An Observing System Simulator for GPM Precipitation Products in Regions of Complex Terrain: Initial development and QPE Applications in the Southern Appalachians

In the case of Quantitative Precipitation Estimation (QPE) for hydrological applications, the goal is to close the scale gap between the spatial resolution of coarse data sets (e.g. gridded satellite precipitation products at resolution L×L) and the high-resolution (l×l ; L>>l) necessary to capture the spatial features that determine spatial variability of water flows and water stores in the landscape. Besides spatial sampling, uncertainty in satellite precipitation products also originates from temporal sampling, sensor fidelity, and the retrieval model. In this work, we present an Observing System Simulator (OSS) that generates Level 2 GPM Precipitation Products based on the Next Generation Quantitative Precipitation Estimates (Q2) product adjusted by data from a dense high-elevation raingauge network in the Southern Appalachians (Q2+), and error structure derived from the systematic evaluation of TRMM precipitation products in the region. Subsequently, the simulated GPM precipitation products are integrated with near-real time NWS QPE estimates, and used to force a high-resolution hydrological model for one year period (2008-2009). The utility of GPM products is evaluated against Q2+ and the existing operational QPE based on streamflow forecast skill.