BRITISH GEOLOGICAL SURVEY Port Stanley Observatory Monthly Magnetic Bulletin February 2008 08/02/PS
Jason Islands cass Island Cara West Falkland SaundersKeppel Island Island Kin g George Bay Mount Port Salavador Adam Queen Charlotte Bay Mount Osborne Berkley 700m Sapper Hill Sound 705m Weddell Darwin Stanley Goose Island kland Sound Choiseul Fal Green Sound
Port Stephens
Bay of East Falkland Harbours Eagl e Passage Falkland Islands
©Crown copyright; Ordnance Survey PORT STANLEY OBSERVATORY MAGNETIC DATA
1. Introduction perpendicular to these, and measures variations, which are proportional to the changes in declination (D). Port Stanley Observatory was installed by BGS with Measurements are made at a rate of 1 Hz. financial support from a consortium of oil companies and became operational in February 1994. In addition to the fluxgate sensors there is a proton precession magnetometer making measurements of the This bulletin is published to meet the needs of users of absolute total field intensity (F) at a rate of 0.1Hz. geomagnetic data. Magnetic observatory data is presented as a series of plots of one-minute, hourly The raw unfiltered data are retrieved automatically via and daily values, followed by a tabulation of monthly Internet connections to the BGS office in Edinburgh in values. The operation of the observatory and near real-time. The fluxgate data are filtered to presentation of data are described in the rest of this produce one-minute values using a 61-point cosine section. filter whilst the total field intensity samples are filtered using a 7-point cosine filter. Enquiries about the data should be addressed to: 3.2 Absolute Observations National Geomagnetic Service The GDAS fluxgate magnetometers accurately British Geological Survey measure variations in the components of the Murchison House, West Mains Road geomagnetic field, but not the absolute magnitudes. Edinburgh EH9 3LA Two sets of absolute measurements of the field are Scotland, UK made manually once per week. A fluxgate sensor mounted on a theodolite is used to determine D and Tel: +44 (0) 131 667 1000 inclination (I); the GDAS PPM measurements, with a Fax: +44 (0) 131 650 0265 site difference correction applied, are used for F. The E-mail: [email protected] absolute observations are used in conjunction with the Internet: www.geomag.bgs.ac.uk GDAS variometer measurements to produce a continuous record of the absolute values of the 2. Position geomagnetic field elements as if they had been measured at the observatory reference pillar. Port Stanley Observatory, one of the geomagnetic observatories maintained and operated by the British 4. Data Presentation Geological Survey (BGS), is situated on a site at The data presented in the bulletin are in the form of Sapper Hill near Port Stanley in the Falkland Islands. plots and tabulations described in the following The observatory co-ordinates are: sections.
Geographic: 51° 42.2′ S 302° 06.6′ E 4.1 Absolute Observations Geomagnetic: 41° 41.1′ S 11° 27.2′ E The absolute observation measurements made during Height above mean sea level: 135 m the month are tabulated. Also included are the corresponding baseline values, which are the The geomagnetic co-ordinates are calculated using the differences between the absolute measurements and 10th generation International Geomagnetic Reference the variometer measurements of D, H and Z (in the Field at epoch 2008.5. sense absolute−variometer). These are also plotted (markers) along with the derived preliminary daily 3. The Observatory Operation baseline values (line) throughout the year. Daily mean differences between the measured absolute F and the 3.1 GDAS F computed from the baseline corrected H and Z The observatory operates under the control of the values are plotted in the fourth panel (in the sense Geomagnetic Data Acquisition System (GDAS), measured−derived). The bottom panel shows the developed by BGS, which was installed in August daily mean temperature in the fluxgate chamber. 2002. The system operates under the control of data acquisition software running on QNX computers, 4.2 Summary magnetograms which control the data logging and communications. Small-scale magnetograms are plotted which allow the month's data to be viewed at a glance. They are plotted There are two sets of sensors used for making 16 days a page and show the variations in D, H and Z. magnetic measurements. A triaxial linear-core fluxgate The scales are shown on the right-hand side of the magnetometer, manufactured by the Danish page. On disturbed days the scales are multiplied by a Meteorological Institute, is used to measure the factor, which is indicated above the panel for that day. variations in the horizontal (H) and vertical (Z) The variations are centred on the monthly mean value, components of the field. The third sensor is oriented shown on the left side of the page. 4.3 Magnetograms The daily magnetograms are plotted using one-minute values of D, H and Z from the fluxgate sensors, with any gaps filled using back-up data. The magnetograms are plotted to a variable scale; scale bars are shown to the right of each plot. The absolute level (the monthly mean value) is indicated on the left side of the plots.
