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1991-11-18
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UNDERSTANDING THE DAILY SOLAR GEOPHYSICAL DATA BROADCAST
--------------------------------------------------------
Revision 1.0
The Solar Terrestrial Dispatch (STD) has begun providing a daily
broadcast of solar geophysical indices over the electronic networks. A
sample broadcast message follows below. This sample broadcast data set will
be fully described in this document.
!!BEGIN!! (1.0) S.T.D. Solar Geophysical Data Broadcast for DAY 248, 09/05/91
10.7 FLUX=163.5 90-AVG=206 SSN=204 BKI=5454 3323 BAI=025
BGND-XRAY=B8.6 FLU1=2.7E+05 FLU10=8.3E+03 PKI=5454 4333 PAI=029
BOU-DEV=093,051,073,060,023,030,012,021 DEV-AVG=045 NT SWF=05:079
XRAY-MAX= M4.4 @ 0111UT XRAY-MIN= B8.0 @ 0914UT XRAY-AVG= C2.5
NEUTN-MAX= +003% @ 2250UT NEUTN-MIN= -002% @ 1700UT NEUTN-AVG= +0.5%
PCA-MAX= +0.7DB @ 1425UT PCA-MIN= -0.2DB @ 2325UT PCA-AVG= -0.1DB
BOUTF-MAX=55331NT @ 2250UT BOUTF-MIN=55263NT @ 1649UT BOUTF-AVG=55301NT
GOES7-MAX=E:+113NT@ 0607UT GOES7-MIN=N:-052NT@ 0911UT G7-AVG=+067,+063,+002
GOES6-MAX=P:+101NT@ 1925UT GOES6-MIN=N:-010NT@ 1439UT G6-AVG=+073,+026,+014
FLUXFCST=STD:160,157,155 ; SESC:160,155,150 BAI/PAI-FCST=15,10,10 / 15,15,18
KFCST=3344 5433 2334 4211 27DAY-AP=019,011 27DAY-KP=2333 4333 2233 2322
WARNINGS=*MAJFLR;*PROTON
ALERTS=**MAJFLR:X1.1/2B,N20E29(6857),0523-0555-0641,II=2@0551,IV=3@0602;
**MINFLR:M4.4@0111;**MINFLR:M2.3@0528;**MINFLR:M1.6@1209;
**TENFLR:2200,DUR:N/A
!!END-DATA!!
LINE 01
-------
!!BEGIN!! S.T.D. Solar Geophysical Data Broadcast for DAY 248, 09/05/91
!!BEGIN!! : Signifies the start of the report, for computer-controlled
extraction of the data.
(1.0) : Represents the version number of the data set. The
appropriate software with the same version number must
be used to extract and interpret the data sets.
DAY 248 : The day of the year for the report.
09/05/91 : Equivalent Month/Day/Year of the report.
LINE 02
-------
10.7 FLUX=164.5 90-AVG=206 SSN=204 BKI=5454 3323 BAI=025
10.7 FLUX=164.5 : The 10.7 cm solar radio flux as reported by the
NRC-Dominion Radio Astrophysical Observatory (DRAO) in
Penticton, British Columbia, Canada (formerly produced
by the Algonquin Radio Observatory in Ottawa).
90-AVG=206 : This value represents the 90-day average 10.7 cm solar
radio flux.
SSN=204 : This value is the observed sunspot number as observed by
Mt. Wilson Solar Observatory and reported by NOAA.
BKI=5454 3323 : These digits represent the 8 three-hourly Boulder K-indices
as observed by the Boulder USGS magnetometer. The first
digit represents the observed K-index for the period from
00:00 UT to 02:59 UT. The second digit represents the
observed K-index from 03:00 to 05:59 UT, and so forth.
If data is unavailable, it is replaced with an asterisk.
BAI=025 : This value is the observed 24:00 UT Boulder A-Index for
Boulder, Colorado.
LINE 03
-------
BGND-XRAY=B8.6 FLU1=2.7E+05 FLU10=8.3E+03 PKI=5454 4333 PAI=029
BGND-XRAY=B8.6 : This is the background x-ray flux value as reported by the
Space Environment Laboratories. This value is produced by
observing the background x-ray emissions in the soft-xray
band (1 to 8 Angstroms). Consult the "Glossary of Solar
Terrestrial Terms" as produced by the STD for information
on understanding the x-ray classification scheme. This
document is available for anonymous FTP from the site:
"solar.stanford.edu" in "/pub", or on "nic.funet.fi".
