Teleconnections and height patterns: comparing recent winters

1. Teleconnections and height patterns:comparing recent winters Richard H. Grumm and Robert Hart V_3.0 17 March 2004 27 Feb 2003 26March 2002

2. Snow in Israel-Snow in DCLate Feb 2003 is there a connection Jerusalem Road to Damascus

3. Introduction • What are teleconnections? • Brief History of teleconnections • Using Teleconnections • long-term forecast aspects • short-term forecast aspects • Flow regimes • Good old fashion teleconnections • New concepts and applications • nodes and antinodes • A 2003-2004 perspective

4. Teleconnectons defined Wallace and Gutzler MWR 1981 • Definition:significant simultaneous correlations between temporal fluctuations in meteorological parameters at widely separated points on the earth. • Provide evidence of transitory behavior of planetary waves • show evidence of fluctuations with times scales on order of weeks. • Suggest preferred region of standing wave nodes and antinodes. (nodes-similar sign)

5. Similar definition O’Connor 1969 • Definition:the favored modes for coupling large-scale abnormalities of the atmospheric circulation as determined statistically or empirically. • Rossby’s centers of action (1939) concept proved teleconnections had a physical basis. (nodes) • Found great use to improve forecasts based on patterns and centers of action (nodes) • developed teleconnection maps correlating an anomalous trough/ridge at a 10x10 Lat/Lon region to other anomalies and anti-anomalies around the hemisphere. (nodes and antinodes)

6. The well known El Nino Teleconnectionthe temporal fluctuation about globe associated with El Nino

7. How El Nino Teleconnects Walker Circulation impacts

8. Teleconnectons Wallace and Gutzler MWR 1981 • Implications: • A standing wave in one location favors the existence of a wave downstream at a known location. Therefore, • there exist, preferred trough/ridge locations • may be referred to as nodes and antinodes • Their existence allows the use of indices to quantify or measure flow patterns associated with these features. • The NAO correlates the flow over the Atlantic Basin • The ENSO sign has its own teleconnections in the both northern and southern hemispheres • other known indices (EP,AO etc, etc…)

9. Teleconnectons Wallace and Gutzler MWR 1981 • Things to consider: • wave patterns and flow can be measured and teleconnected. • ocean indices can be measured and teleconnected • the indices are teleconnected, typically by regression, to a favored mode of weather conditions at a location. • Not all correlations are one-to-one • negative correlations too, ANTINODES • These correlation’s have direct forecast applications, especially on the scale of weeks and months.

10. Teleconnecton’s A History Perspective • Southern Oscillation (SO), identified and documented in 1897. • Connecting weather and long term wet/dry periods in India and Australia. • Walker and Bliss (1932) improve SO documentation. • Association of weather patterns in western Europe to eastern United States • trough in western Europe correlates well with trough in eastern North America. NODES • A ridge in western Europe ~ ridge in eastern North America

11. Known North Hemisphere Teleconnection Patterns • North Atlantic Oscillation (NAO) • Negative phase: cold eastern NOAM/Europe • Positive phase: warm wet Europe / eastern NOAM • We shall show how eastern US nodes/antinodes fit into the NAO and PNA pattern nicely. • North Pacific Oscillation (NPO) • Pacific North American Pattern (PNA) • PNA > 0 similar to NAO <0 • The zonally symmetric seesaw/ Quasi-Biennial Oscillation (QBO)

12. Cutting to the Chaseanomaly correlation showing nodes and antinodes Correlation point

13. Winter 2003-2004

14. North Atlantic Oscillation (NAO) • Statistical correlation’s: • negative correlation severity of winters in Greenland and Labrador and northwestern Europe. • Negative correlation between MSLP at Iceland and the eastern Atlantic • Winter temperatures were used to determine severity • Deep Icelandic Low: Positive NAO • cold advection over Labrador and Greenland • warm southwesterly flow into Europe and southern flow into eastern North America.

15. Pacific North American Pattern (PNA) • There are clearly 2 preferred flow patterns over North America • relate upper air pattern mid-Pacific to eastern North America with two preferred modes: • Positive Mode • Ridge along west coast with negative nodes • southeastern US (35N/75W) • near 45 N in the mid-Pacific (40N/150W) • so called Postive PNA • Negative Mode • more zonal flow across north America • lack of Pacific Ridge, can flood US with Pacific air.

16. PNA > 0 Positve Yellow Negative Blue Nodes/Antinode antinode Nodes

17. Teleconnection Mapsrelate flow pattern • Initial teleconnection’s used operationally • maps of anomalies in 10x10 Lat/Lon bands • relate a known height anomaly (Lat/Lon) with other associated anomalies • For example • Compute height anomaly at 30 N and and 40W • see what the mean anomalies are around the hemisphere when this anomaly exists • often find centers of action • correlation centers • low off eastern US correlates well with ridge over northern Atlantic • negative nodes typically have downstream preferred location of next negative node

18. Teleconnection Map Example(O’Connor)30N/40W Negative in Winter

19. Teleconnection Map Example(O’Connor)30N/50W Negative in Winter

20. Teleconnection Map Example(O’Connor)30N/60W Negative in Winter

21. Trof Trof Ridge Teleconnection Map Example40N70W: Winter Positive (~PA)

22. Nodes and Antinode • Centers of action from re-analysis data • Use eastern US to compare to previous 40/75W box • Examine impacts on past three winters • Note how our PA node correlates well with the preferred nodes of the PNA and NAO. • A forecast tool?

