Global Lidar Measurements of Clouds and Aerosols from Space Using the Geoscience Laser Altimeter System (GLAS)

NASA Technical Reports Server (NTRS)

Hlavka, Dennis L.; Palm, S. P.; Welton, E. J.; Hart, W. D.; Spinhirne, J. D.; McGill, M.; Mahesh, A.; Starr, David OC. (Technical Monitor)

2001-01-01

The Geoscience Laser Altimeter System (GLAS) is scheduled for launch on the ICESat satellite as part of the NASA EOS mission in 2002. GLAS will be used to perform high resolution surface altimetry and will also provide a continuously operating atmospheric lidar to profile clouds, aerosols, and the planetary boundary layer with horizontal and vertical resolution of 175 and 76.8 m, respectively. GLAS is the first active satellite atmospheric profiler to provide global coverage. Data products include direct measurements of the heights of aerosol and cloud layers, and the optical depth of transmissive layers. In this poster we provide an overview of the GLAS atmospheric data products, present a simulated GLAS data set, and show results from the simulated data set using the GLAS data processing algorithm. Optical results from the ER-2 Cloud Physics Lidar (CPL), which uses many of the same processing algorithms as GLAS, show algorithm performance with real atmospheric conditions during the Southern African Regional Science Initiative (SAFARI 2000).

Self-consistent atmosphere modeling with cloud formation for low-mass stars and exoplanets

NASA Astrophysics Data System (ADS)

Juncher, Diana; Jørgensen, Uffe G.; Helling, Christiane

2017-12-01

Context. Low-mass stars and extrasolar planets have ultra-cool atmospheres where a rich chemistry occurs and clouds form. The increasing amount of spectroscopic observations for extrasolar planets requires self-consistent model atmosphere simulations to consistently include the formation processes that determine cloud formation and their feedback onto the atmosphere. Aims: Our aim is to complement the MARCS model atmosphere suit with simulations applicable to low-mass stars and exoplanets in preparation of E-ELT, JWST, PLATO and other upcoming facilities. Methods: The MARCS code calculates stellar atmosphere models, providing self-consistent solutions of the radiative transfer and the atmospheric structure and chemistry. We combine MARCS with a kinetic model that describes cloud formation in ultra-cool atmospheres (seed formation, growth/evaporation, gravitational settling, convective mixing, element depletion). Results: We present a small grid of self-consistently calculated atmosphere models for Teff = 2000-3000 K with solar initial abundances and log (g) = 4.5. Cloud formation in stellar and sub-stellar atmospheres appears for Teff < 2700 K and has a significant effect on the structure and the spectrum of the atmosphere for Teff < 2400 K. We have compared the synthetic spectra of our models with observed spectra and found that they fit the spectra of mid- to late-type M-dwarfs and early-type L-dwarfs well. The geometrical extension of the atmospheres (at τ = 1) changes with wavelength resulting in a flux variation of 10%. This translates into a change in geometrical extension of the atmosphere of about 50 km, which is the quantitative basis for exoplanetary transit spectroscopy. We also test DRIFT-MARCS for an example exoplanet and demonstrate that our simulations reproduce the Spitzer observations for WASP-19b rather well for Teff = 2600 K, log (g) = 3.2 and solar abundances. Our model points at an exoplanet with a deep cloud-free atmosphere with a substantial day-night energy transport and no temperature inversion.

Identification of Regime Transitions in Umbrella Cloud Growth for Short- and Long-Lived Eruptions

NASA Astrophysics Data System (ADS)

Pouget, S.; Bursik, M. I.; Johnson, C. G.; Hogg, A. J.; Sparks, R. S. J.; Phillips, J.

2014-12-01

The ability to characterize the transition between fluid dynamic regimes in an umbrella cloud as it spreads as a gravity current is important for volcanologists and atmospheric scientists. It would allow a better understanding of how ash behaves and spreads in the atmosphere and therefore better estimate the location and propagation of the ash during an eruption. We tested a new gravity current model that allows us to study the transition from one flow regime to another in data plume growth data from several eruptions. It was found that previous asymptotic models of umbrella cloud growth only treat one part of the evolution of the cloud. The new model allows for the study of the duration of different regimes and the timing of transitions during growth of the umbrella cloud. It was found, by testing the effect of the different input parameters of the model, that the duration of release from the volcanic source has a larger impact than the drag force and the initial radius of the intrusion on the initial and downwind spreading.

Formation of highly porous aerosol particles by atmospheric freeze-drying in ice clouds

PubMed Central

Adler, Gabriela; Koop, Thomas; Haspel, Carynelisa; Taraniuk, Ilya; Moise, Tamar; Koren, Ilan; Heiblum, Reuven H.; Rudich, Yinon

2013-01-01

The cycling of atmospheric aerosols through clouds can change their chemical and physical properties and thus modify how aerosols affect cloud microphysics and, subsequently, precipitation and climate. Current knowledge about aerosol processing by clouds is rather limited to chemical reactions within water droplets in warm low-altitude clouds. However, in cold high-altitude cirrus clouds and anvils of high convective clouds in the tropics and midlatitudes, humidified aerosols freeze to form ice, which upon exposure to subsaturation conditions with respect to ice can sublimate, leaving behind residual modified aerosols. This freeze-drying process can occur in various types of clouds. Here we simulate an atmospheric freeze-drying cycle of aerosols in laboratory experiments using proxies for atmospheric aerosols. We find that aerosols that contain organic material that undergo such a process can form highly porous aerosol particles with a larger diameter and a lower density than the initial homogeneous aerosol. We attribute this morphology change to phase separation upon freezing followed by a glass transition of the organic material that can preserve a porous structure after ice sublimation. A porous structure may explain the previously observed enhancement in ice nucleation efficiency of glassy organic particles. We find that highly porous aerosol particles scatter solar light less efficiently than nonporous aerosol particles. Using a combination of satellite and radiosonde data, we show that highly porous aerosol formation can readily occur in highly convective clouds, which are widespread in the tropics and midlatitudes. These observations may have implications for subsequent cloud formation cycles and aerosol albedo near cloud edges. PMID:24297908

Formation of highly porous aerosol particles by atmospheric freeze-drying in ice clouds.

PubMed

Adler, Gabriela; Koop, Thomas; Haspel, Carynelisa; Taraniuk, Ilya; Moise, Tamar; Koren, Ilan; Heiblum, Reuven H; Rudich, Yinon

2013-12-17

The cycling of atmospheric aerosols through clouds can change their chemical and physical properties and thus modify how aerosols affect cloud microphysics and, subsequently, precipitation and climate. Current knowledge about aerosol processing by clouds is rather limited to chemical reactions within water droplets in warm low-altitude clouds. However, in cold high-altitude cirrus clouds and anvils of high convective clouds in the tropics and midlatitudes, humidified aerosols freeze to form ice, which upon exposure to subsaturation conditions with respect to ice can sublimate, leaving behind residual modified aerosols. This freeze-drying process can occur in various types of clouds. Here we simulate an atmospheric freeze-drying cycle of aerosols in laboratory experiments using proxies for atmospheric aerosols. We find that aerosols that contain organic material that undergo such a process can form highly porous aerosol particles with a larger diameter and a lower density than the initial homogeneous aerosol. We attribute this morphology change to phase separation upon freezing followed by a glass transition of the organic material that can preserve a porous structure after ice sublimation. A porous structure may explain the previously observed enhancement in ice nucleation efficiency of glassy organic particles. We find that highly porous aerosol particles scatter solar light less efficiently than nonporous aerosol particles. Using a combination of satellite and radiosonde data, we show that highly porous aerosol formation can readily occur in highly convective clouds, which are widespread in the tropics and midlatitudes. These observations may have implications for subsequent cloud formation cycles and aerosol albedo near cloud edges.

Thermal disequilibrium at the top of volcanic clouds and its effect on estimates of the column height

NASA Technical Reports Server (NTRS)

Woods, Andrew W.; Self, Stephen

1992-01-01

Satellite images of large volcanic explosions reveal that the tops of volcanic eruptions columns are much cooler than the surrounding atmosphere. It is proposed that this effect occurs whenever a mixture of hot volcanic ash and entrained air ascends sufficiently high into a stably stratified atmosphere. Although the mixture is initially very hot, it expands and cools as the ambient pressure decreases. It is shown that cloud-top undercoolings in excess of 20 C may develop in clouds that penetrate the stratosphere, and it is predicted that, for a given cloud-top temperature, variations in the initial temperature of 100-200 C may correspond to variations in the column height of 5-10 km. It is deduced that the present practice of converting satellite-based measurements of the temperature at the top of volcanic eruptions columns to estimates of the column height will produce rather inaccurate results and should therefore be discontinued.

Evaluation of RRTMG and Fu-Liou RTM Performance against LBLRTM-DISORT Simulations and CERES Data in terms of Ice Clouds Radiative Effects

NASA Astrophysics Data System (ADS)

Gu, B.; Yang, P.; Kuo, C. P.; Mlawer, E. J.

2017-12-01

Evaluation of RRTMG and Fu-Liou RTM Performance against LBLRTM-DISORT Simulations and CERES Data in terms of Ice Clouds Radiative Effects Boyan Gu1, Ping Yang1, Chia-Pang Kuo1, Eli J. Mlawer2 Department of Atmospheric Sciences, Texas A&M University, College Station, TX 77843, USA Atmospheric and Environmental Research (AER), Lexington, MA 02421, USA Ice clouds play an important role in climate system, especially in the Earth's radiation balance and hydrological cycle. However, the representation of ice cloud radiative effects (CRE) remains significant uncertainty, because scattering properties of ice clouds are not well considered in general circulation models (GCM). We analyze the strengths and weakness of the Rapid Radiative Transfer Model for GCM Applications (RRTMG) and Fu-Liou Radiative Transfer Model (RTM) against rigorous LBLRTM-DISORT (a combination of Line-By-Line Radiative Transfer Model and Discrete Ordinate Radiative Transfer Model) calculations and CERES (Clouds and the Earth's Radiant Energy System) flux observations. In total, 6 US standard atmospheric profiles and 42 atmospheric profiles from Atmospheric and Environmental Research (AER) Company are used to evaluate the RRTMG and Fu-Liou RTM by LBLRTM-DISORT calculations from 0 to 3250 cm-1. Ice cloud radiative effect simulations with RRTMG and Fu-Liou RTM are initialized using the ice cloud properties from MODIS collection-6 products. Simulations of single layer ice cloud CRE by RRTMG and LBLRTM-DISORT show that RRTMG, neglecting scattering, overestimates the TOA flux by about 0-15 W/m2 depending on the cloud particle size and optical depth, and the most significant overestimation occurs when the particle effective radius is small (around 10 μm) and the cloud optical depth is intermediate (about 1-10). The overestimation reduces significantly when the similarity rule is applied to RRTMG. We combine ice cloud properties from MODIS Collection-6 and atmospheric profiles from the Modern-Era Retrospective Analysis for Research and Applications-2 (MERRA2) reanalysis to simulate ice cloud CRE, which is compared with CERES observations.

Determination of Cloud Base Height, Wind Velocity, and Short-Range Cloud Structure Using Multiple Sky Imagers Field Campaign Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Dong; Schwartz, Stephen E.; Yu, Dantong

Clouds are a central focus of the U.S. Department of Energy (DOE)’s Atmospheric System Research (ASR) program and Atmospheric Radiation Measurement (ARM) Climate Research Facility, and more broadly are the subject of much investigation because of their important effects on atmospheric radiation and, through feedbacks, on climate sensitivity. Significant progress has been made by moving from a vertically pointing (“soda-straw”) to a three-dimensional (3D) view of clouds by investing in scanning cloud radars through the American Recovery and Reinvestment Act of 2009. Yet, because of the physical nature of radars, there are key gaps in ARM's cloud observational capabilities. Formore » example, cloud radars often fail to detect small shallow cumulus and thin cirrus clouds that are nonetheless radiatively important. Furthermore, it takes five to twenty minutes for a cloud radar to complete a 3D volume scan and clouds can evolve substantially during this period. Ground-based stereo-imaging is a promising technique to complement existing ARM cloud observation capabilities. It enables the estimation of cloud coverage, height, horizontal motion, morphology, and spatial arrangement over an extended area of up to 30 by 30 km at refresh rates greater than 1 Hz (Peng et al. 2015). With fine spatial and temporal resolution of modern sky cameras, the stereo-imaging technique allows for the tracking of a small cumulus cloud or a thin cirrus cloud that cannot be detected by a cloud radar. With support from the DOE SunShot Initiative, the Principal Investigator (PI)’s team at Brookhaven National Laboratory (BNL) has developed some initial capability for cloud tracking using multiple distinctly located hemispheric cameras (Peng et al. 2015). To validate the ground-based cloud stereo-imaging technique, the cloud stereo-imaging field campaign was conducted at the ARM Facility’s Southern Great Plains (SGP) site in Oklahoma from July 15 to December 24. As shown in Figure 1, the cloud stereo-imaging system consisted of two inexpensive high-definition (HD) hemispheric cameras (each cost less than $1,500) and ARM’s Total Sky Imager (TSI). Together with other co-located ARM instrumentation, the campaign provides a promising opportunity to validate stereo-imaging-based cloud base height and, more importantly, to examine the feasibility of cloud thickness retrieval for low-view-angle clouds.« less

Aerosol specification in single-column Community Atmosphere Model version 5

DOE PAGES

Lebassi-Habtezion, B.; Caldwell, P. M.

2015-03-27

Single-column model (SCM) capability is an important tool for general circulation model development. In this study, the SCM mode of version 5 of the Community Atmosphere Model (CAM5) is shown to handle aerosol initialization and advection improperly, resulting in aerosol, cloud-droplet, and ice crystal concentrations which are typically much lower than observed or simulated by CAM5 in global mode. This deficiency has a major impact on stratiform cloud simulations but has little impact on convective case studies because aerosol is currently not used by CAM5 convective schemes and convective cases are typically longer in duration (so initialization is less important).more » By imposing fixed aerosol or cloud-droplet and crystal number concentrations, the aerosol issues described above can be avoided. Sensitivity studies using these idealizations suggest that the Meyers et al. (1992) ice nucleation scheme prevents mixed-phase cloud from existing by producing too many ice crystals. Microphysics is shown to strongly deplete cloud water in stratiform cases, indicating problems with sequential splitting in CAM5 and the need for careful interpretation of output from sequentially split climate models. Droplet concentration in the general circulation model (GCM) version of CAM5 is also shown to be far too low (~ 25 cm −3) at the southern Great Plains (SGP) Atmospheric Radiation Measurement (ARM) site.« less

An improved hindcast approach for evaluation and diagnosis of physical processes in global climate models

DOE PAGES

Ma, H. -Y.; Chuang, C. C.; Klein, S. A.; ...

2015-11-06

Here, we present an improved procedure of generating initial conditions (ICs) for climate model hindcast experiments with specified sea surface temperature and sea ice. The motivation is to minimize errors in the ICs and lead to a better evaluation of atmospheric parameterizations' performance in the hindcast mode. We apply state variables (horizontal velocities, temperature and specific humidity) from the operational analysis/reanalysis for the atmospheric initial states. Without a data assimilation system, we apply a two-step process to obtain other necessary variables to initialize both the atmospheric (e.g., aerosols and clouds) and land models (e.g., soil moisture). First, we nudge onlymore » the model horizontal velocities towards operational analysis/reanalysis values, given a 6-hour relaxation time scale, to obtain all necessary variables. Compared to the original strategy in which horizontal velocities, temperature and specific humidity are nudged, the revised approach produces a better representation of initial aerosols and cloud fields which are more consistent and closer to observations and model's preferred climatology. Second, we obtain land ICs from an offline land model simulation forced with observed precipitation, winds, and surface fluxes. This approach produces more realistic soil moisture in the land ICs. With this refined procedure, the simulated precipitation, clouds, radiation, and surface air temperature over land are improved in the Day 2 mean hindcasts. Following this procedure, we propose a “Core” integration suite which provides an easily repeatable test allowing model developers to rapidly assess the impacts of various parameterization changes on the fidelity of modelled cloud-associated processes relative to observations.« less

An improved hindcast approach for evaluation and diagnosis of physical processes in global climate models

NASA Astrophysics Data System (ADS)

Ma, H.-Y.; Chuang, C. C.; Klein, S. A.; Lo, M.-H.; Zhang, Y.; Xie, S.; Zheng, X.; Ma, P.-L.; Zhang, Y.; Phillips, T. J.

2015-12-01

We present an improved procedure of generating initial conditions (ICs) for climate model hindcast experiments with specified sea surface temperature and sea ice. The motivation is to minimize errors in the ICs and lead to a better evaluation of atmospheric parameterizations' performance in the hindcast mode. We apply state variables (horizontal velocities, temperature, and specific humidity) from the operational analysis/reanalysis for the atmospheric initial states. Without a data assimilation system, we apply a two-step process to obtain other necessary variables to initialize both the atmospheric (e.g., aerosols and clouds) and land models (e.g., soil moisture). First, we nudge only the model horizontal velocities toward operational analysis/reanalysis values, given a 6 h relaxation time scale, to obtain all necessary variables. Compared to the original strategy in which horizontal velocities, temperature, and specific humidity are nudged, the revised approach produces a better representation of initial aerosols and cloud fields which are more consistent and closer to observations and model's preferred climatology. Second, we obtain land ICs from an off-line land model simulation forced with observed precipitation, winds, and surface fluxes. This approach produces more realistic soil moisture in the land ICs. With this refined procedure, the simulated precipitation, clouds, radiation, and surface air temperature over land are improved in the Day 2 mean hindcasts. Following this procedure, we propose a "Core" integration suite which provides an easily repeatable test allowing model developers to rapidly assess the impacts of various parameterization changes on the fidelity of modeled cloud-associated processes relative to observations.

Atmospheric Polarization Imaging with Variable Aerosols and Clouds

DTIC Science & Technology

2010-12-10

based aerosol sensors to study the effect of variable clouds and aerosols on skylight polarization in the 450 – 780 nm spectral region. Near the end the...of skylight (either below the cloud or in a cloud-free portion of the sky), but that they often do not alter the angle of polarization beneath the...polarization. A relationship also was developed for an initial model of how increasing surface albedo reduces the overhead skylight polarization. 15

Cloudy Sounding and Cloud-Top Height Retrieval From AIRS Alone Single Field-of-View Radiance Measurements

NASA Technical Reports Server (NTRS)

Weisz, Elisabeth; Li, Jun; Li, Jinlong; Zhou, Daniel K.; Huang, Hung-Lung; Goldberg, Mitchell D.; Yang, Ping

2007-01-01

High-spectral resolution measurements from the Atmospheric Infrared Sounder (AIRS) onboard the EOS (Earth Observing System) Aqua satellite provide unique information about atmospheric state, surface and cloud properties. This paper presents an AIRS alone single field-of-view (SFOV) retrieval algorithm to simultaneously retrieve temperature, humidity and ozone profiles under all weather conditions, as well as cloud top pressure (CTP) and cloud optical thickness (COT) under cloudy skies. For optically thick cloud conditions the above-cloud soundings are derived, whereas for clear skies and optically thin cloud conditions the profiles are retrieved from 0.005 hPa down to the earth's surface. Initial validation has been conducted by using the operational MODIS (Moderate Resolution Imaging Spectroradiometer) product, ECMWF (European Center of Medium range Weather Forecasts) analysis fields and radiosonde observations (RAOBs). These inter-comparisons clearly demonstrate the potential of this algorithm to process data from 38 high-spectral infrared (IR) sounder instruments.

Final definition and preliminary design study for the initial atmospheric cloud physics laboratory, a Spacelab mission payload

NASA Technical Reports Server (NTRS)

1976-01-01

The following areas related to the final definition and preliminary design study of the initial atmospheric cloud physics laboratory (ACPL) were covered: (1) proposal organization, personnel, schedule, and project management, (2) proposed configurations, (3) study objectives, (4) ACPL experiment program listing and description, (5) mission/flight flexibility and modularity/commonality, (6) study plan, and (7) description of following tasks: requirement analysis and definition task flow, systems analysis and trade studies, subsystem analysis and trade studies, specifications and interface control documents, preliminary design task flow, work breakdown structure, programmatic analysis and planning, and project costs. Finally, an overview of the scientific requirements was presented.

Current Sounding Capability From Satellite Meteorological Observation With Ultraspectral Infrared Instruments

NASA Technical Reports Server (NTRS)

Zhou, Daniel K.; Liu, Xu; Larar, Allen M.

2008-01-01

Ultraspectral resolution infrared spectral radiance obtained from near nadir observations provide atmospheric, surface, and cloud property information. The intent of the measurement of tropospheric thermodynamic state and trace abundances is the initialization of climate models and the monitoring of air quality. The NPOESS Airborne Sounder Testbed-Interferometer (NAST-I), designed to support the development of future satellite temperature and moisture sounders, aboard high altitude aircraft has been collecting data throughout many field campaigns. An advanced retrieval algorithm developed with NAST-I is now applied to satellite data collected with the Atmospheric InfraRed Sounder (AIRS) on the Aqua satellite launched on 4 May 2002 and the Infrared Atmospheric Sounding Interferometer (IASI) on the MetOp satellite launched on October 19, 2006. These instruments possess an ultra-spectral resolution, for example, both IASI and NAST-I have 0.25 cm-1 and a spectral coverage from 645 to 2760 cm-1. The retrieval algorithm with a fast radiative transfer model, including cloud effects, is used for atmospheric profile and cloud parameter retrieval. The physical inversion scheme has been developed, dealing with cloudy as well as cloud-free radiance observed with ultraspectral infrared sounders, to simultaneously retrieve surface, atmospheric thermodynamic, and cloud microphysical parameters. A fast radiative transfer model, which applies to the clouded atmosphere, is used for atmospheric profile and cloud parameter retrieval. A one-dimensional (1-d) variational multi-variable inversion solution is used to improve an iterative background state defined by an eigenvector-regression-retrieval. The solution is iterated in order to account for non-linearity in the 1-d variational solution. It is shown that relatively accurate temperature and moisture retrievals can be achieved below optically thin clouds. For optically thick clouds, accurate temperature and moisture profiles down to cloud top level are obtained. For both optically thin and thick cloud situations, the cloud top height can be retrieved with relatively high accuracy (i.e., error less than 1 km). Retrievals of atmospheric soundings, surface properties, and cloud microphysical properties with the AIRS and IASI observations are obtained and presented. These retrievals are further inter-compared with those obtained from airborne FTS system, such as the NPOESS Airborne Sounder Testbed? Interferometer (NAST I), dedicated dropsondes, radiosondes, and ground based Raman Lidar. The capabilities of satellite ultra-spectral sounder such as the AIRS and IASI are investigated. These advanced satellite ultraspectral infrared instruments are now playing an important role in satellite meteorological observation for numerical weather prediction.

On the Effect of Dust Particles on Global Cloud Condensation Nuclei and Cloud Droplet Number

NASA Technical Reports Server (NTRS)

Karydis, V. A.; Kumar, P.; Barahona, D.; Sokolik, I. N.; Nenes, A.

2011-01-01

Aerosol-cloud interaction studies to date consider aerosol with a substantial fraction of soluble material as the sole source of cloud condensation nuclei (CCN). Emerging evidence suggests that mineral dust can act as good CCN through water adsorption onto the surface of particles. This study provides a first assessment of the contribution of insoluble dust to global CCN and cloud droplet number concentration (CDNC). Simulations are carried out with the NASA Global Modeling Initiative chemical transport model with an online aerosol simulation, considering emissions from fossil fuel, biomass burning, marine, and dust sources. CDNC is calculated online and explicitly considers the competition of soluble and insoluble CCN for water vapor. The predicted annual average contribution of insoluble mineral dust to CCN and CDNC in cloud-forming areas is up to 40 and 23.8%, respectively. Sensitivity tests suggest that uncertainties in dust size distribution and water adsorption parameters modulate the contribution of mineral dust to CDNC by 23 and 56%, respectively. Coating of dust by hygroscopic salts during the atmospheric aging causes a twofold enhancement of the dust contribution to CCN; the aged dust, however, can substantially deplete in-cloud supersaturation during the initial stages of cloud formation and can eventually reduce CDNC. Considering the hydrophilicity from adsorption and hygroscopicity from solute is required to comprehensively capture the dust-warm cloud interactions. The framework presented here addresses this need and can be easily integrated in atmospheric models.

Simulations of arctic mixed-phase clouds in forecasts with CAM3 and AM2 for M-PACE

DOE PAGES

Xie, Shaocheng; Boyle, James; Klein, Stephen A.; ...

2008-02-27

[1] Simulations of mixed-phase clouds in forecasts with the NCAR Atmosphere Model version 3 (CAM3) and the GFDL Atmospheric Model version 2 (AM2) for the Mixed-Phase Arctic Cloud Experiment (M-PACE) are performed using analysis data from numerical weather prediction centers. CAM3 significantly underestimates the observed boundary layer mixed-phase cloud fraction and cannot realistically simulate the variations of liquid water fraction with temperature and cloud height due to its oversimplified cloud microphysical scheme. In contrast, AM2 reasonably reproduces the observed boundary layer cloud fraction while its clouds contain much less cloud condensate than CAM3 and the observations. The simulation of themore » boundary layer mixed-phase clouds and their microphysical properties is considerably improved in CAM3 when a new physically based cloud 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 clouds but does not help improve the simulation of the single-layer boundary layer clouds. AM2 simulated cloud fraction and LWP are sensitive to the change in cloud ice number concentrations used in the Wegener-Bergeron-Findeisen process while CAM3LIU only shows moderate sensitivity in its cloud 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 clouds.« less

Simulations of Arctic mixed-phase clouds in forecasts with CAM3 and AM2 for M-PACE

NASA Astrophysics Data System (ADS)

Xie, Shaocheng; Boyle, James; Klein, Stephen A.; Liu, Xiaohong; Ghan, Steven

2008-02-01

Simulations of mixed-phase clouds in forecasts with the NCAR Atmosphere Model version 3 (CAM3) and the GFDL Atmospheric Model version 2 (AM2) for the Mixed-Phase Arctic Cloud Experiment (M-PACE) are performed using analysis data from numerical weather prediction centers. CAM3 significantly underestimates the observed boundary layer mixed-phase cloud fraction and cannot realistically simulate the variations of liquid water fraction with temperature and cloud height due to its oversimplified cloud microphysical scheme. In contrast, AM2 reasonably reproduces the observed boundary layer cloud fraction while its clouds contain much less cloud condensate than CAM3 and the observations. The simulation of the boundary layer mixed-phase clouds and their microphysical properties is considerably improved in CAM3 when a new physically based cloud 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 clouds but does not help improve the simulation of the single-layer boundary layer clouds. AM2 simulated cloud fraction and LWP are sensitive to the change in cloud ice number concentrations used in the Wegener-Bergeron-Findeisen process while CAM3LIU only shows moderate sensitivity in its cloud 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 clouds.

The Role of Clouds in the Long-Term Habitability of Planets

NASA Technical Reports Server (NTRS)

Toon, Owen B.; Tolbert, Margaret

2000-01-01

We proposed to conduct theoretical and laboratory investigations of the role that clouds play in the long-term climate history of the Earth and other habitable planets. We made significant progress in the first area we proposed to consider- the properties of carbon dioxide clouds in atmospheres that are rich in carbon dioxide. We submitted a modeling paper on the microphysical properties of the clouds to Icarus showing that such clouds are unlikely to play an important role in the early greenhouses on Earth or Mars. The model was based on lab studies of the nucleation and growth of carbon dioxide. We have also submitted a manuscript describing these lab studies to Icarus. These lab studies are critical not only to the ancient Mars atmosphere, but also to the current one. We also submitted a paper to Nature describing modeling of current Martian CO2 clouds. We will also model the properties of water clouds in the early history of Earth. Early in Earth's history the atmosphere contained no free oxygen. Without oxygen, sulfate aerosols that are currently the dominant cloud nuclei, cannot form. Without such nuclei the cloud structure would have been far different than it is now. We initiated studies of the aerosols on Titan as part of this work. We reported these studies in a short paper on nucleation and in several conferences.

The Influence of Soil Moisture, Coastline Curvature, and Land-Breeze Circulations on Sea-Breeze Initiated Precipitation

NASA Technical Reports Server (NTRS)

Baker, David R.; Lynn, Barry H.; Boone, Aaron; Tao, Wei-Kuo; Simpson, Joanne

2000-01-01

Idealized numerical simulations are performed with a coupled atmosphere/land-surface model to identify the roles of initial soil moisture, coastline curvature, and land breeze circulations on sea breeze initiated precipitation. Data collected on 27 July 1991 during the Convection and Precipitation Electrification Experiment (CAPE) in central Florida are used. The 3D Goddard Cumulus Ensemble (GCE) cloud resolving model is coupled with the Goddard Parameterization for Land-Atmosphere-Cloud Exchange (PLACE) land surface model, thus providing a tool to simulate more realistically land-surface/atmosphere interaction and convective initiation. Eight simulations are conducted with either straight or curved coast-lines, initially homogeneous soil moisture or initially variable soil moisture, and initially homogeneous horizontal winds or initially variable horizontal winds (land breezes). All model simulations capture the diurnal evolution and general distribution of sea-breeze initiated precipitation over central Florida. The distribution of initial soil moisture influences the timing, intensity and location of subsequent precipitation. Soil moisture acts as a moisture source for the atmosphere, increases the connectively available potential energy, and thus preferentially focuses heavy precipitation over existing wet soil. Strong soil moisture-induced mesoscale circulations are not evident in these simulations. Coastline curvature has a major impact on the timing and location of precipitation. Earlier low-level convergence occurs inland of convex coastlines, and subsequent precipitation occurs earlier in simulations with curved coastlines. The presence of initial land breezes alone has little impact on subsequent precipitation. however, simulations with both coastline curvature and initial land breezes produce significantly larger peak rain rates due to nonlinear interactions.

A Madden-Julian oscillation event realistically simulated by a global cloud-resolving model.

PubMed

Miura, Hiroaki; Satoh, Masaki; Nasuno, Tomoe; Noda, Akira T; Oouchi, Kazuyoshi

2007-12-14

A Madden-Julian Oscillation (MJO) is a massive weather event consisting of deep convection coupled with atmospheric circulation, moving slowly eastward over the Indian and Pacific Oceans. Despite its enormous influence on many weather and climate systems worldwide, it has proven very difficult to simulate an MJO because of assumptions about cumulus clouds in global meteorological models. Using a model that allows direct coupling of the atmospheric circulation and clouds, we successfully simulated the slow eastward migration of an MJO event. Topography, the zonal sea surface temperature gradient, and interplay between eastward- and westward-propagating signals controlled the timing of the eastward transition of the convective center. Our results demonstrate the potential making of month-long MJO predictions when global cloud-resolving models with realistic initial conditions are used.

Initial Results from CALIPSO

NASA Technical Reports Server (NTRS)

Winker, David M.; Pelon, Jacques; McCormick, M. Patrick

2006-01-01

CALIPSO will carry the first polarization lidar in orbit, along with infrared and visible passive imagers, and will fly in formation as part of the Afternoon Constellation (A-train). The acquisition of observations which are simultaneous and coincident with observations from other instruments of the A-train will allow numerous synergies to be realized from combining CALIPSO observations with observations from other platforms. In particular, cloud observations from the CALIPSO lidar and the CloudSat radar will complement each other, together encompassing the variety of clouds found in the atmosphere, from thin cirrus to deep convective clouds. CALIPSO has been developed within the framework of a collaboration between NASA and CNES and is currently scheduled to launch, along with the CloudSat satellite, in spring 2006. This paper will present an overview of the CALIPSO mission, including initial results.

Atmospheric cloud physics laboratory project study

NASA Technical Reports Server (NTRS)

Schultz, W. E.; Stephen, L. A.; Usher, L. H.

1976-01-01

Engineering studies were performed for the Zero-G Cloud Physics Experiment liquid cooling and air pressure control systems. A total of four concepts for the liquid cooling system was evaluated, two of which were found to closely approach the systems requirements. Thermal insulation requirements, system hardware, and control sensor locations were established. The reservoir sizes and initial temperatures were defined as well as system power requirements. In the study of the pressure control system, fluid analyses by the Atmospheric Cloud Physics Laboratory were performed to determine flow characteristics of various orifice sizes, vacuum pump adequacy, and control systems performance. System parameters predicted in these analyses as a function of time include the following for various orifice sizes: (1) chamber and vacuum pump mass flow rates, (2) the number of valve openings or closures, (3) the maximum cloud chamber pressure deviation from the allowable, and (4) cloud chamber and accumulator pressure.

Implementation of Cloud Retrievals for Tropospheric Emission Spectrometer (TES) Atmospheric Retrievals: Part 1. Description and Characterization of Errors on Trace Gas Retrievals

NASA Technical Reports Server (NTRS)

Kulawik, Susan S.; Worden, John; Eldering, Annmarie; Bowman, Kevin; Gunson, Michael; Osterman, Gregory B.; Zhang, Lin; Clough, Shepard A.; Shephard, Mark W.; Beer, Reinhard

2006-01-01

We develop an approach to estimate and characterize trace gas retrievals in the presence of clouds in high spectral measurements of upwelling radiance in the infrared spectral region (650-2260/cm). The radiance contribution of clouds is parameterized in terms of a set of frequency-dependent nonscattering optical depths and a cloud height. These cloud parameters are retrieved jointly with surface temperature, emissivity, atmospheric temperature, and trace gases such as ozone from spectral data. We demonstrate the application of this approach using data from the Tropospheric Emission Spectrometer (TES) and test data simulated with a scattering radiative transfer model. We show the value of this approach in that it results in accurate estimates of errors for trace gas retrievals, and the retrieved values improve over the initial guess for a wide range of cloud conditions. Comparisons are made between TES retrievals of ozone, temperature, and water to model fields from the Global Modeling and Assimilation Office (GMAO), temperature retrievals from the Atmospheric Infrared Sounder (AIRS), tropospheric ozone columns from the Goddard Earth Observing System (GEOS) GEOS-Chem, and ozone retrievals from the Total Ozone Mapping Spectrometer (TOMS). In each of these cases, this cloud retrieval approach does not introduce observable biases into TES retrievals.

Phase B: Final definition and preliminary design study for the initial Atmospheric Cloud Physics Laboratory (ACPL), a spacelab mission payload

NASA Technical Reports Server (NTRS)

1976-01-01

A preliminary identification of the Supporting Research and Technology (SR&T) necessary during the planned evolution of atmospheric cloud physics is discussed. All requirements are for subsequent flights over its expected ten year lifetime. Those components identified as requiring some SR&T work prior to inclusion are listed. A data sheet is included for each item, briefly justifying the need, giving general objectives for the proposed development effort and identifying approximate schedule requirements on the program.

Cloud chamber experiments on the origin of ice crystal complexity in cirrus clouds

NASA Astrophysics Data System (ADS)

Schnaiter, Martin; Järvinen, Emma; Vochezer, Paul; Abdelmonem, Ahmed; Wagner, Robert; Jourdan, Olivier; Mioche, Guillaume; Shcherbakov, Valery N.; Schmitt, Carl G.; Tricoli, Ugo; Ulanowski, Zbigniew; Heymsfield, Andrew J.

2016-04-01

This study reports on the origin of small-scale ice crystal complexity and its influence on the angular light scattering properties of cirrus clouds. Cloud simulation experiments were conducted at the AIDA (Aerosol Interactions and Dynamics in the Atmosphere) cloud chamber of the Karlsruhe Institute of Technology (KIT). A new experimental procedure was applied to grow and sublimate ice particles at defined super- and subsaturated ice conditions and for temperatures in the -40 to -60 °C range. The experiments were performed for ice clouds generated via homogeneous and heterogeneous initial nucleation. Small-scale ice crystal complexity was deduced from measurements of spatially resolved single particle light scattering patterns by the latest version of the Small Ice Detector (SID-3). It was found that a high crystal complexity dominates the microphysics of the simulated clouds and the degree of this complexity is dependent on the available water vapor during the crystal growth. Indications were found that the small-scale crystal complexity is influenced by unfrozen H2SO4 / H2O residuals in the case of homogeneous initial ice nucleation. Angular light scattering functions of the simulated ice clouds were measured by the two currently available airborne polar nephelometers: the polar nephelometer (PN) probe of Laboratoire de Métérologie et Physique (LaMP) and the Particle Habit Imaging and Polar Scattering (PHIPS-HALO) probe of KIT. The measured scattering functions are featureless and flat in the side and backward scattering directions. It was found that these functions have a rather low sensitivity to the small-scale crystal complexity for ice clouds that were grown under typical atmospheric conditions. These results have implications for the microphysical properties of cirrus clouds and for the radiative transfer through these clouds.

Tradeoffs in Acceleration and Initialization of Superparameterized Global Atmospheric Models for MJO and Climate Science

NASA Astrophysics Data System (ADS)

Pritchard, M. S.; Bretherton, C. S.; DeMott, C. A.

2014-12-01

New trade-offs are discussed in the cloud superparameterization approach to explicitly representing deep convection in global climate models. Intrinsic predictability tests show that the memory of cloud-resolving-scale organization is not critical for producing desired modes of organized convection such as the Madden-Julian Oscillation (MJO). This has implications for the feasibility of data assimilation and real-world initialization for superparameterized weather forecasting. Climate simulation sensitivity tests demonstrate that 400% acceleration of cloud superparameterization is possible by restricting the 32-128 km scale regime without deteriorating the realism of the simulated MJO but the number of cloud resolving model grid columns is discovered to constrain the efficiency of vertical mixing, with consequences for the simulated liquid cloud climatology. Tuning opportunities for next generation accelerated superparameterized climate models are discussed.

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

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

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.

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.

Retrieval with Infrared Atmospheric Sounding Interferometer and Validation during JAIVEx

NASA Technical Reports Server (NTRS)

Zhou, Daniel K.; Liu, Xu; Larar, Allen M.; Smith, William L.; Taylor, Jonathan P.; Schluessel, Peter; Strow, L. Larrabee; Mango, Stephen A.

2008-01-01

A state-of-the-art IR-only retrieval algorithm has been developed with an all-season-global EOF Physical Regression and followed by 1-D Var. Physical Iterative Retrieval for IASI, AIRS, and NAST-I. The benefits of this retrieval are to produce atmospheric structure with a single FOV horizontal resolution (approx. 15 km for IASI and AIRS), accurate profiles above the cloud (at least) or down to the surface, surface parameters, and/or cloud microphysical parameters. Initial case study and validation indicates that surface, cloud, and atmospheric structure (include TBL) are well captured by IASI and AIRS measurements. Coincident dropsondes during the IASI and AIRS overpasses are used to validate atmospheric conditions, and accurate retrievals are obtained with an expected vertical resolution. JAIVEx has provided the data needed to validate the retrieval algorithm and its products which allows us to assess the instrument ability and/or performance. Retrievals with global coverage are under investigation for detailed retrieval assessment. It is greatly desired that these products be used for testing the impact on Atmospheric Data Assimilation and/or Numerical Weather Prediction.

CERES cloud property retrievals from imagers on TRMM, Terra, and Aqua

NASA Astrophysics Data System (ADS)

Minnis, Patrick; Young, David F.; Sun-Mack, Sunny; Heck, Patrick W.; Doelling, David R.; Trepte, Qing Z.

2004-02-01

The micro- and macrophysical properties of clouds play a crucial role in Earth"s radiation budget. The NASA Clouds and Earth"s Radiant Energy System (CERES) is providing simultaneous measurements of the radiation and cloud fields on a global basis to improve the understanding and modeling of the interaction between clouds and radiation at the top of the atmosphere, at the surface, and within the atmosphere. Cloud properties derived for CERES from the Moderate Resolution Imaging Spectroradiometer (MODIS) on the Terra and Aqua satellites are compared to ensure consistency between the products to ensure the reliability of the retrievals from multiple platforms at different times of day. Comparisons of cloud fraction, height, optical depth, phase, effective particle size, and ice and liquid water paths from the two satellites show excellent consistency. Initial calibration comparisons are also very favorable. Differences between the Aqua and Terra results are generally due to diurnally dependent changes in the clouds. Additional algorithm refinement is needed over the polar regions for Aqua and at night over those same areas for Terra. The results should be extremely valuable for model validation and improvement and for improving our understanding of the relationship between clouds and the radiation budget.

Isotopic modeling of the sub-cloud evaporation effect in precipitation.

PubMed

Salamalikis, V; Argiriou, A A; Dotsika, E

2016-02-15

In dry and warm environments sub-cloud evaporation influences the falling raindrops modifying their final stable isotopic content. During their descent from the cloud base towards the ground surface, through the unsaturated atmosphere, hydrometeors are subjected to evaporation whereas the kinetic fractionation results to less depleted or enriched isotopic signatures compared to the initial isotopic composition of the raindrops at cloud base. Nowadays the development of Generalized Climate Models (GCMs) that include isotopic content calculation modules are of great interest for the isotopic tracing of the global hydrological cycle. Therefore the accurate description of the underlying processes affecting stable isotopic content can improve the performance of iso-GCMs. The aim of this study is to model the sub-cloud evaporation effect using a) mixing and b) numerical isotope evaporation models. The isotope-mixing evaporation model simulates the isotopic enrichment (difference between the ground and the cloud base isotopic composition of raindrops) in terms of raindrop size, ambient temperature and relative humidity (RH) at ground level. The isotopic enrichment (Δδ) varies linearly with the evaporated raindrops mass fraction of the raindrop resulting to higher values at drier atmospheres and for smaller raindrops. The relationship between Δδ and RH is described by a 'heat capacity' model providing high correlation coefficients for both isotopes (R(2)>80%) indicating that RH is an ideal indicator of the sub-cloud evaporation effect. Vertical distribution of stable isotopes in falling raindrops is also investigated using a numerical isotope-evaporation model. Temperature and humidity dependence of the vertical isotopic variation is clearly described by the numerical isotopic model showing an increase in the isotopic values with increasing temperature and decreasing RH. At an almost saturated atmosphere (RH=95%) sub-cloud evaporation is negligible and the isotopic composition hardly changes even at high temperatures while at drier and warm conditions the enrichment of (18)Ο reaches up to 20‰, depending on the raindrop size and the initial meteorological conditions. Copyright © 2015 Elsevier B.V. All rights reserved.

New GOES-R Risk Reduction Activities at CIRA

NASA Astrophysics Data System (ADS)

Rogers, M. A.; Miller, S. D.; Grasso, L. D.; Haynes, J. M.; NOH, Y. J.; Forsythe, J.; Zupanski, M.; Lindsey, D. T.

2017-12-01

A team of atmospheric scientists at the Cooperative Institute for Research in the Atmosphere (CIRA) at the Colorado State University has been selected by the National Oceanic and Atmospheric Administration's (NOAA) GOES-R Risk Reduction (GOES-R3) science program to develop applications to enhance the utilization of the GOES-R sensors, including the Advanced Baseline Imager (ABI) and the Geostationary Lightning Mapper (GLM). The selected project topics follow NOAA's Research and Development Objectives listed in its 5-year Strategic Plan. The projects will be carried out over a three-year period which started on 1 July 2017 and will end on 30 June 2019. CIRA is working on five GOES-R3 application developments: 1) Developing an Environmental Awareness Repertoire of ABI Imagery (`DEAR-ABII') to Advise the Operational Weather Forecaster. DEAR-ABII maximizes the vast potential of the new GOES-R/GOES-16 sensor technology. 2) GOES-R ABI channel differencing used to reveal cloud-free zones of `precursors of convective initiation'. This product identifies where convective initiation may occur in cloud free skies. 3) Improving the ABI Cloud Layers Product for Multiple Layer Cloud Systems and Aviation Forecast Applications. This project aims to improve the GOES-16 cloud layer product by providing information on the boundaries of cloud layers even when one layer overlies another. 4) Using the New Capabilities of GOES-R to Improve Blended, Multisensor Water Vapor Products for Forecasters. GOES-R TPW retrievals will be merged with TPW derived from polar orbiter and surface data to improve the operational NOAA blended TPW product. 5) Data assimilation of GLM observations in HWRF/GSI system. Assimilation of GOES-R GLM observations for the NOAA operational hurricane model with the goal to improve operational hurricane forecasting. Examples for each of these applications will be presented.

Biogenic Potassium Salt Particles as Seeds for Secondary Organic Aerosol in the Amazon

NASA Astrophysics Data System (ADS)

Pöhlker, Christopher; Wiedemann, Kenia T.; Sinha, Bärbel; Shiraiwa, Manabu; Gunthe, Sachin S.; Smith, Mackenzie; Su, Hang; Artaxo, Paulo; Chen, Qi; Cheng, Yafang; Elbert, Wolfgang; Gilles, Mary K.; Kilcoyne, Arthur L. D.; Moffet, Ryan C.; Weigand, Markus; Martin, Scot T.; Pöschl, Ulrich; Andreae, Meinrat O.

2012-08-01

The fine particles serving as cloud condensation nuclei in pristine Amazonian rainforest air consist mostly of secondary organic aerosol. Their origin is enigmatic, however, because new particle formation in the atmosphere is not observed. Here, we show that the growth of organic aerosol particles can be initiated by potassium-salt-rich particles emitted by biota in the rainforest. These particles act as seeds for the condensation of low- or semi-volatile organic compounds from the atmospheric gas phase or multiphase oxidation of isoprene and terpenes. Our findings suggest that the primary emission of biogenic salt particles directly influences the number concentration of cloud condensation nuclei and affects the microphysics of cloud formation and precipitation over the rainforest.

Chemical Initiation of FAE Clouds

DTIC Science & Technology

1980-11-01

iadlded significant FAE blasts when performed in open air, no blasl when performed in an atmosphere of nitrogen, and a very strong blast when per...miniature experiments produced well-measurable blast pressures which were considerably larger when the ambient atmosphere was air instead of nitrogen, and...very much larger when the ambient atmosphere was oxygen. It was thus demonstrated that the blast wave is reinforced by release of combustion energy

A Cloud Microphysics Model for the Gas Giant Planets

NASA Astrophysics Data System (ADS)

Palotai, Csaba J.; Le Beau, Raymond P.; Shankar, Ramanakumar; Flom, Abigail; Lashley, Jacob; McCabe, Tyler

2016-10-01

Recent studies have significantly increased the quality and the number of observed meteorological features on the jovian planets, revealing banded cloud structures and discrete features. Our current understanding of the formation and decay of those clouds also defines the conceptual modes about the underlying atmospheric dynamics. The full interpretation of the new observational data set and the related theories requires modeling these features in a general circulation model (GCM). Here, we present details of our bulk cloud microphysics model that was designed to simulate clouds in the Explicit Planetary Hybrid-Isentropic Coordinate (EPIC) GCM for the jovian planets. The cloud module includes hydrological cycles for each condensable species that consist of interactive vapor, cloud and precipitation phases and it also accounts for latent heating and cooling throughout the transfer processes (Palotai and Dowling, 2008. Icarus, 194, 303-326). Previously, the self-organizing clouds in our simulations successfully reproduced the vertical and horizontal ammonia cloud structure in the vicinity of Jupiter's Great Red Spot and Oval BA (Palotai et al. 2014, Icarus, 232, 141-156). In our recent work, we extended this model to include water clouds on Jupiter and Saturn, ammonia clouds on Saturn, and methane clouds on Uranus and Neptune. Details of our cloud parameterization scheme, our initial results and their comparison with observations will be shown. The latest version of EPIC model is available as open source software from NASA's PDS Atmospheres Node.

Multi-Spectral Cloud Retrievals from Moderate Image Spectrometer (MODIS)

NASA Technical Reports Server (NTRS)

Platnick, Steven

2004-01-01

MODIS observations from the NASA EOS Terra spacecraft (1030 local time equatorial sun-synchronous crossing) launched in December 1999 have provided a unique set of Earth observation data. With the launch of the NASA EOS Aqua spacecraft (1330 local time crossing! in May 2002: two MODIS daytime (sunlit) and nighttime observations are now available in a 24-hour period allowing some measure of diurnal variability. A comprehensive set of remote sensing algorithms for cloud masking and the retrieval of cloud physical and optical properties has been developed by members of the MODIS atmosphere science team. The archived products from these algorithms have applications in climate modeling, climate change studies, numerical weather prediction, as well as fundamental atmospheric research. In addition to an extensive cloud mask, products include cloud-top properties (temperature, pressure, effective emissivity), cloud thermodynamic phase, cloud optical and microphysical parameters (optical thickness, effective particle radius, water path), as well as derived statistics. An overview of the instrument and cloud algorithms will be presented along with various examples, including an initial analysis of several operational global gridded (Level-3) cloud products from the two platforms. Statistics of cloud optical and microphysical properties as a function of latitude for land and Ocean regions will be shown. Current algorithm research efforts will also be discussed.

Ionization in atmospheres of brown dwarfs and extrasolar planets VI: Properties of large-scale discharge events

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bailey, R. L.; Helling, Ch.; Hodosán, G.

2014-03-20

Mineral clouds in substellar atmospheres play a special role as a catalyst for a variety of charge processes. If clouds are charged, the surrounding environment becomes electrically activated, and ensembles of charged grains are electrically discharging (e.g., by lightning), which significantly influences the local chemistry creating conditions similar to those thought responsible for life in early planetary atmospheres. We note that such lightning discharges contribute also to the ionization state of the atmosphere. We apply scaling laws for electrical discharge processes from laboratory measurements and numerical experiments to DRIFT-PHOENIX model atmosphere results to model the discharge's propagation downward (as lightning)more » and upward (as sprites) through the atmospheric clouds. We evaluate the spatial extent and energetics of lightning discharges. The atmospheric volume affected (e.g., by increase of temperature or electron number) is larger in a brown dwarf atmosphere (10{sup 8}-10{sup 10} m{sup 3}) than in a giant gas planet (10{sup 4}-10{sup 6} m{sup 3}). Our results suggest that the total dissipated energy in one event is <10{sup 12} J for all models of initial solar metallicity. First attempts to show the influence of lightning on the local gas phase indicate an increase of small carbohydrate molecules like CH and CH{sub 2} at the expense of CO and CH{sub 4}. Dust-forming molecules are destroyed and the cloud particle properties are frozen in unless enough time is available for complete evaporation. We summarize instruments potentially suitable to observe lightning on extrasolar objects.« less

Techniques and resources for storm-scale numerical weather prediction

NASA Technical Reports Server (NTRS)

Droegemeier, Kelvin; Grell, Georg; Doyle, James; Soong, Su-Tzai; Skamarock, William; Bacon, David; Staniforth, Andrew; Crook, Andrew; Wilhelmson, Robert

1993-01-01

The topics discussed include the following: multiscale application of the 5th-generation PSU/NCAR mesoscale model, the coupling of nonhydrostatic atmospheric and hydrostatic ocean models for air-sea interaction studies; a numerical simulation of cloud formation over complex topography; adaptive grid simulations of convection; an unstructured grid, nonhydrostatic meso/cloud scale model; efficient mesoscale modeling for multiple scales using variable resolution; initialization of cloud-scale models with Doppler radar data; and making effective use of future computing architectures, networks, and visualization software.

Global transport of atmospheric smoke following a major nuclear exchange

NASA Technical Reports Server (NTRS)

Haberle, R. M.; Ackerman, T. P.; Toon, O. B.; Hollingsworth, J. L.

1985-01-01

A fully interactive zonally symmetric general circulation model is used to simulate the transport and evolution of a massive smoke cloud that is likely to form in the atmosphere following a major nuclear war. The presence of such a cloud significantly alters the simulated circulation and the subsequent transport of the smoke particles themselves. While the model indicates a tendency for interhemispheric exchange, the most immediate effect is that the radiatively active particles are carried into the stratosphere by the generation of strong vertical motions and intense convection regardless of their initial injection altitudes.

Global transport of atmospheric smoke following a major nuclear exchange

NASA Astrophysics Data System (ADS)

Haberle, Robert M.; Ackerman, Thomas P.; Toon, Owen B.; Hollingsworth, Jeffery L.

A fully interactive zonally symmetric general circulation model is used to simulate the transport and evolution of a massive smoke cloud that is likely to form in the atmosphere following a major nuclear war. The presence of such a cloud significantly alters the simulated circulation and the subsequent transport of the smoke particles themselves. While the model indicates a tendency for interhemispheric exchange, the most immediate effect is that the radiatively active particles are carried into the stratosphere by the generation of strong vertical motions and intense convection regardless of their initial injection altitudes.

Satellite-Surface Perspectives of Air Quality and Aerosol-Cloud Effects on the Environment: An Overview of 7-SEAS BASELInE

NASA Technical Reports Server (NTRS)

Tsay, Si-Chee; Maring, Hal B.; Lin, Neng-Huei; Buntoung, Sumaman; Chantara, Somporn; Chuang, Hsiao-Chi; Gabriel, Philip M.; Goodloe, Colby S.; Holben, Brent N.; Hsiao, Ta-Chih;

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

NASA Technical Reports Server (NTRS)

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

2001-01-01

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

Thermodynamics in the Suppressed Phase of the Madden-Julian Oscillation Using a Multiplatform Strategy

NASA Technical Reports Server (NTRS)

Roberts, J. Brent; Robertson, Franklin R.; Clayson, Carol Anne; Taylor, Patrick

2014-01-01

The Madden-Julian Oscillation (MJO) represents a prominent mode of intraseasonal tropical variability. It is manifest by coherent large-scale changes in atmospheric circulation, convection, and thermodynamic processes. Preconditioning of the environment prior to the active phase of the MJO has been noted, but the balance of theorized mechanisms to accomplish this process remains unresolved. Further, there is a lack of consensus on the means by which primary initiation of an MJO event occurs. Observational and modeling efforts have recently been undertaken to advance our understanding of the physical underpinnings governing MJO development. However these intensive studies are often limited in space and/or time and are potentially subject to model deficiencies. Satellite observations, especially those providing vertical resolution of temperature and moisture, provide an opportunity to expand our knowledge of processes critical to MJO initiation and preconditioning. This work will provide an analysis of suppressed phase thermodynamics with an emphasis on the use of a complementary suite of satellite observations including AIRS/AMSU-A profiles, CERES radiative fluxes, and cloud properties observed by MODIS. Emphasis of this work will regard the distribution of cloud regimes, their radiative-convective effects, and their relationship to moist static energy during the recharge and suppressed stages of MJO initiation and eastward propagation. The analyses will make use of cloud regimes from MODIS observations to provide a compositing technique that enables the identification of systematic connections between different cloud regimes and the larger scale environment. Within these cloud regimes, the relationship between the associated cloud-radiative effects observed by CERES, vertically-resolved and vertically-integrated thermodynamics using AIRS/AMSU-A observations, and atmospheric boundary layer fluxes will be demonstrated.

Atmospheric Collapse on Early Mars: The Role of CO2 Clouds

NASA Technical Reports Server (NTRS)

Kahre, M. A.; Haberle, R. M.; Steakley, K. E.; Murphy, J. R.; Kling, A.

2017-01-01

The abundance of evidence that liquid water flowed on the surface early in Mars' history strongly implies that the early Martian atmosphere was significantly more massive than it is today. While it seems clear that the total CO2 inventory was likely substantially larger in the past, the fundamental question about the physical state of that CO2 is not completely understood. Because the temperature at which CO2 condenses increases with surface pressure, surface CO2 ice is more likely to form and persist as the atmospheric mass increases. For the atmosphere to remain stable against collapse, there must be enough energy, distributed planet wide, to stave off the formation of permanent CO2 caps that leads to atmospheric collapse. The presence of a "faint young sun" that was likely about 25 percent less luminous 3.8 billion years ago than the sun today makes this even more difficult. Several physical processes play a role in the ultimate stability of a CO2 atmosphere. The system is regulated by the energy balance between solar insolation, the radiative effects of the atmosphere and its constituents, atmospheric heat transport, heat exchange between the surface and the atmosphere, and latent heating/cooling. Specific considerations in this balance for a given orbital obliquity/eccentricity and atmospheric mass are the albedo of the caps, the dust content of the atmosphere, and the presence of water and/or CO2 clouds. Forget et al. show that, for Mars' current obliquity (in a circular orbit), CO2 atmospheres ranging in surface pressure from 500 hectopascals to 3000 hectopascals would have been stable against collapsing into permanent surface ice reservoirs. Soto et al. examined a similar range in initial surface pressure to investigate atmospheric collapse and to compute collapse rates. CO2 clouds and their radiative effects were included in Forget et al. but they were not included in Soto et al. Here we focus on how CO2 clouds affect the stability of the atmosphere against collapse.

Production of extremely low volatile organic compounds from biogenic emissions: Measured yields and atmospheric implications

PubMed Central

Jokinen, Tuija; Berndt, Torsten; Makkonen, Risto; Kerminen, Veli-Matti; Junninen, Heikki; Stratmann, Frank; Herrmann, Hartmut; Guenther, Alex B.; Worsnop, Douglas R.; Kulmala, Markku; Ehn, Mikael; Sipilä, Mikko

2015-01-01

Oxidation products of monoterpenes and isoprene have a major influence on the global secondary organic aerosol (SOA) burden and the production of atmospheric nanoparticles and cloud condensation nuclei (CCN). Here, we investigate the formation of extremely low volatility organic compounds (ELVOC) from O3 and OH radical oxidation of several monoterpenes and isoprene in a series of laboratory experiments. We show that ELVOC from all precursors are formed within the first minute after the initial attack of an oxidant. We demonstrate that under atmospherically relevant concentrations, species with an endocyclic double bond efficiently produce ELVOC from ozonolysis, whereas the yields from OH radical-initiated reactions are smaller. If the double bond is exocyclic or the compound itself is acyclic, ozonolysis produces less ELVOC and the role of the OH radical-initiated ELVOC formation is increased. Isoprene oxidation produces marginal quantities of ELVOC regardless of the oxidant. Implementing our laboratory findings into a global modeling framework shows that biogenic SOA formation in general, and ELVOC in particular, play crucial roles in atmospheric CCN production. Monoterpene oxidation products enhance atmospheric new particle formation and growth in most continental regions, thereby increasing CCN concentrations, especially at high values of cloud supersaturation. Isoprene-derived SOA tends to suppress atmospheric new particle formation, yet it assists the growth of sub-CCN-size primary particles to CCN. Taking into account compound specific monoterpene emissions has a moderate effect on the modeled global CCN budget. PMID:26015574

Production of extremely low volatile organic compounds from biogenic emissions: Measured yields and atmospheric implications.

PubMed

Jokinen, Tuija; Berndt, Torsten; Makkonen, Risto; Kerminen, Veli-Matti; Junninen, Heikki; Paasonen, Pauli; Stratmann, Frank; Herrmann, Hartmut; Guenther, Alex B; Worsnop, Douglas R; Kulmala, Markku; Ehn, Mikael; Sipilä, Mikko

2015-06-09

Oxidation products of monoterpenes and isoprene have a major influence on the global secondary organic aerosol (SOA) burden and the production of atmospheric nanoparticles and cloud condensation nuclei (CCN). Here, we investigate the formation of extremely low volatility organic compounds (ELVOC) from O3 and OH radical oxidation of several monoterpenes and isoprene in a series of laboratory experiments. We show that ELVOC from all precursors are formed within the first minute after the initial attack of an oxidant. We demonstrate that under atmospherically relevant concentrations, species with an endocyclic double bond efficiently produce ELVOC from ozonolysis, whereas the yields from OH radical-initiated reactions are smaller. If the double bond is exocyclic or the compound itself is acyclic, ozonolysis produces less ELVOC and the role of the OH radical-initiated ELVOC formation is increased. Isoprene oxidation produces marginal quantities of ELVOC regardless of the oxidant. Implementing our laboratory findings into a global modeling framework shows that biogenic SOA formation in general, and ELVOC in particular, play crucial roles in atmospheric CCN production. Monoterpene oxidation products enhance atmospheric new particle formation and growth in most continental regions, thereby increasing CCN concentrations, especially at high values of cloud supersaturation. Isoprene-derived SOA tends to suppress atmospheric new particle formation, yet it assists the growth of sub-CCN-size primary particles to CCN. Taking into account compound specific monoterpene emissions has a moderate effect on the modeled global CCN budget.

Modeling Studying the Role of Bacteria on ice Nucleation Processes

NASA Astrophysics Data System (ADS)

Sun, J.

2006-12-01

Certain air-borne bacteria have been recognized as active ice nuclei at the temperatures warm than - 10°C. Ice nucleating bacteria commonly found in plants and ocean surface. These ice nucleating bacteria are readily disseminated into the atmosphere and have been observed in clouds and hailstones, and their importance in cloud formation process and precipitation, as well as causing diseases in plants and animal kingdom, have been considered for over two decades, but their significance in atmospheric processes are yet to be understood. A 1.5-D non-hydrostatic cumulus cloud model with bin-resolved microphysics is developed and is to used to examine the relative importance of sulphate aerosol concentrations on the evolution of cumulus cloud droplet spectra and ice multiplication process, as well as ice initiation process by ice nucleating bacteria in the growing stage of cumulus clouds and the key role of this process on the ice multiplication in the subsequent dissipating stage of cumulus clouds. In this paper, we will present some sensitivity test results of the evolution of cumulus cloud spectra, ice concentrations at various concentrations of sulfate aerosols, and at different ideal sounding profiles. We will discuss the implication of our results in understanding of ice nucleation processes.

Towards a new parameterization of ice particles growth

NASA Astrophysics Data System (ADS)

Krakovska, Svitlana; Khotyayintsev, Volodymyr; Bardakov, Roman; Shpyg, Vitaliy

2017-04-01

Ice particles are the main component of polar clouds, unlike in warmer regions. That is why correct representation of ice particle formation and growth in NWP and other numerical atmospheric models is crucial for understanding of the whole chain of water transformation, including precipitation formation and its further deposition as snow in polar glaciers. Currently, parameterization of ice in atmospheric models is among the most difficult challenges. In the presented research, we present a renewed theoretical analysis of the evolution of mixed cloud or cold fog from the moment of ice nuclei activation until complete crystallization. The simplified model is proposed that includes both supercooled cloud droplets and initially uniform particles of ice, as well as water vapor. We obtain independent dimensionless input parameters of a cloud, and find main scenarios and stages of evolution of the microphysical state of the cloud. The characteristic times and particle sizes have been found, as well as the peculiarities of microphysical processes at each stage of evolution. In the future, the proposed original and physically grounded approximations may serve as a basis for a new scientifically substantiated and numerically efficient parameterizations of microphysical processes in mixed clouds for modern atmospheric models. The relevance of theoretical analysis is confirmed by numerical modeling for a wide range of combinations of possible conditions in the atmosphere, including cold polar regions. The main conclusion of the research is that until complete disappearance of cloud droplets, the growth of ice particles occurs at a practically constant humidity corresponding to the saturated humidity over water, regardless to all other parameters of a cloud. This process can be described by the one differential equation of the first order. Moreover, a dimensionless parameter has been proposed as a quantitative criterion of a transition from dominant depositional to intense collectional growth of ice particles; it could be used in models with bulk parameterization of cloud and precipitation formation processes.

The clouds of Venus. II - An investigation of the influence of coagulation on the observed droplet size distribution

NASA Technical Reports Server (NTRS)

Rossow, W. B.

1977-01-01

An approximate numerical technique is used to investigate the influence of coagulation, sedimentation and turbulent motions on the observed droplet size distribution in the upper layers of the Venus clouds. If the cloud mass mixing ratio is less than 0.000001 at 250 K or the eddy diffusivity throughout the cloud is greater than 1,000,000 sq cm per sec, then coagulation is unimportant. In this case, the observed droplet size distribution is the initial size distribution produced by the condensation of the droplets. It is found that all cloud models with droplet formation near the cloud top (e.g., a photochemical model) must produce the observed droplet size distribution by condensation without subsequent modification by coagulation. However, neither meteoritic or surface dust can supply sufficient nucleating particles to account for the observed droplet number density. If the cloud droplets are formed near the cloud bottom, the observed droplet size distribution can be produced solely by the interaction of coagulation and dynamics; all information about the initial size distribution is lost. If droplet formation occurs near the cloud bottom, the lower atmosphere of Venus is oxidizing rather than reducing.

IPRT polarized radiative transfer model intercomparison project - Three-dimensional test cases (phase B)

NASA Astrophysics Data System (ADS)

Emde, Claudia; Barlakas, Vasileios; Cornet, Céline; Evans, Frank; Wang, Zhen; Labonotte, Laurent C.; Macke, Andreas; Mayer, Bernhard; Wendisch, Manfred

2018-04-01

Initially unpolarized solar radiation becomes polarized by scattering in the Earth's atmosphere. In particular molecular scattering (Rayleigh scattering) polarizes electromagnetic radiation, but also scattering of radiation at aerosols, cloud droplets (Mie scattering) and ice crystals polarizes. Each atmospheric constituent produces a characteristic polarization signal, thus spectro-polarimetric measurements are frequently employed for remote sensing of aerosol and cloud properties. Retrieval algorithms require efficient radiative transfer models. Usually, these apply the plane-parallel approximation (PPA), assuming that the atmosphere consists of horizontally homogeneous layers. This allows to solve the vector radiative transfer equation (VRTE) efficiently. For remote sensing applications, the radiance is considered constant over the instantaneous field-of-view of the instrument and each sensor element is treated independently in plane-parallel approximation, neglecting horizontal radiation transport between adjacent pixels (Independent Pixel Approximation, IPA). In order to estimate the errors due to the IPA approximation, three-dimensional (3D) vector radiative transfer models are required. So far, only a few such models exist. Therefore, the International Polarized Radiative Transfer (IPRT) working group of the International Radiation Commission (IRC) has initiated a model intercomparison project in order to provide benchmark results for polarized radiative transfer. The group has already performed an intercomparison for one-dimensional (1D) multi-layer test cases [phase A, 1]. This paper presents the continuation of the intercomparison project (phase B) for 2D and 3D test cases: a step cloud, a cubic cloud, and a more realistic scenario including a 3D cloud field generated by a Large Eddy Simulation (LES) model and typical background aerosols. The commonly established benchmark results for 3D polarized radiative transfer are available at the IPRT website (http://www.meteo.physik.uni-muenchen.de/ iprt).

Soil Moisture, Coastline Curvature, and Sea Breeze Initiated Precipitation Over Florida

NASA Technical Reports Server (NTRS)

Baker, R. David; Lynn, Barry H.; Boone, Aaron; Tao, Wei-Kuo

1999-01-01

Land surface-atmosphere interaction plays a key role in the development of summertime convection and precipitation over the Florida peninsula. Land-ocean temperature contrasts induce sea-breeze circulations along both coasts. Clouds develop along sea-breeze fronts, and significant precipitation can occur during the summer months. However, other factors such as soil moisture distribution and coastline curvature may modulate the timing, location, and intensity of sea breeze initiated precipitation. Here, we investigate the role of soil moisture and coastline curvature on Florida precipitation using the 3-D Goddard Cumulus Ensemble (GCE) cloud model coupled with the Parameterization for Land-Atmosphere-Cloud Exchange (PLACE) land surface model. This study utilizes data from the Convection and Precipitation Electrification Experiment (CaPE) collected on 27 July 1991. Our numerical simulations suggest that a realistic distribution of soil moisture influences the location and intensity of precipitation but not the timing of precipitation. In contrast, coastline curvature affects the timing and location of precipitation but has little influence on peak rainfall rates. However, both factors (soil moisture and coastline curvature) are required to fully account for observed rainfall amounts.

On the Spatial Power Spectrum of the E x B Gradient Drift Instability in Ionospheric Plasma Clouds.

DTIC Science & Technology

1981-04-14

Perkins et al., 1973]. In reality, an artificially injected plasma cloud will, initially, be two- dimensional in the plane perpendicular to the magnetic...Motion of Artificial Ion Clouds in the Upper Atmosphere, Planet. Space Sci., 15, 1, 1967. Kelley, M.C., K.D. Baker, and J.C. Ulwick, Late Time Barium...42960 COMiANDER WORLOA’AY POS’AL CENTER J.S. ARMY MISSILE INTELLIGENCE AGENCY "’OS ANGELES, CA. 90009 REDSTONE ARSENAL, AL 35809 OICY ATTN CODE 52 0ICY

A cloud and radiation model-based algorithm for rainfall retrieval from SSM/I multispectral microwave measurements

NASA Technical Reports Server (NTRS)

Xiang, Xuwu; Smith, Eric A.; Tripoli, Gregory J.

1992-01-01

A hybrid statistical-physical retrieval scheme is explored which combines a statistical approach with an approach based on the development of cloud-radiation models designed to simulate precipitating atmospheres. The algorithm employs the detailed microphysical information from a cloud model as input to a radiative transfer model which generates a cloud-radiation model database. Statistical procedures are then invoked to objectively generate an initial guess composite profile data set from the database. The retrieval algorithm has been tested for a tropical typhoon case using Special Sensor Microwave/Imager (SSM/I) data and has shown satisfactory results.

Atmospheric Dispersion of Hypergolic Liquid Rocket Fuels. Volume 2

DTIC Science & Technology

1984-11-01

time tI required for the initial concentration of nitr- gen dioxide [NO 2]0 to decay to I ppm yields the expression [NO2 ]O - I ppm t - ( 2 (3-16)k3 [H2[0...19S1 ACCIDENT TINE IS 1015 EST 12 NOV 1931 TINE OF EXECUTION IS 2140 EST 9 PFE 1984 PEAK CLOUD CLOUD fANCE IEANING CONCEN- ARRIVAL 01PAITOOE FROM SITE

A-Train Education Activities: Partnerships to Engage Citizens with Atmospheric Science

NASA Astrophysics Data System (ADS)

Ellis, T. D.; Taylor, J.; Chambers, L. H.; Graham, S.; Butcher, G. J.

2016-12-01

Since the launch of Aqua in 2002, the A-Train satellites have been at the forefront of observing Earth's atmosphere using the wide variety of instruments on the spacecraft in the formation. Similarly, the A-Train missions have also taken a variety of perspectives on engaging the general public with NASA science. These approaches have included a range of formal education partnerships featuring the GLOBE program (including a cloud observation network through CloudSat, several initiatives to understand and measure aerosols, and development of a new elementary story book), unique citizen-science activities such as Students' Cloud Observations On Line (S'COOL), connections with the PBS Kids SciGirls program, and much more. An education component was also featured at the first A-Train symposium in New Orleans, engaging local educators to learn about the many education resources available from the A-Train missions. Increasingly, the mission education teams have been working together to drive home thematic science content, such as the roles of clouds in our climate system and regular measurements of Earth's radiant energy balance. This paper describes the evolution of A-Train education efforts over the past decade, highlights key achievements, and presents information on new initiatives to continue to engage the public with A-Train science.

The initial giant umbrella cloud of the May 18th, 1980, explosive eruption of Mount St. Helens

USGS Publications Warehouse

Sparks, R.S.J.; Moore, J.G.; Rice, C.J.

1986-01-01

The initial eruption column of May 18th, 1980 reached nearly 30 km altitude and released 1017 joules of thermal energy into the atmosphere in only a few minutes. Ascent of the cloud resulted in forced intrusion of a giant umbrella-shaped cloud between altitudes of 10 and 20 km at radial horizontal velocities initially in excess of 50 m/s. The mushroom cloud expanded 15 km upwind, forming a stagnation point where the radial expansion velocity and wind velocity were equal. The cloud was initiated when the pyroclastic blast flow became buoyant. The flow reduced its density as it moved away from the volcano by decompression, by sedimentation, and by mixing with and heating the surrounding air. Observations indicate that much of the flow, covering an area of 600 km2, became buoyant within 1.5 minutes and abruptly ascended to form the giant cloud. Calculations are presented for the amount of air that must have been entrained into the flow to make it buoyant. Assuming an initial temperature of 450??C and a magmatic origin for the explosion, these calculations indicate that the flow became buoyant when its temperature was approximately 150??C and the flow consisted of a mixture of 3.25 ?? 1011 kg of pyroclasts and 5.0 ?? 1011 kg of air. If sedimentation is considered, these figures reduce to 1.1 ?? 1011 kg of pyroclasts and 1.0 ?? 1011 kg of air. ?? 1986.

A global cloud map of the nearest known brown dwarf.

PubMed

Crossfield, I J M; Biller, B; Schlieder, J E; Deacon, N R; Bonnefoy, M; Homeier, D; Allard, F; Buenzli, E; Henning, Th; Brandner, W; Goldman, B; Kopytova, T

2014-01-30

Brown dwarfs--substellar bodies more massive than planets but not massive enough to initiate the sustained hydrogen fusion that powers self-luminous stars--are born hot and slowly cool as they age. As they cool below about 2,300 kelvin, liquid or crystalline particles composed of calcium aluminates, silicates and iron condense into atmospheric 'dust', which disappears at still cooler temperatures (around 1,300 kelvin). Models to explain this dust dispersal include both an abrupt sinking of the entire cloud deck into the deep, unobservable atmosphere and breakup of the cloud into scattered patches (as seen on Jupiter and Saturn). However, hitherto observations of brown dwarfs have been limited to globally integrated measurements, which can reveal surface inhomogeneities but cannot unambiguously resolve surface features. Here we report a two-dimensional map of a brown dwarf's surface that allows identification of large-scale bright and dark features, indicative of patchy clouds. Monitoring suggests that the characteristic timescale for the evolution of global weather patterns is approximately one day.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Newsom, R. K.; Sivaraman, C.; Shippert, T. R.

Accurate height-resolved measurements of higher-order statistical moments of vertical velocity fluctuations are crucial for improved understanding of turbulent mixing and diffusion, convective initiation, and cloud life cycles. The Atmospheric Radiation Measurement (ARM) Climate Research Facility operates coherent Doppler lidar systems at several sites around the globe. These instruments provide measurements of clear-air vertical velocity profiles in the lower troposphere with a nominal temporal resolution of 1 sec and height resolution of 30 m. The purpose of the Doppler lidar vertical velocity statistics (DLWSTATS) value-added product (VAP) is to produce height- and time-resolved estimates of vertical velocity variance, skewness, and kurtosismore » from these raw measurements. The VAP also produces estimates of cloud properties, including cloud-base height (CBH), cloud frequency, cloud-base vertical velocity, and cloud-base updraft fraction.« less

An Automatic Cloud Mask Algorithm Based on Time Series of MODIS Measurements

NASA Technical Reports Server (NTRS)

Lyapustin, Alexei; Wang, Yujie; Frey, R.

2008-01-01

Quality of aerosol retrievals and atmospheric correction depends strongly on accuracy of the cloud mask (CM) algorithm. The heritage CM algorithms developed for AVHRR and MODIS use the latest sensor measurements of spectral reflectance and brightness temperature and perform processing at the pixel level. The algorithms are threshold-based and empirically tuned. They don't explicitly address the classical problem of cloud search, wherein the baseline clear-skies scene is defined for comparison. Here, we report on a new CM algorithm which explicitly builds and maintains a reference clear-skies image of the surface (refcm) using a time series of MODIS measurements. The new algorithm, developed as part of the Multi-Angle Implementation of Atmospheric Correction (MAIAC) algorithm for MODIS, relies on fact that clear-skies images of the same surface area have a common textural pattern, defined by the surface topography, boundaries of rivers and lakes, distribution of soils and vegetation etc. This pattern changes slowly given the daily rate of global Earth observations, whereas clouds introduce high-frequency random disturbances. Under clear skies, consecutive gridded images of the same surface area have a high covariance, whereas in presence of clouds covariance is usually low. This idea is central to initialization of refcm which is used to derive cloud mask in combination with spectral and brightness temperature tests. The refcm is continuously updated with the latest clear-skies MODIS measurements, thus adapting to seasonal and rapid surface changes. The algorithm is enhanced by an internal dynamic land-water-snow classification coupled with a surface change mask. An initial comparison shows that the new algorithm offers the potential to perform better than the MODIS MOD35 cloud mask in situations where the land surface is changing rapidly, and over Earth regions covered by snow and ice.

Low clouds suppress Arctic air formation and amplify high-latitude continental winter warming.

PubMed

Cronin, Timothy W; Tziperman, Eli

2015-09-15

High-latitude continents have warmed much more rapidly in recent decades than the rest of the globe, especially in winter, and the maintenance of warm, frost-free conditions in continental interiors in winter has been a long-standing problem of past equable climates. We use an idealized single-column atmospheric model across a range of conditions to study the polar night process of air mass transformation from high-latitude maritime air, with a prescribed initial temperature profile, to much colder high-latitude continental air. We find that a low-cloud feedback--consisting of a robust increase in the duration of optically thick liquid clouds with warming of the initial state--slows radiative cooling of the surface and amplifies continental warming. This low-cloud feedback increases the continental surface air temperature by roughly two degrees for each degree increase of the initial maritime surface air temperature, effectively suppressing Arctic air formation. The time it takes for the surface air temperature to drop below freezing increases nonlinearly to ∼ 10 d for initial maritime surface air temperatures of 20 °C. These results, supplemented by an analysis of Coupled Model Intercomparison Project phase 5 climate model runs that shows large increases in cloud water path and surface cloud longwave forcing in warmer climates, suggest that the "lapse rate feedback" in simulations of anthropogenic climate change may be related to the influence of low clouds on the stratification of the lower troposphere. The results also indicate that optically thick stratus cloud decks could help to maintain frost-free winter continental interiors in equable climates.

Low clouds suppress Arctic air formation and amplify high-latitude continental winter warming

PubMed Central

Cronin, Timothy W.; Tziperman, Eli

2015-01-01

High-latitude continents have warmed much more rapidly in recent decades than the rest of the globe, especially in winter, and the maintenance of warm, frost-free conditions in continental interiors in winter has been a long-standing problem of past equable climates. We use an idealized single-column atmospheric model across a range of conditions to study the polar night process of air mass transformation from high-latitude maritime air, with a prescribed initial temperature profile, to much colder high-latitude continental air. We find that a low-cloud feedback—consisting of a robust increase in the duration of optically thick liquid clouds with warming of the initial state—slows radiative cooling of the surface and amplifies continental warming. This low-cloud feedback increases the continental surface air temperature by roughly two degrees for each degree increase of the initial maritime surface air temperature, effectively suppressing Arctic air formation. The time it takes for the surface air temperature to drop below freezing increases nonlinearly to ∼10 d for initial maritime surface air temperatures of 20 °C. These results, supplemented by an analysis of Coupled Model Intercomparison Project phase 5 climate model runs that shows large increases in cloud water path and surface cloud longwave forcing in warmer climates, suggest that the “lapse rate feedback” in simulations of anthropogenic climate change may be related to the influence of low clouds on the stratification of the lower troposphere. The results also indicate that optically thick stratus cloud decks could help to maintain frost-free winter continental interiors in equable climates. PMID:26324919

Cloud Effects on Meridional Atmospheric Energy Budget Estimated from Clouds and the Earth's Radiant Energy System (CERES) Data

NASA Technical Reports Server (NTRS)

Kato, Seiji; Rose, Fred G.; Rutan, David A.; Charlock, Thomas P.

2008-01-01

The zonal mean atmospheric cloud radiative effect, defined as the difference of the top-of-atmosphere (TOA) and surface cloud radiative effects, is estimated from three years of Clouds and the Earth's Radiant Energy System (CERES) data. The zonal mean shortwave effect is small, though it tends to be positive (warming). This indicates that clouds increase shortwave absorption in the atmosphere, especially in midlatitudes. The zonal mean atmospheric cloud radiative effect is, however, dominated by the longwave effect. The zonal mean longwave effect is positive in the tropics and decreases with latitude to negative values (cooling) in polar regions. The meridional gradient of cloud effect between midlatitude and polar regions exists even when uncertainties in the cloud effect on the surface enthalpy flux and in the modeled irradiances are taken into account. This indicates that clouds increase the rate of generation of mean zonal available potential energy. Because the atmospheric cooling effect in polar regions is predominately caused by low level clouds, which tend to be stationary, we postulate that the meridional and vertical gradients of cloud effect increase the rate of meridional energy transport by dynamics in the atmosphere from midlatitude to polar region, especially in fall and winter. Clouds then warm the surface in polar regions except in the Arctic in summer. Clouds, therefore, contribute in increasing the rate of meridional energy transport from midlatitude to polar regions through the atmosphere.

Electrification of precipitating systems over the Amazon: Physical processes of thunderstorm development

NASA Astrophysics Data System (ADS)

Albrecht, Rachel I.; Morales, Carlos A.; Silva Dias, Maria A. F.

2011-04-01

This study investigated the physical processes involved in the development of thunderstorms over southwestern Amazon by hypothesizing causalities for the observed cloud-to-ground lightning variability and the local environmental characteristics. Southwestern Amazon experiences every year a large variety of environmental factors, such as the gradual increase in atmospheric moisture, extremely high pollution due to biomass burning, and intense deforestation, which directly affects cloud development by differential surface energy partition. In the end of the dry period it was observed higher percentages of positive cloud-to-ground (+CG) lightning due to a relative increase in +CG dominated thunderstorms (positive thunderstorms). Positive (negative) thunderstorms initiated preferentially over deforested (forest) areas with higher (lower) cloud base heights, shallower (deeper) warm cloud depths, and higher (lower) convective potential available energy. These features characterized the positive (negative) thunderstorms as deeper (relatively shallower) clouds, stronger (relatively weaker) updrafts with enhanced (decreased) mixed and cold vertically integrated liquid. No significant difference between thunderstorms (negative and positive) and nonthunderstorms were observed in terms of atmospheric pollution, once the atmosphere was overwhelmed by pollution leading to an updraft-limited regime. However, in the wet season both negative and positive thunderstorms occurred during periods of relatively higher aerosol concentration and differentiated size distributions, suggesting an aerosol-limited regime where cloud electrification could be dependent on the aerosol concentration to suppress the warm and enhance the ice phase. The suggested causalities are consistent with the invoked hypotheses, but they are not observed facts; they are just hypotheses based on plausible physical mechanisms.

Computer image processing of up-draft flow motion and severe storm formation observed from satellite

NASA Technical Reports Server (NTRS)

Hung, R. J.; Smith, R. E.

1985-01-01

Special rapid-scan satellite visible and infrared observations have been used to study the life cycle of the clouds from the initiation of updraft flow motion in the atmosphere, the condensation of humid air, the formation of clouds, the development of towering cumulus, the penetration of the tropopause, the collapsing of an overshooting turret, and the dissipation of cloud. The infrared image provides an indication of the equivalent blackbody temperature of the observed cloud tops. By referencing the temperature, height and humidity profiles from rawinsonde observations as the background meteorological data for the instability of the air mass to the satellite infrared data sets at different time periods, the development of convective clouds can be studied in detail.

The physics of lightning

NASA Astrophysics Data System (ADS)

Dwyer, Joseph R.; Uman, Martin A.

