Evaluation of convective boundary layer height estimates using radars operating at different frequency bands

<p>Knowledge of the atmospheric boundary layer state and evolution is important for understanding air pollution and low-level cloud development, among other things. There are a number of instruments and methods that are currently used to estimate boundary layer height (BLH). However, no single...

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Autores principales:	A. Franck, D. Moisseev, V. Vakkari, M. Leskinen, J. Lampilahti, V.-M. Kerminen, E. O'Connor
Formato:	article
Lenguaje:	EN
Publicado:	Copernicus Publications 2021
Materias:	Environmental engineering TA170-171 Earthwork. Foundations TA715-787
Acceso en línea:	https://doaj.org/article/dcacaef7b2034882b3e246dcb6cba6e5
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spelling	oai:doaj.org-article:dcacaef7b2034882b3e246dcb6cba6e52021-11-24T10:45:34ZEvaluation of convective boundary layer height estimates using radars operating at different frequency bands10.5194/amt-14-7341-20211867-13811867-8548https://doaj.org/article/dcacaef7b2034882b3e246dcb6cba6e52021-11-01T00:00:00Zhttps://amt.copernicus.org/articles/14/7341/2021/amt-14-7341-2021.pdfhttps://doaj.org/toc/1867-1381https://doaj.org/toc/1867-8548<p>Knowledge of the atmospheric boundary layer state and evolution is important for understanding air pollution and low-level cloud development, among other things. There are a number of instruments and methods that are currently used to estimate boundary layer height (BLH). However, no single instrument is capable of providing BLH measurements in all weather conditions. We proposed a method to derive a daytime convective BLH using clear air echoes in radar observations and investigated the consistency of these retrievals between different radar frequencies. We utilized data from three vertically pointing radars that are available at the SMEAR II station in Finland, i.e. the C band (5 GHz), Ka band (35 GHz) and W band (94 GHz). The Ka- or W-band cloud radars are an integral part of cloud profiling stations of pan-European Aerosol, Clouds and Trace Gases Research Infrastructure (ACTRIS). Our method will be utilized at ACTRIS stations to serve as an additional estimate of the BLH during summer months. During this period, insects and Bragg scatter are often responsible for clear air echoes recorded by weather and cloud radars. To retrieve a BLH, we suggested a mechanism to separate passive and independently flying insects that works for all analysed frequency bands. At the lower frequency (the C band) insect scattering has been separated from Bragg scattering using a combination of the radar reflectivity factor and linear depolarization ratio. Retrieved values of the BLH from all radars are in a good agreement when compared to the BLH obtained with the co-located HALO Doppler lidar and ERA5 reanalysis data set. Our method showed some underestimation of the BLH after nighttime heavy precipitation yet demonstrated a potential to serve as a reliable method to obtain a BLH during clear-sky days. Additionally, the entrainment zone was observed by the C-band radar above the CBL in the form of a Bragg scatter layer. Aircraft observations of vertical profiles of potential temperature and water vapour concentration, collected in the vicinity of the radar, demonstrated some agreement with the Bragg scatter layer.</p>A. FranckD. MoisseevD. MoisseevV. VakkariV. VakkariM. LeskinenJ. LampilahtiV.-M. KerminenE. O'ConnorCopernicus PublicationsarticleEnvironmental engineeringTA170-171Earthwork. FoundationsTA715-787ENAtmospheric Measurement Techniques, Vol 14, Pp 7341-7353 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	Environmental engineering TA170-171 Earthwork. Foundations TA715-787
spellingShingle	Environmental engineering TA170-171 Earthwork. Foundations TA715-787 A. Franck D. Moisseev D. Moisseev V. Vakkari V. Vakkari M. Leskinen J. Lampilahti V.-M. Kerminen E. O'Connor Evaluation of convective boundary layer height estimates using radars operating at different frequency bands
