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Sample records for affecting cloud properties

  1. A Characterization of Cirrus Cloud Properties That Affect Laser Propagation

    DTIC Science & Technology

    2008-05-01

    13. SUPPLEMENTARY NOTES - Reprinted from Journal of Applied Meteorology and Climatology, Vol. 47, pp 1322 -1336 14. ABSTRACT Future high-altitude...UNCL UNL 10 Standard Form 298 (Rev. 8/98) Prescribed by ANSI Std Z3918 AFRL-RV-HA-TR-2008-1050 1322 JOURNAL OF APPLIED METEOROLOGY AND CLIMATOLOGY VOIIt...retrieved from actual n bo t and to p atindicers The lasermmotha d topmost cloud c mputational layers. The l s r path cirrus measurements are used to

  2. Polarimetric Retrievals of Surface and Cirrus Clouds Properties in the Region Affected by the Deepwater Horizon Oil Spill

    NASA Technical Reports Server (NTRS)

    Ottaviani, Matteo; Cairns, Brian; Chowdhary, Jacek; Van Diedenhoven, Bastiaan; Knobelspiesse, Kirk; Hostetler, Chris; Ferrare, Rich; Burton, Sharon; Hair, John; Obland, Michael D.; Rogers, Raymond

    2012-01-01

    In 2010, the Goddard Institute for Space Studies (GISS) Research Scanning Polarimeter (RSP) performed several aerial surveys over the region affected by the oil spill caused by the explosion of the Deepwater Horizon offshore platform. The instrument was deployed on the NASA Langley B200 aircraft together with the High Spectral Resolution Lidar (HSRL), which provides information on the distribution of the aerosol layers beneath the aircraft, including an accurate estimate of aerosol optical depth. This work illustrates the merits of polarization measurements in detecting variations of ocean surface properties linked to the presence of an oil slick. In particular, we make use of the degree of linear polarization in the glint region, which is severely affected by variations in the refractive index but insensitive to the waviness of the water surface. Alterations in the surface optical properties are therefore expected to directly affect the polarization response of the RSP channel at 2264 nm, where both molecular and aerosol scattering are negligible and virtually all of the observed signal is generated via Fresnel reflection at the surface. The glint profile at this wavelength is fitted with a model which can optimally estimate refractive index, wind speed and direction, together with aircraft attitude variations affecting the viewing geometry. The retrieved refractive index markedly increases over oil-contaminated waters, while the apparent wind speed is significantly lower than in adjacent uncontaminated areas, suggesting that the slick dampens high-frequency components of the ocean wave spectrum. The constraint on surface reflectance provided by the short-wave infrared channels is a cornerstone of established procedures to retrieve atmospheric aerosol microphysical parameters based on the inversion of the RSP multispectral measurements. This retrieval, which benefits from the ancillary information provided by the HSRL, was in this specific case hampered by

  3. Cloud Processed CCN Affect Cloud Microphysics

    NASA Astrophysics Data System (ADS)

    Hudson, J. G.; Noble, S. R., Jr.; Tabor, S. S.

    2015-12-01

    Variations in the bimodality/monomodality of CCN spectra (Hudson et al. 2015) exert opposite effects on cloud microphysics in two aircraft field projects. The figure shows two examples, droplet concentration, Nc, and drizzle liquid water content, Ld, against classification of CCN spectral modality. Low ratings go to balanced separated bimodal spectra, high ratings go to single mode spectra, strictly monomodal 8. Intermediate ratings go merged modes, e.g., one mode a shoulder of another. Bimodality is caused by mass or hygroscopicity increases that go only to CCN that made activated cloud droplets. In the Ice in Clouds Experiment-Tropical (ICE-T) small cumuli with lower Nc, greater droplet mean diameters, MD, effective radii, re, spectral widths, σ, cloud liquid water contents, Lc, and Ld were closer to more bimodal (lower modal ratings) below cloud CCN spectra whereas clouds with higher Nc, smaller MD, re, σ, and Ld were closer to more monomodal CCN (higher modal ratings). In polluted stratus clouds of the MArine Stratus/Stratocumulus Experiment (MASE) clouds that had greater Nc, and smaller MD, re, σ, Lc, and Ld were closer to more bimodal CCN spectra whereas clouds with lower Nc, and greater MD, re, σ, Lc, and Ld were closer to more monomodal CCN. These relationships are opposite because the dominant ICE-T cloud processing was coalescence whereas chemical transformations (e.g., SO2 to SO4) were dominant in MASE. Coalescence reduces Nc and thus also CCN concentrations (NCCN) when droplets evaporate. In subsequent clouds the reduced competition increases MD and σ, which further enhance coalescence and drizzle. Chemical transformations do not change Nc but added sulfate enhances droplet and CCN solubility. Thus, lower critical supersaturation (S) CCN can produce more cloud droplets in subsequent cloud cycles, especially for the low W and effective S of stratus. The increased competition reduces MD, re, and σ, which inhibit coalescence and thus reduce drizzle

  4. CALIPSO observations of near-cloud aerosol properties as a function of cloud fraction

    NASA Astrophysics Data System (ADS)

    Yang, Weidong; Marshak, Alexander; Várnai, Tamás.; Wood, Robert

    2014-12-01

    This paper uses spaceborne lidar data to study how near-cloud aerosol statistics of attenuated backscatter depend on cloud fraction. The results for a large region around the Azores show that (1) far-from-cloud aerosol statistics are dominated by samples from scenes with lower cloud fractions, while near-cloud aerosol statistics are dominated by samples from scenes with higher cloud fractions; (2) near-cloud enhancements of attenuated backscatter occur for any cloud fraction but are most pronounced for higher cloud fractions; (3) the difference in the enhancements for different cloud fractions is most significant within 5 km from clouds; (4) near-cloud enhancements can be well approximated by logarithmic functions of cloud fraction and distance to clouds. These findings demonstrate that if variability in cloud fraction across the scenes used for composite aerosol statistics is not considered, a sampling artifact will affect these statistics calculated as a function of distance to clouds. For the Azores region data set examined here, this artifact occurs mostly within 5 km from clouds and exaggerates the near-cloud enhancements of lidar backscatter and color ratio by about 30%. This shows that for accurate characterization of the changes in aerosol properties with distance to clouds, it is important to account for the impact of changes in cloud fraction.

  5. CALIPSO Observations of Near-Cloud Aerosol Properties as a Function of Cloud Fraction

    NASA Technical Reports Server (NTRS)

    Yang, Weidong; Marshak, Alexander; Varnai, Tamas; Wood, Robert

    2015-01-01

    This paper uses spaceborne lidar data to study how near-cloud aerosol statistics of attenuated backscatter depend on cloud fraction. The results for a large region around the Azores show that: (1) far-from-cloud aerosol statistics are dominated by samples from scenes with lower cloud fractions, while near-cloud aerosol statistics are dominated by samples from scenes with higher cloud fractions; (2) near-cloud enhancements of attenuated backscatter occur for any cloud fraction but are most pronounced for higher cloud fractions; (3) the difference in the enhancements for different cloud fractions is most significant within 5km from clouds; (4) near-cloud enhancements can be well approximated by logarithmic functions of cloud fraction and distance to clouds. These findings demonstrate that if variability in cloud fraction across the scenes used to composite aerosol statistics are not considered, a sampling artifact will affect these statistics calculated as a function of distance to clouds. For the Azores-region dataset examined here, this artifact occurs mostly within 5 km from clouds, and exaggerates the near-cloud enhancements of lidar backscatter and color ratio by about 30. This shows that for accurate characterization of the changes in aerosol properties with distance to clouds, it is important to account for the impact of changes in cloud fraction.

  6. [Multifractal cloud properties data assessment

    SciTech Connect

    Gautier, C.; Ricchiazzi, P.; Peterson, P.; Lavallee, D. ); Frouin, R.; Lubin, D. ); Lovejoy, S. ); Schertzer, D. )

    1992-05-06

    Our group has been very active over the last year, analyzing a number of data sets to characterize multifractal cloud properties and assess the effects of clouds on surface radiation properties (spectral and broadband). The data sets analyzed include: AVHRR observations of clouds over the ocean, SPOT observations of clouds over the ocean, SSM/I observations of clouds over the ocean, pyranometer data with all-sky photographs, pyrgeometer data all-sky photographs, and spectral surface irradiance all-sky photographs. A number of radiative transfer computations have been performed to help in the interpretation of these observations or provide theoretical guidance for their analysis. Finally 4 number of radiative transfer models have been acquired and tested to prepare for the interpretation of ARM/CART data.

  7. Measuring Cloud Properties from UAVs

    NASA Astrophysics Data System (ADS)

    Nicoll, K.; Harrison, R. G.; Roberts, G.

    2014-12-01

    Observations of in-situ cloud properties are an essential aspect of cloud microphysics studies. UAVs readily provide a platform from which high resolution cloud measurements can be made, both in the vertical and horizontal directions. Currently, however, one limiting factor in the use of UAVs for cloud studies is the lack of availability of lightweight, low power sensors. This work describes a number of small, disposable sensors for cloud droplet detection and electrical charge measurements, which have been flown on both free balloon and UAV platforms. The cloud droplet detector utilises optical reflection, combining a low power, high brightness LED as the optical source with a semiconductor photodiode as the detector. During daylight conditions, the photodiode detector also provides a measurement of broadband solar radiation, allowing an estimate of extinction within the cloud to be derived. The current consumption of the sensor is <30mA, and it has worked reliably in both day and night time conditions. Multiple flights of these sensors onboard UAVs with wingspan <2m (including Funjet and Easystar aircraft), made from southern France through a variety of cloud types will be presented.

  8. Death of an Arctic Mixed Phase Cloud: How Changes in the Arctic Environment Influence Cloud Properties and Cloud Radiative Feedbacks

    NASA Astrophysics Data System (ADS)

    Roesler, E. L.; Posselt, D. J.

    2012-12-01

    Arctic mixed phase stratocumulus clouds exert an important influence on the radiative budget over the Arctic ocean and sea ice. Field programs and numerical experiments have shown the properties of these clouds to be sensitive to changes in the surface properties, thermodynamic environment, and aerosols. While it is clear that Arctic mixed-phase clouds respond to changes in the Arctic environment, uncertainty remains as to how climate warming will affect the cloud micro- and macrophysical properties. This is in no small part due to the fact that there are nonlinear interactions between changes in atmospheric and surface properties and changes in cloud characteristics. In this study, large-eddy simulations are performed of an arctic mixed phase cloud observed during the Indirect and Semi-Direct Aerosol Campaign. A parameter-space-filling uncertainty quantification technique is used to rigorously explore how simulated arctic mixed phase clouds respond to changes in the properties of the environment. Specifically, the cloud ice and aerosol concentration, surface sensible and latent heat fluxes, and large scale temperature, water vapor, and vertical motion are systematically changed, and the properties of the resulting clouds are examined. It is found that Arctic mixed phase clouds exhibit four characteristic behaviors: stability, growth, decay, and dissipation. Sets of environmental and surface properties that lead to the emergence of each type of behavior are presented, and the implications for the response of Arctic clouds to changes in climate are explored.

  9. Cloud droplet nucleation and its connection to aerosol properties

    SciTech Connect

    Schwartz, S.E.

    1996-04-01

    Anthropogenic aerosols influence the earth`s radiation balance and climate directly, by scattering shortwave (solar) radiation in cloud-free conditions and indirectly, by increasing concentrations of cloud droplets thereby enhancing cloud shortwave reflectivity. These effects are thought to be significant in the context of changes in the earth radiation budget over the industrial period, exerting a radiative forcing that is of comparable magnitude to that of increased concentrations of greenhouse gases over this period but opposite in sign. However the magnitudes of both the direct and indirect aerosol effects are quite uncertain. Much of the uncertainty of the indirect effect arises from incomplete ability to describe changes in cloud properties arising from anthropogenic aerosols. This paper examines recent studies pertaining to the influence of anthropogenic aerosols on loading and properties of aerosols affecting their cloud nucleating properties and indicative of substantial anthropogenic influence on aerosol and cloud properties over the North Atlantic.

  10. Space shuttle exhaust cloud properties

    NASA Technical Reports Server (NTRS)

    Anderson, B. J.; Keller, V. W.

    1983-01-01

    A data base describing the properties of the exhaust cloud produced by the launch of the Space Transportation System and the acidic fallout observed after each of the first four launches was assembled from a series of ground and aircraft based measurements made during the launches of STS 2, 3, and 4. Additional data were obtained from ground-based measurements during firings of the 6.4 percent model of the Solid Rocket Booster at the Marshall Center. Analysis indicates that the acidic fallout is produced by atomization of the deluge water spray by the rocket exhaust on the pad followed by rapid scavening of hydrogen chloride gas aluminum oxide particles from the Solid Rocket Boosters. The atomized spray is carried aloft by updrafts created by the hot exhaust and deposited down wind. Aircraft measurements in the STS-3 ground cloud showed an insignificant number of ice nuclei. Although no measurements were made in the column cloud, the possibility of inadvertent weather modification caused by the interaction of ice nuclei with natural clouds appears remote.

  11. A CERES-like Cloud Property Climatology Using AVHRR Data

    NASA Astrophysics Data System (ADS)

    Minnis, P.; Bedka, K. M.; Yost, C. R.; Trepte, Q.; Bedka, S. T.; Sun-Mack, S.; Doelling, D.

    2015-12-01

    Clouds affect the climate system by modulating the radiation budget and distributing precipitation. Variations in cloud patterns and properties are expected to accompany changes in climate. The NASA Clouds and the Earth's Radiant Energy System (CERES) Project developed an end-to-end analysis system to measure broadband radiances from a radiometer and retrieve cloud properties from collocated high-resolution MODerate-resolution Imaging Spectroradiometer (MODIS) data to generate a long-term climate data record of clouds and clear-sky properties and top-of-atmosphere radiation budget. The first MODIS was not launched until 2000, so the current CERES record is only 15 years long at this point. The core of the algorithms used to retrieve the cloud properties from MODIS is based on the spectral complement of the Advanced Very High Resolution Radiometer (AVHRR), which has been aboard a string of satellites since 1978. The CERES cloud algorithms were adapted for application to AVHRR data and have been used to produce an ongoing CERES-like cloud property and surface temperature product that includes an initial narrowband-based radiation budget. This presentation will summarize this new product, which covers nearly 37 years, and its comparability with cloud parameters from CERES, CALIPSO, and other satellites. Examples of some applications of this dataset are given and the potential for generating a long-term radiation budget CDR is also discussed.

  12. Radiative properties of ice clouds

    SciTech Connect

    Mitchell, D.L.; Koracin, D.; Carter, E.

    1996-04-01

    A new treatment of cirrus cloud radiative properties has been developed, based on anomalous diffraction theory (ADT), which does not parameterize size distributions in terms of an effective radius. Rather, is uses the size distribution parameters directly, and explicitly considers the ice particle shapes. There are three fundamental features which characterize this treatment: (1) the ice path radiation experiences as it travels through an ice crystal is parameterized, (2) only determines the amount of radiation scattered and absorbed, and (3) as in other treatments, the projected area of the size distribution is conserved. The first two features are unique to this treatment, since it does not convert the ice particles into equivalent volume or area spheres in order to apply Mie theory.

  13. A Study to Investigate Cloud Feedback Processes and Evaluate GCM Cloud Variations Using Statistical Cloud Property Composites From ARM Data

    SciTech Connect

    George Tselioudis

    2009-08-11

    The representation of clouds in Global Climate Models (GCMs) remains a major source of uncertainty in climate change simulations. Cloud climatologies have been widely used to either evaluate climate model cloud fields or examine, in combination with other data sets, climate-scale relationships between cloud properties and dynamical or microphysical parameters. Major cloud climatologies have been based either on satellite observations of cloud properties or on surface observers views of cloud type and amount. Such data sets provide either the top-down view of column-integrated cloud properties (satellites) or the bottom-up view of the cloud field morphology (surface observers). Both satellite-based and surface cloud climatologies have been successfully used to examine cloud properties, to support process studies, and to evaluate climate and weather models. However, they also present certain limitations, since the satellite cloud types are defined using radiative cloud boundaries and surface observations are based on cloud boundaries visible to human observers. As a result, these data sets do not resolve the vertical distribution of cloud layers, an issue that is important in calculating both the radiative and the hydrologic effects of the cloud field. Ground-based cloud radar observations, on the other hand, resolve with good accuracy the vertical distribution of cloud layers and could be used to produce cloud type climatologies with vertical layering information. However, these observations provide point measurements only and it is not immediately clear to what extent they are representative of larger regimes. There are different methods that can be applied to minimize this problem and to produce cloud layering climatologies useful for both cloud process and model evaluation studies. If a radar system is run continuously over a number of years, it eventually samples a large number of dynamical and microphysical regimes. If additional data sets are used to put the

  14. Properties of aerosol processed by ice clouds

    NASA Astrophysics Data System (ADS)

    Rudich, Y.; Adler, G.; Moise, T.; Erlick-Haspel, C.

    2012-12-01

    We suggest that highly porous aerosol (HPA) can form in the upper troposphere/lower stratosphere when ice particles encounter sub-saturation leading to ice sublimation similar to freeze drying. This process can occur at the lower layers of cirrus clouds (few km), at anvils of high convective clouds and thunderstorms, in clouds forming in atmospheric gravitational waves, in contrails and in high convective clouds injecting to the stratosphere. A new experimental system that simulates freeze drying of proxies for atmospheric aerosol at atmospheric pressure was constructed and various proxies for atmospheric soluble aerosol were studied. The properties of resulting HPA were characterized by various methods. It was found that the resulting aerosol have larger sizes (extent depends on substance and mixing), lower density (largevoid fraction), lower optical extinction and higher CCN activity and IN activity. Implication of HPA's unique properties and their atmospheric consequences to aerosol processing in ice clouds and to cloud cycles will be discussed.

  15. 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.

  16. Modeling and parameterization of horizontally inhomogeneous cloud radiative properties

    NASA Technical Reports Server (NTRS)

    Welch, R. M.

    1995-01-01

    One of the fundamental difficulties in modeling cloud fields is the large variability of cloud optical properties (liquid water content, reflectance, emissivity). The stratocumulus and cirrus clouds, under special consideration for FIRE, exhibit spatial variability on scales of 1 km or less. While it is impractical to model individual cloud elements, the research direction is to model a statistical ensembles of cloud elements with mean-cloud properties specified. The major areas of this investigation are: (1) analysis of cloud field properties; (2) intercomparison of cloud radiative model results with satellite observations; (3) radiative parameterization of cloud fields; and (4) development of improved cloud classification algorithms.

  17. Global Analysis of Aerosol Properties Above Clouds

    NASA Technical Reports Server (NTRS)

    Waquet, F.; Peers, F.; Ducos, F.; Goloub, P.; Platnick, S. E.; Riedi, J.; Tanre, D.; Thieuleux, F.

    2013-01-01

    The seasonal and spatial varability of Aerosol Above Cloud (AAC) properties are derived from passive satellite data for the year 2008. A significant amount of aerosols are transported above liquid water clouds on the global scale. For particles in the fine mode (i.e., radius smaller than 0.3 m), including both clear sky and AAC retrievals increases the global mean aerosol optical thickness by 25(+/- 6%). The two main regions with man-made AAC are the tropical Southeast Atlantic, for biomass burning aerosols, and the North Pacific, mainly for pollutants. Man-made AAC are also detected over the Arctic during the spring. Mineral dust particles are detected above clouds within the so-called dust belt region (5-40 N). AAC may cause a warming effect and bias the retrieval of the cloud properties. This study will then help to better quantify the impacts of aerosols on clouds and climate.

  18. Global analysis of cloud field coverage and radiative properties, using morphological methods and MODIS observations

    NASA Astrophysics Data System (ADS)

    Bar-Or, R. Z.; Altaratz, O.; Koren, I.

    2011-01-01

    The recently recognized continuous transition zone between detectable clouds and cloud-free atmosphere ("the twilight zone") is affected by undetectable clouds and humidified aerosol. In this study, we suggest to distinguish cloud fields (including the detectable clouds and the surrounding twilight zone) from cloud-free areas, which are not affected by clouds. For this classification, a robust and simple-to-implement cloud field masking algorithm which uses only the spatial distribution of clouds, is presented in detail. A global analysis, estimating Earth's cloud field coverage (50° S-50° N) for 28 July 2008, using the Moderate Resolution Imaging Spectroradiometer (MODIS) data, finds that while the declared cloud fraction is 51%, the global cloud field coverage reaches 88%. The results reveal the low likelihood for finding a cloud-free pixel and suggest that this likelihood may decrease as the pixel size becomes larger. A global latitudinal analysis of cloud fields finds that unlike oceans, which are more uniformly covered by cloud fields, land areas located under the subsidence zones of the Hadley cell (the desert belts), contain proper areas for investigating cloud-free atmosphere as there is 40-80% probability to detect clear sky over them. Usually these golden-pixels, with higher likelihood to be free of clouds, are over deserts. Independent global statistical analysis, using MODIS aerosol and cloud products, reveals a sharp exponential decay of the global mean aerosol optical depth (AOD) as a function of the distance from the nearest detectable cloud, both above ocean and land. Similar statistical analysis finds an exponential growth of mean aerosol fine-mode fraction (FMF) over oceans when the distance from the nearest cloud increases. A 30 km scale break clearly appears in several analyses here, suggesting this is a typical natural scale of cloud fields. This work shows different microphysical and optical properties of cloud fields, urging to separately

  19. Global analysis of cloud field coverage and radiative properties, using morphological methods and MODIS observations

    NASA Astrophysics Data System (ADS)

    Bar-Or, R. Z.; Altaratz, O.; Koren, I.

    2010-08-01

    The recently recognized continuous transition zone between detectable clouds and cloud-free atmosphere ("the twilight zone") is affected by undetectable clouds and humidified aerosol. In this study, we suggest to distinguish cloud fields (including the detectable clouds and the surrounding twilight zone) from cloud-free areas, which are not affected by clouds. For this classification, a robust and simple-to-implement cloud field masking algorithm which uses only the spatial distribution of clouds, is presented in detail. A global analysis, estimating Earth's cloud field coverage (50° S-50° N) for 28 July 2008, using the Moderate Resolution Imaging Spectroradiometer (MODIS) data, finds that while the declared cloud fraction is 51%, the global cloud field coverage reaches 88%. The results reveal the low likelihood for finding a cloud free pixel and suggest that this likelihood may decrease as the pixel size becomes larger. A global latitudinal analysis of cloud fields finds that unlike oceans, which are more uniformly covered by cloud fields, land areas located under the subsidence zones of the Hadley cell (the desert belts), contain proper areas for investigating cloud free atmosphere as there is 40-80% probability to detect clear sky over them. Usually these golden-pixels, with higher likelihood to be free of clouds, are over deserts. Independent global statistical analysis, using MODIS aerosol and cloud products, reveals a sharp exponential decay of the global mean aerosol optical depth (AOD) as a function of the distance from the nearest detectable cloud, both above ocean and land. Similar statistical analysis finds an exponential growth of mean aerosol fine-mode fraction (FMF) over Oceans when the distance from the nearest cloud increases. A 30 km scale break clearly appears in several analyses here, suggesting this is a typical natural scale of cloud fields. This work shows different microphysical and optical properties of cloud fields, urging to separately

  20. Multi-Spectral Cloud Property Retrieval

    NASA Technical Reports Server (NTRS)

    Carlson, Barbara E.; Lynch, R

    1999-01-01

    Despite numerous studies to retrieve cloud properties using infrared measurements the information content of the data has not yet been fully exploited. In an effort to more fully utilize the information content of infrared measurements, we have developed a multi-spectral technique for retrieving effective cloud particle size, optical depth and effective cloud temperature. While applicable to all cloud types, we begin by validating our retrieval technique through analysis of MS spectral radiances obtained during the SUCCESS field campaign over the ARM SGP CART facility, and compare our retrieval product with lidar and MODIS Airborne Simulator (MAS) measurement results. The technique is then applied to the Nimbus-4 MS infrared spectral measurements to obtain global cloud information.

  1. Meteorological and aerosol effects on marine cloud microphysical properties

    NASA Astrophysics Data System (ADS)

    Sanchez, K. J.; Russell, L. M.; Modini, R. L.; Frossard, A. A.; Ahlm, L.; Corrigan, C. E.; Roberts, G. C.; Hawkins, L. N.; Schroder, J. C.; Bertram, A. K.; Zhao, R.; Lee, A. K. Y.; Lin, J. J.; Nenes, A.; Wang, Z.; Wonaschütz, A.; Sorooshian, A.; Noone, K. J.; Jonsson, H.; Toom, D.; Macdonald, A. M.; Leaitch, W. R.; Seinfeld, J. H.

    2016-04-01

    Meteorology and microphysics affect cloud formation, cloud droplet distributions, and shortwave reflectance. The Eastern Pacific Emitted Aerosol Cloud Experiment and the Stratocumulus Observations of Los-Angeles Emissions Derived Aerosol-Droplets studies provided measurements in six case studies of cloud thermodynamic properties, initial particle number distribution and composition, and cloud drop distribution. In this study, we use simulations from a chemical and microphysical aerosol-cloud parcel (ACP) model with explicit kinetic drop activation to reproduce observed cloud droplet distributions of the case studies. Four cases had subadiabatic lapse rates, resulting in fewer activated droplets, lower liquid water content, and higher cloud base height than an adiabatic lapse rate. A weighted ensemble of simulations that reflect measured variation in updraft velocity and cloud base height was used to reproduce observed droplet distributions. Simulations show that organic hygroscopicity in internally mixed cases causes small effects on cloud reflectivity (CR) (<0.01), except for cargo ship and smoke plumes, which increased CR by 0.02 and 0.07, respectively, owing to their high organic mass fraction. Organic hygroscopicity had larger effects on droplet concentrations for cases with higher aerosol concentrations near the critical diameter (namely, polluted cases with a modal peak near 0.1 µm). Differences in simulated droplet spectral widths (k) caused larger differences in CR than organic hygroscopicity in cases with organic mass fractions of 60% or less for the cases shown. Finally, simulations from a numerical parameterization of cloud droplet activation suitable for general circulation models compared well with the ACP model, except under high organic mass fraction.

  2. Ice cloud microphysical properties in tropical Pacific regions derived from CloudSat and CALIPSO measurements

    NASA Astrophysics Data System (ADS)

    Takahashi, Naoya; Hayasaka, Tadahiro; Okamoto, Hajime

    2017-02-01

    We revealed the difference in tropical ice cloud microphysical properties between the western Pacific (WP) and the eastern Pacific (EP), based on satellite retrievals. Vertical profile of effective particle radius of ice cloud (re) was estimated from active sensors on board CloudSat and CALIPSO satellites. In this study, we focused only on ice cloud which is defined as clouds with the cloud top temperature lower than 0°C. To investigate the relationship between cloud optical properties and cloud vertical structures, these ice clouds were classified into five types based on cloud optical thickness values. Compared the vertical profile of re in WP with that in the EP, re around the freezing level within convective cloud in EP slightly larger than that in WP. This analysis also shows that re of optically thick cloud is larger than that of optically thin cloud. The difference in re may be caused by differences in moisture convergence, upward motion, aerosols.

  3. Cumulus cloud properties derived using Landsat satellite data

    NASA Technical Reports Server (NTRS)

    Wielicki, B. A.; Welch, R. M.

    1986-01-01

    Landsat Multispectral Scanner (MSS) digital data are used to remotely sense cumulus cloud properties such as cloud fraction and cloud reflectance, along with the distribution of cloud number and cloud fraction as a function of cloud size. The analysis is carried out for four cumulus fields covering regions approximately 150 km square. Results for these initial cloud fields indicate that: (1) the common intuitive model of clouds as nearly uniform reflecting surfaces is a poor representation of cumulus clouds, (2) the cumulus clouds were often multicelled, even for clouds as small as 1 km in diameter, (3) cloud fractional coverage derived using a simple reflectance threshold is sensitive to the chosen threshold even for 57-meter resolution Landsat data, (4) the sensitivity of cloud fraction to changes in satellite sensor resolution is less sensitive than suggested theoretically, and (5) the Landsat derived cloud size distributions show encouraging similarities among the cloud fields examined.

  4. Satellite Determination of Stratus Cloud Microphysical Properties.

    NASA Astrophysics Data System (ADS)

    Zuidema, Paquita; Hartmann, Dennis L.

    1995-06-01

    Satellite measurements of liquid water path from SSM/I, broadband albedo from ERBE, and cloud characteristics from ISCCP are used to study stratus regions. An average cloud liquid water path of 0.120 ± 0.032 kg m2 is derived by dividing the average liquid water path for stratus areas by the fractional area coverage of cloud in the region. The diurnal range in this average cloud liquid water path is about 25%. Stratus cloud liquid water is positively correlated with cloud amount and is negatively correlated with low cloud-top temperature.Cloud liquid water path (LWP) and cloud albedo measurements are used to derive an effective droplet radius using the plane-parallel cloud albedo model of Slingo. The 2.5;dg by 2.5;dg grid boxes are first screened for completely overcast scenes in an attempt to justify the plane-parallel assumption. The mean effective droplet radius for this sample is 10.1 ± 4.4 m. This serves as an upper bound since small-scale LWP variability is estimated to affect the average albedo by up to 0.07, corresponding to an overestimate in the derived droplet size of up to almost 6 m. The authors find larger droplet sizes in the evening than in the morning, along with smaller LWPs and lower albedos. No correlation is seen between effective radius and liquid water path, reinforcing the independence of these two parameters. Small droplet sizes are only derived in conjunction with high albedos, but this may simply reflect the effect of LWP inhomogeneity on the albedo and hence the derived droplet size. Individual case studies both support the validity of the methodology given high spatial homogeneity and yet demonstrate the common occurrence of nonhomogeneous conditions within stratus regions.

  5. Satellite determination of stratus cloud microphysical properties

    SciTech Connect

    Zuidema, P.; Hartmann, D.L.

    1995-06-01

    Satellite measurements of liquid water path from SSM/I, broadband albedo from ERBE, and cloud characteristics from ISCCP are used to study stratus regions. An average cloud liquid water path of 0.120{+-}0.032 kg m{sup {minus}2} is derived by dividing the average liquid water path for stratus areas by the fractional area coverage of cloud in the region. The diurnal range in this average cloud liquid water path is about 25%. Stratus cloud liquid water is positively correlated with cloud amount and is negatively correlated with low cloud-top temperature. Cloud liquid water path (LWP) and cloud albedo measurements are used to derive an effective droplet radius using the plane-parallel cloud albedo model of Slingo. The 2.5{degrees} by 2.5{degrees} grid boxes are first screened for completely overcast scenes in an attempt to justify the plane-parallel assumption. The mean effective droplet radius for this sample is 10.1{+-}4.4{mu}m. This serves as an upper bound since small-scale LWP variability is estimated to affect the average albedo by up to 0.07, corresponding to an overestimate in the derived droplet size of up to almost 6{mu}m. The authors find larger droplet sizes in the evening than in the morning, along with smaller LWP`s and lower albedos. No correlation is seen between effective radius and liquid water path, reinforcing the independence of these two parameters. Small droplet sizes are only derived in conjunction with high albedos, but this may simply reflect the effect of LWP inhomogeneity on the albedo and hence the derived droplet size. Individual case studies both support the validity of the methodology given high spatial homogeneity and yet demonstrate the common occurrence of nonhomogeneous conditions within stratus regions. 63 refs., 18 figs., 3 tabs.

  6. Observations of Three-Dimensional Radiative Effects that Influence Satellite Retrievals of Cloud Properties

    NASA Technical Reports Server (NTRS)

    Varnai, Tamas; Marshak, Alexander; Lau, William K. M. (Technical Monitor)

    2001-01-01

    This paper examines three-dimensional (3D) radiative effects, which arise from horizontal radiative interactions between areas that have different cloud properties. Earlier studies have argued that these effects can cause significant uncertainties in current satellite retrievals of cloud properties, because the retrievals rely on one-dimensional (1D) theory and do not consider the effects of horizontal changes in cloud properties. This study addresses two questions: which retrieved cloud properties are influenced by 3D radiative effects, and where 3D effects tend to occur? The influence of 3D effects is detected from the wayside illumination and shadowing make clouds appear asymmetric: Areas appear brighter if the cloud top surface is tilted toward, rather than away from, the Sun. The analysis of 30 images by the Moderate Resolution Imaging Spectroradiometer (MODIS) reveals that retrievals of cloud optical thickness and cloud water content are most influenced by 3D effects, whereas retrievals of cloud particle size are much less affected. The results also indicate that while 3D effects are strongest at cloud edges, cloud top variability in cloud interiors, even in overcast regions, also produces considerable 3D effects. Finally, significant 3D effects are found in a wide variety of situations, ranging from thin clouds to thick ones and from low clouds to high ones.

  7. Characterisation of cloud properties from MAX-DOAS observations

    NASA Astrophysics Data System (ADS)

    Wagner, Thomas; Remmers, Julia; Beirle, Steffen; Dörner, Steffen; Shaiganfar, Reza; Ziegler, Marc

    2013-04-01

    Multi AXis (MAX-) DOAS observations observe the scattered sun light a various, mostly slant, elevation angles. From MAX-DOAS observations it is possible to retrieve the vertical column density of several important trace gases like NO2, HCHO, SO2, H2O, BrO, and also aerosol extinction. Usually, limited profile information for the lowest atmospheric layers (below about 5 km) can be obtained. Clouds strongly affect the atmospheric radiation transport. Thus they also have a strong effect on the interpretation of MAX-DOAS results. In many cases, especially for high clouds, it is still possible to retrieve reasonable trace gas and aerosol results in the presence of clouds. However, for low clouds and in particular for optically thick and vertically extended clouds, usually no meaningful MAX-DOAS retrievals are possible. Thus accurate information on cloud properties is crucial for the characterisation of the uncertainties of MAX-DOAS observations. In this study we investigate the suitability of several cloud-sensitive quantities, which can be retrieved from the MAX-DOAS observations themselves. Besides the measured radiance, we also analyse the so called colour index (intensity ratio at selected wavelengths), the absorption of the oxygen molecule (O2) and the oxygen dimer (O4) as well as the Ring effect. The effects of clouds on these quantities is investigated in detail and the respective results are related to cloud information based on sky images taken from ground and satellite. In addition also radiative transfer simulations are performed. As a main result of our studies we present recommendations for robust and effective cloud classification schemes based on MAX-DOAS observations.

  8. Southern Ocean Water Cloud Properties from Combined CALIOP, CloudSat and MODIS Measurements

    NASA Astrophysics Data System (ADS)

    Hu, Y.; ZENG, S.; Rodier, S. D.; Zhai, P.; Josset, D. B.; Liu, Z.; Lu, X.

    2013-12-01

    CALIOP, the dual wavelength, polarization sensitive lidar flying aboard the CALIPSO satellite, has been operating since June 2006 and is expected to continue for several more years. CALIOP provides accurate information about cloud top height and cloud thermodynamic phase information. Combining CALIOP measurements with collocated Cloudsat and MODIS measurements, we can estimate cloud properties such as 3-D structure of the clouds, cloud thermodynamic phase, cloud top extinction coefficient, cloud droplet number concentration (CDNC) and liquid water content (LWC) of water clouds. Cloud thermodynamics phase is derived from combined CALIOP and CloudSat measurements. Depolarization of backscatter by water clouds is due to multiple scattering, which depends strongly on cloud extinction coefficient. CDNC and LWC are derived from the CALIOP depolarization measurements and droplet size distribution information such as MODIS effective radius. The multi-instrument data analysis reviews unique properties of clouds in Southern oceans, e.g., frequent presence of supercooled liquid water clouds, large seasonal variations in water cloud droplet number concentrations (droplet number concentrations in summer is three times as large as winter time). We will present basic measurement concept and spatial/temporal statistics of these water cloud properties from measurements of the past seven years. We also attempt to assess seasonal and inter-annual variations of cloud microphysical properties using the past seven years' CALIPO/CloudSat measurements. CALIOP's depolarization ratio is one of the best calibrated measurements made by the A-Train sensors. Over the life of the CALIPSO mission, the stability of the CALIOP depolarization ratio calibration has remained within 1%. CALIOP's depolarization ratio measurements are used for studying changes in cloud thermodynamic phase and water cloud microphysical properties that are relevant to multiple scattering processes of water clouds

  9. PHYSICAL PROPERTIES OF COMPLEX C HALO CLOUDS

    SciTech Connect

    Hsu, W.-H.; Putman, M. E.; Peek, J. E. G.; Heitsch, F.; Clark, S. E.; Stanimirovic, S.

    2011-02-15

    Observations from the Galactic Arecibo L-band Feed Array H I (GALFA-H I) Survey of the tail of Complex C are presented and the halo clouds associated with this complex are cataloged. The properties of the Complex C clouds are compared to clouds cataloged at the tail of the Magellanic Stream to provide insight into the origin and destruction mechanism of Complex C. Magellanic Stream and Complex C clouds show similarities in their mass distributions (slope = -0.7 and -0.6 log (N( log (mass)))/ log (mass), respectively) and have a common line width of 20-30 km s{sup -1} (indicative of a warm component), which may indicate a common origin and/or physical process breaking down the clouds. The clouds cataloged at the tail of Complex C extend over a mass range of 10{sup 1.1}-10{sup 4.8} M{sub sun}, sizes of 10{sup 1.2}-10{sup 2.6} pc, and have a median volume density and pressure of 0.065 cm{sup -3} and (P/k) = 580 K cm{sup -3}. We do not see a prominent two-phase structure in Complex C, possibly due to its low metallicity and inefficient cooling compared to other halo clouds. Assuming that the Complex C clouds are in pressure equilibrium with a hot halo medium, we find a median halo density of 5.8 x 10{sup -4} cm{sup -3}, which given a constant distance of 10 kpc is at a z-height of {approx}3 kpc. Using the same argument for the Stream results in a median halo density of 8.4 x 10-{sup 5} (60 kpc/d) cm{sup -3}. These densities are consistent with previous observational constraints and cosmological simulations. We also assess the derived cloud and halo properties with three-dimensional grid simulations of halo H I clouds and find that the temperature is generally consistent within a factor of 1.5 and the volume densities, pressures, and halo densities are consistent within a factor of three.

  10. Implications of using transmitted vs. reflected light for determining cloud properties, cloud radiative effects and aerosol-cloud-interactions

    NASA Astrophysics Data System (ADS)

    LeBlanc, S. E.; Redemann, J.; Segal-Rosenhaimer, M.; Kacenelenbogen, M. S.; Shinozuka, Y.; Flynn, C. J.; Schmidt, S.; Pilewskie, P.; Song, S.; Woods, S.; Lawson, P.; Nenes, A.; Lin, J. J.; Ziemba, L. D.

    2015-12-01

    Light transmitted through clouds is sensitive to a different cloud volume than reflected light at cloud top. This difference in sampling volumes has implications when calculating the radiative effects of clouds (CRE) and aerosol-cloud-interactions (ACI). We present a comparison of retrieved cloud properties and the corresponding CRE and ACI based on transmitted and reflected light for a cloud sampled during the Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS, 2013) field campaign. Measurements of zenith radiances were obtained from the NASA DC-8 aircraft using the Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research (4STAR) instrument. 4STAR was deployed on an airborne platform during SEAC4RS alongside the Solar Spectral Flux Radiometer (SSFR). To retrieve cloud properties from transmitted shortwave radiation, we use a retrieval utilizing spectrally resolved measurements. Spectral features in shortwave radiation transmitted through clouds are sensitive to changes in cloud optical thickness, effective radius, and thermodynamic phase. The spectral features due to absorption and scattering processes by liquid water and ice cloud particles include shifts in spectral slopes, curvatures, maxima, and minima of cloud-transmitted radiance. These spectral features have been quantified by 15 parameters used to retrieve cloud properties from the 4STAR zenith radiances. Retrieved cloud optical thicknesses and effective radii based on transmitted shortwave radiation are compared to their counterparts obtained from reflected shortwave radiation measured above cloud with MODIS and with the enhanced MODIS Airborne Simulator (eMAS), the Research Scanning Polarimeter (RSP), and SSFR operating aboard the NASA ER-2 aircraft. Remotely sensed cloud particle effective radius are combined with in situ measurements of cloud and aerosol particles from the NASA Langley Aerosol Research Group Experiment (LARGE) CCN Counter

  11. Observation-based Understanding of the Cloud Properties over East China Region

    NASA Astrophysics Data System (ADS)

    Zhao, C.

    2015-12-01

    Cloud properties over East China are described based on observations from satellite (MODIS), ground site and aircraft. Based on satellite observations, 10-year averaged cloud fraction over the whole China region is around 66%, similar to the average value of global, with the largest cloud occurrence in Summer; the cloud fraction increases slightly during last 10 years; more clouds are found at southeast region than at northwest region; cloud droplet effective radius shows the smallest values around 10 um at mid-latitude regions and largest values at high latitude regions; further PDF analysis shows that cloud droplet effective radius demonstrates a bimodal distribution with maximum occurrences around 10-16 um. Ground site observations show that cloud fraction at Taihu site is around 65% for 2013, consistent with that found by MODIS at the closest grid to the site; more clouds are found at night than during day. In-situ aircraft observations over Huanghua city show that cloud droplet effective radius increases with height, with values from 3-5 um at low altitude, 7-9 um at mid altitude, to 10-13 um at high altitude. While the aircraft observation sample volume is limited, the in-situ observed cloud properties demonstrate that cloud droplet re increases with height, consistent with many findings by in-situ aircraft at other locations. The consistency of satellite observed cloud droplet re between East China and other regions is likely caused by the fact that the cloud properties observed by satellite is more representative of those clouds at high altitudes which are weakly affected by the aerosols within the boundary layers. On the other hand, the cloud droplet re at the cloud bases over East China is much smaller than those found at other locations, likely demonstrating the significant impacts by the heavy aerosol loadings at this region. Further studies with more site and aircraft observations over East China are needed.

  12. Microphysical properties of the Shuttle exhaust cloud

    NASA Technical Reports Server (NTRS)

    Keller, V. W.; Anderson, B. J.

    1983-01-01

    A data base describing the properties of the exhaust cloud produced by the launch of the STS has been developed based on data from a series of ground and aircraft based measurements made during the launches of STS 2, 3, and 4. Aircraft observations were performed during the STS-3 launch with a NOAA WP-3D Orion hurricane research aircraft which contained instrumentation for cloud condensation nucleus and ice nucleus counting, Aitken particle counting, and pH determination. Ground observations were conducted at 50 different sites, as well as in the direct exhaust from the solid rocket booster flame trench at all three launches. The data is analyzed in order to determine any possible adverse impacts of the exhaust products on human health and/or the environment. Analyses of the exhaust cloud measurements indicate that in the case of the ground cloud where plenty of large water drops are present and considerable scavenging and fallout of aerosol takes place, possible adverse impacts of the remaining aerosols (CCN and IN) on natural precipitation processes which may occur in the launch area hours after the launch are remote. However, it is determined that under certain atmospheric conditions there could be short term adverse effects on visibility.

  13. Overlap Properties of Clouds Generated by a Cloud Resolving Model

    NASA Technical Reports Server (NTRS)

    Oreopoulos, L.; Khairoutdinov, M.

    2002-01-01

    In order for General Circulation Models (GCMs), one of our most important tools to predict future climate, to correctly describe the propagation of solar and thermal radiation through the cloudy atmosphere a realistic description of the vertical distribution of cloud amount is needed. Actually, one needs not only the cloud amounts at different levels of the atmosphere, but also how these cloud amounts are related, in other words, how they overlap. Currently GCMs make some idealized assumptions about cloud overlap, for example that contiguous cloud layers overlap maximally and non-contiguous cloud layers overlap in a random fashion. Since there are difficulties in obtaining the vertical profile of cloud amount from observations, the realism of the overlap assumptions made in GCMs has not been yet rigorously investigated. Recently however, cloud observations from a relatively new type of ground radar have been used to examine the vertical distribution of cloudiness. These observations suggest that the GCM overlap assumptions are dubious. Our study uses cloud fields from sophisticated models dedicated to simulate cloud formation, maintenance, and dissipation called Cloud Resolving Models . These models are generally considered capable of producing realistic three-dimensional representation of cloudiness. Using numerous cloud fields produced by such a CRM we show that the degree of overlap between cloud layers is a function of their separation distance, and is in general described by a combination of the maximum and random overlap assumption, with random overlap dominating as separation distances increase. We show that it is possible to parameterize this behavior in a way that can eventually be incorporated in GCMs. Our results seem to have a significant resemblance to the results from the radar observations despite the completely different nature of the datasets. This consistency is encouraging and will promote development of new radiative transfer codes that will

  14. Multilayer cloud detection and retrieval of cloud physical and optical properties from thermal infrared measurements

    NASA Astrophysics Data System (ADS)

    Iwabuchi, H.; Tokoro, Y.; Saito, M.; Putri, N. S.; Katagiri, S.; Sekiguchi, M.

    2015-12-01

    Recent studies using active remote sensing have revealed significant occurrence of multi-layer cloud. Detection of multi-layer cloud is important in passive remote sensing for quality assessment of cloud property retrieval and identification of uncertain retrievals. An algorithm using several thermal infrared (TIR) bands at 6-13.5 micron wavelengths to detect multilayer cloud and retrieve cloud physical and optical properties including cloud thermodynamic phase is developed. This significantly extends applicability of passive remote sensing and improves accuracy of cloud property retrieval. The method uses the split window bands as well as the carbon dioxide and water vapor absorption bands. The forward model uses the two-stream approximation to solve radiative transfer with gaseous absorption treated by the correlated-k distribution method. Brightness temperature errors are evaluated by model-to-model and model-to-measurement comparisons. Top pressure of lower cloud in multi-layer cloud column can be retrieved if the upper cloud optical thickness is less than 6. The optimal estimation method is used to simultaneously infer several cloud properties including water path, effective particle radius and cloud-top pressure. The method is applied to the Moderate Resolution Imaging Spectroradiometer (MODIS) using 10 TIR bands and compared to MODIS operational product and active remote sensing measurements, showing promising results. The TIR method well detects optically thin clouds and retrieve their properties with relatively high accuracy. Particularly, cloud-top of optically thin cloud is estimated well. Multi-layer cloud detection works usually, while the TIR measurements miss very thin cloud that appears near the tropopause. The algorithm will be applied to frequent observation data from a new Japanese geostationary satellite, Himawari-8.

  15. Meteorological and Aerosol effects on Marine Cloud Microphysical Properties

    NASA Astrophysics Data System (ADS)

    Sanchez, K. J.; Russell, L. M.; Modini, R. L.; Frossard, A. A.; Ahlm, L.; Roberts, G.; Hawkins, L. N.; Schroder, J. C.; Wang, Z.; Lee, A.; Abbatt, J.; Lin, J.; Nenes, A.; Wonaschuetz, A.; Sorooshian, A.; Noone, K.; Jonsson, H.; Albrecht, B. A.; Desiree, T. S.; Macdonald, A. M.; Seinfeld, J.; Zhao, R.

    2015-12-01

    Both meteorology and microphysics affect cloud formation and consequently their droplet distributions and shortwave reflectance. The Eastern Pacific Emitted Aerosol Cloud Experiment (EPEACE) and the Stratocumulus Observations of Los-Angeles Emissions Derived Aerosol-Droplets (SOLEDAD) studies provide detailed measurements in 6 case studies of both cloud thermodynamic properties and initial particle number distribution and composition, as well as the resulting cloud drop distribution and composition. This study uses simulations of a detailed chemical and microphysical aerosol-cloud parcel (ACP) model with explicit kinetic drop activation to reproduce the observed cloud droplet distribution and composition. Four of the cases examined had a sub-adiabatic lapse rate, which was shown to have fewer droplets due to decreased maximum supersaturation, lower LWC and higher cloud base height, consistent with previous findings. These detailed case studies provided measured thermodynamics and microphysics that constrained the simulated droplet size distribution sufficiently to match the droplet number within 6% and the size within 19% for 4 of the 6 cases, demonstrating "closure" or consistency of the measured composition with the measured CCN spectra and the inferred and modeled supersaturation. The contribution of organic components to droplet formation shows small effects on the droplet number and size in the 4 marine cases that had background aerosol conditions with varying amounts of coastal, ship or other non-biogenic sources. In contrast, the organic fraction and hygroscopicity increased the droplet number and size in the cases with generated smoke and cargo ship plumes that were freshly emitted and not yet internally mixed with the background particles. The simulation results show organic hygroscopicity causes small effects on cloud reflectivity (<0.7%) with the exception of the cargo ship plume and smoke plume which increased absolute cloud reflectivity fraction by 0

  16. Estimating cirrus cloud properties from MIPAS data

    NASA Astrophysics Data System (ADS)

    Mendrok, J.; Schreier, F.; Höpfner, M.

    2007-04-01

    High resolution mid-infrared limb emission spectra observed by the spaceborne Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) showing evidence of cloud interference are analyzed. Using the new line-by-line multiple scattering [Approximate] Spherical Atmospheric Radiative Transfer code (SARTre), a sensitivity study with respect to cirrus cloud parameters, e.g., optical thickness and particle size distribution, is performed. Cirrus properties are estimated by fitting spectra in three distinct microwindows between 8 and 12 μm. For a cirrus with extremely low ice water path (IWP = 0.1 g/m2) and small effective particle size (D e = 10 μm) simulated spectra are in close agreement with observations in broadband signal and fine structures. We show that a multi-microwindow technique enhances reliability of MIPAS cirrus retrievals compared to single microwindow methods.

  17. Progress in Understanding the Impacts of 3-D Cloud Structure on MODIS Cloud Property Retrievals for Marine Boundary Layer Clouds

    NASA Technical Reports Server (NTRS)

    Zhang, Zhibo; Werner, Frank; Miller, Daniel; Platnick, Steven; Ackerman, Andrew; DiGirolamo, Larry; Meyer, Kerry; Marshak, Alexander; Wind, Galina; Zhao, Guangyu

    2016-01-01

    Theory: A novel framework based on 2-D Tayler expansion for quantifying the uncertainty in MODIS retrievals caused by sub-pixel reflectance inhomogeneity. (Zhang et al. 2016). How cloud vertical structure influences MODIS LWP retrievals. (Miller et al. 2016). Observation: Analysis of failed MODIS cloud property retrievals. (Cho et al. 2015). Cloud property retrievals from 15m resolution ASTER observations. (Werner et al. 2016). Modeling: LES-Satellite observation simulator (Zhang et al. 2012, Miller et al. 2016).

  18. Cloud Property Retrieval Products for Graciosa Island, Azores

    DOE Data Explorer

    Dong, Xiquan

    2014-05-05

    The motivation for developing this product was to use the Dong et al. 1998 method to retrieve cloud microphysical properties, such as cloud droplet effective radius, cloud droplets number concentration, and optical thickness. These retrieved properties have been used to validate the satellite retrieval, and evaluate the climate simulations and reanalyses. We had been using this method to retrieve cloud microphysical properties over ARM SGP and NSA sites. We also modified the method for the AMF at Shouxian, China and some IOPs, e.g. ARM IOP at SGP in March, 2000. The ARSCL data from ARM data archive over the SGP and NSA have been used to determine the cloud boundary and cloud phase. For these ARM permanent sites, the ARSCL data was developed based on MMCR measurements, however, there were no data available at the Azores field campaign. We followed the steps to generate this derived product and also include the MPLCMASK cloud retrievals to determine the most accurate cloud boundaries, including the thin cirrus clouds that WACR may under-detect. We use these as input to retrieve the cloud microphysical properties. Due to the different temporal resolutions of the derived cloud boundary heights product and the cloud properties product, we submit them as two separate netcdf files.

  19. Galactic cold cores. III. General cloud properties

    NASA Astrophysics Data System (ADS)

    Juvela, M.; Ristorcelli, I.; Pagani, L.; Doi, Y.; Pelkonen, V.-M.; Marshall, D. J.; Bernard, J.-P.; Falgarone, E.; Malinen, J.; Marton, G.; McGehee, P.; Montier, L. A.; Motte, F.; Paladini, R.; Tóth, L. V.; Ysard, N.; Zahorecz, S.; Zavagno, A.

    2012-05-01

    Context. In the project galactic cold cores we are carrying out Herschel photometric observations of cold regions of the interstellar clouds as previously identified with the Planck satellite. The aim of the project is to derive the physical properties of the population of cold clumps and to study its connection to ongoing and future star formation. Aims: We examine the cloud structure around the Planck detections in 71 fields observed with the Herschel SPIRE instrument by the summer of 2011. We wish to determine the general physical characteristics of the fields and to examine the morphology of the clouds where the cold high column density clumps are found. Methods: Using the Herschel SPIRE data, we derive colour temperature and column density maps of the fields. Together with ancillary data, we examine the infrared spectral energy distributions of the main clumps. The clouds are categorised according to their large scale morphology. With the help of recently released WISE satellite data, we look for signs of enhanced mid-infrared scattering ("coreshine"), an indication of growth of the dust grains, and have a first look at the star formation activity associated with the cold clumps. Results: The mapped clouds have distances ranging from ~100 pc to several kiloparsecs and cover a range of sizes and masses from cores of less than 10 M⊙ to clouds with masses in excess of 10 000 M⊙. Most fields contain some filamentary structures and in about half of the cases a filament or a few filaments dominate the morphology. In one case out of ten, the clouds show a cometary shape or have sharp boundaries indicative of compression by an external force. The width of the filaments is typically ~0.2-0.3 pc. However, there is significant variation from 0.1 pc to 1 pc and the estimates are sensitive to the methods used and the very definition of a filament. Enhanced mid-infrared scattering, coreshine, was detected in four clouds with six additional tentative detections. The

  20. Clouds vertical properties over the Northern Hemisphere monsoon regions from CloudSat-CALIPSO measurements

    NASA Astrophysics Data System (ADS)

    Das, Subrata Kumar; Golhait, R. B.; Uma, K. N.

    2017-01-01

    The CloudSat spaceborne radar and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) space-borne lidar measurements, provide opportunities to understand the intriguing behavior of the vertical structure of monsoon clouds. The combined CloudSat-CALIPSO data products have been used for the summer season (June-August) of 2006-2010 to present the statistics of cloud macrophysical (such as cloud occurrence frequency, distribution of cloud top and base heights, geometrical thickness and cloud types base on occurrence height), and microphysical (such as ice water content, ice water path, and ice effective radius) properties of the Northern Hemisphere (NH) monsoon region. The monsoon regions considered in this work are the North American (NAM), North African (NAF), Indian (IND), East Asian (EAS), and Western North Pacific (WNP). The total cloud fraction over the IND (mostly multiple-layered cloud) appeared to be more frequent as compared to the other monsoon regions. Three distinctive modes of cloud top height distribution are observed over all the monsoon regions. The high-level cloud fraction is comparatively high over the WNP and IND. The ice water content and ice water path over the IND are maximum compared to the other monsoon regions. We found that the ice water content has little variations over the NAM, NAF, IND, and WNP as compared to their macrophysical properties and thus give an impression that the regional differences in dynamics and thermodynamics properties primarily cause changes in the cloud frequency or coverage and only secondary in the cloud ice properties. The background atmospheric dynamics using wind and relative humidity from the ERA-Interim reanalysis data have also been investigated which helps in understanding the variability of the cloud properties over the different monsoon regions.

  1. Effects of cloud optical property feedbacks on the greenhouse warming

    SciTech Connect

    Molnar, G. ); Wang, Weichyung )

    1992-08-01

    Cloud optical properties, in particular the optical thickness [tau] affect the earth-atmosphere radiation budget, and their potential changes associated with climate changes may induce feedback effect. A one-dimensional radiative-convective model was used to illustrate that the difference in the vertical distribution of the radiative forcing between CO[sub 2] increase and changes of solar constant can result in a different [tau] feedback. A general circulation model, done by Wang et al., indicates that these trace gases provide an important radiative energy source for the present climate. Because the radiative-forcing behavior of CO[sub 2] is different from that of these other gases, the simulations also show that different radiative forcing can lead to quite different climatic effects. A one-dimensional model is used to investigate the [tau] feedback associated with trace gases. Because of the different changes in the [tau] vertical distributions, the [tau] feedback is calculated to be a small negative value for a CO[sub 2] increase, larger negative values for increases of trace gases, and the strongest negative feedback for CFCS. Similar experiments were also conducted using a revised version of the Somerville and Remer [tau] scheme. The results indicate that the negative feedback for CO[sub 2] increases for a single cloud layer becomes much smaller when multiple-layer clouds are used. Because this scheme assumes a strong functional dependence of the local temperature, the [tau] feedback is also found to be sensitive to model dimensionality. In addition, the strength of the [tau] feedback calculated from both schemes depend on the vertical distribution of cloud cover for the control climate, indicating the complexity of cloud-radiation interactions. Clearly, more observational and theoretical studies are needed to understand the cloud microphysics and their relation to large-scale climate variables.

  2. Overview of the CERES Edition-4 Multilayer Cloud Property Datasets

    NASA Astrophysics Data System (ADS)

    Chang, F. L.; Minnis, P.; Sun-Mack, S.; Chen, Y.; Smith, R. A.; Brown, R. R.

    2014-12-01

    Knowledge of the cloud vertical distribution is important for understanding the role of clouds on earth's radiation budget and climate change. Since high-level cirrus clouds with low emission temperatures and small optical depths can provide a positive feedback to a climate system and low-level stratus clouds with high emission temperatures and large optical depths can provide a negative feedback effect, the retrieval of multilayer cloud properties using satellite observations, like Terra and Aqua MODIS, is critically important for a variety of cloud and climate applications. For the objective of the Clouds and the Earth's Radiant Energy System (CERES), new algorithms have been developed using Terra and Aqua MODIS data to allow separate retrievals of cirrus and stratus cloud properties when the two dominant cloud types are simultaneously present in a multilayer system. In this paper, we will present an overview of the new CERES Edition-4 multilayer cloud property datasets derived from Terra as well as Aqua. Assessment of the new CERES multilayer cloud datasets will include high-level cirrus and low-level stratus cloud heights, pressures, and temperatures as well as their optical depths, emissivities, and microphysical properties.

  3. Validation of Cloud Properties From Multiple Satellites Using CALIOP Data

    NASA Technical Reports Server (NTRS)

    Yost, Christopher R.; Minnis, Patrick; Bedka, Kristopher M.; Heck, Patrick W.; Palikonda, Rabindra; Sun-Mack, Sunny; Trepte, Qing

    2016-01-01

    The NASA Langley Satellite ClOud and Radiative Property retrieval System (SatCORPS) is routinely applied to multispectral imagery from several geostationary and polar-orbiting imagers to retrieve cloud properties for weather and climate applications. Validation of the retrievals with independent datasets is continuously ongoing in order to understand differences caused by calibration, spatial resolution, viewing geometry, and other factors. The CALIOP instrument provides a decade of detailed cloud observations which can be used to evaluate passive imager retrievals of cloud boundaries, thermodynamic phase, cloud optical depth, and water path on a global scale. This paper focuses on comparisons of CALIOP retrievals to retrievals from MODIS, VIIRS, AVHRR, GOES, SEVIRI, and MTSAT. CALIOP is particularly skilled at detecting weakly-scattering cirrus clouds with optical depths less than approx. 0.5. These clouds are often undetected by passive imagers and the effect this has on the property retrievals is discussed.

  4. Study of the Radiative Properties of Inhomogeneous Stratocumulus Clouds

    NASA Technical Reports Server (NTRS)

    Batey, Michael

    1996-01-01

    Clouds play an important role in the radiation budget of the atmosphere. A good understanding of how clouds interact with solar radiation is necessary when considering their effects in both general circulation models and climate models. This study examined the radiative properties of clouds in both an inhomogeneous cloud system, and a simplified cloud system through the use of a Monte Carlo model. The purpose was to become more familiar with the radiative properties of clouds, especially absorption, and to investigate the excess absorption of solar radiation from observations over that calculated from theory. The first cloud system indicated that the absorptance actually decreased as the cloud's inhomogeneity increased, and that cloud forcing does not indicate any changes. The simplified cloud system looked at two different cases of absorption of solar radiation in the cloud. The absorptances calculated from the Monte Carlo is compared to a correction method for calculating absorptances and found that the method can over or underestimate absorptances at cloud edges. Also the cloud edge effects due to solar radiation points to a possibility of overestimating the retrieved optical depth at the edge, and indicates a possible way to correct for it. The effective cloud fraction (Ne) for a long time has been calculated from a cloud's reflectance. From the reflectance it has been observed that the N, for most cloud geometries is greater than the actual cloud fraction (Nc) making a cloud appear wider than it is optically. Recent studies we have performed used a Monte Carlo model to calculate the N, of a cloud using not only the reflectance but also the absorptance. The derived Ne's from the absorptance in some of the Monte Carlo runs did not give the same results as derived from the reflectance. This study also examined the inhomogeneity of clouds to find a relationship between larger and smaller scales, or wavelengths, of the cloud. Both Fourier transforms and wavelet

  5. MAGIC Cloud Properties from Zenith Radiance Data Final Campaign Summary

    SciTech Connect

    Chiu, J. -Y.C.; Gregory, L.; Wagener, R.

    2016-01-01

    Cloud droplet size and optical depth are the most fundamental properties for understanding cloud formation, dissipation and interactions with aerosol and drizzle. They are also a crucial determinant of Earth’s radiative and water-energy balances. However, these properties are poorly predicted in climate models. As a result, the response of clouds to climate change is one of the major sources of uncertainty in climate prediction.

  6. Cloud properties inferred from 8-12 micron data

    NASA Technical Reports Server (NTRS)

    Strabala, Kathleen I.; Ackerman, Steven A.; Menzel, W. Paul

    1994-01-01

    A trispectral combination of observations at 8-, 11-, and 12-micron bands is suggested for detecting cloud and cloud properties in the infrared. Atmospheric ice and water vapor absorption peak in opposite halves of the window region so that positive 8-minus-11-micron brightness temperature differences indicate cloud, while near-zero or negative differences indicate clear regions. The absorption coefficient for water increases more between 11 and 12 microns than between 8 and 11 microns, while for ice, the reverse is true. Cloud phases is determined by a scatter diagram of 8-minus-11-micron versus 11-minus-12-micron brightness temperature differences; ice cloud shows a slope greater than 1 and water cloud less than 1. The trispectral brightness temperature method was tested upon high-resolution interferometer data resulting in clear-cloud and cloud-phase delineation. Simulations using differing 8-micron bandwidths revealed no significant degradation of cloud property detection. Thus, the 8-micron bandwidth for future satellites can be selected based on the requirements of other applications, such as surface characterization studies. Application of the technique to current polar-orbiting High-Resolution Infrared Sounder (HIRS)-Advanced Very High Resolution Radiometer (AVHRR) datasets is constrained by the nonuniformity of the cloud scenes sensed within the large HIRS field of view. Analysis of MAS (MODIS Airborne Simulator) high-spatial resolution (500 m) data with all three 8-, 11-, and 12-micron bands revealed sharp delineation of differing cloud and background scenes, from which a simple automated threshold technique was developed. Cloud phase, clear-sky, and qualitative differences in cloud emissivity and cloud height were identified on a case study segment from 24 November 1991, consistent with the scene. More rigorous techniques would allow further cloud parameter clarification. The opportunities for global cloud delineation with the Moderate-Resolution Imaging

  7. Impact of Anthropogenic Aerosol on the Properties of Shallow Maritime Cumulus Clouds

    NASA Astrophysics Data System (ADS)

    Gao, L.; Wilcox, E. M.; Shan, Y.

    2015-12-01

    The northern Indian Ocean region is frequently covered by cumulus clouds that are responsible for moistening the boundary layer and contribute to tropical deep convection. Because this region is uniquely located close to the highly polluted Indian plateau, air mass with high aerosol concentration can be easily transported to this area. These small cumulus clouds, coupled with the effects of aerosol, have a large potential to affect the regional and global albedo. The aerosol effects on cloud properties and atmospheric structures are examined in this work, using the UAV (Unmanned Aerial Vehicle) data that are observed from CARDEX (Cloud, Aerosol, Radiative forcing, Dynamics EXperiment) and MAC (Maldives Autonomous unmanned aerial vehicle Campaign). On average, the high polluted cases show warmer temperature through the entire atmospheric column and higher relative humidity in boundary layer. The maximum temperature difference between high and low polluted cases can be found around the cloud layer altitude. In addition, the height of sub-cloud mixed layer is higher in low polluted cases. Clouds in high polluted cases are generally becoming narrower and taller than those in low polluted cases, and are associated with greater cloud water content and higher cloud droplet number concentrations, especially in small droplet range (diameters less than 10 micrometers). Meanwhile, the effective radius of cloud droplets decreases as the aerosol concentration increases. These facts indicate that the high polluted clouds are on average brighter with higher albedo.

  8. 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.

  9. The clouds of Venus. [physical and chemical properties

    NASA Technical Reports Server (NTRS)

    Young, A. T.

    1975-01-01

    The physical and chemical properties of the clouds of Venus are reviewed, with special emphasis on data that are related to cloud dynamics. None of the currently-popular interpretations of cloud phenomena on Venus is consistent with all the data. Either a considerable fraction of the observational evidence is faulty or has been misinterpreted, or the clouds of Venus are much more complex than the current simplistic models. Several lines of attack are suggested to resolve some of the contradictions. A sound understanding of the clouds appears to be several years in the future.

  10. Some Technical Aspects of a CALIOP and MODIS Data Analysis that Examines Near-Cloud Aerosol Properties as a Function of Cloud Fraction

    NASA Technical Reports Server (NTRS)

    Varnai, Tamas; Yang, Weidong; Marshak, Alexander

    2016-01-01

    CALIOP shows stronger near-cloud changes in aerosol properties at higher cloud fractions. Cloud fraction variations explain a third of near-cloud changes in overall aerosol statistics. Cloud fraction and aerosol particle size distribution have a complex relationship.

  11. Long Term Cloud Property Datasets From MODIS and AVHRR Using the CERES Cloud Algorithm

    NASA Technical Reports Server (NTRS)

    Minnis, Patrick; Bedka, Kristopher M.; Doelling, David R.; Sun-Mack, Sunny; Yost, Christopher R.; Trepte, Qing Z.; Bedka, Sarah T.; Palikonda, Rabindra; Scarino, Benjamin R.; Chen, Yan; Hong, Gang; Bhatt, Rajendra

    2015-01-01

    Cloud properties play a critical role in climate change. Monitoring cloud properties over long time periods is needed to detect changes and to validate and constrain models. The Clouds and the Earth's Radiant Energy System (CERES) project has developed several cloud datasets from Aqua and Terra MODIS data to better interpret broadband radiation measurements and improve understanding of the role of clouds in the radiation budget. The algorithms applied to MODIS data have been adapted to utilize various combinations of channels on the Advanced Very High Resolution Radiometer (AVHRR) on the long-term time series of NOAA and MetOp satellites to provide a new cloud climate data record. These datasets can be useful for a variety of studies. This paper presents results of the MODIS and AVHRR analyses covering the period from 1980-2014. Validation and comparisons with other datasets are also given.

  12. Using SEVIRI radiances to retrieve cloud optical properties of convective cloud systems

    NASA Astrophysics Data System (ADS)

    Müller, Jennifer; Fischer, Jürgen; Hünerbein, Anja; Deneke, Hartwig; Macke, Andreas

    2013-05-01

    In this case study the development of cloud properties (cloud optical depth, effective radius and cloud top height) during the life-cycle of a convective cloud system over Europe was analyzed. To retrieve the properties we developed a retrieval scheme based on the radiative transfer code MOMO and an optimal estimation procedure. Input data are the visible to short-wavelength infrared channels from SEVIRI. In contrast to many other retrieval schemes we used 4 channels simultaneously. Especially the 3,9μm channel provides additional information due to the fact that it measures solar reflectance and thermal emission and allows the inclusion of cloud top height into the retrieval. By using a time series of SEVIRI measurements we want to provide and examine the microphysical development of the cloud over life-time. We monitored the growth of the system and found the most active parts of the convection with the highest water content and optical depth in those regions where the cloud top height is largest, too. The effective radius of the cloud particles is largest in older regions of the cloud system, where the cloud is already decaying.

  13. Cloud properties and associated radiative heating rates in the tropical western Pacific

    SciTech Connect

    Mather, Jim H.; McFarlane, Sally A.; Miller, Mark A.; Johnson, Karen L.

    2007-03-01

    Radiative heating of the atmosphere affects cloud evolution on the cloud scale and it influences large-scale vertical motion. Obtaining good estimates of radiative heating rate profiles has been difficult due to a lack of cloud profile observations. The Atmospheric Radiation Measurement (ARM) program has been measuring cloud property distributions at sites around the globe including three in the tropical western Pacific (TWP) region. We have analyzed a month of these remote sensing observations at Manus and Nauru to calculate time series of vertical cloud property profiles and radiative heating rates. This data set will be an important tool for describing radiative processes in the tropics and assessing the simulation of these processes in dynamical models.

  14. Cloud Properties and Radiative Heating Rates for TWP

    DOE Data Explorer

    Comstock, Jennifer

    2013-11-07

    A cloud properties and radiative heating rates dataset is presented where cloud properties retrieved using lidar and radar observations are input into a radiative transfer model to compute radiative fluxes and heating rates at three ARM sites located in the Tropical Western Pacific (TWP) region. The cloud properties retrieval is a conditional retrieval that applies various retrieval techniques depending on the available data, that is if lidar, radar or both instruments detect cloud. This Combined Remote Sensor Retrieval Algorithm (CombRet) produces vertical profiles of liquid or ice water content (LWC or IWC), droplet effective radius (re), ice crystal generalized effective size (Dge), cloud phase, and cloud boundaries. The algorithm was compared with 3 other independent algorithms to help estimate the uncertainty in the cloud properties, fluxes, and heating rates (Comstock et al. 2013). The dataset is provided at 2 min temporal and 90 m vertical resolution. The current dataset is applied to time periods when the MMCR (Millimeter Cloud Radar) version of the ARSCL (Active Remotely-Sensed Cloud Locations) Value Added Product (VAP) is available. The MERGESONDE VAP is utilized where temperature and humidity profiles are required. Future additions to this dataset will utilize the new KAZR instrument and its associated VAPs.

  15. A Diversity of Dust Properties in Oort Cloud Comets

    NASA Astrophysics Data System (ADS)

    Kelley, Michael S.; Woodward, Charles E.; Harker, David Emerson; Wooden, Diane H.; Sitko, Michael L.; Russell, Ray W.; Kim, Daryl L.

