08 May 2015

Influence of El Niño on Dust over the Atlantic Ocean

Summary

El Niño–the warming of the ocean surface off the coast of Peru in the December/January timeframe occurring every 3 to 5 years–affects the weather across the world. A new study by a team of scientists at Scripps Institute of Oceanography and Pacific Northwest National Laboratory have identified a previously unknown effect on dust over the Atlantic Ocean. During those northern hemisphere summers, when El Niño is in its opposite phase (La Niña), a 150-year climate simulation by the Community Earth System Model suggests that westward winds over North Africa are stronger than usual. The team found that stronger winds produce, and carry, more dust over the Atlantic Ocean than during the El Niño phase of the oscillation. However, this relationship is complicated by another mode of variability called the North Atlantic Oscillation, which varies on time scales of decades. Although the interfering oscillation makes it difficult for researchers to confirm these results with direct measurements of dust, they found there is good agreement between the simulated and observed data.

Contact
Michael J DeFlorio
Scripps Institution of Oceanography (SIO)
Publications
DeFlorio, MJ, ID Goodwin, DR Cayan, AJ Miller, SJ Ghan, DW Pierce, LM Russell, and B Singh.  2015.  "Interannual Modulation of Subtropical Atlantic Boreal Summer."  Climate Dynamics, doi:10.1007/s00382-015-2600-7.
Acknowledgments

This study forms a portion of the Ph.D. dissertation of M.J.D. Funding was provided by NSF (AGS-1048995), and by the U.S. Department of Energy, Office of Science, Decadal and Regional Climate Prediction using Earth System Models (EaSM program). Battelle Memorial Institute operates the Pacific Northwest National Laboratory for the DOE under contract DE-AC06-76RLO Fig. 19 Scatterplot of JJA standardized leading principal components of tropical Pacific SST variability and JJA downstream North Africa dust AOD anomalies (top row) and 700 hPa zonal wind anomalies (bottom row) on the most negative (left column) and least negative (right column) sliding correlation periods in CESM M. J. DeFlorio et al. 1 3 1830. We are grateful for the contribution made by Joseph M. Prospero (RSMAS, U. Miami), who provided us with the Barbados dust record. We also acknowledge Cynthia Twohy (NorthWest Research Associates and SIO) and Diego Melgar (UC-Berkeley) for improving the manuscript, and for assistance with the pseudo-principal component spectral analysis used in this study. Our CESM simulation can be accessed via an email inquiry (mdeflori@ucsd.edu).