Atmospheric Sciences Commons^™

Gaseous Pollutants Emission From Diesel Vehicles In Hong Kong, Bei, Helen Wang, Yik Sze Lau, Kin Fai Ho

Faculty of Science & Technology (THEi)

The current study presents the detailed investigation of diesel vehicles emissions utilizing chassis dynamometer test in Hong Kong. Gaseous pollutants from diesel vehicle exhaust, including nitrogen oxides (NO_x), total hydrocarbon (THC) and carbon monoxide (CO), are chosen to be the targets of this study. These pollutants were monitored real-time during different testing cycles and the data collected were used to calculate the fuel-based emission factor of each pollutant. Results showed that emission standard and driving conditions are the two main factors governing the trend of emission of these pollutants. Outliers observed in these trends are probably caused by …

Drought And Land-Cover Conditions In The Great Plains, Heather Tollerud, Jesslyn Brown, Thomas Loveland, Rezaul Mahmood, Norman Bliss

High Plains Regional Climate Center: Staff Publications

Land–atmosphere interactions play a critical role in the Earth system, and a better understanding of these interactions could improve weather and climate models. The interaction among drought, vegetation productivity, and land cover is of particular significance. In a semiarid environment, such as the U.S. Great Plains, droughts can have a large influence on the productivity of agriculture and grasslands, with serious environmental and economic impacts. Here, we used the vegetation drought response index (VegDRI) drought indicator to investigate the response of vegetation to weather and climate for landcover types in the Great Plains in the United States from 1989 to …

Droughtscape, Winter 2018, National Drought Mitigation Center

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

Contents

Year in review: Drought eased in California, developed in Northern Plains

Quarterly Summary: Drought creeps across the country

Annual impact summary: A year of wildfires

Quarterly impact summary: Drought expands in Texas, Colorado

Drought and water crisis book updated

U.S. Drought Monitor available in Spanish

Study shows cities step up when drought occurs

New staff at the NDMC

Drought Summit in photos

Climate Modeling, Outgoing Longwave Radiation, And Tropical Cyclone Forecasting, Thomas Rechtman

Honors Undergraduate Theses

Climate modeling and tropical cyclone forecasting are two significant is- sues that are continuously being improved upon for more accurate weather forecasting and preparedness. In this thesis, we have studied three climate models and formulated a new model with a view to determine the outgoing longwave radiation (OLR) budget at the top of the atmosphere (TOA) as ob- served by the National Oceanic and Atmospheric Administration’s (NOAA) satellite based Advanced Very High Resolution Radiometer (AVHRR). In 2006, Karnauskas proposed the African meridional OLR as an Atlantic hur- ricane predictor, the relation was further proven in 2016 by Karnauskas and Li …

Surface Air Temperature Biases And Other Associated Biases In Gfdl Am4.0 Model, Yilin Lu

Legacy Theses & Dissertations (2009 - 2024)

The Atmospheric Model version 4.0 (AM4) is the atmospheric component of the latest climate and Earth system models (CM4 and ESM4) developed by NOAA’s Geophysical Fluid Dynamics Laboratory (GFDL) in Princeton, New Jersey. The AM4 makes some improvements in its radiative flux simulations. As a new model, its performance needs to be evaluated. We analyzed the model’s historical simulations (ten-year simulations from 2001 to 2010), in order to evaluate the diurnal cycle of surface air temperature (Tas) simulated by the AM4 model and perform some diagnostic analyses of the surface energy fluxes to help understand the temperature biases. In comparison …

Changes In Extreme Precipitation In The Northeast United States : 1979-2014, Macy Howarth

Legacy Theses & Dissertations (2009 - 2024)

Extreme precipitation can have significant adverse impacts on infrastructure and property, human health, and local economies. This thesis examines recent changes in extreme precipitation in the Northeast United States, which here includes the states of Maine, New Hampshire, Vermont, New York, Massachusetts, Connecticut, Rhode Island, Pennsylvania, and New Jersey. Daily station data from 58 stations missing less than 5% of days for the years 1979–2014 from the United States Historical Climatology Network was used to analyze both total and extreme precipitation, with the latter defined as the top 1% of days with precipitation.

