In a warming world, glaciers and ice sheets have an increasingly large influence on the environment, particularly through their contribution to sea level rise. Their response to anthropogenic climate change, in addition to natural variability, has a critical impact on dependent populations and will be key to predict future climates. Understanding the past natural transitions is also important as if the natural variability of the climate system is not well understood, we stand little change of accurately predicting future climate changes, especially in the context of rapid global warming. Ice cores represent the best time capsules for the recovery of paleo-climate informations. For that, the recovery of a suitable 1.5 million-year-old ice core in Antarctica is fundamental to better understand the natural climate reorganisation which occurred between 0.9 and 1.2 Ma. Constraining the englacial and basal temperature evolution of glaciers and ice sheets through time is the first step in understanding their temporal stability and therefore potential impacts on climate. Furthermore, obtaining the best constraints on basal conditions is essential as such million-year-old ice will be located very near to the bedrock, where the thermal regime has the strongest impact. However, measurements of current englacial and basal temperature have only been obtained at a few drill sites for glaciers and ice sheets. We must therefore turn to thermodynamical models to provide theoretical and statistical constraints on governing thermal processes. Thermodynamical models rely on a suite of governing equations, which we describe in this thesis. Our first study area is the McCall glacier, in Alaska (USA), where we show that the glacier cooled down in the warming climate of the last 50 years using a 1D thermodynamical model. We calculate the present-day englacial temperature distribution using recently acquired data in the form of englacial temperature measurements and radio-echo sounding surveys of the glacier. We show the important of absence of latent heat release due to the refreezing of meltwater inside an active surface layer and reconstruct the last 50 years of equilibrium line altitude (ELA) elevation changes. In the context of Beyond Epica Oldest Ice, a European project aimed at recovering a 1.5 million year-old ice core, we propose for the first time a map of the location of adequate drilling sites for the entire Antarctic Ice Sheet. We use a 3D thermomechanical model to calculate a new basal temperature map of the Antarctic Ice Sheet, as well as a 1D thermodynamical model to constrain the poorly known geothermal heat flux (GHF). These combined model runs use the latest acquired data sets for the GHF, ice flow velocity, ice thickness and subglacial lakes. In order to take into account 2 Ma of Antarctic climate history, we use a transient 1D thermodynamical model to provide constraints on GHF by calculating the maximum value of GHF allowed to keep frozen basal conditions everywhere underneath the ice sheet. These values are then statistically compared to published GHF data sets to propose a probabilistic map of frozen and thawed bedrock locations. This transient model uses high spatial resolution radar data acquired over the Dome Fuji and Dome C regions to examine their likelihood of having preserved 1.5-million-year ice. We define a number of important criteria such as GHF, bedrock variability, ice thickness and other parameter values for Oldest Ice survival. We anticipate that our methods will be highly relevant for Oldest Ice prospection in other areas of the ice sheet that so far remain little or un-surveyed, as well as for the thermal modelling of other glaciers and ice sheets, and in particular, of the Greenland Ice Sheet. / Doctorat en Sciences / info:eu-repo/semantics/nonPublished

Isostasy is a key concept in geoscience to interpret the state of mass balance between the Earth’s crust and mantle. There are four well-known isostatic models: the classical models of Airy/Heiskanen (A/H), Pratt/Hayford (P/H), and Vening Meinesz (VM) and the modern model of Vening Meinesz-Moritz (VMM). The first three models assume a local and regional isostatic compensation, whereas the latter one supposes a global isostatic compensation scheme. A more satisfactory test of isostasy is to determine the Moho interface. The Moho discontinuity (or Moho) is the surface, which marks the boundary between the Earth’s crust and upper mantle. Generally, the Moho interface can be mapped accurately by seismic observations, but limited coverage of seismic data and economic considerations make gravimetric or combined gravimetric-seismic methods a more realistic technique for imaging the Moho interface either regional or global scales. It is the main purpose of this dissertation to investigate an isostatic model with respect to its feasibility to use in recovering the Moho parameters (i.e. Moho depth and Moho density contrast). The study is mostly limited to the VMM model and to the combined approach on regional and global scales. The thesis briefly includes various investigations with the following specific subjects: 1) to investigate the applicability and quality of satellite altimetry data (i.e. marine gravity data) in Moho determination over the oceans using the VMM model, 2) to investigate the need for methodologies using gravimetric data jointly with seismic data (i.e. combined approach) to estimate both the Moho depth and Moho density contrast over regional and global scales, 3) to investigate the spherical terrain correction and its effect on the VMM Moho determination, 4) to investigate the residual isostatic topography (RIT, i.e. difference between actual topography and isostatic topography) and its effect in the VMM Moho estimation, 5) to investigate the application of the lithospheric thermal-pressure correction and its effect on the Moho geometry using the VMM model, 6) Finally, the thesis ends with the application of the classical isostatic models for predicting the geoid height. The main input data used in the VMM model for a Moho recovery is the gravity anomaly/disturbance corrected for the gravitational contributions of mass density variation due in different layers of the Earth’s crust (i.e. stripping gravity corrections) and for the gravity contribution from deeper masses below the crust (i.e. non-isostatic effects). The corrections are computed using the recent seismic crustal model CRUST1.0. Our numerical investigations presented in this thesis demonstrate that 1) the VMM approach is applicable for estimating Moho geometry using a global marine gravity field derived by satellite altimetry and that the possible mean dynamic topography in the marine gravity model does not significantly affect the Moho determination, 2) the combined approach could help in filling-in the gaps in the seismic models and it also provides good fit to other global and regional models more than 90 per cent of the locations, 3) despite the fact that the lateral variation of the crustal depth is rather smooth, the terrain affects the Moho result most significantly in many areas, 4) the application of the RIT correction improves the agreement of our Moho result with some published global Moho models, 5) the application of the lithospheric thermal-pressure correction improves the agreement of VMM Moho model with some other global Moho models, 6) the geoid height cannot be successfully represented by the classical models due to many other gravitational signals from various mass variations within the Earth that affects the geoid. / <p>QC 20160317</p>

