VCSI has developed a wonderful working relationship with the Tennessee Valley Authority (TVA) in a project entitled, “Rainfall Measurement Model Reducing Rain Gauge Requirements.” In June 2007 a “Phase I” demonstration rainfall measurement program was initiated to test the feasibility of replacing a significant percentage of the TVA rain gauge network with advanced ARMOR dual-polarimetric radar-based rainfall estimates. This product was initiated for the TVA by VCSI. The primary deliverables for the Phase I demonstration project included gridded 1-6 hourly radar-estimated rainfall data and accumulation algorithms, radar-rain gauge validation algorithm/products, web page development for data access, automated ftp of rainfall products and development of the framework for proceeding with a Phase II extension of the project.
Following successful development and demonstration of gridded ARMOR rainfall products, it was suggested that these products could in effect serve as a “reference” that could be applied to the development of extended rainfall estimation algorithms implemented using NEXRAD radars covering the remainder of the TVA grid. In this way, a transition from ARMOR to predominantly NEXRAD rainfall products would be transparent, and the removal of rain gauges from the TVA network could become more widespread.
Based on the results of the Phase I effort (now termed: “ARMOR Rainfall Estimation Processing System”, or AREPS), the VCSI team expanded the Phase I product application and development to include an algorithm framework that can be applied to the entire Tennessee River Basin. Currently, the expanded rainfall product remains sub-basin specific (as in the current Phase I product), but is created from existing operational WSR-88D NEXRAD radar data. The product was assigned the name “NEXRAD Rainfall Estimation Processing System (NREPS). In Phase II, AREPS continues to be distributed to TVA as part of the transition to NREPS. However, it is envisioned that the AREPS real time distribution requirement for TVA will eventually cease (e.g., during the proposed Phase III) as the product is transitioned to functioning more as a “target of opportunity” reference or “validating” tool for overlapping NREPS product.
This project, currently in Phase III, has been fully funded by TVA. VCSI works in conjunction with NASA and UAH to bring their expertise together for the benefit of this project.