Research Highlights

Double Bonus: Win-Win for Atmospheric Particles
Nov 18, 2014       
It’s a slam dunk for scientists measuring atmospheric particle properties. Typically calculated from their chemical composition and size distribution data, the larger particles often escape characterization. Scientists at Pacific Northwest National Laboratory and the University of Colorado developed a new method that simultaneously connects two critical properties: real refractive index, a measure of how much [...]

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Observing Warm Clouds in 3D Using ARM Scanning Cloud Radars and a Novel Ensemble Method
Nov 05, 2014       
Boundary-layer clouds make a significant contribution to the planetary albedo and thus are fundamentally important to the Earth’s radiation budget. Due to their complex turbulent structures, coupled with a strong susceptibility to aerosol, they remain a key source of uncertainty in climate projections. While Atmospheric Radiation Measurement Climate Research Facility (ARM)’s long-term observations from vertically [...]

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Validation of Climate Model Ice Cloud Properties
Oct 31, 2014       
General circulation models are used for understanding the past, present, and future climate. To be able to project future climate it is important that models provide a realistic depiction of the physical processes. Researchers at the National Center for Atmospheric Research (NCAR) have recently addressed how well properties of ice particles are represented in the [...]

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Fast and Rigorous: Finding Surface Reflectivity by Looking Up at Clouds
Oct 28, 2014       
Capturing sunlight reflected off the Earth's surface and bounced off a cloud back to the Earth is an effective measure of surface reflectivity—or surface albedo, the measure of how mirror-like the Earth's surface is. Researchers at Pacific Northwest National Laboratory developed a new way to measure surface albedo by capturing that cloud-bounced sunlight. In collaboration [...]

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Dust Takes Detour on Ice-Cloud Journey
Oct 15, 2014       
Wrapped in pollution, dust diverts from its usual course and steers clear of water. Researchers at Pacific Northwest National Laboratory found the result closes one more gap in understanding how and when cloud ice crystals form. They found that dust, usually a primary catalyst encouraging ice formation, when modified by pollution from combustion, becomes less [...]

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Interactions Between Cumulus Convection and Its Environment as Revealed by MC3E
Oct 13, 2014       
After decades of effort, accurately representing cumulus convection is still one of the most challenging tasks for weather and climate modeling. This is primarily because the interaction between cumulus convection and its environment has not been fully understood. Previous budget diagnostic studies have often targeted tropical convective systems given the dominant role these convective systems [...]

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First Observations of Tracking Clouds Using Scanning ARM Cloud Radars
Oct 05, 2014       
Scanning cloud radars provide new opportunities to map clouds and their evolution. Specifically, these radars observe cloud particles well in advance of large droplet formation, while also capturing the clouds at spatial and temporal scales sufficient for continuous tracking algorithms. To better demonstrate the capabilities of the new Scanning ARM Cloud Radars (SACR) at the [...]

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Validation of CERES-MODIS Cloud Retrievals Using the Azores Data
Sep 26, 2014       
Marine boundary layer (MBL) cloud properties derived for the National Aeronautics and Space Administration (NASA) Clouds and the Earth's Radiant Energy System (CERES) Project using Terra and Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) data are compared with observations taken at the ARM Mobile Facility at the Azores (AMF-Azores) site from June 2009 through December 2010. [...]

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Diurnal Variation of MBL Cloud Properties over the Azores
Sep 26, 2014       
For the single-layered marine boundary layer (MBL) cloud microphysical properties, Dong, Xi, and Wu (2014) provided the diurnal variations of cloud liquid water path (LWP) and liquid water content (LWC). However, they only presented the daytime LWP, LWC, cloud-droplet effective radius (re), number concentration (Nd), and cloud optical depth (τ), as well as surface measured [...]

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Effects of Sea Spray on the Thermodynamics of the Hurricane Boundary Layer
Sep 24, 2014       
The effects of sea spray on surface fluxes under strong winds is usually attributed to surface layer dynamics in the vicinity of the ocean surface. We propose that the main effects of sea spray on surface fluxes and intensity of hurricanes are related to the microphysical effects of spray drops penetrating deep convective clouds in [...]

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A New Theory of Time-dependent Freezing and Its Application to Investigation of Formation of Hail
Sep 24, 2014       
A new theory of wet growth of hail takes into account the inhomogeneities of surface temperature and of liquid film over the surface of the particle and parameterizes effects of non-sphericity of hail particles on their growth by accretion (Figure 1a). The time-dependent process of raindrop freezing as well as freezing of accreted water by [...]

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Turn Trash Into Treasure: Continental Warm Cloud Properties Derived from Unexploited Solar Background Signals
Sep 20, 2014       
Low-altitude boundary layer clouds strongly influence global climate through their impact on Earth’s radiation and hydrological cycle. Therefore, long-term global measurements are crucial for providing direct observational constraints to improve our knowledge of cloud and precipitation formation, and to better represent these clouds in weather and climate models. At the Atmospheric Radiation Measurement [...]

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Growing More Effective Ways to Measure Climate Change
Sep 17, 2014       
Life on earth depends on the movement of carbon dioxide through the environment. Plants take it in through photosynthesis, people and animals breath it out, the burning of fossils fuels sends it back into the atmosphere. According to the U.S. Environmental Protection Agency, in 2012, carbon dioxide accounted for about 82% of all greenhouse gas [...]

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Deciphering Raindrop Collisions with Dual-polarization Radar
Sep 01, 2014       
As raindrops descend to the surface, they undergo a variety of collisions with one another. These collisions can lead to coalescence of the drops into a larger one, breakup of the colliding drops into small fragments, or can be inconsequential. These processes affect the evolution of the drop size distribution (DSD), ultimately influencing the potential [...]

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