The monthly median of AOD440nm presented a seasonal variation, which revealed a maximum in August (1.22) and a minimum in February (0.51), while the monthly median of AE showed a minimum in May (0.79) and a maximum in December (1.42). AOD and AE accumulated mainly between 0.40-0.90 (68%) and 1.20-1.50 (68%) respectively in Nanjing. The observation data showed that high AODs (>1.00) were clustered in the fine mode growth wing and the coarse mode. Comparison was made between two typical cases under different weather conditions and the results showed that Nanjing is influenced by the dust aerosol from Northwest China and Mongolia under dust weather in spring and the anthropogenic aerosol from local emission and surrounding industrialization region under haze weather.

  2. Substantial secondary organic aerosol formation in a coniferous forest: observations of both day- and nighttime chemistry

    NASA Astrophysics Data System (ADS)

    Lee, Alex K. Y.; Abbatt, Jonathan P. D.; Leaitch, W. Richard; Li, Shao-Meng; Sjostedt, Steve J.; Wentzell, Jeremy J. B.; Liggio, John; Macdonald, Anne Marie

    2016-06-01

    Substantial biogenic secondary organic aerosol (BSOA) formation was investigated in a coniferous forest mountain region in Whistler, British Columbia. A largely biogenic aerosol growth episode was observed, providing a unique opportunity to investigate BSOA formation chemistry in a forested environment with limited influence from anthropogenic emissions. Positive matrix factorization of aerosol mass spectrometry (AMS) measurement identified two types of BSOA (BSOA-1 and BSOA-2), which were primarily generated by gas-phase oxidation of monoterpenes and perhaps sesquiterpenes. The temporal variations of BSOA-1 and BSOA-2 can be explained by gas-particle partitioning in response to ambient temperature and the relative importance of different oxidation mechanisms between day and night. While BSOA-1 arises from gas-phase ozonolysis and nitrate radical chemistry at night, BSOA-2 is likely less volatile than BSOA-1 and consists of products formed via gas-phase oxidation by OH radical and ozone during the day. Organic nitrates produced through nitrate radical chemistry can account for 22-33 % of BSOA-1 mass at night. The mass spectra of BSOA-1 and BSOA-2 have higher values of the mass fraction of m/z 91 (f91) compared to the background organic aerosol. Using f91 to evaluate BSOA formation pathways in this unpolluted, forested region, heterogeneous oxidation of BSOA-1 is a minor production pathway of BSOA-2.

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

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

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

  4. Microphysical, Macrophysical and Radiative Signatures of Volcanic Aerosols in Trade Wind Cumulus Observed by the A-Train

    NASA Technical Reports Server (NTRS)

    Yuan, T.; Remer, L. A.; Yu, H.

    2011-01-01

    Increased aerosol concentrations can raise planetary albedo not only by reflecting sunlight and increasing cloud albedo, but also by changing cloud amount. However, detecting aerosol effect on cloud amount has been elusive to both observations and modeling due to potential buffering mechanisms and convolution of meteorology. Here through a natural experiment provided by long-tem1 degassing of a low-lying volcano and use of A-Train satellite observations, we show modifications of trade cumulus cloud fields including decreased droplet size, decreased precipitation efficiency and increased cloud amount are associated with volcanic aerosols. In addition we find significantly higher cloud tops for polluted clouds. We demonstrate that the observed microphysical and macrophysical changes cannot be explained by synoptic meteorology or the orographic effect of the Hawaiian Islands. The "total shortwave aerosol forcin", resulting from direct and indirect forcings including both cloud albedo and cloud amount. is almost an order of magnitude higher than aerosol direct forcing alone. Furthermore, the precipitation reduction associated with enhanced aerosol leads to large changes in the energetics of air-sea exchange and trade wind boundary layer. Our results represent the first observational evidence of large-scale increase of cloud amount due to aerosols in a trade cumulus regime, which can be used to constrain the representation of aerosol-cloud interactions in climate models. The findings also have implications for volcano-climate interactions and climate mitigation research.

  5. Chemical Nature Of Titan’s Organic Aerosols Constrained from Spectroscopic and Mass Spectrometric Observations

    NASA Astrophysics Data System (ADS)

    Imanaka, Hiroshi; Cruikshank, D. P.

    2012-10-01

    The Cassini-Huygens observations greately extend our knowledge about Titan’s organic aerosols. The Cassini INMS and CAPS observations clearly demonstrate the formation of large organic molecules in the ionosphere [1, 2]. The VIMS and CIRS instruments have revealed spectral features of the haze covering the mid-IR and far-IR wavelengths [3, 4, 5, 6]. This study attempts to speculate the possible chemical nature of Titan’s aerosols by comparing the currently available observations with our laboratory study. We have conducted a series of cold plasma experiment to investigate the mass spectrometric and spectroscopic properties of laboratory aerosol analogs [7, 8]. Titan tholins and C2H2 plasma polymer are generated with cold plasma irradiations of N2/CH4 and C2H2, respectively. Laser desorption mass spectrum of the C2H2 plasma polymer shows a reasonable match with the CAPS positive ion mass spectrum. Furthermore, spectroscopic features of the the C2H2 plasma polymer in mid-IR and far-IR wavelegths qualitatively show reasonable match with the VIMS and CIRS observations. These results support that the C2H2 plasma polymer is a good candidate material for Titan’s aerosol particles at the altitudes sampled by the observations. We acknowledge funding supports from the NASA Cassini Data Analysis Program, NNX10AF08G, and from the NASA Exobiology Program, NNX09AM95G, and the Cassini Project. [1] Waite et al. (2007) Science 316, 870-875. [2] Crary et al. (2009) Planet. Space Sci. 57, 1847-1856. [3] Bellucci et al. (2009) Icarus 201, 198-216. [4] Anderson and Samuelson (2011) Icarus 212, 762-778. [5] Vinatier et al. (2010) Icarus 210, 852-866. [6] Vinatier et al. (2012) Icarus 219, 5-12. [7] Imanaka et al. (2004) Icarus 168, 344-366. [8] Imanaka et al. (2012) Icarus 218, 247-261.

  6. Dust aerosol optical depth and altitude retrieved from 7 years of infrared sounders observations (AIRS, IASI) and comparison with other aerosol datasets (MODIS, CALIOP, PARASOL)

    NASA Astrophysics Data System (ADS)

    Peyridieu, Sophie; Chédin, Alain; Tanré, Didier; Capelle, Virginie; Pierangelo, Clémence; Lamquin, Nicolas; Armante, Raymond

    2010-05-01

    Remote sensing of aerosol properties in the visible domain has been widely used for a better characterization of these particles and of their effect on solar radiation. On the opposite, remote sensing of aerosols in the thermal infrared domain still remains marginal. However, knowledge of the effect of aerosols on terrestrial radiation is needed for the evaluation of their total radiative forcing. A key point of infrared remote sensing is its ability to retrieve aerosol optical depth as well as mean dust layer altitude, a variable required for measuring their impact on climate. Moreover, observations are possible night and day, over ocean and over land. Our algorithm is specifically designed to retrieve simultaneously coarse mode dust aerosol 10 µm optical depth (AOD) and mean layer altitude from high spectral resolution infrared sounders observations. Thanks to IASI higher spectral resolution, the selection of finer channels for aerosol detection allows an even more accurate determination of aerosol properties. In this context, results obtained from 7 years (2003-2010) of AIRS/Aqua and more than 2 years (2007-2010) of IASI/Metop observations have been compared to other aerosol sensors. Compared to MODIS/Aqua optical depth product, 10 µm dust optical depth shows a very good agreement, particularly for tropical Atlantic regions downwind of the Sahara during the dust season. Comparisons with PARASOL non-spherical coarse mode product allows explaining small differences observed far from the sources. Time series of the mean aerosol layer altitude are compared to the CALIOP Level-2 products starting June 2006. For regions located downwind of the Sahara, the comparison again shows a good agreement with a mean standard deviation between the two products of about 400 m over the period processed, demonstrating that our algorithm effectively allows retrieving accurate mean dust layer altitude. A 7-year global climatology of the aerosol 10 µm dust optical depth and of the

  7. Inter-annual variability of aerosol optical depth over the tropical Atlantic Ocean based on MODIS-Aqua observations over the period 2002-2012

    NASA Astrophysics Data System (ADS)

    Gkikas, Antonis; Hatzianastassiou, Nikolaos

    2013-04-01

    The tropical Atlantic Ocean is affected by dust and biomass burning aerosol loads transported from the western parts of the Saharan desert and the sub-Sahel regions, respectively. The spatial and temporal patterns of this transport are determined by the aerosol emission rates, their deposition (wet and dry), by the latitudinal shift of the Intertropical Convergence Zone (ITCZ) and the prevailing wind fields. More specifically, in summer, Saharan dust aerosols are transported towards the Atlantic Ocean, even reaching the Gulf of Mexico, while in winter the Atlantic Ocean transport takes place in more southern latitudes, near the equator, sometimes reaching the northern parts of South America. In the later case, dust is mixed with biomass burning aerosols originating from agricultural activities in the sub-Sahel, associated with prevailing north-easterly airflow (Harmattan winds). Satellite observations are the appropriate tool for describing this African aerosol export, which is important to atmospheric, oceanic and climate processes, offering the advantage of complete spatial coverage. In the present study, we use satellite measurements of aerosol optical depth at 550nm (AOD550nm), on a daily and monthly basis, derived from MODIS-Aqua platform, at 1ox1o spatial resolution (Level 3), for the period 2002-2012. The primary objective is to determine the pixel-level and regional mean anomalies of AOD550nm over the entire study period. The regime of the anomalies of African export is interpreted in relation to the aerosol source areas, precipitation, wind patterns and temporal variability of the North Atlantic Oscillation Index (NAOI). In order to ensure availability of AOD over the Sahara desert, MODIS-Aqua Deep Blue products are also used. As for precipitation, Global Precipitation Climatology Project (GPCP) data at 2.5ox2.5o are used. The wind fields are taken from the National Center for Environmental Prediction (NCEP). Apart from the regime of African aerosol export

  8. Vertical Distribution of Aerosols and Water Vapor Using CRISM Limb Observations

    NASA Astrophysics Data System (ADS)

    Smith, M. D.; Wolff, M. J.; Clancy, R. T.; CRISM Science; Operations Teams

    2011-12-01

    Near-infrared spectra taken in a limb-viewing geometry by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) on-board the Mars Reconnaissance Orbiter (MRO) provide a useful tool for probing atmospheric structure. Specifically, the observed radiance as a function of wavelength and height above the limb allows the vertical distribution of both dust and ice aerosols to be retrieved. These data serve as an important supplement to the aerosol profiling provided by the MRO/MCS instrument allowing independent validation and giving additional information on particle physical and scattering properties through multi-wavelength studies. A total of at least ten CRISM limb observations have been taken so far covering a full Martian year. Each set of limb observations nominally contains about four dozen scans across the limb giving pole-to-pole coverage for two orbits at roughly 100 and 290 W longitude over the Tharsis and Syrtis/Hellas regions, respectively. At each longitude, limb scans are spaced roughly 10 degrees apart in latitude, with a vertical spatial resolution on the limb of roughly 800 m. Radiative transfer modeling is used to model the observations. We compute synthetic CRISM limb spectra using a discrete-ordinates radiative transfer code that accounts for multiple scattering from aerosols and accounts for spherical geometry of the limb observations by integrating the source functions along curved paths in that coordinate system. Retrieved are 14-point vertical profiles for dust and water ice aerosols with resolution of 0.4 scale heights between one and six scale heights above the surface. After the aerosol retrieval is completed, the abundances of CO2 (or surface pressure) and H2O gas are retrieved by matching the depth of absorption bands at 2000 nm for carbon dioxide and at 2600 nm for water vapor. In addition to the column abundance of water vapor, limited information on its vertical structure can also be retrieved depending on the signal available

  9. 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.

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

    NASA Astrophysics Data System (ADS)

    van Diedenhoven, B.; Perlwitz, J. P.; Fridlind, A. M.; Chowdhary, J.; Cairns, B.; Stangl, A. J.

    2015-12-01

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

  11. 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

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

    NASA Technical Reports Server (NTRS)

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

    2015-01-01

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

  13. The importance of temporal collocation for the evaluation of aerosol models with observations

    NASA Astrophysics Data System (ADS)

    Schutgens, N. A. J.; Partridge, D. G.; Stier, P.

    2016-01-01

    It is often implicitly assumed that over suitably long periods the mean of observations and models should be comparable, even if they have different temporal sampling. We assess the errors incurred due to ignoring temporal sampling and show that they are of similar magnitude as (but smaller than) actual model errors (20-60 %).Using temporal sampling from remote-sensing data sets, the satellite imager MODIS (MODerate resolution Imaging Spectroradiometer) and the ground-based sun photometer network AERONET (AErosol Robotic NETwork), and three different global aerosol models, we compare annual and monthly averages of full model data to sampled model data. Our results show that sampling errors as large as 100 % in AOT (aerosol optical thickness), 0.4 in AE (Ångström Exponent) and 0.05 in SSA (single scattering albedo) are possible. Even in daily averages, sampling errors can be significant. Moreover these sampling errors are often correlated over long distances giving rise to artificial contrasts between pristine and polluted events and regions. Additionally, we provide evidence that suggests that models will underestimate these errors. To prevent sampling errors, model data should be temporally collocated to the observations before any analysis is made.We also discuss how this work has consequences for in situ measurements (e.g. aircraft campaigns or surface measurements) in model evaluation.Although this study is framed in the context of model evaluation, it has a clear and direct relevance to climatologies derived from observational data sets.

  14. Direct observation of aqueous secondary organic aerosol from biomass-burning emissions.

    PubMed

    Gilardoni, Stefania; Massoli, Paola; Paglione, Marco; Giulianelli, Lara; Carbone, Claudio; Rinaldi, Matteo; Decesari, Stefano; Sandrini, Silvia; Costabile, Francesca; Gobbi, Gian Paolo; Pietrogrande, Maria Chiara; Visentin, Marco; Scotto, Fabiana; Fuzzi, Sandro; Facchini, Maria Cristina

    2016-09-01

    The mechanisms leading to the formation of secondary organic aerosol (SOA) are an important subject of ongoing research for both air quality and climate. Recent laboratory experiments suggest that reactions taking place in the atmospheric liquid phase represent a potentially significant source of SOA mass. Here, we report direct ambient observations of SOA mass formation from processing of biomass-burning emissions in the aqueous phase. Aqueous SOA (aqSOA) formation is observed both in fog water and in wet aerosol. The aqSOA from biomass burning contributes to the "brown" carbon (BrC) budget and exhibits light absorption wavelength dependence close to the upper bound of the values observed in laboratory experiments for fresh and processed biomass-burning emissions. We estimate that the aqSOA from residential wood combustion can account for up to 0.1-0.5 Tg of organic aerosol (OA) per y in Europe, equivalent to 4-20% of the total OA emissions. Our findings highlight the importance of aqSOA from anthropogenic emissions on air quality and climate. PMID:27551086

  15. Cross-Characterization of Aerosol Properties from Multiple Spaceborne Sensors Facilitated by Regional Ground-Based Observations

    NASA Technical Reports Server (NTRS)

    Petrenko, Maksym; Ichoku, Charles; Leptoukh, Gregory

    2010-01-01

    Aerosol observations from space have become a standard source for retrieval of aerosol properties on both regional and global scales. Indeed, the large number of currently operational spaceborne sensors provides for unprecedented access to the most complete set of complimentary aerosol measurements ever to be available. Nonetheless, this resource remains under-utilized, largely due to the discrepancies and differences existing between the sensors and their aerosol products. To characterize the inconsistencies and bridge the gap that exists between the sensors, we have designed and implemented an online Multi-sensor Aerosol Products Sampling System (MAPSS) that facilitates the joint sampling of aerosol data from multiple sensors. MAPSS consistently samples aerosol products from multiple spaceborne sensors using a unified spatial and temporal resolution, where each dataset is sampled over Aerosol Robotic Network (AERONET) locations together with coincident AERONET data samples. In this way, MAPSS enables a direct cross-characterization and data integration between aerosol products from multiple sensors. Moreover, the well-characterized co-located ground-based AERONET data provides the basis for the integrated validation of these products.

  16. A ten-year global record of absorbing aerosols above clouds from OMI's near-UV observations

    NASA Astrophysics Data System (ADS)

    Jethva, Hiren; Torrres, Omar; Ahn, Changwoo

    2016-05-01

    Aerosol-cloud interaction continues to be one of the leading uncertain components of climate models, primarily due to the lack of an adequate knowledge of the complex microphysical and radiative processes associated with the aerosolcloud system. The situations when aerosols and clouds are found in the same atmospheric column, for instance, when light-absorbing aerosols such as biomass burning generated carbonaceous particles or wind-blown dust overlay low-level cloud decks, are commonly found over several regional of the world. Contrary to the cloud-free scenario over dark surface, for which aerosols are known to produce a net cooling effect (negative radiative forcing) on climate, the overlapping situation of absorbing aerosols over cloud can potentially exert a significant level of atmospheric absorption and produces a positive radiative forcing at top-of-atmosphere. The magnitude of direct radiative effects of aerosols above cloud depends directly on the aerosol loading, microphysical-optical properties of the aerosol layer and the underlying cloud deck, and geometric cloud fraction. We help in addressing this problem by introducing a novel product of optical depth of absorbing aerosols above clouds retrieved from near-UV observations made by the Ozone Monitoring Instrument (OMI) on board NASA's Aura platform. The presence of absorbing aerosols above cloud reduces the upwelling radiation reflected by cloud and produces a strong `color ratio' effect in the near-UV region, which can be unambiguously detected in the OMI measurements. Physically based on this effect, the OMACA algorithm retrieves the optical depths of aerosols and clouds simultaneously under a prescribed state of atmosphere. The algorithm architecture and results from a ten-year global record including global climatology of frequency of occurrence and above-cloud aerosol optical depth, and a discussion on related future field campaigns are presented.

  17. Genesis of elevated aerosol loading over the Indian region

    NASA Astrophysics Data System (ADS)

    Prijith, S. S.; Rao, P. V. N.; Mohan, Mannil

    2016-05-01

    Elevated aerosols assume importance as the diabatic heating due to aerosol absorption is more intense at higher altitudes where the atmosphere becomes thinner. Indian region, especially its central and northern latitudes, experiences significant loading of elevated aerosols during pre-monsoon and summer months. Genesis of elevated aerosol loading over Indian region is investigated in the present study, using multi-year satellite observations from Cloud Aerosol Lidar with Orthogonal Polarization (CALIOP) and Moderate Resolution Imaging Spectroradiometer (MODIS) along with reanalysis winds from MERRA. Central India is observed to have prominent aerosols loading at higher altitudes during pre-monsoon season, whereas it is during summer months over north-west India. Further analysis reveals that the elevated aerosols over Indian region in pre-monsoon and summer months are significantly contributed by transported mineral dust from the arid continental regions at west. In addition to the mineral dust advection, aerosols at higher altitudes over Indian region are enriched by strong convection and associated vertical transport of surface level aerosols. Vertical transport of aerosols observed over Indian region during pre-monsoon and summer months is aided by intense convergence at the surface level and divergence at the upper level. Moreover, aerosol source/sink strength estimated using aerosol flux continuity equation show significant aerosol production over central India during pre-monsoon. Strong vertical transport prevails during pre-monsoon uplifts the locally produced aerosols, with considerable anthropogenic fraction, to higher altitudes where their impacts would be more intense.

