README file for: ---------------- TIMED SEE XPS Level 4 Model Products This README file is located at: https://lasp.colorado.edu/data/timed_see/level4/README_SEE_L4_011.TXT One should 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 XPS Level 4 Model Products -------------------------------------------------- SEE XPS Level 4 OVERVIEW: ------------------------ The Solar EUV Experiment (SEE) XUV Photometer System (XPS) measures the solar irradiance in the X-ray Ultraviolet (XUV) wavelength range from approximately 0.1 to 34 nm and at Lyman-alpha at 121.6 nm. The XPS has 9 XUV photometers with each having a bandpass of 6-11 nm and 3 visible photometers for the in-flight calibration of the window transmission. Details of the SEE instrument are given by Woods et al. 2005 [J. Geophys. Res., 110, A01312, doi: 10.1029/2004JA010765, 2005] and can also 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 XPS Level 4 data are derived from the XPS Level 1 Data Products. The XPS Level 4 processing algorithm uses reference CHIANTI spectral models to generate a higher spectral resolution (0.1 nm) estimate of the solar XUV irradiance by scaling the model reference spectra to match the XPS photometer currents (signal). The CHIANTI Quiet Sun (QS) spectrum and Active Region (AR) spectrum are used with a scaling of the AR spectrum to match the minimum signal on each day, and then a CHIANTI isothermal flare spectrum is scaled to match the signal above the daily minimum signal. The flare temperature is determined from the ratio of the GOES XRS 0.1-0.8 nm irradiance to the GOES XRS 0.05-0.4 nm irradiance. These scaling factors, flare temperature, and resulting model spectrum in the 0-40 nm range in 0.1 nm intervals are in the XPS Level 4 data product for every measurement made by XPS photometer #1 or #2 (0.1-7 nm band). The details of this algorithm are published in Woods, T. N., and 11 co-authors, XUV Photometer System (XPS): Improved irradiance algorithm using CHIANTI spectral models, Solar Physics, 249, doi 10.1007/s11207-008-9196-6, 2008. New to Version 11 is a change from the CHIANTI QS and AR reference spectra to QS and AR reference spectra derived from SDO EVE in the 6-40 nm range. The spectra in the 0-7 nm range and also for flares are still the CHIANTI spectral models. A SEE XPS Level 4 Model Product is produced for each UT day, and these daily products are also merged into three different full mission data files: 1) daily averages (24-hour) 2) orbit averages (3-min about every 97 min) 3) 1-minute averages (but with only about 3% duty cycle) The XPS Level 4 result in 0.1 nm intervals is also compressed into 1-nm intervals for use in the SEE Level 3 and Level 3A Data Products. On-orbit instrument characterization is an ongoing effort, and the SEE team checks photometer degradation using redundant channels and underflight calibration rockets whose payload includes TIMED SEE prototype instruments. The accuracy of the XPS Level 1 irradiance is 12%-26%, photometer dependent. There is additional uncertainty for applying the spectral model for the XPS Level 4 irradiances, and this estimated accuracy is 30% for the integrated XUV irradiance. The spectral distribution in the XPS Level 4 is from the CHIANTI model and not from direct measurements from XPS, a set of broadband photometers. The spectral distribution above 27 nm has been validated with the TIMED SEE EGS (27-194 nm, 0.4 nm resolution) measurements, so there is good confidence in the spectral distribution shortward of 27 nm. DATA LOCATION: -------------- SEE FTP site is at https://lasp.colorado.edu/data/timed_see/level4/ 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. A special mission-to-date merged file is created from the daily data and updated daily. The most recent file may be located at: https://lasp.colorado.edu/data/timed_see/level4/ with a naming convention of xps_L4_merged_YYYYDOY_011.ncdf FILE FORMAT: ------------ NetCDF file FILE CONTENT: ------------- Solar irradiance in the 0-40 nm range gridded into 0.1-nm intervals on 0.05 nm centers. FILE NAMES: ----------- The XPS Level 4 file naming convention are: xps_L4_YYYYDOY_011.ncdf ; 1-day file see_xps_L4_merged_YYYYDOY_011.ncdf ; full mission merged - daily averages see_xps_L4A_merged_YYYYDOY_011.ncdf ; full mission merged - orbit averages see_xps_L4M_merged_YYYYDOY_011.ncdf ; full mission merged - 1-min averages CURRENT VERSION: ---------------- CURRENT VERSION: 11 (released 10/12) WARNINGS: --------- The XPS Level 4 Model Product includes spectral models, not measurements, one must use caution in interupting any single emission feature. The models are scaled to match the XPS signal, so the Level 4 data integrated over broad bands (5-10 nm or more) are consequently more accurate than individual emissions. See the SEE_v11_releasenotes.txt for more details about the SEE data quality. 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,'xps_L4_2002039_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 -------------------------------------------------- Special Software for XPS Level 4 Model Products -------------------------------------------------- PLOT_XPS4.PRO -------------- This procedure will plot a time series (TS) for a specified wavelength range. This procedure uses the full mission merged data files. IDL> plot_xps4, [0,7] ; plots the integrated 0-7 nm irradiance IDL> plot_xps4, [0,7], /day ; plot using daily averages IDL> plot_xps4, [0,7], /orbit ; plot using orbit averages IDL> plot_xps4, [0,7], /min ; plot using 1-min averages plot_xps4.pro can be found at https://lasp.colorado.edu/data/timed_see/level4/plot_xps4.pro -------------------------------------------------- Version History for SEE Level 4 Model Product -------------------------------------------------- 9.00 4/07 First release of the SEE XPS Level 4 Model Products 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