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Measurements and Modeling of Black-Carbon Aerosols in the Arctic

Bambha, Ray B.; LaFranchi, Brian L.; Schrader, Paul E.; Lucero, Daniel A.; Ivey, Mark D.; Michelsen, Hope A.

We have made the first continuous measurements of black carbon in Barrow, Alaska at the ARM aerosol- observing site at the NOAA Barrow Observatory using a Single-Particle Soot Photometer (SP2). These data demonstrate that BC particles are extremely small, and a majority of the particles (by number density) are smaller than 0.5 fg, the lower limit of reliability of the SP2. We developed the first numerical model capable of quantitatively reproducing the laser-induced incandescence (LII) and scattering signals produced by the SP2, the industry-standard BC instrument. Our model reproduces the SP2 signal temporally and spectrally and demonstrates that the current SP2 optical design allows substantial contamination of LII on the scattering signal. We ran CAM5-SE in nudged mode, i.e., by constraining the transport used in the model with meteorological data. The results demonstrate the problem observed previously of under-predicting BC at high latitudes. The cause of the discrepancy is currently unknown, but we suspect that it is associated with scavenging and rainout mechanisms.

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TYPE SAND Report YEAR 2016
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Monitoring Understanding and Predicting the Growth of Methane Emissions in the Arctic

Bambha, Ray B.; LaFranchi, Brian L.; Schrader, Paul E.; Roesler, Erika L.; Taylor, Mark A.; Lucero, Daniel A.; Ivey, Mark D.; Michelsen, Hope A.

Concern over Arctic methane (CH 4 ) emissions has increased following recent discoveries of poorly understood sources and predictions that methane emissions from known sources will grow as Arctic temperatures increase. New efforts are required to detect increases and explain sources without being confounded by the multiple sources. Methods for distinguishing different sources are critical. We conducted measurements of atmospheric methane and source tracers and performed baseline global atmospheric modeling to begin assessing the climate impact of changes in atmospheric methane. The goal of this project was to address uncertainties in Arctic methane sources and their potential impact on climate by (1) deploying newly developed trace-gas analyzers for measurements of methane, methane isotopologues, ethane, and other tracers of methane sources in the Barrow, AK, (2) characterizing methane sources using high-resolution atmospheric chemical transport models and tracer measurements, and (3) modeling Arctic climate using the state-of-the-art high- resolution Spectral Element Community Atmosphere Model (CAM-SE).

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TYPE SAND Report YEAR 2016
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29 Results
29 Results