  18. Effects of microphysics and aerosols on TC Intensity and structure as seen from high resolution WRF simulations

    NASA Astrophysics Data System (ADS)

    Khain, A.; Lynn, B. H.

    2014-12-01

    We simulate Hurricane Irene (2011) that moved northward along the eastern coast of the United States and weakened much faster than was predicted. The minimum pressure in Irene occurred about 40 h later than the time of maximum wind speed. Simulations performed with WRF with the spectral bin microphysics (SBM) showed that both the weakening of Irene and the time shift between maximum of wind and the minimum of pressure were caused by the effects of aerosols leading to the intensification of convection at its periphery resulting in an increase in size. Irena was also simulated using different bulk-parameterization schemes. The dispersion of TC in simulations using different schemes is very high, which indicates high sensitivity of TC intensity to microphysical processes. Despite the fact that new bulk-parameterization schemes simulated TC intensity quite well, non of bulk-schemes were able to predict the time shift between maximum wind and minimum surface pressure. The plausible reason is a too weak sensitivity of bulk schemes to aerosols.

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

    NASA Astrophysics Data System (ADS)

    Lolli, Simone; Sauvage Laurent, Laurent

    2010-05-01

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

  20. Intercomparison of satellite aerosol retrieval algorithms based on the simulated measurements of the intensity and polarization of reflected solar light for various types of underlying surfaces

    NASA Astrophysics Data System (ADS)

    Kokhanovsky, Alexander

    2014-05-01

    instruments/algorithms using simulated data. Such retrievals should give the same AOT, although in practice, this is often not the case. Then there is a problem with the selection of the best performing algorithm/instrument for lack of a single reference measurement. In this presentation, we inter-compare several aerosol retrieval algorithms using synthetic radiative transfer calculations for a given (and known) atmospheric state for an assumed spectral surface reflectance. In particular, the retrievals are performed using synthetic double-view AATSR and multi-view MISR radiometric observations, and multi-view POLDER radio-polarimetric observations. It is found that other things being equal the most accurate retrievals are achieved, if not only the intensity but also the polarization of the reflected solar light is measured at several angles and spectral channels. This finding strongly endorses the launch of multi-angular polarimeters such as the planned 3MI instrument to be developed by European Space Agency for the EUMETSAT Polar System Second Generation (EPS-SG).

  1. Observations of Light-Absorbing Carbonaceous Aerosols in East and South Asia

    NASA Astrophysics Data System (ADS)

    Yoon, S.; Kim, S.; Choi, W.

    2013-05-01

    Light-absorbing aerosols, such as black carbon (BC), brown carbon and mineral dust, typically constitute a small fraction of ambient particle mass but can contribute to solar radiative forcing through absorption of solar radiation and heating of the absorbing aerosol layer. Besides the direct radiative effect, the heating can evaporate clouds and change the atmospheric dynamics. In this study, we investigate the optical and radiative properties of light-absorbing aerosols from ground-based and aircraft measurements in East and South Asia within the framework of UNEP Atmospheric Brown Cloud-Asia (ABC-Asia) project and Sustainable Atmosphere for the Kathmandu Valley (SusKat) campaign (December 2012 ~ February 2013). BC mass concentration, aerosol scattering and absorption coefficients measurements and radiative forcing calculations were performed at four sites: Gosan (Korea), Anmyeon (Korea), Hanimaadhoo (Maldives) and Pyramid (Nepal). No significant seasonal variations of aerosol properties, except for summer due to wet scavenging by rainfall, were observed in East Asia, whereas dramatic changes of light-absorbing aerosol properties were observed in South Asia between dry and wet monsoon periods. Although BC mass concentration in East Asia is generally higher than that observed in South Asia, BC mass concentration at Hanimaadhoo during winter dry monsoon is similar to that of East Asia. The observed solar absorption efficiency (absorption coefficient/extinction coefficient) at 550 nm at Gosan and Anmyeon is higher than that in Hanimaadhoo due to large portions of BC emission from fossil fuel combustion. Interestingly, solar absorption efficiency at Pyramid is 0.14, which is two times great than that in Hanimaadhoo and is about 40% higher than that in East Asia, though BC mass concentration at Pyramid is the lowest among four sites. Throughout the unmanned aerial vehicle experiment in Jeju, Korea during August-September 2008, long-range transport of aerosols from

  2. An intensive study on aerosol optical properties and affecting factors in Nanjing, China.

    PubMed

    Cui, Fenping; Chen, Mindong; Ma, Yan; Zheng, Jun; Zhou, Yaoyao; Li, Shizheng; Qi, Lu; Wang, Li

    2016-02-01

    The optical properties of aerosol as well as their impacting factors were investigated at a suburb site in Nanjing during autumn from 14 to 28 November 2012. More severe pollution was found together with lower visibility. The average scattering and absorption coefficients (Bsca and Babs) were 375.7 ± 209.5 and 41.6 ± 18.7 Mm(-1), respectively. Higher Ångström absorption and scattering exponents were attributed to the presence of more aged aerosol with smaller particles. Relative humidity (RH) was a key factor affecting aerosol extinction. High RH resulted in the impairment of visibility, with hygroscopic growth being independent of the dry extinction coefficient. The hygroscopic growth factor was 1.8 ± 1.2 with RH from 19% to 85%. Light absorption was enhanced by organic carbon (OC), elemental carbon (EC) and EC coatings, with contributions of 26%, 44% and 75% (532 nm), respectively. The Bsca and Babs increased with increasing N100 (number concentration of PM2.5 with diameter above 100 nm), PM1 surface concentration and PM2.5 mass concentration with good correlation. PMID:26969543

  3. Transport and Microphysics of Aerosols Released by Collapse and Fire of the World Trade Center on September 11, 2001 as Observed by AERONET and MISR

    NASA Astrophysics Data System (ADS)

    Stenchikov, G. L.; Diner, D.; Kahn, R.; Smirnov, A.; Holben, B.

    2005-12-01

    Atmospheric pollution has been studied intensively during the last several decades for its impact on climate, visibility, atmospheric chemistry, and public health. Here we consider the aftermath of the catastrophic aerosol release produced by the collapse of the World Trade Center (WTC) in New York City (NYC) on September 11, 2001. The north and south WTC buildings were attacked at 0846 EDT and 0903 EDT, respectively, on September 11, 2001. The collapse of the WTC South Tower at 0959 EDT followed by the crash of the North Tower at 1029 EDT instantaneously pulverized a vast amount of building material, that was reduced to dust and smoke in nearby streets and the atmosphere above. The remains of the WTC complex covered a 16-acre area known as Ground Zero. Intensive combustion continued until September 14, with temperatures occasionally exceeding 1000 C, producing a steady, elevated source of hazardous gases and aerosols. A detailed spatial and temporal description of the pollution fields' evolution is needed to fully understand their environmental and health impact, but many existing in situ aerosol monitoring stations in the vicinity of the WTC were completely plugged with dust immediately after the collapse. However, the aerosol plume was remotely sensed from the ground and from space. Here we combine numerical modeling of micrometeorological fields and pollution transport using the RAMS/HYPACT modeling system with AERONET and MISR retrievals, to realistically reconstruct plume evolution. AERONET collected plume data in NYC from the roof of the Goddard Institute for Space Studies (GISS) in Upper Manhattan. In NYC, aerosol optical depth was rather low until 1800 UTC on September 12; then it increased to ~0.3 (at 440 nm) by 2130 UTC. On September 13, the optical depth was slightly elevated in the morning and increased further beginning at 1700 UTC, reaching ~0.30 by 2000-2200 UTC. The angstrom exponent increased from 1.8 on September 12 to 2.2 in the late afternoon

  4. Transboundary secondary organic aerosol in western Japan: An observed limitation of the f44 oxidation indicator

    NASA Astrophysics Data System (ADS)

    Irei, Satoshi; Takami, Akinori; Sadanaga, Yasuhiro; Miyoshi, Takao; Arakaki, Takemitsu; Sato, Kei; Kaneyasu, Naoki; Bandow, Hiroshi; Hatakeyama, Shiro

    2015-11-01

    To obtain evidence for secondary organic aerosol formation during the long-range transport of air masses over the East China Sea, we conducted field measurements in March 2012 at the Fukue atmospheric monitoring station, Nagasaki, in western Japan. The relative abundance of m/z 44 in fine organic aerosol (f44) was measured by an Aerodyne aerosol chemical speciation monitor. The stable carbon isotope ratio (δ13C) of low-volatile water-soluble organic carbon (LV-WSOC) in the daily filter samples of total suspended particulate matter was also analyzed using an elemental-analyzer coupled with an isotope ratio mass spectrometer. Additionally, in situ measurements of NOx and NOy were performed using NOx and NOy analyzers. The measurements showed that, unlike the systematic trends observed in a previous field study, a scatter plot for δ13C of LV-WSOC versus f44 indicated a random variation. Comparison of f44 with the estimated photochemical age by the NOx/NOy ratio revealed that the random distribution of f44 values near 0.2 is likely an indication of saturation already. Such f44 values were significantly lower than the observed f44 (∼0.3) at Hedo in the previous study. These findings imply that the saturation point of f44, and the use of f44 as an oxidation indicator, is case dependent.

  5. Summer Dust Aerosols Detected from CALIPSO Observations over the Tibetan Plateau

    NASA Technical Reports Server (NTRS)

    Huang, Jianping; Minnis, Patrick; Yi, Yuhong; Tang, Qiang; Wang, Xin; Hu, Yongxiang; Liu, Zhaoyan; Ayers, Kirk; Trepte, Charles; Winker, David

    2007-01-01

    Summertime Tibetan dust aerosol plumes are detected from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite. CALIPSO reveals that dust storms occur 4 times more frequently than previously found from Tibetan surface observations because few surface sites were available over remote northwestern Tibet. The Tibetan dust aerosol is characterized by column-averaged depolarization and color ratios around 21% and 0.83, respectively. The dust layers appear most frequently around 4-7 km above mean sea level. The depolarization ratio for about 90% of the dust particles is less than 10% at low altitudes (3-5 km), while only about 50% of the particles have a greater depolarization ratio at higher altitudes (7-10 km) suggesting a separation of larger irregular particles from smaller, near spherical ones during transport. The 4-day back trajectory analyses show that these plumes probably originate from the nearby Taklimakan desert surface and accumulate over the northern slopes of the Tibetan Plateau. These dust outbreaks can affect the radiation balance of the atmosphere of Tibet because they both absorb and reflect solar radiation.

  6. Joint retrieval of surface reflectance and aerosol properties from MSG/SEVIRI observations in the framework of aerosol_CCI2

    NASA Astrophysics Data System (ADS)

    Damman, Alix; Zunz, Violette; Govaerts, Yves; Kaminski, Thomas; Voßbeck, Michael

    2016-04-01

    The Meteosat satellites play an important role for the generation of consistent long time series of aerosol properties. This importance relies on (i) the long duration of past (Meteosat First Generation, MFG), present (Meteosat Second Generation, MSG) and future (Meteosat Third Generation, MTG) missions and (ii) their frequent cycle of acquisition that can be used to document the anisotropy of the surface and therefore the lower boundary condition for aerosol retrieval over land surfaces. The Package for the joint Inversion of Surface and Aerosol (PISA) is a new algorithm developed by Rayference and The Inversion Lab for the joint retrieval of surface reflectance and aerosol properties. It relies on the inversion of a physically-based radiative transfer model accounting for the surface reflectance anisotropy and its coupling with aerosol scattering. The inversion scheme accounts for prior knowledge on the surface properties and smoothness constraints on the temporal variation of aerosols. PISA also provides the posterior uncertainty covariance matrix for the retrieved variables in every processed pixel. The package has been applied on Top Of Atmosphere (TOA) Bidirectional Reflectance Factor (BRF) acquired by SEVIRI onboard Meteosat Second Generation (MSG) in the VIS0.6, VIS0.8 and NIR1.6 spectral bands. Observations are accumulated during a certain period of time to sufficiently document the surface anisotropy and minimize the impact of clouds. The surface radiative properties are retrieved for this entire accumulation period during which they are supposed to be constant. Aerosol properties however are derived on an hourly basis. Based on PISA, a processing chain has been developed and applied on 2008 MSG/SEVIRI observations for some specific sub-domains of the Earth disk. For these processed sub-domains, the information content of each MSG/SEVIRI band will be analysed based on the prior and posterior uncertainty covariance matrices. This constitutes a first step

  7. Optical constants of Titan aerosols and their tholins analogs: Experimental results and modeling/observational data

    NASA Astrophysics Data System (ADS)

    Brassé, Coralie; Muñoz, Olga; Coll, Patrice; Raulin, François

    2015-05-01

    Since Bishun Khare's pioneer works on Titan tholins, many studies have been performed to improve the experimental database of the optical constants of Titan tholins. The determination of the optical constants of Titan aerosols is indeed essential to quantify their capacity to absorb and scatter solar radiation, and thus to evaluate their role on Titan's radiative balance and climate. The study of the optical properties is also crucial to analyze and better interpret many of Titan's observational data, in particular those acquired during the Cassini-Huygens mission. This review paper critically summarizes these new results and presents constraints on Titan's aerosols optical constants. Finally, the information lacking in this field is highlighted as well as some possible investigations that could be carried out to fill these gaps.

  8. An Optimal-Estimation-Based Aerosol Retrieval Algorithm Using OMI Near-UV Observations

    NASA Technical Reports Server (NTRS)

    Jeong, U; Kim, J.; Ahn, C.; Torres, O.; Liu, X.; Bhartia, P. K.; Spurr, R. J. D.; Haffner, D.; Chance, K.; Holben, B. N.

    2016-01-01

    An optimal-estimation(OE)-based aerosol retrieval algorithm using the OMI (Ozone Monitoring Instrument) near-ultraviolet observation was developed in this study. The OE-based algorithm has the merit of providing useful estimates of errors simultaneously with the inversion products. Furthermore, instead of using the traditional lookup tables for inversion, it performs online radiative transfer calculations with the VLIDORT (linearized pseudo-spherical vector discrete ordinate radiative transfer code) to eliminate interpolation errors and improve stability. The measurements and inversion products of the Distributed Regional Aerosol Gridded Observation Network campaign in northeast Asia (DRAGON NE-Asia 2012) were used to validate the retrieved aerosol optical thickness (AOT) and single scattering albedo (SSA). The retrieved AOT and SSA at 388 nm have a correlation with the Aerosol Robotic Network (AERONET) products that is comparable to or better than the correlation with the operational product during the campaign. The OEbased estimated error represented the variance of actual biases of AOT at 388 nm between the retrieval and AERONET measurements better than the operational error estimates. The forward model parameter errors were analyzed separately for both AOT and SSA retrievals. The surface reflectance at 388 nm, the imaginary part of the refractive index at 354 nm, and the number fine-mode fraction (FMF) were found to be the most important parameters affecting the retrieval accuracy of AOT, while FMF was the most important parameter for the SSA retrieval. The additional information provided with the retrievals, including the estimated error and degrees of freedom, is expected to be valuable for relevant studies. Detailed advantages of using the OE method were described and discussed in this paper.

  9. An optimal-estimation-based aerosol retrieval algorithm using OMI near-UV observations

    NASA Astrophysics Data System (ADS)

    Jeong, U.; Kim, J.; Ahn, C.; Torres, O.; Liu, X.; Bhartia, P. K.; Spurr, R. J. D.; Haffner, D.; Chance, K.; Holben, B. N.

    2016-01-01

    An optimal-estimation(OE)-based aerosol retrieval algorithm using the OMI (Ozone Monitoring Instrument) near-ultraviolet observation was developed in this study. The OE-based algorithm has the merit of providing useful estimates of errors simultaneously with the inversion products. Furthermore, instead of using the traditional look-up tables for inversion, it performs online radiative transfer calculations with the VLIDORT (linearized pseudo-spherical vector discrete ordinate radiative transfer code) to eliminate interpolation errors and improve stability. The measurements and inversion products of the Distributed Regional Aerosol Gridded Observation Network campaign in northeast Asia (DRAGON NE-Asia 2012) were used to validate the retrieved aerosol optical thickness (AOT) and single scattering albedo (SSA). The retrieved AOT and SSA at 388 nm have a correlation with the Aerosol Robotic Network (AERONET) products that is comparable to or better than the correlation with the operational product during the campaign. The OE-based estimated error represented the variance of actual biases of AOT at 388 nm between the retrieval and AERONET measurements better than the operational error estimates. The forward model parameter errors were analyzed separately for both AOT and SSA retrievals. The surface reflectance at 388 nm, the imaginary part of the refractive index at 354 nm, and the number fine-mode fraction (FMF) were found to be the most important parameters affecting the retrieval accuracy of AOT, while FMF was the most important parameter for the SSA retrieval. The additional information provided with the retrievals, including the estimated error and degrees of freedom, is expected to be valuable for relevant studies. Detailed advantages of using the OE method were described and discussed in this paper.

  10. Increase of Cloud Droplet Size with Aerosol Optical Depth: An Observational and Modeling Study

    SciTech Connect

    Yuan, Tianle; Li, Zhanqing; Zhang, Renyi; Fan, Jiwen

    2008-02-21

    Cloud droplet effective radius (DER) is generally negatively correlated with aerosol optical depth (AOD) as a proxy of cloud condensation nuclei. In this study, cases of positive correlation were found over certain portions of the world by analyzing the Moderate Resolution Imaging Spectroradiometer (MODIS) satellite products, together with a general finding that DER may increase or decrease with aerosol loading depending on environmental conditions. The slope of the correlation between DER and AOD is driven primarily by water vapor amount, which explains 70% of the variance in our study. Various potential artifacts that may cause the positive relation are investigated including water vapor swelling, partially cloudy, atmospheric dynamics, cloud three-dimensional (3-D) and surface influence effects. None seems to be the primary cause for the observed phenomenon, although a certain degree of influence exists for some of the factors. Analyses are conducted over seven regions around the world representing different types of aerosols and clouds. Only two regions show positive dependence of DER on AOD, near coasts of the Gulf of Mexico and South China Sea, which implies physical processes may at work. Using a 2-D spectral-bin microphysics Goddard Cumulus Ensemble model (GCE) which incorporated a reformulation of the Köhler theory, two possible physical mechanisms are hypothesized. They are related to the effects of slightly soluble organics (SSO) particles and giant CCNs. Model simulations show a positive correlation between DER and AOD, due to a decrease in activated aerosols with an increasing SSO content. Addition of a few giant CCNs also increases the DER. Further investigations are needed to fully understand and clarify the observed phenomenon.