2014-01-01

Despite being one of the most familiar and widely recognized natural phenomena, lightning remains relatively poorly understood. Even the most basic questions of how lightning is initiated inside thunderclouds and how it then propagates for many tens of kilometers have only begun to be addressed. In the past, progress was hampered by the unpredictable and transient nature of lightning and the difficulties in making direct measurements inside thunderstorms, but advances in instrumentation, remote sensing methods, and rocket-triggered lightning experiments are now providing new insights into the physics of lightning. Furthermore, the recent discoveries of intense bursts of X-rays and gamma-rays associated with thunderstorms and lightning illustrate that new and interesting physics is still being discovered in our atmosphere. The study of lightning and related phenomena involves the synthesis of many branches of physics, from atmospheric physics to plasma physics to quantum electrodynamics, and provides a plethora of challenging unsolved problems. In this review, we provide an introduction to the physics of lightning with the goal of providing interested researchers a useful resource for starting work in this fascinating field. By what physical mechanism or mechanisms is lightning initiated in the thundercloud? What is the maximum cloud electric field magnitude and over what volume of the cloud? What, if any, high energy processes (runaway electrons, X-rays, gamma rays) are involved in lightning initiation and how? What is the role of various forms of ice and water in lightning initiation? What physical mechanisms govern the propagation of the different types of lightning leaders (negative stepped, first positive, negative dart, negative dart-stepped, negative dart-chaotic) between cloud and ground and the leaders inside the cloud? What is the physical mechanism of leader attachment to elevated objects on the ground and to the flat ground? What are the characteristics of upward connecting leaders from those objects or from the ground? What is the physics of compact intra-cloud discharges (CIDs) (that produce a narrow bipolar wideband electric field pulse, a narrow bipolar event or NBE, apparently multiple-reflecting propagating waves within 1 km height, and copious HF and VHF radiation)? How are CIDs related to other types of preliminary breakdown pulses? Are CIDs related to the Terrestrial Gamma-Ray Flashes (TGFs) observed on orbiting satellites or to the Transient Luminous Events (TLEs) photographed above cloud tops, particularly to so-called “gigantic jets”? By what physical mechanisms do lightning leaders emit pulses of X-rays? Do the X-rays play a role in lightning propagation? By what mechanism do thunderclouds generate relatively-steady internal X-rays? Do X-rays and other high energy radiation affect cloud electrification and play a role in lightning initiation? By what physical mechanisms are Terrestrial Gamma-Ray Flashes (TGFs) produced? Do TGFs pose a hazard to individuals in aircraft? How do cloud-to-ground and intra-cloud lightning affect the upper atmosphere and ionosphere? What are the physics of the Transient Luminous Events (TLEs), “Sprites”, “jets”, and “elves”? What is the energy input into the ionosphere/magnetosphere from lightning? How exactly does rocket-and-wire (“classical” with a grounded wire and “altitude” with a floating wire) triggering of lightning work? Are there other possible and practical triggering techniques such as laser triggering? Can triggering reduce or eliminate the local occurrence of natural lightning? What are the power and energy of the component processes of lightning flashes and how are they distributed among electromagnetic processes (DC to light), thermal processes, mechanical (acoustic) processes, and relativistic (high energy) processes (runaway electrons, runaway positrons, X-ray, and gamma rays)? What is the physics of ball lightning? Is there more than one type of ball lightning? Questions 1, 2, 4, 5, 6, and 7 will be addressed directly in the following sections of this paper: Section 3. The Lightning Initiation Problem; Section 4. Lightning Propagation; Section 5. High-Energy Atmospheric Physics; Section 6. CIDs; and Section 7. TLEs.

The Shallow-to-Deep Transition in Convective Clouds During GoAmazon 2014/5

NASA Astrophysics Data System (ADS)

Jensen, M. P.; Gostic, C.; Giangrande, S. E.; Mechem, D. B.; Ghate, V. P.; Toto, T.

2016-12-01

Nearly two years of observations from the ARM Mobile Facility (AMF) deployed at Manacapuru, Brazil during the GOAmazon 2014/5 campaign are analyzed to investigate the environmental conditions controlling the transition from shallow to deep convective clouds. The Active Remote Sensing of Clouds (ARSCL) product, which combines radar and lidar observations to produce best estimates of cloud locations in the vertical column is used to qualitatively define four subsets of convective cloud conditions: 1,2) Transition cases (wet season, dry season), where a period of shallow convective clouds is followed by a period of deep convective clouds and 2) Non-transition cases (wet season, dry season), where shallow convective clouds persist without any subsequent development. For these subsets, observations of the time varying thermodynamic properties of the atmosphere, including the surface heat and radiative fluxes, the profiles of atmospheric state variables, and the ECMWF-derived large-scale advective tendencies, are composited to define averaged properties for each transition state. Initial analysis indicates that the transition state strongly depends on the pre-dawn free-tropospheric humidity, the convective inhibition and surface temperature and humidity with little dependence on the convective available potential energy and surface heat fluxes. The composited environmental thermodynamics are then used to force large-eddy simulations for the four transition states to further evaluate the sensitivity of the transition to the composite thermodynamics versus the importance of larger-scale forcing.

How Well Can Infrared Sounders Observe the Atmosphere and Surface Through Clouds?

NASA Technical Reports Server (NTRS)

Zhou, Daniel K.; Larar, Allen M.; Liu, Xu; Smith, William L.; Strow, L. Larrabee; Yang, Ping

2010-01-01

Infrared sounders, such as the Atmospheric Infrared Sounder (AIRS), the Infrared Atmospheric Sounding Interferometer (IASI), and the Cross-track Infrared sounder (CrIS), have a cloud-impenetrable disadvantage in observing the atmosphere and surface under opaque cloudy conditions. However, recent studies indicate that hyperspectral, infrared sounders have the ability to detect cloud effective-optical and microphysical properties and to penetrate optically thin clouds in observing the atmosphere and surface to a certain degree. We have developed a retrieval scheme dealing with atmospheric conditions with cloud presence. This scheme can be used to analyze the retrieval accuracy of atmospheric and surface parameters under clear and cloudy conditions. In this paper, we present the surface emissivity results derived from IASI global measurements under both clear and cloudy conditions. The accuracy of surface emissivity derived under cloudy conditions is statistically estimated in comparison with those derived under clear sky conditions. The retrieval error caused by the clouds is shown as a function of cloud optical depth, which helps us to understand how well infrared sounders can observe the atmosphere and surface through clouds.

Impact of Assimilated and Interactive Aerosol on Tropical Cyclogenesis

NASA Technical Reports Server (NTRS)

Reale, O.; Lau, K. M.; daSilva, A.; Matsui, T.

2014-01-01

This article investigates the impact 3 of Saharan dust on the development of tropical cyclones in the Atlantic. A global data assimilation and forecast system, the NASA GEOS-5, is used to assimilate all satellite and conventional data sets used operationally for numerical weather prediction. In addition, this new GEOS-5 version includes assimilation of aerosol optical depth from the Moderate Resolution Imaging Spectroradiometer (MODIS). The analysis so obtained comprises atmospheric quantities and a realistic 3-d aerosol and cloud distribution, consistent with the meteorology and validated against Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) and CloudSat data. These improved analyses are used to initialize GEOS-5 forecasts, explicitly accounting for aerosol direct radiative effects and their impact on the atmospheric dynamics. Parallel simulations with/without aerosol radiative effects show that effects of dust on static stability increase with time, becoming highly significant after day 5 and producing an environment less favorable to tropical cyclogenesis.

Micro pulse laser radar

NASA Technical Reports Server (NTRS)

Spinhirne, James D. (Inventor)

1993-01-01

An eye safe, compact, solid state lidar for profiling atmospheric cloud and aerosol scattering is disclosed. The transmitter of the micro pulse lidar is a diode pumped micro-J pulse energy, high repetition rate Nd:YLF laser. Eye safety is obtained through beam expansion. The receiver employs a photon counting solid state Geiger mode avalanche photodiode detector. Data acquisition is by a single card multichannel scaler. Daytime background induced quantum noise is controlled by a narrow receiver field-of-view and a narrow bandwidth temperature controlled interference filter. Dynamic range of the signal is limited to optical geometric signal compression. Signal simulations and initial atmospheric measurements indicate that micropulse lider systems are capable of detecting and profiling all significant cloud and aerosol scattering through the troposphere and into the stratosphere. The intended applications are scientific studies and environmental monitoring which require full time, unattended measurements of the cloud and aerosol height structure.

Micro pulse lidar

NASA Technical Reports Server (NTRS)

Spinhirne, James D.

1993-01-01

An eye safe, compact, solid state lidar for profiling atmospheric cloud and aerosol scattering has been demonstrated. The transmitter of the micropulse lidar is a diode pumped micro-J pulse energy, high repetition rate Nd:YLF laser. Eye safety is obtained through beam expansion. The receiver employs a photon counting solid state Geiger mode avalanche photodiode detector. Data acquisition is by a single card multichannel scaler. Daytime background induced quantum noise is controlled by a narrow receiver field-of-view and a narrow bandwidth temperature controlled interference filter. Dynamic range of the signal is limited by optical geometric signal compression. Signal simulations and initial atmospheric measurements indicate that systems built on the micropulse lidar concept are capable of detecting and profiling all significant cloud and aerosol scattering through the troposphere and into the stratosphere. The intended applications are scientific studies and environmental monitoring which require full time, unattended measurements of the cloud and aerosol height structure.

O2 A Band Studies for Cloud Detection and Algorithm Improvement

NASA Technical Reports Server (NTRS)

Chance, K. V.

1996-01-01

Detection of cloud parameters from space-based spectrometers can employ the vibrational bands of O2 in the (sup b1)Sigma(sub +)(sub g) yields X(sub 3) Sigma(sup -)(sub g) spin-forbidden electronic transition manifold, particularly the Delta nu = 0 A band. The GOME instrument uses the A band in the Initial Cloud Fitting Algorithm (ICFA). The work reported here consists of making substantial improvements in the line-by-line spectral database for the A band, testing whether an additional correction to the line shape function is necessary in order to correctly model the atmospheric transmission in this band, and calculating prototype cloud and ground template spectra for comparison with satellite measurements.

The validation of AIRS retrievals

NASA Technical Reports Server (NTRS)

Fetzer, Eric J.; Olsen, Edward T.; Chen, Luke L.; Hagan, Denise E.; Fishbein, Evan; McMillin, Larry; Zhou, Jiang; McMillan, Wallace W.

2003-01-01

The initial validation of Atmospheric Infrared Sounder (SIRS) experiment retrievals were completed in August 2003 as part of public release of version 3.0 data. The associated analyses are reported at http://daac.gsfc.nasa.gov/atmodyn/airs/, where data may be accessed. Here we describe some of those analyses, with an emphasis on cloud cleared radiances, atmospheric temperature profiles, sea surface temperature, total water vapor and atmospheric water vapor profiles. The results are applicable over ocean in the latitude band +/-40 degrees.

Assessment of Global Cloud Datasets from Satellites: Project and Database Initiated by the GEWEX Radiation Panel

NASA Technical Reports Server (NTRS)

Stubenrauch, C. J.; Rossow, W. B.; Kinne, S.; Ackerman, S.; Cesana, G.; Chepfer, H.; Getzewich, B.; Di Girolamo, L.; Guignard, A.; Heidinger, A.;

Constructing a Merged Cloud-Precipitation Radar Dataset for Tropical Convective Clouds during the DYNAMO/AMIE Experiment at Addu Atoll

DOE Office of Scientific and Technical Information (OSTI.GOV)

Feng, Zhe; McFarlane, Sally A.; Schumacher, Courtney

2014-05-16

To improve understanding of the convective processes key to the Madden-Julian-Oscillation (MJO) initiation, the Dynamics of the MJO (DYNAMO) and Atmospheric Radiation Measurement MJO Investigation Experiment (AMIE) collected four months of observations from three radars, the S-band Polarization Radar (S-Pol), the C-band Shared Mobile Atmospheric Research & Teaching Radar (SMART-R), and Ka-band Zenith Radar (KAZR) on Addu Atoll in the tropical Indian Ocean. This study compares the measurements from the S-Pol and SMART-R to those from the more sensitive KAZR in order to characterize the hydrometeor detection capabilities of the two scanning precipitation radars. Frequency comparisons for precipitating convective cloudsmore » and non-precipitating high clouds agree much better than non-precipitating low clouds for both scanning radars due to issues in ground clutter. On average, SMART-R underestimates convective and high cloud tops by 0.3 to 1.1 km, while S-Pol underestimates cloud tops by less than 0.4 km for these cloud types. S-Pol shows excellent dynamic range in detecting various types of clouds and therefore its data are well suited for characterizing the evolution of the 3D cloud structures, complementing the profiling KAZR measurements. For detecting non-precipitating low clouds and thin cirrus clouds, KAZR remains the most reliable instrument. However, KAZR is attenuated in heavy precipitation and underestimates cloud top height due to rainfall attenuation 4.3% of the time during DYNAMO/AMIE. An empirical method to correct the KAZR cloud top heights is described, and a merged radar dataset is produced to provide improved cloud boundary estimates, microphysics and radiative heating retrievals.« less

Algorithm Science to Operations for the National Polar-orbiting Operational Environmental Satellite System (NPOESS) Visible/Infrared Imager/Radiometer Suite (VIIRS)

NASA Technical Reports Server (NTRS)

Duda, James L.; Barth, Suzanna C

2005-01-01

The VIIRS sensor provides measurements for 22 Environmental Data Records (EDRs) addressing the atmosphere, ocean surface temperature, ocean color, land parameters, aerosols, imaging for clouds and ice, and more. That is, the VIIRS collects visible and infrared radiometric data of the Earth's atmosphere, ocean, and land surfaces. Data types include atmospheric, clouds, Earth radiation budget, land/water and sea surface temperature, ocean color, and low light imagery. This wide scope of measurements calls for the preparation of a multiplicity of Algorithm Theoretical Basis Documents (ATBDs), and, additionally, for intermediate products such as cloud mask, et al. Furthermore, the VIIRS interacts with three or more other sensors. This paper addresses selected and crucial elements of the process being used to convert and test an immense volume of a maturing and changing science code to the initial operational source code in preparation for launch of NPP. The integrity of the original science code is maintained and enhanced via baseline comparisons when re-hosted, in addition to multiple planned code performance reviews.

A comprehensive parameterization of heterogeneous ice nucleation of dust surrogate: laboratory study with hematite particles and its application to atmospheric models

NASA Astrophysics Data System (ADS)

Hiranuma, N.; Paukert, M.; Steinke, I.; Zhang, K.; Kulkarni, G.; Hoose, C.; Schnaiter, M.; Saathoff, H.; Möhler, O.

2014-12-01

A new heterogeneous ice nucleation parameterization that covers a wide temperature range (-36 to -78 °C) is presented. Developing and testing such an ice nucleation parameterization, which is constrained through identical experimental conditions, is important to accurately simulate the ice nucleation processes in cirrus clouds. The ice nucleation active surface-site density (ns) of hematite particles, used as a proxy for atmospheric dust particles, were derived from AIDA (Aerosol Interaction and Dynamics in the Atmosphere) cloud chamber measurements under water subsaturated conditions. These conditions were achieved by continuously changing the temperature (T) and relative humidity with respect to ice (RHice) in the chamber. Our measurements showed several different pathways to nucleate ice depending on T and RHice conditions. For instance, almost T-independent freezing was observed at -60 °C < T < -50 °C, where RHice explicitly controlled ice nucleation efficiency, while both T and RHice played roles in other two T regimes: -78 °C < T < -60 °C and -50 °C < T < -36 °C. More specifically, observations at T lower than -60 °C revealed that higher RHice was necessary to maintain a constant ns, whereas T may have played a significant role in ice nucleation at T higher than -50 °C. We implemented the new hematite-derived ns parameterization, which agrees well with previous AIDA measurements of desert dust, into two conceptual cloud models to investigate their sensitivity to the new parameterization in comparison to existing ice nucleation schemes for simulating cirrus cloud properties. Our results show that the new AIDA-based parameterization leads to an order of magnitude higher ice crystal concentrations and to an inhibition of homogeneous nucleation in lower-temperature regions. Our cloud simulation results suggest that atmospheric dust particles that form ice nuclei at lower temperatures, below -36 °C, can potentially have a stronger influence on cloud properties, such as cloud longevity and initiation, compared to previous parameterizations.

Microsecond-scale electric field pulses in cloud lightning discharges

NASA Technical Reports Server (NTRS)

Villanueva, Y.; Rakov, V. A.; Uman, M. A.; Brook, M.

1994-01-01

From wideband electric field records acquired using a 12-bit digitizing system with a 500-ns sampling interval, microsecond-scale pulses in different stages of cloud flashes in Florida and New Mexico are analyzed. Pulse occurrence statistics and waveshape characteristics are presented. The larger pulses tend to occur early in the flash, confirming the results of Bils et al. (1988) and in contrast with the three-stage representation of cloud-discharge electric fields suggested by Kitagawa and Brook (1960). Possible explanations for the discrepancy are discussed. The tendency for the larger pulses to occur early in the cloud flash suggests that they are related to the initial in-cloud channel formation processes and contradicts the common view found in the atmospheric radio-noise literature that the main sources of VLF/LF electromagnetic radiation in cloud flashes are the K processes which occur in the final, or J type, part of the cloud discharge.

Sedimentation Efficiency of Condensation Clouds in Substellar Atmospheres

NASA Astrophysics Data System (ADS)

Gao, Peter; Marley, Mark S.; Ackerman, Andrew S.

2018-03-01

Condensation clouds in substellar atmospheres have been widely inferred from spectra and photometric variability. Up until now, their horizontally averaged vertical distribution and mean particle size have been largely characterized using models, one of which is the eddy diffusion–sedimentation model from Ackerman and Marley that relies on a sedimentation efficiency parameter, f sed, to determine the vertical extent of clouds in the atmosphere. However, the physical processes controlling the vertical structure of clouds in substellar atmospheres are not well understood. In this work, we derive trends in f sed across a large range of eddy diffusivities (K zz ), gravities, material properties, and cloud formation pathways by fitting cloud distributions calculated by a more detailed cloud microphysics model. We find that f sed is dependent on K zz , but not gravity, when K zz is held constant. f sed is most sensitive to the nucleation rate of cloud particles, as determined by material properties like surface energy and molecular weight. High surface energy materials form fewer, larger cloud particles, leading to large f sed (>1), and vice versa for materials with low surface energy. For cloud formation via heterogeneous nucleation, f sed is sensitive to the condensation nuclei flux and radius, connecting cloud formation in substellar atmospheres to the objects’ formation environments and other atmospheric aerosols. These insights could lead to improved cloud models that help us better understand substellar atmospheres. For example, we demonstrate that f sed could increase with increasing cloud base depth in an atmosphere, shedding light on the nature of the brown dwarf L/T transition.

An overview of NASA's ASCENDS Mission's Lidar Measurement Requirements

NASA Astrophysics Data System (ADS)

Abshire, J. B.; Browell, E. V.; Menzies, R. T.; Lin, B.; Spiers, G. D.; Ismail, S.

2014-12-01

The objectives of NASA's ASCENDS mission are to improve the knowledge of global CO2 sources and sinks by precisely measuring the tropospheric column abundance of atmospheric CO2 and O2. The mission will use a continuously operating nadir-pointed integrated path differential absorption (IPDA) lidar in a polar orbit. The lidar offers a number of important new capabilities and will measure atmospheric CO2 globally over a wide range of challenging conditions, including at night, at high latitudes, through hazy and thin cloud conditions, and to cloud tops. The laser source enables a measurement of range, so that the absorption path length to the scattering surface will be always accurately known. The lidar approach also measures consistently in a nadir-zenith path and the narrow laser linewidth allows weighting the measurement to the lower troposphere. Using these measurements with atmospheric and flux models will allow improved estimates of CO2 fluxes and hence better understanding of the processes that exchange CO2 between the surface and atmosphere. The ASCENDS formulation team has developed a preliminary set of requirements for the lidar measurements. These were developed based on experience gained from the numerous ASCENDS airborne campaigns that have used different candidate lidar measurement techniques. They also take into account the complexity of making precise measurement of atmospheric gas columns when viewing the Earth from space. Some of the complicating factors are the widely varying reflectance and topographic heights of the Earth's land and ocean surfaces, the variety of cloud types, and the degree of cloud and aerosol absorption and scattering in the atmosphere. The requirements address the precision and bias in the measured column mixing ratio, the dynamic range of the expected surface reflected signal, the along-track sampling resolution, measurements made through thin clouds, measurements to forested and slope surfaces, range precision, measurements to cloud tops, knowledge of the laser spot position, and off-nadir pointing. These requirements are independent of the measurement approach, and are consistent with the initial mission simulation studies performed by the formulation team. This presentation will summarize the requirements along with examples that have guided their selection.

High Vertically Resolved Atmospheric and Surface/Cloud Parameters Retrieved with Infrared Atmospheric Sounding Interferometer (IASI)

NASA Technical Reports Server (NTRS)

Zhou, Daniel K.; Liu, Xu; Larar, Allen M.; Smith, WIlliam L.; Taylor, Jonathan P.; Schluessel, Peter; Strow, L. Larrabee; Mango, Stephen A.

2008-01-01

The Joint Airborne IASI Validation Experiment (JAIVEx) was conducted during April 2007 mainly for validation of the IASI on the MetOp satellite. IASI possesses an ultra-spectral resolution of 0.25/cm and a spectral coverage from 645 to 2760/cm. Ultra-spectral resolution infrared spectral radiance obtained from near nadir observations provide atmospheric, surface, and cloud property information. An advanced retrieval algorithm with a fast radiative transfer model, including cloud effects, is used for atmospheric profile and cloud parameter retrieval. This physical inversion scheme has been developed, dealing with cloudy as well as cloud-free radiance observed with ultraspectral infrared sounders, to simultaneously retrieve surface, atmospheric thermodynamic, and cloud microphysical parameters. A fast radiative transfer model, which applies to the cloud-free and/or clouded atmosphere, is used for atmospheric profile and cloud parameter retrieval. A one-dimensional (1-d) variational multi-variable inversion solution is used to improve an iterative background state defined by an eigenvector-regression-retrieval. The solution is iterated in order to account for non-linearity in the 1-d variational solution. It is shown that relatively accurate temperature and moisture retrievals are achieved below optically thin clouds. For optically thick clouds, accurate temperature and moisture profiles down to cloud top level are obtained. For both optically thin and thick cloud situations, the cloud top height can be retrieved with relatively high accuracy (i.e., error < 1 km). Preliminary retrievals of atmospheric soundings, surface properties, and cloud optical/microphysical properties with the IASI observations are obtained and presented. These retrievals will be further inter-compared with those obtained from airborne FTS system, such as the NPOESS Airborne Sounder Testbed - Interferometer (NAST-I), dedicated dropsondes, radiosondes, and ground based Raman Lidar. The capabilities of satellite ultra-spectral sounder such as the IASI are investigated indicating a high vertical structure of atmosphere is retrieved.

Development and Initial Testing of a Multi-Sensor Platform for Cloud-Aerosol Interactions in the Lower Troposphere

NASA Astrophysics Data System (ADS)

Nehrir, A. R.; Hoffman, D. S.; Repasky, K. S.; Todt, B.; Sharpe, T.; Half Red, C.; Carlsten, J. L.

2009-12-01

Coupled atmospheric components of the lower troposphere including aerosols and water vapor have a large affect on the chemical processes that drive the earth’s complex climate system. Aerosols can affect the earth’s global radiation budget directly by absorbing or reflecting incoming solar radiation, and indirectly by changing the microphysical properties of clouds by serving as cloud condensation nuclei (CCN). An increase in CCN results in higher cloud droplet concentration which has been shown to suppress drizzle formation and lead to more reflective clouds. The changes in the cloud microphysical structure due to the interaction of aerosols and water vapor result in more incoming solar radiation being reflected back into space, leading to a net negative radiative forcing in the global radiation budget. The uncertainty in this radiative forcing reflects the uncertainty in the understanding of the aerosol indirect effect and its role in the climate system. To better understand the aerosol direct and indirect effects, lidar measurements of aerosol properties and water vapor distributions can provide important information to enhance our understanding of the role of aerosols in the climate system. The LIDAR group at Montana State University has initiated a program to simultaneously study aerosols, water vapor, and cloud formation with high spatial and temporal resolution using both active and passive sensors. Aerosol distributions and radiative properties are currently being studied with a two-color LIDAR system at 1064 and 532 nm. In addition, a three color, high spectral resolution LIDAR system at 1064,532, and 355 nm has also been developed and is starting to take initial data. Daytime and nighttime boundary layer water vapor number density profiles are also currently being studied with an external cavity diode oscillator/diode amplifier based micro-pulsed differential absorption lidar (DIAL) instrument at the 830 nm water vapor absorption band. Cloud formation studies are being conducted by a simultaneous, spatially correlated digital sky imaging camera system where aerosol loading and water vapor distributions are monitored as a function of lateral distance to clouds. Furthermore, a commercially purchased sun/sky scanning solar radiometer (CIMEL 318) as part of the NASA run AERONET program is also being used to study aerosol loading and radiative transfer through the atmosphere. A brief description of these instruments will be presented as well as initial simultaneous results showing correlated data between lower tropospheric aerosols and boundary layer water vapor distributions over extended periods if time.

Contrasting sea-ice and open-water boundary layers during melt and freeze-up seasons: Some result from the Arctic Clouds in Summer Experiment.

NASA Astrophysics Data System (ADS)

Tjernström, Michael; Sotiropoulou, Georgia; Sedlar, Joseph; Achtert, Peggy; Brooks, Barbara; Brooks, Ian; Persson, Ola; Prytherch, John; Salsbury, Dominic; Shupe, Matthew; Johnston, Paul; Wolfe, Dan

2016-04-01

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 Clouds 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-layer conditions as summer turned into autumn. During summer, strong surface inversions persisted over sea ice, while well-mixed boundary layers 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 clouds often persisted over the ice, whereas low-level liquid-water clouds developed over open water. These differences largely disappeared in autumn, when mixed-phase clouds 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-layer structure in summer, the surface was often warmer than the atmosphere in autumn, regardless of surface type. Hence the autumn boundary-layer structure was more dependent on synoptic scale meteorology.

Photolysis rates in correlated overlapping cloud fields: Cloud-J 7.3

DOE PAGES

Prather, M. J.

2015-05-27

A new approach for modeling photolysis rates ( J values) in atmospheres with fractional cloud cover has been developed and implemented as Cloud-J – a multi-scattering eight-stream radiative transfer model for solar radiation based on Fast-J. Using observed statistics for the vertical correlation of cloud layers, Cloud-J 7.3 provides a practical and accurate method for modeling atmospheric chemistry. The combination of the new maximum-correlated cloud groups with the integration over all cloud 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 » Cloud-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 cloud groups, or 1 call with the simplest cloud approximations. Another improvement in modeling J values, the treatment of volatile organic compounds with pressure-dependent cross sections is also incorporated into Cloud-J.« less

Photolysis rates in correlated overlapping cloud fields: Cloud-J 7.3c

DOE PAGES

Prather, M. J.

2015-08-14

A new approach for modeling photolysis rates ( J values) in atmospheres with fractional cloud cover has been developed and is implemented as Cloud-J – a multi-scattering eight-stream radiative transfer model for solar radiation based on Fast-J. Using observations of the vertical correlation of cloud layers, Cloud-J 7.3c provides a practical and accurate method for modeling atmospheric chemistry. The combination of the new maximum-correlated cloud groups with the integration over all cloud 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. Cloud-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 cloud groups, or 1 call with the simplest cloud approximations. Another improvement in modeling J values, the treatment of volatile organic compounds with pressure-dependent cross sections, is also incorporated into Cloud-J.« less

3D MODELING OF GJ1214b's ATMOSPHERE: FORMATION OF INHOMOGENEOUS HIGH CLOUDS AND OBSERVATIONAL IMPLICATIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Charnay, B.; Meadows, V.; Misra, A.

2015-11-01

The warm sub-Neptune GJ1214b has a featureless transit spectrum that may be due to the presence of high and thick clouds or haze. Here, we simulate the atmosphere of GJ1214b with a 3D General Circulation Model for cloudy hydrogen-dominated atmospheres, including cloud radiative effects. We show that the atmospheric circulation is strong enough to transport micrometric cloud particles to the upper atmosphere and generally leads to a minimum of cloud at the equator. By scattering stellar light, clouds increase the planetary albedo to 0.4–0.6 and cool the atmosphere below 1 mbar. However, the heating by ZnS clouds leads to themore » formation of a stratospheric thermal inversion above 10 mbar, with temperatures potentially high enough on the dayside to evaporate KCl clouds. We show that flat transit spectra consistent with Hubble Space Telescope observations are possible if cloud particle radii are around 0.5 μm, and that such clouds should be optically thin at wavelengths >3 μm. Using simulated cloudy atmospheres that fit the observed spectra we generate transit, emission, and reflection spectra and phase curves for GJ1214b. We show that a stratospheric thermal inversion would be readily accessible in near- and mid-infrared atmospheric spectral windows. We find that the amplitude of the thermal phase curves is strongly dependent on metallicity, but only slightly impacted by clouds. Our results suggest that primary and secondary eclipses and phase curves observed by the James Webb Space Telescope in the near- to mid-infrared should provide strong constraints on the nature of GJ1214b's atmosphere and clouds.« less

The Algorithm Theoretical Basis Document for the GLAS Atmospheric Data Products

NASA Technical Reports Server (NTRS)

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

2012-01-01

The purpose of this document is to present a detailed description of the algorithm theoretical basis for each of the GLAS data products. This will be the final version of this document. The algorithms were initially designed and written based on the authors prior experience with high altitude lidar data on systems such as the Cloud and Aerosol Lidar System (CALS) and the Cloud Physics Lidar (CPL), both of which fly on the NASA ER-2 high altitude aircraft. These lidar systems have been employed in many field experiments around the world and algorithms have been developed to analyze these data for a number of atmospheric parameters. CALS data have been analyzed for cloud top height, thin cloud optical depth, cirrus cloud emittance (Spinhirne and Hart, 1990) and boundary layer depth (Palm and Spinhirne, 1987, 1998). The successor to CALS, the CPL, has also been extensively deployed in field missions since 2000 including the validation of GLAS and CALIPSO. The CALS and early CPL data sets also served as the basis for the construction of simulated GLAS data sets which were then used to develop and test the GLAS analysis algorithms.

Competition for water vapour results in suppression of ice formation in mixed-phase clouds

NASA Astrophysics Data System (ADS)

Simpson, Emma L.; Connolly, Paul J.; McFiggans, Gordon

2018-05-01

The formation of ice in clouds can initiate precipitation and influence a cloud's reflectivity and lifetime, affecting climate to a highly uncertain degree. Nucleation of ice at elevated temperatures requires an ice nucleating particle (INP), which results in so-called heterogeneous freezing. Previously reported measurements for the ability of a particle to nucleate ice have been made in the absence of other aerosol which will act as cloud condensation nuclei (CCN) and are ubiquitous in the atmosphere. Here we show that CCN can outcompete INPs for available water vapour thus suppressing ice formation, which has the potential to significantly affect the Earth's radiation budget. The magnitude of this suppression is shown to be dependent on the mass of condensed water required for freezing. Here we show that ice formation in a state-of-the-art cloud parcel model is strongly dependent on the criteria for heterogeneous freezing selected from those previously hypothesised. We have developed an alternative criteria which agrees well with observations from cloud chamber experiments. This study demonstrates the dominant role that competition for water vapour can play in ice formation, highlighting both a need for clarity in the requirements for heterogeneous freezing and for measurements under atmospherically appropriate conditions.

Atmospheric, Cloud, and Surface Parameters Retrieved from Satellite Ultra-spectral Infrared Sounder Measurements

NASA Technical Reports Server (NTRS)

Zhou, Daniel K.; Liu, Xu; Larar, Allen M.; Smith, William L.; Yang, Ping; Schluessel, Peter; Strow, Larrabee

2007-01-01

An advanced retrieval algorithm with a fast radiative transfer model, including cloud effects, is used for atmospheric profile and cloud parameter retrieval. This physical inversion scheme has been developed, dealing with cloudy as well as cloud-free radiance observed with ultraspectral infrared sounders, to simultaneously retrieve surface, atmospheric thermodynamic, and cloud microphysical parameters. A fast radiative transfer model, which applies to the clouded atmosphere, is used for atmospheric profile and cloud parameter retrieval. A one-dimensional (1-d) variational multivariable inversion solution is used to improve an iterative background state defined by an eigenvector-regression-retrieval. The solution is iterated in order to account for non-linearity in the 1-d variational solution. This retrieval algorithm is applied to the MetOp satellite Infrared Atmospheric Sounding Interferometer (IASI) launched on October 19, 2006. IASI possesses an ultra-spectral resolution of 0.25 cm(exp -1) and a spectral coverage from 645 to 2760 cm(exp -1). Preliminary retrievals of atmospheric soundings, surface properties, and cloud optical/microphysical properties with the IASI measurements are obtained and presented.

Ionisation in ultra-cool, cloud forming extrasolar planetary atmospheres

NASA Astrophysics Data System (ADS)

Helling, Christiane; the LEAP Team

2015-04-01

Transit spectroscopy provides evidence that extrasolare planets are covered in clouds, a finding that has been forecast by cloud model simulations 15 years ago. Atmospheres are strongly affected by clouds through their large opacity and their chemical activity. Cloud formation models allow to predict cloud particle sizes, their chemical composition and the composition of the remaining atmospheric gas (Woitke & Helling 2004, A&A 414; Helling & Woitke 2006, A&A 455), for example, as input for radiative transfer codes like Drift-Phoenix (Witte et al. 2009; A&A 506). These cloud particles are charged and can discharge, for example in form of lighting (Helling et al. 2013, ApJ 767; Bailey et al. 2014, ApJ 784). Earth observations demonstrate that lighting effects not only the local chemistry but also the electron budget of the atmosphere. This talk will present our work on cloud formation modelling and ionisation processes in cloud forming atmospheres. An hierarchy of ionisation processes leads to a vertically inhomogenously ionised atmosphere which has implications for planetary mass loss and global circulation pattern of planetary atmospheres. Processes involved, like Cosmic Ray ionisation, do also activate the local chemistry such that large hydrocarbon molecules form (Rimmer et al. 2014, IJAsB 13).

Harmonization of Initial Estimates of Shale Gas Life Cycle Greenhouse Gas Emissions for Electric Power Generation

NASA Astrophysics Data System (ADS)

Hiranuma, N.; Hoose, C.; Järvinen, E.; Kiselev, A. A.; Moehler, O.; Schnaiter, M.; Ullrich, R.; Cziczo, D. J.; Felgitsch, L.; Gourihar, K.; Grothe, H.; Reicher, N.; Rudich, Y.; Tobo, Y.; Zawadowicz, M. A.

2014-12-01

Glaciation of supercooled clouds through immersion freezing is an important atmospheric process affecting the formation of precipitation and the Earth's energy budget. Currently, the climatic impact of ice-nucleating particles (INPs) is being reassessed due to increasing evidence of their diversity and abundance in the atmosphere as well as their ability to influence cloud properties. Recently, it has been found that microcrystalline cellulose (MCC; extracted from natural wood pulp) can act as an efficient INP and may add crucial importance to quantify the role of primary biological INP (BINP) in the troposphere. However, it is still unclear if the laboratory results of MCC can be representatively scaled up to the total cellulose content in the atmosphere to assess the overall role of BINPs in clouds and the climate system. Here, we use the AIDA (Aerosol Interaction and Dynamics in the Atmosphere) cloud simulation chamber in Karlsruhe, Germany to demonstrate that several important plant constituents as well as natural plant debris can act as BINPs in simulated super-cooled clouds of the lower and middle troposphere. More specifically, we measured the surface-scaled ice nucleation activity of a total 16 plant structural materials (i.e., celluloses, lignins, lipids and carbohydrates), which were dispersed and immersed in cloud droplets in the chamber, and compared to that of dried leaf powder as a model proxy for atmospheric BINPs. Using these surface-based activities, we developed parameters describing the ice nucleation ability of these particles. Subsequently, we applied them to observed airborne plant debris concentrations and compared to the background INP simulated in a global aerosol model. Our results suggest that cellulose is the most active BINPs amongst the 16 materials and the concentration of ice nucleating cellulose and plant debris to become significant (>0.1 L-1) below about -20 ˚C. Overall, our findings support the view that MCC may be a good proxy for inferring ice nucleating properties of natural plant debris. More atmospheric observations of airborne cellulose-containing particles are necessary to allow better estimates of their effects on clouds and the global climate. Acknowledgement: We acknowledge support by German Research Society (DFG) and Ice Nuclei research UnIT (FOR 1525 INUIT).

Cloud Base Height Measurements at Manila Observatory: Initial Results from Constructed Paired Sky Imaging Cameras

NASA Astrophysics Data System (ADS)

Lagrosas, N.; Tan, F.; Antioquia, C. T.

2014-12-01

Fabricated all sky imagers are efficient and cost effective instruments for cloud detection and classification. Continuous operation of this instrument can result in the determination of cloud occurrence and cloud base heights for the paired system. In this study, a fabricated paired sky imaging system - consisting two commercial digital cameras (Canon Powershot A2300) enclosed in weatherproof containers - is developed in Manila Observatory for the purpose of determining cloud base heights at the Manila Observatory area. One of the cameras is placed on the rooftop of Manila Observatory and the other is placed on the rooftop of the university dormitory, 489m from the first camera. The cameras are programmed to simultaneously gather pictures every 5 min. Continuous operation of these cameras were implemented since the end of May of 2014 but data collection started end of October 2013. The data were processed following the algorithm proposed by Kassianov et al (2005). The processing involves the calculation of the merit function that determines the area of overlap of the two pictures. When two pictures are overlapped, the minimum of the merit function corresponds to the pixel column positions where the pictures have the best overlap. In this study, pictures of overcast sky prove to be difficult to process for cloud base height and were excluded from processing. The figure below shows the initial results of the hourly average of cloud base heights from data collected from November 2013 to July 2014. Measured cloud base heights ranged from 250m to 1.5km. These are the heights of cumulus and nimbus clouds that are dominant in this part of the world. Cloud base heights are low in the early hours of the day indicating low convection process during these times. However, the increase in the convection process in the atmosphere can be deduced from higher cloud base heights in the afternoon. The decrease of cloud base heights after 15:00 follows the trend of decreasing solar energy in the atmosphere after this time. The results show the potential of these instruments to determine cloud base heights on prolonged time intervals. The continuous operation of these instruments is implemented to gather seasonal variation of cloud base heights in this part of the world and to add to the much-needed dataset for future climate studies in Manila Observatory.

Glacial Inception in north-east Canada: The Role of Topography and Clouds

NASA Astrophysics Data System (ADS)

Birch, Leah; Tziperman, Eli; Cronin, Timothy

2016-04-01

Over the past 0.8 million years, ice ages have dominated Earth's climate on a 100 thousand year cycle. Interglacials were brief, sometimes lasting only a few thousand years, leading to the next inception. Currently, state-of-the-art global climate models (GCMs) are incapable of simulating the transition of Earth's climate from interglacial to glaciated. We hypothesize that this failure may be related to their coarse spatial resolution, which does not allow resolving the topography of inception areas, and their parameterized representation of clouds and atmospheric convection. To better understand the small scale topographic and cloud processes mis-represented by GCMs, we run the Weather Research and Forecasting model (WRF), which is a regional, cloud-resolving atmospheric model capable of a realistic simulation of the regional mountain climate and therefore of surface ice and snow mass balance. We focus our study on the mountain glaciers of Canada's Baffin Island, where geologic evidence indicates the last inception occurred at 115kya. We examine the sensitivity of mountain glaciers to Milankovitch Forcing, topography, and meteorology, while observing impacts of a cloud resolving model. We first verify WRF's ability to simulate present day climate in the region surrounding the Penny Ice Cap, and then investigate how a GCM-like biased representation of topography affects sensitivity of this mountain glacier to Milankovitch forcing. Our results show the possibility of ice cap growth on an initially snow-free landscape with realistic topography and insolation values from the last glacial inception. Whereas, smoothed topography as seen in GCMs has a negative surface mass balance, even with the relevant orbital parameter configuration. We also explore the surface mass balance feedbacks from an initially ice-covered Baffin Island and discuss the role of clouds and convection.

Optimal contrast elastic lidar sensing of clear and aerosol-loaded atmosphere

NASA Astrophysics Data System (ADS)

Evgenieva, Tsvetina T.; Gurdev, Ljuan L.

2016-01-01

The sensing laser radiation wavelength is one of the most significant factors conditioning the elastic lidar efficiency. Nevertheless, its role in the process of lidar sensing has not been investigated systematically so far. Therefore, the main purpose of the present work is to develop and perform an initial examination of an approach to solve this problem based on modeling the profile of the lidar return signal (the lidar profile) and evaluating, in a specific way, the corresponding profile of the measurement signal-to-noise ratio (SNR). The measurement fluctuations are considered as mainly due to the Poisson shot noise that is intrinsic to the dark current and the photocurrent induced by the useful signal itself and the atmospheric background. The initial results obtained show for instance that for ground-based lidar facilities the maximum Rayleigh return signal is obtainable at wavelengths about 350nm. The roles are changed when sensing clouds using wavelength from 400nm to 1000-2000nm. Then, the longer wavelengths provide higher return power from clouds, and the effect is magnified in aerosol-loaded (and especially hazy) atmosphere. The results of such investigations are useful when selecting optimal lidar-design characteristics ensuring maximum brightness and contrast of the lidar-acquired images of specific aerosol strata and objects in the atmosphere.

Terminal Area Simulation System User's Guide - Version 10.0

NASA Technical Reports Server (NTRS)

Switzer, George F.; Proctor, Fred H.

2014-01-01

The Terminal Area Simulation System (TASS) is a three-dimensional, time-dependent, large eddy simulation model that has been developed for studies of wake vortex and weather hazards to aviation, along with other atmospheric turbulence, and cloud-scale weather phenomenology. This document describes the source code for TASS version 10.0 and provides users with needed documentation to run the model. The source code is programed in Fortran language and is formulated to take advantage of vector and efficient multi-processor scaling for execution on massively-parallel supercomputer clusters. The code contains different initialization modules allowing the study of aircraft wake vortex interaction with the atmosphere and ground, atmospheric turbulence, atmospheric boundary layers, precipitating convective clouds, hail storms, gust fronts, microburst windshear, supercell and mesoscale convective systems, tornadic storms, and ring vortices. The model is able to operate in either two- or three-dimensions with equations numerically formulated on a Cartesian grid. The primary output from the TASS is time-dependent domain fields generated by the prognostic equations and diagnosed variables. This document will enable a user to understand the general logic of TASS, and will show how to configure and initialize the model domain. Also described are the formats of the input and output files, as well as the parameters that control the input and output.

Combined Lidar-Radar Remote Sensing: Initial Results from CRYSTAL-FACE and Implications for Future Spaceflight Missions

NASA Technical Reports Server (NTRS)

McGill, Matthew J.; Li, Li-Hua; Hart, William D.; Heymsfield, Gerald M.; Hlavka, Dennis L.; Vaughan, Mark A.; Winker, David M.

2003-01-01

In the near future NASA plans to fly satellites carrying a multi-wavelength backscatter lidar and a 94-GHz cloud profiling radar in formation to provide complete global profiling of cloud and aerosol properties. The CRYSTAL-FACE field campaign, conducted during July 2002, provided the first high-altitude colocated measurements from lidar and cloud profiling radar to simulate these spaceborne sensors. The lidar and radar provide complementary measurements with varying degrees of measurement overlap. This paper presents initial results of the combined airborne lidar-radar measurements during CRYSTAL-FACE. The overlap of instrument sensitivity is presented, within the context of particular CRYSTAL-FACE conditions. Results are presented to quantify the portion of atmospheric profiles sensed independently by each instrument and the portion sensed simultaneously by the two instruments.

CTRANS: A Monte Carlo program for radiative transfer in plane parallel atmospheres with imbedded finite clouds: Development, testing and user's guide

NASA Technical Reports Server (NTRS)

1976-01-01

The program called CTRANS is described which was designed to perform radiative transfer computations in an atmosphere with horizontal inhomogeneities (clouds). Since the atmosphere-ground system was to be richly detailed, the Monte Carlo method was employed. This means that results are obtained through direct modeling of the physical process of radiative transport. The effects of atmopheric or ground albedo pattern detail are essentially built up from their impact upon the transport of individual photons. The CTRANS program actually tracks the photons backwards through the atmosphere, initiating them at a receiver and following them backwards along their path to the Sun. The pattern of incident photons generated through backwards tracking automatically reflects the importance to the receiver of each region of the sky. Further, through backwards tracking, the impact of the finite field of view of the receiver and variations in its response over the field of view can be directly simulated.

Challenges and opportunities of cloud computing for atmospheric sciences

NASA Astrophysics Data System (ADS)

Pérez Montes, Diego A.; Añel, Juan A.; Pena, Tomás F.; Wallom, David C. H.

2016-04-01

Cloud computing is an emerging technological solution widely used in many fields. Initially developed as a flexible way of managing peak demand it has began to make its way in scientific research. One of the greatest advantages of cloud computing for scientific research is independence of having access to a large cyberinfrastructure to fund or perform a research project. Cloud computing can avoid maintenance expenses for large supercomputers and has the potential to 'democratize' the access to high-performance computing, giving flexibility to funding bodies for allocating budgets for the computational costs associated with a project. Two of the most challenging problems in atmospheric sciences are computational cost and uncertainty in meteorological forecasting and climate projections. Both problems are closely related. Usually uncertainty can be reduced with the availability of computational resources to better reproduce a phenomenon or to perform a larger number of experiments. Here we expose results of the application of cloud computing resources for climate modeling using cloud computing infrastructures of three major vendors and two climate models. We show how the cloud infrastructure compares in performance to traditional supercomputers and how it provides the capability to complete experiments in shorter periods of time. The monetary cost associated is also analyzed. Finally we discuss the future potential of this technology for meteorological and climatological applications, both from the point of view of operational use and research.

Concept, Simulation, and Instrumentation for Radiometric Inflight Icing Detection

NASA Technical Reports Server (NTRS)

Ryerson, Charles; Koenig, George G.; Reehorst, Andrew L.; Scott, Forrest R.

2009-01-01

The multi-agency Flight in Icing Remote Sensing Team (FIRST), a consortium of the National Aeronautics and Space Administration (NASA), the Federal Aviation Administration (FAA), the National Center for Atmospheric Research (NCAR), the National Oceanographic and Atmospheric Administration (NOAA), and the Army Corps of Engineers (USACE), has developed technologies for remotely detecting hazardous inflight icing conditions. The USACE Cold Regions Research and Engineering Laboratory (CRREL) assessed the potential of onboard passive microwave radiometers for remotely detecting icing conditions ahead of aircraft. The dual wavelength system differences the brightness temperature of Space and clouds, with greater differences potentially indicating closer and higher magnitude cloud liquid water content (LWC). The Air Force RADiative TRANsfer model (RADTRAN) was enhanced to assess the flight track sensing concept, and a 'flying' RADTRAN was developed to simulate a radiometer system flying through simulated clouds. Neural network techniques were developed to invert brightness temperatures and obtain integrated cloud liquid water. In addition, a dual wavelength Direct-Detection Polarimeter Radiometer (DDPR) system was built for detecting hazardous drizzle drops. This paper reviews technology development to date and addresses initial polarimeter performance.

Agglomeration of dust in convective clouds initialized by nuclear bursts

NASA Astrophysics Data System (ADS)

Bacon, D. P.; Sarma, R. A.

Convective clouds initialized by nuclear bursts are modeled using a two-dimensional axisymmetric cloud model. Dust transport through the atmosphere is studied using five different sizes ranging from 1 to 10,000 μm in diameter. Dust is transported in the model domain by advection and sedimentation. Water is allowed to condense onto dust particles in regions of supersaturation in the cloud. The agglomeration of dust particles resulting from the collision of different size dust particles is modeled. The evolution of the dust mass spectrum due to agglomeration is modeled using a numerical scheme which is mass conserving and has low implicit diffusion. Agglomeration moves mass from the small particles with very small fall velocity to the larger sizes which fall to the ground more readily. Results indicate that the dust fallout can be increased significantly due to this process. In preliminary runs using stable and unstable environmental soundings, at 30 min after detonation the total dust in the domain was 11 and 30%, respectively, less than a control case without agglomeration.

Aerosol and cloud properties derived from hyperspectral transmitted light in the southeast Atlantic sampled during field campaign deployments in 2016 and 2017

NASA Astrophysics Data System (ADS)

LeBlanc, S. E.; Redemann, J.; Flynn, C. J.; Segal-Rosenhaimer, M.; Kacenelenbogen, M. S.; Shinozuka, Y.; Pistone, K.; Karol, Y.; Schmidt, S.; Cochrane, S.; Chen, H.; Meyer, K.; Ferrare, R. A.; Burton, S. P.; Hostetler, C. A.; Hair, J. W.

2017-12-01

We present aerosol and cloud properties collected from airborne remote-sensing measurements in the southeast Atlantic during the recent NASA ObseRvations of CLouds above Aerosols and their intEractionS (ORACLES) field campaign. During the biomass burning seasons of September 2016 and August 2017, we sampled aerosol layers which overlaid marine stratocumulus clouds off the southwestern coast of Africa. We sampled these aerosol layers and the underlying clouds from the NASA P3 airborne platform with the Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research (4STAR). Aerosol optical depth (AOD), along with trace gas content in the atmospheric column (water vapor, NO2, and O3), is obtained from the attenuation in the sun's direct beam, measured at the altitude of the airborne platform. Using hyperspectral transmitted light measurements from 4STAR, in conjunction with hyperspectral hemispheric irradiance measurements from the Solar Spectral Flux Radiometers (SSFR), we also obtained aerosol intensive properties (asymmetry parameter, single scattering albedo), aerosol size distributions, cloud optical depth (COD), cloud particle effective radius, and cloud thermodynamic phase. Aerosol intensive properties are retrieved from measurements of angularly resolved skylight and flight level spectral albedo using the inversion used with measurements from AERONET (Aerosol Robotic Network) that has been modified for airborne use. The cloud properties are obtained from 4STAR measurements of scattered light below clouds. We show a favorable initial comparison of the above-cloud AOD measured by 4STAR to this same product retrieved from measurements by the MODIS instrument on board the TERRA and AQUA satellites. The layer AOD observed above clouds will also be compared to integrated aerosol extinction profile measurements from the High Spectral Resolution Lidar-2 (HSRL-2).

Implications of Atmospheric Test Fallout Data for Nuclear Winter.

NASA Astrophysics Data System (ADS)

Baker, George Harold, III

1987-09-01

Atmospheric test fallout data have been used to determine admissable dust particle size distributions for nuclear winter studies. The research was originally motivated by extreme differences noted in the magnitude and longevity of dust effects predicted by particle size distributions routinely used in fallout predictions versus those used for nuclear winter studies. Three different sets of historical data have been analyzed: (1) Stratospheric burden of Strontium -90 and Tungsten-185, 1954-1967 (92 contributing events); (2) Continental U.S. Strontium-90 fallout through 1958 (75 contributing events); (3) Local Fallout from selected Nevada tests (16 events). The contribution of dust to possible long term climate effects following a nuclear exchange depends strongly on the particle size distribution. The distribution affects both the atmospheric residence time and optical depth. One dimensional models of stratospheric/tropospheric fallout removal were developed and used to identify optimum particle distributions. Results indicate that particle distributions which properly predict bulk stratospheric activity transfer tend to be somewhat smaller than number size distributions used in initial nuclear winter studies. In addition, both ^{90}Sr and ^ {185}W fallout behavior is better predicted by the lognormal distribution function than the prevalent power law hybrid function. It is shown that the power law behavior of particle samples may well be an aberration of gravitational cloud stratification. Results support the possible existence of two independent particle size distributions in clouds generated by surface or near surface bursts. One distribution governs late time stratospheric fallout, the other governs early time fallout. A bimodal lognormal distribution is proposed to describe the cloud particle population. The distribution predicts higher initial sunlight attenuation and lower late time attenuation than the power law hybrid function used in initial nuclear winter studies.

Cloud Type Classification (cldtype) Value-Added Product

DOE Office of Scientific and Technical Information (OSTI.GOV)

Flynn, Donna; Shi, Yan; Lim, K-S

The Cloud Type (cldtype) value-added product (VAP) provides an automated cloud type classification based on macrophysical quantities derived from vertically pointing lidar and radar. Up to 10 layers of clouds are classified into seven cloud types based on predetermined and site-specific thresholds of cloud top, base and thickness. Examples of thresholds for selected U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Climate Research Facility sites are provided in Tables 1 and 2. Inputs for the cldtype VAP include lidar and radar cloud boundaries obtained from the Active Remotely Sensed Cloud Location (ARSCL) and Surface Meteorological Systems (MET) data. Rainmore » rates from MET are used to determine when radar signal attenuation precludes accurate cloud detection. Temporal resolution and vertical resolution for cldtype are 1 minute and 30 m respectively and match the resolution of ARSCL. The cldtype classification is an initial step for further categorization of clouds. It was developed for use by the Shallow Cumulus VAP to identify potential periods of interest to the LASSO model and is intended to find clouds of interest for a variety of users.« less

Sensitivity of Shallow Convection in Large-Eddy Simulations to Forcing Datasets Across a Range of Days: Examining Results from the DOE LASSO Projec

NASA Astrophysics Data System (ADS)

Gustafson, W. I., Jr.; Vogelmann, A. M.; Li, Z.; Cheng, X.; Endo, S.; Krishna, B.; Toto, T.; Xiao, H.

2017-12-01

Large-eddy simulation (LES) is a powerful tool for understanding atmospheric turbulence and cloud development. However, the results are sensitive to the choice of forcing data sets used to drive the LES model, and the most realistic forcing data is difficult to identify a priori. Knowing the sensitivity of boundary layer and cloud processes to forcing data selection is critical when using LES to understand atmospheric processes and when developing associated parameterizations. The U.S. Department of Energy Atmospheric Radiation Measurement (ARM) User Facility has been developing the capability to routinely generate ensembles of LES based on a selection of plausible input forcing data sets. The LES ARM Symbiotic Simulation and Observation (LASSO) project is initially generating simulations for shallow convection days at the ARM Southern Great Plains site in Oklahoma. This talk will examine 13 days with shallow convection selected from the period May-August 2016, with multiple forcing sources and spatial scales used to generate an LES ensemble for each of the days, resulting in hundreds of LES runs with coincident observations from ARM's extensive suite of in situ and retrieval-based products. This talk will focus particularly on the sensitivity of the cloud development and its relation to forcing data. Variability of the PBL characteristics, lifting condensation level, cloud base height, cloud fraction, and liquid water path will be examined. More information about the LASSO project can be found at https://www.arm.gov/capabilities/modeling/lasso.

Clouds in the Martian Atmosphere

NASA Astrophysics Data System (ADS)

Määttänen, Anni; Montmessin, Franck

2018-01-01

Although resembling an extremely dry desert, planet Mars hosts clouds in its atmosphere. Every day somewhere on the planet a part of the tiny amount of water vapor held by the atmosphere can condense as ice crystals to form cirrus-type clouds. The existence of water ice clouds has been known for a long time, and they have been studied for decades, leading to the establishment of a well-known climatology and understanding of their formation and properties. Despite their thinness, they have a clear impact on the atmospheric temperatures, thus affecting the Martian climate. Another, more exotic type of clouds forms as well on Mars. The atmospheric temperatures can plunge to such frigid values that the major gaseous component of the atmosphere, CO2, condenses as ice crystals. These clouds form in the cold polar night where they also contribute to the formation of the CO2 ice polar cap, and also in the mesosphere at very high altitudes, near the edge of space, analogously to the noctilucent clouds on Earth. The mesospheric clouds are a fairly recent discovery and have put our understanding of the Martian atmosphere to a test. On Mars, cloud crystals form on ice nuclei, mostly provided by the omnipresent dust. Thus, the clouds link the three major climatic cycles: those of the two major volatiles, H2O and CO2; and that of dust, which is a major climatic agent itself.

Characterization of clouds in Titan's tropical atmosphere

USGS Publications Warehouse

Griffith, C.A.; Penteado, P.; Rodriguez, S.; Le, Mouelic S.; Baines, K.H.; Buratti, B.; Clark, R.; Nicholson, P.; Jaumann, R.; Sotin, Christophe

2009-01-01

Images of Titan's clouds, possible over the past 10 years, indicate primarily discrete convective methane clouds near the south and north poles and an immense stratiform cloud, likely composed of ethane, around the north pole. Here we present spectral images from Cassini's Visual Mapping Infrared Spectrometer that reveal the increasing presence of clouds in Titan's tropical atmosphere. Radiative transfer analyses indicate similarities between summer polar and tropical methane clouds. Like their southern counterparts, tropical clouds consist of particles exceeding 5 ??m. They display discrete structures suggestive of convective cumuli. They prevail at a specific latitude band between 8??-20?? S, indicative of a circulation origin and the beginning of a circulation turnover. Yet, unlike the high latitude clouds that often reach 45 km altitude, these discrete tropical clouds, so far, remain capped to altitudes below 26 km. Such low convective clouds are consistent with the highly stable atmospheric conditions measured at the Huygens landing site. Their characteristics suggest that Titan's tropical atmosphere has a dry climate unlike the south polar atmosphere, and despite the numerous washes that carve the tropical landscape. ?? 2009. The American Astronomical Society.

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

The remote atmosphere over the Amazon can be similar to oceanic regions in terms of aerosol conditions and cloud type formations. This is especially true during the wet season. The main aerosol-related disturbances over the Amazon have both natural sources, such as dust transport from Africa, and anthropogenic sources, such as biomass burning or urban pollution. The present work considers the impacts of the latter on the microphysical properties of warm-phase clouds by analysing observations of the interactions between the Manaus pollution plume and its surroundings, as part of the GoAmazon2014/5 Experiment. The analysed period corresponds to the wet seasonmore » (specifically from February to March 2014 and corresponding to the first Intensive Operating Period (IOP1) of GoAmazon2014/5). The droplet size distributions reported are in the range 1 µm ≤ D≤50 µm in order to capture the processes leading up to the precipitation formation. The wet season largely presents a clean background atmosphere characterized by frequent rain showers. As such, the contrast between background clouds and those affected by the Manaus pollution can be observed and detailed. The focus is on the characteristics of the initial microphysical properties in cumulus clouds predominantly at their early stages. The pollution-affected clouds are found to have smaller effective diameters and higher droplet number concentrations. The differences range from 10 to 40% for the effective diameter and are as high as 1000% for droplet concentration for the same vertical levels. The growth rates of droplets with altitude are slower for pollution-affected clouds (2.90 compared to 5.59 µm km ₋1), as explained by the absence of bigger droplets at the onset of cloud development. Clouds under background conditions have higher concentrations of larger droplets (>20 µm) near the cloud base, which would contribute significantly to the growth rates through the collision–coalescence process. The overall shape of the droplet size distribution (DSD) does not appear to be predominantly determined by updraught strength, especially beyond the 20 µm range. The aerosol conditions play a major role in that case. However, the updraughts modulate the DSD concentrations and are responsible for the vertical transport of water in the cloud. The larger droplets found in background clouds are associated with weak water vapour competition and a bimodal distribution of droplet sizes in the lower levels of the cloud, which enables an earlier initiation of the collision–coalescence process. This study shows that the pollution produced by Manaus significantly affects warm-phase microphysical properties of the surrounding clouds by changing the initial DSD formation. The corresponding effects on ice-phase processes and precipitation formation will be the focus of future endeavours.« less

On the initiation of lightning in thunderclouds.

PubMed

Chilingarian, Ashot; Chilingaryan, Suren; Karapetyan, Tigran; Kozliner, Lev; Khanikyants, Yeghia; Hovsepyan, Gagik; Pokhsraryan, David; Soghomonyan, Suren

2017-05-02

The relationship of lightning and elementary particle fluxes in the thunderclouds is not fully understood to date. Using the particle beams (the so-called Thunderstorm Ground Enhancements - TGEs) as a probe we investigate the characteristics of the interrelated atmospheric processes. The well-known effect of the TGE dynamics is the abrupt termination of the particle flux by the lightning flash. With new precise electronics, we can see that particle flux decline occurred simultaneously with the rearranging of the charge centers in the cloud. The analysis of the TGE energy spectra before and after the lightning demonstrates that the high-energy part of the TGE energy spectra disappeared just after lightning. The decline of particle flux coincides on millisecond time scale with first atmospheric discharges and we can conclude that Relativistic Runaway Electron Avalanches (RREA) in the thundercloud assist initiation of the negative cloud to ground lightning. Thus, RREA can provide enough ionization to play a significant role in the unleashing of the lightning flash.

Local Cloudiness Development Forecast Based on Simulation of Solid Phase Formation Processes in the Atmosphere

NASA Astrophysics Data System (ADS)

Barodka, Siarhei; Kliutko, Yauhenia; Krasouski, Alexander; Papko, Iryna; Svetashev, Alexander; Turishev, Leonid

2013-04-01

Nowadays numerical simulation of thundercloud formation processes is of great interest as an actual problem from the practical point of view. Thunderclouds significantly affect airplane flights, and mesoscale weather forecast has much to contribute to facilitate the aviation forecast procedures. An accurate forecast can certainly help to avoid aviation accidents due to weather conditions. The present study focuses on modelling of the convective clouds development and thunder clouds detection on the basis of mesoscale atmospheric processes simulation, aiming at significantly improving the aeronautical forecast. In the analysis, the primary weather radar information has been used to be further adapted for mesoscale forecast systems. Two types of domains have been selected for modelling: an internal one (with radius of 8 km), and an external one (with radius of 300 km). The internal domain has been directly applied to study the local clouds development, and the external domain data has been treated as initial and final conditions for cloud cover formation. The domain height has been chosen according to the civil aviation forecast data (i.e. not exceeding 14 km). Simulations of weather conditions and local clouds development have been made within selected domains with the WRF modelling system. In several cases, thunderclouds are detected within the convective clouds. To specify the given category of clouds, we employ a simulation technique of solid phase formation processes in the atmosphere. Based on modelling results, we construct vertical profiles indicating the amount of solid phase in the atmosphere. Furthermore, we obtain profiles demonstrating the amount of ice particles and large particles (hailstones). While simulating the processes of solid phase formation, we investigate vertical and horizontal air flows. Consequently, we attempt to separate the total amount of solid phase into categories of small ice particles, large ice particles and hailstones. Also, we strive to reveal and differentiate the basic atmospheric parameters of sublimation and coagulation processes, aiming to predict ice particles precipitation. To analyze modelling results we apply the VAPOR three-dimensional visualization package. For the chosen domains, a diurnal synoptic situation has been simulated, including rain, sleet, ice pellets, and hail. As a result, we have obtained a large scope of data describing various atmospheric parameters: cloud cover, major wind components, basic levels of isobaric surfaces, and precipitation rate. Based on this data, we show both distinction in precipitation formation due to various heights and its differentiation of the ice particles. The relation between particle rise in the atmosphere and its size is analyzed: at 8-10 km altitude large ice particles, resulted from coagulation, dominate, while at 6-7 km altitude one can find snow and small ice particles formed by condensation growth. Also, mechanical trajectories of solid precipitation particles for various ice formation processes have been calculated.

A New Search for Carbon Monoxide Absorption in the Transmission Spectrum of the Extrasolar Planet HD 209458b

NASA Astrophysics Data System (ADS)

Deming, Drake; Brown, Timothy M.; Charbonneau, David; Harrington, Joseph; Richardson, L. Jeremy

2005-04-01

We have revisited the search for carbon monoxide absorption features in transmission during the transit of the extrasolar planet HD 209458b. In 2002 August-September we acquired a total of 1077 high-resolution spectra (λ/δλ~25,000) in the K-band (2 μm) wavelength region using NIRSPEC on the Keck II telescope during three transits. These data are more numerous and of better quality than the data analyzed in an initial search by Brown et al. Our analysis achieves a sensitivity sufficient to test the degree of CO absorption in the first-overtone bands during transit on the basis of plausible models of the planetary atmosphere. We analyze our observations by comparison with theoretical tangent geometry absorption spectra, computed by adding height-invariant ad hoc temperature perturbations to the model atmosphere of Sudarsky et al. and by treating cloud height as an adjustable parameter. We do not detect CO absorption. The strong 2-0 R-branch lines between 4320 and 4330 cm-1 have depths during transit less than 1.6 parts in 104 in units of the stellar continuum (3 σ limit) at a spectral resolving power of 25,000. Our analysis indicates a weakening similar to that found in the case of sodium, suggesting that a general masking mechanism is at work in the planetary atmosphere. Under the interpretation that this masking is provided by high clouds, our analysis defines the maximum cloud-top pressure (i.e., minimum height) as a function of the model atmospheric temperature. For the relatively hot model used by Charbonneau et al. to interpret their sodium detection, our CO limit requires cloud tops at or above 3.3 mbar, and these clouds must be opaque at a wavelength of 2 μm. High clouds comprised of submicron-sized particles are already present in some models but may not provide sufficient opacity to account for our CO result. Cooler model atmospheres, having smaller atmospheric scale heights and lower CO mixing ratios, may alleviate this problem to some extent. However, even models 500 K cooler than the Sudarsky et al. model require clouds above the 100 mbar level to be consistent with our observations. Our null result therefore requires clouds to exist at an observable level in the atmosphere of HD 209458b, unless this planet is dramatically colder than current belief. Data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

THE INFLUENCE OF NONUNIFORM CLOUD COVER ON TRANSIT TRANSMISSION SPECTRA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Line, Michael R.; Parmentier, Vivien, E-mail: mrline@ucsc.edu

2016-03-20

We model the impact of nonuniform cloud cover on transit transmission spectra. Patchy clouds exist in nearly every solar system atmosphere, brown dwarfs, and transiting exoplanets. Our major findings suggest that fractional cloud coverage can exactly mimic high mean molecular weight atmospheres and vice versa over certain wavelength regions, in particular, over the Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3) bandpass (1.1–1.7 μm). We also find that patchy cloud coverage exhibits a signature that is different from uniform global clouds. Furthermore, we explain analytically why the “patchy cloud-high mean molecular weight” degeneracy exists. We also explore the degeneracy ofmore » nonuniform cloud coverage in atmospheric retrievals on both synthetic and real planets. We find from retrievals on a synthetic solar composition hot Jupiter with patchy clouds and a cloud-free high mean molecular weight warm Neptune that both cloud-free high mean molecular weight atmospheres and partially cloudy atmospheres can explain the data equally well. Another key finding is that the HST WFC3 transit transmission spectra of two well-observed objects, the hot Jupiter HD 189733b and the warm Neptune HAT-P-11b, can be explained well by solar composition atmospheres with patchy clouds without the need to invoke high mean molecular weight or global clouds. The degeneracy between high molecular weight and solar composition partially cloudy atmospheres can be broken by observing the molecular Rayleigh scattering differences between the two. Furthermore, the signature of partially cloudy limbs also appears as a ∼100 ppm residual in the ingress and egress of the transit light curves, provided that the transit timing is known to seconds.« less

DC-8 scanning lidar characterization of aircraft contrails and cirrus clouds

NASA Technical Reports Server (NTRS)

Nielsen, Norman B.; Uthe, Edward E. (Principal Investigator)

1996-01-01

A Subsonic Assessment (SASS) element of the overall Atmospheric Effects of Aviation Project (AEAP) was initiated by NASA to assess the atmospheric impact of subsonic aircraft. SRI was awarded a project to develop and test a scanning backscatter lidar for installation on the NASA DC-8 (year 1), participate in the Subsonic Aircraft: Contrail and Cloud Effects Special Study (SUCCESS) field program (year 2), and conduct a comprehensive analysis of field data (year 3). A scanning mirror pod attached to the DC-8 aircraft provides for scanning lidar observations ahead of the DC-8 and fixed-angle upward or downward observations. The lidar system installed within the DC-8 transmits 275 MJ at 1.06 gm wavelength or about 130 mJ at 1.06 and 0.53 gm simultaneously. Range-resolved aerosol backscatter is displayed in real time in terms of cloud/contrail spatial distributions. The objectives of the project are to map contrail/cloud vertical distributions ahead of DC-8; provide DC-8 guidance into enhanced scattering layers; document DC-8 flight path intersection of contrail and cloud geometries (in-situ measurement positions relative to cloud/contrail shape and an extension of in-situ measurements into the vertical -- integrated contrail/cloud properties); analyze contrail/cloud radiative properties with LIRAD (combined lidar and radiometry) technique; evaluate mean particle sizes of aircraft emissions from two-wavelength observations; study contrail/cloud interactions, diffusion, and mass decay/growth; and make observations in the near-field of aircraft engine emissions. The scanning mirror pod may also provide a scanning capability for other remote sensing instruments.

Separating Atmospheric and Surface Contributions in Hyperspectral Imager for the Coastal Ocean (HICO) Scenes using Informed Non-Negative Matrix Factorization

NASA Astrophysics Data System (ADS)

Wright, L.; Coddington, O.; Pilewskie, P.

2016-12-01

Hyperspectral instruments are a growing class of Earth observing sensors designed to improve remote sensing capabilities beyond discrete multi-band sensors by providing tens to hundreds of continuous spectral channels. Improved spectral resolution, range and radiometric accuracy allow the collection of large amounts of spectral data, facilitating thorough characterization of both atmospheric and surface properties. These new instruments require novel approaches for processing imagery and separating surface and atmospheric signals. One approach is numerical source separation, which allows the determination of the underlying physical causes of observed signals. Improved source separation will enable hyperspectral imagery to better address key science questions relevant to climate change, including land-use changes, trends in clouds and atmospheric water vapor, and aerosol characteristics. We developed an Informed Non-negative Matrix Factorization (INMF) method for separating atmospheric and surface sources. INMF offers marked benefits over other commonly employed techniques including non-negativity, which avoids physically impossible results; and adaptability, which tailors the method to hyperspectral source separation. The INMF algorithm is adapted to separate contributions from physically distinct sources using constraints on spectral and spatial variability, and library spectra to improve the initial guess. We also explore methods to produce an initial guess of the spatial separation patterns. Using this INMF algorithm we decompose hyperspectral imagery from the NASA Hyperspectral Imager for the Coastal Ocean (HICO) with a focus on separating surface and atmospheric signal contributions. HICO's coastal ocean focus provides a dataset with a wide range of atmospheric conditions, including high and low aerosol optical thickness and cloud cover, with only minor contributions from the ocean surfaces in order to isolate the contributions of the multiple atmospheric sources.

3D Simulations of methane convective storms on Titan's atmosphere

NASA Astrophysics Data System (ADS)

Hueso, R.; Sánchez-Lavega, A.

2005-08-01

The arrival of the Cassini/Huygens mission to Titan has opened an unprecedented opportunity to study the atmosphere of this satellite. Under the pressure-temperature conditions on Titan, methane, a large atmospheric component amounting perhaps to a 3-5% of the atmosphere, is close to its triple point, potentially playing a similar role as water on Earth. The Huygens probe has shown a terrain shaped by erosion of probably liquid origin, suggestive of past rain. On the other hand, Voyager IRIS spectroscopic observations of Titan imply a saturated atmosphere of methane (amounting perhaps to 150 covered by methane clouds, if we think on Earth meteorology. However, observations from Earth and Cassini have shown that clouds are localized, transient and fast evolving, in particular in the South Pole (currently in its summer season). This might imply a lack of widespread presence on Titan of nuclei where methane could initiate condensation and particle growth with subsequent precipitation. We investigate different scenarios of moist convective storms on Titan using a complete 3D atmospheric model that incorporates a full microphysics treatment required to study cloud formation processes under a saturated atmosphere with low concentration of condensation nuclei. We study local convective development under a variety of atmospheric conditions: sub-saturation, super-saturation, abundances of condensation nuclei fall, condensation nuclei lifted from the ground or gently falling from the stratosphere. We show that under the appropriate circumstances, precipitation rates comparable to typical tropical storms on Earth can be found. Acknowledgements: This work has been funded by Spanish MCYT PNAYA2003-03216, fondos FEDER and Grupos UPV 15946/2004. R. Hueso acknowledges a post-doc fellowship from Gobierno Vasco.

Infrared experiments for spaceborne planetary atmospheres research. Full report

NASA Technical Reports Server (NTRS)

1981-01-01

The role of infrared sensing in atmospheric science is discussed and existing infrared measurement techniques are reviewed. Proposed techniques for measuring planetary atmospheres are criticized and recommended instrument developments for spaceborne investigations are summarized for the following phenomena: global and local radiative budget; radiative flux profiles; winds; temperature; pressure; transient and marginal atmospheres; planetary rotation and global atmospheric activity; abundances of stable constituents; vertical, lateral, and temporal distribution of abundances; composition of clouds and aerosols; radiative properties of clouds and aerosols; cloud microstructure; cloud macrostructure; and non-LTE phenomena.

Volcanic Ash Data Assimilation System for Atmospheric Transport Model

NASA Astrophysics Data System (ADS)

Ishii, K.; Shimbori, T.; Sato, E.; Tokumoto, T.; Hayashi, Y.; Hashimoto, A.

2017-12-01

The Japan Meteorological Agency (JMA) has two operations for volcanic ash forecasts, which are Volcanic Ash Fall Forecast (VAFF) and Volcanic Ash Advisory (VAA). In these operations, the forecasts are calculated by atmospheric transport models including the advection process, the turbulent diffusion process, the gravitational fall process and the deposition process (wet/dry). The initial distribution of volcanic ash in the models is the most important but uncertain factor. In operations, the model of Suzuki (1983) with many empirical assumptions is adopted to the initial distribution. This adversely affects the reconstruction of actual eruption plumes.We are developing a volcanic ash data assimilation system using weather radars and meteorological satellite observation, in order to improve the initial distribution of the atmospheric transport models. Our data assimilation system is based on the three-dimensional variational data assimilation method (3D-Var). Analysis variables are ash concentration and size distribution parameters which are mutually independent. The radar observation is expected to provide three-dimensional parameters such as ash concentration and parameters of ash particle size distribution. On the other hand, the satellite observation is anticipated to provide two-dimensional parameters of ash clouds such as mass loading, top height and particle effective radius. In this study, we estimate the thickness of ash clouds using vertical wind shear of JMA numerical weather prediction, and apply for the volcanic ash data assimilation system.

The Atmosphere and Climate of Venus

NASA Astrophysics Data System (ADS)

Bullock, M. A.; Grinspoon, D. H.

Venus lies just sunward of the inner edge of the Sun's habitable zone. Liquid water is not stable. Like Earth and Mars, Venus probably accreted at least an ocean's worth of water, although there are alternative scenarios. The loss of this water led to the massive, dry CO2 atmosphere, extensive H2SO4 clouds (at least some of the time), and an intense CO2 greenhouse effect. This chapter describes the current understanding of Venus' atmosphere, established from the data of dozens of spacecraft and atmospheric probe missions since 1962, and by telescopic observations since the nineteenth century. Theoretical work to model the temperature, chemistry, and circulation of Venus' atmosphere is largely based on analogous models developed in the Earth sciences. We discuss the data and modeling used to understand the temperature structure of the atmosphere, as well as its composition, cloud structure, and general circulation. We address what is known and theorized about the origin and early evolution of Venus' atmosphere. It is widely understood that Venus' dense CO2 atmosphere is the ultimate result of the loss of an ocean to space, but the timing of major transitions in Venus' climate is very poorly constrained by the available data. At present, the bright clouds allow only 20% of the sunlight to drive the energy balance and therefore determine conditions at Venus' surface. Like Earth and Mars, differential heating between the equator and poles drives the atmospheric circulation. Condensable species in the atmosphere create clouds and hazes that drive feedbacks that alter radiative forcing. Also in common with Earth and Mars, the loss of light, volatile elements to space produces long-term changes in composition and chemistry. As on Earth, geologic processes are most likely modifying the atmosphere and clouds by injecting gases from volcanos as well as directly through chemical reactions with the surface. The sensitivity of Venus' atmospheric energy balance is quantified in this chapter in terms of the initial forcing due to a perturbation, radiative response, and indirect responses, which are feedbacks — either positive or negative. When applied to one Venus climate model, we found that the albedo-radiative feedback is more important than greenhouse forcing for small changes in atmospheric H2O and SO2. An increase in these gases cools the planet by making the clouds brighter. On geologic timescales the reaction of some atmospheric species (SO2, CO, OCS, S, H2O, H2S, HCl, HF) with surface minerals could cause significant changes in atmospheric composition. Laboratory data and thermochemical modeling have been important for showing that atmospheric SO2 would be depleted in ~10 m.y. if carbonates are available at the surface. Without replenishment, the clouds would disappear. Alternatively, the oxidation of pyrite could add SO2 to the atmosphere while producing stable Fe oxides at the surface. The correlation of near-infrared high emissivity (dark) surface features with three young, large volcanos on Venus is strong evidence for recent volcanic activity at these sites, certainly over the timescale necessary to support the clouds. We address the nature of heterogeneous reactions with the surface and the implications for climate change on Venus. Chemical and mineralogical signatures of past climates must exist at the surface and below, so in situ experiments on the composition of surface layers are vital for reconstructing Venus' past climate. Many of the most Earth-like planets found around other stars will probably resemble Venus or a younger version of Venus. We finish the chapter with discussing what Venus can tell us about life in the universe, since it is an example of a planetary climate rendered uninhabitable. It also resembles our world's likely future. As with the climate history of Venus, however, the timing of predictable climate transitions on the Earth is poorly constrained by the data.

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,

Plasma Clouds and Snowplows: Bulk Plasma Escape from Mars Observed by MAVEN

NASA Technical Reports Server (NTRS)

Halekas, J. S.; Brain, D. A.; Ruhunusiri, S.; McFadden, J. P.; Mitchell, D. L.; Mazelle, C.; Connerney, J. E. P.; Harada, Y.; Hara, T.; Espley, J. R.;

Absorption of Sunlight by Water Vapor in Cloudy Conditions: A Partial Explanation for the Cloud Absorption Anomaly

NASA Technical Reports Server (NTRS)

Crisp, D.

1997-01-01

The atmospheric radiative transfer algorithms used in most global general circulation models underestimate the globally-averaged solar energy absorbed by cloudy atmospheres by up to 25 W/sq m. The origin of this anomalous absorption is not yet known, but it has been attributed to a variety of sources including oversimplified or missing physical processes in these models, uncertainties in the input data, and even measurement errors. Here, a sophisticated atmospheric radiative transfer model was used to provide a more comprehensive description of the physical processes that contribute to the absorption of solar radiation by the Earth's atmosphere. We found that the amount of sunlight absorbed by a cloudy atmosphere is inversely proportional to the solar zenith angle and the cloud top height, and directly proportional to the cloud optical depth and the water vapor concentration within the clouds. Atmospheres with saturated, optically-thick, low clouds absorbed about 12 W/sq m more than clear atmospheres. This accounts for about 1/2 to 1/3 of the anomalous ab- sorption. Atmospheres with optically thick middle and high clouds usually absorb less than clear atmospheres. Because water vapor is concentrated within and below the cloud tops, this absorber is most effective at small solar zenith angles. An additional absorber that is distributed at or above the cloud tops is needed to produce the amplitude and zenith angle dependence of the observed anomalous absorption.

The Role of CO2 Clouds on the Stability of the Early Mars Atmosphere Against Collapse

NASA Astrophysics Data System (ADS)

Kahre, Melinda A.; Haberle, Robert; Steakley, Kathryn; Murphy, Jim; Kling, Alexandre

2017-10-01

The early Mars atmosphere was likely significantly more massive than it is today, given the growing body of evidence that liquid water flowed on the surface early in the planet’s history. Although the CO2 inventory was likely larger in the past, there is much we still do not understand about the state of that CO2. As surface pressure increases, the temperature at which CO2 condenses also increases, making it more likely that CO2 ice would form and persist on the surface when the atmospheric mass increases. An atmosphere that is stable against collapse must contain enough energy, distributed globally, to prohibit the formation of permanents CO2 ice reservoirs that lead to collapse. The presence of the “faint young sun” compounds this issue. Previous global climate model (GCM) investigations show that atmospheres within specific ranges of obliquities and atmospheric masses are stable against collapse. We use the NASA Ames Mars GCM to expand on these works by focusing specifically on the role of CO2 clouds in atmospheric stability. Two end member simulations are executed, one that includes CO2 cloud formation and one that does not. The simulation that explicitly includes CO2 clouds is stable, while the simulation without CO2 clouds collapses into permanent surface CO2 reservoirs. In both cases, significant atmospheric condensation is occurring in the atmosphere throughout the year. In the case without CO2 clouds, all atmospheric condensation (even if it occurs at altitude) leads directly to the accumulation of surface ice, whereas in the case with CO2 clouds, there is a finite settling timescale for the cloud particles. Depending on this timescale and the local conditions, the cloud particles could stay aloft or sublimate as they fall toward the surface. Thus, the striking difference between these two cases illustrates the important role of CO2 clouds. We plan to conduct and present further simulations to better understand how atmospheric stability depends on the details of CO2 cloud microphysical processes and assumptions.

Simulation of seasonal cloud forcing anomalies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Randall, D.A.

