News Center

Bimodal CCN Spectra
May 23, 2015 [ Research Highlights ]       
Aerosol spectra under marine stratus are often bimodal and attributable to cloud processes. Sizes at the minima between the modes have inferred supersaturations (S) of nearby clouds (Hoppel et al. 1985, 1994). This was based on the principle that the lower critical S (Sc) particles that produced cloud droplets were increased by 1) chemical reactions [...]

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Sleepless on the Great Plains
May 22, 2015 [ Feature Stories and Releases ]       
In an effort to understand why the rain in the Great Plains falls mainly in the dark, more than 100 researchers and dozens of support staff will spend 25 sleepless nights on the ground and in the air this summer as part of the Plains Elevated Convection at Night (PECAN) field campaign. The ARM Facility will support this campaign from June 1 to July 15 through the Southern Great Plains site and an array of instrumentation.

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Pierre Gentine and Yunyan Zhang Selected Early Career Research Program
May 19, 2015 [ Facility News ]       
Two ARM Facility users and Atmospheric System Research program researchers were selected for the U.S. Department of Energy's Early Career Research Program (ECRP). Pierre Gentine, from Columbia University in New York, and Yunyan Zhang from Lawrence Livermore National Laboratory were among the 44 nationwide recipients awarded this funding opportunity that supports the development of individual [...]

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Flynn, Schmid Receive NASA Group Achievement Award
May 18, 2015 [ Facility News ]       
ARM Aerial Facility Technical Director Beat Schmid and ARM Aerosol Working Group Translator Connor Flynn received the prestigious 2015 National Aeronautics and Space Administration (NASA) Group Achievement Award. The award recognized the collaborative team from the NASA field campaign Studies of Emissions and Atmospheric Composition, Clouds, and Climate Coupling by Regional Surveys (SEAC4RS) deployed during [...]

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Pilot Phase Begins for Routine Large-Eddy Simulations
May 15, 2015 [ Facility News, Feature Stories and Releases ]       
Researchers target observation and modeling together for a new level of scientific analysis on climate When it comes to clouds, the Earth’s energy budget, and tiny aerosols, scientists don’t have all the answers. However, each atmospheric model improvement brings them a small step closer. A team of U.S. Department of Energy (DOE) scientists, led by William [...]

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Land, Sea, and Air: ACAPEX Targets Atmospheric Rivers
May 13, 2015 [ Feature Stories and Releases ]       
After six weeks of gathering data from air and sea in California, scientists are back on dry land ready to examine their findings. The team, led by Ruby Leung at Pacific Northwest National Laboratory, chased and sampled a total of four atmospheric rivers that made landfall in northern California during ARM Cloud Precipitation Experiment (ACAPEX).

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2015 William T. Pecora Award Nominations
May 12, 2015 [ Facility News ]       
Nominations for the 2015 William T. Pecora Award are currently being accepted through June 15. This award is presented annually to individuals or groups that have made outstanding contributions toward understanding the Earth using remote sensing. Individuals from public and private sector, teams, organizations, and professional societies are eligible. Both national and international nominations [...]

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Assessing Impact of Shattered Artifacts on Measured Size Distributions
May 12, 2015 [ Research Highlights ]       
Model parameterizations of ice clouds have typically been derived from observations of ice particle size distributions (PSDs), collected by optical array probes, mounted on the wings of aircraft. Many recent studies have shown PSDs can potentially be contaminated by particles shattering on the tips of these probes, with shattered artifacts subsequently entering the probe sample [...]

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Characterizing Uncertainties in Ice Particle Size Distributions
May 10, 2015 [ Research Highlights ]       
In many parameterization schemes for numerical models or remote sensing retrievals, particle size distributions (SDs) are represented by gamma functions. Empirical relations, determined from in-situ measurements of SDs, are sometimes needed to determine how the parameters of the gamma function (slope lambda, intercept N0 and shape factor mu) depend on environmental conditions such as temperature, [...]

