Authors: Scott Sheridan*, Kent State University, E Tyler Smith, Kent State University, Cameron C Lee, Kent State University, Omon Obarein, Kent State University
Topics: Climatology and Meteorology
Keywords: seasons; summer; climate change; synoptic climatology
Session Type: Paper
Presentation File: No File Uploaded
When deconstructing the manifestations of climate change, one key component that is relatively understudied is seasonal length. As part of recent work on climate change over North America, we have explored changing seasonality using several different synoptic methods. Using self-organizing maps, we have clustered several different variables, including 500-mb geopotential height and sea-level pressure, in multiple domains across the continent. Across the entire domain, the predominant trends over the last 40 years are increasing frequencies of warm ridge-like patterns during the summer. In regions across the eastern and central US, these summer-like patterns are also extending into autumn with greater frequency as well. This pattern is echoed in trends in surface weather types based on the Spatial Synoptic Classification (SSC) and Gridded Weather Typing Classification (GWTC). With the SSC, the tropical weather types have gained in frequency at over 1 day per decade across many stations in the month of September alone. The final five years of the data set, 2015-2019, show consistent anomalies extending well into autumn through much of the Midwestern, eastern, and southern US, with Dry Tropical occurring nearly four times as much as is expected climatologically during September and the first week of October at a number of stations, and anomalies of up to 6 additional days of Moist Tropical at several stations in the southeastern US. With the GWTC, since 1979, Humid Warm air masses in New England and Humid air masses in the central US are occurring 1.0 to 1.7 days/decade in September.
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