@comment{{This file has been generated by bib2bib 1.99}}
@comment{{Command line: /soft/ukssdc/bin/bib2bib -c 'exists ukssdc_w' -s author --remove ukssdc_d --remove ukssdc_i --remove uk_first --remove uk_other -ob ukssdc_w.bib ukssdc.bib}}
  author = {Aruliah, A.L. and Farmer, A.D. and Fuller-Rowell, T.J. and
              Wild, M.N. and Hapgood, M. and Rees, D.},
  title = {An equinoctial asymmetry in the high-latitude thermosphere
              and ionosphere},
  journal = {Journal of Geophysical Research},
  pages = {15713--15722},
  year = {1996},
  month = jul,
  volume = {101},
  number = {A7},
  abstract = {A large equinoctial asymmetry has been observed in
              thermospheric winds and ion velocities at high latitude
              sites in northern Scandinavia. Throughout the solar cycle,
              average nighttime thermospheric meridional winds are larger
              in spring than autumn despite similar levels of solar
              insolation. The average ion velocities are also larger in
              spring than autumn at solar maximum, but at solar minimum
              this position is reversed. Numerical simulations of the
              thermosphere and ionosphere have not predicted such
              asymmetries because they generally assume forcing functions
              that are symmetric about the solstices. The proposed
              explanation lies in the annual and diurnal variation in
              solar wind-magnetosphere coupling caused by changes in the
              orientation of the geomagnetic pole, and hence the
              magnetosphere, with respect to the average orientation of
              the IMF (the Russell-McPherron effect). This causes a
              12-hour phase difference between the times of maximum solar
              wind-magnetosphere coupling at the two equinoxes. In
              addition, the orientation of the geomagnetic axis with
              respect to the average IMF is such that $ > 0$
              for the March equinox and $ < 0$ for
              September. This results in a further source of asymmetry of
              forcing of the high-latitude ionosphere as the result of
              electric fields associated with the four sign combinations
              of $B_{y}$ and $B_{z}$. Several predictions arise from the
              explanation given: for example, a high-latitude station
              measuring thermospheric neutral winds in Alaska,
              $180^{\circ}$ in longitude from Kiruna, might be expected to
              see nighttime thermospheric winds that are larger in the
              autumn than in the spring.},
  url = {},
  ukssdc_w = {}
  author = {Aruliah, A.L. and Schoendorf, J. and Aylward, A.D. and Wild,
  title = {Modelling the High-Latitude Equinoctial Asymmetry},
  journal = {Journal of Geophysical Research},
  pages = {27207--27216},
  year = {1997},
  volume = {102},
  number = {A12},
  abstract = {Fabry-Perot Interferometer measurements of neutral winds and
              European Incoherent SCATter radar measurements of plasma
              velocities have shown a significant equinoctial asymmetry in
              the average behavior of the thermosphere and ionosphere
              above northern Scandinavia. Existing standard models of the
              upper atmosphere use forcing functions that are symmetric
              about the solstices, therefore these observations are
              unexpected. It is suggested that the asymmetry arises from
              the diurnal variation in the cross polar cap potential
              difference (CPCPD) because there is a 12 hour phase
              difference between the variations at the March and September
              equinoxes. The variation in the CPCPD is caused by an annual
              and diurnal variation in the orientation of the
              magnetosphere with respect to the interplanetary magnetic
              field. This is known as the Russell-McPherron(R-M)
              effect. The plausibility of this explanation of the
              equinoctial asymmetry in thermospheric winds is supported by
              investigation of the effect of their geomagnetic history,
              i.e., the repercussions on the winds of the activity levels
              in the few hours prior to the observation. The consequences
              of the R-M effect have been simulated in the University
              College London/Sheffield/Space Environment Laboratory
              coupled thermosphere-ionosphere model by imposing a
              diurnally varying high-latitude electric field pattern. The
              results are used to test the predictions, given in an
              earlier paper, of the average behavior expected at other
              high-latitude sites. A corollary to the study is that the
              evidence presented here implies that the auroral oval may be
              smaller at solar minimum, which is also unexpected.},
  ukssdc_w = {}
  author = {D. M. Willis and R. Henwood and M.N. Wild and H.E. Coffey
              and W.F. Denig and E.H. Erwin and D. V. Hoyt},
  title = {The Greenwich Photo-heliographic Results (1874--1976):
              Procedures for Checking and Correcting the Sunspot Digital
  journal = {Solar Physics},
  year = 2013,
  abstract = {Attention is drawn to the existence of errors in the
              original digital dataset containing sunspot data extracted
              from certain sections of the printed Greenwich
              Photo-heliographic Results (GPR) 1874--1976. Calculating
              the polar coordinates from the heliographic coordinates and
              comparing them with the recorded polar coordinates reveals
              that there are both isolated and systematic errors in the
              original sunspot digital dataset, particularly during the
              early years (1874--1914). It should be noted that most of
              these errors are present in the compiled sunspot digital
              dataset and not in the original printed copies of the
              Greenwich Photo-heliographic Results. Surprisingly, many of
              the errors in the digitised positions of sunspot groups are
              apparently in the measured polar coordinates, not the
              derived heliographic coordinates. The mathematical equations
              that are used to convert between heliographic and polar
              coordinate systems are formulated and then used to calculate
              revised (digitised) polar coordinates for sunspot groups, on
              the assumption that the heliographic coordinates of every
              sunspot group are correct. The additional complication of
