Showing papers by "American Meteorological Society published in 2003"

Understanding climatic impacts, vulnerabilities, and adaptation in the united states: building a capacity for assessment

Abstract: Based on the experience of the U.S. National Assessment, we propose a program of research and analysis to advance capability for assessment of climate impacts, vulnerabilities, and adaptation options. We identify specific priorities for scientific research on the responses of ecological and socioeconomic systems to climate and other stresses; for improvement in the climatic inputs to impact assessments; and for further development of assessment methods to improve their practical utility to decision-makers. Finally, we propose a new institutional model for assessment, based principally on regional efforts that integrate observations, research, data, applications, and assessment on climate and linked environmental-change issues. The proposed program will require effective collaboration between scientists, resource managers, and other stakeholders, all of whose expertise is needed to define and prioritize key regional issues, characterize relevant uncertainties, and assess potential responses. While both scientifically and organizationally challenging, such an integrated program holds the best promise of advancing our capacity to manage resources and the economy adaptively under a changing climate.

Constrained tracking filters for A-SMGCS

Abstract: The Advanced Surface Movement Guidance and Control System (A-SMGCS) requirements are challenging because airports have many shadowing problems, targets with dgferent dynamics and minimal spatial separation, heavy clutter and multipath. This paper illustrates a new approach to the tracking applied to the data of the SMR (Surface Movement Radar) based on Variable Structure Interactive Multiple Model (VS- IMW which uses the airport map data. On the airport the target movement is in fact locally constrained by roads and runways, while in proximity of junctions the targets have a limited numbers of manoeuvres. The improvement brought by the VS-IMM with respect to the classical tracking algorithm has been demonstrated by simulation results and application to real data.

Stark-ladder resonances in piezoelectric composites

Abstract: In this paper we introduce a piezoelectric composite medium. The composite shows a series of resonances similar to the Stark-ladder resonances originally observed in the propagation of electrons through crystals in a dc electric field. These resonances appear when shear horizontal and surface waves propagate through a special piezoelectric composite medium consisting of N piezoelectric layers, each layer being a material of hexagonal 6mm symmetry. For periodic piezocomposites, we obtain a band structure as expected. However, when the periodicity is broken by adding a linear term in the values of the piezoelectric parameters of the layers, the band structure is destroyed and, in certain cases, resonances of Stark-ladder type appear instead. A 4×4 transfer matrix approach is used to calculate the response of the composite under electromechanical perturbations. The response is studied as a function of the properties of the different materials, width of the layers, wave frequency, and angle of incidence. Numerical results for the electric potential and for the displacement of the surface of the last layer of the composite are presented showing the existence of Stark-ladder resonances.

Integrating Space Weather and Meteorological Products for Aviation

Abstract: NOVEMBER 2003 AMERICAN METEOROLOGICAL SOCIETY | ne might think that solar flares, coronal mass ejections, and geomagnetic storms are phenomena that only interest space scientists. However, conditions on the sun, in the solar wind, and within the Earth’s magnetic field, otherwise known as “space weather,” can affect a wide variety of ground and space technologies. For example, solar and geomagnetic events can impact satellite operations, navigation, space shuttle and space activities, high-altitude polar flights, electric power distribution, long-line telephone communication, high-frequency (HF) radio communication, and geophysical exploration. As the nation’s reliance on technological systems grows, so does our vulnerability to space weather. The aviation industry is just one of the many user groups that are trying to understand how space weather impacts their operations and what can be done to mitigate disruptions. Airlines are becoming more concerned with flying transpolar routes, losing HF communication, radiation hazards to crews, and the possibility of global positioning system (GPS) errors. Many space weather hazards can be mitigated or avoided if reliable space weather forecasts are available. In response to this need, the federal government has formed the National Space Weather Program, an interagency program under the auspices of the Office of the Federal Coordinator for Meteorology started in 1994, to “achieve an active, synergistic interagency system to provide timely, accurate, and reliable space environment observations, specification, and forecasts.” Currently, space environmental support services are provided by the NOAA Space Environment Center (SEC) and the U.S. Air Force (USAF), which jointly operate the Space Weather Operations (SWO) Forecast and Analysis Center. It is the national and world warning center for disturbances that can affect people and equipment working in space, and provides forecasts, warnings, and alerts of solar and geomagnetic activity to users in government, industry, and the private sector. NOAA/SEC is the official source of space weather alerts and warnings for commercial and public sector customers. INTEGRATING SPACE WEATHER AND METEOROLOGICAL PRODUCTS FOR AVIATION

Geometry of the group of nonzero quaternions

Abstract: It is shown that the group of nonzero quaternions carries a family of natural closed Friedmann-Lema\^{\i}tre-Robertson-Walker metrics