Radiation and cloud-base lowering fog events

Observational analysis and evaluation of WRF and HARMONIE

Carlos Román-Cascón*, Carlos Yagüe, Gert-Jan Steeneveld, Gema Morales, J.A. Arrillaga, Mariano Sastre, Gregorio Maqueda

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

Most of the effects caused by fog are negative for humans. Yet, numerical weather prediction (NWP) models still have problems to simulate fog properly, especially in operational forecasts. In the case of radiation fog, this is partially caused by the large sensitivity to many aspects, such as the synoptic and local conditions, the near-surface turbulence, the aerosol and droplet microphysics, or the surface characteristics, among others. This work focuses on an interesting 8-day period with several alternating radiation and cloud-base lowering (CBL) fog events observed at the Research Centre for the Lower Atmosphere (CIBA) in the Spanish Northern Plateau. On the one hand, radiation fog events are associated with strong surface cooling leading to high stability close to the surface and low values of turbulence, giving rise to shallow fog. The evolution of this type of fog is markedly sensitive to the dynamical conditions close to the surface (i.e., wind speed and turbulence). On the other hand, CBL fog presents deeper thickness associated with higher values of turbulence and less stability. Subsequently, we evaluated the fog-forecasting skill of two mesoscale models (WRF and HARMONIE) configured as similar as possible. Both models present more difficulties simulating radiation fog events than CBL ones. However, the duration and vertical extension of the CBL fog events is normally overestimated. This extended-fog avoids the surface radiative cooling needed to simulate radiation fog events formed the following nights. Therefore, these periods with alternating CBL and radiation fog are especially challenging for NWP models.

Original languageEnglish
Pages (from-to)190-207
JournalAtmospheric Research
Volume229
DOIs
Publication statusPublished - 15 Nov 2019

Fingerprint

fog
turbulence
analysis
evaluation
radiation
cooling
weather
prediction
surface wind
droplet
wind velocity

Keywords

  • Cloud-base-lowering
  • Fog
  • HARMONIE
  • Model skill
  • Radiation
  • WRF

Cite this

Román-Cascón, Carlos ; Yagüe, Carlos ; Steeneveld, Gert-Jan ; Morales, Gema ; Arrillaga, J.A. ; Sastre, Mariano ; Maqueda, Gregorio. / Radiation and cloud-base lowering fog events : Observational analysis and evaluation of WRF and HARMONIE. In: Atmospheric Research. 2019 ; Vol. 229. pp. 190-207.
@article{564369aab0df49e7a50f8d5e02ecef36,
title = "Radiation and cloud-base lowering fog events: Observational analysis and evaluation of WRF and HARMONIE",
abstract = "Most of the effects caused by fog are negative for humans. Yet, numerical weather prediction (NWP) models still have problems to simulate fog properly, especially in operational forecasts. In the case of radiation fog, this is partially caused by the large sensitivity to many aspects, such as the synoptic and local conditions, the near-surface turbulence, the aerosol and droplet microphysics, or the surface characteristics, among others. This work focuses on an interesting 8-day period with several alternating radiation and cloud-base lowering (CBL) fog events observed at the Research Centre for the Lower Atmosphere (CIBA) in the Spanish Northern Plateau. On the one hand, radiation fog events are associated with strong surface cooling leading to high stability close to the surface and low values of turbulence, giving rise to shallow fog. The evolution of this type of fog is markedly sensitive to the dynamical conditions close to the surface (i.e., wind speed and turbulence). On the other hand, CBL fog presents deeper thickness associated with higher values of turbulence and less stability. Subsequently, we evaluated the fog-forecasting skill of two mesoscale models (WRF and HARMONIE) configured as similar as possible. Both models present more difficulties simulating radiation fog events than CBL ones. However, the duration and vertical extension of the CBL fog events is normally overestimated. This extended-fog avoids the surface radiative cooling needed to simulate radiation fog events formed the following nights. Therefore, these periods with alternating CBL and radiation fog are especially challenging for NWP models.",
keywords = "Cloud-base-lowering, Fog, HARMONIE, Model skill, Radiation, WRF",
author = "Carlos Rom{\'a}n-Casc{\'o}n and Carlos Yag{\"u}e and Gert-Jan Steeneveld and Gema Morales and J.A. Arrillaga and Mariano Sastre and Gregorio Maqueda",
year = "2019",
month = "11",
day = "15",
doi = "10.1016/j.atmosres.2019.06.018",
language = "English",
volume = "229",
pages = "190--207",
journal = "Atmospheric Research",
issn = "0169-8095",
publisher = "Elsevier",

}

Radiation and cloud-base lowering fog events : Observational analysis and evaluation of WRF and HARMONIE. / Román-Cascón, Carlos; Yagüe, Carlos; Steeneveld, Gert-Jan; Morales, Gema; Arrillaga, J.A.; Sastre, Mariano; Maqueda, Gregorio.

