Analyzing the Frequency of High Amplitude Wave Patterns and Their Relationship with Extreme Weather Events in the United States

Recent studies suggest that Arctic Amplification (AA) due to climate change has reduced the temperature gradient in the Northern Hemisphere, resulting in zonal wind reduction and an increase in wave amplitudes in the midlatitudes. We explore the hypothesis that this change in the atmospheric circulation is leading to more extreme weather events in the United States. To analyze these events, we gather the 500mb data from the National Centers for Environmental Prediction–National Center for Atmospheric Research reanalysis (NCEP/NCAR Reanalysis 1) and then put this data into a Self- Organizing Map (SOM). By utilizing a SOM, the data can be organized into similar circulation patterns, showing which patterns are occurring more frequently. Events where certain weather patterns are stagnant can be located and correlated with weather patterns that lead to heavy precipitation and drought events. Specific patterns can also be isolated to find the waviness of each weather pattern. We will do this by calculating the length of the 500mb geopotential height contours from the reanalysis data for each pattern identified by the SOM, as well as the sinuosity for each time step in the data. Atmospheric circulations with longer lengths will be used to locate persistent ridge patterns. Once identified, these stagnant weather patterns are analyzed and correlated with extreme weather events in the United States.