Abstract. The significance of planetary boundary layer (PBL) height detection is
apparent in various fields, especially in air pollution dispersion
assessments. Numerical weather models produce a high spatial and temporal
resolution of PBL heights; however, their performance requires validation.
This necessity is addressed here by an array of eight ceilometers; a radiosonde;
and two models – the Integrated Forecast System (IFS) global model and COnsortium
for Small-scale MOdeling (COSMO) regional model. The ceilometers
were analyzed with the wavelet covariance transform method, and the radiosonde
and models with the parcel method and the bulk Richardson method. Good
agreement for PBL height was found between the ceilometer and the adjacent
Bet Dagan radiosonde (33 m a.s.l.) at 11:00 UTC launching time (N=91 d,
ME =4 m, RMSE =143 m, R=0.83). The models' estimations were then
compared to the ceilometers' results in an additional five diverse regions
where only ceilometers operate. A correction tool was established based on
the altitude (h) and distance from shoreline (d) of eight ceilometer sites
in various climate regions, from the shoreline of Tel Aviv (h=5 m a.s.l., d=0.05 km) to eastern elevated Jerusalem (h=830 m a.s.l., d=53 km) and southern arid Hazerim (h=200 m a.s.l., d=44 km). The tool
examined the COSMO PBL height approximations based on the parcel method.
Results from a 14 August 2015 case study, between 09:00 and 14:00 UTC, showed the tool
decreased the PBL height at the shoreline and in the inner strip of Israel by
∼100 m and increased the elevated sites of Jerusalem and Hazerim up to
∼400 m, and ∼600 m, respectively.
Cross-validation revealed good results without Bet Dagan. However, without
measurements from Jerusalem, the tool underestimated Jerusalem's PBL height by
up to ∼600 m.
Ceilometers as planetary boundary layer height detectors and a corrective tool for COSMO and IFS models