Format Description for Hourly Mean Values of
Geomagnetic Field Elements — WDC-format

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Columns  Format        Description
======================================================================
  1-3      A3   Observatory 3-letter code.
  4-5      I2   Year (last 2 digits, 82=1982).
  6-7      I2   Month (01-12).
    8      A1   Element (D, H, X, Y, Z, or F).
  9-10     I2   Day of month (01-31).
 11-12     A2   Blanks. 
 13-14     A2   Arbitrary.                                             
 15-16     I2   Two blanks or Century digits of the year:              
                 Year 1887 - 18 Century,                              
                 Year 1978 - 19 Century,                               
                 Year 2014 - 20 Century .   
                              ============ Old Format ==============
                               15 column - International quiet or 
                                           disturbed days, Q=1, D=2
                               16 column - Blank for data since 1900,
                                           8 for data before
                              ======================================
 17-20     I4   Tabular base, in degrees for D and             
                in hundreds of nanoTeslas for the intensity elements. 
 21-116  24I4   Twenty-four 4-digit hourly mean values for the day.
                The values are in tenth-minutes for D and in nanoTeslas 
                for the intensity elements. 
                The first hourly mean value represents the mean value 
                between 00:00 UT and 01:00 UT, ..., the 24th value 
                represents the mean between 23:00 UT and 24:00 UT. 
                A missing value is identified by 9999.
117-120    I4   Daily mean. 
                If any of the hourly mean values for the day are missing 
                9999 will appear as the daily mean.
121-122         Record end marker.
                Two chars 'cr'= 13 and 'nl'= 10.

The tabular bases, hourly mean values and daily means are right adjusted 
and signed if negative. 
Negative values are identified with a minus sign either adjacent to the first 
significant digit or in the high-order position of the field.
NOTE: A blank digit will not appear between a (-) sign and the first 
significant digit. For example, a value may appear as -050 or b-50 
but not as -b50 (b=blank).

The 25 values in positions 21-120 will have the range -999 to 9998, 
with 9999 reserved for missing values. 

The records are sorted according to observatory code, year, month, 
element, day ( positions 1-10).

For the intensity elements we have that
      hourly value (nanoTeslas_ = tab.base*100 + tab.value.

For the angles D we have that
     hourly value (Degrees) = Tab.base + tab.value/600.

To avoid a 4-digit negative value in positions 21-116, 
the tabular base will be adjusted for that day; 
for example for D, one degree is subtracted from the base and 600 
units are added to each of the hourly values for the day; 
for the intensity elements, 500 nT are subtracted from the base and 500 nT 
are added to each of the hourly values for the day.
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