A global model study of natural bromine sources and the effects on tropospheric chemistry using MOZART4

Halogens in the atmosphere chemically destroy ozone. In the troposphere, bromine has higher ozone destruction efficiency than chlorine and is the halogen species with the widest geographical spread of natural sources. We investigate the relative strength of various sources of reactive tropospheric bromine and the influence of bromine on tropospheric chemistry using a 6-year simulation with the global chemistry transport model MOZART4. We consider the following sources: short-lived bromocarbons (CHBr3, CH2BrCl, CHBr2Cl, CHBrCl2, and CH2Br2) and CH3Br, bromine from airborne sea salt particles, and frost flowers and sea salt on or in the snowpack in polar regions. The total bromine emissions in our simulations add up to 31.7Gmol(Br)/yr: 63% from polar sources, 24.6% from short-lived bromocarbons and 12.4% from airborne sea salt particles. We conclude from our analysis that our global bromine emission is likely to be on the lower end of the range, because of too low emissions from airborne sea salt. Bromine chemistry has an effect on the oxidation capacity of the troposphere, not only due to its direct influence on ozone concentrations, but also by reactions with other key chemical species like HO x and NO x . Globally, the impact of bromine chemistry on tropospheric O3 is comparable to the impact of gas-phase sulfur chemistry, since the inclusion of bromine chemistry in MOZART4 leads to a decrease of the O3 burden in the troposphere by 6Tg, while we get an increase by 5Tg if gas-phase sulfur chemistry is switched off in the standard model. With decreased ozone burden, the simulated oxidizing capacity of the atmosphere decreases thus affecting species associated with the oxidation capacity of the atmosphere (CH3OOH, H2O2

Essays on the dynamics of inflation expectations

Defence date: 11 May 2022Examining Board : Prof. Evi Pappa (Universidad Carlos III Madrid); Prof. Leonardo Melosi (Federal Reserve Bank of Chicago); Dr. Philippe Andrade (Federal Reserve Bank of Boston); Dr. Marek Jarociński (European Central Bank)This thesis investigates the dynamics of inflation expectations with a particular focus on survey data. It aims to further the understanding of what drives inflation expectations and what are the implications of changes in inflation expectations for economic choices. The first chapter examines to what extent monetary policy moves household inflation expectations. More specifically, I study the effect of different types of monetary policy announcements on household inflation expectations based on micro data from a survey of German households. As unique feature, interviews of the survey were conducted both shortly before and after monetary policy events. This timing provides a natural experiment to identify the immediate effects of policy announcements on household inflation expectations. In contrast to most existing studies, the availability of the survey over a period of 15 years also allows me to exploit the time-series dimension to estimate how policy announcements affect household inflation expectations over the medium-term. I find that policy rate announcements lead to quick and significant adjustments in household inflation expectations with the effect peaking after half a year. Announcements about forward guidance and quantitative easing, on the other hand, have only small and delayed effects. My results suggest that monetary policy announcements can influence household expectations but further improvements in communication seem to be necessary to reach the general public more effectively. In particular, in an environment where policy rates are constrained by the effective lower bound, it may be very hard for central banks to influence household expectations. In the second chapter, joint with Evi Pappa and Alejandro Vicondoa, we focus on expectations about inflation in the medium to long run and study the implications of changes in these expectations for households’ economic choices. We identify in a SVAR shocks that best explain future movements in different measures of underlying inflation at a five-year horizon and label them as news augmented shocks to underlying inflation. Independently of the measure used, such shocks raise the nominal rate and inflation persistently, while they induce mild and short-lived increases in economic activity. The extracted inflation shocks have differential distributional effects. They increase significantly and persistently the consumption of mortgagors and homeowners. Differently from the traditional monetary policy disturbances, news augmented shocks to underlying inflation induce a positive wealth effect for mortgagors and homeowners, driven by a reduction in the real mortgage payments and a persistent increase in real house prices that they induce. The third chapter, joint with Jonas Fisher and Leonardo Melosi, is also about long-run inflation expectations but in this case the focus is on professional forecasters. We use panel data from the U.S. Survey of Professional Forecasters to estimate a model of individual forecaster behavior in an environment where inflation follows a trend-cycle time series process. Our model allows us to estimate the sensitivity of forecasters’ long-run expectations to incoming inflation and news about future inflation, and measure the coordination of beliefs about future inflation. We use our model of individual forecasters to study average long-run inflation expectations. Short term changes in inflation have small effects on average expectations; the sensitivity to news is over twice as large, but is still relatively small. These findings provide a partial explanation for why the anchoring and subsequent de-anchoring of average inflation expectations over 1991 to 2020 were such long-lasting episodes. Our model suggests coordination of beliefs also played a role, slowing down but not preventing the pull on average expectations from inflation running persistently below target. We apply our model to the case of a U.S. central banker setting policy in September 2021. Our results suggest the high inflation readings of mid-2021 would have to be followed by overshooting of the Fed’s target generally at the high end of the Fed’s Summary of Economic Projections to re-anchor long term expectations at their pre-Great Recession level.1 Central Bank Communication with the General Public: Survey Evidence from Germany 1.1 Introduction 1.2 Data and descriptive evidence 1.3 Identification approach and main results 1.4 Discussion 1.5 Inflation expectations and consumer spending 1.6 Conclusion 2 Uncovering the heterogeneous effects of news shocks to underlying inflation 32 2.1 Introduction 2.2 Identifying News Shocks to Underlying Inflation 2.3 Macroeconomic Effects 2.4 Estimation of Heterogeneous Effects 2.5 Comparison with Monetary Policy Shocksclusion 3 Anchoring long-run inflation expectations in a panel of professional forecasters 3.1 Introduction 3.2 Relation to the literature 3.3 The Model 3.4 Estimation 3.5 Data 3.6 Estimates 3.7 Inflation expectations through the lens of the model 3.8 Re-Anchoring U.S. Inflation Expectations 3.9 Conclusion -- References -- A Appendix to Chapter 1 -- A.1 GfK household survey -- A.2 Monetary policy surprises -- A.3 Additional event study results -- A.4 Additional local projection results -- A.5 Dynamic effects based on pseudo panel approach -- A.6 The effects on quantitative inflation expectations -- A.7 Financial market responses -- B Appendix to Chapter 2 -- B.1 Data Appendix -- B.2 Series of underlying inflation -- B.3 Correlation with monetary policy/inflation target shocks -- B.4 Validation of the Identified Shock -- B.5 IRFs Additional Variables -- B.6 VAR Robustness Analysis -- B.7 LP IRFs of VAR variables -- B.8 VAR IRFs of consumption responses by housing tenure -- B.9 Additional LP results -- B.10 Alternative dimensions of heterogeneity -- B.11 Robustness of Baseline Heterogeneous Effects -- B.12 Comparison with monetary policy shocks -- C Appendix to Chapter 3 -- C.1 Definition of matrices in subsection 3.3.2 and section 3.4 -- C.2 Model derivations -- C.3 Initial conditions for estimation -- C.4 Selection of forecasters -- C.5 Volatility of Expectations -- C.6 Historical decomposition -- C.7 Robustness of panel estimation -- C.8 Projection exercis