The thesis deals with evaluation of the environmental thermal state in closed rooms with people inside the room. The achievement of thermal comfort is related to thermal balance of human body. People are producing heat during their work, which has to be carried away from the body to surrounding area by radiation, convection, conduction, respiration and evaporation. The intensity of heat removal is influenced by environmental parameters, especially by air temperature, mean radiant temperature, air velocity and humidity. Personal factors as energy expenditure of human body and clothing resistance are influencing the intensity of heat removal as well. People are able to influence the thermal comfort by their behaviour in given environment, appropriate clothing and regulation of basic environmental parameters. CSN EN ISO 7730 standard states that environmental parameters should be estimated or measured. The operative temperature is than evaluated from collected data. This operative temperature is defined as the temperature of black enclosed area where the human body will be by convection and radiation sharing the same amount of heat as in real inconsistent environment. Nowadays on the market there is no cheap solution for sensor which is able to evaluate the operating temperature and could be used in buildings. There are a lot of professional sensors which have very high accuracy, but are very expensive. Therefore are mainly used only for research or for single and exceptional measurement of environmental thermal state in rooms. The thesis is therefore focused on proposal of suitable (compact) operative temperature sensor assembled according to valid regulations and standards. Emphasis is placed mainly on the sensor price together with guarantee of sufficient accuracy. The proposed sensor is providing information to control system which is than able to adjust the parameters of environment using appropriate way based on relevant requirements. Here is some space for energy savings due to possible continuous measurement and evaluation of environmental thermal state in different rooms. Therefore, during continuous measurement no unnecessary rooms overheating in winter as well as unreasonable cooling in summer should occur. This research and solution is than reflected in reduction of energy consumption used for building operation and subsequently reduction of the pollutants production. This issue is being watched with increasing interest. Another advantage is that whole system is able to work autonomously without human intervention. People no longer have to continuously adjust air temperature because the control system is able to evaluate the most appropriate adjustments based on objective data obtained from the sensor. The thesis includes subsequent verification of proposed sensor as well as the definition of sensor technical parameters including analysis of measurement uncertainties.

Teplota vzduchu je nejčastěji používaná k posouzení tepelného stavu vnitřního prostředí. Avšak teplota vzduchu sama o sobě, je v mnoha případech pro toto posouzení nedostatečná. Hlavním cílem disertační práce je vyhodnotit tepelný stav vnitřního prostředí a specifikovat parametry, které na něj mají vliv. Teplota vzduchu, střední radiantní teplota, rychlost vzduchu a vlhkost vzduchu jsou čtyři základní parametry, které určují tepelný stav vnitřního prostředí. Vzhledem k tomu, že tepelný stav prostředí závisí na mnoha aspektech, byly odvozeny veličiny, které zahrnují kombinovaný účinek několika nebo všech těchto parametrů k určení tepelného stavu prostředí. Jedná se např. o efektivní teplotu, teplotu kulového teploměru, operativní teplotu, ekvivalentní teplotu, PMV a PPD indexy... aj. V dnešní době existuje spousta vysoce přesných senzorů, které mohou zhodnotit tepelný stav vnitřního prostředí. Z důvodu jejich vysoké ceny jsou používané převážně pro účely výzkumu. Předkládaná práce se převážně soustředí na vývoj kompaktního deskového senzoru pro vyhodnocení tepelného stavu vnitřního prostředí. Zaměřuje se hlavně na nízkou cenu senzoru společně s dostatečnou přesností. K dosažení cíle této práce jsou provedeny následující postupy: • Analýza environmentálních faktorů ovlivňujících tepelný stav prostředí. • Studium dopadu teploty vzduchu, střední radiantní teploty a rychlosti proudění vzduchu na tepelné indexy: teplotu kulového teploměru a operativní teplotu. • Teoretické porovnání teploty kulového teploměru a operativní teploty. • Navržení, rozvoj a konstrukce nového deskového senzoru pro posouzení tepelného stavu vnitřního prostředí. • Navržení a konstrukce testovací komory pro porovnávání senzorů tepelného stavu prostředí. • Kalibrace zkonstruovaného senzoru měřením fyzikálních veličin charakterizujících tepelný stav prostředí. • Testy směrové závislosti vyvinutého deskového senzoru a porovnání s kulovým teploměrem v testovací komoře. • Srovnání teoretických řešení s provedenými měřeními v testovací komoře. Výsledkem této práce je vlastní teoretické srovnání teploty kulového teploměru a operativní teploty ve vybraném rozsahu teploty vzduchu, střední radiantní teploty a rychlosti vzduchu pro možnost hodnocení tepelného stavu vnitřního prostředí pomocí kulového teploměru. Hlavním výstupem je však navržení a zhotovení jednoduchého deskového senzoru, který by byl dostatečně přesný pro měření tepelného stavu prostředí. V rámci disertace byla postavena také testovací komora a bylo provedeno testování vyvinutého senzoru pomocí měřicího systému INNOVA.

