Adaptive MCMC methods with applications in environmental and geophysical models

This work presents new, efficient Markov chain Monte Carlo (MCMC) simulation methods for statistical analysis in various modelling applications. When using MCMC methods, the model is simulated repeatedly to explore the probability distribution describing the uncertainties in model parameters and predictions. In adaptive MCMC methods based on the Metropolis-Hastings algorithm, the proposal distribution needed by the algorithm learns from the target distribution as the simulation proceeds. Adaptive MCMC methods have been subject of intensive research lately, as they open a way for essentially easier use of the methodology. The lack of user-friendly computer programs has been a main obstacle for wider acceptance of the methods. This work provides two new adaptive MCMC methods: DRAM and AARJ. The DRAM method has been built especially to work in high dimensional and non-linear problems. The AARJ method is an extension to DRAM for model selection problems, where the mathematical formulation of the model is uncertain and we want simultaneously to fit several different models to the same observations. The methods were developed while keeping in mind the needs of modelling applications typical in environmental sciences. The development work has been pursued while working with several application projects. The applications presented in this work are: a winter time oxygen concentration model for Lake Tuusulanjärvi and adaptive control of the aerator; a nutrition model for Lake Pyhäjärvi and lake management planning; validation of the algorithms of the GOMOS ozone remote sensing instrument on board the Envisat satellite of European Space Agency and the study of the effects of aerosol model selection on the GOMOS algorithm.

The Janus-faced City: A Sensory History of the London Blitz 1940–1941

The city of London was, during the years of 1940–1941, a city under fire. The metropolis seemed to have two faces, like the Roman deity Janus: the face of the daylight hours, so normal, and yet so deceiving in its false quietness – and at nightfall, the city turned, and the face of it was the face of the devil himself, transforming London into a living inferno. This thesis examines the sensescapes of the Blitz, through the diaries and memoirs written of that time. The primary sources consist of seven different diaries, two autobiographies, and four research volumes that contain multiple diary- and memoire entries, mostly from the Mass Observation Archives and from the Imperial War Museum. The sensory approach is a new orientation in the field of history – it studies the five senses in their cultural contexts, interpreting the often subtle ways in which the senses affect into society, politics, culture, and class hierarchies, to name only but few. The subject of the sensory history of war is a theme widely unexamined: this thesis contributes to this frontier field by unveiling the sensorium of the London bombings, comparing the differences between the halves of nychtemeron, and examining how the Blitz was communicated by the writers as a lived, bodily experience. This study reveals the very different sensory worlds in which the Londoners lived, during a time that is often described with the mythical solidarity that was thought to exist between the people. The reality of the homeless, working class, and poor were in the foul smelling tubes, poor law -dated rations, and in the smoking ruins of East End – the contrast was massive reflecting it to the luxury hotels and restaurants of the upper classes, opportunities for evacuation, sheltering possibilities, and overall comforts of life.