This page contains a few applications using 4A/OP. 4A/OP processing is controlled by a set of global variables that identify required input data files and a file of run parameters. The user defines these variables through a script file or a Graphical User Interface (GUI).
- Input data include algorithm fixed and user data.
Algorithm fixed input data provide information for:
- Optical thickness atlases
- Reference thermodynamical parameters used for the computation of atlases
- Default gas mixing ratio
User input data are:
- Atmospheric profiles (on user-defined pressure levels)
- Instrumental functions if it is necessary
Interferometer / spectrometer examples
- Simulation definition parameters
- Spectral conditions
- Observation configuration
- Output data depend on the simulation case.
- High resolution spectra (radiances and brightness temperatures)
- Convolved spectra (radiances and brightness temperatures)
- Jacobians on user-defined pressure layers (partial derivatives of the radiance with respect to the temperature, the gas mixing ratio and the surface emissivity)
- Transmittances on user-defined pressure layers
The examples provide illustrations of both the input and output files. See the content of each input file for a description of simulation definition parameters. We present several examples of how to use 4A/OP.
As a first example, here is the high-resolution radiance (in equivalent brightness temperature) computed from 719 to 721 cm-1 for five TIGR standard profiles (see figures 1 and 2). The results are shown in figure 3. Figure 4 displays the same simulation conditions but for another spectral domain. Click here to see the input parameter file corresponding to the first spectral domain.
The second example is the computation of the convolved radiance (in equivalent brightness temperature) that would be measured by the instrument IASI (Figure 5), from 850 to 900 cm-1, and by HIRS (Figure 7) from 750 to 1000 cm-1. The corresponding Jacobians with respect to the temperature for IASI are illustrated in Figure 6. Click here to see the input parameter file corresponding to IASI.