Climatological Analysis of ENSO and AO Impacts on Temperature and Precipitation across the U.S. Corn Belt 1980-2010

Teleconnections and their associated impacts on climatologically normal weather conditions have been studied for several decades with a deeper understanding of their impacts to climate variability found in more recent years. Examples of past teleconnection impact analyses include increase or decrease in flooding events, increase or decrease in extreme weather events such as hurricanes and tornadoes, and impacts on crop yield. This climatology is developed to mainly service the agricultural community but has applications to general weather forecast guidance as well. This El Niño Southern Oscillation (ENSO) and Arctic Oscillation (AO) climatological analysis is part of the Useful to Usable Project (USDA and NIFA) that covers the North Central Region and seeks to transform climate variability and change information for cereal crop producers into an easy to understand (and use) set of decision support tools to make more informed decisions, improving the resilience and profitability of farms amid variable climate changes. This climatology is unique in that it uses observed weather /climate and teleconnection data to develop a series of guidance tools to help producers make more informed decisions for planting, irrigation, and harvest. The ENSO and AO climatology tool is inclusive of observed mean temperature, observed precipitation, and extreme temperature and precipitation data (number of days per month Tmax ≥ 90 °F, Tmax ≤ 32 °F Tmin ≤ 32°F, precipitation ≥ 0.1 inch, and precipitation ≥1.0 inch) at a spatial resolution of crop reporting district/state climate division level from 1980-2010.

The developed teleconnection climatologies for observed mean temperature and observed precipitation are analyzed as departures from climate division normal and findings are presented with maps, bar graphs, and look-up tables to show wetter than normal and drier than normal regions by month during a given teleconnection phase. The difference of observed mean temperatures and observed precipitation between teleconnection phases is tested with ANOVA analysis to determine statistical significance. The AO has influence with statistical significance on mean temperatures during the months of March through December. ENSO has a strong influence on mean temperatures for the months July, August, September, October, and December. When reviewing statistical significance of the variation in precipitation, ENSO has a greater impact on precipitation. The AO has marked regions of precipitation during the months of January, March, April, and October. ENSO has marked regions of precipitation variation during the months of February, March, May, June, August, and September. Analysis of climatology and crop yield is also completed for the 1980-2010 time period. Results show that the average AO phase across three time frames during the growing season (May-July, July-Sept., and May-Sept.) has a higher correlation to crop yields than ENSO suggesting that crop yield is more greatly impacted by short term weather patterns (e.g. 2 weeks) than seasonal weather conditions. Findings of extreme temperature and precipitation data will be presented as well.