Date: 21 August  2024


Dataset Title: NASA CRRES Plasma Wave Density Data


Dataset Creators: M. B. Moldwin 


Dataset Contact: Mark Moldwin mmoldwin@umich.edu

Funding: NASA


Key Points:
- Electron density data obtained by the CRRES Plasma Wave Experiment of Anderson et al. (1992). 
- Data extracted from PWE survey plots by Don Carpenter (Stanford University) (https://space.physics.uiowa.edu/plasma-wave/crres/)
- Data used in a variety of studies of the plasmasphere and plasmapause. 


Research Overview:
CRRES electron density data from the time period August 19, 1990 to October 12, 1991 is provided from PWE onboard CRRES. The data provides information about the inner magnetospheric cold plasma density of the plasmasphere and trough region. It has been used to identify the plasmapause and create models of the electron density.




Methodology:
The database was developed by tracing the upper hybrid resonance (UHR) frequency on spectrograms. The UHR is the sum of the plasma frequency and the cyclotron frequency. Using the simultaneously measured magnetic field to estimate the cyclotron frequency, the plasma frequency can be determined. The plasma frequency is directly proportional to the electron number density. The tracing was done by Don Carpenter of Stanford and Roger Anderson of University of Iowa. 


Instrument and/or Software specifications: NA


Files contained here:

The two zip folder CRRES_density and CRRES_ephem contain individual orbit files of the electron number density data (including the UHR, FCE and FPE) and the location of the CRRES spacecraft in magnetic coordinates including mapping to the McIlwain L-Value.

ORBXXX.DEN: XXX denotes the orbit number of CRRES.

The first header row contains the filename, date, and the instrument PI's name.

Columns in this file are:

VTCW     YRDOY HR:MN:SS  FCE(KHZ) FUHR(KHZ)  FPE(KHZ) NE(CM**-3) ID     M

Where VTCW is vehicle time code word (VTCW). The VTCW has a resolution of 128 ms and a
rollover of about 2.18 years; YRDOY is Year and Day of Year; HR:MN:SS is the hour, minute and second UTC; FCE (KHZ) is the electron cyclotron frequency in kiloHertz; FUHR (KHZ) is the Upper Hybrid Frequency in kiloHertz; FPE (KHZ) is the electron plasma frequency in kiloHertz; NE (CM**-3) is the electron number density in particles per cubic centimeter; ID M describes the band and mode used in the instrument. See Anderson et al., 1992 for description of how the different frequency bands were handled.

EPHXXX.DAT XXX denotes the orbit number of CRRES.

The first header row contains the filename and description of the file (Ephemeris Data)

Columns in this file are 

       Time         GM     gmLT   Radius  Magnetic       
yyyy ddd hh:mm:ss   Lat  hh:mm:ss  (RE)   FldStrth  L-Val

Where Time is given as four digit year (yyyy), day of year (ddd), geomagnetic latitude (GM Lat); geomagnetic Local Time (gmLT) in hours:minutes:seconds (hh:mm:ss), distance from the center of the Earth (Radius) in units of Earth Radii (RE); the magnetic field strength (Magnetic FldStrth) in units of nT; and the L-Value (L-Val)


Related publication(s):

CRRES Plasma Wave Experiment, R.R. Anderson, D.A. Gurnett, and D.L. Odem, J. Spacecraft & Rockets, 29, August 1992. 

Sheeley, B. W., M. B. Moldwin, H. K. Rassoul, and R. R. Anderson (2001), An empirical plasmasphere and trough density model: CRRES observations, J. Geophys. Res., 106(A11), 25631–25641, doi:10.1029/2000JA000286.

Use and Access: 
This data set is made available under a Creative Commons Public Domain license (CC0 4.0).


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