Scaled Ionospheric Data Format
The scaled ionospheric parameter yearly data file downloaded from ASWFC website has files of the form:
SSSSPP.YY.gz
where:
- SSSS = ASWFC Station Number, listed in following table
- PP = URSI parameter code, listed in following table
- YY = Year
- gz = gzip file extension
The data format for each ASWFC record in a yearly file is as follows.
| Character position | Content |
|---|---|
| 1-4 | ASWFC Station Number |
| 5-6 | URSI Parameter Code |
| 7-12 | year, month, day (YYMMDD) |
| 13-132 | 24 space-separated hourly values (QVVVD) where Q=qualifier, VVV=value, D=descriptor |
The hourly values are in universal time (UT). The first hour of each record is 0000 UT.
Note: Macquarie Island data from 1950 - 1958 is in local time (LT) (157.5 EMT, or 10.5 hours ahead of 00 UT). The first hour of each record for this period is 0000 LT (midnight).
Following is a summary of ASWFC ionosonde stations.
| ASWFC station number | Station name | Latitude | Longitude | Local mean time |
|---|---|---|---|---|
| 3038 | Manila | 14.70 | 121.10 | |
| 3546 | Vanimo | -2.70 | 141.30 | 150 |
| 3750 | Port Moresby | -9.40 | 147.10 | 150 |
| 2451 | Cocos Islands | -12.20 | 96.80 | 90 |
| 3351 | Darwin | -12.45 | 130.95 | 135 |
| 4755 | Niue | -19.07 | 190.07 | |
| 3755 | Townsville | -19.63 | 146.85 | 150 |
| 3355 | Tennant Ck | -19.65 | 134.25 | 135 |
| 2856 | Learmonth | -22.25 | 114.08 | 120 |
| 3357 | Alice Springs | -23.81 | 133.90 | 135 |
| 3859 | Brisbane | -27.53 | 152.92 | 150 |
| 4260 | Norfolk Is | -29.03 | 167.97 | 180 |
| 2960 | Watheroo | -30.30 | 115.90 | 120 |
| 3460 | Woomera | -30.80 | 136.30 | 135 |
| 2961 | Mundaring | -31.98 | 116.22 | 120 |
| 2962 | Perth | -31.94 | 115.95 | 120 |
| 3862 | Camden | -34.05 | 150.67 | 150 |
| 3562 | Salisbury | -34.70 | 138.60 | 135 |
| 3763 | Canberra | -35.32 | 149.00 | 150 |
| 3766 | Hobart | -42.92 | 147.32 | 150 |
| 4072 | Macquarie Is | -54.50 | 158.95 | 150 |
| 2878 | Casey | -66.30 | 110.50 | 105 |
| 1679 | Mawson | -67.60 | 62.88 | 60 |
| 1979 | Davis | -68.58 | 77.96 | 75 |
The URSI parameter codes are defined as follows.
| Code | Parameter | Units | Ref. UAG23 | Definition |
|---|---|---|---|---|
| 00 | foF2 | 0.1 MHz | 1.11 | Ordinary wave critical frequency of the highest stratification in the F region |
| 01 | fxF2 | 0.1 MHz | 1.11 | Extraordinary wave critical frequency |
| 02 | fzF2 | 0.1 MHz | 1.11 | Z-mode wave critical frequency |
| 03 | M(3000)F2 | 0.01 | 1.50 | Maximum usable frequency at a defined distance divided by the critical frequency of that layer |
| 04 | h'F2 | km | 1.33 | Minimum virtual height of the ordinary wave trace for the highest stable stratification in the F region |
| 05 | hpF2 | km | 1.41 | Virtual height of the ordinary wave mode at the frequency given by 0.834 of foF2 (or other 7.34) |
| 06 | h'Ox | km | 1.39 | Virtual height of the x trace at foF2 |
| 07 | MUF(3000)F2 | 0.1 MHz | 1.5C | Standard transmission curve for 3000 km |
| 08 | hc | km | 1.42 | Height of the maximum obtained by fitting a theoretical h'F curve for the parabola of best fit to the observed ordinary wave trace near foF2 and correcting for underlying ionisation |
| 09 | qc | km | 7.34 | Scale height |
| 10 | foF1 | 0.1 MHz | 1.13 | Ordinary wave F1 critical frequency |
| 11 | fxF1 | 0.1 MHz | 1.13 | Extraordinary wave F1 critical frequency |
| 12 | not used | |||
| 13 | M(3000)F1 | 0.01 | 1.50 | Maximum usable frequency at a defined distance divided by the critical frequency of that layer |
| 14 | h'F1 | km | 1.30 | Minimum virtual height of reflection at a point where the trace is horizontal |
| 15 | not used | |||
| 16 | h'F | km | 1.32 | Minimum virtual height of the ordinary wave trace taken as a whole |
| 17 | MUF(3000)F1 | 0.1 MHz | 1.5C | Standard transmission curve for 3000 km |
| 18 | not used | |||
