Research Highlights

Understanding Changes in Cloud Phase Partitioning in Mixed-phase Clouds: an Arctic Case Study
Aug 22, 2016       
“A low cloud of water and ice – in Barrow, Alaska, how nice. Its structure was measured with ease – but why did the ice phase decrease?” For a springtime low-level mixed-phase stratiform cloud case from Barrow, Alaska, a unique combination of instruments and retrieval methods is combined with multiple modeling perspectives to determine key processes [...]

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Towards Retrieving Critical Relative Humidity from Ground-based Remote-sensing Observations
Aug 16, 2016       
In a Global Circulation Model (GCM), cloud should form before the grid-box-mean state becomes saturated. Therefore, assumptions about sub-grid variability in temperature and water vapour are necessary, which are typically combined in the critical relative humidity (RHcrit), the relative humidity at which cloud forms a sub-saturated GCM grid box.

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Impact of External Industrial Sources on the Regional and Local SO2 and O3 Levels of the Mexico Megacity
Aug 09, 2016       
Scientists determined how strongly various emissions sources affected air quality in different areas of the Mexico City Metropolitan Area.

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MAGIC Ship-based Observations Help Validate Satellite Microwave Liquid Water Path
Aug 04, 2016       
Satellite-based passive microwave (MW) liquid water path (LWP) is a fundamental quantity for climate studies, climate model validation, and validation of satellite visible/near-infrared retrievals over the oceans. Unfortunately, the lack of independent observations has prevented the evaluation of MW LWP, and thus the accuracy of satellite MW-derived LWP remains uncertain. The ship deployment of the [...]

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The Python ARM Radar Toolkit, the World's Leading Interactive Radar Toolkit
Aug 04, 2016       
Weather radars provide an abundant source of data related to the conditions present in the atmosphere. The Python ARM Radar Toolkit (Py-ART) allows scientists to effectively work with this data and extract scientific insights from these large data sets. Py-ART is used for analysis of weather radar data using established routines available in the [...]

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The Spectroscopic Foundation of Radiative Forcing of Climate by Carbon Dioxide
Jul 21, 2016       
We explored the state-of-the-science of how rising atmospheric CO2 concentrations warm the climate system through radiative forcing caused by spectroscopic absorption features. We found that uncertainties in the absorption line parameters and understanding of the shape of CO2 lines, both of which are important for CO2 radiative forcing, are much smaller than the actual forcing.

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Field Testing the Next-Generation of Radiosondes
Jul 21, 2016       
During 3-8 June 2014, an intercomparison study of Vaisala radiosondes RS92 (the current ARM instrumentation) and RS41 (next generation) was undertaken at the ARM SGP site. The results indicate that the sounding measurements generally agree well within manufactured-defined uncertainties with notable exceptions when exiting liquid cloud layers where evaporative cooling impacts are mitigated for the [...]

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Trace Gas Removal by Deep Convective Storms
Jul 20, 2016       
Deep convective storms have a large impact on the climate by sending atmospheric trace gases high into the atmosphere where they participate in particle formation and ozone formation that affect the amount of sunlight, or radiative energy, that passes through the atmosphere to Earth’s surface. Understanding how storms, or convective systems, transport trace-gas concentrations to [...]

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Observing the Amazon: the Role of Time and Place in Cloud Measurements
Jul 20, 2016       
Research led by Department of Energy scientists at Pacific Northwest National Laboratory laid the groundwork for future explorations of the Green Ocean Amazon, GOAmazon, 2014/15 field campaign data sets by documenting the variability in space and time of deep convection around the field campaign surface sites distributed upwind and downwind of Manaus, Brazil. Understanding the [...]

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Capturing Biogenic Volatile Organic Compounds in a Coupled-Model System Compared to Observation
Jul 20, 2016       
Current climate models still have large uncertainties in estimating biogenic (naturally emitted) trace gases, which can significantly affect atmospheric chemistry and secondary aerosol formation that ultimately influence the capacity of aerosol particles to affect Earth’s energy balance (aerosol radiative forcing) and air quality. These uncertainties result from many factors, including uncertainties in land-surface processes (exchanges [...]

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Hiding in Plain Sight: a Less-Explored Secret of Secondary Organic Aerosols
Jul 19, 2016       
More than 50% of the fine atmospheric aerosol particle mass is often comprised of organic aerosols, most of which are secondary organic aerosols (SOA), formed by atmospheric oxidation of organic gases. Recent measurements suggest that a major fraction of SOA has volatility that is orders of magnitude lower than previously assumed. It is important to [...]

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Getting Cloud Ice from Pollution
Jul 19, 2016       
Atmospheric soot (black carbon) particles absorb solar energy to warm the atmosphere—yet high in the atmosphere they may instigate cloud ice formation. But when these particles mix with other aerosols and compounds in the atmosphere, their ice-forming (ice-nucleating) ability suffers, thus altering the properties of pure ice clouds (cirrus), vital for their impact to moderate [...]

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Three Dimensions Are Better Than Two, When It Comes to Representing Aerosols
Jul 19, 2016       
A research team led by scientists at Pacific Northwest National Laboratory developed a novel three-dimensional particle representation for aerosol modeling. This new add-on solves for particle size, the amount of black carbon in the particle, and the ability of the particle to draw moisture, or hygroscopicity. All three attributes are needed to accurately estimate how [...]

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ARM Azores Observations Help Identify Deficiencies in Climate Model Simulations of Low Clouds
Jul 16, 2016       
The correctness of low-cloud representation in climate models is crucial to climate change projections and needs to be comprehensively evaluated.

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Pollution from a Megacity in the Amazon: the Case of Manaus, Brazil
Jul 12, 2016       
This special journal issue outlines the Observations and Modeling of the Green Ocean Amazon (GoAmazon2014/5) Experiment. The field campaign research sought to quantify how aerosol and cloud life cycles in a clean background in the tropics are influenced by pollutant outflow from a large tropical city. The team used ground-based research sites and aircraft measurement [...]

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Two-Column Aerosol Project: Impact of Elevated Particle Layers on Particle Optical Depth
Jul 11, 2016       
A group of DOE-funded scientists on an ARM field campaign discovered elevated levels of aerosols even on Cape Cod's cloud-free days—and these aerosols have a large impact on the amount of sunlight reaching the surface. The year-long study included measurements to examine the chemical composition of the particles, the way they reflect or scatter light, [...]

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Fall Speeds of Cirrus Crystals Faster Than Expected
Jul 11, 2016       
The fall speeds of high cirrus cloud crystals depend upon crystal mass, for which no direct measurements exist. Based on new measurements of crystal images, calculated mass yields fall speeds as a function of maximum particle dimension that are, surprisingly, roughly twice as large as derived in the most commonly used past studies.

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Sub-micrometre Particulate Matter Is Primarily in Liquid Form over Amazon Rain Forest
Jul 07, 2016       
A team of scientists, including U.S. Department of Energy-funded researchers, found that particles with diameters smaller than 1 μm are primarily in liquid form over the tropical rainforest of central Amazonia, where the relative humidity is greater than 80% more than 70% to 80% of the time during the dry and wet seasons. These findings are [...]

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Urban Emissions Significantly Enhance SOA Production at a Rural Site in the NE US
Jun 12, 2016       
During our study, we observed that aerosol concentration and composition at a rural site in the Northeastern U.S. were influenced strongly by upwind urban emissions. A possible reason is that anthropogenic pollutants advected from urban areas interacted with biogenic emissions in the rural region and led to a substantial enhancement of secondary organic aerosol production.

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