Oceanography and Atmospheric Sciences and Meteorology Commons^™

The Impact Of Eddies On Nutrient Supply, Diatom Biomass And Carbon Export In The Northern South China Sea, Yung-Yen Shih, Chin-Chang Hung, Sing-How Tuo, Huan-Jie Shao, Chun Hoe Chow, Francois L.L. Muller, Yuan-Hong Cai

OES Faculty Publications

We have investigated the effect of eddies (cold and warm eddies, CEs and WEs) on the nutrient supply to the euphotic zone and the organic carbon export from the euphotic zone to deeper parts of the water column in the northern South China Sea. Besides basic hydrographic and biogeochemical parameters, the flux of particulate organic carbon (POC), a critical index of the strength of the oceanic biological pump, was also measured at several locations within two CEs and one WE using floating sediment traps deployed below the euphotic zone. The POC flux associated with the CEs (85 ± 55 mg-C …

Governance Of Arctic Shipping: Rethinking Risks, Human Impacts And Regulation, Aldo Chircop, Floris Goerlandt, Claudio Aporta, Ronald Pelot

OER Texts

This open access book is a result of the Dalhousie-led research project Safe Navigation and Environment Protection, supported by a grant from the Ocean Frontier Institute’s the Canada First Research Excellent Fund (CFREF). The book focuses on Arctic shipping and investigates how ocean change and anthropogenic impacts affect our understanding of risk, policy, management and regulation for safe navigation, environment protection, conflict management between ocean uses, and protection of Indigenous peoples’ interests. A rapidly changing Arctic as a result of climate change and ice loss is rendering the North more accessible, providing new opportunities while producing impacts on the Arctic. …

Classifying Tornadic Storms In The Tennessee Valley, Clara Hochmuth

Summer Community of Scholars Posters (RCEU and HCR Combined Programs)

No abstract provided.

Near-Bottom Currents At Station M In The Northeast Pacific, Thomas Connolly, Paul Mcgill, Richard Henthorn, Drew Burrier, Cynthia Michaud

Faculty Research, Scholarly, and Creative Activity

No abstract provided.

Factors Influencing Rainfall Over The Congo, Ajay Raghavendra

Legacy Theses & Dissertations (2009 - 2024)

The hydrological cycle over tropical rainforests includes some of the most intense thunderstorms and rainfall totals. The energy associated with this convective activity plays an important role in the Earth’s weather and climate system. Therefore, the interannual variability, trends, and future climate projections of the hydrological cycle over tropical rainforests are important topics for research. The Congo rainforest situated over equatorial Africa is the second largest rainforest in the world, and recent studies have documented a >30-year large-scale and long-term drying trend over the Congo since the late-1970s. However, unlike the Amazon rainforest in South America, the Congo rainforest is …

The Impact Of Warm Conveyor Belt Forecast Uncertainty On Downstream Predictability, Jeremy Berman

Legacy Theses & Dissertations (2009 - 2024)

Perturbations to the potential vorticity (PV) waveguide can lead to the downstream radiation of Rossby waves, and in turn high-impact weather events. The PV waveguide is often perturbed in association with cyclogenesis, largely due to the latent heat release within the cyclone’s warm conveyor belt (WCB). Previous studies have hypothesized that forecast uncertainty associated with diabatic heating in WCBs can result in large downstream forecast variability; however these studies have not established a direct connection between the two. This hypothesis is evaluated for six cyclogenesis events characterized by highly amplified flow over the North Atlantic using ensemble model simulations.

Ozone And Reactive Oxidized Nitrogen Chemistry In The Northeast U.S, Matthew Ninneman

Legacy Theses & Dissertations (2009 - 2024)

Ongoing reductions in oxides of nitrogen concentrations ([NOx] = nitric oxide ([NO]) + nitrogen dioxide ([NO2])) throughout the continental United States (U.S.) have important implications for tropospheric ozone (O3) and reactive oxidized nitrogen chemistry (NOy ≈ NOx + nitric acid (HNO3) + particle nitrate (pNO3) + peroxy nitrates (PNs) + alkyl nitrates (ANs)). Specifically, decreasing [NOx] concentrations have likely (1) increased the sensitivity of O3 to the [NOx] level, and (2) affected NOy speciation and partitioning. An understanding of the impacts of continued [NOx] reductions is needed to inform current and future air pollution control strategies, especially since the National …

