Spatial Characterization of Storm Internal Precipitation

Distribution for the Southeastern United States

(1980-2009)

David M. BrommerDepartment of Geography

University of Alabama

Introduction Quantifying the character of

precipitation• Precipitation amount• Precipitation timing• Precipitation intensity• Precipitation modeling

Why?• Capture the variability in precipitation to

plan, design, and manage water resources

Data and Methods Hourly Precipitation Dataset 3240

• National Climatic Data Center 6,500 primary, secondary and cooperative

weather stations from 1900 to present Reduced to 143 stations

• Primary (first-order) stations • Precipitation measured to 0.254 mm hr-1 (0.01 inch)• No data gaps from 1980 – 2009

Precipitation events last at least three hours (no events of one- or two-hour duration included)

Data and Methods Why three-hour or longer events?

• Statistical tests required a minimum of three data points

• Air mass (pulse)-type thunderstorms removed• Assess the variability within longer-duration

precipitation occurrences 149,197 individual, three-hour or longer

events identified To assess internal variability, skewness

and kurtosis are used

* Precipitation events three hours or longer

Precipitation Skewness

Precipitation Kurtosis

Average number of maxima (peaks) within the precipitation disribution

Conclusion Internal character of precipitation

across the U.S. highly variable • Especially the Southeast• Seasonal variability, too

Convective events, initially, play a roll in determining internal distribution

Future work?• Seasonal signal (cold-season, in paticular)• Incorporate additional stations

15-minute data?