Climate vs. carbon dioxide controls on biomass burning: a model analysis of the glacial-interglacial contrast

NASA Astrophysics Data System (ADS)

Calvo, M. Martin; Prentice, I. C.; Harrison, S. P.

2014-02-01

Climate controls fire regimes through its influence on the amount and types of fuel present and their dryness; CO2 availability, in turn, constrains primary production by limiting photosynthetic activity in plants. However, although fuel accumulation depends on biomass production, and hence CO2 availability, the links between atmospheric CO2 and biomass burning are not well known. Here a fire-enabled dynamic global vegetation model (the Land surface Processes and eXchanges model, LPX) is used to attribute glacial-interglacial changes in biomass burning to CO2 increase, which would be expected to increase primary production and therefore fuel loads even in the absence of climate change, vs. climate change effects. Four general circulation models provided Last Glacial Maximum (LGM) climate anomalies - that is, differences from the pre-industrial (PI) control climate - from the Palaeoclimate Modelling Intercomparison Project Phase 2, allowing the construction of four scenarios for LGM climate. Modelled carbon fluxes in biomass burning were corrected for the model's observed biases in contemporary biome-average values. With LGM climate and low CO2 (185 ppm) effects included, the modelled global flux was 70 to 80% lower at the LGM than in PI time. LGM climate with pre-industrial CO2 (280 ppm) however yielded unrealistic results, with global and Northern Hemisphere biomass burning fluxes greater than in the pre-industrial climate. Using the PI CO2 concentration increased the modelled LGM biomass burning fluxes for all climate models and latitudinal bands to between four and ten times their values under LGM CO2 concentration. It is inferred that a substantial part of the increase in biomass burning after the LGM must be attributed to the effect of increasing CO2 concentration on productivity and fuel load. Today, by analogy, both rising CO2 and global warming must be considered as risk factors for increasing biomass burning. Both effects need to be included in models to project future fire risks.

Climate change effects on runoff, catchment phosphorus loading and lake ecological state, and potential adaptations.

PubMed

Jeppesen, Erik; Kronvang, Brian; Meerhoff, Mariana; Søndergaard, Martin; Hansen, Kristina M; Andersen, Hans E; Lauridsen, Torben L; Liboriussen, Lone; Beklioglu, Meryem; Ozen, Arda; Olesen, Jørgen E

2009-01-01

Climate change may have profound effects on phosphorus (P) transport in streams and on lake eutrophication. Phosphorus loading from land to streams is expected to increase in northern temperate coastal regions due to higher winter rainfall and to a decline in warm temperate and arid climates. Model results suggest a 3.3 to 16.5% increase within the next 100 yr in the P loading of Danish streams depending on soil type and region. In lakes, higher eutrophication can be expected, reinforced by temperature-mediated higher P release from the sediment. Furthermore, a shift in fish community structure toward small and abundant plankti-benthivorous fish enhances predator control of zooplankton, resulting in higher phytoplankton biomass. Data from Danish lakes indicate increased chlorophyll a and phytoplankton biomass, higher dominance of dinophytes and cyanobacteria (most notably of nitrogen fixing forms), but lower abundance of diatoms and chrysophytes, reduced size of copepods and cladocerans, and a tendency to reduced zooplankton biomass and zooplankton:phytoplankton biomass ratio when lakes warm. Higher P concentrations are also seen in warm arid lakes despite reduced external loading due to increased evapotranspiration and reduced inflow. Therefore, the critical loading for good ecological state in lakes has to be lowered in a future warmer climate. This calls for adaptation measures, which in the northern temperate zone should include improved P cycling in agriculture, reduced loading from point sources, and (re)-establishment of wetlands and riparian buffer zones. In the arid Southern Europe, restrictions on human use of water are also needed, not least on irrigation.

Climate versus carbon dioxide controls on biomass burning: a model analysis of the glacial-interglacial contrast

NASA Astrophysics Data System (ADS)

Calvo, M. Martin; Prentice, I. C.; Harrison, S. P.

2014-11-01

Climate controls fire regimes through its influence on the amount and types of fuel present and their dryness. CO2 concentration constrains primary production by limiting photosynthetic activity in plants. However, although fuel accumulation depends on biomass production, and hence on CO2 concentration, the quantitative relationship between atmospheric CO2 concentration and biomass burning is not well understood. Here a fire-enabled dynamic global vegetation model (the Land surface Processes and eXchanges model, LPX) is used to attribute glacial-interglacial changes in biomass burning to an increase in CO2, which would be expected to increase primary production and therefore fuel loads even in the absence of climate change, vs. climate change effects. Four general circulation models provided last glacial maximum (LGM) climate anomalies - that is, differences from the pre-industrial (PI) control climate - from the Palaeoclimate Modelling Intercomparison Project Phase~2, allowing the construction of four scenarios for LGM climate. Modelled carbon fluxes from biomass burning were corrected for the model's observed prediction biases in contemporary regional average values for biomes. With LGM climate and low CO2 (185 ppm) effects included, the modelled global flux at the LGM was in the range of 1.0-1.4 Pg C year-1, about a third less than that modelled for PI time. LGM climate with pre-industrial CO2 (280 ppm) yielded unrealistic results, with global biomass burning fluxes similar to or even greater than in the pre-industrial climate. It is inferred that a substantial part of the increase in biomass burning after the LGM must be attributed to the effect of increasing CO2 concentration on primary production and fuel load. Today, by analogy, both rising CO2 and global warming must be considered as risk factors for increasing biomass burning. Both effects need to be included in models to project future fire risks.

Retrofitting impervious urban infrastructure with green technology for rainfall-runoff restoration, indirect reuse and pollution load reduction.

PubMed

Sansalone, John; Raje, Saurabh; Kertesz, Ruben; Maccarone, Kerrilynn; Seltzer, Karl; Siminari, Michele; Simms, Peter; Wood, Brandon

2013-12-01

The built environs alter hydrology and water resource chemistry. Florida is subject to nutrient criteria and is promulgating "no-net-load-increase" criteria for runoff and constituents (nutrients and particulate matter, PM). With such criteria, green infrastructure, hydrologic restoration, indirect reuse and source control are potential design solutions. The study simulates runoff and constituent load control through urban source area re-design to provide long-term "no-net-load-increases". A long-term continuous simulation of pre- and post-development response for an existing surface parking facility is quantified. Retrofits include a biofiltration area reactor (BAR) for hydrologic and denitrification control. A linear infiltration reactor (LIR) of cementitious permeable pavement (CPP) provides infiltration, adsorption and filtration. Pavement cleaning provided source control. Simulation of climate and source area data indicates re-design achieves "no-net-load-increases" at lower costs compared to standard construction. The retrofit system yields lower cost per nutrient load treated compared to Best Management Practices (BMPs). Copyright © 2013 Elsevier Ltd. All rights reserved.

Advanced Thermo-Adsorptive Battery: Advanced Thermo-Adsorptive Battery Climate Control System

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

HEATS Project: MIT is developing a low-cost, compact, high-capacity, advanced thermoadsorptive battery (ATB) for effective climate control of EVs. The ATB provides both heating and cooling by taking advantage of the materials’ ability to adsorb a significant amount of water. This efficient battery system design could offer up as much as a 30% increase in driving range compared to current EV climate control technology. The ATB provides high-capacity thermal storage with little-to-no electrical power consumption. The ATB is also looking to explore the possibility of shifting peak electricity loads for cooling and heating in a variety of other applications, includingmore » commercial and residential buildings, data centers, and telecom facilities.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rudd, A.

This document covers a description of the need and applied solutions for supplemental dehumidification in warm-humid climates, especially for energy efficient homes where the sensible cooling load has been dramatically reduced. In older homes in warm-humid climates, cooling loads are typically high and cooling equipment runs a lot to cool the air. The cooling process also removes indoor moisture, reducing indoor relative humidity. However, at current residential code levels, and especially for above-code programs, sensible cooling loads have been so dramatically reduced that the cooling system does not run a lot to cool the air, resulting in much less moisturemore » being removed. In these new homes, cooling equipment is off for much longer periods of time especially during spring/fall seasons, summer shoulder months, rainy periods, some summer nights, and some winter days. In warm-humid climates, those long off periods allow indoor humidity to become elevated due to internally generated moisture and ventilation air change. Elevated indoor relative humidity impacts comfort, indoor air quality, and building material durability. Industry is responding with supplemental dehumidification options, but that effort is really in its infancy regarding year-round humidity control in low-energy homes. Available supplemental humidity control options are discussed. Some options are less expensive but may not control indoor humidity as well as more expensive and comprehensive options. The best performing option is one that avoids overcooling and avoids adding unnecessary heat to the space by using waste heat from the cooling system to reheat the cooled and dehumidified air to room-neutral temperature.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rudd, Armin

This document covers a description of the need and applied solutions for supplemental dehumidification in warm-humid climates, especially for energy efficient homes where the sensible cooling load has been dramatically reduced. Cooling loads are typically high and cooling equipment runs a lot to cool the air in older homes in warm-humid climates. The cooling process also removes indoor moisture, reducing indoor relative humidity. However, at current residential code levels, and especially for above-code programs, sensible cooling loads have been so dramatically reduced that the cooling system does not run a lot to cool the air, resulting in much less moisturemore » being removed. In these new homes, cooling equipment is off for much longer periods of time especially during spring/fall seasons, summer shoulder months, rainy periods, some summer nights, and winter days. In warm-humid climates, those long-off periods allow indoor humidity to become elevated due to internally generated moisture and ventilation air change. Elevated indoor relative humidity impacts comfort, indoor air quality, and building material durability. Industry is responding with supplemental dehumidification options, but that effort is really in its infancy regarding year-round humidity control in low-energy homes. Available supplemental humidity control options are discussed. Some options are less expensive but may not control indoor humidity as well as more expensive and comprehensive options. The best performing option is one that avoids overcooling and adding unnecessary heat to the space by using waste heat from the cooling system to reheat the cooled and dehumidified air to room-neutral temperature.« less

Export of dissolved organic matter in relation to land use along a European climatic gradient.

PubMed

Mattsson, Tuija; Kortelainen, Pirkko; Laubel, Anker; Evans, Dylan; Pujo-Pay, Mireille; Räike, Antti; Conan, Pascal

2009-03-01

The terrestrial export of dissolved organic matter (DOM) is associated with climate, vegetation and land use, and thus is under the influence of climatic variability and human interference with terrestrial ecosystems, their soils and hydrological cycles. We present a data-set including catchments from four areas covering the major climate and land use gradients within Europe: a forested boreal zone (Finland), a temperate agricultural area (Denmark), a wet and temperate mountain region in Wales, and a warm Mediterranean catchment draining into the Gulf of Lyon. In all study areas, DOC (dissolved organic carbon) was a major fraction of DOM, with much lower proportions of DON (dissolved organic nitrogen) and DOP (dissolved organic phosphorus). A south-north gradient with highest DOC concentrations and export in the northernmost catchments was recorded: DOC concentrations and loads were highest in Finland and lowest in France. These relationships indicate that DOC concentrations/export are controlled by several factors including wetland and forest cover, precipitation and hydrological processes. DON concentrations and loads were highest in the Danish catchments and lowest in the French catchments. In Wales and Finland, DON concentrations increased with the increasing proportion of agricultural land in the catchment, whereas in Denmark and France no such relationship was found. DOP concentrations and loads were low compared to DOC and DON. The highest DOP concentrations and loads were recorded in catchments with a high extent of agricultural land, large urban areas or a high population density, reflecting the influence of human impact on DOP loads.

Suspended sediment load, climate and relief in the central Pamirs

NASA Astrophysics Data System (ADS)

Pohl, Eric; Gloaguen, Richard; Andermann, Christoff; Schön, Ariane

2013-04-01

Relief and climate affect the generation of sediment transport. While relief and climate also affect each other, their influence on sediment transport can be investigated separately to determine their direct impact on this matter. Taking into account the complex topography of the central Pamirs and the fact that this region marks the transition zone of the Westerlies and the northward Indian Summer Monsoon, this region provides an excellent basis to investigate the interrelationship between sediment transport, climate and relief. The Panj River and its tributaries are representative for the hydrological setting of the central Pamirs as they drain most of the region. We first present suspended sediment characteristics from historical archive data for the whole river catchment and for the sub-catchments. We show the dynamics of the relationship between suspended sediment concentration and discharge on an annual basis for the different catchment sizes. The uppermost catchments are characterized by a transport-limited situation, showing a simple power-law relationship between discharge and sediment concentration for the entire year. The lowermost catchments show a strong hysteresis effect, especially in spring, which is related to the onset of snowmelt. The result is a differentiated power-law relationship within a year. As snow and glacier melt control the discharge in the central Pamirs, we investigate the climatological conditions derived from remote sensing data. We do this with respect to the different sub-catchments and with a special focus on the temporal variability. Results from the previous steps are finally interrelated with calculated geomorphological features at different catchment scales to characterize the suspended sediment load in the context of both relief and climatic conditions. Our results suggest climate to play the first-order determinant for the generation of suspended sediment load. This is in particular due to the Westerlies that provide the bulk of precipitation as snow in winter. Eventually temperature triggers snowmelt and causes high sediment loads. Still, relief causes the sediment load indirectly by forcing the climatic setting and providing the potential energy for stream flow.

Mitigating cyanobacterial harmful algal blooms in aquatic ecosystems impacted by climate change and anthropogenic nutrients.

PubMed

Paerl, Hans W; Gardner, Wayne S; Havens, Karl E; Joyner, Alan R; McCarthy, Mark J; Newell, Silvia E; Qin, Boqiang; Scott, J Thad

2016-04-01

Mitigating the global expansion of cyanobacterial harmful blooms (CyanoHABs) is a major challenge facing researchers and resource managers. A variety of traditional (e.g., nutrient load reduction) and experimental (e.g., artificial mixing and flushing, omnivorous fish removal) approaches have been used to reduce bloom occurrences. Managers now face the additional effects of climate change on watershed hydrologic and nutrient loading dynamics, lake and estuary temperature, mixing regime, internal nutrient dynamics, and other factors. Those changes favor CyanoHABs over other phytoplankton and could influence the efficacy of control measures. Virtually all mitigation strategies are influenced by climate changes, which may require setting new nutrient input reduction targets and establishing nutrient-bloom thresholds for impacted waters. Physical-forcing mitigation techniques, such as flushing and artificial mixing, will need adjustments to deal with the ramifications of climate change. Here, we examine the suite of current mitigation strategies and the potential options for adapting and optimizing them in a world facing increasing human population pressure and climate change. Copyright © 2015 Elsevier B.V. All rights reserved.

Seasonal Response of Overland Flow and Sediment Loading to Climate and Land Use Land Cover Change in the Apalachicola River, Florida

NASA Astrophysics Data System (ADS)

Hovenga, P. A.; Wang, D.; Medeiros, S. C.; Hagen, S. C.

2015-12-01

Located in Florida's panhandle, the Apalachicola River is the southernmost reach of the Apalachicola-Chattahoochee-Flint (ACF) River basin. Streamflow and sediment drains to Apalachicola Bay within the Northern Gulf of Mexico, resulting in a direct influence on the ecology of the region, in particular seagrass and oyster production. This study examines the seasonal response of overland flow and sediment loading in the Apalachicola River under projected climate change scenarios and land use land cover (LULC) change. A hydrologic model using the Soil Water Assessment Tool (SWAT) was developed for the Apalachicola region to simulate daily discharge and sediment load under present (circa 2000) and future conditions (circa 2100) to understand how parameters respond over a seasonal time frame to changes in climate only, LULC only, and coupled climate / LULC. These physically-based models incorporate digital elevation model (DEM), LULC, soil maps, climate data, and management controls. Long Ashton Research Station-Weather Generator (LARS-WG) was used to create stochastic temperature and precipitation inputs from four Global Climate Models (GCM), each under Intergovernmental Panel on Climate Change (IPCC) carbon emission scenarios for A1B, A2, and B1. These scenarios represent potential future emissions resulting from a range driving forces, e.g. social, economic, environmental, and technologic. Projected 2100 LULC data provided by the United States Geological Survey (USGS) EROS Center was incorporated for each corresponding IPCC scenario. Results from this study can be used to further understand climate and LULC implications to the Apalachicola Bay and surrounding region as well as similar fluvial estuaries while providing tools to better guide management and mitigation practices.

Heat stress and carbon monoxide exposure during C-130 vehicle transportation.

PubMed

Dor, Alex; Pokroy, Russell; Goldstein, Liav; Barenboim, Erez; Zilberberg, Michal

2005-04-01

Running gasoline engines in a confined space causes heat stress and carbon monoxide (CO) buildup. Loading the C-130 aircraft by driving the vehicles onto the platform may expose the C-130 cabin crew to these environmental hazards. This study was aimed at investigating heat stress and CO exposure in the C-130 cabin during vehicle airlift. There were four summer flights (two two-vehicle, two three-vehicle; 2 d, 2 nights) studied. The cabin heat stress index (wet bulb globe temperature, WBGT) and CO levels before vehicle loading (control) were compared with those after vehicle loading. Furthermore, two- and three-vehicle transportations, as well as day and night transportations, were compared. Ground temperature ranged from 18.2 to 33.4 degrees C. Mean heat stress index was higher in vehicle transportation than control flights, the greatest difference being 5.9 degrees C (p < 0.001). The WBGT levels exceeded the recommended exposure limit in 28 of 38 measurements during day flights. The cabin heat stress increased sharply with vehicle loading, and continued to increase for a range of 60-140 min after loading. Elevated cabin CO levels were found in three-vehicle flights as compared with two, and in night flights as compared with day. In hot climates, C-130 vehicle transportation may exacerbate heat stress. The in-flight heat stress can be predicted by the ambient temperature, duration of the vehicle transportation, and number of transported vehicles. The cabin CO level is related to the number of transported vehicles. We recommend the use of effective environmental control systems during C-130 vehicle transportation in hot climates.

Climate change impacts on runoff, sediment, and nutrient loads in an agricultural watershed in the Lower Mississippi River Basin

USDA-ARS?s Scientific Manuscript database

Projected climate change can impact various aspects of agricultural systems, including the nutrient and sediment loads exported from agricultural fields. This study evaluated the potential changes in runoff, sediment, nitrogen, and phosphorus loads using projected climate estimates from 2041 – 2070 ...

The importance of considering shifts in seasonal changes in discharges when predicting future phosphorus loads in streams

USGS Publications Warehouse

LaBeau, Meredith B.; Mayer, Alex S.; Griffis, Veronica; Watkins, David Jr.; Robertson, Dale M.; Gyawali, Rabi

2015-01-01

In this work, we hypothesize that phosphorus (P) concentrations in streams vary seasonally and with streamflow and that it is important to incorporate this variation when predicting changes in P loading associated with climate change. Our study area includes 14 watersheds with a range of land uses throughout the U.S. Great Lakes Basin. We develop annual seasonal load-discharge regression models for each watershed and apply these models with simulated discharges generated for future climate scenarios to simulate future P loading patterns for two periods: 2046–2065 and 2081–2100. We utilize output from the Coupled Model Intercomparison Project phase 3 downscaled climate change projections that are input into the Large Basin Runoff Model to generate future discharge scenarios, which are in turn used as inputs to the seasonal P load regression models. In almost all cases, the seasonal load-discharge models match observed loads better than the annual models. Results using the seasonal models show that the concurrence of nonlinearity in the load-discharge model and changes in high discharges in the spring months leads to the most significant changes in P loading for selected tributaries under future climate projections. These results emphasize the importance of using seasonal models to understand the effects of future climate change on nutrient loads.

Drivers of lignin composition in boreal forest organic soils across a climate gradient

NASA Astrophysics Data System (ADS)

Myers-Pigg, A.; Kaiser, K.; Benner, R. H.; Ziegler, S. E.

2017-12-01

Lignin diagenesis in soils, including the cumulative effects of degradation and leaching, increases with experimental warming, signifying a potentially important change relevant to soil organic matter accumulation and fate. However, decadal to centennial climatic effects including changes in precipitation, litterfall inputs, and understory sources, on lignin composition are poorly constrained. We examined the lignin content and composition, via cupric oxide oxidation (CuO), within the organic layers of podzolic soils under similar balsam fir forests across a latitudinal climate gradient in Atlantic Canada. By exploring variation in lignin by both soil depth and climate region, this study informs on the climate drivers of lignin stability within boreal forest soil. A two-way analysis of variance (ANOVA) revealed significant variations in common signatures of CuO by-products with depth and/or site, indicating source and/or diagenetic controllers. Importantly, none of these signatures, with the exception of p-hydroxyphenols, exhibited a site by depth interaction indicating a similar degree of diagenetic alternation with depth across climates. The site by depth interaction for p-hydroxyphenols is a result of greater moss input in the northernmost site. To better elucidate this climate-induced source variation on our interpretation of lignin diagenesis, a principle component (PCA) model was built using signatures varying by site (p<0.01). These signatures loaded uniquely with the percentage of wood, needles, and mosses within the L layer in each region. Site differences in this loading indicate that shifts in understory input is a major climate effect controlling lignin composition in these forest soils. A lignin diagenesis PCA model was built using (1) all non-moss related signatures identified in the first PCA model, and (2) scores for additional sites within each region, calculated from modeled lignin composition based on 13C-NMR spectra. The combined results indicate that the lignin diagenetic states among soils is similar, despite the large increase in soil C turnover with climate warming across this transect. Thus our results indicate that shifts in moss contribution, and not increased diagenesis, controls CuO by-products with climate change in these moist boreal forests.

Evaluating Moisture Control of Variable-Capacity Heat Pumps in Mechanically Ventilated, Low-Load Homes in Climate Zone 2A

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martin, Eric; Withers, Chuck; McIlvaine, Janet

Low-load homes can present a challenge when selecting appropriate space-conditioning equipment. Conventional, fixed-capacity heating and cooling equipment is often oversized for small homes, causing increased first costs and operating costs. This report evaluates the performance of variable-capacity comfort systems, with a focus on inverter-driven, variable-capacity systems, as well as proposed system enhancements.

Pollutant loading from low-density residential neighborhoods in California.

PubMed

Bale, Andrew E; Greco, Steven E; Pitton, Bruno J L; Haver, Darren L; Oki, Lorence R

2017-08-01

This paper presents a comparison of pollutant load estimations for runoff from two geographically distinct residential suburban neighborhoods in northern and southern California. The two neighborhoods represent a single urban land use type: low-density residential in small catchments (<0.3 km 2 ) under differing regional climates and irrigation practices. Pollutant loads of pesticides, nutrients, and drinking water constituents of concern are estimated for both storm and non-storm runoff. From continuous flow monitoring, it was found that a daily cycle of persistent runoff that peaks mid-morning occurs at both sites. These load estimations indicate that many residential neighborhoods in California produce significant non-storm pollutant loads year-round. Results suggest that non-storm flow accounted for 47-69% of total annual runoff and significantly contributed to annual loading rates of most nutrients and pesticides at both sites. At the Southern California site, annual non-storm loads are 1.2-10 times higher than storm loads of all conventional constituents and nutrients with one exception (total suspended solids). At the Northern California site, annual storm loads range from 51 to 76% of total loads for all conventional constituents and nutrients with one exception (total dissolved solids). Non-storm yields of pesticides at the Southern California site range from 1.3-65 times higher than those at the Northern California site. The disparity in estimated pollutant loads between the two sites indicates large potential variation from site-to-site within the state and suggests neighborhoods in drier and milder climates may produce significantly larger non-storm loads due to persistent dry season runoff and year-round pest control.

Launchers and Improved Components for 4.5 in. Rockets

DTIC Science & Technology

1946-02-09

Engagements 132 Loading 133 Release 133 "Dig In" Characteristic 133 Cushioning 134 TABLE OF CONTENTS (Conttd) PAGE *Overshooting" in Loading 134 Effect on... loaded for a cold climate and used in a hot climate without removing some of the propellent powder there will be danger of its bursting. Conversely, if...it is loaded for use in a hot climate, there vwill not be sufficient powder for firing at low temperature. A regulating pressure device that would

Skylight energy performance and design optimization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arasteh, D.; Johnson, R.; Selkowitz, S.

1984-02-01

Proper skylight utilization can significantly lower energy requirements and peak electrical loads for space conditioning and lighting in commercial buildings. In this study we systematically explore the energy effects of skylight systems in a prototypical office building and examine the savings from daylighting. The DOE-2.1B energy analysis computer program with its newly incorporated daylighting algorithms was used to generate more than 2000 parametric simulations for seven US climates. The parameters varied include skylight-to-roof ratio, shading coefficient, visible transmittance, skylight well light loss, electric lighting power density, roof heat transfer coefficient, and type of electric lighting control. For specific climates wemore » identify roof/skylight characteristics that minimize total energy or peak electrical load requirements.« less

Future nutrient load scenarios for the Baltic Sea due to climate and lifestyle changes.

PubMed

Hägg, Hanna Eriksson; Lyon, Steve W; Wällstedt, Teresia; Mörth, Carl-Magnus; Claremar, Björn; Humborg, Christoph

2014-04-01

Dynamic model simulations of the future climate and projections of future lifestyles within the Baltic Sea Drainage Basin (BSDB) were considered in this study to estimate potential trends in future nutrient loads to the Baltic Sea. Total nitrogen and total phosphorus loads were estimated using a simple proxy based only on human population (to account for nutrient sources) and stream discharges (to account for nutrient transport). This population-discharge proxy provided a good estimate for nutrient loads across the seven sub-basins of the BSDB considered. All climate scenarios considered here produced increased nutrient loads to the Baltic Sea over the next 100 years. There was variation between the climate scenarios such that sub-basin and regional differences were seen in future nutrient runoff depending on the climate model and scenario considered. Regardless, the results of this study indicate that changes in lifestyle brought about through shifts in consumption and population potentially overshadow the climate effects on future nutrient runoff for the entire BSDB. Regionally, however, lifestyle changes appear relatively more important in the southern regions of the BSDB while climatic changes appear more important in the northern regions with regards to future increases in nutrient loads. From a whole-ecosystem management perspective of the BSDB, this implies that implementation of improved and targeted management practices can still bring about improved conditions in the Baltic Sea in the face of a warmer and wetter future climate.

Window performance and building energy use: Some technical options for increasing energy efficiency

NASA Astrophysics Data System (ADS)

Selkowitz, Stephen

1985-11-01

Window system design and operation has a major impact on energy use in buildings as well as on occupants' thermal and visual comfort. Window performance will be a function of optical and thermal properties, window management strategies, climate and orientation, and building type and occupancy. In residences, heat loss control is a primary concern, followed by sun control in more southerly climates. In commercial buildings, the daylight provided by windows may be the major energy benefits but solar gain must be controlled so that increased cooling loads do not exceed daylighting savings. Reductions in peak electrical demand and HVAC system size may also be possible in well-designed daylighted buildings.

Impact assessment of projected climate change on diffuse phosphorous loss in Xin'anjiang catchment, China.

PubMed

Zhai, Xiaoyan; Zhang, Yongyong

2018-02-01

Diffuse nutrient loss is a serious threat to water security and has severely deteriorated water quality throughout the world. Xin'anjiang catchment, as a main drinking water source for Hangzhou City, has been a national concern for water environment protection with payment for watershed services construction. Detection of diffuse phosphorous (DP) pollution dynamics under climate change is significant for sustainable water quality management. In this study, the impact of projected climate change on DP load was analyzed using SWAT to simulate the future changes of diffuse components (carriers: water discharge and sediment; nutrient: DP) at both station and sub-catchment scales under three climate change scenarios (RCP2.6, RCP4.5, and RCP8.5). Results showed that wetting and warming years were expected with increasing tendencies of both precipitation and temperature in the two future periods (2020s: 2021~2030, 2030s: 2031~2040) except in the 2020s in the RCP2.6 scenario, and the annual average increasing ratios of precipitation and temperature reached - 1.79~3.79% and 0.48~1.27 °C, respectively, comparing with those in the baseline (2000s: 2001~2010). Climate change evidently altered annual and monthly average water discharge and sediment load, while it has a remarkable impact on the timing and monthly value of DP load at station scale. DP load tended to increase in the non-flood season at Yuliang due to strengthened nutrient flushing from rice land into rivers with increasing precipitation and enhanced phosphorous cycle in soil layers with increasing temperature, while it tended to decrease in the flood season at Yuliang and in most months at Tunxi due to restricted phosphorous reaction with reduced dissolved oxygen content and enhanced dilution effect. Spatial variability existed in the changes of sediment load and DP load at sub-catchment scale due to climate change. DP load tended to decrease in most sub-catchments and was the most remarkable in the RCP8.5 scenario (2020s, - 9.00~2.63%; 2030s, - 11.16~7.89%), followed by RCP2.6 (2020s, - 10.00~2.90%; 2030s, - 9.00~6.63%) and RCP4.5 (2020s, - 6.81~5.49%, 2030s, - 10.00~9.09%) scenarios. Decreasing of DP load mainly aggregated in the western and eastern mountainous regions, while it tended to increase in the northern and middle regions. This study was expected to provide insights into diffuse nutrient loss control and management in Xin'anjiang catchment, and scientific references for the implementation of water environmental protection in China.

Mapping Fuel Loads and Dynamics in Rangelands Using Multi-Sensor Data in the Great Basin, USA

NASA Astrophysics Data System (ADS)

Li, Z.; Shi, H.; Vogelmann, J. E.; Hawbaker, T. J.; Reeves, M. C.

2016-12-01

Fuel conditions in rangelands are influenced by disturbances such as wildfires, and is also strongly controlled by weather and climate. These factors impact the availability of fuel loads, which is the key component to stimulate burned area and severity. In this paper, we developed an approach for mapping live fuel loads (biomass density) and their dynamics using field collection, Landsat 8, and MODIS data sets at a spatial resolution of 30 m from the growing season. Using the Spatial and Temporal Adaptive Reflectance Fusion Model (STARFM) modelling process, we generated monthly shrub and grassland greenness levels for 2015. The spatial resolution of Landsat and the temporal resolution of MODIS complimented each other to allow us to produce monthly products. Understanding the dynamics of these greenness patterns helps the fire management community to recognize areas that have high likelihood of burning in the future, thus enabling them to anticipate and plan accordingly. We obtained field biomass information from selected shrub and grass sites located throughout the Great Basin. This information was used to calibrate fire models and generate remotely-sensed data sets. We then used Landsat 8 NDVI dates representing the phenological profile, regression tree models, and product validation. The calculated fuel loads were further examined and validated using high resolution images (World View 2/3), field measurements, and Google Earth. Once we have the requisite image data converted to biomass, we anticipate fire conditions and behavior using various models developed by the fire community. One key element is to use information from this study to improve and inform the Rangeland Vegetation Simulator. Finally, we analyzed the correlations of fire occurrence (frequency) and burn severity with live fuel loads and climate conditions. Our results show modeled fuel loads and their dynamics in rangelands capture the spatiotemporal heterogeneity of non-forest live fuel types and the variations in both wildfire disturbances and climate/weather conditions. This suggests the developed approach to map fuel loads is robust and can improve the existing LANDFIRE fuel data in rangelands. It can also be used to monitor the changes in fuel conditions in response to management activities and climate change.

Stream nitrate responses to hydrological forcing and climate change in northern forests of the USA (Invited)

NASA Astrophysics Data System (ADS)

Sebestyen, S. D.; Campbell, J. L.; Shanley, J. B.; Pourmokhtarian, A.; Driscoll, C. T.; Boyer, E. W.

2009-12-01

There is a need to understand how climate variability and change affect nutrient delivery to surface waters. We analyzed long-term records of hydrochemical data to explore how the forms, concentrations, and loadings of nitrogen in forest streams throughout the northern USA vary with catchment wetness. We considered projected changes in growing season length and precipitation patterns to simulate future climate scenarios and to assess how stream nitrate loading responds to hydrological forcing under different climate change scenarios. At the Sleepers River Research Watershed in northeastern Vermont, model results suggest that stream nutrient loadings over the next century will respond to hydrological forcing during climate change that affects the amount of water that flows through the landscape. For example, growing season stream water yield (+20%) and nitrate loadings (+57%) increase in response to greater amounts of precipitation (+28%) during a warmer climate with a longer growing season (+43 days). We further explore these findings by presenting model results from a biogeochemical process model (PnET-BGC) to separate changes that are due to biogeochemical cycling and the effects of hydrological forcing. Our findings suggest that nitrogen cycling and transport will intensify during anthropogenic climate forcing, thereby affecting the timing and magnitude of annual stream nutrient loadings in northern forests of the USA.

Variability in climate change simulations affects needed long-term riverine nutrient reductions for the Baltic Sea.

PubMed

Bring, Arvid; Rogberg, Peter; Destouni, Georgia

2015-06-01

Changes to runoff due to climate change may influence management of nutrient loading to the sea. Assuming unchanged river nutrient concentrations, we evaluate the effects of changing runoff on commitments to nutrient reductions under the Baltic Sea Action Plan. For several countries, climate projections point to large variability in load changes in relation to reduction targets. These changes either increase loads, making the target more difficult to reach, or decrease them, leading instead to a full achievement of the target. The impact of variability in climate projections varies with the size of the reduction target and is larger for countries with more limited commitments. In the end, a number of focused actions are needed to manage the effects of climate change on nutrient loads: reducing uncertainty in climate projections, deciding on frameworks to identify best performing models with respect to land surface hydrology, and increasing efforts at sustained monitoring of water flow changes.

Variability in climate change simulations affects needed long-term riverine nutrient reductions for the Baltic Sea

DOE PAGES

Bring, Arvid; Rogberg, Peter; Destouni, Georgia

2015-05-28

Changes to runoff due to climate change may influence management of nutrient loading to the sea. Assuming unchanged river nutrient concentrations, we evaluate the effects of changing runoff on commitments to nutrient reductions under the Baltic Sea Action Plan. For several countries, climate projections point to large variability in load changes in relation to reduction targets. These changes either increase loads, making the target more difficult to reach, or decrease them, leading instead to a full achievement of the target. The impact of variability in climate projections varies with the size of the reduction target and is larger for countriesmore » with more limited commitments. Finally, in the end, a number of focused actions are needed to manage the effects of climate change on nutrient loads: reducing uncertainty in climate projections, deciding on frameworks to identify best performing models with respect to land surface hydrology, and increasing efforts at sustained monitoring of water flow changes.« less

Variability in climate change simulations affects needed long-term riverine nutrient reductions for the Baltic Sea

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bring, Arvid; Rogberg, Peter; Destouni, Georgia

Changes to runoff due to climate change may influence management of nutrient loading to the sea. Assuming unchanged river nutrient concentrations, we evaluate the effects of changing runoff on commitments to nutrient reductions under the Baltic Sea Action Plan. For several countries, climate projections point to large variability in load changes in relation to reduction targets. These changes either increase loads, making the target more difficult to reach, or decrease them, leading instead to a full achievement of the target. The impact of variability in climate projections varies with the size of the reduction target and is larger for countriesmore » with more limited commitments. Finally, in the end, a number of focused actions are needed to manage the effects of climate change on nutrient loads: reducing uncertainty in climate projections, deciding on frameworks to identify best performing models with respect to land surface hydrology, and increasing efforts at sustained monitoring of water flow changes.« less

Impacts, recovery rates, and treatment options for spilled oil in marshes.

PubMed

Michel, Jacqueline; Rutherford, Nicolle

2014-05-15

In a review of the literature on impacts of spilled oil on marshes, 32 oil spills and field experiments were identified with sufficient data to generate recovery curves and identify influencing factors controlling the rate of recovery. For many spills, recovery occurred within 1-2 growing seasons, even in the absence of any treatment. Recovery was longest for spills with the following conditions: Cold climate; sheltered settings; thick oil on the marsh surface; light refined products with heavy loading; oils that formed persistent thick residues; and intensive treatment. Recovery was shortest for spills with the following conditions: Warm climate; light to heavy oiling of the vegetation only; medium crude oils; and less-intensive treatment. Recommendations are made for treatment based on the following oiling conditions: Free-floating oil on the water in the marsh; thicker oil (>0.5 cm) on marsh surface; thinner oil (<0.5 cm) on marsh surface; heavy oil loading on vegetation; and light to moderate oil loading on vegetation. Copyright © 2014 Elsevier Ltd. All rights reserved.

The prediction of the impact of climatic factors on short-term electric power load based on the big data of smart city

NASA Astrophysics Data System (ADS)

Qiu, Yunfei; Li, Xizhong; Zheng, Wei; Hu, Qinghe; Wei, Zhanmeng; Yue, Yaqin

2017-08-01

The climate changes have great impact on the residents’ electricity consumption, so the study on the impact of climatic factors on electric power load is of significance. In this paper, the effects of the data of temperature, rainfall and wind of smart city on short-term power load is studied to predict power load. The authors studied the relation between power load and daily temperature, rainfall and wind in the 31 days of January of one year. In the research, the authors used the Matlab neural network toolbox to establish the combinational forecasting model. The authors trained the original input data continuously to get the internal rules inside the data and used the rules to predict the daily power load in the next January. The prediction method relies on the accuracy of weather forecasting. If the weather forecasting is different from the actual weather, we need to correct the climatic factors to ensure accurate prediction.

Stochastic Controls on Nitrate Transport and Cycling

NASA Astrophysics Data System (ADS)

Botter, G.; Settin, T.; Alessi Celegon, E.; Marani, M.; Rinaldo, A.

2005-12-01

In this paper, the impact of nutrient inputs on basin-scale nitrates losses is investigated in a probabilistic framework by means of a continuous, geomorphologically based, Montecarlo approach, which explicitly tackles the random character of the processes controlling nitrates generation, transformation and transport in river basins. This is obtained by coupling the stochastic generation of climatic and rainfall series with simplified hydrologic and biogeochemical models operating at the hillslope scale. Special attention is devoted to the spatial and temporal variability of nitrogen sources of agricultural origin and to the effect of temporally distributed rainfall fields on the ensuing nitrates leaching. The influence of random climatic variables on bio-geochemical processes affecting the nitrogen cycle in the soil-water system (e.g. plant uptake, nitrification and denitrification, mineralization), is also considered. The approach developed has been applied to a catchment located in North-Eastern Italy and is used to provide probabilistic estimates of the NO_3 load transferred downstream, which is received and accumulated in the Venice lagoon. We found that the nitrogen load introduced by fertilizations significantly affects the pdf of the nitrates content in the soil moisture, leading to prolonged risks of increased nitrates leaching from soil. The model allowed the estimation of the impact of different practices on the probabilistic structure of the basin-scale hydrologic and chemical response. As a result, the return period of the water volumes and of the nitrates loads released into the Venice lagoon has been linked directly to the ongoing climatic, pluviometric and agricultural regimes, with relevant implications for environmental planning activities aimed at achieving sustainable management practices.

Heavy snow loads in Finnish forests respond regionally asymmetrically to projected climate change

DOE PAGES

Lehtonen, Ilari; Kamarainen, Matti; Gregow, Hilppa; ...

2016-10-17

This study examined the impacts of projected climate change on heavy snow loads on Finnish forests, where snow-induced forest damage occurs frequently. For snow-load calculations, we used daily data from five global climate models under representative concentration pathway (RCP) scenarios RCP4.5 and RCP8.5, statistically downscaled onto a high-resolution grid using a quantile-mapping method. Our results suggest that projected climate warming results in regionally asymmetric response on heavy snow loads in Finnish forests. In eastern and northern Finland, the annual maximum snow loads on tree crowns were projected to increase during the present century, as opposed to southern and western parts ofmore » the country. The change was rather similar both for heavy rime loads and wet snow loads, as well as for frozen snow loads. Only the heaviest dry snow loads were projected to decrease over almost the whole of Finland. Our results are aligned with previous snowfall projections, typically indicating increasing heavy snowfalls over the areas with mean temperature below -8 °C. In spite of some uncertainties related to our results, we conclude that the risk for snow-induced forest damage is likely to increase in the future in the eastern and northern parts of Finland, i.e. in the areas experiencing the coldest winters in the country. In conclusion, the increase is partly due to the increase in wet snow hazards but also due to more favourable conditions for rime accumulation in a future climate that is more humid but still cold enough.« less

Heavy snow loads in Finnish forests respond regionally asymmetrically to projected climate change

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lehtonen, Ilari; Kamarainen, Matti; Gregow, Hilppa

This study examined the impacts of projected climate change on heavy snow loads on Finnish forests, where snow-induced forest damage occurs frequently. For snow-load calculations, we used daily data from five global climate models under representative concentration pathway (RCP) scenarios RCP4.5 and RCP8.5, statistically downscaled onto a high-resolution grid using a quantile-mapping method. Our results suggest that projected climate warming results in regionally asymmetric response on heavy snow loads in Finnish forests. In eastern and northern Finland, the annual maximum snow loads on tree crowns were projected to increase during the present century, as opposed to southern and western parts ofmore » the country. The change was rather similar both for heavy rime loads and wet snow loads, as well as for frozen snow loads. Only the heaviest dry snow loads were projected to decrease over almost the whole of Finland. Our results are aligned with previous snowfall projections, typically indicating increasing heavy snowfalls over the areas with mean temperature below -8 °C. In spite of some uncertainties related to our results, we conclude that the risk for snow-induced forest damage is likely to increase in the future in the eastern and northern parts of Finland, i.e. in the areas experiencing the coldest winters in the country. In conclusion, the increase is partly due to the increase in wet snow hazards but also due to more favourable conditions for rime accumulation in a future climate that is more humid but still cold enough.« less

Carbonaceous aerosol tracers in ice-cores record multi-decadal climate oscillations

PubMed Central

Seki, Osamu; Kawamura, Kimitaka; Bendle, James A. P.; Izawa, Yusuke; Suzuki, Ikuko; Shiraiwa, Takayuki; Fujii, Yoshiyuki

2015-01-01

Carbonaceous aerosols influence the climate via direct and indirect effects on radiative balance. However, the factors controlling the emissions, transport and role of carbonaceous aerosols in the climate system are highly uncertain. Here we investigate organic tracers in ice cores from Greenland and Kamchatka and find that, throughout the period covered by the records (1550 to 2000 CE), the concentrations and composition of biomass burning-, soil bacterial- and plant wax- tracers correspond to Arctic and regional temperatures as well as the warm season Arctic Oscillation (AO) over multi-decadal time-scales. Specifically, order of magnitude decreases (increases) in abundances of ice-core organic tracers, likely representing significant decreases (increases) in the atmospheric loading of carbonaceous aerosols, occur during colder (warmer) phases in the high latitudinal Northern Hemisphere. This raises questions about causality and possible carbonaceous aerosol feedback mechanisms. Our work opens new avenues for ice core research. Translating concentrations of organic tracers (μg/kg-ice or TOC) from ice-cores, into estimates of the atmospheric loading of carbonaceous aerosols (μg/m3) combined with new model constraints on the strength and sign of climate forcing by carbonaceous aerosols should be a priority for future research. PMID:26411576

Capturing interactions between nitrogen and hydrological cycles under historical climate and land use: Susquehanna watershed analysis with the GFDL land model LM3-TAN

USGS Publications Warehouse

Lee, M.; Malyshev, S.; Shevliakova, E.; Milly, Paul C. D.; Jaffé, P. R.

2014-01-01

We developed a process model LM3-TAN to assess the combined effects of direct human influences and climate change on terrestrial and aquatic nitrogen (TAN) cycling. The model was developed by expanding NOAA's Geophysical Fluid Dynamics Laboratory land model LM3V-N of coupled terrestrial carbon and nitrogen (C-N) cycling and including new N cycling processes and inputs such as a soil denitrification, point N sources to streams (i.e., sewage), and stream transport and microbial processes. Because the model integrates ecological, hydrological, and biogeochemical processes, it captures key controls of the transport and fate of N in the vegetation–soil–river system in a comprehensive and consistent framework which is responsive to climatic variations and land-use changes. We applied the model at 1/8° resolution for a study of the Susquehanna River Basin. We simulated with LM3-TAN stream dissolved organic-N, ammonium-N, and nitrate-N loads throughout the river network, and we evaluated the modeled loads for 1986–2005 using data from 16 monitoring stations as well as a reported budget for the entire basin. By accounting for interannual hydrologic variability, the model was able to capture interannual variations of stream N loadings. While the model was calibrated with the stream N loads only at the last downstream Susquehanna River Basin Commission station Marietta (40°02' N, 76°32' W), it captured the N loads well at multiple locations within the basin with different climate regimes, land-use types, and associated N sources and transformations in the sub-basins. Furthermore, the calculated and previously reported N budgets agreed well at the level of the whole Susquehanna watershed. Here we illustrate how point and non-point N sources contributing to the various ecosystems are stored, lost, and exported via the river. Local analysis of six sub-basins showed combined effects of land use and climate on soil denitrification rates, with the highest rates in the Lower Susquehanna Sub-Basin (extensive agriculture; Atlantic coastal climate) and the lowest rates in the West Branch Susquehanna Sub-Basin (mostly forest; Great Lakes and Midwest climate). In the re-growing secondary forests, most of the N from non-point sources was stored in the vegetation and soil, but in the agricultural lands most N inputs were removed by soil denitrification, indicating that anthropogenic N applications could drive substantial increase of N2O emission, an intermediate of the denitrification process.

Climate-scale modelling of suspended sediment load in an Alpine catchment debris flow (Rio Cordon-northeastern Italy)

NASA Astrophysics Data System (ADS)

Diodato, Nazzareno; Mao, Luca; Borrelli, Pasquale; Panagos, Panos; Fiorillo, Francesco; Bellocchi, Gianni

2018-05-01

Pulsing storms and prolonged rainfall can drive hydrological damaging events in mountain regions with soil erosion and debris flow in river catchments. The paper presents a parsimonious model for estimating climate forcing on sediment loads in an Alpine catchment (Rio Cordon, northeastern Italian Alps). Hydroclimatic forcing was interpreted by the novel CliSMSSL (Climate-Scale Modelling of Suspended Sediment Load) model to estimate annual sediment loads. We used annual data on suspended-solid loads monitored at an experimental station from 1987 to 2001 and on monthly precipitation data. The quality of sediment load data was critically examined, and one outlying year was identified and removed from further analyses. This outlier revealed that our model underestimates exceptionally high sediment loads in years characterized by a severe flood event. For all other years, the CliSMSSL performed well, with a determination coefficient (R2) equal to 0.67 and a mean absolute error (MAE) of 129 Mg y-1. The calibrated model for the period 1986-2010 was used to reconstruct sediment loads in the river catchment for historical times when detailed precipitation records are not available. For the period 1810-2010, the model results indicate that the past centuries have been characterized by large interannual to interdecadal fluctuations in the conditions affecting sediment loads. This paper argues that climate-induced erosion processes in Alpine areas and their impact on environment should be given more attention in discussions about climate-driven strategies. Future work should focus on delineating the extents of these findings (e.g., at other catchments of the European Alpine belt) as well as investigating the dynamics for the formation of sediment loads.

Weak climatic control of stand-scale fire history during the late holocene.

PubMed

Gavin, Daniel G; Hu, Feng Sheng; Lertzman, Kenneth; Corbett, Peter

2006-07-01

Forest fire occurrence is affected by multiple controls that operate at local to regional scales. At the spatial scale of forest stands, regional climatic controls may be obscured by local controls (e.g., stochastic ignitions, topography, and fuel loads), but the long-term role of such local controls is poorly understood. We report here stand-scale (<100 ha) fire histories of the past 5000 years based on the analysis of sediment charcoal at two lakes 11 km apart in southeastern British Columbia. The two lakes are today located in similar subalpine forests, and they likely have experienced the same late-Holocene climatic changes because of their close proximity. We evaluated two independent properties of fire history: (1) fire-interval distribution, a measure of the overall incidence of fire, and (2) fire synchroneity, a measure of the co-occurrence of fire (here, assessed at centennial to millennial time scales due to the resolution of sediment records). Fire-interval distributions differed between the sites prior to, but not after, 2500 yr before present. When the entire 5000-yr period is considered, no statistical synchrony between fire-episode dates existed between the two sites at any temporal scale, but for the last 2500 yr marginal levels of synchrony occurred at centennial scales. Each individual fire record exhibited little coherency with regional climate changes. In contrast, variations in the composite record (average of both sites) matched variations in climate evidenced by late-Holocene glacial advances. This was probably due to the increased sample size and spatial extent represented by the composite record (up to 200 ha) plus increased regional climatic variability over the last several millennia, which may have partially overridden local, non-climatic controls. We conclude that (1) over past millennia, neighboring stands with similar modern conditions may have experienced different fire intervals and asynchronous patterns in fire episodes, likely because local controls outweighed the synchronizing effect of climate; (2) the influence of climate on fire occurrence is more strongly expressed when climatic variability is relatively great; and (3) multiple records from a region are essential if climate-fire relations are to be reliably described.

Climate and Fuel Controls on North American Paleofires: Smoldering to Flaming in the Late-Glacial-Holocene Transition

NASA Technical Reports Server (NTRS)

Han, Y. M.; Peteet, D. M.; Arimoto, R.; Cao, J. J.; An, Z. S.; Sritrairat, S.; Yan, B. Z.

2016-01-01

Smoldering and flaming fires, which emit different proportions of organic (OC) and black carbon (BC, in the form of char and soot), have long been recognized in modern wildfire observations but never in a paleo-record, and little is known about their interactions with climate. Here we show that in the late glacial-early Holocene transition period, when the climate was moist, relatively high quantities of char were deposited in Linsley Pond, Connecticut, USA while soot was more abundant during the warmer and drier early Holocene interval. The highest soot mass accumulation rates (MARs) occurred at the beginning of the Holocene as fuel availability increased through the climatic transition when boreal forests were locally extirpated. These variations with time are related to the different formation pathways of char and soot, which are governed by combustion efficiency. This study provides an approach for differentiating smoldering from flaming combustion in paleo-wildfire reconstructions. Our results suggest that climate and fuel loads control the occurrence of different wildfire types and precipitation may play a key role.

Climate and Fuel Controls on North American Paleofires: Smoldering to Flaming in the Late-glacial-Holocene Transition

NASA Astrophysics Data System (ADS)

Han, Y. M.; Peteet, D. M.; Arimoto, R.; Cao, J. J.; An, Z. S.; Sritrairat, S.; Yan, B. Z.

2016-02-01

Smoldering and flaming fires, which emit different proportions of organic (OC) and black carbon (BC, in the form of char and soot), have long been recognized in modern wildfire observations but never in a paleo-record, and little is known about their interactions with climate. Here we show that in the late glacial-early Holocene transition period, when the climate was moist, relatively high quantities of char were deposited in Linsley Pond, Connecticut, USA while soot was more abundant during the warmer and drier early Holocene interval. The highest soot mass accumulation rates (MARs) occurred at the beginning of the Holocene as fuel availability increased through the climatic transition when boreal forests were locally extirpated. These variations with time are related to the different formation pathways of char and soot, which are governed by combustion efficiency. This study provides an approach for differentiating smoldering from flaming combustion in paleo-wildfire reconstructions. Our results suggest that climate and fuel loads control the occurrence of different wildfire types and precipitation may play a key role.

Climate and Fuel Controls on North American Paleofires: Smoldering to Flaming in the Late-glacial-Holocene Transition.

PubMed

Han, Y M; Peteet, D M; Arimoto, R; Cao, J J; An, Z S; Sritrairat, S; Yan, B Z

2016-02-10

Smoldering and flaming fires, which emit different proportions of organic (OC) and black carbon (BC, in the form of char and soot), have long been recognized in modern wildfire observations but never in a paleo-record, and little is known about their interactions with climate. Here we show that in the late glacial-early Holocene transition period, when the climate was moist, relatively high quantities of char were deposited in Linsley Pond, Connecticut, USA while soot was more abundant during the warmer and drier early Holocene interval. The highest soot mass accumulation rates (MARs) occurred at the beginning of the Holocene as fuel availability increased through the climatic transition when boreal forests were locally extirpated. These variations with time are related to the different formation pathways of char and soot, which are governed by combustion efficiency. This study provides an approach for differentiating smoldering from flaming combustion in paleo-wildfire reconstructions. Our results suggest that climate and fuel loads control the occurrence of different wildfire types and precipitation may play a key role.

Work organization and health among immigrant women: Latina manual workers in North Carolina.

PubMed

Arcury, Thomas A; Grzywacz, Joseph G; Chen, Haiying; Mora, Dana C; Quandt, Sara A

2014-12-01

We sought to describe work organization attributes for employed immigrant Latinas and determine associations of work organization with physical health, mental health, and health-related quality of life. We conducted a cross-sectional survey with 319 employed Latinas in western North Carolina (2009-2011). Measures included job demands (heavy load, awkward posture, psychological demand), decision latitude (skill variety, job control), support (supervisor control, safety climate), musculoskeletal symptoms, mental health (depressive symptoms), and mental (MCS) and physical component score (PCS) health-related quality of life. Three fifths reported musculoskeletal symptoms. Mean scores for depression, MCS, and PCS were 6.2 (SE = 0.2), 38.3 (SE = 0.5), and 42.8 (SE = 0.3), respectively. Greater job demands (heavy load, awkward posture, greater psychological demand) were associated with more musculoskeletal and depressive symptoms and worse MCS. Less decision latitude (lower skill variety, job control) was associated with more musculoskeletal and depressive symptoms. Greater support (supervisor's power and safety climate) was associated with fewer depressive symptoms and better MCS. Work organization should be considered to improve occupational health of vulnerable women workers. Additional research should delineate the links between work organization and health among vulnerable workers.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rice, C. Keith; Shen, Bo; Shrestha, Som S.

This report describes an analysis to investigate representative heating loads for single-family detached homes using current EnergyPlus simulations (DOE 2014a). Hourly delivered load results are used to determine binned load lines using US Department of Energy (DOE) residential prototype building models (DOE 2014b) developed by Pacific Northwest National Laboratory (PNNL). The selected residential single-family prototype buildings are based on the 2006 International Energy Conservation Code (IECC 2006) in the DOE climate regions. The resulting load lines are compared with the American National Standards Institute (ANSI)/Air-Conditioning, Heating, and Refrigeration Institute (AHRI) Standard 210/240 (AHRI 2008) minimum and maximum design heating requirementmore » (DHR) load lines of the heating seasonal performance factor (HSPF) ratings procedure for each region. The results indicate that a heating load line closer to the maximum DHR load line, and with a lower zero load ambient temperature, is more representative of heating loads predicted for EnergyPlus prototype residential buildings than the minimum DHR load line presently used to determine HSPF ratings. An alternative heating load line equation was developed and compared to binned load lines obtained from the EnergyPlus simulation results. The effect on HSPF of the alternative heating load line was evaluated for single-speed and two-capacity heat pumps, and an average HSPF reduction of 16% was found. The alternative heating load line relationship is tied to the rated cooling capacity of the heat pump based on EnergyPlus autosizing, which is more representative of the house load characteristics than the rated heating capacity. The alternative heating load line equation was found to be independent of climate for the six DOE climate regions investigated, provided an adjustable zero load ambient temperature is used. For Region IV, the default DOE climate region used for HSPF ratings, the higher load line results in an ~28% increase in delivered heating load and an ~52% increase in the estimated heating operating cost over that given in the AHRI directory (AHRI 2014).« less

Residential Variable-Capacity Heat Pumps Sized to Heating Loads

DOE Office of Scientific and Technical Information (OSTI.GOV)

Munk, Jeffrey D.; Jackson, Roderick K.; Odukomaiya, Adewale

2014-01-01

Variable capacity heat pumps are an emerging technology offering significant energy savings potential and improved efficiency. With conventional single-speed systems, it is important to appropriately size heat pumps for the cooling load as over-sizing would result in cycling and insufficient latent capacity required for humidity control. These appropriately sized systems are often under-sized for the heating load and require inefficient supplemental electric resistance heat to meet the heating demand. Variable capacity heat pumps address these shortcomings by providing an opportunity to intentionally size systems for the dominant heating season load without adverse effects of cycling or insufficient dehumidification in themore » cooling season. This intentionally-sized system could result in significant energy savings in the heating season, as the need for inefficient supplemental electric resistance heat is drastically reduced. This is a continuation of a study evaluating the energy consumption of variable capacity heat pumps installed in two unoccupied research homes in Farragut, a suburb of Knoxville, Tennessee. In this particular study, space conditioning systems are intentionally sized for the heating season loads to provide an opportunity to understand and evaluate the impact this would have on electric resistance heat use and dehumidification. The results and conclusions drawn through this research are valid and specific for portions of the Southeastern and Midwestern United States falling in the mixed-humid climate zone. While other regions in the U.S. do not experience this type of climate, this work provides a basis for, and can help understand the implications of other climate zones on residential space conditioning energy consumption. The data presented here will provide a framework for fine tuning residential building EnergyPlus models that are being developed.« less

Climate Variability Impacts on Watershed Nutrient Delivery and Reservoir Production

NASA Astrophysics Data System (ADS)

White, J. D.; Prochnow, S. J.; Zygo, L. M.; Byars, B. W.

2005-05-01

Reservoirs in agricultural dominated watersheds tend to exhibit pulse-system behavior especially if located in climates dominated by summer convective precipitation inputs. Concentration and bulk mass of nutrient and sediment inputs into reservoir systems vary in terms of timing and magnitude of delivery from watershed sources to reservoirs under these climate conditions. Reservoir management often focuses on long-term average inputs without considering short and long-term impacts of variation in loading. In this study we modeled a watershed-reservoir system to assess how climate variability affects reservoir primary production through shifts in external loading and internal recycling of limiting nutrients. The Bosque watershed encompasses 423,824 ha in central Texas which delivers water to Lake Waco, a 2900 ha reservoir that is the primary water source for the city of Waco and surrounding areas. Utilizing the Soil Water Assessment Tool for the watershed and river simulations and the CE-Qual-2e model for the reservoir, hydrologic and nutrient dynamics were simulated for a 10 year period encompassing two ENSO cycles. The models were calibrated based on point measurement of water quality attributes for a two year time period. Results indicated that watershed delivery of nutrients was affected by the presence and density of small flood-control structure in the watershed. However, considerable nitrogen and phosphorus loadings were derived from soils in the upper watershed which have had long-term waste-application from concentrated animal feeding operations. During El Niño years, nutrient and sediment loads increased by 3 times above non-El Niño years. The simulated response within the reservoir to these nutrient and sediment loads had both direct and indirect. Productivity evaluated from chlorophyll a and algal biomass increased under El Niño conditions, however species composition shifts were found with an increase in cyanobacteria dominance. In non-El Niño years, species composition was more evenly distributed. At the longer time scale, El Niño events with accompanying increase in nutrient loads were followed by years in which productivity declined below levels predicted solely by nutrient ratios. This was due to subtle shifts in organic matter decomposition where productive years are followed by increases in refractory material which sequesters nutrients and reduces internal loading.

Sleeper Cab Climate Control Load Reduction for Long-Haul Truck Rest Period Idling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lustbader, J. A.; Kreutzer, C.; Adelman, S.

2015-04-29

Annual fuel use for long-haul truck rest period idling is estimated at 667 million gallons in the United States. The U.S. Department of Energy’s National Renewable Energy Laboratory’s CoolCab project aims to reduce heating, ventilating, and air conditioning (HVAC) loads and resulting fuel use from rest period idling by working closely with industry to design efficient long-haul truck climate control systems while maintaining occupant comfort. Enhancing the thermal performance of cab/sleepers will enable smaller, lighter, and more cost-effective idle reduction solutions. In order for candidate idle reduction technologies to be implemented at the original equipment manufacturer and fleet level, theirmore » effectiveness must be quantified. To address this need, a number of promising candidate technologies were evaluated through experimentation and modeling to determine their effectiveness in reducing rest period HVAC loads. For this study, load reduction strategies were grouped into the focus areas of solar envelope, occupant environment, and conductive pathways. The technologies selected for a complete-cab package of technologies were “ultra-white” paint, advanced insulation, and advanced curtains. To measure the impact of these technologies, a nationally-averaged solar-weighted reflectivity long-haul truck paint color was determined and applied to the baseline test vehicle. Using the complete-cab package of technologies, electrical energy consumption for long-haul truck daytime rest period air conditioning was reduced by at least 35% for summer weather conditions in Colorado. The National Renewable Energy Laboratory's CoolCalc model was then used to extrapolate the performance of the thermal load reduction technologies nationally for 161 major U.S. cities using typical weather conditions for each location over an entire year.« less

A spatially distributed model for assessment of the effects of changing land use and climate on urban stream quality: Development of a Spatially Distributed Urban Water Quality Model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun, Ning; Yearsley, John; Baptiste, Marisa

While the effects of land use change in urban areas have been widely examined, the combined effects of climate and land use change on the quality of urban and urbanizing streams have received much less attention. We describe a modeling framework that is applicable to the evaluation of potential changes in urban water quality and associated hydrologic changes in response to ongoing climate and landscape alteration. The grid-based spatially distributed model, DHSVM-WQ, is an outgrowth of the Distributed Hydrology-Soil-Vegetation Model (DHSVM) that incorporates modules for assessing hydrology and water quality in urbanized watersheds at a high spatial and temporal resolution.more » DHSVM-WQ simulates surface runoff quality and in-stream processes that control the transport of nonpoint-source (NPS) pollutants into urban streams. We configure DHSVM-WQ for three partially urbanized catchments in the Puget Sound region to evaluate the water quality responses to current conditions and projected changes in climate and/or land use over the next century. Here we focus on total suspended solids (TSS) and total phosphorus (TP) from nonpoint sources (runoff), as well as stream temperature. The projection of future land use is characterized by a combination of densification in existing urban or partially urban areas, and expansion of the urban footprint. The climate change scenarios consist of individual and concurrent changes in temperature and precipitation. Future precipitation is projected to increase in winter and decrease in summer, while future temperature is projected to increase throughout the year. Our results show that urbanization has a much greater effect than climate change on both the magnitude and seasonal variability of streamflow, TSS and TP loads largely due to substantially increased streamflow, and particularly winter flow peaks. Water temperature is more sensitive to climate warming scenarios than to urbanization and precipitation changes. Future urbanization and climate change together are predicted to significantly increase annual mean streamflow (up to 55%), water temperature (up to 1.9 ºC), TSS load (up to 182%), and TP load (up to 74%).« less

The effects of climate change on heating energy consumption of office buildings in different climate zones in China

NASA Astrophysics Data System (ADS)

Meng, Fanchao; Li, Mingcai; Cao, Jingfu; Li, Ji; Xiong, Mingming; Feng, Xiaomei; Ren, Guoyu

2017-06-01

Climate plays an important role in heating energy consumption owing to the direct relationship between space heating and changes in meteorological conditions. To quantify the impact, the Transient System Simulation Program software was used to simulate the heating loads of office buildings in Harbin, Tianjin, and Shanghai, representing three major climate zones (i.e., severe cold, cold, and hot summer and cold winter climate zones) in China during 1961-2010. Stepwise multiple linear regression was performed to determine the key climatic parameters influencing heating energy consumption. The results showed that dry bulb temperature (DBT) is the dominant climatic parameter affecting building heating loads in all three climate zones across China during the heating period at daily, monthly, and yearly scales (R 2 ≥ 0.86). With the continuous warming climate in winter over the past 50 years, heating loads decreased by 14.2, 7.2, and 7.1 W/m2 in Harbin, Tianjin, and Shanghai, respectively, indicating that the decreasing rate is more apparent in severe cold climate zone. When the DBT increases by 1 °C, the heating loads decrease by 253.1 W/m2 in Harbin, 177.2 W/m2 in Tianjin, and 126.4 W/m2 in Shanghai. These results suggest that the heating energy consumption can be well predicted by the regression models at different temporal scales in different climate conditions owing to the high determination coefficients. In addition, a greater decrease in heating energy consumption in northern severe cold and cold climate zones may efficiently promote the energy saving in these areas with high energy consumption for heating. Particularly, the likely future increase in temperatures should be considered in improving building energy efficiency.

WEPPCAT: An Online tool for assessing and managing the potential impacts of climate change on sediment loading to streams using the Water Erosion Prediction Project (WEPP) Model

EPA Science Inventory

WEPPCAT is an on-line tool that provides a flexible capability for creating user-determined climate change scenarios for assessing the potential impacts of climate change on sediment loading to streams using the USDA’s Water Erosion Prediction Project (WEPP) Model. In combination...

Fluvial response to climate variations and anthropogenic perturbations for the Ebro River, Spain in the last 4,000 years.

PubMed

Xing, Fei; Kettner, Albert J; Ashton, Andrew; Giosan, Liviu; Ibáñez, Carles; Kaplan, Jed O

2014-03-01

Fluvial sediment discharge can vary in response to climate changes and human activities, which in return influences human settlements and ecosystems through coastline progradation and retreat. To understand the mechanisms controlling the variations of fluvial water and sediment discharge for the Ebro drainage basin, Spain, we apply a hydrological model HydroTrend. Comparison of model results with a 47-year observational record (AD 1953-1999) suggests that the model adequately captures annual average water discharge (simulated 408 m(3)s(-1) versus observed 425 m(3)s(-1)) and sediment load (simulated 0.3 Mt yr(-1) versus observed 0.28 ± 0.04 Mt yr(-1)) for the Ebro basin. A long-term (4000-year) simulation, driven by paleoclimate and anthropogenic land cover change scenarios, indicates that water discharge is controlled by the changes in precipitation, which has a high annual variability but no long-term trend. Modeled suspended sediment load, however, has an increasing trend over time, which is closely related to anthropogenic land cover variations with no significant correlation to climatic changes. The simulation suggests that 4,000 years ago the annual sediment load to the ocean was 30.5 Mt yr(-1), which increased over time to 47.2 Mt yr(-1) (AD 1860-1960). In the second half of the 20th century, the emplacement of large dams resulted in a dramatic decrease in suspended sediment discharge, eventually reducing the flux to the ocean by more than 99% (mean value changes from 38.1 Mt yr(-1) to 0.3 Mt yr(-1)). Copyright © 2013 Elsevier B.V. All rights reserved.