Aerosol Direct Radiative And Cloud Adjustment Effects On Surface Climate Over The Eastern China : Analyses Of Wrf Model Simulations, Yangyang Song

Legacy Theses & Dissertations (2009 - 2024)

Aerosol climate effects consist of the initial forcing of atmospheric radiation perturbation through both the direct radiative effect and the modulation of radiatively-important cloud microphysics, and the subsequent changes in meteorology that also affect cloud macro- and micro-physics. The aerosol-induced cloud adjustment therefore involves many couplings and interactions, and its quantitative evaluation requires the use of model simulations. This study uses WRF model simulated changes in clouds and meteorology due to anthropogenic aerosol increases (versus 1970s) for 2002−2008 summers over the eastern China to address two relevant issues: direct radiative vs. cloud adjustment effects, and their roles in affecting surface …

Climate Change On The Quelccaya Ice Cap, Central Andes, And Its Relationship With The Large-Scale Circulation, Christian Pedro Yarleque Galvez

Legacy Theses & Dissertations (2009 - 2024)

Glaciated areas over the central Andes are highly sensitive to atmospheric forcings, as demonstrated by their current accelerated retreat in response to global warming. The present Thesis is focused on quantifying and assessing future climate change impacts over Quelccaya ice cap (QIC), the world-largest tropical ice body, which is considered as a representative case of the tropical Andean cryosphere. I focused my study on characterizing large-scale forcing and future changes of precipitation and temperature, since they represent the most important variables for accumulation and ablation processes in glaciated mountain regions. In my research I developed tools to overcome the lack …

On The Role Of Western North Pacific Tropical Cyclones In Shaping The Extratropical Circulation Response To The Madden-Julian Oscillation, Lawrence Christian Gloeckler

Legacy Theses & Dissertations (2009 - 2024)

Relationships between the Madden–Julian oscillation (MJO) and the extratropical circulation have been leveraged extensively to improve subseasonal prediction. However, in certain situations, tropical cyclones (TCs), which often coincide with enhanced MJO activity, can constructively or destructively interfere with MJO organization and common pathways through which the extratropics responds to the MJO. To examine this potential interference, the first portion of this study leverages a statistical experiment to relate West Pacific TC presence in different parts of the basin during a given MJO phase to subsequent remote extratropical circulation outcomes. The results of this experiment demonstrate that significant, high amplitude remote …

Extratropical Cyclones Leading To Extreme Weather Events Over Central And Eastern North America, Alicia Marie Bentley

Legacy Theses & Dissertations (2009 - 2024)

Cool-season extreme weather events (EWEs) occurring over central and eastern North America are typically associated with strong extratropical cyclones (ECs) that are governed by varying combinations of baroclinic, diabatic, and barotropic processes. This dissertation investigates the climatology, evolution, and predictability of ECs leading to EWEs over central and eastern North America, and provides a foundation on which to compare ECs leading to EWEs to ordinary ECs forming over and traversing the same regions.

Stratospheric And Tropospheric Contributions To The Poleward Energy Flux Across 70°N And 65°S In The Merra-2 And Cesm, Christopher Cardinale

Legacy Theses & Dissertations (2009 - 2024)

The flux of moist static energy (MSE) across 70°N and 65°S plays a key role in the energy budget and climate of the polar regions. This flux, which provides respectively 98 W m⁻² and 91 W m⁻² heating of the northern and southern polar caps, is usually studied from a vertically integrated perspective. Its vertical structure is examined using the NASA-MERRA-2 reanalysis to compute monthly fluxes of sensible, latent and potential energy across 70°N and 65°S for the period 1980-2016. The flux is bimodal, with peaks in the lower troposphere and in the middle stratosphere, and is near zero at …

Understanding The Relationship Between Winter Hawaii Precipitation And North Pacific Climate Variability For Past And Present Climate Conditions, Siyu Li

Legacy Theses & Dissertations (2009 - 2024)

Kona lows (KLs) are a type of seasonal cut-off cyclones in the North Pacific around the Hawaiian Islands during the cold season month (Oct.-Apr.). KLs are important for the annual rainfall budget of the Hawaiian Islands. This study investigates what controls the winter precipitation variability over the Hawaiian Islands in the present-day climate and within a long-term paleoclimate simulation. ERA-interim data from 1979-2014 are used for the present-day analysis of the large-scale circulation. The potential vorticity is used as a measure of extratropical synoptic activity. The Hawaii Rainfall Index is from the Rainfall Atlas of Hawaii (seasonal means, 1920-2012). For …

Influence Of Lightning-Producing Convection On Tropical Cyclone Intensity Change, Stephanie Stevenson

Legacy Theses & Dissertations (2009 - 2024)

Lightning observations in tropical cyclones (TCs) over the ocean are a recent advance- ment, and while many studies have noted relationships between lightning and TC intensity change, the relationships are not consistent. This dissertation aims to understand the com- plexities of the relationships between lightning and TC intensity change, and associate the relationships to storm kinematic, thermodynamic, and microphysical processes.

