./
stan_bands.pro
top source stan_bands
result = stan_bands(irradiance_ [, wave] [, low=low] [, high=high] [, photons=photons] [, megsa=megsa] [, megsb=megsb] [, l2=l2] [, cal_data_path=cal_data_path])
Given a spectrum and wavelength scale, calculate the "Stan bands"
The "Stan bands" are a set of 22 bands covering the far and extreme ultraviolet spectrum from 0.05nm to 105nm. These bands are used as the input to various Earth atmosphere models. Since the bands are used for the interaction of the ultraviolet with Earth air, some properties of molecular nitrogen must be taken into account. Therefore, several of these bands appear to overlap (bands 11 and 12, 65.0-79.8nm, bands 13-15, 79.8-91.3nm, bands 16-18, 91.3-97.5nm). What is going on with each of these bands is that the band is subdivided into portions where molecular nitrogen absorption is low, medium, or high. Low is a cross section of less than 4 megabarns, medium is between 4 and 31 megabarns, and high is above 31 megabarns. Over these bands, the absorption cross section is very complicated and each band is subdivided into many microbands, each one covering a section of the band where the n2 cross section is all low, medium, or high. All of the microbands in the same cross section category are added together, to get the medium and high (65nm) or low, medium, and high (79.8nm, 91.3nm)
Reference: Solomon, S. C., and L. Qian (2005), 'Solar extreme-ultraviolet irradiance for general circulation models' J. Geophys. Res., 110, A10306, doi:10.1029/2005JA011160
Return value
A 22 element array of irradiance, in each of the Stan bands, in W/m^2 or ph/cm^2/s depending on /photons flag. When there are two overlapping bands, the first is medium cross section and the second is high. When there are three overlapping bands, they are low, medium, and high. If for whatever reason the input spectrum does not support calculating a band, the return value for that band is -1.
Parameters
- irradiance_ in required
Spectrum irradiance, array of irradiance values in w/m^2/nm. As a special case, if irradiance_ is not passed, the function returns immediately, after setting low= and high=. This way, the function can be used to store and recall the band boundaries easily.
- wave in optional
wavelength bin centers, must be an array the same size as irradiance. If not passed, one of /megsa, /megsb, or /l2 must be passed
Keywords
- low out optional
lower bound of each Stan band in nm
- high out optional
upper bound of each Stan band in nm
- photons in optional
If set, return value is in photons/cm^2/s, otherwise result is in W/m^2. Input is in W/m^2/nm regardless.
- megsa in optional
Spectrum uses the native EVE Level 1 MEGS-A wavelength scale. If set, wave is ignored and doesn't need to be passed in
- megsb in optional
Spectrum uses the native EVE Level 1 MEGS-B wavelength scale. If set, wave is ignored and doesn't need to be passed in
- l2 in optional
Spectrum uses the native EVE level 2 spectrum wavelength scale. If set, wave is ignored and doesn't need to be passed in
- cal_data_path in optional
If set, use this path for the cross_sections.dat file. If not set, the program will use $EVE_CAL_DATA if set (in ssw) or the path of the program eve_get_cross_sections.pro if $EVE_CAL_DATA is not set (not ssw).
File attributes
Modification date: | Mon Mar 7 16:29:03 2016 |
Lines: | 125 |
Docformat: | rst rst |