FLU1=2.7E+05 : This value is the observed proton fluence at greater than
1 MeV (million electron volts).
FLU10=8.3E+03 : This is the observed proton fluence at greater than 10 MeV.
PKI=5454 4333 : These digits represent the 8 three-hourly estimated
planetary K-index values for the UT day. The format is
the same as is used for the Boulder K-indices noted above.
PAI=029 : This value represents the estimated planetary A-index value
for the UT day. Occassionally, this value is not available
at the time the data set is compiled. If this is the case,
a preliminary calculation is made to estimate the planetary
A-index value using the planetary K-indices. Although this
will not produce an officially accurate result, the results
calculated in this way are usually accurate to +/- 2 points.
LINE 04
-------
BOU-DEV=093,051,073,060,023,030,012,021 DEV-AVG=045 NT SWF=05:079
BOU-DEV=093,051,073,060,023,030,012,021
These values represent the observed maximum deviation in
the Boulder USGS magnetometer. The values are in nano-
tesla (nT, or reported as "NT" elsewhere in the report).
The first value represents the observed maximum deviation
of the geomagnetic field (using the most disturbed magnetic
component) during the period 00:00 UT to 02:59 UT. In this
example, the maximum deviation observed was 93 nT between
00:00 UT and 02:59 UT. The second value represents the
maximum deviation between 03:00 UT and 05:59 UT. Each of
these values correspond to the observed Boulder K-index
as reported on line 2 of this daily report.
DEV-AVG=045 NT : This value represents the average daily maximum deviation
of the Boulder magnetometer, given in units of nanotesla
(or NT). It is produced by simply averaging the 8
three-hourly maximum deviation values given on this line.
SWF=05:79 : The first value (05) represents the number of possible
episodes of Short Wave Fades (SWFs) observed during the
UT day. Short wave fading is simply a period of time when
the absorption of High Frequency (HF) radio waves increases
which produces a decrease in signal strengths of HF signals
OVER SUNLIT AREAS. In other words, this value represents
the approximate maximum number of times HF signals may have
faded out during the UT day. It is important to note that
SWFs are the strongest over the low and middle latitudes
and are ONLY observed during the daylight hours, preferably
when the sun is higher in the sky.
The second value (79) represents the estimated maximum
number of minutes that solar-flare activity may have
produced observed SWFs. In this example, solar activity
may have produced observed SWFs as many as five times
during the UT day. The estimated maximum number of
minutes that signals may have been degraded was 79.
Please note that these values are estimated maximums.
It is important to remember that most regions of the world
are in darkness for many hours each UT day. During periods
of darkness, SWFs will not be observed. Therefore, these
values are most useful as indicators of the possible
ionospheric disturbances which may have occurred during
the daytime hours. Days with 00 episodes of SWF activity
denote low levels of daytime sporadic HF signal absorption.
LINE 05
-------
XRAY-MAX= M4.4 @ 0111UT XRAY-MIN= B8.0 @ 0914UT XRAY-AVG= C2.5
XRAY-MAX= M4.4 @ 0111UT
This value represents the maximum observed X-ray level
during the UT day, as well as the time of its occurrence.
In this example, x-rays during this UT day peaked at a
class M4.4 level at 01:11 UT.
XRAY-MIN= B8.0 @0914UT
This section of the report represents the minimum observed
x-ray level during the UT day. Same format as the maximum.
XRAY-AVG= C2.5 : This value represents the average x-ray flux observed
during the UT day. This value is determined by averaging
all of the 1-minute x-ray values during the UT day. This
average value might not always be determined by a full set
of one-minute daily values. If data from the GOES
spacecraft supplying this information is temporarily
halted, this value will be calculated from those daily
one-minute values which are received. It is therefore
possible, (although extremely unlikely) that this average
value may be produced from only one or two one-minute flux
measurements.
