Asymmetric responses of Land Hydroclimatology to Two types of El Niño in the Mississippi River Basin
Abstract
El Niño events play important roles in influencing the hydroclimatology over the Mississippi River Basin (MRB). This study shows that the two types of El Niño events, the central Pacific (CP) El Niño and eastern Pacific (EP) El Niño, have opposite effects on spring soil water hydrology in the MRB. Above-normal spring (March) precipitation during EP El Niño years leads to higher soil water levels during the subsequent 2 to 3 months in the central and western MRB. On the other hand, CP El Niño events induce below-normal spring precipitation that causes lower soil water levels over the Ohio-Mississippi Valley during the following 1 or 2 months. As a result, a springtime asymmetric response occurs in the MRB streamflow and soil water storage to the two types of El Niño. Subsurface hydrological storage processes are found to be essential to extend El Niño's influence in the MRB to late spring.