| 19 | not used | |||
| 20 | foE | 0.01 MHz | 1.14 | Ordinary wave critical frequency of the lowest thick layer which causes a discontinuity |
| 21 | not used | |||
| 22 | foE2 | 0.01 MHz | 1.16 | Critical frequency of an occulting thick layer which sometimes appears between the normal E and F1 layers |
| 23 | not used | |||
| 24 | h'E | km | 1.34 | Minimum virtual height of the normal E layer |
| 25 | not used | |||
| 26 | h'E2 | km | 1.36 | Minimum virtual height of the E2 layer |
| 27 | not used | |||
| 28 | not used | |||
| 29 | not used | |||
| 30 | foEs | 0.1 MHz | 1.17 | Highest ordinary wave frequency at which a mainly continuous Es trace is observed |
| 31 | fxEs | 0.1 MHz | 1.17 | Highest extraordinary wave frequency at which a mainly continuous Es trace is observed |
| 32 | fbEs | 0.1 MHz | 1.18 | Blanketing frequency of the Es layer |
| 33 | ftEs | 0.1 MHz | Top frequency Es any mode | |
| 34 | h'Es | km | 1.35 | Minimum height of the trace used to give foEs |
| 35 | not used | |||
| 36 | type Es | 7.26 | Characterisation of the shape of the Es trace W type sporadic E was used at the Australian stations between about February and April 1982 in place of H, C, L and F types. | |
| 37 | not used | |||
| 38 | not used | |||
| 39 | not used | |||
| 40 | foF1.5 | 0.01 MHz | 1.12 | Ordinary wave critical frequency of the intermediate stratification between F1 and F2 |
| 41 | not used | |||
| 42 | fmin | 0.1 MHz | 1.19 | Lowest frequency at which echo traces are observed on the ionogram |
| 43 | M(3000)F1.5 | 0.01 | 1.50 | Maximum usable frequency at a defined distance divided by the critical frequency of that layer |
| 44 | h'F1.5 | km | 1.38 | Minimum virtual height of the ordinary wave trace between foF1 and foF1.5 (equals h'F2 7.34) |
| 45 | not used | |||
| 46 | not used | |||
| 47 | fm2 | 0.1 MHz | 1.14 | Minimum frequency of the second order trace |
| 48 | hm | km | 7.34 | Height of the maximum density of the F2 layer calculated by the Titheridge method |
| 49 | fm3 | 0.1 MHz | 1.25 | Minimum frequency of the third order trace |
| 50 | foI | 0.1 MHz | 1.26 | Top ordinary wave frequency of spread F traces |
| 51 | fxI | 0.1 MHz | 1.21 | Top frequency of spread F traces |
| 52 | fmI | 0.1 MHz | 1.23 | Lowest frequency of spread F traces |
| 53 | M3000I | 0.01 | 1.50 | Maximum usable frequency at a defined distance divided by the critical frequency of that layer |
| 54 | h'I | km | 1.37 | Minimum slant range of the spread F traces |
| 55 | not used | (see note below) | ||
| 56 | not used | (see note below) | ||
| 57 | dfs | 0.1 MHz | 1.22 | Frequency spread of the scatter pattern; 7.34 Frequency range of spread fxI-foF2 |
| 58 | not used | |||
| 59 | not used | |||
| 60 | fh'F2 | 0.1 MHz | 7.34 | Frequency at which h'F2 is measured |
| 61 | fh'F | 0.1 MHz | 7.34 | Frequency at which h'F is measured |
| 62 | not used | |||
| 63 | h'mF1 | km | 7.34 | Maximum virtual height in the o-mode F1 cusp |
| 64 | h1 | km | 7.34 | True height at f1 Titheridge method |
| 65 | h2 | km | 7.34 | True height at f2 Titheridge method |
| 66 | h3 | km | 7.34 | True height at f3 Titheridge method |
| 67 | h4 | km | 7.34 | True height at f4 Titheridge method |
| 68 | h5 | km | 7.34 | True height at f5 Titheridge method |
| 69 | H | km | 7.34 | Effective scale height at hmF2 Titheridge method |
| 70 | I2000 | e/cubic cm | 7.34 | Ionospheric electron content Faraday technique |
| 71 | I | e/cubic cm | 7.34 | Total electron content to geostationary satellite |
| 72 | Ixxxx | e/cubic cm | 7.34 | Ionospheric electron content to height xxxx |
| 73 | not used | |||
| 74 | not used | |||
| 75 | not used | |||
| 76 | not used | |||
| 77 | not used | |||
| 78 | not used | |||
| 79 | T | e/cubic cm | 7.34 | Total sub-peak content Titheridge method |