              requiring accurate solar ephemerides in order to solve the
              mathematical equations is discussed in detail. It is shown
              that the isolated and systematic errors, which are prevalent
              in the sunspot digital dataset during the early years,
              disappear if revised polar coordinates are used instead. A
              comprehensive procedure for checking the original sunspot
              digital dataset is formulated in an Appendix.},
  doi = {10.1007/s11207-013-0312-x},
  url = {},
  ukssdc_w = {}
  author = {D.M. Willis and H.E. Coffey and R. Henwood and E.H. Erwin
              and D.V. Hoyt and M.N. Wild and W.F. Denig},
  title = {The Greenwich Photo-heliographic Results (1874--1976):
              Summary of the Observations, Applications, Datasets,
              Definitions and Errors},
  journal = {Solar Physics},
  year = 2013,
  abstract = {The measurements of sunspot positions and areas that were
              published initially by the Royal Observatory, Greenwich, and
              subsequently by the Royal Greenwich Observatory (RGO), as
              the Greenwich Photo-heliographic Results (GPR), 1874--1976,
              exist in both printed and digital forms. These printed and
              digital sunspot datasets have been archived in various
              libraries and data centres. Unfortunately, however,
              typographic, systematic and isolated errors can be found in
              the various datasets. The purpose of the present paper is to
              begin the task of identifying and correcting these
              errors. In particular, the intention is to provide in one
              foundational paper all the necessary background information
              on the original solar observations, their various
              applications in scientific research, the format of the
              different digital datasets, the necessary definitions of the
              quantities measured, and the initial identification of
              errors in both the printed publications and the digital
              datasets. Two companion papers address the question of
              specific identifiable errors; namely, typographic errors in
              the printed publications, and both isolated and systematic
              errors in the digital datasets. The existence of two
              independently prepared digital datasets, which both contain
              information on sunspot positions and areas, makes it
              possible to outline a preliminary strategy for the
              development of an even more accurate digital
              dataset. Further work is in progress to generate an
              extremely reliable sunspot digital dataset, based on the
              programme of solar observations supported for more than a
              century by the Royal Observatory, Greenwich, and the Royal
              Greenwich Observatory. This improved dataset should be of
              value in many future scientific investigations.},
  doi = {10.1007/s11207-013-0311-y},
  url = {},
  ukssdc_w = {}
  author = {Davis, C. J. and Wild, M. N. and Lockwood, M. and Tulunay,
                 Y. K.},
  affiliation = {Rutherford Appletpn Laboratory Chilton Didcot OX11 OQX
                 United Kingdom},
  title = {Ionospheric and geomagnetic responses to changes in {IMF}
                 ${B}_{z}$: a superposed epoch study},
  journal = {Annales Geophysicae},
  publisher = {Springer Berlin / Heidelberg},
  issn = {0992-7689},
  keyword = {Earth and Environmental Science},
  pages = {217-230},
  volume = 15,
  issue = 2,
  url = {},
  doi = {10.1007/s00585-997-0217-9},
  abstract = {Superposed epoch studies have been carried out in order to
                 determine the ionospheric response at mid-latitudes to
                 southward turnings of the interplanetary magnetic field
                 (IMF). This is compared with the geomagnetic response, as
                 seen in the indices ${K}_{p}$, ${AE}$ and $Dst$. The solar
                 wind, IMF and geomagnetic data used were hourly averages
                 from the years 1967--1989 and thus cover a full 22-year
                 cycle in the solar magnetic field. These data were divided
                 into subsets, determined by the magnitudes of the southward
                 turnings and the concomitant increase in solar wind
                 pressure. The superposed epoch studies were carried out
                 using the time of the southward turning as time zero. The
                 response of the mid-latitude ionosphere is studied by
                 looking at the F-layer critical frequencies, $f_{o}F2$, from
                 hourly soundings by the Slough ionosonde and their deviation
                 from the monthly median values, ${\delta}f_{o}F2$. For the
                 southward turnings with a change in $B_{z}$ of
                 ${\delta}B_{z}>11.5$ nT accompanied by a solar wind dynamic
                 pressure $P$ exceeding 5 nPa, the F region critical
                 frequency, $f_{o}F2$, shows a marked decrease, reaching a
                 minimum value about 20 h after the southward turning. This
                 recovers to pre-event values over the subsequent 24 h, on
                 average. The $Dst$ index shows the classic storm-time
                 decrease to about -60 nT. Four days later, the index has
                 still to fully recover and is at about -25 nT. Both the
                 $K_{p}$ and $AE$ indices show rises before the southward
                 turnings, when the IMF is strongly northward but the solar
                 wind dynamic pressure is enhanced. The average $AE$ index
                 does register a clear isolated pulse (averaging 650 nT for 2
                 h, compared with a background peak level of near 450 nT at
                 these times) showing enhanced energy deposition at high
                 latitudes in substorms but, like $K_{p}$, remains somewhat
                 enhanced for several days, even after the average IMF has
                 returned to zero after 1 day. This $AE$ background decays
                 away over several days as the $Dst$ index recovers,
                 indicating that there is some contamination of the currents
                 observed at the $AE$ stations by the continuing enhanced
                 equatorial ring current. For data averaged over all seasons,
                 the critical frequencies are depressed at Slough by 1.3 MHz,
                 which is close to the lower decile of the overall
                 distribution of ${\delta}f_{o}F2$ values. Taking 30-day
