SIP/SOLAR2000 Professional Grade V2.37 hybrid solar irradiance model


The SIP/SOLAR2000 Professional Grade V2.36 solar irradiance model
is a binary IDL save file that runs with a Graphics User Interface
(GUI). Any platform that has licensed Research Systems, Inc (RSI)
Interactive Data Language (IDL) version 6.3 or higher can use this
model. However, if it is run from the downloaded self-extracting package,
Users of the SIP/SOLAR2000 PG model must also have Java v1.4 or higher running on
their system and an internet connection in order to obtain forecast data.


Starting with SIP/SOLAR2000 v2.23 and IDL 6.0 or higher, it is possible to run the
model on any platform without an IDL license. The IDL VM is available via free
download from the ITT web site.

You will need to login or register as a new user at:

Once you are logged in, visit the IDL Virtual Machine webpage for general information:

To download the IDL Virtual Machine, visit the ITT Visual Information Solutions at:

You will need to download the entire IDL 7.x Product (not the License Server) appropriate to
your operating system. It is downloaded as a compressed *.tar.gz file,
so depending on your operating system, you will need to uncompress it.
For example, double-click it, use a zip/unzip application, or for Linux/Unix systems,
see the man page for gzip, unzip, or tar (e.g., unnzip -x *.tar.gz, tar -xf *.tar). Be sure to
decompress the IDL 7.x product into a working directory you will find easy to work with
in subsequent uses (e.g., /apps/itt).

For a Linux/Unix installation, first set up couple of environmental variables.

1. For example with a Korn or Borne shell login, edit the .bashrc, .cshrc, or equivalent:

export IDL_DIR=/topdir/idl71 … whatever directory path to the idl installation, just above it’s bin directory
for a C-shell: setenv IDL_DIR /apps/itt/idl71

2. then, create an alias to idl, e.g. in the Borne or Korn shells:
alias idl=”/topdir/idl71/bin/idl”
for a C-shell, use: alias idl /topdir/idl71/bin/idl

3. You may need to set your environment to include your SIP working directory, e.g.
export PATH=$PATH:/home/user/SIP/SIPPGv237

4. Logout and log back in. Confirm it works by typing: idl …IDL should start up in demo mode.
Type exit to get out of the IDL demo mode.

5. Change your working directory to where you have SIP installed, then type:
idl -vm=sip_vm.sav

Mac users: a X-terminal window must first be opened.

(Please note that there is a space between “idl” and “-“.)
If you type simply: idl -vm
An IDL window will present you with a menu to navigate to the siv_vm.sat file

You should be ready to run SIP through its GUI at this point.

Windows NT and XT users: drag and drop the S2K sip_vm.sav application onto the
IDL VM icon to activate the program.


1. At, click on “Products -> SIP”, or go directly to:, and select the
“Download and Install SIP” link.

2. Register for updates with your name, email address, institution and company..

3. Click “Submit”.

4. Your Browser will display the link to an anonymous ftp directory, which will
contain files and/or subdirectories. Navigate to the version of SIP
you desire (e.g., SIP_Professional_Grade).

5. Click on the file to begin the download, saving it to a
directory of your choosing.

Note: If your Browser fails to work as described above, simply use an
FTP application or command, e.g., ftp
and use a binary “get” command. The username is spcusr, and the password
is usrspc

6. Decompress the zip file. Some Windows and Mac computers are already set up to decompress the file
if you simply double-click or right-click on the file.
You may want to place the new SIP folder in the desired subdirectory or
folder on your computer.

Alternatively you might use the “StuffIt Expander” decompression application
which is widely available. For Linux/Unix users, see the man page
for gzip, unzip (e.g., unzip -x

7. Read the s2k_readme text file, which contains the license agreement and
IDL SIP instructions for running the model.

Additional Notes:

For Windows VISTA:
a. See comment in SIP v2.37 notes.

For Windows 98/NT/XT/XP:
a. Move to any folder/directory as a default (e.g., SOLAR2000PG_v2_37)
which will contain all the files that will be necessary to run
SIP. You may need to create this folder: it will serve as the
default IDL working directory to run SIP.
b. Open a Zip application, e.g., Aladdin StuffIt Expander. If you don’t
have a Zip file application, they are widely available on the Internet.
c. Unzip the downloaded zip file. Depending on the application, this
may be a two-step process. Note: Because of the wide variety of
decompression applications, you will need to follow the instructions
provided with the application.
d. All the necessary files should be should be created under an additional
SIP subdirectory. You may want to rename or move this subdirectory with
all it’s files to another location of your choosing. Be certain you have
full read/write/execute privileges to all the files.
e. Read the s2k_readme text file, which contains the license agreement and
IDL SIP instructions for running the model.

