Sequential data assimilation methods for atmospheric general circulation models

The data assimilation (DA) process has gained some spotlight in recent years as computers have become more powerful, and models more complex. Even so, most natural phenomena have many correlations among variables that are very challenging to capture. In this proposal, we discuss the impact of an intermediate step in the leaping strategy used as a numerical integrator for Atmospheric General Circulation Models during the assimilation process, and its explicit update, particularly, for the Simplified Parameterizations, privitivE-Equation DYnamics model, nicknamed as SPEEDY. Using literature validated formulations of the Ensemble Kalman Filters the Local Ensemble Kalman Filter (LEnKF), Local Ensemble Transform Kalman Filter (LETKF), and the Ensemble Kalman Filter based on a Modified Cholesky Decomposition (EnKF-MC) experimental test are performed using the leaping step in the update process, and using only the forecast step, and letting the model propagate the updates. For the EnKF-MC formulation, we propose a formulation onto the observations space. As well, we present an intuitive Python package to perform sequential data assimilation on atmospheric general circulation models. We denote our package by Applied Math and Computer Science Lab - Data Assimilation AMLCS-DA. This package contains the efficient implementations of the previously mentioned formulations. The results reveal that our proposed framework can properly estimate model variables within reasonable accuracies in terms of Root-Mean-Square-Error when we update only the forecast state, even when using sparse operational observators (25%, 11%, 6%, 4%).MaestríaMagister en Ingeniería de Sistemas y Computació

Statistical Downscaling For The Northern Great Plains: A Comparison Of Bias Correction And Redundancy Analysis

The climate of the Earth is changing, and is primarily a result of our rampant industrialization over the past two centuries. These changes have manifested themselves in many ways over the whole of the Earth’s surface and sub-systems, leading to the need to understand the changes and predict future outcomes. Coupled climate and general circulation - Earth system models (GCMs) allow for the analysis of dynamically active simulations over the whole of the planet, yet are limited by computational power. The model grids are coarse by design to perform within these computational constraints, which enables them to function and provide information at continental and larger scales, but which limit their ability to offer information for regional and local environments. Dynamical models created with higher resolutions allow for regional climate modeling yet are also limited by computational constraints and require detailed information to run. Statistical downscaling seeks to bridge the gap between coarse GCM grids by utilizing observational data and statistical models to remove the biases from the data at the local level. There have been several types of statistical methods applied to this task over many different regions with some success. The goal of this study is to utilize two methods in particular, bias-corrected spatial disaggregation (BCSD) and redundancy analysis (RDA), to downscale maximum and minimum temperature, as well as precipitation, for the Northern Great Plains (NGP) region. These methods are calibrated over the period 1950 – 1970 using a 1/8 degree gridded dataset for 17 GCMs, then applied to a verification period (1970 – 1999) and compared to observations over that period to assess the downscaled models skill in capturing local NGP variability. These methods are also applied to future model runs forced via the representative concentration pathways (RCPs) low end (2.6), median (4.5) and high end (8.5) 21st Century forcings, which provides possible outlooks for local stakeholders over the coming decades. It is found that BCSD does well in downscaling temperature and precipitation, as well as their various metrics. RDA provides more mixed success, with good skill demonstrated for temperatures but a strong wet bias in precipitation. It is noted, however, that RDA yielded better correlations to the observations. Future scenarios show broad ranges of projected outcomes that, as expected, increase with increasing forcing, though temperature shows stronger changes than precipitation, and BCSD exhibits higher sensitivity than RDA. Future research may help further constrain the results of these downscaling methods, particularly RDA, by adopting further bias correction to the results

