Influence of eastern Pacific and central Pacific El Ni\~no events on winter climate extremes over the eastern and central United States

Abstract

Different influences of the eastern-Pacific (EP) El Ni\~no and central-Pacific (CP) El Ni\~no on nine winter extreme indices over the eastern and central United States are examined through composite analysis of high-resolution daily maximum temperature, minimum temperature, and precipitation for the period 1950–2010. During EP El Ni\~no winters, there are usually more warm days and warm nights, fewer frost days, cold days, and cold nights over the eastern and central United States than in winters with a CP El Ni\~no, especially for the Ohio Valley, around the Great Lakes, and southern New England. For precipitation extremes, compared with CP El Ni\~no, EP El Ni\~no usually brings more extreme precipitation amounts, more days with large precipitation amounts, larger amounts of maximum consecutive 5-day total precipitation, and a shorter duration of consecutive dry days around the Great Lakes and Ohio Valley. The 500 hPa geopotential height anomalies show that wave train patterns differ when the maximum tropical sea surface heating locations are displaced. The corresponding wind field and moisture convergence anomalies are examined to analyse the mechanisms that drive the anomaly fields associated with the two types of El Ni\~no events.