The X-Ray Sensor (XRS) on the Geostationary Orbiting Environmental Satellite (GOES) provides a standard reference for essentially continuous monitoring solar activity and characterizing solar flares. Disk-integrated x-ray fluxes observed by XRS are used by forecasters and researchers around the world as a measure of the strength and duration of solar flares. The peak 0. 1-0.8 am x-ray flux during flares is used to distinguish between C, M, and X flares, flares that differ by an order of magnitude in the peak flux. Forecasters use this peak flux to predict the magnitude of proton events, and the x-ray duration is used to estimate whether coronal mass ejection may have occurred that could cause a geomagnetic disturbance if it hits the Earth. Recipients of the data use the peak flux and the duration of the flare to estimate the disturbances expected on radio communication systems. The magnitudes of XRS-observed flares are also used to determine when to issue alerts of changed ionospheric conditions that can disrupt communications and GPS signals. XRS fluxes are also used to augment solar radio observations to alert users of radio frequencies of times when the solar signal may interfere with their operations. The nonflaring x-ray flux, otherwise known as the x-ray background flux, is used as a proxy for the solar EUV emissions that are used to predict the atmospheric density as satellite orbits; variations in the daily averaged solar x-ray flux are used to estimate changes in the atmospheric drag on spacecraft orbits.
Missing data for key efficacy and safety endpoints in clinical trials have the potential to undermine the scientific integrity of the study and prevent definitive conclusions regarding the safety and efficacy of an experimental product. Much of the missing data is the result of poor protocol design and a lack of agreement in the scientific community regarding the collection of study data after treatment discontinuation instead of an inability to collect the data. Rather than dealing with the fundamental causes of missing data, the statistical community has traditionally attempted to explicitly impute the missing data based upon observed data or more recently through the use of statistical models that implicitly impute the missing data. In this article, the causes for missing data are described and a number of approaches to maintain the integrity of the studies are described.
Space Environment Center (SEC) is the United States' official source of space weather alerts, warnings, and forecasts. Forecasts are used to support activities that are impacted by space weather such as electric power transmission, satellite operations, humans in space, navigation, and communication. This article presents a brief review of current space weather forecasting capabilities, and then focuses on the science, the models, the data, the new technologies, and the process for tran sitioning research into operations that is needed to meet the challenge to improve space weather forecasting in the new millennium. Forecasting critical parameters such as the interplanetary magnetic field at the magnetopause, and critical events such as coronal mass ejections are two examples of challenges to the research, ob servation, and modeling communities. Major improvements in space weather fore casting will be achieved when these, as well as other, challenges are met. The forecasting challenge is also discussed in the context of the goals of the US Na tional Space Weather Program (NSWP) and other international activities.
The mission ofthe NOAA Space Environment Center (SEC) is to serve the nation's need to reduce adverse effects of solar-terrestrial diswrbances on humankind's activities. To meet this need, SEC . acquires, interprets, and disseminates space weather information . prepares and disseminates forecasts and alerts of conditions ofthe space environment . conducts research and development in solar-terrestrial physics and in techniques to improve monitoring and forecasting. prepares high quality data for national archives . uses its expertise to advise and educate those affected by variations in the space environment.Users are provided information in the form offorecasts, nowcasts, data, advice, support, expertise, and publications about conditions in the solar-terrestrial environment. The Space Environment Monitors on GOES spacecraft provide space weather observations from the Sun to Earth and form the basis ofthe SEC real-time operation. The X-ray Sensor (XRS) monitors solar flare activity and serves as the international standard for rating the intensity of flares. Flares are observed and classified according to the intensity oftheir emission on the XRS sensor. Forecasts of the occurrence of solar flares are expressed in terms ofthe measurements from the XRS. SEC also issues a daily index ofthe background solar radiation based on the XRS measurements. Solar particle events (SPE) and energetic electron events (increases in the charged particle radiation environment near Earth) are detected using the Energetic Particle Sensors (EPS) on GOES. Alerts and forecasts ofthe occurrence of SPE are made in terms of the fluxes ofcharged ions-mostly protons-measured by the EPS. Alerts are issued for energetic electron events based on the EPS measurements.
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