It is important to distinguish the difference between the
background x-ray flux and the average x-ray flux. The
average x-ray flux is the actual numerical average of all
daily x-ray bursts (including all x-ray flares). The
background x-ray flux is the lowest stable x-ray level
observed during the day which is not associated with x-ray
bursts. The x-ray average will therefore almost always be
higher than the background x-ray flux. In this example,
the average x-ray flux is a fair bit higher than the
background level, possibly due to a number of x-ray bursts
which occurred during the UT day.
LINE 06
-------
NEUTN-MAX= +003% @ 2250UT NEUTN-MIN= -002% @ 1700UT NEUTN-AVG= +0.5%
NEUTN-MAX= +003% @ 2250UT
This is the maximum observed neutron monitor count as
observed by the Thule neutron monitor. It indicates a
maximum observed value of 3% which occurred at 22:50 UT.
Significant maximums of greater than 10% may be related to
Ground Level Events (GLEs) which are associated with near-
relativistic particle bombardments from major solar flares.
These neutron monitor values are determined by examining
the 5-minute averages of the neutron monitor count rates.
NEUTN-MIN= -002% @ 1700 UT
This is the observed minimum neutron monitor count as
measured by the Thule neutron monitor. Values below
-5% may be related to Forbush decreases (FDs) which are
most often associated with strong geomagnetic disturbances.
NEUTN-AVG= +0.5%: This value represents the average neutron monitor count as
observed by the Thule neutron monitor. Average values
below -5.0% are associated with Forbush decreases.
LINE 07
-------
PCA-MAX= +0.7DB @ 1425UT PCA-MIN= -0.2DB @ 2325UT PCA-AVG= -0.1DB
PCA-MAX= +0.7DB @ 1425UT
This section shows the maximum Polar Cap Absorption (PCA)
level observed during the UT day by the Thule T30A
Riometer. Positive values indicate elevated levels of
ionospheric absorption over the polar regions. As a
result, positive values (particularly in excess of about
1.0 to 2.0 dB) are sufficient to cause notable attenuation
of HF signals over or near the polar regions. Values
larger than 3.0 to 4.0 dB may cause heavy to complete
absorption of HF radio signals over the polar and possibly
some high latitude signal paths. Riometer values less than
or equal to 0.0 dB are associated with negligable
absorption levels over the polar regions. Note that small
levels of absorption (of only a few tenths of a dB) may be
sufficient to cause errors in navigational signals such as
OMEGA navigational signals traversing the polar regions.
PCA-MIN= -0.2DB @ 2325UT
This is the minimum PCA level observed during the UT day.
PCA-AVG= -0.1DB : This is the average PCA level observed during the UT day
and is calculated by averaging the 5-minute averaged
riometer measurements during the UT day.
LINE 08
-------
BOUTF-MAX=55331NT @ 2250UT BOUTF-MIN=55263NT @ 1649UT BOUTF-AVG=55301NT
BOUTF-MAX=55331NT @ 2250UT
This is the maximum observed value of the Total magnetic
Field (TF). The total field value is calculated by using
all three orthogonal components of the geomagnetic field.
These values are valid for Boulder, Colorado. The field
values are in units of nanotesla (NT). The time of the
maximum is also indicated.
BOUTF-MIN=55263NT @ 1649UT
This is the minimum observed value of the total field at
Boulder, Colorado.
BOUTF-AVG=55301NT
This is the daily average of the total magnetic field
strength as observed at Boulder for the UT day.
LINES 09 & 10
-------------
GOES7-MAX=E:+113NT@ 0607UT GOES7-MIN=N:-052NT@ 0911UT G7-AVG=+067,+063,+002
GOES6-MAX=P:+101NT@ 1925UT GOES6-MIN=N:-010NT@ 1439UT G6-AVG=+073,+026,+014
These two lines report the maximum, minimum and observed
average values of the geomagnetic field at geosynchronous
altitudes as observed by the GOES-6 and GOES-7 spacecraft.
GOES-7 is the primary spacecraft and is therefore reported
first.
The first capital letter following the "GOES7-MAX="
statement indicates which component of the magnetic field
experienced the maximum value observed during the UT day.
There are three possible letters which may be used here,
representing one of the three possible magnetic components:
P = The component parallel to the Earths rotation
axis. Positive values are northward. Negative
values are southward.
E = This is the Earthward component. Positive
values represent a downwardly directed field
(ex. toward the Earth or Earthward).
