http://earthwise.bgs.ac.uk/index.php?action=history&feed=atom&title=OR%2F14%2F004_Worst_case_scenario_research_at_BGSOR/14/004 Worst case scenario research at BGS - Revision history2026-06-28T20:14:32ZRevision history for this page on the wikiMediaWiki 1.42.3http://earthwise.bgs.ac.uk/index.php?title=OR/14/004_Worst_case_scenario_research_at_BGS&diff=43703&oldid=prevDbk: /* Extreme GIC in the UK grid */2019-11-28T08:40:40Z<p><span dir="auto"><span class="autocomment">Extreme GIC in the UK grid</span></span></p>
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<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 09:40, 28 November 2019</td>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Using the EVS results of Thomson et al. (2011)<ref name="Thomson 2011"></ref>, summarised in Section 2.1, Beggan et al. (2013)<ref name="Beggan 2013">BEGGAN, C D, BEAMISH, D, RICHARDS, A, KELLY, G S, and THOMSON, A W P. 2013. Prediction of extreme geomagnetically induced currents in the UK high-voltage network, SpaceWeather, 11, doi:10.1002/swe.20065. </ref> investigated the impact of extreme geomagnetic variations in terms of worst case GIC in the UK transmission system. Beggan et al. firstly created an updated model of the UK surface conductivity by combining a spatial database of the UK geological properties (i.e., rock type) with an estimate of the conductivity for specific formations. Secondly, they developed and implemented a sophisticated and up-to-date model for the 400 kV and 275 kV electrical networks across the whole of Great Britain and, in addition, for the 132 kV network in Scotland.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Using the EVS results of Thomson et al. (2011)<ref name="Thomson 2011"></ref>, summarised in Section 2.1, Beggan et al. (2013)<ref name="Beggan 2013">BEGGAN, C D, BEAMISH, D, RICHARDS, A, KELLY, G S, and THOMSON, A W P. 2013. Prediction of extreme geomagnetically induced currents in the UK high-voltage network, SpaceWeather, 11, doi:10.1002/swe.20065. </ref> investigated the impact of extreme geomagnetic variations in terms of worst case GIC in the UK transmission system. Beggan et al. firstly created an updated model of the UK surface conductivity by combining a spatial database of the UK geological properties (i.e., rock type) with an estimate of the conductivity for specific formations. Secondly, they developed and implemented a sophisticated and up-to-date model for the 400 kV and 275 kV electrical networks across the whole of Great Britain and, in addition, for the 132 kV network in Scotland.</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>They were then able to deduce the expected GIC at each transformer node in the system based on the network topology and an input ‘extreme’ surface electric field. Beggan et al. applied these developments to study the theoretical response of the present-day UK high-voltage power grid to modeled extreme 100 year and 200 year space weather scenarios and to a scaled version of the October 2003 geomagnetic storm, approximating a 1 in 200 year event. The analysis of Beggan et al derived much from Thomson et al. (2005)<ref name="Thomson 2005"><del style="font-weight: bold; text-decoration: none;">THOMSON, A W P, McKAY, A J, CLARKE, E, and REAY, S J. 2005. Surface electric fields and Geomagnetically Induced Currents in the Scottish Power grid during the 30 October 2003 geomagnetic storm, Space Weather, 3, S11002, doi:10.1029/2005SW000156.</del></ref>, Beamish et al. (2002)<ref name="Beamish 2002">BEAMISH, D, CLARK, T D G, CLARKE, E, and THOMSON, A W P. 2002. Geomagnetically induced currents in the UK: Geomagnetic variations and surface electric fields, J. Atmos. Sol. Terr. Phys., 64, 1779–1792, doi:10.1016/S1364- 6826(02)00127-X.</ref> and McKay (2003)<ref name="McKay 2003">McKAY, A. 2003. Geoelectric fields and Geomagnetically Induced Currents in the United Kingdom, PhD thesis, Univ. of Edinburgh, Edinburgh, UK. </ref>.</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>They were then able to deduce the expected GIC at each transformer node in the system based on the network topology and an input ‘extreme’ surface electric field. Beggan et al. applied these developments to study the theoretical response of the present-day UK high-voltage power grid to modeled extreme 100 year and 200 year space weather scenarios and to a scaled version of the October 2003 geomagnetic storm, approximating a 1 in 200 year event. The analysis of Beggan et al derived much from Thomson et al. (2005)<ref name="Thomson 2005"></ref>, Beamish et al. (2002)<ref name="Beamish 2002">BEAMISH, D, CLARK, T D G, CLARKE, E, and THOMSON, A W P. 2002. Geomagnetically induced currents in the UK: Geomagnetic variations and surface electric fields, J. Atmos. Sol. Terr. Phys., 64, 1779–1792, doi:10.1016/S1364- 6826(02)00127-X.