Fast Response of Boundary Layer Clouds to Climate Change

Boundary layer clouds make up a large part of the total cloud cover across the world. These clouds play an important role in the vertical transport of heat, moisture, and momentum from the surface through the boundary layer. Thus these clouds have a significant impact on the vertical structure of the boundary layer. They not only have an impact on the vertical structure, but also have a significant impact on the Earth's radiation budget. Normally boundary layer clouds generally have a higher albedo compared to the surface below them and as a result there is an increased reflectance of solar radiation. Due to these strong impacts on the atmospheric conditions it is important that these boundary layer clouds and their processes are taken into account when simulating (future) climates. One of the largest uncertainties in climate projections is related to the uncertainty in how boundary layer clouds respond to climate change. This uncertainty in cloud feedback is primarily related to the use of general circulation models (GCMs) in climate projections. As GCMs have a very coarse resolution they require parameterizations to represent boundary layer processes and clouds. These parameterizations are imperfect and therefore the GCMs have difficulties in representing the radiative effects of clouds. Therefore high resolution models such as large-eddy simulations (LESs), which require less parameterizations are used to study boundary layer processes and clouds. Several LES studies have been conducted on climate projections, where a perturbation of a future climate is applied to the model. These perturbations include increases in sea surface temperature and/or the concentration of CO2. In future climates it is anticipated that the atmosphere will become warmer and therefore it can contain a much larger concentration of moisture. This increased moisture can lead to the presence of very humid layers above the boundary layer, known as elevated moisture layers, which have already been observed in nature. This thesis investigates the response of boundary layer clouds to the presence of an elevated moisture layer, based on observed conditions during research flight 4 of the first Next Generation-aircraft Remote-sensing (NARVAL) campaign. This study is divided into three main sections. The first and second parts of the analysis focus on comparing the LES to observations recorded during the campaign in order to test the representativeness of the model. Following this the response of boundary layer clouds to an elevated moisture layer perturbation is investigated. To this purpose, LESs are initially generated at the locations of the 11 dropsondes launched during the fourth research flight of the NARVAL campaign, which took place on December 14th 2013. Initial comparisons indicate the LES shows good ability in representing the atmospheric conditions observed, showing a strong evolution of the boundary layer over time which has previously been observed at the Barbados Cloud Observatory. The results from the simulations also indicate that the LES has an ability to capture the height of the boundary layer inversion. There are some limitations in capturing the strength of the inversion, which is potentially related to the extremely dry conditions observed above the boundary layer. The LES is then compared to retrievals from the High Altitude and Long Range Aircraft (HALO) Microwave Package (HAMP) instrument. In order to take the flight path into account the mean large-scale profiles, from the locations of 9 dropsondes, are used to derive a composite case. The aim of using the composite case was to investigate whether the LES has the ability to capture the large variability in the integrated water vapor and liquid water path retrieved throughout the flight path. Using a large domain LES, with horizontal extent reaching 51.2 km2 the variability in integrated water vapor and liquid water path does approach the retrieved values, while domains with a smaller domains have a larger underestimation of the variability. The simulations indicate a correlation between the degree of organization, Iorg and the precipitation flux, variability in integrated water vapor, and variability in liquid water path. A similar slope of dependency between the variability in integrated water vapor and Iorg is found, across all simulations. In comparison the slopes of dependency between the Iorg and both the variability in liquid water path and precipitation flux values differ between each of the simulations. This suggests that there are different structures in the clouds between simulations and that the Iorg is highly controlled by the water vapor distribution. These studies give confidence that the LES has the ability to capture observed conditions, which is important for simulating future climates. For the investigation into the impact of an elevated moisture layer and the corresponding response of the boundary layer clouds, two sets of simulations were generated on a 25.6 km2 domain using the composite case setup from the HAMP comparison. These two sets of simulations include a control simulation and a set of 5 elevated moisture layer simulations with varying elevated moisture layer depth. While the elevated moisture layer has a significant impact on the atmospheric conditions in the free troposphere, while the largest impact in the boundary layer occurs in the cloud fraction. A decrease in the cloud layer depth is found with increasing elevated moisture layer depth. The impact is not however limited to the vertical structure of the clouds with a significant impact also found in the radiative fluxes throughout the lower troposphere. In order to determine the response of the boundary layer clouds to a change in climate, represented here by the elevated moisture layer, the cloud radiative effect is calculated at the top of the cloud layer. The results indicate there is a positive feedback from the boundary layer clouds produced in response to the elevated moisture layer, which indicates that these clouds have a warming effect on the boundary layer

Forecasting the Spread and Invasive Potential of Apple Snails (Pomacea spp.) in Florida

Forecasting the potential range of invasive species is a critical component for risk assessment, monitoring, and management. However, many of these invasive species are not yet at equilibrium which can be problematic for many modelling approaches. Using the climate matching method, MaxEnt, a series of species distribution models (SDMs) and risk analysis maps were created for select apple snail species in Florida: Pomacea canaliculata, P. diffusa, and P. maculata. Apple snails, freshwater gastropods in the family Ampullariidae, are native to South America and were introduced to the United States via the pet trade approximately 40 years ago. These highly invasive species have already been introduced in ten states and established in at least seven. The models and risk analysis in this study show the majority of Florida was at least moderately suitable for all apple snails modeled, with P. maculata posing the greatest threat

A Strategy for a Global Observing System for Verification of National Greenhouse Gas Emissions