The thesis deals with evaluation of the environmental thermal state in closed rooms with people inside the room. The achievement of thermal comfort is related to thermal balance of human body. People are producing heat during their work, which has to be carried away from the body to surrounding area by radiation, convection, conduction, respiration and evaporation. The intensity of heat removal is influenced by environmental parameters, especially by air temperature, mean radiant temperature, air velocity and humidity. Personal factors as energy expenditure of human body and clothing resistance are influencing the intensity of heat removal as well. People are able to influence the thermal comfort by their behaviour in given environment, appropriate clothing and regulation of basic environmental parameters. CSN EN ISO 7730 standard states that environmental parameters should be estimated or measured. The operative temperature is than evaluated from collected data. This operative temperature is defined as the temperature of black enclosed area where the human body will be by convection and radiation sharing the same amount of heat as in real inconsistent environment. Nowadays on the market there is no cheap solution for sensor which is able to evaluate the operating temperature and could be used in buildings. There are a lot of professional sensors which have very high accuracy, but are very expensive. Therefore are mainly used only for research or for single and exceptional measurement of environmental thermal state in rooms. The thesis is therefore focused on proposal of suitable (compact) operative temperature sensor assembled according to valid regulations and standards. Emphasis is placed mainly on the sensor price together with guarantee of sufficient accuracy. The proposed sensor is providing information to control system which is than able to adjust the parameters of environment using appropriate way based on relevant requirements. Here is some space for energy savings due to possible continuous measurement and evaluation of environmental thermal state in different rooms. Therefore, during continuous measurement no unnecessary rooms overheating in winter as well as unreasonable cooling in summer should occur. This research and solution is than reflected in reduction of energy consumption used for building operation and subsequently reduction of the pollutants production. This issue is being watched with increasing interest. Another advantage is that whole system is able to work autonomously without human intervention. People no longer have to continuously adjust air temperature because the control system is able to evaluate the most appropriate adjustments based on objective data obtained from the sensor. The thesis includes subsequent verification of proposed sensor as well as the definition of sensor technical parameters including analysis of measurement uncertainties.

The Ph.D. thesis deals with the evaluation of indoor thermal environment in which people are located. A great attention is paid to the thermal comfort. If a person in a given environment does not feel well, then makes mistakes. Thermal comfort is created many parameters that can be monitored and managed. These parameters include not only temperature but also other parameters such as the mean radiant temperature, operative temperature, humidity and air velocity and the draft. All these parameters can be measured. The standard ČSN EN ISO 7726 is written how and what the parameters are measured. Furthermore, this standard provides requirements for measuring equipment. There are many professional measuring devices. Unfortunately, these devices are very expensive. Therefore are within the project GACR 101/09/H050 - Research on energy- saving equipment to achieve the quality of the indoor environment at our faculty developed sensors for thermal comfort, which have showed comparable accuracy measurements as a professional , but it will be cheaper than professional. Knowledge of real parameters of the developed sensor thermal comfort environment is important, as with any other measurement devices, and also need to verified whether it has the required accuracy. In order to objectively sensors testing were developed two chambers - the testing and calibration chamber. The developed sensors were tested both in the open laboratory, and also in the test chamber. Then uncertainties measurement were calculated from the results of measurements This work deals with the evaluation of thermal comfort, the measurement of parameters of thermal environment, the evaluating the results of measurements and determining the measurement uncertainty of the sensors. In this thesis, based on these results, were recommended suitable sensors for measuring various parameters environment.