Publication Abstracts
Wood et al. 2017
Wood, R., J.D. Stemmler,
, and A. Jefferson, 2017: Low CCN concentration air masses over the eastern North Atlantic: Seasonality, meteorology and drivers. J. Geophys. Res. Atmos., 122, no. 2, 1203-1223, doi:10.1002/2016JD025557.A 20 month cloud condensation nucleus concentration (NCCN) dataset from Graciosa Island (39°N, 28°W) in the remote North Atlantic is used to characterize air masses with low cloud condensation nuclei (CCN) concentrations. Low-CCN events are defined as 6 h periods with mean NCCN < 20 cm-3 (0.1% supersaturation). A total of 47 low-CCN events are identified. Surface, satellite, and reanalysis data are used to explore the meteorological and cloud context for low-CCN air masses. Low-CCN events occur in all seasons, but their frequency was 3 times higher in December-May than during June-Noember. Composites show that many of the low-CCN events had a common meteorological basis that involves southerly low-level flow and rather low wind speeds at Graciosa. Anomalously low pressure is situated to the west of Graciosa during these events, but back trajectories and lagged SLP composites indicate that low-CCN air masses often originate as cold air outbreaks to the north and west of Graciosa. Low-CCN events were associated with low cloud droplet concentrations (Nd) at Graciosa, but liquid water path (LWP) during low-CCN events was not systematically different from that at other times. Satellite Nd and LWP estimates from MODIS collocated with Lagrangian back-trajectories show systematically lower Nd and higher LWP several days prior to arrival at Graciosa, consistent with the hypothesis that observed low-CCN air masses are often formed by coalescence scavenging in thick warm clouds, often in cold air outbreaks.
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BibTeX Citation
@article{wo01100l, author={Wood, R. and Stemmler, J. D. and Rémillard, J. and Jefferson, A.}, title={Low CCN concentration air masses over the eastern North Atlantic: Seasonality, meteorology and drivers}, year={2017}, journal={Journal of Geophysical Research: Atmospheres}, volume={122}, number={2}, pages={1203--1223}, doi={10.1002/2016JD025557}, }
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RIS Citation
TY - JOUR ID - wo01100l AU - Wood, R. AU - Stemmler, J. D. AU - Rémillard, J. AU - Jefferson, A. PY - 2017 TI - Low CCN concentration air masses over the eastern North Atlantic: Seasonality, meteorology and drivers JA - J. Geophys. Res. Atmos. JO - Journal of Geophysical Research: Atmospheres VL - 122 IS - 2 SP - 1203 EP - 1223 DO - 10.1002/2016JD025557 ER -
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