Effects of the Atlantic Multidecadal Oscillation on Panama Canal Watershed Precipitation

The Atlantic Multidecadal Oscillation (AMO) is an index of North Atlantic sea-surface temperature variability with a quasi-periodicity of 60-80 years. The AMO has been shown to substantially affect precipitation across the Northern Hemisphere and in parts of the Southern Hemisphere. A high quality long-term record of measured precipitation in the Panama Canal Watershed (PCW) provides a unique opportunity for the examination of the effects of the AMO on precipitation in Central America. Twenty-one precipitation stations located in the PCW have recorded precipitation for 50 or more years, with two extending to almost 130 years. An analysis of these data show that the AMO is strongly correlated with multidecadal oscillations in annual precipitation in the PCW. The AMO is especially correlated with monthly precipitation during the beginning and end of the 8-month rainy season (May to December). The precipitation record also indicates the influence of the El Niño Sothern Oscillation (ENSO). The PCW is responsible for supplying all of the water necessary for the operation of the Panama Canal, as well as the water needed by over 1 million Panamanians. During the last two major El Niño events (1997/8 and 2015/6), the supply was insufficient resulting in shipping restrictions during the Dry Seasons of 1998 and 2016. Because of increased consumptive use of PCW water, forecasting of water availability in the PCW can be aided by increased understanding and consideration of influential climate oscillations such as the AMO.