Fog Research: A Review of Past Achievements and Future Perspectives

The scientific community that includes meteorologists, physical scientists, engineers, medical doctors, biologists, and environmentalists has shown interest in a better understanding of fog for years because of its effects on, directly or indirectly, the daily life of human beings. The total economic losses associated with the impact of the presence of fog on aviation, marine and land transportation can be comparable to those of tornadoes or, in some cases, winter storms and hurricanes. The number of articles including the word ``fog' in Journals of American Meteorological Society alone was found to be about 4700, indicating that there is substantial interest in this subject. In spite of this extensive body of work, our ability to accurately forecast/nowcast fog remains limited due to our incomplete understanding of the fog processes over various time and space scales. Fog processes involve droplet microphysics, aerosol chemistry, radiation, turbulence, large/small-scale dynamics, and surface conditions (e.g., partaining to the presence of ice, snow, liquid, plants, and various types of soil). This review paper summarizes past achievements related to the understanding of fog formation, development and decay, and in this respect, the analysis of observations and the development of forecasting models and remote sensing methods are discussed in detail. Finally, future perspectives for fog-related research are highlighted.     

Statistical considerations for grain-size analyses of tills

Relative percentages of sand, silt, and clay from samples of the same till unit are not identical because of different lithologies in the source areas, sorting in transport, random variation, and experimental error. Random variation and experimental error can be isolated from the other two as follows. For each particle-size class of each till unit, a standard population is determined by using a normally distributed, representative group of data. New measurements are compared with the standard population and, if they compare satisfactorily, the experimental error is not significant and random variation is within the expected range for the population. The outcome of the comparison depends on numerical criteria derived from a graphical method rather than on a more commonly used one-way analysis of variance with two treatments. If the number of samples and the standard deviation of the standard population are substituted in at-test equation, a family of hyperbolas is generated, each of which corresponds to a specific number of subsamples taken from each new sample. The axes of the graphs of the hyperbolas are the standard deviation of new measurements (horizontal axis) and the difference between the means of the new measurements and the standard population (vertical axis). The area between the two branches of each hyperbola corresponds to a satisfactory comparison between the new measurements and the standard population. Measurements from a new sample can be tested by plotting their standard deviation vs. difference in means on axes containing a hyperbola corresponding to the specific number of subsamples used. If the point lies between the branches of the hyperbola, the measurements are considered reliable. But if the point lies outside this region, the measurements are repeated. Because the critical segment of the hyperbola is approximately a straight line parallel to the horizontal axis, the test is simplified to a comparison between the means of the standard population and the means of the subsample. The minimum number of subsamples required to prove significant variation between samples caused by different lithologies in the source areas and sorting in transport can be determined directly from the graphical method. The minimum number of subsamples required is the maximum number to be run for economy of effort.     

Seasonal and interannual variability of carbon dioxide and water balances of a grassland

There is great international concern over the increase of atmospheric carbon dioxide and its effect on vegetation and climate, and vice versa. Many studies on this issue are based on climate model calculations or indirect satellite observations. In contrast we present a 12-year study (1994–2005) on the net ecosystem exchange of carbon dioxide (NEE) and precipitation surplus (i.e., precipitation–evaporation) of a grassland area in the centre of the Netherlands. On basis of direct flux observations and a process-based model we study and quantify the carbon uptake via assimilation and carbon release via soil and plant respiration. It appears that nearly year-round the assimilation term dominates, which indicates an accumulation of carbon dioxide. The mean net carbon uptake for the 12-year period is about 3 tonnes C per hectare, but with a strong seasonal and interannual variability depending on the weather and water budget. This variability may severely hamper the accurate quantification of carbon storage by vegetation in our present climates and its projection for future climates.     

What conditions supply chain strategies of ports? The case of Dubai

Recent academic debates about port competition have centered on the strategic responses of port authorities, operators, managers and owners to the emergence of global supply chains. The competitive performance of a port authority or operator, given the rise of the integrated logistics sector, depends increasingly on its strategic relationship to these supply chains and rather less on traditional port competition factors such as hinterland size and physical infrastructure. However, there are few empirical studies investigating the degree to which particular port actors are capable of inserting themselves into global supply chains. In this article we ask what factors condition the supply chain strategies of port actors. We hypothesize that the strategic supply chain choices of a port authority or operator are conditioned by the territorialized institutional framework in which the dominant actors in a port operate. We apply these insights through a case study of the transformation of Dubai Port Authority, and the rise of Dubai Ports World (DPW).

