1 / 19

A review of 2005-06 Extreme Events

A review of 2005-06 Extreme Events. Klaus Weickmann, ESRL/PSD. Background and variables used Extreme sea surface temperatures Focus on 850 mb temperature anomalies also Dartmouth Flood Monitor 1968-2006 and Oct 2005-Sept 2006 > 2 sigma anoms; < -2 sigma anoms

zada
Download Presentation

A review of 2005-06 Extreme Events

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. A review of 2005-06 Extreme Events Klaus Weickmann, ESRL/PSD • Background and variables used • Extreme sea surface temperatures • Focus on 850 mb temperature anomalies • also Dartmouth Flood Monitor • 1968-2006 and Oct 2005-Sept 2006 • > 2 sigma anoms; < -2 sigma anoms • Northern Hemisphere time series of % area • Global map of % days with extreme temps • Extreme cases (1998, 2002, 2003, 2005, 2006) • Speculation on Synoptics • USA monthly temp and precip xtremes Special thanks to: Cathy Smith, Don Hooper, Klaus Wolter, Alex McColl, Barry McInnes

  2. May-Sep 1998, 2002, 2003, 2005, 2006 composites on right SSTA H H L L L H H 200uv OLRA

  3. Temperature 850 hPa Annual mean standard deviation 1968-2006 Annual mean 1968-2006 Note: full seasonal cycle of standard deviation used in analysis that follows

  4. ‘98 850 temperature Oct ’68 – Sep ’06 91-day running mean ‘06 ‘03 ‘05 < -2 σ ‘02 > +2 σ % area 20-90N ~Jan ‘77 Pinatubo ‘82-83 Mean 2.46% 2.06%

  5. Oct 1968 to Sep 2006 % days > +2 σ Shading: 2-4%, 4-6%, >6% % days < -2 σ orography not “blocked out”

  6. 11 Sep 850 temperature Oct ’05 – Sep ’06 daily plus 91-day running mean 15-16 Aug < -2 σ > +2 σ 21 Jul 8.7% % area 20-90N 11 Jul 2%

  7. 3.5C! Oct 1968 to Sep 2006 850 mb temperature anomalies (degrees C) Shading: 0.5-1.0, 1.0-2.0, 2.0-3.0 850 mb temperature normalized anomalies Shading: 0.5-1.0, 1.0-1.5

  8. Oct 2005 to Sep 2006 % days > +2 σ Shading: 5-10%, 10-15%, >15% % days < -2 σ orography not “blocked out”

  9. ‘98 850 temperature Oct ’68 – Sep ’06 91-day running mean ‘06 ‘03 ‘05 < -2 σ ‘02 > +2 σ % area 20-90N ~Jan ‘77 Pinatubo ‘82-83 Mean 2.46% 2.06%

  10. Percent of days out of 91 with 850 hPa normalized temperature anomalies greater than +2 sigma Shading levels 8-16%, 16-32%, 32-48%, >48% Jun 13 – Sep 11, 1998 May 20 – Aug 18, 2002 Jul 14 – Oct 3, 2005 Aug 3 – Nov 3, 2003 Jul 12 – Oct 10, 2006

  11. Daily dates with maxima in % area > +2 sigma during Jul 12 – Oct 10 2006 USA west coast heat wave

  12. Speculation on Synoptics Two areas of tropical forcing due to extreme SSTs in warm pool region MJO-like behavior: faster time scale and consolidation of anomalies, esp. summer/fall? Leads to more transient “split flows” with stronger westerly winds in tropics & subtropics Favors extreme ridging events and subtropical jets spiraling into mid-latitudes Reflecting increased heat transport due warm tropical SSTs?

  13. Summary and Conclusions • Expanded > 29C SSTs in warm pool region, especially since July 2001 • 2005-06 continues recent string of extreme temperatures during summer/fall, and more general trend of increasing warm extremes • > 2 sigma more often, over larger area and especially at warm time of year • Synoptic discussion of Nov-Dec 2005 (USA west coast precip), April 2006 (CA precip) and June 2006 (USA east coast precip) extreme events @ http://www.cdc.noaa.gov/MJO/Forecasts/climate_discussions.html

  14. Possible impact of assimilation model errors on results?

More Related