Rain gauge derived precipitation variability over Virginia and its relation with the El Nino southern oscillation

Abstract

The El-Nino/Southern Oscillation (ENSO) Phenomenon has a strong impact on local and regional scale climate through strong teleconnections affecting the coupled ocean-atmosphere and even land system. Recent studies have pursued the effects of such periodic events on different climatological and meteorological parameters. This study focuses on ENSO impact on local precipitation patterns. We study the precipitation patterns derived from gauge stations over Virginia, USA. Forty years of the Hourly Precipitation gauge Data (HPD) jointly developed by the National Climatic Data Center (NCDC) and the Forecast Systems Laboratory (FSL) at five gauge locations in Virginia are considered. High frequency random noise at each station is removed through wavelet decomposition. A Morlet wavelet basis function is then fitted to the non-seasonal data to derive the interannual and longer periodic signals. Three to five years' cycles are observed in the anomaly signal in keeping with the 2–8-year period of ENSO signals reported in the literature. An Empirical Mode Decomposition (EMD) is also applied to the data set. The signal is found to correlate reasonably well with the Southern Oscillation Index (SOI) with a correlation coefficient of 0.68 at a confidence level of 95% for the stations. Cross-spectral coherency and phase analysis reveals a strong physical link between precipitation and ENSO. One of the major outcomes of this study is that ENSO may strongly affect local precipitation.