Global Circulation Variability Associated With Mjo Phase Speed, Alexander Marat Tomoff

Legacy Theses & Dissertations (2009 - 2024)

Differences in the Madden–Julian oscillation (MJO) phase speed help explain some of the variability in the global circulation patterns associated with the MJO. Select mechanisms that identify these distinctive circulation signals are applied to help explain MJO variability associated with different phase speeds. Wavelet filter analysis is first used to compute regression models of the MJO at different phase speeds, isolating the associated patterns in outgoing longwave radiation (OLR), geopotential height, and upper-level wind. Covariance matrices provide a deeper understanding of how the tropical and extratropical patterns compare between two phase speeds at any point in time. Both Fourier and …

An Analysis Of Temperature Trends In The Northeast United States : 1950-2019, Christopher Selca

Legacy Theses & Dissertations (2009 - 2024)

The warming signal associated with anthropogenic climate change shows a significant positive trend globally over the last century. Trends in the magnitude and frequency of annual mean and extreme events do not display a globally uniform signal, as some regions have shown negative trends. This study examines the trends in daily mean and extreme temperatures in the Northeast region of the United States. Station data was selected from the GHCN-D Version 3 data set, using a blend of stations from the weather forecast offices and the cooperative observing network. Station criteria included using a threshold of less than 5% of …

Examining The Impact Of Synoptic-Scale Waves On Stratospheric Polar Vortex Variability From An Ensemble Forecast Perspective, Michael E. Main

Legacy Theses & Dissertations (2009 - 2024)

Major Sudden Stratospheric Warming (SSW) events are characterized by rapid warming of the polar regions at 10 hPa and are accompanied by a reversal of the 10-hPa zonal-mean zonal wind at 60˚N from westerly to easterly. Following an SSW event, stratospheric thermal and momentum anomalies can progress downward and linger near the tropopause for up to 60 days. These anomalies have major impacts on tropospheric sensible weather including increased likelihood of cold air outbreaks and heavy precipitation events. SSW events are largely forced by upward propagation of planetary-scale Rossby waves from the troposphere to the stratosphere. Synoptic-scale waves can contribute …

Dynamical Downscaling Of Near-Term Climate Variability And Change For The Main Hawaiian Islands Using Wrf, Katrina Marie Fandrich

Legacy Theses & Dissertations (2009 - 2024)

As climate models continue to improve, the demand from resource managers and decision-makers for more accurate climate projections is increasing. However, natural climate variability poses a limit to the confidence in regional climate change projections, particularly for the mid-21st century. The unique geographic location of the Hawaiian Islands and its regional climate provide a challenging opportunity for climate modelers. The goal of this project is to examine both the Pacific Decadal Oscillation (PDO) and anthropogenic climate change for their impacts on near-term rainfall and temperature projections for the Hawaiian Islands. Of primary interest are the questions 1) is there a …

Improving Our Understanding Of The Relationship Between Ocean Heat Uptake And Climate Sensitivity, Michael Cameron Rencurrel

Legacy Theses & Dissertations (2009 - 2024)

One of the ultimate goals of the field of climate science is to determine exactly how sensitive the Earth is to anthropogenic forcing, with far reaching implications both from a scientific and policy standpoint. However, despite decades of observational and model analysis, large uncertainties in Earth's climate sensitivity persist. Recent advances have shown that climate feedbacks, the primary mechanism driving the sensitivity spread, are dependent on the spatial patterns of the surface response, intrinsically linked to how the ocean is working to uptake and transport energy across the globe. Given the importance of reducing the range of climate sensitivity from …

Easterly Waves Over The Eastern Pacific, Victor Manuel Torres Puente

Legacy Theses & Dissertations (2009 - 2024)

The research in this thesis explores different processes associated with the life cycle of Easterly Waves over the tropical Eastern Pacific. These include genesis, structural evolution, intensification and a dissipating stage.