1990-08-01

One useful way to classify clouds is according to the processes that generate them. There are three main cloud-formation agencies: deep convection; surface evaporation; large-scale lifting in the absence of conditional instability. Although traditionally clouds have been viewed as influencing the atmospheric general circulation primarily through the release of latent heat, the atmospheric science literature contains abundant evidence that, in reality, clouds influence the general circulation through four more or less equally important effects: interactions with the solar and terrestrial radiation fields; condensation and evaporation; precipitation; small-scale circulations within the atmosphere. The most advanced of the current generation of GCMsmore » include parameterizations of all four effects. Until recently there has been lingering skepticism, in the general circulation modeling community, that the radiative effects of clouds significantly influence the atmospheric general circulation. GCMs have provided the proof that the radiative effects of clouds are important for the general circulation of the atmosphere. An important concept in analysis of the effects of clouds on climate is the cloud radiative forcing (CRF), which is defined as the difference between the radiative flux which actually occurs in the presence of clouds, and that which would occur if the clouds were removed but the atmospheric state were otherwise unchanged. We also use the term CRF to denote warming or cooling tendencies due to cloud-radiation interactions. Cloud feedback is the change in CRF that accompanies a climate change. The present study concentrates on the planetary CRF and its response to external forcing, i.e. seasonal change.« less

Hurricane Irma's Cloud Structure as Seen by NASA's AIRS

NASA Image and Video Library

2017-09-08

The large-scale structure of clouds in and around Hurricane Irma is seen in this animation and still image created with data from the Atmospheric Infrared Sounder (AIRS) instrument on NASA's Aqua satellite. The clouds are typical of tropical areas both nearby and away from tropical cyclones. Observations were taken at 1 p.m. EDT (5 p.m. UTC) on Tuesday, Sept. 5, 2017, as Irma approached the Caribbean islands and was just becoming a powerful Category 5 storm. Each cylinder represents a volume of cloud detected by AIRS. The oval cylinder ends represent a region viewed by AIRS, with the oval sizes adjusted to reflect the proportion of clouds filling the area viewed. The largest ovals are about 30 miles (45 kilometers) across. The height of the cylinders indicates the cloud thickness, with thickest clouds reaching down to the surface. The vertical scale is exaggerated 15 times. Colors represent temperatures at the tops of the clouds. The perspective views the storm diagonally from above with an initial view toward the north-northwest, with the perspective rotating clockwise for a full circle. The area depicted is about 1,000 miles by 800 miles across (1,600 by 1,300 kilometers). At the start of the loop, North America is seen at the top of the image, and coastal Venezuela at the lower right. In the initial perspective, cirrus clouds (thin and blue), associated with flow outward from the top of the hurricane, overlie warmer (pink and red) shallow clouds. About five seconds into the loop, the deep clouds in the middle of Irma are easily seen. The most dangerous parts of Irma are within the region of high and cold (blue), thick clouds surrounding the central eye. The clouds are cold because they are carried to high, cold altitudes by vigorous thunderstorms within the hurricane. The eye itself is nearly cloud free, but the few clouds within it are low and warm. As the perspective shift toward the south-southeast around seven seconds into the loop, another storm system well north of Irma can be seen. It contains high, thick clouds, with more cirrus carried outward over shallow clouds. At about nine seconds, more outflow from Irma is seen, with high, thin clouds over shallow clouds once again apparent. Shortly afterward when the view is toward the southwest, yet more deep clouds and their outflowing cirrus clouds are apparent. This image depicts many of the clouds typical of the tropics even when cyclones are not present: high, cold thunderstorms pushing cirrus clouds over nearby regions containing many warm, shallow clouds. The animation also shows the structure typical of tropical cyclones around the world: very strong thunderstorms lifting clouds into cold parts of the atmosphere, with strong outflow at upper levels carrying cirrus clouds away from the storm center, and the storm organized symmetrically around a central eye. https://photojournal.jpl.nasa.gov/catalog/PIA21950

Example MODIS Global Cloud Optical and Microphysical Properties: Comparisons between Terra and Aqua

NASA Technical Reports Server (NTRS)

Hubanks, P. A.; Platnick, S.; King, M. D.; Ackerman, S. A.; Frey, R. A.

2003-01-01

MODIS observations from the NASA EOS Terra spacecraft (launched in December 1999, 1030 local time equatorial crossing) have provided a unique data set of Earth observations. With the launch of the NASA Aqua spacecraft in May 2002 (1330 local time), two MODIS daytime (sunlit) and nighttime observations are now available in a 24 hour period, allowing for some measure of diurnal variability. We report on an initial analysis of several operational global (Level-3) cloud products from the two platforms. The MODIS atmosphere Level-3 products, which include clear-sky and aerosol products in addition to cloud products, are available as three separate files providing daily, eight-day, and monthly aggregations; each temporal aggregation is spatially aggregated to a 1 degree grid. The files contain approximately 600 statisitical datasets (from simple means and standard deviations to 1 - and 2-dimensional histograms). Operational cloud products include detection (cloud fraction), cloud-top properties, and daytimeonly cloud optical thickness and particle effective radius for both water and ice clouds. We will compare example global Terra and Aqua cloud fraction, optical thickness, and effective radius aggregations.

Preliminary design for Arctic atmospheric radiative transfer experiments

NASA Technical Reports Server (NTRS)

Zak, B. D.; Church, H. W.; Stamnes, K.; Shaw, G.; Filyushkin, V.; Jin, Z.; Ellingson, R. G.; Tsay, S. C.

1995-01-01

If current plans are realized, within the next few years, an extraordinary set of coordinated research efforts focusing on energy flows in the Arctic will be implemented. All are motivated by the prospect of global climate change. SHEBA (Surface Energy Budget of the Arctic Ocean), led by the National Science Foundation (NSF) and the Office of Naval Research (ONR), involves instrumenting an ice camp in the perennial Arctic ice pack, and taking data for 12-18 months. The ARM (Atmospheric Radiation Measurement) North Slope of Alaska and Adjacent Arctic Ocean (NSA/AAO) Cloud and Radiation Testbed (CART) focuses on atmospheric radiative transport, especially in the presence of clouds. The NSA/AAO CART involves instrumenting a sizeable area on the North Slope of Alaska and adjacent waters in the vicinity of Barrow, and acquiring data over a period of about 10 years. FIRE (First ISCCP (International Satellite Cloud Climatology Program) Regional Experiment) Phase 3 is a program led by the National Aeronautics and Space Administration (NASA) which focuses on Arctic clouds, and which is coordinated with SHEBA and ARM. FIRE has historically emphasized data from airborne and satellite platforms. All three program anticipate initiating Arctic data acquisition during spring, 1997. In light of his historic opportunity, the authors discuss a strawman atmospheric radiative transfer experimental plan that identifies which features of the radiative transport models they think should be tested, what experimental data are required for each type of test, the platforms and instrumentation necessary to acquire those data, and in general terms, how the experiments could be conducted. Aspects of the plan are applicable to all three programs.

Ionisation and discharge in cloud-forming atmospheres of brown dwarfs and extrasolar planets

NASA Astrophysics Data System (ADS)

Helling, Ch; Rimmer, P. B.; Rodriguez-Barrera, I. M.; Wood, Kenneth; Robertson, G. B.; Stark, C. R.

2016-07-01

Brown dwarfs and giant gas extrasolar planets have cold atmospheres with rich chemical compositions from which mineral cloud particles form. Their properties, like particle sizes and material composition, vary with height, and the mineral cloud particles are charged due to triboelectric processes in such dynamic atmospheres. The dynamics of the atmospheric gas is driven by the irradiating host star and/or by the rotation of the objects that changes during its lifetime. Thermal gas ionisation in these ultra-cool but dense atmospheres allows electrostatic interactions and magnetic coupling of a substantial atmosphere volume. Combined with a strong magnetic field \\gg {{B}\\text{Earth}} , a chromosphere and aurorae might form as suggested by radio and x-ray observations of brown dwarfs. Non-equilibrium processes like cosmic ray ionisation and discharge processes in clouds will increase the local pool of free electrons in the gas. Cosmic rays and lighting discharges also alter the composition of the local atmospheric gas such that tracer molecules might be identified. Cosmic rays affect the atmosphere through air showers in a certain volume which was modelled with a 3D Monte Carlo radiative transfer code to be able to visualise their spacial extent. Given a certain degree of thermal ionisation of the atmospheric gas, we suggest that electron attachment to charge mineral cloud particles is too inefficient to cause an electrostatic disruption of the cloud particles. Cloud particles will therefore not be destroyed by Coulomb explosion for the local temperature in the collisional dominated brown dwarf and giant gas planet atmospheres. However, the cloud particles are destroyed electrostatically in regions with strong gas ionisation. The potential size of such cloud holes would, however, be too small and might occur too far inside the cloud to mimic the effect of, e.g. magnetic field induced star spots.

Multi-Sensor Investigation of a Regional High-Arctic Cloudy Event

NASA Astrophysics Data System (ADS)

Ivanescu, L.; O'Neill, N. T.; Blanchet, J. P.; Baibakov, K.; Chaubey, J. P.; Perro, C. W.; Duck, T. J.

2014-12-01

A regional high-Arctic cloud event observed in March, 2011 at the PEARL Observatory, near the Eureka Weather Station (80°N, 86°W), was investigated with a view to better understanding cloud formation mechanisms during the Polar night. We analysed the temporal cloud evolution with a suite of nighttime, ground-based remote sensing (RS) instruments, supplemented by radiosonde profiles and surface weather measurements. The RS suite included Raman lidar, cloud radar, a star-photometer and microwave-radiometers. In order to estimate the spatial extent and vertical variability of the cloud mass, we employed satellite-based lidar (CALIPSO) and radar (CloudSat) profiles in the regional neighbourhood of Eureka (at a latitude of 80°N, Eureka benefits from a high frequency of CALIPSO and CloudSat overpasses). The ground-based and satellite-based observations provide quantitative measurements of extensive (bulk) properties (cloud and aerosol optical depths), and intensive (per particle properties) such as aerosol and cloud particle size as well as shape, density and aggregation phase of the cloud particulates. All observations were then compared with the upper atmosphere NCEP/NCAR reanalyses in order to understand better the synoptic context of the cloud mass dynamics as a function of key meteorological parameters such as upper air temperature and water vapor circulation. Preliminary results indicated the presence of a particular type of thin ice cloud (TIC-2) associated with a deep and stable atmospheric low. A classification into small and large ice crystal size (< 40 μm and > 40 μm, respectively), identifies the clouds as TIC-1 or TIC-2. This classification is hypothesized to be associated with the nature of the aerosols (non-anthropogenic versus anthropogenic) serving as ice nuclei in their formation. Such a distinction has important implications on the initiation of precipitation, removal rate of the cloud particles and, in consequence, the radiative forcing properties on a regional basis.

Covariability in the Monthly Mean Convective and Radiative Diurnal Cycles in the Amazon

NASA Technical Reports Server (NTRS)

Dodson, Jason B.; Taylor, Patrick C.

2015-01-01

The diurnal cycle of convective clouds greatly influences the radiative energy balance in convectively active regions of Earth, through both direct presence, and the production of anvil and stratiform clouds. Previous studies show that the frequency and properties of convective clouds can vary on monthly timescales as a result of variability in the monthly mean atmospheric state. Furthermore, the radiative budget in convectively active regions also varies by up to 7 Wm-2 in convectively active regions. These facts suggest that convective clouds connect atmospheric state variability and radiation variability beyond clear sky effects alone. Previous research has identified monthly covariability between the diurnal cycle of CERES-observed top-of-atmosphere radiative fluxes and multiple atmospheric state variables from reanalysis over the Amazon region. ASVs that enhance (reduce) deep convection, such as CAPE (LTS), tend to shift the daily OLR and cloud albedo maxima earlier (later) in the day by 2-3 hr. We first test the analysis method using multiple reanalysis products for both the dry and wet seasons to further investigate the robustness of the preliminary results. We then use CloudSat data as an independent cloud observing system to further evaluate the relationships of cloud properties to variability in radiation and atmospheric states. While CERES can decompose OLR variability into clear sky and cloud effects, it cannot determine what variability in cloud properties lead to variability in the radiative cloud effects. Cloud frequency, cloud top height, and cloud microphysics all contribute to the cloud radiative effect, all of which are observable by CloudSat. In addition, CloudSat can also observe the presence and variability of deep convective cores responsible for the production of anvil clouds. We use these capabilities to determine the covariability of convective cloud properties and the radiative diurnal cycle.

Modelling of interaction of the large disrupted meteoroid with the Earth atmosphere

NASA Astrophysics Data System (ADS)

Brykina, Irina G.

2018-05-01

The model of atmospheric fragmentation of large meteoroids to the cloud of fragments is proposed. The comparison with similar models used in the literature is made. The approximate analytical solution of meteor physics equations is obtained for the mass loss of the disrupted meteoroid, the energy deposition and for the light curve normalized to the maximum brightness. This solution is applied to modelling of interaction of the Chelyabinsk meteoroid with the atmosphere. The influence of uncertainty of initial parameters of the meteoroid on characteristics of its interaction with the atmosphere is estimated. Comparison of the analytical solution with the observational data is made.

The Third Tibetan Plateau Atmospheric Scientific Experiment for Understanding the Earth-Atmosphere Coupled System

NASA Astrophysics Data System (ADS)

Zhao, P.; Xu, X.; Chen, F.; Guo, X.; Zheng, X.; Liu, L. P.; Hong, Y.; Li, Y.; La, Z.; Peng, H.; Zhong, L. Z.; Ma, Y.; Tang, S. H.; Liu, Y.; Liu, H.; Li, Y. H.; Zhang, Q.; Hu, Z.; Sun, J. H.; Zhang, S.; Dong, L.; Zhang, H.; Zhao, Y.; Yan, X.; Xiao, A.; Wan, W.; Zhou, X.

2016-12-01

The Third Tibetan Plateau atmospheric scientific experiment (TIPEX-III) was initiated jointly by the China Meteorological Administration, the National Natural Scientific Foundation, and the Chinese Academy of Sciences. This paper presents the background, scientific objectives, and overall experimental design of TIPEX-III. It was designed to conduct an integrated observation of the earth-atmosphere coupled system over the Tibetan Plateau (TP) from land surface, planetary boundary layer (PBL), troposphere, and stratosphere for eight to ten years by coordinating ground- and air-based measurement facilities for understanding spatial heterogeneities of complex land-air interactions, cloud-precipitation physical processes, and interactions between troposphere and stratosphere. TIPEX-III originally began in 2014, and is ongoing. It established multiscale land-surface and PBL observation networks over the TP and a tropospheric meteorological radiosonde network over the western TP, and executed an integrated observation mission for cloud-precipitation physical features using ground-based radar systems and aircraft campaigns and an observation task for atmospheric ozone, aerosol, and water vapor. The archive, management, and share policy of the observation data are also introduced herein. Some TIPEX-III data have been preliminarily applied to analyze the features of surface sensible and latent heat fluxes, cloud-precipitation physical processes, and atmospheric water vapor and ozone over the TP, and to improve the local precipitation forecast. Furthermore, TIPEX-III intends to promote greater scientific and technological cooperation with international research communities and broader organizations. Scientists working internationally are invited to participate in the field campaigns and to use the TIPEX-III data for their own research.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

The remote atmosphere over the Amazon can be similar to oceanic regions in terms of aerosol conditions and cloud type formations. This is especially true during the wet season. The main aerosol-related disturbances over the Amazon have both natural sources, such as dust transport from Africa, and anthropogenic sources, such as biomass burning or urban pollution. The present work considers the impacts of the latter on the microphysical properties of warm-phase clouds by analyzing observations of the interactions between the Manaus pollution plume and its surroundings, as part of the GoAmazon2014/5 Experiment. The analyzed period corresponds to the wet seasonmore » (specifically from February to March 2014 and corresponding to the first Intensive Operating Period (IOP1) of GoAmazon2014/5). The droplet size distributions reported are in the range 1 µm ≤ D ≤ 50 µm in order to capture the processes leading up to the precipitation formation. The wet season largely presents a clean background atmosphere characterized by frequent rain showers. As such, the contrast between background clouds and those affected by the Manaus pollution can be observed and detailed. The focus is on the characteristics of the initial microphysical properties in cumulus clouds predominantly at their early stages. The pollution-affected clouds are found to have smaller effective diameters and higher droplet number concentrations. The differences range from 10 to 40 % for the effective diameter and are as high as 1000% for droplet concentration for the same vertical levels. The growth rates of droplets with altitude are slower for pollution-affected clouds (2.90 compared to 5.59 µm km –1), as explained by the absence of bigger droplets at the onset of cloud development. Clouds under background conditions have higher concentrations of larger droplets (> 20 µm) near the cloud base, which would contribute significantly to the growth rates through the collision–coalescence process. The overall shape of the droplet size distribution (DSD) does not appear to be predominantly determined by updraught strength, especially beyond the 20 µm range. The aerosol conditions play a major role in that case. However, the updraughts modulate the DSD concentrations and are responsible for the vertical transport of water in the cloud. The larger droplets found in background clouds are associated with weak water vapour competition and a bimodal distribution of droplet sizes in the lower levels of the cloud, which enables an earlier initiation of the collision–coalescence process. This paper shows that the pollution produced by Manaus significantly affects warm-phase microphysical properties of the surrounding clouds by changing the initial DSD formation. The corresponding effects on ice-phase processes and precipitation formation will be the focus of future endeavors.« less

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

DOE PAGES

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

2016-06-09

The remote atmosphere over the Amazon can be similar to oceanic regions in terms of aerosol conditions and cloud type formations. This is especially true during the wet season. The main aerosol-related disturbances over the Amazon have both natural sources, such as dust transport from Africa, and anthropogenic sources, such as biomass burning or urban pollution. The present work considers the impacts of the latter on the microphysical properties of warm-phase clouds by analyzing observations of the interactions between the Manaus pollution plume and its surroundings, as part of the GoAmazon2014/5 Experiment. The analyzed period corresponds to the wet seasonmore » (specifically from February to March 2014 and corresponding to the first Intensive Operating Period (IOP1) of GoAmazon2014/5). The droplet size distributions reported are in the range 1 µm ≤ D ≤ 50 µm in order to capture the processes leading up to the precipitation formation. The wet season largely presents a clean background atmosphere characterized by frequent rain showers. As such, the contrast between background clouds and those affected by the Manaus pollution can be observed and detailed. The focus is on the characteristics of the initial microphysical properties in cumulus clouds predominantly at their early stages. The pollution-affected clouds are found to have smaller effective diameters and higher droplet number concentrations. The differences range from 10 to 40 % for the effective diameter and are as high as 1000% for droplet concentration for the same vertical levels. The growth rates of droplets with altitude are slower for pollution-affected clouds (2.90 compared to 5.59 µm km –1), as explained by the absence of bigger droplets at the onset of cloud development. Clouds under background conditions have higher concentrations of larger droplets (> 20 µm) near the cloud base, which would contribute significantly to the growth rates through the collision–coalescence process. The overall shape of the droplet size distribution (DSD) does not appear to be predominantly determined by updraught strength, especially beyond the 20 µm range. The aerosol conditions play a major role in that case. However, the updraughts modulate the DSD concentrations and are responsible for the vertical transport of water in the cloud. The larger droplets found in background clouds are associated with weak water vapour competition and a bimodal distribution of droplet sizes in the lower levels of the cloud, which enables an earlier initiation of the collision–coalescence process. This paper shows that the pollution produced by Manaus significantly affects warm-phase microphysical properties of the surrounding clouds by changing the initial DSD formation. The corresponding effects on ice-phase processes and precipitation formation will be the focus of future endeavors.« less

A Standardized Based Approach to Managing Atmosphere Studies For Wind Energy Research

NASA Astrophysics Data System (ADS)

Stephan, E.; Sivaraman, C.

2015-12-01

Atmosphere to Electrons (A2e) is a multi-year U.S. Department of Energy (DOE) research initiative targeting significant reductions in the cost of wind energy through an improved understanding of the complex physics governing wind flow into and through wind farms. Better insight into the flow physics has the potential to reduce wind farm energy losses by up to 20%, to reduce annual operational costs by hundreds of millions of dollars, and to improve project financing terms to more closely resemble traditional capital projects. The Data Archive and Portal (DAP) is a key capability of the A2e initiative. The DAP is a cloud-based distributed system known as the 'Wind Cloud' that functions as a repository for all A2e data. This data includes numerous historic and on-going field studies involving in situ and remote sensing instruments, simulations, and scientific analysis. Significantly it is the integration and sharing of these diverse data sets through the DAP that is key to meeting the goals of A2e. This cloud will be accessible via an open and easy-to navigate user interface that facilitates community data access, interaction, and collaboration. DAP management is working with the community, industry, and international standards bodies to develop standards for wind data and to capture important characteristics of all data in the Wind Cloud. Security will be provided to facilitate storage of proprietary data alongside publicly accessible data in the Wind Cloud, and the capability to generate anonymized data will be provided to facilitate using private data by non-privileged users (when appropriate). Finally, limited computing capabilities will be provided to facilitate co-located data analysis, validation, and generation of derived products in support of A2e science.

Lidar Measurements of Wind and Cloud Around Venus from an Orbiting or Floating/flying Platform

NASA Technical Reports Server (NTRS)

Singh, Upendra N.; Limaye, Sanjay; Emmitt, George D.; Refaat, Tamer F.; Kavaya, Michael J.; Yu, Jirong; Petros, Mulugeta

2015-01-01

Given the presence of clouds and haze in the upper portion of the Venus atmosphere, it is reasonable to consider a Doppler wind lidar (DWL) for making remote measurements of the 3-dimensional winds within the tops of clouds and the overlying haze layer. Assuming an orbit altitude of 250 kilometers and cloud tops at 60 kilometers (within the upper cloud layer), an initial performance assessment of an orbiting DWL was made using a numerical instrument and atmospheres model developed for both Earth and Mars. It is reasonable to expect vertical profiles of the 3-dimensional wind speed with 1 kilometer vertical resolution and horizontal spacing of 25 kilometers to several 100 kilometers depending upon the desired integration times. These profiles would begin somewhere just below the tops of the highest clouds and extend into the overlying haze layer to some to-be-determined height. Getting multiple layers of cloud returns is also possible with no negative impact on velocity measurement accuracy. The knowledge and expertise for developing coherent Doppler wind lidar technologies and techniques, for Earth related mission at NASA Langley Research Center is being leveraged to develop an appropriate system suitable for wind measurement around Venus. We are considering a fiber-laser-based lidar system of high efficiency and smaller size and advancing the technology level to meet the requirements for DWL system for Venus from an orbiting or floating/flying platform. This presentation will describe the concept, simulation and technology development plan for wind and cloud measurements on Venus.

Io: Escape and ionization of atmospheric gases

NASA Technical Reports Server (NTRS)

Smyth, W. H.

1981-01-01

Models for the Io oxygen clouds were improved to calculate the two dimensional sky plane intensity of the 1304 A emission and the 880 A emission of atomic oxygen, in addition to the 6300 A emission intensity. These three wavelength emissions are those for which observational measurements have been performed by ground based, rocket, Earth orbiting satellite and Voyager spacecraft instruments. Comparison of model results and observations suggests that an oxygen flux from Io of about 3 billion atoms sq cm sec is required for agreement. Quantitative analysis of the Io sodium cloud has focused upon the initial tasks of acquiring and preliminary evaluation of new sodium cloud and Io plasma torus data.

Atmospheric circulations required for thick high-altitude clouds and featureless transit spectra

NASA Astrophysics Data System (ADS)

Wang, H.; Wordsworth, R. D.

2017-12-01

The transmission spectra of exoplanet GJ 1214b and GJ 436b are featureless as measured by current instruments. According to the measured density of these planets, we have reason to believe these planets have atmospheres, and the spectroscopy features of the atmospheres are unexpectedly not shown in the transit spectra. An explanation is high-altitude clouds or hazes are optically thick enough to make the transit spectra flat in the current observed wavelength range. We analyze the atmospheric circulations and vertical mixing that are crucial for the possible existence of the thick high-altitude clouds. We perform a series of GCM simulations with different atmospheric compositions and planetary parameters to reveal the conditions that are required for showing featureless spectra, and study the dynamical processes. We also study the role of cloud particles with different sizes, compositions and spectral characteristics with a radiative transfer model and cloud physics models. Varying the compositions and sizes of the cloud particles results in different requirements for the atmospheric circulations.

Clouds in Super-Earth Atmospheres: Chemical Equilibrium Calculations

NASA Astrophysics Data System (ADS)

Mbarek, Rostom; Kempton, Eliza M.-R.

2016-08-01

Recent studies have unequivocally proven the existence of clouds in super-Earth atmospheres. Here we provide a theoretical context for the formation of super-Earth clouds by determining which condensates are likely to form under the assumption of chemical equilibrium. We study super-Earth atmospheres of diverse bulk composition, which are assumed to form by outgassing from a solid core of chondritic material, following Schaefer & Fegley. The super-Earth atmospheres that we study arise from planetary cores made up of individual types of chondritic meteorites. They range from highly reducing to oxidizing and have carbon to oxygen (C:O) ratios that are both sub-solar and super-solar, thereby spanning a range of atmospheric composition that is appropriate for low-mass exoplanets. Given the atomic makeup of these atmospheres, we minimize the global Gibbs free energy of formation for over 550 gases and condensates to obtain the molecular composition of the atmospheres over a temperature range of 350-3000 K. Clouds should form along the temperature-pressure boundaries where the condensed species appear in our calculation. We find that the composition of condensate clouds depends strongly on both the H:O and C:O ratios. For the super-Earth archetype GJ 1214b, KCl and ZnS are the primary cloud-forming condensates at solar composition, in agreement with previous work. However, for oxidizing atmospheres, K2SO4 and ZnO condensates are favored instead, and for carbon-rich atmospheres with super-solar C:O ratios, graphite clouds appear. For even hotter planets, clouds form from a wide variety of rock-forming and metallic species.

Chlorine-containing salts as water ice nucleating particles on Mars

NASA Astrophysics Data System (ADS)

Santiago-Materese, D. L.; Iraci, L. T.; Clapham, M. E.; Chuang, P. Y.

2018-03-01

Water ice cloud formation on Mars largely is expected to occur on the most efficient ice nucleating particle available. Salts have been observed on the Martian surface and have been known to facilitate water cloud formation on Earth. We examined heterogeneous ice nucleation onto sodium chloride and sodium perchlorate substrates under Martian atmospheric conditions, in the range of 150 to 180 K and 10-7 to 10-5 Torr water partial pressure. Sub-155 K data for the critical saturation ratio (Scrit) suggests an exponential model best describes the temperature-dependence of nucleation onset of water ice for all substrates tested. While sodium chloride does not facilitate water ice nucleation more easily than bare silicon, sodium perchlorate does support depositional nucleation at lower saturation levels than other substrates shown and is comparable to smectite-rich clay in its ability to support cloud initiation. Perchlorates could nucleate water ice at partial pressures up to 40% lower than other substrates examined to date under Martian atmospheric conditions. These findings suggest air masses on Mars containing uplifted salts such as perchlorates could form water ice clouds at lower saturation ratios than in air masses absent similar particles.

Ion-induced nucleation of pure biogenic particles.

PubMed

Kirkby, Jasper; Duplissy, Jonathan; Sengupta, Kamalika; Frege, Carla; Gordon, Hamish; Williamson, Christina; Heinritzi, Martin; Simon, Mario; Yan, Chao; Almeida, João; Tröstl, Jasmin; Nieminen, Tuomo; Ortega, Ismael K; Wagner, Robert; Adamov, Alexey; Amorim, Antonio; Bernhammer, Anne-Kathrin; Bianchi, Federico; Breitenlechner, Martin; Brilke, Sophia; Chen, Xuemeng; Craven, Jill; Dias, Antonio; Ehrhart, Sebastian; Flagan, Richard C; Franchin, Alessandro; Fuchs, Claudia; Guida, Roberto; Hakala, Jani; Hoyle, Christopher R; Jokinen, Tuija; Junninen, Heikki; Kangasluoma, Juha; Kim, Jaeseok; Krapf, Manuel; Kürten, Andreas; Laaksonen, Ari; Lehtipalo, Katrianne; Makhmutov, Vladimir; Mathot, Serge; Molteni, Ugo; Onnela, Antti; Peräkylä, Otso; Piel, Felix; Petäjä, Tuukka; Praplan, Arnaud P; Pringle, Kirsty; Rap, Alexandru; Richards, Nigel A D; Riipinen, Ilona; Rissanen, Matti P; Rondo, Linda; Sarnela, Nina; Schobesberger, Siegfried; Scott, Catherine E; Seinfeld, John H; Sipilä, Mikko; Steiner, Gerhard; Stozhkov, Yuri; Stratmann, Frank; Tomé, Antonio; Virtanen, Annele; Vogel, Alexander L; Wagner, Andrea C; Wagner, Paul E; Weingartner, Ernest; Wimmer, Daniela; Winkler, Paul M; Ye, Penglin; Zhang, Xuan; Hansel, Armin; Dommen, Josef; Donahue, Neil M; Worsnop, Douglas R; Baltensperger, Urs; Kulmala, Markku; Carslaw, Kenneth S; Curtius, Joachim

2016-05-26

Atmospheric aerosols and their effect on clouds are thought to be important for anthropogenic radiative forcing of the climate, yet remain poorly understood. Globally, around half of cloud condensation nuclei originate from nucleation of atmospheric vapours. It is thought that sulfuric acid is essential to initiate most particle formation in the atmosphere, and that ions have a relatively minor role. Some laboratory studies, however, have reported organic particle formation without the intentional addition of sulfuric acid, although contamination could not be excluded. Here we present evidence for the formation of aerosol particles from highly oxidized biogenic vapours in the absence of sulfuric acid in a large chamber under atmospheric conditions. The highly oxygenated molecules (HOMs) are produced by ozonolysis of α-pinene. We find that ions from Galactic cosmic rays increase the nucleation rate by one to two orders of magnitude compared with neutral nucleation. Our experimental findings are supported by quantum chemical calculations of the cluster binding energies of representative HOMs. Ion-induced nucleation of pure organic particles constitutes a potentially widespread source of aerosol particles in terrestrial environments with low sulfuric acid pollution.

Sources, Composition, and Properties of Newly Formed and Regional Organic Aerosol in a Boreal Forest during the Biogenic Aerosol: Effects on Clouds and Climate Field Campaign Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thornton, Joel

2016-05-01

The Thornton Laboratory participated in the U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Climate Research Facility’s Biogenic Aerosol Effects on Clouds and Climate (BAECC) campaign in Finland by deploying our mass spectrometer. We then participated in environmental simulation chamber studies at Pacific Northwest National Laboratory (PNNL). Thereafter, we analyzed the results as demonstrated in the several presentations and publications. The field campaign and initial environmental chamber studies are described below.

A Fragment-Cloud Approach for Modeling Atmospheric Breakup of Asteroids with Varied Internal Structures

NASA Astrophysics Data System (ADS)

Wheeler, Lorien; Mathias, Donovan; NASA Engineering Risk Assessment Team, NASA Asteroid Threat Assessment Project

2016-10-01

As an asteroid descends toward Earth, it deposits energy in the atmosphere through aerodynamic drag and ablation. Asteroid impact risk assessments rely on energy deposition estimates to predict blast overpressures and ground damage that may result from an airburst, such as the one that occurred over Chelyabinsk, Russia in 2013. The rates and altitudes at which energy is deposited along the entry trajectory depend upon how the bolide fragments, which in turn depends upon its internal structure and composition. In this work, an analytic asteroid fragmentation model has been developed to model the atmospheric breakup and resulting energy deposition of asteroids with a range of internal structures. The modeling approach combines successive fragmentation of larger independent pieces with aggregate debris clouds released with each fragmentation event. The model can vary the number and masses of fragments produced, the amount of mass released as debris clouds, and the size-strength scaling used to increase the robustness of smaller fragments. The initial asteroid body can be seeded with a distribution of independent fragment sizes amid a remaining debris mass to represent loose rubble pile conglomerations, or can be defined as a monolith with an outer regolith layer. This approach enables the model to represent a range of breakup behaviors and reproduce detailed energy deposition features such as multiple flares due to successive burst events, high-altitude regolith blow-off, or initial disruption of rubble piles followed by more energetic breakup of the constituent boulders. These capabilities provide a means to investigate sensitivities of ground damage to potential variations in asteroid structure.

A Lab Based Method for Exoplanet Cloud and Aerosol Characterization

NASA Astrophysics Data System (ADS)

Johnson, A. V.; Schneiderman, T. M.; Bauer, A. J. R.; Cziczo, D. J.

2017-12-01

The atmospheres of some smaller, cooler exoplanets, like GJ 1214b, lack strong spectral features. This may suggest the presence of a high, optically thick cloud layer and poses great challenges for atmospheric characterization, but there is hope. The study of extraterrestrial atmospheres with terrestrial based techniques has proven useful for understanding the cloud-laden atmospheres of our solar system. Here we build on this by leveraging laboratory-based, terrestrial cloud particle instrumentation to better understand the microphysical and radiative properties of proposed exoplanet cloud and aerosol particles. The work to be presented focuses on the scattering properties of single particles, that may be representative of those suspended in exoplanet atmospheres, levitated in an Electrodynamic Balance (EDB). I will discuss how we leverage terrestrial based cloud microphysics for exoplanet applications, the instruments for single and ensemble particle studies used in this work, our investigation of ammonium nitrate (NH4NO3) scattering across temperature dependent crystalline phase changes, and the steps we are taking toward the collection of scattering phase functions and polarization of scattered light for exoplanet cloud analogs. Through this and future studies we hope to better understand how upper level cloud and/or aerosol particles in exoplanet atmospheres interact with incoming radiation from their host stars and what atmospheric information may still be obtainable through remote observations when no spectral features are observed.

A short overview of the microbial population in clouds: Potential roles in atmospheric chemistry and nucleation processes

NASA Astrophysics Data System (ADS)

Delort, Anne-Marie; Vaïtilingom, Mickael; Amato, Pierre; Sancelme, Martine; Parazols, Marius; Mailhot, Gilles; Laj, Paolo; Deguillaume, Laurent

2010-11-01

Recent studies showed that living microorganisms, including bacteria, fungi and yeasts, are present in the atmospheric water phase (fog and clouds) and their role in chemical processes may have been underestimated. At the interface between atmospheric science and microbiology, information about this field of science suffers from the fact that not all recent findings are efficiently conveyed to both scientific communities. The purpose of this paper is therefore to provide a short overview of recent work linked to living organisms in the atmospheric water phase, from their activation to cloud droplets and ice crystal, to their potential impact on atmospheric chemical processes. This paper is focused on the microorganisms present in clouds and on the role they could play in atmospheric chemistry and nucleation processes. First, the life cycle of microorganisms via the atmosphere is examined, including their aerosolization from sources, their integration into clouds and their wet deposition on the ground. Second, special attention is paid to the possible impacts of microorganisms on liquid and ice nucleation processes. Third, a short description of the microorganisms that have been found in clouds and their variability in numbers and diversity is presented, emphasizing some specific characteristics that could favour their occurrence in cloud droplets. In the last section, the potential role of microbial activity as an alternative route to photochemical reaction pathways in cloud chemistry is discussed.

Polarized scattered light from self-luminous exoplanets. Three-dimensional scattering radiative transfer with ARTES

NASA Astrophysics Data System (ADS)

Stolker, T.; Min, M.; Stam, D. M.; Mollière, P.; Dominik, C.; Waters, L. B. F. M.

2017-11-01

Context. Direct imaging has paved the way for atmospheric characterization of young and self-luminous gas giants. Scattering in a horizontally-inhomogeneous atmosphere causes the disk-integrated polarization of the thermal radiation to be linearly polarized, possibly detectable with the newest generation of high-contrast imaging instruments. Aims: We aim to investigate the effect of latitudinal and longitudinal cloud variations, circumplanetary disks, atmospheric oblateness, and cloud particle properties on the integrated degree and direction of polarization in the near-infrared. We want to understand how 3D atmospheric asymmetries affect the polarization signal in order to assess the potential of infrared polarimetry for direct imaging observations of planetary-mass companions. Methods: We have developed a three-dimensional Monte Carlo radiative transfer code (ARTES) for scattered light simulations in (exo)planetary atmospheres. The code is applicable to calculations of reflected light and thermal radiation in a spherical grid with a parameterized distribution of gas, clouds, hazes, and circumplanetary material. A gray atmosphere approximation is used for the thermal structure. Results: The disk-integrated degree of polarization of a horizontally-inhomogeneous atmosphere is maximal when the planet is flattened, the optical thickness of the equatorial clouds is large compared to the polar clouds, and the clouds are located at high altitude. For a flattened planet, the integrated polarization can both increase or decrease with respect to a spherical planet which depends on the horizontal distribution and optical thickness of the clouds. The direction of polarization can be either parallel or perpendicular to the projected direction of the rotation axis when clouds are zonally distributed. Rayleigh scattering by submicron-sized cloud particles will maximize the polarimetric signal whereas the integrated degree of polarization is significantly reduced with micron-sized cloud particles as a result of forward scattering. The presence of a cold or hot circumplanetary disk may also produce a detectable degree of polarization (≲1%) even with a uniform cloud layer in the atmosphere.

A~comprehensive parameterization of heterogeneous ice nucleation of dust surrogate: laboratory study with hematite particles and its application to atmospheric models

NASA Astrophysics Data System (ADS)

Hiranuma, N.; Paukert, M.; Steinke, I.; Zhang, K.; Kulkarni, G.; Hoose, C.; Schnaiter, M.; Saathoff, H.; Möhler, O.

2014-06-01

A new heterogeneous ice nucleation parameterization that covers a~wide temperature range (-36 to -78 °C) is presented. Developing and testing such an ice nucleation parameterization, which is constrained through identical experimental conditions, is critical in order to accurately simulate the ice nucleation processes in cirrus clouds. The surface-scaled ice nucleation efficiencies of hematite particles, inferred by ns, were derived from AIDA (Aerosol Interaction and Dynamics in the Atmosphere) cloud chamber measurements under water subsaturated conditions that were realized by continuously changing temperature (T) and relative humidity with respect to ice (RHice) in the chamber. Our measurements showed several different pathways to nucleate ice depending on T and RHice conditions. For instance, almost T-independent freezing was observed at -60 °C < T < -50 °C, where RHice explicitly controlled ice nucleation efficiency, while both T and RHice played roles in other two T regimes: -78 °C < T < -60 °C and -50 °C < T < -36 °C. More specifically, observations at T colder than -60 °C revealed that higher RHice was necessary to maintain constant ns, whereas T may have played a significant role in ice nucleation at T warmer than -50 °C. We implemented new ns parameterizations into two cloud models to investigate its sensitivity and compare with the existing ice nucleation schemes towards simulating cirrus cloud properties. Our results show that the new AIDA-based parameterizations lead to an order of magnitude higher ice crystal concentrations and inhibition of homogeneous nucleation in colder temperature regions. Our cloud simulation results suggest that atmospheric dust particles that form ice nuclei at lower temperatures, below -36 °C, can potentially have stronger influence on cloud properties such as cloud longevity and initiation when compared to previous parameterizations.

A Comprehensive Parameterization of Heterogeneous Ice Nucleation of Dust Surrogate: Laboratory Study with Hematite Particles and Its Application to Atmospheric Models

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hiranuma, Naruki; Paukert, Marco; Steinke, Isabelle

2014-12-10

A new heterogeneous ice nucleation parameterization that covers a wide temperature range (-36 °C to -78 °C) is presented. Developing and testing such an ice nucleation parameterization, which is constrained through identical experimental conditions, is critical in order to accurately simulate the ice nucleation processes in cirrus clouds. The surface-scaled ice nucleation efficiencies of hematite particles, inferred by n s, were derived from AIDA (Aerosol Interaction and Dynamics in the Atmosphere) cloud chamber measurements under water subsaturated conditions that were realized by continuously changing temperature (T) and relative humidity with respect to ice (RH ice) in the chamber. Our measurementsmore » showed several different pathways to nucleate ice depending on T and RH ice conditions. For instance, almost independent freezing was observed at -60 °C < T < -50 °C, where RH ice explicitly controlled ice nucleation efficiency, while both T and RH ice played roles in other two T regimes: -78 °C < T < -60 °C and -50 °C < T < -36 °C. More specifically, observations at T colder than -60 °C revealed that higher RHice was necessary to maintain constant n s, whereas T may have played a significant role in ice nucleation at T warmer than -50 °C. We implemented new n s parameterizations into two cloud models to investigate its sensitivity and compare with the existing ice nucleation schemes towards simulating cirrus cloud properties. Our results show that the new AIDA-based parameterizations lead to an order of magnitude higher ice crystal concentrations and inhibition of homogeneous nucleation in colder temperature regions. Our cloud simulation results suggest that atmospheric dust particles that form ice nuclei at lower temperatures, below -36 °C, can potentially have stronger influence on cloud properties such as cloud longevity and initiation when compared to previous parameterizations.« less

The impact of atmospheric stability and wind shear on vertical cloud overlap over the Tibetan Plateau

NASA Astrophysics Data System (ADS)

Li, Jiming; Lv, Qiaoyi; Jian, Bida; Zhang, Min; Zhao, Chuanfeng; Fu, Qiang; Kawamoto, Kazuaki; Zhang, Hua

2018-05-01

Studies have shown that changes in cloud cover are responsible for the rapid climate warming over the Tibetan Plateau (TP) in the past 3 decades. To simulate the total cloud cover, atmospheric models have to reasonably represent the characteristics of vertical overlap between cloud layers. Until now, however, this subject has received little attention due to the limited availability of observations, especially over the TP. Based on the above information, the main aim of this study is to examine the properties of cloud overlaps over the TP region and to build an empirical relationship between cloud overlap properties and large-scale atmospheric dynamics using 4 years (2007-2010) of data from the CloudSat cloud product and collocated ERA-Interim reanalysis data. To do this, the cloud overlap parameter α, which is an inverse exponential function of the cloud layer separation D and decorrelation length scale L, is calculated using CloudSat and is discussed. The parameters α and L are both widely used to characterize the transition from the maximum to random overlap assumption with increasing layer separations. For those non-adjacent layers without clear sky between them (that is, contiguous cloud layers), it is found that the overlap parameter α is sensitive to the unique thermodynamic and dynamic environment over the TP, i.e., the unstable atmospheric stratification and corresponding weak wind shear, which leads to maximum overlap (that is, greater α values). This finding agrees well with the previous studies. Finally, we parameterize the decorrelation length scale L as a function of the wind shear and atmospheric stability based on a multiple linear regression. Compared with previous parameterizations, this new scheme can improve the simulation of total cloud cover over the TP when the separations between cloud layers are greater than 1 km. This study thus suggests that the effects of both wind shear and atmospheric stability on cloud overlap should be taken into account in the parameterization of decorrelation length scale L in order to further improve the calculation of the radiative budget and the prediction of climate change over the TP in the atmospheric models.

HCl in rocket exhaust clouds - Atmospheric dispersion, acid aerosol characteristics, and acid rain deposition

NASA Technical Reports Server (NTRS)

Pellett, G. L.; Sebacher, D. I.; Bendura, R. J.; Wornom, D. E.

1983-01-01

Both measurements and model calculations of the temporal dispersion of peak HCl (g + aq) concentration in Titan III exhaust clouds are found to be well characterized by one-term power-law decay expressions. The respective coefficients and decay exponents, however, are found to vary widely with meteorology. The HCl (g), HCl (g + aq), dewpoint, and temperature-pressure-altitude data for Titan III exhaust clouds are consistent with accurately calculated HCl/H2O vapor-liquid compositions for a model quasi-equilibrated flat surface aqueous aerosol. Some cloud evolution characteristics are also defined. Rapid and extensive condensation of aqueous acid clearly occurs during the first three min of cloud rise. Condensation is found to be intensified by the initial entrainment of relatively moist ambient air from lower levels, that is, from levels below eventual cloud stabilization. It is pointed out that if subsequent dilution air at stabilization altitude is significantly drier, a state of maximum condensation soon occurs, followed by an aerosol evaporation phase.

Cloudbus Toolkit for Market-Oriented Cloud Computing

NASA Astrophysics Data System (ADS)

Buyya, Rajkumar; Pandey, Suraj; Vecchiola, Christian

This keynote paper: (1) presents the 21st century vision of computing and identifies various IT paradigms promising to deliver computing as a utility; (2) defines the architecture for creating market-oriented Clouds and computing atmosphere by leveraging technologies such as virtual machines; (3) provides thoughts on market-based resource management strategies that encompass both customer-driven service management and computational risk management to sustain SLA-oriented resource allocation; (4) presents the work carried out as part of our new Cloud Computing initiative, called Cloudbus: (i) Aneka, a Platform as a Service software system containing SDK (Software Development Kit) for construction of Cloud applications and deployment on private or public Clouds, in addition to supporting market-oriented resource management; (ii) internetworking of Clouds for dynamic creation of federated computing environments for scaling of elastic applications; (iii) creation of 3rd party Cloud brokering services for building content delivery networks and e-Science applications and their deployment on capabilities of IaaS providers such as Amazon along with Grid mashups; (iv) CloudSim supporting modelling and simulation of Clouds for performance studies; (v) Energy Efficient Resource Allocation Mechanisms and Techniques for creation and management of Green Clouds; and (vi) pathways for future research.

Retrieving Atmospheric Profiles Data in the Presence of Clouds from Hyperspectral Remote Sensing Data

NASA Technical Reports Server (NTRS)

Liu, Xu; Larar, Allen M.; Zhou, Daniel K.; Kizer, Susan H.; Wu, Wan; Barnet, Christopher; Divakarla, Murty; Guo, Guang; Blackwell, Bill; Smith, William L.;

Ultraspectral sounding retrieval error budget and estimation

NASA Astrophysics Data System (ADS)

Zhou, Daniel K.; Larar, Allen M.; Liu, Xu; Smith, William L.; Strow, Larrabee L.; Yang, Ping

2011-11-01

The ultraspectral infrared radiances obtained from satellite observations provide atmospheric, surface, and/or cloud information. The intent of the measurement of the thermodynamic state is the initialization of weather and climate models. Great effort has been given to retrieving and validating these atmospheric, surface, and/or cloud properties. Error Consistency Analysis Scheme (ECAS), through fast radiative transfer model (RTM) forward and inverse calculations, has been developed to estimate the error budget in terms of absolute and standard deviation of differences in both spectral radiance and retrieved geophysical parameter domains. The retrieval error is assessed through ECAS without assistance of other independent measurements such as radiosonde data. ECAS re-evaluates instrument random noise, and establishes the link between radiometric accuracy and retrieved geophysical parameter accuracy. ECAS can be applied to measurements of any ultraspectral instrument and any retrieval scheme with associated RTM. In this paper, ECAS is described and demonstration is made with the measurements of the METOP-A satellite Infrared Atmospheric Sounding Interferometer (IASI).

Ultraspectral Sounding Retrieval Error Budget and Estimation

NASA Technical Reports Server (NTRS)

Zhou, Daniel K.; Larar, Allen M.; Liu, Xu; Smith, William L.; Strow, L. Larrabee; Yang, Ping

2011-01-01

The ultraspectral infrared radiances obtained from satellite observations provide atmospheric, surface, and/or cloud information. The intent of the measurement of the thermodynamic state is the initialization of weather and climate models. Great effort has been given to retrieving and validating these atmospheric, surface, and/or cloud properties. Error Consistency Analysis Scheme (ECAS), through fast radiative transfer model (RTM) forward and inverse calculations, has been developed to estimate the error budget in terms of absolute and standard deviation of differences in both spectral radiance and retrieved geophysical parameter domains. The retrieval error is assessed through ECAS without assistance of other independent measurements such as radiosonde data. ECAS re-evaluates instrument random noise, and establishes the link between radiometric accuracy and retrieved geophysical parameter accuracy. ECAS can be applied to measurements of any ultraspectral instrument and any retrieval scheme with associated RTM. In this paper, ECAS is described and demonstration is made with the measurements of the METOP-A satellite Infrared Atmospheric Sounding Interferometer (IASI)..

Clouds Composition in Super-Earth Atmospheres: Chemical Equilibrium Calculations

NASA Astrophysics Data System (ADS)

Kempton, Eliza M.-R.; Mbarek, Rostom

2015-12-01

Attempts to determine the composition of super-Earth atmospheres have so far been plagued by the presence of clouds. Yet the theoretical framework to understand these clouds is still in its infancy. For the super-Earth archetype GJ 1214b, KCl, Na2S, and ZnS have been proposed as condensates that would form under the condition of chemical equilibrium, if the planet’s atmosphere has a bulk composition near solar. Condensation chemistry calculations have not been presented for a wider range of atmospheric bulk composition that is to be expected for super-Earth exoplanets. Here we provide a theoretical context for the formation of super-Earth clouds in atmospheres of varied composition by determining which condensates are likely to form, under the assumption of chemical equilibrium. We model super-Earth atmospheres assuming they are formed by degassing of volatiles from a solid planetary core of chondritic material. Given the atomic makeup of these atmospheres, we minimize the global Gibbs free energy of over 550 gases and condensates to obtain the molecular composition of the atmospheres over a temperature range of 350-3,000 K. Clouds should form along the temperature-pressure boundaries where the condensed species appear in our calculations. The super-Earth atmospheres that we study range from highly reducing to oxidizing and have carbon to oxygen (C:O) ratios that are both sub-solar and super-solar, thereby spanning a diverse range of atmospheric composition that is appropriate for low-mass exoplanets. Some condensates appear across all of our models. However, the majority of condensed species appear only over specific ranges of H:O and C:O ratios. We find that for GJ 1214b, KCl is the primary cloud-forming condensate at solar composition, in agreement with previous work. However, for oxidizing atmospheres, where H:O is less than unity, K2SO4 clouds form instead. For carbon-rich atmospheres with super-solar C:O ratios, graphite clouds additionally appear. At higher temperatures, clouds are formed from a variety of materials including metals, metal oxides, and aluminosilicates.

Uptake and mobilization of organic chemicals with clouds: evidence from a hail sample.

PubMed

Ma, Jianmin; Sverko, Ed; Su, Yushan; Zhang, Junhua; Gao, Hong

2013-09-03

Polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) were measured in hail samples collected during a storm that occurred on a spring morning in Toronto, Canada. The presence of these organic chemicals in hail suggests that clouds likely provide an atmospheric transport pathway for these substances in the free atmosphere. Results reported here may carry significant implications for atmospheric transport, mass balance, tropospheric cold trapping, and environmental fate of organic chemicals. Backward trajectories along with measured and modeled cloud cover show that clouds causing the hail event were formed and advected from the midwestern and southeastern United States. After being emitted to the atmosphere, the organic chemicals were likely lifted by atmospheric ascending motions to a higher atmospheric elevation and partitioned onto clouds. These clouds then carry the organic chemicals to a downwind location where they are deposited to the ground surface via precipitation. We found that the organic chemicals with high solubility and vapor pressure tend to partition into clouds through sorption to cloudwater droplets and ice particles. It was found that approximately 7-30% of pyrene could be sorbed into cloudwater droplets and ice particles in this hail event at the expense of reduced gas-phase concentrations.

Diabatic forcing and initialization with assimilation of cloud and rain water in a forecast model: Methodology

NASA Technical Reports Server (NTRS)

Raymond, William H.; Olson, William S.; Callan, Geary

1990-01-01

The focus of this part of the investigation is to find one or more general modeling techniques that will help reduce the time taken by numerical forecast models to initiate or spin-up precipitation processes and enhance storm intensity. If the conventional data base could explain the atmospheric mesoscale flow in detail, then much of our problem would be eliminated. But the data base is primarily synoptic scale, requiring that a solution must be sought either in nonconventional data, in methods to initialize mesoscale circulations, or in ways of retaining between forecasts the model generated mesoscale dynamics and precipitation fields. All three methods are investigated. The initialization and assimilation of explicit cloud and rainwater quantities computed from conservation equations in a mesoscale regional model are examined. The physical processes include condensation, evaporation, autoconversion, accretion, and the removal of rainwater by fallout. The question of how to initialize the explicit liquid water calculations in numerical models and how to retain information about precipitation processes during the 4-D assimilation cycle are important issues that are addressed. The explicit cloud calculations were purposely kept simple so that different initialization techniques can be easily and economically tested. Precipitation spin-up processes associated with three different types of weather phenomena are examined. Our findings show that diabatic initialization, or diabatic initialization in combination with a new diabatic forcing procedure, work effectively to enhance the spin-up of precipitation in a mesoscale numerical weather prediction forecast. Also, the retention of cloud and rain water during the analysis phase of the 4-D data assimilation procedure is shown to be valuable. Without detailed observations, the vertical placement of the diabatic heating remains a critical problem.

Stereographic observations from geosynchronous satellites - An important new tool for the atmospheric sciences

NASA Technical Reports Server (NTRS)

Hasler, A. F.

1981-01-01

Observations of cloud geometry using scan-synchronized stereo geostationary satellites having images with horizontal spatial resolution of approximately 0.5 km, and temporal resolution of up to 3 min are presented. The stereo does not require a cloud with known emissivity to be in equilibrium with an atmosphere with a known vertical temperature profile. It is shown that absolute accuracies of about 0.5 km are possible. Qualitative and quantitative representations of atmospheric dynamics were shown by remapping, display, and stereo image analysis on an interactive computer/imaging system. Applications of stereo observations include: (1) cloud top height contours of severe thunderstorms and hurricanes, (2) cloud top and base height estimates for cloud-wind height assignment, (3) cloud growth measurements for severe thunderstorm over-shooting towers, (4) atmospheric temperature from stereo heights and infrared cloud top temperatures, and (5) cloud emissivity estimation. Recommendations are given for future improvements in stereo observations, including a third GOES satellite, operational scan synchronization of all GOES satellites and better resolution sensors.

Proceedings of a Workshop on Polar Stratospheric Clouds: Their Role in Atmospheric Processes

NASA Technical Reports Server (NTRS)

Hamill, P. (Editor); Mcmaster, L. R. (Editor)

1984-01-01

The potential role of polar stratospheric clouds in atmospheric processes was assessed. The observations of polar stratospheric clouds with the Nimbus 7 SAM II satellite experiment were reviewed and a preliminary analysis of their formation, impact on other remote sensing experiments, and potential impact on climate were presented. The potential effect of polar stratospheric clouds on climate, radiation balance, atmospheric dynamics, stratospheric chemistry and water vapor budget, and cloud microphysics was assessed. Conclusions and recommendations, a synopsis of materials and complementary material to support those conclusions and recommendations are presented.

CLOUDS IN SUPER-EARTH ATMOSPHERES: CHEMICAL EQUILIBRIUM CALCULATIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mbarek, Rostom; Kempton, Eliza M.-R., E-mail: mbarekro@grinnell.edu, E-mail: kemptone@grinnell.edu

Recent studies have unequivocally proven the existence of clouds in super-Earth atmospheres. Here we provide a theoretical context for the formation of super-Earth clouds by determining which condensates are likely to form under the assumption of chemical equilibrium. We study super-Earth atmospheres of diverse bulk composition, which are assumed to form by outgassing from a solid core of chondritic material, following Schaefer and Fegley. The super-Earth atmospheres that we study arise from planetary cores made up of individual types of chondritic meteorites. They range from highly reducing to oxidizing and have carbon to oxygen (C:O) ratios that are both sub-solarmore » and super-solar, thereby spanning a range of atmospheric composition that is appropriate for low-mass exoplanets. Given the atomic makeup of these atmospheres, we minimize the global Gibbs free energy of formation for over 550 gases and condensates to obtain the molecular composition of the atmospheres over a temperature range of 350–3000 K. Clouds should form along the temperature–pressure boundaries where the condensed species appear in our calculation. We find that the composition of condensate clouds depends strongly on both the H:O and C:O ratios. For the super-Earth archetype GJ 1214b, KCl and ZnS are the primary cloud-forming condensates at solar composition, in agreement with previous work. However, for oxidizing atmospheres, K{sub 2}SO{sub 4} and ZnO condensates are favored instead, and for carbon-rich atmospheres with super-solar C:O ratios, graphite clouds appear. For even hotter planets, clouds form from a wide variety of rock-forming and metallic species.« less

Testing the Role of Impacts in Warming Early Mars: Comparisons Between 1-D and GCM Results

NASA Astrophysics Data System (ADS)

Steakley, K.; Kahre, M. A.; Murphy, J. R.; Haberle, R. M.; Kling, A.

2017-12-01

Comet and asteroid impacts have been explored as a potential mechanism for producing warmer and wetter conditions for early Mars and possibly contributing to valley network formation. However, criticisms have been made regarding the timing of large impacts compared to valley network activity and the ability of such impacts to induce long lasting climate changes and the appropriate amount of precipitation. We test the impact heating hypothesis for the late Noachian Mars atmosphere by revisiting the scenarios described in Segura et al. (2008, JGR Planets 113, E11007) with a 3D global climate model (GCM). Segura et al. (2008) showed with a 1-D model that impacts ranging 30-100 km in diameter could in certain cases induce months to years of above-freezing temperatures and tens of cm to meters of rainfall in atmospheres with 150-mbar, 1-bar, or 2-bar surface pressures. We impose the same initial conditions into the Ames Research Center Mars GCM with updated water cycle physics that includes bulk cloud formation, sedimentation, precipitation (liquid or snow), a Manabe moist convection scheme, and the radiative effects of both liquid and ice clouds. Initial conditions in the GCM match those described in Segura et al. (2008) as closely as possible and include a hot post-impact debris layer, a warm atmosphere, and water vapor profiles consistent with the water abundances mobilized by the impact. Scenarios with 30-, 50- and 100- km impactors in 150-mbar, 1-bar, and 2-bar surface pressure cases are explored both with and without radiatively active water clouds. Our goals are to determine how global rainfall totals and global surface temperatures from the GCM compare with the simpler 1-D Segura et al. (2008) model, to examine what rainfall patterns emerge in the GCM and how they compare to the observed valley network distribution, and to more carefully assess the role of cloud microphysics and radiative effects on the duration and intensity of post-impact climates.

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

NASA Astrophysics Data System (ADS)

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

2017-04-01

There are multiple factors which affect the micro- and macrophysical properties of clouds, including the atmospheric vertical structure and dominant meteorological conditions in addition to aerosol concentration, all of which may be coupled to one another. In the quest to determine aerosol effects on clouds, these potential relationships must be understood. As bio- and fossil fuel combustion has increased in southeast Asia, corresponding increases in atmospheric aerosol pollution have been seen over the surrounding regions. These emissions notably include black carbon (BC) aerosols, which absorb rather than reflect solar radiation, affecting the atmosphere over the Indian Ocean through direct warming in addition to modifying cloud microphysical properties. The CARDEX (Cloud, Aerosol, Radiative forcing, Dynamics EXperiment) field campaign was conducted during the winter monsoon season (February and March) of 2012 in the northern Indian Ocean, a region dominated by trade cumulus clouds. During CARDEX, small unmanned aircraft were deployed, measuring aerosol, radiation, cloud, water vapor fluxes, and meteorological properties while a surface observatory collected continuous measurements of atmospheric precipitable water vapor (PWV), water vapor fluxes, surface and total-column aerosol, and cloud liquid water path (LWP). We present observations which indicate a positive correlation between aerosol and cloud LWP only when considering cases with low atmospheric water vapor (PWV)

Aqueous Processing of Atmospheric Organic Particles in Cloud Water Collected via Aircraft Sampling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boone, Eric J.; Laskin, Alexander; Laskin, Julia

2015-07-21

Cloud water and below-cloud atmospheric particle samples were collected onboard a research aircraft during the Southern Oxidant and Aerosol Study (SOAS) over a forested region of Alabama in June 2013. The organic molecular composition of the samples was studied to gain insights into the aqueous-phase processing of organic compounds within cloud droplets. High resolution mass spectrometry with nanospray desorption electrospray ionization and direct infusion electrospray ionization were utilized to compare the organic composition of the particle and cloud water samples, respectively. Isoprene and monoterpene-derived organosulfates and oligomers were identified in both the particles and cloud water, showing the significant influencemore » of biogenic volatile organic compound oxidation above the forested region. While the average O:C ratios of the organic compounds were similar between the atmospheric particle and cloud water samples, the chemical composition of these samples was quite different. Specifically, hydrolysis of organosulfates and formation of nitrogen-containing compounds were observed for the cloud water when compared to the atmospheric particle samples, demonstrating that cloud processing changes the composition of organic aerosol.« less

A study of cloud microphysics and precipitation over the Tibetan Plateau by radar observations and cloud-resolving model simulations: Cloud Microphysics over Tibetan Plateau

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gao, Wenhua; Sui, Chung-Hsiung; Fan, Jiwen

Cloud microphysical properties and precipitation over the Tibetan Plateau (TP) are unique because of the high terrains, clean atmosphere, and sufficient water vapor. With dual-polarization precipitation radar and cloud radar measurements during the Third Tibetan Plateau Atmospheric Scientific Experiment (TIPEX-III), the simulated microphysics and precipitation by the Weather Research and Forecasting model (WRF) with the Chinese Academy of Meteorological Sciences (CAMS) microphysics and other microphysical schemes are investigated through a typical plateau rainfall event on 22 July 2014. Results show that the WRF-CAMS simulation reasonably reproduces the spatial distribution of 24-h accumulated precipitation, but has limitations in simulating time evolutionmore » of precipitation rates. The model-calculated polarimetric radar variables have biases as well, suggesting bias in modeled hydrometeor types. The raindrop sizes in convective region are larger than those in stratiform region indicated by the small intercept of raindrop size distribution in the former. The sensitivity experiments show that precipitation processes are sensitive to the changes of warm rain processes in condensation and nucleated droplet size (but less sensitive to evaporation process). Increasing droplet condensation produces the best area-averaged rain rate during weak convection period compared with the observation, suggesting a considerable bias in thermodynamics in the baseline simulation. Increasing the initial cloud droplet size causes the rain rate reduced by half, an opposite effect to that of increasing droplet condensation.« less

The Cooperative VAS Program with the Marshall Space Flight Center

NASA Technical Reports Server (NTRS)

Diak, George R.; Menzel, W. Paul

1988-01-01

Work was divided between the analysis/forecast model development and evaluation of the impact of satellite data in mesoscale numerical weather prediction (NWP), development of the Multispectral Atmospheric Mapping Sensor (MAMS), and other related research. The Cooperative Institute for Meteorological Satellite Studies (CIMSS) Synoptic Scale Model (SSM) has progressed from a relatively basic analysis/forecast system to a package which includes such features as nonlinear vertical mode initialization, comprehensive Planetary Boundary Layer (PBL) physics, and the core of a fully four-dimensional data assimilation package. The MAMS effort has produced a calibrated visible and infrared sensor that produces imager at high spatial resolution. The MAMS was developed in order to study small scale atmospheric moisture variability, to monitor and classify clouds, and to investigate the role of surface characteristics in the production of clouds, precipitation, and severe storms.

Initial performance of the radio occultation experiment in the Venus orbiter mission Akatsuki

NASA Astrophysics Data System (ADS)

Imamura, Takeshi; Ando, Hiroki; Tellmann, Silvia; Pätzold, Martin; Häusler, Bernd; Yamazaki, Atsushi; Sato, Takao M.; Noguchi, Katsuyuki; Futaana, Yoshifumi; Oschlisniok, Janusz; Limaye, Sanjay; Choudhary, R. K.; Murata, Yasuhiro; Takeuchi, Hiroshi; Hirose, Chikako; Ichikawa, Tsutomu; Toda, Tomoaki; Tomiki, Atsushi; Abe, Takumi; Yamamoto, Zen-ichi; Noda, Hirotomo; Iwata, Takahiro; Murakami, Shin-ya; Satoh, Takehiko; Fukuhara, Tetsuya; Ogohara, Kazunori; Sugiyama, Ko-ichiro; Kashimura, Hiroki; Ohtsuki, Shoko; Takagi, Seiko; Yamamoto, Yukio; Hirata, Naru; Hashimoto, George L.; Yamada, Manabu; Suzuki, Makoto; Ishii, Nobuaki; Hayashiyama, Tomoko; Lee, Yeon Joo; Nakamura, Masato

2017-10-01

After the arrival of Akatsuki spacecraft of Japan Aerospace Exploration Agency at Venus in December 2015, the radio occultation experiment, termed RS (Radio Science), obtained 19 vertical profiles of the Venusian atmosphere by April 2017. An onboard ultra-stable oscillator is used to generate stable X-band downlink signals needed for the experiment. The quantities to be retrieved are the atmospheric pressure, the temperature, the sulfuric acid vapor mixing ratio, and the electron density. Temperature profiles were successfully obtained down to 38 km altitude and show distinct atmospheric structures depending on the altitude. The overall structure is close to the previous observations, suggesting a remarkable stability of the thermal structure. Local time-dependent features are seen within and above the clouds, which is located around 48-70 km altitude. The H2SO4 vapor density roughly follows the saturation curve at cloud heights, suggesting equilibrium with cloud particles. The ionospheric electron density profiles are also successfully retrieved, showing distinct local time dependence. Akatsuki RS mainly probes the low and middle latitude regions thanks to the near-equatorial orbit in contrast to the previous radio occultation experiments using polar orbiters. Studies based on combined analyses of RS and optical imaging data are ongoing.[Figure not available: see fulltext.

Development of lidar sensor for cloud-based measurements during convective conditions

NASA Astrophysics Data System (ADS)

Vishnu, R.; Bhavani Kumar, Y.; Rao, T. Narayana; Nair, Anish Kumar M.; Jayaraman, A.

2016-05-01

Atmospheric convection is a natural phenomena associated with heat transport. Convection is strong during daylight periods and rigorous in summer months. Severe ground heating associated with strong winds experienced during these periods. Tropics are considered as the source regions for strong convection. Formation of thunder storm clouds is common during this period. Location of cloud base and its associated dynamics is important to understand the influence of convection on the atmosphere. Lidars are sensitive to Mie scattering and are the suitable instruments for locating clouds in the atmosphere than instruments utilizing the radio frequency spectrum. Thunder storm clouds are composed of hydrometers and strongly scatter the laser light. Recently, a lidar technique was developed at National Atmospheric Research Laboratory (NARL), a Department of Space (DOS) unit, located at Gadanki near Tirupati. The lidar technique employs slant path operation and provides high resolution measurements on cloud base location in real-time. The laser based remote sensing technique allows measurement of atmosphere for every second at 7.5 m range resolution. The high resolution data permits assessment of updrafts at the cloud base. The lidar also provides real-time convective boundary layer height using aerosols as the tracers of atmospheric dynamics. The developed lidar sensor is planned for up-gradation with scanning facility to understand the cloud dynamics in the spatial direction. In this presentation, we present the lidar sensor technology and utilization of its technology for high resolution cloud base measurements during convective conditions over lidar site, Gadanki.

Could cirrus clouds have warmed early Mars?

NASA Astrophysics Data System (ADS)

Ramirez, Ramses M.; Kasting, James F.

2017-01-01

The presence of the ancient valley networks on Mars indicates that the climate at 3.8 Ga was warm enough to allow substantial liquid water to flow on the martian surface for extended periods of time. However, the mechanism for producing this warming continues to be debated. One hypothesis is that Mars could have been kept warm by global cirrus cloud decks in a CO2sbnd H2O atmosphere containing at least 0.25 bar of CO2 (Urata and Toon, 2013). Initial warming from some other process, e.g., impacts, would be required to make this model work. Those results were generated using the CAM 3-D global climate model. Here, we use a single-column radioactive-convective climate model to further investigate the cirrus cloud warming hypothesis. Our calculations indicate that cirrus cloud decks could have produced global mean surface temperatures above freezing, but only if cirrus cloud cover approaches ∼75 - 100% and if other cloud properties (e.g., height, optical depth, particle size) are chosen favorably. However, at more realistic cirrus cloud fractions, or if cloud parameters are not optimal, cirrus clouds do not provide the necessary warming, suggesting that other greenhouse mechanisms are needed.

A Review of Spatial and Seasonal Changes in Condensation Clouds Observed During Aerobraking by MGS TES

NASA Technical Reports Server (NTRS)

Pearl, J. C.; Smith, M. D.; Conrath, B. J.; Bandfield, J. L.; Christensen, P. R.

1999-01-01

Successful operation of the Mars Global Surveyor spacecraft beginning in September 1997, has permitted extensive infrared observations of condensation clouds during the martian southern summer and fall seasons (184 deg

In Situ Probe Science at Saturn

NASA Astrophysics Data System (ADS)

Atkinson, David H.; Lunine, Jonathan I.; Simon-Miller, Amy A.; Atreya, Sushil K.; Brinckerhoff, William B.; Colaprete, Anthony; Coustenis, Athena; Fletcher, Leigh N.; Guillot, Tristan; Lebreton, Jean-Pierre; Mahaffy, Paul; Mousis, Olivier; Orton, Glenn S.; Reh, Kim; Spilker, Linda J.; Spilker, Thomas R.; Webster, Chris R.

2014-05-01

A fundamental goal of solar system exploration is to understand the origin of the solar system, the initial stages, conditions, and processes by which the solar system formed, how the formation process was initiated, and the nature of the interstellar seed material from which the solar system was born. Key to understanding solar system formation and subsequent dynamical and chemical evolution is the origin and evolution of the giant planets and their atmospheres. Several theories have been put forward to explain the process of solar system formation, and the origin and evolution of the giant planets and their atmospheres. Each theory offers quantifiable predictions of the abundances of noble gases He, Ne, Ar, Kr, and Xe, and abundances of key isotopic ratios 4He/3He, D/H, 15N/14N, 18O/16O, and 13C/12C. Detection of certain disequilibrium species, diagnostic of deeper internal processes and dynamics of the atmosphere, would also help discriminate between competing theories. Many of the key atmospheric constituents needed to discriminate between alternative theories of giant planet formation and chemical evolution are either spectrally inactive or primarily located in the deeper atmosphere inaccessible to remote sensing from Earth, flyby, or orbiting spacecraft. Abundance measurements of these key constituents, including the two major molecular carriers of carbon, methane and carbon monoxide (neither of which condense in Saturn's atmosphere), sulfur which is expected to be well-mixed below the 4 to 5-bar ammonium hydrosulfide (NH4SH) cloud, and gradients of nitrogen below the NH4SH cloud and oxygen in the upper layers of the H2O and H2O-NH4 solution cloud, must be made in situ and can only be achieved by an entry probe descending through 10 bars. Measurements of the critical abundance profiles of these key constituents into the deeper well-mixed atmosphere must be complemented by measurements of the profiles of atmospheric structure and dynamics at high vertical resolution that also require in situ exploration. The atmospheres of the giant planets can also serve as laboratories to better understand the atmospheric chemistries, dynamics, processes, and climates on all planets in the solar system including Earth, and offer a context and provide a ground truth for exoplanets and exoplanetary systems. Additionally, Giant planets have long been thought to play a critical role in the development of potentially habitable planetary systems. In the context of giant planet science provided by the Galileo, Juno, and Cassini missions to Jupiter and Saturn, a small, relatively shallow Saturn probe capable of measuring abundances and isotopic ratios of key atmospheric constituents, and atmospheric structure including pressures, temperatures, dynamics, and cloud locations and properties not accessible by remote sensing can serve to test competing theories of solar system and giant planet origin, chemical, and dynamical evolution. Acknowledgements This research was carried out in part at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA. Copyright 2013 California Institute of Technology. U.S. Government sponsorship acknowledged. O. Mousis acknowledges support from CNES.

A unified theory for ice vapor growth suitable for cloud models: Testing and implications for cold cloud evolution

NASA Astrophysics Data System (ADS)

Zhang, Chengzhu

A new microphysical model for the vapor growth and aspect ratio evolution of atmospheric ice crystals is presented. The method is based on the adaptive habit model of Chen and Lamb (1994), but is modified to include surface kinetic processes for crystal growth. Inclusion of surface kinetic effects is accomplished with a new theory that accounts for axis dependent growth. Deposition coefficients (growth efficiencies) are predicted for two axis directions based on laboratory-determined parameters for growth initiation (critical supersaturations) on each face. In essence, the new theory extends the adaptive habit approach of Chen and Lamb (1994) to ice saturation states below that of liquid saturation, where Chen and Lamb (1994) is likely most valid. The new model is used to simulate changes in crystal primary habit as a function of temperature and ice supersaturation. Predictions are compared with a detailed hexagonal growth model both in a single particle framework and in a Lagrangian parcel model to indicate the accuracy of the new method. Moreover, predictions of the ratio of the axis deposition coefficients match laboratory-generated data. A parameterization for predicting deposition coefficients is developed for the bulk microphysics frame work in Regional Atmospheric Modeling System (RAMS). Initial eddy-resolving model simulation is conducted to study the effect of surface kinetics on microphysical and dynamical processes in cold cloud development.

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;

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.

International Workshop on Comparing Ice Nucleation Measuring Systems 2014

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cziczo, Daniel

The relationship of ambient aerosol particles to the formation of ice-containing clouds is one of the largest uncertainties in understanding the Earth’s climate. The uncertainty is due to several poorly understood processes and measurements including, but not limited to: (1) the microphysics of how particles nucleate ice, (2) the number of ice forming particles as a function of atmospheric properties such as temperature and relative humidity, (3) the atmospheric distribution of ice forming particles and (4) the role of anthropogenic activities in producing or changing the behavior of ice forming particles. The ways in which ice forming particles can impactmore » climate is also multi-faceted. More ice forming particles can lead to clouds with more ice crystals and different optical properties than clouds with less ice forming particles. More effective ice forming particles can lead to ice at higher temperature and/or lower saturation, resulting in clouds at lower altitude or latitude which also changes the Earth’s radiative balance. Ice nucleation also initiates most of the Earth’s precipitation, even in the mid- and low-latitudes, since cloud-top temperatures are often below freezing. The limited measurements and lack of understanding directly translates to restrictions in our ability to model atmospheric ice formation and project changes into the future. The importance of ice nucleation research is further exemplified by Figure 1 which shows the publications per decade and citations per year on the topic of ice nucleation [DeMott et al., 2011]. After a lull at the end of the last century, there has been a dramatic increase in both publications and citations related to ice nucleation; this directly corresponds to the importance of ice nucleation on the Earth’s climate and the uncertainty in this area noted by the Solomon [2007].« less

Data Archive and Portal Thrust Area Strategy Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sivaraman, Chitra; Stephan, Eric G.; Macduff, Matt C.

2014-09-01

This report describes the Data Archive and Portal (DAP), a key capability of the U.S. Department of Energy's Atmosphere to Electron (A2e) initiative. The DAP Thrust Area Planning Group was organized to develop a plan for deploying this capability. Primarily, the report focuses on a distributed system--a DOE Wind Cloud--that functions as a repository for all A2e data. The Wind Cloud will be accessible via an open, easy-to-navigate user interface that facilitates community data access, interaction, and collaboration. DAP management will work with the community, industry, and international standards bodies to develop standards for wind data and to capture importantmore » characteristics of all data in the Wind Cloud.« less

Do airborne microbes matter for atmospheric chemistry and cloud formation?

PubMed

Konstantinidis, Konstantinos T

2014-06-01

The role of airborne microbial cells in the chemistry of the atmosphere and cloud formation remains essentially speculative. Recent studies have indicated that microbes might be more important than previously anticipated for atmospheric processes. However, more work and direct communication between microbiologists and atmospheric scientists and modellers are necessary to better understand and model bioaerosol-cloud-precipitation-climate interactions. © 2014 Society for Applied Microbiology and John Wiley & Sons Ltd.

Chemical Impact of Solar Energetic Particle Event From The Young Sun: Implications for the Origin of Prebiotic Chemistry and the Fain Young Sun Paradox

NASA Astrophysics Data System (ADS)

Airapetian, V.; Gronoff, G.; Hébrard, E.; Danchi, W.

2015-12-01

Understanding how the simple molecules present on the early Earth and possibly Mars may have set a path for complex biological molecules, the building blocks of life, represents one of greatest unsolved questions. Here we present a new model of the rise of the abiotic nitrogen fixation and associated pre-biotic chemistry in the early Earth and Mars atmosphere mediated by solar eruptive events. Our physical models of interaction of magnetic clouds ejected from the young Sun with magnetospheres of the early Earth show significant perturbations of geomagnetic fields that produce extended polar caps. These polar caps provide pathways for energetic particles associated with magnetic clouds to penetrate into the nitrogen-rich weakly reducing atmosphere and initiate the reactive chemistry by breaking molecular nitrogen, carbon dioxide, methane and producing hydrogen cyanide, the essential compound for life. The model also shows that contrary to the current models of warming of early Earth and Mars, major atmospheric constituents, CO2 and CH4 will be destroyed due to collisional dissociation with energetic particles. Instead, efficient formation of the potent greenhouse gas, nitrous oxide, as a by-product of these processes is expected. This mechanism can consistently explain the Faint Young Sun's paradox for the early atmospheres of Earth and Mars. Our new model provides insight into how life may have initiated on Earth and Mars and how to search for the spectral signatures on planets "pregnant" with the potential for life.

A Southern California Perspective of the April, 1998 Trans-Pacific Asian Dust Event

NASA Technical Reports Server (NTRS)

Tratt, David M.; Frouin, Robert J.; Westphal, Douglas L.

1999-01-01

The Jet Propulsion Laboratory (JPL) coherent CO2 backscatter lidar has been in almost continuous operation since 1984 and has now accumulated a significant time-series database tracking the long-term and seasonal variability of backscatter from the atmospheric column above the Pasadena, Calif. locale. A particularly noteworthy episode observed by the lidar in 1998 was a particularly extreme instance of incursion by Asian-sourced dust during the closing days of April. Such events are not uncommon during the northern spring, when strong cold fronts and convection over the Asian interior deserts loft crustal material into the mid-troposphere whence it can be transported across the Pacific Ocean, occasionally reaching the continental US. However, the abnormal strength of the initiating storm in this case generated an atypically dense cloud of material which resulted in dramatically reduced visibility along the length of the Western Seaboard. These dust events are now recognized as a potentially significant, non-negligible radiative forcing influence. The progress of the April 1998 dust cloud eastward across the Pacific Ocean was initially observed in satellite imagery and transmitted to the broader atmospheric research community via electronic communications. The use of Internet technology in this way was effective in facilitating a rapid response correlative measurement exercise by numerous atmospheric observation stations throughout the western US and its success has resulted in the subsequent establishment of an ad hoc communications environment, data exchange medium, and mechanism for providing early-warning alert of other significant atmospheric phenomena in the future.

Climatology analysis of cirrus cloud in ARM site: South Great Plain

NASA Astrophysics Data System (ADS)

Olayinka, K.

2017-12-01

Cirrus cloud play an important role in the atmospheric energy balance and hence in the earth's climate system. The properties of optically thin clouds can be determined from measurements of transmission of the direct solar beam. The accuracy of cloud optical properties determined in this way is compromised by contamination of the direct transmission by light that is scattered into the sensors field of view. With the forward scattering correction method developed by Min et al., (2004), the accuracy of thin cloud retrievals from MFRSR has been improved. Our result shows over 30% of cirrus cloud present in the atmosphere are within optical depth between (1-2). In this study, we do statistics studies on cirrus clouds properties based on multi-years cirrus cloud measurements from MFRSR at ARM site from the South Great Plain (SGP) site due to its relatively easy accessibility, wide variability of climate cloud types and surface flux properties, large seasonal variation in temperature and specific humidity. Through the statistic studies, temporal and spatial variations of cirrus clouds are investigated. Since the presence of cirrus cloud increases the effect of greenhouse gases, we will retrieve the aerosol optical depth in all the cirrus cloud regions using a radiative transfer model for atmospheric correction. Calculate thin clouds optical depth (COD), and aerosol optical depth (AOD) using a radiative transfer model algorithm, e.g.: MODTRAN (MODerate resolution atmospheric TRANsmission)

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

NASA Technical Reports Server (NTRS)

Titlow, James; Baum, Bryan A.

1993-01-01

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

Multi-year global climatic effects of atmospheric dust from large bolide impacts

NASA Technical Reports Server (NTRS)

Thompson, Starley L.

1988-01-01

The global climatic effects of dust generated by the impact of a 10 km-diameter bolide was simulated using a one-dimensional (vertical only) globally-averaged climate model by Pollack et al. The goal of the simulation is to examine the regional climate effects, including the possibility of coastal refugia, generated by a global dust cloud in a model having realistic geographic resolution. The climate model assumes the instantaneous appearance of a global stratospheric dust cloud with initial optical depth of 10,000. The time history of optical depth decreases according to the detailed calculations of Pollack et al., reaching an optical depth of unity at day 160, and subsequently decreasing with an e-folding time of 1 year. The simulation is carried out for three years in order to examine the atmospheric effects and recovery over several seasons. The simulation does not include any effects of NOx, CO2, or wildfire smoke injections that may accompany the creation of the dust cloud. The global distribution of surface temperature changes, freezing events, precipitation and soil moisture effects and sea ice increases will be discussed.

CALIPSO Satellite Lidar Identification Of Elevated Dust Over Australia Compared With Air Quality Model PM60 Forecasts

NASA Technical Reports Server (NTRS)

Young, Stuart A.; Vaughan, Mark; Omar, Ali; Liu, Zhaoyan; Lee, Sunhee; Hu, Youngxiang; Cope, Martin

2008-01-01

Global measurements of the vertical distribution of clouds and aerosols have been recorded by the lidar on board the CALIPSO (Cloud Aerosol Lidar Infrared Pathfinder Satellite Observations) satellite since June 2006. Such extensive, height-resolved measurements provide a rare and valuable opportunity for developing, testing and validating various atmospheric models, including global climate, numerical weather prediction, chemical transport and air quality models. Here we report on the initial results of an investigation into the performance of the Australian Air Quality Forecast System (AAQFS) model in forecasting the distribution of elevated dust over the Australian region. The model forecasts of PM60 dust distribution are compared with the CALIPSO lidar Vertical Feature Mask (VFM) data product. The VFM classifies contiguous atmospheric regions of enhanced backscatter as either cloud or aerosols. Aerosols are further classified into six subtypes. By comparing forecast PM60 concentration profiles to the spatial distribution of dust reported in the CALIPSO VFM, we can assess the model s ability to predict the occurrence and the vertical and horizontal extents of dust events within the study area.

Statistical thermodynamics and the size distributions of tropical convective clouds.

NASA Astrophysics Data System (ADS)

Garrett, T. J.; Glenn, I. B.; Krueger, S. K.; Ferlay, N.

2017-12-01

Parameterizations for sub-grid cloud dynamics are commonly developed by using fine scale modeling or measurements to explicitly resolve the mechanistic details of clouds to the best extent possible, and then to formulating these behaviors cloud state for use within a coarser grid. A second is to invoke physical intuition and some very general theoretical principles from equilibrium statistical thermodynamics. This second approach is quite widely used elsewhere in the atmospheric sciences: for example to explain the heat capacity of air, blackbody radiation, or even the density profile or air in the atmosphere. Here we describe how entrainment and detrainment across cloud perimeters is limited by the amount of available air and the range of moist static energy in the atmosphere, and that constrains cloud perimeter distributions to a power law with a -1 exponent along isentropes and to a Boltzmann distribution across isentropes. Further, the total cloud perimeter density in a cloud field is directly tied to the buoyancy frequency of the column. These simple results are shown to be reproduced within a complex dynamic simulation of a tropical convective cloud field and in passive satellite observations of cloud 3D structures. The implication is that equilibrium tropical cloud structures can be inferred from the bulk thermodynamic structure of the atmosphere without having to analyze computationally expensive dynamic simulations.

a Numerical Study of Close Approaches for a Cloud of Debris Considering Atmospheric Drag and Lift

NASA Astrophysics Data System (ADS)

Gomes, Vivian; Golebiewska, Justyna; Prado, Antonio

The present paper study close approaches between a group of debris and a planet. The dynamical model considers the atmosphere of the planet, both in terms of drag as well as lift. This cloud is created during the passage of the spacecraft by the atmosphere of the planet, which is the responsible by the explosion of the spacecraft. The dynamical system is compos by the planet, the Sun, and the spacecraft, which explodes and becomes a cloud of debris. The planet and the Sun are in circular planar orbits. The equations of motion are the ones of the circular planar restricted three-body problem with the addition of the forces given by the atmospheric: drag and lift. The planet Jupiter is used for the numerical simulations. The initial conditions of the spacecraft and the debris are specified at the periapsis, which is the point where the explosion occurs. The equations of motion are numerically integrated forward in time for each particle, until a point where the particle is at a distance that can be considered far enough from the planet and it is possible to disregard the effects of the planet and consider the Sun-particle as a two-body system. Then we compute the velocity, energy and angular momentum after the passage by the planet, for each particle, based in the two-body celestial mechanics. From those results, the eccentricity and the semi-major axis of each particle can be obtained. Then, the orbit of the spacecraft is integrated backwards in time, as a single body. The difference from the usual close approaches technique is the presence of the atmosphere of the planet, which generates a drag and a lift forces in the spacecraft, which causes the explosion and modifies the trajectories of the debris generated by the explosion. The primary objective of the present paper is to map the modifications of the orbits of the debris that compose the cloud due to the close approach with the planet. Emphasis is given to map the orbital parameters of the debris after the close approach with the planet. Then, the effects are compared with the same maneuvers performed without the inclusion of the atmosphere. This type of research is useful, because it helps to obtain the size and density of the cloud of debris after the passage, as a function of time. That information has impact on the evaluations of the risks that spacecrafts suffer when passing by shorter distances from this cloud.

