Flight track emulator to compare to campaign data

From UKCA

Comparison of UKCA model Simulations with Flight Campaign Data

Comparison of UKCA ozone with data from the first two flights of the INTEX-NA campaign (Singh et al, 2006)).

The UKCA model can be compared to data from campaigns through the use of a flight track emulator. This samples the model at the same time and place as the observations allowing a systematic comparison to be made, especially if the model is being run with nudging. An example of a comparison with the INTEX-NA campaign (Singh et al, 2006)) is shown to the right. The agreement is good between the model and the data, though some discrepancies are caused by using climatological emissions. Documentation for the code is in preparation at the moment (2011).

Using the Flight Emulator

The flight emulator is not part of any standard release as yet, but is part of a development branch (branch fcm:um_br/dev/ptelford/VN7.3_UKCA_CHEM_FASTJX_NADIR @ revision 6051). As the code is fairly standalone it can be cut from this branch and pasted into a branch of your choice. The routines that need copying are in src/atmosphere/UKCA/flight* and the call to the flight main routine from ukca main need adding. The logical flag l_flight also needs adding to include/common/cntlatm.h with the hand edit /home/ptelford/hand_edits/make_flight.ed being used to turn this on.

All that variables that need changing between different flight tracks are set in flight_control.F90. These include

  • flight_infile (input filename)
  • flight_outfile (output filename)

There are then 4 categories of output variables

  • General variables. The number of these is set by nvars. At present this can be 1 or 2. If nvars=1 only temperature is output. If nvars=2 specific humidity is output as well.
  • Tracers. The number of these is set by ntrac (if no tracers are required this should be set to 0). The tracers used are set in the array tracname. Note if the number of tracers used is changed the tracname array needs changing as well.
  • Photolysis rates. The number of these is set by nphot (if no rates are required this should be set to 0). The photolysis rates used are set in the array photname. Note if the number of photolysis rates used is changed the photname array needs changing as well.
  • Mode diagnostics. The number of these is set by nmodediags (if no diagnostics are required this should be set to 0). The diagnostic stash items used are set in the array modediagitem. Note if the number of mode diagnostic items is used is changed the modediagitem array needs changing as well.

Input file

The flight track position is given as a text file containing time, latitude, longitude and pressure. A certain format is expected (although this is easy to change in flight_init.F90). Example files can be found on monsoon and hector at /projects/ukca/ptelfo/um/data/flight_input_example.txt and /work/n02/n02/ptelford/um/data/flight/flight_input_example.txt respectively. The textfile needs to be in the working directory with a name set by flight_control.F90.