If you are having difficulty installing SIP, you may need 4 applications:

(1) A terminal window application
(2) A file decompression application
(3) An FTP application
(4) An X-windows application

Fortunately, nearly all these applications can be found, for free, at:

(1) A Terminal window is most probably already on your system and you will
likely find it in your Applications/Programs folder with a “Terminal” or
“Console” name. It is the bare-bones text-only application that just opens
a window for typing in commands. It is from this window you can perform basic
commands to ftp to a server, unpack compressed files, start SIP/SOLAR2000, etc.,
but without experience in doing so you will not find it very helpful. Some of
the mysteries of using text-based commands can be found in a number of “how-to”
books at your local computer store.

(4) An X-window application may necessary to display the plots and graphics
the IDL VM needs. It has been around the science community for some time,
with it’s origins in Unix, providing a common set of tools. It can also be
found at, but you will find it a bit complex in
getting started. There is a fairly expensive application that has an
integrated Window interface (Do a web search on “Hummingbird X-windows”).
However, it does come with a terminal window, ftp, etc. applications that
should allow you to start SIP.

You will find getting all this started may have a fairly steep learning curve, but
these are fairly common applications necessary for most space-science
applications (IDL is the most commonly used programming language in the
space-weather community), and having these tools will prove to be useful
later on.


1. Start an IDL session (IDL v6.3 or higher). THE DEFAULT DIRECTORY
2. Double-click the “launch_sip” icon (If you already have IDL installed, you can
start a terminal session, and type “sip” at the command line in IDL).
The model will start and you will see the SIP GUI appear in a separate window.
Some platforms are case-sensitive in IDL (e.g. UNIX systems) so please note
the lower-case characters.
3. To run the SIP application (it can only be run through
the GUI), select the desired input parameters from the left-side
list menus (5 menus):
a. Start year [1947-2001]
b. Start day of year [1-366] (Note: only leap years have 366 days;
if day 366 is used for a non-leap year, the program defaults to
1980-366 as the start day and “invalid starting date” is printed in
the IDL output log.)
c. Number of days to model [1-1000] (Note: some computers may have
limited memory and will not run 1000 days at a time; if this
is the case, either increase the computer memory allocated to
IDL or run a smaller number of days.)
d. Spectral format [indices only, 1 nm bin size full solar spectrum,
39 EUV lines and wavelength groups in the EUV91/EUV97 format,
809 EUV 1 Angstrom lines in the SC#21REFW format. NOTE: the energy
flux totals in the 1 nm bin and 809 wavelength bins will not equal
each other since the 1 nm flux value is created proportional to the
photon flux value divided by the center of the wavelength bin while
the 809 flux value is created proportional to the photon flux value
divided by the 1 Angstrom wavelength value from SC21REFW. This
algorithm may be changed in a future upgrade.]
e. Flux units [SI (W m-2), photon flux (photons cm-2 s-1), energy
flux (ergs cm-2 s-1)] (Note: all wavelength units are in nm and
the +-1 sigma uncertainties for each wavelength are listed. Currently,
the value of 1.00 is used as a placeholder for this field in the
1 nm and 39 wavelength group formats. The delta-lambda unit for
the fluxes is determined by the bandpass in each wavelength format.)
4. Click the “Run” button. THE RUN BUTTON MUST BE CLICKED FOR
After a short time, you will see several panels of plots in the
GUI window. At this point, the application has run the modeled
irradiances for the input parameters that were selected. In the same
folder as the application, you will find 3 new files:

s2k_output.txt – a text file of irradiance or indices data. This file
is accessed from the GUI through the “S2K Output”
button; the text can be selected, copied, and
pasted into another application or the file can be
opened separately as a text file.
s2k_tsi.txt – a text file of the solar irradiance spectrum (1 nm bins)
for the first day of the run. This file is accessed
from the GUI through the “S2K spectrum” button.
s2k_plot.jpg – a JPEG picture file of the same data displayed in the
GUI window for this run of the model. The 3 rows of
plots include:
TOP ROW: Integrated solar spectrum (left), coronal input
in F10.7 units (center), and chromospheric input in
Lyman-alpha (or Mg II cwr reported in Lyman-alpha
units) (right);
MIDDLE ROW: first day solar spectrum in SI units in 1
nm bin (left) and first day soft X-ray/EUV spectrum
through Lyman-alpha in SI units in 1 nm bins (right);
BOTTOM ROW: comparison of the F10.7 (dash line) and
E10.7 (dotted line) proxies for the time period
Selected (day 0 is the starting date).