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The Shapes and Phases of Small Particles in Mixed-Phase Clouds
May 10, 2015 [ Research Highlights ]       
Mixed-phase clouds, in which supercooled water droplets and ice crystals co-exist, are ubiquitous throughout the troposphere over all regions of the Earth, and especially over polar regions. Because these clouds are radiatively significant, because radiative properties depend significantly on particle phase, and because particles with maximum dimensions D < 60 micrometers contribute up to [...]

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Single Particle Database of Natural Ice Crystals: Dimensions and Aspect Ratios
May 09, 2015 [ Research Highlights ]       
Accurate knowledge of dimensions and of length (L)–width (W) relationships for ice crystals is important because it is needed to construct shape models for calculating the single-scattering (e.g., scattering phase function and asymmetry parameter) and microphysical (e.g., area and fall velocity) properties of ice crystals. Prior studies have shown that the assumed L–W relationship impacts [...]

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Making Sense of Convective Updrafts: Mass Flux and Microphysics
May 07, 2015 [ Research Highlights ]       
Cloud-resolving and large-eddy simulation results are often used to inform convective parameterization development for climate models simply owing to the fact that, in theory, all aspects of a simulated system are known. However, high-resolution model simulations contain a variety of complex dynamical structures that often do not map directly to the structural elements of convective [...]

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New MICROBASE Ensemble Data Set Available
Apr 28, 2015 [ Data Announcements ]       
A new data set of ensemble cloud retrievals from the March 2000 intensive observational period at the Southern Great Plains Central Facility is now available in the ARM Data Archive evaluation area. The new data set uses the baseline cloud microphysical algorithm, known as MICROBASE, along with a variance-based method that varies the empirical parameters [...]

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Navigation Best Estimate Value-Added Product Released
Apr 27, 2015 [ Data Announcements ]       
Developed in response to the first ship-based deployment of the second ARM Mobile Facility (AMF2), the Navigation Best Estimate (NAVBE) Value-Added Product (VAP) has been released for evaluation. Meteorological, cloud, and aerosol measurements were collected during nearly 20 round trips of the container ship, Horizon Spirit, between Los Angeles, CA, and Honolulu, HI, from September [...]

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Developing and Evaluating Ice Cloud Parameterizations by Combining Radar and in Situ Observations
Apr 22, 2015 [ Research Highlights ]       
One of the main challenges to measure ice clouds by remote sensing is that the transfer functions which relate the observables (e. g., radar Doppler spectrum) to cloud properties (e. g., ice water content, or IWC) are not uniquely defined. To overcome this challenge, this study has two main objectives: 1) estimate a mass-size relation [...]

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AmeriFlux and Methane Evaluation VAP Now Available for Barrow Data
Apr 21, 2015 [ Data Announcements ]       
Greenhouse gases (GHGs) are suspected to be key drivers of global climate change. As Arctic permafrost melts, it unlocks stored carbon, which may contribute to large increases in the atmospheric mixing ratios of these gases. Understanding the rates and controlling mechanisms of these releases is of great importance for climate prediction and modeling. The ARM Climate [...]

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First Ever ARM / ASR Joint User Facility PI Meeting
Apr 21, 2015 [ Facility News ]       
A recent joint meeting of the users and staff from the Atmospheric Radiation Measurement (ARM) Climate Research Facility and principal investigators from the Atmospheric System Research (ASR) program provided invaluable input on scientific priorities, needs, and gaps to the ARM Facility, as well as insight into ASR research and scientific progress. This first ever joint [...]

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Light Absorption of Primary Organic Aerosol Paper Named ACS Editors' Choice
Apr 20, 2015 [ Research Highlights ]       
Organic aerosols (OAs) in the atmosphere affect Earth’s energy budget by not only scattering but also absorbing solar radiation due to the presence of the so-called “brown carbon” (BrC) component. However, the absorptivities of OAs are not represented or are poorly represented in current climate and chemical transport models. Most models still treat primary OA [...]

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The Two Faces of Aerosols
Apr 15, 2015 [ Research Highlights ]       
It's a double dose of climate disturbance. Tiny particles of pollution—also known as aerosols—both cool and warm the planet. Now, a team of scientists from Pacific Northwest National Laboratory and NASA identified how current climate models may be far off in estimating the actual amounts of these particles and their total impact on the atmosphere. [...]

