computing lat_tp, lon_tp, azimuth_tp variables

[Huw Lewis]

Helpdesk enquiry 50

Hi,

please could you let me know, which routine has to be called for 
setting the L1btype structure components L1btype%lat_tp(:), 
L1btype%lon_tp(:) and L1btype%azimuth_tp(:).

I have tried to locate such a function/subroutine in the ROPP 
packages and the  ropp_pp_occ_tool.f90 source code, but did not 
find a routine for setting lat_tp(:), lon_tp(:) or azimuth_tp(:).

Response:

At present, the ROPP_PP module does not provide any support for 
calculating lat_tp, lon_tp or azimuth_tp.

These data are however currently provided in the GRAS SAF 'atm' 
files for example.

Routines to enable users to compute these values from the 
occultation geometry (as part of ropp_pp_occ_tool.f90 for example) 
will be included in a future update release.

Need to add calculations of lat_tp, lon_tp and azimuth_tp as part of coordinate calculations in ropp_pp/ropp_utils modules. The OCC routine includes a GPS_Azimuth subroutine which computes azimuth_tp while lat_tp and lon_tp could be extracted from calculation of the occultation point.

[Huw Lewis]

A new tangent_point() routine has been added to the ropp_utils/coordinates/ library. See [2467].

This computes azimuth_tp, lat_tp and lon_tp arrays based on the computations used to find the occultation point. The output are written to the Lev1a data structure on output in the ropp_pp_occ_tool program.

Tested successfully.

Ticket closed as fixed.