Building and environmental factors that influence bacterial and fungal loading on air conditioning cooling coils.

PubMed

Bakker, A; Siegel, J A; Mendell, M J; Peccia, J

2018-05-30

We investigated bacterial and fungal concentrations on cooling coils of commercial AC units and quantified associations between microbial loads and AC unit or building operational parameters. A field campaign was conducted to sample 25 AC units in the humid, subtropical climate of Southern CT, USA and 15 AC units in the hot-summer Mediterranean climate of Sacramento, CA, USA. Median concentrations (with interquartile range) of bacteria and fungi on the cooling coils were 1.2 × 10 7 (5.1 × 10 6 -3.9 × 10 7 ) cells/m 2 and 7.6 × 10 5 (5.6 × 10 4 -4.4 × 10 6 ) spore equivalents (SE)/m 2 , respectively. Concentrations varied among units with median unit concentrations ranging three orders of magnitude for bacteria and seven orders of magnitude for fungi. Controlled comparisons and multivariable regressions indicate that dominant factors associated with AC coil loading include the nominal efficiency of upstream filters (P = .008 for bacteria and P < .001 for fungi) and coil moisture, which was reflected in fungal loading differences between top and bottom halves of the AC coils in Southern CT (P = .05) and the dew points of the two climates considered (P = .04). Environmental and building characteristics explained 42% (P < .001) of bacterial concentration variability and 66% (P < .001) of fungal concentration variability among samples. © 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Energy-Efficient Management of Mechanical Ventilation and Relative Humidity in Hot-Humid Climates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Withers, Jr., Charles R.

2016-12-01

In hot and humid climates, it is challenging to energy-efficiently maintain indoor RH at acceptable levels while simultaneously providing required ventilation, particularly in high performance low cooling load homes. The fundamental problem with solely relying on fixed capacity central cooling systems to manage moisture during low sensible load periods is that they are oversized for cooler periods of the year despite being 'properly sized' for a very hot design cooling day. The primary goals of this project were to determine the impact of supplementing a central space conditioning system with 1) a supplemental dehumidifier and 2) a ductless mini-split onmore » seasonal energy use and summer peak power use as well as the impact on thermal distribution and humidity control inside a completely furnished lab home that was continuously ventilated in accordance with ASHRAE 62.2-2013.« less

Building America Case Study: Energy Efficient Management of Mechanical Ventilation and Relative Humidity in Hot-Humid Climates, Cocoa, Florida

DOE Office of Scientific and Technical Information (OSTI.GOV)

2017-01-01

In hot and humid climates, it is challenging to energy-efficiently maintain indoor RH at acceptable levels while simultaneously providing required ventilation, particularly in high performance low cooling load homes. The fundamental problem with solely relying on fixed capacity central cooling systems to manage moisture during low sensible load periods is that they are oversized for cooler periods of the year despite being 'properly sized' for a very hot design cooling day. The primary goals of this project were to determine the impact of supplementing a central space conditioning system with 1) a supplemental dehumidifier and 2) a ductless mini-split onmore » seasonal energy use and summer peak power use as well as the impact on thermal distribution and humidity control inside a completely furnished lab home that was continuously ventilated in accordance with ASHRAE 62.2-2013.« less

Personal cooling in hot workings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tuck, M.A.

1999-07-01

The number of mines experiencing climatic difficulties worldwide is increasing. In a large number of cases these climatic difficulties are confined to working areas only or to specific locations within working areas. Thus the problem in these mines can be described as highly localized, due to a large extent not to high rock temperatures but due to machine heat loads and low airflow rates. Under such situations conventional means of controlling the climate can be inapplicable and/or uneconomic. One possible means of achieving the required level of climatic control, to ensure worker health and safety whilst achieving economic gains, ismore » to adopt a system of active man cooling. This is the reverse of normal control techniques where the cooling power of the ventilating air is enhanced in some way. Current methods of active man cooling include ice jackets and various umbilical cord type systems. These have numerous drawbacks, such as limited useful exposure times and limitations to worker mobility. The paper suggests an alternative method of active man cooling than those currently available and reviews the design criteria for such a garment. The range of application of such a garment is discussed, under both normal and emergency situations.« less

Assessment of spatiotemporal variations in the fluvial wash-load component in the 21st century with regard to GCM climate change scenarios.

PubMed

Mouri, Goro

2015-11-15

For stream water, in which a relationship exists between wash-load concentration and discharge, an estimate of fine-sediment delivery may be obtained from a traditional fluvial wash-load rating curve. Here, we demonstrate that the remaining wash-load material load can be estimated from a traditional empirical principle on a nationwide scale. The traditional technique was applied to stream water for the whole of Japan. Four typical GCMs were selected from the Coupled Model Intercomparison Project Phase 5 (CMIP5) ensemble to provide the driving fields for the following regional climate models to assess the wash-load component based on rating curves: the Model for Interdisciplinary Research on Climate (MIROC), the Meteorological Research Institute Atmospheric General Circulation Model (MRI-GCM), the Hadley Centre Global Environment Model (HadGEM) and the Geophysical Fluid Dynamics Laboratory (GFDL) climate model. The simulations consisted of an ensemble, including multiple physics configurations and different Representative Concentration Pathways (RCP2.6, RCP4.5 and RCP8.5), which was used to produce monthly datasets for the whole country of Japan. The impacts of future climate changes on fluvial wash load in Japanese stream water were based on the balance of changes in hydrological factors. The annual and seasonal variations of the fluvial wash load were assessed from the result of the ensemble analysis in consideration of the Greenhouse Gas (GHG) emission scenarios. The determined results for the amount of wash load increase range from approximately 20 to 110% in the 2040s, especially along part of the Pacific Ocean and the Sea of Japan regions. In the 2090s, the amount of wash load is projected to increase by more than 50% over the whole of Japan. The assessment indicates that seasonal variation is particularly important because the rainy and typhoon seasons, which include extreme events, are the dominant seasons. Because fluvial wash-load-component turbidity appears to vary exponentially, this phenomenon has an impact on the management of social capital, such as drinking water services. Prediction of the impacts of future climate change on fluvial wash-load sediment is crucial for effective environmental planning and the management of social capital to adapt to the next century. We demonstrate that simulations comprise an ensemble of factors, including multiple physical configurations, associated with the wash-load component for the whole of Japan. Copyright © 2015 Elsevier B.V. All rights reserved.

Predicting response of fuel load to future changes in climate and atmospheric composition in the Southern United States.

Treesearch

Chi Zhang; Hanqin Tian; Yuhang Wang; Tao Zeng; Yongqiang Liu

2010-01-01

The model projected ecosystem carbon dynamics were incorporated into the default (contemporary) fuel load map developed by FCCS (Fuel Characteristic Classification System) to estimate the dynamics of fuel load in the Southern United States in response to projected changes in climate and atmosphere (CO2 and nitrogen deposition) from 2002 to 2050. The study results...

Pathogenic marine microbes influence the effects of climate change on a commercially important tropical bivalve.

PubMed

Turner, Lucy M; Alsterberg, Christian; Turner, Andrew D; Girisha, S K; Rai, Ashwin; Havenhand, Jonathan N; Venugopal, M N; Karunasagar, Indrani; Godhe, Anna

2016-08-31

There is growing evidence that climate change will increase the prevalence of toxic algae and harmful bacteria, which can accumulate in marine bivalves. However, we know little about any possible interactions between exposure to these microorganisms and the effects of climate change on bivalve health, or about how this may affect the bivalve toxin-pathogen load. In mesocosm experiments, mussels, Perna viridis, were subjected to simulated climate change (warming and/or hyposalinity) and exposed to harmful bacteria and/or toxin-producing dinoflagellates. We found significant interactions between climate change and these microbes on metabolic and/or immunobiological function and toxin-pathogen load in mussels. Surprisingly, however, these effects were virtually eliminated when mussels were exposed to both harmful microorganisms simultaneously. This study is the first to examine the effects of climate change on determining mussel toxin-pathogen load in an ecologically relevant, multi-trophic context. The results may have considerable implications for seafood safety.

Efficient operation scheduling for adsorption chillers using predictive optimization-based control methods

NASA Astrophysics Data System (ADS)

Bürger, Adrian; Sawant, Parantapa; Bohlayer, Markus; Altmann-Dieses, Angelika; Braun, Marco; Diehl, Moritz

2017-10-01

Within this work, the benefits of using predictive control methods for the operation of Adsorption Cooling Machines (ACMs) are shown on a simulation study. Since the internal control decisions of series-manufactured ACMs often cannot be influenced, the work focuses on optimized scheduling of an ACM considering its internal functioning as well as forecasts for load and driving energy occurrence. For illustration, an assumed solar thermal climate system is introduced and a system model suitable for use within gradient-based optimization methods is developed. The results of a system simulation using a conventional scheme for ACM scheduling are compared to the results of a predictive, optimization-based scheduling approach for the same exemplary scenario of load and driving energy occurrence. The benefits of the latter approach are shown and future actions for application of these methods for system control are addressed.

Changing climate and nutrient transfers: Evidence from high temporal resolution concentration-flow dynamics in headwater catchments.

PubMed

Ockenden, M C; Deasy, C E; Benskin, C McW H; Beven, K J; Burke, S; Collins, A L; Evans, R; Falloon, P D; Forber, K J; Hiscock, K M; Hollaway, M J; Kahana, R; Macleod, C J A; Reaney, S M; Snell, M A; Villamizar, M L; Wearing, C; Withers, P J A; Zhou, J G; Haygarth, P M

2016-04-01

We hypothesise that climate change, together with intensive agricultural systems, will increase the transfer of pollutants from land to water and impact on stream health. This study builds, for the first time, an integrated assessment of nutrient transfers, bringing together a) high-frequency data from the outlets of two surface water-dominated, headwater (~10km(2)) agricultural catchments, b) event-by-event analysis of nutrient transfers, c) concentration duration curves for comparison with EU Water Framework Directive water quality targets, d) event analysis of location-specific, sub-daily rainfall projections (UKCP, 2009), and e) a linear model relating storm rainfall to phosphorus load. These components, in combination, bring innovation and new insight into the estimation of future phosphorus transfers, which was not available from individual components. The data demonstrated two features of particular concern for climate change impacts. Firstly, the bulk of the suspended sediment and total phosphorus (TP) load (greater than 90% and 80% respectively) was transferred during the highest discharge events. The linear model of rainfall-driven TP transfers estimated that, with the projected increase in winter rainfall (+8% to +17% in the catchments by 2050s), annual event loads might increase by around 9% on average, if agricultural practices remain unchanged. Secondly, events following dry periods of several weeks, particularly in summer, were responsible for high concentrations of phosphorus, but relatively low loads. The high concentrations, associated with low flow, could become more frequent or last longer in the future, with a corresponding increase in the length of time that threshold concentrations (e.g. for water quality status) are exceeded. The results suggest that in order to build resilience in stream health and help mitigate potential increases in diffuse agricultural water pollution due to climate change, land management practices should target controllable risk factors, such as soil nutrient status, soil condition and crop cover. Copyright © 2015 Elsevier B.V. All rights reserved.

Impact of Climate Variability and Landscape Patterns on Water Budget and Nutrient Loads in a Peri-urban Watershed: A Coupled Analysis Using Process-based Hydrological Model and Landscape Indices.

PubMed

Li, Chongwei; Zhang, Yajuan; Kharel, Gehendra; Zou, Chris B

2018-06-01

Nutrient discharge into peri-urban streams and reservoirs constitutes a significant pressure on environmental management, but quantitative assessment of non-point source pollution under climate variability in fast changing peri-urban watersheds is challenging. Soil and Water Assessment Tool (SWAT) was used to simulate water budget and nutrient loads for landscape patterns representing a 30-year progression of urbanization in a peri-urban watershed near Tianjin metropolis, China. A suite of landscape pattern indices was related to nitrogen (N) and phosphorous (P) loads under dry and wet climate using CANOCO redundancy analysis. The calibrated SWAT model was adequate to simulate runoff and nutrient loads for this peri-urban watershed, with Nash-Sutcliffe coefficient (NSE) and coefficient of determination (R 2 ) > 0.70 and percentage bias (PBIAS) between -7 and +18 for calibration and validation periods. With the progression of urbanization, forest remained the main "sink" landscape while cultivated and urban lands remained the main "source" landscapes with the role of orchard and grassland being uncertain and changing with time. Compared to 1984, the landscape use pattern in 2013 increased nutrient discharge by 10%. Nutrient loads modelled under wet climate were 3-4 times higher than that under dry climate for the same landscape pattern. Results indicate that climate change could impose a far greater impact on runoff and nutrient discharge in a peri-urban watershed than landscape pattern change.

Impact of Climate Variability and Landscape Patterns on Water Budget and Nutrient Loads in a Peri-urban Watershed: A Coupled Analysis Using Process-based Hydrological Model and Landscape Indices

NASA Astrophysics Data System (ADS)

Li, Chongwei; Zhang, Yajuan; Kharel, Gehendra; Zou, Chris B.

2018-06-01

Nutrient discharge into peri-urban streams and reservoirs constitutes a significant pressure on environmental management, but quantitative assessment of non-point source pollution under climate variability in fast changing peri-urban watersheds is challenging. Soil and Water Assessment Tool (SWAT) was used to simulate water budget and nutrient loads for landscape patterns representing a 30-year progression of urbanization in a peri-urban watershed near Tianjin metropolis, China. A suite of landscape pattern indices was related to nitrogen (N) and phosphorous (P) loads under dry and wet climate using CANOCO redundancy analysis. The calibrated SWAT model was adequate to simulate runoff and nutrient loads for this peri-urban watershed, with Nash-Sutcliffe coefficient (NSE) and coefficient of determination ( R 2) > 0.70 and percentage bias (PBIAS) between -7 and +18 for calibration and validation periods. With the progression of urbanization, forest remained the main "sink" landscape while cultivated and urban lands remained the main "source" landscapes with the role of orchard and grassland being uncertain and changing with time. Compared to 1984, the landscape use pattern in 2013 increased nutrient discharge by 10%. Nutrient loads modelled under wet climate were 3-4 times higher than that under dry climate for the same landscape pattern. Results indicate that climate change could impose a far greater impact on runoff and nutrient discharge in a peri-urban watershed than landscape pattern change.

The contribution of ice cover to sediment resuspension in a shallow temperate lake: possible effects of climate change on internal nutrient loading.

PubMed

Niemistö, Juha P; Horppila, Jukka

2007-01-01

The effect of ice cover on sediment resuspension and internal total P (Tot-P) loading was studied in the northern temperate Kirkkojärvi basin in Finland. The gross sedimentation and resuspension rates were estimated with sediment traps during ice-cover and ice-free periods. After ice break, the average gross sedimentation rate increased from 1.4 to 30.0 g dw m(-2) d(-1). Resuspension calculations showed clearly higher values after ice break as well. Under ice cover, resuspension ranged from 50 to 78% of the gross sedimentation while during the ice-free period it constituted from 87 to 97% of the gross sedimentation. Consequently, the average resuspension rate increased from 1.0 g dw m(-2) d(-1) under ice-cover to 27.0 g dw m(-2) d(-1) after thaw, indicating the strong effect of ice cover on sediment resuspension. To estimate the potential effect of climate change on internal P loading caused by resuspension we compared the Tot-P loading calculations between the present climate and the climate with doubled atmospheric CO2 concentration relative to the present day values (ice cover reduced from current 165 to 105 d). The annual load increased from 7.4 to 9.4 g m(-2). In conclusion, the annual internal Tot-P loading caused by resuspension will increase by 28% in the Kirkkojärvi basin if the 2xCO2 climate scenario comes true.

Climate change and wetland loss impacts on a Western river's water quality

NASA Astrophysics Data System (ADS)

Records, R. M.; Arabi, M.; Fassnacht, S. R.; Duffy, W. G.; Ahmadi, M.; Hegewisch, K. C.

2014-05-01

An understanding of potential stream water quality conditions under future climate is critical for the sustainability of ecosystems and protection of human health. Changes in wetland water balance under projected climate could alter wetland extent or cause wetland loss. This study assessed the potential climate-induced changes to in-stream sediment and nutrients loads in the historically snow melt-dominated Sprague River, Oregon, Western United States. Additionally, potential water quality impacts of combined changes in wetland water balance and wetland area under future climatic conditions were evaluated. The study utilized the Soil and Water Assessment Tool (SWAT) forced with statistical downscaling of general circulation model (GCM) data from the Coupled Model Intercomparison Project 5 (CMIP5) using the Multivariate Adaptive Constructed Analogs (MACA) method. Our findings suggest that in the Sprague River (1) mid-21st century nutrient and sediment loads could increase significantly during the high flow season under warmer-wetter climate projections, or could change only nominally in a warmer and somewhat drier future; (2) although water quality conditions under some future climate scenarios and no wetland loss may be similar to the past, the combined impact of climate change and wetland losses on nutrient loads could be large; (3) increases in stream total phosphorus (TP) concentration with wetland loss under future climate scenarios would be greatest at high-magnitude, low-probability flows; and (4) loss of riparian wetlands in both headwaters and lowlands could increase outlet TP loads to a similar degree, but this could be due to distinctly different mechanisms in different parts of the watershed.

Lower and lower Middle Pennsylvanian fluvial to estuarine deposition, central Appalachian basin: Effects of eustasy, tectonics, and climate

USGS Publications Warehouse

Greb, S.F.; Chesnut, D.R.

1996-01-01

Interpretations of Pennsylvanian sedimentation and peat accumulation commonly use examples from the Appalachian basin because of the excellent outcrops and large reserve of coal (>100 billion metric tons) in the region. Particularly controversial is the origin of Lower and lower Middle Pennsylvanian quartzose sandstones; beach-barrier, marine-bar, tidalstrait, and fluvial models all have been applied to a series of sand bodies along the western outcrop margin of the basin. Inter-pretations of these sandstones and their inferred lateral relationships are critical for understanding the relative degree of eustatic, tectonic, and climatic controls on Early Pennsylvanian sedimentation. Cross sections utilizing >1000 subsurface records and detailed sedimentological analysis of the Livingston Conglomerate, Rockcastle Sandstone, Corbin Sandstone, and Pine Creek sandstone (an informal member) of the Breathitt Group were used to show that each of the principal quartzose sandstones on the margin of the central Appalachian basin contains both fluvial and marginal marine facies. The four sandstones are fluvially dominated and are inferred to represent successive bed-load trunk systems of the Appalachian foreland. Base-level rise and an associated decrease in extra-basinal sediment at the end of each fluvial episode led to the development of local estuaries and marine reworking of the tops of the sand belts. Each of the sand belts is capped locally by a coal, regardless of whether the upper surfaces of the sand belts are of fluvial or estuarine origin, suggesting allocyclic controls on deposition. Peats were controlled by a tropical ever-wet climate, which also influenced sandstone composition through weathering of stored sands in slowly aggrading braidplains. Recurrent stacking of thick, coarse-grained, fluvial deposits with extra-basinal quartz pebbles; dominance of bed-load fluvial-lowstand deposits over mixed-load, estuarine-transgressive deposits; thinning of sand belts around tectonic highs and along faults; cratonward shift and amalgamation of successive sand belts on the margin of the basin; and truncation of successive sand belts toward the fault-bound margin of the basin are interpreted as regional responses to Alleghenian tectonism, inferred to have been the dominant control on accommodation space and sediment flux in the Early Pennsylvanian basin.

Control factors and scale analysis of annual river water, sediments and carbon transport in China.

PubMed

Song, Chunlin; Wang, Genxu; Sun, Xiangyang; Chang, Ruiying; Mao, Tianxu

2016-05-11

Under the context of dramatic human disturbances on river system, the processes that control the transport of water, sediment, and carbon from river basins to coastal seas are not completely understood. Here we performed a quantitative synthesis for 121 sites across China to find control factors of annual river exports (Rc: runoff coefficient; TSSC: total suspended sediment concentration; TSSL: total suspended sediment loads; TOCL: total organic carbon loads) at different spatial scales. The results indicated that human activities such as dam construction and vegetation restoration might have a greater influence than climate on the transport of river sediment and carbon, although climate was a major driver of Rc. Multiple spatial scale analyses indicated that Rc increased from the small to medium scale by 20% and then decreased at the sizable scale by 20%. TSSC decreased from the small to sizeable scale but increase from the sizeable to large scales; however, TSSL significantly decreased from small (768 g·m(-2)·a(-1)) to medium spatial scale basins (258 g·m(-2)·a(-1)), and TOCL decreased from the medium to large scale. Our results will improve the understanding of water, sediment and carbon transport processes and contribute better water and land resources management strategies from different spatial scales.

Climate variability and extremes, interacting with nitrogen storage, amplify eutrophication risk

USGS Publications Warehouse

Lee, Minjin; Shevliakova, Elena; Malyshev, Sergey; Milly, P.C.D.; Jaffe, Peter R.

2016-01-01

Despite 30 years of basin-wide nutrient-reduction efforts, severe hypoxia continues to be observed in the Chesapeake Bay. Here we demonstrate the critical influence of climate variability, interacting with accumulated nitrogen (N) over multidecades, on Susquehanna River dissolved nitrogen (DN) loads, known precursors of the hypoxia in the Bay. We used the process model LM3-TAN (Terrestrial and Aquatic Nitrogen), which is capable of capturing both seasonal and decadal-to-century changes in vegetation-soil-river N storage, and produced nine scenarios of DN-load distributions under different short-term scenarios of climate variability and extremes. We illustrate that after 1 to 3 yearlong dry spells, the likelihood of exceeding a threshold DN load (56 kt yr−1) increases by 40 to 65% due to flushing of N accumulated throughout the dry spells and altered microbial processes. Our analyses suggest that possible future increases in climate variability/extremes—specifically, high precipitation occurring after multiyear dry spells—could likely lead to high DN-load anomalies and hypoxia.

Simulated impacts of climate change on phosphorus loading to Lake Michigan

USGS Publications Warehouse

Robertson, Dale M.; Saad, David A.; Christiansen, Daniel E.; Lorenz, David J

2016-01-01

Phosphorus (P) loading to the Great Lakes has caused various types of eutrophication problems. Future climatic changes may modify this loading because climatic models project changes in future meteorological conditions, especially for the key hydrologic driver — precipitation. Therefore, the goal of this study is to project how P loading may change from the range of projected climatic changes. To project the future response in P loading, the HydroSPARROW approach was developed that links results from two spatially explicit models, the SPAtially Referenced Regression on Watershed attributes (SPARROW) transport and fate watershed model and the water-quantity Precipitation Runoff Modeling System (PRMS). PRMS was used to project changes in streamflow throughout the Lake Michigan Basin using downscaled meteorological data from eight General Circulation Models (GCMs) subjected to three greenhouse gas emission scenarios. Downscaled GCMs project a + 2.1 to + 4.0 °C change in average-annual air temperature (+ 2.6 °C average) and a − 5.1% to + 16.7% change in total annual precipitation (+ 5.1% average) for this geographic area by the middle of this century (2045–2065) and larger changes by the end of the century. The climatic changes by mid-century are projected to result in a − 21.2% to + 8.9% change in total annual streamflow (− 1.8% average) and a − 29.6% to + 17.2% change in total annual P loading (− 3.1% average). Although the average projected changes in streamflow and P loading are relatively small for the entire basin, considerable variability exists spatially and among GCMs because of their variability in projected future precipitation.

Risk Assessment of Heating, Ventilating, and Air-Conditioning Strategies in Low-Load Homes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Poerschke, Andrew

2016-02-17

"Modern, energy efficient homes conforming to the Zero Energy Ready Home standard face the challenge of meeting high customer expectations for comfort. Traditional heating, ventilation, and air conditioning (HVAC) sizing and control strategies may be insufficient to adequately condition each zone due to unique load patterns in each room caused by a number of factors. These factors include solar heat gains, occupant-related gains, and gains associated with appliances and electronics. Because of shrinking shell loads, these intermittent factors are having an increasingly significant impact on the thermal load in each zone. Consequently, occupant comfort can be compromised. To evaluate themore » impact of climate and house geometry, as well as HVAC system and control strategies on comfort conditions, IBACOS analyzed the results of 99 TRNSYS multiple-zone simulations. The results of this analysis indicate that for simple-geometry and single-story plans, a single zone and thermostat can adequately condition the entire house. Demanding house geometry and houses with multiple stories require the consideration of multiple thermostats and multiple zones.« less

The Role of African Dust in Atlantic Climate During Heinrich Events

NASA Astrophysics Data System (ADS)

Murphy, L. N.; Goes, M.; Clement, A. C.

2017-11-01

Increased ice discharge in the North Atlantic is thought to cause a weakening, or collapse, of the Atlantic meridional overturning circulation (AMOC) during Heinrich events. Paleoclimate records indicate that these periods were marked by severe tropical aridity and dustiness. Although the driver of these events is still under debate, large freshwater input is necessary for climate models to simulate the magnitude, geographical extent, and abruptness of these events, indicating that they may be missing feedbacks. We hypothesize that the dust-climate feedback is one such feedback that has not been previously considered. Here we analyze the role of dust-climate feedbacks on the AMOC by parameterizing the dust radiative effects in an intermediate complexity model and consider uncertainties due to wind stress forcing and the magnitude of both atmospheric dust loading and freshwater hosing. We simulate both stable and unstable AMOC regimes by changing the prescribed wind stress forcing. In the unstable regime, additional dust loading during Heinrich events cools and freshens the North Atlantic and abruptly reduces the AMOC by 20% relative to a control simulation. In the stable regime, however, additional dust forcing alone does not alter the AMOC strength. Including both freshwater and dust forcing results in a cooling of the subtropical North Atlantic more comparable to proxy records than with freshwater forcing alone. We conclude that dust-climate feedbacks may provide amplification to Heinrich cooling by further weakening AMOC and increasing North Atlantic sea ice coverage.

Field Study of Performance, Comfort, and Sizing of Two Variable-Speed Heat Pumps Installed in a Single 2-Story Residence

DOE Office of Scientific and Technical Information (OSTI.GOV)

Munk, Jeffrey D; Odukomaiya, Adewale O; Gehl, Anthony C

2014-01-01

With the recent advancements in the application of variable-speed (VS) compressors to residential HVAC systems, opportunities are now available to size heat pumps (HPs) to more effectively meet heating and cooling loads in many of the climate zones in the US with limited use of inefficient resistance heat. This is in contrast to sizing guidance for traditional single-speed HPs that limits the ability to oversize with regard to cooling loads, because of risks of poor dehumidification during the cooling season and increased cycling losses. VS-drive HPs can often run at 30-40% of their rated cooling capacity to reduce cycling losses,more » and can adjust fan speed to provide better indoor humidity control. Detailed air-side performance data was collected on two VS-drive heat pumps installed in a single unoccupied research house in Knoxville, TN, a mixed-humid climate. One system provided space conditioning for the upstairs, while the other unit provided space conditioning for the downstairs. Occupancy was simulated by operating the lights, shower, appliances, other plug loads, etc. to simulate the sensible and latent loads imposed on the building space by internal electric loads and human occupants according to the Building America Research Benchmark (2008). The seasonal efficiency and energy use of the units are calculated. Annual energy use is compared to that of the single speed minimum efficiency HPs tested in the same house previously. Sizing of the units relative to the measured building load and manual J design load calculations is examined. The impact of the unit sizing with regards to indoor comfort is also evaluated.« less

Climate change and wetland loss impacts on a western river's water quality

NASA Astrophysics Data System (ADS)

Records, R. M.; Arabi, M.; Fassnacht, S. R.; Duffy, W. G.; Ahmadi, M.; Hegewisch, K. C.

2014-11-01

An understanding of potential stream water quality conditions under future climate is critical for the sustainability of ecosystems and the protection of human health. Changes in wetland water balance under projected climate could alter wetland extent or cause wetland loss (e.g., via increased evapotranspiration and lower growing season flows leading to reduced riparian wetland inundation) or altered land use patterns. This study assessed the potential climate-induced changes to in-stream sediment and nutrient loads in the snowmelt-dominated Sprague River, Oregon, western US. Additionally, potential water quality impacts of combined changes in wetland water balance and wetland area under future climatic conditions were evaluated. The study utilized the Soil and Water Assessment Tool (SWAT) forced with statistical downscaling of general circulation model (GCM) data from the Coupled Model Intercomparison Project 5 (CMIP5) using the Multivariate Adaptive Constructed Analogs (MACA) method. Our findings suggest that, in the Sprague River, (1) mid-21st century nutrient and sediment loads could increase significantly during the high-flow season under warmer, wetter climate projections or could change only nominally in a warmer and somewhat drier future; (2) although water quality conditions under some future climate scenarios and no wetland loss may be similar to the past, the combined impact of climate change and wetland losses on nutrient loads could be large; (3) increases in stream total phosphorus (TP) concentration with wetland loss under future climate scenarios would be greatest at high-magnitude, low-probability flows; and (4) loss of riparian wetlands in both headwaters and lowlands could increase outlet TP loads to a similar degree, but this could be due to distinctly different mechanisms in different parts of the watershed.

Future climate and land uses effects on flow and nutrient loads of a Mediterranean catchment in South Australia.

PubMed

Shrestha, Manoj K; Recknagel, Friedrich; Frizenschaf, Jacqueline; Meyer, Wayne

2017-07-15

Mediterranean catchments experience already high seasonal variability alternating between dry and wet periods, and are more vulnerable to future climate and land use changes. Quantification of catchment response under future changes is particularly crucial for better water resources management. This study assessed the combined effects of future climate and land use changes on water yield, total nitrogen (TN) and total phosphorus (TP) loads of the Mediterranean Onkaparinga catchment in South Australia by means of the eco-hydrological model SWAT. Six different global climate models (GCMs) under two representative concentration pathways (RCPs) and a hypothetical land use change were used for future simulations. The climate models suggested a high degree of uncertainty, varying seasonally, in both flow and nutrient loads; however, a decreasing trend was observed. Average monthly TN and TP load decreased up to -55% and -56% respectively and were found to be dependent on flow magnitude. The annual and seasonal water yield and nutrient loads may only slightly be affected by envisaged land uses, but significantly altered by intermediate and high emission scenarios, predominantly during the spring season. The combined scenarios indicated the possibility of declining flow in future but nutrient enrichment in summer months, originating mainly from the land use scenario, that may elevate the risk of algal blooms in downstream drinking water reservoir. Hence, careful planning of future water resources in a Mediterranean catchment requires the assessment of combined effects of multiple climate models and land use scenarios on both water quantity and quality. Copyright © 2017 Elsevier B.V. All rights reserved.

Climate change is projected to have severe impacts on the frequency and intensity of peak electricity demand across the United States.

PubMed

Auffhammer, Maximilian; Baylis, Patrick; Hausman, Catherine H

2017-02-21

It has been suggested that climate change impacts on the electric sector will account for the majority of global economic damages by the end of the current century and beyond [Rose S, et al. (2014) Understanding the Social Cost of Carbon: A Technical Assessment ]. The empirical literature has shown significant increases in climate-driven impacts on overall consumption, yet has not focused on the cost implications of the increased intensity and frequency of extreme events driving peak demand, which is the highest load observed in a period. We use comprehensive, high-frequency data at the level of load balancing authorities to parameterize the relationship between average or peak electricity demand and temperature for a major economy. Using statistical models, we analyze multiyear data from 166 load balancing authorities in the United States. We couple the estimated temperature response functions for total daily consumption and daily peak load with 18 downscaled global climate models (GCMs) to simulate climate change-driven impacts on both outcomes. We show moderate and heterogeneous changes in consumption, with an average increase of 2.8% by end of century. The results of our peak load simulations, however, suggest significant increases in the intensity and frequency of peak events throughout the United States, assuming today's technology and electricity market fundamentals. As the electricity grid is built to endure maximum load, our findings have significant implications for the construction of costly peak generating capacity, suggesting additional peak capacity costs of up to 180 billion dollars by the end of the century under business-as-usual.

The influence of reservoirs, climate, land use and hydrologic conditions on loads and chemical quality of dissolved organic carbon in the Colorado River

USGS Publications Warehouse

Miller, Matthew P.

2012-01-01

Longitudinal patterns in dissolved organic carbon (DOC) loads and chemical quality were identified in the Colorado River from the headwaters in the Rocky Mountains to the United States-Mexico border from 1994 to 2011. Watershed- and reach-scale climate, land use, river discharge and hydrologic modification conditions that contribute to patterns in DOC were also identified. Principal components analysis (PCA) identified site-specific precipitation and reach-scale discharge as being correlated with sites in the upper basin, where there were increases in DOC load from the upstream to downstream direction. In the lower basin, where DOC load decreased from upstream to downstream, sites were correlated with site-specific temperature and reach-scale population, urban land use and hydrologic modification. In the reaches containing Lakes Powell and Mead, the two largest reservoirs in the United States, DOC quantity decreased, terrestrially derived aromatic DOC was degraded and/or autochthonous less aromatic DOC was produced. Taken together, these results suggest that longitudinal patterns in the relatively unregulated upper basin are influenced by watershed inputs of water and DOC, whereas DOC patterns in the lower basin are reflective of a balance between watershed contribution of water and DOC to the river and loss of water and DOC due to hydrologic modification and/or biogeochemical processes. These findings suggest that alteration of constituent fluxes in rivers that are highly regulated may overshadow watershed processes that would control fluxes in comparable unregulated rivers. Further, these results provide a foundation for detailed assessments of factors controlling the transport and chemical quality of DOC in the Colorado River.

Concentrations and loads of suspended sediment and trace element pollutants in a small semi-arid urban tributary, San Francisco Bay, California.

PubMed

McKee, Lester J; Gilbreath, Alicia N

2015-08-01

Water-quality policy documents throughout the world often identify urban stormwater as a large and controllable impact to sensitive ecosystems, yet there is often limited data to characterize concentrations and loads especially for rare and more difficult to quantify pollutants. In response, concentrations of suspended sediments and silver, mercury and selenium including speciation, and other trace elements were measured in dry and wet weather stormwater flow from a 100% urban watershed near San Francisco. Suspended sediment concentrations ranged between 1.4 and 2700 mg/L and varied with storm intensity. Turbidity was shown to correlate strongly with suspended sediments and most trace elements and was used as a surrogate with regression to estimate concentrations during unsampled periods and to compute loads. Mean suspended sediment yield was 31.5 t/km(2)/year. Total mercury ranged between 1.4 and 150 ng/L and was, on average, 92% particulate, 0.9% methylated, and 1.2% acid labile. Total mercury yield averaged 5.7 μg/m(2)/year. Total selenium ranged between non-detect and 2.9 μg/L and, on average, the total load (0.027 μg/m(2)/year) was 61% transported in dissolved phase. Selenate (Se(VI)) was the dominant species. Silver concentrations ranged between non-detect and 0.11 μg/L. Concentrations and loads of other trace elements were also highly variable and were generally similar to other urban systems with the exceptions of Ag and As (seldom reported) and Cr and Zn which exhibited concentrations and loads in the upper range of those reported elsewhere. Consistent with the semi-arid climatic setting, >95% of suspended sediment, 94% of total Hg, and 85-95 % of all other trace element loads were transported during storm flows with the exception of selenium which showed an inverse relationship between concentration and flow. Treatment of loads is made more challenging in arid climate settings due to low proportions of annual loads and greater dissolved phase during low flow conditions. This dataset fills an important local data gap for highly urban watersheds of San Francisco Bay. The field and interpretative methods, the uniqueness of the analyte list, and resulting information have general applicability for managing pollutant concentrations and loads in urban watersheds in other parts of the world and may have particularly useful application in more arid climates.

Modeling drivers of phosphorus loads in Chesapeake Bay tributaries and inferences about long-term change

USGS Publications Warehouse

Ryberg, Karen R.; Blomquist, Joel; Sprague, Lori A.; Sekellick, Andrew J.; Keisman, Jennifer

2018-01-01

Causal attribution of changes in water quality often consists of correlation, qualitative reasoning, listing references to the work of others, or speculation. To better support statements of attribution for water-quality trends, structural equation modeling was used to model the causal factors of total phosphorus loads in the Chesapeake Bay watershed. By transforming, scaling, and standardizing variables, grouping similar sites, grouping some causal factors into latent variable models, and using methods that correct for assumption violations, we developed a structural equation model to show how causal factors interact to produce total phosphorus loads. Climate (in the form of annual total precipitation and the Palmer Hydrologic Drought Index) and anthropogenic inputs are the major drivers of total phosphorus load in the Chesapeake Bay watershed. Increasing runoff due to natural climate variability is offsetting purposeful management actions that are otherwise decreasing phosphorus loading; consequently, management actions may need to be reexamined to achieve target reductions in the face of climate variability.

Assessing response of sediment load variation to climate change and human activities with six different approaches.

PubMed

Zhao, Guangju; Mu, Xingmin; Jiao, Juying; Gao, Peng; Sun, Wenyi; Li, Erhui; Wei, Yanhong; Huang, Jiacong

2018-05-23

Understanding the relative contributions of climate change and human activities to variations in sediment load is of great importance for regional soil, and river basin management. Considerable studies have investigated spatial-temporal variation of sediment load within the Loess Plateau; however, contradictory findings exist among methods used. This study systematically reviewed six quantitative methods: simple linear regression, double mass curve, sediment identity factor analysis, dam-sedimentation based method, the Sediment Delivery Distributed (SEDD) model, and the Soil Water Assessment Tool (SWAT) model. The calculation procedures and merits for each method were systematically explained. A case study in the Huangfuchuan watershed on the northern Loess Plateau has been undertaken. The results showed that sediment load had been reduced by 70.5% during the changing period from 1990 to 2012 compared to that of the baseline period from 1955 to 1989. Human activities accounted for an average of 93.6 ± 4.1% of the total decline in sediment load, whereas climate change contributed 6.4 ± 4.1%. Five methods produced similar estimates, but the linear regression yielded relatively different results. The results of this study provide a good reference for assessing the effects of climate change and human activities on sediment load variation by using different methods. Copyright © 2018. Published by Elsevier B.V.

Climate Change Impacts on Peak Electricity Consumption: US vs. Europe.

NASA Astrophysics Data System (ADS)

Auffhammer, M.

2016-12-01

It has been suggested that climate change impacts on the electric sector will account for the majority of global economic damages by the end of the current century and beyond. This finding is at odds with the relatively modest increase in climate driven impacts on consumption. Comprehensive high frequency load balancing authority level data have not been used previously to parameterize the relationship between electric demand and temperature for any major economy. Using statistical models we analyze multi-year data from load balancing authorities in the United States of America and the European Union, which are responsible for more than 90% of the electricity delivered to residential, industrial, commercial and agricultural customers. We couple the estimated response functions between total daily consumption and daily peak load with an ensemble of downscaled GCMs from the CMIP5 archive to simulate climate change driven impacts on both outcomes. We show moderate and highly spatially heterogeneous changes in consumption. The results of our peak load simulations, however, suggest significant changes in the intensity and frequency of peak events throughout the United States and Europe. As the electricity grid is built to endure maximum load, which usually occurs on the hottest day of the year, our findings have significant implications for the construction of costly peak generating and transmission capacity.

Climate change is projected to have severe impacts on the frequency and intensity of peak electricity demand across the United States

PubMed Central

Auffhammer, Maximilian; Baylis, Patrick; Hausman, Catherine H.

2017-01-01

It has been suggested that climate change impacts on the electric sector will account for the majority of global economic damages by the end of the current century and beyond [Rose S, et al. (2014) Understanding the Social Cost of Carbon: A Technical Assessment]. The empirical literature has shown significant increases in climate-driven impacts on overall consumption, yet has not focused on the cost implications of the increased intensity and frequency of extreme events driving peak demand, which is the highest load observed in a period. We use comprehensive, high-frequency data at the level of load balancing authorities to parameterize the relationship between average or peak electricity demand and temperature for a major economy. Using statistical models, we analyze multiyear data from 166 load balancing authorities in the United States. We couple the estimated temperature response functions for total daily consumption and daily peak load with 18 downscaled global climate models (GCMs) to simulate climate change-driven impacts on both outcomes. We show moderate and heterogeneous changes in consumption, with an average increase of 2.8% by end of century. The results of our peak load simulations, however, suggest significant increases in the intensity and frequency of peak events throughout the United States, assuming today’s technology and electricity market fundamentals. As the electricity grid is built to endure maximum load, our findings have significant implications for the construction of costly peak generating capacity, suggesting additional peak capacity costs of up to 180 billion dollars by the end of the century under business-as-usual. PMID:28167756

A multi-paradigm framework to assess the impacts of climate change on end-use energy demand.

PubMed

Nateghi, Roshanak; Mukherjee, Sayanti

2017-01-01

Projecting the long-term trends in energy demand is an increasingly complex endeavor due to the uncertain emerging changes in factors such as climate and policy. The existing energy-economy paradigms used to characterize the long-term trends in the energy sector do not adequately account for climate variability and change. In this paper, we propose a multi-paradigm framework for estimating the climate sensitivity of end-use energy demand that can easily be integrated with the existing energy-economy models. To illustrate the applicability of our proposed framework, we used the energy demand and climate data in the state of Indiana to train a Bayesian predictive model. We then leveraged the end-use demand trends as well as downscaled future climate scenarios to generate probabilistic estimates of the future end-use demand for space cooling, space heating and water heating, at the individual household and building level, in the residential and commercial sectors. Our results indicated that the residential load is much more sensitive to climate variability and change than the commercial load. Moreover, since the largest fraction of the residential energy demand in Indiana is attributed to heating, future warming scenarios could lead to reduced end-use demand due to lower space heating and water heating needs. In the commercial sector, the overall energy demand is expected to increase under the future warming scenarios. This is because the increased cooling load during hotter summer months will likely outpace the reduced heating load during the more temperate winter months.

A multi-paradigm framework to assess the impacts of climate change on end-use energy demand

PubMed Central

Nateghi, Roshanak

2017-01-01

Projecting the long-term trends in energy demand is an increasingly complex endeavor due to the uncertain emerging changes in factors such as climate and policy. The existing energy-economy paradigms used to characterize the long-term trends in the energy sector do not adequately account for climate variability and change. In this paper, we propose a multi-paradigm framework for estimating the climate sensitivity of end-use energy demand that can easily be integrated with the existing energy-economy models. To illustrate the applicability of our proposed framework, we used the energy demand and climate data in the state of Indiana to train a Bayesian predictive model. We then leveraged the end-use demand trends as well as downscaled future climate scenarios to generate probabilistic estimates of the future end-use demand for space cooling, space heating and water heating, at the individual household and building level, in the residential and commercial sectors. Our results indicated that the residential load is much more sensitive to climate variability and change than the commercial load. Moreover, since the largest fraction of the residential energy demand in Indiana is attributed to heating, future warming scenarios could lead to reduced end-use demand due to lower space heating and water heating needs. In the commercial sector, the overall energy demand is expected to increase under the future warming scenarios. This is because the increased cooling load during hotter summer months will likely outpace the reduced heating load during the more temperate winter months. PMID:29155862

Urban stormwater quality, event-mean concentrations, and estimates of stormwater pollutant loads, Dallas-Fort Worth area, Texas, 1992-93

USGS Publications Warehouse

Baldys, Stanley; Raines, T.H.; Mansfield, B.L.; Sandlin, J.T.

1998-01-01

Local regression equations were developed to estimate loads produced by individual storms. Mean annual loads were estimated by applying the storm-load equations for all runoff-producing storms in an average climatic year and summing individual storm loads to determine the annual load.

Use of NARCCAP Model Projections to Develop a Future Typical Meteorological Year and Estimate the Impact of a Changing Climate on Building Energy Consumption

NASA Astrophysics Data System (ADS)

Patton, S. L.; Takle, E. S.; Passe, U.; Kalvelage, K.

2013-12-01

Current simulations of building energy consumption use weather input files based on the past thirty years of climate observations. These 20th century climate conditions may be inadequate when designing buildings meant to function well into the 21st century. An alternative is using model projections of climate change to estimate future risk to the built environment. In this study, model-projected changes in climate were combined with existing typical meteorological year data to create future typical meteorological year data. These data were then formatted for use in EnergyPlus simulation software to evaluate their potential impact on commercial building energy consumption. The modeled climate data were taken from the North American Regional Climate Change Assessment Program (NARCCAP). NARCCAP uses results of global climate models to drive regional climate models, also known as dynamical downscaling. This downscaling gives higher resolution results over specific locations, and the multiple global/regional climate model combinations provide a unique opportunity to quantify the uncertainty of climate change projections and their impacts. Our results show a projected decrease in heating energy consumption and a projected increase in cooling energy consumption for nine locations across the United States for all model combinations. Warmer locations may expect a decrease in heating load of around 30% to 45% and an increase in cooling load of around 25% to 35%. Colder locations may expect a decrease in heating load of around 15% to 25% and an increase in cooling load of around 40% to 70%. The change in net energy consumption is determined by the balance between the magnitudes of heating change and cooling change. Net energy consumption is projected to increase by an average of 5% for lower-latitude locations and decrease by an average of 5% for higher-latitude locations. With these projected annual and seasonal changes presenting strong evidence for the unsuitable nature of current building practices holding up under future climate change, we recommend using our methods and results to make modifications and adaptations to existing buildings and to aid in the design of future buildings.

Stochastic sensitivity analysis of nitrogen pollution to climate change in a river basin with complex pollution sources.

PubMed

Yang, Xiaoying; Tan, Lit; He, Ruimin; Fu, Guangtao; Ye, Jinyin; Liu, Qun; Wang, Guoqing

2017-12-01

It is increasingly recognized that climate change could impose both direct and indirect impacts on the quality of the water environment. Previous studies have mostly concentrated on evaluating the impacts of climate change on non-point source pollution in agricultural watersheds. Few studies have assessed the impacts of climate change on the water quality of river basins with complex point and non-point pollution sources. In view of the gap, this paper aims to establish a framework for stochastic assessment of the sensitivity of water quality to future climate change in a river basin with complex pollution sources. A sub-daily soil and water assessment tool (SWAT) model was developed to simulate the discharge, transport, and transformation of nitrogen from multiple point and non-point pollution sources in the upper Huai River basin of China. A weather generator was used to produce 50 years of synthetic daily weather data series for all 25 combinations of precipitation (changes by - 10, 0, 10, 20, and 30%) and temperature change (increases by 0, 1, 2, 3, and 4 °C) scenarios. The generated daily rainfall series was disaggregated into the hourly scale and then used to drive the sub-daily SWAT model to simulate the nitrogen cycle under different climate change scenarios. Our results in the study region have indicated that (1) both total nitrogen (TN) loads and concentrations are insensitive to temperature change; (2) TN loads are highly sensitive to precipitation change, while TN concentrations are moderately sensitive; (3) the impacts of climate change on TN concentrations are more spatiotemporally variable than its impacts on TN loads; and (4) wide distributions of TN loads and TN concentrations under individual climate change scenario illustrate the important role of climatic variability in affecting water quality conditions. In summary, the large variability in SWAT simulation results within and between each climate change scenario highlights the uncertainty of the impacts of climate change and the need to incorporate extreme conditions in managing water environment and developing climate change adaptation and mitigation strategies.

Effect of occupant behavior and air-conditioner controls on humidity in typical and high-efficiency homes

DOE PAGES

Winkler, Jon; Munk, Jeffrey; Woods, Jason

2018-04-01

Increasing insulation levels and improved windows are reducing sensible cooling loads in high-efficiency homes. This trend raises concerns that the resulting shift in the balance of sensible and latent cooling loads may result in higher indoor humidity, occupant discomfort, and stunted adoption of high-efficiency homes. This study utilizes established moisture-buffering and air-conditioner latent degradation models in conjunction with an approach to stochastically model internal gains. Building loads and indoor humidity levels are compared for simulations of typical new construction homes and high-efficiency homes in 10 US cities. The sensitivity of indoor humidity to changes in cooling set point, air-conditioner capacity,more » and blower control parameters are evaluated. The results show that high-efficiency homes in humid climates have cooling loads with a higher fraction of latent loads than the typical new construction home, resulting in higher indoor humidity. Reducing the cooling set point is the easiest method to reduce indoor humidity, but it is not energy efficient, and overcooling may lead to occupant discomfort. Eliminating the blower operation at the end of cooling cycles and reducing the cooling airflow rate also reduce indoor humidity and with a smaller impact on energy use and comfort.« less

Effect of occupant behavior and air-conditioner controls on humidity in typical and high-efficiency homes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Winkler, Jon; Munk, Jeffrey; Woods, Jason

Increasing insulation levels and improved windows are reducing sensible cooling loads in high-efficiency homes. This trend raises concerns that the resulting shift in the balance of sensible and latent cooling loads may result in higher indoor humidity, occupant discomfort, and stunted adoption of high-efficiency homes. This study utilizes established moisture-buffering and air-conditioner latent degradation models in conjunction with an approach to stochastically model internal gains. Building loads and indoor humidity levels are compared for simulations of typical new construction homes and high-efficiency homes in 10 US cities. The sensitivity of indoor humidity to changes in cooling set point, air-conditioner capacity,more » and blower control parameters are evaluated. The results show that high-efficiency homes in humid climates have cooling loads with a higher fraction of latent loads than the typical new construction home, resulting in higher indoor humidity. Reducing the cooling set point is the easiest method to reduce indoor humidity, but it is not energy efficient, and overcooling may lead to occupant discomfort. Eliminating the blower operation at the end of cooling cycles and reducing the cooling airflow rate also reduce indoor humidity and with a smaller impact on energy use and comfort.« less

Modeling sediment supply of the Congo watershed since the last 23 ka.

NASA Astrophysics Data System (ADS)

Molliex, Stéphane; Kettner, Albert J.; Laurent, Dimitri; Droz, Laurence; Marsset, Tania; Laraque, Alain; Rabineau, Marina

2017-04-01

The Congo River is the world's second river in term of drainage area (3.7 millions of km2) and water discharge (42,000 m3.s-1). Located in equatorial Africa, the basin extends over the two hemispheres, leading to an annual homogeneous repartition of climatic parameters and modest variation in intra-annual discharge. Monitored for decades, a large dataset is available for both the hydrology and sediment load for the Congo system. Moreover, the Quaternary Congo turbidite system geometry has been widely studied and an abundance of paleo-environmental parameters have been inferred from chemical proxies analyzed from offshore cores. These numerous data, both onshore and offshore, allow for accurate calibration of numeric modeling and for efficient comparison between observed and simulated data. This study aims (i) to quantify the evolution of sediment supply leaving the Congo watershed during the last 23 ka; (ii) to decipher the forcing parameters controlling the sediment supply over glacial/interglacial stages. HydroTrend is a model that simulates water discharge and sediment load leaving a hydrologic system. It is based on morphologic, climatic, hydrologic, lithologic, land cover and anthropogenic factors. After calibrating the present-day discharge and sediment load, we simulated discharge and sediment supply over 23 ka, integrating the changes in environmental conditions during this period. Results show that present-day simulations fit the observed data well if a significant part of sediments is being trapped by the catchment, in the floodplain. The long-term simulations show that the changes in climatic conditions (temperature and precipitations) between glacial and interglacial stages only account for a maximum variation of about 20 % of the sediment supply. The resulting land cover changes are most likely a more significant factor controlling the sediment supply; the loss of forest during colder and dryer stages can be responsible for up to 50 % of sediment supply increase.

SIMULATED RESPONSES OF THE GULF OF MEXICO HYPOXIA TO VARIATIONS IN CLIMATE AND ANTHROPOGENIC NUTRIENT LOADING. (R827785E02)

EPA Science Inventory

A mathematical model was used to simulate monthly responses of the Gulf of Mexico hypoxia to variations in climate and anthropogenic nutrient loading over a 45-year period. We examined six hypothetical future scenarios that are based on observed and projected changes in the Mi...

Combined effects of global climate change and regional ecosystem drivers on an exploited marine food web.

PubMed

Niiranen, Susa; Yletyinen, Johanna; Tomczak, Maciej T; Blenckner, Thorsten; Hjerne, Olle; Mackenzie, Brian R; Müller-Karulis, Bärbel; Neumann, Thomas; Meier, H E Markus

2013-11-01

Changes in climate, in combination with intensive exploitation of marine resources, have caused large-scale reorganizations in many of the world's marine ecosystems during the past decades. The Baltic Sea in Northern Europe is one of the systems most affected. In addition to being exposed to persistent eutrophication, intensive fishing, and one of the world's fastest rates of warming in the last two decades of the 20th century, accelerated climate change including atmospheric warming and changes in precipitation is projected for this region during the 21st century. Here, we used a new multimodel approach to project how the interaction of climate, nutrient loads, and cod fishing may affect the future of the open Central Baltic Sea food web. Regionally downscaled global climate scenarios were, in combination with three nutrient load scenarios, used to drive an ensemble of three regional biogeochemical models (BGMs). An Ecopath with Ecosim food web model was then forced with the BGM results from different nutrient-climate scenarios in combination with two different cod fishing scenarios. The results showed that regional management is likely to play a major role in determining the future of the Baltic Sea ecosystem. By the end of the 21st century, for example, the combination of intensive cod fishing and high nutrient loads projected a strongly eutrophicated and sprat-dominated ecosystem, whereas low cod fishing in combination with low nutrient loads resulted in a cod-dominated ecosystem with eutrophication levels close to present. Also, nonlinearities were observed in the sensitivity of different trophic groups to nutrient loads or fishing depending on the combination of the two. Finally, many climate variables and species biomasses were projected to levels unseen in the past. Hence, the risk for ecological surprises needs to be addressed, particularly when the results are discussed in the ecosystem-based management context. © 2013 John Wiley & Sons Ltd.

The susceptibility of large river basins to orogenic and climatic drivers

NASA Astrophysics Data System (ADS)

Haedke, Hanna; Wittmann, Hella; von Blanckenburg, Friedhelm

2017-04-01

Large rivers are known to buffer pulses in sediment production driven by changes in climate as sediment is transported through lowlands. Our new dataset of in situ cosmogenic nuclide concentration and chemical composition of 62 sandy bedload samples from the world largest rivers integrates over 25% of Earth's terrestrial surface, distributed over a variety of climatic zones across all continents, and represents the millennial-scale denudation rate of the sediment's source area. We can show that these denudation rates do not respond to climatic forcing, but faithfully record orogenic forcing, when analyzed with respective variables representing orogeny (strain rate, relief, bouguer anomaly, free-air anomaly), and climate (runoff, temperature, precipitation) and basin properties (floodplain response time, drainage area). In contrast to this orogenic forcing of denudation rates, elemental bedload chemistry from the fine-grained portion of the same samples correlates with climate-related variables (precipitation, runoff) and floodplain response times. It is also well-known from previous compilations of river-gauged sediment loads that the short-term basin-integrated sediment export is also climatically controlled. The chemical composition of detrital sediment shows a climate control that can originate in the rivers source area, but this signal is likely overprinted during transfer through the lowlands because we also find correlation with floodplain response times. At the same time, cosmogenic nuclides robustly preserve the orogenic forcing of the source area denudation signal through of the floodplain buffer. Conversely, previous global compilations of cosmogenic nuclides in small river basins show the preservation of climate drivers in their analysis, but these are buffered in large lowland rivers. Hence, we can confirm the assumption that cosmogenic nuclides in large rivers are poorly susceptible to climate changes, but are at the same time highly suited to detect changes in orogenic forcing in their paleo sedimentary records.

A dynamic modelling approach for estimating critical loads of nitrogen based on plant community changes under a changing climate.

PubMed

Belyazid, Salim; Kurz, Dani; Braun, Sabine; Sverdrup, Harald; Rihm, Beat; Hettelingh, Jean-Paul

2011-03-01

A dynamic model of forest ecosystems was used to investigate the effects of climate change, atmospheric deposition and harvest intensity on 48 forest sites in Sweden (n = 16) and Switzerland (n = 32). The model was used to investigate the feasibility of deriving critical loads for nitrogen (N) deposition based on changes in plant community composition. The simulations show that climate and atmospheric deposition have comparably important effects on N mobilization in the soil, as climate triggers the release of organically bound nitrogen stored in the soil during the elevated deposition period. Climate has the most important effect on plant community composition, underlining the fact that this cannot be ignored in future simulations of vegetation dynamics. Harvest intensity has comparatively little effect on the plant community in the long term, while it may be detrimental in the short term following cutting. This study shows: that critical loads of N deposition can be estimated using the plant community as an indicator; that future climatic changes must be taken into account; and that the definition of the reference deposition is critical for the outcome of this estimate. Copyright © 2010 Elsevier Ltd. All rights reserved.

Estimation of ozone dry deposition over Europe for the period 2071-2100

NASA Astrophysics Data System (ADS)

Komjáthy, Eszter; Gelybó, Györgyi; László Lagzi, István.; Mészáros, Róbert

2010-05-01

Ozone in the lower troposphere is a phytotoxic air pollutant which can cause injury to plant tissues, causing reduction in plant growth and productivity. In the last decades, several investigations have been carried out for the purpose to estimate ozone load over different surface types. At the same time, the changes of atmospheric variables as well as surface/vegetation parameters due to the global climate change could also strongly modify both temporal and spatial variations of ozone load over Europe. In this study, the possible effects of climate change on ozone deposition are analyzed. Using a sophisticated deposition model, ozone deposition was estimated on a regular grid over Europe for the period 2071-2100. Our aim is to determine the uncertainties and the possible degree of change in ozone deposition velocity as an important predictor of total ozone load using climate data from multiple climate models and runs. For these model calculations, results of the PRUDENCE (Predicting of Regional Scenarios and Uncertainties for Defining European Climate Change Risks and Effects) climate prediction project were used. As a first step, seasonal variations of ozone deposition over different vegetation types in case of different climate scenarios are presented in this study. Besides model calculations, in the frame of a sensitivity analyses, the effects of surface/vegetation parameters (e.g. leaf area index or stomatal resistance) on ozone deposition under a modified climate regime have also been analyzed.

Climatic pacing of Mediterranean fire histories from lake sedimentary microcharcoal

NASA Astrophysics Data System (ADS)

Turner, R.; Roberts, N.; Jones, M. D.

2008-10-01

The microcharcoal content (particles < 180 µm) of overlapping sedimentary sequences from two crater lake basins in central Turkey are used to reconstruct the regional fire history of the East Mediterranean oak-grass parkland zone from the Last Glacial Maximum to the present-day. These results are correlated with stable isotope and pollen data from the same cores in order to assess the changing role of climate, vegetation and human activity in landscape burning. This indicates that climatically-induced variation in biomass availability was the main factor controlling the timing of regional fire activity during the Last Glacial-Interglacial climatic transition, and again during Mid-Holocene times, with fire frequency and magnitude increasing during wetter climatic phases. Spectral analysis of the Holocene part of the record from Eski Acıgöl indicates significant cyclicity with a periodicity of ~ 1500 years that may be linked with large-scale climate forcing. Although proto-agricultural societies were established in this region as early as 10,000 years ago, it is only during the last two to three millennia that the pacing of wildfire cycles appears to have become decoupled from climate and linked instead to human-induced changes in land cover and fuel load availability.

Introduction to Building Systems Performance: Houses That Work II. Revised February 2005

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

2005-03-01

Buildings should be suited to their environments. Design and construction must be responsive to varying seismic risks, wind loads, and snow loads, as well as soil conditions, frost depth, orientation, and solar radiation. In addition, building envelopes and mechanical systems should be designed for a specific hygro-thermal regions, rain exposure, and interior climate. The Building Science Consortium (BSC) design recommendations are based on the hygro-thermal regions with reference to the annual rainfall. Local climate must be addressed if it differs significantly from the climate described for a particular design.

Assessing the impacts of future climate conditions on the effectiveness of winter cover crops in reducing nitrate loads into the Chesapeake Bay Watersheds using SWAT model

USDA-ARS?s Scientific Manuscript database

Winter cover crops (WCCs) have been widely implemented in the Coastal Plain of the Chesapeake Bay watershed (CBW) due to their high effectiveness at reducing nitrate loads. However, future climate conditions (FCCs) are expected to exacerbate water quality degradation in the CBW by increasing nitrat...

Watershed Modeling to Assess the Sensitivity of Streamflow, Nutrient, and Sediment Loads to Potential Climate Change and Urban Development in 20 U.S. Watersheds (Final Report)

EPA Science Inventory

In September 2013, EPA announced the release of the final report, Watershed Modeling to Assess the Sensitivity of Streamflow, Nutrient, and Sediment Loads to Potential Climate Change and Urban Development in 20 U.S. Watersheds.

Watershed modeling was conducted in ...

Application of the coastal generalized ecosystem model (CGEM) to assess the impacts of a potential future climate scenario on northern Gulf of Mexico hypoxia

EPA Science Inventory

Mechanistic hypoxia models for the northern Gulf of Mexico are being used to guide policy goals for Mississippi River nutrient loading reductions. However, to date, these models have not examined the effects of both nutrient loads and future climate. Here, we simulate a future c...

Energy Performance and Optimal Control of Air-conditioned Buildings Integrated with Phase Change Materials

NASA Astrophysics Data System (ADS)

Zhu, Na

This thesis presents an overview of the previous research work on dynamic characteristics and energy performance of buildings due to the integration of PCMs. The research work on dynamic characteristics and energy performance of buildings using PCMs both with and without air-conditioning is reviewed. Since the particular interest in using PCMs for free cooling and peak load shifting, specific research efforts on both subjects are reviewed separately. A simplified physical dynamic model of building structures integrated with SSPCM (shaped-stabilized phase change material) is developed and validated in this study. The simplified physical model represents the wall by 3 resistances and 2 capacitances and the PCM layer by 4 resistances and 2 capacitances respectively while the key issue is the parameter identification of the model. This thesis also presents the studies on the thermodynamic characteristics of buildings enhanced by PCM and on the investigation of the impacts of PCM on the building cooling load and peak cooling demand at different climates and seasons as well as the optimal operation and control strategies to reduce the energy consumption and energy cost by reducing the air-conditioning energy consumption and peak load. An office building floor with typical variable air volume (VAV) air-conditioning system is used and simulated as the reference building in the comparison study. The envelopes of the studied building are further enhanced by integrating the PCM layers. The building system is tested in two selected cities of typical climates in China including Hong Kong and Beijing. The cold charge and discharge processes, the operation and control strategies of night ventilation and the air temperature set-point reset strategy for minimizing the energy consumption and electricity cost are studied. This thesis presents the simulation test platform, the test results on the cold storage and discharge processes, the air-conditioning energy consumption and demand reduction potentials in typical air-conditioning seasons in typical China cites as well as the impacts of operation and control strategies.

Air Pollution Prevention and Control Policy in China.

PubMed

Huang, Cunrui; Wang, Qiong; Wang, Suhan; Ren, Meng; Ma, Rui; He, Yiling

2017-01-01

With rapid urbanization and development of transport infrastructure, air pollution caused by multiple-pollutant emissions and vehicle exhaust has been aggravated year by year in China. In order to improve air quality, the Chinese authorities have taken a series of actions to control air pollution emission load within a permissible range. However, although China has made positive progress on tackling air pollution, these actions have not kept up with its economy growth and fossil-fuel use. The traditional single-pollutant approach is far from enough in China now, and in the near future, air pollution control strategies should move in the direction of the multiple-pollutant approach. In addition, undesirable air quality is usually linked with the combination of high emissions and adverse weather conditions. However, few studies have been done on the influence of climate change on atmospheric chemistry in the global perspective. Available evidence suggested that climate change is likely to exacerbate certain kinds of air pollutants including ozone and smoke from wildfires. This has become a major public health problem because the interactions of global climate change, urban heat islands, and air pollution have adverse effects on human health. In this chapter, we first review the past and current circumstances of China's responses to air pollution. Then we discuss the control challenges and future options for a better air quality in China. Finally, we begin to unravel links between air pollution and climate change, providing new opportunities for integrated research and actions in China.

Literature Review of Low Impact Development for Stormwater Control

DTIC Science & Technology

2015-05-30

appropriate LID technology can be selected to capture the targeted vi metal pollutant. Little information exists on the effects of field variables such as...loading rates and volume, temperature , climate, pH, sediments, organics, and maintenance cycles on systems in the field. 4. The amount of research...maximum extent technically feasible, the pre-development hydrology of the property with regard to the temperature , rate, volume, and duration of flow

Climate change and agricultural development: adapting Polish agriculture to reduce future nutrient loads in a coastal watershed.

PubMed

Piniewski, Mikołaj; Kardel, Ignacy; Giełczewski, Marek; Marcinkowski, Paweł; Okruszko, Tomasz

2014-09-01

Currently, there is a major concern about the future of nutrient loads discharged into the Baltic Sea from Polish rivers because they are main contributors to its eutrophication. To date, no watershed-scale studies have properly addressed this issue. This paper fills this gap by using a scenario-modeling framework applied in the Reda watershed, a small (482 km²) agricultural coastal area in northern Poland. We used the SWAT model to quantify the effects of future climate, land cover, and management changes under multiple scenarios up to the 2050s. The combined effect of climate and land use change on N-NO3 and P-PO4 loads is an increase by 20-60 and 24-31 %, respectively, depending on the intensity of future agricultural usage. Using a scenario that assumes a major shift toward a more intensive agriculture following the Danish model would bring significantly higher crop yields but cause a great deterioration of water quality. Using vegetative cover in winter and spring (VC) would be a very efficient way to reduce future P-PO4 loads so that they are lower than levels observed at present. However, even the best combination of measures (VC, buffer zones, reduced fertilization, and constructed wetlands) would not help to remediate heavily increased N-NO3 loads due to climate change and agricultural intensification.

