Collaborative Research to Explore the Spatial/Temporal Statistical-Physical Structures of Rain in the Vertical Plane

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A good understanding of rain in time and space is important for improved public safety and productivity. With regard to public safety, this means better water control designs for reducing the impact of flooding from smaller urban to larger regional scales as well as for improved spatial and temporal warnings of flooding in order to reduce damage and fatalities. With regard to productivity in rural areas, such information has the potential for reducing the impacts of soil erosion through the better design of field run-off and water storage. In more urban areas, productivity depends in part upon good wireless communication. However, the advent of 5G wireless networks will be more subject to signal loss due to rain, a loss that also depends upon the largely unknown spatial structure of rainfall particularly above the ground. All of these improvements, however, depend upon the proper translation of radar measurements and numerical model outputs to many different scales. This in turn requires that radar measurements above the ground as well as numerical model products be correctly transferred to what appears at the surface where people live. This, then, is a central objective of this project.More specifically with regard to the science, this project allows a more complete description of rain structure in a multi-dimensional context including height with the additional benefit of developing a better multi-dimensional understanding of drop interactions and evolution. Furthermore, the project is directed toward a more comprehensive investigation into the prevalence and the importance of statistical homogeneity in all three spatial dimensions as well as in time. Statistical homogeneity is important for the proper scaling of rainfall measurements, but, of course, not all rain is statistically homogeneous. However, it often appears that when the data are statistically heterogeneous, such data may be subdivided into statistically homogeneous sections which can then be properly treated analytically. This project develops this approach. In addition, wind tower measurements as well as simultaneous measurements between two 2DVD disdrometers will be used to explore further the reported deviations of drop fall speeds from their nominal terminal values both aloft and at the surface. This is potentially quite important for the proper understanding of the evolution of rain.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.