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== DMSP SSJ4 Midnight Boundary Index Obtained from Precipitating Electrons ==

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=== DATA FILES ===

Please read the [[DMSP:Rules of the Road|"Rules of the Road" notice]] before using any of these data.

The Midnight Boundary Index is an estimate of the equatorward boundary of precipitating auroral electrons as determined by the SSJ/4 (F06 through F15) and SSJ/5 (F16 and beyond) instruments on DMSP spacecraft. Midnight Boundary data are available in the [[Instruments:ehp|CEDAR Database]] and also in yearly ascii files below.

In March 2009, all the files were replace to add additional information.  Previously, only the year, daynumber, UTsec, and estimated midnight equatorward boundary in magnetic latitude were given.  The additional information is the satellite ID (F06=7540, F07=8541, F08=9543, F09=0542, F10=1544, F11=2546, F12=3545, F13=4547, F14=5548, F15=6549, F16=7454, F17=8550), where the ten's place digit indicates '4' or '5' for SSJ/4 or SSJ/5.  Extra parameters are the geographic latitude times 10 and the magnetic local time (MLT) in seconds of the equatorward boundary crossing which is then estimated at the midnight MLT.

* [http://cedarweb.hao.ucar.edu/cgi-bin/cedar_file_access.pl?filename=mnit/mnit1983.txt 1983]
* [http://cedarweb.hao.ucar.edu/cgi-bin/cedar_file_access.pl?filename=mnit/mnit1984.txt 1984]
* [http://cedarweb.hao.ucar.edu/cgi-bin/cedar_file_access.pl?filename=mnit/mnit1985.txt 1985]
* [http://cedarweb.hao.ucar.edu/cgi-bin/cedar_file_access.pl?filename=mnit/mnit1986.txt 1986]
* [http://cedarweb.hao.ucar.edu/cgi-bin/cedar_file_access.pl?filename=mnit/mnit1987.txt 1987]
* [http://cedarweb.hao.ucar.edu/cgi-bin/cedar_file_access.pl?filename=mnit/mnit1988.txt 1988]
* [http://cedarweb.hao.ucar.edu/cgi-bin/cedar_file_access.pl?filename=mnit/mnit1989.txt 1989]
* [http://cedarweb.hao.ucar.edu/cgi-bin/cedar_file_access.pl?filename=mnit/mnit1990.txt 1990]
* [http://cedarweb.hao.ucar.edu/cgi-bin/cedar_file_access.pl?filename=mnit/mnit1991.txt 1991]
* [http://cedarweb.hao.ucar.edu/cgi-bin/cedar_file_access.pl?filename=mnit/mnit1992.txt 1992]
* [http://cedarweb.hao.ucar.edu/cgi-bin/cedar_file_access.pl?filename=mnit/mnit1993.txt 1993]
* [http://cedarweb.hao.ucar.edu/cgi-bin/cedar_file_access.pl?filename=mnit/mnit1994.txt 1994]
* [http://cedarweb.hao.ucar.edu/cgi-bin/cedar_file_access.pl?filename=mnit/mnit1995.txt 1995]
* [http://cedarweb.hao.ucar.edu/cgi-bin/cedar_file_access.pl?filename=mnit/mnit1996.txt 1996]
* [http://cedarweb.hao.ucar.edu/cgi-bin/cedar_file_access.pl?filename=mnit/mnit1997.txt 1997]
* [http://cedarweb.hao.ucar.edu/cgi-bin/cedar_file_access.pl?filename=mnit/mnit1998.txt 1998]
* [http://cedarweb.hao.ucar.edu/cgi-bin/cedar_file_access.pl?filename=mnit/mnit1999.txt 1999]
* [http://cedarweb.hao.ucar.edu/cgi-bin/cedar_file_access.pl?filename=mnit/mnit2000.txt 2000]
* [http://cedarweb.hao.ucar.edu/cgi-bin/cedar_file_access.pl?filename=mnit/mnit2001.txt 2001]
* [http://cedarweb.hao.ucar.edu/cgi-bin/cedar_file_access.pl?filename=mnit/mnit2002.txt 2002]
* [http://cedarweb.hao.ucar.edu/cgi-bin/cedar_file_access.pl?filename=mnit/mnit2003.txt 2003]
* [http://cedarweb.hao.ucar.edu/cgi-bin/cedar_file_access.pl?filename=mnit/mnit2004.txt 2004]
* [http://cedarweb.hao.ucar.edu/cgi-bin/cedar_file_access.pl?filename=mnit/mnit2005.txt 2005]
* [http://cedarweb.hao.ucar.edu/cgi-bin/cedar_file_access.pl?filename=mnit/mnit2006.txt 2006]
* [http://cedarweb.hao.ucar.edu/cgi-bin/cedar_file_access.pl?filename=mnit/mnit2007.txt 2007]
* [http://cedarweb.hao.ucar.edu/cgi-bin/cedar_file_access.pl?filename=mnit/mnit2008.txt 2008]
* [http://cedarweb.hao.ucar.edu/cgi-bin/cedar_file_access.pl?filename=mnit/mnit2009.txt 2009]

