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The
NOAA series of polar-orbiting satellites carry onboard a Space
Environment Monitor subsystem that measures Energetic Particles
along the orbit path.
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NOAA / POES Space Environment Monitor |
A New Product for Visualizing Energetic Particle Data from NOAA`s POES Satellites.
Follow the link to Flux Distribution maps in the direct access grid below.
Read about this product.
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POES Constellation, NOAA-15, NOAA-16, NOAA-17, NOAA-18, METOP-A, NOAA-19
Click image to view animation (8MB mpg)
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NOAA's Polar Orbiting Environmental Satellites (POES) carry a suite of instruments that measure the flux
of energetic ions and electrons at the altitude of the satellite. This environment varies as a result of solar and geomagnetic activity. Beginning with
the NOAA-15 satellite, an upgraded version of the Space Environment
Monitor (SEM-2) has been flown.
Because the SEM-2 instruments differ significantly from the earlier
SEM-1, there has been a complete revision to the data processing
and archiving process. A number of improvements have also been included.
Among these are incorporating up-to-date satellite orbit information
and magnetic field models in the calculation of various magnetic
coordinates, and improved data quality control.
The Total Energy Detector (TED) is designed to measure the
energy flux carried by auroral particles, both positively charged
ions (assumed here to be protons) and electrons, into the polar
atmosphere. The magnitude and spatial extent of this energy flux
are good measures of both the level of auroral activity and the
atmospheric response to that energy input.
The Medium Energy Proton and Electron Detector (MEPED) includes
a set of solid-state energetic particle detectors that monitor the
intensities of protons and electrons over a range extending from
30 keV to more than 200 MeV. Particles having those energies include
the radiation belt populations, solar particle events, and the lower
energy galactic cosmic rays. Enhanced fluxes
of these particles entering the atmosphere can produce significant
and widespread degradation in short-wave radio propagation; in extreme
cases even radio blackouts. The energetic particles also contribute
to astronaut radiation exposure, especially on high inclination
orbit missions during energetic solar particle events. |
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- Direct
Access to POES SEM data : These links will take you to all POES SEM
data and products which are updated daily.
| ./data |
./avg |
./cdf |
./YYYY (i.e., ./2008) |
./SATID (i.e., ./metop02) |
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16s averages, CDF format, SEM-2 only. |
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./txt |
./YYYY |
./SATID |
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16s averages, ASCII table, SEM-2 only. |
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./full |
./YYMM |
./SATID |
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full resolution, 2s values, native binary format. |
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./netcdf |
./YYYY |
./SATID |
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full resolution, 2s values, NetCDF format, under development. |
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./raw |
./YYMM |
./SATID |
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full resolution, 2s values, native binary format, Level-0, internal use. |
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./plots |
./qc |
./YYYY |
./SATID |
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Daily time series used for quality control, NO SCIENTIFIC VALUE, pdf. |
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./lshell |
./YYYY |
./SATID |
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L-shell plots by orbit, png images in tar file, under development. |
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./maps/png |
./YYYY |
./MM |
./PROJECTION |
Flux distribution maps, NEW. Read about these maps. |
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./recent |
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Most recent pngs, names never change, NEW. |
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./maps/mpg |
./YYYY |
./PROJECTION |
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Flux distribution maps as movies, NEW. |
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./recent |
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Most recent mpegs, names never change, NEW. |
| ./docs |
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Documentation and software, see details below. |
- In addition to the http access shown above, this same directory structure can be accessed though ftp (ftp://satdat.ngdc.noaa.gov/sem/poes/).
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- Documentation
files for Polar Orbiting Environmental Satellite (POES) SEM data,
prepared by the Space Weather Prediction Center:
- SEM-1 Documentation for TIROS-N through NOAA-14, (version
1.0 January 1985, 2.0 MB pdf ).
- SEM-2 Documentation for NOAA-15 and later satellites:SEM2v2.0.doc, rev 2006
Appendix A : Archive record description.
Appendix B : Conversion table for MEPED and TED counts.
Appendix C : TED Sensor Data Grouped by Unit Serial Number, rev 2006.
Appendix D : C Language Program to Read an Archive Record.
Appendix E : FORTRAN Language Program To Read an Archive Record, rev 2009.
Appendix F
: Procedures to recover energetic proton number fluxes from the Omnidirectional detector responses, rev 2006.
Appendix G: Processing Problems, Instrument Problems, Updated Information, rev 2007.
Errata for SEM2 Documentation
: rev 2006.
- NOAA-KLM
User's Guide with N' Supplement.
- January 7, 2002 -- Status
report for NOAA-12, NOAA-14, NOAA-15, & NOAA-16
- February 11, 2003 -- Status
report for NOAA-12, NOAA-14, NOAA-15, NOAA-16, &
NOAA-17
- January 8, 2004 -- Status
report for NOAA-12, NOAA-14, NOAA-15, NOAA-16, &
NOAA-17
- January 5, 2005 -- Status
report for NOAA-12, NOAA-14, NOAA-15, NOAA-16, &
NOAA-17
- July 17, 2006 -- NOAA-18
reprocessing.
- January 10, 2008 -- Status
report for NOAA-15, NOAA-16, NOAA-17, NOAA-18 & MetOp-02
- The NORAD ortital elements for NOAA and TIROS-
N satellites are available from CelestraK.