    2015-01-01

    Comets are near-pristine relics from our Solar System's epoch of planet formation. Thus, the properties of comets can be used to infer the environment in which they formed and to compare our Solar System to disks observed around other stars today. Specifically, the dust in comets is a record of the high temperature processes that occurred in the inner disk, and the large scale mixing that transported dust from the hot inner disk to the cold comet formation zones. However, comet dust may not be wholly pristine, as radiation from the Galatic environment likely process the surfaces of Oort cloud comets. Mid-infrared spectroscopy is sensitive to the dust properties of comets. We present a summary of Oort cloud comets observed in the mid-infrared, and discuss their inferred dust properties. Targets include recent comets C/2009 P1 (Garradd), C/2011 L4 (PanSTARRS), C/2012 F6 (Lemmon), and C/2012 K1 (PanSTARRS). A wide range of spectra are seen, and we discuss the possibility that irradiated mantles on dynamically new comets affect their observed infrared spectra.This research is supported by NASA Planetary Astronomy Program award NNX13AH67G. This work is also supported at The Aerospace Corporation by the Independent Research and Development program.

  16. Impact of Cloud Model Microphysics on Passive Microwave Retrievals of Cloud Properties. Part I: Model Comparison Using EOF Analyses

    NASA Astrophysics Data System (ADS)

    Biggerstaff, Michael I.; Seo, Eun-Kyoung; Hristova-Veleva, Svetla M.; Kim, Kwang-Yul

    2006-07-01

    The impact of model microphysics on the relationships among hydrometeor profiles, latent heating, and derived satellite microwave brightness temperatures TB have been examined using a nonhydrostatic, adaptive-grid cloud model to simulate a mesoscale convective system over water. Two microphysical schemes (each employing three-ice bulk parameterizations) were tested for two different assumptions in the number of ice crystals assumed to be activated at 0°C to produce simulations with differing amounts of supercooled cloud water. The model output was examined using empirical orthogonal function (EOF) analysis, which provided a quantitative framework in which to compare the simulations. Differences in the structure of the vertical anomaly patterns were related to physical processes and attributed to different approaches in cloud microphysical parameterizations in the two schemes. Correlations between the first EOF coefficients of cloud properties and TB at frequencies associated with the Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) showed additional differences between the two parameterization schemes that affected the relationship between hydrometeors and TB. Classified in terms of TB, the microphysical schemes produced significantly different mean vertical profiles of cloud water, cloud ice, snow, vertical velocity, and latent heating. The impact of supercooled cloud water on the 85-GHz TB led to a 15% variation in mean convective rain mass at the surface. The variability in mean profiles produced by the four simulations indicates that the retrievals of cloud properties, especially latent heating, based on TMI frequencies are dependent on the particular microphysical parameterizations used to construct the retrieval database.

  17. Radiative Effect of Clouds on Tropospheric Chemistry: Sensitivity to Cloud Vertical Distributions and Optical Properties

    NASA Astrophysics Data System (ADS)

    Liu, H.; Crawford, J. H.; Pierce, R. B.; Considine, D. B.; Logan, J. A.; Duncan, B. N.; Norris, P.; Platnick, S. E.; Chen, G.; Yantosca, R. M.; Evans, M. J.

    2005-12-01

    Representation of clouds in global models poses a significant challenge since most cloud processes occur on sub-grid scales and must be parameterized. Uncertainties in cloud distributions and optical properties are therefore a limiting factor in model assessments of the radiative effect of clouds on global tropospheric chemistry. We present an analysis of the sensitivity of the radiative effect of clouds to cloud vertical distributions and optical properties with the use of the GEOS-CHEM global 3-D chemistry transport model coupled with the Fast-J radiative transfer algorithm. GEOS-CHEM was driven with a series of meteorological archives (GEOS1-STRAT, GEOS-3, and GEOS-4) generated by the Goddard Earth Observing System data assimilation system (GEOS DAS) at the NASA global Modeling and Assimilation Office (GMAO), which have significantly different cloud optical depths and vertical distributions. The column cloud optical depths in GEOS-3 generally agree with the satellite retrieval products from the Moderate Resolution Imaging Spectroradiometer (MODIS) and the International Satellite Cloud Climatology Project (ISCCP) within ±10%, while those in GEOS1-STRAT and GEOS-4 are too low by factors of about 5 and 2, respectively. With respect to vertical distribution, clouds in GEOS-4 are optically much thinner in the tropical upper troposphere compared to those in GEOS1-STRAT and GEOS-3. Assuming linear scaling of cloud optical depth with cloud fraction in a grid-box, our model calculations indicate that the changes in global mean hydroxyl radical (OH) due to the radiative effect of clouds in June are about -1% (GEOS1-STRAT), 1% (GEOS-3), and 14% (GEOS-4), respectively. The effects on global mean OH are similar for GEOS1-STRAT and GEOS-3 due to similar vertical distributions of clouds, even though the column cloud optical depths in the two archives differ by a factor of about 5. Clouds in GEOS-4 have a much larger impact on global mean OH because more solar radiation is

  18. Assessing MODIS Macrophysical Cloud Property Uncertainties

    NASA Astrophysics Data System (ADS)

    Maddux, B. C.; Ackerman, S. A.; Frey, R.; Holz, R.

    2013-12-01

    Cloud, being multifarious and ephemeral, is difficult to observe and quantify in a systematic way. Even basic terminology used to describe cloud observations is fraught with ambiguity in the scientific literature. Any observational technique, method, or platform will contain inherent and unavoidable measurement uncertainties. Quantifying these uncertainties in cloud observations is a complex task that requires an understanding of all aspects of the measurement. We will use cloud observations obtained from the Moderate Resolution Imaging Spectroradiameter(MODIS) to obtain metrics of the uncertainty of its cloud observations. Our uncertainty analyses will contain two main components, 1) an attempt to create a bias or uncertainty with respect to active measurements from CALIPSO and 2) a relative uncertainty within the MODIS cloud climatologies themselves. Our method will link uncertainty to the physical observation and its environmental/scene characteristics. Our aim is to create statistical uncertainties that are based on the cloud observational values, satellite view geometry, surface type, etc, for cloud amount and cloud top pressure. The MODIS instruments on the NASA Terra and Aqua satellites provide observations over a broad spectral range (36 bands between 0.415 and 14.235 micron) and high spatial resolution (250 m for two bands, 500 m for five bands, 1000 m for 29 bands), which the MODIS cloud mask algorithm (MOD35) utilizes to provide clear/cloud determinations over a wide array of surface types, solar illuminations and view geometries. For this study we use the standard MODIS products, MOD03, MOD06 and MOD35, all of which were obtained from the NASA Level 1 and Atmosphere Archive and Distribution System.

  19. The Role of Cloud-Scale Resolution on Radiative Properties of Oceanic Cumulus Clouds

    SciTech Connect

    Kassianov, Evgueni I.; Ackerman, Thomas P.; Kollias, Pavlos

    2005-03-01

    Both individual and combined effects of the horizontal and vertical variability of cumulus clouds on solar radiative transfer were investigated using a two-dimensional (x- and z-directions) cloud radar dataset. This high-resolution dataset of typical fair-weather marine cumulus was derived from ground-based 94-GHz cloud radar observations. The domain-averaged (along x-direction) radiative properties were computed by a Monte Carlo method. It is shown that (1) different cloud-scale resolutions can be used for accurate calculations of the mean absorption, upward and downward fluxes; (2) the resolution effects can depend strongly on the solar zenith angle; and (3) a few cloud statistics can be successfully applied for calculating the averaged radiative properties.

  20. Cloud microphysics and surface properties in climate

    SciTech Connect

    Stamnes, K.

    1995-09-01

    Cloud optical thickness is determined from ground-based measurements of broadband incoming solar irradiance using a radiation model in which the cloud optical depth is adjusted until computed irradiance agrees with the measured value. From spectral measurements it would be feasible to determine both optical thickness and mean drop size, which apart from cloud structure and morphology, are the most important climatic parameters of clouds. A radiative convective model is used to study the sensitivity of climate to cloud liquid water amount and cloud drop size. This is illustrated in Figure 21.1 which shows that for medium thick clouds a 10 % increase in drop size yields a surface warming of 1.5{degrees}C, which is the same as that due to a doubling of carbon dioxide. For thick clouds, a 5% decrease in drop size is sufficient to offset the warming due to doubling of carbon dioxide. A radiative transfer model for the coupled atmosphere/sea ice/ocean system is used to study the partitioning of radiative energy between the three strata, and the potential for testing such a model in terms of planned experiments in the Arctic is discussed.

  1. Global Ice Cloud Properties Based on CALIPSO and CloudSat Measurements and Their Radiative Effect

    NASA Astrophysics Data System (ADS)

    Hong, Y.; Liu, G.

    2013-12-01

    The radiative influence of atmospheric ice clouds varies widely from shortwave to longwave. This frequency-dependent response is convenient, and various techniques have been developed to better understand ice cloud properties. In recent years, the joint observations of the CloudSat Radar and Infrared Pathfinder Satellite Observations (CALIPSO) lidar have frequently been used to examine clouds of varying optical depth (OD). The former excels in probing thick clouds, usually associated with cooling, while the latter performs better with thin clouds, which are generally associated with localized warming. This study aims at investigating global ice cloud properties based on DarDar (raDar/liDar) data that combines both lidar and radar observations, while at the same modeling ice cloud radiative effects. Using DarDar data, this study firstly examines global Ice Water Path (IWP), and shows a global mean IWP value of 113.55 g/m2 for all measurements and 196.34 g/m2 for cloudy situations. The global frequency of ice cloud occurrence reveals that ice clouds predominate in deep convectional regions and storm tracks. Conversely, the subtropics contain fewer ice clouds. Due to Intertropical Convergence Zone (ITCZ) seasonal shifting and storm seasonal changes, a global map of ice cloud occurrence likewise varies seasonally. Global ice cloud occurrence also depends on the day-night cycle. Occurrence at night is 4.8% higher than during the day. IWP, on the contrary, is 1.75 g/m2 lower at night. There is considerable variation among sampled clouds, in which the visible OD ranges from near zero to over 100. Within this range, thin cirrus with OD < 3.0 are most common (75.87%). To better ascertain ice cloud properties, we group ice clouds into five bins according to visible OD: 0 < OD < 0.03, 0.03 < OD < 0.3, 0.3 < OD < 3.0, 3.0 < OD < 20 and OD > 20. The ice clouds with lowest OD are common at midlatitudes, while those with largest OD occur mostly in tropical convective zones and

  2. Radiation properties and emissivity parameterization of high level thin clouds

    NASA Technical Reports Server (NTRS)

    Wu, M.-L. C.

    1984-01-01

    To parameterize emissivity of clouds at 11 microns, a study has been made in an effort to understand the radiation field of thin clouds. The contributions to the intensity and flux from different sources and through different physical processes are calculated by using the method of successive orders of scattering. The effective emissivity of thin clouds is decomposed into the effective absorption emissivity, effective scattering emissivity, and effective reflection emissivity. The effective absorption emissivity depends on the absorption and emission of the cloud; it is parameterized in terms of optical thickness. The effective scattering emissivity depends on the scattering properties of the cloud; it is parameterized in terms of optical thickness and single scattering albedo. The effective reflection emissivity follows the similarity relation as in the near infrared cases. This is parameterized in terms of the similarity parameter and optical thickness, as well as the temperature difference between the cloud and ground.

  3. Evidence for Natural Variability in Marine Stratocumulus Cloud Properties Due to Cloud-Aerosol

    NASA Technical Reports Server (NTRS)

    Albrecht, Bruce; Sharon, Tarah; Jonsson, Haf; Minnis, Patrick; Minnis, Patrick; Ayers, J. Kirk; Khaiyer, Mandana M.

    2004-01-01

    In this study, aircraft observations from the Interdisciplinary Remotely-Piloted Aircraft Studies (CIRPAS) Twin Otter are used to characterize the variability in drizzle, cloud, and aerosol properties associated with cloud rifts and the surrounding solid clouds observed off the coast of California. A flight made on 16 July 1999 provided measurements directly across an interface between solid and rift cloud conditions. Aircraft instrumentation allowed for measurements of aerosol, cloud droplet, and drizzle spectra. CCN concentrations were measured in addition to standard thermodynamic variables and the winds. A Forward Scatter Spectrometer Probe (FSSP) measured size distribution of cloud-sized droplets. A Cloud Imaging Probe (CIP) was used to measure distributions of drizzle-sized droplets. Aerosol distributions were obtained from a Cloud Aerosol Scatterprobe (CAS). The CAS probe measured aerosols, cloud droplets and drizzle-sized drops; for this study. The CAS probe was used to measure aerosols in the size range of 0.5 micron - 1 micron. Smaller aerosols were characterized using an Ultrafine Condensation Particle Counter (CPC) sensor. The CPC was used to measure particles with diameters greater than 0.003 micron. By subtracting different count concentrations measured with the CPC, this probe was capable of identifying ultrafine particles those falling in the size range of 3 nanometers - 7 nanometers that are believed to be associated with new particle production.

  4. Role of Gravity Waves in Determining Cirrus Cloud Properties

    NASA Technical Reports Server (NTRS)

    OCStarr, David; Singleton, Tamara; Lin, Ruei-Fong

    2008-01-01

    Cirrus clouds are important in the Earth's radiation budget. They typically exhibit variable physical properties within a given cloud system and from system to system. Ambient vertical motion is a key factor in determining the cloud properties in most cases. The obvious exception is convectively generated cirrus (anvils), but even in this case, the subsequent cloud evolution is strongly influenced by the ambient vertical motion field. It is well know that gravity waves are ubiquitous in the atmosphere and occur over a wide range of scales and amplitudes. Moreover, researchers have found that inclusion of statistical account of gravity wave effects can markedly improve the realism of simulations of persisting large-scale cirrus cloud features. Here, we use a 1 -dimensional (z) cirrus cloud model, to systematically examine the effects of gravity waves on cirrus cloud properties. The model includes a detailed representation of cloud microphysical processes (bin microphysics and aerosols) and is run at relatively fine vertical resolution so as to adequately resolve nucleation events, and over an extended time span so as to incorporate the passage of multiple gravity waves. The prescribed gravity waves "propagate" at 15 m s (sup -1), with wavelengths from 5 to 100 km, amplitudes range up to 1 m s (sup -1)'. Despite the fact that the net gravity wave vertical motion forcing is zero, it will be shown that the bulk cloud properties, e.g., vertically-integrated ice water path, can differ quite significantly from simulations without gravity waves and that the effects do depend on the wave characteristics. We conclude that account of gravity wave effects is important if large-scale models are to generate realistic cirrus cloud property climatology (statistics).

  5. Satellite remote sensing of aerosol and cloud properties over Eurasia

    NASA Astrophysics Data System (ADS)

    Sogacheva, Larisa; Kolmonen, Pekka; Saponaro, Giulia; Virtanen, Timo; Rodriguez, Edith; Sundström, Anu-Maija; Atlaskina, Ksenia; de Leeuw, Gerrit

    2015-04-01

    Satellite remote sensing provides the spatial distribution of aerosol and cloud properties over a wide area. In our studies large data sets are used for statistical studies on aerosol and cloud interaction in an area over Fennoscandia, the Baltic Sea and adjacent regions over the European mainland. This area spans several regimes with different influences on aerosol cloud interaction such as a the transition from relative clean air over Fennoscandia to more anthropogenically polluted air further south, and the influence maritime air over the Baltic and oceanic air advected from the North Atlantic. Anthropogenic pollution occurs in several parts of the study area, and in particular near densely populated areas and megacities, but also in industrialized areas and areas with dense traffic. The aerosol in such areas is quite different from that produced over the boreal forest and has different effects on air quality and climate. Studies have been made on the effects of aerosols on air quality and on the radiation balance in China. The aim of the study is to study the effect of these different regimes on aerosol-cloud interaction using a large aerosol and cloud data set retrieved with the (Advanced) Along Track Scanning Radiometer (A)ATSR Dual View algorithm (ADV) further developed at Finnish Meteorological Institute and aerosol and cloud data provided by MODIS. Retrieval algorithms for aerosol and clouds have been developed for the (A)ATSR, consisting of a series of instruments of which we use the second and third one: ATSR-2 which flew on the ERS-2 satellite (1995-2003) and AATSR which flew on the ENVISAT satellite (2002-2012) (both from the European Space Agency, ESA). The ADV algorithm provides aerosol data on a global scale with a default resolution of 10x10km2 (L2) and an aggregate product on 1x1 degree (L3). Optional, a 1x1 km2 retrieval products is available over smaller areas for specific studies. Since for the retrieval of AOD no prior knowledge is needed on

  6. Low cloud investigations for project FIRE: Island studies of cloud properties, surface radiation, and boundary layer dynamics. A simulation of the reflectivity over a stratocumulus cloud deck by the Monte Carlo method. M.S. Thesis Final Report

    NASA Technical Reports Server (NTRS)

    Ackerman, Thomas P.; Lin, Ruei-Fong

    1993-01-01

    The radiation field over a broken stratocumulus cloud deck is simulated by the Monte Carlo method. We conducted four experiments to investigate the main factor for the observed shortwave reflectively over the FIRE flight 2 leg 5, in which reflectivity decreases almost linearly from the cloud center to cloud edge while the cloud top height and the brightness temperature remain almost constant through out the clouds. From our results, the geometry effect, however, did not contribute significantly to what has been observed. We found that the variation of the volume extinction coefficient as a function of its relative position in the cloud affects the reflectivity efficiently. Additional check of the brightness temperature of each experiment also confirms this conclusion. The cloud microphysical data showed some interesting features. We found that the cloud droplet spectrum is nearly log-normal distributed when the clouds were solid. However, whether the shift of cloud droplet spectrum toward the larger end is not certain. The decrease of number density from cloud center to cloud edges seems to have more significant effects on the optical properties.

  7. Impact of cloud processes on aerosol particle properties: results from two ATR-42 flights in an extended stratocumulus cloud layer during the EUCAARI campaign (2008)

    NASA Astrophysics Data System (ADS)

    Crumeyrolle, S.; Weigel, R.; Sellegri, K.; Roberts, G.; Gomes, L.; Stohl, A.; Laj, P.; Bourianne, T.; Etcheberry, J. M.; Villani, P.; Pichon, J. M.; Schwarzenboeck, A.

    2011-12-01

    Within the European Aerosol Cloud Climate and Air Quality Interactions (EUCAARI) project, the Meteo France research aircraft ATR-42 was operated from Rotterdam airport during May 2008, to perform scientific flights dedicated to the investigation of aerosol-cloud interactions. Therein, the objective of this study is to illustrate the impact of cloud processing on the aerosol particles physical and chemical properties. The presented results are retrieved from measurements during a double-flight mission from Rotterdam (Netherlands) to Newcastle (UK) and back using data measured with compact Time of Flight Aerosol Mass Spectrometer (cToF-AMS) and Scanning Mobility Particle Sizer (SMPS). Cloud-related measurements during these flights were performed over the North Sea within as well as in close vicinity of a marine stratocumulus cloud layer. Particle physical and chemical properties observed in the close vicinity (V), below and above the stratocumulus cloud show strong differences. Firstly, measurements at constant altitude above the cloud layer show decreasing mass concentrations with decreasing horizontal distance (210-0 km) to the cloud layer by a factor up to 7, whereas below the cloud and by same means of distance, the mass concentrations merely decrease by a factor of 2 on average. Secondly, the averaged aerosol size distributions, observed above and below the cloud layer, are of bimodal character with pronounced minima between Aitken and accumulation mode which is potentially the consequence of cloud processing. Finally, the chemical composition of aerosol particles is strongly dependent on the location relative to the cloud layer (vicinity or below/above cloud). In general, the nitrate and organic fractions decrease with decreasing distance to the cloud, in the transit from cloud-free conditions towards the cloud boundaries. The decrease of nitrate and organic compounds ranges at a factor of three to ten, affecting sulfate and ammonium compounds to be

  8. Cloud Scavenging Effects on Aerosol Radiative and Cloud-nucleating Properties - Final Technical Report

    SciTech Connect

    Ogren, John A.; Sheridan, Patrick S.; Andrews, Elisabeth

    2009-03-05

    The optical properties of aerosol particles are the controlling factors in determining direct aerosol radiative forcing. These optical properties depend on the chemical composition and size distribution of the aerosol particles, which can change due to various processes during the particles’ lifetime in the atmosphere. Over the course of this project we have studied how cloud processing of atmospheric aerosol changes the aerosol optical properties. A counterflow virtual impactor was used to separate cloud drops from interstitial aerosol and parallel aerosol systems were used to measure the optical properties of the interstitial and cloud-scavenged aerosol. Specifically, aerosol light scattering, back-scattering and absorption were measured and used to derive radiatively significant parameters such as aerosol single scattering albedo and backscatter fraction for cloud-scavenged and interstitial aerosol. This data allows us to demonstrate that the radiative properties of cloud-processed aerosol can be quite different than pre-cloud aerosol. These differences can be used to improve the parameterization of aerosol forcing in climate models.

  9. Global, seasonal cloud variations from satellite radiance measurements. II - Cloud properties and radiative effects

    NASA Technical Reports Server (NTRS)

    Rossow, William B.; Lacis, Andrew A.

    1990-01-01

    Cloud and surface radiative properties and their effects on the earth and surface radiation budgets are obtained based on global daily visible and IR radiance measurements. The magnitude of cloud property variations and their effects on radiation increase strongly with decreasing space/time scales. Cloud properties are systematically different between land and ocean, with ocean having larger cloud cover with somewhat larger optical thicknesses and lower cloud top altitudes. Although cloud variations appear to be the primary cause of regional radiation budget variability at 5-30 daytime scales, the effects of their seasonal variations at larger spatial scales are less important than the changes associated with changes in solar declination and atmospheric/surface temperatures. The largest seasonal variations in radiation occur in the 30-60 deg latitude band in each hemisphere. Although clouds have a net cooling effect on the global, annual mean radiation balance at both the top of the atmosphere and the surface, their net effect on regional, seasonal balances is much more varied.

  10. Physical properties of giant molecular clouds in the Large Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Hughes, A.; Wong, T.; Ott, J.; Muller, E.; Pineda, J. L.; Mizuno, Y.; Bernard, J.-P.; Paradis, D.; Maddison, S.; Reach, W. T.; Staveley-Smith, L.; Kawamura, A.; Meixner, M.; Kim, S.; Onishi, T.; Mizuno, N.; Fukui, Y.

    2010-08-01

    The Magellanic Mopra Assessment (MAGMA) is a high angular resolution 12CO (J = 1 -> 0) mapping survey of giant molecular clouds (GMCs) in the Large Magellanic Cloud (LMC) and Small Magellanic Cloud using the Mopra Telescope. Here we report on the basic physical properties of 125 GMCs in the LMC that have been surveyed to date. The observed clouds exhibit scaling relations that are similar to those determined for Galactic GMCs, although LMC clouds have narrower linewidths and lower CO luminosities than Galactic clouds of a similar size. The average mass surface density of the LMC clouds is 50 Msolarpc-2, approximately half that of GMCs in the inner Milky Way. We compare the properties of GMCs with and without signs of massive star formation, finding that non-star-forming GMCs have lower peak CO brightness than star-forming GMCs. We compare the properties of GMCs with estimates for local interstellar conditions: specifically, we investigate the HI column density, radiation field, stellar mass surface density and the external pressure. Very few cloud properties demonstrate a clear dependence on the environment; the exceptions are significant positive correlations between (i) the HI column density and the GMC velocity dispersion, (ii) the stellar mass surface density and the average peak CO brightness and (iii) the stellar mass surface density and the CO surface brightness. The molecular mass surface density of GMCs without signs of massive star formation shows no dependence on the local radiation field, which is inconsistent with the photoionization-regulated star formation theory proposed by McKee. We find some evidence that the mass surface density of the MAGMA clouds increases with the interstellar pressure, as proposed by Elmegreen, but the detailed predictions of this model are not fulfilled once estimates for the local radiation field, metallicity and GMC envelope mass are taken into account.

  11. Comparison of retrieved noctilucent cloud particle properties from Odin tomography scans and model simulations

    NASA Astrophysics Data System (ADS)

    Megner, Linda; Christensen, Ole M.; Karlsson, Bodil; Benze, Susanne; Fomichev, Victor I.

    2016-12-01

    Mesospheric ice particles, known as noctilucent clouds or polar mesospheric clouds, have long been observed by rocket instruments, satellites and ground-based remote sensing, while models have been used to simulate ice particle growth and cloud properties. However, the fact that different measurement techniques are sensitive to different parts of the ice particle distribution makes it difficult to compare retrieved parameters such as ice particle radius or ice concentration from different experiments. In this work we investigate the accuracy of satellite retrieval based on scattered light and how this affects derived cloud properties. We apply the retrieval algorithm on spectral signals calculated from modelled cloud distributions and compare the results to the properties of the original distributions. We find that ice mass density is accurately retrieved whereas mean radius is often overestimated and high ice concentrations are generally underestimated. The reason is partly that measurements based on scattered light are insensitive to the smaller particles and partly that the retrieval algorithm assumes a Gaussian size distribution. Once we know the limits of the satellite retrieval we proceed to compare the properties retrieved from the modelled cloud distributions to those observed by the Optical, Spectroscopic, and Infrared Remote Imaging System (OSIRIS) instrument on the Odin satellite. We find that a model with a stationary atmosphere, as given by average atmospheric conditions, does not yield cloud properties that are in agreement with the observations, whereas a model with realistic temperature and vertical wind variations does. This indicates that average atmospheric conditions are insufficient to understand the process of noctilucent cloud growth and that a realistic atmospheric variability is crucial for cloud formation and growth. Further, the agreement between results from the model, when set up with a realistically variable atmosphere, and the

  12. The physical properties of the interstellar cloud around the heliosphere

    NASA Astrophysics Data System (ADS)

    Gry, C.

    2015-12-01

    A new interpretation of interstellar absorption lines in the spectra of nearby stars indicates that the medium surrounding the Sun can be regarded as a single, coherent cloud if we relax the assumption that a cloud behaves like a rigid body. This outlook permits us to construct a comprehensive picture of the local interstellar cloud and reveals that it departs from homogeneity in a number of aspects and physical properties: - This local cloud undergoes a deformation related to a compression in the direction of motion and an expansion in perpendicular directions, much like a squashed balloon. - The metal abundances decrease steadily from the rear to the head of the cloud, and this phenomenon does not appear to be related to ionization effects. - The cloud average HI density, estimated toward a number of nearby stars around which an astrophere is detected in Lyman alpha, varies from 0.03 to 0.1 cm-3. The cloud outer boundary inferred from the average density and column densities is very irregular with an average distance to the Sun of 9 +/- 7 pc. - The electron density and the cloud temperature can be derived from the combination of the ionization equilibrium of MgI and the excitation of CII in a restricted number of sightlines where column density is such that MgI and CII* features are strong enough to be detectable without saturating MgII. We present a few additional targets from which we examine the physical conditions inside the cloud.

  13. Depolarization Lidar Determination Of Cloud-Base Microphysical Properties

    NASA Astrophysics Data System (ADS)

    Donovan, D. P.; Klein Baltink, H.; Henzing, J. S.; de Roode, S.; Siebesma, A. P.

    2016-06-01

    The links between multiple-scattering induced depolarization and cloud microphysical properties (e.g. cloud particle number density, effective radius, water content) have long been recognised. Previous efforts to use depolarization information in a quantitative manner to retrieve cloud microphysical cloud properties have also been undertaken but with limited scope and, arguably, success. In this work we present a retrieval procedure applicable to liquid stratus clouds with (quasi-)linear LWC profiles and (quasi-)constant number density profiles in the cloud-base region. This set of assumptions allows us to employ a fast and robust inversion procedure based on a lookup-table approach applied to extensive lidar Monte-Carlo multiple-scattering calculations. An example validation case is presented where the results of the inversion procedure are compared with simultaneous cloud radar observations. In non-drizzling conditions it was found, in general, that the lidar- only inversion results can be used to predict the radar reflectivity within the radar calibration uncertainty (2-3 dBZ). Results of a comparison between ground-based aerosol number concentration and lidar-derived cloud base number considerations are also presented. The observed relationship between the two quantities is seen to be consistent with the results of previous studies based on aircraft-based in situ measurements.

  14. Ice Cloud Properties in Ice-Over-Water Cloud Systems Using TRMM VIRS and TMI Data

    NASA Technical Reports Server (NTRS)

    Minnis, Patrick; Huang, Jianping; Lin, Bing; Yi, Yuhong; Arduini, Robert F.; Fan, Tai-Fang; Ayers, J. Kirk; Mace, Gerald G.

    2007-01-01

    A multi-layered cloud retrieval system (MCRS) is updated and used to estimate ice water path in maritime ice-over-water clouds using Visible and Infrared Scanner (VIRS) and TRMM Microwave Imager (TMI) measurements from the Tropical Rainfall Measuring Mission spacecraft between January and August 1998. Lookup tables of top-of-atmosphere 0.65- m reflectance are developed for ice-over-water cloud systems using radiative transfer calculations with various combinations of ice-over-water cloud layers. The liquid and ice water paths, LWP and IWP, respectively, are determined with the MCRS using these lookup tables with a combination of microwave (MW), visible (VIS), and infrared (IR) data. LWP, determined directly from the TMI MW data, is used to define the lower-level cloud properties to select the proper lookup table. The properties of the upper-level ice clouds, such as optical depth and effective size, are then derived using the Visible Infrared Solar-infrared Split-window Technique (VISST), which matches the VIRS IR, 3.9- m, and VIS data to the multilayer-cloud lookup table reflectances and a set of emittance parameterizations. Initial comparisons with surface-based radar retrievals suggest that this enhanced MCRS can significantly improve the accuracy and decrease the IWP in overlapped clouds by 42% and 13% compared to using the single-layer VISST and an earlier simplified MW-VIS-IR (MVI) differencing method, respectively, for ice-over-water cloud systems. The tropical distribution of ice-over-water clouds is the same as derived earlier from combined TMI and VIRS data, but the new values of IWP and optical depth are slightly larger than the older MVI values, and exceed those of single-layered layered clouds by 7% and 11%, respectively. The mean IWP from the MCRS is 8-14% greater than that retrieved from radar retrievals of overlapped clouds over two surface sites and the standard deviations of the differences are similar to those for single-layered clouds. Examples

  15. Development of advanced cloud parameterizations to examine air quality, cloud properties, and cloud-radiation feedback in mesoscale models

    SciTech Connect

    Lee, In Young

    1993-09-01

    The distribution of atmospheric pollutants is governed by dynamic processes that create the general conditions for transport and mixing, by microphysical processes that control the evolution of aerosol and cloud particles, and by chemical processes that transform chemical species and form aerosols. Pollutants emitted into the air can undergo homogeneous gas reactions to create a suitable environment for the production by heterogeneous nucleation of embryos composed of a few molecules. The physicochemical properties of preexisting aerosols interact with newly produced embryos to evolve by heteromolecular diffusion and coagulation. Hygroscopic particles wig serve as effective cloud condensation nuclei (CCN), while hydrophobic particles will serve as effective ice-forming nuclei. Clouds form initially by condensation of water vapor on CCN and evolve in a vapor-liquid-solid system by deposition, sublimation, freezing, melting, coagulation, and breakup. Gases and aerosols that enter the clouds undergo aqueous chemical processes and may acidity hydrometer particles. Calculations for solar and longwave radiation fluxes depend on how the respective spectra are modified by absorbers such as H{sub 2}O, CO{sub 2}, O{sub 3}, CH{sub 4}, N{sub 2}O, chlorofruorocarbons, and aerosols. However, the flux calculations are more complicated for cloudy skies, because the cloud optical properties are not well defined. In this paper, key processes such as tropospheric chemistry, cloud microphysics parameterizations, and radiation schemes are reviewed in terms of physicochemical processes occurring, and recommendations are made for the development of advanced modules applicable to mesoscale models.

  16. Remote sensing cloud properties from high spectral resolution infrared observations

    NASA Technical Reports Server (NTRS)

    Smith, William L.; Ma, Xia L.; Ackerman, Steven A.; Revercomb, H. E.; Knuteson, R. O.

    1993-01-01

    A technique for estimating cloud radiative properties (spectral emissivity and reflectivity) in the IR is developed based on observations at a spectral resolution of approximately 0.5/cm. The algorithm uses spectral radiance observations and theoretical calculations of the IR spectra for clear and cloudy conditions along with lidar-determined cloud-base and cloud-top pressure. An advantage of the high spectral resolution observations is that the absorption effects of atmospheric gases are minimized by analyzing between gaseous absorption lines. The technique is applicable to both ground-based and aircraft-based platforms and derives the effective particle size and associated cloud water content required to satisfy, theoretically, the observed cloud IR spectra. The algorithm is tested using theoretical simulations and applied to observations made with the University of Wisconsin's ground-based and NASA ER-2 aircraft High-Resolution Infrared Spectrometer instruments.

  17. Cloud optical properties and phase discrimination using transmitted spectral radiance

    NASA Astrophysics Data System (ADS)

    LeBlanc, S. E.; Pilewskie, P.; Schmidt, S.; Coddington, O.

    2013-12-01

    Cloud optical thickness, effective radius, and thermodynamic phase are commonly retrieved from satellite measurements of reflected light. Reflected light is influenced most strongly by droplets and ice crystals near cloud top, whereas transmitted light has interacted with cloud particles throughout the entire layer. This transmitted spectral radiance is used in a new method to retrieve cloud thermodynamic phase, cloud optical thickness, and effective radius. The method uses 15 regions of the shortwave transmittance spectrum that are modulated by the spectral absorption and scattering by liquid water droplets and ice particles. Spectral features in these regions are characterized by their slope, normalized magnitude, spectral derivatives, spectral curvature, and second derivatives. We use an optimal estimation method to find the most likely set of cloud optical thickness, effective radius, and thermodynamic phase that produces the observed spectral features in transmitted radiance spectra. This retrieval's performance is evaluated using the GEneralized Nonlinear Retrieval Analysis (GENRA) with the Shannon information content. Results showed that the normalized Shannon information content for retrieved ice cloud properties was larger on average (84%) than for liquid water cloud properties (78%) in addition to having a smaller bias. The retrieval was applied to zenith spectral radiance measured with the ground-based Solar Spectral Flux Radiometer (SSFR) located at Boulder, Colorado for 10 cases that occurred between May 2012 and January 2013. Retrieved cloud optical thickness, effective radius, and their uncertainties are compared to those retrieved using two other methods. By using several spectral characterizations in a large number of spectral bands, the average uncertainty in retrieved optical thickness and effective radius is reduced below that of any other retrieval method based on cloud transmittance.

  18. Macrophysical and optical properties of midlatitude high-altitude clouds from 4 ground-based lidars and collocated CALIOP observations

    NASA Astrophysics Data System (ADS)

    Dupont, J. C.; Haeffelin, M.; Morille, Y.; Noel, V.; Keckhut, P.; Comstock, J.; Winker, D.; Chervet, P.; Roblin, A.

    2009-04-01

    Cirrus clouds not only play a major role in the energy budget of the Earth-Atmosphere system, but are also important in the hydrological cycle [Stephens et al., 1990; Webster, 1994]. According to satellite passive remote sensing, high-altitude clouds cover as much as 40% of the earth's surface on average (Liou 1986; Stubenrauch et al., 2006) and can reach 70% of cloud cover over the Tropics (Wang et al., 1996; Nazaryan et al., 2008). Hence, given their very large cloud cover, they have a major role in the climate system (Lynch et al. 2001). Cirrus clouds can be classified into three distinct families according to their optical thickness, namely subvisible clouds (OD<0.03), semi-transparent clouds (0.03clouds (0.3clouds represent 50% or more of cirrus cloud population. The radiative effects of cirrus clouds are found to be significant by many studies both at the top of the atmosphere and surface. The contribution of the subvisible and semi-transparent classes is strongly affected by levels of other scatterers in the atmosphere (gases, aerosols). This makes them quite an important topic of study at the global scale. In the present work, we applied the cloud structure analysis algorithm STRAT to long time series of lidar backscatter profiles from multiple locations around the world. Our goal was to establish a Mid-Latitude climatology of cirrus clouds macrophysical properties based on active remote sensing: ground-based lidars at four mid-latitude observatories and the spaceborne instrument CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization). Lidar sampling, macrophysical (cloud base height, cloud top height, cloud thickness) and optical (cloud optical thickness) properties statistics are then evaluated and compared between the four observatories ground-based lidar measurements and quasi-simultaneously CALIOP overpasses. We note an overall good

  19. Cloud Properties Derived from Visible and Near-infrared Reflectance in the Presence of Aerosols

    NASA Astrophysics Data System (ADS)

    Pilewskie, P.; Hofmann, O.; Kindel, B.; Gore, W.; Russell, P.; Livingston, J.; Redemann, J.; Bergstrom, R.; Platnick, S.; Daniel, J.; Garrett, T.

    2005-12-01

    The New England Air Quality Study - Intercontinental Transport and Chemical Transformation (NEAQS-ITCT) experiment conducted in July-August 2004 included objectives on the effects of urban-industrial pollution aerosols on cloud radiative properties, the so-called indirect effect. Measurements of spectral irradiance covering the near-ultraviolet to near-infrared were made from two airborne platforms, the NOAA WP-3D and the Sky Research J-31, using identical Solar Spectral Flux Radiometers (SSFR). The SSFR measured the upwelling and downwelling spectral irradiance between 380-1670 nm from which the spectral albedo (ratio of upwelling to downwelling) and net (difference between downwelling and upwelling) irradiance were derived. Cloud spectral albedo was used to retrieve cloud particle effective radius, optical depth, and liquid water path. The robustness of the optical retrieval method will be examined by comparing the WP-3D SSFR retrievals to in situ measurements made with an FSSP-100 and an OAP 2D-C and to an independent retrieval using Miniaturized Differential Absorption Spectroscopy (MIDAS), also on board the WP-3D. A sunphotometer was also deployed on the J-31, the14-channel NASA Ames Airborne Tracking Sunphotometer (AATS-14), providing aerosol optical depths at thirteen discrete wavelengths between 354-2138 nm. J-31 flights on 15, 20, and 31 July were of particular interest because AATS-14 data revealed the presence aerosol layers above clouds. Comparisons between SSFR-derived cloud properties and MODIS cloud retrievals were in close agreement when aerosol optical depth was less than 0.1. Over moderately thick clouds there is evidence that an enhanced aerosol layer, such as that encountered during the 20 July case, may affect the retrieved cloud properties. Such an influence must be distinguished from a true "aerosol indirect effect" in order to accurately quantify the amount by which aerosols modify cloud albedo.

  20. Methods of editing cloud and atmospheric layer affected pixels from satellite data

    NASA Technical Reports Server (NTRS)

    Nixon, P. R. (Principal Investigator); Wiegand, C. L.; Richardson, A. J.; Johnson, M. P.; Goodier, B. G.

    1981-01-01

    The location and migration of cloud, land and water features were examined in spectral space (reflective VIS vs. emissive IR). Daytime HCMM data showed two distinct types of cloud affected pixels in the south Texas test area. High altitude cirrus and/or cirrostratus and "subvisible cirrus" (SCi) reflected the same or only slightly more than land features. In the emissive band, the digital counts ranged from 1 to over 75 and overlapped land features. Pixels consisting of cumulus clouds, or of mixed cumulus and landscape, clustered in a different area of spectral space than the high altitude cloud pixels. Cumulus affected pixels were more reflective than land and water pixels. In August the high altitude clouds and SCi were more emissive than similar clouds were in July. Four-channel TIROS-N data were examined with the objective of developing a multispectral screening technique for removing SCi contaminated data.

  1. Airborne In-Situ Measurements of Aerosol and Cloud Microphysical Properties in Mixed-Phase Clouds Under Varying Conditions

    NASA Astrophysics Data System (ADS)

    Comstock, J. M.; Fan, J.; Tomlinson, J. M.; Mei, F.; Hubbe, J. M.; Schmid, B.

    2014-12-01

    Cloud microphysical properties impact the interaction of clouds and radiation in the atmosphere, and can influence atmospheric circulations through changes in cloud phase. Characterizing the conditions that control phase changes and the microphysical properties of mixed-phase clouds is important for improving understanding of physical processes that influence cloud phase. We characterize the aerosol and cloud microphysical properties in relation to the atmospheric dynamic and thermodynamic conditions observed in mixed-phase clouds during several aircraft-based field experiments. The Department of Energy Atmospheric Radiation Measurement program's Gulfstream-1 aircraft was used to sample aerosol and cloud properties in warm and cold clouds during several recent field experiments. We analyze in-situ observations from the CalWater and TCAP field campaigns to examine the variability of cloud properties (phase, hydrometeor size, ice and liquid water content, particle habit) with changes in aerosol, vertical velocity, and temperature. These measurements indicate that in addition to aerosol concentration, vertical velocity strength has important influence on cloud phase in mixed-phase cloud regimes.

  2. Tropical Cloud Properties and Radiative Heating Profiles

    DOE Data Explorer

    Mather, James

    2008-01-15

    We have generated a suite of products that includes merged soundings, cloud microphysics, and radiative fluxes and heating profiles. The cloud microphysics is strongly based on the ARM Microbase value added product (Miller et al., 2003). We have made a few changes to the microbase parameterizations to address issues we observed in our initial analysis of the tropical data. The merged sounding product is not directly related to the product developed by ARM but is similar in that it uses the microwave radiometer to scale the radiosonde column water vapor. The radiative fluxes also differ from the ARM BBHRP (Broadband Heating Rate Profile) product in terms of the radiative transfer model and the sampling interval.

  3. Methods of editing cloud and atmospheric layer affected pixels from satellite data

    NASA Technical Reports Server (NTRS)

    Nixon, P. R.; Wiegand, C. L.; Richardson, A. J.; Johnson, M. P. (Principal Investigator)

    1982-01-01

    Subvisible cirrus clouds (SCi) were easily distinguished in mid-infrared (MIR) TIROS-N daytime data from south Texas and northeast Mexico. The MIR (3.55-3.93 micrometer) pixel digital count means of the SCi affected areas were more than 3.5 standard deviations on the cold side of the scene means. (These standard deviations were made free of the effects of unusual instrument error by factoring out the Ch 3 MIR noise on the basis of detailed examination of noisy and noise-free pixels). SCi affected areas in the IR Ch 4 (10.5-11.5 micrometer) appeared cooler than the general scene, but were not as prominent as in Ch 3, being less than 2 standard deviations from the scene mean. Ch 3 and 4 standard deviations and coefficients of variation are not reliable indicators, by themselves, of the presence of SCi because land features can have similar statistical properties.

  4. Comparison between observed and modelled radiative properties of stratocumulus clouds

    NASA Astrophysics Data System (ADS)

    Sun, Zhian; Pethick, David

    2002-10-01

    Measurements of radiative and microphysical characteristics of stratocumulus clouds in a coastal region of South Australia are reported. The measurements were taken on 14 April 1999 using two aircraft from Airborne Research Australia based at the Flinders University of South Australia during the Kangaroo Island Radiation and Cloud Experiments (KIRCE). The measurements include radiation, cloud liquid-water content, ambient temperature and humidity. A new method to process the measurements is described. Cloud albedo and absorption were determined using the observed solar irradiances at the cloud top and base and the results were compared with theoretical calculations. Five water-cloud optical parametrization schemes were tested against the observations. In addition, some observational data from the Joint Air-Sea Interaction (JASIN) experiment were used in the comparisons. It has been found that measured cloud properties from the KIRCE experiment are very similar to those of the JASIN experiment. The modelled results from most schemes are compatible and generally in good agreement with the measurements.

  5. Airborne observations of cloud properties on HALO during NARVAL

    NASA Astrophysics Data System (ADS)

    Konow, Heike; Hansen, Akio; Ament, Felix

    2016-04-01

    The representation of cloud and precipitation processes is one of the largest sources of uncertainty in climate and weather predictions. To validate model predictions of convective processes over the Atlantic ocean, usually satellite data are used. However, satellite products provide just a coarse view with poor temporal resolution of convective maritime clouds. Aircraft-based observations offer a more detailed insight due to lower altitude and high sampling rates. The research aircraft HALO (High Altitude Long Range Research Aircraft) is operated by the German Aerospace Center (DLR). With a ceiling of 15 km, and a range of 10,000 km and more than 10 hours it is able to reach remote regions and operate from higher altitudes than most other research aircraft. Thus, it provides the unique opportunity to exploit regions of the atmosphere that cannot be easily accessed otherwise. Measurements conducted on HALO provide more detailed insights than achievable from satellite data. Therefore, this measurement platform bridges the gap between previous airborne measurements and satellites. The payload used for this study consists of, amongst others, a suite of passive microwave radiometers, a cloud radar, and a water vapor DIAL. To investigate cloud and precipitation properties of convective maritime clouds, the NARVAL (Next-generation Aircraft Remote-Sensing for Validation Studies) campaign was conducted in winter 2013/2014 out of Barbados and Keflavik (Iceland). This campaign was one of the first that took place on the HALO aircraft. During the experiment's two parts 15 research flights were conducted (8 flights during NARVAL-South out of Barbados to investigate trade-wind cumuli and 7 flights out of Keflavik with focus on mid-latitude cyclonic systems). Flight durations were between five and nine hours, amounting to roughly 118 flight hours overall. 121 dropsondes were deployed. In fall 2016 two additional aircraft campaigns with the same payload will take place: The

  6. Airborne validation of cirrus cloud properties derived from CALIPSO lidar measurements: Spatial properties

    NASA Astrophysics Data System (ADS)

    Yorks, John E.; Hlavka, Dennis L.; Vaughan, Mark A.; McGill, Matthew J.; Hart, William D.; Rodier, Sharon; Kuehn, Ralph

    2011-10-01

    The Cloud-Aerosol Lidar Infrared Pathfinder Satellite Observations (CALIPSO) satellite was successfully launched in 2006 and has provided an unprecedented opportunity to study cloud and aerosol layers using range-resolved laser remote sensing. Dedicated validation flights were conducted using the airborne Cloud Physics Lidar (CPL) to validate the CALIPSO Level 1 and 2 data products. This paper presents results from coincident CALIPSO and CPL measurements of ice cloud spatial properties. Flight segment case studies are shown as well as statistics for all coincident measurements during the CALIPSO-CloudSat Validation Experiment (CC-VEX). CALIPSO layer detection algorithms for cirrus clouds are reliable in comparison with CPL, with best agreement occurring during nighttime coincident segments when the signal-to-noise ratio (SNR) of both instruments is greatest. However, the two instruments disagree on ice cloud spatial properties in two distinct cases. CALIPSO experiences less sensitivity to optically thin cirrus due to lower SNR when compared to CPL data at identical spatial scales. The incorporation of extended spatial averaging in the CALIPSO layer detection algorithm succeeds in detecting the optically thin cirrus, but the averaging process occasionally results in spatial smearing, both horizontally and vertically, of broken cirrus clouds. The second disparity occurs because, in contrast to CPL, multiple scattering contributes significantly to CALIPSO lidar measurements of cirrus clouds. As a result, the CALIPSO signal penetrates deeper into opaque cirrus clouds, and in these cases CALIPSO will report lower apparent cloud base altitudes than CPL.

  7. Influence of the Entrainment Interface Layer on Cloud Microphysical Properties near Stratocumulus Top

    NASA Astrophysics Data System (ADS)

    Chuang, P. Y.; Carman, J. K.; Rossiter, D. L.

    2010-12-01

    Entrainment across the stratocumulus-topped boundary layer is a key process governing the cloud properties and evolution. This process is not well-represented even in high-resolution large-eddy simulations, in part due to the sharp gradients in temperature, buoyancy and (usually) humidity that occur at the top of the boundary layer. In summer 2008, the Physics of Stratocumulus Top (POST) field campaign conduct extensive measurements in the vicinity of cloud top, including the so-called entrainment interface layer or EIL that separates boundary layer and free tropospheric air. Roughly half of the fifteen flights occurred during the day (near solar noon) while the remaining flights occurred during late evening-to-night when solar input was minimal. A wide diversity of EIL properties has been revealed over the course of the campaign. EIL vertical thickness diagnosed using total water varies from fairly thin (~20 m) to very thick (>100 m). The thickness and intensity of the turbulent layer in this interfacial region also varies substantially, with the top of the significantly turbulent region ranging from 10 m to 50 m above cloud top. Shear in the vicinity of cloud top also varied strongly from day-to-day. While almost all cases exhibited strong jumps in potential temperature, there are a number of cases where the jump in total water was very small-to-none, and one case where total water was higher in the free troposphere by 1.4 g/kg. POST thus demonstrates that the cloud-top interfacial region exhibits a rich and diverse range of properties. This study focuses on how this EIL diversity affects the stratocumulus cloud itself. We build on our study of the EIL dynamic and thermodynamic properties to investigate the influence of the EIL on the microphysical properties of the stratocumulus in the vicinity of cloud top. Entrainment of the overlying warmer and (usually) drier air can strongly impact the amount of liquid water as well as the size and concentration of cloud

  8. Improvements in Night-Time Low Cloud Detection and MODIS-Style Cloud Optical Properties from MSG SEVIRI

    NASA Technical Reports Server (NTRS)

    Wind, Galina (Gala); Platnick, Steven; Riedi, Jerome

    2011-01-01

    The MODIS cloud optical properties algorithm (MOD06IMYD06 for Terra and Aqua MODIS, respectively) slated for production in Data Collection 6 has been adapted to execute using available channels on MSG SEVIRI. Available MODIS-style retrievals include IR Window-derived cloud top properties, using the new Collection 6 cloud top properties algorithm, cloud optical thickness from VISINIR bands, cloud effective radius from 1.6 and 3.7Jlm and cloud ice/water path. We also provide pixel-level uncertainty estimate for successful retrievals. It was found that at nighttime the SEVIRI cloud mask tends to report unnaturally low cloud fraction for marine stratocumulus clouds. A correction algorithm that improves detection of such clouds has been developed. We will discuss the improvements to nighttime low cloud detection for SEVIRI and show examples and comparisons with MODIS and CALIPSO. We will also show examples of MODIS-style pixel-level (Level-2) cloud retrievals for SEVIRI with comparisons to MODIS.

  9. Preliminary study on direct assimilation of cloud-affected satellite microwave brightness temperatures

    NASA Astrophysics Data System (ADS)

    Zhang, Sibo; Guan, Li

    2017-02-01

    Direct assimilation of cloud-affected microwave brightness temperatures from AMSU-A into the GSI three-dimensional variational (3D-Var) assimilation system is preliminarily studied in this paper. A combination of cloud microphysics parameters retrieved by the 1D-Var algorithm (including vertical profiles of cloud liquid water content, ice water content, and rain water content) and atmospheric state parameters from objective analysis fields of an NWP model are used as background fields. Three cloud microphysics parameters (cloud liquid water content, ice water content, and rain water content) are applied to the control variable. Typhoon Halong (2014) is selected as an example. The results show that direct assimilation of cloud-affected AMSU-A observations can effectively adjust the structure of large-scale temperature, humidity and wind analysis fields due to the assimilation of more AMSU-A observations in typhoon cloudy areas, especially typhoon spiral cloud belts. These adjustments, with temperatures increasing and humidities decreasing in the movement direction of the typhoon, bring the forecasted typhoon moving direction closer to its real path. The assimilation of cloud-affected satellite microwave brightness temperatures can provide better analysis fields that are more similar to the actual situation. Furthermore, typhoon prediction accuracy is improved using these assimilation analysis fields as the initial forecast fields in NWP models.

  10. Using Radar, Lidar, and Radiometer measurements to Classify Cloud Type and Study Middle-Level Cloud Properties

    SciTech Connect

    Wang, Zhien

    2010-06-29

    The project is mainly focused on the characterization of cloud macrophysical and microphysical properties, especially for mixed-phased clouds and middle level ice clouds by combining radar, lidar, and radiometer measurements available from the ACRF sites. First, an advanced mixed-phase cloud retrieval algorithm will be developed to cover all mixed-phase clouds observed at the ACRF NSA site. The algorithm will be applied to the ACRF NSA observations to generate a long-term arctic mixed-phase cloud product for model validations and arctic mixed-phase cloud processes studies. To improve the representation of arctic mixed-phase clouds in GCMs, an advanced understanding of mixed-phase cloud processes is needed. By combining retrieved mixed-phase cloud microphysical properties with in situ data and large-scale meteorological data, the project aim to better understand the generations of ice crystals in supercooled water clouds, the maintenance mechanisms of the arctic mixed-phase clouds, and their connections with large-scale dynamics. The project will try to develop a new retrieval algorithm to study more complex mixed-phase clouds observed at the ACRF SGP site. Compared with optically thin ice clouds, optically thick middle level ice clouds are less studied because of limited available tools. The project will develop a new two wavelength radar technique for optically thick ice cloud study at SGP site by combining the MMCR with the W-band radar measurements. With this new algorithm, the SGP site will have a better capability to study all ice clouds. Another area of the proposal is to generate long-term cloud type classification product for the multiple ACRF sites. The cloud type classification product will not only facilitates the generation of the integrated cloud product by applying different retrieval algorithms to different types of clouds operationally, but will also support other research to better understand cloud properties and to validate model simulations. The

  11. Retrieving co-occurring cloud and precipitation properties of warm marine boundary layer clouds with A-Train data

    NASA Astrophysics Data System (ADS)

    Mace, Gerald G.; Avey, Stephanie; Cooper, Steven; Lebsock, Matthew; Tanelli, Simone; Dobrowalski, Greg

    2016-04-01

    In marine boundary layer (MBL) clouds the formation of precipitation from the cloud droplet distribution in the presence of variable aerosol plays a fundamental role in determining the coupling of these clouds to their environment and ultimately to the climate system. Here the degree to which A-Train satellite measurements can diagnose simultaneously occurring cloud and precipitation properties in MBL clouds is examined. Beginning with the measurements provided by CloudSat and Moderate Resolution Imaging Spectroradiometer (including a newly available microwave brightness temperature from CloudSat), and a climatology of MBL cloud properties from past field campaigns, an assumption is made that any hydrometeor volume could contain both cloud droplet and precipitation droplet modes. Bayesian optimal estimation is then used to derive atmospheric states by inverting a measurement vector carefully accounting for uncertainties due to instrument noise, forward model error, and assumptions. It is found that in many cases where significant precipitation coexists with cloud, due to forward model error driven by uncertainties in assumptions, the uncertainty in retrieved cloud properties is greater than the variance in the prior climatology. It is often necessary to average several thousand (hundred) precipitating (weakly precipitating) profiles to obtain meaningful information regarding the properties important to microphysical processes. Regardless, if such process level information is deemed necessary for better constraining predictive models of the climate system, measurement systems specifically designed to accomplish such retrievals must be considered for the future.

  12. Daytime Cloud Property Retrievals Over the Arctic from Multispectral MODIS Data

    NASA Technical Reports Server (NTRS)

    Spangenberg, Douglas A.; Trepte, Qing; Minnis, Patrick; Uttal, Taneil

    2004-01-01

    Improving climate model predictions over Earth's polar regions requires a complete understanding of polar clouds properties. Passive satellite remote sensing techniques can be used to retrieve macro and microphysical properties of polar cloud systems. However, over the Arctic, there is minimal contrast between clouds and the background snow surface observed in satellite data, especially for visible wavelengths. This makes it difficult to identify clouds and retrieve their properties from space. Variable snow and ice cover, temperature inversions, and the predominance of mixed-phase clouds further complicate cloud property identification. For this study, the operational Clouds and the Earth s Radiant Energy System (CERES) cloud mask is first used to discriminate clouds from the background surface in Terra Moderate Resolution Imaging Spectroradiometer (MODIS) data. A solar-infrared infrared nearinfrared technique (SINT) first used by Platnick et al. (2001) is used here to retrieve cloud properties over snow and ice covered regions.

  13. Cloud Macro- and Microphysical Properties Derived from GOES over the ARM SGP Domain

    NASA Technical Reports Server (NTRS)

    Minnis, P.; Smith, W. L., Jr.; Young, D. F.

    2001-01-01

    Cloud macrophysical properties like fractional coverage and height Z(sub c) and microphysical parameters such as cloud liquid water path (LWP), effective droplet radius r(sub e), and cloud phase, are key factors affecting both the radiation budget and the hydrological cycle. Satellite data have been used to complement surface observations from Atmospheric Radiation Measurements (ARM) by providing additional spatial coverage and top-of-atmosphere boundary conditions of these key parameters. Since 1994, the Geostationary Operational Environmental Satellite (GOES) has been used for deriving at each half-hour over the ARM Southern Great Plains (SGP) domain: cloud amounts, altitudes, temperatures, and optical depths as well as broadband shortwave (SW) albedo and outgoing longwave radiation at the top of the atmosphere. A new operational algorithm has been implemented to increase the number of value-added products to include cloud particle phase and effective size (r(sub e) or effective ice diameter D(sub e)) as well as LWP and ice water path. Similar analyses have been performed on the data from the Visible Infrared Scanner (VIRS) on the Tropical Rainfall Measuring Mission satellite as part of the Clouds and Earth's Radiant Energy System project. This larger suite of cloud properties will enhance our knowledge of cloud processes and further constrain the mesoscale and single column models using ARM data as a validation/initialization resource. This paper presents the results of applying this new algorithm to GOES-8 data taken during 1998 and 2000. The global VIRS results are compared to the GOES SGP results to provide appropriate context and to test consistency.

  14. Venus cloud properties inferred from limb darkening curves

    NASA Astrophysics Data System (ADS)

    Longobardo, A.; Palomba, E.; Piccioni, G.; Zinzi, A.; Tsang, C. C. C.; Drossart, P.

    2011-10-01

    The limb darkening (LD) curve is the plot of radiance I as function of cosine of the emission angle (i.e. angle between the line of sight and the normal to the target). Its shape is related to atmospheric and cloud properties, such as opacity and scale height. These can be deduced also considering the plot of brightness temperature T as function of cos at some wavelengths [1,2]. In this work, Venus clouds have been studied by means of a LD study on infrared images of the Venus nightside, provided by the VIRTIS-Venus Express instrument [3].

  15. Annual cycle of radiation fluxes over the Arctic ocean: Sensitivity to cloud optical properties

    SciTech Connect

    Curry, J.A. ); Ebert, E.E. )

    1992-11-01

    The relationship between cloud optical properties and the radiative fluxes over the Arctic Ocean is explored by conducting a series of modeling experiments. The annual cycle of arctic cloud optical properties that are required to reproduce both the outgoing radiative fluxes at the top of the atmosphere as determined from satellite observations and the available determinations of surface radiative fluxes are derived. Existing data on cloud fraction and cloud microphysical properties are utilized. Four types of cloud are considered: low stratus clouds, midlevel clouds, citrus clouds, and wintertime ice crystal precipitation. Internally consistent annual cycles of surface temperature, surface albedo, cloud fraction and cloud optical properties, components of surface and top of atmosphere radiative fluxes, and cloud radiative forcing are presented. The modeled total cloud optical depth (weighted by cloud fraction) ranges from a low value in winter of 2 to a high summertime value of 8. Infrared emmissivities for liquid water clouds are shown to be substantially less than unity during the cold half of the year. Values of modeled surface cloud radiative forcing are positive except for two weeks in midsummer; over the course of the year clouds have a net warming effect on the surface in the Arctic. Total cloud radiative forcing at the top of the atmosphere is determined to be positive only briefly in early autumn. Surface longwave fluxes are shown to be very sensitive to the presence of lower-tropospheric ice crystal precipitation during the cold half of the year.

  16. CCN and IN Effects on Cloud Properties and Precipitation - Case Studies from CalWater 2011

    NASA Astrophysics Data System (ADS)

    Fan, J.; Leung, L.; Comstock, J. M.; Tomlinson, J. M.

    2011-12-01

    Aerosols in the atmosphere can serve as cloud condensation nuclei (CCN) and ice nuclei (IN) to modify cloud microphysical processes, which could potentially change the location, intensity, and type of precipitation. Dust aerosols are often observed over California in the Sierra Nevada Mountains in winter/spring, associated with long-range transport from Asia. Although anthropogenic pollution has been postulated to contribute to reduction of precipitation in the Sierra Nevada Mountains, the effects of dust aerosols on the winter clouds and precipitation has not been examined in detail particularly with model simulations. We incorporate recent progress in ice nucleation parameterizations to link dust with ice crystal formation in a spectral-bin cloud microphysical model coupled with WRF, to exclusively look into how dust can possibly affect cloud properties and precipitation type and intensity. Simulations are carried out for two cases under different environmental conditions with atmospheric river (AR) and Sierra barrier jet (SBJ) from the CalWater 2011 field campaign. It is shown that increasing IN concentrations or adding a dust layer at 4-6 km as IN enhances surface rain and snow due to enhanced production of ice and snow in clouds. However, increasing CCN suppresses surface rain and snow, and significantly redistributes surface precipitation upwind and downwind of the mountains, with important implication to improving our understanding of the impacts of aerosols on orographic precipitation and water supply in the region.

  17. Characterization of Arctic ice cloud properties observed during ISDAC

    NASA Astrophysics Data System (ADS)

    Jouan, Caroline; Girard, Eric; Pelon, Jacques; Gultepe, Ismail; Delanoë, Julien; Blanchet, Jean-Pierre

    2012-12-01

    Extensive measurements from ground-based sites and satellite remote sensing (CloudSat and CALIPSO) reveal the existence of two types of ice clouds (TICs) in the Arctic during the polar night and early spring. The first type (TIC-2A), being topped by a cover of nonprecipitating very small (radar unseen) ice crystals (TIC-1), is found more frequently in pristine environment, whereas the second type (TIC-2B), detected by both sensors, is associated preferentially with a high concentration of aerosols. To further investigate the microphysical properties of TIC-1/2A and TIC-2B, airborne in situ and satellite measurements of specific cases observed during Indirect and Semi-Direct Aerosol Campaign (ISDAC) have been analyzed. For the first time, Arctic TIC-1/2A and TIC-2B microstructures are compared using in situ cloud observations. Results show that the differences between them are confined in the upper part of the clouds where ice nucleation occurs. TIC-2B clouds are characterized by fewer (by more than 1 order of magnitude) and larger (by a factor of 2 to 3) ice crystals and a larger ice supersaturation (of 15-20%) compared to TIC-1/2A. Ice crystal growth in TIC-2B clouds seems explosive, whereas it seems more gradual in TIC-1/2A. It is hypothesized that these differences are linked to the number concentration and the chemical composition of aerosols. The ice crystal growth rate in very cold conditions impinges on the precipitation efficiency, dehydration and radiation balance. These results represent an essential and important first step to relate previous modeling, remote sensing and laboratory studies with TICs cloud in situ observations.

  18. Investigation of Cloud Properties and Atmospheric Profiles with MODIS

    NASA Technical Reports Server (NTRS)

    Menzel, Paul; Ackerman, Steve; Moeller, Chris; Gumley, Liam; Strabala, Kathy; Frey, Richard; Prins, Elaine; LaPorte, Dan; Wolf, Walter

    1997-01-01

    The WINter Cloud Experiment (WINCE) was directed and supported by personnel from the University of Wisconsin in January and February. Data sets of good quality were collected by the MODIS Airborne Simulator (MAS) and other instruments on the NASA ER2; they will be used to develop and validate cloud detection and cloud property retrievals over winter scenes (especially over snow). Software development focused on utilities needed for all of the UW product executables; preparations for Version 2 software deliveries were almost completed. A significant effort was made, in cooperation with SBRS and MCST, in characterizing and understanding MODIS PFM thermal infrared performance; crosstalk in the longwave infrared channels continues to get considerable attention.

  19. Using Radar, Lidar, and Radiometer measurements to Classify Cloud Type and Study Middle-Level Cloud Properties

    SciTech Connect

    Wang, Zhien

    2006-01-04

    The project is concerned with the characterization of cloud macrophysical and microphysical properties by combining radar, lidar, and radiometer measurements available from the U.S. Department of Energy's ARM Climate Research Facility (ACRF). To facilitate the production of integrated cloud product by applying different algorithms to the ARM data streams, an advanced cloud classification algorithm was developed to classified clouds into eight types at the SGP site based on ground-based active and passive measurements. Cloud type then can be used as a guidance to select an optimal retrieval algorithm for cloud microphysical property retrieval. The ultimate goal of the effort is to develop an operational cloud classification algorithm for ARM data streams. The vision 1 IDL code of the cloud classification algorithm based on the SGP ACRF site observations was delivered to the ARM cloud translator during 2004 ARM science team meeting. Another goal of the project is to study midlevel clouds, especially mixed-phase clouds, by developing new retrieval algorithms using integrated observations at the ACRF sites. Mixed-phase clouds play a particular role in the Arctic climate system. A multiple remote sensor based algorithm, which can provide ice water content and effective size profiles, liquid water path, and layer-mean effective radius of water droplet, was developed to study arctic mixed-phase clouds. The algorithm is applied to long-term ARM observations at the NSA ACRF site. Based on these retrieval results, we are studying seasonal and interannual variations of arctic mixed-phase cloud macro- and micro-physical properties.

  20. Liquid Water Cloud Properties During the Polarimeter Definition Experiment (PODEX)

    NASA Technical Reports Server (NTRS)

    Alexandrov, Mikhail D.; Cairns, Brian; Wasilewski, Andrzei P.; Ackerman, Andrew S.; McGill, Matthew J.; Yorks, John E.; Hlavka, Dennis L.; Platnick, Steven; Arnold, George; Van Diedenhoven, Bastiaan; Chowdhary, Jacek; Ottaviani, Matteo; Knobelspiesse, Kirk D.

    2015-01-01

    We present retrievals of water cloud properties from the measurements made by the Research Scanning Polarimeter (RSP) during the Polarimeter Definition Experiment (PODEX) held between January 14 and February 6, 2013. The RSP was onboard the high-altitude NASA ER-2 aircraft based at NASA Dryden Aircraft Operation Facility in Palmdale, California. The retrieved cloud characteristics include cloud optical thickness, effective radius and variance of cloud droplet size distribution derived using a parameter-fitting technique, as well as the complete droplet size distribution function obtained by means of Rainbow Fourier Transform. Multi-modal size distributions are decomposed into several modes and the respective effective radii and variances are computed. The methodology used to produce the retrieval dataset is illustrated on the examples of a marine stratocumulus deck off California coast and stratus/fog over California's Central Valley. In the latter case the observed bimodal droplet size distributions were attributed to two-layer cloud structure. All retrieval data are available online from NASA GISS website.

  1. Cloud properties and bulk microphysical properties of semi-transparent cirrus from IR Sounders

    NASA Astrophysics Data System (ADS)

    Stubenrauch, Claudia; Feofilov, Artem; Armante, Raymond; Guignard, Anthony

    2013-04-01

    Satellite observations provide a continuous survey of the atmosphere over the whole globe. IR sounders have been observing our planet since 1979. The spectral resolution has improved from TIROS-N Operational Vertical Sounders (TOVS) to the Atmospheric InfraRed Sounder (AIRS), and to the InfraRed Atmospheric Sounding Interferometer (IASI); resolution within the CO2 absorption band makes these passive sounders most sensitive to semi-transparent cirrus (about 30% of all clouds), day and night. The LMD cloud property retrieval method developed for TOVS, has been adapted to the second generation of IR sounders like AIRS and, recently, IASI. It is based on a weighted χ2 method using different channels within the 15 micron CO2 absorption band. Once the cloud physical properties (cloud pressure and IR emissivity) are retrieved, cirrus bulk microphysical properties (De and IWP) are determined from spectral emissivity differences between 8 and 12 μm. The emissivities are determined using the retrieved cloud pressure and are then compared to those simulated by the radiative transfer model. For IASI, we use the latest version of the radiative transfer model 4A (http://4aop.noveltis.com), which has been coupled with the DISORT algorithm to take into account multiple scattering of ice crystals. The code incorporates single scattering properties of column-like or aggregate-like ice crystals provided by MetOffice (Baran et al. (2001); Baran and Francis (2004)). The synergy of AIRS and two active instruments of the A-Train (lidar and radar of the CALIPSO and CloudSat missions), which provide accurate information on vertical cloud structure, allowed the evaluation of cloud properties retrieved by the weighted χ2 method. We present first results for cloud properties obtained with IASI/ Metop-A and compare them with those of AIRS and other cloud climatologies having participated in the GEWEX cloud assessment. The combination of IASI observations at 9:30 AM and 9:30 PM complement

  2. Comparison of cloud properties between cloudsat retrievals and airplane measurements in mixed-phase cloud layers of weak convective and stratus clouds

    NASA Astrophysics Data System (ADS)

    Qiu, Yujun; Choularton, Thomas; Crosier, Jonathan; Liu, Zixia

    2015-12-01

    Cloud microphysical properties including liquid and ice particle number concentration (NC), liquid water content (LWC), ice water content (IWC) and effective radius (RE) were retrieved from CloudSat data for a weakly convective and a widespread stratus cloud. Within the mixed-phase cloud layers, liquid-phase fractions needed to be assumed in the data retrieval process, and one existing linear ( p 1) and two exponential ( p 2 and p 3) functions, which estimate the liquid-phase fraction as a function of subfreezing temperature (from -20°C to 0°C), were tested. The retrieved NC, LWC, IWC and RE using p 1 were on average larger than airplane measurements in the same cloud layer. Function p 2 performed better than p 1 or p 3 in retrieving the NCs of cloud droplets in the convective cloud, while function p 1 performed better in the stratus cloud. Function p 3 performed better in LWC estimation in both convective and stratus clouds. The REs of cloud droplets calculated using the retrieved cloud droplet NC and LWC were closer to the values of in situ observations than those retrieved directly using the p 1 function. The retrieved NCs of ice particles in both convective and stratus clouds, on the assumption of liquid-phase fraction during the retrieval of liquid droplet NCs, were closer to those of airplane observations than on the assumption of function p 1.

  3. Methods of editing cloud and atmospheric layer affected pixels from satellite data

    NASA Technical Reports Server (NTRS)

    Nixon, P. R. (Principal Investigator); Wiegand, C. L.; Richardson, A. J.; Johnson, M. P.

    1982-01-01

    Practical methods of computer screening cloud-contaminated pixels from data of various satellite systems are proposed. Examples are given of the location of clouds and representative landscape features in HCMM spectral space of reflectance (VIS) vs emission (IR). Methods of screening out cloud affected HCMM are discussed. The character of subvisible absorbing-emitting atmospheric layers (subvisible cirrus or SCi) in HCMM data is considered and radiosonde soundings are examined in relation to the presence of SCi. The statistical characteristics of multispectral meteorological satellite data in clear and SCi affected areas are discussed. Examples in TIROS-N and NOAA-7 data from several states and Mexico are presented. The VIS-IR cluster screening method for removing clouds is applied to a 262, 144 pixel HCMM scene from south Texas and northeast Mexico. The SCi that remain after cluster screening are sited out by applying a statistically determined IR limit.