Impacts of climate change on in-stream nitrogen in a lowland chalk stream: an appraisal of adaptation strategies.

PubMed

Whitehead, P G; Wilby, R L; Butterfield, D; Wade, A J

2006-07-15

The impacts of climate change on nitrogen (N) in a lowland chalk stream are investigated using a dynamic modelling approach. The INCA-N model is used to simulate transient daily hydrology and water quality in the River Kennet using temperature and precipitation scenarios downscaled from the General Circulation Model (GCM) output for the period 1961-2100. The three GCMs (CGCM2, CSIRO and HadCM3) yield very different river flow regimes with the latter projecting significant periods of drought in the second half of the 21st century. Stream-water N concentrations increase over time as higher temperatures enhance N release from the soil, and lower river flows reduce the dilution capacity of the river. Particular problems are shown to occur following severe droughts when N mineralization is high and the subsequent breaking of the drought releases high nitrate loads into the river system. Possible strategies for reducing climate-driven N loads are explored using INCA-N. The measures include land use change or fertiliser reduction, reduction in atmospheric nitrate and ammonium deposition, and the introduction of water meadows or connected wetlands adjacent to the river. The most effective strategy is to change land use or reduce fertiliser use, followed by water meadow creation, and atmospheric pollution controls. Finally, a combined approach involving all three strategies is investigated and shown to reduce in-stream nitrate concentrations to those pre-1950s even under climate change.

Comparative study of adaptive controller using MIT rules and Lyapunov method for MPPT standalone PV systems

NASA Astrophysics Data System (ADS)

Tariba, N.; Bouknadel, A.; Haddou, A.; Ikken, N.; Omari, Hafsa El; Omari, Hamid El

2017-01-01

The Photovoltaic Generator have a nonlinear characteristic function relating the intensity at the voltage I = f (U) and depend on the variation of solar irradiation and temperature, In addition, its point of operation depends directly on the load that it supplies. To fix this drawback, and to extract the maximum power available to the terminal of the generator, an adaptation stage is introduced between the generator and the load to couple the two elements as perfectly as possible. The adaptation stage is associated with a command called MPPT MPPT (Maximum Power Point Tracker) whose is used to force the PVG to operate at the MPP (Maximum Power Point) under variation of climatic conditions and load variation. This paper presents a comparative study between the adaptive controller for PV Systems using MIT rules and Lyapunov method to regulate the PV voltage. The Incremental Conductance (IC) algorithm is used to extract the maximum power from the PVG by calculating the voltage Vref, and the adaptive controller is used to regulate and track quickly the PV voltage. The two methods of the adaptive controller will be compared to prove their performance by using the PSIM tools and experimental test, and the mathematical model of step-up with PVG model will be presented.

Varroa destructor (Mesostigmata: Varroidae) Parasitism and Climate Differentially Influence the Prevalence, Levels, and Overt Infections of Deformed Wing Virus in Honey Bees (Hymenoptera: Apidae)

PubMed Central

Guzman-Novoa, Ernesto; Md. Hamiduzzaman, Mollah; Espinosa-Montaño, Laura G.; Correa-Benítez, Adriana

2016-01-01

The prevalence and loads of deformed wing virus (DWV) between honey bee (Apis mellifera L.) colonies from a tropical and a temperate environment were compared. The interaction between these environments and the mite Varroa destructor in relation to DWV prevalence, levels, and overt infections, was also analyzed. V. destructor rates were determined, and samples of mites, adult bees, brood parasitized with varroa mites and brood not infested by mites were analyzed. DWV was detected in 100% of the mites and its prevalence and loads in honey bees were significantly higher in colonies from the temperate climate than in colonies from the tropical climate. Significant interactions were found between climate and type of sample, with the highest levels of DWV found in varroa-parasitized brood from temperate climate colonies. Additionally, overt infections were observed only in the temperate climate. Varroa parasitism and DWV loads in bees from colonies with overt infections were significantly higher than in bees from colonies with covert infections. These results suggest that interactions between climate, V. destructor, and possibly other factors, may play a significant role in the prevalence and levels of DWV in honey bee colonies, as well as in the development of overt infections. Several hypotheses are discussed to explain these results. PMID:27252482

Watershed Modeling to Assess the Sensitivity of Streamflow, Nutrient, and Sediment Loads to Potential Climate Change and Urban Development in 20 U.S. Watersheds (External Review Draft)

EPA Science Inventory

EPA has released for independent external peer review and public comment a draft report titled, Watershed Modeling to Assess the Sensitivity of Streamflow, Nutrient, and Sediment Loads to Potential Climate Change and Urban Development in 20 U.S. Watersheds. This is a draft...

El-Niño/Southern Oscillation (ENSO) influences on monthly NO 3 load and concentration, stream flow and precipitation in the Little River Watershed, Tifton, Georgia (GA)

NASA Astrophysics Data System (ADS)

Keener, V. W.; Feyereisen, G. W.; Lall, U.; Jones, J. W.; Bosch, D. D.; Lowrance, R.

2010-02-01

SummaryAs climate variability increases, it is becoming increasingly critical to find predictable patterns that can still be identified despite overall uncertainty. The El-Niño/Southern Oscillation is the best known pattern. Its global effects on weather, hydrology, ecology and human health have been well documented. Climate variability manifested through ENSO has strong effects in the southeast United States, seen in precipitation and stream flow data. However, climate variability may also affect water quality in nutrient concentrations and loads, and have impacts on ecosystems, health, and food availability in the southeast. In this research, we establish a teleconnection between ENSO and the Little River Watershed (LRW), GA., as seen in a shared 3-7 year mode of variability for precipitation, stream flow, and nutrient load time series. Univariate wavelet analysis of the NINO 3.4 index of sea surface temperature (SST) and of precipitation, stream flow, NO 3 concentration and load time series from the watershed was used to identify common signals. Shared 3-7 year modes of variability were seen in all variables, most strongly in precipitation, stream flow and nutrient load in strong El Niño years. The significance of shared 3-7 year periodicity over red noise with 95% confidence in SST and precipitation, stream flow, and NO 3 load time series was confirmed through cross-wavelet and wavelet-coherence transforms, in which common high power and co-variance were computed for each set of data. The strongest 3-7 year shared power was seen in SST and stream flow data, while the strongest co-variance was seen in SST and NO 3 load data. The strongest cross-correlation was seen as a positive value between the NINO 3.4 and NO 3 load with a three-month lag. The teleconnection seen in the LRW between the NINO 3.4 index and precipitation, stream flow, and NO 3 load can be utilized in a model to predict monthly nutrient loads based on short-term climate variability, facilitating management in high risk seasons.

A first look at the influence of anthropogenic climate change on the future delivery of fluvial sediment to the Ganges-Brahmaputra-Meghna delta.

PubMed

Darby, Stephen E; Dunn, Frances E; Nicholls, Robert J; Rahman, Munsur; Riddy, Liam

2015-09-01

We employ a climate-driven hydrological water balance and sediment transport model (HydroTrend) to simulate future climate-driven sediment loads flowing into the Ganges-Brahmaputra-Meghna (GBM) mega-delta. The model was parameterised using high-quality topographic data and forced with daily temperature and precipitation data obtained from downscaled Regional Climate Model (RCM) simulations for the period 1971-2100. Three perturbed RCM model runs were selected to quantify the potential range of future climate conditions associated with the SRES A1B scenario. Fluvial sediment delivery rates to the GBM delta associated with these climate data sets are projected to increase under the influence of anthropogenic climate change, albeit with the magnitude of the increase varying across the two catchments. Of the two study basins, the Brahmaputra's fluvial sediment load is predicted to be more sensitive to future climate change. Specifically, by the middle part of the 21(st) century, our model results suggest that sediment loads increase (relative to the 1981-2000 baseline period) over a range of between 16% and 18% (depending on climate model run) for the Ganges, but by between 25% and 28% for the Brahmaputra. The simulated increase in sediment flux emanating from the two catchments further increases towards the end of the 21(st) century, reaching between 34% and 37% for the Ganges and between 52% and 60% for the Brahmaputra by the 2090s. The variability in these changes across the three climate change simulations is small compared to the changes, suggesting they represent a significant increase. The new data obtained in this study offer the first estimate of whether and how anthropogenic climate change may affect the delivery of fluvial sediment to the GBM delta, informing assessments of the future sustainability and resilience of one of the world's most vulnerable mega-deltas. Specifically, such significant increases in future sediment loads could increase the resilience of the delta to sea-level rise by giving greater potential for vertical accretion. However, these increased sediment fluxes may not be realised due to uncertainties in the monsoon related response to climate change or other human-induced changes in the catchment: this is a subject for further research.

Analyzing the effect of the longwave emissivity and solar reflectance of building envelopes on energy-saving in buildings in various climates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shi, Zhiyang; Zhang, Xiong

A dynamic computer simulation is carried out in the climates of 35 cities distributed around the world. The variation of the annual air-conditioning energy loads due to changes in the longwave emissivity and the solar reflectance of the building envelopes is studied to find the most appropriate exterior building finishes in various climates (including a tropical climate, a subtropical climate, a mountain plateau climate, a frigid-temperate climate and a temperate climate). Both the longwave emissivity and the solar reflectance are set from 0.1 to 0.9 with an interval of 0.1 in the simulation. The annual air-conditioning energy loads trends ofmore » each city are listed in a chart. The results show that both the longwave emissivity and the solar reflectance of building envelopes play significant roles in energy-saving for buildings. In tropical climates, the optical parameters of the building exterior surface affect the building energy-saving most significantly. In the mountain plateau climates and the subarctic climates, the impacts on energy-saving in buildings due to changes in the longwave emissivity and the solar reflectance are still considerable, but in the temperate continental climates and the temperate maritime climates, only limited effects are seen. (author)« less

Quantifying the combined effects of land use and climate changes on stream flow and nutrient loads: A modelling approach in the Odense Fjord catchment (Denmark).

PubMed

Molina-Navarro, Eugenio; Andersen, Hans E; Nielsen, Anders; Thodsen, Hans; Trolle, Dennis

2018-04-15

Water pollution and water scarcity are among the main environmental challenges faced by the European Union, and multiple stressors compromise the integrity of water resources and ecosystems. Particularly in lowland areas of northern Europe, high population density, flood protection and, especially, intensive agriculture, are important drivers of water quality degradation. In addition, future climate and land use changes may interact, with uncertain consequences for water resources. Modelling approaches have become essential to address water issues and to evaluate ecosystem management. In this work, three multi-stressor future storylines combining climatic and socio-economic changes, defined at European level, have been downscaled for the Odense Fjord catchment (Denmark), giving three scenarios: High-Tech agriculture (HT), Agriculture for Nature (AN) and Market-Driven agriculture (MD). The impacts of these scenarios on water discharge and inorganic and organic nutrient loads to the streams have been simulated using the Soil and Water Assessment Tool (SWAT). The results revealed that the scenario-specific climate inputs were most important when simulating hydrology, increasing river discharge in the HT and MD scenarios (which followed the high emission 8.5 representative concentration pathway, RCP), while remaining stable in the AN scenario (RCP 4.5). Moreover, discharge was the main driver of changes in organic nutrients and inorganic phosphorus loads that consequently increased in a high emission scenario. Nevertheless, both land use (via inputs of fertilizer) and climate changes affected the nitrate transport. Different levels of fertilization yielded a decrease in the nitrate load in AN and an increase in MD. In HT, however, nitrate losses remained stable because the fertilization decrease was counteracted by a flow increase. Thus, our results suggest that N loads will ultimately depend on future land use and management in an interaction with climate changes, and this knowledge is of utmost importance for the achievement of European environmental policy goals. Copyright © 2017 Elsevier B.V. All rights reserved.

Climate change, renewable energy and population impact on future energy demand for Burkina Faso build environment

NASA Astrophysics Data System (ADS)

Ouedraogo, B. I.

This research addresses the dual challenge faced by Burkina Faso engineers to design sustainable low-energy cost public buildings and domestic dwellings while still providing the required thermal comfort under warmer temperature conditions caused by climate change. It was found base don climate change SRES scenario A2 that predicted mean temperature in Burkina Faso will increase by 2oC between 2010 and 2050. Therefore, in order to maintain a thermally comfortable 25oC inside public buildings, the projected annual energy consumption for cooling load will increase by 15%, 36% and 100% respectively for the period between 2020 to 2039, 2040 to 2059 and 2070 to 2089 when compared to the control case. It has also been found that a 1% increase in population growth will result in a 1.38% and 2.03% increase in carbon emission from primary energy consumption and future electricity consumption respectively. Furthermore, this research has investigated possible solutions for adaptation to the severe climate change and population growth impact on energy demand in Burkina Faso. Shading devices could potentially reduce the cooling load by up to 40%. Computer simulation programming of building energy consumption and a field study has shown that adobe houses have the potential of significantly reducing energy demand for cooling and offer a formidable method for climate change adaptation. Based on the Net Present Cost, hybrid photovoltaic (PV) and Diesel generator energy production configuration is the most cost effective local electricity supply system, for areas without electricity at present, with a payback time of 8 years when compared to diesel generator stand-alone configuration. It is therefore a viable solution to increase electricity access to the majority of the population.

The competing impacts of climate change and nutrient reductions on dissolved oxygen in Chesapeake Bay

NASA Astrophysics Data System (ADS)

Irby, Isaac D.; Friedrichs, Marjorie A. M.; Da, Fei; Hinson, Kyle E.

2018-05-01

The Chesapeake Bay region is projected to experience changes in temperature, sea level, and precipitation as a result of climate change. This research uses an estuarine-watershed hydrodynamic-biogeochemical modeling system along with projected mid-21st-century changes in temperature, freshwater flow, and sea level rise to explore the impact climate change may have on future Chesapeake Bay dissolved-oxygen (DO) concentrations and the potential success of nutrient reductions in attaining mandated estuarine water quality improvements. Results indicate that warming bay waters will decrease oxygen solubility year-round, while also increasing oxygen utilization via respiration and remineralization, primarily impacting bottom oxygen in the spring. Rising sea level will increase estuarine circulation, reducing residence time in bottom waters and increasing stratification. As a result, oxygen concentrations in bottom waters are projected to increase, while oxygen concentrations at mid-depths (3 < DO < 5 mg L-1) will typically decrease. Changes in precipitation are projected to deliver higher winter and spring freshwater flow and nutrient loads, fueling increased primary production. Together, these multiple climate impacts will lower DO throughout the Chesapeake Bay and negatively impact progress towards meeting water quality standards associated with the Chesapeake Bay Total Maximum Daily Load. However, this research also shows that the potential impacts of climate change will be significantly smaller than improvements in DO expected in response to the required nutrient reductions, especially at the anoxic and hypoxic levels. Overall, increased temperature exhibits the strongest control on the change in future DO concentrations, primarily due to decreased solubility, while sea level rise is expected to exert a small positive impact and increased winter river flow is anticipated to exert a small negative impact.

Impact of Infiltration and Ventilation on Measured Space Conditioning Energy and Moisture Levels in the Hot-Humid Climate, Cocoa, Florida (Fact Sheet)

DOE Office of Scientific and Technical Information (OSTI.GOV)

None, None

Air infiltration and ventilation in residential buildings is a very large part of the heating loads, but empirical data regarding the impact on space cooling has been lacking. Moreover, there has been little data on how building tightness might relate to building interior moisture levels in homes in a hot and humid climate. To address this need, BA-PIRC has conducted research to assess the moisture and cooling load impacts of airtightness and mechanical ventilation in two identical laboratory homes in the hot-humid climate over the cooling season.

Technology Solutions Case Study: Impact of Infiltration and Ventilation on Measured Space Conditioning Energy and Moisture Levels in the Hot-Humid Climate

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

Air infiltration and ventilation in residential buildings is a very large part of the heating loads, but empirical data regarding the impact on space cooling has been lacking. Moreover, there has been little data on how building tightness might relate to building interior moisture levels in homes in a hot and humid climate. To address this need, BA-PIRC conducted research to assess the moisture and cooling load impacts of airtightness and mechanical ventilation in two identical laboratory homes in the hot-humid climate over the cooling season.

Introduction to Building Systems Performance: Houses That Work II; Period of Performance: January 2003--December 2003

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

2004-04-01

Buildings should be suited to their environments. Design and construction must be responsive to varying seismic risks, wind loads, and snow loads, as well as soil conditions, frost depth, orientation, and solar radiation. In addition, building envelopes and mechanical systems should be designed for a specific hygro-thermal regions, rain exposure, and interior climate. The Building Science Consortium (BSC) design recommendations are based on the hygro-thermal regions with reference to the annual rainfall. Local climate must be addressed if it differs significantly from the climate described for a particular design.

The critical role of fire in catchment coevolution in South Eastern Australia

NASA Astrophysics Data System (ADS)

Nyman, P.; Inbar, A.; Lane, P. N. J.; Sheridan, G. J.

2016-12-01

Temperate south east Australian forested uplands are characterised by complex spatial patterns in forest types, soils and fire regimes, even within areas with similar geologies and landscape position. Preliminary measurements and experiments suggest that positive and negative feedbacks between the vegetation, fuels, fire frequency and soil erosion may control the coevolution of these observed system states. Here we propose the hypotheses that in this landscape post-fire soil erosion has played a dominant role in the coevolved system-state combinations of standing biomass, fire frequency and soil depth. To test the hypothesis a 1D simulation model was developed that links together an ecohydrological model to drive the biomass production and water and energy partitioning, a stochastic fire model that is controlled by climate, fuel load and moisture conditions, and a geomorphic model that controls soil production and fluvial and diffusive sediment transport rates. The model was calibrated to the range of existing observed quasi-equalibrium system-states of soil depth, standing biomass, fuel loading and fire frequency using field measurements from 12 instrumented eco-hydrologic microclimate research sites. The long-term partitioning of rainfall into evaporation, transpiration, and streamflow was calibrated against field and literature values. Fuel moisture and micro-climate variables were calibrated to the field microclimate stations. The calibrated model was able to reasonably replicate the observed quasi-equilibrium system-states and hydrologic outputs using current climate forcings operating over a 10,000 year period, providing confidence in the model structure and performance. The model was then used to test the hypothesis stated above, by alternatively including or excluding the post fire erosion process. An alternate hypothesis, whereby the observed system states are dominated by climate related differences in soil production rates was also tested in this way. The results support the hypothesis that feedbacks between fire, ecology, hydrology and geomorphology have played a critical role in the coevolution of south east Australian forested uplands. Similar pyro-eco-hydrologic feedbacks may play a critical role in catchment coevolution in other forested systems globally.

Impact of Paint Color on Rest Period Climate Control Loads in Long-Haul Trucks: Preprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lustbader, J.; Kreutzer, C.; Jeffers, M.

Cab climate conditioning is one of the primary reasons for operating the main engine in a long-haul truck during driver rest periods. In the United States, sleeper cab trucks use approximately 667 million gallons of fuel annually for rest period idling. The U.S. Department of Energy's National Renewable Energy Laboratory's (NREL) CoolCab Project works closely with industry to design efficient thermal management systems for long-haul trucks that minimize engine idling and fuel use while maintaining occupant comfort. Heat transfer to the vehicle interior from opaque exterior surfaces is one of the major heat pathways that contribute to air conditioning loadsmore » during long-haul truck daytime rest period idling. To quantify the impact of paint color and the opportunity for advanced paints, NREL collaborated with Volvo Group North America, PPG Industries, and Dometic Environmental Corporation. Initial screening simulations using CoolCalc, NREL's rapid HVAC load estimation tool, showed promising air-conditioning load reductions due to paint color selection. Tests conducted at NREL's Vehicle Testing and Integration Facility using long-haul truck cab sections, 'test bucks,' showed a 31.1% of maximum possible reduction in rise over ambient temperature and a 20.8% reduction in daily electric air conditioning energy use by switching from black to white paint. Additionally, changing from blue to an advanced color-matched solar reflective blue paint resulted in a 7.3% reduction in daily electric air conditioning energy use for weather conditions tested in Colorado. National-level modeling results using weather data from major U.S. cities indicated that the increase in heating loads due to lighter paint colors is much smaller than the reduction in cooling loads.« less

Application of Climate Assessment Tool (CAT) to estimate climate variability impacts on nutrient loading from local watersheds

Treesearch

Ying Ouyang; Prem B. Parajuli; Gary Feng; Theodor D. Leininger; Yongshan Wan; Padmanava Dash

2018-01-01

A vast amount of future climate scenario datasets, created by climate models such as general circulation models (GCMs), have been used in conjunction with watershed models to project future climate variability impact on hydrological processes and water quality. However, these low spatial-temporal resolution datasets are often difficult to downscale spatially and...

Groundwater nitrate pollution and climate change: learnings from a water balance-based analysis of several aquifers in a western Mediterranean region (Catalonia).

PubMed

Mas-Pla, Josep; Menció, Anna

2018-04-11

Climate change will affect the dynamics of the hydrogeological systems and their water resources quality; in particular nitrate, which is herein taken as a paradigmatic pollutant to illustrate the effects of climate change on groundwater quality. Based on climatic predictions of temperature and precipitation for the horizon of 2021 and 2050, as well as on land use distribution, water balances are recalculated for the hydrological basins of distinct aquifer systems in a western Mediterranean region as Catalonia (NE Spain) in order to determine the reduction of available water resources. Besides the fact that climate change will represent a decrease of water availability, we qualitatively discuss the modifications that will result from the future climatic scenarios and their impact on nitrate pollution according to the geological setting of the selected aquifers. Climate effects in groundwater quality are described according to hydrological, environmental, socio-economic, and political concerns. Water reduction stands as a major issue that will control stream-aquifer interactions and subsurface recharge, leading to a general modification of nitrate in groundwater as dilution varies. A nitrate mass balance model provides a gross estimation of potential nitrate evolution in these aquifers, and it points out that the control of the fertilizer load will be crucial to achieve adequate nitrate content in groundwater. Reclaimed wastewater stands as local reliable resource, yet its amount will only satisfy a fraction of the loss of available resources due to climate change. Finally, an integrated management perspective is necessary to avoid unplanned actions from private initiatives that will jeopardize the achievement of sustainable water resources exploitation under distinct hydrological scenarios.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shah, Nihar K.; Wei, Max; Letschert, Virginie

Hydrofluorocarbons (HFCs) emitted from uses such as refrigerants and thermal insulating foam, are now the fastest growing greenhouse gases (GHGs), with global warming potentials (GWP) thousands of times higher than carbon dioxide (CO2). Because of the short lifetime of these molecules in the atmosphere,1 mitigating the amount of these short-lived climate pollutants (SLCPs) provides a faster path to climate change mitigation than control of CO2 alone. This has led to proposals from Africa, Europe, India, Island States, and North America to amend the Montreal Protocol on Substances that Deplete the Ozone Layer (Montreal Protocol) to phase-down high-GWP HFCs. Simultaneously, energymore » efficiency market transformation programs such as standards, labeling and incentive programs are endeavoring to improve the energy efficiency for refrigeration and air conditioning equipment to provide life cycle cost, energy, GHG, and peak load savings. In this paper we provide an estimate of the magnitude of such GHG and peak electric load savings potential, for room air conditioning, if the refrigerant transition and energy efficiency improvement policies are implemented either separately or in parallel.« less

Agricultural nutrient loadings to the freshwater environment: the role of climate change and socioeconomic change

NASA Astrophysics Data System (ADS)

Xie, Hua; Ringler, Claudia

2017-10-01

Human activities, in particular agricultural production, interfere with natural cycles of nutrient elements, nitrogen (N) and phosphorus (P), leading to growing concerns about water quality degradation related to excessive nutrient loadings. Increases in agricultural production in response to population growth and wealth generation further increase risks associated with nutrient pollution. This paper presents results from projections of nutrient exports from global agricultural crop and pasture systems to the water environment generated using a process-based modeling approach. Brazil, China, India and the United States account for more than half of estimated global N and P loadings in the base year. Each country boasts large agriculture centers where high calculated loading values are found. Rapid growth in global agricultural nutrient loadings is projected. Growth of agricultural pollution loading is fastest in the group of low-income developing countries and loading growth rates also vary substantially with climate change scenario. Counter measures need to be taken to address the environmental risks associated with the projected rapid increase of agricultural nutrient loadings.

Simulation of in-stream water quality on global scale under changing climate and anthropogenic conditions

NASA Astrophysics Data System (ADS)

Voss, Anja; Bärlund, Ilona; Punzet, Manuel; Williams, Richard; Teichert, Ellen; Malve, Olli; Voß, Frank

2010-05-01

Although catchment scale modelling of water and solute transport and transformations is a widely used technique to study pollution pathways and effects of natural changes, policies and mitigation measures there are only a few examples of global water quality modelling. This work will provide a description of the new continental-scale model of water quality WorldQual and the analysis of model simulations under changed climate and anthropogenic conditions with respect to changes in diffuse and point loading as well as surface water quality. BOD is used as an indicator of the level of organic pollution and its oxygen-depleting potential, and for the overall health of aquatic ecosystems. The first application of this new water quality model is to river systems of Europe. The model itself is being developed as part of the EU-funded SCENES Project which has the principal goal of developing new scenarios of the future of freshwater resources in Europe. The aim of the model is to determine chemical fluxes in different pathways combining analysis of water quantity with water quality. Simple equations, consistent with the availability of data on the continental scale, are used to simulate the response of in-stream BOD concentrations to diffuse and anthropogenic point loadings as well as flow dilution. Point sources are divided into manufacturing, domestic and urban loadings, whereas diffuse loadings come from scattered settlements, agricultural input (for instance livestock farming), and also from natural background sources. The model is tested against measured longitudinal gradients and time series data at specific river locations with different loading characteristics like the Thames that is driven by domestic loading and Ebro with relative high share of diffuse loading. With scenario studies the influence of climate and anthropogenic changes on European water resources shall be investigated with the following questions: 1. What percentage of river systems will have degraded water quality due to different driving forces? 2. How will climate change and changes in wastewater discharges affect water quality? For the analysis these scenario aspects are included: 1. climate with changed runoff (affecting diffuse pollution and loading from sealed areas), river discharge (causing dilution or concentration of point source pollution) and water temperature (affecting BOD degradation). 2. Point sources with changed population (affecting domestic pollution), connectivity to treatment plants (influencing domestic and manufacturing pollution as well as input from sealed areas and scattered settlements).

Source-Based Modeling Of Urban Stormwater Quality Response to the Selected Scenarios Combining Future Changes in Climate and Socio-Economic Factors

NASA Astrophysics Data System (ADS)

Borris, Matthias; Leonhardt, Günther; Marsalek, Jiri; Österlund, Heléne; Viklander, Maria

2016-08-01

The assessment of future trends in urban stormwater quality should be most helpful for ensuring the effectiveness of the existing stormwater quality infrastructure in the future and mitigating the associated impacts on receiving waters. Combined effects of expected changes in climate and socio-economic factors on stormwater quality were examined in two urban test catchments by applying a source-based computer model (WinSLAMM) for TSS and three heavy metals (copper, lead, and zinc) for various future scenarios. Generally, both catchments showed similar responses to the future scenarios and pollutant loads were generally more sensitive to changes in socio-economic factors (i.e., increasing traffic intensities, growth and intensification of the individual land-uses) than in the climate. Specifically, for the selected Intermediate socio-economic scenario and two climate change scenarios (RSP = 2.6 and 8.5), the TSS loads from both catchments increased by about 10 % on average, but when applying the Intermediate climate change scenario (RCP = 4.5) for two SSPs, the Sustainability and Security scenarios (SSP1 and SSP3), the TSS loads increased on average by 70 %. Furthermore, it was observed that well-designed and maintained stormwater treatment facilities targeting local pollution hotspots exhibited the potential to significantly improve stormwater quality, however, at potentially high costs. In fact, it was possible to reduce pollutant loads from both catchments under the future Sustainability scenario (on average, e.g., TSS were reduced by 20 %), compared to the current conditions. The methodology developed in this study was found useful for planning climate change adaptation strategies in the context of local conditions.

Source-Based Modeling Of Urban Stormwater Quality Response to the Selected Scenarios Combining Future Changes in Climate and Socio-Economic Factors.

PubMed

Borris, Matthias; Leonhardt, Günther; Marsalek, Jiri; Österlund, Heléne; Viklander, Maria

2016-08-01

The assessment of future trends in urban stormwater quality should be most helpful for ensuring the effectiveness of the existing stormwater quality infrastructure in the future and mitigating the associated impacts on receiving waters. Combined effects of expected changes in climate and socio-economic factors on stormwater quality were examined in two urban test catchments by applying a source-based computer model (WinSLAMM) for TSS and three heavy metals (copper, lead, and zinc) for various future scenarios. Generally, both catchments showed similar responses to the future scenarios and pollutant loads were generally more sensitive to changes in socio-economic factors (i.e., increasing traffic intensities, growth and intensification of the individual land-uses) than in the climate. Specifically, for the selected Intermediate socio-economic scenario and two climate change scenarios (RSP = 2.6 and 8.5), the TSS loads from both catchments increased by about 10 % on average, but when applying the Intermediate climate change scenario (RCP = 4.5) for two SSPs, the Sustainability and Security scenarios (SSP1 and SSP3), the TSS loads increased on average by 70 %. Furthermore, it was observed that well-designed and maintained stormwater treatment facilities targeting local pollution hotspots exhibited the potential to significantly improve stormwater quality, however, at potentially high costs. In fact, it was possible to reduce pollutant loads from both catchments under the future Sustainability scenario (on average, e.g., TSS were reduced by 20 %), compared to the current conditions. The methodology developed in this study was found useful for planning climate change adaptation strategies in the context of local conditions.

Varroa destructor (Mesostigmata: Varroidae) Parasitism and Climate Differentially Influence the Prevalence, Levels, and Overt Infections of Deformed Wing Virus in Honey Bees (Hymenoptera: Apidae).

PubMed

Anguiano-Baez, Ricardo; Guzman-Novoa, Ernesto; Md Hamiduzzaman, Mollah; Espinosa-Montaño, Laura G; Correa-Benítez, Adriana

2016-01-01

The prevalence and loads of deformed wing virus (DWV) between honey bee (Apis mellifera L.) colonies from a tropical and a temperate environment were compared. The interaction between these environments and the mite Varroa destructor in relation to DWV prevalence, levels, and overt infections, was also analyzed. V. destructor rates were determined, and samples of mites, adult bees, brood parasitized with varroa mites and brood not infested by mites were analyzed. DWV was detected in 100% of the mites and its prevalence and loads in honey bees were significantly higher in colonies from the temperate climate than in colonies from the tropical climate. Significant interactions were found between climate and type of sample, with the highest levels of DWV found in varroa-parasitized brood from temperate climate colonies. Additionally, overt infections were observed only in the temperate climate. Varroa parasitism and DWV loads in bees from colonies with overt infections were significantly higher than in bees from colonies with covert infections. These results suggest that interactions between climate, V. destructor, and possibly other factors, may play a significant role in the prevalence and levels of DWV in honey bee colonies, as well as in the development of overt infections. Several hypotheses are discussed to explain these results. © The Author 2016. Published by Oxford University Press on behalf of the Entomological Society of America.

An Analytic Equation Partitioning Climate Variation and Human Impacts on River Sediment Load

NASA Astrophysics Data System (ADS)

Zhang, J.; Gao, G.; Fu, B.

2017-12-01

Spatial or temporal patterns and process-based equations could co-exist in hydrologic model. Yet, existing approaches quantifying the impacts of those variables on river sediment load (RSL) changes are found to be severely limited, and new ways to evaluate the contribution of these variables are thus needed. Actually, the Newtonian modeling is hardly achievable for this process due to the limitation of both observations and knowledge of mechanisms, whereas laws based on the Darwinian approach could provide one component of a developed hydrologic model. Since that streamflow is the carrier of suspended sediment, sediment load changes are documented in changes of streamflow and suspended sediment concentration (SSC) - water discharge relationships. Consequently, an analytic equation for river sediment load changes are proposed to explicitly quantify the relative contributions of climate variation and direct human impacts on river sediment load changes. Initially, the sediment rating curve, which is of great significance in RSL changes analysis, was decomposed as probability distribution of streamflow and the corresponding SSC - water discharge relationships at equally spaced discharge classes. Furthermore, a proposed segmentation algorithm based on the fractal theory was used to decompose RSL changes attributed to these two portions. Additionally, the water balance framework was utilized and the corresponding elastic parameters were calculated. Finally, changes in climate variables (i.e. precipitation and potential evapotranspiration) and direct human impacts on river sediment load could be figured out. By data simulation, the efficiency of the segmentation algorithm was verified. The analytic equation provides a superior Darwinian approach partitioning climate and human impacts on RSL changes, as only data series of precipitation, potential evapotranspiration and SSC - water discharge are demanded.

Good news on skylight performance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lewis, D.

1983-02-01

The effects of skylights on heating, cooling and lighting loads are examined using both winter and summer energy analysis. It is concluded that, in mild climates, skylights can save energy in summer and winter; in colder and cloudier climates, there may be a loss of energy in the winter but a savings in summer. The optimum skylight area is discussed for home and commercial applications. Glazing options (single, double, or triple), heat loss, air leakage, and condensation control are considered as well as ratio of glazing area to roof opening area, installation requirements, operation, and cleaning. An example skylight analysismore » is carried out for a Safeway supermarket in Tempe, Arizona. A list of skylight manufacturers and a source of additional information are provided. (MJJ)« less

Building America Case Study: Compact Buried Ducts in a Hot-Humid Climate House, Lady's Island, South Carolina

DOE Office of Scientific and Technical Information (OSTI.GOV)

2016-02-01

A system of compact, buried ducts provides a high-performance and cost-effective solution for delivering conditioned air throughout the building. This report outlines research activities that are expected to facilitate adoption of compact buried duct systems by builders. The results of this research would be scalable to many new house designs in most climates and markets, leading to wider industry acceptance and building code and energy program approval. The primary research question with buried ducts is potential condensation at the outer jacket of the duct insulation in humid climates during the cooling season. Current best practices for buried ducts rely onmore » encapsulating the insulated ducts with closed-cell spray polyurethane foam insulation to control condensation and improve air sealing. The encapsulated buried duct concept has been analyzed and shown to be effective in hot-humid climates. The purpose of this project is to develop an alternative buried duct system that performs effectively as ducts in conditioned space - durable, energy efficient, and cost-effective - in a hot-humid climate (IECC warm-humid climate zone 3A) with three goals that distinguish this project: 1) Evaluation of design criteria for buried ducts that use common materials and do not rely on encapsulation using spray foam or disrupt traditional work sequences, 2) Establishing design criteria for compact ducts and incorporate those with the buried duct criteria to further reduce energy losses and control installed costs, and 3) Developing HVAC design guidance for performing accurate heating and cooling load calculations for compact buried ducts.« less

Compact Buried Ducts in a Hot-Humid Climate House

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mallay, Dave

2016-01-07

"9A system of compact, buried ducts provides a high-performance and cost-effective solution for delivering conditioned air throughout the building. This report outlines research activities that are expected to facilitate adoption of compact buried duct systems by builders. The results of this research would be scalable to many new house designs in most climates and markets, leading to wider industry acceptance and building code and energy program approval. The primary research question with buried ducts is potential condensation at the outer jacket of the duct insulation in humid climates during the cooling season. Current best practices for buried ducts rely onmore » encapsulating the insulated ducts with closed-cell spray polyurethane foam insulation to control condensation and improve air sealing. The encapsulated buried duct concept has been analyzed and shown to be effective in hot-humid climates. The purpose of this project is to develop an alternative buried duct system that performs effectively as ducts in conditioned space - durable, energy efficient, and cost-effective - in a hot-humid climate (IECC warm-humid climate zone 3A) with three goals that distinguish this project: 1) Evaluation of design criteria for buried ducts that use common materials and do not rely on encapsulation using spray foam or disrupt traditional work sequences; 2) Establishing design criteria for compact ducts and incorporate those with the buried duct criteria to further reduce energy losses and control installed costs; 3) Developing HVAC design guidance for performing accurate heating and cooling load calculations for compact buried ducts.« less

Climatic controls on ecosystem resilience: Postfire regeneration in the Cape Floristic Region of South Africa.

PubMed

Wilson, Adam M; Latimer, Andrew M; Silander, John A

2015-07-21

Conservation of biodiversity and natural resources in a changing climate requires understanding what controls ecosystem resilience to disturbance. This understanding is especially important in the fire-prone Mediterranean systems of the world. The fire frequency in these systems is sensitive to climate, and recent climate change has resulted in more frequent fires over the last few decades. However, the sensitivity of postfire recovery and biomass/fuel load accumulation to climate is less well understood than fire frequency despite its importance in driving the fire regime. In this study, we develop a hierarchical statistical framework to model postfire ecosystem recovery using satellite-derived observations of vegetation as a function of stand age, topography, and climate. In the Cape Floristic Region (CFR) of South Africa, a fire-prone biodiversity hotspot, we found strong postfire recovery gradients associated with climate resulting in faster recovery in regions with higher soil fertility, minimum July (winter) temperature, and mean January (summer) precipitation. Projections using an ensemble of 11 downscaled Coupled Model Intercomparison Project Phase 5 (CMIP5) general circulation models (GCMs) suggest that warmer winter temperatures in 2080-2100 will encourage faster postfire recovery across the region, which could further increase fire frequency due to faster fuel accumulation. However, some models project decreasing precipitation in the western CFR, which would slow recovery rates there, likely reducing fire frequency through lack of fuel and potentially driving local biome shifts from fynbos shrubland to nonburning semidesert vegetation. This simple yet powerful approach to making inferences from large, remotely sensed datasets has potential for wide application to modeling ecosystem resilience in disturbance-prone ecosystems globally.

Climatic controls on ecosystem resilience: Postfire regeneration in the Cape Floristic Region of South Africa

PubMed Central

Wilson, Adam M.; Latimer, Andrew M.; Silander, John A.

2015-01-01

Conservation of biodiversity and natural resources in a changing climate requires understanding what controls ecosystem resilience to disturbance. This understanding is especially important in the fire-prone Mediterranean systems of the world. The fire frequency in these systems is sensitive to climate, and recent climate change has resulted in more frequent fires over the last few decades. However, the sensitivity of postfire recovery and biomass/fuel load accumulation to climate is less well understood than fire frequency despite its importance in driving the fire regime. In this study, we develop a hierarchical statistical framework to model postfire ecosystem recovery using satellite-derived observations of vegetation as a function of stand age, topography, and climate. In the Cape Floristic Region (CFR) of South Africa, a fire-prone biodiversity hotspot, we found strong postfire recovery gradients associated with climate resulting in faster recovery in regions with higher soil fertility, minimum July (winter) temperature, and mean January (summer) precipitation. Projections using an ensemble of 11 downscaled Coupled Model Intercomparison Project Phase 5 (CMIP5) general circulation models (GCMs) suggest that warmer winter temperatures in 2080–2100 will encourage faster postfire recovery across the region, which could further increase fire frequency due to faster fuel accumulation. However, some models project decreasing precipitation in the western CFR, which would slow recovery rates there, likely reducing fire frequency through lack of fuel and potentially driving local biome shifts from fynbos shrubland to nonburning semidesert vegetation. This simple yet powerful approach to making inferences from large, remotely sensed datasets has potential for wide application to modeling ecosystem resilience in disturbance-prone ecosystems globally. PMID:26150521

Linkages of fluvial terrace formation and geometry to Milankovitch-scale climate change revealed by the chronostratigraphy of the Colorado River above Moab, UT, and regional correlations

NASA Astrophysics Data System (ADS)

Jochems, A. P.; Pederson, J. L.

2012-12-01

Fluvial terraces are important markers that contain information about incision, deformation, and climate change in a given landscape. However, our poor understanding of the links between climate drivers and the processes behind terrace formation renders them an imprecise tool. Unresolved issues include the influence of changes in hydrology versus sediment supply in controlling incision or sedimentation, whether terraces truly can be time-correlated across a large watershed or whether this is confounded by transient sediment signals, and the process link between strath/fill terrace form and climate, tectonic, or local valley geometry controls. In terms of the latter issue, terrace type is commonly associated with climate or tectonic controls, and it has been suggested that fill terraces tend to form in bedrock-restricted reaches and strath terraces in broader valleys. We address these problems through detailed chronostratigraphy of Colorado River terraces upstream of Moab, UT, and correlations to similarly well-constrained records near Green River, UT, and eastern Grand Canyon. Along the Colorado profile upstream of Moab, there are four traceable late Pleistocene mainstem terraces we designate as M2, M3y (younger), M3, and M4. Optically stimulated luminescence (OSL) ages indicate sedimentation at 25-20 ka, 50-40 ka, 75-60 ka, and 115-85 ka, respectively, for these deposits. Importantly, results indicate synchronous timing of terrace formation across the Colorado Plateau, ruling out transient sediment signals as a factor. Sedimentation of the M2 and M3 occur during the build-up to and height of glaciations, but the M3y and M4 are instead deposited during episodes of highly variable climate during marine isotope stages (MIS) 3 and 5. Incision notably occurs during interglacials or at least periods of low ice volume. In the Colorado Plateau, we suggest terrace sedimentation is linked to anemic peak flows during full glacial conditions (M2 and M3), but major terrace deposits also form during pulses of dryland tributary sediment loading with markedly different timing (M3y and M4). Conversely, we suggest incision is driven by higher peak flows, such as during the current interglacial. In terms of strath/fill geometry, the spatial patterns of terraces in the study area rule out any simple climate versus tectonic relationship. Rather, local canyon geometry, bedrock resistance, and neotectonics control terrace form. For example, thick (7-13 m) fill terraces are unexpectedly found in broad Professor Valley, whereas thin (2-3 m) strath terraces are found in the canyon upstream. Long-profile survey data show that terraces may exhibit warping on the flanks of the Cache Valley graben and other potentially active salt tectonic features of the Paradox Basin. This and variations in local bedrock properties obfuscate any climate-related information within terrace form itself. In summary, Colorado River terraces were formed in response to glacial-interglacial hydrology changes in the headwaters and also during different periods of increased local sediment loading from the plateau drylands. Terrace form is not simply related to regional climate or tectonics, but instead to variable local valley geometry and neotectonics.

North–south polarization of European electricity consumption under future warming

PubMed Central

Wenz, Leonie; Levermann, Anders; Auffhammer, Maximilian

2017-01-01

There is growing empirical evidence that anthropogenic climate change will substantially affect the electric sector. Impacts will stem both from the supply side—through the mitigation of greenhouse gases—and from the demand side—through adaptive responses to a changing environment. Here we provide evidence of a polarization of both peak load and overall electricity consumption under future warming for the world’s third-largest electricity market—the 35 countries of Europe. We statistically estimate country-level dose–response functions between daily peak/total electricity load and ambient temperature for the period 2006–2012. After removing the impact of nontemperature confounders and normalizing the residual load data for each country, we estimate a common dose–response function, which we use to compute national electricity loads for temperatures that lie outside each country’s currently observed temperature range. To this end, we impose end-of-century climate on today’s European economies following three different greenhouse-gas concentration trajectories, ranging from ambitious climate-change mitigation—in line with the Paris agreement—to unabated climate change. We find significant increases in average daily peak load and overall electricity consumption in southern and western Europe (∼3 to ∼7% for Portugal and Spain) and significant decreases in northern Europe (∼−6 to ∼−2% for Sweden and Norway). While the projected effect on European total consumption is nearly zero, the significant polarization and seasonal shifts in peak demand and consumption have important ramifications for the location of costly peak-generating capacity, transmission infrastructure, and the design of energy-efficiency policy and storage capacity. PMID:28847939

North-south polarization of European electricity consumption under future warming.

PubMed

Wenz, Leonie; Levermann, Anders; Auffhammer, Maximilian

2017-09-19

There is growing empirical evidence that anthropogenic climate change will substantially affect the electric sector. Impacts will stem both from the supply side-through the mitigation of greenhouse gases-and from the demand side-through adaptive responses to a changing environment. Here we provide evidence of a polarization of both peak load and overall electricity consumption under future warming for the world's third-largest electricity market-the 35 countries of Europe. We statistically estimate country-level dose-response functions between daily peak/total electricity load and ambient temperature for the period 2006-2012. After removing the impact of nontemperature confounders and normalizing the residual load data for each country, we estimate a common dose-response function, which we use to compute national electricity loads for temperatures that lie outside each country's currently observed temperature range. To this end, we impose end-of-century climate on today's European economies following three different greenhouse-gas concentration trajectories, ranging from ambitious climate-change mitigation-in line with the Paris agreement-to unabated climate change. We find significant increases in average daily peak load and overall electricity consumption in southern and western Europe (∼3 to ∼7% for Portugal and Spain) and significant decreases in northern Europe (∼-6 to ∼-2% for Sweden and Norway). While the projected effect on European total consumption is nearly zero, the significant polarization and seasonal shifts in peak demand and consumption have important ramifications for the location of costly peak-generating capacity, transmission infrastructure, and the design of energy-efficiency policy and storage capacity.

Sediment load trends in the Magdalena River basin (1980-2010): Anthropogenic and climate-induced causes

NASA Astrophysics Data System (ADS)

Restrepo, Juan D.; Escobar, Heber A.

2018-02-01

The Colombian Andes and its main river basin, the Magdalena, have witnessed dramatic changes in land cover and further forest loss during the last three decades. For the Magdalena River, human activities appear to have played a more prominent role compared to rainfall (climate change) to mobilize sediment. However, environmental authorities in Colombia argue that climate change is the main trigger of erosion and floods experienced during the last decade. Here we present the first regional exercise addressing the following: (1) what are the observed trends of sediment load in the northern Andes during the last three decades? and (2) are sediment load trends in agreement with tendencies in land use change and climate (e.g., precipitation)? We perform Mann-Kendall tests on sediment load series for 21 main tributary systems during the 1980-2010 period. These gauging stations represent 77% of the whole Magdalena basin area. The last decade has been a period of increased pulses in sediment transport as seen by the statistical significant trends in load. Overall, six subcatchments, representing 55% of the analyzed Magdalena basin area, have witnessed increasing trends in sediment load. Also, some major tributaries have experienced changes in their interannual mean sediment flux during the mid- 1990s and 2005. Further analysis of land cover change (e.g., deforestation) indicates that the basin has undergone considerable change. Forest cover decreased by 40% over the period of study, while the area under agriculture and pasture cover (agricultural lands 1 and 2) increased by 65%. The highest peak of forest loss on record in the Magdalena basin, 5106 km2 or 24% of the combined deforestation in Colombia, occurred during the 2005-2010 period. In contrast, Mann-Kendall tests on rainfall series for 61 stations reveal that precipitation shows no regional signs of increasing trends. Also, increasing trends in sediment load match quite well with the marked increase in forest clearance during the 1990-2000 and 2005-2010 periods. Such signs of increasing sediment fluxes should not be attributed to climate change and rainfall variability alone. As a whole, the Magdalena, one of the top 10 rivers in terms of sediment delivery to the ocean (184 Mt y- 1), and its tributaries have experienced increasing trends in sediment load during the 1980-2010 period; increases in close agreement with trends in land use change and deforestation. During the last decade, the Magdalena River drainage basin has witnessed an increase in erosion rates of 34%, from 550 t km- 2 y- 1 before 2000 to 710 t km- 2 y- 1 for the 2000-2010 period, and the average sediment load for the whole basin increased to 44 Mt y- 1 for the same period. Similar to the global picture of human contribution to sediment generation, the rate of anthropogenic soil erosion in the Magdalena basin probably exceeds the rate of climate-driven erosion by several orders of magnitude.

Effects of climate change and wildfire on soil loss in the Southern Rockies Ecoregion

Treesearch

S. E. Litschert; D. M. Theobald; T. C. Brown

2014-01-01

Forests in the Southern Rockies Ecoregion surround the headwaters of several major rivers in the western and central US. Future climatic changes will increase the incidence of wildfire in those forests, and will likely lead to changes in downstream water quality, including sediment loads.We estimated soil loss under the historic climate and two IPCC climate change...

Abrupt transitions of the top-down controlled Black Sea pelagic ecosystem during 1960 2000: Evidence for regime-shifts under strong fishery exploitation and nutrient enrichment modulated by climate-induced variations

NASA Astrophysics Data System (ADS)

Oguz, Temel; Gilbert, Denis

2007-02-01

Functioning of the Black Sea ecosystem has profoundly changed since the early 1970s under cumulative effects of excessive nutrient enrichment, strong cooling/warming, over-exploitation of pelagic fish stocks, and population outbreak of gelatinous carnivores. Applying a set of criteria to the long-term (1960-2000) ecological time-series data, the present study demonstrates that the Black Sea ecosystem was reorganised during this transition phase in different forms of top-down controlled food web structure through successive regime-shifts of distinct ecological properties. The Secchi disc depth, oxic-anoxic interface zone, dissolved oxygen and hydrogen sulphide concentrations also exhibit abrupt transition between their alternate regimes, and indicate tight coupling between the lower trophic food web structure and the biogeochemical pump in terms of regime-shift events. The first shift, in 1973-1974, marks a switch from large predatory fish to small planktivore fish-controlled system, which persisted until 1989 in the form of increasing small pelagic and phytoplankton biomass and decreasing zooplankton biomass. The increase in phytoplankton biomass is further supported by a bottom-up contribution due to the cumulative response to high anthropogenic nutrient load and the concurrent shift of the physical system to the "cold climate regime" following its ˜20-year persistence in the "warm climate regime". The end of the 1980s signifies the depletion of small planktivores and the transition to a gelatinous carnivore-controlled system. By the end of the 1990s, small planktivore populations take over control of the system again. Concomitantly, their top-down pressure when combined with diminishing anthropogenic nutrient load and more limited nutrient supply into the surface waters due to stabilizing effects of relatively warm winter conditions switched the "high production" regime of phytoplankton to its background "low production" regime. The Black Sea regime-shifts appear to be sporadic events forced by strong transient decadal perturbations, and therefore differ from the multi-decadal scale cyclical events observed in pelagic ocean ecosystems under low-frequency climatic forcing. The Black Sea observations illustrate that eutrophication and extreme fishery exploitation can indeed induce hysteresis in large marine ecosystems, when they can exert sufficiently strong forcing onto the system. They further illustrate the link between the disruption of the top predators, proliferation of new predator stocks, and regime-shift events. Examples of these features have been reported for some aquatic ecosystems, but are extremely limited for large marine ecosystems.

Thermal Performance of Vegetative Roofing Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Desjarlais, Andre Omer; Zaltash, Abdolreza; Atchley, Jerald Allen

2010-01-01

Vegetative roofing, otherwise known as green or garden roofing, has seen tremendous growth in the last decade in the United States. The numerous benefits that green roofs provide have helped to fuel their resurgence in industrial and urban settings. There are many environmental and economical benefits that can be realized by incorporating a vegetative roof into the design of a building. These include storm-water retention, energy conservation, reduction in the urban heat island effect, increased longevity of the roofing membrane, the ability of plants to create biodiversity and filter air contaminants, and beautification of the surroundings by incorporating green space.more » The vegetative roof research project at Oak Ridge National Laboratory (ORNL) was initiated to quantify the thermal performance of various vegetative roofing systems relative to black and white roofs. Single Ply Roofing Institute (SPRI) continued its long-term commitment to cooperative research with ORNL in this project. Low-slope roof systems for this study were constructed and instrumented for continuous monitoring in the mixed climate of East Tennessee. This report summarizes the results of the annual cooling and heating loads per unit area of three vegetative roofing systems with side-by-side comparison to black and white roofing systems as well as a test section with just the growing media without plants. Results showed vegetative roofs reduced heat gain (reduced cooling loads) compared to the white control system due to the thermal mass, extra insulation, and evapo-transpiration associated with the vegetative roofing systems. The 4-inch and tray systems reduced the heat gain by approximately 61%, while the reduction with the 8-inch vegetative roof was found to be approximately 67%. The vegetative roofing systems were more effective in reducing heat gain than in reducing heat losses (heating loads). The reduction in heat losses for the 4-inch and tray systems were found to be approximately 40% in the mixed climate of East Tennessee. It should be noted that these values are climate dependent. Vegetative roofs also reduced the temperature (heat exposure) and temperature fluctuations (thermal stress) experienced by the membrane. In the cooling season of East Tennessee, the average peak temperature of the 4-inch and tray systems was found to be approximately 94 F cooler than the control black roofing system. The average temperature fluctuations at the membrane for the 4-inch and tray systems were found to be approximately 10 F compared to 125 F for black and 64 F for white systems. As expected, the 8-inch vegetative roof had the lowest fluctuations at approximately 2 F. Future work will include modeling of the energy performance of vegetative roof panels in the test climate of East Tennessee. The validated model then will be used to predict energy use in roofs with different insulation levels and in climates different from the test climate.« less

Response of non-point source pollutant loads to climate change in the Shitoukoumen reservoir catchment.

PubMed

Zhang, Lei; Lu, Wenxi; An, Yonglei; Li, Di; Gong, Lei

2012-01-01

The impacts of climate change on streamflow and non-point source pollutant loads in the Shitoukoumen reservoir catchment are predicted by combining a general circulation model (HadCM3) with the Soil and Water Assessment Tool (SWAT) hydrological model. A statistical downscaling model was used to generate future local scenarios of meteorological variables such as temperature and precipitation. Then, the downscaled meteorological variables were used as input to the SWAT hydrological model calibrated and validated with observations, and the corresponding changes of future streamflow and non-point source pollutant loads in Shitoukoumen reservoir catchment were simulated and analyzed. Results show that daily temperature increases in three future periods (2010-2039, 2040-2069, and 2070-2099) relative to a baseline of 1961-1990, and the rate of increase is 0.63°C per decade. Annual precipitation also shows an apparent increase of 11 mm per decade. The calibration and validation results showed that the SWAT model was able to simulate well the streamflow and non-point source pollutant loads, with a coefficient of determination of 0.7 and a Nash-Sutcliffe efficiency of about 0.7 for both the calibration and validation periods. The future climate change has a significant impact on streamflow and non-point source pollutant loads. The annual streamflow shows a fluctuating upward trend from 2010 to 2099, with an increase rate of 1.1 m(3) s(-1) per decade, and a significant upward trend in summer, with an increase rate of 1.32 m(3) s(-1) per decade. The increase in summer contributes the most to the increase of annual load compared with other seasons. The annual NH (4) (+) -N load into Shitoukoumen reservoir shows a significant downward trend with a decrease rate of 40.6 t per decade. The annual TP load shows an insignificant increasing trend, and its change rate is 3.77 t per decade. The results of this analysis provide a scientific basis for effective support of decision makers and strategies of adaptation to climate change.

Assessing the impacts of future climate conditions on the effectiveness of winter cover crops in reducing nitrate loads into the Chesapeake Bay Watershed using SWAT model

USGS Publications Warehouse

Lee, Sangchul; Sadeghi, Ali M.; Yeo, In-Young; McCarty, Gregory W.; Hively, W. Dean

2017-01-01

Winter cover crops (WCCs) have been widely implemented in the Coastal Plain of the Chesapeake Bay watershed (CBW) due to their high effectiveness at reducing nitrate loads. However, future climate conditions (FCCs) are expected to exacerbate water quality degradation in the CBW by increasing nitrate loads from agriculture. Accordingly, the question remains whether WCCs are sufficient to mitigate increased nutrient loads caused by FCCs. In this study, we assessed the impacts of FCCs on WCC nitrate reduction efficiency on the Coastal Plain of the CBW using Soil and Water Assessment Tool (SWAT) model. Three FCC scenarios (2085 – 2098) were prepared using General Circulation Models (GCMs), considering three Intergovernmnental Panel on Climate Change (IPCC) Special Report on Emissions Scenarios (SRES) greenhouse gas emission scenarios. We also developed six representative WCC implementation scenarios based on the most commonly used planting dates and species of WCCs in this region. Simulation results showed that WCC biomass increased by ~ 58 % under FCC scenarios, due to climate conditions conducive to the WCC growth. Prior to implementing WCCs, annual nitrate loads increased by ~ 43 % under FCC scenarios compared to the baseline scenario (2001 – 2014). When WCCs were planted, annual nitrate loads were substantially reduced by ~ 48 % and WCC nitrate reduction efficiency water ~ 5 % higher under FCC scenarios relative to the baseline. The increase rate of WCC nitrate reduction efficiency varied by FCC scenarios and WCC planting methods. As CO2 concentration was higher and winters were warmer under FCC scenarios, WCCs had greater biomass and therefore showed higher nitrate reduction efficiency. In response to FCC scenarios, the performance of less effective WCC practices (e.g., barley, wheat, and late planting) under the baseline indicated ~ 14 % higher increase rate of nitrate reduction efficiency compared to ones with better effectiveness under the baseline (e.g., rye and early planting), due to warmer temperatures. According to simulation results, WCCs were effective to mitigate nitrate loads accelerated by FCCs and therefore the role of WCCs in mitigating nitrate loads is even more important in the given FCCs.

Landscape genomic analysis of candidate genes for climate adaptation in a California endemic oak, Quercus lobata.

PubMed

Sork, Victoria L; Squire, Kevin; Gugger, Paul F; Steele, Stephanie E; Levy, Eric D; Eckert, Andrew J

2016-01-01

The ability of California tree populations to survive anthropogenic climate change will be shaped by the geographic structure of adaptive genetic variation. Our goal is to test whether climate-associated candidate genes show evidence of spatially divergent selection in natural populations of valley oak, Quercus lobata, as preliminary indication of local adaptation. Using DNA from 45 individuals from 13 localities across the species' range, we sequenced portions of 40 candidate genes related to budburst/flowering, growth, osmotic stress, and temperature stress. Using 195 single nucleotide polymorphisms (SNPs), we estimated genetic differentiation across populations and correlated allele frequencies with climate gradients using single-locus and multivariate models. The top 5% of FST estimates ranged from 0.25 to 0.68, yielding loci potentially under spatially divergent selection. Environmental analyses of SNP frequencies with climate gradients revealed three significantly correlated SNPs within budburst/flowering genes and two SNPs within temperature stress genes with mean annual precipitation, after controlling for multiple testing. A redundancy model showed a significant association between SNPs and climate variables and revealed a similar set of SNPs with high loadings on the first axis. In the RDA, climate accounted for 67% of the explained variation, when holding climate constant, in contrast to a putatively neutral SSR data set where climate accounted for only 33%. Population differentiation and geographic gradients of allele frequencies in climate-associated functional genes in Q. lobata provide initial evidence of adaptive genetic variation and background for predicting population response to climate change. © 2016 Botanical Society of America.

Farmland-atmosphere feedbacks amplify decreases in diffuse nitrogen pollution in a freeze-thaw agricultural area under climate warming conditions.

PubMed

Gao, Xiang; Ouyang, Wei; Hao, Zengchao; Shi, Yandan; Wei, Peng; Hao, Fanghua

2017-02-01

Although climate warming and agricultural land use changes are two of the primary instigators of increased diffuse pollution, they are usually considered separately or additively. This likely lead to poor decisions regarding climate adaptation. Climate warming and farmland responses have synergistic consequences for diffuse nitrogen pollution, which are hypothesized to present different spatio-temporal patterns. In this study, we propose a modeling framework to simulate the synergistic impacts of climate warming and warming-induced farmland shifts on diffuse pollution. Active accumulated temperature response for latitudinal and altitudinal directions was predicted based on a simple agro-climate model under different temperature increments (△T 0 is from 0.8°C to 1.4°C at an interval of 0.2°C). Spatial distributions of dryland shift to paddy land were determined by considering accumulated temperature. Different temperature increments and crop distributions were inserted into Soil and Water Assessment Tool model, which quantified the spatio-temporal changes of nitrogen. Warming led to a decrease of the annual total nitrogen loading (2.6%-14.2%) in the low latitudes compared with baseline, which was larger than the decrease (0.8%-6.2%) in the high latitudes. The synergistic impacts amplified the decrease of the loading in the low and high latitudes at the sub-basin scale. Warming led to a decrease of the loading at a rate of 0.35kg/ha/°C, which was lower than the synergistic impacts (3.67kg/ha/°C) at the watershed level. However, warming led to the slight increase of the annual averaged NO3 (LAT) (0.16kg/ha/°C), which was amplified by the synergistic impacts (0.22kg/ha/°C). Expansion of paddy fields led to a decrease in the monthly total nitrogen loading throughout the year, but amplified an increase in the loading in August and September. The decreased response in spatio-temporal nitrogen patterns is substantially amplified by farmland-atmosphere feedbacks associated with farmland shifts in response to warming. Copyright © 2016 Elsevier B.V. All rights reserved.

Comparative analyses of hydrological responses of two adjacent watersheds to climate variability and change using the SWAT model

NASA Astrophysics Data System (ADS)

Lee, Sangchul; Yeo, In-Young; Sadeghi, Ali M.; McCarty, Gregory W.; Hively, Wells D.; Lang, Megan W.; Sharifi, Amir

2018-01-01

Water quality problems in the Chesapeake Bay Watershed (CBW) are expected to be exacerbated by climate variability and change. However, climate impacts on agricultural lands and resultant nutrient loads into surface water resources are largely unknown. This study evaluated the impacts of climate variability and change on two adjacent watersheds in the Coastal Plain of the CBW, using the Soil and Water Assessment Tool (SWAT) model. We prepared six climate sensitivity scenarios to assess the individual impacts of variations in CO2 concentration (590 and 850 ppm), precipitation increase (11 and 21 %), and temperature increase (2.9 and 5.0 °C), based on regional general circulation model (GCM) projections. Further, we considered the ensemble of five GCM projections (2085-2098) under the Representative Concentration Pathway (RCP) 8.5 scenario to evaluate simultaneous changes in CO2, precipitation, and temperature. Using SWAT model simulations from 2001 to 2014 as a baseline scenario, predicted hydrologic outputs (water and nitrate budgets) and crop growth were analyzed. Compared to the baseline scenario, a precipitation increase of 21 % and elevated CO2 concentration of 850 ppm significantly increased streamflow and nitrate loads by 50 and 52 %, respectively, while a temperature increase of 5.0 °C reduced streamflow and nitrate loads by 12 and 13 %, respectively. Crop biomass increased with elevated CO2 concentrations due to enhanced radiation- and water-use efficiency, while it decreased with precipitation and temperature increases. Over the GCM ensemble mean, annual streamflow and nitrate loads showed an increase of ˜ 70 % relative to the baseline scenario, due to elevated CO2 concentrations and precipitation increase. Different hydrological responses to climate change were observed from the two watersheds, due to contrasting land use and soil characteristics. The watershed with a larger percent of croplands demonstrated a greater increased rate of 5.2 kg N ha-1 in nitrate yield relative to the watershed with a lower percent of croplands as a result of increased export of nitrate derived from fertilizer. The watershed dominated by poorly drained soils showed increased nitrate removal due do enhanced denitrification compared to the watershed dominated by well-drained soils. Our findings suggest that increased implementation of conservation practices would be necessary for this region to mitigate increased nitrate loads associated with predicted changes in future climate.

Comparative study of control strategies for hybrid GSHP system in the cooling dominated climate

DOE PAGES

Wang, Shaojie; Liu, Xiaobing; Gates, Steve

2015-01-06

The ground source heat pump (GSHP) system is one of the most energy efficient HVAC technologies in the current market. However, the heat imbalance may degrade the ability of the ground loop heat exchanger (GLHX) to absorb or reject heat. The hybrid GSHP system, which combines a geothermal well field with a supplemental boiler or cooling tower, can balance the loads imposed on the ground loop heat exchangers to minimize its size while retaining superior energy efficiency. This paper presents a recent simulation-based study with an intention to compare multiple common control strategies used in hybrid GSHP systems, including fixedmore » setpoint, outside air reset, load reset, and wetbulb reset. A small office in Oklahoma City conditioned by a hybrid GSHP system was simulated with the latest version of eQUEST 3.7 [1]. In the end, the simulation results reveal that the hybrid GSHP system has the excellent capability to meet the cooling and heating setpoints during the occupied hours, balance thermal loads on the ground loop, as well as improve the thermal comfort of the occupants with the reduced size well field.« less

Evaluating water quality ecosystem services of wetlands under historic and future climate

NASA Astrophysics Data System (ADS)

Records, R.; Arabi, M.; Fassnacht, S. R.; Duffy, W.; Ahmadi, M.; Hegewisch, K.

2013-12-01

Potential hydrologic effects of climate change have been assessed extensively; however, possible impacts of changing climate on in-stream water quality at the watershed scale have received little study. We assessed potential impacts of climate change on water quantity and quality in the mountainous Sprague River watershed, Oregon, USA, where high total phosphorus (TP) and sediment loads are associated with lake eutrophication and mortality of endangered fish species. Additionally, we analyzed water quality impacts of wetland and riparian zone loss and gain under present-day climate and future climate scenarios. We utilized the hydrologic model Soil and Water Assessment Tool (SWAT) forced with six distinct climate scenarios derived from Coupled Model Intercomparison Project 5 (CMIP5) General Circulation Models to assess magnitude and direction of trends in streamflow, sediment and TP fluxes in the mid-21st century (2030-2059). Model results showed little significant trend in average annual streamflow under most climate scenarios, but trends in annual and monthly streamflow, sediment, and TP fluxes were more pronounced and were generally increasing. Results also suggest that future loss of present-day wetlands and riparian zones under land use or climatic change could result in substantial increases in sediment and TP loads at the Sprague River outlet.

Temporal responses of coastal hypoxia to nutrient loading and physical controls

NASA Astrophysics Data System (ADS)

Kemp, W. M.; Testa, J. M.; Conley, D. J.; Gilbert, D.; Hagy, J. D.

