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Sample records for middle cloud layer

  1. Thermal structure of the Venus atmosphere in the middle cloud layer

    NASA Technical Reports Server (NTRS)

    Linkin, V. M.; Seiff, A.; Ragent, B.; Young, R. E.; Elson, L. S.; Preston, A.

    1986-01-01

    Thermal structure measurements obtained by the two VEGA balloons show the Venus middle cloud layer to be generally adiabatic. Temperatures measured by the two balloons at locations roughly symmetric about the equator differed by about 6.5 kelvins at a given pressure. The VEGA-2 temperatures were about 2.5 kelvins cooler and those of VEGA-1 about 4 kelvins warmer than temperatures measured by the Pioneer Venus Large Probe at these levels. Data taken by the VEGA-2 lander as it passed through the middle cloud agreed with those of the VEGA-2 balloon. Study of individual frames of the balloon data suggests the presence of multiple discrete air masses that are internally adiabatic but lie on slightly different adiabats. These adiabats, for a given balloon, can differ in temperature by as much as 1 kelvin at a given pressure.

  2. 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.

  3. Cloud layer thicknesses from a combination of surface and upper-air observations

    NASA Technical Reports Server (NTRS)

    Poore, Kirk D.; Wang, Junhong; Rossow, William B.

    1995-01-01

    Cloud layer thicknesses are derived from base and top altitudes by combining 14 years (1975-1988) of surface and upper-air observations at 63 sites in the Northern Hemisphere. Rawinsonde observations are employed to determine the locations of cloud-layer top and base by testing for dewpoint temperature depressions below some threshold value. Surface observations serve as quality checks on the rawinsonde-determined cloud properties and provide cloud amount and cloud-type information. The dataset provides layer-cloud amount, cloud type, high, middle, or low height classes, cloud-top heights, base heights and layer thicknesses, covering a range of latitudes from 0 deg to 80 deg N. All data comes from land sites: 34 are located in continental interiors, 14 are near coasts, and 15 are on islands. The uncertainties in the derived cloud properties are discussed. For clouds classified by low-, mid-, and high-top altitudes, there are strong latitudinal and seasonal variations in the layer thickness only for high clouds. High-cloud layer thickness increases with latitude and exhibits different seasonal variations in different latitude zones: in summer, high-cloud layer thickness is a maximum in the Tropics but a minimum at high latitudes. For clouds classified into three types by base altitude or into six standard morphological types, latitudinal and seasonal variations in layer thickness are very small. The thickness of the clear surface layer decreases with latitude and reaches a summer minimum in the Tropics and summer maximum at higher latitudes over land, but does not vary much over the ocean. Tropical clouds occur in three base-altitude groups and the layer thickness of each group increases linearly with top altitude. Extratropical clouds exhibit two groups, one with layer thickness proportional to their cloud-top altitude and one with small (less than or equal to 1000 m) layer thickness independent of cloud-top altitude.

  4. "Analysis of the multi-layered cloud radiative effects at the surface using A-train data"

    NASA Astrophysics Data System (ADS)

    Viudez-Mora, A.; Smith, W. L., Jr.; Kato, S.

    2017-12-01

    Clouds cover about 74% of the planet and they are an important part of the climate system and strongly influence the surface energy budget. The cloud vertical distribution has important implications in the atmospheric heating and cooling rates. Based on observations by active sensors in the A-train satellite constellation, CALIPSO [Winker et. al, 2010] and CloudSat [Stephens et. al, 2002], more than 1/3 of all clouds are multi-layered. Detection and retrieval of multi-layer cloud physical properties are needed in understanding their effects on the surface radiation budget. This study examines the sensitivity of surface irradiances to cloud properties derived from satellite sensors. Surface irradiances were computed in two different ways, one using cloud properties solely from MODerate resolution Imaging Spectroradiometer (MODIS), and the other using MODIS data supplemented with CALIPSO and CloudSat (hereafter CLCS) cloud vertical structure information [Kato et. al, 2010]. Results reveal that incorporating more precise and realistic cloud properties from CLCS into radiative transfer calculations yields improved estimates of cloud radiative effects (CRE) at the surface (CREsfc). The calculations using only MODIS cloud properties, comparisons of the computed CREsfc for 2-layer (2L) overcast CERES footprints, CLCS reduces the SW CRE by 1.5±26.7 Wm-2, increases the LW CRE by 4.1±12.7 Wm-2, and increases the net CREsfc by 0.9±46.7 Wm-2. In a subsequent analysis, we classified up to 6 different combinations of multi-layered clouds depending on the cloud top height as: High-high (HH), high-middle (HM), high-low (HL), middle-middle (MM), middle-low (ML) and low-low (LL). The 3 most frequent 2L cloud systems were: HL (56.1%), HM (22.3%) and HH (12.1%). For these cases, the computed CREsfc estimated using CLCS data presented the most significant differences when compared using only MODIS data. For example, the differences for the SW and Net CRE in the case HH was 12.3±47

  5. Equatorial jet in the lower to middle cloud layer of Venus revealed by Akatsuki

    NASA Astrophysics Data System (ADS)

    Horinouchi, Takeshi; Murakami, Shin-Ya; Satoh, Takehiko; Peralta, Javier; Ogohara, Kazunori; Kouyama, Toru; Imamura, Takeshi; Kashimura, Hiroki; Limaye, Sanjay S.; McGouldrick, Kevin; Nakamura, Masato; Sato, Takao M.; Sugiyama, Ko-Ichiro; Takagi, Masahiro; Watanabe, Shigeto; Yamada, Manabu; Yamazaki, Atsushi; Young, Eliot F.

    2017-09-01

    The Venusian atmosphere is in a state of superrotation where prevailing westward winds move much faster than the planet's rotation. Venus is covered with thick clouds that extend from about 45 to 70 km altitude, but thermal radiation emitted from the lower atmosphere and the surface on the planet's nightside escapes to space at narrow spectral windows of the near-infrared. The radiation can be used to estimate winds by tracking the silhouettes of clouds in the lower and middle cloud regions below about 57 km in altitude. Estimates of wind speeds have ranged from 50 to 70 m s-1 at low to mid-latitudes, either nearly constant across latitudes or with winds peaking at mid-latitudes. Here we report the detection of winds at low latitude exceeding 80 m s-1 using IR2 camera images from the Akatsuki orbiter taken during July and August 2016. The angular speed around the planetary rotation axis peaks near the equator, which we suggest is consistent with an equatorial jet, a feature that has not been observed previously in the Venusian atmosphere. The mechanism producing the jet remains unclear. Our observations reveal variability in the zonal flow in the lower and middle cloud region that may provide clues to the dynamics of Venus's atmospheric superrotation.

  6. Equatorial jet in the lower to middle cloud layer of Venus revealed by Akatsuki.

    PubMed

    Horinouchi, Takeshi; Murakami, Shin-Ya; Satoh, Takehiko; Peralta, Javier; Ogohara, Kazunori; Kouyama, Toru; Imamura, Takeshi; Kashimura, Hiroki; Limaye, Sanjay S; McGouldrick, Kevin; Nakamura, Masato; Sato, Takao M; Sugiyama, Ko-Ichiro; Takagi, Masahiro; Watanabe, Shigeto; Yamada, Manabu; Yamazaki, Atsushi; Young, Eliot F

    2017-01-01

    The Venusian atmosphere is in a state of superrotation where prevailing westward winds move much faster than the planet's rotation. Venus is covered with thick clouds that extend from about 45 to 70 km altitude, but thermal radiation emitted from the lower atmosphere and the surface on the planet's night-side escapes to space at narrow spectral windows of near-infrared. The radiation can be used to estimate winds by tracking the silhouettes of clouds in the lower and middle cloud regions below about 57 km in altitude. Estimates of wind speeds have ranged from 50 to 70 m/s at low- to mid-latitudes, either nearly constant across latitudes or with winds peaking at mid-latitudes. Here we report the detection of winds at low latitude exceeding 80 m/s using IR2 camera images from the Akatsuki orbiter taken during July and August 2016. The angular speed around the planetary rotation axis peaks near the equator, which we suggest is consistent with an equatorial jet, a feature that has not been observed previously in the Venusian atmosphere. The mechanism producing the jet remains unclear. Our observations reveal variability in the zonal flow in the lower and middle cloud region that may provide new challenges and clues to the dynamics of Venus's atmospheric superrotation.

  7. Characteristics of middle and upper tropospheric clouds as deduced from rawinsonde data

    NASA Technical Reports Server (NTRS)

    Starr, D. D. O.; Cox, S. K.

    1982-01-01

    The static environment of middle and upper tropospheric clouds is characterized. Computed relative humidity with respect to ice is used to diagnose the presence of cloud layer. The deduced seasonal mean cloud cover estimates based on this technique are shown to be reasonable. The cases are stratified by season and pressure thickness, and the dry static stability, vertical wind speed shear, and Richardson number are computed for three layers for each case. Mean values for each parameter are presented for each stratification and layer. The relative frequency of occurrence of various structures is presented for each stratification. The observed values of each parameter and the observed structure of each parameter are quite variable. Structures corresponding to any of a number of different conceptual models may be found. Moist adiabatic conditions are not commonly observed and the stratification based on thickness yields substantially different results for each group.

  8. Equatorial jet in the lower to middle cloud layer of Venus revealed by Akatsuki

    PubMed Central

    Horinouchi, Takeshi; Murakami, Shin-ya; Satoh, Takehiko; Peralta, Javier; Ogohara, Kazunori; Kouyama, Toru; Imamura, Takeshi; Kashimura, Hiroki; Limaye, Sanjay S.; McGouldrick, Kevin; Nakamura, Masato; Sato, Takao M.; Sugiyama, Ko-ichiro; Takagi, Masahiro; Watanabe, Shigeto; Yamada, Manabu; Yamazaki, Atsushi; Young, Eliot F.

    2018-01-01

    The Venusian atmosphere is in a state of superrotation where prevailing westward winds move much faster than the planet’s rotation. Venus is covered with thick clouds that extend from about 45 to 70 km altitude, but thermal radiation emitted from the lower atmosphere and the surface on the planet’s night-side escapes to space at narrow spectral windows of near-infrared. The radiation can be used to estimate winds by tracking the silhouettes of clouds in the lower and middle cloud regions below about 57 km in altitude. Estimates of wind speeds have ranged from 50 to 70 m/s at low- to mid-latitudes, either nearly constant across latitudes or with winds peaking at mid-latitudes. Here we report the detection of winds at low latitude exceeding 80 m/s using IR2 camera images from the Akatsuki orbiter taken during July and August 2016. The angular speed around the planetary rotation axis peaks near the equator, which we suggest is consistent with an equatorial jet, a feature that has not been observed previously in the Venusian atmosphere. The mechanism producing the jet remains unclear. Our observations reveal variability in the zonal flow in the lower and middle cloud region that may provide new challenges and clues to the dynamics of Venus’s atmospheric superrotation. PMID:29887914

  9. Modeling marine boundary-layer clouds with a two-layer model: A one-dimensional simulation

    NASA Technical Reports Server (NTRS)

    Wang, Shouping

    1993-01-01

    A two-layer model of the marine boundary layer is described. The model is used to simulate both stratocumulus and shallow cumulus clouds in downstream simulations. Over cold sea surfaces, the model predicts a relatively uniform structure in the boundary layer with 90%-100% cloud fraction. Over warm sea surfaces, the model predicts a relatively strong decoupled and conditionally unstable structure with a cloud fraction between 30% and 60%. A strong large-scale divergence considerably limits the height of the boundary layer and decreases relative humidity in the upper part of the cloud layer; thus, a low cloud fraction results. The efffects of drizzle on the boundary-layer structure and cloud fraction are also studied with downstream simulations. It is found that drizzle dries and stabilizes the cloud layer and tends to decouple the cloud from the subcloud layer. Consequently, solid stratocumulus clouds may break up and the cloud fraction may decrease because of drizzle.

  10. Cloud effects on middle ultraviolet global radiation

    NASA Technical Reports Server (NTRS)

    Borkowski, J.; Chai, A.-T.; Mo, T.; Green, A. E. O.

    1977-01-01

    An Eppley radiometer and a Robertson-Berger sunburn meter are employed along with an all-sky camera setup to study cloud effects on middle ultraviolet global radiation at the ground level. Semiempirical equations to allow for cloud effects presented in previous work are compared with the experimental data. The study suggests a means of defining eigenvectors of cloud patterns and correlating them with the radiation at the ground level.

  11. RACORO Extended-Term Aircraft Observations of Boundary-Layer Clouds

    NASA Technical Reports Server (NTRS)

    Vogelmann, Andrew M.; McFarquhar, Greg M.; Ogren, John A.; Turner, David D.; Comstock, Jennifer M.; Feingold, Graham; Long, Charles N.; Jonsson, Haflidi H.; Bucholtz, Anthony; Collins, Don R.; hide

    2012-01-01

    Small boundary-layer clouds are ubiquitous over many parts of the globe and strongly influence the Earths radiative energy balance. However, our understanding of these clouds is insufficient to solve pressing scientific problems. For example, cloud feedback represents the largest uncertainty amongst all climate feedbacks in general circulation models (GCM). Several issues complicate understanding boundary-layer clouds and simulating them in GCMs. The high spatial variability of boundary-layer clouds poses an enormous computational challenge, since their horizontal dimensions and internal variability occur at spatial scales much finer than the computational grids used in GCMs. Aerosol-cloud interactions further complicate boundary-layer cloud measurement and simulation. Additionally, aerosols influence processes such as precipitation and cloud lifetime. An added complication is that at small scales (order meters to 10s of meters) distinguishing cloud from aerosol is increasingly difficult, due to the effects of aerosol humidification, cloud fragments and photon scattering between clouds.

  12. Contrasting Cloud Composition Between Coupled and Decoupled Marine Boundary Layer Clouds

    NASA Astrophysics Data System (ADS)

    WANG, Z.; Mora, M.; Dadashazar, H.; MacDonald, A.; Crosbie, E.; Bates, K. H.; Coggon, M. M.; Craven, J. S.; Xian, P.; Campbell, J. R.; AzadiAghdam, M.; Woods, R. K.; Jonsson, H.; Flagan, R. C.; Seinfeld, J.; Sorooshian, A.

    2016-12-01

    Marine stratocumulus clouds often become decoupled from the vertical layer immediately above the ocean surface. This study contrasts cloud chemical composition between coupled and decoupled marine stratocumulus clouds. Cloud water and droplet residual particle composition were measured in clouds off the California coast during three airborne experiments in July-August of separate years (E-PEACE 2011, NiCE 2013, BOAS 2015). Decoupled clouds exhibited significantly lower overall mass concentrations in both cloud water and droplet residual particles, consistent with reduced cloud droplet number concentration and sub-cloud aerosol (Dp > 100 nm) number concentration, owing to detachment from surface sources. Non-refractory sub-micrometer aerosol measurements show that coupled clouds exhibit higher sulfate mass fractions in droplet residual particles, owing to more abundant precursor emissions from the ocean and ships. Consequently, decoupled clouds exhibited higher mass fractions of organics, nitrate, and ammonium in droplet residual particles, owing to effects of long-range transport from more distant sources. Total cloud water mass concentration in coupled clouds was dominated by sodium and chloride, and their mass fractions and concentrations exceeded those in decoupled clouds. Conversely, with the exception of sea salt constituents (e.g., Cl, Na, Mg, K), cloud water mass fractions of all species examined were higher in decoupled clouds relative to coupled clouds. These results suggest that an important variable is the extent to which clouds are coupled to the surface layer when interpreting microphysical data relevant to clouds and aerosol particles.

  13. Initial studies of middle and upper tropospheric stratiform clouds

    NASA Technical Reports Server (NTRS)

    Cox, S. K.

    1982-01-01

    The spatial and temporal occurrence of cloud layers, the development of a physical-numerical model to simulate the life cycles of tropospheric cloud layers, and the design of an observational program to study the properties of these layers are described.

  14. A modeling study of marine boundary layer clouds

    NASA Technical Reports Server (NTRS)

    Wang, Shouping; Fitzjarrald, Daniel E.

    1993-01-01

    Marine boundary layer (MBL) clouds are important components of the earth's climate system. These clouds drastically reduce the amount of solar radiation absorbed by the earth, but have little effect on the emitted infrared radiation on top of the atmosphere. In addition, these clouds are intimately involved in regulating boundary layer turbulent fluxes. For these reasons, it is important that general circulation models used for climate studies must realistically simulate the global distribution of the MBL. While the importance of these cloud systems is well recognized, many physical processes involved in these clouds are poorly understood and their representation in large-scale models remains an unresolved problem. The present research aims at the development and improvement of the parameterization of these cloud systems and an understanding of physical processes involved. This goal is addressed in two ways. One is to use regional modeling approach to validate and evaluate two-layer marine boundary layer models using satellite and ground-truth observations; the other is to combine this simple model with a high-order turbulence closure model to study the transition processes from stratocumulus to shallow cumulus clouds. Progress made in this effort is presented.

  15. Contrasting cloud composition between coupled and decoupled marine boundary layer clouds

    NASA Astrophysics Data System (ADS)

    Wang, Zhen; Mora Ramirez, Marco; Dadashazar, Hossein; MacDonald, Alex B.; Crosbie, Ewan; Bates, Kelvin H.; Coggon, Matthew M.; Craven, Jill S.; Lynch, Peng; Campbell, James R.; Azadi Aghdam, Mojtaba; Woods, Roy K.; Jonsson, Haflidi; Flagan, Richard C.; Seinfeld, John H.; Sorooshian, Armin

    2016-10-01

    Marine stratocumulus clouds often become decoupled from the vertical layer immediately above the ocean surface. This study contrasts cloud chemical composition between coupled and decoupled marine stratocumulus clouds for dissolved nonwater substances. Cloud water and droplet residual particle composition were measured in clouds off the California coast during three airborne experiments in July-August of separate years (Eastern Pacific Emitted Aerosol Cloud Experiment 2011, Nucleation in California Experiment 2013, and Biological and Oceanic Atmospheric Study 2015). Decoupled clouds exhibited significantly lower air-equivalent mass concentrations in both cloud water and droplet residual particles, consistent with reduced cloud droplet number concentration and subcloud aerosol (Dp > 100 nm) number concentration, owing to detachment from surface sources. Nonrefractory submicrometer aerosol measurements show that coupled clouds exhibit higher sulfate mass fractions in droplet residual particles, owing to more abundant precursor emissions from the ocean and ships. Consequently, decoupled clouds exhibited higher mass fractions of organics, nitrate, and ammonium in droplet residual particles, owing to effects of long-range transport from more distant sources. Sodium and chloride dominated in terms of air-equivalent concentration in cloud water for coupled clouds, and their mass fractions and concentrations exceeded those in decoupled clouds. Conversely, with the exception of sea-salt constituents (e.g., Cl, Na, Mg, and K), cloud water mass fractions of all species examined were higher in decoupled clouds relative to coupled clouds. Satellite and Navy Aerosol Analysis and Prediction System-based reanalysis data are compared with each other, and the airborne data to conclude that limitations in resolving boundary layer processes in a global model prevent it from accurately quantifying observed differences between coupled and decoupled cloud composition.

  16. The evaporatively driven cloud-top mixing layer

    NASA Astrophysics Data System (ADS)

    Mellado, Juan Pedro

    2010-11-01

    Turbulent mixing caused by the local evaporative cooling at the top cloud-boundary of stratocumuli will be discussed. This research is motivated by the lack of a complete understanding of several phenomena in that important region, which translates into an unacceptable variability of order one in current models, including those employed in climate research. The cloud-top mixing layer is a simplified surrogate to investigate, locally, particular aspects of the fluid dynamics at the boundary between the stratocumulus clouds and the upper cloud-free air. In this work, direct numerical simulations have been used to study latent heat effects. The problem is the following: When the cloud mixes with the upper cloud-free layer, relatively warm and dry, evaporation tends to cool the mixture and, if strong enough, the buoyancy reversal instability develops. This instability leads to a turbulent convection layer growing next to the upper boundary of the cloud, which is, in several aspects, similar to free convection below a cold horizontal surface. In particular, results show an approximately self-preserving behavior that is characterized by the molecular buoyancy flux at the inversion base, fact that helps to explain the difficulties found when doing large-eddy simulations of this problem using classical subgrid closures.

  17. Evaluation of multi-layer cloud detection based on MODIS CO2-slicing algorithm with CALIPSO-CloudSat measurements.

    NASA Astrophysics Data System (ADS)

    Viudez-Mora, A.; Kato, S.; Smith, W. L., Jr.; Chang, F. L.

    2016-12-01

    Knowledge of the vertical cloud distribution is important for a variety of climate and weather applications. The cloud overlapping variations greatly influence the atmospheric heating/cooling rates, with implications for the surface-troposphere radiative balance, global circulation and precipitation. Additionally, an accurate knowledge of the multi-layer cloud distribution in real-time can be used in applications such safety condition for aviation through storms and adverse weather conditions. In this study, we evaluate a multi-layered cloud algorithm (Chang et al. 2005) based on MODIS measurements aboard Aqua satellite (MCF). This algorithm uses the CO2-slicing technique combined with cloud properties determined from VIS, IR and NIR channels to locate high thin clouds over low-level clouds, and retrieve the τ of each layer. We use CALIPSO (Winker et. al, 2010) and CloudSat (Stephens et. al, 2002) (CLCS) derived cloud vertical profiles included in the C3M data product (Kato et al. 2010) to evaluate MCF derived multi-layer cloud properties. We focus on 2 layer overlapping and 1-layer clouds identified by the active sensors and investigate how well these systems are identified by the MODIS multi-layer technique. The results show that for these multi-layered clouds identified by CLCS, the MCF correctly identifies about 83% of the cases as multi-layer. However, it is found that the upper CTH is underestimated by about 2.6±0.4 km, because the CO2-slicing technique is not as sensitive to the cloud physical top as the CLCS. The lower CTH agree better with differences found to be about 1.2±0.5 km. Another outstanding issue for the MCF approach is the large number of multi-layer false alarms that occur in single-layer conditions. References: Chang, F.-L., and Z. Li, 2005: A new method for detection of cirrus overlapping water clouds and determination of their optical properties. J. Atmos. Sci., 62. Kato, S., et al. (2010), Relationships among cloud occurrence frequency

  18. Temperature and ice layer trends in the summer middle atmosphere

    NASA Astrophysics Data System (ADS)

    Lübken, F.-J.; Berger, U.

    2012-04-01

    We present results from our LIMA model (Leibniz Institute Middle Atmosphere Model) which nicely reproduces mean conditions of the summer mesopause region and also mean characteristics of ice layers known as noctilucent clouds. LIMA nudges to ECMWF data in the troposphere and lower stratosphere which influences the background conditions in the mesosphere. We study temperature trends in the mesosphere at middle and polar latitudes and compared with temperature trends from satellites, lidar, and phase height observations. For the first time large observed temperature trends in the summer mesosphere can be reproduced and explained by a model. As will be shown, stratospheric ozone has a major impact on temperature trends in the summer mesosphere. The temperature trend is not uniform in time: it is moderate from 1961 (the beginning of our record) until the beginning of the 1980s. Thereafter, temperatures decrease much stronger until the mid 1990s. Thereafter, temperatures are nearly constant or even increase with time. As will be shown, trends in ozone and carbon dioxide explain most of this behavior. Ice layers in the summer mesosphere are very sensitive to background conditions and are therefore considered to be appropriate tracers for long term variations in the middle atmosphere. We use LIMA background conditions to determine ice layer characteristics in the mesopause region. We compare our results with measurements, for example with albedos from the SBUV satellites, and show that we can nicely reproduce observed trends. It turns out that temperature trends are positive (negative) in the upper (lower) part of the ice layer regime. This complicates an interpretation of NLC long term variations in terms of temperature trends.

  19. 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 processesmore » 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

  20. [CII] observations of H2 molecular layers in transition clouds

    NASA Astrophysics Data System (ADS)

    Velusamy, T.; Langer, W. D.; Pineda, J. L.; Goldsmith, P. F.; Li, D.; Yorke, H. W.

    2010-10-01

    We present the first results on the diffuse transition clouds observed in [CII] line emission at 158 μm (1.9 THz) towards Galactic longitudes near 340° (5 LOSs) & 20° (11 LOSs) as part of the HIFI tests and GOT C+ survey. Out of the total 146 [CII] velocity components detected by profile fitting we identify 53 as diffuse molecular clouds with associated 12CO emission but without 13CO emission and characterized by AV < 5 mag. We estimate the fraction of the [CII] emission in the diffuse HI layer in each cloud and then determine the [CII] emitted from the molecular layers in the cloud. We show that the excess [CII] intensities detected in a few clouds is indicative of a thick H2 layer around the CO core. The wide range of clouds in our sample with thin to thick H2 layers suggests that these are at various evolutionary states characterized by the formation of H2 and CO layers from HI and C+, respectively. In about 30% of the clouds the H2 column densities (“dark gas”) traced by the [CII] is 50% or more than that traced by 12CO emission. On the average ~25% of the total H2 in these clouds is in an H2 layer which is not traced by CO. We use the HI, [CII], and 12CO intensities in each cloud along with simple chemical models to obtain constraints on the FUV fields and cosmic ray ionization rates. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

  1. A Climatology of Midlatitude Continental Clouds from the ARM SGP Central Facility. Part II; Cloud Fraction and Radiative Forcing

    NASA Technical Reports Server (NTRS)

    Dong, Xiquan; Xi, Baike; Minnis, Patrick

    2006-01-01

    Data collected at the Department of Energy Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) central facility are analyzed for determining the variability of cloud fraction and radiative forcing at several temporal scales between January 1997 and December 2002. Cloud fractions are estimated for total cloud cover and for single-layer low (0-3 km), middle (3-6 km), and high clouds (greater than 6 km) using ARM SGP ground-based paired lidar-radar measurements. Shortwave (SW), longwave (LW), and net cloud radiative forcings (CRF) are derived from up- and down-looking standard precision spectral pyranometers and precision infrared radiometer measurements. The annual averages of total, and single-layer, nonoverlapped low, middle and high cloud fractions are 0.49, 0.11, 0.03, and 0.17, respectively. Total and low cloud amounts were greatest from December through March and least during July and August. The monthly variation of high cloud amount is relatively small with a broad maximum from May to August. During winter, total cloud cover varies diurnally with a small amplitude, mid-morning maximum and early evening minimum, and during summer it changes by more than 0.14 over the daily cycle with a pronounced early evening minimum. The diurnal variations of mean single-layer cloud cover change with season and cloud height. Annual averages of all-sky, total, and single-layer high, middle, and low LW CRFs are 21.4, 40.2, 16.7, 27.2, and 55.0 Wm(sup -2), respectively; and their SW CRFs are -41.5, -77.2, -37.0, -47.0, and -90.5 Wm(sup -2). Their net CRFs range from -20 to -37 Wm(sup -2). For all-sky, total, and low clouds, the maximum negative net CRFs of -40.1, -70, and -69.5 Wm(sup -2), occur during April; while the respective minimum values of -3.9, -5.7, and -4.6 Wm(sup -2), are found during December. July is the month having maximum negative net CRF of -46.2 Wm(sup -2) for middle clouds, and May has the maximum value of -45.9 Wm(sup -2) for high clouds. An

  2. Effects of environment forcing on marine boundary layer cloud-drizzle processes: MBL Cloud-Drizzle Processes

    SciTech Connect

    Wu, Peng; Dong, Xiquan; Xi, Baike

    Determining the factors affecting drizzle formation in marine boundary layer (MBL) clouds remains a challenge for both observation and modeling communities. To investigate the roles of vertical wind shear and buoyancy (static instability) in drizzle formation, ground-based observations from the Atmospheric Radiation Measurement (ARM) Program at the Azores are analyzed for two types of conditions. The type I clouds should last for at least five hours and more than 90% time must be non-drizzling, and then followed by at least two hours of drizzling periods while the type II clouds are characterized by mesoscale convection cellular (MCC) structures with drizzlemore » occur every two to four hours. By analyzing the boundary layer wind profiles (direction and speed), it was found that either directional or speed shear is required to promote drizzle production in the type I clouds. Observations and a recent model study both suggest that vertical wind shear helps the production of turbulent kinetic energy (TKE), stimulates turbulence within cloud layer, and enhances drizzle formation near the cloud top. The type II clouds do not require strong wind shear to produce drizzle. The small values of lower-tropospheric stability (LTS) and negative Richardson number ( Ri) in the type II cases suggest that boundary layer instability plays an important role in TKE production and cloud-drizzle processes. As a result, by analyzing the relationships between LTS and wind shear for all cases and all time periods, a stronger connection was found between LTS and wind directional shear than that between LTS and wind speed shear.« less

  3. Effects of environment forcing on marine boundary layer cloud-drizzle processes: MBL Cloud-Drizzle Processes

    DOE PAGES

    Wu, Peng; Dong, Xiquan; Xi, Baike; ...

    2017-04-20

    Determining the factors affecting drizzle formation in marine boundary layer (MBL) clouds remains a challenge for both observation and modeling communities. To investigate the roles of vertical wind shear and buoyancy (static instability) in drizzle formation, ground-based observations from the Atmospheric Radiation Measurement (ARM) Program at the Azores are analyzed for two types of conditions. The type I clouds should last for at least five hours and more than 90% time must be non-drizzling, and then followed by at least two hours of drizzling periods while the type II clouds are characterized by mesoscale convection cellular (MCC) structures with drizzlemore » occur every two to four hours. By analyzing the boundary layer wind profiles (direction and speed), it was found that either directional or speed shear is required to promote drizzle production in the type I clouds. Observations and a recent model study both suggest that vertical wind shear helps the production of turbulent kinetic energy (TKE), stimulates turbulence within cloud layer, and enhances drizzle formation near the cloud top. The type II clouds do not require strong wind shear to produce drizzle. The small values of lower-tropospheric stability (LTS) and negative Richardson number ( Ri) in the type II cases suggest that boundary layer instability plays an important role in TKE production and cloud-drizzle processes. As a result, by analyzing the relationships between LTS and wind shear for all cases and all time periods, a stronger connection was found between LTS and wind directional shear than that between LTS and wind speed shear.« less

  4. Incorporation of multiple cloud layers for ultraviolet radiation modeling studies

    NASA Technical Reports Server (NTRS)

    Charache, Darryl H.; Abreu, Vincent J.; Kuhn, William R.; Skinner, Wilbert R.

    1994-01-01

    Cloud data sets compiled from surface observations were used to develop an algorithm for incorporating multiple cloud layers into a multiple-scattering radiative transfer model. Aerosol extinction and ozone data sets were also incorporated to estimate the seasonally averaged ultraviolet (UV) flux reaching the surface of the Earth in the Detroit, Michigan, region for the years 1979-1991, corresponding to Total Ozone Mapping Spectrometer (TOMS) version 6 ozone observations. The calculated UV spectrum was convolved with an erythema action spectrum to estimate the effective biological exposure for erythema. Calculations show that decreasing the total column density of ozone by 1% leads to an increase in erythemal exposure by approximately 1.1-1.3%, in good agreement with previous studies. A comparison of the UV radiation budget at the surface between a single cloud layer method and a multiple cloud layer method presented here is discussed, along with limitations of each technique. With improved parameterization of cloud properties, and as knowledge of biological effects of UV exposure increase, inclusion of multiple cloud layers may be important in accurately determining the biologically effective UV budget at the surface of the Earth.

  5. Detection of Multi-Layer and Vertically-Extended Clouds Using A-Train Sensors

    NASA Technical Reports Server (NTRS)

    Joiner, J.; Vasilkov, A. P.; Bhartia, P. K.; Wind, G.; Platnick, S.; Menzel, W. P.

    2010-01-01

    The detection of mUltiple cloud layers using satellite observations is important for retrieval algorithms as well as climate applications. In this paper, we describe a relatively simple algorithm to detect multiple cloud layers and distinguish them from vertically-extended clouds. The algorithm can be applied to coincident passive sensors that derive both cloud-top pressure from the thermal infrared observations and an estimate of solar photon pathlength from UV, visible, or near-IR measurements. Here, we use data from the A-train afternoon constellation of satellites: cloud-top pressure, cloud optical thickness, the multi-layer flag from the Aqua MODerate-resolution Imaging Spectroradiometer (MODIS) and the optical centroid cloud pressure from the Aura Ozone Monitoring Instrument (OMI). For the first time, we use data from the CloudSat radar to evaluate the results of a multi-layer cloud detection scheme. The cloud classification algorithms applied with different passive sensor configurations compare well with each other as well as with data from CloudSat. We compute monthly mean fractions of pixels containing multi-layer and vertically-extended clouds for January and July 2007 at the OMI spatial resolution (l2kmx24km at nadir) and at the 5kmx5km MODIS resolution used for infrared cloud retrievals. There are seasonal variations in the spatial distribution of the different cloud types. The fraction of cloudy pixels containing distinct multi-layer cloud is a strong function of the pixel size. Globally averaged, these fractions are approximately 20% and 10% for OMI and MODIS, respectively. These fractions may be significantly higher or lower depending upon location. There is a much smaller resolution dependence for fractions of pixels containing vertically-extended clouds (approx.20% for OMI and slightly less for MODIS globally), suggesting larger spatial scales for these clouds. We also find higher fractions of vertically-extended clouds over land as compared with

  6. Vertical Structure of Ice Cloud Layers From CloudSat and CALIPSO Measurements and Comparison to NICAM Simulations

    NASA Technical Reports Server (NTRS)

    Ham, Seung-Hee; Sohn, Byung-Ju; Kato, Seiji; Satoh, Masaki

    2013-01-01

    The shape of the vertical profile of ice cloud layers is examined using 4 months of CloudSat and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) global measurements taken on January, April, July, and October 2007. Ice clouds are selected using temperature profiles when the cloud base is located above the 253K temperature level. The obtained ice water content (IWC), effective radius, or extinction coefficient profiles are normalized by their layer mean values and are expressed in the normalized vertical coordinate, which is defined as 0 and 1 at the cloud base and top heights, respectively. Both CloudSat and CALIPSO observations show that the maximum in the IWC and extinction profiles shifts toward the cloud bottom, as the cloud depth increases. In addition, clouds with a base reaching the surface in a high-latitude region show that the maximum peak of the IWC and extinction profiles occurs near the surface, which is presumably due to snow precipitation. CloudSat measurements show that the seasonal difference in normalized cloud vertical profiles is not significant, whereas the normalized cloud vertical profile significantly varies depending on the cloud type and the presence of precipitation. It is further examined if the 7 day Nonhydrostatic Icosahedral Atmospheric Model (NICAM) simulation results from 25 December 2006 to 1 January 2007 generate similar cloud profile shapes. NICAM IWC profiles also show maximum peaks near the cloud bottom for thick cloud layers and maximum peaks at the cloud bottom for low-level clouds near the surface. It is inferred that oversized snow particles in the NICAM cloud scheme produce a more vertically inhomogeneous IWC profile than observations due to quick sedimentation.

  7. Multi-Layer Arctic Mixed-Phase Clouds Simulated by a Cloud-Resolving Model: Comparison with ARM Observations and Sensitivity Experiments

    NASA Technical Reports Server (NTRS)

    Luo, Yali; Xu, Kuan-Man; Morrison, Hugh; McFarquhar, Greg M.; Wang, Zhien; Zhang, Gong

    2007-01-01

    A cloud-resolving model (CRM) is used to simulate the multiple-layer mixed-phase stratiform (MPS) clouds that occurred during a three-and-a-half day subperiod of the Department of Energy-Atmospheric Radiation Measurement Program s Mixed-Phase Arctic Cloud Experiment (M-PACE). The CRM is implemented with an advanced two-moment microphysics scheme, a state-of-the-art radiative transfer scheme, and a complicated third-order turbulence closure. Concurrent meteorological, aerosol, and ice nucleus measurements are used to initialize the CRM. The CRM is prescribed by time-varying large-scale advective tendencies of temperature and moisture and surface turbulent fluxes of sensible and latent heat. The CRM reproduces the occurrences of the single- and double-layer MPS clouds as revealed by the M-PACE observations. However, the simulated first cloud layer is lower and the second cloud layer thicker compared to observations. The magnitude of the simulated liquid water path agrees with that observed, but its temporal variation is more pronounced than that observed. As in an earlier study of single-layer cloud, the CRM also captures the major characteristics in the vertical distributions and temporal variations of liquid water content (LWC), total ice water content (IWC), droplet number concentration and ice crystal number concentration (nis) as suggested by the aircraft observations. However, the simulated mean values differ significantly from the observed. The magnitude of nis is especially underestimated by one order of magnitude. Sensitivity experiments suggest that the lower cloud layer is closely related to the surface fluxes of sensible and latent heat; the upper cloud layer is probably initialized by the large-scale advective cooling/moistening and maintained through the strong longwave (LW) radiative cooling near the cloud top which enhances the dynamical circulation; artificially turning off all ice-phase microphysical processes results in an increase in LWP by a

  8. 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.

  9. Validation of the Two-Layer Model for Correcting Clear Sky Reflectance Near Clouds

    NASA Technical Reports Server (NTRS)

    Wen, Guoyong; Marshak, Alexander; Evans, K. Frank; Vamal, Tamas

    2014-01-01

    A two-layer model was developed in our earlier studies to estimate the clear sky reflectance enhancement near clouds. This simple model accounts for the radiative interaction between boundary layer clouds and molecular layer above, the major contribution to the reflectance enhancement near clouds for short wavelengths. We use LES/SHDOM simulated 3D radiation fields to valid the two-layer model for reflectance enhancement at 0.47 micrometer. We find: (a) The simple model captures the viewing angle dependence of the reflectance enhancement near cloud, suggesting the physics of this model is correct; and (b) The magnitude of the 2-layer modeled enhancement agree reasonably well with the "truth" with some expected underestimation. We further extend our model to include cloud-surface interaction using the Poisson model for broken clouds. We found that including cloud-surface interaction improves the correction, though it can introduced some over corrections for large cloud albedo, large cloud optical depth, large cloud fraction, large cloud aspect ratio. This over correction can be reduced by excluding scenes (10 km x 10km) with large cloud fraction for which the Poisson model is not designed for. Further research is underway to account for the contribution of cloud-aerosol radiative interaction to the enhancement.

  10. Boundary Layer Thermodynamics and Cloud Microphysics for a Mixed Stratocumulus and Cumulus Cloud Field Observed during ACE-ENA

    NASA Astrophysics Data System (ADS)

    Jensen, M. P.; Miller, M. A.; Wang, J.

    2017-12-01

    The first Intensive Observation Period of the DOE Aerosol and Cloud Experiments in the Eastern North Atlantic (ACE-ENA) took place from 21 June through 20 July 2017 involving the deployment of the ARM Gulfstream-159 (G-1) aircraft with a suite of in situ cloud and aerosol instrumentation in the vicinity of the ARM Climate Research Facility Eastern North Atlantic (ENA) site on Graciosa Island, Azores. Here we present preliminary analysis of the thermodynamic characteristics of the marine boundary layer and the variability of cloud properties for a mixed cloud field including both stratiform cloud layers and deeper cumulus elements. Analysis combines in situ atmospheric state observations from the G-1 with radiosonde profiles and surface meteorology from the ENA site in order to characterize the thermodynamic structure of the marine boundary layer including the coupling state and stability. Cloud/drizzle droplet size distributions measured in situ are combined with remote sensing observations from a scanning cloud radar, and vertically pointing cloud radar and lidar provide quantification of the macrophysical and microphysical properties of the mixed cloud field.

  11. Retrieval of Boundary Layer 3D Cloud Properties Using Scanning Cloud Radar and 3D Radiative Transfer

    SciTech Connect

    Marchand, Roger

    Retrievals of cloud optical and microphysical properties for boundary layer clouds, including those widely used by ASR investigators, frequently assume that clouds are sufficiently horizontally homogeneous that scattering and absorption (at all wavelengths) can be treated using one dimensional (1D) radiative transfer, and that differences in the field-of-view of different sensors are unimportant. Unfortunately, most boundary layer clouds are far from horizontally homogeneous, and numerous theoretical and observational studies show that the assumption of horizontal homogeneity leads to significant errors. The introduction of scanning cloud and precipitation radars at the U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) programmore » sites presents opportunities to move beyond the horizontally homogeneous assumption. The primary objective of this project was to develop a 3D retrieval for warm-phase (liquid only) boundary layer cloud microphysical properties, and to assess errors in current 1D (non-scanning) approaches. Specific research activities also involved examination of the diurnal cycle of hydrometeors as viewed by ARM cloud radar, and continued assessment of precipitation impacts on retrievals of cloud liquid water path using passive microwaves.« less

  12. Cloud and boundary layer interactions over the Arctic sea-ice in late summer

    NASA Astrophysics Data System (ADS)

    Shupe, M. D.; Persson, P. O. G.; Brooks, I. M.; Tjernström, M.; Sedlar, J.; Mauritsen, T.; Sjogren, S.; Leck, C.

    2013-05-01

    Observations from the Arctic Summer Cloud Ocean Study (ASCOS), in the central Arctic sea-ice pack in late summer 2008, provide a detailed view of cloud-atmosphere-surface interactions and vertical mixing processes over the sea-ice environment. Measurements from a suite of ground-based remote sensors, near surface meteorological and aerosol instruments, and profiles from radiosondes and a helicopter are combined to characterize a week-long period dominated by low-level, mixed-phase, stratocumulus clouds. Detailed case studies and statistical analyses are used to develop a conceptual model for the cloud and atmosphere structure and their interactions in this environment. Clouds were persistent during the period of study, having qualities that suggest they were sustained through a combination of advective influences and in-cloud processes, with little contribution from the surface. Radiative cooling near cloud top produced buoyancy-driven, turbulent eddies that contributed to cloud formation and created a cloud-driven mixed layer. The depth of this mixed layer was related to the amount of turbulence and condensed cloud water. Coupling of this cloud-driven mixed layer to the surface boundary layer was primarily determined by proximity. For 75% of the period of study, the primary stratocumulus cloud-driven mixed layer was decoupled from the surface and typically at a warmer potential temperature. Since the near-surface temperature was constrained by the ocean-ice mixture, warm temperatures aloft suggest that these air masses had not significantly interacted with the sea-ice surface. Instead, back trajectory analyses suggest that these warm airmasses advected into the central Arctic Basin from lower latitudes. Moisture and aerosol particles likely accompanied these airmasses, providing necessary support for cloud formation. On the occasions when cloud-surface coupling did occur, back trajectories indicated that these air masses advected at low levels, while mixing

  13. Cloud and boundary layer interactions over the Arctic sea ice in late summer

    NASA Astrophysics Data System (ADS)

    Shupe, M. D.; Persson, P. O. G.; Brooks, I. M.; Tjernström, M.; Sedlar, J.; Mauritsen, T.; Sjogren, S.; Leck, C.

    2013-09-01

    Observations from the Arctic Summer Cloud Ocean Study (ASCOS), in the central Arctic sea-ice pack in late summer 2008, provide a detailed view of cloud-atmosphere-surface interactions and vertical mixing processes over the sea-ice environment. Measurements from a suite of ground-based remote sensors, near-surface meteorological and aerosol instruments, and profiles from radiosondes and a helicopter are combined to characterize a week-long period dominated by low-level, mixed-phase, stratocumulus clouds. Detailed case studies and statistical analyses are used to develop a conceptual model for the cloud and atmosphere structure and their interactions in this environment. Clouds were persistent during the period of study, having qualities that suggest they were sustained through a combination of advective influences and in-cloud processes, with little contribution from the surface. Radiative cooling near cloud top produced buoyancy-driven, turbulent eddies that contributed to cloud formation and created a cloud-driven mixed layer. The depth of this mixed layer was related to the amount of turbulence and condensed cloud water. Coupling of this cloud-driven mixed layer to the surface boundary layer was primarily determined by proximity. For 75% of the period of study, the primary stratocumulus cloud-driven mixed layer was decoupled from the surface and typically at a warmer potential temperature. Since the near-surface temperature was constrained by the ocean-ice mixture, warm temperatures aloft suggest that these air masses had not significantly interacted with the sea-ice surface. Instead, back-trajectory analyses suggest that these warm air masses advected into the central Arctic Basin from lower latitudes. Moisture and aerosol particles likely accompanied these air masses, providing necessary support for cloud formation. On the occasions when cloud-surface coupling did occur, back trajectories indicated that these air masses advected at low levels, while mixing

  14. MPLNET V3 Cloud and Planetary Boundary Layer Detection

    NASA Technical Reports Server (NTRS)

    Lewis, Jasper R.; Welton, Ellsworth J.; Campbell, James R.; Haftings, Phillip C.

    2016-01-01

    The NASA Micropulse Lidar Network Version 3 algorithms for planetary boundary layer and cloud detection are described and differences relative to the previous Version 2 algorithms are highlighted. A year of data from the Goddard Space Flight Center site in Greenbelt, MD consisting of diurnal and seasonal trends is used to demonstrate the results. Both the planetary boundary layer and cloud algorithms show significant improvement of the previous version.

  15. Aerosol-cloud feedbacks in a turbulent environment: Laboratory measurements representative of conditions in boundary layer clouds

    NASA Astrophysics Data System (ADS)

    Cantrell, W. H.; Chandrakar, K. K.; Karki, S.; Kinney, G.; Shaw, R.

    2017-12-01

    Many of the climate impacts of boundary layer clouds are modulated by aerosol particles. As two examples, their interactions with incoming solar and upwelling terrestrial radiation and their propensity for precipitation are both governed by the population of aerosol particles upon which the cloud droplets formed. In turn, clouds are the primary removal mechanism for aerosol particles smaller than a few micrometers and larger than a few nanometers. Aspects of these interconnected phenomena are known in exquisite detail (e.g. Köhler theory), but other parts have not been as amenable to study in the laboratory (e.g. scavenging of aerosol particles by cloud droplets). As a complicating factor, boundary layer clouds are ubiquitously turbulent, which introduces fluctuations in the water vapor concentration and temperature, which govern the saturation ratio which mediates aerosol-cloud interactions. We have performed laboratory measurements of aerosol-cloud coupling and feedbacks, using Michigan Tech's Pi Chamber (Chang et al., 2016). In conditions representative of boundary layer clouds, our data suggest that the lifetime of most interstitial particles in the accumulation mode is governed by cloud activation - particles are removed from the Pi Chamber when they activate and settle out of the chamber as cloud droplets. As cloud droplets are removed, these interstitial particles activate until the initially polluted cloud cleans itself and all particulates are removed from the chamber. At that point, the cloud collapses. Our data also indicate that smaller particles, Dp < ˜ 20 nm are not activated, but are instead removed through diffusion, enhanced by the fact that droplets are moving relative to the suspended aerosol. I will discuss results from both warm (i.e. liquid water only) and mixed phase clouds, showing that cloud and aerosol properties are coupled through fluctuations in the supersaturation, and that threshold behaviors can be defined through the use of the D

  16. Spectral Dependence of MODIS Cloud Droplet Effective Radius Retrievals for Marine Boundary Layer Clouds

    NASA Technical Reports Server (NTRS)

    Zhang, Zhibo; Platnick, Steven E.; Ackerman, Andrew S.; Cho, Hyoun-Myoung

    2014-01-01

    Low-level warm marine boundary layer (MBL) clouds cover large regions of Earth's surface. They have a significant role in Earth's radiative energy balance and hydrological cycle. Despite the fundamental role of low-level warm water clouds in climate, our understanding of these clouds is still limited. In particular, connections between their properties (e.g. cloud fraction, cloud water path, and cloud droplet size) and environmental factors such as aerosol loading and meteorological conditions continue to be uncertain or unknown. Modeling these clouds in climate models remains a challenging problem. As a result, the influence of aerosols on these clouds in the past and future, and the potential impacts of these clouds on global warming remain open questions leading to substantial uncertainty in climate projections. To improve our understanding of these clouds, we need continuous observations of cloud properties on both a global scale and over a long enough timescale for climate studies. At present, satellite-based remote sensing is the only means of providing such observations.

  17. Statistical Analyses of Satellite Cloud Object Data From CERES. Part 4; Boundary-layer Cloud Objects During 1998 El Nino

    NASA Technical Reports Server (NTRS)

    Xu, Kuan-Man; Wong, Takmeng; Wielicki, Bruce A.; Parker, Lindsay

    2006-01-01

    Three boundary-layer cloud object types, stratus, stratocumulus and cumulus, that occurred over the Pacific Ocean during January-August 1998, are identified from the CERES (Clouds and the Earth s Radiant Energy System) single scanner footprint (SSF) data from the TRMM (Tropical Rainfall Measuring Mission) satellite. This study emphasizes the differences and similarities in the characteristics of each cloud-object type between the tropical and subtropical regions and among different size categories and among small geographic areas. Both the frequencies of occurrence and statistical distributions of cloud physical properties are analyzed. In terms of frequencies of occurrence, stratocumulus clouds dominate the entire boundary layer cloud population in all regions and among all size categories. Stratus clouds are more prevalent in the subtropics and near the coastal regions, while cumulus clouds are relatively prevalent over open ocean and the equatorial regions, particularly, within the small size categories. The largest size category of stratus cloud objects occurs more frequently in the subtropics than in the tropics and has much larger average size than its cumulus and stratocumulus counterparts. Each of the three cloud object types exhibits small differences in statistical distributions of cloud optical depth, liquid water path, TOA albedo and perhaps cloud-top height, but large differences in those of cloud-top temperature and OLR between the tropics and subtropics. Differences in the sea surface temperature (SST) distributions between the tropics and subtropics influence some of the cloud macrophysical properties, but cloud microphysical properties and albedo for each cloud object type are likely determined by (local) boundary-layer dynamics and structures. Systematic variations of cloud optical depth, TOA albedo, cloud-top height, OLR and SST with cloud object sizes are pronounced for the stratocumulus and stratus types, which are related to systematic

  18. Ice Cloud Formation and Dehydration in the Tropical Tropopause Layer

    NASA Technical Reports Server (NTRS)

    Jensen, Eric; Pfister, Leonhard; Gore, Warren J. (Technical Monitor)

    2002-01-01

    Stratospheric water vapor is important not only for its greenhouse forcing, but also because it plays a significant role in stratospheric chemistry. several recent studies have focused on the potential for dehydration due to ice cloud formation in air rising slowly through the tropical tropopause layer. Holton and Gettelman showed that temperature variations associated with horizontal transport of air in the tropopause layer can drive ice cloud formation and dehydration, and Gettelman et al. recently examined the cloud formation and dehydration along kinematic trajectories using simple assumptions about the cloud properties. In this study, we use a Lagrangian, one-dimensional cloud model to further investigate cloud formation and dehydration as air is transported horizontally and vertically through the tropical tropopause layer. Time-height curtains of temperature are extracted from meteorological analyses. The model tracks the growth and sedimentation of individual cloud particles. The regional distribution of clouds simulated in the model is comparable to the subvisible cirrus distribution indicated by SAGE II. The simulated cloud properties depend strongly on the assumed ice supersaturation threshold for ice nucleation. with effective nuclei present (low supersaturation threshold), ice number densities are high (0.1--10 cm(circumflex)-3), and ice crystals do not grow large enough to fall very far, resulting in limited dehydration. With higher supersaturation thresholds, ice number densities are much lower (less than 0.01 cm(circumflex)-3), and ice crystals grow large enough to fall substantially; however, supersaturated air often crosses the tropopause without cloud formation. The clouds typically do not dehydrate the air along trajectories down to the temperature minimum saturation mixing ratio. Rather the water vapor mixing ratio crossing the tropopause along trajectories is typically 10-50% larger than the saturation mixing ratio.

  19. Effects of Environment Forcing on Marine Boundary Layer Cloud-Drizzle Processes

    NASA Astrophysics Data System (ADS)

    Dong, X.

    2017-12-01

    Determining the factors affecting drizzle formation in marine boundary layer (MBL) clouds remains a challenge for both observation and modeling communities. To investigate the roles of vertical wind shear and buoyancy (static instability) in drizzle formation, ground-based observations from the Atmospheric Radiation Measurement (ARM) Program at the Azores are analyzed for two types of conditions. The type I clouds should last for at least five hours and more than 90% time must be non-drizzling, and then followed by at least two hours of drizzling periods while the type II clouds are characterized by mesoscale convection cellular (MCC) structures with drizzle occur every two to four hours. By analyzing the boundary layer wind profiles (direction and speed), it was found that either directional or speed shear is required to promote drizzle production in the type I clouds. Observations and a recent model study both suggest that vertical wind shear helps the production of turbulent kinetic energy (TKE), stimulates turbulence within cloud layer, and enhances drizzle formation near the cloud top. The type II clouds do not require strong wind shear to produce drizzle. The small values of lower-tropospheric stability (LTS) and negative Richardson number (Ri) in the type II cases suggest that boundary layer instability plays an important role in TKE production and cloud-drizzle processes. By analyzing the relationships between LTS and wind shear for all cases and all time periods, a stronger connection was found between LTS and wind directional shear than that between LTS and wind speed shear.

  20. Cumulus cloud venting of mixed layer ozone

    NASA Technical Reports Server (NTRS)

    Ching, J. K. S.; Shipley, S. T.; Browell, E. V.; Brewer, D. A.

    1985-01-01

    Observations are presented which substantiate the hypothesis that significant vertical exchange of ozone and aerosols occurs between the mixed layer and the free troposphere during cumulus cloud convective activity. The experiments utilized the airborne Ultra-Violet Differential Absorption Lidar (UV-DIAL) system. This system provides simultaneous range resolved ozone concentration and aerosol backscatter profiles with high spatial resolution. Evening transects were obtained in the downwind area where the air mass had been advected. Space-height analyses for the evening flight show the cloud debris as patterns of ozone typically in excess of the ambient free tropospheric background. This ozone excess was approximately the value of the concentration difference between the mixed layer and free troposphere determined from independent vertical soundings made by another aircraft in the afternoon.

  1. Marine Layer Clouds off the California Coast

    NASA Image and Video Library

    2017-12-08

    NASA image acquired September 27, 2012 On September 27, 2012, the Visible Infrared Imaging Radiometer Suite (VIIRS) on the Suomi NPP satellite captured this nighttime view of low-lying marine layer clouds along the coast of California. The image was captured by the VIIRS “day-night band,” which detects light in a range of wavelengths from green to near-infrared and uses filtering techniques to observe signals such as gas flares, auroras, wildfires, city lights, and reflected moonlight. An irregularly-shaped patch of high clouds hovers off the coast of California, and moonlight caused the high clouds to cast distinct shadows on the marine layer clouds below. VIIRS acquired the image when the Moon was in its waxing gibbous phase, meaning it was more than half-lit, but less than full. Low clouds pose serious hazards for air and ship traffic, but satellites have had difficulty detecting them in the past. To illustrate this, the second image shows the same scene in thermal infrared, the band that meteorologists generally use to monitor clouds at night. Only high clouds are visible; the low clouds do not show up at all because they are roughly the same temperature as the ground. NASA Earth Observatory image by Jesse Allen and Robert Simmon, using VIIRS Day-Night Band data from the Suomi National Polar-orbiting Partnership. Suomi NPP is the result of a partnership between NASA, the National Oceanic and Atmospheric Administration, and the Department of Defense. Caption by Adam Voiland. Instrument: Suomi NPP - VIIRS Credit: NASA Earth Observatory Click here to view all of the Earth at Night 2012 images Click here to read more about this image NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission

  2. A General Cross-Layer Cloud Scheduling Framework for Multiple IoT Computer Tasks.

    PubMed

    Wu, Guanlin; Bao, Weidong; Zhu, Xiaomin; Zhang, Xiongtao

    2018-05-23

    The diversity of IoT services and applications brings enormous challenges to improving the performance of multiple computer tasks' scheduling in cross-layer cloud computing systems. Unfortunately, the commonly-employed frameworks fail to adapt to the new patterns on the cross-layer cloud. To solve this issue, we design a new computer task scheduling framework for multiple IoT services in cross-layer cloud computing systems. Specifically, we first analyze the features of the cross-layer cloud and computer tasks. Then, we design the scheduling framework based on the analysis and present detailed models to illustrate the procedures of using the framework. With the proposed framework, the IoT services deployed in cross-layer cloud computing systems can dynamically select suitable algorithms and use resources more effectively to finish computer tasks with different objectives. Finally, the algorithms are given based on the framework, and extensive experiments are also given to validate its effectiveness, as well as its superiority.

  3. Overview of Boundary Layer Clouds Using Satellite and Ground-Based Measurements

    NASA Astrophysics Data System (ADS)

    Xi, B.; Dong, X.; Wu, P.; Qiu, S.

    2017-12-01

    A comprehensive summary of boundary layer clouds properties based on our few recently studies will be presented. The analyses include the global cloud fractions and cloud macro/micro- physical properties based on satellite measurements using both CERES-MODIS and CloudSat/Caliposo data products,; the annual/seasonal/diurnal variations of stratocumulus clouds over different climate regions (mid-latitude land, mid-latitude ocean, and Arctic region) using DOE ARM ground-based measurements over Southern great plain (SGP), Azores (GRW), and North slope of Alaska (NSA) sites; the impact of environmental conditions to the formation and dissipation process of marine boundary layer clouds over Azores site; characterizing Arctice mixed-phase cloud structure and favorable environmental conditions for the formation/maintainess of mixed-phase clouds over NSA site. Though the presentation has widely spread topics, we will focus on the representation of the ground-based measurements over different climate regions; evaluation of satellite retrieved cloud properties using these ground-based measurements, and understanding the uncertainties of both satellite and ground-based retrievals and measurements.

  4. Cloud-Scale Numerical Modeling of the Arctic Boundary Layer

    NASA Technical Reports Server (NTRS)

    Krueger, Steven K.

    1998-01-01

    The interactions between sea ice, open ocean, atmospheric radiation, and clouds over the Arctic Ocean exert a strong influence on global climate. Uncertainties in the formulation of interactive air-sea-ice processes in global climate models (GCMs) result in large differences between the Arctic, and global, climates simulated by different models. Arctic stratus clouds are not well-simulated by GCMs, yet exert a strong influence on the surface energy budget of the Arctic. Leads (channels of open water in sea ice) have significant impacts on the large-scale budgets during the Arctic winter, when they contribute about 50 percent of the surface fluxes over the Arctic Ocean, but cover only 1 to 2 percent of its area. Convective plumes generated by wide leads may penetrate the surface inversion and produce condensate that spreads up to 250 km downwind of the lead, and may significantly affect the longwave radiative fluxes at the surface and thereby the sea ice thickness. The effects of leads and boundary layer clouds must be accurately represented in climate models to allow possible feedbacks between them and the sea ice thickness. The FIRE III Arctic boundary layer clouds field program, in conjunction with the SHEBA ice camp and the ARM North Slope of Alaska and Adjacent Arctic Ocean site, will offer an unprecedented opportunity to greatly improve our ability to parameterize the important effects of leads and boundary layer clouds in GCMs.

  5. Toward low-cloud-permitting cloud superparameterization with explicit boundary layer turbulence

    NASA Astrophysics Data System (ADS)

    Parishani, Hossein; Pritchard, Michael S.; Bretherton, Christopher S.; Wyant, Matthew C.; Khairoutdinov, Marat

    2017-07-01

    Systematic biases in the representation of boundary layer (BL) clouds are a leading source of uncertainty in climate projections. A variation on superparameterization (SP) called "ultraparameterization" (UP) is developed, in which the grid spacing of the cloud-resolving models (CRMs) is fine enough (250 × 20 m) to explicitly capture the BL turbulence, associated clouds, and entrainment in a global climate model capable of multiyear simulations. UP is implemented within the Community Atmosphere Model using 2° resolution (˜14,000 embedded CRMs) with one-moment microphysics. By using a small domain and mean-state acceleration, UP is computationally feasible today and promising for exascale computers. Short-duration global UP hindcasts are compared with SP and satellite observations of top-of-atmosphere radiation and cloud vertical structure. The most encouraging improvement is a deeper BL and more realistic vertical structure of subtropical stratocumulus (Sc) clouds, due to stronger vertical eddy motions that promote entrainment. Results from 90 day integrations show climatological errors that are competitive with SP, with a significant improvement in the diurnal cycle of offshore Sc liquid water. Ongoing concerns with the current UP implementation include a dim bias for near-coastal Sc that also occurs less prominently in SP and a bright bias over tropical continental deep convection zones. Nevertheless, UP makes global eddy-permitting simulation a feasible and interesting alternative to conventionally parameterized GCMs or SP-GCMs with turbulence parameterizations for studying BL cloud-climate and cloud-aerosol feedback.

  6. Durable superhydrophobic surfaces made by intensely connecting a bipolar top layer to the substrate with a middle connecting layer.

    PubMed

    Zhi, Jinghui; Zhang, Li-Zhi

    2017-08-30

    This study reported a simple fabrication method for a durable superhydrophobic surface. The superhydrophobic top layer of the durable superhydrophobic surface was connected intensely to the substrate through a middle connecting layer. Glycidoxypropyltrimethoxysilane (KH-560) after hydrolysis was used to obtain a hydrophilic middle connecting layer. It could be adhered to the hydrophilic substrate by covalent bonds. Ring-open reaction with octadecylamine let the KH-560 middle layer form a net-like structure. The net-like sturcture would then encompass and station the silica particles that were used to form the coarse micro structures, intensely to increase the durability. The top hydrophobic layer with nano-structures was formed on the KH-560 middle layer. It was obtained by a bipolar nano-silica solution modified by hexamethyldisilazane (HMDS). This layer was connected to the middle layer intensely by the polar Si hydroxy groups, while the non-polar methyl groups on the surface, accompanied by the micro and nano structures, made the surface rather hydrophobic. The covalently interfacial interactions between the substrate and the middle layer, and between the middle layer and the top layer, strengthened the durability of the superhydrophobic surface. The abrasion test results showed that the superhydrophobic surface could bear 180 abrasion cycles on 1200 CW sandpaper under 2 kPa applied pressure.

  7. Toward low-cloud-permitting cloud superparameterization with explicit boundary layer turbulence

    SciTech Connect

    Parishani, Hossein; Pritchard, Michael S.; Bretherton, Christopher S.

    Systematic biases in the representation of boundary layer (BL) clouds are a leading source of uncertainty in climate projections. A variation on superparameterization (SP) called “ultraparameterization” (UP) is developed, in which the grid spacing of the cloud-resolving models (CRMs) is fine enough (250 × 20 m) to explicitly capture the BL turbulence, associated clouds, and entrainment in a global climate model capable of multiyear simulations. UP is implemented within the Community Atmosphere Model using 2° resolution (~14,000 embedded CRMs) with one-moment microphysics. By using a small domain and mean-state acceleration, UP is computationally feasible today and promising for exascale computers.more » Short-duration global UP hindcasts are compared with SP and satellite observations of top-of-atmosphere radiation and cloud vertical structure. The most encouraging improvement is a deeper BL and more realistic vertical structure of subtropical stratocumulus (Sc) clouds, due to stronger vertical eddy motions that promote entrainment. Results from 90 day integrations show climatological errors that are competitive with SP, with a significant improvement in the diurnal cycle of offshore Sc liquid water. Ongoing concerns with the current UP implementation include a dim bias for near-coastal Sc that also occurs less prominently in SP and a bright bias over tropical continental deep convection zones. Nevertheless, UP makes global eddy-permitting simulation a feasible and interesting alternative to conventionally parameterized GCMs or SP-GCMs with turbulence parameterizations for studying BL cloud-climate and cloud-aerosol feedback.« less

  8. Toward low-cloud-permitting cloud superparameterization with explicit boundary layer turbulence

    DOE PAGES

    Parishani, Hossein; Pritchard, Michael S.; Bretherton, Christopher S.; ...

    2017-06-19

    Systematic biases in the representation of boundary layer (BL) clouds are a leading source of uncertainty in climate projections. A variation on superparameterization (SP) called “ultraparameterization” (UP) is developed, in which the grid spacing of the cloud-resolving models (CRMs) is fine enough (250 × 20 m) to explicitly capture the BL turbulence, associated clouds, and entrainment in a global climate model capable of multiyear simulations. UP is implemented within the Community Atmosphere Model using 2° resolution (~14,000 embedded CRMs) with one-moment microphysics. By using a small domain and mean-state acceleration, UP is computationally feasible today and promising for exascale computers.more » Short-duration global UP hindcasts are compared with SP and satellite observations of top-of-atmosphere radiation and cloud vertical structure. The most encouraging improvement is a deeper BL and more realistic vertical structure of subtropical stratocumulus (Sc) clouds, due to stronger vertical eddy motions that promote entrainment. Results from 90 day integrations show climatological errors that are competitive with SP, with a significant improvement in the diurnal cycle of offshore Sc liquid water. Ongoing concerns with the current UP implementation include a dim bias for near-coastal Sc that also occurs less prominently in SP and a bright bias over tropical continental deep convection zones. Nevertheless, UP makes global eddy-permitting simulation a feasible and interesting alternative to conventionally parameterized GCMs or SP-GCMs with turbulence parameterizations for studying BL cloud-climate and cloud-aerosol feedback.« less

  9. Joint retrievals of cloud and drizzle in marine boundary layer clouds using ground-based radar, lidar and zenith radiances

    DOE PAGES

    Fielding, M. D.; Chiu, J. C.; Hogan, R. J.; ...

    2015-02-16

    Active remote sensing of marine boundary-layer clouds is challenging as drizzle drops often dominate the observed radar reflectivity. We present a new method to simultaneously retrieve cloud and drizzle vertical profiles in drizzling boundary-layer cloud using surface-based observations of radar reflectivity, lidar attenuated backscatter, and zenith radiances. Specifically, the vertical structure of droplet size and water content of both cloud and drizzle is characterised throughout the cloud. An ensemble optimal estimation approach provides full error statistics given the uncertainty in the observations. To evaluate the new method, we first perform retrievals using synthetic measurements from large-eddy simulation snapshots of cumulusmore » under stratocumulus, where cloud water path is retrieved with an error of 31 g m −2. The method also performs well in non-drizzling clouds where no assumption of the cloud profile is required. We then apply the method to observations of marine stratocumulus obtained during the Atmospheric Radiation Measurement MAGIC deployment in the northeast Pacific. Here, retrieved cloud water path agrees well with independent 3-channel microwave radiometer retrievals, with a root mean square difference of 10–20 g m −2.« less

  10. Large Eddy Simulations of Continental Boundary Layer Clouds Observed during the RACORO Field Campaign

    NASA Astrophysics Data System (ADS)

    Endo, S.; Fridlind, A. M.; Lin, W.; Vogelmann, A. M.; Toto, T.; Liu, Y.

    2013-12-01

    Three cases of boundary layer clouds are analyzed in the FAst-physics System TEstbed and Research (FASTER) project, based on continental boundary-layer-cloud observations during the RACORO Campaign [Routine Atmospheric Radiation Measurement (ARM) Aerial Facility (AAF) Clouds with Low Optical Water Depths (CLOWD) Optical Radiative Observations] at the ARM Climate Research Facility's Southern Great Plains (SGP) site. The three 60-hour case study periods are selected to capture the temporal evolution of cumulus, stratiform, and drizzling boundary-layer cloud systems under a range of conditions, intentionally including those that are relatively more mixed or transitional in nature versus being of a purely canonical type. Multi-modal and temporally varying aerosol number size distribution profiles are derived from aircraft observations. Large eddy simulations (LESs) are performed for the three case study periods using the GISS Distributed Hydrodynamic Aerosol and Radiative Modeling Application (DHARMA) model and the WRF-FASTER model, which is the Weather Research and Forecasting (WRF) model implemented with forcing ingestion and other functions to constitute a flexible LES. The two LES models commonly capture the significant transitions of cloud-topped boundary layers in the three periods: diurnal evolution of cumulus layers repeating over multiple days, nighttime evolution/daytime diminution of thick stratus, and daytime breakup of stratus and stratocumulus clouds. Simulated transitions of thermodynamic structures of the cloud-topped boundary layers are examined by balloon-borne soundings and ground-based remote sensors. Aircraft observations are then used to statistically evaluate the predicted cloud droplet number size distributions under varying aerosol and cloud conditions. An ensemble approach is used to refine the model configuration for the combined use of observations with parallel LES and single-column model simulations. See Lin et al. poster for single

  11. Remote Sensing of Multiple Cloud Layer Heights Using Multi-Angular Measurements

    NASA Technical Reports Server (NTRS)

    Sinclair, Kenneth; Van Diedenhoven, Bastiaan; Cairns, Brian; Yorks, John; Wasilewski, Andrzej; Mcgill, Matthew

    2017-01-01

    Cloud top height (CTH) affects the radiative properties of clouds. Improved CTH observations will allow for improved parameterizations in large-scale models and accurate information on CTH is also important when studying variations in freezing point and cloud microphysics. NASAs airborne Research Scanning Polarimeter (RSP) is able to measure cloud top height using a novel multi-angular contrast approach. For the determination of CTH, a set of consecutive nadir reflectances is selected and the cross-correlations between this set and co-located sets at other viewing angles are calculated for a range of assumed cloud top heights, yielding a correlation profile. Under the assumption that cloud reflectances are isotropic, local peaks in the correlation profile indicate cloud layers. This technique can be applied to every RSP footprint and we demonstrate that detection of multiple peaks in the correlation profile allow retrieval of heights of multiple cloud layers within single RSP footprints. This paper provides an in-depth description of the architecture and performance of the RSPs CTH retrieval technique using data obtained during the Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC(exp. 4)RS) campaign. RSP retrieved cloud heights are evaluated using collocated data from the Cloud Physics Lidar (CPL). The method's accuracy associated with the magnitude of correlation, optical thickness, cloud thickness and cloud height are explored. The technique is applied to measurements at a wavelength of 670 nm and 1880 nm and their combination. The 1880-nm band is virtually insensitive to the lower troposphere due to strong water vapor absorption.

  12. Single-Column Model Simulations of Subtropical Marine Boundary-Layer Cloud Transitions Under Weakening Inversions: SCM SIMULATIONS OF CLOUD TRANSITIONS

    SciTech Connect

    Neggers, R. A. J.; Ackerman, A. S.; Angevine, W. M.

    Results are presented of the GASS/EUCLIPSE single-column model inter-comparison study on the subtropical marine low-level cloud transition. A central goal is to establish the performance of state-of-the-art boundary-layer schemes for weather and climate mod- els for this cloud regime, using large-eddy simulations of the same scenes as a reference. A novelty is that the comparison covers four different cases instead of one, in order to broaden the covered parameter space. Three cases are situated in the North-Eastern Pa- cific, while one reflects conditions in the North-Eastern Atlantic. A set of variables is considered that reflects key aspects of the transitionmore » process, making use of simple met- rics to establish the model performance. Using this method some longstanding problems in low level cloud representation are identified. Considerable spread exists among models concerning the cloud amount, its vertical structure and the associated impact on radia- tive transfer. The sign and amplitude of these biases differ somewhat per case, depending on how far the transition has progressed. After cloud breakup the ensemble median ex- hibits the well-known “too few too bright” problem. The boundary layer deepening rate and its state of decoupling are both underestimated, while the representation of the thin capping cloud layer appears complicated by a lack of vertical resolution. Encouragingly, some models are successful in representing the full set of variables, in particular the verti- cal structure and diurnal cycle of the cloud layer in transition. An intriguing result is that the median of the model ensemble performs best, inspiring a new approach in subgrid pa- rameterization.« less

  13. 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.

  14. First UAV Measurements of Entrainment Layer Fluxes with Coupled Cloud Property Measurements

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

    This study details entrainment flux measurements made from a lightweight unmanned aerial vehicle (UAV) containing turbulent water vapor flux instrumentation (Thomas et al., 2012). The system was flown for 26 flights during the Cloud, Aerosol, Radiative forcing, Dynamics EXperiment (CARDEX) in the Maldives in March 2012 to study interrelationships between entrainment, aerosols, water budget, cloud microphysics and radiative fluxes in a trade wind cumulus cloud regime. A major advantage of using this lightweight, precision autopiloted UAV system with scientific telemetry is the ability to target small-scale features in the boundary layer, such as an entrainment layer, with minimal aircraft induced disruption. Results are presented from two UAVs flown in stacked formation: one UAV situated in-cloud measuring cloud-droplet size distribution spectra and liquid water content, and another co-located 100m above measuring turbulent properties and entrainment latent heat flux (λEE). We also show latent heat flux and turbulence measurements routinely made at the entrainment layer base and altitudes from the surface up to 4kft. Ratios of λEE to corresponding surface tower values (λES) display a bimodal frequency distribution with ranges 0.22-0.53 and 0.79-1.5, with occasional events >7. Reasons for this distribution are discussed drawing upon boundary layer and free tropospheric dynamics and meteorology, turbulence length scales, surface conditions, and cloud interactions. Latent heat flux profiles are combined with in-cloud UAV Liquid Water Content (LWC) data and surface based Liquid Water Path (LWP) and Precipitable Water Vapor (PWV) measurements to produce observationally constrained vertical water budgets, providing insights into diurnal coupling of λEE and λES. Observed λEE, λES, water budgets, and cloud microphysical responses to entrainment are then contextualized with respect to measured aerosol loading profiles and airmass history.

  15. Ultra-clean Layers (UCLs) and Low Albedo Clouds ("gray clouds") in the Marine Boundary Layer - CSET aircraft data, 2-D bin spectral cloud parcel model, large eddy simulation and satellite observations from CALIPSO, MODIS and COSMIC

    NASA Astrophysics Data System (ADS)

    O, K. T.; Wood, R.; Bretherton, C. S.; Eastman, R. M.; Tseng, H. H.

    2016-12-01

    During the 2015 Cloud System Evolution in the Trades (CSET) field program (CSET, Jul-Aug 2015, subtropical NE Pacific), the NSF/NCAR G-V aircraft frequently encountered ultra clean layers (hereafter UCLs) with extremely low accumulation mode aerosol (i.e. diameter da> 100nm) concentration (hereafter Na), and low albedo ( 0.2) warm clouds (termed "gray clouds" in our study) with low droplet concentration (hereafter Nd). The analysis of CSET aircraft data shows that (1) UCLs and gray clouds are mostly commonly found at a height of 1.5-2km, typically close to the top of the MBL, (2) UCLs and gray cloud coverage as high as 40-60% between 135W and 155W (i.e. Sc-Cu transition region) but occur very infrequently east of 130W (i.e. shallow, near-coastal stratocumulus region), and (3) UCLs and gray clouds exhibit remarkably low turbulence compared with non-UCL clear sky and clouds. It should be noted that most previous aircraft sampling of low clouds occurred close to the Californian coast, so the prevalence of UCLs and gray clouds has not been previously noted. Based on the analysis of aircraft data, we hypothesize that gray clouds result from detrainment of cloud close to the top of precipitating trade cumuli, and UCLs are remnants of these layers when gray clouds evaporates. The simulations in our study are performed using 2-D bin spectral cloud parcel model and version 6.9 of the System for Atmospheric Modeling (SAM). Our idealized simulations suggest that collision-coalescence plays a crucial role in reducing Nd such that gray clouds can easily form via collision-coalescence in layers detrained from the cloud top at trade cumulus regime, but can not form at stratocumulus regime. Upon evaporation of gray clouds, only few accumulation mode aerosols are returned to the clear sky, leaving horizontally-extensive UCLs (i.e. clean clear sky). Analysis of CSET flight data and idealized model simulations both suggest cloud top/PBL height may play an important role in the

  16. Joint retrievals of cloud and drizzle in marine boundary layer clouds using ground-based radar, lidar and zenith radiances

    DOE PAGES

    Fielding, M. D.; Chiu, J. C.; Hogan, R. J.; ...

    2015-07-02

    Active remote sensing of marine boundary-layer clouds is challenging as drizzle drops often dominate the observed radar reflectivity. We present a new method to simultaneously retrieve cloud and drizzle vertical profiles in drizzling boundary-layer clouds using surface-based observations of radar reflectivity, lidar attenuated backscatter, and zenith radiances under conditions when precipitation does not reach the surface. Specifically, the vertical structure of droplet size and water content of both cloud and drizzle is characterised throughout the cloud. An ensemble optimal estimation approach provides full error statistics given the uncertainty in the observations. To evaluate the new method, we first perform retrievalsmore » using synthetic measurements from large-eddy simulation snapshots of cumulus under stratocumulus, where cloud water path is retrieved with an error of 31 g m -2. The method also performs well in non-drizzling clouds where no assumption of the cloud profile is required. We then apply the method to observations of marine stratocumulus obtained during the Atmospheric Radiation Measurement MAGIC deployment in the Northeast Pacific. Here, retrieved cloud water path agrees well with independent three-channel microwave radiometer retrievals, with a root mean square difference of 10–20 g m -2.« less

  17. Influence of Subpixel Scale Cloud Top Structure on Reflectances from Overcast Stratiform Cloud Layers

    NASA Technical Reports Server (NTRS)

    Loeb, N. G.; Varnai, Tamas; Winker, David M.

    1998-01-01

    Recent observational studies have shown that satellite retrievals of cloud optical depth based on plane-parallel model theory suffer from systematic biases that depend on viewing geometry, even when observations are restricted to overcast marine stratus layers, arguably the closest to plane parallel in nature. At moderate to low sun elevations, the plane-parallel model significantly overestimates the reflectance dependence on view angle in the forward-scattering direction but shows a similar dependence in the backscattering direction. Theoretical simulations are performed that show that the likely cause for this discrepancy is because the plane-parallel model assumption does not account for subpixel, scale variations in cloud-top height (i.e., "cloud bumps"). Monte Carlo simulation, comparing ID model radiances to radiances from overcast cloud field with 1) cloud-top height variation, but constant cloud volume extinction; 2) flat tops but horizontal variations in cloud volume extinction; and 3) variations in both cloud top height and cloud extinction are performed over a approximately equal to 4 km x 4 km domain (roughly the size of an individual GAC AVHRR pixel). The comparisons show that when cloud-top height variations are included, departures from 1D theory are remarkably similar (qualitatively) to those obtained observationally. In contrast, when clouds are assumed flat and only cloud extinction is variable, reflectance differences are much smaller and do not show any view-angle dependence. When both cloud-top height and cloud extinction variations are included, however, large increases in cloud extinction variability can enhance reflectance difference. The reason 3D-1D reflectance differences are more sensitive to cloud-top height variations in the forward-scattering direction (at moderate to low, sun elevations) is because photons leaving the cloud field in that direction experience fewer scattering events (low-order scattering) and are restricted to the

  18. Above-Cloud Precipitable Water Retrievals using the MODIS 0.94 micron Band with Applications for Multi-Layer Cloud Detection

    NASA Technical Reports Server (NTRS)

    Platnick, S.; Wind, G.

    2004-01-01

    In order to perform satellite retrievals of cloud properties, it is important to account for the effect of the above-cloud atmosphere on the observations. The solar bands used in the operational MODIS Terra and Aqua cloud optical and microphysical algorithms (visible, NIR, and SWIR spectral windows) are primarily affected by water vapor, and to a lesser extent by well-mixed gases. For water vapor, the above-cloud column amount, or precipitable water, provides adequate information for an atmospheric correction; details of the vertical vapor distribution are not typically necessary for the level of correction required. Cloud-top pressure has a secondary effect due to pressure broadening influences. For well- mixed gases, cloud-top pressure is also required for estimates of above-cloud abundances. We present a method for obtaining above-cloud precipitable water over dark Ocean surfaces using the MODIS 0.94 pm vapor absorption band. The retrieval includes an iterative procedure for establishing cloud-top temperature and pressure, and is useful for both single layer water and ice clouds. Knowledge of cloud thermodynamic phase is fundamental in retrieving cloud optical and microphysical properties. However, in cases of optically thin cirrus overlapping lower water clouds, the concept of a single unique phase is ill- defined and depends, at least, on the spectral region of interest. We will present a method for multi-layer and multi-phase cloud detection which uses above-cloud precipitable water retrievals along with several existing MODIS operational cloud products (cloud-top pressure derived from a C02 slicing algorithm, IR and SWIR phase retrievals). Results are catagorized by whether the radiative signature in the MODIS solar bands is primarily that of a water cloud with ice cloud contamination, or visa-versa. Examples in polar and mid-latitude regions will be shown.

  19. Observations of high droplet number concentrations in Southern Ocean boundary layer clouds

    NASA Astrophysics Data System (ADS)

    Chubb, T.; Huang, Y.; Jensen, J.; Campos, T.; Siems, S.; Manton, M.

    2015-09-01

    Data from the standard cloud physics payload during the NSF/NCAR High-performance Instrumented Airborne Platform for Environmental Research (HIAPER) Pole-to-Pole Observations (HIPPO) campaigns provide a snapshot of unusual wintertime microphysical conditions in the boundary layer over the Southern Ocean. On 29 June 2011, the HIAPER sampled the boundary layer in a region of pre-frontal warm air advection between 58 and 48° S to the south of Tasmania. Cloud droplet number concentrations were consistent with climatological values in the northernmost profiles but were exceptionally high for wintertime in the Southern Ocean at 100-200 cm-3 in the southernmost profiles. Sub-micron (0.06cloud droplet concentration in the boundary layer. Instead, the gale force surface winds in this case (wind speed at 167 m above sea level was >25 m s-1) were most likely responsible for production of sea spray aerosol which influenced the microphysical properties of the boundary layer clouds. The smaller size and higher number concentration of cloud droplets is inferred to increase the albedo of these clouds, and these conditions occur regularly, and are expected to increase in frequency, over windy parts of the Southern Ocean.