The atmospheres of Saturn and Titan in the near-infrared: First results of Cassini/Vims

USGS Publications Warehouse

Baines, K.H.; Momary, T.W.; Buratti, B.J.; Matson, D.L.; Nelson, R.M.; Drossart, P.; Sicardy, B.; Formisano, V.; Bellucci, G.; Coradini, A.; Griffith, C.; Brown, R.H.; Bibring, J.-P.; Langevin, Y.; Capaccioni, F.; Cerroni, P.; Clark, R.N.; Combes, M.; Cruikshank, D.P.; Jaumann, R.; McCordt, T.B.; Mennella, V.; Nicholson, P.D.; Sotin, Christophe

2006-01-01

The wide spectral coverage and extensive spatial, temporal, and phase-angle mapping capabilities of the Visual Infrared Mapping Spectrometer (VIMS) onboard the Cassini-Huygens Orbiter are producing fundamental new insights into the nature of the atmospheres of Saturn and Titan. For both bodies, VIMS maps over time and solar phase angles provide information for a multitude of atmospheric constituents and aerosol layers, providing new insights into atmospheric structure and dynamical and chemical processes. For Saturn, salient early results include evidence for phosphine depletion in relatively dark and less cloudy belts at temperate and mid-latitudes compared to the relatively bright and cloudier Equatorial Region, consistent with traditional theories of belts being regions of relative downwelling. Additional Saturn results include (1) the mapping of enhanced trace gas absorptions at the south pole, and (2) the first high phase-angle, high-spatial-resolution imagery of CH4 fluorescence. An additional fundamental new result is the first nighttime near-infrared mapping of Saturn, clearly showing discrete meteorological features relatively deep in the atmosphere beneath the planet's sunlit haze and cloud layers, thus revealing a new dynamical regime at depth where vertical dynamics is relatively more important than zonal dynamics in determining cloud morphology. Zonal wind measurements at deeper levels than previously available are achieved by tracking these features over multiple days, thereby providing measurements of zonal wind shears within Saturn's troposphere when compared to cloudtop movements measured in reflected sunlight. For Titan, initial results include (1) the first detection and mapping of thermal emission spectra of CO, CO2, and CH3D on Titan's nightside limb, (2) the mapping of CH4 fluorescence over the dayside bright limb, extending to ??? 750 km altitude, (3) wind measurements of ???0.5 ms-1, favoring prograde, from the movement of a persistent (multiple months) south polar cloud near 88??S latitude, and (4) the imaging of two transient mid-southern-latitude cloud features. ?? Springer Science+Business Media, Inc. 2006.

CHEMISTRY OF SILICATE ATMOSPHERES OF EVAPORATING SUPER-EARTHS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schaefer, Laura; Fegley, Bruce, E-mail: laura_s@levee.wustl.ed, E-mail: bfegley@levee.wustl.ed

2009-10-01

We model the formation of silicate atmospheres on hot volatile-free super-Earths. Our calculations assume that all volatile elements such as H, C, N, S, and Cl have been lost from the planet. We find that the atmospheres are composed primarily of Na, O{sub 2}, O, and SiO gas, in order of decreasing abundance. The atmospheric composition may be altered by fractional vaporization, cloud condensation, photoionization, and reaction with any residual volatile elements remaining in the atmosphere. Cloud condensation reduces the abundance of all elements in the atmosphere except Na and K. We speculate that large Na and K clouds suchmore » as those observed around Mercury and Io may surround hot super-Earths. These clouds would occult much larger fractions of the parent star than a closely bound atmosphere, and may be observable through currently available methods.« less

Evaluation of a Mesoscale Atmospheric Dispersion Modeling System with Observations from the 1980 Great Plains Mesoscale Tracer Field Experiment. Part I: Datasets and Meteorological Simulations.

NASA Astrophysics Data System (ADS)

Moran, Michael D.; Pielke, Roger A.

1996-03-01

The Colorado State University mesoscale atmospheric dispersion (MAD) numerical modeling system, which consists of a prognostic mesoscale meteorological model coupled to a mesoscale Lagrangian particle dispersion model, has been used to simulate the transport and diffusion of a perfluorocarbon tracer-gas cloud for one afternoon surface release during the July 1980 Great Plains mesoscale tracer field experiment. Ground-level concentration (GLC) measurements taken along arcs of samplers 100 and 600 km downwind of the release site at Norman, Oklahoma, up to three days after the tracer release were available for comparison. Quantitative measures of a number of significant dispersion characteristics obtained from analysis of the observed tracer cloud's moving GLC `footprint' have been used to evaluate the modeling system's skill in simulating this MAD case.MAD is more dependent upon the spatial and temporal structure of the transport wind field than is short-range atmospheric dispersion. For the Great Plains mesoscale tracer experiment, the observations suggest that the Great Plains nocturnal low-level jet played an important role in transporting and deforming the tracer cloud. A suite of ten two- and three-dimensional numerical meteorological experiments was devised to investigate the relative contributions of topography, other surface inhomogeneities, atmospheric baroclinicity, synoptic-scale flow evolution, and meteorological model initialization time to the structure and evolution of the low-level mesoscale flow field and thus to MAD. Results from the ten mesoscale meteorological simulations are compared in this part of the paper. The predicted wind fields display significant differences, which give rise in turn to significant differences in predicted low-level transport. The presence of an oscillatory ageostrophic component in the observed synoptic low-level winds for this case is shown to complicate initialization of the meteorological model considerably and is the likely cause of directional errors in the predicted mean tracer transport. A companion paper describes the results from the associated dispersion simulations.

Assessing the Regional/Diurnal Bias between Satellite Retrievals and GEOS-5/MERRA Model Estimates of Land Surface Temperature

NASA Astrophysics Data System (ADS)

Scarino, B. R.; Smith, W. L., Jr.; Minnis, P.; Bedka, K. M.

2017-12-01

Atmospheric models rely on high-accuracy, high-resolution initial radiometric and surface conditions for better short-term meteorological forecasts, as well as improved evaluation of global climate models. Continuous remote sensing of the Earth's energy budget, as conducted by the Clouds and Earth's Radiant Energy System (CERES) project, allows for near-realtime evaluation of cloud and surface radiation properties. It is unfortunately common for there to be bias between atmospheric/surface radiation models and Earth-observations. For example, satellite-observed surface skin temperature (Ts), an important parameter for characterizing the energy exchange at the ground/water-atmosphere interface, can be biased due to atmospheric adjustment assumptions and anisotropy effects. Similarly, models are potentially biased by errors in initial conditions and regional forcing assumptions, which can be mitigated through assimilation with true measurements. As such, when frequent, broad-coverage, and accurate retrievals of satellite Ts are available, important insights into model estimates of Ts can be gained. The Satellite ClOud and Radiation Property retrieval System (SatCORPS) employs a single-channel thermal-infrared method to produce anisotropy-corrected Ts over clear-sky land and ocean surfaces from data taken by geostationary Earth orbit (GEO) satellite imagers. Regional and diurnal changes in model land surface temperature (LST) performance can be assessed owing to the somewhat continuous measurements of the LST offered by GEO satellites - measurements which are accurate to within 0.2 K. A seasonal, hourly comparison of satellite-observed LST with the NASA Goddard Earth Observing System Version 5 (GEOS-5) and the Modern-Era Retrospective Analysis for Research and Applications (MERRA) LST estimates is conducted to reveal regional and diurnal biases. This assessment is an important first step for evaluating the effectiveness of Ts assimilation, as well for determining the impact anisotropy correction has on observation - model bias, and is of critical importance for CERES.

Warming ancient Mars with water clouds

NASA Astrophysics Data System (ADS)

Hartwick, V.; Toon, B.

2017-12-01

High clouds in the present day Mars atmosphere nucleate on interplanetary dust particles (IDPs) that burn up on entry into the Mars atmosphere. Clouds form when superstaturated water vapor condenses on suspended aerosols. Radiatively active water ice clouds may play a crucial role in warming the early Mars climate. Urata and Toon (2011) simulate a stable warm paleo-climate for Mars if clouds 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 middle and high atmosphere was likely heightened . Both factors should contribute to enhanced nucleation and growth of water ice cloud particles at high altitudes. Here, we use the MarsCAM-CARMA general circulation model (GCM) to examine the radiative impact of high altitude water ice clouds on the early Mars climate and as a possible solution to the faint young sun problem for Mars.

Ice nucleation by particles immersed in supercooled cloud droplets.

PubMed

Murray, B J; O'Sullivan, D; Atkinson, J D; Webb, M E

2012-10-07

The formation of ice particles in the Earth's atmosphere strongly affects the properties of clouds and their impact on climate. Despite the importance of ice formation in determining the properties of clouds, the Intergovernmental Panel on Climate Change (IPCC, 2007) was unable to assess the impact of atmospheric ice formation in their most recent report because our basic knowledge is insufficient. Part of the problem is the paucity of quantitative information on the ability of various atmospheric aerosol species to initiate ice formation. Here we review and assess the existing quantitative knowledge of ice nucleation by particles immersed within supercooled water droplets. We introduce aerosol species which have been identified in the past as potentially important ice nuclei and address their ice-nucleating ability when immersed in a supercooled droplet. We focus on mineral dusts, biological species (pollen, bacteria, fungal spores and plankton), carbonaceous combustion products and volcanic ash. In order to make a quantitative comparison we first introduce several ways of describing ice nucleation and then summarise the existing information according to the time-independent (singular) approximation. Using this approximation in combination with typical atmospheric loadings, we estimate the importance of ice nucleation by different aerosol types. According to these estimates we find that ice nucleation below about -15 °C is dominated by soot and mineral dusts. Above this temperature the only materials known to nucleate ice are biological, with quantitative data for other materials absent from the literature. We conclude with a summary of the challenges our community faces.

Atmospheric Profiles, Clouds, and the Evolution of Sea Ice Cover in the Beaufort and Chukchi Seas Atmospheric Observations and Modeling as Part of the Seasonal Ice Zone Reconnaissance Surveys

DTIC Science & Technology

2013-09-30

Cover in the Beaufort and Chukchi Seas Atmospheric Observations and Modeling as Part of the Seasonal Ice Zone Reconnaissance Surveys Axel...how changes in sea ice and sea surface conditions in the SIZ affect changes in cloud properties and cover . • Determine the role additional atmospheric...REPORT TYPE 3. DATES COVERED 00-00-2013 to 00-00-2013 4. TITLE AND SUBTITLE Atmospheric Profiles, Clouds, and the Evolution of Sea Ice Cover in the

Sensitivity of a mesoscale model to initial specification of relative humidity, liquid water and vertical motion

NASA Technical Reports Server (NTRS)

Kalb, M. W.; Perkey, D. J.

1985-01-01

The influence of synoptic scale initial conditions on the accuracy of mesoscale precipitation modeling is investigated. Attention is focused on the relative importance of the water vapor, cloud water, rain water, and vertical motion, with the analysis carried out using the Limited Area Mesoscale Prediction System (LAMPS). The fully moist primitive equation model has 15 levels and a terrain-following sigma coordinate system. A K-theory approach was implemented to model the planetary boundary layer. A total of 15 sensitivity simulations were run to investigate the effects of the synoptic initial conditions of the four atmospheric variables. The absence of synoptic cloud and rain water amounts in the initialization caused a 2 hr delay in the onset of precipitation. The delay was increased if synoptic-scale vertical motion was used instead of mesoscale values. Both the delays and a choice of a smoothed moisture field resulted in underestimations of the total rainfall.

Adventure Learning @ Greenland

NASA Astrophysics Data System (ADS)

Miller, B. G.; Cox, C. J.; Hougham, J.; Walden, V. P.; Eitel, K.; Albano, A.

2013-12-01

Teaching the general public and K-12 communities about scientific research has taken on greater importance as climate change increasingly impacts the world we live in. Science researchers and the educational community have a widening responsibility to produce and deliver curriculum and content that is timely, scientifically sound and engaging. To address this challenge, in the summer of 2012 the Adventure Learning @ Greenland (AL@GL) project, a United States' National Science Foundation (NSF) funded initiative, used hands-on and web-based climate science experiences for high school students to promote climate and science literacy. This presentation will report on an innovative approach to education and outreach for environmental science research known as Adventure Learning (AL). The purpose of AL@GL was to engage high school students in the US, and in Greenland, in atmospheric research that is being conducted in the Arctic to enhance climate and science literacy. Climate and science literacy was explored via three fundamental concepts: radiation, the greenhouse effect, and climate vs. weather. Over the course of the project, students in each location engaged in activities and conducted experiments through the use of scientific instrumentation. Students were taught science research principles associated with an atmospheric observatory at Summit Station, Greenland with the objective of connecting climate science in the Arctic to student's local environments. Summit Station is located on the Greenland Ice Sheet [72°N, 38°W, 3200 m] and was the primary location of interest. Approximately 35 students at multiple locations in Idaho, USA, and Greenland participated in the hybrid learning environments as part of this project. The AL@GL project engaged students in an inquiry-based curriculum with content that highlighted a cutting-edge geophysical research initiative at Summit: the Integrated Characterization of Energy, Clouds, Atmospheric state, and Precipitation at Summit (ICECAPS) project (Shupe et al. 2012; http://www.esrl.noaa.gov/psd/arctic/observatories/summit/). ICECAPS is an atmospheric observatory focused on obtaining high temporal resolution measurements of clouds from ground-based remote sensors including radar, lidar, infrared spectra and others. ICECAPS also launches radiosondes twice daily. This large suite of complementary observations are providing an important baseline understanding of cloud and atmospheric conditions over the central Greenland ice sheet and are supporting Arctic climate research on cloud processes and climate model validation. ICECAPS measures parameters that are associated with those identified in student misconceptions, for example, different types of atmospheric radiation, the effect of greenhouse gases, and climate versus weather (see also Haller et al., 2011). Thus, ICECAPS research and the AL@GL project combined to create a learning environment and educational activities that sought to increase climate literacy in high school students as well as communicate important atmospheric research to a broader audience.

3.6 cm signal attenuation in Venus' lower and middle atmosphere observed by the Radio Science experiment VeRa onboard Venus Express

NASA Astrophysics Data System (ADS)

Oschlisniok, J.; Tellmann, S.; Pätzold, M.; Häusler, B.; Andert, T.; Bird, M.; Remus, S.

2012-09-01

The planet Venus is shrouded within a roughly 20 km thick cloud layer, which extends from the lower to the middle atmosphere (ca. 50 - 70 km). While the clouds are mostly composed of sulfuric acid droplets, a haze layer of sulfuric acid vapor exists below the clouds. Within the cloud and the sub - cloud 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 cloud region with respect to atmospheric waves. The absorption of the signal is used to determine the abundance of H2SO4 near the cloud base. This way a detailed study of the H2SO4 abundance within the cloud and sub - cloud region is possible. Results from the intensity scintillations within the cloud 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.

Cloud diagnosis impact on deposition modelling applied to the Fukushima accident

NASA Astrophysics Data System (ADS)

Quérel, Arnaud; Quélo, Denis; Roustan, Yelva; Mathieu, Anne

2017-04-01

The accident at the Fukushima Daiichi Nuclear Power Plant in Japan in March 2011 resulted in the release of several hundred PBq of activity into the environment. Most of the radioactivity was released in a time period of about 40 days. Radioactivity was dispersed in the atmosphere and the ocean and subsequently traces of radionuclides were detected all over Japan. At the Fukushima airport for instance, a deposit as large as 36 kBq/m2 of Cs-137 was measured resulting of an atmospheric deposition of the plume. Both dry and wet deposition were probably involved since a raining event occurred on the 15th of March when the plume was passing nearby. The accident scenario have given rise to a number of scientific investigations. Atmospheric deposition, for example, was studied by utilizing atmospheric transport models. In atmospheric transport models, some parameters, such as cloud diagnosis, are derived from meteorological data. This cloud diagnosis is a key issue for wet deposition modelling since it allows to distinguish between two processes: in-cloud scavenging which corresponds to the collection of radioactive particles into the cloud and below-cloud scavenging consequent to the removal of radioactive material due to the falling drops. Several parametrizations of cloud diagnosis exist in the literature, using different input data: relative humidity, liquid water content, also. All these diagnosis return a large range of cloud base heights and cloud top heights. In this study, computed cloud diagnostics are compared to the observations at the Fukushima airport. Atmospheric dispersion simulations at Japan scale are then performed utilizing the most reliable ones. Impact on results are discussed.

Atmospheric microphysical experiments on an orbital platform

NASA Technical Reports Server (NTRS)

Eaton, L. R.

1974-01-01

The Zero-Gravity Atmospheric Cloud Physics Laboratory is a Shuttle/Spacelab payload which will be capable of performing a large range of microphysics experiments. This facility will complement terrestrial cloud physics research by allowing many experiments to be performed which cannot be accomplished within the confines of a terrestrial laboratory. This paper reviews the general Cloud Physics Laboratory concept and the experiment scope. The experimental constraints are given along with details of the proposed equipment. Examples of appropriate experiments range from three-dimensional simulation of the earth and planetary atmosphere and of ocean circulation to cloud electrification processes and the effects of atmospheric pollution materials on microphysical processes.

Does a Relationship Between Arctic Low Clouds and Sea Ice Matter?

NASA Technical Reports Server (NTRS)

Taylor, Patrick C.

2016-01-01

Arctic low clouds strongly affect the Arctic surface energy budget. Through this impact Arctic low clouds influence important aspects of the Arctic climate system, namely surface and atmospheric temperature, sea ice extent and thickness, and atmospheric circulation. Arctic clouds are in turn influenced by these elements of the Arctic climate system, and these interactions create the potential for Arctic cloud-climate feedbacks. To further our understanding of potential Arctic cloudclimate feedbacks, the goal of this paper is to quantify the influence of atmospheric state on the surface cloud radiative effect (CRE) and its covariation with sea ice concentration (SIC). We build on previous research using instantaneous, active remote sensing satellite footprint data from the NASA A-Train. First, the results indicate significant differences in the surface CRE when stratified by atmospheric state. Second, there is a weak covariation between CRE and SIC for most atmospheric conditions. Third, the results show statistically significant differences in the average surface CRE under different SIC values in fall indicating a 3-5 W m(exp -2) larger LW CRE in 0% versus 100% SIC footprints. Because systematic changes on the order of 1 W m(exp -2) are sufficient to explain the observed long-term reductions in sea ice extent, our results indicate a potentially significant amplifying sea ice-cloud feedback, under certain meteorological conditions, that could delay the fall freeze-up and influence the variability in sea ice extent and volume. Lastly, a small change in the frequency of occurrence of atmosphere states may yield a larger Arctic cloud feedback than any cloud response to sea ice.

Evaluation of Arctic Clouds And Their Response to External Forcing in Climate Models

NASA Astrophysics Data System (ADS)

Wang, Y.; Jiang, J. H.; Ming, Y.; Su, H.; Yung, Y. L.

2017-12-01

A warming Arctic is undergoing significant environmental changes, mostly evidenced by the reduction in Arctic sea-ice extent (SIE). However, the role of Arctic clouds in determining the sea ice melting remains elusive, as different phases of clouds can induce either positive or negative radiative forcing in different seasons. The possible cloud feedbacks following the opened ocean surface are also debatable due to variations of polar boundary structure. Therefore, Arctic cloud simulation has long been considered as the largest source of uncertainty in the climate sensitivity assessment. Other local or remote atmospheric factors, such as poleward moisture and heat transport as well as atmospheric aerosols seeding liquid and ice clouds, further complicate our understanding of the Arctic cloud change. Our recent efforts focus on the post-CMIP5 and CMIP6 models, which improve atmospheric compositions, cloud macro- and microphysics, convection parameterizations, etc. In this study, we utilize long-term satellite measurements with high-resolution coverage and broad wavelength spectrum to evaluate the mean states and variations of mixed-phase clouds in the Arctic, along with the concurrent moisture and SIE measurements. The model sensitivity experiments to understand external perturbations on the atmosphere-cryosphere coupling in the Arctic will be presented.

Looking Down Through the Clouds – Optical Attenuation through Real-Time Clouds

NASA Astrophysics Data System (ADS)

Burley, J.; Lazarewicz, A.; Dean, D.; Heath, N.

Detecting and identifying nuclear explosions in the atmosphere and on the surface of the Earth is critical for the Air Force Technical Applications Center (AFTAC) treaty monitoring mission. Optical signals, from surface or atmospheric nuclear explosions detected by satellite sensors, are attenuated by the atmosphere and clouds. Clouds present a particularly complex challenge as they cover up to seventy percent of the earth's surface. Moreover, their highly variable and diverse nature requires physics-based modeling. Determining the attenuation for each optical ray-path is uniquely dependent on the source geolocation, the specific optical transmission characteristics along that ray path, and sensor detection capabilities. This research details a collaborative AFTAC and AFIT effort to fuse worldwide weather data, from a variety of sources, to provide near-real-time profiles of atmospheric and cloud conditions and the resulting radiative transfer analysis for virtually any wavelength(s) of interest from source to satellite. AFIT has developed a means to model global clouds using the U.S. Air Force’s World Wide Merged Cloud Analysis (WWMCA) cloud data in a new toolset that enables radiance calculations through clouds from UV to RF wavelengths.

The Impact of Aerosols on Cloud and Precipitation Processes: Cloud-Resolving Model Simulations

NASA Technical Reports Server (NTRS)

Tao, Wei-Kuo; Khain, A.; Simpson, S.; Johnson, D.; Li, X.; Remer, L.

2003-01-01

Cloud microphysics are inevitable affected by the smoke particle (CCN, cloud condensation nuclei) size distributions below the clouds. Therefore, size distribution parameterized as spectral bin microphysics are needed to explicitly study the effect of atmospheric aerosol concentration on cloud development, rainfall production, and rainfall rates convective clouds. Recently, two detailed spectral-bin microphysical schemes were implemented into the Goddard Cumulus Ensembel (GCE) model. The formulation for the explicit spectral-bim microphysical processes is based on solving stochastic kinetic equations for the size distribution functions of water droplets (i.e., cloud droplets and raindrops), and several types of ice particles [i.e., pristine ice crystals (columnar and plate-like), snow (dendrites and aggregates), groupel and frozen drops/hall] Each type is described by a special size distribution function containing many categories (i.e., 33 bins). Atmospheric aerosols are also described using number density size-distribution functions.A spectral-bin microphysical model is very expensive from a computational point of view and has only been implemented into the 2D version of the GCE at the present time. The model is tested by studying the evolution of deep cloud systems in the west Pacific warm pool region and in the mid-latitude using identical thermodynamic conditions but with different concentrations of CCN: a low "clean" concentration and a high "dirty" concentration. Besides the initial differences in aerosol concentration, preliminary results indicate that the low CCN concentration case produces rainfall at the surface sooner than the high CCN case but has less cloud water mass aloft. Because the spectral-bim model explicitly calculates and allows for the examination of both the mass and number concentration of cpecies in each size category, a detailed analysis of the instantaneous size spectrum can be obtained for the two cases. It is shown that since the low CCN case produces fever droplets, larger size develop due to greater condencational and collectional growth, leading to a broader size spectrum in comparison to the high CCN case.

The Impact of Aerosols on Cloud and Precipitation Processes: Cloud-Resolving Model Simulations

NASA Technical Reports Server (NTRS)

Tao, Wei-Kuo; Khain, A.; Simpson, S.; Johnson, D.; Li, X.; Remer, L.

2003-01-01

Cloud microphysics are inevitably affected by the smoke particle (CCN, cloud condensation nuclei) size distributions below the clouds. Therefore, size distributions parameterized as spectral bin microphysics are needed to explicitly study the effects of atmospheric aerosol concentration on cloud development, rainfall production, and rainfall rates for convective clouds. Recently, two detailed spectral-bin microphysical schemes were implemented into the Goddard Cumulus Ensemble (GCE) model. The formulation for the explicit spectral-bin microphysical processes is based on solving stochastic kinetic equations for the size distribution functions of water droplets (i.e., cloud droplets and raindrops), and several types of ice particles [i.e.,pristine ice crystals (columnar and plate-like), snow (dendrites and aggregates), graupel and frozen drops/hail]. Each type is described by a special size distribution function containing many categories (i.e. 33 bins). Atmospheric aerosols are also described using number density size-distribution functions.A spectral-bin microphysical model is very expensive from a from a computational point of view and has only been implemented into the 2D version of the GCE at the present time. The model is tested by studying the evolution of deep tropical clouds in the west Pacific warm pool region using identical thermodynamic conditions but with different concentrations of CCN: a low "clean" concentration and a high "dirty" concentration. Besides the initial differences in aerosol concentration, preliminary results indicate that the low CCN concentration case produces rainfall at the surface sooner than the high CCN case but has less cloud water mass aloft. Because the spectral-bin model explicitly calculates and allows for the examination of both the mass and number concentration of species in each size categor, a detailed analysis of the instantaneous size spectrum can be obtained for the two cases. It is shown that since the low CCN case produces fewer droplets, larger sized develop due to the greater condensational and collectional growth, leading to a broader size spectrum in comparison to the high CCN case.

Aerosol and Cloud Observations and Data Products by the GLAS Polar Orbiting Lidar Instrument

NASA Technical Reports Server (NTRS)

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

2005-01-01

The Geoscience Laser Altimeter System (GLAS) launched in 2003 is the first polar orbiting satellite lidar. The instrument was designed for high performance observations of the distribution and optical scattering cross sections of clouds and aerosol. The backscatter lidar operates at two wavelengths, 532 and 1064 nm. Both receiver channels meet and exceed their design goals, and beginning with a two month period through October and November 2003, an excellent global lidar data set now exists. The data products for atmospheric observations include the calibrated, attenuated backscatter cross section for cloud and aerosol; height detection for multiple cloud layers; planetary boundary layer height; cirrus and aerosol optical depth and the height distribution of aerosol and cloud scattering cross section profiles. The data sets are now in open release through the NASA data distribution system. The initial results on global statistics for cloud and aerosol distribution has been produced and in some cases compared to other satellite observations. The sensitivity of the cloud measurements is such that the 70% global cloud coverage result should be the most accurate to date. Results on the global distribution of aerosol are the first that produce the true height distribution for model inter-comparison.

Outer satellite atmospheres: Their nature and planetary interactions. [atmospheric models for Amalthea, Ganymede, Callisto, and Titan are presented

NASA Technical Reports Server (NTRS)

Smyth, W. H.

1978-01-01

Results show that Amalthea is likely to form a tightly-bound partial toroidal-shaped hydrogen cloud about its planet, while Ganymede, Callisto and Titan may have rather large, complete and nearly symmetric toroidal-shaped clouds. The toroidal cloud for Amalthea compares favorably with spacecraft data of Pioneer 10 for a satellite escape flux of order 10 to the 11th power atoms/sq cm/sec. Model results for Ganymede, Callisto and Titan suggest that these extended hydrogen atmospheres are likely to be detected by the Voyager spacecrafts and that Titan's cloud might also be detected by the Pioneer 11 spacecraft. Ions created because of atoms lost through ionization processes from these four extended hydrogen atmospheres and from the sodium cloud of Io are discussed.

Investigating expanded chemistry in CMAQ clouds

EPA Science Inventory

Clouds and fogs significantly impact the amount, composition, and spatial distribution of gas and particulate atmospheric species, not least of which through the chemistry that occurs in cloud droplets.ﾠ Atmospheric sulfate is an important component of fine aerosol mass an...

Yield and ion distribution for the barium cloud at 31,000 kilometers, September 21, 1971.

NASA Technical Reports Server (NTRS)

Manring, E. R.; Patty, R. R.

1973-01-01

The photon flux density associated with the 4554-A resonance radiation for Ba II was measured at Mount Hopkins, Arizona, and Cerro Morado, Chile, and was determined to be 36,000 photon/sq cm sec outside the atmosphere; this measurement was made when the cloud was optically thin at 120 sec after release. Using this and a photon scattering efficiency of 0.66 photon/ion sec we estimate a 1.7-kg yield of barium ions that are formed from the initially released atomic barium and are thus associated with the main core of the cloud. Photographic and photometric data are combined to obtain preliminary values for the brightness throughout the cloud for two photographs, and isobrightness plots are presented. These plots indicate that the cloud is quite narrow, that a considerable portion of the ionized barium is outside the main core after a few minutes, and that the striations contain only a small fraction of the total material.

Classification of Clouds and Deep Convection from GEOS-5 Using Satellite Observations

NASA Technical Reports Server (NTRS)

Putman, William; Suarez, Max

2010-01-01

With the increased resolution of global atmospheric models and the push toward global cloud resolving models, the resemblance of model output to satellite observations has become strikingly similar. As we progress with our adaptation of the Goddard Earth Observing System Model, Version 5 (GEOS-5) as a high resolution cloud system resolving model, evaluation of cloud properties and deep convection require in-depth analysis beyond a visual comparison. Outgoing long-wave radiation (OLR) provides a sufficient comparison with infrared (IR) satellite imagery to isolate areas of deep convection. We have adopted a binning technique to generate a series of histograms for OLR which classify the presence and fraction of clear sky versus deep convection in the tropics that can be compared with a similar analyses of IR imagery from composite Geostationary Operational Environmental Satellite (GOES) observations. We will present initial results that have been used to evaluate the amount of deep convective parameterization required within the model as we move toward cloud system resolving resolutions of 10- to 1-km globally.

Odd cloud in the Ross Sea, Antarctica

NASA Technical Reports Server (NTRS)

2002-01-01

On January 28, 2002, MODIS captured this image of an interesting cloud formation in the boundary waters between Antarctica's Ross Sea and the Southern Ocean. A dragon? A snake? A fish? No, but it is an interesting example of the atmospheric physics of convection. The 'eye' of this dragon-looking cloud is likely a small spot of convection, the process by which hot moist air rises up into the atmosphere, often producing big, fluffy clouds as moisture in the air condenses as rises into the colder parts of the atmosphere. A false color analysis that shows different kinds of clouds in different colors reveals that the eye is composed of ice crystals while the 'body' is a liquid water cloud. This suggests that the eye is higher up in the atmosphere than the body. The most likely explanation for the eye feature is that the warm, rising air mass had enough buoyancy to punch through the liquid water cloud. As a convective parcel of air rises into the atmosphere, it pushes the colder air that is higher up out of its way. That cold air spills down over the sides of the convective air mass, and in this case has cleared away part of the liquid cloud layer below in the process. This spilling over of cold air from higher up in the atmosphere is the reason why thunderstorms are often accompanied by a cool breeze. Credit: Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC

Clouds and the Earth's Radiant Energy System (CERES) algorithm theoretical basis document. volume 4; Determination of surface and atmosphere fluxes and temporally and spatially averaged products (subsystems 5-12); Determination of surface and atmosphere fluxes and temporally and spatially averaged products

NASA Technical Reports Server (NTRS)

Wielicki, Bruce A. (Principal Investigator); Barkstrom, Bruce R. (Principal Investigator); Baum, Bryan A.; Charlock, Thomas P.; Green, Richard N.; Lee, Robert B., III; Minnis, Patrick; Smith, G. Louis; Coakley, J. A.; Randall, David R.

1995-01-01

The theoretical bases for the Release 1 algorithms that will be used to process satellite data for investigation of the Clouds and the Earth's Radiant Energy System (CERES) are described. The architecture for software implementation of the methodologies is outlined. Volume 4 details the advanced CERES techniques for computing surface and atmospheric radiative fluxes (using the coincident CERES cloud property and top-of-the-atmosphere (TOA) flux products) and for averaging the cloud properties and TOA, atmospheric, and surface radiative fluxes over various temporal and spatial scales. CERES attempts to match the observed TOA fluxes with radiative transfer calculations that use as input the CERES cloud products and NOAA National Meteorological Center analyses of temperature and humidity. Slight adjustments in the cloud products are made to obtain agreement of the calculated and observed TOA fluxes. The computed products include shortwave and longwave fluxes from the surface to the TOA. The CERES instantaneous products are averaged on a 1.25-deg latitude-longitude grid, then interpolated to produce global, synoptic maps to TOA fluxes and cloud properties by using 3-hourly, normalized radiances from geostationary meteorological satellites. Surface and atmospheric fluxes are computed by using these interpolated quantities. Clear-sky and total fluxes and cloud properties are then averaged over various scales.

Non-hydrostatic general circulation model of the Venus atmosphere

NASA Astrophysics Data System (ADS)

Rodin, Alexander V.; Mingalev, Igor; Orlov, Konstantin; Ignatiev, Nikolay

We present the first non-hydrostatic global circulation model of the Venus atmosphere based on the complete set of gas dynamics equations. The model employs a spatially uniform triangular mesh that allows to avoid artificial damping of the dynamical processes in the polar regions, with altitude as a vertical coordinate. Energy conversion from the solar flux into atmospheric motion is described via explicitly specified heating and cooling rates or, alternatively, with help of the radiation block based on comprehensive treatment of the Venus atmosphere spectroscopy, including line mixing effects in CO2 far wing absorption. Momentum equations are integrated using the semi-Lagrangian explicit scheme that provides high accuracy of mass and energy conservation. Due to high vertical grid resolution required by gas dynamics calculations, the model is integrated on the short time step less than one second. The model reliably repro-duces zonal superrotation, smoothly extending far below the cloud layer, tidal patterns at the cloud level and above, and non-rotating, sun-synchronous global convective cell in the upper atmosphere. One of the most interesting features of the model is the development of the polar vortices resembling those observed by Venus Express' VIRTIS instrument. Initial analysis of the simulation results confirms the hypothesis that it is thermal tides that provides main driver for the superrotation.

On Cirrus Cloud Fields Measured by the Atmospheric Infrared Sounder

NASA Technical Reports Server (NTRS)

Kahn, Brian H.; Eldering, Annmarie; Liou, Kuo Nan

2006-01-01

A viewgraph presentation showing trends in clouds measured by the Atmospheric Infrared Sounder (AIRS) is given. The topics include: 1) Trends in clouds measured by AIRS: Are they reasonable? 2) Single and multilayered cloud trends; 3) Retrievals of thin cirrus D(sub e) and tau: Single-layered cloud only; 4) Relationships between ECF, D(sub e), tau, and T(sub CLD); and 5) MODIS vs. AIRS retrievals.

Cloud and ice in the planetary scale circulation and in climate

NASA Technical Reports Server (NTRS)

Herman, G. F.; Houghton, D. D.; Kutzbach, J. E.; Suomi, V. E.

1984-01-01

The roles of the cryosphere, and of cloud-radiative interactions are investigated. The effects clouds and ice have in the climate system are examined. The cloud radiation research attempts explain the modes of interaction (feedback) between raditive transfer, cloud formation, and atmospheric dynamics. The role of sea ice in weather and climate is also discussed. Models are used to describe the ice and atmospheric dynamics under study.

Vesper - Venus Chemistry and Dynamics Orbiter - A NASA Discovery Mission Proposal: Submillimeter Investigation of Atmospheric Chemistry and Dynamics

NASA Technical Reports Server (NTRS)

Chin, Gordon

2011-01-01

Vesper conducts a focused investigation of the chemistry and dynamics of the middle atmosphere of our sister planet- from the base of the global cloud cover to the lower thermosphere. The middle atmosphere controls the stability of the Venus climate system. Vesper determines what processes maintain the atmospheric chemical stability, cause observed variability of chemical composition, control the escape of water, and drive the extreme super-rotation. The Vesper science investigation provides a unique perspective on the Earth environment due to the similarities in the middle atmosphere processes of both Venus and the Earth. Understanding key distinctions and similarities between Venus and Earth will increase our knowledge of how terrestrial planets evolve along different paths from nearly identical initial conditions.

Drivers in the Scaling Between Precipitation and Cloud Radiative Impacts in Deep Convection

NASA Astrophysics Data System (ADS)

Rapp, A. D.; Sun, L.; Smalley, K.

2017-12-01

The coupling between changes in radiation and precipitation has been demonstrated by a number of studies and suggests an important link between cloud and precipitation processes for defining climate sensitivity. Precipitation and radiative fluxes from CloudSat/CALIPSO retrieval products are used to examine the relationship between precipitation and cloud radiative impacts through two dimensionless parameters. The surface radiative cooling impact, Rc, represents the ratio of the surface shortwave cloud radiative effect to latent heating (LH) from precipitation. The atmospheric radiative heating impact, Rh, represents the ratio of the atmospheric cloud radiative effect to LH from precipitation. Together, these parameters describe the relationship between precipitation processes and how efficiently clouds cools the surface or heats the atmosphere. Deep convective clouds are identified using the 2B-GEOPROF-LIDAR joint radar-lidar product and the cloud radiative impact parameters are calculated from the 2B-FLXHR-LIDAR fluxes and 2C-RAIN-PROFILE precipitation. Deep convective clouds will be sampled according to their dynamic and thermodynamic regimes to provide insights into the factors that control the scaling between precipitation and radiative impacts. Preliminary results from analysis of precipitating deep convective pixels indicates a strong increase (decrease) in the ratio of atmospheric heating (surface cooling) and precipitation with thermodynamic environment, especially increasing water vapor; however, it remains to be seen whether these results hold when integrated over an entire deep convective cloud system. Analysis of the dependence of Rc and Rh on the cloud horizontal and vertical structure is also planned, which should lead to a better understanding of the role of non-precipitating anvil characteristics in modulating the relationship between precipitation and surface and atmospheric radiative effects.

Physically-Retrieving Cloud and Thermodynamic Parameters from Ultraspectral IR Measurements

NASA Technical Reports Server (NTRS)

Zhou, Daniel K.; Smith, William L., Sr.; Liu, Xu; Larar, Allen M.; Mango, Stephen A.; Huang, Hung-Lung

2007-01-01

A physical inversion scheme has been developed, dealing with cloudy as well as cloud-free radiance observed with ultraspectral infrared sounders, to simultaneously retrieve surface, atmospheric thermodynamic, and cloud microphysical parameters. A fast radiative transfer model, which applies to the clouded atmosphere, is used for atmospheric profile and cloud parameter retrieval. A one-dimensional (1-d) variational multi-variable inversion solution is used to improve an iterative background state defined by an eigenvector-regression-retrieval. The solution is iterated in order to account for non-linearity in the 1-d variational solution. It is shown that relatively accurate temperature and moisture retrievals can be achieved below optically thin clouds. For optically thick clouds, accurate temperature and moisture profiles down to cloud top level are obtained. For both optically thin and thick cloud situations, the cloud top height can be retrieved with relatively high accuracy (i.e., error < 1 km). NPOESS Airborne Sounder Testbed Interferometer (NAST-I) retrievals from the Atlantic-THORPEX Regional Campaign are compared with coincident observations obtained from dropsondes and the nadir-pointing Cloud Physics Lidar (CPL). This work was motivated by the need to obtain solutions for atmospheric soundings from infrared radiances observed for every individual field of view, regardless of cloud cover, from future ultraspectral geostationary satellite sounding instruments, such as the Geosynchronous Imaging Fourier Transform Spectrometer (GIFTS) and the Hyperspectral Environmental Suite (HES). However, this retrieval approach can also be applied to the ultraspectral sounding instruments to fly on Polar satellites, such as the Infrared Atmospheric Sounding Interferometer (IASI) on the European MetOp satellite, the Cross-track Infrared Sounder (CrIS) on the NPOESS Preparatory Project and the following NPOESS series of satellites.

Mesoscale to Synoptic Scale Cloud Variability

NASA Technical Reports Server (NTRS)

Rossow, William B.

1998-01-01

The atmospheric circulation and its interaction with the oceanic circulation involve non-linear and non-local exchanges of energy and water over a very large range of space and time scales. These exchanges are revealed, in part, by the related variations of clouds, which occur on a similar range of scales as the atmospheric motions that produce them. Collection of comprehensive measurements of the properties of the atmosphere, clouds and surface allows for diagnosis of some of these exchanges. The use of a multi-satellite-network approach by the International Satellite Cloud Climatology Project (ISCCP) comes closest to providing complete coverage of the relevant range space and time scales over which the clouds, atmosphere and ocean vary. A nearly 15-yr dataset is now available that covers the range from 3 hr and 30 km to decade and planetary. This paper considers three topics: (1) cloud variations at the smallest scales and how they may influence radiation-cloud interactions, and (2) cloud variations at "moderate" scales and how they may cause natural climate variability, and (3) cloud variations at the largest scales and how they affect the climate. The emphasis in this discussion is on the more mature subject of cloud-radiation interactions. There is now a need to begin similar detailed diagnostic studies of water exchange processes.

Profiling of Atmospheric Water Vapor from the SSM/T-2 Radiometric Measurements

NASA Technical Reports Server (NTRS)

Wang, J. R.

2000-01-01

An advantage of using the millimeter-wave measurements for water vapor profiling is the ability to probe beyond a moderate cloud cover. Such a capability has been demonstrated from an airborne MIR (Millimeter-wave Imaging Radiometer) flight over the Pacific Ocean during an intense observation period of TOGA/COARE (Tropical Ocean Global Atmosphere/ Couple Ocean Atmospheric Response Experiment) in early 1993. A Cloud Lidar System (CLS) and MODIS Airborne Simulator (MAS) were on board the same aircraft to identify the presence of clouds and cloud type. The retrieval algorithm not only provides output of a water vapor profile, but also the cloud liquid water and approximate cloud altitude required to satisfy convergence of the retrieval. The validity of these cloud parameters has not been verified previously. In this document, these cloud parameters are compared with those derived from concurrent measurements from the CLS and AMPR (Advanced Microwave Precipitation Radiometer).

(abstract) Cometary Particles as a Tracer of Jupiter's Stratospheric Circulation

NASA Technical Reports Server (NTRS)

West, R. A.; Friedson, A. J.

1993-01-01

The impact of fragments of comet Shoemaker-Levy 9 on Jupiter's atmosphere in July 1994 may provide an unprecedented opportunity to study Jupiter's stratospheric circulation. Recent calculations by Z. Sekanina predict that much of the comet material will be deposited in Jupiter's stratosphere. If so, and if the material is deposited in a confined region (10 000 km or less, horizontally) we can expect a situation analogous to an El Chichon or Pinatubo event for the terrestrial stratosphere. Initially the volatile material will be vaporized and will rapidly recondense. The large ice crystals and dust particles will rain out and be lost to the troposphere. The cloud of small particles which remain may have settling times of more than a year. These submicron to micron particles would probably be easily seen in methane filter images in the near-IR, and possibly in the ultraviolet. An observational program to monitor the dispersal of this cloud or clouds would reveal much about the nature of the circulation. Some predictions about the meridional evolution of the clouds can be made already, based on the meridional circulation model of West et al. unless the impact itself significantly disrupts the annual average circulation well after the initial transients die away.

Formation of Silicate and Titanium Clouds on Hot Jupiters

NASA Astrophysics Data System (ADS)

Powell, Diana; Zhang, Xi; Gao, Peter; Parmentier, Vivien

2018-06-01

We present the first application of a bin-scheme microphysical and vertical transport model to determine the size distribution of titanium and silicate cloud particles in the atmospheres of hot Jupiters. We predict particle size distributions from first principles for a grid of planets at four representative equatorial longitudes, and investigate how observed cloud properties depend on the atmospheric thermal structure and vertical mixing. The predicted size distributions are frequently bimodal and irregular in shape. There is a negative correlation between the total cloud mass and equilibrium temperature as well as a positive correlation between the total cloud mass and atmospheric mixing. The cloud properties on the east and west limbs show distinct differences that increase with increasing equilibrium temperature. Cloud opacities are roughly constant across a broad wavelength range, with the exception of features in the mid-infrared. Forward-scattering is found to be important across the same wavelength range. Using the fully resolved size distribution of cloud particles as opposed to a mean particle size has a distinct impact on the resultant cloud opacities. The particle size that contributes the most to the cloud opacity depends strongly on the cloud particle size distribution. We predict that it is unlikely that silicate or titanium clouds are responsible for the optical Rayleigh scattering slope seen in many hot Jupiters. We suggest that cloud opacities in emission may serve as sensitive tracers of the thermal state of a planet’s deep interior through the existence or lack of a cold trap in the deep atmosphere.

Cloud Radiation Forcings and Feedbacks: General Circulation Model Tests and Observational Validation

NASA Technical Reports Server (NTRS)

Lee,Wan-Ho; Iacobellis, Sam F.; Somerville, Richard C. J.

1997-01-01

Using an atmospheric general circulation model (the National Center for Atmospheric Research Community Climate Model: CCM2), the effects on climate sensitivity of several different cloud radiation parameterizations have been investigated. In addition to the original cloud radiation scheme of CCM2, four parameterizations incorporating prognostic cloud water were tested: one version with prescribed cloud radiative properties and three other versions with interactive cloud 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, middle, and low cloud to the total cloud radiative forcing, as well as the contributions of water vapor, temperature, and cloud to the net climate feedback. The high cloud net radiative forcing is positive, and the middle and low cloud net radiative forcings are negative. The total net cloud forcing is negative in all of the model versions. The effect of interactive cloud radiative properties on global climate sensitivity is significant. The net cloud radiative feedbacks consist of quite different shortwave and longwave components between the schemes with interactive cloud radiative properties and the schemes with specified properties. The increase in cloud water content in the warmer climate leads to optically thicker middle- and low-level clouds and in turn to negative shortwave feedbacks for the interactive radiative schemes, while the decrease in cloud amount simply produces a positive shortwave feedback for the schemes with a specified cloud 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 cloud radiation parameterizations are empirically validated by using a single-column diagnostic model. together with measurements from the Atmospheric Radiation Measurement program and from the Tropical Ocean Global Atmosphere Combined Ocean-Atmosphere Response Experiment. The inclusion of prognostic cloud water produces a notable improvement in the realism of the parameterizations, as judged by these observations. Furthermore, the observational evidence suggests that deriving cloud radiative properties from cloud water content and microphysical characteristics is a promising route to further improvement.

Influence of Ice Cloud Microphysics on Imager-Based Estimates of Earth's Radiation Budget

NASA Astrophysics Data System (ADS)

Loeb, N. G.; Kato, S.; Minnis, P.; Yang, P.; Sun-Mack, S.; Rose, F. G.; Hong, G.; Ham, S. H.

2016-12-01

A central objective of the Clouds and the Earth's Radiant Energy System (CERES) is to produce a long-term global climate data record of Earth's radiation budget from the TOA down to the surface along with the associated atmospheric and surface properties that influence it. CERES relies on a number of data sources, including broadband radiometers measuring incoming and reflected solar radiation and OLR, high-resolution spectral imagers, meteorological, aerosol and ozone assimilation data, and snow/sea-ice maps based on microwave radiometer data. While the TOA radiation budget is largely determined directly from accurate broadband radiometer measurements, the surface radiation budget is derived indirectly through radiative transfer model calculations initialized using imager-based cloud and aerosol retrievals and meteorological assimilation data. Because ice cloud particles exhibit a wide range of shapes, sizes and habits that cannot be independently retrieved a priori from passive visible/infrared imager measurements, assumptions about the scattering properties of ice clouds are necessary in order to retrieve ice cloud optical properties (e.g., optical depth) from imager radiances and to compute broadband radiative fluxes. This presentation will examine how the choice of an ice cloud particle model impacts computed shortwave (SW) radiative fluxes at the top-of-atmosphere (TOA) and surface. The ice cloud particle models considered correspond to those from prior, current and future CERES data product versions. During the CERES Edition2 (and Edition3) processing, ice cloud particles were assumed to be smooth hexagonal columns. In the Edition4, roughened hexagonal columns are assumed. The CERES team is now working on implementing in a future version an ice cloud particle model comprised of a two-habit ice cloud model consisting of roughened hexagonal columns and aggregates of roughened columnar elements. In each case, we use the same ice particle model in both the imager-based cloud retrievals (inverse problem) and the computed radiative fluxes (forward calculation). In addition to comparing radiative fluxes using the different ice cloud particle models, we also compare instantaneous TOA flux calculations with those observed by the CERES instrument.

Time-dependent buoyant puff model for explosive sources

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kansa, E.J.

1997-01-01

Several models exist to predict the time dependent behavior of bouyant puffs that result from explosions. This paper presents a new model that is derived from the strong conservative form of the conservation partial differential equations that are integrated over space to yield a coupled system of time dependent nonlinear ordinary differential equations. This model permits the cloud to evolve from an intial spherical shape not an ellipsoidal shape. It ignores the Boussinesq approximation, and treats the turbulence that is generated by the puff itself and the ambient atmospheric tubulence as separate mechanisms in determining the puff history. The puffmore » cloud rise history was found to depend no only on the mass and initial temperature of the explosion, but also upon the stability conditions of the ambient atmosphere. This model was calibrated by comparison with the Roller Coaster experiments.« less

Microwave (SSM/I) Estimates of the Precipitation Rate to Improve Numerical Atmospheric Model Forecasts

NASA Technical Reports Server (NTRS)

Raymond, William H.; Olson, William S.

1990-01-01

Delay in the spin-up of precipitation early in numerical atmospheric forecasts is a deficiency correctable by diabatic initialization combined with diabatic forcing. For either to be effective requires some knowledge of the magnitude and vertical placement of the latent heating fields. Until recently the best source of cloud and rain water data was the remotely sensed vertical integrated precipitation rate or liquid water content. Vertical placement of the condensation remains unknown. Some information about the vertical distribution of the heating rates and precipitating liquid water and ice can be obtained from retrieval techniques that use a physical model of precipitating clouds to refine and improve the interpretation of the remotely sensed data. A description of this procedure and an examination of its 3-D liquid water products, along with improved modeling methods that enhance or speed-up storm development is discussed.

Using ISCCP Weather States to Decompose Cloud Radiative Effects

NASA Technical Reports Server (NTRS)

Oreopoulos, L.; Rossow, W. B.

2012-01-01

The presentation will examine the shortwave (SW) and longwave (LW) cloud radiative effect CRE (aka "cloud radiative forcing") at the top-of-the-atmosphere and surface of ISCCP weather states (aka "cloud regimes") in three distinct geographical zones, one tropical and two mid-latitude. Our goal is to understand and quantify the contribution of the different cloud regimes to the planetary radiation budget. In the tropics we find that the three most convectively active states are the ones with largest SW, LW and net TOA CRE contributions to the overall daytime tropical CRE budget. They account for 59%, 71% and 55% of the total CRE, respectively. The boundary layer-dominated weather states account for only 34% of the total SW CRE and 41% of the total net CRE, so to focus only on them in cloud feedback studies may be imprudent. We also find that in both the northern and southern midlatitude zones only two weather states, the first and third most convectively active with large amounts of nimbostratus-type clouds, contribute ",40% to both the SW and net TOA CRE budgets, highlighting the fact that cloud regimes associated with frontal systems are not only important for weather (precipitation) but also for climate (radiation budget). While all cloud regimes in all geographical zones have a slightly larger SFC than TOA SW CRE, implying cooling of the surface and slight warming of the atmosphere, their LW radiative effects are more subtle: in the tropics the weather states with plentiful high clouds warm the atmosphere while those with copious amounts of low clouds cool the atmosphere. In both midlatitude zones only the weather states with peak cloud fractions at levels above 440 mbar warm the atmosphere while all the rest cool it. These results make the connection of the contrasting CRE effects to the atmospheric dynamics more explicit - "storms" tend to warm the atmosphere whereas fair weather clouds cool it, suggesting a positive feedback of clouds on weather systems. The breakdown of CRE by cloud regime are however not entirely similar between the two midlatitude zones. Despite the existence of an additional state in the nort!lern midlatitudes, only four weather states have net daytime CREs with absolute values above 100 Watts per square meter compared to six in the south. This reminds us that the environment where clouds occur also has a crucial role in determining their radiative effects. All the above make evident that reproducing grand averages of current CRE by climate models in only part of the challenge. If existing cloud regimes and shifts in their distributions and frequency of occurrence in a changed climate are not properly simulated, the radiative role of clouds will not be adequately predicted.

Cloud Chemistry in the United States: Problems and Prospects

NASA Astrophysics Data System (ADS)

Carlton, A. G.; Barth, M. C.; Lance, S.; Fahey, K.; McNeill, V. F.; Weber, R. J.

2017-12-01

Clouds cover 60% of the Earth's surface at a given time and are the primary means by which atmospheric trace species are lofted from the polluted boundary layer to the free troposphere. Clouds also play an important role as atmospheric aqueous phase reactors, scavenging soluble gas phase precursors and providing a medium for oxidation reactions that yield lower volatility products that contribute to increased aerosol mass when cloud drops evaporate. On a global average, most sulfate particles are formed during cloud processing, and organic particles known to form through aqueous phase pathways are found above clouds. However, atmospheric chemistry observations are generally biased for clear sky conditions. For example, aircraft field deployments typically avoid clouds. Satellite retrievals impacted by clouds are often screened from the final data products. This hinders knowledge of cloud chemistry and the impacts on tropospheric composition. In this work, we explore temporal and geospatial trends in trace species related to cloud processing in the U.S. with a focus on organic chemistry. We apply 3-dimensional and 0-dimensional models to recent campaigns and mountaintop cloud sampling sites, and compare to measurements.

Ash cloud aviation advisories

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sullivan, T.J.; Ellis, J.S.; Schalk, W.W.

1992-06-25

During the recent (12--22 June 1991) Mount Pinatubo volcano eruptions, the US Air Force Global Weather Central (AFGWC) requested assistance of the US Department of Energy`s Atmospheric Release Advisory Capability (ARAC) in creating volcanic ash cloud aviation advisories for the region of the Philippine Islands. Through application of its three-dimensional material transport and diffusion models using AFGWC meteorological analysis and forecast wind fields ARAC developed extensive analysis and 12-hourly forecast ash cloud position advisories extending to 48 hours for a period of five days. The advisories consisted of ``relative`` ash cloud concentrations in ten layers (surface-5,000 feet, 5,000--10,000 feet andmore » every 10,000 feet to 90,000 feet). The ash was represented as a log-normal size distribution of 10--200 {mu}m diameter solid particles. Size-dependent ``ashfall`` was simulated over time as the eruption clouds dispersed. Except for an internal experimental attempt to model one of the Mount Redoubt, Alaska, eruptions (12/89), ARAC had no prior experience in modeling volcanic eruption ash hazards. For the cataclysmic eruption of 15--16 June, the complex three-dimensional atmospheric structure of the region produced dramatically divergent ash cloud patterns. The large eruptions (> 7--10 km) produced ash plume clouds with strong westward transport over the South China Sea, Southeast Asia, India and beyond. The low-level eruptions (< 7 km) and quasi-steady-state venting produced a plume which generally dispersed to the north and east throughout the support period. Modeling the sequence of eruptions presented a unique challenge. Although the initial approach proved viable, further refinement is necessary and possible. A distinct need exists to quantify eruptions consistently such that ``relative`` ash concentrations relate to specific aviation hazard categories.« less

3D ADAPTIVE MESH REFINEMENT SIMULATIONS OF THE GAS CLOUD G2 BORN WITHIN THE DISKS OF YOUNG STARS IN THE GALACTIC CENTER

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schartmann, M.; Ballone, A.; Burkert, A.

The dusty, ionized gas cloud G2 is currently passing the massive black hole in the Galactic Center at a distance of roughly 2400 Schwarzschild radii. We explore the possibility of a starting point of the cloud within the disks of young stars. We make use of the large amount of new observations in order to put constraints on G2's origin. Interpreting the observations as a diffuse cloud of gas, we employ three-dimensional hydrodynamical adaptive mesh refinement (AMR) simulations with the PLUTO code and do a detailed comparison with observational data. The simulations presented in this work update our previously obtainedmore » results in multiple ways: (1) high resolution three-dimensional hydrodynamical AMR simulations are used, (2) the cloud follows the updated orbit based on the Brackett-γ data, (3) a detailed comparison to the observed high-quality position–velocity (PV) diagrams and the evolution of the total Brackett-γ luminosity is done. We concentrate on two unsolved problems of the diffuse cloud scenario: the unphysical formation epoch only shortly before the first detection and the too steep Brackett-γ light curve obtained in simulations, whereas the observations indicate a constant Brackett-γ luminosity between 2004 and 2013. For a given atmosphere and cloud mass, we find a consistent model that can explain both, the observed Brackett-γ light curve and the PV diagrams of all epochs. Assuming initial pressure equilibrium with the atmosphere, this can be reached for a starting date earlier than roughly 1900, which is close to apo-center and well within the disks of young stars.« less

A physically-based approach of treating dust-water cloud interactions in climate models

NASA Astrophysics Data System (ADS)

Kumar, P.; Karydis, V.; Barahona, D.; Sokolik, I. N.; Nenes, A.

2011-12-01

All aerosol-cloud-climate assessment studies to date assume that the ability of dust (and other insoluble species) to act as a Cloud Condensation Nuclei (CCN) is determined solely by their dry size and amount of soluble material. Recent evidence however clearly shows that dust can act as efficient CCN (even if lacking appreciable amounts of soluble material) through adsorption of water vapor onto the surface of the particle. This "inherent" CCN activity is augmented as the dust accumulates soluble material through atmospheric aging. A comprehensive treatment of dust-cloud interactions therefore requires including both of these sources of CCN activity in atmospheric models. This study presents a "unified" theory of CCN activity that considers both effects of adsorption and solute. The theory is corroborated and constrained with experiments of CCN activity of mineral aerosols generated from clays, calcite, quartz, dry lake beds and desert soil samples from Northern Africa, East Asia/China, and Northern America. The unified activation theory then is included within the mechanistic droplet activation parameterization of Kumar et al. (2009) (including the giant CCN correction of Barahona et al., 2010), for a comprehensive treatment of dust impacts on global CCN and cloud droplet number. The parameterization is demonstrated with the NASA Global Modeling Initiative (GMI) Chemical Transport Model using wind fields computed with the Goddard Institute for Space Studies (GISS) general circulation model. References Barahona, D. et al. (2010) Comprehensively Accounting for the Effect of Giant CCN in Cloud Activation Parameterizations, Atmos.Chem.Phys., 10, 2467-2473 Kumar, P., I.N. Sokolik, and A. Nenes (2009), Parameterization of cloud droplet formation for global and regional models: including adsorption activation from insoluble CCN, Atmos.Chem.Phys., 9, 2517- 2532

Parameter Uncertainty on AGCM-simulated Tropical Cyclones

NASA Astrophysics Data System (ADS)

He, F.

2015-12-01

This work studies the parameter uncertainty on tropical cyclone (TC) simulations in Atmospheric General Circulation Models (AGCMs) using the Reed-Jablonowski TC test case, which is illustrated in Community Atmosphere Model (CAM). It examines the impact from 24 parameters across the physical parameterization schemes that represent the convection, turbulence, precipitation and cloud processes in AGCMs. The one-at-a-time (OAT) sensitivity analysis method first quantifies their relative importance on TC simulations and identifies the key parameters to the six different TC characteristics: intensity, precipitation, longwave cloud radiative forcing (LWCF), shortwave cloud radiative forcing (SWCF), cloud liquid water path (LWP) and ice water path (IWP). Then, 8 physical parameters are chosen and perturbed using the Latin-Hypercube Sampling (LHS) method. The comparison between OAT ensemble run and LHS ensemble run shows that the simulated TC intensity is mainly affected by the parcel fractional mass entrainment rate in Zhang-McFarlane (ZM) deep convection scheme. The nonlinear interactive effect among different physical parameters is negligible on simulated TC intensity. In contrast, this nonlinear interactive effect plays a significant role in other simulated tropical cyclone characteristics (precipitation, LWCF, SWCF, LWP and IWP) and greatly enlarge their simulated uncertainties. The statistical emulator Extended Multivariate Adaptive Regression Splines (EMARS) is applied to characterize the response functions for nonlinear effect. Last, we find that the intensity uncertainty caused by physical parameters is in a degree comparable to uncertainty caused by model structure (e.g. grid) and initial conditions (e.g. sea surface temperature, atmospheric moisture). These findings suggest the importance of using the perturbed physics ensemble (PPE) method to revisit tropical cyclone prediction under climate change scenario.

Cloud and Aerosol Retrieval for the 2001 GLAS Satellite Lidar Mission

NASA Technical Reports Server (NTRS)

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

2000-01-01

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

Photochemistry of aqueous pyruvic acid

PubMed Central

Griffith, Elizabeth C.; Carpenter, Barry K.; Shoemaker, Richard K.; Vaida, Veronica

2013-01-01

The study of organic chemistry in atmospheric aerosols and cloud formation is of interest in predictions of air quality and climate change. It is now known that aqueous phase chemistry is important in the formation of secondary organic aerosols. Here, the photoreactivity of pyruvic acid (PA; CH3COCOOH) is investigated in aqueous environments characteristic of atmospheric aerosols. PA is currently used as a proxy for α-dicarbonyls in atmospheric models and is abundant in both the gas phase and the aqueous phase (atmospheric aerosols, fog, and clouds) in the atmosphere. The photoreactivity of PA in these phases, however, is very different, thus prompting the need for a mechanistic understanding of its reactivity in different environments. Although the decarboxylation of aqueous phase PA through UV excitation has been studied for many years, its mechanism and products remain controversial. In this work, photolysis of aqueous PA is shown to produce acetoin (CH3CHOHCOCH3), lactic acid (CH3CHOHCOOH), acetic acid (CH3COOH), and oligomers, illustrating the progression from a three-carbon molecule to four-carbon and even six-carbon molecules through direct photolysis. These products are detected using vibrational and electronic spectroscopy, NMR, and MS, and a reaction mechanism is presented accounting for all products detected. The relevance of sunlight-initiated PA chemistry in aqueous environments is then discussed in the context of processes occurring on atmospheric aerosols. PMID:23821751

Initiation of secondary ice production in clouds

NASA Astrophysics Data System (ADS)

Sullivan, Sylvia C.; Hoose, Corinna; Kiselev, Alexei; Leisner, Thomas; Nenes, Athanasios

2018-02-01

Disparities between the measured concentrations of ice-nucleating particles (INPs) and in-cloud ice crystal number concentrations (ICNCs) have led to the hypothesis that mechanisms other than primary nucleation form ice in the atmosphere. Here, we model three of these secondary production mechanisms - rime splintering, frozen droplet shattering, and ice-ice collisional breakup - with a six-hydrometeor-class parcel model. We perform three sets of simulations to understand temporal evolution of ice hydrometeor number (Nice), thermodynamic limitations, and the impact of parametric uncertainty when secondary production is active. Output is assessed in terms of the number of primarily nucleated ice crystals that must exist before secondary production initiates (NINP(lim)) as well as the ICNC enhancement from secondary production and the timing of a 100-fold enhancement. Nice evolution can be understood in terms of collision-based nonlinearity and the phasedness of the process, i.e., whether it involves ice hydrometeors, liquid ones, or both. Ice-ice collisional breakup is the only process for which a meaningful NINP(lim) exists (0.002 up to 0.15 L-1). For droplet shattering and rime splintering, a warm enough cloud base temperature and modest updraft are the more important criteria for initiation. The low values of NINP(lim) here suggest that, under appropriate thermodynamic conditions for secondary ice production, perturbations in cloud concentration nuclei concentrations are more influential in mixed-phase partitioning than those in INP concentrations.

Large-Eddy Simulation of Shallow Cumulus over Land: A Composite Case Based on ARM Long-Term Observations at Its Southern Great Plains Site

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Yunyan; Klein, Stephen A.; Fan, Jiwen

Based on long-term observations by the Atmospheric Radiation Measurement program at its Southern Great Plains site, a new composite case of continental shallow cumulus (ShCu) convection is constructed for large-eddy simulations (LES) and single-column models. The case represents a typical daytime nonprecipitating ShCu whose formation and dissipation are driven by the local atmospheric conditions and land surface forcing and are not influenced by synoptic weather events. The case includes early morning initial profiles of temperature and moisture with a residual layer; diurnally varying sensible and latent heat fluxes, which represent a domain average over different land surface types; simplified large-scalemore » horizontal advective tendencies and subsidence; and horizontal winds with prevailing direction and average speed. Observed composite cloud statistics are provided for model evaluation. The observed diurnal cycle is well reproduced by LES; however, the cloud amount, liquid water path, and shortwave radiative effect are generally underestimated. LES are compared between simulations with an all-or-nothing bulk microphysics and a spectral bin microphysics. The latter shows improved agreement with observations in the total cloud cover and the amount of clouds with depths greater than 300 m. When compared with radar retrievals of in-cloud air motion, LES produce comparable downdraft vertical velocities, but a larger updraft area, velocity, and updraft mass flux. Both observations and LES show a significantly larger in-cloud downdraft fraction and downdraft mass flux than marine ShCu.« less

Large-Eddy Simulation of Shallow Cumulus over Land: A Composite Case Based on ARM Long-Term Observations at Its Southern Great Plains Site

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Yunyan; Klein, Stephen A.; Fan, Jiwen

Based on long-term observations by the Atmospheric Radiation Measurement program at its Southern Great Plains site, a new composite case of continental shallow cumulus (ShCu) convection is constructed for large-eddy simulations (LES) and single-column models. The case represents a typical daytime non-precipitating ShCu whose formation and dissipation are driven by the local atmospheric conditions and land-surface forcing, and are not influenced by synoptic weather events. The case includes: early-morning initial profiles of temperature and moisture with a residual layer; diurnally-varying sensible and latent heat fluxes which represent a domain average over different land-surface types; simplified large-scale horizontal advective tendencies andmore » subsidence; and horizontal winds with prevailing direction and average speed. Observed composite cloud statistics are provided for model evaluation. The observed diurnal cycle is well-reproduced by LES, however the cloud amount, liquid water path, and shortwave radiative effect are generally underestimated. LES are compared between simulations with an all-or-nothing bulk microphysics and a spectral bin microphysics. The latter shows improved agreement with observations in the total cloud cover and the amount of clouds with depths greater than 300 meters. When compared with radar retrievals of in-cloud air motion, LES produce comparable downdraft vertical velocities, but a larger updraft area, velocity and updraft mass flux. Finally, both observation and LES show a significantly larger in-cloud downdraft fraction and downdraft mass flux than marine ShCu.« less

Large-Eddy Simulation of Shallow Cumulus over Land: A Composite Case Based on ARM Long-Term Observations at Its Southern Great Plains Site

DOE PAGES

Zhang, Yunyan; Klein, Stephen A.; Fan, Jiwen; ...

2017-09-19

Based on long-term observations by the Atmospheric Radiation Measurement program at its Southern Great Plains site, a new composite case of continental shallow cumulus (ShCu) convection is constructed for large-eddy simulations (LES) and single-column models. The case represents a typical daytime non-precipitating ShCu whose formation and dissipation are driven by the local atmospheric conditions and land-surface forcing, and are not influenced by synoptic weather events. The case includes: early-morning initial profiles of temperature and moisture with a residual layer; diurnally-varying sensible and latent heat fluxes which represent a domain average over different land-surface types; simplified large-scale horizontal advective tendencies andmore » subsidence; and horizontal winds with prevailing direction and average speed. Observed composite cloud statistics are provided for model evaluation. The observed diurnal cycle is well-reproduced by LES, however the cloud amount, liquid water path, and shortwave radiative effect are generally underestimated. LES are compared between simulations with an all-or-nothing bulk microphysics and a spectral bin microphysics. The latter shows improved agreement with observations in the total cloud cover and the amount of clouds with depths greater than 300 meters. When compared with radar retrievals of in-cloud air motion, LES produce comparable downdraft vertical velocities, but a larger updraft area, velocity and updraft mass flux. Finally, both observation and LES show a significantly larger in-cloud downdraft fraction and downdraft mass flux than marine ShCu.« less

Biomass-Burning Aerosols in South East-Asia: Smoke Impact Assessment (BASE-ASIA)

NASA Technical Reports Server (NTRS)

Tsay, S.-C.; Hsu, N. C.; King, M. D.; Sun, W.-Y.

2004-01-01

Biomass burning has been a regular practice for land clearing and land conversion in many countries, especially those in Africa, South America, and Southeast Asia. However, the unique climatology of Southeast Asia is very different than that of Africa and South America, such that large-scale biomass burning causes smoke to interact extensively with clouds during the peak-burning season of March to April. Significant global sources of greenhouse gases (e.g., CO2, CH4), chemically active gases (e.g., NO, CO, HC, CH3Br), and atmospheric aerosols are produced by biomass burning processes. These gases influence the Earth- atmosphere system, impacting both global climate and tropospheric chemistry. Some aerosols can serve as cloud condensation nuclei, which play an important role in determining cloud lifetime and precipitation, hence, altering the earth s radiation and water budget. Analyses from satellite measurements reveal the reflected solar (emitted thermal) radiation from clouds due to smoke aerosols can be reduced (enhanced) by 100 (20) Watts per square meter over the month of March 2000. In addition, the reduction in cloud spectral reflectance is large enough to lead to significant errors in satellite retrievals of cloud properties (e.g., optical thickness and effective radius). The fresh water distribution in this region is highly dependent on monsoon rainfall; in fact, the predictability of the tropical climate system is much reduced during the boreal spring. Therefore, to accurately assess the impact of smoke aerosols in this region requires continuous observations from satellites, aircraft, ground-based networks and dedicated field experiments. BASE-ASIA initiative has been proposed and will be discussed.

Peering Deep into Jupiter Atmosphere

NASA Image and Video Library

2013-03-14

The dark hot spot in this false-color image from NASA Cassini spacecraft is a window deep into Jupiter atmosphere. All around it are layers of higher clouds, with colors indicating which layer of the atmosphere the clouds are in.

The clouds and winds of Neptune

NASA Astrophysics Data System (ADS)

Beebe, R.

1992-04-01

The atmospheric features of Neptune are described based on the images from Voyager 2 with comparisons made to the atmosphere of Uranus. Specific attention is given to the clear atmosphere's methane content and lack of the smog associated with Uranus. Neptune absorbs only a small amount of energy from sunlight and radiates about 2.7 times as much as it absorbs. The mechanisms that keep Neptune's atmosphere free of smog are thought to be upwelling enhanced by an outward heat flow and melting ice. The Voyager photographs show streaks of white clouds indicating strong winds and probably white ice in the upper atmosphere. The Great Dark Spot and a small triangular cloud are described in terms of their periods of rotation, and the wind speed is discussed in terms of cloud variations. The Great Dark Spot drifted equatorward during the observational period, and the drift yields some important clues regarding the nature of the Neptunian atmosphere and climate.

Full-Time, Eye-Safe Cloud and Aerosol Lidar Observation at Atmospheric Radiation Measurement Program Sites: Instruments and Data Analysis

NASA Technical Reports Server (NTRS)

Campbell, James R.; Hlavka, Dennis L.; Welton, Ellsworth J.; Flynn, Connor J.; Turner, David D.; Spinhirne, James D.; Scott, V. Stanley, III; Hwang, I. H.; Einaudi, Franco (Technical Monitor)

2001-01-01

Atmospheric radiative forcing, surface radiation budget, and top of the atmosphere radiance interpretation involves a knowledge of the vertical height structure of overlying cloud and aerosol layers. During the last decade, the U.S. Department of Energy through I the Atmospheric Radiation Measurement (ARM) program has constructed four long- term atmospheric observing sites in strategic climate regimes (north central Oklahoma, In Barrow. Alaska, and Nauru and Manus Islands in the tropical western Pacific). Micro Pulse Lidar (MPL) systems provide continuous, autonomous observation of all significant atmospheric cloud and aerosol at each of the central ARM facilities. Systems are compact and transmitted pulses are eye-safe. Eye-safety is achieved by expanding relatively low-powered outgoing Pulse energy through a shared, coaxial transmit/receive telescope. ARM NIPL system specifications, and specific unit optical designs are discussed. Data normalization and calibration techniques are presented. A multiple cloud boundary detection algorithm is also described. These techniques in tandem represent an operational value added processing package used to produce normalized data products for Cloud and aerosol research and the historical ARM data archive.

Atmospheric circulation of brown dwarfs and directly imaged extrasolar giant planets with active clouds

NASA Astrophysics Data System (ADS)

Tan, Xianyu; Showman, Adam

2016-10-01

Observational evidence have suggested active meteorology in the atmospheres of brown dwarfs (BDs) and directly imaged extrasolar giant planets (EGPs). In particular, a number of surveys for brown dwarfs showed that near-IR brightness variability is common for L and T dwarfs. Directly imaged EGPs share similar observations, and can be viewed as low-gravity versions of BDs. Clouds are believed to play the major role in shaping the thermal structure, dynamics and near-IR flux of these atmospheres. So far, only a few studies have been devoted to atmospheric circulation and the implications for observations of BDs and directly EGPs, and yet no global model includes a self-consistent active cloud formation. Here we present preliminary results from the first global circulation model applied to BDs and directly imaged EGPs that can properly treat absorption and scattering of radiation by cloud particles. Our results suggest that horizontal temperature differences on isobars can reach up to a few hundred Kelvins, with typical horizontal length scale of the temperature and cloud patterns much smaller than the radius of the object. The combination of temperature anomaly and cloud pattern can result in moderate disk-integrated near-IR flux variability. Wind speeds can reach several hundred meters per second in cloud forming layers. Unlike Jupiter and Saturn, we do not observe stable zonal jet/banded patterns in our simulations. Instead, our simulated atmospheres are typically turbulent and dominated by transient vortices. The circulation is sensitive to the parameterized cloud microphysics. Under some parameter combinations, global-scale atmospheric waves can be triggered and maintained. These waves induce global-scale temperature anomalies and cloud patterns, causing large (up to several percent) disk-integrated near-IR flux variability. Our results demonstrate that the commonly observed near-IR brightness variability for BDs and directly imaged EGPs can be explained by the typical cloud-induced turbulent circulation, and in particular, the large flux variability for some objects can be attributed to the global-scale patterns of temperature anomaly and cloud formation caused by atmospheric waves.

Clouds and hazes in exoplanets and brown dwarfs

NASA Astrophysics Data System (ADS)

Morley, Caroline Victoria

The formation of clouds significantly alters the spectra of cool substellar atmospheres from terrestrial planets to brown dwarfs. In cool planets like Earth and Jupiter, volatile species like water and ammonia condense to form ice clouds. In hot planets and brown dwarfs, iron and silicates instead condense, forming dusty clouds. Irradiated methane-rich planets may have substantial hydrocarbon hazes. During my dissertation, I have studied the impact of clouds and hazes in a variety of substellar objects. First, I present results for cool brown dwarfs including clouds previously neglected in model atmospheres. Model spectra that include sulfide and salt clouds can match the spectra of T dwarf atmospheres; water ice clouds will alter the spectra of the newest and coldest brown dwarfs, the Y dwarfs. These sulfide/salt and ice clouds potentially drive spectroscopic variability in these cool objects, and this variability should be distinguishable from variability caused by hot spots. Next, I present results for small, cool exoplanets between the size of Earth and Neptune. They likely have sulfide and salt clouds and also have photochemical hazes caused by stellar irradiation. Vast resources have been dedicated to characterizing the handful of super Earths and Neptunes accessible to current telescopes, yet of the planets smaller than Neptune studied to date, all have radii in the near-infrared consistent with being constant in wavelength, likely showing that these small planets are consistently enshrouded in thick hazes and clouds. For the super Earth GJ 1214b, very thick, lofted clouds of salts or sulfides in high metallicity (1000x solar) atmospheres create featureless transmission spectra in the near-infrared. Photochemical hazes also create featureless transmission spectra at lower metallicities. For the Neptune-sized GJ 436b, its thermal emission and transmission spectra combine indicate a high metallicity atmosphere, potentially heated by tides and affected by disequilibrium chemistry. I show that despite the challenges, there are promising avenues for understanding small planets: by observing thermal emission and reflected light, we can break the degeneracies and con- strain the atmospheric compositions. These future observations will provide rich diagnostics of molecules and clouds in small planets.

The Impact of Clouds and Hazes in Substellar Atmospheres

NASA Astrophysics Data System (ADS)

Morley, Caroline; Fortney, Jonathan J.; Marley, Mark S.

2016-01-01

The formation of clouds significantly alters the spectra of cool substellar atmospheres from terrestrial planets to brown dwarfs. In cool planets like Earth and Jupiter, volatile species like water and ammonia condense to form ice clouds. In hot planets and brown dwarfs, iron and silicates instead condense, forming dusty clouds. Irradiated methane-rich planets may have substantial hydrocarbon hazes. During my thesis, I have studied the impact of clouds and hazes in a variety of substellar objects. First, I present results for cool brown dwarfs including clouds previously neglected in model atmospheres. Model spectra that include sulfide and salt clouds can match the spectra of T dwarf atmospheres; water ice clouds will alter the spectra of the newest and coldest brown dwarfs, the Y dwarfs. These sulfide/salt and ice clouds potentially drive spectroscopic variability in these cool objects, and this variability should be distinguishable from variability caused by hot spots.Next, I present results for small, cool exoplanets between the size of Earth and Neptune, so-called super Earths. They likely have sulfide and salt clouds and also have photochemical hazes caused by stellar irradiation. Vast resources have been dedicated to characterizing the handful of super Earths accessible to current telescopes, yet of the planets smaller than Neptune studied to date, all have radii in the near-infrared consistent with being constant in wavelength, likely showing that these small planets are consistently enshrouded in thick hazes and clouds. Very thick, lofted clouds of salts or sulfides in high metallicity (1000× solar) atmospheres create featureless transmission spectra in the near-infrared. Photochemical hazes with a range of particle sizes also create featureless transmission spectra at lower metallicities. I show that despite these challenges, there are promising avenues for understanding this class of small planets: by observing the thermal emission and reflectivity of small planets, we can break the degeneracies and better constrain the atmospheric compositions. These observations may provide rich diagnostics of molecules and clouds in small planets, in contrast to the limited success to date.

The variability of tropical ice cloud properties as a function of the large-scale context from ground-based radar-lidar observations over Darwin, Australia

NASA Astrophysics Data System (ADS)

Protat, A.; Delanoë, J.; May, P. T.; Haynes, J.; Jakob, C.; O'Connor, E.; Pope, M.; Wheeler, M. C.

2011-08-01

The high complexity of cloud parameterizations now held in models puts more pressure on observational studies to provide useful means to evaluate them. One approach to the problem put forth in the modelling community is to evaluate under what atmospheric conditions the parameterizations fail to simulate the cloud properties and under what conditions they do a good job. It is the ambition of this paper to characterize the variability of the statistical properties of tropical ice clouds in different tropical "regimes" recently identified in the literature to aid the development of better process-oriented parameterizations in models. For this purpose, the statistical properties of non-precipitating tropical ice clouds over Darwin, Australia are characterized using ground-based radar-lidar observations from the Atmospheric Radiation Measurement (ARM) Program. The ice cloud properties analysed are the frequency of ice cloud occurrence, the morphological properties (cloud top height and thickness), and the microphysical and radiative properties (ice water content, visible extinction, effective radius, and total concentration). The variability of these tropical ice cloud properties is then studied as a function of the large-scale cloud regimes derived from the International Satellite Cloud Climatology Project (ISCCP), the amplitude and phase of the Madden-Julian Oscillation (MJO), and the large-scale atmospheric regime as derived from a long-term record of radiosonde observations over Darwin. The vertical variability of ice cloud occurrence and microphysical properties is largest in all regimes (1.5 order of magnitude for ice water content and extinction, a factor 3 in effective radius, and three orders of magnitude in concentration, typically). 98 % of ice clouds in our dataset are characterized by either a small cloud fraction (smaller than 0.3) or a very large cloud fraction (larger than 0.9). In the ice part of the troposphere three distinct layers characterized by different statistically-dominant microphysical processes are identified. The variability of the ice cloud properties as a function of the large-scale atmospheric regime, cloud regime, and MJO phase is large, producing mean differences of up to a factor 8 in the frequency of ice cloud occurrence between large-scale atmospheric regimes and mean differences of a factor 2 typically in all microphysical properties. Finally, the diurnal cycle of the frequency of occurrence of ice clouds is also very different between regimes and MJO phases, with diurnal amplitudes of the vertically-integrated frequency of ice cloud occurrence ranging from as low as 0.2 (weak diurnal amplitude) to values in excess of 2.0 (very large diurnal amplitude). Modellers should now use these results to check if their model cloud parameterizations are capable of translating a given atmospheric forcing into the correct statistical ice cloud properties.

The Mars Dust Cycle: Investigating the Effects of Radiatively Active Water Ice Clouds on Surface Stresses and Dust Lifting Potential with the NASA Ames Mars General Circulation Model

NASA Technical Reports Server (NTRS)

Kahre, Melinda A.; Hollingsworth, Jeffery

2012-01-01

The dust cycle is a critically important component of Mars' current climate system. Dust is present in the atmosphere of Mars year-round but the dust loading varies with season in a generally repeatable manner. Dust has a significant influence on the thermal structure of the atmosphere and thus greatly affects atmospheric circulation. The dust cycle is the most difficult of the three climate cycles (CO2, water, and dust) to model realistically with general circulation models. Until recently, numerical modeling investigations of the dust cycle have typically not included the effects of couplings to the water cycle through cloud formation. In the Martian atmosphere, dust particles likely provide the seed nuclei for heterogeneous nucleation of water ice clouds. As ice coats atmospheric dust grains, the newly formed cloud particles exhibit different physical and radiative characteristics. Thus, the coupling between the dust and water cycles likely affects the distributions of dust, water vapor and water ice, and thus atmospheric heating and cooling and the resulting circulations. We use the NASA Ames Mars GCM to investigate the effects of radiatively active water ice clouds on surface stress and the potential for dust lifting. The model includes a state-of-the-art water ice cloud microphysics package and a radiative transfer scheme that accounts for the radiative effects of CO2 gas, dust, and water ice clouds. We focus on simulations that are radiatively forced by a prescribed dust map, and we compare simulations that do and do not include radiatively active clouds. Preliminary results suggest that the magnitude and spatial patterns of surface stress (and thus dust lifting potential) are substantial influenced by the radiative effects of water ice clouds.