Evaluating Large-Scale And Storm-Scale Characteristics Of Rapidly Intensifying And Slowly Intensifying Tropical Cyclones Using An Analog Approach, Jannetta C. Richardson

Legacy Theses & Dissertations (2009 - 2024)

Tropical cyclone (TC) intensity change is modulated by a combination of large-scale and storm-scale processes. On the large-scale, several factors exhibit strong controls on TC rapid intensification (RI): the initial TC intensity, the environmental vertical wind shear (VWS), and the background thermodynamic environment, which determines the TC’s maximum potential intensity (MPI). Previous statistical studies comparing RI and non-RI TCs have shown that TCs undergoing RI tend to be embedded in environments of lower VWS, and have initial intensities that are farther from their MPIs. Although numerous statistical studies have compared the large-scale and storm-scale conditions of RI and non-RI TCs, …

The Significance Of The Nontraditional Coriolis Terms In Tropical Large-Scale Dynamics, Heng Wang

Legacy Theses & Dissertations (2009 - 2024)

The nontraditional Coriolis terms (NCTs) turn eastward motion upward and upward motion westward, and vice versa. NCTs are omitted in most of the current global atmospheric models. However, NCTs are significant in tropical large-scale dynamics in at least three aspects. 1) Using an idealized model that can switch NCTs on or off, omitting NCTs biases large-scale flow response to prescribed diabatic forcing mimicking the intertropical convergence zone (ITCZ). The omission yields a westerly wind bias in the heating region ~ 10% of the westerly jet stream. This bias is due to lack of westward NCT when heating-induced upward motion is …

Estimating Abiotic Thresholds For Sagebrush Condition Class In The Western United States, Stephen Boyte, Bruce K. Wylie, Yingxin Gu, Donald J. Major

United States Geological Survey: Staff Publications

Sagebrush ecosystems of the western United States can transition from extended periods of relatively stable conditions to rapid ecological change if acute disturbances occur. Areas dominated by native sagebrush can transition from species-rich native systems to altered states where non-native annual grasses dominate, if resistance to annual grasses is low. The non-native annual grasses provide relatively little value to wildlife, livestock, and humans and function as fuel that increases fire frequency. The more land area covered by annual grasses, the higher the potential for fire, thus reducing the potential for native vegetation to reestablish, even when applying restoration treatments. Mapping …

Applied Injected Air Into Subsurface Drip Irrigation: Plant Uptake Of Pharmaceuticals And Soil Microbial Communities, Matteo D'Alessio, Lisa M. Durso, Clinton Williams, Christopher A. Olson, Chittaranjan Ray, Ellen Paparozzi

Nebraska Water Center: Faculty Publications

The growing global food security crisis is complicated by the need for increased crop production with less arable land and limited water resources. Reuse of treated wastewater for agricultural irrigation is becoming more common, often paired with other conservation measures such as subsurface drip irrigation (SDI). Passively injecting air into SDI systems increases crop yields and overcomes root zone wetting issues. However, when used with treated irrigation water, contaminants in the water might be taken up by the crops. This paper investigates the impact of air-injected water containing caffeine, carbamazepine, and gemfibrozil on plant uptake and soil microbial communities in …

Droughtscape, Winter 2019, Cory Matteson

DroughtScape: Quarterly Newsletter of the National Drought Mitigation Center (2007–2023)

Contents

From the Director

4th quarter climate summary

2019 year in review summary

4th quarter drought impact summary

2019 drought impact summary

New form helps ‘see more’ drought

Landscape photographers invited to submit photos

Helping Central and South America planning

Database includes more drought planning

Assessing If Motivation Impacts General Aviation Pilots’ Persistence In Varying Weather Conditions, Sabrina Woods

Doctoral Dissertations and Master's Theses

Continued flight under visual flight rules into instrument meteorological conditions is the predominant cause for fatal accidents by percentage, for general aviation aircraft operations. It is possible that a pilot’s motivation or reason for flying will override other safer, more logical courses of action when a hazard presents itself. The decision appears to stem from a willingness to persist in a course of action despite factors that indicate an alternate and safer course is warranted. This research addresses what is currently presumed about the decision to continue flying under visual flight rules into instrument conditions and marries those ideas with …

Development Of An Infrared Pollution Index To Identify Ground-Level Compositional, Particle Size, And Humidity Changes Using Himawari-8, M. Sowden, D. Blake, D. Cohen, A. Atanacio, Ute Mueller