2009-12-01

The incidence and intensity of hypoxic waters in coastal aquatic ecosystems has been expanding in recent decades coincident with eutrophication of the coastal zone. Worldwide, there is strong interest in reducing the size and duration of hypoxia in coastal waters, because hypoxia causes negative effects for many organisms and ecosystem processes. Although strategies to reduce hypoxia by decreasing nutrient loading are predicated on the assumption that this action would reverse eutrophication, recent analyses of historical data from European and North American coastal systems suggest little evidence for simple linear response trajectories. We review published parallel time-series data on hypoxia and loading rates for inorganic nutrients and labile organic matter to analyze trajectories of oxygen (O2) response to nutrient loading. We also assess existing knowledge of physical and ecological factors regulating O2 in coastal marine waters to facilitate analysis of hypoxia responses to reductions in nutrient (and/or organic matter) inputs. Of the 24 systems identified where concurrent time series of loading and O2 were available, half displayed relatively clear and direct recoveries following remediation. We explored in detail 5 well-studied systems that have exhibited complex, non-linear responses to variations in loading, including apparent "regime shifts". A summary of these analyses suggests that O2 conditions improved rapidly and linearly in systems where remediation focused on organic inputs from sewage treatment plants, which were the primary drivers of hypoxia. In larger more open systems where diffuse nutrient loads are more important in fueling O2 depletion and where climatic influences are pronounced, responses to remediation tended to follow non-linear trends that may include hysteresis and time-lags. Improved understanding of hypoxia remediation requires that future studies use comparative approaches and consider multiple regulating factors. These analyses should consider: (1) the dominant temporal scales of the hypoxia, (2) the relative contributions of inorganic and organic nutrients, (3) the influence of shifts in climatic and oceanographic processes, and (4) the roles of feedback interactions whereby O2-sensitive biogeochemistry, trophic interactions, and habitat conditions influence the nutrient and algal dynamics that regulate O2 levels.

Climate Considerations Of The Electricity Supply Systems In Industries

NASA Astrophysics Data System (ADS)

Asset, Khabdullin; Zauresh, Khabdullina

2014-12-01

The study is focused on analysis of climate considerations of electricity supply systems in a pellet industry. The developed analysis model consists of two modules: statistical data of active power losses evaluation module and climate aspects evaluation module. The statistical data module is presented as a universal mathematical model of electrical systems and components of industrial load. It forms a basis for detailed accounting of power loss from the voltage levels. On the basis of the universal model, a set of programs is designed to perform the calculation and experimental research. It helps to obtain the statistical characteristics of the power losses and loads of the electricity supply systems and to define the nature of changes in these characteristics. Within the module, several methods and algorithms for calculating parameters of equivalent circuits of low- and high-voltage ADC and SD with a massive smooth rotor with laminated poles are developed. The climate aspects module includes an analysis of the experimental data of power supply system in pellet production. It allows identification of GHG emission reduction parameters: operation hours, type of electrical motors, values of load factor and deviation of standard value of voltage.

Climate change impacts on forest soil critical acid loads and exceedances at a national scale

Treesearch

Steven G. McNulty; Erika C. Cohen; Jennifer A. Moore Myers

2013-01-01

Federal agencies are currently developing guidelines for forest soil critical acid loads across the United States. A critical acid load is defined as the amount of acid deposition (usually expressed on an annual basis) that an ecosystem can absorb. Traditionally, an ecosystem is considered to be at risk for health impairment when the critical acid load exceeds a level...

Suspended sediment load in northwestern South America (Colombia): A new view on variability and fluxes into the Caribbean Sea

NASA Astrophysics Data System (ADS)

Restrepo López, Juan Camilo; Orejarena R, Andrés F.; Torregroza, Ana Carolina

2017-12-01

Monthly averaged suspended sediment load data from seven rivers in northern Colombia (Caribbean alluvial plain) draining into the Caribbean Sea were analyzed to quantify magnitudes, estimate long-term trends, and evaluate variability patterns of suspended sediment load. Collectively these rivers deliver an average of around 146.3 × 106 t yr-1 of suspended sediments to the Colombian Caribbean coast. The largest sediment supply is provided by the Magdalena River, with a mean suspended sediment load of 142.6 × 106 t yr-1, or 38% of the total fluvial discharge estimated for the whole Caribbean littoral zone. Between 2000 and 2010, the annual suspended sediment load of these rivers increased by as much as 36%. Wavelet spectral analyses identified periods of intense variability between 1987-1990 and 1994-2002, where major oscillation processes appeared simultaneously. The semi-annual, annual and quasi-decadal bands are the main factors controlling suspended sediment load variability in fluvial systems, whereas the quasi-biennial and interannual bands constitute second-order sources of variability. The climatic and oceanographic drivers of the oscillations identified through wavelet spectral analyses define a signal of medium-long-term variability for the suspended sediment load, while the physiographic and environmental characteristics of the basins determine their ability to magnify, attenuate or modify this signal.

Modeling the influence of climate change on watershed systems: Adaptation through targeted practices

NASA Astrophysics Data System (ADS)

Dudula, John; Randhir, Timothy O.

2016-10-01

Climate change may influence hydrologic processes of watersheds (IPCC, 2013) and increased runoff may cause flooding, eroded stream banks, widening of stream channels, increased pollutant loading, and consequently impairment of aquatic life. The goal of this study was to quantify the potential impacts of climate change on watershed hydrologic processes and to evaluate scale and effectiveness of management practices for adaptation. We simulate baseline watershed conditions using the Hydrological Simulation Program Fortran (HSPF) simulation model to examine the possible effects of changing climate on watershed processes. We also simulate the effects of adaptation and mitigation through specific best management strategies for various climatic scenarios. With continuing low-flow conditions and vulnerability to climate change, the Ipswich watershed is the focus of this study. We quantify fluxes in runoff, evapotranspiration, infiltration, sediment load, and nutrient concentrations under baseline and climate change scenarios (near and far future). We model adaptation options for mitigating climate effects on watershed processes using bioretention/raingarden Best Management Practices (BMPs). It was observed that climate change has a significant impact on watershed runoff and carefully designed and maintained BMPs at subwatershed scale can be effective in mitigating some of the problems related to stormwater runoff. Policy options include implementation of BMPs through education and incentives for scale-dependent and site specific bioretention units/raingardens to increase the resilience of the watershed system to current and future climate change.

Quantitative Assessment of Temperature Sensitivity of the South Fork Nooksack River under Future Climates using QUAL2Kw

EPA Science Inventory

The Total Maximum Daily Load (TMDL) program, established by the Clean Water Act, is used to establish limits on loading of pollutants from point and nonpoint sources necessary to achieve water quality standards. One important use of a temperature TMDL is to allocate thermal loads...

Integrative Analysis of Desert Dust Size and Abundance Suggests Less Dust Climate Cooling

NASA Technical Reports Server (NTRS)

Kok, Jasper F.; Ridley, David A.; Zhou, Qing; Miller, Ron L.; Zhao, Chun; Heald, Colette L.; Ward, Daniel S.; Albani, Samuel; Haustein, Karsten

2017-01-01

Desert dust aerosols affect Earths global energy balance through interactions with radiation, clouds, and ecosystems. But the magnitudes of these effects are so uncertain that it remains unclear whether atmospheric dust has a net warming or cooling effect on global climate. Consequently, it is still uncertain whether large changes in atmospheric dust loading over the past century have slowed or accelerated anthropogenic climate change, and the climate impact of possible future alterations in dust loading is similarly disputed. Here we use an integrative analysis of dust aerosol sizes and abundance to constrain the climatic impact of dust through direct interactions with radiation. Using a combination of observational, experimental, and model data, we find that atmospheric dust is substantially coarser than represented in current climate models. Since coarse dust warms global climate, the dust direct radiative effect (DRE) is likely less cooling than the 0.4 W m superscript 2 estimated by models in a current ensemble. We constrain the dust DRE to -0.20 (-0.48 to +0.20) W m superscript 2, which suggests that the dust DRE produces only about half the cooling that current models estimate, and raises the possibility that dust DRE is actually net warming the planet.

Global warming and ocean stratification: A potential result of large extraterrestrial impacts

NASA Astrophysics Data System (ADS)

Joshi, Manoj; von Glasow, Roland; Smith, Robin S.; Paxton, Charles G. M.; Maycock, Amanda C.; Lunt, Daniel J.; Loptson, Claire; Markwick, Paul

2017-04-01

The prevailing paradigm for the climatic effects of large asteroid or comet impacts is a reduction in sunlight and significant short-term cooling caused by atmospheric aerosol loading. Here we show, using global climate model experiments, that the large increases in stratospheric water vapor that can occur upon impact with the ocean cause radiative forcings of over +20 W m-2 in the case of 10 km sized bolides. The result of such a positive forcing is rapid climatic warming, increased upper ocean stratification, and potentially disruption of upper ocean ecosystems. Since two thirds of the world's surface is ocean, we suggest that some bolide impacts may actually warm climate overall. For impacts producing both stratospheric water vapor and aerosol loading, radiative forcing by water vapor can reduce or even cancel out aerosol-induced cooling, potentially causing 1-2 decades of increased temperatures in both the upper ocean and on the land surface. Such a response, which depends on the ratio of aerosol to water vapor radiative forcing, is distinct from many previous scenarios for the climatic effects of large bolide impacts, which mostly account for cooling from aerosol loading. Finally, we discuss how water vapor forcing from bolide impacts may have contributed to two well-known phenomena: extinction across the Cretaceous/Paleogene boundary and the deglaciation of the Neoproterozoic snowball Earth.

Efficient Formation of Stratospheric Aerosol for Climate Engineering by Emission of Condensible Vapor from Aircraft

NASA Technical Reports Server (NTRS)

Pierce, Jeffrey R.; Weisenstein, Debra K.; Heckendorn, Patricia; Peter. Thomas; Keith, David W.

2010-01-01

Recent analysis suggests that the effectiveness of stratospheric aerosol climate engineering through emission of non-condensable vapors such as SO2 is limited because the slow conversion to H2SO4 tends to produce aerosol particles that are too large; SO2 injection may be so inefficient that it is difficult to counteract the radiative forcing due to a CO2 doubling. Here we describe an alternate method in which aerosol is formed rapidly in the plume following injection of H2SO4, a condensable vapor, from an aircraft. This method gives better control of particle size and can produce larger radiative forcing with lower sulfur loadings than SO2 injection. Relative to SO2 injection, it may reduce some of the adverse effects of geoengineering such as radiative heating of the lower stratosphere. This method does not, however, alter the fact that such a geoengineered radiative forcing can, at best, only partially compensate for the climate changes produced by CO2.

Modeling the effects of climatic and land use changes on phytoplankton and water quality of the largest Turkish freshwater lake: Lake Beyşehir.

PubMed

Bucak, Tuba; Trolle, Dennis; Tavşanoğlu, Ü Nihan; Çakıroğlu, A İdil; Özen, Arda; Jeppesen, Erik; Beklioğlu, Meryem

2018-04-15

Climate change and intense land use practices are the main threats to ecosystem structure and services of Mediterranean lakes. Therefore, it is essential to predict the future changes and develop mitigation measures to combat such pressures. In this study, Lake Beyşehir, the largest freshwater lake in the Mediterranean basin, was selected to study the impacts of climate change and various land use scenarios on the ecosystem dynamics of Mediterranean freshwater ecosystems and the services that they provide. For this purpose, we linked catchment model outputs to the two different processed-based lake models: PCLake and GLM-AED, and tested the scenarios of five General Circulation Models, two Representation Concentration Pathways and three different land use scenarios, which enable us to consider the various sources of uncertainty. Climate change and land use scenarios generally predicted strong future decreases in hydraulic and nutrient loads from the catchment to the lake. These changes in loads translated into alterations in water level as well as minor changes in chlorophyll a (Chl-a) concentrations. We also observed an increased abundance of cyanobacteria in both lake models. Total phosphorus, temperature and hydraulic loading were found to be the most important variables determining cyanobacteria biomass. As the future scenarios revealed only minor changes in Chl-a due to the significant decrease in nutrient loads, our results highlight that reduced nutrient loading in a warming world may play a crucial role in offsetting the effects of temperature on phytoplankton growth. However, our results also showed increased abundance of cyanobacteria in the future may threaten ecosystem integrity and may limit drinking water ecosystem services. In addition, extended periods of decreased hydraulic loads from the catchment and increased evaporation may lead to water level reductions and may diminish the ecosystem services of the lake as a water supply for irrigation and drinking water. Copyright © 2017 Elsevier B.V. All rights reserved.

Quantitative Assessment of Temperature Sensitivity of the ...

EPA Pesticide Factsheets

The Total Maximum Daily Load (TMDL) program, established by the Clean Water Act, is used to establish limits on loading of pollutants from point and nonpoint sources necessary to achieve water quality standards. One important use of a temperature TMDL is to allocate thermal loads to achieve water temperature criteria established for the protection of cold water fisheries. The pollutant in this case is thermal load and allocations to reduce the load often involve restoration of stream shading, which reduces the solar input. While many temperature TMDLs have been established, the supporting analyses have generally assumed a stationary climate under which historical data on flow and air temperature can serve as an adequate guide to future conditions. Projected changes in climate over the 21st century contradict this assumption. Air temperature is expected to increase in most parts of the US, accompanied in many areas by seasonal shifts in the timing and amount of precipitation, which in turn will alter stream flow. This study evaluates the implications of climate change for the water temperature TMDL developed for the South Fork Nooksack River in northwest Washington by the Department of Ecology, where multiple water body segments exceed temperature criteria established for the protection of cold water salmonid populations (Ecology, 2016). The purpose of this report is to provide a “companion technical methods manual” as documentation for the draft SFNR tempera

Dramatic decreases in runoff and sediment load in the Huangfuchuan Basin of the Middle Yellow River, China: historical records and future projections

NASA Astrophysics Data System (ADS)

LI, E.; Li, D.; Wang, Y.; Fu, X.

2017-12-01

The Yellow River is well known for its high sediment load and serious water shortage. The long-term averaged sediment load is about 1.6´103 million tons per year, resulting in aggrading and perched lower reaches. In recent years, however, dramatic decreases in runoff and sediment load have been observed. The annual sediment load has been less than 150 million tons in the last ten years. Extrapolation of this trend into the future would motivate substantial change in the management strategies of the Lower Yellow River. To understand the possible trend and its coevolving drivers, we performed a case study of the Huangfuchuang River, which is a tributary to the Middle Yellow River, with a drainage area of 3246 km2 and an annual precipitation of 365 mm. Statistical analysis of historical data from 1960s to 2015 showed a significantly decreasing trend in runoff and sediment load since 1984. As potential drivers, the precipitation does not show an obvious change in annual amount, while the vegetation cover and the number of check dams have been increased gradually as a result of the national Grain for Green project. A simulation with the Soil and Water Assessment Tool (SWAT) reproduced the historical evolution processes, and showed that human activities dominated the reduction in runoff and sediment load, with a contribution of around 80%. We then projected the runoff and sediment load for the next 50 years (2016-2066), considering typical scenarios of climate change and accounting for vegetation cover development subject to climate conditions and storage capacity loss of check dams due to sediment deposition. The differences between the projected trend and the historical record were analyzed, so as to highlight the coevolving processes of climate, vegetation, and check dam retention on a time scale of decades. Keywords: Huangfuchuan River Basin, sediment load, vegetation cover, check dams, annual precipitation, SWAT.

Assessing natural and anthropogenic influences on water discharge and sediment load in the Yangtze River, China.

PubMed

Zhao, Yifei; Zou, Xinqing; Liu, Qing; Yao, Yulong; Li, Yali; Wu, Xiaowei; Wang, Chenglong; Yu, Wenwen; Wang, Teng

2017-12-31

The water discharge and sediment load of rivers are changing substantially under the impacts of climate change and human activities, becoming a hot issue in hydro-environmental research. In this study, the water discharge and sediment load in the mainstream and seven tributaries of the Yangtze River were investigated by using long-term hydro-meteorological data from 1953 to 2013. The non-parametric Mann-Kendall test and double mass curve (DMC) were used to detect trends and abrupt change-points in water discharge and sediment load and to quantify the effects of climate change and human activities on water discharge and sediment load. The results are as follows: (1) the water discharge showed a non-significant decreasing trend at most stations except Hukou station. Among these, water discharge at Dongting Lake and the Min River basin shows a significant decreasing trend with average rates of -13.93×10 8 m 3 /year and -1.8×10 8 m 3 /year (P<0.05), respectively. However, the sediment load exhibited a significant decreasing trend in all tributaries of the Yangtze River. (2) No significant abrupt change-points were detected in the time series of water discharge for all hydrological stations. In contrast, significant abrupt change-points were detected in sediment load, most of these changes appeared in the late 1980s. (3) The water discharge was mainly influenced by precipitation in the Yangtze River basin, whereas sediment load was mainly affected by climate change and human activities; the relative contribution ratios of human activities were above 70% for the Yangtze River. (4) The decrease of sediment load has directly impacted the lower Yangtze River and the delta region. These results will provide a reference for better resource management in the Yangtze River Basin. Copyright © 2017 Elsevier B.V. All rights reserved.

Geoengineering as an optimization problem

NASA Astrophysics Data System (ADS)

Ban-Weiss, George A.; Caldeira, Ken

2010-07-01

There is increasing evidence that Earth's climate is currently warming, primarily due to emissions of greenhouse gases from human activities, and Earth has been projected to continue warming throughout this century. Scientists have begun to investigate the potential for geoengineering options for reducing surface temperatures and whether such options could possibly contribute to environmental risk reduction. One proposed method involves deliberately increasing aerosol loading in the stratosphere to scatter additional sunlight to space. Previous modeling studies have attempted to predict the climate consequences of hypothetical aerosol additions to the stratosphere. These studies have shown that this method could potentially reduce surface temperatures, but could not recreate a low-CO2 climate in a high-CO2 world. In this study, we attempt to determine the latitudinal distribution of stratospheric aerosols that would most closely achieve a low-CO2 climate despite high CO2 levels. Using the NCAR CAM3.1 general circulation model, we find that having a stratospheric aerosol loading in polar regions higher than that in tropical regions leads to a temperature distribution that is more similar to the low-CO2 climate than that yielded by a globally uniform loading. However, such polar weighting of stratospheric sulfate tends to degrade the degree to which the hydrological cycle is restored, and thus does not markedly contribute to improved recovery of a low-CO2 climate. In the model, the optimal latitudinally varying aerosol distributions diminished the rms zonal mean land temperature change from a doubling of CO2 by 94% and the rms zonal mean land precipitation minus evaporation change by 74%. It is important to note that this idealized study represents a first attempt at optimizing the engineering of climate using a general circulation model; uncertainties are high and not all processes that are important in reality are modeled.

Are watershed and lacustrine controls on planktonic N2 fixation hierarchically structured?

PubMed

Scott, J Thad; Doyle, Robert D; Prochnow, Shane J; White, Joseph D

2008-04-01

N2 fixation can be an important source of N to limnetic ecosystems and can influence the structure of phytoplankton communities. However, watershed-scale conditions that favor N2 fixation in lakes and reservoirs have not been well studied. We measured N2 fixation and lacustrine variables monthly over a 19-month period in Waco Reservoir, Texas, USA, and linked these data with nutrient-loading estimates from a physically based watershed model. Readily available topographic, soil, land cover, effluent discharge, and climate data were used in the Soil and Water Assessment Tool (SWAT) to derive watershed nutrient-loading estimates. Categorical and regression tree (CART) analysis revealed that lacustrine and watershed correlates of N2 fixation were hierarchically structured. Lacustrine conditions showed greater predictive capability temporally. For instance, low NO3(-) concentration (<25 microg N/L) and high water temperatures (>27 degrees C) in the reservoir were correlated with the initiation of N2 fixation seasonally. When lacustrine conditions were favorable for N2 fixation, watershed conditions appeared to influence spatial patterns of N2 fixation within the reservoir. For example, spatially explicit patterns of N2 fixation were correlated with the ratio of N:P in nutrient loadings and the N loading rate, which were driven by anthropogenic activity in the watershed and periods of low stream flow, respectively. Although N2 fixation contributed <5% of the annual N load to the reservoir, 37% of the N load was derived from atmospheric N2 fixation during summertime when stream flow in the watershed was low. This study provides evidence that watershed anthropogenic activity can exert control on planktonic N2 fixation, but that temporality is controlled by lacustrine conditions. Furthermore, this study also supports suggestions that reduced inflows may increase the propensity of N2-fixing cyanobacterial blooms in receiving waters of anthropogenically modified landscapes.

Urban Runoff and Nutrients Loading Control from Sustainable BMPs (Invited)

NASA Astrophysics Data System (ADS)

Xiao, Q.

2009-12-01

Climate change alters hydrodynamic and nutrient dynamic in both large and small geographic scales. These changes in our freshwater system directly affect drinking water, food production, business, and all aspects of our life. Along with climate change is increasing urbanization which alters natural landscape. Urban runoff has been identified as one of many potential drivers of the decline of pelagic fishes in san Francisco Bay-Delta region. Recent found of Pyrethroids in American River has increased scientists, public, and policy makers’ concern about our fresh water system. Increasing our understanding about the fundamental hydrodynamic, nutrient dynamics, and the transport mechanics of runoff and nutrients are important for future water resource and ecosystem management. Urbanization has resulted in significantly increasing the amount of impervious land cover. Most impervious land covers are hydrophobic that alters surface runoff because of the effects on surface retention storage, rainfall interception, and infiltration. Large volumes of excess storm runoff from urbanized areas cause flooding, water pollution, groundwater recharge deficits, destroyed habitat, beach closures, and toxicity to aquatic organisms. Parking lot alone accounts for more than 11% of these impervious surfaces. Contrast to impervious parking lot, turfgrass can accouter for 12% of urban land in California. Irrigated urban landscapes create considerable benefits to our daily living. However, the use of fertilizers and pesticides has caused environmental problems. Preventing fertilizers and pesticides from entering storm drains is an important goal for both landscape and storm runoff managers. Studies of urban runoff have found that the most fertilizers and pesticides are from dry weather runoff which conveys pollutants to sidewalks, streets, and storm drains. Controlling surface runoff is critical to preventing these pollutants from entering storm drains and water bodies. Large scale construction of runoff retention basins and treatment facilities to meet TMDL (Total Maximum Daily Load) regulations are not cost-effective or practical. An alternative approach is to control runoff and nutrients on-site through installation of decentralized BMPs that detain and infiltrate runoff before it reaches storm drains. Recent developed green-infrastructure which integrating engineered soil and trees to reduce runoff and nutrients loading is a self-sustained best management practice (BMP). This BMP has been testing and used in urban runoff control. In Davis, CA this type of BMPs were installed in a parking lot and a residential property to evaluate the system’s effectiveness on reducing storm runoff and pollutant loading from the parking lot and irrigated landscape. Storm runoff and pollutant loading were measured and monitored during February 2007 thru May 2009 from the parking lot. The BMP reduced surface runoff and nutrients by 88.8% and 95.3%, respectively. In the residential irrigated landscape, the dry-weather runoff was monitored during 2007 irrigation season, the BMP captured almost all dry weather runoff. The performance of these BMPs demonstrated their potential use for reducing runoff and nutrients loading. Control urban runoff from these 23% landscape (i.e., parking lot and irrigated turf grass) could largely alter the runoff and nutrients transport and their dynamic in our water system.

Human deforestation outweighs future climate change impacts of sedimentation on coral reefs

PubMed Central

Maina, Joseph; de Moel, Hans; Zinke, Jens; Madin, Joshua; McClanahan, Tim; Vermaat, Jan E.

2013-01-01

Near-shore coral reef systems are experiencing increased sediment supply due to conversion of forests to other land uses. Counteracting increased sediment loads requires an understanding of the relationship between forest cover and sediment supply, and how this relationship might change in the future. Here we study this relationship by simulating river flow and sediment supply in four watersheds that are adjacent to Madagascar’s major coral reef ecosystems for a range of future climate change projections and land-use change scenarios. We show that by 2090, all four watersheds are predicted to experience temperature increases and/or precipitation declines that, when combined, result in decreases in river flow and sediment load. However, these climate change-driven declines are outweighed by the impact of deforestation. Consequently, our analyses suggest that regional land-use management is more important than mediating climate change for influencing sedimentation of Malagasy coral reefs. PMID:23736941

Human deforestation outweighs future climate change impacts of sedimentation on coral reefs.

PubMed

Maina, Joseph; de Moel, Hans; Zinke, Jens; Madin, Joshua; McClanahan, Tim; Vermaat, Jan E

2013-01-01

Near-shore coral reef systems are experiencing increased sediment supply due to conversion of forests to other land uses. Counteracting increased sediment loads requires an understanding of the relationship between forest cover and sediment supply, and how this relationship might change in the future. Here we study this relationship by simulating river flow and sediment supply in four watersheds that are adjacent to Madagascar's major coral reef ecosystems for a range of future climate change projections and land-use change scenarios. We show that by 2090, all four watersheds are predicted to experience temperature increases and/or precipitation declines that, when combined, result in decreases in river flow and sediment load. However, these climate change-driven declines are outweighed by the impact of deforestation. Consequently, our analyses suggest that regional land-use management is more important than mediating climate change for influencing sedimentation of Malagasy coral reefs.

Human exposure to environmental health concern by types of urban environment: The case of Tel Aviv.

PubMed

Schnell, Izhak; Potchter, Oded; Yaakov, Yaron; Epstein, Yoram

2016-01-01

This study classifies urban environments into types characterized by different exposure to environmental risk factors measured by general sense of discomfort and Heart Rate Variability (HRV). We hypothesize that a set of environmental factors (micro-climatic, CO, noise and individual heart rate) that were measured simultaneously in random locations can provide a better understanding of the distribution of human exposure to environmental loads throughout the urban space than results calculated based on measurements from close fixed stations. We measured micro-climatic and thermal load, CO and noise, individual Heart Rate, Subjective Social Load and Sense of Discomfort (SD) were tested by questionnaire survey. The results demonstrate significant differences in exposure to environmental factors among 8 types of urban environments. It appears that noise and social load are the more significant environmental factors to enhance health risks and general sense of discomfort. Copyright © 2015 Elsevier Ltd. All rights reserved.

Advanced Intelligent System Application to Load Forecasting and Control for Hybrid Electric Bus

NASA Technical Reports Server (NTRS)

Momoh, James; Chattopadhyay, Deb; Elfayoumy, Mahmoud

1996-01-01

The primary motivation for this research emanates from providing a decision support system to the electric bus operators in the municipal and urban localities which will guide the operators to maintain an optimal compromise among the noise level, pollution level, fuel usage etc. This study is backed up by our previous studies on study of battery characteristics, permanent magnet DC motor studies and electric traction motor size studies completed in the first year. The operator of the Hybrid Electric Car must determine optimal power management schedule to meet a given load demand for different weather and road conditions. The decision support system for the bus operator comprises three sub-tasks viz. forecast of the electrical load for the route to be traversed divided into specified time periods (few minutes); deriving an optimal 'plan' or 'preschedule' based on the load forecast for the entire time-horizon (i.e., for all time periods) ahead of time; and finally employing corrective control action to monitor and modify the optimal plan in real-time. A fully connected artificial neural network (ANN) model is developed for forecasting the kW requirement for hybrid electric bus based on inputs like climatic conditions, passenger load, road inclination, etc. The ANN model is trained using back-propagation algorithm employing improved optimization techniques like projected Lagrangian technique. The pre-scheduler is based on a Goal-Programming (GP) optimization model with noise, pollution and fuel usage as the three objectives. GP has the capability of analyzing the trade-off among the conflicting objectives and arriving at the optimal activity levels, e.g., throttle settings. The corrective control action or the third sub-task is formulated as an optimal control model with inputs from the real-time data base as well as the GP model to minimize the error (or deviation) from the optimal plan. These three activities linked with the ANN forecaster proving the output to the GP model which in turn produces the pre-schedule of the optimal control model. Some preliminary results based on a hypothetical test case will be presented for the load forecasting module. The computer codes for the three modules will be made available fe adoption by bus operating agencies. Sample results will be provided using these models. The software will be a useful tool for supporting the control systems for the Electric Bus project of NASA.

The role of baseflow in dissolved solids delivery to streams in the Upper Colorado River Basin

NASA Astrophysics Data System (ADS)

Rumsey, C.; Miller, M. P.; Schwarz, G. E.; Susong, D.

2017-12-01

Salinity has a major effect on water users in the Colorado River Basin, estimated to cause almost $300 million per year in economic damages. The Colorado River Basin Salinity Control Program implements and manages projects to reduce salinity (dissolved solids) loads, investing millions of dollars per year in irrigation upgrades, canal projects, and other mitigation strategies. To inform and improve mitigation efforts, there is a need to better understand sources of salinity to streams and how salinity has changed over time. This study explores salinity in baseflow, or groundwater discharge to streams, to assess whether groundwater is a significant contributor of dissolved solids to streams in the Upper Colorado River Basin (UCRB). Chemical hydrograph separation was used to estimate long-term mean annual baseflow discharge and baseflow dissolved solids loads at stream gages (n=69) across the UCRB. On average, it is estimated that 89% of dissolved solids loads originate from the baseflow fraction of streamflow. Additionally, a statistical trend analysis using weighted regressions on time, discharge, and season was used to evaluate changes in baseflow dissolved solids loads in streams with data from 1987 to 2011 (n=29). About two-thirds (62%) of these streams showed statistically significant decreasing trends in baseflow dissolved solids loads. At the two most downstream sites, Green River at Green River, UT and Colorado River at Cisco, UT, baseflow dissolved solids loads decreased by a combined 780,000 metric tons, which is approximately 65% of the estimated basin-scale decrease in total dissolved solids loads in the UCRB attributed to salinity control efforts. Results indicate that groundwater discharged to streams, and therefore subsurface transport processes, play a large role in delivering dissolved solids to streams in the UCRB. Decreasing trends in baseflow dissolved solids loads suggest that salinity mitigation projects, changes in land use, and/or climate are decreasing salinity in groundwater transported to streams.

Modeling transport of nutrients & sediment loads into Lake Tahoe under climate change

USGS Publications Warehouse

Riverson, John; Coats, Robert; Costa-Cabral, Mariza; Dettinger, Mike; Reuter, John; Sahoo, Goloka; Schladow, Geoffrey

2013-01-01

The outputs from two General Circulation Models (GCMs) with two emissions scenarios were downscaled and bias-corrected to develop regional climate change projections for the Tahoe Basin. For one model—the Geophysical Fluid Dynamics Laboratory or GFDL model—the daily model results were used to drive a distributed hydrologic model. The watershed model used an energy balance approach for computing evapotranspiration and snowpack dynamics so that the processes remain a function of the climate change projections. For this study, all other aspects of the model (i.e. land use distribution, routing configuration, and parameterization) were held constant to isolate impacts of climate change projections. The results indicate that (1) precipitation falling as rain rather than snow will increase, starting at the current mean snowline, and moving towards higher elevations over time; (2) annual accumulated snowpack will be reduced; (3) snowpack accumulation will start later; and (4) snowmelt will start earlier in the year. Certain changes were masked (or counter-balanced) when summarized as basin-wide averages; however, spatial evaluation added notable resolution. While rainfall runoff increased at higher elevations, a drop in total precipitation volume decreased runoff and fine sediment load from the lower elevation meadow areas and also decreased baseflow and nitrogen loads basin-wide. This finding also highlights the important role that the meadow areas could play as high-flow buffers under climatic change. Because the watershed model accounts for elevation change and variable meteorological patterns, it provided a robust platform for evaluating the impacts of projected climate change on hydrology and water quality.

Declining sediment loads from Redwood Creek and the Klamath River, north coastal California

Treesearch

Randy D. Klein; Jeffrey K. Anderson

2012-01-01

River basin sediment loads are affected by several factors, with flood magnitude and watershed erosional stability playing dominant and dynamic roles. Long-term average sediment loads for northern California river basins have been computed by several researchers by several methods. However, characterizing the dynamic nature of climate and watershed stability requires...

Land Use and Climate Variability Amplify Contaminant Pulses

EPA Science Inventory

Converting land to human-dominated uses has increased contaminant loads in streams and rivers and vastly transformed hydrological cycles (Vitousek et al. 1997). More recently, climate change has further altered hydrologic cycles and variability of precipitation (IPCC 2007). Toge...

Temporal and spatial climatic controls on Holocene fire-related erosion and sedimentation, Jemez Mountains, New Mexico

NASA Astrophysics Data System (ADS)

Fitch, Erin P.; Meyer, Grant A.

2016-01-01

In the Jemez Mountains, tree-ring data indicate that low-severity fires characterized the 400 yr before Euro-American settlement, and that subsequent fire suppression promoted denser forests, recent severe fires, and erosion. Over longer timescales, climate change may alter fire regimes; thus, we used fire-related alluvial deposits to assess the timing of moderate- to high-severity fires, their geomorphic impact, and relation to climate over the last 4000 yr. Fire-related sedimentation does not clearly follow millennial-scale climatic changes, but probability peaks commonly correspond with severe drought, e.g., within the interval 1700-1400 cal yr BP, and ca. 650 and ca. 410 cal yr BP. The latter episodes were preceded by prolonged wet intervals that could promote dense stands. Estimated recurrence intervals for fire-related sedimentation are 250-400 yr. Climatic differences with aspect influenced Holocene post-fire response: fire-related deposits constitute 77% of fan sediments from north-facing basins but only 39% of deposits from drier southerly aspects. With sparser vegetation and exposed bedrock, south aspects can generate runoff and sediment when unburned, whereas soil-mantled north aspects produce minor sediment unless severely burned. Recent channel incision appears unprecedented over the last 2300 yr, suggesting that fuel loading and extreme drought produced an anomalously severe burn in 2002.

6. Detail view north of typical window and loading door ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

6. Detail view north of typical window and loading door at east end of south elevation. - Natick Research & Development Laboratories, Climatic Chambers Building, U.S. Army Natick Research, Development & Engineering Center (NRDEC), Natick, Middlesex County, MA

Identification of key climatic factors regulating the transport of pesticides in leaching and to tile drains.

PubMed

Nolan, Bernard T; Dubus, Igor G; Surdyk, Nicolas; Fowler, Hayley J; Burton, Aidan; Hollis, John M; Reichenberger, Stefan; Jarvis, Nicholas J

2008-09-01

Key climatic factors influencing the transport of pesticides to drains and to depth were identified. Climatic characteristics such as the timing of rainfall in relation to pesticide application may be more critical than average annual temperature and rainfall. The fate of three pesticides was simulated in nine contrasting soil types for two seasons, five application dates and six synthetic weather data series using the MACRO model, and predicted cumulative pesticide loads were analysed using statistical methods. Classification trees and Pearson correlations indicated that simulated losses in excess of 75th percentile values (0.046 mg m(-2) for leaching, 0.042 mg m(-2) for drainage) generally occurred with large rainfall events following autumn application on clay soils, for both leaching and drainage scenarios. The amount and timing of winter rainfall were important factors, whatever the application period, and these interacted strongly with soil texture and pesticide mobility and persistence. Winter rainfall primarily influenced losses of less mobile and more persistent compounds, while short-term rainfall and temperature controlled leaching of the more mobile pesticides. Numerous climatic characteristics influenced pesticide loss, including the amount of precipitation as well as the timing of rainfall and extreme events in relation to application date. Information regarding the relative influence of the climatic characteristics evaluated here can support the development of a climatic zonation for European-scale risk assessment for pesticide fate.

Comparative analyses of hydrological responses of two adjacent watersheds to climate variability and change using the SWAT model

USGS Publications Warehouse

Lee, Sangchul; Yeo, In-Young; Sadeghi, Ali M.; McCarty, Gregory W.; Hively, Wells; Lang, Megan W.; Sharifi, Amir

2018-01-01

Water quality problems in the Chesapeake Bay Watershed (CBW) are expected to be exacerbated by climate variability and change. However, climate impacts on agricultural lands and resultant nutrient loads into surface water resources are largely unknown. This study evaluated the impacts of climate variability and change on two adjacent watersheds in the Coastal Plain of the CBW, using the Soil and Water Assessment Tool (SWAT) model. We prepared six climate sensitivity scenarios to assess the individual impacts of variations in CO2concentration (590 and 850 ppm), precipitation increase (11 and 21 %), and temperature increase (2.9 and 5.0 °C), based on regional general circulation model (GCM) projections. Further, we considered the ensemble of five GCM projections (2085–2098) under the Representative Concentration Pathway (RCP) 8.5 scenario to evaluate simultaneous changes in CO2, precipitation, and temperature. Using SWAT model simulations from 2001 to 2014 as a baseline scenario, predicted hydrologic outputs (water and nitrate budgets) and crop growth were analyzed. Compared to the baseline scenario, a precipitation increase of 21 % and elevated CO2 concentration of 850 ppm significantly increased streamflow and nitrate loads by 50 and 52 %, respectively, while a temperature increase of 5.0 °C reduced streamflow and nitrate loads by 12 and 13 %, respectively. Crop biomass increased with elevated CO2 concentrations due to enhanced radiation- and water-use efficiency, while it decreased with precipitation and temperature increases. Over the GCM ensemble mean, annual streamflow and nitrate loads showed an increase of  ∼  70 % relative to the baseline scenario, due to elevated CO2 concentrations and precipitation increase. Different hydrological responses to climate change were observed from the two watersheds, due to contrasting land use and soil characteristics. The watershed with a larger percent of croplands demonstrated a greater increased rate of 5.2 kg N ha−1 in nitrate yield relative to the watershed with a lower percent of croplands as a result of increased export of nitrate derived from fertilizer. The watershed dominated by poorly drained soils showed increased nitrate removal due do enhanced denitrification compared to the watershed dominated by well-drained soils. Our findings suggest that increased implementation of conservation practices would be necessary for this region to mitigate increased nitrate loads associated with predicted changes in future climate.

Groundwater nitrate concentration evolution under climate change and agricultural adaptation scenarios: Prince Edward Island, Canada

NASA Astrophysics Data System (ADS)

Paradis, Daniel; Vigneault, Harold; Lefebvre, René; Savard, Martine M.; Ballard, Jean-Marc; Qian, Budong

2016-03-01

Nitrate (N-NO3) concentration in groundwater, the sole source of potable water in Prince Edward Island (PEI, Canada), currently exceeds the 10 mg L-1 (N-NO3) health threshold for drinking water in 6 % of domestic wells. Increasing climatic and socio-economic pressures on PEI agriculture may further deteriorate groundwater quality. This study assesses how groundwater nitrate concentration could evolve due to the forecasted climate change and its related potential changes in agricultural practices. For this purpose, a tridimensional numerical groundwater flow and mass transport model was developed for the aquifer system of the entire Island (5660 km2). A number of different groundwater flow and mass transport simulations were made to evaluate the potential impact of the projected climate change and agricultural adaptation. According to the simulations for year 2050, N-NO3 concentration would increase due to two main causes: (1) the progressive attainment of steady-state conditions related to present-day nitrogen loadings, and (2) the increase in nitrogen loadings due to changes in agricultural practices provoked by future climatic conditions. The combined effects of equilibration with loadings, climate and agricultural adaptation would lead to a 25 to 32 % increase in N-NO3 concentration over the Island aquifer system. The change in groundwater recharge regime induced by climate change (with current agricultural practices) would only contribute 0 to 6 % of that increase for the various climate scenarios. Moreover, simulated trends in groundwater N-NO3 concentration suggest that an increased number of domestic wells (more than doubling) would exceed the nitrate drinking water criteria. This study underlines the need to develop and apply better agricultural management practices to ensure sustainability of long-term groundwater resources. The simulations also show that observable benefits from positive changes in agricultural practices would be delayed in time due to the slow dynamics of nitrate transport within the aquifer system.

Groundwater nitrate concentration evolution under climate change and agricultural adaptation scenarios: Prince Edward Island, Canada

NASA Astrophysics Data System (ADS)

Paradis, D.; Vigneault, H.; Lefebvre, R.; Savard, M. M.; Ballard, J.-M.; Qian, B.

2015-08-01

Nitrate (N-NO3) concentration in groundwater, the sole source of potable water in Prince Edward Island (PEI, Canada), currently exceeds the 10 mg L-1 (N-NO3) health threshold for drinking water in 6 % of domestic wells. Increasing climatic and socio-economic pressures on PEI agriculture may further deteriorate groundwater quality. This study assesses how groundwater nitrate concentrations could evolve due to the forecasted climate change and its related potential changes in agricultural practices. For this purpose, a tridimensional numerical groundwater flow and mass transport model was developed for the aquifer system of the entire Island (5660 km2). A number of different groundwater flow and mass transport simulations were made to evaluate the potential impact of the projected climate change and agricultural adaptation. According to the simulations for year 2050, N-NO3 concentration would increase due to two main causes: (1) the progressive attainment of steady-state conditions related to present-day nitrogen loadings, and (2) the increase in nitrogen loadings due to changes in agricultural practices provoked by future climatic conditions. The combined effects of equilibration with loadings, climate and agricultural adaptation would lead to a 25 to 32 % increase in N-NO3 concentration over the Island aquifer system. Climate change alone (practices maintained at their current level) would contribute only 0 to 6 % to that increase according to the various climate scenarios. Moreover, simulated trends in groundwater N-NO3 concentration suggest that an increased number of domestic wells (more than doubling) would exceed the nitrate drinking water criteria. This study underlines the need to develop and apply better agricultural management practices to ensure sustainability of long-term groundwater resources. The simulations also show that observable benefits from positive changes in agricultural practices would be delayed in time due to the slow dynamics of nitrate transport within the aquifer system.

Assessing climate change impacts on winter cover crop nitrate uptake efficiency on the coastal plain of the Chesapeake Bay watershed using the SWAT model

USDA-ARS?s Scientific Manuscript database

Climate change is expected to exacerbate water quality degradation in the Chesapeake Bay watershed (CBW). Winter cover crops (WCCs) have been widely implemented in this region owing to their high effectiveness at reducing nitrate loads. However, little is known about climate change impacts on the ef...

Response in the trophic state of stratified lakes to changes in hydrology and water level: potential effects of climate change

USGS Publications Warehouse

Robertson, Dale M.; Rose, William J.

2011-01-01

To determine how climate-induced changes in hydrology and water level may affect the trophic state (productivity) of stratified lakes, two relatively pristine dimictic temperate lakes in Wisconsin, USA, were examined. Both are closed-basin lakes that experience changes in water level and degradation in water quality during periods of high water. One, a seepage lake with no inlets or outlets, has a small drainage basin and hydrology dominated by precipitation and groundwater exchange causing small changes in water and phosphorus (P) loading, which resulted in small changes in water level, P concentrations, and productivity. The other, a terminal lake with inlets but no outlets, has a large drainage basin and hydrology dominated by runoff causing large changes in water and P loading, which resulted in large changes in water level, P concentrations, and productivity. Eutrophication models accurately predicted the effects of changes in hydrology, P loading, and water level on their trophic state. If climate changes, larger changes in hydrology and water levels than previously observed could occur. If this causes increased water and P loading, stratified (dimictic and monomictic) lakes are expected to experience higher water levels and become more eutrophic, especially those with large developed drainage basins.

Modelling the combined impacts of climate change and direct anthropogenic drivers on the ecosystem of the northwest European continental shelf

NASA Astrophysics Data System (ADS)

Wakelin, Sarah L.; Artioli, Yuri; Butenschön, Momme; Allen, J. Icarus; Holt, Jason T.

2015-12-01

The potential response of the marine ecosystem of the northwest European continental shelf to climate change under a medium emissions scenario (SRES A1B) is investigated using the coupled hydrodynamics-ecosystem model POLCOMS-ERSEM. Changes in the near future (2030-2040) and the far future (2082-2099) are compared to the recent past (1983-2000). The sensitivity of the ecosystem to potential changes in multiple anthropogenic drivers (river nutrient loads and benthic trawling) in the near future is compared to the impact of changes in climate. With the exception of the biomass of benthic organisms, the influence of the anthropogenic drivers only exceeds the impact of climate change in coastal regions. Increasing river nitrogen loads has a limited impact on the ecosystem whilst reducing river nitrogen and phosphate concentrations affects net primary production (netPP) and phytoplankton and zooplankton biomass. Direct anthropogenic forcing is seen to mitigate/amplify the effects of climate change. Increasing river nitrogen has the potential to amplify the effects of climate change at the coast by increasing netPP. Reducing river nitrogen and phosphate mitigates the effects of climate change for netPP and the biomass of small phytoplankton and large zooplankton species but amplifies changes in the biomass of large phytoplankton and small zooplankton.

A conceptual framework: redifining forests soil's critical acid loads under a changing climate

Treesearch

Steven G. McNulty; Johnny L. Boggs

2010-01-01

Federal agencies of several nations have or are currently developing guidelines for critical forest soil acid loads. These guidelines are used to establish regulations designed to maintain atmospheric acid inputs below levels shown to damage forests and streams. Traditionally, when the critical soil acid load exceeds the amount of acid that the ecosystem can absorb, it...

The response of nitrous oxide emissions to different operating conditions in activated sludge wastewater treatment plants in Southeastern Brazil.

PubMed

Ribeiro, Renato P; Bueno, Rodrigo F; Piveli, Roque P; Kligerman, Débora C; de Mello, William Z; Oliveira, Jaime L M

2017-11-01

The continuous measurements of N 2 O emissions from the aeration tanks of three activated sludge wastewater treatment plants (WWTPs) operated with biological nitrogen removal (BNR) and non-BNR were performed during the different operating conditions of several parameters, such as aeration, dissolved oxygen (DO) profiling and organic shock loading (with landfill leachate). The nitrification process is the main driving force behind N 2 O emission peaks. There are indications that the variation of the air flow rate influenced N 2 O emissions; high N 2 O emissions denote over-aeration conditions or incomplete nitrification, with accumulation of NO 2 - concentrations. Thus, continuous measurements of N 2 O emissions can provide information on aeration adequacy and the efficiency of complete nitrification, with major focus on DO control, in order to reduce N 2 O emissions. An additional concern is the observed propensity of WWTPs in developing countries to receive landfill leachates in their wastewater systems. This practice could have adverse effects on climate change, since wastewater treatment during periods of organic shock loading emitted significantly higher amounts of N 2 O than without organic shock loading. In short, non-BNR WWTPs are subject to high N 2 O emissions, in contrast to BNR WWTP with controlled nitrification and denitrification processes.

Experiences in solar cooling systems

NASA Astrophysics Data System (ADS)

Ward, D. S.

The results of performance evaluations for nine solar cooling systems are presented, and reasons fow low or high net energy balances are discussed. Six of the nine systems are noted to have performed unfavorably compared to standard cooling systems due to thermal storage losses, excessive system electrical demands, inappropriate control strategies, poor system-to-load matching, and poor chiller performance. A reduction in heat losses in one residential unit increased the total system efficiency by 2.5%, while eliminating heat losses to the building interior increased the efficiency by 3.3%. The best system incorporated a lithium bromide absorption chiller and a Rankine cycle compression unit for a commercial application. Improvements in the cooling tower and fan configurations to increase the solar cooling system efficiency are indicated. Best performances are expected to occur in climates inducing high annual cooling loads.

The thermal environment of the human being on the global scale.

PubMed

Jendritzky, Gerd; Tinz, Birger

2009-11-11

The close relationship between human health, performance, well-being and the thermal environment is obvious. Nevertheless, most studies of climate and climate change impacts show amazing shortcomings in the assessment of the environment. Populations living in different climates have different susceptibilities, due to socio-economic reasons, and different customary behavioural adaptations. The global distribution of risks of hazardous thermal exposure has not been analysed before. To produce maps of the baseline and future bioclimate that allows a direct comparison of the differences in the vulnerability of populations to thermal stress across the world. The required climatological data fields are obtained from climate simulations with the global General Circulation Model ECHAM4 in T106-resolution. For the thermo-physiologically relevant assessment of these climate data a complete heat budget model of the human being, the 'Perceived Temperature' procedure has been applied which already comprises adaptation by clothing to a certain degree. Short-term physiological acclimatisation is considered via Health Related Assessment of the Thermal Environment. The global maps 1971-1980 (control run, assumed as baseline climate) show a pattern of thermal stress intensities as frequencies of heat. The heat load for people living in warm-humid climates is the highest. Climate change will lead to clear differences in health-related thermal stress between baseline climate and the future bioclimate 2041-2050 based on the 'business-as-usual' greenhouse gas scenario IS92a. The majority of the world's population will be faced with more frequent and more intense heat strain in spite of an assumed level of acclimatisation. Further adaptation measures are crucial in order to reduce the vulnerability of the populations. This bioclimatology analysis provides a tool for various questions in climate and climate change impact research. Considerations of regional or local scale require climate simulations with higher resolution. As adaptation is the key term in understanding the role of climate/climate change for human health, performance and well-being, further research in this field is crucial.

Parametric Analysis of Energy Consumption in Army Buildings by the Building Loads Analysis and System Thermodynamics (BLAST) Computer Program.

DTIC Science & Technology

1980-08-01

orientation, and HVAC systems have on three Army buildings in five different climatic regions. f Optimization of EnerV Usage in Military Facilities...The clinic’s environment is maintained by a multizone air-handling unit served by its own boiler and chiller . The building was modeled with 30... setpoints for the space temperature. This type of throttling range allows the heating system to control around a throttling range of 67 to 69oF (19 to 200

Enhancement of urban heat load through social inequalities on an example of a fictional city King's Landing.

PubMed

Žuvela-Aloise, M

2017-03-01

The numerical model MUKLIMO_3 is used to simulate the urban climate of an imaginary city as an illustrative example to demonstrate that the residential areas with deprived socio-economic conditions can exhibit an enhanced heat load at night, and thus more disadvantageous environmental conditions, compared with the areas of higher socio-economic status. The urban climate modelling simulations differentiate between orographic, natural landscape, building and social effects, where social differences are introduced by selection of location, building type and amount of vegetation. The model results show that the increase of heat load can be found in the areas inhabited by the poor population as a combined effect of natural and anthropogenic factors. The unfavourable location in the city and the building type, consisting of high density, low housing with high fraction of pavement and small amount of vegetation contribute to the formation of excessive heat load. This abstract example shows that the enhancement of urban heat load can be linked to the concept of a socially stratified city and is independent of the historical development of any specific city.

Enhancement of urban heat load through social inequalities on an example of a fictional city King's Landing

NASA Astrophysics Data System (ADS)

Žuvela-Aloise, M.

2017-03-01

The numerical model MUKLIMO_3 is used to simulate the urban climate of an imaginary city as an illustrative example to demonstrate that the residential areas with deprived socio-economic conditions can exhibit an enhanced heat load at night, and thus more disadvantageous environmental conditions, compared with the areas of higher socio-economic status. The urban climate modelling simulations differentiate between orographic, natural landscape, building and social effects, where social differences are introduced by selection of location, building type and amount of vegetation. The model results show that the increase of heat load can be found in the areas inhabited by the poor population as a combined effect of natural and anthropogenic factors. The unfavourable location in the city and the building type, consisting of high density, low housing with high fraction of pavement and small amount of vegetation contribute to the formation of excessive heat load. This abstract example shows that the enhancement of urban heat load can be linked to the concept of a socially stratified city and is independent of the historical development of any specific city.

Short-term load forecasting of power system

NASA Astrophysics Data System (ADS)

Xu, Xiaobin

2017-05-01

In order to ensure the scientific nature of optimization about power system, it is necessary to improve the load forecasting accuracy. Power system load forecasting is based on accurate statistical data and survey data, starting from the history and current situation of electricity consumption, with a scientific method to predict the future development trend of power load and change the law of science. Short-term load forecasting is the basis of power system operation and analysis, which is of great significance to unit combination, economic dispatch and safety check. Therefore, the load forecasting of the power system is explained in detail in this paper. First, we use the data from 2012 to 2014 to establish the partial least squares model to regression analysis the relationship between daily maximum load, daily minimum load, daily average load and each meteorological factor, and select the highest peak by observing the regression coefficient histogram Day maximum temperature, daily minimum temperature and daily average temperature as the meteorological factors to improve the accuracy of load forecasting indicators. Secondly, in the case of uncertain climate impact, we use the time series model to predict the load data for 2015, respectively, the 2009-2014 load data were sorted out, through the previous six years of the data to forecast the data for this time in 2015. The criterion for the accuracy of the prediction is the average of the standard deviations for the prediction results and average load for the previous six years. Finally, considering the climate effect, we use the BP neural network model to predict the data in 2015, and optimize the forecast results on the basis of the time series model.

The effects of climate change on instream nitrogen transport in the contiguous United States

NASA Astrophysics Data System (ADS)

Alam, M. J.; Goodall, J. L.

2011-12-01

Excessive nitrogen loading has caused significant environmental impacts such as eutrophication and hypoxia in waterbodies around the world. Nitrogen loading is largely dependent on nonpoint source pollution and nitrogen transport from nonpoint source pollution is greatly impacted by climate conditions. For example, increased precipitation leads to more runoff and a higher nitrogen yield. However, higher temperatures also impact nitrogen transport in that higher temperatures increase denitrification and therefore reduce nitrogen yield. The purpose of this research is to quantify potential changes in nitrogen yield for the contiguous United States under predicted climate change scenarios, specifically changes in precipitation and air temperature. The analysis was performed for high (A2) and low (B1) emission scenarios and for the year 2030, 2050 and 2090. We used 11 different IPCC (The Intergovernmental Panel on Climate Change) models predicted precipitation and temperature estimates to capture uncertainty. The SPARROW model was calibrated using historical nitrogen loading data and used to predict nitrogen yields for future climate conditions. We held nitrogen source data constant in order to isolate the impact of predicted precipitation and temperature changes for each model scenario. Preliminary results suggest an overall decrease in nitrogen yield if climate change impacts are considered in isolation. For the A2 scenario, the model results indicated an overall incremental nitrogen yield decrease of 2-17% by the year 2030, 4-26% by the year 2050, and 11-45% by the year 2090. The B1 emission scenario also indicated an incremental yield decrease, but at lesser amounts of 2-18%, 5-21% and 10-38% by the years 2030, 2050, and 2090, respectively. This decrease is mainly due to higher predicted temperatures that result in increased denitrification rates.

Impacts of Landuse Management and Climate Change on Landslides Susceptibility over the Olympic Peninsula of Washington State

NASA Astrophysics Data System (ADS)

Barik, M. G.; Adam, J. C.

2009-12-01

The commercial forests on the western side of the Olympic Mountains in Washington State are a region of steep slopes and high annual rainfall (2500-6000 mm/year) and are therefore highly susceptible to landslides. Potential climatic change (more intense and frequent winter storms) may exacerbate landslide susceptibility unless forest management practices are changed. As this area is a critical habitat for numerous organisms, including salmon, this may result in potentially severe consequences to riparian habitat due to increased sediment loads. Therefore, there is a need to investigate potential forest management plans to promote the economic viability of timber extraction while protecting the natural habitat, particularly in riparian areas. The objective of this study is to predict the long term effects of forest management decisions under projected climate change on slope stability. We applied the physically-based Distributed Hydrology Soil Vegetation Model (DHSVM) with its sediment module to simulate mass wasting and sediment delivery under different vegetation and climate scenarios. Sub-basins were selected and classified according to elevation, slope, land cover and soil type. Various land management practices (such as clear-cutting in riparian areas, logging under short rotations, varying amount of timbers left intact in riparian areas) were applied to each of the selected sub-basins. DHSVM was used to simulate landslide volume, frequency, and sediment loads for each of the land cover applications under various future climate scenarios. We comment on the suitability of various harvesting techniques for different parts of the forest to minimize landslide-induced sediment loading to streams in an altered climate. This approach can be developed as a decision making tool that can be used by forest managers to make long-term planning decisions.

Predicting Impacts of Increased CO2 and Climate Change on the Water Cycle and Water Quality in the Semiarid James River Basin of the Midwestern USA

USGS Publications Warehouse

Wu, Yiping; Liu, Shu-Guang; Gallant, Alisa L.

2012-01-01

Emissions of greenhouse gases and aerosols from human activities continue to alter the climate and likely will have significant impacts on the terrestrial hydrological cycle and water quality, especially in arid and semiarid regions. We applied an improved Soil and Water Assessment Tool (SWAT) to evaluate impacts of increased atmospheric CO2 concentration and potential climate change on the water cycle and nitrogen loads in the semiarid James River Basin (JRB) in the Midwestern United States. We assessed responses of water yield, soil water content, groundwater recharge, and nitrate nitrogen (NO3–N) load under hypothetical climate-sensitivity scenarios in terms of CO2, precipitation, and air temperature. We extended our predictions of the dynamics of these hydrological variables into the mid-21st century with downscaled climate projections integrated across output from six General Circulation Models. Our simulation results compared against the baseline period 1980 to 2009 suggest the JRB hydrological system is highly responsive to rising levels of CO2 concentration and potential climate change. Under our scenarios, substantial decrease in precipitation and increase in air temperature by the mid-21st century could result in significant reduction in water yield, soil water content, and groundwater recharge. Our model also estimated decreased NO3–N load to streams, which could be beneficial, but a concomitant increase in NO3–N concentration due to a decrease in streamflow likely would degrade stream water and threaten aquatic ecosystems. These results highlight possible risks of drought, water supply shortage, and water quality degradation in this basin.

Optimal implementation of green infrastructure practices to minimize influences of land use change and climate change on hydrology and water quality: Case study in Spy Run Creek watershed, Indiana.

PubMed

Liu, Yaoze; Engel, Bernard A; Collingsworth, Paris D; Pijanowski, Bryan C

2017-12-01

Nutrient loading from the Maumee River watershed is a significant reason for the harmful algal blooms (HABs) problem in Lake Erie. The nutrient loading from urban areas needs to be reduced with the installation of green infrastructure (GI) practices. The Long-Term Hydrologic Impact Assessment-Low Impact Development 2.1 (L-THIA-LID 2.1) model was used to explore the influences of land use (LU) and climate change on water quantity and quality in Spy Run Creek watershed (SRCW) (part of Maumee River watershed), decide whether and where excess phosphorus loading existed, identify critical areas to understand where the greatest amount of runoff/pollutants originated, and optimally implement GI practices to obtain maximum environmental benefits with the lowest costs. Both LU/climate changes increased runoff/pollutants generated from the watershed. Areas with the highest runoff/pollutant amount per area, or critical areas, differed for various environmental concerns, land uses (LUs), and climates. Compared to optimization considering all areas, optimization conducted only in critical areas can provide similar cost-effective results with decreased computational time for low levels of runoff/pollutant reductions, but critical area optimization results were not as cost-effective for higher levels of runoff/pollutant reductions. Runoff/pollutants for 2011/2050 LUs/climates could be reduced to amounts of 2001 LU/climate by installation of GI practices with annual expenditures of $0.34 to $2.05 million. The optimization scenarios that were able to obtain the 2001 runoff level in 2011/2050, can also reduce all pollutants to 2001 levels in this watershed. Copyright © 2017 Elsevier B.V. All rights reserved.

Combined and synergistic effects of climate change and urbanization on water quality in the Wolf Bay watershed, southern Alabama.

PubMed

Wang, Ruoyu; Kalin, Latif

2018-02-01

This study investigated potential changes in flow, total suspended solid (TSS) and nutrient (nitrogen and phosphorous) loadings under future climate change, land use/cover (LULC) change and combined change scenarios in the Wolf Bay watershed, southern Alabama, USA. Four Global Circulation Models (GCMs) under three Special Report Emission Scenarios (SRES) of greenhouse gas were used to assess the future climate change (2016-2040). Three projected LULC maps (2030) were employed to reflect different extents of urbanization in future. The individual, combined and synergistic impacts of LULC and climate change on water quantity/quality were analyzed by the Soil and Water Assessment Tool (SWAT). Under the "climate change only" scenario, monthly distribution and projected variation of TSS are expected to follow a pattern similar to streamflow. Nutrients are influenced both by flow and management practices. The variation of Total Nitrogen (TN) and Total Phosphorous (TP) generally follow the flow trend as well. No evident difference in the N:P ratio was projected. Under the "LULC change only" scenario, TN was projected to decrease, mainly due to the shrinkage of croplands. TP will increase in fall and winter. The N:P ratio shows a strong decreasing potential. Under the "combined change" scenario, LULC and climate change effect were considered simultaneously. Results indicate that if future loadings are expected to increase/decrease under any individual scenario, then the combined change will intensify that trend. Conversely, if their effects are in opposite directions, an offsetting effect occurs. Science-based management practices are needed to reduce nutrient loadings to the Bay. Copyright © 2017. Published by Elsevier B.V.

Predicting impacts of increased CO₂ and climate change on the water cycle and water quality in the semiarid James River Basin of the Midwestern USA.

PubMed

Wu, Yiping; Liu, Shuguang; Gallant, Alisa L

2012-07-15

Emissions of greenhouse gases and aerosols from human activities continue to alter the climate and likely will have significant impacts on the terrestrial hydrological cycle and water quality, especially in arid and semiarid regions. We applied an improved Soil and Water Assessment Tool (SWAT) to evaluate impacts of increased atmospheric CO(2) concentration and potential climate change on the water cycle and nitrogen loads in the semiarid James River Basin (JRB) in the Midwestern United States. We assessed responses of water yield, soil water content, groundwater recharge, and nitrate nitrogen (NO(3)-N) load under hypothetical climate-sensitivity scenarios in terms of CO(2), precipitation, and air temperature. We extended our predictions of the dynamics of these hydrological variables into the mid-21st century with downscaled climate projections integrated across output from six General Circulation Models. Our simulation results compared against the baseline period 1980 to 2009 suggest the JRB hydrological system is highly responsive to rising levels of CO(2) concentration and potential climate change. Under our scenarios, substantial decrease in precipitation and increase in air temperature by the mid-21st century could result in significant reduction in water yield, soil water content, and groundwater recharge. Our model also estimated decreased NO(3)-N load to streams, which could be beneficial, but a concomitant increase in NO(3)-N concentration due to a decrease in streamflow likely would degrade stream water and threaten aquatic ecosystems. These results highlight possible risks of drought, water supply shortage, and water quality degradation in this basin. Published by Elsevier B.V.

Species interactions and response time to climate change: ice-cover and terrestrial run-off shaping Arctic char and brown trout competitive asymmetries

NASA Astrophysics Data System (ADS)

Finstad, A. G.; Palm Helland, I.; Jonsson, B.; Forseth, T.; Foldvik, A.; Hessen, D. O.; Hendrichsen, D. K.; Berg, O. K.; Ulvan, E.; Ugedal, O.

2011-12-01

There has been a growing recognition that single species responses to climate change often mainly are driven by interaction with other organisms and single species studies therefore not are sufficient to recognize and project ecological climate change impacts. Here, we study how performance, relative abundance and the distribution of two common Arctic and sub-Arctic freshwater fishes (brown trout and Arctic char) are driven by competitive interactions. The interactions are modified both by direct climatic effects on temperature and ice-cover, and indirectly through climate forcing of terrestrial vegetation pattern and associated carbon and nutrient run-off. We first use laboratory studies to show that Arctic char, which is the world's most northernmost distributed freshwater fish, outperform trout under low light levels and also have comparable higher growth efficiency. Corresponding to this, a combination of time series and time-for-space analyses show that ice-cover duration and carbon and nutrient load mediated by catchment vegetation properties strongly affected the outcome of the competition and likely drive the species distribution pattern through competitive exclusion. In brief, while shorter ice-cover period and decreased carbon load favored brown trout, increased ice-cover period and increased carbon load favored Arctic char. Length of ice-covered period and export of allochthonous material from catchments are major, but contrasting, climatic drivers of competitive interaction between these two freshwater lake top-predators. While projected climate change lead to decreased ice-cover, corresponding increase in forest and shrub cover amplify carbon and nutrient run-off. Although a likely outcome of future Arctic and sub-arctic climate scenarios are retractions of the Arctic char distribution area caused by competitive exclusion, the main drivers will act on different time scales. While ice-cover will change instantaneously with increasing temperature, changes in catchment vegetation, such as forest-line or shrub advancement affecting carbon and nutrient transport into lakes, act on considerably longer time-scales. This study therefore emphasizes the recurring challenge for ecological climate change studies related to species interactions within and across ecosystem compartments and the response time of ecosystems.

Forecasting of hourly load by pattern recognition in a small area power system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dehdashti-Shahrokh, A.

1982-01-01

An intuitive, logical, simple and efficient method of forecasting hourly load in a small area power system is presented. A pattern recognition approach is used in developing the forecasting model. Pattern recognition techniques are powerful tools in the field of artificial intelligence (cybernetics) and simulate the way the human brain operates to make decisions. Pattern recognition is generally used in analysis of processes where the total physical nature behind the process variation is unkown but specific kinds of measurements explain their behavior. In this research basic multivariate analyses, in conjunction with pattern recognition techniques, are used to develop a linearmore » deterministic model to forecast hourly load. This method assumes that load patterns in the same geographical area are direct results of climatological changes (weather sensitive load), and have occurred in the past as a result of similar climatic conditions. The algorithm described in here searches for the best possible pattern from a seasonal library of load and weather data in forecasting hourly load. To accommodate the unpredictability of weather and the resulting load, the basic twenty-four load pattern was divided into eight three-hour intervals. This division was made to make the model adaptive to sudden climatic changes. The proposed method offers flexible lead times of one to twenty-four hours. The results of actual data testing had indicated that this proposed method is computationally efficient, highly adaptive, with acceptable data storage size and accuracy that is comparable to many other existing methods.« less

78 FR 13874 - Watershed Modeling To Assess the Sensitivity of Streamflow, Nutrient, and Sediment Loads to...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-03-01

... an improved understanding of methodological challenges associated with integrating existing tools and... methodological challenges associated with integrating existing tools (e.g., climate models, downscaling... sensitivity to methodological choices such as different approaches for downscaling global climate change...

