PBLH devt2: Revise setting of max PBLH

[Ian Culverwell]

Do we need to set max PBLH = 5000 m - surface height (eg over Antarctica)? Currently, 5000 m AGL in Antarctica = 8000 m ASL, which is where the polar tropopause can be. We don't want to interpret that as a PBLH! On the other hand, in the Sahara (~1000 m ASL), the PBLH can be 5000 m AGL, I think, so we don't want to restrict the max to 4000 m there. Need to ponder this.

(A subticket of #353, really.)

[Ian Culverwell]

The ROPP9.0 beta reviewer says:

It could be useful to include the minimum penetration 
height (h_penet) as a separated input parameter, 
instead of a hard-coded parameter. A slight increase 
the threshold could help increase the useful RO 
soundings for regional studies. For example, a 
threshold of 500 m was used in Xie et al. (2012) over 
subtropical southeast Pacific Ocean. In addition, two 
more input parameters: the minimum and maximum cut-off 
height (e.g., h_min = 300 m, h_max = 5 km) could be 
introduced, which specifies the valid vertical range of 
RO profiles to be used for PBLH derivation. The input 
parameter h_min could be different from h_penet. Also 
it could be very useful to change it to be even less 
than 300 m when trying to identify the surface 
inversion that are often seen over polar regions and 
the nocturnal PBL over land. However, the RO sounding 
quality near the surface is still lack of
understanding and need more studies.

So allow these three heights to be input by users of the PBLH tool.

[Ian Culverwell]

Also investigate the sensitivity of the results to the setting of these parameters. (Note that this rather open-ended piece of work might well be transferred to its own ticket.)

[Ian Culverwell]

Postpone to ROPP10.0.