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The Earth's magnetic field is described by seven parameters.To measure the Earth's magnetism in any place, we must measure the direction and intensity of the field. The parameters describing the direction of the magnetic field are declination (D), inclination (I). D and I are measured in units of degrees. The intensity of the total field (F) is described by the horizontal component (H), vertical component (Z), and the north (X) and east (Y) components of the horizontal intensity. These components may be measured in units of Oersted (1 oersted=1gauss) but are generally reported in nanoTesla (1nT * 100,000 = 1 0ersted). The Earth's magnetic field intensity is roughly between 25,000 - 65,000 nT (.25 - .65 oersted). Magnetic declination is the angle between magnetic north and true north. D is considered positive when the angle measured is east of true north and negative when west. Magnetic inclination is the angle between the horizontal plane and the total field vector. The geomagnetic field measured at any point on the Earth's surface is a combination of several magnetic fields generated by various sources. These fields are superimposed on and interact with each other. More than 90% of the field measured is generated INTERNAL to the planet in the Earth's outer core. This portion of the geomagnetic field is often refered to as the Main Field. The Main Field varies slowly in time and can be described by Mathematical Models such as the International Geomagnetic Reference Field (IGRF) and World Magnetic Model (WMM). The Main Field creates a cavity in interplanetary space called the magnetosphere, where the Earth's magnetic field dominates in the magnetic field of the solar wind. The magnetosphere is shaped somewhat like a comet in response to the dynamic pressure of the solar wind. It is compressed on the side toward the sun to about 10 Earth radii and is extended tail-like on the side away from the sun to more than 100 Earth radii. The magnetosphere deflects the flow of most solar wind particles around the Earth, while the geomagnetic field lines guide charged particle motion within the magnetosphere. The differential flow of ions and electrons inside the magnetosphere and in the ionosphere form current systems, which cause variations in the intensity of the Earth's magnetic field. These EXTERNAL currents in the ionized upper atmosphere and magnetosphere vary on a much shorter time scale than the INTERNAL Main Field and may create magnetic fields as large as 10% of the Main Field. Other important sources are the fields arising from electrical currents flowing in the ionized upper atmosphere, and the fields induced by currents flowing within the Earth's crust. The Main field component varies slowly in time and can be grossly described as that of a bar magnet with north and south poles deep inside the Earth and magnetic field lines that extend well out into space. The Earth's magnetic field varies both in space and time. Historically, magnetic observatories were established to monitor the secular change of the Earth's magnetic field, and this remains one of their most important functions. This generally involves absolute measurements sufficient in number to monitor instrumental drift and to produce annual means. Over 70 countries operate more than 200 observatories worldwide. The magnetic observatory mean data are crucial to the studies of secular change, investigations into the Earth's interior, and to global modeling efforts
Geomagnetic indices constitute data series aiming at describing at a planetary scale the magnetic activity, or some of its components. The data series are homogeneous since 1932 for Kp and Ap, 1957 for Dst.
K indices isolate solar particle effects on the earth's magnetic field; over a 3-hour period, they classify into disturbance levels the range of variation of the more unsettled horizontal field component. Each activity level relates almost logarithmical- ly to its corresponding disturbance amplitude. Three-hour indices discriminate conservatively between true magnetic field perturbations and the quiet-day variations produced by ionospheric currents. K indices range in 28 steps from 0 (quiet) to 9 (greatly disturbed) with fractional parts expressed in thirds of a unit. A K-value equal to 27, for example, means 2 and 2/3 or 3-; a K-value equal to 30 means 3 and 0/3 or 3 exactly; and a K-value equal to 33 means 3 and 1/3 or 3+. The arithmetic mean of the K values scaled at the 13 specific observatories gives Kp: ( Lerwick (UK), Eskdalemuir (UK), Hartland (UK), Ottawa (Canada), Fredericksburg (USA) , Meannook (Canada), Sitka (USA), Eyrewell (New Zealand), Canberra (Aus- tralia), Lovo (Sweden), Brorfelde (Denmark), Wingst (Germany), and Niemegk (Germany).) .