N = This component is perpendicular to the other
two. Positive values represent a westwardly
directed field. Negative values are eastward.
The figure following the "P:", "E:", or "N:" is the
observed magnitude of that component, followed by the time
that the value was observed. In this example, the GOES-7
spacecraft Earthward magnetic component was the observed
maximum component during the UT day. The magnitude of this
maximum Earthward component was +113 nanoteslas. This
represents a downwardly directed magnetic field with a
strength of 113 nT. GOES-7 observed this max at 06:07 UT.
This same format is followed for the minimum values
observed on GOES-7 as well as for the values on GOES-6.
G7-AVG=+067,+063,+002
This line reports the average geomagnetic field strengths
for the three magnetic components of the GOES-7 spacecraft.
The first value will ALWAYS represent the Parallel magnetic
component. The second value will ALWAYS represent the
Earthward magnetic component. And the last value will
ALWAYS represent the Perpendicular component. So in this
example, the average daily magnetic field strength for the
parallel component was +67 nT. The Earthward component had
an average field strength value of +63 nT while the
perpendicular component had an average value of +2 nT.
This same format is followed for the average values of the
GOES-6 secondary spacecraft.
LINE 11
-------
FLUXFCST=STD:160,157,155 ; SESC:160,155,150 BAI/PAI-FCST=15,10,10 / 15,15,18
FLUXFCST=STD:160,157,155 ; SESC:160,155,150
The first three values represent the 72-hour forecast
10.7 cm solar radio flux values as produced by the Solar
Terrestrial Dispatch (STD). The second group of three
values are the 72-hour 10.7 cm solar radio flux forecast
values as issued by the Space Environment Services Center.
If either of these two forecasts are unavailable, "N/A"
will be used in place of the digits.
BAI/PAI-FCST=15,10,10 / 15,15,18
The first group of three values represent the 72-hour
forecast Boulder A-Index (BAI) values as issued by the
Space Environment Services Center. The second group of
three digits represent the 72-hour forecast Planetary
A-Index values (PAI) as issued by the United States Air
Force (USAF) Global Weather Central.
LINE 12
-------
KFCST=3344 5433 2334 4211 27DAY-AP=019,011 27DAY-KP=2333 4333 2233 2322
KFCST=3344 5433 2334 4211
These digits represent the 48-hour K-index fourcasts as
released by the Space Environment Services Center. The
first value represents the forecast K-index value for 00:00
to 02:59 UT. The second value represents the forecast K-
index value from 03:00 UT to 05:59 UT, etc. The sixteen
digits define the expected K-indices for the next 48 hours.
27DAY-AP=019,011: These values are the historical estimated planetary A-index
values that were observed 27 days ago (approximately one
solar rotation). The first value represents the observed
estimated planetary A-index value 27 days ago. The second
value represents the value observed 26 days ago. These
two values may help serve as a guide to the possible
intensity of recurrent geomagnetic phenomena.
27DAY-KP=2333 4333 2233 2322
These digits are the estimated planetary K-index values
that were observed 27 days ago. The first group of eight
digits (2333 4333) represent the three-hourly planetary
K-indices that were observed 27 days ago. The second
group of eight digits (2233 2322) represent the K-index
values that were observed 26 days ago.
LINE 13, 14...
--------------
WARNINGS=*MAJFLR;*PROTON
ALERTS=**MAJFLR:X1.1/2B,N20E29(6857),0523-0555-0641,II=2@0551,IV=3@0602;
**MINFLR:M4.4@0111;**MINFLR:M2.3@0528;**MINFLR:M1.6@1209;
**TENFLR:2200,DUR:N/A
These lines summarize the Warnings and Alerts which are active at
the end of the UT day. Each warning category is prepended with a SINGLE
asterisk. Each alert category is prepended with DOUBLE asterisks. The end
of each warning and alert is appended with a semicolon if more warnings
follow. If no warnings follow, a carriage return concludes the category.
