TY - JOUR

T1 - On the effect of nocturnal radiation fog on the development of the daytime convective boundary layer

T2 - A large-eddy simulation study

AU - Schwenkel, Johannes

AU - Maronga, Björn

N1 - Funding information: information German Research Foundation, Grant/Award Number: MA 6383/1-2All simulations were carried out on the computer clusters of the North-German Supercomputing Alliance (HLRN). Python 3.8 was used for data analysis and visualization. The PALM code can be accessed at https://gitlab.palm-model.org/. We sincerely thank Marie Mazoyer and Christine Lac for reviewing this article. Their numerous valuable comments helped to improve the manuscript. Open Access funding enabled and organized by Projekt DEAL. [Correction added on 28 September 2022, after first online publication: The Acknowledgements section has been amended in this updated version of the article.]

PY - 2022/11/12

Y1 - 2022/11/12

N2 - The potential effect of failing to predict nocturnal deep radiation fog on the development of the daytime convective boundary layer (CBL) is studied using large-eddy simulations. Typical spring and autumn conditions for the mid-latitudes are used to perform simulations in pairs. Fog formation is allowed in one simulation of each pair (nocturnal fog [NF]) and is suppressed in the other (clear sky [CS]). This allows for the identification of properties (temperature, humidity, boundary-layer depth), conditions, and processes in CBL development that are affected by fog. Mixing-layer temperatures and boundary-layer depths immediately after fog dissipation in CSs are shown to be up to 2.5 K warmer and 200 m higher, respectively, than the NF counterparts. Additionally, greater water vapor mixing ratios are found in the CSs. However, owing to greater temperatures, relative humidities at the CBL top are found to be less in CSs than in the corresponding NFs. This relative humidity difference might be an indication that cloud formation is suppressed to some extent. The magnitude of the differences between CSs and NFs during the day is mainly correlated to the fog depth (in terms of duration and liquid water path), whereas the key processes responsible for differences are the atmospheric long-wave cooling of the fog layer (for temperature development) and droplet deposition (for water vapor mixing ratio development).

AB - The potential effect of failing to predict nocturnal deep radiation fog on the development of the daytime convective boundary layer (CBL) is studied using large-eddy simulations. Typical spring and autumn conditions for the mid-latitudes are used to perform simulations in pairs. Fog formation is allowed in one simulation of each pair (nocturnal fog [NF]) and is suppressed in the other (clear sky [CS]). This allows for the identification of properties (temperature, humidity, boundary-layer depth), conditions, and processes in CBL development that are affected by fog. Mixing-layer temperatures and boundary-layer depths immediately after fog dissipation in CSs are shown to be up to 2.5 K warmer and 200 m higher, respectively, than the NF counterparts. Additionally, greater water vapor mixing ratios are found in the CSs. However, owing to greater temperatures, relative humidities at the CBL top are found to be less in CSs than in the corresponding NFs. This relative humidity difference might be an indication that cloud formation is suppressed to some extent. The magnitude of the differences between CSs and NFs during the day is mainly correlated to the fog depth (in terms of duration and liquid water path), whereas the key processes responsible for differences are the atmospheric long-wave cooling of the fog layer (for temperature development) and droplet deposition (for water vapor mixing ratio development).

KW - boundary-layer development

KW - diurnal cycle

KW - large-eddy simulation

KW - misrepresenting fog

KW - PALM

KW - radiation fog

KW - turbulence

UR - http://www.scopus.com/inward/record.url?scp=85138331160&partnerID=8YFLogxK

U2 - 10.1002/qj.4352

DO - 10.1002/qj.4352

M3 - Article

AN - SCOPUS:85138331160

VL - 148

SP - 3166

EP - 3183

JO - Quarterly Journal of the Royal Meteorological Society

JF - Quarterly Journal of the Royal Meteorological Society

SN - 0035-9009

IS - 748

ER -