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SOMs Work

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

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  1. SOMs Work Analysis Region Top Widespread Events Location of Extreme Precipitation

  2. 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

  3. 99th Percentile

  4. Top 10 DJF Composite

  5. Top 5 DJF Composite

  6. Top DJF Event

  7. 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

  8. Native WRF output vs. NCDC-based WRF output

  9. 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

  10. Native WRF: L-H-L signal seems to be the dominant circulation feature. Highly accessed nodes on the periphery of SOM space, in general.

  11. 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.

  12. 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.

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