  11. Joint retrieval of hourly-resolved aerosol optical depths and surface reflectance using MSG/SEVIRI observations

    NASA Astrophysics Data System (ADS)

    Wagner, Sebastien; Govaerts, Yves

    2010-05-01

    A new aerosol algorithm is developed at EUMETSAT to derive simultaneously the surface bidirectional reflectance factor (BRF) and the hourly variations of the tropospheric aerosol load from observations acquired by the SEVIRI radiometer on-board the Meteosat Second Generation satellites. In order to retrieve the aerosol optical thickness for each cloud-free observation, the algorithm makes the assumption that both the aerosol class and the surface radiative properties do not change during the course of the day. Hence, this algorithm infers the surface BRF from a forward radiative transfer model against daily accumulated observations in the 0.6, 0.8 and 1.6 MSG/SEVIRI bands. These daily time series provide the angular sampling used to discriminate the radiative effects that result from the surface anisotropy, from those caused by the aerosol scattering. The inversion method relies on the Optimal Estimation method which balances the information derived from the observations and the prior knowledge on the system. This approach allows the tracking of sharp daily variations of the aerosol atmospheric load, in particular in the case of quickly developing dust storm fronts. Results of comparisons with the AERONET aerosol product are presented on specific cases on pixel basis in order to assess the performance of this new algorithm.

  12. An offline constrained data assimilation technique for aerosols: Improving GCM simulations over South Asia using observations from two satellite sensors

    NASA Astrophysics Data System (ADS)

    Baraskar, Ankit; Bhushan, Mani; Venkataraman, Chandra; Cherian, Ribu

    2016-05-01

    Aerosol properties simulated by general circulation models (GCMs) exhibit large uncertainties due to biases in model processes and inaccuracies in aerosol emission inputs. In this work, we propose an offline, constrained optimization based procedure to improve these simulations by assimilating them with observational data. The proposed approach explicitly incorporates the non-negativity constraint on the aerosol optical depth (AOD) which is a key metric to quantify aerosol distributions. The resulting optimization problem is quadratic programming in nature and can be easily solved by available optimization routines. The utility of the approach is demonstrated by performing offline assimilation of GCM simulated aerosol optical properties and radiative forcing over South Asia (40-120 E, 5-40 N), with satellite AOD measurements from two sensors, namely Moderate Resolution Imaging SpectroRadiometer (MODIS) and Multi-Angle Imaging SpectroRadiometer (MISR). Uncertainty in observational data used in the assimilation is computed by developing different error bands around regional AOD observations, based on their quality assurance flags. The assimilation, evaluated on monthly and daily scales, compares well with Aerosol Robotic Network (AERONET) observations as determined by goodness of fit statistics. Assimilation increased both model predicted atmospheric absorption and clear sky radiative forcing by factors consistent with recent estimates in literature. Thus, the constrained assimilation algorithm helps in systematically reducing uncertainties in aerosol simulations.

  13. Observations and analysis of organic aerosol evolution in some prescribed fire smoke plumes

    NASA Astrophysics Data System (ADS)

    May, A. A.; Lee, T.; McMeeking, G. R.; Akagi, S.; Sullivan, A. P.; Urbanski, S.; Yokelson, R. J.; Kreidenweis, S. M.

    2015-06-01

    Open biomass burning is a significant source of primary air pollutants such as particulate matter (PM) and non-methane organic gases (NMOG). However, the physical and chemical atmospheric processing of these emissions during transport is poorly understood. Atmospheric transformations of biomass burning emissions have been investigated in environmental chambers, but there have been limited opportunities to investigate these transformations in the atmosphere. In this study, we deployed a suite of real-time instrumentation on a Twin Otter aircraft to sample smoke from prescribed fires in South Carolina, conducting measurements at both the source and downwind to characterize smoke evolution with atmospheric aging. Organic aerosol (OA) within the smoke plumes was quantified using an aerosol mass spectrometer (AMS); refractory black carbon (rBC) was quantified using a single-particle soot photometer, and carbon monoxide (CO) and carbon dioxide (CO2) were measured using a cavity ring-down spectrometer. During the two fires for which we were able to obtain aerosol aging data, normalized excess mixing ratios and "export factors" of conserved species (rBC, CO, CO2) suggested that changes in emissions at the source did not account for most of the differences observed in samples of increasing age. An investigation of AMS mass fragments indicated that the in-plume fractional contribution (fm/z) to OA of the primary fragment (m/z 60) decreased downwind, while the fractional contribution of the secondary fragment (m/z 44) increased. Increases in f44 are typically interpreted as indicating chemical aging of OA. Likewise, we observed an increase in the O : C elemental ratio downwind, which is usually associated with aerosol aging. However, the rapid mixing of these plumes into the background air suggests that these chemical transformations may be attributable to the different volatilities of the compounds that fragment to these m/z in the AMS. The gas-particle partitioning behavior

  14. Extremely intense ELF magnetosonic waves: A survey of polar observations

    NASA Astrophysics Data System (ADS)

    Tsurutani, Bruce T.; Falkowski, Barbara J.; Pickett, Jolene S.; Verkhoglyadova, Olga P.; Santolik, Ondrej; Lakhina, Gurbax S.

    2014-02-01

    A Polar magnetosonic wave (MSW) study was conducted using 1 year of 1996-1997 data (during solar minimum). Waves at and inside the plasmasphere were detected at all local times with a slight preference for occurrence in the midnight-postmidnight sector. Wave occurrence (and intensities) peaked within~±5° of the magnetic equator, with half maxima at ~±10°. However, MSWs were also detected as far from the equator as +20° and 60° MLAT but with lower intensities. An extreme MSW intensity event of amplitude Bw = ~± 1 nT and Ew = ~± 25 mV/m was detected. This event occurred near local midnight, at the plasmapause, at the magnetic equator, during an intense substorm event, e.g., a perfect occurrence. These results support the idea of generation by protons injected from the plasma sheet into the midnight sector magnetosphere by substorm electric fields. MSWs were also detected near noon (1259 MLT) during relative geomagnetic quiet (low AE). A possible generation mechanism is a recovering/expanding plasmasphere engulfing preexisting energetic ions, in turn leading to ion instability. The wave magnetic field components are aligned along the ambient magnetic field direction, with the wave electric components orthogonal, indicating linear wave polarization. The MSW amplitudes decreased at locations further from the magnetic equator, while transverse whistler mode wave amplitudes (hiss) increased. We argue that intense MSWs are always present somewhere in the magnetosphere during strong substorm/convection events. We thus suggest that modelers use dynamic particle tracing codes and the maximum (rather than average) wave amplitudes to simulate wave-particle interactions.

  15. Long-Term Variation of Stratospheric Aerosols Observed With Lidar from 1982 to 2014 Over Tsukuba, Japan

    NASA Astrophysics Data System (ADS)

    Sakai, Tetsu; Uchino, Osamu; Nagai, Tomohiro; Fujimoto, Toshifumi; Tabata, Isao

    2016-06-01

    The vertical distribution of stratospheric aerosols has been measured with lidars at the Meteorological Research Institute (MRI) over Tsukuba since 1982. After two major volcanic eruptions (Mt. El Chichón in 1982 and Mt. Pinatubo in 1991), stratospheric aerosol loading increased about 50-100 times compared with the background level which was observed for 1997-2000. From 2000 to 2012, a slight increase (5.3% year-1) was observed by some volcanic eruptions. This long-term lidar data have been used for assessing of impact of the stratospheric aerosols on climate and the ozone layer.

  16. Characteristics of aerosols in urban and rural areas: GEOS-Chem+APM nested grid simulation and comparison with observations

    NASA Astrophysics Data System (ADS)

    Luo, G.; Yu, F.

    2011-12-01

    Aerosol microphysics (nucleation, condensation, growth and coagulation) shows significant impact on aerosol size distribution which is important for the investigation of aerosol properties and its associated environment and climate impacts. Here, we use a recently developed global size-resolved aerosol microphysics model (GEOS-Chem+APM, Yu and Luo, ACP, 2009), which uses the ion-mediated nucleation theory to simulate tropospheric particle formation and a new scheme to consider the kinetic condensation of low volatile secondary organic gas (SOG) (in addition to H2SO4 gas) on nucleated particles, to study the major characteristics of aerosol size distribution in urban and rural areas and explore the key factors dominating aerosol properties over these regions. Multiple-year simulations with a nested domain (horizontal resolution 0.5ox0.667o) over Europe have been carried out and compared with long-term continuous particle size distribution measurements at an urban area (Melpitz, Gernmay) and a rural area (Hyytiälä, Finland). The analysis shows that aerosol number concentration at the urban site is generally three times higher than that at the rural site. Significant diurnal and inter-monthly variations of aerosol nucleation events can be found at both sites. Because of high concentration of sulfur acid, freshly nucleated particles at urban site are much easier to grow to large-size particles rather than those at rural site. The model captures the major characteristics of aerosol size distribution observed at the two sites. Model simulation implicates that sulfur acid dominates particle growth process at Melpitz, while SOG shows significant contribution at Hyytiälä, especially during summertime. We also study the mixing state of aerosols at both the urban and rural sites, and aerosol optical property and radiative forcing in urban and rural areas are calculated to investigate the associated environment and climate impacts over these regions.

  17. 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

  18. Satellite observations and EMAC model calculations of sulfate aerosols from Kilauea: a study of aerosol formation, processing, and loss

    NASA Astrophysics Data System (ADS)

    Penning de Vries, Marloes; Beirle, Steffen; Brühl, Christoph; Dörner, Steffen; Pozzer, Andrea; Wagner, Thomas

    2016-04-01

    The currently most active volcano on Earth is Mount Kilauea on Hawaii, as it has been in a state of continuous eruption since 1983. The opening of a new vent in March 2008 caused half a year of strongly increased SO2 emissions, which in turn led to the formation of a sulfate plume with an extent of at least two thousand kilometers. The plume could be clearly identified from satellite measurements from March to November, 2008. The steady trade winds in the region and the lack of interfering sources allowed us to determine the life time of SO2 from Kilauea using only satellite-based measurements (no a priori or model information). The current investigation focuses on sulfate aerosols: their formation, processing and subsequent loss. Using space-based aerosol measurements by MODIS, we study the evolution of aerosol optical depth, which first increases as a function of distance from the volcano due to aerosol formation from SO2 oxidation, and subsequently decreases as aerosols are deposited to the surface. The outcome is compared to results from calculations using the EMAC (ECHAM/MESSy Atmospheric Chemistry) model to test the state of understanding of the sulfate aerosol life cycle. For this comparison, a particular focus is on the role of clouds and wet removal processes.

  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. Observations of the Interaction and/or Transport of Aerosols with Cloud or Fog during DRAGON Campaigns from AERONET Ground-Based Remote Sensing

    NASA Astrophysics Data System (ADS)

    Eck, Thomas; Holben, Brent; Schafer, Joel; Giles, David; Kim, Jhoon; Kim, Young; Sano, Itaru; Reid, Jeffrey; Pickering, Kenneth; Crawford, James; Sinyuk, Alexander; Trevino, Nathan

    2014-05-01

    Ground-based remote sensing observations from Aerosol Robotic Network (AERONET) sun-sky radiometers have recently shown several instances where cloud-aerosol interaction had resulted in modification of aerosol properties and/or in difficulty identifying some major pollution transport events due to aerosols being imbedded in cloud systems. AERONET has established Distributed Regional Aerosol Gridded Observation Networks (DRAGON) during field campaigns that are short-term (~2-3 months) relatively dense spatial networks of ~15 to 45 sun and sky scanning photometers. Recent major DRAGON field campaigns in Japan and South Korea (Spring 2012) and California (Winter 2013) have yielded observations of aerosol transport associated with clouds and/or aerosol properties modification as a result of fog interaction. Analysis of data from the Korean and Japan DRAGON campaigns shows that major fine-mode aerosol transport events are sometimes associated with extensive cloud cover and that cloud-screening of observations often filter out significant pollution aerosol transport events. The Spectral De-convolution Algorithm (SDA) algorithm was utilized to isolate and analyze the fine-mode aerosol optical depth signal for these cases of persistent and extensive cloud cover. Additionally, extensive fog that was coincident with aerosol layer height on some days in both Korea and California resulted in large increases in fine mode aerosol radius, with a mode of cloud-processed or residual aerosol of radius ~0.4-0.5 micron sometimes observed. Cloud processed aerosol may occur much more frequently than AERONET data suggest due to inherent difficulty in observing aerosol properties near clouds from remote sensing observations. These biases of aerosols associated with clouds would likely be even greater for satellite remote sensing retrievals of aerosol properties near clouds due to 3-D effects and sub-pixel cloud contamination issues.

  1. 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

  2. Multi-wavelength Airborne High Spectral Resolution Lidar Observations of Aerosol Above Clouds in California during DISCOVER-AQ

    NASA Astrophysics Data System (ADS)

    Hostetler, C. A.; Burton, S. P.; Ferrare, R. A.; Rogers, R. R.; Mueller, D.; Chemyakin, E.; Cook, A. L.; Harper, D. B.; Ziemba, L. D.; Beyersdorf, A. J.; Anderson, B. E.

    2013-12-01

    Accurately representing the vertical profile of aerosols is important for determining their radiative impact, which is still one of the biggest uncertainties in climate forcing. Aerosol radiative forcing can be either positive or negative depending on aerosol absorption properties and underlying albedo. Therefore, accurately characterizing the vertical distribution of aerosols, and specifically aerosols above clouds, is vital to understanding climate change. Unlike passive sensors, airborne lidar has the capability to make vertically resolved aerosol measurements of aerosols above and between clouds. Recently, NASA Langley Research Center has built and deployed the world's first airborne multi-wavelength High Spectral Resolution Lidar, HSRL-2. The HSRL-2 instrument employs the HSRL technique to measure extinction at both 355 nm and 532 nm and also measures aerosol depolarization and backscatter at 355 nm, 532 nm and 1064 nm. Additional HSRL-2 data products include aerosol type and range-resolved aerosol microphysical parameters (e.g., effective radius, number concentration, and single scattering albedo). HSRL-2 was deployed in the San Joaquin Valley, California, from January 16 to February 6, 2013, on the DISCOVER-AQ field campaign (Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality). On February 6, the observation region was mostly cloudy, and HSRL-2 saw two distinct aerosol layers above the clouds. One layer was aged boundary-layer pollution located just above cloud top at approximately 1.5 km above sea level. An aged smoke layer was also observed over land and over the ocean at altitudes 4-7 km ASL. In this study, we will show HSRL-2 products for these cases, and compare them with airborne in situ measurements of the 1.5-km layer from a coincident flight of the NASA P3B. We will also compare and contrast the HSRL-2 measurements of these two aerosol layers with each other and the clear-air boundary

  3. Aerosol, Cloud, and Climate: From Observation to Model (457th Brookhaven Lecture)

    ScienceCinema

    Wang, Jian [Ph.D., Environmental Sciences Department

    2010-09-01

    In the last 100 years, the Earth has warmed by about 1ºF, glaciers and sea ice have been melting more quickly than previously, especially during the past decade, and the level of the sea has risen about 6-8 inches worldwide. Scientists have long been investigating this phenomenon of ?global warming,? which is believed to be at least partly due to the increased carbon dioxide (CO2) concentration in the air from burning fossil fuels. Funded by DOE, teams of researchers from BNL and other national labs have been gathering data in the U.S. and internationally to build computer models of climate and weather to help in understanding general patterns, causes, and perhaps, solutions. Among many findings, researchers observed that atmospheric aerosols, minute particles in the atmosphere, can significantly affect global energy balance and climate. Directly, aerosols scatter and absorb sunlight. Indirectly, increased aerosol concentration can lead to smaller cloud droplets, changing clouds in ways that tend to cool global climate and potentially mask overall warming from man-made CO2.

  4. Observational evidence on the effects of clouds and aerosols on net ecosystem exchange and evapotranspiration

    NASA Astrophysics Data System (ADS)

    Wang, Kaicun; Dickinson, Robert E.; Liang, Shunlin

    2008-05-01

    Clouds and aerosols control variations in the ratio of diffuse to total incident solar radiation (R d /R s ) and so determine to a large extent variations in both Light-Use Efficiency (LUE) and in the Evaporative Fraction (EF). Five years (2002-2007) of continuous ground measurements collected at twenty-three sites in the U.S. were analyzed to quantify this effect. Our results show that LUE is 19.4% and 203% larger for patchy clouds, and thick clouds than those for clear skies while LUE is about -6% for aerosols or thin clouds than those for clear skies. EF is 15.4%, 17.9% and 23.2% larger for aerosols or thin clouds, patchy clouds, and thick clouds than those for the clear sky when Eddy Covariance (ECOR) data are used, respectively. The values are 9.0%, 11.3% and 23.3% when Energy Balance Bowen Ratio (EBBR) data are used. This is the first systematic observational study on effects of R d /R s on EF and further study is needed.

  5. Aerosol, Cloud, and Climate: From Observation to Model (457th Brookhaven Lecture)

    SciTech Connect

    Wang, Jian

    2010-05-12

    In the last 100 years, the Earth has warmed by about 1ºF, glaciers and sea ice have been melting more quickly than previously, especially during the past decade, and the level of the sea has risen about 6-8 inches worldwide. Scientists have long been investigating this phenomenon of “global warming,” which is believed to be at least partly due to the increased carbon dioxide (CO2) concentration in the air from burning fossil fuels. Funded by DOE, teams of researchers from BNL and other national labs have been gathering data in the U.S. and internationally to build computer models of climate and weather to help in understanding general patterns, causes, and perhaps, solutions. Among many findings, researchers observed that atmospheric aerosols, minute particles in the atmosphere, can significantly affect global energy balance and climate. Directly, aerosols scatter and absorb sunlight. Indirectly, increased aerosol concentration can lead to smaller cloud droplets, changing clouds in ways that tend to cool global climate and potentially mask overall warming from man-made CO2.

  6. Long-term Observation of Aerosol Optical Properties at the SORPES station in Nanjing, China

    NASA Astrophysics Data System (ADS)

    Shen, Yicheng; Ding, Aijun; Virkkula, Aki; Wang, Jiaping; Chi, Xuguang; Qi, Ximeng; Liu, Qiang; Zheng, Longfei; Xie, Yuning

    2016-04-01

    Atmospheric aerosols influence the earth's radiation budget by scattering and absorbing solar radiation and contribute substantial uncertainty in the estimation of climate forcing. Thorough and comprehensive measurements on different parameters including absorption and scattering coefficient, wavelength dependence and angular dependence along with their daily and seasonal variation help to understand the influence of aerosol on radiation. 2-years continuous measurement of aerosol optical properties has been conducted from June 2013 to May 2015 at the Station for Observing Regional Process of Earth System (SORPES) station, which is a regional background station located in downwind direction of Yangtze River Delta (YRD) urban agglomeration in China. A 7-wavelenths aethalometer and a 3-wavelenths nephelometer were used to measure absorption and scattering coefficient, and also other parameters like single scattering albedo (SSA), absorption angstrom Exponent (AAE), scattering angstrom exponent (SAE) and back-scattering refraction. In addtion, simultaneous measurements on chemical composition and particle size distribution were performed so as to investigate the dependencies of aerosol optical properties on chemical composition and size distribution. To get further insight on the influencing factors, Lagrangian particle dispersion modeling (LPDM) was employed for source identification in this study. The averages of absorption coefficient, scattering coefficient and SSA are 26.0±18.7 Mm-1, 426±327 Mm-1 , 0.936±0.3 at 520nm respectively for whole period. SAE between 450 and 635nm is 1.299±0.34 and have strong negative correlation with particle Surface Mean Diameter (SMD). AAE between 370 and 950nm is 1.043±0.15 for whole period but growth to more than 1.6 in all identified Biomass Burning (BB) events.