4.4 Hourly Mean Value Plots Hourly mean values of D, H and Z for the past 12 months are plotted in 27-day segments corresponding to the Bartels solar rotation number. Magnetic disturbances associated with active regions on the surface of the Sun may recur after 27 days: the same is true for geomagnetically quiet intervals. Plotting the data in this way highlights this recurrence, and also illustrates seasonal and diurnal variations throughout the year.
4.5 Daily and Monthly Mean Values Daily mean values of D, H, Z and F are plotted throughout the year. In addition, a table of monthly mean values of all the geomagnetic elements is provided. These values depend on accurate specification of the fluxgate sensor baselines. This data is provisional. It is anticipated that provisional values will not be altered by more than a few nT or tenths of arcminutes before being made definitive.
© NERC 2008
PORT STANLEY OBSERVATORY
ABSOLUTE OBSERVATIONS
DECLINATION INCLINATION Total H H Z Z Day Time Absolute Baseline Time Inclination Field Date Absolute Baseline Absolute Baseline Observer Number (UT) (º) (º) (UT) (º) Intensity (nT) (nT) (nT) (nT) (nT)
09-Feb-08 40 16:12 3.6504 3.5850 16:18 -49.2448 28883.9 18856.3 18874.1 -21879.7 -21779.1 NB
09-Feb-08 40 16:24 3.6702 3.5933 16:29 -49.2282 28884.1 18862.7 18878.6 -21874.4 -21775.2 NB
24-Feb-08 55 19:12 3.6439 3.5700 19:19 -49.2203 28886.0 18867.0 18866.0 -21873.3 -21787.7 NB
24-Feb-08 55 19:27 3.6443 3.5717 19:36 -49.2142 28887.1 18870.0 18866.0 -21872.1 -21787.6 NB
Falkland Island 2008 Declination : Absolute - Variometer (markers) and Baseline Applied (line)
215.6 5min
Horizontal Intensity : Absolute - Variometer (markers) and Baseline Applied (line)
18867 20nT
Vertical Intensity : Absolute - Variometer (markers) and Baseline Applied (line)
-21782 20nT
Total Intensity : Absolute (Proton F) - Baseline Adjusted Variometer (derived F)
25.0 20nT
Temperature Inside Variometer Hut
22.6 20 C
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Falkland Islands February 2008 1 2 3 4
o D 3.57 0.50
H 18861
Z -21875
5 6 7 8
D 3.57
H 18861 150 nT
Z -21875
9 10 11 12
D 3.57
H 18861
Z -21875 150 nT
13 14 15 16
D 3.57
H 18861
Z -21875
6 12 18 24 6 12 18 24 6 12 18 24 6 12 18 24 17 18 19 20
o D 3.57 0.50
H 18861
Z -21875
21 22 23 24
D 3.57
H 18861 150 nT
Z -21875
25 26 27 28
D 3.57
H 18861
Z -21875 150 nT
29 6 12 18 24 6 12 18 24 6 12 18 24 UT UT UT D 3.57
H 18861
Z -21875
6 12 18 24 Falkland Islands February 2008 Date: 01-02-2008Falkland Islands Day number: 032 Declination in degrees east
3.57 15min
Horizontal Intensity in nT
18861 30nT
Vertical Intensity in nT
-21875 30nT
0 3 6 9 12 15 18 21 24
Date: 02-02-2008 Day number: 033 Declination in degrees east
3.57 15min
Horizontal Intensity in nT
18861 30nT
Vertical Intensity in nT
-21875 20nT
0 3 6 9 12 15 18 21 24 Hour (UT) Date: 03-02-2008Falkland Islands Day number: 034 Declination in degrees east
3.57 15min
Horizontal Intensity in nT
18861 20nT
Vertical Intensity in nT
-21875 20nT
0 3 6 9 12 15 18 21 24
Date: 04-02-2008 Day number: 035 Declination in degrees east