: a 3-hourly "equivalent amplitude" index of local geomagnetic activity; "a" is related to the 3-hourly K INDEX according to the following scale:
K = 0 1 2 3 4 5 6 7 8 9
a = 0 3 7 15 27 48 80 140 240 400
A Index
: A daily index of geomagnetic activity derived as the average of the eight 3-hourly a indices.
Ap Index
: An averaged planetary ApIndex based on data from a set of specific Kp stations.
DST (Disturbance Storm Time)
Dst (Disturbance Storm Time) equivalent equatorial magnetic disturbance indices are derived from hourly scalings of low-latitude horizontal magnetic variation. They show the effect of the globally symmetrical westward flowing high altitude equatorial ring current, which causes the "main phase" depression worldwide in the H-component field during large magnetic storms. Unit - nT.
Cp or Planetary Daily Character Figure
A qualitative estimate of overall level of magnetic activity for the day determined from the sum of the eight Ap amplitudes. Cp ranges, in steps of one-tenth, from 0 (quiet) to 2.5 (highly disturbed).
C9
A conversion of the 0-to-2.5 range of the Cp index to one digit between 0 and 9
1.1 Online Data as separate file:
AA 1868 - Present (3 hourly and daily)(monthly)(yearly)(Lists and histograms of geomagnetic disturbance and Solar Sunspots) KP_AP 1932 - Present (3 hourly and daily) (Lists and histograms of geomagnetic disturbance and Solar Sunspots) AE_HV 1957-75, 78-88 (hourly) AE_MIN 1978-881-6;198903;1990-94 (minute) DST 1957 - Present (hourly) PC 1975 - Present (15-minute) AMANAS 1959 - Present (3 hourly and daily) KMKNKS 1983 - Present (3 hourly)
1.2 Online Data in interactive forms in SPIDR
Online Data in interactive forms in new interactive system "Space Physics
Ineractive Data Resource" - "SPIDR"
Indices: Ap, Kp, Cp, C9, Dst ln SPIDR
1.3 Data in other forms
Tables of different geomagnetic indices.
Publications of WDCs.
Sudden Commencement 1868 - present
3. Minute Values of Geomagnetic Field Components
This Directory contains Minute values of geomagnetic field components at observatories in Russia and other republic of Former Soviet Union (FSU). Data are prepared in the form of monthly files.
Online Data in interactive forms in new interactive system "Space Physics
Ineractive Data Resource" - "SPIDR"
1.Minute values of geomagnetic field
elements for World network geomagnetic stations (453 st)
in SPIDR
4. Hourly Values of Geomagnetic Field Components
1. This Directory contains mean hour values of geomagnetic field components at observatories in Russia and other repub- lic of Former Soviet Union (FSU). The List of these observatories has indication of Data Years. Data are prepared in the form of yearly files. For example, File "aaa64hv" contains Data of the Alma Ata Obsevatory for the complete 1964 of D, H and Z components. File "tkt90_6z contains Z-component Data for 06 month 1990. File "ars73hv_" contains Data for a complete year minus a few days. Files are prepared in the DOS format. 2. The Format for mean values follows after this list of the geomagnetic observatories. 3. Program "aaa1_bas.exe" allow to select Data from the yearly files in the DOS format.
List of geomagnetic observatories.