  7. Towards identification of relevant variables in the observed aerosol optical depth bias between MODIS and AERONET observations

    NASA Astrophysics Data System (ADS)

    Malakar, N. K.; Lary, D. J.; Gencaga, D.; Albayrak, A.; Wei, J.

    2013-08-01

    Measurements made by satellite remote sensing, Moderate Resolution Imaging Spectroradiometer (MODIS), and globally distributed Aerosol Robotic Network (AERONET) are compared. Comparison of the two datasets measurements for aerosol optical depth values show that there are biases between the two data products. In this paper, we present a general framework towards identifying relevant set of variables responsible for the observed bias. We present a general framework to identify the possible factors influencing the bias, which might be associated with the measurement conditions such as the solar and sensor zenith angles, the solar and sensor azimuth, scattering angles, and surface reflectivity at the various measured wavelengths, etc. Specifically, we performed analysis for remote sensing Aqua-Land data set, and used machine learning technique, neural network in this case, to perform multivariate regression between the ground-truth and the training data sets. Finally, we used mutual information between the observed and the predicted values as the measure of similarity to identify the most relevant set of variables. The search is brute force method as we have to consider all possible combinations. The computations involves a huge number crunching exercise, and we implemented it by writing a job-parallel program.

  8. UV intensity distributions of the quiet Sun observed with Sunrise

    NASA Astrophysics Data System (ADS)

    Hirzberger, Johann; Feller, A.; Riethmueller, T.; Borrero, J. M.; Schüssler, M.; Barthol, P.; Berkefeld, T.; Gandorfer, A.; Knoelker, M.; Martínez Pillet, V.; Schmidt, W.; Solanki, S.; Title, A.

    High resolution solar images in the near UV have been obtained with the Solar UV Filtergraph (SUFI) onboard the Sunrise balloon borne observatory, amongst others in wavelength regions not accessible from the ground. We present intensity distributions of the quiet Sun at different heliocentric angles, from disk center to the solar limb. These results, obtained in spectral windows at 214 nm, 313 nm (OH band), 388 nm (CN band) and 396.7 nm (CaIIH), represent an important validation of numerical models of the solar photosphere and are, thus, fundamental ingredients for our understanding of the thermal processes in the solar surface region.

  9. 3D Aerosol-Cloud Radiative Interaction Observed in Collocated MODIS and ASTER Images of Cumulus Cloud Fields

    NASA Technical Reports Server (NTRS)

    Wen, Guoyong; Marshak, Alexander; Cahalan, Robert F.; Remer, Lorraine A.; Kleidman, Richard G.

    2007-01-01

    3D aerosol-cloud interaction is examined by analyzing two images containing cumulus clouds in biomass burning regions in Brazil. The research consists of two parts. The first part focuses on identifying 3D clo ud impacts on the reflectance of pixel selected for the MODIS aerosol retrieval based purely on observations. The second part of the resea rch combines the observations with radiative transfer computations to identify key parameters in 3D aerosol-cloud interaction. We found that 3D cloud-induced enhancement depends on optical properties of nearb y clouds as well as wavelength. The enhancement is too large to be ig nored. Associated biased error in 1D aerosol optical thickness retrie val ranges from 50% to 140% depending on wavelength and optical prope rties of nearby clouds as well as aerosol optical thickness. We caution the community to be prudent when applying 1D approximations in comp uting solar radiation in dear regions adjacent to clouds or when usin g traditional retrieved aerosol optical thickness in aerosol indirect effect research.

  10. Proposal for observing intensity-intensity-correlation speckle patterns with thermal light via phase conjugation

    NASA Astrophysics Data System (ADS)

    Wang, Li-Gang; Al-Amri, M.; Zubairy, M. Suhail

    2015-10-01

    In traditional Hanbury Brown-Twiss (HBT) schemes, thermal intensity-intensity correlations (IICs) are phase insensitive. Here we propose a modified HBT scheme with phase conjugation to demonstrate phase-sensitive and nonfactorizable features of thermal IIC speckles. It shows that the novel phase-sensitive features originate from the correlation between the original and phase-conjugated thermal light. Our numerical simulation confirms the possibility of experimental realization, even for the cases of the imperfect phase conjugation. Unlike two-photon speckles, our scheme uses thermal light sources, not the entangled two-photon sources. Our result provides deeper insight into thermal correlations and may lead to significant applications in imaging and speckle technologies.

  11. Observationally-constrained carbonaceous aerosol source estimates for the Pearl River Delta area of China

    NASA Astrophysics Data System (ADS)

    Li, N.; Fu, T.-M.; Cao, J. J.; Zheng, J. Y.; He, Q. Y.; Long, X.; Zhao, Z. Z.; Cao, N. Y.; Fu, J. S.; Lam, Y. F.

    2015-11-01

    We simulated elemental carbon (EC) and organic carbon (OC) aerosols over the Pearl River Delta (PRD) area of China and compared the results to seasonal surface measurements, with the aim of quantifying carbonaceous aerosol sources from a "top-down" perspective. Our regional model was driven by current-best estimates of PRD EC (39.5 Gg C yr-1) and OC (32.8 Gg C yr-1) emissions and included updated secondary organic aerosol formation pathways. The simulated annual mean EC and OC concentrations were 4.0 and 7.7 μg C m-3, respectively, lower than the observed annual mean EC and OC concentrations (4.5 and 13.1 μg C m-3, respectively). We used multiple regression to match the simulated EC against seasonal mean observations. The resulting top-down estimate for EC emission in the PRD area was 52.9 ± 8.0 Gg C yr-1. We estimated the OC emission in the PRD area to be 60.2 ± 10.3 Gg C yr-1, based on the top-down EC emission estimate and the primary OC / EC ratios derived from bottom-up statistics. Using these top-down emission estimates, the simulated average annual mean EC and OC concentrations were improved to 4.4 and 9.5 μg C m-3, respectively, closer to the observations. Secondary sources accounted for 42 % of annual mean surface OC in our top-down simulations, with biogenic VOCs being the most important precursors.

  12. Optical properties and vertical distribution of pollution aerosols in the Mediterranean basin in summertime: airborne observations from the Charmex SOP0, SOP1, and SOP2 campaigns

    NASA Astrophysics Data System (ADS)

    Di Biagio, Claudia; Beekmann, Matthias; Chevallier, Servanne; Denjean, Cyrielle; Doppler, Lionel; Gaimoz, Cecile; Grand, Noel; Loisil, Rodrigue; Mallet, Marc; Pelon, Jacques; Ravetta, Francois; Sartelet, Karine; Schnitt, Sabrina; Triquet, Sylvain; Zapf, Pascal; Formenti, Paola

    2014-05-01

    The Mediterranean basin is a very complex area where high concentrations of atmospheric aerosols of different origin and types may be found. The North-Western part of the Mediterranean basin, due to its closeness with high polluted industrialized areas and coastal high populated cities, is frequently affected by severe pollution episodes. The strength of these episodes is particularly intense during summer when stable meteorological conditions favour the accumulation of pollutants in the lowermost atmospheric layers. Three intensive airborne campaigns (TRAQA, TRansport and Air QuAlity, June-July 2012), ADRIMED (Aerosol Direct Radiative Impact on the regional climate in the MEDiterranean region, June 2013) and SAFMED (Secondary Aerosol Formation in the MEDiterranean, July 2013) have been conducted over the North-Western and Central Mediterranean basin with the SAFIRE ATR-42 aircraft in the framework of the ChArMex Special Observing Periods 0 and 1. During the different campaigns the ATR-42 was equipped with a large set of instruments for the measurements of the aerosol physico-chemical (GRIMM, SMPS, PCASP, USHAS, FSSP for size distribution, and three lines for filter sampling on polycarbonate and quartz membranes in order to derive the bulk aerosol composition) and optical properties (TSI nephelometer, Magee Sci. aethalomether, and CAPS for scattering, absorption, and extinction coefficients at several wavelengths in the visible). Lidar backscatter profiles at 355, 532, and 1064 nm, meteorological parameters, upward and downward shortwave and longwave radiative fluxes, and atmospheric composition (H2O, CO2, CO, and O3) were also measured from aircraft instrumentation. In this work we present data on the aerosol physico-chemical and optical properties obtained during the 25 scientific flights of TRAQA, ADRIMED, and SAFMED performed in correspondence of pollution episodes. During the campaigns the Western Mediterranean basin was interested by different synoptic

  13. Model Evaluation of Aerosol Wet Scavenging in Deep Convective Clouds Based on Observations Collected during the DC3 Campaign

    NASA Astrophysics Data System (ADS)

    Yang, Q.; Easter, R. C.; Fast, J. D.; Wang, H.; Ghan, S. J.; Campuzano Jost, P.; Barth, M. C.; Fan, J.; Morrison, H.; Jimenez, J. L.; Bela, M. M.; Markovic, M. Z.

    2014-12-01

    Deep convective storms greatly influence the vertical distribution of aerosols by transporting aerosols from the boundary layer to the upper troposphere and by removing aerosols through wet scavenging processes. Model representation of wet scavenging is a major uncertainty in simulating the vertical distribution of aerosols due partly to limited constraints by observations. The effect of wet scavenging on ambient aerosols in deep mid-latitude continental convective clouds is studied for a severe storm case in the vicinity of the ARM Southern Great Plains site on May 29, 2012 during the Deep Convective Clouds and Chemistry Project (DC3) field campaign. A new budget analysis approach is developed to characterize the convective transport to the upper troposphere based on the vertical distribution of several slowly reacting and nearly insoluble trace gases (i.e., CO, acetone, and benzene). A similar budget framework is applied to aerosols combined with the known transport efficiency to estimate wet-scavenging efficiency. The chemistry version of the Weather Research and Forecasting model (WRF-Chem) simulates the storm initiation timing and structure reasonably well when compared against radar observations from the NSSL national 3-D reflectivity Mosaic data. Simulated vertical profiles of humidity and temperature also closely agree with radiosonde measurements before and during the storm. High scavenging efficiencies (~80%) for aerosol number (Dp < 2.5μm) and mass (Dp < 1μm) are obtained from the observations. Both observation analyses and the simulation show that, between the two dominant aerosol species, organic aerosol shows a slightly higher scavenging efficiency than sulfate aerosol, and higher scavenging efficiency is found for larger particle sizes (0.15 - 2.5μm versus 0.03 - 0.15μm). However, the model underestimates the wet scavenging efficiency (by up to 50%), in general, for both mass and number concentrations. The effect of neglecting secondary

  14. Transmission of 10 micron radiation over coastal waters: comparison of point-source image intensities with aerosol extinction and MODTRAN calculations

    NASA Astrophysics Data System (ADS)

    Schwering, Piet B.; de Leeuw, Gerrit; van Eijk, Alexander M.

    1996-10-01

    During the MAPTIP experiments in the Dutch coastal waters, 11 October - 5 November 1993, transmission curves were determined from the intensities of the image of a point source suspended from a helicopter at ranges between 0.5 and 6 NMi. The images were recorded with a 10 micrometer USFA 9092 camera from the MeetPost Noordwijk, a research tower in the North Sea at 9 km from the Dutch coast. The transmission determined from the point source intensities at several ranges is compared with calculated values. The transmission is determined by extinction due to aerosols and molecular species in the propagation path. Both contributions can be determined using code using measured size distributions. Also effects of path radiance and background on the image intensity are considered. In this coastal area, and the off- shore winds that were usually encountered during MAPTIP, the aerosol size distributions are known to be a complicated mixture of continental and marine aerosols. Hence the common aerosol models, that usually work well over the open ocean, are often not so reliable in a coastal environment. An attempt is made to assess the influence of marine and anthropogenic contributions to the aerosol on the detection range of point targets in a coastal atmosphere.

  15. The development and assessment of a flexible inversion algorithm for aerosol property retrieval combining passive multiangle multispectral intensity and polarization measurements

    NASA Astrophysics Data System (ADS)

    Tsekeri, Alexandra; Gross, Barry; Moshary, Fred; Ahmed, Samir

    2009-08-01

    Quantifying aerosols on a global scale is extremely important due to their strong but anomalous impact on the global climate. Traditionally, the aerosols retrievals use only the intensity measurements of the scattered light. However, these measurements are less sensitive to aerosol type and also suffer contamination from ground surfaces. It is with these limitations in mind that we plan to improve the quality and scope of aerosol retrieval by making use of soon to be available polarimetric sensors such as the Aerosol Polarimetry Sensor (APS) on the GLORY satellite and combine them with other available datasets such as lidar data from the CALIPSO satellite for vertical profiling, and high-spatialcoverage intensity measurements from MODIS. To handle these extremely large sensor data sets, we will explore the capabilities of various statistical methods and even combine them to create inversion algorithms that will work best. Up to now, we worked with the simplest case, the single-scattering approximation and built a retrieval algorithm using multi-angular, multi-wavelength simulated measurements of intensity and polarization. The inversion techniques we used are the optimal estimator and the neural networks.

  16. Path-analysis based validation of aerosol-precipitation micro-scale interaction using observational evidences

    NASA Astrophysics Data System (ADS)

    Dave, Prashant; Bhushan, Mani; Venkataraman, Chandra

    2016-04-01

    Aerosols can modulate variability of Indian summer monsoon by perturbing the radiative balance of the atmosphere, affecting the land-ocean processes and altering the cloud-microphysics at varying spatio-temporal scale, ranging from fast (less than a day) to slow (months) temporal effects. In the literature, overall interaction between AOD and Precipitation was quantified as correlation coefficients (Ramchandran and Kedia, 2013; Gryspeerdt et al., 2012; Gryspeerdt et al., 2014), however the segregation of the interaction was required to better understand the presence/absence of pathway mediated through changes in cloud-microphysics and atmospheric stability. In this work, effects of aerosols on precipitation, mediated through changes in cloud-microphysics and atmospheric stability, on daily time-scales, are studied and quantified using coincident observational data of aerosols, clouds and rainfall, using Path-analysis (Wright, 1969). MODIS, ERA-interim and IMD data-sets for years 2000-2009 for Aerosol optical depth (AOD), Column water vapour (CWV), Cloud droplet effective radius (CDERL), Convective available potential energy (CAPE) and Precipitation, over Indian region were used for the analysis. Cause-effect model was built to validate and quantify the effects of AOD on precipitation, mediated through CDERL and CAPE. To contrast cause-effect mechanism in presence and absence of aerosol fields, high AOD-low Precipitation and low AOD-low Precipitation clusters were formed. Cluster-averaged time series were used to calculate the lagged correlation (AOD leading) and provided as input to Path-analysis. "AOD-CDERL-Precipitation" and "AOD-CAPE-Precipitation" pathways were found to be statistically significant for high AOD-low Precipitation clusters while both were absent for low AOD-low Precipitation clusters, for years 2003 and 2004. For other years statistically significant pathway between AOD and Precipitation could not be found. In "AOD-CDERL-Precipitation" pathway

  17. Horizontal variability of aerosol optical properties observed during the ARCTAS airborne experiment

    NASA Astrophysics Data System (ADS)

    Shinozuka, Y.; Redemann, J.; Russell, P. B.; Livingston, J. M.; Clarke, A. D.; Podolske, J. R.

    2010-12-01

    The properties of tropospheric aerosol and gas vary within a satellite grid cell and between ground-based instruments. This hinders comparison between satellite and suborbital measurements of different spatial scales as well as their applications to climate and air quality studies. This paper quantifies the realistic range of the variability in aerosol optical depth (AOD), its Angstrom exponent, in-situ extinction coefficient and carbon monoxide mixing ratio over horizontal distances of 1-30 km, using measurements from the ARCTAS airborne experiment. The Canada phase in June and July 2008, in which smoke from local forest fires was sampled, likely represents the most heterogeneous of the ambient aerosol environments common over the globe. The relative standard deviation (stdrel) of AOD measured with the 14-channel Ames Airborne Tracking Sunphotometer (AATS-14) has median 19.4% (at 499 nm) among thousands of horizontal 20 km segments. For 6 km segments the analogous median is 9.1%. Another measure of horizontal variability, the autocorrelation (r) of AOD499 across 20 km and 6 km segments is 0.37 and 0.71, respectively. In contrast, the Alaska phase in April 2008, which sampled particles transported from Asia, is presumably among the most homogeneous environments. The median stdrel is 3.0% and r is 0.90, both over 30 km, only slightly different from those for 1 km (stdrel=0.4% and r=1.00). r in the Canada phase is ~0.2 less for in situ extinction coefficient (from a nephelometer and a particle soot absorption photometer) than for the AOD. It is ~0.1 less than for the carbon monoxide mixing ratio. The trends of horizontal variability with distance and aerosol environment are different for the wavelength dependence and the humidity response of light scattering. We discuss challenges in estimating aerosol optical properties, particle size and chemical composition from measurements at a distant location. The statistical parameters thus help interpret existing remote

  18. Urban light pollution - The effect of atmospheric aerosols on astronomical observations at night

    NASA Technical Reports Server (NTRS)

    Joseph, Joachim H.; Mekler, Yuri; Kaufman, Yoram J.

    1991-01-01

    The transfer of diffuse city light from a localized source through a dust-laden atmosphere with optical depth less than 0.5 has been analyzed in the source-observer plane on the basis of an approximate treatment. The effect on several types of astronomical observation at night has been studied, considering different size distributions and amounts as well as particle shapes of the aerosols. The analysis is made in terms of the signal-to-noise ratios for a given amount of aerosol. The model is applied to conditions at the Wise Astronomical Observatory in the Negev desert, and limiting backgrounds for spectroscopy, photometry, and photography of stars and extended objects have been calculated for a variety of signal-to-noise ratios. Applications to observations with different equipment at various distances from an urban area of any size are possible. Due to the use of signal-to-noise ratios, the conclusions are different for the different experimental techniques used in astronomy.

  19. A Survey of Airborne Observations of Biological Aerosol over the Continental United States during NASA SEAC4RS

    NASA Astrophysics Data System (ADS)

    Ziemba, L. D.; Venkateswaran, K.; Froyd, K.; Dibb, J. E.; Beyersdorf, A. J.; Chen, G.; Crumeyrolle, S.; Hudgins, C.; Lin, J. J.; Moore, R.; Thornhill, K. L.; Winstead, E.; Anderson, B. E.

    2013-12-01

    Aerosols play a significant role in regulating Earth's climate. Biological aerosols exist in the atmosphere in many forms including bacteria, fungal spores, pollens, viruses, and plant detritus. While laboratory studies have illustrated the potential for biological aerosol to act as efficient ice nuclei, ambient observations do not clearly show the significance of this mechanism for ice formation. Particularly lacking for assessing the role of biological aerosol on cloud processes are observations of the vertical extent of biological aerosol, especially in conjunction with strong convection as a pathway for redistributing particles from surface sources to the free troposphere. An extensive suite of instrumentation measuring aerosol chemical, physical, and optical properties was deployed aboard the NASA DC-8 aircraft during the SEAC4RS campaign (Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys) in August/September of 2013. Flights were focused on characterizing emissions and transport of aerosols in the Southeast United States, a region characterized by strong biogenic activity. Additionally, convection associated with the North American Monsoon and Atlantic-basin hurricanes was targeted. Airborne biological aerosol was specifically measured during SEAC4RS with a Wideband Integrated Bioaerosol Sensor (WIBS-4A, Droplet Measurement Technologies). WIBS-4A utilizes a single-particle laser-induced fluorescence technique at two excitation wavelengths (280nm and 370nm) to identify biological aerosol, in addition to simultaneous determination of optical size and asymmetry factor for particles with diameter greater than 800nm. Single-particle mass spectrometry coupled with filter-based chemical composition and bacterial speciation analyses will be used to assess relationships with co-emitted mineral dusts. Vertical profiles for the background atmosphere will be compared to profiles influenced by convective storms to assess

  20. Observations of fluorescent aerosol-cloud interactions in the free troposphere at the High-Altitude Research Station Jungfraujoch

    NASA Astrophysics Data System (ADS)

    Crawford, I.; Lloyd, G.; Herrmann, E.; Hoyle, C. R.; Bower, K. N.; Connolly, P. J.; Flynn, M. J.; Kaye, P. H.; Choularton, T. W.; Gallagher, M. W.

