Meteorological Analysis Along a Trajectory

Configure the CONTROL file for a trajectory simulation again from Broomfield, Colorado, (39.92N and 105.12W) using the NAM 12 km data. However, this time set the starting height to 1500 m, the Vertical motion data field to 0 (Data), and the Total run time to 84 hours.  The resulting trajectory (right) goes to the southeast into central Texas, decending from 700 hPa to nearly 950 hPa. Note that if you set the Vertical Coordinate to Meters-agl in the Trajectory Display menu, the trajectory actually follows the terrain for the most part, so care must be exercised when interpreting the up or down movement of the trajectories.

If values of selected meteorological variables are desired along the trajectory, a flag in the SETUP.CFG file can be set through the Advanced / Configuration Setup / Trajectory menu tab. Ambient and potential temperature, precipitation, mixing depth, relative humidity, solar radiation, and terrain height are currently the only available options.  One or more fields may be selected and all will be written to the trajectory endpoints file (tdump) as the rightmost columns, however only the rightmost variable (column) can be plotted at the bottom of the trajectory map.

Upon completion of the calculation, the vertical coordinate used to display the trajectory can be selected from the Trajectory Display menu (below, left). Pressure and height are available for all trajectories, potential temperature (theta) is only available for isentropic trajectories, and only the last selected (right-most) meteorological variable can be plotted. In the figure below, right, the bottom graph shows the terrain below the trajectory as it decends into Texas.