  4. Probing Oort cloud and local interstellar medium properties via dust produced in cometary collisions

    SciTech Connect

    Howe, Alex R.; Rafikov, Roman R. E-mail: rrr@astro.princeton.edu

    2014-01-20

    The Oort cloud remains one of the most poorly explored regions of the solar system. We propose that its properties can be constrained by studying a population of dust grains produced in collisions of comets in the outer solar system. We explore the dynamics of μm-sized grains outside the heliosphere (beyond ∼250 AU), which are predominantly affected by the magnetic field of the interstellar medium (ISM) flow past the Sun. We derive analytic models for the production and motion of small particles as a function of their birth location in the cloud and calculate the particle flux and velocity distribution in the inner solar system. These models are verified by direct numerical simulations. We show that grains originating in the Oort cloud have a unique distribution of arrival directions, which should easily distinguish them from both interplanetary and interstellar dust populations. We also demonstrate that the distribution of particle arrival velocities is uniquely determined by the mass distribution and dust production rate in the cloud. Cometary collisions within the cloud produce a flux of μm-sized grains in the inner solar system of up to several m{sup –2} yr{sup –1}. The next generation dust detectors may be sensitive enough to detect and constrain this dust population, which will illuminate the Oort cloud's properties. We also show that the recently detected mysterious population of large (μm-sized) unbound particles, which seems to arrive with the ISM flow, is unlikely to be generated by collisions of comets in the Oort cloud.

  5. First Transmitted Hyperspectral Light Measurements and Cloud Properties from Recent Field Campaign Sampling Clouds Under Biomass Burning Aerosol

    NASA Technical Reports Server (NTRS)

    Leblanc, S.; Redemann, Jens; Shinozuka, Yohei; Flynn, Connor J.; Segal Rozenhaimer, Michal; Kacenelenbogen, Meloe Shenandoah; Pistone, Kristina Marie Myers; Schmidt, Sebastian; Cochrane, Sabrina

    2016-01-01

    We present a first view of data collected during a recent field campaign aimed at measuring biomass burning aerosol above clouds from airborne platforms. The NASA ObseRvations of CLouds above Aerosols and their intEractionS (ORACLES) field campaign recently concluded its first deployment sampling clouds and overlying aerosol layer from the airborne platform NASA P3. We present results from the Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research (4STAR), in conjunction with the Solar Spectral Flux Radiometers (SSFR). During this deployment, 4STAR sampled transmitted solar light either via direct solar beam measurements and scattered light measurements, enabling the measurement of aerosol optical thickness and the retrieval of information on aerosol particles in addition to overlying cloud properties. We focus on the zenith-viewing scattered light measurements, which are used to retrieve cloud optical thickness, effective radius, and thermodynamic phase of clouds under a biomass burning layer. The biomass burning aerosol layer present above the clouds is the cause of potential bias in retrieved cloud optical depth and effective radius from satellites. We contrast the typical reflection based approach used by satellites to the transmission based approach used by 4STAR during ORACLES for retrieving cloud properties. It is suspected that these differing approaches will yield a change in retrieved properties since light transmitted through clouds is sensitive to a different cloud volume than reflected light at cloud top. We offer a preliminary view of the implications of these differences in sampling volumes to the calculation of cloud radiative effects (CRE).

  6. FAME-C: cloud property retrieval using synergistic AATSR and MERIS observations

    NASA Astrophysics Data System (ADS)

    Carbajal Henken, C. K.; Lindstrot, R.; Preusker, R.; Fischer, J.

    2014-05-01

    A newly developed daytime cloud property retrieval algorithm FAME-C (Freie Universität Berlin AATSR MERIS Cloud) is presented. Synergistic observations from AATSR and MERIS, both mounted on the polar orbiting satellite ENVISAT, are used for cloud screening. For cloudy pixels two main steps are carried out in a sequential form. First, a micro-physical cloud property retrieval is performed using an AATSR near-infrared and visible channel. Cloud phase, cloud optical thickness, and effective radius are retrieved, and subsequently cloud water path is computed. Second, two independent cloud top height products are retrieved. For cloud top temperature AATSR brightness temperatures are used, while for cloud top pressure the MERIS oxygen-A absorption channel is used. Results from the micro-physical retrieval serve as input for the two cloud top height retrievals. Introduced are the AATSR and MERIS forward models and auxiliary data needed in FAME-C. Also, the optimal estimation method with uncertainty estimates, which also provides for uncertainty estimated of the retrieved property on a pixel-basis, is presented. Within the frame of the ESA Climate Change Initiative project first global cloud property retrievals have been conducted for the years 2007-2009. For this time period verification efforts are presented comparing FAME-C cloud micro-physical properties to MODIS-TERRA derived cloud micro-physical properties for four selected regions on the globe. The results show reasonable accuracies between the cloud micro-physical retrievals. Biases are generally smallest for marine stratocumulus clouds; -0.28, 0.41μm and -0.18 g m-2 for cloud optical thickness, effective radius and cloud water path, respectively. This is also true for the root mean square error. Also, both cloud top height products are compared to cloud top heights derived from ground-based cloud radars located at several ARM sites. FAME-C mostly shows an underestimation of cloud top heights when compared to

  7. Web-based CERES Clouds QC Property Viewing Tool

    NASA Astrophysics Data System (ADS)

    Smith, R. A.; Chu, C.; Sun-Mack, S.; Chen, Y.; Heckert, E.; Minnis, P.

    2014-12-01

    This presentation will display the capabilities of a web-based CERES cloud property viewer. Terra data will be chosen for examples. It will demonstrate viewing of cloud properties in gridded global maps, histograms, time series displays, latitudinal zonal images, binned data charts, data frequency graphs, and ISCCP plots. Images can be manipulated by the user to narrow boundaries of the map as well as color bars and value ranges, compare datasets, view data values, and more. Other atmospheric studies groups will be encouraged to put their data into the underlying NetCDF data format and view their data with the tool. A laptop will hopefully be available to allow conference attendees to try navigating the tool.

  8. Web-based CERES Clouds QC Property Viewing Tool

    NASA Astrophysics Data System (ADS)

    Smith, R. A.

    2015-12-01

    Churngwei Chu1, Rita Smith1, Sunny Sun-Mack1, Yan Chen1, Elizabeth Heckert1, Patrick Minnis21 Science Systems and Applications, Inc., Hampton, Virginia2 NASA Langley Research Center, Hampton, Virginia This presentation will display the capabilities of a web-based CERES cloud property viewer. Aqua/Terra/NPP data will be chosen for examples. It will demonstrate viewing of cloud properties in gridded global maps, histograms, time series displays, latitudinal zonal images, binned data charts, data frequency graphs, and ISCCP plots. Images can be manipulated by the user to narrow boundaries of the map as well as color bars and value ranges, compare datasets, view data values, and more. Other atmospheric studies groups will be encouraged to put their data into the underlying NetCDF data format and view their data with the tool.

  9. Multi-sensor approach to retrieving water cloud physical properties and drizzle fraction

    NASA Astrophysics Data System (ADS)

    Prianto Rusli, Stephanie; Donovan, David; Russchenberg, Herman

    2015-04-01

    Accurately representing clouds and their interaction with the surrounding matter and radiation are one of the most important factors in climate modeling. In particular, feedback processes involving low level water clouds play a significant role in determining the net effect of cloud climate forcing. An accurate description of cloud physical properties is therefore necessary to quantify these processes and their implications. To this end, measurements combined from a variety of remote sensing instruments at different wavelengths provide crucial information about the clouds. To exploit this, building upon previous work in this field, we have developed a ground-based multi-sensor retrieval algorithm within an optimal estimation framework. The inverse problem of 'translating' the radar, lidar, and microwave radiometer measurements into retrieval products is formulated in a physically consistent manner, without relying on approximate empirical proxies (such as explicit liquid water content vs radar reflectivity factor relationships). We apply the algorithm to synthetic signals based on the output of large eddy simulation model runs and present here the preliminary results. Given temperature, humidity profiles, information from the measurements, and apriori contraints, we derive the liquid water content profile. Assuming a monomodal gamma droplet size distribution, the number concentration, effective size of the cloud droplets and the extinction coefficient are computed. The retrieved profiles provide a good fit to the true ones. The algorithm is being improved to take into account the presence of drizzle, an important aspect that affects cloud lifetime. Quantifying the amount of drizzle would enable the proper use of the radar reflectivity. Further development to allow retrieval of temperature and humidity profiles as well is anticipated.

  10. A Midlatitude Cirrus Cloud Climatology from the Facility for Atmospheric Remote Sensing: Part V. Cloud Structural Properties

    SciTech Connect

    Sassen, Kenneth; Wang, Likun; Starr, David O.; Comstock, Jennifer M.; Quante, Markus

    2007-07-31

    In this fifth of a series of papers describing the extended-time high cloud observation program from the University of Utah Facility for Atmospheric Remote Sensing, the structural properties of cirrus clouds over Salt Lake City, Utah, are examined. Wavelet analysis is applied as a function of cloud height to a 10-y record of ruby (0.694 um) lidar backscattering data collected from visually-identified cirrus clouds to study the presence of periodic cloud structures, such as Kelvin-Helmholtz waves, cirrus mammata, and uncinus cells (all with wavelengths of ~1-10 km), as well as longer mesoscale cloud organizations. Approximately 8.4% (18.8%, 30.8%) of the data display such periodic structures after passing a 95% (75%, 50%) confidence level test. This may signify that most cloud organizations are quasi-periodic in nature. The amount of lidar cloud data showing periodic structures does not change considerably with length scale between 0.2 to 200 km, although a preference for ~20-km mesoscale cloud structures is indicated. Using time series of vertically-integrated lidar backscattering profiles, we find a steady decrease in autocorrelation coefficients starting at a few kilometers as the length (or model grid) scale increases. Examining the variability of cirrus cloud optical depth t from an earlier LIRAD (combined lidar and infrared radiometer) analysis reveals that the standard deviation σ of t is related by σ = 0.36 t.

  11. Cloud microphysical properties of convective clouds sampled during the Convective Precipitation Experiment (COPE) experiment.

    NASA Astrophysics Data System (ADS)

    Jackson, R.; French, J.; Leon, D.; Plummer, D. M.; Lasher-Trapp, S.; Blyth, A. M.

    2015-12-01

    The COnvective Precipitation Experiment (COPE), occurring in the southwest UK during Summer 2013, was motivated to improve quantitative precipitation forecasting, in part, with the aim to increase understanding of the warm and cold precipitation processes that can produce heavy convective rainfall in the southwest UK. In particular, we examine the creation of graupel embryos, the Hallett-Mossop process, and the effect of entrainment on these processes. To characterize the evolution of cloud microphysical properties of maturing thunderstorms, the University of Wyoming King Air sampled the tops of fresh turrets between -15 and 0. Data sampled by the Cloud Droplet Probe, Cloud Imaging grayscale Probe (CIP-Grey) and 2D Precipitation Probe during four missions are examined. Here we characterize the variability of the cloud liquid and ice particle size distributions and liquid water contents (LWC) inside updraft cores, as a function of temperature, T, and vertical velocity, w. On one of the days, the number concentration of particles with maximum dimension D > 300 μm, N>300, was less than 1 L-1, with very few ice hydrometeors observed. However, on the other missions, N>300 ranged from 1 L-1 to 250 L-1. The CIP-Grey detected liquid drops at T > -5 and a mixture of graupel and rimed columns at T < -5 for these missions, consistent with the warm rain process providing the frozen drops necessary to form graupel embryos that initiate secondary production. In general, LWC relative to adiabatic decreased from 0.75 to 0.2 with height and was lowest when N>300 > 1 L-1, consistent with precipitation growth by collision-coalescence and accretion. Finally, ice precipitation was primarily present at w < 7 m s-1 and greatest when w < 3 m s-1, suggesting that w influences the number of ice particles generated in the updraft cores sampled during COPE-MED.

  12. Sensitivity of Photolysis Frequencies and Key Tropospheric Oxidants in a Global Model to Cloud Vertical Distributions and Optical Properties

    NASA Technical Reports Server (NTRS)

    Liu, Hongyu; Crawford, James H.; Considine, David B.; Platnick, Steven; Norris, Peter M.; Duncan, Bryan N.; Pierce, Robert B.; Chen, Gao; Yantosca, Robert M.

    2009-01-01

    Clouds affect tropospheric photochemistry through modification of solar radiation that determines photolysis frequencies. As a follow-up study to our recent assessment of the radiative effects of clouds on tropospheric chemistry, this paper presents an analysis of the sensitivity of such effects to cloud vertical distributions and optical properties (cloud optical depths (CODs) and cloud single scattering albedo), in a global 3-D chemical transport model (GEOS-Chem). GEOS-Chem was driven with a series of meteorological archives (GEOS1- STRAT, GEOS-3 and GEOS-4) generated by the NASA Goddard Earth Observing System data assimilation system. Clouds in GEOS1-STRAT and GEOS-3 have more similar vertical distributions (with substantially smaller CODs in GEOS1-STRAT) while those in GEOS-4 are optically much thinner in the tropical upper troposphere. We find that the radiative impact of clouds on global photolysis frequencies and hydroxyl radical (OH) is more sensitive to the vertical distribution of clouds than to the magnitude of column CODs. With random vertical overlap for clouds, the model calculated changes in global mean OH (J(O1D), J(NO2)) due to the radiative effects of clouds in June are about 0.0% (0.4%, 0.9%), 0.8% (1.7%, 3.1%), and 7.3% (4.1%, 6.0%), for GEOS1-STRAT, GEOS-3 and GEOS-4, respectively; the geographic distributions of these quantities show much larger changes, with maximum decrease in OH concentrations of approx.15-35% near the midlatitude surface. The much larger global impact of clouds in GEOS-4 reflects the fact that more solar radiation is able to penetrate through the optically thin upper-tropospheric clouds, increasing backscattering from low-level clouds. Model simulations with each of the three cloud distributions all show that the change in the global burden of ozone due to clouds is less than 5%. Model perturbation experiments with GEOS-3, where the magnitude of 3-D CODs are progressively varied from -100% to 100%, predict only modest

  13. Sensitivity of photolysis frequencies and key tropospheric oxidants in a global model to cloud vertical distributions and optical properties

    NASA Astrophysics Data System (ADS)

    Liu, Hongyu; Crawford, James H.; Considine, David B.; Platnick, Steven; Norris, Peter M.; Duncan, Bryan N.; Pierce, Robert B.; Chen, Gao; Yantosca, Robert M.

    2009-05-01

    Clouds directly affect tropospheric photochemistry through modification of solar radiation that determines photolysis frequencies. As a follow-up study to our recent assessment of these direct radiative effects of clouds on tropospheric chemistry, this paper presents an analysis of the sensitivity of such effects to cloud vertical distributions and optical properties (cloud optical depths (CODs) and cloud single scattering albedo), in a global three-dimensional (3-D) chemical transport model. The model was driven with a series of meteorological archives (GEOS-1 in support of the Stratospheric Tracers of Atmospheric Transport mission, or GEOS1-STRAT, GEOS-3, and GEOS-4) generated by the NASA Goddard Earth Observing System (GEOS) data assimilation system. Clouds in GEOS1-STRAT and GEOS-3 have more similar vertical distributions (with substantially smaller CODs in GEOS1-STRAT) while those in GEOS-4 are optically much thinner in the tropical upper troposphere. We find that the radiative impact of clouds on global photolysis frequencies and hydroxyl radical (OH) is more sensitive to the vertical distribution of clouds than to the magnitude of column CODs. With random vertical overlap for clouds, the model calculated changes in global mean OH (J(O1D), J(NO2)) due to the radiative effects of clouds in June are about 0.0% (0.4%, 0.9%), 0.8% (1.7%, 3.1%), and 7.3% (4.1%, 6.0%) for GEOS1-STRAT, GEOS-3, and GEOS-4, respectively; the geographic distributions of these quantities show much larger changes, with maximum decrease in OH concentrations of ˜15-35% near the midlatitude surface. The much larger global impact of clouds in GEOS-4 reflects the fact that more solar radiation is able to penetrate through the optically thin upper tropospheric clouds, increasing backscattering from low-level clouds. Model simulations with each of the three cloud distributions all show that the change in the global burden of ozone due to clouds is less than 5%. Model perturbation experiments

  14. Some physical and thermodynamic properties of rocket exhaust clouds measured with infrared scanners

    NASA Technical Reports Server (NTRS)

    Gomberg, R. I.; Kantsios, A. G.; Rosensteel, F. J.

    1977-01-01

    Measurements using infrared scanners were made of the radiation from exhaust clouds from liquid- and solid-propellant rocket boosters. Field measurements from four launches were discussed. These measurements were intended to explore the physical and thermodynamic properties of these exhaust clouds during their formation and subsequent dispersion. Information was obtained concerning the initial cloud's buoyancy, the stabilized cloud's shape and trajectory, the cloud volume as a function of time, and it's initial and stabilized temperatures. Differences in radiation intensities at various wavelengths from ambient and stabilized exhaust clouds were investigated as a method of distinguishing between the two types of clouds. The infrared remote sensing method used can be used at night when visible range cameras are inadequate. Infrared scanning techniques developed in this project can be applied directly to natural clouds, clouds containing certain radionuclides, or clouds of industrial pollution.

  15. The interpretation of remotely sensed cloud properties from a model paramterization perspective

    NASA Technical Reports Server (NTRS)

    HARSHVARDHAN; Wielicki, Bruce A.; Ginger, Kathryn M.

    1994-01-01

    A study has been made of the relationship between mean cloud radiative properties and cloud fraction in stratocumulus cloud systems. The analysis is of several Land Resources Satellite System (LANDSAT) images and three hourly International Satellite Cloud Climatology Project (ISCCP) C-1 data during daylight hours for two grid boxes covering an area typical of a general circulation model (GCM) grid increment. Cloud properties were inferred from the LANDSAT images using two thresholds and several pixel resolutions ranging from roughly 0.0625 km to 8 km. At the finest resolution, the analysis shows that mean cloud optical depth (or liquid water path) increases somewhat with increasing cloud fraction up to 20% cloud coverage. More striking, however, is the lack of correlation between the two quantities for cloud fractions between roughly 0.2 and 0.8. When the scene is essentially overcast, the mean cloud optical tends to be higher. Coarse resolution LANDSAT analysis and the ISCCP 8-km data show lack of correlation between mean cloud optical depth and cloud fraction for coverage less than about 90%. This study shows that there is perhaps a local mean liquid water path (LWP) associated with partly cloudy areas of stratocumulus clouds. A method has been suggested to use this property to construct the cloud fraction paramterization in a GCM when the model computes a grid-box-mean LWP.

  16. The interpretation of remotely sensed cloud properties from a model paramterization perspective

    SciTech Connect

    Harshvardhan; Wielicki, B.A.; Ginger, K.M. |

    1994-12-01

    A study has been made of the relationship between mean cloud radiative properties and cloud fraction in stratocumulus cloud systems. The analysis is of several Land Resources Satellite System (LANDSAT) images and three hourly International Satellite Cloud Climatology Project (ISCCP) C-1 data during daylight hours for two grid boxes covering an area typical of a general circulation model (GCM) grid increment. Cloud properties were inferred from the LANDSAT images using two thresholds and several pixel resolutions ranging from roughly 0.0625 km to 8 km. At the finest resolution, the analysis shows that mean cloud optical depth (or liquid water path) increases somewhat with increasing cloud fraction up to 20% cloud coverage. More striking, however, is the lack of correlation between the two quantities for cloud fractions between roughly 0.2 and 0.8. When the scene is essentially overcast, the mean cloud optical tends to be higher. Coarse resolution LANDSAT analysis and the ISCCP 8-km data show lack of correlation between mean cloud optical depth and cloud fraction for coverage less than about 90%. This study shows that there is perhaps a local mean liquid water path (LWP) associated with partly cloudy areas of stratocumulus clouds. A method has been suggested to use this property to construct the cloud fraction paramterization in a GCM when the model computes a grid-box-mean LWP.

  17. Ground Based Retrievals of Cloud Properties for Liquid, Glaciated and Mixed Phase Conditions

    NASA Astrophysics Data System (ADS)

    Mishra, S.; Mitchell, D. L.; Deslover, D.

    2008-12-01

    provides one estimate of the LWP/TWP fraction. Another estimate is obtained by applying the principle of photon tunneling or wave resonance to radiances at 11 and 12 μm, which allows us to infer the magnitude or absence of a small mode for the retrieved PSD. Combining this small mode information with the PSD scheme describing the larger ice particle concentrations yields the retrieved PSD. While this is a work in progress, the anticipated products from this AERI-radar retrieval scheme are the IWP/IWC, LWP/TWP fraction, and LWP for mixed phase clouds and IWP/IWC, PSD slope and effective diameter for cirrus clouds. This information can be extremely useful in characterizing cloud microphysical propertied in Global Climate Models (GCMs). For example, Arctic clouds are often mixed phase and play a major role in Arctic climate, and need to be characterized in GCMs. Moreover, the PSD slope can be used to estimate ice sedimentation rates, a critical parameter affecting cirrus cloud lifetime, IWP and coverage. The fact that (1) IWP retrieved from the MMCR radar was generally consistent with the AERI TWP in glaciated regions and that (2) these retrievals were independent and based on very different physics appears promising for using this approach to approximate IWP and LWP in mixed phase clouds. This technique appears particularly useful for characterization of liquid and mixed phase clouds having TWP < 100 gm-2, a range where traditional methods have exhibited insufficient accuracy.

  18. Retrieval of radiative and microphysical properties of clouds from multispectral infrared measurements

    NASA Astrophysics Data System (ADS)

    Iwabuchi, Hironobu; Saito, Masanori; Tokoro, Yuka; Putri, Nurfiena Sagita; Sekiguchi, Miho

    2016-12-01

    Satellite remote sensing of the macroscopic, microphysical, and optical properties of clouds are useful for studying spatial and temporal variations of clouds at various scales and constraining cloud physical processes in climate and weather prediction models. Instead of using separate independent algorithms for different cloud properties, a unified, optimal estimation-based cloud retrieval algorithm is developed and applied to moderate resolution imaging spectroradiometer (MODIS) observations using ten thermal infrared bands. The model considers sensor configurations, background surface and atmospheric profile, and microphysical and optical models of ice and liquid cloud particles and radiative transfer in a plane-parallel, multilayered atmosphere. Measurement and model errors are thoroughly quantified from direct comparisons of clear-sky observations over the ocean with model calculations. Performance tests by retrieval simulations show that ice cloud properties are retrieved with high accuracy when cloud optical thickness (COT) is between 0.1 and 10. Cloud-top pressure is inferred with uncertainty lower than 10 % when COT is larger than 0.3. Applying the method to a tropical cloud system and comparing the results with the MODIS Collection 6 cloud product shows good agreement for ice cloud optical thickness when COT is less than about 5. Cloud-top height agrees well with estimates obtained by the CO2 slicing method used in the MODIS product. The present algorithm can detect optically thin parts at the edges of high clouds well in comparison with the MODIS product, in which these parts are recognized as low clouds by the infrared window method. The cloud thermodynamic phase in the present algorithm is constrained by cloud-top temperature, which tends not to produce results with an ice cloud that is too warm and liquid cloud that is too cold.

  19. Factors Affecting University Students' Intention to Use Cloud Computing in Jordan

    ERIC Educational Resources Information Center

    Rababah, Khalid Ali; Khasawneh, Mohammad; Nassar, Bilal

    2017-01-01

    The aim of this study is to examine the factors affecting students' intention to use cloud computing in the Jordanian universities. To achieve this purpose, a quantitative research approach which is a survey-based was deployed. Around 400 questionnaires were distributed randomly to Information Technology (IT) students at four universities in…

  20. A CloudSat-CALIPSO View of Cloud and Precipitation Properties Across Cold Fronts over the Global Oceans

    NASA Technical Reports Server (NTRS)

    Naud, Catherine M.; Posselt, Derek J.; van den Heever, Susan C.

    2015-01-01

    The distribution of cloud and precipitation properties across oceanic extratropical cyclone cold fronts is examined using four years of combined CloudSat radar and CALIPSO lidar retrievals. The global annual mean cloud and precipitation distributions show that low-level clouds are ubiquitous in the post frontal zone while higher-level cloud frequency and precipitation peak in the warm sector along the surface front. Increases in temperature and moisture within the cold front region are associated with larger high-level but lower mid-/low level cloud frequencies and precipitation decreases in the cold sector. This behavior seems to be related to a shift from stratiform to convective clouds and precipitation. Stronger ascent in the warm conveyor belt tends to enhance cloudiness and precipitation across the cold front. A strong temperature contrast between the warm and cold sectors also encourages greater post-cold-frontal cloud occurrence. While the seasonal contrasts in environmental temperature, moisture, and ascent strength are enough to explain most of the variations in cloud and precipitation across cold fronts in both hemispheres, they do not fully explain the differences between Northern and Southern Hemisphere cold fronts. These differences are better explained when the impact of the contrast in temperature across the cold front is also considered. In addition, these large-scale parameters do not explain the relatively large frequency in springtime post frontal precipitation.

  1. Intercomparisons of marine boundary layer cloud properties from the ARM CAP-MBL campaign and two MODIS cloud products

    NASA Astrophysics Data System (ADS)

    Zhang, Zhibo; Dong, Xiquan; Xi, Baike; Song, Hua; Ma, Po-Lun; Ghan, Steven J.; Platnick, Steven; Minnis, Patrick

    2017-02-01

    From April 2009 to December 2010, the Department of Energy Atmospheric Radiation Measurement (ARM) program carried out an observational field campaign on Graciosa Island, targeting the marine boundary layer (MBL) clouds over the Azores region. In this paper, we present an intercomparison of the MBL cloud properties, namely, cloud liquid water path (LWP), cloud optical thickness (COT), and cloud-droplet effective radius (CER), among retrievals from the ARM mobile facility and two Moderate Resolution Imaging Spectroradiometer (MODIS) cloud products (Goddard Space Flight Center (GSFC)-MODIS and Clouds and Earth's Radiant Energy System-MODIS). A total of 63 daytime single-layer MBL cloud cases are selected for intercomparison. Comparison of collocated retrievals indicates that the two MODIS cloud products agree well on both COT and CER retrievals, with the correlation coefficient R > 0.95, despite their significant difference in spatial sampling. In both MODIS products, the CER retrievals based on the 2.1 µm band (CER2.1) are significantly larger than those based on the 3.7 µm band (CER3.7). The GSFC-MODIS cloud product is collocated and compared with ground-based ARM observations at several temporal-spatial scales. In general, the correlation increases with more precise collocation. For the 63 selected MBL cloud cases, the GSFC-MODIS LWP and COT retrievals agree reasonably well with the ground-based observations with no apparent bias and correlation coefficient R around 0.85 and 0.70, respectively. However, GSFC-MODIS CER3.7 and CER2.1 retrievals have a lower correlation (R 0.5) with the ground-based retrievals. For the 63 selected cases, they are on average larger than ground observations by about 1.5 µm and 3.0 µm, respectively. Taking into account that the MODIS CER retrievals are only sensitive to cloud top reduces the bias only by 0.5 µm.

  2. Macrophysical and optical properties of midlatitude cirrus clouds from four ground-based lidars and collocated CALIOP observations

    SciTech Connect

    Dupont, Jean-Charles; Haeffelin, M.; Morille, Y.; Noel, V.; Keckhut, P.; Winker, D.; Comstock, Jennifer M.; Chervet, P.; Roblin, A.

    2010-05-27

    Ground-based lidar and CALIOP datasets gathered over four mid-latitude sites, two US and two French sites, are used to evaluate the consistency of cloud macrophysical and optical property climatologies that can be derived by such datasets. The consistency in average cloud height (both base and top height) between the CALIOP and ground datasets ranges from -0.4km to +0.5km. The cloud geometrical thickness distributions vary significantly between the different datasets, due in part to the original vertical resolutions of the lidar profiles. Average cloud geometrical thicknesses vary from 1.2 to 1.9km, i.e. by more than 50%. Cloud optical thickness distributions in subvisible, semi-transparent and moderate intervals differ by more than 50% between ground and space-based datasets. The cirrus clouds with 2 optical thickness below 0.1 (not included in historical cloud climatologies) represent 30-50% of the non-opaque cirrus class. The differences in average cloud base altitude between ground and CALIOP datasets of 0.0-0.1 km, 0.0-0.2 km and 0.0-0.2 km can be attributed to irregular sampling of seasonal variations in the ground-based data, to day-night differences in detection capabilities by CALIOP, and to the restriction to situations without low-level clouds in ground-based data, respectively. The cloud geometrical thicknesses are not affected by irregular sampling of seasonal variations in the ground-based data, while up to 0.0-0.2 km and 0.1-0.3 km differences can be attributed to day-night differences in detection capabilities by CALIOP, and to the restriction to situations without lowlevel clouds in ground-based data, respectively.

  3. Optical properties of marine stratocumulus clouds modified by ship track effluents

    NASA Technical Reports Server (NTRS)

    King, Michael D.; Nakajima, Teruyuki; Radke, Lawrence F.

    1990-01-01

    Results are presented from multispectral radiation measurements made within a marine stratocumulus cloud layer modified by ship-track effluents. The measurements showed that, compared with nearby noncontaminated clouds not affected by pollution, the upwelling intensity field of the modified stratocumulus clouds increased at a nonabsorbing wavelength in the visible region and decreased in the NIR, where absorption by liquid water is significant. The observations are consistent with an increased optical thickness, a reduced effective radius of the cloud droplets, and a reduced absorption in the contaminated cloud layer compared to a noncontaminated cloud.

  4. Masses, Radii, and Cloud Properties of the HR 8799 Planets

    NASA Technical Reports Server (NTRS)

    Marley, Mark S.; Saumon, Didier; Cushing, Michael; Ackerman, Andrew S.; Fortney, Jonathan J.; Freedman, Richard

    2012-01-01

    The near-infrared colors of the planets directly imaged around the A star HR 8799 are much redder than most field brown dwarfs of the same effective temperature. Previous theoretical studies of these objects have compared the photometric and limited spectral data of the planets to the predictions of various atmosphere and evolution models and concluded that the atmospheres of planets b, c, and d are unusually cloudy or have unusual cloud properties. Most studies have also found that the inferred radii of some or all of the planets disagree with expectations of standard giant planet evolution models. Here we compare the available data to the predictions of our own set of atmospheric and evolution models that have been extensively tested against field L and T dwarfs, including the reddest L dwarfs. Unlike almost all previous studies we specify mutually self-consistent choices for effective temperature, gravity, cloud properties, and planetary radius. This procedure yields plausible and self-consistent values for the masses, effective temperatures, and cloud properties of all three planets. We find that the cloud properties of the HR 8799 planets are in fact not unusual but rather follow previously recognized trends including a gravity dependence on the temperature of the L to T spectral transition, some reasons for which we discuss. We find that the inferred mass of planet b is highly sensitive to the H and K band spectrum. Solutions for planets c and particularly d are less certain but are consistent with the generally accepted constraints on the age of the primary star and orbital dynamics. We also confirm that as for L and T dwarfs and solar system giant planets, non-equilibrium chemistry driven by atmospheric mixing is also important for these objects. Given the preponderance of data suggesting that the L to T spectral type transition is gravity dependent, we present a new evolution calculation that predicts cooling tracks on the near-infrared color

  5. FAME-C: cloud property retrieval using synergistic AATSR and MERIS observations

    NASA Astrophysics Data System (ADS)

    Carbajal Henken, C. K.; Lindstrot, R.; Preusker, R.; Fischer, J.

    2014-11-01

    A newly developed daytime cloud property retrieval algorithm, FAME-C (Freie Universität Berlin AATSR MERIS Cloud), is presented. Synergistic observations from the Advanced Along-Track Scanning Radiometer (AATSR) and the Medium Resolution Imaging Spectrometer (MERIS), both mounted on the polar-orbiting Environmental Satellite (Envisat), are used for cloud screening. For cloudy pixels two main steps are carried out in a sequential form. First, a cloud optical and microphysical property retrieval is performed using an AATSR near-infrared and visible channel. Cloud phase, cloud optical thickness, and effective radius are retrieved, and subsequently cloud water path is computed. Second, two cloud top height products are retrieved based on independent techniques. For cloud top temperature, measurements in the AATSR infrared channels are used, while for cloud top pressure, measurements in the MERIS oxygen-A absorption channel are used. Results from the cloud optical and microphysical property retrieval serve as input for the two cloud top height retrievals. Introduced here are the AATSR and MERIS forward models and auxiliary data needed in FAME-C. Also, the optimal estimation method, which provides uncertainty estimates of the retrieved property on a pixel basis, is presented. Within the frame of the European Space Agency (ESA) Climate Change Initiative (CCI) project, the first global cloud property retrievals have been conducted for the years 2007-2009. For this time period, verification efforts are presented, comparing, for four selected regions around the globe, FAME-C cloud optical and microphysical properties to cloud optical and microphysical properties derived from measurements of the Moderate Resolution Imaging Spectroradiometer (MODIS) on the Terra satellite. The results show a reasonable agreement between the cloud optical and microphysical property retrievals. Biases are generally smallest for marine stratocumulus clouds: -0.28, 0.41 μm and -0.18 g m-2 for

  6. Marine Boundary Layer Cloud Properties From AMF Point Reyes Satellite Observations

    NASA Technical Reports Server (NTRS)

    Jensen, Michael; Vogelmann, Andrew M.; Luke, Edward; Minnis, Patrick; Miller, Mark A.; Khaiyer, Mandana; Nguyen, Louis; Palikonda, Rabindra

    2007-01-01

    Cloud Diameter, C(sub D), offers a simple measure of Marine Boundary Layer (MBL) cloud organization. The diurnal cycle of cloud-physical properties and C(sub D) at Pt Reyes are consistent with previous work. The time series of C(sub D) can be used to identify distinct mesoscale organization regimes within the Pt. Reyes observation period.

  7. ISCCP Cloud Properties Associated with Standard Cloud Types Identified in Individual Surface Observations

    NASA Technical Reports Server (NTRS)

    Hahn, Carole J.; Rossow, William B.; Warren, Stephen G.

    1999-01-01

    Individual surface weather observations from land stations and ships are compared with individual cloud retrievals of the International Satellite Cloud Climatology Project (ISCCP), Stage C1, for an 8-year period (1983-1991) to relate cloud optical thicknesses and cloud-top pressures obtained from satellite data to the standard cloud types reported in visual observations from the surface. Each surface report is matched to the corresponding ISCCP-C1 report for the time of observation for the 280x280-km grid-box containing that observation. Classes of the surface reports are identified in which a particular cloud type was reported present, either alone or in combination with other clouds. For each class, cloud amounts from both surface and C1 data, base heights from surface data, and the frequency-distributions of cloud-top pressure (p(sub c) and optical thickness (tau) from C1 data are averaged over 15-degree latitude zones, for land and ocean separately, for 3-month seasons. The frequency distribution of p(sub c) and tau is plotted for each of the surface-defined cloud types occurring both alone and with other clouds. The average cloud-top pressures within a grid-box do not always correspond well with values expected for a reported cloud type, particularly for the higher clouds Ci, Ac, and Cb. In many cases this is because the satellites also detect clouds within the grid-box that are outside the field of view of the surface observer. The highest average cloud tops are found for the most extensive cloud type, Ns, averaging 7 km globally and reaching 9 km in the ITCZ. Ns also has the greatest average retrieved optical thickness, tau approximately equal 20. Cumulonimbus clouds may actually attain far greater heights and depths, but do not fill the grid-box. The tau-p(sub c) distributions show features that distinguish the high, middle, and low clouds reported by the surface observers. However, the distribution patterns for the individual low cloud types (Cu, Sc, St

  8. Assimilation of Cloud- and Land-affected TOVS/ATOVS Level 1b data at DAO

    NASA Technical Reports Server (NTRS)

    Joiner, Joanna; Frank, Donald; daSilva, Arlindo; Bosilovich, Mike; Radacovich, Jon; Atlas, Robert (Technical Monitor)

    2002-01-01

    Despite significant advances in the assimilation of TIROS Operational Vertical Sounder/Advanced TIROS Operational Vertical Sounder (TOVS)/(ATOVS) data over the last decade, there are still many unresolved issues. For example, at several centers, cloud-and land-affected TOVS data are not assimilated. In this study, we show positive impact from the use of cloud cleared and land-affected TOVS data in the NASA Data Assimilation Office's (DAO) Finite Volume Data Assimilation System (fv-DAS). We will discuss how treatment of TOVS data affects the stratosphere and tropopause in the fvDAS. We will also describe the use of TOVS data for land-surface analysis and assimilation and other developments regarding the use of TOVS data at the DAO.

  9. [Radiative Properties of Cirrus Clouds Based on Hexagonal and Spherical Ice Crystals Models].

    PubMed

    Husltu; Bao, Yu-hai; Xu, Jian; Qing, Song; Bao, Gang

    2015-05-01

    Single scattering properties for spherical and hexagonal ice crystal models with different size parameters and wavelengths were employed to calculate satellite observed radiation and downward flux in ground surface using RSTAR radiative transfer model. Results indicated that simulated satellite observed radiation and ground surface downward radiant flux from different shapes of ice crystal models were different. The difference in the spectral radiation fluxes between 0. 4 and 1. 0 µm was largest, and particle shapes affected the downward radiant flux significantly. It was verified that the proper selection of the effective ice crystal model is not only important for retrieval of the microphysical and optical parameters of the cirrus cloud, but also important for obtaining the radiant flux on the earth's surface correctly. These results are important for retrieving cloud microphysical parameters and simulation of the ground surface downward radiant flux.

  10. Microphysical Properties of Clouds with Low Liquid Water Paths: An Update from Clouds with Low Optical (Water) Depth

    SciTech Connect

    Turner, D.D.; Flynn, C.; Long, C.; McFarlane, S.; Vogelmann, A.; Johnson, K.; Miller, M.; Chiu, C.; Marshak, A.; Wiscombe, W.; Clough, S.A.; Heck, P.; Minnis, P.; Liljegren, J.; Min, Q.; O'Hirok, W.; Wang, Z.

    2005-03-18

    Clouds play a critical role in the modulation of the radiative transfer in the atmosphere, and how clouds interact with radiation is one of the primary uncertainties in global climate models (GCMs). To reduce this uncertainty, the U.S. Department of Energy's Atmospheric Radiation Measurement (ARM) program collects an immense amount of data from its Climate Research Facilities (CRFs); these data include observations of radiative fluxes, cloud properties from active and passive remote sensors, upper atmospheric soundings, and other observations. The program's goal is to use these coincident, longterm observations to improve the parameterization of radiative transfer in clear and cloudy atmospheres in GCMs.

  11. Springtime cloud properties in the Taiwan Strait: synoptic controls and local processes

    NASA Astrophysics Data System (ADS)

    Kueh, Mien-Tze; Lin, Pay-Liam

    2014-05-01

    This paper examines the springtime cloud properties in the Taiwan Strait (TS), with emphases on their dependence on synoptic controls and local processes, using a suite of in situ and remote sensing observations. Cloud properties in the TS are inferred from a combination of MODIS and in situ observations and further classified into two synoptic conditions: continental cold air surge and frontal system. The study reveals a predominance of synoptic-scale controls in regulating the cloud properties in the TS. The sensitivity of clouds to the local thermodynamic mechanisms as well as the underlying surface conditions is fundamentally dependent on synoptic-scale flow patterns. The springtime clouds over the TS are commonly a mixture of stratocumulus and alto clouds. More precisely, there is a preponderance of stratocumulus over the strait. A preferential occupancy of stratiform alto clouds is recognized during cold air surge, whereas vertical development of cloud layers (mostly the stratocumulus) is commonly observed with frontal passage. The most distinct difference between the local clouds formation associated with the two synoptic conditions is the suppression of very low cloud and fog along with cold air surge. Stratus clouds and fog are present within the northward prefrontal airflow from warmer to colder water sites, along with an increase in stability relating to lower altitudes of boundary layer clouds. Although the rainfall occurrences are about the same for both synoptic conditions, the frontal rain amounts are larger on average.

  12. Development of EarthCARE/MSI ice and water cloud properties products

    NASA Astrophysics Data System (ADS)

    Takagi, S.; Nagao, T. M.; Ishida, H.; Letu, H.; Hashimoto, M.; Nakajima, T. Y.

    2015-12-01

    Clouds and aerosols are the major uncertainty in the understanding of the Earth's climate system. An improvement of understanding and better modeling of the relationship of clouds, aerosols and radiation are therefore prominent part in climate research and weather prediction. It is important to obtain the global data of clouds and aerosols occurrence, structure and physical properties that are derived from measurements of solar and thermal radiation. EarthCARE (Earth Clouds, Aerosols and Radiation Explorer) is one of the future earth observation mission of ESA and JAXA. The satellite will carry four instruments for observation of clouds and aerosols; Atmospheric Lidar (ATLID), Cloud Profiling Rader (CPR), Multi-Spectral Imager (MSI), and Broad-Band Radiometer (BBR). This mission aims at understanding of the role that clouds and aerosols play in reflecting incident solar radiation back into space and trapping infrared radiation emitted from Earth's surface. These observations are needed to improve the precision of climate variability prediction. MSI provides across-track information on cloud with channels in the visible, near infrared, shortwave and thermal infrared. Water cloud optical properties are derived in using EarthCARE/MSI standard product based on CLAUDIA [Ishida and Nakajima, 2009] and CAPCOM [Nakajima and Nakajima, 1995; Kawamoto et al., 2001]. Research product based on MWP method [M. Hashimoto, 2015. PhD Thesis] is advanced to obtain the ice cloud optical properties. In this presentation, development of the products and retrieved cloud properties will be introduced.

  13. Cloud Properties of CERES-MODIS Edition 4 and CERES-VIIRS Edition 1

    NASA Technical Reports Server (NTRS)

    Sun-Mack, Sunny; Minnis, Patrick; Chang, Fu-Lung; Hong, Gang; Arduini, Robert; Chen, Yan; Trepte, Qing; Yost, Chris; Smith, Rita; Brown, Ricky; Chu, Churngwei; Heckert, Elizabeth; Gibson, Sharon; Heck, Patrick W.

    2015-01-01

    The Clouds and Earth's Radiant Energy System (CERES) analyzes MODerate-resolution Imaging Spectroradiometer (MODIS) data and Visible Infrared Imaging Radiometer Suite (VIIRS) to derive cloud properties that are combine with aerosol and CERES broadband flux data to create a multi-parameter data set for climate study. CERES has produced over 15 years of data from Terra and over 13 years of data from Aqua using the CERES-MODIS Edition-2 cloud retrieval algorithm. A recently revised algorithm, CERESMODIS Edition 4, has been developed and is now generating enhanced cloud data for climate research (over 10 years for Terra and 8 years for Aqua). New multispectral retrievals of properties are included along with a multilayer cloud retrieval system. Cloud microphysical properties are reported at 3 wavelengths, 0.65, 1.24, and 2.1 microns to enable better estimates of the vertical profiles of cloud water contents. Cloud properties over snow are retrieved using the 1.24-micron channel. A new CERES-VIIRS cloud retrieval package was developed for the VIIRS spectral complement and is currently producing the CERES-VIIRS Edition 1 cloud dataset. The results from CERES-MODIS Edition 4 and CERES-VIIRS Edition 1 are presented and compared with each other and other datasets, including CALIPSO, CloudSat and the CERES-MODIS Edition-2 results.

  14. Retrievals of cloud microphysical properties from the Research Scanning Polarimeter measurements made during PODEX field campaign

    NASA Astrophysics Data System (ADS)

    Alexandrov, M. D.; Cairns, B.; Sinclair, K.

    2013-12-01

    We present the retrievals of cloud droplet size distribution parameters (effective radius and variance) from the Research Scanning Polarimeter (RSP) measurements made during NASA's POlarimeter Definition EXperiment (PODEX), which was based in Palmdale, California in January - February 2013. The RSP is an airborne prototype for the Aerosol Polarimetery Sensor (APS), which was built for the NASA Glory Mission project. This instrument measures both polarized and total reflectances in 9 spectral channels with center wavelengths of 410, 470, 555, 670, 865, 960, 1590, 1880 and 2250 nm. The RSP is a push broom scanner making samples at 0.8 degree intervals within 60 degrees from nadir in both forward and backward directions. The data from actual RSP scans is aggregated into "virtual" scans, each consisting of all reflectances (at a variety of scattering angles) from a single point on the ground or at the cloud top. In the case of water clouds the rainbow is observed in the polarized reflectances in the scattering angle range between 135 and 170 degrees. It has a unique signature that is being used to accurately determine the droplet size and is not affected by cloud morphology. Simple parametric fitting algorithm applied to these polarized reflectances provides retrievals of the droplet effective radius and variance assuming a prescribed size distribution shape (gamma distribution). In addition to this, we use a non-parametric method, Rainbow Fourier Transform (RFT), which allows to retrieve the droplet size distribution a parametric model. Of particular interest is the information contained in droplet size distribution width, which is indicative of cloud life cycle. The absorbing band method is also applied to RSP total reflectance observations. The difference in the retrieved droplet size between polarized and absorbing band techniques is expected to reflect the strength of the vertical gradient in cloud liquid water content. In addition to established retrieval

  15. Reprint of "How do components of real cloud water affect aqueous pyruvate oxidation?"

    NASA Astrophysics Data System (ADS)

    Boris, Alexandra J.; Desyaterik, Yury; Collett, Jeffrey L.

    2015-01-01

    Chemical oxidation of dissolved volatile or semi-volatile organic compounds within fog and cloud droplets in the atmosphere could be a major pathway for secondary organic aerosol (SOA) formation. This proposed pathway consists of: (1) dissolution of organic chemicals from the gas phase into a droplet; (2) reaction with an aqueous phase oxidant to yield low volatility products; and (3) formation of particle phase organic matter as the droplet evaporates. The common approach to simulating aqueous SOA (aqSOA) reactions is photo-oxidation of laboratory standards in pure water. Reactions leading to aqSOA formation should be studied within real cloud and fog water to determine whether additional competing processes might alter apparent rates of reaction as indicated by rates of reactant loss or product formation. To evaluate and identify the origin of any cloud water matrix effects on one example of observed aqSOA production, pyruvate oxidation experiments simulating aqSOA formation were monitored within pure water, real cloud water samples, and an aqueous solution of inorganic salts. Two analysis methods were used: online electrospray ionization high-resolution time-of-flight mass spectrometry (ESI-HR-ToF-MS), and offline anion exchange chromatography (IC) with quantitative conductivity and qualitative ESI-HR-ToF-MS detection. The apparent rate of oxidation of pyruvate was slowed in cloud water matrices: overall measured degradation rates of pyruvate were lower than in pure water. This can be at least partially accounted for by the observed formation of pyruvate from reactions of other cloud water components. Organic constituents of cloud water also compete for oxidants and/or UV light, contributing to the observed slowed degradation rates of pyruvate. The oxidation of pyruvate was not significantly affected by the presence of inorganic anions (nitrate and sulfate) at cloud-relevant concentrations. Future bulk studies of aqSOA formation reactions using simplified

  16. How do components of real cloud water affect aqueous pyruvate oxidation?

    NASA Astrophysics Data System (ADS)

    Boris, Alexandra J.; Desyaterik, Yury; Collett, Jeffrey L.

    2014-06-01

    Chemical oxidation of dissolved volatile or semi-volatile organic compounds within fog and cloud droplets in the atmosphere could be a major pathway for secondary organic aerosol (SOA) formation. This proposed pathway consists of: (1) dissolution of organic chemicals from the gas phase into a droplet; (2) reaction with an aqueous phase oxidant to yield low volatility products; and (3) formation of particle phase organic matter as the droplet evaporates. The common approach to simulating aqueous SOA (aqSOA) reactions is photo-oxidation of laboratory standards in pure water. Reactions leading to aqSOA formation should be studied within real cloud and fog water to determine whether additional competing processes might alter apparent rates of reaction as indicated by rates of reactant loss or product formation. To evaluate and identify the origin of any cloud water matrix effects on one example of observed aqSOA production, pyruvate oxidation experiments simulating aqSOA formation were monitored within pure water, real cloud water samples, and an aqueous solution of inorganic salts. Two analysis methods were used: online electrospray ionization high-resolution time-of-flight mass spectrometry (ESI-HR-ToF-MS), and offline anion exchange chromatography (IC) with quantitative conductivity and qualitative ESI-HR-ToF-MS detection. The apparent rate of oxidation of pyruvate was slowed in cloud water matrices: overall measured degradation rates of pyruvate were lower than in pure water. This can be at least partially accounted for by the observed formation of pyruvate from reactions of other cloud water components. Organic constituents of cloud water also compete for oxidants and/or UV light, contributing to the observed slowed degradation rates of pyruvate. The oxidation of pyruvate was not significantly affected by the presence of inorganic anions (nitrate and sulfate) at cloud-relevant concentrations. Future bulk studies of aqSOA formation reactions using simplified

  17. Ten Years of Cloud Properties from MODIS: Global Statistics and Use in Climate Model Evaluation

    NASA Technical Reports Server (NTRS)

    Platnick, Steven E.

    2011-01-01

    The NASA Moderate Resolution Imaging Spectroradiometer (MODIS), launched onboard the Terra and Aqua spacecrafts, began Earth observations on February 24, 2000 and June 24,2002, respectively. Among the algorithms developed and applied to this sensor, a suite of cloud products includes cloud masking/detection, cloud-top properties (temperature, pressure), and optical properties (optical thickness, effective particle radius, water path, and thermodynamic phase). All cloud algorithms underwent numerous changes and enhancements between for the latest Collection 5 production version; this process continues with the current Collection 6 development. We will show example MODIS Collection 5 cloud climatologies derived from global spatial . and temporal aggregations provided in the archived gridded Level-3 MODIS atmosphere team product (product names MOD08 and MYD08 for MODIS Terra and Aqua, respectively). Data sets in this Level-3 product include scalar statistics as well as 1- and 2-D histograms of many cloud properties, allowing for higher order information and correlation studies. In addition to these statistics, we will show trends and statistical significance in annual and seasonal means for a variety of the MODIS cloud properties, as well as the time required for detection given assumed trends. To assist in climate model evaluation, we have developed a MODIS cloud simulator with an accompanying netCDF file containing subsetted monthly Level-3 statistical data sets that correspond to the simulator output. Correlations of cloud properties with ENSO offer the potential to evaluate model cloud sensitivity; initial results will be discussed.

  18. The interpretation of remotely sensed cloud properties from a model parameterization perspective

    SciTech Connect

    1995-09-01

    The goals of ISCCP and FIRE are, broadly speaking, to provide methods for the retrieval of cloud properties from satellites, and to improve cloud radiation models and the parameterization of clouds in GCMs. This study suggests a direction for GCM cloud parameterizations based on analysis of Landsat and ISCCP satellite data. For low level single layer clouds it is found that the mean retrieved liquid water pathe in cloudy pixels is essentially invariant to the cloud fraction, at least in the range 0.2 - 0.8. This result is very important since it allows the cloud fraction to be estimated if the mean liquid water path of cloud in a general circulation model gridcell is known. 3 figs.

  19. Difference in Fractional Occurrences of Precipitation Categories in Terms of Cloud Properties

    NASA Technical Reports Server (NTRS)

    Kawamoto, Kazuaki; Suzuki, Kentaroh

    2012-01-01

    The relationship between the precipitation stage and water cloud properties was studied in the mid-latitudes using space-borne radar and radiometer data, with a focus on a comparison between continental (over China) and oceanic (over the northwest Pacific) clouds. More specifically, fractional occurrences of the precipitation categories were investigated in terms of two-dimensional representations of cloud parameters, such as combinations of optical depth - effective particle radius, and liquid water path - droplet number density. As a result, systematic changes in the transition regarding pairs of the cloud parameters were well captured for all precipitation categories. The transition pattern was similar for both land and oceanic clouds. Notably, the ranges of all values of cloud parameters (except cloud droplet number density) were considerably larger for oceanic clouds for the precipitating category.

  20. Microphysical properties of low-level clouds and fogs in a mountain area of South Korea

    NASA Astrophysics Data System (ADS)

    Jeong, Jin-Yim; Lee, Chulkyu; Jung, Hyun-Sook; Nam, Jae-Chul

    2013-05-01

    Measurements of microphysical properties in low-level clouds and fogs were carried out at Daegwallyeong in the northeastern mountainous region of South Korea. The microphysical characteristics are presented through analyzing the number concentration, mean diameter, liquid water contents and size distribution of cloud particles sampled with the groundbased Forward Scattering Spectrometer Probe (FSSP). The aim of this study is to analyze the influence of the proposed cloud condensation nuclei (CCN) type on the size and the number of cloud droplets. Observational cases are classified 5 sectors according to backward air mass trajectories from the NOAA/ARL HYSPLIT model. Clean maritime cloud is characterized by sector 1 trajectories and clean continental cloud is by sector 2. Contaminated maritime cloud is by sector 3 and contaminated continental cloud is by sector 4. Sector 5 trajectories are undefined air masses. On average, the droplet number concentrations in marine clouds were lower than for continental clouds, while the mean diameters and liquid water contents for marine clouds were larger than for continental clouds. Our observed values of microphysical properties are similar to the reported values from previous studies.

  1. The Properties of Single Interstellar Clouds: Modified Cycle 1 Observations

    NASA Astrophysics Data System (ADS)

    Hobbs, Lewis

    1990-12-01

    WE PROPOSE TO USE THE ECHELLE AND 160M GRATINGS OF THE HIGH RESOLUTION SPECTROGRAPH OVER A TWO-YEAR PERIOD TO OBSERVE THE PROFILES OF INTERSTELLAR ABSORPTION LINES. THE COLUMN DENSITES OF 18 NEUTRAL OR IONIZED FORMS OF THE ELEMENTS C,N,O,Mg,Si,P,S,Fe, AND Zn WILL BE MEASURED IN THE APPROXIMATELY 100 INDIVIDUAL INTERSTELLAR CLOUDS ALONG THE LIGHT PATHS TO 18 BRIGHT, BROAD-LINED STARS OF EARLY SPECTRAL TYPE WITHIN 1 KPC OF THE SUN. THE PRIMARY PURPOSE OF THE OBSERVATIONS IS TO DETERMINE MORE ACCURATELY THAN WAS HITHERTO POSSIBLE THE FUNDAMENTAL PHYSICAL PROPERTIES OF THE RESOLVED CLOUDS, INCLUDING LINEAR SIZE, TEMPERATURE, TOTAL DENSITY, FRACTIONAL IONIZATION AND THE RELATIVE ABUNDANCES OF THE 9 SELECTED ELEMENTS. THE REST OF THIS OBSERVING PROGRAM IS CONTAINED IN APPROVED PROPOSAL ID = 3993; THE PROGRAM ENUMERATED HERE CONSISTS OF THAT PART OF OUR ORIGINAL PROGRAM, ID = 2251, WHICH REQUIRED MODIFICATION IN ORDER TO BE CARRIED OUT USING ONLY SIDE 2 OF THE GHRS. THIS PROGRAM THEREFORE CONSISTS OF ECH-B AND G160M OBSERVATIONS OF EACH OF 8 STARS AT 14 OR MORE WAVELENGTHS. PROGRAMS 2251 AND 3993 SHOULD BE CONSULTED FOR ADDITIONAL DETAILS.

  2. Leaf optical properties in Venezuelan cloud forest trees.

    PubMed

    Poorter, Lourens; Kwant, R.; Hernández, R.; Medina, E.; Werger, M. J. A.

    2000-04-01

    Leaf optical properties and related leaf characteristics were compared for thirteen cloud forest tree species differing in successional status. Sun leaves were sampled for the eight pioneer species and sun and shade leaves were sampled for the five climax species. Sun leaves had a slightly higher absorptance than shade leaves, although differences were small. Sun leaves had a higher leaf mass per unit area (LMA) and a lower chlorophyll concentration per unit leaf mass, resulting in similar chlorophyll concentrations per unit leaf area and hence similar light harvesting capacities as shade leaves. However, shade leaves realized a higher efficiency of absorptance per unit leaf biomass than sun leaves. There were few differences in leaf characteristics of sun leaves between the climax and pioneer species. Absorptance values of cloud forest species were comparable with values reported for rain forest and more seasonal forest species. Intraspecific variation in leaf absorptance was largely the result of variation in LMA, whereas interspecific variation in leaf absorptance was largely a result of variation in chlorophyll concentration per unit leaf area.

  3. The Properties of Single Interstellar Clouds Cycle 2

    NASA Astrophysics Data System (ADS)

    Hobbs, Lewis

    1991-07-01

    IN THIS CONTINUATION PROPOSAL, WE PROPOSE TO USE THE ECHELLEAND 160M GRATINGS OF THE HIGH RESOLUTION SPECTROGRAPH TO OBSERVE THE PZROFILES OF INTERSTELLAR ABSORPTION LINES, DURING THE SECOND YEAR OF A TWO-YEAR PROGRAM. IN THE TWO CYCLES TOGETHER, THE COLUMN DENSITES OF 17 NEUTRAL OR IONIZED FORMS OF THE ELEMENTS C,N,O,Mg,Si,P,S,Fe, AND Zn WILL BE MEASURED IN THE APPROXIMATELY 100 INDIVIDUAL INTERSTELLAR CLOUDS ALONG THE LIGHT PATHS TO 12 BRIGHT, BROAD-LINED STARS OF EARLY SPECTRAL TYPE WITHIN 1 KPC OF THE SUN. THE PRIMARY PURPOSE OF THE OBSERVATIONS IS TO DETERMINE MORE ACCURATELY THAN WAS HITHERTO POSSIBLE THE FUNDAMENTAL PHYSICAL PROPERTIES OF THE RESOLVED CLOUDS, INCLUDING LINEAR SIZE, TEMPERATURE, TOTAL DENSITY, FRACTIONAL IONIZATION AND THE RELATIVE ABUNDANCES OF THE 9 SELECTED ELEMENTS. THIS SECOND-YEAR PROGRAM CONSISTS OF ECH-B AND G160M OBSERVATIONS OF EACH OF 4 STARS AT 21 OR MORE WAVELENGTHS, AND OF A SUBSET OF THESE OBSERVATIONS FOR A FIFTH STAR, PI SCO. PROGRAMS 2251 AND 3993 SHOULD BE CONSULTED FOR DETAILS OF THE PREVIOUS OBSERVATIONS OBTAINED DURING CYCLE 1.

  4. A Multi-Year Data Set of Cloud Properties Derived for CERES from Aqua, Terra, and TRMM

    NASA Technical Reports Server (NTRS)

    Minnis, Patrick; Sunny Sun-Mack; Trepte, Quinz Z.; Yan Chen; Brown, Richard R.; Gibson, Sharon C.; Heck, Michael L.; Dong, Xiquan; Xi, Baike

    2007-01-01

    The Clouds and Earth's Radiant Energy System (CERES) Project is producing a suite of cloud properties from high-resolution imagers on several satellites and matching them precisely with broadband radiance data to study the influence of clouds and radiation on climate. The cloud properties generally compare well with independent validation sources. Distinct differences are found between the CERES cloud properties and those derived with other algorithms from the same imager data. CERES products will be updated beginning in late 2006.

  5. Climatological and radiative properties of midlatitude cirrus clouds derived by automatic evaluation of lidar measurements

    NASA Astrophysics Data System (ADS)

    Kienast-Sjögren, Erika; Rolf, Christian; Seifert, Patric; Krieger, Ulrich K.; Luo, Bei P.; Krämer, Martina; Peter, Thomas

    2016-06-01

    Cirrus, i.e., high, thin clouds that are fully glaciated, play an important role in the Earth's radiation budget as they interact with both long- and shortwave radiation and affect the water vapor budget of the upper troposphere and stratosphere. Here, we present a climatology of midlatitude cirrus clouds measured with the same type of ground-based lidar at three midlatitude research stations: at the Swiss high alpine Jungfraujoch station (3580 m a.s.l.), in Zürich (Switzerland, 510 m a.s.l.), and in Jülich (Germany, 100 m a.s.l.). The analysis is based on 13 000 h of measurements from 2010 to 2014. To automatically evaluate this extensive data set, we have developed the Fast LIdar Cirrus Algorithm (FLICA), which combines a pixel-based cloud-detection scheme with the classic lidar evaluation techniques. We find mean cirrus optical depths of 0.12 on Jungfraujoch and of 0.14 and 0.17 in Zürich and Jülich, respectively. Above Jungfraujoch, subvisible cirrus clouds (τ < 0.03) have been observed during 6 % of the observation time, whereas above Zürich and Jülich fewer clouds of that type were observed. Cirrus have been observed up to altitudes of 14.4 km a.s.l. above Jungfraujoch, whereas they have only been observed to about 1 km lower at the other stations. These features highlight the advantage of the high-altitude station Jungfraujoch, which is often in the free troposphere above the polluted boundary layer, thus enabling lidar measurements of thinner and higher clouds. In addition, the measurements suggest a change in cloud morphology at Jungfraujoch above ˜ 13 km, possibly because high particle number densities form in the observed cirrus clouds, when many ice crystals nucleate in the high supersaturations following rapid uplifts in lee waves above mountainous terrain. The retrieved optical properties are used as input for a radiative transfer model to estimate the net cloud radiative forcing, CRFNET, for the analyzed cirrus clouds. All cirrus detected

  6. Properties of CIRRUS Overlapping Clouds as Deduced from the GOES-12 Imagery Data

    NASA Technical Reports Server (NTRS)

    Chang, Fu-Lung; Minnis, Patrick; Lin, Bing; Sun-Mack, Sunny; Khaiyer, Mandana

    2006-01-01

    Understanding the impact of cirrus clouds on modifying both the solar reflected and terrestrial emitted radiations is crucial for climate studies. Unlike most boundary layer stratus and stratocumulus clouds that have a net cooling effect on the climate, high-level thin cirrus clouds can have a warming effect on our climate. Many research efforts have been devoted to retrieving cirrus cloud properties due to their ubiquitous presence. However, using satellite observations to detect and/or retrieve cirrus cloud properties faces two major challenges. First, they are often semitransparent at visible to infrared wavelengths; and secondly, they often occur over a lower cloud system. The overlapping of high-level cirrus and low-level stratus cloud poses a difficulty in determining the individual cloud top altitudes and optical properties, especially when the signals from cirrus clouds are overwhelmed by the signals of stratus clouds. Moreover, the operational satellite retrieval algorithms, which often assume only single layer cloud in the development of cloud retrieval techniques, cannot resolve the cloud overlapping situation properly. The new geostationary satellites, starting with the Twelfth Geostationary Operational Environmental Satellite (GOES-12), are providing a new suite of imager bands that have replaced the conventional 12-micron channel with a 13.3-micron CO2 absorption channel. The replacement of the 13.3-micron channel allows for the application of a CO2-slicing retrieval technique (Chahine et al. 1974; Smith and Platt 1978), which is one of the important passive satellite methods for remote sensing the altitudes of mid to high-level clouds. Using the CO2- slicing technique is more effective in detecting semitransparent cirrus clouds than using the conventional infrared-window method.

  7. Evaluation of Cloud Physical Properties of ECMWF Analysis and Re-Analysis (ERA-40 and ERA Interim) against CERES Tropical Deep Convective Cloud Object Observations

    NASA Technical Reports Server (NTRS)

    Xu, Kuan-Man

    2008-01-01

    This study presents an approach that converts the vertical profiles of grid-averaged cloud properties from large-scale models to probability density functions (pdfs) of subgrid-cell cloud physical properties measured at satellite footprints. Cloud physical and radiative properties, rather than just cloud and precipitation occurrences, of assimilated cloud systems by the European Center for Medium-range Weather Forecasts (ECMWF) operational analysis (EOA) and ECMWF Re-Analyses (ERA-40 and ERA Interim) are validated against those obtained from Earth Observing System satellite cloud object data for January-August 1998 and March 2000 periods. These properties include ice water path (IWP), cloud-top height and temperature, cloud optical depth and solar and infrared radiative fluxes. Each cloud object, a contiguous region with similar cloud physical properties, is temporally and spatially matched with EOA and ERA-40 data. Results indicate that most pdfs of EOA and ERA-40 cloud physical and radiative properties agree with those of satellite observations of the tropical deep convective cloud-object type for the January-August 1998 period. There are, however, significant discrepancies in selected ranges of the cloud property pdfs such as the upper range of EOA cloud top height. A major discrepancy is that the dependence of the pdfs on the cloud object size for both EOA and ERA-40 is not as strong as in the observations. Modifications to the cloud parameterization in ECMWF that occurred in October 1999 eliminate the clouds near the tropopause but shift power of the pdf to lower cloud-top heights and greatly reduce the ranges of IWP and cloud optical depth pdfs. These features persist in ERA-40 due to the use of the same cloud parameterizations. The downgrade of data assimilation technique and the lack of snow water content information in ERA-40, not the coarser horizontal grid resolution, are also responsible for the disagreements with observed pdfs of cloud physical

  8. Global Weather States and Their Properties from Passive and Active Satellite Cloud Retrievals

    NASA Technical Reports Server (NTRS)

    Tselioudis, George; Rossow, William; Zhang, Yuanchong; Konsta, Dimitra

    2013-01-01

    In this study, the authors apply a clustering algorithm to International Satellite Cloud Climatology Project (ISCCP) cloud optical thickness-cloud top pressure histograms in order to derive weather states (WSs) for the global domain. The cloud property distribution within each WS is examined and the geographical variability of each WS is mapped. Once the global WSs are derived, a combination of CloudSat and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) vertical cloud structure retrievals is used to derive the vertical distribution of the cloud field within each WS. Finally, the dynamic environment and the radiative signature of the WSs are derived and their variability is examined. The cluster analysis produces a comprehensive description of global atmospheric conditions through the derivation of 11 WSs, each representing a distinct cloud structure characterized by the horizontal distribution of cloud optical depth and cloud top pressure. Matching those distinct WSs with cloud vertical profiles derived from CloudSat and CALIPSO retrievals shows that the ISCCP WSs exhibit unique distributions of vertical layering that correspond well to the horizontal structure of cloud properties. Matching the derived WSs with vertical velocity measurements shows a normal progression in dynamic regime when moving from the most convective to the least convective WS. Time trend analysis of the WSs shows a sharp increase of the fair-weather WS in the 1990s and a flattening of that increase in the 2000s. The fact that the fair-weather WS is the one with the lowest cloud radiative cooling capability implies that this behavior has contributed excess radiative warming to the global radiative budget during the 1990s.

  9. Frequency and causes of failed MODIS cloud property retrievals for liquid phase clouds over global oceans.

    PubMed

    Cho, Hyoun-Myoung; Zhang, Zhibo; Meyer, Kerry; Lebsock, Matthew; Platnick, Steven; Ackerman, Andrew S; Di Girolamo, Larry; C-Labonnote, Laurent; Cornet, Céline; Riedi, Jerome; Holz, Robert E

    2015-05-16

    Moderate Resolution Imaging Spectroradiometer (MODIS) retrieves cloud droplet effective radius (re ) and optical thickness (τ) by projecting observed cloud reflectances onto a precomputed look-up table (LUT). When observations fall outside of the LUT, the retrieval is considered "failed" because no combination of τ and re within the LUT can explain the observed cloud reflectances. In this study, the frequency and potential causes of failed MODIS retrievals for marine liquid phase (MLP) clouds are analyzed based on 1 year of Aqua MODIS Collection 6 products and collocated CALIOP and CloudSat observations. The retrieval based on the 0.86 µm and 2.1 µm MODIS channel combination has an overall failure rate of about 16% (10% for the 0.86 µm and 3.7 µm combination). The failure rates are lower over stratocumulus regimes and higher over the broken trade wind cumulus regimes. The leading type of failure is the "re too large" failure accounting for 60%-85% of all failed retrievals. The rest is mostly due to the "re too small" or τ retrieval failures. Enhanced retrieval failure rates are found when MLP cloud pixels are partially cloudy or have high subpixel inhomogeneity, are located at special Sun-satellite viewing geometries such as sunglint, large viewing or solar zenith angles, or cloudbow and glory angles, or are subject to cloud masking, cloud overlapping, and/or cloud phase retrieval issues. The majority (more than 84%) of failed retrievals along the CALIPSO track can be attributed to at least one or more of these potential reasons. The collocated CloudSat radar reflectivity observations reveal that the remaining failed retrievals are often precipitating. It remains an open question whether the extremely large re values observed in these clouds are the consequence of true cloud microphysics or still due to artifacts not included in this study.

  10. Remote Sensing of Cloud Properties using Ground-based Measurements of Zenith Radiance

    NASA Technical Reports Server (NTRS)

    Chiu, J. Christine; Marshak, Alexander; Knyazikhin, Yuri; Wiscombe, Warren J.; Barker, Howard W.; Barnard, James C.; Luo, Yi

    2006-01-01

    An extensive verification of cloud property retrievals has been conducted for two algorithms using zenith radiances measured by the Atmospheric Radiation Measurement (ARM) Program ground-based passive two-channel (673 and 870 nm) Narrow Field-Of-View Radiometer. The underlying principle of these algorithms is that clouds have nearly identical optical properties at these wavelengths, but corresponding spectral surface reflectances (for vegetated surfaces) differ significantly. The first algorithm, the RED vs. NIR, works for a fully three-dimensional cloud situation. It retrieves not only cloud optical depth, but also an effective radiative cloud fraction. Importantly, due to one-second time resolution of radiance measurements, we are able, for the first time, to capture detailed changes in cloud structure at the natural time scale of cloud evolution. The cloud optical depths tau retrieved by this algorithm are comparable to those inferred from both downward fluxes in overcast situations and microwave brightness temperatures for broken clouds. Moreover, it can retrieve tau for thin patchy clouds, where flux and microwave observations fail to detect them. The second algorithm, referred to as COUPLED, couples zenith radiances with simultaneous fluxes to infer 2. In general, the COUPLED and RED vs. NIR algorithms retrieve consistent values of tau. However, the COUPLED algorithm is more sensitive to the accuracies of measured radiance, flux, and surface reflectance than the RED vs. NIR algorithm. This is especially true for thick overcast clouds where it may substantially overestimate z.

  11. Contrasting influences of aerosols on cloud properties during deficient and abundant monsoon years.

    PubMed

    Patil, Nitin; Dave, Prashant; Venkataraman, Chandra

    2017-03-24

    Direct aerosol radiative forcing facilitates the onset of Indian monsoon rainfall, based on synoptic scale fast responses acting over timescales of days to a month. Here, we examine relationships between aerosols and coincident clouds over the Indian subcontinent, using observational data from 2000 to 2009, from the core monsoon region. Season mean and daily timescales were considered. The correlation analyses of cloud properties with aerosol optical depth revealed that deficient monsoon years were characterized by more frequent and larger decreases in cloud drop size and ice water path, but increases in cloud top pressure, with increases in aerosol abundance. The opposite was observed during abundant monsoon years. The correlations of greater aerosol abundance, with smaller cloud drop size, lower evidence of ice processes and shallower cloud height, during deficient rainfall years, imply cloud inhibition; while those with larger cloud drop size, greater ice processes and a greater cloud vertical extent, during abundant rainfall years, suggest cloud invigoration. The study establishes that continental aerosols over India alter cloud properties in diametrically opposite ways during contrasting monsoon years. The mechanisms underlying these effects need further analysis.