23. AntiNode European Node PA Node Pacific Node Autocorrelation JA-FE-MA 01correlation point 40N/75W

24. Winter 01 Explanationnodes-antinodes show why PNA evolved • Correlation point is 40W/75W • see white dot correlation to self is 1 • high correlation about point hot colors • Positive Nodes: • coast of Europe (~0.6) • Gulf of Alaska/mid Pacific (~0.6) • Negative Nodes (antinodes) • western North America (~-0.6) (South of 2001) position • southern Atlantic (~0.6) west of 2001

25. Jan-Mar 2001 Jan-Mar 2000 Centers of action for 40/75 some year-year variability

26. Cold US Decembers1989 and 2000

27. DEC 1989Anomaly and Standardized anomalyNodes and mean 500 hPa heightsCOLD

28. DEC 2000Anomaly and Standardized anomalyNodes and mean 500 hPa heightsWARM

29. DEC 2001Anomaly and Standardized anomalyNodes and mean 500 hPa heightsWARM

30. Jan 2002Anomaly and Standardized anomalyNodes and mean 500 hPa heightsWARMnote +NAO Pattern

31. Feb2002Anomaly and Standardized anomalyNodes and mean 500 hPa heightsWARM

32. 2003 Summer • Wet eastern US • Warm and dry western Europe • Record warmth Italy Jun • Record warm UK-FR-GDR August

33. NOAM and Europe Flow

34. Autumn 2003 • Correlation and nodes expand southward • More notes of value • Good Eastern US and western Europe correlation centers

35. Autumn Patterns

36. Winter 2003-2004 • Big node over eastern US • Some correlation to western Europe

37. Winter Patterns 2003-2004

38. NOAM Winter 2003 verse 2004

39. Conclusions • Teleconnections ~ weather to flow • Rossby waves dictate location of troughs/ridges • specific mean wavelengths imply existence of preferred nodes and antinodes • these preferred locations led to some of the well-known indices (PNA) • Can produce these for any Lat/lon box on globe • relate weather to anomalies of heights- • mean trough~cold or mean ridge~warm • forecast tools on the order of weeks

40. Conclusion-Indicesnow your a “node-it-all” • NAO: • North-South Dipole • teleconnect’s well with weather in Europe, Greenland and western North America • PNA • quadrapole (nodes and antinodes) • teleconnects well with NOAM weather • Trough in eastern US correlates with trough in Europe-relates PNA to NAO

41. References • Namias, J., 1978: Multiple Causes of the North American Abnormal Winter 1976-77. Mon. Wea. Rev., 106, 279-295. • O’Connor, J.F. 1969: Hemispheric Teleconnections of Mean Circulation anomalies at 700 millibars. ESSA Technical report WB10, US Dept.Commerce. • van Loon, H., and J. C. Rogers, 1978: The seesaw in winter temperatures between Greenland and northern Europe. Part I: General description. Mon. Wea. Rev., 106, 296-310. • Wallace, J., and D. Gutzler, 1981: Teleconnections in the Geopotential Height Field during the Northern Hemisphere Winter. Mon. Wea. Rev., 109, 784-811. • Burroughs, W.J, 2002: Climate Change. Cambridge Univ. Press, 1-298.

42. Computing the PNAknow the sign of the anomaly at center of action • Base on Anomalies (nodes and antinodes) • 4 Locations • SMidPac (SMP) = 20N/160W • NMidPac (NMP) = 45N/165W • WNOAM (NNM) = 55/115W • SERNUS (SUS) = 30N/85 • PNA= (SMP - NMP + NNM - SERNUS)/4 PNA > 0 : Strong Ridge along western Canada PNA < 0 : Trough or zonal flow along western Canada

43. The zonally symmetric seesaw • Lorenz (1951) first identified this seesaw effect in the MSLP fields • A similar patten has been associated with the Quasi-biennial oscillation (QBO) • pressure changes associated with sudden warming’s (mainly in polar regions) • effect most notable in Stratosphere (20-30 km) • QBO has been related to surface pressure changes too and may have long term forecast skill on monthly/seasonal level. • NH winters may related to phase of QBO at 50 hPa in the tropics

44. Quasi-Biennial Oscillation(QBO) • 20-30km in Stratosphere • Measured near 30 hPa • Wind reversal over equatorial regions every ~27 months • Easterly to westerly • Teleconnects to weather patterns • Correlated to some temperature records • And behavior of ENSO, • Hurricane activity in the Atlantic • Related to upward propagating easterly Kelvin waves and westerly Rossby waves.