Midnight Boundary data are also available from AFRL [mailto:gordon.wilson@hanscom.af.mil upon request]. If the data are used in scientific studies, they should be referred to as "The Air Force Research Laboratory Auroral Boundary Index" and acknowledged as being provided by the USAF Research Laboratory, Hanscom AFB, MA. These data are in the public domain and no further permission is required. Please send a courtesy copy of any publications using the Boundary Index to Dr. K. Kadinsky-Cade

=== PLOTS ===

This x-y plot shows Midnight Boundary variations during a 27 day period.

[[Image:DMSP_dmspssj4_mid_small.gif|Thumbnail Plot of Midnight Boundary Index]]

To see plots of recent values of the midnight boundary index, click on the items below. Files of the values plotted here and older values along with a "readme" file describing the files are available [mailto:frederick.rich@hanscom.af.mil upon request].

* [http://cedarweb.hao.ucar.edu/dmsp/dmspssj4_mid_01jan9420mar94.gif 01 Jan 1994 to 20 Mar 1994]
* [http://cedarweb.hao.ucar.edu/dmsp/dmspssj4_mid_21mar9409jun94.gif 21 Mar 1994 to 09 Jun 1994]
* [http://cedarweb.hao.ucar.edu/dmsp/dmspssj4_mid_10jun9429aug94.gif 10 Jun 1994 to 29 Aug 1994]
* [http://cedarweb.hao.ucar.edu/dmsp/dmspssj4_mid_30aug9418nov94.gif 20 Aug 1994 to 18 Nov 1994]
* [http://cedarweb.hao.ucar.edu/dmsp/dmspssj4_mid_19nov9407feb95.gif 19 Nov 1994 to 07 Feb 1995]
* [http://cedarweb.hao.ucar.edu/dmsp/dmspssj4_mid_08feb9529apr95.gif 08 Feb 1995 to 29 Apr 1995]
* [http://cedarweb.hao.ucar.edu/dmsp/dmspssj4_mid_30apr9519jul95.gif 30 Apr 1995 to 19 Jul 1995]
* [http://cedarweb.hao.ucar.edu/dmsp/dmspssj4_mid_20jul9508oct95.gif 20 Jul 1995 to 08 Oct 1995]
* [http://cedarweb.hao.ucar.edu/dmsp/dmspssj4_mid_09oct9528dec95.gif 09 Oct 1995 to 28 Dec 1995]
* [http://cedarweb.hao.ucar.edu/dmsp/dmspssj4_mid_29dec9518mar96.gif 29 Dec 1995 to 18 Mar 1996]
* [http://cedarweb.hao.ucar.edu/dmsp/dmspssj4_mid_19mar9607jun96.gif 19 Mar 1996 to 07 Jun 1996]
* [http://cedarweb.hao.ucar.edu/dmsp/dmspssj4_mid_08jun9627aug96.gif 08 Jun 1996 to 27 Aug 1996]
* [http://cedarweb.hao.ucar.edu/dmsp/dmspssj4_mid_28aug9616nov96.gif 28 Aug 1996 to 16 Nov 1996]
* [http://cedarweb.hao.ucar.edu/dmsp/dmspssj4_mid_17nov9605feb97.gif 17 Nov 1996 to 05 Feb 1997]
* [http://cedarweb.hao.ucar.edu/dmsp/dmspssj4_mid_06feb9727apr97.gif 06 Feb 1997 to 27 Apr 1997]
* [http://cedarweb.hao.ucar.edu/dmsp/dmspssj4_mid_28apr9717jul97.gif 28 Apr 1997 to 17 Jul 1997]
* [http://cedarweb.hao.ucar.edu/dmsp/dmspssj4_mid_18jul9706oct97.gif 18 Jul 1997 to 06 Oct 1997]
* [http://cedarweb.hao.ucar.edu/dmsp/dmspssj4_mid_07oct9726dec97.gif 07 Oct 1997 to 26 Dec 1997]
* [http://cedarweb.hao.ucar.edu/dmsp/dmspssj4_mid_27dec9717mar98.gif 27 Dec 1997 to 17 Mar 1998]
* [http://cedarweb.hao.ucar.edu/dmsp/dmspssj4_mid_18mar9806jun98.gif 18 Mar 1998 to 06 Jun 1998]
* [http://cedarweb.hao.ucar.edu/dmsp/dmspssj4_mid_07jun9826aug98.gif 07 Jun 1998 to 26 Aug 1998]
* [http://cedarweb.hao.ucar.edu/dmsp/dmspssj4_mid_27aug9815nov98.gif 27 Aug 1998 to 15 Nov 1998]
* [http://cedarweb.hao.ucar.edu/dmsp/dmspssj4_mid_16nov9804feb99.gif 16 Nov 1998 to 04 Feb 1999]
