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Objectives

Climatic Influences on Summer Drought in Alabama Jason C. Senkbeil (jcsenkbeil@bama.ua.edu) Department of Geography. Identify extreme drought years Palmer Drought Severity Index (PDSI) Recurrence intervals Climatic Influences Growing Season Drought Monthly Drought. Influences on Drought

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Objectives

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  1. Climatic Influences on Summer Drought in AlabamaJason C. Senkbeil(jcsenkbeil@bama.ua.edu)Department of Geography

  2. Identify extreme drought years Palmer Drought Severity Index (PDSI) Recurrence intervals Climatic Influences Growing Season Drought Monthly Drought Influences on Drought Teleconnections SST Variables El Nino/La Nina Nino 1.2 Nino 3.4 Pacific Decadal Oscillation (PDO) Atlantic Multidecadal Oscillation (AMO) Pressure Variable North Atlantic Oscillation (NAO) Objectives

  3. State Averaged March – October PDSI Approximate Recurrence Interval Instrumental PDSI

  4. Reconstructed Annual PDSI 10 Most Severe Growing Season Drought Years (Instrumental)

  5. Spatial Comparisons of Extreme Drought Years

  6. Correlations with State Averaged Growing Season PDSI and Teleconnections All Years • Atlantic teleconnections have stronger relationships with Alabama PDSI for the entire duration of the growing season for all years • These are weak relationships • AMO, r = -0.27 (p .04*) • NAO, r = 0.21 (p = 0.11)

  7. What is the AMO

  8. The North Atlantic Oscillation Negative Phase (left) Positive Phase (below)

  9. Positive PDO (left) Negative PDO (right) 1995 – 2007 +PDO, +AMO 2008 PDO shifted cooler

  10. Correlations Between PDSI and Teleconnection Values During Strong Drought Years

  11. La Nina Winters vs Summers WINTERS SUMMERS

  12. NO SMOKING GUN FOR ALABAMA GROWING SEASON DROUGHT AMO AMO and PDO phase relationship Nino 1.2 Nino 3.4 NAO (nearly significant) Commonalities During Extreme Drought Years (PDSI < - 2.8, N = 4) Very Cold Nino 1.2 Region August - October Cold/Cool Nino 3.4 Region Negative PDO Positive AMO GROWING SEASON RESULTS SUMMARY

  13. Extreme Drought Months

  14. Extreme Drought Month Commonalities Warm AMO when PDSI is ~-3, Neutral AMO when PDSI is < - 4 Cold Nino 3.4 Cold Nino1.2 Ranked Factors Contributing to Drought AMO Complex Relationship Cold Nino 1.2 Late summer /early fall Cold Nino 3.4 NAO Negative trends toward drought PDO Negative trends toward drought Conclusions

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