Warnings and alerts may span several lines. These WARNINGS are valid:
*MAJFLR = Potential Major Flare Warning
*PROTON = Potential Satellite Proton Event Warning
*PROTFLR = Potential Proton Flare Warning
*GSTRM = Potential Geomagnetic Storm Warning
*MSTRM = Potential Minor Geomagnetic Storm
*JSTRM = Potential Major-Severe Geomagnetic Storm
*AURMIDWCH= Middle Latitude Auroral Activity WATCH
*AURMIDWRN= Middle Latitude Auroral Activity WARNING
*AURLOWWCH= Low Latitude Auroral Activity WATCH
*AURLOWWRN= Low Latitude Auroral Activity WARNING
*PCA = Potential Polar Cap Absorption Event Warning
The following ALERTS are valid:
**MAJFLR = Major Solar Flare Alert
**MINFLR = Minor Solar Flare Alert
**MINSTRM = Minor Geomagnetic Storm Alert
**MAJSTRM = Major Geomagnetic Storm Alert
**SVRSTRM = Severe Geomagnetic Storm Alert
**PCA = Polar Cap Absorption Event Alert
**PCAENH = Polar Cap Absorption Enhancement Alert
**PROTN10 = Satellite Proton Event Alert at > 10 MeV
**PROTN100= Satellite Proton Event Alert at > 100 MeV
**PROTNENH= Satellite Proton Enhancment Alert at > 10 MeV
**MAGSI = Magnetic Sudden Impulse Alert
**245STRM = 245 MHz Radio Noise Storm Alert
**TENFLR = Tenflare Alert
**SWEEP = Sweep Frequency Event Alert
**FORBUSH = Forbush Decrease Event Alert
**GLE = Ground Level Event Alert
Each of the alerts may be followed by a colon and very terse descriptive
text describing parameters of the event. For example, the alert section
within this example reads:
ALERTS=**MAJFLR:X1.1/2B,N20E29(6857),0523-0555-0641,II=2@0551,IV=3@0602;
**MINFLR:M4.4@0111;**MINFLR:M2.3@0528;**MINFLR:M1.6@1209;
**TENFLR:2200,DUR:N/A
This line consists of FIVE alerts (each set of double asterisks denotes the
start of a new alert): One major flare alert, three Minor Solar Flare alerts
and a Tenflare alert. In this example, the major flare was a class X1.1/2B
event located at N20E29 within Region 6857. It began at 05:23 UT, peaked at
05:55 UT and ended at 06:41 UT and was associated with a Type II sweep
(importance 2) at 05:51 UT and a Type IV sweep (importance 3) at 06:02 UT.
If a tenflare would have been associated with this event, it would have been
treated as a separate alert with a time corresponding to the time of the
major flare. In this ficticious example, no tenflare was observed.
The first minor solar flare was a class M4.4 which occurred at 01:11 UT.
The second was a class M2.3 at 05:28 UT. The third was a class M1.6 at 12:09
UT and the Tenflare was observed at 22:00 UT. The DURation of the tenflare
was unknown (not available) at the time the report was compiled.
Notice that the last alert is not followed by a semicolon. This marks
the end of the alert section.
LAST LINE
---------
!!END-DATA!! : The last line of the daily report will ALWAYS contain this
final statement, which signifies the end of the data set.
FINAL NOTES
-----------
Additional warnings and alerts may be added to those mentioned here.
The format of this data set may also change over time. Data may be
added or deleted from the existing data set. However, for the most part, the
structure will remain the same. Comments may be appended to the message
following the dataset (ex. following the !!END-DATA!! marker), although this
will not be a common practice. The length of the daily data set should be
approximately 15-16 lines, but may vary slightly depending on the number of
warnings and alerts that are active during each day.
This is the same data set that is sent to other organizations and
institutions for research or professional purposes. Individuals or
organizations with a need to directly receive this data through email should
send requests for placement on the mailing list to: Oler@Hg.Uleth.CA, or to:
COler@Solar.Stanford.Edu. Only those with a professional need, or those who
receive the data too late to be of value, are encouraged to request direct
access to the mailing list.
There may be infrequent days when no data sets are broadcast. This may
be due to local computer problems, or perhaps possible problems with sites
forwarding the data sets through the nets. In most circumstances, the data
sets should arrive daily. They are usually released once a day, sometime
after approximately 02:00 to 03:00 UT. This time lag into the new UT day is
required so that all of the data associated with the previous UT day may be
collected and processed for inclusion with the daily data set.
** End of Daily Solar Geophysical Broadcast Description **