Does Wilson's cloud chamber offer clues on lightning initiation in thunderclouds?

NASA Astrophysics Data System (ADS)

Cooray, V.; Rakov, V.

2007-12-01

The experimental evidence indicates that the large scale electric field in the cloud at the time of lightning initiation is about 100 kV/m [1], which is an order of magnitude lower than the expected conventional breakdown field. One important problem in atmospheric physics is to understand how lightning flashes are initiated in such low fields. Some scientists suggest that the electric field could reach higher values momentarily in small regions and this combined with the field enhancing action of hydrometeors in the cloud could provide trigger for lightning initiation [2, 3]. Others suggest that energetic electrons produced by cosmic rays could give rise to runaway electron avalanches generating the initial ionization necessary for lightning initiation [4]. Nguyen and Michnowski [2] suggested that in small cloud regions the electric field may exceed 200 to 400 kV/m and in these locations the discharges between hydrometeors could facilitate lightning initiation. This mechanism was further investigated by Cooray et al. [3] who showed that interaction between adjacent hydrometeors cannot produce a streamer discharge, a prerequisite for electric breakdown, unless the field exceeds about 830 kV/m. They also found that long chains of hydrometeors could initiate streamer discharges in relatively low electric fields. For example, in order to generate a streamer discharge in 100 kV/m electric field the length of the chain of hydrometeors of 0.1 mm radius should be about 65 mm with more than 100 particles constituting the chain. However, the question remains on how such long chains of hydrometeors can be produced in the cloud. We suggest the following possibility. Consider an energetic particle passing through the cloud producing ionization in its wake. The passage of such a particle will lead to a stream of positive ions and electrons with the latter being captured within a few tens of nanoseconds by oxygen molecules to form negative ions. If the water vapor in the region under consideration is supersaturated, water molecules will condense on the ions and the resulting droplets can grow to tens of micrometers in a fraction of a second. This is the mechanism utilized in Wilson's cloud chamber to visualize the tracks of ionizing particles. If the track of ionizing particle is aligned with the direction of the electric field in the cloud, the resultant drift of the oppositely charged particles in opposite directions will facilitate collisions among them leading to production of larger droplets. This process can potentially generate long chains of droplets in the cloud which may provide the trigger necessary for the initiation of lightning flashes. [1] Marshall, T. C., M. P. McCarthy and W. D. Rust, Electric field magnitudes and lightning initiation in thunderstorms, J. Geophys. Res., vol. 100, pp. 7097 - 7103, 1995. [2] Nguyen, M. D. and S. Michnowski, On the initiation of lightning discharges in a cloud, 2. The lightning initiation on precipitation particles, J. Geophys. Res., vol. 101, pp. 26 675 - 26 680, 1996. [3] Cooray, V., M. Berg, M. Akyuz and A. Larsson, Initiation of ground flashes: some microscopic electrical processes associated with precipitation particles, Proc. International Conference on Lightning Protection, Birmingham, UK, 2002. [4] Gurevich, A. V., G. M. Milikh and J. A. Valdivia, Model of X-ray emission and fast preconditioning during a thunderstorm, Phys. Lett., A 231, pp. 402 - 408, 1997.

Vertical wind velocity measurements using a five-hole probe with remotely piloted aircraft to study aerosol-cloud interactions

NASA Astrophysics Data System (ADS)

Calmer, Radiance; Roberts, Gregory C.; Preissler, Jana; Sanchez, Kevin J.; Derrien, Solène; O'Dowd, Colin

2018-05-01

The importance of vertical wind velocities (in particular positive vertical wind velocities or updrafts) in atmospheric science has motivated the need to deploy multi-hole probes developed for manned aircraft in small remotely piloted aircraft (RPA). In atmospheric research, lightweight RPAs ( < 2.5 kg) are now able to accurately measure atmospheric wind vectors, even in a cloud, which provides essential observing tools for understanding aerosol-cloud interactions. The European project BACCHUS (impact of Biogenic versus Anthropogenic emissions on Clouds and Climate: towards a Holistic UnderStanding) focuses on these specific interactions. In particular, vertical wind velocity at cloud base is a key parameter for studying aerosol-cloud interactions. To measure the three components of wind, a RPA is equipped with a five-hole probe, pressure sensors, and an inertial navigation system (INS). The five-hole probe is calibrated on a multi-axis platform, and the probe-INS system is validated in a wind tunnel. Once mounted on a RPA, power spectral density (PSD) functions and turbulent kinetic energy (TKE) derived from the five-hole probe are compared with sonic anemometers on a meteorological mast. During a BACCHUS field campaign at Mace Head Atmospheric Research Station (Ireland), a fleet of RPAs was deployed to profile the atmosphere and complement ground-based and satellite observations of physical and chemical properties of aerosols, clouds, and meteorological state parameters. The five-hole probe was flown on straight-and-level legs to measure vertical wind velocities within clouds. The vertical velocity measurements from the RPA are validated with vertical velocities derived from a ground-based cloud radar by showing that both measurements yield model-simulated cloud droplet number concentrations within 10 %. The updraft velocity distributions illustrate distinct relationships between vertical cloud fields in different meteorological conditions.

W-band spaceborne radar observations of atmospheric river events

NASA Astrophysics Data System (ADS)

Matrosov, S. Y.

2010-12-01

While the main objective of the world first W-band radar aboard the CloudSat satellite is to provide vertically resolved information on clouds, it proved to be a valuable tool for observing precipitation. The CloudSat radar is generally able to resolve precipitating cloud systems in their vertical entirety. Although measurements from the liquid hydrometer layer containing rainfall are strongly attenuated, special retrieval approaches can be used to estimate rainfall parameters. These approaches are based on vertical gradients of observed radar reflectivity factor rather than on absolute estimates of reflectivity. Concurrent independent estimations of ice cloud parameters in the same vertical column allow characterization of precipitating systems and provide information on coupling between clouds and rainfall they produce. The potential of CloudSat for observations atmospheric river events affecting the West Coast of North America is evaluated. It is shown that spaceborne radar measurements can provide high resolution information on the height of the freezing level thus separating areas of rainfall and snowfall. CloudSat precipitation rate estimates complement information from the surface-based radars. Observations of atmospheric rivers at different locations above the ocean and during landfall help to understand evolutions of atmospheric rivers and their structures.

Cloud Imagers Offer New Details on Earth's Health

NASA Technical Reports Server (NTRS)

2009-01-01

A stunning red sunset or purple sunrise is an aesthetic treat with a scientific explanation: The colors are a direct result of the absorption or reflectance of solar radiation by atmospheric aerosols, minute particles (either solid or liquid) in the Earth s atmosphere that occur both naturally and because of human activity. At the beginning or end of the day, the Sun s rays travel farther through the atmosphere to reach an observer s eyes and more green and yellow light is scattered, making the Sun appear red. Sunset and sunrise are especially colorful when the concentration of atmospheric particles is high. This ability of aerosols to absorb and reflect sunlight is not just pretty; it also determines the amount of radiation and heat that reaches the Earth s surface, and can profoundly affect climate. In the atmosphere, aerosols are also important as nuclei for the condensation of water droplets and ice crystals. Clouds with fewer aerosols cannot form as many water droplets (called cloud particles), and consequently, do not scatter light well. In this case, more sunlight reaches the Earth s surface. When aerosol levels in clouds are high, however, more nucleation points can form small liquid water droplets. These smaller cloud particles can reflect up to 90 percent of visible radiation to space, keeping the heat from ever reaching Earth s surface. The tendency for these particles to absorb or reflect the Sun s energy - called extinction by astronomers - depends on a number of factors, including chemical composition and the humidity and temperature in the surrounding air; because cloud particles are so small, they are affected quickly by minute changes in the atmosphere. Because of this sensitivity, atmospheric scientists study cloud particles to anticipate patterns and shifts in climate. Until recently, NASA s study of atmospheric aerosols and cloud particles has been focused primarily on satellite images, which, while granting large-scale atmospheric analysis, limited scientists ability to acquire detailed information about individual particles. Now, experiments with specialized equipment can be flown on standard jets, making it possible for researchers to monitor and more accurately anticipate changes in Earth s atmosphere and weather patterns.

The dynamic surface tension of atmospheric aerosol surfactants reveals new aspects of cloud activation.

PubMed

Nozière, Barbara; Baduel, Christine; Jaffrezo, Jean-Luc

2014-02-25

The activation of aerosol particles into cloud droplets in the Earth's atmosphere is both a key process for the climate budget and a main source of uncertainty. Its investigation is facing major experimental challenges, as no technique can measure the main driving parameters, the Raoult's term and surface tension, σ, for sub-micron atmospheric particles. In addition, the surfactant fraction of atmospheric aerosols could not be isolated until recently. Here we present the first dynamic investigation of the total surfactant fraction of atmospheric aerosols, evidencing adsorption barriers that limit their gradient (partitioning) in particles and should enhance their cloud-forming efficiency compared with current models. The results also show that the equilibration time of surfactants in sub-micron atmospheric particles should be beyond the detection of most on-line instruments. Such instrumental and theoretical shortcomings would be consistent with atmospheric and laboratory observations and could have limited the understanding of cloud activation until now.

A Review of Spatial and Seasonal Changes in Condensation Clouds Observed During Aerobraking by MGS TES

NASA Technical Reports Server (NTRS)

Pearl, J. C.; Smith, M. D.; Conrath, B. J.; Bandfield, J. L.; Christensen, P. R.

1999-01-01

Successful operation of the Mars Global Surveyor spacecraft, beginning in September 1997, has permitted extensive infrared observations of condensation clouds during the martian southern summer and fall seasons (184 deg less than L(sub s) less than 28 deg). Initially, thin (normal optical depth less than 0.06 at 825/ cm) ice clouds and hazes were widespread, showing a latitudinal gradient. With the onset of a regional dust storm at L(sub s) = 224 deg, ice clouds essentially vanished in the southern hemisphere, to reappear gradually after the decay of the storm. The thickest clouds (optical depth approx. 0.6) were associated with major volcanic features. At L(exp s) = 318 deg, the cloud at Ascraeus Mons was observed to disappear between 21:30 and 09:30, consistent with historically recorded diurnal behavior for clouds of this type. Limb observations showed extended optically thin (depth less than 0.04) stratiform clouds at altitudes up to 55 km. A water ice haze was present in the north polar night at altitudes up to 40 km; this probably provided heterogeneous nucleation sites for the formation of CO2 clouds at altitudes below the 1 mbar pressure level, where atmospheric temperatures dropped to the condensation point of CO2.

Critical Mechanisms for the Formation of Extreme Arctic Sea-Ice Extent in the Summers of 2007 and 1996

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dong, Xiquan; Zib, Benjamin J.; Xi, Baike

A warming Arctic climate is undergoing significant e 21 nvironmental change, most evidenced by the reduction of Arctic sea-ice extent during the summer. In this study, we examine two extreme anomalies of September sea-ice extent in 2007 and 1996, and investigate the impacts of cloud fraction (CF), atmospheric precipitable water vapor (PWV), downwelling longwave flux (DLF), surface air temperature (SAT), pressure and winds on the sea-ice variation in 2007 and 1996 using both satellite-derived sea-ice products and MERRA reanalysis. The area of the Laptev, East Siberian and West Chukchi seas (70-90oN, 90-180oE) has experienced the largest variation in sea-ice extentmore » from year-to-year and defined here as the Area Of Focus (AOF). The record low September sea-ice extent in 2007 was associated with positive anomalies 30 of CF, PWV, DLF, and SAT over the AOF. Persistent anti-cyclone positioned over the Beaufort Sea coupled with low pressure over Eurasia induced easterly zonal and southerly meridional winds. In contrast, negative CF, PWV, DLF and SAT anomalies, as well as opposite wind patterns to those in 2007, characterized the 1996 high September sea-ice extent. Through this study, we hypothesize the following positive feedbacks of clouds, water vapor, radiation and atmospheric variables on the sea-ice retreat during the summer 2007. The record low sea-ice extent during the summer 2007 is initially triggered by the atmospheric circulation anomaly. The southerly winds across the Chukchi and East Siberian seas transport warm, moist air from the north Pacific, which is not only enhancing sea-ice melt across the AOF, but also increasing clouds. The positive cloud feedback results in higher SAT and more sea-ice melt. Therefore, 40 more water vapor could be evaporated from open seas and higher SAT to form more clouds, which will enhance positive cloud feedback. This enhanced positive cloud feedback will then further increase SAT and accelerate the sea-ice retreat during the summer 2007.« less

Atmospheric State, Cloud Microphysics and Radiative Flux

DOE Data Explorer

Mace, Gerald

2008-01-15

Atmospheric thermodynamics, cloud properties, radiative fluxes and radiative heating rates for the ARM Southern Great Plains (SGP) site. The data represent a characterization of the physical state of the atmospheric column compiled on a five-minute temporal and 90m vertical grid. Sources for this information include raw measurements, cloud property and radiative retrievals, retrievals and derived variables from other third-party sources, and radiative calculations using the derived quantities.

Evaluating aerosol influence on cloud models using in-situ measurements during the INUPIAQ campaign

NASA Astrophysics Data System (ADS)

Farrington, R.; Connolly, P.; Choularton, T.; Bower, K.; Lloyd, G.; Flynn, M.; Crosier, J.; Field, P.

2014-12-01

At temperatures between -35°C and 0°C, the presence of insoluble aerosols acting as ice nuclei (IN) initiate the nucleation of ice under atmospheric conditions. Previous field and laboratory campaigns have suggested that mineral dust present in the atmosphere act as IN at temperatures around -20°C (e.g. Sassen et al. 2003), however the cause of ice nucleation at temperatures of around -5°C is less certain. Coupled with the limited representation of aerosol and cloud processes in large-scale weather and climate models, the need for improved in-situ measurements of aerosol properties and cloud micro-physical processes to drive the improvement of aerosol-clouds processes in models is evident. As part of the Ice NUcleation Process Investigation and Quantification (INUPIAQ) project, two field campaigns were conducted in early 2013 and early 2014. Both campaigns included measurements of cloud micro-physical properties at the summit of Jungfraujoch in Switzerland (3580m asl). Using data from the 2013 campaign and modelling simulations from the Weather Research and Forecasting model (WRF), an upwind site, located at Schilthorn (2970m asl), was determined for measuring aerosol properties out of cloud during the 2014 campaign. Further measurements of the cloud and aerosols properties were taken remotely using a doppler LiDAR located at Kleine Scheidegg (2061m asl). The aim of this project is to determine whether detailed aerosol information is important to determining cloud and precipitation properties downwind. To this end WRF was run using the aerosol number concentrations and size distributions measured at the Schilthorn site to compare modelled ice number concentrations with measurements taken at Jungfraujoch using state of the science cloud ice probes, including the Three-View Cloud Particle Imager (3V-CPI) and the Cloud Aerosol Spectrometer with Depolarization (CAS-DPOL), with the results of the comparison presented and discussed at this meeting. ReferencesSassen, K., et al, 2003: Saharan dust storms and indirect aerosol effects on clouds: Crystal-face results. Geophys. Res. Lett., 30(12), 1633-1636.

Effects of 3-D clouds on atmospheric transmission of solar radiation: Cloud type dependencies inferred from A-train satellite data

NASA Astrophysics Data System (ADS)

Ham, Seung-Hee; Kato, Seiji; Barker, Howard W.; Rose, Fred G.; Sun-Mack, Sunny

2014-01-01

Three-dimensional (3-D) effects on broadband shortwave top of atmosphere (TOA) nadir radiance, atmospheric absorption, and surface irradiance are examined using 3-D cloud fields obtained from one hour's worth of A-train satellite observations and one-dimensional (1-D) independent column approximation (ICA) and full 3-D radiative transfer simulations. The 3-D minus ICA differences in TOA nadir radiance multiplied by π, atmospheric absorption, and surface downwelling irradiance, denoted as πΔI, ΔA, and ΔT, respectively, are analyzed by cloud type. At the 1 km pixel scale, πΔI, ΔA, and ΔT exhibit poor spatial correlation. Once averaged with a moving window, however, better linear relationships among πΔI, ΔA, and ΔT emerge, especially for moving windows larger than 5 km and large θ0. While cloud properties and solar geometry are shown to influence the relationships amongst πΔI, ΔA, and ΔT, once they are separated by cloud type, their linear relationships become much stronger. This suggests that ICA biases in surface irradiance and atmospheric absorption can be approximated based on ICA biases in nadir radiance as a function of cloud type.

Sonora: A New Generation Model Atmosphere Grid for Brown Dwarfs and Young Extrasolar Giant Planets

NASA Astrophysics Data System (ADS)

Marley, Mark S.; Saumon, Didier; Fortney, Jonathan J.; Morley, Caroline; Lupu, Roxana E.; Freedman, Richard; Visscher, Channon

2017-06-01

Brown dwarf and giant planet atmospheric structure and composition has been studied both by forward models and, increasingly so, by retrieval methods. While indisputably informative, retrieval methods are of greatest value when judged in the context of grid model predictions. Meanwhile retrieval models can test the assumptions inherent in the forward modeling procedure.In order to provide a new, systematic survey of brown dwarf atmospheric structure, emergent spectra, and evolution, we have constructed a new grid of brown dwarf model atmospheres. We ultimately aim for our grid to span substantial ranges of atmospheric metallilcity, C/O ratios, cloud properties, atmospheric mixing, and other parameters. Spectra predicted by our modeling grid can be compared to both observations and retrieval results to aid in the interpretation and planning of future telescopic observations.We thus present Sonora, a new generation of substellar atmosphere models, appropriate for application to studies of L, T, and Y-type brown dwarfs and young extrasolar giant planets. The models describe the expected temperature-pressure profile and emergent spectra of an atmosphere in radiative-convective equilibrium for ranges of effective temperatures and gravities encompassing 200 ≤ Teff ≤ 2400 K and 2.5 ≤ log g ≤ 5.5. In our poster we briefly describe our modeling methodology, enumerate various updates since our group's previous models, and present our initial tranche of models for cloudless, solar metallicity, and solar carbon-to-oxygen ratio, chemical equilibrium atmospheres. These models will be available online and will be updated as opacities and cloud modeling methods continue to improve.

Aerosol-Induced Changes of Convective Cloud Anvils Produce Strong Climate Warming

NASA Technical Reports Server (NTRS)

Koren, I.; Remer, L. A.; Altaratz, O.; Martins, J. V.; Davidi, A.

2010-01-01

The effect of aerosol on clouds poses one of the largest uncertainties in estimating the anthropogenic contribution to climate change. Small human-induced perturbations to cloud characteristics via aerosol pathways can create a change in the top-of-atmosphere radiative forcing of hundreds of Wm(exp-2) . Here we focus on links between aerosol and deep convective clouds of the Atlantic and Pacific Intertropical Convergence Zones, noting that the aerosol environment in each region is entirely different. The tops of these vertically developed clouds consisting of mostly ice can reach high levels of the atmosphere, overshooting the lower stratosphere and reaching altitudes greater than 16 km. We show a link between aerosol, clouds and the free atmosphere wind profile that can change the magnitude and sign of the overall climate radiative forcing. We find that increased aerosol loading is associated with taller cloud towers and anvils. The taller clouds reach levels of enhanced wind speeds that act to spread and thin the anvi1 clouds, increasing areal coverage and decreasing cloud optical depth. The radiative effect of this transition is to create a positive radiative forcing (warming) at top-of-atmosphere. Furthermore we introduce the cloud optical depth (r), cloud height (Z) forcing space and show that underestimation of radiative forcing is likely to occur in cases of non homogenous clouds. Specifically, the mean radiative forcing of towers and anvils in the same scene can be several times greater than simply calculating the forcing from the mean cloud optical depth in the scene. Limitations of the method are discussed, alternative sources of aerosol loading are tested and meteorological variance is restricted, but the trend of taller clouds; increased and thinner anvils associated with increased aerosol loading remains robust through all the different tests and perturbations.

A Ten-Year Global Record of Absorbing Aerosols Above Clouds from OMI's Near-UV Observations

NASA Technical Reports Server (NTRS)

Jethva, Hiren; Torres, Omar; Ahn, Changwoo

2016-01-01

Aerosol-cloud interaction continues to be one of the leading uncertain components of climate models, primarily due to the lack of an adequate knowledge of the complex microphysical and radiative processes associated with the aerosol-cloud system. The situations when aerosols and clouds are found in the same atmospheric column, for instance, when light-absorbing aerosols such as biomass burning generated carbonaceous particles or wind-blown dust overlay low-level cloud decks, are commonly found over several regional of the world. Contrary to the cloud-free scenario over dark surface, for which aerosols are known to produce a net cooling effect (negative radiative forcing) on climate, the overlapping situation of absorbing aerosols over cloud can potentially exert a significant level of atmospheric absorption and produces a positive radiative forcing at top-of-atmosphere. The magnitude of direct radiative effects of aerosols above cloud depends directly on the aerosol loading, microphysical-optical properties of the aerosol layer and the underlying cloud deck, and geometric cloud fraction. We help in addressing this problem by introducing a novel product of optical depth of absorbing aerosols above clouds retrieved from near-UV observations made by the Ozone Monitoring Instrument (OMI) on board NASA's Aura platform. The presence of absorbing aerosols above cloud reduces the upwelling radiation reflected by cloud and produces a strong 'color ratio' effect in the near-UV region, which can be unambiguously detected in the OMI measurements. Physically based on this effect, the OMACA algorithm retrieves the optical depths of aerosols and clouds simultaneously under a prescribed state of atmosphere. The algorithm architecture and results from a ten-year global record including global climatology of frequency of occurrence and above-cloud aerosol optical depth, and a discussion on related future field campaigns are presented.

Zero-Gravity Atmospheric Cloud Physics Experiment Laboratory engineering concepts/design tradeoffs. Volume 1: Study results

NASA Technical Reports Server (NTRS)

Greco, R. V.; Eaton, L. R.; Wilkinson, H. C.

1974-01-01

The work is summarized which was accomplished from January 1974 to October 1974 for the Zero-Gravity Atmospheric Cloud Physics Laboratory. The definition and development of an atmospheric cloud physics laboratory and the selection and delineation of candidate experiments that require the unique environment of zero gravity or near zero gravity are reported. The experiment program and the laboratory concept for a Spacelab payload to perform cloud microphysics research are defined. This multimission laboratory is planned to be available to the entire scientific community to utilize in furthering the basic understanding of cloud microphysical processes and phenomenon, thereby contributing to improved weather prediction and ultimately to provide beneficial weather control and modification.

The operational cloud retrieval algorithms from TROPOMI on board Sentinel-5 Precursor

NASA Astrophysics Data System (ADS)

Loyola, Diego G.; Gimeno García, Sebastián; Lutz, Ronny; Argyrouli, Athina; Romahn, Fabian; Spurr, Robert J. D.; Pedergnana, Mattia; Doicu, Adrian; Molina García, Víctor; Schüssler, Olena

2018-01-01

This paper presents the operational cloud retrieval algorithms for the TROPOspheric Monitoring Instrument (TROPOMI) on board the European Space Agency Sentinel-5 Precursor (S5P) mission scheduled for launch in 2017. Two algorithms working in tandem are used for retrieving cloud properties: OCRA (Optical Cloud Recognition Algorithm) and ROCINN (Retrieval of Cloud Information using Neural Networks). OCRA retrieves the cloud fraction using TROPOMI measurements in the ultraviolet (UV) and visible (VIS) spectral regions, and ROCINN retrieves the cloud top height (pressure) and optical thickness (albedo) using TROPOMI measurements in and around the oxygen A-band in the near infrared (NIR). Cloud parameters from TROPOMI/S5P will be used not only for enhancing the accuracy of trace gas retrievals but also for extending the satellite data record of cloud information derived from oxygen A-band measurements, a record initiated with the Global Ozone Monitoring Experiment (GOME) on board the second European Remote-Sensing Satellite (ERS-2) over 20 years ago. The OCRA and ROCINN algorithms are integrated in the S5P operational processor UPAS (Universal Processor for UV/VIS/NIR Atmospheric Spectrometers), and we present here UPAS cloud results using the Ozone Monitoring Instrument (OMI) and GOME-2 measurements. In addition, we examine anticipated challenges for the TROPOMI/S5P cloud retrieval algorithms, and we discuss the future validation needs for OCRA and ROCINN.

Aerosol-radiation-cloud interactions in the South-East Atlantic: first results from the ORACLES-2016 deployment and plans for future activities

NASA Astrophysics Data System (ADS)

Redemann, J.; Wood, R.; Zuidema, P.; Haywood, J. M.; Piketh, S.; Formenti, P.; Abel, S.

2016-12-01

Southern Africa produces almost a third of the Earth's biomass burning (BB) aerosol particles. Particles lofted into the mid-troposphere are transported westward over the South-East (SE) Atlantic, home to one of the three permanent subtropical stratocumulus (Sc) cloud decks in the world. The SE Atlantic stratocumulus deck interacts with the dense layers of BB aerosols that initially overlay the cloud deck, but later subside and may mix into the clouds. These interactions include adjustments to aerosol-induced solar heating and microphysical effects, and their global representation in climate models remains one of the largest uncertainties in estimates of future climate. Hence, new observations over the SE Atlantic have significant implications for regional and global climate change predictions. Our understanding of aerosol-cloud interactions in the SE Atlantic is severely limited. Most notably, we are missing knowledge on the absorptive and cloud nucleating properties of aerosols, including their vertical distribution relative to clouds, on the locations and degree of aerosol mixing into clouds, on the processes that govern cloud property adjustments, and on the importance of aerosol effects on clouds relative to co-varying synoptic scale meteorology. We describe first results from various synergistic, international research activities aimed at studying aerosol-cloud interactions in the region: NASA's airborne ORACLES (ObseRvations of Aerosols Above Clouds and Their IntEractionS) deployment in August/September of 2016, the DoE's LASIC (Layered Atlantic Smoke Interactions with Clouds) deployment of the ARM Mobile Facility to Ascension Island (June 2016 - October 2017), the ground-based components of CNRS' AEROCLO-sA (Aerosols Clouds and Fog over the west coast of southern Africa), and ongoing regional-scale integrative, process-oriented science efforts as part of SEALS-sA (Sea Earth Atmosphere Linkages Study in southern Africa). We expect to describe experimental setups as well as showcase initial aerosol and cloud property distributions. Furthermore, we discuss the implementation of future activities in these programs in coordination with the UK Met Office's CLARIFY (CLoud-Aerosol-Radiation Interactions and Forcing) experiment in 2017.

Applications for Near-Real Time Satellite Cloud and Radiation Products

NASA Technical Reports Server (NTRS)

Minnis, Patrick; Palikonda, Rabindra; Chee, Thad L.; Bedka, Kristopher M.; Smith, W.; Ayers, Jeffrey K.; Benjamin, Stanley; Chang, F.-L.; Nguyen, Louis; Norris, Peter;

Improvements on the relationship between plume height and mass eruption rate: Implications for volcanic ash cloud forecasting

NASA Astrophysics Data System (ADS)

Webley, P. W.; Dehn, J.; Mastin, L. G.; Steensen, T. S.

2011-12-01

Volcanic ash plumes and the dispersing clouds into the atmosphere are a hazard for local populations as well as for the aviation industry. Volcanic ash transport and dispersion (VATD) models, used to forecast the movement of these hazardous ash emissions, require eruption source parameters (ESP) such as plume height, eruption rate and duration. To estimate mass eruption rate, empirical relationships with observed plume height have been applied. Theoretical relationships defined by Morton et al. (1956) and Wilson et al. (1976) use default values for the environmental lapse rate (ELR), thermal efficiency, density of ash, specific heat capacity, initial temperature of the erupted material and final temperature of the material. Each volcano, based on its magma type, has a different density, specific heat capacity and initial eruptive temperature compared to these default parameters, and local atmospheric conditions can produce a very different ELR. Our research shows that a relationship between plume height and mass eruption rate can be defined for each eruptive event for each volcano. Additionally, using the one-dimensional modeling program, Plumeria, our analysis assesses the importance of factors such as vent diameter and eruption velocity on the relationship between the eruption rate and measured plume height. Coupling such a tool with a VATD model should improve pre-eruptive forecasts of ash emissions downwind and lead to improvements in ESP data that VATD models use for operational volcanic ash cloud forecasting.

Biological ice nucleation initiates hailstone formation

NASA Astrophysics Data System (ADS)

Michaud, Alexander B.; Dore, John E.; Leslie, Deborah; Lyons, W. Berry; Sands, David C.; Priscu, John C.

2014-11-01

Cloud condensation and ice nuclei in the troposphere are required precursors to cloud and precipitation formation, both of which influence the radiative balance of Earth. The initial stage of hailstone formation (i.e., the embryo) and the subsequent layered growth allow hail to be used as a model for the study of nucleation processes in precipitation. By virtue of the preserved particle and isotopic record captured by hailstones, they represent a unique form of precipitation that allows direct characterization of the particles present during atmospheric ice nucleation. Despite the ecological and economic consequences of hail storms, the dynamics of hailstone nucleation, and thus their formation, are not well understood. Our experiments show that hailstone embryos from three Rocky Mountain storms contained biological ice nuclei capable of freezing water at warm, subzero (°C) temperatures, indicating that biological particles can act as nucleation sites for hailstone formation. These results are corroborated by analysis of δD and δ18O from melted hailstone embryos, which show that the hailstones formed at similarly warm temperatures in situ. Low densities of ice nucleation active abiotic particles were also present in hailstone embryos, but their low concentration indicates they were not likely to have catalyzed ice formation at the warm temperatures determined from water stable isotope analysis. Our study provides new data on ice nucleation occurring at the bottom of clouds, an atmospheric region whose processes are critical to global climate models but which has challenged instrument-based measurements.

Using polarimetry to retrieve the cloud coverage of Earth-like exoplanets

NASA Astrophysics Data System (ADS)

Rossi, L.; Stam, D. M.

2017-11-01

Context. Clouds have already been detected in exoplanetary atmospheres. They play crucial roles in a planet's atmosphere and climate and can also create ambiguities in the determination of atmospheric parameters such as trace gas mixing ratios. Knowledge of cloud properties is required when assessing the habitability of a planet. Aims: We aim to show that various types of cloud cover such as polar cusps, subsolar clouds, and patchy clouds on Earth-like exoplanets can be distinguished from each other using the polarization and flux of light that is reflected by the planet. Methods: We have computed the flux and polarization of reflected starlight for different types of (liquid water) cloud covers on Earth-like model planets using the adding-doubling method, that fully includes multiple scattering and polarization. Variations in cloud-top altitudes and planet-wide cloud cover percentages were taken into account. Results: We find that the different types of cloud cover (polar cusps, subsolar clouds, and patchy clouds) can be distinguished from each other and that the percentage of cloud cover can be estimated within 10%. Conclusions: Using our proposed observational strategy, one should be able to determine basic orbital parameters of a planet such as orbital inclination and estimate cloud coverage with reduced ambiguities from the planet's polarization signals along its orbit.

Properties of dust and clouds in the Mars atmosphere: Analysis of Viking IRTM emission phase function sequences

NASA Technical Reports Server (NTRS)

Clancy, R. T.; Lee, S. W.

1991-01-01

An analysis of emission-phase-function (EPF) observations from the Viking Orbiter Infrared Thermal Mapper (IRTM) yields a wide variety of results regarding dust and cloud scattering in the Mars atmosphere and atmospheric-corrected albedos for the surface of Mars. A multiple scattering radiative transfer model incorporating a bidirectional phase function for the surface and atmospheric scattering by dust and clouds is used to derive surface albedos and dust and ice optical properties and optical depths for these various conditions on Mars.

Experimental evidence for millisecond activation timescales using the Fast IN Chamber (FINCH) measurements

NASA Astrophysics Data System (ADS)

Bundke, U.; Jaenicke, R.; Klein, H.; Nillius, B.; Reimann, B.; Wetter, T.; Bingemer, H.

2009-04-01

Ice formation in clouds is a subject of great practical and fundamental importance since the occurrence of ice particle initializes dramatic changes in the microphysical structure of the cloud, which finally ends in the formation of precipitation. The initially step of ice formation is largely unknown. Homogenous nucleation of ice occurs only below -40 °C. If an ice nucleus (IN) is present, heterogeneous nucleation may occur at higher temperature. Here deposition freezing, condensation and immersion freezing as well as contact freezing are known. Also growth rates of ice particles are known as function of crystal surface properties, temperature and super saturation. Timescales for homogenous freezing activation in the order of 0.01 seconds and nucleation rates have been measured by Anderson et al. (1980) and Hagen et al., (1981) using their expansion cloud chamber. This contribution of deposition mode freezing measurements by the ice nucleus counter FINCH presents evidence that the activation timescale of this freezing mode is in the order of 1E-3 seconds. FINCH is an Ice Nucleus counter which activates IN in a supersaturated environment at freezing temperatures. The activation conditions are actively controlled by mixing three gas flows (aerosol, particle-free cold-dry and warm-humid flows).See Bundke et al. 2008 for details. In a special operation mode of FINCH we are able to produce a controlled peak super saturation in the order of 1 ms duration. For several test aerosols the results observed in this particular mode are comparable to normal mode operations, where the maximum super saturation remains for more than a second, thus leading to the conclusion that the time for activation is in the order of 1ms or less. References: R.J. Anderson et al, "A Study of Homogeneous Condensation Freezing Nucleation of Small Water Droplets in an Expansion Cloud Chamber, Journal of the Atmospheric Sciences, Vol. 37, 2508-2520, 1980 U.Bundke et al., "The fast Ice Nucleus chamber FINCH", Atmospheric Research, Volume 90, Issues 2-4, 180-186, DOI:10.1016/j.atmosres.2008.02.008, 2008 D.E. Hagen et al., "Homogenous Condensation Freezing Nucleation Rate Measurements for Small Water Droplets in an Expansion Cloud Chamber", Journal of the Atmospheric Sciences, Vol 38, 1236-1243, 1981 Acknowledgments: This work was supported by the German Research Foundation: SFB 641 "Tropospheric Ice Phase" TP A1, SPP1294 BU1432/3-1, JA344/12-1, by the Helmholtz Association: VI-233 "Aerosol Cloud Interactions" and by and by the EU FP6 Infastructure Project EUSAAR.

Exploring clouds, weather, climate, and modeling using bilingual content and activities from the Windows to the Universe program and the Center for Multiscale Modeling of Atmospheric Processes

NASA Astrophysics Data System (ADS)

Foster, S. Q.; Johnson, R. M.; Randall, D.; Denning, S.; Russell, R.; Gardiner, L.; Hatheway, B.; Genyuk, J.; Bergman, J.

2008-12-01

The need for improving the representation of cloud processes in climate models has been one of the most important limitations of the reliability of climate-change simulations. Now in its third year, the National Science Foundation-funded Center for Multi-scale Modeling of Atmospheric Processes (CMMAP) at Colorado State University is addressing this problem through a revolutionary new approach to representing cloud processes on their native scales, including the cloud-scale interaction processes that are active in cloud systems. CMMAP has set ambitious education and human-resource goals to share basic information about the atmosphere, clouds, weather, climate, and modeling with diverse K-12 and public audiences through its affiliation with the Windows to the Universe (W2U) program at University Corporation for Atmospheric Research (UCAR). W2U web pages are written at three levels in English and Spanish. This information targets learners at all levels, educators, and families who seek to understand and share resources and information about the nature of weather and the climate system, and career role models from related research fields. This resource can also be helpful to educators who are building bridges in the classroom between the sciences, the arts, and literacy. Visitors to the W2U's CMMAP web portal can access a beautiful new clouds image gallery; information about each cloud type and the atmospheric processes that produce them; a Clouds in Art interactive; collections of weather-themed poetry, art, and myths; links to games and puzzles for children; and extensive classroom- ready resources and activities for K-12 teachers. Biographies of CMMAP scientists and graduate students are featured. Basic science concepts important to understanding the atmosphere, such as condensation, atmosphere pressure, lapse rate, and more have been developed, as well as 'microworlds' that enable students to interact with experimental tools while building fundamental knowledge. These resources can be accessed online at no cost by the entire atmospheric science K-12 and informal science education community.

Radiative Impacts of Cloud Heterogeneity and Overlap in an Atmospheric General Circulation Model

NASA Technical Reports Server (NTRS)

Oreopoulos, L.; Lee, D.; Sud, Y. C.; Suarez, M. J.

2012-01-01

The radiative impacts of introducing horizontal heterogeneity of layer cloud condensate, and vertical overlap of condensate and cloud fraction are examined with the aid of a new radiation package operating in the GEOS-5 Atmospheric General Circulation Model. The impacts are examined in terms of diagnostic top-of-the-atmosphere shortwave (SW) and longwave (LW) cloud radiative effect (CRE) calculations for a range of assumptions and parameter specifications about the overlap. The investigation is conducted for two distinct cloud schemes, the one that comes with the standard GEOS-5 distribution, and another which has been recently used experimentally for its enhanced GEOS-5 distribution, and another which has been recently used experimentally for its enhanced cloud microphysical capabilities; both are coupled to a cloud generator allowing arbitrary cloud overlap specification. We find that cloud overlap radiative impacts are significantly stronger for the operational cloud scheme for which a change of cloud fraction overlap from maximum-random to generalized results to global changes of SW and LW CRE of approximately 4 Watts per square meter, and zonal changes of up to approximately 10 Watts per square meter. This is because of fewer occurrences compared to the other scheme of large layer cloud fractions and of multi-layer situations with large numbers of atmospheric being simultaneously cloudy, conditions that make overlap details more important. The impact on CRE of the details of condensate distribution overlap is much weaker. Once generalized overlap is adopted, both cloud schemes are only modestly sensitive to the exact values of the overlap parameters. We also find that if one of the CRE components is overestimated and the other underestimated, both cannot be driven towards observed values by adjustments to cloud condensate heterogeneity and overlap alone.

A multilinear regression methodology to analyze the effect of atmospheric and surface forcing on Arctic clouds

NASA Astrophysics Data System (ADS)

Boeke, R.; Taylor, P. C.; Li, Y.

2017-12-01

Arctic cloud amount as simulated in CMIP5 models displays large intermodel spread- models disagree on the processes important for cloud formation as well as the radiative impact of clouds. The radiative response to cloud forcing can be better assessed when the drivers of Arctic cloud formation are known. Arctic cloud amount (CA) is a function of both atmospheric and surface conditions, and it is crucial to separate the influences of unique processes to understand why the models are different. This study uses a multilinear regression methodology to determine cloud changes using 3 variables as predictors: lower tropospheric stability (LTS), 500-hPa vertical velocity (ω500), and sea ice concentration (SIC). These three explanatory variables were chosen because their effects on clouds can be attributed to unique climate processes: LTS is a thermodynamic indicator of the relationship between clouds and atmospheric stability, SIC determines the interaction between clouds and the surface, and ω500 is a metric for dynamical change. Vertical, seasonal profiles of necessary variables are obtained from the Coupled Model Intercomparison Project 5 (CMIP5) historical simulation, an ocean-atmosphere couple model forced with the best-estimate natural and anthropogenic radiative forcing from 1850-2005, and statistical significance tests are used to confirm the regression equation. A unique heuristic model will be constructed for each climate model and for observations, and models will be tested by their ability to capture the observed cloud amount and behavior. Lastly, the intermodel spread in Arctic cloud amount will be attributed to individual processes, ranking the relative contributions of each factor to shed light on emergent constraints in the Arctic cloud radiative effect.

Fate of Ice Grains in Saturn's Ionosphere

NASA Astrophysics Data System (ADS)

Hamil, O.; Cravens, T. E.; Reedy, N. L.; Sakai, S.

2018-02-01

It has been proposed that the rings of Saturn can contribute both material (i.e., water) and energy to its upper atmosphere and ionosphere. Ionospheric models require the presence of molecular species such as water that can chemically remove ionospheric protons, which otherwise are associated with electron densities that greatly exceed those from observation. These models adopt topside fluxes of water molecules. Other models have shown that ice grains from Saturn's rings can impact the atmosphere, but the effects of these grains have not been previously studied. In the current paper, we model how ice grains deposit both material and energy in Saturn's upper atmosphere as a function of grain size, initial velocity (at the "top" of the atmosphere, defined at an altitude above the cloud tops of 3,000 km), and incident angle. Typical grain speeds are expected to be roughly 15-25 km/s. Grains with radii on the order of 1-10 nm deposit most of their energy in the altitude range of 1,700-1,900 km, and can vaporize, depending on initial velocity and impact angle, contributing water mass to the upper atmosphere. We show that grains in this radius range do not significantly vaporize in our model at initial velocities lower than about 20 km/s.

Trapping of water vapor from an atmosphere by condensed silicate matter formed by high-temperature pulse vaporization

NASA Technical Reports Server (NTRS)

Gerasimov, M. V.; Dikov, Yu. P.; Yakovlev, O. I.; Wlotzka, F.

1993-01-01

The origin of planetary atmospheres is thought to be the result of bombardment of a growing planet by massive planetesimals. According to some models, the accumulation of released water vapor and/or carbon dioxide can result in the formation of a dense and hot primordial atmosphere. Among source and sink processes of atmospheric water vapor the formation of hydroxides was considered mainly as rehydration of dehydrated minerals (foresterite and enstatite). From our point of view, the formation of hydroxides is not limited to rehydration. Condensation of small silicate particles in a spreading vapor cloud and their interaction with a wet atmosphere can also result in the origin of hydrated phases which have no genetic connections with initial water bearing minerals. We present results of two experiments of a simulated interaction of condensed silicate matter which originated during vaporization of dry clinopyroxene in a wet helium atmosphere.

GEWEX cloud assessment: A review

NASA Astrophysics Data System (ADS)

Stubenrauch, Claudia; Rossow, William B.; Kinne, Stefan; Ackerman, Steve; Cesana, Gregory; Chepfer, Hélène; Di Girolamo, Larry; Getzewich, Brian; Guignard, Anthony; Heidinger, Andy; Maddux, Brent; Menzel, Paul; Minnis, Patrick; Pearl, Cindy; Platnick, Steven; Poulsen, Caroline; Riedi, Jérôme; Sayer, Andrew; Sun-Mack, Sunny; Walther, Andi; Winker, Dave; Zeng, Shen; Zhao, Guangyu

2013-05-01

Clouds cover about 70% of the Earth's surface and play a dominant role in the energy and water cycle of our planet. Only satellite observations provide a continuous survey of the state of the atmosphere over the entire globe and across the wide range of spatial and temporal scales that comprise weather and climate variability. Satellite cloud data records now exceed more than 25 years; however, climatologies compiled from different satellite datasets can exhibit systematic biases. Questions therefore arise as to the accuracy and limitations of the various sensors. The Global Energy and Water cycle Experiment (GEWEX) Cloud Assessment, initiated in 2005 by the GEWEX Radiation Panel, provides the first coordinated intercomparison of publicly available, global cloud products (gridded, monthly statistics) retrieved from measurements of multi-spectral imagers (some with multi-angle view and polarization capabilities), IR sounders and lidar. Cloud properties under study include cloud amount, cloud height (in terms of pressure, temperature or altitude), cloud radiative properties (optical depth or emissivity), cloud thermodynamic phase and bulk microphysical properties (effective particle size and water path). Differences in average cloud properties, especially in the amount of high-level clouds, are mostly explained by the inherent instrument measurement capability for detecting and/or identifying optically thin cirrus, especially when overlying low-level clouds. The study of long-term variations with these datasets requires consideration of many factors. The monthly, gridded database presented here facilitates further assessments, climate studies, and the evaluation of climate models.

Hubble Provides Infrared View of Jupiter's Moon, Ring, and Clouds

NASA Technical Reports Server (NTRS)

1997-01-01

Probing Jupiter's atmosphere for the first time, the Hubble Space Telescope's new Near Infrared Camera and Multi-Object Spectrometer (NICMOS) provides a sharp glimpse of the planet's ring, moon, and high-altitude clouds.

The presence of methane in Jupiter's hydrogen- and helium-rich atmosphere has allowed NICMOS to plumb Jupiter's atmosphere, revealing bands of high-altitude clouds. Visible light observations cannot provide a clear view of these high clouds because the underlying clouds reflect so much visible light that the higher level clouds are indistinguishable from the lower layer. The methane gas between the main cloud deck and the high clouds absorbs the reflected infrared light, allowing those clouds that are above most of the atmosphere to appear bright. Scientists will use NICMOS to study the high altitude portion of Jupiter's atmosphere to study clouds at lower levels. They will then analyze those images along with visible light information to compile a clearer picture of the planet's weather. Clouds at different levels tell unique stories. On Earth, for example, ice crystal (cirrus) clouds are found at high altitudes while water (cumulus) clouds are at lower levels.

Besides showing details of the planet's high-altitude clouds, NICMOS also provides a clear view of the ring and the moon, Metis. Jupiter's ring plane, seen nearly edge-on, is visible as a faint line on the upper right portion of the NICMOS image. Metis can be seen in the ring plane (the bright circle on the ring's outer edge). The moon is 25 miles wide and about 80,000 miles from Jupiter.

Because of the near-infrared camera's narrow field of view, this image is a mosaic constructed from three individual images taken Sept. 17, 1997. The color intensity was adjusted to accentuate the high-altitude clouds. The dark circle on the disk of Jupiter (center of image) is an artifact of the imaging system.

This image and other images and data received from the Hubble Space Telescope are posted on the World Wide Web on the Space Telescope Science Institute home page at URL http://oposite.stsci.edu/pubinfo/

New framework for extending cloud chemistry in the Community Multiscale Air Quality (CMAQ) modeling

EPA Science Inventory

Clouds and fogs significantly impact the amount, composition, and spatial distribution of gas and particulate atmospheric species, not least of which through the chemistry that occurs in cloud droplets. Atmospheric sulfate is an important component of fine aerosol mass and in an...

Mass spectrometric determination of the composition of the Venus clouds

NASA Technical Reports Server (NTRS)

Herzog, R. F. K.

1973-01-01

The instrumentation is analyzed for determining the composition of the clouds on Venus. Direct analysis of the gas phase atmosphere, and the detection of ferrous chloride with a mass spectrometer are dicussed along with the mass analyzer, and the pre-separation of cloud particles from the ambient atmosphere.

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

NASA Technical Reports Server (NTRS)

Taylor, Patrick C.

2015-01-01

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

Assessing impacts of PBL and surface layer schemes in simulating the surface–atmosphere interactions and precipitation over the tropical ocean using observations from AMIE/DYNAMO

DOE PAGES

Qian, Yun; Yan, Huiping; Berg, Larry K.; ...

2016-10-28

Accuracy of turbulence parameterization in representing Planetary Boundary Layer (PBL) processes in climate models is critical for predicting the initiation and development of clouds, air quality issues, and underlying surface-atmosphere-cloud interactions. In this study, we 1) evaluate WRF model-simulated spatial patterns of precipitation and surface fluxes, as well as vertical profiles of potential temperature, humidity, moist static energy and moisture tendency terms as simulated by WRF at various spatial resolutions and with PBL, surface layer and shallow convection schemes against measurements, 2) identify model biases by examining the moisture tendency terms contributed by PBL and convection processes through nudging experiments,more » and 3) evaluate the dependence of modeled surface latent heat (LH) fluxes onPBL and surface layer schemes over the tropical ocean. The results show that PBL and surface parameterizations have surprisingly large impacts on precipitation, convection initiation and surface moisture fluxes over tropical oceans. All of the parameterizations tested tend to overpredict moisture in PBL and free atmosphere, and consequently result in larger moist static energy and precipitation. Moisture nudging tends to suppress the initiation of convection and reduces the excess precipitation. The reduction in precipitation bias in turn reduces the surface wind and LH flux biases, which suggests that the model drifts at least partly because of a positive feedback between precipitation and surface fluxes. The updated shallow convection scheme KF-CuP tends to suppress the initiation and development of deep convection, consequently decreasing precipitation. The Eta surface layer scheme predicts more reasonable LH fluxes and the LH-Wind Speed relationship than the MM5 scheme, especially when coupled with the MYJ scheme. By examining various parameterization schemes in WRF, we identify sources of biases and weaknesses of current PBL, surface layer and shallow convection schemes in reproducing PBL processes, the initiation of convection and intra-seasonal variability of precipitation.« less

The Thermal Emission and Albedo of Super-Earths with Flat Transmission Spectra

NASA Astrophysics Data System (ADS)

Morley, Caroline; Fortney, Jonathan; Marley, Mark

2014-11-01

Vast resources have been dedicated to characterizing the handful of planets with radii between Earth’s and Neptune’s that are accessible to current telescopes. Observations of their transmission spectra have been inconclusive and do not constrain the atmospheric composition. Here, we present a path forward for understanding this class of small planets: by understanding the thermal emission and reflectivity of small planets, we can break these degeneracies and constrain the atmospheric composition. Of the ~four small planets studied to date, all have radii in the near-IR consistent with being constant in wavelength. This suggests either that these planets all have higher mean molecular weight atmospheres than expected for hydrogen-dominated bulk compositions, or that the atmospheres of small planets are consistently enshrouded in thick hazes and clouds. For the particularly well-studied planet GJ 1214b, the measurements made using HST/WFC3 can rule out atmospheres with high mean molecular weights, leaving clouds as the sole explanation for the flat transmission spectrum. We showed in Morley et al. 2013 that these clouds and hazes can be made of salts and sulfides, which condense in the upper atmosphere of a cool H-rich atmosphere like GJ 1214b, or made of photochemical hazes such as soots, which result from methane photodissociation and subsequent carbon chemistry. Here, we explore how clouds thick enough to obscure the transmission spectrum change both thermal emission spectra and albedo spectra. These observations are complementary to transmission spectra measurements. Thermal emission probes deeper layers of the atmosphere, potentially below the high haze layer obscuring the transmission spectra; albedo spectra probe reflected starlight largely from the cloud particles themselves. Crucially, these complementary observations of planets with flat transmission spectra may allow us to break the degeneracies between cloud materials, cloud height and longitude, and bulk composition of the atmosphere. We make predictions for the observability of known planets for current and future telescopes.

The Thermal Emission and Albedo of Super-Earths with Flat Transmission Spectra

NASA Astrophysics Data System (ADS)

Morley, Caroline; Fortney, Jonathan J.; Marley, Mark

2015-01-01

Vast resources have been dedicated to characterizing the handful of planets with radii between Earth's and Neptune's that are accessible to current telescopes. Observations of their transmission spectra have been inconclusive and do not constrain the atmospheric composition. Here, we present a path forward for understanding this class of small planets: by understanding the thermal emission and reflectivity of small planets, we can break these degeneracies and constrain the atmospheric composition.Of the ~five small planets studied to date, four have radii in the near-IR consistent with being constant in wavelength. This suggests either that these planets all have higher mean molecular weight atmospheres than expected for hydrogen-dominated bulk compositions, or that the atmospheres of small planets are consistently enshrouded in thick hazes and clouds. For the particularly well-studied planet GJ 1214b, the measurements made using HST/WFC3 can rule out atmospheres with high mean molecular weights, leaving clouds as the sole explanation for the flat transmission spectrum. We showed in Morley et al. 2013 that these clouds and hazes can be made of salts and sulfides, which condense in the upper atmosphere of a cool H-rich atmosphere like GJ 1214b, or made of photochemical hazes such as soots, which result from methane photodissociation and subsequent carbon chemistry. Here, we explore how clouds thick enough to obscure the transmission spectrum change both thermal emission spectra and albedo spectra. These observations are complementary to transmission spectra measurements. Thermal emission probes deeper layers of the atmosphere, potentially below the high haze layer obscuring the transmission spectra; albedo spectra probe reflected starlight largely from the cloud particles themselves. Crucially, these complementary observations of planets with flat transmission spectra may allow us to break the degeneracies between cloud materials, cloud height and longitude, and bulk composition of the atmosphere. We make predictions for the observability of known planets for current and future telescopes.

Coupling of Clouds and Moisture Transport in Extratropical Cyclonic Systems and the Associated Atmospheric Heating (Q1) and Moisture Sink (Q2)

NASA Astrophysics Data System (ADS)

Wong, S.; Naud, C. M.; Kahn, B. H.; Wu, L.; Fetzer, E. J.

2017-12-01

Different sectors in extratropical cyclonic systems (ETCs) exhibit various patterns in atmospheric moisture transport and provide an excellent test bed for studying coupling between cloud processes and large-scale circulation. Large-scale atmospheric moisture transport diagnosed from the Modern-Era Retrospective analysis for Research and Applications Version 2 and cloud properties (cloud top pressure and optical depth, cloud 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 clouds with middle-to-upper tropospheric heating and lower tropospheric cooling, while upright convection in the warm front regime has frequent deep convective clouds with free-tropospheric heating and strong boundary layer cooling. Thinner stratiform and cirrus clouds 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 layers of the cold sector, polar-air intrusion, and pre-warm sector regimes depends on the amount of low-level clouds, which is again modulated by the stage of the ETC development.

ARC-1990-A91-2001

NASA Image and Video Library

1990-02-19

Range : 60,000 miles These images are two versions of a near-infrafed map of lower-level clouds on the night side of Venus, obtained by the Near Infrared Mapping Spectrometer aboard the Galileo spacecraft.The map shows the turbulent, cloudy middle 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 F) ahining 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 170 degrees F, 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 slsivers of daylit high clouds 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 cloud deck in daylight, with the clouds reflecting sunlight instead of clocking out infrared from the hot planet and lower atmosphere. Near the equator, the clouds appear fluffy and clocky; 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. The Near Infrared Mapping Spectrometer (NIMS) on the Galileo 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 spectroscopic-ally analyze atmospheres and surfaces and construct thermal and chemical maps.

ARC-1990-A91-2002

NASA Image and Video Library

1990-02-10

Range : 60,000 miles These images are two versions of a near-infrafed map of lower-level clouds on the night side of Venus, obtained by the Near Infrared Mapping Spectrometer aboard the Galileo spacecraft.The map shows the turbulent, cloudy middle 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 F) ahining 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 170 degrees F, 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 slsivers of daylit high clouds 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 cloud deck in daylight, with the clouds reflecting sunlight instead of clocking out infrared from the hot planet and lower atmosphere. Near the equator, the clouds appear fluffy and clocky; 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. The Near Infrared Mapping Spectrometer (NIMS) on the Galileo 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 spectroscopic-ally analyze atmospheres and surfaces and construct thermal and chemical maps.

The Goddard Cumulus Ensemble Model (GCE): Improvements and Applications for Studying Precipitation Processes

NASA Technical Reports Server (NTRS)

Tao, Wei-Kuo; Lang, Stephen E.; Zeng, Xiping; Li, Xiaowen; Matsui, Toshi; Mohr, Karen; Posselt, Derek; Chern, Jiundar; Peters-Lidard, Christa; Norris, Peter M.;

The East and Southeast Asia Initiatives: Aerosol Column Measurements

NASA Technical Reports Server (NTRS)

Tsay, Si-Chee; Hsu, Christina N.; Li, Zhanqing

2003-01-01

Airborne dusts from northern China contribute a significant part of the air quality problem and, to some extent, regional climatic impact in Asia during spring- time. However, with the economical growth in China, increases in the emission of air pollutants generated from industrial and vehicular sources will not only impact the radiation balance, but adverse health effects to humans all year round. In addition, both of these dust and air pollution clouds can transport swiftly across the Pacific reaching North America within a few days, possessing an even larger scale effect. The Asian dust and air pollution aerosols can be detected by its colored appearance on current Earth observing satellites (e.g., MODIS, SeaWiFS, TOMS, etc.) and its evolution monitored by satellites and surface network. Biomass burning has been a regular practice for land clearing and land conversion in many countries, especially those in Africa, South America, and Southeast Asia. However, the unique climatology of Southeast Asia is very different than that of Africa and South America, such that large-scale biomass burning causes smoke to interact extensively with clouds during the peak-burning season of March to April. Significant global sources of greenhouse gases (e.g., CO2, CH4), chemically active gases (e.g., NO, CO, HC, CH3,Br), and atmospheric aerosols are produced by biomass burning processes. These gases influence the Earth- atmosphere system, impacting both global climate and tropospheric chemistry. Some aerosols can serve as cloud condensation nuclei, which play an important role in determining cloud lifetime and precipitation, hence, altering the earth's radiation and water budget. Biomass burning also affects the biogeochemical cycling of nitrogen and carbon compounds from the soil to the atmosphere; the hydrological cycle (i.e., run off and evaporation); land surface reflectivity and emissivity; as well as ecosystem biodiversity and stability. Two new initiatives, EAST-AIRE (East Asian Study of Tropospheric Aerosols: an International Regional Experiment) and BASE-ASIA (Biomass-burning Aerosols in South East-Asia: Smoke Impact Assessment) will be presented and discussed their contribution to better understand the impacts of aerosols on regional-to- global climate, hydrological and carbon cycles, and tropospheric chemistry.

A CERES-like Cloud Property Climatology Using AVHRR Data

NASA Astrophysics Data System (ADS)

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

2015-12-01

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

Global Simulations of Ice nucleation and Ice Supersaturation with an Improved Cloud Scheme in the Community Atmosphere Model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gettelman, A.; Liu, Xiaohong; Ghan, Steven J.

2010-09-28

A process-based treatment of ice supersaturation and ice-nucleation is implemented in the National Center for Atmospheric Research (NCAR) Community Atmosphere Model (CAM). The new scheme is designed to allow (1) supersaturation with respect to ice, (2) ice nucleation by aerosol particles and (3) ice cloud cover consistent with ice microphysics. The scheme is implemented with a 4-class 2 moment microphysics code and is used to evaluate ice cloud nucleation mechanisms and supersaturation in CAM. The new model is able to reproduce field observations of ice mass and mixed phase cloud occurrence better than previous versions of the model. Simulations indicatemore » heterogeneous freezing and contact nucleation on dust are both potentially important over remote areas of the Arctic. Cloud forcing and hence climate is sensitive to different formulations of the ice microphysics. Arctic radiative fluxes are sensitive to the parameterization of ice clouds. These results indicate that ice clouds are potentially an important part of understanding cloud forcing and potential cloud feedbacks, particularly in the Arctic.« less

Remote sensing of smoke, clouds, and fire using AVIRIS data

NASA Technical Reports Server (NTRS)

Gao, Bo-Cai; Kaufman, Yorman J.; Green, Robert O.

1993-01-01

Clouds remain the greatest element of uncertainty in predicting global climate change. During deforestation and biomass burning processes, a variety of atmospheric gases, including CO2 and SO2, and smoke particles are released into the atmosphere. The smoke particles can have important effects on the formation of clouds because of the increased concentration of cloud condensation nuclei. They can also affect cloud albedo through changes in cloud microphysical properties. Recently, great interest has arisen in understanding the interaction between smoke particles and clouds. We describe our studies of smoke, clouds, and fire using the high spatial and spectral resolution data acquired with the NASA/JPL Airborne Visible/Infrared Imaging Spectrometer (AVIRIS).

Assessing 1D Atmospheric Solar Radiative Transfer Models: Interpretation and Handling of Unresolved Clouds.

NASA Astrophysics Data System (ADS)

Barker, H. W.; Stephens, G. L.; Partain, P. T.; Bergman, J. W.; Bonnel, B.; Campana, K.; Clothiaux, E. E.; Clough, S.; Cusack, S.; Delamere, J.; Edwards, J.; Evans, K. F.; Fouquart, Y.; Freidenreich, S.; Galin, V.; Hou, Y.; Kato, S.; Li, J.;  Mlawer, E.;  Morcrette, J.-J.;  O'Hirok, W.;  Räisänen, P.;  Ramaswamy, V.;  Ritter, B.;  Rozanov, E.;  Schlesinger, M.;  Shibata, K.;  Sporyshev, P.;  Sun, Z.;  Wendisch, M.;  Wood, N.;  Yang, F.

2003-08-01

The primary purpose of this study is to assess the performance of 1D solar radiative transfer codes that are used currently both for research and in weather and climate models. Emphasis is on interpretation and handling of unresolved clouds. Answers are sought to the following questions: (i) How well do 1D solar codes interpret and handle columns of information pertaining to partly cloudy atmospheres? (ii) Regardless of the adequacy of their assumptions about unresolved clouds, do 1D solar codes perform as intended?One clear-sky and two plane-parallel, homogeneous (PPH) overcast cloud cases serve to elucidate 1D model differences due to varying treatments of gaseous transmittances, cloud optical properties, and basic radiative transfer. The remaining four cases involve 3D distributions of cloud water and water vapor as simulated by cloud-resolving models. Results for 25 1D codes, which included two line-by-line (LBL) models (clear and overcast only) and four 3D Monte Carlo (MC) photon transport algorithms, were submitted by 22 groups. Benchmark, domain-averaged irradiance profiles were computed by the MC codes. For the clear and overcast cases, all MC estimates of top-of-atmosphere albedo, atmospheric absorptance, and surface absorptance agree with one of the LBL codes to within ±2%. Most 1D codes underestimate atmospheric absorptance by typically 15-25 W m-2 at overhead sun for the standard tropical atmosphere regardless of clouds.Depending on assumptions about unresolved clouds, the 1D codes were partitioned into four genres: (i) horizontal variability, (ii) exact overlap of PPH clouds, (iii) maximum/random overlap of PPH clouds, and (iv) random overlap of PPH clouds. A single MC code was used to establish conditional benchmarks applicable to each genre, and all MC codes were used to establish the full 3D benchmarks. There is a tendency for 1D codes to cluster near their respective conditional benchmarks, though intragenre variances typically exceed those for the clear and overcast cases. The majority of 1D codes fall into the extreme category of maximum/random overlap of PPH clouds and thus generally disagree with full 3D benchmark values. Given the fairly limited scope of these tests and the inability of any one code to perform extremely well for all cases begs the question that a paradigm shift is due for modeling 1D solar fluxes for cloudy atmospheres.

Satellite-Observed Vertical Structures of Clouds over the Amazon Basin

NASA Astrophysics Data System (ADS)

Wu, M.; Lee, J. E.

2017-12-01

The long wet season of the Amazon basin currently plays a critical role in the terrestrial ecosystem, regulating carbon balance and supporting high biodiversity. It has been argued that the land surface processes are important in maintaining high precipitation; yet, how the land-atmosphere interactions modulate the atmospheric processes are not completely understood. As a first step toward solving this problem, here we examine the vertical structures of clouds and the thermodynamics of the atmosphere over the entire basin at the different time of the year. We combine the vertical distribution of cloud water content from CloudSat, and the atmospheric thermodynamic conditions from the ECMWF ERA-interim reanalysis to compare and contrast the atmospheric condition at different time of the year-the wet, dry, and dry-to-wet transition seasons-and in different regions-ever-wet evergreen broadleaf forests, wet evergreen broadleaf forests with a dry season, and dry wooded grasslands/woodlands-following water stress gradient. In the ever-wet and wet regions, a large amount of cloud ice water is present in the upper atmosphere (above 11km) and convective available potential energy (CAPE) is high during the transition season, supporting the claim that the convective activity is strongest during the transition season. In the dry region, there are more cloud water above 8km over woodlands than over wooded grasslands during the dry and transition seasons, indicating the influence of the land cover. We also classified our data following the large-scale circulation pattern, and the CloudSat data support more deep convective activities in the wet and dry regions when the wind blows from the east during the wet and transition seasons. As a next step, we will focus more on linking the cloud structure to the large-scale circulation and surface processes.

Cloud and aerosol optical depths

NASA Technical Reports Server (NTRS)

Pueschel, R. F.; Russell, P. B.; Ackerman, Thomas P.; Colburn, D. C.; Wrigley, R. C.; Spanner, M. A.; Livingston, J. M.

1988-01-01

An airborne Sun photometer was used to measure optical depths in clear atmospheres between the appearances of broken stratus clouds, and the optical depths in the vicinity of smokes. Results show that (human) activities can alter the chemical and optical properties of background atmospheres to affect their spectral optical depths. Effects of water vapor adsorption on aerosol optical depths are apparent, based on data of the water vapor absorption band centered around 940 nm. Smoke optical depths show increases above the background atmosphere by up to two orders of magnitude. When the total optical depths measured through clouds were corrected for molecular scattering and gaseous absorption by subtracting the total optical depths measured through the background atmosphere, the resultant values are lower than those of the background aerosol at short wavelengths. The spectral dependence of these cloud optical depths is neutral, however, in contrast to that of the background aerosol or the molecular atmosphere.

A Global, Decadal, Quantitative Record of Absorbing Aerosols above Cloud Using OMI's Near-UV Observations

NASA Astrophysics Data System (ADS)

Torres, O.; Jethva, H. T.; Ahn, C.

2016-12-01

Aerosol-cloud interaction continues to be one of the leading uncertain components of climate models, primarily due to the lack of an adequate knowledge of the complex microphysical and radiative processes of the aerosol-cloud system. The situations when aerosols and clouds are found in the same atmospheric column, for instance, when light-absorbing aerosols such as biomass burning generated carbonaceous particles or wind-blown dust overlay low-level cloud decks, are commonly found over several regions of the world. Contrary to the known cooling effects of these aerosols in cloud-free scenario over dark surface, the overlapping situation of absorbing aerosols over cloud can potentially exert a significant level of atmospheric absorption and produces a positive radiative forcing (warming) at top-of-atmosphere. The magnitude of direct radiative effects of aerosols above cloud directly depends on the aerosol loading, microphysical and optical properties of the aerosol layer and the underlying cloud deck, and geometric cloud fraction. We help in addressing this problem by introducing a novel product of above-cloud aerosol optical depth (ACAOD) of absorbing aerosols retrieved from near-UV observations made by the Ozone Monitoring Instrument (OMI) on board NASA's Aura platform. Physically based on the strong `color ratio' effect in the near-UV caused by the spectral absorption of aerosols above cloud, the algorithm, formally named as OMACA, retrieves the optical depths of aerosols and clouds simultaneously under a prescribed state of atmosphere. Here, we present the algorithm architecture and results from an 11-year global record (2005-2015) including global climatology of frequency of occurrence and ACAOD. The theoretical uncertainty analysis and planned validation activities using measurements from upcoming field campaigns are also discussed.

Near-Surface Meteorology During the Arctic Summer Cloud Ocean Study (ASCOS): Evaluation of Reanalyses and Global Climate Models.

NASA Technical Reports Server (NTRS)

De Boer, G.; Shupe, M.D.; Caldwell, P.M.; Bauer, Susanne E.; Persson, O.; Boyle, J.S.; Kelley, M.; Klein, S.A.; Tjernstrom, M.

2014-01-01

Atmospheric measurements from the Arctic Summer Cloud Ocean Study (ASCOS) are used to evaluate the performance of three atmospheric reanalyses (European Centre for Medium Range Weather Forecasting (ECMWF)- Interim reanalysis, National Center for Environmental Prediction (NCEP)-National Center for Atmospheric Research (NCAR) reanalysis, and NCEP-DOE (Department of Energy) reanalysis) and two global climate models (CAM5 (Community Atmosphere Model 5) and NASA GISS (Goddard Institute for Space Studies) ModelE2) in simulation of the high Arctic environment. Quantities analyzed include near surface meteorological variables such as temperature, pressure, humidity and winds, surface-based estimates of cloud and precipitation properties, the surface energy budget, and lower atmospheric temperature structure. In general, the models perform well in simulating large-scale dynamical quantities such as pressure and winds. Near-surface temperature and lower atmospheric stability, along with surface energy budget terms, are not as well represented due largely to errors in simulation of cloud occurrence, phase and altitude. Additionally, a development version of CAM5, which features improved handling of cloud macro physics, has demonstrated to improve simulation of cloud properties and liquid water amount. The ASCOS period additionally provides an excellent example of the benefits gained by evaluating individual budget terms, rather than simply evaluating the net end product, with large compensating errors between individual surface energy budget terms that result in the best net energy budget.

Improved cloud parameterization for Arctic climate simulations based on satellite data

NASA Astrophysics Data System (ADS)

Klaus, Daniel; Dethloff, Klaus; Dorn, Wolfgang; Rinke, Annette

2015-04-01

The defective representation of Arctic cloud processes and properties remains a crucial problem in climate modelling and in reanalysis products. Satellite-based cloud observations (MODIS and CPR/CALIOP) and single-column model simulations (HIRHAM5-SCM) were exploited to evaluate and improve the simulated Arctic cloud cover of the atmospheric regional climate model HIRHAM5. The ECMWF reanalysis dataset 'ERA-Interim' (ERAint) was used for the model initialization, the lateral boundary forcing as well as the dynamical relaxation inside the pan-Arctic domain. HIRHAM5 has a horizontal resolution of 0.25° and uses 40 pressure-based and terrain-following vertical levels. In comparison with the satellite observations, the HIRHAM5 control run (HH5ctrl) systematically overestimates total cloud cover, but to a lesser extent than ERAint. The underestimation of high- and mid-level clouds is strongly outweighed by the overestimation of low-level clouds. Numerous sensitivity studies with HIRHAM5-SCM suggest (1) the parameter tuning, enabling a more efficient Bergeron-Findeisen process, combined with (2) an extension of the prognostic-statistical (PS) cloud scheme, enabling the use of negatively skewed beta distributions. This improved model setup was then used in a corresponding HIRHAM5 sensitivity run (HH5sens). While the simulated high- and mid-level cloud cover is improved only to a limited extent, the large overestimation of low-level clouds can be systematically and significantly reduced, especially over sea ice. Consequently, the multi-year annual mean area average of total cloud cover with respect to sea ice is almost 14% lower than in HH5ctrl. Overall, HH5sens slightly underestimates the observed total cloud cover but shows a halved multi-year annual mean bias of 2.2% relative to CPR/CALIOP at all latitudes north of 60° N. Importantly, HH5sens produces a more realistic ratio between the cloud water and ice content. The considerably improved cloud simulation manifests in a more correct radiative transfer and better energy budget in the atmospheric boundary layer and results also in a more realistic surface energy budget associated with more reasonable turbulent fluxes. All this mitigates the positive temperature, relative humidity and horizontal wind speed biases in the lower model levels.

Submillimeter-Wave Cloud Ice Radiometry

NASA Technical Reports Server (NTRS)

Walter, Steven J.

1999-01-01

Submillimeter-wave cloud ice radiometry is a new and innovative technique for characterizing cirrus ice clouds. Cirrus clouds affect Earth's climate and hydrological cycle by reflecting incoming solar energy, trapping outgoing IR radiation, sublimating into vapor, and influencing atmospheric circulation. Since uncertainties in the global distribution of cloud ice restrict the accuracy of both climate and weather models, successful development of this technique could provide a valuable tool for investigating how clouds affect climate and weather. Cloud ice radiometry could fill an important gap in the observational capabilities of existing and planned Earth-observing systems. Using submillimeter-wave radiometry to retrieve properties of ice clouds can be understood with a simple model. There are a number of submillimeter-wavelength spectral regions where the upper troposphere is transparent. At lower tropospheric altitudes water vapor emits a relatively uniform flux of thermal radiation. When cirrus clouds are present, they scatter a portion of the upwelling flux of submillimeter-wavelength radiation back towards the Earth as shown in the diagram, thus reducing the upward flux o f energy. Hence, the power received by a down-looking radiometer decreases when a cirrus cloud passes through the field of view causing the cirrus cloud to appear radiatively cool against the warm lower atmospheric thermal emissions. The reduction in upwelling thermal flux is a function of both the total cloud ice content and mean crystal size. Radiometric measurements made at multiple widely spaced frequencies permit flux variations caused by changes in crystal size to be distinguished from changes in ice content, and polarized measurements can be used to constrain mean crystal shape. The goal of the cloud ice radiometry program is to further develop and validate this technique of characterizing cirrus. A multi-frequency radiometer is being designed to support airborne science and spacecraft validation missions. This program has already extended the initial millimeter-wave modeling studies to submillimeter-wavelengths and has improved the realism of the cloud scattering models. Additionally a proof-of-concept airborne submillimeter-wave radiometer was constructed and fielded. It measured a radiometric signal from cirrus confirming the basic technical feasibility of this technique. This program is a cooperative effort of the University of Colorado, Colorado State University, Swales Aerospace, and Jet Propulsion Laboratory. Additional information is contained in the original.

Jupiter's Multi-level Clouds

NASA Technical Reports Server (NTRS)

1997-01-01

Clouds 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 cloud 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 clouds down to a level about three times the atmospheric pressure at the Earth's surface.

By contrast, the middle image in top row, taken at 2.17 microns, shows only the highest altitude clouds 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 clouds, 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 clouds can be seen dimly against gaseous ammonia and methane absorption. In the lower middle image, at 4.99 microns, the light observed is the planet's own indigenous heat from the deep, warm atmosphere.

The false color image (lower right) succinctly shows various cloud 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 cloud cover; green denotes cool temperatures of the tropospheric clouds; blue denotes cold of the upper troposphere and lower stratosphere. The polar regions appear purplish, because small-particle hazes allow leakage and reflectivity, while yellowish regions at temperate latitudes may indicate tropospheric clouds with small particles which also allow leakage. A mix of high and low-altitude aerosols causes the aqua appearance of the Great Red Spot and equatorial region.

The Jet Propulsion Laboratory manages the Galileo mission for NASA's Office of Space Science, Washington, DC.

This image and other images and data received from Galileo are posted on the World Wide Web Galileo mission home page at http://galileo.jpl.nasa.gov.

Ice water path estimation and characterization using passive microwave radiometry

NASA Technical Reports Server (NTRS)

Vivekanandan, J.; Turk, J.; Bringi, V. N.

1991-01-01

Model computations of top-of-atmospheric microwave brightness temperatures T(B) from layers of precipitation-sized ice of variable bulk density and ice water content (IWC) are presented. It is shown that the 85-GHz T(B) depends essentially on the ice optical thickness. The results demonstrate the potential usefulness of scattering-based channels for characterizing the ice phase and suggest a top-down methodology for retrieval of cloud vertical structure and precipitation estimation from multifrequency passive microwave measurements. Attention is also given to radiative transfer model results based on the multiparameter radar data initialization from the Cooperative Huntsville Meteorological Experiment (COHMEX) in northern Alabama. It is shown that brightness temperature warming effects due to the inclusion of a cloud liquid water profile are especially significant at 85 GHz during later stages of cloud evolution.

AIRS Storm Front Approaching California (animation)

NASA Technical Reports Server (NTRS)

2005-01-01

[figure removed for brevity, see original site] Click on the image for the AIRS Storm Front Approaching California Animation

NASA's Atmospheric Infrared Sounder instrument is able to peel back cloud cover to reveal 3-D structure of a storm's water vapor content, information that can be used to improve weather forecast models.

In this animation the initial visible cloud image series shows a front moving toward the West Coast of the United States as a low pressure area moves into the Pacific Northwest. The 'Pineapple Express,' a stream of moisture that originates in the tropics South of Hawaii and usually crosses Mexico to enter New Mexico and Texas, has shifted Westward and is also visible moving into Baja California. The area preceding the front appears to be relatively clear in the visible images.

As the view shifts from the visible to the infrared wavelengths which highlight water vapor, we see both cloud areas contain heavy burdens of moisture. The area which appears clear in the visible images is seen to contain water vapor near the coastline as well. The viewpoint then rotates so that we can see the vertical cross section of the fronts. The variability of the vertical extent of water vapor and the amount is now clearly visible. The storm moving in from the Gulf of Alaska is more heavily laden with water vapor than that moving in from the Southwest. The moisture is concentrated in the lower atmosphere. The colors indicate the amount of water vapor present. Blue areas denote low water vapor content; green areas are medium water vapor content; red areas signify high water vapor content. The vertical grid for the final frame ranges from 250 millibar pressure at the top to 1000 millibar pressure at the bottom. The top is about 10 km (6.2 miles) above the surface of the Earth.

The Atmospheric Infrared Sounder Experiment, with its visible, infrared, and microwave detectors, provides a three-dimensional look at Earth's weather. Working in tandem, the three instruments can make simultaneous observations all the way down to the Earth's surface, even in the presence of heavy clouds. With more than 2,000 channels sensing different regions of the atmosphere, the system creates a global, 3-D map of atmospheric temperature and humidity and provides information on clouds, greenhouse gases, and many other atmospheric phenomena. The AIRS Infrared Sounder Experiment flies onboard NASA's Aqua spacecraft and is managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif., under contract to NASA. JPL is a division of the California Institute of Technology in Pasadena.

Detection of water vapor on Jupiter

NASA Technical Reports Server (NTRS)

Larson, H. P.; Fink, U.; Treffers, R.; Gautier, T. N., III

1975-01-01

High-altitude (12.4 km) spectroscopic observations of Jupiter at 5 microns from the NASA 91.5 cm airborne infrared telescope have revealed 14 absorptions assigned to the rotation-vibration spectrum of water vapor. Preliminary analysis indicates a mixing ratio about 1 millionth for the vapor phase of water. Estimates of temperature (greater than about 300 K) and pressure (less than 20 atm) suggest observation of water deep in Jupiter's hot spots responsible for its 5 micron flux. Model-atmosphere calculations based on radiative-transfer theory may change these initial estimates and provide a better physical picture of Jupiter's atmosphere below the visible cloud tops.

Clouds, Wind and the Biogeography of Central American Cloud Forests: Remote Sensing, Atmospheric Modeling, and Walking in the Jungle

NASA Astrophysics Data System (ADS)

Lawton, R.; Nair, U. S.

2011-12-01

Cloud forests stand at the core of the complex of montane ecosystems that provide the backbone to the multinational Mesoamerican Biological Corridor, which seeks to protect a biodiversity conservation "hotspot" of global significance in an area of rapidly changing land use. Although cloud forests are generally defined by frequent and prolonged immersion in cloud, workers differ in their feelings about "frequent" and "prolonged", and quantitative assessments are rare. Here we focus on the dry season, in which the cloud and mist from orographic cloud plays a critical role in forest water relations, and discuss remote sensing of orographic clouds, and regional and atmospheric modeling at several scales to quantitatively examine the distribution of the atmospheric conditions that characterize cloud forests. Remote sensing using data from GOES reveals diurnal and longer scale patterns in the distribution of dry season orographic clouds in Central America at both regional and local scales. Data from MODIS, used to calculate the base height of orographic cloud banks, reveals not only the geographic distributon of cloud forest sites, but also striking regional variation in the frequency of montane immersion in orographic cloud. At a more local scale, wind is known to have striking effects on forest structure and species distribution in tropical montane ecosystems, both as a general mechanical stress and as the major agent of ecological disturbance. High resolution regional atmospheric modeling using CSU RAMS in the Monteverde cloud forests of Costa Rica provides quantitative information on the spatial distribution of canopy level winds, insight into the spatial structure and local dynamics of cloud forest communities. This information will be useful in not only in local conservation planning and the design of the Mesoamerican Biological Corridor, but also in assessments of the sensitivity of cloud forests to global and regional climate changes.

Cloud-radiative effects on implied oceanic energy transport as simulated by atmospheric general circulation models

NASA Technical Reports Server (NTRS)

Gleckler, P. J.; Randall, D. A.; Boer, G.; Colman, R.; Dix, M.; Galin, V.; Helfand, M.; Kiehl, J.; Kitoh, A.; Lau, W.

1995-01-01

This paper summarizes the ocean surface net energy flux simulated by fifteen atmospheric general circulation models constrained by realistically-varying sea surface temperatures and sea ice as part of the Atmospheric Model Intercomparison Project. In general, the simulated energy fluxes are within the very large observational uncertainties. However, the annual mean oceanic meridional heat transport that would be required to balance the simulated surface fluxes is shown to be critically sensitive to the radiative effects of clouds, to the extent that even the sign of the Southern Hemisphere ocean heat transport can be affected by the errors in simulated cloud-radiation interactions. It is suggested that improved treatment of cloud radiative effects should help in the development of coupled atmosphere-ocean general circulation models.

Life Cycle of Tropical Convection and Anvil in Observations and Models

NASA Astrophysics Data System (ADS)

McFarlane, S. A.; Hagos, S. M.; Comstock, J. M.

2011-12-01

Tropical convective clouds are important elements of the hydrological cycle and produce extensive cirrus anvils that strongly affect the tropical radiative energy balance. To improve simulations of the global water and energy cycles and accurately predict both precipitation and cloud radiative feedbacks, models need to realistically simulate the lifecycle of tropical convection, including the formation and radiative properties of ice anvil clouds. By combining remote sensing datasets from precipitation and cloud radars at the Atmospheric Radiation Measurement (ARM) Darwin site with geostationary satellite data, we can develop observational understanding of the lifetime of convective systems and the links between the properties of convective systems and their associated anvil clouds. The relationships between convection and anvil in model simulations can then be compared to those seen in the observations to identify areas for improvement in the model simulations. We identify and track tropical convective systems in the Tropical Western Pacific using geostationary satellite observations. We present statistics of the tropical convective systems including size, age, and intensity and classify the lifecycle stage of each system as developing, mature, or dissipating. For systems that cross over the ARM Darwin site, information on convective intensity and anvil properties are obtained from the C-Pol precipitation radar and MMCR cloud radar, respectively, and are examined as a function of the system lifecycle. Initial results from applying the convective identification and tracking algorithm to a tropical simulation from the Weather Research and Forecasting (WRF) model run show that the model produces reasonable overall statistics of convective systems, but details of the life cycle (such as diurnal cycle, system tracks) differ from the observations. Further work will focus on the role of atmospheric temperature and moisture profiles in the model's convective life cycle.

The Intercomparison of 3D Radiation Codes (I3RC): Showcasing Mathematical and Computational Physics in a Critical Atmospheric Application

NASA Astrophysics Data System (ADS)

Davis, A. B.; Cahalan, R. F.

2001-05-01

The Intercomparison of 3D Radiation Codes (I3RC) is an on-going initiative involving an international group of over 30 researchers engaged in the numerical modeling of three-dimensional radiative transfer as applied to clouds. Because of their strong variability and extreme opacity, clouds are indeed a major source of uncertainty in the Earth's local radiation budget (at GCM grid scales). Also 3D effects (at satellite pixel scales) invalidate the standard plane-parallel assumption made in the routine of cloud-property remote sensing at NASA and NOAA. Accordingly, the test-cases used in I3RC are based on inputs and outputs which relate to cloud effects in atmospheric heating rates and in real-world remote sensing geometries. The main objectives of I3RC are to (1) enable participants to improve their models, (2) publish results as a community, (3) archive source code, and (4) educate. We will survey the status of I3RC and its plans for the near future with a special emphasis on the mathematical models and computational approaches. We will also describe some of the prime applications of I3RC's efforts in climate models, cloud-resolving models, and remote-sensing observations of clouds, or that of the surface in their presence. In all these application areas, computational efficiency is the main concern and not accuracy. One of I3RC's main goals is to document the performance of as wide a variety as possible of three-dimensional radiative transfer models for a small but representative number of ``cases.'' However, it is dominated by modelers working at the level of linear transport theory (i.e., they solve the radiative transfer equation) and an overwhelming majority of these participants use slow-but-robust Monte Carlo techniques. This means that only a small portion of the efficiency vs. accuracy vs. flexibility domain is currently populated by I3RC participants. To balance this natural clustering the present authors have organized a systematic outreach towards modelers that have used approximate methods in radiation transport. In this context, different, presumably simpler, equations (such as diffusion) are used in order to make a significant gain on the efficiency axis. We will describe in some detail the most promising approaches to approximate 3D radiative transfer in clouds. Somewhat paradoxically, and in spite of its importance in the above-mentioned applications, approximate radiative transfer modeling lags significantly behind its exact counterpart because the required mathematical and computational culture is essentially alien to the native atmospheric radiation community. I3RC is receiving enough funding from NASA/HQ and DOE/ARM for its essential operations out of NASA/GSFC. However, this does not cover the time and effort of any of the participants; so only existing models were entered. At present, none of inherently approximate methods are represented, only severe truncations of some exact methods. We therefore welcome the Math/Geo initiative at NSF which should enable the proper consortia of experts in atmospheric radiation and in applied mathematics to fill an important niche.