                 periods around summer and winter solstice, the largest
                 depression is 1.6 and 1.2 MHz, respectively. This seasonal
                 dependence is confirmed by a similar study for a Southern
                 Hemisphere station, Argentine Island, giving peak
                 depressions of 1.8 MHz and 0.5 MHz for summer and
                 winter. For the subset of turnings where
                 ${\delta}B_{z}>11.5$ nT and $P<= 5$ nPa, the response of the
                 geomagnetic indices is similar but smaller, while the change
                 in ${\delta}f_{o}F2$ has all but disappeared. This confirms
                 that the energy deposited at high latitudes, which leads to
                 the geomagnetic and ionospheric disturbances following a
                 southward turning of the IMF, increases with the energy
                 density (dynamic pressure) of the solar wind flow. The
                 magnitude of all responses are shown to depend on
                 ${\delta}B_{z}$. At Slough, the peak depression always
                 occurs when Slough rotates into the noon sector. The largest
                 ionospheric response is for southward turnings seen between
                 15--21 UT.},
  ukssdc_w = {},
  pdf = {},
  year = 1997
  author = {E.H. Erwin and H.E. Coffey and W.F. Denig and D.M. Willis
              and R. Henwood and M.N. Wild},
  title = {The Greenwich Photo-heliographic Results (1874--1976):
              Initial Corrections to the Printed Publications},
  journal = {Solar Physics},
  year = {2013},
  abstract = {A new sunspot and faculae digital dataset for the interval
              1874--1955 has been prepared under the auspices of the NOAA
              National Geophysical Data Center (NGDC). This digital
              dataset contains measurements of the positions and areas of
              both sunspots and faculae published initially by the Royal
              Observatory, Greenwich, and subsequently by the Royal
              Greenwich Observatory (RGO), under the title Greenwich
              Photo-heliographic Results (GPR), 1874--1976. Quality
              control (QC) procedures based on logical consistency have
              been used to identify the more obvious errors in the RGO
              publications. Typical examples of identifiable errors are
              North versus South errors in specifying heliographic
              latitude, errors in specifying heliographic (Carrington)
              longitude, errors in the dates and times, errors in sunspot
              group numbers, arithmetic errors in the summation process,
              and the occasional omission of solar ephemerides. Although
              the number of errors in the RGO publications is remarkably
              small, an initial table of necessary corrections is provided
              for the interval 1874--1917. Moreover, as noted in the
              preceding companion papers, the existence of two
              independently prepared digital datasets, which both contain
              information on sunspot positions and areas, makes it
              possible to outline a preliminary strategy for the
              development of an even more accurate digital
              dataset. Further work is in progress to generate an
              extremely reliable sunspot digital dataset, based on the
              long programme of solar observations supported first by the
              Royal Observatory, Greenwich, and then by the Royal
              Greenwich Observatory.},
  doi = {10.1007/s11207-013-0310-z},
  url = {},
  ukssdc_w = {}
  author = {Hapgood, M.A.},
  editor = {Heck, A. and Murtagh, F.},
  title = {Multi-step queries: the need for a correlation environment},
  booktitle = {Adding Intelligence to Information Retrieval: the Case of
               Astronomy and Related Space Sciences},
  year = {1993},
  month = jan,
  publisher = {Kluwer},
  address = {Dordrecht},
  ukssdc_w = {}
  author = {Hapgood, M.A. and Lockwood, M. and Bowe, G.A. and Willis,
              D.M. and Tulunay, Y.K.},
  title = {Variability of the interplanetary medium at 1 a.u. over 24
              years: 1963--1986},
  journal = {Planetary and Space Science},
  pages = {411--423},
  year = {1991},
  month = mar,
  volume = {39},
  number = {3},
  abstract = {A survey is presented of hourly averages of observations of
              the interplanetary medium, made by satellites close to the
              Earth (i.e. at 1 a.u.) in the years 1963-1986. This survey
              therefore covers two complete solar cycles (numbers 20 and
              21). The distributions and solar-cycle variations of IMF
              field strength, $B$, and its northward component (in GSM
              coordinates), $B_{z}$, and of the solar-wind density, n,
              speed, $\upsilon$, and dynamic pressure, P, are
              discussed. Because of their importance to the terrestrial
              magnetosphere/ionosphere, particular attention is given to
              $B_{z}$ and P. The solar-cycle variation in the magnitude
              and variability of $B_{z}$, previously reported for cycle
              20, is also found for cycle 21. However, the solar-wind data
              show a number of differences between cycles 20 and 21. The
              average dynamic pressure is found to show a solar-cycle
              variation and a systematic increase over the period of the
              survey. The minimum of dynamic pressure at sunspot maximum
              is mainly due to reduced solar-wind densities in cycle 20,
              but lower solar-wind speed in cycle 21 is a more significant
              factor. The distribution of the duration of periods of
              stable polarity of the IMF $B_{z}$ component shows that the
              magnetosphere could achieve steady state for only a small
              fraction of the time and there is some evidence for a
              solar-cycle variation in this fraction. It is also found
              that the polarity changes in the IMF $B_{z}$ fall into two
              classes: one with an associated change in solar-wind dynamic
              pressure, the other without such a change. However, in only
              20\% of cases does the dynamic pressure change exceed 50\%.},
  ukssdc_w = {}
  author = {Hewish, A. and others},
  title = {Synoptic data for Solar-Terrestrial Monitoring},
  institution = {The Royal Society},
  year = {1992},
  month = sep,
  address = {London},
  ukssdc_w = {}
  author = {Hisashi Hayakawa and Yusuke Ebihara and David M. Willis and
              Kentaro Hattori and Alessandra S. Giunta and Matthew N.