Flexible Residential Test Facility: Impact of Infiltration and Ventilation on Measured Cooling Season Energy and Moisture Levels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Parker, Danny S.; Cummings, Jamie E.; Vieira, Robin K.

Air infiltration and ventilation in residential buildings is a very large part of the heating loads, but empirical data regarding the impact on space cooling has been lacking. Moreover, there has been little data on how building tightness might relate to building interior moisture levels in homes in a hot and humid climate. To address this need, BA-PIRC has conducted research to assess the moisture and cooling load impacts of airtightness and mechanical ventilation in two identical laboratory homes in the hot-humid climate over the cooling season.

Timing and climate forcing of volcanic eruptions for the past 2,500 years.

PubMed

Sigl, M; Winstrup, M; McConnell, J R; Welten, K C; Plunkett, G; Ludlow, F; Büntgen, U; Caffee, M; Chellman, N; Dahl-Jensen, D; Fischer, H; Kipfstuhl, S; Kostick, C; Maselli, O J; Mekhaldi, F; Mulvaney, R; Muscheler, R; Pasteris, D R; Pilcher, J R; Salzer, M; Schüpbach, S; Steffensen, J P; Vinther, B M; Woodruff, T E

2015-07-30

Volcanic eruptions contribute to climate variability, but quantifying these contributions has been limited by inconsistencies in the timing of atmospheric volcanic aerosol loading determined from ice cores and subsequent cooling from climate proxies such as tree rings. Here we resolve these inconsistencies and show that large eruptions in the tropics and high latitudes were primary drivers of interannual-to-decadal temperature variability in the Northern Hemisphere during the past 2,500 years. Our results are based on new records of atmospheric aerosol loading developed from high-resolution, multi-parameter measurements from an array of Greenland and Antarctic ice cores as well as distinctive age markers to constrain chronologies. Overall, cooling was proportional to the magnitude of volcanic forcing and persisted for up to ten years after some of the largest eruptive episodes. Our revised timescale more firmly implicates volcanic eruptions as catalysts in the major sixth-century pandemics, famines, and socioeconomic disruptions in Eurasia and Mesoamerica while allowing multi-millennium quantification of climate response to volcanic forcing.

Timing and climate forcing of volcanic eruptions for the past 2,500 years

NASA Astrophysics Data System (ADS)

Sigl, M.; Winstrup, M.; McConnell, J. R.; Welten, K. C.; Plunkett, G.; Ludlow, F.; Büntgen, U.; Caffee, M.; Chellman, N.; Dahl-Jensen, D.; Fischer, H.; Kipfstuhl, S.; Kostick, C.; Maselli, O. J.; Mekhaldi, F.; Mulvaney, R.; Muscheler, R.; Pasteris, D. R.; Pilcher, J. R.; Salzer, M.; Schüpbach, S.; Steffensen, J. P.; Vinther, B. M.; Woodruff, T. E.

2015-07-01

Volcanic eruptions contribute to climate variability, but quantifying these contributions has been limited by inconsistencies in the timing of atmospheric volcanic aerosol loading determined from ice cores and subsequent cooling from climate proxies such as tree rings. Here we resolve these inconsistencies and show that large eruptions in the tropics and high latitudes were primary drivers of interannual-to-decadal temperature variability in the Northern Hemisphere during the past 2,500 years. Our results are based on new records of atmospheric aerosol loading developed from high-resolution, multi-parameter measurements from an array of Greenland and Antarctic ice cores as well as distinctive age markers to constrain chronologies. Overall, cooling was proportional to the magnitude of volcanic forcing and persisted for up to ten years after some of the largest eruptive episodes. Our revised timescale more firmly implicates volcanic eruptions as catalysts in the major sixth-century pandemics, famines, and socioeconomic disruptions in Eurasia and Mesoamerica while allowing multi-millennium quantification of climate response to volcanic forcing.

[Climate and ecologic state of urban areas in Eastern Kazakhstan].

PubMed

Onaev, S T; Grebeneva, O V; Shadetova, A Zh; Kurmangalieva, D S; Balaeva, E A

2011-01-01

Ust-Kamenogorsk territory was demonstrated to have climate peculiarities depending on local relief and unfavorable wind conditions of ventilation, that could promote formation of highly chemically loaded zones. Suggested evaluation methods provide qualitative and quantitative assessment of climate parameters for individual areas of residence. Marking areas according to residence comfort for population, based on analysis of geographic position of the studied territory, in accordance with repetition of meteorologic processes, could specify major factors influencing climate on urban territories of modem Kazakhstan cities.

Topographically driven differences in energy and water constrain climatic control on forest carbon sequestration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Swetnam, Tyson L.; Brooks, Paul D.; Barnard, Holly R.

Mountains are vital to ecosystems and human society given their influence on global carbon and water cycles. Yet the extent to which topography regulates montane forest carbon uptake and storage remains poorly understood. To address this knowledge gap, we compared forest aboveground carbon loading to topographic metrics describing energy balance and water availability across three headwater catchments of the Boulder Creek Watershed, Colorado, USA. The catchments range from 1800 to 3500 m above mean sea level with 46–102 cm/yr mean annual precipitation and -1.2° to 12.3°C mean annual temperature. In all three catchments, we found mean forest carbon loading consistentlymore » increased from ridges (27 ± 19 Mg C ha) to valley bottoms (60 ± 28 Mg C ha). Low topographic positions held up to 185 ± 76 Mg C ha, more than twice the peak value of upper positions. Toe slopes fostered disproportionately high net carbon uptake relative to other topographic positions. Carbon storage was on average 20–40 Mg C ha greater on north to northeast aspects than on south to southwest aspects, a pattern most pronounced in the highest elevation, coldest and wettest catchment. Both the peak and mean aboveground carbon storage of the three catchments, crossing an 11°C range in temperature and doubling of local precipitation, defied the expectation of an optimal elevation-gradient climatic zone for net primary production. These results have important implications for models of forest sensitivity to climate change, as well as to predicted estimates of continental carbon reservoirs.« less

Topographically driven differences in energy and water constrain climatic control on forest carbon sequestration

DOE PAGES

Swetnam, Tyson L.; Brooks, Paul D.; Barnard, Holly R.; ...

2017-04-21

Mountains are vital to ecosystems and human society given their influence on global carbon and water cycles. Yet the extent to which topography regulates montane forest carbon uptake and storage remains poorly understood. To address this knowledge gap, we compared forest aboveground carbon loading to topographic metrics describing energy balance and water availability across three headwater catchments of the Boulder Creek Watershed, Colorado, USA. The catchments range from 1800 to 3500 m above mean sea level with 46–102 cm/yr mean annual precipitation and -1.2° to 12.3°C mean annual temperature. In all three catchments, we found mean forest carbon loading consistentlymore » increased from ridges (27 ± 19 Mg C ha) to valley bottoms (60 ± 28 Mg C ha). Low topographic positions held up to 185 ± 76 Mg C ha, more than twice the peak value of upper positions. Toe slopes fostered disproportionately high net carbon uptake relative to other topographic positions. Carbon storage was on average 20–40 Mg C ha greater on north to northeast aspects than on south to southwest aspects, a pattern most pronounced in the highest elevation, coldest and wettest catchment. Both the peak and mean aboveground carbon storage of the three catchments, crossing an 11°C range in temperature and doubling of local precipitation, defied the expectation of an optimal elevation-gradient climatic zone for net primary production. These results have important implications for models of forest sensitivity to climate change, as well as to predicted estimates of continental carbon reservoirs.« less

Optimal selection and placement of green infrastructure to reduce impacts of land use change and climate change on hydrology and water quality: An application to the Trail Creek Watershed, Indiana.

PubMed

Liu, Yaoze; Theller, Lawrence O; Pijanowski, Bryan C; Engel, Bernard A

2016-05-15

The adverse impacts of urbanization and climate change on hydrology and water quality can be mitigated by applying green infrastructure practices. In this study, the impacts of land use change and climate change on hydrology and water quality in the 153.2 km(2) Trail Creek watershed located in northwest Indiana were estimated using the Long-Term Hydrologic Impact Assessment-Low Impact Development 2.1 (L-THIA-LID 2.1) model for the following environmental concerns: runoff volume, Total Suspended Solids (TSS), Total Phosphorous (TP), Total Kjeldahl Nitrogen (TKN), and Nitrate+Nitrite (NOx). Using a recent 2001 land use map and 2050 land use forecasts, we found that land use change resulted in increased runoff volume and pollutant loads (8.0% to 17.9% increase). Climate change reduced runoff and nonpoint source pollutant loads (5.6% to 10.2% reduction). The 2050 forecasted land use with current rainfall resulted in the largest runoff volume and pollutant loads. The optimal selection and placement of green infrastructure practices using L-THIA-LID 2.1 model were conducted. Costs of applying green infrastructure were estimated using the L-THIA-LID 2.1 model considering construction, maintenance, and opportunity costs. To attain the same runoff volume and pollutant loads as in 2001 land uses for 2050 land uses, the runoff volume, TSS, TP, TKN, and NOx for 2050 needed to be reduced by 10.8%, 14.4%, 13.1%, 15.2%, and 9.0%, respectively. The corresponding annual costs of implementing green infrastructure to achieve the goals were $2.1, $0.8, $1.6, $1.9, and $0.8 million, respectively. Annual costs of reducing 2050 runoff volume/pollutant loads were estimated, and results show green infrastructure annual cost greatly increased for larger reductions in runoff volume and pollutant loads. During optimization, the most cost-efficient green infrastructure practices were selected and implementation levels increased for greater reductions of runoff and nonpoint source pollutants. Copyright © 2016 Elsevier B.V. All rights reserved.

Using satellite fire detection to calibrate components of the fire weather index system in Malaysia and Indonesia.

PubMed

Dymond, Caren C; Field, Robert D; Roswintiarti, Orbita; Guswanto

2005-04-01

Vegetation fires have become an increasing problem in tropical environments as a consequence of socioeconomic pressures and subsequent land-use change. In response, fire management systems are being developed. This study set out to determine the relationships between two aspects of the fire problems in western Indonesia and Malaysia, and two components of the Canadian Forest Fire Weather Index System. The study resulted in a new method for calibrating components of fire danger rating systems based on satellite fire detection (hotspot) data. Once the climate was accounted for, a problematic number of fires were related to high levels of the Fine Fuel Moisture Code. The relationship between climate, Fine Fuel Moisture Code, and hotspot occurrence was used to calibrate Fire Occurrence Potential classes where low accounted for 3% of the fires from 1994 to 2000, moderate accounted for 25%, high 26%, and extreme 38%. Further problems arise when there are large clusters of fires burning that may consume valuable land or produce local smoke pollution. Once the climate was taken into account, the hotspot load (number and size of clusters of hotspots) was related to the Fire Weather Index. The relationship between climate, Fire Weather Index, and hotspot load was used to calibrate Fire Load Potential classes. Low Fire Load Potential conditions (75% of an average year) corresponded with 24% of the hotspot clusters, which had an average size of 30% of the largest cluster. In contrast, extreme Fire Load Potential conditions (1% of an average year) corresponded with 30% of the hotspot clusters, which had an average size of 58% of the maximum. Both Fire Occurrence Potential and Fire Load Potential calibrations were successfully validated with data from 2001. This study showed that when ground measurements are not available, fire statistics derived from satellite fire detection archives can be reliably used for calibration. More importantly, as a result of this work, Malaysia and Indonesia have two new sources of information to initiate fire prevention and suppression activities.

Critical acid load limits in a changing climate: implications and solutions

Treesearch

Steven G. McNulty

2010-01-01

The federal agencies of the United States are currently developing guidelines for critical nitrogen load limits for U.S. forest ecosystems. These guidelines will be used to develop regulations designed to maintain pollutant inputs below the level shown to damage specified ecosystems.

A novel integrated modelling framework to assess the impacts of climate and socio-economic drivers on land use and water quality.

PubMed

Zessner, Matthias; Schönhart, Martin; Parajka, Juraj; Trautvetter, Helene; Mitter, Hermine; Kirchner, Mathias; Hepp, Gerold; Blaschke, Alfred Paul; Strenn, Birgit; Schmid, Erwin

2017-02-01

Changes in climatic conditions will directly affect the quality and quantity of water resources. Further on, they will affect them indirectly through adaptation in land use which ultimately influences diffuse nutrient emissions to rivers and therefore potentially the compliance with good ecological status according to the EU Water Framework Directive (WFD). We present an integrated impact modelling framework (IIMF) to track and quantify direct and indirect pollution impacts along policy-economy-climate-agriculture-water interfaces. The IIMF is applied to assess impacts of climatic and socio-economic drivers on agricultural land use (crop choices, farming practices and fertilization levels), river flows and the risk for exceedance of environmental quality standards for determination of the ecological water quality status in Austria. This article also presents model interfaces as well as validation procedures and results of single models and the IIMF with respect to observed state variables such as land use, river flow and nutrient river loads. The performance of the IIMF for calculations of river nutrient loads (120 monitoring stations) shows a Nash-Sutcliffe Efficiency of 0.73 for nitrogen and 0.51 for phosphorus. Most problematic is the modelling of phosphorus loads in the alpine catchments dominated by forests and mountainous landscape. About 63% of these catchments show a deviation between modelled and observed loads of 30% and more. In catchments dominated by agricultural production, the performance of the IIMF is much better as only 30% of cropland and 23% of permanent grassland dominated areas have a deviation of >30% between modelled and observed loads. As risk of exceedance of environmental quality standards is mainly recognized in catchments dominated by cropland, the IIMF is well suited for assessing the nutrient component of the WFD ecological status. Copyright © 2016 British Geological Survey, NERC. Published by Elsevier B.V. All rights reserved.

Combined impacts of current and future dust deposition and regional warming on Colorado River Basin snow dynamics and hydrology

USGS Publications Warehouse

Deems, Jeffrey S.; Painter, Thomas H.; Barsugli, Joseph J.; Belnap, Jayne; Udall, Bradley

2013-01-01

The Colorado River provides water to 40 million people in seven western states and two countries and to 5.5 million irrigated acres. The river has long been overallocated. Climate models project runoff losses of 5–20% from the basin by mid-21st century due to human-induced climate change. Recent work has shown that decreased snow albedo from anthropogenic dust loading to the CO mountains shortens the duration of snow cover by several weeks relative to conditions prior to western expansion of the US in the mid-1800s, and advances peak runoff at Lees Ferry, Arizona, by an average of 3 weeks. Increases in evapotranspiration from earlier exposure of soils and germination of plants have been estimated to decrease annual runoff by more than 1.0 billion cubic meters, or ~5% of the annual average. This prior work was based on observed dust loadings during 2005–2008; however, 2009 and 2010 saw unprecedented levels of dust loading on snowpacks in the Upper Colorado River Basin (UCRB), being on the order of 5 times the 2005–2008 loading. Building on our prior work, we developed a new snow albedo decay parameterization based on observations in 2009/10 to mimic the radiative forcing of extreme dust deposition. We convolve low, moderate, and extreme dust/snow albedos with both historic climate forcing and two future climate scenarios via a delta method perturbation of historic records. Compared to moderate dust, extreme dust absorbs 2× to 4× the solar radiation, and shifts peak snowmelt an additional 3 weeks earlier to a total of 6 weeks earlier than pre-disturbance. The extreme dust scenario reduces annual flow volume an additional 1% (6% compared to pre-disturbance), a smaller difference than from low to moderate dust scenarios due to melt season shifting into a season of lower evaporative demand. The sensitivity of flow timing to dust radiative forcing of snow albedo is maintained under future climate scenarios, but the sensitivity of flow volume reductions decreases with increased climate forcing. These results have implications for water management and suggest that dust abatement efforts could be an important component of any climate adaptation strategies in the UCRB.

An integrated modelling methodology to study the impacts of nutrients on coastal aquatic ecosystems in the context of climate change

NASA Astrophysics Data System (ADS)

Pesce, Marco; Critto, Andrea; Torresan, Silvia; Santini, Monia; Giubilato, Elisa; Pizzol, Lisa; Mercogliano, Paola; Zirino, Alberto; Wei, Ouyang; Marcomini, Antonio

2017-04-01

It has been recognized that the increase of atmospheric greenhouse gases (GHG) due to anthropogenic activities is causing changes in Earth's climate. Global mean temperatures are expected to rise by 0.3 to 4.8 °C by the end of the 21st century, and the water cycle to alter because of changes in global atmospheric moisture. Coastal waterbodies such as estuaries, bays and lagoons together with the ecological and socio-economic services they provide, could be among those most affected by the ongoing changes on climate. Because of their position at the land-sea interface, they are subjected to the combined changes in the physico-chemical processes of atmosphere, upstream land and coastal waters. Particularly, climate change is expected to alter phytoplankton communities by changing their climate and environmental drivers, such as temperature, precipitation, wind, solar radiation and nutrient loadings, and to exacerbate the symptoms of eutrophication events, such as hypoxia, harmful algal blooms (HAB) and loss of habitat. A better understanding of the links between climate-related drivers and phytoplankton is therefore necessary for predicting climate change impacts on aquatic ecosystems. In this context, the integration of climate scenarios and environmental models can become a valuable tool for the investigation and prediction of phytoplankton ecosystem dynamics under climate change conditions. In the last decade, the effects of climate change on the environmental distribution of nutrients and the resulting effects on aquatic ecosystems encouraged the conduction of modeling studies at a catchment scale, even though mainly are related to lake ecosystem. The further development of integrated modeling approaches and their application to other types of waterbodies such as coastal waters can be a useful contribution to increase the availability of management tools for ecological conservation and adaptation policies. Here we present the case study of the Zero river basin in Italy, one of the main contributors of freshwater and nutrients loadings to the salt-marsh Palude di Cona, a waterbody belonging to the lagoon of Venice. To predict the effects of climate change on nutrient loadings and their effects on the phytoplankton community of the receiving waterbody, we applied a methodology integrating an ensemble of GCM-RCM climate projections, the hydrological model SWAT and the ecological model AQUATOX. Climate scenarios for the study area revealed an increase of precipitations in the winter period and a decrease in the summer months, while temperature shows a significant increase over the whole year. The hydrological model SWAT predicted changes the Zero river's waterflow and nutrients' loadings. Both parameters show a tendency to increase in the winter period, and a reduction during the summer months. Simulations with AQUATOX predicted changes in the concentration of nutrients in the salt-marsh Palude di Cona, and variations in the biomass and species of the phytoplankton community. The simulation shows changes are highly species-dependent. Major changes are observed in the spring-summer period, where the abundance of warm-adapted species increase noticeably.

40 CFR 264.573 - Design and operating requirements.

Code of Federal Regulations, 2013 CFR

2013-07-01

..., climatic conditions, the stress of daily operations, e.g., variable and moving loads such as vehicle... leakage to which they are exposed, climatic conditions, the stress of installation, and the stress of daily operation (including stresses from vehicular traffic on the drip pad); (ii) Placed upon a...

40 CFR 264.573 - Design and operating requirements.

Code of Federal Regulations, 2014 CFR

2014-07-01

..., climatic conditions, the stress of daily operations, e.g., variable and moving loads such as vehicle... leakage to which they are exposed, climatic conditions, the stress of installation, and the stress of daily operation (including stresses from vehicular traffic on the drip pad); (ii) Placed upon a...

40 CFR 264.573 - Design and operating requirements.

Code of Federal Regulations, 2012 CFR

2012-07-01

..., climatic conditions, the stress of daily operations, e.g., variable and moving loads such as vehicle... leakage to which they are exposed, climatic conditions, the stress of installation, and the stress of daily operation (including stresses from vehicular traffic on the drip pad); (ii) Placed upon a...

Vulnerability of boreal zone for increased nitrogen loading due to climate change

NASA Astrophysics Data System (ADS)

Rankinen, Katri; Holmberg, Maria

2016-04-01

The observed rapid warming of the boreal zone that has been observed in Finland (0.14 °C by decade) is expected to continue (http://www.ipcc.ch/report/ar5/wg1/). Also precipitation is assumed to increase in future. These changes may increase nitrogen (N) loading from terrestrial environments to water bodies by accelerating soil organic matter decay and by increasing runoff. Nitrogen is limiting nutrient in the Baltic Sea but also in some lakes, so increased loading may increase eutrophication. Further, high nitrate levels in drinking water may cause methaemoglobin anemia for humans, and nitrate is also connected to increased risk of diabetes and cancer. Thus EU has set upper limits to nitrate concentration in drinking water. MONIMET (LIFE12 ENV/FI/000409) is a project about Climate Change Indicators and Vulnerability of Boreal Zone. We simulated N loading from two boreal catchments to the receiving waters by the dynamic, catchment scale model INCA in different climate change and land use change scenarios. We calculated land use specific N loading values for these two well monitored catchments that belong to the LTER (The Long Term Ecological Research) monitoring network. We upscaled the results to the larger river basin, combining them with the information on drinking water supply to assess the vulnerability. Specific emphasis was paid on nitrate concentrations in soil water and groundwater. In general, land use change has higher influence on N loading than increase in precipitation and temperature alone. Peak runoff will sift from snow melting peak in April to late autumn and winter. Growing season will become longer allowing more efficient vegetation uptake of nutrients. Small groundwater aquifers and private wells in the middle of agricultural fields will be in the risk of increased N concentrations, if agricultural N loading increases due to changes in agricultural patterns and land use change.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rice, C Keith; Uselton, Robert B.; Shen, Bo

A residential-sized dual air-source integrated heat pump (AS-IHP) concept is under development in partnership between ORNL and a manufacturer. The concept design consists of a two-stage air-source heat pump (ASHP) coupled on the air distribution side with a separate novel water heating/dehumidification (WH/DH) module. The motivation for this unusual equipment combination is the forecast trend for home sensible loads to be reduced more than latent loads. Integration of water heating with a space dehumidification cycle addresses humidity control while performing double-duty. This approach can be applied to retrofit/upgrade applications as well as new construction. A WH/DH module capable of ~1.47more » L/h water removal and ~2 kW water heating capacity was assembled by the manufacturer. A heat pump system model was used to guide the controls design; lab testing was conducted and used to calibrate the models. Performance maps were generated and used in a TRNSYS sub-hourly simulation to predict annual performance in a well-insulated house. Annual HVAC/WH energy savings of ~35% are predicted in cold and hot-humid U.S. climates compared to a minimum efficiency baseline.« less

Quantitative Models for Ecosystem Assessment in Narragansett Bay: Response to Nutrient Loading and Other Stressors

EPA Science Inventory

Multiple drivers, including nutrient loading and climate change, affect the Narragansett Bay ecosystem. Managers are interested in understanding the timing and magnitude of these effects, as well as ecosystem responses to restoration actions, such as the capacity and potential fo...

Variable climatic conditions dominate recent phytoplankton dynamics in Chesapeake Bay

NASA Astrophysics Data System (ADS)

Harding, Lawrence W., Jr.; Mallonee, Michael E.; Perry, Elgin S.; Miller, W. David; Adolf, Jason E.; Gallegos, Charles L.; Paerl, Hans W.

2016-03-01

Variable climatic conditions strongly influence phytoplankton dynamics in estuaries globally. Our study area is Chesapeake Bay, a highly productive ecosystem providing natural resources, transportation, and recreation for nearly 16 million people inhabiting a 165,000-km2 watershed. Since World War II, nutrient over-enrichment has led to multiple ecosystem impairments caused by increased phytoplankton biomass as chlorophyll-a (chl-a). Doubled nitrogen (N) loadings from 1945-1980 led to increased chl-a, reduced water clarity, and low dissolved oxygen (DO), while decreased N loadings from 1981-2012 suggest modest improvement. The recent 30+ years are characterized by high inter-annual variability of chl-a, coinciding with irregular dry and wet periods, complicating the detection of long-term trends. Here, we synthesize time-series data for historical and recent N loadings (TN, NO2 + NO3), chl-a, floral composition, and net primary productivity (NPP) to distinguish secular changes caused by nutrient over-enrichment from spatio-temporal variability imposed by climatic conditions. Wet years showed higher chl-a, higher diatom abundance, and increased NPP, while dry years showed lower chl-a, lower diatom abundance, and decreased NPP. Our findings support a conceptual model wherein variable climatic conditions dominate recent phytoplankton dynamics against a backdrop of nutrient over-enrichment, emphasizing the need to separate these effects to gauge progress toward improving water quality in estuaries.

Variable climatic conditions dominate recent phytoplankton dynamics in Chesapeake Bay.

PubMed

Harding, Lawrence W; Mallonee, Michael E; Perry, Elgin S; Miller, W David; Adolf, Jason E; Gallegos, Charles L; Paerl, Hans W

2016-03-30

Variable climatic conditions strongly influence phytoplankton dynamics in estuaries globally. Our study area is Chesapeake Bay, a highly productive ecosystem providing natural resources, transportation, and recreation for nearly 16 million people inhabiting a 165,000-km(2) watershed. Since World War II, nutrient over-enrichment has led to multiple ecosystem impairments caused by increased phytoplankton biomass as chlorophyll-a (chl-a). Doubled nitrogen (N) loadings from 1945-1980 led to increased chl-a, reduced water clarity, and low dissolved oxygen (DO), while decreased N loadings from 1981-2012 suggest modest improvement. The recent 30+ years are characterized by high inter-annual variability of chl-a, coinciding with irregular dry and wet periods, complicating the detection of long-term trends. Here, we synthesize time-series data for historical and recent N loadings (TN, NO2 + NO3), chl-a, floral composition, and net primary productivity (NPP) to distinguish secular changes caused by nutrient over-enrichment from spatio-temporal variability imposed by climatic conditions. Wet years showed higher chl-a, higher diatom abundance, and increased NPP, while dry years showed lower chl-a, lower diatom abundance, and decreased NPP. Our findings support a conceptual model wherein variable climatic conditions dominate recent phytoplankton dynamics against a backdrop of nutrient over-enrichment, emphasizing the need to separate these effects to gauge progress toward improving water quality in estuaries.

Variable climatic conditions dominate recent phytoplankton dynamics in Chesapeake Bay

PubMed Central

Harding, Jr., Lawrence W.; Mallonee, Michael E.; Perry, Elgin S.; Miller, W. David; Adolf, Jason E.; Gallegos, Charles L.; Paerl, Hans W.

2016-01-01

Variable climatic conditions strongly influence phytoplankton dynamics in estuaries globally. Our study area is Chesapeake Bay, a highly productive ecosystem providing natural resources, transportation, and recreation for nearly 16 million people inhabiting a 165,000-km2 watershed. Since World War II, nutrient over-enrichment has led to multiple ecosystem impairments caused by increased phytoplankton biomass as chlorophyll-a (chl-a). Doubled nitrogen (N) loadings from 1945–1980 led to increased chl-a, reduced water clarity, and low dissolved oxygen (DO), while decreased N loadings from 1981–2012 suggest modest improvement. The recent 30+ years are characterized by high inter-annual variability of chl-a, coinciding with irregular dry and wet periods, complicating the detection of long-term trends. Here, we synthesize time-series data for historical and recent N loadings (TN, NO2 + NO3), chl-a, floral composition, and net primary productivity (NPP) to distinguish secular changes caused by nutrient over-enrichment from spatio-temporal variability imposed by climatic conditions. Wet years showed higher chl-a, higher diatom abundance, and increased NPP, while dry years showed lower chl-a, lower diatom abundance, and decreased NPP. Our findings support a conceptual model wherein variable climatic conditions dominate recent phytoplankton dynamics against a backdrop of nutrient over-enrichment, emphasizing the need to separate these effects to gauge progress toward improving water quality in estuaries. PMID:27026279

Influence of coatings on the thermal and mechanical processes at insulating glass units

NASA Astrophysics Data System (ADS)

Penkova, Nina; Krumov, Kalin; Surleva, Andriana; Geshkova, Zlatka

2017-09-01

Different coatings on structural glass are used in the advances transparent facades and window systems in order to increase the thermal performance of the glass units and to regulate their optical properties. Coated glass has a higher absorptance in the solar spectrum which leads to correspondent higher temperature in the presence of solar load compared to the uncoated one. That process results in higher climatic loads at the insulating glass units (IGU) and in thermal stresses in the coated glass elements. Temperature fields and gradients in glass panes and climatic loads at IGU in window systems are estimated at different coating of glazed system. The study is implemented by numerical simulation of conjugate heat transfer in the window systems at summer time and presence of solar irradiation, as well as during winter night time.

Improving Thermal Performance of a Residential Building, Related to Its Orientations - A Case Study

NASA Astrophysics Data System (ADS)

Akshaya, S.; Harish, S.; Arthy, R.; Muthu, D.; Venkatasubramanian, C.

2017-07-01

Urban planners and stakeholders require knowledge about the effectiveness of city-scale climate adaptation measures in order to develop climate resilient cities and to push forward the political process for the implementation of climate adaptation strategies. This study examines the impact of modifications in orientation of buildings with respect to heat load. Heat load calculation is a mathematical process to determine the best capacity, application and style of HVAC system. The purpose is to ensure energy efficiency while also maximizing comfort inside the building. This study of load calculation is essential for a building because it helps to pick the best orientation and focuses to find an orientation that will reduce energy due to direct solar radiation. One of the factors affecting this assessment is the latitude of the location. The heat gain is effective through walls and fenestration. Improper management through ineffective orientation of the building’s natural heat gain leads to excessive consumption of energy in the form of CL. The total heat gain for the above factors is calculated with the equations and assumptions as per ASHRAE code. After the calculation of heat load for different orientations, the best suited orientation of the building is found. By altering the building to suitable orientation, the dependence on electrical equipment can be minimized and thereby helps in energy conservation.

How phosphorus limitation can control climate-active gas sources and sinks

NASA Astrophysics Data System (ADS)

Gypens, Nathalie; Borges, Alberto V.; Ghyoot, Caroline

2017-06-01

Since the 1950's, anthropogenic activities have increased nutrient river loads to European coastal areas. Subsequent implementation of nutrient reduction policies have led to considerably reduction of phosphorus (P) loads from the mid-1980's, while nitrogen (N) loads were maintained, inducing a P limitation of phytoplankton growth in many eutrophied coastal areas such as the Southern Bight of the North Sea (SBNS). When dissolved inorganic phosphorus (DIP) is limiting, most phytoplankton organisms are able to indirectly acquire P from dissolved organic P (DOP). We investigate the impact of DOP use on phytoplankton production and atmospheric fluxes of CO2 and dimethylsulfide (DMS) in the SBNS from 1951 to 2007 using an extended version of the R-MIRO-BIOGAS model. This model includes a description of the ability of phytoplankton organisms to use DOP as a source of P. Results show that primary production can increase up to 30% due to DOP uptake under limiting DIP conditions. Consequently, simulated DMS emissions also increase proportionally while CO2 emissions to the atmosphere decrease, relative to the reference simulation without DOP uptake.

The effects of emission control strategies on light-absorbing carbon emissions from a modern heavy-duty diesel engine.

PubMed

Robinson, Michael A; Olson, Michael R; Liu, Z Gerald; Schauer, James J

2015-06-01

Control of atmospheric black carbon (BC) and brown carbon (BrC) has been proposed as an important pathway to climate change mitigation, but sources of BC and BrC are still not well understood. In order to better identify the role of modern heavy-duty diesel engines on the production of BC and BrC, emissions from a heavy-duty diesel engine operating with different emission control strategies were examined using a source dilution sampling system. The effect of a diesel oxidation catalyst (DOC) and diesel particulate filter (DPF) on light-absorbing carbon (LAC) was evaluated at three steady-state engine operation modes: idle, 50% speed and load, and 100% speed and load. LAC was measured with four different engine configurations: engine out, DOC out, DPF out, and engine out with an altered combustion calibration. BC and BrC emission rates were measured with the Aethalometer (AE-31). EC and BC emission rates normalized to the mass of CO₂emitted increased with increasing engine speed and load. Emission rates normalized to brake-specific work did not exhibit similar trends with speed and load, but rather the highest emission rate was measured at idle. EC and OC emissions were reduced by 99% when the DOC and DPF architecture was applied. The application of a DPF was equally effective at removing 99% of the BC fraction of PM, proving to be an important control strategy for both LAC and PM. BC emissions were unexpectedly increased across the DOC, seemingly due to a change aerosol optical properties. Removal of exhaust gas recirculation (EGR) flow due to simulated EGR cooler failure caused a large increase in OC and BrC emission rates at idle, but had limited influence during high load operation. LAC emissions proved to be sensitive to the same control strategies effective at controlling the total mass of diesel PM. In the context of black carbon emissions, very small emission rates of brown carbon were measured over a range of control technologies and engine operating conditions. During specific idle engine operation without EGR and adjusted fueling conditions, brown carbon can be formed in significant amounts, requiring careful management tactics. Control technologies for particulate matter are very effective for light-absorbing carbon, reducing black carbon emissions to near zero for modern engines equipped with a DPF. Efforts to control atmospheric brown carbon need to focus on other sources other than modern diesel engines, such as biomass burning.

Wildfires threaten mercury stocks in northern soils

USGS Publications Warehouse

Turetsky, M.R.; Harden, J.W.; Friedli, H.R.; Flannigan, M.; Payne, N.; Crock, J.; Radke, L.

2006-01-01

With climate change rapidly affecting northern forests and wetlands, mercury reserves once protected in cold, wet soils are being exposed to burning, likely triggering large releases of mercury to the atmosphere. We quantify organic soil mercury stocks and burn areas across western, boreal Canada for use in fire emission models that explore controls of burn area, consumption severity, and fuel loading on atmospheric mercury emissions. Though renowned as hotspots for the accumulation of mercury and its transformation to the toxic methylmercury, boreal wetlands might soon transition to hotspots for atmospheric mercury emissions. Estimates of circumboreal mercury emissions from this study are 15-fold greater than estimates that do not account for mercury stored in peat soils. Ongoing and projected increases in boreal wildfire activity due to climate change will increase atmospheric mercury emissions, contributing to the anthropogenic alteration of the global mercury cycle and exacerbating mercury toxicities for northern food chains. Copyright 2006 by the American Geophysical Union.

CLIMATE CHANGE AND EUTROPHICATION RESPONSES IN THE POTOMAC ESTUARY AND CHESAPEAKE BAY

EPA Science Inventory

Our analysis of tree ring and sediment core data indicates that climate variability in the 1900s had different consequences in the Potomac Estuary and Chesapeake Bay than in the previous two centuries as a result of anthropogenic activity affecting nutrient loadings in associated...

THE ROLES OF ANTHROPOGENIC WATERSHED LOADING AND CLIMATE VARIABILITY ON NITROGEN FLUXES TO THE POTOMAC RIVER ESTUARY

EPA Science Inventory

To better anticipate responses of estuaries and coastal ecosystems to human activity and climate variation, it is useful to examine the historical record of nitrogen fluxes from watersheds to receiving waters and the factors affecting them. This study undertook a statistical exam...

FEASIBILITY STUDY OF CLIMATE CHANGE IMPACTS ON NITROGEN IN CAPE COD EMBAYMENTS

EPA Science Inventory

The objective of this study is to explore the feasibility of studying potential effects of climate change on impairments resulting from nitrogen loadings in the salt water embayments of Cape Cod. The report includes a recommended plan for studying these impacts, an estimate of t...

The influence of climate, nutrient loading and predation on spatial and temporal changes in fish assemblages in Narragansett Bay

EPA Science Inventory

Estuarine fish are a highly valued resources that are affected by several factors, including climate, trophic interactions, pollution, and fishing pressure. Here, we examine the spatial and temporal patterns in estuarine fish assemblage in Narragansett Bay, an estuary located in...

Predicting the Impacts of Climate Change on Runoff and Sediment Processes in Agricultural Watersheds: A Case Study from the Sunflower Watershed in the Lower Mississippi Basin

NASA Astrophysics Data System (ADS)

Elkadiri, R.; Momm, H.; Yasarer, L.; Armour, G. L.

2017-12-01

Climatic conditions play a major role in physical processes impacting soil and agrochemicals detachment and transportation from/in agricultural watersheds. In addition, these climatic conditions are projected to significantly vary spatially and temporally in the 21st century, leading to vast uncertainties about the future of sediment and non-point source pollution transport in agricultural watersheds. In this study, we selected the sunflower basin in the lower Mississippi River basin, USA to contribute in the understanding of how climate change affects watershed processes and the transport of pollutant loads. The climate projections used in this study were retrieved from the archive of World Climate Research Programme's (WCRP) Coupled Model Intercomparison Phase 5 (CMIP5) project. The CMIP5 dataset was selected because it contains the most up-to-date spatially downscaled and bias corrected climate projections. A subset of ten GCMs representing a range in projected climate were spatially downscaled for the sunflower watershed. Statistics derived from downscaled GCM output representing the 2011-2040, 2041-2070 and 2071-2100 time periods were used to generate maximum/minimum temperature and precipitation on a daily time step using the USDA Synthetic Weather Generator, SYNTOR. These downscaled climate data were then utilized as inputs to run in the Annualized Agricultural Non-Point Source (AnnAGNPS) pollution watershed model to estimate time series of runoff, sediment, and nutrient loads produced from the watershed. For baseline conditions a validated simulation of the watershed was created and validated using historical data from 2000 until 2015.

Traits of surface water pollution under climate and land use changes: A remote sensing and hydrological modeling approach

NASA Astrophysics Data System (ADS)

Jordan, Yuyan C.; Ghulam, Abduwasit; Hartling, Sean

2014-01-01

In this paper, spatial and temporal trajectories of land cover/land use change (LCLUC) derived from Landsat data record are combined with hydrological modeling to explore the implication of vegetation dynamics on soil erosion and total suspended sediment (TSS) loading to surface rivers. The inter-annual coefficient of variation (CoV) of normalized difference vegetation index (NDVI) is used to screen the LCLUC and climate change. The Soil and Water Assessment Tool (SWAT) is employed to identify the monthly TSS for two times interval (1991 to 2001 and 2001 to 2011) at subbasin levels. SWAT model is calibrated from 1991 to 2001 and validated from 2002 to 2011 at three USGS gauging sites located in the study area. The Spearman's rank correlation of annual mean TSS is used to assess the temporal trends of TSS dynamics in the subbasins in the two study periods. The spatial correlation among NDVI, LCLUC, climate change and TSS loading rate changes is quantified by using linear regression model and negative/positive trend analysis. Our results showed that higher rainfall yields contribute to higher TSS loading into surface waters. A higher inter-annual accumulated vegetation index and lower inter-annual CoV distributed over the uplands resulted in a lower TSS loading rate, while a relatively low vegetation index with larger CoV observed over lowlands resulted in a higher TSS loading rate. The TSS loading rate at the basin outlet increased with the decrease of annual NDVI due to expanding urban areas in the watershed. The results also suggested nonlinearity between the trends of TSS loading with any of a specific land cover change because of the fact that the contribution of a factor can be influenced by the effects of other factors. However, dominant factors that shape the relationship between the trend of TSS loading and specific land cover changes were detected. The change of forest showed a negative relationship while agriculture and pasture demonstrated positive relationships with TSS loading change. Our results do not show any significant causal relationship between urbanization and the TSS loading change suggesting that further investigation needs to be carried out to understand the mechanism of the impact of urban sprawl on surface water quality.

Modeling Historical and Projected Future Atmospheric Nitrogen Loading to the Chesapeake Bay Watershed

EPA Science Inventory

Land use and climate change are expected to alter key processes in the Chesapeake Bay watershed and can potentially exacerbate the impact of excess nitrogen. Atmospheric sources are one of the largest loadings of nitrogen to the Chesapeake Bay watershed. In this study, we explore...

Impacts of management and climate change on nitrate leaching in a forested karst area.

PubMed

Dirnböck, Thomas; Kobler, Johannes; Kraus, David; Grote, Rüdiger; Kiese, Ralf

2016-01-01

Forest management and climate change, directly or indirectly, affect drinking water resources, both in terms of quality and quantity. In this study in the Northern Limestone Alps in Austria we have chosen model calculations (LandscapeDNDC) in order to resolve the complex long-term interactions of management and climate change and their effect on nitrogen dynamics, and the consequences for nitrate leaching from forest soils into the karst groundwater. Our study highlights the dominant role of forest management in controlling nitrate leaching. Both clear-cut and shelterwood-cut disrupt the nitrogen cycle to an extent that causes peak concentrations and high fluxes into the seepage water. While this effect is well known, our modelling approach has revealed additional positive as well as negative impacts of the expected climatic changes on nitrate leaching. First, we show that peak nitrate concentrations during post-cutting periods were elevated under all climate scenarios. The maximal effects of climatic changes on nitrate concentration peaks were 20-24 mg L(-1) in 2090 with shelterwood or clear-cut management. Second, climate change significantly decreased the cumulative nitrate losses over full forest rotation periods (by 10-20%). The stronger the expected temperature increase and precipitation decrease (in summer), the lesser were the observed nitrate losses. However, mean annual seepage water nitrate concentrations and cumulative nitrate leaching were higher under continuous forest cover management than with shelterwood-cut and clear-cut systems. Watershed management can thus be adapted to climate change by either reducing peak concentrations or long-term loads of nitrate in the karst groundwater. Copyright © 2015 Elsevier Ltd. All rights reserved.

Climate change in Brazil: perspective on the biogeochemistry of inland waters.

PubMed

Roland, F; Huszar, V L M; Farjalla, Vf; Enrich-Prast, A; Amado, A M; Ometto, J P H B

2012-08-01

Although only a small amount of the Earth's water exists as continental surface water bodies, this compartment plays an important role in the biogeochemical cycles connecting the land to the atmosphere. The territory of Brazil encompasses a dense river net and enormous number of shallow lakes. Human actions have been heavily influenced by the inland waters across the country. Both biodiversity and processes in the water are strongly driven by seasonal fluvial forces and/or precipitation. These macro drivers are sensitive to climate changes. In addition to their crucial importance to humans, inland waters are extremely rich ecosystems, harboring high biodiversity, promoting landscape equilibrium (connecting ecosystems, maintaining animal and plant flows in the landscape, and transferring mass, nutrients and inocula), and controlling regional climates through hydrological-cycle feedback. In this contribution, we describe the aquatic ecological responses to climate change in a conceptual perspective, and we then analyze the possible climate-change scenarios in different regions in Brazil. We also indentify some potential biogeochemical signals in running waters, natural lakes and man-made impoundments. The possible future changes in climate and aquatic ecosystems in Brazil are highly uncertain. Inland waters are pressured by local environmental changes because of land uses, landscape fragmentation, damming and diversion of water bodies, urbanization, wastewater load, and level of pollutants can alter biogeochemical patterns in inland waters over a shorter term than can climate changes. In fact, many intense environmental changes may enhance the effects of changes in climate. Therefore, the maintenance of key elements within the landscape and avoiding extreme perturbation in the systems are urgent to maintain the sustainability of Brazilian inland waters, in order to prevent more catastrophic future events.

Small Scale Solar Cooling Unit in Climate Conditions of Latvia: Environmental and Economical Aspects

NASA Astrophysics Data System (ADS)

Jaunzems, Dzintars; Veidenbergs, Ivars

2010-01-01

The paper contributes to the analyses from the environmental and economical point of view of small scale solar cooling system in climate conditions of Latvia. Cost analyses show that buildings with a higher cooling load and full load hours have lower costs. For high internal gains, cooling costs are around 1,7 €/kWh and 2,5 €/kWh for buildings with lower internal gains. Despite the fact that solar cooling systems have significant potential to reduce CO2 emissions due to a reduction of electricity consumption, the economic feasibility and attractiveness of solar cooling system is still low.

The role of the atmospheric electric field in the dust-lifting process

NASA Astrophysics Data System (ADS)

Esposito, F.; Molinaro, R.; Popa, C. I.; Molfese, C.; Cozzolino, F.; Marty, L.; Taj-Eddine, K.; Di Achille, G.; Franzese, G.; Silvestro, S.; Ori, G. G.

2016-05-01

Mineral dust particles represent the most abundant component of atmospheric aerosol in terms of dry mass. They play a key role in climate and climate change, so the study of their emission processes is of utmost importance. Measurements of dust emission into the atmosphere are scarce, so that the dust load is generally estimated using models. It is known that the emission process can generate strong atmospheric electric fields. Starting from the data we acquired in the Sahara desert, here, we show for the first time that depending on the relative humidity conditions, electric fields contribute to increase up to a factor of 10 the amount of particles emitted into the atmosphere. This means that electrical forces and humidity are critical quantities in the dust emission process and should be taken into account in climate and circulation models to obtain more realistic estimations of the dust load in the atmosphere.

Aerosol effects on cloud water amounts were successfully simulated by a global cloud-system resolving model.

PubMed

Sato, Yousuke; Goto, Daisuke; Michibata, Takuro; Suzuki, Kentaroh; Takemura, Toshihiko; Tomita, Hirofumi; Nakajima, Teruyuki

2018-03-07

Aerosols affect climate by modifying cloud properties through their role as cloud condensation nuclei or ice nuclei, called aerosol-cloud interactions. In most global climate models (GCMs), the aerosol-cloud interactions are represented by empirical parameterisations, in which the mass of cloud liquid water (LWP) is assumed to increase monotonically with increasing aerosol loading. Recent satellite observations, however, have yielded contradictory results: LWP can decrease with increasing aerosol loading. This difference implies that GCMs overestimate the aerosol effect, but the reasons for the difference are not obvious. Here, we reproduce satellite-observed LWP responses using a global simulation with explicit representations of cloud microphysics, instead of the parameterisations. Our analyses reveal that the decrease in LWP originates from the response of evaporation and condensation processes to aerosol perturbations, which are not represented in GCMs. The explicit representation of cloud microphysics in global scale modelling reduces the uncertainty of climate prediction.

Laboratory testing of a building envelope segment based on cellular concrete

NASA Astrophysics Data System (ADS)

Fořt, Jan; Pavlík, Zbyšek; Černý, Robert

2016-07-01

Hygrothermal performance of a building envelope based on cellular concrete blocks is studied in the paper. Simultaneously, the strain fields induced by the heat and moisture changes are monitored. The studied wall is exposed to the climatic load corresponding to the winter climatic conditions of the moderate year for Prague. The winter climatic exposure is chosen in order to simulate the critical conditions of the building structure from the point of view of material performance and temperature and humidity loading. The evaluation of hygrothermal performance of a researched wall is done on the basis of relative humidity and temperature profiles measured along the cross section of the cellular concrete blocks. Strain gauges are fixed on the wall surface in expected orientation of the blocks expansion. The obtained results show a good hygrothermal function of the analyzed cellular concrete wall and its insignificant strain.

Green infrastructure and urban sustainability

NASA Astrophysics Data System (ADS)

Hagishima, Aya

2018-02-01

Temperature increase in urban areas due to the urban heat island as well as the global climate change inevitably raises the peak load supply for space cooling as well as the risk of heat-related illness in hot climate. This paper provides the comprehensive review of the thermal mitigation effect of urban vegetation based on the field observations.

Weather, Climate, Web 2.0: 21st Century Students Speak Climate Science Well

ERIC Educational Resources Information Center

Sundberg, Cheryl White; Kennedy, Teresa; Odell, Michael R. L.

2013-01-01

Problem-based learning (PBL) and inquiry learning (IL) employ extensive scaffolding that results in cognitive load reduction and allows students to learn in complex domains. Hybrid teacher professional development models (PDM) using 21st century social collaboration tools embedding PBL and IL shows promise as a systemic approach for increasing…

The thermal environment of the human being on the global scale

PubMed Central

Jendritzky, Gerd; Tinz, Birger

2009-01-01

Background The close relationship between human health, performance, well-being and the thermal environment is obvious. Nevertheless, most studies of climate and climate change impacts show amazing shortcomings in the assessment of the environment. Populations living in different climates have different susceptibilities, due to socio-economic reasons, and different customary behavioural adaptations. The global distribution of risks of hazardous thermal exposure has not been analysed before. Objective To produce maps of the baseline and future bioclimate that allows a direct comparison of the differences in the vulnerability of populations to thermal stress across the world. Design The required climatological data fields are obtained from climate simulations with the global General Circulation Model ECHAM4 in T106-resolution. For the thermo-physiologically relevant assessment of these climate data a complete heat budget model of the human being, the ‘Perceived Temperature’ procedure has been applied which already comprises adaptation by clothing to a certain degree. Short-term physiological acclimatisation is considered via Health Related Assessment of the Thermal Environment. Results The global maps 1971–1980 (control run, assumed as baseline climate) show a pattern of thermal stress intensities as frequencies of heat. The heat load for people living in warm–humid climates is the highest. Climate change will lead to clear differences in health-related thermal stress between baseline climate and the future bioclimate 2041–2050 based on the ‘business-as-usual’ greenhouse gas scenario IS92a. The majority of the world's population will be faced with more frequent and more intense heat strain in spite of an assumed level of acclimatisation. Further adaptation measures are crucial in order to reduce the vulnerability of the populations. Conclusions This bioclimatology analysis provides a tool for various questions in climate and climate change impact research. Considerations of regional or local scale require climate simulations with higher resolution. As adaptation is the key term in understanding the role of climate/climate change for human health, performance and well-being, further research in this field is crucial. PMID:20052427

Suspended sediment source areas and future climate impact on soil erosion and sediment yield in a New York City water supply watershed, USA

NASA Astrophysics Data System (ADS)

Mukundan, Rajith; Pradhanang, Soni M.; Schneiderman, Elliot M.; Pierson, Donald C.; Anandhi, Aavudai; Zion, Mark S.; Matonse, Adão H.; Lounsbury, David G.; Steenhuis, Tammo S.

2013-02-01

High suspended sediment loads and the resulting turbidity can impact the use of surface waters for water supply and other designated uses. Changes in fluvial sediment loads influence material fluxes, aquatic geochemistry, water quality, channel morphology, and aquatic habitats. Therefore, quantifying spatial and temporal patterns in sediment loads is important both for understanding and predicting soil erosion and sediment transport processes as well as watershed-scale management of sediment and associated pollutants. A case study from the 891 km2 Cannonsville watershed, one of the major watersheds in the New York City water supply system is presented. The objective of this study was to apply Soil and Water Assessment Tool-Water Balance (SWAT-WB), a physically based semi-distributed model to identify suspended sediment generating source areas under current conditions and to simulate potential climate change impacts on soil erosion and suspended sediment yield in the study watershed for a set of future climate scenarios representative of the period 2081-2100. Future scenarios developed using nine global climate model (GCM) simulations indicate a sharp increase in the annual rates of soil erosion although a similar result in sediment yield at the watershed outlet was not evident. Future climate related changes in soil erosion and sediment yield appeared more significant in the winter due to a shift in the timing of snowmelt and also due to a decrease in the proportion of precipitation received as snow. Although an increase in future summer precipitation was predicted, soil erosion and sediment yield appeared to decrease owing to an increase in soil moisture deficit and a decrease in water yield due to increased evapotranspiration.

Runoff and phosphorus loads from two Iowa fields with and without applied manure, 2000-2011

USDA-ARS?s Scientific Manuscript database

Understanding the dynamics of field-edge runoff water quality and responses to changes in management practices and climate through monitoring will probably require decade-duration data sets. This study compared runoff volumes and phosphorus loads from two fields in central Iowa, where the glacial la...

Responses of streamflow and sediment load to climate change and human activity in the Upper Yellow River, China: a case of the Ten Great Gullies Basin.

PubMed

Liu, Tong; Huang, He Qing; Shao, Mingan; Yao, Wenyi; Gu, Jing; Yu, Guoan

2015-01-01

Soil erosion and land desertification are the most serious environmental problems globally. This study investigated the changes in streamflow and sediment load from 1964 to 2012 in the Ten Great Gullies area of the Upper Yellow River. Tests for gradual trends (Mann-Kendall test) and abrupt changes (Pettitt test) identify that significant declines in streamflow and sediment load occurred in 1997-1998 in two typical gullies. A comparison of climatic variability before and after the change points shows no statistically significant trends in annual precipitation and potential evapotranspiration. Human activities have been very active in the region and during 1990-2010, 146.01 and 197.62 km2 of land were converted, respectively, to forests and grassland, with corresponding increases of 87.56 and 77.05%. In addition, a large number of check dams have been built up in the upper reaches of the ten gullies. These measures were likely responsible for the significant decline in the annual streamflow and sediment load over the last 49 years.

Nutrient loads exported from managed catchments reveal emergent biogeochemical stationarity

NASA Astrophysics Data System (ADS)

Basu, Nandita B.; Destouni, Georgia; Jawitz, James W.; Thompson, Sally E.; Loukinova, Natalia V.; Darracq, Amélie; Zanardo, Stefano; Yaeger, Mary; Sivapalan, Murugesu; Rinaldo, Andrea; Rao, P. Suresh C.

2010-12-01

Complexity of heterogeneous catchments poses challenges in predicting biogeochemical responses to human alterations and stochastic hydro-climatic drivers. Human interferences and climate change may have contributed to the demise of hydrologic stationarity, but our synthesis of a large body of observational data suggests that anthropogenic impacts have also resulted in the emergence of effective biogeochemical stationarity in managed catchments. Long-term monitoring data from the Mississippi-Atchafalaya River Basin (MARB) and the Baltic Sea Drainage Basin (BSDB) reveal that inter-annual variations in loads (LT) for total-N (TN) and total-P (TP), exported from a catchment are dominantly controlled by discharge (QT) leading inevitably to temporal invariance of the annual, flow-weighted concentration, $\\overline{Cf = (LT/QT). Emergence of this consistent pattern across diverse managed catchments is attributed to the anthropogenic legacy of accumulated nutrient sources generating memory, similar to ubiquitously present sources for geogenic constituents that also exhibit a linear LT-QT relationship. These responses are characteristic of transport-limited systems. In contrast, in the absence of legacy sources in less-managed catchments, $\\overline{Cf values were highly variable and supply limited. We offer a theoretical explanation for the observed patterns at the event scale, and extend it to consider the stochastic nature of rainfall/flow patterns at annual scales. Our analysis suggests that: (1) expected inter-annual variations in LT can be robustly predicted given discharge variations arising from hydro-climatic or anthropogenic forcing, and (2) water-quality problems in receiving inland and coastal waters would persist until the accumulated storages of nutrients have been substantially depleted. The finding has notable implications on catchment management to mitigate adverse water-quality impacts, and on acceleration of global biogeochemical cycles.

Fluctuations in fluvial style in the Wasatch Formation, Piceance Basin, Colorado: Climatic, tectonic, or sediment driven

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nadon, G.C.; Lorenz, J.C.; Lafrenier, L.

1996-01-01

The Molina Member of the Wasatch Formation is a primary objective for light gas sandstone production. The G-Sandstone unit of the Molina produces an average of 200 MCFGPD. The chert-rich sandstones and conglomerates of the Molina Member, which are exposed in two subparallel belts on the western and eastern sides of the basin, are strikingly different from the remainder of the Wasatch formation. The underlying Atwell Gulch Member and overlying Shire Member are composed of floodplain mudstones with well developed paleosols and rare, lenticular channel sandstones. Both units are interpreted as anastomosed fluvial deposits. The Molina Member, which varies frommore » 32-118 m thick and in places contains clasts >0.2 m, is more difficult to interpret. Different portions of individual sections contain significant proportions of parallel laminated sandstones up to 5 m thick and several hundred meters wide. These parallel laminated sandstones are most common to the north along the western outcrop bell. They are interbedded with sandstones and conglomerates that are typical of a braided fluvial deposit. The contact between the two fluvial styles is sharp but conformable. The Molina Member therefore represents a perturbation in fluvial style from suspended-load to bedload and back to suspended-load over a restricted time interval. This may be the product of a change in climate, i.e., a change in rainfall amount or timing in the source area, source rock, e.g., the unroofing of a Jurassic eolian sandstone, or an increase in the depositional slope due to uplift. The return to a mud-dominated depositional system in the Shire Member argues for either climatic or source-rock variations as the primary control of the fluvial style.« less

Fluctuations in fluvial style in the Wasatch Formation, Piceance Basin, Colorado: Climatic, tectonic, or sediment driven?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nadon, G.C.; Lorenz, J.C.; Lafrenier, L.

1996-12-31

The Molina Member of the Wasatch Formation is a primary objective for light gas sandstone production. The G-Sandstone unit of the Molina produces an average of 200 MCFGPD. The chert-rich sandstones and conglomerates of the Molina Member, which are exposed in two subparallel belts on the western and eastern sides of the basin, are strikingly different from the remainder of the Wasatch formation. The underlying Atwell Gulch Member and overlying Shire Member are composed of floodplain mudstones with well developed paleosols and rare, lenticular channel sandstones. Both units are interpreted as anastomosed fluvial deposits. The Molina Member, which varies frommore » 32-118 m thick and in places contains clasts >0.2 m, is more difficult to interpret. Different portions of individual sections contain significant proportions of parallel laminated sandstones up to 5 m thick and several hundred meters wide. These parallel laminated sandstones are most common to the north along the western outcrop bell. They are interbedded with sandstones and conglomerates that are typical of a braided fluvial deposit. The contact between the two fluvial styles is sharp but conformable. The Molina Member therefore represents a perturbation in fluvial style from suspended-load to bedload and back to suspended-load over a restricted time interval. This may be the product of a change in climate, i.e., a change in rainfall amount or timing in the source area, source rock, e.g., the unroofing of a Jurassic eolian sandstone, or an increase in the depositional slope due to uplift. The return to a mud-dominated depositional system in the Shire Member argues for either climatic or source-rock variations as the primary control of the fluvial style.« less

Impacts of Climate Change on Regulated Streamflow, Hydrologic Extremes, Hydropower Production, and Sediment Discharge in the Skagit River Basin

USGS Publications Warehouse

Lee, Se-Yeun; Hamlet, Alan F.; Grossman, Eric E.

2016-01-01

Previous studies have shown that the impacts of climate change on the hydrologic response of the Skagit River are likely to be substantial under natural (i.e. unregulated) conditions. To assess the combined effects of changing natural flow and dam operations that determine impacts to regulated flow, a new integrated daily-time-step reservoir operations model was constructed for the Skagit River Basin. The model was used to simulate current reservoir operating policies for historical flow conditions and for projected flows for the 2040s (2030–2059) and 2080s (2070–2099). The results show that climate change is likely to cause substantial seasonal changes in both natural and regulated flow, with more flow in the winter and spring, and less in summer. Hydropower generation in the basin follows these trends, increasing (+ 19%) in the winter/ spring, and decreasing (- 29%) in the summer by the 2080s. The regulated 100-year flood is projected to increase by 23% by the 2040s and 49% by the 2080s. Peak winter sediment loading in December is projected to increase by 335% by the 2080s in response to increasing winter flows, and average annual sediment loading increases from 2.3 to 5.8 teragrams (+ 149%) per year by the 2080s. Regulated extreme low flows (7Q10) are projected to decrease by about 30% by the 2080s, but remain well above natural low flows. Both current and proposed alternative flood control operations are shown to be largely ineffective in mitigating increasing flood risks in the lower Skagit due to the distribution of flow in the basin during floods.

Data-driven nutrient analysis and reality check: Human inputs, catchment delivery and management effects

NASA Astrophysics Data System (ADS)

Destouni, G.

2017-12-01

Measures for mitigating nutrient loads to aquatic ecosystems should have observable effects, e.g, in the Baltic region after joint first periods of nutrient management actions under the Baltic Sea Action Plan (BASP; since 2007) and the EU Water Framework Directive (WFD; since 2009). Looking for such observable effects, all openly available water and nutrient monitoring data since 2003 are compiled and analyzed for Sweden as a case study. Results show that hydro-climatically driven water discharge dominates the determination of waterborne loads of both phosphorus and nitrogen. Furthermore, the nutrient loads and water discharge are all similarly well correlated with the ecosystem status classification of Swedish water bodies according to the WFD. Nutrient concentrations, which are hydro-climatically correlated and should thus reflect human effects better than loads, have changed only slightly over the study period (2003-2013) and even increased in moderate-to-bad status waters, where the WFD and BSAP jointly target nutrient decreases. These results indicate insufficient distinction and mitigation of human-driven nutrient components by the internationally harmonized applications of both the WFD and the BSAP. Aiming for better general identification of such components, nutrient data for the large transboundary catchments of the Baltic Sea and the Sava River are compared. The comparison shows cross-regional consistency in nutrient relationships to driving hydro-climatic conditions (water discharge) for nutrient loads, and socio-economic conditions (population density and farmland share) for nutrient concentrations. A data-driven screening methodology is further developed for estimating nutrient input and retention-delivery in catchments. Its first application to nested Sava River catchments identifies characteristic regional values of nutrient input per area and relative delivery, and hotspots of much larger inputs, related to urban high-population areas.

Simulated building energy demand biases resulting from the use of representative weather stations

DOE PAGES

Burleyson, Casey D.; Voisin, Nathalie; Taylor, Z. Todd; ...

2017-11-06

Numerical building models are typically forced with weather data from a limited number of “representative cities” or weather stations representing different climate regions. The use of representative weather stations reduces computational costs, but often fails to capture spatial heterogeneity in weather that may be important for simulations aimed at understanding how building stocks respond to a changing climate. Here, we quantify the potential reduction in temperature and load biases from using an increasing number of weather stations over the western U.S. Our novel approach is based on deriving temperature and load time series using incrementally more weather stations, ranging frommore » 8 to roughly 150, to evaluate the ability to capture weather patterns across different seasons. Using 8 stations across the western U.S., one from each IECC climate zone, results in an average absolute summertime temperature bias of ~4.0 °C with respect to a high-resolution gridded dataset. The mean absolute bias drops to ~1.5 °C using all available weather stations. Temperature biases of this magnitude could translate to absolute summertime mean simulated load biases as high as 13.5%. Increasing the size of the domain over which biases are calculated reduces their magnitude as positive and negative biases may cancel out. Using 8 representative weather stations can lead to a 20–40% bias of peak building loads during both summer and winter, a significant error for capacity expansion planners who may use these types of simulations. Using weather stations close to population centers reduces both mean and peak load biases. Our approach could be used by others designing aggregate building simulations to understand the sensitivity to their choice of weather stations used to drive the models.« less

Simulated building energy demand biases resulting from the use of representative weather stations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burleyson, Casey D.; Voisin, Nathalie; Taylor, Z. Todd

Numerical building models are typically forced with weather data from a limited number of “representative cities” or weather stations representing different climate regions. The use of representative weather stations reduces computational costs, but often fails to capture spatial heterogeneity in weather that may be important for simulations aimed at understanding how building stocks respond to a changing climate. Here, we quantify the potential reduction in temperature and load biases from using an increasing number of weather stations over the western U.S. Our novel approach is based on deriving temperature and load time series using incrementally more weather stations, ranging frommore » 8 to roughly 150, to evaluate the ability to capture weather patterns across different seasons. Using 8 stations across the western U.S., one from each IECC climate zone, results in an average absolute summertime temperature bias of ~4.0 °C with respect to a high-resolution gridded dataset. The mean absolute bias drops to ~1.5 °C using all available weather stations. Temperature biases of this magnitude could translate to absolute summertime mean simulated load biases as high as 13.5%. Increasing the size of the domain over which biases are calculated reduces their magnitude as positive and negative biases may cancel out. Using 8 representative weather stations can lead to a 20–40% bias of peak building loads during both summer and winter, a significant error for capacity expansion planners who may use these types of simulations. Using weather stations close to population centers reduces both mean and peak load biases. Our approach could be used by others designing aggregate building simulations to understand the sensitivity to their choice of weather stations used to drive the models.« less

The Effect of Mitigation Policy on Regional Climate Impacts on the U.S. Electric Sector

NASA Astrophysics Data System (ADS)

Cohen, S. M.; Sun, Y.; Strzepek, K.; McFarland, J.; Boehlert, B.; Fant, C.

2017-12-01

Climate change can influence the U.S. electricity sector in many ways, the nature of which can be shaped by energy and environmental policy choices. Changing temperatures affect electricity demand largely through heating and cooling needs, and temperatures also affect generation and transmission system performance. Altered precipitation patterns affect the regional and seasonal distribution of surface water runoff, which changes hydropower operation and thermal cooling water availability. The extent to which these stimuli influence U.S. power sector operation and planning will depend to some extent on whether or not proactive policies are enacted to mitigate these impacts. Mitigation policies such as CO2 emissions limits or technology restrictions can change the makeup of the electricity system while reducing the extent of climate change itself. We use the National Renewable Energy Laboratory's Regional Energy Deployment System (ReEDS), a U.S. electric sector capacity expansion model, to explore electric sector evolution through 2050 under alternative climate and policy assumptions. The model endogenously represents climate impacts on load, power system performance, cooling water availability, and hydropower, allowing internally consistent system responses to climate change along with projected technology, market, and policy conditions. We compare climate impacts across 5 global circulation models for a 8.5 W/m2 representative concentration pathway (RCP) without a climate mitigation policy and a 4.5 W/m2 RCP with climate mitigation. Climate drivers affect the capacity and generation mix at the national and regional levels, with relative growth of wind, solar, and natural gas-based technologies depending on local electricity system characteristics. These differences affect regional economic impacts, measured here as changes to electricity price and system costs. Mitigation policy reduces the economic and system impacts of climate change largely by moderating temperature-induced load but also by lessening water- and temperature-based performance constraints. Policy impacts are nuanced and region-specific, and this analysis underscores the importance of climate mitigation policy to regional electricity system planning decisions.

Incorporating Climate Change Predictions into Watershed Restoration and Protection Strategies (WRAPS) in the Upper Mississippi River Basin

NASA Astrophysics Data System (ADS)

Burke, M. P.; Foreman, C. S.

