Aa Indices.
The aa index is a simple global geomagnetic activity index, with units of 1 nT (nanotesla), which is produced from the K indices from two approximately antipodal observatories. At present these are Hartland observatory in the UK and Canberra observatory in Australia. The main advantage in using aa indices for research purposes is that the time series spans further back (to 1868) than any of the other planetary indices time series.Also, up to date values are produced and made available weekly, giving nearer to real time availability than any other planetary index. In between the weekly updates, BGS calculates estimated aa indices, providing real time "nowcasts" which are updated on an hourly basis. These estimates are clearly marked with the letters "Est". Although calculated by the same method, the aa indices available on this service are not the definitive values. These are published by the International Service for Geomagnetic Indices, CRPE/CNET - CNRS, 4 Avenue de Neptune, F-94107 Saint Maur, Cedex, France.
dataset
http://www.geomag.bgs.ac.uk/data_service/data/magnetic_indices/aaindex.html
function: information
http://data.bgs.ac.uk/id/dataHolding/13480365
eng
OGP
GLOC
Complete time Series. Global: Derived from 2 Antipodal Locations.
geoscientificInformation
publication
2008-06-01
Geomagnetism
revision
2011
NERC_DDC
-180.0000
180.0000
90.0000
-90.0000
creation
1979
WORLD [id=100000]
1868
creation
1868
weekly
The aa indices are derived using data from two nearly antipodal observatories, where magnetograms were available since 1868. For each three hour interval, K indices are measured at the two stations and converted back into amplitude; an individual aa index is the average of the northern and southern values, weighted to account for the small difference in latitude of the two stations, or for the slight changes in the very place of the observatory. The definitive values are published by the International Service for Geomagnetic Indices.
publication
2011
false
See the referenced specification
publication
2010-12-08
false
See http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2010:323:0011:0102:EN:PDF
DELIMITED ASCII - ASCII Year Files or user defined.
The copyright of materials derived from the British Geological Survey's work is vested in the Natural Environment Research Council [NERC]. No part of this work may be reproduced or transmitted in any form or by any means, or stored in a retrieval system of any nature, without the prior permission of the copyright holder, via the BGS Intellectual Property Rights Manager. Use by customers of information provided by the BGS, is at the customer's own risk. In view of the disparate sources of information at BGS's disposal, including such material donated to BGS, that BGS accepts in good faith as being accurate, the Natural Environment Research Council (NERC) gives no warranty, expressed or implied, as to the quality or accuracy of the information supplied, or to the information's suitability for any use. NERC/BGS accepts no liability whatever in respect of loss, damage, injury or other occurence however caused.
British Geological Survey
The Lyell Centre, Research Avenue South
EDINBURGH
EH14 4AP
United Kingdom
0115 936 3142
0115 936 3276
distributor
British Geological Survey
The Lyell Centre, Research Avenue South
EDINBURGH
EH14 4AP
United Kingdom
0115 936 3142
0115 936 3276
originator
British Geological Survey
The Lyell Centre, Research Avenue South
EDINBURGH
EH14 4AP
United Kingdom
0115 936 3142
0115 936 3276
pointOfContact
British Geological Survey
The Lyell Centre, Research Avenue South
EDINBURGH
EH14 4AP
United Kingdom
+44 131 667 1000
pointOfContact
2020-08-04