Representation of diurnal and geographic variations of ionospheric data by numerical methods

Abstract

A solut ion is given to the problem of r epresentin g the complex proper ties of ionospheri c cha racteristics on a worldwide scale, including their diurnal variation, by num eri cal analysis of ionospher ic data as t h ey a re obtained fr om a n etwork of so undin g statio ns, wit hout prior han d operations. The problem is co mpli cated by t wo bas ic diffi culties : (1) t he da ta ar e affected by noise (ran do m fiuctuation) an d (2) t he stations ar e irreg ularl y posit ion ed in t h e two s pace dim ens ions. The seco nd diffi culty is over co me by a gener al met hod for constructing fun ctions orthogonal relative to the dist ri bution of t he sta t ions . S pccial filterin g p ro cesses a re employed for t hc optimum separation of noise fr om real p hys ical var iat ions . The en d produ ct of t he a na lys is is a table of numerical coeffi cie nts de finin g a fun ction r (A, 0, I) of t hr ec variables, latit ud e (i--) , longitude (0) and ti me (I) , w hich can be used to compute t he io nospheri c characte ristic at a ny des ir ed location or instant of t ime. The method a pplies to a ny io nospheri c characte ristic; however, a s a means of illus tration we use in t h e p resent p a p er only t he characterist ic, monthly med ian of t he F2-laye r cri t ical fr eq uency (fo F,).December 1957 96 stations.

Some Characteristics of the Ionospheric Behavior During the Solar Cycle 23 – 24 Minimum

“…The maximum frequency reflected is known as the F-region critical frequency (foF2). The relation between the plasma frequency foF2 and the electron density NmF2 at the F peak can be expressed as NmF2 [m −3 ] = 1.24 × 10 10 foF2 2 [MHz] (Jones and Gallet, 1962).…”

Pressure-density-temperature relations of fluid para hydrogen from 15 to 100 °K at pressures to 350 atmospheres

“…9001 9002 9003 9004 9005 9006 9007 9008 900'1 90 10 9011 90 1 2 9013 9014 9015 9016 9017 9018 9019 9020 9021 9022 9023 9024 9025 9025 9026 9028 9029 Ident. 8701 8102 8703 8704 8 70 5 8106 8707 8708 A709 8710 8711 8712 8113 8714 · 8715 8716 8717 8718 8719 8720 8721 8722 8723 8724 8725 T, OK 2 5 26 27 28 29 3 0 31 32 33 34 35 36 37 3 8 39 4 Ident Y20 1 9202 9203 9204 9205 9 206 C;207 9208 92 0 9 92 10 9211 9212 9213 9214 92 15 f.l2 } 6 ExpcrilllenLal isotherm fun ctions (Pv-RT )v , wh crc v is molal volum e, were r epresented by polyHomi l.l cxpansions in density [18], using least-squares Ill eLhods [19] and an electronic computer with eleven cI igi ls. The nUIll b el' of terms in each polynomial was sclected by trial as the minimum llmnbcr required Lo give deviations within experim ental precision [7].…”

“…Thomas R. Strobridge kindly gave to us his computer program [22] of the least-squares method of William B. Jones [19]. Among present authors, the preparation, examination, and interpolation of isot herm polynomials was carried through by L. A. Weber and H. M. Roder.…”

Instantaneous space‐weighted ionospheric regional model for instantaneous mapping of the critical frequency of the F2 layer in the European region

“…The statistical description of the ionosphere is carried out with the monthly median (defined as the data point with an equal number points below it and above it) that, because of the large spread of the hourly values of the ionospheric parameters, is more suitable for describing the average behavior of the ionosphere than the standard mean. Over the years, a large number of global [Jones and Gallet, 1962; Comite Consultatif International des Radiocommunications (CCIR), 1991; International Telecommunication Union (ITU), 1997] and regional models [Bradley, 1999;Hanbaba, 1999] have been developed. These models provide long-term predictions of the monthly medians of the standard ionospheric parameters, offering good guidelines for the choice of the frequencies that need be used in HF communications under ''quiet'' ionospheric conditions.…”