  20. Modeling of Shallow Marine Cloud Topped Boundary Layer

    NASA Astrophysics Data System (ADS)

    Janjic, Z.

    2017-12-01

    A common problem in many atmospheric models is excessive expansion over cold water of shallow marine planetary boundary layer (PBL) topped by a thin cloud layer. This phenomenon is often accompanied by spurious light precipitation. The "Cloud Top Entrainment Instability" (CTEI) was proposed as an explanation of the mechanism controlling this process and thus preventing spurious enlargement of the cloudy area and widely spread light precipitation observed in the models. A key element of this hypothesis is evaporative cooling at the PBL top. However, the CTEI hypothesis remains controversial. For example, a recent direct simulation experiment indicated that the evaporative cooling couldn't explain the break-up of the cloudiness as hypothesized by the CTEI. Here, it is shown that the cloud break-up can be achieved in numerical models by a further modification of the nonsingular implementation of the nonsingular Mellor-Yamada Level 2.5 turbulence closure model (MYJ) developed at the National Centers for Environmental Prediction (NCEP) Washington. Namely, the impact of moist convective instability is included into the turbulent energy production/dissipation equation if (a) the stratification is stable, (b) the lifting condensation level (LCL) for a particle starting at a model level is below the next upper model level, and (c) there is enough turbulent kinetic energy so that, due to random vertical turbulent motions, a particle starting from a model level can reach its LCL. The criterion (c) should be sufficiently restrictive because otherwise the cloud cover can be completely removed. A real data example will be shown demonstrating the ability of the method to break the spurious cloud cover during the day, but also to allow its recovery over night.

  1. Seasonally Transported Aerosol Layers Over Southeast Atlantic are Closer to Underlying Clouds than Previously Reported

    NASA Technical Reports Server (NTRS)

    Rajapakshe, Chamara; Zhang, Zhibo; Yorks, John E.; Yu, Hongbin; Tan, Qian; Meyer, Kerry; Platnick, Steven; Winker, David M.

    2017-01-01

    From June to October, low-level clouds in the southeast (SE) Atlantic often underlie seasonal aerosol layers transported from African continent. Previously, the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) 532 nm lidar observations have been used to estimate the relative vertical location of the above-cloud aerosols (ACA) to the underlying clouds. Here we show new observations from NASA's Cloud-Aerosol Transport System (CATS) lidar. Two seasons of CATS 1064 nm observations reveal that the bottom of the ACA layer is much lower than previously estimated based on CALIPSO 532 nm observations. For about 60% of CATS nighttime ACA scenes, the aerosol layer base is within 360 m distance to the top of the underlying cloud. Our results are important for future studies of the microphysical indirect and semidirect effects of ACA in the SE Atlantic region.

  2. Observation of Upper and Middle Tropospheric Clouds

    NASA Technical Reports Server (NTRS)

    Cox, Stephen K.

    1996-01-01

    The goal of this research has been to identify and describe the properties of climatically important cloud systems critically important to understanding their effects upon satellite remote sensing and the global climate. These goals have been pursued along several different but complementary lines of investigation: the design, construction, testing and application of instrumentation; the collection of data sets during Intensive Field Observation periods; the reduction and analysis of data collected during IFO's; and completion of research projects specifically designed to address important and timely research objectives. In the first year covered by this research proposal, three papers were authored in the refereed literature which reported completed analyses of FIRE 1 IFO studies initiated under the previous NASA funding of this topic area. microphysical and radiative properties of marine stratocumulus cloud systems deduced from tethered balloon observations were reported from the San Nicolas Island site of the first FIRE marine stratocumulus experiment. Likewise, in situ observations of radiation and dynamic properties of a cirrus cloud layer were reported from first FIRE cirrus IFO based from Madison, Wisconsin. In addition, application techniques were under development for monitoring cirrus cloud systems using a 403 MHz Doppler wind profiler system adapted with a RASS (Radio Acoustic Sounding System) and an infrared interferometer system; these instrument systems were used in subsequent deployments for the FIRE 2 Parsons, Kansas and FIRE 2 Porto Santo, ASTEX expeditions. In November 1991 and in June 1992, these two systems along with a complete complement of surface radiation and meteorology measurements were deployed to the two sites noted above as anchor points for the respective IFO'S. Subsequent research activity concentrated on the interpretation and integration of the IFO analyses in the context of the radiative properties of cloud systems and our ability

  3. Dynamic Turbulence Modelling in Large-eddy Simulations of the Cloud-topped Atmospheric Boundary Layer

    NASA Technical Reports Server (NTRS)

    Kirkpatrick, M. P.; Mansour, N. N.; Ackerman, A. S.; Stevens, D. E.

    2003-01-01

    The use of large eddy simulation, or LES, to study the atmospheric boundary layer dates back to the early 1970s when Deardor (1972) used a three-dimensional simulation to determine velocity and temperature scales in the convective boundary layer. In 1974 he applied LES to the problem of mixing layer entrainment (Deardor 1974) and in 1980 to the cloud-topped boundary layer (Deardor 1980b). Since that time the LES approach has been applied to atmospheric boundary layer problems by numerous authors. While LES has been shown to be relatively robust for simple cases such as a clear, convective boundary layer (Mason 1989), simulation of the cloud-topped boundary layer has proved more of a challenge. The combination of small length scales and anisotropic turbulence coupled with cloud microphysics and radiation effects places a heavy burden on the turbulence model, especially in the cloud-top region. Consequently, over the past few decades considerable effort has been devoted to developing turbulence models that are better able to parameterize these processes. Much of this work has involved taking parameterizations developed for neutral boundary layers and deriving corrections to account for buoyancy effects associated with the background stratification and local buoyancy sources due to radiative and latent heat transfer within the cloud (see Lilly 1962; Deardor 1980a; Mason 1989; MacVean & Mason 1990, for example). In this paper we hope to contribute to this effort by presenting a number of turbulence models in which the model coefficients are calculated dynamically during the simulation rather than being prescribed a priori.

  4. 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.

  5. Intercomparison of cloud model simulations of Arctic mixed-phase boundary layer clouds observed during SHEBA/FIRE-ACE

    SciTech Connect

    Morrison, H.; Zuidema, Paquita; Ackerman, Andrew

    2011-06-16

    An intercomparison of six cloud-resolving and large-eddy simulation models is presented. This case study is based on observations of a persistent mixed-phase boundary layer cloud gathered on 7 May, 1998 from the Surface Heat Budget of Arctic Ocean (SHEBA) and First ISCCP Regional Experiment - Arctic Cloud Experiment (FIRE-ACE). Ice nucleation is constrained in the simulations in a way that holds the ice crystal concentration approximately fixed, with two sets of sensitivity runs in addition to the baseline simulations utilizing different specified ice nucleus (IN) concentrations. All of the baseline and sensitivity simulations group into two distinct quasi-steady states associatedmore » with either persistent mixed-phase clouds or all-ice clouds after the first few hours of integration, implying the existence of multiple equilibria. These two states are associated with distinctly different microphysical, thermodynamic, and radiative characteristics. Most but not all of the models produce a persistent mixed-phase cloud qualitatively similar to observations using the baseline IN/crystal concentration, while small increases in the IN/crystal concentration generally lead to rapid glaciation and conversion to the all-ice state. Budget analysis indicates that larger ice deposition rates associated with increased IN/crystal concentrations have a limited direct impact on dissipation of liquid in these simulations. However, the impact of increased ice deposition is greatly enhanced by several interaction pathways that lead to an increased surface precipitation flux, weaker cloud top radiative cooling and cloud dynamics, and reduced vertical mixing, promoting rapid glaciation of the mixed-phase cloud for deposition rates in the cloud layer greater than about 1-2x10-5 g kg-1 s-1. These results indicate the critical importance of precipitation-radiative-dynamical interactions in simulating cloud phase, which have been neglected in previous fixed-dynamical parcel studies of

  6. Coupled Sulfur and Chlorine Chemistry in Venus' Upper Cloud Layer

    NASA Astrophysics Data System (ADS)

    Mills, Franklin P.

    2006-09-01

    Venus' atmosphere likely contains a rich variety of sulfur and chlorine compounds because HCl, SO2, and OCS have all been observed. Photodissociation of CO2 and SO2 in the upper cloud layer produces oxygen which can react directly or indirectly with SO2 to form SO3 and eventually H2SO4. Photodissociation of HCl within and above the upper cloud layer produces chlorine which can react with CO and O2 to form ClCO and ClC(O)OO. These two species have been identified as potentially critical intermediaries in the production of CO2. Much less work has been done on the potential coupling between sulfur and chlorine chemistry that may occur within the upper cloud layer. Several aspects have been examined in recent modeling: (1) linkage of the CO2 and sulfur oxidation cycles (based on ideas from Yung and DeMore, 1982), (2) reaction of Cl with SO2 to form ClSO2 (based on ideas from DeMore et al., 1985), and (3) the chemistry of SmCln for m,n = 1,2 (based on preliminary work in Mills, 1998). Initial results suggest the chemistry of SmCln may provide a pathway for accelerated production of polysulfur, Sx, if the oxygen abundance in the upper cloud layer is as small as is implied by the observational limit on O2 (Trauger and Lunine, 1983). Initial results also suggest that ClSO2 can act as a buffer which helps increase the scale height of SO2 and decrease the rate of production of H2SO4. This presentation will describe the results from this modeling; discuss their potential implications for the CO2, sulfur oxidation, and polysulfur cycles; and outline key observations from Venus Express that can help resolve existing questions concerning the chemistry of Venus' upper cloud. Partial funding for this research was provided by the Australian Research Council.

  7. Height Distribution Between Cloud and Aerosol Layers from the GLAS Spaceborne Lidar in the Indian Ocean Region

    NASA Technical Reports Server (NTRS)

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

    2005-01-01

    The Geoscience Laser Altimeter System (GLAS), a nadir pointing lidar on the Ice Cloud and land Elevation Satellite (ICESat) launched in 2003, now provides important new global measurements of the relationship between the height distribution of cloud and aerosol layers. GLAS data have the capability to detect, locate, and distinguish between cloud and aerosol layers in the atmosphere up to 40 km altitude. The data product algorithm tests the product of the maximum attenuated backscatter coefficient b'(r) and the vertical gradient of b'(r) within a layer against a predetermined threshold. An initial case result for the critical Indian Ocean region is presented. From the results the relative height distribution between collocated aerosol and cloud shows extensive regions where cloud formation is well within dense aerosol scattering layers at the surface. Citation: Hart, W. D., J. D. Spinhime, S. P. Palm, and D. L. Hlavka (2005), Height distribution between cloud and aerosol layers from the GLAS spaceborne lidar in the Indian Ocean region,

  8. Stratospheric effects on trends of mesospheric ice clouds (Invited)

    NASA Astrophysics Data System (ADS)

    Luebken, F.; Baumgarten, G.; Berger, U.

    2009-12-01

    Ice layers in the summer mesosphere at middle and polar latitudes appear as `noctilucent clouds' (NLC) and `polar mesosphere clouds'(PMC) when observed by optical methods from the ground or from satellites, respectively. A newly developed model of the atmosphere called LIMA (Leibniz Institute Middle Atmosphere Model) nicely reproduces the mean conditions of the summer mesopause region and is used to study the ice layer morphology (LIMA/ice). LIMA nudges to ECMWF data in the troposphere and lower stratosphere which influences the background conditions in the mesosphere and ice cloud morphology. Since ice layer formation is very sensitive to the thermal structure of the mesopause region the morphology of NLC and PMC is frequently discussed in terms of long term variations. Model runs of LIMA/ice are now available for 1961 until 2008. A strong correlation between temperatures and PMC altitudes is observed. Applied to historical measurements this gives negligible temperature trends at PMC altitudes (approximately 0.01-0.02 K/y). Trace gas concentrations are kept constant in LIMA except for water vapor which is modified by variable solar radiation. Still, long term trends in temperatures and ice layer parameters are observed, consistent with observations. We present results regarding inter-annual variability of upper mesosphere temperatures, water vapor, and ice clouds, and also long term variations. We compare our model results with satellite borne and lidar observations including some record high NLC parameters measured in the summer season of 2009. The latitudinal dependence of trends and ice layer parameters is discussed, including a NH/SH comparison. We will present an explanation of the trends in the background atmosphere and ice layer parameters.

  9. Intercomparisons of Marine Boundary Layer Cloud Properties from the ARM CAP-MBL Campaign and Two MODIS Cloud Products

    NASA Technical Reports Server (NTRS)

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

    2017-01-01

    From April 2009 to December 2010, the Department of Energy (DOE) 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 inter-comparison 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 (AMF) and two Moderate Resolution Spectroradiometer (MODIS) cloud products (GSFC-MODIS and CERES-MODIS). A total of 63 daytime single-layer MBL cloud cases are selected for inter-comparison. Comparison of collocated retrievals indicates that the two MODIS cloud products agree well on both COT and CER retrievals, with the correlation coefficient R greater than 0.95 despite their significant difference in spatial sampling. In both MODIS products, the CER retrievals based on the 2.1 micrometers band (CER(sub 2.1)) is significantly smaller than that based on the 3.7 micrometers band (CER(sub 3.7)). 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 CER(sub 3.7) and CER(sub 2.1) retrievals have a lower correlation (R is approximately 0.5) with the ground-based retrievals. For the 63 selected cases, they are on average larger than ground observations by about 1.5 micrometers and 3.0 micrometers, respectively. Taking into account that the MODIS CER retrievals are only sensitive to cloud top reduces the bias only by 0.5 micrometers.

  10. A Climatology of Midlatitude Continental Clouds from the ARM SGP Site. Part II; Cloud Fraction and Surface Radiative Forcing

    NASA Technical Reports Server (NTRS)

    Xi, B.; Minnis, P.

    2006-01-01

    Data collected at the Department of Energy Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) Central Facility (SCF) are analyzed to determine the monthly and hourly variations of cloud fraction and radiative forcing between January 1997 and December 2002. Cloud fractions are estimated for total cloud cover and for single-layered low (0-3 km), middle (3-6 km), and high clouds (more than 6 km) using ARM SCG ground-based paired lidar-radar measurements. Shortwave (SW) and longwave (LW) fluxes are derived from up- and down-looking standard precision spectral pyranometers and precision infrared radiometer measurements with uncertainties of approximately 10 Wm(exp -2). The annual averages of total, and single-layered low, middle and high cloud fractions are 0.49, 0.11, 0.03, and 0.17, respectively. Both total and low cloud amounts peak during January and February and reach a minimum during July and August, high clouds occur more frequently than other types of clouds with a peak in summer. The average annual downwelling surface SW fluxes for total and low clouds (151 and 138 Wm(exp-2), respectively) are less than those under middle and high clouds (188 and 201 Wm(exp -2), respectively), but the downwelling LW fluxes (349 and 356 Wm(exp -2)) underneath total and low clouds are greater than those from middle and high clouds (337 and 333 Wm(exp -2)). Low clouds produce the largest LW warming (55 Wm(exp -2) and SW cooling (-91 Wm(exp -2)) effects with maximum and minimum absolute values in spring and summer, respectively. High clouds have the smallest LW warming (17 Wm(exp -2)) and SW cooling (-37 Wm(exp -2)) effects at the surface. All-sky SW CRF decreases and LW CRF increases with increasing cloud fraction with mean slopes of -0.984 and 0.616 Wm(exp -2)%(exp -1), respectively. Over the entire diurnal cycle, clouds deplete the amount of surface insolation more than they add to the downwelling LW flux. The calculated CRFs do not appear to be significantly

  11. The evolution of nocturnal boundary-layer clouds in southern West Africa - a case study from DACCIWA

    NASA Astrophysics Data System (ADS)

    Adler, Bianca; Kalthoff, Norbert; Babić, Karmen; Lohou, Fabienne; Dione, Cheikh; Lothon, Marie; Pedruzo-Bagazgoitia, Xabier

    2017-04-01

    During the monsoon season, the atmospheric boundary layer in southern West Africa is characterised by various kinds of low-level clouds which experience a distinct diurnal cycle. During the night, extensive low-level stratiform clouds frequently form with a cloud base often less than few hundred metres above ground. After sunrise the cloud base slowly starts rising and eventually a transition to convective clouds occurs. While the existence of the clouds is documented in satellite images and synoptic observations, little is known about the mechanisms controlling their evolution. To provide observational evidence, a field campaign was conducted in southern West Africa in June and July 2016 within the framework of the Dynamics-aerosol-chemistry-cloud interactions in West Africa (DACCIWA) project. Comprehensive ground-based in situ and remote sensing measurements were performed at three different supersites in Ghana, Benin and Nigeria. In this contribution, we present the diurnal cycle of boundary-layer clouds for a typical day using data from a supersite at Savè in Benin. Due to the synergy of various instruments, we are able to obtain detailed information on the evolution of the clouds as well as on the boundary-layer structure with high temporal and vertical resolution. By combining ceilometer, cloud radar and microwave radiometer data we determined the cloud base, -depth and -density. The clouds form in the same layer as a nocturnal low-level jet (NLLJ), which we probe by sodar and UHF profiler. There is evidence for a strong link between the height and strength of the NLLJ and the density of the nocturnal clouds.

  12. Winds in the Middle Cloud Deck From the Near-IR Imaging by the Venus Monitoring Camera Onboard Venus Express

    NASA Astrophysics Data System (ADS)

    Khatuntsev, I. V.; Patsaeva, M. V.; Titov, D. V.; Ignatiev, N. I.; Turin, A. V.; Fedorova, A. A.; Markiewicz, W. J.

    2017-11-01

    For more than 8 years the Venus Monitoring Camera (VMC) onboard the Venus Express orbiter performed continuous imaging of the Venus cloud layer in UV, visible and near-IR filters. We applied the correlation approach to sequences of the near-IR images at 965 nm to track cloud features and determine the wind field in the middle and lower cloud (49-57 km). From the VMC images that spanned from December of 2006 through August of 2013 we derived zonal and meridional components of the wind field. In low-to-middle latitudes (5-65°S) the velocity of the retrograde zonal wind was found to be 68-70 m/s. The meridional wind velocity slowly decreases from peak value of +5.8 ± 1.2 m/s at 15°S to 0 at 65-70°S. The mean meridional speed has a positive sign at 5-65°S suggesting equatorward flow. This result, together with the earlier measurements of the poleward flow at the cloud tops, indicates the presence of a closed Hadley cell in the altitude range 55-65 km. Long-term variations of zonal and meridional velocity components were found during 1,200 Earth days of observation. At 20° ± 5°S the zonal wind speed increases from -67.18 ± 1.81 m/s to -77.30 ± 2.49 m/s. The meridional wind gradually increases from +1.30 ± 1.82 m/s to +8.53 ± 2.14 m/s. Following Bertaux et al. (2016) we attribute this long-term trend to the influence from the surface topography on the dynamical process in the atmosphere via the upward propagation of gravity waves that became apparent in the VMC observations due to slow drift of the Venus Express orbit over Aphrodite Terra.

  13. Single-Column Model Simulations of Subtropical Marine Boundary-Layer Cloud Transitions Under Weakening Inversions

    NASA Astrophysics Data System (ADS)

    Neggers, R. A. J.; Ackerman, A. S.; Angevine, W. M.; Bazile, E.; Beau, I.; Blossey, P. N.; Boutle, I. A.; de Bruijn, C.; Cheng, A.; van der Dussen, J.; Fletcher, J.; Dal Gesso, S.; Jam, A.; Kawai, H.; Cheedela, S. K.; Larson, V. E.; Lefebvre, M.-P.; Lock, A. P.; Meyer, N. R.; de Roode, S. R.; de Rooy, W.; Sandu, I.; Xiao, H.; Xu, K.-M.

    2017-10-01

    Results are presented of the GASS/EUCLIPSE single-column model intercomparison study on the subtropical marine low-level cloud transition. A central goal is to establish the performance of state-of-the-art boundary-layer schemes for weather and climate models for this cloud regime, using large-eddy simulations of the same scenes as a reference. A novelty is that the comparison covers four different cases instead of one, in order to broaden the covered parameter space. Three cases are situated in the North-Eastern Pacific, while one reflects conditions in the North-Eastern Atlantic. A set of variables is considered that reflects key aspects of the transition process, making use of simple metrics to establish the model performance. Using this method, some longstanding problems in low-level cloud representation are identified. Considerable spread exists among models concerning the cloud amount, its vertical structure, and the associated impact on radiative transfer. The sign and amplitude of these biases differ somewhat per case, depending on how far the transition has progressed. After cloud breakup the ensemble median exhibits the well-known "too few too bright" problem. The boundary-layer deepening rate and its state of decoupling are both underestimated, while the representation of the thin capping cloud layer appears complicated by a lack of vertical resolution. Encouragingly, some models are successful in representing the full set of variables, in particular, the vertical structure and diurnal cycle of the cloud layer in transition. An intriguing result is that the median of the model ensemble performs best, inspiring a new approach in subgrid parameterization.

  14. Integration of hybrid wireless networks in cloud services oriented enterprise information systems

    NASA Astrophysics Data System (ADS)

    Li, Shancang; Xu, Lida; Wang, Xinheng; Wang, Jue

    2012-05-01

    This article presents a hybrid wireless network integration scheme in cloud services-based enterprise information systems (EISs). With the emerging hybrid wireless networks and cloud computing technologies, it is necessary to develop a scheme that can seamlessly integrate these new technologies into existing EISs. By combining the hybrid wireless networks and computing in EIS, a new framework is proposed, which includes frontend layer, middle layer and backend layers connected to IP EISs. Based on a collaborative architecture, cloud services management framework and process diagram are presented. As a key feature, the proposed approach integrates access control functionalities within the hybrid framework that provide users with filtered views on available cloud services based on cloud service access requirements and user security credentials. In future work, we will implement the proposed framework over SwanMesh platform by integrating the UPnP standard into an enterprise information system.

  15. Surface Layer Flux Processes During Cloud Intermittency and Advection above a Middle Rio Grande Riparian Forest, New Mexico

    NASA Astrophysics Data System (ADS)

    Cleverly, J. R.; Prueger, J.; Cooper, D. I.; Hipps, L.; Eichinger, W.

    2002-12-01

    An intensive field campaign was undertaken to bring together state-of-the-art methodologies for investigating surface layer physical characteristics over a desert riparian forest. Three-dimensional sonic eddy covariance (3SEC), LIDAR, SODAR, Radiosonde, one-dimensional propeller eddy covariance (1PEC), heat dissipation sap flux, and leaf gas exchange were simultaneously in use 13 -- 21 June 1999 at Bosque del Apache National Wildlife Refuge (NWR) in New Mexico. A one hour period of intense advection was identified by /line{v} >> 0 and /line{u} = 0, indicating that wind direction was transverse to the riparian corridor. The period of highest /line{v} was 1400 h on 20 June; this hour experienced intermittent cloud cover and enhanced mesoscale forcing of surface fluxes. High-frequency (20 Hz) time series of u, v, w, q, θ , and T were collected for spectral, cospectral, and wavelet analyses. These time series analyses illustrate scales at which processes co-occur. At high frequencies (> 0.015 Hz), /line{T' q'} > 0, and (KH)/ (KW) = 1. At low frequencies, however, /line{T' q'} < 0, and (KH)/(KW) !=q 1. Under these transient conditions, frequencies below 0.015 Hz are associated with advection. While power cospectra are useful in associating processes at certain frequencies, further analysis must be performed to determine whether such examples of aphasia are localized to transient events or constant through time. Continuous wavelet transformation (CWT) sacrifices localization in frequency space for localization in time. Mother wavelets were evaluated, and Daubechies order 10 wavelet was found to reduce red noise and leakage near the spectral gap. The spectral gap is a frequency domain between synoptic and turbulent scales. Low frequency turbulent structures near the spectral gap in the time series of /line{T' q'}, /line{w' T'}, and /line{w' q'} followed a perturbation--relaxation pattern to cloud cover. Further cloud cover in the same hour did not produce the low

  16. Shallow marine cloud topped boundary layer in atmospheric models

    NASA Astrophysics Data System (ADS)

    Janjic, Zavisa

    2017-04-01

    A common problem in many atmospheric models is excessive expansion over cold water of shallow marine planetary boundary layer (PBL) topped by a thin cloud layer. This phenomenon is often accompanied by spurious light precipitation. The "Cloud Top Entrainment Instability" (CTEI) was proposed as an explanation of the mechanism controlling this process in reality thereby preventing spurious enlargement of the cloudy area and widely spread light precipitation observed in the models. A key element of this hypothesis is evaporative cooling at the PBL top. However, the CTEI hypothesis remains controversial. For example, a recent direct simulation experiment indicated that the evaporative cooling couldn't explain the break-up of the cloudiness as hypothesized by the CTEI. Here, it is shown that the cloud break-up can be achieved in numerical models by a further modification of the nonsingular implementation of the Mellor-Yamada Level 2.5 turbulence closure model (MYJ) developed at the National Centers for Environmental Prediction (NCEP) Washington. Namely, the impact of moist convective instability is included into the turbulent energy production/dissipation equation if (a) the stratification is stable, (b) the lifting condensation level (LCL) for a particle starting at a model level is below the next upper model level, and (c) there is enough turbulent kinetic energy so that, due to random vertical turbulent motions, a particle starting from a model level can reach its LCL. The criterion (c) should be sufficiently restrictive because otherwise the cloud cover can be completely removed. A real data example will be shown demonstrating the ability of the method to break the spurious cloud cover during the day, but also to allow its recovery over night.

  17. Cloud and boundary layer structure over San Nicolas Island during FIRE

    NASA Technical Reports Server (NTRS)

    Albrecht, Bruce A.; Fairall, Christopher W.; Syrett, William J.; Schubert, Wayne H.; Snider, Jack B.

    1990-01-01

    The temporal evolution of the structure of the marine boundary layer and of the associated low-level clouds observed in the vicinity of the San Nicolas Island (SNI) is defined from data collected during the First ISCCP Regional Experiment (FIRE) Marine Stratocumulus Intense Field Observations (IFO) (July 1 to 19). Surface, radiosonde, and remote-sensing measurements are used for this analysis. Sounding from the Island and from the ship Point Sur, which was located approximately 100 km northwest of SNI, are used to define variations in the thermodynamic structure of the lower-troposphere on time scales of 12 hours and longer. Time-height sections of potential temperature and equivalent potential temperature clearly define large-scale variations in the height and the strength of the inversion and periods where the conditions for cloud-top entrainment instability (CTEI) are met. Well defined variations in the height and the strength of the inversion were associated with a Cataline Eddy that was present at various times during the experiment and with the passage of the remnants of a tropical cyclone on July 18. The large-scale variations in the mean thermodynamic structure at SNI correlate well with those observed from the Point Sur. Cloud characteristics are defined for 19 days of the experiment using data from a microwave radiometer, a cloud ceilometer, a sodar, and longwave and shortwave radiometers. The depth of the cloud layer is estimated by defining inversion heights from the sodar reflectivity and cloud-base heights from a laser ceilometer. The integrated liquid water obtained from NOAA's microwave radiometer is compared with the adiabatic liquid water content that is calculated by lifting a parcel adiabatically from cloud base. In addition, the cloud structure is characterized by the variability in cloud-base height and in the integrated liquid water.

  18. Assessing the accuracy of MISR and MISR-simulated cloud top heights using CloudSat- and CALIPSO-retrieved hydrometeor profiles

    NASA Astrophysics Data System (ADS)

    Hillman, Benjamin R.; Marchand, Roger T.; Ackerman, Thomas P.; Mace, Gerald G.; Benson, Sally

    2017-03-01

    Satellite retrievals of cloud properties are often used in the evaluation of global climate models, and in recent years satellite instrument simulators have been used to account for known retrieval biases in order to make more consistent comparisons between models and retrievals. Many of these simulators have seen little critical evaluation. Here we evaluate the Multiangle Imaging Spectroradiometer (MISR) simulator by using visible extinction profiles retrieved from a combination of CloudSat, CALIPSO, MODIS, and AMSR-E observations as inputs to the MISR simulator and comparing cloud top height statistics from the MISR simulator with those retrieved by MISR. Overall, we find that the occurrence of middle- and high-altitude topped clouds agrees well between MISR retrievals and the MISR-simulated output, with distributions of middle- and high-topped cloud cover typically agreeing to better than 5% in both zonal and regional averages. However, there are significant differences in the occurrence of low-topped clouds between MISR retrievals and MISR-simulated output that are due to differences in the detection of low-level clouds between MISR and the combined retrievals used to drive the MISR simulator, rather than due to errors in the MISR simulator cloud top height adjustment. This difference highlights the importance of sensor resolution and boundary layer cloud spatial structure in determining low-altitude cloud cover. The MISR-simulated and MISR-retrieved cloud optical depth also show systematic differences, which are also likely due in part to cloud spatial structure.

  19. Characterizing the Influence of the General Circulation on Marine Boundary Layer Clouds

    NASA Technical Reports Server (NTRS)

    Rozendaal, Margaret A.; Rossow, William B.; Hansen, James E. (Technical Monitor)

    2001-01-01

    The seasonal and intraseasonal variability of boundary layer cloud in the subtropical eastern oceans are studied using combined data from the International Satellite Cloud Climatology Project (ISCCP) and the European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis. Spectral analysis reveals that most of the time variability of cloud properties occurs on seasonal to annual time scales. The variance decreases one to two orders of magnitude for each decade of time scale decrease, indicating that daily to monthly time scales have smaller, but non-negligible variability. The length of these dominant time scales suggests that the majority of the variability is influenced by the general circulation and its interaction with boundary layer turbulence, rather than a product of boundary layer turbulence alone. Previous datasets have lacked the necessary resolution in either time or in space to properly characterize variability on synoptic scales; this is remedied by using global satellite-retrieved cloud properties. We characterize the intraseasonal subtropical cloud variability in both hemispheres and in different seasons. In addition to cloud fraction, we examine variability of cloud optical thickness - cloud top pressure frequency distributions. Despite the large concentration of research on the variability of Northern Hemisphere (NH) regions during summer, it is noted that the largest amplitude intraseasonal variability in the NH regions occurs during local winter. The effect of intraseasonal variability on the calculation and interpretation of seasonal results is investigated. Decreases in seasonally averaged cloud cover, optical thickness and cloud top pressure from the May-through-September season to the November-through-March season are most apparent in the NH regions. Further analysis indicates that these changes are due to an increase in frequency, but a decrease in the persistence of synoptic events. In addition, changes in cloud top pressure and

  20. Solar cycle and long term variations of mesospheric ice layers

    NASA Astrophysics Data System (ADS)

    Lübken, Franz-Josef; Berger, Uwe; Kiliani, Johannes; Baumgarten, Gerd; Fiedler, Jens; Gerding, Michael

    2010-05-01

    Ice layers in the summer mesosphere at middle and polar latitudes, frequently called `noctilucent clouds' (NLC) or `polar mesosphere clouds'(PMC), are considered to be sensitive indicators of long term changes in the middle atmosphere. We present a summary of long term observations from the ground and from satellites and compare with results from the LIMA model (Leibniz Institute Middle Atmosphere Model). LIMA nicely reproduces mean conditions of the summer mesopause region and also mean characteristics of ice layers. LIMA nudges to ECMWF data in the troposphere and lower stratosphere which influences the background conditions in the mesosphere and thereby the morphology of ice clouds. A strong correlation between temperatures and PMC altitudes is observed. Applied to historical measurements this give s negligible temperature trends at PMC altitudes (approximately 0.01-0.02 K/y). Trace gas concentrations are kept constant in LIMA except for water vapor which is modified by variable solar radiation. Still, long term trends in temperatures and ice layer parameters are observed, consistent with observations. As will be shown, these trends originate in the stratosphere. Solar cycle effects are expected in ice layers due to variations in background temperatures and water paper. We will present results from LIMA regarding solar cycle variations and compare with NLC observations at our lidar stations in Kühlungsborn (54°N) and ALOMAR (69°N), and also with satellite measurements.

  1. Dust in brown dwarfs. III. Formation and structure of quasi-static cloud layers

    NASA Astrophysics Data System (ADS)

    Woitke, P.; Helling, Ch.

    2004-01-01

    In this paper, first solutions of the dust moment equations developed in (Woitke & Helling \\cite{wh2003a}) for the description of dust formation and precipitation in brown dwarf and giant gas planet atmospheres are presented. We consider the special case of a static brown dwarf atmosphere, where dust particles continuously nucleate from the gas phase, grow by the accretion of molecules, settle gravitationally and re-evaporate thermally. Mixing by convective overshoot is assumed to replenish the atmosphere with condensable elements, which is necessary to counterbalance the loss of condensable elements by dust formation and gravitational settling (no dust without mixing). Applying a kinetic description of the relevant microphysical and chemical processes for TiO2-grains, the model makes predictions about the large-scale stratification of dust in the atmosphere, the depletion of molecules from the gas phase, the supersaturation of the gas in the atmosphere as well as the mean size and the mass fraction of dust grains as function of depth. Our results suggest that the presence of relevant amounts of dust is restricted to a layer, where the upper boundary (cloud deck) is related to the requirement of a minimum mixing activity (mixing time-scale τmix ≈ 10 6 s) and the lower boundary (cloud base) is determined by the thermodynamical stability of the grains. The nucleation occurs around the cloud deck where the gas is cool, strongly depleted, but nevertheless highly supersaturated (S ≫ 1). These particles settle gravitationally and populate the warmer layers below, where the in situ formation (nucleation) is ineffective or even not possible. During their descent, the particles grow and reach mean radii of ≈30 \\mum ... 400 \\mum at the cloud base, but the majority of the particles in the cloud layer remains much smaller. Finally, the dust grains sink into layers which are sufficiently hot to cause their thermal evaporation. Hence, an effective transport mechanism

  2. Ice Cloud Formation and Dehydration in the Tropical Tropopause Layer

    NASA Technical Reports Server (NTRS)

    Jensen, Eric; Gore, Warren J. (Technical Monitor)

    2002-01-01

    Stratospheric water vapor is important not only for its greenhouse forcing, but also because it plays a significant role in stratospheric chemistry. Several recent studies have focused on the potential for dehydration due to ice cloud formation in air rising slowly through the tropical tropopause layer (TTL). Holton and Gettelman showed that temperature variations associated with horizontal transport of air in the TTL can drive ice cloud formation and dehydration, and Gettelman et al. recently examined the cloud formation and dehydration along kinematic trajectories using simple assumptions about the cloud properties. In this study, a Lagrangian, one-dimensional cloud model has been used to further investigate cloud formation and dehydration as air is transported horizontally and vertically through the TTL. Time-height curtains of temperature are extracted from meteorological analyses. The model tracks the growth, advection, and sedimentation of individual cloud particles. The regional distribution of clouds simulated in the model is comparable to the subvisible cirrus distribution indicated by SAGE II. The simulated cloud properties and cloud frequencies depend strongly on the assumed supersaturation threshold for ice nucleation. The clouds typically do not dehydrate the air along trajectories down to the temperature minimum saturation mixing ratio. Rather the water vapor mixing ratio crossing the tropopause along trajectories is 10-50% larger than the saturation mixing ratio. I will also discuss the impacts of Kelvin waves and gravity waves on cloud properties and dehydration efficiency. These simulations can be used to determine whether observed lower stratospheric water vapor mixing ratios can be explained by dehydration associated with in situ TTL cloud formation alone.

  3. The Sensitivity of Numerical Simulations of Cloud-Topped Boundary Layers to Cross-Grid Flow

    NASA Astrophysics Data System (ADS)

    Wyant, Matthew C.; Bretherton, Christopher S.; Blossey, Peter N.

    2018-02-01

    In mesoscale and global atmospheric simulations with large horizontal domains, strong horizontal flow across the grid is often unavoidable, but its effects on cloud-topped boundary layers have received comparatively little study. Here the effects of cross-grid flow on large-eddy simulations of stratocumulus and trade-cumulus marine boundary layers are studied across a range of grid resolutions (horizontal × vertical) between 500 m × 20 m and 35 m × 5 m. Three cases are simulated: DYCOMS nocturnal stratocumulus, BOMEX trade cumulus, and a GCSS stratocumulus-to-trade cumulus case. Simulations are performed with a stationary grid (with 4-8 m s-1 horizontal winds blowing through the cyclic domain) and a moving grid (equivalent to subtracting off a fixed vertically uniform horizontal wind) approximately matching the mean boundary-layer wind speed. For stratocumulus clouds, cross-grid flow produces two primary effects on stratocumulus clouds: a filtering of fine-scale resolved turbulent eddies, which reduces stratocumulus cloud-top entrainment, and a vertical broadening of the stratocumulus-top inversion which enhances cloud-top entrainment. With a coarse (20 m) vertical grid, the former effect dominates and leads to strong increases in cloud cover and LWP, especially as horizontal resolution is coarsened. With a finer (5 m) vertical grid, the latter effect is stronger and leads to small reductions in cloud cover and LWP. For the BOMEX trade cumulus case, cross-grid flow tends to produce fewer and larger clouds with higher LWP, especially for coarser vertical grid spacing. The results presented are robust to choice of scalar advection scheme and Courant number.

  4. Response of mixed-phase boundary layer clouds with rapid and slow ice nucleation processes to cloud-top temperature trend

    NASA Astrophysics Data System (ADS)

    Fridlind, A. M.; Avramov, A.; Ackerman, A. S.; Alpert, P. A.; Knopf, D. A.; DeMott, P. J.; Brooks, S. D.; Glen, A.

    2015-12-01

    It has been argued on the basis of some laboratory data sets, observed mixed-phase cloud systems, and numerical modeling studies that weakly active or slowly consumed ice forming nuclei (IFN) may be important to natural cloud systems. It has also been argued on the basis of field measurements that ice nucleation under mixed-phase conditions appears to occur predominantly via a liquid-phase mechanism, requiring the presence of liquid droplets prior to substantial ice nucleation. Here we analyze the response of quasi-Lagrangian large-eddy simulations of mixed-phase cloud layers to IFN operating via a liquid-phase mode using assumptions that result in either slow or rapid depletion of IFN from the cloudy boundary layer. Using several generalized case studies that do not exhibit riming or drizzle, based loosely on field campaign data, we vary environmental conditions such that the cloud-top temperature trend varies. One objective of this work is to identify differing patterns in ice formation intensity that may be distinguishable from ground-based or satellite platforms.

  5. Equatorial cloud level convection on Venus

    NASA Astrophysics Data System (ADS)

    Lee, Yeon Joo; Imamura, Takeshi; Sugiyama, Koichiro; Sato, Takao M.; Maejima, Yasumitsu

    2016-10-01

    In the equatorial region on Venus, a clear cloud top morphology difference depending on solar local time has been observed through UV images. Laminar flow shaped clouds are shown on the morning side, and convective-like cells on the afternoon side (Titov et al. 2012). Baker et al. (1998) suggested that deep convective motions in the low-to-middle cloud layers at the 40-60 km range can explain cellular shapes. Imamura et al. (2014), however argued that this cannot be a reason, as convection in the low-to-middle cloud layers can be suppressed near sub solar regions due to a stabilizing effect by strong solar heating. We suggest that the observed feature may be related to strong solar heating at local noon time (Lee et al. 2015). Horizontal uneven distribution of an unknown UV absorber and/or cloud top structure may trigger horizontal convection (Toigo et al. 1994). In order to examine these possibilities, we processed 1-D radiative transfer model calculations from surface to 100 km altitude (SHDOM, Evans 1998), which includes clouds at 48-71 km altitudes (Crisp et al. 1986). The results on the equatorial thermal cooling and solar heating profiles were employed in a 2D fluid dynamic model calculation (CReSS, Tsuboki and Sakakibara 2007). The calculation covered an altitude range of 40-80 km and a 100-km horizontal distance. We compared three conditions; an 'effective' global circulation condition that cancels out unbalanced net radiative energy at equator, a condition without such global circulation effect, and the last condition assumed horizontally inhomogeneous unknown UV absorber distribution. Our results show that the local time dependence of lower level cloud convection is consistent with Imamura et al.'s result, and suggest a possible cloud top level convection caused by locally unbalanced net energy and/or horizontally uneven solar heating. This may be related to the observed cloud morphology in UV images. The effective global circulation condition, however

  6. Testing the Two-Layer Model for Correcting Clear Sky Reflectance near Clouds

    NASA Technical Reports Server (NTRS)

    Wen, Guoyong; Marshak, Alexander; Evans, Frank; Varnai, Tamas; Levy, Rob

    2015-01-01

    A two-layer model (2LM) was developed in our earlier studies to estimate the clear sky reflectance enhancement due to cloud-molecular radiative interaction at MODIS at 0.47 micrometers. Recently, we extended the model to include cloud-surface and cloud-aerosol radiative interactions. We use the LES/SHDOM simulated 3D true radiation fields to test the 2LM for reflectance enhancement at 0.47 micrometers. We find: The simple model captures the viewing angle dependence of the reflectance enhancement near cloud, suggesting the physics of this model is correct; the cloud-molecular interaction alone accounts for 70 percent of the enhancement; the cloud-surface interaction accounts for 16 percent of the enhancement; the cloud-aerosol interaction accounts for an additional 13 percent of the enhancement. We conclude that the 2LM is simple to apply and unbiased.

  7. Constraining the low-cloud optical depth feedback at middle and high latitudes using satellite observations

    DOE PAGES

    Terai, C. R.; Klein, S. A.; Zelinka, M. D.

    2016-08-26

    The increase in cloud optical depth with warming at middle and high latitudes is a robust cloud feedback response found across all climate models. This study builds on results that suggest the optical depth response to temperature is timescale invariant for low-level clouds. The timescale invariance allows one to use satellite observations to constrain the models' optical depth feedbacks. Three passive-sensor satellite retrievals are compared against simulations from eight models from the Atmosphere Model Intercomparison Project (AMIP) of the 5th Coupled Model Intercomparison Project (CMIP5). This study confirms that the low-cloud optical depth response is timescale invariant in the AMIPmore » simulations, generally at latitudes higher than 40°. Compared to satellite estimates, most models overestimate the increase in optical depth with warming at the monthly and interannual timescales. Many models also do not capture the increase in optical depth with estimated inversion strength that is found in all three satellite observations and in previous studies. The discrepancy between models and satellites exists in both hemispheres and in most months of the year. A simple replacement of the models' optical depth sensitivities with the satellites' sensitivities reduces the negative shortwave cloud feedback by at least 50% in the 40°–70°S latitude band and by at least 65% in the 40°–70°N latitude band. Furthermore, based on this analysis of satellite observations, we conclude that the low-cloud optical depth feedback at middle and high latitudes is likely too negative in climate models.« less

  8. Constraining the low-cloud optical depth feedback at middle and high latitudes using satellite observations

    SciTech Connect

    Terai, C. R.; Klein, S. A.; Zelinka, M. D.

    The increase in cloud optical depth with warming at middle and high latitudes is a robust cloud feedback response found across all climate models. This study builds on results that suggest the optical depth response to temperature is timescale invariant for low-level clouds. The timescale invariance allows one to use satellite observations to constrain the models' optical depth feedbacks. Three passive-sensor satellite retrievals are compared against simulations from eight models from the Atmosphere Model Intercomparison Project (AMIP) of the 5th Coupled Model Intercomparison Project (CMIP5). This study confirms that the low-cloud optical depth response is timescale invariant in the AMIPmore » simulations, generally at latitudes higher than 40°. Compared to satellite estimates, most models overestimate the increase in optical depth with warming at the monthly and interannual timescales. Many models also do not capture the increase in optical depth with estimated inversion strength that is found in all three satellite observations and in previous studies. The discrepancy between models and satellites exists in both hemispheres and in most months of the year. A simple replacement of the models' optical depth sensitivities with the satellites' sensitivities reduces the negative shortwave cloud feedback by at least 50% in the 40°–70°S latitude band and by at least 65% in the 40°–70°N latitude band. Furthermore, based on this analysis of satellite observations, we conclude that the low-cloud optical depth feedback at middle and high latitudes is likely too negative in climate models.« less

  9. Analysis of Meteorological Data Obtained During Flight in a Supercooled Stratiform Cloud of High Liquid-Water Content

    NASA Technical Reports Server (NTRS)

    Perkins, Porter J.; Kline, Dwight B.

    1951-01-01

    Flight icing-rate data obtained in a dense and. abnormally deep supercooled stratiform cloud system indicated the existence of liquid-water contents generally exceeding values in amount and extent previously reported over the midwestern sections of the United States. Additional information obtained during descent through a part of the cloud system indicated liquid-water contents that significantly exceeded theoretical values, especially near the middle of the cloud layer.. The growth of cloud droplets to sizes that resulted in sedimentation from the upper portions of the cloud is considered to be a possible cause of the high water contents near the center of the cloud layer. Flight measurements of the vertical temperature distribution in the cloud layer indicated a rate of change of temperature with altitude exceeding that of the moist adiabatic lapse rate. This excessive rate of change is considered to have contributed to the severity of the condition.

  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 thinmore » 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.« less

  11. A Modeling Study of the Spatial Structure of Electric Fields Generated by Electrified Clouds with Screening Layers

    NASA Astrophysics Data System (ADS)

    Biagi, C. J.; Cummins, K. L.

    2015-12-01

    The growing possibility of inexpensive airborne observations of electric fields using one or more small UAVs increases the importance of understanding what can be determined about cloud electrification and associated electric fields outside cloud boundaries. If important information can be inferred from carefully selected flight paths outside of a cloud, then the aircraft and its instrumentation will be much cheaper to develop and much safer to operate. These facts have led us to revisit this long-standing topic using quasi-static, finite-element modeling inside and outside arbitrarily shaped clouds with a variety of internal charge distributions. In particular, we examine the effect of screening layers on electric fields outside of electrified clouds by comparing modeling results for charged clouds having electrical conductivities that are both equal to and lower than the surrounding clear air. The comparisons indicate that the spatial structure of the electric field is approximately the same regardless of the difference in the conductivities between the cloud and clear air and the formation of a screening layer, even for altitude-dependent electrical conductivities. This result is consistent with the numerical modeling results reported by Driscoll et al [1992]. The similarity of the spatial structure of the electric field outside of clouds with and without a screening layer suggests that "bulk" properties related to cloud electrification might be determined using measurements of the electric field at multiple locations in space outside the cloud, particularly at altitude. Finally, for this somewhat simplified model, the reduction in electric field magnitude outside the cloud due to the presence of a screening layer exhibits a simple dependence on the difference in conductivity between the cloud and clear air. These results are particularly relevant for studying clouds that are not producing lightning, such as developing thunderstorms and decaying anvils

  12. A New Methodology for Simultaneous Multi-layer Retrievals of Ice and Liquid Water Cloud Properties

    NASA Astrophysics Data System (ADS)

    Sourdeval, O.; Labonnote, L.; Baran, A. J.; Brogniez, G.

    2014-12-01

    It is widely recognized that the study of clouds has nowadays become one of the major concern of the climate research community. Consequently, a multitude of retrieval methodologies have been developed during the last decades in order to obtain accurate retrievals of cloud properties that can be supplied to climate models. Most of the current methodologies have proven to be satisfactory for separately retrieving ice or liquid cloud properties, but very few of them have attempted simultaneous retrievals of these two cloud types. Recent studies nevertheless show that the omission of one of these layers can have strong consequences on the retrievals and their accuracy. In this study, a new methodology that simultaneously retrieves the properties of ice and liquid clouds is presented. The optical thickness and the effective radius of up to two liquid cloud layers and the ice water path of one ice cloud layer are simultaneously retrieved, along with an accurate estimation of their uncertainties. Radiometric measurements ranging from the visible to the thermal infrared are used for performing the retrievals. In order to quantify the capabilities and limitations of our methodology, the results of a theoretical information content analysis are first presented. This analysis allows obtaining an a priori understanding of how much information should be expected on each of the retrieval parameters in different atmospheric conditions, and which set of channels is likely to provide this information. After such theoretical considerations, global retrievals corresponding to several months of A-Train data are presented. Comparisons of our retrievals with operational products from active and passive instruments are effectuated and show good global agreements. These comparisons are useful for validating our retrievals but also for testing how operational products can be influenced by multi-layer configurations.

  13. Clouds, Aerosols, and Precipitation in the Marine Boundary Layer: An Arm Mobile Facility Deployment

    SciTech Connect

    Wood, Robert; Wyant, Matthew; Bretherton, Christopher S.

    The Clouds, Aerosol, and Precipitation in the Marine Boundary Layer (CAP-MBL) deployment at Graciosa Island in the Azores generated a 21 month (April 2009-December 2010) comprehensive dataset documenting clouds, aerosols and precipitation using the Atmospheric Radiation Measurement (ARM) Mobile Facility (AMF). The scientific aim of the deployment is to gain improved understanding of the interactions of clouds, aerosols and precipitation in the marine boundary layer. Graciosa Island straddles the boundary between the subtropics and midlatitudes in the Northeast Atlantic Ocean, and consequently experiences a great diversity of meteorological and cloudiness conditions. Low clouds are the dominant cloud type, with stratocumulusmore » and cumulus occurring regularly. Approximately half of all clouds contained precipitation detectable as radar echoes below the cloud base. Radar and satellite observations show that clouds with tops from 1- 11 km contribute more or less equally to surface-measured precipitation at Graciosa. A wide range of aerosol conditions was sampled during the deployment consistent with the diversity of sources as indicated by back trajectory analysis. Preliminary findings suggest important two-way interactions between aerosols and clouds at Graciosa, with aerosols affecting light precipitation and cloud radiative properties while being controlled in part by precipitation scavenging. The data from at Graciosa are being compared with short-range forecasts made a variety of models. A pilot analysis with two climate and two weather forecast models shows that they reproduce the observed time-varying vertical structure of lower-tropospheric cloud fairly well, but the cloud-nucleating aerosol concentrations less well. The Graciosa site has been chosen to be a permanent fixed ARM site that became operational in October 2013.« less

  14. Clouds, aerosol, and precipitation in the Marine Boundary Layer: An ARM mobile facility deployment

    DOE PAGES

    Wood, Robert; Luke, Ed; Wyant, Matthew; ...

    2014-04-27

    The Clouds, Aerosol, and Precipitation in the Marine Boundary Layer (CAP-MBL) deployment at Graciosa Island in the Azores generated a 21-month (April 2009-December 2010) comprehensive dataset documenting clouds, aerosols, and precipitation using the Atmospheric Radiation Measurement Program (ARM) Mobile Facility (AMF). The scientific aim of the deployment is to gain improved understanding of the interactions of clouds, aerosols, and precipitation in the marine boundary layer. Graciosa Island straddles the boundary between the subtropics and midlatitudes in the Northeast Atlantic Ocean and consequently experiences a great diversity of meteorological and cloudiness conditions. Low clouds are the dominant cloud type, with stratocumulusmore » and cumulus occurring regularly. Approximately half of all clouds contained precipitation detectable as radar echoes below the cloud base. Radar and satellite observations show that clouds with tops from 1-11 km contribute more or less equally to surface-measured precipitation at Graciosa. A wide range of aerosol conditions was sampled during the deployment consistent with the diversity of sources as indicated by back-trajectory analysis. Preliminary findings suggest important two-way interactions between aerosols and clouds at Graciosa, with aerosols affecting light precipitation and cloud radiative properties while being controlled in part by precipitation scavenging.The data from Graciosa are being compared with short-range forecasts made with a variety of models. A pilot analysis with two climate and two weather forecast models shows that they reproduce the observed time-varying vertical structure of lower-tropospheric cloud fairly well but the cloud-nucleating aerosol concentrations less well. The Graciosa site has been chosen to be a permanent fixed ARM site that became operational in October 2013.« less

  15. Lidar measurements of boundary layers, aerosol scattering and clouds during project FIFE

    NASA Technical Reports Server (NTRS)

    Eloranta, Edwin W. (Principal Investigator)

    1995-01-01

    A detailed account of progress achieved under this grant funding is contained in five journal papers. The titles of these papers are: The calculation of area-averaged vertical profiles of the horizontal wind velocity using volume imaging lidar data; Volume imaging lidar observation of the convective structure surrounding the flight path of an instrumented aircraft; Convective boundary layer mean depths, cloud base altitudes, cloud top altitudes, cloud coverages, and cloud shadows obtained from Volume Imaging Lidar data; An accuracy analysis of the wind profiles calculated from Volume Imaging Lidar data; and Calculation of divergence and vertical motion from volume-imaging lidar data. Copies of these papers form the body of this report.

  16. Clouds, Aerosol, and Precipitation in the Marine Boundary Layer: An ARM Mobile Facility Deployment

    NASA Technical Reports Server (NTRS)

    Wood, Robert; Wyant, Matthew; Bretherton, Christopher S.; Remillard, Jasmine; Kollias, Pavlos; Fletcher, Jennifer; Stemmler, Jayson; de Szoeke, Simone; Yuter, Sandra; Miller, Matthew; hide

    2015-01-01

    Capsule: A 21-month deployment to Graciosa Island in the northeastern Atlantic Ocean is providing an unprecedented record of the clouds, aerosols and meteorology in a poorly-sampled remote marine environment The Clouds, Aerosol, and Precipitation in the Marine Boundary Layer (CAP-MBL) deployment at Graciosa Island in the Azores generated a 21 month (April 2009- December 2010) comprehensive dataset documenting clouds, aerosols and precipitation using the Atmospheric Radiation Measurement (ARM) Mobile Facility (AMF). The scientific aim of the deployment is to gain improved understanding of the interactions of clouds, aerosols and precipitation in the marine boundary layer. Graciosa Island straddles the boundary between the subtropics and midlatitudes in the Northeast Atlantic Ocean, and consequently experiences a great diversity of meteorological and cloudiness conditions. Low clouds are the dominant cloud type, with stratocumulus and cumulus occurring regularly. Approximately half of all clouds contained precipitation detectable as radar echoes below the cloud base. Radar and satellite observations show that clouds with tops from 1- 11 km contribute more or less equally to surface-measured precipitation at Graciosa. A wide range of aerosol conditions was sampled during the deployment consistent with the diversity of sources as indicated by back trajectory analysis. Preliminary findings suggest important two-way interactions between aerosols and clouds at Graciosa, with aerosols affecting light precipitation and cloud radiative properties while being controlled in part by precipitation scavenging. The data from at Graciosa are being compared with short-range forecasts made a variety of models. A pilot analysis with two climate and two weather forecast models shows that they reproduce the observed time-varying vertical structure of lower-tropospheric cloud fairly well, but the cloud-nucleating aerosol concentrations less well. The Graciosa site has been chosen to be a

  17. Seasonal simulations of the planetary boundary layer and boundary-layer stratocumulus clouds with a general circulation model

    NASA Technical Reports Server (NTRS)

    Randall, D. A.; Abeles, J. A.; Corsetti, T. G.

    1985-01-01

    The formulation of the planetary boundary layer (PBL) and stratocumulus parametrizations in the UCLA general circulation model (GCM) are briefly summarized, and extensive new results are presented illustrating some aspects of the simulated seasonal changes of the global distributions of PBL depth, stratocumulus cloudiness, cloud-top entrainment instability, the cumulus mass flux, and related fields. Results from three experiments designed to reveal the sensitivity of the GCM results to aspects of the PBL and stratocumulus parametrizations are presented. The GCM results show that the layer cloud instability appears to limit the extent of the marine subtropical stratocumulus regimes, and that instability frequently occurs in association with cumulus convection over land. Cumulus convection acts as a very significant sink of PBL mass throughout the tropics and over the midlatitude continents in winter.

  18. The character of drift spreading of artificial plasma clouds in the middle-latitude ionosphere

    NASA Astrophysics Data System (ADS)

    Blaunstein, N.

    1996-02-01

    Nonlinear equations describing the evolution of plasma clouds with real initial sizes, along and across the geomagnetic field B, which drift in the ionosphere in the presence of an ambient electric field and a neutral wind have been solved and analysed. An ionospheric model close to the real conditions of the middle-latitude ionosphere is introduced, taking into account the altitude dependence of the transport coefficients and background ionospheric plasma. The striation of the initial plasma cloud into a cluster of plasmoids, stretched along the field B, is obtained. The process of dispersive splitting of the initial plasma cloud can be understood in terms of gradient drift instability (GDI) as a most probable striation mechanism. The dependence of the characteristic time of dispersive splitting on the value of the ambient electric field, the initial plasma disturbance in the cloud and its initial sizes was investigated. The stretching criterion, necessary for the plasma cloud's striation is obtained. The possibility of the drift stabilization effect arising from azimuthal drift velocity shear, obtained by Drake et al. [1988], is examined for various parameters of the barium cloud and the background ionospheric conditions. A comparison with experimental data on the evolution of barium clouds in rocket experiments at the height of the lower ionosphere is made.

  19. Clouds, Aerosols, and Precipitation in the Marine Boundary Layer: An Arm Mobile Facility Deployment

    SciTech Connect

    Wood, Robert; Wyant, Matthew; Bretherton, Christopher S.

    The Clouds, Aerosol, and Precipitation in the Marine Boundary Layer (CAP-MBL) 38 deployment at Graciosa Island in the Azores generated a 21 month (April 2009-December 2010) 39 comprehensive dataset documenting clouds, aerosols and precipitation using the Atmospheric 40 Radiation Measurement (ARM) Mobile Facility (AMF). The scientific aim of the deployment is 41 to gain improved understanding of the interactions of clouds, aerosols and precipitation in the 42 marine boundary layer. 43 Graciosa Island straddles the boundary between the subtropics and midlatitudes in the 44 Northeast Atlantic Ocean, and consequently experiences a great diversity of meteorological and 45 cloudiness conditions. Lowmore » clouds are the dominant cloud type, with stratocumulus and cumulus 46 occurring regularly. Approximately half of all clouds contained precipitation detectable as radar 47 echoes below the cloud base. Radar and satellite observations show that clouds with tops from 1-48 11 km contribute more or less equally to surface-measured precipitation at Graciosa. A wide 49 range of aerosol conditions was sampled during the deployment consistent with the diversity of 50 sources as indicated by back trajectory analysis. Preliminary findings suggest important two-way 51 interactions between aerosols and clouds at Graciosa, with aerosols affecting light precipitation 52 and cloud radiative properties while being controlled in part by precipitation scavenging. 53 The data from at Graciosa are being compared with short-range forecasts made a variety 54 of models. A pilot analysis with two climate and two weather forecast models shows that they 55 reproduce the observed time-varying vertical structure of lower-tropospheric cloud fairly well, 56 but the cloud-nucleating aerosol concentrations less well. The Graciosa site has been chosen to 57 be a long-term ARM site that became operational in October 2013.« less

  20. Marine boundary layer cloud regimes and POC formation in an LES coupled to a bulk aerosol scheme

    NASA Astrophysics Data System (ADS)

    Berner, A. H.; Bretherton, C. S.; Wood, R.; Muhlbauer, A.

    2013-07-01

    A large-eddy simulation (LES) coupled to a new bulk aerosol scheme is used to study long-lived regimes of aerosol-boundary layer cloud-precipitation interaction and the development of pockets of open cells (POCs) in subtropical stratocumulus cloud layers. The aerosol scheme prognoses mass and number concentration of a single log-normal accumulation mode with surface and entrainment sources, evolving subject to processing of activated aerosol and scavenging of dry aerosol by cloud and rain. The LES with the aerosol scheme is applied to a range of steadily-forced simulations idealized from a well-observed POC case. The long-term system evolution is explored with extended two-dimensional simulations of up to 20 days, mostly with diurnally-averaged insolation. One three-dimensional two-day simulation confirms the initial development of the corresponding two-dimensional case. With weak mean subsidence, an initially aerosol-rich mixed layer deepens, the capping stratocumulus cloud slowly thickens and increasingly depletes aerosol via precipitation accretion, then the boundary layer transitions within a few hours into an open-cell regime with scattered precipitating cumuli, in which entrainment is much weaker. The inversion slowly collapses for several days until the cumulus clouds are too shallow to efficiently precipitate. Inversion cloud then reforms and radiatively drives renewed entrainment, allowing the boundary layer to deepen and become more aerosol-rich, until the stratocumulus layer thickens enough to undergo another cycle of open-cell formation. If mean subsidence is stronger, the stratocumulus never thickens enough to initiate drizzle and settles into a steady state. With lower initial aerosol concentrations, this system quickly transitions into open cells, collapses, and redevelops into a different steady state with a shallow, optically thin cloud layer. In these steady states, interstitial scavenging by cloud droplets is the main sink of aerosol number. The

  1. Raman lidar measurement of water vapor and ice clouds associated with Asian dust layer over Tsukuba, Japan

    NASA Astrophysics Data System (ADS)

    Sakai, Tetsu; Nagai, Tomohiro; Nakazato, Masahisa; Matsumura, Takatsugu

    2004-03-01

    The vertical distributions of particle extinction, backscattering, depolarization, and water vapor mixing ratio were measured using a Raman lidar over Tsukuba (36.1°N, 140.1°E), Japan, on 23-24 April 2001. Ice clouds associated with the Asian dust layer were observed at an altitude of ~6-9 km. The relative humidities in the cloud layer were close to the ice saturation values and the temperature at the top of the cloud layer was ~-35°C, suggesting that the Asian dust acted as ice nuclei at the high temperatures. The meteorological analysis suggested that the ice-saturated region was formed near the top of the dust layer where the moist air ascended in slantwise fashion above the cold-frontal zone associated with extratropical cyclone.

  2. Validation of a radiosonde-based cloud layer detection method against a ground-based remote sensing method at multiple ARM sites

    NASA Astrophysics Data System (ADS)

    Zhang, Jinqiang; Li, Zhanqing; Chen, Hongbin; Cribb, Maureen

    2013-01-01

    Cloud vertical structure is a key quantity in meteorological and climate studies, but it is also among the most difficult quantities to observe. In this study, we develop a long-term (10 years) radiosonde-based cloud profile product for the U.S. Department of Energy's Atmospheric Radiation Measurement (ARM) program Southern Great Plains (SGP), Tropical Western Pacific (TWP), and North Slope of Alaska (NSA) sites and a shorter-term product for the ARM Mobile Facility (AMF) deployed in Shouxian, Anhui Province, China (AMF-China). The AMF-China site was in operation from 14 May to 28 December 2008; the ARM sites have been collecting data for over 15 years. The Active Remote Sensing of Cloud (ARSCL) value-added product (VAP), which combines data from the 95-GHz W-band ARM Cloud Radar (WACR) and/or the 35-GHz Millimeter Microwave Cloud Radar (MMCR), is used in this study to validate the radiosonde-based cloud layer retrieval method. The performance of the radiosonde-based cloud layer retrieval method applied to data from different climate regimes is evaluated. Overall, cloud layers derived from the ARSCL VAP and radiosonde data agree very well at the SGP and AMF-China sites. At the TWP and NSA sites, the radiosonde tends to detect more cloud layers in the upper troposphere.

  3. Impact of Low Level Clouds on radiative and turbulent surface flux in southern West Africa

    NASA Astrophysics Data System (ADS)

    Lohou, Fabienne; Kalthoff, Norbert; Dione, Cheikh; Lothon, Marie; Adler, Bianca; Babic, Karmen; Pedruzo-Bagazgoitia, Xabier; Vila-Guerau De Arellano, Jordi

    2017-04-01

    During the monsoon season in West Africa, low-level clouds form almost every night and break up between 0900 and the middle of the afternoon depending on the day. The break-up of these clouds leads to the formation of boundary-layer cumuli clouds, which can sometimes evolve into deep convection. The low-level clouds have a strong impact on the radiation and energy budget at the surface and consequently on the humidity in the boundary layer and the afternoon convection. During the DACCIWA ground campaign, which took place in June and July 2016, three supersites in Benin, Ghana, and Nigeria were instrumented to document the conditions within the lower troposphere including the cloud layers. Radiative and turbulent fluxes were measured at different places by several surface stations jointly with low-level cloud occurrence during 50 days. These datasets enable the analysis of modifications in the diurnal cycle of the radiative and turbulent surface flux induced by the formation and presence of the low-level clouds. The final objective of this study is to estimate the error made in some NWP simulations when the diurnal cycle of low-level clouds is poorly represented or not represented at all.

  4. Lagrangian large eddy simulations of boundary layer clouds on ERA-Interim and ERA5 trajectories

    NASA Astrophysics Data System (ADS)

    Kazil, J.; Feingold, G.; Yamaguchi, T.

    2017-12-01

    This exploratory study examines Lagrangian large eddy simulations of boundary layer clouds along wind trajectories from the ERA-Interim and ERA5 reanalyses. The study is motivated by the need for statistically representative sets of high resolution simulations of cloud field evolution in realistic meteorological conditions. The study will serve as a foundation for the investigation of biomass burning effects on the transition from stratocumulus to shallow cumulus clouds in the South-East Atlantic. Trajectories that pass through a location with radiosonde data (St. Helena) and which exhibit a well-defined cloud structure and evolution were identified in satellite imagery, and sea surface temperature and atmospheric vertical profiles along the trajectories were extracted from the reanalysis data sets. The System for Atmospheric Modeling (SAM) simulated boundary layer turbulence and cloud properties along the trajectories. Mean temperature and moisture (in the free troposphere) and mean wind speed (at all levels) were nudged towards the reanalysis data. Atmospheric and cloud properties in the large eddy simulations were compared with those from the reanalysis products, and evaluated with satellite imagery and radiosonde data. Simulations using ERA-Interim data and the higher resolution ERA5 data are contrasted.

  5. Study of Venus' cloud layers by polarimetry using SPICAV/VEx

    NASA Astrophysics Data System (ADS)

    Rossi, Loïc; Marcq, Emmanuel; Montmessin, Franck; Bertaux, Jean-Loup; Korablev, Oleg; Fedorova, Anna

    2013-04-01

    The study of Venus's cloud layers is important in order to understand the structure, radiative balance and dynamics of the Venusian atmosphere. The main cloud layers between 50 and 70km are thought to consist in ~ 1μm radius droplets of a H2SO4-H2O solution. Nevertheless, the composition and the size distribution of the droplets are difficult to constrain more precisely. The polarization measurements have given great results in the determination of the constituents of the haze. In the early 1980s, Kawabata et al.(1980) used the polarization data from the OCPP instrument on the spacecraft Pioneer Venus to constrain the properties of the haze. They obtained a refractive index of 1.45 ± 0.04 at ? = 550nm and an effective radius of 0.23 ± 0.04μm, with a normalized size distribution variance of 0.18 ± 0.1. Our work aims to reproduce the method used by Kawabata et al. by writing a Lorentz-Mie scattering model and apply it to the so far unexploited polarization data of the SPICAV-IR instrument on-board ESA's Venus Express in order to better constrain haze and cloud particles at the top of Venus's clouds, as well as their spatial and temporal variability. We introduce here the model we developed, based on the BH-MIE scattering model. Taking into account the same size distribution of droplets as Kawabata et al., we obtained the polarization degree after a single Mie scattering by a haze at all phase angles given the effective radius and variance of the distribution and the refractive index of the droplets. Our model seems consistent as it reproduces the polarization degree modeled by Kawabata et al. We also present the first application of our model to the SPICAV-IR data under the single scattering assumption. Hence we can confirm the mean constraints on the size and refractive index of the haze and cloud droplets. In the near future, we then aim to extend our study of the polarization data by integrating our model into a radiative transfer model which will take into

  6. Impacts of solar-absorbing aerosol layers on the transition of stratocumulus to trade cumulus clouds

    NASA Astrophysics Data System (ADS)

    Zhou, Xiaoli; Ackerman, Andrew S.; Fridlind, Ann M.; Wood, Robert; Kollias, Pavlos

    2017-10-01

    The effects of an initially overlying layer of solar-absorbing aerosol on the transition of stratocumulus to trade cumulus clouds are examined using large-eddy simulations. For lightly drizzling cloud the transition is generally hastened, resulting mainly from increased cloud droplet number concentration (Nc) induced by entrained aerosol. The increased Nc slows sedimentation of cloud droplets and shortens their relaxation time for diffusional growth, both of which accelerate entrainment of overlying air and thereby stratocumulus breakup. However, the decrease in albedo from cloud breakup is more than offset by redistributing cloud water over a greater number of droplets, such that the diurnal-average shortwave forcing at the top of the atmosphere is negative. The negative radiative forcing is enhanced by sizable longwave contributions, which result from the greater cloud breakup and a reduced boundary layer height associated with aerosol heating. A perturbation of moisture instead of aerosol aloft leads to a greater liquid water path and a more gradual transition. Adding absorbing aerosol to that atmosphere results in substantial reductions in liquid water path (LWP) and cloud cover that lead to positive shortwave and negative longwave forcings on average canceling each other. Only for heavily drizzling clouds is the breakup delayed, as inhibition of precipitation overcomes cloud water loss from enhanced entrainment. Considering these simulations as an imperfect proxy for biomass burning plumes influencing Namibian stratocumulus, we expect regional indirect plus semi-direct forcings to be substantially negative to negligible at the top of the atmosphere, with its magnitude sensitive to background and perturbation properties.

  7. Impacts of Solar-Absorbing Aerosol Layers on the Transition of Stratocumulus to Trade Cumulus Clouds

    NASA Technical Reports Server (NTRS)

    Zhou, Xiaoli; Ackerman, Andrew S.; Fridlind, Ann M.; Wood, Robert; Kollias, Pavlos

    2017-01-01

    The effects of an initially overlying layer of solar-absorbing aerosol on the transition of stratocumulus to trade cumulus clouds are examined using large-eddy simulations. For lightly drizzling cloud the transition is generally hastened, resulting mainly from increased cloud droplet number concentration (Nc) induced by entrained aerosol. The increased Nc slows sedimentation of cloud droplets and shortens their relaxation time for diffusional growth, both of which accelerate entrainment of overlying air and thereby stratocumulus breakup. However, the decrease in albedo from cloud breakup is more than offset by redistributing cloud water over a greater number of droplets, such that the diurnal-average shortwave forcing at the top of the atmosphere is negative. The negative radiative forcing is enhanced by sizable longwave contributions, which result from the greater cloud breakup and a reduced boundary layer height associated with aerosol heating. A perturbation of moisture instead of aerosol aloft leads to a greater liquid water path and a more gradual transition. Adding absorbing aerosol to that atmosphere results in substantial reductions in liquid water path (LWP) and cloud cover that lead to positive short-wave and negative longwave forcings on average canceling each other. Only for heavily drizzling clouds is the breakup delayed, as inhibition of precipitation overcomes cloud water loss from enhanced entrainment. Considering these simulations as an imperfect proxy for biomass burning plumes influencing Namibian stratocumulus, we expect regional indirect plus semi-direct forcings to be substantially negative to negligible at the top of the atmosphere, with its magnitude sensitive to background and perturbation properties.

  8. Cirrus Cloud Retrieval Using Infrared Sounding Data: Multilevel Cloud Errors.

    NASA Astrophysics Data System (ADS)

    Baum, Bryan A.; Wielicki, Bruce A.

    1994-01-01

    In this study we perform an error analysis for cloud-top pressure retrieval using the High-Resolution Infrared Radiometric Sounder (HIRS/2) 15-µm CO2 channels for the two-layer case of transmissive cirrus overlying an overcast, opaque stratiform cloud. This analysis includes standard deviation and bias error due to instrument noise and the presence of two cloud layers, the lower of which is opaque. Instantaneous cloud pressure retrieval errors are determined for a range of cloud amounts (0.1 1.0) and cloud-top pressures (850250 mb). Large cloud-top pressure retrieval errors are found to occur when a lower opaque layer is present underneath an upper transmissive cloud layer in the satellite field of view (FOV). Errors tend to increase with decreasing upper-cloud elective cloud amount and with decreasing cloud height (increasing pressure). Errors in retrieved upper-cloud pressure result in corresponding errors in derived effective cloud amount. For the case in which a HIRS FOV has two distinct cloud layers, the difference between the retrieved and actual cloud-top pressure is positive in all casts, meaning that the retrieved upper-cloud height is lower than the actual upper-cloud height. In addition, errors in retrieved cloud pressure are found to depend upon the lapse rate between the low-level cloud top and the surface. We examined which sounder channel combinations would minimize the total errors in derived cirrus cloud height caused by instrument noise and by the presence of a lower-level cloud. We find that while the sounding channels that peak between 700 and 1000 mb minimize random errors, the sounding channels that peak at 300—500 mb minimize bias errors. For a cloud climatology, the bias errors are most critical.

  9. Structure of the middle atmosphere of Venus

    NASA Astrophysics Data System (ADS)

    Zasova, Ludmila

    Middle atmosphere of Venus (55-100 km), its mesosphere, is the important layer of atmosphere, where 70 % of the solar energy is absorbed. Most of this absorption takes place in the upper clouds in the altitude range 58-68 km in the spectral range 0.32-0.5 µm. It leads to generation of the thermal tides, playing important role in support of the superrotation. In the frame of COSPAR model VIRA (ASR, 11,1985) the model of the thermal structure of the middle atmosphere was constructed for 5 latitude ranges, based mainly on the Pioneer Venus ORO and OIR data. Using Venera-15 Fourier Spectrometry data, which allow to retrieve the temperature and aerosol profiles in a self consistent way from each spectrum, we enable to update the model of the middle atmosphere, including the local time variation of the temperature for VIRA latitude ranges (Cosmic Research, 44, 4, 2006). From Venera-15 data it was shown that variation of temperature in the middle atmosphere is well described by thermal tides with harmonics 1, 1/2, 1/3, 1/4 Venusian day, the amplitudes and phases of which depend on latitude and altitude. The model of the upper clouds (VIRA) may also be updated using Venera-15 data. It was shown that the main latitude trend is the decreasing of the upper cloud boundary from 68 km at low latitudes to 60-62 km at high latitudes. Local time variation has a solar related dependence: 1 and 1/2 day components were revealed. Venus Express continues to obtain a lot of data, which may be used for the improvement of the model of the middle atmosphere and the clouds.

  10. Mixing Layer Formation near the Tropopause Due to Gravity Wave Critical Level Interactions in a Cloud-Resolving Model.

    NASA Astrophysics Data System (ADS)

    Moustaoui, Mohamed; Joseph, Binson; Teitelbaum, Hector

    2004-12-01

    A plausible mechanism for the formation of mixing layers in the lower stratosphere above regions of tropical convection is demonstrated numerically using high-resolution, two-dimensional (2D), anelastic, nonlinear, cloud-resolving simulations. One noteworthy point is that the mixing layer simulated in this study is free of anvil clouds and well above the cloud anvil top located in the upper troposphere. Hence, the present mechanism is complementary to the well-known process by which overshooting cloud turrets causes mixing within stratospheric anvil clouds. The paper is organized as a case study verifying the proposed mechanism using atmospheric soundings obtained during the Central Equatorial Pacific Experiment (CEPEX), when several such mixing layers, devoid of anvil clouds, had been observed. The basic dynamical ingredient of the present mechanism is (quasi stationary) gravity wave critical level interactions, occurring in association with a reversal of stratospheric westerlies to easterlies below the tropopause region. The robustness of the results is shown through simulations at different resolutions. The insensitivity of the qualitative results to the details of the subgrid scheme is also evinced through further simulations with and without subgrid mixing terms. From Lagrangian reconstruction of (passive) ozone fields, it is shown that the mixing layer is formed kinematically through advection by the resolved-scale (nonlinear) velocity field.


  11. Analytic Closed-Form Solution of a Mixed Layer Model for Stratocumulus Clouds

    NASA Astrophysics Data System (ADS)

    Akyurek, Bengu Ozge

    Stratocumulus clouds play an important role in climate cooling and are hard to predict using global climate and weather forecast models. Thus, previous studies in the literature use observations and numerical simulation tools, such as large-eddy simulation (LES), to solve the governing equations for the evolution of stratocumulus clouds. In contrast to the previous works, this work provides an analytic closed-form solution to the cloud thickness evolution of stratocumulus clouds in a mixed-layer model framework. With a focus on application over coastal lands, the diurnal cycle of cloud thickness and whether or not clouds dissipate are of particular interest. An analytic solution enables the sensitivity analysis of implicitly interdependent variables and extrema analysis of cloud variables that are hard to achieve using numerical solutions. In this work, the sensitivity of inversion height, cloud-base height, and cloud thickness with respect to initial and boundary conditions, such as Bowen ratio, subsidence, surface temperature, and initial inversion height, are studied. A critical initial cloud thickness value that can be dissipated pre- and post-sunrise is provided. Furthermore, an extrema analysis is provided to obtain the minima and maxima of the inversion height and cloud thickness within 24 h. The proposed solution is validated against LES results under the same initial and boundary conditions. Then, the proposed analytic framework is extended to incorporate multiple vertical columns that are coupled by advection through wind flow. This enables a bridge between the micro-scale and the mesoscale relations. The effect of advection on cloud evolution is studied and a sensitivity analysis is provided.

  12. RACORO Continental Boundary Layer Cloud Investigations: 1. Case Study Development and Ensemble Large-Scale Forcings

    NASA Technical Reports Server (NTRS)

    Vogelmann, Andrew M.; Fridlind, Ann M.; Toto, Tami; Endo, Satoshi; Lin, Wuyin; Wang, Jian; Feng, Sha; Zhang, Yunyan; Turner, David D.; Liu, Yangang; hide

    2015-01-01

    Observation-based modeling case studies of continental boundary layer clouds have been developed to study cloudy boundary layers, aerosol influences upon them, and their representation in cloud- and global-scale models. Three 60 h case study periods span the temporal evolution of cumulus, stratiform, and drizzling boundary layer cloud systems, representing mixed and transitional states rather than idealized or canonical cases. Based on in situ measurements from the Routine AAF (Atmospheric Radiation Measurement (ARM) Aerial Facility) CLOWD (Clouds with Low Optical Water Depth) Optical Radiative Observations (RACORO) field campaign and remote sensing observations, the cases are designed with a modular configuration to simplify use in large-eddy simulations (LES) and single-column models. Aircraft measurements of aerosol number size distribution are fit to lognormal functions for concise representation in models. Values of the aerosol hygroscopicity parameter, kappa, are derived from observations to be approximately 0.10, which are lower than the 0.3 typical over continents and suggestive of a large aerosol organic fraction. Ensemble large-scale forcing data sets are derived from the ARM variational analysis, European Centre for Medium-Range Weather Forecasts, and a multiscale data assimilation system. The forcings are assessed through comparison of measured bulk atmospheric and cloud properties to those computed in "trial" large-eddy simulations, where more efficient run times are enabled through modest reductions in grid resolution and domain size compared to the full-sized LES grid. Simulations capture many of the general features observed, but the state-of-the-art forcings were limited at representing details of cloud onset, and tight gradients and high-resolution transients of importance. Methods for improving the initial conditions and forcings are discussed. The cases developed are available to the general modeling community for studying continental boundary

  13. RACORO continental boundary layer cloud investigations: 1. Case study development and ensemble large-scale forcings

    NASA Astrophysics Data System (ADS)

    Vogelmann, Andrew M.; Fridlind, Ann M.; Toto, Tami; Endo, Satoshi; Lin, Wuyin; Wang, Jian; Feng, Sha; Zhang, Yunyan; Turner, David D.; Liu, Yangang; Li, Zhijin; Xie, Shaocheng; Ackerman, Andrew S.; Zhang, Minghua; Khairoutdinov, Marat

    2015-06-01

    Observation-based modeling case studies of continental boundary layer clouds have been developed to study cloudy boundary layers, aerosol influences upon them, and their representation in cloud- and global-scale models. Three 60 h case study periods span the temporal evolution of cumulus, stratiform, and drizzling boundary layer cloud systems, representing mixed and transitional states rather than idealized or canonical cases. Based on in situ measurements from the Routine AAF (Atmospheric Radiation Measurement (ARM) Aerial Facility) CLOWD (Clouds with Low Optical Water Depth) Optical Radiative Observations (RACORO) field campaign and remote sensing observations, the cases are designed with a modular configuration to simplify use in large-eddy simulations (LES) and single-column models. Aircraft measurements of aerosol number size distribution are fit to lognormal functions for concise representation in models. Values of the aerosol hygroscopicity parameter, κ, are derived from observations to be 0.10, which are lower than the 0.3 typical over continents and suggestive of a large aerosol organic fraction. Ensemble large-scale forcing data sets are derived from the ARM variational analysis, European Centre for Medium-Range Weather Forecasts, and a multiscale data assimilation system. The forcings are assessed through comparison of measured bulk atmospheric and cloud properties to those computed in "trial" large-eddy simulations, where more efficient run times are enabled through modest reductions in grid resolution and domain size compared to the full-sized LES grid. Simulations capture many of the general features observed, but the state-of-the-art forcings were limited at representing details of cloud onset, and tight gradients and high-resolution transients of importance. Methods for improving the initial conditions and forcings are discussed. The cases developed are available to the general modeling community for studying continental boundary clouds.

  14. RACORO continental boundary layer cloud investigations. 2. Large-eddy simulations of cumulus clouds and evaluation with in-situ and ground-based observations

    DOE PAGES

    Endo, Satoshi; Fridlind, Ann M.; Lin, Wuyin; ...