Research outputs 2014 to 2021

Speciated air quality data informs health studies and quantitates impacts. However, monitoring is concentrated around populated regions whilst, large remote and rural regions remain unmonitored despite risks of dust-storms or wild-fires. Sub-hourly, infrared, geostationary data, such as the 10-min data from Himawari 8, could potentially be used to quantify regional air quality continually. Monitoring of Aerosol Optical Depth (AOD) is restricted to visible spectra (i.e. daytime only), while newer quantification methods using geostationary infrared (IR) data have focused on detecting the presence, or absence, of an event. Limited attention has been given to the determination of particle size and aerosol …

Multiple Impact Pathways Of The 2015–2016 El Niño In Coastal Kenya, Matt Fortnam, Molly Atkins, Katrina Brown, Tomas Chaigneau, Ankje Frouws, Kemyline Gwaro, Mark Huxham, James Kairo, Amon Kimeli, Bernard Kirui, Katy Sheen

Research outputs 2014 to 2021

© 2020, The Author(s). The 2015–2016 El Niño had large impacts globally. The effects were not as great as anticipated in Kenya, however, leading some commentators to call it a ‘non-event’. Our study uses a novel combination of participatory Climate Vulnerability and Capacity Analysis tools, and new and existing social and biophysical data, to analyse vulnerability to, and the multidimensional impacts of, the 2015–2016 El Niño episode in southern coastal Kenya. Using a social-ecological systems lens and a unique dataset, our study reveals impacts overlooked by conventional analysis. We show how El Niño stressors interact with and amplify existing vulnerabilities …

Modeling Iron And Light Controls On The Summer Phaeocystis Antarctica Bloom In The Amundsen Sea Polynya, Hilde Oliver, Pierre St-Laurent, Robert M. Sherrell, Patricia L. Yaeger

CCPO Publications

Of all the Antarctic coastal polynyas, the Amundsen Sea Polynya is the most productive per unit area. Observations from the 2010-2011 Amundsen Sea Polynya International Research Expedition (ASPIRE) revealed that both light and iron can limit the growth of phytoplankton (Phaeocystis antarctica), but how these controls manifest over the bloom season is poorly understood, especially with respect to their climate sensitivity. Using a 1-D biogeochemical model, we examine the influence of light and iron limitation on the phytoplankton bloom and vertical carbon flux at 12 stations representing different bloom stages within the polynya. Model parameters are determined by …

Vertical Processes And Resolution Impact Ice Shelf Basal Melting: A Multi-Model Study, David E. Gwyther, Kazuya Kusahara, Xylar S. Asay-Davis, Michael S. Dinniman, Benjamin K. Galton-Fenzi

CCPO Publications

Understanding ice shelf–ocean interaction is fundamental to projecting the Antarctic ice sheet response to a warming climate. Numerical ice shelf–ocean models are a powerful tool for simulating this interaction, yet are limited by inherent model weaknesses and scarce observations, leading to parameterisations that are unverified and unvalidated below ice shelves. We explore how different models simulate ice shelf–ocean interaction using the 2nd Ice Shelf–Ocean Model Intercomparison Project (ISOMIP+) framework. Vertical discretisation and resolution of the ocean model are shown to have a significant effect on ice shelf basal melt rate, through differences in the distribution of meltwater fluxes and the …

Global Sea Level Reconstruction For 1900-2015 Reveals Regional Variability In Ocean Dynamics And An Unprecedented Long Weakening In The Gulf Stream Flow Since The 1990s, Tal Ezer, Sönke Dangendorf

CCPO Publications

A new monthly global sea level reconstruction for 1900-2015 was analyzed and compared with various observations to examine regional variability and trends in the ocean dynamics of the western North Atlantic Ocean and the U.S. East Coast. A proxy of the Gulf Stream (GS) strength in the Mid-Atlantic Bight (GS-MAB) and in the South Atlantic Bight (GS-SAB) were derived from sea level differences across the GS in the two regions. While decadal oscillations dominate the 116-year record, the analysis showed an unprecedented long period of weakening in the GS flow since the late 1990s. The only other period of long …

Mean Sea Level Changes In The Southwestern Baltic Sea Over The Last 190 Years, Jessica Kelln, Sönke Dangendorf, Ulf Gräwe, Holger Steffen, Justus Patzke, Jürgen Jensen

