Perturbation Pressure Variations Deduced from Earthscope's US Array

University Of Utah, Salt Lake City UT

Investigators

Abstract

Observations of surface pressure perturbations have been used for decades to understand gravity waves, convective processes, and terrain-flow interactions. While pressure perturbations on all scales have been studied, there is a research gap between the emphasis on low amplitude, high frequency perturbations arising typically from local turbulent boundary layer processes and large amplitude, lower frequency ones that can propagate over large distances and often lead to damaging winds. The pressure perturbations and pressure gradients leading to wind ramps that affect wind energy tend to fall between these two extremes. This research will take advantage of the deployment beginning in 2010 of pressure sensors on the NSF sponsored Earthscope seismic Transportable Array (US Array). The sensors were initially in the central United States and now beginning to be deployed after two years to the eastern United States. These pressure data at a sampling interval of 1 Hz at ~400 stations will be used to document pressure perturbations on temporal scales from seconds to days and spatial gradients and wave-like characteristics of such perturbations on spatial scales larger than ~150 km. The specific objectives of this study are: (1) Improve access for the atmospheric research community to pressure data acquired by the US Array; (2) Develop climatologies at each observing site of pressure perturbations in terms of frequency and amplitude as a function of location, season, and time of day; (3) Assess the amplitudes of horizontal perturbation pressure gradients in the context of local, mesoscale, and synoptic-scale flows; (4) Determine regional differences in the characteristics of propagating pressure perturbations; and (5) Examine pressure perturbations arising from terrain-flow interactions and thermally forced systems. The local and regional climatologies, case studies, and composites generated as part of this study will be used to examine the interactions of the many physical processes leading to pressure perturbations, i.e., solar tides, mountain-flow interactions, convective systems, ducted gravity waves, water breeze systems, etc. Intellectual Merit: This research may potentially advance knowledge and understanding of the numerous physical processes that lead to the redistribution of mass in the atmosphere. While there has been considerable work on how surface pressure perturbations are generated and their impacts, there has no any systematic study of pressure perturbations over the broad range of relevant temporal scales (seconds to days) over a large region (in this case, the eastern half of the United States). This research and the knowledge gained from the study will be applicable to similar phenomenon around the world. The project builds on familiarity with the US Array project, computer science expertise in data analysis, mining, and visualization, and prior research in statistical analysis, data assimilation, water breeze systems, and boundary-layer processes in mountainous terrain. Broader Impacts: Improved access to the US Array pressure data will lead to increasing collaboration among researchers interested in a broad spectrum of research arising from applications of these data. Benefits for society at large include improved nowcasting and prediction of severe storms arising from many different types of weather situations and better utilizations of wind energy resources. The research and teaching activities of the lead PI are closely related and enable the direct infusion of research findings into undergraduate and graduate courses at the University of Utah and elsewhere. The project involves the support and mentoring of a postdoctoral fellow and a doctoral student.