PBLH devt1: Threshold for strength of local min/max in PBLH

[Ian Culverwell]

Do we need to set a threshold on the 'strength' of the extremum of dfield/dz, whose location defines the PBLH? Currently any local min/max will qualify, with occasionally unsatisfactory results, eg PBLH_T or PBLH_Tdry2 in prof D of RSR24 (Fig 3.5). Investigate.

(A subticket of #353, really.)

[Ian Culverwell]

Feiqin Xie's ROPP9 beta review suggests adding Ao et al's sharpness parameter (1) to the PBLH output

sharp(X) = max (|dX/dz|) / rms(dX/dz)

where both statistics are computed over the 'valid' range of z, h_min to h_max.

(1) Ao, C. O., D. E. Waliser, S. K. Chan, J.-L. Li, B. Tian, F. Xie, and A. J. Mannucci: Planetary boundary layer depths from GPS radio occultation profiles, J. Geophys. Res., 117, D16117, doi:10.1029/2012JD017598, 2012. (​http://onlinelibrary.wiley.com/doi/10.1029/2012JD017598/pdf)

Sounds like a good idea.

[Ian Culverwell]

Deferred to ROPP10.0.