Modeling the exchange of water and energy over natural land surfaces = Het modelleren van de uitwisseling van water en energie over natuurlijke landschappen

This thesis deals with the modeling of the surface energy balance and the atmospheric boundary layer over natural land surfaces, on scales of the grid cell of large-scale atmospheric models. In the first part, a model to calculate the canopy conductance as a function of environmental variables evaluated at leaf level is developed and validated. The parameter values of this approach are retained from plant-physiological theory. For a C 4 prairie grass in Kansas and a C 3 soybean crop in southern France, the plant-physiological approach gives better estimates of the canopy conductance, compared to a traditional Jarvis-Stewart approach which relates the canopy conductance to environmental variables at a reference level, using empirical-statistical functions. For a C 3 grassland in the Netherlands, both the plant-physiological approach and the Jarvis-Stewart approach give comparable estimates of the latent heat flux density. In the second part, two approaches to calculate the impact of soil moisture stress on the surface flux densities over natural, heterogeneous areas are compared: a bulk approach where the soil moisture content is assumed to be uniform in a grid cell, and a distributed approach which takes account of the spatial variation of the soil moisture content. In wet conditions, the bulk approach gives larger predictions of the latent heat flux density than the distributed approach. In dry conditions the bulk approach gives lower predictions than the distributed approach. Especially for dry climates the bulk approach predicts during the dry season a severe suppression of the latent heat flux density. In the third part, using three cases that occur frequently in nature it is shown that only a tiling approach can provide estimates of the averaged surface flux densities that are consistent with the averaged temperature difference over the surface layer, the layer of air adjacent to the surface, in all situations

Modelsimulaties van het stadsklimaat van Rotterdam

Modelsimulaties zijn uitgevoerd ter inschatting van het Urban Heat Island effect van Rotterdam. Hiervoor is de meest recente versie van het Weather Research & Forecasting (WRF) model gebruikt dat is uitgerust met een Urban Canopy Model. Bovendien is gebruik gemaakt van specifieke stadeigenschappen die zeer recent beschikbaar zijn gekome

The impact of climate change on the critical weather conditions at Schiphol airport (Impact)

Schiphol is van groot belang voor de economische positie van Nederland. De luchthaven is erg gevoelig voor kritieke weersomstandigheden zoals mist, intensieve neerslag en hevige wind. Als gevolg van klimaatverandering verwachten we dat ook de variabiliteit van het weer op de luchthaven en de frequentie en intensiteit van kritieke weersomstandigheden zullen veranderen, maar een precieze kwantificering daarvan ontbreekt. De belangrijkste doelstelling van dit project is daarom het verstrekken en demonstreren van het volgende generatie weer‐ en klimaatmodel HARMONIE. Dit is een nieuw model dat beter geschikt lijkt om het effect van klimaatverandering op lokale kritieke weersomstandigheden op de luchthaven te kwantificeren en te begrijpen. Bovendien zal kennis uit dit project worden gebruikt om de kwaliteit van onze huidige en toekomstige weersvoorspellingen te verbeteren. In dit project wordt het potentieel van het HARMONIE model, om meer gedetailleerdere en nauwkeurigere weersvoorspellingen voor luchthaven Schiphol te leveren dan ons huidige operationele weermodel HIRLAM, nagegaan in het huidige klimaat

Professionalism, Golf Coaching and a Master of Science Degree: A commentary

As a point of reference I congratulate Simon Jenkins on tackling the issue of professionalism in coaching. As he points out coaching is not a profession, but this does not mean that coaching would not benefit from going through a professionalization process. As things stand I find that the stimulus article unpacks some critically important issues of professionalism, broadly within the context of golf coaching. However, I am not sure enough is made of understanding what professional (golf) coaching actually is nor how the development of a professional golf coach can be facilitated by a Master of Science Degree (M.Sc.). I will focus my commentary on these two issues

Representing the atmospheric boundary layer in climate models of intermediate compexity

In this study the role of atmospheric boundary layer schemes in climate models is investigated. Including a boundary layer scheme in an Earth system model of intermediate complexity (EMIC) produces only minor differences in the estimated global distribution of sensible and latent heat fluxes over land (upto about 15% of the net radiation at the surface). However, neglecting of boundary layer processes, such as the development of a well-mixed layer over land or the impact of stability on the exchange coefficient in the surface layer, leads to erroneous surface temperatures, especially in convective conditions with low wind speeds. As these conditions occur frequently, introducing a boundary layer scheme in an EMIC gives reductions in June-July-August averaged surface temperature of 1¿2 °C in wet areas, to 5¿7 °C in desert areas. Even a relatively simple boundary layer scheme provides reasonable estimates of the surface fluxes and surface temperatures. Detailed schemes that solve explicitly the turbulent fluxes within the boundary layer are only required when vertical profiles of potential temperature are needed