    2015-06-19

    A 60-hour case study of continental boundary layer cumulus clouds is examined using two large-eddy simulation (LES) models. The case is based on observations obtained during the RACORO Campaign (Routine Atmospheric Radiation Measurement [ARM] Aerial Facility [AAF] Clouds with Low Optical Water Depths [CLOWD] Optical Radiative Observations) at the ARM Climate Research Facility's Southern Great Plains site. The LES models are driven by continuous large-scale and surface forcings, and are constrained by multi-modal and temporally varying aerosol number size distribution profiles derived from aircraft observations. We compare simulated cloud macrophysical and microphysical properties with ground-based remote sensing and aircraft observations.more » The LES simulations capture the observed transitions of the evolving cumulus-topped boundary layers during the three daytime periods, and generally reproduce variations of droplet number concentration with liquid water content (LWC), corresponding to the gradient between the cloud centers and cloud edges at given heights. The observed LWC values fall within the range of simulated values; the observed droplet number concentrations are commonly higher than simulated, but differences remain on par with potential estimation errors in the aircraft measurements. Sensitivity studies examine the influences of bin microphysics versus bulk microphysics, aerosol advection, supersaturation treatment, and aerosol hygroscopicity. Simulated macrophysical cloud properties are found to be insensitive in this non-precipitating case, but microphysical properties are especially sensitive to bulk microphysics supersaturation treatment and aerosol hygroscopicity.« less

  15. Can We Use Single-Column Models for Understanding the Boundary Layer Cloud-Climate Feedback?

    NASA Astrophysics Data System (ADS)

    Dal Gesso, S.; Neggers, R. A. J.

    2018-02-01

    This study explores how to drive Single-Column Models (SCMs) with existing data sets of General Circulation Model (GCM) outputs, with the aim of studying the boundary layer cloud response to climate change in the marine subtropical trade wind regime. The EC-EARTH SCM is driven with the large-scale tendencies and boundary conditions as derived from two different data sets, consisting of high-frequency outputs of GCM simulations. SCM simulations are performed near Barbados Cloud Observatory in the dry season (January-April), when fair-weather cumulus is the dominant low-cloud regime. This climate regime is characterized by a near equilibrium in the free troposphere between the long-wave radiative cooling and the large-scale advection of warm air. In the SCM, this equilibrium is ensured by scaling the monthly mean dynamical tendency of temperature and humidity such that it balances that of the model physics in the free troposphere. In this setup, the high-frequency variability in the forcing is maintained, and the boundary layer physics acts freely. This technique yields representative cloud amount and structure in the SCM for the current climate. Furthermore, the cloud response to a sea surface warming of 4 K as produced by the SCM is consistent with that of the forcing GCM.

  16. Impacts of solar-absorbing aerosol layers on the transition of stratocumulus to trade cumulus clouds

    DOE PAGES

    Zhou, Xiaoli; Ackerman, Andrew S.; Fridlind, Ann M.; ...

    2017-10-26

    Here, the effects of an initially overlying layer of solar-absorbing aerosol on the transition of stratocumulus to trade cumulus clouds are examined using large-eddy simulations. For lightly drizzling cloud the transition is generally hastened, resulting mainly from increased cloud droplet number concentration ( N c) induced by entrained aerosol. The increased N c slows sedimentation of cloud droplets and shortens their relaxation time for diffusional growth, both of which accelerate entrainment of overlying air and thereby stratocumulus breakup. However, the decrease in albedo from cloud breakup is more than offset by redistributing cloud water over a greater number of droplets,more » such that the diurnal-average shortwave forcing at the top of the atmosphere is negative. The negative radiative forcing is enhanced by sizable longwave contributions, which result from the greater cloud breakup and a reduced boundary layer height associated with aerosol heating. A perturbation of moisture instead of aerosol aloft leads to a greater liquid water path and a more gradual transition. Adding absorbing aerosol to that atmosphere results in substantial reductions in liquid water path (LWP) and cloud cover that lead to positive shortwave and negative longwave forcings on average canceling each other. Only for heavily drizzling clouds is the breakup delayed, as inhibition of precipitation overcomes cloud water loss from enhanced entrainment. Considering these simulations as an imperfect proxy for biomass burning plumes influencing Namibian stratocumulus, we expect regional indirect plus semi-direct forcings to be substantially negative to negligible at the top of the atmosphere, with its magnitude sensitive to background and perturbation properties.« less

  17. Impacts of solar-absorbing aerosol layers on the transition of stratocumulus to trade cumulus clouds

    SciTech Connect

    Zhou, Xiaoli; Ackerman, Andrew S.; Fridlind, Ann M.

    Here, the effects of an initially overlying layer of solar-absorbing aerosol on the transition of stratocumulus to trade cumulus clouds are examined using large-eddy simulations. For lightly drizzling cloud the transition is generally hastened, resulting mainly from increased cloud droplet number concentration ( N c) induced by entrained aerosol. The increased N c slows sedimentation of cloud droplets and shortens their relaxation time for diffusional growth, both of which accelerate entrainment of overlying air and thereby stratocumulus breakup. However, the decrease in albedo from cloud breakup is more than offset by redistributing cloud water over a greater number of droplets,more » such that the diurnal-average shortwave forcing at the top of the atmosphere is negative. The negative radiative forcing is enhanced by sizable longwave contributions, which result from the greater cloud breakup and a reduced boundary layer height associated with aerosol heating. A perturbation of moisture instead of aerosol aloft leads to a greater liquid water path and a more gradual transition. Adding absorbing aerosol to that atmosphere results in substantial reductions in liquid water path (LWP) and cloud cover that lead to positive shortwave and negative longwave forcings on average canceling each other. Only for heavily drizzling clouds is the breakup delayed, as inhibition of precipitation overcomes cloud water loss from enhanced entrainment. Considering these simulations as an imperfect proxy for biomass burning plumes influencing Namibian stratocumulus, we expect regional indirect plus semi-direct forcings to be substantially negative to negligible at the top of the atmosphere, with its magnitude sensitive to background and perturbation properties.« less

  18. Temperature Control of the Variability of Tropical Tropopause Layer Cirrus Clouds

    NASA Astrophysics Data System (ADS)

    Tseng, Hsiu-Hui; Fu, Qiang

    2017-10-01

    This study examines the temperature control of variability of tropical tropopause layer (TTL) cirrus clouds (i.e., clouds with bases higher than 14.5 km) by using 8 years (2006-2014) of observations from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) and Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC). It is found that the temporal variability of vertical structure of TTL cirrus cloud fraction averaged between 15°N and 15°S can be well explained by the vertical temperature gradient below 17.5 km but by the local temperature above for both seasonal and interannual time scales. It is also found that the TTL cirrus cloud fraction at a given altitude is best correlated with the temperature at a higher altitude and this vertical displacement increases with a decrease of the cirrus altitude. It is shown that the TTL cirrus cloud fractions at all altitudes are significantly correlated with tropical cold point tropopause (CPT) temperature. The plausible mechanisms that might be responsible for the observed relations between TTL cirrus fraction and temperature-based variables are discussed, which include ice particle sediments, cooling associated with wave propagations, change of atmospheric stability, and vertical gradient of water vapor mixing ratio. We further examine the spatial covariability of TTL total cirrus cloud fraction and CPT temperature for the interannual time scale. It is found that the El Niño-Southern Oscillation and quasi-biennial oscillation are the leading factors in controlling the spatial variability of the TTL cirrus clouds and temperatures.

  19. 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.

  20. The GCM-Oriented CALIPSO Cloud Product (CALIPSO-GOCCP)

    NASA Astrophysics Data System (ADS)

    Chepfer, H.; Bony, S.; Winker, D.; Cesana, G.; Dufresne, J. L.; Minnis, P.; Stubenrauch, C. J.; Zeng, S.

    2010-01-01

    This article presents the GCM-Oriented Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) Cloud Product (GOCCP) designed to evaluate the cloudiness simulated by general circulation models (GCMs). For this purpose, Cloud-Aerosol Lidar with Orthogonal Polarization L1 data are processed following the same steps as in a lidar simulator used to diagnose the model cloud cover that CALIPSO would observe from space if the satellite was flying above an atmosphere similar to that predicted by the GCM. Instantaneous profiles of the lidar scattering ratio (SR) are first computed at the highest horizontal resolution of the data but at the vertical resolution typical of current GCMs, and then cloud diagnostics are inferred from these profiles: vertical distribution of cloud fraction, horizontal distribution of low, middle, high, and total cloud fractions, instantaneous SR profiles, and SR histograms as a function of height. Results are presented for different seasons (January-March 2007-2008 and June-August 2006-2008), and their sensitivity to parameters of the lidar simulator is investigated. It is shown that the choice of the vertical resolution and of the SR threshold value used for cloud detection can modify the cloud fraction by up to 0.20, particularly in the shallow cumulus regions. The tropical marine low-level cloud fraction is larger during nighttime (by up to 0.15) than during daytime. The histograms of SR characterize the cloud types encountered in different regions. The GOCCP high-level cloud amount is similar to that from the TIROS Operational Vertical Sounder (TOVS) and the Atmospheric Infrared Sounder (AIRS). The low-level and middle-level cloud fractions are larger than those derived from passive remote sensing (International Satellite Cloud Climatology Project, Moderate-Resolution Imaging Spectroradiometer-Cloud and Earth Radiant Energy System Polarization and Directionality of Earth Reflectances, TOVS Path B, AIRS-Laboratoire de M

  1. Cloud cover anomalies at middle latitudes: Links to troposphere dynamics and solar variability

    NASA Astrophysics Data System (ADS)

    Veretenenko, S.; Ogurtsov, M.

    2016-11-01

    In this work we study links between low cloud anomalies (LCA) at middle latitudes of the Northern and Southern hemispheres and galactic cosmic ray (GCR) variations used as a proxy of solar variability on the decadal time scale. It was shown that these links are not direct, but realized through GCR/solar activity phenomena influence on the development of extratropical baric systems (cyclones and troughs) which form cloud field. The violation of a positive correlation between LCA and GCR intensity which was observed in the 1980s-1990s occurred simultaneously in the Northern and Southern hemispheres in the early 2000s and coincided with the sign reversal of GCR effects on troposphere circulation. It was suggested that a possible reason for the correlation reversal between cyclonic activity at middle latitudes and GCR fluxes is the change of the stratospheric polar vortex intensity which influences significantly the troposphere-stratosphere coupling. The evidences for a noticeable weakening of the polar vortices in the Arctic and Antarctic stratosphere in the early 2000s are provided. The results obtained suggest an important role of the polar vortex evolution as a reason for a temporal variability of solar activity effects on the lower atmosphere.

  2. Three-dimensional turbulence-resolving modeling of the Venusian cloud layer and induced gravity waves

    NASA Astrophysics Data System (ADS)

    Lefèvre, Maxence; Spiga, Aymeric; Lebonnois, Sébastien

    2017-04-01

    The impact of the cloud convective layer of the atmosphere of Venus on the global circulation remains unclear. The recent observations of gravity waves at the top of the cloud by the Venus Express mission provided some answers. These waves are not resolved at the scale of global circulation models (GCM), therefore we developed an unprecedented 3D turbulence-resolving Large-Eddy Simulations (LES) Venusian model (Lefèvre et al, 2016 JGR Planets) using the Weather Research and Forecast terrestrial model. The forcing consists of three different heating rates : two radiative ones for solar and infrared and one associated with the adiabatic cooling/warming of the global circulation. The rates are extracted from the Laboratoire de Météorlogie Dynamique (LMD) Venus GCM using two different cloud models. Thus we are able to characterize the convection and associated gravity waves in function of latitude and local time. To assess the impact of the global circulation on the convective layer, we used rates from a 1D radiative-convective model. The resolved layer, taking place between 1.0 105 and 3.8 104 Pa (48-53 km), is organized as polygonal closed cells of about 10 km wide with vertical wind of several meters per second. The convection emits gravity waves both above and below the convective layer leading to temperature perturbations of several tenths of Kelvin with vertical wavelength between 1 and 3 km and horizontal wavelength from 1 to 10 km. The thickness of the convective layer and the amplitudes of waves are consistent with observations, though slightly underestimated. The global dynamics heating greatly modify the convective layer.

  3. Three-dimensional turbulence-resolving modeling of the Venusian cloud layer and induced gravity waves

    NASA Astrophysics Data System (ADS)

    Lefèvre, Maxence; Spiga, Aymeric; Lebonnois, Sébastien

    2017-01-01

    The impact of the cloud convective layer of the atmosphere of Venus on the global circulation remains unclear. The recent observations of gravity waves at the top of the cloud by the Venus Express mission provided some answers. These waves are not resolved at the scale of global circulation models (GCM); therefore, we developed an unprecedented 3-D turbulence-resolving large-eddy simulations (LES) Venusian model using the Weather Research and Forecast terrestrial model. The forcing consists of three different heating rates: two radiative ones for solar and infrared and one associated with the adiabatic cooling/warming of the global circulation. The rates are extracted from the Laboratoire de Météorlogie Dynamique Venus GCM using two different cloud models. Thus, we are able to characterize the convection and associated gravity waves in function of latitude and local time. To assess the impact of the global circulation on the convective layer, we used rates from a 1-D radiative-convective model. The resolved layer, taking place between 1.0 × 105 and 3.8 × 104 Pa (48-53 km), is organized as polygonal closed cells of about 10 km wide with vertical wind of several meters per second. The convection emits gravity waves both above and below the convective layer leading to temperature perturbations of several tenths of kelvin with vertical wavelength between 1 and 3 km and horizontal wavelength from 1 to 10 km. The thickness of the convective layer and the amplitudes of waves are consistent with observations, though slightly underestimated. The global dynamics heating greatly modify the convective layer.

  4. Relation of Cloud Occurrence Frequency, Overlap, and Effective Thickness Derived from CALIPSO and CloudSat Merged Cloud Vertical Profiles

    NASA Technical Reports Server (NTRS)

    Kato, Seiji; Sun-Mack, Sunny; Miller, Walter F.; Rose, Fred G.; Chen, Yan; Minnis, Patrick; Wielicki, Bruce A.

    2009-01-01

    A cloud frequency of occurrence matrix is generated using merged cloud vertical profile derived from Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) and Cloud Profiling Radar (CPR). The matrix contains vertical profiles of cloud occurrence frequency as a function of the uppermost cloud top. It is shown that the cloud fraction and uppermost cloud top vertical pro les can be related by a set of equations when the correlation distance of cloud occurrence, which is interpreted as an effective cloud thickness, is introduced. The underlying assumption in establishing the above relation is that cloud overlap approaches the random overlap with increasing distance separating cloud layers and that the probability of deviating from the random overlap decreases exponentially with distance. One month of CALIPSO and CloudSat data support these assumptions. However, the correlation distance sometimes becomes large, which might be an indication of precipitation. The cloud correlation distance is equivalent to the de-correlation distance introduced by Hogan and Illingworth [2000] when cloud fractions of both layers in a two-cloud layer system are the same.

  5. Coordinated Parameterization Development and Large-Eddy Simulation for Marine and Arctic Cloud-Topped Boundary Layers

    NASA Technical Reports Server (NTRS)

    Bretherton, Christopher S.

    2002-01-01

    The goal of this project was to compare observations of marine and arctic boundary layers with: (1) parameterization systems used in climate and weather forecast models; and (2) two and three dimensional eddy resolving (LES) models for turbulent fluid flow. Based on this comparison, we hoped to better understand, predict, and parameterize the boundary layer structure and cloud amount, type, and thickness as functions of large scale conditions that are predicted by global climate models. The principal achievements of the project were as follows: (1) Development of a novel boundary layer parameterization for large-scale models that better represents the physical processes in marine boundary layer clouds; and (2) Comparison of column output from the ECMWF global forecast model with observations from the SHEBA experiment. Overall the forecast model did predict most of the major precipitation events and synoptic variability observed over the year of observation of the SHEBA ice camp.

  6. Cirrus cloud spectra and layers observed during the FIRE and GASP projects

    NASA Technical Reports Server (NTRS)

    Flatau, Piotr J.; Gultepe, I.; Nastrom, G.; Cotton, William R.; Heymsfield, A. J.

    1990-01-01

    A general characterization is developed for cirrus clouds in terms of their spectra, shapes, optical thicknesses, and radiative properties for use in numerical models. Data sets from the Global Atmospheric Sampling Project (GASP) of the upper troposphere and the First ISCCP Regional Experiment (FIRE) are combined and analyzed to study general traits of cirrus clouds. A definition is given for 2D turbulence, and the GASP and FIRE data sets are examined with respect to cirrus layers and entrainment and to dominant turbulent scales. The approach employs conditional sampling in cloudy and clear air, power-spectral analysis, and mixing-line-type diagrams. Evidence is given for a well mixed cloud deck and for the tendency of cirrus to be formed in multilayer structures. The results are of use in mesoscale and global circulation models which predict cirrus, in small-scale cirrus modeling, and in studying the role of gravity waves in the horizontal structure of upper tropospheric clouds.

  7. Time dependent charging of layer clouds in the global electric circuit

    NASA Astrophysics Data System (ADS)

    Zhou, Limin; Tinsley, Brian A.

    2012-09-01

    There is much observational data consistent with the hypothesis that the ionosphere-earth current density (Jz) in the global electric circuit, which is modulated by both solar activity and thunderstorm activity, affects atmospheric dynamics and cloud cover. One candidate mechanism involves Jz causing the accumulation of space charge on droplets and aerosol particles, that affects the rate of scavenging of the latter, notably those of Cloud Condensation Nuclei (CCN) and Ice Forming Nuclei (IFN) (Tinsley, 2008, 2010). Space charge is the difference, per unit volume, between total positive and total negative electrical charge that is on droplets, aerosol particles (including the CCN and IFN) and air ions. The cumulative effects of the scavenging in stratiform clouds and aerosol layers in an air mass over the lifetime of the aerosol particles of 1-10 days affects the concentration and size distribution of the CCN, so that in subsequent episodes of cloud formation (including deep convective clouds) there can be effects on droplet size distribution, coagulation, precipitation processes, and even storm dynamics.Because the time scales for charging for some clouds can be long compared to cloud lifetimes, the amount of charge at a given time, and its effect on scavenging, depend more on the charging rate than on the equilibrium charge that would eventually be attained. To evaluate this, a new time-dependent charging model has been developed. The results show that for typical altostratus clouds with typical droplet radii 10 μm and aerosol particles of radius of 0.04 μm, the time constant for charging in response to a change in Jz is about 800 s, which is comparable to cloud formation and dissipation timescales for some cloud situations. The charging timescale is found to be strong functions of altitude and aerosol concentration, with the time constant for droplet charging at 2 km in air with a high concentration of aerosols being about an hour, and for clouds at 10 km in

  8. Observations of specular reflective particles and layers in crystal clouds.

    PubMed

    Balin, Yurii S; Kaul, Bruno V; Kokhanenko, Grigorii P; Penner, Ioganes E

    2011-03-28

    In the present article, results of observations of high crystal clouds with high spatial and temporal resolution using the ground-based polarization LOSA-S lidar are described. Cases of occurrence of specularly reflective layers formed by particles oriented predominantly in the horizontal plane are demonstrated. Results of measuring echo-signal depolarization are compared for linear and circular polarization states of the initial laser beam.

  9. RACORO continental boundary layer cloud investigations. Part I: Case study development and ensemble large-scale forcings

    DOE PAGES

    Vogelmann, Andrew M.; Fridlind, Ann M.; Toto, Tami; ...

    2015-06-19

    Observation-based modeling case studies of continental boundary layer clouds have been developed to study cloudy boundary layers, aerosol influences upon them, and their representation in cloud- and global-scale models. Three 60-hour case study periods span the temporal evolution of cumulus, stratiform, and drizzling boundary layer cloud systems, representing mixed and transitional states rather than idealized or canonical cases. Based on in-situ measurements from the RACORO field campaign and remote-sensing observations, the cases are designed with a modular configuration to simplify use in large-eddy simulations (LES) and single-column models. Aircraft measurements of aerosol number size distribution are fit to lognormal functionsmore » for concise representation in models. Values of the aerosol hygroscopicity parameter, κ, are derived from observations to be ~0.10, which are lower than the 0.3 typical over continents and suggestive of a large aerosol organic fraction. Ensemble large-scale forcing datasets are derived from the ARM variational analysis, ECMWF forecasts, and a multi-scale data assimilation system. The forcings are assessed through comparison of measured bulk atmospheric and cloud properties to those computed in 'trial' large-eddy simulations, where more efficient run times are enabled through modest reductions in grid resolution and domain size compared to the full-sized LES grid. Simulations capture many of the general features observed, but the state-of-the-art forcings were limited at representing details of cloud onset, and tight gradients and high-resolution transients of importance. Methods for improving the initial conditions and forcings are discussed. The cases developed are available to the general modeling community for studying continental boundary clouds.« less

  10. RACORO Continental Boundary Layer Cloud Investigations: 3. Separation of Parameterization Biases in Single-Column Model CAM5 Simulations of Shallow Cumulus

    NASA Technical Reports Server (NTRS)

    Lin, Wuyin; Liu, Yangang; Vogelmann, Andrew M.; Fridlind, Ann; Endo, Satoshi; Song, Hua; Feng, Sha; Toto, Tami; Li, Zhijin; Zhang, Minghua

    2015-01-01

    Climatically important low-level clouds are commonly misrepresented in climate models. The FAst-physics System TEstbed and Research (FASTER) Project has constructed case studies from the Atmospheric Radiation Measurement Climate Research Facility's Southern Great Plain site during the RACORO aircraft campaign to facilitate research on model representation of boundary-layer clouds. This paper focuses on using the single-column Community Atmosphere Model version 5 (SCAM5) simulations of a multi-day continental shallow cumulus case to identify specific parameterization causes of low-cloud biases. Consistent model biases among the simulations driven by a set of alternative forcings suggest that uncertainty in the forcing plays only a relatively minor role. In-depth analysis reveals that the model's shallow cumulus convection scheme tends to significantly under-produce clouds during the times when shallow cumuli exist in the observations, while the deep convective and stratiform cloud schemes significantly over-produce low-level clouds throughout the day. The links between model biases and the underlying assumptions of the shallow cumulus scheme are further diagnosed with the aid of large-eddy simulations and aircraft measurements, and by suppressing the triggering of the deep convection scheme. It is found that the weak boundary layer turbulence simulated is directly responsible for the weak cumulus activity and the simulated boundary layer stratiform clouds. Increased vertical and temporal resolutions are shown to lead to stronger boundary layer turbulence and reduction of low-cloud biases.

  11. RACORO continental boundary layer cloud investigations. 3. Separation of parameterization biases in single-column model CAM5 simulations of shallow cumulus

    DOE PAGES

    Lin, Wuyin; Liu, Yangang; Vogelmann, Andrew M.; ...

    2015-06-19

    Climatically important low-level clouds are commonly misrepresented in climate models. The FAst-physics System TEstbed and Research (FASTER) project has constructed case studies from the Atmospheric Radiation Measurement (ARM) Climate Research Facility's Southern Great Plain site during the RACORO aircraft campaign to facilitate research on model representation of boundary-layer clouds. This paper focuses on using the single-column Community Atmosphere Model version 5 (SCAM5) simulations of a multi-day continental shallow cumulus case to identify specific parameterization causes of low-cloud biases. Consistent model biases among the simulations driven by a set of alternative forcings suggest that uncertainty in the forcing plays only amore » relatively minor role. In-depth analysis reveals that the model's shallow cumulus convection scheme tends to significantly under-produce clouds during the times when shallow cumuli exist in the observations, while the deep convective and stratiform cloud schemes significantly over-produce low-level clouds throughout the day. The links between model biases and the underlying assumptions of the shallow cumulus scheme are further diagnosed with the aid of large-eddy simulations and aircraft measurements, and by suppressing the triggering of the deep convection scheme. It is found that the weak boundary layer turbulence simulated is directly responsible for the weak cumulus activity and the simulated boundary layer stratiform clouds. Increased vertical and temporal resolutions are shown to lead to stronger boundary layer turbulence and reduction of low-cloud biases.« less

  12. MODELING NON-PRECIPITATING CUMULUS CLOUDS AS FLOW-THROUGH-REACTOR TRANSFORMER AND VENTING TRANSPORTER OF MIXED LAYER POLLUTANTS

    EPA Science Inventory

    A simple diagnostic model of cumulus convective clouds is developed and used in a sensitivity study to examine the extent to which the rate of change of mixed and cloud layer pollutant concentration is influenced by vertical transport and chemical transformation processes occurri...

  13. Arctic boundary layer properties and its influence on cloud occurrence frequency, phase and structure in autumn season

    NASA Astrophysics Data System (ADS)

    Qiu, S.; Dong, X.; Xi, B.

    2017-12-01

    In this study, autumnal boundary layer characteristics and cloud properties have been investigated using data collected at the Atmospheric Radiation Measurement North Slope of Alaska (ARM NSA) site from January 2002 to December 2008. We found that both cloud and planetary boundary layer (PBL) properties can be well distinguished by surface wind directions. When the ARM NSA site is dominated by a northerly wind during the period September- November, the PBL is at near saturation for all three months; while the maximum RH layer varies from low and thin in September, to higher and thicker in October, and then it becomes close to surface again in November. Both the ceilometer and the MPL derived cloud base heights coincide well with the RH maximum layer in the PBL for all three autumnal months. The frequencies of occurrence of mixed phase clouds in September and October are around 60-80% under a northerly wind, which are about 1.5 times higher than those during a southerly wind. Under northerly wind, the PDFs of PBL temperature and specific humidity are narrow and unimodal, with a peak probability around 0.4-0.5. Under a southerly wind, on the other hand, the PBL is both warmer and wetter than northerly wind profiles, which result in lower RH values (10-15% lower) in September and October; and the PDFs of PBL temperature and specific humidity are more evenly distributed with larger distribution range and lower PDF peak values (<0.3). In September, colder and dryer PBL is more favorable for mixed phase cloud formation, cloud occurrence frequency decreases from 90% to 60% as PBL temperature and specific humidity increase. In October, the frequency of occurrence of mixed phase clouds also decreases from 90% to 50-60% as PBL temperature increases. While in November, it increases first and then decreases with increasing PBL temperature and specific humidity. The frequency of occurrence of mixed phase clouds is linearly correlated to PBL RH values: for all three months, it

  14. Relationships among cloud occurrence frequency, overlap, and effective thickness derived from CALIPSO and CloudSat merged cloud vertical profiles

    NASA Astrophysics Data System (ADS)

    Kato, Seiji; Sun-Mack, Sunny; Miller, Walter F.; Rose, Fred G.; Chen, Yan; Minnis, Patrick; Wielicki, Bruce A.

    2010-01-01

    A cloud frequency of occurrence matrix is generated using merged cloud vertical profiles derived from the satellite-borne Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) and cloud profiling radar. The matrix contains vertical profiles of cloud occurrence frequency as a function of the uppermost cloud top. It is shown that the cloud fraction and uppermost cloud top vertical profiles can be related by a cloud overlap matrix when the correlation length of cloud occurrence, which is interpreted as an effective cloud thickness, is introduced. The underlying assumption in establishing the above relation is that cloud overlap approaches random overlap with increasing distance separating cloud layers and that the probability of deviating from random overlap decreases exponentially with distance. One month of Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) and CloudSat data (July 2006) support these assumptions, although the correlation length sometimes increases with separation distance when the cloud top height is large. The data also show that the correlation length depends on cloud top hight and the maximum occurs when the cloud top height is 8 to 10 km. The cloud correlation length is equivalent to the decorrelation distance introduced by Hogan and Illingworth (2000) when cloud fractions of both layers in a two-cloud layer system are the same. The simple relationships derived in this study can be used to estimate the top-of-atmosphere irradiance difference caused by cloud fraction, uppermost cloud top, and cloud thickness vertical profile differences.

  15. Exploring noctilucent cloud variability using the nudged and extended version of the Canadian Middle Atmosphere Model

    NASA Astrophysics Data System (ADS)

    Kuilman, Maartje; Karlsson, Bodil; Benze, Susanne; Megner, Linda

    2017-11-01

    Ice particles in the summer mesosphere - such as those connected to noctilucent clouds and polar mesospheric summer echoes - have since their discovery contributed to the uncovering of atmospheric processes on various scales ranging from interactions on molecular levels to global scale circulation patterns. While there are numerous model studies on mesospheric ice microphysics and how the clouds relate to the background atmosphere, there are at this point few studies using comprehensive global climate models to investigate observed variability and climatology of noctilucent clouds. In this study it is explored to what extent the large-scale inter-annual characteristics of noctilucent clouds are captured in a 30-year run - extending from 1979 to 2009 - of the nudged and extended version of the Canadian Middle Atmosphere Model (CMAM30). To construct and investigate zonal mean inter-seasonal variability in noctilucent cloud occurrence frequency and ice mass density in both hemispheres, a simple cloud model is applied in which it is assumed that the ice content is solely controlled by the local temperature and water vapor volume mixing ratio. The model results are compared to satellite observations, each having an instrument-specific sensitivity when it comes to detecting noctilucent clouds. It is found that the model is able to capture the onset dates of the NLC seasons in both hemispheres as well as the hemispheric differences in NLCs, such as weaker NLCs in the SH than in the NH and differences in cloud height. We conclude that the observed cloud climatology and zonal mean variability are well captured by the model.

  16. Large-eddy simulation of subtropical cloud-topped boundary layers: 1. A forcing framework with closed surface energy balance

    NASA Astrophysics Data System (ADS)

    Tan, Zhihong; Schneider, Tapio; Teixeira, João.; Pressel, Kyle G.

    2016-12-01

    Large-eddy simulation (LES) of clouds has the potential to resolve a central question in climate dynamics, namely, how subtropical marine boundary layer (MBL) clouds respond to global warming. However, large-scale processes need to be prescribed or represented parameterically in the limited-area LES domains. It is important that the representation of large-scale processes satisfies constraints such as a closed energy balance in a manner that is realizable under climate change. For example, LES with fixed sea surface temperatures usually do not close the surface energy balance, potentially leading to spurious surface fluxes and cloud responses to climate change. Here a framework of forcing LES of subtropical MBL clouds is presented that enforces a closed surface energy balance by coupling atmospheric LES to an ocean mixed layer with a sea surface temperature (SST) that depends on radiative fluxes and sensible and latent heat fluxes at the surface. A variety of subtropical MBL cloud regimes (stratocumulus, cumulus, and stratocumulus over cumulus) are simulated successfully within this framework. However, unlike in conventional frameworks with fixed SST, feedbacks between cloud cover and SST arise, which can lead to sudden transitions between cloud regimes (e.g., stratocumulus to cumulus) as forcing parameters are varied. The simulations validate this framework for studies of MBL clouds and establish its usefulness for studies of how the clouds respond to climate change.

  17. Infrared Image of Low Clouds on Venus

    NASA Technical Reports Server (NTRS)

    1993-01-01

    This false-color image is a near-infrared map of lower-level clouds on the night side of Venus, obtained by the Near Infrared Mapping Spectrometer aboard the Galileo spacecraft as it approached the planet's night side on February 10, 1990. Bright slivers of sunlit high clouds are visible above and below the dark, glowing hemisphere. The spacecraft is about 100,000 kilometers (60,000 miles) above the planet. An infrared wavelength of 2.3 microns (about three times the longest wavelength visible to the human eye) was used. The map shows the turbulent, cloudy middle atmosphere some 50-55 kilometers (30- 33 miles) above the surface, 10-16 kilometers or 6-10 miles below the visible cloudtops. The red color represents the radiant heat from the lower atmosphere (about 400 degrees Fahrenheit) shining through the sulfuric acid clouds, which appear as much as 10 times darker than the bright gaps between clouds. This cloud layer is at about -30 degrees Fahrenheit, at a pressure about 1/2 Earth's surface atmospheric pressure. Near the equator, the clouds appear fluffy and blocky; farther north, they are stretched out into East-West filaments by winds estimated at more than 150 mph, while the poles are capped by thick clouds at this altitude.

  18. Comparisons of Satellite-Deduced Overlapping Cloud Properties and CALIPSO CloudSat Data

    NASA Technical Reports Server (NTRS)

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

    2010-01-01

    Introduction to the overlapped cloud properties derived from polar-orbiting (MODIS) and geostationary (GOES-12, -13, Meteosat-8, -9, etc.) meteorological satellites, which are produced at the NASA Langley Research Center (LaRC) cloud research & development team (NASA lead scientist: Dr. Patrick Minnis). Comparison of the LaRC CERES MODIS Edition-3 overlapped cloud properties to the CALIPSO and the CloudSat active sensing data. High clouds and overlapped clouds occur frequently as deduced by CALIPSO (44 & 25%), CloudSat (25 & 4%), and MODIS (37 & 6%). Large fractions of optically-thin cirrus and overlapped clouds are deduced from CALIPSO, but much smaller fractions are from CloudSat and MODIS. For overlapped clouds, the averaged upper-layer CTHs are about 12.8 (CALIPSO), 10.9 (CloudSat) and 10 km (MODIS), and the averaged lower-layer CTHs are about 3.6 (CALIPSO), 3.2 (CloudSat) and 3.9 km (MODIS). Based on comparisons of upper and lower-layer cloud properties as deduced from the MODIS, CALIPSO and CloudSat data, more enhanced passive satellite methods for retrieving thin cirrus and overlapped cloud properties are needed and are under development.

  19. Investigation of the marine boundary layer cloud and CCN properties under coupled and decoupled conditions over the Azores

    DOE PAGES

    Dong, Xiquan; Schwantes, Adam C.; Xi, Baike; ...

    2015-06-10

    Here, six coupled and decoupled marine boundary layer (MBL) clouds were chosen from the 19 month Atmospheric Radiation Measurement Mobile Facility data set over the Azores. Thresholds of liquid water potential temperature difference Δθ L < 0.5 K (>0.5 K) and total water mixing ratio difference Δq t < 0.5 g/kg (>0.5 g/kg) below the cloud base were used for selecting the coupled (decoupled) cases. A schematic diagram was given to demonstrate the coupled and decoupled MBL vertical structures and how they associate with nondrizzle, virga, and rain drizzle events. Out of a total of 2676 5 min samples, 34.5%more » were classified as coupled and 65.5% as decoupled, 36.2% as nondrizzle and 63.8% as drizzle (47.7% as virga and 16.1% as rain), and 33.4% as daytime and 66.6% as nighttime. The decoupled cloud layer is deeper (0.406 km) than coupled cloud layer (0.304 km), and its liquid water path and cloud droplet effective radius (r e) values (122.1 gm -2 and 13.0 µm) are higher than coupled ones (83.7 gm -2 and 10.4 µm). Conversely, decoupled stratocumuli have lower cloud droplet number concentration (N d) and surface cloud condensation nucleus (CCN) concentration (N CCN) (74.5 cm -3 and 150.9 cm -3) than coupled stratocumuli (111.7 cm -3 and 216.4 cm -3). The linear regressions between r e and N d with N CCN have demonstrated that coupled r e and N d strongly depend on N CCN and have higher correlations (-0.56 and 0.59) with N CCN than decoupled results (-0.14 and 0.25). The MBL cloud properties under nondrizzle and virga drizzle conditions are similar to each other but significantly different to those of rain drizzle.« less

  20. 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

  1. Clouds, Precipitation, and Marine Boundary Layer Structure during the MAGIC Field Campaign

    DOE PAGES

    Zhou, Xiaoli; Kollias, Pavlos; Lewis, Ernie R.

    2015-03-01

    The recent ship-based MAGIC (Marine ARM GCSS Pacific Cross-Section Intercomparison (GPCI) Investigation of Clouds) field campaign with the marine-capable Second ARM Mobile Facility (AMF2) deployed on the Horizon Lines cargo container M/V Spirit provided nearly 200 days of intraseasonal high-resolution observations of clouds, precipitation, and marine boundary layer (MBL) structure on multiple legs between Los Angeles, California, and Honolulu, Hawaii. During the deployment, MBL clouds exhibited a much higher frequency of occurrence than other cloud types and occurred more often in the warm season than in the cold season. MBL clouds demonstrated a propensity to produce precipitation, which often evaporatedmore » before reaching the ocean surface. The formation of stratocumulus is strongly correlated to a shallow MBL with a strong inversion and a weak transition, while cumulus formation is associated with a much weaker inversion and stronger transition. The estimated inversion strength is shown to depend seasonally on the potential temperature at 700 hPa. The location of the commencement of systematic MBL decoupling always occurred eastward of the locations of cloud breakup, and the systematic decoupling showed a strong moisture stratification. The entrainment of the dry warm air above the inversion appears to be the dominant factor triggering the systematic decoupling, while surface latent heat flux, precipitation, and diurnal circulation did not play major roles. MBL clouds broke up over a short spatial region due to the changes in the synoptic conditions, implying that in real atmospheric conditions the MBL clouds do not have enough time to evolve as in the idealized models. (auth)« less

  2. Parameterizing Grid-Averaged Longwave Fluxes for Inhomogeneous Marine Boundary Layer Clouds

    NASA Technical Reports Server (NTRS)

    Barker, Howard W.; Wielicki, Bruce A.

    1997-01-01

    This paper examines the relative impacts on grid-averaged longwave flux transmittance (emittance) for Marine Boundary Layer (MBL) cloud fields arising from horizontal variability of optical depth tau and cloud sides, First, using fields of Landsat-inferred tau and a Monte Carlo photon transport algorithm, it is demonstrated that mean all-sky transmittances for 3D variable MBL clouds can be computed accurately by the conventional method of linearly weighting clear and cloudy transmittances by their respective sky fractions. Then, the approximations of decoupling cloud and radiative properties and assuming independent columns are shown to be adequate for computation of mean flux transmittance. Since real clouds have nonzero geometric thicknesses, cloud fractions A'(sub c) presented to isotropic beams usually exceed the more familiar vertically projected cloud fractions A(sub c). It is shown, however, that when A(sub c)less than or equal to 0.9, biases for all-sky transmittance stemming from use of A(sub c) as opposed to A'(sub c) are roughly 2-5 times smaller than, and opposite in sign to, biases due to neglect of horizontal variability of tau. By neglecting variable tau, all-sky transmittances are underestimated often by more than 0.1 for A(sub c) near 0.75 and this translates into relative errors that can exceed 40% (corresponding errors for all-sky emittance are about 20% for most values of A(sub c). Thus, priority should be given to development of General Circulation Model (GCM) parameterizations that account for the effects of horizontal variations in unresolved tau, effects of cloud sides are of secondary importance. On this note, an efficient stochastic model for computing grid-averaged cloudy-sky flux transmittances is furnished that assumes that distributions of tau, for regions comparable in size to GCM grid cells, can be described adequately by gamma distribution functions. While the plane-parallel, homogeneous model underestimates cloud transmittance by

  3. Simulations of Variability and Waves at Cloud Altitudes Using a Venus Middle Atmosphere General Circulation Model

    NASA Astrophysics Data System (ADS)

    Parish, H. F.; Mitchell, J.

    2017-12-01

    We have developed a Venus general circulation model, the Venus Middle atmosphere Model (VMM), to simulate the atmosphere from just below the cloud deck 40 km altitude to around 100 km altitude. Our primary goal is to assess the influence of waves on the variability of winds and temperatures observed around Venus' cloud deck. Venus' deep atmosphere is not simulated directly in the VMM model, so the effects of waves propagating upwards from the lower atmosphere is represented by forcing at the lower boundary of the model. Sensitivity tests allow appropriate amplitudes for the wave forcing to be determined by comparison with Venus Express and probe measurements and allow the influence of waves on the cloud-level atmosphere to be investigated. Observations at cloud altitudes are characterized by waves with a wide variety of periods and wavelengths, including gravity waves, thermal tides, Rossby waves, and Kelvin waves. These waves may be generated within the cloud deck by instabilities, or may propagate up from the deep atmosphere. Our development of the VMM is motivated by the fact that the circulation and dynamics between the surface and the cloud levels are not well measured and wind velocities below 40 km altitude cannot be observed remotely, so we focus on the dynamics at cloud levels and above. Initial results from the VMM with a simplified radiation scheme have been validated by comparison with Pioneer Venus and Venus Express observations and show reasonable agreement with the measurements.

  4. Low Cloud Feedback to Surface Warming in the World's First Global Climate Model with Explicit Embedded Boundary Layer Turbulence

    NASA Astrophysics Data System (ADS)

    Parishani, H.; Pritchard, M. S.; Bretherton, C. S.; Wyant, M. C.; Khairoutdinov, M.; Singh, B.

    2017-12-01

    Biases and parameterization formulation uncertainties in the representation of boundary layer clouds remain a leading source of possible systematic error in climate projections. Here we show the first results of cloud feedback to +4K SST warming in a new experimental climate model, the ``Ultra-Parameterized (UP)'' Community Atmosphere Model, UPCAM. We have developed UPCAM as an unusually high-resolution implementation of cloud superparameterization (SP) in which a global set of cloud resolving arrays is embedded in a host global climate model. In UP, the cloud-resolving scale includes sufficient internal resolution to explicitly generate the turbulent eddies that form marine stratocumulus and trade cumulus clouds. This is computationally costly but complements other available approaches for studying low clouds and their climate interaction, by avoiding parameterization of the relevant scales. In a recent publication we have shown that UP, while not without its own complexity trade-offs, can produce encouraging improvements in low cloud climatology in multi-month simulations of the present climate and is a promising target for exascale computing (Parishani et al. 2017). Here we show results of its low cloud feedback to warming in multi-year simulations for the first time. References: Parishani, H., M. S. Pritchard, C. S. Bretherton, M. C. Wyant, and M. Khairoutdinov (2017), Toward low-cloud-permitting cloud superparameterization with explicit boundary layer turbulence, J. Adv. Model. Earth Syst., 9, doi:10.1002/2017MS000968.

  5. New insights about cloud vertical structure from CloudSat and CALIPSO observations

    NASA Astrophysics Data System (ADS)

    Oreopoulos, Lazaros; Cho, Nayeong; Lee, Dongmin

    2017-09-01

    Active cloud observations from A-Train's CloudSat and CALIPSO satellites offer new opportunities to examine the vertical structure of hydrometeor layers. We use the 2B-CLDCLASS-LIDAR merged CloudSat-CALIPSO product to examine global aspects of hydrometeor vertical stratification. We group the data into major cloud vertical structure (CVS) classes based on our interpretation of how clouds in three standard atmospheric layers overlap and provide their global frequency of occurrence. The two most frequent CVS classes are single-layer (per our definition) low and high clouds that represent 53% of cloudy skies, followed by high clouds overlying low clouds, and vertically extensive clouds that occupy near-contiguously a large portion of the troposphere. The prevalence of these configurations changes seasonally and geographically, between daytime and nighttime, and between continents and oceans. The radiative effects of the CVS classes reveal the major radiative warmers and coolers from the perspective of the planet as a whole, the surface, and the atmosphere. Single-layer low clouds dominate planetary and atmospheric cooling and thermal infrared surface warming. We also investigate the consistency between passive and active views of clouds by providing the CVS breakdowns of Moderate Resolution Imaging Spectroradiometer cloud regimes for spatiotemporally coincident MODIS-Aqua (also on the A-Train) and CloudSat-CALIPSO daytime observations. When the analysis is expanded for a more in-depth look at the most heterogeneous of the MODIS cloud regimes, it ultimately confirms previous interpretations of their makeup that did not have the benefit of collocated active observations.

  6. Comparison of Cirrus Cloud Models: A Project of the GEWEX Cloud System Study (GCSS) Working Group on Cirrus Cloud Systems

    NASA Technical Reports Server (NTRS)

    Starr, David OC.; Benedetti, Angela; Boehm, Matt; Brown, Philip R. A.; Gierens, Klaus M.; Girard, Eric; Giraud, Vincent; Jakob, Christian; Jensen, Eric; Khvorostyanov, Vitaly; hide

    2000-01-01

    The GEWEX Cloud System Study (GCSS, GEWEX is the Global Energy and Water Cycle Experiment) is a community activity aiming to promote development of improved cloud parameterizations for application in the large-scale general circulation models (GCMs) used for climate research and for numerical weather prediction (Browning et al, 1994). The GCSS strategy is founded upon the use of cloud-system models (CSMs). These are "process" models with sufficient spatial and temporal resolution to represent individual cloud elements, but spanning a wide range of space and time scales to enable statistical analysis of simulated cloud systems. GCSS also employs single-column versions of the parametric cloud models (SCMs) used in GCMs. GCSS has working groups on boundary-layer clouds, cirrus clouds, extratropical layer cloud systems, precipitating deep convective cloud systems, and polar clouds.

  7. Comparison of Cirrus Cloud Models: A Project of the GEWEX Cloud System Study (GCSS) Working Group on Cirrus Cloud Systems

    NASA Technical Reports Server (NTRS)

    Starr, David O'C.; Benedetti, Angela; Boehm, Matt; Brown, Philip R. A.; Gierens, Klaus M.; Girard, Eric; Giraud, Vincent; Jakob, Christian; Jensen, Eric

    2000-01-01

    The GEWEX Cloud System Study (GCSS, GEWEX is the Global Energy and Water Cycle Experiment) is a community activity aiming to promote development of improved cloud parameterizations for application in the large-scale general circulation models (GCMs) used for climate research and for numerical weather prediction. The GCSS strategy is founded upon the use of cloud-system models (CSMs). These are "process" models with sufficient spatial and temporal resolution to represent individual cloud elements, but spanning a wide range of space and time scales to enable statistical analysis of simulated cloud systems. GCSS also employs single-column versions of the parametric cloud models (SCMs) used in GCMs. GCSS has working groups on boundary-layer clouds, cirrus clouds, extratropical layer cloud systems, precipitating deep convective cloud systems, and polar clouds.

  8. Assessment of marine boundary layer cloud simulations in the CAM with CLUBB and updated microphysics scheme based on ARM observations from the Azores

    SciTech Connect

    Zheng, Xue; Klein, S. A.; Ma, H. -Y.

    To assess marine boundary layer (MBL) cloud simulations in three versions of the Community Atmosphere Model (CAM), three sets of short-term global hindcasts are performed and compared to Atmospheric Radiation Measurement Program (ARM) observations on Graciosa Island in the Azores from June 2009 to December 2010. Here, the three versions consist of CAM5.3 with default schemes (CAM5.3), CAM5.3 with Cloud Layers Unified By Binormals (CLUBB-MG1), and CAM5.3 with CLUBB and updated microphysics scheme (CLUBB-MG2). Our results show that relative to CAM5.3 default schemes, simulations with CLUBB better represent MBL cloud base height, the height of the major cloud layer, andmore » the daily cloud cover variability. CLUBB also better simulates the relationship of cloud fraction to cloud liquid water path (LWP) most likely due to CLUBB's consistent treatment of these variables through a probability distribution function (PDF) approach. Subcloud evaporation of precipitation is substantially enhanced in simulations with CLUBB-MG2 and is more realistic based on the limited observational estimate. Despite these improvements, all model versions underestimate MBL cloud cover. CLUBB-MG2 reduces biases in in-cloud LWP (clouds are not too bright) but there are still too few of MBL clouds due to an underestimate in the frequency of overcast scenes. Thus, combining CLUBB with MG2 scheme better simulates MBL cloud processes, but because biases remain in MBL cloud cover CLUBB-MG2 does not improve the simulation of the surface shortwave cloud radiative effect (CRE SW).« less

  9. Assessment of marine boundary layer cloud simulations in the CAM with CLUBB and updated microphysics scheme based on ARM observations from the Azores

    DOE PAGES

    Zheng, Xue; Klein, S. A.; Ma, H. -Y.; ...

    2016-07-19

    To assess marine boundary layer (MBL) cloud simulations in three versions of the Community Atmosphere Model (CAM), three sets of short-term global hindcasts are performed and compared to Atmospheric Radiation Measurement Program (ARM) observations on Graciosa Island in the Azores from June 2009 to December 2010. Here, the three versions consist of CAM5.3 with default schemes (CAM5.3), CAM5.3 with Cloud Layers Unified By Binormals (CLUBB-MG1), and CAM5.3 with CLUBB and updated microphysics scheme (CLUBB-MG2). Our results show that relative to CAM5.3 default schemes, simulations with CLUBB better represent MBL cloud base height, the height of the major cloud layer, andmore » the daily cloud cover variability. CLUBB also better simulates the relationship of cloud fraction to cloud liquid water path (LWP) most likely due to CLUBB's consistent treatment of these variables through a probability distribution function (PDF) approach. Subcloud evaporation of precipitation is substantially enhanced in simulations with CLUBB-MG2 and is more realistic based on the limited observational estimate. Despite these improvements, all model versions underestimate MBL cloud cover. CLUBB-MG2 reduces biases in in-cloud LWP (clouds are not too bright) but there are still too few of MBL clouds due to an underestimate in the frequency of overcast scenes. Thus, combining CLUBB with MG2 scheme better simulates MBL cloud processes, but because biases remain in MBL cloud cover CLUBB-MG2 does not improve the simulation of the surface shortwave cloud radiative effect (CRE SW).« less

  10. Clouds, Aerosol, and Precipitation in the Marine Boundary Layer (CAP-MBL) Final Campaign Report

    SciTech Connect

    Wood, R.

    2016-01-01

    The extensive coverage of low clouds over the subtropical eastern oceans greatly impacts the current climate. In addition, the response of low clouds to changes in atmospheric greenhouse gases and aerosols is a major source of uncertainty, which thwarts accurate prediction of future climate change. Low clouds are poorly simulated in climate models, partly due to inadequate long-term simultaneous observations of their macrophysical and microphysical structure, radiative effects, and associated aerosol distribution in regions where their impact is greatest. The thickness and extent of subtropical low clouds is dependent on tight couplings between surface fluxes of heat and moisture, radiativemore » cooling, boundary layer turbulence, and precipitation (much of which evaporates before reaching the ocean surface and is closely connected to the abundance of cloud condensation nuclei). These couplings have been documented as a result of past field programs and model studies. However, extensive research is still required to achieve a quantitative understanding sufficient for developing parameterizations, which adequately predict aerosol indirect effects and low cloud response to climate perturbations. This is especially true of the interactions between clouds, aerosol, and precipitation. These processes take place in an ever-changing synoptic environment that can confound interpretation of short time period observations.« less

  11. Characteristics of cirrus clouds and tropical tropopause layer: Seasonal variation and long-term trends

    NASA Astrophysics Data System (ADS)

    Pandit, Amit Kumar; Gadhavi, Harish; Ratnam, M. Venkat; Jayaraman, A.; Raghunath, K.; Rao, S. Vijaya Bhaskara

    2014-12-01

    In the present study, characteristics of tropical cirrus clouds observed during 1998-2013 using a ground-based lidar located at Gadanki (13.5°N, 79.2°E), India, are presented. Altitude occurrences of cirrus clouds as well as its top and base heights are estimated using the advanced mathematical tool, wavelet covariance transform (WCT). The association of observed cirrus cloud properties with the characteristics of tropical tropopause layer (TTL) is investigated using co-located radiosonde measurements available since 2006. In general, cirrus clouds occurred for about 44% of the total lidar observation time (6246 h). The most probable altitude at which cirrus clouds occurr is 14.5 km. The occurrence of cirrus clouds exhibited a strong seasonal dependence with maximum occurrence during monsoon season (76%) and minimum occurrence during winter season (33%) which is consistent with the results reported recently using space-based lidar measurements. Most of the time, cirrus top was located within the TTL (between cold point and convective outflow level) while cirrus base occurred near the convective outflow level. The geometrical thickness of the cirrus cloud is found to be higher during monsoon season compared to winter and there exists a weak inverse relation with TTL thickness. During the observation period the percentage occurrence of cirrus clouds near the tropopause showed an 8.4% increase at 70% confidence level. In the last 16 years, top and base heights of cirrus cloud increased by 0.56 km and 0.41 km, respectively.

  12. Cloud vertical profiles derived from CALIPSO and CloudSat and a comparison with MODIS derived clouds

    NASA Astrophysics Data System (ADS)

    Kato, S.; Sun-Mack, S.; Miller, W. F.; Rose, F. G.; Minnis, P.; Wielicki, B. A.; Winker, D. M.; Stephens, G. L.; Charlock, T. P.; Collins, W. D.; Loeb, N. G.; Stackhouse, P. W.; Xu, K.

    2008-05-01

    CALIPSO and CloudSat from the a-train provide detailed information of vertical distribution of clouds and aerosols. The vertical distribution of cloud occurrence is derived from one month of CALIPSO and CloudSat data as a part of the effort of merging CALIPSO, CloudSat and MODIS with CERES data. This newly derived cloud profile is compared with the distribution of cloud top height derived from MODIS on Aqua from cloud algorithms used in the CERES project. The cloud base from MODIS is also estimated using an empirical formula based on the cloud top height and optical thickness, which is used in CERES processes. While MODIS detects mid and low level clouds over the Arctic in April fairly well when they are the topmost cloud layer, it underestimates high- level clouds. In addition, because the CERES-MODIS cloud algorithm is not able to detect multi-layer clouds and the empirical formula significantly underestimates the depth of high clouds, the occurrence of mid and low-level clouds is underestimated. This comparison does not consider sensitivity difference to thin clouds but we will impose an optical thickness threshold to CALIPSO derived clouds for a further comparison. The effect of such differences in the cloud profile to flux computations will also be discussed. In addition, the effect of cloud cover to the top-of-atmosphere flux over the Arctic using CERES SSF and FLASHFLUX products will be discussed.

  13. Remote sounding of cloudy atmospheres. I - The single cloud layer

    NASA Technical Reports Server (NTRS)

    Chahine, M. T.

    1974-01-01

    The relaxation method for the inverse solution of the radiative transfer equation is applied in a dual-frequency scheme for the determination of complete vertical temperature profiles in cloudy atmospheres from radiance observations alone, without any additional information related to the expected solutions. The dual-frequency principle employs to advantage a property in the Planck function of the dependence of intensity on frequency. This property leads to the formulation of a new convergence criterion for the selection of cloud-sounding frequencies to be used for reconstructing the clear column radiance from observations made in the presence of a broken cloud layer in all fields of view. The principle is applied to the case of observations in two adjacent or partially overlapping fields of view and to the case of observations in a single field of view. The solutions are illustrated by numerical examples in the dual-frequency ranges of the 4.3 and 15-micron CO2 bands of the terrestrial atmosphere.

  14. Cloud condensation nuclei near marine cumulus

    NASA Technical Reports Server (NTRS)

    Hudson, James G.

    1993-01-01

    Extensive airborne measurements of cloud condensation nucleus (CCN) spectra and condensation nuclei below, in, between, and above the cumulus clouds near Hawaii point to important aerosol-cloud interactions. Consistent particle concentrations of 200/cu cm were found above the marine boundary layer and within the noncloudy marine boundary layer. Lower and more variable CCN concentrations within the cloudy boundary layer, especially very close to the clouds, appear to be a result of cloud scavenging processes. Gravitational coagulation of cloud droplets may be the principal cause of this difference in the vertical distribution of CCN. The results suggest a reservoir of CCN in the free troposphere which can act as a source for the marine boundary layer.

  15. Preliminary results of fluid dynamic model calculation of convective motion induced by solar heating at the Venus cloud top level.

    NASA Astrophysics Data System (ADS)

    Lee, Yeon Joo; Imamura, Takeshi; Maejima, Yasumitsu; Sugiyama, Ko-ichiro

    The thick cloud layer of Venus reflects solar radiation effectively, resulting in a Bond albedo of 76% (Moroz et al., 1985). Most of the incoming solar flux is absorbed in the upper cloud layer at 60-70 km altitude. An unknown UV absorber is a major sink of the solar energy at the cloud top level. It produces about 40-60% of the total solar heating near the cloud tops, depending on its vertical structure (Crisp et al., 1986; Lee et al., in preparation). UV images of Venus show a clear difference in morphology between laminar flow shaped clouds on the morning side and convective-like cells on the afternoon side of the planet in the equatorial region (Titov et al., 2012). This difference is probably related to strong solar heating at the cloud tops at the sub-solar point, rather than the influence from deeper level convection in the low and middle cloud layers (Imamura et al., 2014). Also, small difference in cloud top structures may trigger horizontal convection at this altitude, because various cloud top structures can significantly alter the solar heating and thermal cooling rates at the cloud tops (Lee et al., in preparation). Performing radiative forcing calculations for various cloud top structures using a radiative transfer model (SHDOM), we investigate the effect of solar heating at the cloud tops on atmospheric dynamics. We use CReSS (Cloud Resolving Storm Simulator), and consider the altitude range from 35 km to 90 km, covering a full cloud deck.

  16. Cloud Computing Fundamentals

    NASA Astrophysics Data System (ADS)

    Furht, Borko

    In the introductory chapter we define the concept of cloud computing and cloud services, and we introduce layers and types of cloud computing. We discuss the differences between cloud computing and cloud services. New technologies that enabled cloud computing are presented next. We also discuss cloud computing features, standards, and security issues. We introduce the key cloud computing platforms, their vendors, and their offerings. We discuss cloud computing challenges and the future of cloud computing.

  17. The tropical precipitation pickup threshold and clouds in a radiative convective equilibrium model: 2. Two-layer moisture

    NASA Astrophysics Data System (ADS)

    Igel, Matthew R.

    2017-06-01

    This paper complements Part 1 in which cloud processes of aggregated convection are examined in a large-domain radiative convective equilibrium simulation in order to uncover those responsible for a consistently observed, abrupt increase in mean precipitation at a column relative humidity value of approximately 77%. In Part 2, the focus is on how the transition is affected independently by total moisture above and below the base of the melting layer. When mean precipitation rates are examined as simultaneous functions of these two moisture layers, four distinct behaviors are observed. These four behaviors suggest unique, yet familiar, physical regimes in which (i) little rain is produced by infrequent clouds, (ii) shallow convection produces increasing warm rain with increasing low-level moisture, (iii) deep convection produces progressively heavier rain above the transition point with increasing total moisture, and (iv) deep stratiform cloud produces increasingly intense precipitation from melting for increasing upper level moisture. The independent thresholds separating regimes in upper and lower layer humidity are shown to result in the value of total column humidity at which a transition between clear air and deep convection, and therefore a pickup in precipitation, is possible. All four regimes force atmospheric columns toward the pickup value at 77% column humidity, but each does so through a unique set of physical processes. Layer moisture and microphysical budgets are analyzed and contrasted with column budgets.

  18. Bipolar H II regions produced by cloud-cloud collisions

    NASA Astrophysics Data System (ADS)

    Whitworth, Anthony; Lomax, Oliver; Balfour, Scott; Mège, Pierre; Zavagno, Annie; Deharveng, Lise

    2018-05-01

    We suggest that bipolar H II regions may be the aftermath of collisions between clouds. Such a collision will produce a shock-compressed layer, and a star cluster can then condense out of the dense gas near the center of the layer. If the clouds are sufficiently massive, the star cluster is likely to contain at least one massive star, which emits ionizing radiation, and excites an H II region, which then expands, sweeping up the surrounding neutral gas. Once most of the matter in the clouds has accreted onto the layer, expansion of the H II region meets little resistance in directions perpendicular to the midplane of the layer, and so it expands rapidly to produce two lobes of ionized gas, one on each side of the layer. Conversely, in directions parallel to the midplane of the layer, expansion of the H II region stalls due to the ram pressure of the gas that continues to fall towards the star cluster from the outer parts of the layer; a ring of dense neutral gas builds up around the waist of the bipolar H II region, and may spawn a second generation of star formation. We present a dimensionless model for the flow of ionized gas in a bipolar H II region created according to the above scenario, and predict the characteristics of the resulting free-free continuum and recombination-line emission. This dimensionless model can be scaled to the physical parameters of any particular system. Our intention is that these predictions will be useful in testing the scenario outlined above, and thereby providing indirect support for the role of cloud-cloud collisions in triggering star formation.

  19. Global and regional modeling of clouds and aerosols in the marine boundary layer during VOCALS: the VOCA intercomparison

    DOE PAGES

    Wyant, M. C.; Bretherton, Christopher S.; Wood, Robert; ...

    2015-01-09

    A diverse collection of models are used to simulate the marine boundary layer in the southeast Pacific region during the period of the October–November 2008 VOCALS REx (VAMOS Ocean Cloud Atmosphere Land Study Regional Experiment) field campaign. Regional models simulate the period continuously in boundary-forced free-running mode, while global forecast models and GCMs (general circulation models) are run in forecast mode. The models are compared to extensive observations along a line at 20° S extending westward from the South American coast. Most of the models simulate cloud and aerosol characteristics and gradients across the region that are recognizably similar tomore » observations, despite the complex interaction of processes involved in the problem, many of which are parameterized or poorly resolved. Some models simulate the regional low cloud cover well, though many models underestimate MBL (marine boundary layer) depth near the coast. Most models qualitatively simulate the observed offshore gradients of SO 2, sulfate aerosol, CCN (cloud condensation nuclei) concentration in the MBL as well as differences in concentration between the MBL and the free troposphere. Most models also qualitatively capture the decrease in cloud droplet number away from the coast. However, there are large quantitative intermodel differences in both means and gradients of these quantities. Many models are able to represent episodic offshore increases in cloud droplet number and aerosol concentrations associated with periods of offshore flow. Most models underestimate CCN (at 0.1% supersaturation) in the MBL and free troposphere. The GCMs also have difficulty simulating coastal gradients in CCN and cloud droplet number concentration near the coast. The overall performance of the models demonstrates their potential utility in simulating aerosol–cloud interactions in the MBL, though quantitative estimation of aerosol–cloud interactions and aerosol indirect effects of MBL

  20. A first summary of the Layered Atlantic Smoke Interactions with Clouds (LASIC) campaign in the remote southeast Atlantic

    NASA Astrophysics Data System (ADS)

    Zuidema, P.; Adebiyi, A. A.; Aiken, A. C.; Blanchard, Y.; Castro, V.; Chiu, C.; Cunha, B.; Delgadillo, R.; Flynn, C. J.; Hardin, J. C.; Isom, B. M.; Muradyan, P.; Nitschke, K. L.; Ramajiguru, L.; Ryczek, M. R.; Sedlacek, A. J., III; Springston, S. R.; Viagas, J.; Uin, J.; Zhang, J.

    2017-12-01

    From June 1, 2016 through October 31, 2017, a DOE ARM Mobile Facility characterized the aerosol and cloud structure during two biomass-burning aerosol seasons to unprecedented detail over Ascension Island (14W, 8S), in the remote southeast Atlantic. The site is subject to the outflow of biomass-burning aerosol from continental Africa, over 1500 km away, from approximately July to November and is located within warm ocean waters that encourage deep boundary layers. Early findings indicate that smoke reaches the surface more often than not, at times reaching black carbon mass concentrations similar to those near fire sources on land, alternating occasionally with very clean surface conditions. The surface aerosol loading is not necessarily well-correlated with that in the free-troposphere, indicating distinct aerosol transport pathways. Aerosol layering is apparent in micropulse lidar data, with free-tropospheric aerosol, when present, typically in contact with the uppermost cloud layer. First estimates of the single-scattering-albedo, of approximately 0.85, appear to be remarkably consistent with estimates from airborne campaigns made elsewhere in the southeast Atlantic. The boundary layer is deeper when smoke is present near the surface and more well-mixed, with a stronger diurnal cycle in potential temperature indicating shortwave absorption. Cloudiness near the trade-wind inversion increases when smoke is present, while cloudiness changes at the lifting condensation level may reflect coincident meteorological changes. In summary the new observations indicate an aerosol-cloud regime that is extensive and with the potential to demonstrate unanticipated aerosol-cloud interactions.

  1. Satellite retrieval of cloud condensation nuclei concentrations by using clouds as CCN chambers

    PubMed Central

    Rosenfeld, Daniel; Zheng, Youtong; Hashimshoni, Eyal; Pöhlker, Mira L.; Jefferson, Anne; Pöhlker, Christopher; Yu, Xing; Zhu, Yannian; Liu, Guihua; Yue, Zhiguo; Fischman, Baruch; Li, Zhanqing; Giguzin, David; Goren, Tom; Artaxo, Paulo; Pöschl, Ulrich

    2016-01-01

    Quantifying the aerosol/cloud-mediated radiative effect at a global scale requires simultaneous satellite retrievals of cloud condensation nuclei (CCN) concentrations and cloud base updraft velocities (Wb). Hitherto, the inability to do so has been a major cause of high uncertainty regarding anthropogenic aerosol/cloud-mediated radiative forcing. This can be addressed by the emerging capability of estimating CCN and Wb of boundary layer convective clouds from an operational polar orbiting weather satellite. Our methodology uses such clouds as an effective analog for CCN chambers. The cloud base supersaturation (S) is determined by Wb and the satellite-retrieved cloud base drop concentrations (Ndb), which is the same as CCN(S). Validation against ground-based CCN instruments at Oklahoma, at Manaus, and onboard a ship in the northeast Pacific showed a retrieval accuracy of ±25% to ±30% for individual satellite overpasses. The methodology is presently limited to boundary layer not raining convective clouds of at least 1 km depth that are not obscured by upper layer clouds, including semitransparent cirrus. The limitation for small solar backscattering angles of <25° restricts the satellite coverage to ∼25% of the world area in a single day. PMID:26944081

  2. Satellite retrieval of cloud condensation nuclei concentrations by using clouds as CCN chambers.

    PubMed

    Rosenfeld, Daniel; Zheng, Youtong; Hashimshoni, Eyal; Pöhlker, Mira L; Jefferson, Anne; Pöhlker, Christopher; Yu, Xing; Zhu, Yannian; Liu, Guihua; Yue, Zhiguo; Fischman, Baruch; Li, Zhanqing; Giguzin, David; Goren, Tom; Artaxo, Paulo; Barbosa, Henrique M J; Pöschl, Ulrich; Andreae, Meinrat O

    2016-05-24

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

  3. Chemical analysis of aerosol in the Venusian cloud layer by reaction gas chromatography on board the Vega landers

    NASA Technical Reports Server (NTRS)

    Gelman, B. G.; Drozdov, Y. V.; Melnikov, V. V.; Rotin, V. A.; Khokhlov, V. N.; Bondarev, V. B.; Dolnikov, G. G.; Dyachkov, A. V.; Nenarokov, D. F.; Mukhin, L. M.

    1986-01-01

    The experiment on sulfuric acid aerosol determination in the Venusian cloud layer on board the Vega landers is described. An average content of sulfuric acid of approximately 1 mg/cu m was found for the samples taken from the atmosphere at heights from 63 to 48 km and analyzed with the SIGMA-3 chromatograph. Sulfur dioxide (SO2) was revealed in the gaseous sample at the height of 48 km. From the experimental results and blank run measurements, a suggestion is made that the Venusian cloud layer aerosol consists of more complicated particles than the sulfuric acid water solution does.

  4. Simulation of Boundary-Layer Cumulus and Stratocumulus Clouds using a Cloud-Resolving Model With Low- and Third-Order Turbulence Closures

    NASA Technical Reports Server (NTRS)

    Xu, Kuan-Man; Cheng, Anning

    2007-01-01

    The effects of subgrid-scale condensation and transport become more important as the grid spacings increase from those typically used in large-eddy simulation (LES) to those typically used in cloud-resolving models (CRMs). Incorporation of these effects can be achieved by a joint probability density function approach that utilizes higher-order moments of thermodynamic and dynamic variables. This study examines how well shallow cumulus and stratocumulus clouds are simulated by two versions of a CRM that is implemented with low-order and third-order turbulence closures (LOC and TOC) when a typical CRM horizontal resolution is used and what roles the subgrid-scale and resolved-scale processes play as the horizontal grid spacing of the CRM becomes finer. Cumulus clouds were mostly produced through subgrid-scale transport processes while stratocumulus clouds were produced through both subgrid-scale and resolved-scale processes in the TOC version of the CRM when a typical CRM grid spacing is used. The LOC version of the CRM relied upon resolved-scale circulations to produce both cumulus and stratocumulus clouds, due to small subgrid-scale transports. The mean profiles of thermodynamic variables, cloud fraction and liquid water content exhibit significant differences between the two versions of the CRM, with the TOC results agreeing better with the LES than the LOC results. The characteristics, temporal evolution and mean profiles of shallow cumulus and stratocumulus clouds are weakly dependent upon the horizontal grid spacing used in the TOC CRM. However, the ratio of the subgrid-scale to resolved-scale fluxes becomes smaller as the horizontal grid spacing decreases. The subcloud-layer fluxes are mostly due to the resolved scales when a grid spacing less than or equal to 1 km is used. The overall results of the TOC simulations suggest that a 1-km grid spacing is a good choice for CRM simulation of shallow cumulus and stratocumulus.

  5. Cloud-Resolving Model Simulations of Aerosol-Cloud Interactions Triggered by Strong Aerosol Emissions in the Arctic

    NASA Astrophysics Data System (ADS)

    Wang, H.; Kravitz, B.; Rasch, P. J.; Morrison, H.; Solomon, A.

    2014-12-01

    Previous process-oriented modeling studies have highlighted the dependence of effectiveness of cloud brightening by aerosols on cloud regimes in warm marine boundary layer. Cloud microphysical processes in clouds that contain ice, and hence the mechanisms that drive aerosol-cloud interactions, are more complicated than in warm clouds. Interactions between ice particles and liquid drops add additional levels of complexity to aerosol effects. A cloud-resolving model is used to study aerosol-cloud interactions in the Arctic triggered by strong aerosol emissions, through either geoengineering injection or concentrated sources such as shipping and fires. An updated cloud microphysical scheme with prognostic aerosol and cloud particle numbers is employed. Model simulations are performed in pure super-cooled liquid and mixed-phase clouds, separately, with or without an injection of aerosols into either a clean or a more polluted Arctic boundary layer. Vertical mixing and cloud scavenging of particles injected from the surface is still quite efficient in the less turbulent cold environment. Overall, the injection of aerosols into the Arctic boundary layer can delay the collapse of the boundary layer and increase low-cloud albedo. The pure liquid clouds are more susceptible to the increase in aerosol number concentration than the mixed-phase clouds. Rain production processes are more effectively suppressed by aerosol injection, whereas ice precipitation (snow) is affected less; thus the effectiveness of brightening mixed-phase clouds is lower than for liquid-only clouds. Aerosol injection into a clean boundary layer results in a greater cloud albedo increase than injection into a polluted one, consistent with current knowledge about aerosol-cloud interactions. Unlike previous studies investigating warm clouds, the impact of dynamical feedback due to precipitation changes is small. According to these results, which are dependent upon the representation of ice nucleation

  6. Dust in brown dwarfs and extra-solar planets. I. Chemical composition and spectral appearance of quasi-static cloud layers

    NASA Astrophysics Data System (ADS)

    Helling, Ch.; Woitke, P.; Thi, W.-F.

    2008-07-01

    Aims: Brown dwarfs are covered by dust cloud layers which cause inhomogeneous surface features and move below the observable τ = 1 level during the object's evolution. The cloud layers have a strong influence on the structure and spectral appearance of brown dwarfs and extra-solar planets, e.g. by providing high local opacities and by removing condensable elements from the atmosphere causing a sub-solar metalicity in the atmosphere. We aim at understanding the formation of cloud layers in quasi-static substellar atmospheres that consist of dirty grains composed of numerous small islands of different solid condensates. Methods: The time-dependent description is a kinetic model describing nucleation, growth and evaporation. It is extended to treat gravitational settling and is applied to the static-stationary case of substellar model atmospheres. From the solution of the dust moments, we determine the grain size distribution function approximately which, together with the calculated material volume fractions, provides the basis for applying effective medium theory and Mie theory to calculate the opacities of the composite dust grains. Results: The cloud particles in brown dwarfs and hot giant-gas planets are found to be small in the high atmospheric layers (a ≈ 0.01 μm), and are composed of a rich mixture of all considered condensates, in particular MgSiO3[s], Mg2SiO4[s] and SiO2[s]. As the particles settle downward, they increase in size and reach several 100 μm in the deepest layers. The more volatile parts of the grains evaporate and the particles stepwise purify to form composite particles of high-temperature condensates in the deeper layers, mainly made of Fe[s] and Al2O3[s]. The gas phase abundances of the elements involved in the dust formation process vary by orders of magnitudes throughout the atmosphere. The grain size distribution is found to be relatively broad in the upper atmospheric layers but strongly peaked in the deeper layers. This reflects

  7. Climatic Implications of the Observed Temperature Dependence of the Liquid Water Path of Low Clouds

    NASA Technical Reports Server (NTRS)

    DelGenio, Anthony

    1999-01-01

    The uncertainty in the global climate sensitivity to an equilibrium doubling of carbon dioxide is often stated to be 1.5-4.5 K, largely due to uncertainties in cloud feedbacks. The lower end of this range is based on the assumption or prediction in some GCMs that cloud liquid water behaves adiabatically, thus implying that cloud optical thickness will increase in a warming climate if the physical thickness of clouds is invariant. Satellite observations of low-level cloud optical thickness and liquid water path have challenged this assumption, however, at low and middle latitudes. We attempt to explain the satellite results using four years of surface remote sensing data from the Atmospheric Radiation Measurements (ARM) Cloud And Radiation Testbed (CART) site in the Southern Great Plains. We find that low cloud liquid water path is insensitive to temperature in winter but strongly decreases with temperature in summer. The latter occurs because surface relative humidity decreases with warming, causing cloud base to rise and clouds to geometrically thin. Meanwhile, inferred liquid water contents hardly vary with temperature, suggesting entrainment depletion. Physically, the temperature dependence appears to represent a transition from higher probabilities of stratified boundary layers at cold temperatures to a higher incidence of convective boundary layers at warm temperatures. The combination of our results and the earlier satellite findings imply that the minimum climate sensitivity should be revised upward from 1.5 K.

  8. Satellite retrieval of cloud condensation nuclei concentrations by using clouds as CCN chambers

    SciTech Connect

    Rosenfeld, Daniel; Zheng, Youtong; Hashimshoni, Eyal

    Quantifying the aerosol/cloud-mediated radiative effect at a global scale requires simultaneous satellite retrievals of cloud condensation nuclei (CCN) concentrations and cloud base updraft velocities ( Wb). Hitherto, the inability to do so has been a major cause of high uncertainty regarding anthropogenic aerosol/cloud-mediated radiative forcing. This can be addressed by the emerging capability of estimating CCN and Wb of boundary layer convective clouds from an operational polar orbiting weather satellite. In this paper, our methodology uses such clouds as an effective analog for CCN chambers. The cloud base supersaturation ( S) is determined by Wb and the satellite-retrieved cloud basemore » drop concentrations ( Ndb), which is the same as CCN(S). Validation against ground-based CCN instruments at Oklahoma, at Manaus, and onboard a ship in the northeast Pacific showed a retrieval accuracy of ±25% to ±30% for individual satellite overpasses. The methodology is presently limited to boundary layer not raining convective clouds of at least 1 km depth that are not obscured by upper layer clouds, including semitransparent cirrus. Finally, the limitation for small solar backscattering angles of <25° restricts the satellite coverage to ~25% of the world area in a single day.« less

  9. Satellite retrieval of cloud condensation nuclei concentrations by using clouds as CCN chambers

    DOE PAGES

    Rosenfeld, Daniel; Zheng, Youtong; Hashimshoni, Eyal; ...

    2016-03-04

    Quantifying the aerosol/cloud-mediated radiative effect at a global scale requires simultaneous satellite retrievals of cloud condensation nuclei (CCN) concentrations and cloud base updraft velocities ( Wb). Hitherto, the inability to do so has been a major cause of high uncertainty regarding anthropogenic aerosol/cloud-mediated radiative forcing. This can be addressed by the emerging capability of estimating CCN and Wb of boundary layer convective clouds from an operational polar orbiting weather satellite. In this paper, our methodology uses such clouds as an effective analog for CCN chambers. The cloud base supersaturation ( S) is determined by Wb and the satellite-retrieved cloud basemore » drop concentrations ( Ndb), which is the same as CCN(S). Validation against ground-based CCN instruments at Oklahoma, at Manaus, and onboard a ship in the northeast Pacific showed a retrieval accuracy of ±25% to ±30% for individual satellite overpasses. The methodology is presently limited to boundary layer not raining convective clouds of at least 1 km depth that are not obscured by upper layer clouds, including semitransparent cirrus. Finally, the limitation for small solar backscattering angles of <25° restricts the satellite coverage to ~25% of the world area in a single day.« less

  10. Impact of aerosol intrusions on sea-ice melting rates and the structure Arctic boundary layer clouds

    NASA Astrophysics Data System (ADS)

    Cotton, W.; Carrio, G.; Jiang, H.

    2003-04-01

    The Los Alamos National Laboratory sea-ice model (LANL CICE) was implemented into the real-time and research versions of the Colorado State University-Regional Atmospheric Modeling System (RAMS@CSU). The original version of CICE was modified in its structure to allow module communication in an interactive multigrid framework. In addition, some improvements have been made in the routines involved in the coupling, among them, the inclusion of iterative methods that consider variable roughness lengths for snow-covered ice thickness categories. This version of the model also includes more complex microphysics that considers the nucleation of cloud droplets, allowing the prediction of mixing ratios and number concentrations for all condensed water species. The real-time version of RAMS@CSU automatically processes the NASA Team SSMI F13 25km sea-ice coverage data; the data are objectively analyzed and mapped to the model grid configuration. We performed two types of cloud resolving simulations to assess the impact of the entrainment of aerosols from above the inversion on Arctic boundary layer clouds. The first series of numerical experiments corresponds to a case observed on May 4 1998 during the FIRE-ACE/SHEBA field experiment. Results indicate a significant impact on the microstructure of the simulated clouds. When assuming polluted initial profiles above the inversion, the liquid water fraction of the cloud monotonically decreases, the total condensate paths increases and downward IR tends to increase due to a significant increase in the ice water path. The second set of cloud resolving simulations focused on the evaluation of the potential effect of aerosol concentration above the inversion on melting rates during spring-summer period. For these multi-month simulations, the IFN and CCN profiles were also initialized assuming the 4 May profiles as benchmarks. Results suggest that increasing the aerosol concentrations above the boundary layer increases sea-ice melting

  11. Observational constraints on Arctic boundary-layer clouds, surface moisture and sensible heat fluxes

    NASA Astrophysics Data System (ADS)

    Wu, D. L.; Boisvert, L.; Klaus, D.; Dethloff, K.; Ganeshan, M.

    2016-12-01

    The dry, cold environment and dynamic surface variations make the Arctic a unique but difficult region for observations, especially in the atmospheric boundary layer (ABL). Spaceborne platforms have been the key vantage point to capture basin-scale changes during the recent Arctic warming. Using the AIRS temperature, moisture and surface data, we found that the Arctic surface moisture flux (SMF) had increased by 7% during 2003-2013 (18 W/m2 equivalent in latent heat), mostly in spring and fall near the Arctic coastal seas where large sea ice reduction and sea surface temperature (SST) increase were observed. The increase in Arctic SMF correlated well with the increases in total atmospheric column water vapor and low-level clouds, when compared to CALIPSO cloud observations. It has been challenging for climate models to reliably determine Arctic cloud radiative forcing (CRF). Using the regional climate model HIRHAM5 and assuming a more efficient Bergeron-Findeisen process with generalized subgrid-scale variability for total water content, we were able to produce a cloud distribution that is more consistent with the CloudSat/CALIPSO observations. More importantly, the modified schemes decrease (increase) the cloud water (ice) content in mixed-phase clouds, which help to improve the modeled CRF and energy budget at the surface, because of the dominant role of the liquid water in CRF. Yet, the coupling between Arctic low clouds and the surface is complex and has strong impacts on ABL. Studying GPS/COSMIC radio occultation (RO) refractivity profiles in the Arctic coldest and driest months, we successfully derived ABL inversion height and surface-based inversion (SBI) frequency, and they were anti-correlated over the Arctic Ocean. For the late summer and early fall season, we further analyzed Japanese R/V Mirai ship measurements and found that the open-ocean surface sensible heat flux (SSHF) can explain 10 % of the ABL height variability, whereas mechanisms such as cloud

  12. Marine Boundary Layer Cloud Property Retrievals from High-Resolution ASTER Observations: Case Studies and Comparison with Terra MODIS

    NASA Technical Reports Server (NTRS)

    Werner, Frank; Wind, Galina; Zhang, Zhibo; Platnick, Steven; Di Girolamo, Larry; Zhao, Guangyu; Amarasinghe, Nandana; Meyer, Kerry

    2016-01-01

    A research-level retrieval algorithm for cloud optical and microphysical properties is developed for the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) aboard the Terra satellite. It is based on the operational MODIS algorithm. This paper documents the technical details of this algorithm and evaluates the retrievals for selected marine boundary layer cloud scenes through comparisons with the operational MODIS Data Collection 6 (C6) cloud product. The newly developed, ASTERspecific cloud masking algorithm is evaluated through comparison with an independent algorithm reported in Zhao and Di Girolamo (2006). To validate and evaluate the cloud optical thickness (tau) and cloud effective radius (r(sub eff)) from ASTER, the high-spatial-resolution ASTER observations are first aggregated to the same 1000m resolution as MODIS. Subsequently, tau(sub aA) and r(sub eff, aA) retrieved from the aggregated ASTER radiances are compared with the collocated MODIS retrievals. For overcast pixels, the two data sets agree very well with Pearson's product-moment correlation coefficients of R greater than 0.970. However, for partially cloudy pixels there are significant differences between r(sub eff, aA) and the MODIS results which can exceed 10 micrometers. Moreover, it is shown that the numerous delicate cloud structures in the example marine boundary layer scenes, resolved by the high-resolution ASTER retrievals, are smoothed by the MODIS observations. The overall good agreement between the research-level ASTER results and the operational MODIS C6 products proves the feasibility of MODIS-like retrievals from ASTER reflectance measurements and provides the basis for future studies concerning the scale dependency of satellite observations and three-dimensional radiative effects.