description	<p>Knowledge of the atmospheric boundary layer state and evolution is important for understanding air pollution and low-level cloud development, among other things. There are a number of instruments and methods that are currently used to estimate boundary layer height (BLH). However, no single instrument is capable of providing BLH measurements in all weather conditions. We proposed a method to derive a daytime convective BLH using clear air echoes in radar observations and investigated the consistency of these retrievals between different radar frequencies. We utilized data from three vertically pointing radars that are available at the SMEAR II station in Finland, i.e. the C band (5 GHz), Ka band (35 GHz) and W band (94 GHz). The Ka- or W-band cloud radars are an integral part of cloud profiling stations of pan-European Aerosol, Clouds and Trace Gases Research Infrastructure (ACTRIS). Our method will be utilized at ACTRIS stations to serve as an additional estimate of the BLH during summer months. During this period, insects and Bragg scatter are often responsible for clear air echoes recorded by weather and cloud radars. To retrieve a BLH, we suggested a mechanism to separate passive and independently flying insects that works for all analysed frequency bands. At the lower frequency (the C band) insect scattering has been separated from Bragg scattering using a combination of the radar reflectivity factor and linear depolarization ratio. Retrieved values of the BLH from all radars are in a good agreement when compared to the BLH obtained with the co-located HALO Doppler lidar and ERA5 reanalysis data set. Our method showed some underestimation of the BLH after nighttime heavy precipitation yet demonstrated a potential to serve as a reliable method to obtain a BLH during clear-sky days. Additionally, the entrainment zone was observed by the C-band radar above the CBL in the form of a Bragg scatter layer. Aircraft observations of vertical profiles of potential temperature and water vapour concentration, collected in the vicinity of the radar, demonstrated some agreement with the Bragg scatter layer.</p>
format	article
author	A. Franck D. Moisseev D. Moisseev V. Vakkari V. Vakkari M. Leskinen J. Lampilahti V.-M. Kerminen E. O'Connor
author_facet	A. Franck D. Moisseev D. Moisseev V. Vakkari V. Vakkari M. Leskinen J. Lampilahti V.-M. Kerminen E. O'Connor
author_sort	A. Franck
title	Evaluation of convective boundary layer height estimates using radars operating at different frequency bands
title_short	Evaluation of convective boundary layer height estimates using radars operating at different frequency bands
title_full	Evaluation of convective boundary layer height estimates using radars operating at different frequency bands
title_fullStr	Evaluation of convective boundary layer height estimates using radars operating at different frequency bands
title_full_unstemmed	Evaluation of convective boundary layer height estimates using radars operating at different frequency bands
title_sort	evaluation of convective boundary layer height estimates using radars operating at different frequency bands
publisher	Copernicus Publications
publishDate	2021
url	https://doaj.org/article/dcacaef7b2034882b3e246dcb6cba6e5
work_keys_str_mv	AT afranck evaluationofconvectiveboundarylayerheightestimatesusingradarsoperatingatdifferentfrequencybands AT dmoisseev evaluationofconvectiveboundarylayerheightestimatesusingradarsoperatingatdifferentfrequencybands AT dmoisseev evaluationofconvectiveboundarylayerheightestimatesusingradarsoperatingatdifferentfrequencybands AT vvakkari evaluationofconvectiveboundarylayerheightestimatesusingradarsoperatingatdifferentfrequencybands AT vvakkari evaluationofconvectiveboundarylayerheightestimatesusingradarsoperatingatdifferentfrequencybands AT mleskinen evaluationofconvectiveboundarylayerheightestimatesusingradarsoperatingatdifferentfrequencybands AT jlampilahti evaluationofconvectiveboundarylayerheightestimatesusingradarsoperatingatdifferentfrequencybands AT vmkerminen evaluationofconvectiveboundarylayerheightestimatesusingradarsoperatingatdifferentfrequencybands AT eoconnor evaluationofconvectiveboundarylayerheightestimatesusingradarsoperatingatdifferentfrequencybands
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Evaluation of convective boundary layer height estimates using radars operating at different frequency bands

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