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Peng, QH, Xie SP, Wang DX, Zheng XT, Zhang H.  2019.  Coupled ocean-atmosphere dynamics of the 2017 extreme coastal El Nino. Nature Communications. 10   10.1038/s41467-018-08258-8   AbstractWebsite

In March 2017, sea surface temperatures off Peru rose above 28 degrees C, causing torrential rains that affected the lives of millions of people. This coastal warming is highly unusual in that it took place with a weak La Nina state. Observations and ocean model experiments show that the downwelling Kelvin waves caused by strong westerly wind events over the equatorial Pacific, together with anomalous northerly coastal winds, are important. Atmospheric model experiments further show the anomalous coastal winds are forced by the coastal warming. Taken together, these results indicate a positive feedback off Peru between the coastal warming, atmospheric deep convection, and the coastal winds. These coupled processes provide predictability. Indeed, initialized on as early as 1 February 2017, seasonal prediction models captured the extreme rainfall event. Climate model projections indicate that the frequency of extreme coastal El Nino will increase under global warming.

Park, HS, Xie SP, Son SW.  2013.  Poleward stationary eddy heat transport by the Tibetan Plateau and equatorward shift of westerlies during northern winter. Journal of the Atmospheric Sciences. 70:3288-3301. AbstractWebsite

The orographic effect of the Tibetan Plateau on atmospheric poleward heat transport is investigated using an atmospheric general circulation model. The linear interference between the Tibetan Plateau-induced winds and the eddy temperature field associated with the land-sea thermal contrast is a key factor for enhancing the poleward stationary eddy heat transport. Specifically, Tibetan Plateau-induced stationary waves produce northerlies over the cold eastern Eurasian continent, leading to a poleward heat transport. In another hot spot of stationary eddy heat transport over the eastern North Pacific, Tibetan Plateau-induced stationary waves transport relatively warm marine air northward.In an experiment where the Tibetan Plateau is removed, the poleward heat transport is mostly accomplished by transient eddies, similar to the Southern Hemisphere. In the presence of the Tibetan Plateau, the enhanced stationary eddy heat transport is offset by a comparable reduction in transient eddy heat transport. This compensation between stationary and transient eddy heat transport is seen in observed interannual variability. Both the model and observations indicate that an enhanced poleward heat transport by stationary waves weakens transient eddies by decreasing the meridional temperature gradient and the associated westerlies in midlatitudes.

Pahnke, K, Sachs JP, Keigwin L, Timmermann A, Xie SP.  2007.  Eastern tropical Pacific hydrologic changes during the past 27,000 years from D/H ratios in alkenones. Paleoceanography. 22   10.1029/2007pa001468   Abstract