              Wild and Satoshi Hayakawa and Shin Toriumi and Yasuyuki
              Mitsuma and Lee T. Macdonald and Kazunari Shibata and Sam
              M. Silverman},
  title = {The Great Space Weather Event during 1872 February Recorded
              in East Asia},
  journal = {The Astrophysical Journal},
  volume = 862,
  number = 1,
  pages = 15,
  url = {},
  doi = {10.3847/1538-4357/aaca40},
  year = 2018,
  abstract = {The study of historical great geomagnetic storms is crucial
              for assessing the possible risks to the technological
              infrastructure of a modern society, caused by extreme
              space-weather events. The normal benchmark has been the
              great geomagnetic storm of 1859 September, the so-called
              ''Carrington Event.'' However, there are numerous records of
              another great geomagnetic storm in 1872 February. This
              storm, which occurred about 12 years after the Carrington
              Event, resulted in comparable magnetic disturbances and
              auroral displays over large areas of the Earth. We have
              revisited this great geomagnetic storm in terms of the
              auroral and sunspot records in historical documents from
              East Asia. In particular, we have surveyed the auroral
              records from East Asia and estimated the equatorward
              boundary of the auroral oval to be near $24.2^{\circ}$ invariant
              latitude, on the basis that the aurora was seen near the
              zenith at Shanghai ($20^{\circ}$ magnetic latitude, MLAT). These
              results confirm that this geomagnetic storm of 1872 February
              was as extreme as the Carrington Event, at least in terms of
              the equatorward motion of the auroral oval. Indeed, our
              results support the interpretation of the simultaneous
              auroral observations made at Bombay ($10^{\circ}$ MLAT). The East
              Asian auroral records have indicated extreme brightness,
              suggesting unusual precipitation of high-intensity,
              low-energy electrons during this geomagnetic storm. We have
              compared the duration of the East Asian auroral displays
              with magnetic observations in Bombay and found that the
              auroral displays occurred in the initial phase, main phase,
              and early recovery phase of the magnetic storm.},
  ukssdc_w = {}
  author = {King, J.W.},
  title = {Solar radiation changes and the weather},
  journal = {Nature},
  pages = {443--446},
  year = {1973},
  month = oct,
  volume = {245},
  ukssdc_w = {}
  author = {Liu, C. and Smith, P.A. and King, J.W.},
  title = {A new solar index which leads to improved foF2 predictions
              using the CCIR Atlas},
  journal = {Telecommunications Journal},
  pages = {408--414},
  year = {1983},
  volume = {50},
  number = {VIII},
  ukssdc_w = {}
  author = {Lockwood, M. and Rouillard, A.P. and Finch, I. and Stamper,
  title = {{Comment on ``The IDV index: Its derivation and use in
              inferring long-term variations of the interplanetary
              magnetic field strength'' by Leif Svalgaard and Edward
              W. Cliver}},
  journal = {Journal of Geophysical Research (Space Physics)},
  year = 2006,
  month = sep,
  volume = 111,
  number = {A10},
  pages = {9109-+},
  doi = {10.1029/2006JA011640},
  adsurl = {},
  adsnote = {Provided by the Smithsonian/NASA Astrophysics Data System},
  ukssdc_w = {}
  author = {Lockwood, M. and Stamper, R.},
  title = {Long-term drift of the coronal source magnetic flux and the
              total solar irradiance},
  journal = {Geophysical Research Letters},
  pages = {2461-2464},
  year = 1999,
  month = {august},
  volume = 26,
  number = 16,
  ukssdc_w = {},
  abstract = {We test the method of Lockwood et al. [1999] for deriving
              the coronal source flux from the geomagnetic aa index and
              show it to be accurate to within 12\% for annual means and
              4.5\% for averages over a sunspot cycle. Using data from
              four solar constant monitors during 1981--1995, we find a
              linear relationship between this magnetic flux and the total
              solar irradiance. From this correlation, we show that the
              131\% rise in the mean coronal source field over the
              interval 1901--1995 corresponds to a rise in the average
              total solar irradiance of $\Delta I = 1.65 \pm 0.23
  url = {grlcover.html}
  author = {Lockwood, M. and Stamper, R. and Wild, M.},
  title = {A Doubling of the Sun's Coronal Magnetic Field during the
              Last 100 Years},
  journal = {Nature},
  volume = 399,
  pages = {437--439},
  year = 1999,
  month = {june},
  abstract = {The solar wind is an extended ionized gas of very high
              electrical conductivity, and therefore drags some magnetic
              flux out of the Sun to fill the heliosphere with a weak
              interplanetary magnetic field,. Magnetic reconnection -- the
              merging of oppositely directed magnetic fields -- between
              the interplanetary field and the Earth's magnetic field
              allows energy from the solar wind to enter the near-Earth
              environment. The Sun's properties, such as its luminosity,
              are related to its magnetic field, although the connections
              are still not well understood,. Moreover, changes in the
              heliospheric magnetic field have been linked with changes in
              total cloud cover over the Earth, which may influence global
              climate. Here we show that measurements of the near-Earth
