The Sinuosity of Midlatitude Atmospheric Flow and Its Potential Impacts on Extreme Weather Events in the Northern Hemisphere

We explore the hypothesis that Arctic Amplification (AA) due to global climate change is decreasing the zonal winds, creating a more meridional flow in the mid-latitudes, and causing more extreme weather events. A threshold for extreme high amplitude wave patterns and their stagnancy can be determined creating a climatology using a Self Organizing Map (SOM). This allows for an analysis of how these events may correlate to high impact weather events such as flooding, cold air outbreaks, heat waves, and droughts.

We use the NCEP/NCAR reanalysis Northern Hemisphere 500mb geopotential heights from 1948-present to create a climatology of weather patterns using a Self Organizing Map method. By utilizing a SOM, we can determine the frequency of each weather pattern through time and flag events where the same weather pattern is repeated over and over and is therefore stagnant. We can also find the length of the 500mb geopotential height contours from the reanalysis data and calculate the sinuosity (length) for each time step that was used to create our SOM. By knowing which days fall into which SOM pattern, we discover the sinuosity of each weather pattern at each location and then determine statistical thresholds to define large amplitude wave patterns that are stagnant. We then explore the precipitation results and impacts from events found within each high amplitude pattern.