5. You may print your S2K Output file to a local printer or a PS file if that
is an option of your printer with the “Print” button.
6. You may click the “About S2K” button to read the LICENSE AGREEMENT,
the SOLAR2000 USER GUIDE (this document).
7. You may click the SET Sun-Planet logo to view the “About SpaceWx”
text file containing general information about SpaceWx.
8. To quit the SIP application. click the “Quit” button.


1. If the SOLAR2000 Research Grade V2.37 The GUI is being asked to display
GUI application is run with a number invalid dates and/or indices and
of days to model that extends past the the program must be restarted. In
last valid date (see item 7.b above), this case, simply exit IDL, start
the program will ungraciously stop. a new IDL session, and restart the
Why? GUI, taking care to not run the
model past the last valid date.

2. If the “Print” button on the GUI is The file “s2k_plot.tif” is the
used for printing the plot file the default plot file and is fully
right-hand border of the displayed displayed with graphic software.
plot may not be reproduced. Is there Other print options include using
another solution for this? the cursor to click and highlight
one of the three plot panels then
print that panel from IDL. Another
alternative is to highlight a
panel, copy the plot panel contents
into the computer’s internal buffer
or ‘clipboard’, then paste, print,
and/or save the graphic within a
graphics program.

3. IDL, in this GUI application, does Set the monitor to 8-bit or, as an
not properly display colors if the alternative, 24-bit color.
monitor is set to 16-bit color. Why?

4. I would like to have the capability This capability is being developed.
of using a callable IDL subroutine It will be possible to use this as
module rather than a GUI. This a special subroutine in the future.
would serve better in an IDL or
Fortran routine that needs solar
irradiances updated in by a time
step. Can you provide this?

5. I would like to have the model This capability is planned for a
extended to shorter wavelengths and future upgrade of SOLAR2000.
higher energies in the X-rays
(0.05 – 1.8 nm). When will this be

6. There is a discontinuity for E81 This artifact was minimized in v1.16
values between the beginning of one by using an 81-day convolution. How-
time frame run and the end of a ever, a user is advised to create a
previous run. How do I remove this? data set of desired length and to
use his or her own smooth algorithm.

7. Some of the highest resolution The SC21REFW format is used for the
wavelengths in the 809 template are 809 wavelength bin format and this
not uniform in grid-spacing and are format does not have uniform spacing
repeated. Is this correct? between the lines. In addition, some
values may appear to be repeated,
e.g., 6.63 nm, but is a result of
truncation of finer resolution lines
(6.630 Fe XII and 6.637 Fe XVI). The
v1.21 upgrade changed the lines to
be reported with 3 decimal places to
avoid this truncation confusion.

8. How do I find the uncertainty in The 1 sigma error of reported
the irradiances and how is it instrument measurement error plus
calculated? linear regression uncertainty can
be found as a fraction (1.0 = 100%)
in the 809 wavelength (highest
resolution) listing. In the other
listings, there are placeholders
right now. However, since they are
all coarser resolution than the 809
listing, a simple wavelength bin-
average would be acceptable. A
future version will incorporate the
1 sigma error for all formats.

9. Is it possible to get irradiances Yes, there are system, operational,
closer to the current epoch, nowcast, and professional grade SOLAR2000
or forecast irradiances in addition versions that produce all these
to the Research grade version? irradiances. For more information,
including high time resolution data,
please contact SpaceWx or visit the
products and services link at Additionally,
NOAA/SEC hosts the daily nowcast
SOLAR2000 irradiances on their
server at

10. Can I retrieve SOLAR2000 products E10.7 and Lyman-alpha are available
without using IDL? for 5 solar cycles at the products
links at These
are daily historical data for
Research use. Current epoch, daily
irradiance products are also
provided at that web site location.
In the second half of 2003, SET
plans to release historical 3-hourly
data sets as well as forecast
data sets, both of which will be
provided for a fee.