Covariance Between Arctic Sea Ice and Clouds Within Atmospheric State Regimes at the Satellite Footprint Level

NASA Technical Reports Server (NTRS)

Taylor, Patrick C.; Kato, Seiji; Xu, Kuan-Man; Cai, Ming

2015-01-01

Understanding the cloud response to sea ice change is necessary for modeling Arctic climate. Previous work has primarily addressed this problem from the interannual variability perspective. This paper provides a refined perspective of sea ice-cloud relationship in the Arctic using a satellite footprint-level quantification of the covariance between sea ice and Arctic low cloud properties from NASA A-Train active remote sensing data. The covariances between Arctic low cloud properties and sea ice concentration are quantified by first partitioning each footprint into four atmospheric regimes defined using thresholds of lower tropospheric stability and mid-tropospheric vertical velocity. Significant regional variability in the cloud properties is found within the atmospheric regimes indicating that the regimes do not completely account for the influence of meteorology. Regional anomalies are used to account for the remaining meteorological influence on clouds. After accounting for meteorological regime and regional influences, a statistically significant but weak covariance between cloud properties and sea ice is found in each season for at least one atmospheric regime. Smaller average cloud fraction and liquid water are found within footprints with more sea ice. The largest-magnitude cloud-sea ice covariance occurs between 500m and 1.2 km when the lower tropospheric stability is between 16 and 24 K. The covariance between low cloud properties and sea ice is found to be largest in fall and is accompanied by significant changes in boundary layer temperature structure where larger average near-surface static stability is found at larger sea ice concentrations.

Covariance between Arctic sea ice and clouds within atmospheric state regimes at the satellite footprint level.

PubMed

Taylor, Patrick C; Kato, Seiji; Xu, Kuan-Man; Cai, Ming

2015-12-27

Understanding the cloud response to sea ice change is necessary for modeling Arctic climate. Previous work has primarily addressed this problem from the interannual variability perspective. This paper provides a refined perspective of sea ice-cloud relationship in the Arctic using a satellite footprint-level quantification of the covariance between sea ice and Arctic low cloud properties from NASA A-Train active remote sensing data. The covariances between Arctic low cloud properties and sea ice concentration are quantified by first partitioning each footprint into four atmospheric regimes defined using thresholds of lower tropospheric stability and midtropospheric vertical velocity. Significant regional variability in the cloud properties is found within the atmospheric regimes indicating that the regimes do not completely account for the influence of meteorology. Regional anomalies are used to account for the remaining meteorological influence on clouds. After accounting for meteorological regime and regional influences, a statistically significant but weak covariance between cloud properties and sea ice is found in each season for at least one atmospheric regime. Smaller average cloud fraction and liquid water are found within footprints with more sea ice. The largest-magnitude cloud-sea ice covariance occurs between 500 m and 1.2 km when the lower tropospheric stability is between 16 and 24 K. The covariance between low cloud properties and sea ice is found to be largest in fall and is accompanied by significant changes in boundary layer temperature structure where larger average near-surface static stability is found at larger sea ice concentrations.

Mapping Nuclear Fallout Using the Weather Research & Forecasting (WRF) Model

DTIC Science & Technology

2012-09-01

relevant modules, originally designed to predict the settling of volcanic ash, such that a stabilized cloud of nuclear particulate is initialized...within the model. This modified code is then executed for various atmospheric test explosions and the results are qualitatively and quantitatively...HYSPLIT Simulation ....................................... 44  Figure 7. WRF Fallout Prediction for Test Shot George, 0.8 R/h at H+1

Review study and evaluation of possible flight experiments relating to cloud physics experiments in space

NASA Technical Reports Server (NTRS)

Hunt, R. J.; Wu, S. T.

1976-01-01

The general objectives of the Zero-Gravity Atmospheric Cloud Physics Laboratory Program are to improve the level of knowledge in atmospheric cloud research by placing at the disposal of the terrestrial-bound atmospheric cloud physicist a laboratory that can be operated in the environment of zero-gravity or near zero-gravity. This laboratory will allow studies to be performed without mechanical, aerodynamic, electrical, or other techniques to support the object under study. The inhouse analysis of the Skylab 3 and 4 experiments in dynamics of oscillations, rotations, collisions and coalescence of water droplets under low gravity-environment is presented.

Infrared remote sensing of the vertical and horizontal distribution of clouds

NASA Technical Reports Server (NTRS)

Chahine, M. T.; Haskins, R. D.

1982-01-01

An algorithm has been developed to derive the horizontal and vertical distribution of clouds from the same set of infrared radiance data used to retrieve atmospheric temperature profiles. The method leads to the determination of the vertical atmospheric temperature structure and the cloud distribution simultaneously, providing information on heat sources and sinks, storage rates and transport phenomena in the atmosphere. Experimental verification of this algorithm was obtained using the 15-micron data measured by the NOAA-VTPR temperature sounder. After correcting for water vapor emission, the results show that the cloud cover derived from 15-micron data is less than that obtained from visible data.

AERI Observations of Antarctic Clouds Properties During AWARE

NASA Astrophysics Data System (ADS)

Gero, P. J.; Rowe, P. M.; Walden, V. P.

2017-12-01

The ARM West Antarctic Radiation Experiment (AWARE) was a recent field campaign by the US Dept. of Energy's Atmospheric Radiation Measurement (ARM) program, in collaboration with the National Science Foundation, to measure the state of the atmosphere, the surface energy balance, and cloud properties in Antarctica. The main observing facility for AWARE, located near McMurdo Station, consisted of a wide variety of instrumentation, including an eddy-covariance system, surface aerosol measurements, cloud radar and lidar, broadband radiometers, microwave radiometer, and an infrared spectroradiometer (AERI). Collectively these measurements can be used to improve our understanding of the connections between the atmospheric state, cloud processes, and their effects on the surface energy budget. Thus, AWARE data have the potential to revolutionize our understanding of how the atmosphere and clouds impact the surface energy budget in this important region. The Atmospheric Emitted Radiance Interferometer (AERI) is a ground-based instrument developed at the University of Wisconsin-Madison that measures downwelling thermal infrared radiance from the atmosphere. Observations are made in the 400-3020 cm-1 (3.3-19 μm) spectral range with a resolution of 1 cm-1, with an accuracy better than 1% of ambient radiance. These observations can be used to obtain vertical profiles of tropospheric temperature and water vapor in the lower troposphere, as well as measurements of the concentration of various trace gases and microphysical and optical properties of clouds. We present some preliminary results from the AERI dataset from AWARE, including analysis of the downwelling radiation and cloud structure over the annual cycle.

[Atmospheric Influences Analysis on the Satellite Passive Microwave Remote Sensing].

PubMed

Qiu, Yu-bao; Shi, Li-juan; Shi, Jian-cheng; Zhao, Shao-jie

2016-02-01

Passive microwave remote sensing offers its all-weather work capabilities, but atmospheric influences on satellite microwave brightness temperature were different under different atmospheric conditions and environments. In order to clarify atmospheric influences on Advanced Microwave Scanning Radiometer-Earth Observing System (AMSR-E), atmospheric radiation were simulated based on AMSR-E configuration under clear sky and cloudy conditions, by using radiative transfer model and atmospheric conditions data. Results showed that atmospheric water vapor was the major factor for atmospheric radiation under clear sky condition. Atmospheric transmittances were almost above 0.98 at AMSR-E's low frequencies (< 18.7 GHz) and the microwave brightness temperature changes caused by atmosphere can be ignored in clear sky condition. Atmospheric transmittances at 36.5 and 89 GHz were 0.896 and 0.756 respectively. The effects of atmospheric water vapor needed to be corrected when using microwave high-frequency channels to inverse land surface parameters in clear sky condition. But under cloud cover or cloudy conditions, cloud liquid water was the key factor to cause atmospheric radiation. When sky was covered by typical stratus cloud, atmospheric transmittances at 10.7, 18.7 and 36.5 GHz were 0.942, 0.828 and 0.605 respectively. Comparing with the clear sky condition, the down-welling atmospheric radiation caused by cloud liquid water increased up to 75.365 K at 36.5 GHz. It showed that the atmospheric correction under different clouds covered condition was the primary work to improve the accuracy of land surface parameters inversion of passive microwave remote sensing. The results also provided the basis for microwave atmospheric correction algorithm development. Finally, the atmospheric sounding data was utilized to calculate the atmospheric transmittance of Hailaer Region, Inner Mongolia province, in July 2013. The results indicated that atmospheric transmittances were close to 1 at C-band and X-band. 89 GHz was greatly influenced by water vapor and its atmospheric transmittance was not more than 0.7. Atmospheric transmittances in Hailaer Region had a relatively stable value in summer, but had about 0.1 fluctuations with the local water vapor changes.

Diabatic forcing and intialization with assimilation of cloud water and rainwater in a forecast model

NASA Technical Reports Server (NTRS)

Raymond, William H.; Olson, William S.; Callan, Geary

1995-01-01

In this study, diabatic forcing, and liquid water assimilation techniques are tested in a semi-implicit hydrostatic regional forecast model containing explicit representations of grid-scale cloud water and rainwater. Diabatic forcing, in conjunction with diabatic contributions in the initialization, is found to help the forecast retain the diabatic signal found in the liquid water or heating rate data, consequently reducing the spinup time associated with grid-scale precipitation processes. Both observational Special Sensor Microwave/Imager (SSM/I) and model-generated data are used. A physical retrieval method incorporating SSM/I radiance data is utilized to estimate the 3D distribution of precipitating storms. In the retrieval method the relationship between precipitation distributions and upwelling microwave radiances is parameterized, based upon cloud ensemble-radiative model simulations. Regression formulae relating vertically integrated liquid and ice-phase precipitation amounts to latent heating rates are also derived from the cloud ensemble simulations. Thus, retrieved SSM/I precipitation structures can be used in conjunction with the regression-formulas to infer the 3D distribution of latent heating rates. These heating rates are used directly in the forecast model to help initiate Tropical Storm Emily (21 September 1987). The 14-h forecast of Emily's development yields atmospheric precipitation water contents that compare favorably with coincident SSM/I estimates.

A Bird’s Eye View: Development of an Operational ARM Unmanned Aerial Capability for Atmospheric Research in Arctic Alaska

DOE PAGES

de Boer, Gijs; Ivey, Mark; Schmid, Beat; ...

2018-03-14

Here, we present that unmanned aerial capabilities offer exciting new perspectives on the Arctic atmosphere and the US Department of Energy is working with partners to offer such perspectives to the research community. Thorough understanding of aerosols, clouds, boundary layer structure and radiation is required to improve representation of the Arctic atmosphere in weather forecasting and climate models. To develop such understanding, new perspectives are needed to provide details on the vertical structure and spatial variability of key atmospheric properties, along with information over difficult-to-reach surfaces such as newly-forming sea ice. Over the last three years, the US Department ofmore » Energy (DOE) has supported various flight campaigns using unmanned aircraft systems (UAS, also known as UAVs and drones) and tethered balloon systems (TBS) at Oliktok Point, Alaska. These activities have featured in-situ measurements of thermodynamic state, turbulence, radiation, aerosol properties, cloud microphysics and turbulent fluxes to provide a detailed characterization of the lower atmosphere. Alongside a suite of active and passive ground-based sensors and radiosondes deployed by the DOE Atmospheric Radiation Measurement (ARM) program through the third ARM Mobile Facility (AMF-3), these flight activities demonstrate the ability of such platforms to provide critically-needed information. In addition to providing new and unique datasets, lessons learned during initial campaigns have assisted toward the development of an exciting new community resource.« less

A Bird’s Eye View: Development of an Operational ARM Unmanned Aerial Capability for Atmospheric Research in Arctic Alaska

DOE Office of Scientific and Technical Information (OSTI.GOV)

de Boer, Gijs; Ivey, Mark; Schmid, Beat

Here, we present that unmanned aerial capabilities offer exciting new perspectives on the Arctic atmosphere and the US Department of Energy is working with partners to offer such perspectives to the research community. Thorough understanding of aerosols, clouds, boundary layer structure and radiation is required to improve representation of the Arctic atmosphere in weather forecasting and climate models. To develop such understanding, new perspectives are needed to provide details on the vertical structure and spatial variability of key atmospheric properties, along with information over difficult-to-reach surfaces such as newly-forming sea ice. Over the last three years, the US Department ofmore » Energy (DOE) has supported various flight campaigns using unmanned aircraft systems (UAS, also known as UAVs and drones) and tethered balloon systems (TBS) at Oliktok Point, Alaska. These activities have featured in-situ measurements of thermodynamic state, turbulence, radiation, aerosol properties, cloud microphysics and turbulent fluxes to provide a detailed characterization of the lower atmosphere. Alongside a suite of active and passive ground-based sensors and radiosondes deployed by the DOE Atmospheric Radiation Measurement (ARM) program through the third ARM Mobile Facility (AMF-3), these flight activities demonstrate the ability of such platforms to provide critically-needed information. In addition to providing new and unique datasets, lessons learned during initial campaigns have assisted toward the development of an exciting new community resource.« less

Tropical Depression 6 (Florence) in the Atlantic

NASA Technical Reports Server (NTRS)

2006-01-01

[figure removed for brevity, see original site] [figure removed for brevity, see original site] Microwave ImageVisible Light Image

These infrared, microwave, and visible images were created with data retrieved by the Atmospheric Infrared Sounder (AIRS) on NASA's Aqua satellite.

Infrared Image Because infrared radiation does not penetrate through clouds, AIRS infrared images show either the temperature of the cloud tops or the surface of the Earth in cloud-free regions. The lowest temperatures (in purple) are associated with high, cold cloud tops that make up the top of the storm. In cloud-free areas the AIRS instrument will receive the infrared radiation from the surface of the Earth, resulting in the warmest temperatures (orange/red).

Microwave Image AIRS data used to create the microwave images come from the microwave radiation emitted by Earth's atmosphere which is then received by the instrument. It shows where the heaviest rainfall is taking place (in blue) in the storm. Blue areas outside of the storm, where there are either some clouds or no clouds, indicate where the sea surface shines through.

Vis/NIR Image The AIRS instrument suite contains a sensor that captures light in the visible/near-infrared portion of the electromagnetic spectrum. These 'visible' images are similar to a snapshot taken with your camera.

The Atmospheric Infrared Sounder Experiment, with its visible, infrared, and microwave detectors, provides a three-dimensional look at Earth's weather. Working in tandem, the three instruments can make simultaneous observations all the way down to the Earth's surface, even in the presence of heavy clouds. With more than 2,000 channels sensing different regions of the atmosphere, the system creates a global, 3-D map of atmospheric temperature and humidity and provides information on clouds, greenhouse gases, and many other atmospheric phenomena. The AIRS Infrared Sounder Experiment flies onboard NASA's Aqua spacecraft and is managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif., under contract to NASA. JPL is a division of the California Institute of Technology in Pasadena.

Clouds in the atmosphere of the super-Earth exoplanet GJ 1214b.

PubMed

Kreidberg, Laura; Bean, Jacob L; Désert, Jean-Michel; Benneke, Björn; Deming, Drake; Stevenson, Kevin B; Seager, Sara; Berta-Thompson, Zachory; Seifahrt, Andreas; Homeier, Derek

2014-01-02

Recent surveys have revealed that planets intermediate in size between Earth and Neptune ('super-Earths') are among the most common planets in the Galaxy. Atmospheric studies are the next step towards developing a comprehensive understanding of this new class of object. Much effort has been focused on using transmission spectroscopy to characterize the atmosphere of the super-Earth archetype GJ 1214b (refs 7 - 17), but previous observations did not have sufficient precision to distinguish between two interpretations for the atmosphere. The planet's atmosphere could be dominated by relatively heavy molecules, such as water (for example, a 100 per cent water vapour composition), or it could contain high-altitude clouds that obscure its lower layers. Here we report a measurement of the transmission spectrum of GJ 1214b at near-infrared wavelengths that definitively resolves this ambiguity. The data, obtained with the Hubble Space Telescope, are sufficiently precise to detect absorption features from a high mean-molecular-mass atmosphere. The observed spectrum, however, is featureless. We rule out cloud-free atmospheric models with compositions dominated by water, methane, carbon monoxide, nitrogen or carbon dioxide at greater than 5σ confidence. The planet's atmosphere must contain clouds to be consistent with the data.

ACTRIS Aerosol, Clouds and Trace Gases Research Infrastructure

NASA Astrophysics Data System (ADS)

Pappalardo, Gelsomina

2018-04-01

The Aerosols, Clouds and Trace gases Research Infrastructure (ACTRIS) is a distributed infrastructure dedicated to high-quality observation of aerosols, clouds, trace gases and exploration of their interactions. It will deliver precision data, services and procedures regarding the 4D variability of clouds, short-lived atmospheric species and the physical, optical and chemical properties of aerosols to improve the current capacity to analyse, understand and predict past, current and future evolution of the atmospheric environment.

Modeling of Cloud/Radiation Processes for Tropical Anvils

DTIC Science & Technology

1992-11-30

absorption assumption. The band 800-980 cm-l is located in the atmospheric window, where the greenhouse effect of clouds is most pronounced. It can be...9a) is always positive, corresponding to the heating of the earth-atmosphere system due to the greenhouse effect of clouds, while the solar cloud...observed midlatitude cirrus cases, the IR greenhouse effect outweighs the solar albedo effect. The degree of the greenhouse effect involving cirrus

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bony, Sandrine; Stevens, Bjorn; Coppin, David

General circulation models show that as the surface temperature increases, the convective anvil clouds shrink. By analyzing radiative–convective equilibrium simulations, our work shows that this behavior is rooted in basic energetic and thermodynamic properties of the atmosphere: As the climate warms, the clouds rise and remain at nearly the same temperature, but find themselves in a more stable atmosphere; this enhanced stability reduces the convective outflow in the upper troposphere and decreases the anvil cloud fraction. By warming the troposphere and increasing the upper-tropospheric stability, the clustering of deep convection also reduces the convective outflow and the anvil cloud fraction.more » When clouds are radiatively active, this robust coupling between temperature, high clouds, and circulation exerts a positive feedback on convective aggregation and favors the maintenance of strongly aggregated atmospheric states at high temperatures. This stability iris mechanism likely contributes to the narrowing of rainy areas as the climate warms. Whether or not it influences climate sensitivity requires further investigation.« less

Clouds and more: ARM climate modeling best estimate data: A new data product for climate studies

DOE PAGES

Xie, Shaocheng; McCoy, Renata B.; Klein, Stephen A.; ...

2010-01-01

The U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Program (www.arm.gov) was created in 1989 to address scientific uncertainties related to global climate change, with a focus on the crucial role of clouds and their influence on the transfer of radiation atmosphere. Here, a central activity is the acquisition of detailed observations of clouds and radiation, as well as related atmospheric variables for climate model evaluation and improvement.

Thermodynamic control of anvil cloud amount

PubMed Central

Bony, Sandrine; Stevens, Bjorn; Coppin, David; Becker, Tobias; Reed, Kevin A.; Voigt, Aiko

2016-01-01

General circulation models show that as the surface temperature increases, the convective anvil clouds shrink. By analyzing radiative–convective equilibrium simulations, we show that this behavior is rooted in basic energetic and thermodynamic properties of the atmosphere: As the climate warms, the clouds rise and remain at nearly the same temperature, but find themselves in a more stable atmosphere; this enhanced stability reduces the convective outflow in the upper troposphere and decreases the anvil cloud fraction. By warming the troposphere and increasing the upper-tropospheric stability, the clustering of deep convection also reduces the convective outflow and the anvil cloud fraction. When clouds are radiatively active, this robust coupling between temperature, high clouds, and circulation exerts a positive feedback on convective aggregation and favors the maintenance of strongly aggregated atmospheric states at high temperatures. This stability iris mechanism likely contributes to the narrowing of rainy areas as the climate warms. Whether or not it influences climate sensitivity requires further investigation. PMID:27412863

Thermodynamic control of anvil cloud amount

DOE PAGES

Bony, Sandrine; Stevens, Bjorn; Coppin, David; ...

2016-07-13

General circulation models show that as the surface temperature increases, the convective anvil clouds shrink. By analyzing radiative–convective equilibrium simulations, our work shows that this behavior is rooted in basic energetic and thermodynamic properties of the atmosphere: As the climate warms, the clouds rise and remain at nearly the same temperature, but find themselves in a more stable atmosphere; this enhanced stability reduces the convective outflow in the upper troposphere and decreases the anvil cloud fraction. By warming the troposphere and increasing the upper-tropospheric stability, the clustering of deep convection also reduces the convective outflow and the anvil cloud fraction.more » When clouds are radiatively active, this robust coupling between temperature, high clouds, and circulation exerts a positive feedback on convective aggregation and favors the maintenance of strongly aggregated atmospheric states at high temperatures. This stability iris mechanism likely contributes to the narrowing of rainy areas as the climate warms. Whether or not it influences climate sensitivity requires further investigation.« less

Simulating halos and coronas in their atmospheric environment.

PubMed

David Gedzelman, Stanley

2008-12-01

Models are developed that simulate the light and color of the sky and of circular halos and coronas as a function of atmospheric pressure, cloud height, width, and optical depth, solar zenith angle, aerosol concentration and size, and ozone content. Halos, coronas, and skylight are treated as singly scattered sunbeams that are depleted in their passage through the atmosphere and cloud. Multiple scattering is included only for background cloud light. Halos produced by hexagonal crystal prisms and coronas produced by monodisperse droplets are visible for cloud optical depths in the range 0.0003

Seasonality of Forcing by Carbonaceous Aerosols

NASA Astrophysics Data System (ADS)

Habib, G.; Bond, T.; Rasch, P. J.; Coleman, D.

2006-12-01

Aerosols can influence the energy balance of Earth-Atmosphere system with profound effect on regional climate. Atmospheric processes, such as convection, scavenging, wet and dry deposition, govern the lifetime and location of aerosol; emissions affect its quantity and location. Both affect climate forcing. Here we investigate the effect of seasonality in emissions and atmospheric processes on radiative forcing by carbonaceous aerosols, focusing on aerosol from fossil fuel and biofuel. Because aerosol lifetime is seasonal, ignoring the seasonality of sources such as residential biofuel may introduce a bias in aerosol burden and therefore in predicted climate forcing. We present a global emission inventory of carbonaceous aerosols with seasonality, and simulate atmospheric concentrations using the Community Atmosphere Model (CAM). We discuss where and when the seasonality of emissions and atmospheric processes has strong effects on atmospheric burden, lifetime, climate forcing and aerosol optical depth (AOD). Previous work has shown that aerosol forcing is higher in summer than in winter, and has identified the importance of aerosol above cloud in determining black carbon forcing. We show that predicted cloud height is a very important factor in determining normalized radiative forcing (forcing per mass), especially in summer. This can affect the average summer radiative forcing by nearly 50%. Removal by cloud droplets is the dominant atmospheric cleansing mechanism for carbonaceous aerosols. We demonstrate the modeled seasonality of removal processes and compare the importance of scavenging by warm and cold clouds. Both types of clouds contribute significantly to aerosol removal. We estimate uncertainty in direct radiative forcing due to scavenging by tagging the aerosol which has experienced cloud interactions. Finally, seasonal variations offer an opportunity to assess modeled processes when a single process dominates variability. We identify regions where aerosol burden is most sensitive to convection and scavenging in warm and cold clouds, and compare seasonally modeled AOD with that retrieved by the Moderate Resolution Imaging Spectroradiometer (MODIS).

Microwave radiative transfer studies of precipitation

NASA Technical Reports Server (NTRS)

Bringi, V. N.; Vivekanandan, J.; Turk, F. Joseph

1993-01-01

Since the deployment of the DMSP SSM/I microwave imagers in 1987, increased utilization of passive microwave radiometry throughout the 10 - 100 GHz spectrum has occurred for measurement of atmospheric constituents and terrestrial surfaces. Our efforts have focused on observations and analysis of the microwave radiative transfer behavior of precipitating clouds. We have focused particular attention on combining both aircraft and SSM/I radiometer imagery with ground-based multiparameter radar observations. As part of this and the past NASA contract, we have developed a multi-stream, polarized radiative transfer model which incorporates scattering. The model has the capability to be initialized with cloud model output or multiparameter radar products. This model provides the necessary 'link' between the passive microwave radiometer and active microwave radar observations. This unique arrangement has allowed the brightness temperatures (TB) to be compared against quantities such as rainfall, liquid/ice water paths, and the vertical structure of the cloud. Quantification of the amounts of ice and water in precipitating clouds is required for understanding of the global energy balance.

Surface crystallization of supercooled water in clouds

PubMed Central

Tabazadeh, A.; Djikaev, Y. S.; Reiss, H.

2002-01-01

The process by which liquid cloud droplets homogeneously crystallize into ice is still not well understood. The ice nucleation process based on the standard and classical theory of homogeneous freezing initiates within the interior volume of a cloud droplet. Current experimental data on homogeneous freezing rates of ice in droplets of supercooled water, both in air and emulsion oil samples, show considerable scatter. For example, at −33°C, the reported volume-based freezing rates of ice in supercooled water vary by as many as 5 orders of magnitude, which is well outside the range of measurement uncertainties. Here, we show that the process of ice nucleus formation at the air (or oil)-liquid water interface may help to explain why experimental results on ice nucleation rates yield different results in different ambient phases. Our results also suggest that surface crystallization of ice in cloud droplets can explain why low amounts of supercooled water have been observed in the atmosphere near −40°C. PMID:12456877

Vertical Cloud Climatology During TC4 Derived from High-Altitude Aircraft Merged Lidar and Radar Profiles

NASA Technical Reports Server (NTRS)

Hlavka, Dennis; Tian, Lin; Hart, William; Li, Lihua; McGill, Matthew; Heymsfield, Gerald

2009-01-01

Aircraft lidar works by shooting laser pulses toward the earth and recording the return time and intensity of any of the light returning to the aircraft after scattering off atmospheric particles and/or the Earth s surface. The scattered light signatures can be analyzed to tell the exact location of cloud and aerosol layers and, with the aid of a few optical assumptions, can be analyzed to retrieve estimates of optical properties such as atmospheric transparency. Radar works in a similar fashion except it sends pulses toward earth at a much larger wavelength than lidar. Radar records the return time and intensity of cloud or rain reflection returning to the aircraft. Lidar can measure scatter from optically thin cirrus and aerosol layers whose particles are too small for the radar to detect. Radar can provide reflection profiles through thick cloud layers of larger particles that lidar cannot penetrate. Only after merging the two instrument products can accurate measurements of the locations of all layers in the full atmospheric column be achieved. Accurate knowledge of the vertical distribution of clouds is important information for understanding the Earth/atmosphere radiative balance and for improving weather/climate forecast models. This paper describes one such merged data set developed from the Tropical Composition, Cloud and Climate Coupling (TC4) experiment based in Costa Rica in July-August 2007 using the nadir viewing Cloud Physics Lidar (CPL) and the Cloud Radar System (CRS) on board the NASA ER-2 aircraft. Statistics were developed concerning cloud probability through the atmospheric column and frequency of the number of cloud layers. These statistics were calculated for the full study area, four sub-regions, and over land compared to over ocean across all available flights. The results are valid for the TC4 experiment only, as preferred cloud patterns took priority during mission planning. The TC4 Study Area was a very cloudy region, with cloudy profiles occurring 94 percent of the time during the ER-2 flights. One to three cloud layers were common, with the average calculated at 2.03 layers per profile. The upper troposphere had a cloud frequency generally over 30%, reaching 42 percent near 13 km during the study. There were regional differences. The Caribbean was much clearer than the Pacific regions. Land had a much higher frequency of high clouds than ocean areas. One region just south and west of Panama had a high probability of clouds below 15 km altitude with the frequency never dropping below 25% and reaching a maximum of 60% at 11-13 km altitude. These cloud statistics will help characterize the cloud volume for TC4 scientists as they try to understand the complexities of the tropical atmosphere.

Arctic ocean radiative fluxes and cloud forcing estimated from the ISCCP C2 cloud dataset, 1983-1990

NASA Technical Reports Server (NTRS)

Schweiger, Axel J.; Key, Jeffrey R.

1994-01-01

Radiative fluxes and cloud forcings for the ocean areas of the Arctic are computed from the monthly cloud product of the International Satellite Cloud Climatology Project (ISCCP) for 1983-90. Spatially averaged short-wave fluxes are compared well with climatological values, while downwelling longwave fluxes are significantly lower. This is probably due to the fact that the ISCCP cloud amounts are underestimates. Top-of-the-atmosphere radiative fluxes are in excellent agreement with measurements from the Earth Radiation Budget Experiment (ERBE). Computed cloud forcings indicate that clouds have a warming effect at the surface and at the top of the atmosphere during winter and a cooling effect during summer. The net radiative effect of clouds is larger at the surface during winter but greater at the top of the atmosphere during summer. Overall the net radiative effect of clouds at the top of the atmosphere is one of cooling. This is in contrast to a previous result from ERBE data showing arctic cloud forcings have a net warming effect. Sensitivities to errors in input parameters are generally greater during winter with cloud amount being the most important paarameter. During summer the surface radiation balance is most sensitive to errors in the measurements of surface reflectance. The results are encouraging, but the estimated error of 20 W/sq m in surface net radiative fluxes is too large, given that estimates of the net radiative warming effect due to a doubling of CO2 are on the order of 4 W/sq m. Because it is difficult to determine the accuracy of results with existing in situ observations, it is recommended that the development of improved algorithms for the retrieval of surface radiative properties be accompanied by the simultaneous assembly of validation datasets.

Clouds and the extratropical circulation response to global warming in a hierarchy of global atmosphere models

NASA Astrophysics Data System (ADS)

Voigt, A.

2017-12-01

Climate models project that global warming will lead to substantial changes in extratropical jet streams. Yet, many quantitative aspects of warming-induced jet stream changes remain uncertain, and recent work has indicated an important role of clouds and their radiative interactions. Here, I will investigate how cloud-radiative changes impact the zonal-mean extratropical circulation response under global warming using a hierarchy of global atmosphere models. I will first focus on aquaplanet setups with prescribed sea-surface temperatures (SSTs), which reproduce the model spread found in realistic simulations with interactive SSTs. Simulations with two CMIP5 models MPI-ESM and IPSL-CM5A and prescribed clouds show that half of the circulation response can be attributed to cloud changes. The rise of tropical high-level clouds and the upward and poleward movement of midlatitude high-level clouds lead to poleward jet shifts. High-latitude low-level cloud changes shift the jet poleward in one model but not in the other. The impact of clouds on the jet operates via the atmospheric radiative forcing that is created by the cloud changes and is qualitatively reproduced in a dry Held-Suarez model, although the latter is too sensitive because of its simplified treatment of diabatic processes. I will then show that the aquaplanet results also hold when the models are used in a realistic setup that includes continents and seasonality. I will further juxtapose these prescribed-SST simulations with interactive-SST simulations and show that atmospheric and surface cloud-radiative interactions impact the jet poleward jet shifts in about equal measure. Finally, I will discuss the cloud impact on regional and seasonal circulation changes.

Diagnosing Cloud Biases in the GFDL AM3 Model With Atmospheric Classification

DOE Office of Scientific and Technical Information (OSTI.GOV)

Evans, Stuart; Marchand, Roger; Ackerman, Thomas

In this paper, we define a set of 21 atmospheric states, or recurring weather patterns, for a region surrounding the Atmospheric Radiation Measurement Program's Southern Great Plains site using an iterative clustering technique. The states are defined using dynamic and thermodynamic variables from reanalysis, tested for statistical significance with cloud radar data from the Southern Great Plains site, and are determined every 6 h for 14 years, creating a time series of atmospheric state. The states represent the various stages of the progression of synoptic systems through the region (e.g., warm fronts, warm sectors, cold fronts, cold northerly advection, andmore » high-pressure anticyclones) with a subset of states representing summertime conditions with varying degrees of convective activity. We use the states to classify output from the NOAA/Geophysical Fluid Dynamics Laboratory AM3 model to test the model's simulation of the frequency of occurrence of the states and of the cloud occurrence during each state. The model roughly simulates the frequency of occurrence of the states but exhibits systematic cloud occurrence biases. Comparison of observed and model-simulated International Satellite Cloud Climatology Project histograms of cloud top pressure and optical thickness shows that the model lacks high thin cloud under all conditions, but biases in thick cloud are state-dependent. Frontal conditions in the model do not produce enough thick cloud, while fair-weather conditions produce too much. Finally, we find that increasing the horizontal resolution of the model improves the representation of thick clouds under all conditions but has little effect on high thin clouds. However, increasing resolution also changes the distribution of states, causing an increase in total cloud occurrence bias.« less

Diagnosing Cloud Biases in the GFDL AM3 Model With Atmospheric Classification

NASA Astrophysics Data System (ADS)

Evans, Stuart; Marchand, Roger; Ackerman, Thomas; Donner, Leo; Golaz, Jean-Christophe; Seman, Charles

2017-12-01

We define a set of 21 atmospheric states, or recurring weather patterns, for a region surrounding the Atmospheric Radiation Measurement Program's Southern Great Plains site using an iterative clustering technique. The states are defined using dynamic and thermodynamic variables from reanalysis, tested for statistical significance with cloud radar data from the Southern Great Plains site, and are determined every 6 h for 14 years, creating a time series of atmospheric state. The states represent the various stages of the progression of synoptic systems through the region (e.g., warm fronts, warm sectors, cold fronts, cold northerly advection, and high-pressure anticyclones) with a subset of states representing summertime conditions with varying degrees of convective activity. We use the states to classify output from the NOAA/Geophysical Fluid Dynamics Laboratory AM3 model to test the model's simulation of the frequency of occurrence of the states and of the cloud occurrence during each state. The model roughly simulates the frequency of occurrence of the states but exhibits systematic cloud occurrence biases. Comparison of observed and model-simulated International Satellite Cloud Climatology Project histograms of cloud top pressure and optical thickness shows that the model lacks high thin cloud under all conditions, but biases in thick cloud are state-dependent. Frontal conditions in the model do not produce enough thick cloud, while fair-weather conditions produce too much. We find that increasing the horizontal resolution of the model improves the representation of thick clouds under all conditions but has little effect on high thin clouds. However, increasing resolution also changes the distribution of states, causing an increase in total cloud occurrence bias.

Diagnosing Cloud Biases in the GFDL AM3 Model With Atmospheric Classification

DOE PAGES

Evans, Stuart; Marchand, Roger; Ackerman, Thomas; ...

2017-11-16

In this paper, we define a set of 21 atmospheric states, or recurring weather patterns, for a region surrounding the Atmospheric Radiation Measurement Program's Southern Great Plains site using an iterative clustering technique. The states are defined using dynamic and thermodynamic variables from reanalysis, tested for statistical significance with cloud radar data from the Southern Great Plains site, and are determined every 6 h for 14 years, creating a time series of atmospheric state. The states represent the various stages of the progression of synoptic systems through the region (e.g., warm fronts, warm sectors, cold fronts, cold northerly advection, andmore » high-pressure anticyclones) with a subset of states representing summertime conditions with varying degrees of convective activity. We use the states to classify output from the NOAA/Geophysical Fluid Dynamics Laboratory AM3 model to test the model's simulation of the frequency of occurrence of the states and of the cloud occurrence during each state. The model roughly simulates the frequency of occurrence of the states but exhibits systematic cloud occurrence biases. Comparison of observed and model-simulated International Satellite Cloud Climatology Project histograms of cloud top pressure and optical thickness shows that the model lacks high thin cloud under all conditions, but biases in thick cloud are state-dependent. Frontal conditions in the model do not produce enough thick cloud, while fair-weather conditions produce too much. Finally, we find that increasing the horizontal resolution of the model improves the representation of thick clouds under all conditions but has little effect on high thin clouds. However, increasing resolution also changes the distribution of states, causing an increase in total cloud occurrence bias.« less

Cloud statistics over the Indonesian Maritime Continent during the first and second CPEA campaigns

NASA Astrophysics Data System (ADS)

Marzuki; Vonnisa, Mutya; Rahayu, Aulya; Hashiguchi, Hiroyuki

2017-06-01

Improvement of precipitation prediction requires an understanding of the organization mechanism, such as the initiation and evolution of organized convective systems. This paper is a follow-up of a previous study on cloud propagation over the Indonesian Maritime Continent (IMC). Here, the infrared blackbody brightness temperature data is analyzed. A comprehensive cloud statistics model, including span, speed, duration, all possible directions, and size was estimated by applying the modified tracking reflectivity echoes by correlation (TREC) method to time-latitude-longitude space. Comparisons were made to cloud statistics during the first and second campaigns of Coupling Processes in the Equatorial Atmosphere, hereinafter called CPEA-I and CPEA-II. Although the two campaigns were conducted in different monsoon seasons, the cloud propagation directions during each campaign were similar. The cloud systems moved in most directions, except north and east, and preferred southwestward, westward and northwestward movements. Thus, westward-moving clouds were more dominant than eastward-moving clouds, in agreement with previous studies. This feature is consistent with the prevailing easterly wind in the middle and upper troposphere despite the difference in low-level wind during each campaign. The two campaign periods were different due to the phase of the Madden-Julian Oscillation (MJO). CPEA-I took place over the active MJO phase, with larger-sized clouds than CPEA-II. Thus, the MJO had an enormous impact on cloud size, but such an impact was not significantly observed in the speed, lifetime, span and direction of propagation. In the two campaigns, clouds moved with a speed of 3-30 m s-1 and in duration from a few hours to longer than one day. Clouds with long spans and high speeds were generally observed during the strong vertical shear of horizontal winds. In contrast, clouds with short spans and low speeds were found in the more varied environment of the IMC, but were dominant over land, which may have been associated with the diurnal heating cycle. Finally, the present results showed more complex behavior than a previous study in the Bay of Bengal, indicating precipitation mechanisms over the IMC including interactions between large-scale atmospheric phenomena (e.g., monsoon and MJO) with the diurnal precipitation cycles.

Sonora: A New Generation Model Atmosphere Grid for Brown Dwarfs and Young Extrasolar Giant Planets

NASA Technical Reports Server (NTRS)

Marley, Mark S.; Saumon, Didier; Fortney, Jonathan J.; Morley, Caroline; Lupu, Roxana Elena; Freedman, Richard; Visscher, Channon

2017-01-01

Brown dwarf and giant planet atmospheric structure and composition has been studied both by forward models and, increasingly so, by retrieval methods. While indisputably informative, retrieval methods are of greatest value when judged in the context of grid model predictions. Meanwhile retrieval models can test the assumptions inherent in the forward modeling procedure. In order to provide a new, systematic survey of brown dwarf atmospheric structure, emergent spectra, and evolution, we have constructed a new grid of brown dwarf model atmospheres. We ultimately aim for our grid to span substantial ranges of atmospheric metallilcity, C/O ratios, cloud properties, atmospheric mixing, and other parameters. Spectra predicted by our modeling grid can be compared to both observations and retrieval results to aid in the interpretation and planning of future telescopic observations. We thus present Sonora, a new generation of substellar atmosphere models, appropriate for application to studies of L, T, and Y-type brown dwarfs and young extrasolar giant planets. The models describe the expected temperature-pressure profile and emergent spectra of an atmosphere in radiative-convective equilibrium for ranges of effective temperatures and gravities encompassing 200 less than or equal to T(sub eff) less than or equal to 2400 K and 2.5 less than or equal to log g less than or equal to 5.5. In our poster we briefly describe our modeling methodology, enumerate various updates since our group's previous models, and present our initial tranche of models for cloudless, solar metallicity, and solar carbon-to-oxygen ratio, chemical equilibrium atmospheres. These models will be available online and will be updated as opacities and cloud modeling methods continue to improve.

Cloud processing of organic compounds: Secondary organic aerosol and nitrosamine formation

NASA Astrophysics Data System (ADS)

Hutchings, James W., III

Cloud processing of atmospheric organic compounds has been investigated through field studies, laboratory experiments, and numerical modeling. Observational cloud chemistry studies were performed in northern Arizona and fog studies in central Pennsylvania. At both locations, the cloud and fogs showed low acidity due to neutralization by soil dust components (Arizona) and ammonia (Pennsylvania). The field observations showed substantial concentrations (20-5500 ng•L -1) of volatile organic compounds (VOC) in the cloud droplets. The potential generation of secondary organic aerosol mass through the processing of these anthropogenic VOCs was investigated through laboratory and modeling studies. Under simulated atmospheric conditions, in idealized solutions, benzene, toluene, ethylbenzene, and xylene (BTEX) degraded quickly in the aqueous phase with half lives of approximately three hours. The degradation process yielded less volatile products which would contribute to new aerosol mass upon cloud evaporation. However, when realistic cloud solutions containing natural organic matter were used in the experiments, the reaction kinetics decreased with increasing organic carbon content, resulting in half lives of approximately 7 hours. The secondary organic aerosol (SUA) mass formation potential of cloud processing of BTEX was evaluated. SOA mass formation by cloud processing of BTEX, while strongly dependent on the atmospheric conditions, could contribute up to 9% of the ambient atmospheric aerosol mass, although typically ˜1% appears realistic. Field observations also showed the occurrence of N-nitrosodimethylamine (NDMA), a potent carcinogen, in fogs and clouds (100-340 ng•L -1). Laboratory studies were conducted to investigate the formation of NDMA from nitrous acid and dimethylamine in the homogeneous aqueous phase within cloud droplets. While NDMA was produced in the cloud droplets, the low yields (<1%) observed could not explain observational concentrations. Therefore heterogeneous or gaseous formation of NDMA with partitioning to droplet must be the source of aqueous NDMA. Box-model calculations tended to demonstrate a predominance of a gas phase formation mechanism followed by partitioning into the cloud droplets. The calculations were consistent with field measurements of gaseous and aqueous NDMA concentrations. Measurements and model calculations showed that while NDMA is eventually photolyzed, it might persist in the atmosphere for hours.

Examination about the Impact of Thin Clouds in IFOV of GOSAT TANSO-FTS on Estimates of XCO2 in the Amazon

NASA Astrophysics Data System (ADS)

Oishi, Y.; Kamei, A.; Murakami, K.; Dupuy, E.; Yokota, Y.; Hiraki, K.; Ninomiya, K.; Saito, M.; Yoshida, Y.; Morino, I.; Nakajima, T. Y.; Yokota, T.; Matsunaga, T.

2013-12-01

Greenhouse gases Observing SATellite (GOSAT) was launched in 2009 to measure the global atmospheric CO2 and CH4 concentrations. GOSAT is equipped with two sensors: the Thermal And Near-infrared Sensor for carbon Observation-Fourier Transform Spectrometer (TANSO-FTS) and the Cloud and Aerosol Imager (TANSO-CAI). The presence of clouds in the instantaneous field-of-view (IFOV) of the FTS leads to incorrect estimates of the CO2 or CH4 concentration. To deal with this problem, the FTS data which are suspected to be cloud-contaminated must be identified and rejected. As a result, there are very few remaining FTS data in the region of tropical rainforest such as the Amazon. In the meanwhile the feasibility studies of GOSAT-2 started for more precise monitoring of atmospheric greenhouse gases than GOSAT in 2011. To improve the accuracy of estimates of the column-averaged dry air mole fraction of atmospheric CO2 (XCO2), we need to understand the present situation about cloud screening in the rain forest regions and to examine the cloud-contaminated data whose processing might be possible with improvement of instruments or algorithms. In this study we evaluated the impact of thin clouds on estimates of the XCO2 using an atmospheric radiative transfer code, which can simulate the spectrum at the top of the atmosphere under thin cloud conditions. First, we decided the input parameters, among which relative position of the sun and satellite to observation point, surface reflectance using cloud-free GOSAT data products in the Amazon, FTS L1B data products (radiance spectral data), FTS L2 data products (CO2 column abundance data), and CAI L3 data products (clear-sky reflectance data). The evaluation was performed by comparing depths of the CO2 absorption lines in output radiation spectra with varying CO2 concentrations and cloud conditions, cloud type, cloud optical depth, and cloud top altitude. We will present our latest results.

The Atmospheric Infrared Sounder Version 6 Cloud Products

NASA Technical Reports Server (NTRS)

Kahn, B. H.; Irion, F. W.; Dang, V. T.; Manning, E. M.; Nasiri, S. L.; Naud, C. M.; Blaisdell, J. M.; Schreier, M. M..; Yue, Q.; Bowman, K. W.;

Sound, infrasound, and sonic boom absorption by atmospheric clouds.

PubMed

Baudoin, Michaël; Coulouvrat, François; Thomas, Jean-Louis

2011-09-01

This study quantifies the influence of atmospheric clouds on propagation of sound and infrasound, based on an existing model [Gubaidulin and Nigmatulin, Int. J. Multiphase Flow 26, 207-228 (2000)]. Clouds are considered as a dilute and polydisperse suspension of liquid water droplets within a mixture of dry air and water vapor, both considered as perfect gases. The model is limited to low and medium altitude clouds, with a small ice content. Four physical mechanisms are taken into account: viscoinertial effects, heat transfer, water phase changes (evaporation and condensation), and vapor diffusion. Physical properties of atmospheric clouds (altitude, thickness, water content and droplet size distribution) are collected, along with values of the thermodynamical coefficients. Different types of clouds have been selected. Quantitative evaluation shows that, for low audible and infrasound frequencies, absorption within clouds is several orders of magnitude larger than classical absorption. The importance of phase changes and vapor diffusion is outlined. Finally, numerical simulations for nonlinear propagation of sonic booms indicate that, for thick clouds, attenuation can lead to a very large decay of the boom at the ground level. © 2011 Acoustical Society of America

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

NASA Technical Reports Server (NTRS)

Platnick, Steven E.

2011-01-01

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

Occurrence Locations, Dipole Tilt Angle Effects, and Plasma Cloud Drift Paths of Polar Cap Neutral Density Anomalies

NASA Astrophysics Data System (ADS)

Lin, C. S.; Sutton, E. K.; Huang, C. Y.; Cooke, D. L.

2018-02-01

Polar cap neutral density anomaly (PCNDA) with large mass density enhancements over the background has been frequently observed in the polar cap during magnetic storms. By tracing field lines to the magnetosphere from the polar ionosphere, we divide the polar cap into two regions, an open field line (OFL) region with field lines connecting to the magnetopause boundary and a distant tail field line (TFL) region threaded with magnetotail lobe field lines. A statistical study of neutral density observed by the Challenging Minisatellite Payload satellite during major magnetic storms with Dst < -100 from July 2001 to 2006 indicates that over 85% of density anomalies were detected in the TFL region, at about 18° to 25° equatorward the center of the OFL region. PCNDAs were frequently accompanied by plasma clouds with peak density greater than 105 #/cm3. Modeling of plasma cloud drift paths suggests that plasma clouds originating in the dayside ionosphere could convect through the OFL region following the zero-potential line and reach the PCNDA locations. Plasma clouds could become stagnate in the TFL region, allowing a long duration of collisions with the neutral gas and possibly contributing to heating of PCNDAs. The PCNDA observations are interpreted as evidence that traveling atmospheric disturbance could be generated in the nightside polar cap. From the PCNDA size and speed of sound at 400 km, we derive an initial energy deposition duration for producing traveling atmospheric disturbance in the range from 0.5 to 2.5 hr.

Evaluation of Cloud-Resolving Model Intercomparison Simulations Using TWP-ICE Observations: Precipitation and Cloud Structure

NASA Technical Reports Server (NTRS)

Varble, Adam; Fridlind, Ann M.; Zipser, Edward J.; Ackerman, Andrew S.; Chaboureau, Jean-Pierre; Fan, Jiwen; Hill, Adrian; McFarlane, Sally A.; Pinty, Jean-Pierre; Shipway, Ben

2011-01-01

The Tropical Warm Pool.International Cloud Experiment (TWP ]ICE) provided extensive observational data sets designed to initialize, force, and constrain atmospheric model simulations. In this first of a two ]part study, precipitation and cloud structures within nine cloud ]resolving model simulations are compared with scanning radar reflectivity and satellite infrared brightness temperature observations during an active monsoon period from 19 to 25 January 2006. Seven of nine simulations overestimate convective area by 20% or more leading to general overestimation of convective rainfall. This is balanced by underestimation of stratiform rainfall by 5% to 50% despite overestimation of stratiform area by up to 65% because of a preponderance of very low stratiform rain rates in all simulations. All simulations fail to reproduce observed radar reflectivity distributions above the melting level in convective regions and throughout the troposphere in stratiform regions. Observed precipitation ]sized ice reaches higher altitudes than simulated precipitation ]sized ice despite some simulations that predict lower than observed top ]of ]atmosphere infrared brightness temperatures. For the simulations that overestimate radar reflectivity aloft, graupel is the cause with one ]moment microphysics schemes whereas snow is the cause with two ]moment microphysics schemes. Differences in simulated radar reflectivity are more highly correlated with differences in mass mean melted diameter (Dm) than differences in ice water content. Dm is largely dependent on the mass ]dimension relationship and gamma size distribution parameters such as size intercept (N0) and shape parameter (m). Having variable density, variable N0, or m greater than zero produces radar reflectivities closest to those observed.

DSCOVR_EPIC_L2_MAIAC_01

Atmospheric Science Data Center

2018-06-25

... several atmospheric quantities including cloud mask and aerosol optical depth (AOD) required for atmospheric correction. The parameters ... Project Title:  DSCOVR Discipline:  Aerosol Clouds Version:  V1 Level:  L2 ...

Thermodynamic and cloud parameter retrieval using infrared spectral data

NASA Technical Reports Server (NTRS)

Zhou, Daniel K.; Smith, William L., Sr.; Liu, Xu; Larar, Allen M.; Huang, Hung-Lung A.; Li, Jun; McGill, Matthew J.; Mango, Stephen A.

2005-01-01

High-resolution infrared radiance spectra obtained from near nadir observations provide atmospheric, surface, and cloud property information. A fast radiative transfer model, including cloud effects, is used for atmospheric profile and cloud parameter retrieval. The retrieval algorithm is presented along with its application to recent field experiment data from the NPOESS Airborne Sounding Testbed - Interferometer (NAST-I). The retrieval accuracy dependence on cloud properties is discussed. It is shown that relatively accurate temperature and moisture retrievals can be achieved below optically thin clouds. For optically thick clouds, accurate temperature and moisture profiles down to cloud top level are obtained. For both optically thin and thick cloud situations, the cloud top height can be retrieved with an accuracy of approximately 1.0 km. Preliminary NAST-I retrieval results from the recent Atlantic-THORPEX Regional Campaign (ATReC) are presented and compared with coincident observations obtained from dropsondes and the nadir-pointing Cloud Physics Lidar (CPL).

Development of methods for inferring cloud thickness and cloud-base height from satellite radiance data

NASA Technical Reports Server (NTRS)

Smith, William L., Jr.; Minnis, Patrick; Alvarez, Joseph M.; Uttal, Taneil; Intrieri, Janet M.; Ackerman, Thomas P.; Clothiaux, Eugene

1993-01-01

Cloud-top height is a major factor determining the outgoing longwave flux at the top of the atmosphere. The downwelling radiation from the cloud strongly affects the cooling rate within the atmosphere and the longwave radiation incident at the surface. Thus, determination of cloud-base temperature is important for proper calculation of fluxes below the cloud. Cloud-base altitude is also an important factor in aircraft operations. Cloud-top height or temperature can be derived in a straightforward manner using satellite-based infrared data. Cloud-base temperature, however, is not observable from the satellite, but is related to the height, phase, and optical depth of the cloud in addition to other variables. This study uses surface and satellite data taken during the First ISCCP Regional Experiment (FIRE) Phase-2 Intensive Field Observation (IFO) period (13 Nov. - 7 Dec. 1991, to improve techniques for deriving cloud-base height from conventional satellite data.

A radiative transfer module for calculating photolysis rates and solar heating in climate models: Solar-J v7.5

NASA Astrophysics Data System (ADS)

Hsu, Juno; Prather, Michael J.; Cameron-Smith, Philip; Veidenbaum, Alex; Nicolau, Alex

2017-07-01

Solar-J is a comprehensive radiative transfer model for the solar spectrum that addresses the needs of both solar heating and photochemistry in Earth system models. Solar-J is a spectral extension of Cloud-J, a standard in many chemical models that calculates photolysis rates in the 0.18-0.8 µm region. The Cloud-J core consists of an eight-stream scattering, plane-parallel radiative transfer solver with corrections for sphericity. Cloud-J uses cloud quadrature to accurately average over correlated cloud layers. It uses the scattering phase function of aerosols and clouds expanded to eighth order and thus avoids isotropic-equivalent approximations prevalent in most solar heating codes. The spectral extension from 0.8 to 12 µm enables calculation of both scattered and absorbed sunlight and thus aerosol direct radiative effects and heating rates throughout the Earth's atmosphere.The Solar-J extension adopts the correlated-k gas absorption bins, primarily water vapor, from the shortwave Rapid Radiative Transfer Model for general circulation model (GCM) applications (RRTMG-SW). Solar-J successfully matches RRTMG-SW's tropospheric heating profile in a clear-sky, aerosol-free, tropical atmosphere. We compare both codes in cloudy atmospheres with a liquid-water stratus cloud and an ice-crystal cirrus cloud. For the stratus cloud, both models use the same physical properties, and we find a systematic low bias of about 3 % in planetary albedo across all solar zenith angles caused by RRTMG-SW's two-stream scattering. Discrepancies with the cirrus cloud using any of RRTMG-SW's three different parameterizations are as large as about 20-40 % depending on the solar zenith angles and occur throughout the atmosphere.Effectively, Solar-J has combined the best components of RRTMG-SW and Cloud-J to build a high-fidelity module for the scattering and absorption of sunlight in the Earth's atmosphere, for which the three major components - wavelength integration, scattering, and averaging over cloud fields - all have comparably small errors. More accurate solutions with Solar-J come with increased computational costs, about 5 times that of RRTMG-SW for a single atmosphere. There are options for reduced costs or computational acceleration that would bring costs down while maintaining improved fidelity and balanced errors.

Atmospheric correction for satellite-based volcanic ash mapping and retrievals using ``split window'' IR data from GOES and AVHRR

NASA Astrophysics Data System (ADS)

Yu, Tianxu; Rose, William I.; Prata, A. J.

2002-08-01

Volcanic ash in volcanic clouds can be mapped in two dimensions using two-band thermal infrared data available from meteorological satellites. Wen and Rose [1994] developed an algorithm that allows retrieval of the effective particle size, the optical depth of the volcanic cloud, and the mass of fine ash in the cloud. Both the mapping and the retrieval scheme are less accurate in the humid tropical atmosphere. In this study we devised and tested a scheme for atmospheric correction of volcanic ash mapping and retrievals. The scheme utilizes infrared (IR) brightness temperature (BT) information in two infrared channels (both between 10 and 12.5 μm) and the brightness temperature differences (BTD) to estimate the amount of BTD shift caused by lower tropospheric water vapor. It is supported by the moderate resolution transmission (MODTRAN) analysis. The discrimination of volcanic clouds in the new scheme also uses both BT and BTD data but corrects for the effects of the water vapor. The new scheme is demonstrated and compared with the old scheme using two well-documented examples: (1) the 18 August 1992 volcanic cloud of Crater Peak, Mount Spurr, Alaska, and (2) the 26 December 1997 volcanic cloud from Soufriere Hills, Montserrat. The Spurr example represents a relatively ``dry'' subarctic atmospheric condition. The new scheme sees a volcanic cloud that is about 50% larger than the old. The mean optical depth and effective radii of cloud particles are lower by 22% and 9%, and the fine ash mass in the cloud is 14% higher. The Montserrat cloud is much smaller than Spurr and is more sensitive to atmospheric moisture. It also was located in a moist tropical atmosphere. For the Montserrat example the new scheme shows larger differences, with the area of the volcanic cloud being about 5.5 times larger, the optical depth and effective radii of particles lower by 56% and 28%, and the total fine particle mass in the cloud increased by 53%. The new scheme can be automated and can contribute to more accurate remote volcanic ash detection. More tests are needed to find the best way to estimate the water vapor effects in real time.

A radiative transfer module for calculating photolysis rates and solar heating in climate models: Solar-J v7.5

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hsu, Juno; Prather, Michael J.; Cameron-Smith, Philip

Solar-J is a comprehensive radiative transfer model for the solar spectrum that addresses the needs of both solar heating and photochemistry in Earth system models. Solar-J is a spectral extension of Cloud-J, a standard in many chemical models that calculates photolysis rates in the 0.18–0.8 µm region. The Cloud-J core consists of an eight-stream scattering, plane-parallel radiative transfer solver with corrections for sphericity. Cloud-J uses cloud quadrature to accurately average over correlated cloud layers. It uses the scattering phase function of aerosols and clouds expanded to eighth order and thus avoids isotropic-equivalent approximations prevalent in most solar heating codes. Themore » spectral extension from 0.8 to 12 µm enables calculation of both scattered and absorbed sunlight and thus aerosol direct radiative effects and heating rates throughout the Earth's atmosphere. Furthermore, the Solar-J extension adopts the correlated-k gas absorption bins, primarily water vapor, from the shortwave Rapid Radiative Transfer Model for general circulation model (GCM) applications (RRTMG-SW). Solar-J successfully matches RRTMG-SW's tropospheric heating profile in a clear-sky, aerosol-free, tropical atmosphere. Here, we compare both codes in cloudy atmospheres with a liquid-water stratus cloud and an ice-crystal cirrus cloud. For the stratus cloud, both models use the same physical properties, and we find a systematic low bias of about 3 % in planetary albedo across all solar zenith angles caused by RRTMG-SW's two-stream scattering. Discrepancies with the cirrus cloud using any of RRTMG-SW's three different parameterizations are as large as about 20–40 % depending on the solar zenith angles and occur throughout the atmosphere. Effectively, Solar-J has combined the best components of RRTMG-SW and Cloud-J to build a high-fidelity module for the scattering and absorption of sunlight in the Earth's atmosphere, for which the three major components – wavelength integration, scattering, and averaging over cloud fields – all have comparably small errors. More accurate solutions with Solar-J come with increased computational costs, about 5 times that of RRTMG-SW for a single atmosphere. There are options for reduced costs or computational acceleration that would bring costs down while maintaining improved fidelity and balanced errors.« less

A radiative transfer module for calculating photolysis rates and solar heating in climate models: Solar-J v7.5

DOE PAGES

Hsu, Juno; Prather, Michael J.; Cameron-Smith, Philip; ...

2017-01-01

Solar-J is a comprehensive radiative transfer model for the solar spectrum that addresses the needs of both solar heating and photochemistry in Earth system models. Solar-J is a spectral extension of Cloud-J, a standard in many chemical models that calculates photolysis rates in the 0.18–0.8 µm region. The Cloud-J core consists of an eight-stream scattering, plane-parallel radiative transfer solver with corrections for sphericity. Cloud-J uses cloud quadrature to accurately average over correlated cloud layers. It uses the scattering phase function of aerosols and clouds expanded to eighth order and thus avoids isotropic-equivalent approximations prevalent in most solar heating codes. Themore » spectral extension from 0.8 to 12 µm enables calculation of both scattered and absorbed sunlight and thus aerosol direct radiative effects and heating rates throughout the Earth's atmosphere. Furthermore, the Solar-J extension adopts the correlated-k gas absorption bins, primarily water vapor, from the shortwave Rapid Radiative Transfer Model for general circulation model (GCM) applications (RRTMG-SW). Solar-J successfully matches RRTMG-SW's tropospheric heating profile in a clear-sky, aerosol-free, tropical atmosphere. Here, we compare both codes in cloudy atmospheres with a liquid-water stratus cloud and an ice-crystal cirrus cloud. For the stratus cloud, both models use the same physical properties, and we find a systematic low bias of about 3 % in planetary albedo across all solar zenith angles caused by RRTMG-SW's two-stream scattering. Discrepancies with the cirrus cloud using any of RRTMG-SW's three different parameterizations are as large as about 20–40 % depending on the solar zenith angles and occur throughout the atmosphere. Effectively, Solar-J has combined the best components of RRTMG-SW and Cloud-J to build a high-fidelity module for the scattering and absorption of sunlight in the Earth's atmosphere, for which the three major components – wavelength integration, scattering, and averaging over cloud fields – all have comparably small errors. More accurate solutions with Solar-J come with increased computational costs, about 5 times that of RRTMG-SW for a single atmosphere. There are options for reduced costs or computational acceleration that would bring costs down while maintaining improved fidelity and balanced errors.« less

Biomass-burning Aerosols in South East-Asia: Smoke Impact Assessment (BASE-ASIA)

NASA Technical Reports Server (NTRS)

Tsay, Si-Chee; Hsu, Christina N.; King, Michael D.; Sun, Wen-Yih

2003-01-01

Biomass burning has been a regular practice for land clearing and land conversion in many countries, especially those in Africa, South America, and Southeast Asia. However, the unique climatology of Southeast Asia is very different than that of Africa and South America, such that large-scale biomass burning causes smoke to interact extensively with clouds during the peak-burning season of March to April. Significant global sources of greenhouse gases (e.g., CO2, CH4), chemically active gases (e.g., NO, CO, HC, CH3Br), and atmospheric aerosols are produced by biomass burning processes. These gases influence the Earth-atmosphere system, impacting both global climate and tropospheric chemistry. Some aerosols can serve as cloud condensation nuclei, which play an important role in determining cloud lifetime and precipitation, hence, altering the earth's radiation and water budget. Biomass burning also affects the biogeochemical cycling of nitrogen and carbon compounds from the soil to the atmosphere; the hydrological cycle (i.e., run off and evaporation); land surface reflectivity and emissivity; as well as ecosystem biodiversity and stability. Analyses from satellite measurements reveal that smoke is frequently present solar (emitted thermal) radiation from clouds due to smoke aerosols can be reduced (enhanced) by as much as 100 (20) W/sq m over the month of March 2000. In addition, the reduction in cloud spectral reflectance at 670 run is large enough to lead to significant errors in retrieving cloud properties (e.g., optical thickness and effective radius) from satellite measurements. The fresh water distribution in this region is highly dependent on monsoon rainfall; in fact, the predictability of the tropical climate system is much reduced during the boreal spring. Estimating the burning fuel (e.g., bark, branches, and wood), an important part of studying regional carbon cycle, may rely on utilizing a wide range of distinctive spectral features in the shortwave and longwave regions. Therefore, to accurately assess the impact of smoke aerosols in this region requires continuous observations from satellites, aircraft, networks of ground-based instruments and dedicated field experiments. A new initiative will be proposed and discussed.

Parameterization and analysis of 3-D radiative transfer in clouds

DOE Office of Scientific and Technical Information (OSTI.GOV)

Varnai, Tamas

2012-03-16

This report provides a summary of major accomplishments from the project. The project examines the impact of radiative interactions between neighboring atmospheric columns, for example clouds scattering extra sunlight toward nearby clear areas. While most current cloud models don't consider these interactions and instead treat sunlight in each atmospheric column separately, the resulting uncertainties have remained unknown. This project has provided the first estimates on the way average solar heating is affected by interactions between nearby columns. These estimates have been obtained by combining several years of cloud observations at three DOE Atmospheric Radiation Measurement (ARM) Climate Research Facility sitesmore » (in Alaska, Oklahoma, and Papua New Guinea) with simulations of solar radiation around the observed clouds. The importance of radiative interactions between atmospheric columns was evaluated by contrasting simulations that included the interactions with those that did not. This study provides lower-bound estimates for radiative interactions: It cannot consider interactions in cross-wind direction, because it uses two-dimensional vertical cross-sections through clouds that were observed by instruments looking straight up as clouds drifted aloft. Data from new DOE scanning radars will allow future radiative studies to consider the full three-dimensional nature of radiative processes. The results reveal that two-dimensional radiative interactions increase overall day-and-night average solar heating by about 0.3, 1.2, and 4.1 Watts per meter square at the three sites, respectively. This increase grows further if one considers that most large-domain cloud simulations have resolutions that cannot specify small-scale cloud variability. For example, the increases in solar heating mentioned above roughly double for a fairly typical model resolution of 1 km. The study also examined the factors that shape radiative interactions between atmospheric columns and found that local effects were often much larger than the overall values mentioned above, and were especially large for high sun and near convective clouds such as cumulus. The study also found that statistical methods such as neural networks appear promising for enabling cloud models to consider radiative interactions between nearby atmospheric columns. Finally, through collaboration with German scientists, the project found that new methods (especially one called stepwise kriging) show great promise in filling gaps between cloud radar scans. If applied to data from the new DOE scanning cloud radars, these methods can yield large, continuous three-dimensional cloud structures for future radiative simulations.« less

A Condensation-coalescence Cloud Model for Exoplanetary Atmospheres: Formulation and Test Applications to Terrestrial and Jovian Clouds

NASA Astrophysics Data System (ADS)

Ohno, Kazumasa; Okuzumi, Satoshi

2017-02-01

A number of transiting exoplanets have featureless transmission spectra that might suggest the presence of clouds at high altitudes. A realistic cloud model is necessary to understand the atmospheric conditions under which such high-altitude clouds can form. In this study, we present a new cloud model that takes into account the microphysics of both condensation and coalescence. Our model provides the vertical profiles of the size and density of cloud and rain particles in an updraft for a given set of physical parameters, including the updraft velocity and the number density of cloud condensation nuclei (CCNs). We test our model by comparing with observations of trade-wind cumuli on Earth and ammonia ice clouds in Jupiter. For trade-wind cumuli, the model including both condensation and coalescence gives predictions that are consistent with observations, while the model including only condensation overestimates the mass density of cloud droplets by up to an order of magnitude. For Jovian ammonia clouds, the condensation-coalescence model simultaneously reproduces the effective particle radius, cloud optical thickness, and cloud geometric thickness inferred from Voyager observations if the updraft velocity and CCN number density are taken to be consistent with the results of moist convection simulations and Galileo probe measurements, respectively. These results suggest that the coalescence of condensate particles is important not only in terrestrial water clouds but also in Jovian ice clouds. Our model will be useful to understand how the dynamics, compositions, and nucleation processes in exoplanetary atmospheres affect the vertical extent and optical thickness of exoplanetary clouds via cloud microphysics.

Overview of the United States Department of Energy's ARM (Atmospheric Radiation Measurement) Program

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stokes, G.M.; Tichler, J.L.

The Department of Energy (DOE) is initiating a major atmospheric research effort, the Atmospheric Radiation Measurement Program (ARM). The program is a key component of DOE's research strategy to address global climate change and is a direct continuation of DOE's decade-long effort to improve the ability of General Circulation Models (GCMs) to provide reliable simulations of regional, and long-term climate change in response to increasing greenhouse gases. The effort is multi-disciplinary and multi-agency, involving universities, private research organizations and more than a dozen government laboratories. The objective of the ARM Research is to provide an experimental testbed for the studymore » of important atmospheric effects, particularly cloud and radiative processes, and to test parameterizations of these processes for use in atmospheric models. This effort will support the continued and rapid improvement of GCM predictive capability. 2 refs.« less

An ensemble constrained variational analysis of atmospheric forcing data and its application to evaluate clouds in CAM5: Ensemble 3DCVA and Its Application

DOE PAGES

Tang, Shuaiqi; Zhang, Minghua; Xie, Shaocheng

2016-01-05

Large-scale atmospheric forcing data can greatly impact the simulations of atmospheric process models including Large Eddy Simulations (LES), Cloud Resolving Models (CRMs) and Single-Column Models (SCMs), and impact the development of physical parameterizations in global climate models. This study describes the development of an ensemble variationally constrained objective analysis of atmospheric large-scale forcing data and its application to evaluate the cloud biases in the Community Atmospheric Model (CAM5). Sensitivities of the variational objective analysis to background data, error covariance matrix and constraint variables are described and used to quantify the uncertainties in the large-scale forcing data. Application of the ensemblemore » forcing in the CAM5 SCM during March 2000 intensive operational period (IOP) at the Southern Great Plains (SGP) of the Atmospheric Radiation Measurement (ARM) program shows systematic biases in the model simulations that cannot be explained by the uncertainty of large-scale forcing data, which points to the deficiencies of physical parameterizations. The SCM is shown to overestimate high clouds and underestimate low clouds. These biases are found to also exist in the global simulation of CAM5 when it is compared with satellite data.« less

An ensemble constrained variational analysis of atmospheric forcing data and its application to evaluate clouds in CAM5: Ensemble 3DCVA and Its Application

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tang, Shuaiqi; Zhang, Minghua; Xie, Shaocheng

Large-scale atmospheric forcing data can greatly impact the simulations of atmospheric process models including Large Eddy Simulations (LES), Cloud Resolving Models (CRMs) and Single-Column Models (SCMs), and impact the development of physical parameterizations in global climate models. This study describes the development of an ensemble variationally constrained objective analysis of atmospheric large-scale forcing data and its application to evaluate the cloud biases in the Community Atmospheric Model (CAM5). Sensitivities of the variational objective analysis to background data, error covariance matrix and constraint variables are described and used to quantify the uncertainties in the large-scale forcing data. Application of the ensemblemore » forcing in the CAM5 SCM during March 2000 intensive operational period (IOP) at the Southern Great Plains (SGP) of the Atmospheric Radiation Measurement (ARM) program shows systematic biases in the model simulations that cannot be explained by the uncertainty of large-scale forcing data, which points to the deficiencies of physical parameterizations. The SCM is shown to overestimate high clouds and underestimate low clouds. These biases are found to also exist in the global simulation of CAM5 when it is compared with satellite data.« less

The Optical Depth Sensor (ODS) for Mars atmosphere

NASA Astrophysics Data System (ADS)

Toledo, D.; Rannou, P.; Pommereau, J.-P.; Sarkissian, A.; Foujols, T.

2013-09-01

A small and sophisticated optical depth sensor (ODS) has been designed to work in the martian atmosphere. The principal goal of ODS is to carry out the opacity due to the Martian dust as well as to characterize the high altitude clouds at twilight, crucial parameters in understanding of Martian meteorology. The instrument was initially designed for the failed MARS96 Russian mission, and also was included in the payload of several other missions [1]. Until recently, it was selected (NASA/ESA AO) in the payload of the atmospheric package DREAMS onboard the MARS 2016 mission. But following a decision of the CNES, it is no more included in the payload. In order to study the performance of ODS under a wide range of conditions as well as its capable to provide daily measurements of both dust optical thickness and high altitude clouds, the instrument has participated in different terrestrial campaigns. A good performance of ODS prototype (Figure 1) on cirrus clouds detection and in dust opacity estimation was previously archived in Africa during 2004-2005 and in Brasil from 2012 to nowadays. Moreover, a campaign in the arctic is expected before 2016 where fifteen ODSs will be part of an integrated observing system over the Arctic Ocean, allowing test the ODS performance in extreme conditions. In this presentation we present main principle of the retrieval, the instrumental concept, the result of the tests performed and the principal objectives of ODS in Mars.

Absorption of Solar Radiation by Clouds: Observations Versus Models

NASA Technical Reports Server (NTRS)

Cess, R. D.; Zhang, M. H.; Minnis, P.; Corsetti, L.; Dutton, E. G.; Forgan, B. W.; Garber, D. P.; Gates, W. L.; Hack, J. J.; Harrison, E. F.;

Outer satellite atmospheres: Their extended nature and planetary interactions. [sodium cloud of Io, hydrogen torus of Titan, and comet atmospheres

NASA Technical Reports Server (NTRS)

Smyth, W. H.

1980-01-01

Highly developed numerical models are applied to interpret extended-atmosphere data for the sodium cloud of Io and the hydrogen torus of Titan. Solar radiation pressure was identified and verified by model calculations as the mechanism to explain two different east-west asymmetries observed in the sodium cloud. Analysis of sodium line profile data, suggesting that a Jupiter magnetospheric wind may be responsible for high speed sodium atoms emitted from Io, and preliminary modeling of the interaction of the Io plasma torus and Io's sodium cloud are also reported. Models presented for Titan's hydrogen torus are consistent both with the recent Pioneer 11 measurements and earlier Earth-orbiting observations by the Copernicus satellite. Progress is reported on developing models for extended gas and dust atmospheres of comets.

Aerosols and their influence on radiation partitioning and savanna productivity in northern Australia

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kanniah, K. D.; Beringer, J.; Tapper, N. J.

2010-05-01

We investigated the effect of aerosols and clouds on the Net Ecosystem Productivity (NEP) of savannas in northern Australia using aerosol optical depth, clouds and radiation data from the Atmospheric Radiation Measurement (ARM) site in Darwin and carbon flux data measured from eddy covariance techniques from a site at Howard Springs, 35km southeast of Darwin. Generally we found that the concentration of aerosols in this region was relatively low than observed at other sites, therefore the proportion of diffuse radiation reaching the earths surface was only ~ 30%. As a result, we observed only a modest change in carbon uptakemore » under aerosol laden skies and there was no significant difference for dry season Radiation Use Efficiency (RUE) between clear sky, aerosols or thin clouds. On the other hand thick clouds in the wet season produce much more diffuse radiation than aerosols or thin clouds and therefore the initial canopy quantum efficiency was seen to increase 45 and 2.5 times more than under thin clouds and aerosols respectively. The normalized carbon uptake under thick clouds is 57% and 50% higher than under aerosols and thin clouds respectively even though the total irradiance received under thick clouds was reduced 59% and 50% than under aerosols and thin clouds respectively. However, reduction in total irradiance decreases the mean absolute carbon uptake as much as 22% under heavy cloud cover compared to thin clouds or aerosols. Thus, any increase in aerosol concentration or cloud cover that can enhance the diffuse component may have large impacts on productivity in this region.« less

Resolving nanoparticle growth mechanisms from size- and time-dependent growth rate analysis

NASA Astrophysics Data System (ADS)

Pichelstorfer, Lukas; Stolzenburg, Dominik; Ortega, John; Karl, Thomas; Kokkola, Harri; Laakso, Anton; Lehtinen, Kari E. J.; Smith, James N.; McMurry, Peter H.; Winkler, Paul M.

2018-01-01

Atmospheric new particle formation occurs frequently in the global atmosphere and may play a crucial role in climate by affecting cloud properties. The relevance of newly formed nanoparticles depends largely on the dynamics governing their initial formation and growth to sizes where they become important for cloud microphysics. One key to the proper understanding of nanoparticle effects on climate is therefore hidden in the growth mechanisms. In this study we have developed and successfully tested two independent methods based on the aerosol general dynamics equation, allowing detailed retrieval of time- and size-dependent nanoparticle growth rates. Both methods were used to analyze particle formation from two different biogenic precursor vapors in controlled chamber experiments. Our results suggest that growth rates below 10 nm show much more variation than is currently thought and pin down the decisive size range of growth at around 5 nm where in-depth studies of physical and chemical particle properties are needed.

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.

Covariance between Arctic sea ice and clouds within atmospheric state regimes at the satellite footprint level

PubMed Central

Kato, Seiji; Xu, Kuan‐Man; Cai, Ming

2015-01-01

Abstract Understanding the cloud response to sea ice change is necessary for modeling Arctic climate. Previous work has primarily addressed this problem from the interannual variability perspective. This paper provides a refined perspective of sea ice‐cloud relationship in the Arctic using a satellite footprint‐level quantification of the covariance between sea ice and Arctic low cloud properties from NASA A‐Train active remote sensing data. The covariances between Arctic low cloud properties and sea ice concentration are quantified by first partitioning each footprint into four atmospheric regimes defined using thresholds of lower tropospheric stability and midtropospheric vertical velocity. Significant regional variability in the cloud properties is found within the atmospheric regimes indicating that the regimes do not completely account for the influence of meteorology. Regional anomalies are used to account for the remaining meteorological influence on clouds. After accounting for meteorological regime and regional influences, a statistically significant but weak covariance between cloud properties and sea ice is found in each season for at least one atmospheric regime. Smaller average cloud fraction and liquid water are found within footprints with more sea ice. The largest‐magnitude cloud‐sea ice covariance occurs between 500 m and 1.2 km when the lower tropospheric stability is between 16 and 24 K. The covariance between low cloud properties and sea ice is found to be largest in fall and is accompanied by significant changes in boundary layer temperature structure where larger average near‐surface static stability is found at larger sea ice concentrations. PMID:27818851

The use of marine cloud water samples as a diagnostic tool for aqueous chemistry, cloud microphysical processes and dynamics

NASA Astrophysics Data System (ADS)

Crosbie, E.; Ziemba, L. D.; Moore, R.; Shook, M.; Jordan, C.; Thornhill, K. L., II; Winstead, E.; Shingler, T.; Brown, M.; MacDonald, A. B.; Dadashazar, H.; Sorooshian, A.; Weiss-Penzias, P. S.; Anderson, B.

2017-12-01

Clouds play several roles in the Earth's climate system. In addition to their clear significance to the hydrological cycle, they strongly modulate the shortwave and longwave radiative balance of the atmosphere, with subsequent feedback on the atmospheric circulation. Furthermore, clouds act as a conduit for the fate and emergence of important trace chemical species and are the predominant removal mechanism for atmospheric aerosols. Marine boundary layer clouds cover large swaths of the global oceans. Because of their global significance, they have attracted significant attention into understanding how changes in aerosols are translated into changes in cloud macro- and microphysical properties. The circular nature of the influence of clouds-on-aerosols and aerosols-on-clouds has been used to explain the chaotic patterns often seen in marine clouds, however, this feedback also presents a substantial hurdle in resolving the uncertain role of anthropogenic aerosols on climate. Here we discuss ways in which the chemical constituents found in cloud water can offer insight into the physical and chemical processes inherent in marine clouds, through the use of aircraft measurements. We focus on observational data from cloud water samples collected during flights conducted over the remote North Atlantic and along coastal California across multiple campaigns. We explore topics related to aqueous processing, wet scavenging and source apportionment.

A Fast Infrared Radiative Transfer Model for Overlapping Clouds

NASA Technical Reports Server (NTRS)

Niu, Jianguo; Yang, Ping; Huang, Huang-Lung; Davies, James E.; Li, Jun; Baum, Bryan A.; Hu, Yong X.

2006-01-01

A fast infrared radiative transfer model (FIRTM2) appropriate for application to both single-layered and overlapping cloud situations is developed for simulating the outgoing infrared spectral radiance at the top of the atmosphere (TOA). In FIRTM2 a pre-computed library of cloud reflectance and transmittance values is employed to account for one or two cloud layers, 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-layered ice or water cloud, and 3) two simultaneous cloud layers in a column (e.g., ice cloud overlying water cloud). Moreover, FIRTM2 outputs the derivatives (i.e., Jacobians) of the TOA brightness temperature with respect to cloud 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-layered clouds are generally less than 0.8 K. For the case of two cloud layers (specifically ice cloud over water cloud), 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) cloud 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.

A Fragment-Cloud Model for Breakup of Asteroids with Varied Internal Structures

NASA Technical Reports Server (NTRS)

Wheeler, Lorien; Mathias, Donovan; Stokan, Ed; Brown, Peter

2016-01-01

As an asteroid descends toward Earth, it deposits energy in the atmosphere through aerodynamic drag and ablation. Asteroid impact risk assessments rely on energy deposition estimates to predict blast overpressures and ground damage that may result from an airburst, such as the one that occurred over Chelyabinsk, Russia in 2013. The rates and altitudes at which energy is deposited along the entry trajectory depend upon how the bolide fragments, which in turn depends upon its internal structure and composition. In this work, we have developed an analytic asteroid fragmentation model to assess the atmospheric energy deposition of asteroids with a range of structures and compositions. The modeling approach combines successive fragmentation of larger independent pieces with aggregate debris clouds released with each fragmentation event. The model can vary the number and masses of fragments produced, the amount of mass released as debris clouds, the size-strength scaling used to increase the robustness of smaller fragments, and other parameters. The initial asteroid body can be seeded with a distribution of independent fragment sizes amid a remaining debris mass to represent loose rubble pile conglomerations, can be given an outer regolith later, or can be defined as a coherent or fractured monolith. This approach enables the model to represent a range of breakup behaviors and reproduce detailed energy deposition features such as multiple flares due to successive burst events, high-altitude regolith blow-off, or initial disruption of rubble piles followed by more energetic breakup of the constituent boulders. These capabilities provide a means to investigate sensitivities of ground damage to potential variations in asteroid structure.

Earth Observation

NASA Image and Video Library

2011-08-02

ISS028-E-020276 (2 Aug. 2011) --- This photograph of polar mesospheric clouds was acquired at an altitude of just over 202 nautical miles (about 322 kilometers) in the evening hours (03:19:54 Greenwich Mean Time) on Aug. 2, 2011, as the International Space Station was passing over the English Channel. The nadir coordinates of the station were 49.1 degrees north latitude and 5.5 degrees west longitude. Polar mesospheric clouds (also known as noctilucent, or ?night-shining? clouds) are transient, upper atmospheric phenomena that are usually observed in the summer months at high latitudes (greater than 50 degrees) of both the Northern and Southern Hemispheres. They appear bright and cloudlike while in deep twilight. They are illuminated by sunlight when the lower layers of the atmosphere are in the darkness of Earth?s shadow. The horizon of Earth appears at the bottom of the image, with some layers of the lower atmosphere already illuminated by the rising sun. The higher, bluish-colored clouds look much like wispy cirrus clouds, which can be found as high as 60,000 feet (18 kilometers) in the atmosphere. However noctilucent clouds, as seen here, are observed in the mesosphere at altitudes of 250,000 to 280,000 feet (about 76 to 85 kilometers). Astronaut observations of polar mesospheric clouds over northern Europe in the summer are not uncommon.

Research concerning the net flux of radiation in the atmosphere of Jupiter

NASA Technical Reports Server (NTRS)

Tomasko, M. G.

