An inverse relationship between aggregate northern hemisphere tropical cyclone activity and subsequent winter climate

Our understanding of the climate role of tropical cyclones (TCs) remains incomplete despite increasing efforts to quantify it. TCs cool the sea surface over a large area, transport heat vertically and meridionally, and dry the tropical atmosphere. Following an anomalous TC season, when TCs have done an anomalous share of energy transport, there may be alterations of other climate mechanisms. Accordingly, a robust inverse relationship between northern hemisphere (NH) TC activity and NH winter climate is explored here. Specifically, aggregate power dissipation index for NH Pacific recurving TCs is the current optimal predictor (r = -0.57; p < 0.01) of NH winter stationary meridional temperature flux. TC-winter climate causality would not only argue for an elevated climate role of TCs, but would present an autumn predictability barrier given the limited skill in forecasting seasonal TC activity details. A proxy relationship would suggest undiagnosed coupled climate mechanisms that have control over both the tropics and extratropics. Citation: Hart, R. E. (2011), An inverse relationship between aggregate northern hemisphere tropical cyclone activity and subsequent winter climate, Geophys. Res. Lett., 38, L01705, doi:10.1029/2010GL045612.