In: Atmospheric Research, Vol. 229, 15.11.2019, p. 190-207.

Research output: Contribution to journalArticleAcademicpeer-review

TY - JOUR

T1 - Radiation and cloud-base lowering fog events

T2 - Observational analysis and evaluation of WRF and HARMONIE

AU - Román-Cascón, Carlos

AU - Yagüe, Carlos

AU - Steeneveld, Gert-Jan

AU - Morales, Gema

AU - Arrillaga, J.A.

AU - Sastre, Mariano

AU - Maqueda, Gregorio

PY - 2019/11/15

Y1 - 2019/11/15

N2 - Most of the effects caused by fog are negative for humans. Yet, numerical weather prediction (NWP) models still have problems to simulate fog properly, especially in operational forecasts. In the case of radiation fog, this is partially caused by the large sensitivity to many aspects, such as the synoptic and local conditions, the near-surface turbulence, the aerosol and droplet microphysics, or the surface characteristics, among others. This work focuses on an interesting 8-day period with several alternating radiation and cloud-base lowering (CBL) fog events observed at the Research Centre for the Lower Atmosphere (CIBA) in the Spanish Northern Plateau. On the one hand, radiation fog events are associated with strong surface cooling leading to high stability close to the surface and low values of turbulence, giving rise to shallow fog. The evolution of this type of fog is markedly sensitive to the dynamical conditions close to the surface (i.e., wind speed and turbulence). On the other hand, CBL fog presents deeper thickness associated with higher values of turbulence and less stability. Subsequently, we evaluated the fog-forecasting skill of two mesoscale models (WRF and HARMONIE) configured as similar as possible. Both models present more difficulties simulating radiation fog events than CBL ones. However, the duration and vertical extension of the CBL fog events is normally overestimated. This extended-fog avoids the surface radiative cooling needed to simulate radiation fog events formed the following nights. Therefore, these periods with alternating CBL and radiation fog are especially challenging for NWP models.

AB - Most of the effects caused by fog are negative for humans. Yet, numerical weather prediction (NWP) models still have problems to simulate fog properly, especially in operational forecasts. In the case of radiation fog, this is partially caused by the large sensitivity to many aspects, such as the synoptic and local conditions, the near-surface turbulence, the aerosol and droplet microphysics, or the surface characteristics, among others. This work focuses on an interesting 8-day period with several alternating radiation and cloud-base lowering (CBL) fog events observed at the Research Centre for the Lower Atmosphere (CIBA) in the Spanish Northern Plateau. On the one hand, radiation fog events are associated with strong surface cooling leading to high stability close to the surface and low values of turbulence, giving rise to shallow fog. The evolution of this type of fog is markedly sensitive to the dynamical conditions close to the surface (i.e., wind speed and turbulence). On the other hand, CBL fog presents deeper thickness associated with higher values of turbulence and less stability. Subsequently, we evaluated the fog-forecasting skill of two mesoscale models (WRF and HARMONIE) configured as similar as possible. Both models present more difficulties simulating radiation fog events than CBL ones. However, the duration and vertical extension of the CBL fog events is normally overestimated. This extended-fog avoids the surface radiative cooling needed to simulate radiation fog events formed the following nights. Therefore, these periods with alternating CBL and radiation fog are especially challenging for NWP models.

KW - Cloud-base-lowering

KW - Fog

KW - HARMONIE

KW - Model skill

KW - Radiation

KW - WRF

U2 - 10.1016/j.atmosres.2019.06.018

DO - 10.1016/j.atmosres.2019.06.018

M3 - Article

VL - 229

SP - 190

EP - 207

JO - Atmospheric Research

JF - Atmospheric Research

SN - 0169-8095

ER -