Johannes HorakCity of Linz · Planung Technik und Umwelt
Doctor of Philosophy
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Citations since 2017
9 Research Items
December 2015 - present
- PhD Student
- Work on simplified physics downscaling techniques.
September 2013 - August 2015
- Research Assistant
- Experimental and modelling work on the interaction of high power CW lasers with metal plates.
March 2012 - February 2013
- Master's Student
- Experimental work with high vacuum setups, molecular beam sources and pulsed lasers. The resulting thesis characterizes a self-designed molecular beam source based on the soft laser desorption mechanism LIAD.
A thorough and honest evaluation provides the foundation for all results obtained with a model. It is the key to increase trust in models, novel and established alike. Evaluation fosters model understanding and directly triggers improvements. Additionally, it allows to quantify the uncertainties of the results. However, there is no evaluation appro...
The evaluation of models in general is a nontrivial task and can, due to epistemological and practical reasons, never be considered complete. Due to this incompleteness, a model may yield correct results for the wrong reasons, i.e., via a different chain of processes than found in observations. While guidelines and strategies exist in the atmospher...
The availability of in situ atmospheric observations decreases with elevation and topographic complexity. Data sets based on numerical atmospheric modeling, such as reanalysis data sets, represent an alternative source of information, but they often suffer from inaccuracies, e.g., due to insufficient spatial resolution. sDoG (statistical Downscalin...
The verification of models in general is a non-trivial task and can, due to epistemological and practical reasons, never be considered as complete. As a consequence, a model may yield correct results for the wrong reasons, i.e. by a different chain of processes than found in observations. While in the atmospheric sciences guidelines and strategies...
The coarse grid spacing of global circulation models necessitates the application of downscaling techniques to investigate the local impact of a changing global climate. Difficulties arise for data-sparse regions in complex topography, as they are computationally demanding for dynamic downscaling and often not suitable for statistical downscaling d...
The coarse grid spacing of global circulation models necessitates the application of climate downscaling to investigate the local impact of a changing global climate. Difficulties arise for data sparse regions in complex topography which are computationally demanding for dynamic downscaling and often not suitable for statistical downscaling due to...
In vehicles that are parked, no ventilation and/or air conditioning takes place. If a vehicle is exposed to direct solar radiation, an immediate temperature rise occurs. The high cabin air temperature can threaten children and animals that are left unattended in vehicles. In the USA, lethal heat strokes cause a mean death rate of 37 children per ye...
Background The transport of veterinary drugs must comply with the general standards for drug storage. Although many vehicles are equipped with active heating and/or cooling devices assuring recommended storage conditions, simple insulated transport boxes are also often used. In this study, measurements for typical transport boxes were performed und...
In this work, the energy transfer from intense continuous-wave laser beams with a wavelength of 1070 nm, a power in the kilowatt range, and with diameters in the millimeter and centimeter range to metal samples is investigated. While the absorptivity of iron and steel samples is almost constant for laser intensities below 3.4 kW/cm², a decrease in...
Laser-induced acoustic desorption (LIAD) has recently been established as a tool for analytical chemistry. It is capable of launching intact, neutral or low charged molecules into a high vacuum environment. This makes it ideally suited to mass spectrometry. LIAD can be used with fragile biomolecules and very massive compounds alike. Here, we apply...
The phenomena occurring during laser–metal interaction depend on a variety of parameters such as laser wavelength, intensity, and thermophysical and optical properties of the irradiated material. This work comprises a detailed study of the perforation process of thin iron and steel plates under CW laser radiation at a wavelength of 1.07 μm. Experim...
Concerns that storage temperatures of drugs transported in veterinary practice vehicles may deviate from the range recommended in the summary of product characteristics have been raised. This study determined the actual temperatures in veterinary practice vehicles through every season of one year to identify risk factors and to give recommendations...
When probing the limits of quantum mechanics with methods of matter wave interferometry the demand for new sources with the ability to provide massive and complex particles arises. Soft laser assisted volatilisation techniques such as laser induced acoustic desorption (LIAD) are promising candidates for this task. In this thesis a LIAD-type source...
Understanding and quantifying the response of mountain glaciers to changing climate and weather conditions is a pressing task for climate scientists and glaciologists all over the world. To date, models that relate glacier mass and dynamics to atmospheric variations are well established. It has remained as a major challenge, however, to accurately describe the past, present and future atmospheric states that affect the glaciers. DoG systematically investigates the following research hypothesis: “The uncertainty in global and regional glacier simulations can be reduced significantly by reducing the uncertainty in the atmospheric drivers of the glacier simulations.” To test this hypothesis, DoG focuses at the development, application and rigorous validation of a state-of-the-art downscaling framework for glacierized mountain environments situated in a diversity of climatic and geo-environmental settings. This downscaling framework contains elements of the most modern statistical, as well as so-called hybrid downscaling techniques applied to reanalysis data predictors, for all atmospheric target variables required in process-based glacier mass balance models. The performance of the available global reanalysis data sets will be assessed for the purpose of glacier mass modelling, on a regionally differentiated view. Using in situ observations from stations near to- and on the glaciers, the transfer of the downscaling framework to glacierized mountain sites in various topographic and climate settings will be validated. This validation procedure pays particular attention to appropriately consider the pitfalls of short or patchy observation records that are often the only data source in remote mountains.