</ref> and McKay (2003)<ref name="McKay 2003">McKAY, A. 2003. Geoelectric fields and Geomagnetically Induced Currents in the United Kingdom, PhD thesis, Univ. of Edinburgh, Edinburgh, UK. </ref>.</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>As a first hypothetical model, Beggan et al. developed two synthetic electrojet model profiles: an electrojet model with an amplitude profile akin to a ‘top-hat’ function, extending from 53N to 63N in geomagnetic latitude, with a second model that had a ‘tapered cosine’ profile extending between 48N and 68N in geomagnetic latitude. They used the two different models to examine if the amplitude gradient (slope) of the magnetic field strongly affects the estimated GIC. The Top-Hat model gave a very strong gradient across its edges while the Tapered-Cosine model had a gentler gradient. Two orientations of the auroral electrojet were computed for each synthetic 100 and 200 year electrojet: (a) geomagnetically east-west aligned across the UK and (b) a geomagnetic north-south alignment (approximately following the central axis of the UK).</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>As a first hypothetical model, Beggan et al. developed two synthetic electrojet model profiles: an electrojet model with an amplitude profile akin to a ‘top-hat’ function, extending from 53N to 63N in geomagnetic latitude, with a second model that had a ‘tapered cosine’ profile extending between 48N and 68N in geomagnetic latitude. They used the two different models to examine if the amplitude gradient (slope) of the magnetic field strongly affects the estimated GIC. The Top-Hat model gave a very strong gradient across its edges while the Tapered-Cosine model had a gentler gradient. Two orientations of the auroral electrojet were computed for each synthetic 100 and 200 year electrojet: (a) geomagnetically east-west aligned across the UK and (b) a geomagnetic north-south alignment (approximately following the central axis of the UK).</div></td></tr>
</table>Dbkhttp://earthwise.bgs.ac.uk/index.php?title=OR/14/004_Worst_case_scenario_research_at_BGS&diff=43702&oldid=prevDbk: /* EVS and Nagycenk geoelectric observatory data */2019-11-28T08:39:16Z<p><span dir="auto"><span class="autocomment">EVS and Nagycenk geoelectric observatory data</span></span></p>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>In 2012, geoelectric monitoring sites were installed at each of the three UK geomagnetic observatories. Data are now being recorded at these sites with the intention, over the long term, of comparing with the Nagycenk data, to provide a wider European scale view of surface geoelectric fields.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>In 2012, geoelectric monitoring sites were installed at each of the three UK geomagnetic observatories. Data are now being recorded at these sites with the intention, over the long term, of comparing with the Nagycenk data, to provide a wider European scale view of surface geoelectric fields.</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>For an initial look, in Figure 2.12 we show the distribution of electric field values from the Eskdalemuir observatory, for 1st January to 1st August 2013. It can be seen that there is a long tail in the distribution, in both the north (''E''x) and east (''E''y) components. Moreover there are clear difference between the Ex and Ey channels. This may be physical (local effects?) or may reflect issues with the instrumentation. We note that the local maxima during this time interval (of ~0.2V/km) compare with an estimated 5V/km for central Scotland during the October 2003 storm (Thomson et al., 2005<ref name="Thomson 2005">THOMSON, A W P, McKAY, A J, CLARKE, E, and REAY, S J. 2005). Surface electric fields and Geomagnetically Induced Currents in the Scottish Power grid during the 30 October 2003 geomagnetic storm, Space Weather, 3, S11002, doi:10.1029/2005SW000156.</ref>) and even estimates of ~20V/km for genuinely extreme events in resistive geological terranes (e.g. Pulkkinen et al., 2012<ref name="Pulkkinen 2012"><del style="font-weight: bold; text-decoration: none;">PULKKINEN, A, BERNEBEU, E, EICHNER, J, BEGGAN, C and THOMSON, A W P. 2012). Generation of 100-year geomagnetically induced current scenarios, Space Weather, 10, S04003, doi:10.1029/2011SW000750.</del></ref>).