              interplanetary magnetic field reveal that the total magnetic
              flux leaving the Sun has risen by a factor of 1.4 since
              1964: surrogate measurements of the interplanetary magnetic
              field indicate that the increase since 1901 has been by a
              factor of 2.3. This increase may be related to chaotic
              changes in the dynamo that generates the solar magnetic
              field. We do not yet know quantitatively how such changes
              will influence the global environment.},
  ukssdc_w = {},
  pdf = {},
  url = {},
  doi = {10.1038/20867}
  author = {Lockwood, M. and Stamper, R. and Wild, M.N. and Opgenoorth,
  title = {Ground-Based Measurements in Support of CLUSTER: An On-Line
                 Planning Procedure},
  institution = {DRAL},
  year = {1995},
  month = feb,
  number = {RAL-95-018},
  ukssdc_w = {}
  author = {Lockwood, M. and Wild, M.N. and Cowley, S.W.H.},
  title = {The Onset and Expansion of Enhanced Ionospheric Convection
              Following a Southward Turning of the IMF},
  journal = {Journal of Geophysical Research},
  year = {1999},
  note = {submitted},
  ukssdc_w = {}
  author = {Lockwood, M. and Wild, M.N. and Stamper, R. and Grande, M.},
  title = {Predicting solar disturbance effects on navigation systems},
  booktitle = {Journal of Navigation},
  pages = {203--216},
  year = {1999},
  volume = {52},
  ukssdc_w = {}
  author = {Opgenoorth, H.J. and Persson, M.A.L. and Lockwood, M. and
               Stamper, R. and Wild, M.N. and Pellinen, R. and Pulkkinen,
               T. and Kauristie, K. and Hughes, T. and Kamide, Y.},
  editor = {Lockwood, M. and Wild, M.N. and Opgenoorth, H.J.},
  title = {A New Family of Geomagnetic Disturbance Indices},
  booktitle = {Satellite - Ground Based Coordination Sourcebook},
  pages = {49--62},
  year = {1997},
  publisher = {ESA},
  volume = {SP-1198},
  ukssdc_w = {}
  author = {Pulkkinen, T.I. and Nevanlinna, H. and Pulkkinen, P.J. and
              Lockwood M.},
  title = {The Sun-Earth Connection in Time Scales from Years to Decades and Centuries},
  journal = {Space Science Reviews},
  year = 2001,
  volume = 95,
  number = {1-2},
  pages = {625--637},
  month = jan,
  ukssdc_w = {},
  abstract = {The Sun--Earth connection is studied using long-term
              measurements from the Sun and from the Earth. The auroral
              activity is shown to correlate to high accuracy with the
              smoothed sunspot numbers. Similarly, both geomagnetic
              activity and global surface temperature anomaly can be
              linked to cyclic changes in the solar activity. The
              interlinked variations in the solar magnetic activity and in
              the solar irradiance cause effects that can be observed both
              in the Earth's biosphere and in the electromagnetic
              environment. The long-term data sets suggest that the
              increase in geomagnetic activity and surface temperatures
              are related (at least partially) to longer-term solar
              variations, which probably include an increasing trend
              superposed with a cyclic behavior with a period of about 90
  author = {Saunders, M.A. and Lockwood, M. and Wild, M.N.},
  title = {The semi-annual variation in great geomagnetic storms},
  year = {1993},
  month = mar,
  note = {Submitted to Annales Geophysicae},
  ukssdc_w = {}
  author = {Stamper, R.},
  title = {Improved prediction of I_{F2} and I_{G} indices using neural
  journal = {IEEE Proc.-Microw. Antennas Propag.},
  pages = {341--346},
  year = {1996},
  month = aug,
  volume = {143},
  number = {4},
  ukssdc_w = {}
  author = {Stamper, R. and Lockwood, M. and Wild, M.N. and Clark,
  title = {Solar Causes of the Long-Term Increase in Geomagnetic
  journal = {Journal of Geophysical Research},
  pages = {28325--28342},
  year = {1999},
  month = dec,
  volume = {104},
  number = {A12},
  ukssdc_w = {},
  abstract = {We analyze the causes of the century-long increase in
              geomagnetic activity, quantified by annual means of the {\it
              aa} index, using observations of interplanetary space,
              galactic cosmic rays, the ionosphere, and the auroral
              electrojet, made during the last three solar cycles. The
              effects of changes in ionospheric conductivity, the Earth's
              dipole tilt, and magnetic moment are shown to be small; only
              changes in near-Earth interplanetary space make a
              significant contribution to the long-term increase in
              activity. We study the effects of the interplanetary medium
              by applying dimensional analysis to generate the optimum
              solar wind-magnetosphere energy coupling function, having an
              unprecedentedly high correlation coefficient of
              0.97. Analysis of the terms of the coupling function shows
              that the largest contributions to the drift in activity over
              solar cycles 20--22 originate from rises in the average
              interplanetary magnetic field (IMF) strength, solar wind
              concentration, and speed; average IMF orientation has grown
              somewhat less propitious for causing geomagnetic
              activity. The combination of these factors explains almost
              all of the 39\% rise in {\it aa} observed over the last
              three solar cycles. Whereas the IMF strength varies
              approximately in phase with sunspot numbers, neither its
              orientation nor the solar wind density shows any coherent
              solar cycle variation. The solar wind speed peaks strongly
              in the declining phase of even-numbered cycles and can be