1996-01-01

The plan of the NFR (Net Flux of Radiation) team is for the data from the two solar channels (B and E) of NFR to be reduced with the goal of determining the solar heating rate. In order to determine the solar heating rate from the NFR measurements, effects due to the instrument's spatial and spectral response functions, to the temperature variation of the instrument (and associated drift of calibration), to the setting sun, and to the rotation of the probe (initially at a rate comparable to the NFR sampling frequency), all must be well modelled. In the past year, a forward modeling routine was created to simulate NFR data return in the B and E channels. The effects of varying parameters describing the atmospheric model (such as cloud location and thickness) and the descent profile (such as rotation rate) were investigated and an inversion routine was developed. For the forward modeling, existing radiative transfer codes were used to determine intensity fields within the Jovian atmosphere. A routine was developed to determine instantaneous instrument response by integrating the intensity field over the instrument response functions. A second routine was developed to determine the actual output of the NFR by integrating along an arbitrary descent trajectory. Near the top of the atmosphere, the upflux data alone are used to constrain the cloud structure of he atmosphere. To accomplish this, models are used to describe the variation in up flux between consecutive measurements in terms of variations of cloud opacity and variations in known parameters such as the solar zenith angle. This allows us to develop a zero-order model of cloud structure. Lower in the atmosphere, at levels where there is little or no azimuthal structure to the net flux measurements, both the up flux and net flux are used to derive layer transmission and reflection functions, which then determine layer opacity and single scattering albedo. A preliminary analysis of the data began in December 1995. In these data we could see the rapid oscillations expected at the beginning of the data due to probe rotation and the sun passing through the edge of the field of view. In addition, the time when this oscillation stopped was clearly visible. This sets the rough optical depth above the probe at this time.

Using Satellite Data in Weather Forecasting: I

NASA Technical Reports Server (NTRS)

Jedlovec, Gary J.; Suggs, Ronnie J.; Lecue, Juan M.

2006-01-01

The GOES Product Generation System (GPGS) is a set of computer codes and scripts that enable the assimilation of real-time Geostationary Operational Environmental Satellite (GOES) data into regional-weather-forecasting mathematical models. The GPGS can be used to derive such geophysical parameters as land surface temperature, the amount of precipitable water, the degree of cloud cover, the surface albedo, and the amount of insolation from satellite measurements of radiant energy emitted by the Earth and its atmosphere. GPGS incorporates a priori information (initial guesses of thermodynamic parameters of the atmosphere) and radiometric measurements from the geostationary operational environmental satellites along with mathematical models of physical principles that govern the transfer of energy in the atmosphere. GPGS solves the radiative-transfer equation and provides the resulting data products in formats suitable for use by weather-forecasting computer programs. The data-assimilation capability afforded by GPGS offers the potential to improve local weather forecasts ranging from 3 hours to 2 days - especially with respect to temperature, humidity, cloud cover, and the probability of precipitation. The improvements afforded by GPGS could be of interest to news media, utility companies, and other organizations that utilize regional weather forecasts.

Atmospheric Motion in Jupiter Northern Hemisphere

NASA Image and Video Library

2000-09-25

True-color (left) and false-color (right) mosaics of Jupiter's northern hemisphere between 10 and 50 degrees latitude. Jupiter's atmospheric motions are controlled by alternating eastward and westward bands of air between Jupiter's equator and polar regions. The direction and speed of these bands influences the color and texture of the clouds seen in this mosaic. The high and thin clouds are represented by light blue, deep clouds are reddish, and high and thick clouds are white. A high haze overlying a clear, deep atmosphere is represented by dark purple. This image was taken by NASA's Galileo spacecraft on April 3, 1997 at a distance of 1.4 million kilometers (.86 million miles). http://photojournal.jpl.nasa.gov/catalog/PIA03000

An energy balance climate model with cloud feedbacks

NASA Technical Reports Server (NTRS)

Roads, J. O.; Vallis, G. K.

1984-01-01

The present two-level global climate model, which is based on the atmosphere-surface energy balance, includes physically based parameterizations for the exchange of heat and moisture across latitude belts and between the surface and the atmosphere, precipitation and cloud formation, and solar and IR radiation. The model field predictions obtained encompass surface and atmospheric temperature, precipitation, relative humidity, and cloudiness. In the model integrations presented, it is noted that cloudiness is generally constant with changing temperature at low latitudes. High altitude cloudiness increases with temperature, although the cloud feedback effect on the radiation field remains small because of compensating effects on thermal and solar radiation. The net global feedback by the cloud field is negative, but small.

Global Distribution and Vertical Structure of Clouds Revealed by CALIPSO

NASA Astrophysics Data System (ADS)

Yi, Y.; Minnis, P.; Winker, D.; Huang, J.; Sun-Mack, S.; Ayers, K.

2007-12-01

Understanding the effects of clouds on Earth's radiation balance, especially on longwave fluxes within the atmosphere, depends on having accurate knowledge of cloud vertical location within the atmosphere. The Cloud- Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite mission provides the opportunity to measure the vertical distribution of clouds at a greater detail than ever before possible. The CALIPSO cloud layer products from June 2006 to June 2007 are analyzed to determine the occurrence frequency and thickness of clouds as functions of time, latitude, and altitude. In particular, the latitude-longitude and vertical distributions of single- and multi-layer clouds and the latitudinal movement of cloud cover with the changing seasons are examined. The seasonal variablities of cloud frequency and geometric thickness are also analyzed and compared with similar quantities derived from the Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) using the Clouds and the Earth's Radiant Energy System (CERES) cloud retrieval algorithms. The comparisons provide an estimate of the errors in cloud fraction, top height, and thickness incurred by passive algorithms.

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.

Insights from a Regime Decomposition Approach on CERES and CloudSat-inferred Cloud Radiative Effects

NASA Astrophysics Data System (ADS)

Oreopoulos, L.; Cho, N.; Lee, D.

2015-12-01

Our knowledge of the Cloud Radiative Effect (CRE) not only at the Top-of-the-Atmosphere (TOA), but also (with the help of some modeling) at the surface (SFC) and within the atmospheric column (ATM) has been steadily growing in recent years. Not only do we have global values for these CREs, but we can now also plot global maps of their geographical distribution. The next step in our effort to advance our knowledge of CRE is to systematically assess the contributions of prevailing cloud systems to the global values. The presentation addresses this issue directly. We identify the world's prevailing cloud systems, which we call "Cloud Regimes" (CRs) via clustering analysis of MODIS (Aqua-Terra) daily joint histograms of Cloud Top Pressure and Cloud Optical Thickness (TAU) at 1 degree scales. We then composite CERES diurnal values of CRE (TOA, SFC, ATM) separately for each CR by averaging these values for each CR occurrence, and thus find the contribution of each CR to the global value of CRE. But we can do more. We can actually decompose vertical profiles of inferred instantaneous CRE from CloudSat/CALIPSO (2B-FLXHR-LIDAR product) by averaging over Aqua CR occurrences (since A-Train formation flying allows collocation). Such an analysis greatly enhances our understanding of the radiative importance of prevailing cloud mixtures at different atmospheric levels. We can, for example, in addition to examining whether the CERES findings on which CRs contribute to radiative cooling and warming of the atmospheric column are consistent with CloudSat, also gain insight on why and where exactly this happens from the shape of the full instantaneous CRE vertical profiles.

Remote Sensing of Non-Aerosol (anomalous) Absorption in Cloud Free Atmosphere

NASA Technical Reports Server (NTRS)

Kaufman, Yoram J.; Dubovik, Oleg; Smirnov, Alexander; Holben, Brent N.; Lau, William K. M. (Technical Monitor)

2001-01-01

The interaction of sunlight with atmospheric gases, aerosols and clouds is fundamental to the understanding of climate and its variation. Several studies questioned our understanding of atmospheric absorption of sunlight in cloudy or in cloud free atmospheres. Uncertainty in instruments' accuracy and in the analysis methods makes this problem difficult to resolve. Here we use several years of measurements of sky and sun spectral brightness by selected instruments of the Aerosol Robotic Network (AERONET), that have known and high measurement accuracy. The measurements taken in several locations around the world show that in the atmospheric windows 0.44, 0.06, 0.86 and 1.02 microns the only significant absorbers in cloud free atmosphere is aerosol and ozone. This conclusions is reached using a method developed to distinguish between absorption associated with the presence of aerosol and absorption that is not related to the presence of aerosol. Non-aerosol absorption, defined as spectrally independent or smoothly variable, was found to have an optical thickness smaller than 0.002 corresponding to absorption of sunlight less than 1W/sq m, or essentially zero.

ultra-Stable Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research (5STAR)

NASA Astrophysics Data System (ADS)

Dunagan, S. E.; Johnson, R. R.; Redemann, J.; Holben, B. N.; Schmid, B.; Flynn, C. J.; Fahey, L.; LeBlanc, S. E.; Liss, J.; Kacenelenbogen, M. S.; Segal-Rosenhaimer, M.; Shinozuka, Y.; Dahlgren, R. P.; Pistone, K.; Karol, Y.

2017-12-01

The Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research (4STAR) combines airborne sun tracking and sky scanning with diffraction spectroscopy to improve knowledge of atmospheric constituents and their links to air pollution and climate. Direct beam hyperspectral measurement of optical depth improves retrievals of gas constituents and determination of aerosol properties. Sky scanning enhances retrievals of aerosol type and size distribution. Hyperspectral cloud-transmitted radiance measurements enable the retrieval of cloud properties from below clouds. These measurements tighten the closure between satellite and ground-based measurements. 4STAR incorporates a modular sun-tracking/ sky-scanning optical head with optical fiber signal transmission to rack mounted spectrometers, permitting miniaturization of the external optical tracking head, and future detector evolution. 4STAR has supported a broad range of flight experiments since it was first flown in 2010. This experience provides the basis for a series of improvements directed toward reducing measurement uncertainty and calibration complexity, and expanding future measurement capabilities, to be incorporated into a new 5STAR instrument. A 9-channel photodiode radiometer with AERONET-matched bandpass filters will be incorporated to improve calibration stability. A wide dynamic range tracking camera will provide a high precision solar position tracking signal as well as an image of sky conditions around the solar axis. An ultrasonic window cleaning system design will be tested. A UV spectrometer tailored for formaldehyde and SO2 gas retrievals will be added to the spectrometer enclosure. Finally, expansion capability for a 4 channel polarized radiometer to measure the Stokes polarization vector of sky light will be incorporated. This paper presents initial progress on this next-generation 5STAR instrument. Keywords: atmosphere; climate; pollution; radiometry; technology; hyperspectral; fiber optic, polarimetry

Atmospheric Electricity

NASA Astrophysics Data System (ADS)

Aplin, Karen; Fischer, Georg

2018-02-01

Electricity occurs in atmospheres across the Solar System planets and beyond, spanning spectacular lightning displays in clouds of water or dust, to more subtle effects of charge and electric fields. On Earth, lightning is likely to have existed for a long time, based on evidence from fossilized lightning strikes in ancient rocks, but observations of planetary lightning are necessarily much more recent. The generation and observations of lightning and other atmospheric electrical processes, both from within-atmosphere measurements, and spacecraft remote sensing, can be readily studied using a comparative planetology approach, with Earth as a model. All atmospheres contain charged molecules, electrons, and/or molecular clusters created by ionization from cosmic rays and other processes, which may affect an atmosphere's energy balance both through aerosol and cloud formation, and direct absorption of radiation. Several planets are anticipated to host a "global electric circuit" by analogy with the circuit occurring on Earth, where thunderstorms drive current of ions or electrons through weakly conductive parts of the atmosphere. This current flow may further modulate an atmosphere's radiative properties through cloud and aerosol effects. Lightning could potentially have implications for life through its effects on atmospheric chemistry and particle transport. It has been observed on many of the Solar System planets (Earth, Jupiter, Saturn, Uranus, and Neptune) and it may also be present on Venus and Mars. On Earth, Jupiter, and Saturn, lightning is thought to be generated in deep water and ice clouds, but discharges can be generated in dust, as for terrestrial volcanic lightning, and on Mars. Other, less well-understood mechanisms causing discharges in non-water clouds also seem likely. The discovery of thousands of exoplanets has recently led to a range of further exotic possibilities for atmospheric electricity, though lightning detection beyond our Solar System remains a technical challenge to be solved.

Bacteria in atmospheric waters: Detection, characteristics and implications

NASA Astrophysics Data System (ADS)

Hu, Wei; Niu, Hongya; Murata, Kotaro; Wu, Zhijun; Hu, Min; Kojima, Tomoko; Zhang, Daizhou

2018-04-01

In this review paper, we synthesize the current knowledges about bacteria in atmospheric waters, e.g., cloud, fog, rain, and snow, most of which were obtained very recently. First, we briefly describe the importance of bacteria in atmospheric waters, i.e., the essentiality of studying bacteria in atmospheric waters in understanding aerosol-cloud-precipitation-climate interactions in the Earth system. Next, approaches to collect atmospheric water samples for the detection of bacteria and methods to identify the bacteria are summarized and compared. Then the available data on the abundance, viability and community composition of bacteria in atmospheric waters are summarized. The average bacterial concentration in cloud water was usually on the order 104-105 cells mL-1, while that in precipitation on the order 103-104 cells mL-1. Most of the bacteria were viable or metabolically active. Their community composition was highly diverse and differed at various sites. Factors potentially influencing the bacteria, e.g., air pollution levels and sources, meteorological conditions, seasonal effect, and physicochemical properties of atmospheric waters, are described. After that, the implications of bacteria present in atmospheric waters, including their effect on nucleation in clouds, atmospheric chemistry, ecosystems and public health, are briefly discussed. Finally, based on the current knowledges on bacteria in atmospheric waters, which in fact remains largely unknown, we give perspectives that should be paid attention to in future studies.

Antarctic cloud and surface properties: Satellite observations and climate implications

NASA Astrophysics Data System (ADS)

Berque, Joannes

2004-12-01

The radiative effect of clouds in the Antarctic, although small at the top of the atmosphere, is very large within the surface-atmosphere system, and influences a variety of climate processes on a global scale. Because field observations are difficult in the Antarctic interior, satellite observations may be especially valuable in this region; but the remote sensing of clouds and surface properties over the high ice sheets is problematic due to the lack of radiometric contrast between clouds and the snow. A radiative transfer model of the Antarctic snow-atmosphere system is developed, and a new method is proposed for the examination of the problem of cloud properties retrieval from multi-spectral measurements. Key limitations are identified, and a method is developed to overcome them. Using data from the Advanced Very High Resolution Radiometer (AVHRR) onboard National Oceanic and Atmospheric Agency (NOAA) polar orbiters, snow grain size is retrieved over the course of a summer. Significant variability is observed, and it appears related to major precipitation events. A radiative transfer model and a single-column model are used to evaluate the impact of this variability on the Antarctic plateau. The range of observed grain size induces changes of up to 30 Wm-2 on the absorption of shortwave radiation in both models. Cloud properties are then retrieved in summertime imagery of the South Pole. Comparison of model to observations over a wide range of cloud optical depths suggests that this method allows the meaningful interpretation of AVHRR radiances in terms of cloud properties over the Antarctic plateau. The radiative effect of clouds at the top of the atmosphere is evaluated over the South Pole with ground-based lidar observations and data from Clouds and the Earth Radiant Energy System (CERES) onboard NASA's Terra satellite. In accord with previous work, results indicate that the shortwave and net effect are one of cooling throughout the year, while the longwave effect is one of cooling in winter and slight warming in summer.

Infrared Cloud Imager Development for Atmospheric Optical Communication Characterization, and Measurements at the JPL Table Mountain Facility

NASA Astrophysics Data System (ADS)

Nugent, P. W.; Shaw, J. A.; Piazzolla, S.

2013-02-01

The continuous demand for high data return in deep space and near-Earth satellite missions has led NASA and international institutions to consider alternative technologies for high-data-rate communications. One solution is the establishment of wide-bandwidth Earth-space optical communication links, which require (among other things) a nearly obstruction-free atmospheric path. Considering the atmospheric channel, the most common and most apparent impairments on Earth-space optical communication paths arise from clouds. Therefore, the characterization of the statistical behavior of cloud coverage for optical communication ground station candidate sites is of vital importance. In this article, we describe the development and deployment of a ground-based, long-wavelength infrared cloud imaging system able to monitor and characterize the cloud coverage. This system is based on a commercially available camera with a 62-deg diagonal field of view. A novel internal-shutter-based calibration technique allows radiometric calibration of the camera, which operates without a thermoelectric cooler. This cloud imaging system provides continuous day-night cloud detection with constant sensitivity. The cloud imaging system also includes data-processing algorithms that calculate and remove atmospheric emission to isolate cloud signatures, and enable classification of clouds according to their optical attenuation. Measurements of long-wavelength infrared cloud radiance are used to retrieve the optical attenuation (cloud optical depth due to absorption and scattering) in the wavelength range of interest from visible to near-infrared, where the cloud attenuation is quite constant. This article addresses the specifics of the operation, calibration, and data processing of the imaging system that was deployed at the NASA/JPL Table Mountain Facility (TMF) in California. Data are reported from July 2008 to July 2010. These data describe seasonal variability in cloud cover at the TMF site, with cloud amount (percentage of cloudy pixels) peaking at just over 51 percent during February, of which more than 60 percent had optical attenuation exceeding 12 dB at wavelengths in the range from the visible to the near-infrared. The lowest cloud amount was found during August, averaging 19.6 percent, and these clouds were mostly optically thin, with low attenuation.

Clouds and the Earth's Radiant Energy System (CERES) Algorithm Theoretical Basis Document. Volume 3; Cloud Analyses and Determination of Improved Top of Atmosphere Fluxes (Subsystem 4)

NASA Technical Reports Server (NTRS)

1995-01-01

The theoretical bases for the Release 1 algorithms that will be used to process satellite data for investigation of the Clouds and Earth's Radiant Energy System (CERES) are described. The architecture for software implementation of the methodologies is outlined. Volume 3 details the advanced CERES methods for performing scene identification and inverting each CERES scanner radiance to a top-of-the-atmosphere (TOA) flux. CERES determines cloud fraction, height, phase, effective particle size, layering, and thickness from high-resolution, multispectral imager data. CERES derives cloud properties for each pixel of the Tropical Rainfall Measuring Mission (TRMM) visible and infrared scanner and the Earth Observing System (EOS) moderate-resolution imaging spectroradiometer. Cloud properties for each imager pixel are convolved with the CERES footprint point spread function to produce average cloud properties for each CERES scanner radiance. The mean cloud properties are used to determine an angular distribution model (ADM) to convert each CERES radiance to a TOA flux. The TOA fluxes are used in simple parameterization to derive surface radiative fluxes. This state-of-the-art cloud-radiation product will be used to substantially improve our understanding of the complex relationship between clouds and the radiation budget of the Earth-atmosphere system.

Astronomy and Atmospheric Optics

NASA Astrophysics Data System (ADS)

Cowley, Les; Gaina, Alex

2011-12-01

The authors discusse the insuccess of the observation of the Total Eclipse of the Moon from 10 december 2011 in Romania and relate them with meteoconditions. Only a very short part of the last penumbral phase was observed, while the inital part and the totality was not observed due to very dense clouds. The change in color and brightness during this phase was signaled. Meanwhile, there is an area of science where clouds are of great use and interest. This area is Atmospheric optics, while the science which study clouds is meteorology. Clouds in combination with Solar and Moon light could give rise to a variety of strange, rare and unobvious phenomena in the atmosphere (sky), sometimes confused with Unidentified Flying Objects (UFO). The importance of meteorology for astronomy and atmospheric optics is underlined and an invitation to astronomers to use unfavourable days for athmospheric observations was sent. The web address of the site by Les Cowley, designed for atmospheric optics phenomena is contained in the text of the entry.

Retrievals with the Infrared Atmospheric Sounding Interferometer

NASA Technical Reports Server (NTRS)

Zhou, Daniel K.; Liu, Xu; Larar, Allen M.; Smith, William L.; Taylor, Jonathan P.; Schlussel, Peter; Strow, L. Larrabee; Calbet, Xavier; Mango, Stephen A.

2007-01-01

The Infrared Atmospheric Sounding Interferometer (IASI) on the MetOp satellite was launched on October 19, 2006. The Joint Airborne IASI Validation Experiment (JAIVEx) was conducted during April 2007 mainly for validation of the IASI on the MetOp satellite. IASI possesses an ultra-spectral resolution of 0.25/cm and a spectral coverage from 645 to 2760/cm. Ultraspectral resolution infrared spectral radiance obtained from near nadir observations provide atmospheric, surface, and cloud property information. An advanced retrieval algorithm with a fast radiative transfer model, including cloud effects, is used for atmospheric profile and cloud parameter retrieval. Preliminary retrievals of atmospheric soundings, surface properties, and cloud optical/microphysical properties with the IASI observations during the JAIVEx are obtained and presented. These retrievals are further inter-compared with those obtained from airborne FTS system, such as the NPOESS Airborne Sounder Testbed Interferometer (NAST-I), dedicated dropsondes, radiosondes, and ground based Raman Lidar. The capabilities of satellite ultra-spectral sounder such as the IASI are investigated.

Controlled generation of large volumes of atmospheric clouds in a ground-based environmental chamber

NASA Technical Reports Server (NTRS)

Hettel, H. J.; Depena, R. G.; Pena, J. A.

1975-01-01

Atmospheric clouds were generated in a 23,000 cubic meter environmental chamber as the first step in a two part study on the effects of contaminants on cloud formation. The generation procedure was modeled on the terrestrial generation mechanism so that naturally occurring microphysics mechanisms were operative in the cloud generation process. Temperature, altitude, liquid water content, and convective updraft velocity could be selected independently over the range of terrestrially realizable clouds. To provide cloud stability, a cotton muslin cylinder 29.3 meters in diameter and 24.2 meters high was erected within the chamber and continuously wetted with water at precisely the same temperature as the cloud. The improved instrumentation which permitted fast, precise, and continual measurements of cloud temperature and liquid water content is described.

Detecting Super-Thin Clouds With Polarized Light

NASA Technical Reports Server (NTRS)

Sun, Wenbo; Videen, Gorden; Mishchenko, Michael I.

2014-01-01

We report a novel method for detecting cloud particles in the atmosphere. Solar radiation backscattered from clouds is studied with both satellite data and a radiative transfer model. A distinct feature is found in the angle of linear polarization of solar radiation that is backscattered from clouds. The dominant backscattered electric field from the clear-sky Earth-atmosphere system is nearly parallel to the Earth surface. However, when clouds are present, this electric field can rotate significantly away from the parallel direction. Model results demonstrate that this polarization feature can be used to detect super-thin cirrus clouds having an optical depth of only 0.06 and super-thin liquid water clouds having an optical depth of only 0.01. Such clouds are too thin to be sensed using any current passive satellite instruments.

Detecting Super-Thin Clouds with Polarized Sunlight

NASA Technical Reports Server (NTRS)

Sun, Wenbo; Videen, Gorden; Mishchenko, Michael I.

2014-01-01

We report a novel method for detecting cloud particles in the atmosphere. Solar radiation backscattered from clouds is studied with both satellite data and a radiative transfer model. A distinct feature is found in the angle of linear polarization of solar radiation that is backscattered from clouds. The dominant backscattered electric field from the clear-sky Earth-atmosphere system is nearly parallel to the Earth surface. However, when clouds are present, this electric field can rotate significantly away from the parallel direction. Model results demonstrate that this polarization feature can be used to detect super-thin cirrus clouds having an optical depth of only 0.06 and super-thin liquid water clouds having an optical depth of only 0.01. Such clouds are too thin to be sensed using any current passive satellite instruments.

Characterizing synoptic and cloud variability in the northern atlantic using self-organizing maps

NASA Astrophysics Data System (ADS)

Fish, Carly

Low-level clouds have a significant influence on the Earth's radiation budget and it is thus imperative to understand their behavior within the marine boundary layer (MBL). The cloud properties in the Northeast Atlantic region are highly variable in space and time and are a research focus for many atmospheric scientists. Characterizing the synoptic patterns in the region through the implementation of self-organizing maps (SOMs) enables a climatological grasp of cloud and atmospheric fields. ERA -- Interim and MODIS provide the platform to explore the variability in the Northeast Atlantic for over 30 years of data. Station data comes from CAP -- MBL on Graciosa Island in the Azores, which lies in a strong gradient of cloud and other atmospheric fields, offer an opportunity to incorporate an observational aspect for the years of 2009 and 2010.

Net thermal radiation in the atmosphere of Venus

NASA Technical Reports Server (NTRS)

Revercomb, H. E.; Sromovsky, L. A.; Suomi, V. E.; Boese, R. W.

1985-01-01

Estimates of the true atmospheric net fluxes at the four Pioneer Venus entry sites are presently obtained through corrections of measured values that are relatively small for the case of the clouds, but generally large deeper in the atmosphere. The correction procedure for both the small and large probe fluxes used model results near 14 km to establish the size of the correction. The thermal net fluxes obtained imply that the contribution of mode 3 particles to the IR opacity of the middle and lower clouds is smaller than indicated by the Pioneer Venus cloud particle spectrometer measurements, and the day probe results favor a reduction of only about 50 percent. The fluxes at all sites imply that a yet-undetermined source of considerable opacity is present in the upper cloud. Beneath the clouds, the thermal net fluxes generally increase with increasing latitude.

Role of Microphysical Parameterizations with Droplet Relative Dispersion in IAP AGCM 4.1

DOE PAGES

Xie, Xiaoning; Zhang, He; Liu, Xiaodong; ...

2018-01-10

In previous studies we see that accurate descriptions of the cloud droplet effective radius (Re) and the autoconversion process of cloud droplets to raindrops (Au) can effectively improve simulated clouds and surface precipitation, and reduce the uncertainty of aerosol indirect effects in global climate models (GCMs). In this paper, we implement cloud microphysical schemes including two-moment Au and R e considering relative dispersion of the cloud droplet size distribution into version 4.1 of the Institute of Atmospheric Physics atmospheric GCM (IAP AGCM 4.1), which is the atmospheric component of the Chinese Academy of Sciences-Earth System model (CAS-ESM 1.0). An analysismore » of the effects of different schemes shows that the newly implemented schemes can improve both the simulated shortwave (SWCF) and longwave cloud radiative forcings (LWCF) as compared to the standard scheme in IAP AGCM 4.1. The new schemes also effectively enhance the large-scale precipitation, especially over low latitudes, although the influences of total precipitation are insignificant for different schemes. Further studies show that similar results can be found with the Community Atmosphere Model 5.1 (CAM5.1).« less

Role of Microphysical Parameterizations with Droplet Relative Dispersion in IAP AGCM 4.1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xie, Xiaoning; Zhang, He; Liu, Xiaodong

In previous studies we see that accurate descriptions of the cloud droplet effective radius (Re) and the autoconversion process of cloud droplets to raindrops (Au) can effectively improve simulated clouds and surface precipitation, and reduce the uncertainty of aerosol indirect effects in global climate models (GCMs). In this paper, we implement cloud microphysical schemes including two-moment Au and R e considering relative dispersion of the cloud droplet size distribution into version 4.1 of the Institute of Atmospheric Physics atmospheric GCM (IAP AGCM 4.1), which is the atmospheric component of the Chinese Academy of Sciences-Earth System model (CAS-ESM 1.0). An analysismore » of the effects of different schemes shows that the newly implemented schemes can improve both the simulated shortwave (SWCF) and longwave cloud radiative forcings (LWCF) as compared to the standard scheme in IAP AGCM 4.1. The new schemes also effectively enhance the large-scale precipitation, especially over low latitudes, although the influences of total precipitation are insignificant for different schemes. Further studies show that similar results can be found with the Community Atmosphere Model 5.1 (CAM5.1).« less

The Atmospheric Channels of GLAS: Near Real-Time Global Lidar Remote Sensing of Clouds and Aerosols from Space

NASA Technical Reports Server (NTRS)

Palm, Stephen P.; Hlavka, Dennis; Hart, Bill; Welton, E. Judd; Spinhirne, James

2000-01-01

The Geoscience Laser Altimeter System (GLAS) will be placed into orbit in 2001 aboard the Ice, Cloud and Land Elevation Satellite (ICESat). From its nearly polar orbit (94 degree inclination), GLAS will provide continuous global measurements of the vertical distribution of clouds and aerosols while simultaneously providing high accuracy topographic profiling of surface features. During the mission, which is slated to last 3 to 5 years, the data collected by GLAS will be in near-real time to produce level 1 and 2 data products at the NASA GLAS Science Computing Facility (SCF) at Goddard Space Flight Center in Greenbelt, Maryland. The atmospheric products include cloud and aerosol layer heights, planetary boundary layer depth, polar stratospheric clouds and thin cloud and aerosol optical depth. These products will be made available to the science community within days of their creation. The processing algorithms must be robust, adaptive, efficient, and clever enough to run autonomously for the widely varying atmospheric conditions that will be encountered. This paper presents an overview of the GLAS atmospheric data products and briefly discusses the design of the processing algorithms.

Explicit prediction of ice clouds in general circulation models

NASA Astrophysics Data System (ADS)

Kohler, Martin

1999-11-01

Although clouds play extremely important roles in the radiation budget and hydrological cycle of the Earth, there are large quantitative uncertainties in our understanding of their generation, maintenance and decay mechanisms, representing major obstacles in the development of reliable prognostic cloud water schemes for General Circulation Models (GCMs). Recognizing their relative neglect in the past, both observationally and theoretically, this work places special focus on ice clouds. A recent version of the UCLA - University of Utah Cloud Resolving Model (CRM) that includes interactive radiation is used to perform idealized experiments to study ice cloud maintenance and decay mechanisms under various conditions in term of: (1) background static stability, (2) background relative humidity, (3) rate of cloud ice addition over a fixed initial time-period and (4) radiation: daytime, nighttime and no-radiation. Radiation is found to have major effects on the life-time of layer-clouds. Optically thick ice clouds decay significantly slower than expected from pure microphysical crystal fall-out (taucld = 0.9--1.4 h as opposed to no-motion taumicro = 0.5--0.7 h). This is explained by the upward turbulent fluxes of water induced by IR destabilization, which partially balance the downward transport of water by snowfall. Solar radiation further slows the ice-water decay by destruction of the inversion above cloud-top and the resulting upward transport of water. Optically thin ice clouds, on the other hand, may exhibit even longer life-times (>1 day) in the presence of radiational cooling. The resulting saturation mixing ratio reduction provides for a constant cloud ice source. These CRM results are used to develop a prognostic cloud water scheme for the UCLA-GCM. The framework is based on the bulk water phase model of Ose (1993). The model predicts cloud liquid water and cloud ice separately, and which is extended to split the ice phase into suspended cloud ice (predicted) and falling snow (diagnosed) components. An empirical parameterization of the effect of upward turbulent water fluxes in cloud layers is obtained from the CRM simulations by (1) identifying the time-scale of conversion of cloud ice to snow as the key parameter, and (2) regressing it onto cloud differential IR heating and environmental static stability. The updated UCLA-GCM achieves close agreement with observations in global mean top of atmosphere fluxes (within 1--4 W/m2). Artificially suppressing the impact of cloud turbulent fluxes reduces the global mean ice water path by a factor of 3 and produces errors in each of solar and IR fluxes at the top of atmosphere of about 5--6 W/m2.

Characterization of the cloud conditions at Ny-Ålesund using sensor synergy and representativeness of the observed clouds across Arctic sites

NASA Astrophysics Data System (ADS)

Nomokonova, Tatiana; Ebell, Kerstin; Löhnert, Ulrich; Maturilli, Marion

2017-04-01

Clouds are one of the crucial components of the hydrological and energy cycles and thus affecting the global climate. Their special importance in Arctic regions is defined by cloud's influence on the radiation budget. Arctic clouds usually occur at low altitudes and often contain highly concentrated tiny liquid drops. During winter, spring, and autumn periods such clouds tend to conserve the long-wave radiation in the atmosphere and, thus, produce warming of the Arctic climate. In summer though clouds efficiently scatter the solar radiation back to space and, therefore, induce a cooling effect. An accurate characterization of the net effect of clouds on the Arctic climate requires long-term and precise observations. However, only a few measurement sites exist which perform continuous, vertically resolved observations of clouds in the Arctic, e.g. in Alaska, Canada, and Greenland. These sites typically make use of a combination of different ground-based remote sensing instruments, e.g. cloud radar, ceilometer and microwave radiometer in order to characterize clouds. Within the Transregional Collaborative Research Center (TR 172) "Arctic Amplification: Climate Relevant Atmospheric and Surface Processes, and Feedback Mechanisms (AC)3" comprehensive observations of the atmospheric column are performed at the German-French Research Station AWIPEV at Ny-Ålesund, Svalbard. Ny-Ålesund is located in the warmest part of the Arctic where climate is significantly influenced by adiabatic heating from the warm ocean. Thus, measurements at Ny-Ålesund will complement our understanding of cloud formation and development in the Arctic. This particular study is devoted to the characterization of the cloud macro- and microphysical properties at Ny-Ålesund and of the atmospheric conditions, under which these clouds form and develop. To this end, the information of the various instrumentation at the AWIPEV observatory is synergistically analysed: information about the thermodynamic structure of the atmosphere is obtained from long-term radiosonde launches. In addition, continuous vertical profiles of temperature and humidity are provided by the microwave radiometer HATPRO. A set of active remote sensing instruments performs cloud observations at Ny-Ålesund: a ceilometer and a Doppler lidar operating since 2011 and 2013, respectively, are now complemented with a novel 94 GHz FMCW cloud radar. As a first step, the CLOUDNET algorithms, including a target categorization and classification, are applied to the observations. In this study, we will present a first analysis of cloud properties at Ny-Ålesund including for example cloud occurrence, cloud geometry (cloud base, cloud top, and thickness) and cloud type (liquid, ice, mixed-phase). The different types of clouds are set into context to the environmental conditions such as temperature, amount of water vapour, and liquid water. We also expect that the cloud properties strongly depend on the wind direction. The first results of this analysis will be also shown.

Air Force Global Weather Central System Architecture Study. Final System/Subsystem Summary Report. Volume 4. Systems Analysis and Trade Studies

DTIC Science & Technology

1976-03-01

atmosphere,as well as very fine grid cloud models and cloud probability models. Some of the new requirements that will be supported with this system are a...including the Advanced Prediction Model for the global atmosphere, as well as very fine grid cloud models and cloud proba- bility models. Some of the new...with the mapping and gridding function (imput and output)? Should the capability exist to interface raw ungridded data with the SID interface

NH4SH and cloud cover in the atmospheres of the giant planets

NASA Astrophysics Data System (ADS)

Ibragimov, K. Iu.; Solodovnik, A. A.

1991-02-01

The probability of the formation of NH4SH and (NH4)2S is examined on the basis of the Le Chatelier principle. It is shown that it is very doubtful if NH4SH can be created in the atmospheres of the giant planets in quantities sufficient for cloud formation. Thus (NH4)2S is considered as a more likely candidate for cloud formation in the atmospheres of these planets, inasmuch as the conditions for its production there are more favorable.

A Diagnostic PDF Cloud Scheme to Improve Subtropical Low Clouds in NCAR Community Atmosphere Model (CAM5)

NASA Astrophysics Data System (ADS)

Qin, Yi; Lin, Yanluan; Xu, Shiming; Ma, Hsi-Yen; Xie, Shaocheng

2018-02-01

Low clouds strongly impact the radiation budget of the climate system, but their simulation in most GCMs has remained a challenge, especially over the subtropical stratocumulus region. Assuming a Gaussian distribution for the subgrid-scale total water and liquid water potential temperature, a new statistical cloud scheme is proposed and tested in NCAR Community Atmospheric Model version 5 (CAM5). The subgrid-scale variance is diagnosed from the turbulent and shallow convective processes in CAM5. The approach is able to maintain the consistency between cloud fraction and cloud condensate and thus alleviates the adjustment needed in the default relative humidity-based cloud fraction scheme. Short-term forecast simulations indicate that low cloud fraction and liquid water content, including their diurnal cycle, are improved due to a proper consideration of subgrid-scale variance over the southeastern Pacific Ocean region. Compared with the default cloud scheme, the new approach produced the mean climate reasonably well with improved shortwave cloud forcing (SWCF) due to more reasonable low cloud fraction and liquid water path over regions with predominant low clouds. Meanwhile, the SWCF bias over the tropical land regions is also alleviated. Furthermore, the simulated marine boundary layer clouds with the new approach extend further offshore and agree better with observations. The new approach is able to obtain the top of atmosphere (TOA) radiation balance with a slightly alleviated double ITCZ problem in preliminary coupled simulations. This study implies that a close coupling of cloud processes with other subgrid-scale physical processes is a promising approach to improve cloud simulations.

A-Train Observations of Young Volcanic Eruption Clouds

NASA Astrophysics Data System (ADS)

Carn, S. A.; Prata, F.; Yang, K.; Rose, W. I.

2011-12-01

NASA's A-Train satellite constellation (including Aqua, CloudSat, CALIPSO, and Aura) has been flying in formation since 2006, providing unprecedented synergistic observations of numerous volcanic eruption clouds in various stages of development. Measurements made by A-Train sensors include total column SO2 by the Ozone Monitoring Instrument (OMI) on Aura, upper tropospheric and stratospheric (UTLS) SO2 column by the Atmospheric Infrared Sounder (AIRS) on Aqua and Microwave Limb Sounder (MLS) on Aura, ash mass loading from AIRS and the Moderate resolution Imaging Spectroradiometer (MODIS) on Aqua, UTLS HCl columns and ice water content (IWC) from MLS, aerosol vertical profiles from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) instrument aboard CALIPSO, and hydrometeor profiles from the Cloud Profiling Radar (CPR) on CloudSat. The active vertical profiling capability of CALIPSO, CloudSat and MLS sychronized with synoptic passive sensing of trace gases and aerosols by OMI, AIRS and MODIS provides a unique perspective on the structure and composition of volcanic clouds. A-Train observations during the first hours of atmospheric residence are particularly valuable, as the fallout, segregation and stratification of material in this period determines the concentration and altitude of constituents that remain to be advected downwind. This represents the eruption 'source term' essential for dispersion modeling, and hence for aviation hazard mitigation. In this presentation we show examples of A-Train data collected during recent eruptions including Chaitén (May 2008), Kasatochi (August 2008), Redoubt (March 2009), Eyjafjallajökull (April 2010) and Cordón Caulle (June 2011). We interpret the observations using the canonical three-stage view of volcanic cloud development [e.g., Rose et al., 2000] from initial rapid ash fallout to far-field dispersion of fine ash, gas and aerosol, and results from numerical modeling of volcanic plumes [e.g., Textor et al., 2003] and discuss the degree to which the observations validate existing theory and models. We also describe plans for advanced SO2 and ash retrieval algorithms that will exploit the synergy between UV and IR sensors in the A-Train for improved quantification of ash and SO2 loading by volcanic eruptions.

A new laboratory facility to study the interactions of aerosols, cloud droplets/ice crystals, and trace gases in a turbulent environment: The Π Chamber

NASA Astrophysics Data System (ADS)

Cantrell, W. H., II; Chang, K.; Ciochetto, D.; Niedermeier, D.; Bench, J.; Shaw, R. A.

2014-12-01

A detailed understanding of gas-aerosol-cloud interaction within the turbulent atmosphere is of prime importance for an accurate understanding of Earth's climate system. As one example: While every cloud droplet began as an aerosol particle, not every aerosol particle becomes a cloud droplet. The particle to droplet transformation requires that the particle be exposed to some critical concentration of water vapor, which differs for different combinations of particle size and chemical composition. Similarly, the formation of ice particles in mixed phase clouds is also catalyzed by aerosol particles. Even in the simplest scenarios it is challenging to gain a full understanding of the aerosol activation and ice nucleation processes. At least two other factors contribute significantly to the complexity observed in the atmosphere. First, aerosols and cloud particles are not static entities, but are continuously interacting with their chemical environment, and therefore changing in their properties. Second, clouds are ubiquitously turbulent, so thermodynamic and compositional variables, such as water vapor or other trace gas concentrations, fluctuate in space and time. Indeed, the coupling between turbulence and microphysical processes is one of the major research challenges in cloud physics. We have developed a multiphase, turbulent reaction chamber, (dubbed the Π Chamber, after the internal volume of 3.14 cubic meters) designed to address the problems outlined above. It is capable of pressures ranging from sea level to ~ 100 mbar, and can sustain temperatures of +40 to -55 ºC. We can independently control the temperatures on the surfaces of three heat transfer zones. This allows us to establish a temperature gradient between the floor and ceiling inducing Rayleigh-Benard convection and inducing a turbulent environment. Interior surfaces are electropolished stainless steel to facilitate cleaning before and after chemistry experiments. At present, supporting instrumentation includes a suite of aerosol generation and characterization techniques, a laser Doppler interferometer, and a holographic cloud particle imaging system.We will present detailed specifications, an overview of the supporting instrumentation, and initial characterization experiments from the Π chamber.

Cloud characterization and clear-sky correction from Landsat-7

USGS Publications Warehouse

Cahalan, Robert F.; Oreopoulos, L.; Wen, G.; Marshak, S.; Tsay, S. -C.; DeFelice, Tom

2001-01-01

Landsat, with its wide swath and high resolution, fills an important mesoscale gap between atmospheric variations seen on a few kilometer scale by local surface instrumentation and the global view of coarser resolution satellites such as MODIS. In this important scale range, Landsat reveals radiative effects on the few hundred-meter scale of common photon mean-free-paths, typical of scattering in clouds at conservative (visible) wavelengths, and even shorter mean-free-paths of absorptive (near-infrared) wavelengths. Landsat also reveals shadowing effects caused by both cloud and vegetation that impact both cloudy and clear-sky radiances. As a result, Landsat has been useful in development of new cloud retrieval methods and new aerosol and surface retrievals that account for photon diffusion and shadowing effects. This paper discusses two new cloud retrieval methods: the nonlocal independent pixel approximation (NIPA) and the normalized difference nadir radiance method (NDNR). We illustrate the improvements in cloud property retrieval enabled by the new low gain settings of Landsat-7 and difficulties found at high gains. Then, we review the recently developed “path radiance” method of aerosol retrieval and clear-sky correction using data from the Department of Energy Atmospheric Radiation Measurement (ARM) site in Oklahoma. Nearby clouds change the solar radiation incident on the surface and atmosphere due to indirect illumination from cloud sides. As a result, if clouds are nearby, this extra side-illumination causes clear pixels to appear brighter, which can be mistaken for extra aerosol or higher surface albedo. Thus, cloud properties must be known in order to derive accurate aerosol and surface properties. A three-dimensional (3D) Monte Carlo (MC) radiative transfer simulation illustrates this point and suggests a method to subtract the cloud effect from aerosol and surface retrievals. The main conclusion is that cloud, aerosol, and surface retrievals are linked and must be treated as a combined system. Landsat provides the range of scales necessary to observe the 3D cloud radiative effects that influence joint surface-atmospheric retrievals.

Polarization of Hazes and Aurorae on Jupiter

NASA Astrophysics Data System (ADS)

Yanamandra-Fisher, Padma A.; McLean, Will; PACA_Jupiter

2017-10-01

Our solar system planets show a large variety of atmospheric polarization properties, from the thick, highly polarizing haze on Titan and the poles of Jupiter, Rayleigh scattering by molecules on Uranus and Neptune, to clouds in the equatorial region of Jupiter or on Venus. Changes in the clouds/thermal filed can be brought about by endogenic dynamical processes such merger of vortices; global, planetary scale upheavals, and external factors such as celestial collisions (such as D/Shoemaker-Levy 9 impact with Jupiter in 1994, etc.). Although the range of phase angles available from Earth for outer planets is restricted to a narrow range, limb polarization measurements provide constraints on the polarimetric properties. For example, at the equator, much of the observed reflected radiation is due to the presence of clouds and therefore, low polarization. Polar asymmetry exists between the two poles, while the planetary disk is unpolarized. Jupiter is known to exhibit a strong polar limb polarization and a low equatorial limb polarization due to the presence of haze particles and Rayleigh scattering at the poles. In contrast, at the equator, the concentration of particulates in the high atmosphere might change, changing the polarimetric signature and aurorae at both poles. The polarimetric maps, in conjunction with thermal maps and albedo maps, can provide constraints on modeling efforts to understand the nature of the aerosols/hazes in Jovian atmosphere. With Jupiter experiencing morphological changes at many latitudes, we have initiated a polarimetric observing campaign of Jupiter, in conjunction with The PACA Project. With NASA/Juno mission in a 53-day orbit around Jupiter, and recent outbreaks in the atmosphere, changes in the polarimetric signature will provide insight to the changes occurring in the atmosphere. Some of our observations are acquired by a team of professional/amateur planetary imagers astronomers based in the U.K., Australia and Europe. France. Details/results of these studies will be presented to optimize the observing strategy of planetary atmospheres and their role in the atmospheric retrievals and the next stage of polarimetric exploration of Jupiter.

A Numerical Study of Convection in a Condensing CO2 Atmosphere under Early Mars-Like Conditions

NASA Astrophysics Data System (ADS)

Nakajima, Kensuke; Yamashita, Tatsuya; Odaka, Masatsugu; Sugiyama, Ko-ichiro; Ishiwatari, Masaki; Nishizawa, Seiya; Takahashi, Yoshiyuki O.; Hayashi, Yoshi-Yuki

2017-10-01

Cloud convection of a CO2 atmosphere where the major constituent condenses is numerically investigated under a setup idealizing a possible warm atmosphere of early Mars, utilizing a two-dimensional cloud-resolving model forced by a fixed cooling profile as a substitute for a radiative process. The authors compare two cases with different critical saturation ratios as condensation criteria and also examine sensitivity to number mixing ratio of condensed particles given externally.When supersaturation is not necessary for condensation, the entire horizontal domain above the condensation level is continuously covered by clouds irrespective of number mixing ratio of condensed particles. Horizontal-mean cloud mass density decreases exponentially with height. The circulations below and above the condensation level are dominated by dry cellular convection and buoyancy waves, respectively.When 1.35 is adopted as the critical saturation ratio, clouds appear exclusively as intense, short-lived, quasi-periodic events. Clouds start just above the condensation level and develop upward, but intense updrafts exist only around the cloud top; they do not extend to the bottom of the condensation layer. The cloud layer is rapidly warmed by latent heat during the cloud events, and then the layer is slowly cooled by the specified thermal forcing, and supersaturation gradually develops leading to the next cloud event. The periodic appearance of cloud events does not occur when number mixing ratio of condensed particles is large.

Evaluating and improving cloud phase in the Community Atmosphere Model version 5 using spaceborne lidar observations

NASA Astrophysics Data System (ADS)

Kay, Jennifer E.; Bourdages, Line; Miller, Nathaniel B.; Morrison, Ariel; Yettella, Vineel; Chepfer, Helene; Eaton, Brian

2016-04-01

Spaceborne lidar observations from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite are used to evaluate cloud amount and cloud phase in the Community Atmosphere Model version 5 (CAM5), the atmospheric component of a widely used state-of-the-art global coupled climate model (Community Earth System Model). By embedding a lidar simulator within CAM5, the idiosyncrasies of spaceborne lidar cloud detection and phase assignment are replicated. As a result, this study makes scale-aware and definition-aware comparisons between model-simulated and observed cloud amount and cloud phase. In the global mean, CAM5 has insufficient liquid cloud and excessive ice cloud when compared to CALIPSO observations. Over the ice-covered Arctic Ocean, CAM5 has insufficient liquid cloud in all seasons. Having important implications for projections of future sea level rise, a liquid cloud deficit contributes to a cold bias of 2-3°C for summer daily maximum near-surface air temperatures at Summit, Greenland. Over the midlatitude storm tracks, CAM5 has excessive ice cloud and insufficient liquid cloud. Storm track cloud phase biases in CAM5 maximize over the Southern Ocean, which also has larger-than-observed seasonal variations in cloud phase. Physical parameter modifications reduce the Southern Ocean cloud phase and shortwave radiation biases in CAM5 and illustrate the power of the CALIPSO observations as an observational constraint. The results also highlight the importance of using a regime-based, as opposed to a geographic-based, model evaluation approach. More generally, the results demonstrate the importance and value of simulator-enabled comparisons of cloud phase in models used for future climate projection.

A Condensation–coalescence Cloud Model for Exoplanetary Atmospheres: Formulation and Test Applications to Terrestrial and Jovian Clouds

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ohno, Kazumasa; Okuzumi, Satoshi

A number of transiting exoplanets have featureless transmission spectra that might suggest the presence of clouds at high altitudes. A realistic cloud model is necessary to understand the atmospheric conditions under which such high-altitude clouds can form. In this study, we present a new cloud model that takes into account the microphysics of both condensation and coalescence. Our model provides the vertical profiles of the size and density of cloud and rain particles in an updraft for a given set of physical parameters, including the updraft velocity and the number density of cloud condensation nuclei (CCNs). We test our modelmore » by comparing with observations of trade-wind cumuli on Earth and ammonia ice clouds in Jupiter. For trade-wind cumuli, the model including both condensation and coalescence gives predictions that are consistent with observations, while the model including only condensation overestimates the mass density of cloud droplets by up to an order of magnitude. For Jovian ammonia clouds, the condensation–coalescence model simultaneously reproduces the effective particle radius, cloud optical thickness, and cloud geometric thickness inferred from Voyager observations if the updraft velocity and CCN number density are taken to be consistent with the results of moist convection simulations and Galileo probe measurements, respectively. These results suggest that the coalescence of condensate particles is important not only in terrestrial water clouds but also in Jovian ice clouds. Our model will be useful to understand how the dynamics, compositions, and nucleation processes in exoplanetary atmospheres affect the vertical extent and optical thickness of exoplanetary clouds via cloud microphysics.« less

Using Satellite Observations to Evaluate the AeroCOM Volcanic Emissions Inventory and the Dispersal of Volcanic SO2 Clouds in MERRA

NASA Technical Reports Server (NTRS)

Hughes, Eric J.; Krotkov, Nickolay; da Silva, Arlindo; Colarco, Peter

2015-01-01

Simulation of volcanic emissions in climate models requires information that describes the eruption of the emissions into the atmosphere. While the total amount of gases and aerosols released from a volcanic eruption can be readily estimated from satellite observations, information about the source parameters, like injection altitude, eruption time and duration, is often not directly known. The AeroCOM volcanic emissions inventory provides estimates of eruption source parameters and has been used to initialize volcanic emissions in reanalysis projects, like MERRA. The AeroCOM volcanic emission inventory provides an eruptions daily SO2 flux and plume top altitude, yet an eruption can be very short lived, lasting only a few hours, and emit clouds at multiple altitudes. Case studies comparing the satellite observed dispersal of volcanic SO2 clouds to simulations in MERRA have shown mixed results. Some cases show good agreement with observations Okmok (2008), while for other eruptions the observed initial SO2 mass is half of that in the simulations, Sierra Negra (2005). In other cases, the initial SO2 amount agrees with the observations but shows very different dispersal rates, Soufriere Hills (2006). In the aviation hazards community, deriving accurate source terms is crucial for monitoring and short-term forecasting (24-h) of volcanic clouds. Back trajectory methods have been developed which use satellite observations and transport models to estimate the injection altitude, eruption time, and eruption duration of observed volcanic clouds. These methods can provide eruption timing estimates on a 2-hour temporal resolution and estimate the altitude and depth of a volcanic cloud. To better understand the differences between MERRA simulations and volcanic SO2 observations, back trajectory methods are used to estimate the source term parameters for a few volcanic eruptions and compared to their corresponding entry in the AeroCOM volcanic emission inventory. The nature of these mixed results is discussed with respect to the source term estimates.

Spectroscopic Observation of Chemical Interaction Between Impact-induced Vapor Clouds and the Ambient Atmosphere

NASA Technical Reports Server (NTRS)

Sugita, S.; Heineck, J. T.; Schultz, P. H.

2000-01-01

Chemical reactions within impact-induced vapor clouds were observed in laboratory experiments using a spectroscopic method. The results indicate that projectile-derived carbon-rich vapor reacts intensively with atmospheric nitrogen.

An efficient routine for infrared radiative transfer in a cloudy atmosphere

NASA Technical Reports Server (NTRS)

Chou, M. D.; Kouvaris, L.

1981-01-01

A FORTRAN program that calculates the atmospheric cooling rate and infrared fluxes for partly cloudy atmospheres is documented. The IR fluxes in the water bands and the 9.6 and 15 micron bands are calculated at 15 levels ranging from 1.39 mb to the surface. The program is generalized to accept any arbitrary atmospheric temperature and humidity profiles and clouds as input and return the cooling rate and fluxes as output. Sample calculations for various atmospheric profiles and cloud situations are demonstrated.

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 factor of 3 due to interactions between the excessive LW radiative cooling and extra cloud water; heating caused by phase change of hydrometeors could affect the LWC and cloud top height by partially canceling out the LW radiative cooling. It is further shown that the resolved dynamical circulation appears to contribute more greatly to the evolution of the MPS cloud layers than the parameterized subgrid-scale circulation.

Investigation of the radiative forcings of thin cirrus in the tropical atmosphere using remote sensing data

NASA Astrophysics Data System (ADS)

Yue, Qing

Cirrus clouds have a unique influence on the climate system through their effects on the radiation budget of the earth and the atmosphere. To better understand the radiative effect of cirrus clouds, the microphysical and radiative properties of these clouds, especially tropical thin cirrus clouds, are studied based on both insitu cirrus measurements and satellite remote sensing observations. We perform a correlation analysis involving ice water content (IWC) and mean effective diameter (De) for applications to radiative transfer calculations and climate models using insitu measurements obtained from numerous field campaigns in the tropics, midlatitude, and Arctic regions. In conjunction with the study of cirrus clouds, we develop a high-resolution spectral infrared radiative transfer model for thin cirrus cloudy atmosphere, which is employed to retrieve De and cirrus optical depth from the Atmospheric Infrared Sounder (AIRS) infrared spectra. Numerical simulations show that cirrus cloudy radiances in the 800-1130 cm-1 thermal infrared window are sufficiently sensitive to variations in cirrus optical depth, and ice crystal size and habit. A number of nighttime thin cirrus scenes over the Atmospheric Radiation Measurement (ARM) program's Tropical Western Pacific sites have been selected from AIRS datasets for this study. The radiative transfer model is applied to these selected cases to determine cirrus optical depth, De and habit factors. Solar and infrared radiative forcings and heating rates produced by thin cirrus in the tropical atmosphere have been calculated using the retrieved cirrus optical and microphysical properties along with a modified Fu and Liou broadband radiative transfer scheme to analyze their dependence on cirrus cloud properties. Generally, larger TOA warming and smaller surface warming are associated with higher cirrus clouds. To cross-check the validity of our model, the collocated and coincident surface radiation measurements taken by ARM pyrgeometers have been compared with the calculated surface fluxes. Using the method developed in this study, regional radiation budget analyses can be carried out in the future study to quantitatively understand the role of thin cirrus clouds on solar and thermal infrared radiative forcings at the top of the atmosphere, the tropopause, and the surface.

Ambient in-situ immersion freezing measurements - findings from the ZAMBIS 2014 field campaign for three ice nucleation techniques

NASA Astrophysics Data System (ADS)

Kohn, Monika; Atkinson, James D.; Lohmann, Ulrike; Kanji, Zamin A.

2015-04-01

To estimate the influence of clouds on the Earth's radiation budget, it is crucial to understand cloud formation processes in the atmosphere. A key process, which significantly affects cloud microphysical properties and the initiation of precipitation thus contributing to the hydrological cycle, is the prevailing type of ice nucleation mechanism. In mixed-phase clouds immersion freezing is the dominant ice crystal forming mechanism, whereby ice nucleating particles (INP) first act as cloud condensation nuclei (CCN) and are activated to cloud droplets followed by freezing upon supercooling. There are a number of experimental methods and techniques to investigate the ice nucleating ability in the immersion mode, however most techniques are offline for field sampling or only suitable for laboratory measurements. In-situ atmospheric studies are needed to understand the ice formation processes of 'real world' particles. Laboratory experiments simulate conditions of atmospheric processes like ageing or coating but are still idealized. Our method is able to measure ambient in-situ immersion freezing on single immersed aerosol particles. The instrumental setup consists of the recently developed portable immersion mode cooling chamber (PIMCA) as a vertical extension to the portable ice nucleation chamber (PINC, [1]), where the frozen fraction of activated aerosol particles are detected by the ice optical depolarization detector (IODE, [2]). Two additional immersion freezing techniques based on a droplet freezing array [3,4] are used to sample ambient aerosol particles either in a suspension (fraction larger ~0.6 μm) or on PM10-filters to compare different ice nucleation techniques. Here, we present ambient in-situ measurements at an urban forest site in Zurich, Switzerland held during the Zurich ambient immersion freezing study (ZAMBIS) in spring 2014. We investigated the ice nucleating ability of natural atmospheric aerosol with the PIMCA/PINC immersion freezing setup as well as a droplet freezing method on aerosol particles either collected in a suspension or on PM10-filters to obtain atmospheric IN concentrations based on the measured ambient aerosol. Investigation of physical properties (number and size distribution) and chemical composition as well as the meteorological conditions provide supplementary information that help to understand the nature of particles and air masses that contribute to immersion freezing. Acknowledgements We thank Hannes Wydler and Hansjörg Frei from ETH Zurich for their technical support. Furthermore, the authors want thank Franz Conen from the University of Basel for sharing equipment and training in the drop freezing experiment. References [1] Chou et al. (2011), Atmos. Chem. Phys., 11, 4725-4738. [2] Nicolet et al. (2010), Atmos. Chem. Phys., 10, 313-325. [3] Conen et al. (2012), Atmos. Meas. Tech., 5, 321-327. [4] Stopelli et al. (2014), Atmos. Meas. Tech., 7, 129-134.

Is microbiolgy an alternative route to photochemistry in atmospheric chemistry?

NASA Astrophysics Data System (ADS)

Vaitilingom, M.; Parazols, M.; Sancelme, M.; Deguillaume, L.; Mailhot, G.; Delort, A.-M.

2009-04-01

Until very recently scientists from atmospheric sciences focussed their studies on physical and chemical phenomena taking place in cloud water phase neglecting the presence of active microorganisms in this medium. For instance, considering atmospheric chemistry, solar light is considered as the predominant catalyser for chemical reactions occurring in the atmosphere. However recent studies show that living and active microorganisms, including bacteria, yeasts and fungi, are present in the atmospheric water phase and could play an active role in chemistry of clouds. Indeed living microorganisms are clearly biocatalysts which could transform organic compounds as an alternative route to photochemistry. The objective of our project is to bring answers to this new scientific question by a multidisciplinary approach involving atmospheric physicists, photochemists and microbiologists. Microorganisms have been isolated and identified in cloud water sampled at the puy de Dôme summit which is an atmospheric observatory and a European referenced site. Laboratory experiments were carried out to evaluate the potential of organic species (carboxylic acids) degradation by the photochemical or microbiological ways. The project was centred on few carboxylic acids among them succinic, acetic, formic and oxalic acids (the most important organic acids in cloud water sampled at Puy de Dôme). Degradation rates were measured during biodegradation alone (Pseudomonas syringae), photochemistry alone (hydrogen peroxide + light) and combing both processed using artificial reconstituted cloud water. Our first results show that the obtained degradation rates are in the range of order.

Atmospheric science on the Galileo mission

NASA Technical Reports Server (NTRS)

Hunten, D. M.; Colin, L.; Hansen, J. E.

1986-01-01

The atmospheric science goals of the Galileo mission, and instruments of the probe and orbiter are described. The current data available, and the goals of the Galileo mission concerning the chemical composition of the Jovian atmosphere; the thermal structure of the atmosphere; the nature of cloud particles and cloud layering; the radiative energy balance; atmospheric dynamics; and the upper atmosphere are discussed. The objectives and operations of the atmospheric structure instrument, neutral mass spectrometer, helium abundance interferometer, nephelometer, net flux radiometer, lightning and radio emission detector, solid state imaging system, NIR mapping spectrometer, photopolarimeter radiometer, and UV spectrometer are examined.

Model of the vertical structure of the optical parameters of the Neptune atmosphere.

NASA Astrophysics Data System (ADS)

Morozhenko, A. V.

Analyzes the wavelength dependence of the geometric albedo of Neptune's disk and estimates some parameters of the planet's atmosphere by the method based on the determination of deviations of the vertical structure of the cloud layer from the homogeneity condition. The ratio between the methane and gas scale heights is found to be about 0.4. For the upper atmosphere, components of methane, aerosol, the mean geometric radius of particles, the turbulent mixing coefficient are determined. Two solutions were found for deeper atmospheric layers. The first one suggests a rather dense cloud; in the second solution the lower cloud layer is an extension of the upper aerosol layer.

The NASA-Goddard Multi-Scale Modeling Framework - Land Information System: Global Land/atmosphere Interaction with Resolved Convection

NASA Technical Reports Server (NTRS)

Mohr, Karen Irene; Tao, Wei-Kuo; Chern, Jiun-Dar; Kumar, Sujay V.; Peters-Lidard, Christa D.

2013-01-01

The present generation of general circulation models (GCM) use parameterized cumulus schemes and run at hydrostatic grid resolutions. To improve the representation of cloud-scale moist processes and landeatmosphere interactions, a global, Multi-scale Modeling Framework (MMF) coupled to the Land Information System (LIS) has been developed at NASA-Goddard Space Flight Center. The MMFeLIS has three components, a finite-volume (fv) GCM (Goddard Earth Observing System Ver. 4, GEOS-4), a 2D cloud-resolving model (Goddard Cumulus Ensemble, GCE), and the LIS, representing the large-scale atmospheric circulation, cloud processes, and land surface processes, respectively. The non-hydrostatic GCE model replaces the single-column cumulus parameterization of fvGCM. The model grid is composed of an array of fvGCM gridcells each with a series of embedded GCE models. A horizontal coupling strategy, GCE4fvGCM4Coupler4LIS, offered significant computational efficiency, with the scalability and I/O capabilities of LIS permitting landeatmosphere interactions at cloud-scale. Global simulations of 2007e2008 and comparisons to observations and reanalysis products were conducted. Using two different versions of the same land surface model but the same initial conditions, divergence in regional, synoptic-scale surface pressure patterns emerged within two weeks. The sensitivity of largescale circulations to land surface model physics revealed significant functional value to using a scalable, multi-model land surface modeling system in global weather and climate prediction.

NARVAL North - Remote Sensing of Postfrontal Convective Clouds and Precipitation over the North Atlantic with the Research Aircraft HALO

NASA Astrophysics Data System (ADS)

Klepp, Christian; Ament, Felix; Bakan, Stephan; Crewell, Susanne; Hagen, Martin; Hirsch, Lutz; Jansen, Friedhelm; Konow, Heike; Mech, Mario; Pfeilsticker, Klaus; Schäfler, Andreas; Stevens, Bjorn

2014-05-01

The new German research aircraft HALO (High Altitude and Long Range Research Aircraft) became recently available for measurement flights in atmospheric research. It's capacity of measuring from a high altitude vertical profiles of all components of atmospheric water - like vapor, liquid and ice, in both cloud and precipitation forms, as well as the aerosol particles upon which cloud droplets form - makes it a unique research platform. The aircraft, equipped with advanced radiometers, radar and lidar technology, the HALO Microwave Package (HAMP), is an initiative by German climate and environmental research institutions and is operated by the German Aerospace Center (DLR). One of the first major missions to exploit the capabilities of HALO was conducted for the NARVAL project (Next-generation Aircraft Remote-Sensing for Validation Studies) during January 2014. After studying subtropical clouds one month before in the first NARVAL phase, the interest of NARVAL North focused on the study of cold air convection and precipitation in the form of rain and snow. Based at Keflavik airport (Iceland), several flights were conducted to examine the specific small-scale precipitation structures behind the backsides of cold fronts over the North Atlantic. This should help to narrow the gap in the understanding of substantial differences between satellite observations and model calculations in such situations. First data analysis of these measurements indicate promising results. The poster will describe the HALO instrument packages as well as the collected observations during the campaign and will present preliminary scientific findings.

The Diurnal Cycle in TOGA-COARE: Regional Scale Model Simulations

NASA Technical Reports Server (NTRS)

Tao, W.-K.; Jia, Y.

1999-01-01

The diurnal variation of precipitation processes over the tropics is a well-known phenomenon and has been studied using surface rainfall data, radar reflectivity data, and satellite-derived cloudiness and precipitation. Recently, analyzed observations from Tropical Oceans and Global Atmosphere Coupled Ocean-Atmosphere Response Experiment (TOGA COARE) in the tropical western Pacific ocean to study the relevant mechanisms producing diurnal variation of precipitation. They found that the diurnal Sea surface temperature (SST) cycle is important for afternoon showers in the undisturbed periods and diurnal radiative processes for nocturnal rainfall. Cloud resolving models (CRMS) have been used to determine the mechanisms associated with diurnal variation of precipitating processes. CRMs allow explicit cloud-radiation and air-sea interactive processes. However, CRMs can be only used for idealized simulations (i.e., no feedback between clouds and their embedded large-scale environments; cyclic lateral boundary conditions and idealized initial conditions). In this study, the Penn State/NCAR Mesoscale Model (MM5) with improved physics (i.e., cloud microphysics, radiation, land-soil-vegetation-surface processes, and TOGA COARE flux scheme) and a multiple level nesting technique (covers the TOGA COARE LSA/IFA with a 54 km grid and can nest down to 18, 6 and possibly even 2 km) will be adopted for studying the diurnal variations of rainfall. We will examine precipitation processes over open ocean and over land. We will also perform sensitivity tests to determine how the radiative forcing and diurnal SST cycle affects the development of convection.

Image velocimetry for clouds with relaxation labeling based on deformation consistency

NASA Astrophysics Data System (ADS)

Horinouchi, Takeshi; Murakami, Shin-ya; Kouyama, Toru; Ogohara, Kazunori; Yamazaki, Atsushi; Yamada, Manabu; Watanabe, Shigeto

2017-08-01

Correlation-based cloud tracking has been extensively used to measure atmospheric winds, but still difficulty remains. In this study, aiming at developing a cloud tracking system for Akatsuki, an artificial satellite orbiting Venus, a formulation is developed for improving the relaxation labeling technique to select appropriate peaks of cross-correlation surfaces which tend to have multiple peaks. The formulation makes an explicit use of consistency inherent in the type of cross-correlation method where template sub-images are slid without deformation; if the resultant motion vectors indicate a too-large deformation, it is contradictory to the assumption of the method. The deformation consistency is exploited further to develop two post processes; one clusters the motion vectors into groups within each of which the consistency is perfect, and the other extends the groups using the original candidate lists. These processes are useful to eliminate erroneous vectors, distinguish motion vectors at different altitudes, and detect phase velocities of waves in fluids such as atmospheric gravity waves. As a basis of the relaxation labeling and the post processes as well as uncertainty estimation, the necessity to find isolated (well-separated) peaks of cross-correlation surfaces is argued, and an algorithm to realize it is presented. All the methods are implemented, and their effectiveness is demonstrated with initial images obtained by the ultraviolet imager onboard Akatsuki. Since the deformation consistency regards the logical consistency inherent in template matching methods, it should have broad application beyond cloud tracking.

Optical Depth Sensor (ODS) for the measurement of dust and clouds properties in the Mars atmosphere

NASA Astrophysics Data System (ADS)

Toledo, D.; Rannou, P.; Pommereau, J.-P.; Sarkissian, A.; Foujols, T.

2014-04-01

A small and sophisticated optical depth sensor (ODS) has been designed to work in both Martian and Earth environments. The principal goal of ODS is to carry out the opacity due to the Martian dust as well as to characterize the high altitude clouds at twilight, crucial parameters in understanding of Martian meteorology. The instrument was initially designed for the failed MARS96 Russian mission, and also was included in the payload of several other missions [1]. Until recently, it was selected (NASA/ESA AO) in the payload of the atmospheric package DREAMS onboard the MARS 2016 mission. But following a decision of the CNES, it is no more included in the payload. In order to study the performance of ODS under a wide range of conditions as well as its capable to provide daily measurements of both dust optical thickness and high altitude clouds properties, the instrument has participated in different terrestrial campaigns. A good performance of ODS prototype (Figure 1) on cirrus clouds detection and in dust opacity estimation was previously archived in Africa during 2004-2005 and in Brasil from 2012 to nowadays. Moreover, a campaign in the arctic is expected before 2016 where fifteen ODSs will be part of an integrated observing system over the Arctic Ocean, allowing test the ODS performance in extreme conditions. In this presentation we present main principle of the retrieval, the instrumental concept, the result of the tests performed and the principal objectives of ODS in Mars.

EDITORIAL: Focus on Cloud Physics FOCUS ON CLOUD PHYSICS

NASA Astrophysics Data System (ADS)

Falkovich, Gregory; Malinowski, Szymon P.

2008-07-01

Cloud physics has for a long time been an important segment of atmospheric science. It is common knowledge that clouds are crucial for our understanding of weather and climate. Clouds are also interesting by themselves (not to mention that they are beautiful). Complexity is hidden behind the common picture of these beautiful and interesting objects. The typical school textbook definition that a cloud is 'a set of droplets or particles suspended in the atmosphere' is not adequate. Clouds are complicated phenomena in which dynamics, turbulence, microphysics, thermodynamics and radiative transfer interact on a wide range of scales, from sub-micron to kilometres. Some of these interactions are subtle and others are more straightforward. Large and small-scale motions lead to activation of cloud condensation nuclei, condensational growth and collisions; small changes in composition and concentration of atmospheric aerosol lead to significant differences in radiative properties of the clouds and influence rainfall formation. It is justified to look at a cloud as a composite, nonlinear system which involves many interactions and feedback. This system is actively linked into a web of atmospheric, oceanic and even cosmic interactions. Due to the complexity of the cloud system, present-day descriptions of clouds suffer from simplifications, inadequate parameterizations, and omissions. Sometimes the most fundamental physics hidden behind these simplifications and parameterizations is not known, and a wide scope of view can sometimes prevent a 'microscopic', deep insight into the detail. Only the expertise offered by scientists focused on particular elementary processes involved in this complicated pattern of interactions allows us to shape elements of the puzzle from which a general picture of clouds can be created. To be useful, every element of the puzzle must be shaped precisely. This often creates problems in communication between the sciences responsible for shaping elements of the puzzle, and those which combine them. Scales, assumptions and the conditions used in order to describe a particular single process of interest must be consistent with the conditions in clouds. The papers in this focus issue of New Journal of Physics collectively demonstrate (i) the variation in scientific approaches towards investigating cloud processes, (ii) the various stages of shaping elements of the puzzle, and (iii) some attempts to put the pieces together. These papers present just a small subset of loosely arranged elements in an initial stage of puzzle creation. Addressed by this issue is one of the important problems in our understanding of cloud processes—the interaction between cloud particles and turbulence. There is currently a gap between the cloud physics community and scientists working in wind tunnels, on turbulence theory and particle interactions. This collection is intended to narrow this gap by bringing together work by theoreticians, modelers, laboratory experimentalists and those who measure and observe actual processes in clouds. It forms a collage of contributions showing various approaches to cloud processes including: • theoretical works with possible applications to clouds (Bistagnino and Boffetta, Gustavsson et al), • an attempt to construct a phenomenological description of clouds and rain (Lovejoy and Schertzer), • simplified models designed to parameterize turbulence micro- and macro-effects (Celani et al, Derevyanko et al), • focused theoretical research aimed at particular cloud processes (Ayala et al, parts I and II, Wang et al), • laboratory and modeling studies of complex cloud processes (Malinowski et al). This collage is far from being complete but, hopefully, should give the reader a representative impression of the current state of knowledge in the field. We hope it will be useful to all scientists whose work is inspired by cloud processes. Focus on Cloud Physics Contents The equivalent size of cloud condensation nuclei Antonio Celani, Andrea Mazzino and Marco Tizzi Laboratory and modeling studies of cloud-clear air interfacial mixing: anisotropy of small-scale turbulence due to evaporative cooling Szymon P Malinowski, Miroslaw Andrejczuk, Wojciech W Grabowski, Piotr Korczyk, Tomasz A Kowalewski and Piotr K Smolarkiewicz Evolution of non-uniformly seeded warm clouds in idealized turbulent conditions Stanislav Derevyanko, Gregory Falkovich and Sergei Turitsyn Lagrangian statistics in two-dimensional free turbulent convection A Bistagnino and G Boffetta Turbulence, raindrops and the l1/2 number density law S Lovejoy and D Schertzer Effects of turbulence on the geometric collision rate of sedimenting droplets. Part 2. Theory and parameterization Orlando Ayala, Bogdan Rosa and Lian-Ping Wang Effects of turbulence on the geometric collision rate of sedimenting droplets. Part 1. Results from direct numerical simulation Orlando Ayala, Bogdan Rosa, Lian-Ping Wang and Wojciech W Grabowski Collisions of particles advected in random flows K Gustavsson, B Mehlig and M Wilkinson Turbulent collision efficiency of heavy particles relevant to cloud droplets Lian-Ping Wang, Orlando Ayala, Bogdan Rosa and Wojciech W Grabowski

A Bispectral Composite Threshold Approach for Automatic Cloud Detection in VIIRS Imagery

NASA Technical Reports Server (NTRS)

LaFontaine Frank J.; Jedlovec, Gary J.

2015-01-01

The detection of clouds in satellite imagery has a number of important applications in weather and climate studies. The presence of clouds can alter the energy budget of the Earth-atmosphere system through scattering and absorption of shortwave radiation and the absorption and re-emission of infrared radiation at longer wavelengths. The scattering and absorption characteristics of clouds vary with the microphysical properties of clouds, hence the cloud type. Thus, detecting the presence of clouds over a region in satellite imagery is important in order to derive atmospheric or surface parameters that give insight into weather and climate processes. For many applications however, clouds are a contaminant whose presence interferes with retrieving atmosphere or surface information. In these cases, is important to isolate cloud-free pixels, used to retrieve atmospheric thermodynamic information or surface geophysical parameters, from cloudy ones. This abstract describes an application of a two-channel bispectral composite threshold (BCT) approach applied to VIIRS imagery. The simplified BCT approach uses only the 10.76 and 3.75 micrometer spectral channels from VIIRS in two spectral tests; a straight-forward infrared threshold test with the longwave channel and a shortwave - longwave channel difference test. The key to the success of this approach as demonstrated in past applications to GOES and MODIS data is the generation of temporally and spatially dependent thresholds used in the tests from a previous number of days at similar observations to the current data. The paper and subsequent presentation will present an overview of the approach and intercomparison results with other satellites, methods, and against verification data.

Measurement of optical blurring in a turbulent cloud chamber

NASA Astrophysics Data System (ADS)

Packard, Corey D.; Ciochetto, David S.; Cantrell, Will H.; Roggemann, Michael C.; Shaw, Raymond A.

2016-10-01

Earth's atmosphere can significantly impact the propagation of electromagnetic radiation, degrading the performance of imaging systems. Deleterious effects of the atmosphere include turbulence, absorption and scattering by particulates. Turbulence leads to blurring, while absorption attenuates the energy that reaches imaging sensors. The optical properties of aerosols and clouds also impact radiation propagation via scattering, resulting in decorrelation from unscattered light. Models have been proposed for calculating a point spread function (PSF) for aerosol scattering, providing a method for simulating the contrast and spatial detail expected when imaging through atmospheres with significant aerosol optical depth. However, these synthetic images and their predicating theory would benefit from comparison with measurements in a controlled environment. Recently, Michigan Technological University (MTU) has designed a novel laboratory cloud chamber. This multiphase, turbulent "Pi Chamber" is capable of pressures down to 100 hPa and temperatures from -55 to +55°C. Additionally, humidity and aerosol concentrations are controllable. These boundary conditions can be combined to form and sustain clouds in an instrumented laboratory setting for measuring the impact of clouds on radiation propagation. This paper describes an experiment to generate mixing and expansion clouds in supersaturated conditions with salt aerosols, and an example of measured imagery viewed through the generated cloud is shown. Aerosol and cloud droplet distributions measured during the experiment are used to predict scattering PSF and MTF curves, and a methodology for validating existing theory is detailed. Measured atmospheric inputs will be used to simulate aerosol-induced image degradation for comparison with measured imagery taken through actual cloud conditions. The aerosol MTF will be experimentally calculated and compared to theoretical expressions. The key result of this study is the proposal of a closure experiment for verification of theoretical aerosol effects using actual clouds in a controlled laboratory setting.

Autonomous, Full-Time Cloud Profiling at Arm Sites with Micro Pulse Lidar

NASA Technical Reports Server (NTRS)

Spinhirne, James D.; Campbell, James R.; Hlavka, Dennis L.; Scott, V. Stanley; Flynn, Connor J.

2000-01-01

Since the early 1990's technology advances permit ground based lidar to operate full time and profile all significant aerosol and cloud structure of the atmosphere up to the limit of signal attenuation. These systems are known as Micro Pulse Lidars (MPL), as referenced by Spinhirne (1993), and were first in operation at DOE Atmospheric Radiation Measurement (ARM) sites. The objective of the ARM program is to improve the predictability of climate change, particularly as it relates to cloud-climate feedback. The fundamental application of the MPL systems is towards the detection of all significant hydrometeor layers, to the limit of signal attenuation. The heating and cooling of the atmosphere are effected by the distribution and characteristics of clouds and aerosol concentration. Aerosol and cloud retrievals in several important areas can only be adequately obtained with active remote sensing by lidar. For cloud cover, the height and related emissivity of thin clouds and the distribution of base height for all clouds are basic parameters for the surface radiation budget, and lidar is essetial for accurate measurements. The ARM MPL observing network represents the first long-term, global lidar study known within the community. MPL systems are now operational at four ARM sites. A six year data set has been obtained at the original Oklahoma site, and there are several years of observations at tropical and artic sites. Observational results include cloud base height distributions and aerosol profiles. These expanding data sets offer a significant new resource for cloud, aerosol and atmospheric radiation analysis. The nature of the data sets, data processing algorithms, derived parameters and application results are presented.

Measurement of Atmospheric CO2 Column Concentrations to Cloud Tops With a Pulsed Multi-Wavelength Airborne Lidar

NASA Technical Reports Server (NTRS)

Mao, Jianping; Ramanathan, Anand; Abshire, James B.; Kawa, Stephan R.; Riris, Haris; Allan, Graham R.; Rodriguez, Michael R.; Hasselbrack, William E.; Sun, Xiaoli; Numata, Kenji;

Measurement of atmospheric CO2 column concentrations to cloud tops with a pulsed multi-wavelength airborne lidar

NASA Astrophysics Data System (ADS)

Mao, Jianping; Ramanathan, Anand; Abshire, James B.; Kawa, Stephan R.; Riris, Haris; Allan, Graham R.; Rodriguez, Michael; Hasselbrack, William E.; Sun, Xiaoli; Numata, Kenji; Chen, Jeff; Choi, Yonghoon; Yang, Mei Ying Melissa

2018-01-01

We have measured the column-averaged atmospheric CO2 mixing ratio to a variety of cloud tops by using an airborne pulsed multi-wavelength integrated-path differential absorption (IPDA) lidar. Airborne measurements were made at altitudes up to 13 km during the 2011, 2013 and 2014 NASA Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) science campaigns flown in the United States West and Midwest and were compared to those from an in situ sensor. Analysis of the lidar backscatter profiles shows the average cloud top reflectance was ˜ 5 % for the CO2 measurement at 1572.335 nm except to cirrus clouds, which had lower reflectance. The energies for 1 µs wide laser pulses reflected from cloud tops were sufficient to allow clear identification of CO2 absorption line shape and then to allow retrievals of atmospheric column CO2 from the aircraft to cloud tops more than 90 % of the time. Retrievals from the CO2 measurements to cloud tops had minimal bias but larger standard deviations when compared to those made to the ground, depending on cloud top roughness and reflectance. The measurements show this new capability helps resolve CO2 horizontal and vertical gradients in the atmosphere. When used with nearby full-column measurements to ground, the CO2 measurements to cloud tops can be used to estimate the partial-column CO2 concentration below clouds, which should lead to better estimates of surface carbon sources and sinks. This additional capability of the range-resolved CO2 IPDA lidar technique provides a new benefit for studying the carbon cycle in future airborne and space-based CO2 missions.

ARC-1990-AC91-2005

NASA Image and Video Library

1990-02-10

Range : 60,000 miles This image is a false-color version of a near- infrared map of lower-level clouds on the night side of Venus, obtained by the Near Infrared Mapping Spectrometer aboard Galileo. Taken 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 middle atmosphere some 30-33 miles above the surface, 6-10 miles below the visible cloudtops. The image shows the radiant heat from the lower atmosphere (about 400 degrees F) shining through the sulfuric acid clouds, which appear as much as 10 times darker than the bright gaps between clouds. The colors indicate relative cloud transparency; white and red show thin cloud regions, while black and blue represent relatively this clouds. This cloud layer is at about 170 degrees F., 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 clouds visible at top and bottom left. 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. The Near Infrared Mapping Spectrometer (NIMS) on the Galileo 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 spectroscopic-ally analyze atmospheres and surfaces and construct thermal and chemical maps. Designed and operated by scientists and engineers at the JPL, NIMS involves 15 scientists in the US, England and France.

Cloud-top height retrieval from polarizing remote sensor POLDER

NASA Astrophysics Data System (ADS)

He, Xianqiang; Pan, Delu; Yan, Bai; Mao, Zhihua

2006-10-01

A new cloud-top height retrieval method is proposed by using polarizing remote sensing. In cloudy conditions, it shows that, in purple and blue bands, linear polarizing radiance at the top-of-atmosphere (TOA) is mainly contributed by Rayleigh scattering of the atmosphere's molecules above cloud, and the contribution by cloud reflection and aerosol scattering can be neglected. With such characteristics, the basis principle and method of cloud-top height retrieval using polarizing remote sensing are presented in detail, and tested by the polarizing remote sensing data of POLDER. The satellite-derived cloud-top height product can not only show the distribution of global cloud-top height, but also obtain the cloud-top height distribution of moderate-scale meteorological phenomena like hurricanes and typhoons. This new method is promising to become the operational algorithm for cloud-top height retrieval for POLDER and the future polarizing remote sensing satellites.

