06 Dec 2022
 | 06 Dec 2022

Multiscale meteorological controls and impact of soil moisture heterogeneity on radiation fog in complex terrain

Dongqi Lin, Marwan Katurji, Laura E. Revell, Basit Khan, and Andrew Sturman

Abstract. Coupled surface-atmosphere high-resolution simulations were carried out to understand radiation fog development and persistence in a city surrounded by complex terrain. The controls of mesoscale meteorology and microscale soil moisture heterogeneity on fog were investigated using case studies for the city of Christchurch, New Zealand. Numerical model simulations from the synoptic to micro- scale were carried out using the Weather Research and Forecasting (WRF) model and the Parallelised Large-Eddy Simulation Model (PALM). Heterogeneous soil moisture, land use, and topography were included. The spatial heterogeneity of soil moisture was derived using Landsat 8 (, last access: 10 October 2022) satellite imagery and ground-based meteorological observations. Eight simulations were carried out under identical meteorological conditions. One contained homogeneous soil moisture and one contained heterogeneous soil moisture derived from Landsat 8 imagery. For the other six simulations, the soil moisture heterogeneity magnitudes were amplified following the observed spatial distribution to aid our understanding of the impact of soil moisture heterogeneity. Our results showed that soil moisture heterogeneity did not significantly change the general spatial structure of near-surface fog occurrence, even when amplified. However, compared to homogeneous soil moisture, spatial heterogeneity in soil moisture leads to significant changes in radiation fog duration. The resulting changes in fog duration can be more than 50 minutes, although such changes are not directly correlated with spatial variations in soil moisture. The simulations showed that the mesoscale (104 to 2 × 105 m) meteorology controls the location of fog occurrence, while soil moisture heterogeneity alters fog duration at the microscale (10−2 to 103 m). Our results highlight the importance of including soil moisture heterogeneity for accurate spatiotemporal fog forecasting.

Dongqi Lin et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2022-1229', Stephanie Westerhuis, 10 Jan 2023
  • RC2: 'Comment on egusphere-2022-1229', Anonymous Referee #2, 01 Feb 2023
  • EC1: 'Comment from co-editor on egusphere-2022-1229', Heini Wernli, 03 Feb 2023
  • AC1: 'Authors' response to reviewers on egusphere-2022-1229', Dongqi Lin, 24 Mar 2023

Dongqi Lin et al.


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Short summary
Accurate fog forecast is difficult in a complex environment. Spatial variations in soil moisture could have impact on fog. Here we carried out fog simulations with spatially different soil moisture in complex topography. The soil moisture was calculated using satellite observations. The results show that the spatial variations in soil moisture do not have significant impact on where fog occurred, but do impact how long fog lasted. This finding could improve fog forecast in the future.