  12. Contrasting influences of aerosols on cloud properties during deficient and abundant monsoon years

    NASA Astrophysics Data System (ADS)

    Patil, Nitin; Dave, Prashant; Venkataraman, Chandra

    2017-03-01

    Direct aerosol radiative forcing facilitates the onset of Indian monsoon rainfall, based on synoptic scale fast responses acting over timescales of days to a month. Here, we examine relationships between aerosols and coincident clouds over the Indian subcontinent, using observational data from 2000 to 2009, from the core monsoon region. Season mean and daily timescales were considered. The correlation analyses of cloud properties with aerosol optical depth revealed that deficient monsoon years were characterized by more frequent and larger decreases in cloud drop size and ice water path, but increases in cloud top pressure, with increases in aerosol abundance. The opposite was observed during abundant monsoon years. The correlations of greater aerosol abundance, with smaller cloud drop size, lower evidence of ice processes and shallower cloud height, during deficient rainfall years, imply cloud inhibition; while those with larger cloud drop size, greater ice processes and a greater cloud vertical extent, during abundant rainfall years, suggest cloud invigoration. The study establishes that continental aerosols over India alter cloud properties in diametrically opposite ways during contrasting monsoon years. The mechanisms underlying these effects need further analysis.

  13. Contrasting influences of aerosols on cloud properties during deficient and abundant monsoon years

    PubMed Central

    Patil, Nitin; Dave, Prashant; Venkataraman, Chandra

    2017-01-01

    Direct aerosol radiative forcing facilitates the onset of Indian monsoon rainfall, based on synoptic scale fast responses acting over timescales of days to a month. Here, we examine relationships between aerosols and coincident clouds over the Indian subcontinent, using observational data from 2000 to 2009, from the core monsoon region. Season mean and daily timescales were considered. The correlation analyses of cloud properties with aerosol optical depth revealed that deficient monsoon years were characterized by more frequent and larger decreases in cloud drop size and ice water path, but increases in cloud top pressure, with increases in aerosol abundance. The opposite was observed during abundant monsoon years. The correlations of greater aerosol abundance, with smaller cloud drop size, lower evidence of ice processes and shallower cloud height, during deficient rainfall years, imply cloud inhibition; while those with larger cloud drop size, greater ice processes and a greater cloud vertical extent, during abundant rainfall years, suggest cloud invigoration. The study establishes that continental aerosols over India alter cloud properties in diametrically opposite ways during contrasting monsoon years. The mechanisms underlying these effects need further analysis. PMID:28337991

  14. Factors Controlling the Properties of Multi-Phase Arctic Stratocumulus Clouds

    NASA Technical Reports Server (NTRS)

    Fridlind, Ann; Ackerman, Andrew; Menon, Surabi

    2005-01-01

    The 2004 Multi-Phase Arctic Cloud Experiment (M-PACE) IOP at the ARM NSA site focused on measuring the properties of autumn transition-season arctic stratus and the environmental conditions controlling them, including concentrations of heterogeneous ice nuclei. Our work aims to use a large-eddy simulation (LES) code with embedded size-resolved aerosol and cloud microphysics to identify factors controlling multi-phase arctic stratus. Our preliminary simulations of autumn transition-season clouds observed during the 1994 Beaufort and Arctic Seas Experiment (BASE) indicated that low concentrations of ice nuclei, which were not measured, may have significantly lowered liquid water content and thereby stabilized cloud evolution. However, cloud drop concentrations appeared to be virtually immune to changes in liquid water content, indicating an active Bergeron process with little effect of collection on drop number concentration. We will compare these results with preliminary simulations from October 8-13 during MPACE. The sensitivity of cloud properties to uncertainty in other factors, such as large-scale forcings and aerosol profiles, will also be investigated. Based on the LES simulations with M-PACE data, preliminary results from the NASA GlSS single-column model (SCM) will be used to examine the sensitivity of predicted cloud properties to changing cloud drop number concentrations for multi-phase arctic clouds. Present parametrizations assumed fixed cloud droplet number concentrations and these will be modified using M-PACE data.

  15. The properties of optical lightning flashes and the clouds they illuminate

    NASA Astrophysics Data System (ADS)

    Peterson, Michael; Deierling, Wiebke; Liu, Chuntao; Mach, Douglas; Kalb, Christina

    2017-01-01

    Optical lightning sensors like the Optical Transient Detector and Lightning Imaging Sensor (LIS) measure total lightning across large swaths of the globe with high detection efficiency. With two upcoming missions that employ these sensors - LIS on the International Space Station and the Geostationary Lightning Mapper on the GOES-R satellite - there has been increased interest in what these measurements can reveal about lightning and thunderstorms in addition to total flash activity. Optical lightning imagers are capable of observing the characteristics of individual flashes that include their sizes, durations, and radiative energies. However, it is important to exercise caution when interpreting trends in optical flash measurements because they can be affected by the scene. This study uses coincident measurements from the Tropical Rainfall Measuring Mission (TRMM) satellite to examine the properties of LIS flashes and the surrounding cloud regions they illuminate. These combined measurements are used to assess to what extent optical flash characteristics can be used to make inferences about flash structure and energetics. Clouds illuminated by lightning over land and ocean regions that are otherwise similar based on TRMM measurements are identified. Even when LIS flashes occur in similar clouds and background radiances, oceanic flashes are still shown to be larger, brighter, longer lasting, more prone to horizontal propagation, and to contain more groups than their land-based counterparts. This suggests that the optical trends noted in literature are not entirely the result of radiative transfer effects but rather stem from physical differences in the flashes.

  16. Development of an Algorithm for MODIS and VIIRS Cloud Optical Property Data Record Continuity

    NASA Astrophysics Data System (ADS)

    Meyer, K.; Platnick, S. E.; Ackerman, S. A.; Heidinger, A. K.; Holz, R.; Wind, G.; Amarasinghe, N.; Marchant, B.

    2015-12-01

    The launch of Suomi NPP in the fall of 2011 began the next generation of U.S. operational polar orbiting environmental observations. Similar to MODIS, the VIIRS imager provides visible through IR observations at moderate spatial resolution with a 1330 LT equatorial crossing consistent with MODIS on the Aqua platform. However, unlike MODIS, VIIRS lacks key water vapor and CO2 absorbing channels used by the MODIS cloud algorithms for high cloud detection and cloud-top property retrievals. In addition, there is a significant change in the spectral location of the 2.1μm shortwave-infrared channel used by MODIS for cloud optical/microphysical retrievals. Given the instrument differences between MODIS EOS and VIIRS S-NPP/JPSS, we discuss our adopted method for merging the 15+ year MODIS observational record with VIIRS in order to generate cloud optical property data record continuity across the observing systems. The optical property retrieval code uses heritage algorithms that produce the existing MODIS cloud optical and microphysical properties product (MOD06). As explained in other presentations submitted to this session, the NOAA AWG/CLAVR-x cloud-top property algorithm and a common MODIS-VIIRS cloud mask feed into the optical property algorithm to account for the different channel sets of the two imagers. Data granule and aggregated examples for the current version of the algorithm will be shown.

  17. Laboratory study of microphysical and scattering properties of corona-producing cirrus clouds.

    PubMed

    Järvinen, E; Vochezer, P; Möhler, O; Schnaiter, M

    2014-11-01

    Corona-producing cirrus clouds were generated and measured under chamber conditions at the AIDA cloud chamber in Karlsruhe. We were able to measure the scattering properties as well as microphysical properties of these clouds under well-defined laboratory conditions in contrast with previous studies of corona-producing clouds, where the measurements were conducted by means of lidar and in situ aircraft measurements. Our results are in agreement with those of previous studies, confirming that corona-producing cirrus clouds consist of a narrow distribution of small (median Dp=19-32  μm) and compact ice crystals. We showed that the ice crystals in these clouds are most likely formed in homogeneous freezing processes. As a result of the homogeneous freezing process, the ice crystals grow uniformly in size; furthermore, the majority of the ice crystals have rough surface features.

  18. Continuous Profiles of Cloud Microphysical Properties for the Fixed Atmospheric Radiation Measurement Sites

    SciTech Connect

    Jensen, M; Jensen, K

    2006-06-01

    The Atmospheric Radiation Measurement (ARM) Program defined a specific metric for the third quarter of Fiscal Year 2006 to produce and refine a one-year continuous time series of cloud microphysical properties based on cloud radar measurements for each of the fixed ARM sites. To accomplish this metric, we used a combination of recently developed algorithms that interpret radar reflectivity profiles, lidar backscatter profiles, and microwave brightness temperatures into the context of the underlying cloud microphysical structure.

  19. Black carbon mixing state impacts on cloud microphysical properties: effects of aerosol plume and environmental conditions

    SciTech Connect

    Ching, Ping Pui; Riemer, Nicole; West, Matthew

    2016-05-27

    Black carbon (BC) is usually mixed with other aerosol species within individual aerosol particles. This mixture, along with the particles' size and morphology, determines the particles' optical and cloud condensation nuclei properties, and hence black carbon's climate impacts. In this study the particle-resolved aerosol model PartMC-MOSAIC was used to quantify the importance of black carbon mixing state for predicting cloud microphysical quantities. Based on a set of about 100 cloud parcel simulations a process level analysis framework was developed to attribute the response in cloud microphysical properties to changes in the underlying aerosol population ("plume effect") and the cloud parcel cooling rate ("parcel effect"). It shows that the response of cloud droplet number concentration to changes in BC emissions depends on the BC mixing state. When the aerosol population contains mainly aged BC particles an increase in BC emission results in increasing cloud droplet number concentrations ("additive effect"). In contrast, when the aerosol population contains mainly fresh BC particles they act as sinks for condensable gaseous species, resulting in a decrease in cloud droplet number concentration as BC emissions are increased ("competition effect"). Additionally, we quantified the error in cloud microphysical quantities when neglecting the information on BC mixing state, which is often done in aerosol models. The errors ranged from -12% to +45% for the cloud droplet number fraction, from 0% to +1022% for the nucleation-scavenged black carbon (BC) mass fraction, from -12% to +4% for the effective radius, and from -30% to +60% for the relative dispersion.

  20. Arctic Mixed-Phase Cloud Properties from AERI Lidar Observations: Algorithm and Results from SHEBA

    SciTech Connect

    Turner, David D.

    2005-04-01

    A new approach to retrieve microphysical properties from mixed-phase Arctic clouds is presented. This mixed-phase cloud property retrieval algorithm (MIXCRA) retrieves cloud optical depth, ice fraction, and the effective radius of the water and ice particles from ground-based, high-resolution infrared radiance and lidar cloud boundary observations. The theoretical basis for this technique is that the absorption coefficient of ice is greater than that of liquid water from 10 to 13 μm, whereas liquid water is more absorbing than ice from 16 to 25 μm. MIXCRA retrievals are only valid for optically thin (τvisible < 6) single-layer clouds when the precipitable water vapor is less than 1 cm. MIXCRA was applied to the Atmospheric Emitted Radiance Interferometer (AERI) data that were collected during the Surface Heat Budget of the Arctic Ocean (SHEBA) experiment from November 1997 to May 1998, where 63% of all of the cloudy scenes above the SHEBA site met this specification. The retrieval determined that approximately 48% of these clouds were mixed phase and that a significant number of clouds (during all 7 months) contained liquid water, even for cloud temperatures as low as 240 K. The retrieved distributions of effective radii for water and ice particles in single-phase clouds are shown to be different than the effective radii in mixed-phase clouds.

  1. Investigation of cloud properties and atmospheric stability with MODIS

    NASA Technical Reports Server (NTRS)

    Menzel, Paul

    1993-01-01

    The work accomplished with the MAS (MODIS Airborne Simulator) during the TOGA-COARE (Tropical Ocean Global Atmosphere - Coupled Ocean Atmosphere Response Experiment) from January through June 1993 included cloud investigations with longwave CO2 channels (out to 13.9 microns) that reconfigured spectral channels. The comparison data was used with HIRS (high resolution Infrared Radiation Sounder) data from FIRE (First ISSCP Regional Experiment), CEPEX, and SCAR (Smoke Clouds, Aerosol and Radiation) data for the development of a two layer cloud CO2 slicing algorithm and the development of multi-spectral cloud detection algorithms (specifically tri-spectral) for cloud identification. Regarding the latter, a clustering analysis was added to improve cloud identification within the scatter diagram of tri-spectral (8, 11, and 12 microns) brightness temperatures. Via the regressions of the 8 - 11 and the 11 - 12 micron brightness temperature differences versus precipitable water, the problem of clear sky identification in the scatter diagram was further addressed. Comparison of the tri-spectral technique and visible channel reflectance ratioing indicate the tri-spectral infrared method distinguishes cloud phase more consistently in mixed cloud scenes rather than single phase cloud scenes where visible ratioing performs best.

  2. Impacts of the Manaus pollution plume on the microphysical properties of Amazonian warm-phase clouds in the wet season

    SciTech Connect

    Cecchini, Micael A.; Machado, Luiz A. T.; Comstock, Jennifer M.; Mei, Fan; Wang, Jian; Fan, Jiwen; Tomlinson, Jason M.; Schmid, Beat; Albrecht, Rachel; Martin, Scot T.; Artaxo, Paulo

    2016-01-01

    The remote atmosphere over the Amazon can be similar to oceanic regions in terms of aerosol conditions and cloud type formations. This is especially true during the wet season. The main aerosol-related disturbances over the Amazon have both natural sources, such as dust transport from Africa, and anthropogenic sources, such as biomass burning or urban pollution. The present work considers the impacts of the latter on the microphysical properties of warm-phase clouds by analysing observations of the interactions between the Manaus pollution plume and its surroundings, as part of the GoAmazon2014/5 Experiment. The analysed period corresponds to the wet season (specifically from February to March 2014 and corresponding to the first Intensive Operating Period (IOP1) of GoAmazon2014/5). The droplet size distributions reported are in the range 1 µm ≤ D≤50 µm in order to capture the processes leading up to the precipitation formation. The wet season largely presents a clean background atmosphere characterized by frequent rain showers. As such, the contrast between background clouds and those affected by the Manaus pollution can be observed and detailed. The focus is on the characteristics of the initial microphysical properties in cumulus clouds predominantly at their early stages. The pollution-affected clouds are found to have smaller effective diameters and higher droplet number concentrations. The differences range from 10 to 40% for the effective diameter and are as high as 1000% for droplet concentration for the same vertical levels. The growth rates of droplets with altitude are slower for pollution-affected clouds (2.90 compared to 5.59 µm km₋1), as explained by the absence of bigger droplets at the onset of cloud development. Clouds under background conditions have higher concentrations of larger droplets (>20 µm) near the cloud base, which would contribute significantly to the growth rates through the collision

  3. Impacts of the Manaus pollution plume on the microphysical properties of Amazonian warm-phase clouds in the wet season

    SciTech Connect

    Cecchini, Micael A.; Machado, Luiz A. T.; Comstock, Jennifer M.; Mei, Fan; Wang, Jian; Fan, Jiwen; Tomlinson, Jason M.; Schmid, Beat; Albrecht, Rachel; Martin, Scot T.; Artaxo, Paulo

    2016-06-09

    The remote atmosphere over the Amazon can be similar to oceanic regions in terms of aerosol conditions and cloud type formations. This is especially true during the wet season. The main aerosol-related disturbances over the Amazon have both natural sources, such as dust transport from Africa, and anthropogenic sources, such as biomass burning or urban pollution. The present work considers the impacts of the latter on the microphysical properties of warm-phase clouds by analyzing observations of the interactions between the Manaus pollution plume and its surroundings, as part of the GoAmazon2014/5 Experiment. The analyzed period corresponds to the wet season (specifically from February to March 2014 and corresponding to the first Intensive Operating Period (IOP1) of GoAmazon2014/5). The droplet size distributions reported are in the range 1 µm ≤ D ≤ 50 µm in order to capture the processes leading up to the precipitation formation. The wet season largely presents a clean background atmosphere characterized by frequent rain showers. As such, the contrast between background clouds and those affected by the Manaus pollution can be observed and detailed. The focus is on the characteristics of the initial microphysical properties in cumulus clouds predominantly at their early stages. The pollution-affected clouds are found to have smaller effective diameters and higher droplet number concentrations. The differences range from 10 to 40 % for the effective diameter and are as high as 1000% for droplet concentration for the same vertical levels. The growth rates of droplets with altitude are slower for pollution-affected clouds (2.90 compared to 5.59 µm km–1), as explained by the absence of bigger droplets at the onset of cloud development. Clouds under background conditions have higher concentrations of larger droplets (> 20 µm) near the cloud base, which would contribute significantly to the growth rates through the collision

  4. Impacts of the Manaus pollution plume on the microphysical properties of Amazonian warm-phase clouds in the wet season

    DOE PAGES

    Cecchini, Micael A.; Machado, Luiz A. T.; Comstock, Jennifer M.; ...

    2016-06-09

    The remote atmosphere over the Amazon can be similar to oceanic regions in terms of aerosol conditions and cloud type formations. This is especially true during the wet season. The main aerosol-related disturbances over the Amazon have both natural sources, such as dust transport from Africa, and anthropogenic sources, such as biomass burning or urban pollution. The present work considers the impacts of the latter on the microphysical properties of warm-phase clouds by analyzing observations of the interactions between the Manaus pollution plume and its surroundings, as part of the GoAmazon2014/5 Experiment. The analyzed period corresponds to the wet seasonmore » (specifically from February to March 2014 and corresponding to the first Intensive Operating Period (IOP1) of GoAmazon2014/5). The droplet size distributions reported are in the range 1 µm ≤ D ≤ 50 µm in order to capture the processes leading up to the precipitation formation. The wet season largely presents a clean background atmosphere characterized by frequent rain showers. As such, the contrast between background clouds and those affected by the Manaus pollution can be observed and detailed. The focus is on the characteristics of the initial microphysical properties in cumulus clouds predominantly at their early stages. The pollution-affected clouds are found to have smaller effective diameters and higher droplet number concentrations. The differences range from 10 to 40 % for the effective diameter and are as high as 1000% for droplet concentration for the same vertical levels. The growth rates of droplets with altitude are slower for pollution-affected clouds (2.90 compared to 5.59 µm km–1), as explained by the absence of bigger droplets at the onset of cloud development. Clouds under background conditions have higher concentrations of larger droplets (> 20 µm) near the cloud base, which would contribute significantly to the growth rates through the collision–coalescence process. The

  5. Impacts of the Manaus pollution plume on the microphysical properties of Amazonian warm-phase clouds in the wet season

    NASA Astrophysics Data System (ADS)

    Cecchini, Micael A.; Machado, Luiz A. T.; Comstock, Jennifer M.; Mei, Fan; Wang, Jian; Fan, Jiwen; Tomlinson, Jason M.; Schmid, Beat; Albrecht, Rachel; Martin, Scot T.; Artaxo, Paulo

    2016-06-01

    The remote atmosphere over the Amazon can be similar to oceanic regions in terms of aerosol conditions and cloud type formations. This is especially true during the wet season. The main aerosol-related disturbances over the Amazon have both natural sources, such as dust transport from Africa, and anthropogenic sources, such as biomass burning or urban pollution. The present work considers the impacts of the latter on the microphysical properties of warm-phase clouds by analysing observations of the interactions between the Manaus pollution plume and its surroundings, as part of the GoAmazon2014/5 Experiment. The analysed period corresponds to the wet season (specifically from February to March 2014 and corresponding to the first Intensive Operating Period (IOP1) of GoAmazon2014/5). The droplet size distributions reported are in the range 1 µm ≤ D ≤ 50 µm in order to capture the processes leading up to the precipitation formation. The wet season largely presents a clean background atmosphere characterized by frequent rain showers. As such, the contrast between background clouds and those affected by the Manaus pollution can be observed and detailed. The focus is on the characteristics of the initial microphysical properties in cumulus clouds predominantly at their early stages. The pollution-affected clouds are found to have smaller effective diameters and higher droplet number concentrations. The differences range from 10 to 40 % for the effective diameter and are as high as 1000 % for droplet concentration for the same vertical levels. The growth rates of droplets with altitude are slower for pollution-affected clouds (2.90 compared to 5.59 µm km-1), as explained by the absence of bigger droplets at the onset of cloud development. Clouds under background conditions have higher concentrations of larger droplets (> 20 µm) near the cloud base, which would contribute significantly to the growth rates through the collision-coalescence process. The overall shape

  6. Effects of spherical inclusions on scattering properties of small ice cloud particles

    NASA Astrophysics Data System (ADS)

    Hong, Gang; Minnis, Patrick

    2015-04-01

    The single-scattering properties of small ice crystals containing four types of spherical inclusions, ammonium sulfate (NH4)2SO4, ammonium nitrate NH3NO3, air bubbles, and soot, are investigated at 0.65 and 2.13 µm. Small, randomly oriented hexagonal ice columns with spherical inclusions that are randomly distributed with standard gamma size distributions in the columns are considered in the present study. Ice crystals with inclusions of (NH4)2SO4 and NH3NO3 essentially have the same features due to their similar refractive indices. Nonzero scattering matrix elements are sensitive to inclusion type and amount, and show differences between 0.65 and 2.13 µm. The extinction efficiency Qe of small ice crystals at 0.65 µm is near 2.0 and essentially unaffected by variations in inclusion volume, in contrast to strong influences of inclusion amount on Qe at 2.13 µm. The single-scattering albedo ϖ0 of ice crystals, nearly equal to 1.0, is not affected by inclusions of (NH4)2SO4, NH3NO3, and air bubbles. Soot inclusions strongly affect ϖ0, which decreases to about 0.5 with increasing soot amounts. The asymmetry factor g is substantially affected by (NH4)2SO4, NH3NO3, and soot and the variations in their amounts. Full Stokes parameters of cirrus clouds consisting of uniform hexagonal ice columns with inclusions are computed using a polarized radiative transfer model. Sensitivities of light intensity and polarization of cirrus clouds to types and amounts of inclusions and cirrus cloud optical thicknesses are found to depend on wavelength. The present results suggest that different types of inclusions for small ice crystals should be considered when developing realistic ice crystal optical properties, and that light intensity and polarization of cirrus clouds and their angular distribution features, in the absence of other effects such as cavities and surface roughness, imply the potential for identifying pure ice crystals from those with aerosol inclusions.

  7. Detection and Retrieval of Multi-Layered Cloud Properties Using Satellite Data

    NASA Technical Reports Server (NTRS)

    Minnis, Patrick; Sun-Mack, Sunny; Chen, Yan; Yi, Helen; Huang, Jian-Ping; Nguyen, Louis; Khaiyer, Mandana M.

    2005-01-01

    Four techniques for detecting multilayered clouds and retrieving the cloud properties using satellite data are explored to help address the need for better quantification of cloud vertical structure. A new technique was developed using multispectral imager data with secondary imager products (infrared brightness temperature differences, BTD). The other methods examined here use atmospheric sounding data (CO2-slicing, CO2), BTD, or microwave data. The CO2 and BTD methods are limited to optically thin cirrus over low clouds, while the MWR methods are limited to ocean areas only. This paper explores the use of the BTD and CO2 methods as applied to Moderate Resolution Imaging Spectroradiometer (MODIS) and Advanced Microwave Scanning Radiometer EOS (AMSR-E) data taken from the Aqua satellite over ocean surfaces. Cloud properties derived from MODIS data for the Clouds and the Earth's Radiant Energy System (CERES) Project are used to classify cloud phase and optical properties. The preliminary results focus on a MODIS image taken off the Uruguayan coast. The combined MW visible infrared (MVI) method is assumed to be the reference for detecting multilayered ice-over-water clouds. The BTD and CO2 techniques accurately match the MVI classifications in only 51 and 41% of the cases, respectively. Much additional study is need to determine the uncertainties in the MVI method and to analyze many more overlapped cloud scenes.

  8. An Estimate of Low-Cloud Feedbacks from Variations of Cloud Radiative and Physical Properties with Sea Surface Temperature on Interannual Time Scales

    NASA Technical Reports Server (NTRS)

    Eitzen, Zachary A.; Xu, Kuan-Man; Wong, Takmeng

    2011-01-01

    Simulations of climate change have yet to reach a consensus on the sign and magnitude of the changes in physical properties of marine boundary layer clouds. In this study, the authors analyze how cloud and radiative properties vary with SST anomaly in low-cloud regions, based on five years (March 2000 - February 2005) of Clouds and the Earth s Radiant Energy System (CERES) -- Terra monthly gridded data and matched European Centre for Medium-Range Weather Forecasts (ECMWF) meteorological reanalaysis data. In particular, this study focuses on the changes in cloud radiative effect, cloud fraction, and cloud optical depth with SST anomaly. The major findings are as follows. First, the low-cloud amount (-1.9% to -3.4% /K) and the logarithm of low-cloud optical depth (-0.085 to -0.100/K) tend to decrease while the net cloud radiative effect (3.86 W/m(exp 2)/ K) becomes less negative as SST anomalies increase. These results are broadly consistent with previous observational studies. Second, after the changes in cloud and radiative properties with SST anomaly are separated into dynamic, thermodynamic, and residual components, changes in the dynamic component (taken as the vertical velocity at 700 hPa) have relatively little effect on cloud and radiative properties. However, the estimated inversion strength decreases with increasing SST, accounting for a large portion of the measured decreases in cloud fraction and cloud optical depth. The residual positive change in net cloud radiative effect (1.48 W/m(exp 2)/ K) and small changes in low-cloud amount (-0.81% to 0.22% /K) and decrease in the logarithm of optical depth (-0.035 to -0.046/ K) with SST are interpreted as a positive cloud feedback, with cloud optical depth feedback being the dominant contributor. Last, the magnitudes of the residual changes differ greatly among the six low-cloud regions examined in this study, with the largest positive feedbacks (approximately 4 W/m(exp 2)/ K) in the southeast and northeast

  9. Cirrus heterogeneity effects on cloud optical properties retrieved with an optimal estimation method from MODIS VIS to TIR channels

    NASA Astrophysics Data System (ADS)

    Fauchez, T.; Platnick, S.; Sourdeval, O.; Meyer, K.; Cornet, C.; Zhang, Z.; Szczap, F.

    2017-02-01

    This study presents preliminary results on the effect of cirrus heterogeneities on top-of-atmosphere (TOA) simulated radiances or reflectances for MODIS channels centered at 0.86, 2.21, 8.56, 11.01 and 12.03 µm, and on cloud optical properties retrieved with a research-level optimal estimation method (OEM). Synthetic cirrus cloud fields are generated using a 3D cloud generator (3DCLOUD) and radiances/reflectances are simulated using a 3D radiative transfer code (3DMCPOL). We find significant differences between the heterogeneity effects on either visible and near-infrared (VNIR) or thermal infrared (TIR) radiances. However, when both wavelength ranges are combined, heterogeneity effects are dominated by the VNIR horizontal radiative transport effect. As a result, small optical thicknesses are overestimated and large ones are underestimated. Retrieved effective diameter are found to be slightly affected, contrarily to retrievals using TIR channels only.

  10. Frequency and causes of failed MODIS cloud property retrievals for liquid phase clouds over global oceans

    PubMed Central

    Cho, Hyoun‐Myoung; Meyer, Kerry; Lebsock, Matthew; Platnick, Steven; Ackerman, Andrew S.; Di Girolamo, Larry; C.‐Labonnote, Laurent; Cornet, Céline; Riedi, Jerome; Holz, Robert E.

    2015-01-01

    Abstract Moderate Resolution Imaging Spectroradiometer (MODIS) retrieves cloud droplet effective radius (r e) and optical thickness (τ) by projecting observed cloud reflectances onto a precomputed look‐up table (LUT). When observations fall outside of the LUT, the retrieval is considered “failed” because no combination of τ and r e within the LUT can explain the observed cloud reflectances. In this study, the frequency and potential causes of failed MODIS retrievals for marine liquid phase (MLP) clouds are analyzed based on 1 year of Aqua MODIS Collection 6 products and collocated CALIOP and CloudSat observations. The retrieval based on the 0.86 µm and 2.1 µm MODIS channel combination has an overall failure rate of about 16% (10% for the 0.86 µm and 3.7 µm combination). The failure rates are lower over stratocumulus regimes and higher over the broken trade wind cumulus regimes. The leading type of failure is the “r e too large” failure accounting for 60%–85% of all failed retrievals. The rest is mostly due to the “r e too small” or τ retrieval failures. Enhanced retrieval failure rates are found when MLP cloud pixels are partially cloudy or have high subpixel inhomogeneity, are located at special Sun‐satellite viewing geometries such as sunglint, large viewing or solar zenith angles, or cloudbow and glory angles, or are subject to cloud masking, cloud overlapping, and/or cloud phase retrieval issues. The majority (more than 84%) of failed retrievals along the CALIPSO track can be attributed to at least one or more of these potential reasons. The collocated CloudSat radar reflectivity observations reveal that the remaining failed retrievals are often precipitating. It remains an open question whether the extremely large r e values observed in these clouds are the consequence of true cloud microphysics or still due to artifacts not included in this study. PMID:27656330

  11. Evaluation of multi-layer cloud property retrievals from optimal estimation and Bayesian retrieval algorithms

    NASA Astrophysics Data System (ADS)

    Ding, Y.; Yang, P.

    2015-12-01

    Three physical and radiative cloud properties, namely, optical thickness (tau), effective diameter (De), and cloud top height(h) can be simultaneously inferred from IR radiances for multi-layer cloud cases. The retrieval algorithm implementation is based on a computationally efficient radiative transfer model and spaceborne measurements of narrowband infrared (IR) radiances at the top of the atmosphere. This study focuses on the evaluation of the retrieval results derived from two different algorithms, optimal estimation (OE) algorithm and Bayesian retrieval algorithm. Both of the two methods are able to offer comprehensive error analysis and quality flags. The evaluation results can potentially useful for retrieving the multi-layer clouds properties, a research subject that receives little attention. This presentation will discuss the pros and cons of retrieving cloud properties from the aforesaid retrieval algorithms.

  12. Study of the microphysical properties in stratus clouds on the Romanian Black Sea coast

    NASA Astrophysics Data System (ADS)

    Boscornea, Andreea; Stefan, Sabina; Sorin Vajaiac, Nicolae

    2016-04-01

    Stratocumulus clouds play a critical role in the Earth's climate system due to their spatial and temporal large extent. For this reason, this study aims to highlight the significant differences of microphysical properties of maritime and continental stratus clouds and By using the ATMOSLAB research aircraft were examined aerosol and microphysical properties, as well as the thermodynamics of the marine boundary layer in and around the Black Sea (between Mangalia, N: 43 48' 34,6'', E: 28̊ 35' 25,12'' and Navodari City N: 44̊ 19' 02'', E: 28̊ 36' 55,24''). More than 10 h measurements obtained by a Cloud Aerosol and Precipitation Spectrometer and the HAWKEYE included aerosol, CCN, cloud droplet and drizzle drop concentrations, air temperatures, liquid water content, real time cloud droplet and ice crystals images and marine aerosol measurements above the sea surface. The over 15 flight legs in clouds (minimum altitude 250 m and maximum altitude 4000 m) and the 4 flight legs performed directly above the sea surface (altitude 120 m) from the three flight 30 October 2015 and 23 November 2015 conducted to results that provide evidence of indirect aerosol effects associated with natural variability in the cloud and aerosol characteristics. For a complete understanding of the large-scale context processes maintaining and dissipating the continental and marine stratocumulus clouds information from a Sun Photometer (Eforie, N: 44̊ 04' 30'', E: 28̊ 37' 55'', altitude 40 m) and satellite data were used. The interpretation performed on the in situ (into cloud and below cloud) measured data have shown, as it was expected, differences between microphysical parameters for maritime and continental clouds and their dependence on aerosol concentrations. These presented results of in situ measurements of clouds above the Romanian Black Sea Coast are the first reported, so that more data is needed for an enhanced understanding of the maritime/continental microphysical contrasts in

  13. Variations of Cloud and Radiative Properties of Boundary-layer and Deep Convective Systems with Sea Surface Temperature Anomalies

    NASA Technical Reports Server (NTRS)

    Xu, Kuan-Man

    2010-01-01

    Gridded monthly-mean satellite data contain compositing information from different cloud system types and clear-sky environments. To isolate the variations of cloud physical properties of an individual cloud system type with its environment, orbital data are needed. In this study, we will analyze the variations of cloud and radiative properties of boundary-layer clouds and deep convective cloud systems with sea surface temperature (SST) anomalies. We use Terra-CERES (Clouds and the Earth s Radiant Energy System) Level 2 data to classify distinct cloud objects defined by cloud-system types (deep convection, boundary-layer cumulus, stratocumulus and overcast clouds), sizes, geographic locations, and matched large-scale environments. This analysis method identifies a cloud object as a contiguous region of the Earth with a single dominant cloud-system type. It determines the shape and size of the cloud object from the satellite data and the cloud-system selection criteria. The statistical properties of the identified cloud objects are analyzed in terms of probability density functions (PDFs) of a single property or joint PDFs between two properties. The SST anomalies are defined as the differences from five-year annual-cycle means. Individual cloud objects are sorted into one of five equal size subsets, with the matched SST anomalies ranging from the most negative to the most positive values, for a given size category of deep convective cloud objects, boundary-layer cumulus, stratocumulus and overcast cloud objects. The PDFs of cloud and radiative properties for deep convective cloud objects (between 30 S and 30 N) are found to largely similar among the five SST anomaly subsets except for the lowest SST anomaly subset. The different characteristics from this SST anomaly subset may be related to some cloud objects resulting from equatorward movement of extratropical cloud systems. This result holds true for all three different size categories (measured by equivalent

  14. Disk Evolution, Element Abundances and Cloud Properties of Young Gas Giant Planets

    PubMed Central

    Helling, Christiane; Woitke, Peter; Rimmer, Paul B.; Kamp, Inga; Thi, Wing-Fai; Meijerink, Rowin

    2014-01-01

    We discuss the chemical pre-conditions for planet formation, in terms of gas and ice abundances in a protoplanetary disk, as function of time and position, and the resulting chemical composition and cloud properties in the atmosphere when young gas giant planets form, in particular discussing the effects of unusual, non-solar carbon and oxygen abundances. Large deviations between the abundances of the host star and its gas giants seem likely to occur if the planet formation follows the core-accretion scenario. These deviations stem from the separate evolution of gas and dust in the disk, where the dust forms the planet cores, followed by the final run-away accretion of the left-over gas. This gas will contain only traces of elements like C, N and O, because those elements have frozen out as ices. ProDiMo protoplanetary disk models are used to predict the chemical evolution of gas and ice in the midplane. We find that cosmic rays play a crucial role in slowly un-blocking the CO, where the liberated oxygen forms water, which then freezes out quickly. Therefore, the C/O ratio in the gas phase is found to gradually increase with time, in a region bracketed by the water and CO ice-lines. In this regions, C/O is found to approach unity after about 5 Myrs, scaling with the cosmic ray ionization rate assumed. We then explore how the atmospheric chemistry and cloud properties in young gas giants are affected when the non-solar C/O ratios predicted by the disk models are assumed. The Drift cloud formation model is applied to study the formation of atmospheric clouds under the influence of varying premordial element abundances and its feedback onto the local gas. We demonstrate that element depletion by cloud formation plays a crucial role in converting an oxygen-rich atmosphere gas into carbon-rich gas when non-solar, premordial element abundances are considered as suggested by disk models. PMID:25370190

  15. Optical properties of marine stratocumulus clouds modified by ships

    NASA Technical Reports Server (NTRS)

    King, Michael D.; Radke, Lawrence F.; Hobbs, Peter V.

    1993-01-01

    Results are presented of an application of the diffusion domain method to multispectral solar radiation measurements obtained deep within a marine stratocumulus cloud layer modified by pollution from ships. In situ airborne measurements of the relative angular distribution of scattered radiation are compared to known asymptotic expressions for the intensity field deep within an optically thick cloud layer. Analytical expressions relating the ratio of the nadir-to-zenith intensities to surface reflectance, similarity parameter, and scaled optical depth beneath the aircraft flight level are used to analyze measurements obtained with the cloud absorption radiometer mounted on the University of Washington's C-131A research aircraft. It is shown that the total optical thickness of the cloud layer increased in the ship tracks, in contrast to the similarity parameter, which decreased. The decrease in absorption was a direct consequence of the reduction in cloud droplet size that occurred within the ship tracks.

  16. Inferring Selected Cloud Properties from Satellite Lightning Data

    NASA Technical Reports Server (NTRS)

    Schroeder, Vicki; Baker, M. B.

    1999-01-01

    The recent advent of satellite lightning detection programs has introduced a new potential for obtaining global information about other (hard to measure) cloud properties. We have made use of observations together with numerical model studies to show that positive correlations exist between: (1) lightning flashrate (F) and vertical velocity (w); and (2) flashrate (F) and the amount of condensate (water and ice) lofted through the -10 C isotherm (C(sub u)). The lightning flashrate appears to be very sensitive to the magnitude of the updraft velocity, with F increasing rapidly with w above a threshold of w approx. = 5-10 m/s. By contrast, we have found that the flashrate/condensate relationship appears to be approximately linear. We are currently refining the F-updraft and F-condensate relationships with further model studies before applying them to lightning data from the Optical Transient Detector (OTD) and the Lightning Imaging Sensor (LIS). We hope, with this method, to provide estimates of the large scale vertical water transport by continental convective systems over seasonal timescales.

  17. Improved retrievals of the optical properties of cirrus clouds by a combination of lidar methods.

    PubMed

    Cadet, Bertrand; Giraud, Vincent; Haeffelin, Martial; Keckhut, Philippe; Rechou, Anne; Baldy, Serge

    2005-03-20

    We focus on improvement of the retrieval of optical properties of cirrus clouds by combining two lidar methods. We retrieve the cloud's optical depth by using independently the molecular backscattering profile below and above the cloud [molecular integration (MI) method] and the backscattering profile inside the cloud with an a priori effective lidar ratio [particle integration (PI) method]. When the MI method is reliable, the combined MI-PI method allows us to retrieve the optimal effective lidar ratio. We compare these results with Raman lidar retrievals. We then use the derived optimal effective lidar ratio for retrieval with the PI method for situations in which the MI method cannot be applied.

  18. Intercomparison of independent estimates of cloud properties from simultaneous satellite observations

    NASA Technical Reports Server (NTRS)

    Coakley, J. A., Jr.; Chahine, M. T.; Susskind, J.

    1986-01-01

    Preliminary results are reported from comparisons between two techniques for determining the cloud cover fraction within a satellite remote sensing scene. One method (PRM) quantifies cloud-free and cloud-filled areas on the bases of physical relationships between temperature, humidity, cloud optical properties and emitted radiation. The other approach (RSSM) derives the fractional cover from the spatial structure of radiances detected by the sensor. The HIRS (PRM) and the AVHRR (RSSM) instruments, tuned to IR wavelengths, on the TIROS-N polar-orbiting satellite furnished the trial data. Sample results are provided from scans at 15 and 11 microns over the Pacific Ocean.

  19. Cloud-Vegetation Radiative Interaction: What Can We Learn from it about Cloud Optical Properties?

    NASA Technical Reports Server (NTRS)

    Marshak, Alexander; Knyazikhin, Yuri; Evans, Keith; Wiscombe, Warren

    2004-01-01

    Because of their radiative interactions, the vegetation canopy and the atmosphere are coupled together; each serves as a boundary condition to the radative transfer equations in the adjacent medium. To better understand radiative processes in these media we need an accurate description of their interactions. This presentation outlines a technique needed to describe interactions between vegetation and clouds and exploits it to retrieve cloud optical depth from ground-based radiance measurements. measurements of zenith radiance in the RED and NIR spectral regions. In addition to an algebraic combinations of spectral radiances such as Normalized Difference Cloud Index (NDCI) that can result in poor retrievals due to its insensitivity to cloud fraction, both RED and NIR radiances as points on the "RED vs. NIR" plane are proposed to be used for retrieval. The proposed method is applied to a multi-channel sunphotometer (as a part of AERONET) measurements at the ARM site in Oklahoma. In addition to cloud optical depth, the new method also infers a "radiatively effective" cloud fraction.

  20. Statistical retrieval of thin liquid cloud microphysical properties using ground-based infrared and microwave observations

    NASA Astrophysics Data System (ADS)

    Marke, Tobias; Ebell, Kerstin; Löhnert, Ulrich; Turner, David D.

    2016-12-01

    In this article, liquid water cloud microphysical properties are retrieved by a combination of microwave and infrared ground-based observations. Clouds containing liquid water are frequently occurring in most climate regimes and play a significant role in terms of interaction with radiation. Small perturbations in the amount of liquid water contained in the cloud can cause large variations in the radiative fluxes. This effect is enhanced for thin clouds (liquid water path, LWP <100 g/m2), which makes accurate retrieval information of the cloud properties crucial. Due to large relative errors in retrieving low LWP values from observations in the microwave domain and a high sensitivity for infrared methods when the LWP is low, a synergistic retrieval based on a neural network approach is built to estimate both LWP and cloud effective radius (reff). These statistical retrievals can be applied without high computational demand but imply constraints like prior information on cloud phase and cloud layering. The neural network retrievals are able to retrieve LWP and reff for thin clouds with a mean relative error of 9% and 17%, respectively. This is demonstrated using synthetic observations of a microwave radiometer (MWR) and a spectrally highly resolved infrared interferometer. The accuracy and robustness of the synergistic retrievals is confirmed by a low bias in a radiative closure study for the downwelling shortwave flux, even for marginally invalid scenes. Also, broadband infrared radiance observations, in combination with the MWR, have the potential to retrieve LWP with a higher accuracy than a MWR-only retrieval.

  1. Polar Cirrus Cloud Properties Through Long-Term Lidar and Radiometer Observations

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

    In comparison to mid latitude cloud cover, knowledge of polar cirrus and other cloud cover is limited. The interpretations of satellite-based cloud imaging and retrievals in polar regions have major problems due to factors such as darkness and extreme low temperatures. Beginning in 2002 a NASA orbiting lidar instrument, GLAS, (Geoscience Laser Altimeter System) will unambiguously define cloud type and fraction with good coverage of polar regions. Active laser sensing gives the spatial and temporal distribution of clouds and diamond dust. In preparation for, and supplementing the GLAS measurements are ground based MP (micro pulse) lidar experiments providing continuous profiling. MP lidar installations have been operating at the South Pole since December 1999 and at the Atmospheric Radiation Measurement (ARM) program arctic site since 1996. Both at the ARM Barrow, Alaska site and at the South Pole station, Fourier-transform interferometers also observe clouds in the wavelength intervals between approximately 5 and 18 microns. Spectral instruments can yield cloud microphysical properties with additional information from lidar about the vertical extent of clouds being modeled. We examine the simultaneous lidar and spectral data from both Barrow and South Pole, to obtain cloud properties (optical depth, particle size) by the use of both instruments. The results have applications to interpretation of current satellite data, and GLAS measurements when available.

  2. Optical properties of continental haze and cumulus and orographic clouds based on Space Shuttle polarimetric observations.

    PubMed

    Egan, W G; Israel, S; Sidran, M; Hindman, E E; Johnson, W R; Whitehead, V S

    1993-11-20

    Digitized Space Shuttle imagery in the red, green, and blue spectral regions (0.600, 0.540, and 0.435 µm, respectively) is used to characterize the mean radius and the index of refraction of droplets in cumulus and orographic clouds. The clouds are shown to consist concurrently of submicrometer and supermicrometer droplets, with the percent polarization indicative of the dominant sizes. Cloud development from haze as well as inhomogeneities in the cloud decks can be traced remotely. The absorption properties of clouds can also be determined remotely. An optical depth of continental haze in the same three spectral regions as the clouds is computed from the polarimetric and photometric contributions. Both Mie and Rayleigh scattering are included in the model.

  3. What are the Microphysical Properties of Clouds in an Atmosphere without Human-Induced Pollution?

    NASA Astrophysics Data System (ADS)

    Feichter, J.; O'Donnell, D.

    2009-04-01

    The composition of the atmosphere without any man-made emissions is controlled by biogenic and volcanic emissions and wind-driven particle emissions from the pedosphere and the ocean. Biogenic sources include phytoplankton, emission of volatile organic carbon (VOC) compounds by plants and reduced sulfur emissions from vegetation and soils. Besides mineral dust and biomass burning emissions, organics formed from biogenic VOC was likely the dominating aerosol over continents. The different chemical composition of present-day and past climate aerosol loading might affect the subset of aerosols acting as cloud condensation nuclei and subsequently the microphysical properties of clouds. We will present some exploratory model simulations contrasting the climate system in the absence of human-induced aerosol and VOC emissions with that in the presence of such emissions. In particular, cloud properties will be simulated for present-day emissions and contrasted to a scenario where anthropogenic emissions are switched off. The atmospheric general circulation model ECHAM5 used for this study includes the aerosol model HAM and has been extended by an emission model and a module for secondary organic aerosol (SOA). The updated model treats SOA formed from the anthropogenic precursors toluene, xylene and benzene and from the biogenic precursors isoprene and monoterpenes. SOA-specific modelled processes are precursor emissions, gas-phase formation of SOA and gas-aerosol phase partitioning of SOA. Aerosol microphysical and sink processes (dry and wet removal) are treated with minor modifications to the existing model. The VOC emissions from plants are calculated dependent on surface temperature and photosynthetically active radiation flux.

  4. Cloud properties derived from two lidars over the ARM SGP site

    SciTech Connect

    Dupont, Jean-Charles; Haeffelin, Martial; Morille, Y.; Comstock, Jennifer M.; Flynn, Connor J.; Long, Charles N.; Sivaraman, Chitra; Newsom, Rob K.

    2011-02-16

    [1] Active remote sensors such as lidars or radars can be used with other data to quantify the cloud properties at regional scale and at global scale (Dupont et al., 2009). Relative to radar, lidar remote sensing is sensitive to very thin and high clouds but has a significant limitation due to signal attenuation in the ability to precisely quantify the properties of clouds with a 20 cloud optical thickness larger than 3. In this study, 10-years of backscatter lidar signal data are analysed by a unique algorithm called STRucture of ATmosphere (STRAT, Morille et al., 2007). We apply the STRAT algorithm to data from both the collocated Micropulse lidar (MPL) and a Raman lidar (RL) at the Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) site between 1998 and 2009. Raw backscatter lidar signal is processed and 25 corrections for detector deadtime, afterpulse, and overlap are applied. (Campbell et al.) The cloud properties for all levels of clouds are derived and distributions of cloud base height (CBH), top height (CTH), physical cloud thickness (CT), and optical thickness (COT) from local statistics are compared. The goal of this study is (1) to establish a climatology of macrophysical and optical properties for all levels of clouds observed over the ARM SGP site 30 and (2) to estimate the discrepancies induced by the two remote sensing systems (pulse energy, sampling, resolution, etc.). Our first results tend to show that the MPLs, which are the primary ARM lidars, have a distinctly limited range where all of these cloud properties are detectable, especially cloud top and cloud thickness, but even actual cloud base especially during summer daytime period. According to the comparisons between RL and MPL, almost 50% of situations show a signal to noise ratio too low (smaller than 3) for the MPL in order to detect clouds higher than 7km during daytime period in summer. Consequently, the MPLderived annual cycle of cirrus cloud base (top) altitude is

  5. Venus cloud properties: Infrared opacity and mass mixing ratio

    NASA Technical Reports Server (NTRS)

    Samuelson, R. E.; Hanel, R. A.; Herath, L. W.; Kunde, V. G.; Maguire, W. C.

    1974-01-01

    By using the Mariner 5 temperature profile and a homogeneous cloud model, and assuming that CO2 and cloud particles are the only opacity sources, the wavelength dependence of the Venus cloud opacity is inferred from the infrared spectrum of the planet between 450 and 1250/cm. Justification for applying the homogeneous cloud model is found in the fact that numerous polarization and infrared data are mutually consistent within the framework of such a model; on the other hand, dense cloud models are not satisfactory. Volume extinction coefficients varying from 0.000005 to 0.000015/cm depending on the wavelength, are determined at the tropopause level of 6110 km. By using all available data, a cloud mass mixing ratio of approximately 0.000005 and a particle concentration of about 900 particles per cu cm at this level are also inferred. The derived cloud opacity compares favorably with that expected for a haze of droplets of a 75% aqueous solution of sulfuric acid.

  6. Aerosol impacts on radiative and microphysical properties of clouds and precipitation formation

    NASA Astrophysics Data System (ADS)

    Alizadeh-Choobari, O.; Gharaylou, M.

    2017-03-01

    Through modifying the number concentration and size of cloud droplets, aerosols have intricate impacts on radiative and microphysical properties of clouds, which together influence precipitation processes. Aerosol-cloud interactions for a mid-latitude convective cloud system are investigated using a two-moment aerosol-aware bulk microphysical scheme implemented into the Weather Research and Forecasting (WRF) model. Three sensitivity experiments with initial identical dynamic and thermodynamic conditions, but different cloud-nucleating aerosol concentrations were conducted. Increased aerosol number concentration has resulted in more numerous cloud droplets of overall smaller sizes, through which the optical properties of clouds have been changed. While the shortwave cloud forcing is significantly increased in more polluted experiments, changes in the aerosol number concentration have negligible impacts on the longwave cloud forcing. For the first time, it is found that polluted clouds have higher cloud base heights, the feature that is caused by more surface cooling due to a higher shortwave cloud forcing, as well as a drier boundary layer in the polluted experiment compared to the clean. The polluted experiment was also associated with a higher liquid water content (LWC), caused by an increase in the number of condensation of water vapor due to higher concentration of hygroscopic aerosols acting as condensation nuclei. The domain-averaged accumulated precipitation is little changed under both polluted and clean atmosphere. Nevertheless, changes in the rate of precipitation are identified, such that under polluted atmosphere light rain is reduced, while both moderate and heavy rain are intensified, confirming the fact that if an ample influx of water vapor exists, an increment of hygroscopic aerosols can increase the amount of precipitation.

  7. Inference of cloud altitude and optical properties from MAX-DOAS measurements

    NASA Astrophysics Data System (ADS)

    Nasse, Jan-Marcus; Zielcke, Johannes; Frieß, Udo; Lampel, Johannes; König-Langlo, Gert; Platt, Ulrich

    2015-04-01

    Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) is a widely used technique for the detection of atmospheric trace gases, e.g. NO2, SO2, BrO, HCHO, but also for the oxygen collision complex O4. The atmospheric distribution of the latter is proportional to the square of the molecular oxygen concentration and thus well known. By comparing measured O4 differential slant column densities (dSCDs) from MAX-DOAS measurements with modeled ones, information on aerosol distributions and optical properties, as well as on clouds can be obtained using an algorithm based on optimal estimation. Here the ability of MAX-DOAS observations to detect cloud altitude and cloud optical properties of different cloud covers based on measurements of O4 will be discussed. The analysis uses measurements made by a ship-borne instrument on two cruises of the German research vessel Polarstern to the Antarctic Weddell Sea from June to October 2013. During this time a broad range of cloud and aerosol conditions was encountered, in particular persistent low cloud cover with a high optical thickness. Aerosol and particle extinction profiles were retrieved with temporal resolutions of up to 15 minutes. For clouds at altitudes up to 2000 m the results show a very good agreement with co-located measurements of a commercial ceilometer and pictures from a cloud camera. Unless visibility was very poor due to fog, even rapid changes in cloud altitude or cover could be detected by MAX-DOAS. These results indicate that under homogeneous cloud cover an accurate retrieval of trace gas vertical profiles can be possible despite the strong influence of clouds on atmospheric light paths. We will discuss advantages and limitations of cloud detection with MAX-DOAS, implications for the subsequent retrieval of trace gas profiles and the possible use of external (ceilometer) data as a priori information for the profile retrieval algorithm.

  8. Microphysical Properties of Single and Mixed-Phase Arctic Clouds Derived from AERI Observations

    SciTech Connect

    Turner, David D.

    2003-06-01

    A novel new approach to retrieve cloud microphysical properties from mixed-phase clouds is presented. This algorithm retrieves cloud optical depth, ice fraction, and the effective size of the water and ice particles from ground-based, high-resolution infrared radiance observations. The theoretical basis is that the absorption coefficient of ice is stronger than that of liquid water from 10-13 mm, whereas liquid water is more absorbing than ice from 16-25 um. However, due to strong absorption in the rotational water vapor absorption band, the 16-25 um spectral region becomes opaque for significant water vapor burdens (i.e., for precipitable water vapor amounts over approximately 1 cm). The Arctic is characterized by its dry and cold atmosphere, as well as a preponderance of mixed-phase clouds, and thus this approach is applicable to Arctic clouds. Since this approach uses infrared observations, cloud properties are retrieved at night and during the long polar wintertime period. The analysis of the cloud properties retrieved during a 7 month period during the Surface Heat Budget of the Arctic (SHEBA) experiment demonstrates many interesting features. These results show a dependence of the optical depth on cloud phase, differences in the mode radius of the water droplets in liquid-only and mid-phase clouds, a lack of temperature dependence in the ice fraction for temperatures above 240 K, seasonal trends in the optical depth with the clouds being thinner in winter and becoming more optically thick in the late spring, and a seasonal trend in the effective size of the water droplets in liquid-only and mixed-phase clouds that is most likely related to aerosol concentration.

  9. A 19-Month Climatology of Marine Aerosol-Cloud-Radiation Properties Derived From DOE ARM AMF Deployment at the Azores: Part I: Cloud Fraction and Single-Layered MBL Cloud Properties

    NASA Technical Reports Server (NTRS)

    Dong, Xiquan; Xi, Baike; Kennedy, Aaron; Minnis, Patrick; Wood, Robert

    2013-01-01

    A 19-month record of total, and single-layered low (0-3 km), middle (3-6 km), and high (> 6 km) cloud fractions (CFs), and the single-layered marine boundary layer (MBL) cloud macrophysical and microphysical properties has been generated from ground-based measurements taken at the ARM Azores site between June 2009 and December 2010. It documents the most comprehensive and longest dataset on marine cloud fraction and MBL cloud properties to date. The annual means of total CF, and single-layered low, middle, and high CFs derived from ARM radar-lidar observations are 0.702, 0.271, 0.01 and 0.106, respectively. More total and single-layered high CFs occurred during winter, while single-layered low CFs were greatest during summer. The diurnal cycles for both total and low CFs are stronger during summer than during winter. The CFs are bimodally distributed in the vertical with a lower peak at approx. 1 km and higher one between 8 and 11 km during all seasons, except summer, when only the low peak occurs. The persistent high pressure and dry conditions produce more single-layered MBL clouds and fewer total clouds during summer, while the low pressure and moist air masses during winter generate more total and multilayered-clouds, and deep frontal clouds associated with midlatitude cyclones.

  10. Fast methods of computing bulk radiative properties of inhomogeneous clouds illuminated by solar radiation

    SciTech Connect

    Gabriel, P.

    1995-09-01

    The use of cloud fraction as a means of incorporating horizontal cloud inhomogeneity in radiative transfer calculations is widespread in the atmospheric science community. This research attempts to bypass the use of cloud fraction in radiative transfer modeling for two-dimensional media. Gabriel describes two approximation techniques useful in calculating the domain averaged bulk radiative properties such as albedo, flux divergence and mean radiance that dispense with the need to use cloud fraction as a specifier of cloud inhomogeneity. The results suggest that the variability of the medium can largely be accounted for through the pseudo-source term, offering hope of parameterizing the equation of transfer in terms of the statistical properties of the medium. 1 fig.

  11. Understanding the Effect of Aerosol Properties on Cloud Droplet Formation during TCAP Field Campaign Report

    SciTech Connect

    Cziczo, Daniel

    2016-05-01

    The formation of clouds is an essential element in understanding the Earth’s radiative budget. Liquid water clouds form when the relative humidity exceeds saturation and condensedphase water nucleates on atmospheric particulate matter. The effect of aerosol properties such as size, morphology, and composition on cloud droplet formation has been studied theoretically as well as in the laboratory and field. Almost without exception these studies have been limited to parallel measurements of aerosol properties and cloud formation or collection of material after the cloud has formed, at which point nucleation information has been lost. Studies of this sort are adequate when a large fraction of the aerosol activates, but correlations and resulting model parameterizations are much more uncertain at lower supersaturations and activated fractions.

  12. Radiative and microphysical properties of Arctic stratus clouds from multiangle downwelling infrared radiances

    NASA Astrophysics Data System (ADS)

    Rathke, Carsten; Neshyba, Steven; Shupe, Matthew D.; Rowe, Penny; Rivers, Aaron

    2002-12-01

    The information content of multiangle downwelling infrared radiance spectra of stratus clouds is investigated. As an example, 76 sets of spectra were measured at angles of 0, 15, 30 and 45° from zenith, using an interferometer based at the Surface Heat Budget of the Arctic Ocean (SHEBA) drifting ice camp. Exploiting the angular variation of radiance in infrared microwindows, a "geometric" algorithm is used to determine cloud temperature and optical depth without auxiliary information. For comparison, a spectral method allows us to infer cloud microphysical properties for each angle; each multiangle set therefore constitutes a microphysical characterization of horizontal inhomogeneity of the cloudy scene. We show that cloud temperatures determined with both approaches agree with temperatures obtained from lidar/radiosonde data. The multiangle radiance observations can also be used to calculate the longwave flux reaching the surface. We find that up to 14 W m-2 of the overcast fluxes can be attributed to horizontal variations in cloud microphysical properties.

  13. Determinants of Low Cloud Properties - An Artificial Neural Network Approach Using Observation Data Sets

    NASA Astrophysics Data System (ADS)

    Andersen, Hendrik; Cermak, Jan

    2015-04-01

    This contribution studies the determinants of low cloud properties based on the application of various global observation data sets in machine learning algorithms. Clouds play a crucial role in the climate system as their radiative properties and precipitation patterns significantly impact the Earth's energy balance. Cloud properties are determined by environmental conditions, as cloud formation requires the availability of water vapour ("precipitable water") and condensation nuclei in sufficiently saturated conditions. A main challenge in the research of aerosol-cloud interactions is the separation of aerosol effects from meteorological influence. To gain understanding of the processes that govern low cloud properties in order to increase accuracy of climate models and predictions of future changes in the climate system is thus of great importance. In this study, artificial neural networks are used to relate a selection of predictors (meteorological parameters, aerosol loading) to a set of predictands (cloud microphysical and optical properties). As meteorological parameters, wind direction and velocity, sea level pressure, static stability of the lower troposphere, atmospheric water vapour and temperature at the surface are used (re-analysis data by the European Centre for Medium-Range Weather Forecasts). In addition to meteorological conditions, aerosol loading is used as a predictor of cloud properties (MODIS collection 6 aerosol optical depth). The statistical model reveals significant relationships between predictors and predictands and is able to represent the aerosol-cloud-meteorology system better than frequently used bivariate relationships. The most important predictors can be identified by the additional error when excluding one predictor at a time. The sensitivity of each predictand to each of the predictors is analyzed.

  14. 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.

  15. The ESA Cloud_cci project: generation of multi-decadal, consistent, global data sets of cloud properties with uncertainty information

    NASA Astrophysics Data System (ADS)

    Stapelberg, Stefan; Finkensieper, Stephan; Stengel, Martin; Schlundt, Cornelia; Sus, Oliver; Hollmann, Rainer; Poulsen, Caroline; ESA Cloud cci Team

    2016-04-01

    In 2010 the ESA Climate Change Initiative (CCI) Cloud project was started along with 12 other CCI projects covering atmospheric, oceanic and terrestrial "essential climate variables (ECV)". The main goal is the generation of satellite-based climate data records that meet the challenging requirements of the Global Climate Observing System. The objective target within the ESA Cloud_cci project is the generation of long-term coherent cloud property datasets covering 33 years that also provide mathematically consistent uncertainty information following the optimal estimation (OE) retrieval theory. The cloud properties considered are cloud mask, cloud top level estimates, cloud thermodynamic phase, cloud optical thickness, cloud effective radius and post processed parameters such as cloud liquid and ice water path. In this presentation we will discuss the benefit of using an optimal estimation retrieval framework, which provides consistence among the retrieved cloud variables and pixel-based uncertainty estimates based on different passive instruments such as AVHRR, MODIS and AATSR. We will summarize the results of the project so far along with ongoing further developments that currently take place. Our results will be compared with other well-established satellite data records, surface observations and cloud climatologies (e.g., PATMOS-X, ISCCP, CLARA-A2, MODIS collection 6, SYNOP). These inter-comparison results will indicate the strengths and weaknesses of the Cloud_cci datasets. Finally, we will present long-term time series of the retrieved cloud variables for AVHRR (1982-2014) that enable global, multi-decadal analyses of clouds.

  16. The ESA Cloud_cci Project: Generation of Multi-Decadal, Consistent, Global Data Sets of Cloud Properties with Uncertainty Information

    NASA Astrophysics Data System (ADS)

    Stapelberg, S.; Stengel, M.; Schlundt, C.; Sus, O.; Hollmann, R.; Poulsen, C. A.

    2015-12-01

    In 2010 the ESA Climate Change Initiative (CCI) Cloud project was started along with 12 other CCI projects covering atmospheric, oceanic and terrestrial "essential climate variables (ECV)". The main goal is the generation of satellite-based climate data records that meet the challenging requirements of the Global Climate Observing System. The objective target within the ESA Cloud_cci project is the generation of long-term coherent cloud property datasets covering 33 years that also provide mathematically consistent uncertainty information following the optimal estimation (OE) retrieval theory. The cloud properties considered are cloud mask, cloud top level estimates, cloud thermodynamic phase, cloud optical thickness, cloud effective radius and post processed parameters such as cloud liquid and ice water path. In this presentation we will discuss the benefit of using an optimal estimation retrieval framework, which provides consistence among the retrieved cloud variables and pixel-based uncertainty estimates based on different passive instruments such as AVHRR, MODIS and AATSR. We will summarize the results of the project so far along with ongoing further developments that currently take place. Our results will be compared with other well-established satellite data records, surface observations and cloud climatologies (e.g., PATMOS-X, ISCCP, CLARA-A2, MODIS collection 6, SYNOP). These inter-comparison results will indicate the strengths and weaknesses of the Cloud_cci datasets. Finally, we will present long-term time series of the retrieved cloud variables for AVHRR (1982-2014) that enable global, multi-decadal analyses of clouds.

  17. The role of organic compounds in cloud formation: Relative importance of entrainment, co-condensation and particle-phase properties

    NASA Astrophysics Data System (ADS)

    Lowe, Samuel; Partridge, Daniel; Topping, David; Riipinen, Ilona

    2016-04-01

    The organic fraction of atmospheric aerosols is widely acknowledged to affect the cloud nucleating potential of aerosols. Cloud droplet formation through activation of non-volatile CCN is considered to be relatively well understood, however, there are fewer systematic studies on the activation of aerosols containing semi-volatile organic compounds that co-condense alongside water vapour, thus enhancing CCN activity. Although the significance of co-condensation of organic vapours for cloud droplet number concentration predictions has recently been identified, it remains uncertain how this process may interact with atmospheric dynamics. In addition to co-condensation of existing in-cloud material, additional semi-volatile mass can be entrained from the surrounding environment. Reduced cloud droplet number concentrations are expected as the parcel is diluted with clean air; however, additional soluble mass in the particle phase promotes droplet activation. The extent of increased droplet activation due to co-condensation relies also on the physiochemical properties of the organic compounds, as seen in several other phase partitioning sensitivity studies. In this work we study the simultaneous impact of entrainment and co-condensation, the relative importance of these two processes at different atmospheric conditions, their interactions with each other, and the particle-phase chemistry in terms of cloud microphysical properties and their parametric sensitivities. To assess the importance of the entrainment of semi-volatile materials as compared with their co-condensation and chemical properties, a pseudo-adiabatic cloud parcel model with a detailed description of bin microphysics is employed. We have added the co-condensation process to the model such that it is coupled with the parametric entrainment representation. The effects of entrainment and co-condensation are benchmarked independently and simultaneously against a control simulation. Furthermore, we probe the

  18. Observations of regional and local variability in the optical properties of maritime clouds

    SciTech Connect

    White, A.B.

    1996-04-01

    White and Fairall (1995) calculated the optical properties of the marine boundary layer (MBL) clouds observed during the Atlantic Stratocumulus Transition Experiment (ASTEX) and compared their results with the results obtained by Fairall et al. for the MBL clouds observed during the First International Satellite Climatology Program (ISSCP) Regional Experiment (FIRE). They found a factor of two difference in the optical depth versus liquid water relationship that applies to the clouds observed in each case. In the present study, we present evidence to support this difference. We also investigate the local variability exhibited in the ASTEX optical properties using measurements of the boundary layer aerosol concentration.

  19. Diurnal, Seasonal, and Interannual Variations of Cloud Properties Derived for CERES From Imager Data

    NASA Technical Reports Server (NTRS)

    Minnis, Patrick; Young, David F.; Sun-Mack, Sunny; Trepte, Qing Z.; Chen, Yan; Brown, Richard R.; Gibson, Sharon; Heck, Patrick W.

    2004-01-01

    Simultaneous measurement of the radiation and cloud fields on a global basis is a key component in the effort to understand and model the interaction between clouds and radiation at the top of the atmosphere, at the surface, and within the atmosphere. The NASA Clouds and Earth s Radiant Energy System (CERES) Project, begun in 1998, is meeting this need. Broadband shortwave (SW) and longwave radiance measurements taken by the CERES scanners at resolutions between 10 and 20 km on the Tropical Rainfall Measuring Mission (TRMM), Terra, and Aqua satellites are matched to simultaneous retrievals of cloud height, phase, particle size, water path, and optical depth OD from the TRMM Visible Infrared Scanner (VIRS) and the Moderate Resolution Imaging Spectroradiometer (MODIS) on Terra and Aqua. Besides aiding the interpretation of the broadband radiances, the CERES cloud properties are valuable for understanding cloud variations at a variety of scales. In this paper, the resulting CERES cloud data taken to date are averaged at several temporal scales to examine the temporal and spatial variability of the cloud properties on a global scale at a 1 resolution.

  20. The Shortwave Spectroradiometer as a Versatile Sensor for Observation of Cloud Optical and Microphysical Properties

    NASA Astrophysics Data System (ADS)

    Lubin, D.; Vogelmann, A. M.; Flynn, C. J.

    2013-12-01

    Recent years have seen the advent of shortwave spectroradiometers covering the ultraviolet through near-infrared parts of the spectrum. With multiple linear-array detectors, spectral coverage as wide as 350-2200 nanometers is possible. In this wide spectral interval, the downwelling irradiance is sensitive - in contrasting atmospheric windows - to surface albedo, cloud optical depth, cloud thermodynamic phase, and effective droplet/particle size. For climatological studies relevant to climate model improvement, a shortwave spectroradiometer offers four significant advantages. First, full spectral observations can be made at high time resolution, often in one-minute averages. This enables study of cloud formation, evolution, and dissipation, in response to meteorological and aerosol forcing. Second, with shortwave spectral data cloud properties can be derived for a wide range of liquid water content; in contrast to the middle-infrared window where only optically thin clouds can be studied. Third, commercial technology is now available - including some instruments nearly entirely ready for atmospheric application - that make the acquisition cost of a spectroradiometer relatively modest compared to other types of advanced atmospheric instrumentation. This offers the possibility of developing ground-based networks for geographically distributed measurements. Fourth, measurement of the downwelling spectral irradiance enables direct empirical interpretation of cloud properties' influence on the surface radiation budget. We have experience with shortwave spectroradiometer deployment in the high Arctic, at the US Department of Energy Atmospheric Radiation Measurement (ARM) program Southern Great Plains (SGP) site, and at Ross Island, Antarctica. These measurements reveal a great diversity in cloud properties, including extensive Arctic mixed-phase cloud during springtime, rapidly evolving liquid water cloud at SGP, and ice-dominated cloud in response to moisture traversing

  1. Coupling Between Oceanic Upwelling and Cloud-aerosol Properties at the AMF Point Reyes Site

    SciTech Connect

    Dunn, M.; Jensen, M.; Miller, M.; Kollias, P.; Bartholomew, M. J.; Turner, D.; Andrews, E.; Jefferson, A.; Daum, P.

    2008-03-10

    Cloud microphysical properties measured at the ARM Mobile Facility site located on the northern coast of California near Point Reyes, during the 2005 Marine Stratus Radiation, Aerosol and Drizzle experiment, were analyzed to determine their relationship to the coastal sea surface temperature (SST) which was characterized using measurements acquired from a National Oceanic and Atmospheric Administration offshore buoy. An increase in SST resulting from a relaxation of upwelling, occurring in the eastern Pacific Ocean off the coast of California in summer is observed to strongly correlate with nearby ground measured cloud microphysical properties and cloud condensation nuclei (CCN) concentrations. Correlations between these atmospheric and oceanic features provide insight into the interplay between the ocean and cloud radiative properties. We present evidence of this robust correlation and examine the factors controlling these features. The marine boundary layer is in direct contact with the sea surface and is strongly influenced by SST. Moisture and vertical motion are crucial ingredients for cloud development and so we examine the role of SST in providing these key components to the atmosphere. Although upwelling of cold subsurface waters is conventionally thought to increase aerosols in the region, thus increasing clouds, here we observed a relaxation of upwelling associated with changes in the structure of marine stratus clouds. As upwelling relaxes, the SST get warmer, thick clouds with high liquid water paths are observed and persist for a few days. This cycle is repeated throughout the summer upwelling season. A concomitant cyclic increase and decrease of CCN concentration is also observed. Forcing mechanisms and large-scale atmospheric features are discussed. Marine stratocumulus clouds are a critical component of the earth's radiation budget and this site provides an excellent opportunity to study the influence of SST on these clouds.

  2. Cloud-Driven Changes in Aerosol Optical Properties - Final Technical Report

    SciTech Connect

    Ogren, John A.; Sheridan, Patrick S.; Andrews, Elisabeth

    2007-09-30

    The optical properties of aerosol particles are the controlling factors in determining direct aerosol radiative forcing. These optical properties depend on the chemical composition and size distribution of the aerosol particles, which can change due to various processes during the particles’ lifetime in the atmosphere. Over the course of this project we have studied how cloud processing of atmospheric aerosol changes the aerosol optical properties. A counterflow virtual impactor was used to separate cloud drops from interstitial aerosol and parallel aerosol systems were used to measure the optical properties of the interstitial and cloud-scavenged aerosol. Specifically, aerosol light scattering, back-scattering and absorption were measured and used to derive radiatively significant parameters such as aerosol single scattering albedo and backscatter fraction for cloud-scavenged and interstitial aerosol. This data allows us to demonstrate that the radiative properties of cloud-processed aerosol can be quite different than pre-cloud aerosol. These differences can be used to improve the parameterization of aerosol forcing in climate models.

  3. Factors influencing the microphysics and radiative properties of liquid-dominated Arctic clouds: insight from observations of aerosol and clouds during ISDAC

    SciTech Connect

    Earle, Michael; Liu, Peter S.; Strapp, J. Walter; Zelenyuk, Alla; Imre, D.; McFarquhar, Greg; Shantz, Nicole C.; Leaitch, W. R.