The immune gene repertoire encoded in the purple sea urchin genome

Echinoderms occupy a critical and largely unexplored phylogenetic vantage point from which to infer both the early evolution of bilaterian immunity and the underpinnings of the vertebrate adaptive immune system. Here we present an initial survey of the purple sea urchin genome for genes associated with immunity. An elaborate repertoire of potential immune receptors, regulators and effectors is present, including unprecedented expansions of innate pathogen recognition genes. These include a diverse array of 222 Toll-like receptor (TLR) genes and a coordinate expansion of directly associated signaling adaptors. Notably, a subset of sea urchin TLR genes encodes receptors with structural characteristics previously identified only in protostomes. A similarly expanded set of 203 NOD/NALP-like cytoplasmic recognition proteins is present. These genes have previously been identified only in vertebrates where they are represented in much lower numbers. Genes that mediate the alternative and lectin complement pathways are described, while gene homologues of the terminal pathway are not present. We have also identified several homologues of genes that function in jawed vertebrate adaptive immunity. The most striking of these is a gene cluster with similarity to the jawed vertebrate Recombination Activating Genes 1 and 2 (RAG1/2). Sea urchins are long-lived, complex organisms and these findings reveal an innate immune system of unprecedented complexity. Whether the presumably intense selective processes that molded these gene families also gave rise to novel immune mechanisms akin to adaptive systems remains to be seen. The genome sequence provides immediate opportunities to apply the advantages of the sea urchin model toward problems in developmental and evolutionary immunobiology

Massively Parallel RNA Sequencing Identifies a Complex Immune Gene Repertoire in the lophotrochozoan Mytilus edulis

