CTT is not producing result similar to UPP

[bladwig1]

This issue was reported on wrfpython-talk:

https://groups.google.com/a/ucar.edu/forum/#!topic/wrfpython-talk/5D3JgHb0lDI

The CTT algorithm doesn't match UPP very well, and the UPP result looks good.

At first glance, a few issues were found:

• There are some OpenMP private directives that are needed.
• There is no behavior for what happens when the various searches fail.
• Missing values are probably needed, similar to the cloudfrac algorithm.

[bladwig1]

After looking at this more closely, the algorithm works by searching for an optical depth greater than 1.0 for each vertical column in the domain. If the search finds no optical depth (clear sky), then the surface temperature is returned for that column.

I think we can simply add a flag to indicate that the user wants missing/fill values to be returned for these areas instead of surface temperature, but keep the default the same so that backwards compatibility is retained.

The line of code that will need to be modified is:

ELSE IF (opdepthd .LT. 1. .AND. k .EQ. nz) THEN
    prsctt = prs(i,j,1)
    EXIT

Change this to insert a missing value, then later check if it's missing and skip the interpolation for temperature.

[bladwig1]

The OpenMP directive issue will be fixed in 1.1.2. The option to add fill values for no-cloud areas will be released later.

[bladwig1]

There is an indexing bug here:

prsctt = pf(i,j,k-1) + fac*(pf(i,j,k) - pf(i,j,k-1))

There is nothing preventing k from being 1, which is causing Windows to crash, and this is a ticking time bomb for Linux and Mac.

[bladwig1]

Also, the computation is not correctly integrating from top to bottom when using WRF files that do not contain cloud ice mixing ratio.