    2016-02-01

    The fluorescent nature of aerosol at a high-altitude Alpine site was studied using a wide-band integrated bioaerosol (WIBS-4) single particle multi-channel ultraviolet - light-induced fluorescence (UV-LIF) spectrometer. This was supported by comprehensive cloud microphysics and meteorological measurements with the aims of cataloguing concentrations of bio-fluorescent aerosols at this high-altitude site and also investigating possible influences of UV-fluorescent particle types on cloud-aerosol processes. Analysis of background free tropospheric air masses, using a total aerosol inlet, showed there to be a minor increase in the fluorescent aerosol fraction during in-cloud cases compared to out-of-cloud cases. The size dependence of the fluorescent aerosol fraction showed the larger aerosol to be more likely to be fluorescent with 80 % of 10 μm particles being fluorescent. Whilst the fluorescent particles were in the minority (NFl/NAll = 0.27 ± 0.19), a new hierarchical agglomerative cluster analysis approach, Crawford et al. (2015) revealed the majority of the fluorescent aerosols were likely to be representative of fluorescent mineral dust. A minor episodic contribution from a cluster likely to be representative of primary biological aerosol particles (PBAP) was also observed with a wintertime baseline concentration of 0.1 ± 0.4 L-1. Given the low concentration of this cluster and the typically low ice-active fraction of studied PBAP (e.g. pseudomonas syringae), we suggest that the contribution to the observed ice crystal concentration at this location is not significant during the wintertime.

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

    NASA Technical Reports Server (NTRS)

    Winker, David M.

    1999-01-01

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

  2. Observations of fluorescent aerosol-cloud interactions in the free troposphere at the Sphinx high Alpine research station, Jungfraujoch

    NASA Astrophysics Data System (ADS)

    Crawford, I.; Lloyd, G.; Bower, K. N.; Connolly, P. J.; Flynn, M. J.; Kaye, P. H.; Choularton, T. W.; Gallagher, M. W.

    2015-09-01

    The fluorescent nature of aerosol at a high Alpine site was studied using a wide-band integrated bioaerosol (WIBS-4) single particle multi-channel ultra violet-light induced fluorescence (UV-LIF) spectrometer. This was supported by comprehensive cloud microphysics and meteorological measurements with the aims of cataloguing concentrations of bio-fluorescent aerosols at this high altitude site and also investigating possible influences of UV-fluorescent particle types on cloud-aerosol processes. Analysis of background free tropospheric air masses, using a total aerosol inlet, showed there to be a minor but statistically insignificant increase in the fluorescent aerosol fraction during in-cloud cases compared to out of cloud cases. The size dependence of the fluorescent aerosol fraction showed the larger aerosol to be more likely to be fluorescent with 80 % of 10 μm particles being fluorescent. Whilst the fluorescent particles were in the minority (NFl/NAll = 0.27±0.19), a new hierarchical agglomerative cluster analysis approach, Crawford et al. (2015) revealed the majority of the fluorescent aerosol were likely to be representative of fluorescent mineral dust. A minor episodic contribution from a cluster likely to be representative of primary biological aerosol particles (PBAP) was also observed with a wintertime baseline concentration of 0.1±0.4 L-1. Given the low concentration of this cluster and the typically low ice active fraction of studied PBAP (e.g. pseudomonas syringae) we suggest that the contribution to the observed ice crystal concentration at this location is not significant during the wintertime.

  3. Carbonaceous aerosol and its characteristics observed in Tokyo and south Kanto region

    NASA Astrophysics Data System (ADS)

    Minoura, Hiroaki; Morikawa, Tazuko; Mizohata, Akira; Sakamoto, Kazuhiko

    2012-12-01

    Due to enforcing vehicle emission reduction requirements in Japan, particulate matter (PM) concentration, especially elemental carbon (EC) concentration in roadside atmosphere, obviously decreased in the last decade. In spite of the previous vehicle emission reduction, EC concentration was not shown a clear decrease, recently. To achieve the PM2.5 environmental standard, measurements based on emission source contribution are desirable. However, source apportionment of carbonaceous aerosol was ambiguous because chemical components are complicated, and the components change through photochemical reaction. The goal of this study is to determine source apportionment for carbonaceous aerosols. Examination of PM2.5 was performed in south Kanto including Tokyo in the summer of 2008 and the winter of 2009. Emissions from the industrial area around Tokyo Bay and the agricultural northern area showed transportation and accumulation due to the seasonal prevailing wind. The emissions formed a geographical distribution due to photochemical reactions. The characteristics of carbonaceous aerosol were obtained using carbon profile analysis and carbon isotope analysis, including the source information such as fossil fuel emission origin, vegetation origin, and combustion product, photochemical reaction product, etc. Soot-EC was found as a substance with fossil fuel origin which did not contain biomass combustion matter, and since it is stable, there was no observed difference by site and a uniform concentration was observed in winter. It became apparent from the carbon isotope analysis using 14C that the carbon from the biomass origin involved 29% in total carbon in the summer, and 48% in winter even at Kudan of central Tokyo.

  4. On recent (2008-2012) stratospheric aerosols observed by lidar over Japan

    NASA Astrophysics Data System (ADS)

    Uchino, O.; Sakai, T.; Nagai, T.; Nakamae, K.; Morino, I.; Arai, K.; Okumura, H.; Takubo, S.; Kawasaki, T.; Mano, Y.; Matsunaga, T.; Yokota, T.

    2012-12-01

    An increase in stratospheric aerosols caused by the volcanic eruption of Mt. Nabro (13.37° N, 41.70° E) on 12 June 2011 was detected by lidar at Tsukuba (36.05° N, 140.13° E) and Saga (33.24° N, 130.29° E) in Japan. The maximum backscattering ratios at a wavelength of 532 nm were 2.0 at 17.0 km on 10 July 2011 at Tsukuba and 3.6 at 18.2 km on 23 June 2011 at Saga. The maximum integrated backscattering coefficients (IBCs) at 532 nm above the first tropopause height were 4.18×10-4 sr-1 on 11 February 2012 at Tsukuba and 4.19×10-4 sr-1 on 23 June 2011 at Saga, respectively. A time series of lidar observational results at Tsukuba have also been reported from January 2008 through May 2012. Increases in stratospheric aerosols were observed after the volcanic eruptions of Mt. Kasatochi (52.18° N, 175.51° E) in August 2008 and Mt. Sarychev Peak (48.09° N, 153.20° E) in June 2009. The yearly averaged IBCs at Tsukuba were 2.54×10-4 sr-1, 2.48×10-4 sr-1, 2.45×10-4 sr-1, and 2.20×10-4 sr-1 for 2008, 2009, 2010, and 2011, respectively. These values were about twice the IBC background level (1.21×10-4 sr-1) from 1997 to 2001 at Tsukuba. We briefly discuss the influence of the increased aerosols on climate and the implications for analysis of satellite data.

  5. On recent (2008-2012) stratospheric aerosols observed by lidar over Japan

    NASA Astrophysics Data System (ADS)

    Uchino, O.; Sakai, T.; Nagai, T.; Nakamae, K.; Morino, I.; Arai, K.; Okumura, H.; Takubo, S.; Kawasaki, T.; Mano, Y.; Matsunaga, T.; Yokota, T.

    2012-09-01

    An increase in stratospheric aerosols caused by the volcanic eruption of Mt. Nabro (13.37° N, 41.70° E) on 12 June 2011 was first detected by lidar at Tsukuba (36.05° N, 140.13° E) and Saga (33.24° N, 130.29° E) in Japan. The maximum backscattering ratios at a wavelength of 532 nm were 2.0 at 17.0 km on 10 July 2011 at Tsukuba and 3.6 at 18.2 km on 23 June 2011 at Saga. The maximum integrated backscattering coefficients (IBCs) above the first tropopause height were 4.18 × 10-4 sr-1 on 11 February 2012 at Tsukuba and 4.19 × 10-4 sr-1 on 23 June 2011 at Saga, respectively. A time series of lidar observational results at Tsukuba have also been reported from January 2008 through May 2012. Increases in stratospheric aerosols were observed after the volcanic eruptions of Mt. Kasatochi (52.18° N, 175.51° E) in August 2008 and Mt. Sarychev Peak (48.09° N, 153.20° E) in June 2009. The yearly averaged IBCs at Tsukuba were 2.60 × 10-4 sr-1, 2.52 × 10-4 sr-1, 2.45 × 10-4 sr-1, and 2.20 × 10-4 sr-1 for 2008, 2009, 2010, and 2011, respectively. These values were about twice the IBC background level (1.21 × 10-4 sr-1) from 1997 to 2001 at Tsukuba. We briefly discuss the influence of the increased aerosols on climate and the implications for analysis of satellite data.

  6. Observations and analysis of organic aerosol evolution in some prescribed fire smoke plumes

    NASA Astrophysics Data System (ADS)

    May, A. A.; Lee, T.; McMeeking, G. R.; Akagi, S.; Sullivan, A. P.; Urbanski, S.; Yokelson, R. J.; Kreidenweis, S. M.

    2015-01-01

    Open biomass burning is a significant source of primary air pollutants such as particulate matter and non-methane organic gases. However, the physical and chemical atmospheric processing of these emissions during transport is poorly understood. Atmospheric transformations of biomass burning emissions have been investigated in environmental chambers, but there have been limited opportunities to investigate these transformations in the atmosphere. In this study, we deployed a suite of real-time instrumentation on a Twin Otter aircraft to sample smoke from prescribed fires in South Carolina, conducting measurements at both the source and downwind to characterize smoke evolution with atmospheric aging. Organic aerosol (OA) within the smoke plumes was quantified using an Aerosol Mass Spectrometer (AMS), along with refractory black carbon (rBC) using a Single Particle Soot Photometer and carbon monoxide (CO) and carbon dioxide (CO2) using a Cavity Ring-Down Spectrometer. During the two fires for which we were able to obtain aerosol aging data, normalized excess mixing ratios and "export factors" of conserved species (rBC, CO, CO2) were unchanged with increasing sample age. Investigation of AMS mass fragments indicated that the in-plume fractional contribution (fm/z) to OA of the primary fragment (m/z 60) decreased downwind, while the fractional contribution of the secondary fragment (m/z 44) increased. Increases in f44 are typically interpreted as indicating chemical production of secondary OA (SOA). Likewise, we observed an increase in the O : C elemental ratio downwind, which is usually associated with aerosol aging. However, the rapid mixing of these plumes into the background air suggests that these chemical transformations may be attributable to the different volatilities of the compounds that fragment to these m/z in the AMS. The gas-particle partitioning behavior of the bulk OA observed during the study was consistent with the predictions from a parameterization

  7. The detailed aerosol properties derived using GRASP Algorithm from multi-angular polarimetric POLDER/PARASOL observations

    NASA Astrophysics Data System (ADS)

    Dubovik, Oleg; Litvinov, Pavel; Lapyonok, Tatyana; Ducos, Fabrice; Fuertes, David; Huang, Xin; Derimian, Yevgeny; Ovigneur, Bertrand; Descloitres, Jacques

    2015-04-01

    The presentation introduces a new aerosol product derived from multi-angular polarimetric POLDER/PARASOL observations using recently developed GRASP algorithm The GRASP (Generalized Retrieval of Aerosol and Surface Properties) algorithm described by Dubovik et al. (2011, 2014) derives an extended set of aerosol parameters including detailed particle size distribution, spectral refractive index, single scattering albedo and the fraction of non-spherical particles. Over land GRASP simultaneously retrieves properties of both aerosol and underlying surface. The robust performance of algorithm was illustrated in a series of numerical tests and real data case studies. However, the algorithm is significantly slower than conventional look-up-table retrievals because it performs all radiative transfer calculations on-line. This is why the application of the algorithm for processing large volumes of satellite data was considered as unacceptably challenging task. During two last years GRASP algorithm and its operational retrieval environment has been significantly optimized, improved and adapted for processing extended set of observational data. Hence, here we demonstrate the first results of GRASP aerosol products obtained from large data sets of PARASOL/POLDER observations. It should be noted that in addition the core retrieved aerosol and surface parameters GRASP output may include a variety of user-oriented products including values of daily fluxes and aerosol radiative forcing. 1. Dubovik, O., M. Herman, A. Holdak, T. Lapyonok, D. Tanré, J. L. Deuzé, F. Ducos, A. Sinyuk, and A. Lopatin, "Statistically optimized inversion algorithm for enhanced retrieval of aerosol properties from spectral multi-angle polarimetric satellite observations", Atmos. Meas. Tech., 4, 975-1018, 2011. 2. Dubovik, O., T. Lapyonok, P. Litvinov, M. Herman, D. Fuertes, F. Ducos, A. Lopatin, A. Chaikovsky, B. Torres, Y. Derimian, X. Huang, M. Aspetsberger, and C. Federspiel "GRASP: a versatile

  8. Calculation of Intensity Ratios of Observed Infrared [Fe II] Lines

    NASA Astrophysics Data System (ADS)

    Deb, Narayan C.; Hibbert, Alan

    2010-03-01

    Two recent observational studies of the [Fe II] λ12567/λ16435 line ratio by Smith & Hartigan and Rodriguez-Ardila et al. have suggested that the available theoretical A-values could be incorrect to 10%-40%. We have carried out an extensive configuration interaction calculation of [Fe II] lines to investigate this claim, as well as the variability in observed line ratios for λ8617/λ9052 and λ8892/λ9227 of Dennefeld. For these transitions, we are generally in good agreement with the results of Nussbaumer & Storey, less so with those of Quinet et al. In comparison, the ratios derived from observations appear either to be less secure, or other factors influence those results.

  9. Multi-peak accumulation and coarse modes observed from AERONET retrieved aerosol volume size distribution in Beijing

    NASA Astrophysics Data System (ADS)

    Zhang, Ying; Li, Zhengqiang; Zhang, Yuhuan; Chen, Yu; Cuesta, Juan; Ma, Yan

    2016-01-01

    We present characteristic peaks of atmospheric columnar aerosol volume size distribution retrieved from the AErosol RObotic NETwork (AERONET) ground-based Sun-sky radiometer observation, and their correlations with aerosol optical properties and meteorological conditions in Beijing over 2013. The results show that the aerosol volume particle size distribution (VPSD) can be decomposed into up to four characteristic peaks, located in accumulation and coarse modes, respectively. The mean center radii of extra peaks in accumulation and coarse modes locate around 0.28 (±0.09) to 0.38 (±0.11) and 1.25 (±0.56) to 1.47 (±0.30) μm, respectively. The multi-peak size distributions are found in different aerosol loading conditions, with the mean aerosol optical depth (440 nm) of 0.58, 0.49, 1.18 and 1.04 for 2-, 3-I/II and 4-peak VPSD types, while the correspondingly mean relative humidity values are 58, 54, 72 and 67 %, respectively. The results also show the significant increase (from 0.25 to 0.40 μm) of the mean extra peak median radius in the accumulation mode for the 3-peak-II cases, which agrees with aerosol hygroscopic growth related to relative humidity and/or cloud or fog processing.

  10. The Lampedusa supersite of ChArMex: observing aerosol-radiation interactions and gas phase chemistry in the Mediterranean

    NASA Astrophysics Data System (ADS)

    Formenti, Paola; di Sarra, Alcide Giorgio

    2014-05-01

    Within the frame of the ADRIMED (Aerosol Direct Radiative Impact in the regional climate in the MEDiterranean region) project of the Chemistry-Aerosol Mediterranean experiment (ChArMex), the ENEA Laboratory for Climate Study "Roberto Sarao" (WMO/GAW/NDACC) on the Island of Lampedusa (35°31'N, 12°37°E) has been augmented to one of the supersites of the first phase of the Special Observing Period 1 by the measurements of the in situ properties of aerosols and trace gases by the of the PortablE Gas and Aerosol Sampling Units (PEGASUS) mobile station. The ground-based measurements have been completed by several coordinated overpasses of the ATR-42 and the F20 of SAFIRE. In this paper we present the first highlights of operations, which took place between June 6 and July 8 2013. Insights on the data provide with an unprecedented characterisation of the physico-chemical and properties aerosols and gas phase chemistry on air masses of various origins (pollution, marine, mineral dust, …..). The effect of aerosols on radiation fields is ascertained by coupling ground-based and aircraft measurements during dedicated overpasses providing with measurements of upwelling and downwelling shortwave and longwave radiation fluxes together with the properties of the aerosol load resolved on the column. Coordination with CALIPSO overpasses will also be explored.

  11. Multi-peak accumulation and coarse modes observed from AERONET retrieved aerosol volume size distribution in Beijing

    NASA Astrophysics Data System (ADS)

    Zhang, Ying; Li, Zhengqiang; Zhang, Yuhuan; Chen, Yu; Cuesta, Juan; Ma, Yan

    2016-08-01

    We present characteristic peaks of atmospheric columnar aerosol volume size distribution retrieved from the AErosol RObotic NETwork (AERONET) ground-based Sun-sky radiometer observation, and their correlations with aerosol optical properties and meteorological conditions in Beijing over 2013. The results show that the aerosol volume particle size distribution (VPSD) can be decomposed into up to four characteristic peaks, located in accumulation and coarse modes, respectively. The mean center radii of extra peaks in accumulation and coarse modes locate around 0.28 (±0.09) to 0.38 (±0.11) and 1.25 (±0.56) to 1.47 (±0.30) μm, respectively. The multi-peak size distributions are found in different aerosol loading conditions, with the mean aerosol optical depth (440 nm) of 0.58, 0.49, 1.18 and 1.04 for 2-, 3-I/II and 4-peak VPSD types, while the correspondingly mean relative humidity values are 58, 54, 72 and 67 %, respectively. The results also show the significant increase (from 0.25 to 0.40 μm) of the mean extra peak median radius in the accumulation mode for the 3-peak-II cases, which agrees with aerosol hygroscopic growth related to relative humidity and/or cloud or fog processing.

  12. Organic aerosols

    SciTech Connect

    Penner, J.E.

    1994-01-01

    Organic aerosols scatter solar radiation. They may also either enhance or decrease concentrations of cloud condensation nuclei. This paper summarizes observed concentrations of aerosols in remote continental and marine locations and provides estimates for the sources of organic aerosol matter. The anthropogenic sources of organic aerosols may be as large as the anthropogenic sources of sulfate aerosols, implying a similar magnitude of direct forcing of climate. The source estimates are highly uncertain and subject to revision in the future. A slow secondary source of organic aerosols of unknown origin may contribute to the observed oceanic concentrations. The role of organic aerosols acting as cloud condensation nuclei (CCN) is described and it is concluded that they may either enhance or decrease the ability of anthropogenic sulfate aerosols to act as CCN.

