The National Mosaic and Multi-sensor QPE (Quantitative Precipitation Estimation), or “NMQ”, system was initially developed from a joint initiative between the National Oceanic and Atmospheric Administration's National Severe Storms Laboratory, the Federal Aviation Administration's Aviation Weather Research Program, and the Salt River Project. Further development has continued with additional support from the National Weather Service (NWS) Office of Hydrologic Development, the NWS Office of Climate, Water, and Weather Services, and the Central Weather Bureau of Taiwan. The objectives of NMQ research and development (R&D) are 1) to develop a hydrometeorological platform for assimilating different observational networks toward creating high spatial and temporal resolution multisensor QPEs for f lood warnings and water resource management and 2) to develop a seamless high-resolution national 3D grid of radar reflectivity for severe weather detection, data assimilation, numerical weather prediction model verification, and aviation product development. Through about ten years of R&D, a real-time NMQ system has been implemented (http://nmq.ou.edu). Since June 2006, the system has been generating high-resolution 3D reflectivity mosaic grids (31 vertical levels) and a suite of severe weather and QPE products in real-time for the conterminous United States at a 1-km horizontal resolution and 2.5 minute update cycle. The experimental products are provided in real-time to end users ranging from government agencies, universities, research institutes, and the private sector and have been utilized in various meteorological, aviation, and hydrological applications. Further, a number of operational QPE products generated from different sensors (radar, gauge, satellite) and by human experts are ingested in the NMQ system and the experimental products are evaluated against the operational products as well as independent gauge observations in real time. The NMQ is a fully automated system. It facilitates systematic evaluations and advances of hydrometeorological sciences and technologies in a real-time environment and serves as a test bed for rapid science-to-operation infusions. This paper describes scientific components of the NMQ system and presents initial evaluation results and future development plans of the system.

Aircraft measurements taken during the North American Research Strategy for Tropospheric Ozone-Northeast field study reveal the presence of ozone concentration levels in excess of 80 ppb on a regional scale in the nocturnal residual layer during ozone episodes. The air mass containing increased concentrations of ozone commonly is found on a horizontal spatial scale of about 600 km over the eastern United States. The diurnal variation in ozone concentrations at different altitudes, ozone flux measurements, and vertical profiles of ozone suggest that ozone and its precursors trapped aloft in the nocturnal residual layer can influence the ground-level ozone concentrations on the following day as the surface-based inversion starts to break up. A simple onedimensional model, treating both meteorological and chemical processes, has been applied to investigate the relative contributions of vertical mixing and photochemical reactions to the temporal evolution of the groundlevel ozone concentration during the daytime. The results demonstrate that the vertical mixing process contributes significantly to the ozone buildup at ground level in the morning as the mixing layer starts to grow rapidly. When the top of the mixing layer reaches the ozone-rich layer aloft, high ozone concentrations are brought down into the mixing layer, rapidly increasing the ground-level ozone concentration because of fumigation. As the mixing layer grows further, it contributes to dilution while the chemical processes continue to contribute to ozone production. Model simulations also were performed for an urban site with different amounts of reduction in the ground-level emissions as well as a 50% reduction in the concentration levels of ozone and its precursors aloft. The results reveal that a greater reduction in the ground-level ozone concentration can be achieved by decreasing the concentrations of ozone and precursors aloft than can be achieved from a reduction of local emissions. Given the regional extent of the polluted dome aloft during a typical ozone episode in the northeastern United States, these results demonstrate the necessity and importance of implementing emission reduction strategies on the regional scale; such regionwide emission controls would reduce effectively the long-range transport of pollutants in the Northeast.

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