SOMs Work Analysis Region Top Widespread Events Location of Extreme Precipitation.
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SOMs Work Analysis Region Top Widespread Events Location of Extreme Precipitation
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99 th Percentile
Transcript of SOMs Work Analysis Region Top Widespread Events Location of Extreme Precipitation.
SOMs Work
Analysis Region Top Widespread EventsLocation 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
99th Percentile
Top 10 DJF Composite
Top 5 DJF Composite
Top DJF Event
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
Native WRF output vs. NCDC-based WRF output
Comparing Node Frequencies
1. Extracted WRF widespread extreme events from N. American analysis region
2. Extracted NCDC station extremes from same regions
3. Extracted WRF output from grid points closest to NCDC station
4. 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.