2014-12-01

Development of the Watershed Restoration and Protection Strategies (WRAPS) for the Pine and Leech Lake River Watersheds is underway in Minnesota. Project partners participating in this effort include the Minnesota Pollution Control Agency (MPCA), Crow Wing Soil and Water Conservation District (SWCD), Cass County, and other local partners. These watersheds are located in the Northern Lakes and Forest ecoregion of Minnesota and drain to the Upper Mississippi River. To support the Pine and Leech Lake River WRAPS, watershed-scale hydrologic and water-quality models were developed with Hydrological Simulation Program-FORTRAN (HSPF). The HSPF model applications simulate hydrology (discharge, stage), as well as a number of water quality constituents (sediment, temperature, organic and inorganic nitrogen, total ammonia, organic and inorganic phosphorus, dissolved oxygen and biochemical oxygen demand, and algae) continuously for the period 1995-2009 and provide predictions at points of interest within the watersheds, such as observation gages, management boundaries, compliance points, and impaired water body endpoints. The model applications were used to evaluate phosphorus loads to surface waters under resource management scenarios, which were based on water quality threats that were identified at stakeholder meetings. Simulations of land use changes including conversion of forests to agriculture, shoreline development, and full build-out of cities show a watershed-wide phosphorus increases of up to 80%. The retention of 1.1 inches of runoff from impervious surfaces was not enough to mitigate the projected phosphorus load increases. Changes in precipitation projected by climate change models led to a 20% increase in annual watershed phosphorus loads. The scenario results will inform the implementation strategies selected for the WRAPS.

Association between meteorological factors and bacillary dysentery incidence in Chaoyang city, China: an ecological study

PubMed Central

Zhao, Yang; Zhu, Yaxin; Zhu, Zhiwei; Qu, Bo

2016-01-01

Objectives To quantify the relationship between meteorological factors and bacillary dysentery incidence. Design Ecological study. Setting We collected bacillary dysentery incidences and meteorological data of Chaoyang city from the year 1981 to 2010. The climate in this city was a typical northern temperate continental monsoon. All meteorological factors in this study were divided into 4 latent factors: temperature, humidity, sunshine and airflow. Structural equation modelling was used to analyse the relationship between meteorological factors and the incidence of bacillary dysentery. Material Incidences of bacillary dysentery were obtained from the Center for Disease Control and Prevention of Chaoyang city, and meteorological data were collected from the Bureau of Meteorology in Chaoyang city. Primary outcome measures The indexes including χ2, root mean square error of approximation (RMSEA), comparative fit index (CFI), standardised root mean square residual (SRMR) and goodness-of-fit index (GFI) were used to evaluate the goodness-of-fit of the theoretical model to the data. The factor loads were used to explore quantitative relationship between bacillary dysentery incidences and meteorological factors. Results The goodness-of-fit results of the model showing that RMSEA=0.08, GFI=0.84, CFI=0.88, SRMR=0.06 and the χ2 value is 231.95 (p=0.0) with 15 degrees of freedom. Temperature and humidity factors had positive correlations with incidence of bacillary dysentery, with the factor load of 0.59 and 0.78, respectively. Sunshine had a negative correlation with bacillary dysentery incidence, with a factor load of −0.15. Conclusions Humidity and temperature should be given greater consideration in bacillary dysentery prevention measures for northern temperate continental monsoon climates, such as that of Chaoyang. PMID:27940632

Influence of climate change, tidal mixing, and watershed urbanization on historical water quality in Newport Bay, a saltwater wetland and tidal embayment in southern California.

PubMed

Pednekar, Abhishek M; Grant, Stanley B; Jeong, Youngsul; Poon, Ying; Oancea, Carmen

2005-12-01

Historical coliform measurements (n = 67,269; 32 years) in Newport Bay, a regionally important saltwater wetland and tidal embayment in southern California, have been compiled and analyzed. Coliform concentrations in Newport Bay decrease along an inland-to-ocean gradient, consistent with the hypothesis that this tidal embayment attenuates fecal pollution from inland sources. Nearly 70% of the variability in the coliform record can be attributed to seasonal and interannual variability in local rainfall, implying that stormwater runoff from the surrounding watershed is a primary source of coliform in Newport Bay. The storm loading rate of coliform from the San Diego Creek watershed--the largest watershed draining into Newport Bay--appears to be unaffected by the dramatic shift away from agricultural land-use that occurred in the watershed over the study period. Further, the peak loading of coliform during storms is larger than can be reasonably attributed to sources of human sewage, suggesting that nonhuman fecal pollution and/or bacterial regrowth contribute to the coliform load. Summer time measurements of coliform exhibit interannual trends, but these trends are site specific, apparently due to within-Bay variability in land-use, inputs of dry-weather runoff, and tidal mixing rates. Overall, these results suggest that efforts to improve water quality in Newport Bay will likely have greater efficacy during dry weather summer periods. Water quality during winter storms, on the other hand, appears to be dominated by factors outside of local management control; namely, virtually unlimited nonhuman sources of coliform in the watershed and global climate patterns, such as the El Nino Southern Oscillation, that modulate rainfall and stormwater runoff in southern California.

Perennially ice-covered Lake Hoare, Antarctica: physical environment, biology and sedimentation

NASA Technical Reports Server (NTRS)

Wharton, R. A. Jr; Simmons, G. M. Jr; McKay, C. P.; Wharton RA, J. r. (Principal Investigator)

1989-01-01

Lake Hoare (77 degrees 38' S, 162 degrees 53' E) is a perennially ice-covered lake at the eastern end of Taylor Valley in southern Victoria Land, Antarctica. The environment of this lake is controlled by the relatively thick ice cover (3-5 m) which eliminates wind generated currents, restricts gas exchange and sediment deposition, and reduces light penetration. The ice cover is in turn largely controlled by the extreme seasonality of Antarctica and local climate. Lake Hoare and other dry valley lakes may be sensitive indicators of short term (< 100 yr) climatic and/or anthropogenic changes in the dry valleys since the onset of intensive exploration over 30 years ago. The time constants for turnover of the water column and lake ice are 50 and 10 years, respectively. The turnover time for atmospheric gases in the lake is 30-60 years. Therefore, the lake environment responds to changes on a 10-100 year timescale. Because the ice cover has a controlling influence on the lake (e.g. light penetration, gas content of water, and sediment deposition), it is probable that small changes in ice ablation, sediment loading on the ice cover, or glacial meltwater (or groundwater) inflow will affect ice cover dynamics and will have a major impact on the lake environment and biota.

Enhanced water use efficiency in global terrestrial ecosystems under increasing aerosol loadings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lu, Xiaoliang; Chen, Min; Liu, Yaling

Aerosols play a crucial role in the climate system, affecting incoming radiation and cloud formation. Based on a modelling framework that couples ecosystem processes with the atmospheric transfer of radiation, we analyze the effect of aerosols on surface incoming radiation, gross primary productivity (GPP), water losses from ecosystems through evapotranspiration (ET) and ecosystem water use efficiency (WUE, defined as GPP/ET) for 2003–2010 and validate them at global FLUXNET sites. The total diffuse radiation increases under relatively low or intermediate aerosol loadings, but decreases under more polluted conditions. We find that aerosol-induced changes in GPP depend on leaf area index, aerosolmore » loading and cloudiness. Specifically, low and moderate aerosol loadings cause increases in GPP for all plant types, while heavy aerosol loadings result in enhancement (decrease) in GPP for dense (sparse) vegetation. On the other hand, ET is mainly negatively affected by aerosol loadings due to the reduction in total incoming radiation. Finally, WUE shows a consistent rise in all plant types under increasing aerosol loadings. Overall, the simulated daily WUE compares well with observations at 43 eddy-covariance tower sites (R 2=0.84 and RMSE=0.01gC (kg H 2O) -1) with better performance at forest sites. In addition to the increasing portions of diffuse light, the rise in WUE is also favored by the reduction in radiation- and heat-stress caused by the aerosols, especially for wet and hot climates.« less

On the dust load and rainfall relationship in South Asia: an analysis from CMIP5

NASA Astrophysics Data System (ADS)

Singh, Charu; Ganguly, Dilip; Dash, S. K.

2018-01-01

This study is aimed at examining the consistency of the relationship between load of dust and rainfall simulated by different climate models and its implication for the Indian summer monsoon system. Monthly mean outputs of 12 climate models, obtained from the archive of the Coupled Model Intercomparison Project phase 5 (CMIP5) for the period 1951-2004, are analyzed to investigate the relationship between dust and rainfall. Comparative analysis of the model simulated precipitation with the India Meteorological Department (IMD) gridded rainfall, CRU TS3.21 and GPCP version 2.2 data sets show significant differences between the spatial patterns of JJAS rainfall as well as annual cycle of rainfall simulated by various models and observations. Similarly, significant inter-model differences are also noted in the simulation of load of dust, nevertheless it is further noted that most of the CMIP5 models are able to capture the major dust sources across the study region. Although the scatter plot analysis and the lead-lag pattern correlation between the dust load and the rainfall show strong relationship between the dust load over distant sources and the rainfall in the South Asian region in individual models, the temporal scale of this association indicates large differences amongst the models. Our results caution that it would be pre-mature to draw any robust conclusions on the time scale of the relationship between dust and the rainfall in the South Asian region based on either CMIP5 results or limited number of previous studies. Hence, we would like to emphasize upon the fact that any conclusions drawn on the relationship between the dust load and the South Asian rainfall using model simulation is highly dependent on the degree of complexity incorporated in those models such as the representation of aerosol life cycle, their interaction with clouds, precipitation and other components of the climate system.

An overview of historical channel adjustment and selected hydraulic values in the Lower Sabine and Lower Brazos River Basins, Texas and Louisiana

USGS Publications Warehouse

Heitmuller, Franklin T.; Greene, Lauren E.; John D. Gordon, John D.

2010-01-01

The Sabine and Brazos are alluvial rivers; alluvial rivers are dynamic systems that adjust their geometry in response to changes in streamflow (discharge) and sediment load. In fluvial geomorphology, the term 'channel adjustment' refers to river channel changes in three geometric dimensions: (1) channel slope (profile); (2) the outline or shape, such as meandering or braided, projected on a horizontal plane (planform); and (3) cross-sectional form (shape). The primary objective of the study was to investigate how the channel morphology of these rivers has changed in response to reservoirs and other anthropogenic disturbances that have altered streamflow and sediment load. The results of this study are expected to aid ecological assessments in the lower Sabine River and lower Brazos River Basins for the Texas Instream Flow Program. Starting in the 1920s, several dams have been constructed on the Sabine and Brazos Rivers and their tributaries, and numerous bridges have been built and sometimes replaced multiple times, which have changed the natural flow regime and reduced or altered sediment loads downstream. Changes in channel geometry over time can reduce channel conveyance and thus streamflow, which can have adverse ecological effects. Channel attributes including cross-section form, channel slope, and planform change were evaluated to learn how each river's morphology changed over many years in response to natural and anthropogenic disturbances. Climate has large influence on the hydrologic regimes of the lower Sabine and lower Brazos River Basins. Equally important as climate in controlling the hydrologic regime of the two river systems are numerous reservoirs that regulate downstream flow releases. The hydrologic regimes of the two rivers and their tributaries reflect the combined influences of climate, flow regulation, and drainage area. Historical and contemporary cross-sectional channel geometries at 15 streamflow-gaging stations in the lower Sabine and lower Brazos River Basins were evaluated. An in-depth discussion of results from streamflow-gaging station 08028500 Sabine River near Bon Weir, Tex., is featured here as an example of the analyses that were done at each station.

University students' cognitive performance under temperature cycles induced by direct load control events.

PubMed

Zhang, F; de Dear, R

2017-01-01

As one of the most common strategies for managing peak electricity demand, direct load control (DLC) of air-conditioners involves cycling the compressors on and off at predetermined intervals. In university lecture theaters, the implementation of DLC induces temperature cycles which might compromise university students' learning performance. In these experiments, university students' learning performance, represented by four cognitive skills of memory, concentration, reasoning, and planning, was closely monitored under DLC-induced temperature cycles and control conditions simulated in a climate chamber. In Experiment 1 with a cooling set point temperature of 22°C, subjects' cognitive performance was relatively stable or even slightly promoted by the mild heat intensity and short heat exposure resulting from temperature cycles; in Experiment 2 with a cooling set point of 24°C, subjects' reasoning and planning performance observed a trend of decline at the higher heat intensity and longer heat exposure. Results confirm that simpler cognitive tasks are less susceptible to temperature effects than more complex tasks; the effect of thermal variations on cognitive performance follows an extended-U relationship with performance being relatively stable across a range of temperatures. DLC appears to be feasible in university lecture theaters if DLC algorithms are implemented judiciously. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Aridity of Central Asia through the Holocene

NASA Astrophysics Data System (ADS)

Aizen, E. M.; Aizen, V. B.; Mayewski, P. A.; Zhou, H.; Rodda, C.; Joswiak, D.; Takeuchi, N.; Fujita, K.; Kurbatov, A.; Grigholm, B. O.

2017-12-01

The dynamics of aridity in Central Asia for over the past 12,000 years has been analyzed using deep ice core records recovered from the Siberian Altai, Tien Shan and Pamir glaciers. An analysis of aridity in the 20-21 centuries based on the long-term meteorological observations complements the paleo- climate reconstruction. The goal of our research is to examine an aridity (at low and high temperatures) in Central Asia as a complex of characteristics including air temperature-precipitation relationship (Koppen, 1918, Geiger, 1961, Mezencev, 1973), intensity of dust loading and biomass burning. The stable isotope ratio, soluble ionic and insoluble particulate geochemical components and oxalate preserved in ice were considered in relation to climatic and environmental changes; and to determine the main aerosol sources using ground- and upper-level meteorological data. Multivariate statistical methods were employed for examination of the main geo-chemical components responsible for the preserved aridity variability. Insoluble particle concentrations preserved in the ice core were affected mainly by precipitation regimes and wind speed. Concentration of all size particles was found to be negatively correlated with monthly temperatures indicating low temperatures during the dry particle deposition. Two abrupt depletions in stable isotope records, i.e., Younger Dryas and Centurial Sever Drought (CSD), occurred during cold, dry, windy periods of intensified dust storms in large desert areas. When climate became colder and drier, the Central Asian deserts extended, wind speeds increased loading mineral dust to atmosphere, which formed inversion while the convection processes and precipitation occurrence were limited. Warmer and wetter conditions are associated with less dust loading that occurred during the Holocene climate optimum, medieval warm and modern warm periods. The sudden climate transitions are accompanied by the most intensifying mineral dust loading. From the middle of 20th century, the potassium and nitrate ion concentrations significantly increased and reaches almost the same level as it was at the beginning of Holocene and before CSD that was caused by extended forest fires under air temperature growth. Interval between intensive biomass burning decreased during the 20th century.

Characterizing Flow and Suspended Sediment Trends in the Sacramento River Basin, CA Using Hydrologic Simulation Program - FORTRAN (HSPF)

NASA Astrophysics Data System (ADS)

Stern, M. A.; Flint, L. E.; Flint, A. L.; Wright, S. A.; Minear, J. T.

2014-12-01

A watershed model of the Sacramento River Basin, CA was developed to simulate streamflow and suspended sediment transport to the San Francisco Bay Delta (SFBD) for fifty years (1958-2008) using the Hydrological Simulation Program - FORTRAN (HSPF). To compensate for the large model domain and sparse data, rigorous meteorological development and characterization of hydraulic geometry were employed to spatially distribute climate and hydrologic processes in unmeasured locations. Parameterization techniques sought to include known spatial information for tributaries such as soil information and slope, and then parameters were scaled up or down during calibration to retain the spatial characteristics of the land surface in un-gaged areas. Accuracy was assessed by comparing model calibration to measured streamflow. Calibration and validation of the Sacramento River ranged from "good" to "very good" performance based upon a "goodness-of-fit" statistical guideline. Model calibration to measured sediment loads were underestimated on average by 39% for the Sacramento River, and model calibration to suspended sediment concentrations were underestimated on average by 22% for the Sacramento River. Sediment loads showed a slight decreasing trend from 1958-2008 and was significant (p < 0.0025) in the lower 50% of stream flows. Hypothetical climate change scenarios were developed using the Climate Assessment Tool (CAT). Several wet and dry scenarios coupled with temperature increases were imposed on the historical base conditions to evaluate sensitivity of streamflow and sediment on potential changes in climate. Wet scenarios showed an increase of 9.7 - 17.5% in streamflow, a 7.6 - 17.5% increase in runoff, and a 30 - 93% increase in sediment loads. The dry scenarios showed a roughly 5% decrease in flow and runoff, and a 16 - 18% decrease in sediment loads. The base hydrology was most sensitive to a temperature increase of 1.5 degrees Celsius and an increase in storm intensity and frequency. The complete calibrated HSPF model will use future climate scenarios to make projections of potential hydrologic and sediment trends to the SFBD from 2000-2100.

Multi-load Groups Coordinated Load Control Strategy Considering Power Network Constraints

NASA Astrophysics Data System (ADS)

Liu, Meng; Zhao, Binchao; Wang, Jun; Zhang, Guohui; Wang, Xin

2017-05-01

Loads with energy storage property can actively participate in power balance for power systems, this paper takes air conditioner as a controllable load example, proposing a multi-load groups coordinated load control strategy considering power network constraints. Firstly, two load control modes considering recovery of load diversity are designed, blocking power oscillation of aggregated air conditioners. As the same time, air conditioner temperature setpoint recovery control strategy is presented to avoid power recovery peak. Considering inherent characteristics of two load control modes, an coordinated load control mode is designed by combining the both. Basing on this, a multi-load groups coordinated load control strategy is proposed. During the implementing of load control, power network constraints should be satisfied. An indice which can reflect the security of power system operating is defined. By minimizing its value through optimization, the change of air conditioning loads’ aggregated power on each load bus can be calculated. Simulations are conducted on an air conditioners group and New England 10-generator 39-bus system, verifying the effectiveness of the proposed multi-load groups coordinated load control strategy considering power network constraints.

Probabilistic modeling of the indoor climates of residential buildings using EnergyPlus

DOE PAGES

Buechler, Elizabeth D.; Pallin, Simon B.; Boudreaux, Philip R.; ...

2017-04-25

The indoor air temperature and relative humidity in residential buildings significantly affect material moisture durability, HVAC system performance, and occupant comfort. Therefore, indoor climate data is generally required to define boundary conditions in numerical models that evaluate envelope durability and equipment performance. However, indoor climate data obtained from field studies is influenced by weather, occupant behavior and internal loads, and is generally unrepresentative of the residential building stock. Likewise, whole-building simulation models typically neglect stochastic variables and yield deterministic results that are applicable to only a single home in a specific climate. The

Environmental and economic risks assessment under climate changes for three land uses scenarios analysis across Teshio watershed, northernmost of Japan.

PubMed

Fan, Min; Shibata, Hideaki; Chen, Li

2017-12-01

Land use and climate changes affect on the economy and environment with different patterns and magnitudes in the watershed. This study used risk analysis model stochastic efficiency with respect to a function (SERF) to evaluate economic and environmental risks caused by four climate change scenarios (baseline, small-, mid- and large changes) and three land uses (paddy dominated, paddy-farmland mixture and farmland dominated for agriculture) in Teshio watershed in northern Hokkaido, Japan. Under the baseline climate conditions, the lower ranking of economic income of crop yield and higher ranking of pollutant load from agricultural land were both predicted in paddy dominated for agriculture, suggesting that the paddy dominated system caused higher risks of economic and environmental variables compared to other two land uses. Increase of temperature and precipitation increased crop yields under all three climate changes which resulted in increase of the ranking of economic income, indicating that those climate changes could reduce economic risk. The increased temperature and precipitation also accelerated mineralization of organic nutrient and nutrient leaching to river course of Teshio which resulted in increase of the ranking of pollutant load, suggesting that those climate changes could lead to more environmental risk. The rankings of economic income in mid- and large changes of climate were lower than that in small change of climate under paddy-farmland mixture and farmland dominated systems due to decrease of crop yield, suggesting that climate change led to more economic risk. In summary, the results suggested that increase in temperature and precipitation caused higher risks of both economic and environmental perspectives, and the impacts was higher than those of land use changes in the studied watershed. Those findings would help producers and watershed managers to measure the tradeoffs between environmental protection and agricultural economic development for making decision under land use and climate changes. Copyright © 2017 Elsevier B.V. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jain, Atul K.

The overall objectives of this DOE funded project is to combine scientific and computational challenges in climate modeling by expanding our understanding of the biogeophysical-biogeochemical processes and their interactions in the northern high latitudes (NHLs) using an earth system modeling (ESM) approach, and by adopting an adaptive parallel runtime system in an ESM to achieve efficient and scalable climate simulations through improved load balancing algorithms.

How climatic conditions, site, and soil characteristics affect tree growth and critical loads of nitrogen for northeastern tree species

Treesearch

Molly J. Robin-Abbott; Linda H. Pardo

2017-01-01

Forest health is affected by multiple factors, including topography, climate, and soil characteristics, as well as pests, pathogens, competitive interactions, and anthropogenic deposition. Species within a stand may respond differently to site factors depending on their physiological requirements for growth, survival, and regeneration. We determined optimal ranges of...

Wildfire risk and home purchase decisions.

Treesearch

Patricia Champ; Geoffrey Donovan; Christopher Barth

2008-01-01

In the last 20 years, wildfire damages and the costs of wildfire suppression have risen dramatically. This trend has been attributed to three main factors: climate change, increased fuel loads from a century of wildfire suppression, and increased housing development in fire-prone areas., There is little that fire managers can do about climate change, and current fuel...

Load controller and method to enhance effective capacity of a photovoltaic power supply using a dynamically determined expected peak loading

DOEpatents

Perez, Richard

2005-05-03

A load controller and method are provided for maximizing effective capacity of a non-controllable, renewable power supply coupled to a variable electrical load also coupled to a conventional power grid. Effective capacity is enhanced by monitoring power output of the renewable supply and loading, and comparing the loading against the power output and a load adjustment threshold determined from an expected peak loading. A value for a load adjustment parameter is calculated by subtracting the renewable supply output and the load adjustment parameter from the current load. This value is then employed to control the variable load in an amount proportional to the value of the load control parameter when the parameter is within a predefined range. By so controlling the load, the effective capacity of the non-controllable, renewable power supply is increased without any attempt at operational feedback control of the renewable supply.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Buechler, Elizabeth D.; Pallin, Simon B.; Boudreaux, Philip R.

The indoor air temperature and relative humidity in residential buildings significantly affect material moisture durability, HVAC system performance, and occupant comfort. Therefore, indoor climate data is generally required to define boundary conditions in numerical models that evaluate envelope durability and equipment performance. However, indoor climate data obtained from field studies is influenced by weather, occupant behavior and internal loads, and is generally unrepresentative of the residential building stock. Likewise, whole-building simulation models typically neglect stochastic variables and yield deterministic results that are applicable to only a single home in a specific climate. The

Vineyard floor management and cluster thinning inconsistently affect ‘Pinot noir’ crop load, berry composition, and wine quality

USDA-ARS?s Scientific Manuscript database

A 3-year field study was developed to determine relationships between crop load metrics and berry composition for ‘Pinot noir’ in a cool-climate through the manipulation of vegetative growth and fruit yield using competitive cover cropping and cluster thinning, respectively. To alter vine vigor, per...

The importance of considering shifts in seasonal changes in discharges when prediciting future phosphorus loads in streams

USDA-ARS?s Scientific Manuscript database

In this work, we hypothesize that phosphorus (P) concentrations in streams vary seasonally and with streamflow and that it is important to incorporate this variation when predicting changes in P loading associated with climate change. Our study area includes 14 watersheds with a range of land uses t...

44. HISTORIC VIEW LOOKING WEST AT THE TEST STAND AND ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

44. HISTORIC VIEW LOOKING WEST AT THE TEST STAND AND ROCKET BEING PREPARED FOR TESTING. NOTE THE LOAD CELL APPARATUS ABOVE THE ROCKET AND THE EQUIPMENT PLATFORM TO THE LEFT OF THE LOAD CELL HAVE BEEN ENCLOSED FOR PROTECTION FROM THE CLIMATE. - Marshall Space Flight Center, Redstone Rocket (Missile) Test Stand, Dodd Road, Huntsville, Madison County, AL

Simulator with integrated HW and SW for prediction of thermal comfort to provide feedback to the climate control system

NASA Astrophysics Data System (ADS)

Pokorný, Jan; Kopečková, Barbora; Fišer, Jan; JÍcha, Miroslav

2018-06-01

The aim of the paper is to assemble a simulator for evaluation of thermal comfort in car cabins in order to give a feedback to the HVAC (heating, ventilation and air conditioning) system. The HW (hardware) part of simulator is formed by thermal manikin Newton and RH (relative humidity), velocity and temperature probes. The SW (software) part consists of the Thermal Comfort Analyser (using ISO 14505-2) and Virtual Testing Stand of Car Cabin defining the heat loads of car cabin. Simulator can provide recommendation for the climate control how to improve thermal comfort in cabin by distribution and directing of air flow, and also by amount of ventilation power to keep optimal temperature inside a cabin. The methods of evaluation of thermal comfort were verified by tests with 10 test subjects for summer (summer clothing, ambient air temperature 30 °C, HVAC setup: +24 °C auto) and winter conditions (winter clothing, ambient air temperature -5 °C, HVAC setup: +18 °C auto). The tests confirmed the validity of the thermal comfort evaluation using the thermal manikin and ISO 14505-2.

An experimental study of summertime coastal fog and its inland penetration in Northern California

NASA Astrophysics Data System (ADS)

Lucena Kreppel Paes, P.; Torres, P.; Faloona, I. C.; Torregrosa, A.; Gultepe, I.

2012-12-01

The occurrence and continental inundation of marine stratocumulus and fog along the California Coast during summer has been linked to many environmental concerns including redwood ecosystem vitality, air traffic control, power grid load balancing, and radiatve climate forcing. An exploratory study was instigated this past summer at the Bodega Marine Laboratory and Pepperwood Preserve, a large nature reserve located 40 km inland in Sonoma County, in order to investigate fog formation, persistence, and penetration through the orographic gap in the Pacific coastal mountain range. Analysis of the synoptic patterns and in-situ meteorological observations, including visibility and boundary layer depth, are presented with the aim of improving fog forecasts and elucidating the principal physical parameters that control summertime fog formation and dissipation along the Northern California Coast.

Load controller and method to enhance effective capacity of a photovotaic power supply using a dynamically determined expected peak loading

DOEpatents

Perez, Richard

2003-04-01

A load controller and method are provided for maximizing effective capacity of a non-controllable, renewable power supply coupled to a variable electrical load also coupled to a conventional power grid. Effective capacity is enhanced by monitoring power output of the renewable supply and loading, and comparing the loading against the power output and a load adjustment threshold determined from an expected peak loading. A value for a load adjustment parameter is calculated by subtracting the renewable supply output and the load adjustment parameter from the current load. This value is then employed to control the variable load in an amount proportional to the value of the load control parameter when the parameter is within a predefined range. By so controlling the load, the effective capacity of the non-controllable, renewable power supply is increased without any attempt at operational feedback control of the renewable supply. The expected peak loading of the variable load can be dynamically determined within a defined time interval with reference to variations in the variable load.

Energy demand hourly simulations and energy saving strategies in greenhouses for the Mediterranean climate

NASA Astrophysics Data System (ADS)

Priarone, A.; Fossa, M.; Paietta, E.; Rolando, D.

2017-01-01

This research has been devoted to the selection of the most favourable plant solutions for ventilation, heating and cooling, thermo-hygrometric control of a greenhouse, in the framework of the energy saving and the environmental protection. The identified plant solutions include shading of glazing surfaces, natural ventilation by means of controlled opening windows, forced convection of external air and forced convection of air treated by the HVAC system for both heating and cooling. The selected solution combines HVAC system to a Ground Coupled Heat Pump (GCHP), which is an innovative renewable technology applied to greenhouse buildings. The energy demand and thermal loads of the greenhouse to fulfil the requested internal design conditions have been evaluated through an hourly numerical simulation, using the Energy Plus (E-plus) software. The overall heat balance of the greenhouse also includes the latent heat exchange due to crop evapotranspiration, accounted through an original iterative calculation procedure that combines the E-plus dynamic simulations and the FAO Penman-Monteith method. The obtained hourly thermal loads have been used to size the borehole field for the geothermal heat pump by using a dedicated GCHP hourly simulation tool.

Tropical Cyclones as a Driver of Global Sediment Flux

NASA Astrophysics Data System (ADS)

Leyland, J.; Darby, S. E.; Cohen, S.

2017-12-01

The world's rivers deliver 19 billion tonnes of sediment to the coastal zone annually. The sediment supplied to the coastal zone is of significant importance for a variety of reasons, for example in acting as a vector for nutrients as well as in supplying sediment to coastal landforms such as deltas and beaches that can buffer those landforms from erosion and flooding. A greater understanding of the factors governing sediment flux to the oceans is therefore a key research gap. The non-linear relationship between river discharge and sediment flux implies that the global sediment flux may be disproportionately driven by large floods. Indeed, in our recent empirical research we have demonstrated that changes in the track locations, frequency and intensity of tropical storms in recent decades exert a significant control on the sediment flux emanating from the Mekong River. Since other large rivers potentially affected by tropical storms are known to make a significant contribution to the global sediment flux, this raises the question of the extent to which such storms play a significant role in controlling sediment loads at the global scale. In this paper we address that question by employing a global hydrological model (WBMsed) in order to predict runoff and sediment load forced by recent historical climate scenarios `with' and `without' tropical cyclones. We compare the two scenarios to (i) make the first estimate of the global contribution of sediment load forced by tropical storms; (ii) evaluate how that contribution has varied in recent decades and to (iii) explore variations in tropical-storm driven sediment loads in selected major river basins that are significantly affected by such storms.

Get In and Get Out: Assessing Stream Sediment Loading from Short Duration Forest Harvest Operations and Rapid Haul Road Decommissioning.

NASA Astrophysics Data System (ADS)

Corrigan, A.; Silins, U.; Stone, M.

2016-12-01

Best management practices (BMPs) and associated erosion control measures for mitigating sediment impacts from forestry roads and road-stream crossings are well documented. While rapid road decommissioning after forestry operations may serve to limit broader impacts on sediment production in high value headwater streams, few studies have evaluated the combined effects of accelerated harvest operations and rapid retirement of logging roads and road-stream crossings on stream sediment. The objectives of this study were to evaluate the initial impacts of these strategies on fine sediment loading and fate during a short duration harvesting operation in 3 headwater sub-catchments in the southwestern Rocky Mountains of Alberta, Canada. A multi-pronged sampling approach (ISCOs, event focused grab sampling, continuous wash load sampling, and stream bed sediment intrusion measurements) was used to measure sediment loading and deposition in streambeds upstream and downstream of road-stream bridge crossings during harvest operations (2015) and after road and bridge crossing retirement (2016). Sediment production from forestry roads was generally much lower than has been reported from other studies in similar settings. Average total suspended solids (TSS) downstream of the bridge crossings were actually lower (-3.28 g/L; -0.704 g/L) than upstream of two bridge crossings while in-stream sediment sources contributed to elevated sediment downstream of a third road-stream crossing. Minimal in stream sediment impacts from forest harvest and road-stream crossings was likely a reflection of combined factors including a) employment of erosion control BMPs to roads and bridge crossings, b) rapid decommissioning of roads and crossings to limit exposure of linear land disturbance features, and c) drier El Niño climatic conditions during the study.

Interannual Variability of Dust and Ice in the Mars Atmosphere: Comparison of MRO Mars Climate Sounder Retrievals with MGS-TES Limb Sounding Retrievals

NASA Technical Reports Server (NTRS)

Shirley, J. H.; McConnochie, T. H.; Kleinbohl, A.; Schofield, J. T.; Kass, D.; Heavens, N. G.; Benson, J.; McCleese, D. J.

2011-01-01

Dust and ice play important roles in Martian atmospheric dynamics on all time scales. Dust loading in particular exerts an important control on atmospheric temperatures and thereby on the strength of the atmospheric circulation in any given year. We present the first comparisons of MGS-TES aerosol opacity profiles with MRO-MCS aerosol opacity profiles. While the differences in vertical resolution are significant (a factor of 2), we find good agreement at particular seasons between nightside zonal average dust opacity profiles from the two instruments. Derived water ice opacities are likewise similar but show greater variability.

CASA Forest Cover Change Data Sets

NASA Technical Reports Server (NTRS)

Potter, Christopher S.

2012-01-01

Deforestation and forest fires are global land cover changes that can be caused by both natural and human factors. Although monitoring forest fires in near-real time is critical for operational wildfire management, mapping historical wildfires in a spatially explicit fashion is also important for a number of reasons, including climate change studies (e.g., examining the relationship between rising temperatures and frequency of fires), fuel load management (e.g., deciding when and where to conduct controlled burns), and carbon cycle studies (e.g., quantifying how much CO2 is emitted by fires and for emissions reduction efforts under the United Nations programs for Reducing Emissions from Deforestation and Degradation -- REDD).

CARDS - comprehensive aerological reference data set. Station history, Version 2.1

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

1994-03-01

The possibility of anthropogenic climate change has reached the attention of Government officials and researchers. However, one cannot study climate change without climate data. The CARDS project will produce high-quality upper-air data for the research community and for policy-makers. The authors intend to produce a dataset which is: easy to use, as complete as possible, as free of random errors as possible. They will also attempt to identify biases and remove them whenever possible. In this report, they relate progress toward their goal. They created a robust new format for archiving upper-air data, and designed a relational database structure tomore » hold them. The authors have converted 13 datasets to the new format and have archived over 10,000,000 individual soundings from 10 separate data sources. They produce and archive a metadata summary of each sounding they load. They have researched station histories, and have built a preliminary upper-air station history database. They have converted station-sorted data from their primary database into synoptic-sorted data in a parallel database. They have tested and will soon implement an advanced quality-control procedure, capable of detecting and often repairing errors in geopotential height, temperature, humidity, and wind. This unique quality-control method uses simultaneous vertical, horizontal, and temporal checks of several meteorological variables. It can detect errors other methods cannot. This report contains the station histories for the CARDS data set.« less

Relevance of Regional Hydro-Climatic Projection Data for Hydrodynamics and Water Quality Modelling of the Baltic Sea

NASA Astrophysics Data System (ADS)

Goldenberg, R.; Vigouroux, G.; Chen, Y.; Bring, A.; Kalantari, Z.; Prieto, C.; Destouni, G.

2017-12-01

The Baltic Sea, located in Northern Europe, is one of the world's largest body of brackish water, enclosed and surrounded by nine different countries. The magnitude of climate change may be particularly large in northern regions, and identifying its impacts on vulnerable inland waters and their runoff and nutrient loading to the Baltic Sea is an important and complex task. Exploration of such hydro-climatic impacts is needed to understand potential future changes in physical, ecological and water quality conditions in the regional coastal and marine waters. In this study, we investigate hydro-climatic changes and impacts on the Baltic Sea by synthesizing multi-model climate projection data from the CORDEX regional downscaling initiative (EURO- and Arctic- CORDEX domains, http://www.cordex.org/). We identify key hydro-climatic variable outputs of these models and assess model performance with regard to their projected temporal and spatial change behavior and impacts on different scales and coastal-marine parts, up to the whole Baltic Sea. Model spreading, robustness and impact implications for the Baltic Sea system are investigated for and through further use in simulations of coastal-marine hydrodynamics and water quality based on these key output variables and their change projections. Climate model robustness in this context is assessed by inter-model spreading analysis and observation data comparisons, while projected change implications are assessed by forcing of linked hydrodynamic and water quality modeling of the Baltic Sea based on relevant hydro-climatic outputs for inland water runoff and waterborne nutrient loading to the Baltic sea, as well as for conditions in the sea itself. This focused synthesis and analysis of hydro-climatically relevant output data of regional climate models facilitates assessment of reliability and uncertainty in projections of driver-impact changes of key importance for Baltic Sea physical, water quality and ecological conditions and their future evolution.

1996-2007 Interannual Spatio-Temporal Variability in Snowmelt in Two Montane Watersheds

NASA Astrophysics Data System (ADS)

Jepsen, S. M.; Molotch, N. P.; Rittger, K. E.

2009-12-01

Snowmelt is a primary water source for ecosystems within, and urban/agricultural centers near, mountain regions. Stream chemistry from montane catchments is controlled by the flowpaths of water from snowmelt and the timing and duration of snow coverage. A process level understanding of the variability in these processes requires an understanding of the effect of changing climate and anthropogenic loading on spatio-temporal snowmelt patterns. With this as our objective, we are applying a snow reconstruction model to two well-studied montane watersheds, Tokopah Basin (TOK), California and Green Lakes Valley (GLV), Colorado, to examine interannual variability in the timing and location of snowmelt in response to variable climate conditions during the period from 1996 to 2007. The reconstruction model back solves for snowmelt by combining surface energy fluxes, inferred from meteorological data, with sequences of melt season snow images derived from satellite data (i.e., snowmelt depletion curves). Preliminary model results for 2002 were tested against measured snow water equivalent (SWE) and hydrograph data for the two watersheds. The computed maximum SWE averaged over TOK and GLV were 94 cm (~+17% error) and 50.2 cm (~+1% error), respectively. We present an analysis of interannual variability in these errors, in addition to reconstructed snowmelt maps over different land cover types under changing climate conditions between 1996-2007, focusing on the variability with interannual variation in climate.

Role of aerosols on the Indian Summer Monsoon variability, as simulated by state-of-the-art global climate models

NASA Astrophysics Data System (ADS)

Cagnazzo, Chiara; Biondi, Riccardo; D'Errico, Miriam; Cherchi, Annalisa; Fierli, Federico; Lau, William K. M.

2016-04-01

Recent observational and modeling analyses have explored the interaction between aerosols and the Indian summer monsoon precipitation on seasonal-to-interannual time scales. By using global scale climate model simulations, we show that when increased aerosol loading is found on the Himalayas slopes in the premonsoon period (April-May), intensification of early monsoon rainfall over India and increased low-level westerly flow follow, in agreement with the elevated-heat-pump (EHP) mechanism. The increase in rainfall during the early monsoon season has a cooling effect on the land surface that may also be amplified through solar dimming (SD) by more cloudiness and aerosol loading with subsequent reduction in monsoon rainfall over India. We extend this analyses to a subset of CMIP5 climate model simulations. Our results suggest that 1) absorbing aerosols, by influencing the seasonal variability of the Indian summer monsoon with the discussed time-lag, may act as a source of predictability for the Indian Summer Monsoon and 2) if the EHP and SD effects are operating also in a number of state-of-the-art climate models, their inclusion could potentially improve seasonal forecasts.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Penner, Joyce E.; Zhou, Cheng

Observation-based studies have shown that the aerosol cloud lifetime effect or the increase of cloud liquid water path (LWP) with increased aerosol loading may have been overestimated in climate models. Here, we simulate shallow warm clouds on 05/27/2011 at the Southern Great Plains (SGP) measurement site established by Department of Energy's Atmospheric Radiation Measurement (ARM) Program using a single column version of a global climate model (Community Atmosphere Model or CAM) and a cloud resolving model (CRM). The LWP simulated by CAM increases substantially with aerosol loading while that in the CRM does not. The increase of LWP in CAMmore » is caused by a large decrease of the autoconversion rate when cloud droplet number increases. In the CRM, the autoconversion rate is also reduced, but this is offset or even outweighed by the increased evaporation of cloud droplets near cloud top, resulting in an overall decrease in LWP. Our results suggest that climate models need to include the dependence of cloud top growth and the evaporation/condensation process on cloud droplet number concentrations.« less

Load controller and method to enhance effective capacity of a photovoltaic power supply

DOEpatents

Perez, Richard

2000-01-01

A load controller and method are provided for maximizing effective capacity of a non-controllable, renewable power supply coupled to a variable electrical load also coupled to a conventional power grid. Effective capacity is enhanced by monitoring power output of the renewable supply and loading, and comparing the loading against the power output and a load adjustment threshold determined from an expected peak loading. A value for a load adjustment parameter is calculated by subtracting the renewable supply output and the load adjustment parameter from the current load. This value is then employed to control the variable load in an amount proportional to the value of the load control parameter when the parameter is within a predefined range. By so controlling the load, the effective capacity of the non-controllable, renewable power supply is increased without any attempt at operational feedback control of the renewable supply. The renewable supply may comprise, for example, a photovoltaic power supply or a wind-based power supply.

Effect of Arctic Amplification on Design Snow Loads in Alaska

DTIC Science & Technology

2016-09-01

snow water equivalent UFC Unified Facilities Criteria UTC Coordinated Universal Time Keywords: Alaska, Arctic amplification, climate change...extreme value analysis, snow loads, snow water equivalent , SWE Acknowledgements: This work was conducted with support from the Strategic... equivalent (SWE) of the snowpack. We acquired SWE data from a number of sources that provide automatic or manual observations, reanalysis data, or

Vernal keratoconjunctivitis in school children in Rwanda and its association with socio-economic status: a population-based survey.

PubMed

Smedt, Stefan De; Nkurikiye, John; Fonteyne, Yannick; Hogewoning, Arjan; Esbroeck, Marjan Van; Bacquer, Dirk De; Tuft, Stephen; Gilbert, Clare; Delanghe, Joris; Kestelyn, Philippe

2011-10-01

Vernal keratoconjunctivitis (VKC) is an allergic eye disease and an important cause of hospital referral among children in Africa and Asia. Hospital-based studies have suggested a role for parasites in its pathogenesis. To determine the prevalence and risk factors for VKC in Central Africa, we conducted a nested population-based case control study in Rwanda, involving randomly selected primary schools from different environments (rural/urban) and climate. A prevalence of VKC of 4.0% (95% confidence interval 3.3-4.7%) was found among 3,041 children studied (participation rate 94.7%). The intestinal parasitic burden was not related to VKC. Besides hot dry climate (odds ratio [OR] = 1.5, P = 0.05) and male gender (OR = 1.7, P = 0.005), multivariate analysis identified higher economic status as a risk for VKC (OR = 1.4, P = 0.005). The effect on VKC of higher economic status appears not to act through differences in parasitic intestinal load.

Vernal Keratoconjunctivitis in School Children in Rwanda and Its Association with Socio-Economic Status: A Population-Based Survey

PubMed Central

Smedt, Stefan De; Nkurikiye, John; Fonteyne, Yannick; Hogewoning, Arjan; Esbroeck, Marjan Van; Bacquer, Dirk De; Tuft, Stephen; Gilbert, Clare; Delanghe, Joris; Kestelyn, Philippe

2011-01-01

Vernal keratoconjunctivitis (VKC) is an allergic eye disease and an important cause of hospital referral among children in Africa and Asia. Hospital-based studies have suggested a role for parasites in its pathogenesis. To determine the prevalence and risk factors for VKC in Central Africa, we conducted a nested population-based case control study in Rwanda, involving randomly selected primary schools from different environments (rural/urban) and climate. A prevalence of VKC of 4.0% (95% confidence interval 3.3–4.7%) was found among 3,041 children studied (participation rate 94.7%). The intestinal parasitic burden was not related to VKC. Besides hot dry climate (odds ratio [OR] = 1.5, P = 0.05) and male gender (OR = 1.7, P = 0.005), multivariate analysis identified higher economic status as a risk for VKC (OR = 1.4, P = 0.005). The effect on VKC of higher economic status appears not to act through differences in parasitic intestinal load. PMID:21976577

Lake Tahoe

EPA Pesticide Factsheets

Information on the Lake Tahoe watershed, EPA's protection efforts, water quality issues, effects of climate change, Lake Tahoe Total Maximum Daily Load (TMDL), EPA-sponsored projects, list of partner agencies.

Impacts of climate on shrubland fuels and fire behavior in the Owyhee Basin, Idaho

NASA Astrophysics Data System (ADS)

Vogelmann, J. E.; Shi, H.; Hawbaker, T.; Li, Z.

2013-12-01

There is evidence that wildland fire is increasing as a function of global change. However, fire activity is spatially, temporally and ecologically variable across the globe, and our understanding of fire risk and behavior in many ecosystems is limited. After a series of severe fire seasons that occurred during the late 1990's in the western United States, the LANDFIRE program was developed with the goals of providing the fire community with objective spatial fuel data for assessing wildland fire risk. Even with access to the data provided by LANDFIRE, assessing fire behavior in shrublands in sagebrush-dominated ecosystems of the western United States has proven especially problematic, in part due to the complex nature of the vegetation, the variable influence of understory vegetation including invasive species (e.g. cheatgrass), and prior fire history events. Climate is undoubtedly playing a major role, affecting the intra- and inter-annual variability in vegetation conditions, which in turn impacts fire behavior. In order to further our understanding of climate-vegetation-fire interactions in shrublands, we initiated a study in the Owyhee Basin, which is located in southwestern Idaho and adjacent Nevada. Our goals include: (1) assessing the relationship between climate and vegetation condition, (2) quantifying the range of temporal variability in grassland and shrubland fuel loads, (3) identifying methods to operationally map the variability in fuel loads, and (4) assessing how the variability in fuel loads affect fire spread simulations. To address these goals, we are using a wide variety of geospatial data, including remotely sensed time-series data sets derived from MODIS and Landsat, and climate data from DAYMET and PRISM. Remotely-sensed information is used to characterize climate-induced temporal variability in primary productivity in the Basin, where fire spread can be extensive after senescence when dry vegetation is added to dead fuel loads. Gridded climate data indicate that this area has become warmer and dryer over the previous three decades. We have also observed that fires are especially prevalent in areas that have high Normalized Difference Vegetation Index (NDVI) values in the spring, followed by low NDVI in the summer. At present we are concentrating on the temporally rich MODIS data to map spatial and temporal variability in live fuel loads. To translate NDVI to biomass, we are scaling the range of biomass values using data from the literature. We assume that departure from maximum NDVI, typically occurring during spring, to NDVI values later in the season are related to the proportion of live biomass transferred to dead biomass, which burns more readily than green biomass. Using the FARSITE fire spread model, our initial simulations show that the conversion from live herbaceous fuel to dead fuel increases the burn area by 30% compared with using default static fuel parameters. This indicates that current fuel models underestimate fire spread and areas that could potentially burn. Our study also indicates that a combined remote sensing product with good temporal resolution (MODIS) and spatial resolution (Landsat) is necessary to provide accurate information on the fuel dynamics in shrublands.

Archaeobotanical evidence for climate as a driver of ecological community change across the anthropocene boundary.

PubMed

Ellis, Christopher J; Yahr, Rebecca; Belinchón, Rocío; Coppins, Brian J

2014-07-01

The biodiversity response to climate change is a major focus in conservation research and policy. Predictive models that are used to project the impact of climate change scenarios - such as bioclimatic envelope models - are widely applied and have come under severe scrutiny. Criticisms of such models have focussed on at least two problems. First, there is an assumption that climate is the primary driver of observed species distributions ('climatic equilibrium'), when other biogeographical controls are often reliably established. Second, a species' sensitivity to macroclimate may become less relevant when impacts are down-scaled to a local level, incorporating a modifying effect of species interactions structuring communities. This article examines the role of different drivers (climate, pollution and landscape habitat structure) in explaining spatial community variation for a widely applied bioindicator group: lichen epiphytes. To provide an analysis free of 'legacy effects' (e.g. formerly higher pollution loads), the study focused on hazel stems as a relatively short-lived and recently colonized substratum. For communities during the present day, climate is shown to interact with stem size/age as the most likely explanation of community composition, thus coupling a macroclimatic and community-scale effect. The position of present-day communities was projected into ordination space for eight sites in England and compared to the position of historical epiphyte communities from the same sites, reconstructed using preserved hazel wattles dating mainly to the 16th Century. This comparison of community structure for the late- to post-Mediaeval period, with the post-Industrial period, demonstrated a consistent shift among independent sites towards warmer and drier conditions, concurrent with the end of the Little Ice Age. Long-term temporal sensitivity of epiphyte communities to climate variation thus complements spatial community patterns. If more widely applied, preserved lichen epiphytes have potential to generate new baseline conditions of environment and biodiversity for preindustrial lowland Europe. © 2014 John Wiley & Sons Ltd.

Difference in tree growth responses to climate at the upper treeline: Qilian Juniper in the Anyemaqen Mountains.

PubMed

Peng, Jianfeng; Gou, Xiaohua; Chen, Fahu; Li, Jinbao; Liu, Puxing; Zhang, Yong; Fang, Keyan

2008-08-01

Three ring-width chronologies were developed from Qilian Juniper (Sabina przewalskii Kom.) at the upper treeline along a west-east gradient in the Anyemaqen Mountains. Most chronological statistics, except for mean sensitivity (MS), decreased from west to east. The first principal component (PC1) loadings indicated that stands in a similar climate condition were most important to the variability of radial growth. PC2 loadings decreased from west to east, suggesting the difference of tree-growth between eastern and western Anyemaqen Mountains. Correlations between standard chronologies and climatic factors revealed different climatic influences on radial growth along a west-east gradient in the study area. Temperature of warm season (July-August) was important to the radial growth at the upper treeline in the whole study area. Precipitation of current May was an important limiting factor of tree growth only in the western (drier) upper treeline, whereas precipitation of current September limited tree growth in the eastern (wetter) upper treeline. Response function analysis results showed that there were regional differences between tree growth and climatic factors in various sampling sites of the whole study area. Temperature and precipitation were the important factors influencing tree growth in western (drier) upper treeline. However, tree growth was greatly limited by temperature at the upper treeline in the middle area, and was more limited by precipitation than temperature in the eastern (wetter) upper treeline.

Aggregate Load Controllers and Associated Methods

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chassin, David P.

Aggregate load controllers and associated methods are described. According to one aspect, a method of operating an aggregate load controller includes using an aggregate load controller having an initial state, applying a stimulus to a plurality of thermostatic controllers which are configured to control a plurality of respective thermostatic loads which receive electrical energy from an electrical utility to operate in a plurality of different operational modes, accessing data regarding a response of the thermostatic loads as a result of the applied stimulus, using the data regarding the response, determining a value of at least one design parameter of themore » aggregate load controller, and using the determined value of the at least one design parameter, configuring the aggregate load controller to control amounts of the electrical energy which are utilized by the thermostatic loads.« less

Rapid increase in log populations in drought-stressed mixed-conifer and ponderosa pine forests in northern Arizona

Treesearch

Joseph L. Ganey; Scott C. Vojta

2012-01-01

Down logs provide important ecosystem services in forests and affect surface fuel loads and fire behavior. Amounts and kinds of logs are influenced by factors such as forest type, disturbance regime, forest man-agement, and climate. To quantify potential short-term changes in log populations during a recent global- climate-change type drought, we sampled logs in mixed-...

Responses of stream nitrate and DOC loadings to hydrological forcing and climate change in an upland forest of the northeastern United States

Treesearch

Stephen D. Sebestyen; Elizabeth W. Boyer; James B. Shanley

2009-01-01

In coming decades, higher annual temperatures, increased growing season length, and increased dormant season precipitation are expected across the northeastern United States in response to anthropogenic forcing of global climate. We synthesized long-term stream hydrochemical data from the Sleepers River Research Watershed in Vermont, United States, to explore the...

Sediment Transport Variability in Global Rivers: Implications for the Interpretation of Paleoclimate Signals

NASA Astrophysics Data System (ADS)

Syvitski, J. P.; Hutton, E. W.

2001-12-01

A new numerical approach (HydroTrend, v.2) allows the daily flux of sediment to be estimated for any river, whether gauged or not. The model can be driven by actual climate measurements (precipitation, temperature) or with statistical estimates of climate (modeled climate, remotely-sensed climate). In both cases, the character (e.g. soil depth, relief, vegetation index) of the drainage terrain is needed to complete the model domain. The HydroTrend approach allows us to examine the effects of climate on the supply of sediment to continental margins, and the nature of supply variability. A new relationship is defined as: $Qs = f (Psi) Qs-bar (Q/Q-bar)c+-σ where Qs-bar is the long-term sediment load, Q-bar is the long-term discharge, c and sigma are mean and standard deviation of the inter-annual variability of the rating coefficient, and Psi captures the measurement errors associated with Q and Qs, and the annual transients, affecting the supply of sediment including sediment and water source, and river (flood wave) dynamics. F = F(Psi, s). Smaller-discharge rivers have larger values of s, and s asymptotes to a small but consistent value for larger-discharge rivers. The coefficient c is directly proportional to the long-term suspended load (Qs-bar) and basin relief (R), and inversely proportional to mean annual temperature (T). sigma is directly proportional to the mean annual discharge. The long-term sediment load is given by: Qs-bar = a R1.5 A0.5 TT $ where a is a global constant, A is basin area; and TT is a function of mean annual temperature. This new approach provides estimates of sediment flux at the dynamic (daily) level and provides us a means to experiment on the sensitivity of marine sedimentary deposits in recording a paleoclimate signal. In addition the method provides us with spatial estimates for the flux of sediment to the coastal zone at the global scale.

How is the River Water Quality Response to Climate Change Impacts?

NASA Astrophysics Data System (ADS)

Nguyen, T. T.; Willems, P.

2015-12-01

Water quality and its response to climate change have been become one of the most important issues of our society, which catches the attention of many scientists, environmental activists and policy makers. Climate change influences the river water quality directly and indirectly via rainfall and air temperature. For example, low flow decreases the volume of water for dilution and increases the residence time of the pollutants. By contrast, high flow leads to increases in the amount of pollutants and sediment loads from catchments to rivers. The changes in hydraulic characteristics, i.e. water depth and velocity, affect the transportation and biochemical transformation of pollutants in the river water body. The high air temperature leads to increasing water temperature, shorter growing periods of different crops and water demands from domestic households and industries, which eventually effects the level of river pollution. This study demonstrates the quantification of the variation of the water temperature and pollutant concentrations along the Molse Neet river in the North East of Belgium as a result of the changes in the catchment rainfall-runoff, air temperature and nutrient loads. Firstly, four climate change scenarios were generated based on a large ensemble of available global and regional climate models and statistical downscaling based on a quantile perturbation method. Secondly, the climatic changes to rainfall and temperature were transformed to changes in the evapotranspiration and runoff flow through the conceptual hydrological model PDM. Thirdly, the adjustment in nutrient loads from agriculture due to rainfall and growing periods of crops were calculated by means of the semi-empirical SENTWA model. Water temperature was estimated from air temperature by a stochastic model separating the temperature into long-term annual and short-term residual components. Next, hydrodynamic and water quality models of the river, implemented in InfoWorks RS, were simulated for both historical (2000-2010) and projected future periods (2050-2060). The advection movement and physico-biochemical processes were considered for simulation of the following water quality variables: water temperature, dissolved oxygen, biological oxygen demand, ammonium, nitrate, nitrite and organic nitrogen.

Flow pathways and nutrient transport mechanisms drive hydrochemical sensitivity to climate change across catchments with different geology and topography

NASA Astrophysics Data System (ADS)

Crossman, J.; Futter, M. N.; Whitehead, P. G.; Stainsby, E.; Baulch, H. M.; Jin, L.; Oni, S. K.; Wilby, R. L.; Dillon, P. J.

2014-07-01

Hydrological processes determine the transport of nutrients and passage of diffuse pollution. Consequently, catchments are likely to exhibit individual hydrochemical responses (sensitivities) to climate change, which is expected to alter the timing and amount of runoff, and to impact in-stream water quality. In developing robust catchment management strategies and quantifying plausible future hydrochemical conditions it is therefore equally important to consider the potential for spatial variability in, and causal factors of, catchment sensitivity, as to explore future changes in climatic pressures. This study seeks to identify those factors which influence hydrochemical sensitivity to climate change. A perturbed physics ensemble (PPE), derived from a series of Global Climate Model (GCM) variants with specific climate sensitivities was used to project future climate change and uncertainty. Using the Integrated Catchment Model of Phosphorus Dynamics (INCA-P), we quantified potential hydrochemical responses in four neighbouring catchments (with similar land use but varying topographic and geological characteristics) in southern Ontario, Canada. Responses were assessed by comparing a 30 year baseline (1968-1997) to two future periods: 2020-2049 and 2060-2089. Although projected climate change and uncertainties were similar across these catchments, hydrochemical responses (sensitivity) were highly varied. Sensitivity was governed by soil type (influencing flow pathways) and nutrient transport mechanisms. Clay-rich catchments were most sensitive, with total phosphorus (TP) being rapidly transported to rivers via overland flow. In these catchments large annual reductions in TP loads were projected. Sensitivity in the other two catchments, dominated by sandy-loams, was lower due to a larger proportion of soil matrix flow, longer soil water residence times and seasonal variability in soil-P saturation. Here smaller changes in TP loads, predominantly increases, were projected. These results suggest that the clay content of soils could be a good indicator of the sensitivity of catchments to climatic input, and reinforces calls for catchment-specific management plans.

Flow pathways and nutrient transport mechanisms drive hydrochemical sensitivity to climate change across catchments with different geology and topography

NASA Astrophysics Data System (ADS)

Crossman, J.; Futter, M. N.; Whitehead, P. G.; Stainsby, E.; Baulch, H. M.; Jin, L.; Oni, S. K.; Wilby, R. L.; Dillon, P. J.

2014-12-01

Hydrological processes determine the transport of nutrients and passage of diffuse pollution. Consequently, catchments are likely to exhibit individual hydrochemical responses (sensitivities) to climate change, which are expected to alter the timing and amount of runoff, and to impact in-stream water quality. In developing robust catchment management strategies and quantifying plausible future hydrochemical conditions it is therefore equally important to consider the potential for spatial variability in, and causal factors of, catchment sensitivity, as it is to explore future changes in climatic pressures. This study seeks to identify those factors which influence hydrochemical sensitivity to climate change. A perturbed physics ensemble (PPE), derived from a series of global climate model (GCM) variants with specific climate sensitivities was used to project future climate change and uncertainty. Using the INtegrated CAtchment model of Phosphorus dynamics (INCA-P), we quantified potential hydrochemical responses in four neighbouring catchments (with similar land use but varying topographic and geological characteristics) in southern Ontario, Canada. Responses were assessed by comparing a 30 year baseline (1968-1997) to two future periods: 2020-2049 and 2060-2089. Although projected climate change and uncertainties were similar across these catchments, hydrochemical responses (sensitivities) were highly varied. Sensitivity was governed by quaternary geology (influencing flow pathways) and nutrient transport mechanisms. Clay-rich catchments were most sensitive, with total phosphorus (TP) being rapidly transported to rivers via overland flow. In these catchments large annual reductions in TP loads were projected. Sensitivity in the other two catchments, dominated by sandy loams, was lower due to a larger proportion of soil matrix flow, longer soil water residence times and seasonal variability in soil-P saturation. Here smaller changes in TP loads, predominantly increases, were projected. These results suggest that the clay content of soils could be a good indicator of the sensitivity of catchments to climatic input, and reinforces calls for catchment-specific management plans.

Tectonic and climatic controls on continental depositional facies in the Karoo Basin of northern Natal, South Africa

NASA Astrophysics Data System (ADS)

Turner, Brian R.

1986-02-01

The eastern Karoo Basin, South Africa, contains a thick sequence of terrigenous clastic sediments comprising a meanderbelt facies, braided channel facies divided into coarse and fine subfacies, fluviolacustrine facies and aeolian facies. Depositional trends and changes in fluvial style reflect a progressive increase in aridity of the climate under stable tectonic conditions, interrupted by two phases of source area tectonism and the development of fine and coarse clastic wedges of the braided channel subfacies; the latter signifying a short interlude of cool, wet conditions. The fine braided channel subfacies occurs in the upper part of the meanderbelt facies, which was deposited by ephemeral, meandering mixed-load streams of variable discharge and sinuosity, under dry, semi-arid climatic conditions. These deposited complex, internally discordant channel sands and well-developed levee deposits. Following deposition of the coarse braided channel subfacies semi-arid conditions returned and fluvial deposition was dominated by ephemeral, straight to slightly sinuous mixed load streams characterised by simple channel sand bodies. As the aridity of the climate increased, the streams became more localised and carried an increasing proportion of fines. Interbedded with and overlying the fluvial deposits is a mudstone-dominated lacustrine sequence grading up into aeolian sands suggesting a playa lake-type situation. The general absence of evaporites from these sediments is attributed to the fresh nature of the lake waters, as evidenced by the freshwater aquatic organisms and clay-mineral suite, the lack of adequate inflow for solute accumulation and the removal of dust impregnated by salts from the surface of the dry lake bed during the dry season by superheated, upward-spiralling columns of air. Broadly similar environments to the fluvio-lacustrine and aeolian facies sequence are to be found in the Lake Eyre Basin of central Australia and the Okavango "delta" of northern Botswana. The Okavango "delta" model has an important bearing on patterns of fluvial sedimentation in arid regions since it shows many characteristics of temperate, well-vegetated anastomosed fluvial systems despite its location in the Kalahari Desert.

Trends in Marine Debris along the U.S. Pacific Coast and Hawai’i 1998-2007

USGS Publications Warehouse

Ribic, Christine; Seba B. Sheavly,; Rugg, David J.; Erdmann, Eric S.

2012-01-01

We assessed amounts, composition, and trends of marine debris for the U.S. Pacific Coast and Hawai’i using National Marine Debris Monitoring Program data. Hawai’i had the highest debris loads; the North Pacific Coast region had the lowest debris loads. The Southern California Bight region had the highest land-based debris loads. Debris loads decreased over time for all source categories in all regions except for land-based and general-source loads in the North Pacific Coast region, which were unchanged. General-source debris comprised 30–40% of the items in all regions. Larger local populations were associated with higher land-based debris loads across regions; the effect declined at higher population levels. Upwelling affected deposition of ocean-based and general-source debris loads but not land-based loads along the Pacific Coast. LNSO decreased debris loads for both land-based and ocean-based debris but not general-source debris in Hawai’i, a more complex climate-ocean effect than had previously been found.

Study on load forecasting to data centers of high power density based on power usage effectiveness

NASA Astrophysics Data System (ADS)

Zhou, C. C.; Zhang, F.; Yuan, Z.; Zhou, L. M.; Wang, F. M.; Li, W.; Yang, J. H.

2016-08-01

There is usually considerable energy consumption in data centers. Load forecasting to data centers is in favor of formulating regional load density indexes and of great benefit to getting regional spatial load forecasting more accurately. The building structure and the other influential factors, i.e. equipment, geographic and climatic conditions, are considered for the data centers, and a method to forecast the load of the data centers based on power usage effectiveness is proposed. The cooling capacity of a data center and the index of the power usage effectiveness are used to forecast the power load of the data center in the method. The cooling capacity is obtained by calculating the heat load of the data center. The index is estimated using the group decision-making method of mixed language information. An example is given to prove the applicability and accuracy of this method.

Potential climate effect of mineral aerosols over West Africa: Part II—contribution of dust and land cover to future climate change

NASA Astrophysics Data System (ADS)

Ji, Zhenming; Wang, Guiling; Yu, Miao; Pal, Jeremy S.

2018-04-01

Mineral dust aerosols are an essential component of climate over West Africa, however, little work has been performed to investigate their contributions to potential climate change. A set of regional climate model experiments with and without mineral dust processes and land cover changes is performed to evaluate their climatic effects under the Representative Concentration Pathway 8.5 for two global climate models. Results suggest surface warming to be in the range of 4-8 °C by the end of the century (2081-2100) over West Africa with respect to the present day (1981-2000). The presence of mineral dusts dampens the warming by 0.1-1 °C in all seasons. Accounting for changes in land cover enhances the warming over the north of Sahel and dampens it to the south in spring and summer; however, the magnitudes are smaller than those resulting from dusts. Overall dust loadings are projected to increase, with the greatest increase occurring over the Sahara and Sahel in summer. Accounting for land cover changes tends to reduce dust loadings over the southern Sahel. Future precipitation is projected to decrease by 5-40 % in the western Sahara and Sahel and increase by 10-150 % over the eastern Sahel and Guinea Coast in JJA. A dipole pattern of future precipitation changes is attributed to dust effects, with decrease in the north by 5-20 % and increase by 5-20 % in the south. Future changes in land cover result in a noisy non-significant response with a tendency for slight wetting in MAM, JJA, and SON and drying in DJF.

