News Center

Students to Attend ARM Summer Training Event
Jul 06, 2015 [ Facility News ]       
Twenty-six students from around the world have been chosen to attend the upcoming ARM Summer Training and Science Applications event. From July 15-24 at the National Weather Center in Norman, Oklahoma, the graduate and postdoctoral students will gain practical and theoretical knowledge about observing and modeling aerosols, clouds, and precipitation processes. The training is sponsored [...]

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Up, Up, and Away!
Jul 06, 2015 [ Feature Stories and Releases ]       
This summer, researchers are launching an unprecedented number of weather balloons in rural Oklahoma to collect data to help improve how weather and climate models predict the diurnal cycle of rainfall and cloud development.

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Call for Abstracts for AGU Fall Meeting and AMS Annual Meeting
Jul 02, 2015 [ Events ]       
The abstract submission deadlines are 5 August for the American Geophysical Union (AGU) Fall Meeting and early August for the American Meteorological Society (AMS) Annual Meeting. AGU Sessions The largest meeting in the world for Earth and space science is open for abstract submissions. The AGU Fall Meeting takes place in San Francisco, California, on 14-18 December [...]

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Clearer Skies for Cloud Modeling
Jul 01, 2015 [ Facility News ]       
This May, Cyril Morcrette was awarded the L F Richardson Prize by the Royal Meteorological Society for his work in evaluating cloud forecasts. Although weather and climate models often rely on different metrics to make accurate forecasts, Morcrette created a unified methodology that can be used to evaluate cloud predictions at both scales. Data provided [...]

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Stereo Photogrammetry Reveals Substantial Drag on Cloud Thermals
Jun 25, 2015 [ Research Highlights ]       
Fast updrafts within clouds can generate hail, lightning, and tornadoes at the surface, as well as clear-air turbulence that pose hazards for aircraft aloft. Despite these important impacts of fast updrafts, there is surprisingly large uncertainty about the forces that generate these updraft speeds. For example, do these cloud updrafts experience drag? If so, what [...]

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Sticky Thermals: Evidence for a Dominant Balance Between Buoyancy and Drag in Cloud Updrafts
Jun 25, 2015 [ Research Highlights ]       
Quickly rising clouds are associated with many important phenomena, including hail, turbulence, and lightning. But, what sets the speeds of these rising clouds? In other words, what is the balance of forces giving rise to the observed cloud updraft speeds? Here, we answer this question by studying thousands of cloud thermals in a high-resolution large-eddy [...]

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But First, Public Relations
Jun 22, 2015 [ Blog, Field Notes, PECAN ]       
This past week, members of the University of Oklahoma (OU) and National Severe Storms Laboratory’s (NSSL) Boundary Layer Integrated Sensing and Simulation (BLISS) research team embarked on a seven-week long field campaign, PECAN. Principal investigator Dave Turner, NSSL, is directing the team in studying mesoscale convective systems, convective initiation, lower-atmosphere gravity waves, and low-level jets. [...]

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Regime Analysis to Identify the Contribution of Clouds to Surface Temperature Errors in GCMs
Jun 16, 2015 [ Research Highlights ]       
Many Global Circulation Models (GCMs) exhibit a persistent bias in the 2m-temperature (T2m) over the midlatitude continents, present in weather forecasts and climate simulations. A number of hypotheses have been proposed, from deficiencies in the soil-vegetation-atmosphere energy exchange, to poorly resolved boundary-layer clouds to misrepresentations of deep convection. This paper presents a new method to [...]

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Life in the PECAN Operations Center
Jun 12, 2015 [ Blog, Field Notes, PECAN ]       
I have spent the first week of PECAN in the operations center serving as the coordinator of the fleet of mobile vehicles that provide remotely sensed profiles of temperature, humidity, and winds. Here is an excerpt of a typical day’s work… To set the stage: PECAN has four different but related scientific foci, and each [...]

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North to Alaska: Researchers Rush to Understand Warming Trend
Jun 08, 2015 [ Facility News, Feature Stories and Releases ]       
ARM-ACME V field campaign makes first science flight June 4 A group of scientists from the Atmospheric Measurement Research (ARM) Climate Research Facility won’t be looking for gold or oil this summer as they crisscross Alaska’s North Slope in an airplane. Instead, the ARM Airborne Carbon Measurements V (ARM-ACME V) team—led by Sebastien Biraud from U.S. [...]

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New Science Board Members Tackle ARM’s Expanding Landscape
Jun 08, 2015 [ Facility News ]       
With facilities around the world hosting field campaigns on a regular basis, the ARM Climate Research Facility continues to be an important resource to the scientific community. Thanks to the vigilance of the ARM Science Board, the ARM Facility is able to support quality science with over 70 campaigns a year. Comprised of highly-respected scientists from [...]

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BAMS Features Results of 21-Month ARM Deployment
Jun 01, 2015 [ Facility News ]       
Featured in the March 2015 Bulletin of the American Meteorological Society (BAMS), the 21-month ARM mobile facility deployment in the Azores was the longest of its type in a non-tropical marine environment. This data set collected during the Clouds, Aerosols, and Precipitation in the Marine Boundary Layer (CAP-MBL) field campaign provided valuable insights into the [...]

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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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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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