ABSTRACT - DRUM - University of Maryland

work by Dessler [2002], who used O 3 and CO as tracers of convection to show that
significant detrainment was occurring near the tropopause, at potential temperatures
well above those found in the boundary layer.
3.5 Total height calculation
In the previous section, the overshooting heights of convective clouds were
estimated. If we also estimate the height of the anvil, it is possible to estimate the total
height, which is the sum of the anvil height and the overshooting height. A simple
adiabatic calculation can help estimate the height of the anvil. The temperature at 14
km, the base of the TTL, is very close to that predicted by a moist adiabat rising from
the surface. This is consistent with the fact that 14 km is approximately the upper limit
of the LNB for deep convection. Thus, for altitudes near 14 km, we can use an
adiabatic temperature profile to convert temperature to altitude.
To perform this calculation, two sources of error should be considered. First, this
adiabatic temperature-altitude conversion is a little sensitive to the change of the
surface temperature and the relative humidity (Fig. 3.8). Combined with the individual
overshooting height errors discussed above, it can cause an error of 3-4 km in the total
height calculation in our analysis. Second, because it is doubtful that the temperature at
any level above 14 km could be colder than an adiabat, using the adiabatic altitude
calculation provides a lower limit of the altitude, which implies a potential low bias in
height. Figure 3.8 shows the total height calculated using the 2.5° × 2.5° NCEP
59