Continent-wide risk assessment for the establishment of nonindigenous species in Antarctica

PubMed Central

Chown, Steven L.; Huiskes, Ad H. L.; Gremmen, Niek J. M.; Lee, Jennifer E.; Terauds, Aleks; Crosbie, Kim; Frenot, Yves; Hughes, Kevin A.; Imura, Satoshi; Kiefer, Kate; Lebouvier, Marc; Raymond, Ben; Tsujimoto, Megumu; Ware, Chris; Van de Vijver, Bart; Bergstrom, Dana Michelle

2012-01-01

Invasive alien species are among the primary causes of biodiversity change globally, with the risks thereof broadly understood for most regions of the world. They are similarly thought to be among the most significant conservation threats to Antarctica, especially as climate change proceeds in the region. However, no comprehensive, continent-wide evaluation of the risks to Antarctica posed by such species has been undertaken. Here we do so by sampling, identifying, and mapping the vascular plant propagules carried by all categories of visitors to Antarctica during the International Polar Year's first season (2007–2008) and assessing propagule establishment likelihood based on their identity and origins and on spatial variation in Antarctica's climate. For an evaluation of the situation in 2100, we use modeled climates based on the Intergovernmental Panel on Climate Change's Special Report on Emissions Scenarios Scenario A1B [Nakićenović N, Swart R, eds (2000) Special Report on Emissions Scenarios: A Special Report of Working Group III of the Intergovernmental Panel on Climate Change (Cambridge University Press, Cambridge, UK)]. Visitors carrying seeds average 9.5 seeds per person, although as vectors, scientists carry greater propagule loads than tourists. Annual tourist numbers (∼33,054) are higher than those of scientists (∼7,085), thus tempering these differences in propagule load. Alien species establishment is currently most likely for the Western Antarctic Peninsula. Recent founder populations of several alien species in this area corroborate these findings. With climate change, risks will grow in the Antarctic Peninsula, Ross Sea, and East Antarctic coastal regions. Our evidence-based assessment demonstrates which parts of Antarctica are at growing risk from alien species that may become invasive and provides the means to mitigate this threat now and into the future as the continent's climate changes. PMID:22393003

Significance of aerosol radiative effect in energy balance control on global precipitation change

DOE Office of Scientific and Technical Information (OSTI.GOV)

Suzuki, Kentaroh; Stephens, Graeme L.; Golaz, Jean-Christophe

Historical changes of global precipitation in the 20th century simulated by a climate model are investigated. The results simulated with alternate configurations of cloud microphysics are analyzed in the context of energy balance controls on global precipitation, where the latent heat changes associated with the precipitation change is nearly balanced with changes to atmospheric radiative cooling. The atmospheric radiative cooling is dominated by its clear-sky component, which is found to correlate with changes to both column water vapor and aerosol optical depth (AOD). The water vapor-dependent component of the clear-sky radiative cooling is then found to scale with global temperaturemore » change through the Clausius–Clapeyron relationship. This component results in a tendency of global precipitation increase with increasing temperature at a rate of approximately 2%K -1. Another component of the clear-sky radiative cooling, which is well correlated with changes to AOD, is also found to vary in magnitude among different scenarios with alternate configurations of cloud microphysics that controls the precipitation efficiency, a major factor influencing the aerosol scavenging process that can lead to different aerosol loadings. These results propose how different characteristics of cloud microphysics can cause different aerosol loadings that in turn perturb global energy balance to significantly change global precipitation. This implies a possible coupling of aerosol–cloud interaction with aerosol–radiation interaction in the context of global energy balance.« less

Significance of aerosol radiative effect in energy balance control on global precipitation change

DOE PAGES

Suzuki, Kentaroh; Stephens, Graeme L.; Golaz, Jean-Christophe

2017-10-17

Historical changes of global precipitation in the 20th century simulated by a climate model are investigated. The results simulated with alternate configurations of cloud microphysics are analyzed in the context of energy balance controls on global precipitation, where the latent heat changes associated with the precipitation change is nearly balanced with changes to atmospheric radiative cooling. The atmospheric radiative cooling is dominated by its clear-sky component, which is found to correlate with changes to both column water vapor and aerosol optical depth (AOD). The water vapor-dependent component of the clear-sky radiative cooling is then found to scale with global temperaturemore » change through the Clausius–Clapeyron relationship. This component results in a tendency of global precipitation increase with increasing temperature at a rate of approximately 2%K -1. Another component of the clear-sky radiative cooling, which is well correlated with changes to AOD, is also found to vary in magnitude among different scenarios with alternate configurations of cloud microphysics that controls the precipitation efficiency, a major factor influencing the aerosol scavenging process that can lead to different aerosol loadings. These results propose how different characteristics of cloud microphysics can cause different aerosol loadings that in turn perturb global energy balance to significantly change global precipitation. This implies a possible coupling of aerosol–cloud interaction with aerosol–radiation interaction in the context of global energy balance.« less

Modeling hydrology, groundwater recharge and non-point nitrate loadings in the Himalayan Upper Yamuna basin.

PubMed

Narula, Kapil K; Gosain, A K

2013-12-01

The mountainous Himalayan watersheds are important hydrologic systems responsible for much of the water supply in the Indian sub-continent. These watersheds are increasingly facing anthropogenic and climate-related pressures that impact spatial and temporal distribution of water availability. This study evaluates temporal and spatial distribution of water availability including groundwater recharge and quality (non-point nitrate loadings) for a Himalayan watershed, namely, the Upper Yamuna watershed (part of the Ganga River basin). The watershed has an area of 11,600 km(2) with elevation ranging from 6300 to 600 m above mean sea level. Soil and Water Assessment Tool (SWAT), a physically-based, time-continuous model, has been used to simulate the land phase of the hydrological cycle, to obtain streamflows, groundwater recharge, and nitrate (NO3) load distributions in various components of runoff. The hydrological SWAT model is integrated with the MODular finite difference groundwater FLOW model (MODFLOW), and Modular 3-Dimensional Multi-Species Transport model (MT3DMS), to obtain groundwater flow and NO3 transport. Validation of various modules of this integrated model has been done for sub-basins of the Upper Yamuna watershed. Results on surface runoff and groundwater levels obtained as outputs from simulation show a good comparison with the observed streamflows and groundwater levels (Nash-Sutcliffe and R(2) correlations greater than +0.7). Nitrate loading obtained after nitrification, denitrification, and NO3 removal from unsaturated and shallow aquifer zones is combined with groundwater recharge. Results for nitrate modeling in groundwater aquifers are compared with observed NO3 concentration and are found to be in good agreement. The study further evaluates the sensitivity of water availability to climate change. Simulations have been made with the weather inputs of climate change scenarios of A2, B2, and A1B for end of the century. Water yield estimates under climate change scenarios have been made and implications on groundwater and groundwater quality have been assessed. The delicate groundwater resource balance that connects livelihoods of millions of people seems to be under tremendously increasing pressure due to the dynamic conditions of the natural environment of the region and the future climate changes. Copyright © 2013 Elsevier B.V. All rights reserved.

Investigation of Optimal Control Allocation for Gust Load Alleviation in Flight Control

NASA Technical Reports Server (NTRS)

Frost, Susan A.; Taylor, Brian R.; Bodson, Marc

2012-01-01

Advances in sensors and avionics computation power suggest real-time structural load measurements could be used in flight control systems for improved safety and performance. A conventional transport flight control system determines the moments necessary to meet the pilot's command, while rejecting disturbances and maintaining stability of the aircraft. Control allocation is the problem of converting these desired moments into control effector commands. In this paper, a framework is proposed to incorporate real-time structural load feedback and structural load constraints in the control allocator. Constrained optimal control allocation can be used to achieve desired moments without exceeding specified limits on monitored load points. Minimization of structural loads by the control allocator is used to alleviate gust loads. The framework to incorporate structural loads in the flight control system and an optimal control allocation algorithm will be described and then demonstrated on a nonlinear simulation of a generic transport aircraft with flight dynamics and static structural loads.

Sediment transport dynamics in the Central Himalaya: assessing during monsoon the erosion processes signature in the daily suspended load of the Narayani river

NASA Astrophysics Data System (ADS)

Morin, Guillaume; Lavé, Jérôme; Lanord, Christian France; Prassad Gajurel, Ananta

2017-04-01

The evolution of mountainous landscapes is the result of competition between tectonic and erosional processes. In response to the creation of topography by tectonics, fluvial, glacial, and hillslope denudation processes erode topography, leading to rock exhumation and sediment redistribution. When trying to better document the links between climate, tectonic, or lithologic controls in mountain range evolution, a detailed understanding of the influence of each erosion process in a given environment is fundamental. At the scale of a whole mountain range, a systematic survey and monitoring of all the geomorphologic processes at work can rapidly become difficult. An alternative approach can be provided by studying the characteristics and temporal evolution of the sediments exported out of the range. In central Himalaya, the Narayani watershed presents contrasted lithologic, geochemical or isotopic signatures of the outcropping rocks as well as of the erosional processes: this particular setting allows conducting such type of approach by partly untangling the myopic vision of the spatial integration at the watershed scale. Based on the acquisition and analysis of a new dataset on the daily suspended load concentration and geochemical characteristics at the mountain outlet of one of the largest Himalayan rivers (drainage area = 30000 km2) bring several important results on Himalayan erosion, and on climatic and process controls. 1. Based on discrete depth sampling and on daily surface sampling of suspended load associated to flow characterization through ADCP measurements, we were first able to integrate sediment flux across a river cross-section and over time. We estimate for 2010 year an equivalent erosion rate of 1.8 +0.35/-0.2 mm/yr, and over the last 15 years, using past sediment load records from the DHM of Nepal, an equivalent erosion rate of 1.6 +0.3/-0.2 mm/yr. These rates are also in close agreement with the longer term ( 500 yrs) denudation rates of 1.7 mm/yr obtained from cosmonuclides in Narayani river sands (Lupker et al. 2012). Such stability of the erosion rates suggests that either buffering behaviour of this large watershed or broad spatial integration dampen the variability in monsoon strength or the sporadic nature of extreme mass-wasting events. 2. Paradoxically, the relatively high variability of the daily geochemical signature in suspended load and the apparent absence of delay between high rainfall episodes and sediment export suggest very short transfer time for silt and medium sand load, despite fluvial transfer distance of hundreds of kilometres between the sediment sources and the mountain outlet. This implies the absence of a buffering behaviour of the fluvial network and a very reactive fluvial system, which would be strongly supply limited relative to the fine sediment fraction. 3. By analysing sediments fluxes and using geochemical compositions in deltaD, carbonates content and TOC, which we propose as possible tracers for glacier- and soil-derived material, we show that glacier and soil erosion contribute to annual erosion budget to less than 10% and a few % respectively. Their imprints in Narayani sediment is only visible during the pre- and early monsoon before being overwhelmed by landslide-derived material during the monsoon. 4. Hillslope erosion by landslides appears therefore as the dominant erosional process in central Himalaya, and by comparing the sediment export history to a rainfall/runoff model, we confirm Gabet et al.'s (2004) inference that sediment export and possibly landslide triggering on Himalayan hillslopes are controlled both by pore pressure (depending on cumulated precipitation) and daily rainfall intensity.

Potential energy savings with exterior shades in large office buildings and the impact of discomfort glare

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hoffmann, Sabine; Lee, Eleanor

Exterior shades are highly efficient for reducing solar load in commercial buildings. Their impact on net energy use depends on the annual energy balance of heating, cooling, fan and lighting energy. This paper discusses the overall energy use intensity of various external shading systems for a prototypical large office building split into the different types of energy use and for different orientations and window sizes. Lighting energy was calculated for a constant lighting power as well as for dimmed lighting fixtures (daylighting control). In Section 3, slat angles and solar cut-off angles were varied for fixed exterior slat shading systems.more » While the most light-blocking shades performed best for the case without daylighting controls, the optimum cut-off angle with daylighting controls was found to be 30 deg for the office building prototype used in Chicago and Houston. For large window-to-wall (WWR) ratios, window related annual energy use could be reduced by at least 70 % without daylighting control and by a minimum of 86 % with daylighting control in average over all orientations. The occurrence of discomfort glare was is considered in Section 4 of the paper, which looks at the performance of commercially available exterior shading systems when an interior shade is used in addition to the exterior shade during hours when occupants would experience discomfort glare. Glare control impacts overall energy use intensity significantly for exterior shades with high transmittance, especially when daylighting controls are used. In these cases, exterior shades are only beneficial for window-to-wall areas ≥ 45% in the hot Houston climate. For smaller windows and in a heating/cooling climate like Chicago, exterior shades can increase energy consumption« less

Implications of Dynamic Loading and Changing Climate on Mercury Bioaccumulation in a Planktivorous Fish (Orthodon microlepidotus)

NASA Astrophysics Data System (ADS)

Carroll, R. W. H.; Flickinger, A.; Warwick, J. J.; Schumer, R.

2015-12-01

A bioenergetic and mercury (Hg) mass balance (BioHg) model is developed for the Sacramento blackfish (Orthodon microlepidotus), a filter feeding cyprinid found in northern California and Nevada. Attention focuses on the Lahontan Reservoir in northern Nevada, which receives a strong temporally varying load of dissolved methylmercury (DMeHg) from the Carson River. Hg loads are the result of contaminated bank erosion during high flows and diffusion from bottom sediments during low flows. Coupling of dynamic reservoir loading with periods of maximum plankton growth and maximum fish consumption rates are required to explain the largest body burdens observed in the planktivore. In contrast, the large body burdens cannot be achieved using average water column concentrations. The United States Bureau of Reclamation has produced future streamflow estimates for 2000-2099 using 112 CMIP3 climate projections and the Variable Infiltration Capacity (VIC) model. These are used to drive a fully dynamic Hg transport model to assess changes in contaminant loading to the reservoir and implications on planktivorous bioaccumulation. Model results suggest the future loads of DMeHg entering the Lahontan Reservoir will decrease most significantly in the spring and summer due to channel width increases and depth decreases in the Carson River which reduce bank erosion over the century. The modeled concentrations of DMeHg in the reservoir are expected to increase during the summer due to a decrease in reservoir volume affecting the concentrations more than the decrease in loads, and the model results show that bioaccumulation levels may increase in the upstream sections of the reservoir while maintaining contamination levels above the federal action limit for human consumption in the lower reservoir.

Force control compensation method with variable load stiffness and damping of the hydraulic drive unit force control system

NASA Astrophysics Data System (ADS)

Kong, Xiangdong; Ba, Kaixian; Yu, Bin; Cao, Yuan; Zhu, Qixin; Zhao, Hualong

2016-05-01

Each joint of hydraulic drive quadruped robot is driven by the hydraulic drive unit (HDU), and the contacting between the robot foot end and the ground is complex and variable, which increases the difficulty of force control inevitably. In the recent years, although many scholars researched some control methods such as disturbance rejection control, parameter self-adaptive control, impedance control and so on, to improve the force control performance of HDU, the robustness of the force control still needs improving. Therefore, how to simulate the complex and variable load characteristics of the environment structure and how to ensure HDU having excellent force control performance with the complex and variable load characteristics are key issues to be solved in this paper. The force control system mathematic model of HDU is established by the mechanism modeling method, and the theoretical models of a novel force control compensation method and a load characteristics simulation method under different environment structures are derived, considering the dynamic characteristics of the load stiffness and the load damping under different environment structures. Then, simulation effects of the variable load stiffness and load damping under the step and sinusoidal load force are analyzed experimentally on the HDU force control performance test platform, which provides the foundation for the force control compensation experiment research. In addition, the optimized PID control parameters are designed to make the HDU have better force control performance with suitable load stiffness and load damping, under which the force control compensation method is introduced, and the robustness of the force control system with several constant load characteristics and the variable load characteristics respectively are comparatively analyzed by experiment. The research results indicate that if the load characteristics are known, the force control compensation method presented in this paper has positive compensation effects on the load characteristics variation, i.e., this method decreases the effects of the load characteristics variation on the force control performance and enhances the force control system robustness with the constant PID parameters, thereby, the online PID parameters tuning control method which is complex needs not be adopted. All the above research provides theoretical and experimental foundation for the force control method of the quadruped robot joints with high robustness.

Assessing the effects of changes in land use and climate on runoff and sediment yields from a watershed in the Loess Plateau of China.

PubMed

Zuo, Depeng; Xu, Zongxue; Yao, Wenyi; Jin, Shuangyan; Xiao, Peiqing; Ran, Dachuan

2016-02-15

The changes in runoff and sediment load in the Loess Plateau of China have received considerable attention owing to their dramatic decline during recent decades. In this paper, the impacts of land-use and climate changes on water and sediment yields in the Huangfuchuan River basin (HFCRB) of the Loess Plateau are investigated by combined usage of statistical tests, hydrological modeling, and land-use maps. The temporal trends and abrupt changes in runoff and sediment loads during 1954-2012 are detected by using non-parametric Mann-Kendall and Pettitt tests. The land-use changes between 1980 and 2005 are determined by using transition matrix analysis, and the effects of land-use and climate changes on water and sediment yields are assessed by using the Soil and Water Assessment Tool (SWAT) hydrological model and four scenarios, respectively. The results show significant decreasing trends in both annual runoff and sediment loads, whereas slightly decreasing and significantly increasing trends are detected for annual precipitation and air temperature, respectively. 1984 is identified as the dividing year of the study period. The land-use changes between 1980 and 2005 show significant effects of the Grain for Green Project in China. Both land-use change and climate change have greater impact on the reduction of sediment yield than that of water. Water and sediment yields in the upstream region show more significant decreases than those in the downstream region under different effects. The results obtained in this study can provide useful information for water resource planning and management as well as soil and water conservation in the Loess Plateau region. Copyright © 2015 Elsevier B.V. All rights reserved.

Simulated building energy demand biases resulting from the use of representative weather stations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burleyson, Casey D.; Voisin, Nathalie; Taylor, Z. Todd

Numerical building models are typically forced with weather data from a limited number of “representative cities” or weather stations representing different climate regions. The use of representative weather stations reduces computational costs, but often fails to capture spatial heterogeneity in weather that may be important for simulations aimed at understanding how building stocks respond to a changing climate. We quantify the potential reduction in bias from using an increasing number of weather stations over the western U.S. The approach is based on deriving temperature and load time series using incrementally more weather stations, ranging from 8 to roughly 150, tomore » capture weather across different seasons. Using 8 stations, one from each climate zone, across the western U.S. results in an average absolute summertime temperature bias of 7.2°F with respect to a spatially-resolved gridded dataset. The mean absolute bias drops to 2.8°F using all available weather stations. Temperature biases of this magnitude could translate to absolute summertime mean simulated load biases as high as 13.8%, a significant error for capacity expansion planners who may use these types of simulations. Increasing the size of the domain over which biases are calculated reduces their magnitude as positive and negative biases may cancel out. Using 8 representative weather stations can lead to a 20-40% overestimation of peak building loads during both summer and winter. Using weather stations close to population centers reduces both mean and peak load biases. This approach could be used by others designing aggregate building simulations to understand the sensitivity to their choice of weather stations used to drive the models.« less

Suburban watershed nitrogen retention: Estimating the effectiveness of stormwater management structures

USGS Publications Warehouse

Koch, Benjamin J.; Febria, Catherine M.; Cooke, Roger M.; Hosen, Jacob D.; Baker, Matthew E.; Colson, Abigail R.; Filoso, Solange; Hayhoe, Katharine; Loperfido, J. V.; Stoner, Anne M.K.; Palmer, Margaret A.

2015-01-01

Expert knowledge indicated wide uncertainty in BMP performance, with N removal efficiencies ranging from <0% (BMP acting as a source of N during a rain event) to >40%. Experts believed that the amount of rain was the primary identifiable source of variability in BMP efficiency, which is relevant given climate projections of more frequent heavy rain events in the mid-Atlantic. To assess the extent to which those projected changes might alter N export from suburban BMPs and watersheds, we combined downscaled estimates of rainfall with distributions of N loads for different-sized rain events derived from our elicitation. The model predicted higher and more variable N loads under a projected future climate regime, suggesting that current BMP regulations for reducing nutrients may be inadequate in the future.

Climate-sensitive feedbacks between hillslope processes and fluvial erosion in sediment-driven incision models

NASA Astrophysics Data System (ADS)

Skov, Daniel S.; Egholm, David L.

2016-04-01

Surface erosion and sediment production seem to have accelerated globally as climate cooled in the Late Cenozoic, [Molnar, P. 2004, Herman et al 2013]. Glaciers emerged in many high mountain ranges during the Quaternary, and glaciation therefore represents a likely explanation for faster erosion in such places. Still, observations and measurements point to increases in erosion rates also in landscapes where erosion is driven mainly by fluvial processes [Lease and Ehlers (2013), Reusser (2004)]. Flume experiments and fieldwork have shown that rates of incision are to a large degree controlled by the sediment load of streams [e.g. Sklar and Dietrich (2001), Beer and Turowski (2015)]. This realization led to the formulation of sediment-flux dependent incision models [Sklar and Dietrich (2004)]. The sediment-flux dependence links incision in the channels to hillslope processes that supply sediment to the channels. The rates of weathering and soil transport on the hillslopes are processes that are likely to respond to changing temperatures, e.g. because of vegetation changes or the occurrence of frost. In this study, we perform computational landscape evolution experiments, where the coupling between fluvial incision and hillslope processes is accounted for by coupling a sediment-flux-dependent model for fluvial incision to a climate-dependent model for weathering and hillslope sediment transport. The computational experiments first of all demonstrate a strong positive feedback between channel and hillslope processes. In general, faster weathering leads to higher rates of channel incision, which further increases the weathering rates, mainly because of hillslope steepening. Slower weathering leads to the opposite result. The experiments also demonstrate, however, that the feedbacks vary significantly between different parts of a drainage network. For example, increasing hillslope sediment production may accelerate incision in the upper parts of the catchment, while at the same time the channel bed in the lower parts become shielded from incision by a perpetual sediment cover and incision stalls. These differences cause transients of erosion to migrate through the drainage network. Beer, Alexander R., and J. M. Turowski. "Bedload transport controls bedrock erosion under sediment-starved conditions." Earth Surface Dynamics 3.3 (2015): 291-309. Herman, Frédéric, et al. "Worldwide acceleration of mountain erosion under a cooling climate." Nature 504.7480 (2013): 423-426. Lease, Richard O., and Todd A. Ehlers. "Incision into the Eastern Andean plateau during Pliocene cooling." Science 341.6147 (2013): 774-776. Molnar, Peter. "Late Cenozoic increase in accumulation rates of terrestrial sediment: how might climate change have affected erosion rates?." Annu. Rev. Earth Planet. Sci. 32 (2004): 67-89. Reusser, Luke J., et al. "Rapid Late Pleistocene incision of Atlantic passive-margin river gorges." Science 305.5683 (2004): 499-502. Sklar, Leonard S., and William E. Dietrich. "Sediment and rock strength controls on river incision into bedrock." Geology 29.12 (2001): 1087-1090. Sklar, Leonard S., and William E. Dietrich. "A mechanistic model for river incision into bedrock by saltating bed load." Water Resources Research 40.6 (2004).

Direct and semi-direct effects of aerosol climatologies on long-term climate simulations over Europe

NASA Astrophysics Data System (ADS)

Schultze, Markus; Rockel, Burkhardt

2017-08-01

This study compares the direct and semi-direct aerosol effects of different annual cycles of tropospheric aerosol loads for Europe from 1950 to 2009 using the regional climate model COSMO-CLM, which is laterally forced by reanalysis data and run using prescribed, climatological aerosol optical properties. These properties differ with respect to the analysis strategy and the time window, and are then used for the same multi-decadal period. Five simulations with different aerosol loads and one control simulation without any tropospheric aerosols are integrated and compared. Two common limitations of our simulation strategy, to fully assess direct and semi-direct aerosol effects, are the applied observed sea surface temperatures and sea ice conditions, and the lack of short-term variations in the aerosol load. Nevertheless, the impact of different aerosol climatologies on common regional climate model simulations can be assessed. The results of all aerosol-including simulations show a distinct reduction in solar irradiance at the surface compared with that in the control simulation. This reduction is strongest in the summer season and is balanced primarily by a weakening of turbulent heat fluxes and to a lesser extent by a decrease in longwave emissions. Consequently, the seasonal mean surface cooling is modest. The temperature profile responses are characterized by a shallow near-surface cooling and a dominant warming up to the mid-troposphere caused by aerosol absorption. The resulting stabilization of stratification leads to reduced cloud cover and less precipitation. A decrease in cloud water and ice content over Central Europe in summer possibly reinforce aerosol absorption and thus strengthen the vertical warming. The resulting radiative forcings are positive. The robustness of the results was demonstrated by performing a simulation with very strong aerosol forcing, which lead to qualitatively similar results. A distinct added value over the default aerosol setup of Tanré et al. (1984) was found in the simulations with more recent aerosol data sets for solar irradiance. The improvements are largest under low cloud conditions, while overestimated cloud cover in all setups causes a common underestimation of low and medium values of solar irradiance. In addition, the prevalent cold bias in the COSMO-CLM is reduced in winter and spring when using updated aerosol data. Our results emphasize the importance of semi-direct aerosol effects, especially over Central Europe in terms of changes in turbulent fluxes and changes in cloud properties. We also suggest to replace the default Tanré et al. (1984) aerosol climatology with more recent and realistic data sets. Thereby, a better model performance in comparison to observations can be achieved, or the masking of model shortcomings due to a too strong direct aerosol forcing thus far is prevented.

Climate change and the EU Water Framework Directive: how to deal with indirect effects of changes in hydrology on water quality and ecology?

PubMed

Heerdt, G N J Ter; Schep, S A; Janse, J H; Ouboter, M

2007-01-01

In order to set ecological goals and determine measures for the European Water Framework Directive, the effects of climate change on lake ecosystems should be estimated. It is thought that the complexity of lake ecosystems makes this effect inherently unpredictable. However, models that deal with this complexity are available and well calibrated and tested. In this study we use the ecosystem model PCLake to demonstrate how climate change might affect the ecological status of a shallow peaty lake in 2050. With the model PCLake, combined with a long-term water and nutrient balance, it is possible to describe adequately the present status of the lake. Simulations of future scenarios with increasing precipitation, evaporation and temperature, showed that climate change will lead to higher nutrient loadings. At the same time, it will lead to lower critical loadings. Together this might cause the lake to shift easier from a clear water to a turbid state. The amount of algae, expressed as the concentration Chl-a, will increase, as a consequence turbidity will increase. The outcome of this study; increasing stability of the turbid state of the lake, and thus the need for more drastic measures, is consistent with some earlier studies.

Load control system. [for space shuttle external tank ground tests

NASA Technical Reports Server (NTRS)

Grosse, J. C.

1977-01-01

The load control system developed for the shuttle external structural tests is described. The system consists of a load programming/display module, and a load control module along with the following hydraulic system components: servo valves, dump valves, hydraulic system components, and servo valve manifold blocks. One load programming/display subsystem can support multiple load control subsystem modules.

Integrating Salmon Recovery, Clean Water Act Compliance ...

EPA Pesticide Factsheets

"The South Fork Nooksack River (SFNR) is an important tributary to the Nooksack River, Bellingham Bay, and the Salish Sea. The South Fork Nooksack River comprises one of the 22 independent populations of spring Chinook in the Puget Sound Chinook Evolutionarily Significant Unit (ESU), which are listed as threatened under the Endangered Species Act (ESA). The population is considered essential for recovery of the ESU. The SFNR has suffered from legacy impacts, temperature exceedances and fine sediment, due to forestry, agriculture, flood control, and transportation facilities. The temperature exceedances threaten spring Chinook salmon survival and as such under the Clean Water Act, this pollution must be addressed through a total maximum daily load (TMDL) regulatory program. Further, climate change is projected to cumulatively add to the existing legacy impacts. Millions of dollars are spent on salmon habitat restoration in the SFNR that primarily addresses these legacy impacts, but few if any restoration actions take climate change into direct consideration. The Nooksack Indian Tribe and USEPA-ORD jointly completed a climate change pilot research project that addresses legacy impacts, ESA recovery actions, CWA regulatory compliance, and salmon habitat restoration in one comprehensive project. The project evaluates how land use impacts, including altered hydrology, stream temperature, sediment dynamics, and flooding of adjacent river floodplains, combined with pr

Influence of Convection and Aerosol Pollution on Ice Cloud Particle Effective Radius

NASA Technical Reports Server (NTRS)

Jiang, J. H.; Su, H.; Zhai, C.; Massie, S. T.; Schoeberl, M. R.; Colarco, P. R.; Platnick, S.; Gu, Y.; Liou, K.-N.

2011-01-01

Satellite observations show that ice cloud effective radius (r(sub e)) increases with ice water content (IWC) but decreases with aerosol optical thickness (AOT). Using least-squares fitting to the observed data, we obtain an analytical formula to describe the variations of r(sub e) with IWC and AOT for several regions with distinct characteristics of r(sub e) -IWC-AOT relationships. As IWC directly relates to convective strength and AOT represents aerosol loading, our empirical formula provides a means to quantify the relative roles of dynamics and aerosols in controlling r(sub e) in different geographical regions, and to establish a framework for parameterization of aerosol effects on r(sub e) in climate models.

Evaluation of mercury loads from climate change projections

Treesearch

Paul Conrads; Paul M. Bradley; Stephen T. Benedict; Toby D. Feaster

2016-01-01

McTier Creek is a small coastal plain watershed located in Aiken County, South Carolina. McTier Creek forms part of the headwaters for the Edisto River basin, which is noted for having some of the highest recorded fish-tissue mercury concentrations in the United States. A simple water-quality load model, TOPLOAD, which was developed for McTier Creek, utilizes a mass...

[Measurement model of carbon emission from forest fire: a review].

PubMed

Hu, Hai-Qing; Wei, Shu-Jing; Jin, Sen; Sun, Long

2012-05-01

Forest fire is the main disturbance factor for forest ecosystem, and an important pathway of the decrease of vegetation- and soil carbon storage. Large amount of carbonaceous gases in forest fire can release into atmosphere, giving remarkable impacts on the atmospheric carbon balance and global climate change. To scientifically and effectively measure the carbonaceous gases emission from forest fire is of importance in understanding the significance of forest fire in the carbon balance and climate change. This paper reviewed the research progress in the measurement model of carbon emission from forest fire, which covered three critical issues, i. e., measurement methods of forest fire-induced total carbon emission and carbonaceous gases emission, affecting factors and measurement parameters of measurement model, and cause analysis of the uncertainty in the measurement of the carbon emissions. Three path selections to improve the quantitative measurement of the carbon emissions were proposed, i. e., using high resolution remote sensing data and improving algorithm and estimation accuracy of burned area in combining with effective fuel measurement model to improve the accuracy of the estimated fuel load, using high resolution remote sensing images combined with indoor controlled environment experiments, field measurements, and field ground surveys to determine the combustion efficiency, and combining indoor controlled environment experiments with field air sampling to determine the emission factors and emission ratio.

Climatic and ecological controls on variability of fire activity in the tropics and subtropics derived from satellite data

NASA Astrophysics Data System (ADS)

van der Werf, G. R.; Randerson, J. T.; Giglio, L.; Gobron, N.; Dolman, H. J.

2006-12-01

El Nino-Southern Oscillation-linked variations in biomass burning emissions substantially contribute to interannual variability in the growth rate of many trace gases, yet ecological and climatic controls on fire activity are not well known. We used satellite-derived datasets of biomass burning, precipitation rates, and net primary production (NPP) in the tropics and subtropics during 1998 through 2005 to investigate the factors that regulate interannual variability in fire emissions. In many xeric regions that have low levels of NPP, we found a positive relationship between precipitation, NPP, and fire activity, implying that fire in these regions is limited to years when precipitation allows for the build-up of sufficient biomass or fuel loads to allow fire spread. This was most evident in regions where mean annual precipitation was below approximately 600 mm / year, including xeric regions of Africa and Northern Australia. In contrast, in areas of the tropics undergoing active deforestation, including, Indonesia, Central America, and parts of South America we found a significant negative correlation between precipitation and fire activity during the dry season. This implies that human use of fire in these regions in the deforestation process is at least partly limited by periods when high moisture levels limit ignition and fire activity.

Mode, load, and specific climate impact from passenger trips.

PubMed

Borken-Kleefeld, Jens; Fuglestvedt, Jan; Berntsen, Terje

2013-07-16

The climate impact from a long-distance trip can easily vary by a factor of 10 per passenger depending on mode choice, vehicle efficiency, and occupancy. In this paper we compare the specific climate impact of long-distance car travel with coach, train, or air trips. We account for both, CO2 emissions and short-lived climate forcers. This particularly affects the ranking of aircraft's climate impact relative to other modes. We calculate the specific impact for the Global Warming Potential and the Global Temperature Change Potential, considering time horizons between 20 and 100 years, and compare with results accounting only for CO2 emissions. The car's fuel efficiency and occupancy are central whether the impact from a trip is as high as from air travel or as low as from train travel. These results can be used for carbon-offsetting schemes, mode choice and transportation planning for climate mitigation.

Climate change and peak demand for electricity: Evaluating policies for reducing peak demand under different climate change scenarios

NASA Astrophysics Data System (ADS)

Anthony, Abigail Walker

This research focuses on the relative advantages and disadvantages of using price-based and quantity-based controls for electricity markets. It also presents a detailed analysis of one specific approach to quantity based controls: the SmartAC program implemented in Stockton, California. Finally, the research forecasts electricity demand under various climate scenarios, and estimates potential cost savings that could result from a direct quantity control program over the next 50 years in each scenario. The traditional approach to dealing with the problem of peak demand for electricity is to invest in a large stock of excess capital that is rarely used, thereby greatly increasing production costs. Because this approach has proved so expensive, there has been a focus on identifying alternative approaches for dealing with peak demand problems. This research focuses on two approaches: price based approaches, such as real time pricing, and quantity based approaches, whereby the utility directly controls at least some elements of electricity used by consumers. This research suggests that well-designed policies for reducing peak demand might include both price and quantity controls. In theory, sufficiently high peak prices occurring during periods of peak demand and/or low supply can cause the quantity of electricity demanded to decline until demand is in balance with system capacity, potentially reducing the total amount of generation capacity needed to meet demand and helping meet electricity demand at the lowest cost. However, consumers need to be well informed about real-time prices for the pricing strategy to work as well as theory suggests. While this might be an appropriate assumption for large industrial and commercial users who have potentially large economic incentives, there is not yet enough research on whether households will fully understand and respond to real-time prices. Thus, while real-time pricing can be an effective tool for addressing the peak load problems, pricing approaches are not well suited to ensure system reliability. This research shows that direct quantity controls are better suited for avoiding catastrophic failure that results when demand exceeds supply capacity.

North African dust emissions and transport

NASA Astrophysics Data System (ADS)

Engelstaedter, Sebastian; Tegen, Ina; Washington, Richard

2006-11-01

The need for a better understanding of the role of atmospheric dust in the climate system and its impact on the environment has led to research of the underlying causes of dust variability in space and time in recent decades. North Africa is one of the largest dust producing regions in the world with dust emissions being highly variable on time scales ranging from diurnal to multiannual. Changes in the dust loading are expected to have an impact on regional and global climate, the biogeochemical cycle, and human environments. The development of satellite derived products of global dust distributions has improved our understanding of dust source regions and transport pathways in the recent years. Dust models are now capable of reproducing more realistic patterns of dust distributions due to an improved parameterization of land surface conditions. A recent field campaign has improved our understanding of the natural environment and emission processes of the most intense and persistent dust sources in the world, the Bodélé Depression in Chad. In situ measurements of dust properties during air craft observations in and down wind of source regions have led to new estimates of the radiative forcing effects which are crucial in predicting future climate change. With a focus on the North African desert regions, this paper provides a review of the understanding of dust source regions, the variability of dust emissions, climatic controls of dust entrainment and transport, the role of human impact on dust emission, and recent developments of global and regional dust models.

How phosphorus limitation can control climatic gas sources and sinks

NASA Astrophysics Data System (ADS)

Gypens, Nathalie; Borges, Alberto V.; Ghyoot, Caroline

2017-04-01

Since the 1950's, anthropogenic activities severely increased river nutrient loads in European coastal areas. Subsequent implementation of nutrient reduction policies have considerably reduced phosphorus (P) loads from mid-1980's, while nitrogen (N) loads were maintained, inducing a P limitation of phytoplankton growth in many eutrophied coastal areas such as the Southern Bight of the North Sea (SBNS). When dissolved inorganic phosphorous (DIP) is limiting, most phytoplankton organisms are able to indirectly acquire P from dissolved organic P (DOP). We investigate the impact of DOP use on the importance of phytoplankton production and atmospheric fluxes of CO2 and dimethylsulfide (DMS) in the SBNS from 1951 to 2007 using an extended version of the R-MIRO-BIOGAS model. This model includes a description of the ability of phytoplankton organisms to use DOP as a source of P. Results show that primary production can increase up to 70% due to DOP uptake in limiting DIP conditions. Consequently, simulated DMS emissions double while CO2 emissions to the atmosphere decrease, relative to the reference simulation without DOP uptake. At the end of the simulated period (late 2000's), the net direction of air-sea CO2 annual flux, changed from a source to a sink for atmospheric CO2 in response to use of DOP and increase of primary production.

Why do general circulation models overestimate the aerosol cloud lifetime effect? A case study comparing CAM5 and a CRM

NASA Astrophysics Data System (ADS)

Zhou, Cheng; Penner, Joyce E.

2017-01-01

Observation-based studies have shown that the aerosol cloud lifetime effect or the increase of cloud liquid water path (LWP) with increased aerosol loading may have been overestimated in climate models. Here, we simulate shallow warm clouds on 27 May 2011 at the southern Great Plains (SGP) measurement site established by the Department of Energy's (DOE) Atmospheric Radiation Measurement (ARM) program using a single-column version of a global climate model (Community Atmosphere Model or CAM) and a cloud resolving model (CRM). The LWP simulated by CAM increases substantially with aerosol loading while that in the CRM does not. The increase of LWP in CAM is caused by a large decrease of the autoconversion rate when cloud droplet number increases. In the CRM, the autoconversion rate is also reduced, but this is offset or even outweighed by the increased evaporation of cloud droplets near the cloud top, resulting in an overall decrease in LWP. Our results suggest that climate models need to include the dependence of cloud top growth and the evaporation/condensation process on cloud droplet number concentrations.

Reduced sediment transport in the Chinese Loess Plateau due to climate change and human activities.

PubMed

Yang, Xiaonan; Sun, Wenyi; Li, Pengfei; Mu, Xingmin; Gao, Peng; Zhao, Guangju

2018-06-14

The sediment load on the Chinese Loess Plateau has sharply decreased in recent years. However, the contribution of terrace construction and vegetation restoration projects to sediment discharge reduction remains uncertain. In this paper, eight catchments located in the Loess Plateau were chosen to explore the effects of different driving factors on sediment discharge changes during the period from the 1960s to 2012. Attribution approaches were applied to evaluate the effects of climate, terrace, and vegetation coverage changes on sediment discharge. The results showed that the annual sediment discharge decreased significantly in all catchments ranging from -0.007 to -0.039 Gt·yr -1 . Sediment discharge in most tributaries has shown abrupt changes since 1996, and the total sediment discharge was reduced by 60.1% during 1997-2012. We determined that increasing vegetation coverage was the primary factor driving the reductions in sediment loads since 1996 and accounted for 47.7% of the total reduction. Climate variability and terrace construction accounted for 9.1% and 18.6% of sediment discharge reductions, respectively. Copyright © 2018. Published by Elsevier B.V.

HOW THE LEED VENTILATION CREDIT IMPACTS ENERGY CONSUMPTION OF GSHP SYSTEMS A CASE STUDY FOR PRIMARY SCHOOLS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Xiaobing

2011-01-01

This paper presents a study on the impacts of increased outdoor air (OA) ventilation on the performance of ground-source heat pump (GSHP) systems that heat and cool typical primary schools. Four locations Phoenix, Miami, Seattle, and Chicago are selected in this study to represent different climate zones in the United States. eQUEST, an integrated building and HVAC system energy analysis program, is used to simulate a typical primary school and the GSHP system at the four locations with minimum and 30% more than minimum OA ventilation. The simulation results show that, without an energy recovery ventilator, the 30% more OAmore » ventilation results in an 8.0 13.3% increase in total GSHP system energy consumption at the four locations. The peak heating and cooling loads increase by 20.2 30% and 14.9 18.4%, respectively, at the four locations. The load imbalance of the ground heat exchanger is increased in hot climates but reduced in mild and cold climates.« less

Interannual and long-term changes in the trophic state of a multibasin lake: Effects of morphology, climate, winter aeration, and beaver activity

USGS Publications Warehouse

Robertson, Dale M.; Rose, William; Reneau, Paul C.

2016-01-01

Little St. Germain Lake (LSG), a relatively pristine multibasin lake in Wisconsin, USA, was examined to determine how morphologic (internal), climatic (external), anthropogenic (winter aeration), and natural (beaver activity) factors affect the trophic state (phosphorus, P; chlorophyll, CHL; and Secchi depth, SD) of each of its basins. Basins intercepting the main flow and external P sources had highest P and CHL and shallowest SD. Internal loading in shallow, polymictic basins caused P and CHL to increase and SD to decrease as summer progressed. Winter aeration used to eliminate winterkill increased summer internal P loading and decreased water quality, while reductions in upstream beaver impoundments had little effect on water quality. Variations in air temperature and precipitation affected each basin differently. Warmer air temperatures increased productivity throughout the lake and decreased clarity in less eutrophic basins. Increased precipitation increased P in the basins intercepting the main flow but had little effect on the isolated deep West Bay. These relations are used to project effects of future climatic changes on LSG and other temperate lakes.

Building Low Carbon Cities: Framework to Design and Evaluate Alternative Technologies and Policies for Land Use Planning

NASA Astrophysics Data System (ADS)

Hashimoto, S.; Hamano, H.; Fujita, T.; Hori, H.

2008-12-01

Annex I parties of the Kyoto Protocol are facing even greater pressures to fulfill their commitment for GHG reduction as they enter the first commitment period of the Kyoto Protocol 2008-2012. In Japanese context, one such challenge is to reduce CO2 emissions from the household and business sectors because CO2 emissions from the both sectors has increased by 12% and 20% respectively since 1990 while the industry has achieved 21% of CO2 emissions reduction. Land use planning, which, either directly or indirectly, controls appropriate uses for land within jurisdictions, might play very important roles to deal with CO2 reductions from the household and business sectors. In this research, aiming at effective reductions of air- conditioning energy consumption and resultant CO2 emissions from the household and business sectors, the framework to design and evaluate land use planning was developed. The design and evaluation processes embraced in this framework consist of GIS database, technology and policy inventory for planning, one- dimensional urban canopy model which evaluate urban climate at neighborhood level and air-conditioning load calculation procedure. The GIS database provides spatial information of target areas such as land use, building use and road networks, which, then, helps design alternative land use plans. The technology and policy inventory includes various planning options ranging from those for land over control to those for building energy control, which, combined with the GIS database, serves for planning process. The urban canopy model derives vertical profiles of local climate, such as temperature and humidity, using the information of land use, building height and so on, aided by the GIS database. Vertical profiles of the urban climate are then utilized to derive air-conditioning load and associated CO2 emissions for each building located in target areas. The framework developed was applied to the coastal district of Kawasaki, Japan, with an area of 40 square kilometers, for August 2006, to explore effective combinations of technologies and policies for land use planning. Six alternative land use policies were designed, including BaU in which current land use continues, and were, then, evaluated to seek more effective alternatives. Our findings suggested that about 541 MWh power and 204 tons of CO2 emission be saved at maximum by greening building sites, introducing water retentive pavement and installing energy-saving technologies for buildings in an appropriate manner.

Thermal Property Analysis of Axle Load Sensors for Weighing Vehicles in Weigh-in-Motion System

PubMed Central

Burnos, Piotr; Gajda, Janusz

2016-01-01

Systems which permit the weighing of vehicles in motion are called dynamic Weigh-in-Motion scales. In such systems, axle load sensors are embedded in the pavement. Among the influencing factors that negatively affect weighing accuracy is the pavement temperature. This paper presents a detailed analysis of this phenomenon and describes the properties of polymer, quartz and bending plate load sensors. The studies were conducted in two ways: at roadside Weigh-in-Motion sites and at a laboratory using a climate chamber. For accuracy assessment of roadside systems, the reference vehicle method was used. The pavement temperature influence on the weighing error was experimentally investigated as well as a non-uniform temperature distribution along and across the Weigh-in-Motion site. Tests carried out in the climatic chamber allowed the influence of temperature on the sensor intrinsic error to be determined. The results presented clearly show that all kinds of sensors are temperature sensitive. This is a new finding, as up to now the quartz and bending plate sensors were considered insensitive to this factor. PMID:27983704

Exterior Rigid Foam Insulation at the Edge of a Slab Foundation, Fresno, California (Fact Sheet)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

Exterior rigid foam insulation at the edge of the slab foundation was a unique feature for this low-load, unoccupied test house in a hot-dry climate and may be more appropriate for climates with higher heating loads. U.S. Department of Energy Building America research team IBACOS worked with National Housing Quality Award winner Wathen-Castanos Hybrid Homes, Inc., to assess the performance of this feature in a single-family detached ranch house with three bedrooms and two full bathrooms constructed on a slab-on-grade foundation in Fresno, California. One challenge during installation of the system was the attachment of the butyl flashing to themore » open framing. To solve this constructability issue, the team added a nailer to the base of the wall to properly attach and lap the flashing. In this strategy, R-7.5, 1.5-in.-thick extruded polystyrene was installed on the exterior of the slab for a modeled savings of 4,500 Btu/h on the heating load.« less

New Whole-House Solutions Case Study: Exterior Rigid Foam Insulation at the Edge of a Slab Foundation, Fresno, California

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

Exterior rigid foam insulation at the edge of the slab foundation was a unique feature for this low-load, unoccupied test house in a hot-dry climate and may be more appropriate for climates with higher heating loads. U.S. Department of Energy Building America research team IBACOS worked with National Housing Quality Award winner Wathen-Castanos Hybrid Homes, Inc., to assess the performance of this feature in a single-family detached ranch house with three bedrooms and two full bathrooms constructed on a slab-on-grade foundation in Fresno, California. One challenge during installation of the system was the attachment of the butyl flashing to themore » open framing. To solve this constructability issue, the team added a nailer to the base of the wall to properly attach and lap the flashing. In this strategy, R-7.5, 1.5-in.-thick extruded polystyrene was installed on the exterior of the slab for a modeled savings of 4,500 Btu/h on the heating load.« less

Highway deicing salt dynamic runoff to surface water and subsequent infiltration to groundwater during severe UK winters.

PubMed

Rivett, Michael O; Cuthbert, Mark O; Gamble, Richard; Connon, Lucy E; Pearson, Andrew; Shepley, Martin G; Davis, John

2016-09-15

Dynamic impact to the water environment of deicing salt application at a major highway (motorway) interchange in the UK is quantitatively evaluated for two recent severe UK winters. The contaminant transport pathway studied allowed controls on dynamic highway runoff and storm-sewer discharge to a receiving stream and its subsequent leakage to an underlying sandstone aquifer, including possible contribution to long-term chloride increases in supply wells, to be evaluated. Logged stream electrical-conductivity (EC) to estimate chloride concentrations, stream flow, climate and motorway salt application data were used to assess salt fate. Stream loading was responsive to salt applications and climate variability influencing salt release. Chloride (via EC) was predicted to exceed the stream Environmental Quality Standard (250mg/l) for 33% and 18% of the two winters. Maximum stream concentrations (3500mg/l, 15% sea water salinity) were ascribed to salt-induced melting and drainage of highway snowfall without dilution from, still frozen, catchment water. Salt persistance on the highway under dry-cold conditions was inferred from stream observations of delayed salt removal. Streambed and stream-loss data demonstrated chloride infiltration could occur to the underlying aquifer with mild and severe winter stream leakage estimated to account for 21 to 54% respectively of the 70t of increased chloride (over baseline) annually abstracted by supply wells. Deicing salt infiltration lateral to the highway alongside other urban/natural sources were inferred to contribute the shortfall. Challenges in quantifying chloride mass/fluxes (flow gauge accuracy at high flows, salt loading from other roads, weaker chloride-EC correlation at low concentrations), may be largely overcome by modest investment in enhanced data acquisition or minor approach modification. The increased understanding of deicing salt dynamic loading to the water environment obtained is relevant to improved groundwater resource management, highway salt application practice, surface-water - ecosystem management, and decision making on highway drainage to ground. Copyright © 2016 Elsevier B.V. All rights reserved.

Association between meteorological factors and bacillary dysentery incidence in Chaoyang city, China: an ecological study.

PubMed

Zhao, Yang; Zhu, Yaxin; Zhu, Zhiwei; Qu, Bo

2016-12-09

To quantify the relationship between meteorological factors and bacillary dysentery incidence. Ecological study. We collected bacillary dysentery incidences and meteorological data of Chaoyang city from the year 1981 to 2010. The climate in this city was a typical northern temperate continental monsoon. All meteorological factors in this study were divided into 4 latent factors: temperature, humidity, sunshine and airflow. Structural equation modelling was used to analyse the relationship between meteorological factors and the incidence of bacillary dysentery. Incidences of bacillary dysentery were obtained from the Center for Disease Control and Prevention of Chaoyang city, and meteorological data were collected from the Bureau of Meteorology in Chaoyang city. The indexes including χ 2 , root mean square error of approximation (RMSEA), comparative fit index (CFI), standardised root mean square residual (SRMR) and goodness-of-fit index (GFI) were used to evaluate the goodness-of-fit of the theoretical model to the data. The factor loads were used to explore quantitative relationship between bacillary dysentery incidences and meteorological factors. The goodness-of-fit results of the model showing that RMSEA=0.08, GFI=0.84, CFI=0.88, SRMR=0.06 and the χ 2 value is 231.95 (p=0.0) with 15 degrees of freedom. Temperature and humidity factors had positive correlations with incidence of bacillary dysentery, with the factor load of 0.59 and 0.78, respectively. Sunshine had a negative correlation with bacillary dysentery incidence, with a factor load of -0.15. Humidity and temperature should be given greater consideration in bacillary dysentery prevention measures for northern temperate continental monsoon climates, such as that of Chaoyang. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

Reservoir Sedimentation and Upstream Sediment Sources: Perspectives and Future Research Needs on Streambank and Gully Erosion.

PubMed

Fox, G A; Sheshukov, A; Cruse, R; Kolar, R L; Guertault, L; Gesch, K R; Dutnell, R C

2016-05-01

The future reliance on water supply and flood control reservoirs across the globe will continue to expand, especially under a variable climate. As the inventory of new potential dam sites is shrinking, construction of additional reservoirs is less likely compared to simultaneous flow and sediment management in existing reservoirs. One aspect of this sediment management is related to the control of upstream sediment sources. However, key research questions remain regarding upstream sediment loading rates. Highlighted in this article are research needs relative to measuring and predicting sediment transport rates and loading due to streambank and gully erosion within a watershed. For example, additional instream sediment transport and reservoir sedimentation rate measurements are needed across a range of watershed conditions, reservoir sizes, and geographical locations. More research is needed to understand the intricate linkage between upland practices and instream response. A need still exists to clarify the benefit of restoration or stabilization of a small reach within a channel system or maturing gully on total watershed sediment load. We need to better understand the intricate interactions between hydrological and erosion processes to improve prediction, location, and timing of streambank erosion and failure and gully formation. Also, improved process-based measurement and prediction techniques are needed that balance data requirements regarding cohesive soil erodibility and stability as compared to simpler topographic indices for gullies or stream classification systems. Such techniques will allow the research community to address the benefit of various conservation and/or stabilization practices at targeted locations within watersheds.

Reservoir Sedimentation and Upstream Sediment Sources: Perspectives and Future Research Needs on Streambank and Gully Erosion

NASA Astrophysics Data System (ADS)

Fox, G. A.; Sheshukov, A.; Cruse, R.; Kolar, R. L.; Guertault, L.; Gesch, K. R.; Dutnell, R. C.

2016-05-01

The future reliance on water supply and flood control reservoirs across the globe will continue to expand, especially under a variable climate. As the inventory of new potential dam sites is shrinking, construction of additional reservoirs is less likely compared to simultaneous flow and sediment management in existing reservoirs. One aspect of this sediment management is related to the control of upstream sediment sources. However, key research questions remain regarding upstream sediment loading rates. Highlighted in this article are research needs relative to measuring and predicting sediment transport rates and loading due to streambank and gully erosion within a watershed. For example, additional instream sediment transport and reservoir sedimentation rate measurements are needed across a range of watershed conditions, reservoir sizes, and geographical locations. More research is needed to understand the intricate linkage between upland practices and instream response. A need still exists to clarify the benefit of restoration or stabilization of a small reach within a channel system or maturing gully on total watershed sediment load. We need to better understand the intricate interactions between hydrological and erosion processes to improve prediction, location, and timing of streambank erosion and failure and gully formation. Also, improved process-based measurement and prediction techniques are needed that balance data requirements regarding cohesive soil erodibility and stability as compared to simpler topographic indices for gullies or stream classification systems. Such techniques will allow the research community to address the benefit of various conservation and/or stabilization practices at targeted locations within watersheds.

Removal of Organic Pollutants from Municipal Wastewater by Applying High-Rate Algal Pond in Addis Ababa, Ethiopia

NASA Astrophysics Data System (ADS)

Alemu, Keneni; Assefa, Berhanu; Kifle, Demeke; Kloos, Helmut

2018-05-01

The discharge of inadequately treated municipal wastewater has aggravated the pollution load in developing countries including Ethiopia. Conventional wastewater treatment methods that require high capital and operational costs are not affordable for many developing nations, including Ethiopia. This study aimed to investigate the performance of two high-rate algal ponds (HRAPs) in organic pollutant removal from primary settled municipal wastewater under highland tropical climate conditions in Addis Ababa. The experiment was done for 2 months at hydraulic retention times (HRTs) ranging from 2 to 8 days using an organic loading rates ranging 333-65 kg {BOD}5 /ha/day using two HRAPs, 250 and 300 mm deep, respectively. In this experiment, Chlorella sp., Chlamydomonas sp., and Scenedesmus sp., the class of Chlorophyceae, were identified as the dominant species. Chlorophyll-a production was higher in the shallower ponds (250 mm) throughout the course of the study, whereas the deeper HRAP (300 mm) showed better dissolved oxygen production. The maximum COD and {BOD}5 removal of 78.03 and 81.8% was achieved at a 6-day HRT operation in the 250-mm-deep HRAP. Therefore, the 300-mm-deep HRAP is promising for scaling up organic pollutant removal from municipal wastewater at a daily average organic loading rate of 109.3 kg {BOD}5 /ha/day and a 6-day HRT. We conclude that the removal of organic pollutants in HRAP can be controlled by pond depth, organic loading rate, and HRT.

Thermal dynamic simulation of wall for building energy efficiency under varied climate environment

NASA Astrophysics Data System (ADS)

Wang, Xuejin; Zhang, Yujin; Hong, Jing

2017-08-01

Aiming at different kind of walls in five cities of different zoning for thermal design, using thermal instantaneous response factors method, the author develops software to calculation air conditioning cooling load temperature, thermal response factors, and periodic response factors. On the basis of the data, the author gives the net work analysis about the influence of dynamic thermal of wall on air-conditioning load and thermal environment in building of different zoning for thermal design regional, and put forward the strategy how to design thermal insulation and heat preservation wall base on dynamic thermal characteristic of wall under different zoning for thermal design regional. And then provide the theory basis and the technical references for the further study on the heat preservation with the insulation are in the service of energy saving wall design. All-year thermal dynamic load simulating and energy consumption analysis for new energy-saving building is very important in building environment. This software will provide the referable scientific foundation for all-year new thermal dynamic load simulation, energy consumption analysis, building environment systems control, carrying through farther research on thermal particularity and general particularity evaluation for new energy -saving walls building. Based on which, we will not only expediently design system of building energy, but also analyze building energy consumption and carry through scientific energy management. The study will provide the referable scientific foundation for carrying through farther research on thermal particularity and general particularity evaluation for new energy saving walls building.

How the National Estuary Programs Address Environmental Issues

EPA Pesticide Factsheets

Estuaries face many challenges including, alteration of natural hydrologic flows, aquatic nuisance species, climate change, declines in fish and wildlife populations, habitat loss and degradation, nutrient loads, pathogens, stormwater and toxics.

Multiple effects and uncertainties of emission control policies in China: Implications for public health, soil acidification, and global temperature.

PubMed

Zhao, Yu; McElroy, Michael B; Xing, Jia; Duan, Lei; Nielsen, Chris P; Lei, Yu; Hao, Jiming

2011-11-15

Policies to control emissions of criteria pollutants in China may have conflicting impacts on public health, soil acidification, and climate. Two scenarios for 2020, a base case without anticipated control measures and a more realistic case including such controls, are evaluated to quantify the effects of the policies on emissions and resulting environmental outcomes. Large benefits to public health can be expected from the controls, attributed mainly to reduced emissions of primary PM and gaseous PM precursors, and thus lower ambient concentrations of PM2.5. Approximately 4% of all-cause mortality in the country can be avoided (95% confidence interval: 1-7%), particularly in eastern and north-central China, regions with large population densities and high levels of PM2.5. Surface ozone levels, however, are estimated to increase in parts of those regions, despite NOX reductions. This implies VOC-limited conditions. Even with significant reduction of SO2 and NOX emissions, the controls will not significantly mitigate risks of soil acidification, judged by the exceedance levels of critical load (CL). This is due to the decrease in primary PM emissions, with the consequent reduction in deposition of alkaline base cations. Compared to 2005, even larger CL exceedances are found for both scenarios in 2020, implying that PM control may negate any recovery from soil acidification due to SO2 reductions. Noting large uncertainties, current polices to control emissions of criteria pollutants in China will not reduce climate warming, since controlling SO2 emissions also reduces reflective secondary aerosols. Black carbon emission is an important source of uncertainty concerning the effects of Chinese control policies on global temperature change. Given these conflicts, greater consideration should be paid to reconciling varied environmental objectives, and emission control strategies should target not only criteria pollutants but also species such as VOCs and CO2. Copyright © 2011 Elsevier B.V. All rights reserved.

Development of Smart Ventilation Control Algorithms for Humidity Control in High-Performance Homes in Humid U.S. Climates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Less, Brennan; Walker, Iain; Ticci, Sara

Past field research and simulation studies have shown that high performance homes experience elevated indoor humidity levels for substantial portions of the year in humid climates. This is largely the result of lower sensible cooling loads, which reduces the moisture removed by the cooling system. These elevated humidity levels lead to concerns about occupant comfort, health and building durability. Use of mechanical ventilation at rates specified in ASHRAE Standard 62.2-2013 are often cited as an additional contributor to humidity problems in these homes. Past research has explored solutions, including supplemental dehumidification, cooling system operational enhancements and ventilation system design (e.g.,more » ERV, supply, exhaust, etc.). This project’s goal is to develop and demonstrate (through simulations) smart ventilation strategies that can contribute to humidity control in high performance homes. These strategies must maintain IAQ via equivalence with ASHRAE Standard 62.2-2013. To be acceptable they must not result in excessive energy use. Smart controls will be compared with dehumidifier energy and moisture performance. This work explores the development and performance of smart algorithms for control of mechanical ventilation systems, with the objective of reducing high humidity in modern high performance residences. Simulations of DOE Zero-Energy Ready homes were performed using the REGCAP simulation tool. Control strategies were developed and tested using the Residential Integrated Ventilation (RIVEC) controller, which tracks pollutant exposure in real-time and controls ventilation to provide an equivalent exposure on an annual basis to homes meeting ASHRAE 62.2-2013. RIVEC is used to increase or decrease the real-time ventilation rate to reduce moisture transport into the home or increase moisture removal. This approach was implemented for no-, one- and two-sensor strategies, paired with a variety of control approaches in six humid climates (Miami, Orlando, Houston, Charleston, Memphis and Baltimore). The control options were compared to a baseline system that supplies outdoor air to a central forced air cooling (and heating) system (CFIS) that is often used in hot humid climates. Simulations were performed with CFIS ventilation systems operating on a 33% duty-cycle, consistent with 62.2-2013. The CFIS outside airflow rates were set to 0%, 50% and 100% of 62.2-2013 requirements to explore effects of ventilation rate on indoor high humidity. These simulations were performed with and without a dehumidifier in the model. Ten control algorithms were developed and tested. Analysis of outdoor humidity patterns facilitated smart control development. It was found that outdoor humidity varies most strongly seasonally—by month of the year—and that all locations follow the similar pattern of much higher humidity during summer. Daily and hourly variations in outdoor humidity were found to be progressively smaller than the monthly seasonal variation. Patterns in hourly humidity are driven by diurnal daily patterns, so they were predictable but small, and were unlikely to provide much control benefit. Variation in outdoor humidity between days was larger, but unpredictable, except by much more complex climate models. We determined that no-sensor strategies might be able to take advantage of seasonal patterns in humidity, but that real-time smart controls were required to capture variation between days. Sensor-based approaches are also required to respond dynamically to indoor conditions and variations not considered in our analysis. All smart controls face trade-offs between sensor accuracy, cost, complexity and robustness.« less

Design Calculation Procedure for Passive Solar Houses at Navy Installations in Regions with Warm, Humid Climate. Volume III.

DTIC Science & Technology

1981-10-01

and Storage Locations . ... 7 2.3 Heat Transfer Mechanisms of Thermal Storage Walls ...... ... 11 2.4 Heating of Living Space with Solar Greenhouse ...12 2.5 Schematic of North-Side Greenhouse Retrofit .... ......... 12 2.6 The Roof Pond in Warm Climate ................... ... 14 2.7...Building Thermal Load Profile ... ........ 48 5 Calculation of Solar Heating Contribution ............. 52 5A Adjusted Net Solar Greenhouse Heat Gain

NASA Products to Enhance Energy Utility Load Forecasting

NASA Technical Reports Server (NTRS)

Lough, G.; Zell, E.; Engel-Cox, J.; Fungard, Y.; Jedlovec, G.; Stackhouse, P.; Homer, R.; Biley, S.

2012-01-01

Existing energy load forecasting tools rely upon historical load and forecasted weather to predict load within energy company service areas. The shortcomings of load forecasts are often the result of weather forecasts that are not at a fine enough spatial or temporal resolution to capture local-scale weather events. This project aims to improve the performance of load forecasting tools through the integration of high-resolution, weather-related NASA Earth Science Data, such as temperature, relative humidity, and wind speed. Three companies are participating in operational testing one natural gas company, and two electric providers. Operational results comparing load forecasts with and without NASA weather forecasts have been generated since March 2010. We have worked with end users at the three companies to refine selection of weather forecast information and optimize load forecast model performance. The project will conclude in 2012 with transitioning documented improvements from the inclusion of NASA forecasts for sustained use by energy utilities nationwide in a variety of load forecasting tools. In addition, Battelle has consulted with energy companies nationwide to document their information needs for long-term planning, in light of climate change and regulatory impacts.

Systems and methods for providing power to a load based upon a control strategy

DOEpatents

Perisic, Milun; Kajouke, Lateef A; Ransom, Ray M

2013-12-24

Systems and methods are provided for an electrical system. The electrical system includes a load, an interface configured to receive a voltage from a voltage source, and a controller configured to receive the voltage from the voltage source through the interface and to provide a voltage and current to the load. Wherein, when the controller is in a constant voltage mode, the controller provides a constant voltage to the load, when the controller is in a constant current mode, the controller provides a constant current to the load, and when the controller is in a constant power mode, the controller provides a constant power to the load.

Minimal climate change impacts on natural organic matter forecasted for a potable water supply in Ireland.

PubMed

O'Driscoll, Connie; Ledesma, José L J; Coll, John; Murnane, John G; Nolan, Paul; Mockler, Eva M; Futter, Martyn N; Xiao, Liwen W

2018-07-15

Natural organic matter poses an increasing challenge to water managers because of its potential adverse impacts on water treatment and distribution, and subsequently human health. Projections were made of impacts of climate change on dissolved organic carbon (DOC) in the primarily agricultural Boyne catchment which is used as a potable water supply in Ireland. The results indicated that excluding a potential rise in extreme precipitation, future projected loads are not dissimilar to those observed under current conditions. This is because projected increases in DOC concentrations are offset by corresponding decreases in precipitation and hence river flow. However, the results presented assume no changes in land use and highlight the predicted increase in DOC loads from abstracted waters at water treatment plants. Copyright © 2018. Published by Elsevier B.V.

Response of Colorado river runoff to dust radiative forcing in snow

USGS Publications Warehouse

Painter, T.H.; Deems, J.S.; Belnap, J.; Hamlet, A.F.; Landry, C.C.; Udall, B.

2010-01-01

The waters of the Colorado River serve 27 million people in seven states and two countries but are overallocated by more than 10% of the river's historical mean. Climate models project runoff losses of 7-20% from the basin in this century due to human-induced climate change. Recent work has shown however that by the late 1800s, decades prior to allocation of the river's runoff in the 1920s, a fivefold increase in dust loading from anthropogenically disturbed soils in the southwest United States was already decreasing snow albedo and shortening the duration of snow cover by several weeks. The degree to which this increase in radiative forcing by dust in snow has affected timing and magnitude of runoff from the Upper Colorado River Basin (UCRB) is unknown. Hereweuse the Variable Infiltration Capacity model with postdisturbance and predisturbance impacts of dust on albedo to estimate the impact on runoff from the UCRB across 1916-2003. We find that peak runoff at Lees Ferry, Arizona has occurred on average 3 wk earlier under heavier dust loading and that increases in evapotranspiration from earlier exposure of vegetation and soils decreases annual runoff by more than 1.0 billion cubic meters or ???5% of the annual average. The potential to reduce dust loading through surface stabilization in the deserts and restore more persistent snow cover, slow runoff, and increase water resources in the UCRB may represent an important mitigation opportunity to reduce system management tensions and regional impacts of climate change.