  13. Ambient Observations of the Soot Aging Process during the SHARP Intensive Field Campaign

    NASA Astrophysics Data System (ADS)

    Reed, C.; Collins, D. R.; Khalizov, A. F.; Zheng, J.; Zhang, R.

    2009-12-01

    flame was used to generate a polydisperse fresh soot aerosol. Then, using a differential mobility analyzer, a monodisperse, uncharged soot aerosol was injected into the environmental chamber. Observations of particle concentration, size, hygroscopicity, effective density, and light extinction and scattering properties were carried out over time using a tandem differential mobility analyzer system, an aerosol particle mass analyzer, a nephelometer and a cavity ringdown spectrometer. Results from preliminary analysis of the data collected during the campaign will be presented.

  14. Field Observations of the Processing of Organic Aerosol Particles and Trace Gases by Fogs and Clouds

    NASA Astrophysics Data System (ADS)

    Collett, J. L.; Herckes, P.

    2003-12-01

    In many environments, organic compounds account for a significant fraction of fine particle mass. Because the lifetimes of accumulation mode aerosol particles are governed largely by interactions with clouds, it is important to understand how organic aerosol particles are processed by clouds and fogs. Recently we have examined the organic composition of clouds and fogs in a variety of environments as well as how these fogs and clouds process organic aerosol particles and soluble organic trace gases. The investigations, conducted in Europe, North America, Central America, and the Pacific region, have included studies of polluted radiation fogs, orographic clouds in clean and polluted environments, and marine stratocumulus. Our results show that organic matter is a significant component of fog and cloud droplets. In polluted California radiation fogs, we observed concentrations of total organic carbon (TOC) ranging from 2 to 40 ppmC, with significantly lower concentrations measured in marine and continental clouds. An average of approximately 80 percent of organic matter was found in solution, while the remainder appears to be suspended material inside cloud and fog drops. Ultrafiltration measurements indicate that as much as half of the dissolved organic carbon is present in very large molecules with molecular weights in excess of 500 Daltons. Field measurements made using a two-stage cloud water collector reveal that organic matter tends to be enriched in smaller cloud or fog droplets. Consequently, removal of organic compounds by precipitating clouds or by direct cloud/fog drop deposition will be slowed due to the fact that small drops are incorporated less efficiently into precipitation and removed less efficiently by sedimentation or inertial impaction. Despite this trend, we have observed that sedimentation of droplets from long-lived radiation fogs provides a very effective mechanism for cleansing the atmosphere of carbonaceous aerosol particles, with organic

  15. Evaluation of MAX-DOAS aerosol retrievals by coincident observations using CRDS, lidar, and sky radiometer in Tsukuba, Japan

    NASA Astrophysics Data System (ADS)

    Irie, H.; Nakayama, T.; Shimizu, A.; Yamazaki, A.; Nagai, T.; Uchiyama, A.; Zaizen, Y.; Kagamitani, S.; Matsumi, Y.

    2015-01-01

    Coincident aerosol observations of Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS), Cavity Ring Down Spectroscopy (CRDS), lidar, and sky radiometer were conducted in Tsukuba, Japan on 5-18 October 2010. MAX-DOAS aerosol retrieval (for aerosol extinction coefficient and aerosol optical depth at 476 nm) was evaluated from the viewpoint of the need for a correction factor for oxygen collision complexes (O4 or O2-O2) absorption. The present study strongly supports this need, as systematic residuals at relatively high elevation angles (20 and 30°) were evident in MAX-DOAS profile retrievals conducted without the correction. However, adopting a single number for the correction factor (fO4 = 1.25) for all of the elevation angles led to systematic overestimation of near-surface aerosol extinction coefficients, as reported in the literature. To achieve agreement with all three observations, we limited the set of elevation angles to ≤ 10° and adopted an elevation-angle-dependent correction factor for practical profile retrievals with scattered light observations by a ground-based MAX-DOAS. With these modifications, we expect to minimize the possible effects of temperature-dependent O4 absorption cross section and uncertainty in DOAS fit on an aerosol profile retrieval, although more efforts are encouraged to quantitatively identify a physical explanation for the need of a correction factor.

  16. Evaluation of MAX-DOAS aerosol retrievals by coincident observations using CRDS, lidar, and sky radiometer inTsukuba, Japan

    NASA Astrophysics Data System (ADS)

    Irie, H.; Nakayama, T.; Shimizu, A.; Yamazaki, A.; Nagai, T.; Uchiyama, A.; Zaizen, Y.; Kagamitani, S.; Matsumi, Y.

    2015-07-01

    Coincident aerosol observations of multi-axis differential optical absorption spectroscopy (MAX-DOAS), cavity ring-down spectroscopy (CRDS), lidar, and sky radiometer were conducted in Tsukuba, Japan, on 5-18 October 2010. MAX-DOAS aerosol retrieval (for aerosol extinction coefficient and aerosol optical depth at 476 nm) was evaluated from the viewpoint of the need for a correction factor for oxygen collision complexes (O4 or O2-O2) absorption. The present study strongly supports this need, as systematic residuals at relatively high elevation angles (20 and 30°) were evident in MAX-DOAS profile retrievals conducted without the correction. However, adopting a single number for the correction factor (fO4 = 1.25) for all of the elevation angles led to systematic overestimation of near-surface aerosol extinction coefficients, as reported in the literature. To achieve agreement with all three observations, we limited the set of elevation angles to ≤10° and adopted an elevation-angle-dependent correction factor for practical profile retrievals with scattered light observations by a ground-based MAX-DOAS. With these modifications, we expect to minimize the possible effects of temperature-dependent O4 absorption cross section and uncertainty in DOAS fit on an aerosol profile retrieval, although more efforts are encouraged to quantitatively identify a physical explanation for the need of a correction factor.

  17. 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.

  18. SAS 3 observations of Cygnus X-1 - The intensity dips

    NASA Technical Reports Server (NTRS)

    Remillard, R. A.; Canizares, C. R.

    1984-01-01

    In general, the dips are observed to occur near superior conjunctions of the X-ray source, but one pair of 2-minute dips occurs when the X-ray source is closer to the observer than is the supergiant companion. The dips are analyzed spectrally with the aid of seven energy channels in the range 1.2-50 keV. Essentially, there is no change in the spectral index during the dips. Reductions in the count rates are observed at energies exceeding 6 keV for some of the dips, but the dip amplitude is always significantly greater in the 1.2-3 keV band. It is believed that absorption by partially ionized gas may best explain these results, since the observations of Pravdo et al. (1980) rule out absorption by unionized material. Estimates for the intervening gas density, extent, and distance from the X-ray source are presented. Attention is also given to the problems confronting the models for the injection of gas through the line of sight, believed to be inclined by approximately 30 deg from the binary pole.

  19. What We Can Learn About Aerosols from EOS-MISR Multi-Angle Remote Sensing Observations Over Ocean

    NASA Technical Reports Server (NTRS)

    Kahn, R.

    1999-01-01

    Multiangle, multispectral remote sensing observations, such as those anticipated from the Multiangle, multispectral remote sensing observations, such as those anticipated from the Earth Observing System (EOS) Multiangle Imaging SpectroRadiometer (MISR), promise to significantly improve our ability to constrain aerosol properties from space.

  20. PSC and volcanic aerosol routine observations in Antarctica by UV-visible ground-based spectrometry

    NASA Technical Reports Server (NTRS)

    Sarkissian, A.; Pommereau, J. P.; Goutail, F.

    1994-01-01

    Polar statospheric clouds (PSC) and stratospheric aerosol can be observed by ground-based UV-visible spectrometry by looking at the variation of the color of the sky during twilight. A radiative transfer model shows that reddenings are caused by high altitude (22-28 km) thin layers of scatterers, while low altitude (12-20 km) thick ones result in blueings. The color index method applied on 4 years of observations at Dumont d'Urville (67 deg S), from 1988 to 1991, shows that probably because the station is located at the edge of the vortex, dense PSC are uncommon. More unexpected is the existence of a systematic seasonal variation of the color of the twilight sky - bluer at spring - which reveals the formation of a dense scattering layer at or just above the tropopause at the end of the winter. Large scattering layers are reported above the station in 1991, first in August around 12-14 km, later in September at 22-24 km. They are attributed to volcanic aerosol from Mt Hudson and Mt Pinatubo respectively, which erupted in 1991. Inspection of the data shows that the lowest entered rapidly into the polar vortex but not the highest which remained outside, demonstrating that the vortex was isolated at 22-26 km.

  1. The importance of temporal collocation for the evaluation of aerosol models with observations

    NASA Astrophysics Data System (ADS)

    Schutgens, N. A. J.; Partridge, D. G.; Stier, P.

    2015-09-01

    It is often implicitly assumed that over suitably long periods the mean of observations and models should be comparable, even if they have different temporal sampling. We assess the errors incurred due to ignoring temporal sampling and show they are of similar magnitude as (but smaller than) actual model errors (20-60 %). Using temporal sampling from remote sensing datasets (the satellite imager MODIS and the ground-based sun photometer network AERONET) and three different global aerosol models, we compare annual and monthly averages of full model data to sampled model data. Our results show that sampling errors as large as 100 % in AOT (Aerosol Optical Thickness), 0.4 in AE (Ångström Exponent) and 0.05 in SSA (Single Scattering Albedo) are possible. Even in daily averages, sampling errors can be significant. More-over these sampling errors are often correlated over long distances giving rise to artificial contrasts between pristine and polluted events and regions. Additionally, we provide evidence that suggests that models will underestimate these errors. To prevent sampling errors, model data should be temporally collocated to the observations before any analysis is made. We also discuss how this work has consequences for in-situ measurements (e.g. aircraft campaigns or surface measurements) in model evaluation.

  2. Satellite Observations of Fires, Aerosols, and Precipitation and their Relationships in Monsoon Regions

    NASA Astrophysics Data System (ADS)

    Liu, Z.; Teng, W.; Chiu, L.; Rui, H.

    2006-05-01

    Monsoon regions are home of more than 50% of the world's population, with an annual growth rate of 2-4 percent. Understanding of regional environment is important in improving people's lives and reducing poverty. However, there are a number of issues that researchers are facing. First, there are sparse environmental data in those regions consisting mostly of developing countries. The lack of financial support makes difficult to deploy and conduct ground-based observations. Secondly, monsoon regions consist of large numbers of remote and unpopulated areas (e.g., forests), making observations difficult and expensive. In recent years, with the launches of NASA satellites (e.g., TRMM, Terra, etc.), large volumes of environmental data (e.g., fires, aerosols, and precipitation) have been collected over monsoon and other regions for research and applications. At the NASA Goddard Earth Sciences (GES) Data and Information Services Center (DISC) Distributed Active Archive Center (DAAC), a number of tools have been developed to facilitate data access and research. Among them, the TRMM Online Visualization and Analysis System (TOVAS, URL: http://disc2.nascom.nasa.gov/Giovanni/tovas/) and MODIS Online Visualization and Analysis System (MOVAS, URL: http://g0dup05u.ecs.nasa.gov/Giovanni/) are two user-friendly online tools allowing users to explore satellite data in both spatial and temporal dimensions and investigate their relationships. In this presentation, we will present recent results, including spatial and temporal distributions of fires, aerosols and precipitation in monsoon regions and their relationships.

  3. Organic aerosol evolution and transport observed at Mt. Cimone (2165 m a.s.l.), Italy, during the PEGASOS campaign

    NASA Astrophysics Data System (ADS)

    Rinaldi, M.; Gilardoni, S.; Paglione, M.; Sandrini, S.; Fuzzi, S.; Massoli, P.; Bonasoni, P.; Cristofanelli, P.; Marinoni, A.; Poluzzi, V.; Decesari, S.

    2015-10-01

    High-resolution aerosol mass spectrometer measurements were performed, for the first time, at the Mt. Cimone Global Atmosphere Watch (GAW) station between June and July 2012, within the EU project PEGASOS and the ARPA-Emilia-Romagna project SUPERSITO. Submicron aerosol was dominated by organics (63 %), with sulfate, ammonium and nitrate contributing the remaining 20, 9 and 7 %, respectively. Organic aerosol (OA) was in general highly oxygenated, consistent with the remote character of the site; our observations suggest that oxidation and secondary organic aerosol (SOA) formation processes occurred during aerosol transport to high altitudes. All of the aerosol component concentrations as well as the OA elemental ratios showed a clear daily trend, driven by the evolution of the planetary boundary layer (PBL) and by the mountain wind regime. Higher loadings and lower OA oxidation levels were observed during the day, when the site was within the PBL, and therefore affected by relatively fresh aerosol transported from lower altitudes. Conversely, lower loadings and higher OA oxidation levels were observed at night, when the top of Mt. Cimone resided in the free troposphere although affected by the transport of residual layers on several days of the campaign. Analysis of the elemental ratios in a Van Krevelen space shows that OA oxidation follows a slope comprised between -0.5 and -1, consistent with addition of carboxylic groups, with or without fragmentation of the parent molecules. The increase of carboxylic groups during OA ageing is confirmed by the increased contribution of organic fragments containing more than one oxygen atom in the free troposphere night-time mass spectra. Finally, positive matrix factorization was able to deconvolve the contributions of relatively fresh OA (OOAa) originating from the PBL, more aged OA (OOAb) present at high altitudes during periods of atmospheric stagnation, and very aged aerosols (OOAc) transported over long distances in the

  4. Evaluation of Observed and Modelled Aerosol Lifetimes Using Radioactive Tracers of Opportunity and an Ensemble of 19 Global Models

    NASA Technical Reports Server (NTRS)

    Kristiansen, N. I.; Stohl, A.; Olivie, D. J. L.; Croft, B.; Sovde, O. A.; Klein, H.; Christoudias, T.; Kunkel, D.; Leadbetter, S. J.; Lee, Y. H.; Zhang, K.; Tsigaridis, K.; Bauer, S. E.; Faluvegi, G. S.; Shindell, D.

    2016-01-01

    Aerosols have important impacts on air quality and climate, but the processes affecting their removal from the atmosphere are not fully understood and are poorly constrained by observations. This makes modelled aerosol lifetimes uncertain. In this study, we make use of an observational constraint on aerosol lifetimes provided by radionuclide measurements and investigate the causes of differences within a set of global models. During the Fukushima Dai-Ichi nuclear power plant accident of March 2011, the radioactive isotopes cesium-137 (Cs-137) and xenon-133 (Xe-133) were released in large quantities. Cesium attached to particles in the ambient air, approximately according to their available aerosol surface area. Cs-137 size distribution measurements taken close to the power plant suggested that accumulation mode (AM) sulfate aerosols were the main carriers of cesium. Hence, Cs-137 can be used as a proxy tracer for the AM sulfate aerosol's fate in the atmosphere. In contrast, the noble gas Xe-133 behaves almost like a passive transport tracer. Global surface measurements of the two radioactive isotopes taken over several months after the release allow the derivation of a lifetime of the carrier aerosol. We compare this to the lifetimes simulated by 19 different atmospheric transport models initialized with identical emissions of Cs-137that were assigned to an aerosol tracer with each model's default properties of AM sulfate, and Xe-133 emissions that were assigned to a passive tracer. We investigate to what extent the modelled sulfate tracer can reproduce the measurements, especially with respect to the observed loss of aerosol mass with time. Modelled Cs-137and Xe-133 concentrations sampled at the same location and times as station measurements allow a direct comparison between measured and modelled aerosol lifetime. The e-folding lifetime e, calculated from station measurement data taken between 2 and 9 weeks after the start of the emissions, is 14.3 days (95

  5. Evaluation of observed and modelled aerosol lifetimes using radioactive tracers of opportunity and an ensemble of 19 global models

    NASA Astrophysics Data System (ADS)

    Kristiansen, N. I.; Stohl, A.; Olivié, D. J. L.; Croft, B.; Søvde, O. A.; Klein, H.; Christoudias, T.; Kunkel, D.; Leadbetter, S. J.; Lee, Y. H.; Zhang, K.; Tsigaridis, K.; Bergman, T.; Evangeliou, N.; Wang, H.; Ma, P.-L.; Easter, R. C.; Rasch, P. J.; Liu, X.; Pitari, G.; Di Genova, G.; Zhao, S. Y.; Balkanski, Y.; Bauer, S. E.; Faluvegi, G. S.; Kokkola, H.; Martin, R. V.; Pierce, J. R.; Schulz, M.; Shindell, D.; Tost, H.; Zhang, H.

    2015-09-01

    Aerosols have important impacts on air quality and climate, but the processes affecting their removal from the atmosphere are not fully understood and are poorly constrained by observations. This makes modelled aerosol lifetimes uncertain. In this study, we make use of an observational constraint on aerosol lifetimes provided by radionuclide measurements and investigate the causes of differences within a set of global models. During the Fukushima Dai-Ichi nuclear power plant accident of March 2011, the radioactive isotopes cesium-137 (137Cs) and xenon-133 (133Xe) were released in large quantities. Cesium attached to particles in the ambient air, approximately according to their available aerosol surface area. 137Cs size distribution measurements taken close to the power plant suggested that accumulation-mode (AM) sulphate aerosols were the main carriers for the cesium. Hence, 137Cs can be used as a proxy tracer for the AM sulphate aerosol's fate in the atmosphere. In contrast, the noble gas 133Xe behaves almost like a passive transport tracer. Global surface measurements of the two radioactive isotopes taken over several months after the release allow the derivation of a lifetime of the carrier aerosol. We compare this to the lifetimes simulated by 19 different atmospheric transport models initialized with identical emissions of 137Cs that were assigned to an aerosol tracer with each model's default properties of AM sulphate, and 133Xe emissions that were assigned to a passive tracer. We investigate to what extent the modelled sulphate tracer can reproduce the measurements, especially with respect to the observed loss of aerosol mass with time. Modelled 37Cs and 133Xe concentrations sampled at the same location and times as station measurements allow a direct comparison between measured and modelled aerosol lifetime. The e-folding lifetime τe, calculated from station measurement data taken between two and nine weeks after the start of the emissions, is 14.3 days

  6. Evaluation of observed and modelled aerosol lifetimes using radioactive tracers of opportunity and an ensemble of 19 global models

    NASA Astrophysics Data System (ADS)

    Kristiansen, N. I.; Stohl, A.; Olivié, D. J. L.; Croft, B.; Søvde, O. A.; Klein, H.; Christoudias, T.; Kunkel, D.; Leadbetter, S. J.; Lee, Y. H.; Zhang, K.; Tsigaridis, K.; Bergman, T.; Evangeliou, N.; Wang, H.; Ma, P.-L.; Easter, R. C.; Rasch, P. J.; Liu, X.; Pitari, G.; Di Genova, G.; Zhao, S. Y.; Balkanski, Y.; Bauer, S. E.; Faluvegi, G. S.; Kokkola, H.; Martin, R. V.; Pierce, J. R.; Schulz, M.; Shindell, D.; Tost, H.; Zhang, H.