3.57 15min
Horizontal Intensity in nT
18861 20nT
Vertical Intensity in nT
-21875 10nT
0 3 6 9 12 15 18 21 24 Hour (UT) Date: 05-02-2008Falkland Islands Day number: 036 Declination in degrees east
3.57 15min
Horizontal Intensity in nT
18861 10nT
Vertical Intensity in nT
-21875 10nT
0 3 6 9 12 15 18 21 24
Date: 06-02-2008 Day number: 037 Declination in degrees east
3.57 15min
Horizontal Intensity in nT
18861 20nT
Vertical Intensity in nT
-21875 10nT
0 3 6 9 12 15 18 21 24 Hour (UT) Date: 07-02-2008Falkland Islands Day number: 038 Declination in degrees east
3.57 15min
Horizontal Intensity in nT
18861 20nT
Vertical Intensity in nT
-21875 20nT
0 3 6 9 12 15 18 21 24
Date: 08-02-2008 Day number: 039 Declination in degrees east
3.57 15min
Horizontal Intensity in nT
18861 20nT
Vertical Intensity in nT
-21875 10nT
0 3 6 9 12 15 18 21 24 Hour (UT) Date: 09-02-2008Falkland Islands Day number: 040 Declination in degrees east
3.57 15min
Horizontal Intensity in nT
18861 20nT
Vertical Intensity in nT
-21875 20nT
0 3 6 9 12 15 18 21 24
Date: 10-02-2008 Day number: 041 Declination in degrees east
3.57 15min
Horizontal Intensity in nT
18861 30nT
Vertical Intensity in nT
-21875 20nT
0 3 6 9 12 15 18 21 24 Hour (UT) Date: 11-02-2008Falkland Islands Day number: 042 Declination in degrees east
3.57 15min
Horizontal Intensity in nT
18861 20nT
Vertical Intensity in nT
-21875 20nT
0 3 6 9 12 15 18 21 24
Date: 12-02-2008 Day number: 043 Declination in degrees east
3.57 15min
Horizontal Intensity in nT
18861 20nT
Vertical Intensity in nT
-21875 20nT
0 3 6 9 12 15 18 21 24 Hour (UT) Date: 13-02-2008Falkland Islands Day number: 044 Declination in degrees east
3.57 15min
Horizontal Intensity in nT
18861 30nT
Vertical Intensity in nT
-21875 20nT
0 3 6 9 12 15 18 21 24
Date: 14-02-2008 Day number: 045 Declination in degrees east
3.57 15min
Horizontal Intensity in nT
18861 30nT
Vertical Intensity in nT
-21875 20nT
0 3 6 9 12 15 18 21 24 Hour (UT) Date: 15-02-2008Falkland Islands Day number: 046 Declination in degrees east
3.57 15min
Horizontal Intensity in nT
18861 20nT
Vertical Intensity in nT
-21875 10nT
0 3 6 9 12 15 18 21 24
Date: 16-02-2008 Day number: 047 Declination in degrees east
3.57 15min
Horizontal Intensity in nT
18861 20nT
Vertical Intensity in nT
-21875 10nT
0 3 6 9 12 15 18 21 24 Hour (UT) Date: 17-02-2008Falkland Islands Day number: 048 Declination in degrees east
3.57 15min
Horizontal Intensity in nT
18861 10nT
Vertical Intensity in nT
-21875 20nT
0 3 6 9 12 15 18 21 24
Date: 18-02-2008 Day number: 049 Declination in degrees east
3.57 15min
Horizontal Intensity in nT
18861 20nT
Vertical Intensity in nT
-21875 10nT
0 3 6 9 12 15 18 21 24 Hour (UT) Date: 19-02-2008Falkland Islands Day number: 050 Declination in degrees east
3.57 15min
Horizontal Intensity in nT
18861 20nT
Vertical Intensity in nT
-21875 10nT
0 3 6 9 12 15 18 21 24
Date: 20-02-2008 Day number: 051 Declination in degrees east
3.57 15min
Horizontal Intensity in nT
18861 20nT
Vertical Intensity in nT
-21875 20nT
