%%%% Density Data Files:

	Density data files are available in 3 formats: ascii, matlab, and netcdf. To download, 
	go to http://sisko.colorado.edu/sutton/data.html and click on the year of the desired data 
	under the 'Density' heading. 

	To download the entire year of data, click on the file named 'Density_3deg_yyyy.format.tar.gz', 
	where 'yyyy' is the desired year and 'format' is the desired file format ('ascii', 'mat', or 'nc'). 

	To download one day of data at a time, click on the directory named after the desired format 
	('ascii/', 'matlab/', or 'netcdf/'). In this directory, data files for individual days are 
	named 'Density_3deg_yy_doy.format', where 'yy' is the 2-digit year, 'doy' is the day of the year, 
	and 'format' is the desired file format ('ascii', 'mat', or 'nc').




%%%% Format Description:

	All Density data has been averaged into 3-degree latitudinal bins to conserve space and reduce 
	any random errors. The bins are centered around lat = [-90:3:90] deg, omitting any values 
	for which there are 0 data points in the averaging bin. Neutral density has also been normalized
	to 2 heights (400km and 410km) using the NRL-MSISe-00 Empirical Density Model.




%%%% Ascii Format: 

	Ascii files are arranged in columnn format with a 1-line header of Descriptions 
	including units used) separated by semi-colons (;). The length of the files is 
	approximately 1840 lines.

	Column:			Format:		Description:		Units:
	--------------------------------------------------------------------------------
	[1-2]			2I		Two-digit Year		years
	[4-6]			3I		Day of the Year		days
	[8-15]			8.3F		Second of the Day	GPS time,sec
	[17-19]			3I		Latitude Center of 	deg
						Current Averaging Bin
	[21-29]			9.5F		Geodetic Latitude	deg
	[31-40]			10.5F		Longitude		deg
	[42-48]			7.3F		Satellite Height	km
	[50-56]			7.4F		Satellite Local Time	hours
	[58-66]			9.5F		Quasi-Dipole Latitude	deg
	[68-77]			10.5F		Magnetic Longitude	deg
	[79-85]			7.4F		Magnetic Local Time	hours
	[87-98]			12.6E		Neutral Density		kg/m^3
	[100-111]		12.6E		Density	@ 400km		kg/m^3
	[113-124]		12.6E		Density @ 410km		kg/m^3
	[126-137]		12.6E		NRL-MSIS Density at	kg/m^3
						Satellite Height
	[139-150]		12.6E		Density Uncertainty	kg/m^3
	[152-153]		2I		Number of Data Points 
						in Current Averaging Bin
	[155-156]		2I		Number of Points that
						Require Interpolation
	[158-162]               5.3F		Coefficient of Drag
						Averaged over Bin




%%%% Matlab and Netcdf Format:

	Matlab and Netcdf formats are identical. The variables below are structure arrays 
	containing '.data', '.units', and '.long_name'. For most of the variables, the 
	size of the '.data' structure is n by 1, where n is approximately 1840.

	Variable Name:		Size:		.long_name:		.units:
	--------------------------------------------------------------------------------
	Year.data		1x1		Two-digit Year		years
	Doy.data		1x1		Day of the Year		days
	Sec.data		nx1		Second of the Day	GPS time,sec
	LatBin.data		nx1		Latitude Center of	deg
						Current Averaging Bin
	Lat.data		nx1		Geodetic Latitude	deg
	Lon.data		nx1		Longitude		deg
	Height.data		nx1		Satellite Height	km
	LocTim.data		nx1		Satellite Local Time	hours
	Mlat.data		nx1		Quasi-Dipole Latitude	deg
	Mlon.data		nx1		Magnetic Longitude	deg
	Mlt.data		nx1		Magnetic Local Time	hours
	Density.data		nx1		Neutral Density		kg/m^3
	D400.data		nx1		Density @ 400km		kg/m^3
	D410.data		nx1		Density @ 410km		kg/m^3
	Dmsis.data		nx1		NRL-MSIS Density at	kg/m^3
						Satellite Position
	U_wy.data		nx1		Uncertainty		kg/m^3
	Num.data		nx1		Number of Data Points 
						in Current Averaging Bin
	NumInterp.data		nx1		Number of Points that
						Require Interpolation
	Cd.data			nx1		Coefficient of Drag
						Averaged over Bin


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
These data are placed on this publicly-accessible web site as a service to the community. 
Individuals planning scientific investigations with these data should contact Professor 
Jeffrey M. Forbes at 'forbes@colorado.edu' to verify the status of possible new versions 
of the data, and to arrange coordination and/or collaboration with our ongoing scientific 
activities, as appropriate.

This work is supported by grants from the National Science Foundation (NSF) Space Weather 
Program, the Air Force Office of Scientific Research (AFOSR), and the NASA Graduate 
Student Research Program (GSRP).