One-minute Values Format
The logical record length is 400 coded characters containing header
information, blank spaces, and data for one element for one hour.
Each logical record contains header information and data in the
following format:
Columns Format Description
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1-6 I6 Geographic Co-Latitude in 0.001 degree
7-12 I6 East Geographic Longitude in 0.001 degree
13-14 I2 Year (last 2 digits, 82=1982)
15-16 I2 Month (01-12)
17-18 I2 Day (01-31)
19 A1 Component of the field (H,E,Z)
20-21 I2 Hour (00-23)
22-24 A3 Observatory's IAGA 3-letter code
25 A1 Origin of data (D - digital, A - digitized)
26-34 9A1 Blanks
35-40 I6 1-st 1 minute average
41-46 I6 2-nd 1 minute average
... ... .....
388-394 I6 60-th 1 minute average
395-400 I6 Hourly mean value
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Comments:
DATA-1 ... DATA-60 are 1-minute values of the given element for that
hour. H, X, Y, Z, or F are given to the nearest nanoTesla (gamma). D is
given to the nearest tenth-minute of arc (612 = l degree + 01.2 minutes
East). Each value is in a 6-character field.
Missing data spaces are padded with 99999. No alteration of logical
record length is required for different types of computers.
Codes for sources of digital magnetometer data in the WDC system not
only indicate the source organization, but also show whether the data
are average values or point data. For example, 1-minute point values
scaled from analog magnetograms for the production of AE indices are
coded with a "D" because they are "digitized". Typically, digital
1-minute values received by WDCs from organizations operating automatic
magnetic observatory instruments are averages of more frequendy sampled
values, e.g. 10-second point samples. Different organizations process
their higher time resolution observations in different ways. Some may
filter and smooth the observations. Some follow the practice recom-
mended by IAGA of averaging higher time resolution samples from
before and after the minute to obtain a 1-minute value centered
exactly on the minute. Others average values from the beginning of a
given minute to the beginning of the next minute, effectively centering
the mean on the half-minute, in similar fashion to the processing of
1-minute values to obtain hourly means. If the method used to obtain
1-minute average values is important to a user, the WDC will assist in
determining the exact procedure applied.
In general, digital values from national networks are "absolute" and
are tied to baselines determined by are operating institutions. Often
only timely variations data are needed to support special research
campaigns and digital values may be transmitted from regular
observatory sites via satellite relay platforms. Such values are
"flagged" with a "V" as noted below and eventually are replaced by the
standard digital observatory output. Values from special networks such
as the IMS chains are variations only. Attempts are made to check the
absolute output of these instruments but usually no systematic absolute
observations are possible or they are later replaced by adopted
standard observatory digital values.
ORG (data origin codes)
A = Alaskan meridian magnetometer chain (includes Canadian sites) for
lMS
C = Canadian standard observatory network
O = point samples digitized from analog magnetograms
F = France
G = USGS standard observatory network (one station operated by NOAA)
J = Japan
K = US AFGL E-W sub-auroral zone magnetometer chain
R = Western Canadian meridian magnetometer chain operated for IMS
T = Lungping magnetic observatory, Taiwan.
U = E-W mid-latitude magnetometer chain operated for IMS
V = Variations only sent via NOAA GOES satellite relay
W = Eastern Canadian meridian magnetometer chain operated for IMS
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