Abstract and PDF report are also available on the MIT Joint Program on the Science and Policy of Global Change website (http://globalchange.mit.edu/).With the risks of climate change becoming increasingly evident, there is growing discussion regarding international treaties and national regulations to lower greenhouse gas (GHG) emissions. Enforcement of such agreements is likely to depend formally upon national and sectoral emission reporting procedures (sometimes referred to as “bottom-up” methods). However, for these procedures to be credible and effective, it is essential that these reports or claims be independently verified. In particular, any disagreements between these “bottom-up” emission estimates, and independent emission estimates inferred from global GHG measurements (so-called “top-down” methods) need to be resolved. Because emissions control legislation is national or regional in nature, not global, it is also essential that “top-down” emission estimates be determined at these same geographic scales. This report lays out a strategy for quantifying and reducing uncertainties in greenhouse gas emissions, based on a comprehensive synthesis of global observations of various types with models of the global cycles of carbon dioxide and other greenhouse gases that include both the natural and human influences on these cycles. The overall goal is to establish a global observing and estimation system that incorporates all relevant available knowledge (physical, biogeochemical, technological and economic) in order to verify greenhouse gas emissions, as a key component of any global GHG treaty.Lockheed Martin Corporation and the MIT Joint Program on the Science and Policy of Global Change, which is funded by a consortium of government, industry and foundation sponsors

Associations among Race/Ethnicity, ApoC-III Genotypes, and Lipids in HIV-1-Infected Individuals on Antiretroviral Therapy

BACKGROUND: Protease inhibitors (PIs) are associated with hypertriglyceridemia and atherogenic dyslipidemia. Identifying HIV-1-infected individuals who are at increased risk of PI-related dyslipidemia will facilitate therapeutic choices that maintain viral suppression while reducing risk of atherosclerotic diseases. Apolipoprotein C-III (apoC-III) gene variants, which vary by race/ethnicity, have been associated with a lipid profile that resembles PI-induced dyslipidemia. However, the association of race/ethnicity, or candidate gene effects across race/ethnicity, with plasma lipid levels in HIV-1-infected individuals, has not been reported. METHODS AND FINDINGS: A cross-sectional analysis of race/ethnicity, apoC-III/apoA-I genotypes, and PI exposure on plasma lipids was performed in AIDS Clinical Trial Group studies (n = 626). Race/ethnicity was a highly significant predictor of plasma lipids in fully adjusted models. Furthermore, in stratified analyses, the effect of PI exposure appeared to differ across race/ethnicity. Black/non-Hispanic, compared with White/non-Hispanics and Hispanics, had lower plasma triglyceride (TG) levels overall, but the greatest increase in TG levels when exposed to PIs. In Hispanics, current PI antiretroviral therapy (ART) exposure was associated with a significantly smaller increase in TGs among patients with variant alleles at apoC-III-482, −455, and Intron 1, or at a composite apoC-III genotype, compared with patients with the wild-type genotypes. CONCLUSIONS: In the first pharmacogenetic study of its kind in HIV-1 disease, we found race/ethnic-specific differences in plasma lipid levels on ART, as well as differences in the influence of the apoC-III gene on the development of PI-related hypertriglyceridemia. Given the multi-ethnic distribution of HIV-1 infection, our findings underscore the need for future studies of metabolic and cardiovascular complications of ART that specifically account for racial/ethnic heterogeneity, particularly when assessing candidate gene effects

Global impact of unproductive splicing on human gene expression

Alternative splicing (AS) in human genes is widely viewed as a mechanism for enhancing proteomic diversity. AS can also impact gene expression levels without increasing protein diversity by producing ‘unproductive’ transcripts that are targeted for rapid degradation by nonsense-mediated decay (NMD). However, the relative importance of this regulatory mechanism remains underexplored. To better understand the impact of AS–NMD relative to other regulatory mechanisms, we analyzed population-scale genomic data across eight molecular assays, covering various stages from transcription to cytoplasmic decay. We report threefold more unproductive splicing compared with prior estimates using steady-state RNA. This unproductive splicing compounds across multi-intronic genes, resulting in 15% of transcript molecules from protein-coding genes being unproductive. Leveraging genetic variation across cell lines, we find that GWAS trait-associated loci explained by AS are as often associated with NMD-induced expression level differences as with differences in protein isoform usage. Our findings suggest that much of the impact of AS is mediated by NMD-induced changes in gene expression rather than diversification of the proteome

The Grizzly, November 10, 1998

Financial Aid: Who Here Gets It? • President Pleased with Success of Roundtable • Upperclassman Mentors • Opinion: Letter to the Editor; New Athletic Facility; Reflection on Mid-term Elections; U.S. Policy Makers, Look Before you Leap; Cashing in on the Past • Betting, Off-Track and On-Campus • Kidnapped? Grizzly Uncovers Surprising Truth About Missing Corson Statue • War Years Classes Dedicate Promise-Anthem • Remembering War Years Life at Ursinus • Eden Cinema at Ursinus • Waiting for the World to Catch Up • Swimming Takes First Plunge • UC Field Hockey Finishes Strong • Bears\u27 Future: Contenders or Pretenders? • NCAA Sets to Control Wrestling Tragedies • Men\u27s Basketball Prepares for Tough Schedule • Ursinus Athletes Honored • UC Soccer Finishes Season with Tough Losshttps://digitalcommons.ursinus.edu/grizzlynews/1428/thumbnail.jp

The Grizzly, December 8, 1998

Actual Implications of Student Evaluations • Students Debate Greek Life on Campus • Opinion: Letter to the Editor; Greek Life Controversy; Who\u27s Recycling? • Final Exam Schedule • Baseball Coach Discusses Return to Vietnam • New Law Helps College Students Manage Debt • WVOU Benefit a Success • High-Tech Cheating, For a Price • Panelists Square Off on Global Warming • Women\u27s Basketball Setting Their Mark • Men\u27s Basketball Opens League Play With Win • UC Swimming in Full Swinghttps://digitalcommons.ursinus.edu/grizzlynews/1430/thumbnail.jp