DOI: 10.21227/19sy-y827
title: Dataset of IAR harmonic frequencies and their ratios

description: README File for Dataset of IAR harmonic frequencies and their ratiosTitle of submitted article:“Ratio between discrete IAR frequencies from observations in the solar cycle 24,” by A.S. Potapov, A.V. Guglielmi, and B.I. KlainDescription of the processing method:The dataset is a table of the observed frequencies of IAR harmonics measured from daily spectrograms. The initial data are the diurnal dynamic IAR spectra recorded at the mid-latitude Mondy station (51.6 N, 100.9 E) during the solar cycle 24  (2009–2019). IAR emission spectrograms are a fan-shaped set of bands, the frequency of which varies during the day (see Fig. 2 in the submitted article). Each of the bands corresponds to one of the harmonics of the resonator emission. The width of the bands, i.e., their blurring, which reflects the quality factor of the resonator, also changes. The clearest and narrowest bands are usually observed in the afternoon and evening hours of local time. Exact measurement of the frequency ratio of the resonant bands is hampered, in addition to blurring, by the difficulty of determining the frequency of the first harmonic. The fact is that its frequency lies in the range of fractions of a hertz, where it can merge with the background formed by various kinds of low-frequency oscillations (geomagnetic pulsations). To overcome these difficulties, we made a preliminary selection of spectrograms. For subsequent analysis, the following procedure of material selection was applied. At the beginning of each year of the cycle, 12 days were selected, the spectrograms of which contained sections of rather narrow spectral bands and a clearly expressed first harmonic. (The exception was 2009, where 12 days were selected at the end of the year due to the lack of records at its beginning.) The winter months were chosen because at this season, in accordance with the seasonal course of the amplitude and duration of the IAR emission the most favorable conditions for observing resonance bands are formed. On each of the selected spectrograms, an hour mark was being found, above which at least five harmonics, including the first, were most clearly traced. The frequencies of these harmonics were measured. This method of processing of experimental material made it possible to obtain 132 sets of frequency ratios of the first five harmonics. In addition, the obtained data made it possible to check whether there is a dependence of the typical harmonic frequency ratios on the phase of the solar cycle.Description of the dataset table:The table consists of 11 blocks, each includes data for one of the solar cycle 24 years.Columns 1 and 20 contain year numbers and 12 dates of the frequencies measurement for each year. All dates lie within the beginning part of each year (January or February). Exclusion is 2009 with dates within December and November.Column 2 indicates the magnetic field component used for measurement.Columns 3 and 4 contain universal and local time of the measurements.Columns 5–9 are the frequency values of the first five IAR harmonics, from 1st to 5th.Columns 10–19 contain ratios between the frequencies of all 5 measured harmonics.Column 21 shows values of determinant calculated from the measured frequency ratios.Each year block has the upper line with designations of the columns and two bottom lines with the mean and standard deviations values of all frequencies and their ratios for the given year.