  13. Marine boundary layer cloud property retrievals from high-resolution ASTER observations: case studies and comparison with Terra MODIS

    NASA Astrophysics Data System (ADS)

    Werner, Frank; Wind, Galina; Zhang, Zhibo; Platnick, Steven; Di Girolamo, Larry; Zhao, Guangyu; Amarasinghe, Nandana; Meyer, Kerry

    2016-12-01

    A research-level retrieval algorithm for cloud optical and microphysical properties is developed for the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) aboard the Terra satellite. It is based on the operational MODIS algorithm. This paper documents the technical details of this algorithm and evaluates the retrievals for selected marine boundary layer cloud scenes through comparisons with the operational MODIS Data Collection 6 (C6) cloud product. The newly developed, ASTER-specific cloud masking algorithm is evaluated through comparison with an independent algorithm reported in [Zhao and Di Girolamo(2006)]. To validate and evaluate the cloud optical thickness (τ) and cloud effective radius (reff) from ASTER, the high-spatial-resolution ASTER observations are first aggregated to the same 1000 m resolution as MODIS. Subsequently, τaA and reff, aA retrieved from the aggregated ASTER radiances are compared with the collocated MODIS retrievals. For overcast pixels, the two data sets agree very well with Pearson's product-moment correlation coefficients of R > 0.970. However, for partially cloudy pixels there are significant differences between reff, aA and the MODIS results which can exceed 10 µm. Moreover, it is shown that the numerous delicate cloud structures in the example marine boundary layer scenes, resolved by the high-resolution ASTER retrievals, are smoothed by the MODIS observations. The overall good agreement between the research-level ASTER results and the operational MODIS C6 products proves the feasibility of MODIS-like retrievals from ASTER reflectance measurements and provides the basis for future studies concerning the scale dependency of satellite observations and three-dimensional radiative effects.

  14. Evaluation of Satellite-Based Upper Troposphere Cloud Top Height Retrievals in Multilayer Cloud Conditions During TC4

    NASA Technical Reports Server (NTRS)

    Chang, Fu-Lung; Minnis, Patrick; Ayers, J. Kirk; McGill, Matthew J.; Palikonda, Rabindra; Spangenberg, Douglas A.; Smith, William L., Jr.; Yost, Christopher R.

    2010-01-01

    Upper troposphere cloud top heights (CTHs), restricted to cloud top pressures (CTPs) less than 500 hPa, inferred using four satellite retrieval methods applied to Twelfth Geostationary Operational Environmental Satellite (GOES-12) data are evaluated using measurements during the July August 2007 Tropical Composition, Cloud and Climate Coupling Experiment (TC4). The four methods are the single-layer CO2-absorption technique (SCO2AT), a modified CO2-absorption technique (MCO2AT) developed for improving both single-layered and multilayered cloud retrievals, a standard version of the Visible Infrared Solar-infrared Split-window Technique (old VISST), and a new version of VISST (new VISST) recently developed to improve cloud property retrievals. They are evaluated by comparing with ER-2 aircraft-based Cloud Physics Lidar (CPL) data taken during 9 days having extensive upper troposphere cirrus, anvil, and convective clouds. Compared to the 89% coverage by upper tropospheric clouds detected by the CPL, the SCO2AT, MCO2AT, old VISST, and new VISST retrieved CTPs less than 500 hPa in 76, 76, 69, and 74% of the matched pixels, respectively. Most of the differences are due to subvisible and optically thin cirrus clouds occurring near the tropopause that were detected only by the CPL. The mean upper tropospheric CTHs for the 9 days are 14.2 (+/- 2.1) km from the CPL and 10.7 (+/- 2.1), 12.1 (+/- 1.6), 9.7 (+/- 2.9), and 11.4 (+/- 2.8) km from the SCO2AT, MCO2AT, old VISST, and new VISST, respectively. Compared to the CPL, the MCO2AT CTHs had the smallest mean biases for semitransparent high clouds in both single-layered and multilayered situations whereas the new VISST CTHs had the smallest mean biases when upper clouds were opaque and optically thick. The biases for all techniques increased with increasing numbers of cloud layers. The transparency of the upper layer clouds tends to increase with the numbers of cloud layers.

  15. Evaluating stratiform cloud base charge remotely

    NASA Astrophysics Data System (ADS)

    Harrison, R. Giles; Nicoll, Keri A.; Aplin, Karen L.

