scholarly journals Ceilometers as planetary boundary layer height detectors and a corrective tool for COSMO and IFS models

2020 ◽  
Vol 20 (20) ◽  
pp. 12177-12192
Author(s):  
Leenes Uzan ◽  
Smadar Egert ◽  
Pavel Khain ◽  
Yoav Levi ◽  
Elyakom Vadislavsky ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Planetary Boundary Layer ◽  
Small Scale ◽  
Transform Method ◽  
Pollution Dispersion ◽  
Boundary Layer Height ◽  
Scale Modeling ◽  
Richardson Method ◽  
Parcel Method

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.

scholarly journals Ceilometers as planetary boundary layer detectors and a corrective tool for ECMWF and COSMO NWP models

2019 ◽  
Author(s):  
Leenes Uzan ◽  
Smadar Egert ◽  
Pavel Khain ◽  
Yoav Levi ◽  
Elyakom Vladislavsky ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Air Pollution ◽  
Planetary Boundary Layer ◽  
Weather Prediction ◽  
Efficient Tool ◽  
Height Difference ◽  
Transform Method ◽  
Mean Error ◽  
Richardson Method ◽  
Parcel Method

Abstract. 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 m, RMSE = 97 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 m, RMSE = 203 m) and elevated terrain (mean error = −6 m, RMSE = 251 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.

scholarly journals Planetary Boundary Layer Height Estimates From ICESat-2 and CATS Backscatter Measurements

2021 ◽  
Vol 2 ◽  
Author(s):  
Stephen P. Palm ◽  
Patrick Selmer ◽  
John Yorks ◽  
Stephen Nicholls ◽  
Edward Nowottnick
Keyword(s):  
Boundary Layer ◽  
Planetary Boundary Layer ◽  
Climate Modeling ◽  
Weather Prediction ◽  
Regional Variability ◽  
Pollution Dispersion ◽  
Boundary Layer Height ◽  
Ice Cloud ◽  
Height Estimates ◽  
Complex Interactions

The lowest layer of the atmosphere in which all human activity occurs is called the Planetary Boundary Layer (PBL). All physical interactions with the surface, such as heat and moisture transport, pollution dispersion and transport happen in this relatively shallow layer. The ability to understand and model the complex interactions that occur in the PBL is very important to air quality, weather prediction and climate modeling. A fundamental and physically important property of the PBL is its thickness or height. This work presents two methods to obtain global PBL height using satellite lidar data from the Ice, Cloud and land Elevation Satellite-2 (ICESat-2) and the Cloud-Aerosol Transport System (CATS). The first method is a straightforward backscatter threshold technique and the second is a machine learning approach known as a Convolutional Neural Network. The PBL height retrievals from the two methods are compared with each other and with PBL height from the NASA GEOS MERRA-2 reanalysis. The lidar-retrieved PBL heights have a high degree of spatial correlation with the model heights but are generally higher over ocean (∼400 m) and over northern hemisphere high latitude regions (∼1,000 m). Over mid-latitude and tropical land areas, the satellite estimated PBL heights agree well with model mid-day estimates. This work demonstrates the feasibility of using satellite lidar backscatter measurements to obtain global PBL height estimates, as well as determining seasonal and regional variability of PBL height.

The Growth of the Planetary Boundary Layer at a Coastal Site: a Case Study

2011 ◽  
Vol 139 (3) ◽  
pp. 521-541 ◽  
Author(s):  
Ferdinando De Tomasi ◽  
M. Marcello Miglietta ◽  
M. Rita Perrone
Keyword(s):  
Boundary Layer ◽  
Planetary Boundary Layer ◽  
Coastal Site

scholarly journals Observed Diurnal Cycle Climatology of Planetary Boundary Layer Height

2010 ◽  
Vol 23 (21) ◽  
pp. 5790-5809 ◽  
Author(s):  
Shuyan Liu ◽  
Xin-Zhong Liang
Keyword(s):  
Boundary Layer ◽  
Planetary Boundary Layer ◽  
Diurnal Cycle ◽  
Surface Characteristics ◽  
Planetary Boundary Layer Height ◽  
Layer Height ◽  
Boundary Layer Height ◽  
Tropical Oceans ◽  
Critical Model ◽  
Fine Resolution

Abstract An observational climatology of the planetary boundary layer height (PBLH) diurnal cycle, specific to surface characteristics, is derived from 58 286 fine-resolution soundings collected in 14 major field campaigns around the world. An objective algorithm determining PBLH from sounding profiles is first developed and then verified by available lidar and sodar retrievals. The algorithm is robust and produces realistic PBLH as validated by visual examination of several thousand additional soundings. The resulting PBLH from all existing data is then subject to various statistical analyses. It is demonstrated that PBLH occurrence frequencies under stable, neutral, and unstable regimes follow a narrow, intermediate, and wide Gamma distribution, respectively, over both land and oceans. Over ice all exhibit a narrow distribution. The climatological PBLH diurnal cycle is strong over land and oceans, with a distinct peak at 1500 and 1200 LT, whereas the cycle is weak over ice. Relative to midlatitude land, the PBLH variability over tropical oceans is larger during the morning and at night but much smaller in the afternoon. This study provides a unique observational database for critical model evaluation on the PBLH diurnal cycle and its temporal/spatial variability.

Comparison between two algorithms based on different wavelets to obtain the Planetary Boundary Layer height

2014 ◽  
Author(s):  
Gregori de Arruda Moreira ◽  
Fabio J. da Silva Lopes ◽  
Juan L. Guerrero-Rascado ◽  
Maria José Granados-Muñoz ◽  
Riad Bourayou ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Planetary Boundary Layer ◽  
Planetary Boundary Layer Height ◽  
Layer Height ◽  
Boundary Layer Height
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