Extended Abstract (640K)JP2.12
Cloud-to-ground lightning and surface rainfall during the Great Flood of 1993
Nicole M. Kempf, Univ. of Arizona, Tucson, AZ and NOAA/NWS, Tulsa, OK; and E. P. Krider
Relationships between cloud-to-ground (CG) lightning, as reported by the U. S. National Lightning Detection Network™ (NLDN), and surface rainfall, as reported by NWS Cooperative Observers, have been examined during the Great Flood of 1993. The daily precipitation volume per reported CG flash (CGF) over the Greater Upper Mississippi River Basin (GUMRB) ranged from 4.0 x 104 to 4.3 x 106 m3/CGF with a mean and median of 4.6 x 105 and 1.9 x 105 m3/CGF, respectively, during June, July, and August, 1993. The monthly rain volume per reported CG flash ranged from 6.3 x 104 to 2.1 x 105 m3/CGF with an overall mean of 1.8 x 105 m3/CGF. Similar ratios were found for the Upper Mississippi River Basin (UMRB) that is imbedded within the GUMRB. For the entire summer season, there were about 6.5 x 1011 cubic meters of rainfall over the GUMRB and there were 3.6 x 106 CGF reported by the NLDN, which gives an overall seasonal mean of 1.8 x 105 m3/CGF. If we correct the lightning counts for an imperfect NLDN detection efficiency, we estimate that there were actually about 5.4 x 106 CG flashes over the GUMRB, and therefore, the actual seasonal mean rain volume was about 1.3 x 105 m3 per CGF. The above values are remarkably similar to the summer mean of 1.1 x 105 m3/CGF obtained by Petersen and Rutledge (1998) over the mid-continental U.S. and are consistent with other studies on daily and storm scales. The above ratios are larger than, but still consistent with, an estimate of the excess stream volume per excess (reported) CG flash from the UMRB, 6.8 x 104 m3/CGF, based on streamflow measurements at Keokuk, IA.
Joint Poster Session 2, Instrumentation and Remote Sensing (Joint with the Symposium on Observing and Understanding the Variability of Water in Weather and Climate and the 17th Conference on Hydrology)
Tuesday, 11 February 2003, 9:45 AM-9:45 AM
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