Abstract. Active remote-sensing instruments, such as ceilometers, have been shown to be potentially useful for the investigation of the behavior of the atmospheric mixing layer height (MLH). For the first time ever, high-resolution measurements of backscatter intensity, taken from two CL31 ceilometers situated inland and onshore of Israel, have enabled evaluation of the mean diurnal cycle of the MLH in the eastern Mediterranean region. Although the Israeli summer synoptic conditions are considered to be quite stable, results for the summer season (July-August 2014) showed the inland MLH to be about 200 m higher than the MLH at the onshore site, situated only 7.5 km away. The prevailing influence of the sea breeze front (SBF), as it progresses inland, is presented by the ceilometer plots. Complementing results were found between the radiosonde profiles and the adjacent ceilometer at the inland site of Beit Dagan. In contrast to the expected regularity of clear skies during the Israeli summer, the ceilometers revealed significant cloud cover throughout the day, with higher presence onshore. Assessment of cloud thickness in further research would serve to improve the evaluation of the MLH evolution.
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.
Abstract. On 7 September 2015, an unprecedented and unexceptional extreme dust storm struck the eastern Mediterranean (EM) basin. Here, we provide an overview of the previous studies and describe the dust plume evolution over a relatively small area, i.e., Israel. This study presents vertical profiles provided by an array of eight ceilometers covering the Israeli shore, inland and mountain regions. We employ multiple tools including spectral radiometers (Aerosol
<p><strong>Abstract.</strong> The growing importance of the planetary boundary layer (PBL) height detection is apparent in various fields, from air pollution analysis to weather prediction. In recent years micro-lidars such as ceilometers have been recognized as an efficient tool for such measurements. Here, the daytime summer PBL height is measured by eight ceilometers throughout Israel, along with with radiosonde profiles, the global IFS model, and the regional COSMO model. The analysis focused on three PBL height evaluation methods: the bulk Richardson method, the parcel method, and the wavelet covariance transform method. The best agreement between the PBL heights derived from a single radiosonde site on 33 summer days was found by the adjacent ceilometer (mean error = 12&#8201;m, RMSE = 97&#8201;m). Spatial analysis of the PBL heights derived from the models on 13 days in reference to five ceilometer measurement sites revealed COSMO evaluations by the bulk Richardson method (COSMOR) produced the best results for both flat (mean error = 19&#8201;m, RMSE = 203&#8201;m) and elevated terrain (mean error = &#8722;6&#8201;m, RMSE = 251&#8201;m). To improve COSMOR results, a regression tool was assimilated based on the PBL height difference between COSMOR and ceilometers. The regression is based on the altitude and distance from the shoreline for eight ceilometer sites.</p>
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