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How Effective are Effective-SSN Values?


Northern Hemisphere Southern Hemisphere

This page links to plots comparing foF2 calculated from the CCIR foF2 model using the effective SSN values to foF2 observations and 7-day means for a variety of stations. The SSNe values were calculated from observations in the geomagnetic latitude range of -50 to +50 degrees.

The foF2 parameter shown in these plots, and used in generating the effective SSN index, is defined as the highest frequency which will reflect from the main (F2) layer of the ionosphere on a vertical propagation path. It is measured at a number of locations around the world using an instrument known as an ionosonde. The "o" in foF2 indicates that it is for the "ordinary" propagation mode (as opposed to the extraordinary, or "x", mode). More details on this measurement and on ionosondes can be found at the National Centers for Environmental Information (NCEI) ionospheric WWW site.

All plots have the same format as the one shown above. The foF2 observations for the UT day from the station are plotted as + symbols, and the 7-day mean foF2 are plotted as * symbols. The lines are foF2 values calculated from the CCIR foF2 model (the URSI-88 coefficients) using the NWRA global SSNe (black curve), northern-hemisphere SSNe (red curve), and southern-hemisphere SSNe (green curve).

To hourly SSNe24 plot
To 24-day SSNe24 plot


Comparisons are available for the following stations:


Geographic Geomagnetic
Station Name URSI ID Latitude Longitude Latitude Longitude
*TROMSO TR170 69.7 19.0 67.4 102.4
*MURMANSK MM168 69.0 33.0 66.1 113.4
*EIELSON EI764 64.7 212.9 65.7 267.9
*SODANKYLA SO166 67.4 26.6 64.7 107.1
*GAKONA GA762 62.4 215.0 63.7 271.1
*SALEKHARD SD266 66.5 66.5 63.2 142.1
*ALPENA AL945 45.1 276.4 55.5 351.0
*MAGADAN MG560 60.0 151.0 54.8 220.5
*TOMSK TK356 56.5 84.9 53.2 158.8
*MOSCOW MA155 55.5 37.3 52.4 112.2
*MILLSTONE_HILL MHJ45 42.6 288.5 52.0 7.7
*IDAHO_FALLS IF843 43.8 247.3 51.6 312.1
EAREKSON EA653 52.7 185.9 49.3 250.1
BOULDER BC840 40.0 255.0 49.2 322.1
FAIRFORD FF051 51.7 358.5 48.8 77.3
CHILTON RL052 51.6 358.7 48.7 77.4
WALLOPS_IS WP937 37.9 284.5 48.0 1.9
DOURBES DB049 50.1 4.6 46.7 82.0
PRUHONICE PQ052 50.0 14.6 46.4 90.5
MANZHOULI ML449 49.6 117.5 45.1 191.5
SOPRON SO148 47.7 16.1 43.8 91.4
KHABAROVSK KB548 48.5 135.1 43.1 208.2
EGLIN_AFB EG931 30.5 273.5 41.5 346.5
POINT_ARGUELLO PA836 34.8 239.5 41.1 305.1
AUSTIN AU930 30.4 262.3 40.6 332.1
*WAKKANAI WK546 45.4 141.7 39.6 214.2
*ROME RO041 41.9 12.5 36.9 87.4
ROME RA041 41.8 12.5 36.8 87.4
SAN_VITO VT139 40.6 17.8 35.6 92.1
BEIJING BP440 40.0 116.3 35.2 190.1
ROQUETES EB040 40.4 0.5 35.0 76.7
ASHKHABAD AS237 37.9 58.3 34.2 131.4
ATHENS AT138 38.0 23.6 32.8 97.3
GIBILMANNA GM037 37.9 14.0 32.2 88.5
I-CHEON IC437 37.1 127.5 31.6 200.9
NICOSIA NI135 35.0 33.2 30.1 106.3
KOKUBUNJI TO536 35.7 139.5 29.6 212.2
JEJU JJ433 33.4 126.3 27.8 199.6
PUERTO_RICO PRJ18 18.1 293.9 26.9 11.6
YAMAGAWA YG431 31.2 130.6 25.2 203.7
CHONGQING 09429 29.5 106.4 24.3 179.6
LUALUALEI LL721 21.4 201.9 21.6 270.8
OKINAWA OK426 26.3 127.8 20.2 200.7
GUANGZHOU GU421 23.1 113.4 17.3 186.3
HAINAN HA419 18.3 109.3 12.1 182.1
GUAM GU513 13.6 144.9 6.4 216.9
BELEM BLJ03 -1.4 311.6 -0.0 24.4
JICAMARCA JI91J -12.0 283.2 -0.2 355.9
SAO_LUIS SAA0K -2.6 315.8 -3.4 27.7
FORTALEZA FZA0M -3.9 321.6 -7.6 32.5
TUCUMAN TUJ2O -26.9 294.6 -16.3 5.0
ASCENSION AS00Q -7.9 345.6 -19.0 56.4
CACHOEIRA_PAULISTA CAJ2M -23.2 314.2 -20.0 20.9
NIUE ND61R -19.1 190.1 -21.8 266.6
DARWIN DW41K -12.4 130.9 -21.8 204.0
COCOS CS31K -12.2 96.8 -22.4 168.8
BAHIA_BLANCA BBJ3R -38.7 297.7 -27.9 7.0
TOWNSVILLE TV51R -19.3 146.7 -28.6 221.5
*LEARMONTH LM42B -21.8 114.1 -32.8 186.6
LEARMONTH LM42J -22.2 114.1 -33.2 186.5
NORFOLK_IS NI63_ -29.0 168.0 -36.3 246.7
BRISBANE BR52P -27.1 153.1 -36.5 229.8
GRAHAMSTOWN GR13L -33.3 26.5 -42.3 92.5
HERMANUS HE13N -34.4 19.2 -43.0 84.7
CAMDEN CN53L -34.0 150.7 -44.2 228.7
PERTH PE43K -32.0 116.1 -44.3 188.2
CANBERRA CB53N -35.3 149.0 -45.8 227.1
*HOBART HO54K -42.9 147.3 -54.3 227.3
*MAWSON MW26P -67.6 62.9 -71.3 93.0
*JANG_BOGO JB57N -74.6 164.2 -80.1 305.3
*SCOTT_BASE SQ67Q -77.8 166.8 -80.2 324.9
*CASEY CW46O -66.3 110.5 -80.7 161.3

[NOTE: Stations marked with an * were not included in the SSNe calculation either because they are above the high-latitude cutoff
(poleward of 50deg geomagnetic latitude) or because they were excluded for data quality reasons.]


AKNOWLEDGEMENT:
The fof2 data used in these plots came from the NOAA Centers for Environmental Information.

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