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SOMs Work. Analysis Region Top Widespread Events Location of Extreme Precipitation. DJF Master SOM. Produced with ERA-Interim + SN WRF-50.hPa MSLP anomalies (1989-2007) Widespread extreme days (99 th percentile, w/ at least 25 grid points) from WRF mapped onto Master SOM. 99 th Percentile.
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SOMs Work Analysis Region Top Widespread Events Location of Extreme Precipitation
DJF Master SOM • Produced with ERA-Interim + SN WRF-50.hPa MSLP anomalies (1989-2007) • Widespread extreme days (99th percentile, w/ at least 25 grid points) from WRF mapped onto Master SOM
Extreme Node Selection • In some analysis regions, nodes are being accessed that don’t show favorable circulation for widespread precip. extremes • Some regions may need a smaller Master SOM, as strong features far from region may confound node selection
Comparing Node Frequencies • Extracted WRF widespread extreme events from N. American analysis region • Extracted NCDC station extremes from same regions • Extracted WRF output from grid points closest to NCDC station • Compared node frequencies from the three sources
Native WRF: L-H-L signal seems to be the dominant circulation feature. Highly accessed nodes on the periphery of SOM space, in general.
NCDC observations don't really show the L-H-L pattern that we find in the model output; we find a strong Aleutian low and a region of relaxed high pressure over the eastern part of domain.
Similar L-H-L as found in native WRF. Highest frequency node, however, shows a low pressure feature over Gulf of Alaska, with H pressure over the Bering Strait.