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2009-04-24 Fortran Error Corrected in Unpacking Routine
A minor error has been uncovered in the FORTRAN version of the SEM-2 archive file unpacking routine (subroutine readArcSub ) that is detailed in Appendix E of the SEM-2 Instrument Descriptions and Archive Data Documentation. About 20 lines from the end of this FORTRAN subroutine code the statement: if(mdf(2,3).eq.1) tedback(2,3) = -999. should be replaced with if(mdf(26,j).eq.1) tedback(2,3) = -999. A revised Appendix E (Appendix E_rev1.pdf) is available and the code file has been revised (readArcSub_v2.f).
This error affected only the background readout from the 30-degree, 1-20 keV proton analyzer in the TED instrument compliment. This single data point is the tedback(2,3) entry in the tedback array returned from the unpacking routine. The error arises only in cases when that data point was lost in the processing of the data received from the satellite and a default pad value was inserted in its place. In those instances the unpacking routine did not access the missing data flag correctly and returned a value of 1998848.0 for that tedback entry rather than the correct value of –999.0 for missing data. This particular error occurred on the average of 1 or 2 times a day and did not affect any other data point in the SEM-2 archive data. Finally, this error was not present in the C version of the SEM-2 archive data unpacking routine.
2008-04-22 MepOp Orbital Maneuvers
It has come to our attention that during instances when the MetOp satellite exercises orbital maneuvers the entire SEM-2 instrument is turned off. Unfortunately the data processing software does not recognize when the SEM-2 data processing unit (DPU) has been turned off and so assumes that the data received from the TED and MEPED detectors, that had been turned off, are valid in spite of the fact those data are zero-fill during these periods. The TED and MEPED instrument ON-OFF flags in the daily archive files are not properly set to OFF at these times.
Those periods of time during which the SEM-2 instrument on MetOp were turned off are:
April 19, 2007 between 0819:58 and 1616:14 UTC
April 24, 2007 between 0000:00 and 1359:27 UTC
July 12, 2007 between 0922:22 and 1538:22 UTC
Sept. 18, 2007 between 1454:10 and 2400:00 UTC
Sept. 19, 2007 between 0000:00 and 1402:58 UTC
Jan. 31, 2008 between 0921:30 and 1538:33 UTC
April 8, 2008 between 0732:23 and 2400:00 UTC
April 9, 2008 between 0000:00 and 0437:58 UTC
The TED and MEPED ON-OFF flags in the MetOp archive files for these days have been corrected and the corrected files are available.
2008-01-07 Revised NOAA-16 file for day 2007-07-09
It was discovered that orbital data contained in the NOAA-16 archive file for July 9, 2007 (day 190) was incorrect for times after 2035:11 UT. A revised NOAA-16 archive file for that day has been produced that eliminated records with incorrect orbital information.
2007-03-23 Revised NOAA-18 archive files
Revisions to NOAA-18 archive data files for July 23-24, 2005 and for the entire period July 11, 2006 through December 26, 2006 were necessary because incorrect calibration data for the TED instrument were used. These revisions impacted only the TED auroral particle energy flux values and many of the data quality flags. All of the MEPED data in the original archive data files were correct.
Users of TED data for these periods are advised to download the revised archive data files for NOAA-18.
2005-08-16 ERRATA: Software errors in unpackSem2.c since year
2000.
It has been brought to our attention by a user of POES SEM-2 data
that the C language archive unpacking routine returns anomalous
sensor values during periods where there are data missing as flagged
by 999. We have examined that code and uncovered two significant
errors in the C version of the code that have existed since 2000.
Both errors involve the way the C unpacker implements missing data
flags. The first error centered around the fact that missing data
flags associated with sensor data from the second half of the 32-second
archive record were being improperly unpacked from the binary archive
record. The consequences of that error were that TED and MEPED sensor
values during periods when data were missing were often improperly
flagged with valid data being set to -999. indicating missing data,
while entries that should have been flagged as missing data were
given count values of 19988488, the highest count value possible.
The second error also involved the implementation of missing data
flags and impacted P8 and P9 omni-directional detector data throughout
an entire 32-second archive record. The P8 and P9 data share the
same data word in the TIROS data format and readouts alternate between
the two. In the archive record the data listing for P8 alternates
between valid data readouts and values set to 0 in the archive format
while the P9 data alternates in the same fashion but with valid
readouts when the P8 value is zero. The existing documentation explains
this and a user is expected to extract only the appropriate entries
when using P8 and P9 data. During instances when data were missing,
the C unpacker assigned the missing data flag (-999.), in both the
P8 and P9 data, to the entry appropriate to 'no data' while the
entries appropriate to valid data were given count values of 19988488.
This count value is unphysical for P8 and P9 data.
Both these errors would have impact upon any analysis that had
not recognized these unphysical sensor count.
The FORTRAN version of the archive record unpacker did not have
either of these problems.
David S Evans <David.S.Evans@noaa.gov>
Corrected sofware (unpackSem2_v2.c) is now available
for distribution. |
- The Space Weather Prediction Center has a variety of displays available
of these data:
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- Static displays of NOAA data created for various projects:
- NOAA-11 anomalies plotted on a background of NOAA-10 electron
fluxes. (GIF)
- Stack plots showing the NOAA-12 > .3 MeV electrons at
L4.5 - L4.8 and GOES-8 > 2 MeV electrons at L6.6. These
plots show the affect of smoothing on the NOAA-12 data, an
algorithm for detecting NOAA-12 event start and peak times,
and an exponential decay model for those events. (PDF, 12/23/98)
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