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<br />periods of stonns were considered separately. The total rain volume was also well correlated with the
<br />maximum single-,scan rain volume. These findings suggest the possibility of estimating total stonn rain
<br />volume at its maximum stage of development.
<br />
<br />It is hoped that improvements in rainfall estimation over areas using satellite data may result from
<br />further studies, since the precipitating part of a cloud picture can be more accurately defined for the
<br />growing period of a cloud's history.
<br />
<br />Doneaud, A. A., S. Ionescu-Niscov, D. L. Priegnitz, and P. L. Smith, 1984: The area-time integral as an
<br />indicator for convective rain volumes. Journal of Climate and Applied Meteorology, 23:555-561.
<br />
<br />Digital radar data are used to investigate further a simlPle technique for estimating rainfall amounts on
<br />the basis of area coverage infonnation. The basis of the technique is the existence of a strong
<br />correlation between a measure of the rain area coverage and duration called the area-time integral (A TI)
<br />and the rain volume. This strong correlation is again demonstrated using echo cluster data from the
<br />North Dakota Cloud Modification Project 5-cm radars.
<br />
<br />Integration on a scan-by-scan basis proved to be superior for detennining A TI values to the hour-by-
<br />hour integration Illsed previously. A 25 dB(z) reflectivity threshold was found suitable for the A TI
<br />calculation. The correlation coefficient on log-log plolts of cluster rain volume versus A TI is
<br />approximately 0.98, indicating a power-law relationship between the variables. The exponent of that
<br />relationship is just a little higher than one, which indicates that the cluster average rainfall rate is almost
<br />independent of the stonn size and duration.
<br />
<br />A test of the relationship derived from one set of data (1980) against an independent set (1981) showed
<br />it to be consistent. Using the 1980 relationship to estimate the 1981 cluster rain volume for a given
<br />A TI, the uncertainty of the rain volume estimates was found to be -31 %, +46%.
<br />
<br />Doneaud, A. A., S. Ionescu-Niscov, and J. R. Miller, Jr., 1983: The evolution of the average rain rate during
<br />stonns in a semi-arid climate. Preprints, 21st Conferelflce on Radar Meteorology, Edmonton, Alberta,
<br />Canada, September 19-23, 1983. American Meteorological Society, Boston, MA, 15-20.
<br />
<br />No abstract.
<br />
<br />Doneaud, A. A., S. Ionescu-Niscov, D. L. Priegnitz, and P. L. Smith, 1983: The area-time integral as an
<br />indicator for convective rain volumes. Preprints, 21st Conference on Radar Meteorology, Edmonton,
<br />Alberta, Canada, September 19-23, 1983. American Meteorological Society, Boston, MA, 675-680.
<br />
<br />No abstract.
<br />
<br />Durgunoglu, A., H. V. Knapp, and S. A. Changnon, 1988: PACE watershed model (PWM): Vol. 2,
<br />Weather Modification Simulations. SWS Contract Report 439 to NOAA. Illinois State Water Survey,
<br />Champaign, IL, 55 pp.
<br />
<br />No abstract.
<br />
<br />I'
<br />,
<br />
<br />Elliott, R. D., and D. A. Griffith, 1984: Final report on modeling and radar/rawinsonde analysis for
<br />North Dakota. NAWC Report SLWM-84-1. North American Weather Consultants, Salt Lake City, UT,
<br />73 pp.
<br />
<br />No abstract.
<br />
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