ENSO TELECONNECTIONS WITH PRECIPITATION, MOISTURE REGIME AND WATER AVAILABILITY IN THE OHIO RIVER WATERSHED

Over the past twenty years, numerous studies have improved our understanding of the relationship between the El Niño Southern Oscillation (ENSO) phenomenon and the global climate system. Some of these studies have detected remote associations (teleconnections) between ENSO and global precipitation, and regional effects have been described for the western United States. Most of these studies, however, are framed within global or continental scales, and no attempts have been made to scale down these teleconnections and study its impacts at the watershed scale. Here we present the results of analysis from over 200 weather stations in Ohio, with data spanning from 1970 to 2006. We used precipitation data to identify the teleconnections between ENSO and precipitation in four sub-watersheds draining to the Ohio River. The same data was used to establish linkages between ENSO and extreme weather events, such as floods and droughts, in those basins. Annual and monthly precipitation patterns were modeled using kriging interpolation. Regression analysis was used to evaluate the correlation between precipitation patterns and the multivariate ENSO index (MEI). Negative values of the MEI represent the cold ENSO phase (La Niña), while positive MEI values represent the warm ENSO phase (El Niño). Our results indicate strong moisture gradients during La Niña years, with increased precipitation along the Ohio River basin and extreme drought limited to the northwestern part of the State. During El Niño years, drought conditions, although mild, are more widespread, reaching all the way to the Ohio River Valley in the south. The most severe drought conditions were observed during the El Niño years of 1987 and 1991. Flooding conditions were mostly confined to the Ohio River valley, and the most intense were observed in the La Niña years of 1975 and 1989.