European Repeat Station Workshop Bucharest May 2007

Recent changes at World Data Centre for Geomagnetism (Edinburgh)

Susan Macmillan, Tom Shanahan and Sarah Reay

European Repeat Station Workshop Bucharest May 2007

The World Data Centres

• started 50 years ago by ICSU as part of IGY to ensure open access to global data for academic use and long-term stewardship for future scientists

• originally focussed on physical sciences e.g. solar-terrestrial, geomagnetism, oceanography, meteorology

• centres today more broadly environmental e.g. soils, climate, biodiversity, ecology

• WDC Conference last week in Bremen, Germany. Discussions on: relationships with other umbrella organisations e.g. GEOSS, FAGS metadata standards – more for geospatial data and not ideal for time

series data e.g. ISO data publication and need for persistent identifiers e.g. DOI

assignation

European Repeat Station Workshop Bucharest May 2007

New Journal, to be published by Copernicus Publications

credit: H. Pfeiffenberger/A. Richter

European Repeat Station Workshop Bucharest May 2007

Recent changes at WDC (Edinburgh)

• Operation of online Geomagnetic Data Master Catalogue for observatory minute and hourly values passed from DMI to BGS in May 2007

• Address is www.wdc.bgs.ac.uk

• See poster!

European Repeat Station Workshop Bucharest May 2007

Data holdings in WDC Edinburgh

0

25

50

75

100

125

150

175

200

1810 1830 1850 1870 1890 1910 1930 1950 1970 1990 2010Year

Nu

mb

er

of

ob

se

rva

tori

es

Minute means

Hourly means

Annual means

European Repeat Station Workshop Bucharest May 2007

Repeat data collectionwhat we do....

• Letters sent every year to organisations operating observatories requesting repeat station data (this misses out countries which have repeat station networks but no observatories)

• Data received in wide variety of formats and reformatted into common format• Data compared with previous data and IGRF for gross errors

European Repeat Station Workshop Bucharest May 2007

Global magnetic survey data holdings 1900 onwards

Feb 2003 Mar 2005 May 2007

One-off land vector data 126172

Aeromagnetic vector and scalar data 13512

Marine vector data 13087

Marine scalar data 24515

Repeat vector data 20589 20790 20937

Total 197875

European Repeat Station Workshop Bucharest May 2007

Number of repeat vector data in world and in Europe

TOTAL = 20937

European Repeat Station Workshop Bucharest May 2007

Locations of repeat vector data 1975-2007

TOTAL = 8407 (8260)

European Repeat Station Workshop Bucharest May 2007

Locations of repeat vector data added since Mar 2005

European Repeat Station Workshop Bucharest May 2007

These stations provide data for global modellinge.g. the new GUFM model by Jackson and Finlay where

differences are used to remove the crustal bias

Issue 1: some stations have reoccupation intervals of up to 15

years (and more!)

European Repeat Station Workshop Bucharest May 2007

Issue 2: number of repeat station SV estimates/year not even in time

European Repeat Station Workshop Bucharest May 2007credit: Chris Finlay

Issue 3: difficult to assign meaningful errors...but still useful!

European Repeat Station Workshop Bucharest May 2007

Locations of repeat vector data in Europe 1975 - 2007

TOTAL = 4244 (4125)

European Repeat Station Workshop Bucharest May 2007

Example of data available from www.geomag.bgs.ac.uk/gifs/surveydata.html

260 external requests/year

European Repeat Station Workshop Bucharest May 2007

Summary

• WDC Edinburgh actively maintaining Geomagnetic Data Master Catalogue for observatory data and global magnetic survey dataset

• Several global models incorporate repeat station data• However, main purpose of collecting repeat station

data should remain the derivation of regional models• Would welcome help checking that data held are

complete and correct • Data reformatted by Gerald Duma’s RS-ENTER

particularly welcome!