0 3 6 9 12 15 18 21 24 Hour (UT) Date: 21-02-2008Falkland Islands Day number: 052 Declination in degrees east
3.57 15min
Horizontal Intensity in nT
18861 20nT
Vertical Intensity in nT
-21875 20nT
0 3 6 9 12 15 18 21 24
Date: 22-02-2008 Day number: 053 Declination in degrees east
3.57 15min
Horizontal Intensity in nT
18861 20nT
Vertical Intensity in nT
-21875 10nT
0 3 6 9 12 15 18 21 24 Hour (UT) Date: 23-02-2008Falkland Islands Day number: 054 Declination in degrees east
3.57 15min
Horizontal Intensity in nT
18861 20nT
Vertical Intensity in nT
-21875 10nT
0 3 6 9 12 15 18 21 24
Date: 24-02-2008 Day number: 055 Declination in degrees east
3.57 15min
Horizontal Intensity in nT
18861 20nT
Vertical Intensity in nT
-21875 10nT
0 3 6 9 12 15 18 21 24 Hour (UT) Date: 25-02-2008Falkland Islands Day number: 056 Declination in degrees east
3.57 15min
Horizontal Intensity in nT
18861 20nT
Vertical Intensity in nT
-21875 10nT
0 3 6 9 12 15 18 21 24
Date: 26-02-2008 Day number: 057 Declination in degrees east
3.57 15min
Horizontal Intensity in nT
18861 20nT
Vertical Intensity in nT
-21875 10nT
0 3 6 9 12 15 18 21 24 Hour (UT) Date: 27-02-2008Falkland Islands Day number: 058 Declination in degrees east
3.57 15min
Horizontal Intensity in nT
18861 30nT
Vertical Intensity in nT
-21875 20nT
0 3 6 9 12 15 18 21 24
Date: 28-02-2008 Day number: 059 Declination in degrees east
3.57 15min
Horizontal Intensity in nT
18861 40nT
Vertical Intensity in nT
-21875 20nT
0 3 6 9 12 15 18 21 24 Hour (UT) Date: 29-02-2008Falkland Islands Day number: 060 Declination in degrees east
3.57 15min
Horizontal Intensity in nT
18861 40nT
Vertical Intensity in nT
-21875 30nT
0 3 6 9 12 15 18 21 24 Falkland Islands Observatory: Declination (degrees)
3.75 Rotn
3.45 2369 Mar07
2370 Apr
2371 May
2372 Jun
2373 Jul
2374 Aug
2375 Sep
2376
2377 Oct
2378 Nov
2379 Dec
2380 Jan08
2381 Feb
2382
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 Hourly Mean Values Plotted By Bartels Solar Rotation Number Falkland Islands Observatory: Horizontal Intensity (nT)
18950 Rotn
18835 2369 Mar07
2370 Apr
2371 May
2372 Jun
2373 Jul
2374 Aug
2375 Sep
2376
2377 Oct
2378 Nov
2379 Dec
2380 Jan08
2381 Feb
2382
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 Hourly Mean Values Plotted By Bartels Solar Rotation Number Falkland Islands Observatory: Vertical Intensity (nT)
-21855 Rotn
-21930 2369 Mar07
2370 Apr
2371 May
2372 Jun
2373 Jul
2374 Aug
2375 Sep
2376
2377 Oct
2378 Nov
2379 Dec
2380 Jan08
2381 Feb
2382
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 Hourly Mean Values Plotted By Bartels Solar Rotation Number Falklands Is Observatory 2008 Daily Mean Declination (deg)
214.5 10min
Daily Mean Horizontal Intensity (nT)
18868 50nT
Daily Mean Vertical Intensity (nT)
-21876 50nT
Daily Mean Total Intensity (nT)
28889 50nT
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Monthly Mean Values for Port Stanley Observatory 2008
Month D H I X Y Z F
January 3° 34.6´ 18875 nT -49° 12.7´ 18838 nT 1178 nT -21876 nT 28893 nT February 3° 34.3´ 18861 nT -49° 13.9´ 18824 nT 1175 nT -21875 nT 28884 nT
Note i. The values shown here are provisional.