Impact of Eastern and Central Pacific ENSO events over the Continental United States

This study compares the effects of the extreme warm and cold phase of various ENSO indices over the continental United States by compositing multiple precipitation datasets. Recently developed ENSO indices (Kao and Yu, 2009) separate different ENSO modes into those more regionally represented by SST anomalies over the Eastern-Pacific (EPAC) and Central Pacific (CPAC). Composites of monthly precipitation fields around EPAC and CPAC are based on: the Global Precipitation Climatology Project (GPCP), University of Delaware Global precipitation dataset, NASA Land Data Assimilation Systems (NLDAS) precipitation data, and the Parameter-elevation Regressions on Independent Slopes Model (PRISM) precipitation dataset. Results show that extreme phases of EPAC and CPAC ENSO indices affect various parts of the continental United States with significant differences, which appear more accentuated over the Mid-West US. Such spatial patterns also show different behavior on seasonal impacts. Some plausible explanations on the different behavior of precipitation anomalies appear to be associated with modulation of storm tracks and their intensity. We also highlight regional and sub-regional differences of the composited pattern among the various precipitation datasets.