scholarly journals Contrasting Southern Hemisphere Monsoon Response: MidHolocene Orbital Forcing versus Future Greenhouse Gas–Induced Global Warming

2020 ◽  
Vol 33 (22) ◽  
pp. 9595-9613 ◽  
Author(s):  
Roberta D’Agostino ◽  
Josephine R. Brown ◽  
Aurel Moise ◽  
Hanh Nguyen ◽  
Pedro L. Silva Dias ◽  
...  
Keyword(s):  
Greenhouse Gas ◽  
Southern Hemisphere ◽  
Regional Differences ◽  
Energy Input ◽  
Net Energy ◽  
Local Response ◽  
Dynamic Component ◽  
Monsoonal Precipitation ◽  
Dynamic Components ◽  
Gross Moist Stability

AbstractPast changes of Southern Hemisphere (SH) monsoons are less investigated than their northern counterpart because of relatively scarce paleodata. In addition, projections of SH monsoons are less robust than in the Northern Hemisphere. Here, we use an energetic framework to shed lights on the mechanisms determining SH monsoonal response to external forcing: precession change at the mid-Holocene versus future greenhouse gas increase (RCP8.5). Mechanisms explaining the monsoon response are investigated by decomposing the moisture budget in thermodynamic and dynamic components. SH monsoons weaken and contract in the multimodel mean of midHolocene simulations as a result of decreased net energy input and weakening of the dynamic component. In contrast, SH monsoons strengthen and expand in the RCP8.5 multimodel mean, as a result of increased net energy input and strengthening of the thermodynamic component. However, important regional differences on monsoonal precipitation emerge from the local response of Hadley and Walker circulations. In the midHolocene, the combined effect of Walker–Hadley changes explains the land–ocean precipitation contrast. Conversely, the increased local gross moist stability explains the increased local precipitation and net energy input under circulation weakening in RCP8.5.

scholarly journals Local Energetic Constraints on Walker Circulation Strength

2017 ◽  
Vol 74 (6) ◽  
pp. 1907-1922 ◽  
Author(s):  
Robert C. Wills ◽  
Xavier J. Levine ◽  
Tapio Schneider
Keyword(s):  
Global Warming ◽  
Energy Input ◽  
Climate Models ◽  
Walker Circulation ◽  
Static Stability ◽  
Net Energy ◽  
Open Questions ◽  
Wide Range ◽  
Gross Moist Stability ◽  
The Walker Circulation

Abstract The weakening of tropical overturning circulations is a robust response to global warming in climate models and observations. However, there remain open questions on the causes of this change and the extent to which this weakening affects individual circulation features such as the Walker circulation. The study presents idealized GCM simulations of a Walker circulation forced by prescribed ocean heat flux convergence in a slab ocean, where the longwave opacity of the atmosphere is varied to simulate a wide range of climates. The weakening of the Walker circulation with warming results from an increase in gross moist stability (GMS), a measure of the tropospheric moist static energy (MSE) stratification, which provides an effective static stability for tropical circulations. Baroclinic mode theory is used to determine changes in GMS in terms of the tropical-mean profiles of temperature and MSE. The GMS increases with warming, owing primarily to the rise in tropopause height, decreasing the sensitivity of the Walker circulation to zonally anomalous net energy input. In the absence of large changes in net energy input, this results in a rapid weakening of the Walker circulation with global warming.

scholarly journals Strategies for Energy and Climate Management at the British Columbia Institute of Technology

2021 ◽  
Vol 1 ◽  
Author(s):  
Jennie Moore
Keyword(s):  
British Columbia ◽  
Greenhouse Gas Emissions ◽  
Greenhouse Gas ◽  
Energy Use ◽  
Waste Heat ◽  
Net Energy ◽  
Full Time ◽  
Gas Emissions ◽  
Service Levels ◽  
Institute Of Technology

