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Rainfall results, 1970-1975: Florida area cumulus experiment
Science (New York, N.Y.)
|February 25, 1977
Summary
Dynamic seeding in the Florida Area Cumulus Experiment (FACE) showed no effect on rainfall initially. However, further analysis revealed seeding increased rainfall in moving echo clouds and target areas.
Area of Science:
- Cloud physics
- Atmospheric science
- Weather modification
Background:
- The Florida Area Cumulus Experiment (FACE) investigated dynamic seeding effects on rainfall.
- Early analyses of 48 experimental days in 1975 showed no significant rainfall alteration.
Purpose of the Study:
- To re-evaluate FACE data using advanced statistical methods.
- To determine if dynamic seeding impacts rainfall under different convective echo conditions.
Main Methods:
- Stratification of experimental days based on convective echo motion (moving vs. stationary).
- Stepwise regression analysis incorporating echo motion covariate and natural rainfall predictors.
- Comparison of rainfall in fixed target areas and floating target clouds.
Main Results:
- Initial analysis of 48 days yielded no evidence of seeding altering rainfall in the fixed target area.
- Stratification by echo motion provided significant insights.
- Seeding showed a positive, statistically significant effect on rainfall in moving echo categories (subject clouds and overall target area).
- Tentative evidence suggests seeding increased rainfall in floating targets for stationary echoes, with no net change in the overall target area.
Conclusions:
- Echo motion is a critical covariate for assessing dynamic seeding effectiveness.
- Dynamic seeding may enhance rainfall, particularly in specific meteorological conditions.
- Further research is needed to understand the physical mechanisms and implications of seeding effects on different echo types.
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