The GPM-GV Integrated Precipitation and Hydrology Experiment (IPHEX) 2014

Ground validation (GV) campaigns before and after the launch of NASA's Global Precipitation Measurement Mission (GPM) Core satellite in early 2014 have been planned to collect targeted observations to support precipitation retrieval algorithm development, to improve the science of rainfall processes, and to demonstrate the utility of GPM data for operational hydrology and water resources applications. The Integrated Precipitation and Hydrology Experiment (IPHEX) centered in the Southern Appalachians and spanning into the Piedmont and Coastal Plain regions of North Carolina seeks to characterize warm season orographic precipitation regimes, and the relationship between precipitation regimes and hydrologic processes in regions of complex terrain. Since 2007, a high elevation tipping bucket rain gauge network has been in place in the Pigeon River Basin (PRB) in the Southern Appalachians and intensive observing periods (IOPs) have been conducted in this and surrounding river basins to characterize ridge-ridge and ridge-valley variability of precipitation using radiosondes, tethersondes, Micro-Rain Radars (MRRs), automatic weather stations and optical disdrometers. Important results from these analyses include the importance of light (<3 mm/hr) rainfall as a baseline freshwater input to the region especially in the cold season, the high frequency of heavy rainfall and severe weather in the warm season, and illuminate the significant spatio-temporal variability of rainfall in this region. IPHEX will consist of two activities: 1) a long-term observing period (LOP) from October 2013 through October 2014 including an extended raingauge network of 60 stations, half of which will be equipped with multiple raingauge platforms, in addition to the fixed regional observing system; a disdrometer network consisting of twenty separate clusters; and two mobile profiling facilities including MRRs; and 2) an intense observing period (IOP) from May–July of 2014 post GPM launch focusing on 4D mapping of precipitation structure during which NASA's NPOL S-band scanning dual-polarization radar, the dual-frequency KA-KU, dual polarimetric, Doppler radar (D3R), four additional MRRs, and up to four X-band radars will be deployed in addition to the long-term fixed instrumentation. During the IOP, the NASA ER-2 and the UND Citation aircraft will be used to conduct high altitude and “in the column” measurements. The ER-2 is equipped with multi-frequency radiometer and radars necessary to obtain observations consistent with the GPM Core satellite, and the UND Citation instruments are dedicated to microphysical characterization. The ground-based instrumentation sites were selected to collect extensive samples of orographic effects on microphysical properties of precipitation, specifically DSDs, for the dominant warm season precipitation regimes in the region: 1) westerly systems including Mesoscale Convective Systems (MCSs) and fronts; 2) southerly and southeasterly convective systems and tropical storms; and 3) convection initiation and suppression and feeder-seeder interactions among fog and multilayered clouds in the inner mountain region. A real-time hydrologic forecasting testbed is planned to be operational during the IPHEX IOP. In preparation for the forecasting testbed, a benchmark project for intercomparion of hydrologic models has been developed (H4SE) in the context of which all data necessary (GIS, atmospheric forcing, land-surface attributes, soil properties, etc) to implement and operate hydrologic models in four major SE river basins (the Savannah, the Catawba-Sandee, the Yadkin-Peedee and the Upper Tennessee) were analyzed and processed at hourly time-step and at 1 km2 resolution over a 5-year period (2007-2012). Data are currently available at http://iphexpratt.duke.edu to all participants. The goal of H4SE is to facilitate implementation of hydrologic models in the IPHEX region to assess the use and improve the utility of satellite-based Quantitative Precipitation Estimates (QPE) for hydrologic applications. Here, we present IPHEX including preliminary results from LOT observations and H4SE.