</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>For an initial look, in Figure 2.12 we show the distribution of electric field values from the Eskdalemuir observatory, for 1st January to 1st August 2013. It can be seen that there is a long tail in the distribution, in both the north (''E''x) and east (''E''y) components. Moreover there are clear difference between the Ex and Ey channels. This may be physical (local effects?) or may reflect issues with the instrumentation. We note that the local maxima during this time interval (of ~0.2V/km) compare with an estimated 5V/km for central Scotland during the October 2003 storm (Thomson et al., 2005<ref name="Thomson 2005">THOMSON, A W P, McKAY, A J, CLARKE, E, and REAY, S J. 2005). Surface electric fields and Geomagnetically Induced Currents in the Scottish Power grid during the 30 October 2003 geomagnetic storm, Space Weather, 3, S11002, doi:10.1029/2005SW000156.</ref>) and even estimates of ~20V/km for genuinely extreme events in resistive geological terranes (e.g. Pulkkinen et al., 2012<ref name="Pulkkinen 2012"></ref>).</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Over time, probably many years, we hope to construct a data set from which we can analyse the tail of the UK distributions using EVS, with a view to confirming, or otherwise, estimated extremes in modeled electric fields, such as given by Pulkkinen et al. (2012)<ref name="Pulkkinen 2012"></ref>, or the results obtained from Nagycenk.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Over time, probably many years, we hope to construct a data set from which we can analyse the tail of the UK distributions using EVS, with a view to confirming, or otherwise, estimated extremes in modeled electric fields, such as given by Pulkkinen et al. (2012)<ref name="Pulkkinen 2012"></ref>, or the results obtained from Nagycenk.</div></td></tr>
</table>Dbkhttp://earthwise.bgs.ac.uk/index.php?title=OR/14/004_Worst_case_scenario_research_at_BGS&diff=43701&oldid=prevDbk: Undo revision 43700 by Dbk (talk)2019-11-28T08:38:37Z<p>Undo revision 43700 by <a href="/index.php/Special:Contributions/Dbk" title="Special:Contributions/Dbk">Dbk</a> (<a href="/index.php/User_talk:Dbk" title="User talk:Dbk">talk</a>)</p>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>The comparison with the earlier paper is made between the rows labelled ‘minute’ (the new results) and ‘2011 paper’ (published results). Given the wide 95% confidence limits in the earlier work these new results are broadly consistent, which provides confidence in the statistical robustness of our approach. Interestingly comparison with the daily block maximum results (‘daily max’ row) shows some large differences particularly in d''H''/dt and d''X''/dt. This will be investigated further.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>The comparison with the earlier paper is made between the rows labelled ‘minute’ (the new results) and ‘2011 paper’ (published results). Given the wide 95% confidence limits in the earlier work these new results are broadly consistent, which provides confidence in the statistical robustness of our approach. Interestingly comparison with the daily block maximum results (‘daily max’ row) shows some large differences particularly in d''H''/dt and d''X''/dt. This will be investigated further.</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>Eight observatories have been assessed so far and provisional results are shown in Figure 2.7 for the d''H''/dt component. Even allowing for the relative lack of data (yet) from the southern hemisphere we see a degree of hemispheric symmetry, e.g. as reported by Pulkkinen et al. (2012)<ref name="Pulkkinen 2012"></ref> and Ngwira et al (2013a)<ref name="Ngwira 2013a">NGWIRA, C M, PULKKINEN, A, WILDER, F D, and CROWLEY, G. 2013a. Extended study of extreme geoelectric field event scenarios for geomagnetically induced current applications, Space Weather, 11, 121–131, doi:10.1002/swe.20021.</ref>, as well as the ‘auroral bulge’ of Thomson et al. (2011)<ref name="Thomson 2011"></ref>.</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>Eight observatories have been assessed so far and provisional results are shown in Figure 2.7 for the d''H''/dt component. Even allowing for the relative lack of data (yet) from the southern hemisphere we see a degree of hemispheric symmetry, e.g. as reported by Pulkkinen et al. (2012)<ref name="Pulkkinen 2012"><ins style="font-weight: bold; text-decoration: none;">PULKKINEN, A E, BERNEBEU, J, EICHNER, C, BEGGAN, and THOMSON, A W P. 2012. Generation of 100-year geomagnetically induced current scenarios, Space Weather, 10, S04003, doi:10.1029/2011SW000750</ins></ref> and Ngwira et al (2013a)<ref name="Ngwira 2013a">NGWIRA, C M, PULKKINEN, A, WILDER, F D, and CROWLEY, G. 2013a. Extended study of extreme geoelectric field event scenarios for geomagnetically induced current applications, Space Weather, 11, 121–131, doi:10.1002/swe.20021.