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Intersecting Cold Pools: Convective Cloud Organization by Cold Pools over Tropical Ocean
Apr 06, 2015 [ Research Highlights ]       
As rain drops descend to the surface, they can evaporate and cool the air. The cold air then spreads horizontally and forms pools at the surface that displace surrounding warm air. The dynamics of cold pools are an important mechanism of organizing convection. Researchers, including Department of Energy scientists at Pacific Northwest National Laboratory, [...]

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Comparison of Vertical Velocities in Cirrus Derived from Aircraft and Ground-based Radar
Mar 31, 2015 [ Research Highlights ]       
Vertical velocities and turbulence in the upper troposphere are key elements affecting the microphysical properties and dynamical evolution of cirrus clouds. In particular, vertical velocities contribute to the cooling rates in the upper troposphere thereby affecting the values of ice supersaturations, the number concentrations of ice crystals formed by ice nucleation, and the growth rates [...]

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Satellite Inference of Thermals and Cloud Base Updraft Speeds
Mar 30, 2015 [ Research Highlights ]       
Thermals transfer and distribute heat, moisture, momentum, and pollutant materials from the surface layer to the upper part of the convective mixed layer. Thermals also play a central role in the formation of convective clouds and precipitation. Cloud base updrafts govern water vapor supersaturation there, determining the concentration of cloud condensation nuclei (CCN) activated into [...]

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Are Increases in Thunderstorm Activity in Southeast China Related to Air Pollution?
Mar 12, 2015 [ Research Highlights ]       
Pollution aerosols are thought to have an invigorative effect on convective clouds by suppressing warm precipitation in moist and convectively unstable environments. As clouds develop to above the freezing level, mixed-phase clouds containing ice and supercooled water can grow further more readily and induce cloud electrification and thunderstorms during summertime. In southeastern China, the summer [...]

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Strongly Absorbing Aerosols Affect Retrievals of Cloud Optical Depth
Mar 12, 2015 [ Research Highlights ]       
Surface-based and satellite remote sensing techniques have proven indispensable for learning more about cloud temporal and spatial variations. Comparisons between cloud properties retrieved from surface and spaceborne platforms are commonly done as a way of validating satellite retrievals. Observations made at the surface are often treated as the “ground-truth” with respect to satellite retrievals. Both [...]

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Filling Gaps Within Instrument Records
Mar 09, 2015 [ Research Highlights ]       
The ARM SGP site in Lamont, Oklahoma, is home to one of the longest records of actively sensed cloud information anywhere on the planet. Despite the best efforts of the program, instruments occasionally misbehave or are taken down for maintenance, resulting in holes within this record. Utilizing the Active Remote Sensing of Clouds Value-Added Product [...]

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Quantifying the Importance of Cold Pool Mechanisms for Convection Triggering
Mar 09, 2015 [ Research Highlights ]       
The organization of the subcloud layer into cold pools, areas of evaporatively cooled downdraft air spreading on the surface, is one of the key processes that help sustainin deep convection. It has long been known cold pools can spawn new convective cells by mechanically lifting air along their gust front. Such lifting could be the [...]

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Modeling Precipitating Cumulus Congestus Observed by the ARM Radar Suite During the MC3E Field Campaign
Mar 04, 2015 [ Research Highlights ]       
Much of the uncertainty in climate model projections stems from the limited understanding of cloud and precipitation processes and the parameterization of these processes in global climate models (GCMs). Typically, results from cloud-resolving models (CRMs) or large-eddy simulation (LES) models serve as benchmarks for developing and tuning single-column models (SCMs), which, in turn, form the [...]

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Evaluation of Trigger Functions for Convective Parameterization Schemes
Mar 03, 2015 [ Research Highlights ]       
In a convective parameterization scheme, the trigger function activates the onset of convection. Hence, an accurate trigger function is important to the correct simulation of convection in global climate models (GCMs). However, the formulation of trigger functions in many of convective schemes is ad hoc and convection is often activated too easily. The over-activation of [...]

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