Diurnal Dust Devil Behaviour for the Viking 1 Landing Site: Sols 1 to 30

Previous martian studies have provided an understanding of diurnal dust devil behaviour for Viking 2 and the Mars Pathfinder landing sites. It is the purpose of this work to complete this analysis by analysing the meteorological data from the Viking 1 landing site

Viking Lander 1 and 2 revisited: The characterisation and detection of Martian dust devils

Dust devil data from Mars is limited by a lack of data relating to diurnal dust devil behaviour. The meteorological data from the Viking landers has been revisited to provide these diurnal statistics

The Housing Market(s) of San Diego

This paper uses an assignment model to understand the cross section of house prices within a metro area. Movers’ demand for housing is derived from a lifecycle problem with credit market frictions. Equilibrium house prices adjust to assign houses that differ by quality to movers who differ by age, income and wealth. To quantify the model, we measure distributions of house prices, house qualities and mover characteristics from micro data on San Diego County during the 2000s boom. The main result is that cheaper credit for poor households was a major driver of prices, especially at the low end of the market.

Shopping online and/or in-store? A structural equation model of the relationships between e-shopping and in-store shopping

Searching product information or buying goods online is becoming increasingly popular and could affect shopping trips. However, the relationship between e-shopping and in-store shopping is currently unclear. The aim of this study is to investigate empirically how the frequencies of online searching, online buying, and non-daily shopping trips relate to each other, after controlling for sociodemographic, land use, behavioral, and attitudinal characteristics. Data were collected from 826 respondents residing in four municipalities (one urban, three suburban) in the center of the Netherlands, using a shopping survey. Structural Equation Modeling was used to give insight in the mutual dependencies of the endogenous variables, and in direct and indirect effects between variables. The findings suggest that complementarity or generation between e-shopping and in-store shopping seems to be more likely to occur than substitution. The more often people search online, the more shopping trips they tend to make. Frequent in-store shoppers also buy frequently online. Shop accessibility has a negative effect on the frequency of online searching; the more shops are nearby, the less often persons search online. However, shop accessibility influences the frequency of online buying positively; the more shops are nearby, the more often persons buy online. Urbanisation level affects e-shopping indirectly via Internet use: urban residents shop online more often than suburban residents do, because urban residents use the Internet more often.

The impact of metropolitan structure on commute behavior in the Netherlands: a multilevel approach

The effect of decentralization of land uses on travel behavior remains an unresolved issue in the academic literature. Some US researchers argue that a tendency towards polycentrism is associated with decreasing commute times and distances. Others have, however, suggested and shown the opposite commute times and distances tend to be longer in polycentric than in monocentric urban areas. Using this controversy as a starting point, we analyse how monocentric and polycentric urban structures affect commuting in the Netherlands with data from the 1998 National Travel Survey. Four kinds of urban systems are distinguished: one monocentric and three polycentric systems. In contrast to most previous work, we use multilevel regression analysis to take adequate account of the effects of individual and household attributes. The results indicate that urban structure influences most dimensions of commuting considered here. Yet, individual and household level variables are more important determinants than characteristics of the residential and workplace environment. Gender, household type and their interaction effects remain important determinants of commute behavior in the Netherlands; particularly women in two-earner households commute less than average. Education and income are both positively related to the amount of commuting. Further, the effects of mono- and polycentrism on commuting are more complicated than the literature makes us believe. When individual and household level factors are taken account of, polycentrism does not always result in more efficient commute patterns than monocentric urban structures: in most polycentric urban areas commute distances and times are longer than in monocentric ones. Only when polycentric regions consist of several relatively independent and self-contained development nodes are commute distances shorter than elsewhere. Commute times are in that case comparable to those in monocentric urban areas. The impact of urban structure disappears when commute time is related to the time spent on work activities; the ratio between commute time and work duration is not much affected by the type of urban system in which workers reside. The fact that commute times and distances are not lower in polycentric urban areas may be attributed to the specific situation in the Netherlands: strong spatial planning policies may have obstructed the relocation of employment and housing in close proximity of each other. However, the longer commute in most policentric regions may also indicate that workers and their households not always behave as urban economic theory predicts. In any case, the results show that it is necessary to distinguish several types of polycentric systems instead of merely using a dichotomy of monocentric and polycentric in the analysis of commuting.

An acoustic view of ocean mixing

Knowledge of the parameter K (turbulent diffusivity/"mixing intensity") is a key to understand transport processes of matter and energy in the ocean. Especially the almost vertical component of K across the ocean stratification (diapycnal diffusivity) is vital for research on biogeochemical cycles or greenhouse gas budgets. Recent boost in precision of water velocity data that can be obtained from vessel-mounted acoustic instruments (vmADCP) allows identifying ocean regions of elevated diapycnal diffusivity during research cruises - in high horizontal resolution and without extra ship time needed. This contribution relates acoustic data from two cruises in the Tropical North East Atlantic Oxygen Minimum Zone to simultaneous field observations of diapycnal diffusivity: pointwise measurements by a microstructure profiler as well as one integrative value from a large scale Tracer Release Experiment