* [http://cedarweb.hao.ucar.edu/dmsp/dmspssj4_mid_05feb9926apr99.gif 05 Feb 1999 to 26 Apr 1999]
* [http://cedarweb.hao.ucar.edu/dmsp/dmspssj4_mid_27apr9916jul99.gif 27 Apr 1999 to 16 Jul 1999]
* [http://cedarweb.hao.ucar.edu/dmsp/dmspssj4_mid_17jul9905oct99.gif 17 Jul 1999 to 05 Oct 1999]
* [http://cedarweb.hao.ucar.edu/dmsp/dmspssj4_mid_06oct9925dec99.gif 06 Oct 1999 to 25 Dec 1999]
* [http://cedarweb.hao.ucar.edu/dmsp/dmspssj4_mid_26dec9915mar00.gif 26 Dec 1999 to 15 Mar 2000]
* [http://cedarweb.hao.ucar.edu/dmsp/dmspssj4_mid_16mar0004jun00.gif 16 Mar 2000 to 04 Jun 2000]
* [http://cedarweb.hao.ucar.edu/dmsp/dmspssj4_mid_05jun0024aug00.gif 05 Jun 2000 to 24 Aug 2000]
* [http://cedarweb.hao.ucar.edu/dmsp/dmspssj4_mid_25aug0013nov00.gif 25 Aug 2000 to 13 Nov 2000]
* [http://cedarweb.hao.ucar.edu/dmsp/dmspssj4_mid_14nov0002feb01.gif 14 Nov 2000 to 02 Feb 2001]
* [http://cedarweb.hao.ucar.edu/dmsp/dmspssj4_mid_03feb0124apr01.gif 03 Feb 2001 to 24 Apr 2001]
* [http://cedarweb.hao.ucar.edu/dmsp/dmspssj4_mid_25apr0114jul01.gif 25 Apr 2001 to 14 Jul 2001]
* [http://cedarweb.hao.ucar.edu/dmsp/dmspssj4_mid_15jul0103oct01.gif 15 Jul 2001 to 03 Oct 2001]
* [http://cedarweb.hao.ucar.edu/dmsp/dmspssj4_mid_04oct0123dec01.gif 04 Oct 2001 to 23 Dec 2001]
* [http://cedarweb.hao.ucar.edu/dmsp/dmspssj4_mid_24dec0114mar02.gif 24 Dec 2001 to 14 Mar 2002]
* [http://cedarweb.hao.ucar.edu/dmsp/dmspssj4_mid_15mar02_03jun02.gif 15 Mar 2002 to 03 Jun 2002]
* [http://cedarweb.hao.ucar.edu/dmsp/dmspssj4_mid_04jun0223aug02.gif 04 Jun 2002 to 23 Aug 2002]
* [http://cedarweb.hao.ucar.edu/dmsp/dmspssj4_mid_24aug0212nov02.gif 24 Aug 2002 to 12 Nov 2002]
* [http://cedarweb.hao.ucar.edu/dmsp/dmspssj4_mid_13nov0201feb03.gif 13 Nov 2002 to 1 Feb 2003]
* [http://cedarweb.hao.ucar.edu/dmsp/dmspssj4_mid_02feb0323apr03.gif 2 Feb 2003 to 23 Apr 2003]
* [http://cedarweb.hao.ucar.edu/dmsp/dmspssj4_mid_24apr0313jul03.gif 24 Apr 2003 to 13 Jul 2003]
* [http://cedarweb.hao.ucar.edu/dmsp/dmspssj4_mid_14jul0302oct03.gif 14 Jul 2003 to 02 Oct 2003]
* [http://cedarweb.hao.ucar.edu/dmsp/dmspssj4_mid_03oct0322dec03.gif 03 Oct 2003 to 22 Dec 2003]
* [http://cedarweb.hao.ucar.edu/dmsp/dmspssj4_mid_23dec0312mar04.gif 23 Dec 2003 to 12 Mar 2004]
* [http://cedarweb.hao.ucar.edu/dmsp/dmspssj4_mid_13mar0401jun04.gif 13 Mar 2004 to 01 Jun 2004]
* [http://cedarweb.hao.ucar.edu/dmsp/dmspssj4_mid_02jun0421aug04.gif 02 Jun 2004 to 21 Aug 2004]
* [http://cedarweb.hao.ucar.edu/dmsp/dmspssj4_mid_22aug0410nov04.gif 22 Aug 2004 to 10 Nov 2004]
* [http://cedarweb.hao.ucar.edu/dmsp/dmspssj4_mid_11nov0431jan05.gif 11 Nov 2004 to 31 Jan 2005]
* [http://cedarweb.hao.ucar.edu/dmsp/dmspssj4_mid_01feb0522apr05.gif 01 Feb 2005 to 22 Apr 2005]
* [http://cedarweb.hao.ucar.edu/dmsp/dmspssj4_mid_23apr0512jul05.gif 23 Apr 2005 to 12 Jul 2005]
* [http://cedarweb.hao.ucar.edu/dmsp/dmspssj4_mid_13jul0501oct05.gif 13 Jul 2005 to 01 Oct 2005]
* [http://cedarweb.hao.ucar.edu/dmsp/dmspssj4_mid_02oct0521dec05.gif 02 Oct 2005 to 21 Dec 2005]
* [http://cedarweb.hao.ucar.edu/dmsp/dmspssj4_mid_22dec0511mar06.gif 22 Dec 2005 to 11 Mar 2006]

