The NASA NPOL and D3R (IMAGE) NASA/Goddard Space Flight Center Caption The NASA NPOL (right) and D3R (left) precipitation radars were deployed south of Waterloo, Iowa, for the Iowa Flood Studies ground measurement campaign. Credit Matt Schwaller / NASA Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.