11. Why doesn’t the S(t) value of the The solar integrated spectrum (often
SOLAR2000 output match the variability referred to as S(t) in SOLAR2000
in the total solar irradiance (TSI)? literature) is only variable between
1-122 nm in versions 1.yz. It is the
integrated spectrum and will in-
creasingly become the same as the
variable TSI in versions 2.yz, 3.yz,
and 4.yz. In version 2.yz, the
spectrum is variable between 1-420
nm but does not include irradiance
deficit due to sunspots.

12. Why are there double entries for The ASTM-E490 placeholder spectrum
some of the wavelengths longwards of was used in earlier versions and had
Lyman-alpha? a problem of double entries. That
placeholder spectrum was upgraded to
the officially released version of
the reference spectrum starting with
SOLAR2000 version 1.24.

13. Why is the value of E10.7 in older As the accuracy and precision of the
model versions different from the EUV wavelengths are improved in
v2.21 release? Model releases, the value of E10.7
will change since it is the inte-
grated 1-105 nm EUV energy flux and
the latter changes. As measurements
improve through time, the value of
E10.7, though changing, will more
and more approach a fixed level for
given solar conditions. For example,
the 1-sigma E10 v1.15:v1.24 ratio is
6.15% while v1.20:v1.24 is 0.38%.
See the discussion in version 2.21
release related to “Known differen-
ces…” items 3 and 4. We have
identified a process to create a
“standard” by which to judge E10.7
and all other integrated irradiance
proxies and work is progressing
to create this standard. Our AFRL
colleagues will create a several
solar cycle derived F10.7 from an
ensemble of satellite drag data and
this independent measure of what
the general level of solar flux
should have been will be used to
evaluate future E10.7.

14. Is there a Fortran version of A Fortran version of the model is
SOLAR2000 available? not under development since most of
our efforts are going into improve-
ment in various spectral ranges.
However, current and selected hist-
orical data files are available at
the web site.
Also, the web
site points to links with older EUV
models that are written in Fortran.

15. Are the plotted values correct in No, the units are high by a factor
the v2.21 GUI window, row 2, panel of 1E3. A typo in the v2.21 plot
(e) (EUV spectrum)? module uses the energy flux rather
than SI units as in row 2, panel
(d). This has been corrected in
v1.24a, v1.25, and versions after

16. Which exospheric temperatures are In all versions except for v2.21
being shown in the Tinf column of these are the daytime average
the S2K_output.txt file? exospheric temperature. They are not
the subsolar point temperature as
has been reported earlier since a
cos(72) (72 deg is the angle between
local atmosphere normal vector and
the Sun-line vector) is used in the
physics-based 1DTD model. This angle
was selected because the 1DTD temp-
eratures and neutral densities for
1976-200 (SC21REFW) and 1979-050
were very close to the MSIS-86
output for those dates. In addition,
this angle provides an average
daytime exospheric temperature for 6
years (Jan 1 1996 – Dec 31 2001)
that is 1.3 times the J70 nighttime
minimum exospheric temperature for
the same period. The 1-sigma
variation about this average temp-
erature is +/-6.4%. Altogether,
these point to a self-consistent
exospheric temperature for input
spectral solar flux. 1DTD does not
use the E10.7 integrated irradiance
proxy but uses the 39 wavelength
groups and lines that are common in
aeronomy. In v2.21, a conversion was
applied to the temperatures to
produce an absolute value very close
to J70 nighttime minimum exospheric
temperatures. We have decided not to
use this conversion in all other
releases of this Tinf parameter.

17. Is there a SC21REFW type of template We plan to extend the current
for wavelengths between 121.5 and SC21REFW type of wavelength temp-
199.5 nm? late into this spectral region in
an upcoming release of the model.

18. Why are there slight differences in The S2K PG proxy file is generated
the output numbers between the RG on an operational server and will
and PG model versions? have slightly different values for
either the F10 or Ly-a and/or their
81-day smoothed values. This will
translate to small output
differences in the integrated
irradiance proxies since the data
on the server is continually being
updated and may also be running
with a different version of S2K.


All messages and errors that occur while running the SIP application
will appear in the IDL Output log which is often a separate window on many
platforms. While we have done our utmost to provide a robust, validated, and
rigorously tested product, WE ARE VERY INTERESTED TO LEARN ABOUT ANY
contact us at if you feel that there
is a problem with this application. We realize that users are often under
time constraints and are working to deadlines. Therefore, we will do our
utmost to fix any significant problems that you bring to our attention and
we will notify you of the fix in a timely way. General concerns that are of
interest to a broad community of users will be posted in the FAQ section of
this document.

S2KPG V2.37 1 Sep 2011