PROJECT TITLE: Calculating the Joule Heating from the Ion Convection and Auroral Precipitation using DMSP Satellites

Mentors: Barbara Emery
Astrid Maute

Research Site: The High Altitude Observatory

ABSTRACT:
The goal of this project is to quantify the relative positions of the peak ion 
drifts and the peak auroral electron energy fluxes under various Interplanetary 
Magnetic Field (IMF B), solar wind, and seasonal conditions for input to the 
Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIEGCM).  The 
electric field (E) can be estimated from the ion drifts and the International 
Geomagnetic Reference Field (IGRF) magnetic field (B) for the earth.  The 
auroral Pedersen conductance can be estimated from the auroral electron energy 
flux and mean electron energies.  The Joule heating is estimated from the sum of 
the auroral and solar EUV Pedersen conductances multiplied by the electric 
field.  The Joule heat is the largest heat source in the high-latitude regions, and 
can exceed the global solar heating from EUV radiation during large geomagnetic 
storms in the upper atmosphere above 100 km (e.g. Knipp et al., 2004, Solar 
Physics, 224:495-5-5).  We will calculate the Joule heat along the satellite track 
and find the relative locations of the peak heating with respect to the peak ion 
drifts and electron energy fluxes on either side of the auroral oval.

We propose to look at several years of Defense Meteorological Satellite Program 
(DMSP) satellite data using the SSJ4 electron particle precipitation instrument 
and the Ion Drift Meter (IDM) instrument of the cross-track ion velocity.  We will 
start with DMSP-F13 (1995-2009) which was in an approximate dawn-dusk orbit.  We 
will only use DMSP satellite data when hourly or 5-min IMF and solar wind 
velocity (Vsw) data are available.  We will determine the location of the peak 
anti-sunward ion velocities in the polar cap and the location of the peak sunward 
ion velocities at lower latitudes in the dawn and dusk regions.  Similarly, we will 
locate the electron energy flux peaks from J4 in the dusk and dawn regions of the 
aurora, and we will also determine the fall-off of energy flux from the peaks 
towards the pole and the equator.  The poleward and equatorward boundaries of the 
aurora may be estimated from data threshholds, or from the list of boundaries 
provided by Dr. Thomas Sotirelis of the John Hopkins University Applied Physics 
Laboratory (JHU/APL).

Previous REU projects succeeded in reading and manipulating the input data sets, 
including finding peak data values and recognizing bad data.  The 2010 REU 
student (Liam Kilcommons) wrote a shell script to run an IDL code to read the 
binary SSJ4/SSJ5 DMSP files and convert them to ascii files.  The shell script can 
be called by a matlab Graphical User Interface (GUI), but also exists stand-
alone, and in a simpler matlab code created by the student called CRBPlot.m 
which finds the peak energy fluxes, mean energies, and plots the data.  The 2011 
REU student (Phoebe Tengdin) wrote matlab code to read ascii IDM files, remove IDM 
biases, and to find the peak ion drifts and the convection reversal boundary (CRB) 
where the ion drifts go to zero between the anti-sunward drifts in the polar cap 
and the sunward drifts near the auroral oval.  We anticipate that most of the 
Joule heating will be in the equatorward sunward drift regions where we anticipate 
the most overlap with the auroral oval, but the 2012 REU project will find this 
out.  

The codes to calculate the Pedersen auroral and EUV conductances, and to 
calculate the electric field using the IGRF model are currently in fortran.  The 
present project hopes to put a matlab wrapper around IGRF and to calculate the 
Joule heating along the DMSP satellite track in matlab and plot it and analyze it 
with respect to the relative locations of the peak ion drifts and the peak electron 
energy fluxes under various geophysical conditions.