CCPO Publications

(First paragraph) Over the 20th century a global mean sea level (GMSL) rise of about 1.3 to 2 mm/yr could be observed and it is projected to further accelerate throughout the 21st century (Church and White 2006, Hay et al., 2015; Dangendorf et al., 2017). However, GMSL rise is neither temporally nor spatially uniform. Because of a number of different factors (e.g. mass changes and gravitational effects due to melting ice sheets/glaciers, expanding/contracting volume due to temperature and salinity fluctuations, ocean circulation changes, atmospheric forcing), regional mean sea level (MSL) trends can vary significantly from the global average. In order …

Analysis Of Iron Sources In Antarctic Continental Shelf Waters, Michael S. Dinniman, Pierre St-Laurent, Kevin R. Arrigo, Eileen E. Hofmann, Gert L. Van Dijken

CCPO Publications

Previous studies showed that satellite‐derived estimates of chlorophyll a in coastal polynyas over the Antarctic continental shelf are correlated with the basal melt rate of adjacent ice shelves. A 5‐km resolution ocean/sea ice/ice shelf model of the Southern Ocean is used to examine mechanisms that supply the limiting micronutrient iron to Antarctic continental shelf surface waters. Four sources of dissolved iron are simulated with independent tracers, assumptions about the source iron concentration for each tracer, and an idealized summer biological uptake. Iron from ice shelf melt provides about 6% of the total dissolved iron in surface waters. The contribution from …

The “Challenge" Of Depletion: Why The Oyster Fishery Is Not Self-Regulating, Eric N. Powell, John M. Klinck, Leanne M. Poussard

CCPO Publications

The possibility that the economics of the oyster fishery impose a self-limitation on overharvesting has been proffered on occasion. The inefficiency of harvesting by the fishery has been evaluated and estimates of the exploitation rate permissible under conditions of maximum sustainable yield have been obtained in previous studies. The question becomes to what extent does the inefficiency of harvest interact with the economics of the fishery to compromise ready detection of overfishing? This study explores the possibility that the constraint of economics on the fishery occurs at oyster exploitation rates that are higher than maximum sustainable yield, leading ineluctably to …

20th Century Multivariate Indian Ocean Regional Sea Level Reconstruction, Praveen Kumar, Benjamin Hamlington, Se-Hyeon Cheon, Weiqing Han, Phillip Thompson

CCPO Publications

Despite having some of the world's most densely populated and vulnerable coastlines, Indian Ocean sea level variability over the past century is poorly understood relative to other ocean basins primarily, due to the short and sparse observational records. In an attempt to overcome the limitations imposed by the lack of adequate observations, we have produced a 20th century Indian Ocean sea level reconstruction product using a new multivariate reconstruction technique. This technique uses sea level pressure and sea surface temperature in addition to sea level data to help constrain basin‐wide sea level variability by (1) the removal of large spurious …

Constraining An Ocean Model Under Getz Ice Shelf, Antarctica, Using A Gravity‐Derived Bathymetry, Romain Millan, Pierre St-Laurent, Eric Rignot, Mathieu Morlighem, Jeremie Mouginot, Bernd Scheuchl

CCPO Publications

Getz Ice Shelf, the largest producer of ice shelf meltwater in Antarctica, buttresses glaciers that hold enough ice to raise sea level by 22 cm. We present a new bathymetry of its sub‐ice shelf cavity using a three‐dimensional inversion of airborne gravity data constrained by multibeam bathymetry at sea and a reconstruction of the bedrock from mass conservation on land. The new bathymetry is deeper than previously estimated with differences exceeding 500 m in a number of regions. When incorporated into an ocean model, it yields a better description of the spatial distribution of ice shelf melt, specifically along glacier …

Phenology Of Cupressaceae Urban Infrastructure Related To Its Pollen Content And Meteorological Variables, A. Monroy-Colín, J. M. Maya-Manzano, I. Silva-Palacios, R. Tormo-Molina, R. Pecero-Casimiro, Á. Gonzalo-Garijo, S. Fernández-Rodríguez

Articles

Cupressaceae pollen is one of the major airborne allergens of the Mediterranean region and in other regions around the world. Pollen production of these species causes considerable allergic problems during winter, being this type of pollen the most abundant in this period of the year. This work aims to relate phenology, meteorology and airborne pollen records in these species. Aerobiological sampling was carried out in Badajoz (SW Spain) from 2016 to 2018 using Hirst-type volumetric sampler. Pollination phenology was studied in 50 specimens, ten of Cupressus macrocarpa, ten of Cupressus arizonica, 15 of Cupressus sempervirens and 15 of …