CHAPTER 4: How to use ?

 
• 4.4 Results files
  • 4.4.1 Overview
  • 4.4.2 Detailed output file description

4.4 Results files

4.4.1 Overview

The following output files might be generated by SCIATRAN:

4.4.2 Detailed output file description

Contains absolute radiance in [photons/s/cm²/nm/sr] (2nd column) versus wavelength in [nm] (1st column) if ``Radiance units'' has been set to ``1'' (see control2.inp) or in [Watt/nm/m²/sr] if ``Radiance units'' is ``2''.

Note: These values are obtained by dividing the sun-normalised intensity by π and multiplying the result with the solar irradiance. The solar irradiance spectrum comes from LOWTRAN7 (default), or from a user supplied solar spectrum (in this case the radiance unit corresponds to the unit of the user supplied solar irradiance times [sr^-1]).

This file will only be created if ``Do radiance in physical units'' has been set to ``true'' in control.inp.

If the Raman (Ring) calculation flag has been set to ``true'' in control.inp, this file will contain a third column containing the radiance with rotational Raman scattering included. In addition, a separate file can be generated containing the Ring spectrum, i.e., the logarithm of the ratio of radiances calculated with and without rotational Raman scattering considered (the default filename is ring.dat).

The weighting functions depend on wavelength and altitude (except for albedo) and express the absolute change in intensity for a relative change of the atmospheric parameters or albedo, for example the ozone concentration at a certain height.

This means, the weighting functions in SCIATRAN are defined as the absolute change in sun-normalised intensity corresponding to a +100% parameter change (assuming linear response). The only exception is the temperature weighting function: it gives the absolute change of sun-normalised intensity per one Kelvin change of the temperature of the corresponding atmospheric layer.

In order to calculate the intensity change resulting from a 100% perturbation of an entire profile (again assuming a linear model) the weighting function values for all layers simply have to be added. The quadrature coefficients (essentially DELTA z) has already been included in the weighting function definition.

This file will only be created if the flag that corresponds to key word ``Do simulation only'' in control.inp has been set to false.

Contains zeros if weighting function calculations of certain components (trace gases, aerosols or albedo) has been switched off in control.inp.

Important note concerning the temperature weighting function: Concerning the temperature weighting function it has to be noted that only the temperature dependence of the air density and the temperature dependence of the ozone absorption cross section is presently into account. The temperature dependence of the absorption cross sections of the other trace gases (e.g. NO₂) has been neglected in the temperature weighting function calculation. This also holds for the line absorbers although the temperature (and also the pressure) strongly affects their absorption cross section.

weightfn.dat contains blocks of weighting functions ordered by wavelength.

For each wavelength weightfn.dat contains one line indicating the wavelength (for example: LAMBDA = 298.0 (nm) followed by the number of atmospheric levels on which the SCIATRAN calculations have been performed, for example, 49. Each of the following lines corresponds to one height level: The first column contains the height index (e.g., 1..49) followed by the corresponding height in [km] followed by 15 columns containing the weighting functions of the trace gases

O₃, NO₂, ClO, OClO, BrO, HCHO, SO₂, NO₃, O₄, O₂, H₂O, CO₂, N₂O, CO, and CH₄.

After one empty line a second set of weighting functions follows. For each atmospheric level one line follows containing the layer index in the first column followed by the corresponding height in [km], followed by the pressure weighting function, followed by the temperature weighting function, followed by the Rayleigh weighting function, followed by 6 columns containing the aerosol weighting functions: the first 3 columns contain the aerosol scattering and the second 3 columns contain the aerosol absorption weighting functions. Each of the 3 columns correspond to one of three wavelength selected for the parameterisation of the aerosol weighting functions (see [38] or [37]).

The aerosol weighting functions have been parameterised using the aerosol scattering and absorption coefficient profiles at three dedicated wavelength (e.g. l₁=200.0 nm, l₂=337.1 nm and l₃=550.0 nm; note: these wavelength have to be specified in control.inp) and assuming linear behaviour in between.

In summary, the structure of each of these lines is as follows:

The line following the pressure, temperature, Rayleigh and aerosol section contains the albedo weighting function (one number for each wavelength).

The last line of the weighting function file contains the end-of-file string ``EOF''.

This file will only be created if ``Do simulation only'' has been set to ``false'' in control.inp.

Contains one column with wavelength in [nm] and 15 columns with airmass factors for all trace gases. The order is the same also used in control.inp and already given above, i.e.

O₃, NO₂, ClO, OClO, BrO, HCHO, SO₂, NO₃, O₄, O₂, H₂O, CO₂, N₂O, CO, and CH₄.

The airmass factors are calculated by calling the main SCIATRAN subroutine
GPP_MASTER twice: first with the relevant trace gas switched on and a second time with this gas switched off.

The airmass factor is defined as follows:

AMF(i,j) := 1 / VOD(i,j) ln[I(i,Gas j = off)/I(i, Gas j = on)]

Note that this file will only be created if ``Do AMF calculation'' has been set to ``true'' in control.inp.

This file has the same structure as tg_amf.dat. It contains the vertical optical depth (optical thickness) for each trace gas. Note that these data have been used to calculate the airmass factors (matrix VOD(i,j), see formula above). This means that multiplying the AMF by the corresponding vertical optical depth gives the ``slant optical depth'', i.e. ln( I^off / I^on ). The temperature dependence of the trace gas absorption cross sections have been taken into account (presently only ozone and NO₂, and all line absorbers).

Note that this file will only be created if ``Vertical optical depth'' has been set to ``true'' in control.inp.

This file contains the vertical depth (optical thickness) due to Rayleigh scattering, the aerosol and cloud scattering and absorption vertical optical depth, and the total (i.e. extinction) optical depth.

The structure of each line is as follows:

Note that this file will only be created if key word ``Vertical optical depth'' has been set to ``true'' in control.inp.

This file contains flux vertical profiles. It will only be created if key word ``Do flux calculations'' has been set to ``true'' in control.inp.

This file contains, for each wavelength, the following information:

The first line of each wavelength segment contains the wavelength in [nm] in the first column and the number of height levels in the second column.

Note that the ``Lower and upper boundary of flux results'' can be specified in control.inp.

For each height level one line follows containing the following information:

The first column contains the height in [km], the second column contains the actinic flux [4] (4 π-integrated radiance; flux through a spherical unit area rather than through a flat unit area as used for the calculation of the up- and downwelling fluxes). Columns 3 and 4 contain the total up- and downwelling fluxes (flux per unit area perpendicular to Earth's surface; 2 π-integrated radiance weighted with the cosine of the zenith angle); columns 5 and 6 also contain up- and downwelling fluxes, but for the diffuse radiance only (i.e. without the contributions from direct sun light).

The unit of the flux values is [radiance units * ster]. The radiance units can be selected in control2.inp; key word: ``Radiance units''.

In summary, the structure of each the lines containing the flux values is as follows:

Contains an overview about the most important input settings.

The complete input settings are contained in the screen output if ``Detailed log file'' has been set to true in control.inp. Otherwise no screen output will be generated.

Error handling:
Apart from some exceptions errors in lower level routines will generate error messages which are stored in errors.log. The lower level routine than immediately returns to the calling routine indicating an error by having set variable error = .true.. This routine also writes an error message until the program is finally stopped in the SCIATRAN main program GT_IFACE.

Note that the SCIATRAN screen output can be switched ``on or off'' using the keyword ``Detailed log file'' in control.inp.