Microphysical Modeling of Mineral Clouds in GJ1214 b and GJ436 b: Predicting Upper Limits on the Cloud-top Height

NASA Astrophysics Data System (ADS)

Ohno, Kazumasa; Okuzumi, Satoshi

2018-05-01

The ubiquity of clouds in the atmospheres of exoplanets, especially of super-Earths, is one of the outstanding issues for the transmission spectra survey. Understanding the formation process of clouds in super-Earths is necessary to interpret the observed spectra correctly. In this study, we investigate the vertical distributions of particle size and mass density of mineral clouds in super-Earths using a microphysical model that takes into account the vertical transport and growth of cloud particles in a self-consistent manner. We demonstrate that the vertical profiles of mineral clouds significantly vary with the concentration of cloud condensation nuclei and atmospheric metallicity. We find that the height of the cloud top increases with increasing metallicity as long as the metallicity is lower than the threshold. If the metallicity is larger than the threshold, the cloud-top height no longer increases appreciably with metallicity because coalescence yields larger particles of higher settling velocities. We apply our cloud model to GJ1214 b and GJ436 b, for which recent transmission observations suggest the presence of high-altitude opaque clouds. For GJ436 b, we show that KCl particles can ascend high enough to explain the observation. For GJ1214 b, by contrast, the height of KCl clouds predicted from our model is too low to explain its flat transmission spectrum. Clouds made of highly porous KCl particles could explain the observations if the atmosphere is highly metal-rich, and hence the particle microstructure might be a key to interpret the flat spectrum of GJ1214 b.

Atmospheric CO2 Concentration Measurements with Clouds from an Airborne Lidar

NASA Astrophysics Data System (ADS)

Mao, J.; Abshire, J. B.; Kawa, S. R.; Riris, H.; Allan, G. R.; Hasselbrack, W. E.; Numata, K.; Chen, J. R.; Sun, X.; DiGangi, J. P.; Choi, Y.

2017-12-01

Globally distributed atmospheric CO2 concentration measurements with high precision, low bias and full seasonal sampling are crucial to advance carbon cycle sciences. However, two thirds of the Earth's surface is typically covered by clouds, and passive remote sensing approaches from space are limited to cloud-free scenes. NASA Goddard is developing a pulsed, integrated-path differential absorption (IPDA) lidar approach to measure atmospheric column CO2 concentrations, XCO2, from space as a candidate for NASA's ASCENDS mission. Measurements of time-resolved laser backscatter profiles from the atmosphere also allow this technique to estimate XCO2 and range to cloud tops in addition to those to the ground with precise knowledge of the photon path-length. We demonstrate this measurement capability using airborne lidar measurements from summer 2017 ASCENDS airborne science campaign in Alaska. We show retrievals of XCO2 to ground and to a variety of cloud tops. We will also demonstrate how the partial column XCO2 to cloud tops and cloud slicing approach help resolving vertical and horizontal gradient of CO2 in cloudy conditions. The XCO2 retrievals from the lidar are validated against in situ measurements and compared to the Goddard Parameterized Chemistry Transport Model (PCTM) simulations. Adding this measurement capability to the future lidar mission for XCO2 will provide full global and seasonal data coverage and some information about vertical structure of CO2. This unique facility is expected to benefit atmospheric transport process studies, carbon data assimilation in models, and global and regional carbon flux estimation.

A-Train Data Depot: Integrating and Visualizing Atmospheric Measurements Along the A-Train Tracks

NASA Technical Reports Server (NTRS)

Kempler, Steven; Stephens, Graeme; Winker, Dave; Leptoukh, Greg; Reinke, Don; Smith, Peter

2006-01-01

The succession of US and international satellites that follow each other, seconds to minutes apart, across the local afternoon equator crossing is called the ATrain. The A-Train consists of the following satellites, in order of equator crossing: OCO, EOS Aqua, CloudSat, CALIPSO, PARASOL, and EOS Aura. Flying in such formation increases the number of observations, validates observations, and enables coordination between science observations, resulting in a more complete virtual science platform (Kelly, 2000) The goal of this project is to create the first ever A-Train virtual data portal/center, the A-Train Data Depot, to process, archive, access, visualize, analyze and correlate distributed atmosphere measurements from various A-Train instruments along A-Train tracks. The A-Train Data Depot (ATDD) will enable the free movement of remotely located A-Train data so that they are combined to create a consolidated vertical view of the Earth s Atmosphere along the A-Train tracks. Once the infrastructure of the ATDD is in place, it will be easily evolved to serve data from all A-Train data measurements: one stop shopping. The innovative approach of analyzing and visualizing atmospheric profiles along the platforms track (i.e., time) will be accommodated by reusing the GSFC Atmospheric Composition Data and Information Services Center (ACDISC) visualization and analysis tool, GIOVANNI, existing data reduction tools, on-line archwing for fast data access, and Cooperative Institute for Research in the Atmosphere (CRA) data co-registration tools. Initial measurements utilized include CALIPSO lidar backscatter, CloudSat radar reflectivity, clear air relative humidity, water vapor and temperature from AIRS, and cloud properties and aerosols from both MODIS. This will be followed by associated measurements from MLS, OMI, HIRDLS, and TES. Given the independent nature of instrument/platform development, the ATDD project has been met with many interesting challenges that, once resolved, will provide a much greater understanding of the relative flight dynamics and data co-registration of the suite of A-Train instruments, thus greatly increasing the accuracy of A-Train data analysis. Some of these challenges will be discussed. The project s resulting visualizations and analysis illustrate the importance of managing data so that measurements from various missions can be combined to enhance the understanding of the atmosphere. A-Train data management coordination, as performed here, is extremely significant in facilitating the A-Train science of clouds, precipitation, aerosol and chemistry.

Gregarious Convection and Radiative Feedbacks in Idealized Worlds

DTIC Science & Technology

2016-08-29

exist neither on the globe nor within the cloud model. Since mesoscales impose great computational costs on atmosphere models, as well as inconven...Atmospheric Science, University of Miami, Miami, Florida, USA Abstract What role does convection play in cloud feedbacks? What role does convective... cloud fields depends systematically on global temperature, then convective organization could be a climate system feedback. How reconcilable and how

Physical Validation of GPM Retrieval Algorithms Over Land: An Overview of the Mid-Latitude Continental Convective Clouds Experiment (MC3E)

NASA Technical Reports Server (NTRS)

Petersen, Walter A.; Jensen, Michael P.

2011-01-01

The joint NASA Global Precipitation Measurement (GPM) -- DOE Atmospheric Radiation Measurement (ARM) Midlatitude Continental Convective Clouds Experiment (MC3E) was conducted from April 22-June 6, 2011, centered on the DOE-ARM Southern Great Plains Central Facility site in northern Oklahoma. GPM field campaign objectives focused on the collection of airborne and ground-based measurements of warm-season continental precipitation processes to support refinement of GPM retrieval algorithm physics over land, and to improve the fidelity of coupled cloud resolving and land-surface satellite simulator models. DOE ARM objectives were synergistically focused on relating observations of cloud microphysics and the surrounding environment to feedbacks on convective system dynamics, an effort driven by the need to better represent those interactions in numerical modeling frameworks. More specific topics addressed by MC3E include ice processes and ice characteristics as coupled to precipitation at the surface and radiometer signals measured in space, the correlation properties of rainfall and drop size distributions and impacts on dual-frequency radar retrieval algorithms, the transition of cloud water to rain water (e.g., autoconversion processes) and the vertical distribution of cloud water in precipitating clouds, and vertical draft structure statistics in cumulus convection. The MC3E observational strategy relied on NASA ER-2 high-altitude airborne multi-frequency radar (HIWRAP Ka-Ku band) and radiometer (AMPR, CoSMIR; 10-183 GHz) sampling (a GPM "proxy") over an atmospheric column being simultaneously profiled in situ by the University of North Dakota Citation microphysics aircraft, an array of ground-based multi-frequency scanning polarimetric radars (DOE Ka-W, X and C-band; NASA D3R Ka-Ku and NPOL S-bands) and wind-profilers (S/UHF bands), supported by a dense network of over 20 disdrometers and rain gauges, all nested in the coverage of a six-station mesoscale rawinsonde network. As an exploratory effort to examine land-surface emissivity impacts on retrieval algorithms, and to demonstrate airborne soil moisture retrieval capabilities, the University of Tennessee Space Institute Piper aircraft carrying the MAPIR L-band radiometer was also flown during the latter half of the experiment in coordination with the ER-2. The observational strategy provided a means to sample the atmospheric column in a redundant framework that enables inter-calibration and constraint of measured and retrieved precipitation characteristics such as particle size distributions, or water contents- all within the umbrella of "proxy" satellite measurements (i.e., the ER-2). Complimenting the precipitation sampling framework, frequent and coincident launches of atmospheric soundings (e.g., 4-8/day) then provided a much larger mesoscale view of the thermodynamic and winds environment, a data set useful for initializing cloud models. The datasets collected represent a variety cloud and precipitation types including isolated cumulus clouds, severe thunderstorms, mesoscale convective systems, and widespread regions of light to moderate stratiform precipitation. We will present the MC3E experiment design, an overview of operations, and a summary of preliminary results.

Hurricane Katrina as Observed by NASA's Spaceborne Atmospheric Infrared Sounder (AIRS)

NASA Technical Reports Server (NTRS)

2005-01-01

[figure removed for brevity, see original site] Figure 1: click on image for larger AIRS microwave image

At 1:30 a.m. local time this morning, the remnants of (now Tropical Depression) Katrina were centered on the Mississippi-Tennessee border. This microwave image from the Atmospheric Infrared Sounder instrument on NASA's Aqua spacecrat shows that the area of most intense precipitation was concentrated to the north of the center of activity.

The infrared image shows how the storms look through an AIRS Infrared window channel. Window channels measure the temperature of the cloud tops or the surface of the Earth in cloud-free regions. The lowest temperatures are associated with high, cold cloud tops that make up the top of the hurricane. The infrared signal does not penetrate through clouds, so the purple color indicates the cool cloud tops of the storm. In cloud-free areas, the infrared signal is retrieved at the Earth's surface, revealing warmer temperatures. Cooler areas are pushing to purple and warmer areas are pushing to red.

The microwave image (figure 1) reveals where the heaviest precipitation in the hurricane is taking place. The blue areas within the storm show the location of this heavy precipitation. Blue areas outside of the storm where there are moderate or no clouds are where the cold (in the microwave sense) sea surface shines through.

The Atmospheric Infrared Sounder Experiment, with its visible, infrared, and microwave detectors, provides a three-dimensional look at Earth's weather. Working in tandem, the three instruments can make simultaneous observations all the way down to the Earth's surface, even in the presence of heavy clouds. With more than 2,000 channels sensing different regions of the atmosphere, the system creates a global, 3-D map of atmospheric temperature and humidity and provides information on clouds, greenhouse gases, and many other atmospheric phenomena. The AIRS Infrared Sounder Experiment flies onboard NASA's Aqua spacecraft and is managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif., under contract to NASA. JPL is a division of the California Institute of Technology in Pasadena.

Dynamic mineral clouds on HD 189733b. II. Monte Carlo radiative transfer for 3D cloudy exoplanet atmospheres: combining scattering and emission spectra

NASA Astrophysics Data System (ADS)

Lee, G. K. H.; Wood, K.; Dobbs-Dixon, I.; Rice, A.; Helling, Ch.

2017-05-01

Context. As the 3D spatial properties of exoplanet atmospheres are being observed in increasing detail by current and new generations of telescopes, the modelling of the 3D scattering effects of cloud forming atmospheres with inhomogeneous opacity structures becomes increasingly important to interpret observational data. Aims: We model the scattering and emission properties of a simulated cloud forming, inhomogeneous opacity, hot Jupiter atmosphere of HD 189733b. We compare our results to available Hubble Space Telescope (HST) and Spitzer data and quantify the effects of 3D multiple scattering on observable properties of the atmosphere. We discuss potential observational properties of HD 189733b for the upcoming Transiting Exoplanet Survey Satellite (TESS) and CHaracterising ExOPlanet Satellite (CHEOPS) missions. Methods: We developed a Monte Carlo radiative transfer code and applied it to post-process output of our 3D radiative-hydrodynamic, cloud formation simulation of HD 189733b. We employed three variance reduction techniques, I.e. next event estimation, survival biasing, and composite emission biasing, to improve signal to noise of the output. For cloud particle scattering events, we constructed a log-normal area distribution from the 3D cloud formation radiative-hydrodynamic results, which is stochastically sampled in order to model the Rayleigh and Mie scattering behaviour of a mixture of grain sizes. Results: Stellar photon packets incident on the eastern dayside hemisphere show predominantly Rayleigh, single-scattering behaviour, while multiple scattering occurs on the western hemisphere. Combined scattered and thermal emitted light predictions are consistent with published HST and Spitzer secondary transit observations. Our model predictions are also consistent with geometric albedo constraints from optical wavelength ground-based polarimetry and HST B band measurements. We predict an apparent geometric albedo for HD 189733b of 0.205 and 0.229, in the TESS and CHEOPS photometric bands respectively. Conclusions: Modelling the 3D geometric scattering effects of clouds on observables of exoplanet atmospheres provides an important contribution to the attempt to determine the cloud properties of these objects. Comparisons between TESS and CHEOPS photometry may provide qualitative information on the cloud properties of nearby hot Jupiter exoplanets.

Tropical Depression Debbie in the Atlantic

NASA Technical Reports Server (NTRS)

2006-01-01

[figure removed for brevity, see original site] [figure removed for brevity, see original site] Microwave ImageVisible Light Image

Infrared Image These images show Tropical Depression Debbie in the Atlantic, from the Atmospheric Infrared Sounder (AIRS) on NASA's Aqua satellite on August 22, 2006. This AIRS image shows the temperature of the cloud tops or the surface of the Earth in cloud-free regions. The lowest temperatures (in purple) are associated with high, cold cloud tops that make up the top of the storm. The infrared signal does not penetrate through clouds. Where there are no clouds the AIRS instrument reads the infrared signal from the surface of the Earth, revealing warmer temperatures (red). At the time the data were taken from which these images were made the eye had not yet opened but the storm is now well organized. The location of the future eye appears as a circle at 275 K brightness temperature in the microwave image just to the SE of the Azores.

Microwave Image The microwave image is created from microwave radiation emitted by Earth's atmosphere and received by the instrument. It shows where the heaviest rainfall is taking place (in blue) in the storm. Blue areas outside of the storm where there are either some clouds or no clouds, indicate where the sea surface shines through.

Vis/NIR Image Tropical Depression Debbie captured by the visible light/near-infrared sensor on the AIRS instrument.

The Atmospheric Infrared Sounder Experiment, with its visible, infrared, and microwave detectors, provides a three-dimensional look at Earth's weather. Working in tandem, the three instruments can make simultaneous observations all the way down to the Earth's surface, even in the presence of heavy clouds. With more than 2,000 channels sensing different regions of the atmosphere, the system creates a global, 3-D map of atmospheric temperature and humidity and provides information on clouds, greenhouse gases, and many other atmospheric phenomena. The AIRS Infrared Sounder Experiment flies onboard NASA's Aqua spacecraft and is managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif., under contract to NASA. JPL is a division of the California Institute of Technology in Pasadena.

Instrumentation for surveying the lower part of the atmosphere in extremes conditions

NASA Astrophysics Data System (ADS)

Gobinddass, Marie-Line; Molinie, Jack; Richard, Sandrine; Jean-Louis, Sabrina

To observe atmospheric phenomena such as clouds, precipitation and wind in order to understand how they form and evolve meteorologists use few instruments which allows to measure parameters as temperature, pressure and humidity. In the specific case of Kourou region where the French Space Agency is located the environment and safeguard group works on protecting biodiversity in and around the center. By considering a few scientific challenges in atmospheric science one of the main topics of this work consists on the understanding of the fluctuation of the atmosphere due to natural or industrials perturbations. We have considered a few experiences with many instruments in a large space of more than 1200 km per square. To differentiate and try to quantify industrial cloud from natural cloud or from natural atmosphere, the idea of using a drone has been experimented. The ratio of the cost of such experimentation with the relevance of the results which can be obtained will be discussed here. It is necessary to take into account the turbulence in the atmosphere due to industrial acid cloud or hot cloud. Finally, instead of taking the risk of having airbone measurements with a pilot we have thought of the tetherball due to it lower cost and for security reason. The technical experiment and few type of results will be presented here.

From aerosol-limited to invigoration of warm convective clouds.

PubMed

Koren, Ilan; Dagan, Guy; Altaratz, Orit

2014-06-06

Among all cloud-aerosol interactions, the invigoration effect is the most elusive. Most of the studies that do suggest this effect link it to deep convective clouds with a warm base and cold top. Here, we provide evidence from observations and numerical modeling of a dramatic aerosol effect on warm clouds. We propose that convective-cloud invigoration by aerosols can be viewed as an extension of the concept of aerosol-limited clouds, where cloud development is limited by the availability of cloud-condensation nuclei. A transition from pristine to slightly polluted atmosphere yields estimated negative forcing of ~15 watts per square meter (cooling), suggesting that a substantial part of this anthropogenic forcing over the oceans occurred at the beginning of the industrial era, when the marine atmosphere experienced such transformation. Copyright © 2014, American Association for the Advancement of Science.

Impacts of the cloud structure's latitudinal variation on the general circulation of the Venus atmosphere as modeled by the LMD-GCM

NASA Astrophysics Data System (ADS)

Garate-Lopez, Itziar; Lebonnois, Sébastien

2017-04-01

A new simulation of Venus atmospheric circulation obtained with the LMD Venus GCM is described and the impact of cloud's latitudinal structure on the general circulation is analyzed. The model used here is based on that presented in Lebonnois et al. (2016). However, in the present simulation we consider the latitudinal variation of the cloud structure (Haus et al., 2014) both for the solar heating and to compute the infrared net-exchange rate matrix used in the radiative transfer module. The new cloud treatment affects mainly the balance in the angular momentum and the zonal wind distribution. Consequently, the agreement between the vertical profile of the modeled mean zonal wind and the profiles measured by different probes, is clearly improved from previous simulations in which zonal winds below the clouds were weak (roughly half the observed values). Moreover, the equatorial jet obtained at the base of the cloud deck is now more consistent with the observations. In Lebonnois et al. (2016) it was too strong compared to mid-latitudes, but in the present simulation the equatorial jet is less intense than the mid-latitude jets, in concordance with cloud-tracking measurements (Hueso et al., 2015). Since the atmospheric waves play a crucial role in the angular momentum budget of the Venus's atmospheric circulation, we analyze the wave activity by means of the Fast Fourier Transform technique studying the frequency spectrum of temperature, zonal and meridional wind fields. Modifications in the activity of the different types of waves present in the Venusian atmosphere compared to Lebonnois et al. (2016) are discussed, in terms of horizontal and vertical transport of the angular momentum by diurnal and semi-diurnal tides, barotropic and baroclinic waves, and Rossby and Kelvin type waves. Haus R., Kappel D. and Arnold G., 2014. Atmospheric thermal structure and cloud features in the southern hemisphere of Venus as retrieved from VIRTIS/VEX radiation measurements. Icarus 232, 232-248. Hueso R., Peralta J., Garate-Lopez I., et al., 2015. Six years of Venus winds at the upper cloud level from UV, visible and near infrared observations from VIRTIS on Venus express. Planet. Space Sci. 113-114, 78-99. Lebonnois S., Sugimoto N., and Gilli G., 2016. Wave analysis in the atmosphere of Venus below 100km altitude, simulated by the LMD Venus GCM. Icarus 278, 38-51.

Retrieval of volcanic ash properties from the Infrared Atmospheric Sounding Interferometer (IASI)

NASA Astrophysics Data System (ADS)

Ventress, Lucy; Carboni, Elisa; Smith, Andrew; Grainger, Don; Dudhia, Anu; Hayer, Catherine

2014-05-01

The Infrared Atmospheric Sounding Interferometer (IASI), on board both the MetOp-A and MetOp-B platforms, is a Fourier transform spectrometer covering the mid-infrared (IR) from 645-2760cm-1 (3.62-15.5 μm) with a spectral resolution of 0.5cm-1 (apodised) and a pixel diameter at nadir of 12km. These characteristics allow global coverage to be achieved twice daily for each instrument and make IASI a very useful tool for the observation of larger aerosol particles (such as desert dust and volcanic ash) and the tracking of volcanic plumes. In recent years, following the eruption of Eyjafjallajökull, interest in the the ability to detect and characterise volcanic ash plumes has peaked due to the hazards to aviation. The thermal infrared spectra shows a rapid variation with wavelength due to absorption lines from atmospheric and volcanic gases as well as broad scale features principally due to particulate absorption. The ash signature depends upon both the composition and size distribution of ash particles as well as the altitude of the volcanic plume. To retrieve ash properties, IASI brightness temperature spectra are analysed using an optimal estimation retrieval scheme and a forward model based on RTTOV. Initially, IASI pixels are flagged for the presence of volcanic ash using a linear retrieval detection method based on departures from a background state. Given a positive ash signal, the RTTOV output for a clean atmosphere (containing atmospheric gases but no cloud or aerosol/ash) is combined with an ash/cloud layer using the same scheme as for the Oxford-RAL Retrieval of Aerosol and Cloud (ORAC) algorithm. The retrieved parameters are ash optical depth (at a reference wavelength of 550nm), ash effective radius, layer altitude and surface temperature. The potential for distinguishing between different ash types is explored and a sensitivity study of the retrieval algorithm is presented. Results are shown from studies of the evolution and composition of ash plumes for recent volcanic eruptions.

Sensitivity of Boreal-Summer Circulation and Precipitation to Atmospheric Aerosols in Selected Regions. Part 2; The Americas

NASA Technical Reports Server (NTRS)

Wilcox, E. M.; Sud, Y. C.; Walker, G.

2009-01-01

Aerosol perturbations over selected land regions are imposed in Version-4 of the Goddard Earth Observing System (GEOS-4) general circulation model (GCM) to assess the influence of increasing aerosol concentrations on regional circulation patterns and precipitation in four selected regions: India, Africa, and North and South America. Part 1 of this paper addresses the responses to aerosol perturbations in India and Africa. This paper presents the same for aerosol perturbations over the Americas. GEOS-4 is forced with prescribed aerosols based on climatological data, which interact with clouds using a prognostic scheme for cloud microphysics including aerosol nucleation of water and ice cloud hydrometeors. In clear-sky conditions the aerosols interact with radiation. Thus the model includes comprehensive physics describing the aerosol direct and indirect effects on climate (hereafter ADE and AIE respectively). Each simulation is started from analyzed initial conditions for 1 May and was integrated through June-July-August of each of the six years: 1982 1987 to provide a 6-ensemble set. Results are presented for the difference between simulations with double the climatological aerosol concentration and one-half the climatological aerosol concentration for three experiments: two where the ADE and AIE are applied separately and one in which both the ADE and AIE are applied. The ADE and AIE both yield reductions in net radiation at the top of the atmosphere and surface while the direct absorption of shortwave radiation contributes a net radiative heating in the atmosphere. A large net heating of the atmosphere is also apparent over the subtropical North Atlantic Ocean that is attributable to the large aerosol perturbation imposed over Africa. This atmospheric warming and the depression of the surface pressure over North America contribute to a northward shift of the inter-Tropical Convergence Zone over northern America, an increase in precipitation over Central America and the Caribbean, and an enhancement of convergence in the North American monsoon region.

Unmanned Aerial Systems, Moored Balloons, and the U.S. Department of Energy ARM Facilities in Alaska

NASA Astrophysics Data System (ADS)

Ivey, Mark; Verlinde, Johannes

2014-05-01

The U.S. Department of Energy (DOE), through its scientific user facility, the Atmospheric Radiation Measurement (ARM) Climate Research Facility, provides scientific infrastructure and data to the international Arctic research community via its research sites located on the North Slope of Alaska. Facilities and infrastructure to support operations of unmanned aerial systems for science missions in the Arctic and North Slope of Alaska were established at Oliktok Point Alaska in 2013. Tethered instrumented balloons will be used in the near future to make measurements of clouds in the boundary layer including mixed-phase clouds. The DOE ARM Program has operated an atmospheric measurement facility in Barrow, Alaska, since 1998. Major upgrades to this facility, including scanning radars, were added in 2010. Arctic Observing Networks are essential to meet growing policy, social, commercial, and scientific needs. Calibrated, high-quality arctic geophysical datasets that span ten years or longer are especially important for climate studies, climate model initializations and validations, and for related climate policy activities. For example, atmospheric data and derived atmospheric forcing estimates are critical for sea-ice simulations. International requirements for well-coordinated, long-term, and sustained Arctic Observing Networks and easily-accessible data sets collected by those networks have been recognized by many high-level workshops and reports (Arctic Council Meetings and workshops, National Research Council reports, NSF workshops and others). The recent Sustaining Arctic Observation Network (SAON) initiative sponsored a series of workshops to "develop a set of recommendations on how to achieve long-term Arctic-wide observing activities that provide free, open, and timely access to high-quality data that will realize pan-Arctic and global value-added services and provide societal benefits." This poster will present information on opportunities for members of the arctic research community to make atmospheric measurements using unmanned aerial systems or tethered balloons.

Sensitivity of the southern West African mean atmospheric state to variations in low-level cloud cover as simulated by ICON

NASA Astrophysics Data System (ADS)

Kniffka, Anke; Knippertz, Peter; Fink, Andreas

2017-04-01

This contribution presents first results of numerical sensitivity experiments that are carried out in the framework of the project DACCIWA (Dynamics-Aerosol-Chemistry-Cloud Interactions in West Africa). DACCIWA aims to investigate the impact of the drastic increase in anthropogenic emissions in West Africa on the local weather and climate, for example through cloud-aerosol interactions or impacts on radiation and stability. DACCIWA organised a major international field campaign in West Africa in June-July 2016 and involves a wide range of modelling activities. Several studies have shown - and first results of the DACCIWA campaign confirm - that extensive ultra-low stratus clouds form in the southern parts of West Africa (8°W-8°E, 5-10°N) at night in connection with strong nocturnal low-level jets. The clouds persist long after sunrise and have therefore a substantial impact on the surface radiation budget and consequently on the diurnal evolution of the daytime, convectively mixed boundary layer. The objective of this study is to investigate the sensitivity of the West African monsoon system and its diurnal cycle to the radiative effects of these low clouds. The study is based on a series of daily 5-day sensitivity simulations using ICON, the operational numerical weather prediction model of the German Weather Service during the months July - September 2006. In these simulations, low clouds are made transparent, by artificially lowering the optical thickness information passed on to the model's radiation scheme. Results reveal a noticeable influence of the low-level cloud cover on the atmospheric mean state of our region of interest and beyond. Also the diurnal development of the convective boundary layer is influenced by the cloud modification. In the transparent-cloud experiments, the cloud deck tends to break up later in the day and is shifted to a higher altitude, thereby causing a short-lived intensification around 11 LT. The average rainfall patterns are modified as well, though no conclusion on the long-term impact on rainfall can be made due to the forced initial conditions in the presented experiment. In the future, the impact on the development of the West African monsoon system will be assessed.

Airborne lidar/radiometric measurements of cirrus cloud parameters and their application to LOWTRAN radiance evaluations

NASA Technical Reports Server (NTRS)

Uthe, Edward E.

1990-01-01

SRI has assembled an airborne lidar/radiometric instrumentation suite for mapping cirrus cloud distribution and analyzing cirrus cloud optical properties. Operation of upward viewing infrared radiometers from an airborne platform provides the optimum method of measuring high altitude cold cloud radiative properties with minimum interference from the thermal emission by the earth's surface and lower atmospheric components. Airborne installed sensors can also operate over large regional areas including water, urban, and mountain surfaces and above lower atmospheric convective clouds and haze layers. Currently available sensors installed on the SRI Queen Air aircraft are illustrated. Lidar and radiometric data records are processed for real time viewing on a color video screen. A cirrus cloud data example is presented as a black and white reproduction of a color display of data at the aircraft altitude of 12,000 ft, the 8 to 14 micron atmospheric radiation background was equivalent to a blackbody temperature of about -60 C and, therefore, the radiometer did not respond strongly to low density cirrus cloud concentrations detected by the lidar. Cloud blackbody temperatures (observed by radiometer) are shown plotted against midcloud temperatures (derived from lidar observed cloud heights and supporting temperature profiles) for data collected on 30 June and 28 July.

Remote sensing of three-dimensional cirrus clouds from satellites: application to continuous-wave laser atmospheric transmission and backscattering.

PubMed

Liou, K N; Ou, Szu-Cheng; Takano, Yoshihide; Cetola, Jeffrey

2006-09-10

A satellite remote sensing methodology has been developed to retrieve 3D ice water content (IWC) and mean effective ice crystal size of cirrus clouds from satellite data on the basis of a combination of the conventional retrieval of cloud optical depth and particle size in a horizontal plane and a parameterization of the vertical cloud profile involving temperature from sounding and/or analysis. The inferred 3D cloud fields of IWC and mean effective ice crystal size associated with two impressive cirrus clouds that occurred in the vicinity of northern Oklahoma on 18 April 1997 and 9 March 2000, obtained from the Department of Energy's Atmospheric Radiation Measurement Program, have been validated against the ice crystal size distributions that were collected independently from collocated and coincident aircraft optical probe measurements. The 3D cloud results determined from satellite data have been applied to the simulation of cw laser energy propagation, and we show the significance of 3D cloud geometry and inhomogeneity and spherical atmosphere on the transmitted and backscattered laser powers. Finally, we demonstrate that the 3D cloud fields derived from satellite remote sensing can be used for the 3D laser transmission and backscattering model for tactical application.

Snow precipitation on Mars driven by cloud-induced night-time convection

NASA Astrophysics Data System (ADS)

Spiga, Aymeric; Hinson, David P.; Madeleine, Jean-Baptiste; Navarro, Thomas; Millour, Ehouarn; Forget, François; Montmessin, Franck

2017-09-01

Although it contains less water vapour than Earth's atmosphere, the Martian atmosphere hosts clouds. These clouds, composed of water-ice particles, influence the global transport of water vapour and the seasonal variations of ice deposits. However, the influence of water-ice clouds on local weather is unclear: it is thought that Martian clouds are devoid of moist convective motions, and snow precipitation occurs only by the slow sedimentation of individual particles. Here we present numerical simulations of the meteorology in Martian cloudy regions that demonstrate that localized convective snowstorms can occur on Mars. We show that such snowstorms--or ice microbursts--can explain deep night-time mixing layers detected from orbit and precipitation signatures detected below water-ice clouds by the Phoenix lander. In our simulations, convective snowstorms occur only during the Martian night, and result from atmospheric instability due to radiative cooling of water-ice cloud particles. This triggers strong convective plumes within and below clouds, with fast snow precipitation resulting from the vigorous descending currents. Night-time convection in Martian water-ice clouds and the associated snow precipitation lead to transport of water both above and below the mixing layers, and thus would affect Mars' water cycle past and present, especially under the high-obliquity conditions associated with a more intense water cycle.

Remote sensing of three-dimensional cirrus clouds from satellites: application to continuous-wave laser atmospheric transmission and backscattering

NASA Astrophysics Data System (ADS)

Liou, K. N.; Ou, Szu-Cheng; Takano, Yoshihide; Cetola, Jeffrey

2006-09-01

A satellite remote sensing methodology has been developed to retrieve 3D ice water content (IWC) and mean effective ice crystal size of cirrus clouds from satellite data on the basis of a combination of the conventional retrieval of cloud optical depth and particle size in a horizontal plane and a parameterization of the vertical cloud profile involving temperature from sounding and/or analysis. The inferred 3D cloud fields of IWC and mean effective ice crystal size associated with two impressive cirrus clouds that occurred in the vicinity of northern Oklahoma on 18 April 1997 and 9 March 2000, obtained from the Department of Energy's Atmospheric Radiation Measurement Program, have been validated against the ice crystal size distributions that were collected independently from collocated and coincident aircraft optical probe measurements. The 3D cloud results determined from satellite data have been applied to the simulation of cw laser energy propagation, and we show the significance of 3D cloud geometry and inhomogeneity and spherical atmosphere on the transmitted and backscattered laser powers. Finally, we demonstrate that the 3D cloud fields derived from satellite remote sensing can be used for the 3D laser transmission and backscattering model for tactical application.

Study on Microwave Remote Sensing of Atmosphere, Cloud and Rain

NASA Astrophysics Data System (ADS)

Bolin, Zhao

1990-12-01

In this paper, recent research of microwave remote sensing of atmosphere, cloud and rain in China is presented. It includes the following aspects: >(1) Progress in the development of multifrequency radiometer and its characteristics and parameters;

Responses of Cloud Type Distributions to the Large-Scale Dynamical Circulation: Water Budget-Related Dynamical Phase Space and Dynamical Regimes

NASA Technical Reports Server (NTRS)

Wong, Sun; Del Genio, Anthony; Wang, Tao; Kahn, Brian; Fetzer, Eric J.; L'Ecuyer, Tristan S.

2015-01-01

Goals: Water budget-related dynamical phase space; Connect large-scale dynamical conditions to atmospheric water budget (including precipitation); Connect atmospheric water budget to cloud type distributions.

The July 2016 Study of the water VApour in the polar AtmosPhere (SVAAP) campaign at Thule, Greenland: surface radiation budget and role of clouds

NASA Astrophysics Data System (ADS)

Meloni, Daniela; Di Iorio, Tatiana; di Sarra, Alcide; Iaccarino, Antonio; Pace, Giandomenico; Mevi, Gabriele; Muscari, Giovanni; Cacciani, Marco; Gröbner, Julian

2017-04-01

The Study of the water VApour in the polar AtmosPhere (SVAAP) project, funded by the Italian Programme for Antarctic Research, is aimed at investigating the surface radiation budget (SRB), the variability of atmospheric water vapour, and the long-term variations in stratospheric composition and structure at Thule, Greenland, in the framework of the international Network for Detection of Atmospheric Composition Change (NDACC). Thule High Arctic Atmospheric Observatory (THAAO, 76.5° N, 68.8° W) is devoted to study climate change and has been operational since 1990, with the contribution of different international institutions: DMI, NCAR, ENEA, INGV, Universities of Roma and Firenze (http://www.thuleatmos-it.it). As part of SVAAP an intensive field campaign was held at Thule from 5 to 28 July 2016. The campaign was also aimed at supporting the installation of VESPA-22, a new microwave radiometer for water vapour profiling in the upper atmosphere and integrated water vapour (IWV), and offered the possibility to study the cloud physical and optical properties and their impact on the SRB. Measurements of downward shortwave (SW) and longwave (LW) irradiance were already available since 2009. Additional observations were added to obtain the SRB and to characterize the atmospheric state: upward SW and LW irradiance, upwelling and downwelling photosynthetically active radiation (PAR), downward irradiance in the 8-14 µm infrared window, temperature and relative humidity tropospheric profiles, IWV, liquid water path (LWP), lidar tropospheric backscattering profiles, sky brightness temperature (BT) in the 9.6-11.5 µm spectral range, visible and infrared sky images, surface meteorological parameters. Moreover, 23 radiosonde were launched during the campaign. Data from the period 14-28 July are presented in this study. The first part of the campaign was characterized by stable cloud-free conditions, while alternation of cloudy and cloud-free sky occurred after 18 July. The time evolution of SW and LW SRB, surface albedo, and derived cloud parameters, such as cloud optical thickness and effective radius, are presented and discussed. Thickest clouds reached visible optical depths of about 200, and values of LWP of about 0.4 kg/m2. While the SW SRB is always positive during the measurement campaign, the LW SRB is negative under cloud-free conditions (own to -100 W/m2 at noon), becoming positive (up to +50 W/m2) during cloudy periods. The total (SW+LW) SRB is positive and its variability is dominated by the SW irradiance. Clouds induce a reduction of the SRB compared to the cloud-free periods, thanks to the dominant SW effect. The LW component offsets about 20% of the SW at noon in clear sky, and contributes up to 50% of the total SRB in thick cloud conditions. The availability of the cloud physical and optical properties and the atmospheric vertical profiles allow to study in details the SW and LW cloud radiative effect by means of radiative transfer simulations performed with MODTRAN6.0 model.

Parametric studies with an atmospheric diffusion model that assesses toxic fuel hazards due to the ground clouds generated by rocket launches

NASA Technical Reports Server (NTRS)

Stewart, R. B.; Grose, W. L.

1975-01-01

Parametric studies were made with a multilayer atmospheric diffusion model to place quantitative limits on the uncertainty of predicting ground-level toxic rocket-fuel concentrations. Exhaust distributions in the ground cloud, cloud stabilized geometry, atmospheric coefficients, the effects of exhaust plume afterburning of carbon monoxide CO, assumed surface mixing-layer division in the model, and model sensitivity to different meteorological regimes were studied. Large-scale differences in ground-level predictions are quantitatively described. Cloud alongwind growth for several meteorological conditions is shown to be in error because of incorrect application of previous diffusion theory. In addition, rocket-plume calculations indicate that almost all of the rocket-motor carbon monoxide is afterburned to carbon dioxide CO2, thus reducing toxic hazards due to CO. The afterburning is also shown to have a significant effect on cloud stabilization height and on ground-level concentrations of exhaust products.

The thermal balance of the lower atmosphere of Venus

NASA Technical Reports Server (NTRS)

Tomasko, M. G.

1981-01-01

The temperature near the surface of Venus (now established at 730 K) is remarkably high in view of Venus's cloud cover which causes the planet to absorb even less sunlight than does Earth. Early attempts to understand the thermal balance that leads to this unusual state were hindered by the lack of basic information regarding the composition, temperature-pressure structure, cloud properties, and wind field of the lower atmosphere. A series of successful space missions have measured many of the above quantities that control the transfer of heat in Venus's lower atmosphere. The relevant observational data are summarized and the attempts to understand the thermal balance of Venus's atmosphere below the cloud tops are reviewed. The data indicate that sufficient sunlight penetrates to deep atmospheric levels and is trapped by the large thermal opacity of the atmosphere to essentially account for the high temperatures observed.

Senstitivity analysis of horizontal heat and vapor transfer coefficients for a cloud-topped marine boundary layer during cold-air outbreaks. M.S. Thesis

NASA Technical Reports Server (NTRS)

Chang, Y. V.

1986-01-01

The effects of external parameters on the surface heat and vapor fluxes into the marine atmospheric boundary layer (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 layer 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 cloud topped boundary layer on the external parameters (wind speed, divergence, sea surface temperature, radiative sky temperature, cloud 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.

The CLouds-Aerosol-Radiation Interaction and Forcing: Year 2017 (CLARIFY-2017) programme: deployment, synergies with ORACLES/LASIC/AEROCLO-SA and initial results

NASA Astrophysics Data System (ADS)

Haywood, J. M.; Abel, S.; Langridge, J.; Coe, H.; Blyth, A. M.; Bellouin, N.; Stier, P.; Field, P.; Carslaw, K. S.; Brooks, M.

2017-12-01

The CLoud-Aerosol-Radiation Interaction and Forcing: Year 2017 (CLARIFY-2017) programme is the UK's contribution to the intensive investigation of clouds, aerosols, and impacts on the radiation budget and hence climate over the South East Atlantic which centred on the deployment of the UK's FAAM BAe146 atmospheric research aircraft to Ascension Island in August/September 2017. There are strong synergies with the NASA ORACLES deployments of US NASA P3 and ER2 aircraft to Walvis Bay in August/September 2016 and Sao Tome in August 2017, the LASIC project which deployed the ARM Mobile Facility to Ascension Island in 2016/2017, and the AEROCLO-SA project which deployed the French research aircraft to Walvis Bay in September 2017. This talk will describe the forecasting tools that were developed and used in order to place the aircraft in the right place at the right time and will give an overview of the deployment. Initial results from a range of model, remote sensing and in-situ sampling instruments will be presented and compared against the findings of the other synergistic campaigns.

Assessing Spectral Shortwave Cloud Observations at the Southern Great Plains Facility

NASA Technical Reports Server (NTRS)

McBride, P. J.; Marshak, A.; Wiscombe, W. J.; Flynn, C. J.; Vogelmann, A. M.

2012-01-01

The Atmospheric Radiation Measurement (ARM) program (now Atmospheric System Research) was established, in part, to improve radiation models so that they could be used reliably to compute radiation fluxes through the atmosphere, given knowledge of the surface albedo, atmospheric gases, and the aerosol and cloud properties. Despite years of observations, discrepancies still exist between radiative transfer models and observations, particularly in the presence of clouds. Progress has been made at closing discrepancies in the spectral region beyond 3 micron, but the progress lags at shorter wavelengths. Ratios of observed visible and near infrared cloud albedo from aircraft and satellite have shown both localized and global discrepancies between model and observations that are, thus far, unexplained. The capabilities of shortwave surface spectrometry have been improved in recent years at the Southern Great Plains facility (SGP) of the ARM Climate Research Facility through the addition of new instrumentation, the Shortwave Array Spectroradiometer, and upgrades to existing instrumentation, the Shortwave Spectroradiometer and the Rotating Shadowband Spectroradiometer. An airborne-based instrument, the HydroRad Spectroradiometer, was also deployed at the ARM site during the Routine ARM Aerial Facility Clouds with Low Optical Water Depths (CLOWD) Optical Radiative Observations (RACORO) field campaign. Using the new and upgraded spectral observations along with radiative transfer models, cloud scenes at the SGP are presented with the goal of characterizing the instrumentation and the cloud fields themselves.

Cloud Thickness from Offbeam Returns (THOR) Validation Campaign on NASA's P3B Over the ARM/SGP

NASA Technical Reports Server (NTRS)

Cahalan, R. F.; Kolasinski, J.; McGill, M.; Lau, William K. M. (Technical Monitor)

2002-01-01

Physical thickness of a cloud layer, sometimes multiple cloud layers, is a crucial controller of solar heating of the Earth- atmosphere system, which drives the convective processes that produce storm systems. Yet clouds of average optical thickness are opaque to conventional lidar, so their thickness is well estimated only by combining a lidar above and another below cloud, or a radar and lidar on the same side, dual facilities not widely available. Here we report initial observations of a new airborne multiple field of view lidar, capable of determining physical thickness of cloud layers from time signatures of off-beam returns from a I kHz micropulse lidar at 540 rim. For a single layer, the time delay of light returning from the outer diffuse halo of light surrounding the beam entry point, relative to the time delay at beam center, determines the cloud physical thickness. The delay combined with the pulse stretch gives the optical thickness. This halo method requires cloud optical thickness exceeding 2, and improves with cloud thickness, thus complimenting conventional lidar, which cannot penetrate thick clouds. Results are presented from March 25, 2002, when THOR flew a butterfly pattern over the ARM site at 8.3 km, above a thin ice cloud at 5 km, and a thick boundary-layer stratus deck with top at 1.3 km, as shown by THOR channel 1, and a base at about 0.3 km as shown by the ground-based MPL. Additional information is included in the original extended abstract.

Scientific goals of the Cooperative Multiscale Experiment (CME)

NASA Technical Reports Server (NTRS)

Cotton, William

1993-01-01

Mesoscale Convective Systems (MCS) form the focus of CME. Recent developments in global climate models, the urgent need to improve the representation of the physics of convection, radiation, the boundary layer, and orography, and the surge of interest in coupling hydrologic, chemistry, and atmospheric models of various scales, have emphasized the need for a broad interdisciplinary and multi-scale approach to understanding and predicting MCS's and their interactions with processes at other scales. The role of mesoscale systems in the large-scale atmospheric circulation, the representation of organized convection and other mesoscale flux sources in terms of bulk properties, and the mutually consistent treatment of water vapor, clouds, radiation, and precipitation, are all key scientific issues concerning which CME will seek to increase understanding. The manner in which convective, mesoscale, and larger scale processes interact to produce and organize MCS's, the moisture cycling properties of MCS's, and the use of coupled cloud/mesoscale models to better understand these processes, are also major objectives of CME. Particular emphasis will be placed on the multi-scale role of MCS's in the hydrological cycle and in the production and transport of chemical trace constituents. The scientific goals of the CME consist of the following: understand how the large and small scales of motion influence the location, structure, intensity, and life cycles of MCS's; understand processes and conditions that determine the relative roles of balanced (slow manifold) and unbalanced (fast manifold) circulations in the dynamics of MCS's throughout their life cycles; assess the predictability of MCS's and improve the quantitative forecasting of precipitation and severe weather events; quantify the upscale feedback of MCS's to the large-scale environment and determine interrelationships between MCS occurrence and variations in the large-scale flow and surface forcing; provide a data base for initialization and verification of coupled regional, mesoscale/hydrologic, mesoscale/chemistry, and prototype mesoscale/cloud-resolving models for prediction of severe weather, ceilings, and visibility; provide a data base for initialization and validation of cloud-resolving models, and for assisting in the fabrication, calibration, and testing of cloud and MCS parameterization schemes; and provide a data base for validation of four dimensional data assimilation schemes and algorithms for retrieving cloud and state parameters from remote sensing instrumentation.

Radiative Susceptibility of Cloudy Atmospheres to Droplet Number Perturbations: 1. Theoretical Analysis and Examples from MODIS

NASA Technical Reports Server (NTRS)

Platnick, Steven; Oreopoulos, Lazaros

2008-01-01

Theoretical and satellite-based assessments of the sensitivity of broadband shortwave radiative fluxes in cloudy atmospheres to small perturbations in the cloud droplet number concentration (N) of liquid water clouds under constant water conditions are performed. Two approaches to study this sensitivity are adopted: absolute increases in N, for which the radiative response is referred to as absolute cloud susceptibility, and relative increases in N or relative cloud susceptibility. Estimating the former is more challenging as it requires an assumed value for either cloud liquid water content or geometrical thickness; both susceptibilities require an assumed relationship between the droplet volume and effective radius. Expanding upon previous susceptibility studies, present radiative calculations include the effect of AN perturbations on droplet asymmetry parameter and single-scattering albedo, in addition to extinction. Absolute cloud susceptibility has a strong nonlinear dependence on the droplet effective radius as expected, while relative cloud susceptibility is primarily dependent on optical thickness. Molecular absorption and reflecting surfaces both reduce the relative contribution of the cloud to the top-of-atmosphere (TOA) flux and therefore also reduce the TOA albedo susceptibility. Transmittance susceptibilities are negative with absolute values similar to albedo susceptibility, while atmospheric absorptance susceptibilities are about an order of magnitude smaller than albedo susceptibilities and can be either positive or negative. Observation-based susceptibility calculations are derived from MODIS pixel-level retrievals of liquid water cloud optical thickness, effective radius, and cloud top temperature; two data granule examples are shown. Susceptibility quantifies the aerosol indirect effect sensitivity in a way that can be easily computed from model fields. As such, susceptibilities derived from MODIS observations provide a higher-order test of model cloud properties used for indirect effect studies. MODIS-derived global distributions of cloud susceptibility and radiative forcing calculations are presented in a companion paper.

Dynamics of Clouds and Mesoscale Circulations over the Maritime Continent

NASA Astrophysics Data System (ADS)

Jin, Y.; Wang, S.; Xian, P.; Reid, J. S.; Nachamkin, J.

2010-12-01

In recent decades Southeast Asia (SEA) has seen rapid economic growth as well as increased biomass burning, resulting in high air pollution levels and reduced air qual-ity. At the same time clouds often prevent accurate air-quality monitoring and analysis using satellite observations. The Seven SouthEast Asian Studies (7SEAS) field campaign currently underway over SEA provides an unprecedented opportunity to study the com-plex interplay between aerosol and clouds. 7SEAS is a comprehensive interdisciplinary atmospheric sciences program through international partnership of NASA, NRL, ONR and seven local institutions including those from Indonesia, Malaysia, the Philippines, Singapore, Taiwan, Thailand, and Vietnam. While the original goal of 7SEAS is to iso-late the impacts of aerosol particles on weather and the environment, it is recognized that better understanding of SEA meteorological conditions, especially those associated with cloud formation and evolution, is critical to the success of the campaign. In this study we attempt to gain more insight into the dynamic and physical processes associated with low level clouds and atmospheric circulation at the regional scale over SEA, using the Navy’s Coupled Ocean/Atmosphere Mesoscale Prediction System (COAMPS® ), a regional forecast model in operation at FNMOC since 1998. This effort comprises two main components. First, multiple-years of COAMPS operational forecasts over SEA are analyzed for basic climatology of atmospheric fea-tures. Second, mesoscale circulation and cloud properties are simulated at relatively higher resolution (15-km) for selected periods in the Gulf of Tonkin and adjacent coastal areas. Simulation results are compared to MODIS cloud observations and local sound-ings obtained during 7SEAS for model verifications. Atmospheric boundary layer proc-esses are examined in relation to spatial and temporal variations of cloud fields. The cur-rent work serves as an important step toward improving our understanding of the effects of aerosol particles on maritime clouds. The detailed analysis will be presented at the conference.

HD 209458b in new light: evidence of nitrogen chemistry, patchy clouds and sub-solar water

NASA Astrophysics Data System (ADS)

MacDonald, Ryan J.; Madhusudhan, Nikku

2017-08-01

Interpretations of exoplanetary transmission spectra have been undermined by apparent obscuration due to clouds/hazes. Debate rages on whether weak H2O features seen in exoplanet spectra are due to clouds or inherently depleted oxygen. Assertions of solar H2O abundances have relied on making a priori model assumptions, for example, chemical/radiative equilibrium. In this work, we attempt to address this problem with a new retrieval paradigm for transmission spectra. We introduce poseidon, a two-dimensional atmospheric retrieval algorithm including generalized inhomogeneous clouds. We demonstrate that this prescription allows one to break vital degeneracies between clouds and prominent molecular abundances. We apply poseidon to the best transmission spectrum presently available, for the hot Jupiter HD 209458b, uncovering new insights into its atmosphere at the day-night terminator. We extensively explore the parameter space with an unprecedented 108 models, spanning the continuum from fully cloudy to cloud-free atmospheres, in a fully Bayesian retrieval framework. We report the first detection of nitrogen chemistry (NH3 and/or HCN) in an exoplanet atmosphere at 3.7-7.7σ confidence, non-uniform cloud coverage at 4.5-5.4σ, high-altitude hazes at >3σ and sub-solar H2O at ≳3-5σ, depending on the assumed cloud distribution. We detect NH3 at 3.3σ, and 4.9σ for fully cloudy and cloud-free scenarios, respectively. For the model with the highest Bayesian evidence, we constrain H2O at 5-15 ppm (0.01-0.03) × solar and NH3 at 0.01-2.7 ppm, strongly suggesting disequilibrium chemistry and cautioning against equilibrium assumptions. Our results herald a new promise for retrieving cloudy atmospheres using high-precision Hubble Space Telescope and James Webb Space Telescope spectra.

Lidar Cloud Detection with Fully Convolutional Networks

NASA Astrophysics Data System (ADS)

Cromwell, E.; Flynn, D.

2017-12-01

The vertical distribution of clouds from active remote sensing instrumentation is a widely used data product from global atmospheric measuring sites. The presence of clouds can be expressed as a binary cloud mask and is a primary input for climate modeling efforts and cloud formation studies. Current cloud detection algorithms producing these masks do not accurately identify the cloud boundaries and tend to oversample or over-represent the cloud. This translates as uncertainty for assessing the radiative impact of clouds and tracking changes in cloud climatologies. The Atmospheric Radiation Measurement (ARM) program has over 20 years of micro-pulse lidar (MPL) and High Spectral Resolution Lidar (HSRL) instrument data and companion automated cloud mask product at the mid-latitude Southern Great Plains (SGP) and the polar North Slope of Alaska (NSA) atmospheric observatory. Using this data, we train a fully convolutional network (FCN) with semi-supervised learning to segment lidar imagery into geometric time-height cloud locations for the SGP site and MPL instrument. We then use transfer learning to train a FCN for (1) the MPL instrument at the NSA site and (2) for the HSRL. In our semi-supervised approach, we pre-train the classification layers of the FCN with weakly labeled lidar data. Then, we facilitate end-to-end unsupervised pre-training and transition to fully supervised learning with ground truth labeled data. Our goal is to improve the cloud mask accuracy and precision for the MPL instrument to 95% and 80%, respectively, compared to the current cloud mask algorithms of 89% and 50%. For the transfer learning based FCN for the HSRL instrument, our goal is to achieve a cloud mask accuracy of 90% and a precision of 80%.

Cloud and Radiation Studies during SAFARI 2000

NASA Technical Reports Server (NTRS)

Platnick, Steven; King, M. D.; Hobbs, P. V.; Osborne, S.; Piketh, S.; Bruintjes, R.; Lau, William K. M. (Technical Monitor)

2001-01-01

Though the emphasis of the Southern Africa Regional Science Initiative 2000 (SAFARI-2000) dry season campaign was largely on emission sources and transport, the assemblage of aircraft (including the high altitude NASA ER-2 remote sensing platform and the University of Washington CV-580, UK MRF C130, and South African Weather Bureau JRA in situ aircrafts) provided a unique opportunity for cloud studies. Therefore, as part of the SAFARI initiative, investigations were undertaken to assess regional aerosol-cloud interactions and cloud remote sensing algorithms. In particular, the latter part of the experiment concentrated on marine boundary layer stratocumulus clouds off the southwest coast of Africa. Associated with cold water upwelling along the Benguela current, the Namibian stratocumulus regime has received limited attention but appears to be unique for several reasons. During the dry season, outflow of continental fires and industrial pollution over this area can be extreme. From below, upwelling provides a rich nutrient source for phytoplankton (a source of atmospheric sulphur through DMS production as well as from decay processes). The impact of these natural and anthropogenic sources on the microphysical and optical properties of the stratocumulus is unknown. Continental and Indian Ocean cloud systems of opportunity were also studied during the campaign. Aircraft flights were coordinated with NASA Terra Satellite overpasses for synergy with the Moderate Resolution Imaging Spectroradiometer (MODIS) and other Terra instruments. An operational MODIS algorithm for the retrieval of cloud optical and physical properties (including optical thickness, effective particle radius, and water path) has been developed. Pixel-level MODIS retrievals (11 km spatial resolution at nadir) and gridded statistics of clouds in th SAFARI region will be presented. In addition, the MODIS Airborne Simulator flown on the ER-2 provided high spatial resolution retrievals (50 m at nadir). These retrievals will be discussed and compared with in situ observations.

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 rates when mixed phase clouds are present.

Evaluating cloudiness in an AGCM with Cloud Vertical Structure classes and their radiative effects

NASA Astrophysics Data System (ADS)

Lee, D.; Cho, N.; Oreopoulos, L.; Barahona, D.

2017-12-01

Clouds are recognized not only as the main modulator of Earth's Radiation Budget but also as the atmospheric constituent carrying the largest uncertainty in future climate projections. The presentation will showcase a new framework for evaluating clouds and their radiative effects in Atmospheric Global Climate Models (AGCMs) using Cloud Vertical Structure (CVS) classes. We take advantage of a new CVS reference dataset recently created from CloudSat's 2B-CLDCLASS-LIDAR product and which assigns observed cloud vertical configurations to nine simplified CVS classes based on cloud co-occurrence in three standard atmospheric layers. These CVS classes can also be emulated in GEOS-5 using the subcolumn cloud generator currently paired with the RRTMG radiation package as an implementation of the McICA scheme. Comparisons between the observed and modeled climatologies of the frequency of occurrence of the various CVS classes provide a new vantage point for assessing the realism of GEOS-5 clouds. Furthermore, a comparison between observed and modeled cloud radiative effects according to their CVS is also possible thanks to the availability of CloudSat's 2B-FLXHR-LIDAR product and our ability to composite radiative fluxes by CVS class - both in the observed and modeled realm. This latter effort enables an investigation of whether the contribution of the various CVS classes to the Earth's radiation budget is represented realistically in GEOS-5. Making this new pathway of cloud evaluation available to the community is a major step towards the improved representation of clouds in climate models.

Global radiation maps by satellite climatologies. Exploring their diversity, including impacts attributed to clouds and ancillary data.

NASA Astrophysics Data System (ADS)

Raschke, Ehrhard; Kinne, Stefan

2010-05-01

The monitoring of decadal change for solar and infrared broadband radiation maps at the top of the atmosphere (ToA) and at the Earth's surface is a desirable tool to assess the overall impact of atmospheric change on climate. Satellite data going back to 1984 have been combined and interpreted to provide such decadal maps as part of the ISCCP and SRB projects. In addition, for the last ten years also maps linked to broadband radiation measurements by the CERES sensor have become available. Samples of time series and seasonal and monthly data of multi-annual averages are compared among the three data-sets. While there is reasonable agreement at the top of the atmosphere, there is increased diversity at the surface, as it requires accurate knowledge about atmospheric and environmental properties. Differences are largely driven by the assumed cloud properties. For instance, CERES clouds seem to cool the atmosphere, while ISCCP and SRB tend to heat the atmosphere. However, not only assumed cloud-properties but also ancillary data (e.g. aerosol, surface properties) need to be revisited, especially in the context of the planned ISCCP reprocessing.

Hot Jupiter with Hidden Water (Artist Concept)

NASA Image and Video Library

2016-06-08

Hot Jupiters, exoplanets around the same size as Jupiter that orbit very closely to their stars, often have cloud or haze layers in their atmospheres. This may prevent space telescopes from detecting atmospheric water that lies beneath the clouds, according to a study in the Astrophysical Journal. As much as half of the water in the atmospheres of these exoplanets may be blocked by these clouds or hazes, research suggests. The study, led by researchers at NASA's Jet Propulsion Laboratory, Pasadena, California, examined hot Jupiters that had been observed with the Hubble Space Telescope. http://photojournal.jpl.nasa.gov/catalog/PIA20687

Temporal Variations in Jupiter's Atmosphere

NASA Technical Reports Server (NTRS)

Simon-Miller, Amy A.; Chanover, N. J.; Yanamandra-Fisher, P.; Hammel, H. B.; dePater, I.; Noll, K.; Wong, M.; Clarke, J.; Sanchez-Levega, A.; Orton, G. S.;

flexCloud: Deployment of the FLEXPART Atmospheric Transport Model as a Cloud SaaS Environment

NASA Astrophysics Data System (ADS)

Morton, Don; Arnold, Dèlia

2014-05-01

FLEXPART (FLEXible PARTicle dispersion model) is a Lagrangian transport and dispersion model used by a growing international community. We have used it to simulate and forecast the atmospheric transport of wildfire smoke, volcanic ash and radionuclides. Additionally, FLEXPART may be run in backwards mode to provide information for the determination of emission sources such as nuclear emissions and greenhouse gases. This open source software is distributed in source code form, and has several compiler and library dependencies that users need to address. Although well-documented, getting it compiled, set up, running, and post-processed is often tedious, making it difficult for the inexperienced user. Our interest is in moving scientific modeling and simulation activities from site-specific clusters and supercomputers to a cloud model as a service paradigm. Choosing FLEXPART for our prototyping, our vision is to construct customised IaaS images containing fully-compiled and configured FLEXPART codes, including pre-processing, execution and postprocessing components. In addition, with the inclusion of a small web server in the image, we introduce a web-accessible graphical user interface that drives the system. A further initiative being pursued is the deployment of multiple, simultaneous FLEXPART ensembles in the cloud. A single front-end web interface is used to define the ensemble members, and separate cloud instances are launched, on-demand, to run the individual models and to conglomerate the outputs into a unified display. The outcome of this work is a Software as a Service (Saas) deployment whereby the details of the underlying modeling systems are hidden, allowing modelers to perform their science activities without the burden of considering implementation details.

Effects of Atmospheric Water Vapor and Clouds on NOAA (National Oceanic and Atmospheric Administration) AVHRR (Advanced Very High Resolution Radiometer) Satellite Data.

DTIC Science & Technology

1984-07-01

aerosols and sub pixel-sized clouds all tend to increase Channel 1 with respect to Channel 2 and reduce the computed VIN. Further, the Guide states that... computation of the VIN. Large scale cloud contamination of pixels, while diffi- cult to correct for, can at least be monitored and affected pixels...techniques have been developed for computer cloud screening. See, for example, Horvath et al. (1982), Gray and McCrary (1981a) and Nixon et al. (1983

Observed microphysical changes in Arctic mixed-phase clouds when transitioning from sea-ice to open ocean

NASA Astrophysics Data System (ADS)

Young, Gillian; Jones, Hazel M.; Crosier, Jonathan; Bower, Keith N.; Darbyshire, Eoghan; Taylor, Jonathan W.; Liu, Dantong; Allan, James D.; Williams, Paul I.; Gallagher, Martin W.; Choularton, Thomas W.

2016-04-01

The Arctic sea-ice is intricately coupled to the atmosphere[1]. The decreasing sea-ice extent with the changing climate raises questions about how Arctic cloud structure will respond. Any effort to answer these questions is hindered by the scarcity of atmospheric observations in this region. Comprehensive cloud and aerosol measurements could allow for an improved understanding of the relationship between surface conditions and cloud structure; knowledge which could be key in validating weather model forecasts. Previous studies[2] have shown via remote sensing that cloudiness increases over the marginal ice zone (MIZ) and ocean with comparison to the sea-ice; however, to our knowledge, detailed in-situ data of this transition have not been previously presented. In 2013, the Aerosol-Cloud Coupling and Climate Interactions in the Arctic (ACCACIA) campaign was carried out in the vicinity of Svalbard, Norway to collect in-situ observations of the Arctic atmosphere and investigate this issue. Fitted with a suite of remote sensing, cloud and aerosol instrumentation, the FAAM BAe-146 aircraft was used during the spring segment of the campaign (Mar-Apr 2013). One case study (23rd Mar 2013) produced excellent coverage of the atmospheric changes when transitioning from sea-ice, through the MIZ, to the open ocean. Clear microphysical changes were observed, with the cloud liquid-water content increasing by almost four times over the transition. Cloud base, depth and droplet number also increased, whilst ice number concentrations decreased slightly. The surface warmed by ~13 K from sea-ice to ocean, with minor differences in aerosol particle number (of sizes corresponding to Cloud Condensation Nuclei or Ice Nucleating Particles) observed, suggesting that the primary driver of these microphysical changes was the increased heat fluxes and induced turbulence from the warm ocean surface as expected. References: [1] Kapsch, M.L., Graversen, R.G. and Tjernström, M. Springtime atmospheric energy transport and the control of Arctic summer sea-ice extent. Nature Clim. Change 3, 744-748, doi:10.1038/nclimate1884 (2013) [2] Palm, S. P., Strey, S. T., Spinhirne, J., and Markus, T.: Influence of Arctic sea ice extent on polar cloud fraction and vertical structure and implications for regional climate. Journal of Geophysical Research (Atmospheres), 115, D21209, doi:10.1029/2010JD013900 (2010)

NASA's East and Southeast Asia Initiatives: BASE-ASIA and EAST-AIRE

NASA Technical Reports Server (NTRS)

Tsay, S.; Maring, H.

2005-01-01

Airborne dust from northern China influences air quality and regional climate in Asia during springtime. However, with the economic growth in China, increased emission of particulate air pollutants from industrial and vehicular sources will not only impact the earth's radiation balance, but also adversely affect human health year round. In addition, both of dust and aerosol pollutants can be transported swiftly across the Pacific affecting North America within a few days. Asian dust and pollutant aerosols can be detected by their colored appearance using current Earth observing satellites (e.g., MODIS, SeaWiFS, TOMS, etc.) and by sunphotometers deployed on the surface of the earth. Biomass burning has been a regular practice for land clearing and conversion in many countries, especially those in Africa, South America, and Southeast Asia. However, the climatology of Southeast Asia is very different than that of Africa and South America, such that large-scale biomass burning causes smoke to interact extensively with clouds during the peak-burning season of March to April. Globally significant sources of greenhouse gases (eg., CO2, CH4), chemically active gases (e.g., NO, CO, HC, CH3Br), and atmospheric aerosols are produced by biomass burning. These gases influence the Earth-atmosphere system, impacting both global climate and tropospheric chemistry. Some aerosols can serve as cloud condensation nuclei, which play a role in determining cloud lifetime and precipitation, altering the earth's radiation and water budgets. Biomass burning also affects the biogeochemical cycling of nitrogen and carbon compounds; the hydrological cycle; land surface reflectivity and emissivity; and ecosystem biodiversity and stability. Two NASA initiatives, EAST-AIRE (East Asian Study of Tropospheric Aerosols: an International Regional Experiment) and BASE-ASIA (Biomass-burning Aerosols in South East-Asia: Smoke Impact Assessment) will be presented. The objectives of these initiatives is to develop a better understanding of the impacts of aerosols on regional-to-global climate, hydrological and carbon cycles, and tropospheric chemistry.

Characterizing the Atmosphere of a Young Planet

NASA Technical Reports Server (NTRS)

Marley, Mark

2016-01-01

Since the discovery of the young, directly imaged planet 51 Eri b, its emergent spectrum has proved challenging to interpret. The initial discovery paper (Macintosh et al. 2015) interpreted the spectrum as indicative of a low mass (few Jupiter masses), effective temperature near 700 degrees Kelvin, and partial cloudiness. Subsequent observations in the K band, however, seem to invalidate the early models. In addition, newly improved photochemical data point to the likely presence of exotic haze species in the atmosphere. In my presentation I will explore the photochemistry of the atmosphere and discuss whether disequilibrium chemistry, hazes, clouds, or non-solar abundances of heavy elements may be responsible for the unusual spectrum of this planet. The implications for the interpretation of other young Jupiters in this mass and effective temperature range will also be considered.

Can Increased CO2 Levels Trigger a Runaway Greenhouse on the Earth?

NASA Astrophysics Data System (ADS)

Ramirez, R.

2014-04-01

Recent one-dimensional (globally averaged) climate model calculations suggest that increased atmospheric CO2 could conceivably trigger a runaway greenhouse if CO2 concentrations were approximately 100 times higher than today. The new prediction runs contrary to previous calculations, which indicated that CO2 increases could not trigger a runaway, even at Venus-like CO2 concentrations. Goldblatt et al. argue that this different behavior is a consequence of updated absorption coefficients for H2O that make a runaway more likely. Here, we use a 1-D cloud-free climate model with similar, up-to-date absorption coefficients, but with a self-consistent methodology, to demonstrate that CO2 increases cannot induce a runaway greenhouse on the modern Earth. However, these initial calculations do not include cloud feedback, which may be positive at higher temperatures, destabilizing Earth's climate. We then show new calculations demonstrating that cirrus clouds cannot trigger a runaway, even in the complete absence of low clouds. Thus, the habitability of an Earth-like planet at Earth's distance appears to be ensured, irrespective of the sign of cloud feedback. Our results are of importance to Earth-like planets that receive similar insolation levels as does the Earth and to the ongoing question about cloud response at higher temperatures.

Office of Naval Research (ONR), Arctic and Global Prediction Program Department Research Initiative (DRI), Sea State and Boundary Layer Physics of the Emerging Arctic Ocean Quantifying the Role of Atmospheric Forcing in Ice Edge Retreat and Advance Including Wind-Wave Coupling

DTIC Science & Technology

2014-09-30

direction Sea snake CIRES/NOAA sea-surface temperature 35-channel Radiometrics radiometer CIRES/NOAA PWV , LWP, profiles of T, q Ceilometer CIRES...size distribution Stabilized, scanning Doppler Lidar Leeds winds, cloud phase, turbulence HATPRO, scanning,12 ch radiometer Leeds PWV , LWP

Direct Imaging of a Cold Jovian Exoplanet in Orbit around the Sun-Like Star GJ 504

NASA Technical Reports Server (NTRS)

Kuzuhara, M.; Tamura, M.; Kudo, T.; Janson, M; Kandori, R.; Brandt, T. D.; Thalmann, C.; Spiegel, D.; Biller, B.; Carson, J.;

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuzuhara, M.; Tamura, M.; Kandori, R.

Several exoplanets have recently been imaged at wide separations of >10 AU from their parent stars. These span a limited range of ages (<50 Myr) and atmospheric properties, with temperatures of 800-1800 K and very red colors (J - H > 0.5 mag), implying thick cloud covers. Furthermore, substantial model uncertainties exist at these young ages due to the unknown initial conditions at formation, which can lead to an order of magnitude of uncertainty in the modeled planet mass. Here, we report the direct-imaging discovery of a Jovian exoplanet around the Sun-like star GJ 504, detected as part of themore » SEEDS survey. The system is older than all other known directly imaged planets; as a result, its estimated mass remains in the planetary regime independent of uncertainties related to choices of initial conditions in the exoplanet modeling. Using the most common exoplanet cooling model, and given the system age of 160{sup +350}{sub -60} Myr, GJ 504b has an estimated mass of 4{sup +4.5}{sub -1.0} Jupiter masses, among the lowest of directly imaged planets. Its projected separation of 43.5 AU exceeds the typical outer boundary of {approx}30 AU predicted for the core accretion mechanism. GJ 504b is also significantly cooler (510{sup +30}{sub -20} K) and has a bluer color (J - H = -0.23 mag) than previously imaged exoplanets, suggesting a largely cloud-free atmosphere accessible to spectroscopic characterization. Thus, it has the potential of providing novel insights into the origins of giant planets as well as their atmospheric properties.« less

Atmospheric System Research Marine Low Clouds Workshop Report, January 27-29,2016

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jensen, M.; Wang, J.; Wood, R.

Marine low clouds are a major determinant of the Earth?s albedo and are a major source of uncertainty in how the climate responds to changing greenhouse gas levels and anthropogenic aerosol. Marine low clouds are particularly difficult to simulate accurately in climate models, and their remote locations present a significant observational challenge. A complex set of interacting controlling processes determine the coverage, condensate loading, and microphysical and radiative properties of marine low clouds. Marine low clouds are sensitive to atmospheric aerosol in several ways. Interactions at microphysical scales involve changes in the concentration of cloud droplets and precipitation, which inducemore » cloud dynamical impacts including changes in entrainment and mesoscale organization. Marine low clouds are also impacted by atmospheric heating changes due to absorbing aerosols. The response of marine low clouds to aerosol perturbations depends strongly upon the unperturbed aerosol-cloud state, which necessitates greater understanding of processes controlling the budget of aerosol in the marine boundary layer. Entrainment and precipitation mediate the response of low clouds to aerosols but these processes also play leading roles in controlling the aerosol budget. The U.S. Department of Energy Atmospheric Radiation Measurement (ARM) Climate Research Facility and Atmospheric System Research (ASR) program are making major recent investments in observational data sets from fixed and mobile sites dominated by marine low clouds. This report provides specific action items for how these measurements can be used together with process modeling to make progress on understanding and quantifying the key cloud and aerosol controlling processes in the next 5-10 years. Measurements of aerosol composition and its variation with particle size are needed to advance a quantitative, process-level understanding of marine boundary-layer aerosol budget. Quantitative precipitation estimates that combine radar and lidar measurements are becoming available, and these could be used to test process models, quantify precipitation responses to aerosol, and constrain climate models. Models and observations can be used to constrain how clouds respond dynamically to changing precipitation. New measurements of turbulence from ground-based remote sensing could be used to attempt to relate entrainment to the vertical and horizontal structure of turbulence in the boundary layer. Cloud-top entrainment plays a major role in modulating how low clouds respond to both aerosols and to greenhouse gases, so investment in promising new observational estimates would be beneficial. Precipitation formation and radiative cooling both help marine low clouds to organize on the mesoscale. More work is needed to develop metrics to characterize mesoscale organization, to elucidate mechanisms that determine the type and spatial scale of mesoscale cellular convection, and to understand the role of mesoscale structures in the stratocumulus-to-cumulus transition.« less

Scattering in infrared radiative transfer: A comparison between the spectrally averaging model JURASSIC and the line-by-line model KOPRA

NASA Astrophysics Data System (ADS)

Griessbach, Sabine; Hoffmann, Lars; Höpfner, Michael; Riese, Martin; Spang, Reinhold

2013-09-01

The viability of a spectrally averaging model to perform radiative transfer calculations in the infrared including scattering by atmospheric particles is examined for the application of infrared limb remote sensing measurements. Here we focus on the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) aboard the European Space Agency's Envisat. Various spectra for clear air and cloudy conditions were simulated with a spectrally averaging radiative transfer model and a line-by-line radiative transfer model for three atmospheric window regions (825-830, 946-951, 1224-1228 cm-1) and compared to each other. The results are rated in terms of the MIPAS noise equivalent spectral radiance (NESR). The clear air simulations generally agree within one NESR. The cloud simulations neglecting the scattering source term agree within two NESR. The differences between the cloud simulations including the scattering source term are generally below three and always below four NESR. We conclude that the spectrally averaging approach is well suited for fast and accurate infrared radiative transfer simulations including scattering by clouds. We found that the main source for the differences between the cloud simulations of both models is the cloud edge sampling. Furthermore we reasoned that this model comparison for clouds is also valid for atmospheric aerosol in general.

The effect of clouds on the earth's radiation balance

NASA Technical Reports Server (NTRS)

Herman, G. F.; Wu, M. L. C.; Johnson, W. T.

1979-01-01

The effect of global cloudiness on the radiation balance at the top of the atmosphere is studied in general circulation model experiments. Wintertime simulations were conducted with clouds that had realistic optical properties, and were compared with simulations in which the clouds were transparent to either solar or thermal radiation. Clouds increase the net balance by limiting longwave loss to space, but decrease it by reflecting solar radiation. It is found that the net result of cloudiness is to maintain net radiation which is less than would be realized under clear conditions: Clouds cause the net radiation at the top of the atmosphere to increase due to longwave absorption, but to decrease even more due to cloud reflectance of solar radiation.

High Vertically Resolved Atmospheric State Revealed with IASI Single FOV Retrievals under All-weather Conditions

NASA Technical Reports Server (NTRS)

Zhou, Daniel K.; Liu, Xu; Larar, Allen M.; Smith, William L.; Taylor, Jonathan P.; Schluessel, L. Peter; Strow, Larrybee; Mango, Stephen A.

2008-01-01

The Infrared Atmospheric Sounding Interferometer (IASI) on the MetOp satellite was launched on October 19, 2006. The Joint Airborne IASI Validation Experiment (JAIVEx) was conducted during April 2007 mainly for validation of the IASI on the MetOp satellite. IASI possesses an ultra-spectral resolution of 0.25 cm(exp -1) and a spectral coverage from 645 to 2760 cm(exp -1). Ultra-spectral resolution infrared spectral radiance obtained from near nadir observations provide atmospheric, surface, and cloud property information. An advanced retrieval algorithm with a fast radiative transfer model, including cloud effects, is used for atmospheric profile and cloud parameter retrieval. Preliminary retrievals of atmospheric soundings, surface properties, and cloud optical/microphysical properties with the IASI observations are obtained and presented. These retrievals are further inter-compared with those obtained from airborne FTS system, such as the NPOESS Airborne Sounder Testbed - Interferometer (NAST-I), dedicated dropsondes, radiosondes, and ground based Raman Lidar. The capabilities of satellite ultra-spectral sounder such as the IASI are investigated to benefit future NPOESS operation.

Sensitivity analysis of upwelling thermal radiance in presence of clouds

NASA Technical Reports Server (NTRS)

Subramanian, S. V.; Tiwari, S. N.; Suttles, J. T.

1981-01-01

Total upwelling radiance at the top of the atmosphere is evaluated theoretically in the presence of clouds. The influence of cloud heights, thicknesses and different cloud covers on the upwelling radiance is also investigated. The characteristics of the two cloud types considered in this study closely correspond to altocumulus and cirrus with the cloud emissivity as a function of its liquid water (or ice) content. For calculation of the integrated transmittance of atmospheric gases such as, H2O, CO2, O3, and N2O, the Quasi Random Band (QRB) model approach is adopted. Results are obtained in three different spectral ranges and are compared with the clearsky radiance results. It is found that the difference between the clearsky and cloudy radiance increases with increasing cloud height and liquid water content. This difference also decreases as the surface temperature approaches the value of the cloud top temperature.

The Impact of Aerosols on Cloud and Precipitation Processes: Cloud-Resolving Model Simulations

NASA Technical Reports Server (NTRS)

Tao, Wei-Kuo; Li, X.; Khain, A.; Simpson, S.

2005-01-01

Cloud microphysics are inevitable affected by the smoke particle (CCN, cloud condensation nuclei) size distributions below the clouds, Therefore, size distributions parameterized as spectral bin microphysics are needed to explicitly study the effect of atmospheric aerosol concentration on cloud development, rainfall production, and rainfall rates for convective clouds. Recently, a detailed spectral-bin microphysical scheme was implemented into the the Goddard Cumulus Ensemble (GCE) model. The formulation for the explicit spectral-bim microphysical processes is based on solving stochastic kinetic equations for the size distribution functions of water droplets (i.e., cloud droplets and raindrops), and several types of ice particles [i.e., pristine ice crystals (columnar and plate-like), snow (dendrites and aggregates), graupel and frozen drops/hail]. Each type is described by a special size distribution function containing many categories (i.e., 33 bins). Atmospheric aerosols are also described using number density size-distribution functions.

Stability of the Early Mars Atmosphere to Collapse into Permanent Polarcaps

NASA Technical Reports Server (NTRS)

Haberle, R. M.; Kahre, M. A.; Wordsworth, R.; Forget, F.

2016-01-01

The presence of a permanent CO2 polar ice cap on Mars has important consequences for the planet's climate system. The heat balance of such a cap, which is determined mainly by atmospheric heat transport, and the downward solar in infrared radiative fluxes, determines its surface temperature, which through the vapor pressure relation sets the mean annual surface pressure. On Mars today, for example, the south residual CO2 cap is present year-round with a mean annual temperature of approximately 145 K which corresponds to a mean annual CO2 vapor pressure of approximately 600 Pa. On early Mars, permanent polar caps are also possible especially since the sun was less luminous 3.5-4.0 Gya. Thus, the existence of permanent polar caps on early Mars is central to understanding the nature of the planets climate system in those ancient times and whether or not the atmosphere might have been capable of sustaining conditions suitable for liquid water flowing over the surface as is indicated in the geological record. Forget et al [1] showed that for present orbital properties atmospheric collapse into permanent polar caps could only be prevented for surface pressures roughly between 500 - 3000 hPa. Though follow-on studies confirm and extend the Forget et al. results [2], the full sensitivity of this "window" of stability has not been explored. There are many factors to consider such the albedo of the caps, dust content of the atmosphere, and the presence of water ice clouds. However, we begin our exploration of the stability of the early Martian atmosphere by focusing on the role of CO2 ice clouds. In some preliminary simulations with the Ames Mars General Circulation Model (GCM) we found that atmospheric collapse depends on assumptions regarding the fate of CO2 ice clouds. If, for example, we assume the clouds immediately fall to the surface, then in some cases collapse is favored. On the other hand if the clouds are allowed to fall and evaporate, collapse can be averted. This implies that CO2 ice cloud microphysics is important to the overall stability of the atmosphere. Though the Ames GCM has a sophisticated CO2 cloud microphysics package that includes nucleation, growth, and sedimentation (see accompanying poster by Kahre et al. [3]), we have implemented a simpler scheme based on the Forget et al. [1] approach to CO2 ice clouds. Our goal is to reproduce and expand their study. The key parameter in this approach is the concentration and vertical distribution of cloud condensation nuclei (CCN), i.e., dust particles. Fewer CCN lead to larger particles which fall faster, while higher CCN concentrations lead to smaller particles and thicker clouds that remain suspended for longer periods of time. We plan to explore the stability of the atmosphere to CCN concentrations and distributions and then assess the capability of thick early atmospheres to loft and distribute dust particles (CCN) around the planet. Thus, our work will shed light on the nature of the coupling between the dust and CO2 cycles and the implications it has for the early Mars climate system.

The Exoplanet Cloud Atlas

NASA Astrophysics Data System (ADS)

Gao, Peter; Marley, Mark S.; Morley, Caroline; Fortney, Jonathan J.

2017-10-01

Clouds have been readily inferred from observations of exoplanet atmospheres, and there exists great variability in cloudiness between planets, such that no clear trend in exoplanet cloudiness has so far been discerned. Equilibrium condensation calculations suggest a myriad of species - salts, sulfides, silicates, and metals - could condense in exoplanet atmospheres, but how they behave as clouds is uncertain. The behavior of clouds - their formation, evolution, and equilibrium size distribution - is controlled by cloud microphysics, which includes processes such as nucleation, condensation, and evaporation. In this work, we explore the cloudy exoplanet phase space by using a cloud microphysics model to simulate a suite of cloud species ranging from cooler condensates such as KCl/ZnS, to hotter condensates like perovskite and corundum. We investigate how the cloudiness and cloud particle sizes of exoplanets change due to variations in temperature, metallicity, gravity, and cloud formation mechanisms, and how these changes may be reflected in current and future observations. In particular, we will evaluate where in phase space could cloud spectral features be observable using JWST MIRI at long wavelengths, which will be dependent on the cloud particle size distribution and cloud species.

Planets of the solar system. [Jupiter and Venus

NASA Technical Reports Server (NTRS)

Kondratyev, K. Y.; Moskalenko, N. I.

1978-01-01

Venera and Mariner spacecraft and ground based radio astronomy and spectroscopic observations of the atmosphere and surface of venus are examined. The composition and structural parameters of the atmosphere are discussed as the basis for development of models and theories of the vertical structure of the atmosphere, the greenhouse effect, atmospheric circulation and cloud cover. Recommendations for further meteorological studies are given. Ground based and Pioneer satellite observation data on Jupiter are explored as well as calculations and models of the cloud structure, atmospheric circulation and thermal emission field of Jupiter.

Stability relationship for water droplet crystallization with the NASA Lewis icing spray

NASA Technical Reports Server (NTRS)

Marek, C. John; Bartlett, C. Scott

1987-01-01

In order to produce small droplets for icing cloud simulation, high pressure air atomizing nozzles are used. For certain icing testing applications, median drop sizes as small as 5 mm are needed, which require air atomizing pressures greater than 3000 kPa. Isentropic expansion of the ambient temperature atomizing air to atmospheric pressure can result in air stream temperatures of -160 C which results in ice crystals forming in the cloud. To avoid such low temperatures, it is necessary to heat the air and water to high initial temperatures. An icing spray research program was conducted to map the temperatures below which ice crystals form. A soot slide technique was used to determine the presence of crystals in the spray.

Studies for the Loss of Atomic and Molecular Species from Io

NASA Technical Reports Server (NTRS)

Smyth, William H.

1998-01-01

Updated neutral emission rates for electron impact excitation of atomic oxygen and sulfur based upon the Collisional Radiative Equilibrium (COREQ) model have been incorporated in the neutral cloud models. An empirical model for the Io plasma torus wake has also been added in the neutral cloud model to describe important enhancements in the neutral emission rates and lifetime rates in this spatial region. New insights into Io's atmosphere and its interaction with the plasma torus are discussed. These insights are based upon an initial comparison of simultaneous lo observations on October 14, 1997, for [0I] 6300 Angstrom emissions acquired by groundbased facilities and several ultraviolet emissions acquired by HST/STIS in the form of high-spatial- resolution images for atomic oxygen and sulfur.

Ultra-Stable Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research (5STAR)

NASA Technical Reports Server (NTRS)

Dunagan, Stephen E.; Johnson, Roy R.; Redemann, Jens; Holben, Brent N.; Schmidt, Beat; Flynn, Connor Joseph; Fahey, Lauren; LeBlanc, Samuel; Liss, Jordan; Kacenelenbogen, Meloe S.;