</ref>, as well as the ‘auroral bulge’ of Thomson et al. (2011)<ref name="Thomson 2011"></ref>.</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[Image:OR14004fig2.7.jpg|thumb|center|500px| '''Figure 2.7'''&nbsp;&nbsp;&nbsp;&nbsp;d''H''/dt 100 and 200 year return levels using the minute max values, a threshold of 99.97% and a de-clustering run length of 12 hours (plotted by geomagnetic latitude). ]]</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[Image:OR14004fig2.7.jpg|thumb|center|500px| '''Figure 2.7'''&nbsp;&nbsp;&nbsp;&nbsp;d''H''/dt 100 and 200 year return levels using the minute max values, a threshold of 99.97% and a de-clustering run length of 12 hours (plotted by geomagnetic latitude). ]]</div></td></tr>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>In 2012, geoelectric monitoring sites were installed at each of the three UK geomagnetic observatories. Data are now being recorded at these sites with the intention, over the long term, of comparing with the Nagycenk data, to provide a wider European scale view of surface geoelectric fields.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>In 2012, geoelectric monitoring sites were installed at each of the three UK geomagnetic observatories. Data are now being recorded at these sites with the intention, over the long term, of comparing with the Nagycenk data, to provide a wider European scale view of surface geoelectric fields.</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>For an initial look, in Figure 2.12 we show the distribution of electric field values from the Eskdalemuir observatory, for 1st January to 1st August 2013. It can be seen that there is a long tail in the distribution, in both the north (''E''x) and east (''E''y) components. Moreover there are clear difference between the Ex and Ey channels. This may be physical (local effects?) or may reflect issues with the instrumentation. We note that the local maxima during this time interval (of ~0.2V/km) compare with an estimated 5V/km for central Scotland during the October 2003 storm (Thomson et al., 2005<ref name="Thomson 2005">THOMSON, A W P, McKAY, A J, CLARKE, E, and REAY, S J. 2005). Surface electric fields and Geomagnetically Induced Currents in the Scottish Power grid during the 30 October 2003 geomagnetic storm, Space Weather, 3, S11002, doi:10.1029/2005SW000156.</ref>) and even estimates of ~20V/km for genuinely extreme events in resistive geological terranes (e.g. Pulkkinen et al., 2012<ref name="Pulkkinen 2012"></ref>).</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>For an initial look, in Figure 2.12 we show the distribution of electric field values from the Eskdalemuir observatory, for 1st January to 1st August 2013. It can be seen that there is a long tail in the distribution, in both the north (''E''x) and east (''E''y) components. Moreover there are clear difference between the Ex and Ey channels. This may be physical (local effects?) or may reflect issues with the instrumentation. We note that the local maxima during this time interval (of ~0.2V/km) compare with an estimated 5V/km for central Scotland during the October 2003 storm (Thomson et al., 2005<ref name="Thomson 2005">THOMSON, A W P, McKAY, A J, CLARKE, E, and REAY, S J. 2005). Surface electric fields and Geomagnetically Induced Currents in the Scottish Power grid during the 30 October 2003 geomagnetic storm, Space Weather, 3, S11002, doi:10.1029/2005SW000156.</ref>) and even estimates of ~20V/km for genuinely extreme events in resistive geological terranes (e.g. Pulkkinen et al., 2012<ref name="Pulkkinen 2012"><ins style="font-weight: bold; text-decoration: none;">PULKKINEN, A, BERNEBEU, E, EICHNER, J, BEGGAN, C and THOMSON, A W P. 2012). Generation of 100-year geomagnetically induced current scenarios, Space Weather, 10, S04003, doi:10.1029/2011SW000750.</ins></ref>).</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Over time, probably many years, we hope to construct a data set from which we can analyse the tail of the UK distributions using EVS, with a view to confirming, or otherwise, estimated extremes in modeled electric fields, such as given by Pulkkinen et al. (2012)<ref name="Pulkkinen 2012"></ref>, or the results obtained from Nagycenk.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Over time, probably many years, we hope to construct a data set from which we can analyse the tail of the UK distributions using EVS, with a view to confirming, or otherwise, estimated extremes in modeled electric fields, such as given by Pulkkinen et al. (2012)<ref name="Pulkkinen 2012"></ref>, or the results obtained from Nagycenk.</div></td></tr>