The British Columbia Institute of Technology (BCIT) is Canada's premier polytechnic. In 2008, BCIT partnered with its local electricity utility to hire a full-time energy manager. The following year, BCIT's School of Construction and the Environment initiated a campus-as-living-lab of sustainability project called Factor Four in the seven buildings it occupies on BCIT's main campus in Burnaby. The purpose was to explore whether a four-fold (75%) reduction in materials and energy use could be achieved without compromising service levels. By 2016, the project achieved a 50% reduction in energy use and associated greenhouse gas emissions. Factor Four attracted over four million dollars in funding, engaged over 250 students from 12 educational programs, and produced over $200,000 savings annually. In 2017, BCIT set an ambitious target to reduce its annual greenhouse gas emissions 33% below 2007 levels by 2023, and 80% by 2050, across all five of its campuses. BCIT’s ultimate goal is to become both greenhouse gas neutral and a net energy producer. By setting ambitious targets and systematically implementing energy efficiency improvements, utilizing waste-heat exchange, fuel switching, and developing on-site renewable energy, BCIT is on track to achieving its energy management and climate change goals.

Effect of Surface Fluxes versus Radiative Heating on Tropical Deep Convection

2015 ◽  
Vol 72 (9) ◽  
pp. 3378-3388 ◽  
Author(s):  
Usama Anber ◽  
Shuguang Wang ◽  
Adam Sobel
Keyword(s):  
Large Scale ◽  
Multiple Equilibria ◽  
Initial Conditions ◽  
Deep Convection ◽  
Surface Fluxes ◽  
Radiative Heating ◽  
Net Energy ◽  
Wide Range ◽  
Tropical Deep Convection ◽  
Gross Moist Stability

Abstract The effects of turbulent surface fluxes and radiative heating on tropical deep convection are compared in a series of idealized cloud-system-resolving simulations with parameterized large-scale dynamics. Two methods of parameterizing the large-scale dynamics are used: the weak temperature gradient (WTG) approximation and the damped gravity wave (DGW) method. Both surface fluxes and radiative heating are specified, with radiative heating taken as constant in the vertical in the troposphere. All simulations are run to statistical equilibrium. In the precipitating equilibria, which result from sufficiently moist initial conditions, an increment in surface fluxes produces more precipitation than an equal increment of column-integrated radiative heating. This is straightforwardly understood in terms of the column-integrated moist static energy budget with constant normalized gross moist stability. Under both large-scale parameterizations, the gross moist stability does in fact remain close to constant over a wide range of forcings, and the small variations that occur are similar for equal increments of surface flux and radiative heating. With completely dry initial conditions, the WTG simulations exhibit hysteresis, maintaining a dry state with no precipitation for a wide range of net energy inputs to the atmospheric column. The same boundary conditions and forcings admit a rainy state also (for moist initial conditions), and thus multiple equilibria exist under WTG. When the net forcing (surface fluxes minus radiative heating) is increased enough that simulations that begin dry eventually develop precipitation, the dry state persists longer after initialization when the surface fluxes are increased than when radiative heating is increased. The DGW method, however, shows no multiple equilibria in any of the simulations.

scholarly journals Positional effects of second-sphere amide pendants on electrochemical CO2 reduction catalyzed by iron porphyrins

2018 ◽  
Vol 9 (11) ◽  
pp. 2952-2960 ◽  
Author(s):  
Eva M. Nichols ◽  
Jeffrey S. Derrick ◽  
Sepand K. Nistanaki ◽  
Peter T. Smith ◽  
Christopher J. Chang
Keyword(s):  
Carbon Dioxide ◽  
Greenhouse Gas ◽  
Electrochemical Reduction ◽  
Energy Input ◽  
Sustainable Energy ◽  
Co2 Reduction ◽  
Value Added ◽  
Iron Porphyrins ◽  
Electrochemical Co2 Reduction ◽  
Positional Effects

The development of catalysts for electrochemical reduction of carbon dioxide offers an attractive approach to transforming this greenhouse gas into value-added carbon products with sustainable energy input.

