Solar parameters for modeling interplanetary background

The goal of the Fully Online Datacenter of Ultraviolet Emissions (FONDUE) Working Team of the International Space Science Institute in Bern, Switzerland, was to establish a common calibration of various UV and EUV heliospheric observations, both spectroscopic and photometric. Realization of this goal required an up-to-date model of spatial distribution of neutral interstellar hydrogen in the heliosphere, and to that end, a credible model of the radiation pressure and ionization processes was needed. This chapter describes the solar factors shaping the distribution of neutral interstellar H in the heliosphere. Presented are the solar Lyman-alpha flux and the solar Lyman-alpha resonant radiation pressure force acting on neutral H atoms in the heliosphere, solar EUV radiation and the photoionization of heliospheric hydrogen, and their evolution in time and the still hypothetical variation with heliolatitude. Further, solar wind and its evolution with solar activity is presented in the context of the charge exchange ionization of heliospheric hydrogen, and in the context of dynamic pressure variations. Also the electron ionization and its variation with time, heliolatitude, and solar distance is presented. After a review of all of those topics, we present an interim model of solar wind and the other solar factors based on up-to-date in situ and remote sensing observations of solar wind. Results of this effort will further be utilised to improve on the model of solar wind evolution, which will be an invaluable asset in all heliospheric measurements, including, among others, the observations of Energetic Neutral Atoms by the Interstellar Boundary Explorer (IBEX).Comment: Chapter 2 in the planned "Cross-Calibration of Past and Present Far UV Spectra of Solar System Objects and the Heliosphere", ISSI Scientific Report No 12, ed. R.M. Bonnet, E. Quemerais, M. Snow, Springe

Study of sporadic-E clouds by backscatter radar

It is shown that swept-frequency backscatter ionograms covering a range of azimuths can be used to study the dynamics of sporadic-E clouds. A simple technique based on analytic ray tracing can be used to simulate the observed narrow traces associated with Es patches. This enables the location and extent of the sporadic-E clouds to be determined. The motion of clouds can then be determined from a time sequence of records. In order to demonstrate the method, results are presented from an initial study of 5 days of backscatter ionograms from the Jindalee Stage B data base obtained during March-April 1990. Usually 2–3 clouds were observed each day, mainly during the evening and up to midnight. The clouds lasted from 1–4 h and extended between 30°–80° in azimuth and 150-800 km in range. The clouds were mostly stationary or drifted generally westward with velocities of up to 80 m s–1. Only one cloud was observed moving eastward

DIAS effective sunspot number as an indicator of the ionospheric activity level over Europe

DIAS (European Digital Upper Atmosphere Server) effective sunspot number – R12eff was recently introduced as a proxy of the ionospheric conditions over Europe for regional ionospheric mapping purposes. Although a pre-processing step for the real-time update of the Simplified Ionospheric Regional Model (SIRM) to real-time conditions, R12eff is available in real time by DIAS system (http://dias.space.noa.gr) for independent operational use. In this paper we discuss the efficiency of R12eff to specify ionospheric conditions over Europe. For this purpose, the diurnal R12eff’s reference pattern was determined on monthly basis and for different solar cycle phases. The deviation of the real-time R12eff estimates from the reference values, ΔR12eff was found to be highly correlated with the foF2 storm-time disturbances, especially during large scale effects indicating that DIAS-R12eff can provide a reliable estimator of the ionospheric activity level over a substantial part of Europe and a powerful tool for ionospheric specification applications.Published491-5121.7. Osservazioni di alta e media atmosfera3.9. Fisica della magnetosfera, ionosfera e meteorologia spazialeJCR Journalrestricte