1. Term Project: Correlation of AO Indices vs. Corresponding Tornadic Centroid Location and Total Tornado Count April Haneklau EAS 4480 – Environmental Data Analysis April 23, 2013

2. Introduction Idea: Positive AO = Tornadic Activity Reason: Warmer temperatures  Sharper temperature gradients Cold air Warm air

3. Overview Analyzing correlation between AO indices and tornadic activity of April of each year. Monthly = 1990-2012. Daily = 2000-2012 Data collected from NCDC Storm Events Database and CPC Teleconnection Archives. April 2011!

4. Primary Calculations Weighted Average: From daily storm reports, a weighted average (by EF/F rating) latitude and longitude value was calculated for each year's April. Purpose: to show location of centroid of tornadic activity Correlation Coefficient & Least-Squares Regression Calculated the correlation and least- squares regression between AO and monthly weighted latitudes & longitudes, monthly tornado count and daily tornado count. Covariance & CPSD Calculated cross power spectral density to identify possible shared cycles observed in periodogram. Calculated lag time from covariance of daily data to identify lag between observed AO & tornadic activity. Periodogram Calculated and plotted periodogram of monthly weighted latitudes & longitudes, monthly tornado count, daily tornado count, monthly AO indices and daily AO indices. Purpose: to identify possible cycles.

5. Weighted Average Calculation April 2011!

6. Histogram: Positive vs. Negative AO

7. Correlation Coefficient & Lag Monthly VariablesDaily Variables R 2 Valuep value Tornado Count 0.56470.005 Weighted Latitude 0.00390.9860 Weighted Longitude 0.000980.9965 Significant! R 2 Valuep value Tornado Count (total) 0.04660.3597 Tornado Count (tornadic days) 0.08180.2047 Lag time-29 days(?)

8. Least-Squares Regression East West North South April 2011!

9. Periodogram

10. CPSD Estimate

11. Houston, we have a problem... Tornado rating scale changed from F to EF in 2007. Thus, weights could potentially be slightly skewed. Data not well obtained/archived before 2000; 107 days in 1990's had incomplete data and were excluded from calculations. Only analyzed 23 years; likely would see significant or real peaks with larger dataset.