Field Investigation of an Air-Source Cold Climate Heat Pump

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shen, Bo; Abdelaziz, Omar; Rice, C Keith

In the U.S., there are approximately 2.6 million dwellings that use electricity for heating in cold and very cold regions with an annual energy consumption of 0.16 quads (0.17 EJ). A high performance cold climate heat pump (CCHP) would result in significant savings over current technologies (greater than 60% compared to electric resistance heating). We developed an air-source cold climate heat pump, which uses tandem compressors, with a single compressor rated for the building design cooling load, and running two compressors to provide, at -13 F (-25 C), 75% of rated heating capacity. The tandem compressors were optimized for heatingmore » operation and are able to tolerate discharge temperatures up to 280 F (138 C). A field investigation was conducted in the winter of 2015, in an occupied home in Ohio, USA. During the heating season, the seasonal COP was measured at 3.16, and the heat pump was able to operate down to -13 F (-25 C) and eliminate resistance heat use. The heat pump maintained an acceptable comfort level throughout the heating season. In comparison to a previous single-speed heat pump in the home, the CCHP demonstrated more than 40% energy savings in the peak heating load month. This paper illustrates the measured field performance, including compressor run time, frost/defrosting operations, distributions of building heating load and capacity delivery, comfort level, field measured COPs, etc.« less

Management of Local Stressors Can Improve the Resilience of Marine Canopy Algae to Global Stressors

PubMed Central

Strain, Elisabeth M. A.; van Belzen, Jim; van Dalen, Jeroen; Bouma, Tjeerd J.; Airoldi, Laura

2015-01-01

Coastal systems are increasingly threatened by multiple local anthropogenic and global climatic stressors. With the difficulties in remediating global stressors, management requires alternative approaches that focus on local scales. We used manipulative experiments to test whether reducing local stressors (sediment load and nutrient concentrations) can improve the resilience of foundation species (canopy algae along temperate rocky coastlines) to future projected global climate stressors (high wave exposure, increasing sea surface temperature), which are less amenable to management actions. We focused on Fucoids (Cystoseira barbata) along the north-western Adriatic coast in the Mediterranean Sea because of their ecological relevance, sensitivity to a variety of human impacts, and declared conservation priority. At current levels of sediment and nutrients, C. barbata showed negative responses to the simulated future scenarios of high wave exposure and increased sea surface temperature. However, reducing the sediment load increased the survival of C. barbata recruits by 90.24% at high wave exposure while reducing nutrient concentrations resulted in a 20.14% increase in the survival and enhanced the growth of recruited juveniles at high temperature. We conclude that improving water quality by reducing nutrient concentrations, and particularly the sediment load, would significantly increase the resilience of C. barbata populations to projected increases in climate stressors. Developing and applying appropriate targets for specific local anthropogenic stressors could be an effective management action to halt the severe and ongoing loss of key marine habitats. PMID:25807516

Establishing an Ongoing Binational U.S.-Mexico Border Climate Diagnostic Summary: Developing a Prototype and Navigating the Institutional Landscape

NASA Astrophysics Data System (ADS)

Garfin, G.; Varady, R.; Morehouse, B.; Wilder, M.; Crawford, B.

2007-05-01

In its eighth report to the President and Congress of the United States, the Good Neighbor Environmental Board (an independent federal advisory committee, that advises the President and Congress on environmental practices and infrastructure needs along the U.S. border with Mexico) noted that management of water resources issues along the U.S. border with Mexico would be aided by data and information sharing. They encouraged agencies and institutions to make data accessible, and to exchange data and information, even on a limited or ad hoc basis, in order to build trust and the capacity for managers and staff on both sides of the border to collaborate and work together to solve problems of mutual interest. Although climate is merely one factor affecting decision makers, it can often be the "straw that breaks the camel's back." Along the arid and semiarid U.S. border with Mexico, population growth, industrialization, increasing water consumption, and other factors have exacerbated societal vulnerability to naturally occurring persistent climate phenomena, such as drought. In 2006, scientists from institutions in the U.S. and Mexico agreed to collaborate to address decision makers' pressing needs for climate information, by developing a climate diagnostic and outlook product in a format usable and easily accessible by managers and policy makers. The Border Climate Summary (Resumen del Climate de la Frontera), modeled after monthly climate newsletters produced in the U.S., provides a tangible and simple information tool to strengthen the basic capacity for climate information to be usefully incorporated into decision processes. The Summary provides forecasts and value-added information on temperature, precipitation, and drought within the region. However, in order for the Summary to be effective at reaching its intended audiences, collaborators must break through barriers posed by regulatory and institutional control. They must also identify key insertion points for climate information or risk that the product of their efforts will end up as another seldom used box of digital information merchandise heaped on the loading dock of the Internet. This presentation describes progress to date in developing a collaborative, binational semi-operational product, obtaining funding, and taking the first steps to establish regional climate services for the U.S.-Mexico border region.

Robust Decision Making to Support Water Quality Climate Adaptation: a Case Study in the Chesapeake Bay Watershed

NASA Astrophysics Data System (ADS)

Fischbach, J. R.; Lempert, R. J.; Molina-Perez, E.

2017-12-01

The U.S. Environmental Protection Agency (USEPA), together with state and local partners, develops watershed implementation plans designed to meet water quality standards. Climate uncertainty, along with uncertainty about future land use changes or the performance of water quality best management practices (BMPs), may make it difficult for these implementation plans to meet water quality goals. In this effort, we explored how decision making under deep uncertainty (DMDU) methods such as Robust Decision Making (RDM) could help USEPA and its partners develop implementation plans that are more robust to future uncertainty. The study focuses on one part of the Chesapeake Bay watershed, the Patuxent River, which is 2,479 sq km in area, highly urbanized, and has a rapidly growing population. We simulated the contribution of stormwater contaminants from the Patuxent to the overall Total Maximum Daily Load (TMDL) for the Chesapeake Bay under multiple scenarios reflecting climate and other uncertainties. Contaminants considered included nitrogen, phosphorus, and sediment loads. The assessment included a large set of scenario simulations using the USEPA Chesapeake Bay Program's Phase V watershed model. Uncertainties represented in the analysis included 18 downscaled climate projections (based on 6 general circulation models and 3 emissions pathways), 12 land use scenarios with different population projections and development patterns, and alternative assumptions about BMP performance standards and efficiencies associated with different suites of stormwater BMPs. Finally, we developed cost estimates for each of the performance standards and compared cost to TMDL performance as a key tradeoff for future water quality management decisions. In this talk, we describe how this research can help inform climate-related decision support at USEPA's Chesapeake Bay Program, and more generally how RDM and other DMDU methods can support improved water quality management under climate uncertainty.

Effect of climate change on stormwater runoff characteristics and treatment efficiencies of stormwater retention ponds: a case study from Denmark using TSS and Cu as indicator pollutants.

PubMed

Sharma, Anitha Kumari; Vezzaro, Luca; Birch, Heidi; Arnbjerg-Nielsen, Karsten; Mikkelsen, Peter Steen

2016-01-01

This study investigated the potential effect of climate changes on stormwater pollution runoff characteristics and the treatment efficiency of a stormwater retention pond in a 95 ha catchment in Denmark. An integrated dynamic stormwater runoff quality and treatment model was used to simulate two scenarios: one representing the current climate and another representing a future climate scenario with increased intensity of extreme rainfall events and longer dry weather periods. 100-year long high-resolution rainfall time series downscaled from regional climate model projections were used as input. The collected data showed that total suspended solids (TSS) and total copper (Cu) concentrations in stormwater runoff were related to flow, rainfall intensity and antecedent dry period. Extreme peak intensities resulted in high particulate concentrations and high loads but did not affect dissolved Cu concentrations. The future climate simulations showed an increased frequency of higher flows and increased total concentrations discharged from the catchment. The effect on the outlet from the pond was an increase in the total concentrations (TSS and Cu), whereas no major effect was observed on dissolved Cu concentrations. Similar results are expected for other particle bound pollutants including metals and slowly biodegradable organic substances such as PAH. Acute toxicity impacts to downstream surface waters seem to be only slightly affected. A minor increase in yearly loads of sediments and particle-bound pollutants is expected, mainly caused by large events disrupting the settling process. This may be important to consider for the many stormwater retention ponds existing in Denmark and across the world.

Rainfall, runoff and sediment transport in a Mediterranean mountainous catchment.

PubMed

Tuset, J; Vericat, D; Batalla, R J

2016-01-01

The relation between rainfall, runoff, erosion and sediment transport is highly variable in Mediterranean catchments. Their relation can be modified by land use changes and climate oscillations that, ultimately, will control water and sediment yields. This paper analyses rainfall, runoff and sediment transport relations in a meso-scale Mediterranean mountain catchment, the Ribera Salada (NE Iberian Peninsula). A total of 73 floods recorded between November 2005 and November 2008 at the Inglabaga Sediment Transport Station (114.5 km(2)) have been analysed. Suspended sediment transport and flow discharge were measured continuously. Rainfall data was obtained by means of direct rain gauges and daily rainfall reconstructions from radar information. Results indicate that the annual sediment yield (2.3 t km(-1) y(-1) on average) and the flood-based runoff coefficients (4.1% on average) are low. The Ribera Salada presents a low geomorphological and hydrological activity compared with other Mediterranean mountain catchments. Pearson correlations between rainfall, runoff and sediment transport variables were obtained. The hydrological response of the catchment is controlled by the base flows. The magnitude of suspended sediment concentrations is largely correlated with flood magnitude, while sediment load is correlated with the amount of direct runoff. Multivariate analysis shows that total suspended load can be predicted by integrating rainfall and runoff variables. The total direct runoff is the variable with more weight in the equation. Finally, three main hydro-sedimentary phases within the hydrological year are defined in this catchment: (a) Winter, where the catchment produces only water and very little sediment; (b) Spring, where the majority of water and sediment is produced; and (c) Summer-Autumn, when little runoff is produced but significant amount of sediments is exported out of the catchment. Results show as land use and climate change may have an important role in modifying the cycles of water and sediment yields in Mediterranean mountain catchments. Copyright © 2015 Elsevier B.V. All rights reserved.

Quantification of BMPs Selection and Spatial Placement Impact on Water Quality Controlling Plans in Lower Bear River Watershed, Utah

NASA Astrophysics Data System (ADS)

Salha, A. A.; Stevens, D. K.

2016-12-01

The aim of the watershed-management program in Box Elder County, Utah set by Utah Division of Water Quality (UDEQ) is to evaluate the effectiveness and spatial placement of the implemented best-management practices (BMP) for controlling nonpoint-source contamination at watershed scale. The need to evaluate the performance of BMPs would help future policy and program decisions making as desired end results. The environmental and costs benefits of BMPs in Lower Bear River watershed have seldom been measured beyond field experiments. Yet, implemented practices have rarely been evaluated at the watershed scale where the combined effects of variable soils, climatic conditions, topography and land use/covers and management conditions may significantly change anticipated results and reductions loads. Such evaluation requires distributed watershed models that are necessary for quantifying and reproducing the movement of water, sediments and nutrients. Soil and Water Assessment Tool (SWAT) model is selected as a watershed level tool to identify contaminant nonpoint sources (critical zones) and areas of high pollution risks. Water quality concerns have been documented and are primarily attributed to high phosphorus and total suspended sediment concentrations caused by agricultural and farming practices (required load is 460 kg/day of total phosphorus based on 0.075 mg/l and an average of total suspended solids of 90 mg/l). Input data such as digital elevation model (DEM), land use/Land cover (LULC), soils, and climate data for 10 years (2000-2010) is utilized along with observed water quality at the watershed outlet (USGS) and some discrete monitoring points within the watershed. Statistical and spatial analysis of scenarios of management practices (BMP's) are not implemented (before implementation), during implementation, and after BMP's have been studied to determine whether water quality of the two main water bodies has improved as required by the LBMR watershed's TMDL and if the BMPs are cost-effectively targeting the critical zones.

Comparative study of transport processes of nitrogen, phosphorus, and herbicides to streams in five agricultural basins, USA

USGS Publications Warehouse

Domagalski, Joseph L.; Ator, S.; Coupe, R.; McCarthy, K.; Lampe, D.; Sandstrom, M.; Baker, N.

2008-01-01

Agricultural chemical transport to surface water and the linkage to other hydrological compartments, principally ground water, was investigated at five watersheds in semiarid to humid climatic settings. Chemical transport was affected by storm water runoff, soil drainage, irrigation, and how streams were linked to shallow ground water systems. Irrigation practices and timing of chemical use greatly affected nutrient and pesticide transport in the semiarid basins. Irrigation with imported water tended to increase ground water and chemical transport, whereas the use of locally pumped irrigation water may eliminate connections between streams and ground water, resulting in lower annual loads. Drainage pathways in humid environments are important because the loads may be transported in tile drains, or through varying combinations of ground water discharge, and overland flow. In most cases, overland flow contributed the greatest loads, but a significant portion of the annual load of nitrate and some pesticide degradates can be transported under base-flow conditions. The highest basin yields for nitrate were measured in a semiarid irrigated system that used imported water and in a stream dominated by tile drainage in a humid environment. Pesticide loads, as a percent of actual use (LAPU), showed the effects of climate and geohydrologic conditions. The LAPU values in the semiarid study basin in Washington were generally low because most of the load was transported in ground water discharge to the stream. When herbicides are applied during the rainy season in a semiarid setting, such as simazine in the California basin, LAPU values are similar to those in the Midwest basins. Copyright ?? 2008 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. All rights reserved.

Climate and on-farm risk factors associated with Giardia duodenalis cysts in storm runoff from California coastal dairies.

PubMed

Miller, Woutrina A; Lewis, David J; Lennox, Michael; Pereira, Maria G C; Tate, Kenneth W; Conrad, Patricia A; Atwill, Edward R

2007-11-01

Climatic factors and on-farm management practices were evaluated for their association with the concentrations (cyst/liter) and instantaneous loads (cysts/second) of Giardia duodenalis in storm-based runoff from dairy lots and other high-cattle-use areas on five coastal California farms over two storm seasons. Direct fluorescent antibody analysis was used to quantitate cysts in 350 storm runoff samples. G. duodenalis was detected on all five dairy farms, with fluxes of 1 to 14,000 cysts/liter observed in 16% of samples. Cysts were detected in 41% of runoff samples collected near cattle less than 2 months old, compared to 10% of runoff samples collected near cattle over 6 months old. Furthermore, the concentrations and instantaneous loads of cysts were > or =65 and > or =79 times greater, respectively, in runoff from sites housing young calves than in sites housing other age classes of animals. Factors associated with environmental loading of G. duodenalis included cattle age, cattle stocking number, and precipitation but not lot area, land slope, or cattle density. Vegetated buffer strips were found to significantly reduce waterborne cysts in storm runoff: each additional meter of vegetated buffer placed below high-cattle-use areas was associated with reductions in the concentration and instantaneous load of cysts by factors of 0.86 and 0.79 (-0.07 and -0.10 log(10)/m), respectively. Straw mulch, seed application, scraping of manure, and cattle exclusion did not significantly affect the concentration or load of G. duodenalis cysts. The study findings suggest that vegetated buffer strips, especially when placed near dairy calf areas, should help reduce the environmental loading of these fecal protozoa discharging from dairy farms.

Energy performance and savings potentials with skylights

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arasteh, D.; Johnson, R.; Selkowitz, S.

1984-12-01

This study systematically explores the energy effects of skylight systems in a prototypical office building module and examines the savings from daylighting. For specific climates, roof/skylight characteristics are identified that minimize total energy or peak electrical demand. Simplified techniques for energy performance calculation are also presented based on a multiple regression analysis of our data base so that one may easily evaluate daylighting's effects on total and component energy loads and electrical peaks. This provides additional insights into the influence of skylight parameters on energy consumption and electrical peaks. We use the DOE-2.1B energy analysis program with newly incorporated daylightingmore » algorithms to determine hourly, monthly, and annual impacts of daylighting strategies on electrical lighting consumption, cooling, heating, fan power, peak electrical demands, and total energy use. A data base of more than 2000 parametric simulations for 14 US climates has been generated. Parameters varied include skylight-to-roof ratio, shading coefficient, visible transmittance, skylight well light loss, electric lighting power density, roof heat transfer coefficient, and electric lighting control type. 14 references, 13 figures, 4 tables.« less

A conduit dilation model of methane venting from lake sediments

USGS Publications Warehouse

Scandella, B.P.; Varadharajan, C.; Hemond, Harold F.; Ruppel, C.; Juanes, R.

2011-01-01

Methane is a potent greenhouse gas, but its effects on Earth's climate remain poorly constrained, in part due to uncertainties in global methane fluxes to the atmosphere. An important source of atmospheric methane is the methane generated in organic-rich sediments underlying surface water bodies, including lakes, wetlands, and the ocean. The fraction of the methane that reaches the atmosphere depends critically on the mode and spatiotemporal characteristics of free-gas venting from the underlying sediments. Here we propose that methane transport in lake sediments is controlled by dynamic conduits, which dilate and release gas as the falling hydrostatic pressure reduces the effective stress below the tensile strength of the sediments. We test our model against a four-month record of hydrostatic load and methane flux in Upper Mystic Lake, Mass., USA, and show that it captures the complex episodicity of methane ebullition. Our quantitative conceptualization opens the door to integrated modeling of methane transport to constrain global methane release from lakes and other shallow-water, organic-rich sediment systems, and to assess its climate feedbacks.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

This report, Evaluation of the Performance of Houses with and without Supplemental Dehumidification in a Hot-Humid Climate, describes a research study that that was conducted by the Building Science Corporation (BSC) Building America Research Team. BSC seeks to research and report on the field monitoring of the performance of in-situ supplemental dehumidification systems in low energy, high performance, homes in a Hot-Humid climate. The purpose of this research project was to observe and compare the humidity control performance of new, single family, low energy, and high performance, homes. Specifically, the study sought to compare the interior conditions and mechanical systemsmore » operation between two distinct groups of houses, homes with a supplemental dehumidifier installed in addition to HVAC system, and homes without any supplemental dehumidification. The subjects of the study were ten single-family new construction homes in New Orleans, LA. Data logging equipment was installed at each home in 2012. Interior conditions and various end-use loads were monitored for one year. In terms of averages, the homes with dehumidifiers are limiting elevated levels of humidity in the living space. However, there was significant variation in humidity control between individual houses. An analysis of the equipment operation did not show a clear correlation between energy use and humidity levels. In general, no single explanatory variable appears to provide a consistent understanding of the humidity control in each house. Indoor humidity is likely due to all of the factors we have examined, and the specifics of how they are used by each occupant.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kerrigan, P.; Norton, P.

This report, Evaluation of the Performance of Houses with and without Supplemental Dehumidification in a Hot-Humid Climate, describes a research study that that was conducted by the Building Science Corporation (BSC) Building America Research Team. BSC seeks to research and report on the field monitoring of the performance of in-situ supplemental dehumidification systems in low energy, high performance, homes in a Hot-Humid climate. The purpose of this research project was to observe and compare the humidity control performance of new, single family, low energy, and high performance, homes. Specifically, the study sought to compare the interior conditions and mechanical systemsmore » operation between two distinct groups of houses, homes with a supplemental dehumidifier installed in addition to HVAC system, and homes without any supplemental dehumidification. The subjects of the study were ten single-family new construction homes in New Orleans, LA.Data logging equipment was installed at each home in 2012. Interior conditions and various end-use loads were monitored for one year. In terms of averages, the homes with dehumidifiers are limiting elevated levels of humidity in the living space. However, there was significant variation in humidity control between individual houses. An analysis of the equipment operation did not show a clear correlation between energy use and humidity levels. In general, no single explanatory variable appears to provide a consistent understanding of the humidity control in each house. Indoor humidity is likely due to all of the factors we have examined, and the specifics of how they are used by each occupant.« less

Impacts of different aerosol climatologies on the European climate during the last decades

NASA Astrophysics Data System (ADS)

Schultze, Markus; Rockel, Burkhardt

2015-04-01

As summarized in the 5th Assessment Report of the IPCC, the effects of aerosols on the Earth's energy budget are one of the largest uncertainties in a changing climate. Despite a better understanding of aerosol processes since the previous report, it remains unclear to which degree of complexity these processes need to be represented within the climate models to consider their effects in a sufficient manner. Within the nonhydrostatic regional climate model COSMO-CLM, the aerosol climatology of Tanre from 1984 is widely used to simulate the direct effect of aerosols on radiative processes. Apart from a very low spatial resolution and a missing temporal variability, this climatology is dominated by high values of Aerosol Optical Depth (AOD) over Northern Africa, caused by an overestimation of Saharan dust. To investigate the impacts of different aerosol distributions on the European climate, the Tanre aerosol climatology is replaced by the more realistic climatologies of Tegen from 1997 and AEROCOM from 2006 with constant annual cycles of AOD. In addition a control simulation without any aerosol feedbacks was performed. The simulations cover a period of 30 years from 1980 to 2010. In parts of the regions surveyed, we found a near surface cooling, which is strongly linked to AOD, and a broad mid-troposphere warming for all simulations in comparison to the control simulation. A decrease in convective precipitation is mainly caused by stabilization of stratification and by less evapotranspiration resulting from surface cooling. The horizontal differing mid-troposphere warming induces a drop in surface pressure and therefore leads to changes in circulation patterns which are still under investigation. The largest impacts of direct and semi direct aerosol effects was found in summer season. As next step, pre-calculated transient aerosol data will be used to compile an up-to-date aerosol climatology including temporal changes. One main focus of the study will be to investigate whether a decrease in anthropogenic aerosol load in Europe during the last decades enhances the GHG induced near surface warming.

Climate Effects on Methylmercury Bioaccumulation Along a Latitudinal Gradient in the Eastern Canadian Arctic

NASA Astrophysics Data System (ADS)

Chetelat, J.; Richardson, M.; MacMillan, G. A.; Amyot, M.; Hintelmann, H.; Crump, D.

2014-12-01

Recent evidence indicates that inorganic mercury (Hg) loadings to Arctic lakes decline with latitude. However, monomethylmercury (MMHg) concentrations in fish and their prey do not decline in a similar fashion, suggesting that higher latitude lakes are more vulnerable to Hg inputs. Preliminary results will be presented from a three-year study (2012-2015) of climate effects on MMHg bioaccumulation in lakes of the eastern Canadian Arctic. We have investigated mercury transport and accumulation processes in lakes and ponds from three study regions along a latitudinal gradient in climate-controlled ecosystem types in the Canadian Arctic, specifically sub-Arctic taiga, Arctic tundra and polar desert. In each water body, we measured key aspects of MMHg bioaccumulation—MMHg bioavailability to benthic food webs and organism growth rates—as well as how watershed characteristics affect the transport of Hg and organic carbon to lakes. Novel approaches were incorporated including the use of passive samplers (Diffusive Gradient in Thin Film samplers or DGTs) to estimate sediment bioavailable MMHg concentrations and tissue RNA content to compare organism short-term growth rates. A comparison of Arctic tundra and sub-Arctic taiga lakes showed that surface water concentrations of MMHg were strongly and positively correlated to total Hg concentrations both within and among study regions, implying strong control of inorganic Hg supply. Sediment concentrations of bioavailable MMHg were highly variable among lakes, although average concentrations were similar between study regions. Local environmental conditions appear to have a strong influence on sediment potential for MMHg supply. Lake-dwelling Arctic char from tundra lakes had similar or higher total Hg concentrations compared with brook trout from sub-Arctic lakes that were exposed to higher water MMHg concentrations. Potential environmental drivers of these patterns will be discussed. This latitudinal study will provide new information on how climate change may affect temporal and geographic trends of Hg bioaccumulation in the Arctic.

Effects of external loads on balance control during upright stance: experimental results and model-based predictions.

PubMed

Qu, Xingda; Nussbaum, Maury A

2009-01-01

The purpose of this study was to identify the effects of external loads on balance control during upright stance, and to examine the ability of a new balance control model to predict these effects. External loads were applied to 12 young, healthy participants, and effects on balance control were characterized by center-of-pressure (COP) based measures. Several loading conditions were studied, involving combinations of load mass (10% and 20% of individual body mass) and height (at or 15% of stature above the whole-body COM). A balance control model based on an optimal control strategy was used to predict COP time series. It was assumed that a given individual would adopt the same neural optimal control mechanisms, identified in a no-load condition, under diverse external loading conditions. With the application of external loads, COP mean velocity in the anterior-posterior direction and RMS distance in the medial-lateral direction increased 8.1% and 10.4%, respectively. Predicted COP mean velocity and RMS distance in the anterior-posterior direction also increased with external loading, by 11.1% and 2.9%, respectively. Both experimental COP data and model-based predictions provided the same general conclusion, that application of larger external loads and loads more superior to the whole body center of mass lead to less effective postural control and perhaps a greater risk of loss of balance or falls. Thus, it can be concluded that the assumption about consistency in control mechanisms was partially supported, and it is the mechanical changes induced by external loads that primarily affect balance control.

Novel Methods to Explore Building Energy Sensitivity to Climate and Heat Waves Using PNNL's BEND Model

NASA Astrophysics Data System (ADS)

Burleyson, C. D.; Voisin, N.; Taylor, T.; Xie, Y.; Kraucunas, I.

2017-12-01

The DOE's Pacific Northwest National Laboratory (PNNL) has been developing the Building ENergy Demand (BEND) model to simulate energy usage in residential and commercial buildings responding to changes in weather, climate, population, and building technologies. At its core, BEND is a mechanism to aggregate EnergyPlus simulations of a large number of individual buildings with a diversity of characteristics over large spatial scales. We have completed a series of experiments to explore methods to calibrate the BEND model, measure its ability to capture interannual variability in energy demand due to weather using simulations of two distinct weather years, and understand the sensitivity to the number and location of weather stations used to force the model. The use of weather from "representative cities" reduces computational costs, but often fails to capture spatial heterogeneity that may be important for simulations aimed at understanding how building stocks respond to a changing climate (Fig. 1). We quantify the potential reduction in temperature and load biases from using an increasing number of weather stations across the western U.S., ranging from 8 to roughly 150. Using 8 stations results in an average absolute summertime temperature bias of 4.0°C. The mean absolute bias drops to 1.5°C using all available stations. Temperature biases of this magnitude translate to absolute summertime mean simulated load biases as high as 13.8%. Additionally, using only 8 representative weather stations can lead to a 20-40% bias of peak building loads under heat wave or cold snap conditions, a significant error for capacity expansion planners who may rely on these types of simulations. This analysis suggests that using 4 stations per climate zone may be sufficient for most purposes. Our novel approach, which requires no new EnergyPlus simulations, could be useful to other researchers designing or calibrating aggregate building model simulations - particularly those looking at the impact of future climate scenarios. Fig. 1. An example of temperature bias that results from using 8 representative weather stations: (a) surface temperature from NLDAS on 5-July 2008 at 2000 UTC; (b) temperature from 8 representative stations at the same time mapped to all counties within a given IECC climate zone; (c) the difference between (a) and (b).

Variability in Heat Strain in Fully Encapsulated Impermeable Suits in Different Climates and at Different Work Loads.

PubMed

DenHartog, Emiel A; Rubenstein, Candace D; Deaton, A Shawn; Bogerd, Cornelis Peter

2017-03-01

A major concern for responders to hazardous materials (HazMat) incidents is the heat strain that is caused by fully encapsulated impermeable (NFPA 1991) suits. In a research project, funded by the US Department of Defense, the thermal strain experienced when wearing these suits was studied. Forty human subjects between the ages of 25 and 50 participated in a protocol approved by the local ethical committee. Six different fully encapsulated impermeable HazMat suits were evaluated in three climates: moderate (24°C, 50% RH, 20°C WBGT), warm-wet (32°C, 60% RH, 30°C WBGT), and hot-dry (45°C, 20% RH, 37°C WBGT, 200 W m-2 radiant load) and at three walking speeds: 2.5, 4, and 5.5 km h-1. The medium speed, 4 km h-1, was tested in all three climates and the other two walking speeds were only tested in the moderate climate. Prior to the test a submaximal exercise test in normal clothing was performed to determine a relationship between heart rate and oxygen consumption (pretest). In total, 163 exposures were measured. Tolerance time ranged from as low as 20 min in the hot-dry condition to 60 min (the maximum) in the moderate climate, especially common at the lowest walking speed. Between the six difference suits limited differences were found, a two-layered aluminized suit exhibited significant shorter tolerance times in the moderate climate, but no other major significant differences were found for the other climates or workloads. An important characteristic of the overall dataset is the large variability between the subjects. Although the average responses seem suitable to be predicted, the variability in the warmer strain conditions ranged from 20 min up to 60 min. The work load in these encapsulated impermeable suits was also significantly higher than working in normal clothing and higher than predicted by the Pandolf equation. Heart rate showed a very strong correlation to body core temperature and was in many cases the limiting factor. Setting the heart rate maximum at 80% of predicted individual maximum (age based) would have prevented 95% of the cases with excessive heat strain. Monitoring of heart rate under operational conditions would further allow individually optimize working times and help in preventing exertional heat stroke. © The Author 2017. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

Improving the performance of air-conditioning systems in an ASEAN (Association of South East Asian Nations) climate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Busch, J.F.; Warren, M.L.

1988-09-01

This paper describes an analysis of air conditioning performance under hot and humid tropical climate conditions appropriate to the Association of South East Asian Nations (ASEAN) countries. This region, with over 280 million people, has one of the fastest economic and energy consumption growth rates in the world. The work reported here is aimed at estimating the conservation potential derived from good design and control of air conditioning systems in commercial buildings. To test the performance of different air conditioning system types and control options, whole building energy performance was simulated using DOE-2. The 5100 m/sup 2/ (50,000 ft/sup 2/)more » prototype office building module was previously used in earlier commercial building energy standards analysis for Malaysia and Singapore. In general, the weather pattern for ASEAN countries is uniform, with hot and humid air masses known as ''monsoons'' dictating the weather patterns. Since a concentration of cities occurs near the tip of the Malay peninsula, hourly temperature, humidity, and wind speed data for Kuala Lumpur was used for the analysis. Because of the absence of heating loads in ASEAN regions, we have limited air conditioning configurations to two pipe fan coil, constant volume, variable air volume, powered induction, and ceiling bypass configurations. Control strategies were varied to determine the conservation potential in both energy use and peak electric power demands. Sensitivities including fan control, pre-cooling and night ventilation, supply air temperature control, zone temperature set point, ventilation and infiltration, daylighting and internal gains, and system sizing were examined and compared with a base case which was a variable air volume system with no reheat or economizer. Comfort issues, such as over-cooling and space humidity, were also examined.« less

14 CFR 23.395 - Control system loads.

Code of Federal Regulations, 2013 CFR

2013-01-01

... Loads § 23.395 Control system loads. (a) Each flight control system and its supporting structure must be... at the appropriate control grips or pads as they would in flight, and to react at the attachments of... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Control system loads. 23.395 Section 23.395...

Post-Glacial Climate Forcing of Surface Processes in the Ganges-Brahmaputra Basin and Implications for the Global Carbon Cycle

NASA Astrophysics Data System (ADS)

Hein, C. J.; Galy, V.; France-Lanord, C.; Galy, A.; Kudrass, H. R.; Peucker-Ehrenbrink, B.

2016-12-01

Silicate weathering coupled with carbonate precipitation and organic carbon (OC) burial in marine sediments are the primary mechanisms sequestering atmospheric CO2 over a range of timescales. The efficiency of both processes has long been mechanistically linked to climate: increased atmospheric CO2 sequestration under warm/wet conditions acts as a negative feedback, thereby contributing to global climate regulation. Over glacial-interglacial timescales, climate has been proposed to control the export rate of terrestrial silicate weathering products and terrestrial OC to river-dominated margins, as well as the rates of chemical weathering (i.e., the efficiency of carbon sequestration). Focused on the Ganges-Brahmaputra drainage basin, this study quantifies the relative role of climate change in the efficiency of silicate weathering and OC burial following the last glacial maximum. Stable hydrogen (δD) and carbon (δ13C) isotopic compositions of terrestrial plant wax compounds preserved in the Bengal Fan channel-levee system capture variations in the strength of the Indian summer monsoon and vegetation dynamics. Specifically, a 40‰ shift in δD and a 4‰ shift in both bulk OC and plant wax δ13C values between the late glacial and mid-Holocene, followed by a return to more intermediate values during the late Holocene, correlate well with regional post-glacial paleoclimate records. Sediment provenance proxies (Sr, Nd isotopic compositions) reveal that these changes coincided with a focusing of erosion on the southern flank of the Himalayan range during periods of greater monsoon strength and enhanced sediment discharge. However, OC loading, and thus carbon burial efficiency, in the Bengal Fan remained constant through time, demonstrating the primacy of physical erosion and climate-driven sediment export in marine OC sequestration. In contrast, a gradual increase in K/Si* and Ca/Si, and decrease in H2O+/Si*, throughout the study period may demonstrate the decoupling of climate and silicate weathering during the late Holocene, if those ratios are valid proxies for catchment-scale chemical weathering intensity. Together, these results reveal the dominant feedback between climate and sediment-export / OC-burial within the Ganges-Brahmaputra / Bengal Fan system following deglaciation.

Nutrient and Suspended-Sediment Transport and Trends in the Columbia River and Puget Sound Basins, 1993-2003

USGS Publications Warehouse

Wise, Daniel R.; Rinella, Frank A.; Rinella, Joseph F.; Fuhrer, Greg J.; Embrey, Sandra S.; Clark, Gregory M.; Schwarz, Gregory E.; Sobieszczyk, Steven

2007-01-01

This study focused on three areas that might be of interest to water-quality managers in the Pacific Northwest: (1) annual loads of total nitrogen (TN), total phosphorus (TP) and suspended sediment (SS) transported through the Columbia River and Puget Sound Basins, (2) annual yields of TN, TP, and SS relative to differences in landscape and climatic conditions between subbasin catchments (drainage basins), and (3) trends in TN, TP, and SS concentrations and loads in comparison to changes in landscape and climatic conditions in the catchments. During water year 2000, an average streamflow year in the Pacific Northwest, the Columbia River discharged about 570,000 pounds per day of TN, about 55,000 pounds per day of TP, and about 14,000 tons per day of SS to the Pacific Ocean. The Snake, Yakima, Deschutes, and Willamette Rivers contributed most of the load discharged to the Columbia River. Point-source nutrient loads to the catchments (almost exclusively from municipal wastewater treatment plants) generally were a small percentage of the total in-stream nutrient loads; however, in some reaches of the Spokane, Boise, Walla Walla, and Willamette River Basins, point sources were responsible for much of the annual in-stream nutrient load. Point-source nutrient loads generally were a small percentage of the total catchment nutrient loads compared to nonpoint sources, except for a few catchments where point-source loads comprised as much as 30 percent of the TN load and as much as 80 percent of the TP load. The annual TN and TP loads from point sources discharging directly to the Puget Sound were about equal to the annual loads from eight major tributaries. Yields of TN, TP, and SS generally were greater in catchments west of the Cascade Range. A multiple linear regression analysis showed that TN yields were significantly (p < 0.05) and positively related to precipitation, atmospheric nitrogen load, fertilizer and manure load, and point-source load, and were negatively related to average slope. TP yields were significantly related positively to precipitation, and point-source load and SS yields were significantly related positively to precipitation. Forty-eight percent of the available monitoring sites for TN had significant trends in concentration (2 increasing, 19 decreasing), 32 percent of the available sites for TP had significant trends in concentration (7 increasing, 9 decreasing), and 40 percent of the available sites for SS had significant trends in concentration (4 increasing, 15 decreasing). The trends in load followed a similar pattern, but with fewer sites showing significant trends. The results from this study indicate that inputs from nonpoint sources of nutrients probably have decreased over time in many of the catchments. Despite the generally small contribution of point-source nutrient loads, they still may have been partially responsible for the significant decreasing trends for nutrients at sites where the total point-source nutrient loads to the catchments equaled a substantial proportion of the in-stream load.

Ground reaction force comparison of controlled resistance methods to isoinertial loading of the squat exercise - biomed 2010.

PubMed

Paulus, David C; Reynolds, Michael C; Schilling, Brian K

2010-01-01

The ground reaction force during the concentric (raising) portion of the squat exercise was compared to that of isoinertial loading (free weights) for three pneumatically controlled resistance methods: constant resistance, cam force profile, and proportional force control based on velocity. Constant force control showed lower ground reaction forces than isoinertial loading throughout the range of motion (ROM). The cam force profile exhibited slightly greater ground reaction forces than isoinertial loading at 10 and 40% ROM with fifty-percent greater loading at 70% ROM. The proportional force control consistently elicited greater ground reaction force than isoinertial loading, which progressively ranged from twenty to forty percent increase over isoinertial loading except for being approximately equal at 85% ROM. Based on these preliminary results, the proportional control shows the most promise for providing loading that is comparable in magnitude to isoinertial loading. This technology could optimize resistance exercise for sport-specific training or as a countermeasure to atrophy during spaceflight.

Interactive effects of reactive nitrogen and climate change on US water resources

NASA Astrophysics Data System (ADS)

Baron, J.; Bernhardt, E. S.; Finlay, J. C.; Chan, F.; Nolan, B. T.; Howarth, B.; Hall, E.; Boyer, E. W.

2011-12-01

Water resources and aquatic ecosystems are increasingly strained by withdrawals for agriculture and drinking water supply, nitrogen and other pollutant inputs, and climate change. We describe current and projected effects of the interactions of reactive nitrogen (N) and climate change on water resources of the United States. As perturbations to the N cycle intensify in a warmer less predictable climate, interactions will negatively affect the services we expect of our water resources. There are also feedbacks to the climate system itself through the production of greenhouse gases. We conclude: 1. Nitrogen concentrations will increase in the nation's waters from increased N loading and higher N mineralization rates. N export from terrestrial to aquatic ecosystems exhibits a high sensitivity to climate variations. 2. Consequences range from eutrophication and acidification, which reduce natural biodiversity and harm economically valuable fisheries, to adverse impacts on human health. 3. Extreme flood events have the potential to transport N rapidly long distances downstream from its source. 4. A recent national assessment found 67% of streams derived more than 37% of their total nitrate load from base flow often derived from groundwater. Long residence times for groundwater nitrate below agricultural fields may cause benefits from proper N management practices to take decades to be realized under current and future climates. 5. Streams, wetlands, rivers, lakes, estuaries and continental shelves are hotspots for denitrification. Maintenance of N removal capacity thus a critical component of eutrophication management under changing climate and land use conditions. 6. The amount of N inputs from fertilizer and manure use, human population, and deposition is tightly coupled with hydrology to influence the rates and proportion of N emitted to the atmosphere as N2O. About 20% of global N2O emissions come from groundwater, lakes, rivers, and estuaries; stream and wetland emissions add to this value. 7. If current patterns of N and water resource management continue, nitrogen loading to inland waters is expected to increase while the nitrogen retention efficiency within aquatic ecosystems will decline as a function of nitrogen saturation of biological demand. 8. Management that reduces N loss to the nation's water will reduce environmental and economic damage, reduce the risk to human health, and prevent the production of some N2O. Preventing the loss of N to aquatic systems is likely to be most effective at its point of origin. Reducing reactive nitrogen emissions to the atmosphere, increasing N uptake efficiency of crops and greater N retention in soils, better animal management, and improved sewage treatment to remove N from urban waste waters will be increasingly important approaches for the provision of water resources and services in a warmer and highly populated world.

Physiological and Subjective Evaluation of the Temperate Battle Dress Uniform (TBDU) and Three Other Uniforms Worn by Men and Women in Tropical Climatic Conditions

DTIC Science & Technology

1983-05-01

worn in the heat affects thermal comfort and with an added solar heat load subsequently interferes with the ability to dissipate stored body heat...worn in the heat affects thermal comfort and with an added solar heat load subsequently interferes with the ability to dissipate stored body heat...ratio; thermal comfort ; evaporative cooling; permeability; physiological responses mA]X .................................... INTRODUCTION The Temperate

Improved predictions of atmospheric icing in Norway

NASA Astrophysics Data System (ADS)

Engdahl, Bjørg Jenny; Nygaard, Bjørn Egil; Thompson, Gregory; Bengtsson, Lisa; Berntsen, Terje

2017-04-01

Atmospheric icing of ground structures is a problem in cold climate locations such as Norway. During the 2013/2014 winter season two major power lines in southern Norway suffered severe damage due to ice loads exceeding their design values by two to three times. Better methods are needed to estimate the ice loads that affect various infrastructure, and better models are needed to improve the prediction of severe icing events. The Wind, Ice and Snow loads Impact on Infrastructure and the Natural Environment (WISLINE) project, was initiated to address this problem and to explore how a changing climate may affect the ice loads in Norway. Creating better forecasts of icing requires a proper simulation of supercooled liquid water (SLW). Preliminary results show that the operational numerical weather prediction model (HARMONIE-AROME) at MET-Norway generates considerably lower values of SLW as compared with the WRF model when run with the Thompson microphysics scheme. Therefore, we are piecewise implementing specific processes found in the Thompson scheme into the AROME model and testing the resulting impacts to prediction of SLW and structural icing. Both idealized and real icing cases are carried out to test the newly modified AROME microphysics scheme. Besides conventional observations, a unique set of specialized instrumentation for icing measurements are used for validation. Initial results of this investigation will be presented at the conference.

Storm Water Retention on Three Green Roofs with Distinct Climates

NASA Astrophysics Data System (ADS)

Breach, P. A.; Sims, A.; O'Carroll, D. M.; Robinson, C. E.; Smart, C. C.; Powers, B. S. C.

2014-12-01

As urbanization continues to increase the impact of cities on their surrounding environments, the feasibility of implementing low-impact development such as green roofs is of increasing interest. Green roofs retain and attenuate storm water thereby reducing the load on urban sewer systems. In addition, green roofs can provide insulation and lower roof surface temperature leading to a decrease in building energy load. Green roof technology in North American urban environments remains underused, in part due to a lack of climate appropriate green roof design guidelines. The capacity of a green roof to moderate runoff depends on the storage capacity of the growing medium at the start of a rainfall event. Storage capacity is finite, which makes rapid drainage and evapotranspiration loss critical for maximizing storage capacity between subsequent storms. Here the retention and attenuation of storm events are quantified for experimental green roof sites located in three representative Canadian climates corresponding to; semiarid conditions in Calgary, Alberta, moderate conditions in London, Ontario, and cool and humid conditions in Halifax, Nova Scotia. The storage recovery and storm water retention at each site is modelled using a modified water balance approach. Components of the water balance including evapotranspiration are predicted using climate data collected from 2012 to 2014 at each of the experimental sites. During the measurement period there were over 300 precipitation events ranging from small, frequent events (< 2 mm) to a storm with a 250 year return period. The modeling approach adopted provides a tool for planners to assess the feasibility of implementing green roofs in their respective climates.

Influences of load characteristics on impaired control of grip forces in patients with cerebellar damage.

PubMed

Brandauer, B; Timmann, D; Häusler, A; Hermsdörfer, J

2010-02-01

Various studies showed a clear impairment of cerebellar patients to modulate grip force in anticipation of the loads resulting from movements with a grasped object. This failure corroborated the theory of internal feedforward models in the cerebellum. Cerebellar damage also impairs the coordination of multiple-joint movements and this has been related to deficient prediction and compensation of movement-induced torques. To study the effects of disturbed torque control on feedforward grip-force control, two self-generated load conditions with different demands on torque control-one with movement-induced and the other with isometrically generated load changes-were directly compared in patients with cerebellar degeneration. Furthermore the cerebellum is thought to be more involved in grip-force adjustment to self-generated loads than to externally generated loads. Consequently, an additional condition with externally generated loads was introduced to further test this hypothesis. Analysis of 23 patients with degenerative cerebellar damage revealed clear impairments in predictive feedforward mechanisms in the control of both self-generated load types. Besides feedforward control, the cerebellar damage also affected more reactive responses when the externally generated load destabilized the grip, although this impairment may vary with the type of load as suggested by control experiments. The present findings provide further support that the cerebellum plays a major role in predictive control mechanisms. However, this impact of the cerebellum does not strongly depend on the nature of the load and the specific internal forward model. Contributions to reactive (grip force) control are not negligible, but seem to be dependent on the physical characteristics of an externally generated load.

Key ecological responses to nitrogen are altered by climate ...

EPA Pesticide Factsheets

Here we review the effects of nitrogen and climate (e.g. temperature and precipitation) on four aspects of ecosystem structure and function including hydrologic-coupled nitrogen cycling, carbon cycling, acidification and biodiversity. Ecosystems are simultaneously exposed to multiple stressors; two dominant drivers threatening ecosystems are anthropogenic nitrogen loading and climate change. Evaluating the cumulative effects of these stressors provides a holistic view of ecosystem vulnerability, which would better inform policy decisions aimed to protect the sustainability of ecosystems. Our current knowledge of the cumulative effects of these stressors is growing, but limited. The goal of this paper is to synthesize the state of scientific knowledge on how ecosystems are affected by the interactions of meteorlogic/climatic factors (e.g., temperature and precipitation) and nitrogen addition. Understanding the interactions of meteorlogic/climatic factors and nitrogen will help to inform how current and projected variability may affect ecosystem response.

Modeling Nitrogen Processing in Northeast US River Networks

NASA Astrophysics Data System (ADS)

Whittinghill, K. A.; Stewart, R.; Mineau, M.; Wollheim, W. M.; Lammers, R. B.

2013-12-01

Due to increased nitrogen (N) pollution from anthropogenic sources, the need for aquatic ecosystem services such as N removal has also increased. River networks provide a buffering mechanism that retains or removes anthropogenic N inputs. However, the effectiveness of N removal in rivers may decline with increased loading and, consequently, excess N is eventually delivered to estuaries. We used a spatially distributed river network N removal model developed within the Framework for Aquatic Modeling in the Earth System (FrAMES) to examine the geography of N removal capacity of Northeast river systems under various land use and climate conditions. FrAMES accounts for accumulation and routing of runoff, water temperatures, and serial biogeochemical processing using reactivity derived from the Lotic Intersite Nitrogen Experiment (LINX2). Nonpoint N loading is driven by empirical relationships with land cover developed from previous research in Northeast watersheds. Point source N loading from wastewater treatment plants is estimated as a function of the population served and the volume of water discharged. We tested model results using historical USGS discharge data and N data from historical grab samples and recently initiated continuous measurements from in-situ aquatic sensors. Model results for major Northeast watersheds illustrate hot spots of ecosystem service activity (i.e. N removal) using high-resolution maps and basin profiles. As expected, N loading increases with increasing suburban or agricultural land use area. Network scale N removal is highest during summer and autumn when discharge is low and river temperatures are high. N removal as the % of N loading increases with catchment size and decreases with increasing N loading, suburban land use, or agricultural land use. Catchments experiencing the highest network scale N removal generally have N inputs (both point and non-point sources) located in lower order streams. Model results can be used to better predict nutrient loading to the coastal ocean across a broad range of current and future climate variability.

Synchronous fire activity in the tropical high Andes: an indication of regional climate forcing.

PubMed

Román-Cuesta, R M; Carmona-Moreno, C; Lizcano, G; New, M; Silman, M; Knoke, T; Malhi, Y; Oliveras, I; Asbjornsen, H; Vuille, M

2014-06-01

Global climate models suggest enhanced warming of the tropical mid and upper troposphere, with larger temperature rise rates at higher elevations. Changes in fire activity are amongst the most significant ecological consequences of rising temperatures and changing hydrological properties in mountainous ecosystems, and there is a global evidence of increased fire activity with elevation. Whilst fire research has become popular in the tropical lowlands, much less is known of the tropical high Andean region (>2000 masl, from Colombia to Bolivia). This study examines fire trends in the high Andes for three ecosystems, the Puna, the Paramo and the Yungas, for the period 1982-2006. We pose three questions: (i) is there an increased fire response with elevation? (ii) does the El Niño- Southern Oscillation control fire activity in this region? (iii) are the observed fire trends human driven (e.g., human practices and their effects on fuel build-up) or climate driven? We did not find evidence of increased fire activity with elevation but, instead, a quasicyclic and synchronous fire response in Ecuador, Peru and Bolivia, suggesting the influence of high-frequency climate forcing on fire responses on a subcontinental scale, in the high Andes. ENSO variability did not show a significant relation to fire activity for these three countries, partly because ENSO variability did not significantly relate to precipitation extremes, although it strongly did to temperature extremes. Whilst ENSO did not individually lead the observed regional fire trends, our results suggest a climate influence on fire activity, mainly through a sawtooth pattern of precipitation (increased rainfall before fire-peak seasons (t-1) followed by drought spells and unusual low temperatures (t0), which is particularly common where fire is carried by low fuel loads (e.g., grasslands and fine fuel). This climatic sawtooth appeared as the main driver of fire trends, above local human influences and fuel build-up cyclicity. © 2014 John Wiley & Sons Ltd.

Examining the recent climate through the lens of ecology: inferences from temporal pattern analysis.

Treesearch

Paul F. Hessburg; Ellen E. Kuhlmann; Thomas W. Swetnam

2005-01-01

Ecological theory asserts that the climate of a region exerts top-down controls on regional ecosystem patterns and processes, across space and time. To provide empirical evidence of climatic controls, it would be helpful to define climatic regions that minimized variance in key climate attributes, within climatic regions-define the periods and features of climatic...

Development of Environmental Load Estimation Model for Road Drainage Systems in the Early Design Phase

NASA Astrophysics Data System (ADS)

Park, Jin-Young; Lee, Dong-Eun; Kim, Byung-Soo

2017-10-01

Due to the increasing concern about climate change, efforts to reduce environmental load are continuously being made in construction industry, and LCA (life cycle assessment) is being presented as an effective method to assess environmental load. Since LCA requires information on construction quantity used for environmental load estimation, however, it is not being utilized in the environmental review in the early design phase where it is difficult to obtain such information. In this study, computation system for construction quantity based on standard cross section of road drainage facilities was developed to compute construction quantity required for LCA using only information available in the early design phase to develop and verify the effectiveness of a model that can perform environmental load estimation. The result showed that it is an effective model that can be used in the early design phase as it revealed a 13.39% mean absolute error rate.

[Effect analysis on the two total load control methods for poisonous heavy metals].

PubMed

Fu, Guo-Wei

2012-12-01

Firstly it should be made clear that implementation of source total load control for the first type of pollutants is necessary for environmental pollution control legislation and economic structure regulation. This kind of surveillance method has been more practical to be implemented since the Manual of the Industry Discharge Coefficient of First National Pollution Sources Investigation was published. The source total load control and water environment total load control are independent of each other and none of them is redundant, on the other side they can be complementary to each other. In the present, some local planning managers are blurring and confusing the contents and styles of the two surveillance methods. They just use the water total load control to manage all the pollutants, and source total load control is discarded, which results in the loss of control for the first type of pollutants especially for the drinking water source surveillance. There is a big difference between the water quality standards and the water environmental background concentration values for the first type of pollutants in the Environmental quality standard for surface water (GB 3838-88), which means that there are problems such as "relaxing the pollutant discharge permit" and "risk induced by valence state change". Taking an enterprise with 10t electrolytic lead production capacity as an example, there is a big difference between the allowable lead discharged loads by the two total load surveillance methods. In summary, it will bring a lot of harmful effects if the water total load control is implemented for the two types of pollutants, so the source total load control and water environmental total load control should be implemented strictly at the same time.

Air-to-Water Heat Pumps With Radiant Delivery in Low-Load Homes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Backman, C.; German, A.; Dakin, B.

2013-12-01

Space conditioning represents nearly 50% of average residential household energy consumption, highlighting the need to identify alternative cost-effective, energy-efficient cooling and heating strategies. As homes are better built, there is an increasing need for strategies that are particularly well suited for high performance, low load homes. ARBI researchers worked with two test homes in hot-dry climates to evaluate the in-situ performance of air-to-water heat pump (AWHP) systems, an energy efficient space conditioning solution designed to cost-effectively provide comfort in homes with efficient, safe, and durable operation. Two monitoring projects of test houses in hot-dry climates were initiated in 2010 tomore » test this system. Both systems were fully instrumented and have been monitored over one year to capture complete performance data over the cooling and heating seasons. Results are used to quantify energy savings, cost-effectiveness, and system performance using different operating modes and strategies. A calibrated TRNSYS model was developed and used to evaluate performance in various climate regions. This strategy is most effective in tight, insulated homes with high levels of thermal mass (i.e. exposed slab floors).« less

Why do general circulation models overestimate the aerosol cloud lifetime effect? A case study comparing CAM5 and a CRM

DOE PAGES

Zhou, Cheng; Penner, Joyce E.

2017-01-02

Observation-based studies have shown that the aerosol cloud lifetime effect or the increase of cloud liquid water path (LWP) with increased aerosol loading may have been overestimated in climate models. Here, we simulate shallow warm clouds on 27 May 2011 at the southern Great Plains (SGP) measurement site established by the Department of Energy's (DOE) Atmospheric Radiation Measurement (ARM) program using a single-column version of a global climate model (Community Atmosphere Model or CAM) and a cloud resolving model (CRM). The LWP simulated by CAM increases substantially with aerosol loading while that in the CRM does not. The increase of LWP inmore » CAM is caused by a large decrease of the autoconversion rate when cloud droplet number increases. In the CRM, the autoconversion rate is also reduced, but this is offset or even outweighed by the increased evaporation of cloud droplets near the cloud top, resulting in an overall decrease in LWP. Lastly, our results suggest that climate models need to include the dependence of cloud top growth and the evaporation/condensation process on cloud droplet number concentrations.« less

A GUI Based Software for Sizing Stand Alone AC Coupled Hybrid PV-Diesel Power System under Malaysia Climate

NASA Astrophysics Data System (ADS)

Syafiqah Syahirah Mohamed, Nor; Amalina Banu Mohamat Adek, Noor; Hamid, Nurul Farhana Abd

2018-03-01

This paper presents the development of Graphical User Interface (GUI) software for sizing main component in AC coupled photovoltaic (PV) hybrid power system based on Malaysia climate. This software provides guideline for PV system integrator to design effectively the size of components and system configuration to match the system and load requirement with geographical condition. The concept of the proposed software is balancing the annual average renewable energy generation and load demand. In this study, the PV to diesel generator (DG) ratio is introduced by considering the hybrid system energy contribution. The GUI software is able to size the main components in the PV hybrid system to meet with the set target of energy contribution ratio. The rated powers of the components to be defined are PV array, grid-tie inverter, bi-directional inverter, battery storage and DG. GUI is used to perform all the system sizing procedures to make it user friendly interface as a sizing tool for AC coupled PV hybrid system. The GUI will be done by using Visual Studio 2015 based on the real data under Malaysia Climate.

Cattle, clean water, and climate change: policy choices for the Brazilian Agricultural Frontier.

PubMed

Bell, Andrew Reid; Lemos, Maria Carmen; Scavia, Donald

2010-11-15

In the Amazonian agricultural frontier, pasture for cattle ranching is an important and potentially hazardous form of land use because of sediment erosion as pastures degrade. This relationship between ranching, sediment load, and water quality is likely to further exacerbate environmental impacts, particularly in the context of climate change. We examine the role that river basin councils (RBCs) - a water governance option of Brazil's 1997 National Water Act - might play in managing this nonpoint-source pollution in the Amazônian state of Rondônia. We implement a simple coupled rancher-water system model to compare two potential governance options: a bulk water cleanup charge (BWC) implemented by RBCs and a land-use fine (LUF) for failing to maintain riparian buffers. We find no significant advantage of BWC over LUF in reducing sediment loading while keeping ranching profitable, under a changing climate. We also fail to find in Rondônia the important stake in water issues that has driven water reform elsewhere in Brazil. Moreover, the comparative success of reforestation programs suggests these programs may, in fact, have the potential to manage nonpoint-source agricultural pollution in the region.

Why do general circulation models overestimate the aerosol cloud lifetime effect? A case study comparing CAM5 and a CRM

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, Cheng; Penner, Joyce E.

Observation-based studies have shown that the aerosol cloud lifetime effect or the increase of cloud liquid water path (LWP) with increased aerosol loading may have been overestimated in climate models. Here, we simulate shallow warm clouds on 27 May 2011 at the southern Great Plains (SGP) measurement site established by the Department of Energy's (DOE) Atmospheric Radiation Measurement (ARM) program using a single-column version of a global climate model (Community Atmosphere Model or CAM) and a cloud resolving model (CRM). The LWP simulated by CAM increases substantially with aerosol loading while that in the CRM does not. The increase of LWP inmore » CAM is caused by a large decrease of the autoconversion rate when cloud droplet number increases. In the CRM, the autoconversion rate is also reduced, but this is offset or even outweighed by the increased evaporation of cloud droplets near the cloud top, resulting in an overall decrease in LWP. Lastly, our results suggest that climate models need to include the dependence of cloud top growth and the evaporation/condensation process on cloud droplet number concentrations.« less

Data Management System for the National Energy-Water System (NEWS) Assessment Framework

NASA Astrophysics Data System (ADS)

Corsi, F.; Prousevitch, A.; Glidden, S.; Piasecki, M.; Celicourt, P.; Miara, A.; Fekete, B. M.; Vorosmarty, C. J.; Macknick, J.; Cohen, S. M.

2015-12-01

Aiming at providing a comprehensive assessment of the water-energy nexus, the National Energy-Water System (NEWS) project requires the integration of data to support a modeling framework that links climate, hydrological, power production, transmission, and economical models. Large amounts of Georeferenced data has to be streamed to the components of the inter-disciplinary model to explore future challenges and tradeoffs in the US power production, based on climate scenarios, power plant locations and technologies, available water resources, ecosystem sustainability, and economic demand. We used open source and in-house build software components to build a system that addresses two major data challenges: On-the-fly re-projection, re-gridding, interpolation, extrapolation, nodata patching, merging, temporal and spatial aggregation, of static and time series datasets in virtually any file formats and file structures, and any geographic extent for the models I/O, directly at run time; Comprehensive data management based on metadata cataloguing and discovery in repositories utilizing the MAGIC Table (Manipulation and Geographic Inquiry Control database). This innovative concept allows models to access data on-the-fly by data ID, irrespective of file path, file structure, file format and regardless its GIS specifications. In addition, a web-based information and computational system is being developed to control the I/O of spatially distributed Earth system, climate, and hydrological, power grid, and economical data flow within the NEWS framework. The system allows scenario building, data exploration, visualization, querying, and manipulation any loaded gridded, point, and vector polygon dataset. The system has demonstrated its potential for applications in other fields of Earth science modeling, education, and outreach. Over time, this implementation of the system will provide near real-time assessment of various current and future scenarios of the water-energy nexus.

Potential modulations of pre-monsoon aerosols during El Niño: impact on Indian summer monsoon

NASA Astrophysics Data System (ADS)

Fadnavis, S.; Roy, Chaitri; Sabin, T. P.; Ayantika, D. C.; Ashok, K.

2017-10-01

The potential role of aerosol loading on the Indian summer monsoon rainfall during the El Niño years are examined using satellite-derived observations and a state of the art fully interactive aerosol-chemistry-climate model. The Aerosol Index (AI) from TOMS (1978-2005) and Aerosol Optical Depth (AOD) from MISR spectroradiometer (2000-2010) indicate a higher-than-normal aerosol loading over the Indo-Gangetic plain (IGP) during the pre-monsoon season with a concurrent El Niño. Sensitivity experiments using ECHAM5-HAMMOZ climate model suggests that this enhanced loading of pre-monsoon absorbing aerosols over the Indo-Gangetic plain can reduce the drought during El Niño years by invoking the `Elevated-Heat-Pump' mechanism through an anomalous aerosol-induced warm core in the atmospheric column. This anomalous heating upshot the relative strengthening of the cross-equatorial moisture inflow associated with the monsoon and eventually reduces the severity of drought during El Niño years. The findings are subject to the usual limitations such as the uncertainties in observations, and limited number of El Niño years (during the study period).

Eutrophication effects on greenhouse gas fluxes from shallow-lake mesocosms override those of climate warming.

PubMed

Davidson, Thomas A; Audet, Joachim; Svenning, Jens-Christian; Lauridsen, Torben L; Søndergaard, Martin; Landkildehus, Frank; Larsen, Søren E; Jeppesen, Erik

2015-12-01

Fresh waters make a disproportionately large contribution to greenhouse gas (GHG) emissions, with shallow lakes being particular hot spots. Given their global prevalence, how GHG fluxes from shallow lakes are altered by climate change may have profound implications for the global carbon cycle. Empirical evidence for the temperature dependence of the processes controlling GHG production in natural systems is largely based on the correlation between seasonal temperature variation and seasonal change in GHG fluxes. However, ecosystem-level GHG fluxes could be influenced by factors, which while varying seasonally with temperature are actually either indirectly related (e.g. primary producer biomass) or largely unrelated to temperature, for instance nutrient loading. Here, we present results from the longest running shallow-lake mesocosm experiment which demonstrate that nutrient concentrations override temperature as a control of both the total and individual GHG flux. Furthermore, testing for temperature treatment effects at low and high nutrient levels separately showed only one, rather weak, positive effect of temperature (CH4 flux at high nutrients). In contrast, at low nutrients, the CO2 efflux was lower in the elevated temperature treatments, with no significant effect on CH4 or N2 O fluxes. Further analysis identified possible indirect effects of temperature treatment. For example, at low nutrient levels, increased macrophyte abundance was associated with significantly reduced fluxes of both CH4 and CO2 for both total annual flux and monthly observation data. As macrophyte abundance was positively related to temperature treatment, this suggests the possibility of indirect temperature effects, via macrophyte abundance, on CH4 and CO2 flux. These findings indicate that fluxes of GHGs from shallow lakes may be controlled more by factors indirectly related to temperature, in this case nutrient concentration and the abundance of primary producers. Thus, at ecosystem scale, response to climate change may not follow predictions based on the temperature dependence of metabolic processes. © 2015 John Wiley & Sons Ltd.

14 CFR 27.681 - Limit load static tests.

Code of Federal Regulations, 2013 CFR

2013-01-01

... AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Design and Construction Control Systems § 27.681 Limit load... which— (1) The direction of the test loads produces the most severe loading in the control system; and... requirements for control system joints subject to angular motion. ...

Effect of counter-pulsation control of a pulsatile left ventricular assist device on working load variations of the native heart.

PubMed

Choi, Seong Wook; Nam, Kyoung Won; Lim, Ki Moo; Shim, Eun Bo; Won, Yong Soon; Woo, Heung Myong; Kwak, Ho Hyun; Noh, Mi Ryoung; Kim, In Young; Park, Sung Min

2014-04-03

When using a pulsatile left ventricular assist device (LVAD), it is important to reduce the cardiac load variations of the native heart because severe cardiac load variations can induce ventricular arrhythmia. In this study, we investigated the effect of counter-pulsation control of the LVAD on the reduction of cardiac load variation. A ventricular electrocardiogram-based counter-pulsation control algorithm for a LVAD was implemented, and the effects of counter-pulsation control of the LVAD on the reduction of the working load variations of the left ventricle were determined in three animal experiments. Deviations of the working load of the left ventricle were reduced by 51.3%, 67.9%, and 71.5% in each case, and the beat-to-beat variation rates in the working load were reduced by 84.8%, 82.7%, and 88.2% in each ease after counter-pulsation control. There were 3 to 12 premature ventricle contractions (PVCs) before counter-pulsation control, but no PVCs were observed during counter-pulsation control. Counter-pulsation control of the pulsatile LVAD can reduce severe cardiac load variations, but the average working load is not markedly affected by application of counter-pulsation control because it is also influenced by temporary cardiac outflow variations. We believe that counter-pulsation control of the LVAD can improve the long-term safety of heart failure patients equipped with LVADs.

Modern Climate Analogues of Late-Quaternary Paleoclimates for the Western United States.

NASA Astrophysics Data System (ADS)

Mock, Cary Jeffrey

This study examined spatial variations of modern and late-Quaternary climates for the western United States. Synoptic climatological analyses of the modern record identified the predominate climatic controls that normally produce the principal modes of spatial climatic variability. They also provided a modern standard to assess past climates. Maps of the month-to-month changes in 500 mb heights, sea-level pressure, temperature, and precipitation illustrated how different climatic controls govern the annual cycle of climatic response. The patterns of precipitation ratios, precipitation bar graphs, and the seasonal precipitation maximum provided additional insight into how different climatic controls influence spatial climatic variations. Synoptic-scale patterns from general circulation model (GCM) simulations or from analyses of climatic indices were used as the basis for finding modern climate analogues for 18 ka and 9 ka. Composite anomaly maps of atmospheric circulation, precipitation, and temperature were compared with effective moisture maps compiled from proxy data to infer how the patterns, which were evident from the proxy data, were generated. The analyses of the modern synoptic climatology indicate that smaller-scale climatic controls must be considered along with larger-scale ones in order to explain patterns of spatial climate heterogeneity. Climatic extremes indicate that changes in the spatial patterns of precipitation seasonality are the exception rather than the rule, reflecting the strong influence of smaller-scale controls. Modern climate analogues for both 18 ka and 9 ka clearly depict the dry Northwest/wet Southwest contrast that is suggested by GCM simulations and paleoclimatic evidence. 18 ka analogues also show the importance of smaller-scale climatic controls in explaining spatial climatic variation in the Northwest and northern Great Plains. 9 ka analogues provide climatological explanations for patterns of spatial heterogeneity over several mountainous areas as suggested by paleoclimatic evidence. Modern analogues of past climates supplement modeling approaches by providing information below the resolution of model simulations. Analogues can be used to examine the controls of spatial paleoclimatic variation if sufficient instrumental data and paleoclimatic evidence are available, and if one carefully exercises uniformitarianism when extrapolating modern relationships to the past.

Testing the sensitivity of past climates to the indirect effects of dust

NASA Astrophysics Data System (ADS)

Sagoo, Navjit; Storelvmo, Trude

2017-06-01

Mineral dust particles are important ice nuclei (IN) and as such indirectly impact Earth's radiative balance via the properties of cold clouds. Using the Community Earth System Model version 1.0.6, and Community Atmosphere Model version 5.1, and a new empirical parameterization for ice nucleation on dust particles, we investigate the radiative forcing induced by dust IN for different dust loadings. Dust emissions are representative of global conditions for the Last Glacial Maximum and the mid-Pliocene Warm Period. Increased dust leads to smaller and more numerous ice crystals in mixed phase clouds, impacting cloud opacity, lifetime, and precipitation. This increases the shortwave cloud radiative forcing, resulting in significant surface temperature cooling and polar amplification—which is underestimated in existing studies relative to paleoclimate archives. Large hydrological changes occur and are linked to an enhanced dynamical response. We conclude that dust indirect effects could potentially have a significant impact on the model-data mismatch that exists for paleoclimates.