This data set contains the coefficients for the foF2 and M(3000)F2 models recommended by the Comité Consultatif International des Radiocommunications (CCIR). foF2 is the F2-peak plasma frequency, which is related to the F2-peak density NmF2 by
NmF2/m-3 = 1.24 * 1010 (foF2/MHz)2.
M(3000)F2 (= MUF(3000)/foF2) is a propagation factor closely related to the height of the F2-peak (see Bilitza et al., 1979). MUF(3000) is the highest frequency that, refracted in the ionosphere, can be received at a distance of 3000 km. Both parameters foF2 and M(3000)F2 are routinely scaled from ionograms. The CCIR maps are based on monthly median values obtained by the worldwide network of ionosondes (about 150 stations) during the years 1954 to 1958, altogether about 10,000 station-months of data. Following a numerical mapping procedure developed by Jones and Gallet (1962, 1965), each station data set is first represented by a Fourier time series (in Universal Time), and then a worldwide development in a special form of Legendre functions (in geodetic latitude, longitude, and modified dip latitude) is applied for each Fourier coefficient. Coefficients sets are provided for high and low solar activity. For intermediate levels of solar activity, linear interpolation is suggested. The whole CCIR model consists of (988 + 441) * 2 * 12 = 34,296 coefficients.
Availability: This data set is included in the International Reference Ionosphere.
W. B. Jones and R. M. Gallet, The Representation of Diurnal and Geographic Variations of Ionospheric Data by Numerical Methods, Telecomm. J. 29, 129, 1962, and 32, 18, 1965.
CCIR Atlas of Ionospheric Characteristics, Comité Consultatif International des Radiocommunications, Report 340-4, International Telecommunications Union, Geneva, 1967.
W. B. Jones and D. L. Obitts, Global Representation of Annual and Solar Cycle Variation of foF2 Monthly Median 1954-1958, U.S. Institute for Telecommunication Sciences, Research Report OT/ITSRR 3, National Technical Information Service, COM 75-11143/AS, Springfield, Virginia, 1970.
D. Bilitza, N. M. Sheikh, and R. Eyfrig, A Global Model for the Height of the F2-Peak Using M(3000)F2 Values from the CCIR Numerical Map, Telecomm. J. 46, 549, 1979.
P. A. Bradely, Mapping the Critical Frequency of the F2-Layer: Part 1-Requirements and Developments to Around 1980, Adv. Space Res. 10, #8, 47, 1990.