## 5 Results
### Historical Series  
#### 5.1.1 Magnetic Field  
The 17 years of operation of the LIV geomagnetic observatory has yielded a valuable data series, with accurate datasets during the attended (summer) season, complying with all of the IAGA standards [17], and even most of the more restrictive INTERMAGNET standards [35] as far as accuracy, sampling rate, and data processing requirements are concerned. The winter seasons have been, however, more controversial. Interruptions due to power loss from the base, or incidences in the observatory hardware and software have sometimes left the station partially or totally disabled for several months in a row. However, these relatively few gaps have not avoided a characterization of the largest peak amplitudes, which reached a drop of around 1300 nT in the magnetic field strength during  
Figure 9: Frame organization of the physical layer. T\({}_{\text{train}}\) is the period of the training sequence. The frame period T\({}_{\text{f}}\) is designed to be clearly lower than the coherence time of the channel T\({}_{\text{coh}}\). the main phase of a severe magnetic storm [36], or the behavior of the quiet-day variations [2]. As for the extreme expected values, unfortunately the Halloween storm (29-31 October 2003), one of the major space weather historical events, coincided with one of those unattended periods in which we lost data (in that occasion it was due to the breakage of the wind generators that, along with some solar panels, were supplying power during the winter), thus, although rare, even more extreme scenarios than the above mentioned are possible. As for the regular daily variation, the largest amplitudes occur, as expected, during the summer and the smallest in winter, with the typical patterns in each component for a station located south of the southern hemisphere current focus but still away from the auroral region. A clear dependence of the _Sq_ amplitude on solar activity was also found. Other results from LIV data concern instrumental aspects, which, although strictly speaking are only valid for the instruments operating at LIV, other observatories with similar equipment can benefit from. On one hand, a summarized description of the principles and operation of the \(\delta D/\delta I\) variometer was given in [37], while an assessment of their accuracy and time resolution given the assumed approximations, together with a critical examination of their potential sources of error, can be found in [38]. Further on, once the observatory instrumentation was upgraded with the addition of the triaxial fluxgate magnetometer and new sampling hardware and data logging software (as described in [36]), simultaneous data comparisons with the old \(\delta D/\delta I\) variometer helped to assess the temperature sensitivity of both [39, 40]. It has been revealed that both instruments are sensitive to temperature variations, but in a dynamic way, and with a different response for each magnetic element. In general, results show a somewhat higher temperature sensitivity of the large size \(\delta D/\delta I\) coils than that of the fluxgate variometer. On the other hand, an assessment of the performance of the D/I-flux instrument in use at LIV, and an analysis of the sources of uncertainty that in general this kind of instruments present can be found in [41]. This latter article reveals that, although the D/I-flux has become the international standard to undertake absolute measurements of the angular elements in every geomagnetic observatory, its accuracy is limited by a series of effects, and a list of recommendations for the reduction of errors is given as well. For what concerns data processing aspects, LIV data (among others) have been used in [42] to investigate the impact of fundamental minute-data loss in the computation of the observatory hourly mean values of the geomagnetic field, where limits in the number of missing data are recommended to produce representative values.