    2017-06-01

    Stratiform clouds acquire charge at their upper and lower horizontal boundaries due to vertical current flow in the global electric circuit. Cloud charge is expected to influence microphysical processes, but understanding is restricted by the infrequent in situ measurements available. For stratiform cloud bases below 1 km in altitude, the cloud base charge modifies the surface electric field beneath, allowing a new method of remote determination. Combining continuous cloud height data during 2015-2016 from a laser ceilometer with electric field mill data, cloud base charge is derived using a horizontal charged disk model. The median daily cloud base charge density found was -0.86 nC m-2 from 43 days' data. This is consistent with a uniformly charged region 40 m thick at the cloud base, now confirming that negative cloud base charge is a common feature of terrestrial layer clouds. This technique can also be applied to planetary atmospheres and volcanic plumes.Plain Language SummaryThe idea that <span class="hlt">clouds</span> in the atmosphere can charge electrically has been appreciated since the time of Benjamin Franklin, but it is less widely recognized that it is not just thunderclouds which contain electric charge. For example, water droplets in simple <span class="hlt">layer</span> <span class="hlt">clouds</span>, that are abundant and often responsible for an overcast day, carry electric charges. The droplet charging arises at the upper and lower edges of the <span class="hlt">layer</span> <span class="hlt">cloud</span>. This occurs because the small droplets at the edges draw charge from the air outside the <span class="hlt">cloud</span>. Understanding how strongly <span class="hlt">layer</span> <span class="hlt">clouds</span> charge is important in evaluating electrical effects on the development of such <span class="hlt">clouds</span>, for example, how thick the <span class="hlt">cloud</span> becomes and whether it generates rain. Previously, <span class="hlt">cloud</span> charge measurement has required direct measurements within the <span class="hlt">cloud</span> using weather balloons or aircraft. This work has monitored the lower <span class="hlt">cloud</span> charge continuously using instruments placed at the surface beneath</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/1411917-instantaneous-linkages-between-clouds-large-scale-meteorology-over-southern-ocean-observations-climate-model','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/1411917-instantaneous-linkages-between-clouds-large-scale-meteorology-over-southern-ocean-observations-climate-model"><span>Instantaneous Linkages between <span class="hlt">Clouds</span> and Large-Scale Meteorology over the Southern Ocean in Observations and a Climate Model</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Wall, Casey J.; Hartmann, Dennis L.; Ma, Po-Lun</p> <p></p> <p>Instantaneous, coincident, footprint-level satellite observations of <span class="hlt">cloud</span> properties and radiation taken during austral summer over the Southern Ocean are used to study relationships between <span class="hlt">clouds</span> and large-scale meteorology. <span class="hlt">Cloud</span> properties are very sensitive to the strength of vertical motion in the <span class="hlt">middle</span>-troposphere, and low-<span class="hlt">cloud</span> properties are sensitive to estimated inversion strength, low-level temperature advection, and sea surface temperature. These relationships are quantified. An index for the meteorological anomalies associated with midlatitude cyclones is presented, and it is used to reveal the sensitivity of <span class="hlt">clouds</span> to the meteorology within the warm- and cold-sector of cyclones. The observed relationships between <span class="hlt">clouds</span> andmore » meteorology are compared to those in the Community Atmosphere Model version 5 (CAM5) using satellite simulators. Low-<span class="hlt">clouds</span> simulated by CAM5 are too few, too bright, and contain too much ice, and low-<span class="hlt">clouds</span> located in the cold-sector of cyclones are too sensitive to variations in the meteorology. The latter two biases are dramatically reduced when CAM5 is coupled with an updated boundary <span class="hlt">layer</span> parameterization know as <span class="hlt">Cloud</span> <span class="hlt">Layers</span> Unified by Binormals (CLUBB). More generally, this study demonstrates that examining the instantaneous timescale is a powerful approach to understanding the physical processes that control <span class="hlt">clouds</span> and how they are represented in climate models. Such an evaluation goes beyond the <span class="hlt">cloud</span> climatology and exposes model bias under various meteorological conditions.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018EML....14..319N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018EML....14..319N"><span><span class="hlt">Middle</span> Electrode in a Vertical Transistor Structure Using an Sn <span class="hlt">Layer</span> by Thermal Evaporation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nogueira, Gabriel Leonardo; da Silva Ozório, Maiza; da Silva, Marcelo Marques; Morais, Rogério Miranda; Alves, Neri</p> <p>2018-05-01</p> <p>We report a process for performing the <span class="hlt">middle</span> electrode for a vertical field effect transistor (VOFET) by the evaporation of a tin (Sn) <span class="hlt">layer</span>. Bare aluminum oxide (Al2O3), obtained by anodization, and Al2O3 covered with a polymethylmethacrylate (PMMA) <span class="hlt">layer</span> were used as the gate dielectric. We measured the electrical resistance of Sn while the evaporation was carried out to find the best condition to prepare the <span class="hlt">middle</span> electrode, that is, good lateral conduction associated with openings that give permeability to the electric field in a vertical direction. This process showed that 55 nm Sn thick is suitable for use in a VOFET, being easier to achieve optimal thickness when the Sn is evaporated onto PMMA than onto bare Al2O3. The addition of a PMMA <span class="hlt">layer</span> on the Al2O3 surface modifies the morphology of the Sn <span class="hlt">layer</span>, resulting in a lowering of the threshold voltage. The values of threshold voltage and electric field, VTH = - 8 V and ETH = 354.5 MV/m respectively, were calculated using an Al2O3 film 20 nm thick covered with a 14 nm PMMA <span class="hlt">layer</span> as gate dielectric, while for bare Al2O3 these values were VTH = - 10 V and ETH = 500 MV/m.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/1132726-transitions-cloud-topped-marine-boundary-layers-characterized-airs-modis-large-eddy-simulation-model','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/1132726-transitions-cloud-topped-marine-boundary-layers-characterized-airs-modis-large-eddy-simulation-model"><span>Transitions of <span class="hlt">cloud</span>-topped marine boundary <span class="hlt">layers</span> characterized by AIRS, MODIS, and a large eddy simulation model</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Yue, Qing; Kahn, Brian; Xiao, Heng</p> <p>2013-08-16</p> <p><span class="hlt">Cloud</span> top entrainment instability (CTEI) is a hypothesized positive feedback between entrainment mixing and evaporative cooling near the <span class="hlt">cloud</span> top. Previous theoretical and numerical modeling studies have shown that the persistence or breakup of marine boundary <span class="hlt">layer</span> (MBL) <span class="hlt">clouds</span> may be sensitive to the CTEI parameter. Collocated thermodynamic profile and <span class="hlt">cloud</span> observations obtained from the Atmospheric Infrared Sounder (AIRS) and Moderate Resolution Imaging Spectroradiometer (MODIS) instruments are used to quantify the relationship between the CTEI parameter and the <span class="hlt">cloud</span>-topped MBL transition from stratocumulus to trade cumulus in the northeastern Pacific Ocean. Results derived from AIRS and MODIS are compared withmore » numerical results from the UCLA large eddy simulation (LES) model for both well-mixed and decoupled MBLs. The satellite and model results both demonstrate a clear correlation between the CTEI parameter and MBL <span class="hlt">cloud</span> fraction. Despite fundamental differences between LES steady state results and the instantaneous snapshot type of observations from satellites, significant correlations for both the instantaneous pixel-scale observations and the long-term averaged spatial patterns between the CTEI parameter and MBL <span class="hlt">cloud</span> fraction are found from the satellite observations and are consistent with LES results. This suggests the potential of using AIRS and MODIS to quantify global and temporal characteristics of the <span class="hlt">cloud</span>-topped MBL transition.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20080006610','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20080006610"><span>Ice <span class="hlt">Cloud</span> Properties in Ice-Over-Water <span class="hlt">Cloud</span> Systems Using TRMM VIRS and TMI Data</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Minnis, Patrick; Huang, Jianping; Lin, Bing; Yi, Yuhong; Arduini, Robert F.; Fan, Tai-Fang; Ayers, J. Kirk; Mace, Gerald G.</p> <p>2007-01-01</p> <p>A multi-<span class="hlt">layered</span> <span class="hlt">cloud</span> retrieval system (MCRS) is updated and used to estimate ice water path in maritime ice-over-water <span class="hlt">clouds</span> 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 <span class="hlt">cloud</span> systems using radiative transfer calculations with various combinations of ice-over-water <span class="hlt">cloud</span> <span class="hlt">layers</span>. 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 <span class="hlt">cloud</span> properties to select the proper lookup table. The properties of the upper-level ice <span class="hlt">clouds</span>, 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-<span class="hlt">cloud</span> 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 <span class="hlt">clouds</span> by 42% and 13% compared to using the single-<span class="hlt">layer</span> VISST and an earlier simplified MW-VIS-IR (MVI) differencing method, respectively, for ice-over-water <span class="hlt">cloud</span> systems. The tropical distribution of ice-over-water <span class="hlt">clouds</span> 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-<span class="hlt">layered</span> <span class="hlt">layered</span> <span class="hlt">clouds</span> by 7% and 11%, respectively. The mean IWP from the MCRS is 8-14% greater than that retrieved from radar retrievals of overlapped <span class="hlt">clouds</span> over two surface sites and the standard deviations of the differences are similar to those for single-<span class="hlt">layered</span> <span class="hlt">clouds</span>. Examples</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://eric.ed.gov/?q=cloud+AND+computing&pg=7&id=EJ878712','ERIC'); return false;" href="https://eric.ed.gov/?q=cloud+AND+computing&pg=7&id=EJ878712"><span>A View from the <span class="hlt">Clouds</span></span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Chudnov, Daniel</p> <p>2010-01-01</p> <p><span class="hlt">Cloud</span> computing is definitely a thing now, but it's not new and it's not even novel. Back when people were first learning about the Internet in the 1990s, every diagram that one saw showing how the Internet worked had a big <span class="hlt">cloud</span> in the <span class="hlt">middle</span>. That <span class="hlt">cloud</span> represented the diverse links, routers, gateways, and protocols that passed traffic around in…</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active"><span>9</span></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_9 --> <div id="page_10" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="181"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20170003361','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20170003361"><span>Testing the Two-<span class="hlt">Layer</span> Model for Correcting Near <span class="hlt">Cloud</span> Reflectance Enhancement Using LES SHDOM Simulated Radiances</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wen, Guoyong; Marshak, Alexander; Varnai, Tamas; Levy, Robert</p> <p>2016-01-01</p> <p>A transition zone exists between cloudy skies and clear sky; such that, <span class="hlt">clouds</span> scatter solar radiation into clear-sky regions. From a satellite perspective, it appears that <span class="hlt">clouds</span> enhance the radiation nearby. We seek a simple method to estimate this enhancement, since it is so computationally expensive to account for all three-dimensional (3-D) scattering processes. In previous studies, we developed a simple two-<span class="hlt">layer</span> model (2LM) that estimated the radiation scattered via <span class="hlt">cloud</span>-molecular interactions. Here we have developed a new model to account for <span class="hlt">cloud</span>-surface interaction (CSI). We test the models by comparing to calculations provided by full 3-D radiative transfer simulations of realistic <span class="hlt">cloud</span> scenes. For these scenes, the Moderate Resolution Imaging Spectroradiometer (MODIS)-like radiance fields were computed from the Spherical Harmonic Discrete Ordinate Method (SHDOM), based on a large number of cumulus fields simulated by the University of California, Los Angeles (UCLA) large eddy simulation (LES) model. We find that the original 2LM model that estimates <span class="hlt">cloud</span>-air molecule interactions accounts for 64 of the total reflectance enhancement and the new model (2LM+CSI) that also includes <span class="hlt">cloud</span>-surface interactions accounts for nearly 80. We discuss the possibility of accounting for <span class="hlt">cloud</span>-aerosol radiative interactions in 3-D <span class="hlt">cloud</span>-induced reflectance enhancement, which may explain the remaining 20 of enhancements. Because these are simple models, these corrections can be applied to global satellite observations (e.g., MODIS) and help to reduce biases in aerosol and other clear-sky retrievals.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.A41O..02A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.A41O..02A"><span><span class="hlt">Cloud</span> System Evolution in the Trades—CSET</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Albrecht, B. A.; Zuidema, P.; Bretherton, C. S.; Wood, R.; Ghate, V. P.</p> <p>2015-12-01</p> <p>The <span class="hlt">Cloud</span> System Evolution in the Trades (CSET) study was designed to describe and explain the evolution of the boundary <span class="hlt">layer</span> aerosol, <span class="hlt">cloud</span>, and thermodynamic structures along trajectories within the north-Pacific trade-winds. The observational component of this study centered on 7 round-trips made by the NSF NCAR Gulfstream V (GV) between Sacramento, CA and Kona, Hawaii between 1 July and 15 August 2015. The CSET observing strategy used a Lagrangian approach to sample aerosol, <span class="hlt">cloud</span>, and boundary <span class="hlt">layer</span> properties upwind from the transition zone over the North Pacific and to resample these areas two days later. GFS forecast trajectories were used to plan the outbound flight to Hawaii and then updated forecast trajectories helped set the return flight plan two days later. Two key elements of the CSET observing system were the newly developed HIAPER <span class="hlt">Cloud</span> Radar (HCR) and the HIAPER Spectral Resolution Lidar (HSRL). Together they provided unprecedented characterizations of aerosol, <span class="hlt">cloud</span> and precipitation structures. A full suite of probes on the aircraft were used for in situ measurements of aerosol, <span class="hlt">cloud</span>, precipitation, and turbulence properties during the low-level aircraft profiling portions of the flights. A wide range of boundary <span class="hlt">layer</span> structures and aerosol, <span class="hlt">cloud</span>, and precipitation conditions were observed during CSET. The <span class="hlt">cloud</span> systems sampled included solid stratocumulus infused with smoke from Canadian wildfires, mesoscale (100-200 km) <span class="hlt">cloud</span>-precipitation complexes, and patches of shallow cumuli in environments with accumulation mode aerosol concentrations of less than 50 cm-3. Ultra clean <span class="hlt">layers</span> (UCLs with accumulation mode concentrations of less than 10 cm-3) were observed frequently near the top of the boundary <span class="hlt">layer</span> and were often associated with shallow, gray (optically thin) <span class="hlt">layered</span> clouds—features that are the subject of focused investigations by the CSET science team. The extent of aerosol, <span class="hlt">cloud</span>, drizzle and boundary <span class="hlt">layer</span> sampling that was</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20040112011','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20040112011"><span><span class="hlt">Cloud</span> Detection Using Measured and Modeled State Parameters</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Yi, Y.; Minnis, P.; Huang, J.; Ayers, J. K.; Doelling, D. R.; Khaiyer, M. M.; Nordeen, M. L.</p> <p>2004-01-01</p> <p>In this study, hourly RUC analyses were used to examine the differences between RH and temperature values from RUC reanalysis data and from radiosonde atmospheric profiles obtained at the ARM SCF. The results show that the temperature observations from the SONDE and RUC are highly correlated. The RHs are also well-correlated, but the SONDE values generally exceed those from RUC. Inside <span class="hlt">cloud</span> <span class="hlt">layers</span>, the RH from RUC is 2-14% lower than the RH from SONDE for all RUC <span class="hlt">layers</span>. Although the <span class="hlt">layer</span> mean RH within <span class="hlt">clouds</span> is much greater than the <span class="hlt">layer</span> mean RH outside <span class="hlt">cloud</span> or in the clear-sky, RH thresholds chosen as a function of temperature can more accurately diagnose <span class="hlt">cloud</span> occurrence for either dataset. For overcast <span class="hlt">clouds</span>, it was found that the 50% probability RH threshold for diagnosing a <span class="hlt">cloud</span>, within a given upper tropospheric <span class="hlt">layer</span> is roughly 90% for the Vaisala RS80-15LH radisonde and 80% for RUC data. While for the partial <span class="hlt">cloud</span> (<span class="hlt">cloud</span> amount is less than 90%), the RH thresholds of SONDE are close to RUC for a given probability in upper tropospheric <span class="hlt">layers</span>. The probabilities of detecting <span class="hlt">clouds</span> at a given RH and temperature should be useful for a variety of application such as the development of new <span class="hlt">cloud</span> parameterizations or for estimating the vertical profile of cloudiness underneath a given <span class="hlt">cloud</span> observed from the satellite to construct a 3-D <span class="hlt">cloud</span> data set for computing atmospheric radiative heating profiles or determining potential aircraft icing conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010cosp...38.1213L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010cosp...38.1213L"><span>Trends and solar cycle effects in mesospheric ice <span class="hlt">clouds</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lübken, Franz-Josef; Berger, Uwe; Fiedler, Jens; Baumgarten, Gerd; Gerding, Michael</p> <p></p> <p>Lidar observations of mesospheric ice <span class="hlt">layers</span> (noctilucent <span class="hlt">clouds</span>, NLC) are now available since 12 years which allows to study solar cycle effects on NLC parameters such as altitudes, bright-ness, and occurrence rates. We present observations from our lidar stations in Kuehlungsborn (54N) and ALOMAR (69N). Different from general expectations the mean <span class="hlt">layer</span> characteris-tics at ALOMAR do not show a persistent anti-correlation with solar cycle. Although a nice anti-correlation of Ly-alpha and occurrence rates is detected in the first half of the solar cycle, occurrence rates decreased with decreasing solar activity thereafter. Interestingly, in summer 2009 record high NLC parameters were detected as expected in solar minimum conditions. The morphology of NLC suggests that other processes except solar radiation may affect NLC. We have recently applied our LIMA model to study in detail the solar cycle effects on tempera-tures and water vapor concentration the <span class="hlt">middle</span> atmosphere and its subsequent influence on mesospheric ice <span class="hlt">clouds</span>. Furthermore, lower atmosphere effects are implicitly included because LIMA nudges to the conditions in the troposphere and lower stratosphere. We compare LIMA results regarding solar cycle effects on temperatures and ice <span class="hlt">layers</span> with observations at ALO-MAR as well as satellite borne measurements. We will also present LIMA results regarding the latitude variation of solar cycle and trends, including a comparison of northern and southern hemisphere. We have adapted the observation conditions from SBUV (wavelength and scatter-ing angle) in LIMA for a detailed comparison with long term observations of ice <span class="hlt">clouds</span> from satellites.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.A41J..06M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.A41J..06M"><span>Lagrangian evolution of the marine boundary <span class="hlt">layer</span> from the <span class="hlt">Cloud</span> System Evolution in the Trades (CSET) campaign</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mohrmann, J.; Ghate, V. P.; McCoy, I. L.; Bretherton, C. S.; Wood, R.; Minnis, P.; Palikonda, R.</p> <p>2017-12-01</p> <p>The <span class="hlt">Cloud</span> System Evolution in the Trades (CSET) field campaign took place July/August 2015 to study the evolution of <span class="hlt">clouds</span>, precipitation, and aerosols in the stratocumulus-to-cumulus (Sc-Cu) transition region of the northeast Pacific marine boundary <span class="hlt">layer</span> (MBL). Aircraft observations sampled across a wide range of <span class="hlt">cloud</span> and aerosol conditions. The sampling strategy, where MBL airmasses were sampled with the NSF/NCAR Gulfstream-V (HIAPER) and resampled then at their advected location two days later, resulted in a dataset of 14 paired flights suitable for Lagrangian analysis. This analysis shows that Lagrangian coherence of long-lived species (namely CO and O3) across 48 hours are high, but that of subcloud aerosol, MBL depth, and <span class="hlt">cloud</span> properties is limited. Geostationary satellite retrievals are compared against aircraft observations; these are combined with reanalysis data and HYSPLIT trajectories to document the Lagrangian evolution of <span class="hlt">cloud</span> fraction, <span class="hlt">cloud</span> droplet number concentration, liquid water path, estimated inversion strength (EIS), and MBL depth, which are used to expand upon and validate the aircraft-based analysis. Many of the trajectories sampled by the aircraft show a clear Sc-Cu transition. Although satellite <span class="hlt">cloud</span> fraction and EIS were found to be strongly spatiotemporally correlated, changes in MBL <span class="hlt">cloud</span> fraction along trajectories did not correlate with any measure of EIS forcing.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..19.5166K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..19.5166K"><span><span class="hlt">Cloud</span> level winds from UV and IR images obtained by VMC onboard Venus Express</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Khatuntsev, Igor; Patsaeva, Marina; Titov, Dmitri; Ignatiev, Nikolay; Turin, Alexander; Bertaux, Jean-Loup</p> <p>2017-04-01</p> <p>During eight years Venus Monitoring Camera (VMC) [1] onboard the Venus Express orbiter has observed the upper <span class="hlt">cloud</span> <span class="hlt">layer</span> of Venus. The largest set of images was obtained in the UV (365 nm), visible (513 nm) and two infrared channels - 965 nm and 1010 nm. The UV dayside images were used to study the atmospheric circulation at the Venus <span class="hlt">cloud</span> tops [2], [3]. Mean zonal and meridional profiles of winds and their variability were derived from <span class="hlt">cloud</span> tracking of UV images. In low latitudes the mean retrograde zonal wind at the <span class="hlt">cloud</span> top (67±2 km) is about 95 m/s with a maximum of about 102 m/s at 40-50°S. Poleward from 50°S the zonal wind quickly fades out with latitude. The mean poleward meridional wind slowly increases from zero value at the equator to about 10 m/s at 50°S. Poleward from this latitude, the absolute value of the meridional component monotonically decreases to zero at the pole. The VMC observations suggest clear diurnal signature in the wind field. They also indicate a long term trend for the zonal wind speed at low latitudes to increase from 85 m/s in the beginning of the mission to 110 m/s by the <span class="hlt">middle</span> of 2012. The trend was explained by influence of the surface topography on the zonal flow [4]. <span class="hlt">Cloud</span> features tracking in the IR images provided information about winds in the <span class="hlt">middle</span> <span class="hlt">cloud</span> deck (55±4 km). In the low and <span class="hlt">middle</span> latitudes (5-65°S) the IR mean retrograde zonal velocity is about 68-70 m/s. In contrast to poleward flow at the <span class="hlt">cloud</span> tops, equatorward motions dominate in the <span class="hlt">middle</span> <span class="hlt">cloud</span> with maximum speed of 5.8±1.2 m/s at latitude 15°S. The meridional speed slowly decreases to 0 at 65-70°S. At low latitudes the zonal and meridional speed demonstrate long term variations. Following [4] we explain the observed long term trend of zonal and meridional components by the influence of surface topography of highland region Aphrodite Terra on dynamic processes in the <span class="hlt">middle</span> <span class="hlt">cloud</span> deck through gravity waves. Acknowledgements: I.V. Khatuntsev</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008JGRD..11324207W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008JGRD..11324207W"><span>Importance of molecular Rayleigh scattering in the enhancement of clear sky reflectance in the vicinity of boundary <span class="hlt">layer</span> cumulus <span class="hlt">clouds</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wen, Guoyong; Marshak, Alexander; Cahalan, Robert F.</p> <p>2008-12-01</p> <p><span class="hlt">Clouds</span> increase the complexity of atmospheric radiative transfer processes, particularly for aerosol retrievals in clear regions in the vicinity of <span class="hlt">clouds</span>. This study focuses on identifying mechanisms responsible for the enhancement of nadir reflectance in clear regions in the vicinity of cumulus <span class="hlt">clouds</span> and quantifies the relative importance of each mechanism. Using <span class="hlt">cloud</span> optical properties and surface albedo derived from Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and Moderate Resolution Imaging Spectroradiometer (MODIS), we performed extensive Monte Carlo simulations of radiative transfer in two cumulus scenes in a biomass burning region in Brazil. The results show that the scattering of radiation by <span class="hlt">clouds</span>, followed by upward Rayleigh scattering by molecules above <span class="hlt">cloud</span> top over clear gaps, is the dominant mechanism for the enhancement of visible reflectance in clear regions in boundary <span class="hlt">layer</span> cumulus field over dark surfaces with aerosols trapped in the boundary <span class="hlt">layer</span>. The Rayleigh scattering contributes ˜80% and ˜50% to the total enhancement for wavelengths 0.47 μm (with aerosol optical thickness 0.2) and 0.66 μm (with aerosol optical thickness 0.1), respectively. Out of the total contribution of molecular scattering, ˜90% arises from the clear atmosphere above <span class="hlt">cloud</span> top height. The mechanism is valid for a large range of aerosol optical thicknesses (up to 1 in this study) for 0.47 μm, and for aerosol optical thickness up to 0.2 for 0.66 μm. Our results provide a basis to develop simplifications for future aerosol remote sensing from satellite.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.A43M..01L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.A43M..01L"><span><span class="hlt">Cloud</span> vertical structure, precipitation, and <span class="hlt">cloud</span> radiative effects over Tibetan Plateau</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Liu, Y.; Yan, Y.; Lu, J.</p> <p>2017-12-01</p> <p>The vertical structure of <span class="hlt">clouds</span> and its connection with precipitation and <span class="hlt">cloud</span> radiative effects (CRE) over the Tibetan Plateau (TP) are analyzed and compared with its neighboring land and tropical oceans based on <span class="hlt">Cloud</span>Sat and <span class="hlt">Cloud</span>-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) products and the Tropical Rainfall Measuring Mission (TRMM) precipitation data. Unique characteristics of <span class="hlt">cloud</span> vertical structure and CRE over the TP are found. The <span class="hlt">cloud</span> amount shows seasonal variation over the TP, which presents a single peak (located in 7-11 km) during January to April and two peaks (located in 5-8 km and 11-17 km separately) after mid-June, and then resumes to one peak (located in 5-10 km) after mid-August. Topography-induced restriction on moisture supply leads to a compression effect on <span class="hlt">clouds</span>, i.e., the reduction in both <span class="hlt">cloud</span> thickness and number of <span class="hlt">cloud</span> <span class="hlt">layers</span>, over the TP. The topography-induced compression effect is also shown in the range in the variation of <span class="hlt">cloud</span> thickness and <span class="hlt">cloud</span>-top height corresponding to different precipitation intensity, which is much smaller over the TP than its neighboring regions. In summer, <span class="hlt">cloud</span> ice particles over the TP are mostly located at lower altitude (5-10 km) with richer variety of sizes and aggregation in no rain conditions compared to other regions. Ice water content becomes abundant and the number concentration tends to be dense at higher levels when precipitation is enhanced. The longwave CRE in the atmosphere over the TP is a net cooling effect. The vertical structure of CRE over the TP is unique compared to other regions: there exists a strong cooling <span class="hlt">layer</span> of net CRE at the altitude of 8 km, from June to the beginning of October; the net radiative heating <span class="hlt">layer</span> above the surface is shallower but stronger underneath 7 km and with a stronger seasonal variation over the TP.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20150002801&hterms=Sun-Mack&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAuthor-Name%26N%3D0%26No%3D10%26Ntt%3DSun-Mack','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20150002801&hterms=Sun-Mack&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAuthor-Name%26N%3D0%26No%3D10%26Ntt%3DSun-Mack"><span>Comparison of Marine Boundary <span class="hlt">Layer</span> <span class="hlt">Cloud</span> Properties from CERES-MODIS Edition 4 and DOE ARM AMF Measurements at the Azores</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Xi, Baike; Dong, Xiquan; Minnis, Patrick; Sun-Mack, Sunny</p> <p>2014-01-01</p> <p>Marine boundary <span class="hlt">layer</span> (MBL) <span class="hlt">cloud</span> properties derived from the NASA <span class="hlt">Clouds</span> and the Earth's Radiant Energy System (CERES) project using Terra and Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) data are compared with observations taken at the Department of Energy Atmospheric Radiation Measurement (ARM) Mobile Facility at the Azores (AMF-Azores) site from June 2009 through December 2010. <span class="hlt">Cloud</span> properties derived from ARM ground-based observations were averaged over a 1 h interval centered at the satellite overpass time, while the CERES-MODIS (CM) results were averaged within a 30 km×30 km grid box centered over the Azores site. A total of 63 daytime and 92 nighttime single-<span class="hlt">layered</span> overcast MBL <span class="hlt">cloud</span> cases were selected from 19 months of ARM radar-lidar and satellite observations. The CM <span class="hlt">cloud</span> top/base heights (Htop/Hbase) were determined from <span class="hlt">cloud</span> top/base temperatures (Ttop/Tbase) using a regional boundary <span class="hlt">layer</span> lapse rate method. For daytime comparisons, the CM-derived Htop (Hbase), on average, is 0.063 km (0.068 km) higher (lower) than its ARM radar-lidar-observed counterpart, and the CM-derived Ttop and Tbase are 0.9 K less and 2.5 K greater than the surface values with high correlations (R(sup 2) = 0.82 and 0.84, respectively). In general, the <span class="hlt">cloud</span> top comparisons agree better than the <span class="hlt">cloud</span> base comparisons, because the CM <span class="hlt">cloud</span> base temperatures and heights are secondary products determined from <span class="hlt">cloud</span> top temperatures and heights. No significant day-night difference was found in the analyses. The comparisons of MBL <span class="hlt">cloud</span> microphysical properties reveal that when averaged over a 30 km× 30 km area, the CM-retrieved <span class="hlt">cloud</span> droplet effective radius (re) at 3.7 micrometers is 1.3 micrometers larger than that from the ARM retrievals (12.8 micrometers), while the CM-retrieved <span class="hlt">cloud</span> liquid water path (LWP) is 13.5 gm( exp -2) less than its ARM counterpart (114.2 gm( exp-2) due to its small optical depth (9.6 versus 13.7). The differences are reduced by 50</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JGRD..119.9509X','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JGRD..119.9509X"><span>Comparison of marine boundary <span class="hlt">layer</span> <span class="hlt">cloud</span> properties from CERES-MODIS Edition 4 and DOE ARM AMF measurements at the Azores</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Xi, Baike; Dong, Xiquan; Minnis, Patrick; Sun-Mack, Sunny</p> <p>2014-08-01</p> <p>Marine boundary <span class="hlt">layer</span> (MBL) <span class="hlt">cloud</span> properties derived from the NASA <span class="hlt">Clouds</span> and the Earth's Radiant Energy System (CERES) project using Terra and Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) data are compared with observations taken at the Department of Energy Atmospheric Radiation Measurement (ARM) Mobile Facility at the Azores (AMF-Azores) site from June 2009 through December 2010. <span class="hlt">Cloud</span> properties derived from ARM ground-based observations were averaged over a 1 h interval centered at the satellite overpass time, while the CERES-MODIS (CM) results were averaged within a 30 km × 30 km grid box centered over the Azores site. A total of 63 daytime and 92 nighttime single-<span class="hlt">layered</span> overcast MBL <span class="hlt">cloud</span> cases were selected from 19 months of ARM radar-lidar and satellite observations. The CM <span class="hlt">cloud</span> top/base heights (Htop/Hbase) were determined from <span class="hlt">cloud</span> top/base temperatures (Ttop/Tbase) using a regional boundary <span class="hlt">layer</span> lapse rate method. For daytime comparisons, the CM-derived Htop (Hbase), on average, is 0.063 km (0.068 km) higher (lower) than its ARM radar-lidar-observed counterpart, and the CM-derived Ttop and Tbase are 0.9 K less and 2.5 K greater than the surface values with high correlations (R2 = 0.82 and 0.84, respectively). In general, the <span class="hlt">cloud</span> top comparisons agree better than the <span class="hlt">cloud</span> base comparisons, because the CM <span class="hlt">cloud</span> base temperatures and heights are secondary products determined from <span class="hlt">cloud</span> top temperatures and heights. No significant day-night difference was found in the analyses. The comparisons of MBL <span class="hlt">cloud</span> microphysical properties reveal that when averaged over a 30 km × 30 km area, the CM-retrieved <span class="hlt">cloud</span> droplet effective radius (re) at 3.7 µm is 1.3 µm larger than that from the ARM retrievals (12.8 µm), while the CM-retrieved <span class="hlt">cloud</span> liquid water path (LWP) is 13.5 gm-2 less than its ARM counterpart (114.2 gm-2) due to its small optical depth (9.6 versus 13.7). The differences are reduced by 50% when the CM averages are computed</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015ACPD...15.1421S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015ACPD...15.1421S"><span>Observations and simulations of three-dimensional radiative interactions between Arctic boundary <span class="hlt">layer</span> <span class="hlt">clouds</span> and ice floes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schäfer, M.; Bierwirth, E.; Ehrlich, A.; Jäkel, E.; Wendisch, M.</p> <p>2015-01-01</p> <p>Based on airborne spectral imaging observations three-dimensional (3-D) radiative effects between Arctic boundary <span class="hlt">layer</span> <span class="hlt">clouds</span> and ice floes have been identified and quantified. A method is presented to discriminate sea ice and open water in case of <span class="hlt">clouds</span> from imaging radiance measurements. This separation simultaneously reveals that in case of <span class="hlt">clouds</span> the transition of radiance between open water and sea ice is not instantaneously but horizontally smoothed. In general, <span class="hlt">clouds</span> reduce the nadir radiance above bright surfaces in the vicinity of sea ice - open water boundaries, while the nadir radiance above dark surfaces is enhanced compared to situations with <span class="hlt">clouds</span> located above horizontal homogeneous surfaces. With help of the observations and 3-D radiative transfer simulations, this effect was quantified to range between 0 and 2200 m distance to the sea ice edge. This affected distance Δ L was found to depend on both, <span class="hlt">cloud</span> and sea ice properties. For a ground overlaying <span class="hlt">cloud</span> in 0-200 m altitude, increasing the <span class="hlt">cloud</span> optical thickness from τ = 1 to τ = 10 decreases Δ L from 600 to 250 m, while increasing <span class="hlt">cloud</span> base altitude or <span class="hlt">cloud</span> geometrical thickness can increase Δ L; Δ L(τ = 1/10) = 2200 m/1250 m for 500-1000 m <span class="hlt">cloud</span> altitude. To quantify the effect for different shapes and sizes of the ice floes, various albedo fields (infinite straight ice edge, circles, squares, realistic ice floe field) were modelled. Simulations show that Δ L increases by the radius of the ice floe and for sizes larger than 6 km (500-1000 m <span class="hlt">cloud</span> altitude) asymptotically reaches maximum values, which corresponds to an infinite straight ice edge. Furthermore, the impact of these 3-D-radiative effects on retrieval of <span class="hlt">cloud</span> optical properties was investigated. The enhanced brightness of a dark pixel next to an ice edge results in uncertainties of up to 90 and 30% in retrievals of <span class="hlt">cloud</span> optical thickness and effective radius reff, respectively. With help of Δ L quantified here, an</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/1252820-wind-speed-response-marine-non-precipitating-stratocumulus-clouds-over-diurnal-cycle-cloud-system-resolving-simulations','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/1252820-wind-speed-response-marine-non-precipitating-stratocumulus-clouds-over-diurnal-cycle-cloud-system-resolving-simulations"><span>Wind speed response of marine non-precipitating stratocumulus <span class="hlt">clouds</span> over a diurnal cycle in <span class="hlt">cloud</span>-system resolving simulations</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kazil, Jan; Feingold, Graham; Yamaguchi, Takanobu</p> <p></p> <p>Observed and projected trends in large-scale wind speed over the oceans prompt the question: how do marine stratocumulus <span class="hlt">clouds</span> and their radiative properties respond to changes in large-scale wind speed? Wind speed drives the surface fluxes of sensible heat, moisture, and momentum and thereby acts on <span class="hlt">cloud</span> liquid water path (LWP) and <span class="hlt">cloud</span> radiative properties. We present an investigation of the dynamical response of non-precipitating, overcast marine stratocumulus <span class="hlt">clouds</span> to different wind speeds over the course of a diurnal cycle, all else equal. In <span class="hlt">cloud</span>-system resolving simulations, we find that higher wind speed leads to faster boundary <span class="hlt">layer</span> growth and strongermore » entrainment. The dynamical driver is enhanced buoyant production of turbulence kinetic energy (TKE) from latent heat release in <span class="hlt">cloud</span> updrafts. LWP is enhanced during the night and in the morning at higher wind speed, and more strongly suppressed later in the day. Wind speed hence accentuates the diurnal LWP cycle by expanding the morning–afternoon contrast. The higher LWP at higher wind speed does not, however, enhance <span class="hlt">cloud</span> top cooling because in <span class="hlt">clouds</span> with LWP ≳50 gm –2, longwave emissions are insensitive to LWP. This leads to the general conclusion that in sufficiently thick stratocumulus <span class="hlt">clouds</span>, additional boundary <span class="hlt">layer</span> growth and entrainment due to a boundary <span class="hlt">layer</span> moistening arises by stronger production of TKE from latent heat release in <span class="hlt">cloud</span> updrafts, rather than from enhanced longwave cooling. Here, we find that large-scale wind modulates boundary <span class="hlt">layer</span> decoupling. At nighttime and at low wind speed during daytime, it enhances decoupling in part by faster boundary <span class="hlt">layer</span> growth and stronger entrainment and in part because shear from large-scale wind in the sub-<span class="hlt">cloud</span> <span class="hlt">layer</span> hinders vertical moisture transport between the surface and <span class="hlt">cloud</span> base. With increasing wind speed, however, in decoupled daytime conditions, shear-driven circulation due to large-scale wind takes over from</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1252820-wind-speed-response-marine-non-precipitating-stratocumulus-clouds-over-diurnal-cycle-cloud-system-resolving-simulations','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1252820-wind-speed-response-marine-non-precipitating-stratocumulus-clouds-over-diurnal-cycle-cloud-system-resolving-simulations"><span>Wind speed response of marine non-precipitating stratocumulus <span class="hlt">clouds</span> over a diurnal cycle in <span class="hlt">cloud</span>-system resolving simulations</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Kazil, Jan; Feingold, Graham; Yamaguchi, Takanobu</p> <p>2016-05-12</p> <p>Observed and projected trends in large-scale wind speed over the oceans prompt the question: how do marine stratocumulus <span class="hlt">clouds</span> and their radiative properties respond to changes in large-scale wind speed? Wind speed drives the surface fluxes of sensible heat, moisture, and momentum and thereby acts on <span class="hlt">cloud</span> liquid water path (LWP) and <span class="hlt">cloud</span> radiative properties. We present an investigation of the dynamical response of non-precipitating, overcast marine stratocumulus <span class="hlt">clouds</span> to different wind speeds over the course of a diurnal cycle, all else equal. In <span class="hlt">cloud</span>-system resolving simulations, we find that higher wind speed leads to faster boundary <span class="hlt">layer</span> growth and strongermore » entrainment. The dynamical driver is enhanced buoyant production of turbulence kinetic energy (TKE) from latent heat release in <span class="hlt">cloud</span> updrafts. LWP is enhanced during the night and in the morning at higher wind speed, and more strongly suppressed later in the day. Wind speed hence accentuates the diurnal LWP cycle by expanding the morning–afternoon contrast. The higher LWP at higher wind speed does not, however, enhance <span class="hlt">cloud</span> top cooling because in <span class="hlt">clouds</span> with LWP ≳50 gm –2, longwave emissions are insensitive to LWP. This leads to the general conclusion that in sufficiently thick stratocumulus <span class="hlt">clouds</span>, additional boundary <span class="hlt">layer</span> growth and entrainment due to a boundary <span class="hlt">layer</span> moistening arises by stronger production of TKE from latent heat release in <span class="hlt">cloud</span> updrafts, rather than from enhanced longwave cooling. Here, we find that large-scale wind modulates boundary <span class="hlt">layer</span> decoupling. At nighttime and at low wind speed during daytime, it enhances decoupling in part by faster boundary <span class="hlt">layer</span> growth and stronger entrainment and in part because shear from large-scale wind in the sub-<span class="hlt">cloud</span> <span class="hlt">layer</span> hinders vertical moisture transport between the surface and <span class="hlt">cloud</span> base. With increasing wind speed, however, in decoupled daytime conditions, shear-driven circulation due to large-scale wind takes over from</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003JApMe..42.1720M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003JApMe..42.1720M"><span>Characterization of the <span class="hlt">Cloud</span>-Topped Boundary <span class="hlt">Layer</span> at the Synoptic Scale Using AVHRR Observations during the SEMAPHORE Experiment.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mathieu, A.; Sèze, G.; Lahellec, A.; Guerin, C.; Weill, A.</p> <p>2003-12-01</p> <p>Satellite platforms NOAA-11 and -12 Advanced Very High Resolution Radiometer (AVHRR) data are used during the daytime to study large sheets of stratocumulus over the North Atlantic Ocean. The application concerns an anticyclonic period of the Structure des Echanges Mer Atmosphère, Propriétés des Hétérogénéités Océaniques: Recherché Expérimentale (SEMAPHORE) campaign (10 17 November 1993). In the region of interest, the satellite images are recorded under large solar zenith angles. Extending the SEMAPHORE area, a region of about 3000 × 3000 km2 is studied to characterize the atmospheric boundary <span class="hlt">layer</span>. A statistical <span class="hlt">cloud</span> classification method is applied to discriminate for low-level and optically thick <span class="hlt">clouds</span>. For AVHRR pixels covered with thick <span class="hlt">clouds</span>, brightness temperatures are used to evaluate the boundary <span class="hlt">layer</span> <span class="hlt">cloud</span>-top temperature (CTT). The objective is to obtain accurate CTT maps for evaluation of a global model. In this application, the full-resolution fields are reduced to match model grid size. An estimate of overall temperature uncertainty associated with each grid point is also derived, which incorporates subgrid variability of the fields and quality of the temperature retrieval. Results are compared with the SEMAPHORE campaign measurements. A comparison with “DX” products obtained with the same dataset, but at lower resolution, is also presented. The authors claim that such instantaneous CTT maps could be as intensively used as classical SST maps, and both could be efficiently complemented with gridpoint error-bar maps. They may be used for multiple applications: (i) to provide a means to improve numerical weather prediction and climatological reanalyses, (ii) to represent a boundary <span class="hlt">layer</span> global characterization to analyze the synoptic situation of field experiments, and (iii) to allow validation and to test development of large-scale and mesoscale models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20160006617','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20160006617"><span>Comparison Between CCCM and <span class="hlt">Cloud</span>Sat Radar-Lidar (RL) <span class="hlt">Cloud</span> and Radiation Products</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ham, Seung-Hee; Kato, Seiji; Rose, Fred G.; Sun-Mack, Sunny</p> <p>2015-01-01</p> <p>To enhance <span class="hlt">cloud</span> properties, LaRC and CIRA developed each combination algorithm for obtained properties from passive, active and imager in A-satellite constellation. When comparing global <span class="hlt">cloud</span> fraction each other, LaRC-produced CERES-CALIPSO-<span class="hlt">Cloud</span>Sat-MODIS (CCCM) products larger low-level <span class="hlt">cloud</span> fraction over tropic ocean, while CIRA-produced Radar-Lidar (RL) shows larger mid-level <span class="hlt">cloud</span> fraction for high latitude region. The reason for different low-level <span class="hlt">cloud</span> fraction is due to different filtering method of lidar-detected <span class="hlt">cloud</span> <span class="hlt">layers</span>. Meanwhile difference in mid-level <span class="hlt">clouds</span> is occurred due to different priority of <span class="hlt">cloud</span> boundaries from lidar and radar.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19840049032&hterms=kinetic+energy&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dkinetic%2Benergy','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19840049032&hterms=kinetic+energy&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dkinetic%2Benergy"><span>Buoyant production and consumption of turbulence kinetic energy in <span class="hlt">cloud</span>-topped mixed <span class="hlt">layers</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Randall, D. A.</p> <p>1984-01-01</p> <p>It is pointed out that studies of the entraining planetary boundary <span class="hlt">layer</span> (PBL) have generally emphasized the role of buoyancy fluxes in driving entrainment. The buoyancy flux is proportional to the rate of conversion of the potential energy of the mean flow into the kinetic energy of the turbulence. It is not unusual for conversion to proceed in both directions simultaneously. This occurs, for instance, in both clear and cloudy convective mixed <span class="hlt">layers</span> which are capped by inversions. A partitioning of the net conversion into positive parts, generating turbulence kinetic energy (TKE), and negative parts (TKE-consuming), would make it possible to include the positive part in the gross production rate, and closure would be achieved. Three different approaches to partitioning have been proposed. The present investigation is concerned with a comparison of the three partitioning theories. Particular attention is given to the <span class="hlt">cloud</span>-topped mixed <span class="hlt">layer</span> because in this case the differences between two partitioning approaches are most apparent.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120009850','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120009850"><span>A Study of Global Cirrus <span class="hlt">Cloud</span> Morphology with AIRS <span class="hlt">Cloud</span>-clear Radiances (CCRs)</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wu, Dong L.; Gong, Jie</p> <p>2012-01-01</p> <p>Version 6 (V6) AIRS <span class="hlt">cloud</span>-clear radiances (CCR) are used to derive <span class="hlt">cloud</span>-induced radiance (Tcir=Tb-CCR) at the infrared frequencies of weighting functions peaked in the <span class="hlt">middle</span> troposphere. The significantly improved V 6 CCR product allows a more accurate estimation of the expected clear-sky radiance as if <span class="hlt">clouds</span> are absent. In the case where strong <span class="hlt">cloud</span> scattering is present, the CCR becomes unreliable, which is reflected by its estimated uncertainty, and interpolation is employed to replace this CCR value. We find that Tcir derived from this CCR method are much better than other methods and detect more <span class="hlt">clouds</span> in the upper and lower troposphere as well as in the polar regions where <span class="hlt">cloud</span> detection is particularly challenging. The <span class="hlt">cloud</span> morphology derived from the V6 test month, as well as some artifacts, will be shown.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017Icar..286..134K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017Icar..286..134K"><span>On the iron chloride aerosol in the <span class="hlt">clouds</span> of Venus</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Krasnopolsky, Vladimir A.</p> <p>2017-04-01</p> <p>Iron chloride in the Venus <span class="hlt">clouds</span> is under discussion for three decades, and the saturated vapor pressure of this species is of crucial importance for its modeling. There is a great scatter in the published data, and the preferable results are by Rustad and Gregory (1983, J. Chem. Eng. Data 28, 151-155) and those based on thermodynamic parameters by Chase (1998, J. Phys. Chem. Ref. Data Monograph 9). Using these data, loss by coagulation with sulfuric acid, transport by eddy diffusion, and the Stokes precipitation, the model confirms conclusions of our early study (Krasnopolsky 1985, Planet. Space Sci. 33, 109-117) that FeCl3 in the Venus <span class="hlt">clouds</span> (1) agrees with the near UV and blue reflectivity of Venus (Zasova et al. 1981, Adv. Space Res. 1, #9, 13-16), (2) was observed by the direct X-ray fluorescent spectroscopy, (3) explains the altitude profiles of the mode 1 aerosol in the <span class="hlt">middle</span> and lower <span class="hlt">cloud</span> <span class="hlt">layers</span> and (4) the decrease in the NUV absorption below 60 km. Here we add to these conclusions that (5) the delivery of FeCl3 into the upper <span class="hlt">cloud</span> <span class="hlt">layer</span> and the production of sulfuric acid are just in proportion of 1: 100 by mass that is required to fit the observed NUV albedo. Furthermore, (6) the mode 1 and 2 particle sizes fit this proportion as well. Finally, (7) the required Fe2Cl6 mixing ratio is 17 ppbv in the atmosphere and the FeCl3 mole fraction is 19 ppbv in the Venus surface rocks.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20000031600&hterms=Property+Types&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DProperty%2BTypes','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20000031600&hterms=Property+Types&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DProperty%2BTypes"><span>ISCCP <span class="hlt">Cloud</span> Properties Associated with Standard <span class="hlt">Cloud</span> Types Identified in Individual Surface Observations</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hahn, Carole J.; Rossow, William B.; Warren, Stephen G.</p> <p>1999-01-01</p> <p>Individual surface weather observations from land stations and ships are compared with individual <span class="hlt">cloud</span> retrievals of the International Satellite <span class="hlt">Cloud</span> Climatology Project (ISCCP), Stage C1, for an 8-year period (1983-1991) to relate <span class="hlt">cloud</span> optical thicknesses and <span class="hlt">cloud</span>-top pressures obtained from satellite data to the standard <span class="hlt">cloud</span> 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 <span class="hlt">cloud</span> type was reported present, either alone or in combination with other <span class="hlt">clouds</span>. For each class, <span class="hlt">cloud</span> amounts from both surface and C1 data, base heights from surface data, and the frequency-distributions of <span class="hlt">cloud</span>-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 <span class="hlt">cloud</span> types occurring both alone and with other <span class="hlt">clouds</span>. The average <span class="hlt">cloud</span>-top pressures within a grid-box do not always correspond well with values expected for a reported <span class="hlt">cloud</span> type, particularly for the higher <span class="hlt">clouds</span> Ci, Ac, and Cb. In many cases this is because the satellites also detect <span class="hlt">clouds</span> within the grid-box that are outside the field of view of the surface observer. The highest average <span class="hlt">cloud</span> tops are found for the most extensive <span class="hlt">cloud</span> 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 <span class="hlt">clouds</span> 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, <span class="hlt">middle</span>, and low <span class="hlt">clouds</span> reported by the surface observers. However, the distribution patterns for the individual low <span class="hlt">cloud</span> types (Cu, Sc, St</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20130014863','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20130014863"><span>A FIRE-ACE/SHEBA Case Study of Mixed-Phase Arctic Boundary <span class="hlt">Layer</span> <span class="hlt">Clouds</span>: Entrainment Rate Limitations on Rapid Primary Ice Nucleation Processes</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Fridlin, Ann; vanDiedenhoven, Bastiaan; Ackerman, Andrew S.; Avramov, Alexander; Mrowiec, Agnieszka; Morrison, Hugh; Zuidema, Paquita; Shupe, Matthew D.</p> <p>2012-01-01</p> <p>Observations of long-lived mixed-phase Arctic boundary <span class="hlt">layer</span> <span class="hlt">clouds</span> on 7 May 1998 during the First International Satellite <span class="hlt">Cloud</span> Climatology Project (ISCCP) Regional Experiment (FIRE)Arctic <span class="hlt">Cloud</span> Experiment (ACE)Surface Heat Budget of the Arctic Ocean (SHEBA) campaign provide a unique opportunity to test understanding of <span class="hlt">cloud</span> ice formation. Under the microphysically simple conditions observed (apparently negligible ice aggregation, sublimation, and multiplication), the only expected source of new ice crystals is activation of heterogeneous ice nuclei (IN) and the only sink is sedimentation. Large-eddy simulations with size-resolved microphysics are initialized with IN number concentration N(sub IN) measured above <span class="hlt">cloud</span> top, but details of IN activation behavior are unknown. If activated rapidly (in deposition, condensation, or immersion modes), as commonly assumed, IN are depleted from the well-mixed boundary <span class="hlt">layer</span> within minutes. Quasi-equilibrium ice number concentration N(sub i) is then limited to a small fraction of overlying N(sub IN) that is determined by the <span class="hlt">cloud</span>-top entrainment rate w(sub e) divided by the number-weighted ice fall speed at the surface v(sub f). Because w(sub c)< 1 cm/s and v(sub f)> 10 cm/s, N(sub i)/N(sub IN)<< 1. Such conditions may be common for this <span class="hlt">cloud</span> type, which has implications for modeling IN diagnostically, interpreting measurements, and quantifying sensitivity to increasing N(sub IN) (when w(sub e)/v(sub f)< 1, entrainment rate limitations serve to buffer <span class="hlt">cloud</span> system response). To reproduce observed ice crystal size distributions and <span class="hlt">cloud</span> radar reflectivities with rapidly consumed IN in this case, the measured above-<span class="hlt">cloud</span> N(sub IN) must be multiplied by approximately 30. However, results are sensitive to assumed ice crystal properties not constrained by measurements. In addition, simulations do not reproduce the pronounced mesoscale heterogeneity in radar reflectivity that is observed.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_10 --> <div id="page_11" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="201"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18324021','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18324021"><span>Influence of daylight and noise current on <span class="hlt">cloud</span> and aerosol observations by spaceborne elastic scattering lidar.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nakajima, T Y; Imai, T; Uchino, O; Nagai, T</p> <p>1999-08-20</p> <p>The influence of daylight and noise current on <span class="hlt">cloud</span> and aerosol observations by realistic spaceborne lidar was examined by computer simulations. The reflected solar radiations, which contaminate the daytime return signals of lidar operations, were strictly and explicitly estimated by accurate radiative transfer calculations. It was found that the model multilayer cirrus <span class="hlt">clouds</span> and the boundary <span class="hlt">layer</span> aerosols could be observed during the daytime and the nighttime with only a few laser shots. However, high background noise and noise current make it difficult to observe volcanic aerosols in <span class="hlt">middle</span> and upper atmospheric <span class="hlt">layers</span>. Optimal combinations of the laser power and receiver field of view are proposed to compensate for the negative influence that is due to these noises. For the computer simulations, we used a realistic set of lidar parameters similar to the Experimental Lidar in-Space Equipment of the National Space Development Agency of Japan.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20080006490','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20080006490"><span>A Fast Infrared Radiative Transfer Model for Overlapping <span class="hlt">Clouds</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Niu, Jianguo; Yang, Ping; Huang, Huang-Lung; Davies, James E.; Li, Jun; Baum, Bryan A.; Hu, Yong X.</p> <p>2006-01-01</p> <p>A fast infrared radiative transfer model (FIRTM2) appropriate for application to both single-<span class="hlt">layered</span> and overlapping <span class="hlt">cloud</span> situations is developed for simulating the outgoing infrared spectral radiance at the top of the atmosphere (TOA). In FIRTM2 a pre-computed library of <span class="hlt">cloud</span> reflectance and transmittance values is employed to account for one or two <span class="hlt">cloud</span> <span class="hlt">layers</span>, whereas the background atmospheric optical thickness due to gaseous absorption can be computed from a clear-sky radiative transfer model. FIRTM2 is applicable to three atmospheric conditions: 1) clear-sky, 2) single-<span class="hlt">layered</span> ice or water <span class="hlt">cloud</span>, and 3) two simultaneous <span class="hlt">cloud</span> <span class="hlt">layers</span> in a column (e.g., ice <span class="hlt">cloud</span> overlying water <span class="hlt">cloud</span>). Moreover, FIRTM2 outputs the derivatives (i.e., Jacobians) of the TOA brightness temperature with respect to <span class="hlt">cloud</span> optical thickness and effective particle size. Sensitivity analyses have been carried out to assess the performance of FIRTM2 for two spectral regions, namely the longwave (LW) band (587.3 - 1179.5/cm) and the short-to-medium wave (SMW) band (1180.1 - 2228.9/cm). The assessment is carried out in terms of brightness temperature differences (BTD) between FIRTM2 and the well-known discrete ordinates radiative transfer model (DISORT), henceforth referred to as BTD (F-D). The BTD (F-D) values for single-<span class="hlt">layered</span> <span class="hlt">clouds</span> are generally less than 0.8 K. For the case of two <span class="hlt">cloud</span> <span class="hlt">layers</span> (specifically ice <span class="hlt">cloud</span> over water <span class="hlt">cloud</span>), the BTD(F-D) values are also generally less than 0.8 K except for the SMW band for the case of a very high altitude (>15 km) <span class="hlt">cloud</span> comprised of small ice particles. Note that for clear-sky atmospheres, FIRTM2 reduces to the clear-sky radiative transfer model that is incorporated into FIRTM2, and the errors in this case are essentially those of the clear-sky radiative transfer model.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.A23P..03D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.A23P..03D"><span>Comparison of Marine Boundary <span class="hlt">Layer</span> <span class="hlt">Cloud</span> Properties From CERES-MODIS Edition 4 and DOE ARM AMF Measurements at the Azores</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dong, X.; Xi, B.; Minnis, P.; Sun-Mack, S.</p> <p>2014-12-01</p> <p>Marine Boundary <span class="hlt">Layer</span> (MBL) <span class="hlt">cloud</span> properties derived for the NASA CERES Project using Terra and Aqua MODIS data are compared with observations taken at DOE ARM Mobile Facility at the Azores site from Jun. 2009 to Dec. 2010. <span class="hlt">Cloud</span> properties derived from ARM ground-based observations were averaged over a 1-hour interval centered at the satellite overpass time, while the CERES-MODIS (CM) results were averaged within a 30×30 km2 grid box centered over the Azores site. A total of 63 daytime and 92 nighttime single-<span class="hlt">layered</span> overcast MBL <span class="hlt">cloud</span> cases were selected from 19 months of ARM radar-lidar and satellite observations. The CM <span class="hlt">cloud</span>-top/base heights (Htop/Hbase) were determined from <span class="hlt">cloud</span>-top/base temperatures (Ttop/Tbase) using a regional boundary-<span class="hlt">layer</span> lapse rate method. For daytime comparisons, the CM-derived Htop (Hbase), on average, is 0.063 km (0.068 km) higher (lower) than its ARM radar-lidar observed counterpart, and the CM-derived Ttop and Tbase are 0.9 K less and 2.5 K greater than the surface values with high correlations (R2=0.82 and 0.84, respectively). In general, the <span class="hlt">cloud</span>-top comparisons agree better than <span class="hlt">cloud</span>-base comparisons because the CM Tbase and Hbase are secondary product determined from Ttop and Htop. No significant day-night difference was found in the analyses. The comparisons of microphysical properties reveal that, when averaged over a 30x30 km2 area, the CM-retrieved <span class="hlt">cloud</span>-droplet effective radius (re) is 1.3 µm larger than that from the ARM retrievals (12.8 µm). While the CM-retrieved <span class="hlt">cloud</span> liquid water path (LWP) is 13.5 gm-2 less than its ARM counterpart (114.2 gm-2) due to its small optical depth (τ, 9.6 vs. 13.7). The differences are reduced by 50% when the CM averages are computed only using the MODIS pixel nearest the AMF site. Using effective radius retrieved at 2.1-µm channel to calculate LWP can reduce the difference between the CM and ARM from -13.7 to 2.1 gm-2. The 10% differences between the ARM and CM LWP and re</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/1430421-evaluation-marine-boundary-layer-cloud-property-simulations-community-atmosphere-model-using-satellite-observations-conventional-subgrid-parameterization-versus-clubb','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/1430421-evaluation-marine-boundary-layer-cloud-property-simulations-community-atmosphere-model-using-satellite-observations-conventional-subgrid-parameterization-versus-clubb"><span>An Evaluation of Marine Boundary <span class="hlt">Layer</span> <span class="hlt">Cloud</span> Property Simulations in the Community Atmosphere Model Using Satellite Observations: Conventional Subgrid Parameterization versus CLUBB</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Song, Hua; Zhang, Zhibo; Ma, Po-Lun</p> <p></p> <p>This paper presents a two-step evaluation of the marine boundary <span class="hlt">layer</span> (MBL) <span class="hlt">cloud</span> properties from two Community Atmospheric Model (version 5.3, CAM5) simulations, one based on the CAM5 standard parameterization schemes (CAM5-Base), and the other on the <span class="hlt">Cloud</span> <span class="hlt">Layers</span> Unified By Binormals (CLUBB) scheme (CAM5-CLUBB). In the first step, we compare the <span class="hlt">cloud</span> properties directly from model outputs between the two simulations. We find that the CAM5-CLUBB run produces more MBL <span class="hlt">clouds</span> in the tropical and subtropical large-scale descending regions. Moreover, the stratocumulus (Sc) to cumulus (Cu) <span class="hlt">cloud</span> regime transition is much smoother in CAM5-CLUBB than in CAM5-Base. In addition,more » in CAM5-Base we find some grid cells with very small low <span class="hlt">cloud</span> fraction (<20%) to have very high in-<span class="hlt">cloud</span> water content (mixing ratio up to 400mg/kg). We find no such grid cells in the CAM5-CLUBB run. However, we also note that both simulations, especially CAM5-CLUBB, produce a significant amount of “empty” low <span class="hlt">cloud</span> cells with significant <span class="hlt">cloud</span> fraction (up to 70%) and near-zero in-<span class="hlt">cloud</span> water content. In the second step, we use satellite observations from CERES, MODIS and <span class="hlt">Cloud</span>Sat to evaluate the simulated MBL <span class="hlt">cloud</span> properties by employing the COSP satellite simulators. We note that a feature of the COSP-MODIS simulator to mimic the minimum detection threshold of MODIS <span class="hlt">cloud</span> masking removes much more low <span class="hlt">clouds</span> from CAM5-CLUBB than it does from CAM5-Base. This leads to a surprising result — in the large-scale descending regions CAM5-CLUBB has a smaller COSP-MODIS <span class="hlt">cloud</span> fraction and weaker shortwave <span class="hlt">cloud</span> radiative forcing than CAM5-Base. A sensitivity study suggests that this is because CAM5-CLUBB suffers more from the above-mentioned “empty” <span class="hlt">clouds</span> issue than CAM5-Base. The COSP-MODIS <span class="hlt">cloud</span> droplet effective radius in CAM5-CLUBB shows a spatial increase from coastal St toward Cu, which is in qualitative agreement with MODIS observations. In contrast, COSP-MODIS <span class="hlt">cloud</span> droplet</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018AIPC.1952b0045K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018AIPC.1952b0045K"><span>Assessment of physical server reliability in multi <span class="hlt">cloud</span> computing system</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kalyani, B. J. D.; Rao, Kolasani Ramchand H.</p> <p>2018-04-01</p> <p>Business organizations nowadays functioning with more than one <span class="hlt">cloud</span> provider. By spreading <span class="hlt">cloud</span> deployment across multiple service providers, it creates space for competitive prices that minimize the burden on enterprises spending budget. To assess the software reliability of multi <span class="hlt">cloud</span> application <span class="hlt">layered</span> software reliability assessment paradigm is considered with three levels of abstractions application <span class="hlt">layer</span>, virtualization <span class="hlt">layer</span>, and server <span class="hlt">layer</span>. The reliability of each <span class="hlt">layer</span> is assessed separately and is combined to get the reliability of multi-<span class="hlt">cloud</span> computing application. In this paper, we focused on how to assess the reliability of server <span class="hlt">layer</span> with required algorithms and explore the steps in the assessment of server reliability.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150000361','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150000361"><span>Global Free-tropospheric NO2 Abundances Derived Using a <span class="hlt">Cloud</span> Slicing Technique from AURA OMI</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Choi, S.; Joiner, J.; Choi, Y.; Duncan, B.N.; Vasilkov, A.; Krotkov, N.; Bucsela, E.J.</p> <p>2014-01-01</p> <p>We derive free-tropospheric NO2 volume mixing ratios (VMRs) by applying a <span class="hlt">cloud</span>-slicing technique to data from the Ozone Monitoring Instrument (OMI) on the Aura satellite. In the <span class="hlt">cloud</span>-slicing approach, the slope of the above-<span class="hlt">cloud</span> NO2 column versus the <span class="hlt">cloud</span> scene pressure is proportional to the NO2 VMR. In this work, we use a sample of nearby OMI pixel data from a single orbit for the linear fit. The OMI data include <span class="hlt">cloud</span> scene pressures from the rotational-Raman algorithm and above-<span class="hlt">cloud</span> NO2 vertical column density (VCD) (defined as the NO2 column from the <span class="hlt">cloud</span> scene pressure to the top of the atmosphere) from a differential optical absorption spectroscopy (DOAS) algorithm. We compare OMI-derived NO2 VMRs with in situ aircraft profiles measured during the NASA Intercontinental Chemical Transport Experiment Phase B (INTEX-B) campaign in 2006. The agreement is generally within the estimated uncertainties when appropriate data screening is applied. We then derive a global seasonal climatology of free-tropospheric NO2 VMR in cloudy conditions. Enhanced NO2 in the free troposphere commonly appears near polluted urban locations where NO2 produced in the boundary <span class="hlt">layer</span> may be transported vertically out of the boundary <span class="hlt">layer</span> and then horizontally away from the source. Signatures of lightning NO2 are also shown throughout low and <span class="hlt">middle</span> latitude regions in summer months. A profile analysis of our <span class="hlt">cloud</span>-slicing data indicates signatures of lightning-generated NO2 in the upper troposphere. Comparison of the climatology with simulations from the global modeling initiative (GMI) for cloudy conditions (<span class="hlt">cloud</span> optical depth less than10) shows similarities in the spatial patterns of continental pollution outflow. However, there are also some differences in the seasonal variation of free-tropospheric NO2 VMRs near highly populated regions and in areas affected by lightning-generated NOx.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011ACPD...1115417Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011ACPD...1115417Z"><span>Observations of the boundary <span class="hlt">layer</span>, <span class="hlt">cloud</span>, and aerosol variability in the southeast Pacific coastal marine stratocumulus during VOCALS-REx</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zheng, X.; Albrecht, B.; Jonsson, H. H.; Khelif, D.; Feingold, G.; Minnis, P.; Ayers, K.; Chuang, P.; Donaher, S.; Rossiter, D.; Ghate, V.; Ruiz-Plancarte, J.; Sun-Mack, S.</p> <p>2011-05-01</p> <p>Aircraft observations made off the coast of northern Chile in the Southeastern Pacific (20° S, 72° W; named Point Alpha) from 16 October to 13 November 2008 during the VAMOS Ocean-<span class="hlt">Cloud</span>-Atmosphere-Land Study-Regional Experiment (VOCALS-REx), combined with meteorological reanalysis, satellite measurements, and radiosonde data, are used to investigate the boundary <span class="hlt">layer</span> (BL) and aerosol-<span class="hlt">cloud</span>-drizzle variations in this region. The BL at Point Alpha was typical of a non-drizzling stratocumulus-topped BL on days without predominately synoptic and meso-scale influences. The BL had a depth of 1140 ± 120 m, was well-mixed and capped by a sharp inversion. The wind direction generally switched from southerly within the BL to northerly above the inversion. The <span class="hlt">cloud</span> liquid water path (LWP) varied between 15 g m-2 and 160 g m-2. From 29 October to 4 November, when a synoptic system affected conditions at Point Alpha, the <span class="hlt">cloud</span> LWP was higher than on the other days by around 40 g m-2. On 1 and 2 November, a moist <span class="hlt">layer</span> above the inversion moved over Point Alpha. The total-water specific humidity above the inversion was larger than that within the BL during these days. Entrainment rates (average of 1.5 ± 0.6 mm s-1) calculated from the near <span class="hlt">cloud</span>-top fluxes and turbulence (vertical velocity variance) in the BL at Point Alpha appeared to be weaker than those in the BL over the open ocean west of Point Alpha and the BL near the coast of the northeast Pacific. The accumulation mode aerosol varied from 250 to 700 cm-3 within the BL, and CCN at 0.2 % supersaturation within the BL ranged between 150 and 550 cm-3. The main aerosol source at Point Alpha was horizontal advection within the BL from south. The average <span class="hlt">cloud</span> droplet number concentration ranged between 80 and 400 cm-3, which was consistent with the satellite-derived values. The relationship of <span class="hlt">cloud</span> droplet number concentration and CCN at 0.2 % supersaturation from 18 flights is Nd =4.6 × CCN0.71. While the mean LWP</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA04329.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA04329.html"><span>Multi-<span class="hlt">layer</span> <span class="hlt">Clouds</span> Over the South Indian Ocean</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2003-05-07</p> <p>The complex structure and beauty of polar <span class="hlt">clouds</span> are highlighted by these images acquired by NASA Terra spacecraft on April 23, 2003. These <span class="hlt">clouds</span> occur at multiple altitudes and exhibit a noticeable cyclonic circulation over the Southern Indian Ocean,</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19830056199&hterms=ia&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dia','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19830056199&hterms=ia&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dia"><span>The <span class="hlt">clouds</span> are hazes of Venus</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Esposito, L. W.; Knollenberg, R. G.; Marov, M. IA.; Toon, O. B.; Turco, R. P.</p> <p>1983-01-01</p> <p>Pioneer Venus and Venera probe data for the <span class="hlt">clouds</span> of Venus are considered. These <span class="hlt">clouds</span> consist of a main <span class="hlt">cloud</span> deck at 45-70 km altitude, with thinner hazes above and below, although the microphysical properties of the main <span class="hlt">cloud</span> are further subdivided into upper, <span class="hlt">middle</span> and lower <span class="hlt">cloud</span> levels. Much of the <span class="hlt">cloud</span> 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 <span class="hlt">clouds</span> indicates persistent features at sites separated by years and by great distances. The <span class="hlt">clouds</span> 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 <span class="hlt">cloud</span> origin.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA01459&hterms=mass+wasting&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dmass%2Bwasting','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA01459&hterms=mass+wasting&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dmass%2Bwasting"><span>Western Candor Chasma - <span class="hlt">Layers</span> exposed near the <span class="hlt">middle</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1998-01-01</p> <p> potential to reveal information about the early history and evolution of the red planet. The MOC Science Team is continuing to examine the wealth of new data and planning for new Valles Marineris targets once the Mapping Phase of the Mars Global Surveyor mission commences in March 1999.<p/><span class="hlt">Layers</span> exposed near the <span class="hlt">middle</span> of western Candor Chasma. MOC image 23304 subframe shown at 10.7 meters (35 feet) per pixel. Two <span class="hlt">layered</span> buttes (upper right and lower right) and a <span class="hlt">layered</span> or stepped mesa (center right) are shown. The image covers an area approximately 5.5 by 5.5 kilometers (3.4 x 3.4 miles). North is approximately up, illumination is from the lower right. Image 23304 was obtained during Mars Global Surveyor's 233rd orbit at 9:23 a.m. (PDT) on April 11, 1998.<p/>Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19850003614','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19850003614"><span><span class="hlt">Clouds</span> above the Martin Limb: Viking observations</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Martin, L. J.; Baum, W. A.; Wasserman, L. H.; Kreidl, T. J.</p> <p>1984-01-01</p> <p>Whenever Viking Orbiter images included the limb of Mars, they recorded one or more <span class="hlt">layers</span> of <span class="hlt">clouds</span> above the limb. The height above the limb and the brightness (reflectivity) of these <span class="hlt">clouds</span> were determined in a selected group of these images. Normalized individual brightness profiles of three separate traverses across the limb of each image are shown. The most notable finding is that some of these <span class="hlt">clouds</span> can be very high. Many reach heights of over 60 km, and several are over 70 km above the limb. Statistically, the reflectivity of the <span class="hlt">clouds</span> increases with phase angle. Reflectivity and height both appear to vary with season, but the selected images spanned only one Martian year, so the role of seasons cannot be isolated. Limb <span class="hlt">clouds</span> in red-filter images tend to be brighter than violet-filter images, but both season and phase appear to be more dominant factors. Due to the limited sample available, the possible influences of latitude and longitude are less clear. The <span class="hlt">layering</span> of these <span class="hlt">clouds</span> ranges from a single <span class="hlt">layer</span> to five or more <span class="hlt">layers</span>. Reflectivity gradients range from smooth and gentle to steep and irregular.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20080000873&hterms=Geostationary&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DGeostationary','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20080000873&hterms=Geostationary&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DGeostationary"><span>Comparison of <span class="hlt">Cloud</span> Properties from CALIPSO-<span class="hlt">Cloud</span>Sat and Geostationary Satellite Data</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Nguyen, L.; Minnis, P.; Chang, F.; Winker, D.; Sun-Mack, S.; Spangenberg, D.; Austin, R.</p> <p>2007-01-01</p> <p><span class="hlt">Cloud</span> properties are being derived in near-real time from geostationary satellite imager data for a variety of weather and climate applications and research. Assessment of the uncertainties in each of the derived <span class="hlt">cloud</span> parameters is essential for confident use of the products. Determination of <span class="hlt">cloud</span> amount, <span class="hlt">cloud</span> top height, and <span class="hlt">cloud</span> <span class="hlt">layering</span> is especially important for using these real -time products for applications such as aircraft icing condition diagnosis and numerical weather prediction model assimilation. Furthermore, the distribution of <span class="hlt">clouds</span> as a function of altitude has become a central component of efforts to evaluate climate model <span class="hlt">cloud</span> simulations. Validation of those parameters has been difficult except over limited areas where ground-based active sensors, such as <span class="hlt">cloud</span> radars or lidars, have been available on a regular basis. Retrievals of <span class="hlt">cloud</span> properties are sensitive to the surface background, time of day, and the <span class="hlt">clouds</span> themselves. Thus, it is essential to assess the geostationary satellite retrievals over a variety of locations. The availability of <span class="hlt">cloud</span> radar data from <span class="hlt">Cloud</span>Sat and lidar data from CALIPSO make it possible to perform those assessments over each geostationary domain at 0130 and 1330 LT. In this paper, <span class="hlt">Cloud</span>Sat and CALIPSO data are matched with contemporaneous Geostationary Operational Environmental Satellite (GOES), Multi-functional Transport Satellite (MTSAT), and Meteosat-8 data. Unlike comparisons with <span class="hlt">cloud</span> products derived from A-Train imagers, this study considers comparisons of nadir active sensor data with off-nadir retrievals. These matched data are used to determine the uncertainties in <span class="hlt">cloud</span>-top heights and <span class="hlt">cloud</span> amounts derived from the geostationary satellite data using the <span class="hlt">Clouds</span> and the Earth s Radiant Energy System (CERES) <span class="hlt">cloud</span> retrieval algorithms. The CERES multi-<span class="hlt">layer</span> <span class="hlt">cloud</span> detection method is also evaluated to determine its accuracy and limitations in the off-nadir mode. The results will be useful for</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.A34E..05K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.A34E..05K"><span>Exploiting <span class="hlt">Cloud</span> Radar Doppler Spectra of Mixed-Phase <span class="hlt">Clouds</span> during ACCEPT Field Experiment to Identify Microphysical Processes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kalesse, H.; Myagkov, A.; Seifert, P.; Buehl, J.</p> <p>2015-12-01</p> <p><span class="hlt">Cloud</span> radar Doppler spectra offer much information about <span class="hlt">cloud</span> processes. By analyzing millimeter radar Doppler spectra from <span class="hlt">cloud</span>-top to -base in mixed-phase <span class="hlt">clouds</span> in which super-cooled liquid-<span class="hlt">layers</span> are present we try to tell the microphysical evolution story of particles that are present by disentangling the contributions of the solid and liquid particles to the total radar returns. Instead of considering vertical profiles, dynamical effects are taken into account by following the particle population evolution along slanted paths which are caused by horizontal advection of the <span class="hlt">cloud</span>. The goal is to identify regions in which different microphysical processes such as new particle formation (nucleation), water vapor deposition, aggregation, riming, or sublimation occurr. <span class="hlt">Cloud</span> radar measurements are supplemented by Doppler lidar and Raman lidar observations as well as observations with MWR, wind profiler, and radio sondes. The presence of super-cooled liquid <span class="hlt">layers</span> is identified by positive liquid water paths in MWR measurements, the vertical location of liquid <span class="hlt">layers</span> (in non-raining systems and below lidar extinction) is derived from regions of high-backscatter and low depolarization in Raman lidar observations. In collocated <span class="hlt">cloud</span> radar measurements, we try to identify <span class="hlt">cloud</span> phase in the <span class="hlt">cloud</span> radar Doppler spectrum via location of the Doppler peak(s), the existence of multi-modalities or the spectral skewness. Additionally, within the super-cooled liquid <span class="hlt">layers</span>, the radar-identified liquid droplets are used as air motion tracer to correct the radar Doppler spectrum for vertical air motion w. These radar-derived estimates of w are validated by independent estimates of w from collocated Doppler lidar measurements. A 35 GHz vertically pointing <span class="hlt">cloud</span> Doppler radar (METEK MIRA-35) in linear depolarization (LDR) mode is used. Data is from the deployment of the Leipzig Aerosol and <span class="hlt">Cloud</span> Remote Observations System (LACROS) during the Analysis of the Composition of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/7207256-airship-measurements-aerosol-size-distributions-cloud-droplet-spectra-trace-gas-concentrations-marine-boundary-layers','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/7207256-airship-measurements-aerosol-size-distributions-cloud-droplet-spectra-trace-gas-concentrations-marine-boundary-layers"><span>Airship measurements of aerosol size distributions, <span class="hlt">cloud</span> droplet spectra, and trace gas concentrations in the marine boundary <span class="hlt">layers</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Frick, G.M.; Hoppel, W.A.</p> <p>1993-11-01</p> <p>The use of an airship as a platform to conduct atmospheric chemistry, aerosol, and <span class="hlt">cloud</span> microphysical research is described, and results from demonstration flights made off the Oregon coast are presented. The slow speed of the airship makes it an ideal platform to do high-spatial resolution profiling both vertically and horizontally, and to measure large aerosol and <span class="hlt">cloud</span> droplet distributions without the difficulties caused by high-speed aircraft sampling. A unique set of data obtained during the demonstration flights show the effect that processing marine boundary <span class="hlt">layer</span> aerosol through stratus <span class="hlt">clouds</span> has on the aerosol size distribution. Evidence of new particlemore » formation (nucleation of particles) was also observed on about half the days on which flights were made. 11 refs., 9 figs., 1 tab.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20170001667','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20170001667"><span>First Transmitted Hyperspectral Light Measurements and <span class="hlt">Cloud</span> Properties from Recent Field Campaign Sampling <span class="hlt">Clouds</span> Under Biomass Burning Aerosol</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Leblanc, S.; Redemann, Jens; Shinozuka, Yohei; Flynn, Connor J.; Segal Rozenhaimer, Michal; Kacenelenbogen, Meloe Shenandoah; Pistone, Kristina Marie Myers; Schmidt, Sebastian; Cochrane, Sabrina</p> <p>2016-01-01</p> <p>We present a first view of data collected during a recent field campaign aimed at measuring biomass burning aerosol above <span class="hlt">clouds</span> from airborne platforms. The NASA ObseRvations of <span class="hlt">CLouds</span> above Aerosols and their intEractionS (ORACLES) field campaign recently concluded its first deployment sampling <span class="hlt">clouds</span> and overlying aerosol <span class="hlt">layer</span> 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 <span class="hlt">cloud</span> properties. We focus on the zenith-viewing scattered light measurements, which are used to retrieve <span class="hlt">cloud</span> optical thickness, effective radius, and thermodynamic phase of <span class="hlt">clouds</span> under a biomass burning <span class="hlt">layer</span>. The biomass burning aerosol <span class="hlt">layer</span> present above the <span class="hlt">clouds</span> is the cause of potential bias in retrieved <span class="hlt">cloud</span> 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 <span class="hlt">cloud</span> properties. It is suspected that these differing approaches will yield a change in retrieved properties since light transmitted through <span class="hlt">clouds</span> is sensitive to a different <span class="hlt">cloud</span> volume than reflected light at <span class="hlt">cloud</span> top. We offer a preliminary view of the implications of these differences in sampling volumes to the calculation of <span class="hlt">cloud</span> radiative effects (CRE).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1233295','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1233295"><span>Vertical microphysical profiles of convective <span class="hlt">clouds</span> as a tool for obtaining aerosol <span class="hlt">cloud</span>-mediated climate forcings</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Rosenfeld, Daniel</p> <p></p> <p>Quantifying the aerosol/<span class="hlt">cloud</span>-mediated radiative effect at a global scale requires simultaneous satellite retrievals of <span class="hlt">cloud</span> condensation nuclei (CCN) concentrations and <span class="hlt">cloud</span> base updraft velocities (Wb). Hitherto, the inability to do so has been a major cause of high uncertainty regarding anthropogenic aerosol/<span class="hlt">cloud</span>-mediated radiative forcing. This can be addressed by the emerging capability of estimating CCN and Wb of boundary <span class="hlt">layer</span> convective <span class="hlt">clouds</span> from an operational polar orbiting weather satellite. Our methodology uses such <span class="hlt">clouds</span> as an effective analog for CCN chambers. The <span class="hlt">cloud</span> base supersaturation (S) is determined by Wb and the satellite-retrieved <span class="hlt">cloud</span> base drop concentrations (Ndb), which ismore » the same as CCN(S). Developing and validating this methodology was possible thanks to the ASR/ARM measurements of CCN and vertical updraft profiles. Validation against ground-based CCN instruments at the ARM sites in Oklahoma, Manaus, and onboard a ship in the northeast Pacific showed a retrieval accuracy of ±25% to ±30% for individual satellite overpasses. The methodology is presently limited to boundary <span class="hlt">layer</span> not raining convective <span class="hlt">clouds</span> of at least 1 km depth that are not obscured by upper <span class="hlt">layer</span> <span class="hlt">clouds</span>, including semitransparent cirrus. The limitation for small solar backscattering angles of <25º restricts the satellite coverage to ~25% of the world area in a single day. This methodology will likely allow overcoming the challenge of quantifying the aerosol indirect effect and facilitate a substantial reduction of the uncertainty in anthropogenic climate forcing.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012epsc.conf..478O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012epsc.conf..478O"><span>3.6 cm signal attenuation in Venus' lower and <span class="hlt">middle</span> atmosphere observed by the Radio Science experiment VeRa onboard Venus Express</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Oschlisniok, J.; Tellmann, S.; Pätzold, M.; Häusler, B.; Andert, T.; Bird, M.; Remus, S.</p> <p>2012-09-01</p> <p>The planet Venus is shrouded within a roughly 20 km thick <span class="hlt">cloud</span> <span class="hlt">layer</span>, which extends from the lower to the <span class="hlt">middle</span> atmosphere (ca. 50 - 70 km). While the <span class="hlt">clouds</span> are mostly composed of sulfuric acid droplets, a haze <span class="hlt">layer</span> of sulfuric acid vapor exists below the <span class="hlt">clouds</span>. Within the <span class="hlt">cloud</span> and the sub - <span class="hlt">cloud</span> region Radio signal strength variations (intensity scintillations) caused by atmospheric waves and a decrease in the signal intensity caused by absorption by H2SO4 are observed by radio occultation experiments. The Venus Express spacecraft is orbiting Venus since 2006. The Radio Science Experiment VeRa probes the atmosphere with radio signals at 3.6 cm (XBand) and 13 cm (S-Band) wavelengths. The disturbance of the radio signal intensity is used to investigate the <span class="hlt">cloud</span> region with respect to atmospheric waves. The absorption of the signal is used to determine the abundance of H2SO4 near the <span class="hlt">cloud</span> base. This way a detailed study of the H2SO4 abundance within the <span class="hlt">cloud</span> and sub - <span class="hlt">cloud</span> region is possible. Results from the intensity scintillations within the <span class="hlt">cloud</span> deck are presented and compared with gravity wave studies based on temperature variations inferred from VeRa soundings. Vertical absorptivity profiles and resulting sulfuric acid vapor profiles are presented and compared with previous missions. A distinct latitudinal dependence and a southern northern symmetry are clearly visible.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA04329&hterms=worlds+oceans&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dworlds%2Boceans','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA04329&hterms=worlds+oceans&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dworlds%2Boceans"><span>Multi-<span class="hlt">layer</span> <span class="hlt">Clouds</span> Over the South Indian Ocean</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2003-01-01</p> <p><p/>The complex structure and beauty of polar <span class="hlt">clouds</span> are highlighted by these images acquired by the Multi-angle Imaging SpectroRadiometer (MISR) on April 23, 2003. These <span class="hlt">clouds</span> occur at multiple altitudes and exhibit a noticeable cyclonic circulation over the Southern Indian Ocean, to the north of Enderbyland, East Antarctica.<p/>The image at left was created by overlying a natural-color view from MISR's downward-pointing (nadir) camera with a color-coded stereo height field. MISR retrieves heights by a pattern recognition algorithm that utilizes multiple view angles to derive <span class="hlt">cloud</span> height and motion. The opacity of the height field was then reduced until the field appears as a translucent wash over the natural-color image. The resulting purple, cyan and green hues of this aesthetic display indicate low, medium or high altitudes, respectively, with heights ranging from less than 2 kilometers (purple) to about 8 kilometers (green). In the lower right corner, the edge of the Antarctic coastline and some sea ice can be seen through some thin, high cirrus <span class="hlt">clouds</span>.<p/>The right-hand panel is a natural-color image from MISR's 70-degree backward viewing camera. This camera looks backwards along the path of Terra's flight, and in the southern hemisphere the Sun is in front of this camera. This perspective causes the <span class="hlt">cloud</span>-tops to be brightly outlined by the sun behind them, and enhances the shadows cast by <span class="hlt">clouds</span> with significant vertical structure. An oblique observation angle also enhances the reflection of light by atmospheric particles, and accentuates the appearance of polar <span class="hlt">clouds</span>. The dark ocean and sea ice that were apparent through the cirrus <span class="hlt">clouds</span> at the bottom right corner of the nadir image are overwhelmed by the brightness of these <span class="hlt">clouds</span> at the oblique view.<p/>The Multi-angle Imaging SpectroRadiometer observes the daylit Earth continuously from pole to pole, and every 9 days views the entire globe between 82 degrees north and 82 degrees south latitude</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AMT.....9..909F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AMT.....9..909F"><span>Synergy of stereo <span class="hlt">cloud</span> top height and ORAC optimal estimation <span class="hlt">cloud</span> retrieval: evaluation and application to AATSR</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fisher, Daniel; Poulsen, Caroline A.; Thomas, Gareth E.; Muller, Jan-Peter</p> <p>2016-03-01</p> <p>In this paper we evaluate the impact on the <span class="hlt">cloud</span> parameter retrievals of the ORAC (Optimal Retrieval of Aerosol and <span class="hlt">Cloud</span>) algorithm following the inclusion of stereo-derived <span class="hlt">cloud</span> top heights as a priori information. This is performed in a mathematically rigorous way using the ORAC optimal estimation retrieval framework, which includes the facility to use such independent a priori information. Key to the use of a priori information is a characterisation of their associated uncertainty. This paper demonstrates the improvements that are possible using this approach and also considers their impact on the microphysical <span class="hlt">cloud</span> parameters retrieved. The Along-Track Scanning Radiometer (AATSR) instrument has two views and three thermal channels, so it is well placed to demonstrate the synergy of the two techniques. The stereo retrieval is able to improve the accuracy of the retrieved <span class="hlt">cloud</span> top height when compared to collocated <span class="hlt">Cloud</span>-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO), particularly in the presence of boundary <span class="hlt">layer</span> inversions and high <span class="hlt">clouds</span>. The impact of the stereo a priori information on the microphysical <span class="hlt">cloud</span> properties of <span class="hlt">cloud</span> optical thickness (COT) and effective radius (RE) was evaluated and generally found to be very small for single-<span class="hlt">layer</span> <span class="hlt">clouds</span> conditions over open water (mean RE differences of 2.2 (±5.9) microns and mean COD differences of 0.5 (±1.8) for single-<span class="hlt">layer</span> ice <span class="hlt">clouds</span> over open water at elevations of above 9 km, which are most strongly affected by the inclusion of the a priori).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20080006492','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20080006492"><span>The Mixed-Phase Arctic <span class="hlt">Cloud</span> Experiment (M-PACE)</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Verlinde, J.; Harrington, J. Y.; McFarquhar, G. M.; Yannuzzi, V. T.; Avramov, A.; Greenberg, S.; Johnson, N.; Zhang, G.; Poellot, M. R.; Mather, J. H.; <a style="text-decoration: none; " href="javascript:void(0); " onClick="displayelement('author_20080006492'); toggleEditAbsImage('author_20080006492_show'); toggleEditAbsImage('author_20080006492_hide'); "> <img style="display:inline; width:12px; height:12px; " src="images/arrow-up.gif" width="12" height="12" border="0" alt="hide" id="author_20080006492_show"> <img style="width:12px; height:12px; display:none; " src="images/arrow-down.gif" width="12" height="12" border="0" alt="hide" id="author_20080006492_hide"></p> <p>2007-01-01</p> <p>The Mixed-Phase Arctic <span class="hlt">Cloud</span> Experiment (M-PACE) was conducted September 27 through October 22, 2004 on the North Slope of Alaska. The primary objective was to collect a data set suitable to study interactions between microphysics, dynamics and radiative transfer in mixed-phase Arctic <span class="hlt">clouds</span>. Observations taken during the 1997/1998 Surface Heat and Energy Budget of the Arctic (SHEBA) experiment revealed that Arctic <span class="hlt">clouds</span> frequently consist of one (or more) liquid <span class="hlt">layers</span> precipitating ice. M-PACE sought to investigate the physical processes of these <span class="hlt">clouds</span> utilizing two aircraft (an in situ aircraft to characterize the microphysical properties of the <span class="hlt">clouds</span> and a remote sensing aircraft to constraint the upwelling radiation) over the Department of Energy s Atmospheric Radiation Measurement (ARM) Climate Research Facility (ACRF) on the North Slope of Alaska. The measurements successfully documented the microphysical structure of Arctic mixed-phase <span class="hlt">clouds</span>, with multiple in situ profiles collected in both single-<span class="hlt">layer</span> and multi-<span class="hlt">layer</span> <span class="hlt">clouds</span> over two ground-based remote sensing sites. Liquid was found in <span class="hlt">clouds</span> with temperatures down to -30 C, the coldest <span class="hlt">cloud</span> top temperature below -40 C sampled by the aircraft. Remote sensing instruments suggest that ice was present in low concentrations, mostly concentrated in precipitation shafts, although there are indications of light ice precipitation present below the optically thick single-<span class="hlt">layer</span> <span class="hlt">clouds</span>. The prevalence of liquid down to these low temperatures could potentially be explained by the relatively low measured ice nuclei concentrations.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_11 --> <div id="page_12" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="221"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19950043413&hterms=sage&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dsage','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950043413&hterms=sage&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dsage"><span>Comparison between SAGE II and ISCCP high-level <span class="hlt">clouds</span>. 2: Locating <span class="hlt">clouds</span> tops</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Liao, Xiaohan; Rossow, William B.; Rind, David</p> <p>1995-01-01</p> <p>A comparison is made of the vertical distribution of high-level <span class="hlt">cloud</span> tops derived from the Stratospheric Aerosol and Gas Experiment II (SAGE II) occultation measurements and from the International Satellite <span class="hlt">Cloud</span> Climatology Project (ISCCP) for all Julys and Januarys in 1985 to 1990. The results suggest that ISCCP overestimates the pressure of high-level <span class="hlt">clouds</span> by up to 50-150 mbar, particularly at low latitudes. This is caused by the frequent presence of <span class="hlt">clouds</span> with diffuse tops (greater than 50% time when cloudy events are observed). The averaged vertical extent of the diffuse top is about 1.5 km. At midlatitudes where the SAGE II and ISCCP <span class="hlt">cloud</span> top pressure agree best, <span class="hlt">clouds</span> with distinct tops reach a maximum relative proportion of the total level <span class="hlt">cloud</span> amount (about 30-40%), and diffuse-topped <span class="hlt">clouds</span> are reduced to their minimum (30-40%). The ISCCP-defined <span class="hlt">cloud</span> top pressure should be regarded not as the material physical height of the <span class="hlt">clouds</span> but as the level which emits the same infrared radiance as observed. SAGE II and ISCCP <span class="hlt">cloud</span> top pressures agree for <span class="hlt">clouds</span> with distinct tops. There is also an indication that the <span class="hlt">cloud</span> top pressures of optically thin <span class="hlt">clouds</span> not overlying thicker <span class="hlt">clouds</span> are poorly estimated by ISCCP at <span class="hlt">middle</span> latitudes. The average vertical extent of these thin <span class="hlt">clouds</span> is about 2.5 km.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27816440','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27816440"><span>Surface tension and quasi-emulsion of cavitation bubble <span class="hlt">cloud</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bai, Lixin; Chen, Xiaoguang; Zhu, Gang; Xu, Weilin; Lin, Weijun; Wu, Pengfei; Li, Chao; Xu, Delong; Yan, Jiuchun</p> <p>2017-03-01</p> <p>A quasi-emulsion phenomenon of cavitation structure in a thin liquid <span class="hlt">layer</span> (the thin liquid <span class="hlt">layer</span> is trapped between a radiating surface and a hard reflector) is investigated experimentally with high-speed photography. The transformation from <span class="hlt">cloud</span>-in-water (c/w) emulsion to water-in-<span class="hlt">cloud</span> (w/c) emulsion is related to the increase of cavitation bubble <span class="hlt">cloud</span>. The acoustic field in the thin liquid <span class="hlt">layer</span> is analyzed. It is found that the liquid region has higher acoustic pressure than the <span class="hlt">cloud</span> region. The bubbles are pushed from liquid region to <span class="hlt">cloud</span> region by the primary Bjerknes forces. The rate of change of CSF increased with the increase of CSF. The cavitation bubbles on the surface of cavitation <span class="hlt">cloud</span> are attracted by the cavitation bubbles inside the <span class="hlt">cloud</span> due to secondary Bjerknes forces. The existence of surface tension on the interface of liquid region and <span class="hlt">cloud</span> region is proved. The formation mechanism of disc-shaped liquid region and <span class="hlt">cloud</span> region are analysed by surface tension and incompressibility of cavitation bubble <span class="hlt">cloud</span>. Copyright © 2016 Elsevier B.V. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.A13C2067W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.A13C2067W"><span>Coupling of <span class="hlt">Clouds</span> and Moisture Transport in Extratropical Cyclonic Systems and the Associated Atmospheric Heating (Q1) and Moisture Sink (Q2)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wong, S.; Naud, C. M.; Kahn, B. H.; Wu, L.; Fetzer, E. J.</p> <p>2017-12-01</p> <p>Different sectors in extratropical cyclonic systems (ETCs) exhibit various patterns in atmospheric moisture transport and provide an excellent test bed for studying coupling between <span class="hlt">cloud</span> processes and large-scale circulation. Large-scale atmospheric moisture transport diagnosed from the Modern-Era Retrospective analysis for Research and Applications Version 2 and <span class="hlt">cloud</span> properties (<span class="hlt">cloud</span> top pressure and optical depth, <span class="hlt">cloud</span> effective radii and thermodynamic phase) from both the Moderate Resolution Imaging Spectroradiometer (MODIS) and Atmospheric Infrared Sounder (AIRS) will be composited around Northern Hemispheric ETCs over ocean according to their stages of development. Atmospheric diabatic heating rates (Q1) and moisture sinks (Q2) are also inferred from the reanalysis winds, temperature, and specific humidity. Across the warm fronts, elevated convection in the pre-warm front regime is associated with frequent stratiform <span class="hlt">clouds</span> with <span class="hlt">middle</span>-to-upper tropospheric heating and lower tropospheric cooling, while upright convection in the warm front regime has frequent deep convective <span class="hlt">clouds</span> with free-tropospheric heating and strong boundary <span class="hlt">layer</span> cooling. Thinner stratiform and cirrus <span class="hlt">clouds</span> are evident in the warm sector with top-heavy profiles of rising motion and diabatic heating. Moisture advection exhibits a sharp gradient across the cold fronts, with convection in the pre-cold front regime highly dependent on the stage of the ETC development. Heating in the boundary <span class="hlt">layers</span> of the cold sector, polar-air intrusion, and pre-warm sector regimes depends on the amount of low-level <span class="hlt">clouds</span>, which is again modulated by the stage of the ETC development.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.A41J..03P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.A41J..03P"><span>Efficacy of <span class="hlt">Cloud</span>-Radiative Perturbations in Deep Open- and Closed-Cell Stratocumulus <span class="hlt">Clouds</span> due to Aerosol Perturbations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Possner, A.; Wang, H.; Caldeira, K.; Wood, R.; Ackerman, T. P.</p> <p>2017-12-01</p> <p>Aerosol-<span class="hlt">cloud</span> interactions (ACIs) in marine stratocumulus remain a significant source of uncertainty in constraining the <span class="hlt">cloud</span>-radiative effect in a changing climate. Ship tracks are undoubted manifestations of ACIs embedded within stratocumulus <span class="hlt">cloud</span> decks and have proven to be a useful framework to study the effect of aerosol perturbations on <span class="hlt">cloud</span> morphology, macrophysical, microphyiscal and <span class="hlt">cloud</span>-radiative properties. However, so far most observational (Christensen et al. 2012, Chen et al. 2015) and numerical studies (Wang et al. 2011, Possner et al. 2015, Berner et al. 2015) have concentrated on ship tracks in shallow boundary <span class="hlt">layers</span> of depths between 300 - 800 m, while most stratocumulus decks form in significantly deeper boundary <span class="hlt">layers</span> (Muhlbauer et al. 2014). In this study we investigate the efficacy of aerosol perturbations in deep open and closed cell stratocumulus. Multi-day idealised <span class="hlt">cloud</span>-resolving simulations are performed for the RF06 flight of the VOCALS-Rex field campaign (Wood et al. 2011). During this flight pockets of deep open and closed cells were observed in a 1410 m deep boundary <span class="hlt">layer</span>. The efficacy of aerosol perturbations of varied concentration and spatial gradients in altering the <span class="hlt">cloud</span> micro- and macrophysical state and <span class="hlt">cloud</span>-radiative effect is determined in both <span class="hlt">cloud</span> regimes. Our simulations show that a continued point source emission flux of 1.16*1011 particles m-2 s-1 applied within a 300x300 m2 gridbox induces pronounced <span class="hlt">cloud</span> cover changes in approximately a third of the simulated 80x80 km2 domain, a weakening of the diurnal cycle in the open-cell regime and a resulting increase in domain-mean <span class="hlt">cloud</span> albedo of 0.2. Furthermore, we contrast the efficacy of equal strength near-surface or above-<span class="hlt">cloud</span> aerosol perturbations in altering the <span class="hlt">cloud</span> state.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011ACP....11.9943Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011ACP....11.9943Z"><span>Observations of the boundary <span class="hlt">layer</span>, <span class="hlt">cloud</span>, and aerosol variability in the southeast Pacific near-coastal marine stratocumulus during VOCALS-REx</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zheng, X.; Albrecht, B.; Jonsson, H. H.; Khelif, D.; Feingold, G.; Minnis, P.; Ayers, K.; Chuang, P.; Donaher, S.; Rossiter, D.; Ghate, V.; Ruiz-Plancarte, J.; Sun-Mack, S.</p> <p>2011-09-01</p> <p>Aircraft observations made off the coast of northern Chile in the Southeastern Pacific (20° S, 72° W; named Point Alpha) from 16 October to 13 November 2008 during the VAMOS Ocean-<span class="hlt">Cloud</span>- Atmosphere-Land Study-Regional Experiment (VOCALS-REx), combined with meteorological reanalysis, satellite measurements, and radiosonde data, are used to investigate the boundary <span class="hlt">layer</span> (BL) and aerosol-<span class="hlt">cloud</span>-drizzle variations in this region. On days without predominately synoptic and meso-scale influences, the BL at Point Alpha was typical of a non-drizzling stratocumulus-topped BL. Entrainment rates calculated from the near <span class="hlt">cloud</span>-top fluxes and turbulence in the BL at Point Alpha appeared to be weaker than those in the BL over the open ocean west of Point Alpha and the BL near the coast of the northeast Pacific. The <span class="hlt">cloud</span> liquid water path (LWP) varied between 15 g m-2 and 160 g m-2. The BL had a depth of 1140 ± 120 m, was generally well-mixed and capped by a sharp inversion without predominately synoptic and meso-scale influences. The wind direction generally switched from southerly within the BL to northerly above the inversion. On days when a synoptic system and related mesoscale costal circulations affected conditions at Point Alpha (29 October-4 November), a moist <span class="hlt">layer</span> above the inversion moved over Point Alpha, and the total-water mixing ratio above the inversion was larger than that within the BL. The accumulation mode aerosol varied from 250 to 700 cm-3 within the BL, and CCN at 0.2 % supersaturation within the BL ranged between 150 and 550 cm-3. The main aerosol source at Point Alpha was horizontal advection within the BL from south. The average <span class="hlt">cloud</span> droplet number concentration ranged between 80 and 400 cm-3. While the mean LWP retrieved from GOES was in good agreement with the in situ measurements, the GOES-derived <span class="hlt">cloud</span> droplet effective radius tended to be larger than that from the aircraft in situ observations near <span class="hlt">cloud</span> top. The aerosol and <span class="hlt">cloud</span> LWP</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140009174','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140009174"><span>Global Free Tropospheric NO2 Abundances Derived Using a <span class="hlt">Cloud</span> Slicing Technique Applied to Satellite Observations from the Aura Ozone Monitoring Instrument (OMI)</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Choi, S.; Joiner, J.; Choi, Y.; Duncan, B. N.; Bucsela, E.</p> <p>2014-01-01</p> <p>We derive free-tropospheric NO2 volume mixing ratios (VMRs) and stratospheric column amounts of NO2 by applying a <span class="hlt">cloud</span> slicing technique to data from the Ozone Monitoring Instrument (OMI) on the Aura satellite. In the <span class="hlt">cloud</span>-slicing approach, the slope of the above-<span class="hlt">cloud</span> NO2 column versus the <span class="hlt">cloud</span> scene pressure is proportional to the NO2 VMR. In this work, we use a sample of nearby OMI pixel data from a single orbit for the linear fit. The OMI data include <span class="hlt">cloud</span> scene pressures from the rotational-Raman algorithm and above-<span class="hlt">cloud</span> NO2 vertical column density (VCD) (defined as the NO2 column from the <span class="hlt">cloud</span> scene pressure to the top-of-the-atmosphere) from a differential optical absorption spectroscopy (DOAS) algorithm. Estimates of stratospheric column NO2 are obtained by extrapolating the linear fits to the tropopause. We compare OMI-derived NO2 VMRs with in situ aircraft profiles measured during the NASA Intercontinental Chemical Transport Experiment Phase B (INTEX-B) campaign in 2006. The agreement is generally within the estimated uncertainties when appropriate data screening is applied. We then derive a global seasonal climatology of free-tropospheric NO2 VMR in cloudy conditions. Enhanced NO2 in the free troposphere commonly appears near polluted urban locations where NO2 produced in the boundary <span class="hlt">layer</span> may be transported vertically out of the boundary <span class="hlt">layer</span> and then horizontally away from the source. Signatures of lightning NO2 are also shown throughout low and <span class="hlt">middle</span> latitude regions in summer months. A profile analysis of our <span class="hlt">cloud</span> slicing data indicates signatures of uplifted and transported anthropogenic NO2 in the <span class="hlt">middle</span> troposphere as well as lightning-generated NO2 in the upper troposphere. Comparison of the climatology with simulations from the Global Modeling Initiative (GMI) for cloudy conditions (<span class="hlt">cloud</span> optical thicknesses > 10) shows similarities in the spatial patterns of continental pollution outflow. However, there are also some differences in</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040171157&hterms=coverage&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dcoverage','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040171157&hterms=coverage&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dcoverage"><span><span class="hlt">Cloud</span> Coverage and Height Distribution from the GLAS Polar Orbiting Lidar: Comparison to Passive <span class="hlt">Cloud</span> Retrievals</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Spinhime, J. D.; Palm, S. P.; Hlavka, D. L.; Hart, W. D.; Mahesh, A.