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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!! 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 **
-