    2011-11-04

    Aircraft measurements during the Indirect and Semi-Direct Aerosol Campaign (ISDAC) in April 2008 are used to investigate aerosol indirect effects in Arctic clouds. Two aerosol-cloud regimes are considered in this analysis: single-layer stratocumulus cloud with below-cloud aerosol concentrations (N{sub a}) below 300 cm{sup -3} on April 8 and April 26-27 (clean cases); and inhomogeneous layered cloud with N{sub a} > 500 cm{sup -3} below cloud base on April 19-20, concurrent with a biomass burning episode (polluted cases). Vertical profiles through cloud in each regime are used to determine average cloud microphysical and optical properties. Positive correlations between the cloud droplet effective radius (Re) and cloud optical depth ({tau}) are observed for both clean and polluted cases, which are characteristic of optically-thin, non-precipitating clouds. Average Re values for each case are {approx} 6.2 {mu}m, despite significantly higher droplet number concentrations (Nd) in the polluted cases. The apparent independence of Re and Nd simplifies the description of indirect effects, such that {tau} and the cloud albedo (A) can be described by relatively simple functions of the cloud liquid water path. Adiabatic cloud parcel model simulations show that the marked differences in Na between the regimes account largely for differences in droplet activation, but that the properties of precursor aerosol also play a role, particularly for polluted cases where competition for vapour amongst the more numerous particles limits activation to larger and/or more hygroscopic particles. The similarity of Re for clean and polluted cases is attributed to compensating droplet growth processes for different initial droplet size distributions.

  4. Cloud Optical Properties from the Multifilter Shadowband Radiometer (MFRSRCLDOD). An ARM Value-Added Product

    SciTech Connect

    Turner, D. D.; McFarlane, S. A.; Riihimaki, L.; Shi, Y.; Lo, C.; Min, Q.

    2014-02-01

    The microphysical properties of clouds play an important role in studies of global climate change. Observations from satellites and surface-based systems have been used to infer cloud optical depth and effective radius. Min and Harrison (1996) developed an inversion method to infer the optical depth of liquid water clouds from narrow band spectral Multifilter Rotating Shadowband Radiometer (MFRSR) measurements (Harrison et al. 1994). Their retrieval also uses the total liquid water path (LWP) measured by a microwave radiometer (MWR) to obtain the effective radius of the warm cloud droplets. Their results were compared with Geostationary Operational Environmental Satellite (GOES) retrieved values at the Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) site (Min and Harrison 1996). Min et al. (2003) also validated the retrieved cloud optical properties against in situ observations, showing that the retrieved cloud effective radius agreed well with the in situ forward scattering spectrometer probe observations. The retrieved cloud optical properties from Min et al. (2003) were used also as inputs to an atmospheric shortwave model, and the computed fluxes were compared with surface pyranometer observations.

  5. Tillage system affects microbiological properties of soil

    NASA Astrophysics Data System (ADS)

    Delgado, A.; de Santiago, A.; Avilés, M.; Perea, F.

    2012-04-01

    Soil tillage significantly affects organic carbon accumulation, microbial biomass, and subsequently enzymatic activity in surface soil. Microbial activity in soil is a crucial parameter contributing to soil functioning, and thus a basic quality factor for soil. Since enzymes remain soil after excretion by living or disintegrating cells, shifts in their activities reflect long-term fluctuations in microbial biomass. In order to study the effects of no-till on biochemical and microbiological properties in comparison to conventional tillage in a representative soil from South Spain, an experiment was conducted since 1982 on the experimental farm of the Institute of Agriculture and Fisheries Research of Andalusia (IFAPA) in Carmona, SW Spain (37o24'07''N, 5o35'10''W). The soil at the experimental site was a very fine, montomorillonitic, thermic Chromic Haploxerert (Soil Survey Staff, 2010). A randomized complete block design involving three replications and the following two tillage treatments was performed: (i) Conventional tillage, which involved mouldboard plowing to a depth of 50 cm in the summer (once every three years), followed by field cultivation to a depth of 15 cm before sowing; crop residues being burnt, (ii) No tillage, which involved controlling weeds before sowing by spraying glyphosate and sowing directly into the crop residue from the previous year by using a planter with double-disk openers. For all tillage treatments, the crop rotation (annual crops) consisted of winter wheat, sunflower, and legumes (pea, chickpea, or faba bean, depending on the year), which were grown under rainfed conditions. Enzymatic activities (ß-glucosidase, dehydrogenase, aryl-sulphatase, acid phosphatase, and urease), soil microbial biomass by total viable cells number by acridine orange direct count, the density of cultivable groups of bacteria and fungi by dilution plating on semi-selective media, the physiological profiles of the microbial communities by BiologR, and the

  6. The Morphological Composite Product of Cloud Properties for Alaska

    NASA Astrophysics Data System (ADS)

    Wimmers, A. J.; Heidinger, A. K.

    2014-12-01

    Here we will present a new technique of satellite image compositing, supported by NOAA for producing and visualizing cloud products in the Alaska region. This technique, dubbed morphological compositing, is applied to a set of polar and geostationary satellite cloud products (CLAVR-x and GSIP) to create natural, real-time, high temporal resolution animations at the high latitudes. Other existing approaches for compositing satellite imagery from multiple sources produce imagery that, first and foremost, present the latest observations where available. The normal consequence of these approaches is a set of images with suboptimal temporal continuity (where continuity means natural motion, consistent resolution and correct location at the image time). Until recently this was understood to be inevitable at the high latitudes. However, the high sampling rate of cloud characteristics poleward of 70 degrees latitude (from four NOAA AVHRR sensors and two Metop AVHRR sensors) provides enough information for a more advanced compositing approach. The technique presented here uses an "optical flow" algorithm to estimate the object motion of clouds in between polar satellite observations and produce accurate, full-resolution imagery at 30-minute resolution. The resulting product can be interpreted just like geostationary imagery, and is in fact seamlessly combined with GOES-West cloud products in the final compositing stage. In addition, we will discuss the operational plans for the product starting in early 2015, as well as the possibilities for other related applications.

  7. Simultaneous Retrieval of Aerosol and Cloud Properties During the MILAGRO Field Campaign

    NASA Technical Reports Server (NTRS)

    Knobelspiesse, K.; Cairns, B.; Redemann, J.; Bergstrom, R. W.; Stohl, A.

    2011-01-01

    Estimation of Direct Climate Forcing (DCF) due to aerosols in cloudy areas has historically been a difficult task, mainly because of a lack of appropriate measurements. Recently, passive remote sensing instruments have been developed that have the potential to retrieve both cloud and aerosol properties using polarimetric, multiple view angle, and multi spectral observations, and therefore determine DCF from aerosols above clouds. One such instrument is the Research Scanning Polarimeter (RSP), an airborne prototype of a sensor on the NASA Glory satellite, which unfortunately failed to reach orbit during its launch in March of 2011. In the spring of 2006, the RSP was deployed on an aircraft based in Veracruz, Mexico, as part of the Megacity Initiative: Local and Global Research Observations (MILAGRO) field campaign. On 13 March, the RSP over flew an aerosol layer lofted above a low altitude marine stratocumulus cloud close to shore in the Gulf of Mexico. We investigate the feasibility of retrieving aerosol properties over clouds using these data. Our approach is to first determine cloud droplet size distribution using the angular location of the cloud bow and other features in the polarized reflectance. The selected cloud was then used in a multiple scattering radiative transfer model optimization to determine the aerosol optical properties and fine tune the cloud size distribution. In this scene, we were able to retrieve aerosol optical depth, the fine mode aerosol size distribution parameters and the cloud droplet size distribution parameters to a degree of accuracy required for climate modeling. This required assumptions about the aerosol vertical distribution and the optical properties of the coarse aerosol size mode. A sensitivity study was also performed to place this study in the context of future systematic scanning polarimeter observations, which found that the aerosol complex refractive index can also be observed accurately if the aerosol optical depth is

  8. Physical and chemical properties of industrial mineral oils affecting lubrication

    SciTech Connect

    Godfrey, D.; Herguth, W.R.

    1996-02-01

    The lubricating properties of mineral oils, and contaminants which affect those properties, are discussed. A contaminant is any material not in the original fresh oil, whether it is generated within the system or ingested. 5 refs.

  9. Physical and chemical properties of industrial mineral oils affecting lubrication

    SciTech Connect

    Godfrey, D.; Herguth, W.R.

    1995-05-01

    The physical and chemical properties of mineral oils that affect lubrication are reviewed. Recognition of these properties is useful for designing lubrication systems, diagnostics, friction and wear problems, and selecting appropriate test methods.

  10. Morphology and mixing state of atmospheric particles: Links to optical properties and cloud processing

    NASA Astrophysics Data System (ADS)

    China, Swarup

    Atmospheric particles are ubiquitous in Earth's atmosphere and impact the environment and the climate while affecting human health and Earth's radiation balance, and degrading visibility. Atmospheric particles directly affect our planet's radiation budget by scattering and absorbing solar radiation, and indirectly by interacting with clouds. Single particle morphology (shape, size and internal structure) and mixing state (coating by organic and inorganic material) can significantly influence the particle optical properties as well as various microphysical processes, involving cloud-particle interactions and including heterogeneous ice nucleation and water uptake. Conversely, aerosol cloud processing can affect the morphology and mixing of the particles. For example, fresh soot has typically an open fractal-like structure, but aging and cloud processing can restructure soot into more compacted shapes, with different optical and ice nucleation properties. During my graduate research, I used an array of electron microscopy and image analysis tools to study morphology and mixing state of a large number of individual particles collected during several field and laboratory studies. To this end, I investigated various types of particles such as tar balls (spherical carbonaceous particles emitted during biomass burning) and dust particles, but with a special emphasis on soot particles. In addition, I used the Stony Brook ice nucleation cell facility to investigate heterogeneous ice nucleation and water uptake by long-range transported particles collected at the Pico Mountain Observatory, in the Archipelago of the Azores. Finally, I used ice nucleation data from the SAAS (Soot Aerosol Aging Study) chamber study at the Pacific Northwest National Laboratory to understand the effects that ice nucleation and supercooled water processing has on the morphology of residual soot particles. Some highlights of our findings and implications are discussed next. We found that the

  11. A study of cloud and drizzle properties in the Azores using Doppler Radar spectra

    SciTech Connect

    Luke, E.; Remillard, J.; Kollias, P.

    2010-03-15

    Understanding the onset of coalescence in warm clouds is key in our effort to improve cloud representation in numerical models. Coalescence acts at small scales, and its study requires detailed high-resolution dynamical and microphysical measurements from a comprehensive suite of instruments over a wide range of environmental conditions (e.g., aerosol loading). The first AMF is currently in its second year of a two-year deployment at Graciosa Island in the Azores, offering the opportunity to collect a long data set from a stable land-based platform in a marine stratocumulus regime. In this study, recorded WACR Doppler spectra are used to characterize the properties of Doppler spectra from warm clouds with and without drizzle, and from drizzle only, in an effort to observe the transition (onset) to precipitation in clouds. A retrieval technique that decomposes observed Doppler spectra into their cloud and/or drizzle components is applied in order to quantify drizzle growth.

  12. Microphysical Properties of Warm Clouds During The Aircraft Take-Off and Landing Over Bucharest, Romania

    NASA Astrophysics Data System (ADS)

    Stefan, Sabina; Nicolae Vajaiac, Sorin; Boscornea, Andreea

    2016-06-01

    This paper is focused on airborne measurements of microphysical parameters into warm clouds when the aircraft penetrates the cloud, both during take-off and landing. The experiment was conducted during the aircraft flight between Bucharest and Craiova, in the southern part of Romania. The duration of the experimental flight was 2 hours and 35 minutes in October 7th, 2014, but the present study is dealing solely with the analysis of cloud microphysical properties at the beginning of the experiment (during the aircraft take-off) and at the end, when it got finalized by the aircraft landing procedure. The processing and interpretation of the measurements showed the differences between microphysical parameters, emphasizing that the type of cloud over Bucharest changed, as it was expected. In addition, the results showed that it is important to take into account both the synoptic context and the cloud perturbation due to the velocity of the aircraft, in such cases.

  13. Aerosol Impacts on Cloud Properties Observed during CalWater 2011

    NASA Astrophysics Data System (ADS)

    Suski, K.; Prather, K. A.; Hubbe, J.; Kluzek, C.; Jonsson, H.

    2011-12-01

    In February and March of 2011, an aircraft aerosol time-of-flight mass spectrometer (A-ATOFMS) was deployed on the DOE G-1 during CalWater, a multiyear field campaign aimed at understanding the effects of aerosols and atmospheric rivers on precipitation in California. Flights were conducted out of Sacramento and traversed the western coast of California to the eastern edge of the Sierra Nevada Mountain Range. Initial results show that when heavily processed Asian dust was present, clouds contained more ice than when dust wasn't present, showing that cloud processed Asian dust acts as an efficient ice nucleus. In one particular cloud, salty, processed dust was at the core of most cloud droplets, while aged soot remained unactivated in the interstitial aerosol. These results show that atmospheric aging can have varying effects on CCN and IN abilities. Further analysis of chemical mixing state and atmospheric aging effects on cloud properties are presented.

  14. Radiative properties of cirrus clouds inferred from broadband measurements during FIRE

    NASA Technical Reports Server (NTRS)

    Smith, William L., Jr.; Cox, Stephen K.

    1990-01-01

    It is well known that clouds are significant modulators of weather and climate because of their effects on the radiation field and thus on the energy balance of the earth atmosphere system. As a result, the accurate prediction of weather and climate depends to a significant degree on the accuracy with which cloud radiation interactions can be described. The broadband radiative and microphysical properties of five cirrus cloud systems are reported, as observed from the NCAR Sabreliner during the FIRE first Cirrus IFO, in order to better understand cirrus cloud-radiation interactions. A broadband infrared (BBIR) radiative transfer model is used to deduce BBIR absorption coefficients in order to assess the impact of the cirrus clouds on infrared radiation. The relationships of these absorption coefficients to temperature and microphysical characteristics are explored.

  15. Impact of Cloud Model Microphysics on Passive Microwave Retrievals of Cloud Properties. Part II: Uncertainty in Rain, Hydrometeor Structure, and Latent Heating Retrievals

    NASA Astrophysics Data System (ADS)

    Seo, Eun-Kyoung; Biggerstaff, Michael I.

    2006-07-01

    The impact of model microphysics on the retrieval of cloud properties based on passive microwave observations was examined using a three-dimensional, nonhydrostatic, adaptive-grid cloud model to simulate a mesoscale convective system over ocean. Two microphysical schemes, based on similar bulk two-class liquid and three-class ice parameterizations, were used to simulate storms with differing amounts of supercooled cloud water typical of both the tropical oceanic environment, in which there is little supercooled cloud water, and midlatitude continental environments in which supercooled cloud water is more plentiful. For convective surface-level rain rates, the uncertainty varied between 20% and 60% depending on which combination of passive and active microwave observations was used in the retrieval. The uncertainty in surface rain rate did not depend on the microphysical scheme or the parameter settings except for retrievals over stratiform regions based on 85-GHz brightness temperatures TB alone or 85-GHz TB and radar reflectivity combined. In contrast, systematic differences in the treatment of the production of cloud water, cloud ice, and snow between the parameterization schemes coupled with the low correlation between those properties and the passive microwave TB examined here led to significant differences in the uncertainty in retrievals of those cloud properties and latent heating. The variability in uncertainty of hydrometeor structure and latent heating associated with the different microphysical parameterizations exceeded the inherent variability in TB cloud property relations. This was true at the finescales of the cloud model as well as at scales consistent with satellite footprints in which the inherent variability in TB cloud property relations are reduced by area averaging.

  16. Upper tropospheric cloud systems derived from IR sounders: properties of cirrus anvils in the tropics

    NASA Astrophysics Data System (ADS)

    Protopapadaki, Sofia E.; Stubenrauch, Claudia J.; Feofilov, Artem G.

    2017-03-01

    Representing about 30 % of the Earth's total cloud cover, upper tropospheric clouds play a crucial role in the climate system by modulating the Earth's energy budget and heat transport. When originating from convection, they often form organized systems. The high spectral resolution of the Atmospheric Infrared Sounder (AIRS) allows reliable cirrus identification, both from day and nighttime observations. Tropical upper tropospheric cloud systems have been analyzed by using a spatial composite technique on the retrieved cloud pressure of AIRS data. Cloud emissivity is used to distinguish convective core, cirrus and thin cirrus anvil within these systems. A comparison with simultaneous precipitation data from the Advanced Microwave Scanning Radiometer - Earth Observing System (AMSR-E) shows that, for tropical upper tropospheric clouds, a cloud emissivity close to 1 is strongly linked to a high rain rate, leading to a proxy to identify convective cores. Combining AIRS cloud data with this cloud system approach, using physical variables, provides a new opportunity to relate the properties of the anvils, including also the thinner cirrus, to the convective cores. It also distinguishes convective cloud systems from isolated cirrus systems. Deep convective cloud systems, covering 15 % of the tropics, are further distinguished into single-core and multi-core systems. Though AIRS samples the tropics only twice per day, the evolution of longer-living convective systems can be still statistically captured, and we were able to select relatively mature single-core convective systems by using the fraction of convective core area within the cloud systems as a proxy for maturity. For these systems, we have demonstrated that the physical properties of the anvils are related to convective depth, indicated by the minimum retrieved cloud temperature within the convective core. Our analyses show that the size of the systems does in general increase with convective depth, though for

  17. Retrieving microphysical properties and air motion of cirrus clouds based on the doppler moments method using cloud radar

    NASA Astrophysics Data System (ADS)

    Zhong, Lingzhi; Liu, Liping; Deng, Min; Zhou, Xiuji

    2012-05-01

    Radar parameters including radar reflectivity, Doppler velocity, and Doppler spectrum width were obtained from Doppler spectrum moments. The Doppler spectrum moment is the convolution of both the particle spectrum and the mean air vertical motion. Unlike strong precipitation, the motion of particles in cirrus clouds is quite close to the air motion around them. In this study, a method of Doppler moments was developed and used to retrieve cirrus cloud microphysical properties such as the mean air vertical velocity, mass-weighted diameter, effective particle size, and ice content. Ice content values were retrieved using both the Doppler spectrum method and classic Z-IWC (radar reflectivity-ice water content) relationships; however, the former is a more reasonable method.

  18. Final Technical Report for "Ice nuclei relation to aerosol properties: Data analysis and model parameterization for IN in mixed-phase clouds" (DOE/SC00002354)

    SciTech Connect

    Anthony Prenni; Kreidenweis, Sonia M.

    2012-09-28

    Clouds play an important role in weather and climate. In addition to their key role in the hydrologic cycle, clouds scatter incoming solar radiation and trap infrared radiation from the surface and lower atmosphere. Despite their importance, feedbacks involving clouds remain as one of the largest sources of uncertainty in climate models. To better simulate cloud processes requires better characterization of cloud microphysical processes, which can affect the spatial extent, optical depth and lifetime of clouds. To this end, we developed a new parameterization to be used in numerical models that describes the variation of ice nuclei (IN) number concentrations active to form ice crystals in mixed-phase (water droplets and ice crystals co-existing) cloud conditions as these depend on existing aerosol properties and temperature. The parameterization is based on data collected using the Colorado State University continuous flow diffusion chamber in aircraft and ground-based campaigns over a 14-year period, including data from the DOE-supported Mixed-Phase Arctic Cloud Experiment. The resulting relationship is shown to more accurately represent the variability of ice nuclei distributions in the atmosphere compared to currently used parameterizations based on temperature alone. When implemented in one global climate model, the new parameterization predicted more realistic annually averaged cloud water and ice distributions, and cloud radiative properties, especially for sensitive higher latitude mixed-phase cloud regions. As a test of the new global IN scheme, it was compared to independent data collected during the 2008 DOE-sponsored Indirect and Semi-Direct Aerosol Campaign (ISDAC). Good agreement with this new data set suggests the broad applicability of the new scheme for describing general (non-chemically specific) aerosol influences on IN number concentrations feeding mixed-phase Arctic stratus clouds. Finally, the parameterization was implemented into a regional

  19. The Effect of Asian Dust Aerosols on Cloud Properties and Radiative Forcing from MODIS and CERES

    NASA Technical Reports Server (NTRS)

    Huang, Jianping; Minnis, Patrick; Lin, Bing; Wang, Tianhe; Yi, Yuhong; Hu, Yongxiang; Sun-Mack, Sunny; Ayers, Kirk

    2005-01-01

    The effects of dust storms on cloud properties and radiative forcing are analyzed over northwestern China from April 2001 to June 2004 using data collected by the Moderate Resolution Imaging Spectroradiometer (MODIS) and Clouds and the Earth's Radiant Energy System (CERES) instruments on the Aqua and Terra satellites. On average, ice cloud effective particle diameter, optical depth and ice water path of the cirrus clouds under dust polluted conditions are 11%, 32.8%, and 42% less, respectively, than those derived from ice clouds in dust-free atmospheric environments. The humidity differences are larger in the dusty region than in the dust-free region, and may be caused by removal of moisture by wet dust precipitation. Due to changes in cloud microphysics, the instantaneous net radiative forcing is reduced from -71.2 W/m2 for dust contaminated clouds to -182.7 W/m2 for dust-free clouds. The reduced cooling effects of dusts may lead to a net warming of 1 W/m2, which, if confirmed, would be the strongest aerosol forcing during later winter and early spring dust storm seasons over the studied region.

  20. Near-Cloud Aerosol Properties from the 1 Km Resolution MODIS Ocean Product

    NASA Technical Reports Server (NTRS)

    Varnai, Tamas; Marshak, Alexander

    2014-01-01

    This study examines aerosol properties in the vicinity of clouds by analyzing high-resolution atmospheric correction parameters provided in the MODIS (Moderate Resolution Imaging Spectroradiometer) ocean color product. The study analyzes data from a 2 week long period of September in 10 years, covering a large area in the northeast Atlantic Ocean. The results indicate that on the one hand, the Quality Assessment (QA) flags of the ocean color product successfully eliminate cloud-related uncertainties in ocean parameters such as chlorophyll content, but on the other hand, using the flags introduces a sampling bias in atmospheric products such as aerosol optical thickness (AOT) and Angstrom exponent. Therefore, researchers need to select QA flags by balancing the risks of increased retrieval uncertainties and sampling biases. Using an optimal set of QA flags, the results reveal substantial increases in optical thickness near clouds-on average the increase is 50% for the roughly half of pixels within 5 km from clouds and is accompanied by a roughly matching increase in particle size. Theoretical simulations show that the 50% increase in 550nm AOT changes instantaneous direct aerosol radiative forcing by up to 8W/m2 and that the radiative impact is significantly larger if observed near-cloud changes are attributed to aerosol particles as opposed to undetected cloud particles. These results underline that accounting for near-cloud areas and understanding the causes of near-cloud particle changes are critical for accurate calculations of direct aerosol radiative forcing.

  1. Properties of the electron cloud in a high-energy positron and electron storage ring

    DOE PAGES

    Harkay, K. C.; Rosenberg, R. A.

    2003-03-20

    Low-energy, background electrons are ubiquitous in high-energy particle accelerators. Under certain conditions, interactions between this electron cloud and the high-energy beam can give rise to numerous effects that can seriously degrade the accelerator performance. These effects range from vacuum degradation to collective beam instabilities and emittance blowup. Although electron-cloud effects were first observed two decades ago in a few proton storage rings, they have in recent years been widely observed and intensely studied in positron and proton rings. Electron-cloud diagnostics developed at the Advanced Photon Source enabled for the first time detailed, direct characterization of the electron-cloud properties in amore » positron and electron storage ring. From in situ measurements of the electron flux and energy distribution at the vacuum chamber wall, electron-cloud production mechanisms and details of the beam-cloud interaction can be inferred. A significant longitudinal variation of the electron cloud is also observed, due primarily to geometrical details of the vacuum chamber. Furthermore, such experimental data can be used to provide realistic limits on key input parameters in modeling efforts, leading ultimately to greater confidence in predicting electron-cloud effects in future accelerators.« less

  2. Retrieving ice cloud properties by using a fast infrared radiative transfer model

    NASA Astrophysics Data System (ADS)

    Wang, C.; Yang, P.; Heidinger, A. K.; Platnick, S. E.; Baum, B. A.

    2010-12-01

    A new fast infrared radiative transfer (RT) model based on pre-computed look-up tables (LUTs) including the LUTs for emissivity function and cloud effective temperature is proposed. This model can be applied to the simulation of upward radiance (or brightness temperature) at 8.5, 11.0 and 12.0 μm at the top of the atmosphere (TOA) under cloudy-sky conditions. Optical depths of Atmospheric layers resulting from gaseous absorption are derived from the correlated-K distribution (CKD) method. The cloud reflection and transmission functions are computed from the discrete ordinates radiative transfer model (DISORT). In addition to the LUTs of reflection and transmission functions of cloud in traditional RT models, the LUTs of emissivity and effective temperature are also included to improve the accuracy. Generally speaking, for an atmosphere containing a single ice cloud layer with small optical thickness (i.e., less than 5.0), the brightness temperature differences (BTDs) between the fast model and DISORT results are approximately less than 0.1K, whereas the BTDs are less than 0.02K when the ice cloud optical thickness is larger than 5.0. Moreover, with the fast RT model, cloud optical and microphysical properties of ice clouds are retrieved from MODIS and CALIPSO observations and the MERRA reanalysis data. The present retrievals are compared with the MODIS operational cloud products (MYD06).

  3. Properties of the electron cloud in a high-energy positron and electron storage ring

    SciTech Connect

    Harkay, K. C.; Rosenberg, R. A.

    2003-03-20

    Low-energy, background electrons are ubiquitous in high-energy particle accelerators. Under certain conditions, interactions between this electron cloud and the high-energy beam can give rise to numerous effects that can seriously degrade the accelerator performance. These effects range from vacuum degradation to collective beam instabilities and emittance blowup. Although electron-cloud effects were first observed two decades ago in a few proton storage rings, they have in recent years been widely observed and intensely studied in positron and proton rings. Electron-cloud diagnostics developed at the Advanced Photon Source enabled for the first time detailed, direct characterization of the electron-cloud properties in a positron and electron storage ring. From in situ measurements of the electron flux and energy distribution at the vacuum chamber wall, electron-cloud production mechanisms and details of the beam-cloud interaction can be inferred. A significant longitudinal variation of the electron cloud is also observed, due primarily to geometrical details of the vacuum chamber. Furthermore, such experimental data can be used to provide realistic limits on key input parameters in modeling efforts, leading ultimately to greater confidence in predicting electron-cloud effects in future accelerators.

  4. Investigation of tropical cirrus cloud properties using ground based lidar measurements

    NASA Astrophysics Data System (ADS)

    Dhaman, Reji K.; Satyanarayana, Malladi; Krishnakumar, V.; Mahadevan Pillai, V. P.; Jayeshlal, G. S.; Raghunath, K.; Venkat Ratnam, M.

    2016-05-01

    Cirrus clouds play a significant role in the Earths radiation budget. Therefore, knowledge of geometrical and optical properties of cirrus cloud is essential for the climate modeling. In this paper, the cirrus clouds microphysical and optical properties are made by using a ground based lidar measurements over an inland tropical station Gadanki (13.5°N, 79.2°E), Andhra Pradesh, India. The variation of cirrus microphysical and optical properties with mid cloud temperature is also studied. The cirrus clouds mean height is generally observed in the range of 9-17km with a peak occurrence at 13- 14km. The cirrus mid cloud temperature ranges from -81°C to -46°C. The cirrus geometrical thickness ranges from 0.9- 4.5km. During the cirrus occurrence days sub-visual, thin and dense cirrus were at 37.5%, 50% and 12.5% respectively. The monthly cirrus optical depth ranges from 0.01-0.47, but most (<80%) of the cirrus have values less than 0.1. Optical depth shows a strong dependence with cirrus geometrical thickness and mid-cloud height. The monthly mean cirrus extinction ranges from 2.8E-06 to 8E-05 and depolarization ratio and lidar ratio varies from 0.13 to 0.77 and 2 to 52 sr respectively. A positive correlation exists for both optical depth and extinction with the mid-cloud temperature. The lidar ratio shows a scattered behavior with mid-cloud temperature.

  5. Retrievals of ice cloud microphysical properties of deep convective systems using radar measurements: Convective Cloud Microphysical Retrieval

    SciTech Connect

    Tian, Jingjing; Dong, Xiquan; Xi, Baike; Wang, Jingyu; Homeyer, Cameron R.; McFarquhar, Greg M.; Fan, Jiwen

    2016-09-23

    This study presents new algorithms for retrieving ice cloud microphysical properties (ice water content (IWC) and median mass diameter (Dm)) for the stratiform and thick anvil regions of Deep Convective Systems (DCSs) using Next-Generation Radar (NEXRAD) reflectivity and recently developed empirical relationships from aircraft in situ measurements during the Midlatitude Continental Convective Clouds Experiment (MC3E). A classic DCS case on 20 May 2011 is used to compare the retrieved IWC profiles with other retrieval and cloud-resolving model simulations. The mean values of each retrieved and simulated IWC fall within one standard derivation of the other two. The statistical results from six selected cases during MC3E show that the aircraft in situ derived IWC and Dm are 0.47 ± 0.29 g m-3 and 2.02 ± 1.3 mm, while the mean values of retrievals have a positive bias of 0.16 g m-3 (34%) and a negative bias of 0.39 mm (19%). To validate the newly developed retrieval algorithms from this study, IWC and Dm are performed with other DCS cases during Bow Echo and Mesoscale Convective Vortex Experiment (BAMEX) field campaign using composite gridded NEXRAD reflectivity and compared with in situ IWC and Dm from aircraft. A total of 64 1-min collocated aircraft and radar samples are available for comparisons, and the averages of radar retrieved and aircraft in situ measured IWCs are 1.22 g m-3 and 1.26 g m-3 with a correlation of 0.5, and their averaged Dm values are 2.15 and 1.80 mm. These comparisons have shown that the retrieval algorithms 45 developed during MC3E can retrieve similar ice cloud microphysical properties of DCS to aircraft in situ measurements during BAMEX with median errors of ~40% and ~25% for IWC and Dm retrievals, respectively. This is indicating our retrieval algorithms are suitable for other midlatitude continental DCS ice clouds, especially at stratiform rain and thick anvil regions. In addition, based on the averaged IWC and Dm values during MC3E and

  6. Comparisons of cirrus cloud microphysical properties between polluted and pristine air

    NASA Astrophysics Data System (ADS)

    Diao, Minghui; Schumann, Ulrich; Minikin, Andreas; Jensen, Jorgen

    2015-04-01

    Cirrus clouds occur in the upper troposphere at altitudes where atmospheric radiative forcing is most sensitive to perturbations of water vapor concentration and water phase. The formation of cirrus clouds influences the distributions of water in both vapor and ice forms. The radiative properties of cirrus depend strongly on particle sizes. Currently it is still unclear how the formation of cirrus clouds and their microphysical properties are influenced by anthropogenic emissions (e.g., industrial emission and biomass burning). If anthropogenic emissions influence cirrus formation in a significant manner, then one should expect a systematic difference in cirrus properties between pristine (clean) air and polluted air. Because of the pollution contrasts between the Southern (SH) and Northern Hemispheres (NH), cirrus properties could have hemispheric differences as well. Therefore, we study high-resolution (~200 m), in-situ observations from two global flight campaigns: 1) the HIAPER Pole-to-Pole Observations (HIPPO) global campaign in 2009-2011 funded by the US National Science Foundation (NSF), and 2) the Interhemispheric Differences In Cirrus Properties from Anthropogenic Emissions (INCA) campaign in 2000 funded by the European Union and participating research institutions. To investigate the changes of cirrus clouds by anthropogenic emissions, we compare ice crystal distributions in polluted and pristine air, in terms of their frequency occurrence, number concentration (Nc) and mean diameter (i.e., effective-mean Deff and volume-mean Dc). Total aerosol concentration is used to represent the combined influence of natural and anthropogenic aerosols. In addition, measured carbon monoxide (CO) mixing ratio is used to discriminate between polluted and pristine air masses. All analyses are restricted to temperatures ≤ -40°C to exclude mixed-phased clouds. The HIPPO campaign observations were obtained over the North America continent and the central Pacific Ocean

  7. Factors Affecting the Textural Properties of Pork

    ERIC Educational Resources Information Center

    Holmer, Sean Frederick

    2009-01-01

    Research concerning rate and extent of tenderization has focused on beef or lamb. However, it is critical to understand these processes in pork, especially as retailers move towards minimally processed or non-enhanced product. The objectives of this experiment were to evaluate the textural properties of pork (firmness and tenderness) by examining…

  8. Investigation of cloud properties and atmospheric stability with MODIS

    NASA Technical Reports Server (NTRS)

    Menzel, Paul

    1995-01-01

    In the past six months several milestones were accomplished. The MODIS Airborne Simulator (MAS) was flown in a 50 channel configuration for the first time in January 1995 and the data were calibrated and validated; in the same field campaign the approach for validating MODIS radiances using the MAS and High resolution Interferometer Sounder (HIS) instruments was successfully tested on GOES-8. Cloud masks for two scenes (one winter and the other summer) of AVHRR local area coverage from the Gulf of Mexico to Canada were processed and forwarded to the SDST for MODIS Science Team investigation; a variety of surface and cloud scenes were evident. Beta software preparations continued with incorporation of the EOS SDP Toolkit. SCAR-C data was processed and presented at the biomass burning conference. Preparations for SCAR-B accelerated with generation of a home page for access to real time satellite data related to biomass burning; this will be available to the scientists in Brazil via internet on the World Wide Web. The CO2 cloud algorithm was compared to other algorithms that differ in their construction of clear radiance fields. The HIRS global cloud climatology was completed for six years. The MODIS science team meeting was attended by five of the UW scientists.

  9. Effects of instrument characteristics on cloud properties retrieved from satellite imagery data

    NASA Technical Reports Server (NTRS)

    Baldwin, D. G.; Coakley, J. A., Jr.; Zhang, M. S.

    1986-01-01

    The relationships between sensor resolution and derived cloud properties in satellite remote sensing were studied by comparisons of cloud characteristics determined by spatial coherence analysis of AVHRR and GOES data. The latter data were simulated from 11 microns AVHRR data and were assigned a resolution (8 sq km) half that of the AVHRR. Day and nighttime passes were considered for single-layer maritime cloud systems. Sample radiance vs local standard deviation plots of 1024 points are provided for the same area from AVHRR and GOES-East sensors, demonstrating a qualitative agreement.

  10. Validation of GOES-9 Satellite-Derived Cloud Properties over the Tropical Western Pacific Region

    NASA Technical Reports Server (NTRS)

    Khaiyer, Mandana M.; Nordeen, Michele L.; Doeling, David R.; Chakrapani, Venkatasan; Minnis, Patrick; Smith, William L., Jr.

    2004-01-01

    Real-time processing of hourly GOES-9 images in the ARM TWP region began operationally in October 2003 and is continuing. The ARM sites provide an excellent source for validating this new satellitederived cloud and radiation property dataset. Derived cloud amounts, heights, and broadband shortwave fluxes are compared with similar quantities derived from ground-based instrumentation. The results will provide guidance for estimating uncertainties in the GOES-9 products and to develop improvements in the retrieval methodologies and input.

  11. Retrieve Optically Thick Ice Cloud Microphysical Properties by Using Airborne Dual-Wavelength Radar Measurements

    NASA Technical Reports Server (NTRS)

    Wang, Zhien; Heymsfield, Gerald M.; Li, Lihua; Heymsfield, Andrew J.

    2005-01-01

    An algorithm to retrieve optically thick ice cloud microphysical property profiles is developed by using the GSFC 9.6 GHz ER-2 Doppler Radar (EDOP) and the 94 GHz Cloud Radar System (CRS) measurements aboard the high-altitude ER-2 aircraft. In situ size distribution and total water content data from the CRYSTAL-FACE field campaign are used for the algorithm development. To reduce uncertainty in calculated radar reflectivity factors (Ze) at these wavelengths, coincident radar measurements and size distribution data are used to guide the selection of mass-length relationships and to deal with the density and non-spherical effects of ice crystals on the Ze calculations. The algorithm is able to retrieve microphysical property profiles of optically thick ice clouds, such as, deep convective and anvil clouds, which are very challenging for single frequency radar and lidar. Examples of retrieved microphysical properties for a deep convective clouds are presented, which show that EDOP and CRS measurements provide rich information to study cloud structure and evolution. Good agreement between IWPs derived from an independent submillimeter-wave radiometer, CoSSIR, and dual-wavelength radar measurements indicates accuracy of the IWC retrieved from the two-frequency radar algorithm.

  12. Building a Global Network of Hydro-climatology Sites in Cloud-affected Tropical Montane Forests

    NASA Astrophysics Data System (ADS)

    Moore, G. W.; Asbjornsen, H.; Bruijnzeel, S., Sr.; Berry, Z. C.; Giambelluca, T. W.; Martin, P.; Mulligan, M.

    2015-12-01

    Tropical montane forests are characteristically wet environments with low evapotranspiration and sometimes significant contributions from fog interception. They are often located at headwater catchments critical for water supplies, but ecohydroclimate data in these regions are sparse. Such evidence may be crucial for assessing climate alterations in these sensitive ecosystems. As part of a global effort led by the Tropical Montane Cloud Forest Research Coordination Network (Cloudnet - http://cloudnet.agsci.colostate.edu), we aim to extend the network of tropical montane forest sites and establish robust protocols for measuring key ecohydroclimatic parameters, including fog interception, windblown rain, throughfall, leaf wetness, and micrometeorological conditions. Specific recommendations for standardized protocols include (1) rain and fog collectors uniquely designed to separately quantify fog interception from direct rain inputs, even in windy conditions, (2) trough-style throughfall gages that collect 40 times the area of a typical tipping bucket gage with added features to reduce splash-out, (3) clusters of leaf wetness sensors to differentiate frequency and duration of wetness caused by rain and fog on windward and leeward exposures, and (4) basic micrometeorological sensors for solar radiation, temperature, humidity, and wind. At sites where resources allow for additional measurements, we developed protocols for quantifying soil moisture, soil saturation, and plant water uptake from both roots and leaves (i.e. foliar absorption), since these are also important drivers in these systems. Participating sites will be invited to contribute to a global meta-analysis that will provide new insights into the ecohydrology of cloud-affected tropical montane forests.

  13. City snow's physicochemical property affects snow disposal

    NASA Astrophysics Data System (ADS)

    Dovbysh, V. O.; Sharukha, A. V.; Evtin, P. V.; Vershinina, S. V.

    2015-10-01

    At the present day the industrial cities run into severe problem: fallen snow in a city it's a concentrator of pollutants and their quantity is constantly increasing by technology development. Pollution of snow increases because of emission of gases to the atmosphere by cars and factories. Large accumulation of polluted snow engenders many vexed ecological problems. That's why we need a new, non-polluting, scientifically based method of snow disposal. This paper investigates polluted snow's physicochemical property effects on snow melting. A distinctive feature of the ion accelerators with self-magnetically insulated diode is that there.

  14. A Midlatitude Cirrus Cloud Climatology from the Facility for Atmospheric Remote Sensing. Part III: Radiative Properties

    SciTech Connect

    Sassen, K.; Comstock, Jennifer M.

    2001-08-01

    In Part III of a series of papers describing the extended time high-cloud observations from the University of Utah Facility for Atmospheric Remote Sensing (FARS) supporting the First International Satellite Cloud Climatology Project (ISCCP) Regional Experiment, the visible and infrared radiative properties of cirrus clouds over Salt Lake City, Utah, are examined. Using {approx}860 h of combined ruby (0.694 {micro}m) lidar and midinfrared (9.5-11.5 {micro}m) radiometer data collected between 1992 and 1999 from visually identified cirrus clouds, the visible optical depths {tau} and infrared layer emittance epsilon of the varieties of midlatitude cirrus are characterized. The mean and median values for the cirrus sample are 0.75 {+-} 0.91 and 0.61 for {tau}, and 0.30 {+-} 0.22 and 0.25 for epsilon. Other scattering parameters studied are the visible extinction and infrared absorption coefficients, and their ratio, and the lidar backscatter-to-extinction ratio, which has a mean value of 0.041 sr{sup -1}. Differences among cirrus clouds generated by general synoptic (e.g., jet stream), thunderstorm anvil, and orographic mechanisms are found, reflecting basic cloud microphysical effects. The authors draw parameterizations in terms of midcloud temperature T{sub m} and physical cloud thickness {Delta}z for epsilon and {tau}: both macrophysical variables are needed to adequately address the impact of the adiabatic process on ice cloud content, which modulates radiative transfer as a function of temperature. For the total cirrus dataset, the authors find epsilon = 1 -exp [-8.5 x 10{sup -5} (T{sub m} + 80 C) {Delta}z]. These parameterizations, based on a uniquely comprehensive dataset, hold the potential for improving weather and climate model predictions, and satellite cloud property retrieval methods.

  15. MILKY WAY DISK-HALO TRANSITION IN H I: PROPERTIES OF THE CLOUD POPULATION

    SciTech Connect

    Ford, H. Alyson; Lockman, Felix J.; McClure-Griffiths, N. M.

    2010-10-10

    Using 21 cm H I observations from the Parkes Radio Telescope's Galactic All-Sky Survey, we measure 255 H I clouds in the lower Galactic halo that are located near the tangent points at 16.{sup 0}9 {<=} l {<=} 35.{sup 0}3 and |b| {approx}< 20{sup 0}. The clouds have a median mass of 700 M{sub sun} and a median distance from the Galactic plane of 660 pc. This first Galactic quadrant (QI) region is symmetric to a region of the fourth quadrant (QIV) studied previously using the same data set and measurement criteria. The properties of the individual clouds in the two quadrants are quite similar suggesting that they belong to the same population, and both populations have a line-of-sight (LOS) cloud-cloud velocity dispersion of {sigma}{sub cc} {approx} 16 km s{sup -1}. However, there are three times as many disk-halo clouds at the QI tangent points and their scale height, at h = 800 pc, is twice as large as in QIV. Thus, the observed LOS random cloud motions are not connected to the cloud scale height or its variation around the Galaxy. The surface density of clouds is nearly constant over the QI tangent point region but is peaked near R {approx} 4 kpc in QIV. We ascribe all of these differences to the coincidental location of the QI region at the tip of the Milky Way's bar, where it merges with a major spiral arm. The QIV tangent point region, in contrast, covers only a segment of a minor spiral arm. The disk-halo H I cloud population is thus likely tied to and driven by large-scale star formation processes, possibly through the mechanism of supershells and feedback.

  16. Some Peculiar Properties of Magnetic Clouds as Observed by the WIND Spacecraft

    NASA Technical Reports Server (NTRS)

    Berdichevsky, D.; Lepping, R. P.; Szabo, A.; Burlaga, L. F.; Thompson, B. J.; Lazarus, A. J.; Steinburg, J. T.; Mariani, F.

    1999-01-01

    We aimed at understanding the common characteristics of magnetic clouds, relevant to solar-interplanetary connections, but exceptional ones were noted and are stressed here through a short compendium. The study is based on analyses of 28 good or better events (Out of 33 candidates) as identified in WIND magnetic field and plasma data. These cloud intervals are provided by WIND-MFI's Website under the URL (http://lepmfi.gsfc.nasa.gov/mfi/mag_cloud_publ.html#table). The period covered is from early 1995 to November 1998. A force free, cylindrically symmetric, magnetic field model has been applied to the field data in usually 1-hour averaged form for the cloud analyses. Some of the findings are: (1) one small duration event turned out to have an approximately normal size which was due to a distant almost "skimming" passage by the spacecraft; (2) One truly small event was observed, where 10 min averages had to be used in the model fitting; it had an excellent model fit and the usual properties of a magnetic cloud, except it possessed a small axial magnetic flux; (3) One cloud ha a dual axial-field-polarity, in the sense that the "core" had one polarity and the annular region around it had an opposite polarity. This event also satisfied the model and with a ve3ry good chi-squared value. Some others show a hint of this dual polarity; (4) The temporal distribution of occurrence clouds over the 4 years show a dip in 1996; (5) About 50 % of the clouds had upstream shocks; any others had upstream pressure pulses; (6) The overall average speed (390 km/s) of the best 28 events is less than the normally quoted for the average solar wind speed (420 km/s) The average of central cloud speed to the upstream solar wind speed was not much greater than one (1.08), even though many of these clouds were drivers of interplanetary shocks. Cloud expansion is partly the reason for the existence of upstream shocks; (7) The cloud axes often (about 50 % of the time) revealed reasonable

  17. A Comparison Of Cloud Microphysical Properties Derived Using VIRS 3.7 Micron and 1.6 Micron Data

    NASA Technical Reports Server (NTRS)

    Young, David F.; Minnis, Patrick; Arduini, Robert F.

    1999-01-01

    One of the main objectives of the Clouds and the Earth's Radiant Energy System (CERES) project is the retrieval of cloud physical and microphysical properties simultaneously with observations of broadband radiative fluxes. These cloud parameter sare used for three main purposes: 1) to provide data for radiation-cloud climate feedback studies; 2) to provide scene identification data for the construction and application of angular distribution models; and 3) to be used as input to radiative transfer calculations of intra-atmospheric fluxes

  18. Cloud and Precipitation Properties Merged Dataset from Vertically Pointing ARM Radars During GOAmazon

    NASA Astrophysics Data System (ADS)

    Toto, T.; Giangrande, S. E.; Troyan, D.; Jensen, M. P.; Bartholomew, M. J.; Johnson, K. L.

    2014-12-01

    The Green Ocean Amazon (GOAmazon) field campaign is in its first year of a two-year deployment in the Amazon Basin to study aerosol and cloud lifecycles as they relate to cloud-aerosol-precipitation interactions. Insights from GOAmazon datasets will fill gaps in our understanding, ultimately improving constraints in tropical rain forest climate model parameterizations. As part of GOAmazon, the Atmospheric Radiation Measurement (ARM) Mobile Facility (AMF) has been collecting a unique set of observations near Manacapuru, Brazil, a site known to experience both the pristine condition of its locale as well as, at times, the effects of the Manaus, Brazil, mega city pollution plume. In order to understand the effects of anthropogenic aerosol on clouds, radiative balance and climate, documentation of cloud and precipitation properties in the absence and presence of the Manaus plume is a necessary complement to the aerosol measurements collected during the campaign. The AMF is uniquely equipped to capture the most complete and continuous record of cloud and precipitation column properties using the UHF (915 MHz) ARM zenith radar (UAZR) and vertically pointing W-Band (95 GHz) ARM Cloud Radar (WACR). Together, these radars provide multiple methods (e.g., moment-based, dual-frequency, and Doppler spectral techniques) to retrieve properties of the cloud field that may be influenced by aerosols. This includes drop size distribution, dynamical and microphysical properties (e.g., vertical air motion, latent heat retrievals), and associated uncertainties. Additional quality assurance is available from independent rain gauge and column platforms. Here, we merge data from the UAZR and WACR (WACR-ARSCL VAP) radars, along with ARM Sounding observations and optical parsivel measurement constraints, to present a first look at select convective and stratiform events, their precipitation properties and statistical profile characterization.

  19. Population properties affect inbreeding avoidance in moose.

    PubMed

    Herfindal, Ivar; Haanes, Hallvard; Røed, Knut H; Solberg, Erling J; Markussen, Stine S; Heim, Morten; Sæther, Bernt-Erik

    2014-12-01

    Mechanisms reducing inbreeding are thought to have evolved owing to fitness costs of breeding with close relatives. In small and isolated populations, or populations with skewed age- or sex distributions, mate choice becomes limited, and inbreeding avoidance mechanisms ineffective. We used a unique individual-based dataset on moose from a small island in Norway to assess whether inbreeding avoidance was related to population structure and size, expecting inbreeding avoidance to be greater in years with larger populations and even adult sex ratios. The probability that a potential mating event was realized was negatively related to the inbreeding coefficient of the potential offspring, with a stronger relationship in years with a higher proportion or number of males in the population. Thus, adult sex ratio and population size affect the degree of inbreeding avoidance. Consequently, conservation managers should aim for sex ratios that facilitate inbreeding avoidance, especially in small and isolated populations.

  20. Near-cloud aerosol properties from the 1 km resolution MODIS ocean product

    NASA Astrophysics Data System (ADS)

    Várnai, Tamás.; Marshak, Alexander

    2014-02-01

    This study examines aerosol properties in the vicinity of clouds by analyzing high-resolution atmospheric correction parameters provided in the MODIS (Moderate Resolution Imaging Spectroradiometer) ocean color product. The study analyzes data from a 2 week long period of September in 10 years, covering a large area in the northeast Atlantic Ocean. The results indicate that on the one hand, the Quality Assessment (QA) flags of the ocean color product successfully eliminate cloud-related uncertainties in ocean parameters such as chlorophyll content, but on the other hand, using the flags introduces a sampling bias in atmospheric products such as aerosol optical thickness (AOT) and Angstrom exponent. Therefore, researchers need to select QA flags by balancing the risks of increased retrieval uncertainties and sampling biases. Using an optimal set of QA flags, the results reveal substantial increases in optical thickness near clouds—on average the increase is 50% for the roughly half of pixels within 5 km from clouds and is accompanied by a roughly matching increase in particle size. Theoretical simulations show that the 50% increase in 550 nm AOT changes instantaneous direct aerosol radiative forcing by up to 8 W/m2 and that the radiative impact is significantly larger if observed near-cloud changes are attributed to aerosol particles as opposed to undetected cloud particles. These results underline that accounting for near-cloud areas and understanding the causes of near-cloud particle changes are critical for accurate calculations of direct aerosol radiative forcing.

  1. Natural versus anthropogenic factors affecting low-level cloud albedo over the North Atlantic

    NASA Technical Reports Server (NTRS)

    Falkowski, Paul G.; Kim, Yongseung; Kolber, Zbigniew; Wilson, Cara; Wirick, Creighton; Cess, Robert

    1992-01-01

    Cloud albedo plays a key role in regulating earth's climate. Cloud albedo depends on column-integrated liquid water content and the density of cloud condensation nuclei, which consists primarily of submicrometer-sized aerosol sulfate particles. A comparison of two independent satellite data sets suggests that, although anthropogenic sulfate emissions may enhance cloud albedo immediately adjacent to the east coast of the United States, over the central North Atlantic Ocean the variability in albedo can be largely accounted for by natural marine and atmospheric processes that probably have remained relatively constant since the beginning of the industrial revolution.

  2. Sensitivity of simulated snow cloud properties to mass-diameter parameterizations.

    NASA Astrophysics Data System (ADS)

    Duffy, G.; Nesbitt, S. W.; McFarquhar, G. M.

    2015-12-01

    Mass to diameter (m-D) relationships are used in model parameterization schemes to represent ice cloud microphysics and in retrievals of bulk cloud properties from remote sensing instruments. One of the most common relationships, used in the current Global Precipitation Measurement retrieval algorithm for example, assigns the density of snow as a constant tenth of the density of ice (0.1g/m^3). This assumption stands in contrast to the results of derived m-D relationships of snow particles, which imply decreasing particle densities at larger sizes and result in particle masses orders of magnitude below the constant density relationship. In this study, forward simulations of bulk cloud properties (e.g., total water content, radar reflectivity and precipitation rate) derived from measured size distributions using several historical m-D relationships are presented. This expands upon previous studies that mainly focused on smaller ice particles because of the examination of precipitation-sized particles here. In situ and remote sensing data from the GPM Cold season Experiment (GCPEx) and Canadian CloudSAT/Calypso Validation Program (C3VP), both synoptic snowstorm field experiments in southern Ontario, Canada, are used to evaluate the forward simulations against total water content measured by the Nevzorov and Cloud Spectrometer and Impactor (CSI) probe, radar reflectivity measured by a C band ground based radar and a nadir pointing Ku/Ka dual frequency airborne radar, and precipitation rate measured by a 2D video disdrometer. There are differences between the bulk cloud properties derived using varying m-D relations, with constant density assumptions producing results differing substantially from the bulk measured quantities. The variability in bulk cloud properties derived using different m-D relations is compared against the natural variability in those parameters seen in the GCPEx and C3VP field experiments.

  3. Active Imaging through Cirrus Clouds.

    PubMed

    Landesman, B; Kindilien, P; Pierson, R; Matson, C; Mosley, D

    1997-11-24

    The presence of clouds of ice particles in the uplink and downlink path of an illumination beam can severely impede the performance of an active imaging system. Depending on the optical depth of the cloud, i.e., its density and depth, the beam can be completely scattered and extinguished, or the beam can pass through the cloud with some fraction attenuated, scattered, and depolarized. In particular, subvisual cirrus clouds, i.e., high, thin cirrus clouds that cannot be observed from the ground, can affect the properties and alignment of both uplink and downlink beams. This paper discusses the potential for active imaging in the presence of cirrus clouds. We document field data results from an active imaging experiment conducted several years ago, which the authors believe to show the effects of cirrus clouds on an active imaging system. To verify these conclusions, we include the results of a simulation of the interaction of a coherent illumination scheme with a cirrus cloud.

  4. The Microbase Value-Added Product: A Baseline Retrieval of Cloud Microphysical Properties

    SciTech Connect

    Dunn, M; Johnson, K; Jensen, M

    2011-05-31

    This report describes the Atmospheric Radiation Measurement (ARM) Climate Research Facility baseline cloud microphysical properties (MICROBASE) value-added product (VAP). MICROBASE uses a combination of millimeter-wavelength cloud radar, microwave radiometer, and radiosonde observations to estimate the vertical profiles of the primary microphysical parameters of clouds including the liquid/ice water content and liquid/ice cloud particle effective radius. MICROBASE is a baseline algorithm designed to apply to most conditions and locations using a single set of parameterizations and a simple determination of water phase based on temperature. This document provides the user of this product with guidelines to assist in determining the accuracy of the product under certain conditions. Quality control flags are designed to identify outliers and indicate instances where the retrieval assumptions may not be met. The overall methodology is described in this report through a detailed description of the input variables, algorithms, and output products.

  5. The Influence of Sea Ice on Arctic Low Cloud Properties and Radiative Effects

    NASA Technical Reports Server (NTRS)

    Taylor, Patrick C.

    2015-01-01

    The Arctic is one of the most climatically sensitive regions of the Earth. Climate models robustly project the Arctic to warm 2-3 times faster than the global mean surface temperature, termed polar warming amplification (PWA), but also display the widest range of surface temperature projections in this region. The response of the Arctic to increased CO2 modulates the response in tropical and extra-tropical regions through teleconnections in the atmospheric circulation. An increased frequency of extreme precipitation events in the northern mid-latitudes, for example, has been linked to the change in the background equator-to-pole temperature gradient implied by PWA. Understanding the Arctic climate system is therefore important for predicting global climate change. The ice albedo feedback is the primary mechanism driving PWA, however cloud and dynamical feedbacks significantly contribute. These feedback mechanisms, however, do not operate independently. How do clouds respond to variations in sea ice? This critical question is addressed by combining sea ice, cloud, and radiation observations from satellites, including CERES, CloudSAT, CALIPSO, MODIS, and microwave radiometers, to investigate sea ice-cloud interactions at the interannual timescale in the Arctic. Cloud characteristics are strongly tied to the atmospheric dynamic and thermodynamic state. Therefore, the sensitivity of Arctic cloud characteristics, vertical distribution and optical properties, to sea ice anomalies is computed within atmospheric dynamic and thermodynamic regimes. Results indicate that the cloud response to changes in sea ice concentration differs significantly between atmospheric state regimes. This suggests that (1) the atmospheric dynamic and thermodynamic characteristics and (2) the characteristics of the marginal ice zone are important for determining the seasonal forcing by cloud on sea ice variability.

  6. The properties and fate of the galactic center G2 cloud

    SciTech Connect

    Shcherbakov, Roman V.

    2014-03-01

    The object G2 was recently discovered descending into the gravitational potential of the supermassive black hole (BH) Sgr A*. We test the photoionized cloud scenario, determine the cloud properties, and estimate the emission during the pericenter passage. The incident radiation is computed starting from the individual stars at the locations of G2. The radiative transfer calculations are conducted with CLOUDY code and 2011 broadband and line luminosities are fitted. The spherically symmetric, tidally distorted, and magnetically arrested cloud shapes are tested with both the interstellar medium dust and 10 nm graphite dust. The best-fitting magnetically arrested model has the initial density n {sub init} = 1.8 × 10{sup 5} cm{sup –3}, initial radius R {sub init} = 2.2 × 10{sup 15} cm = 17 mas, mass m {sub cloud} = 4 M {sub Earth}, and dust relative abundance A = 0.072. It provides a good fit to 2011 data, is consistent with the luminosities in 2004 and 2008, and reaches an agreement with the observed size. We revise down the predicted radio and X-ray bow shock luminosities to be below the quiescent level of Sgr A*, which readily leads to non-detection in agreement to observations. The magnetic energy dissipation in the cloud at the pericenter coupled with more powerful irradiation may lead to an infrared source with an apparent magnitude m{sub L{sup ′}}≈13.0. No shock into the cloud and no X-rays are expected from cloud squeezing by the ambient gas pressure. Larger than previously estimated cloud mass m {sub cloud} = (4-20) M {sub Earth} may produce a higher accretion rate and a brighter state of Sgr A* as the debris descend onto the BH.

  7. Retrieval of Polar Stratospheric Cloud Microphysical Properties from Lidar Measurements: Dependence on Particle Shape Assumptions

    NASA Technical Reports Server (NTRS)

    Reichardt, J.; Reichardt, S.; Yang, P.; McGee, T. J.; Bhartia, P. K. (Technical Monitor)

    2001-01-01

    A retrieval algorithm has been developed for the microphysical analysis of polar stratospheric cloud (PSC) optical data obtained using lidar instrumentation. The parameterization scheme of the PSC microphysical properties allows for coexistence of up to three different particle types with size-dependent shapes. The finite difference time domain (FDTD) method has been used to calculate optical properties of particles with maximum dimensions equal to or less than 2 mu m and with shapes that can be considered more representative of PSCs on the scale of individual crystals than the commonly assumed spheroids. Specifically. these are irregular and hexagonal crystals. Selection of the optical parameters that are input to the inversion algorithm is based on a potential data set such as that gathered by two of the lidars on board the NASA DC-8 during the Stratospheric Aerosol and Gas Experiment 0 p (SAGE) Ozone Loss Validation experiment (SOLVE) campaign in winter 1999/2000: the Airborne Raman Ozone and Temperature Lidar (AROTEL) and the NASA Langley Differential Absorption Lidar (DIAL). The 0 microphysical retrieval algorithm has been applied to study how particle shape assumptions affect the inversion of lidar data measured in leewave PSCs. The model simulations show that under the assumption of spheroidal particle shapes, PSC surface and volume density are systematically smaller than the FDTD-based values by, respectively, approximately 10-30% and approximately 5-23%.

  8. Impact of Long-Range Transported African Dust Events on Cloud Composition and Physical Properties at a Caribbean Tropical Montane Cloud Forest

    NASA Astrophysics Data System (ADS)

    Valle-Diaz, C. J.; Torres-Delgado, E.; Lee, T.; Collett, J. L.; Cuadra-Rodriguez, L. A.; Prather, K. A.; Spiegel, J.; Eugster, W.

    2012-12-01

    We studied the impact of long-range transported African Dust (LRTAD) on cloud composition and properties at the Caribbean tropical montane cloud forest (TMCF) of Pico del Este (PE), as part of the Puerto Rico African Dust and Clouds Study (PRADACS). Here we present results from measurements performed in July 2011. Bulk chemical analysis of cloud water and rainwater showed pH and conductivity higher in the presence of dust. pH and conductivity were also higher for larger cloud droplets (size cut of 17 μm at 50% efficiency) suggesting a higher content of dust in this fraction. The concentration of the water-soluble ions in rainwater was found to be lower than for cloud water. This in turn translates to higher pH and lower conductivity. African dust influence at PE was confirmed by the presence of nss-Ca, Fe, Mg, Na, and Al in cloud/rain water, and inferred by HYSPLIT trajectories and the satellite images from the Saharan Air Layer (SAL). Interstitial single-particle size and chemistry measured using aerosol time-of-flight mass spectrometry revealed mostly sea-salt particles (Na, Cl, Ca) and dust particles (Fe, Ti, Mg, nss-Ca). Anthropogenic influence detected as the presence of EC, a tracer for combustion processes, was found to be fairly small according to ATOFMS measurements. An increase of total organic carbon, total nitrogen, and dissolved organic carbon was observed during LRTAD events. Cloud droplet distributions revealed that LRTAD can lead to more numerous, but smaller cloud droplets (around 8 μm in average) at PE. However, total liquid water content appeared to be unaffected by this shift of droplet sizes. Overall, differences in the studied physicochemical properties of aerosols and clouds during dust and non-dust events were observed. Our results show that during LRTAD events, aerosol-cloud-precipitation interactions are altered at PE. Detailed results will be presented at the meeting.

  9. Investigation of Cloud Properties and Atmospheric Profiles with Modis

    NASA Technical Reports Server (NTRS)

    Menzel, Paul; Ackerman, Steve; Moeller, Chris; Gumley, Liam; Strabala, Kathy; Frey, Richard; Prins, Elaine; Laporte, Dan; Wolf, Walter

    1997-01-01

    A major milestone was accomplished with the delivery of all five University of Wisconsin MODIS Level 2 science production software packages to the Science Data Support Team (SDST) for integration. These deliveries were the culmination of months of design and testing, with most of the work focused on tasks peripheral to the actual science contained in the code. LTW hosted a MODIS infrared calibration workshop in September. Considerable progress has been made by MCST, with help from LTW, in refining the calibration algorithm, and in identifying and characterization outstanding problems. Work continues on characterizing the effects of non-blackbody earth surfaces on atmospheric profile retrievals and modeling radiative transfer through cirrus clouds.

  10. Can the removal of molecular cloud envelopes by external feedback affect the efficiency of star formation?

    NASA Astrophysics Data System (ADS)

    Lucas, William E.; Bonnell, Ian A.; Forgan, Duncan H.

    2017-01-01

    We investigate how star formation efficiency can be significantly decreased by the removal of a molecular cloud's envelope by feedback from an external source. Feedback from star formation has difficulties halting the process in dense gas but can easily remove the less dense and warmer envelopes where star formation does not occur. However, the envelopes can play an important role keeping their host clouds bound by deepening the gravitational potential and providing a constraining pressure boundary. We use numerical simulations to show that removal of the cloud envelopes results in all cases in a fall in the star formation efficiency (SFE). At 1.38 free-fall times our 4 pc cloud simulation experienced a drop in the SFE from 16 to six percent, while our 5 pc cloud fell from 27 to 16 per cent. At the same time, our 3 pc cloud (the least bound) fell from an SFE of 5.67 per cent to zero when the envelope was lost. The star formation efficiency per free-fall time varied from zero to ≈0.25 according to α, defined to be the ratio of the kinetic plus thermal to gravitational energy, and irrespective of the absolute star forming mass available. Furthermore the fall in SFE associated with the loss of the envelope is found to even occur at later times. We conclude that the SFE will always fall should a star forming cloud lose its envelope due to stellar feedback, with less bound clouds suffering the greatest decrease.

  11. Cirrus cloud properties derived from coincident GOES and lidar data during the 1986 FIRE Cirrus Intensive Field Observations (IFO)

    NASA Technical Reports Server (NTRS)

    Minnis, Patrick; Alvarez, Jose M.; Young, David F.; Heck, Patrick W.; Sassen, Kenneth

    1990-01-01

    One of the main difficulties in detecting cirrus clouds and determining their correct altitude using satellite measurements is their nonblackness. In the present algorithm (Rossow et al., 1985) used by the International Satellite Cloud Climatology Project (ISCCP), the cirrus cloud emissivity is estimated from the derived cloud reflectance using a theoretical model relating visible (VIS, 0.65 micron) optical depth to infrared (IR, 10.5 micron) emissivity. At this time, it is unknown how accurate this approach is or how the derived cloud altitude relates to the physical properties of the cloud. The First ISCCP Regional Experiment (FIRE) presents opportunities for determining how the observed radiances depend on the cloud properties. During the FIRE Cirrus Intensive Field Observations (IFO, see Starr, 1987), time series of cloud thickness, height, and relative optical densities were measured from several surface-based lidars. Cloud microphysics and radiances at various wavelengths were also measured simultaneously over these sites from aircraft at specific times during the IFO (October 19 to November 2, 1986). Satellite-observed radiances taken simultaneously can be matched with these data to determine their relationships to the cirrus characteristics. The first step is taken toward relating all of these variables to the satellite observations. Lidar-derived cloud heights are used to determine cloud temperatures which are used to estimate cloud emissivities from the satellite IR radiances. These results are then correlated to the observed VIS reflectances for various solar zenith angles.

  12. The ability of a protostellar disc to fragment and the properties of molecular cloud cores

    NASA Astrophysics Data System (ADS)

    Liu, Chunjian; Li, Min; Yao, Zhen; Mao, Xiaodong

    2017-01-01

    We explore the ability of a protostellar disc to fragment using an evolutionary disc model. Our disc model includes the mass influx from a molecular cloud core, the irradiation from the central star, the magnetorotational instability (MRI), and the gravitational instability (Kratter et al. in Astrophys. J. 681:375, 2008). We use the fragmentation criterion of Gammie (Astrophys. J. 553:174, 2001) and Rafikov (Astrophys. J. 621:L69, 2005) to judge whether or not a protostellar disc can fragment. We find that there is a link between whether a protostellar disc can fragment and the properties of the molecular cloud cores (angular velocity ω, temperature T_{core}, and mass M_{core}). In the parameter space ω-M_{core}, there is a critical value ω_{crit}, which divides the parameter space into two regions: one is the fragmentation region, the other is the non-fragmentation region. The protostellar disc can only fragment when ω> ω_{crit}. The reason can be understood as follows. The protostellar disc is formed from the gravitational collapse of a molecular cloud core, the properties of the molecular cloud core determine the properties of the protostellar disc. Thus the two categories of protostellar discs correspond to two categories of molecular cloud cores. Moreover, we find that ω_{crit} is approximately a linear function of M_{core} in log-scale coordinates.

  13. Using CO line ratios to trace the physical properties of molecular clouds

    NASA Astrophysics Data System (ADS)

    Peñaloza, Camilo H.; Clark, Paul C.; Glover, Simon C. O.; Shetty, Rahul; Klessen, Ralf S.

    2017-02-01

    The carbon monoxide (CO) rotational transition lines are the most common tracers of molecular gas within giant molecular clouds (MCs). We study the ratio (R2-1/1-0) between CO's first two emission lines and examine what information it provides about the physical properties of the cloud. To study R2-1/1-0, we perform smooth particle hydrodynamic simulations with time-dependent chemistry (using GADGET-2), along with post-process radiative transfer calculations on an adaptive grid (using RADMC-3D) to create synthetic emission maps of a MC. R2-1/1-0 has a bimodal distribution that is a consequence of the excitation properties of each line, given that J = 1 reaches local thermal equilibrium while J = 2 is still sub-thermally excited in the considered clouds. The bimodality of R2-1/1-0 serves as a tracer of the physical properties of different regions of the cloud, and it helps constrain local temperatures, densities and opacities. Additionally, this bimodal structure shows an important portion of the CO emission comes from diffuse regions of the cloud, suggesting that the commonly used conversion factor of R2-1/1-0 ∼ 0.7 between both lines may need to be studied further.

  14. Diversity on subtropical and polar cirrus clouds properties as derived from both ground-based lidars and CALIPSO/CALIOP measurements

    NASA Astrophysics Data System (ADS)

    Córdoba-Jabonero, Carmen; Lopes, Fabio J. S.; Landulfo, Eduardo; Cuevas, Emilio; Ochoa, Héctor; Gil-Ojeda, Manuel

    2017-01-01

    Cirrus (Ci) cloud properties can change significantly from place to place over the globe as a result of weather processes, reflecting their likely different radiative and climate implications. In this work Cirrus clouds (Ci) features observed in late autumn/early winter season at both subtropical and polar latitudes are examined and compared to CALIPSO/CALIOP observations. Lidar measurements were carried out in three stations: São Paulo (MSP, Brazil) and Tenerife (SCO, Canary Islands, Spain), as subtropical sites, and the polar Belgrano II base (BEL, Argentina) in the Antarctic continent. The backscattering ratio (BSR) profiles and the top and base heights of the Ci layers together to their Cirrus Cloud Optical Depth (CCOD) and Lidar Ratio (LR) for Ci clouds were derived. In addition, temperatures at the top and base boundaries of the Ci clouds were also obtained from local radiosoundings to verify pure ice Ci clouds occurrence using a given temperature top threshold (<- 38 °C). Ci clouds observed along the day were assembled in groups based on their predominant CCOD, and classified according to four CCOD-based categories. Ci clouds were found to be vertically-distributed in relation with the temperature, forming subvisual Ci clouds at lower temperatures and higher altitudes than other Ci categories at both latitudes. Discrepancies shown on LR values for the three stations, but mainly remarked between subtropical and polar cases, can be associated to different temperature regimes for Ci formation, influencing the internal ice habits of the Ci clouds, and hence likely affecting the LR derived for the Ci layer. In comparison with literature values, daily mean CCOD/LR for SCO (0.4 ± 0.4/21 ± 10 sr), MSP (0.5 ± 0.5/27 ± 5 sr) and BEL (0.2 ± 0.3/28 ± 9 sr) are in good agreement; however, the variability of the Ci optical features along the day present large discrepancies. In comparison with CALIOP data, Ci clouds are observed at similar altitudes (around 10

  15. The origin of midlatitude ice clouds and the resulting influence on their microphysical properties

    NASA Astrophysics Data System (ADS)

    Luebke, Anna E.; Afchine, Armin; Costa, Anja; Grooß, Jens-Uwe; Meyer, Jessica; Rolf, Christian; Spelten, Nicole; Avallone, Linnea M.; Baumgardner, Darrel; Krämer, Martina

    2016-05-01

    The radiative role of ice clouds in the atmosphere is known to be important, but uncertainties remain concerning the magnitude and net effects. However, through measurements of the microphysical properties of cirrus clouds, we can better characterize them, which can ultimately allow for their radiative properties to be more accurately ascertained. Recently, two types of cirrus clouds differing by formation mechanism and microphysical properties have been classified - in situ and liquid origin cirrus. In this study, we present observational evidence to show that two distinct types of cirrus do exist. Airborne, in situ measurements of cloud ice water content (IWC), ice crystal concentration (Nice), and ice crystal size from the 2014 ML-CIRRUS campaign provide cloud samples that have been divided according to their origin type. The key features that set liquid origin cirrus apart from the in situ origin cirrus are higher frequencies of high IWC ( > 100 ppmv), higher Nice values, and larger ice crystals. A vertical distribution of Nice shows that the in situ origin cirrus clouds exhibit a median value of around 0.1 cm-3, while the liquid origin concentrations are slightly, but notably higher. The median sizes of the crystals contributing the most mass are less than 200 µm for in situ origin cirrus, with some of the largest crystals reaching 550 µm in size. The liquid origin cirrus, on the other hand, were observed to have median diameters greater than 200 µm, and crystals that were up to 750 µm. An examination of these characteristics in relation to each other and their relationship to temperature provides strong evidence that these differences arise from the dynamics and conditions in which the ice crystals formed. Additionally, the existence of these two groups in cirrus cloud populations may explain why a bimodal distribution in the IWC-temperature relationship has been observed. We hypothesize that the low IWC mode is the result of in situ origin cirrus and the

  16. Comparison of CERES-MODIS cloud microphysical properties with surface observations over Loess Plateau

    NASA Astrophysics Data System (ADS)

    Yan, Hongru; Huang, Jianping; Minnis, Patrick; Yi, Yuhong; Sun-Mack, Sunny; Wang, Tianhe; Nakajima, Takashi Y.

