
           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!!  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  28DAY-AP=019,011   28DAY-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.

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
                  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  28DAY-AP=019,011   28DAY-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.

28DAY-AP=019,011: These values are the historical estimated planetary A-index
                  values that were observed 28 days ago (approximately one
                  solar rotation).  The first value represents the observed
                  estimated planetary A-index value 28 days ago.  The second
                  value represents the value observed 27 days ago.  These
                  two values may help serve as a guide to the possible
                  intensity of recurrent geomagnetic phenomena.

28DAY-KP=2333 4333 2233 2322
                  These digits are the estimated planetary K-index values
                  that were observed 28 days ago.  The first group of eight
                  digits (2333 4333) represent the three-hourly planetary
                  K-indices that were observed 28 days ago.  The second
                  group of eight digits (2233 2322) represent the K-index
                  values that were observed 27 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

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  **