    2016-03-01

    Aerosols have important impacts on air quality and climate, but the processes affecting their removal from the atmosphere are not fully understood and are poorly constrained by observations. This makes modelled aerosol lifetimes uncertain. In this study, we make use of an observational constraint on aerosol lifetimes provided by radionuclide measurements and investigate the causes of differences within a set of global models. During the Fukushima Dai-Ichi nuclear power plant accident of March 2011, the radioactive isotopes cesium-137 (137Cs) and xenon-133 (133Xe) were released in large quantities. Cesium attached to particles in the ambient air, approximately according to their available aerosol surface area. 137Cs size distribution measurements taken close to the power plant suggested that accumulation-mode (AM) sulfate aerosols were the main carriers of cesium. Hence, 137Cs can be used as a proxy tracer for the AM sulfate aerosol's fate in the atmosphere. In contrast, the noble gas 133Xe behaves almost like a passive transport tracer. Global surface measurements of the two radioactive isotopes taken over several months after the release allow the derivation of a lifetime of the carrier aerosol. We compare this to the lifetimes simulated by 19 different atmospheric transport models initialized with identical emissions of 137Cs that were assigned to an aerosol tracer with each model's default properties of AM sulfate, and 133Xe emissions that were assigned to a passive tracer. We investigate to what extent the modelled sulfate tracer can reproduce the measurements, especially with respect to the observed loss of aerosol mass with time. Modelled 137Cs and 133Xe concentrations sampled at the same location and times as station measurements allow a direct comparison between measured and modelled aerosol lifetime. The e-folding lifetime τe, calculated from station measurement data taken between 2 and 9 weeks after the start of the emissions, is 14.3 days (95

  7. Application of aerosol optical properties to estimate aerosol type from ground-based remote sensing observation at urban area of northeastern China

    NASA Astrophysics Data System (ADS)

    Che, Huizheng; Zhao, Hujia; Wu, Yunfei; Xia, Xiangao; Zhu, Jun; Dubovik, Oleg; Estelles, Victor; Ma, Yanjun; Wang, Yangfeng; Wang, Hong; Wang, Yaqiang; Zhang, Xiaoye; Shi, Guangyu

    2015-09-01

    Aerosol optical properties were derived from ground-based sunphotometer observations between 2009-2013 at three urban sites of Shenyang, Anshan, Fushun in northeastern China. The annual means for extinction aerosol optical depths (EAOD) at 500 nm were 0.57±0.38, 0.52±0.35, and 0.41±0.31 at Shenyang, Anshan, Fushun, respectively. The corresponding annual means for the extinction Angstrom exponents (EAE) computed for the wavelengths of 440 and 870 nm were 0.86±0.32, 0.86±0.34 and 0.91±0.35, respectively, indicating that urban area of Northeast China were affected by both coarse and fine particles. Hygroscopic growth in summer and incursions of dust aerosols in spring were evidently revealed from the analysis of the relationship between EAE and δEAE (the EAE difference, δEAE=EAE(440,670)-EAE(670,870)). The annual mean absorption aerosol optical depths (AAOD440 nm) values at Shenyang, Anshan, Fushun were 0.15±0.11, 0.10±0.07, 0.08±0.04, respectively. The annual mean absorption Angstrom exponents (AAE440-870 nm) values were 0.86±0.24, 1.19±0.39, 1.33±0.36 at Shenyang, Anshan, Fushun, respectively. When the AAEs were close to unity at Anshan, the absorption aerosol particles evidently consisted of black carbon from coal combustion and motor vehicles. Larger AAEs at Fushun were indicative of absorbing aerosols mainly from biomass burning and mineral dust. The AAE at Shenyang was<1 which may be consistent with black carbon particles with absorbing or non-absorbing coatings. Analysis of the relationship between the AAEs and extinction Angstrom exponents showed that the aerosol populations at these three sites could be classified as "mixed-small particles" including anthropogenic particles and secondary organic aerosol with highly variable sphericity fractions.

  8. Observations of fluorescent and biological aerosol at a high-altitude site in central France

    NASA Astrophysics Data System (ADS)

    Gabey, A. M.; Vaitilingom, M.; Freney, E.; Boulon, J.; Sellegri, K.; Gallagher, M. W.; Crawford, I. P.; Robinson, N. H.; Stanley, W. R.; Kaye, P. H.

    2013-08-01

    an aerosol mass spectrometer (AMS; Aerodyne Inc.) suggests that aerosol reaching the site at night was more aged than that during the day, indicative of sampling the residual layer at night. Supplementary meteorological data and previous work also show that PdD lies in the residual layer/free troposphere at night, and this is thought to cause the observed diurnal cycles in organic-type and fluorescent aerosol particles. Based on the observed disparity between bacteria and fluorescent particle concentrations, fluorescent non-PBA is likely to be important in the WIBS-3 data and the surprisingly high fluorescent concentration in the residual layer/free troposphere raises questions about a ubiquitous background in continental air during the summer.

  9. Observations of fluorescent and biological aerosol at a high-altitude site in Central France

    NASA Astrophysics Data System (ADS)

    Gabey, A. M.; Vaitilingom, M.; Freney, E.; Boulon, J.; Sellegri, K.; Gallagher, M. W.; Crawford, I. P.; Robinson, N. H.; Stanley, W. R.; Kaye, P. H.

    2013-01-01

    more aged than that during the day, indicative of sampling the residual layer at night. Supplementary meteorological data and previous work also show that pdD lies in the residual layer/free troposphere at night, and this is thought to cause the observed diurnal cycles in organic-type and fluorescent aerosol particles. Based on the observed disparity between bacteria and fluorescent particle concentrations, fluorescent non-PBA is likely to be important in the WIBS-3 data and the surprisingly high fluorescent concentration in the residual layer/free troposphere raises questions about a ubiquitous background in continental air during the summer.

  10. Review on optical constants of Titan aerosols: Experimental results and modeling/observational data

    NASA Astrophysics Data System (ADS)

    Brassé, Coralie; Muñoz, Olga; Coll, Patrice; Raulin, François

    2014-05-01

    During the last years many studies have been performed to improve the experimental database of optical constants of Titan aerosols. Indeed, the determination of the optical constants of these particles is essential to quantify their capacity to absorb and to scatter solar radiation, and thus to evaluate their role on Titan's radiative balance and climate. The study of optical properties is also crucial to analyze and to better interpret many of Titan's observational data, in particular those acquired during the Cassini-Huygens mission. One way to determine Titan aerosols optical constant is to measure the optical constants of analogues of Titan complex organic material synthesized in the laboratory, usually named Titan's tholins (Sagan and Khare, 1979). But the optical constants depend on the chemical composition, the size and the shape of particles (Raulin et al., 2012). Those three parameters result from the experimental conditions such as energy source, gas mixing ratio, gas pressure, flow rate and irradiation time (Cable et al., 2012). Besides the determination of the refractive index in the laboratory, there are others methods using theoretical models or observational data. Nevertheless, theoretical models are based on laboratory data or/and observational data. The visible - near infrared spectral region of optical constants has been widely studied with laboratory analogues. Comparison of the obtained results suggest that tholins synthesized by Tran et al. (2003) and Majhoub et al. (2012) are the best representative of Titan aerosols with regards to their refractive indexes in this spectral region. The mid-infrared spectral range has been studied only by Imanaka et al. (2012) and slightly by Tran et al. (2003). In that spectral range, Titan tholins do not exhibit the features displayed by Kim and Courtin (2013) from Titan's observations. For spectral region of wavelengths smaller than 0.20µm or higher than 25µm, only the data from Khare et al. (1984) are

  11. Satellite observations of SO2, NO2, CO, and aerosol over China

    NASA Astrophysics Data System (ADS)

    Massie, S.; Wu, F.; Krotkov, N.; Levelt, P.; Chu, A.

    2009-04-01

    Satellite observations of SO2, NO2, CO, and aerosol over China are related to demographic population density, emissions inventories, industrial production, and thermal power plant geospatial distributions. Similarities and differences in the geospatial distributions of SO2, NO2, CO, and aerosol are identified. Ozone Monitoring Instrument (OMI) SO2 and NO2 atmospheric columns, Measurements of Pollution in the Troposphere (MOPITT) CO columns, and Moderate Resolution Imaging Spectroradiometer (MODIS) aerosol optical depths over China are analyzed during 2005-2007. A comparison of OMI NO2 and University of Columbia gridded population maps indicates a close correspondence between centers of enhanced NO2 and population, with enhanced NO2 and SO2 co-located along the geospatial arc from Shijiazhuang to Luoyang in Hebei, Shanxi, and Henan provinces of China. The region near 35 N and 112 E in northern Henan and southern Shanxi provinces has maxima in NO2, SO2, and CO, which is co-located with power plant number density and population centers. Trends in Global Ozone Monitoring Experiment (GOME) and Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) NO2 over China from 1996 - 2007, and OMI NO2 from 2004-2008, are compared, and placed in context, to other regions of the world. In accord with previous studies, trends in GOME and SCIAMACHY NO2 over China during 1996-2007 are positive, while trends over Europe and the United States are negative. OMI NO2 columns increase by 8.7 % per year over eastern China (20-30 N, 110-123 E) in the winters of 2004-2008.

  12. Aerosol optical depth derived from solar radiometry observations at northern mid-latitude sites

    SciTech Connect

    Laulainen, N.S.; Larson, N.R.; Michalsky, J.J.; Harrison, L.C.

    1994-01-01

    Routine, automated solar radiometry observations began with the development of the Mobile Automated Scanning Photometer (MASP) and its installation at the Rattlesnake Mountain Observatory (RMO). We have introduced a microprocessor controlled rotating shadowband radiometer (RSR), both the single detector and the multi-filter/detector (MFRSR) versions to replace the MASP. The operational mode of the RSRs is substantially different than the MASP or other traditional sun-tracking radiometers, because, by virtue of the automated rotating shadowband, the total and diffuse irradiance on a horizontal plane are measured and the direct-normal component deduced through computation from the total and diffuse components by the self-contained microprocessor. Because the three irradiance components are measured using the same detector for a given wavelength, the calibration coefficients are identical for each component, thus reducing errors when comparing them. The MFRSR is the primary radiometric instrument in the nine-station Quantitative Links Network (QLN) established in the eastern United States in late 1991. Data from this network are being used to investigate how cloud- and aerosol-induced radiative effects vary in time and with cloud structure and type over a mid-latitude continental region. This work supports the DOE Quantitative Links Program to quantify linkages between changes in atmospheric composition and climate forcing. In this paper we describe the setup of the QLN and present aerosol optical depth results from the on-going measurements at PNL/RMO, as well as preliminary results from the QLN. From the time-series of data at each site, we compare seasonal variability and geographical differences, as well as the effect of the perturbation to the stratosphere by Mt. Pinatubo. Analysis of the wavelength dependence of optical depth also provides information on the evolution and changes in the size distribution of the aerosols.

  13. Experimentally observed field–gas interaction in intense optical lattices

    SciTech Connect

    Graul, Jacob S.; Cornella, Barry M.; Ketsdever, Andrew D.; Lilly, Taylor C.; Shneider, Mikhail N.

    2013-12-09

    When a gas perturbed by a laser interference pattern, an optical lattice, exhibits a periodic modulation of its refractive index, strong Bragg diffraction of the perturbing light can occur. This scattering reduces the field's ability to further manipulate the gas. Experimental observations of Bragg scattering, evidence of a two-way coupling, are compared to the evolution of the light fields calculated by solutions to the wave equation. Comparison indicates momentum deposition as a prime contributor to the shape of the scattering function vs. lattice velocity, a rationale further supported through additional direct simulation Monte Carlo simulation.

  14. Aerosol measurements at 60 m during April 1994 remote cloud study intensive operating period (RCS/IOP)

    SciTech Connect

    Leifer, R.; Albert, B.; Lee, N.; Knuth, R.H.

    1996-04-01

    Aerosol measurements were made at the Southern Great Plains Site of the Atmospheric Radiation Measurement (ARM) program. Many types of air masses pass over this area, and on the data acquisition day, extremly low aerosol scattering coefficients were seen. A major effort was placed on providing some characterization of the aerosol size distribution. Data is currently available from the experimental center.

  15. Comparison of Columnar Water Vapor Measurements During The Fall 1997 ARM Intensive Observation Period: Solar Transmittance Methods

    NASA Technical Reports Server (NTRS)

    Schmid, B.; Michalsky, J. J.; Slater, D. W.; Barnard, J. C.; Halthore, R. N.; Liljegren, J. C.; Holben, B. N.; Eck, T. F.; Livingston, J. M.; Russell, P. B.

    2000-01-01

    In the fall of 1997, during an Intensive Observation Period (IOP), the Atmospheric Radiation Measurement (ARM) program conducted a study of water vapor abundance measurement at its Southern Great Plains (SGP) site. Among a large number of instruments, four sun-tracking radiometers were present to measure the columnar water vapor (CWV). All four solar radiometers retrieve CWV by measuring total solar transmittance in the 0.94-gm water vapor absorption band and subtracting contributions due to Rayleigh, ozone and aerosol transmittances. The aerosol optical depth comparisons among the same four radiometers has been presented elsewhere (Geophys. Res. Lett., 26, 17, 2725-2728, 1999). We have used three different methods to retrieve CWV. In a first round of comparison no attempt was made to standardize on the same radiative transfer model and its underlying water vapor spectroscopy. In the second round of comparison we used the same line-by-line code (which includes recently corrected H2O spectroscopy) to retrieve CAN from all four suntracking radiometers. This decreased the mean CWV by 8% or 13%. The spread of 8% in the solar radiometer results found when using the same model is an indication of the other-than-model uncertainties involved in determining CWV from solar transmittance measurements with current instrumentation.

  16. Trans-Pacific transport and evolution of aerosols: evaluation of quasi-global WRF-Chem simulation with multiple observations

    NASA Astrophysics Data System (ADS)

    Hu, Zhiyuan; Zhao, Chun; Huang, Jianping; Leung, L. Ruby; Qian, Yun; Yu, Hongbin; Huang, Lei; Kalashnikova, Olga V.

    2016-05-01

    A fully coupled meteorology-chemistry model (WRF-Chem, the Weather Research and Forecasting model coupled with chemistry) has been configured to conduct quasi-global simulation for 5 years (2010-2014) and evaluated with multiple observation data sets for the first time. The evaluation focuses on the simulation over the trans-Pacific transport region using various reanalysis and observational data sets for meteorological fields and aerosol properties. The simulation generally captures the overall spatial and seasonal variability of satellite retrieved aerosol optical depth (AOD) and absorbing AOD (AAOD) over the Pacific that is determined by the outflow of pollutants and dust and the emissions of marine aerosols. The assessment of simulated extinction Ångström exponent (EAE) indicates that the model generally reproduces the variability of aerosol size distributions as seen by satellites. In addition, the vertical profile of aerosol extinction and its seasonality over the Pacific are also well simulated. The difference between the simulation and satellite retrievals can be mainly attributed to model biases in estimating marine aerosol emissions as well as the satellite sampling and retrieval uncertainties. Compared with the surface measurements over the western USA, the model reasonably simulates the observed magnitude and seasonality of dust, sulfate, and nitrate surface concentrations, but significantly underestimates the peak surface concentrations of carbonaceous aerosol likely due to model biases in the spatial and temporal variability of biomass burning emissions and secondary organic aerosol (SOA) production. A sensitivity simulation shows that the trans-Pacific transported dust, sulfate, and nitrate can make significant contribution to surface concentrations over the rural areas of the western USA, while the peaks of carbonaceous aerosol surface concentrations are dominated by the North American emissions. Both the retrievals and simulation show small

  17. Observations of Ozone and Aerosols Over Mexico and Gulf of Mexico During INTEX- B/MILAGRO Field Experiment

    NASA Astrophysics Data System (ADS)

    Butler, C. F.; Browell, E. V.; Hair, J. W.; Fenn, M. A.; Notari, A.; Kooi, S. A.; Ismail, S.; Avery, M. A.; Pierce, R. B.

    2007-12-01

    The NASA Langley Research Center's Differential Absorption Lidar (LaRC/DIAL) system has been used to measure ozone and aerosol distributions in many airborne global tropospheric and stratospheric campaigns since 1980. The tropospheric configuration of this system was flown on the NASA DC-8 during the INTEX-B (Phase-I)/MILAGRO (I/M) field experiment, which was conducted from 24 February to 22 March 2006 over Mexico and the Gulf of Mexico. DIAL remote profile measurements were made from near the surface to above the tropopause along the flight track of the DC-8 with a small data void region of 750 m above and below the aircraft. Aerosol scattering ratios were determined at two wavelengths for a gross estimation of the relative size of the observed particles and measurements of aerosol depolarization were made to distinguish nonspherical aerosols, such as dust and some aerosols in aged fire plumes. In situ measurements of ozone from the FASTOZ instrument on the DC-8 were used to constrain the interpolation of the nadir and zenith ozone lidar measurements, which then provided an estimate of the entire tropospheric ozone profile along the flight track. A first order correction for aerosol attenuation was made to the aerosol profiles by using an assumed extinction-to- backscatter ratio to better characterize the attenuation by thick aerosol layers. The DIAL system was used to determine the large-scale variability and context of air masses being sampled in situ on the DC-8 and to direct the in situ sampling strategy in real time. Plumes from biomass burning in southern Mexico were often observed in the free troposphere over the Gulf of Mexico and over eastern Mexico. The Mexico City (MC) pollution plume was readily apparent with high ozone (>100 ppbv), high aerosol scattering (S>20), and enhanced aerosol depolarization (D>10%). The top of the MC pollution extended to a depth of about 2.5 km AGL. Some observations showed the MC plume spilling out over the mountains to

  18. SOLAR H{alpha} OSCILLATIONS FROM INTENSITY AND DOPPLER OBSERVATIONS

    SciTech Connect

    Jackiewicz, Jason; Balasubramaniam, K. S.

    2013-03-01

    Chromospheric wave activity around flares and filaments has been a research focus for years, and could provide indirect measurements of local conditions that are not otherwise accessible. One interesting observed phenomenon is oscillations in filaments, activated by distant flares and the large-scale waves they produce. Characteristics of these oscillations, such as periods, amplitudes, and lifetimes, can provide unique information about the filament. We measure oscillation properties in flares and filaments from H{alpha} chromospheric data using a new method that provides important spatial and frequency content of the dynamics. We apply the method to two flare events where filaments are observed to oscillate and determine their properties. We find strong oscillatory signal in flaring active regions in the chromosphere over a range of frequencies. Two filaments are found to oscillate without any detectable chromospheric wave acting as an activation mechanism. We find that filaments oscillate with periods of tens of minutes, but variations are significant at small spatial scales along the filamentary region. The results suggest that there is a frequency dependence of the oscillation amplitude, as well as a spatial dependence along single filaments that is more difficult to quantify. It also appears that the strength of the oscillations does not necessarily depend on the strength of the trigger, although there are other possible effects that make this conclusion preliminary. Applications of this technique to other events and different data sets will provide important new insights into the local energy densities and magnetic fields associated with dynamic chromospheric structures.

  19. A Study of Stratospheric Aerosols and Their Effect on Inorganic Chlorine Partitioning Using Balloon, In Situ, and Satellite Observations

    NASA Technical Reports Server (NTRS)

    Osterman, G. B.; Salawitch, R. J.; Sen, B.; Toon, G. C.