              identified as the chief cause of the phase shift between the
              sunspot numbers and the {\it aa} index. The rise in the IMF
              magnitude, the largest single contributor to the drift in
              geomagnetic activity, is shown to be caused by a rise in the
              solar coronal magnetic field, consistent with a rise in the
              coronal source field, modeled from photospheric
              observations, and an observed decay in cosmic ray fluxes.}
  author = {Stamper, R. and Wild, M. and Lockwood, M.},
  editor = {Lockwood, M. and Wild, M.N. and Opgenoorth, H.J.},
  title = {An On-Line Directory of Ground-Based STP Observatories},
  booktitle = {Satellite - Ground Based Coordination Sourcebook},
  pages = {367--407},
  year = {1997},
  publisher = {ESA},
  volume = {SP-1198},
  ukssdc_w = {}
  author = {Szuszczewicz, E.P. and Blanchard, P. and Wilkinson, P. and
              Crowley, G. and Fuller-Rowell, T. and Richards, P. and Abdu,
              M. and Bullett, T. and Hanbaba, R. and Lebreton, J.P. and
              Lester, M. and Lockwood, M. and Millward, G. and Wild,
              M. and Pulinets, S. and Reddy, B.M. and Stanislawska, I. and
              Vannaroni, G. and Zolesi, B.},
  title = {The First Realtime Worldwide Ionospheric Prediction Network:
              An Advance in Support of Spaceborne Experimentation, On-Line
              Model Validation, and Space Weather},
  journal = {Geophysical Research Letters},
  pages = {449-452},
  year = {1998},
  month = {feb},
  volume = {25},
  number = {4},
  abstract = {We report on the first realtime ionospheric predictions
              network and its capabilities to ingest a global database and
              forecast F-layer characteristics and ``in situ'' electron
              densities along the track of an orbiting spacecraft. A
              global network of ionosonde stations reported
              around-the-clock observations of F-region heights and
              densities, and an on-line library of models provided
              forecasting capabilities. Each model was tested against the
              incoming data; relative accuracies were intercompared to
              determine the best overall fit to the prevailing conditions;
              and the best-fit model was used to predict ionospheric
              conditions on an orbit-to-orbit basis for the 12-hour period
              following a twice-daily model test and validation
              procedure. It was found that the best-fit model often
              provided averaged (i.e., climatologically-based) accuracies
              better than 5\% in predicting the heights and critical
              frequencies of the F-region peaks in the latitudinal domain
              of the TSS-1R flight path. There was a sharp contrast,
              however, in model-measurement comparisons involving
              predictions of actual, unaveraged, along-track densities at
              the 295 km orbital altitude of TSS-1R. In this case, extrema
              in the first-principle models varied by as much as an order
              of magnitude in density predictions, and the best-fit models
              were found to disagree with the ``in situ'' observations of
              Ne by as much as 140\%. The discrepancies are interpreted as
              a manifestation of difficulties in accurately and
              self-consistently modeling the external controls of solar
              and magnetospheric inputs and the spatial and temporal
              variabilities in electric fields, thermospheric winds,
              plasmaspheric fluxes, and chemistry.},
  ukssdc_w = {}
  author = {Wild, M.N. and Lockwood, M.},
  editor = {Lockwood, M. and Wild, M.N. and Opgenoorth, H.J.},
  title = {Cluster-Ground Based Data Centre},
  booktitle = {Satellite - Ground Based Coordination Sourcebook},
  pages = {361--366},
  year = {1997},
  publisher = {ESA},
  volume = {SP-1198},
  ukssdc_w = {}
  author = {Willis, D. M.  and Wild, M. N.  and Appleby, G. M.  and
              Macdonald, L. T.},
  title = {The Greenwich Photo-heliographic Results
              (1874{\thinspace}--{\thinspace}1885): Observing Telescopes,
              Photographic Processes, and Solar Images},
  journal = {Solar Physics},
  year = {2016},
  pages = {1--34},
  abstract = {Potential sources of inhomogeneity in the sunspot
              measurements published by the Royal Observatory, Greenwich,
              during the early interval 1874{\thinspace}--{\thinspace}1885
              are examined critically. Particular attention is paid to
              inhomogeneities that might arise because the sunspot
              measurements were derived from solar photographs taken at
              various contributing solar observatories, which used
              different telescopes, experienced different seeing
              conditions, and employed different photographic
              processes. The procedures employed in the Solar Department
              at the Royal Greenwich Observatory (RGO), Herstmonceux,
              during the final phase of sunspot observations provide a
              modern benchmark for interpreting the early sunspot
              measurements. The different observing telescopes used at the
              contributing solar observatories during the interval
              1874{\thinspace}--{\thinspace}1885 are discussed in detail,
              using information gleaned from the official RGO publications
              and other relevant historical documents. Likewise, the
              different photographic processes employed at the different
              solar observatories are reviewed carefully. The procedures
              used by RGO staff to measure the positions and areas of