</p> <p>2004-01-01</p> <p>The Geoscience Laser Altimeter System (GLAS) began full on orbit operations in September 2003. A main application of the two-wavelength GLAS lidar is highly accurate detection and profiling of global <span class="hlt">cloud</span> cover. Initial analysis indicates that <span class="hlt">cloud</span> and aerosol <span class="hlt">layers</span> are consistently detected on a global basis to cross-sections down to 10(exp -6) per meter. Images of the lidar data dramatically and accurately show the vertical structure of <span class="hlt">cloud</span> and aerosol to the limit of signal attenuation. The GLAS lidar has made the most accurate measurement of global <span class="hlt">cloud</span> coverage and height to date. In addition to the calibrated lidar signal, GLAS data products include multi level boundaries and optical depth of all transmissive <span class="hlt">layers</span>. Processing includes a multi-variable separation of <span class="hlt">cloud</span> and aerosol <span class="hlt">layers</span>. An initial application of the data results is to compare monthly <span class="hlt">cloud</span> means from several months of GLAS observations in 2003 to existing <span class="hlt">cloud</span> climatologies from other satellite measurement. In some cases direct comparison to passive <span class="hlt">cloud</span> retrievals is possible. A limitation of the lidar measurements is nadir only sampling. However monthly means exhibit reasonably good global statistics and coverage results, at other than polar regions, compare well with other measurements but show significant differences in height distribution. For polar regions where passive <span class="hlt">cloud</span> retrievals are problematic and where orbit track density is greatest, the GLAS results are particularly an advance in <span class="hlt">cloud</span> cover information. Direct comparison to MODIS retrievals show a better than 90% agreement in <span class="hlt">cloud</span> detection for daytime, but less than 60% at night. Height retrievals are in much less agreement. GLAS is a part of the NASA EOS project and data products are thus openly available to the science community (see http://glo.gsfc.nasa.gov).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20110020277&hterms=HISTOGRAM&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DHISTOGRAM','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20110020277&hterms=HISTOGRAM&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DHISTOGRAM"><span>Vertical Structures of Anvil <span class="hlt">Clouds</span> of Tropical Mesoscale Convective Systems Observed by <span class="hlt">Cloud</span>Sat</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hence, Deanna A.; Houze, Robert A.</p> <p>2011-01-01</p> <p>A global study of the vertical structures of the <span class="hlt">clouds</span> of tropical mesoscale convective systems (MCSs) has been carried out with data from the <span class="hlt">Cloud</span>Sat <span class="hlt">Cloud</span> Profiling Radar. Tropical MCSs are found to be dominated by <span class="hlt">cloud</span>-top heights greater than 10 km. Secondary <span class="hlt">cloud</span> <span class="hlt">layers</span> sometimes occur in MCSs, but outside their primary raining cores. The secondary <span class="hlt">layers</span> have tops at 6 8 and 1 3 km. High-topped <span class="hlt">clouds</span> extend outward from raining cores of MCSs to form anvil <span class="hlt">clouds</span>. Closest to the raining cores, the anvils tend to have broader distributions of reflectivity at all levels, with the modal values at higher reflectivity in their lower levels. Portions of anvil <span class="hlt">clouds</span> far away from the raining core are thin and have narrow frequency distributions of reflectivity at all levels with overall weaker values. This difference likely reflects ice particle fallout and therefore <span class="hlt">cloud</span> age. Reflectivity histograms of MCS anvil <span class="hlt">clouds</span> vary little across the tropics, except that (i) in continental MCS anvils, broader distributions of reflectivity occur at the uppermost levels in the portions closest to active raining areas; (ii) the frequency of occurrence of stronger reflectivity in the upper part of anvils decreases faster with increasing distance in continental MCSs; and (iii) narrower-peaked ridges are prominent in reflectivity histograms of thick anvil <span class="hlt">clouds</span> close to the raining areas of connected MCSs (superclusters). These global results are consistent with observations at ground sites and aircraft data. They present a comprehensive test dataset for models aiming to simulate process-based upper-level <span class="hlt">cloud</span> structure around the tropics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20110023303&hterms=HISTOGRAM&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DHISTOGRAM','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20110023303&hterms=HISTOGRAM&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DHISTOGRAM"><span>Vertical Structures of Anvil <span class="hlt">Clouds</span> of Tropical Mesoscale Convective Systems Observed by <span class="hlt">Cloud</span>Sat</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Yuan, J.; Houze, R. A., Jr.; Heymsfield, A.</p> <p>2011-01-01</p> <p>A global study of the vertical structures of the <span class="hlt">clouds</span> of tropical mesoscale convective systems (MCSs) has been carried out with data from the <span class="hlt">Cloud</span>Sat <span class="hlt">Cloud</span> Profiling Radar. Tropical MCSs are found to be dominated by <span class="hlt">cloud</span>-top heights greater than 10 km. Secondary <span class="hlt">cloud</span> <span class="hlt">layers</span> sometimes occur in MCSs, but outside their primary raining cores. The secondary <span class="hlt">layers</span> have tops at 6--8 and 1--3 km. High-topped <span class="hlt">clouds</span> extend outward from raining cores of MCSs to form anvil <span class="hlt">clouds</span>. Closest to the raining cores, the anvils tend to have broader distributions of reflectivity at all levels, with the modal values at higher reflectivity in their lower levels. Portions of anvil <span class="hlt">clouds</span> far away from the raining core are thin and have narrow frequency distributions of reflectivity at all levels with overall weaker values. This difference likely reflects ice particle fallout and therefore <span class="hlt">cloud</span> age. Reflectivity histograms of MCS anvil <span class="hlt">clouds</span> vary little across the tropics, except that (i) in continental MCS anvils, broader distributions of reflectivity occur at the uppermost levels in the portions closest to active raining areas; (ii) the frequency of occurrence of stronger reflectivity in the upper part of anvils decreases faster with increasing distance in continental MCSs; and (iii) narrower-peaked ridges are prominent in reflectivity histograms of thick anvil <span class="hlt">clouds</span> close to the raining areas of connected MCSs (superclusters). These global results are consistent with observations at ground sites and aircraft data. They present a comprehensive test dataset for models aiming to simulate process-based upper-level <span class="hlt">cloud</span> structure around the tropics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010JGRD..11519116L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010JGRD..11519116L"><span>Observations of Kelvin-Helmholtz instability at a <span class="hlt">cloud</span> base with the <span class="hlt">middle</span> and upper atmosphere (MU) and weather radars</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Luce, Hubert; Mega, Tomoaki; Yamamoto, Masayuki K.; Yamamoto, Mamoru; Hashiguchi, Hiroyuki; Fukao, Shoichiro; Nishi, Noriyuki; Tajiri, Takuya; Nakazato, Masahisa</p> <p>2010-10-01</p> <p>Using the very high frequency (46.5 MHz) <span class="hlt">middle</span> and upper atmosphere radar (MUR), Ka band (35 GHz) and X band (9.8 GHz) weather radars, a Kelvin-Helmholtz (KH) instability occurring at a <span class="hlt">cloud</span> base and its impact on modulating <span class="hlt">cloud</span> bottom altitudes are described by a case study on 8 October 2008 at the Shigaraki MU Observatory, Japan (34.85°N, 136.10°E). KH braids were monitored by the MUR along the slope of a <span class="hlt">cloud</span> base gradually rising with time around an altitude of ˜5.0 km. The KH braids had a horizontal wavelength of about 3.6 km and maximum crest-to-trough amplitude of about 1.6 km. Nearly monochromatic and out of phase vertical air motion oscillations exceeding ±3 m s-1 with a period of ˜3 min 20 s were measured by the MUR above and below the <span class="hlt">cloud</span> base. The axes of the billows were at right angles of the wind and wind shear both oriented east-north-east at their altitude. The isotropy of the radar echoes and the large variance of Doppler velocity in the KH billows (including the braids) indicate the presence of strong turbulence at the Bragg (˜3.2 m) scale. After the passage of the <span class="hlt">cloud</span> system, the KH waves rapidly damped and the vertical scale of the KH braids progressively decreased down to about 100 m before their disappearance. The radar observations suggest that the interface between clear air and <span class="hlt">cloud</span> was conducive to the presence of the dynamical shear instability by reducing static stability (and then the Richardson number) near the <span class="hlt">cloud</span> base. Downward cloudy protuberances detected by the Ka band radar had vertical and horizontal scales of about 0.6-1.1 and 3.2 km, respectively, and were clearly associated with the downward air motions. Observed oscillations of the reflectivity-weighted Doppler velocity measured by the X band radar indicate that falling ice particles underwent the vertical wind motions generated by the KH instability to form the protuberances. The protuberances at the <span class="hlt">cloud</span> base might be either KH billow <span class="hlt">clouds</span> or perhaps</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018ClDy...50.2457W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018ClDy...50.2457W"><span>Dynamical and thermodynamical coupling between the North Atlantic subtropical high and the marine boundary <span class="hlt">layer</span> <span class="hlt">clouds</span> in boreal summer</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wei, Wei; Li, Wenhong; Deng, Yi; Yang, Song; Jiang, Jonathan H.; Huang, Lei; Liu, W. Timothy</p> <p>2018-04-01</p> <p>This study investigates dynamical and thermodynamical coupling between the North Atlantic subtropical high (NASH), marine boundary <span class="hlt">layer</span> (MBL) <span class="hlt">clouds</span>, and the local sea surface temperatures (SSTs) over the North Atlantic in boreal summer for 1984-2009 using NCEP/DOE Reanalysis 2 dataset, various <span class="hlt">cloud</span> data, and the Hadley Centre sea surface temperature. On interannual timescales, the summer mean subtropical MBL <span class="hlt">clouds</span> to the southeast of the NASH is actively coupled with the NASH and local SSTs: a stronger (weaker) NASH is often accompanied with an increase (a decrease) of MBL <span class="hlt">clouds</span> and abnormally cooler (warmer) SSTs along the southeast flank of the NASH. To understand the physical processes between the NASH and the MBL <span class="hlt">clouds</span>, the authors conduct a data diagnostic analysis and implement a numerical modeling investigation using an idealized anomalous atmospheric general circulation model (AGCM). Results suggest that significant northeasterly anomalies in the southeast flank of the NASH associated with an intensified NASH tend to induce stronger cold advection and coastal upwelling in the MBL <span class="hlt">cloud</span> region, reducing the boundary surface temperature. Meanwhile, warm advection associated with the easterly anomalies from the African continent leads to warming over the MBL <span class="hlt">cloud</span> region at 700 hPa. Such warming and the surface cooling increase the atmospheric static stability, favoring growth of the MBL <span class="hlt">clouds</span>. The anomalous diabatic cooling associated with the growth of the MBL <span class="hlt">clouds</span> dynamically excites an anomalous anticyclone to its north and contributes to strengthening of the NASH circulation in its southeast flank. The dynamical and thermodynamical couplings and their associated variations in the NASH, MBL <span class="hlt">clouds</span>, and SSTs constitute an important aspect of the summer climate variability over the North Atlantic.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008JGRD..113.0A16B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008JGRD..113.0A16B"><span>A comparison between <span class="hlt">Cloud</span>Sat and aircraft data for a multilayer, mixed phase <span class="hlt">cloud</span> system during the Canadian <span class="hlt">Cloud</span>Sat-CALIPSO Validation Project</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Barker, H. W.; Korolev, A. V.; Hudak, D. R.; Strapp, J. W.; Strawbridge, K. B.; Wolde, M.</p> <p>2008-04-01</p> <p>Reflectivities recorded by the W-band <span class="hlt">Cloud</span> Profiling Radar (CPR) aboard NASA's <span class="hlt">Cloud</span>Sat satellite and some of <span class="hlt">Cloud</span>Sat's retrieval products are compared to Ka-band radar reflectivities and in situ <span class="hlt">cloud</span> properties gathered by instrumentation on the NRC's Convair-580 aircraft. On 20 February 2007, the Convair flew several transects along a 60 nautical mile stretch of <span class="hlt">Cloud</span>Sat's afternoon ground track over southern Quebec. On one of the transects it was well within <span class="hlt">Cloud</span>Sat's radar's footprint while in situ sampling a mixed phase boundary <span class="hlt">layer</span> <span class="hlt">cloud</span>. A cirrus <span class="hlt">cloud</span> was also sampled before and after overpass. Air temperature and humidity profiles from ECMWF reanalyses, as employed in <span class="hlt">Cloud</span>Sat's retrieval stream, agree very well with those measured by the Convair. The boundary <span class="hlt">layer</span> <span class="hlt">cloud</span> was clearly visible, to the eye and lidar, and dominated the region's solar radiation budget. It was, however, often below or near the Ka-band's distance-dependent minimum detectable signal. In situ samples at overpass revealed it to be composed primarily of small, supercooled droplets at the south end and increasingly intermixed with ice northward. Convair and <span class="hlt">Cloud</span>Sat CPR reflectivities for the low <span class="hlt">cloud</span> agree well, but while <span class="hlt">Cloud</span>Sat properly ascribed it as overcast, mixed phase, and mostly liquid near the south end, its estimates of liquid water content LWC (and visible extinction coefficient κ) and droplet effective radii are too small and large, respectively. The cirrus consisted largely of irregular crystals with typical effective radii ˜150 μm. While both CPR reflectivities agree nicely, <span class="hlt">Cloud</span>Sat's estimates of crystal number concentrations are too large by a factor of 5. Nevertheless, distributions of ice water content and κ deduced from in situ data agree quite well with values retrieved from <span class="hlt">Cloud</span>Sat algorithms.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.A41J..08H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.A41J..08H"><span>On the Vertical Nature of Biomass Burning Plumes by the California Coast and Their Relationship with Marine Boundary <span class="hlt">Layer</span> <span class="hlt">Clouds</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hu, L.; Montzka, S. A.; Godwin, D.; Andrews, A. E.; Thoning, K. W.; Miller, B. R.; Sweeney, C.; Miller, J. B.; Lehman, S.; Siso, C.; Mondeel, D. J.; Hall, B. D.; Nance, J. D.; Tans, P. P.; Elkins, J. W.</p> <p>2016-12-01</p> <p>Biomass burning (BB) plumes can significantly impact stratocumulus <span class="hlt">clouds</span> (Sc), the dominant <span class="hlt">cloud</span> type by global area, by altering their microphysical properties. The California (CA) coast is home to one of the three major semi-permanent stratocumulus (Sc) <span class="hlt">cloud</span> decks in the world and BB emissions are of growing concern in the western United States, owing to both a warmer climate and fire-control strategies over recent decades. The thickness and vertical position of BB plumes, especially relative to <span class="hlt">clouds</span>, is critical to understand how the aerosol will affect the thermodynamic structure of the atmosphere, <span class="hlt">cloud</span> properties, and radiative forcing. This study reports on the characterization of the vertical, spatial, and temporal nature of BB aerosol over coastal CA, based on airborne data collected in the months of July and August for 2013 and 2016. Results from over 100 soundings indicate that multiple BB plume <span class="hlt">layers</span> exist above <span class="hlt">clouds</span>, with the thickness of BB plumes and their vertical position relative to <span class="hlt">cloud</span> top varying significantly as a function of distance from coastline. Comparison of soundings at a given location at two different times of day reveals significant variation in BB characteristics. Intercomparisons for BB plume characteristics are explored between the field data, NAAPS, and CALIPSO.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.A41J..08H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.A41J..08H"><span>On the Vertical Nature of Biomass Burning Plumes by the California Coast and Their Relationship with Marine Boundary <span class="hlt">Layer</span> <span class="hlt">Clouds</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hossein Mardi, A.; MacDonald, A. B.; Dadashazar, H.; Crosbie, E.; WANG, Z.; Lynch, P.; Campbell, J. R.; Jonsson, H.; Sorooshian, A.</p> <p>2017-12-01</p> <p>Biomass burning (BB) plumes can significantly impact stratocumulus <span class="hlt">clouds</span> (Sc), the dominant <span class="hlt">cloud</span> type by global area, by altering their microphysical properties. The California (CA) coast is home to one of the three major semi-permanent stratocumulus (Sc) <span class="hlt">cloud</span> decks in the world and BB emissions are of growing concern in the western United States, owing to both a warmer climate and fire-control strategies over recent decades. The thickness and vertical position of BB plumes, especially relative to <span class="hlt">clouds</span>, is critical to understand how the aerosol will affect the thermodynamic structure of the atmosphere, <span class="hlt">cloud</span> properties, and radiative forcing. This study reports on the characterization of the vertical, spatial, and temporal nature of BB aerosol over coastal CA, based on airborne data collected in the months of July and August for 2013 and 2016. Results from over 100 soundings indicate that multiple BB plume <span class="hlt">layers</span> exist above <span class="hlt">clouds</span>, with the thickness of BB plumes and their vertical position relative to <span class="hlt">cloud</span> top varying significantly as a function of distance from coastline. Comparison of soundings at a given location at two different times of day reveals significant variation in BB characteristics. Intercomparisons for BB plume characteristics are explored between the field data, NAAPS, and CALIPSO.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AMT.....5.1889P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AMT.....5.1889P"><span><span class="hlt">Cloud</span> retrievals from satellite data using optimal estimation: evaluation and application to ATSR</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Poulsen, C. A.; Siddans, R.; Thomas, G. E.; Sayer, A. M.; Grainger, R. G.; Campmany, E.; Dean, S. M.; Arnold, C.; Watts, P. D.</p> <p>2012-08-01</p> <p><span class="hlt">Clouds</span> play an important role in balancing the Earth's radiation budget. Hence, it is vital that <span class="hlt">cloud</span> climatologies are produced that quantify <span class="hlt">cloud</span> macro and micro physical parameters and the associated uncertainty. In this paper, we present an algorithm ORAC (Oxford-RAL retrieval of Aerosol and <span class="hlt">Cloud</span>) which is based on fitting a physically consistent <span class="hlt">cloud</span> model to satellite observations simultaneously from the visible to the mid-infrared, thereby ensuring that the resulting <span class="hlt">cloud</span> properties provide both a good representation of the short-wave and long-wave radiative effects of the observed <span class="hlt">cloud</span>. The advantages of the optimal estimation method are that it enables rigorous error propagation and the inclusion of all measurements and any a priori information and associated errors in a rigorous mathematical framework. The algorithm provides a measure of the consistency between retrieval representation of <span class="hlt">cloud</span> and satellite radiances. The <span class="hlt">cloud</span> parameters retrieved are the <span class="hlt">cloud</span> top pressure, <span class="hlt">cloud</span> optical depth, <span class="hlt">cloud</span> effective radius, <span class="hlt">cloud</span> fraction and <span class="hlt">cloud</span> phase. The algorithm can be applied to most visible/infrared satellite instruments. In this paper, we demonstrate the applicability to the Along-Track Scanning Radiometers ATSR-2 and AATSR. Examples of applying the algorithm to ATSR-2 flight data are presented and the sensitivity of the retrievals assessed, in particular the algorithm is evaluated for a number of simulated single-<span class="hlt">layer</span> and multi-<span class="hlt">layer</span> conditions. The algorithm was found to perform well for single-<span class="hlt">layer</span> <span class="hlt">cloud</span> except when the <span class="hlt">cloud</span> was very thin; i.e., less than 1 optical depths. For the multi-<span class="hlt">layer</span> <span class="hlt">cloud</span>, the algorithm was robust except when the upper ice <span class="hlt">cloud</span> <span class="hlt">layer</span> is less than five optical depths. In these cases the retrieved <span class="hlt">cloud</span> top pressure and <span class="hlt">cloud</span> effective radius become a weighted average of the 2 <span class="hlt">layers</span>. The sum of optical depth of multi-<span class="hlt">layer</span> <span class="hlt">cloud</span> is retrieved well until the <span class="hlt">cloud</span> becomes thick, greater than 50 optical depths</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20080044857&hterms=thermodynamics&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dthermodynamics','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20080044857&hterms=thermodynamics&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dthermodynamics"><span>Comparison of the MODIS Multilayer <span class="hlt">Cloud</span> Detection and Thermodynamic Phase Products with CALIPSO and <span class="hlt">Cloud</span>Sat</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Platnick, Steven; King, Michael D.; Wind, Gala; Holz, Robert E.; Ackerman, Steven A.; Nagle, Fred W.</p> <p>2008-01-01</p> <p>CALIPSO and <span class="hlt">Cloud</span>Sat, launched in June 2006, provide global active remote sensing measurements of <span class="hlt">clouds</span> and aerosols that can be used for validation of a variety of passive imager retrievals derived from instruments flying on the Aqua spacecraft and other A-Train platforms. The most recent processing effort for the MODIS Atmosphere Team, referred to as the "Collection 5" stream, includes a research-level multilayer <span class="hlt">cloud</span> detection algorithm that uses both thermodynamic phase information derived from a combination of solar and thermal emission bands to discriminate <span class="hlt">layers</span> of different phases, as well as true <span class="hlt">layer</span> separation discrimination using a moderately absorbing water vapor band. The multilayer detection algorithm is designed to provide a means of assessing the applicability of 1D <span class="hlt">cloud</span> models used in the MODIS <span class="hlt">cloud</span> optical and microphysical product retrieval, which are generated at a 1 h resolution. Using pixel-level collocations of MODIS Aqua, CALIOP, and <span class="hlt">Cloud</span>Sat radar measurements, we investigate the global performance of the thermodynamic phase and multilayer <span class="hlt">cloud</span> detection algorithms.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19970026660','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19970026660"><span>Global Single and Multiple <span class="hlt">Cloud</span> Classification with a Fuzzy Logic Expert System</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Welch, Ronald M.; Tovinkere, Vasanth; Titlow, James; Baum, Bryan A.</p> <p>1996-01-01</p> <p>An unresolved problem in remote sensing concerns the analysis of satellite imagery containing both single and multiple <span class="hlt">cloud</span> <span class="hlt">layers</span>. While <span class="hlt">cloud</span> parameterizations are very important both in global climate models and in studies of the Earth's radiation budget, most <span class="hlt">cloud</span> retrieval schemes, such as the bispectral method used by the International Satellite <span class="hlt">Cloud</span> Climatology Project (ISCCP), have no way of determining whether overlapping <span class="hlt">cloud</span> <span class="hlt">layers</span> exist in any group of satellite pixels. Coakley (1983) used a spatial coherence method to determine whether a region contained more than one <span class="hlt">cloud</span> <span class="hlt">layer</span>. Baum et al. (1995) developed a scheme for detection and analysis of daytime multiple <span class="hlt">cloud</span> <span class="hlt">layers</span> using merged AVHRR (Advanced Very High Resolution Radiometer) and HIRS (High-resolution Infrared Radiometer Sounder) data collected during the First ISCCP Regional Experiment (FIRE) Cirrus 2 field campaign. Baum et al. (1995) explored the use of a <span class="hlt">cloud</span> classification technique based on AVHRR data. This study examines the feasibility of applying the <span class="hlt">cloud</span> classifier to global satellite imagery.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRD..122.8852H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRD..122.8852H"><span><span class="hlt">Cloud</span> occurrences and <span class="hlt">cloud</span> radiative effects (CREs) from CERES-CALIPSO-<span class="hlt">Cloud</span>Sat-MODIS (CCCM) and <span class="hlt">Cloud</span>Sat radar-lidar (RL) products</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ham, Seung-Hee; Kato, Seiji; Rose, Fred G.; Winker, David; L'Ecuyer, Tristan; Mace, Gerald G.; Painemal, David; Sun-Mack, Sunny; Chen, Yan; Miller, Walter F.</p> <p>2017-08-01</p> <p>Two kinds of <span class="hlt">cloud</span> products obtained from <span class="hlt">Cloud</span>-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO), <span class="hlt">Cloud</span>Sat, and Moderate Resolution Imaging Spectroradiometer (MODIS) are compared and analyzed in this study: <span class="hlt">Clouds</span> and the Earth's Radiant Energy System (CERES)-CALIPSO-<span class="hlt">Cloud</span>Sat-MODIS (CCCM) product and <span class="hlt">Cloud</span>Sat radar-lidar products such as GEOPROF-LIDAR and FLXHR-LIDAR. Compared to GEOPROF-LIDAR, low-level (<1 km) <span class="hlt">cloud</span> occurrences in CCCM are larger over tropical oceans because the CCCM algorithm uses a more relaxed threshold of <span class="hlt">cloud</span>-aerosol discrimination score for CALIPSO Vertical Feature Mask product. In contrast, midlevel (1-8 km) <span class="hlt">cloud</span> occurrences in GEOPROF-LIDAR are larger than CCCM at high latitudes (>40°). The difference occurs when hydrometeors are detected by CALIPSO lidar but are undetected by <span class="hlt">Cloud</span>Sat radar. In the comparison of <span class="hlt">cloud</span> radiative effects (CREs), global mean differences between CCCM and FLXHR-LIDAR are mostly smaller than 5 W m-2, while noticeable regional differences are found. For example, CCCM shortwave (SW) and longwave (LW) CREs are larger than FXLHR-LIDAR along the west coasts of Africa and America because the GEOPROF-LIDAR algorithm misses shallow marine boundary <span class="hlt">layer</span> <span class="hlt">clouds</span>. In addition, FLXHR-LIDAR SW CREs are larger than the CCCM counterpart over tropical oceans away from the west coasts of America. Over midlatitude storm-track regions, CCCM SW and LW CREs are larger than the FLXHR-LIDAR counterpart.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1433941-scaling-drizzle-virga-depth-cloud-thickness-marine-stratocumulus-clouds','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1433941-scaling-drizzle-virga-depth-cloud-thickness-marine-stratocumulus-clouds"><span>Scaling of drizzle virga depth with <span class="hlt">cloud</span> thickness for marine stratocumulus <span class="hlt">clouds</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Yang, Fan; Luke, Edward P.; Kollias, Pavlos; ...</p> <p>2018-04-20</p> <p>Drizzle plays a crucial role in <span class="hlt">cloud</span> lifetime and radiation properties of marine stratocumulus <span class="hlt">clouds</span>. Understanding where drizzle exists in the sub-<span class="hlt">cloud</span> <span class="hlt">layer</span>, which depends on drizzle virga depth, can help us better understand where below-<span class="hlt">cloud</span> scavenging and evaporative cooling and moisturizing occur. In this study, we examine the statistical properties of drizzle frequency and virga depth of marine stratocumulus based on unique ground-based remote sensing data. Results show that marine stratocumulus <span class="hlt">clouds</span> are drizzling nearly all the time. In addition, we derive a simple scaling analysis between drizzle virga thickness and <span class="hlt">cloud</span> thickness. Our analytical expression agrees with themore » observational data reasonable well, which suggests that our formula provides a simple parameterization for drizzle virga of stratocumulus <span class="hlt">clouds</span> suitable for use in other models.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/1433941-scaling-drizzle-virga-depth-cloud-thickness-marine-stratocumulus-clouds','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/1433941-scaling-drizzle-virga-depth-cloud-thickness-marine-stratocumulus-clouds"><span>Scaling of drizzle virga depth with <span class="hlt">cloud</span> thickness for marine stratocumulus <span class="hlt">clouds</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Yang, Fan; Luke, Edward P.; Kollias, Pavlos</p> <p></p> <p>Drizzle plays a crucial role in <span class="hlt">cloud</span> lifetime and radiation properties of marine stratocumulus <span class="hlt">clouds</span>. Understanding where drizzle exists in the sub-<span class="hlt">cloud</span> <span class="hlt">layer</span>, which depends on drizzle virga depth, can help us better understand where below-<span class="hlt">cloud</span> scavenging and evaporative cooling and moisturizing occur. In this study, we examine the statistical properties of drizzle frequency and virga depth of marine stratocumulus based on unique ground-based remote sensing data. Results show that marine stratocumulus <span class="hlt">clouds</span> are drizzling nearly all the time. In addition, we derive a simple scaling analysis between drizzle virga thickness and <span class="hlt">cloud</span> thickness. Our analytical expression agrees with themore » observational data reasonable well, which suggests that our formula provides a simple parameterization for drizzle virga of stratocumulus <span class="hlt">clouds</span> suitable for use in other models.« less</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_12 --> <div id="page_13" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="241"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1197909-photolysis-rates-correlated-overlapping-cloud-fields-cloud','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1197909-photolysis-rates-correlated-overlapping-cloud-fields-cloud"><span>Photolysis rates in correlated overlapping <span class="hlt">cloud</span> fields: <span class="hlt">Cloud</span>-J 7.3</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Prather, M. J.</p> <p>2015-05-27</p> <p>A new approach for modeling photolysis rates ( J values) in atmospheres with fractional <span class="hlt">cloud</span> cover has been developed and implemented as <span class="hlt">Cloud</span>-J – a multi-scattering eight-stream radiative transfer model for solar radiation based on Fast-J. Using observed statistics for the vertical correlation of <span class="hlt">cloud</span> <span class="hlt">layers</span>, <span class="hlt">Cloud</span>-J 7.3 provides a practical and accurate method for modeling atmospheric chemistry. The combination of the new maximum-correlated <span class="hlt">cloud</span> groups with the integration over all <span class="hlt">cloud</span> combinations represented by four quadrature atmospheres produces mean J values in an atmospheric column with root-mean-square errors of 4% or less compared with 10–20% errors using simpler approximations.more » <span class="hlt">Cloud</span>-J is practical for chemistry-climate models, requiring only an average of 2.8 Fast-J calls per atmosphere, vs. hundreds of calls with the correlated <span class="hlt">cloud</span> groups, or 1 call with the simplest <span class="hlt">cloud</span> approximations. Another improvement in modeling J values, the treatment of volatile organic compounds with pressure-dependent cross sections is also incorporated into <span class="hlt">Cloud</span>-J.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20160000959','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20160000959"><span>Remote Sensing of <span class="hlt">Cloud</span> Top Heights Using the Research Scanning Polarimeter</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Sinclair, Kenneth; van Diedenhoven, Bastiaan; Cairns, Brian; Yorks, John; Wasilewski, Andrzej</p> <p>2015-01-01</p> <p><span class="hlt">Clouds</span> cover roughly two thirds of the globe and act as an important regulator of Earth's radiation budget. Of these, multilayered <span class="hlt">clouds</span> occur about half of the time and are predominantly two-<span class="hlt">layered</span>. Changes in <span class="hlt">cloud</span> top height (CTH) have been predicted by models to have a globally averaged positive feedback, however observational changes in CTH have shown uncertain results. Additional CTH observations are necessary to better and quantify the effect. Improved CTH observations will also allow for improved sub-grid parameterizations in large-scale models and accurate CTH information is important when studying variations in freezing point and <span class="hlt">cloud</span> microphysics. NASA's airborne Research Scanning Polarimeter (RSP) is able to measure <span class="hlt">cloud</span> top height using a novel multi-angular contrast approach. RSP scans along the aircraft track and obtains measurements at 152 viewing angles at any aircraft location. The approach presented here aggregates measurements from multiple scans to a single location at <span class="hlt">cloud</span> altitude using a correlation function designed to identify the location-distinct features in each scan. During NASAs SEAC4RS air campaign, the RSP was mounted on the ER-2 aircraft along with the <span class="hlt">Cloud</span> Physics Lidar (CPL), which made simultaneous measurements of CTH. The RSPs unique method of determining CTH is presented. The capabilities of using single and combinations of channels within the approach are investigated. A detailed comparison of RSP retrieved CTHs with those of CPL reveal the accuracy of the approach. Results indicate a strong ability for the RSP to accurately identify <span class="hlt">cloud</span> heights. Interestingly, the analysis reveals an ability for the approach to identify multiple <span class="hlt">cloud</span> <span class="hlt">layers</span> in a single scene and estimate the CTH of each <span class="hlt">layer</span>. Capabilities and limitations of identifying single and multiple <span class="hlt">cloud</span> <span class="hlt">layers</span> heights are explored. Special focus is given to sources of error in the method including optically thin <span class="hlt">clouds</span>, physically thick <span class="hlt">clouds</span>, multi-<span class="hlt">layered</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/1376888-aerosol-cloud-microphysics-covariability-northeast-pacific-boundary-layer-estimated-ship-based-satellite-remote-sensing-observations-ne-pacific-aerosol-cloud-interactions','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/1376888-aerosol-cloud-microphysics-covariability-northeast-pacific-boundary-layer-estimated-ship-based-satellite-remote-sensing-observations-ne-pacific-aerosol-cloud-interactions"><span>Aerosol and <span class="hlt">cloud</span> microphysics covariability in the northeast Pacific boundary <span class="hlt">layer</span> estimated with ship-based and satellite remote sensing observations: NE Pacific Aerosol-<span class="hlt">Cloud</span> Interactions</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Painemal, David; Chiu, J. -Y. Christine; Minnis, Patrick</p> <p></p> <p>Ship measurements collected over the northeast Pacific along transects between the port of Los Angeles (33.7°N, 118.2°W) and Honolulu (21.3°N, 157.8°W) during May to August 2013 were utilized to investigate the covariability between marine low <span class="hlt">cloud</span> microphysical and aerosol properties. Ship-based retrievals of <span class="hlt">cloud</span> optical depth (τ) from a Sun photometer and liquid water path (LWP) from a microwave radiometer were combined to derive <span class="hlt">cloud</span> droplet number concentration Nd and compute a <span class="hlt">cloud</span>-aerosol interaction (ACI) metric defined as ACICCN = ∂ ln(Nd)/∂ ln(CCN), with CCN denoting the <span class="hlt">cloud</span> condensation nuclei concentration measured at 0.4% (CCN0.4) and 0.3% (CCN0.3) supersaturation. Analysismore » of CCN0.4, accumulation mode aerosol concentration (Na), and extinction coefficient (σext) indicates that Na and σext can be used as CCN0.4 proxies for estimating ACI. ACICCN derived from 10 min averaged Nd and CCN0.4 and CCN0.3, and CCN0.4 regressions using Na and σext, produce high ACICCN: near 1.0, that is, a fractional change in aerosols is associated with an equivalent fractional change in Nd. ACICCN computed in deep boundary <span class="hlt">layers</span> was small (ACICCN = 0.60), indicating that surface aerosol measurements inadequately represent the aerosol variability below <span class="hlt">clouds</span>. Satellite <span class="hlt">cloud</span> retrievals from MODerate-resolution Imaging Spectroradiometer and GOES-15 data were compared against ship-based retrievals and further analyzed to compute a satellite-based ACICCN. Satellite data correlated well with their ship-based counterparts with linear correlation coefficients equal to or greater than 0.78. Combined satellite Nd and ship-based CCN0.4 and Na yielded a maximum ACICCN = 0.88–0.92, a value slightly less than the ship-based ACICCN, but still consistent with aircraft-based studies in the eastern Pacific.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JGRD..123.3704M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JGRD..123.3704M"><span>Characteristic Vertical Profiles of <span class="hlt">Cloud</span> Water Composition in Marine Stratocumulus <span class="hlt">Clouds</span> and Relationships With Precipitation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>MacDonald, Alexander B.; Dadashazar, Hossein; Chuang, Patrick Y.; Crosbie, Ewan; Wang, Hailong; Wang, Zhen; Jonsson, Haflidi H.; Flagan, Richard C.; Seinfeld, John H.; Sorooshian, Armin</p> <p>2018-04-01</p> <p>This study uses airborne <span class="hlt">cloud</span> water composition measurements to characterize the vertical structure of air-equivalent mass concentrations of water-soluble species in marine stratocumulus <span class="hlt">clouds</span> off the California coast. A total of 385 <span class="hlt">cloud</span> water samples were collected in the months of July and August between 2011 and 2016 and analyzed for water-soluble ionic and elemental composition. Three characteristic profiles emerge: (i) a reduction of concentration with in-<span class="hlt">cloud</span> altitude for particulate species directly emitted from sources below <span class="hlt">cloud</span> without in-<span class="hlt">cloud</span> sources (e.g., Cl- and Na+), (ii) an increase of concentration with in-<span class="hlt">cloud</span> altitude (e.g., NO2- and formate), and (iii) species exhibiting a peak in concentration in the <span class="hlt">middle</span> of <span class="hlt">cloud</span> (e.g., non-sea-salt SO42-, NO3-, and organic acids). Vertical profiles of rainout parameters such as loss frequency, lifetime, and change in concentration with respect to time show that the scavenging efficiency throughout the <span class="hlt">cloud</span> depth depends strongly on the thickness of the <span class="hlt">cloud</span>. Thin <span class="hlt">clouds</span> exhibit a greater scavenging loss frequency at <span class="hlt">cloud</span> top, while thick <span class="hlt">clouds</span> have a greater scavenging loss frequency at <span class="hlt">cloud</span> base. The implications of these results for treatment of wet scavenging in models are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/1439004-characteristic-vertical-profiles-cloud-water-composition-marine-stratocumulus-clouds-relationships-precipitation','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/1439004-characteristic-vertical-profiles-cloud-water-composition-marine-stratocumulus-clouds-relationships-precipitation"><span>Characteristic Vertical Profiles of <span class="hlt">Cloud</span> Water Composition in Marine Stratocumulus <span class="hlt">Clouds</span> and Relationships With Precipitation</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>MacDonald, Alexander B.; Dadashazar, Hossein; Chuang, Patrick Y.</p> <p></p> <p>This study uses airborne <span class="hlt">cloud</span> water composition measurements to characterize the vertical structure of air-equivalent mass concentrations of water-soluble species in marine stratocumulus <span class="hlt">clouds</span> off the California coast. A total of 385 <span class="hlt">cloud</span> water samples were collected in the months of July and August between 2011 and 2016 and analyzed for water-soluble ionic and elemental composition. Three characteristic profiles emerge: (i) a reduction of concentration with in-<span class="hlt">cloud</span> altitude for particulate species directly emitted from sources below <span class="hlt">cloud</span> without in-<span class="hlt">cloud</span> sources (e.g., Cl-, Na+); (ii) an increase of concentration with in-<span class="hlt">cloud</span> altitude (e.g., NO2-, formate); and (iii) species exhibiting a peakmore » in concentration in the <span class="hlt">middle</span> of <span class="hlt">cloud</span> (e.g., non-sea salt SO42-, NO3-, organic acids). Vertical profiles of rainout parameters such as loss frequency, lifetime, and change in concentration with respect to time show that the scavenging efficiency throughout the <span class="hlt">cloud</span> depth depends strongly on the thickness of the <span class="hlt">cloud</span>. Thin <span class="hlt">clouds</span> exhibit a greater scavenging loss frequency at <span class="hlt">cloud</span> top, while thick <span class="hlt">clouds</span> have a greater scavenging loss frequency at <span class="hlt">cloud</span> base. The implications of these results for treatment of wet scavenging in models are discussed.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20160010516','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20160010516"><span>Progress in Understanding the Impacts of 3-D <span class="hlt">Cloud</span> Structure on MODIS <span class="hlt">Cloud</span> Property Retrievals for Marine Boundary <span class="hlt">Layer</span> <span class="hlt">Clouds</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Zhang, Zhibo; Werner, Frank; Miller, Daniel; Platnick, Steven; Ackerman, Andrew; DiGirolamo, Larry; Meyer, Kerry; Marshak, Alexander; Wind, Galina; Zhao, Guangyu</p> <p>2016-01-01</p> <p>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 <span class="hlt">cloud</span> vertical structure influences MODIS LWP retrievals. (Miller et al. 2016). Observation: Analysis of failed MODIS <span class="hlt">cloud</span> property retrievals. (Cho et al. 2015). <span class="hlt">Cloud</span> property retrievals from 15m resolution ASTER observations. (Werner et al. 2016). Modeling: LES-Satellite observation simulator (Zhang et al. 2012, Miller et al. 2016).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ACP....16.8643J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ACP....16.8643J"><span>Aerosols, <span class="hlt">clouds</span>, and precipitation in the North Atlantic trades observed during the Barbados aerosol <span class="hlt">cloud</span> experiment - Part 1: Distributions and variability</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jung, Eunsil; Albrecht, Bruce A.; Feingold, Graham; Jonsson, Haflidi H.; Chuang, Patrick; Donaher, Shaunna L.</p> <p>2016-07-01</p> <p>Shallow marine cumulus <span class="hlt">clouds</span> are by far the most frequently observed <span class="hlt">cloud</span> type over the Earth's oceans; but they are poorly understood and have not been investigated as extensively as stratocumulus <span class="hlt">clouds</span>. This study describes and discusses the properties and variations of aerosol, <span class="hlt">cloud</span>, and precipitation associated with shallow marine cumulus <span class="hlt">clouds</span> observed in the North Atlantic trades during a field campaign (Barbados Aerosol <span class="hlt">Cloud</span> Experiment- BACEX, March-April 2010), which took place off Barbados where African dust periodically affects the region. The principal observing platform was the Center for Interdisciplinary Remotely Piloted Aircraft Studies (CIRPAS) Twin Otter (TO) research aircraft, which was equipped with standard meteorological instruments, a zenith pointing <span class="hlt">cloud</span> radar and probes that measured aerosol, <span class="hlt">cloud</span>, and precipitation characteristics.The temporal variation and vertical distribution of aerosols observed from the 15 flights, which included the most intense African dust event during all of 2010 in Barbados, showed a wide range of aerosol conditions. During dusty periods, aerosol concentrations increased substantially in the size range between 0.5 and 10 µm (diameter), particles that are large enough to be effective giant <span class="hlt">cloud</span> condensation nuclei (CCN). The 10-day back trajectories showed three distinct air masses with distinct vertical structures associated with air masses originating in the Atlantic (typical maritime air mass with relatively low aerosol concentrations in the marine boundary <span class="hlt">layer</span>), Africa (Saharan air <span class="hlt">layer</span>), and mid-latitudes (continental pollution plumes). Despite the large differences in the total mass loading and the origin of the aerosols, the overall shapes of the aerosol particle size distributions were consistent, with the exception of the transition period.The TO was able to sample many <span class="hlt">clouds</span> at various phases of growth. Maximum <span class="hlt">cloud</span> depth observed was less than ˜ 3 km, while most <span class="hlt">clouds</span> were less than 1 km</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19860018365','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19860018365"><span>A model for the estimation of the surface fluxes of momentum, heat and moisture of the <span class="hlt">cloud</span> topped marine atmospheric boundary <span class="hlt">layer</span> from satellite measurable parameters. M.S. Thesis</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Allison, D. E.</p> <p>1984-01-01</p> <p>A model is developed for the estimation of the surface fluxes of momentum, heat, and moisture of the <span class="hlt">cloud</span> topped marine atmospheric boundary <span class="hlt">layer</span> by use of satellite remotely sensed parameters. The parameters chosen for the problem are the integrated liquid water content, q sub li, the integrated water vapor content, q sub vi, the <span class="hlt">cloud</span> top temperature, and either a measure of the 10 meter neutral wind speed or the friction velocity at the surface. Under the assumption of a horizontally homogeneous, well-mixed boundary <span class="hlt">layer</span>, the model calculates the equivalent potential temperature and total water profiles of the boundary <span class="hlt">layer</span> along with the boundary <span class="hlt">layer</span> height from inputs of q sub li, q sub vi, and <span class="hlt">cloud</span> top temperature. These values, along with the 10m neutral wind speed or friction velocity and the sea surface temperature are then used to estimate the surface fluxes. The development of a scheme to parameterize the integrated water vapor outside of the boundary <span class="hlt">layer</span> for the cases of cold air outbreak and California coastal stratus is presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSM11G..05P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSM11G..05P"><span>Altitude-dependent Drift of a Chemical Release <span class="hlt">Cloud</span> at <span class="hlt">Middle</span> Latitudes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pedersen, T.; Holmes, J. M.; Sutton, E. K.</p> <p>2017-12-01</p> <p>A chemical release experiment conducted at the White Sands Missile Range in February 2015 consisted of firing of three identical canisters at different altitudes along a near-vertical trajectory, creating a large structured <span class="hlt">cloud</span> after diffusion and expansion of the three initial dispersals. Dedicated optical observations from near the launch site and a remote site allow determination of the position and motion of the extended optical <span class="hlt">cloud</span> as a function of time, while photographs captured and posted by members of the general public provide additional look angles to constrain the <span class="hlt">cloud</span> shape in more detail. We compare the observed drift and evolution of the <span class="hlt">cloud</span> with empirical and theoretical models of the neutral winds to examine the altitudinal shear in the neutral winds and their effects on the motion and shape of the extended optical <span class="hlt">cloud</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29637042','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29637042"><span>The impact of <span class="hlt">cloud</span> vertical profile on liquid water path retrieval based on the bispectral method: A theoretical study based on large-eddy simulations of shallow marine boundary <span class="hlt">layer</span> <span class="hlt">clouds</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Miller, Daniel J; Zhang, Zhibo; Ackerman, Andrew S; Platnick, Steven; Baum, Bryan A</p> <p>2016-04-27</p> <p>Passive optical retrievals of <span class="hlt">cloud</span> liquid water path (LWP), like those implemented for Moderate Resolution Imaging Spectroradiometer (MODIS), rely on <span class="hlt">cloud</span> vertical profile assumptions to relate optical thickness ( τ ) and effective radius ( r e ) retrievals to LWP. These techniques typically assume that shallow <span class="hlt">clouds</span> are vertically homogeneous; however, an adiabatic <span class="hlt">cloud</span> model is plausibly more realistic for shallow marine boundary <span class="hlt">layer</span> <span class="hlt">cloud</span> regimes. In this study a satellite retrieval simulator is used to perform MODIS-like satellite retrievals, which in turn are compared directly to the large-eddy simulation (LES) output. This satellite simulator creates a framework for rigorous quantification of the impact that vertical profile features have on LWP retrievals, and it accomplishes this while also avoiding sources of bias present in previous observational studies. The <span class="hlt">cloud</span> vertical profiles from the LES are often more complex than either of the two standard assumptions, and the favored assumption was found to be sensitive to <span class="hlt">cloud</span> regime (cumuliform/stratiform). Confirming previous studies, drizzle and <span class="hlt">cloud</span> top entrainment of dry air are identified as physical features that bias LWP retrievals away from adiabatic and toward homogeneous assumptions. The mean bias induced by drizzle-influenced profiles was shown to be on the order of 5-10 g/m 2 . In contrast, the influence of <span class="hlt">cloud</span> top entrainment was found to be smaller by about a factor of 2. A theoretical framework is developed to explain variability in LWP retrievals by introducing modifications to the adiabatic r e profile. In addition to analyzing bispectral retrievals, we also compare results with the vertical profile sensitivity of passive polarimetric retrieval techniques.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5889945','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5889945"><span>The impact of <span class="hlt">cloud</span> vertical profile on liquid water path retrieval based on the bispectral method: A theoretical study based on large-eddy simulations of shallow marine boundary <span class="hlt">layer</span> <span class="hlt">clouds</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Miller, Daniel J.; Zhang, Zhibo; Ackerman, Andrew S.; Platnick, Steven; Baum, Bryan A.</p> <p>2018-01-01</p> <p>Passive optical retrievals of <span class="hlt">cloud</span> liquid water path (LWP), like those implemented for Moderate Resolution Imaging Spectroradiometer (MODIS), rely on <span class="hlt">cloud</span> vertical profile assumptions to relate optical thickness (τ) and effective radius (re) retrievals to LWP. These techniques typically assume that shallow <span class="hlt">clouds</span> are vertically homogeneous; however, an adiabatic <span class="hlt">cloud</span> model is plausibly more realistic for shallow marine boundary <span class="hlt">layer</span> <span class="hlt">cloud</span> regimes. In this study a satellite retrieval simulator is used to perform MODIS-like satellite retrievals, which in turn are compared directly to the large-eddy simulation (LES) output. This satellite simulator creates a framework for rigorous quantification of the impact that vertical profile features have on LWP retrievals, and it accomplishes this while also avoiding sources of bias present in previous observational studies. The <span class="hlt">cloud</span> vertical profiles from the LES are often more complex than either of the two standard assumptions, and the favored assumption was found to be sensitive to <span class="hlt">cloud</span> regime (cumuliform/stratiform). Confirming previous studies, drizzle and <span class="hlt">cloud</span> top entrainment of dry air are identified as physical features that bias LWP retrievals away from adiabatic and toward homogeneous assumptions. The mean bias induced by drizzle-influenced profiles was shown to be on the order of 5–10 g/m2. In contrast, the influence of <span class="hlt">cloud</span> top entrainment was found to be smaller by about a factor of 2. A theoretical framework is developed to explain variability in LWP retrievals by introducing modifications to the adiabatic re profile. In addition to analyzing bispectral retrievals, we also compare results with the vertical profile sensitivity of passive polarimetric retrieval techniques. PMID:29637042</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.A44F..08S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.A44F..08S"><span>Top-down and Bottom-up aerosol-<span class="hlt">cloud</span>-closure: towards understanding sources of unvertainty in deriving <span class="hlt">cloud</span> radiative flux</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sanchez, K.; Roberts, G.; Calmer, R.; Nicoll, K.; Hashimshoni, E.; Rosenfeld, D.; Ovadnevaite, J.; Preissler, J.; Ceburnis, D.; O'Dowd, C. D. D.; Russell, L. M.</p> <p>2017-12-01</p> <p>Top-down and bottom-up aerosol-<span class="hlt">cloud</span> shortwave radiative flux closures were conducted at the Mace Head atmospheric research station in Galway, Ireland in August 2015. Instrument platforms include ground-based, unmanned aerial vehicles (UAV), and satellite measurements of aerosols, <span class="hlt">clouds</span> and meteorological variables. The ground-based and airborne measurements of aerosol size distributions and <span class="hlt">cloud</span> condensation nuclei (CCN) concentration were used to initiate a 1D microphysical aerosol-<span class="hlt">cloud</span> parcel model (ACPM). UAVs were equipped for a specific science mission, with an optical particle counter for aerosol distribution profiles, a <span class="hlt">cloud</span> sensor to measure <span class="hlt">cloud</span> extinction, or a 5-hole probe for 3D wind vectors. These are the first UAV measurements at Mace Head. ACPM simulations are compared to in-situ <span class="hlt">cloud</span> extinction measurements from UAVs to quantify closure in terms of <span class="hlt">cloud</span> shortwave radiative flux. Two out of seven cases exhibit sub-adiabatic vertical temperature profiles within the <span class="hlt">cloud</span>, which suggests that entrainment processes affect <span class="hlt">cloud</span> microphysical properties and lead to an overestimate of simulated <span class="hlt">cloud</span> shortwave radiative flux. Including an entrainment parameterization and explicitly calculating the entrainment fraction in the ACPM simulations both improved <span class="hlt">cloud</span>-top radiative closure. Entrainment reduced the difference between simulated and observation-derived <span class="hlt">cloud</span>-top shortwave radiative flux (δRF) by between 25 W m-2 and 60 W m-2. After accounting for entrainment, satellite-derived <span class="hlt">cloud</span> droplet number concentrations (CDNC) were within 30% of simulated CDNC. In cases with a well-mixed boundary <span class="hlt">layer</span>, δRF is no greater than 20 W m-2 after accounting for <span class="hlt">cloud</span>-top entrainment, and up to 50 W m-2 when entrainment is not taken into account. In cases with a decoupled boundary <span class="hlt">layer</span>, <span class="hlt">cloud</span> microphysical properties are inconsistent with ground-based aerosol measurements, as expected, and δRF is as high as 88 W m-2, even high (> 30 W m-2) after</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.A44F..08S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.A44F..08S"><span>Top-down and Bottom-up aerosol-<span class="hlt">cloud</span>-closure: towards understanding sources of unvertainty in deriving <span class="hlt">cloud</span> radiative flux</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sanchez, K.; Roberts, G.; Calmer, R.; Nicoll, K.; Hashimshoni, E.; Rosenfeld, D.; Ovadnevaite, J.; Preissler, J.; Ceburnis, D.; O'Dowd, C. D. D.; Russell, L. M.</p> <p>2016-12-01</p> <p>Top-down and bottom-up aerosol-<span class="hlt">cloud</span> shortwave radiative flux closures were conducted at the Mace Head atmospheric research station in Galway, Ireland in August 2015. Instrument platforms include ground-based, unmanned aerial vehicles (UAV), and satellite measurements of aerosols, <span class="hlt">clouds</span> and meteorological variables. The ground-based and airborne measurements of aerosol size distributions and <span class="hlt">cloud</span> condensation nuclei (CCN) concentration were used to initiate a 1D microphysical aerosol-<span class="hlt">cloud</span> parcel model (ACPM). UAVs were equipped for a specific science mission, with an optical particle counter for aerosol distribution profiles, a <span class="hlt">cloud</span> sensor to measure <span class="hlt">cloud</span> extinction, or a 5-hole probe for 3D wind vectors. These are the first UAV measurements at Mace Head. ACPM simulations are compared to in-situ <span class="hlt">cloud</span> extinction measurements from UAVs to quantify closure in terms of <span class="hlt">cloud</span> shortwave radiative flux. Two out of seven cases exhibit sub-adiabatic vertical temperature profiles within the <span class="hlt">cloud</span>, which suggests that entrainment processes affect <span class="hlt">cloud</span> microphysical properties and lead to an overestimate of simulated <span class="hlt">cloud</span> shortwave radiative flux. Including an entrainment parameterization and explicitly calculating the entrainment fraction in the ACPM simulations both improved <span class="hlt">cloud</span>-top radiative closure. Entrainment reduced the difference between simulated and observation-derived <span class="hlt">cloud</span>-top shortwave radiative flux (δRF) by between 25 W m-2 and 60 W m-2. After accounting for entrainment, satellite-derived <span class="hlt">cloud</span> droplet number concentrations (CDNC) were within 30% of simulated CDNC. In cases with a well-mixed boundary <span class="hlt">layer</span>, δRF is no greater than 20 W m-2 after accounting for <span class="hlt">cloud</span>-top entrainment, and up to 50 W m-2 when entrainment is not taken into account. In cases with a decoupled boundary <span class="hlt">layer</span>, <span class="hlt">cloud</span> microphysical properties are inconsistent with ground-based aerosol measurements, as expected, and δRF is as high as 88 W m-2, even high (> 30 W m-2) after</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19950023935','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19950023935"><span>Extended field observations of cirrus <span class="hlt">clouds</span> using a ground-based <span class="hlt">cloud</span> observing system</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ackerman, Thomas P.</p> <p>1994-01-01</p> <p>The evolution of synoptic-scale dynamics associated with a <span class="hlt">middle</span> and upper tropospheric <span class="hlt">cloud</span> event that occurred on 26 November 1991 is examined. The case under consideration occurred during the FIRE CIRRUS-II Intensive Field Observing Period held in Coffeyville, KS during Nov. and Dec., 1991. Using data from the wind profiler demonstration network and a temporally and spatially augmented radiosonde array, emphasis is given to explaining the evolution of the kinematically-derived ageostrophic vertical circulations and correlating the circulation with the forcing of an extensively sampled <span class="hlt">cloud</span> field. This is facilitated by decomposing the horizontal divergence into its component parts through a natural coordinate representation of the flow. Ageostrophic vertical circulations are inferred and compared to the circulation forcing arising from geostrophic confluence and shearing deformation derived from the Sawyer-Eliassen Equation. It is found that a thermodynamically indirect vertical circulation existed in association with a jet streak exit region. The circulation was displaced to the cyclonic side of the jet axis due to the orientation of the jet exit between a deepening diffluent trough and building ridge. The <span class="hlt">cloud</span> line formed in the ascending branch of the vertical circulation with the most concentrated <span class="hlt">cloud</span> development occurring in conjunction with the maximum large-scale vertical motion. The relationship between the large scale dynamics and the parameterization of <span class="hlt">middle</span> and upper tropospheric <span class="hlt">clouds</span> in large-scale models is discussed and an example of ice water contents derived from a parameterization forced by the diagnosed vertical motions and observed water vapor contents is presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140011287','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140011287"><span>Estimating the Direct Radiative Effect of Absorbing Aerosols Overlying Marine Boundary <span class="hlt">Layer</span> <span class="hlt">Clouds</span> in the Southeast Atlantic Using MODIS and CALIOP</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Meyer, Kerry; Platnick, Steven; Oreopoulos, Lazaros; Lee, Dongmin</p> <p>2013-01-01</p> <p>Absorbing aerosols such as smoke strongly absorb solar radiation, particularly at ultraviolet and visible/near-infrared (VIS/NIR) wavelengths, and their presence above <span class="hlt">clouds</span> can have considerable implications. It has been previously shown that they have a positive (i.e., warming) direct aerosol radiative effect (DARE) when overlying bright <span class="hlt">clouds</span>. Additionally, they can cause biased passive instrument satellite retrievals in techniques that rely on VIS/NIR wavelengths for inferring the <span class="hlt">cloud</span> optical thickness (COT) and effective radius (re) of underlying <span class="hlt">clouds</span>, which can in turn yield biased above-<span class="hlt">cloud</span> DARE estimates. Here we investigate Moderate Resolution Imaging Spectroradiometer (MODIS) <span class="hlt">cloud</span> optical property retrieval biases due to overlying absorbing aerosols observed by <span class="hlt">Cloud</span>-Aerosol Lidar with Orthogonal Polarization (CALIOP) and examine the impact of these biases on above-<span class="hlt">cloud</span> DARE estimates. The investigation focuses on a region in the southeast Atlantic Ocean during August and September (2006-2011), where smoke from biomass burning in southern Africa overlies persistent marine boundary <span class="hlt">layer</span> stratocumulus <span class="hlt">clouds</span>. Adjusting for above-<span class="hlt">cloud</span> aerosol attenuation yields increases in the regional mean liquid COT (averaged over all ocean-only liquid <span class="hlt">clouds</span>) by roughly 6%; mean re increases by roughly 2.6%, almost exclusively due to the COT adjustment in the non-orthogonal retrieval space. It is found that these two biases lead to an underestimate of DARE. For liquid <span class="hlt">cloud</span> Aqua MODIS pixels with CALIOP-observed above-<span class="hlt">cloud</span> smoke, the regional mean above-<span class="hlt">cloud</span> radiative forcing efficiency (DARE per unit aerosol optical depth (AOD)) at time of observation (near local noon for Aqua overpass) increases from 50.9Wm(sup-2)AOD(sup-1) to 65.1Wm(sup-2)AOD(sup -1) when using bias-adjusted instead of nonadjusted MODIS <span class="hlt">cloud</span> retrievals.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120002602','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120002602"><span>Dispersion of the Volcanic Sulfate <span class="hlt">Cloud</span> from the Mount Pinatubo Eruption</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Aquila, Valentina; Oman, Luke D.; Stolarski, Richard S.; Colarco, Peter R.; Newman, Paul A.</p> <p>2012-01-01</p> <p>We simulate the transport of the volcanic <span class="hlt">cloud</span> from the 1991 eruption of Mount Pinatubo with the GEOS-5 general circulation model. Our simulations are in good agreement with observational data. We tested the importance of initial condition corresponding to the specific meteorological situation at the time of the eruption by employing reanalysis from MERRA. We found no significant difference in the transport of the <span class="hlt">cloud</span>. We show how the inclusion of the interaction between volcanic sulfate aerosol and radiation is essential for a reliable simulation of the transport of the volcanic <span class="hlt">cloud</span>. The absorption of long wave radiation by the volcanic sulfate induces a rising of the volcanic <span class="hlt">cloud</span> up to the <span class="hlt">middle</span> stratosphere, combined with divergent motion from the latitude of the eruption to the tropics. Our simulations indicate that the <span class="hlt">cloud</span> diffuses to the northern hemisphere through a lower stratospheric pathway, and to mid- and high latitudes of the southern hemisphere through a <span class="hlt">middle</span> stratospheric pathway, centered at about 30 hPa. The direction of the <span class="hlt">middle</span> stratospheric pathway depends on the season. We did not detect any significant change of the mixing between tropics and mid- and high latitudes in the southern hemisphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19950004648','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19950004648"><span>The daytime course of total ozone content caused by <span class="hlt">cloud</span> convection</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ishov, Alexander G.</p> <p>1994-01-01</p> <p>Presented are the experimental data on the daytime course of the total O3 and SO2 content obtained by Brewer 044 spectrophotometer in the tropics (Thumba, India, 8.53 N, 76.87 W, March-May 1990) and at <span class="hlt">middle</span> latitudes (Obninsk, Russia, 55.12 N, 36.6 W, May-October 1991) of the Northern Hemisphere. The analysis showed that under fine warm weather conditions without precipitation (air mass change and frontal passage were not observed during several days) in days with well-developed convective <span class="hlt">clouds</span> (cloudless morning, convective <span class="hlt">clouds</span> in the daytime, no <span class="hlt">clouds</span> in the evening) there is a typical nearly symmetric (with respect to local noon) course of the total O3 (with the minimum at about local noon) and SO2 (with the maximum at about local noon) content. The minimum depth is about 2-5 percent of the average daytime values of the total ozone content. The synchronous measurements of pressure pulsations with microbarograph (they are the indicator of convective and turbulent motion development in the lower subcloud atmospheric <span class="hlt">layer</span>) showed that during these days there is a nearly symmetric course of pressure pulsations with the maximum at about local noon.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA09910.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA09910.html"><span>Deep <span class="hlt">Clouds</span></span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2008-05-27</p> <p>Bright puffs and ribbons of <span class="hlt">cloud</span> drift lazily through Saturn's murky skies. In contrast to the bold red, orange and white <span class="hlt">clouds</span> of Jupiter, Saturn's <span class="hlt">clouds</span> are overlain by a thick <span class="hlt">layer</span> of haze. The visible <span class="hlt">cloud</span> tops on Saturn are deeper in its atmosphere due to the planet's cooler temperatures. This view looks toward the unilluminated side of the rings from about 18 degrees above the ringplane. Images taken using red, green and blue spectral filters were combined to create this natural color view. The images were acquired with the Cassini spacecraft wide-angle camera on April 15, 2008 at a distance of approximately 1.5 million kilometers (906,000 miles) from Saturn. Image scale is 84 kilometers (52 miles) per pixel. http://photojournal.jpl.nasa.gov/catalog/PIA09910</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.A22A..07R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.A22A..07R"><span>Using In Situ Observations and Satellite Retrievals to Constrain Large-Eddy Simulations and Single-Column Simulations: Implications for Boundary-<span class="hlt">Layer</span> <span class="hlt">Cloud</span> Parameterization in the NASA GISS GCM</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Remillard, J.</p> <p>2015-12-01</p> <p>Two low-<span class="hlt">cloud</span> periods from the CAP-MBL deployment of the ARM Mobile Facility at the Azores are selected through a cluster analysis of ISCCP <span class="hlt">cloud</span> property matrices, so as to represent two low-<span class="hlt">cloud</span> weather states that the GISS GCM severely underpredicts not only in that region but also globally. The two cases represent (1) shallow cumulus <span class="hlt">clouds</span> occurring in a cold-air outbreak behind a cold front, and (2) stratocumulus <span class="hlt">clouds</span> occurring when the region was dominated by a high-pressure system. Observations and MERRA reanalysis are used to derive specifications used for large-eddy simulations (LES) and single-column model (SCM) simulations. The LES captures the major differences in horizontal structure between the two low-<span class="hlt">cloud</span> fields, but there are unconstrained uncertainties in <span class="hlt">cloud</span> microphysics and challenges in reproducing W-band Doppler radar moments. The SCM run on the vertical grid used for CMIP-5 runs of the GCM does a poor job of representing the shallow cumulus case and is unable to maintain an overcast deck in the stratocumulus case, providing some clues regarding problems with low-<span class="hlt">cloud</span> representation in the GCM. SCM sensitivity tests with a finer vertical grid in the boundary <span class="hlt">layer</span> show substantial improvement in the representation of <span class="hlt">cloud</span> amount for both cases. GCM simulations with CMIP-5 versus finer vertical gridding in the boundary <span class="hlt">layer</span> are compared with observations. The adoption of a two-moment <span class="hlt">cloud</span> microphysics scheme in the GCM is also tested in this framework. The methodology followed in this study, with the process-based examination of different time and space scales in both models and observations, represents a prototype for GCM <span class="hlt">cloud</span> parameterization improvements.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRD..122.3492L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRD..122.3492L"><span>Evolution of trace elements in the planetary boundary <span class="hlt">layer</span> in southern China: Effects of dust storms and aerosol-<span class="hlt">cloud</span> interactions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Li, Tao; Wang, Yan; Zhou, Jie; Wang, Tao; Ding, Aijun; Nie, Wei; Xue, Likun; Wang, Xinfeng; Wang, Wenxing</p> <p>2017-03-01</p> <p>Aerosols and <span class="hlt">cloud</span> water were analyzed at a mountaintop in the planetary boundary <span class="hlt">layer</span> in southern China during March-May 2009, when two Asian dust storms occurred, to investigate the effects of aerosol-<span class="hlt">cloud</span> interactions (ACIs) on chemical evolution of atmospheric trace elements. Fe, Al, and Zn predominated in both coarse and fine aerosols, followed by high concentrations of toxic Pb, As, and Cd. Most of these aerosol trace elements, which were affected by dust storms, exhibited various increases in concentrations but consistent decreases in solubility. Zn, Fe, Al, and Pb were the most abundant trace elements in <span class="hlt">cloud</span> water. The trace element concentrations exhibited logarithmic inverse relationships with the <span class="hlt">cloud</span> liquid water content and were found highly pH dependent with minimum concentrations at the threshold of pH 5.0. The calculation of Visual MINTEQ model showed that 80.7-96.3% of Fe(II), Zn(II), Pb(II), and Cu(II) existed in divalent free ions, while 71.7% of Fe(III) and 71.5% of Al(III) were complexed by oxalate and fluoride, respectively. ACIs could markedly change the speciation distributions of trace elements in <span class="hlt">cloud</span> water by pH modification. The in-<span class="hlt">cloud</span> scavenging of aerosol trace elements likely reached a peak after the first 2-3 h of <span class="hlt">cloud</span> processing, with scavenging ratios between 0.12 for Cr and 0.57 for Pb. The increases of the trace element solubility (4-33%) were determined in both in-<span class="hlt">cloud</span> aerosols and postcloud aerosols. These results indicated the significant importance of aerosol-<span class="hlt">cloud</span> interactions to the evolution of trace elements during the first several <span class="hlt">cloud</span> condensation/evaporation cycles.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_13 --> <div id="page_14" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="261"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20070021462','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20070021462"><span>The Influence of Aerosols on the Shortwave <span class="hlt">Cloud</span> Radiative Forcing from North Pacific Oceanic <span class="hlt">Clouds</span>: Results from the <span class="hlt">Cloud</span> Indirect Forcing Experiment (CIFEX)</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wilcox, Eric M.; Roberts, Greg; Ramanathan, V.</p> <p>2006-01-01</p> <p>Aerosols over the Northeastern Pacific Ocean enhance the <span class="hlt">cloud</span> drop number concentration and reduce the drop size for marine stratocumulus and cumulus <span class="hlt">clouds</span>. These microphysical effects result in brighter <span class="hlt">clouds</span>, as evidenced by a combination of aircraft and satellite observations. In-situ measurements from the <span class="hlt">Cloud</span> Indirect Forcing Experiment (CIFEX) indicate that the mean <span class="hlt">cloud</span> drop number concentration in low <span class="hlt">clouds</span> over the polluted marine boundary <span class="hlt">layer</span> is greater by 53/cu cm compared to clean <span class="hlt">clouds</span>, and the mean <span class="hlt">cloud</span> drop effective radius is smaller by 4 microns. We link these in-situ measurements of <span class="hlt">cloud</span> modification by aerosols, for the first time, with collocated satellite broadband radiative flux observations from the <span class="hlt">Clouds</span> and the Earth's Radiant Energy System (CERES) to show that these microphysical effects of aerosols enhance the top-of-atmosphere cooling by -9.9+/-4.3 W/sq m for overcast conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018AMT....11..593C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018AMT....11..593C"><span>All-sky photogrammetry techniques to georeference a <span class="hlt">cloud</span> field</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Crispel, Pierre; Roberts, Gregory</p> <p>2018-01-01</p> <p>In this study, we present a novel method of identifying and geolocalizing <span class="hlt">cloud</span> field elements from a portable all-sky camera stereo network based on the ground and oriented towards zenith. The methodology is mainly based on stereophotogrammetry which is a 3-D reconstruction technique based on triangulation from corresponding stereo pixels in rectified images. In cases where <span class="hlt">clouds</span> are horizontally separated, identifying individual positions is performed with segmentation techniques based on hue filtering and contour detection algorithms. Macroscopic <span class="hlt">cloud</span> field characteristics such as <span class="hlt">cloud</span> <span class="hlt">layer</span> base heights and velocity fields are also deduced. In addition, the methodology is fitted to the context of measurement campaigns which impose simplicity of implementation, auto-calibration, and portability. Camera internal geometry models are achieved a priori in the laboratory and validated to ensure a certain accuracy in the peripheral parts of the all-sky image. Then, stereophotogrammetry with dense 3-D reconstruction is applied with cameras spaced 150 m apart for two validation cases. The first validation case is carried out with cumulus <span class="hlt">clouds</span> having a <span class="hlt">cloud</span> base height at 1500 m a.g.l. The second validation case is carried out with two <span class="hlt">cloud</span> <span class="hlt">layers</span>: a cumulus fractus <span class="hlt">layer</span> with a base height at 1000 m a.g.l. and an altocumulus stratiformis <span class="hlt">layer</span> with a base height of 2300 m a.g.l. Velocity fields at <span class="hlt">cloud</span> base are computed by tracking image rectangular patterns through successive shots. The height uncertainty is estimated by comparison with a Vaisala CL31 ceilometer located on the site. The uncertainty on the horizontal coordinates and on the velocity field are theoretically quantified by using the experimental uncertainties of the <span class="hlt">cloud</span> base height and camera orientation. In the first cumulus case, segmentation of the image is performed to identify individuals <span class="hlt">clouds</span> in the <span class="hlt">cloud</span> field and determine the horizontal positions of the <span class="hlt">cloud</span> centers.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1210106-photolysis-rates-correlated-overlapping-cloud-fields-cloud','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1210106-photolysis-rates-correlated-overlapping-cloud-fields-cloud"><span>Photolysis rates in correlated overlapping <span class="hlt">cloud</span> fields: <span class="hlt">Cloud</span>-J 7.3c</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Prather, M. J.</p> <p>2015-08-14</p> <p>A new approach for modeling photolysis rates ( J values) in atmospheres with fractional <span class="hlt">cloud</span> cover has been developed and is implemented as <span class="hlt">Cloud</span>-J – a multi-scattering eight-stream radiative transfer model for solar radiation based on Fast-J. Using observations of the vertical correlation of <span class="hlt">cloud</span> <span class="hlt">layers</span>, <span class="hlt">Cloud</span>-J 7.3c provides a practical and accurate method for modeling atmospheric chemistry. The combination of the new maximum-correlated <span class="hlt">cloud</span> groups with the integration over all <span class="hlt">cloud</span> combinations by four quadrature atmospheres produces mean J values in an atmospheric column with root mean square (rms) errors of 4 % or less compared with 10–20 %more » errors using simpler approximations. <span class="hlt">Cloud</span>-J is practical for chemistry–climate models, requiring only an average of 2.8 Fast-J calls per atmosphere vs. hundreds of calls with the correlated <span class="hlt">cloud</span> groups, or 1 call with the simplest <span class="hlt">cloud</span> approximations. Another improvement in modeling J values, the treatment of volatile organic compounds with pressure-dependent cross sections, is also incorporated into <span class="hlt">Cloud</span>-J.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001JGR...106.5335H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001JGR...106.5335H"><span>UV 380 nm reflectivity of the Earth's surface, <span class="hlt">clouds</span> and aerosols</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Herman, J. R.; Celarier, E.; Larko, D.</p> <p>2001-03-01</p> <p>The 380 nm radiance measurements of the Total Ozone Mapping Spectrometer (TOMS) have been converted into a global data set of daily (1979-1992) Lambert equivalent reflectivities R of the Earth's surface and boundary <span class="hlt">layer</span> (<span class="hlt">clouds</span>, aerosols, surface haze, and snow/ice) and then corrected to RPC for the presence of partly <span class="hlt">clouded</span> scenes. Since UV surface reflectivity is between 2 and 8% for both land and water during all seasons of the year (except for ice and snow cover), reflectivities larger than the surface value indicate the presence of <span class="hlt">clouds</span>, haze, or aerosols in the satellite field of view. A statistical analysis of 14 years of daily reflectivity data shows that most snow-/ice-free scenes observed by TOMS have a reflectivity less than 10% for the majority of days during a year. The 380 nm reflectivity data show that the true surface reflectivity is 2-3% lower than the most frequently occurring reflectivity value for each TOMS scene as seen from space. Most likely the cause is a combination of frequently occurring boundary <span class="hlt">layer</span> water and/or aerosol haze. For most regions the observation of extremely clear conditions needed to estimate the surface reflectivity from space is a comparatively rare occurrence. Certain areas (e.g., Australia, southern Africa, portions of northern Africa) are <span class="hlt">cloud</span>-free more than 80% of the year, which exposes these regions to larger amounts of UV radiation than at comparable latitudes in the Northern Hemisphere. Regions over rain forests, jungle areas, Europe and Russia, the bands surrounding the Arctic and Antarctic regions, and many ocean areas have significant <span class="hlt">cloud</span> cover (R>15%) more than half of each year. In the low to <span class="hlt">middle</span> latitudes the areas with the heaviest <span class="hlt">cloud</span> cover (highest reflectivity for most of the year) are the forest areas of northern South America, southern Central America, the jungle areas of equatorial Africa, and high mountain regions such as the Himalayas or the Andes. The TOMS reflectivity data show both</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018ThApC.131.1465W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018ThApC.131.1465W"><span>Can CFMIP2 models reproduce the leading modes of <span class="hlt">cloud</span> vertical structure in the CALIPSO-GOCCP observations?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Fang; Yang, Song</p> <p>2018-02-01</p> <p>Using principal component (PC) analysis, three leading modes of <span class="hlt">cloud</span> vertical structure (CVS) are revealed by the GCM-Oriented CALIPSO <span class="hlt">Cloud</span> Product (GOCCP), i.e. tropical high, subtropical anticyclonic and extratropical cyclonic <span class="hlt">cloud</span> modes (THCM, SACM and ECCM, respectively). THCM mainly reflect the contrast between tropical high <span class="hlt">clouds</span> and <span class="hlt">clouds</span> in <span class="hlt">middle</span>/high latitudes. SACM is closely associated with <span class="hlt">middle</span>-high <span class="hlt">clouds</span> in tropical convective cores, few-<span class="hlt">cloud</span> regimes in subtropical anticyclonic <span class="hlt">clouds</span> and stratocumulus over subtropical eastern oceans. ECCM mainly corresponds to <span class="hlt">clouds</span> along extratropical cyclonic regions. Models of phase 2 of <span class="hlt">Cloud</span> Feedback Model Intercomparison Project (CFMIP2) well reproduce the THCM, but SACM and ECCM are generally poorly simulated compared to GOCCP. Standardized PCs corresponding to CVS modes are generally captured, whereas original PCs (OPCs) are consistently underestimated (overestimated) for THCM (SACM and ECCM) by CFMIP2 models. The effects of CVS modes on relative <span class="hlt">cloud</span> radiative forcing (RSCRF/RLCRF) (RSCRF being calculated at the surface while RLCRF at the top of atmosphere) are studied in terms of principal component regression method. Results show that CFMIP2 models tend to overestimate (underestimated or simulate the opposite sign) RSCRF/RLCRF radiative effects (REs) of ECCM (THCM and SACM) in unit global mean OPC compared to observations. These RE biases may be attributed to two factors, one of which is underestimation (overestimation) of low/<span class="hlt">middle</span> <span class="hlt">clouds</span> (high <span class="hlt">clouds</span>) (also known as stronger (weaker) REs in unit low/<span class="hlt">middle</span> (high) <span class="hlt">clouds</span>) in simulated global mean <span class="hlt">cloud</span> profiles, the other is eigenvector biases in CVS modes (especially for SACM and ECCM). It is suggested that much more attention should be paid on improvement of CVS, especially <span class="hlt">cloud</span> parameterization associated with particular physical processes (e.g. downwelling regimes with the Hadley circulation, extratropical storm tracks and others), which</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.A33N..06S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.A33N..06S"><span>On the existence of tropical anvil <span class="hlt">clouds</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Seeley, J.; Jeevanjee, N.; Langhans, W.; Romps, D.</p> <p>2017-12-01</p> <p>In the deep tropics, extensive anvil <span class="hlt">clouds</span> produce a peak in <span class="hlt">cloud</span> cover below the tropopause. The dominant paradigm for <span class="hlt">cloud</span> cover attributes this anvil peak to a <span class="hlt">layer</span> of enhanced mass convergence in the clear-sky upper-troposphere, which is presumed to force frequent detrainment of convective anvils. However, <span class="hlt">cloud</span> cover also depends on the lifetime of cloudy air after it detrains, which raises the possibility that anvil <span class="hlt">clouds</span> may be the signature of slow <span class="hlt">cloud</span> decay rather than enhanced detrainment. Here we measure the <span class="hlt">cloud</span> decay timescale in <span class="hlt">cloud</span>-resolving simulations, and find that cloudy updrafts that detrain in the upper troposphere take much longer to dissipate than their shallower counterparts. We show that <span class="hlt">cloud</span> lifetimes are long in the upper troposphere because the saturation specific humidity becomes orders of magnitude smaller than the typical condensed water loading of cloudy updrafts. This causes evaporative <span class="hlt">cloud</span> decay to act extremely slowly, thereby prolonging <span class="hlt">cloud</span> lifetimes in the upper troposphere. As a consequence, extensive anvil <span class="hlt">clouds</span> still occur in a convecting atmosphere that is forced to have no preferential clear-sky convergence <span class="hlt">layer</span>. On the other hand, when <span class="hlt">cloud</span> lifetimes are fixed at a characteristic lower-tropospheric value, extensive anvil <span class="hlt">clouds</span> do not form. Our results support a revised understanding of tropical anvil <span class="hlt">clouds</span>, which attributes their existence to the microphysics of slow <span class="hlt">cloud</span> decay rather than a peak in clear-sky convergence.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19980019502','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19980019502"><span><span class="hlt">Cloud</span> Radiation Forcings and Feedbacks: General Circulation Model Tests and Observational Validation</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lee,Wan-Ho; Iacobellis, Sam F.; Somerville, Richard C. J.</p> <p>1997-01-01</p> <p>Using an atmospheric general circulation model (the National Center for Atmospheric Research Community Climate Model: CCM2), the effects on climate sensitivity of several different <span class="hlt">cloud</span> radiation parameterizations have been investigated. In addition to the original <span class="hlt">cloud</span> radiation scheme of CCM2, four parameterizations incorporating prognostic <span class="hlt">cloud</span> water were tested: one version with prescribed <span class="hlt">cloud</span> radiative properties and three other versions with interactive <span class="hlt">cloud</span> radiative properties. The authors' numerical experiments employ perpetual July integrations driven by globally constant sea surface temperature forcings of two degrees, both positive and negative. A diagnostic radiation calculation has been applied to investigate the partial contributions of high, <span class="hlt">middle</span>, and low <span class="hlt">cloud</span> to the total <span class="hlt">cloud</span> radiative forcing, as well as the contributions of water vapor, temperature, and <span class="hlt">cloud</span> to the net climate feedback. The high <span class="hlt">cloud</span> net radiative forcing is positive, and the <span class="hlt">middle</span> and low <span class="hlt">cloud</span> net radiative forcings are negative. The total net <span class="hlt">cloud</span> forcing is negative in all of the model versions. The effect of interactive <span class="hlt">cloud</span> radiative properties on global climate sensitivity is significant. The net <span class="hlt">cloud</span> radiative feedbacks consist of quite different shortwave and longwave components between the schemes with interactive <span class="hlt">cloud</span> radiative properties and the schemes with specified properties. The increase in <span class="hlt">cloud</span> water content in the warmer climate leads to optically thicker <span class="hlt">middle</span>- and low-level <span class="hlt">clouds</span> and in turn to negative shortwave feedbacks for the interactive radiative schemes, while the decrease in <span class="hlt">cloud</span> amount simply produces a positive shortwave feedback for the schemes with a specified <span class="hlt">cloud</span> water path. For the longwave feedbacks, the decrease in high effective cloudiness for the schemes without interactive radiative properties leads to a negative feedback, while for the other cases, the longwave feedback is positive. These <span class="hlt">cloud</span> radiation</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20050180543','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20050180543"><span>Validation of AIRS/AMSU <span class="hlt">Cloud</span> Retrievals Using MODIS <span class="hlt">Cloud</span> Analyses</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Molnar, Gyula I.; Susskind, Joel</p> <p>2005-01-01</p> <p>The AIRS/AMSU (flying on the EOS-AQUA satellite) sounding retrieval methodology allows for the retrieval of key atmospheric/surface parameters under partially cloudy conditions (Susskind et al.). In addition, <span class="hlt">cloud</span> parameters are also derived from the AIRS/AMSU observations. Within each AIRS footprint, <span class="hlt">cloud</span> parameters at up to 2 <span class="hlt">cloud</span> <span class="hlt">layers</span> are determined with differing <span class="hlt">cloud</span> top pressures and effective (product of infrared emissivity at 11 microns and physical <span class="hlt">cloud</span> fraction) <span class="hlt">cloud</span> fractions. However, so far the AIRS <span class="hlt">cloud</span> product has not been rigorously evaluated/validated. Fortunately, collocated/coincident radiances measured by MODIS/AQUA (at a much lower spectral resolution but roughly an order of-magnitude higher spatial resolution than that of AIRS) are used to determine analogous <span class="hlt">cloud</span> products from MODIS. This allows us for a rather rare and interesting possibility: the intercomparisons and mutual validation of imager vs. sounder-based <span class="hlt">cloud</span> products obtained from the same satellite positions. First, we present results of small-scale (granules) instantaneous intercomparisons. Next, we will evaluate differences of temporally averaged (monthly) means as well as the representation of inter-annual variability of <span class="hlt">cloud</span> parameters as presented by the two <span class="hlt">cloud</span> data sets. In particular, we present statistical differences in the retrieved parameters of <span class="hlt">cloud</span> fraction and <span class="hlt">cloud</span> top pressure. We will investigate what type of <span class="hlt">cloud</span> systems are retrieved most consistently (if any) with both retrieval schemes, and attempt to assess reasons behind statistically significant differences.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70027681','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70027681"><span>The evolution of Titan's mid-latitude <span class="hlt">clouds</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Griffith, C.A.; Penteado, P.; Baines, K.; Drossart, P.; Barnes, J.; Bellucci, G.; Bibring, J.; Brown, R.; Buratti, B.; Capaccioni, F.; Cerroni, P.; Clark, R.; Combes, M.; Coradini, A.; Cruikshank, D.; Formisano, V.; Jaumann, R.; Langevin, Y.; Matson, D.; McCord, T.; Mennella, V.; Nelson, R.; Nicholson, P.; Sicardy, B.; Sotin, Christophe; Soderblom, L.A.; Kursinski, R.</p> <p>2005-01-01</p> <p>Spectra from Cassini's Visual and Infrared Mapping Spectrometer reveal that the horizontal structure, height, and optical depth of Titan's <span class="hlt">clouds</span> are highly, dynamic. Vigorous <span class="hlt">cloud</span> centers are seen to rise from the <span class="hlt">middle</span> to the upper troposphere within 30 minutes and dissipate within the next hour. Their development indicates that Titan's <span class="hlt">clouds</span> evolve convectively; dissipate through rain; and, over the next several hours, waft downwind to achieve their great longitude extents. These and other characteristics suggest that temperate <span class="hlt">clouds</span> originate from circulation-induced convergence, in addition to a forcing at the surface associated with Saturn's tides, geology, and/or surface composition.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA05391.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA05391.html"><span>Bands of <span class="hlt">Clouds</span> and Lace</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2004-05-13</p> <p>As Cassini nears its rendezvous with Saturn, new detail in the banded <span class="hlt">clouds</span> of the planet's atmosphere are becoming visible. Cassini began the journey to the ringed world of Saturn nearly seven years ago and is now less than two months away from orbit insertion on June 30. Cassini’s narrow-angle camera took this image on April 16, 2004, when the spacecraft was 38.5 million kilometers (23.9 million miles) from Saturn. Dark regions are generally areas free of high <span class="hlt">clouds</span>, and bright areas are places with high, thick <span class="hlt">clouds</span> which shield the view of the darker areas below. A dark spot is visible at the south pole, which is remarkable to scientists because it is so small and centered. The spot could be affected by Saturn's magnetic field, which is nearly aligned with the planet's rotation axis, unlike the magnetic fields of Jupiter and Earth. From south to north, other notable features are the two white spots just above the dark spot toward the right, and the large dark oblong-shaped feature that extends across the <span class="hlt">middle</span>. The darker band beneath the oblong-shaped feature has begun to show a lacy pattern of lighter-colored, high altitude <span class="hlt">clouds</span>, indicative of turbulent atmospheric conditions. The <span class="hlt">cloud</span> bands move at different speeds, and their irregularities may be due to either the different motions between them or to disturbances below the visible <span class="hlt">cloud</span> <span class="hlt">layer</span>. Such disturbances might be powered by the planet's internal heat; Saturn radiates more energy than it receives from the Sun. The moon Mimas (396 kilometers, 245 miles across) is visible to the left of the south pole. Saturn currently has 31 known moons. Since launch, 13 new moons have been discovered by ground-based telescopes. Cassini will get a closer look and may discover new moons, perhaps embedded within the planet’s magnificent rings. This image was taken using a filter sensitive to light near 727 nanometers, one of the near-infrared absorption bands of methane gas, which is one of the ingredients in</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004JApMe..43.1083L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004JApMe..43.1083L"><span>AIRS Subpixel <span class="hlt">Cloud</span> Characterization Using MODIS <span class="hlt">Cloud</span> Products.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Li, Jun; Menzel, W. Paul; Sun, Fengying; Schmit, Timothy J.; Gurka, James</p> <p>2004-08-01</p> <p>The Moderate Resolution Imaging Spectroradiometer (MODIS) and the Atmospheric Infrared Sounder (AIRS) measurements from the Earth Observing System's (EOS's) Aqua satellite enable improved global monitoring of the distribution of <span class="hlt">clouds</span>. MODIS is able to provide, at high spatial resolution (1 5 km), a <span class="hlt">cloud</span> mask, surface and <span class="hlt">cloud</span> types, <span class="hlt">cloud</span> phase, <span class="hlt">cloud</span>-top pressure (CTP), effective <span class="hlt">cloud</span> amount (ECA), <span class="hlt">cloud</span> particle size (CPS), and <span class="hlt">cloud</span> optical thickness (COT). AIRS is able to provide CTP, ECA, CPS, and COT at coarser spatial resolution (13.5 km at nadir) but with much better accuracy using its high-spectral-resolution measurements. The combined MODIS AIRS system offers the opportunity for improved <span class="hlt">cloud</span> products over those possible from either system alone. The key steps for synergistic use of imager and sounder radiance measurements are 1) collocation in space and time and 2) imager <span class="hlt">cloud</span> amount, type, and phase determination within the sounder pixel. The MODIS and AIRS measurements from the EOS Aqua satellite provide the opportunity to study the synergistic use of advanced imager and sounder measurements. As the first step, the MODIS classification procedure is applied to identify various surface and <span class="hlt">cloud</span> types within an AIRS footprint. <span class="hlt">Cloud-layer</span> information (lower, midlevel, or high <span class="hlt">clouds</span>) and phase information (water, ice, or mixed-phase <span class="hlt">clouds</span>) within the AIRS footprint are sorted and characterized using MODIS 1-km-spatial-resolution data. The combined MODIS and AIRS data for various scenes are analyzed to study the utility of the synergistic use of high-spatial-resolution imager products and high-spectral-resolution sounder radiance measurements. There is relevance to the optimal use of data from the Advanced Baseline Imager (ABI) and Hyperspectral Environmental Suite (HES) systems, which are to fly on the Geostationary Operational Environmental Satellite (GOES)-R.<HR ALIGN="center" WIDTH="30%"></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018Icar..302..360S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018Icar..302..360S"><span>Models of bright storm <span class="hlt">clouds</span> and related dark ovals in Saturn's Storm Alley as constrained by 2008 Cassini/VIMS spectra</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sromovsky, L. A.; Baines, K. H.; Fry, P. M.</p> <p>2018-03-01</p> <p>A 5° latitude band on Saturn centered near planetocentric latitude 36°S is known as "Storm Alley" because it has been for several extended periods a site of frequent lightning activity and associated thunderstorms, first identified by Porco et al. (2005). The thunderstorms appeared as bright <span class="hlt">clouds</span> at short and long continuum wavelengths, and over a period of a week or so transformed into dark ovals (Dyudina et al., 2007). The ovals were found to be dark over a wide spectral range, which led Baines et al. (2009) to suggest the possibility that a broadband absorber such as soot produced by lightning could play a significant role in darkening the <span class="hlt">clouds</span> relative to their surroundings. Here we show that an alternative explanation, which is that the <span class="hlt">clouds</span> are less reflective because of reduced optical depth, provides an excellent fit to near infrared spectra of similar features obtained by the Cassini Visual and Infrared Mapping Spectrometer (VIMS) in 2008, and leads to a plausible scenario for <span class="hlt">cloud</span> evolution. We find that the background <span class="hlt">clouds</span> and the oval <span class="hlt">clouds</span> are both dominated by the optical properties of a ubiquitous upper <span class="hlt">cloud</span> <span class="hlt">layer</span>, which has the same particle size in both regions, but about half the optical depth and physical thickness in the dark oval regions. The dark oval regions are also marked by enhanced emissions in the 5-μm window region, a result of lower optical depth of the deep <span class="hlt">cloud</span> <span class="hlt">layer</span> near 3.1-3.8 bar, presumably composed of ammonium hydrosulfide (NH4SH). The bright storm <span class="hlt">clouds</span> completely block this deep thermal emission with a thick <span class="hlt">layer</span> of ammonia (NH3) <span class="hlt">clouds</span> extending from the <span class="hlt">middle</span> of the main visible <span class="hlt">cloud</span> <span class="hlt">layer</span> probably as deep as the 1.7-bar NH3 condensation level. Other condensates might also be present at higher pressures, but are obscured by the NH3 <span class="hlt">cloud</span>. The strong 3-μm spectral absorption that was displayed by Saturn's Great Storm of 2010-2011 (Sromovsky et al., 2013) is weaker in these storms because the contrast is</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUFM.P53A..11H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUFM.P53A..11H"><span>Snow <span class="hlt">Clouds</span> and the Carbon Dioxide Cycle on Mars</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hayne, P. O.; Paige, D. A.</p> <p>2009-12-01</p> <p>The present climate of Mars is strongly influenced by the energy balance at the planet’s poles, with ~30% of the atmospheric mass exchanged seasonally with the polar ice caps. While the spring and summer sublimation process is observable in sunlight, the deposition process occurs in the darkness of polar night. We present direct radiometric observations of carbon dioxide snow <span class="hlt">clouds</span> from the Mars Climate Sounder (MCS) and estimate the rate of deposition due to snowfall. We also present radiative transfer models capable of reproducing the observations and providing constraints on the radiative and thermal properties of the cap-atmosphere system. Snow <span class="hlt">clouds</span> display a multi-<span class="hlt">layered</span> structure with greatest opacity near the surface and extending to typical altitudes of about 20 km, with equivalent normal visible optical depths of ~0.1. Our modeling suggests the observed carbon dioxide snow grains are ~10 μm in radius, implying modest deposition rates, and suggesting the majority of the seasonal cap is deposited in a vertical region within one MCS field of view (or ~1 km) of the surface. Models reproducing the MCS limb observations only reproduce the nadir observations if the surface (or near-surface) is an optically thick <span class="hlt">layer</span> of small (< 100 μm radius) carbon dioxide grains, which are therefore the primary cause of radiometrically cold areas (“cold spots”) observed since the Viking era. For the extreme polar regions, a persistent, ~500 km diameter snow <span class="hlt">cloud</span> is strongly coupled to the most active cold spots, and smaller <span class="hlt">clouds</span> (< 50 km diameter) in the latitude range 60-80°, though unobserved, cannot be ruled out by the MCS data. Based on this correlation, and observations of cold spots recurring near topographic slopes, we conclude that deposition is indeed linked to <span class="hlt">cloud</span> formation, with the majority of material condensing below ~1 km altitude. Optically thin water ice <span class="hlt">layers</span> are necessary to accurately model the MCS spectrum, particularly at altitudes</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19990102921','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19990102921"><span>Effects of Precipitation on Ocean Mixed-<span class="hlt">Layer</span> Temperature and Salinity as Simulated in a 2-D Coupled Ocean-<span class="hlt">Cloud</span> Resolving Atmosphere Model</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Li, Xiaofan; Sui, C.-H.; Lau, K-M.; Adamec, D.</p> <p>1999-01-01</p> <p>A two-dimensional coupled ocean-<span class="hlt">cloud</span> resolving atmosphere model is used to investigate possible roles of convective scale ocean disturbances induced by atmospheric precipitation on ocean mixed-<span class="hlt">layer</span> heat and salt budgets. The model couples a <span class="hlt">cloud</span> resolving model with an embedded mixed <span class="hlt">layer</span>-ocean circulation model. Five experiment are performed under imposed large-scale atmospheric forcing in terms of vertical velocity derived from the TOGA COARE observations during a selected seven-day period. The dominant variability of mixed-<span class="hlt">layer</span> temperature and salinity are simulated by the coupled model with imposed large-scale forcing. The mixed-<span class="hlt">layer</span> temperatures in the coupled experiments with 1-D and 2-D ocean models show similar variations when salinity effects are not included. When salinity effects are included, however, differences in the domain-mean mixed-<span class="hlt">layer</span> salinity and temperature between coupled experiments with 1-D and 2-D ocean models could be as large as 0.3 PSU and 0.4 C respectively. Without fresh water effects, the nocturnal heat loss over ocean surface causes deep mixed <span class="hlt">layers</span> and weak cooling rates so that the nocturnal mixed-<span class="hlt">layer</span> temperatures tend to be horizontally-uniform. The fresh water flux, however, causes shallow mixed <span class="hlt">layers</span> over convective areas while the nocturnal heat loss causes deep mixed <span class="hlt">layer</span> over convection-free areas so that the mixed-<span class="hlt">layer</span> temperatures have large horizontal fluctuations. Furthermore, fresh water flux exhibits larger spatial fluctuations than surface heat flux because heavy rainfall occurs over convective areas embedded in broad non-convective or clear areas, whereas diurnal signals over whole model areas yield high spatial correlation of surface heat flux. As a result, mixed-<span class="hlt">layer</span> salinities contribute more to the density differences than do mixed-<span class="hlt">layer</span> temperatures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.A12A..07M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.A12A..07M"><span>An imager-based multispectral retrieval of above-<span class="hlt">cloud</span> absorbing aerosol optical depth and the optical and microphysical properties of underlying marine stratocumulus <span class="hlt">clouds</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Meyer, K.; Platnick, S. E.; Zhang, Z.</p> <p>2014-12-01</p> <p><span class="hlt">Clouds</span>, 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 <span class="hlt">layer</span> (MBL) <span class="hlt">clouds</span> over the southeastern Atlantic Ocean, which underlie a near-persistent smoke <span class="hlt">layer</span> produced from extensive biomass burning throughout the southern African savanna during austral winter. The absorption of the above-<span class="hlt">cloud</span> smoke <span class="hlt">layer</span>, which increases with decreasing wavelength, can introduce biases into imager-based <span class="hlt">cloud</span> optical and microphysical property retrievals of the underlying MBL <span class="hlt">clouds</span>. This effect is more pronounced for <span class="hlt">cloud</span> optical thickness retrievals, which are typically derived from the visible or near-IR wavelength channels (effective particle size retrievals are derived from short and mid-wave IR channels that are less affected by aerosol absorption). Here, a new method is introduced to simultaneously retrieve the above-<span class="hlt">cloud</span> smoke aerosol optical depth (AOD) and the unbiased <span class="hlt">cloud</span> optical thickness (COT) and effective radius (CER) using multiple spectral channels in the visible and near- and shortwave-IR. The technique has been applied to MODIS, and retrieval results and statistics, as well as comparisons with other A-Train sensors, are shown.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20050217157','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20050217157"><span>Detection and Retrieval of Multi-<span class="hlt">Layered</span> <span class="hlt">Cloud</span> Properties Using Satellite Data</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Minnis, Patrick; Sun-Mack, Sunny; Chen, Yan; Yi, Helen; Huang, Jian-Ping; Nguyen, Louis; Khaiyer, Mandana M.</p> <p>2005-01-01</p> <p>Four techniques for detecting multilayered <span class="hlt">clouds</span> and retrieving the <span class="hlt">cloud</span> properties using satellite data are explored to help address the need for better quantification of <span class="hlt">cloud</span> 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 <span class="hlt">clouds</span>, 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. <span class="hlt">Cloud</span> properties derived from MODIS data for the <span class="hlt">Clouds</span> and the Earth's Radiant Energy System (CERES) Project are used to classify <span class="hlt">cloud</span> 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 <span class="hlt">clouds</span>. 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 <span class="hlt">cloud</span> scenes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005SPIE.5979...70M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005SPIE.5979...70M"><span>Detection and retrieval of multi-<span class="hlt">layered</span> <span class="hlt">cloud</span> properties using satellite data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Minnis, Patrick; Sun-Mack, Sunny; Chen, Yan; Yi, Helen; Huang, Jianping; Nguyen, Louis; Khaiyer, Mandana M.</p> <p>2005-10-01</p> <p>Four techniques for detecting multilayered <span class="hlt">clouds</span> and retrieving the <span class="hlt">cloud</span> properties using satellite data are explored to help address the need for better quantification of <span class="hlt">cloud</span> 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 <span class="hlt">clouds</span>, 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. <span class="hlt">Cloud</span> properties derived from MODIS data for the <span class="hlt">Clouds</span> and the Earth's Radiant Energy System (CERES) Project are used to classify <span class="hlt">cloud</span> 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 <span class="hlt">clouds</span>. 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 <span class="hlt">cloud</span> scenes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20030071257&hterms=cloud+database&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dcloud%2Bdatabase','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20030071257&hterms=cloud+database&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dcloud%2Bdatabase"><span>Satellite and Surface Data Synergy for Developing a 3D <span class="hlt">Cloud</span> Structure and Properties Characterization Over the ARM SGP. Stage 1: <span class="hlt">Cloud</span> Amounts, Optical Depths, and <span class="hlt">Cloud</span> Heights Reconciliation</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Genkova, I.; Long, C. N.; Heck, P. W.; Minnis, P.</p> <p>2003-01-01</p> <p>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 <span class="hlt">cloud</span> structure and properties over the ARM Southern Great Plains (SGP). We take the approach of juxtaposing the <span class="hlt">cloud</span> properties as retrieved from independent satellite and ground-based retrievals, and looking at the statistics of the <span class="hlt">cloud</span> 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 <span class="hlt">cloud</span> 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, <span class="hlt">cloud</span> height, multi-<span class="hlt">layer</span> <span class="hlt">cloud</span> presence, and solar zenith angle (SZA). For the SGP Central Facility, where output from the active remote sensing <span class="hlt">cloud</span> <span class="hlt">layer</span> (ARSCL) valueadded product (VAP) is available, we study the uncertainty of satellite estimated <span class="hlt">cloud</span> heights and evaluate the impact of this uncertainty for radiative studies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA00582&hterms=level&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DA%2Blevel','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA00582&hterms=level&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DA%2Blevel"><span>Jupiter's Multi-level <span class="hlt">Clouds</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1997-01-01</p> <p><span class="hlt">Clouds</span> and hazes at various altitudes within the dynamic Jovian atmosphere are revealed by multi-color imaging taken by the Near-Infrared Mapping Spectrometer (NIMS) onboard the Galileo spacecraft. These images were taken during the second orbit (G2) on September 5, 1996 from an early-morning vantage point 2.1 million kilometers (1.3 million miles) above Jupiter. They show the planet's appearance as viewed at various near-infrared wavelengths, with distinct differences due primarily to variations in the altitudes and opacities of the <span class="hlt">cloud</span> systems. The top left and right images, taken at 1.61 microns and 2.73 microns respectively, show relatively clear views of the deep atmosphere, with <span class="hlt">clouds</span> down to a level about three times the atmospheric pressure at the Earth's surface.