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Level 2A XPS

SEE Level 2A XPS Solar Irradiance Data

Download multiple days from the TIMED MDC

XPS Calendar Access: Useful for finding data for a specific day.

2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017

XPS Level 2A Data Directory – download any data file

Detailed Level 2A XPS Description

README_XPS_L2A_012.TXT – information for using XPS_L2A data

The 12 X-Ray Photometers (XP) aboard SEE perform full-disk irradiance measurements of the Sun for about 3 minutes every orbit (97 minutes) which usually gives 14-15 measurements per day. 8 of the XPs produce XUV signals (more info on XP coatings) and one other XP provides a hydrogen Lyman-alpha measurement (121.5 nm). The XPS Level 2A data is time averaged over each measurement, after being 1-AU corrected and removing flares. The 1-AU correction is provided.


Channel Coating Low Wavelength (nm) High Wavelength (nm)
1 Ti/C-14 0.10 7.00
2 Ti/C-10 0.10 7.00
3 Al/Sc/C-24 17.00 23.00
5 Ti/Pd-17 0.10 10.00
6 Ti/Zr/Au-04 0.10 10.00
7 Al/Nb/C-03 17.00 21.00
9 Al/Mn-06 0.10 7.00
10 Cr/Al-07 0.10 7.00
11 Ly-alpha 121.00 122.00

After day 205 of 2002 only the green highlighted channels ( 1, 5, & 10) continue to provide XUV signal due to a filter wheel anomaly.

XPS Sensitivity Data from the Bessy calibration

Reading the Data with IDL

With individual data files may be read using an IDL command such as:


The data will then reside in the returned structure “d”, with each tag in the structure defined in the attributes array “att”. Each of the 9 coated diodes used to produce the X-Ray irradiances have a band pass range in the wave array tag.

SEE Level 2A XPS Software

  • TIMED-SEE NetCDF README – Described IDL source code and gives examples using and
  • – IDL procedure for reading NetCDF files as a structure
  • – IDL procedure for writing a data structure (or array of structures) to a NetCDF file
  • – IDL procedure for plotting a time series of XPS Level 2A data.

SEE Level 2A XPS Solar Irradiance Data Format

Each data file contains an array of structures with 53 elements


L2A_XPS_DATA    STRUCT    = ->  Array[53]

Each L2A_XPS_DATA structure has the following form:


** Structure <279b28>, 16 tags, length=64, data length=59, refs=1:
   DATE            LONG           2002022
   CHANNEL         INT              1
   WAVE            FLOAT     Array[2]
   FLUX_MEDIAN     FLOAT       0.000862951
   DIFF_MA         FLOAT           0.00000
   ERR_TOT         FLOAT          0.163683
   ERR_MEAS        FLOAT         0.0124845
   STDEV_MEAS      FLOAT         0.0124845
   COR_1AU         FLOAT           1.03242
   CURRENT         FLOAT          0.452243
   NUMPT           INT              1
   QUALITY_FLAGS   INT              1
   ODC_ID          BYTE         4
   START_TIME      FLOAT           18585.1
   STOP_TIME       FLOAT           18688.0
   FLARE           FLOAT          0.985123


NetCDF file attributes for day 2002022



    Title = SEE Level 2A XPS Data Product - calibrated XPS data averaged over
      each observation

    Source = SEE POC at LASP / CU

    Mission = TIMED

    Data_product_type = SEE XPS Level 2A

    Data_product_version = 011

    Data_product_revision = 01

    Product_format_version = 010

    Software_version = 11.01

    Software_name = called from

    Calibration_version = 09.01

    Description = Calibrated SEE XPS science data averaged over an observation
      $ at instrument resolution with degradation, atmospheric, and 1AU corrections

    History = 10/8/02 DLW Added product_format_version $ 2/17/03 DLW Added

    Filename =

    Date_generated = Tue Oct  4 16:36:42 2011


    Units = YYYY-DOY

    Description = Date of observation


    Units = none

    Description = Channel index of the 12 XUV Photometers (1-12)


    Units = nm

    Description = Bandpass wavelength range


    Units = W / m^2

    Description = Solar irradiance - median for the day


    Units = W / m^2

    Description = Difference of median and weighted average solar irradiance over
      the day


    Units = Fractional

    Description = Accuracy of solar irradiance averaged over the day


    Units = Fractional

    Description = Measurement precision averaged over the day


    Units = Fractional

    Description = Standard deviation of median for good measurements


    Units = 1 / (AU^2)

    Description = AU correction factor for date


    Units = nanoAmps

    Description = Median of Total-Dark-Visible currents from level 1 with FOV
      and 1-AU corrections applied


    Units = none

    Description = Number of measurements used in daily average


    Units = none

    Description = 0 means XPS measures flux greater than 3-sigma above the GOES
      XRS long channel correlation, 1 means the XPS is within 3-sigma of the expected
      value, 2 is indeterminate due to a lack of available GOES long channel 
      correlation data


    Units = none

    Description = Memory address of command, valid from 1-254


    Units = Seconds

    Description = UT time in seconds of day for start integration used in


    Units = Seconds

    Description = UT time in seconds of day for the end integration used in


    Units = none

    Description = Ratio of observation flux_median to daily flux_median