TIMED SEE

SEE Level 2A XPS Solar Irradiance Data

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Detailed Level 2A XPS Description

README_XPS_L2A_011.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.

ChannelCoatingLow Wavelength (nm)High Wavelength (nm)
1Ti/C-140.107.00
2Ti/C-100.107.00
3Al/Sc/C-2417.0023.00
5Ti/Pd-170.1010.00
6Ti/Zr/Au-040.1010.00
7Al/Nb/C-0317.0021.00
9Al/Mn-060.107.00
10Cr/Al-070.107.00
11Ly-alpha121.00122.00
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

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Reading the Data with IDL

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

read_netcdf,'see__xps_L2A_2002022_005_01.ncdf',d,att
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.

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SEE Level 2A XPS Software

  • TIMED-SEE NetCDF README - Described IDL source code and gives examples using read_netcdf.pro and write_netcdf.pro
  • read_netcdf.pro - IDL procedure for reading NetCDF files as a structure
  • write_netcdf.pro - IDL procedure for writing a data structure (or array of structures) to a NetCDF file
  • plotxps_ts.pro - IDL procedure for plotting a time series of XPS Level 2A data.
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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 <2e3518>, 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

GLOBAL:

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 = write_netCDF.pro called from xps_level2_main.pro
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 diff_ma.
Filename = /titus/timed/testing/data/science_dp/level2a_xps/xps_L2A_2002022_011_01.ncdf
Date_generated = Tue Oct 4 16:36:42 2011
DATE:
Units = YYYY-DOY
Description = Date of observation
CHANNEL:
Units = none
Description = Channel index of the 12 XUV Photometers (1-12)
WAVE:
Units = nm
Description = Bandpass wavelength range
FLUX_MEDIAN:
Units = W / m^2
Description = Solar irradiance - median for the day
DIFF_MA:
Units = W / m^2
Description = Difference of median and weighted average solar irradiance over the day
ERR_TOT:
Units = Fractional
Description = Accuracy of solar irradiance averaged over the day
ERR_MEAS:
Units = Fractional
Description = Measurement precision averaged over the day
STDEV_MEAS:
Units = Fractional
Description = Standard deviation of median for good measurements
COR_1AU:
Units = 1 / (AU^2)
Description = AU correction factor for date
CURRENT:
Units = nanoAmps
Description = Median of Total-Dark-Visible currents from level 1 with FOV and 1-AU corrections applied
NUMPT:
Units = none
Description = Number of measurements used in daily average
QUALITY_FLAGS:
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
ODC_ID:
Units = none
Description = Memory address of command, valid from 1-254
START_TIME:
Units = Seconds
Description = UT time in seconds of day for start integration used in observation
STOP_TIME:
Units = Seconds
Description = UT time in seconds of day for the end integration used in observation
FLARE:
Units = none
Description = Ratio of observation flux_median to daily flux_median
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      NASA SEE TIMED LASP

Revised: November 2007
+ Questions or comments?