    2015-03-01

    To enhance the utility of satellite-derived cloud properties for studying the role of clouds in climate change and the hydrological cycle in semi-arid areas, it is necessary to know their uncertainties. This paper estimates the uncertainties of several cloud properties by comparing those derived over the China Loess Plateau from the MODerate-resolution Imaging Spectroradiometer (MODIS) on Terra and Aqua by the Clouds and Earth's Radiant Energy System (CERES) with surface observations at the Semi-Arid Climate and Environment Observatory of Lanzhou University (SACOL). The comparisons use data from January 2008 to June 2010 limited to single layer and overcast stratus conditions during daytime. Cloud optical depths (τ) and liquid water paths (LWP) from both Terra and Aqua generally track the variation of the surface counterparts with modest correlation, while cloud effective radius (re) is only weakly correlated with the surface retrievals. The mean differences between Terra and the SACOL retrievals are -4.7±12.9, 2.1±3.2 μm and 30.2±85.3 g m-2 for τ, re and LWP, respectively. The corresponding differences for Aqua are 2.1±8.4, 1.2±2.9 μm and 47.4±79.6 g m-2, respectively. Possible causes for biases of satellite retrievals are discussed through statistical analysis and case studies. Generally, the CERES-MODIS cloud properties have a bit larger biases over the Loess Plateau than those in previous studies over other locations.

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

    NASA Astrophysics Data System (ADS)

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

    2009-11-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2009-07-01

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

  19. 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

  20. Overview of CERES Cloud Properties Derived From VIRS AND MODIS DATA

    NASA Technical Reports Server (NTRS)

    Minis, Patrick; Geier, Erika; Wielicki, Bruce A.; Sun-Mack, Sunny; Chen, Yan; Trepte, Qing Z.; Dong, Xiquan; Doelling, David R.; Ayers, J. Kirk; Khaiyer, Mandana M.

    2006-01-01

    Simultaneous measurement of radiation and cloud fields on a global basis is recognized as a key component in understanding and modeling the interaction between clouds and radiation at the top of the atmosphere, at the surface, and within the atmosphere. The NASA Clouds and Earth s Radiant Energy System (CERES) Project (Wielicki et al., 1998) began addressing this issue in 1998 with its first broadband shortwave and longwave scanner on the Tropical Rainfall Measuring Mission (TRMM). This was followed by the launch of two CERES scanners each on Terra and Aqua during late 1999 and early 2002, respectively. When combined, these satellites should provide the most comprehensive global characterization of clouds and radiation to date. Unfortunately, the TRMM scanner failed during late 1998. The Terra and Aqua scanners continue to operate, however, providing measurements at a minimum of 4 local times each day. CERES was designed to scan in tandem with high resolution imagers so that the cloud conditions could be evaluated for every CERES measurement. The cloud properties are essential for converting CERES radiances shortwave albedo and longwave fluxes needed to define the radiation budget (ERB). They are also needed to unravel the impact of clouds on the ERB. The 5-channel, 2-km Visible Infrared Scanner (VIRS) on the TRMM and the 36-channel 1-km Moderate Resolution Imaging Spectroradiometer (MODIS) on Terra and Aqua are analyzed to define the cloud properties for each CERES footprint. To minimize inter-satellite differences and aid the development of useful climate-scale measurements, it was necessary to ensure that each satellite imager is calibrated in a fashion consistent with its counterpart on the other CERES satellites (Minnis et al., 2006) and that the algorithms are as similar as possible for all of the imagers. Thus, a set of cloud detection and retrieval algorithms were developed that could be applied to all three imagers utilizing as few channels as possible

  1. The effects of small ice crystals on the infrared radiative properties of cirrus clouds

    NASA Technical Reports Server (NTRS)

    Takano, Y.; Liou, K. N.; Asano, S.; Heymsfield, A.; Minnis, P.

    1990-01-01

    To be successful in the development of satellite retrieval methodologies for the determination of cirrus cloud properties, we must have fundamental scattering and absorption data on nonspherical ice crystals that are found in cirrus clouds. Recent aircraft observations (Platt et al. 1989) reveal that there is a large amount of small ice particles, on the order of 10 micron, in cirrus clouds. Thus it is important to explore the potential differences in the scattering and absorption properties of ice crystals with respect to their sizes and shapes. In this study the effects of nonspherical small ice crystals on the infrared radiative properties of cirrus clouds are investigated using light scattering properties of spheroidal particles. In Section 2, using the anomalous diffraction theory for spheres and results from the exact spheroid scattering program, efficient parameterization equations are developed for calculations of the scattering and absorption properties for small ice crystals. Parameterization formulas are also developed for large ice crystals using results computed from the geometric ray-tracing technique and the Fraunhofer diffraction theory for spheroids and hexagonal crystals. This is presented in Section 3. Finally, applications to the satellite remote sensing are described in Section 4.

  2. High-resolution WRF simulation of cloud properties over the super typhoon Haiyan: physics parameterizations and comparison against MODIS

    NASA Astrophysics Data System (ADS)

    Islam, Tanvir; Srivastava, Prashant K.; Dai, Qiang

    2016-11-01

    Numerical weather prediction (NWP) models can complement the satellite technology in simulating the cloud properties, especially in extreme storm events, when gathering new data becomes more than essential for accurate weather forecasting. In this study, we investigate the capability of the Weather Research and Forecasting (WRF) model to realistically simulate some important cloud properties in high-resolution grids, such as cloud phase (e.g., liquid or ice) and cloud water path. The sensitivity of different combinations of physics parameterizations to the simulated cloud fields is studied. The experiment is conducted on a super typhoon event by configuring the WRF model in two domains, with two-way nesting, allowing bidirectional information exchange between the parent and the nest. In order to do the assessment, the simulated cloud fields are compared against MODIS-derived cloud properties from one overpass scene. While the simulations have been able to capture the spatial distribution of cloud properties reasonably well, produced cloud quantities such as ice water path has been significantly overestimated when compared to the MODIS optical cloud information. The microphysics parameterizations are found to be more sensitive than the planetary boundary layer (PBL) parameterizations.

  3. How well can we monitor cloud properties over polar regions in winter?

    NASA Astrophysics Data System (ADS)

    Ackerman, S. A.; Holz, R.; Frey, R.; Heidinger, A.

    2008-12-01

    Understanding the impact of clouds on the Earth's radiation balance and detecting changes in the amount and distribution of global cloud cover requires accurate global cloud climatologies with well-characterized uncertainties. To meet this challenge, significant effort has been given to generating climate quality long-term cloud data sets using over 30 years of polar-orbiting satellite measurements [Rossow and Schiffer, 1999; Jacobowitz et al, 2003; Wylie and Menzel, 1999] with plans to continue the cloud record using the next generation of polar orbiting sensors [e.g. Ackerman, et al., 1998]. A "Climate Quality" climatology requires that both the uncertainties and the physical sensitivities are quantified and are smaller than the expected climate signature. Clouds play a critical role in the Arctic climate system, through interacting with other important climate processes, including snow/ice albedo feedback. Clouds modulate the surface radiative fluxes (Wang and Key, 2003) that influence the growth and melting of sea ice. Increasing cloud cover, which keeps the shortwave irradiances at the top-of-atmosphere unchanged, possibly compensates the reduced sea ice extent (Kato et al., 2006). However, assessing changes in polar conditions during winter has been a challenge. Holz et al (2008) presented a global two-month comparison between the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) and the Moderate Resolution Imaging Spectroradiometer (MODIS) cloud properties. Both CALIOP and MODIS are part of the NASA A-Train constellation of satellites and provide continuous near-coincident measurements that result in over 28 million cloud detection comparisons in a month. Globally (includes polar regions), it was found that the MODIS 1-km cloud mask and the CALIOP 1-km averaged layer product agreement is 88% for cloudy conditions in both August 2006 and February 2007. For clear-sky conditions the agreement is 84 (85) % for August (February). The best agreement is

  4. Aerosol effect on the evolution of the thermodynamic properties of warm convective cloud fields

    PubMed Central

    Dagan, Guy; Koren, Ilan; Altaratz, Orit; Heiblum, Reuven H.

    2016-01-01

    Convective cloud formation and evolution strongly depend on environmental temperature and humidity profiles. The forming clouds change the profiles that created them by redistributing heat and moisture. Here we show that the evolution of the field’s thermodynamic properties depends heavily on the concentration of aerosol, liquid or solid particles suspended in the atmosphere. Under polluted conditions, rain formation is suppressed and the non-precipitating clouds act to warm the lower part of the cloudy layer (where there is net condensation) and cool and moisten the upper part of the cloudy layer (where there is net evaporation), thereby destabilizing the layer. Under clean conditions, precipitation causes net warming of the cloudy layer and net cooling of the sub-cloud layer (driven by rain evaporation), which together act to stabilize the atmosphere with time. Previous studies have examined different aspects of the effects of clouds on their environment. Here, we offer a complete analysis of the cloudy atmosphere, spanning the aerosol effect from instability-consumption to enhancement, below, inside and above warm clouds, showing the temporal evolution of the effects. We propose a direct measure for the magnitude and sign of the aerosol effect on thermodynamic instability. PMID:27929097

  5. Aerosol effect on the evolution of the thermodynamic properties of warm convective cloud fields

    NASA Astrophysics Data System (ADS)

    Dagan, Guy; Koren, Ilan; Altaratz, Orit; Heiblum, Reuven H.

    2016-12-01

    Convective cloud formation and evolution strongly depend on environmental temperature and humidity profiles. The forming clouds change the profiles that created them by redistributing heat and moisture. Here we show that the evolution of the field’s thermodynamic properties depends heavily on the concentration of aerosol, liquid or solid particles suspended in the atmosphere. Under polluted conditions, rain formation is suppressed and the non-precipitating clouds act to warm the lower part of the cloudy layer (where there is net condensation) and cool and moisten the upper part of the cloudy layer (where there is net evaporation), thereby destabilizing the layer. Under clean conditions, precipitation causes net warming of the cloudy layer and net cooling of the sub-cloud layer (driven by rain evaporation), which together act to stabilize the atmosphere with time. Previous studies have examined different aspects of the effects of clouds on their environment. Here, we offer a complete analysis of the cloudy atmosphere, spanning the aerosol effect from instability-consumption to enhancement, below, inside and above warm clouds, showing the temporal evolution of the effects. We propose a direct measure for the magnitude and sign of the aerosol effect on thermodynamic instability.

  6. Aerosol effect on the evolution of the thermodynamic properties of warm convective cloud fields.

    PubMed

    Dagan, Guy; Koren, Ilan; Altaratz, Orit; Heiblum, Reuven H

    2016-12-08

    Convective cloud formation and evolution strongly depend on environmental temperature and humidity profiles. The forming clouds change the profiles that created them by redistributing heat and moisture. Here we show that the evolution of the field's thermodynamic properties depends heavily on the concentration of aerosol, liquid or solid particles suspended in the atmosphere. Under polluted conditions, rain formation is suppressed and the non-precipitating clouds act to warm the lower part of the cloudy layer (where there is net condensation) and cool and moisten the upper part of the cloudy layer (where there is net evaporation), thereby destabilizing the layer. Under clean conditions, precipitation causes net warming of the cloudy layer and net cooling of the sub-cloud layer (driven by rain evaporation), which together act to stabilize the atmosphere with time. Previous studies have examined different aspects of the effects of clouds on their environment. Here, we offer a complete analysis of the cloudy atmosphere, spanning the aerosol effect from instability-consumption to enhancement, below, inside and above warm clouds, showing the temporal evolution of the effects. We propose a direct measure for the magnitude and sign of the aerosol effect on thermodynamic instability.

  7. Investigation of cloud properties and atmospheric stability with MODIS

    NASA Technical Reports Server (NTRS)

    Menzel, P.; Ackerman, S.; Moeller, C.; Gumley, L.; Strabala, K.; Frey, R.; Prins, E.; LaPorte, D.; Lynch, M.

    1996-01-01

    The last half year was spent in preparing Version 1 software for delivery, and culminated in transfer of the Level 2 cloud mask production software to the SDST in April. A simulated MODIS test data set with good radiometric integrity was produced using MAS data for a clear ocean scene. ER-2 flight support and MAS data processing were provided by CIMSS personnel during the Apr-May 96 SUCCESS field campaign in Salina, Kansas. Improvements have been made in the absolute calibration of the MAS, including better characterization of the spectral response for all 50 channels. Plans were laid out for validating and testing the MODIS calibration techniques; these plans were further refined during a UW calibration meeting with MCST.

  8. Satellite and Surface Data Synergy for Developing a 3D Cloud Structure and Properties Characterization Over the ARM SGP. Stage 1: Cloud Amounts, Optical Depths, and Cloud Heights Reconciliation

    NASA Technical Reports Server (NTRS)

    Genkova, I.; Long, C. N.; Heck, P. W.; Minnis, P.

    2003-01-01

    One of the primary Atmospheric Radiation Measurement (ARM) Program objectives is to obtain measurements applicable to the development of models for better understanding of radiative processes in the atmosphere. We address this goal by building a three-dimensional (3D) characterization of the cloud structure and properties over the ARM Southern Great Plains (SGP). We take the approach of juxtaposing the cloud properties as retrieved from independent satellite and ground-based retrievals, and looking at the statistics of the cloud field properties. Once these retrievals are well understood, they will be used to populate the 3D characterization database. As a first step we determine the relationship between surface fractional sky cover and satellite viewing angle dependent cloud fraction (CF). We elaborate on the agreement intercomparing optical depth (OD) datasets from satellite and ground using available retrieval algorithms with relation to the CF, cloud height, multi-layer cloud presence, and solar zenith angle (SZA). For the SGP Central Facility, where output from the active remote sensing cloud layer (ARSCL) valueadded product (VAP) is available, we study the uncertainty of satellite estimated cloud heights and evaluate the impact of this uncertainty for radiative studies.

  9. Histotripsy-Induced Cavitation Cloud Initiation Thresholds in Tissues of Different Mechanical Properties

    PubMed Central

    Vlaisavljevich, Eli; Maxwell, Adam; Warnez, Matthew; Johnsen, Eric; Cain, Charles A.; Xu, Zhen

    2014-01-01

    Histotripsy is an ultrasound ablation method that depends on the initiation and maintenance of a cavitation bubble cloud to fractionate soft tissue. This paper studies how tissue properties impact the pressure threshold to initiate the cavitation bubble cloud. Our previous study showed that shock scattering off one or more initial bubbles, expanded to sufficient size in the focus, plays an important role in initiating a dense cavitation cloud. In this process, the shock scattering causes the positive pressure phase to be inverted, resulting in a scattered wave that has the opposite polarity of the incident shock. The inverted shock is superimposed on the incident negative pressure phase to form extremely high negative pressures, resulting in a dense cavitation cloud growing toward the transducer. We hypothesize that increased tissue stiffness impedes the expansion of initial bubbles, reducing the scattered tensile pressure, and thus requiring higher initial intensities for cloud initiation. To test this hypothesis, 5-cycle histotripsy pulses at pulse repetition frequencies (PRFs) of 10, 100, or 1000 Hz were applied by a 1-MHz transducer focused inside mechanically tunable tissue-mimicking agarose phantoms and various ex vivo porcine tissues covering a range of Young’s moduli. The threshold to initiate a cavitation cloud and resulting bubble expansion were recorded using acoustic backscatter detection and optical imaging. In both phantoms and ex vivo tissue, results demonstrated a higher cavitation cloud initiation threshold for tissues of higher Young’s modulus. Results also demonstrated a decrease in bubble expansion in phantoms of higher Young’s modulus. These results support our hypothesis, improve our understanding of the effect of histotripsy in tissues with different mechanical properties, and provide a rational basis to tailor acoustic parameters for fractionation of specific tissues. PMID:24474139

  10. Impact of Deforestation on Cloud Properties and Rainfall Over the Costa Rica-Nicaraguan region

    NASA Astrophysics Data System (ADS)

    Ray, D. K.; Nair, U. S.; Welch, R. M.; Lawton, R. O.

    2002-12-01

    The Nicaraguan-Costa Rican region in Central America exhibits the typical pattern of complex deforestation now seen throughout the tropics. The region is a mixture of lowland, mostly converted to agriculture, and mountainous regions, where pristine forests still persist. At present the northern fertile plains of Costa Rica are mostly utilized for agriculture. However in the adjacent regions of southern Nicaragua lowland forests are relatively intact. The extensive agricultural areas of northern Costa Rica is a region of discontinuity in the proposed Mesoamerican Biological Corridor which would connect the montane forests in Costa Rica to the lowland forests in Nicaragua. The present study is part of a larger study which investigates the effects of continuing lowland deforestation and associated regional climate change in Central America on the stability of the entire proposed Mesoamerican Biological Corridor. The present work focuses on the effects of land use on the formation of cloudiness, cloud properties and rainfall in the forested regions of southern Nicaragua and the deforested regions of northern Costa Rica. Land surface and cloud properties are retrieved using the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) satellite data and products. The land surface properties retrieved are land surface temperature, albedo, Normalized Difference Vegetation Index (NDVI), Available Soil Moisture fraction and surface energy fluxes. The cloud properties retrieved are cloud optical thickness and effective radii. In addition, the frequency of cumulus cloudiness on hourly basis are derived from the Geostationary Operational Environmental Satellite (GOES) and rainfall is studied using Tropical Rainfall Measuring Mission (TRMM) satellite products. The correlations between the surface properties, cloud properties, cumulus cloudiness and rainfall as a function of ecosystem and topography is

  11. Remote Sensing of Cloud, Aerosol, and Land Properties from MODIS: Applications to the East Asia Region

    NASA Technical Reports Server (NTRS)

    King, Michael D.; Platnick, Steven; Moody, Eric G.

    2002-01-01

    MODIS is an earth-viewing cross-track scanning spectroradiometer launched on the Terra satellite in December 1999 and the Aqua satellite in May 2002. MODIS scans a swath width sufficient to provide nearly complete global coverage every two days from a polar-orbiting, sun-synchronous, platform at an altitude of 705 km, and provides images in 36 spectral bands between 0.415 and 14.235 microns with spatial resolutions of 250 m (2 bands), 500 m (5 bands) and 1000 m (29 bands). These bands have been carefully selected to enable advanced studies of land, ocean, and atmospheric processes. In this paper we will describe the various methods being used for the remote sensing of cloud, aerosol, and surface properties using MODIS data, focusing primarily on (i) the MODIS cloud mask used to distinguish clouds, clear sky, heavy aerosol, and shadows on the ground, (ii) cloud optical properties, especially cloud optical thickness and effective radius of water drops and ice crystals, (iii) aerosol optical thickness and size characteristics both over land and ocean, and (iv) ecosystem classification and surface spectral reflectance. The physical principles behind the determination of each of these products will be described, together with an example of their application using MODIS observations to the east Asian region. All products are archived into two categories: pixel-level retrievals (referred to as Level-2 products) and global gridded products at a latitude and longitude resolution of 1 min (Level-3 products).

  12. Cloud radiative properties over the South Pole from AVHRR infrared data

    SciTech Connect

    Lubin, D.; Harper, D.A.

    1996-12-01

    Over the Antarctic plateau, the radiances measured by the AVHRR middle infrared (11 and 12 {mu}m) channels are shown to depend on effective cloud temperature, emissivity, ice water path, and effective radius of the particle size distribution. The usefulness of these dependencies is limited by radiometric uncertainties of up to 2 K in brightness temperature and by the fact that the radiative transfer solutions are not single valued over all possible ranges of temperature, effective radius, and ice water path. Despite these limitations, AVHRR imagery can be used to characterize cloud optical properties over the Antarctic continent if surface weather observations and/or radiosonde data can be collocated with the satellite overpasses. From AVHRR imagery covering the South Pole during 1992, the mean cloud emissivity is estimated at 0.43 during summer and 0.37 during winter, while the mean summer and winter effective radii are estimated at 12.3 and 5.6 {mu}m. respectively. When a radiative transfer model is used to evaluate these results in comparison with surface pyrgeometer measurements, the comparison suggests that the AVHRR retrieval method captures the overall seasonal behavior in cloud properties. During months when the polar vortex persists, AVHRR infrared radiances may be noticeably influenced by polar stratospheric clouds. 26 refs., 12 figs., 3 tabs.

  13. Ice cloud properties in ice-over-water cloud systems using Tropical Rainfall Measuring Mission (TRMM) visible and infrared scanner and TRMM Microwave Imager data

    NASA Astrophysics Data System (ADS)

    Minnis, Patrick; Huang, Jianping; Lin, Bing; Yi, Yuhong; Arduini, Robert F.; Fan, Tai-Fang; Ayers, J. Kirk; Mace, Gerald G.

    2007-03-01

    A multilayered cloud retrieval system (MCRS) is updated and used to estimate ice water path in maritime ice-over-water clouds using Visible and Infrared Scanner (VIRS) and Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) measurements acquired over the Tropics between January and August 1998. Lookup tables of top-of-atmosphere 0.65-μm reflectance are developed for ice-over-water cloud systems using radiative transfer calculations for various combinations of ice-over-water cloud layers. The liquid and ice water paths, LWP and IWP, respectively, are determined with the MCRS using these lookup tables with a combination of microwave (MW), visible (VIS), and infrared (IR) data. LWP, determined directly from the TMI MW data, is used to define the lower-level cloud properties to select the proper lookup table. The properties of the upper-level ice clouds, such as optical depth and effective size, are then derived using the Visible-Infrared Solar-infrared Split-Window technique (VISST), which matches the VIRS IR, 3.9 μm, and VIS data to the multilayer cloud lookup table reflectances and a set of emittance parameterizations. Initial comparisons with surface-based radar retrievals suggest that this enhanced MCRS can significantly improve the accuracy and decrease the IWP in overlapped clouds by 42 and 13% compared to using the single-layer VISST and an earlier simplified MW-VIS-IR (MVI) differencing method, respectively, for ice-over-water cloud systems. The tropical distribution of ice-over-water clouds is the same as derived earlier from combined TMI and VIRS data, but the new values of IWP and optical depth are slightly larger than the older MVI values and exceed those of single-layered clouds by 7 and 11%, respectively. The mean IWP from the MCRS is 8-14% greater than that retrieved from radar retrievals of overlapped clouds over two surface sites, and the standard deviations of the differences are similar to those for single-layered clouds. Examples of

  14. Optimization and Statistical Evaluation of GOES Cloud-Top Properties for Nowcasting Lightning Initiation

    DTIC Science & Technology

    2010-03-01

    Adapted from Williams (1988) and COMET (2005)]............... 4 Figure 3. Electrical structure of thunderstorms across three varying regions and two...varying seasons from Krehbiel (1986). ................................... 9 Figure 4. Convective cloud properties as depicted by GOES-12’s visible ... Visible xviii THIS PAGE INTENTIONALLY LEFT BLANK xix ACKNOWLEDGMENTS After months of seemingly endless work, one tends to accumulate a

  15. Ice clouds optical properties in the Far Infrared from the ECOWAR-COBRA Experiment

    NASA Astrophysics Data System (ADS)

    Rizzi, Rolando; Tosi, Ennio

    ECOWAR-COBRA (Earth COoling by WAter vapouR emission -Campagna di Osservazioni della Banda Rotazionale del vapor d'Acqua) field campaign took place in Italy from 3 to 17 March 2007 with the main goal of studying the scarcely sensed atmospheric emission occurring beyond 17 microns. Instrumentation involved in the campaign included two different Fourier Transforms Spectrometers (FTS) : REFIR-PAD (at Testa Grigia Station, 3500 m a.s.l.) and FTIR-ABB (at Cervinia Station, 1990 m a.s.l.). In this work cloudy sky data have been ana-lyzed. A cloud properties retrieval methodology (RT-RET), based on high spectral resolution measurements in the atmospheric window (800-1000 cm-1), is applied to both FTS sensors. Cloud properties determined from the infrared retrievals are compared with those obtained from Raman lidar taken by the BASIL Lidar system that was operating at Cervinia station. Cloud microphysical and optical properties retrieved by RT-RET are used to perform forward simulations over the entire FTSs measurements spectral interval. Results are compared to FTS data to test the ability of single scattering ice crystals models to reproduce cloudy sky radiances in the Far Infra-Red (FIR) part of the spectrum. New methods to retrieve cloud optical and microphysical properties exploiting high spectral resolution FIR measurements are also investigated.

  16. Retrieval of Cirrus Cloud Radiative and Backscattering Properties Using Combined Lidar and Infrared Radiometer (LIRAD) Measurements

    SciTech Connect

    Comstock, Jennifer M.; Sassen, Kenneth

    2001-10-01

    A method for retrieval of cirrus macrophysical and radiative properties using combined ruby lidar and infrared radiometer measurements is explained in detail. The retrieval algorithm includes estimation of a variable backscatter-to-extinction ratio for each lidar profile, which accounts for changes in cloud microphysical properties with time. The technique also utilizes a correlated K distribution radiative transfer model,where absorption coefficients K have been tabulated specifically for the bandwidth and filter function of the infrared radiometer. The radiative transfer model allows for estimation of infrared emission due to atmospheric water vapor,ozone,and carbon dioxide, which is essential for deriving cirrus radiative properties. Also described is an improved technique for estimation of upwelling IR radiation that is emitted by the surface of the earth and reflected by the cloud into the radiometer field-of-view. Derived cirrus cloud properties include base and top height and temperature, visible optical depth, emittance, backscatter-to-extinction ratio, and extinction-to-absorption ratio. The purpose of this algorithm is to facilitate the analysis of the extensive high-cloud dataset obtained at the University of Utah, Facility for Atmospheric Remote Sensing in Salt Lake City, UT. To illustrate the method, a cirrus case study is presented.

  17. Aerosol Impacts on Microphysical and Radiative Properties of Stratocumulus Clouds in the Southeast Pacific

    NASA Astrophysics Data System (ADS)

    Twohy, C. H.; Toohey, D. W.; Andrejczuk, M.; Anderson, J. R.; Adams, A.; Lytle, M.; George, R.; Wood, R.; Zuidema, P.; Leon, D.

    2011-12-01

    The southeast Pacific Ocean is covered by the world's largest stratocumulus cloud layer, which has a strong impact on ocean temperatures and climate in the region. The effect of anthropogenic sources of aerosol particles was investigated during the VOCALS field experiment. Aerosol measurements below and above cloud were made with a ultra-high sensitivity aerosol spectrometer and analytical electron microscopy. In addition to more standard in-cloud measurements, cloud droplets were collected and evaporated using a counterflow virtual impactor (CVI), and the non-volatile residual particles were analyzed. Many flights focused on the gradient in cloud properties along an E-W track from near the Chilean coast to remote areas offshore. Mean statistics from seven flights were compiled. Consistent with a continental source of cloud condensation nuclei, below-cloud accumulation-mode aerosol and droplet number concentration generally decreased from near shore to offshore. The effect extends ~800 to 1000 km from shore. The additional particles are mainly sulfates from anthropogenic sources. Liquid water content and drizzle concentration tended to increase with distance from shore, but exhibited much greater variability. Analysis of the droplet residual measurements showed that not only were there more residual nuclei near shore, but that they tended to be larger than those offshore. Single particle analysis over a broad particle size range was used to reveal types and sources of CCN, which were primarily sulfates near shore. Differences in the size distribution of droplet residual particles and ambient aerosol particles were observed due to the preferential activation of large aerosol particles. By progressively excluding small droplets from the CVI sample, we were able to show that the larger drops, which initiate drizzle, contain the largest aerosol particles. However, the scavenging efficiency is not sharp as expected from a simple parcel activation model. A wide range of

  18. Terahertz Remote Sensing of Ice Clouds - Sensitivity on Ice Dielectric Properties

    NASA Astrophysics Data System (ADS)

    Mendrok, J.; Baron, P.; Kasai, Y.

    2007-12-01

    Initiated by current developments in terahertz sensor technology the application of instruments operating in the spectral region between 0.1 - 30 THz is considered for a number of remote sensing issues. Accounting for more than 50 percent of the outgoing longwave radiation and with the major component of cirrus radiative forcing in the far-infrared, satellite measurements in this spectral region will significantly support the determination of the radiation budget of the Earth. Furthermore, spanning the whole range of particle sizes found in tropospheric ice clouds, the Terahertz region bears the potential to complement existing methods and improve our knowlegde and understanding of those clouds. Both, determination of the Earth's radiation budget as well as retrieving ice cloud properties require appropriately accurate calculations of radiative transfer. Hence, a good knowledge of the input parameters to the radiative transfer models is needed. In particular, this includes spectrally dependent properties of the molecular as well as particulate atmospheric matter, i.e., spectroscopic parameters of the molecular absorption lines and continua as well as the dielectric properties of aerosol and cloud particle material. Due to the lack of Terahertz light source and receiver technology in the past, measurements of these parameters have been sparse and the knowledge about them is rather poor. In preparation to evaluate the feasibility of monitoring tropospheric ice clouds using passive Terahertz observations, we study the modeling uncertainties due to the unconfident knowledge of the complex refractive index of ice. We give an overview of the consistency and discrepancies, respectively, of the existing measurements and models for ice refractive index in the Terahertz region. Using calculations of particle optical properties according to Mie theory as well as the radiative transfer models Moliere and SARTre, we estimate the deviations in particle optical properties and

  19. Radiative forcing of climate in the western Antarctic Peninsula: Effects of cloud, surface, and aerosol properties

    NASA Astrophysics Data System (ADS)

    Payton, Allison Mccomiskey

    2003-12-01

    Polar regions are expected to show early and extreme responses to a rise in average global temperatures. The region west of the Antarctic Peninsula has shown a significant rise in temperature of the past half century while temperatures over the rest of the continent are decreasing. Approximately half of the warming over the western Antarctic Peninsula has been explained by changes in atmospheric circulation. This research has examined local climate feedback processes involving aerosols, clouds, and surface properties relative to sea ice cover, to explain the remainder of the warming, and addresses the most appropriate approach in examining local radiative processes. Two data sets are used: a highly resolved ground-based data set from the spring and summer season of 1999 2000 at Palmer Station, Antarctica and a 14 year satellite-derived data set. A three- dimensional radiative transfer model is shown to perform better than the plane-parallel models traditionally used for this application. Aerosol concentrations are low, as expected, and have a typical optical depth of 0.05 which has little effect on surface radiation budgets and climate feedback processes. An absorption process is found on three clear-sky days that accounts for 5 20 W·m-2 of energy absorbed by the atmosphere. The absorption process is of unknown origin. Cloud properties over the short- and long-term were found to be invariant with time and changes in temperature except in the summer season. Cloud radiative forcing was negative throughout the 14 year time period, but the majority of this effect was attributed to changes in surface properties (decreasing reflectance) rather than increasing cloud amount or thickness. The trend in cloud cover over the long-term and the effect of clouds on climate appears to be different in the region of the western Antarctic Peninsula than in the Arctic.

  20. Determination of bulk properties of tropical cloud clusters from large scale heat and moisture budgets, appendix B

    NASA Technical Reports Server (NTRS)

    Yanai, M.; Esbensen, S.; Chu, J.

    1972-01-01

    The bulk properties of tropical cloud clusters, as the vertical mass flux, the excess temperature, and moisture and the liquid water content of the clouds, are determined from a combination of the observed large-scale heat and moisture budgets over an area covering the cloud cluster, and a model of a cumulus ensemble which exchanges mass, heat, vapor and liquid water with the environment through entrainment and detrainment. The method also provides an understanding of how the environmental air is heated and moistened by the cumulus convection. An estimate of the average cloud cluster properties and the heat and moisture balance of the environment, obtained from 1956 Marshall Islands data, is presented.

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

    SciTech Connect

    Richard A. Ferrare; David D. Turner

    2011-09-01

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

  2. Properties of Low Metallicity Molecular Clouds: A 0.3 Parsec Resolution Map of SMC B1 #1

    NASA Astrophysics Data System (ADS)

    Rodea, Uriel

    2017-01-01

    Stars form in molecular clouds, therefore understanding their structure is important in understanding this key process in galaxy evolution. Studies of clouds in the Milky Way have provided insight to their internal structures, but until recently we have not been able to study clouds in low metallicity conditions at the same resolution. We use the Atacama Large Millimeter Array to map a molecular cloud in the nearby, low metallicity galaxy the SMC at 0.3 pc spatial resolution in 12CO (2-1). We use the CPROPS algorithm (Rosolowsky & Leroy 2006) to measure structural properties of the cloud (mass, size, velocity dispersion, temperature) and compare to molecular clouds in the Milky Way observed at comparable resolution. We present the results of this comparison and discuss the CO-to-H2 conversion factor, virial parameter and mass-radius-velocity dispersion relationships (i.e. Larson's Laws) for the cloud.

  3. An Airborne A-Band Spectrometer for Remote Sensing Of Aerosol and Cloud Optical Properties

    NASA Technical Reports Server (NTRS)

    Pitts, Michael; Hostetler, Chris; Poole, Lamont; Holden, Carl; Rault, Didier

    2000-01-01

    Atmospheric remote sensing with the O2 A-band has a relatively long history, but most of these studies were attempting to estimate surface pressure or cloud-top pressure. Recent conceptual studies have demonstrated the potential of spaceborne high spectral resolution O2 A-band spectrometers for retrieval of aerosol and cloud optical properties. The physical rationale of this new approach is that information on the scattering properties of the atmosphere is embedded in the detailed line structure of the O2 A-band reflected radiance spectrum. The key to extracting this information is to measure the radiance spectrum at very high spectral resolution. Instrument performance requirement studies indicate that, in addition to high spectral resolution, the successful retrieval of aerosol and cloud properties from A-band radiance spectra will also require high radiometric accuracy, instrument stability, and high signal-to-noise measurements. To experimentally assess the capabilities of this promising new remote sensing application, the NASA Langley Research Center is developing an airborne high spectral resolution A-band spectrometer. The spectrometer uses a plane holographic grating with a folded Littrow geometry to achieve high spectral resolution (0.5 cm-1) and low stray light in a compact package. This instrument will be flown in a series of field campaigns beginning in 2001 to evaluate the overall feasibility of this new technique. Results from these campaigns should be particularly valuable for future spaceborne applications of A-band spectrometers for aerosol and cloud retrievals.

  4. A Two-Habit Ice Cloud Optical Property Parameterization for GCM Application

    NASA Technical Reports Server (NTRS)

    Yi, Bingqi; Yang, Ping; Minnis, Patrick; Loeb, Norman; Kato, Seiji

    2014-01-01

    We present a novel ice cloud optical property parameterization based on a two-habit ice cloud model that has been proved to be optimal for remote sensing applications. The two-habit ice model is developed with state-of-the-art numerical methods for light scattering property calculations involving individual columns and column aggregates with the habit fractions constrained by in-situ measurements from various field campaigns. Band-averaged bulk ice cloud optical properties including the single-scattering albedo, the mass extinction/absorption coefficients, and the asymmetry factor are parameterized as functions of the effective particle diameter for the spectral bands involved in the broadband radiative transfer models. Compared with other parameterization schemes, the two-habit scheme generally has lower asymmetry factor values (around 0.75 at the visible wavelengths). The two-habit parameterization scheme was widely tested with the broadband radiative transfer models (i.e. Rapid Radiative Transfer Model, GCM version) and global circulation models (GCMs, i.e. Community Atmosphere Model, version 5). Global ice cloud radiative effects at the top of the atmosphere are also analyzed from the GCM simulation using the two-habit parameterization scheme in comparison with CERES satellite observations.

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

    DOE PAGES

    Pistone, Kristina; Praveen, Puppala S.; Thomas, Rick 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. 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

  7. 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.

    2016-04-27

    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) 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

  8. Influence of 3D Radiative Effects on Satellite Retrievals of Cloud Properties

    NASA Technical Reports Server (NTRS)

    Varnai, Tamas; Marshak, Alexander; Einaudi, Franco (Technical Monitor)

    2001-01-01

    When cloud properties are retrieved from satellite observations, the calculations apply 1D theory to the 3D world: they only consider vertical structures and ignore horizontal cloud variability. This presentation discusses how big the resulting errors can be in the operational retrievals of cloud optical thickness. A new technique was developed to estimate the magnitude of potential errors by analyzing the spatial patterns of visible and infrared images. The proposed technique was used to set error bars for optical depths retrieved from new MODIS measurements. Initial results indicate that the 1 km resolution retrievals are subject to abundant uncertainties. Averaging over 50 by 50 km areas reduces the errors, but does not remove them completely; even in the relatively simple case of high sun (30 degree zenith angle), about a fifth of the examined areas had biases larger than ten percent. As expected, errors increase substantially for more oblique illumination.

  9. Clouds of ammonia ice - Laboratory measurements of the single-scattering properties

    NASA Technical Reports Server (NTRS)

    Pope, Shelly K.; Tomasko, Martin G.; Williams, Michael S.; Perry, Marcus L.; Doose, Lyn R.; Smith, Peter H.

    1992-01-01

    A new apparatus for the growth of clouds of ammonia and water ice has been developed which represents an improvement over the one constructed by Holmes (1981). Better thermal control of the cloud chamber has been achieved so that colder temperature relevant to the outer planets' atmospheres could be reached. The angular resolution of the scattering measurements has been improved from 10 deg to about 2 deg. A rotating filter wheel combined with a much larger computer allows a complete data set to be collected in three colors once per second. This capability is important in monitoring cloud properties as they change with time and in collecting data on larger crystals which can fall through the beam in a few seconds.

  10. “Lidar Investigations of Aerosol, Cloud, and Boundary Layer Properties Over the ARM ACRF Sites”

    SciTech Connect

    Ferrare, Richard; Turner, David

    2015-01-13

    Project goals; Characterize the aerosol and ice vertical distributions over the ARM NSA site, and in particular to discriminate between elevated aerosol layers and ice clouds in optically thin scattering layers; Characterize the water vapor and aerosol vertical distributions over the ARM Darwin site, how these distributions vary seasonally, and quantify the amount of water vapor and aerosol that is above the boundary layer; Use the high temporal resolution Raman lidar data to examine how aerosol properties vary near clouds; Use the high temporal resolution Raman lidar and Atmospheric Emitted Radiance Interferometer (AERI) data to quantify entrainment in optically thin continental cumulus clouds; and Use the high temporal Raman lidar data to continue to characterize the turbulence within the convective boundary layer and how the turbulence statistics (e.g., variance, skewness) is correlated with larger scale variables predicted by models.

  11. Satellite-based Assessment of Global Warm Cloud Properties Associated with Aerosols, Atmospheric Stability, and Diurnal Cycle

    NASA Technical Reports Server (NTRS)

    Matsui, Toshihisa; Masunaga, Hirohiko; Kreidenweis, Sonia M.; Pielke, Roger A., Sr.; Tao, Wei-Kuo; Chin, Mian; Kaufman, Yoram J.

    2006-01-01

    This study examines variability in marine low cloud properties derived from semi-global observations by the Tropical Rainfall Measuring Mission (TRMM) satellite, as linked to the aerosol index (AI) and lower-tropospheric stability (LTS). AI is derived from the Moderate Resolution Imaging Spectroradiometer (Terra MODIS) sensor and the Goddard Chemistry Aerosol Radiation and Transportation (GOCART) model, and is used to represent column-integrated aerosol concentrations. LTS is derived from the NCEP/NCAR reanalysis, and represents the background thermodynamic environment in which the clouds form. Global statistics reveal that cloud droplet size tends to be smallest in polluted (high-AI) and strong inversion (high-LTS) environments. Statistical quantification shows that cloud droplet size is better correlated with AI than it is with LTS. Simultaneously, the cloud liquid water path (CLWP) tends to decrease as AI increases. This correlation does not support the hypothesis or assumption that constant or increased CLWP is associated with high aerosol concentrations. Global variability in corrected cloud albedo (CCA), the product of cloud optical depth and cloud fraction, is very well explained by LTS, while both AI and LTS are needed to explain local variability in CCA. Most of the local correlations between AI and cloud properties are similar to the results from the global statistics, while weak anomalous aerosol-cloud correlations appear locally in the regions where simultaneous high (low) AI and low (high) LTS compensate each other. Daytime diurnal cycles explain additional variability in cloud properties. CCA has the largest diurnal cycle in high-LTS regions. Cloud droplet size and CLWP have weak diurnal cycles that differ between clean and polluted environments. The combined results suggest that investigations of marine low cloud radiative forcing and its relationship to hypothesized aerosol indirect effects must consider the combined effects of aerosols

  12. Typical and Unusual Properties of Magnetic Clouds during the WIND Era

    NASA Technical Reports Server (NTRS)

    Lepping, R. P.; Berdichevsky, D.; Szabo, A.; Burlaga, L. F.; Thompson, B. J.; Mariani, F.; Lazarus, A. J.; Steinberg, J. T.

    1999-01-01

    A list of 33 magnetic clouds as identified in WIND magnetic field and plasma data has been compiled. The intervals for these events are provided as part of NASA/GSFC, WIND-MFI's Website under the URL http://lepmfi.qsfc.nasa.gov/mfi/mag_cloud publ.html#table The period covered in this study is from early 1995 to November 1998 which primarily occurs in the quiet part of the solar cycle. A force free, cylindrically symmetric, magnetic field model has been applied to the field data in 1-hour averaged form for all of these events (except one small event where 10 min avg's were used) and the resulting fit-parameters examined. Each event was provided a semi-quantitatively determined quality factor (excellent, good or poor). A set of 28 good or better cases, spanning a surprisingly large range of values for its various properties, was used for further analysis. These properties are, for example, durations, attitudes, sizes, asymmetries, axial field strengths, speeds, and relative impact parameters. They will be displayed and analyzed, along with some related derived quantities, with emphasis on typical vs unusual properties and on the magnetic fields magnetic clouds' relationships to the Sun and to upstream interplanetary shocks, where possible. For example, it is remarkable how narrowly distributed the speeds of these clouds are, and the overall average speed (390 techniques km/s) is less than that normally quoted for the average solar wind speed (420 km/s) despite the fact that many of these clouds are d"drivers" of interplanetary shocks. On average, a cloud appears to be a little less symmetric when the spacecraft is able to pass close to the cloud's axis as compared to a farther out passage. The average longitude and latitude (in GSE) of the axes of the clouds are 85 degrees and 8 degrees, respectively, with standard deviations near 40 degrees. Also, the half=yearly averaged axial magnetic flux has approximately tripled. almost monotonically, from about 6 to 17 X 10

  13. Retrieval of Venus' clouds and hazes properties with polarimetric data from SPICAV/VEx

    NASA Astrophysics Data System (ADS)

    Rossi, L.; Marcq, E.; Bott, N.; Montmessin, F.; Fedorova, A.; Stam, D.; Bertaux, J.-L.; Korablev, O.

    2015-10-01

    The study of Venus' cloud layers is important in order to understand the structure, radiative balance and dynamics of the Venusian atmosphere. Polarization measurements have given important constraints for the determination of the constituents of the clouds and haze. From ground based observations, Hansen and Hovenier[3], using a radiative transfer model including polarization, found that the main cloud layers between 50 and 70 km consist of r˜1μm radius spherical droplets of a H 2SO4-H2O solution. In the early 1980s, Kawabata[4] used the polarization data from the OCPP instrument on the spacecraft Pioneer Venus to constrain the properties of the overlying haze. They found that the haze layer is composed of smaller particles with r˜0.25μm and similar refractive indices. Our work reproduces the method used by Hansen and Kawabata[3, 4]. We applied a radiative transfer model with polarization on the polarization data of the SPICAV-IR instrument on-board ESA's Venus Express. Our aim is to better constrain haze and cloud particles at the top of Venus's clouds, as well as their spatial and temporal variability.

  14. Computation of the Effects of Inhomogeneous Clouds on Retrieval of Remotely Sensed Properties

    NASA Technical Reports Server (NTRS)

    Chambers, Lin H.

    1998-01-01

    Current and future earth observation programs depend on satellite measurements of radiance to retrieve the properties of clouds on a global basis. At present, this retrieval is made assuming that the clouds in the instrument field of view are plane parallel and independent of adjacent pixels. While this assumption is known to be false except in very limited cases, its impact can be evaluated, and if possible corrected, based on emerging theoretical techniques. In this study, the Spherical Harmonic Discrete Ordinate Method (SHDOM, Evans, 1996) has been used to assess the sensitivity of the retrieval to a variety of cloud parameters. SHDOM allows the plane parallel assumption to be relaxed and makes 2D and even 3D radiative solutions practical. A previous study (Chambers et al., 1996) assessed the effect of horizontal inhomogeneity in 45 LANDSAT scenes of boundary layer clouds over ocean. The four scenes studied here represent overcast, broken, scattered and strongly thermally forced cloud fields and are used to perform sensitivity studies to a wider variety of parameters. Comparisons are made at three solar zenith angles (theta (sub 0) = 0, 49, and 63 degrees) to avoid ambiguity in the results due to solar zenith angle.

  15. Methods of editing cloud and atmospheric layer affected pixels from satellite data

    NASA Technical Reports Server (NTRS)

    Nixon, P. R. (Principal Investigator); Wiegand, C. L.; Richardson, A. J.; Johnson, M. P.

    1981-01-01

    Plotted transects made from south Texas daytime HCMM data show the effect of subvisible cirrus (SCI) clouds in the emissive (IR) band but the effect is unnoticable in the reflective (VIS) band. The depression of satellite indicated temperatures ws greatest in the center of SCi streamers and tapered off at the edges. Pixels of uncontaminated land and water features in the HCMM test area shared identical VIS and IR digital count combinations with other pixels representing similar features. A minimum of 0.015 percent repeats of identical VIS-IR combinations are characteristic of land and water features in a scene of 30 percent cloud cover. This increases to 0.021 percent of more when the scene is clear. Pixels having shared VIS-IR combinations less than these amounts are considered to be cloud contaminated in the cluster screening method. About twenty percent of SCi was machine indistinguishable from land features in two dimensional spectral space (VIS vs IR).

  16. The clouds are hazes of Venus

    NASA Technical Reports Server (NTRS)

    Esposito, L. W.; Knollenberg, R. G.; Marov, M. IA.; Toon, O. B.; Turco, R. P.

    1983-01-01

    Pioneer Venus and Venera probe data for the clouds of Venus are considered. These clouds consist of a main cloud deck at 45-70 km altitude, with thinner hazes above and below, although the microphysical properties of the main cloud are further subdivided into upper, middle and lower cloud levels. Much of the cloud exhibits a multimodal particle size distribution, with the mode most visible from the earth being H2SO4 droplets having 2-3 micron diameters. Despite variations, the vertical structure of the clouds indicates persistent features at sites separated by years and by great distances. The clouds are more strongly affected by radiation than by latent heat release, and the small particle size and weak convective activity observed are incompatible with lightning of cloud origin.

  17. A study of the starless dark cloud LDN 1570: Distance, dust properties, and magnetic field geometry

    NASA Astrophysics Data System (ADS)

    Eswaraiah, C.; Maheswar, G.; Pandey, A. K.; Jose, J.; Ramaprakash, A. N.; Bhatt, H. C.

    2013-08-01

    Aims: We aim to map the magnetic field geometry and to study the dust properties of the starless cloud, L1570, using multi-wavelength optical polarimetry and photometry of the stars projected on the cloud. Methods: The direction of the magnetic field component parallel to the plane of the sky of a cloud can be obtained using polarimetry of the stars projected on and located behind the cloud. It is believed that the unpolarized light from the stars background to the cloud undergoes selective extinction while passing through non-spherical dust grains that are aligned with their minor axes parallel to the cloud magnetic field. The emerging light becomes partially plane polarized. The observed polarization vectors trace the direction of the projected magnetic field of the cloud. We made R-band imaging polarimetry of the stars projected on a cloud, L1570, to trace the magnetic field orientation. We also made multi-wavelength polarimetric and photometric observations to constrain the properties of dust in L1570. Results: We estimated a distance of 394 ± 70 pc to the cloud using 2MASS JHKs colors. Using the values of the Serkowski parameters, σ1, overlineɛ, λmax, and the position of the stars on the near-infrared color-color diagram, we identified 13 stars that could possibly have intrinsic polarization and/or rotation in their polarization angles. One star, 2MASS J06075075+1934177, which is a B4Ve spectral type, shows diffuse interstellar bands in the spectrum in addition to the Hα line in emission. There is an indication for slightly bigger dust grains toward L1570 on the basis of the dust grain size-indicators such as λmax and RV values. The magnetic field lines are found to be parallel to the cloud structures seen in the 250 μm images (also in the 8 μm and 12 μm shadow images) of L1570. Based on the magnetic field geometry, the cloud structure, and the complex velocity structure, we conclude that L1570 is in the process of formation due to the converging flow

  18. 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

  19. 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

  20. Radiative and microphysical properties of cirrus cloud inferred from the MODIS infrared split-window measurements

    NASA Astrophysics Data System (ADS)

    Iwabuchi, H.; Yamada, S.; Katagiri, S.; Yang, P.; Okamoto, H.

    2013-12-01

    An optimal estimation-based algorithm is developed for retrieval of radiative and microphysical properties of cirrus cloud from the measurements made by the Moderate Resolution Imaging Spectroradiometer (MODIS) at three infrared (IR) split-window bands with center wavelengths at 8.5, 11 and 12 μm. Prior information of cloud top and underlying surface temperatures are from the MODIS operational products. A fast forward model is based on semi-analytical equations for the brightness temperature assuming a single-layer homogeneous ice cloud with prescribed particle habit and size distributions. Modeling errors in the brightness temperature from the present approximate treatment of radiative transfer are insignificant, but relatively more substantial errors occur due to the uncertainties in model parameters including surface emissivity, precipitable water, and cloud bottom temperature. The total measurement-model errors are well correlated for the three bands, which is considered properly in the optimal estimation framework. Retrieval errors of cloud optical thickness and effective particle radius are mainly from uncertainties in a priori cloud top and surface temperatures and model parameters. The three-band IR method is suitable for retrieving optical thickness and effective particle radius for opaque and moderately thick cirrus clouds (with cloud optical thicknesses within a range of 0.5-6). The efficient retrieval algorithm enables global-scale remote sensing at a 1-km2 resolution. A tropical region case study demonstrates advantages of the method; particularly, the ability to be applied to more pixels in optically-thin cirrus in comparison with a solar-reflection based method, and the ability of the optimal estimation framework to produce useful diagnostics of retrieval uncertainties and the retrieval cost that denote the quantitative consistency between measurement and model calculation with several assumptions. The IR retrieval shows smaller optical thickness

  1. Atmospheric parameterization schemes for satellite cloud property retrieval during FIRE IFO 2

    NASA Technical Reports Server (NTRS)

    Titlow, James; Baum, Bryan A.

    1993-01-01

    Satellite cloud retrieval algorithms generally require atmospheric temperature and humidity profiles to determine such cloud properties as pressure and height. For instance, the CO2 slicing technique called the ratio method requires the calculation of theoretical upwelling radiances both at the surface and a prescribed number (40) of atmospheric levels. This technique has been applied to data from, for example, the High Resolution Infrared Radiometer Sounder (HIRS/2, henceforth HIRS) flown aboard the NOAA series of polar orbiting satellites and the High Resolution Interferometer Sounder (HIS). In this particular study, four NOAA-11 HIRS channels in the 15-micron region are used. The ratio method may be applied to various channel combinations to estimate cloud top heights using channels in the 15-mu m region. Presently, the multispectral, multiresolution (MSMR) scheme uses 4 HIRS channel combination estimates for mid- to high-level cloud pressure retrieval and Advanced Very High Resolution Radiometer (AVHRR) data for low-level (is greater than 700 mb) cloud level retrieval. In order to determine theoretical upwelling radiances, atmospheric temperature and water vapor profiles must be provided as well as profiles of other radiatively important gas absorber constituents such as CO2, O3, and CH4. The assumed temperature and humidity profiles have a large effect on transmittance and radiance profiles, which in turn are used with HIRS data to calculate cloud pressure, and thus cloud height and temperature. For large spatial scale satellite data analysis, atmospheric parameterization schemes for cloud retrieval algorithms are usually based on a gridded product such as that provided by the European Center for Medium Range Weather Forecasting (ECMWF) or the National Meteorological Center (NMC). These global, gridded products prescribe temperature and humidity profiles for a limited number of pressure levels (up to 14) in a vertical atmospheric column. The FIRE IFO 2

  2. The origin of midlatitude ice clouds and the resulting influence on their microphysical properties

    NASA Astrophysics Data System (ADS)

    Luebke, Anna; Rolf, Christian; Costa, Anja; Afchine, Armin; Avallone, Linnea; Borrmann, Stephan; Baumgardner, Darrel; Klingebiel, Marcus; Kraemer, Martina

    2015-04-01

    Ice clouds are known to play an important role in the radiative balance of the atmosphere. The nature of this role is determined by the macrophysical and microphysical properties of a cloud. Thus, it is crucial that we have an accurate understanding of properties such as the ice water content (IWC), ice crystal concentration (Ni), and ice crystal size (Ri). However, these properties are difficult to parameterize due to their large variability and the fact that they are influenced by a number of other factors such as temperature, vertical velocity, relative humidity with respect to ice (RHice), and the available ice nuclei. The combination of those factors ultimately establishes whether heterogeneous or homogeneous nucleation will lead to ice crystal formation. The aforementioned factors are largely determined by the dynamics of the environment in which the ice cloud forms, collectively contained in a meteorological situation. Ice clouds have been observed in a variety of situations such as frontal systems, jet streams, gravity waves, and convective systems. Most recently, the concept of the influence of large-scale dynamics on midlatitude cirrus properties has been demonstrated in the work of Muehlbauer et al. (2014). In the work presented here, we explore this concept further by examining how differences in dynamics are translated into the differences in IWC, Ni, and Ri that are found within and between datasets. Data from two American-based campaigns, the 2004 Midlatitude Cirrus Experiment (MidCiX) and the 2011 Midlatitude Airborne Cirrus Properties Experiment (MACPEX), as well as some European-based campaigns, the 2004 and 2006 CIRRUS campaigns, the 2013 AIRTOSS-ICE campaign, and the 2014 ML-CIRRUS campaign are combined to form a large, and more latitudinally comprehensive database of Northern Hemisphere in-situ, midlatitude ice cloud observations. We have divided the data by meteorological situation and explored the differences and similarities between

  3. The effects of small ice crystals on the infrared radiative properties of cirrus clouds

    NASA Technical Reports Server (NTRS)

    Takano, Y.; Liou, K. N.; Asano, S.; Heymsfield, A.; Minnis, P.

    1990-01-01

    The effects of nonspherical small ice crystals on the IR radiative properties of cirrus clouds are investigated utilizing light scattering properties of spheroidal particles. Employing the anomalous diffraction theory for spheres and results from the exact spheroid scattering program, efficient parameterization equations are developed for calculations of the absorption and scattering properties for small ice crystals. Parameterization formulas are developed for large ice crystals employing results computed from the geometric ray-tracing method and the Fraunhofer diffraction theory for hexagonal crystals and spheroids.

  4. The footprints of 16 year trends of Arctic springtime cloud and radiation properties on September sea ice retreat

    NASA Astrophysics Data System (ADS)

    Huang, Yiyi; Dong, Xiquan; Xi, Baike; Dolinar, Erica K.; Stanfield, Ryan E.

    2017-02-01

    The most prominent September Arctic sea ice decline over the period of 2000-2015 occurs over the Siberian Sea, Laptev Sea, and Kara Sea. The satellite observed and retrieved sea ice concentration (SIC) and cloud/radiation properties over the Arctic (70°-90°N) have been used to investigate the impact of springtime cloud and radiation properties on September SIC variation. Positive trends of cloud fractions, cloud water paths, and surface downward longwave flux at the surface over the September sea ice retreat areas are found over the period of 1 March to 14 May, while negative trends are found over the period of 15 May to 28 June. The spatial distributions of correlations between springtime cloud/radiation properties and September SIC have been calculated, indicating that increasing cloud fractions and downward longwave flux during springtime tend to enhance sea ice melting due to strong cloud warming effect. Surface downward and upward shortwave fluxes play an important role from May to June when the onset of sea ice melting occurs. The comparison between linearly detrended and nondetrended of each parameter indicates that significant impact of cloud and radiation properties on September sea ice retreat occurs over the Chukchi/Beaufort Sea at interannual time scale, especially over the period of 31 March to 29 April, while strongest climatological trends are found over the Laptev/Siberian Sea.

  5. Airborne validation of cirrus cloud properties derived from CALIPSO lidar measurements: Optical properties

    NASA Astrophysics Data System (ADS)

    Hlavka, Dennis L.; Yorks, John E.; Young, Stuart A.; Vaughan, Mark A.; Kuehn, Ralph E.; McGill, Matthew J.; Rodier, Sharon D.

    2012-05-01

    The Cloud-Aerosol Lidar Infrared Pathfinder Satellite Observations (CALIPSO) satellite was successfully launched in April 2006 to study cloud and aerosol layers using range-resolved laser remote sensing. Dedicated flights were conducted from July 26 to August 14, 2006 using the airborne Cloud Physics Lidar (CPL) to validate the CALIPSO lidar (CALIOP) data products. This paper presents results from coincident ice cloud measurements of lidar ratio, extinction coefficient, and optical depth. Flight segment case studies are shown as well as statistics for all coincident measurements during this CALIPSO-CloudSat Validation Experiment (CC-VEX). For the penetrated portion of opaque layers, CALIOP estimates of lidar ratio and extinction are substantially lower than the corresponding CPL values. Significant differences were also found for measurements of horizontally aligned ice, where different instrument viewing geometries precluded meaningful comparisons. After filtering the data set to exclude these discrepancies, overall CALIOP lidar ratio and extinction averages compared favorably to within 1% of overall CPL averages. When restricting the data further to exact coincident in-cloud point-pairs, CALIOP lidar ratios remained close to CPL values, averaging 2.1% below CPL, and the retrieved extinction and optical depth averaged 14.7% above CPL values, a result partially of higher average CALIOP attenuated backscatter but still a respectably close match.

  6. Studying the influence of temperature and pressure on microphysical properties of mixed-phase clouds using airborne measurements

    NASA Astrophysics Data System (ADS)

    Andreea, Boscornea; Sabina, Stefan; Sorin-Nicolae, Vajaiac; Mihai, Cimpuieru

    2015-04-01

    One cloud type for which the formation and evolution process is not well-understood is the mixed-phase type. In general mixed-phase clouds consist of liquid droplets and ice crystals. The temperature interval within both liquid droplets and ice crystals can potentially coexist is limited to 0 °C and - 40 °C. Mixed-phase clouds account for 20% to 30% of the global cloud coverage. The need to understand the microphysical characteristics of mixed-phase clouds to improve numerical forecast modeling and radiative transfer calculation is of major interest in the atmospheric community. In the past, studies of cloud phase composition have been significantly limited by a lack of aircraft instruments capable of discriminating between the ice and liquid phase for a wide range of particle sizes. Presently, in situ airborne measurements provide the most accurate information about cloud microphysical characteristics. This information can be used for verification of both numerical models and cloud remote-sensing techniques. The knowledge of the temperature and pressure variation during the airborne measurements is crucial in order to understand their influence on the cloud dynamics and also their role in the cloud formation processes like accretion and coalescence. Therefore, in this paper is presented a comprehensive study of cloud microphysical properties in mixed-phase clouds in focus of the influence of temperature and pressure variation on both, cloud dynamics and the cloud formation processes, using measurements performed with the ATMOSLAB - Airborne Laboratory for Environmental Atmospheric Research in property of the National Institute for Aerospace Research "Elie Carafoli" (INCAS). The airborne laboratory equipped for special research missions is based on a Hawker Beechcraft - King Air C90 GTx aircraft and is equipped with a sensors system CAPS - Cloud, Aerosol and Precipitation Spectrometer (30 bins, 0.51-50 µm) and a HAWKEYE cloud probe. The analyzed data in this

  7. A 3-Year Climatology of Cloud and Radiative Properties Derived from GOES-8 Data Over the Southern Great Plains

    NASA Technical Reports Server (NTRS)

    Khaiyer, M. M.; Rapp, A. D.; Doelling, D. R.; Nordeen, M. L.; Minnis, P.; Smith, W. L., Jr.; Nguyen, L.

    2001-01-01

    While the various instruments maintained at the Atmospheric Radiation Measurement (ARM) Program Southern Great Plains (SGP) Central Facility (CF) provide detailed cloud and radiation measurements for a small area, satellite cloud property retrievals provide a means of examining the large-scale properties of the surrounding region over an extended period of time. Seasonal and inter-annual climatological trends can be analyzed with such a dataset. For this purpose, monthly datasets of cloud and radiative properties from December 1996 through November 1999 over the SGP region have been derived using the layered bispectral threshold method (LBTM). The properties derived include cloud optical depths (ODs), temperatures and albedos, and are produced on two grids of lower (0.5 deg) and higher resolution (0.3 deg) centered on the ARM SGP CF. The extensive time period and high-resolution of the inner grid of this dataset allows for comparison with the suite of instruments located at the ARM CF. In particular, Whole-Sky Imager (WSI) and the Active Remote Sensing of Clouds (ARSCL) cloud products can be compared to the cloud amounts and heights of the LBTM 0.3 deg grid box encompassing the CF site. The WSI provides cloud fraction and the ARSCL computes cloud fraction, base, and top heights using the algorithms by Clothiaux et al. (2001) with a combination of Belfort Laser Ceilometer (BLC), Millimeter Wave Cloud Radar (MMCR), and Micropulse Lidar (MPL) data. This paper summarizes the results of the LBTM analysis for 3 years of GOES-8 data over the SGP and examines the differences between surface and satellite-based estimates of cloud fraction.

  8. Cloud properties and radiative effects of the Asian summer monsoon derived from A-Train data

    NASA Astrophysics Data System (ADS)

    Berry, Elizabeth; Mace, Gerald G.

    2014-08-01

    Using A-Train satellite data, we investigate the distribution of clouds and their microphysical and radiative properties in Southeast Asia during the summer monsoon. We find an approximate balance in the top of the atmosphere (TOA) cloud radiative effect, which is largely due to commonly occurring cirrus layers that warm the atmosphere, and less frequent deep layers, which produce a strong cooling at the surface. The distribution of ice water path (IWP) in these layers, obtained from the 2C-ICE CloudSat data product, is highly skewed with a mean value of 440 g m-2 and a median of 24 g m-2. We evaluate the fraction of the total IWP observed by CloudSat and CALIPSO individually and find that both instruments are necessary for describing the overall IWP statistics and particularly the values that are most important to cirrus radiative impact. In examining how cloud radiative effects at the TOA vary as a function of IWP, we find that cirrus with IWP less than 200 g m-2 produce a net warming in the study region. Weighting the distribution of radiative effect by the frequency of occurrence of IWP values, we determine that cirrus with IWP around 20 g m-2 contribute most to heating at the TOA. We conclude that the mean IWP is a poor diagnostic of radiative impact. We suggest that climate model intercomparisons with data should focus on the median IWP because that statistic is more descriptive of the cirrus that contribute most to the radiative impacts of tropical ice clouds.

  9. Properties of Cold HI Emission Clouds in the Inner-Galaxy ALFA Survey

    NASA Astrophysics Data System (ADS)

    Hughes, James Marcus; Gibson, Steven J.; Noriega-Crespo, Alberto; Newton, Jonathan; Koo, Bon-Chul; Douglas, Kevin A.; Peek, Joshua Eli Goldston; Park, Geumsook; Kang, Ji-hyun; Korpela, Eric J.; Heiles, Carl E.; Dame, Thomas M.

    2017-01-01

    Star formation, a critical process within galaxies, occurs in the coldest, densest interstellar clouds, whose gas and dust content are observed primarily at radio and infrared wavelengths. The formation of molecular hydrogen (H2) from neutral atomic hydrogen (HI) is an essential early step in the condensation of these clouds from the ambient interstellar medium, but it is not yet completely understood, e.g., what is the predominant trigger? Even more troubling, the abundance of H2 may be severely underestimated by standard tracers like CO, implying significant "dark" H2, and the quantity of HI may also be in error if opacity effects are neglected. We have developed an automated method to account for both HI and H2 in cold, diffuse clouds traced by narrow-line HI 21-cm emission in the Arecibo Inner-Galaxy ALFA (I-GALFA) survey. Our algorithm fits narrow (2-5 km/s), isolated HI line profiles to determine their spin temperature, optical depth, and true column density. We then estimate the "visible" H2 column in the same clouds with CfA and Planck CO data and the total gas column from dust emission measured by Planck, IRAS, and other surveys. Together, these provide constraints on the dark H2 abundance, which we examine in relation to other cloud properties and stages of development. Our aim is to build a database of H2-forming regions with significant dark gas to aid future analyses of coalescing interstellar clouds. We acknowledge support from NSF, NASA, Western Kentucky University, and Williams College. I-GALFA is a GALFA-HI survey observed with the 7-beam ALFA receiver on the 305-meter William E. Gordon Telescope. The Arecibo Observatory is a U.S. National Science Foundation facility operated under sequential cooperative agreements with Cornell University and SRI International, the latter in alliance with the Ana G. Mendez-Universidad Metropolitana and the Universities Space Research Association.

  10. Meteorology: dusty ice clouds over Alaska.

    PubMed

    Sassen, Kenneth

    2005-03-24

    Particles lofted into the atmosphere by desert dust storms can disperse widely and affect climate directly through aerosol scattering and absorption. They can also affect it indirectly by changing the scattering properties of clouds and, because desert dusts are particularly active ice-forming agents, by affecting the formation and thermodynamic phase of clouds. Here I show that dust storms that occurred in Asia early in 2004 created unusual ice clouds over Alaska at temperatures far warmer than those expected for normal cirrus-cloud formation.

  11. The properties of mid- to far- infrared emission in the Large Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Sakon, Itsuki; Onaka, Takashi; Kaneda, Hidehiro; Tokura, Daisuke; Tajiri, Yuka Y.; Takahashi, Hidenori; Kato, Daisuke; Onishi, Toshikazu

    similar to the Milky way, suggesting the lack of the smaller VSGs (see Figure 2). Next we examine the IRAS colors in the LMC and find that the "linearly rising component" in the plots of excess emission relative to the total far-infrared emission against the dust temperature seen in our Galactic plane (Sakon et al. 2004) also exists in the LMC data and corresponds to the data around young stellar clusters. At the same time, we recognize that the "horizontally spreading component" in the same plots corresponds to the data in general regions of the LMC other than those around young star clusters. These bimodal sequences can be explained by the temperature range of dust which we see at once in the line of sight; the range of dust temperature we see at once is greatly affected whether young star clusters are included or not. We have also investigated the properties of PAHs and VSGs in CO molecular clouds, in which we find that the color of 12μm to 25μm is typically large. This characteristic may be attributed to the shielding of UV radiation fields in dense molecular clouds.

  12. Remote Sensing of Cloud, Aerosol, and Land Properties from MODIS: Applications to the East Asia Region

    NASA Technical Reports Server (NTRS)

    King, Michael D.; Platnick, Steven; Chu, D. Allen; Moody, Eric G.

    2001-01-01

    MODIS is an earth-viewing cross-track scanning spectroradiometer launched on the Terra satellite in December 1999. MODIS scans a swath width sufficient to provide nearly complete global coverage every two days from a polar-orbiting, sun-synchronous platform at an altitude of 705 km, and provides images in 36 spectral bands between 0.415 and 14.235 microns with spatial resolutions of 250 m (two bands), 500 m (five bands) and 1000 m (29 bands). These bands have been carefully selected to enable advanced studies of land, ocean, and atmospheric processes. In this presentation we review the comprehensive set of remote sensing algorithms that have been developed for the remote sensing of atmospheric properties using MODIS data, placing primary emphasis on the principal atmospheric applications of (i) developing a cloud mask for distinguishing clear sky from clouds, (ii) retrieving global cloud radiative and microphysical properties, including cloud top pressure and temperature, effective emissivity, cloud optical thickness, thermodynamic phase, and effective radius, (iii) monitoring tropospheric aerosol optical thickness over the land and ocean and aerosol size distribution over the ocean, (iv) determining atmospheric profiles of moisture and temperature, and (v) estimating column water amount. The physical principles behind the determination of each of these atmospheric products will be described, together with an example of their application using MODIS observations to the east Asian region in Spring 2001. All products are archived into two categories: pixel-level retrievals (referred to as Level-2 products) and global gridded products at a latitude and longitude resolution of 1 degree (Level-3 products). An overview of the MODIS atmosphere algorithms and products, status, validation activities, and early level-2 and -3 results will be presented.

  13. Remote Sensing of Cloud, Aerosol, and Water Vapor Properties from MODIS

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

    MODIS is an earth-viewing cross-track scanning spectroradiometer launched on the Terra satellite in December 1999. MODIS scans a swath width sufficient to provide nearly complete global coverage every two days from a polar orbiting, sun-synchronous, platform at an altitude of 705 kilometers, and provides images in 36 spectral bands between 0.415 and 14.235 micrometers with spatial resolutions of 250 meters (2 bands), 500 meters (5 bands) and 1000 meters (29 bands). These bands have been carefully selected to enable advanced studies of land, ocean, and atmospheric processes. In this presentation we review the comprehensive set of remote sensing algorithms that have been developed for the remote sensing of atmospheric properties using MODIS data, placing primary emphasis on the principal atmospheric applications of (i) developing a cloud mask for distinguishing clear sky from clouds, (ii) retrieving global cloud radiative and microphysical properties, including cloud top pressure and temperature, effective emissivity, cloud optical thickness, thermodynamic phase, and effective radius, (iii) monitoring tropospheric aerosol optical thickness over the land and ocean and aerosol size distribution over the ocean, (iv) determining atmospheric profiles of moisture and temperature, and (v) estimating column water amount. The physical principles behind the determination of each of these atmospheric products will be described, together with an example of their application using MODIS observations. All products are archived into two categories: pixel-level retrievals (referred to as Level-2 products) and global gridded products at a latitude and longitude resolution of 1 degree (Level-3 products). An overview of the MODIS atmosphere algorithms and products, status, validation activities, and early level-2 and -3 results will be presented.

  14. 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.

  15. 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.