Written by Frederick Rich.  Point of Contact: [mailto:gordon.wilson@hanscom.af.mil Dr. Gordon Wilson]

----

=== CONCEPT ===

It has long been known that increased auroral activity, as indicated by many ionospheric and magnetospheric parameters such as brightness of auroral arcs, disturbances in the magnetic field, magnitude of the convection electric field and magnitude of field aligned currents, is accompanied by the expansion of the auroral oval.

A statistical study of the electron precipitation observed by SSJ4 instruments on DMSP spacecraft to Kp values was done by Gussenhoven et al. (1981). They determined the regression coefficients for a linear fit of equatorward auroral boundaries for 13 of the 24 hourly local time sectors and compared the results to the Kp indices. They identified equatorward auroral boundaries by hand, using precipitating electron measurements made onboard the DMSP/F2 satellite. A follow-on study (Gussenhoven et al., 1983) developed a computer algorithm for boundary selection and increased the database to 20 of 24 local time sectors by including data from DMSP F4. This work has continued to date with all available data from the SSJ4 instruments flown on DMSP spacecraft.

Although the auroral equatorward boundary, when drawn in geomagnetic coordinates, is nearly circular for all levels of auroral activity, its center is offset from the magnetic pole toward the post-midnight local time sector. The offset is a function of magnetic activity. Therefore, individual boundary measurements made for the same auroral activity, but at different local times will differ, and, as such, cannot be directly scaled to auroral activity without removing the local time variation. Removal of the local time variation is reasonably easy to accomplish by statistically determining the position of the auroral oval for every local time sector as a function of some magnetic activity index, such as Kp.

=== REFERENCES ===

* Gussenhoven, M.S., D.A. Hardy, and W.J. Burke, DMSP/F2 electron observations of equatorward auroral boundaries and their relationship to magnetospheric electric fields, J. Geophys. Res., 86, 768, 1981.
* Gussenhoven, M.S., D.A. Hardy, N. Heinemann, and E. Holeman, 1978 Diffuse Auroral Boundaries and a Derived Auroral Boundary Index, AFGL-TR-82-0398, Air Force Geophysics Laboratory, Hanscom AFB, MA, (ADA130175), 1982.
* Gussenhoven, M.S., D.A. Hardy, and N. Heinemann, Systematics of the equatorward diffuse auroral boundary, J. Geophys. Res., 88, A7, 5692-5708, 1983.
* Hardy, D. A., and M. S. Gussenhoven, A Statistical Model of Auroral Electron Precipitation, J. Geophys. Res., 90, A5, 4229-4248, 1985.
* Schumaker, T.L., D.A. Hardy, S. Moran, A. Huber, J. McGarity, and J. Pantazis, Precipitating lon and Electron Detectors SSJ/4) for the Block 5D/Flight 8 DMSP Satellite, AFGL-TR-884030, Air Force Geophysics Laboratory, Hanscom AFB, MA, (ADA203990) 1988.
* Madden, D., and M. S. Gussenhoven, Auroral Boundary Index from 1983 to 1990, Tech Report GL-TR-90-0358, Air Force Geophysics Laboratory, Hanscom AFB, MA, 21 Dec. 1990.

=== Last Updated ===
Last Update of Page Format: 16 May 2006 by Frederick Rich. Point of Contact: [mailto:gordon.wilson@hanscom.af.mil Gordon Wilson]

Last Update: 06 Mar 2009 by [mailto:emery@ucar.edu Barbara Emery]

[[Category:DMSP|ssj4_midnit]]