TIMED SEE

SEE Level 2 EGS Solar Irradiance Data

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Detailed Level 2 EGS Description

README_EGS_L2_011.TXT - information for using EGS_L2 data

The EUV Grating Spectrograph (EGS) aboard SEE performs measurements of the Sun for about 3 minutes every orbit (97 minutes) which usually gives 14-15 measurements per day. The Level 2 data is time averaged over the entire day, after being 1-AU corrected and removing flares. The 1-AU correction is provided.

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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__egs_L2_2002044_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".

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SEE Level 2 EGS 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
  • plotegs_ts.pro - IDL procedure for plotting a time series of EGS Level 2 data.
  • plotegs_sp.pro - IDL procedure for plotting a daily averaged spectrum from one EGS Level 2 data file.
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SEE Level 2 EGS Solar Irradiance Data Format

Each data file contains a structure with 1 elements

EGS_DATA        STRUCT    = ->  Array[1]

The EGS_DATA structure has the following form:

** Structure <28bef8>, 14 tags, length=98032, data length=98032, refs=1:
DATE LONG 2002039
WAVE FLOAT Array[1690]
FLUX_MEDIAN FLOAT Array[1690]
DIFF_MA FLOAT Array[1690]
ERR_TOT FLOAT Array[1690]
ERR_MEAS FLOAT Array[1690]
STDEV_MEAS FLOAT Array[1690]
NUMPT INT Array[1690]
COR_1AU FLOAT 1.02768
COR_OS_MED FLOAT Array[1690]
COR_OS_AVG FLOAT Array[1690]
DEGRADE_MODEL LONG 0
COR_ATMOS STRUCT -> Array[1]
COR_DEGRADE STRUCT -> Array[1]

Nested structure COR_ATMOS ** Structure <2027138>, 3 tags, length=20280, data length=20280, refs=2:
AVG FLOAT Array[1690]
MIN FLOAT Array[1690]
MAX FLOAT Array[1690]
Nested structure COR_DEGRADE ** Structure <3711e8>, 3 tags, length=20280, data length=20280, refs=2:
AVG FLOAT Array[1690]
MIN FLOAT Array[1690]
MAX FLOAT Array[1690]

NetCDF file attributes for day 2002039

GLOBAL:

Title = SEE Level 2 EGS Data Product - calibrated 0.1nm EGS data averaged over a day
Source = SEE POC at LASP / CU
Mission = TIMED
Data_product_type = SEE EGS Level 2
Data_product_version = 011
Data_product_revision = 02
Product_format_version = 010
Software_version = 11.01
Software_name = write_netCDF.pro called from egs_level2_main.pro
Calibration_version = 09.01
Description = Calibrated SEE EGS science data averaged over a day $ at 0.1 nm bins with degradation, atmospheric, and 1AU corrections
History = 10/8/02 Don Woodraska Added product_format_version. $ 1/28/03 Don Woodraska Added order sorting corrections. $
Filename = /titus/timed/testing/data/science_dp/level2_egs/egs_L2_2002039_011_02.ncdf
Date_generated = Tue Sep 11 19:41:02 2012
DATE:
Units = YYYY-DOY
Description = Date of observation
WAVE:
Units = nm
Description = Array of wavelength intervals, half-Angstrom centers
FLUX_MEDIAN:
Units = W / m^2 / nm
Description = Array of median solar irradiances for each wavelength interval. This is the spectrum
DIFF_MA:
Units = W / m^2 / nm
Description = Array of differences between the median and weighted averaged solar irradiances for each wavelength interval
ERR_TOT:
Units = Fractional
Description = Accuracy of solar irradiance
ERR_MEAS:
Units = Fractional
Description = Measurement precision
STDEV_MEAS:
Units = Fractional
Description = Standard deviation of the median
NUMPT:
Units = NONE
Description = Array of the Number of points (1-Angstrom-gridded measurements) used in determining the daily average for each wavelength interval
COR_1AU:
Units = 1 / (AU^2)
Description = AU correction factor for date
COR_OS_MED:
Units = W/m^2/nm
Description = Order Sorting correction applied to flux_median
COR_OS_AVG:
Units = W/m^2/nm
Description = Order Sorting correction applied to weighted avg irradiance
DEGRADE_MODEL:
Units = None
Description = Long value = 1 if degradation function is linearly extrapolated, 0 if linearly interpolated
COR_ATMOS.AVG:
Units = Fractional
Description = Array of Averaged atmospheric correction factors for each wavelength interval
COR_ATMOS.MIN:
Units = Fractional
Description = Array of Minimum atmospheric correction factors
COR_ATMOS.MAX:
Units = Fractional
Description = Array of Maximum atmospheric correction factors
COR_DEGRADE.AVG:
Units = Fractional
Description = Array of Average instrument degradation correction factors
COR_DEGRADE.MIN:
Units = Fractional
Description = Array of Minimum instrument degradation correction factors
COR_DEGRADE.MAX:
Units = Fractional
Description = Array of Maximum instrument degradation correction factors
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      NASA SEE TIMED LASP

Revised: November 2007
+ Questions or comments?