              sunspot groups on photographs of the Sun having a nominal
              radius of either four or eight inches are described. It is
              argued that the learning curve for the use of the Kew
              photoheliograph at the Royal Observatory, Greenwich,
              actually commenced in 1858, not 1874. The RGO daily number
              of sunspot groups is plotted graphically and analysed
              statistically. Similarly, the changes of metadata at each
              solar observatory are shown on the graphical plots and
              analysed statistically. It is concluded that neither the
              interleaving of data from the different solar observatories
              nor the changes in metadata invalidates the RGO count of the
              number of sunspot groups, which behaves as a
              quasi-homogeneous time series. Furthermore, it is emphasised
              that the correct treatment of days without photographs is
              quite crucial to the correct calculation of Group Sunspot
  issn = {1573-093X},
  doi = {10.1007/s11207-016-0894-1},
  url = {},
  pdf = {},
  ukssdc_w = {}
  author = {Willis, D. M.  and Wild, M. N.  and Warburton, J. S.},
  title = {Re-examination of the Daily Number of Sunspot Groups for the
              Royal Observatory, Greenwich
  journal = {Solar Physics},
  year = {2016},
  pages = {1--34},
  abstract = {The daily number of sunspot groups on the solar disk, as
              recorded by the programme of sunspot observations performed
              under the aegis of the Royal Observatory, Greenwich, UK, and
              subsequently the Royal Greenwich Observatory (RGO), is
              re-examined for the interval
              1874\thinspace--\thinspace1885. The motivation for this
              re-examination is the key role that the RGO number of
              sunspot groups plays in the calculation of Group Sunspot
              Numbers (Hoyt and Schatten in Solar Phys.  179, 189, 1998a;
              Solar Phys.  181, 491, 1998b). A new dataset has been
              derived for the RGO daily number of sunspot groups in the
              interval 1874\thinspace--\thinspace1885. This new dataset
              attempts to achieve complete consistency between the sunspot
              data presented in the three main sections of the RGO
              publications and also incorporates all known errata and
              additions. It is argued that days for which no RGO solar
              photograph was acquired originally should be regarded,
              without exception, as being days without meaningful sunspot
              data. The daily number of sunspot groups that Hoyt and
              Schatten assign to days without RGO photographs is
              frequently just a lower limit. Moreover, in the absence of a
              solar photograph, the daily number of sunspot groups is
              inevitably uncertain because of the known frequent
              occurrence of sunspot groups that exist for just a single
              day. The elimination of days without photographs changes the
              list of inter-comparison days on which both the primary RGO
              observer and a specified secondary comparison observer saw
              at least one sunspot group. The resulting changes in the
              personal correction factors of secondary observers then
              change the personal correction factors of overlapping
              tertiary observers, etc. In this way, numerical changes in
              the personal correction factors of secondary observers
              propagate away from the interval
              1874\thinspace--\thinspace1885, thereby potentially changing
              the arithmetical calculation of Group Sunspot Numbers over
              an appreciably wider time interval.},
  issn = {1573-093X},
  doi = {10.1007/s11207-016-0856-7},
  url = {},
  pdf = {},
  ukssdc_w = {}
  author = {Willis, D.M. and Davda, V.N. and Stephenson, F.Richard},
  title = {Comparison between Oriental and Occidental Sunspot
  journal = {Quarterly Journal of the Royal Astronomical Society},
  pages = {189--229},
  year = {1996},
  month = {jun},
  volume = {37},
  ukssdc_w = {}
  author = {Willis, D.M. and Henwood, R. and Stephenson, F.R.},
  title = {The presence of large sunspots near the central solar
              meridian at the times of major geomagnetic storms},
  journal = {Annales Geophysicae},
  year = 2009,
  volume = 27,
  pages = {185--197},
  number = {1},
  url = {},
  month = jan,
  abstract = {A further study is made of the validity of a technique
              developed by the authors to identify historical occurrences
              of intense geomagnetic storms, which is based on finding
              approximately coincident observations of sunspots and
              aurorae recorded in East Asian histories. Previously, the
              validity of this technique was corroborated using scientific
              observations of aurorae in Japan during the interval
              1957--2004 and contemporaneous white-light images of the Sun
              obtained by the Royal Greenwich Observatory, the Big Bear
              Solar Observatory, the Debrecen Heliophysical Observatory,
              and the Solar and Heliospheric Observatory spacecraft. The
              present investigation utilises a list of major geomagnetic
              storms in the interval 1868--2008, which is based on the
              magnitude of the AA* magnetic index, and reconstructed solar
              images based on the sunspot observations acquired by the
              Royal Greenwich Observatory during the shorter interval
              1874--1976. It is found that a sunspot large enough to be
