Research Highlights

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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Chamber Studies Uncover New Pathways for Atmospheric Aerosol Growth
May 31, 2016       
The first few hours following the formation of a new atmospheric aerosol particle are a competition between the growth of the particle due to the condensation of low volatility “sticky” gases and the loss of the particle by collisions with other aerosol particles. New observations from the Cosmics Leaving Outdoor Droplets (CLOUD) chamber at CERN [...]

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Spiraling Through a Storm
May 26, 2016       
A multi-sensor effort that blends observations from UND Citation aircraft spirals and ground-based ARM scanning precipitation and cloud radars to investigate the signatures associated with riming and aggregation processes.

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On the Impacts of Different Definitions of Maximum Dimension for Nonspherical Cloud Particles
May 25, 2016       
Knowledge of ice crystal particle size distributions (PSDs) is critical for development of microphysical parameterization schemes for numerical models and remote-sensing retrieval algorithms. Two-dimensional in situ images captured by cloud-imaging probes on aircraft are widely used to derive PSDs in term of maximum particle dimension (Dmax). However, inconsistencies in the definition of Dmax used in [...]

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Isoprene Photochemistry over the Amazon Rainforest
May 24, 2016       
Isoprene is a biogenic volatile organic compound that, when oxidized by sunlight, heavily influences atmospheric chemistry over forested areas. Using field measurements from the ground and the air, this paper tracked the fate of isoprene over the central Amazon for eight weeks during the wet season. The main research site, 70 kilometers downwind of the [...]

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Regime Dependence of Cloud Water Variability Observed at the ARM Sites
May 11, 2016       
Observations from ARM sites across the world have improved our understanding of how the amount of water in clouds varies at small scales. Based on these observations, a new way of describing how cloud water varies with cloud regime has been developed for use in global weather and climate models.

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Microphysical Piggybacking: Understanding the Coupling Between Cloud Dynamics and Microphysics
May 08, 2016       
A novel modeling approach was developed to clearly document the impact of cloud microphysics (i.e., the model representation of growth and fallout of cloud and precipitation particles) on cloud simulations. A traditional approach is to perform parallel simulations with different microphysics schemes or scheme parameters. In such parallel simulations, clearly separating physical impacts from merely [...]

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Diagnosing Raindrop Evaporation, Breakup, and Coalescence in Vertical Radar Observations
Apr 27, 2016       
In our quest to better understand precipitating cloud systems, we must realize that radars do not directly observe microphysical processes. Rather, radars observe raindrops and the changes in the number and size of those observed raindrops over time and space provide us with clues to the microphysical processes acting upon those raindrops. Thus, evaporation and [...]

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Quasi-Vertical Profiles – a New Way to Look at Polarimetric Radar Data
Apr 26, 2016       
A novel methodology is introduced for processing and presenting polarimetric radar data collected by scanning weather radars. It involves azimuthal averaging of polarimetric radar variables at high antenna elevation and presenting resulting quasi-vertical profiles (QVPs) in a height-versus-time format.

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Saggy Bright Bands
Apr 26, 2016       
A new technique for viewing radar observations allows for analyzing the evolution of the melting layer “bright band,” a signature associated with melting snowflakes. Radar and aircraft data demonstrate that transient bright band sagging provides information about the ice particles falling into the layer from above.

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Dependence of Entrainment in Shallow Cumulus Convection on Vertical Velocity and Distance to Cloud Edge
Apr 17, 2016       
How entrainment rates of shallow cumuli depend on environmental conditions is quantified by applying a novel Lagrangian tracking analysis on the response of shallow cumuli to an imposed small large-scale temperature perturbation, leading to a simple formulation that relates entrainment rates to vertical velocity and distance to cloud edge (or cloud size).

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The Midlatitude Continental Convective Clouds Experiment (MC3E)
Apr 11, 2016       
The DOE ARM Climate Research Facility and the NASA Global Precipitation Measurement (GPM) satellite mission collaborated for the 2011 Midlatitude Continental Convective Clouds Experiment (MC3E) to collect ground- and aircraft-based measurements characterizing the four-dimensional properties of convective storms at the Southern Great Plains. Over the course of the six-week campaign, a number of storms were [...]

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Birth and Growth of an Aerosol
Apr 06, 2016       
Tiny atmospheric aerosols are some of the most highly studied particles connected with Planet Earth, yet questions remain on how they are formed and how they affect climate. Now Pacific Northwest National Laboratory scientists have developed new approaches to accurately model the birth and growth of these important aerosols. "Most atmospheric climate models either neglect [...]

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