Height-resolved Scaling Properties of Tropospheric Water Vapour based on Airborne Lidar Observations

Two-dimensional vertical water vapour cross sections of the free troposphere between altitudes of 2 and 10 km, measured by nadir-viewing airborne differential-absorption lidar with high spatial resolution, were analyzed using structure functions up to the fifth order. We found scale invariance, i.e. a power-law dependency of structure function on length scale, for scales between 5 and 100 km, for the horizontal time series of water vapour mixing ratio. In contrast to one-dimensional in situ measurements, the two-dimensional water vapor lidar observations allow height-resolved analyses of power-law scaling exponents at a vertical resolution of 200 m. The data reveal significantly different scaling properties above and below an air-mass boundary. They stem from three very dissimilar aircraft campaigns: COPS/ETReC over middle and southern Europe in summer 2007, T-PARC around Japan mostly over sea in late summer 2008, and T-IPY around Spitsbergen over sea in winter 2008. After discarding flight segments with low lidar signals or large data gaps, and after averaging horizontally to a resolution of between 1 and 5 km to obtain a high signal to noise ratio, structure functions were computed for 20 flights at various heights, adding up to a length of more than 300,000 km. The power-law scaling exponents of the structure functions do not show significant latitudinal, seasonal or land/sea dependency, but they do differ between air masses influenced by moist convection and air masses aloft, not influenced. A classification of the horizontal water vapour time series into two groups according to whether the series occurred above or below the level of nearby convective cloud tops could be performed by detecting the cloud top height from the lidar backscatter signal in the corresponding flight segment. We found that the scaling exponents can be divided into two groups depending on the respective air mass: The smoothness of the time series, expressed by the first-order scaling exponent, varies from less than 0.5 in the low-level convectively influenced air masses to values greater than 0.5 and most frequently near 0.6 in the higher-level air above the convective cloud tops. The time series’ intermittency, expressed by the variation of the scaling exponent with increasing order, is larger in convectively influenced air masses. These differences in variability strongly suggest that convection provides a source of moisture variability on small scales. Our results show that the high horizontal and vertical resolution of lidar observations allows a characterisation of the scale dependency of the water vapour field at scales close to and smaller than the smallest resolved scales in modern weather and climate models. This provides both a reference for validation of high resolution models and a basis for the design of stochastic or pdf-based parameterisations of clouds and convection

A Method for Modeling Low-Probability, High- Consequence Risk Events: Vessel Traffic on the Lower Mississippi River

[Excerpt] A variety of commodities, from chlorine to corn and petroleum to passengers, are transported on the lower Mississippi River regularly. Corn, wheat and coal are the most commonly carried commodities. From a human health and safety perspective, these are relatively benign products in that a vessel accident and spill of these are not directly hazardous to people, whatever other ecological disturbances may ensue. However, over eighty million tons of petroleum products are transported on the river annually. Over a million tons of liquid natural gas traverse the river through the center of New Orleans. Additionally, over 400,000 tons of ammonium nitrate2 pass through the center of Baton Rouge annually. The potential for a technological disaster is certainly present […] The vast majority of the literature relevant to the question of vessel accident risk concerns the question of on-board causes of vessel accidents. It is assumed that the predictors of which vessel will have an accident are on-board the vessel (i.e., vessel and crew characteristics). The most commonly cited on-board hazards include: the size of the vessel; the age of the vessel; the length of the vessel; whether the vessel is single or double hulled; the maintenance of the vessel; the classification society under which the vessel is registered; the type of ownership; the history of ownership; where the vessel is flagged (i.e., flag of convenience or traditional maritime nation); license qualifications of mates and engineers; the vessel’s casualty history; the vessel’s history of violations; whether the vessel has system (e.g., steering) redundancy; and personnel history (including manning levels and the comparison of the present levels of manning with that of the vessel in the past and with similar type vessels)

Voting at 16 – lessons for the future from the Scottish Referendum

The 2014 Referendum on Scottish independence raised many issues about the future of Scotland. It also produced an innovation as regards the electoral process by making 16 years the minimum age of participation. This article examines issues surrounding the voting age and draws on a schools-based study, which shed light on teacher and pupil opinion about this lower than usual threshold for voting. It is also concerned with how schools cover the teaching of politics and prepared students for the Referendum debate within a context of expected neutrality on a highly divisive matter. Some implications of extending the lower voting age for future elections are discussed

Promoting a career in engineering : an investigation of factors influencing career decision-making in New Zealand

This thesis reports on survey research, conducted on a sample of Year 12 students within New Zealand who attended school in the Greater Auckland region during Autumn 2009. The survey gathered data in order to assess the students’ knowledge, attitudes, and the perceived influences on those attitudes, towards engineering as a career or field of study. The purpose of the research was to better understand factors that may influence Year 12 New Zealanders’ career decisions, especially with respect to careers in engineering, with a view to recommending to stakeholders how enrolment into Bachelor of Engineering programs might be increased.Schools were selected using stratified random sampling, and their Principals were approached through a strategy of emails, telephone calls, and by local personal contact. The students were surveyed via an online questionnaire, administered by school teachers and/or careers personnel, and conducted within school hours. A total of 292 students from 9 schools within the Greater Auckland region took part, and a variety of statistical techniques was used to analyze their responses.The New Zealand students were assessed as having a good knowledge of the benefits and demands of a career in engineering, and a positive attitude towards many of the suggested traits of engineering careers. Contradictions were found between the students’ perceived influences on their career choices, and the patterns of their response choices to a number of the survey questions. Statistically significant relationships were also found between the gender and ethnic background of the survey sample, the students’ attitudes towards careers in general and towards careers specifically in engineering, the influences on those attitudes, and the students’ selection of engineering as a career or field of study.Conclusions were drawn based on the research findings, and recommendations made as to how enrolment into Bachelor of Engineering programs might be increased. The recommendations formulated are directed to practitioners within the engineering profession and also to advisors within the education sector. Recommendations for additional research are then made