A Three-Step Method for Estimating the Mixing Height Using Ceilometer Data from the Helsinki Testbed

Abstract

A new three-step idealized-profile method to estimate the mixing height from vertical profiles of ceilometer backscattering coefficient is developed to address the weaknesses found with such estimates that are based on the one-step idealized-profile method. This three-step idealized-profile method fits the backscattering coefficient profile of ceilometer measurements into an idealized scaled vertical profile of three error functions, thus having the potential to determine three aerosol layers (one for the surface layer, one for the mixing height, and one for the artificial layer caused by the weakened signal). This three-step idealized-profile method is tested with ceilometer and radiosounding data collected during the Helsinki Testbed campaign (2 January 2006-13 March 2007). Excluding cases with low aerosol concentration in the boundary layer, cases with clouds present, and cases with precipitation present, the resulting dataset consists of 97 simultaneous backscattering coefficient profiles and radiosoundings. The three-step method is compared with the one-step method and other commonly employed algorithms. A strong correlation (correlation coefficient r 5 0.91) between the mixing heights as determined by the three-step method using ceilometer data and those determined from radiosoundings is an improvement over the same correlation using the one-step method (r 5 0.28), as well as the other algorithms.

Quantifying the relationship between PM<sub>2.5</sub> concentration, visibility and planetary boundary layer height for long-lasting haze and fog–haze mixed events in Beijing

“…Ceilometer is a robust, low-power, low-cost and lowmaintenance lidar designed to determine the cloud base height but also provide the backscatter profile, though with less sensitivity than a lidar. Several studies have proposed that ceilometer-measured backscatter profiles can be used to derive the PBL height (Eresmaa et al, 2006(Eresmaa et al, , 2012Münkel, 2007;Haeffelin et al, 2012;Schween et al, 2014). A "structure of the atmosphere" (STRAT-2D) algorithm was selected for estimating the PBL height, which has been proposed in the literature (Morille et al, 2007;Haeffelin et al, 2012;Wiegner et al, 2014).…”

Application of Convective Condensation Level Limiter in Convective Boundary Layer Height Retrieval Based on Lidar Data

“…The idealized backscatter method [20,49], also known as curve fitting (hereafter fitting), aims to fit a four-parameter ideal profile B(z) to the observed backscatter profile,NRB(z). The ideal profile is expressed as:…”

Mixing-layer height retrieval with ceilometer and Doppler lidar: from case studies to long-term assessment

“…They are based on evaluating the gradient of the backscatter profile (Endlich et al, 1979), its logarithm (i.e. the relative gradient) (Senff et al, 1996), fitting to a function (Steyn et al, 1999;Eresmaa et al, 2012), application of the Haar wavelet analysis (Davis et al, 2000;Brooks, 2003;Haij et al, 2006), or a threshold for the backscatter (e.g. Harvey et al, 2013).…”

“…Even though advantages and disadvantages of different methods have been investigated by several studies (see e.g. Sicard et al, 2006;Haij et al, 2007;Eresmaa et al, 2012;Haeffelin et al, 2012), no consensus on a specific algorithm has been reached yet.…”

“…Several studies have proposed that ceilometer-measured backscatter profiles can be used to derive the MLH (e.g. Münkel et al, 2007;Eresmaa et al, 2006Eresmaa et al, , 2012. Many airports, weather services, research institutions etc.…”