Exercise #11

Sensitivity to Gaseous Wet Deposition

  • Load deposit_control.txt and deposit_setup.txt
  • Select gaseous wet deposition defaults in GUI menu
  • Increase Henry's constant to 1.0E+03

Run model and output total deposition

Increase Henry's constant to 1.0E+05

The maximum deposition amount of 3.2E+05 pg/m2 for the particle simulation was not matched by gaseous deposition (4.4E+05 pg/m2) until Henry's constant was increased to 100,000!

Sensitivity to Particle Wet Deposition

Reconfigure for particle wet deposition

Start at 42N 79W on the 26th 0600 for 9 hrs

Rather than the 1 kg, the simulation lost 4 kg when the calculation started in precipitation region because the entire plume extent, in both the horizontal and vertical, was subjected to wet removal.

Sensitivity to Cloud Bottom and Top

Determine which namelist parameters to use

Edit SETUP.CFG with values for RHT and RHB

MESSAGE file results for RHT=60 and RHB=96

Relative humidities that define the extent of the cloud are very sensitive to the grid size of the meteorological model. Threshold values increasingly less than 100% would correspond to the larger grid cell sizes, where not all of the cell contains precipitating clouds. Regardless of the cloud extent definition, wet removal can only occur in grid cells that have a positive precipitation amount.