Characteristic Equation Development for Single-Slope Solar Distiller Unit Augmented With N Identical Parabolic Concentrator Integrated Evacuated Tubular Collectors

2019 ◽  
Vol 142 (2) ◽  
Author(s):  
Rajeev Kumar ◽  
Rahul Sharma ◽  
Dharmendra Kumar ◽  
Ajay R. Singh ◽  
Desh B. Singh ◽  
...  
Keyword(s):  
Flat Plate ◽  
Characteristic Equation ◽  
Energy Input ◽  
Mean Value ◽  
Energy Output ◽  
Net Energy ◽  
Solar Still ◽  
The Mean ◽  
Flat Plate Collector ◽  
Basin Area

Abstract In this communication, characteristic equation for single-slope solar still augmented with N alike parabolic concentrator integrated evacuated tubular collectors has been developed which is also valid for N alike evacuated tubular collectors integrated single-slope solar distiller unit as well as passive single-slope solar distiller unit. The developed equation is similar in the form to Hottel-Whillier-Bliss equation which was developed for flat plate collector. The analytical equation development for the proposed system involves the writing of equations for its different components on the ground of equating net energy input to net energy output. The results obtained for the proposed system have been compared with the results of N alike evacuated tubular collectors integrated single-slope solar distiller unit and passive single-slope solar distiller unit. It has been concluded that the mean value of instantaneous efficiency for N alike parabolic concentrator integrated evacuated tubular collectors is higher by 42.86% and 50.82%; daily generation of freshwater is higher by 49.73% and 74.34%; and daily exergy is higher by 78.71% and 93.35% than the corresponding values for N alike evacuated tubular collector integrated single-slope solar distiller unit and passive single-slope solar distiller unit for the same basin area in that order.

scholarly journals Fatigue Cycles and Performance Evaluation of Accelerating Aging Heat Treated Aluminum Semi Solid Materials Designed for Automotive Dynamic Components

2020 ◽  
Vol 10 (9) ◽  
pp. 3008
Author(s):  
Mohamed Attia ◽  
Khaled Ahmed Ragab ◽  
Mohamed Bouazara ◽  
X.-Grant Chen
Keyword(s):  
Fatigue Life ◽  
Thermal Aging ◽  
Weight Ratio ◽  
Dynamic Component ◽  
Specific Strength ◽  
Suspension Control ◽  
Dynamic Components ◽  
Semi Solid ◽  
Automotive Suspension ◽  
Von Mises

The A357-type (Al-Si-Mg) aluminum semi solid casting materials are known for their excellent strength and good ductility, which make them materials of choice, preferable in the manufacturing of automotive dynamic mechanical components. Semi-solid casting is considered as an effective technique for the manufacturing of automotive mechanical dynamic components of superior quality performance and efficiency. The lower control arm in an automotive suspension system is the significant mechanical dynamic component responsible for linking the wheels of the vehicle to the chassis. A new trend is to manufacture this part from A357 aluminum alloy due to its lightweight, high specific strength, and better corrosion resistance than steel. This study proposes different designs of a suspension control arm developed, concerning its strength to weight ratio. Furthermore, this study aims to investigate the effect of accelerating thermal aging treatments on the fatigue life of bending fatigue specimens manufactured from alloy A357 using the Rheocasting semi-solid technology. The results revealed that the multiple aging cycles, of WC3, indicated superior fatigue life compared to standard thermal aging cycles. On the other hand, the proposed designs of automotive suspension control components showed higher strength-to-weight ratios, better stress distribution, and lower Von-Mises stresses compared to conventional designs.

scholarly journals Local and Remote Impacts of Aerosol Climate Forcing on Tropical Precipitation*

2005 ◽  
Vol 18 (22) ◽  
pp. 4621-4636 ◽  
Author(s):  
Chia Chou ◽  
J. David Neelin ◽  
Ulrike Lohmann ◽  
Johann Feichter
Keyword(s):  
Global Warming ◽  
Circulation Model ◽  
Local Effect ◽  
Surface Heat ◽  
Net Energy ◽  
Tropical Precipitation ◽  
Aerosol Forcing ◽  
Aerosol Absorption ◽  
Precipitation Anomalies ◽  
Gross Moist Stability