| 80 | FMINF | 0.01 MHz | Minimum frequency of F trace (50 kHz increments) | |
| 81 | FMINE | 0.01 MHz | Minimum frequency of E trace (50 kHz increments). Equals fbEs when E present | |
| 82 | HOM | km | Parabolic E region peak height | |
| 83 | YM | km | Parabolic E region semi-thickness | |
| 84 | QF | km | Average range spread of F trace | |
| 85 | QE | km | Average range spread of E trace | |
| 86 | FF | 0.01 MHz | Frequency spread between fxF2 and fxI | |
| 87 | FE | 0.01 MHz | As FF but considered beyond foE | |
| 88 | fMUF3000 | 0.01 MHz | MUF(D)/obliquity factor | |
| 89 | h'MUF3000 | km | Virtual height at fMUF |
Note: ASWFC uses the codes 55 and 56 for scaling range spread (RS)(55) and frequency spread (FS)(56).
Qualifying Letters:
- A - Less than. Used only when fbEs is deduced from foEs because total blanketing of higher layers is present
- D - Greater than
- E - Less than
- I - Missing value has been replaced by an interpolated value
- J - Ordinary component characteristic deduced from the extraordinary component
- M - Interpretation of measurement questionable because ordinary and extraordinary components are not distinguishable. Used with descriptive letter which shows why components are not distinguishable
- O - Extraordinary component characteristic deduced from the ordinary component
- T - Value determined by a sequence of observations, the actual observation being inconsistent or doubtful
- U - Uncertain or doubtful numerical value
- Z - Measurement deduced from the third magneto-electronic component
Descriptive Letters:
- A - Measurement influenced by, or impossible because of, the presence of a lower thin layer, for example, ES
- B - Measurement influenced by, or impossible because of, absorption in the vicinity of fmin
- C - Measurement influenced by, or impossible because of, any non-ionospheric reason
- D - Measurement influenced by, or impossible because of, the upper limit of the normal frequency range
- E - Measurement influenced by, or impossible because of, the lower limit of the normal frequency range
- F - Measurement influenced by, or impossible because of, the presence of spread echoes
- G - Measurement influenced by, or impossible because the ionisation density of the reflecting layer is too small to enable it to be made accurately
- H - Measurement influenced by, or impossible because of, the presence of stratification
- K - Presence of a particle E layer
- L - Measurement influenced by, or impossible because the trace has no sufficiently definite cusp between the layers
- M - Interpretation of measurement questionable because ordinary and extraordinary components are not distinguishable. Used when interpretation is doubtful and a qualifying letter needed for other reasons (e.g., U, D, E)
- N - Conditions are such that the measurement cannot be interpreted.
- O - Measurement refers to the ordinary component
- P - Measurement influenced by, or impossible because of, the presence of polar spurs
- Q - Measurement influenced by, or impossible because of, the presence of range spread
- R - Measurement influenced by, or impossible because of, attenuation in the vicinity of the critical frequency
- S - Measurement influenced by, or impossible because of, interference or atmospherics
- T - Value determined by a sequence of observations, the actual value or observation being inconsistent or doubtful
- V - Forked trace, which may influence the measurement
- W - Measurement influenced by, or impossible because the echo lies outside the height range recorded
- X - Measurement refers to the extraordinary component
- Y - Lacuna phenomena, severe layer tilt
- Z - Third magneto-electronic component present
For more information about URSI standard, including Qualifying Letters and Descriptive Letters, please read URSI Handbook of Ionogram Interpretation and Reduction (second edition).
