Stochastic climate theory and modeling

Stochastic methods are a crucial area in contemporary climate research and are increasingly being used in comprehensive weather and climate prediction models as well as reduced order climate models. Stochastic methods are used as subgrid-scale parameterizations (SSPs) as well as for model error representation, uncertainty quantification, data assimilation, and ensemble prediction. The need to use stochastic approaches in weather and climate models arises because we still cannot resolve all necessary processes and scales in comprehensive numerical weather and climate prediction models. In many practical applications one is mainly interested in the largest and potentially predictable scales and not necessarily in the small and fast scales. For instance, reduced order models can simulate and predict large-scale modes. Statistical mechanics and dynamical systems theory suggest that in reduced order models the impact of unresolved degrees of freedom can be represented by suitable combinations of deterministic and stochastic components and non-Markovian (memory) terms. Stochastic approaches in numerical weather and climate prediction models also lead to the reduction of model biases. Hence, there is a clear need for systematic stochastic approaches in weather and climate modeling. In this review, we present evidence for stochastic effects in laboratory experiments. Then we provide an overview of stochastic climate theory from an applied mathematics perspective. We also survey the current use of stochastic methods in comprehensive weather and climate prediction models and show that stochastic parameterizations have the potential to remedy many of the current biases in these comprehensive models

Assessing bulk carbonates as archives for seawater Li isotope ratios

Silicate weathering is a primary control on the carbon cycle and therefore long-term climate. Tracing silicate weathering in the geological record has been a challenge for decades, with a number of proxies proposed and their limits determined. Recently lithium isotopes in marine carbonates have emerged as a potential tracer. Bulk carbonates are increasingly being used as a Li isotope archive, though with limited tests thus far of the robustness of this approach in the modern ocean. As the bulk composition of marine pelagic carbonates has changed through time and geographically, assessing the fidelity of bulk carbonate as proxy carrier is fundamental. To address the impact of compositional variability in bulk carbonate on Li isotopes, we examine 27 Bahamian aragonitic bulk carbonates and 16 Atlantic largely calcitic core-top sediment samples. Two core-tops only have trace (<10 %) carbonate, and are analysed to test whether carbonates in such sections are still a viable archive. We selectively extract the exchangeable and carbonate fractions from the core-top samples. The exchangeable fraction contains ∼2 % of the total Li and has a fairly constant offset from seawater of 16.5 ± 0.8‰. When leaching silicate-containing carbonates, acetic acid buffered with sodium acetate appears a more robust method of solely attacking carbonates compared to dilute HCl, which may also liberate some silicate-bound Li. Carbonates from samples that do not contain aragonite have the isotopic fractionation of seawater of Δ7Liseawater-calcite = 6.1 ± 1.3‰ (2sd), which is not affected by latitude or the water depth the sample was deposited at. The pure aragonite bulk carbonates from the Bahamas have a fractionation of Δ7Liseawater-aragonite = 9.6 ± 0.6‰. A sediment sample from the Galician coast that mostly consists of quartz is highly offset from seawater by ∼20‰ and also has relatively high Li/Ca ratios. These high values are not due to leaching of silicate material directly (Al/Ca ratios are low). We interpret this addition via cation exchange of Li from silicate during recrystallisation. Overall bulk carbonates from the open ocean are a reliable archive of seawater δ7Li, but care must be taken with carbonate mineralogy and low-carbonate samples. Overall, therefore, any examination of the palaeo-seawater δ7Li record must be reproduced in different global settings (e.g. multiple global cores) before it can be considered robust

A Land Suitability Study for Lakewood Township in St. Louis County, Minnesota

A Plan B Paper submitted to the faculty of the Graduate School of the University of Minnesota by Heinz Berner as a Requirement for the Degree Master of Science, May 1977.The purpose of this paper is to provide opportunity for a practical exercise in regional planning. It must be emphasized that this paper is a report rather than an original planning contribution. Fieldwork other than four reconnaissance trips was not undertaken. Instead, data compilation has been achieved through personal consultation of local planning offices and governmental agencies as well as literature research. However, content and format (including graphical representation) are the result of the writer's work and judgement

Geologic Processes and Hazards in High-Relief Terrain

A Plan B Paper submitted to the faculty of the Graduate School of the University of Minnesota by Heinz Berner as a Requirement for the Degree Master of Science, July 1977.The content of this paper summarizes the principles of glacial processes and some aspects of mass movement in mountain regions such as the Alps. Especially avalanche formation and protective measures as practiced in Switzerland shall be discussed. The purpose of this report is to review some surficial geologic processes in high-relief terrain and see how they affect human developments and activities. It is thus, too, a practical exercise in environmental geology, particularly as it relates to land use planning. Furthermore, it is a library research paper required for graduation

Holographic Quantitative Structure-Activity Relationships of Tryptamine Derivatives at NMDA, 5HT1A and 5HT2A Receptors

molecule

Data from: Genetic architecture of skeletal evolution in European lake and stream stickleback

Advances in genomic techniques are greatly facilitating the study of molecular signatures of selection in diverging natural populations. Connecting these signatures to phenotypes under selection remains challenging, but benefits from dissections of the genetic architecture of adaptive divergence. We here perform quantitative trait locus (QTL) mapping using 488 F2 individuals and 2011 single nucleotide polymorphisms (SNPs) to explore the genetic architecture of skeletal divergence in a lake-stream stickleback system from Central Europe. We find QTL for gill raker, snout, and head length, vertebral number, and the extent of lateral plating (plate number and height). Although two large-effect loci emerge, QTL effect sizes are generally small. Examining the neighborhood of the QTL-linked SNPs identifies several genes involved in bone formation, which emerge as strong candidate genes for skeletal evolution. Finally, we use SNP data from the natural source populations to demonstrate that some SNPs linked to QTL in our cross also exhibit striking allele frequency differences in the wild, suggesting a causal role of these QTL in adaptive population divergence. Our study paves the way for comparative analyses across other (lake-stream) stickleback populations, and for functional investigations of the candidate genes

Data from: Genetic architecture of skeletal evolution in European lake and stream stickleback

Advances in genomic techniques are greatly facilitating the study of molecular signatures of selection in diverging natural populations. Connecting these signatures to phenotypes under selection remains challenging, but benefits from dissections of the genetic architecture of adaptive divergence. We here perform quantitative trait locus (QTL) mapping using 488 F2 individuals and 2011 single nucleotide polymorphisms (SNPs) to explore the genetic architecture of skeletal divergence in a lake-stream stickleback system from Central Europe. We find QTL for gill raker, snout, and head length, vertebral number, and the extent of lateral plating (plate number and height). Although two large-effect loci emerge, QTL effect sizes are generally small. Examining the neighborhood of the QTL-linked SNPs identifies several genes involved in bone formation, which emerge as strong candidate genes for skeletal evolution. Finally, we use SNP data from the natural source populations to demonstrate that some SNPs linked to QTL in our cross also exhibit striking allele frequency differences in the wild, suggesting a causal role of these QTL in adaptive population divergence. Our study paves the way for comparative analyses across other (lake-stream) stickleback populations, and for functional investigations of the candidate genes