  16. Ground based in situ measurements of arctic cloud microphysical and optical properties at Mount Zeppelin (Ny-Alesund Svalbard)

    NASA Astrophysics Data System (ADS)

    Guyot, Gwennolé; Jourdan, Olivier; Olofson, Frans; Schwarzenboeck, Alfons; Gourbeyre, Christophe; Febvre, Guy; Dupuy, Régis; Bernard, Christophe; Tunved, Peter; Ancellet, Gérard; Law, Kathy; Wobrock, Wolfram; Shcherbakov, Valery

    2015-04-01

    The high sensitivity of the polar regions to climate perturbation, due to complex feedback mechanisms existing in this region, was shown by many studies (Solomon et al., 2007; Verlinde et al., 2007; IPCC, 2007). In particular, climate simulations suggest that cloud feedback plays an important role in the arctic warming (Vavrus 2004; Hassol, 2005). Moreover, the high seasonal variability of arctic aerosol properties (Engwall et al., 2008; Tunveld et al., 2013) is expected to significantly impact the cloud properties during the winter-summer transition. Field measurements are needed for improved understanding and representation of cloud-aerosol interactions in climate models. Within the CLIMSLIP project (CLimate IMpacts of Short-LIved Pollutants and methane in the arctic), a two months (March-April 2012) ground-based cloud measurement campaign was performed at Mt Zeppelin station, Ny-Alesund, Svalbard. The experimental set-up comprised a wide variety of instruments. A CPI (Cloud Particle Imager) was used for the microphysical and morphological characterization of ice particles. Measurements of sized-resolved liquid cloud parameters were performed by the FSSP-100 (Forward Scattering Spectrometer Probe). The Nevzorov Probe measured the bulk properties (LWC and IWC) of clouds. The Polar Nephelometer (PN) was used to assess the single scattering properties of an ensemble of cloud particles. This cloud instrumentation combined with the aerosol properties (size distribution and total concentration) continuously measured at the station allowed us to study the variability of the microphysical and optical properties of low level Mixed Phase Clouds (MPC) as well as the aerosol-cloud interaction in the Arctic. Typical properties of MPC, snow precipitation and blowing snow will be presented. First results suggest that liquid water is ubiquitous in arctic low level clouds. Precipitations are characterized by large (typically 1 mm sized) stellar and pristine shape particles

  17. Correlations among the Optical Properties of Cirrus-Cloud Particles: Microphysical Interpretation

    NASA Technical Reports Server (NTRS)

    Reichardt, J.; Reichardt, S.; Hess, M.; McGee, T. J.; Bhartia, P. K. (Technical Monitor)

    2002-01-01

    Cirrus measurements obtained with a ground-based polarization Raman lidar at 67.9 deg N in January 1997 reveal a strong positive correlation between the particle optical properties, specifically depolarization ratio delta(sub par) and extinction- to-backscatter (lidar) ratio S, for delta(sub par) less than approximately 40%, and an anti-correlation for delta(sub par) greater than approximately 40%. Over the length of the measurements the particle properties vary systematically. Initially, delta (sub par) approximately equals 60% and S approximately equals 10sr are observed. Then, with decreasing delta(sub par), S first increases to approximately 27sr (delta(sub par) approximately equals 40%) before decreasing to values around 10sr again (delta(sub par) approximately equals 20%). The analysis of lidar humidity and radiosonde temperature data shows that the measured optical properties stem from scattering by dry solid ice particles, while scattering by supercooled droplets, or by wetted or subliming ice particles can be excluded. For the microphysical interpretation of the lidar measurements, ray-tracing computations of particle scattering properties have been used. The comparison with the theoretical data suggests that the observed cirrus data can be interpreted in terms of size, shape, and, under the assumption that the lidar measurements of consecutive cloud segments can be mapped on the temporal development of a single cloud parcel moving along its trajectory, growth of the cirrus particles: Near the cloud top in the early stage of cirrus development, light scattering by nearly isometric particles that have the optical characteristics of hexagonal columns (short, column-like particles) is dominant. Over time the ice particles grow, and as the cloud base height extends to lower altitudes characterized by warmer temperatures they become morphologically diverse. For large S and depolarization values of approximately 40%, the scattering contributions of column- and

  18. Inference of Ice Cloud Properties from High-spectral Resolution Infrared Observations. Appendix 4

    NASA Technical Reports Server (NTRS)

    Huang, Hung-Lung; Yang, Ping; Wei, Heli; Baum, Bryan A.; Hu, Yongxiang; Antonelli, Paolo; Ackerman, Steven A.

    2005-01-01

    The theoretical basis is explored for inferring the microphysical properties of ice crystal from high-spectral resolution infrared observations. A radiative transfer model is employed to simulate spectral radiances to address relevant issues. The extinction and absorption efficiencies of individual ice crystals, assumed as hexagonal columns for large particles and droxtals for small particles, are computed from a combination of the finite- difference time-domain (FDTD) technique and a composite method. The corresponding phase functions are computed from a combination of FDTD and an improved geometric optics method (IGOM). Bulk scattering properties are derived by averaging the single- scattering properties of individual particles for 30 particle size distributions developed from in situ measurements and for additional four analytical Gamma size distributions for small particles. The non-sphericity of ice crystals is shown to have a significant impact on the radiative signatures in the infrared (IR) spectrum; the spherical particle approximation for inferring ice cloud properties may result in an overest&ation of the optical thickness and an inaccurate retrieval of effective particle size. Furthermore, we show that the error associated with the use of the Henyey-Greenstein phase function can be as larger as 1 K in terms of brightness temperature for larger particle effective size at some strong scattering wavenumbers. For small particles, the difference between the two phase functions is much less, with brightness temperatures generally differing by less than 0.4 K. The simulations undertaken in this study show that the slope of the IR brightness temperature spectrum between 790-960/cm is sensitive to the effective particle size. Furthermore, a strong sensitivity of IR brightness temperature to cloud optical thickness is noted within the l050-1250/cm region. Based on this spectral feature, a technique is presented for the simultaneous retrieval of the visible

  19. Ice Cloud Optical and Microphysical Properties from the CALIPSO Imaging Infrared Radiometer

    NASA Astrophysics Data System (ADS)

    Garnier, A.; Pelon, J.; Dubuisson, P.; Yang, P.; Vaughan, M.; Avery, M. A.; Winker, D. M.

    2013-12-01

    We will present cirrus cloud optical and microphysical properties as retrieved from the operational analysis of the Imaging Infrared Radiometer (IIR) data in synergy with the CALIOP lidar co-located observations collected in the framework of the CALIPSO mission. The IIR data provides nighttime and daytime independent retrievals of optical depth and effective diameter, from which the cloud layer ice water path is inferred. The technique takes advantage of the vertical information provided by CALIOP to select suitable scenes and compute effective emissivity and optical depth. Effective diameters are retrieved through microphysical indices defined as the ratio of the effective infrared optical depths in the two pairs of channels 10.6-12.05 μm and 8.65-12.05 μm, and are related to the ice crystal effective diameter and shape through pre-computed Look-Up Tables. Sources of uncertainty are discussed and possible biases are assessed through internal consistency checks. Comparisons of IIR and CALIOP cirrus optical depths show the very good sensitivity of the IIR retrievals, down to 0.05 visible optical depth. It is shown that particle effective diameter and cloud layer ice water path of single-layered cirrus clouds can be retrieved over ocean, land, as well as over low opaque clouds, for thin to dense clouds of visible optical depth ranging between 0.1 and 6 and of ice water path found typically between 1 and 150 g.m-2. Taking advantage of the cloud boundaries simultaneously derived by CALIOP, IIR power law relationships between mean ice water content (IWC, in g.m-3) and mean extinction coefficient (α, in m-1) are established for cloud temperatures between 190 and 233 K. An average global power law relationship IWC = 75. α1.23 is obtained, which compares well with parameterizations derived from in-situ observations at mid-latitude and in the tropics. However, the IWCs reported in our study are lower by about 40% than those derived from the power law relationship used

  20. Physico-chemical properties of cloud drop residual and interstitial particles sampled inside hill capped clouds during a field experiment in Central Europe

    NASA Astrophysics Data System (ADS)

    Mertes, S.; Schneider, J.; Merkel, M.; Roth, A.; Van Pinxteren, D.; Wiedensohler, A.; Herrmann, H.

    2011-12-01

    ) and forward scattering spectrometer probe (FSSP), like liquid water content, effective drop diameter and drop concentration varied between 0.2 - 0.6 g m-3, 4 - 10 μm and 200 - 500 cm-3, respectively. First results from the AMS phase partitioning comparison shows that the activated mass fraction of the inorganic ions (about 0.9) is significantly higher than that of the organic mass (about 0.8). This finding will be discussed in combination with other chemical composition measurements mentioned above, the analysis of cloud water samples, and the microphysical properties of CDR and IP from which the activation diameter in the different cloud events will be inferred. BC phase partitioning was found to be about 0.5. At south-westerly winds a connected flow between a further cloud-free upwind and downwind measurement site is expected (with the mountain station in between), so that in this special meteorological situation the in-cloud aerosol characterization will be correlated with the physic-chemical properties of the ambient aerosol in the inflow and outflow of the clouds.

  1. Impacts of aerosol particles on the microphysical and radiative properties of stratocumulus clouds over the southeast Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Twohy, C. H.; Anderson, J. R.; Toohey, D. W.; Andrejczuk, M.; Adams, A.; Lytle, M.; George, R. C.; Wood, R.; Saide, P.; Spak, S.; Zuidema, P.; Leon, D.

    2013-03-01

    The southeast Pacific Ocean is covered by the world's largest stratocumulus cloud layer, which has a strong impact on ocean temperatures and climate in the region. The effect of anthropogenic sources of aerosol particles on the stratocumulus deck was investigated during the VOCALS field experiment. Aerosol measurements below and above cloud were made with a ultra-high sensitivity aerosol spectrometer and analytical electron microscopy. In addition to more standard in-cloud measurements, droplets were collected and evaporated using a counterflow virtual impactor (CVI), and the non-volatile residual particles were analyzed. Many flights focused on the gradient in cloud properties on an E-W track along 20° S from near the Chilean coast to remote areas offshore. Mean statistics, including their significance, from eight flights and many individual legs were compiled. Consistent with a continental source of cloud condensation nuclei, below-cloud accumulation-mode aerosol and droplet number concentration generally decreased from near shore to offshore. Single particle analysis was used to reveal types and sources of the enhanced particle number that influence droplet concentration. While a variety of particle types were found throughout the region, the dominant particles near shore were partially neutralized sulfates. Modeling and chemical analysis indicated that the predominant source of these particles in the marine boundary layer along 20° S was anthropogenic pollution from central Chilean sources, with copper smelters a relatively small contribution. Cloud droplets were smaller in regions of enhanced particles near shore. However, physically thinner clouds, and not just higher droplet number concentrations from pollution, both contributed to the smaller droplets. Satellite measurements were used to show that cloud albedo was highest 500-1000 km offshore, and actually slightly lower closer to shore due to the generally thinner clouds and lower liquid water paths

  2. How forest fire affects the chemical properties of Andisols

    NASA Astrophysics Data System (ADS)

    Neris, Jonay; Hernández-Moreno, José Manuel; Tejedor, Marisa; Jiménez, Concepción

    2013-04-01

    Forest fires affect soil physical, chemical and mineralogical properties. However, the magnitude of these changes depends on both fire properties, such as the peak temperature reached and duration or depth achieved; and initial soil properties (soil type) as for example soil moisture, organic matter content or soil structure characteristics. Although many works have studied the effects of fire on the chemical properties of different soil types, its effects on Andisols properties have been omitted until now. Taking into account the high susceptibility to drying processes showed by the properties of Andisols affected by land use changes, it could be expected that the fire effects on their chemical properties may differ from those shown by other types of soil. In this study, the main chemical properties in addition to the specific andic properties of burned pine forest Andisols were compared to their unburned control. The chemical properties of ashes found after fire at the soil surface were also studied. The results show a slightly increase in EC and pH after the fire due mainly to the higher content of cations of the soil solution. Ashes derived from the vegetation and soil organic matter consumption by fire could be the main source of these elements in the soils after a fire, as they showed a high cation content. However, the rise in EC and pH is lower than the reported by most authors for other soil types. This behaviour could be related to the higher organic matter content of this soils, even after fire, and the buffering effect of organic compounds on the soil EC and pH changes after the fire. As other authors have shown, a decrease in both the total and active organic content after the fire was also observed as a result of the fire event. The specific andic properties of Andisols were also affected. The P retention of these soils slightly declines as a consequence of fire, while the content of short-range-order products was also modified, but no statistically

  3. Near-Real Time Cloud Properties and Aircraft Icing Indices from GEO and LEO Satellites

    NASA Technical Reports Server (NTRS)

    Minnis, Patrick; Smith, William L., Jr.; Nguyen, Louis; Spangenberg, D. A.; Heck, Patrick W.; Palikonda, Rabindra; Ayers, J. Kirk; Wolff, Cory; Murray, John J.

    2004-01-01

    Imagers on many of the current and future operational meteorological satellites in geostationary Earth orbit (GEO) and lower Earth orbit (LEO) have enough spectral channels to derive cloud microphysical properties useful for a variety of applications. The products include cloud amount, phase, optical depth, temperature, height and pressure, thickness, effective particle size, and ice or liquid water path, shortwave albedo, and outgoing longwave radiation for each imager pixel. Because aircraft icing depends on cloud temperature, droplet size, and liquid water content as well as aircraft variables, it is possible to estimate the potential icing conditions from the cloud phase, temperature, effective droplet size, and liquid water path. A prototype icing index is currently being derived over the contiguous USA in near-real time from Geostationary Operational Environmental Satellite (GOES-10 and 12) data on a half-hourly basis and from NOAA- 16 Advanced Very High Resolution (AVHRR) data when available. Because the threshold-based algorithm is sensitive to small errors and differences in satellite imager and icing is complex process, a new probability based icing diagnosis technique is developed from a limited set of pilot reports. The algorithm produces reasonable patterns of icing probability and intensities when compared with independent model and pilot report data. Methods are discussed for improving the technique for incorporation into operational icing products.

  4. Parameterization of Cloud Optical Properties for a Mixture of Ice Particles for use in Atmospheric Models

    NASA Technical Reports Server (NTRS)

    Chou, Ming-Dah; Lee, Kyu-Tae; Yang, Ping; Lau, William K. M. (Technical Monitor)

    2002-01-01

    Based on the single-scattering optical properties that are pre-computed using an improve geometric optics method, the bulk mass absorption coefficient, single-scattering albedo, and asymmetry factor of ice particles have been parameterized as a function of the mean effective particle size of a mixture of ice habits. The parameterization has been applied to compute fluxes for sample clouds with various particle size distributions and assumed mixtures of particle habits. Compared to the parameterization for a single habit of hexagonal column, the solar heating of clouds computed with the parameterization for a mixture of habits is smaller due to a smaller cosingle-scattering albedo. Whereas the net downward fluxes at the TOA and surface are larger due to a larger asymmetry factor. The maximum difference in the cloud heating rate is approx. 0.2 C per day, which occurs in clouds with an optical thickness greater than 3 and the solar zenith angle less than 45 degrees. Flux difference is less than 10 W per square meters for the optical thickness ranging from 0.6 to 10 and the entire range of the solar zenith angle. The maximum flux difference is approximately 3%, which occurs around an optical thickness of 1 and at high solar zenith angles.

  5. The Coupled Mars Dust and Water Cycles: Understanding How Clouds Affect the Vertical Distribution and Meridional Transport of Dust and Water

    NASA Astrophysics Data System (ADS)

    Kahre, M. A.

    2015-12-01

    The dust and water cycles are crucial to the current Martian climate, and they are coupled through cloud formation. Dust strongly impacts the thermal structure of the atmosphere and thus greatly affects atmospheric circulation, while clouds provide radiative forcing and control the hemispheric exchange of water through the modification of the vertical distributions of water and dust. Recent improvements in the quality and sophistication of both observations and climate models allow for a more comprehensive understanding of how the interaction between the dust and water cycles (through cloud formation) affects the dust and water cycles individually. We focus here on the effects of clouds on the vertical distribution of dust and water, and how those vertical distributions control the net meridional transport of water. For this study, we utilize observations of temperature, dust and water ice from the Mars Climate Sounder (MCS) on the Mars Reconnaissance Orbiter (MRO) combined with the NASA ARC Mars Global Climate Model (MGCM). We demonstrate that the magnitude and nature of the net meridional transport of water between the northern and southern hemispheres during NH summer is sensitive to the vertical structure of the simulated aphelion cloud belt. We further examine how clouds influence the atmospheric thermal structure and thus the vertical structure of the cloud belt. Our goal is to identify and understand the importance of radiative/dynamic feedbacks due to the physical processes involved with cloud formation and evolution on the current climate of Mars.

  6. The Coupled Mars Dust and Water Cycles: Understanding How Clouds Affect the Vertical Distribution and Meridional Transport of Dust and Water.

    NASA Technical Reports Server (NTRS)

    Kahre, M. A.

    2015-01-01

    The dust and water cycles are crucial to the current Martian climate, and they are coupled through cloud formation. Dust strongly impacts the thermal structure of the atmosphere and thus greatly affects atmospheric circulation, while clouds provide radiative forcing and control the hemispheric exchange of water through the modification of the vertical distributions of water and dust. Recent improvements in the quality and sophistication of both observations and climate models allow for a more comprehensive understanding of how the interaction between the dust and water cycles (through cloud formation) affects the dust and water cycles individually. We focus here on the effects of clouds on the vertical distribution of dust and water, and how those vertical distributions control the net meridional transport of water. For this study, we utilize observations of temperature, dust and water ice from the Mars Climate Sounder (MCS) on the Mars Reconnaissance Orbiter (MRO) combined with the NASA ARC Mars Global Climate Model (MGCM). We demonstrate that the magnitude and nature of the net meridional transport of water between the northern and southern hemispheres during NH summer is sensitive to the vertical structure of the simulated aphelion cloud belt. We further examine how clouds influence the atmospheric thermal structure and thus the vertical structure of the cloud belt. Our goal is to identify and understand the importance of radiative/dynamic feedbacks due to the physical processes involved with cloud formation and evolution on the current climate of Mars.

  7. The Effects of an Absorbing Smoke Layer on MODIS Marine Boundary Layer Cloud Optical Property Retrievals and Radiative Forcing

    NASA Technical Reports Server (NTRS)

    Meyer, Kerry; Platnick, Steven

    2012-01-01

    Clouds, aerosols, and their interactions are widely considered to be key uncertainty components in our current understanding of the Earth's atmosphere and radiation budget. The work presented here is focused on the quasi-permanent marine boundary layer . (MBL) clouds off the southern Atlantic coast of Africa and the effects on MODIS cloud optical property retrievals (MOD06) of an overlying absorbing smoke layer. During much of August and September, a persistent smoke layer resides over this region, produced from extensive biomass burning throughout the southern African savanna. The resulting absorption, which increases with decreasing wavelength, potentially introduces biases into the MODIS cloud optical property retrievals of the underlying MBL clouds. This effect is more pronounced in the cloud optical thickness retrievals, which over ocean are derived from the wavelength channel centered near 0.86 micron (effective particle size retrievals are derived from the longer-wavelength near-IR channels at 1.6, 2.1, and 3.7 microns). Here, the spatial distributions of the scalar statistics of both the cloud and aerosol layers are first determined from the CALIOP 5 km layer products. Next, the MOD06 look-up tables (LUTs) are adjusted by inserting an absorbing smoke layer of varying optical thickness over the cloud. Retrievals are subsequently performed for a subset of MODIS pixels collocated with the CALIOP ground track, using smoke optical thickness from the CALIOP 5km aerosol layer product to select the appropriate LUT. The resulting differences in cloud optical property retrievals due to the inclusion of the smoke layer in the LUTs will be examined. In addition, the direct radiative forcing of this smoke layer will be investigated from the perspective of the cloud optical property retrieval differences.

  8. The Properties of Convective Clouds over the Western Pacific and Their Relationship to the Environment of Tropical Cyclones

    DTIC Science & Technology

    2012-09-30

    1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. The Properties of Convective Clouds over the Western...Properties of Convective Clouds over the Western Pacific and Their Relationship to the Environment of Tropical Cyclones 5a. CONTRACT NUMBER 5b. GRANT...here as being cumulus congestus-like), the TC-related PFs are even more concentrated there. In other words, in TC environments, congestus-like (5-10

  9. On the impact of the magnitude of Interstellar pressure on physical properties of Molecular Cloud

    NASA Astrophysics Data System (ADS)

    Anathpindika, S.; Burkert, A.; Kuiper, R.

    2017-01-01

    Recently reported variations in the typical physical properties of Galactic and extra-Galactic molecular clouds (MCs), and in their star-forming ability have been attributed to local variations in the magnitude of interstellar pressure. Inferences from these surveys have called into question two long-standing beliefs : (1) that MCs are Virialised, and (2) they obey the Larson's third law. Here we invoked the framework of cloud-formation via collision between warm gas-flows to examine if these latest observational inferences can be reconciled. To this end we traced the temporal evolution of the gas surface density, the fraction of dense gas, the distribution of gas column density (N-PDF), and the Virial nature of the assembled clouds. We conclude, these physical properties exhibit temporal variation and their respective peak-magnitude also increases in proportion with the magnitude of external pressure, Pext. The velocity dispersion in assembled clouds appears to follow the power-law, σ _{gas}∝ P_{ext}^{0.23}. The power-law tail at higher densities becomes shallower with increasing magnitude of external pressure for Pext/kB ≲ 107 K cm-3; at higher magnitudes such as those typically found in the Galactic CMZ (Pext/kB > 107 K cm-3), the power-law shows significant steepening. While our results are broadly consistent with inferences from various recent observational surveys, it appears, MCs do not exhibit a unique set of properties, but rather a wide variety that can be reconciled with a range of magnitudes of pressure between 104 K cm-3 - 108 K cm-3.

  10. Comparison of Satellite and Aircraft Measurements of Cloud Microphysical Properties in Icing Conditions During ATREC/AIRS-II

    NASA Technical Reports Server (NTRS)

    Nguyen, Louis; Minnis, Patrick; Spangenberg, Douglas A.; Nordeen, Michele L.; Palikonda, Rabindra; Khaiyer, Mandana M.; Gultepe, Ismail; Reehorst, Andrew L.

    2004-01-01

    Satellites are ideal for continuous monitoring of aircraft icing conditions in many situations over extensive areas. The satellite imager data are used to diagnose a number of cloud properties that can be used to develop icing intensity indices. Developing and validating these indices requires comparison with objective "cloud truth" data in addition to conventional pilot reports (PIREPS) of icing conditions. Minnis et al. examined the relationships between PIREPS icing and satellite-derived cloud properties. The Atlantic-THORPEX Regional Campaign (ATReC) and the second Alliance Icing Research Study (AIRS-II) field programs were conducted over the northeastern USA and southeastern Canada during late 2003 and early 2004. The aircraft and surface measurements are concerned primarily with the icing characteristics of clouds and, thus, are ideal for providing some validation information for the satellite remote sensing product. This paper starts the process of comparing cloud properties and icing indices derived from the Geostationary Operational Environmental Satellite (GOES) with the aircraft in situ measurements of several cloud properties during campaigns and some of the The comparisons include cloud phase, particle size, icing intensity, base and top altitudes, temperatures, and liquid water path. The results of this study are crucial for developing a more reliable and objective icing product from satellite data. This icing product, currently being derived from GOES data over the USA, is an important complement to more conventional products based on forecasts, and PIREPS.

  11. Bacterial ice nuclei impact cloud lifetime and radiative properties and reduce atmospheric heat loss in the BRAMS simulation model

    NASA Astrophysics Data System (ADS)

    Costa, Tassio S.; Gonçalves, Fábio L. T.; Yamasoe, Marcia A.; Martins, Jorge A.; Morris, Cindy E.

    2014-08-01

    This study examines the effect of the bacterial species Pseudomonas syringae acting as ice nuclei (IN) on cloud properties to understand its impact on local radiative budget and heating rates. These bacteria may become active IN at temperatures as warm as -2 °C. Numerical simulations were developed using the Brazilian Regional Atmospheric Model System (BRAMS). To investigate the isolated effect of bacterial IN, four scenarios were created considering only homogeneous and bacterial ice nucleation, with 1, 10 and 100 IN per cubic meter of cloud volume and one with no bacteria. Moreover, two other scenarios were generated: the BRAMS default parameterization and its combination with bacterial IN. The model reproduced a strong convective cell over São Paulo on 3 March 2003. Results showed that bacterial IN may change cloud evolution as well as its microphysical properties, which in turn influence cloud radiative properties. For example, the reflected shortwave irradiance over an averaged domain in a scenario considering bacterial IN added to the BRAMS default parameterization was 14% lower than if bacteria were not considered. Heating rates can also be impacted, especially due to differences in cloud lifetime. Results suggest that the omission of bacterial IN in numerical models, including global cloud models, could neglect relevant ice nucleation processes that potentially influence cloud radiative properties.

  12. Cloud radiative forcing sensitivity to Arctic synoptic regimes, surface type, cloud phase and cloud properties during the Fall 2014 Arctic Radiation, IceBridge and Sea-Ice Experiment (ARISE)

    NASA Astrophysics Data System (ADS)

    Segal-Rosenheimer, Michal; Redemann, Jens; Shinozuka, Yohei; Flynn, Connor; LeBanc, Samuel; Schmidt, Sebastian; Song, Shi; Bucholtz, Anthony; Reid, Elizabeth; Anderson, Bruce; Corr, Chelsea; Smith, William L.; Kato, Seiji; Spangenberg, Douglas A.; Hofton, Michelle; Moore, Richard; Winstead, Edward; Thornhill, Lee K.

    2015-04-01

    Surface cloud radiative forcing (CRF) estimates in the Arctic cover a wide range of values when comparing various datasets (e.g. MERRA, CERES), and show high bias when compared to in-situ ground-based flux measurement stations (e.g. in Greenland) [Wenshan and Zender, 2014]. These high variations and biases result from an intricate relationship between the prevailing synoptic regimes, surface types (open ocean versus sea-ice), and cloud properties [e.g. Barton et al., 2012; Bennartz et al., 2013]. To date, analyses are focused on large-scale or inter-annual comparisons [e.g. Barton et al., 2012; Taylor et al., 2014], or on several specific ground-based sites [Shupe et al., 2004; Sedlar et al., 2012]. Nevertheless, smaller scale CRF variations related to the sharp changes in sea-ice cover, cloud type and synoptic regimes in autumn are still not well understood. Here, we are focusing on assessing the CRF sensitivity to a composite variable matrix of atmospheric stability regimes, cloud profiles and properties and surface type changes during the NASA ARISE campaign conducted in the Fall of 2014 during the Arctic sea-ice minimum in the Beaufort Sea. We are interested in answering the following questions: (1) what are the combinations of distinct synoptic regimes, surface types, and cloud properties that result in the lowest or highest simulated CRF values over the Arctic Beaufort Sea during the autumn 2014 sea-ice growth period?, and (2) can we relate these simulated extremes to the observations made during the ARISE campaign? We are using the libRadtran radiative transfer modeling package to calculate the CRF sensitivity matrix, with daily gridded atmospheric profiles input from MERRA re-analysis, cloud fields and properties from CALIPSO, MODIS, AVHRR, daily variations in sea-ice margins from AMSR-2, and complementary airborne measurements collected on the C-130 during the campaign. In performing sensitivity analysis, we examine CRF extremes sorted by atmospheric

  13. The gas properties of the W3 giant molecular cloud: a HARP study

    NASA Astrophysics Data System (ADS)

    Polychroni, D.; Moore, T. J. T.; Allsopp, J.

    2012-06-01

    We present 12CO, 13CO and C18O J= 3 → 2 maps of the W3 giant molecular cloud (GMC) made at the James Clerk Maxwell Telescope. We combine these observations with Five College Radio Astronomy Observatory CO J= 1→0 data to produce the first map of molecular-gas temperatures across a GMC and the most accurate determination of the mass distribution in W3 yet obtained. We measure excitation temperatures in the part of the cloud dominated by triggered star formation (the high-density layer, HDL) of 15-30 K, while in the rest of the cloud, which is relatively unaffected by triggering (low-density layer), the excitation temperature is generally less than 12 K. We identify a temperature gradient in the HDL which we associate with an age sequence in the embedded massive star-forming regions. We measure the mass of the cloud to be 4.4 ± 0.4 × 105 M⊙, in agreement with previous estimates. Existing submillimetre continuum data are used to derive the fraction of gas mass in dense clumps as a function of position in the cloud. This fraction, which we interpret as a clump formation efficiency (CFE), is significantly enhanced across the HDL, probably due to the triggering. Finally, we measure the 3D rms Mach number, ?, as a function of position and find a correlation between ? and the CFE within the HDL only. This correlation is interpreted as due to feedback from the newly formed stars, and a change in its slope between the three main star-forming regions is construed as another evolutionary effect. We conclude that triggering has affected the star formation process in the W3 GMC primarily by creating additional dense structures that can collapse into stars. Any traces of changes in CFE due to additional turbulence have since been overruled by the feedback effects of the star-forming process itself.

  14. Aerosol-cloud interactions in ship tracks using Terra MODIS/MISR

    NASA Astrophysics Data System (ADS)

    Chen, Yi-Chun; Christensen, Matthew W.; Diner, David J.; Garay, Michael J.

    2015-04-01

    Simultaneous ship track observations from Terra Moderate Resolution Imaging Spectroradiometer (MODIS) and Multiangle Imaging Spectroradiometer (MISR) have been compiled to investigate how ship-injected aerosols affect marine warm boundary layer clouds for different cloud types and environmental conditions. By taking advantage of the high spatial resolution multiangle observations available from MISR, we utilized the retrieved cloud albedo, cloud top height, and cloud motion vectors to examine cloud property responses in ship-polluted and nearby unpolluted clouds. The strength of the cloud albedo response to increased aerosol level is primarily dependent on cloud cell structure, dryness of the free troposphere, and boundary layer depth, corroborating a previous study by Chen et al. (2012) where A-Train satellite data were utilized. Under open cell cloud structure the cloud properties are more susceptible to aerosol perturbations as compared to closed cells. Aerosol plumes caused an increase in liquid water amount (+38%), cloud top height (+13%), and cloud albedo (+49%) for open cell clouds, whereas for closed cell clouds, little change in cloud properties was observed. Further capitalizing on MISR's unique capabilities, the MISR cross-track cloud speed was used to derive cloud top divergence. Statistically averaging the results from the identified plume segments to reduce random noise, we found evidence of cloud top divergence in the ship-polluted clouds, whereas the nearby unpolluted clouds showed cloud top convergence, providing observational evidence of a change in local mesoscale circulation associated with enhanced aerosols. Furthermore, open cell polluted clouds revealed stronger cloud top divergence as compared to closed cell clouds, consistent with different dynamical mechanisms driving their responses. These results suggest that detailed cloud responses, classified by cloud type and environmental conditions, must be accounted for in global climate modeling

  15. Case study on microphysical properties of boundary layer mixed-phase cloud observed at Ny-Ålesund, Svalbard: Observed cloud microphysics and calculated optical properties on 9 June 2011

    NASA Astrophysics Data System (ADS)

    Uchiyama, Akihiro; Yamazaki, Akihiro; Shiobara, Masataka; Kobayashi, Hiroshi

    2014-06-01

    Cloud radiation interactions are important in the global climate system. However, an understanding of mixed-phase boundary layer clouds in the Arctic remains poor. During May-June 2011, ground-based in situ measurements were made at Zeppelin Station, operated by the Norwegian Polar Institute (altitude 474 m) in Ny-Ålesund (78.9°N, 11.9°E), Svalbard. The instruments used comprised a Cloud, Aerosol and Precipitation Spectrometer (CAPS), and a Cloud Particle Microscope imager. The CAPS incorporated a Cloud and Aerosol Spectrometer and Cloud Imaging Probe (CIP). During the observation period, clouds associated with cyclonic disturbances and those associated with outbreaks of westerly cold air masses from the sea were observed. Atmospheric temperature during all measurements ranged from 0 to -5 °C. In every case, columns were the major type of ice particle measured by the CAPS-CIP. Cloud microphysical properties were observed continuously on 9 June 2011. Size spectra, liquid/ice water content, and particle effective size changed depending on progress stages. Based on the observed microphysics, optical properties were calculated and investigated. Optical properties were determined mainly by those of liquid water particles, even during periods when the relative contribution of ice particles to total water content was at the maximum. It was confirmed that the wavelength region of 1.6 and 2.2 μm can be used in remote sensing. This study shows that it is possible to measure detailed changes of cloud properties in the Arctic region by using instruments installed at a ground-based mountain station.

  16. Effects of long-range aerosol transport on the microphysical properties of low-level liquid clouds in the Arctic

    NASA Astrophysics Data System (ADS)

    Coopman, Quentin; Garrett, Timothy J.; Riedi, Jérôme; Eckhardt, Sabine; Stohl, Andreas

    2016-04-01

    The properties of low-level liquid clouds in the Arctic can be altered by long-range pollution transport to the region. Satellite, tracer transport model, and meteorological data sets are used here to determine a net aerosol-cloud interaction (ACInet) parameter that expresses the ratio of relative changes in cloud microphysical properties to relative variations in pollution concentrations while accounting for dry or wet scavenging of aerosols en route to the Arctic. For a period between 2008 and 2010, ACInet is calculated as a function of the cloud liquid water path, temperature, altitude, specific humidity, and lower tropospheric stability. For all data, ACInet averages 0.12 ± 0.02 for cloud-droplet effective radius and 0.16 ± 0.02 for cloud optical depth. It increases with specific humidity and lower tropospheric stability and is highest when pollution concentrations are low. Carefully controlling for meteorological conditions we find that the liquid water path of arctic clouds does not respond strongly to aerosols within pollution plumes. Or, not stratifying the data according to meteorological state can lead to artificially exaggerated calculations of the magnitude of the impacts of pollution on arctic clouds.

  17. STORMVEX: The Storm Peak Lab Cloud Property Validation Experiment Science and Operations Plan

    SciTech Connect

    Mace, J; Matrosov, S; Shupe, M; Lawson, P; Hallar, G; McCubbin, I; Marchand, R; Orr, B; Coulter, R; Sedlacek, A; Avallone, L; Long, C

    2010-09-29

    During the Storm Peak Lab Cloud Property Validation Experiment (STORMVEX), a substantial correlative data set of remote sensing observations and direct in situ measurements from fixed and airborne platforms will be created in a winter season, mountainous environment. This will be accomplished by combining mountaintop observations at Storm Peak Laboratory and the airborne National Science Foundation-supported Colorado Airborne Multi-Phase Cloud Study campaign with collocated measurements from the second ARM Mobile Facility (AMF2). We describe in this document the operational plans and motivating science for this experiment, which includes deployment of AMF2 to Steamboat Springs, Colorado. The intensive STORMVEX field phase will begin nominally on 1 November 2010 and extend to approximately early April 2011.

  18. Cloud microphysical and radiative properties measured by combined lidar, radar, and infrared radiometer

    SciTech Connect

    Eberhard, W.L.; Intrieri, J.M.; Chan, K.P.; Feingold, G.

    1995-04-01

    The goal of our research in the Instrument Development Program (IDP) is to provide experimental descriptions of the bulk, microphysical, and radiative parameters of clouds (especially cirrus) and the relationships between these properties, for use in developing and validating climate models. The strategy of the Atmospheric Lidar Division of our laboratory is to develop remote sensing techniques to simultaneously measure important cloud parameters and to apply these new methods and older ones in case studies and statistical investigations. Our division participated with the University of Utah on technique development during the first three years of IDP including field tests locally and at FIRE II. The Atmospheric Radiation Measurement (ARM) Program also helped fund demonstration of new technology at the Atlantic Stratocumulus Transition EXperiment (ASTEX). Our current research under a new, independent grant comprises four tasks, which are summarized.

  19. Roles of Wind Shear at Different Vertical Levels, Part I: Cloud System Organization and Properties

    SciTech Connect

    Chen, Qian; Fan, Jiwen; Hagos, Samson M.; Gustafson, William I.; Berg, Larry K.

    2015-07-07

    Understanding of critical processes that contribute to the organization of mesoscale convective systems is important for accurate weather forecast and climate prediction. In this study, we investigate the effects of wind shear at different vertical levels on the organization and properties of cloud systems using the Weather Research & Forecasting (WRF) model with a spectral-bin microphysical scheme. The sensitivity experiments are performed by increasing wind shear at the lower (0-5 km), middle (5-10 km), upper (> 10 km) and the entire troposphere, respectively, based on a control run for a mesoscale convective system (MCS) with weak wind shear. We find that increasing wind shear at the both lower and middle vertical levels reduces the domain-accumulated precipitation and the occurrence of heavy rain, while increasing wind shear at the upper levels changes little on precipitation. Although increasing wind shear at the lower-levels is favorable for a more organized quasi-line system which leads to enlarged updraft core area, and enhanced updraft velocities and vertical mass fluxes, the precipitation is still reduced by 18.6% compared with the control run due to stronger rain evaporation induced by the low-level wind shear. Strong wind shear in the middle levels only produces a strong super-cell over a narrow area, leading to 67.3% reduction of precipitation over the domain. By increasing wind shear at the upper levels only, the organization of the convection is not changed much, but the increased cloudiness at the upper-levels leads to stronger surface cooling and then stabilizes the atmosphere and weakens the convection. When strong wind shear exists over the entire vertical profile, a deep dry layer (2-9 km) is produced and convection is severely suppressed. There are fewer very-high (cloud top height (CTH) > 15 km) and very-deep (cloud thickness > 15 km) clouds, and the precipitation is only about 11.8% of the control run. The changes in cloud microphysical

  20. Retrievals of Ice Cloud Microphysical Properties of Deep Convective Systems using Radar Measurements

    NASA Astrophysics Data System (ADS)

    Tian, J.; Dong, X.; Xi, B.; Wang, J.; Homeyer, C. R.

    2015-12-01

    This study presents innovative algorithms for retrieving ice cloud microphysical properties of Deep Convective Systems (DCSs) using Next-Generation Radar (NEXRAD) reflectivity and newly derived empirical relationships from aircraft in situ measurements in Wang et al. (2015) during the Midlatitude Continental Convective Clouds Experiment (MC3E). With composite gridded NEXRAD radar reflectivity, four-dimensional (space-time) ice cloud microphysical properties of DCSs are retrieved, which is not possible from either in situ sampling at a single altitude or from vertical pointing radar measurements. For this study, aircraft in situ measurements provide the best-estimated ice cloud microphysical properties for validating the radar retrievals. Two statistical comparisons between retrieved and aircraft in situ measured ice microphysical properties are conducted from six selected cases during MC3E. For the temporal-averaged method, the averaged ice water content (IWC) and median mass diameter (Dm) from aircraft in situ measurements are 0.50 g m-3 and 1.51 mm, while the retrievals from radar reflectivity have negative biases of 0.12 g m-3 (24%) and 0.02 mm (1.3%) with correlations of 0.71 and 0.48, respectively. For the spatial-averaged method, the IWC retrievals are closer to the aircraft results (0.51 vs. 0.47 g m-3) with a positive bias of 8.5%, whereas the Dm retrievals are larger than the aircraft results (1.65 mm vs. 1.51 mm) with a positive bias of 9.3%. The retrieved IWCs decrease from ~0.6 g m-3 at 5 km to ~0.15 g m-3 at 13 km, and Dm values decrease from ~2 mm to ~0.7 mm at the same levels. In general, the aircraft in situ measured IWC and Dm values at each level are within one standard derivation of retrieved properties. Good agreements between microphysical properties measured from aircraft and retrieved from radar reflectivity measurements indicate the reasonable accuracy of our retrievals.

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

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

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

  2. High-resolution Images of Diffuse Neutral Clouds in the Milky Way. I. Observations, Imaging, and Basic Cloud Properties

    NASA Astrophysics Data System (ADS)

    Pidopryhora, Y.; Lockman, Felix J.; Dickey, J. M.; Rupen, M. P.

    2015-08-01

    A set of diffuse interstellar clouds in the inner Galaxy within a few hundred parsecs of the Galactic plane has been observed at an angular resolution of ≈1&farcm0 combining data from the NRAO Green Bank Telescope and the Very Large Array. At the distance of the clouds, the linear resolution ranges from ˜1.9 to ˜2.8 pc. These clouds have been selected to be somewhat outside of the Galactic plane, and thus are not confused with unrelated emission, but in other respects they are a Galactic population. They are located near the tangent points in the inner Galaxy, and thus at a quantifiable distance: 2.3≤slant R≤slant 6.0 kpc from the Galactic Center and -1000≤slant z≤slant +610 pc from the Galactic plane. These are the first images of the diffuse neutral H i clouds that may constitute a considerable fraction of the interstellar medium (ISM). Peak H i column densities lie in the range NH i = 0.8-2.9 × 1020 cm-2. Cloud diameters vary between about 10 and 100 pc, and their H i mass spans the range from less than a hundred to a few thousands M⊙. The clouds show no morphological consistency of any kind, except that their shapes are highly irregular. One cloud may lie within the hot wind from the nucleus of the Galaxy, and some clouds show evidence of two distinct thermal phases as would be expected from equilibrium models of the ISM.

  3. Assimilation of precipitation-affected microwave radiances in a cloud-resolving WRF ensemble data assimilation system

    NASA Astrophysics Data System (ADS)

    Zhang, Sara; Zupanski, Dusanka; Zupanski, Milija; Hou, Arthur; Cheung, Samson

    2010-05-01

    In the last decade the progress in satellite precipitation estimation and the advance in precipitation assimilation techniques proved to have positive impact on the quality of atmospheric analyses and forecasts. Direct assimilation of rain-affected radiances presents new challenge to optimal utilization of satellite precipitation observations. Currently operational and research experiences in using precipitation observations have focused on a global model resolution with prescribed static forecast error statistics, while a high-resolution with cloud-resolving physics and flow-dependent forecast error information are needed for applications such as for downscaling precipitation information from rain-affected radiances and for improving hydrological forecasts. To address some of these challenges, a WRF ensemble data assimilation system (WRF-EDAS) at cloud-resolving scales has been developed jointly by NASA/GSFC and Colorado State University. The high-resolution WRF-EDAS is designed to assimilate precipitation-affected radiances in addition to the NOAA/NCEP operational data stream of in-situ data and clear-sky satellite observations. The ensemble data assimilation technique opens a new pathway to provide dynamically updated background error covariance, and to utilize full nonlinear microphysics and radiative transfer model in precipitation observation operators. The high resolution of nested domain WRF model first guess allows more realistic representation of precipitation distribution in the field of view (FOV) of microwave radiance observations in low and medium range of frequencies. We present experimental results of assimilating AMSR-E microwave radiances in case studies of summer storm events over land. The assimilation of precipitation-affected radiances from multiple channels of AMSR-E has shown positive impact on the downscaled precipitation analysis and short term forecast of microphysical variables. The sensitivity of precipitation analyses to the

  4. Importance of Physico-Chemical Properties of Aerosols in the Formation of Arctic Ice Clouds

    NASA Astrophysics Data System (ADS)

    Keita, S. A.; Girard, E.

    2014-12-01

    Ice clouds play an important role in the Arctic weather and climate system but interactions between aerosols, clouds and radiation are poorly understood. Consequently, it is essential to fully understand their properties and especially their formation process. Extensive measurements from ground-based sites and satellite remote sensing reveal the existence of two Types of Ice Clouds (TICs) in the Arctic during the polar night and early spring. TIC-1 are composed by non-precipitating very small (radar-unseen) ice crystals whereas TIC-2 are detected by both sensors and are characterized by a low concentration of large precipitating ice crystals. It is hypothesized that TIC-2 formation is linked to the acidification of aerosols, which inhibit the ice nucleating properties of ice nuclei (IN). As a result, the IN concentration is reduced in these regions, resulting to a smaller concentration of larger ice crystals. Over the past 10 years, several parameterizations of homogeneous and heterogeneous ice nucleation have been developed to reflect the various physical and chemical properties of aerosols. These parameterizations are derived from laboratory studies on aerosols of different chemical compositions. The parameterizations are also developed according to two main approaches: stochastic (that nucleation is a probabilistic process, which is time dependent) and singular (that nucleation occurs at fixed conditions of temperature and humidity and time-independent). This research aims to better understand the formation process of TICs using a newly-developed ice nucleation parameterizations. For this purpose, we implement some parameterizations (2 approaches) into the Limited Area version of the Global Multiscale Environmental Model (GEM-LAM) and use them to simulate ice clouds observed during the Indirect and Semi-Direct Arctic Cloud (ISDAC) in Alaska. We use both approaches but special attention is focused on the new parameterizations of the singular approach. Simulation

  5. Reanalysis of Uranus' cloud scattering properties from IRTF/SpeX observations using a self-consistent scattering cloud retrieval scheme

    NASA Astrophysics Data System (ADS)

    Irwin, P. G. J.; Tice, D. S.; Fletcher, L. N.; Barstow, J. K.; Teanby, N. A.; Orton, G. S.; Davis, G. R.

    2015-04-01

    We have developed a new retrieval approach to modelling near-infrared spectra of Uranus that represents a significant improvement over previous modelling methods. We reanalysed IRTF/SpeX observations of Uranus observed in 2009 covering the wavelength range 0.8-1.8 μm and reported by Tice et al. (Tice, D.S., Irwin, P.G.J., Fletcher, L.N., Teanby, N.A., Hurley, J., Orton, G.S., Davis, G.R. [2013]. Icarus 223, 684-698). By retrieving the imaginary refractive index spectra of cloud particles we are able to consistently define the real part of the refractive index spectra, through a Kramers-Kronig analysis, and thus determine self-consistent extinction cross-section, single-scattering and phase-function spectra for the clouds and hazes in Uranus' atmosphere. We tested two different cloud-modelling schemes used in conjunction with the temperature/methane profile of Baines et al. (Baines, K.H., Mickelson, M.E., Larson, L.E., Ferguson, D.W. [1995]. Icarus 114, 328-340), a reanalysis of the Voyager-2 radio-occultation observations performed by Sromovsky, Fry and Kim (Sromovsky, L.A., Fry, P.M., Kim, J.H. [2011]. Icarus 215, 292-312), and a recent determination from Spitzer (Orton, G.S., Fletcher, L.N., Moses, J.I., Mainzer, A.K., Hines, D., Hammel, H.B., Martin-Torres, F.J., Burgdorf, M., Merlet, C., Line, M.R. [2014]. Icarus 243, 494-513). We find that both cloud-modelling schemes represent the observed centre-of-disc spectrum of Uranus well, and both require similar cloud scattering properties of the main cloud residing at ∼2 bars. However, a modified version of the Sromovsky, Fry and Kim (2011) model, with revised spectral properties of the lowest cloud layer, fits slightly better at shorter wavelengths and is more consistent with the expected vertical position of Uranus' methane cloud. We find that the bulk of the reflected radiance from Uranus arises from a thick cloud at approximately the 2 bar level, composed of particles that are significantly more absorbing at

  6. Properties of extra-planar H I clouds in the outer part of the Milky Way

    NASA Astrophysics Data System (ADS)

    Dedes, L.; Kalberla, P. W. M.

    2010-01-01

    Context. There is mounting evidence for an extra-planar gas layer around the Milky Way disk, similar to the anomalous H I gas detected in a few other galaxies. As much as 10% of the gas may be in this phase. Aims: We analyze H I clouds located in the disk-halo interface outside the solar circle to probe the properties of the extra-planar H I gas, which is following Galactic rotation. Methods: We use the Leiden/Argentine/Bonn (LAB) 21-cm line survey to search for H I clouds which take part in the rotation of the Galactic plane, but are located above the disk layer. Selected regions are mapped with the Effelsberg 100-m telescope. Two of the H I halo clouds are studied in detail for their small scale structure using the Westerbork Synthesis Radio Telescope (WSRT)[The Westerbork Synthesis Radio Telescope is operated by ASTRON (Netherlands Foundation for Research in Astronomy) with support from the Netherlands Foundation for Scientific Research NWO.] and the NRAO Very Large Array (VLA)[The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.]. Results: Data from the 100 m telescope allow for the parameterization of 25 distinct H I halo clouds at Galactocentric radii 10 kpc clouds have a median temperature of 620 K, column densities of N_HI ~ 1019 cm-2, and most of them are surrounded by an extended envelope of warmer H I gas. Interferometer observations for two selected regions resolve the H I clouds into several arc-minute sized cores. These cores show narrow line widths (FWHM ~ 3 km s-1), they have volume densities of n > 1.3 cm-3, masses up to 24 M⊙, and are on average in pressure equilibrium with the surrounding envelopes. Pressures and densities fall within the expectations from theoretical phase diagrams (P vs. < nh >). The H I cores tend to be unstable if one assumes a thermally bistable medium, but are in better

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

    SciTech Connect

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

    2011-07-06

    The 'Evaluating Global Aerosol Models and Aerosol and Water Vapor Properties Near Clouds' project focused extensively on the analysis and utilization of water vapor and aerosol profiles derived from the ARM Raman lidar at the Southern Great Plains ARM site. A wide range of different tasks were performed during this project, all of which improved quality of the data products derived from the lidar or advanced the understanding of atmospheric processes over the site. These activities included: upgrading the Raman lidar to improve its sensitivity; participating in field experiments to validate the lidar aerosol and water vapor retrievals; using the lidar aerosol profiles to evaluate the accuracy of the vertical distribution of aerosols in global aerosol model simulations; examining the correlation between relative humidity and aerosol extinction, and how these change, due to horizontal distance away from cumulus clouds; inferring boundary layer turbulence structure in convective boundary layers from the high-time-resolution lidar water vapor measurements; retrieving cumulus entrainment rates in boundary layer cumulus clouds; and participating in a field experiment that provided data to help validate both the entrainment rate retrievals and the turbulent profiles derived from lidar observations.

  8. Statistical Properties of Line Centroid Velocity Increments in the rho Ophiuchi Cloud

    NASA Technical Reports Server (NTRS)

    Lis, D. C.; Keene, Jocelyn; Li, Y.; Phillips, T. G.; Pety, J.

    1998-01-01

    We present a comparison of histograms of CO (2-1) line centroid velocity increments in the rho Ophiuchi molecular cloud with those computed for spectra synthesized from a three-dimensional, compressible, but non-starforming and non-gravitating hydrodynamic simulation. Histograms of centroid velocity increments in the rho Ophiuchi cloud show clearly non-Gaussian wings, similar to those found in histograms of velocity increments and derivatives in experimental studies of laboratory and atmospheric flows, as well as numerical simulations of turbulence. The magnitude of these wings increases monotonically with decreasing separation, down to the angular resolution of the data. This behavior is consistent with that found in the phase of the simulation which has most of the properties of incompressible turbulence. The time evolution of the magnitude of the non-Gaussian wings in the histograms of centroid velocity increments in the simulation is consistent with the evolution of the vorticity in the flow. However, we cannot exclude the possibility that the wings are associated with the shock interaction regions. Moreover, in an active starforming region like the rho Ophiuchi cloud, the effects of shocks may be more important than in the simulation. However, being able to identify shock interaction regions in the interstellar medium is also important, since numerical simulations show that vorticity is generated in shock interactions.

  9. Variations in Venus cloud particle properties: A new view of Venus's cloud morphology as observed by Galileo Near-Infrared Mapping Spectrometer

    NASA Technical Reports Server (NTRS)

    Carlson, R. W.; Kamp, L. W.; Baines, K. H.; Pollack, J. B.; Grinspoon, D. H.; Encrenaz, TH.; Drossart, P.; Taylor, F. W.

    1993-01-01

    Using Venus nightside data obtained by the Galileo Near-Infrared Mapping Spectrometer (NIMS), we have studied the correlation of 1.74 and 2.30 micrometer radiation which is transmitted through the clouds. Since the scattering and absorption properties of the cloud particles are different at these two wavelengths, one can distinguish between abundance variations and variations in the properties of the cloud particles themselves. The correlation of intensities shows a clustering of data into five distinct branches. Using radiative transfer calculations, we interpret these branches as regions of distinct but different mixes of Mode 2' and 3 particles. The data and calculations indicate large differences in these modal ratios, the active cloud regions varying in content from nearly pure Mode 2' particles to almost wholly Mode 3. The spatial distribution of these branches shows large scale sizes and both hemispheric symmetries and asymmetries. High-latitude concentrations of large particles are seen in both hemispheres and there is banded structure of small particles seen in both the North and South which may be related. The mean particle size in the Northern Hemisphere is greater than found in the South. If these different branch regions are due to mixing of vertically stratified source regions (e.g. photochemical and condensation source mechanisms), then the mixing must be coherent over very large spatial scales.

  10. Arctic Stratus Cloud Properties and Their Effect on the Surface Radiation Budget: Selected Cases from FIRE ACE

    NASA Technical Reports Server (NTRS)

    Doug, Xiquan; Mace, Gerald G.; Minnis, Patrick; Young, David F.

    2001-01-01

    To study Arctic stratus cloud properties and their effect on the surface radiation balance during the spring transition season, analyses are performed using data taken during three cloudy and two clear days in May 1998 as part of the First ISCCP Regional Experiment (FIRE) Arctic Cloud Experiment (ACE). Radiative transfer models are used in conjunction with surface- and satellite-based measurements to retrieve the layer-averaged microphysical and shortwave radiative properties. The surface-retrieved cloud properties in Cases 1 and 2 agree well with the in situ and satellite retrievals. Discrepancies in Case 3 are due to spatial mismatches between the aircraft and the surface measurements in a highly variable cloud field. Also, the vertical structure in the cloud layer is not fully characterized by the aircraft measurements. Satellite data are critical for understanding some of the observed discrepancies. The satellite-derived particle sizes agree well with the coincident surface retrievals and with the aircraft data when they were collocated. Optical depths derived from visible-channel data over snow backgrounds were overestimated in all three cases, suggesting that methods currently used in satellite cloud climatologies derive optical depths that are too large. Use of a near-infrared channel with a solar infrared channel to simultaneously derive optical depth and particle size appears to alleviate this overestimation problem. Further study of the optical depth retrieval is needed. The surface-based radiometer data reveal that the Arctic stratus clouds produce a net warming of 20 W m(exp -2) in the surface layer during the transition season suggesting that these clouds may accelerate the spring time melting of the ice pack. This surface warming contrasts with the net cooling at the top of the atmosphere (TOA) during the same period. All analysis of the complete FIRE ACE data sets will be valuable for understanding the role of clouds during the entire melting and

  11. Cloud Properties Simulated by a Single-Column Model. Part II: Evaluation of Cumulus Detrainment and Ice-phase Microphysics Using a Cloud Resolving Model

    NASA Technical Reports Server (NTRS)

    Luo, Yali; Krueger, Steven K.; Xu, Kuan-Man

    2005-01-01

    This paper is the second in a series in which kilometer-scale-resolving observations from the Atmospheric Radiation Measurement program and a cloud-resolving model (CRM) are used to evaluate the single-column model (SCM) version of the National Centers for Environmental Prediction Global Forecast System model. Part I demonstrated that kilometer-scale cirrus properties simulated by the SCM significantly differ from the cloud radar observations while the CRM simulation reproduced most of the cirrus properties as revealed by the observations. The present study describes an evaluation, through a comparison with the CRM, of the SCM's representation of detrainment from deep cumulus and ice-phase microphysics in an effort to better understand the findings of Part I. It is found that detrainment occurs too infrequently at a single level at a time in the SCM, although the detrainment rate averaged over the entire simulation period is somewhat comparable to that of the CRM simulation. Relatively too much detrained ice is sublimated when first detrained. Snow falls over too deep of a layer due to the assumption that snow source and sink terms exactly balance within one time step in the SCM. These characteristics in the SCM parameterizations may explain many of the differences in the cirrus properties between the SCM and the observations (or between the SCM and the CRM). A possible improvement for the SCM consists of the inclusion of multiple cumulus cloud types as in the original Arakawa-Schubert scheme, prognostically determining the stratiform cloud fraction and snow mixing ratio. This would allow better representation of the detrainment from deep convection, better coupling of the volume of detrained air with cloud fraction, and better representation of snow field.

  12. Assessment of NASA GISS CMIP5 and Post-CMIP5 Simulated Clouds and TOA Radiation Budgets Using Satellite Observations. Part I: Cloud Fraction and Properties

    NASA Technical Reports Server (NTRS)

    Stanfield, Ryan E.; Dong, Xiquan; Xi, Baike; Kennedy, Aaron; Del Genio, Anthony D.; Minnia, Patrick; Jiang, Jonathan H.

    2014-01-01

    Although many improvements have been made in phase 5 of the Coupled Model Intercomparison Project (CMIP5), clouds remain a significant source of uncertainty in general circulation models (GCMs) because their structural and optical properties are strongly dependent upon interactions between aerosol/cloud microphysics and dynamics that are unresolved in such models. Recent changes to the planetary boundary layer (PBL) turbulence and moist convection parameterizations in the NASA GISS Model E2 atmospheric GCM(post-CMIP5, hereafter P5) have improved cloud simulations significantly compared to its CMIP5 (hereafter C5) predecessor. A study has been performed to evaluate these changes between the P5 and C5 versions of the GCM, both of which used prescribed sea surface temperatures. P5 and C5 simulated cloud fraction (CF), liquid water path (LWP), ice water path (IWP), cloud water path (CWP), precipitable water vapor (PWV), and relative humidity (RH) have been compared to multiple satellite observations including the Clouds and the Earth's Radiant Energy System-Moderate Resolution Imaging Spectroradiometer (CERES-MODIS, hereafter CM), CloudSat- Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO; hereafter CC), Atmospheric Infrared Sounder (AIRS), and Advanced Microwave Scanning Radiometer for Earth Observing System (AMSR-E). Although some improvements are observed in the P5 simulation on a global scale, large improvements have been found over the southern midlatitudes (SMLs), where correlations increased and both bias and root-mean-square error (RMSE) significantly decreased, in relation to the previous C5 simulation, when compared to observations. Changes to the PBL scheme have resulted in improved total column CFs, particularly over the SMLs where marine boundary layer (MBL) CFs have increased by nearly 20% relative to the previous C5 simulation. Globally, the P5 simulated CWPs are 25 gm22 lower than the previous C5 results. The P5 version of the

  13. Emergent properties of patch shapes affect edge permeability to animals.

    PubMed

    Nams, Vilis O

    2011-01-01

    Animal travel between habitat patches affects populations, communities and ecosystems. There are three levels of organization of edge properties, and each of these can affect animals. At the lowest level are the different habitats on each side of an edge, then there is the edge itself, and finally, at the highest level of organization, is the geometry or structure of the edge. This study used computer simulations to (1) find out whether effects of edge shapes on animal behavior can arise as emergent properties solely due to reactions to edges in general, without the animals reacting to the shapes of the edges, and to (2) generate predictions to allow field and experimental studies to test mechanisms of edge shape response. Individual animals were modeled traveling inside a habitat patch that had different kinds of edge shapes (convex, concave and straight). When animals responded edges of patches, this created an emergent property of responding to the shape of the edge. The response was mostly to absolute width of the shapes, and not the narrowness of them. When animals were attracted to edges, then they tended to collect in convexities and disperse from concavities, and the opposite happened when animals avoided edges. Most of the responses occurred within a distance of 40% of the perceptual range from the tip of the shapes. Predictions were produced for directionality at various locations and combinations of treatments, to be used for testing edge behavior mechanisms. These results suggest that edge shapes tend to either concentrate or disperse animals, simply because the animals are either attracted to or avoid edges, with an effect as great as 3 times the normal density. Thus edge shape could affect processes like pollination, seed predation and dispersal and predator abundance.

  14. Assimilation of precipitation-affected microwave radiances in a cloud-resolving WRF ensemble data assimilation system

    NASA Astrophysics Data System (ADS)

    Zhang, S. Q.; Zupanski, M.; Hou, A. Y.; Lin, X.; Cheung, S.

    2010-12-01

    In the last decade the progress in satellite precipitation estimation and the advance in precipitation assimilation techniques proved to have positive impact on the quality of atmospheric analyses and forecasts. Direct assimilation of rain-affected radiances presents new challenge to optimal utilization of satellite precipitation observations in numeric weather and climate predictions. Current operational and research methodologies are generally limited to relatively coarse resolution models and prescribed static error statistics, and commonly require tangent linear model and adjoint model for the highly non-linear cloud and precipitation physics. To address some of these challenges, a WRF ensemble data assimilation system (Goddard-WRF-EDAS) at cloud-resolving scales has been developed jointly by NASA/GSFC and Colorado State University (CSU). The system employs the Weather Research and Forecasting (WRF) model with NASA Goddard microphysics schemes, and the Maximum Likelihood Ensemble Filter (MLEF). Precipitation affected radiances are assimilated with Goddard Satellite Data Simulator Unit (SDSU) as the observation operator. In addition to the boundary forcing constructed from operational global analysis, NCEP operational data stream is also assimilated to ensure realistic representation of dynamic circulation in the regional domains. Using the ensemble assimilation approach, the forecast error-statistics is updated by ensemble forecasts, and information is extracted from precipitation observations along with other types of data to produce dynamically consistent precipitation analyses and forecasts. We present experimental results of assimilating precipitation-affected microwave radiances over land in middle latitudes. The results demonstrate the data impact to the downscaled precipitation short term forecasts and information propagation from precipitation data to dynamic fields. The error statistics of microphysical control variables and their relationship to the

  15. Evaluation of different factors affecting antimicrobial properties of chitosan.

    PubMed

    Hosseinnejad, Mahmoud; Jafari, Seid Mahdi

    2016-04-01

    Chitosan as one of the natural biopolymers with antimicrobial activities could be a good choice to be applied in many areas including pharmaceuticals, foods, cosmetics, chemicals, agricultural crops, etc. There have been many studies in the literature which show this superb polymer is dependent on many factors to display its antimicrobial properties including the environmental conditions such as pH, type of microorganism, and neighbouring components; and its structural conditions such as molecular weight, degree of deacetylation, derivative form, its concentration, and original source. In this review, after a brief explanation of antimicrobial activity of chitosan and its importance, we will discuss the factors affecting the antimicrobial properties of this biopolymer based on recent studies.

  16. Synergy benefit in temperature, humiditiy and cloud property profiling by integrating ground based and satellite measurements

    NASA Astrophysics Data System (ADS)

    Ebell, K.; Orlandi, E.; Hünerbein, A.; Crewell, S.; Löhnert, U.

    2012-12-01

    Accurate, highly vertically resolved temperature, humidity and cloud property profiles are needed for many applications. They are essential for climate monitoring, a better process understanding and the subsequent improvement of parameterizations in numerical weather prediction and climate models. In order to provide such profiles with a high temporal resolution, multiple wavelength active and passive remote sensing techniques available at ground based observatories, e.g. the Atmospheric Radiation Measruement (ARM) Program and Cloudnet facilities, need to be exploited. In particular, the Integrated Profiling Technique (IPT, Löhnert et al., 2008) has been successfully applied to simultaneously derive profiles of temperature, humidity and liquid water by a Bayesian based retrieval using a combination of ground based microwave radiometer, cloud radar and a priori information. Within the project ICOS (Integrating Cloud Observations from Ground and Space - a Way to Combine Time and Space Information), we develop a flexible IPT, which allows for the combination of a variety of ground based measurements from cloud radar, microwave radiometer (MWR) and IR spectrometer as well as satellite based information from the Spinning Enhanced Visible and InfraRed Imager (SEVIRI) onboard of METEOSAT. As ground based observations are mainly sensitive to the lower parts of the troposphere, the satellite measurements provide complementary information and are thus expected to improve the estimates of the thermodynamic and cloud property profiles, i. e. hydrometeor content and effective radius, considerably. In addition to the SEVIRI IR measurements, which are provided with a high repetition time, information from polar orbiting satellites could be included. In paticular, the potential of the Advanced Microwave Sounding Unit-A (AMSU-A) and Microwave Sounding Unit (MHS) in the retrieval is investigated. In order to understand the improvement by integrating the measurements of the above

  17. Remote Sensing of Cloud, Aerosol, and Water Vapor Properties from MODIS

    NASA Technical Reports Server (NTRS)

    King, Michael D.

    2001-01-01

    MODIS is an earth-viewing cross-track scanning spectroradiometer launched on the Terra satellite in December 1999. MODIS scans a swath width sufficient to provide nearly complete global coverage every two days from a polar-orbiting, sun-synchronous, platform at an altitude of 705 km, and provides images in 36 spectral bands from 0.415 to 14.235 microns with spatial resolutions of 250 m (2 bands), 500 m (5 bands) and 1000 m (29 bands). These bands have been carefully selected to enable advanced studies of land, ocean, and atmospheric processes. In this presentation I will review the comprehensive set of remote sensing algorithms that have been developed for the remote sensing of atmospheric properties using MODIS data, placing primary emphasis on the principal atmospheric applications of: (1) developing a cloud mask for distinguishing clear sky from clouds, (2) retrieving global cloud radiative and microphysical properties, including cloud top pressure and temperature, effective emissivity, cloud optical thickness, thermodynamic phase, and effective radius, (3) monitoring tropospheric aerosol optical thickness over the land and ocean and aerosol size distribution over the ocean, (4) determining atmospheric profiles of moisture and temperature, and (5) estimating column water amount. The physical principles behind the determination of each of these atmospheric products will be described, together with an example of their application using MODIS observations. All products are archived into two categories: pixel-level retrievals (referred to as Level-2 products) and global gridded products at a latitude and longitude resolution of 1 deg (Level-3 products). An overview of the MODIS atmosphere algorithms and products, status, validation activities, and early level-2 and -3 results will be presented. Finally, I will present some highlights from the land and ocean algorithms developed for processing global MODIS observations, including: (1) surface reflectance, (2

  18. On the accretion properties of young stellar objects in the L1615/L1616 cometary cloud

    NASA Astrophysics Data System (ADS)

    Biazzo, K.; Alcalá, J. M.; Frasca, A.; Zusi, M.; Getman, F.; Covino, E.; Gandolfi, D.

    2014-12-01

    We present the results of FLAMES/UVES and FLAMES/GIRAFFE spectroscopic observations of 23 low-mass stars in the L1615/L1616 cometary cloud, complemented with FORS2 and VIMOS spectroscopy of 31 additional stars in the same cloud. L1615/L1616 is a cometary cloud in which the star formation was triggered by the impact of massive stars in the Orion OB association. From the measurements of the lithium abundance and radial velocity, we confirm the membership of our sample to the cloud. We use the equivalent widths of the Hα, Hβ, and the He i λ5876, λ6678, λ7065 Å emission lines to calculate the accretion luminosities, Lacc, and the mass accretion rates, Ṁacc. We find in L1615/L1616 a fraction of accreting objects (~30%), which is consistent with the typical fraction of accretors in T associations of similar age (~3 Myr). The mass accretion rate for these stars shows a trend with the mass of the central object similar to that found for other star-forming regions, with a spread at a given mass that depends on the evolutionary model used to derive the stellar mass. Moreover, the behavior of the 2MASS/WISE colors with Ṁacc indicates that strong accretors with log Ṁacc ≳ -8.5 dex show large excesses in the JHKs bands, as in previous studies. We also conclude that the accretion properties of the L1615/L1616 members are similar to those of young stellar objects in T associations, like Lupus. Based on FLAMES (UVES+GIRAFFE) observations collected at the Very Large Telescope (VLT; Paranal, Chile). Program 076.C-0385(A).Tables 3-6 and Appendices are available in electronic form at http://www.aanda.org

  19. Haze and clouds properties of Saturn's 2011 giant vortex retrieved from Cassini VIMS-V data.

    NASA Astrophysics Data System (ADS)

    Oliva, F.; Adriani, A.; Moriconi, M. L.; Liberti, G. L.; d'Aversa, E.

    2014-04-01

    This work is focused on the retrieval of the microphysical and geometrical properties of the clouds and hazes overlying the giant vortex observed in 2011 at Saturn, by the Visual and Infrared Mapping Spectrometer (VIMS) on board of Cassini. The retrieval algorithm is based on the optimal estimation technique [15] and takes advantage of a forward radiative transfer model developed by adapting the LibRadtran code [13] to the atmosphere of Saturn. For each of the retrieved parameters - that are effective radii, top pressures and total number densities for each considered deck - a 2D spatial map has been produced.

  20. Atmospheric Radiation Measurement (ARM) Data from Steamboat Springs, Colorado, for the Storm Peak Laboratory Cloud Property Validation Experiment (STORMVEX)

    DOE Data Explorer

    In October 2010, the initial deployment of the second ARM Mobile Facility (AMF2) took place at Steamboat Springs, Colorado, for the Storm Peak Laboratory Cloud Property Validation Experiment (STORMVEX). The objective of this field campaign was to obtain data about liquid and mixed-phase clouds using AMF2 instruments in conjunction with Storm Peak Laboratory (located at an elevation of 3220 meters on Mt. Werner), a cloud and aerosol research facility operated by the Desert Research Institute. STORMVEX datasets are freely available for viewing and download. Users are asked to register with the ARM Archive; the user's email address is used from that time forward as the login name.

  1. Aerosol-Cloud Interactions in Ship Tracks Using Terra MODIS/MISR

    NASA Astrophysics Data System (ADS)

    Chen, Y. C.; Christensen, M.; Diner, D. J.; Garay, M. J.; Nelson, D. L.

    2014-12-01

    Simultaneous ship track observations from Terra Moderate Resolution Imaging Spectroradiometer (MODIS) and Multi-angle Imaging SpectroRadiometer (MISR) have been compiled to investigate how ship-injected aerosols affect marine warm boundary layer clouds under different cloud types and environmental conditions. Taking advantage of the high spatial resolution multiangle observations uniquely available from MISR, we utilized the retrieved cloud albedo, cloud top height, and cloud motion vectors to examine the cloud property responses in ship-polluted and nearby unpolluted clouds. The strength of cloud albedo response to increased aerosol level is primarily dependent on cloud cell structure, dryness of the free troposphere, and boundary layer depth, corroborating a previous study by Chen et al. (2012) where A-Train satellite data were applied. Under open cell cloud structure, the cloud properties are more susceptible to aerosol perturbations as compared to closed cells. Aerosol plumes caused an increase in liquid water amount (+27%), cloud top height (+11%), and cloud albedo (+40%) for open cell clouds, whereas under closed cell clouds, little changes in cloud properties were observed. Further capitalizing on MISR's unique capabilities, the MISR cross-track cloud speed has been used to derive cloud top divergence. Statistically averaging the results from many plume segments to reduce random noise, we have found that in ship-polluted clouds there is stronger cloud top divergence, and in nearby unpolluted clouds, convergence occurs and leads to downdrafts, providing observational evidence for cloud top entrainment feedback. These results suggest that detailed cloud responses, classified by cloud type and environmental conditions, must be accounted for in global climate modeling studies to reduce uncertainties of aerosol indirect forcing. Reference: Chen, Y.-C. et al. Occurrence of lower cloud albedo in ship tracks, Atmos. Chem. Phys., 12, 8223-8235, doi:10.5194/acp-12

  2. The 27-28 October 1986 FIRE IFO Cirrus Case Study: Cloud Optical Properties Determined by High Spectral Resolution Lidar

    NASA Technical Reports Server (NTRS)

    Grund, C. J.; Eloranta, E. W.

