Javascript is disabled on this browser.
Javascript must be enabled for this website to display and function correctly.

Hourly Means

Information about the observatory hourly mean data

The hourly mean data are from the three UK observatories Eskdalemuir, Lerwick and Hartland. Eskdalemuir data are available from 1911, Lerwick from 1926, Hartland from 1957 and all three are available up to yesterday's date. Values up to the end of 2003 have had final baseline corrections applied and are the definitive absolute hourly mean values. Data from 2004 onwards are all provisional and have not had final baseline corrections applied.

Values of declination (D), horizontal intensity (H) and vertical intensity (Z) are available. The units of declination are degrees. Declination is negative when west of true north. The units of horizontal intensity and vertical intensity are nT. Vertical intensity is positive in the downwards direction.

Values from Abinger (1926-1956) are available on request.

Please note :

  • Although the provisional data can sometimes be missing (denoted by *****) when they are first made available, these gaps are usually filled no later than one week after the end of the month and often earlier than this.
  • The following jumps have been applied to the data to correct for site changes. All the jump values are given as new values minus old values and have the units of minutes of arc for declination and nT for horizontal and vertical intensity.
    1990.0 - Dec. 0; Horiz. 11; Vert. 22
    1994.0 - Dec. 0; Horiz. -8; Vert. -23
    1934.0 - Dec. 0; Horiz. 0; Vert. 144
    1990.0 - Dec. 0; Horiz. 5; Vert. -8
    1996.0 - Dec. 0; Horiz. 0; Vert. 8
    1980.0 - Dec. 0; Horiz. 0; Vert. -6
    1990.0 - Dec. 0; Horiz. -6; Vert. 23

Please enter your name and email address

Observatory code:

From Day of Month : Month (e.g. 6 for June): Year (e.g. 2010):

To Day of Month : Month : Year :

To submit the query, press this button: .

To clear the form, press this button: .