| 英文摘要: | The general objective is to conduct hypothesis-driven research to improve understanding of the physics of convergent boundary zones (CBZ) over the Great Plains, focusing on the stable nocturnal boundary layer (NBL), within which the evolution of CBZs, convective initiation (CI), and maintenance of mesoscale convective systems (MCSs) is poorly understood. The significant societal benefits of this research are improved forecasting of CI, lightning, severe weather (tornadoes), and air quality.
Three primary and closely related objectives include comprehensive investigations of:
1. Characteristics of CBZs (e.g., gust fronts, bores, solitary waves) within the stable NBL, including the sources and evolution of bores and waves, and their impact on cloud formation, CI, and maintenance of MCSs;
2. CBZ kinematics, evolution, and CI during the Afternoon to Evening Transition(AET);
3. Evaluation of the accuracy of airflow derived from Doppler radars and profilers within the NBL. This project is fully integrated with the multi-agency Plains Elevated Convection at Night (PECAN) field campaign centered over the Kansas, to be conducted between 1 June and 15 July 2015. The research team will be actively involved in the field campaign by contributing three UAH facilities: the Mobile Integrated Profiling System (MIPS), the Mobile Alabama X-band (MAX) dual polarization radar (MAX), and a mobile mesonet. These facilities will be part of a proposed mesoscale network of instrumentation including 8 mobile radars, 4 mobile profiling systems, and 6 fixed-site profiling systems over the PECAN domain. Results of this project will be compared to those of the ABIDE project (in a much different environment) in order to determine the relative importance of the low level jet on nocturnal CBZs (bores and waves in particular), CI, and MCS maintenance over the Great Plains.
Intellectual merit. This project will contribute to advances in our understanding of the physics of CBZs and CI by examining these phenomena in a parameter space (neutral to stable) that has not previously been comprehensively explored over the Great Plains. The unique feature of this project is its emphasis on the behavior of deep convection and MCSs in the stable NBL, and involves a continuation of the ABIDE project that has provided observations on many of the phenomena of importance to the PECAN project. Thus we have gained appreciable insight on the phenomena of interest (forcing and maintenance of deep convection in the NBL) that will contribute to the success of the PECAN field campaign. The PI has been conducting research on deep convection utilizing the MIPS instrumentation for much of his career. We have gained considerable expertise in conducting mobile operations and analysis of data from a diverse array of profiler and radar platforms, like those to be employed in this study.
Broader impacts. Improved forecasting of CI, lightning, severe weather (tornadoes), and BL transports (air quality) represent significant societal benefits of this research. The central Great Plains is noted for the nocturnal maximum in thunderstorm and MCS activity that provides a significant fraction of rainfall to this region during the warm season. The comprehensive nature of measurements (and the 24/7 capability of many of the PECAN resources) increases probability of serendipitous discoveries, which is an important component of advancing scientific discovery. The data collected during the PECAN field campaign will be utilized extensively in (i) two graduate level courses, Boundary Layer Meteorology and Ground-Based Remote Sensing; and (ii) a book Ground-Based Remote Sensing. Two UAH graduate students and one postdoctoral associate will be actively engaged in all aspects of the field campaign and subsequent analysis activities. As in the past, the UAH platforms will be made available to other UAH students who have research interests in related topics. The project will support and utilize the MIPS and MAX, the former of which has been operated in numerous scientific projects over the past 15 years. The data sets will contribute to other disciplines, such as mesoscale/microscale structure of fronts, gravity waves in the severe storms environment, boundary layer processes (AET and NBL in particular), and properties of biological flyers and their impact on accuracy of winds retrieved from Doppler radars and radar wind profilers. |