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Three-dimensional simulations of the ozone layer and atmospheric dynamics of earth-like habitable planets
Full text linkThis thesis investigates how the atmospheric circulation and ozone distribution of a planet with the size, the mass, the continental distribution and topography, the oceans, and the atmospheric composition and circulation of the present day Earth (Earth-like planet) is altered by local and global radiative forcing changes using three-dimensional simulations. These simulations are generated using the coupled 3D chemistry-climate model CESM1(WACCM), which incorporates the entire atmosphere up to an altitude of 140 km, as well as parametrizations for the full atmospheric chemistry, photochemistry, cloud microphysics and small-scale gravity wave flux. These features allow for a realistic simulation of the composition and dynamics of the Earth's atmosphere.
The investigation is composed of three studies. In the first study, the effects in the lower tropospheric dynamics generated by a local radiative forcing change on the present day Earth are investigated. The forcing change is implemented by changing the local soil colour and therefore the local albedo. In order to isolate the generated perturbation from the background waves, a small-scale perturbation analysis is performed for the first 5 days of the simulation. The soil colour change generates an upwards propagating convective perturbation, which induces a radially propagating circular wave at an altitude of 2 km. This wave has a mean wave velocity of (v) = 200 ± 50 m/s, a mean horizontal wavelength (λ) = 3000 ± 500 km and a mean wave period (p) = 4 ± 1 h. In addition to this wave, a secondary wave is also generated over the tropical Amazon convection zone when the primary wave collides with it. The secondary wave has a mean wave velocity (v) = 220± 40 m/s, a mean horizontal wavelength (λ) = 2600 ± 600 km and a mean wave period (p) = 3 ± 1 h.
The second study expands the scope of the first study by investigating how a global radiative forcing change affects the atmospheric circulation and ozone distribution of an Earth-like planet orbiting a Sun-like star. In this study, the forcing change is implemented by tidally locking the planet. The simulations reveal that, when the full photochemistry and atmospheric dynamics are included, the planet's middle atmosphere adjusts to the new conditions within a relatively short time (roughly 80 days from the start of the simulation) and its atmospheric circulation and ozone distribution are altered.
The Brewer-Dobson circulation is replaced by a day side upwelling and a night side downwelling. The total ozone content of the tidally locked planet is reduced by
19.3% compared to the Earth due to radiation and transport changes. Specifically, the total ozone content mean is reduced by 23.21% on the day side and by 15.52% on the night side. The middle stratospheric ozone accumulates on the day side of the planet resulting in a day-night variation of 40%. In comparison, the Earth's daynight variation is only 2%. The lower stratospheric ozone is mainly influenced by the altered circulation and is characterised by enhanced night side zone and depleted day side regions. The planet's mesospheric ozone is similar to the Earth's mesospheric ozone distribution, with decreased ozone on the day side and enhanced ozone on the night side. For a distant observer, the planet's total ozone content will vary up to 23% during its revolution around its parent star.