    1999-01-01

    Heterogeneous reactions on the surface of aerosols lead to a decrease in the concentration of nitrogen radicals and an increase in the concentration of chlorine and hydrogen radical species. As a consequence, enhanced sulfate aerosol levels in the lower stratosphere resulting from volcanic eruptions lead to lower concentrations of ozone due to more rapid loss by chlorine and hydrogen radicals. This study focuses on continuing the effort to quantify the effect of sulfate aerosols on the partitioning of inorganic chlorine species at midlatitudes. The study begins with an examination of balloon-borne measurements of key chlorine species obtained by the JPL MkIV interferometer for different aerosol loading conditions. A detailed comparison of the response of HCl to variations in aerosol surface area observed by MkIV, ER-2 instruments, HALOE, and ATMOS is carried out by examining HCl vs CH4 correlation diagrams, since CH4 is the only tracer measured on each platform. Finally, the consistency between theory and observed changes in ClO and HCl due to variations in aerosol surface area is examined.

  20. Aerosol Optical Depths over Oceans: a View from MISR Retrievals and Collocated MAN and AERONET in Situ Observations

    NASA Technical Reports Server (NTRS)

    Witek, Marcin L.; Garay, Michael J.; Diner, David J.; Smirnov, Alexander

    2013-01-01

    In this study, aerosol optical depths over oceans are analyzed from satellite and surface perspectives. Multiangle Imaging SpectroRadiometer (MISR) aerosol retrievals are investigated and validated primarily against Maritime Aerosol Network (MAN) observations. Furthermore, AErosol RObotic NETwork (AERONET) data from 19 island and coastal sites is incorporated in this study. The 270 MISRMAN comparison points scattered across all oceans were identified. MISR on average overestimates aerosol optical depths (AODs) by 0.04 as compared to MAN; the correlation coefficient and root-mean-square error are 0.95 and 0.06, respectively. A new screening procedure based on retrieval region characterization is proposed, which is capable of substantially reducing MISR retrieval biases. Over 1000 additional MISRAERONET comparison points are added to the analysis to confirm the validity of the method. The bias reduction is effective within all AOD ranges. Setting a clear flag fraction threshold to 0.6 reduces the bias to below 0.02, which is close to a typical ground-based measurement uncertainty. Twelve years of MISR data are analyzed with the new screening procedure. The average over ocean AOD is reduced by 0.03, from 0.15 to 0.12. The largest AOD decrease is observed in high latitudes of both hemispheres, regions with climatologically high cloud cover. It is postulated that the screening procedure eliminates spurious retrieval errors associated with cloud contamination and cloud adjacency effects. The proposed filtering method can be used for validating aerosol and chemical transport models.

  1. Exceptional aerosol pollution plume observed using a new ULA-lidar approach

    NASA Astrophysics Data System (ADS)

    Chazette, Patrick

    2016-09-01

    An exceptional particulate pollution event was sampled in June 2005 over the Ardèche region in Southern France. Airborne (at the wavelength of 355 nm) and ground-based (at the wavelength of 532 nm) lidars performed measurements simultaneously. Airborne observations were performed from an ultra-light aircraft (ULA); they offer an opportunity to test a new method for inversing lidar profiles which enables their quantitative use while the airplane flies in a scattering layer. Using the results of this approach and the ground-based lidar measurements, the aerosol plumes have been optically quantified and the diversity of particle sources (from Western Europe, North Africa and even North America) which contributed to the event has been highlighted using both spaceborne observations and multiple air mass back-trajectories.

  2. Stratospheric aerosol and gas experiment III (SAGE III) aerosol and trace gas measurements for Earth Observing System (EOS)

    NASA Technical Reports Server (NTRS)

    Mccormick, M. P.; Chu, W. P.; Zawodny, J. M.; Mauldin, L. E.; Mcmaster, L. R.

    1991-01-01

    The SAGE III instrument, the latest in a series of satellite-based instruments employing the self-calibrating solar occultation technique to monitor aerosols and trace gases in the atmosphere, and potential contributions to monitoring global change and other EOS objectives are described. Uses of these data are illustrated with SAGE I and II long-term ozone, aerosol, and water vapor data. The SAGE III instrument will improve the SAM II and SAGE data products with greater overall accuracy, and will provide the ability to extend these measurements over a greater height range. SAGE III will provide long-term self-calibrating global data sets from the midtroposphere to mesosphere, which will contribute greatly to the quantification and understanding of global change.

  3. 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

  4. Possible interaction of meteor explosion with stratospheric aerosols on cloud nucleation based on 2011 observations.

    NASA Astrophysics Data System (ADS)

    Courty, M.-A.; Vaillant, M.; Benoit, R.

    2012-04-01

    The lack of knowledge on the nature and the variability through time of stratospheric aerosols strongly constrains the understanding of precipitation events at local to regional scales. Along other causes, meteoroid ablation is assumed to creating significant disturbances on the upper stratosphere layers, particularly by debris production and flash heating. Due to the lack of observations, the impact on cloud and precipitation processes of cosmic debris that are annually delivered to Earth is not taken into account in climate modeling. Here we report on the data collected from 2011 cosmic events that occurred on the Angles village in Pyrenees Orientales (France). The trajectory of a meteor was traced by the CNES from Toulouse (France) to the Pyrenees boarder with Spain where it exploded at high altitude on August 2. 30 hours later, a detonation with debris pulverization at the ground was recorded at the same location across a restricted area. In the following days, unusual heavy rainstorms and violent fall of hailstones were locally recorded from the Pyrenees to the coastal plain. Meticulous sampling of the 2011 August 3rd debris fall and of the soils affected by the subsequent precipitation events has been performed. A similar assemblage of organic and mineral components of stratospheric origin was revealed. It is formed of aliphatic carbonaceous polymorphs of terrestrial origin, volcanic dust, charred and fresh organic grains, fine grained sandstones with native metals and micrometeorite spherules. Microscopic assemblage, isotopes and geochemical data show composite materials formed of imbricated terrestrial and extra-terrestrial components. Based on their C14 and C13 values the terrestrial carbonaceous polymorphs appear to derive from fossil combustible. The fine imbrication of all the other terrestrial components with the carbonaceous polymorphs indicates a common origin from the upper stratosphere. The mixing of the extraterrestrial debris with the

  5. The Southern Ocean Clouds, Radiation, Aerosol Transport Experimental Study (SOCRATES): An Observational Campaign for Determining Role of Clouds, Aerosols and Radiation in Climate System

    NASA Astrophysics Data System (ADS)

    McFarquhar, G. M.; Wood, R.; Bretherton, C. S.; Alexander, S.; Jakob, C.; Marchand, R.; Protat, A.; Quinn, P.; Siems, S. T.; Weller, R. A.

    2014-12-01

    The Southern Ocean (SO) region is one of the cloudiest on Earth, and as such clouds determine its albedo and play a major role in climate. Evidence shows Earth's climate sensitivity and the Intertropical Convergence Zone location depend upon SO clouds. But, climate models are challenged by uncertainties and biases in the simulation of clouds, aerosols, and air-sea exchanges in this region which trace back to a poor process-level understanding. Due to the SO's remote location, there have been sparse observations of clouds, aerosols, precipitation, radiation and the air-sea interface apart from those from satellites. Plans for an upcoming observational program, SOCRATES, are outlined. Based on feedback on observational and modeling requirements from a 2014 workshop conducted at the University of Washington, a plan is described for obtaining a comprehensive dataset on the boundary-layer structure and associated vertical distributions of liquid and mixed-phase cloud and aerosol properties across a range of synoptic settings, especially in the cold sector of cyclonic storms. Four science themes are developed: improved climate model simulation of SO cloud and boundary layer structure in a rapidly varying synoptic setting; understanding seasonal and synoptic variability in SO cloud condensation and ice nucleus concentration and the role of local biogenic sources; understanding supercooled liquid and mixed-phase clouds and their impacts; and advancing retrievals of clouds, precipitation, aerosols, radiation and surface fluxes. Testable hypotheses for each theme are identified. The observational strategy consists of long-term ground-based observations from Macquarie Island and Davis, continuous data collection onboard Antarctic supply ships, satellite retrievals, and a dedicated field campaign covering 2 distinct seasons using in-situ and remote sensors on low- and high-altitude aircraft, UAVs, and a ship-borne platform. A timeline for these activities is proposed.

  6. Observed perturbations of the Earth's Radiation Budget - A response to the El Chichon stratospheric aerosol layer?

    NASA Technical Reports Server (NTRS)

    Ardanuy, P. E.; Kyle, H. L.

    1986-01-01

    The Earth Radiation Budget experiment, launched aboard the Nimbus-7 polar-orbiting spacecraft in late 1978, has now taken over seven years of measurements. The dataset, which is global in coverage, consists of the individual components of the earth's radiation budget, including longwave emission, net radiation, and both total and near-infrared albedos. Starting some six months after the 1982 eruption of the El Chichon volcano, substantial long-lived positive shortwave irradiance anomalies were observed by the experiment in both the northern and southern polar regions. Analysis of the morphology of this phenomena indicates that the cause is the global stratospheric aerosol layer which formed from the cloud of volcanic effluents. There was little change in the emitted longwave in the polar regions. At the north pole the largest anomaly was in the near-infrared, but at the south pole the near UV-visible anomaly was larger. Assuming an exponential decay, the time constant for the north polar, near-infrared anomaly was 1.2 years. At mid- and low latitudes the effect of the El Chichon aerosol layer could not be separated from the strong reflected-shortwave and emitted-longwave perturbations issuing from the El Nino/Southern Oscillation event of 1982-83.

  7. Importing ozone precursors and aerosols to the North American free troposphere: An analysis of peroxyacetyl nitrate and aerosol observations at Mount Bachelor

    NASA Astrophysics Data System (ADS)

    Fischer, Emily V.

    Exposure to aerosols and ozone poses a health threat to a large portion of the U.S. population. Domestic sources and a global background burden both contribute to ambient concentrations, and East Asia is currently a fast growing air pollution source. This dissertation presents results from two projects, and in each case observations from the Mount Bachelor Observatory (MBO, 43.980 N, 121.69° W; 2.7 km amsl) play a central role in the analysis. The first component of this dissertation presents an analysis of the first multi-year springtime measurements of peroxyacetyl nitrate (PAN) in the free troposphere over the Pacific Northwest. The measurements were made by gas chromatography with electron capture detector during spring 2008, 2009, and 2010. Springtime mean PAN mixing ratios at MBO varied from 100 pptv to 152 pptv. The observed relationship between PAN and 03 in a descending Asian air mass was used to derive an ozone production efficiency of 51-73 mol mol-1. I combined the observed variability in PAN and ozone at MBO with a range of trends to determine the observational requirements for trend detection. If springtime PAN mixing ratios increase at a rate of 4% per year due to rising Asian emissions, we would detect a trend with 13 years of measurements. If the corresponding trend in ozone is 1% per year, the trend in ozone will be detected on approximately the same timescale. The second component of this dissertation addresses the physical evolution of Asian aerosols and their impact on U.S. air quality. I showed that approximately 50% of the interannual variability in springtime average PM2.5 in remote areas of the U.S. Pacific Northwest can be explained by changes in Asian dust emissions. Next I identified 7 plumes of Asian origin within observations of sub --microm aerosol scattering and absorption from MBO. The average sub-microm scattering Angstrom exponent for the plumes was significantly larger than the same parameter observed closer to Asia, suggesting

  8. Interpreting the Ultraviolet Aerosol Index Observed with the OMI Satellite Instrument to Understand Absorption by Organic Carbon Aerosols and Implications for Atmospheric Oxidation

    NASA Astrophysics Data System (ADS)

    Hammer, M. S.; Martin, R.; van Donkelaar, A.; Buchard, V.; Torres, O.; Ridley, D. A.; Spurr, R. J. D.

    2015-12-01

    Absorption of solar radiation by aerosols plays a major role in radiative forcing and atmospheric photochemistry. Many atmospheric chemistry models tend to overestimate tropospheric OH concentrations compared to observations. Accurately representing aerosol absorption in the UV could help rectify the discrepancies between simulated and observed OH concentrations. We develop a simulation of the Ultraviolet Aerosol Index (UVAI), using the 3-D chemical transport model GEOS-Chem coupled with the Vector Linearized Discrete Ordinate Radiative Transfer model (VLIDORT). The simulation is applied to interpret UVAI observations from the Ozone Monitoring Instrument (OMI). Simulated and observed values are highly consistent in regions where mineral dust dominates the UVAI, but a large negative bias (-0.4 to -1.0) exists between simulated and observed values in biomass burning regions. We implement optical properties for absorbing organic aerosol, known as brown carbon (BrC), into GEOS-Chem and evaluate the simulation with observed UVAI values over biomass burning regions. The spectral dependence of absorption after adding BrC to the model is broadly consistent with reported observations for biomass burning aerosol, with Absorbing Angstrom Exponent (AAE) values ranging from 2.7 in the UV to 1.3 across the UV-Near IR spectrum. The addition of absorbing BrC decreases the mean bias between simulated and OMI UVAI values from -0.60 to -0.08 over North Africa in January, from -0.40 to -0.003 over South Asia in April, from -1.0 to -0.24 over southern Africa in July, and from -0.50 to +0.34 over South America in September. We assess the effect of the additional UV absorption by BrC on atmospheric photochemistry by examining ozone photolysis frequencies (J(O(1D))) and tropospheric OH concentrations in GEOS-Chem. The inclusion of BrC decreases J(O(1D)) and OH by up to 35% over biomass burning regions, and reduces the global bias in OH.

  9. CCN Activity of Organic Aerosols Observed Downwind of Urban Emissions during CARES

    SciTech Connect

    Mei, Fan; Setyan, Ari; Zhang, Qi; Wang, J. X.

    2013-12-17

    During the Carbonaceous Aerosols and Radiative Effects Study (CARES), activation fraction of size-resolved aerosol particles and aerosol chemical composition were characterized at the T1 site (~60 km downwind of Sacramento, California) from 10 June to 28 June 2010. The hygroscopicity of CCN-active particles (KCCN) with diameter from 100 to 170 nm, derived from the size-resolved activated fraction, varied from 0.10 to 0.21, with an average of 0.15, which was substantially lower than that proposed for continental sites in earlier studies. The low KCCN value was due to the high organic volume fraction, averaged over 80% at the T1 site. The derived KCCN exhibited little diurnal variation, consistent with the relatively constant organic volume fraction observed. At any time, over 90% of the size selected particles with diameter between 100 and 171nm were CCN active, suggesting most particles within this size range were aged background particles. Due to the large organic volume fraction, organic hygroscopicity (Korg) strongly impacted particle hygroscopicity and therefore calculated CCN concentration. For vast majority of the cases, an increase of Korg from 0.03 to 0.18, which are within the typical range, doubled the calculated CCN concentration. Organic hygroscopicity was derived from KCCN and aerosol chemical composition, and its variations with the fraction of total organic mass spectral signal at m/z 44 (f44) and O:C were compared to results from previous studies. Overall, the relationships between Korg and f44 are quite consistent for organic aerosol (OA) observed during field studies and those formed in smog chamber. Compared to the relationship between Korg and f44, the relationship between Korg and O:C exhibits more significant differences among different studies, suggesting korg may be better parameterized using f44. A

  10. Optical and microphysical properties of mineral dust and biomass burning aerosol observed over Warsaw on 10th July 2013

    NASA Astrophysics Data System (ADS)

    Janicka, Lucja; Stachlewska, Iwona; Veselovskii, Igor; Baars, Holger

    2016-04-01

    Biomass burning aerosol originating from Canadian forest fires was widely observed over Europe in July 2013. Favorable weather conditions caused long-term westward flow of smoke from Canada to Western and Central Europe. During this period, PollyXT lidar of the University of Warsaw took wavelength dependent measurements in Warsaw. On July 10th short event of simultaneous advection of Canadian smoke and Saharan dust was observed at different altitudes over Warsaw. Different origination of both air masses was indicated by backward trajectories from HYSPLIT model. Lidar measurements performed with various wavelength (1064, 532, 355 nm), using also Raman and depolarization channels for VIS and UV allowed for distinguishing physical differences of this two types of aerosols. Optical properties acted as input for retrieval of microphysical properties. Comparisons of microphysical and optical properties of biomass burning aerosols and mineral dust observed will be presented.

  11. Global pollution aerosol monitoring (GPAM) in the atmospheric boundary layer using future earth observing satellite remote sensing

    NASA Astrophysics Data System (ADS)

    Qu, Jianhe; Kafatos, Menas; Yang, Ruixin; Chiu, Long S.; Riebau, Allen R.

    2003-04-01

    Global pollution aerosol monitoring is a very important climatic and environmental problem. It affects not only human health but also ecological systems. Because most pollution aerosols are concentrated in the atmospheric boundary layer where human, animal and vegetation live, global pollution aerosol stuides have been an important topic since about a decade ago. Recently, many new chemistry remote sensing satellite systems, such as NASA's Aura (EOS-CHEM), have been established. However, pollution aerosols in the atmospheric boundary layer cannot be detected using current remote sensing technologies. George Mason University (GMU) proposes to design scientific algorithms and technologies to monitor the atmospheric boundary layer pollution aerosols, using both satellite remote sensing measurements and ground measurements, collaborating with NASA and the United States Department of Agriculture (USDA)/Forest Services (FS). Boundary layer pollution aerosols result from industrial pollution, desert dust storms, smoke from wildfires and biomass burning, volcanic eruptions, and from other trace gases. The current and next generation satellite instruments, such as The Ozone Mapping and Profiler Suite (OMPS), Ozone Monitoring Instrument (OMI), Thermal Emission Spectrometer (TES), and High Resolution Dynamics Limb Sounder (HIRDLS) can be used for this study. Some surface measurements from USDA/FS and other agencies may also be used in this study. We will discuss critical issues for GPAM in the boundary layer using Earth observing satellite remote sensing in detail in this paper.

  12. Multi-Decadal Aerosol Variations from 1980 to 2009: A Perspective from Observations and a Global Model

    NASA Technical Reports Server (NTRS)

    Chin, Mian; Diehl, T.; Tan, Q.; Prospero, J. M.; Kahn, R. A.; Remer, L. A.; Yu, H.; Sayer, A. M.; Bian, H.; Geogdzhayev, I. V.; Holben, B. N.; Howell, S. G.; Huebert, B. J.; Hsu, N. C.; Kim, D.; Kucsera, T. L.; Levy, R. C.; Mishchenko, M. I.; Pan, X.; Quinn, P. K.; Schuster, G. L.; Streets, D. G.; Strode, S. A.; Torres, O.; Zhao, X.-P.

    2014-01-01

    Aerosol variations and trends over different land and ocean regions during 1980-2009 are analyzed with the Goddard Chemistry Aerosol Radiation and Transport (GOCART) model and observations from multiple satellite sensors and ground-based networks. Excluding time periods with large volcanic influences, the tendency of aerosol optical depth (AOD) and surface concentration over polluted land regions is consistent with the anthropogenic emission changes.The largest reduction occurs over Europe, and regions in North America and Russia also exhibit reductions. On the other hand, East Asia and South Asia show AOD increases, although relatively large amount of natural aerosols in Asia makes the total changes less directly connected to the pollutant emission trends. Over m