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Agenda ppath_step_agenda
Calculation of a propagation path step. A propagation path step is defined as the path between some point to a crossing with either the pressure, latitude or longitude grid, and this agenda performs the calculations to determine such a partial propagation path. The starting point is normally a grid crossing point, but can also be an arbitrary point inside the atmosphere, such as the sensor position. Only points inside the model atmosphere are handled. The communication between this agenda and the calling method is handled by ppath_step. That variable is used both as input and output to ppath_step_agenda. The agenda gets back ppath_step as returned to the calling method and the last path point hold by the structure is accordingly the starting point for the new calculations. If a total propagation path shall be determined, this agenda is called repeatedly until the starting point of the propagation path is found and ppath_step will hold all path steps that together make up ppath. The starting point is included in the returned structure. The path is determined by starting at the end point and moving backwards to the starting point. The calculations are initiated by filling ppath_step with the practical end point of the path. This is either the position of the sensor (true or hypothetical), or some point at the top of the atmosphere (determined by geometrical calculations starting at the sensor). This initialisation is not handled by ppath_step_agenda. All fields of ppath_step are set by ppath_step_agenda. If the sensor is above the model atmosphere the field *constant* can be initiated by the calling method. Otherwise the field shall be set to negative and it is set to the correct value by ppath_step at the first call. This procedure is needed as the path constant changes if refraction is considered, or not, when the sensor is placed inside the atmosphere. The ppath_step_agenda put in points along the propagation path at all crossings with the grids, tangent points and points of surface reflection. It is also allowed to make agendas that put in additional points to fulfil some criterion, such as a maximum distance along the path between the points. Accordingly, the number of new points of each step can exceed one.
Group: Agenda
Variables
| OUT | ppath_step | (Ppath) | A propagation path step. |
| IN | ppath_step | (Ppath) | A propagation path step. |
| IN | atmosphere_dim | (Index) | The atmospheric dimensionality (1-3). |
| IN | p_grid | (Vector) | The pressure grid. |
| IN | lat_grid | (Vector) | The latitude grid. |
| IN | lon_grid | (Vector) | The longitude grid. |
| IN | z_field | (Tensor3) | The field of geometrical altitudes. |
| IN | r_geoid | (Matrix) | Geoid radius. |
| IN | z_surface | (Matrix) | The surface altitude. |
Specific methods that can generate ppath_step_agenda
- none
Generic and supergeneric methods that can generate ppath_step_agenda
Specific methods that require ppath_step_agenda
- doit_i_fieldUpdate1D
- doit_i_fieldUpdateSeq1D
- doit_i_fieldUpdateSeq1DPP
- doit_i_fieldUpdateSeq3D
- iyBeerLambertStandardClearsky
- iyBeerLambertStandardCloudbox
- iyEmissionStandardClearsky
- iyEmissionStandardClearskyBasic
- mc_IWP_cloud_opt_pathCalc
- MCIPA
- ppathCalc
Generic and supergeneric methods that can use ppath_step_agenda
Agendas that can generate ppath_step_agenda
- none
Agendas that require ppath_step_agenda
- none