Abstract Mechanisms that determine the direct and indirect effects of aerosols on the tropical climate involve moist dynamical processes and have local and remote impacts on regional tropical precipitation. These mechanisms are examined in a climate model of intermediate complexity [quasi-equilibrium tropical circulation model (QTCM)] forced by prescribed aerosol forcing, which is obtained from a general circulation model (ECHAM4). The aerosol reflection is the dominant aerosol forcing, while the aerosol absorption has complex but much weaker influences on the regional tropical precipitation based on the ECHAM4 aerosol forcing. The local effect associated with aerosols contributes negative precipitation anomalies over convective regions by affecting the net energy flux into the atmospheric column. This net energy flux is controlled by the radiative forcing at the top of the atmosphere on time scales where surface heat flux is near equilibrium, balancing anomalous solar radiation by evaporation, longwave radiation, and sensible heat. Considering the aerosol absorption effect alone, the associated precipitation anomalies are slightly negative but small when surface heat fluxes are near equilibrium. Two effects found in global warming, the upped-ante mechanism and the anomalous gross moist stability mechanism, occur with opposite sign in the aerosol case. Both act as remote effects via the widespread cold tropospheric temperature anomalies induced by the aerosol forcing. In the upped-ante mechanism in global warming, a warm troposphere increases the low-level moisture “ante” required for convection, creating spatially varying moisture anomalies that disfavor precipitation on those margins of convective zones where the mean flow imports air from nonconvective regions. In the aerosol case here, a cool troposphere preferentially decreases moisture in convective regions, creating positive precipitation anomalies at inflow margins. In the anomalous gross moist stability mechanism for the aerosol case, the decrease in moisture in convective regions acts to enhance the gross moist stability, so convection and the associated precipitation are reduced. The partitioning between the aerosol local and remote effects on regional tropical precipitation differs spatially. Over convective regions that have high aerosol concentration, such as the South American region, the aerosol local effect contributes more negative precipitation anomalies than the anomalous gross moist stability mechanism in the QTCM simulations. On the other hand, the remote effect is more important over convective regions with small aerosol concentrations, such as the western Pacific Maritime Continent. Remote effects of midlatitude aerosol forcing have a substantial contribution to tropical anomalies.

scholarly journals Energetic Constraints on the Position of the Intertropical Convergence Zone

2014 ◽  
Vol 27 (13) ◽  
pp. 4937-4951 ◽  
Author(s):  
Tobias Bischoff ◽  
Tapio Schneider
Keyword(s):  
Global Warming ◽  
Energy Input ◽  
Energy Transport ◽  
Intertropical Convergence Zone ◽  
Radiative Energy ◽  
Convergence Zone ◽  
Net Energy ◽  
Lower Boundary Condition ◽  
Near Surface ◽  
Atmospheric Energy

The intertropical convergence zone (ITCZ) can shift meridionally on seasonal and longer time scales. Previous studies have shown that the latitude of the ITCZ is negatively correlated with cross-equatorial atmospheric energy transport. For example, the ITCZ shifts southward as the Northern Hemisphere cools and the northward cross-equatorial energy transport strengthens in response. It has remained unclear what controls the sensitivity of the ITCZ position to cross-equatorial energy transport and what other factors may lead to shifts of the ITCZ position. Here it is shown that the sensitivity of the ITCZ position to cross-equatorial energy transport depends on the net energy input to the equatorial atmosphere: the net radiative energy input minus any energy uptake by the oceans. Changes in this energy input can also lead to ITCZ shifts. The cross-equatorial energy transport is related through a series of approximations to interhemispheric asymmetries in the near-surface temperature distribution. The resulting theory of the ITCZ position is tested in idealized general circulation model simulations with a slab ocean as lower boundary condition. In the simulations, cross-equatorial energy transport increases under global warming (primarily because extratropical latent energy fluxes strengthen), and this shifts the ITCZ poleward. The ITCZ shifts equatorward if primarily the tropics warm in response to an increased net energy input to the equatorial atmosphere. The results have implications for explaining the varied response of the ITCZ to global or primarily tropical changes in the atmospheric energy balance, such as those that occur under global warming or El Niño.

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