</table>Dbkhttp://earthwise.bgs.ac.uk/index.php?title=OR/14/004_Worst_case_scenario_research_at_BGS&diff=43700&oldid=prevDbk at 08:36, 28 November 20192019-11-28T08:36:37Z<p></p>
<table style="background-color: #fff; color: #202122;" data-mw="interface">
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<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td>
<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 09:36, 28 November 2019</td>
</tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l156">Line 156:</td>
<td colspan="2" class="diff-lineno">Line 156:</td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>The comparison with the earlier paper is made between the rows labelled ‘minute’ (the new results) and ‘2011 paper’ (published results). Given the wide 95% confidence limits in the earlier work these new results are broadly consistent, which provides confidence in the statistical robustness of our approach. Interestingly comparison with the daily block maximum results (‘daily max’ row) shows some large differences particularly in d''H''/dt and d''X''/dt. This will be investigated further.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>The comparison with the earlier paper is made between the rows labelled ‘minute’ (the new results) and ‘2011 paper’ (published results). Given the wide 95% confidence limits in the earlier work these new results are broadly consistent, which provides confidence in the statistical robustness of our approach. Interestingly comparison with the daily block maximum results (‘daily max’ row) shows some large differences particularly in d''H''/dt and d''X''/dt. This will be investigated further.</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>Eight observatories have been assessed so far and provisional results are shown in Figure 2.7 for the d''H''/dt component. Even allowing for the relative lack of data (yet) from the southern hemisphere we see a degree of hemispheric symmetry, e.g. as reported by Pulkkinen et al. (2012)<ref name="Pulkkinen 2012"><del style="font-weight: bold; text-decoration: none;">PULKKINEN, A E, BERNEBEU, J, EICHNER, C, BEGGAN, and THOMSON, A W P. 2012. Generation of 100-year geomagnetically induced current scenarios, Space Weather, 10, S04003, doi:10.1029/2011SW000750</del></ref> and Ngwira et al (2013a)<ref name="Ngwira 2013a">NGWIRA, C M, PULKKINEN, A, WILDER, F D, and CROWLEY, G. 2013a. Extended study of extreme geoelectric field event scenarios for geomagnetically induced current applications, Space Weather, 11, 121–131, doi:10.1002/swe.20021.</ref>, as well as the ‘auroral bulge’ of Thomson et al. (2011)<ref name="Thomson 2011"></ref>.</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>Eight observatories have been assessed so far and provisional results are shown in Figure 2.7 for the d''H''/dt component. Even allowing for the relative lack of data (yet) from the southern hemisphere we see a degree of hemispheric symmetry, e.g. as reported by Pulkkinen et al. (2012)<ref name="Pulkkinen 2012"></ref> and Ngwira et al (2013a)<ref name="Ngwira 2013a">NGWIRA, C M, PULKKINEN, A, WILDER, F D, and CROWLEY, G. 2013a. Extended study of extreme geoelectric field event scenarios for geomagnetically induced current applications, Space Weather, 11, 121–131, doi:10.1002/swe.20021.</ref>, as well as the ‘auroral bulge’ of Thomson et al. (2011)<ref name="Thomson 2011"></ref>.</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[Image:OR14004fig2.7.jpg|thumb|center|500px| '''Figure 2.7'''&nbsp;&nbsp;&nbsp;&nbsp;d''H''/dt 100 and 200 year return levels using the minute max values, a threshold of 99.97% and a de-clustering run length of 12 hours (plotted by geomagnetic latitude). ]]</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[Image:OR14004fig2.7.jpg|thumb|center|500px| '''Figure 2.7'''&nbsp;&nbsp;&nbsp;&nbsp;d''H''/dt 100 and 200 year return levels using the minute max values, a threshold of 99.97% and a de-clustering run length of 12 hours (plotted by geomagnetic latitude). ]]</div></td></tr>
<tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l211">Line 211:</td>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>In 2012, geoelectric monitoring sites were installed at each of the three UK geomagnetic observatories. Data are now being recorded at these sites with the intention, over the long term, of comparing with the Nagycenk data, to provide a wider European scale view of surface geoelectric fields.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>In 2012, geoelectric monitoring sites were installed at each of the three UK geomagnetic observatories. Data are now being recorded at these sites with the intention, over the long term, of comparing with the Nagycenk data, to provide a wider European scale view of surface geoelectric fields.</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>For an initial look, in Figure 2.12 we show the distribution of electric field values from the Eskdalemuir observatory, for 1st January to 1st August 2013. It can be seen that there is a long tail in the distribution, in both the north (''E''x) and east (''E''y) components. Moreover there are clear difference between the Ex and Ey channels. This may be physical (local effects?) or may reflect issues with the instrumentation. We note that the local maxima during this time interval (of ~0.2V/km) compare with an estimated 5V/km for central Scotland during the October 2003 storm (Thomson et al., 2005<ref name="Thomson 2005">THOMSON, A W P, McKAY, A J, CLARKE, E, and REAY, S J. 2005). Surface electric fields and Geomagnetically Induced Currents in the Scottish Power grid during the 30 October 2003 geomagnetic storm, Space Weather, 3, S11002, doi:10.1029/2005SW000156.</ref>) and even estimates of ~20V/km for genuinely extreme events in resistive geological terranes (e.g. Pulkkinen et al., 2012<ref name="Pulkkinen 2012"><del style="font-weight: bold; text-decoration: none;">PULKKINEN, A, BERNEBEU, E, EICHNER, J, BEGGAN, C and THOMSON, A W P. 2012). Generation of 100-year geomagnetically induced current scenarios, Space Weather, 10, S04003, doi:10.1029/2011SW000750.</del></ref>).</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>For an initial look, in Figure 2.12 we show the distribution of electric field values from the Eskdalemuir observatory, for 1st January to 1st August 2013. It can be seen that there is a long tail in the distribution, in both the north (''E''x) and east (''E''y) components. Moreover there are clear difference between the Ex and Ey channels. This may be physical (local effects?) or may reflect issues with the instrumentation. We note that the local maxima during this time interval (of ~0.2V/km) compare with an estimated 5V/km for central Scotland during the October 2003 storm (Thomson et al., 2005<ref name="Thomson 2005">THOMSON, A W P, McKAY, A J, CLARKE, E, and REAY, S J. 2005). Surface electric fields and Geomagnetically Induced Currents in the Scottish Power grid during the 30 October 2003 geomagnetic storm, Space Weather, 3, S11002, doi:10.1029/2005SW000156.</ref>) and even estimates of ~20V/km for genuinely extreme events in resistive geological terranes (e.g. Pulkkinen et al., 2012<ref name="Pulkkinen 2012"></ref>).</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Over time, probably many years, we hope to construct a data set from which we can analyse the tail of the UK distributions using EVS, with a view to confirming, or otherwise, estimated extremes in modeled electric fields, such as given by Pulkkinen et al. (2012)<ref name="Pulkkinen 2012"></ref>, or the results obtained from Nagycenk.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Over time, probably many years, we hope to construct a data set from which we can analyse the tail of the UK distributions using EVS, with a view to confirming, or otherwise, estimated extremes in modeled electric fields, such as given by Pulkkinen et al. (2012)<ref name="Pulkkinen 2012"></ref>, or the results obtained from Nagycenk.</div></td></tr>
</table>Dbkhttp://earthwise.bgs.ac.uk/index.php?title=OR/14/004_Worst_case_scenario_research_at_BGS&diff=40808&oldid=prevDbk: 1 revision imported2019-05-28T12:23:32Z<p>1 revision imported</p>
<table style="background-color: #fff; color: #202122;" data-mw="interface">
<tr class="diff-title" lang="en">
<td colspan="1" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td>
<td colspan="1" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 13:23, 28 May 2019</td>
</tr><tr><td colspan="2" class="diff-notice" lang="en"><div class="mw-diff-empty">(No difference)</div>
</td></tr></table>Dbkhttp://earthwise.bgs.ac.uk/index.php?title=OR/14/004_Worst_case_scenario_research_at_BGS&diff=40807&oldid=prevAjhil at 12:15, 28 February 20192019-02-28T12:15:11Z<p></p>
<a href="http://earthwise.bgs.ac.uk/index.php?title=OR/14/004_Worst_case_scenario_research_at_BGS&diff=40807">Show changes</a>Ajhil