Schmucker-Weidelt Lecture Notes, Aarhus, 1975 - MTNet
Schmucker-Weidelt Lecture Notes, Aarhus, 1975 - MTNet Schmucker-Weidelt Lecture Notes, Aarhus, 1975 - MTNet
with 4 as geographic latitude. From the %Q : FISQ ratio of continental stations a depth of penetration between 300 and 500 km is inferred. The penetration depth of SQ in the -ocean basins is still uncertah. Bays and - Polar Substorms: During the night hours "bay-shaped" de- flections of the Earth's magnetic fi.eld from the normal level ave observed from time to time, lasting about one hour. Their amplitude increases steadily from south to north, reachi-ng its highest value in the auroral zone. Similar variafions, but much more intense and rapid, occur during the main phase of magnetic storms, until about one day after stormbegin. The source of these so-call-ed "polar substorms" is a shifting and oscillating current lineament i.n the ionosphere of the aurora zone. The current wil].be partly cl-osed th~ough field alligned currents in the magnetosphere, partly by wide-spread ionospheric return currents in mid latitudes: S,'L
polar substorlns is j.n mid-latitudes (e.g. Denmarlc, Germany) much smaller than the ampliiudes of H and D - because the vertical field of induction currents nearly cancels the vertical field of the polar jet. Under "normal condirtions" the Z:I-l ratio is about 1: '10. Assu~ning for the mid--latitude substorm field an effective wave number of 10- 20 000 km, yielding kx 3-6*10-~ as wavenumber, depth of penetration i.s 'bay A I = 150 to 300 km. bay kx There are indications tllat the penetration deptll of bays into -the oceanic substructure is substantialiy smaller. The ocean itself produces an attenuation of the H-ar~pl.itude of about 75% at the ocean bottcm, deep basins filled with unconsolidated sediments can yield a comparable attenua-tion &-6. North German basin). Pulsations and VLF-emissions: Rapid oscilla-tions of the Earth's fie1 - - with periods between 5 minu-tes and 1 second are called pu1.sati.011~. Their ampli-tude increases 1.iIce the ainpli-tude of substorms strongly when approaching the auroral zone. Their typical midlati.tude ampli-tude is 1 gamma. The source field structure of bays and pul.- sstions is similar, the depth of pene-tra-t:ion of pulsations being largely dependent on the near-surfack conductivity. Lt may rmge from many kilometers in exposed shield areas to a few hundred meters and less in sedimentary basins. The "normal" Z:H ra-tio o:E pulsations is too small to be determS.~-rccl with any reliabili-ty outside of the auroral zone. However, "an~!naI.oi Z-pulsations. are frequent and usually of very local. charak-ter. IF pulsations occur in the form of las-tine harmonic oscilla-:ions , oftel with a beat-frequency, they are called "pulsation tr>ains1' pt, sin~J.( pul-satj.on events are ' called "pi" , pul.satj.ons which rt~arlc the be- ginning of a bay.dis-turbance are called "pc". All three types !la\'c a clear local time dependence, occuring almost daily: 'F\ 1-1 m- -7,. -
- Page 49 and 50: From the generalized Green's theore
- Page 51 and 52: and y can again be so adjusted that
- Page 53 and 54: 4.2. In3ral - --- equation method L
- Page 55 and 56: The element GZx is needed for all z
- Page 57 and 58: With this knowledge of the behaviou
- Page 59 and 60: After having determined Qzr VJ,; @,
- Page 61 and 62: 4.3. The surface inteyral approach
- Page 63 and 64: F At the vertical boundaries the co
- Page 65 and 66: The four equations A A A A H = i sg
- Page 68 and 69: 6. Approaches to the inverse proble
- Page 70 and 71: to minimize the quantity a s = 12 /
- Page 72 and 73: It remains to show a way to minimiz
- Page 74 and 75: Agai-n, from a finite erroneous dat
- Page 76 and 77: Here lJ - is a N x P matrix contain
- Page 78 and 79: small eigenvalues. The parameter ve
- Page 80 and 81: Then - 77 - A(E2 - E ) = iwu U (E -
- Page 82 and 83: whence 2k d -2k d where a = CA:(A;)
- Page 84 and 85: . 7. Basic concepts of geomagnetic
- Page 86 and 87: orders of magnitude smaller' than t
- Page 88 and 89: Elimination of - E or .,. H yields
- Page 90 and 91: Observing that rot pot rot g = - ro
- Page 92 and 93: Two special types of such anomalies
- Page 94 and 95: Model : wo+ Solution for uniform ha
- Page 96 and 97: parameter u and that the pressure d
- Page 98 and 99: (=disturbed)-variations: After magn
- Page 102 and 103: Very rapid oscillations with freque
- Page 104 and 105: ! 8. Data Collection - and Analysis
- Page 106 and 107: A horizontal electric -- field comp
- Page 108 and 109: For a data reducti.on in the fr3equ
- Page 110 and 111: Let q be the tranfer function betwe
- Page 112 and 113: . A as transfer function between A
- Page 114 and 115: -- Structural soundi~z with station
- Page 116 and 117: Since it follows that - E 1 = - T E
- Page 118 and 119: - - . the same or from different si
- Page 120 and 121: The Fourier integral - +- -io t T -
- Page 122 and 123: The weigh-t . function W is then fo
- Page 124 and 125: Two convenient filters are 3 sinx I
- Page 126 and 127: (e.g. X), their realizations by obs
- Page 128 and 129: Observe that the residual, of which
- Page 130 and 131: Example: n = 12 and @ = 95%: 1 n =
- Page 132 and 133: - As a consequence, the real and im
- Page 134 and 135: This relati-on implies .that .the l
- Page 136 and 137: 9. --- Data 5.nterpretatj.on on the
- Page 138 and 139: The "modified apparent - - resistiv
- Page 140 and 141: Exercise Geomagne-tic varj.ations.
- Page 142 and 143: 9.2 Layered Sphere - The sphericity
- Page 144 and 145: The field within the conducting sph
- Page 146 and 147: and An algorithm for the direct pro
- Page 148 and 149: with I - and- a = gn g-n I 1 6-n-1
with 4 as geographic latitude. From the %Q : FISQ ratio of continental<br />
stations a depth of penetration between 300 and 500 km is inferred.<br />
The penetration depth of SQ in the -ocean basins is still uncertah.<br />
Bays and - Polar Substorms: During the night hours "bay-shaped" de-<br />
flections of the Earth's magnetic fi.eld from the normal level ave<br />
observed from time to time, lasting about one hour. Their amplitude<br />
increases steadily from south to north, reachi-ng its highest value<br />
in the auroral zone. Similar variafions, but much more intense and<br />
rapid, occur during the main phase of magnetic storms, until about<br />
one day after stormbegin.<br />
The source of these so-call-ed "polar substorms" is a shifting and<br />
oscillating current lineament i.n the ionosphere of the aurora zone.<br />
The current wil].be partly cl-osed th~ough field alligned currents<br />
in the magnetosphere, partly by wide-spread ionospheric return<br />
currents in mid latitudes:<br />
S,'L
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