<p/>By contrast, the <span class="hlt">middle</span> image in top row, taken at 2.17 microns, shows only the highest altitude <span class="hlt">clouds</span> and hazes. This wavelength is severely affected by the absorption of light by hydrogen gas, the main constituent of Jupiter's atmosphere. Therefore, only the Great Red Spot, the highest equatorial <span class="hlt">clouds</span>, a small feature at mid-northern latitudes, and thin, high photochemical polar hazes can be seen. In the lower left image, at 3.01 microns, deeper <span class="hlt">clouds</span> can be seen dimly against gaseous ammonia and methane absorption. In the lower <span class="hlt">middle</span> image, at 4.99 microns, the light observed is the planet's own indigenous heat from the deep, warm atmosphere.<p/>The false color image (lower right) succinctly shows various <span class="hlt">cloud</span> and haze levels seen in the Jovian atmosphere. This image indicates the temperature and altitude at which the light being observed is produced. Thermally-rich red areas denote high temperatures from photons in the deep atmosphere leaking through minimal <span class="hlt">cloud</span> cover; green denotes cool temperatures of the tropospheric <span class="hlt">clouds</span>; blue denotes cold of the upper troposphere and lower stratosphere. The polar regions appear purplish, because small-particle hazes allow leakage and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006AGUFM.A54B..06M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AGUFM.A54B..06M"><span>Evaluation of Passive Multilayer <span class="hlt">Cloud</span> Detection Using Preliminary <span class="hlt">Cloud</span>Sat and CALIPSO <span class="hlt">Cloud</span> Profiles</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Minnis, P.; Sun-Mack, S.; Chang, F.; Huang, J.; Nguyen, L.; Ayers, J. K.; Spangenberg, D. A.; Yi, Y.; Trepte, C. R.</p> <p>2006-12-01</p> <p>During the last few years, several algorithms have been developed to detect and retrieve multilayered <span class="hlt">clouds</span> using passive satellite data. Assessing these techniques has been difficult due to the need for active sensors such as <span class="hlt">cloud</span> radars and lidars that can "see" through different <span class="hlt">layers</span> of <span class="hlt">clouds</span>. Such sensors have been available only at a few surface sites and on aircraft during field programs. With the launch of the CALIPSO and <span class="hlt">Cloud</span>Sat satellites on April 28, 2006, it is now possible to observe multilayered systems all over the globe using collocated <span class="hlt">cloud</span> radar and lidar data. As part of the A- Train, these new active sensors are also matched in time ad space with passive measurements from the Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) and Advanced Microwave Scanning Radiometer - EOS (AMSR-E). The <span class="hlt">Clouds</span> and the Earth's Radiant Energy System (CERES) has been developing and testing algorithms to detect ice-over-water overlapping <span class="hlt">cloud</span> systems and to retrieve the <span class="hlt">cloud</span> liquid path (LWP) and ice water path (IWP) for those systems. One technique uses a combination of the CERES <span class="hlt">cloud</span> retrieval algorithm applied to MODIS data and a microwave retrieval method applied to AMSR-E data. The combination of a CO2-slicing <span class="hlt">cloud</span> retireval technique with the CERES algorithms applied to MODIS data (Chang et al., 2005) is used to detect and analyze such overlapped systems that contain thin ice <span class="hlt">clouds</span>. A third technique uses brightness temperature differences and the CERES algorithms to detect similar overlapped methods. This paper uses preliminary <span class="hlt">Cloud</span>Sat and CALIPSO data to begin a global scale assessment of these different methods. The long-term goals are to assess and refine the algorithms to aid the development of an optimal combination of the techniques to better monitor ice 9and liquid water <span class="hlt">clouds</span> in overlapped conditions.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_14 --> <div id="page_15" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="281"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005AGUSM.A54B..06M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005AGUSM.A54B..06M"><span>Evaluation of Passive Multilayer <span class="hlt">Cloud</span> Detection Using Preliminary <span class="hlt">Cloud</span>Sat and CALIPSO <span class="hlt">Cloud</span> Profiles</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Minnis, P.; Sun-Mack, S.; Chang, F.; Huang, J.; Nguyen, L.; Ayers, J. K.; Spangenberg, D. A.; Yi, Y.; Trepte, C. R.</p> <p>2005-05-01</p> <p>During the last few years, several algorithms have been developed to detect and retrieve multilayered <span class="hlt">clouds</span> using passive satellite data. Assessing these techniques has been difficult due to the need for active sensors such as <span class="hlt">cloud</span> radars and lidars that can "see" through different <span class="hlt">layers</span> of <span class="hlt">clouds</span>. Such sensors have been available only at a few surface sites and on aircraft during field programs. With the launch of the CALIPSO and <span class="hlt">Cloud</span>Sat satellites on April 28, 2006, it is now possible to observe multilayered systems all over the globe using collocated <span class="hlt">cloud</span> radar and lidar data. As part of the A- Train, these new active sensors are also matched in time ad space with passive measurements from the Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) and Advanced Microwave Scanning Radiometer - EOS (AMSR-E). The <span class="hlt">Clouds</span> and the Earth's Radiant Energy System (CERES) has been developing and testing algorithms to detect ice-over-water overlapping <span class="hlt">cloud</span> systems and to retrieve the <span class="hlt">cloud</span> liquid path (LWP) and ice water path (IWP) for those systems. One technique uses a combination of the CERES <span class="hlt">cloud</span> retrieval algorithm applied to MODIS data and a microwave retrieval method applied to AMSR-E data. The combination of a CO2-slicing <span class="hlt">cloud</span> retireval technique with the CERES algorithms applied to MODIS data (Chang et al., 2005) is used to detect and analyze such overlapped systems that contain thin ice <span class="hlt">clouds</span>. A third technique uses brightness temperature differences and the CERES algorithms to detect similar overlapped methods. This paper uses preliminary <span class="hlt">Cloud</span>Sat and CALIPSO data to begin a global scale assessment of these different methods. The long-term goals are to assess and refine the algorithms to aid the development of an optimal combination of the techniques to better monitor ice 9and liquid water <span class="hlt">clouds</span> in overlapped conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19920031384&hterms=marine+pollution&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dmarine%2Bpollution','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19920031384&hterms=marine+pollution&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dmarine%2Bpollution"><span>Optical properties of marine stratocumulus <span class="hlt">clouds</span> modified by ship track effluents</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>King, Michael D.; Nakajima, Teruyuki; Radke, Lawrence F.</p> <p>1990-01-01</p> <p>Results are presented from multispectral radiation measurements made within a marine stratocumulus <span class="hlt">cloud</span> <span class="hlt">layer</span> modified by ship-track effluents. The measurements showed that, compared with nearby noncontaminated <span class="hlt">clouds</span> not affected by pollution, the upwelling intensity field of the modified stratocumulus <span class="hlt">clouds</span> 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 <span class="hlt">cloud</span> droplets, and a reduced absorption in the contaminated <span class="hlt">cloud</span> <span class="hlt">layer</span> compared to a noncontaminated <span class="hlt">cloud</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018SPIE10697E..1IL','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018SPIE10697E..1IL"><span>Research on <span class="hlt">cloud</span> background infrared radiation simulation based on fractal and statistical data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Liu, Xingrun; Xu, Qingshan; Li, Xia; Wu, Kaifeng; Dong, Yanbing</p> <p>2018-02-01</p> <p><span class="hlt">Cloud</span> is an important natural phenomenon, and its radiation causes serious interference to infrared detector. Based on fractal and statistical data, a method is proposed to realize <span class="hlt">cloud</span> background simulation, and <span class="hlt">cloud</span> infrared radiation data field is assigned using satellite radiation data of <span class="hlt">cloud</span>. A <span class="hlt">cloud</span> infrared radiation simulation model is established using matlab, and it can generate <span class="hlt">cloud</span> background infrared images for different <span class="hlt">cloud</span> types (low <span class="hlt">cloud</span>, <span class="hlt">middle</span> <span class="hlt">cloud</span>, and high <span class="hlt">cloud</span>) in different months, bands and sensor zenith angles.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.V21D..06J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.V21D..06J"><span>Why Did the 2010 Eyjafjallajokull Volcanic Eruption <span class="hlt">Cloud</span> Last So Long?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jellinek, M.; Carazzo, G.</p> <p>2013-12-01</p> <p>The global economic consequences of the relatively small Eyjafjallajokull eruption in the spring of 2010 caught the world off guard. That the eruption <span class="hlt">cloud</span> lasted for several months rather than weeks, efficiently disrupting air travel and the holiday plans of thousands of tourists, drew arguably more attention and a certainly garnered a highly emotional response. The longevity of this eruption <span class="hlt">cloud</span> was touted to be "an anomaly". However, this anomaly nearly repeated itself the following year in the form of the 2011 Puyehue-Cordon Caulle eruption <span class="hlt">cloud</span>. A major reason that the behavior of the 2010 Eyjafjallajokul <span class="hlt">cloud</span> was surprising is that "standard" models for ash sedimentation (i.e., heavy particles fall out of the <span class="hlt">cloud</span> faster than light particles) are incomplete. Observations of the 2010 Eyjafjallajokull, as well as the structure of atmospheric aerosol <span class="hlt">clouds</span> from the 1991 Mt Pinatubo event, suggest that an additional key process in addition to particle settling is the production of internal <span class="hlt">layering</span>. We use analog experiments on turbulent particle-laden umbrella <span class="hlt">clouds</span> and simple models to show that this <span class="hlt">layering</span> occurs where natural convection driven by particle sedimentation and the differential diffusion of primarily heat and fine particles give rise to a large scale instability leading to this <span class="hlt">layering</span>. This 'particle diffusive convection' strongly influences <span class="hlt">cloud</span> longevity where volcanic umbrella <span class="hlt">clouds</span> are enriched in fine ash. More generally, volcanic <span class="hlt">cloud</span> residence times will depend on ash fluxes related to both individual particle settling and diffusive convection. We discuss a new sedimentation model that includes both contributions to the particle flux and explains the the rate of change of particle concentration in the 1982 El Chichon, 1991 Mt Pinatubo and 1992 Mt Spurr ash-<span class="hlt">clouds</span>. Examples of periodic <span class="hlt">layering</span> in volcanic <span class="hlt">clouds</span> compared with experiments in which periodic <span class="hlt">layering</span> emerges as a result of buoyancy effects related to a particle</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003AGUFM.A22A1054N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003AGUFM.A22A1054N"><span>Retrieval of <span class="hlt">Cloud</span> Properties for Partially <span class="hlt">Cloud</span>-Filled Pixels During CRYSTAL-FACE</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nguyen, L.; Minnis, P.; Smith, W. L.; Khaiyer, M. M.; Heck, P. W.; Sun-Mack, S.; Uttal, T.; Comstock, J.</p> <p>2003-12-01</p> <p>Partially <span class="hlt">cloud</span>-filled pixels can be a significant problem for remote sensing of <span class="hlt">cloud</span> properties. Generally, the optical depth and effective particle sizes are often too small or too large, respectively, when derived from radiances that are assumed to be overcast but contain radiation from both clear and <span class="hlt">cloud</span> areas within the satellite imager field of view. This study presents a method for reducing the impact of such partially <span class="hlt">cloud</span> field pixels by estimating the <span class="hlt">cloud</span> fraction within each pixel using higher resolution visible (VIS, 0.65mm) imager data. Although the nominal resolution for most channels on the Geostationary Operational Environmental Satellite (GOES) imager and the Moderate Resolution Imaging Spectroradiometer (MODIS) on Terra are 4 and 1 km, respectively, both instruments also take VIS channel data at 1 km and 0.25 km, respectively. Thus, it may be possible to obtain an improved estimate of <span class="hlt">cloud</span> fraction within the lower resolution pixels by using the information contained in the higher resolution VIS data. GOES and MODIS multi-spectral data, taken during the Cirrus Regional Study of Tropical Anvils and Cirrus <span class="hlt">Layers</span> - Florida Area Cirrus Experiment (CRYSTAL-FACE), are analyzed with the algorithm used for the Atmospheric Radiation Measurement Program (ARM) and the <span class="hlt">Clouds</span> and Earth's Radiant Energy System (CERES) to derive <span class="hlt">cloud</span> amount, temperature, height, phase, effective particle size, optical depth, and water path. Normally, the algorithm assumes that each pixel is either entirely clear or cloudy. In this study, a threshold method is applied to the higher resolution VIS data to estimate the partial <span class="hlt">cloud</span> fraction within each low-resolution pixel. The <span class="hlt">cloud</span> properties are then derived from the observed low-resolution radiances using the <span class="hlt">cloud</span> cover estimate to properly extract the radiances due only to the cloudy part of the scene. This approach is applied to both GOES and MODIS data to estimate the improvement in the retrievals for each</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006AGUFM.A51E0135S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AGUFM.A51E0135S"><span>An Integrated <span class="hlt">Cloud</span>-Aerosol-Radiation Product Using CERES, MODIS, CALIPSO and <span class="hlt">Cloud</span>Sat Data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sun-Mack, S.; Gibson, S.; Chen, Y.; Wielicki, B.; Minnis, P.</p> <p>2006-12-01</p> <p>The goal of this paper is to provide the first integrated data set of global vertical profiles of aerosols, <span class="hlt">clouds</span>, and radiation using the combined NASA A-Train data from Aqua CERES and MODIS, CALIPSO, and <span class="hlt">Cloud</span>Sat. All of these instruments are flying in formation as part of the Aqua Train, or A-Train. This paper will present the preliminary results of merging aerosol and <span class="hlt">cloud</span> data from the CALIPSO active lidar, <span class="hlt">cloud</span> data from <span class="hlt">Cloud</span>Sat, integrated column aerosol and <span class="hlt">cloud</span> data from the MODIS CERES analyses, and surface and top-of-atmosphere broadband radiation fluxes from CERES. These new data will provide unprecedented ability to test and improve global <span class="hlt">cloud</span> and aerosol models, to investigate aerosol direct and indirect radiative forcing, and to validate the accuracy of global aerosol, <span class="hlt">cloud</span>, and radiation data sets especially in polar regions and for multi-<span class="hlt">layered</span> <span class="hlt">cloud</span> conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20040139773','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20040139773"><span>Development of a Global Multilayered <span class="hlt">Cloud</span> Retrieval System</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Huang, J.; Minnis, P.; Lin, B.; Yi, Y.; Ayers, J. K.; Khaiyer, M. M.; Arduini, R.; Fan, T.-F</p> <p>2004-01-01</p> <p>A more rigorous multilayered <span class="hlt">cloud</span> retrieval system has been developed to improve the determination of high <span class="hlt">cloud</span> properties in multilayered <span class="hlt">clouds</span>. The MCRS attempts a more realistic interpretation of the radiance field than earlier methods because it explicitly resolves the radiative transfer that would produce the observed radiances. A two-<span class="hlt">layer</span> <span class="hlt">cloud</span> model was used to simulate multilayered <span class="hlt">cloud</span> radiative characteristics. Despite the use of a simplified two-<span class="hlt">layer</span> <span class="hlt">cloud</span> reflectance parameterization, the MCRS clearly produced a more accurate retrieval of ice water path than simple differencing techniques used in the past. More satellite data and ground observation have to be used to test the MCRS. The MCRS methods are quite appropriate for interpreting the radiances when the high <span class="hlt">cloud</span> has a relatively large optical depth (tau(sub I) greater than 2). For thinner ice <span class="hlt">clouds</span>, a more accurate retrieval might be possible using infrared methods. Selection of an ice <span class="hlt">cloud</span> retrieval and a variety of other issues must be explored before a complete global application of this technique can be implemented. Nevertheless, the initial results look promising.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940019904','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940019904"><span>GEWEX <span class="hlt">Cloud</span> Systems Study (GCSS)</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Moncrieff, Mitch</p> <p>1993-01-01</p> <p>The Global Energy and Water Cycle Experiment (GEWEX) <span class="hlt">Cloud</span> Systems Study (GCSS) program seeks to improve the physical understanding of sub-grid scale <span class="hlt">cloud</span> processes and their representation in parameterization schemes. By improving the description and understanding of key <span class="hlt">cloud</span> system processes, GCSS aims to develop the necessary parameterizations in climate and numerical weather prediction (NWP) models. GCSS will address these issues mainly through the development and use of <span class="hlt">cloud</span>-resolving or cumulus ensemble models to generate realizations of a set of archetypal <span class="hlt">cloud</span> systems. The focus of GCSS is on mesoscale <span class="hlt">cloud</span> systems, including precipitating convectively-driven <span class="hlt">cloud</span> systems like MCS's and boundary <span class="hlt">layer</span> <span class="hlt">clouds</span>, rather than individual <span class="hlt">clouds</span>, and on their large-scale effects. Some of the key scientific issues confronting GCSS that particularly relate to research activities in the central U.S. are presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19930044345&hterms=marine+pollution&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dmarine%2Bpollution','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930044345&hterms=marine+pollution&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dmarine%2Bpollution"><span>Optical properties of marine stratocumulus <span class="hlt">clouds</span> modified by ships</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>King, Michael D.; Radke, Lawrence F.; Hobbs, Peter V.</p> <p>1993-01-01</p> <p>Results are presented of an application of the diffusion domain method to multispectral solar radiation measurements obtained deep within a marine stratocumulus <span class="hlt">cloud</span> <span class="hlt">layer</span> 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 <span class="hlt">cloud</span> <span class="hlt">layer</span>. 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 <span class="hlt">cloud</span> absorption radiometer mounted on the University of Washington's C-131A research aircraft. It is shown that the total optical thickness of the <span class="hlt">cloud</span> <span class="hlt">layer</span> 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 <span class="hlt">cloud</span> droplet size that occurred within the ship tracks.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA00221&hterms=How+get+human+cloud&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DHow%2Bget%2Bhuman%2Bcloud%253F','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA00221&hterms=How+get+human+cloud&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DHow%2Bget%2Bhuman%2Bcloud%253F"><span>Venus - Lower-level <span class="hlt">Clouds</span> As Seen By NIMS</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1990-01-01</p> <p>These images are two versions of a near-infrared map of lower-level <span class="hlt">clouds</span> on the night side of Venus, obtained by the Near Infrared Mapping Spectrometer aboard the Galileo spacecraft as it approached the planet February 10, 1990. Taken from an altitude of about 60,000 miles above the planet, at an infrared wavelength of 2.3 microns (about three times the longest wavelength visible to the human eye) the map shows the turbulent, cloudy <span class="hlt">middle</span> atmosphere some 30-33 miles above the surface, 6-10 miles below the visible cloudtops. The image to the left shows the radiant heat from the lower atmosphere (about 400 degrees Fahrenheit) shining through the sulfuric acid <span class="hlt">clouds</span>, which appear as much as 10 times darker than the bright gaps between <span class="hlt">clouds</span>. This <span class="hlt">cloud</span> <span class="hlt">layer</span> is at about -30 degrees Fahrenheit, at a pressure about 1/2 Earth's atmospheric pressure. About 2/3 of the dark hemisphere is visible, centered on longitude 350 West, with bright slivers of daylit high <span class="hlt">clouds</span> visible at top and bottom left. The right image, a modified negative, represents what scientists believe would be the visual appearance of this mid-level <span class="hlt">cloud</span> deck in daylight, with the <span class="hlt">clouds</span> reflecting sunlight instead of blocking out infrared from the hot planet and lower atmosphere. Near the equator, the <span class="hlt">clouds</span> appear fluffy and blocky; farther north, they are stretched out into East-West filaments by winds estimated at more than 150 mph, while the poles are capped by thick <span class="hlt">clouds</span> at this altitude. The Near Infrared Mapping Spectrometer (NIMS) on the Galileo spacecraft is a combined mapping (imaging) and spectral instrument. It can sense 408 contiguous wavelengths from 0.7 microns (deep red) to 5.2 microns, and can construct a map or image by mechanical scanning. It can spectroscopically analyze atmospheres and surfaces and construct thermal and chemical maps. Designed and operated by scientists and engineers at the Jet Propulsion Laboratory, NIMS involves 15 scientists in the U.S., England, and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018PASJ...70S..46F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018PASJ...70S..46F"><span>Molecular <span class="hlt">clouds</span> toward three Spitzer bubbles S116, S117, and S118: Evidence for a <span class="hlt">cloud-cloud</span> collision which formed the three H II regions and a 10 pc scale molecular cavity</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fukui, Yasuo; Ohama, Akio; Kohno, Mikito; Torii, Kazufumi; Fujita, Shinji; Hattori, Yusuke; Nishimura, Atsushi; Yamamoto, Hiroaki; Tachihara, Kengo</p> <p>2018-05-01</p> <p>We carried out a molecular-line study toward the three Spitzer bubbles S116, S117, and S118, which show active formation of high-mass stars. We found molecular gas consisting of two components with a velocity difference of ˜5 km s-1. One of them, the small <span class="hlt">cloud</span>, has a typical velocity of -63 km s-1 and the other, the large <span class="hlt">cloud</span>, has one of -58 km s-1. The large <span class="hlt">cloud</span> has a nearly circular intensity depression, the size of which is similar to that of the small <span class="hlt">cloud</span>. We present an interpretation that its cavity was created by a collision between the two <span class="hlt">clouds</span> and that this collision compressed the gas into a dense <span class="hlt">layer</span> elongating along the western rim of the small <span class="hlt">cloud</span>. In this scenario, the O stars including those in the three Spitzer bubbles were formed in the interface <span class="hlt">layer</span> compressed by the collision. Assuming that the relative motion of the <span class="hlt">clouds</span> has a tilt of 45° to the line of sight, we estimate that the collision continued for the last 1 Myr at a relative velocity of ˜10 km s-1. In the S116-S117-S118 system the H II regions are located outside of the cavity. This morphology is ascribed to the density-bound distribution of the large <span class="hlt">cloud</span> which caused the H II regions to expand more easily toward the outer part of the large <span class="hlt">cloud</span> than towards the inside of the cavity. The present case proves that a <span class="hlt">cloud-cloud</span> collision creates a cavity without the action of O-star feedback, and suggests that the collision-compressed <span class="hlt">layer</span> is highly filamentary.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140016620','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140016620"><span>Piezoelectric Resonator with Two <span class="hlt">Layers</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Stephanou, Philip J. (Inventor); Black, Justin P. (Inventor)</p> <p>2013-01-01</p> <p>A piezoelectric resonator device includes: a top electrode <span class="hlt">layer</span> with a patterned structure, a top piezoelectric <span class="hlt">layer</span> adjacent to the top <span class="hlt">layer</span>, a <span class="hlt">middle</span> metal <span class="hlt">layer</span> adjacent to the top piezoelectric <span class="hlt">layer</span> opposite the top <span class="hlt">layer</span>, a bottom piezoelectric <span class="hlt">layer</span> adjacent to the <span class="hlt">middle</span> <span class="hlt">layer</span> opposite the top piezoelectric <span class="hlt">layer</span>, and a bottom electrode <span class="hlt">layer</span> with a patterned structure and adjacent to the bottom piezoelectric <span class="hlt">layer</span> opposite the <span class="hlt">middle</span> <span class="hlt">layer</span>. The top <span class="hlt">layer</span> includes a first plurality of electrodes inter-digitated with a second plurality of electrodes. A first one of the electrodes in the top <span class="hlt">layer</span> and a first one of the electrodes in the bottom <span class="hlt">layer</span> are coupled to a first contact, and a second one of the electrodes in the top <span class="hlt">layer</span> and a second one of the electrodes in the bottom <span class="hlt">layer</span> are coupled to a second contact.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.A43B0199P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.A43B0199P"><span>Ultra-Parameterized CAM: Progress Towards Low-<span class="hlt">Cloud</span> Permitting Superparameterization</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Parishani, H.; Pritchard, M. S.; Bretherton, C. S.; Khairoutdinov, M.; Wyant, M. C.; Singh, B.</p> <p>2016-12-01</p> <p>A leading source of uncertainty in climate feedback arises from the representation of low <span class="hlt">clouds</span>, which are not resolved but depend on small-scale physical processes (e.g. entrainment, boundary <span class="hlt">layer</span> turbulence) that are heavily parameterized. We show results from recent attempts to achieve an explicit representation of low <span class="hlt">clouds</span> by pushing the computational limits of <span class="hlt">cloud</span> superparameterization to resolve boundary-<span class="hlt">layer</span> eddy scales relevant to marine stratocumulus (250m horizontal and 20m vertical length scales). This extreme configuration is called "ultraparameterization". Effects of varying horizontal vs. vertical resolution are analyzed in the context of altered constraints on the turbulent kinetic energy statistics of the marine boundary <span class="hlt">layer</span>. We show that 250m embedded horizontal resolution leads to a more realistic boundary <span class="hlt">layer</span> vertical structure, but also to an unrealistic <span class="hlt">cloud</span> pulsation that cannibalizes time mean LWP. We explore the hypothesis that feedbacks involving horizontal advection (not typically encountered in offline LES that neglect this degree of freedom) may conspire to produce such effects and present strategies to compensate. The results are relevant to understanding the emergent behavior of quasi-resolved low <span class="hlt">cloud</span> decks in a multi-scale modeling framework within a previously unencountered grey zone of better resolved boundary-<span class="hlt">layer</span> turbulence.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://eosweb.larc.nasa.gov/project/misr/gallery/complex_clouds','SCIGOV-ASDC'); return false;" href="https://eosweb.larc.nasa.gov/project/misr/gallery/complex_clouds"><span>Complex <span class="hlt">Clouds</span></span></a></p> <p><a target="_blank" href="http://eosweb.larc.nasa.gov/">Atmospheric Science Data Center </a></p> <p></p> <p>2013-04-16</p> <p>... article title:  Multi-<span class="hlt">layer</span> <span class="hlt">Clouds</span> Over the South Indian Ocean     View Larger Image ... System-2 path 155. MISR was built and is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Science Mission ...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010ACP....1012261S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010ACP....1012261S"><span>Simulation of low <span class="hlt">clouds</span> in the Southeast Pacific by the NCEP GFS: sensitivity to vertical mixing</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sun, R.; Moorthi, S.; Xiao, H.; Mechoso, C. R.</p> <p>2010-12-01</p> <p>The NCEP Global Forecast System (GFS) model has an important systematic error shared by many other models: stratocumuli are missed over the subtropical eastern oceans. It is shown that this error can be alleviated in the GFS by introducing a consideration of the low-level inversion and making two modifications in the model's representation of vertical mixing. The modifications consist of (a) the elimination of background vertical diffusion above the inversion and (b) the incorporation of a stability parameter based on the <span class="hlt">cloud</span>-top entrainment instability (CTEI) criterion, which limits the strength of shallow convective mixing across the inversion. A control simulation and three experiments are performed in order to examine both the individual and combined effects of modifications on the generation of the stratocumulus <span class="hlt">clouds</span>. Individually, both modifications result in enhanced cloudiness in the Southeast Pacific (SEP) region, although the cloudiness is still low compared to the ISCCP climatology. If the modifications are applied together, however, the total cloudiness produced in the southeast Pacific has realistic values. This nonlinearity arises as the effects of both modifications reinforce each other in reducing the leakage of moisture across the inversion. Increased moisture trapped below the inversion than in the control run without modifications leads to an increase in <span class="hlt">cloud</span> amount and <span class="hlt">cloud</span>-top radiative cooling. Then a positive feedback due to enhanced turbulent mixing in the planetary boundary <span class="hlt">layer</span> by <span class="hlt">cloud</span>-top radiative cooling leads to and maintains the stratocumulus cover. Although the amount of total cloudiness obtained with both modifications has realistic values, the relative contributions of low, <span class="hlt">middle</span>, and high <span class="hlt">layers</span> tend to differ from the observations. These results demonstrate that it is possible to simulate realistic marine boundary <span class="hlt">clouds</span> in large-scale models by implementing direct and physically based improvements in the model</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010ACPD...1018467S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010ACPD...1018467S"><span>Simulation of low <span class="hlt">clouds</span> in the Southeast Pacific by the NCEP GFS: sensitivity to vertical mixing</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sun, R.; Moorthi, S.; Xiao, H.; Mechoso, C.-R.</p> <p>2010-08-01</p> <p>The NCEP Global Forecast System (GFS) model has an important systematic error shared by many other models: stratocumuli are missed over the subtropical eastern oceans. It is shown that this error can be alleviated in the GFS by introducing a consideration of the low-level inversion and making two modifications in the model's representation of vertical mixing. The modifications consist of (a) the elimination of background vertical diffusion above the inversion and (b) the incorporation of a stability parameter based on the <span class="hlt">cloud</span>-top entrainment instability (CTEI) criterion, which limits the strength of shallow convective mixing across the inversion. A control simulation and three experiments are performed in order to examine both the individual and combined effects of modifications on the generation of the stratocumulus <span class="hlt">clouds</span>. Individually, both modifications result in enhanced cloudiness in the Southeast Pacific (SEP) region, although the cloudiness is still low compared to the ISCCP climatology. If the modifications are applied together, however, the total cloudiness produced in the southeast Pacific has realistic values. This nonlinearity arises as the effects of both modifications reinforce each other in reducing the leakage of moisture across the inversion. Increased moisture trapped below the inversion than in the control run without modifications leads to an increase in <span class="hlt">cloud</span> amount and <span class="hlt">cloud</span>-top radiative cooling. Then a positive feedback due to enhanced turbulent mixing in the planetary boundary <span class="hlt">layer</span> by <span class="hlt">cloud</span>-top radiative cooling leads to and maintains the stratocumulus cover. Although the amount of total cloudiness obtained with both modifications has realistic values, the relative contributions of low, <span class="hlt">middle</span>, and high <span class="hlt">layers</span> tend to differ from the observations. These results demonstrate that it is possible to simulate realistic marine boundary <span class="hlt">clouds</span> in large-scale models by implementing direct and physically based improvements in the model</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015ACP....15.8147S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015ACP....15.8147S"><span>Airborne observations and simulations of three-dimensional radiative interactions between Arctic boundary <span class="hlt">layer</span> <span class="hlt">clouds</span> and ice floes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schäfer, M.; Bierwirth, E.; Ehrlich, A.; Jäkel, E.; Wendisch, M.</p> <p>2015-07-01</p> <p>Based on airborne spectral imaging observations, three-dimensional (3-D) radiative effects between Arctic boundary <span class="hlt">layer</span> <span class="hlt">clouds</span> and highly variable Arctic surfaces were identified and quantified. A method is presented to discriminate between sea ice and open water under cloudy conditions based on airborne nadir reflectivity γλ measurements in the visible spectral range. In cloudy cases the transition of γλ from open water to sea ice is not instantaneous but horizontally smoothed. In general, <span class="hlt">clouds</span> reduce γλ above bright surfaces in the vicinity of open water, while γλ above open sea is enhanced. With the help of observations and 3-D radiative transfer simulations, this effect was quantified to range between 0 and 2200 m distance to the sea ice edge (for a dark-ocean albedo of αwater = 0.042 and a sea-ice albedo of αice = 0.91 at 645 nm wavelength). The affected distance Δ L was found to depend on both <span class="hlt">cloud</span> and sea ice properties. For a low-level <span class="hlt">cloud</span> at 0-200 m altitude, as observed during the Arctic field campaign VERtical Distribution of Ice in Arctic <span class="hlt">clouds</span> (VERDI) in 2012, an increase in the <span class="hlt">cloud</span> optical thickness τ from 1 to 10 leads to a decrease in Δ L from 600 to 250 m. An increase in the <span class="hlt">cloud</span> base altitude or <span class="hlt">cloud</span> geometrical thickness results in an increase in Δ L; for τ = 1/10 Δ L = 2200 m/1250 m in case of a <span class="hlt">cloud</span> at 500-1000 m altitude. To quantify the effect for different shapes and sizes of ice floes, radiative transfer simulations were performed with various albedo fields (infinitely long straight ice edge, circular ice floes, squares, realistic ice floe field). The simulations show that Δ L increases with increasing radius of the ice floe and reaches maximum values for ice floes with radii larger than 6 km (500-1000 m <span class="hlt">cloud</span> altitude), which matches the results found for an infinitely long, straight ice edge. Furthermore, the influence of these 3-D radiative effects on the retrieved <span class="hlt">cloud</span> optical properties was investigated</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA08198.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA08198.html"><span>Curious <span class="hlt">Clouds</span></span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2006-06-13</p> <p>Saturn atmosphere produces beautiful and sometimes perplexing features. Is the bright feature below center a rare crossing of a feature from a zone to a belt, or is it an illusion created by different <span class="hlt">cloud</span> <span class="hlt">layers</span> at different levels?</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1394932','SCIGOV-DOEDE'); return false;" href="https://www.osti.gov/servlets/purl/1394932"><span><span class="hlt">Cloud</span> Climatology for Land Stations Worldwide, 1971-2009 (NDP-026D)</span></a></p> <p><a target="_blank" href="http://www.osti.gov/dataexplorer">DOE Data Explorer</a></p> <p>Hahn, C. J. [University of Arizona; Warren, S. G. [University of Washington; Eastman, R. [University of Washington</p> <p>2012-08-01</p> <p>Surface synoptic weather reports for 39 years have been processed to provide a climatology of <span class="hlt">clouds</span> for each of over 5000 land-based weather stations with long periods of record both day and night. For each station, this digital archive includes: multi-year annual, seasonal and monthly averages for day and night separately; seasonal and monthly averages by year; averages for eight times per day; and analyses of the first harmonic for the annual and diurnal cycles. Averages are given for total <span class="hlt">cloud</span> cover, clear-sky frequency, and 9 <span class="hlt">cloud</span> types: 5 in the low level (fog, St, Sc, Cu, Cb), 3 in the <span class="hlt">middle</span> level (Ns, As, Ac) and one in the high level (all cirriform <span class="hlt">clouds</span> combined). <span class="hlt">Cloud</span> amounts and frequencies of occurrence are given for all types. In addition, non-overlapped amounts are given for <span class="hlt">middle</span> and high <span class="hlt">cloud</span> types, and average base heights are given for low <span class="hlt">cloud</span> types. Nighttime averages were obtained by using only those reports that met an "illuminance criterion" (i.e., made under adequate moonlight or twilight), thus making possible the determination of diurnal cycles and nighttime trends for <span class="hlt">cloud</span> types.The authors have also produced an online, gridded atlas of the <span class="hlt">cloud</span> observations contained in NDP-026D. The Online <span class="hlt">Cloud</span> Atlas containing NDP-026D data is available via the University of Washington.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19790013548','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19790013548"><span>Insitu aircraft verification of the quality of satellite <span class="hlt">cloud</span> winds over oceanic regions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hasler, A. F.; Skillman, W. C.</p> <p>1979-01-01</p> <p>A five year aircraft experiment to verify the quality of satellite <span class="hlt">cloud</span> winds over oceans using in situ aircraft inertial navigation system wind measurements is presented. The final results show that satellite measured cumulus <span class="hlt">cloud</span> motions are very good estimators of the <span class="hlt">cloud</span> base wind for trade wind and subtropical high regions. The average magnitude of the vector differences between the <span class="hlt">cloud</span> motion and the <span class="hlt">cloud</span> base wind is given. For cumulus <span class="hlt">clouds</span> near frontal regions, the <span class="hlt">cloud</span> motion agreed best with the mean <span class="hlt">cloud</span> <span class="hlt">layer</span> wind. For a very limited sample, cirrus <span class="hlt">cloud</span> motions also most closely followed the mean wind in the <span class="hlt">cloud</span> <span class="hlt">layer</span>.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_15 --> <div id="page_16" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="301"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014GeoRL..41.1681L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014GeoRL..41.1681L"><span>Observed linkages between the northern annular mode/North Atlantic Oscillation, <span class="hlt">cloud</span> incidence, and <span class="hlt">cloud</span> radiative forcing</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Li, Ying; Thompson, David W. J.; Huang, Yi; Zhang, Minghong</p> <p>2014-03-01</p> <p>The signature of the northern annular mode/North Atlantic Oscillation (NAM/NAO) in the vertical and horizontal distribution of tropospheric cloudiness is investigated in <span class="hlt">Cloud</span>Sat and CALIPSO data from June 2006 to April 2011. During the Northern Hemisphere winter, the positive polarity of the NAM/NAO is marked by increases in zonally averaged <span class="hlt">cloud</span> incidence north of ~60°N, decreases between ~25 and 50°N, and increases in the subtropics. The tripolar-like anomalies in <span class="hlt">cloud</span> incidence associated with the NAM/NAO are largest over the North Atlantic Ocean basin/<span class="hlt">Middle</span> East and are physically consistent with the NAM/NAO-related anomalies in vertical motion. Importantly, the NAM/NAO-related anomalies in tropospheric <span class="hlt">cloud</span> incidence lead to significant top of atmosphere <span class="hlt">cloud</span> radiative forcing anomalies that are comparable in amplitude to those associated with the NAM/NAO-related temperature anomalies. The results provide observational evidence that the most prominent pattern of Northern Hemisphere climate variability is significantly linked to variations in <span class="hlt">cloud</span> radiative forcing. Implications for two-way feedback between extratropical dynamics and <span class="hlt">cloud</span> radiative forcing are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AMT....10..221B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AMT....10..221B"><span>Observing relationships between lightning and <span class="hlt">cloud</span> profiles by means of a satellite-borne <span class="hlt">cloud</span> radar</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Buiat, Martina; Porcù, Federico; Dietrich, Stefano</p> <p>2017-01-01</p> <p><span class="hlt">Cloud</span> electrification and related lightning activity in thunderstorms have their origin in the charge separation and resulting distribution of charged iced particles within the <span class="hlt">cloud</span>. So far, the ice distribution within convective <span class="hlt">clouds</span> has been investigated mainly by means of ground-based meteorological radars. In this paper we show how the products from <span class="hlt">Cloud</span> Profiling Radar (CPR) on board <span class="hlt">Cloud</span>Sat, a polar satellite of NASA's Earth System Science Pathfinder (ESSP), can be used to obtain information from space on the vertical distribution of ice particles and ice content and relate them to the lightning activity. The analysis has been carried out, focusing on 12 convective events over Italy that crossed <span class="hlt">Cloud</span>Sat overpasses during significant lightning activity. The CPR products considered here are the vertical profiles of <span class="hlt">cloud</span> ice water content (IWC) and the effective radius (ER) of ice particles, which are compared with the number of strokes as measured by a ground lightning network (LINET). Results show a strong correlation between the number of strokes and the vertical distribution of ice particles as depicted by the 94 GHz CPR products: in particular, <span class="hlt">cloud</span> upper and <span class="hlt">middle</span> levels, high IWC content and relatively high ER seem to be favourable contributory causes for CG (<span class="hlt">cloud</span> to ground) stroke occurrence.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.A51A0017M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.A51A0017M"><span>A multi-spectral approach to simultaneously retrieve above-<span class="hlt">cloud</span> smoke optical depth and the optical and microphysical properties of underlying marine stratocumulus <span class="hlt">clouds</span> using MODIS</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Meyer, K.; Platnick, S. E.; Zhang, Z.</p> <p>2013-12-01</p> <p><span class="hlt">Clouds</span>, 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 <span class="hlt">layer</span> (MBL) <span class="hlt">clouds</span> over the southeastern Atlantic Ocean, which underlie a near-persistent smoke <span class="hlt">layer</span> produced from extensive biomass burning throughout the southern African savanna during austral winter. The absorption of the above-<span class="hlt">cloud</span> smoke <span class="hlt">layer</span>, which increases with decreasing wavelength, can introduce biases into the standard MODIS <span class="hlt">cloud</span> optical and microphysical property retrievals of the underlying MBL <span class="hlt">clouds</span>. This effect is more pronounced in the <span class="hlt">cloud</span> optical thickness retrievals, which over ocean are derived from the wavelength channel centered near 0.86 μm (effective particle size retrievals are derived from the short and mid-wave IR channels at 1.6, 2.1, and 3.7 μm). Here, a new method is introduced to simultaneously retrieve the above-<span class="hlt">cloud</span> smoke aerosol optical depth (AOD) and the unbiased <span class="hlt">cloud</span> optical thickness (COT) and effective radius (CER) using multiple MODIS spectral channels in the visible and near- and shortwave-infrared. Preliminary retrieval results are shown, as are comparisons with other A-Train sensors.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA10076&hterms=ammonia&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dammonia','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA10076&hterms=ammonia&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dammonia"><span>Ammonia Ice <span class="hlt">Clouds</span> on Jupiter</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2007-01-01</p> <p><p/> The top <span class="hlt">cloud</span> <span class="hlt">layer</span> on Jupiter is thought to consist of ammonia ice, but most of that ammonia 'hides' from spectrometers. It does not absorb light in the same way ammonia does. To many scientists, this implies that ammonia churned up from lower <span class="hlt">layers</span> of the atmosphere 'ages' in some way after it condenses, possibly by being covered with a photochemically generated hydrocarbon mixture. The New Horizons Linear Etalon Imaging Spectral Array (LEISA), the half of the Ralph instrument that is able to 'see' in infrared wavelengths that are absorbed by ammonia ice, spotted these <span class="hlt">clouds</span> and watched them evolve over five Jupiter days (about 40 Earth hours). In these images, spectroscopically identified fresh ammonia <span class="hlt">clouds</span> are shown in bright blue. The largest <span class="hlt">cloud</span> appeared as a localized source on day 1, intensified and broadened on day 2, became more diffuse on days 3 and 4, and disappeared on day 5. The diffusion seemed to follow the movement of a dark spot along the boundary of the oval region. Because the source of this ammonia lies deeper than the <span class="hlt">cloud</span>, images like these can tell scientists much about the dynamics and heat conduction in Jupiter's lower atmosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19890024235&hterms=astronomia+espacio&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dastronomia%2By%2Bespacio','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19890024235&hterms=astronomia+espacio&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dastronomia%2By%2Bespacio"><span>On the origin of the Orion and Monoceros molecular <span class="hlt">cloud</span> complexes</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Franco, J.; Tenorio-Tagle, G.; Bodenheimer, P.; Rozyczka, M.; Mirabel, I. F.</p> <p>1988-01-01</p> <p>A detailed model for the origin of the Orion and Monoceros <span class="hlt">cloud</span> complexes is presented, showing that a single high-velocity H I <span class="hlt">cloud</span>-galaxy collision can explain their main observed features. The collision generates massive shocked <span class="hlt">layers</span>, and self-gravity can then provide the conditions for the transformation of these <span class="hlt">layers</span> into molecular <span class="hlt">clouds</span>. The <span class="hlt">clouds</span> formed by the collision maintain the motion of their parental shocked gas and reach positions located far away from the plane. According to this model, both the Orion and Monoceros complexes were formed some 60 million yr ago, when the original shocked <span class="hlt">layer</span> was fragmented by Galactic tidal forces.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017ACP....17.9797S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017ACP....17.9797S"><span>Top-down and bottom-up aerosol-<span class="hlt">cloud</span> closure: towards understanding sources of uncertainty in deriving <span class="hlt">cloud</span> shortwave radiative flux</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sanchez, Kevin J.; Roberts, Gregory C.; Calmer, Radiance; Nicoll, Keri; Hashimshoni, Eyal; Rosenfeld, Daniel; Ovadnevaite, Jurgita; Preissler, Jana; Ceburnis, Darius; O'Dowd, Colin; Russell, Lynn M.</p> <p>2017-08-01</p> <p>, satellite-derived <span class="hlt">cloud</span> droplet number concentrations (CDNCs) were within 30 % of simulated CDNC. In cases with a well-mixed boundary <span class="hlt">layer</span>, δRF is no greater than 20 W m-2 after accounting for <span class="hlt">cloud</span>-top entrainment and up to 50 W m-2 when entrainment is not taken into account. In cases with a decoupled boundary <span class="hlt">layer</span>, <span class="hlt">cloud</span> microphysical properties are inconsistent with ground-based aerosol measurements, as expected, and δRF is as high as 88 W m-2, even high (> 30 W m-2) after accounting for <span class="hlt">cloud</span>-top entrainment. This work demonstrates the need to take in situ measurements of aerosol properties for cases where the boundary <span class="hlt">layer</span> is decoupled as well as consider <span class="hlt">cloud</span>-top entrainment to accurately model stratocumulus <span class="hlt">cloud</span> radiative flux. 1The regulatory term for UAV is remotely piloted aircraft (RPA).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20080014145','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20080014145"><span>Integrated <span class="hlt">Cloud</span>-Aerosol-Radiation Product using CERES, MODIS, CALIPSO and <span class="hlt">Cloud</span>Sat Data</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Sun-Mack, Sunny; Minnis, Patrick; Chen, Yan; Gibson, Sharon; Yi, Yuhong; Trepte, Qing; Wielicki, Bruce; Kato, Seiji; Winker, Dave</p> <p>2007-01-01</p> <p>This paper documents the development of the first integrated data set of global vertical profiles of <span class="hlt">clouds</span>, aerosols, and radiation using the combined NASA A-Train data from the Aqua <span class="hlt">Clouds</span> and Earth's Radiant Energy System (CERES) and Moderate Resolution Imaging Spectroradiometer (MODIS), <span class="hlt">Cloud</span>-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO), and <span class="hlt">Cloud</span>Sat. As part of this effort, <span class="hlt">cloud</span> data from the CALIPSO lidar and the <span class="hlt">Cloud</span>Sat radar are merged with the integrated column <span class="hlt">cloud</span> properties from the CERES-MODIS analyses. The active and passive datasets are compared to determine commonalities and differences in order to facilitate the development of a 3- dimensional <span class="hlt">cloud</span> and aerosol dataset that will then be integrated into the CERES broadband radiance footprint. Preliminary results from the comparisons for April 2007 reveal that the CERES-MODIS global <span class="hlt">cloud</span> amounts are, on average, 0.14 less and 0.15 greater than those from CALIPSO and <span class="hlt">Cloud</span>Sat, respectively. These new data will provide unprecedented ability to test and improve global <span class="hlt">cloud</span> and aerosol models, to investigate aerosol direct and indirect radiative forcing, and to validate the accuracy of global aerosol, <span class="hlt">cloud</span>, and radiation data sets especially in polar regions and for multi-<span class="hlt">layered</span> <span class="hlt">cloud</span> conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007SPIE.6745E..13S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007SPIE.6745E..13S"><span>Integrated <span class="hlt">cloud</span>-aerosol-radiation product using CERES, MODIS, CALIPSO, and <span class="hlt">Cloud</span>Sat data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sun-Mack, Sunny; Minnis, Patrick; Chen, Yan; Gibson, Sharon; Yi, Yuhong; Trepte, Qing; Wielicki, Bruce; Kato, Seiji; Winker, Dave; Stephens, Graeme; Partain, Philip</p> <p>2007-10-01</p> <p>This paper documents the development of the first integrated data set of global vertical profiles of <span class="hlt">clouds</span>, aerosols, and radiation using the combined NASA A-Train data from the Aqua <span class="hlt">Clouds</span> and Earth's Radiant Energy System (CERES) and Moderate Resolution Imaging Spectroradiometer (MODIS), <span class="hlt">Cloud</span>-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO), and <span class="hlt">Cloud</span>Sat. As part of this effort, <span class="hlt">cloud</span> data from the CALIPSO lidar and the <span class="hlt">Cloud</span>Sat radar are merged with the integrated column <span class="hlt">cloud</span> properties from the CERES-MODIS analyses. The active and passive datasets are compared to determine commonalities and differences in order to facilitate the development of a 3-dimensional <span class="hlt">cloud</span> and aerosol dataset that will then be integrated into the CERES broadband radiance footprint. Preliminary results from the comparisons for April 2007 reveal that the CERES-MODIS global <span class="hlt">cloud</span> amounts are, on average, 0.14 less and 0.15 greater than those from CALIPSO and <span class="hlt">Cloud</span>Sat, respectively. These new data will provide unprecedented ability to test and improve global <span class="hlt">cloud</span> and aerosol models, to investigate aerosol direct and indirect radiative forcing, and to validate the accuracy of global aerosol, <span class="hlt">cloud</span>, and radiation data sets especially in polar regions and for multi-<span class="hlt">layered</span> <span class="hlt">cloud</span> conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.P33C2898H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.P33C2898H"><span>Warming ancient Mars with water <span class="hlt">clouds</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hartwick, V.; Toon, B.</p> <p>2017-12-01</p> <p>High <span class="hlt">clouds</span> in the present day Mars atmosphere nucleate on interplanetary dust particles (IDPs) that burn up on entry into the Mars atmosphere. <span class="hlt">Clouds</span> form when superstaturated water vapor condenses on suspended aerosols. Radiatively active water ice <span class="hlt">clouds</span> may play a crucial role in warming the early Mars climate. Urata and Toon (2011) simulate a stable warm paleo-climate for Mars if <span class="hlt">clouds</span> form high in the atmosphere and if particles are sufficiently large (r > 10 μm). The annual fluence of micrometeoroids at Mars was larger early on in the evolution of our solar system. Additionally, the water vapor budget throughout the <span class="hlt">middle</span> and high atmosphere was likely heightened . Both factors should contribute to enhanced nucleation and growth of water ice <span class="hlt">cloud</span> particles at high altitudes. Here, we use the MarsCAM-CARMA general circulation model (GCM) to examine the radiative impact of high altitude water ice <span class="hlt">clouds</span> on the early Mars climate and as a possible solution to the faint young sun problem for Mars.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007AGUFM.A14A..06Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AGUFM.A14A..06Y"><span>Global Distribution and Vertical Structure of <span class="hlt">Clouds</span> Revealed by CALIPSO</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yi, Y.; Minnis, P.; Winker, D.; Huang, J.; Sun-Mack, S.; Ayers, K.</p> <p>2007-12-01</p> <p>Understanding the effects of <span class="hlt">clouds</span> on Earth's radiation balance, especially on longwave fluxes within the atmosphere, depends on having accurate knowledge of <span class="hlt">cloud</span> vertical location within the atmosphere. The <span class="hlt">Cloud</span>- Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite mission provides the opportunity to measure the vertical distribution of <span class="hlt">clouds</span> at a greater detail than ever before possible. The CALIPSO <span class="hlt">cloud</span> <span class="hlt">layer</span> products from June 2006 to June 2007 are analyzed to determine the occurrence frequency and thickness of <span class="hlt">clouds</span> as functions of time, latitude, and altitude. In particular, the latitude-longitude and vertical distributions of single- and multi-<span class="hlt">layer</span> <span class="hlt">clouds</span> and the latitudinal movement of <span class="hlt">cloud</span> cover with the changing seasons are examined. The seasonal variablities of <span class="hlt">cloud</span> frequency and geometric thickness are also analyzed and compared with similar quantities derived from the Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) using the <span class="hlt">Clouds</span> and the Earth's Radiant Energy System (CERES) <span class="hlt">cloud</span> retrieval algorithms. The comparisons provide an estimate of the errors in <span class="hlt">cloud</span> fraction, top height, and thickness incurred by passive algorithms.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20170003310','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20170003310"><span>Saharan Dust as a Causal Factor of Significant <span class="hlt">Cloud</span> Cover Along the Saharan Air <span class="hlt">Layer</span> in the Atlantic Ocean</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kishcha, Pavel; Da Silva, Arlindo M.; Starobinet, Boris; Alpert, Pinhas</p> <p>2016-01-01</p> <p>The tropical Atlantic is frequently affected by Saharan dust intrusions. Based on MODIS <span class="hlt">cloud</span> fraction (CF) data during the ten-year study period, we found that these dust intrusions contribute to significant <span class="hlt">cloud</span> cover along the Saharan Air <span class="hlt">Layer</span> (SAL). Below the temperature inversion at the SAL's base, the presence of large amounts of settling dust particles, together with marine aerosols, produces meteorological conditions suitable for the formation of shallow stratocumulus <span class="hlt">clouds</span>. The significant <span class="hlt">cloud</span> fraction along the SAL together with <span class="hlt">clouds</span> over the Atlantic Inter-tropical Convergence Zone contributes to the 20% hemispheric CF asymmetry between the tropical North and South Atlantic. This leads to the imbalance in strong solar radiation, which reaches the sea surface between the tropical North and South Atlantic, and, consequently, affects climate formation in the tropical Atlantic. Therefore, despite the fact that, over the global ocean, there is no noticeable hemispheric asymmetry in <span class="hlt">cloud</span> fraction, over the significant area such as the tropical Atlantic the hemispheric asymmetry in CF takes place. Saharan dust is also the major contributor to hemispheric aerosol asymmetry over the tropical Atlantic. The NASA GEOS-5 model with aerosol data assimilation was used to extend the MERRA reanalysis with five atmospheric aerosol species (desert dust, sulfates, organic carbon, black carbon, and sea-salt). The obtained ten-year (2002 - 2012) MERRA-driven aerosol reanalysis dataset (aka MERRAero) showed that, over the tropical Atlantic, dust and carbonaceous aerosols were distributed asymmetrically relative to the equator, while other aerosol species were distributed more symmetrically.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19870013880','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19870013880"><span>Double <span class="hlt">Layers</span> in Astrophysics</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Williams, Alton C. (Editor); Moorehead, Tauna W. (Editor)</p> <p>1987-01-01</p> <p>Topics addressed include: laboratory double <span class="hlt">layers</span>; ion-acoustic double <span class="hlt">layers</span>; pumping potential wells; ion phase-space vortices; weak double <span class="hlt">layers</span>; electric fields and double <span class="hlt">layers</span> in plasmas; auroral double <span class="hlt">layers</span>; double <span class="hlt">layer</span> formation in a plasma; beamed emission from gamma-ray burst source; double <span class="hlt">layers</span> and extragalactic jets; and electric potential between plasma sheet <span class="hlt">clouds</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4949710','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4949710"><span>The near‐global mesospheric potassium <span class="hlt">layer</span>: Observations and modeling</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Dawkins, E. C. M.; Chipperfield, M. P.; Feng, W.</p> <p>2015-01-01</p> <p>Abstract The meteoric metal <span class="hlt">layers</span> act as unique tracers of chemistry and dynamics in the upper atmosphere. Existing lidar studies from a few locations show that K exhibits a semiannual seasonality (winter and summer maxima), quite unlike the annual seasonality (winter maximum and summer minimum) seen with Na and Fe. This work uses spaceborne observations made with the Optical Spectrograph and InfraRed Imager System instrument on the Odin satellite to retrieve the near‐global K <span class="hlt">layer</span> for the first time. The satellite data (2004 to mid‐2013) are used to validate the implementation of a recently proposed potassium chemistry scheme in a whole atmosphere chemistry climate model, which provides a chemical basis for this semiannual seasonal behavior. The satellite and model data show that this semiannual seasonality is near global in extent, with the strongest variation at <span class="hlt">middle</span> and high latitudes. The column abundance, centroid <span class="hlt">layer</span> height, and root‐mean‐square width of the K <span class="hlt">layer</span> are consistent with the limited available lidar record. The K data set is then used to investigate the impact of polar mesospheric <span class="hlt">clouds</span> on the metal <span class="hlt">layers</span> at high latitudes during summer. Finally, the occurrence frequency of sporadic K <span class="hlt">layers</span> and their possible link to sporadic E <span class="hlt">layers</span> are examined. PMID:27478716</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012JGRD..11712210K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012JGRD..11712210K"><span>An assessment of the <span class="hlt">cloud</span> signals simulated by NICAM using ISCCP, CALIPSO, and <span class="hlt">Cloud</span>Sat satellite simulators</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kodama, C.; Noda, A. T.; Satoh, M.</p> <p>2012-06-01</p> <p>This study presents an assessment of three-dimensional structures of hydrometeors simulated by the NICAM, global nonhydrostatic atmospheric model without cumulus parameterization, using multiple satellite data sets. A satellite simulator package (COSP: the CFMIP Observation Simulator Package) is employed to consistently compare model output with ISCCP, CALIPSO, and <span class="hlt">Cloud</span>Sat satellite observations. Special focus is placed on high thin <span class="hlt">clouds</span>, which are not observable in the conventional ISCCP data set, but can be detected by the CALIPSO observations. For the control run, the NICAM simulation qualitatively captures the geographical distributions of the high, <span class="hlt">middle</span>, and low <span class="hlt">clouds</span>, even though the horizontal mesh spacing is as coarse as 14 km. The simulated low <span class="hlt">cloud</span> is very close to that of the CALIPSO low <span class="hlt">cloud</span>. Both the <span class="hlt">Cloud</span>Sat observations and NICAM simulation show a boomerang-type pattern in the radar reflectivity-height histogram, suggesting that NICAM realistically simulates the deep <span class="hlt">cloud</span> development process. A striking difference was found in the comparisons of high thin cirrus, showing overestimated <span class="hlt">cloud</span> and higher <span class="hlt">cloud</span> top in the model simulation. Several model sensitivity experiments are conducted with different <span class="hlt">cloud</span> microphysical parameters to reduce the model-observation discrepancies in high thin cirrus. In addition, relationships among <span class="hlt">clouds</span>, Hadley circulation, outgoing longwave radiation and precipitation are discussed through the sensitivity experiments.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://eric.ed.gov/?q=NASA&id=EJ944030','ERIC'); return false;" href="https://eric.ed.gov/?q=NASA&id=EJ944030"><span><span class="hlt">Cloud</span> Study Investigators: Using NASA's CERES S'COOL in Problem-Based Learning</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Moore, Susan; Popiolkowski, Gary</p> <p>2011-01-01</p> <p>1This article describes how, by incorporating NASA's Students' <span class="hlt">Cloud</span> Observations On-Line (S'COOL) project into a problem-based learning (PBL) activity, <span class="hlt">middle</span> school students are engaged in authentic scientific research where they observe and record information about <span class="hlt">clouds</span> and contribute ground truth data to NASA's <span class="hlt">Clouds</span> and the Earth's…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMGC13J0868B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMGC13J0868B"><span><span class="hlt">Cloud</span> fraction and <span class="hlt">cloud</span> base measurements from scanning Doppler lidar during WFIP-2</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bonin, T.; Long, C.; Lantz, K. O.; Choukulkar, A.; Pichugina, Y. L.; McCarty, B.; Banta, R. M.; Brewer, A.; Marquis, M.</p> <p>2017-12-01</p> <p>The second Wind Forecast Improvement Project (WFIP-2) consisted of an 18-month field deployment of a variety of instrumentation with the principle objective of validating and improving NWP forecasts for wind energy applications in complex terrain. As a part of the set of instrumentation, several scanning Doppler lidars were installed across the study domain to primarily measure profiles of the mean wind and turbulence at high-resolution within the planetary boundary <span class="hlt">layer</span>. In addition to these measurements, Doppler lidar observations can be used to directly quantify the <span class="hlt">cloud</span> fraction and <span class="hlt">cloud</span> base, since <span class="hlt">clouds</span> appear as a high backscatter return. These supplementary measurements of <span class="hlt">clouds</span> can then be used to validate <span class="hlt">cloud</span> cover and other properties in NWP output. Herein, statistics of the <span class="hlt">cloud</span> fraction and <span class="hlt">cloud</span> base height from the duration of WFIP-2 are presented. Additionally, these <span class="hlt">cloud</span> fraction estimates from Doppler lidar are compared with similar measurements from a Total Sky Imager and Radiative Flux Analysis (RadFlux) retrievals at the Wasco site. During mostly cloudy to overcast conditions, estimates of the <span class="hlt">cloud</span> radiating temperature from the RadFlux methodology are also compared with Doppler lidar measured <span class="hlt">cloud</span> base height.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19860018364','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19860018364"><span>Senstitivity analysis of horizontal heat and vapor transfer coefficients for a <span class="hlt">cloud</span>-topped marine boundary <span class="hlt">layer</span> during cold-air outbreaks. M.S. Thesis</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Chang, Y. V.</p> <p>1986-01-01</p> <p>The effects of external parameters on the surface heat and vapor fluxes into the marine atmospheric boundary <span class="hlt">layer</span> (MABL) during cold-air outbreaks are investigated using the numerical model of Stage and Businger (1981a). These fluxes are nondimensionalized using the horizontal heat (g1) and vapor (g2) transfer coefficient method first suggested by Chou and Atlas (1982) and further formulated by Stage (1983a). In order to simplify the problem, the boundary <span class="hlt">layer</span> is assumed to be well mixed and horizontally homogeneous, and to have linear shoreline soundings of equivalent potential temperature and mixing ratio. Modifications of initial surface flux estimates, time step limitation, and termination conditions are made to the MABL model to obtain accurate computations. The dependence of g1 and g2 in the <span class="hlt">cloud</span> topped boundary <span class="hlt">layer</span> on the external parameters (wind speed, divergence, sea surface temperature, radiative sky temperature, <span class="hlt">cloud</span> top radiation cooling, and initial shoreline soundings of temperature, and mixing ratio) is studied by a sensitivity analysis, which shows that the uncertainties of horizontal transfer coefficients caused by changes in the parameters are reasonably small.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19950028440&hterms=moisture+condensation&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dmoisture%2Bcondensation','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950028440&hterms=moisture+condensation&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dmoisture%2Bcondensation"><span>Parameterization of bulk condensation in numerical <span class="hlt">cloud</span> models</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kogan, Yefim L.; Martin, William J.</p> <p>1994-01-01</p> <p>The accuracy of the moist saturation adjustment scheme has been evaluated using a three-dimensional explicit microphysical <span class="hlt">cloud</span> model. It was found that the error in saturation adjustment depends strongly on the <span class="hlt">Cloud</span> Condensation Nucleii (CCN) concentration in the ambient atmosphere. The scheme provides rather accurate results in the case where a sufficiently large number of CCN (on the order of several hundred per cubic centimeter) is available. However, under conditions typical of marine stratocumulus <span class="hlt">cloud</span> <span class="hlt">layers</span> with low CCN concentration, the error in the amounts of condensed water vapor and released latent heat may be as large as 40%-50%. A revision of the saturation adjustment scheme is devised that employs the CCN concentration, dynamical supersaturation, and <span class="hlt">cloud</span> water content as additional variables in the calculation of the condensation rate. The revised condensation model reduced the error in maximum updraft and <span class="hlt">cloud</span> water content in the climatically significant case of marine stratocumulus <span class="hlt">cloud</span> <span class="hlt">layers</span> by an order of magnitude.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AtmEn.113....1W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AtmEn.113....1W"><span>Multi-sensor quantification of aerosol-induced variability in warm <span class="hlt">clouds</span> over eastern China</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Fu; Guo, Jianping; Zhang, Jiahua; Huang, Jingfeng; Min, Min; Chen, Tianmeng; Liu, Huan; Deng, Minjun; Li, Xiaowen</p> <p>2015-07-01</p> <p>Aerosol-<span class="hlt">cloud</span> (AC) interactions remain uncharacterized due to difficulties in obtaining accurate aerosol and <span class="hlt">cloud</span> observations. In this study, we quantified the aerosol indirect effects (AIE) on warm <span class="hlt">clouds</span> over Eastern China based on near-simultaneous retrievals from MODIS/AQUA, CALIOP/CALIPSO, and CPR/CLOUDSAT between June 2006 and December 2010. The seasonality of aerosols from ground-based PM10 (aerosol particles with diameter of 10 μm or less) significantly differed from that estimated using MODIS aerosol optical depth (AOD). This result was supported by the lower level frequency profile of aerosol occurrence from CALIOP, indicative of the significant role of CALIOP in the AC interaction. To focus on warm <span class="hlt">clouds</span>, <span class="hlt">cloud</span> <span class="hlt">layers</span> with base (top) altitudes above 7 (10) km were excluded. The combination of CALIOP and CPR was applied to determine the exact position of warm <span class="hlt">clouds</span> relative to aerosols out of the following six scenarios in terms of AC mixing states: 1) aerosol only (AO); 2) <span class="hlt">cloud</span> only (CO); 3) single aerosol <span class="hlt">layer</span>-single <span class="hlt">cloud</span> <span class="hlt">layer</span> (SASC); 4) single aerosol <span class="hlt">layer</span>-double <span class="hlt">cloud</span> <span class="hlt">layers</span> (SADC); 5) double aerosol <span class="hlt">layers</span> - single <span class="hlt">cloud</span> <span class="hlt">layer</span> (DASC); and 6) others. The cases with vertical distance between aerosol and <span class="hlt">cloud</span> <span class="hlt">layer</span> less (more) than 100 m (700 m) were marked mixed (separated), and the rest as uncertain. Results showed that only 8.95% (7.53%) belonged to the mixed (separated and uncertain) state among all of the collocated AC overlapping cases, including SASC, SADC, and DASC. Under mixed conditions, the <span class="hlt">cloud</span> droplet effective radius (CDR) decreased with increasing AOD at moderate aerosol loading (AOD<0.4), and then became saturated at an AOD of around 0.5, followed by an increase in CDR with increasing AOD, known as boomerang shape. Under separated conditions, no apparent changes in CDR with AOD were observed. We categorized the AC dataset into summer- and winter-season subsets to determine how the boomerang shape varied with season. The</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29426185','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29426185"><span>Polycyclic aromatic hydrocarbons (PAHs) associated with PM2.5 within boundary <span class="hlt">layer</span>: <span class="hlt">Cloud</span>/fog and regional transport.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Yang, Minmin; Wang, Yan; Li, Hongli; Li, Tao; Nie, Xiaoling; Cao, Fangfang; Yang, Fengchun; Wang, Zhe; Wang, Tao; Qie, Guanghao; Jin, Tong; Du, Lili; Wang, Wenxing</p> <p>2018-06-15</p> <p>A study of PM 2.5 -associated PAHs analysis at Mount Lushan (1165m) was conducted to investigate the distributions of PAHs in PM 2.5 and influences of <span class="hlt">cloud</span>/fog. The main purpose was to quantify the main emission sources of PAHs and estimate regional transport effects within the boundary <span class="hlt">layer</span>. Mount Lushan is located between the boundary <span class="hlt">layer</span> and troposphere, which is an ideal site for atmosphere transport investigation. The concentrations of PAHs in PM 2.5 were analyzed with GC-MS. The results showed that the volume concentration was 6.98ng/m 3 with a range from 1.47 to 25.17ng/m 3 and PAHs mass were 160.24μg/g (from 63.86 to 427.97μg/g) during the sampling time at Mount Lushan. The dominant compounds are BbF, Pyr and BP. In terms of aromatic-ring PAHs distributions, 4-6-ring PAHs are predominant, indicating that the high-ring PAHs tend to contribute more than low-ring PAHs in particulates. Due to frequent <span class="hlt">cloud</span>/fog days at Mount Lushan, PAHs concentrations in the PM 2.5 were determined before and after <span class="hlt">cloud</span>/fog weather. The results demonstrated that the <span class="hlt">cloud</span>/fog and rain conditions cause lower PAHs levels. Regression analysis was used for studying the relationship of PAHs distributions with meteorological conditions like temperature, humidity and wind. The results showed that the temperature and wind speed were inversely related with PAHs concentration but humidity had no significant relationship. Furthermore, backward trajectories and PCA combined with DR (diagnostic ratio analysis) were employed to identify the influences of regional transport and main emission sources. The results revealed that PAHs in PM 2.5 were mainly affected by regional transport with the main emissions by mobile vehicle and steel industry, which contributed about 56.0% to the total PAHs in the area of Mount Lushan. In addition, backward trajectories revealed that the dominant air masses were from the northwest accounting for about one third of total PAHs. Copyright © 2018</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_16 --> <div id="page_17" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="321"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JGRD..123.3724C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JGRD..123.3724C"><span>The <span class="hlt">Cloud</span> Top Distribution and Diurnal Variation of <span class="hlt">Clouds</span> Over East Asia: Preliminary Results From Advanced Himawari Imager</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chen, Dandan; Guo, Jianping; Wang, Hongqing; Li, Jian; Min, Min; Zhao, Wenhui; Yao, Dan</p> <p>2018-04-01</p> <p><span class="hlt">Clouds</span>, as one of the most uncertain factors in climate system, have been intensively studied as satellites with advanced instruments emerged in recent years. However, few studies examine the vertical distributions of <span class="hlt">cloud</span> top and their temporal variations over East Asia based on geostationary satellite data. In this study, the vertical structures of <span class="hlt">cloud</span> top and its diurnal variations in summer of 2016 are analyzed using the Advanced Himawari Imager/Himawari-8 <span class="hlt">cloud</span> products. Results show that <span class="hlt">clouds</span> occur most frequently over the southern Tibetan Plateau and the Bay of Bengal. We find a steep gradient of <span class="hlt">cloud</span> occurrence frequency extending from southwest to northeast China and low-value centers over the eastern Pacific and the Inner Mongolia Plateau. The vertical structures of <span class="hlt">cloud</span> top are highly dependent on latitude, in addition to the nonnegligible roles of both terrain and land-sea thermal contrast. In terms of the diurnal cycle, <span class="hlt">clouds</span> tend to occur more often in the afternoon, peaking around 1700 local time over land and ocean. The amplitude of <span class="hlt">cloud</span> diurnal variation over ocean is much smaller than that over land, and complex terrain tends to be linked to larger amplitude. In vertical, the diurnal cycle of <span class="hlt">cloud</span> frequency exhibits bimodal pattern over both land and ocean. The high-level peaks occur at almost the same altitude over land and ocean. In contrast, the low-level peaks over ocean mainly reside in the boundary <span class="hlt">layer</span>, much lower than those over land, which could be indicative of the frequent occurrence of marine boundary <span class="hlt">layer</span> <span class="hlt">clouds</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.A54D..01S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.A54D..01S"><span>Aerosol-<span class="hlt">cloud</span> interactions in Arctic mixed-phase stratocumulus</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Solomon, A.</p> <p>2017-12-01</p> <p>Reliable climate projections require realistic simulations of Arctic <span class="hlt">cloud</span> feedbacks. Of particular importance is accurately simulating Arctic mixed-phase stratocumuli (AMPS), which are ubiquitous and play an important role in regional climate due to their impact on the surface energy budget and atmospheric boundary <span class="hlt">layer</span> structure through <span class="hlt">cloud</span>-driven turbulence, radiative forcing, and precipitation. AMPS are challenging to model due to uncertainties in ice microphysical processes that determine phase partitioning between ice and radiatively important <span class="hlt">cloud</span> liquid water. Since temperatures in AMPS are too warm for homogenous ice nucleation, ice must form through heterogeneous nucleation. In this presentation we discuss a relatively unexplored source of ice production-recycling of ice nuclei in regions of ice subsaturation. AMPS frequently have ice-subsaturated air near the <span class="hlt">cloud</span>-driven mixed-<span class="hlt">layer</span> base where falling ice crystals can sublimate, leaving behind IN. This study provides an idealized framework to understand feedbacks between dynamics and microphysics that maintain phase-partitioning in AMPS. In addition, the results of this study provide insight into the mechanisms and feedbacks that may maintain <span class="hlt">cloud</span> ice in AMPS even when entrainment of IN at the mixed-<span class="hlt">layer</span> boundaries is weak.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JGRD..119.6788Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JGRD..119.6788Z"><span>A new <span class="hlt">cloud</span> and aerosol <span class="hlt">layer</span> detection method based on micropulse lidar measurements</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhao, Chuanfeng; Wang, Yuzhao; Wang, Qianqian; Li, Zhanqing; Wang, Zhien; Liu, Dong</p> <p>2014-06-01</p> <p>This paper introduces a new algorithm to detect aerosols and <span class="hlt">clouds</span> based on micropulse lidar measurements. A semidiscretization processing technique is first used to inhibit the impact of increasing noise with distance. The value distribution equalization method which reduces the magnitude of signal variations with distance is then introduced. Combined with empirical threshold values, we determine if the signal waves indicate <span class="hlt">clouds</span> or aerosols. This method can separate <span class="hlt">clouds</span> and aerosols with high accuracy, although differentiation between aerosols and <span class="hlt">clouds</span> are subject to more uncertainties depending on the thresholds selected. Compared with the existing Atmospheric Radiation Measurement program lidar-based <span class="hlt">cloud</span> product, the new method appears more reliable and detects more <span class="hlt">clouds</span> with high bases. The algorithm is applied to a year of observations at both the U.S. Southern Great Plains (SGP) and China Taihu sites. At the SGP site, the <span class="hlt">cloud</span> frequency shows a clear seasonal variation with maximum values in winter and spring and shows bimodal vertical distributions with maximum occurrences at around 3-6 km and 8-12 km. The annual averaged <span class="hlt">cloud</span> frequency is about 50%. The dominant <span class="hlt">clouds</span> are stratiform in winter and convective in summer. By contrast, the <span class="hlt">cloud</span> frequency at the Taihu site shows no clear seasonal variation and the maximum occurrence is at around 1 km. The annual averaged <span class="hlt">cloud</span> frequency is about 15% higher than that at the SGP site. A seasonal analysis of <span class="hlt">cloud</span> base occurrence frequency suggests that stratiform <span class="hlt">clouds</span> dominate at the Taihu site.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20080015852','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20080015852"><span>Determination of Ice Water Path in Ice-over-Water <span class="hlt">Cloud</span> Systems Using Combined MODIS and AMSR-E Measurements</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Huang, Jianping; Minnis, Patrick; Lin, Bing; Yi, Yuhong; Fan, T.-F.; Sun-Mack, Sunny; Ayers, J. K.</p> <p>2006-01-01</p> <p>To provide more accurate ice <span class="hlt">cloud</span> properties for evaluating climate models, the updated version of multi-<span class="hlt">layered</span> <span class="hlt">cloud</span> retrieval system (MCRS) is used to retrieve ice water path (IWP) in ice-over-water <span class="hlt">cloud</span> systems over global ocean using combined instrument data from the Aqua satellite. The liquid water path (LWP) of lower <span class="hlt">layer</span> water <span class="hlt">clouds</span> is estimated from the Advanced Microwave Scanning Radiometer for EOS (AMSR-E) measurements. With the lower <span class="hlt">layer</span> LWP known, the properties of the upper-level ice <span class="hlt">clouds</span> are then derived from Moderate Resolution Imaging Spectroradiometer measurements by matching simulated radiances from a two-<span class="hlt">cloud</span> <span class="hlt">layer</span> radiative transfer model. Comparisons with single-<span class="hlt">layer</span> cirrus systems and surface-based radar retrievals show that the MCRS can significantly improve the accuracy and reduce the over-estimation of optical depth and ice water path retrievals for ice over-water <span class="hlt">cloud</span> systems. During the period from December 2004 through February 2005, the mean daytime ice <span class="hlt">cloud</span> optical depth and IWP for overlapped ice-over-water <span class="hlt">clouds</span> over ocean from Aqua are 7.6 and 146.4 gm(sup -2), respectively, significantly less than the initial single <span class="hlt">layer</span> retrievals of 17.3 and 322.3 gm(sup -2). The mean IWP for actual single-<span class="hlt">layer</span> <span class="hlt">clouds</span> was 128.2 gm(sup -2).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017GeoRL..44.5774N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017GeoRL..44.5774N"><span>A <span class="hlt">cloud</span>-resolving model study of aerosol-<span class="hlt">cloud</span> correlation in a pristine maritime environment</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nishant, Nidhi; Sherwood, Steven C.</p> <p>2017-06-01</p> <p>In convective <span class="hlt">clouds</span>, satellite-observed deepening or increased amount of <span class="hlt">clouds</span> with increasing aerosol concentration has been reported and is sometimes interpreted as aerosol-induced invigoration of the <span class="hlt">clouds</span>. However, such correlations can be affected by meteorological factors that affect both aerosol and <span class="hlt">clouds</span>, as well as observational issues. In this study, we examine the behavior in a 660 × 660 km2 region of the South Pacific during June 2007, previously found by Koren et al. (2014) to show strong correlation between <span class="hlt">cloud</span> fraction, <span class="hlt">cloud</span> top pressure, and aerosols, using a <span class="hlt">cloud</span>-resolving model with meteorological boundary conditions specified from a reanalysis. The model assumes constant aerosol loading, yet reproduces vigorous <span class="hlt">clouds</span> at times of high real-world aerosol concentrations. Days with high- and low-aerosol loading exhibit deep-convective and shallow <span class="hlt">clouds</span>, respectively, in both observations and the simulation. Synoptic analysis shows that vigorous <span class="hlt">clouds</span> occur at times of strong surface troughs, which are associated with high winds and advection of boundary <span class="hlt">layer</span> air from the Southern Ocean where sea-salt aerosol is abundant, thus accounting for the high correlation. Our model results show that aerosol-<span class="hlt">cloud</span> relationships can be explained by coexisting but independent wind-aerosol and wind-<span class="hlt">cloud</span> relationships and that no <span class="hlt">cloud</span> condensation nuclei effect is required.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1423787-diurnal-cycle-clouds-precipitation-arm-sgp-site-cloud-radar-observations-simulations-from-multiscale-modeling-framework','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1423787-diurnal-cycle-clouds-precipitation-arm-sgp-site-cloud-radar-observations-simulations-from-multiscale-modeling-framework"><span>The diurnal cycle of <span class="hlt">clouds</span> and precipitation at the ARM SGP site: <span class="hlt">Cloud</span> radar observations and simulations from the multiscale modeling framework</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Zhao, Wei; Marchand, Roger; Fu, Qiang</p> <p>2017-07-08</p> <p>Millimeter Wavelength <span class="hlt">Cloud</span> Radar (MMCR) data from December 1996 to December 2010, collected at the U.S. Department of Energy Atmospheric Radiation Measurement (ARM) program Southern Great Plains (SGP) site, are used to examine the diurnal cycle of hydrometeor occurrence. These data are categorized into <span class="hlt">clouds</span> (-40 dBZ e ≤ reflectivity < -10 dBZ e), drizzle and light precipitation (-10 dBZ e ≤ reflectivity < 10 dBZ e), and heavy precipitation (reflectivity ≥ 10 dBZ e). The same criteria are implemented for the observation-equivalent reflectivity calculated by feeding outputs from a Multiscale Modeling Framework (MMF) climate model into a radar simulator.more » The MMF model consists of the National Center for Atmospheric Research Community Atmosphere Model with conventional <span class="hlt">cloud</span> parameterizations replaced by a <span class="hlt">cloud</span>-resolving model. We find that a radar simulator combined with the simple reflectivity categories can be an effective approach for evaluating diurnal variations in model hydrometeor occurrence. It is shown that the MMF only marginally captures observed increases in the occurrence of boundary <span class="hlt">layer</span> <span class="hlt">clouds</span> after sunrise in spring and autumn and does not capture diurnal changes in boundary <span class="hlt">layer</span> <span class="hlt">clouds</span> during the summer. Above the boundary <span class="hlt">layer</span>, the MMF captures reasonably well diurnal variations in the vertical structure of <span class="hlt">clouds</span> and light and heavy precipitation in the summer but not in the spring.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005JApMe..44...28S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005JApMe..44...28S"><span>An Algorithm for the Retrieval of Droplet Number Concentration and Geometrical Thickness of Stratiform Marine Boundary <span class="hlt">Layer</span> <span class="hlt">Clouds</span> Applied to MODIS Radiometric Observations.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schüller, Lothar; Bennartz, Ralf; Fischer, Jürgen; Brenguier, Jean-Louis</p> <p>2005-01-01</p> <p>Algorithms are now currently used for the retrieval of <span class="hlt">cloud</span> optical thickness and droplet effective radius from multispectral radiance measurements. This paper extends their application to the retrieval of <span class="hlt">cloud</span> droplet number concentration, <span class="hlt">cloud</span> geometrical thickness, and liquid water path in shallow convective <span class="hlt">clouds</span>, using an algorithm that was previously tested with airborne measurements of <span class="hlt">cloud</span> radiances and validated against in situ measurements of the same <span class="hlt">clouds</span>. The retrieval is based on a stratified <span class="hlt">cloud</span> model of liquid water content and droplet spectrum. Radiance measurements in visible and near-infrared channels of the Moderate Resolution Imaging Spectroradiometer (MODIS), which is operated from the NASA platforms Terra and Aqua, are analyzed. Because of uncertainties in the simulation of the continental surface reflectance, the algorithm is presently limited to the monitoring of the microphysical structure of boundary <span class="hlt">layer</span> <span class="hlt">clouds</span> over the ocean. Two MODIS scenes of extended <span class="hlt">cloud</span> fields over the North Atlantic Ocean trade wind region are processed. A transport and dispersion model (the Hybrid Single-Particle Lagrangian Integrated Trajectory Model, HYSPLIT4) is also used to characterize the origin of the air masses and hence their aerosol regimes. One <span class="hlt">cloud</span> field formed in an air mass that was advected from southern Europe and North Africa. It shows high values of the droplet concentration when compared with the second <span class="hlt">cloud</span> system, which developed in a more pristine environment. The more pristine case also exhibits a higher geometrical thickness and, thus, liquid water path, which counterbalances the expected <span class="hlt">cloud</span> albedo increase of the polluted case. Estimates of <span class="hlt">cloud</span> liquid water path are then compared with retrievals from the Special Sensor Microwave Imager (SSM/I). SSM/I-derived liquid water paths are in good agreement with the MODIS-derived values.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008cosp...37.3208T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008cosp...37.3208T"><span>Comparison of <span class="hlt">Cloud</span> and Aerosol Detection between CERES Edition 3 <span class="hlt">Cloud</span> Mask and CALIPSO Version 2 Data Products</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Trepte, Qing; Minnis, Patrick; Sun-Mack, Sunny; Trepte, Charles</p> <p></p> <p><span class="hlt">Clouds</span> and aerosol play important roles in the global climate system. Accurately detecting their presence, altitude, and properties using satellite radiance measurements is a crucial first step in determining their influence on surface and top-of-atmosphere radiative fluxes. This paper presents a comparison analysis of a new version of the <span class="hlt">Clouds</span> and Earth's Radiant Energy System (CERES) Edition 3 <span class="hlt">cloud</span> detection algorithms using Aqua MODIS data with the recently released <span class="hlt">Cloud</span>-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) Version 2 Vertical Feature Mask (VFM). Improvements in CERES Edition 3 <span class="hlt">cloud</span> mask include dust detection, thin cirrus tests, enhanced low <span class="hlt">cloud</span> detection at night, and a smoother transition from mid-latitude to polar regions. For the CALIPSO Version 2 data set, changes to the lidar calibration can result in significant improvements to its identification of optically thick aerosol <span class="hlt">layers</span>. The Aqua and CALIPSO satellites, part of the A-train satellite constellation, provide a unique opportunity for validating passive sensor <span class="hlt">cloud</span> and aerosol detection using an active sensor. In this paper, individual comparison cases will be discussed for different types of <span class="hlt">clouds</span> and aerosols over various surfaces, for daytime and nighttime conditions, and for regions ranging from the tropics to the poles. Examples will include an assessment of the CERES detection algorithm for optically thin cirrus, marine stratus, and polar night <span class="hlt">clouds</span> as well as its ability to characterize Saharan dust plumes off the African coast. With the CALIPSO lidar's unique ability to probe the vertical structure of <span class="hlt">clouds</span> and aerosol <span class="hlt">layers</span>, it provides an excellent validation data set for <span class="hlt">cloud</span> detection algorithms, especially for polar nighttime <span class="hlt">clouds</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1994JGR....9914461L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1994JGR....9914461L"><span>Clustering, randomness, and regularity in <span class="hlt">cloud</span> fields. 4. Stratocumulus <span class="hlt">cloud</span> fields</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lee, J.; Chou, J.; Weger, R. C.; Welch, R. M.</p> <p>1994-07-01</p> <p>To complete the analysis of the spatial distribution of boundary <span class="hlt">layer</span> cloudiness, the present study focuses on nine stratocumulus Landsat scenes. The results indicate many similarities between stratocumulus and cumulus spatial distributions. Most notably, at full spatial resolution all scenes exhibit a decidedly clustered distribution. The strength of the clustering signal decreases with increasing <span class="hlt">cloud</span> size; the clusters themselves consist of a few <span class="hlt">clouds</span> (less than 10), occupy a small percentage of the <span class="hlt">cloud</span> field area (less than 5%), contain between 20% and 60% of the <span class="hlt">cloud</span> field population, and are randomly located within the scene. In contrast, stratocumulus in almost every respect are more strongly clustered than are cumulus <span class="hlt">cloud</span> fields. For instance, stratocumulus clusters contain more <span class="hlt">clouds</span> per cluster, occupy a larger percentage of the total area, and have a larger percentage of <span class="hlt">clouds</span> participating in clusters than the corresponding cumulus examples. To investigate clustering at intermediate spatial scales, the local dimensionality statistic is introduced. Results obtained from this statistic provide the first direct evidence for regularity among large (>900 m in diameter) <span class="hlt">clouds</span> in stratocumulus and cumulus <span class="hlt">cloud</span> fields, in support of the inhibition hypothesis of Ramirez and Bras (1990). Also, the size compensated point-to-<span class="hlt">cloud</span> cumulative distribution function statistic is found to be necessary to obtain a consistent description of stratocumulus <span class="hlt">cloud</span> distributions. A hypothesis regarding the underlying physical mechanisms responsible for <span class="hlt">cloud</span> clustering is presented. It is suggested that <span class="hlt">cloud</span> clusters often arise from 4 to 10 triggering events localized within regions less than 2 km in diameter and randomly distributed within the <span class="hlt">cloud</span> field. As the size of the <span class="hlt">cloud</span> surpasses the scale of the triggering region, the clustering signal weakens and the larger <span class="hlt">cloud</span> locations become more random.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19950045731&hterms=Clustering&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DClustering','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950045731&hterms=Clustering&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DClustering"><span>Clustering, randomness, and regularity in <span class="hlt">cloud</span> fields. 4: Stratocumulus <span class="hlt">cloud</span> fields</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lee, J.; Chou, J.; Weger, R. C.; Welch, R. M.</p> <p>1994-01-01</p> <p>To complete the analysis of the spatial distribution of boundary <span class="hlt">layer</span> cloudiness, the present study focuses on nine stratocumulus Landsat scenes. The results indicate many similarities between stratocumulus and cumulus spatial distributions. Most notably, at full spatial resolution all scenes exhibit a decidedly clustered distribution. The strength of the clustering signal decreases with increasing <span class="hlt">cloud</span> size; the clusters themselves consist of a few <span class="hlt">clouds</span> (less than 10), occupy a small percentage of the <span class="hlt">cloud</span> field area (less than 5%), contain between 20% and 60% of the <span class="hlt">cloud</span> field population, and are randomly located within the scene. In contrast, stratocumulus in almost every respect are more strongly clustered than are cumulus <span class="hlt">cloud</span> fields. For instance, stratocumulus clusters contain more <span class="hlt">clouds</span> per cluster, occupy a larger percentage of the total area, and have a larger percentage of <span class="hlt">clouds</span> participating in clusters than the corresponding cumulus examples. To investigate clustering at intermediate spatial scales, the local dimensionality statistic is introduced. Results obtained from this statistic provide the first direct evidence for regularity among large (more than 900 m in diameter) <span class="hlt">clouds</span> in stratocumulus and cumulus <span class="hlt">cloud</span> fields, in support of the inhibition hypothesis of Ramirez and Bras (1990). Also, the size compensated point-to-<span class="hlt">cloud</span> cumulative distribution function statistic is found to be necessary to obtain a consistent description of stratocumulus <span class="hlt">cloud</span> distributions. A hypothesis regarding the underlying physical mechanisms responsible for <span class="hlt">cloud</span> clustering is presented. It is suggested that <span class="hlt">cloud</span> clusters often arise from 4 to 10 triggering events localized within regions less than 2 km in diameter and randomly distributed within the <span class="hlt">cloud</span> field. As the size of the <span class="hlt">cloud</span> surpasses the scale of the triggering region, the clustering signal weakens and the larger <span class="hlt">cloud</span> locations become more random.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19990028514','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19990028514"><span>FIRE Arctic <span class="hlt">Clouds</span> Experiment</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Curry, J. A.; Hobbs, P. V.; King, M. D.; Randall, D. A.; Minnis, P.; Issac, G. A.; Pinto, J. O.; Uttal, T.; Bucholtz, A.; Cripe, D. G.; <a style="text-decoration: none; " href="javascript:void(0); " onClick="displayelement('author_19990028514'); toggleEditAbsImage('author_19990028514_show'); toggleEditAbsImage('author_19990028514_hide'); "> <img style="display:inline; width:12px; height:12px; " src="images/arrow-up.gif" width="12" height="12" border="0" alt="hide" id="author_19990028514_show"> <img style="width:12px; height:12px; display:none; " src="images/arrow-down.gif" width="12" height="12" border="0" alt="hide" id="author_19990028514_hide"></p> <p>1998-01-01</p> <p>An overview is given of the First ISCCP Regional Experiment (FIRE) Arctic <span class="hlt">Clouds</span> Experiment that was conducted in the Arctic during April through July, 1998. The principal goal of the field experiment was to gather the data needed to examine the impact of arctic <span class="hlt">clouds</span> on the radiation exchange between the surface, atmosphere, and space, and to study how the surface influences the evolution of boundary <span class="hlt">layer</span> <span class="hlt">clouds</span>. The observations will be used to evaluate and improve climate model parameterizations of <span class="hlt">cloud</span> and radiation processes, satellite remote sensing of <span class="hlt">cloud</span> and surface characteristics, and understanding of <span class="hlt">cloud</span>-radiation feedbacks in the Arctic. The experiment utilized four research aircraft that flew over surface-based observational sites in the Arctic Ocean and Barrow, Alaska. In this paper we describe the programmatic and science objectives of the project, the experimental design (including research platforms and instrumentation), conditions that were encountered during the field experiment, and some highlights of preliminary observations, modelling, and satellite remote sensing studies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.A54A..07W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.A54A..07W"><span>Trade cumulus <span class="hlt">clouds</span> embedded in a deep regional haze: Results from Indian Ocean CARDEX experiment</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wilcox, E. M.; Thomas, R. M.; Praveen, P. S.; Pistone, K.; Bender, F.; Feng, Y.; Ramanathan, V.</p> <p>2013-12-01</p> <p>During the winter monsoon, trade cumulus <span class="hlt">clouds</span> over the North Indian Ocean are embedded within a deep regional haze described as an atmospheric brown <span class="hlt">cloud</span>. While the trade-cu <span class="hlt">clouds</span> are largely confined to the marine boundary <span class="hlt">layer</span>, the sooty brown <span class="hlt">cloud</span> extends from the boundary <span class="hlt">layer</span> to as high as 3 km; well above the tops of the cumulus. The boundary <span class="hlt">layer</span> pollution is persistent and limits drizzle in the cumulus over a period of greater than a month at the Maldives Climate Observatory located at Hanimaadhoo Island. The elevated haze from 1 to 3 km altitude is episodic and strongly modulated by synoptic variability in the 700 hPa flow. The elevated plume enhances heating above the marine boundary <span class="hlt">layer</span> through daytime absorption of sunlight by the haze particles. The interplay between the microphysical modification of <span class="hlt">clouds</span> by boundary <span class="hlt">layer</span> pollution and the episodic elevated heating by the atmospheric brown <span class="hlt">cloud</span> are explored in in-situ observations from UAVs and surface remote sensing during the CARDEX field campaign of winter 2012 and supported by multi-year analysis of satellite remote sensing observations. These observations document the variability in pollution at the surface and above the marine boundary <span class="hlt">layer</span> and the effects of pollution on the microphysics of the trade-cu <span class="hlt">clouds</span>, the depth of the marine boundary <span class="hlt">layer</span>, the liquid water path of trade-cu <span class="hlt">clouds</span>, and the profile of turbulent moisture flux through the boundary <span class="hlt">layer</span>. The consequences of these effects for the radiative forcing of regional climate will be discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006GeoRL..3321801H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006GeoRL..3321801H"><span>Determination of ice water path in ice-over-water <span class="hlt">cloud</span> systems using combined MODIS and AMSR-E measurements</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Huang, Jianping; Minnis, Patrick; Lin, Bing; Yi, Yuhong; Fan, T.-F.; Sun-Mack, Sunny; Ayers, J. K.</p> <p>2006-11-01</p> <p>To provide more accurate ice <span class="hlt">cloud</span> microphysical properties, the multi-<span class="hlt">layered</span> <span class="hlt">cloud</span> retrieval system (MCRS) is used to retrieve ice water path (IWP) in ice-over-water <span class="hlt">cloud</span> systems globally over oceans using combined instrument data from Aqua. The liquid water path (LWP) of lower-<span class="hlt">layer</span> water <span class="hlt">clouds</span> is estimated from the Advanced Microwave Scanning Radiometer for EOS (AMSR-E) measurements. The properties of the upper-level ice <span class="hlt">clouds</span> are then derived from Moderate Resolution Imaging Spectroradiometer (MODIS) measurements by matching simulated radiances from a two-<span class="hlt">cloud-layer</span> radiative transfer model. The results show that the MCRS can significantly improve the accuracy and reduce the over-estimation of optical depth and IWP retrievals for ice-over-water <span class="hlt">cloud</span> systems. The mean daytime ice <span class="hlt">cloud</span> optical depth and IWP for overlapped ice-over-water <span class="hlt">clouds</span> over oceans from Aqua are 7.6 and 146.4 gm-2, respectively, down from the initial single-<span class="hlt">layer</span> retrievals of 17.3 and 322.3 gm-2. The mean IWP for actual single-<span class="hlt">layer</span> <span class="hlt">clouds</span> is 128.2 gm-2.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20020080736&hterms=safari&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dsafari','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20020080736&hterms=safari&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dsafari"><span><span class="hlt">Cloud</span> Physics Lidar Optical Measurements During the SAFARI-2000 Field Campaign</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hlavka, Dennis L.; McGill, Matt; Hart, William D.; Spinhirne, James D.; Starr, David OC. (Technical Monitor)</p> <p>2002-01-01</p> <p>In this presentation, we will show new optical data processing results from the <span class="hlt">Cloud</span> Physics War during SAFARI-2000. Retrieved products include aerosol and <span class="hlt">cloud</span> <span class="hlt">layer</span> location and identification, <span class="hlt">layer</span> optical depths, vertical extinction profiles, and extinction-to-backscatter (S) ratios for 532 and 1064 nm. The retrievals will focus on the persistent and smoky planetary boundary <span class="hlt">layer</span> and occasional elevated aerosol <span class="hlt">layers</span> found in southern Africa during August and September 2000.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19990100656','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19990100656"><span>Vertical Photon Transport in <span class="hlt">Cloud</span> Remote Sensing Problems</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Platnick, S.</p> <p>1999-01-01</p> <p>Photon transport in plane-parallel, vertically inhomogeneous <span class="hlt">clouds</span> is investigated and applied to <span class="hlt">cloud</span> remote sensing techniques that use solar reflectance or transmittance measurements for retrieving droplet effective radius. Transport is couched in terms of weighting functions which approximate the relative contribution of individual <span class="hlt">layers</span> to the overall retrieval. Two vertical weightings are investigated, including one based on the average number of scatterings encountered by reflected and transmitted photons in any given <span class="hlt">layer</span>. A simpler vertical weighting based on the maximum penetration of reflected photons proves useful for solar reflectance measurements. These weighting functions are highly dependent on droplet absorption and solar/viewing geometry. A superposition technique, using adding/doubling radiative transfer procedures, is derived to accurately determine both weightings, avoiding time consuming Monte Carlo methods. Superposition calculations are made for a variety of geometries and <span class="hlt">cloud</span> models, and selected results are compared with Monte Carlo calculations. Effective radius retrievals from modeled vertically inhomogeneous liquid water <span class="hlt">clouds</span> are then made using the standard near-infrared bands, and compared with size estimates based on the proposed weighting functions. Agreement between the two methods is generally within several tenths of a micrometer, much better than expected retrieval accuracy. Though the emphasis is on photon transport in <span class="hlt">clouds</span>, the derived weightings can be applied to any multiple scattering plane-parallel radiative transfer problem, including arbitrary combinations of <span class="hlt">cloud</span>, aerosol, and gas <span class="hlt">layers</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19820011747','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19820011747"><span>Methods of editing <span class="hlt">cloud</span> and atmospheric <span class="hlt">layer</span> affected pixels from satellite data</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Nixon, P. R. (Principal Investigator); Wiegand, C. L.; Richardson, A. J.; Johnson, M. P.; Goodier, B. G.</p> <p>1981-01-01</p> <p>The location and migration of <span class="hlt">cloud</span>, land and water features were examined in spectral space (reflective VIS vs. emissive IR). Daytime HCMM data showed two distinct types of <span class="hlt">cloud</span> 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 <span class="hlt">clouds</span>, or of mixed cumulus and landscape, clustered in a different area of spectral space than the high altitude <span class="hlt">cloud</span> pixels. Cumulus affected pixels were more reflective than land and water pixels. In August the high altitude <span class="hlt">clouds</span> and SCi were more emissive than similar <span class="hlt">clouds</span> were in July. Four-channel TIROS-N data were examined with the objective of developing a multispectral screening technique for removing SCi contaminated data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.4537T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.4537T"><span>Contrasting sea-ice and open-water boundary <span class="hlt">layers</span> during melt and freeze-up seasons: Some result from the Arctic <span class="hlt">Clouds</span> in Summer Experiment.