Climate change and impacts in the urban systems

A thesis submitted in partial fulfillment of the requirements for the degree of Doctor in Information Management, specialization in Geographic Information SystemsUrban systems are not only major drivers of climate change, but also impact hotspots. The processes of global warming and urban population growth make our urban agglomerations vulnerable to chain reactions triggered by climate related hazards. Hence, the reliable and cost-effective assessment of future climate impact is of high importance. Two major approaches emerge from the literature: i) detailed spatially explicit assessments, and ii) more holistic approaches consistently assessing multiple cities. In this multidisciplinary thesis both approaches were addressed. Firstly, we discuss the underlying reasons and main challenges of the applicability of downscaling procedures of climate projections in the process of urban planning. While the climate community has invested significant effort to provide downscaling techniques yielding localised information on future climate extreme events, these methods are not widely exploited in the process of urban planning. The first part of this research attempts to help bridge the gap between the communities of urban planners and climatologists. First, we summarize the rationale for such cooperation, supporting the argument that the spatial scale represents an important linkage between urban and climate science in the process of designing an urban space. Secondly, we introduce the main families of downscaling techniques and their application on climate projections, also providing the references to profound studies in the field. Thirdly, special attention is given to previous works focused on the utilization of downscaled ensembles of climate simulations in urban agglomerations. Finally, we identify three major challenges of the wider utilization of climate projections and downscaling techniques, namely: (i) the scale mismatch between data needs and data availability, (ii) the terminology, and (iii) the IT bottleneck. The practical implications of these issues are discussed in the context of urban studies. The second part of this work is devoted to the assessment of impacts of extreme temperatures across the European capital cities. In warming Europe, we are witnessing a growth in urban population with aging trend, which will make the society more vulnerable to extreme heat waves. In the period 1950-2015 the occurrence of extreme heat waves increased across European capitals. As an example, Moscow was hit by the strongest heat wave of the present era, killing more than ten thousand people. Here we focus on larger metropolitan areas of European capitals. By using an ensemble of eight EURO-CORDEX models under the RCP8.5 scenario, we calculate a suite of temperature based climate indices. We introduce a ranking procedure based on ensemble predictions using the mean of metropolitan grid cells for each capital, and socio-economic variables as a proxy to quantify the future impact. Results show that all the investigated European metropolitan areas will be more vulnerable to extreme heat in the coming decades. Based on the impact ranking, the results reveal that in near, but mainly in distant future, the extreme heat events in European capitals will be not exclusive to traditionally exposed areas such as the Mediterranean and the Iberian Peninsula. Cold waves will represent some threat in mid of the century, but they are projected to completely vanish by the end of this century. The ranking of European capitals based on their vulnerability to the extreme heat could be of paramount importance to the decision makers in order to mitigate the heat related mortality. Such a simplistic but descriptive multi-risk urban indicator has two major uses. Firstly, it communicates the risk associated with climate change locally and in a simple way. By allowing to illustratively relate to situations of other capitals, it may help to engage not only scientists, but also the decision makers and general public, in efforts to combat climate change. Secondly, such an indicator can serve as a basis to decision making on European level, assisting with prioritizing the investments and other efforts in the adaptation strategy. Finally, this study transparently communicates the magnitude of future heat, and as such contributes to raise awareness about heat waves, since they are still often not perceived as a serious risk. Another contribution of this work to communication of consequences of changing climate is represented by the MetroHeat web tool, which provides an open data climate service for visualising and interacting with extreme temperature indices and heat wave indicators for European capitals. The target audience comprises climate impact researchers, intermediate organisations, societal-end users, and the general public

Meteorological phenomena on Mars studied with Mars Express VMC images

175 p.En esta tesis se estudian varios fenómenos meteorológicos que tienen lugar en la atmósfera de Marte con imágenes de la cámara VMC de Mars Express. Otros instrumentos que vuelan en misiones en órbita de Marte se utilizan como soporte. Como parte de la tesis, se han desarrollado nuevas metodologías de trabajo que han implicado la operación de VMC, su calibrado, y la preparación de pipelines de procesado de datos.Los fenómenos meteorológicos que se estudian en esta tesis son tres: 1. Las nubes crepusculares noctilucentes en Marte. 2. La nube elongada de Arsia Mons (AMEC). 3. La gran tormenta global de Marte de 2018 en su penetración hacia la región polar sur.Como parte de la tesis se ha desarrollado el primer estudio sistemático de nubes noctilucentes en Marte, determinando por primera vez su distribución geográfica y temporal. También se ha descrito por primera vez en la literatura científica la AMEC, un fenómeno meteorológico extraordinario para el que también se ha dado un principio de explicación con la ayuda de un modelo numérico de mesoescala. El estudio de esta nube de origen orográfico ha llevado a conclusiones novedosas sobre la formación de nubes orográficas en Marte. Por último, el estudio de la gran tormenta de 2018 muestra vientos del vórtice polar sur que no son enteramente coincidentes con los predichos por los modelos de circulación general

A strategy for Earth science from space in the 1980s. Part 1: Solid earth and oceans

The report develops a ten-year science strategy for investigating the solid earth and dynamics of world oceans from Earth orbit. The strategy begins from the premise that earth studies have proceeded to the point where further advances in understanding Earth processes must be based on a global perspective and that the U.S. is technically ready to begin a global study approach from Earth orbit. The major areas of study and their fundamental problems are identified. The strategy defines the primary science objectives to be addressed and the essential measurements and precision to achieve them

Management and display of four-dimensional environmental data sets using McIDAS

Over the past four years, great strides have been made in the areas of data management and display of 4-D meteorological data sets. A survey was conducted of available and planned 4-D meteorological data sources. The data types were evaluated for their impact on the data management and display system. The requirements were analyzed for data base management generated by the 4-D data display system. The suitability of the existing data base management procedures and file structure were evaluated in light of the new requirements. Where needed, new data base management tools and file procedures were designed and implemented. The quality of the basic 4-D data sets was assured. The interpolation and extrapolation techniques of the 4-D data were investigated. The 4-D data from various sources were combined to make a uniform and consistent data set for display purposes. Data display software was designed to create abstract line graphic 3-D displays. Realistic shaded 3-D displays were created. Animation routines for these displays were developed in order to produce a dynamic 4-D presentation. A prototype dynamic color stereo workstation was implemented. A computer functional design specification was produced based on interactive studies and user feedback

Modeling and simulation facility: Research review, 1980 - 1981

General circulation modeling studies related to global atmospheric and oceanic research are presented