    1996-01-01

    During the First ISCCP Region Experiment (FIRE) cirrus intensive field observation (IFO) the High Spectral Resolution Lidar was operated from a roof top site on the University of Wisconsin-Madison campus. Because the HSRL technique separately measures the molecular and cloud particle backscatter components of the lidar return, the optical thickness is determined independent of particle backscatter. This is accomplished by comparing the known molecular density distribution to the observed decrease in molecular backscatter signal with altitude. The particle to molecular backscatter ratio yields calibrated measurements of backscatter cross sections that can be plotted ro reveal cloud morphology without distortion due to attenuation. Changes in cloud particle size, shape, and phase affect the backscatter to extinction ratio (backscatter-phase function). The HSRL independently measures cloud particle backscatter phase function. This paper presents a quantitative analysis of the HSRL cirrus cloud data acquired over an approximate 33 hour period of continuous near zenith observations. Correlations between small scale wind structure and cirrus cloud morphology have been observed. These correlations can bias the range averaging inherent in wind profiling lidars of modest vertical resolution, leading to increased measurement errors at cirrus altitudes. Extended periods of low intensity backscatter were noted between more strongly organized cirrus cloud activity. Optical thicknesses ranging from 0.01-1.4, backscatter phase functions between 0.02-0.065 sr (exp -1) and backscatter cross sections spanning 4 orders of magnitude were observed. the altitude relationship between cloud top and bottom boundaries and the cloud optical center altitude was dependent on the type of formation observed Cirrus features were observed with characteristic wind drift estimated horizontal sizes of 5-400 km. The clouds frequently exhibited cellular structure with vertical to horizontal dimension

  3. Silicified structures affect leaf optical properties in grasses and sedge.

    PubMed

    Klančnik, Katja; Vogel-Mikuš, Katarina; Gaberščik, Alenka

    2014-01-05

    Silicon (Si) is an important structural element that can accumulate at high concentrations in grasses and sedges, and therefore Si structures might affect the optical properties of the leaves. To better understand the role of Si in light/leaf interactions in species rich in Si, we examined the total Si and silica phytoliths, the biochemical and morphological leaf properties, and the reflectance and transmittance spectra in grasses (Phragmites australis, Phalaris arundinacea, Molinia caerulea, Deschampsia cespitosa) and sedge (Carex elata). We show that these grasses contain >1% phytoliths per dry mass, while the sedge contains only 0.4%. The data reveal the variable leaf structures of these species and significant differences in the amount of Si and phytoliths between developing and mature leaves within each species and between grasses and sedge, with little difference seen among the grass species. Redundancy analysis shows the significant roles of the different near-surface silicified leaf structures (e.g., prickle hairs, cuticle, epidermis), phytoliths and Si contents, which explain the majority of the reflectance and transmittance spectra variability. The amount of explained variance differs between mature and developing leaves. The transmittance spectra are also significantly affected by chlorophyll a content and calcium levels in the leaf tissue.

  4. Observation of the spectrally invariant properties of clouds in cloudy-to-clear transition zones during the MAGIC field campaign

    SciTech Connect

    Yang, Weidong; Marshak, Alexander; McBride, Patrick J.; Chiu, J. Christine; Knyazikhin, Yuri; Schmidt, K. Sebastian; Flynn, Connor; Lewis, Ernie R.; Eloranta, Edwin W.

    2016-08-11

    We use the spectrally invariant method to study the variability of cloud optical thickness τ and droplet effective radius reff in transition zones (between the cloudy and clear sky columns) observed from Solar Spectral Flux Radiometer (SSFR) and Shortwave Array Spectroradiometer-Zenith (SASZe) during the Marine ARM GPCI Investigation of Clouds (MAGIC) field campaign. The measurements from the SSFR and the SASZe are different, however inter-instrument differences of self-normalized measurements (divided by their own spectra at a fixed time) are small. The spectrally invariant method approximates the spectra in the cloud transition zone as a linear combination of definitely clear and cloudy spectra, where the coefficients, slope and intercept, characterize the spectrally invariant properties of the transition zone. Simulation results from the SBDART (Santa Barbara DISORT Atmospheric Radiative Transfer) model demonstrate that (1) the slope of the visible band is positively correlated with the cloud optical thickness τ while the intercept of the near-infrared band has high negative correlation with the cloud drop effective radius reff even without the exact knowledge of τ; (2) the above relations hold for all Solar Zenith Angle (SZA) and for cloud-contaminated skies. In observations using redundant measurements from SSFR and SASZe, we find that during cloudy-to-clear transitions, (a) the slopes of the visible band decrease, and (b) the intercepts of the near-infrared band remain almost constant near cloud edges. The findings in simulations and observations suggest that, while the optical thickness decreases during the cloudy-to-clear transition, the cloud drop effective radius does not change when cloud edges are approached. Furthermore, these results support the hypothesis that inhomogeneous mixing dominates near cloud edges in the studied cases.

  5. Observation of the spectrally invariant properties of clouds in cloudy-to-clear transition zones during the MAGIC field campaign

    DOE PAGES

    Yang, Weidong; Marshak, Alexander; McBride, Patrick J.; ...

    2016-08-11

    We use the spectrally invariant method to study the variability of cloud optical thickness τ and droplet effective radius reff in transition zones (between the cloudy and clear sky columns) observed from Solar Spectral Flux Radiometer (SSFR) and Shortwave Array Spectroradiometer-Zenith (SASZe) during the Marine ARM GPCI Investigation of Clouds (MAGIC) field campaign. The measurements from the SSFR and the SASZe are different, however inter-instrument differences of self-normalized measurements (divided by their own spectra at a fixed time) are small. The spectrally invariant method approximates the spectra in the cloud transition zone as a linear combination of definitely clear andmore » cloudy spectra, where the coefficients, slope and intercept, characterize the spectrally invariant properties of the transition zone. Simulation results from the SBDART (Santa Barbara DISORT Atmospheric Radiative Transfer) model demonstrate that (1) the slope of the visible band is positively correlated with the cloud optical thickness τ while the intercept of the near-infrared band has high negative correlation with the cloud drop effective radius reff even without the exact knowledge of τ; (2) the above relations hold for all Solar Zenith Angle (SZA) and for cloud-contaminated skies. In observations using redundant measurements from SSFR and SASZe, we find that during cloudy-to-clear transitions, (a) the slopes of the visible band decrease, and (b) the intercepts of the near-infrared band remain almost constant near cloud edges. The findings in simulations and observations suggest that, while the optical thickness decreases during the cloudy-to-clear transition, the cloud drop effective radius does not change when cloud edges are approached. Furthermore, these results support the hypothesis that inhomogeneous mixing dominates near cloud edges in the studied cases.« less

  6. Sensitivity of Photolysis Frequencies and Key Tropospheric Oxidants in a Global Model to Cloud Vertical Distributions and Optical Properties

    NASA Technical Reports Server (NTRS)

    Liu, Hongyu; Crawford, James H.; Considine, David B.; Platnick, Steven E.; Norris, Peter M.; Duncan, Bryan N.; Pierce, Robert B.; Chen, Gao; Yantosca, Robert M.

    2008-01-01

    As a follow-up study to our recent assessment of the radiative effects of clouds on tropospheric chemistry, this paper presents an analysis of the sensitivity of such effects to cloud vertical distributions and optical properties in a global 3-D chemical transport model (GEOS4-Chem CTM). GEOS-Chem was driven with a series of meteorological archives (GEOS1-STRAT, GEOS-3 and GEOS-4) generated by the NASA Goddard Earth Observing System data assimilation system, which have significantly different cloud optical depths (CODs) and vertical distributions. Clouds in GEOS1-STRAT and GEOS-3 have more similar vertical distributions while those in GEOS-4 are optically much thinner in the tropical upper troposphere. We find that the radiative impact of clouds on global photolysis frequencies and hydroxyl radical (OH) is more sensitive to the vertical distribution of clouds than to the magnitude of column CODs. Model simulations with each of the three cloud distributions all show that the change in the global burden of O3 due to clouds is less than 5%. Model perturbation experiments with GEOS-3, where the magnitude of 3-D CODs are progressively varied by -100% to 100%, predict only modest changes (<5%) in global mean OH concentrations. J(O1D), J(NO2) and OH concentrations show the strongest sensitivity for small CODs and become insensitive at large CODs due to saturation effects. Caution should be exercised not to use in photochemical models a value for cloud single scattering albedo lower than about 0.999 in order to be consistent with the current knowledge of cloud absorption at the UV wavelength. Our results have important implications for model intercomparisons and climate feedback on tropospheric photochemistry.

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

    SciTech Connect

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

    2013-08-27

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

  8. Observation of the spectrally invariant properties of clouds in cloudy-to-clear transition zones during the MAGIC field campaign

    NASA Astrophysics Data System (ADS)

    Yang, Weidong; Marshak, Alexander; McBride, Patrick J.; Chiu, J. Christine; Knyazikhin, Yuri; Schmidt, K. Sebastian; Flynn, Connor; Lewis, Ernie R.; Eloranta, Edwin W.

    2016-12-01

    We use the spectrally invariant method to study the variability of cloud optical thickness τ and droplet effective radius reff in transition zones (between the cloudy and clear sky columns) observed from Solar Spectral Flux Radiometer (SSFR) and Shortwave Array Spectroradiometer-Zenith (SASZe) during the Marine ARM GPCI Investigation of Clouds (MAGIC) field campaign. The measurements from the SSFR and the SASZe are different, however inter-instrument differences of self-normalized measurements (divided by their own spectra at a fixed time) are small. The spectrally invariant method approximates the spectra in the cloud transition zone as a linear combination of definitely clear and cloudy spectra, where the coefficients, slope and intercept, characterize the spectrally invariant properties of the transition zone. Simulation results from the SBDART (Santa Barbara DISORT Atmospheric Radiative Transfer) model demonstrate that (1) the slope of the visible band is positively correlated with the cloud optical thickness τ while the intercept of the near-infrared band has high negative correlation with the cloud drop effective radius reff even without the exact knowledge of τ; (2) the above relations hold for all Solar Zenith Angle (SZA) and for cloud-contaminated skies. In observations using redundant measurements from SSFR and SASZe, we find that during cloudy-to-clear transitions, (a) the slopes of the visible band decrease, and (b) the intercepts of the near-infrared band remain almost constant near cloud edges. The findings in simulations and observations suggest that, while the optical thickness decreases during the cloudy-to-clear transition, the cloud drop effective radius does not change when cloud edges are approached. These results support the hypothesis that inhomogeneous mixing dominates near cloud edges in the studied cases.

  9. Observation of the Spectrally Invariant Properties of Clouds in Cloudy-to-Clear Transition Zones During the MAGIC Field Campaign

    NASA Technical Reports Server (NTRS)

    Yang, Weidong; Marshak, Alexander; McBride, Patrick; Chiu, J. Christine; Knyazikhin, Yuri; Schmidt, K. Sebastian; Flynn, Connor; Lewis, Ernie R.; Eloranta, Edwin W.

    2016-01-01

    We use the spectrally invariant method to study the variability of cloud optical thickness tau and droplet effective radius r(sub eff) in transition zones (between the cloudy and clear sky columns) observed from Solar Spectral Flux Radiometer (SSFR) and Shortwave Array Spectroradiometer-Zenith (SASZe) during the Marine ARM GPCI Investigation of Clouds (MAGIC) field campaign. The measurements from the SSFR and the SASZe are different, however inter-instrument differences of self-normalized measurements (divided by their own spectra at a fixed time) are small. The spectrally invariant method approximates the spectra in the cloud transition zone as a linear combination of definitely clear and cloudy spectra, where the coefficients, slope and intercept, characterize the spectrally invariant properties of the transition zone. Simulation results from the SBDART (Santa Barbara DISORT Atmospheric Radiative Transfer) model demonstrate that (1) the slope of the visible band is positively correlated with the cloud optical thickness t while the intercept of the near-infrared band has high negative correlation with the cloud drop effective radius r(sub eff)even without the exact knowledge of tau; (2) the above relations hold for all Solar Zenith Angle (SZA) and for cloud-contaminated skies. In observations using redundant measurements from SSFR and SASZe, we find that during cloudy-to-clear transitions, (a) the slopes of the visible band decrease, and (b) the intercepts of the near-infrared band remain almost constant near cloud edges. The findings in simulations and observations suggest that, while the optical thickness decreases during the cloudy-to-clear transition, the cloud drop effective radius does not change when cloud edges are approached. These results support the hypothesis that inhomogeneous mixing dominates near cloud edges in the studied cases.

  10. Observation of the spectrally invariant properties of clouds in cloudy-to-clear transition zones during the MAGIC field campaign

    SciTech Connect

    Yang, Weidong; Marshak, Alexander; McBride, Patrick J.; Chiu, J. Christine; Knyazikhin, Yuri; Schmidt, K. Sebastian; Flynn, Connor; Lewis, Ernie R.; Eloranta, Edwin W.

    2016-12-01

    We use the spectrally invariant method to study the variability of cloud optical thickness τ and droplet effective radius reff in transition zones (between the cloudy and clear sky columns) observed from Solar Spectral Flux Radiometer (SSFR) and Shortwave Array Spectroradiometer-Zenith (SASZe) during the Marine ARM GPCI Investigation of Clouds (MAGIC) field campaign. The measurements from the SSFR and the SASZe are different, however inter-instrument differences of self-normalized measurements (divided by their own spectra at a fixed time) are small. The spectrally invariant method approximates the spectra in the cloud transition zone as a linear combination of definitely clear and cloudy spectra, where the coefficients, slope and intercept, character-ize the spectrally invariant properties of the transition zone. Simulation results from the SBDART (Santa Barbara DISORT Atmospheric Radiative Transfer) model demonstrate that (1) the slope of the visible band is positively correlated with the cloud optical thickness τ while the intercept of the near-infrared band has high negative cor-relation with the cloud drop effective radius reff even without the exact knowledge of τ; (2) the above relations hold for all Solar Zenith Angle (SZA) and for cloud-contaminated skies. In observations using redundant measure-ments from SSFR and SASZe, we find that during cloudy-to-clear transitions, (a) the slopes of the visible band de-crease, and (b) the intercepts of the near-infrared band remain almost constant near cloud edges. The findings in simulations and observations suggest that, while the optical thickness decreases during the cloudy-to-clear transition, the cloud drop effective radius does not change when cloud edges are approached. These results sup-port the hypothesis that inhomogeneous mixing dominates near cloud edges in the studied cases.

  11. Impacts of aerosol particles on the microphysical and radiative properties of stratocumulus clouds over the Southeast Pacific ocean

    NASA Astrophysics Data System (ADS)

    Twohy, C. H.; Anderson, J. R.; Toohey, D. W.; Andrejczuk, M.; Adams, A.; Lytle, M.; George, R. C.; Wood, R.; Saide, P.; Spak, S.; Zuidema, P.; Leon, D.

    2012-08-01

    The Southeast Pacific Ocean is covered by the world's largest stratocumulus cloud layer, which has a strong impact on ocean temperatures and climate in the region. The effect of anthropogenic sources of aerosol particles such as power plants, urban pollution and smelters on the stratocumulus deck was investigated during the VOCALS field experiment. Aerosol measurements below and above cloud were made with a ultra-high sensitivity aerosol spectrometer and analytical electron microscopy. In addition to more standard in-cloud measurements, droplets were collected and evaporated using a counterflow virtual impactor (CVI), and the non-volatile residual particles were analyzed. Many flights focused on the gradient in cloud properties on an E-W track along 20° S from near the Chilean coast to remote areas offshore. Mean statistics from seven flights and many individual legs were compiled. Consistent with a continental source of cloud condensation nuclei, below-cloud accumulation-mode aerosol and droplet number concentration generally decreased from near shore to offshore. Single particle analysis was used to reveal types and sources of the enhanced particle number. While a variety of particle types were found throughout the region, the dominant particles near shore were partially neutralized sulfates. Modeling and chemical analysis indicated that the predominant source of these particles in the marine boundary layer along 20° S was anthropogenic pollution from central Chilean sources, with copper smelters a relatively small contribution. Cloud droplets were more numerous and smaller near shore, and there was less drizzle. Higher droplet number concentration and physically thinner clouds both contributed to the smaller droplets near shore. Satellite measurements were used to show that cloud albedo was highest 500-1000 km offshore, and actually lower closer to shore due to the generally thinner clouds and lower liquid water paths there. Differences in the size

  12. Relationships Between Ice Cloud Properties and Radiative Effects from A-Train Observations and Global Climate Models

    NASA Astrophysics Data System (ADS)

    Berry, B. J.; Mace, G. G.

    2014-12-01

    Using data from the A-Train satellites, we investigate the distribution of clouds and their microphysical and radiative properties in Southeast Asia during the summer monsoon. We find an approximate balance in the top of the atmosphere (TOA) cloud radiative effect, which is largely due to commonly occurring cirrus layers that warm the atmosphere, and less frequent deep layer clouds, which produce a strong cooling at the surface. The distribution of cloud ice water path (IWP) in cirrus layers, obtained from the 2C-ICE CloudSat data product, is highly skewed with a mean value of 170 g m-2 and a median of 16 g m-2. We evaluate the fraction of the total IWP observed by CloudSat and CALIPSO individually and find that both instruments are necessary for describing the overall IWP statistics and particularly the values that are most important to cirrus radiative impact. In examining how cirrus cloud radiative effects at the TOA vary as a function of IWP, we find that cirrus with IWP less than 200 g m-2 produce a net warming. Weighting the distribution of radiative effect by the frequency of occurrence of IWP values, we find that cirrus with IWP around 20 g m-2 contribute most to heating at the TOA. We conclude that the mean IWP is a poor diagnostic of radiative impact. We suggest that climate model intercomparisons with data should focus on the median IWP because that statistic is more descriptive of the cirrus that contribute most to the radiative impacts of tropical ice clouds. Given these findings, we use the A-Train observations to address the issues of IWP occurrence and high cloud forcing in a global climate model (GCM). Our goal is to determine whether the clouds that heat the upper troposphere in the model are the same genre of clouds that heat the upper troposphere in the real atmosphere. First, we define a cloud radiative kernel that's a function of IWP to determine whether the modeled ice clouds produce similar shortwave and longwave radiative effects at the TOA

  13. Jovian clouds and haze

    NASA Astrophysics Data System (ADS)

    West, Robert A.; Baines, Kevin H.; Friedson, A. James; Banfield, Don; Ragent, Boris; Taylor, Fred W.

    Tropospheric clouds: thermochemical equilibrium theory and cloud microphysical theory, condensate cloud microphysics, tropospheric cloud and haze distribution - observations, results from the Galileo probe experiments, Galileo NIMS observations and results, Galileo SSE observations and results, recent analyses of ground-based and HST data; Tropospheric clouds and haze: optical and physical properties: partical composition, particle optical properties, size and shape, chromophores; Stratospheric haze: particle distribution, optical properties, size and shape, particle formation.

  14. Mechanical Properties of Heat Affected Zone of High Strength Steels

    NASA Astrophysics Data System (ADS)

    Sefcikova, K.; Brtnik, T.; Dolejs, J.; Keltamaki, K.; Topilla, R.

    2015-11-01

    High Strength Steels became more popular as a construction material during last decade because of their increased availability and affordability. On the other hand, even though general use of Advanced High Strength Steels (AHSS) is expanding, the wide utilization is limited because of insufficient information about their behaviour in structures. The most widely used technique for joining steels is fusion welding. The welding process has an influence not only on the welded connection but on the area near this connection, the so-called heat affected zone, as well. For that reason it is very important to be able to determine the properties in the heat affected zone (HAZ). This area of investigation is being continuously developed in dependence on significant progress in material production, especially regarding new types of steels available. There are currently several types of AHSS on the world market. Two most widely used processes for AHSS production are Thermo-Mechanically Controlled Processing (TMCP) and Quenching in connection with Tempering. In the presented study, TMCP and QC steels grade S960 were investigated. The study is focused on the changes of strength, ductility, hardness and impact strength in heat affected zone based on the used amount of heat input.

  15. Do Non-Collagenous Proteins Affect Skeletal Mechanical Properties?

    PubMed Central

    Morgan, Stacyann; Poundarik, Atharva A.; Vashishth, Deepak

    2015-01-01

    The remarkable mechanical behavior of bone is attributed to its complex nanocomposite structure that, in addition to mineral and collagen, comprises a variety of non-collagenous matrix proteins or NCPs. Traditionally, NCPs have been studied as signaling molecules in biological processes including bone formation, resorption and turnover. Limited attention has been given to their role in determining the mechanical properties of bone. Recent studies have highlighted that NCPs can indeed be lost or modified with aging, diseases and drug therapies. Homozygous and heterozygous mice models of key NCP provide a useful approach to determine the impact of NCPs on bone morphology as well as matrix quality, and to carry out detailed mechanical analysis for elucidating the pathway by which NCPs can affect the mechanical properties of bone. In this article, we present a systematic analysis of a large cohort of NCPs on bone’s structural and material hierarchy, and identify three principal pathways by which they determine bone’s mechanical properties. These pathways include alterations of bone morphological parameters crucial for bone’s structural competency, bone quality changes in key matrix parameters (mineral and collagen), and a direct role as load bearing structural proteins. PMID:26048282

  16. Lidar Observations of the Optical Properties and 3-Dimensional Structure of Cirrus Clouds

    NASA Technical Reports Server (NTRS)

    Eloranta, E. W.

    1996-01-01

    The scientific research conducted under this grant have been reported in a series of journal articles, dissertations, and conference proceedings. This report consists of a compilation of these publications in the following areas: development and operation of a High Spectral Resolution Lidar, cloud physics and cloud formation, mesoscale observations of cloud phenomena, ground-based and satellite cloud cover observations, impact of volcanic aerosols on cloud formation, visible and infrared radiative relationships as measured by satellites and lidar, and scattering cross sections.

  17. Determination of the chemical properties of residues retained in individual cloud droplets by XRF microprobe at SPring-8

    NASA Astrophysics Data System (ADS)

    Ma, C.-J.; Tohno, S.; Kasahara, M.; Hayakawa, S.

    2004-06-01

    To determine the chemical properties of residue retained in individual cloud droplets is primarily important for the understanding of rainout mechanism and aerosol modification in droplet. The sampling of individual cloud droplets were carried out on the summit of Mt. Taiko located in Tango peninsula, Kyoto prefecture, during Asian dust storm event in March of 2002. XRF microprobe system equipped at SPring-8, BL-37XU was applied to the subsequent quantification analysis of ultra trace elements in residues of individual cloud droplets. It was possible to form the replicas of separated individual cloud droplets on the thin collodion film. The two dimensional XRF maps for the residues in individual cloud droplets were clearly drawn by scanning of micro-beam. Also, XRF spectra of trace elements in residues were well resolved. From the XRF spectra for individual residues, the chemical mixed state of residues could be assumed. The chemical forms of Fe (Fe +++) and Zn (Zn +) could be clearly characterized by their K-edge micro-XANES spectra. By comparison of Z/Si mass ratios of residues in cloud droplets and those of the original sands collected in desert areas in China, the aging of ambient dust particles and their in cloud modification were indirectly assumed.

  18. A 25-month database of stratus cloud properties generated from ground-based measurements at the Atmospheric Radiation Measurement Southern Great Plains Site

    SciTech Connect

    Dong, Xiquan; Minnis, Patrick; Ackerman, Thomas P.; Clothiaux, Eugene E.; Mace, Gerald G.; Long, Charles N.; Liljegren, James C.

    2000-02-27

    A 25-month database of the macrophysical, microphysical, and radiative properties of isolated and overcast low-level stratus clouds has been generated using a newly developed parameterization and surface measurements from the Atmospheric Radiation Measurement central facility in Oklahoma. The database (5-min resolution) includes two parts: measurements and retrievals. The former consist of cloud base and top heights, layer-mean temperature, cloud liquid water path, and solar transmission ratio measured by a ground-based lidar/ceilometer and radar pair, radiosondes, a microwave radiometer, and a standard Eppley precision spectral pyranometer, respectively. The retrievals include the cloud-droplet effective radius and number concentration and broadband shortwave optical depth and cloud and top-of-atmosphere albedos. Stratus without any overlying mid or high-level clouds occurred most frequently during winter and least often during summer. Mean cloud-layer altitudes and geometric thicknesses were higher and greater, respectively, in summer than in winter. Both quantities are positively correlated with the cloud-layer mean temperature. Mean cloud-droplet effective radii range from 8.1 {mu}m in winter to 9.7 {mu}m during summer, while cloud-droplet number concentrations during winter are nearly twice those in summer. Since cloud liquid water paths are almost the same in both seasons, cloud optical depth is higher during the winter, leading to greater cloud albedos and lower cloud transmittances. (c) 2000 American Geophysical Union.

  19. Near-Real Time Satellite-Retrieved Cloud and Surface Properties for Weather and Aviation Safety Applications

    NASA Astrophysics Data System (ADS)

    Minnis, P.; Smith, W., Jr.; Bedka, K. M.; Nguyen, L.; Palikonda, R.; Hong, G.; Trepte, Q.; Chee, T.; Scarino, B. R.; Spangenberg, D.; Sun-Mack, S.; Fleeger, C.; Ayers, J. K.; Chang, F. L.; Heck, P. W.

    2014-12-01

    Cloud properties determined from satellite imager radiances provide a valuable source of information for nowcasting and weather forecasting. In recent years, it has been shown that assimilation of cloud top temperature, optical depth, and total water path can increase the accuracies of weather analyses and forecasts. Aircraft icing conditions can be accurately diagnosed in near-real time (NRT) retrievals of cloud effective particle size, phase, and water path, providing valuable data for pilots. NRT retrievals of surface skin temperature can also be assimilated in numerical weather prediction models to provide more accurate representations of solar heating and longwave cooling at the surface, where convective initiation. These and other applications are being exploited more frequently as the value of NRT cloud data become recognized. At NASA Langley, cloud properties and surface skin temperature are being retrieved in near-real time globally from both geostationary (GEO) and low-earth orbiting (LEO) satellite imagers for weather model assimilation and nowcasting for hazards such as aircraft icing. Cloud data from GEO satellites over North America are disseminated through NCEP, while those data and global LEO and GEO retrievals are disseminated from a Langley website. This paper presents an overview of the various available datasets, provides examples of their application, and discusses the use of the various datasets downstream. Future challenges and areas of improvement are also presented.

  20. Near-Real Time Satellite-Retrieved Cloud and Surface Properties for Weather and Aviation Safety Applications

    NASA Technical Reports Server (NTRS)

    Minnis, Patrick; Smith, William L., Jr.; Bedka, Kristopher M.; Nguyen, Louis; Palikonda, Rabindra; Hong, Gang; Trepte, Qing Z.; Chee, Thad; Scarino, Benjamin; Spangenberg, Douglas A.; Sun-Mack, Szedung; Fleeger, Cecilia; Ayers, J. Kirk; Chang, Fu-Lung; Heck, Patrick M.

    2014-01-01

    Cloud properties determined from satellite imager radiances provide a valuable source of information for nowcasting and weather forecasting. In recent years, it has been shown that assimilation of cloud top temperature, optical depth, and total water path can increase the accuracies of weather analyses and forecasts. Aircraft icing conditions can be accurately diagnosed in near-­-real time (NRT) retrievals of cloud effective particle size, phase, and water path, providing valuable data for pilots. NRT retrievals of surface skin temperature can also be assimilated in numerical weather prediction models to provide more accurate representations of solar heating and longwave cooling at the surface, where convective initiation. These and other applications are being exploited more frequently as the value of NRT cloud data become recognized. At NASA Langley, cloud properties and surface skin temperature are being retrieved in near-­-real time globally from both geostationary (GEO) and low-­-earth orbiting (LEO) satellite imagers for weather model assimilation and nowcasting for hazards such as aircraft icing. Cloud data from GEO satellites over North America are disseminated through NCEP, while those data and global LEO and GEO retrievals are disseminated from a Langley website. This paper presents an overview of the various available datasets, provides examples of their application, and discusses the use of the various datasets downstream. Future challenges and areas of improvement are also presented.

  1. Simulation study of the remote sensing of optical and microphysical properties of cirrus clouds from satellite IR measurements.

    PubMed

    Xu, L; Zhang, J

    1995-05-20

    Improved ray-optics theory and Mie theory for single scattering and an adding-doubling method for multiple scattering have been used to study the interaction of radiation in NASA's Visible and Infrared Spin-Scan Radiometer Atmospheric Sounder Satellite (VAS) IR channels and the microphysics of inhomogeneous cirrus clouds. The simulation study shows that crystal shape has remarkable effects on scattering and on the radiative-transfer properties of cirrus clouds in IR spectra. The sensitivity of the brightness temperature, as observed with VAS-IR channels, to the hexagonal columns and plates in cirrus clouds is noticeable. A method that permits one to infer the optical thickness, crystal shape, ice-water content,and emittance of cirrus clouds by using a multi-IR window channel with a scanning observation technique is developed. Detailed error analyses are carried out, and the characteristics of VAS-IR window channels are investigated through the examination of the effects of sea-surface reflection and variations in the temperature and water-vapor profiles on the VAS measurements. It is shown that these effects are large and need to be considered. Some uncertainties that have risen from the theoretical model are studied; they demonstrate that the Mie-scattering theory should not be used to retrieve the microphysical and optical properties of cirrus clouds. A suitable cloud-microphysics model and a suitable scattering model are needed instead.

  2. Properties of the size-resolved and individual cloud droplets collected in western Japan during the Asian dust storm event

    NASA Astrophysics Data System (ADS)

    Ma, Chang-Jin; Tohno, Susumu; Kasahara, Mikio; Hayakawa, Shinjiro

    With the point of view of the removal mechanism of Asian dust storm particles, in order to study the physiochemical properties of clouds a field campaign was conducted in western Japan during the Asian dust storm event. The polymeric water absorbent film and collodion film replication techniques were employed in the measurements of size-fractionated precipitation cloud and individual cloud droplets, respectively. In addition, to investigate the source profiles of the elements retained in cloud samples, the original desert sand was collected. Particle-induced X-ray emission was applied for the elemental analysis of size-resolved cloud droplets and desert sand. Also for the quantification analysis of the ultra trace elements in residual particles in individual cloud droplets, the X-ray microprobe system equipped at Super Photon ring-8 GeV (SPring-8) BL-37XU was newly applied. Soil derived components like Si, Ca, and Fe show higher mass concentrations in small droplets (<6.4 μm) than in large droplets (>6.4 μm), while S and Cl dominate at droplet size larger than 20 μm. Three cloud samples have liquid water content ranging from 0.04 to 0.11 g m -3. The number size distribution of droplets collected at cloud base is monomodal with the maximum level around 15 μm. The size distribution of cloud droplets is widespread (up to 60 μm). The droplet residues mainly consisting of crustal components were successively reconstructed as elemental maps by the X-ray fluorescence (XRF) microprobe analytical technique. From these XRF elemental maps, it can be understood that crustal components are significantly distributed on and/or in the residual particles in individual cloud droplets. The plotting of enrichment factors calculated from the elemental composition of original desert sand in China not only indicates the good correlationship between elemental masses in residual particles of cloud base droplets and those of precipitation cloud, but also classify elements into soil

  3. Top-of-Atmosphere Albedo Estimation from Angular Distribution Models using Scene Identification from Satellite Cloud Property Retrievals

    NASA Technical Reports Server (NTRS)

    Loeb, N. G.; Parol, F.; Buriez, J.-C.; Vanbauce, C.

    2000-01-01

    The next generation of Earth radiation budget satellite instruments will routinely merge estimates of global top-of-atmosphere radiative fluxes with cloud properties. This information will offer many new opportunities for validating radiative transfer models and cloud parameterizations in climate models. In this study, five months of POLarization and Directionality of the Earth's Reflectances (POLDER) 670 nm radiance measurements are considered in order to examine how satellite cloud property retrievals can be used to define empirical Angular Distribution Models (ADMs) for estimating top-of-atmosphere (TOA) albedo. ADMs are defined for 19 scene types defined by satellite retrievals of cloud fraction and cloud optical depth. Two approaches are used to define the ADM scene types: The first assumes there are no biases in the retrieved cloud properties and defines ADMs for fixed discrete intervals of cloud fraction and cloud optical depth (fixed-tau approach). The second approach involves the same cloud fraction intervals, but uses percentile intervals of cloud optical depth instead (percentile-tau approach). Albedos generated using these methods are compared with albedos inferred directly from the mean observed reflectance field. Albedos based on ADMs that assume cloud properties are unbiased (fixed-tau approach) show a strong systematic dependence on viewing geometry. This dependence becomes more pronounced with increasing solar zenith angle, reaching approximately equals 12% (relative) between near-nadir and oblique viewing zenith angles for solar zenith angles between 60 deg and 70 deg. The cause for this bias is shown to be due to biases in the cloud optical depth retrievals. In contrast, albedos based on ADMs built using percentile intervals of cloud optical depth (percentile-tau approach) show very little viewing zenith angle dependence and are in good agreement with albedos obtained by direct integration of the mean observed reflectance field (less than 1

  4. Optical and geometrical properties of cirrus clouds in Amazonia derived from 1 year of ground-based lidar measurements

    NASA Astrophysics Data System (ADS)

    Gouveia, Diego A.; Barja, Boris; Barbosa, Henrique M. J.; Seifert, Patric; Baars, Holger; Pauliquevis, Theotonio; Artaxo, Paulo

    2017-03-01

    Cirrus clouds cover a large fraction of tropical latitudes and play an important role in Earth's radiation budget. Their optical properties, altitude, vertical and horizontal coverage control their radiative forcing, and hence detailed cirrus measurements at different geographical locations are of utmost importance. Studies reporting cirrus properties over tropical rain forests like the Amazon, however, are scarce. Studies with satellite profilers do not give information on the diurnal cycle, and the satellite imagers do not report on the cloud vertical structure. At the same time, ground-based lidar studies are restricted to a few case studies. In this paper, we derive the first comprehensive statistics of optical and geometrical properties of upper-tropospheric cirrus clouds in Amazonia. We used 1 year (July 2011 to June 2012) of ground-based lidar atmospheric observations north of Manaus, Brazil. This dataset was processed by an automatic cloud detection and optical properties retrieval algorithm. Upper-tropospheric cirrus clouds were observed more frequently than reported previously for tropical regions. The frequency of occurrence was found to be as high as 88 % during the wet season and not lower than 50 % during the dry season. The diurnal cycle shows a minimum around local noon and maximum during late afternoon, associated with the diurnal cycle of precipitation. The mean values of cirrus cloud top and base heights, cloud thickness, and cloud optical depth were 14.3 ± 1.9 (SD) km, 12.9 ± 2.2 km, 1.4 ± 1.1 km, and 0.25 ± 0.46, respectively. Cirrus clouds were found at temperatures down to -90 °C. Frequently cirrus were observed within the tropical tropopause layer (TTL), which are likely associated to slow mesoscale uplifting or to the remnants of overshooting convection. The vertical distribution was not uniform, and thin and subvisible cirrus occurred more frequently closer to the tropopause. The mean lidar ratio was 23.3 ± 8.0 sr. However, for

  5. The Mass Distribution and Assembly of the Milky Way from the Properties of the Magellanic Clouds

    SciTech Connect

    Busha, Michael T.; Marshall, Philip J.; Wechsler, Risa H.; Klypin, Anatoly; Primack, Joel; /UC, Santa Cruz, Phys. Dept.

    2012-02-29

    We present a new measurement of the mass of the Milky Way (MW) based on observed properties of its largest satellite galaxies, the Magellanic Clouds (MCs), and an assumed prior of a {Lambda}CDM universe. The large, high-resolution Bolshoi cosmological simulation of this universe provides a means to statistically sample the dynamical properties of bright satellite galaxies in a large population of dark matter halos. The observed properties of the MCs, including their circular velocity, distance from the center of the MW, and velocity within the MW halo, are used to evaluate the likelihood that a given halo would have each or all of these properties; the posterior probability distribution function (PDF) for any property of the MW system can thus be constructed. This method provides a constraint on the MW virial mass, 1.2{sup +0.7} - {sub 0.4}(stat.){sup +0.3} - {sub 0.3}(sys.) x 10{sup 12} M {circle_dot} (68% confidence), which is consistent with recent determinations that involve very different assumptions. In addition, we calculate the posterior PDF for the density profile of the MW and its satellite accretion history. Although typical satellites of 10{sup 12} M {circle_dot} halos are accreted over a wide range of epochs over the last 10 Gyr, we find a {approx}72% probability that the MCs were accreted within the last Gyr, and a 50% probability that they were accreted together.

  6. THE MASS DISTRIBUTION AND ASSEMBLY OF THE MILKY WAY FROM THE PROPERTIES OF THE MAGELLANIC CLOUDS

    SciTech Connect

    Busha, Michael T.; Marshall, Philip J.; Wechsler, Risa H.; Klypin, Anatoly; Primack, Joel E-mail: pjm@slac.stanford.edu E-mail: aklypin@nmsu.edu

    2011-12-10

    We present a new measurement of the mass of the Milky Way (MW) based on observed properties of its largest satellite galaxies, the Magellanic Clouds (MCs), and an assumed prior of a {Lambda}CDM universe. The large, high-resolution Bolshoi cosmological simulation of this universe provides a means to statistically sample the dynamical properties of bright satellite galaxies in a large population of dark matter halos. The observed properties of the MCs, including their circular velocity, distance from the center of the MW, and velocity within the MW halo, are used to evaluate the likelihood that a given halo would have each or all of these properties; the posterior probability distribution function (PDF) for any property of the MW system can thus be constructed. This method provides a constraint on the MW virial mass, 1.2{sup +0.7}{sub -0.4} (stat.){sup +0.3}{sub -0.3} (sys.) Multiplication-Sign 10{sup 12} M{sub Sun} (68% confidence), which is consistent with recent determinations that involve very different assumptions. In addition, we calculate the posterior PDF for the density profile of the MW and its satellite accretion history. Although typical satellites of 10{sup 12} M{sub Sun} halos are accreted over a wide range of epochs over the last 10 Gyr, we find a {approx}72% probability that the MCs were accreted within the last Gyr, and a 50% probability that they were accreted together.

  7. First results of the AIRS Version 6 cloud top microphysical properties

    NASA Astrophysics Data System (ADS)

    Kahn, B. H.; Irion, F. W.; Manning, E.; Nasiri, S. L.; Jin, H.; Schreier, M. M.; Yue, Q.; Fetzer, E.; Liou, K.

    2012-12-01

    The new cloud products from the upcoming Version 6 release of the Atmospheric Infrared Sounder (AIRS) algorithm is described and initial results are presented. The three new cloud retrieval products include cloud thermodynamic phase, cirrus cloud optical thickness, and cirrus cloud effective diameter. The retrieval methodology of the cirrus cloud parameters is based on an optimal estimation approach that uses observed radiances and cloud clearing-derived atmospheric profiles that define the atmospheric state, surface temperature and emissivity, and cloud top temperature. We will compare the new AIRS retrievals to similar retrievals from the Moderate Resolution Imaging Spectroradiometer (MODIS) and possibly other A-train instruments, and also will demonstrate that the new suite of AIRS cloud products offer useful and tangible constraints for climate model development.

  8. The Roles of Cloud Drop Effective Radius and LWP in Determining Rain Properties in Marine Stratocumulus

    SciTech Connect

    Rosenfeld, Daniel; Wang, Hailong; Rasch, Philip J.

    2012-07-04

    Numerical simulations described in previous studies showed that adding cloud condensation nuclei to marine stratocumulus can prevent their breakup from closed into open cells. Additional analyses of the same simulations show that the suppression of rain is well described in terms of cloud drop effective radius (re). Rain is initiated when re near cloud top is around 12-14 um. Cloud water starts to get depleted when column-maximum rain intensity (Rmax) exceeds 0.1 mm h-1. This happens when cloud-top re reaches 14 um. Rmax is mostly less than 0.1 mm h-1 at re<14 um, regardless of the cloud water path, but increases rapidly when re exceeds 14 um. This is in agreement with recent aircraft observations and theoretical observations in convective clouds so that the mechanism is not limited to describing marine stratocumulus. These results support the hypothesis that the onset of significant precipitation is determined by the number of nucleated cloud drops and the height (H) above cloud base within the cloud that is required for cloud drops to reach re of 14 um. In turn, this can explain the conditions for initiation of significant drizzle and opening of closed cells providing the basis for a simple parameterization for GCMs that unifies the representation of both precipitating and non-precipitating clouds as well as the transition between them. Furthermore, satellite global observations of cloud depth (from base to top), and cloud top re can be used to derive and validate this parameterization.

  9. Aphelion water-ice cloud mapping and property retrieval using the OMEGA imaging spectrometer onboard Mars Express

    NASA Astrophysics Data System (ADS)

    Madeleine, J.-B.; Forget, F.; Spiga, A.; Wolff, M. J.; Montmessin, F.; Vincendon, M.; Jouglet, D.; Gondet, B.; Bibring, J.-P.; Langevin, Y.; Schmitt, B.

    2012-05-01

    Mapping of the aphelion clouds over the Tharsis plateau and retrieval of their particle size and visible opacity are made possible by the OMEGA imaging spectrometer aboard Mars Express. Observations cover the period from MY26 Ls = 330° to MY29 Ls = 180° and are acquired at various local times, ranging from 8 AM to 6 PM. Cloud maps of the Tharsis region constructed using the 3.1 μm ice absorption band reveal the seasonal and diurnal evolution of aphelion clouds. Four distinct types of clouds are identified: morning hazes, topographically controlled hazes, cumulus clouds and thick hazes. The location and time of occurrence of these clouds are analyzed and their respective formation process is discussed. An inverse method for retrieving cloud particle size and opacity is then developed and can only be applied to thick hazes. The relative error of these measurements is less than 30% for cloud particle size and 20% for opacity. Two groups of particles can be distinguished. The first group is found over flat plains and is composed of relatively small particles, ranging in size from 2 to 3.5 μm. The second group is characterized by particle sizes of ˜5 μm which appear to be quite constant over Ls and local time. It is found west of Ascraeus and Pavonis Mons, and near Lunae Planum. These regions are preferentially exposed to anabatic winds, which may control the formation of these particles and explain their distinct properties. The water ice column is equal to 2.9 pr.μm on average, and can reach 5.2 pr.μm in the thickest clouds of Tharsis.

  10. Investigation of the seasonal variations of aerosol physicochemical properties and their impact on cloud condensation nuclei number concentration

    NASA Astrophysics Data System (ADS)

    Logan, Timothy S.

    Aerosols are among the most complex yet widely studied components of the atmosphere not only due to the seasonal variability of their physical and chemical properties but also their effects on climate change. The three main aerosol types that are known to affect the physics and chemistry of the atmosphere are: mineral dust, anthropogenic pollution, and biomass burning aerosols. In order to understand how these aerosols affect the atmosphere, this dissertation addresses the following three scientific questions through a combination of surface and satellite observations: SQ1: What are the seasonal and regional variations of aerosol physico-chemical properties at four selected Asian sites? SQ2: How do these aerosol properties change during transpacific and intra-continental long range transport? SQ3: What are the impacts of aerosol properties on marine boundary layer cloud condensation nuclei number concentration? This dissertation uses an innovative approach to classify aerosol properties by region and season to address SQ1. This is useful because this method provides an additional dimension when investigating the physico-chemical properties of aerosols by linking a regional and seasonal dependence to both the aerosol direct and indirect effects. This method involves isolating the aerosol physico-chemical properties into four separate regions using AERONET retrieved Angstrom exponent (AEAOD) and single scattering co-albedo (o oabs) to denote aerosol size and absorptive properties. The aerosols events are then clustered by season. The method is first applied to four AERONET sites representing single mode aerosol dominant regions: weakly absorbing pollution (NASA Goddard), strongly absorbing pollution (Mexico City), mineral dust (Solar Village), and biomass burning smoke (Alta Floresta). The method is then applied to four Asian sites that represent complicated aerosol components. There are strong regional and seasonal influences of the four aerosol types over the

  11. A Cloud-Resolving Modeling Intercomparison Study on Properties of Cloud Microphysics, Convection, and Precipitation for a Squall Line Cas

    NASA Astrophysics Data System (ADS)

    Fan, J.; Han, B.; Morrison, H.; Varble, A.; Mansell, E.; Milbrandt, J.; Wang, Y.; Lin, Y.; Dong, X.; Giangrande, S. E.; Jensen, M. P.; Collis, S. M.; North, K.; Kollias, P.

    2015-12-01

    The large spread in CRM model simulations of deep convection and aerosol effects on deep convective clouds (DCCs) makes it difficult (1) to further our understanding of deep convection and (2) to define "benchmarks" and recommendations for their use in parameterization developments. Past model intercomparison studies used different models with different complexities of dynamic-microphysics interactions, making it hard to isolate the causes of differences between simulations. In this intercomparison study, we employed a much more constrained approach - with the same model and same experiment setups for simulations with different cloud microphysics schemes (one-moment, two-moment, and bin models). Both the piggybacking and interactive approaches are employed to explore the major microphysical processes that control the model differences and the significance of their feedback to dynamics through latent heating/cooling and cold pool characteristics. Real-case simulations are conducted for the squall line case 20 May 2011 from the MC3E field campaign. Results from the piggybacking approach show substantially different responses of the microphysics schemes to the same dynamical fields. Although the interactive microphysics-dynamics simulations buffer some differences compared with those from the piggyback runs, large differences still exist and are mainly contributed by ice microphysical processes parameterizations. The presentation will include in-depth analyses of the major microphysical processes for the squall line case, the significance of the feedback of the processes to dynamics, and how those results differ in different cloud microphysics schemes.

  12. Validation of GOES-10 Satellite-derived Cloud and Radiative Properties for the MASRAD ARM Mobile Facility Deployment

    NASA Technical Reports Server (NTRS)

    Khaiyer, M. M.; Doelling, D. R.; Palikonda, R.; Mordeen, M. L.; Minnis, P.

    2007-01-01

    This poster presentation reviews the process used to validate the GOES-10 satellite derived cloud and radiative properties. The ARM Mobile Facility (AMF) deployment at Pt Reyes, CA as part of the Marine Stratus Radiation Aerosol and Drizzle experiment (MASRAD), 14 March - 14 September 2005 provided an excellent chance to validate satellite cloud-property retrievals with the AMF's flexible suite of ground-based remote sensing instruments. For this comparison, NASA LaRC GOES10 satellite retrievals covering this region and period were re-processed using an updated version of the Visible Infrared Solar-Infrared Split-Window Technique (VISST), which uses data taken at 4 wavelengths (0.65, 3.9,11 and 12 m resolution), and computes broadband fluxes using improved CERES (Clouds and Earth's Radiant Energy System)-GOES-10 narrowband-to-broadband flux conversion coefficients. To validate MASRAD GOES-10 satellite-derived cloud property data, VISST-derived cloud amounts, heights, liquid water paths are compared with similar quantities derived from available ARM ground-based instrumentation and with CERES fluxes from Terra.

  13. MSG SEVIRI Applications for Weather and Climate: Cloud Properties and Calibrations

    NASA Technical Reports Server (NTRS)

    Minnis, Patrick; Nguyen, Louis; Smith, William L.; Palikonda, Rabindra; Doelling, David R.; Ayers, J. Kirk; Trepte, Qing Z.; Chang, Fu-Lung

    2006-01-01

    SEVIRI data are cross-calibrated against the corresponding Aqua and Terra MODIS channels. Compared to Terra MODIS, no significant trends are evident in the 0.65, 0.86, and 1.6 micron channel gains between May 2004 and May 2006, indicating excellent stability in the solar-channel sensors. On average, the corresponding Terra reflectances are 12, 14, and 1% greater than the their SEVIRI counterparts. The Terra 3.8- micron channel brightness temperatures T are 7 and 4 K greater than their SEVIRI counterparts during day and night, respectively. The average differences between T for MODIS and SEVIRI 8.6, 10.8, 12.0, and 13.3- micron channels are between 0.5 and 2 K. The cloud properties are being derived hourly over Europe and, in initial comparisons, agree well with surface observations. Errors caused by residual calibration uncertainties, terminator conditions, and inaccurate temperature and humidity profiles are still problematic. Future versions will address those errors and the effects of multilayered clouds.

  14. The Properties of Single Interstellar Clouds: Hopr Repeat Cycle 1, SIDE-2 Observations

    NASA Astrophysics Data System (ADS)

    Hobbs, Lewis

    1990-12-01

    WE PROPOSE TO USE THE ECHELLE GRATING OF THE HIGH RESOLUTION SPECTROGRAPH OVER A TWO-YEAR PERIOD TO OBSERVE THE PROFILES OF INTERSTELLAR ABSORPTION LINES. THE COLUMN DENSITES OF 18 NEUTRAL OR IONIZED FORMS OF THE ELEMENTS C,N,O,Mg,Si,P,S,Fe, AND Zn WILL BE MEASURED IN THE APPROXIMATELY 100 INDIVIDUAL INTERSTELLAR CLOUDS ALONG THE LIGHT PATHS TO 18 BRIGHT, BROAD-LINED STARS OF EARLY SPECTRAL TYPE WITHIN 1 KPC OF THE SUN. THE PRIMARY PURPOSE OF THE OBSERVATIONS IS TO DETERMINE MORE ACCURATELY THAN WAS HITHERTO POSSIBLE THE FUNDAMENTAL PHYSICAL PROPERTIES OF THE RESOLVED CLOUDS, INCLUDING LINEAR SIZE, TEMPERATURE, TOTAL DENSITY, FRACTIONAL IONIZATION AND THE RELATIVE ABUNDANCES OF THE 9 SELECTED ELEMENTS. THE REST OF THIS OBSERVING PROGRAM IS CONTAINED IN APPROVED PROPOSAL ID = 2251; THE PROGRAM EUNUMERATED HERE CONSISTS OF THAT PART OF OUR ORIGINAL PROGRAM WHICH CAN BE CARRIED OUT USING ONLY SIDE 2 OF THE GHRS. THIS PROGRAM THEREFORE CONSISTS OF ECH-B OBSERVATIONS OF EACH OF 4 STARS AT 7 WAVELENGTHS. PROGRAM 2251 SHOULD BE CONSULTED FOR ADDITIONAL DETAILS.

  15. The Properties of Single Interstellar Clouds: Cycle 1, SIDE-2 Observations

    NASA Astrophysics Data System (ADS)

    Hobbs, Lewis

    1990-12-01

    WE PROPOSE TO USE THE ECHELLE GRATING OF THE HIGH RESOLUTION SPECTROGRAPH OVER A TWO-YEAR PERIOD TO OBSERVE THE PROFILES OF INTERSTELLAR ABSORPTION LINES. THE COLUMN DENSITES OF 18 NEUTRAL OR IONIZED FORMS OF THE ELEMENTS C,N,O,Mg,Si,P,S,Fe, AND Zn WILL BE MEASURED IN THE APPROXIMATELY 100 INDIVIDUAL INTERSTELLAR CLOUDS ALONG THE LIGHT PATHS TO 18 BRIGHT, BROAD-LINED STARS OF EARLY SPECTRAL TYPE WITHIN 1 KPC OF THE SUN. THE PRIMARY PURPOSE OF THE OBSERVATIONS IS TO DETERMINE MORE ACCURATELY THAN WAS HITHERTO POSSIBLE THE FUNDAMENTAL PHYSICAL PROPERTIES OF THE RESOLVED CLOUDS, INCLUDING LINEAR SIZE, TEMPERATURE, TOTAL DENSITY, FRACTIONAL IONIZATION AND THE RELATIVE ABUNDANCES OF THE 9 SELECTED ELEMENTS. THE REST OF THIS OBSERVING PROGRAM IS CONTAINED IN APPROVED PROPOSAL ID = 2251; THE PROGRAM EUNUMERATED HERE CONSISTS OF THAT PART OF OUR ORIGINAL PROGRAM WHICH CAN BE CARRIED OUT USING ONLY SIDE 2 OF THE GHRS. THIS PROGRAM THEREFORE CONSISTS OF ECH-B OBSERVATIONS OF EACH OF 4 STARS AT 7 WAVELENGTHS. PROGRAM 2251 SHOULD BE CONSULTED FOR ADDITIONAL DETAILS.

  16. Characterizing the turbulent properties of the starless molecular cloud MBM 16

    SciTech Connect

    Pingel, N. M.; Stanimirović, Snezana; Lee, Min-Young; Lazarian, Alex; Burkhart, Blakesley; Lawrence, Allen; Murray, Claire; Peek, J. E. G.; Grcevich, Jana; Putman, Mary E.; Saul, Destry; Begum, Ayesha; Douglas, Kevin A.; Gibson, Steven J. E-mail: sstanimi@astro.wisc.edu

    2013-12-10

    We investigate turbulent properties of the non-star-forming, translucent molecular cloud MBM 16 by applying the statistical technique of a two-dimensional spatial power spectrum (SPS) on the neutral hydrogen (H I) observations obtained by the Galactic Arecibo L-Band Feed Array H I survey. The SPS, calculated over the range of spatial scales from 0.1 to 17 pc, is well represented with a single power-law function, with a slope ranging from –3.3 to –3.7 and being consistent over the velocity range of MBM 16 for a fixed velocity channel thickness. However, the slope varies significantly with the velocity slice thickness, suggesting that both velocity and density contribute to H I intensity fluctuations. By using this variation, we estimate the slope of three-dimensional density fluctuations in MBM 16 to be –3.7 ± 0.2. This is significantly steeper than what has been found for H I in the Milky Way plane, the Small Magellanic Cloud, or the Magellanic Bridge, suggesting that interstellar turbulence in MBM 16 is driven on scales >17 pc and that the lack of stellar feedback could be responsible for the steep power spectrum.

  17. Investigation of the effects of the macrophysical and microphysical properties of cirrus clouds on the retrieval of optical properties: Results for FIRE 2

    NASA Technical Reports Server (NTRS)

    Stackhouse, Paul W., Jr.; Stephens, Graeme L.

    1993-01-01

    Due to the prevalence and persistence of cirrus cloudiness across the globe, cirrus clouds are believed to have an important effect on the climate. Stephens et al., (1990) among others have shown that the important factor determining how cirrus clouds modulate the climate is the balance between the albedo and emittance effect of the cloud systems. This factor was shown to depend in part upon the effective sizes of the cirrus cloud particles. Since effective sizes of cirrus cloud microphysical distributions are used as a basis of parameterizations in climate models, it is crucial that the relationships between effective sizes and radiative properties be clearly established. In this preliminary study, the retrieval of cirrus cloud effective sizes are examined using a two dimensional radiative transfer model for a cirrus cloud case sampled during FIRE Cirrus 11. The purpose of this paper is to present preliminary results from the SHSG model demonstrating the sensitivity of the bispectral relationships of reflected radiances and thus the retrieval of effective sizes to phase function and dimensionality.

  18. How Various Sources of Uncertainty Affect Retrieval Uncertainty in the Optimal Estimation Framework Using a Non-precipitating Liquid Clouds Example

    NASA Astrophysics Data System (ADS)

    Xu, Z.; Mace, G. G.; Turner, D. D.; Posselt, D. J.

    2014-12-01

    Optimal estimation (OE) is a commonly used inverse method in the geosciences. In a Bayesian context, a set of measurements (y) is related to the state vector to be retrieved (x) by the forward model F(x). Assuming Gaussian statistics, OE returns an optimal solution and its associated uncertainty by minimizing the cost function that consists of the state vector-a priori state difference weighted by the a priori uncertainty and the measurement-forward model difference weighted by the uncertainties of observation and forward model. OE algorithms are easy to implement and are finding increasing use within communities attempting to derive, for instance, cloud and precipitation microphysical properties from remote sensing data. However, even though OE algorithms are simple to implement, obtaining rigorous uncertainty estimates from them is a significant challenge. Our objective with this work is to illustrate the growth of retrieval uncertainty within the OE framework due to various sources using simple real world examples of non-precipitating liquid clouds. Within the OE retrieval, several sources of uncertainties contribute to the overall retrieval uncertainty (Sx), including the measurement uncertainty (Sy), the uncertainties in a priori information (Sa) and uncertainties in the forward model due to imperfectly known parameters (Sb). In this study, two examples are given to demonstrate how uncertainties in Sy, Sa and Sb affect the ultimate retrieval uncertainty Sx. We apply OE technique to retrieve cloud liquid water content (LWC) and total number from measurements of radar reflectivity and extinction obtained in 2005 Marine Stratus/Stratocumulus Experiment (MASE). In the first example, the forward model is assumed perfect, which means all parameters are certain and Sb is zero. Then we perturb Sy and Sa separately and observe the response of Sx. We find the observation error Sy contributes significantly to the retrieval uncertainty under the assumption of "perfect

  19. Observation of the spectral-invariant properties of clouds in transition zones during MAGIC, A case study

    NASA Astrophysics Data System (ADS)

    Yang, W.; Marshak, A.; McBride, P. J.; Chiu, J. Y. C.; Knyazikhin, Y.; Schmidt, S.; Flynn, C. J.; Lewis, E. R.; Eloranta, E. W.

    2015-12-01

    The time-resolved hyper spectral measurements during MAGIC provide a unique opportunity to study both clouds and aerosols in transition zones between cloudy and clear skies. This presentation presents the spectral-invariant properties of cloud transition zones observed on two cases of July, 2013 using the measurements from the Shortwave Array Spectroradiometer-Zenith (SAS-Ze) and the Solar Spectral Flux Radiometer (SSFR). Though radiance measurements from the two instruments can be different possibly due to the calibration drifting, the spectral-invariant properties observed on the two instruments show some common features. These features indicate that the overall cloud effective particle size likely decreases during the transition from cloudy to clear skies in the two cases.

  20. Anomalous magnetosheath properties during Earth passage of an interplanetary magnetic cloud

    SciTech Connect

    Farrugia, C.J.; Erkaev, N.V.; Burlaga, L.F.

    1995-10-01

    In this work the authors present a model for the behavior of the magnetosheath during the passage of the earth thru an interplanetary magnetic cloud. They study the variation of plasma flow and field values as a result of this encounter. The unique feature of such encounters is that they present substantial changes in the solar wind conditions along the bow shock and magnetopause for periods of 1 to 2 days. The mach number upstream of the bow shock can be as low as 3, compared to normal value of 8 to 10. The mach number and magnetic shear across the magnetopause have a major impact on the magnetosheath properties. The authors use the encounter of January 14-15, 1988, as a basis for their model, and apply ideal MHD equations, by means of a boundary layer technique, to study changes in field and plasma flow patterns.

  1. Lidar Investigations of Aerosol, Cloud, and Boundary Layer Properties Over the ARM ACRF Sites

    SciTech Connect

    Turner, David D.; Ferrare, Richard

    2015-01-13

    The systematic and routine measurements of aerosol, water vapor, and clouds in the vertical column above the Atmospheric Radiation Measurement (ARM) sites from surface-based remote sensing systems provides a unique and comprehensive data source that can be used to characterize the boundary layer (i.e., the lowest 3 km of the atmosphere) and its evolution. New algorithms have been developed to provide critical datasets from ARM instruments, and these datasets have been used in long-term analyses to better understand the climatology of water vapor and aerosol over Darwin, the turbulent structure of the boundary layer and its statistical properties over Oklahoma, and to better determine the distribution of ice and aerosol particles over northern Alaska.

  2. Maternal nutrient restriction affects properties of skeletal muscle in offspring

    PubMed Central

    Zhu, Mei J; Ford, Stephen P; Means, Warrie J; Hess, Bret W; Nathanielsz, Peter W; Du, Min

    2006-01-01

    Maternal nutrient restriction (NR) affects fetal development with long-term consequences on postnatal health of offspring, including predisposition to obesity and diabetes. Most studies have been conducted in fetuses in late gestation, and little information is available on the persistent impact of NR from early to mid-gestation on properties of offspring skeletal muscle, which was the aim of this study. Pregnant ewes were subjected to 50% NR from day 28–78 of gestation and allowed to deliver. The longissimus dorsi muscle was sampled from 8-month-old offspring. Maternal NR during early to mid-gestation decreased the number of myofibres in the offspring and increased the ratio of myosin IIb to other isoforms by 17.6 ± 4.9% (P < 0.05) compared with offspring of ad libitum fed ewes. Activity of carnitine palmitoyltransferase-1, a key enzyme controlling fatty acid oxidation, was reduced by 24.7 ± 4.5% (P < 0.05) in skeletal muscle of offspring of NR ewes and would contribute to increased fat accumulation observed in offspring of NR ewes. Intramuscular triglyceride content (IMTG) was increased in skeletal muscle of NR lambs, a finding which may be linked to predisposition to diabetes in offspring of NR mothers, since enhanced IMTG predisposes to insulin resistance in skeletal muscle. Proteomic analysis by two-dimensional gel electrophoresis demonstrated downregulation of several catabolic enzymes in 8-month-old offspring of NR ewes. These data demonstrate that the early to mid-gestation period is important for skeletal muscle development. Impaired muscle development during this stage of gestation affects the number and composition of fibres in offspring which may lead to long-term physiological consequences, including predisposition to obesity and diabetes. PMID:16763001

  3. Force distribution affects vibrational properties in hard-sphere glasses.

    PubMed

    DeGiuli, Eric; Lerner, Edan; Brito, Carolina; Wyart, Matthieu

    2014-12-02

    We theoretically and numerically study the elastic properties of hard-sphere glasses and provide a real-space description of their mechanical stability. In contrast to repulsive particles at zero temperature, we argue that the presence of certain pairs of particles interacting with a small force f soften elastic properties. This softening affects the exponents characterizing elasticity at high pressure, leading to experimentally testable predictions. Denoting P(f) ~ f(θ(e)), the force distribution of such pairs and ϕ(c) the packing fraction at which pressure diverges, we predict that (i) the density of states has a low-frequency peak at a scale ω*, rising up to it as D(ω) ~ ω(2+a), and decaying above ω* as D(ω) ~ ω(-a) where a = (1 - θ(e))/(3 + θ(e)) and ω is the frequency, (ii) shear modulus and mean-squared displacement are inversely proportional with ⟨δR²⟩ ~ 1/μ ~ (ϕ(c) - ϕ)(κ), where κ = 2 - 2/(3 + θ(e)), and (iii) continuum elasticity breaks down on a scale ℓ(c) ~ 1/√(δz) ~ (ϕ(c) - ϕ)(-b), where b = (1 + θ(e))/(6 + 2θ(e)) and δz = z - 2d, where z is the coordination and d the spatial dimension. We numerically test (i) and provide data supporting that θ(e) ≈ 0.41 in our bidisperse system, independently of system preparation in two and three dimensions, leading to κ ≈ 1.41, a ≈ 0.17, and b ≈ 0.21. Our results for the mean-square displacement are consistent with a recent exact replica computation for d = ∞, whereas some observations differ, as rationalized by the present approach.

  4. Retrieval of Polar Stratospheric Cloud Microphysical Properties From Lidar Measurements: Dependence on Particle Shape Assumptions

    NASA Technical Reports Server (NTRS)

    Reichardt, Susanne; Reichardt, Jens; Yang, Ping; McGee, Thomas J.; Einaudi, Franco (Technical Monitor)

    2001-01-01

    Knowledge of particle sizes and number densities of polar stratospheric clouds (PSCs) is highly important, because they are critical parameters for the modeling of the ozone chemistry of the stratosphere. In situ measurements of PSC particles are rare. the main instrument for the accumulation of PSC data are lidar systems. Therefore the derivation of some microphysical properties of PSCS from the optical parameters measured by lidars would be highly beneficial for ozone research. Inversion of lidar data obtained in the presence of PSCs formed from crystalline particles type 11 and the various nitric acid tri Ydrrate (NAT) types cannot be easily accomplished, because a suitable scattering theory for small faceted crystals has not been readily available tip to now. As a consequence, the T-matrix method is commonly used for the interpretation of these PSC lidar data. Here the assumption is made that the optical properties of an ensemble of spheroids resemble those of crystalline PSCs, and microphysical properties of the PSC are inferred from the optical signatures of the PSC at two or more wavelengths. The problem with the T-matrix approach is that the assumption of spheroidal instead of faceted particles can lead to dramatically wrong results: Usually cloud particle properties are deduced from analysis of lidar profiles of backscatter ratio and depolarization ratio. The particle contribution to the backscatter ratio is given by the product of the particle number density and the backscattering cross section. The latter is proportional to the value of the particle's scattering phase function at 180 degrees scattering angle. At 180 degrees however, the phase functions of rough, faceted crystals and of spheroids with same maximum dimension differ by a factor of 6. From this it follows that for a PSC consisting of faceted crystals, the particle number density is underestimated by roughly the same factor if spheroidal particles are unrealistically assumed. We are currently

  5. Mixed-phase cloud radiative properties over Ross Island, Antarctica: The influence of various synoptic-scale atmospheric circulation regimes

    NASA Astrophysics Data System (ADS)

    Scott, Ryan C.; Lubin, Dan

    2014-06-01

    Spectral downwelling shortwave irradiance measurements made beneath overcast stratiform cloud decks at Ross Island, Antarctica (77.5°S, 167°E), are used in conjunction with discrete ordinates-based radiative transfer simulations to examine how mixed-phase clouds influence shortwave irradiance at the surface during austral spring-summer. From 10 October 2012 until 4 February 2013, an Analytical Spectral Devices (ASD, Inc.) spectroradiometer deployed at the Arrival Heights (77.82°S, 166.65°E) laboratory of McMurdo Station measured in 1 min averages the downwelling spectral hemispheric (direct plus diffuse) irradiance spanning visible (VIS) and near-infrared regions of the solar spectrum, from 350 to 2200 nm. Conservative-scattering cloud optical depth τc is retrieved in the interval 1022-1033 nm, where the albedo of the snow-covered surface is lower than at VIS wavelengths. The impact of liquid versus mixed-phase cloud properties on the surface shortwave energy budget is discerned using irradiances in the 1.6 μm window. Five case studies employ NASA A-Train satellite and ancillary meteorological data sets to investigate the macrophysical, microphysical, and shortwave radiative characteristics of clouds possessing distinct meteorological histories. Cloud systems within marine air masses arriving at Ross Island after transiting the West Antarctic ice sheet (WAIS) and the Ross Ice Shelf are radiatively dominated by the ice phase. In contrast, moist marine air moving directly onshore from the Ross Sea brings low clouds with a stronger influence of liquid water. Deep cyclonic disturbances over the Ross Sea are seen to be limited in their ability to deliver significant moisture as far south as Ross Island, where clouds are mainly optically thin.

  6. Microphysics of Pyrocumulonimbus Clouds

    NASA Technical Reports Server (NTRS)

    Jensen, Eric; Ackerman, Andrew S.; Fridlind, Ann

    2004-01-01

    The intense heat from forest fires can generate explosive deep convective cloud systems that inject pollutants to high altitudes. Both satellite and high-altitude aircraft measurements have documented cases in which these pyrocumulonimbus clouds inject large amounts of smoke well into the stratosphere (Fromm and Servranckx 2003; Jost et al. 2004). This smoke can remain in the stratosphere, be transported large distances, and affect lower stratospheric chemistry. In addition recent in situ measurements in pyrocumulus updrafts have shown that the high concentrations of smoke particles have significant impacts on cloud microphysical properties. Very high droplet number densities result in delayed precipitation and may enhance lightning (Andrew et al. 2004). Presumably, the smoke particles will also lead to changes in the properties of anvil cirrus produces by the deep convection, with resulting influences on cloud radiative forcing. In situ sampling near the tops of mature pyrocumulonimbus is difficult due to the high altitude and violence of the storms. In this study, we use large eddy simulations (LES) with size-resolved microphysics to elucidate physical processes in pyrocumulonimbus clouds.

  7. Exploring the Effects of Cloud Vertical Structure on Cloud Microphysical Retrievals based on Polarized Reflectances

    NASA Astrophysics Data System (ADS)

    Miller, D. J.; Zhang, Z.; Platnick, S. E.; Ackerman, A. S.; Cornet, C.; Baum, B. A.

    2013-12-01

    A polarized cloud reflectance simulator was developed by coupling an LES cloud model with a polarized radiative transfer model to assess the capabilities of polarimetric cloud retrievals. With future remote sensing campaigns like NASA's Aerosols/Clouds/Ecosystems (ACE) planning to feature advanced polarimetric instruments it is important for the cloud remote sensing community to understand the retrievable information available and the related systematic/methodical limitations. The cloud retrieval simulator we have developed allows us to probe these important questions in a realistically relevant test bed. Our simulator utilizes a polarized adding-doubling radiative transfer model and an LES cloud field from a DHARMA simulation (Ackerman et al. 2004) with cloud properties based on the stratocumulus clouds observed during the DYCOMS-II field campaign. In this study we will focus on how the vertical structure of cloud microphysics can influence polarized cloud effective radius retrievals. Numerous previous studies have explored how retrievals based on total reflectance are affected by cloud vertical structure (Platnick 2000, Chang and Li 2002) but no such studies about the effects of vertical structure on polarized retrievals exist. Unlike the total cloud reflectance, which is predominantly multiply scattered light, the polarized reflectance is primarily the result of singly scattered photons. Thus the polarized reflectance is sensitive to only the uppermost region of the cloud (tau~<1) where photons can scatter once and still escape before being scattered again. This means that retrievals based on polarized reflectance have the potential to reveal behaviors specific to the cloud top. For example cloud top entrainment of dry air, a major influencer on the microphysical development of cloud droplets, can be potentially studied with polarimetric retrievals.

  8. CalNex cloud properties retrieved from a ship-based spectrometer and comparisons with satellite and aircraft retrieved cloud properties

    NASA Astrophysics Data System (ADS)

    McBride, P. J.; Schmidt, K. S.; Pilewskie, P.; Walther, A.; Heidinger, A. K.; Wolfe, D. E.; Fairall, C. W.; Lance, S.

    2012-10-01

    An algorithm to retrieve cloud optical thickness and effective radius (reff) from spectral transmittance was applied to radiance and irradiance observations of the Solar Spectral Flux Radiometer (SSFR) during the Research at the Nexus of Air Quality and Climate Change Campaign (CalNex). Data from an overcast day, 16 May 2010, was used to validate the algorithm. Retrievals from the SSFR, deployed on the Woods Hole Oceanic Institute R/V Atlantis, were compared to retrievals made from an airborne SSFR, the Geostationary Operations Environmental Satellite (GOES), an Atlantis-based microwave radiometer, and the Moderate Resolution Imaging Spectroradiometer. In situ observations of reff during a flight over the Atlantis were compared to the Atlantis SSFR and GOES retrievals. The cloud statistics for the CalNex campaign were compared to previous studies. The agreement between the different retrievals, quantified by determining the number of coincident observations when retrieval uncertainty overlapped, improved as the difference