Research Highlights

Assessing Aerosol Impacts on Drizzle Intensity and Frequency from AMF Data
Apr 12, 2014       
Aerosols have a strong effect on climate through their potential to modify the properties of warm clouds. An increase in aerosol loading could reduce drizzle production; modulate the stability of the boundary layer; and change cloud properties, lifetime, and extent, which is referred to as the second aerosol indirect effect. Recent studies showed that global [...]

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Madden–Julian Oscillation Heating: to Tilt or Not to Tilt
Apr 10, 2014       
It is hypothesized that specific cloud populations at different stages are essential to the initiation and maintenance of the Madden-Julian Oscillation (MJO). In particular, the occurrence of shallow convection that then transitions to mid-level convection before the active phase of the MJO is thought to provide lower-level heating that then promotes large-scale moisture convergence necessary [...]

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Observational Analysis of Land-Atmosphere Coupling for Climate Model Evaluation
Apr 08, 2014       
The state of the land can influence surface energy and moisture fluxes, boundary-layer clouds, and regional convection and precipitation, especially in summer when it couples more intensely with the atmosphere. Therefore, investigations of the cloud life cycle over continents need to consider the role played by land-atmosphere interactions. Coarse-resolution global climate models tend to simulate a [...]

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Multi-scale Variations of Decade-long Cloud Fractions from Six Different Platforms over the SGP
Mar 31, 2014       
For decades, researchers have intensively studied observationally based cloud fraction estimates to better understand current climate change and predict future climate variability. In this study, observationally based cloud fraction estimates from six different platforms (three ground-based estimates and three satellite-based estimates) are compared.

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Retrieving Thermodynamic Profiles in the Boundary Layer in Clear and Cloudy Conditions
Mar 22, 2014       
The thermodynamic structure of the atmospheric boundary layer (BL; the lowest 1-3 km of the atmosphere) rapidly changes due to a wide range of processes, and many studies require accurate profiles of temperature and water vapor at high time-resolution in order to understand the processes at work in the BL. These profiles can be derived [...]

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Understanding the Differences Between Absolution Calibration Techniques in the Microwave
Mar 22, 2014       
Microwave radiometers (MWRs) typically measure downwelling radiation between 22 and 60 GHz. The most common geophysical variable derived from these observations are liquid water path and precipitable water vapor. However, if the MWR measures radiation at several frequencies along the 22.2 GHz water vapor line (e.g., from 22.2 to 25.0 GHz) and also several frequencies [...]

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Arctic Winter Frost Flowers Have Negligible Influence on Cloud Longwave Warming
Mar 19, 2014       
Frost flowers are clusters of highly saline ice crystals growing on newly formed sea ice or frozen lakes. They wick brine from the surface of sea ice, and typically last about a few days after the initial formation and then are buried by snow, sublimate as sea ice grows thicker, or are blown away by [...]

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A Revealing Look Inside Northern Australian Wet Season Precipitation
Mar 07, 2014       
Significant wet season rainfall over Darwin stems from precipitation having distinct forcing and life cycle characteristics, and these behaviors may be reflected in the longer-term observed ARM precipitation records. For example, the deeper convection that propagates over Darwin is often continental in origin, whereas shallow convection is often more maritime. Previous studies note that much [...]

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MBL Cloud Properties Derived from the Azores-AMF Observations
Mar 04, 2014       
Between June 2009 and December 2010, at the ARM Azores site, a 19-month record of total, single-layered low (< 3 kilometers), middle (3-6 kilometers), and high (> 6 kilometers) cloud fractions (CFs), and the single-layered marine boundary layer (MBL) cloud macrophysical and microphysical properties was generated from ground-based measurements. This is the most comprehensive data [...]

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The Organic Molecules Explaining New Particle Growth in the Boreal Forest
Mar 04, 2014       
The growth of newly formed particles from sizes of less than three nanometers up to the sizes of cloud condensation nuclei (about one hundred nanometers) in many continental ecosystems require abundant, essentially non-volatile organic vapours. However, the sources and compositions of such vapors were previously unknown. This research found that ozonolysis of monoterpenes, a [...]

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Arctic Multilayered Mixed-phase Cloud Processes
Feb 19, 2014       
Over the North Slope of Alaska, researchers used cloud radar Doppler velocity spectra, lidar backscattering coefficients and depolarization ratios, and aircraft in situ measurements to investigate microphysical processes occurring in a case of multilayered, mixed-phase clouds.

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Measured Parameterization of Fire Aerosol Single Scattering Albedo Using Combustion Efficiency
Feb 03, 2014       
Biomass burning (BB) is one of the largest sources of carbonaceous aerosols that are known to affect the radiative balance of the Earth (Bond et al. 2013). The net BB radiative forcing is small (0.0 ± 0.20Wm 2) (IPCC 2013), but very uncertain, due to the need to resolve the balance between the positive forcing [...]

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