              seen with the unaided eye by an "experienced" observer was
              located reasonably close to the central solar meridian for
              almost 90\% of these major geomagnetic storms. Even an
              "average" observer would easily achieve a corresponding
              success rate of 70\% and this success rate increases to
              about 80\% if a minority of ambiguous situations are
              interpreted favourably. The use of information on major
              geomagnetic storms, rather than modern auroral observations
              from Japan, provides a less direct corroboration of the
              technique for identifying historical occurrences of intense
              geomagnetic storms, if only because major geomagnetic storms
              do not necessarily produce auroral displays over East
              Asia. Nevertheless, the present study provides further
              corroboration of the validity of the original technique for
              identifying intense geomagnetic storms. This additional
              corroboration of the original technique is important because
              early unaided-eye observations of sunspots and aurorae
              provide the only possible means of identifying individual
              geomagnetic storms during the greater part of the past two
  ukssdc_w = {}
  user = {},
  author = {Willis, D.M. and Stephenson, F. R. and Huiping Fang},
  title = {Sporadic aurorae observed in East Asia},
  journal = {Annales Geophysicae},
  volume = {25},
  number = {2},
  pages = {417-436},
  year = {2007},
  month = mar,
  url = {},
  pdf = {},
  ukssdc_w = {},
  abstract = {All the accessible auroral observations recorded in Chinese
              and Japanese histories during the interval AD 1840--1911 are
              investigated in detail. Most of these auroral records have
              never been translated into a Western language before. The
              East Asian auroral reports provide information on the date
              and approximate location of each auroral observation,
              together with limited scientific information on the
              characteristics of the auroral luminosity such as colour,
              duration, extent, position in the sky and approximate time
              of occurrence. The full translations of the original Chinese
              and Japanese auroral records are presented in an appendix,
              which contains bibliographic details of the various
              historical sources. (There are no known reliable Korean
              observations during this interval.) A second appendix
              discusses a few implausible "auroral" records, which have
              been rejected. The salient scientific properties of all
              exactly dated and reliable East Asian auroral observations
              in the interval AD 1840--1911 are summarised succinctly. By
              comparing the relevant scientific information on exactly
              dated auroral observations with the lists of great
              geomagnetic storms compiled by the Royal Greenwich
              Observatory, and also the tabulated values of the Ak
              (Helsinki) and aa (Greenwich and Melbourne) magnetic
              indices, it is found that 5 of the great geomagnetic storms
              (aa>150 or Ak>50) during either the second half of the
              nineteenth century or the first decade of the twentieth
              century are clearly identified by extensive auroral displays
              observed in China or Japan. Indeed, two of these great
              storms produced auroral displays observed in both countries
              on the same night.  Conversely, at least 29 (69\%) of the 42
              Chinese and Japanese auroral observations occurred at times
              of weak-to-moderate geomagnetic activity (aa or
              Ak$\leq$50). It is shown that these latter auroral displays
              are very similar to the more numerous (about 50) examples of
              sporadic aurorae observed in the United States during the
              interval AD 1880--1940. The localised nature and spatial
              structure of some sporadic aurorae observed in East Asia is
              indicated by the use of descriptive terms such as
              "lightning", "rainbow", "streak" and "grid".}
  author = {Willis, D.M. and Tulunay, Y.K.},
  title = {Statistics of the largest sunspot and facular areas per
              solar cycle},
  journal = {Solar Physics},
  pages = {237--246},
  year = {1979},
  volume = {64},
  abstract = {The paper uses the statistics of extreme values to
              investigate the statistical properties of the largest areas
              of sunspots and photospheric faculae per solar cycle. The
              largest values of the synodic-solar-rotation mean areas of
              umbrae, whole spots and faculae, which have been recorded
              for nine solar cycles are shown to comply with the general
              form of the extreme value probability function. Empirical
              expressions are derived for the three extreme value
              populations from which the characteristic statistic
              parameters, namely the mode, median, mean and standard
              deviation, can be calculated for each population. It is
              found that extreme areas of umbrae and whole spots have a
              diversion comparable to that found by Siscoe for the extreme
              values of sunspot number whereas the extreme areas of
              faculae have a smaller dispersion which is comparable to
              that found by Siscoe for the largest geomagnetic storm per
              solar cycle.},
  ukssdc_w = {}