Fog from the Ground Up: Investigating the Conditions Under Which Fog Forms and Evolves Within the Nocturnal Boundary Layer

Fog is of critical importance to forecast accurately, not least because of the hazard it presents to human safety. Yet, while weather forecasts have improved significantly over recent decades—and continue to improve—fog remains a particularly challenging phenomenon to predict. The research presented within this thesis takes a step back from...

Why does fog deepen?: An analytical perspective

The overall depth of a fog layer is one of the important factors in determining the hazard that a fog event presents. With discrete observations and often coarse numerical grids, however, fog depth cannot always be accurately determined. To address this, we derive a simple analytical relation that describes the change in depth of a fog...

Revisiting wind speed measurements using actively heated fiber optics: A wind tunnel study

Near-surface wind speed is typically only measured by point observations. The actively heated fiber-optic (AHFO) technique, however, has the potential to provide high-resolution distributed observations of wind speeds, allowing for better spatial characterization of fine-scale processes. Before AHFO can be widely used, its performance needs...

Fog Alleviation: An Unintended Benefit of Airport Construction and Operations at Amsterdam’s Schiphol Airport?

This poster will be presented at EMS 2019 in Copenhagen. Fog - in particular, the associated reduction is visibility - presents a hazard to airport operations. Although tech- nology has improved to allow greater safety during fog events, protocol still requires more time between aircraft movements, often resulting in significant delays and...

Missed Fog: Understanding the Growth of Fog from the Ground Up

Conventional in situ observations of visibility and other meteorological variables are restricted to a limited number of heights near the surface, with the lowest observation often made above 1 m. This can result in missed observations of shallow fog as well as the initial growth stage of thicker fog layers. At the same time, numerical...

Dutch fog: On the observed spatio-temporal variability of fog in the Netherlands

The Netherlands is characterized by highly variable land use within a small area, and a strong influence of the North Sea on national climate. Devoid of significant topography, it is an excellent location for assessing the relative influence of various factors on fog occurrence in the absence of terrain effects. Using observations from a...

Missed Fog?: On the Potential of Obtaining Observations at Increased Resolution During Shallow Fog Events

Conventional in situ observations of meteorological variables are restricted to a limited number of levels near the surface, with the lowest observation often made around 1-m height. This can result in missed observations of both shallow fog, and the initial growth stage of thicker fog layers. At the same time, numerical experiments have...

Understanding and Reducing False Alarms in Observational Fog Prediction

The reduction in visibility that accompanies fog events presents a hazard to human safety and navigation. However, accurate fog prediction remains elusive, with numerical methods often unable to capture the conditions of fog formation, and observational methods having high false-alarm rates in order to obtain high hit rates of prediction. In...

Estimating the Cross-Shelf Export of Riverine Materials: Part 1. General Relationships From an Idealized Numerical Model

Rivers deliver large amounts of terrestrially derived materials (such as nutrients, sediments, and pollutants) to the coastal ocean, but a global quantification of the fate of this delivery is lacking. Nutrients can accumulate on shelves, potentially driving high levels of primary production with negative consequences like hypoxia, or be...

Estimating the Cross-Shelf Export of Riverine Materials: Part 2. Estimates of Global Freshwater and Nutrient Export

Rivers deliver large amounts of fresh water, nutrients, and other terrestrially derived materials to the coastal ocean. Where inputs accumulate on the shelf, harmful effects such as hypoxia and eutrophication can result. In contrast, where export to the open ocean is efficient riverine inputs contribute to global biogeochemical budgets....