Twentieth century dust lows and the weakening of the westerly winds over the Tibetan Plateau

• Published in: Geophysical research letters 2015-04, Vol.42 (7), p.2434-2441
• Main Authors: Grigholm, B., Mayewski, P. A., Kang, S., Zhang, Y., Morgenstern, U., Schwikowski, M., Kaspari, S., Aizen, V., Aizen, E., Takeuchi, N., Maasch, K. A., Birkel, S., Handley, M., Sneed, S.
• Format: Article
• Language: English
• Subjects: 20th century; Archives & records; atmospheric circulation; atmospheric dust; Atmospheric models; Atmospheric particulates; Atmospheric pressure; Atmospherics; Barometric pressure; Calcium; Climate; climate proxy; Cores; Dust; Dust storms; Entrainment; glaciochemistry; Gradients; High resolution; Ice; Ice cores; Meteorological data; Meteorology; paleoclimate; Plateaus; Pressure gradients; Strength; Temperature; Temperature effects; Transport; Transportation models; Trends; Variability; Westerlies; Wind; Wind speed; Wind velocities; Wind velocity; Winds
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1002/2015GL063217

Understanding past atmospheric dust variability is necessary to put modern atmospheric dust into historical context and assess the impacts of dust on the climate. In Asia, meteorological data of atmospheric dust is temporally limited, beginning only in the 1950s. High‐resolution ice cores provide the ideal archive for reconstructing preinstrumental atmospheric dust concentrations. Using a ~500 year (1477–1982 A.D.) annually resolved calcium (Ca) dust proxy from a Tibetan Plateau (TP) ice core, we demonstrate the lowest atmospheric dust concentrations in the past ~500 years during the latter twentieth century. Declines in late nineteenth to twentieth century Ca concentrations significantly correspond with regional zonal wind trends from two reanalysis models, suggesting that the Ca record provides a proxy for the westerlies. Twentieth century warming and attendant atmospheric pressure reductions over northern Asia have potentially reduced temperature/pressure gradients resulting in lower zonal wind velocities and associated dust entrainment/transport in the past ~500 years over the TP. Key Points Five hundred year calcium dust proxy was established from a Tibetan Plateau ice core Calcium and zonal wind correlations suggest a proxy for westerly wind strength Atmospheric dust and westerly strength are anomalously low in the twentieth century