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tjernström, Michael; Sotiropoulou, Georgia; Sedlar, Joseph; Achtert, Peggy; Brooks, Barbara; Brooks, Ian; Persson, Ola; Prytherch, John; Salsbury, Dominic; Shupe, Matthew; Johnston, Paul; Wolfe, Dan</p> <p>2016-04-01</p> <p>With more open water present in the Arctic summer, an understanding of atmospheric processes over open-water and sea-ice surfaces as summer turns into autumn and ice starts forming becomes increasingly important. The Arctic <span class="hlt">Clouds</span> in Summer Experiment (ACSE) was conducted in a mix of open water and sea ice in the eastern Arctic along the Siberian shelf during late summer and early autumn 2014, providing detailed observations of the seasonal transition, from melt to freeze. Measurements were taken over both ice-free and ice-covered surfaces, offering an insight to the role of the surface state in shaping the lower troposphere and the boundary-<span class="hlt">layer</span> conditions as summer turned into autumn. During summer, strong surface inversions persisted over sea ice, while well-mixed boundary <span class="hlt">layers</span> capped by elevated inversions were frequent over open-water. The former were often associated with advection of warm air from adjacent open-water or land surfaces, whereas the latter were due to a positive buoyancy flux from the warm ocean surface. Fog and stratus <span class="hlt">clouds</span> often persisted over the ice, whereas low-level liquid-water <span class="hlt">clouds</span> developed over open water. These differences largely disappeared in autumn, when mixed-phase <span class="hlt">clouds</span> capped by elevated inversions dominated in both ice-free and ice-covered conditions. Low-level-jets occurred ~20-25% of the time in both seasons. The observations indicate that these jets were typically initiated at air-mass boundaries or along the ice edge in autumn, while in summer they appeared to be inertial oscillations initiated by partial frictional decoupling as warm air was advected in over the sea ice. The start of the autumn season was related to an abrupt change in atmospheric conditions, rather than to the gradual change in solar radiation. The autumn onset appeared as a rapid cooling of the whole atmosphere and the freeze up followed as the warm surface lost heat to the atmosphere. While the surface type had a pronounced impact on boundary-<span class="hlt">layer</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20070020527&hterms=doi&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Ddoi%253A','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20070020527&hterms=doi&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Ddoi%253A"><span>Multidecadal Changes in Near-Global <span class="hlt">Cloud</span> Cover and Estimated <span class="hlt">Cloud</span> Cover Radiative Forcing</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Norris, Joel</p> <p>2005-01-01</p> <p>The first paper was Multidecadal changes in near-global <span class="hlt">cloud</span> cover and estimated <span class="hlt">cloud</span> cover radiative forcing, by J. R. Norris (2005, J. Geophys. Res. - Atmos., 110, D08206, doi: lO.l029/2004JD005600). This study examined variability in zonal mean surface-observed upper-level (combined midlevel and high-level) and low-level <span class="hlt">cloud</span> cover over land during 1971-1 996 and over ocean during 1952-1997. These data were averaged from individual synoptic reports in the Extended Edited <span class="hlt">Cloud</span> Report Archive (EECRA). Although substantial interdecadal variability is present in the time series, long-term decreases in upper-level <span class="hlt">cloud</span> cover occur over land and ocean at low and <span class="hlt">middle</span> latitudes in both hemispheres. Near-global upper-level <span class="hlt">cloud</span> cover declined by 1.5%-sky-cover over land between 1971 and 1996 and by 1.3%-sky-cover over ocean between 1952 and 1997. Consistency between EECRA upper-level <span class="hlt">cloud</span> cover anomalies and those from the International Satellite <span class="hlt">Cloud</span> Climatology Project (ISCCP) during 1984-1 997 suggests the surface-observed trends are real. The reduction in surface-observed upper-level <span class="hlt">cloud</span> cover between the 1980s and 1990s is also consistent with the decadal increase in all-sky outgoing longwave radiation reported by the Earth Radiation Budget Satellite (EMS). Discrepancies occur between time series of EECRA and ISCCP low-level <span class="hlt">cloud</span> cover due to identified and probable artifacts in satellite and surface <span class="hlt">cloud</span> data. Radiative effects of surface-observed <span class="hlt">cloud</span> cover anomalies, called "<span class="hlt">cloud</span> cover radiative forcing (CCRF) anomalies," are estimated based on a linear relationship to climatological <span class="hlt">cloud</span> radiative forcing per unit <span class="hlt">cloud</span> cover. Zonal mean estimated longwave CCRF has decreased over most of the globe. Estimated shortwave CCRF has become slightly stronger over northern midlatitude oceans and slightly weaker over northern midlatitude land areas. A long-term decline in the magnitude of estimated shortwave CCRF occurs over low-latitude land and ocean</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.A22D..05W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.A22D..05W"><span>A New <span class="hlt">Cloud</span> and Aerosol <span class="hlt">Layer</span> Detection Method Based on Micropulse Lidar Measurements</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Q.; Zhao, C.; Wang, Y.; Li, Z.; Wang, Z.; Liu, D.</p> <p>2014-12-01</p> <p>A new algorithm is developed to detect aerosols and <span class="hlt">clouds</span> based on micropulse lidar (MPL) measurements. In this method, a semi-discretization processing (SDP) technique is first used to inhibit the impact of increasing noise with distance, then a value distribution equalization (VDE) method is introduced to reduce the magnitude of signal variations with distance. Combined with empirical threshold values, <span class="hlt">clouds</span> and aerosols are detected and separated. This method can detect <span class="hlt">clouds</span> and aerosols with high accuracy, although classification of aerosols and <span class="hlt">clouds</span> is sensitive to the thresholds selected. Compared with the existing Atmospheric Radiation Measurement (ARM) program lidar-based <span class="hlt">cloud</span> product, the new method detects more high <span class="hlt">clouds</span>. The algorithm was applied to a year of observations at both the U.S. Southern Great Plains (SGP) and China Taihu site. At SGP, the <span class="hlt">cloud</span> frequency shows a clear seasonal variation with maximum values in winter and spring, and shows bi-modal vertical distributions with maximum frequency at around 3-6 km and 8-12 km. The annual averaged <span class="hlt">cloud</span> frequency is about 50%. By contrast, the <span class="hlt">cloud</span> frequency at Taihu shows no clear seasonal variation and the maximum frequency is at around 1 km. The annual averaged <span class="hlt">cloud</span> frequency is about 15% higher than that at SGP.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.A51I0188M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.A51I0188M"><span>A novel approach to Lagrangian sampling of marine boundary <span class="hlt">layer</span> <span class="hlt">cloud</span> and aerosol in the northeast Pacific: case studies from CSET</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mohrmann, J.; Albrecht, B. A.; Bretherton, C. S.; Ghate, V. P.; Zuidema, P.; Wood, R.</p> <p>2015-12-01</p> <p>The <span class="hlt">Cloud</span> System Evolution in the Trades (CSET) field campaign took place during July/August 2015 with the purpose of characterizing the <span class="hlt">cloud</span>, aerosol and thermodynamic properties of the northeast Pacific marine boundary <span class="hlt">layer</span>. One major science goal of the campaign was to observe a Lagrangian transition from thin stratocumulus (Sc) upwind near California to trade cumulus (Cu) nearer to Hawaii. <span class="hlt">Cloud</span> properties were observed from the NSF/NCAR Gulfstream V research plane (GV) using the HIAPER <span class="hlt">Cloud</span> Radar (HCR) and the HIAPER Spectral Resolution Lidar (HSRL), among other instrumentation. Aircraft observations were complemented by a suite of satellite-derived products. To observe a the evolution of airmasses over the course of two days, upwind regions were sampled on an outbound flight to from Sacramento, CA, to Kona, HI. The sampled airmasses were then tracked using HYSPLIT trajectories based on GFS model forecasts, and the return flight to California was planned to intercept those airmasses, using satellite observation to track <span class="hlt">cloud</span> evolution in the interim. This approach required that trajectories were reasonably stable up to 3 days prior to final sampling, and also that forecast trajectories were in agreement with post-flight analysis and visual <span class="hlt">cloud</span> feature tracking. The extent to which this was realised, and hence the validity of this new approach to Lagrangian airmass observation, is assessed here. We also present results showing that a Sc-Cu airmass transition was consistently observed during the CSET study using measurements from research flights and satellite.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_17 --> <div id="page_18" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="341"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19890045056&hterms=rust&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Drust','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19890045056&hterms=rust&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Drust"><span>Electrical structure in two thunderstorm anvil <span class="hlt">clouds</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Marshall, Thomas C.; Rust, W. David; Winn, William P.; Gilbert, Kenneth E.</p> <p>1989-01-01</p> <p>Electrical structures in two thunderstorm anvil <span class="hlt">clouds</span> (or 'anvils'), one in New Mexico, the other in Oklahoma, were investigated, using measurements of electric field by balloon-carried instruments and a one-dimensional model to calculate the time and spatial variations of electrical parameters in the clear air below the anvil. The electric field soundings through the two thunderstorm anvils showed similar charge structures; namely, negatively charged screening <span class="hlt">layers</span> on the top and the bottom surfaces, a <span class="hlt">layer</span> of positive charge in the interior, and one or two <span class="hlt">layers</span> of zero charge. It is suggested that the positive charge originated in the main positive charge region normally found at high altitudes in the core of thunderclouds, and the negatively charged <span class="hlt">layers</span> probably formed as screening <span class="hlt">layers</span>, resulting from the discontinuity in the electrical conductivity at the <span class="hlt">cloud</span> boundaries.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.6530R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.6530R"><span>multi-dimensional <span class="hlt">Cloud</span>-aERosol Exploratory Study using RPAS (mCERES): Bottom-up and top-down closure of aerosol-<span class="hlt">cloud</span> interactions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Roberts, Greg; Calmer, Radiance; Sanchez, Kevin; Cayez, Grégoire; Nicoll, Kerianne; Hashimshoni, Eyal; Rosenfeld, Daniel; Ansmann, Albert; Sciare, Jean; Ovadneite, Jurgita; Bronz, Murat; Hattenberger, Gautier; Preissler, Jana; Buehl, Johannes; Ceburnis, Darius; O'Dowd, Colin</p> <p>2016-04-01</p> <p><span class="hlt">Clouds</span> are omnipresent in earth's atmosphere and constitute an important role in regulating the radiative budget of the planet. However, the response of <span class="hlt">clouds</span> to climate change remains uncertain, in particular, with respect to aerosol-<span class="hlt">cloud</span> interactions and feedback mechanisms between the biosphere and atmosphere. Aerosol-<span class="hlt">cloud</span> interactions and their feedbacks are the main themes of the European project FP7 BACCHUS (Impact of Biogenic versus Anthropogenic Emissions on <span class="hlt">Clouds</span> and Climate: towards a Holistic Understanding). The National Center for Meteorological Research (CNRM-GAME, Toulouse, France) conducted airborne experiments in Cyprus and Ireland in March and August 2015 respectively to link ground-based and satellite observations. Multiple RPAS (remotely piloted aircraft systems) were instrumented for a specific scientific focus to characterize the vertical distribution of aerosol, <span class="hlt">cloud</span> microphysical properties, radiative fluxes, 3D wind vectors and meteorological state parameters. Flights below and within <span class="hlt">clouds</span> were coordinated with satellite overpasses to perform 'top-down' closure of <span class="hlt">cloud</span> micro-physical properties. Measurements of <span class="hlt">cloud</span> condensation nuclei spectra at the ground-based site have been used to determine <span class="hlt">cloud</span> microphyical properties using wind vectors and meteorological parameters measured by the RPAS at <span class="hlt">cloud</span> base. These derived <span class="hlt">cloud</span> properties have been validated by in-situ RPAS measurements in the <span class="hlt">cloud</span> and compared to those derived by the Suomi-NPP satellite. In addition, RPAS profiles in Cyprus observed the <span class="hlt">layers</span> of dust originating from the Arabian Peninsula and the Sahara Desert. These profiles generally show a well-mixed boundary <span class="hlt">layer</span> and compare well with ground-based LIDAR observations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003DPS....35.4803G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003DPS....35.4803G"><span>Wave-<span class="hlt">clouds</span> coupling in the Jovian troposphere.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gaulme, P.; Mosser, B.</p> <p>2003-05-01</p> <p>First studies about Jovian oscillations are due to Vorontsov et al. (1976). Attempts to observe them started in the late 1980's (Deming et al. 1989, Mosser et al. 1991). The micro-satellite Jovis and ground-based observations campaign such as SŸMPA (e.g Baglin et al. 1999) account for an accurate analysis of the <span class="hlt">cloud</span> response to an acoustic wave. Therefore, the propagation of sound or gravity waves in the Jovian troposphere is revisited, in order to estimate their effect on the highest <span class="hlt">clouds</span> <span class="hlt">layer</span>. From basic thermodynamics, the troposphere should be stratified in three major ice <span class="hlt">clouds</span> <span class="hlt">layers</span>: water-ammonia, ammonium-hydrosulfide and ammonia ice for the highest. The presence of ammonia ice <span class="hlt">clouds</span> has been inferred from Kuiper in 1952, and was predicted to dominate the Jovian skies. However, they had been observed spectroscopically over less than one percent of the surface. This absence of spectral proof could come from a coating of ammonia particles from other substances (Baines et al. 2002). In this work, we study the behaviour of a <span class="hlt">cloud</span> submitted to a periodic pressure perturbation. We suppose a vertical wave propagating in a plane parallel atmosphere including an ammonia ice <span class="hlt">cloud</span> <span class="hlt">layer</span>. We determine the relation between the Lagrangian pressure perturbation and the variation of the fraction of solid ammonia. The linearized equations governing the evolution of the Eulerian pressure and density perturbed terms allows us to study how the propagation is altered by the <span class="hlt">clouds</span> and how the <span class="hlt">clouds</span> move with the wave. Finally, because a pressure perturbation modifies the fraction of solid ammonia, we estimate how much an ammonia crystal should grow or decrease and how the <span class="hlt">clouds</span> albedo could change with the wave. Baglin et al. 1999. BAAS 31, 813. Baines et al. 2002. Icarus 159, 74. Deming et al. 1989. Icarus 21, 943. Kuiper 1952.The atmospheres of the Earth and Planets pp. 306-405. Univ. of Chicago Press, Chicago. Mosser et al. 1991. A&A 251, 356. Vorontsov et al</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19940020427&hterms=layers+atmosphere&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dlayers%2Batmosphere','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19940020427&hterms=layers+atmosphere&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dlayers%2Batmosphere"><span>Two-dimensional modeling of thermal inversion <span class="hlt">layers</span> in the <span class="hlt">middle</span> atmosphere of Mars</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Theodore, B.; Chassefiere, E.</p> <p>1993-01-01</p> <p>There is some evidence that the thermal structure of the martian <span class="hlt">middle</span> atmosphere may be altered in a significant way by the general circulation motions. Indeed, while it is well known that the circulation in the meridional plane is responsible for the reversal of the latitudinal thermal gradient at the solstice through the adiabatic heating due to sinking motions above the winter pole, here we want to emphasize that a likely by-product effect could be the formation of warm <span class="hlt">layers</span>, mainly located in the winter hemisphere, and exhibiting an inversion of the vertical thermal gradient.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JPhCS.664b2015D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JPhCS.664b2015D"><span>Identity federation in OpenStack - an introduction to hybrid <span class="hlt">clouds</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Denis, Marek; Castro Leon, Jose; Ormancey, Emmanuel; Tedesco, Paolo</p> <p>2015-12-01</p> <p>We are evaluating <span class="hlt">cloud</span> identity federation available in the OpenStack ecosystem that allows for on premise bursting into remote <span class="hlt">clouds</span> with use of local identities (i.e. domain accounts). Further enhancements to identity federation are a clear way to hybrid <span class="hlt">cloud</span> architectures - virtualized infrastructures <span class="hlt">layered</span> across independent private and public <span class="hlt">clouds</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.A41G0046L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.A41G0046L"><span>Magic - Marine Arm Gpci Investigation of <span class="hlt">Clouds</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lewis, E. R.; Wiscombe, W. J.; Albrecht, B. A.; Bland, G.; Flagg, C. N.; Klein, S. A.; Kollias, P.; Mace, G. G.; Reynolds, M.; Schwartz, S. E.; Siebesma, P.; Teixeira, J.; Wood, R.; Zhang, M.</p> <p>2012-12-01</p> <p>MAGIC, the Marine ARM (Atmospheric Radiation Measurement program) GPCI Investigation of <span class="hlt">Clouds</span>, will deploy the Second ARM Mobile Facility (AMF2) aboard the Horizon Lines cargo container ship M/V Spirit traversing the route between Los Angeles, CA and Honolulu, HI from October, 2012 through September, 2013 (except from a few months in the <span class="hlt">middle</span> of this time period when the ship will be in dry dock). During this time AMF2 will observe and characterize the properties of <span class="hlt">clouds</span> and precipitation, aerosols, and atmospheric radiation; standard meteorological and oceanographic variables; and atmospheric structure. There will also be Intensive Observational Periods (IOPs), one in January, 2013 and one in July, 2013 during which more detailed measurements of the atmospheric structure will be made. <span class="hlt">Clouds</span> remain a major source of uncertainty in climate projections. In this context, subtropical marine boundary <span class="hlt">layer</span> (MBL) <span class="hlt">clouds</span> play a key role in <span class="hlt">cloud</span>-climate feedbacks that are not well understood yet play a large role in biases both in seasonal coupled model forecasts and annual mean climate forecasts. In particular, current climate models do not accurately represent the transition from the stratocumulus (Sc) regime, with its high albedo and large impact on the global radiative balance of Earth, to shallow trade-wind cumulus (Cu), which play a fundamental role in global surface evaporation and also albedo. Climate models do not yet adequately parameterize the small-scale physical processes associated with turbulence, convection, and radiation in these <span class="hlt">clouds</span>. Part of this inability results from lack of accurate data on these <span class="hlt">clouds</span> and the conditions responsible for their properties, including aerosol properties, radiation, and atmospheric and oceanographic conditions. The primary objectives of MAGIC are to improve the representation of the Sc-to-Cu transition in climate models by characterizing the essential properties of this transition, and to produce the observed</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/1166848-process-model-simulations-cloud-albedo-enhancement-aerosols-arctic','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/1166848-process-model-simulations-cloud-albedo-enhancement-aerosols-arctic"><span>Process-model Simulations of <span class="hlt">Cloud</span> Albedo Enhancement by Aerosols in the Arctic</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kravitz, Benjamin S.; Wang, Hailong; Rasch, Philip J.</p> <p>2014-11-17</p> <p>A <span class="hlt">cloud</span>-resolving model is used to simulate the effectiveness of Arctic marine <span class="hlt">cloud</span> brightening via injection of <span class="hlt">cloud</span> condensation nuclei (CCN). An updated <span class="hlt">cloud</span> microphysical scheme is employed, with prognostic CCN and <span class="hlt">cloud</span> particle numbers in both liquid and mixed-phase marine low <span class="hlt">clouds</span>. Injection of CCN into the marine boundary <span class="hlt">layer</span> can delay the collapse of the boundary <span class="hlt">layer</span> and increase low-<span class="hlt">cloud</span> albedo. Because nearly all of the albedo effects are in the liquid phase due to the removal of ice water by snowfall when ice processes are involved, albedo increases are stronger for pure liquid <span class="hlt">clouds</span> than mixed-phase <span class="hlt">clouds</span>.more » Liquid precipitation can be suppressed by CCN injection, whereas ice precipitation (snow) is affected less; thus the effectiveness of brightening mixed-phase <span class="hlt">clouds</span> is lower than for liquid-only <span class="hlt">clouds</span>. CCN injection into a clean regime results in a greater albedo increase than injection into a polluted regime, consistent with current knowledge about aerosol-<span class="hlt">cloud</span> interactions. Unlike previous studies investigating warm <span class="hlt">clouds</span>, dynamical changes in circulation due to precipitation changes are small.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26438280','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26438280"><span>Insights into low-latitude <span class="hlt">cloud</span> feedbacks from high-resolution models.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bretherton, Christopher S</p> <p>2015-11-13</p> <p><span class="hlt">Cloud</span> feedbacks are a leading source of uncertainty in the climate sensitivity simulated by global climate models (GCMs). Low-latitude boundary-<span class="hlt">layer</span> and cumulus <span class="hlt">cloud</span> regimes are particularly problematic, because they are sustained by tight interactions between <span class="hlt">clouds</span> and unresolved turbulent circulations. Turbulence-resolving models better simulate such <span class="hlt">cloud</span> regimes and support the GCM consensus that they contribute to positive global <span class="hlt">cloud</span> feedbacks. Large-eddy simulations using sub-100 m grid spacings over small computational domains elucidate marine boundary-<span class="hlt">layer</span> <span class="hlt">cloud</span> response to greenhouse warming. Four observationally supported mechanisms contribute: 'thermodynamic' cloudiness reduction from warming of the atmosphere-ocean column, 'radiative' cloudiness reduction from CO2- and H2O-induced increase in atmospheric emissivity aloft, 'stability-induced' <span class="hlt">cloud</span> increase from increased lower tropospheric stratification, and 'dynamical' cloudiness increase from reduced subsidence. The cloudiness reduction mechanisms typically dominate, giving positive shortwave <span class="hlt">cloud</span> feedback. <span class="hlt">Cloud</span>-resolving models with horizontal grid spacings of a few kilometres illuminate how cumulonimbus <span class="hlt">cloud</span> systems affect climate feedbacks. Limited-area simulations and superparameterized GCMs show upward shift and slight reduction of <span class="hlt">cloud</span> cover in a warmer climate, implying positive <span class="hlt">cloud</span> feedbacks. A global <span class="hlt">cloud</span>-resolving model suggests tropical cirrus increases in a warmer climate, producing positive longwave <span class="hlt">cloud</span> feedback, but results are sensitive to subgrid turbulence and ice microphysics schemes. © 2015 The Author(s).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5144091','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5144091"><span>Aerosol effect on the evolution of the thermodynamic properties of warm convective <span class="hlt">cloud</span> fields</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Dagan, Guy; Koren, Ilan; Altaratz, Orit; Heiblum, Reuven H.</p> <p>2016-01-01</p> <p>Convective <span class="hlt">cloud</span> formation and evolution strongly depend on environmental temperature and humidity profiles. The forming <span class="hlt">clouds</span> 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 <span class="hlt">clouds</span> act to warm the lower part of the cloudy <span class="hlt">layer</span> (where there is net condensation) and cool and moisten the upper part of the cloudy <span class="hlt">layer</span> (where there is net evaporation), thereby destabilizing the <span class="hlt">layer</span>. Under clean conditions, precipitation causes net warming of the cloudy <span class="hlt">layer</span> and net cooling of the sub-<span class="hlt">cloud</span> <span class="hlt">layer</span> (driven by rain evaporation), which together act to stabilize the atmosphere with time. Previous studies have examined different aspects of the effects of <span class="hlt">clouds</span> 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 <span class="hlt">clouds</span>, 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</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27929097','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27929097"><span>Aerosol effect on the evolution of the thermodynamic properties of warm convective <span class="hlt">cloud</span> fields.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Dagan, Guy; Koren, Ilan; Altaratz, Orit; Heiblum, Reuven H</p> <p>2016-12-08</p> <p>Convective <span class="hlt">cloud</span> formation and evolution strongly depend on environmental temperature and humidity profiles. The forming <span class="hlt">clouds</span> 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 <span class="hlt">clouds</span> act to warm the lower part of the cloudy <span class="hlt">layer</span> (where there is net condensation) and cool and moisten the upper part of the cloudy <span class="hlt">layer</span> (where there is net evaporation), thereby destabilizing the <span class="hlt">layer</span>. Under clean conditions, precipitation causes net warming of the cloudy <span class="hlt">layer</span> and net cooling of the sub-<span class="hlt">cloud</span> <span class="hlt">layer</span> (driven by rain evaporation), which together act to stabilize the atmosphere with time. Previous studies have examined different aspects of the effects of <span class="hlt">clouds</span> 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 <span class="hlt">clouds</span>, showing the temporal evolution of the effects. We propose a direct measure for the magnitude and sign of the aerosol effect on thermodynamic instability.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19930006312','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930006312"><span><span class="hlt">Cloud</span> fraction, <span class="hlt">layer</span>, and direction of movement results from sky cameras during the FIRE IFO, Coffeyville, Kansas, experiment for the period Nov. 12 through Dec. 9, 1991</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Purgold, Gerald C.; Wheeler, Robert J.; Whitlock, Charles H.</p> <p>1992-01-01</p> <p>Tables and figures are presented which show local site observations of <span class="hlt">cloud</span> fractions, the number of <span class="hlt">cloud</span> <span class="hlt">layers</span>, direction of movement, and precipitation data collected during the FIRE (First ISCCP Regional Experiment) Phase 2 Cirrus Intensive Field Observations (IFO) conducted in Coffeyville, Kansas during November and December, 1991. Selected data are also presented at the times of the TIROS Operational Vertical Sounder (TOVS) satellite overpass. Several major scientific projects have used surface-based observations of <span class="hlt">clouds</span> to compare directly with those being observed from satellites. Characterizing the physical properties of <span class="hlt">clouds</span> is extremely useful in obtaining a more accurate analysis of the effect of <span class="hlt">clouds</span> and their movements on weather and climate. It is the purpose of this paper to report data collected during the FIRE Phase 2 IFO experiment and to provide a brief history of such a surface-based system and the technical information required for recording local <span class="hlt">cloud</span> parameters.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013PhDT.......406B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013PhDT.......406B"><span>Environmental Controls on Stratocumulus <span class="hlt">Cloud</span> Fraction</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Burleyson, Casey Dale</p> <p></p> <p>Marine stratocumulus <span class="hlt">clouds</span> are widespread, low, optically thick, and persist for long periods of time. Their high albedo allows stratocumulus <span class="hlt">clouds</span> to reflect large amounts of incoming shortwave radiation. Understanding the processes that lead to changes in stratocumulus <span class="hlt">cloud</span> fraction is critically important in capturing the effects of stratocumulus in global climate models (GCMs). This research presents two analyses which seek to better understand the governing processes that drive variability in the stratocumulus-topped boundary <span class="hlt">layer</span> system. The diurnal cycle of marine stratocumulus in <span class="hlt">cloud</span>-topped boundary <span class="hlt">layers</span> is examined using ship-based meteorological data obtained during the 2008 VAMOS Ocean-<span class="hlt">Cloud</span>-Atmosphere-Land Study Regional Experiment (VOCALS-REx). The high temporal and spatial continuity of the ship data, as well as the 31-day sample size, allows us to resolve the diurnal transition in degree of coupling of the stratocumulus-topped boundary <span class="hlt">layer</span>. The amplitude of diurnal variation was comparable to the magnitude of longitudinal differences between regions east and west of 80°W for most of the <span class="hlt">cloud</span>, surface, and precipitation variables examined. The diurnal cycle of precipitation is examined in terms of areal coverage, number of drizzle cells, and estimated rain rate. East of 80°W, the drizzle cell frequency and drizzle area peaks just prior to sunrise. West of 80°W, total drizzle area peaks at 3:00 am, 2-3 hours before sunrise. Peak drizzle cell frequency is three times higher west of 80°W compared to east of 80°W. The waning of drizzle several hours prior to the ramp up of shortwave fluxes may be related to the higher peak drizzle frequencies in the west. The ensemble effect of localized subcloud evaporation of precipitation may make drizzle a self-limiting process where the areal density of drizzle cells is sufficiently high. The daytime reduction in vertical velocity variance in a less coupled boundary <span class="hlt">layer</span> is accompanied by enhanced</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.A11I1999G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.A11I1999G"><span>Satellite Data Analysis of Impact of Anthropogenic Air Pollution on Ice <span class="hlt">Clouds</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gu, Y.; Liou, K. N.; Zhao, B.; Jiang, J. H.; Su, H.</p> <p>2017-12-01</p> <p>Despite numerous studies about the impact of aerosols on ice <span class="hlt">clouds</span>, the role of anthropogenic aerosols in ice processes, especially over pollution regions, remains unclear and controversial, and has not been considered in a regional model. The objective of this study is to improve our understanding of the ice process associated with anthropogenic aerosols, and provide a comprehensive assessment of the contribution of anthropogenic aerosols to ice nucleation, ice <span class="hlt">cloud</span> properties, and the consequent regional radiative forcing. As the first attempt, we evaluate the effects of different aerosol types (mineral dust, air pollution, polluted dust, and smoke) on ice <span class="hlt">cloud</span> micro- and macro-physical properties using satellite data. We identify cases with collocated <span class="hlt">Cloud</span>Sat, CALIPSO, and Aqua observations of vertically resolved aerosol and <span class="hlt">cloud</span> properties, and process these observations into the same spatial resolution. The CALIPSO's aerosol classification algorithm determines aerosol <span class="hlt">layers</span> as one of six defined aerosol types by taking into account the lidar depolarization ratio, integrated attenuated backscattering, surface type, and <span class="hlt">layer</span> elevation. We categorize the cases identified above according to aerosol types, collect relevant aerosol and ice <span class="hlt">cloud</span> variables, and determine the correlation between column/<span class="hlt">layer</span> AOD and ice <span class="hlt">cloud</span> properties for each aerosol type. Specifically, we investigate the correlation between aerosol loading (indicated by the column AOD and <span class="hlt">layer</span> AOD) and ice <span class="hlt">cloud</span> microphysical properties (ice water content, ice crystal number concentration, and ice crystal effective radius) and macro-physical properties (ice water path, ice <span class="hlt">cloud</span> fraction, <span class="hlt">cloud</span> top temperature, and <span class="hlt">cloud</span> thickness). By comparing the responses of ice <span class="hlt">cloud</span> properties to aerosol loadings for different aerosol types, we infer the role of different aerosol types in ice nucleation and the evolution of ice <span class="hlt">clouds</span>. Our preliminary study shows that changes in the ice crystal</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1911436S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1911436S"><span>Recent Findings Related to Giant <span class="hlt">Cloud</span> Condensation Nuclei in the Marine Boundary <span class="hlt">Layer</span> and Impacts on <span class="hlt">Clouds</span> and Precipitation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sorooshian, Armin; Dadashazar, Hossein; Wang, Zhen; Crosbie, Ewan; Brunke, Michael; Zeng, Xubin; Jonsson, Haflidi; Woods, Roy; Flagan, Richard; Seinfeld, John</p> <p>2017-04-01</p> <p>This presentation reports on findings from multiple airborne field campaigns off the California coast to understand the sources, nature, and impacts of giant <span class="hlt">cloud</span> condensation nuclei (GCCN). Aside from sea spray emissions, measurements have revealed that ocean-going ships can be a source of GCCN due to wake and stack emissions off the California coast. Observed particle number concentrations behind 10 ships exceeded those in "control" areas, exhibiting number concentration enhancement ratios (ERs) for minimum threshold diameters of 2, 10, and 20 μm as high as 2.7, 5.5, and 7.5, respectively. The data provide insights into how ER is related to a variety of factors (downwind distance, altitude, ship characteristics such as gross tonnage, length, and beam). The data also provide insight into the extent to which a size distribution parameter and a <span class="hlt">cloud</span> water chemical measurement can capture the effect of sea salt on marine stratocumulus <span class="hlt">cloud</span> properties. The two GCCN proxy variables, near-surface particle number concentration for diameter > 5 µm and <span class="hlt">cloud</span> water chloride concentration, are significantly correlated with each other, and both exhibit expected relationships with other parameters that typically coincide with sea salt emissions. Factors influencing the relationship between these two GCCN proxy measurements will be discussed. When comparing twelve pairs of high and low chloride <span class="hlt">cloud</span> cases (at fixed liquid water path and <span class="hlt">cloud</span> drop number concentration), the average drop spectra for high chloride cases exhibit enhanced drop number at diameters exceeding 20 µm, especially above 30 µm. In addition, high chloride cases coincide with enhanced mean columnar R and negative values of precipitation susceptibility. The difference in drop effective radius (re) between high and low chloride conditions decreases with height in <span class="hlt">cloud</span>, suggesting that some GCCN-produced rain drops precipitate before reaching <span class="hlt">cloud</span> tops. The sign of <span class="hlt">cloud</span> responses (i.e., re, R) to</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009JGRD..11412203S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009JGRD..11412203S"><span>Processes that generate and deplete liquid water and snow in thin midlevel mixed-phase <span class="hlt">clouds</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Smith, Adam J.; Larson, Vincent E.; Niu, Jianguo; Kankiewicz, J. Adam; Carey, Lawrence D.</p> <p>2009-06-01</p> <p>This paper uses a numerical model to investigate microphysical, radiative, and dynamical processes in mixed-phase altostratocumulus <span class="hlt">clouds</span>. Three <span class="hlt">cloud</span> cases are chosen for study, each of which was observed by aircraft during the fifth or ninth Complex <span class="hlt">Layered</span> <span class="hlt">Cloud</span> Experiment (CLEX). These three <span class="hlt">clouds</span> are numerically modeled using large-eddy simulation (LES). The observed and modeled <span class="hlt">clouds</span> consist of a mixed-phase <span class="hlt">layer</span> with a quasi-adiabatic profile of liquid, and a virga <span class="hlt">layer</span> below that consists of snow. A budget of <span class="hlt">cloud</span> (liquid) water mixing ratio is constructed from the simulations. It shows that large-scale ascent/descent, radiative cooling/heating, turbulent transport, and microphysical processes are all significant. Liquid is depleted indirectly via depositional growth of snow (the Bergeron-Findeisen process). This process is more influential than depletion of liquid via accretional growth of snow. Also constructed is a budget of snow mixing ratio, which turns out to be somewhat simpler. It shows that snow grows by deposition in and below the liquid (mixed-phase) <span class="hlt">layer</span>, and sublimates in the remainder of the virga region below. The deposition and sublimation are balanced primarily by sedimentation, which transports the snow from the growth region to the sublimation region below. In our three <span class="hlt">clouds</span>, the vertical extent of the virga <span class="hlt">layer</span> is influenced more by the profile of saturation ratio below the liquid (mixed-phase) <span class="hlt">layer</span> than by the mixing ratio of snow at the top of the virga <span class="hlt">layer</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1995JAtS...52.4159G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1995JAtS...52.4159G"><span>Dynamical Structure and Turbulence in Cirrus <span class="hlt">Clouds</span>: Aircraft Observations during FIRE.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gultepe, I.; Starr, D. O'c.</p> <p>1995-12-01</p> <p>Aircraft data collected during the First International Satellite <span class="hlt">Cloud</span> Climatology Project Regional Experiment (FIRE)I are used to examine dynamical processes operating in cirrus <span class="hlt">cloud</span> systems observed on 19 and 28 October 1986. Measurements from Lagrangian spiral soundings and constant-altitude flight legs are analyzed. Comparisons are made with observations in clear air. Each cirrus case contained a statically stable <span class="hlt">layer</span>, a conditionally unstable or neutrally stratified <span class="hlt">layer</span> (ice pseudoadiabatic) in which convection was prevalent, and a neutral <span class="hlt">layer</span> in which convection was intermittent. The analysis indicates that a mixture of phenomena occurred including small-scale convective cells, gravity waves (2-9 km), quasi-two-dimensional waves (10-20 km), and larger two-dimensional mesoscale waves (100 km). The intermediate-scale waves, observed both in clear air and in the <span class="hlt">cloud</span> systems, likely played an important role in the development of the <span class="hlt">cloud</span> systems given the magnitude of the associated vertical air velocity. The spectra of perturbations of wind components for <span class="hlt">layers</span> where convection was prevalent were characterized by a 5/3 power law dependence, while a 2/4 dependence was found at other levels in the <span class="hlt">cloud</span> systems. A steeper spectral slope (3) was found in the more stable <span class="hlt">cloud</span>-base <span class="hlt">layer</span> on 19 October. Samples in clear air also showed a (2.4) dependence. Flight-leg-averaged eddy potential heat fluxes (H=±8 W m2) were comparable to observations in marine stratocumulus <span class="hlt">clouds</span>. Calculated turbulence dissipation rates agree with previously published studies, which indicate a general enhancement within <span class="hlt">cloud</span> systems (106 to 103 m2 s<IMG border="0" src="/charent/ISO_CHARACTERS_MIXED/LOWERCASE/minus.gif">3 in <span class="hlt">cloud</span> versus values less than 0.5×10<IMG border="0" src="/charent/ISO_CHARACTERS_MIXED/LOWERCASE/minus.gif">6 m2 s<IMG border="0" src="/charent/ISO_CHARACTERS_MIXED/LOWERCASE/minus.gif">3 in clear air).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1281698-simulations-arctic-mixed-phase-clouds-forecasts-cam3-am2-pace','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1281698-simulations-arctic-mixed-phase-clouds-forecasts-cam3-am2-pace"><span>Simulations of arctic mixed-phase <span class="hlt">clouds</span> in forecasts with CAM3 and AM2 for M-PACE</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Xie, Shaocheng; Boyle, James; Klein, Stephen A.; ...</p> <p>2008-02-27</p> <p>[1] Simulations of mixed-phase <span class="hlt">clouds</span> in forecasts with the NCAR Atmosphere Model version 3 (CAM3) and the GFDL Atmospheric Model version 2 (AM2) for the Mixed-Phase Arctic <span class="hlt">Cloud</span> Experiment (M-PACE) are performed using analysis data from numerical weather prediction centers. CAM3 significantly underestimates the observed boundary <span class="hlt">layer</span> mixed-phase <span class="hlt">cloud</span> fraction and cannot realistically simulate the variations of liquid water fraction with temperature and <span class="hlt">cloud</span> height due to its oversimplified <span class="hlt">cloud</span> microphysical scheme. In contrast, AM2 reasonably reproduces the observed boundary <span class="hlt">layer</span> <span class="hlt">cloud</span> fraction while its <span class="hlt">clouds</span> contain much less <span class="hlt">cloud</span> condensate than CAM3 and the observations. The simulation of themore » boundary <span class="hlt">layer</span> mixed-phase <span class="hlt">clouds</span> and their microphysical properties is considerably improved in CAM3 when a new physically based <span class="hlt">cloud</span> microphysical scheme is used (CAM3LIU). The new scheme also leads to an improved simulation of the surface and top of the atmosphere longwave radiative fluxes. Sensitivity tests show that these results are not sensitive to the analysis data used for model initialization. Increasing model horizontal resolution helps capture the subgrid-scale features in Arctic frontal <span class="hlt">clouds</span> but does not help improve the simulation of the single-<span class="hlt">layer</span> boundary <span class="hlt">layer</span> <span class="hlt">clouds</span>. AM2 simulated <span class="hlt">cloud</span> fraction and LWP are sensitive to the change in <span class="hlt">cloud</span> ice number concentrations used in the Wegener-Bergeron-Findeisen process while CAM3LIU only shows moderate sensitivity in its <span class="hlt">cloud</span> fields to this change. Furthermore, this paper shows that the Wegener-Bergeron-Findeisen process is important for these models to correctly simulate the observed features of mixed-phase <span class="hlt">clouds</span>.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008JGRD..113.4211X','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008JGRD..113.4211X"><span>Simulations of Arctic mixed-phase <span class="hlt">clouds</span> in forecasts with CAM3 and AM2 for M-PACE</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Xie, Shaocheng; Boyle, James; Klein, Stephen A.; Liu, Xiaohong; Ghan, Steven</p> <p>2008-02-01</p> <p>Simulations of mixed-phase <span class="hlt">clouds</span> in forecasts with the NCAR Atmosphere Model version 3 (CAM3) and the GFDL Atmospheric Model version 2 (AM2) for the Mixed-Phase Arctic <span class="hlt">Cloud</span> Experiment (M-PACE) are performed using analysis data from numerical weather prediction centers. CAM3 significantly underestimates the observed boundary <span class="hlt">layer</span> mixed-phase <span class="hlt">cloud</span> fraction and cannot realistically simulate the variations of liquid water fraction with temperature and <span class="hlt">cloud</span> height due to its oversimplified <span class="hlt">cloud</span> microphysical scheme. In contrast, AM2 reasonably reproduces the observed boundary <span class="hlt">layer</span> <span class="hlt">cloud</span> fraction while its <span class="hlt">clouds</span> contain much less <span class="hlt">cloud</span> condensate than CAM3 and the observations. The simulation of the boundary <span class="hlt">layer</span> mixed-phase <span class="hlt">clouds</span> and their microphysical properties is considerably improved in CAM3 when a new physically based <span class="hlt">cloud</span> microphysical scheme is used (CAM3LIU). The new scheme also leads to an improved simulation of the surface and top of the atmosphere longwave radiative fluxes. Sensitivity tests show that these results are not sensitive to the analysis data used for model initialization. Increasing model horizontal resolution helps capture the subgrid-scale features in Arctic frontal <span class="hlt">clouds</span> but does not help improve the simulation of the single-<span class="hlt">layer</span> boundary <span class="hlt">layer</span> <span class="hlt">clouds</span>. AM2 simulated <span class="hlt">cloud</span> fraction and LWP are sensitive to the change in <span class="hlt">cloud</span> ice number concentrations used in the Wegener-Bergeron-Findeisen process while CAM3LIU only shows moderate sensitivity in its <span class="hlt">cloud</span> fields to this change. This paper shows that the Wegener-Bergeron-Findeisen process is important for these models to correctly simulate the observed features of mixed-phase <span class="hlt">clouds</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19920003148','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19920003148"><span>Interpreting measurements obtained with the <span class="hlt">cloud</span> absorption radiometer</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1988-01-01</p> <p>The software developed for the analysis of data from the <span class="hlt">Cloud</span> Absorption Radiometer (CAR) is discussed. The CAR is a multichannel radiometer designed to measure the radiation field in the <span class="hlt">middle</span> of an optically thick <span class="hlt">cloud</span> (the diffusion domain). It can also measure the surface albedo and escape function. The instrument currently flies on a C-131A aircraft operated by the University of Washington. Most of this data was collected during the First International satellite <span class="hlt">cloud</span> climatology project Regional Experiment (FIRE) Marine Stratocumulus Intensive Field Observation program off San Diego during July 1987. Earlier flights of the CAR have also been studied.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19950045337&hterms=condensation&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dcondensation','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950045337&hterms=condensation&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dcondensation"><span>Measurements of <span class="hlt">cloud</span> condensation nuclei spectra within maritime cumulus <span class="hlt">cloud</span> droplets: Implications for mixing processes</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Twohy, Cynthia H.; Hudson, James G.</p> <p>1995-01-01</p> <p>In a <span class="hlt">cloud</span> formed during adiabatic expansion, the droplet size distribution will be systematically related to the critical supersaturation of the <span class="hlt">cloud</span> condensation nuclei (CNN), but this relationship can be complicated in entraining <span class="hlt">clouds</span>. Useful information about <span class="hlt">cloud</span> processes, such as mixing, can be obtained from direct measurements of the CNN involved in droplet nucleation. This was accomplished by interfacing two instruments for a series of flights in maritime cumulus <span class="hlt">clouds</span>. One instrument, the counterflow virtual impactor, collected <span class="hlt">cloud</span> droplets, and the nonvolatile residual nuclei of the droplets was then passed to a CCN spectrometer, which measured the critical supersaturation (S(sub c)) spectrum of the droplet nuclei. The measured S(sub c) spectra of the droplet nuclei were compared with the S(sub c) spectra of ambient aerosol particles in order to identify which CCN were actually incorporated into droplets and to determine when mixing processes were active at different <span class="hlt">cloud</span> levels. The droplet nuclei nearly always exhibited lower median S(sub c)'s than the ambient aerosol, as expected since droplets nucleate perferentially on particles with lower critical supersaturations. Critical supersaturation spectra from nuclei of droplets near <span class="hlt">cloud</span> base were similar to those predicted for <span class="hlt">cloud</span> regions formed adiabatically, but spectra of droplet nuclei from <span class="hlt">middle</span> <span class="hlt">cloud</span> levels showed some evidence that mixing had occurred. Near <span class="hlt">cloud</span> top, the greatest variation in the spectra of the droplet nuclei was observed, and nuclei with high S(sub c)'s were sometimes present even within relatively large droplets. This suggests that the extent of mixing increases with height in cumulus <span class="hlt">clouds</span> and that inhomogeneous mixing may be important near <span class="hlt">cloud</span> top. These promising initial results suggest improvements to the experimental technique that will permit more quantitative results in future experiments.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_18 --> <div id="page_19" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="361"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA581730','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA581730"><span>An Evaluation of Northern Hemisphere Merged <span class="hlt">Cloud</span> Analyses from the United States Air Force <span class="hlt">Cloud</span> Depiction Forecasting System II</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2013-03-01</p> <p><span class="hlt">layering</span> and typing to provide a vertical stratification of the <span class="hlt">cloud</span>-filled pixels detected in Level 2. Level 3 output is remapped to the standard AFWA...analyses are compared to one another to see if the most recent analysis also has the lowest estimated error. Optimum interpolation (OI) occurs when...NORTHERN HEMISPHERE MERGED <span class="hlt">CLOUD</span> ANALYSES FROM THE UNITED STATES AIR FORCE <span class="hlt">CLOUD</span> DEPICTION FORECASTING SYSTEM II by Chandra M. Pasillas March</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=GL-2002-001440&hterms=How+get+human+cloud&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DHow%2Bget%2Bhuman%2Bcloud%253F','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=GL-2002-001440&hterms=How+get+human+cloud&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DHow%2Bget%2Bhuman%2Bcloud%253F"><span>Invisible Cirrus <span class="hlt">Clouds</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2002-01-01</p> <p>The Moderate-resolution Imaging Spectroradiometer's (MODIS') <span class="hlt">cloud</span> detection capability is so sensitive that it can detect <span class="hlt">clouds</span> that would be indistinguishable to the human eye. This pair of images highlights MODIS' ability to detect what scientists call 'sub-visible cirrus.' The image on top shows the scene using data collected in the visible part of the electromagnetic spectrum-the part our eyes can see. <span class="hlt">Clouds</span> are apparent in the center and lower right of the image, while the rest of the image appears to be relatively clear. However, data collected at 1.38um (lower image) show that a thick <span class="hlt">layer</span> of previously undetected cirrus <span class="hlt">clouds</span> obscures the entire scene. These kinds of cirrus are called 'sub-visible' because they can't be detected using only visible light. MODIS' 1.38um channel detects electromagnetic radiation in the infrared region of the spectrum. These images were made from data collected on April 4, 2000. Image courtesy Mark Gray, MODIS Atmosphere Team</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=289145','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=289145"><span>The herpetofauna of the <span class="hlt">cloud</span> forests of Honduras</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p></p> <p>2003-01-01</p> <p>The <span class="hlt">cloud</span> forest amphibians and reptiles constitute the most important herpetofaunal segment in Honduras, due to the prevalence of endemic and Nuclear <span class="hlt">Middle</span> American-restricted species. This segment, however, is subject to severe environmental threats due to the actions of humans. Of the 334 species of amphibians and reptiles currently known from Honduras, 122 are known to be distributed in <span class="hlt">cloud</span> forest habitats. <span class="hlt">Cloud</span> forest habitats are found throughout the mountainous interior of Honduras. They are subject to a Highland Wet climate, which features annual precipitation of >1500 mm and a mean annual temperature of <18°C. <span class="hlt">Cloud</span> forest vegetation falls into two Holdridge formations, the Lower Montane Wet Forest and Lower Montane Moist Forest. The Lower Montane Wet Forest formation generally occurs at elevations in excess of 1500 m, although it may occur as low as 1300+ m at some localities. The Lower Montane Moist Forest formation generally occurs at 1700+ m elevation. Of the 122 <span class="hlt">cloud</span> forest species, 18 are salamanders, 38 are anurans, 27 are lizards, and 39 are snakes. Ninety-eight of these 122 species are distributed in the Lower Montane Wet Forest formation and 45 in the Lower Montane Moist Forest formation. Twenty species are distributed in both formations. The <span class="hlt">cloud</span> forest species are distributed among restricted, widespread, and peripheral distributional categories. The restricted species range as a group in elevation from 1340 to 2700 m, the species that are widespread in at least one of the two <span class="hlt">cloud</span> forest formations range as a group from sea level to 2744 m, and the peripheral species range as a group from sea level to 1980 m. The 122 <span class="hlt">cloud</span> forest species exemplify ten broad distributional patterns ranging from species whose northern and southern range termini are in the United States (or Canada) and South America, respectively, to those species that are endemic to Honduras. The largest segment of the herpetofauna falls into the endemic category, with</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA00222&hterms=How+get+human+cloud&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DHow%2Bget%2Bhuman%2Bcloud%253F','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA00222&hterms=How+get+human+cloud&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DHow%2Bget%2Bhuman%2Bcloud%253F"><span>Venus - Lower-level Nightside <span class="hlt">Clouds</span> As Seen By NIMS</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1990-01-01</p> <p>These images are two versions of a near-infrared map of lower-level <span class="hlt">clouds</span> on the night side of Venus, obtained by the Near Infrared Mapping Spectrometer aboard the Galileo spacecraft as it approached the planet February 10, 1990. Taken from an altitude of about 22,000 miles above the planet, at an infrared wavelength of 2.3 microns (about three times the longest wavelength visible to the human eye) the map shows an area of the turbulent, cloudy <span class="hlt">middle</span> atmosphere some 30-33 miles above the surface, 6-10 miles below the visible cloudtops. With a spatial resolution of about 13 miles, this is the sharpest image ever obtained of the mid-level <span class="hlt">clouds</span> of Venus. The image to the left shows the radiant heat from the lower atmosphere (about 400 degrees Fahrenheit) shining through the sulfuric acid <span class="hlt">clouds</span>, which appear as much as 10 times darker than the bright gaps between <span class="hlt">clouds</span>. This <span class="hlt">cloud</span> <span class="hlt">layer</span> is at about - 30 degrees Fahrenheit, at a pressure about 1/2 Earth's atmospheric pressure. This high-resolution map covers a 40- degree-wide sector of the Northern Hemisphere. The several irregular vertical stripes are data dropouts. The right image, a modified negative, represents what scientists believe would be the visual appearance of this mid-level <span class="hlt">cloud</span> deck in daylight, with the <span class="hlt">clouds</span> reflecting sunlight instead of blocking out infrared from the hot planet and lower atmosphere. Near the equator, the <span class="hlt">clouds</span> appear fluffy and blocky; farther north, they are stretched out into East-West filaments by winds estimated at more than 150 mph, while the poles are capped by thick <span class="hlt">clouds</span> at this altitude. The Near Infrared Mapping Spectrometer (NIMS) on the Galileo spacecraft is a combined mapping (imaging) and spectral instrument. It can sense 408 contiguous wavelengths from 0.7 microns (deep red) to 5.2 microns, and can construct a map or image by mechanical scanning. It can spectroscopically analyze atmospheres and surfaces and construct thermal and chemical maps. Designed and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20090011854&hterms=pyranometer&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dpyranometer','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20090011854&hterms=pyranometer&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dpyranometer"><span>A Climatology of Midlatitude Continental <span class="hlt">Clouds</span> from the ARM SGP Site. Part I; Low-Level <span class="hlt">Cloud</span> Macrophysical, Microphysical, and Radiative Properties</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Dong, Xiquan; Minnis, Patrick; Xi, Baike</p> <p>2005-01-01</p> <p>A record of single-<span class="hlt">layer</span> and overcast low <span class="hlt">cloud</span> (stratus) properties has been generated using approximately 4000 hours of data collected from January 1997 to December 2002 at the Atmospheric Radiation Measurement (ARM) Southern Great Plains Central Facility (SCF). The <span class="hlt">cloud</span> properties include liquid-phase and liquid-dominant, mixed-phase, low <span class="hlt">cloud</span> macrophysical, microphysical, and radiative properties including <span class="hlt">cloud</span>-base and -top heights and temperatures, and <span class="hlt">cloud</span> physical thickness derived from a ground-based radar and lidar pair, and rawinsonde sounding; <span class="hlt">cloud</span> liquid water path (LWP) and content (LWC), and <span class="hlt">cloud</span>-droplet effective radius (r(sub e)) and number concentration (N) derived from the macrophysical properties and radiometer data; and <span class="hlt">cloud</span> optical depth (tau), effective solar transmission (gamma), and <span class="hlt">cloud</span>/top-of-atmosphere albedos (R(sub cldy)/R(sub TOA)) derived from Eppley precision spectral pyranometer measurements. The <span class="hlt">cloud</span> properties were analyzed in terms of their seasonal, monthly, and hourly variations. In general, more stratus <span class="hlt">clouds</span> occur during winter and spring than in summer. <span class="hlt">Cloud-layer</span> altitudes and physical thicknesses were higher and greater in summer than in winter with averaged physical thicknesses of 0.85 km and 0.73 km for day and night, respectively. The seasonal variations of LWP, LWC, N. tau, R(sub cldy), and R(sub TOA) basically follow the same pattern with maxima and minima during winter and summer, respectively. There is no significant variation in mean r(sub e), however, despite a summertime peak in aerosol loading, Although a considerable degree of variability exists, the 6-yr average values of LWP, LWC, r(sub e), N, tau, gamma, R(sub cldy) and R(sub TOA) are 150 gm(exp -2) (138), 0.245 gm(exp -3) (0.268), 8.7 micrometers (8.5), 213 cm(exp -3) (238), 26.8 (24.8), 0.331, 0.672, 0.563 for daytime (nighttime). A new conceptual model of midlatitude continental low <span class="hlt">clouds</span> at the ARM SGP site has been developed from this study</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20040171257','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20040171257"><span>THOR: <span class="hlt">Cloud</span> Thickness from Off beam Lidar Returns</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Cahalan, Robert F.; McGill, Matthew; Kolasinski, John; Varnai, Tamas; Yetzer, Ken</p> <p>2004-01-01</p> <p>Conventional wisdom is that lidar pulses do not significantly penetrate <span class="hlt">clouds</span> having optical thickness exceeding about tau = 2, and that no returns are detectable from more than a shallow skin depth. Yet optically thicker <span class="hlt">clouds</span> of tau much greater than 2 reflect a larger fraction of visible photons, and account for much of Earth s global average albedo. As <span class="hlt">cloud</span> <span class="hlt">layer</span> thickness grows, an increasing fraction of reflected photons are scattered multiple times within the <span class="hlt">cloud</span>, and return from a diffuse concentric halo that grows around the incident pulse, increasing in horizontal area with <span class="hlt">layer</span> physical thickness. The reflected halo is largely undetected by narrow field-of-view (FoV) receivers commonly used in lidar applications. THOR - Thickness from Off-beam Returns - is an airborne wide-angle detection system with multiple FoVs, capable of observing the diffuse halo, detecting wide-angle signal from which physical thickness of optically thick <span class="hlt">clouds</span> can be retrieved. In this paper we describe the THOR system, demonstrate that the halo signal is stronger for thicker <span class="hlt">clouds</span>, and validate physical thickness retrievals for <span class="hlt">clouds</span> having z > 20, from NASA P-3B flights over the Department of Energy/Atmospheric Radiation Measurement/Southern Great Plains site, using the lidar, radar and other ancillary ground-based data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1355939-cloud-circulation-feedbacks-near-global-aquaplanet-cloud-resolving-model','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1355939-cloud-circulation-feedbacks-near-global-aquaplanet-cloud-resolving-model"><span><span class="hlt">Cloud</span> and circulation feedbacks in a near-global aquaplanet <span class="hlt">cloud</span>-resolving model</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Narenpitak, Pornampai; Bretherton, Christopher S.; Khairoutdinov, Marat F.</p> <p>2017-05-08</p> <p>A near-global aquaplanet <span class="hlt">cloud</span>-resolving model (NGAqua) with fixed meridionally varying sea-surface temperature (SST) is used to investigate <span class="hlt">cloud</span> feedbacks due to three climate perturbations: a uniform 4 K SST increase, a quadrupled-CO2 concentration, and both combined. NGAqua has a horizontal resolution of 4 km with no cumulus parameterization. Its domain is a zonally periodic 20,480 km-long tropical channel, spanning 46°S–N. It produces plausible mean distributions of <span class="hlt">clouds</span>, rainfall, and winds. After spin-up, 80 days are analyzed for the control and increased-SST simulations, and 40 days for those with quadrupled CO 2. The Intertropical Convergence Zone width and tropical <span class="hlt">cloud</span> covermore » are not strongly affected by SST warming or CO 2 increase, except for the expected upward shift in high <span class="hlt">clouds</span> with warming, but both perturbations weaken the Hadley circulation. Increased SST induces a statistically significant increase in subtropical low <span class="hlt">cloud</span> fraction and in-<span class="hlt">cloud</span> liquid water content but decreases midlatitude <span class="hlt">cloud</span>, yielding slightly positive domain-mean shortwave <span class="hlt">cloud</span> feedbacks. CO 2 quadrupling causes a slight shallowing and a statistically insignificant reduction of subtropical low <span class="hlt">cloud</span> fraction. Warming-induced low <span class="hlt">cloud</span> changes are strongly correlated with changes in estimated inversion strength, which increases modestly in the subtropics but decreases in the midlatitudes. Enhanced clear-sky boundary <span class="hlt">layer</span> radiative cooling in the warmer climate accompanies the robust subtropical low <span class="hlt">cloud</span> increase. The probability distribution of column relative humidity across the tropics and subtropics is compared between the control and increased-SST simulations. It shows no evidence of bimodality or increased convective aggregation in a warmer climate.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/1355939-cloud-circulation-feedbacks-near-global-aquaplanet-cloud-resolving-model','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/1355939-cloud-circulation-feedbacks-near-global-aquaplanet-cloud-resolving-model"><span><span class="hlt">Cloud</span> and circulation feedbacks in a near-global aquaplanet <span class="hlt">cloud</span>-resolving model</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Narenpitak, Pornampai; Bretherton, Christopher S.; Khairoutdinov, Marat F.</p> <p></p> <p>A near-global aquaplanet <span class="hlt">cloud</span>-resolving model (NGAqua) with fixed meridionally varying sea-surface temperature (SST) is used to investigate <span class="hlt">cloud</span> feedbacks due to three climate perturbations: a uniform 4 K SST increase, a quadrupled-CO2 concentration, and both combined. NGAqua has a horizontal resolution of 4 km with no cumulus parameterization. Its domain is a zonally periodic 20,480 km-long tropical channel, spanning 46°S–N. It produces plausible mean distributions of <span class="hlt">clouds</span>, rainfall, and winds. After spin-up, 80 days are analyzed for the control and increased-SST simulations, and 40 days for those with quadrupled CO 2. The Intertropical Convergence Zone width and tropical <span class="hlt">cloud</span> covermore » are not strongly affected by SST warming or CO 2 increase, except for the expected upward shift in high <span class="hlt">clouds</span> with warming, but both perturbations weaken the Hadley circulation. Increased SST induces a statistically significant increase in subtropical low <span class="hlt">cloud</span> fraction and in-<span class="hlt">cloud</span> liquid water content but decreases midlatitude <span class="hlt">cloud</span>, yielding slightly positive domain-mean shortwave <span class="hlt">cloud</span> feedbacks. CO 2 quadrupling causes a slight shallowing and a statistically insignificant reduction of subtropical low <span class="hlt">cloud</span> fraction. Warming-induced low <span class="hlt">cloud</span> changes are strongly correlated with changes in estimated inversion strength, which increases modestly in the subtropics but decreases in the midlatitudes. Enhanced clear-sky boundary <span class="hlt">layer</span> radiative cooling in the warmer climate accompanies the robust subtropical low <span class="hlt">cloud</span> increase. The probability distribution of column relative humidity across the tropics and subtropics is compared between the control and increased-SST simulations. It shows no evidence of bimodality or increased convective aggregation in a warmer climate.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017SPIE10127E..0IK','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017SPIE10127E..0IK"><span>Sparsity-based fast CGH generation using <span class="hlt">layer</span>-based approach for 3D point <span class="hlt">cloud</span> model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kim, Hak Gu; Jeong, Hyunwook; Ro, Yong Man</p> <p>2017-03-01</p> <p>Computer generated hologram (CGH) is becoming increasingly important for a 3-D display in various applications including virtual reality. In the CGH, holographic fringe patterns are generated by numerically calculating them on computer simulation systems. However, a heavy computational cost is required to calculate the complex amplitude on CGH plane for all points of 3D objects. This paper proposes a new fast CGH generation based on the sparsity of CGH for 3D point <span class="hlt">cloud</span> model. The aim of the proposed method is to significantly reduce computational complexity while maintaining the quality of the holographic fringe patterns. To that end, we present a new <span class="hlt">layer</span>-based approach for calculating the complex amplitude distribution on the CGH plane by using sparse FFT (sFFT). We observe the CGH of a <span class="hlt">layer</span> of 3D objects is sparse so that dominant CGH is rapidly generated from a small set of signals by sFFT. Experimental results have shown that the proposed method is one order of magnitude faster than recently reported fast CGH generation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JAMES...9..616A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JAMES...9..616A"><span>Coupling with ocean mixed <span class="hlt">layer</span> leads to intraseasonal variability in tropical deep convection: Evidence from <span class="hlt">cloud</span>-resolving simulations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Anber, Usama; Wang, Shuguang; Sobel, Adam</p> <p>2017-03-01</p> <p>The effect of coupling a slab ocean mixed <span class="hlt">layer</span> to atmospheric convection is examined in <span class="hlt">cloud</span>-resolving model (CRM) simulations in vertically sheared and unsheared environments without Coriolis force, with the large-scale circulation parameterized using the Weak Temperature Gradient (WTG) approximation. Surface fluxes of heat and moisture as well as radiative fluxes are fully interactive, and the vertical profile of domain-averaged horizontal wind is strongly relaxed toward specified profiles with vertical shear that varies from one simulation to the next. Vertical wind shear is found to play a critical role in the simulated behavior. There exists a threshold value of the shear strength above which the coupled system develops regular oscillations between deep convection and dry nonprecipitating states, similar to those found earlier in a much more idealized model which did not consider wind shear. The threshold value of the vertical shear found here varies with the depth of the ocean mixed <span class="hlt">layer</span>. The time scale of the spontaneously generated oscillations also varies with mixed <span class="hlt">layer</span> depth, from 10 days with a 1 m deep mixed <span class="hlt">layer</span> to 50 days with a 10 m deep mixed <span class="hlt">layer</span>. The results suggest the importance of the interplay between convection organized by vertical wind shear, radiative feedbacks, large-scale dynamics, and ocean mixed <span class="hlt">layer</span> heat storage in real intraseasonal oscillations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007AGUFM.A53D1446B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AGUFM.A53D1446B"><span>Assimilation of GOES-Derived <span class="hlt">Cloud</span> Fields Into MM5</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Biazar, A. P.; Doty, K. G.; McNider, R.</p> <p>2007-12-01</p> <p>This approach for the assimilation of GOES-derived <span class="hlt">cloud</span> data into an atmospheric model (the Fifth-Generation Pennsylvania State University-National Center for Atmospheric Research Mesoscale Model, or MM5) was performed in two steps. In the first step, multiple linear regression equations were developed using a control MM5 simulation to develop relationships for several dependent variables in model columns that had one or more <span class="hlt">layers</span> of <span class="hlt">clouds</span>. In the second step, the regression equations were applied during an MM5 simulation with assimilation in which the hourly GOES satellite data were used to determine the <span class="hlt">cloud</span> locations and some of the <span class="hlt">cloud</span> properties, but with all the other variables being determined by the model data. The satellite-derived fields used were shortwave <span class="hlt">cloud</span> albedo and <span class="hlt">cloud</span> top pressure. Ten multiple linear regression equations were developed for the following dependent variables: total <span class="hlt">cloud</span> depth, number of <span class="hlt">cloud</span> <span class="hlt">layers</span>, depth of the <span class="hlt">layer</span> that contains the maximum vertical velocity, the maximum vertical velocity, the height of the maximum vertical velocity, the estimated 1-h stable (i.e., grid scale) precipitation rate, the estimated 1-h convective precipitation rate, the height of the level with the maximum positive diabatic heating, the magnitude of the maximum positive diabatic heating, and the largest continuous <span class="hlt">layer</span> of upward motion. The horizontal components of the divergent wind were adjusted to be consistent with the regression estimate of the maximum vertical velocity. The new total horizontal wind field with these new divergent components was then used to nudge an ongoing MM5 model simulation towards the target vertical velocity. Other adjustments included diabatic heating and moistening at specified levels. Where the model simulation had <span class="hlt">clouds</span> when the satellite data indicated clear conditions, procedures were taken to remove or diminish the errant <span class="hlt">clouds</span>. The results for the period of 0000 UTC 28 June - 0000 UTC 16 July 1999</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19780009489','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19780009489"><span>Analyses of the <span class="hlt">cloud</span> contents of multispectral imagery from LANDSAT 2: Mesoscale assessments of <span class="hlt">cloud</span> and rainfall over the British Isles</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Barrett, E. C.; Grant, C. K. (Principal Investigator)</p> <p>1977-01-01</p> <p>The author has identified the following significant results. It was demonstrated that satellites with sufficiently high resolution capability in the visible region of the electromagnetic spectrum could be used to check the accuracy of estimates of total <span class="hlt">cloud</span> amount assessed subjectively from the ground, and to reveal areas of performance in which corrections should be made. It was also demonstrated that, in <span class="hlt">middle</span> latitude in summer, <span class="hlt">cloud</span> shadow may obscure at least half as much again of the land surface covered by an individual LANDSAT frame as the <span class="hlt">cloud</span> itself. That proportion would increase with latitude and/or time of year towards the winter solstice. Analyses of sample multispectral images for six different categories of <span class="hlt">clouds</span> in summer revealed marked differences between the reflectance characteristics of <span class="hlt">cloud</span> fields in the visible/near infrared region of the spectrum.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA00448&hterms=formation+day+night&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dformation%2Bday%2Bnight','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA00448&hterms=formation+day+night&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dformation%2Bday%2Bnight"><span>Sahara Dust <span class="hlt">Cloud</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2005-01-01</p> <p><p/> [figure removed for brevity, see original site] Dust Particles Click on the image for Quicktime movie from 7/15-7/24 <p/> A continent-sized <span class="hlt">cloud</span> of hot air and dust originating from the Sahara Desert crossed the Atlantic Ocean and headed towards Florida and the Caribbean. A Saharan Air <span class="hlt">Layer</span>, or SAL, forms when dry air and dust rise from Africa's west coast and ride the trade winds above the Atlantic Ocean. <p/> These dust <span class="hlt">clouds</span> are not uncommon, especially during the months of July and August. They start when weather patterns called tropical waves pick up dust from the desert in North Africa, carry it a couple of miles into the atmosphere and drift westward. <p/> In a sequence of images created by data acquired by the Earth-orbiting Atmospheric Infrared Sounder ranging from July 15 through July 24, we see the distribution of the <span class="hlt">cloud</span> in the atmosphere as it swirls off of Africa and heads across the ocean to the west. Using the unique silicate spectral signatures of dust in the thermal infrared, AIRS can detect the presence of dust in the atmosphere day or night. This detection works best if there are no <span class="hlt">clouds</span> present on top of the dust; when <span class="hlt">clouds</span> are present, they can interfere with the signal, making it much harder to detect dust as in the case of July 24, 2005. <p/> In the Quicktime movie, the scale at the bottom of the images shows +1 for dust definitely detected, and ranges down to -1 for no dust detected. The plots are averaged over a number of AIRS observations falling within grid boxes, and so it is possible to obtain fractional numbers. [figure removed for brevity, see original site] Total Water Vapor in the Atmosphere Around the Dust <span class="hlt">Cloud</span> Click on the image for Quicktime movie <p/> The dust <span class="hlt">cloud</span> is contained within a dry adiabatic <span class="hlt">layer</span> which originates over the Sahara Desert. This Saharan Air <span class="hlt">Layer</span> (SAL) advances Westward over the Atlantic Ocean, overriding the cool, moist air nearer the surface. This burst of very dry air is visible in the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..1512183N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..1512183N"><span>Inhomogeneities in frontal cirrus <span class="hlt">clouds</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Neis, Patrick; Krämer, Martina; Hoor, Peter; Reutter, Philipp; Spichtinger, Peter</p> <p>2013-04-01</p> <p>Frontal cirrus <span class="hlt">clouds</span> have a scientifically proven effect on the Earth's radiation budget and thereby an influence on the weather and climate change in regional scale. The formation processes and structures of frontal cirrus <span class="hlt">clouds</span> are still not fully understood. For a close investigation of typical frontal cirrus <span class="hlt">clouds</span>, we use in situ measurements from the CIRRUS-III campaign over Germany and Northern Europe in November 2006. Besides water vapour, <span class="hlt">cloud</span> ice water content, ice particle size distributions, condensation nuclei, and reactive nitrogen were measured during 6 flights. In this work the data of the 24th November flight is used to detect and to analyze warm frontal cirrus <span class="hlt">clouds</span> in the mid latitudes on small temporal and spatial scale. Further, these results are compared with large-scale meteorological analyses from ECMWF and satellite data. Combining these data, the formation and evolution of inhomogeneities in the cirrus <span class="hlt">cloud</span> structure are investigated. One important result is a qualitative agreement between the occurrence of cirrus <span class="hlt">clouds</span> and the 'sharpness' of the Tropopause Inversion <span class="hlt">Layer</span> (TIL).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23060318','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23060318"><span>Toward ubiquitous healthcare services with a novel efficient <span class="hlt">cloud</span> platform.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>He, Chenguang; Fan, Xiaomao; Li, Ye</p> <p>2013-01-01</p> <p>Ubiquitous healthcare services are becoming more and more popular, especially under the urgent demand of the global aging issue. <span class="hlt">Cloud</span> computing owns the pervasive and on-demand service-oriented natures, which can fit the characteristics of healthcare services very well. However, the abilities in dealing with multimodal, heterogeneous, and nonstationary physiological signals to provide persistent personalized services, meanwhile keeping high concurrent online analysis for public, are challenges to the general <span class="hlt">cloud</span>. In this paper, we proposed a private <span class="hlt">cloud</span> platform architecture which includes six <span class="hlt">layers</span> according to the specific requirements. This platform utilizes message queue as a <span class="hlt">cloud</span> engine, and each <span class="hlt">layer</span> thereby achieves relative independence by this loosely coupled means of communications with publish/subscribe mechanism. Furthermore, a plug-in algorithm framework is also presented, and massive semistructure or unstructured medical data are accessed adaptively by this <span class="hlt">cloud</span> architecture. As the testing results showing, this proposed <span class="hlt">cloud</span> platform, with robust, stable, and efficient features, can satisfy high concurrent requests from ubiquitous healthcare services.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27702889','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27702889"><span>Black carbon solar absorption suppresses turbulence in the atmospheric boundary <span class="hlt">layer</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wilcox, Eric M; Thomas, Rick M; Praveen, Puppala S; Pistone, Kristina; Bender, Frida A-M; Ramanathan, Veerabhadran</p> <p>2016-10-18</p> <p>The introduction of <span class="hlt">cloud</span> condensation nuclei and radiative heating by sunlight-absorbing aerosols can modify the thickness and coverage of low <span class="hlt">clouds</span>, yielding significant radiative forcing of climate. The magnitude and sign of changes in <span class="hlt">cloud</span> coverage and depth in response to changing aerosols are impacted by turbulent dynamics of the cloudy atmosphere, but integrated measurements of aerosol solar absorption and turbulent fluxes have not been reported thus far. Here we report such integrated measurements made from unmanned aerial vehicles (UAVs) during the CARDEX (<span class="hlt">Cloud</span> Aerosol Radiative Forcing and Dynamics Experiment) investigation conducted over the northern Indian Ocean. The UAV and surface data reveal a reduction in turbulent kinetic energy in the surface mixed <span class="hlt">layer</span> at the base of the atmosphere concurrent with an increase in absorbing black carbon aerosols. Polluted conditions coincide with a warmer and shallower surface mixed <span class="hlt">layer</span> because of aerosol radiative heating and reduced turbulence. The polluted surface mixed <span class="hlt">layer</span> was also observed to be more humid with higher relative humidity. Greater humidity enhances <span class="hlt">cloud</span> development, as evidenced by polluted <span class="hlt">clouds</span> that penetrate higher above the top of the surface mixed <span class="hlt">layer</span>. Reduced entrainment of dry air into the surface <span class="hlt">layer</span> from above the inversion capping the surface mixed <span class="hlt">layer</span>, due to weaker turbulence, may contribute to higher relative humidity in the surface <span class="hlt">layer</span> during polluted conditions. Measurements of turbulence are important for studies of aerosol effects on <span class="hlt">clouds</span>. Moreover, reduced turbulence can exacerbate both the human health impacts of high concentrations of fine particles and conditions favorable for low-visibility fog events.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5081626','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5081626"><span>Black carbon solar absorption suppresses turbulence in the atmospheric boundary <span class="hlt">layer</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Wilcox, Eric M.; Thomas, Rick M.; Praveen, Puppala S.; Pistone, Kristina; Bender, Frida A.-M.; Ramanathan, Veerabhadran</p> <p>2016-01-01</p> <p>The introduction of <span class="hlt">cloud</span> condensation nuclei and radiative heating by sunlight-absorbing aerosols can modify the thickness and coverage of low <span class="hlt">clouds</span>, yielding significant radiative forcing of climate. The magnitude and sign of changes in <span class="hlt">cloud</span> coverage and depth in response to changing aerosols are impacted by turbulent dynamics of the cloudy atmosphere, but integrated measurements of aerosol solar absorption and turbulent fluxes have not been reported thus far. Here we report such integrated measurements made from unmanned aerial vehicles (UAVs) during the CARDEX (<span class="hlt">Cloud</span> Aerosol Radiative Forcing and Dynamics Experiment) investigation conducted over the northern Indian Ocean. The UAV and surface data reveal a reduction in turbulent kinetic energy in the surface mixed <span class="hlt">layer</span> at the base of the atmosphere concurrent with an increase in absorbing black carbon aerosols. Polluted conditions coincide with a warmer and shallower surface mixed <span class="hlt">layer</span> because of aerosol radiative heating and reduced turbulence. The polluted surface mixed <span class="hlt">layer</span> was also observed to be more humid with higher relative humidity. Greater humidity enhances <span class="hlt">cloud</span> development, as evidenced by polluted <span class="hlt">clouds</span> that penetrate higher above the top of the surface mixed <span class="hlt">layer</span>. Reduced entrainment of dry air into the surface <span class="hlt">layer</span> from above the inversion capping the surface mixed <span class="hlt">layer</span>, due to weaker turbulence, may contribute to higher relative humidity in the surface <span class="hlt">layer</span> during polluted conditions. Measurements of turbulence are important for studies of aerosol effects on <span class="hlt">clouds</span>. Moreover, reduced turbulence can exacerbate both the human health impacts of high concentrations of fine particles and conditions favorable for low-visibility fog events. PMID:27702889</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AcAau.127..553K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AcAau.127..553K"><span>Test study on the performance of shielding configuration with stuffed <span class="hlt">layer</span> under hypervelocity impact</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ke, Fa-wei; Huang, Jie; Wen, Xue-zhong; Ma, Zhao-xia; Liu, Sen</p> <p>2016-10-01</p> <p>In order to study the cracking and intercepting mechanism of stuffed <span class="hlt">layer</span> configuration on the debris <span class="hlt">cloud</span> and to develop stuffed <span class="hlt">layer</span> configuration with better performance, the hypervelocity impact tests on shielding configurations with stuffed <span class="hlt">layer</span> were carried out. Firstly, the hypervelocity impact tests on the shielding configuration with stuffed <span class="hlt">layer</span> of 3 <span class="hlt">layer</span> ceramic fibre and 3 <span class="hlt">layer</span> aramid fibre were finished, the study results showed that the debris <span class="hlt">cloud</span> generated by the aluminum sphere impacting bumper at the velocity of about 6.2 km/s would be racked and intercepted by the stuffed <span class="hlt">layer</span> configuration efficiently when the ceramic fibre <span class="hlt">layers</span> and aramid fibre <span class="hlt">layers</span> were jointed together, however, the shielding performance would be declined when the ceramic fibre <span class="hlt">layers</span> and aramid fibre <span class="hlt">layers</span> were divided by some distance. The mechanism of stuffed <span class="hlt">layer</span> racking and intercepting the debris <span class="hlt">cloud</span> was analyzed according to the above test results. Secondly, based on the mechanism of the stuffed <span class="hlt">layer</span> cracking and intercepint debirs <span class="hlt">cloud</span> the hypervelocity impact tests on the following three stuffed <span class="hlt">layer</span> structures with the equivalent areal density to the 1 mm-thick aluminum plate were also carried out to compare their performance of cracking and intercepting debris <span class="hlt">cloud</span>. The mechanisms of stuffed <span class="hlt">layer</span> racking and intercepting the debris <span class="hlt">cloud</span> were validated by the test result. Thirdly, the influence of the stuffed <span class="hlt">layer</span> position on the shielding performance was studied by the test, too. The test results would provide reference for the design of better performance shielding configuration with stuffed <span class="hlt">layer</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19880057254&hterms=tethered+balloons&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dtethered%2Bballoons','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19880057254&hterms=tethered+balloons&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dtethered%2Bballoons"><span>Observations of marine stratocumulus <span class="hlt">clouds</span> during FIRE</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Albrecht, Bruce A.; Randall, David A.; Nicholls, Stephen</p> <p>1988-01-01</p> <p>The First International Satellite <span class="hlt">Cloud</span> Climatology Project Regional Experiment (FIRE) to study extensive fields of stratocumulus <span class="hlt">clouds</span> off the coast of California is presented. Measurements on the regional and detailed local scales were taken, allowing for a wide interpretation of the mean, turbulent, microphysical, radiative, and chemical characteristics of stratocumulus. Multiple aircraft and ground-based remote-sensing systems were used to study the time evolution of the boundary <span class="hlt">layer</span> structure over a three-week period, and probes from tethered balloons were used to measure turbulence and to collect <span class="hlt">cloud</span>-microphysical and <span class="hlt">cloud</span>-radiative data. The observations provide a base for studying the generation maintenance and dissipation of stratocumulus <span class="hlt">clouds</span>, and could aid in developing numerical models and improved methods for retrieving <span class="hlt">cloud</span> properties by satellite.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20130005720&hterms=al+gore&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dal%2Bgore','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20130005720&hterms=al+gore&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dal%2Bgore"><span>Examining the Impact of Overlying Aerosols on the Retrieval of <span class="hlt">Cloud</span> Optical Properties from Passive Remote Sensing</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Coddington, O. M.; Pilewskie, P.; Redemann, J.; Platnick, S.; Russell, P. B.; Schmidt, K. S.; Gore, W. J.; Livingston, J.; Wind, G.; Vukicevic, T.</p> <p>2010-01-01</p> <p>Haywood et al. (2004) show that an aerosol <span class="hlt">layer</span> above a <span class="hlt">cloud</span> can cause a bias in the retrieved <span class="hlt">cloud</span> optical thickness and effective radius. Monitoring for this potential bias is difficult because space ]based passive remote sensing cannot unambiguously detect or characterize aerosol above <span class="hlt">cloud</span>. We show that <span class="hlt">cloud</span> retrievals from aircraft measurements above <span class="hlt">cloud</span> and below an overlying aerosol <span class="hlt">layer</span> are a means to test this bias. The data were collected during the Intercontinental Chemical Transport Experiment (INTEX-A) study based out of Portsmouth, New Hampshire, United States, above extensive, marine stratus <span class="hlt">cloud</span> banks affected by industrial outflow. Solar Spectral Flux Radiometer (SSFR) irradiance measurements taken along a lower level flight leg above <span class="hlt">cloud</span> and below aerosol were unaffected by the overlying aerosol. Along upper level flight legs, the irradiance reflected from <span class="hlt">cloud</span> top was transmitted through an aerosol <span class="hlt">layer</span>. We compare SSFR <span class="hlt">cloud</span> retrievals from below ]aerosol legs to satellite retrievals from the Moderate Resolution Imaging Spectroradiometer (MODIS) in order to detect an aerosol ]induced bias. In regions of small variation in <span class="hlt">cloud</span> properties, we find that SSFR and MODIS-retrieved <span class="hlt">cloud</span> optical thickness compares within the uncertainty range for each instrument while SSFR effective radius tend to be smaller than MODIS values (by 1-2 microns) and at the low end of MODIS uncertainty estimates. In regions of large variation in <span class="hlt">cloud</span> properties, differences in SSFR and MODIS ]retrieved <span class="hlt">cloud</span> optical thickness and effective radius can reach values of 10 and 10 microns, respectively. We include aerosols in forward modeling to test the sensitivity of SSFR <span class="hlt">cloud</span> retrievals to overlying aerosol <span class="hlt">layers</span>. We find an overlying absorbing aerosol <span class="hlt">layer</span> biases SSFR <span class="hlt">cloud</span> retrievals to smaller effective radii and optical thickness while nonabsorbing aerosols had no impact.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_19 --> <div id="page_20" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="381"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20080015842','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20080015842"><span>Convective Formation of Pileus <span class="hlt">Cloud</span> Near the Tropopause</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Garrett, Timothy J.; Dean-Day, Jonathan; Liu, Chuntao; Barnett, Brian K.; Mace, Gerald G.; Baumgardner, Darrel G.; Webster, Christopher R.; Bui, T. Paul; Read, William G.; Minnis, Patrick</p> <p>2005-01-01</p> <p>Pileus <span class="hlt">clouds</span> form where humid, stably stratified air is mechanically displaced vertically ahead of rising convection. This paper describes convective formation of pileus <span class="hlt">cloud</span> in the tropopause transition <span class="hlt">layer</span> (TTL), and explores a possible link to the formation of long-lasting cirrus at cold temperatures. In-situ measurements from off the coast of Honduras during the July 2002 CRYSTALFACE experiment show an example of TTL cirrus associated with, and penetrated by, deep convection. The cirrus was enriched with total water compared to its surroundings, but composed of extremely small ice crystals with effective radii between 2 and 4 m. Through gravity wave analysis, and intercomparison of measured and simulated <span class="hlt">cloud</span> microphysics, it is argued that the TTL cirrus in this case originated neither from convectively-forced gravity wave motions nor environmental mixing alone. Rather, it is hypothesized that some combination was involved in which, first, convection forced pileus <span class="hlt">cloud</span> to form from TTL air; second, it punctured the pileus <span class="hlt">layer</span>, contributing larger ice crystals through interfacial mixing; third, the addition of condensate inhibited evaporation of the original pileus ice crystals in the warm phase of the ensuing gravity wave; fourth, through successive pulses, deep convection formed the observed <span class="hlt">layer</span> of TTL cirrus. While the general incidence and longevity of pileus <span class="hlt">cloud</span> remains unknown, in-situ measurements, and satellite-based Microwave Limb Sounder retrievals, suggest that much of the tropical TTL is sufficiently humid to be susceptible to its formation. Where these <span class="hlt">clouds</span> form and persist, there is potential for an irreversible repartition from water vapor to ice at cold temperatures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017ACP....17.4063S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017ACP....17.4063S"><span>Remote sensing and modelling analysis of the extreme dust storm hitting the <span class="hlt">Middle</span> East and eastern Mediterranean in September 2015</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Solomos, Stavros; Ansmann, Albert; Mamouri, Rodanthi-Elisavet; Binietoglou, Ioannis; Patlakas, Platon; Marinou, Eleni; Amiridis, Vassilis</p> <p>2017-03-01</p> <p>The extreme dust storm that affected the <span class="hlt">Middle</span> East and the eastern Mediterranean in September 2015 resulted in record-breaking dust loads over Cyprus with aerosol optical depth exceeding 5.0 at 550 nm. We analyse this event using profiles from the European Aerosol Research Lidar Network (EARLINET) and the <span class="hlt">Cloud</span>-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO), geostationary observations from the Meteosat Second Generation (MSG) Spinning Enhanced Visible and Infrared Imager (SEVIRI), and high-resolution simulations from the Regional Atmospheric Modeling System (RAMS). The analysis of modelling and remote sensing data reveals the main mechanisms that resulted in the generation and persistence of the dust <span class="hlt">cloud</span> over the <span class="hlt">Middle</span> East and Cyprus. A combination of meteorological and surface processes is found, including (a) the development of a thermal low in the area of Syria that results in unstable atmospheric conditions and dust mobilization in this area, (b) the convective activity over northern Iraq that triggers the formation of westward-moving haboobs that merge with the previously elevated dust <span class="hlt">layer</span>, and (c) the changes in land use due to war in the areas of northern Iraq and Syria that enhance dust erodibility.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015SPIE.9794E..2QW','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015SPIE.9794E..2QW"><span><span class="hlt">Cloud</span>-based robot remote control system for smart factory</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wu, Zhiming; Li, Lianzhong; Xu, Yang; Zhai, Jingmei</p> <p>2015-12-01</p> <p>With the development of internet technologies and the wide application of robots, there is a prospect (trend/tendency) of integration between network and robots. A <span class="hlt">cloud</span>-based robot remote control system over networks for smart factory is proposed, which enables remote users to control robots and then realize intelligent production. To achieve it, a three-<span class="hlt">layer</span> system architecture is designed including user <span class="hlt">layer</span>, service <span class="hlt">layer</span> and physical <span class="hlt">layer</span>. Remote control applications running on the <span class="hlt">cloud</span> server is developed on Microsoft Azure. Moreover, DIV+ CSS technologies are used to design human-machine interface to lower maintenance cost and improve development efficiency. Finally, an experiment is implemented to verify the feasibility of the program.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018ClDy...50.3097F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018ClDy...50.3097F"><span>The influence of extratropical <span class="hlt">cloud</span> phase and amount feedbacks on climate sensitivity</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Frey, William R.; Kay, Jennifer E.</p> <p>2018-04-01</p> <p>Global coupled climate models have large long-standing <span class="hlt">cloud</span> and radiation biases, calling into question their ability to simulate climate and climate change. This study assesses the impact of reducing shortwave radiation biases on climate sensitivity within the Community Earth System Model (CESM). The model is modified by increasing supercooled <span class="hlt">cloud</span> liquid to better match absorbed shortwave radiation observations over the Southern Ocean while tuning to reduce a compensating tropical shortwave bias. With a thermodynamic mixed-<span class="hlt">layer</span> ocean, equilibrium warming in response to doubled CO2 increases from 4.1 K in the control to 5.6 K in the modified model. This 1.5 K increase in equilibrium climate sensitivity is caused by changes in two extratropical shortwave <span class="hlt">cloud</span> feedbacks. First, reduced conversion of <span class="hlt">cloud</span> ice to liquid at high southern latitudes decreases the magnitude of a negative <span class="hlt">cloud</span> phase feedback. Second, warming is amplified in the mid-latitudes by a larger positive shortwave <span class="hlt">cloud</span> feedback. The positive <span class="hlt">cloud</span> feedback, usually associated with the subtropics, arises when sea surface warming increases the moisture gradient between the boundary <span class="hlt">layer</span> and free troposphere. The increased moisture gradient enhances the effectiveness of mixing to dry the boundary <span class="hlt">layer</span>, which decreases <span class="hlt">cloud</span> amount and optical depth. When a full-depth ocean with dynamics and thermodynamics is included, ocean heat uptake preferentially cools the mid-latitude Southern Ocean, partially inhibiting the positive <span class="hlt">cloud</span> feedback and slowing warming. Overall, the results highlight strong connections between Southern Ocean mixed-phase <span class="hlt">cloud</span> partitioning, <span class="hlt">cloud</span> feedbacks, and ocean heat uptake in a climate forced by greenhouse gas changes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1416676','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1416676"><span>Marine <span class="hlt">cloud</span> brightening – as effective without <span class="hlt">clouds</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Ahlm, Lars; Jones, Andy; Stjern, Camilla W.</p> <p></p> <p>Marine <span class="hlt">cloud</span> brightening through sea spray injection has been proposed as a climate engineering method for avoiding the most severe consequences of global warming. A limitation of most of the previous modelling studies on marine <span class="hlt">cloud</span> brightening is that they have either considered individual models or only investigated the effects of a specific increase in the number of <span class="hlt">cloud</span> droplets. Here we present results from coordinated simulations with three Earth system models (ESMs) participating in the Geoengineering Model Intercomparison Project (GeoMIP) G4sea-salt experiment. Injection rates of accumulation-mode sea spray aerosol particles over ocean between 30°N and 30°S are set in each model tomore » generate a global-mean effective radiative forcing (ERF) of –2.0 W m –2 at the top of the atmosphere. We find that the injection increases the <span class="hlt">cloud</span> droplet number concentration in lower <span class="hlt">layers</span>, reduces the <span class="hlt">cloud</span>-top effective droplet radius, and increases the <span class="hlt">cloud</span> optical depth over the injection area. We also find, however, that the global-mean clear-sky ERF by the injected particles is as large as the corresponding total ERF in all three ESMs, indicating a large potential of the aerosol direct effect in regions of low cloudiness. The largest enhancement in ERF due to the presence of <span class="hlt">clouds</span> occur as expected in the subtropical stratocumulus regions off the west coasts of the American and African continents. However, outside these regions, the ERF is in general equally large in cloudy and clear-sky conditions. Lastly, these findings suggest a more important role of the aerosol direct effect in sea spray climate engineering than previously thought.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1416676-marine-cloud-brightening-effective-without-clouds','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1416676-marine-cloud-brightening-effective-without-clouds"><span>Marine <span class="hlt">cloud</span> brightening – as effective without <span class="hlt">clouds</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Ahlm, Lars; Jones, Andy; Stjern, Camilla W.; ...</p> <p>2017-11-06</p> <p>Marine <span class="hlt">cloud</span> brightening through sea spray injection has been proposed as a climate engineering method for avoiding the most severe consequences of global warming. A limitation of most of the previous modelling studies on marine <span class="hlt">cloud</span> brightening is that they have either considered individual models or only investigated the effects of a specific increase in the number of <span class="hlt">cloud</span> droplets. Here we present results from coordinated simulations with three Earth system models (ESMs) participating in the Geoengineering Model Intercomparison Project (GeoMIP) G4sea-salt experiment. Injection rates of accumulation-mode sea spray aerosol particles over ocean between 30°N and 30°S are set in each model tomore » generate a global-mean effective radiative forcing (ERF) of –2.0 W m –2 at the top of the atmosphere. We find that the injection increases the <span class="hlt">cloud</span> droplet number concentration in lower <span class="hlt">layers</span>, reduces the <span class="hlt">cloud</span>-top effective droplet radius, and increases the <span class="hlt">cloud</span> optical depth over the injection area. We also find, however, that the global-mean clear-sky ERF by the injected particles is as large as the corresponding total ERF in all three ESMs, indicating a large potential of the aerosol direct effect in regions of low cloudiness. The largest enhancement in ERF due to the presence of <span class="hlt">clouds</span> occur as expected in the subtropical stratocumulus regions off the west coasts of the American and African continents. However, outside these regions, the ERF is in general equally large in cloudy and clear-sky conditions. Lastly, these findings suggest a more important role of the aerosol direct effect in sea spray climate engineering than previously thought.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/1054049-climatology-formation-tropical-midlevel-clouds-darwin-arm-site','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/1054049-climatology-formation-tropical-midlevel-clouds-darwin-arm-site"><span>Climatology and Formation of Tropical Midlevel <span class="hlt">Clouds</span> at the Darwin ARM Site</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Riihimaki, Laura D.; McFarlane, Sally A.; Comstock, Jennifer M.</p> <p></p> <p>A 4-yr climatology of midlevel <span class="hlt">clouds</span> is presented from vertically pointing <span class="hlt">cloud</span> lidar and radar measurements at the Atmospheric Radiation Measurement Program (ARM) site at Darwin, Australia. Few studies exist of tropical midlevel <span class="hlt">clouds</span> using a dataset of this length. Seventy percent of <span class="hlt">clouds</span> with top heights between 4 and 8 km are less than 2 km thick. These thin <span class="hlt">layer</span> <span class="hlt">clouds</span> have a peak in <span class="hlt">cloud</span>-top temperature around the melting level (0°C) and also a second peak around -12.5°C. The diurnal frequency of thin <span class="hlt">clouds</span> is highest during the night and reaches a minimum around noon, consistent with variationmore » caused by solar heating. Using a 1.5-yr subset of the observations, the authors found that thin <span class="hlt">clouds</span> have a high probability of containing supercooled liquid water at low temperatures: ~20% of <span class="hlt">clouds</span> at -30°C, ~50% of <span class="hlt">clouds</span> at -20°C, and ~65% of <span class="hlt">clouds</span> at -10°C contain supercooled liquid water. The authors hypothesize that thin midlevel <span class="hlt">clouds</span> formed at the melting level are formed differently during active and break monsoon periods and test this over three monsoon seasons. A greater frequency of thin midlevel <span class="hlt">clouds</span> are likely formed by increased condensation following the latent cooling of melting during active monsoon periods when stratiform precipitation is most frequent. This is supported by the high percentage (65%) of midlevel <span class="hlt">clouds</span> with preceding stratiform precipitation and the high frequency of stable <span class="hlt">layers</span> slightly warmer than 0°C. In the break monsoon, a distinct peak in the frequency of stable <span class="hlt">layers</span> at 0°C matches the peak in thin midlevel cloudiness, consistent with detrainment from convection.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.A11J0138N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.A11J0138N"><span>Observed Aerosol Influence on Ice Water Content of Arctic Mixed-Phase <span class="hlt">Clouds</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Norgren, M.; de Boer, G.; Shupe, M.</p> <p>2016-12-01</p> <p>The response of ice water content (IWC) in Arctic mixed-phase stratocumulus to atmospheric aerosols is observed. IWC retrievals from ground based radars operated by the Atmospheric Radiation Measurement (ARM) program in Barrow, Alaska are used to construct composite profiles of <span class="hlt">cloud</span> IWC from a 9-year radar record starting in January of 2000. The IWC profiles for high (polluted) and low (clean) aerosol loadings are compared. Generally, we find that clean <span class="hlt">clouds</span> exhibit statistically significant higher levels of IWC than do polluted <span class="hlt">clouds</span> by a factor of 2-4 at <span class="hlt">cloud</span> base. For springtime <span class="hlt">clouds</span>, with a maximum relative humidity with respect to ice (RHI) above 110% in the <span class="hlt">cloud</span> <span class="hlt">layer</span>, the IWC at <span class="hlt">cloud</span> base was a factor of 3.25 times higher in clean <span class="hlt">clouds</span> than it was in polluted <span class="hlt">clouds</span>. We infer that the aerosol loading of the <span class="hlt">cloud</span> environment alters the liquid drop size distribution within the <span class="hlt">cloud</span>, with larger drops being more frequent in clean <span class="hlt">clouds</span>. Larger <span class="hlt">cloud</span> drops promote riming within the <span class="hlt">cloud</span> <span class="hlt">layer</span>, which is one explanation for the higher IWC levels in clean <span class="hlt">clouds</span>. The drop size distribution may also be a significant control of ice nucleation events within mixed-phase <span class="hlt">clouds</span>. Whether the high IWC levels in clean <span class="hlt">clouds</span> are due to increased riming or nucleation events is unclear at this time.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20060051527&hterms=field+infrared&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DNear%2Bfield%2Binfrared','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20060051527&hterms=field+infrared&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DNear%2Bfield%2Binfrared"><span>On Cirrus <span class="hlt">Cloud</span> Fields Measured by the Atmospheric Infrared Sounder</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kahn, Brian H.; Eldering, Annmarie; Liou, Kuo Nan</p> <p>2006-01-01</p> <p>A viewgraph presentation showing trends in <span class="hlt">clouds</span> measured by the Atmospheric Infrared Sounder (AIRS) is given. The topics include: 1) Trends in <span class="hlt">clouds</span> measured by AIRS: Are they reasonable? 2) Single and multilayered <span class="hlt">cloud</span> trends; 3) Retrievals of thin cirrus D(sub e) and tau: Single-<span class="hlt">layered</span> <span class="hlt">cloud</span> only; 4) Relationships between ECF, D(sub e), tau, and T(sub CLD); and 5) MODIS vs. AIRS retrievals.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1345766','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1345766"><span>Aerosol and <span class="hlt">cloud</span> microphysics covariability in the northeast Pacific boundary <span class="hlt">layer</span> estimated with ship-based and satellite remote sensing observations</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Painemal, David; Chiu, J. -Y. Christine; Minnis, Patrick</p> <p></p> <p>We utilized ship measurements collected over the northeast Pacific along transects between the port of Los Angeles (33.7°N, 118.2°W) and Honolulu (21.3°N, 157.8°W) during May to August 2013 in order to investigate the covariability between marine low <span class="hlt">cloud</span> microphysical and aerosol properties. Ship-based retrievals of <span class="hlt">cloud</span> optical depth (τ) from a Sun photometer and liquid water path (LWP) from a microwave radiometer were combined to derive <span class="hlt">cloud</span> droplet number concentration N d and compute a <span class="hlt">cloud</span>-aerosol interaction (ACI) metric defined as ACI CCN=∂ ln(N d)/∂ ln(CCN), with CCN denoting the <span class="hlt">cloud</span> condensation nuclei concentration measured at 0.4% (CCN 0.4) andmore » 0.3% (CCN 0.3) supersaturation. Analysis of CCN 0.4, accumulation mode aerosol concentration (N a), and extinction coefficient (σ ext) indicates that N a and σ ext can be used as CCN 0.4 proxies for estimating ACI. ACI CCN derived from 10 min averaged N d and CCN 0.4 and CCN 0.3, and CCN 0.4 regressions using N a and σ ext, produce high ACI CCN: near 1.0, that is, a fractional change in aerosols is associated with an equivalent fractional change in Nd. ACI CCN computed in deep boundary <span class="hlt">layers</span> was small (ACI CCN=0.60), indicating that surface aerosol measurements inadequately represent the aerosol variability below <span class="hlt">clouds</span>. Satellite <span class="hlt">cloud</span> retrievals from MODerate-resolution Imaging Spectroradiometer and GOES-15 data were compared against ship-based retrievals and further analyzed to compute a satellite-based ACI CCN. We found that the satellite data correlated well with their ship-based counterparts with linear correlation coefficients equal to or greater than 0.78. Combined satellite Nd and ship-based CCN 0.4 and Na yielded a maximum ACI CCN=0.88–0.92, a value slightly less than the ship-based ACI CCN, but still consistent with aircraft-based studies in the eastern Pacific.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1345766-aerosol-cloud-microphysics-covariability-northeast-pacific-boundary-layer-estimated-ship-based-satellite-remote-sensing-observations','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1345766-aerosol-cloud-microphysics-covariability-northeast-pacific-boundary-layer-estimated-ship-based-satellite-remote-sensing-observations"><span>Aerosol and <span class="hlt">cloud</span> microphysics covariability in the northeast Pacific boundary <span class="hlt">layer</span> estimated with ship-based and satellite remote sensing observations</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Painemal, David; Chiu, J. -Y. Christine; Minnis, Patrick; ...</p> <p>2017-02-27</p> <p>We utilized ship measurements collected over the northeast Pacific along transects between the port of Los Angeles (33.7°N, 118.2°W) and Honolulu (21.3°N, 157.8°W) during May to August 2013 in order to investigate the covariability between marine low <span class="hlt">cloud</span> microphysical and aerosol properties. Ship-based retrievals of <span class="hlt">cloud</span> optical depth (τ) from a Sun photometer and liquid water path (LWP) from a microwave radiometer were combined to derive <span class="hlt">cloud</span> droplet number concentration N d and compute a <span class="hlt">cloud</span>-aerosol interaction (ACI) metric defined as ACI CCN=∂ ln(N d)/∂ ln(CCN), with CCN denoting the <span class="hlt">cloud</span> condensation nuclei concentration measured at 0.4% (CCN 0.4) andmore » 0.3% (CCN 0.3) supersaturation. Analysis of CCN 0.4, accumulation mode aerosol concentration (N a), and extinction coefficient (σ ext) indicates that N a and σ ext can be used as CCN 0.4 proxies for estimating ACI. ACI CCN derived from 10 min averaged N d and CCN 0.4 and CCN 0.3, and CCN 0.4 regressions using N a and σ ext, produce high ACI CCN: near 1.0, that is, a fractional change in aerosols is associated with an equivalent fractional change in Nd. ACI CCN computed in deep boundary <span class="hlt">layers</span> was small (ACI CCN=0.60), indicating that surface aerosol measurements inadequately represent the aerosol variability below <span class="hlt">clouds</span>. Satellite <span class="hlt">cloud</span> retrievals from MODerate-resolution Imaging Spectroradiometer and GOES-15 data were compared against ship-based retrievals and further analyzed to compute a satellite-based ACI CCN. We found that the satellite data correlated well with their ship-based counterparts with linear correlation coefficients equal to or greater than 0.78. Combined satellite Nd and ship-based CCN 0.4 and Na yielded a maximum ACI CCN=0.88–0.92, a value slightly less than the ship-based ACI CCN, but still consistent with aircraft-based studies in the eastern Pacific.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.3991K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.3991K"><span>Understanding rapid changes in phase partitioning between <span class="hlt">cloud</span> liquid and ice in an Arctic stratiform mixed-phase <span class="hlt">cloud</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kalesse, Heike; de Boer, Gijs; Solomon, Amy; Oue, Mariko; Ahlgrimm, Maike; Zhang, Damao; Shupe, Matthew; Luke, Edward; Protat, Alain</p> <p>2016-04-01<