Dry Air, Midlevel Flow, And The Persistence Of Deep Convection In Atlantic Tropical Disturbances, Charles Helms

Legacy Theses & Dissertations (2009 - 2024)

An analysis of dropsonde-observed relative humidity in the Tropical Storm Gabrielle (2013) pregenesis disturbance suggests the presence of a layer of dry air that is being advected into the disturbance from the north. The focus of this study is on this and similar dry air layers, termed dry air inflow pathways (DAIPs), that are characterized by unidirectional disturbance-relative flow drawing dry air into a tropical disturbance. It is hypothesized that DAIPs act to prevent the establishment of persistent deep convection by importing midlevel

The Relationship Between Tropospheric Synoptic-Scale Events, Vertical Wave Activity Flux, And Sudden Stratospheric Warmings In The Boreal Winter, Hannah Elizabeth Attard

Legacy Theses & Dissertations (2009 - 2024)

Rapid breakdowns of the climatological mid-winter stratospheric polar vortex [i.e., sudden stratospheric warmings (SSWs)] are often preceded by tropospheric blocks. While some studies suggest that blocks can induce the upward wave activity flux (WAF) through the tropopause region that is necessary to trigger an SSW, other studies show no statistical relationship between tropospheric blocks and SSWs. One objective of this dissertation is to elucidate the dynamical relationship between tropospheric blocks and SSWs by exploring the relationship between blocks and tropopause-level upward WAF. Along with analyzing blocks, this dissertation also explores rapidly deepening extratropical cyclones (i.e., bombs) and tropical cyclones that …

Understanding Large Wind Farm Impacts On Regional Climate And Vegetation Growth From Observational And Modeling Perspectives, Geng Xia

Legacy Theses & Dissertations (2009 - 2024)

In the most recent decade, wind energy has experienced exponential growth worldwide and this rapid increase is expected to continue, particularly over farmlands in the United States. This poses an important question regarding whether the widespread deployment of wind turbines (WTs) will influence surface/near-surface microclimate and vegetation growth. In this dissertation, I investigate the potential wind farm (WF) impacts on regional climate and vegetation growth from both observational and modeling perspectives. High resolution satellite, radiosonde and field observations are used to determine the magnitude and variability of WF-induced changes on surface/near-surface temperatures while the Weather Research and Forecasting (WRF) model …

Field Evaluation Of Portable Air Quality Monitors And Evaluation Of Short-Lived Plume Events Of Atmospheric Pollutants, Joseph Peter Marto

Legacy Theses & Dissertations (2009 - 2024)

Availability of low cost optical sensors has allowed for the supplementation of existing air quality infrastructure with portable, adaptive monitors. While these sensors generally cannot offer the same accuracy and precision as established analysis methods, they can still reliably detect changes in pollutant concentration. This study evaluates the performance of two portable air quality enclosures deployed at collocated research sites to determine their accuracy and usefulness in field deployments. One system deployed collocated sensors for measurement of particulate matter mass concentration (Thermo pDR 1500 and TSI DustTrak DRX for PM2.5) and the second system deployed sensors for measurement of black …

Tropical Cyclone Rapid Intensification In Environments Of Upper-Tropospheric Troughs : Environmental Influences And Convective Characteristics, Michael Fischer

Legacy Theses & Dissertations (2009 - 2024)

Intensity forecasts for tropical cyclones that undergo a period of rapid intensification are particularly susceptible to large errors. For those storms that interact with an upper-tropospheric trough, tropical cyclone intensity forecasts are complicated, as upper-tropospheric troughs can provide unique intensification mechanisms, but are often associated with unfavorable environmental conditions. Although tropical cyclones in environments with nearby upper-tropospheric troughs are associated with lesser intensification rates than tropical cyclones in environments devoid of upper-tropospheric troughs, some tropical cyclone--trough interactions are associated with a period of rapid intensification. This dissertation utilizes reanalysis output, satellite observations, and ensemble modeling simulations to understand whether rapid …

Global Response To The Madden-Julian Oscillation As A Function Of Phase Speed In Era-Interim Reanalysis And Miroc5 Model Data, Kaitlyn Krzyzaniak

Legacy Theses & Dissertations (2009 - 2024)

Many authors state that the phase speed of the Madden–Julian oscillation (MJO) is near 5ms–1, but observations suggest it varies considerably. MJO propagation typically sets off Rossby wave trains that interact with and alter this extratropical pattern; however, differences in the MJO phase speed could alter the Rossby wave response, leading to a unique response in the extratropics. An understanding of the mechanisms and extratropical responses to variable MJO phase speeds would provide innovative and invaluable insight for subseasonal forecasting.

The Upper-Level Turbulence, Static Stability And Tropopause Structure Of Tropical Cyclones, Patrick Duran

Legacy Theses & Dissertations (2009 - 2024)

Upper-tropospheric thermodynamic processes can play an important role in tropical cyclone (TC) structure and evolution. Despite its importance, until recently few in-situ observations were available in the upper levels of TCs. Two recent field campaigns -- the National Aeronautics and Space Administration (NASA) Hurricane and Severe Storm Sentinel (HS3) and the Office of Naval Research Tropical Cyclone Intensity (TCI) experiment -- provided a wealth of high-altitude observations within TCs. These observations revealed that the upper-level static stability and tropopause structure of TCs can change dramatically with both space and time.