The marine mussel Mytilus edulis and its closely related sister species are distributed world-wide and play an important role in coastal ecology and economy. The diversification in different species and their hybrids, broad ecological distribution, as well as the filter feeding mode of life has made this genus an attractive model to investigate physiological and molecular adaptations and responses to various biotic and abiotic environmental factors. In the present study we investigated the immune system of Mytilus, which may contribute to the ecological plasticity of this species. We generated a large Mytilus transcriptome database from different tissues of immune challenged and stress treated individuals from the Baltic Sea using 454 pyrosequencing. Phylogenetic comparison of orthologous groups of 23 species demonstrated the basal position of lophotrochozoans within protostomes. The investigation of immune related transcripts revealed a complex repertoire of innate recognition receptors and downstream pathway members including transcripts for 27 toll-like receptors and 524 C1q domain containing transcripts. NOD-like receptors on the other hand were absent. We also found evidence for sophisticated TNF, autophagy and apoptosis systems as well as for cytokines. Gill tissue and hemocytes showed highest expression of putative immune related contigs and are promising tissues for further functional studies. Our results partly contrast with findings of a less complex immune repertoire in ecdysozoan and other lophotrochozoan protostomes. We show that bivalves are interesting candidates to investigate the evolution of the immune system from basal metazoans to deuterostomes and protostomes and provide a basis for future molecular work directed to immune system functioning in Mytilus

How Useful Is a Linear Ozone Parameterization for Global Climate Modeling?

The explicit calculation of stratospheric ozone in global climate models still comes at a high computational cost. Here, the usefulness of a linear ozone parameterization in a global climate model is assessed by comparing it to an explicit chemistry scheme and to observations. It is shown that the annual mean total ozone column and the tropical ozone profile agree well for the linear and the explicit chemistry schemes and the observations. Ozone variability caused by the quasi-biennial oscillation and by extratropical quasi-stationary planetary waves is reproduced qualitatively, but its magnitude is underestimated in particular in the simulations using the linear parameterization. The response of ozone to a quadrupling of CO 2 simulated with both schemes is in the range of earlier simulations with explicit schemes. This concerns in particular ozone decreases in the tropical lower stratosphere and increases above predicted as a consequence of a strengthening of tropical upwelling and potentially affecting climate sensitivity. This study demonstrates that despite existing weaknesses a linear ozone parameterization can be a useful tool to represent stratospheric ozone in climate models at negligible computational cost

Skill, Correction, and Downscaling of GCM-Simulated Precipitation

The ability of general circulation models (GCMs) to correctly simulate precipitation is usually assessed by comparing simulated mean precipitation with observed climatologies. However, to what extent the skill in simulating average precipitation indicates how well the models represent temporal changes is unclear. A direct assessment of the latter is hampered by the fact that freely evolving climate simulations for past periods are not set up to reproduce the specific evolution of internal atmospheric variability. Therefore, model-to-real-world comparisons of time series of daily, monthly, or annual precipitation are not meaningful. Here, for the first time, the authors quantify GCM skill in simulating precipitation variability using simulations in which the temporal evolution of the large-scale atmospheric state closely matches that of the real world. This is achieved by nudging the atmospheric states in the ECHAM5 GCM, but crucially not the precipitation field itself, toward the 40-yr European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERA-40). Global correlation maps between observed and simulated seasonal precipitation allow areas in which simulated future precipitation changes are likely to be meaningful to be identified. In many areas, correlations higher than 0.8 are found. This means also that in these regions the simulated precipitation is a very good predictor for the true precipitation, and thus a statistical correction of the simulated precipitation, which can include a downscaling component, can provide useful estimates for local-scale precipitation. The authors show that a simple scaling of the simulated precipitation performs well in a cross validation and thus appears to be a promising alternative to standard statistical downscaling approaches

EPR Spectroscopy of MRI-Related Gd(III) Complexes: Simultaneous Analysis of Multiple Frequency and Temperature Spectra, Including Static and Transient Crystal Field Effects

For the first time, a very general theoretical method is proposed to interpret the full electron paramagnetic resonance (EPR) spectra at multiple temperatures and frequencies in the important case of S-state metal ions complexed in liquid solution. This method is illustrated by a careful analysis of the measured spectra of two Gd3+ (S = 7/2) complexes. It is shown that the electronic relaxation mechanisms at the origin of the EPR line shape arise from the combined effects of the modulation of the static crystal field by the random Brownian rotation of the complex and of the transient zero-field splitting. A detailed study of the static crystal field mechanism shows that, contrarily to the usual global models involving only second-order terms, the fourth and sixth order terms can play a non-negligible role. The obtained parameters are well interpreted in the framework of the physics of the various underlying relaxation processes. A better understanding of these mechanisms is highly valuable since they partly control the efficiency of paramagnetic metal ions in contrast agents for medical magnetic resonance imaging (MRI)