================================================================ OBSERVATORIES CODE CO LAT. LON. DATA YEARS ================================================================ ALMA ATA AAA FSU-Kaz. 43.25 76.92 63 - 72,75-82,84-90 ARKHANGELSK ARK FSU-Rus. 64.60 40.50 82 - 89 ASHKHABAD ASH FSU-Tur. 37.95 58.11 59 - 70,72-85 BOROK BOX FSU-Rus. 58.03 38.97 80 - 91 CAPE CHELYUSKIN CCS FSU-Rus. 77.72 104.28 57 - 85 CAPE WELLEN CWE FSU-Rus. 66.16 190.17 57 - 87 DIXON ISLAND DIK FSU-Rus. 73.54 80.56 57 - 86 HEISS ISLAND HIS FSU-Rus. 80.62 58.05 58 - 69 IRKUTSK IRT FSU-Rus. 52.46 104.04 57 - 90 KARAGANDA KGD FSU-Kaz. 49.82 73.08 65 - 76, 80, 84-89 KAZAN KZN FSU-Rus. 55.83 48.85 64 - 74, 78 - 89 KIEV KIV FSU-Ukr. 50.72 30.30 58 - 91 LENINGRAD LNN FSU-Rus. 59.95 30.71 48 - 88 LVOV LVV FSU-Ukr. 49.90 23.75 57 - 72,78 MAGADAN MGD FSU-Rus. 60.12 151.02 66 - 89 MINSK MNK FSU-Rus. 54.50 27.88 61 - 89 MIRNY MIR AY -66.55 93.02 56 - 85 MOLODEZHNAYA MOL AY -67.67 45.85 65 - 77 MOSCOW MOS FSU-Rus. 55.48 37.31 58 - 89 MURMANSK MMK FSU-Rus. 68.95 33.05 59 - 80 NOVOKAZALINSK NKK FSU-Kaz. 45.80 62.10 80 NOVOLAZAREVSKAYA NVL AY -70.77 11.83 61 - 78 NOVOSIBIRSK NVS FSU-Rus. 55.03 82.90 67 - 91,94,95 OASIS OAS AY -66.30 100.72 57 - 58 ODESSA ODE FSU-Ukr. 46.78 30.88 57 - 91 P. TUNGUSKA POD FSU-Rus. 61.60 90.00 69 - 91 PETROPAVLOVSK PET FSU-Rus. 52.90 158.43 69 - 90 PIONERSKAYA PIO AY -69.73 95.50 57,58,71,72 SVERDLOVSK(V.DUB)SVD FSU-Rus. 56.73 61.07 45-52,54,56-74,79,80 SVERDLOVSK(ARTI) ARS FSU-Rus. 56.43 58.57 73 - 88 TASHKENT TKT FSU-Uzb. 41.33 69.62 57 - 71,80,84-91 TBILISI TFS FSU-Geo. 42.09 44.71 59 - 90 TIKHAYA BAY TKH FSU-Rus. 80.33 52,80 57 TIXIE BAY TIK FSU-Rus. 71.58 129.00 57 - 86 VLADIVOSTOK VLA FSU-Rus. 43.78 132.03 57 - 89 VOSTOK VOS AY -78.45 106.87 58 - 61,63-85 YAKUTSK YAK FSU-Rus. 62.02 129.72 57 - 89 YUZHNO SAKHALINS YSS FSU-Rus. 46.95 142.72 57 - 88 ==========================================================
=============================================================== 1-3 A3 OBSERVATORY 3-LETTER CODE 4-5 I2 YEAR (last 2 digits, 82=1982) 6-7 I2 MONTH (01-12) 8 I1 ELEMENT (D, H, F, X, Y, or Z) 9-10 I2 DAY OF MONTH (01-31) 11-12 I2 Blanks for hourly values. Values of hourly (00-23) for 2.5 minute values. 13-15 A3 Arbitrary 16 I1 Blank for data since 1900, 8 for data before. 17-20 I4 Tabular base, in degrees for D and I, hundreds of nanoTeslas (gammas) for the intensity elements. 21-116 24I4 24 Twenty-four 4-digit Hourly Values for the day. Values are in tenth-minutes for D and nanoTeslas (gammas)for the intensity elements. Or twenty-four 4-digit 2.5 minute values in the hour. A missing value is identified by 9999. 117-120 I4 Daily Mean or Hourly for the 2.5 minute data. =================================================================
Online Data in interactive forms in new interactive system "Space Physics
Ineractive Data Resource" - "SPIDR"
1.Mean hourly values of geomagnetic
field elements for World network geomagnetic stations (453 st) in SPIDR
Tables of hourly values geomagnetic field elements.
Publications of WDCs.
5. Daily Values of Geomagnetic Field Component
This Directory contains mean daily values of geomagnetic
field components at the Tbilisi Observatory (1880 - 1991).
This Directory
was prepared by Institute of Geophysics of Georgian Academy of Science.
Catalogue of geomagnetic pulsations of Pc1 at observatory BOROK (1957 - 1992).
Microfilms and microfiches of Analog magnetograms from 1957
for World
network of geomagnetic stations.
This directiry contains catalogue of magnetograms in WDC for STP, Moscow