Finally, the third study is an extension of the second study. It investigates, in more detail, the 3D atmospheric circulation of a tidally locked planet. An intercomparison with the fast rotating Earth is performed and the effects of the sea surface temperature (SST) on the middle atmosphere of the tidally locked planet are simulated and analysed. For this study, two extreme SSTs are used: a present day Earth SST and a tidally locked aquaplanet SST. The simulation shows that the SST has a limited influence on the middle atmosphere. The warmer present day Earth SST generated, on average, a lower tropospheric heating of 3.7 K, an upper tropospheric cooling of 4 K, a lower stratospheric heating of 3.8 K, a lower mesospheric cooling of 1.13 K and an upper mesospheric heating of 4.3 K. The lower stratospheric heating is possibly generated by the increased infrared radiation flux from the warmer present day Earth SST surface, as the lower stratospheric ozone will absorb the increased infrared radiation at 9.6 μm. The SST change has no significant influence on the primary ozone layer, while the warmer SST leads to a strong increase of the secondary ozone layer. The tropospheric and stratospheric results are in agreement with past studies of the influence of SST variability on the Earth's troposphere and stratosphere. The lower mesospheric cooling is consistent with increased mesospheric wave-breaking due to the warmer present day Earth SST. Both simulations are characterised by an upwelling on the day side and downwelling on the night side, while the stratospheric and mesospheric circulation is only weakly influenced by the underlying SST. Generally, the reduced Coriolis force of the tidally locked planet leads to enhanced meridional mixing and consequently to a relatively isothermal temperature distribution of the middle atmosphere. The occurrence of large-scale vortices and variable jet streams depends, to some extent, on the SST distribution
A comprehensive review of residential electricity load profile models
Full text linkA third of the final electricity in the EU is consumed by households. The increased usage of multiple electrical devices, electromobility, self-generation and consumption of electricity as well as work-from-home will fundamentally change the residential electricity load profile, so a deep understanding of the current state of residential electricity load profile modelling is necessary. The objective of this paper is to perform a literature review, evaluate the current state of the residential electricity load profile modelling, categorise the models, propose future research directions and applications, identify the challenges the researchers face when building these models and offer possible solutions. Thirty two residential electricity load profile models are identified and a new definition of the residential electricity load profile model is proposed. A new categorisation system based on the identification of the main features of these thirty two studies is introduced. Future research directions and applications are presented and the most important challenges that modellers face when attempting to build such models are identified and discussed. The most important challenge identified is the privacy concerns of the participants or potential participants. These concerns are at least partially responsible for the existence of the rest of the challenges. The creation and implementation of an anonymisation algorithm, before any human has access to any measured datasets, the implementation of a crowd sourcing approach which addresses the privacy concerns of the citizens and increased funding for the installation of privacy-proof smart-meters by the public and measurement campaigns are identified as possible solutions to the challenges faced by modellers
Characterising the three-dimensional ozone distribution of a tidally locked Earth-like planet
Full text linkWe simulate the 3D ozone distribution of a tidally locked Earth-like exoplanet using the high-resolution, 3D chemistry climate model CESM1(WACCM) and study how the ozone layer of a tidally locked Earth (TLE) (ΩTLE = 1/365 days)
differs from that of our present-day Earth (PDE) (ΩPDE = 1/1 day). The middle atmosphere reaches a steady state a symptotically within the first 80 days of the simulation. An upwelling, centred on the subsolar point, is present on the
day side while a downwelling, centred on the antisolar point, is present on the night side. In the mesosphere, we find similar global ozone distributions for the TLE and the PDE, with decreased ozone on the day side and enhanced ozone on the night side. In the lower mesosphere, a jet stream transitions into a large-scale vortex around a low-pressure system, located at low latitudes of the TLE night side. In the middle stratosphere, the concentration of odd oxygen is approximately equal to that of the ozone [(Ox) ≈ (O3)]. At these altitudes, the lifetime of odd oxygen is ~16 h and the transport processes significantly contribute to the global distribution of stratospheric ozone. Compared to the PDE, where the strong Coriolis force acts as a mixing barrier between low and high latitudes, the transport processes of the
TLE are governed by jet streams variable in the zonal and meridional directions. In the middle stratosphere of the TLE, we find high ozone values on the day side, due to the increased production of atomic oxygen on the day side, where it immediately recombines with molecular oxygen to form ozone. In contrast, the ozone is depleted on the night side, due to changes in the solar radiation distribution and the presence of a downwelling. As a result of the reduced Coriolis force, the tropical and extratropical air masses are well mixed and the global temperature distribution of the TLE stratosphere has smaller horizontal gradients than the PDE. Compared to the PDE, the total ozone column global mean is reduced by ~19.3 %. The day side and the night side total ozone column means are reduced by 23.21 and 15.52 %,
respectively. Finally, we present the total ozone column (TOC) maps as viewed by a remote observer for four phases of the TLE during its revolution around the star. The mean TOC values of the four phases of the TLE vary by up to 23 %
A traveling atmospheric disturbance generated by a soil colour change in a high-resolution climate model experiment
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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