README file for: ---------------- TIMED SEE EGS Level 2B Occultation Data Product This README file is located at: https://lasp.colorado.edu/data/timed_see/level2b_egs_occ/README_EGS_L2B_OCC_011.TXT Also read the SEE_v11_releasenotes.txt file for known issues with the SEE data at: https://lasp.colorado.edu/data/timed_see/SEE_v11_releasenotes.txt -------------------------------------------------- TIMED Data Rules of the Road & Data Access Policy -------------------------------------------------- Users of TIMED data are asked to respect the following guidelines Mission scientific and model results are open to all. Users should contact the PI or designated team member of an instrument or modeling group early in an analysis project to discuss the appropriate use of instrument data or model results. This applies to TIMED mission team members, guest investigators, and other members of the scientific community or general public. Users that wish to publish the results derived from TIMED data should normally offer co-authorship to the PI or his/her designated team member. Co-authorship may be declined. Appropriate acknowledgement to institutions, personnel, and funding agencies should be given. Users should heed the caveats of investigators as to the interpretation and limitations of data or model results. Investigators supplying data or models may insist that such caveats be published, even if co-authorship is declined. Data and model version numbers should also be specified Pre-prints of publications and conference abstracts should be widely distributed to interested parties within the mission and related projects. See also: http://www.timed.jhuapl.edu/scripts/mdc_rules.pl -------------------------------------------------- TIMED SEE EGS Level 2B Occultation Data Product -------------------------------------------------- DIFFERENCES WITH THE LEVEL 2 PRODUCT: The Level 2B data product contains measurements of made by the SEE EGS of atmospheric transmission through the tangent ray point. Note that due to finite and variable instrument precision, this value may exceed 1. Transmissions are calculated by averaging 6-8 transmission measurements and dividing by the average of approximately 20 direct solar measurements from the previous orbit with 20 additional direct solar measurements from the next orbit. Missing data are reported with a value of -1. Note that the processing required to perform this measurement is slightly simpler since certain degradation-related corrections would divide out. Most tangent ray points lie between 50 and 450 km and each orbit providing only one altitude slice at one location. Consecutive orbits provide multiple altitudes, but have different latitude and longitude. Large flares may produce unexpected results. This product is not routinely updated due to relatively few occultation availabilities for SEE. We anticipate approximately 4 updates per year to incorporate additional recent data. New algorithm changes will result in mission-wide reprocessing and the product will then have an incremented version number. EGS OVERVIEW: The EUV Grating Spectrograph (EGS) component of SEE is a 1/4 meter Rowland circle spectrograph with a mechanically-ruled concave grating and a microchannel plate detector with a two-dimensional 1024 x 64 coded anode (CODACON) readout. The EGS covers the wavelength range from approximately 26 to 194 nm. Details of the instrument can be found at https://lasp.colorado.edu/see/overview/instrument-overview For normal operations, SEE observes the Sun for about 3 minutes every orbit (97 minutes), which usually gives 14-15 measurements per day. The SEE EGS Level 2B data are time averaged over about 1 minute. This is near the center time of consecutive direct 3 minute observations. Thermal constraints prevent more frequent measurements during occultation seasons. Seasons occur due to spacecraft-to-sun angle changes, the SEE one-axis pointing platform, and the field of view range of the EGS. DATA LOCATION: SEE FTP site at https://lasp.colorado.edu/data/timed_see/level2b_egs_occ/ Copy the *.ncdf files as BINARY files. Copy the *.pro files (IDL procedures) as ASCII files. Copy the *.txt files (help files) as ASCII files. FILE FORMAT: NetCDF file for the whole mission FILE CONTENT: Atmospheric transmissions from ~26-194 nm gridded onto 1-Angstrom bins. CURRENT VERSION: 11 (released 10/12) See SEE_v11_releasenotes.txt for more information. READING A FILE: You can use the IDL procedure read_netcdf.pro to read the SEE data products (or almost any NetCDF file). Example usage follows. IDL> read_netcdf,'see__egs_L2B_2007115_011.ncdf',d,att where d = data read from the specified file att = string array listing the attributes (definitions) IDL> help, d, /structure ; to list data structure IDL> n = n_elements(att) ; to print attributes IDL> for k=0,n-1 do print, att[k] read_netcdf.pro can be found at https://lasp.colorado.edu/data/timed_see/code/software/idl/netCDF/read_netcdf.pro -------------------------------------------------- Version History for EGS Level 2B Occultation Data Product -------------------------------------------------- 9.00 10/07 First release of this data product. See SEE_v9_releasenotes.txt for information. 10.00 7/09 See SEE_v10_releasenotes.txt for information. 11.00 10/12 See SEE_v11_releasenotes.txt for information. -------------------------------------------------- The main SEE web page is: http://lasp.colorado.edu/see For SEE data access problems or suggestions, you can send e-mail to don.woodraska@lasp.colorado.edu or tom.woods@lasp.colorado.edu -------------------------------------------------- END OF README FILE