Soil stabilization with microbially induced desaturation and precipitation (MIDP) by denitrification: a field study

Acta Geotechnica - A field trial was performed to test the feasibility of microbially induced desaturation and precipitation (MIDP) by denitrification for the stabilization of a silty soil....     

Amplification and deformation of tidal wave in the Upper Scheldt Estuary

Ocean Dynamics - The records of HW and LW in the most upper part of the Scheldt Estuary since 1971 have been analysed together with the daily river discharge. The tidal range, the hydraulic head...     

‘Locationally disadvantaged’: planning governmentalities and peri-urban agricultural futures

ABSTRACT

Peri-urban areas are the interface between urban and rural regions, with these regions traditionally acting as foodbowls for adjacent urban areas. This peri-urban agriculture provides a diverse suite of benefits to urban areas. Increasingly, however, peri-urban areas are being converted to residential uses, driven in part by higher land values secured for land converted for residential development. In Sydney, planning and development has tended to treat peri-urban areas as ‘suburbs in waiting’. Using a Foucauldian governmentality approach, this paper investigates the prevailing rationalities in metropolitan-level strategic planning documents—in particular A Plan for Growing Sydney and the Draft South West District Plan—and how these rationalities relate to peri-urban agriculture. Our analysis shows that the three overarching rationalities—the global city, the compact city and the sustainability agenda—frame the urbanisation of peri-urban agricultural lands as necessary and inevitable, and only integrate agriculture as part of the future of the city of Sydney when it can be rationalised within the ‘global city’ narrative. As a result, peri-urban areas are not considered to have unique planning needs, but are imagined as latent spaces that will enable Sydney to meet its housing and job targets through their future development.     

Consistent past half-century trends in the atmosphere, the sea ice and the ocean at high southern latitudes

Simulations performed with the climate model LOVECLIM, aided with a simple data assimilation technique that forces a close matching of simulated and observed surface temperature variations, are able to reasonably reproduce the observed changes in the lower atmosphere, sea ice and ocean during the second half of the twentieth century. Although the simulated ice area slightly increases over the period 1980–2000, in agreement with observations, it decreases by 0.5 × 10⁶ km² between early 1960s and early 1980s. No direct and reliable sea ice observations are available to firmly confirm this simulated decrease, but it is consistent with the data used to constrain model evolution as well as with additional independent data in both the atmosphere and the ocean. The simulated reduction of the ice area between the early 1960s and early 1980s is similar to the one simulated over that period as a response to the increase in greenhouse gas concentrations in the atmosphere while the increase in ice area over the last decades of the twentieth century is likely due to changes in atmospheric circulation. However, the exact contribution of external forcing and internal variability in the recent changes cannot be precisely estimated from our results. Our simulations also reproduce the observed oceanic subsurface warming north of the continental shelf of the Ross Sea and the salinity decrease on the Ross Sea continental shelf. Parts of those changes are likely related to the response of the system to the external forcing. Modifications in the wind pattern, influencing the ice production/melting rates, also play a role in the simulated surface salinity decrease.     

3D quantification of mineral components and porosity distribution in Westphalian C sandstone by microfocus X-ray computed tomography

Microfocus X-ray computed tomography (µCT) measurements were performed on deltaic sandstone samples from the diagenetically altered Westphalian C strata (Campine basin, north-east Belgium) in order to collect three dimensional data on mineral (quartz, kaolinite, ankerite, etc.) and porosity distribution. The acquired µCT data were compared with point counting results of stained impregnated thin-sections to qualify the sensitivity of µCT. Comparison between techniques shows positive results with regard to the quantification of main mineral phases such as quartz and ankerite, and porosity distribution. However, major discrepancies exist when studying the clay minerals. This can be explained by the influence of microporosity associated with these clay minerals, resulting in partial volume effects.