HOURLY VALUES
COLUMNS FMT DESCRIPTION
1-3 A3 OBSERVATORY 3-LETTER CODE, left adjused
4-5 I2 YEAR (last 2 digits, 82 = 1982)
6-7 I2 MONTH (01-12)
8 A1 ELEMENT(D,H,X,Y,Z,or F)
9-10 I2 DAY OF MONTH (01-31)
11-12 A2 Blanks
13-14 A2 Arbitrary
15 A1 INTERNATIONAL QUIET or DISTURBED DAYS,
Q=1,D=2
16 I1 Blank for data since 1900,8 for data before
17-20 I4 Tabular base, in degrees for D and I, hundreds of nanoTeslas
(gammas) for the intensity elements. The bases are right adjusted
and signed if negative. Negative values are identified with a
minus sign either adjacent to the first significant digit or in
the high-order position of the field (position 17). NOTE: A blank
digit will not appear between a (-) sign and the first significant
digit. For example, a base may appear as -050 or b-50 but not as
-b50(b=blank).
21-116 24I4 Twenty-four 4-digit Hourly Values for the day. The values are in
tenth-minutes for D and in nanoTeslas (gammas) for the intensity
elements. The first hourly value represents the mean value between
00:00 UT and 01:00 UT, ..., the 24th value represents the mean
between 23:00 UT and 24:00 UT. Rules for negative values are
the same as those described for tabular bases. A missing value is
identified by 9999.
117-120 I4 Daily Mean. Rules for negative values are the same as those
described for tabular bases. If any of the hourly mean values for
the day are missing 9999 will appear as the daily mean.
The 25 values in positions 21-120 will have the range -999 to 9998, with 9999
reserved for missing values. To avoid a 4-digit negative value in positions
21-116, the tabular base will be adjusted for that day; for example for D, one
degree is subtracted from the base and 600 units are added to each of the
hourly values for the day - for the intensity elements, 500 nT are subtracted
from the base and 500 nT are added to each of the hourly values for the day.
Each tape block contains 20 records (2400 characters). A standard inter-record
gap appears between tape blocks. When necessary, all nines are used as padding
to complete the last block of data. Two or more tape marks follow the last
block of data. The records are sorted according to observatory code, year,
month, element, day (positions 1-10).
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:
*********************************************************************
Characters: 1 - 6 Geographic Co-Latitude in 0.001 degree
7 - 12 East Geographic Longitude in 0.001 degree
13 - 14 Year (98)
15 - 16 Month (01 - 12)
17 - 18 Day (01 - 31)
19 Component of the field (H,E,Z)
20 - 21 Hour (00 - 23)
22 - 24 Observatory's IAGA 3-letter code
25 Origin of data (D - digital, A - digitized)
26 - 34 Future Use (NOT USED HERE)
35 - 40 1-st 1 minute average
41 - 46 2-nd 1 minute average
... ... .....
388 - 394 60-th 1 minute average
394 - 400 Hourly mean value
FORTRAN format statement would look like:
format (2i6,2i2,a1,i2,a3,a1,9a1,61(i6))
*********************************************************************
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