https://spdf.gsfc.nasa.gov/pub/data/wind/swe/ascii/swe_kp_unspike/aareadme.txt

Readme file for SWE KP data 

This directory contains a twice-improved version of Wind/SWE
key parameter (KP) data originally computed in near real time at
the ISTP Central Data Handling Facility and subsequently at the
"Polar-Wind-Geotail Facility," both at GSFC.  The data consist
of ~92-s resolution plasma (proton) flow velocities (speed,
Cartesian components and/or angles), densities and thermal
speeds (or temperatures).  In particular, the version in this
directory contains flow speed, Cartesian components of the
flow velocity, density and temperature.

As described in the readme associated with the MIT-accessible
version of these data at ftp://space.mit.edu/pub/plasma/wind/kp_files/,
the parameters are derived by assuming convecting isotropic
Maxwellian distributions, and by combining the results of 3-point
fits to observations made along each of several look directions.

The originally computed version of the data are CDAWeb-
accessible at http://cdaweb.gsfc.nasa.gov/  A version of the data
from which many single-point data spikes have been removed at MIT
is ftp-accessible as daily ASCII files from MIT at
ftp://space.mit.edu/pub/plasma/wind/kp_files/.
MIT tested for the relative difference between the value of
flow speed (V), density (N) or thermal speed (W) and the median 
value of the seven points centered on the point being tested.
If this relative difference exceeded 0.1, 0.5, or 1.0
for V, N or W, respectively, the record was rejected.  For
example, if |N - Median(N)| / Median(N) > 0.5, the record was
rejected.

Both the CDAWeb and MIT-accessible versions of the data have
both flow angles and Cartesian components, and have thermal
speeds rather than temperatures.  Both of these versions also
contain, in addition to solar wind data, data from the non-solar
wind phases of the Wind orbit.

The data files in this directory were created in 2005-6, from the
MIT-resident files, as part of the effort to create ACE, Wind and
IMP 8 data files shifted to the Earth's bow shock nose, and a
merger thereof called the high-resolution OMNI data set.
It should be noted that we were encouraged by the instrument
team at MIT to use this product for our purposes rather than
the also-available non-linear anisotropic fit based or moments
analysis based SWE parameters, owing to the greater "robustness"
of the KP data.  Further discussion of this choice, as well as
comparisons among the various SWE plasma parameter data sets,
is available in the documentation of the high-resolution OMNI
data product at TBD.

The format for the records of this new product is given below.
Note that in the process, we have eliminated the flow angles (in
favor of the Cartesian components), have converted the thermal
speeds to equivalent temperatures (T = 60.5 * W**2, where T
is temperature in deg K and W is thermal speed in km/s), and have
created annual files rather than the daily files MIT holds.

More significantly, we undertook to further clean the data files.
First, we eliminated all non-interplanetary time intervals using (1) the
Wind bow shock timing information given by the Wind/MFI team at
http://wind.nasa.gov/mfi/bow_shock.html  through 2003, day 286,
and our own identifications of the very few bow shock crossings past
that date.  MIT offers its own identifications at
http://web.mit.edu/afs/athena/org/s/space/www/wind/wind_data_appendix.html

Secondly, we removed some single point spikes which had survived
the MIT spike removal program   For each parameter P (P = V, Vx,
Vy, Vz, N, T in sequence), we assessed the goodness of each point by
forming a 4-point average <P> of the two points most immediately preceding
and following the point being tested.  The average <P> has the rms
standard deviation "sigma."  Given the natural ~92 sec resolution of the
data, the first and last point in each test were typically separated by
about six minutes. But this could be longer in the presence of data gaps.
 To test a point, we required that the first and last point used in the test
lay within 60 minutes of each other.  Otherwise we have a new data
segment.  The first and last two points of each such data segment were
assumed to be good points.

Two conditions were required to declare a spike.  First, it was
required that |P-<P>| > 4 * sigma, for each P.  Second, for P = V,
N or T, it was required that |P-<P>| > k * <P>, where k = 0.1 for
P = V and k = 0.3 if P = N or T.  For P = Vx, Vy, or Vz, the
second condition was that |P-<P>| > 0.1 * <V>.   If a spike was
found in any parameter, that record was eliminated.
In the ~4,000,000 records in the MIT files that were tested, 
some 20,000-40,000 spikes were found.  Since some records had multiple
spikes, the fraction of records eliminated by our spike finder was <1%.

Even after having applied this spike finder software and after
the prior application of spike finder software at MIT, many suspicious
points remained.  Accordingly, we viewed plots of all data and
identified suspicious points.  We then examined each.  A subset of
these points (<300 points in all, some isolated and some grouped) 
was removed from the final data files now in this directory.  

 The contents/format of records are:

Wd Format  Fill values      Parameters
 1  I5     9999             Year
 2  F12.6  99999.9999999    Decimal Day (day.fractionofday)
 3  F8.1   99999.9          Flow Speed, km/s
 4  F8.1   99999.9          Vx, GSE, km/s, flow velocity component
 5  F8.1   99999.9          Vy, GSE, km/s
 6  F8.1   99999.9          Vz, GSE, km/s
 7  F9.0   9999999.         Proton Temperature, K.
 8  F7.2   999.99           Proton Density, n/cc
 9  F6.3   9.999            Alpha/protom ratio (all fill) 
10  F8.2   9999.99          X, GSE,Re, spacecraft position vector
11  F8.2   9999.99          Y, GSE,Re
12  F8.2   9999.99          Z, GSE,Re
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Note: As 05/2016 SWE Trajectory ( words 10-12) were corrected by data taken from SSCWeb site
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Related data and directories:
SPDF Data and Orbits Services <http://spdf.gsfc.nasa.gov/>

SPDF Contact: Natalia Papitashvili <Natalia.E.Papitashvili@nasa.gov>,


Please acknowledge NASA's Space Physics Data Facility, for data usage.

Authorizing NASA Official: Dr. R.E. McGuire, Head, SPDF, NASA Goddard Space Flight Center
                        301-286-7794, e-mail:  Robert.E.McGuire@nasa.gov

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