The GPM GV Integrated Precipitation and Hydrology Experiment (IPHEx) in the Southern Appalachians- Focus on Water Cycle Processes
Abstract:IPHEx was the first Ground Validation campaign after the Global Precipitation Measurement Mission (GPM) Core satellite launch in February 2014. Targeted observations were collected to support precipitation retrieval algorithm development, improve the science of rainfall processes, and demonstrate the utility of GPM data for operational hydrology applications. Instrumentation sites were selected to sample the dominant warm season precipitation regimes, which have distinct implications for water storage dynamics, streamflow response, and hillslope stability in the region. IPHEx consisted of two core activities: 1) an extended observing period (EOP) from Oct 2013-14 including, among other sensors, a raingauge network equipped with soil moisture sensors; and 2) an intense observing period (IOP) from May–July of 2014 focusing on 4D mapping of precipitation structure during which research grade sensors including NASA’s NPOL S-band scanning dual-polarization radar were deployed along with all EOP instrumentation.
During the IOP, science flights were conducted with the Scanning L-band Active-Passive (SLAP) instrument to map soil moisture. In addition to available long-term soil moisture, streamflow, and well data observations, grab samples along with surface roughness, soil bulk density and vegetation topology were collected in fields characterized by different physiographic characteristics concurrent with and along the SLAP flight path. To elucidate the role of surface-groundwater interactions, tracer data on groundwater age and transit time were collected. Because of the rocky streambeds in the inner mountain region, groundwater samples were collected from springs with a peristaltic pump to be analyzed by gas chromatography. A hydrologic prediction testbed during the IPHEX IOP issued streamflow, soil moisture, and water table forecasts on a daily basis for 12 headwater basins in the region. All data necessary to implement and operate the hydrologic models in 4 major SE river basins were processed at hourly time-step and at 1 km2 resolution over a 7-year period (2007-2013). Here, a synthesis of IPHEX observations and modeling, an evaluation of GPM precipitation, SLAP soil moisture retrievals and uncertainty quantification will be presented.