15

6  Indices

The  indices  presented  in  this  edition  (Files  wng96.k  to  wng99.k  and  Tables  4.x)  indicate  the  local
disturbances  of  the  geomagnetic  field  resulting  from  particle  radiation.  Their  meaning  in  detail:
K\  geomagnetic  three-hourly  index,  quasi-logarithmic  measure  of  the  maximum  disturbance  in
steps  of  0  to  9;  lower  limit  for  K-  9:  500  nT.
sum.  Sum  of  the  eight  three-hourly  indices  of  a  day.
Ak  Mean  value  of  the  equivalent  amplitudes  derived  from  the  eight  three-hourly  indices.  The
mean  value  of  the  daily  disturbance  of  the  geomagnetic  field  is  2  Ak  nT.
Ck:  daily  character  figure  derived  from  Ak  and  scaled  from  0.0  to  2.5.
C:  estimated  daily  character  figure;  scale:  0,  1,2.
The  indices  were  derived  using  the  lAGA-recommended  FMI-routine  (Häkkinen,  1992).

7  Contents  of  the  CDrom
The  enclosed  CDrom  contains  recorded  minute  values  as  well  as  derived  (hourly,  daily,  monthly)
mean  values  and  indices  for  the  reporting  period.  It  also  provides  recalculated  epoch  values  from
1939.5  on  and  those  of  Wilhelmhaven  Observatory  before  then,  a  complete  revised  data  set  of
hourly  means  (since  1943)  and  minute  values  starting  1981.  A  revised  set  of  indices  (since  1944)  is
also  included.
Using  a  visualisation  software,  the  one-minute,  hourly  and  daily  values  located  at
data/19YY/hourYY  and  minYY,  respectively,  can  be  displayed  as  graphs.

Files  and  Directories  on  the  Cdrom:

readme.txt:
tree.txt:

General  information
File  structure

1996,  1997,  1998  and  1999  data  (1  nT  and  0.T  values,  respectively):
yearb/:  Directory  containing  the  report  and  its  tables;  YY  means  96,  97,  98  or
99,  respectively
yearb/yearb.pdf:  This  report
yearb/info.txt:  Contains  information  about  instruments  and  data