Variations In Meteorological Conditions Research Articles

Plant responses to elevated CO2 levels in soils: Distinct CO2 and O2-depletion effects

To investigate potential environmental effects in the context of carbon dioxide (CO2) leakage from Carbon Capture and Storage (CCS) schemes, the University of Nottingham ASGARD (Artificial Soil Gassing And Response Detection) facility, was used to inject CO2 into the soil in replicated open-air field plots over several seasons to measure the effects on UK crop species. However, this system lacked a way of distinguishing the concomitant effects of oxygen (O2)-depletion (occurring as a consequence of high CO2 levels in the soil). As plants are aerobic, they require O2 for functional integrity of root processes. Here a complementary laboratory system was used to specifically identify distinct CO2 and O2-depletion effects on two crop species, beetroot and wheat. Parameters measured (photosynthetic rate, transpiration rate, stomatal conductance and biomass) between CO2-gassed, nitrogen (N2)-gassed (O2-depletion control) and non-gassed control plants showed distinct differences in response to CO2 gassing and O2-depletion. Differences between field and laboratory studies illustrate effects of variable meteorological conditions in the field, whilst more stable laboratory conditions show differences between crop species. Results show that the interactions of these two stresses (very high soil CO2 and O2 depletion) on crop physiology are discrete and complex.

A PSO-based Optimization of a fuzzy-based MPPT controller for a photovoltaic pumping system used for irrigation of greenhouses

The main asset of this paper is among the uses of fuzzy logic in the engineering sector and especially in the renewable energies as a large alternate of fossil energies, in this paper a PSO-based optimization is used to find the optimal scaling parameters, of a fuzzy logic-based MPPT controller, that maximize the efficiency of a photovoltaic pumping system. The tuning of input and output parameters are of direct effect on the power that flows from the photovoltaic source to the load. In order to see concrete results, the PV system is used for irrigation of greenhouses in Laghouat, Algeria. The performances of the proposed PSO-based fuzzy controller are compared with those obtained using fuzzy logic and P&O controllers under variations of meteorological conditions. The simulation results proved a good robustness performance of the proposed Fuzzy based PSO controller over the other regarding the gained solar energy and the daily pumped water.

Effects of wet deposition on the abundance and size distribution of black carbon in East Asia

AbstractAn improved understanding of the variations in the mass concentration and size distribution of black carbon (BC) in the free troposphere (FT) over East Asia, where BC emissions are very high, is needed to reliably estimate the radiative forcing of BC in climate models. We measured these parameters and the carbon monoxide (CO) concentration by conducting the Aerosol Radiative Forcing in East Asia (A‐FORCE) 2013W aircraft campaign in East Asia in winter 2013 and compared these data with measurements made in the same region in spring 2009. The median BC concentrations in the FT originating from North China (NC) and South China (SC) showed different seasonal variations, which were primarily caused by variations in meteorological conditions. CO concentrations above the background were much higher in SC than in NC in both seasons, suggesting a more active upward transport of CO. In SC, precipitation greatly increased from winter to spring, leading to an increased wet deposition of BC. As a result, the median BC concentration in the FT was highest in SC air in winter. This season and region were optimal for the effective transport of BC from the planetary boundary layer to the FT. The count median diameters of the BC size distributions generally decreased with altitude via wet removal during upward transport. The altitude dependence of the BC size distributions was similar in winter and spring, in accord with the similarity in the BC mixing state. The observed BC concentrations and microphysical properties will be useful for evaluating the performance of climate models.

Quantitative Evaluation of an Air-monitoring Network Using Atmospheric Transport Modeling and Frequency of Detection Methods

A methodology has been developed to quantify the performance of an air-monitoring network in terms of frequency of detection. Frequency of detection is defined as the fraction of "events" that result in a detection at either a single sampler or network of samplers. An "event" is defined as a release to the atmosphere of a specified amount of activity over a finite duration that begins on a given day and hour of the year. The methodology uses an atmospheric transport model to predict air concentrations of radionuclides at the samplers for a given release time and duration. Another metric of interest determined by the methodology is called the network intensity, which is defined as the fraction of samplers in the network that have a positive detection for a given event. The frequency of detection methodology allows for evaluation of short-term releases that include effects of short-term variability in meteorological conditions. The methodology was tested using the U.S. Department of Energy Idaho National Laboratory Site ambient air-monitoring network consisting of 37 low-volume air samplers in 31 different locations covering a 17,630 km region. Releases from six major facilities distributed over an area of 1,435 km were modeled and included three stack sources and eight ground-level sources. A Lagrangian Puff air dispersion model (CALPUFF) was used to model atmospheric transport. The model was validated using historical Sb releases and measurements. Relevant 1-wk release quantities from each emission source were calculated based on a dose of 1.9×10 mSv at a public receptor (0.01 mSv assuming release persists over a year). Important radionuclides were Am, Cs, Pu, Pu, Sr, and tritium. Results show the detection frequency was over 97.5% for the entire network considering all sources and radionuclides. Network intensity results ranged from 3.75% to 62.7%. Evaluation of individual samplers indicated some samplers were poorly located and added little to the overall effectiveness of the network. Using the frequency of detection methods, alternative sampler placements were simulated that could substantially improve the performance and efficiency of the network.

High-Resolution Dynamical Downscaling of ERA-Interim Using the WRF Regional Climate Model for the Area of Poland. Part 1: Model Configuration and Statistical Evaluation for the 1981\u20132010 Period

In this work, we present the results of high-resolution dynamical downscaling of air temperature, relative humidity, wind speed and direction, for the area of Poland, with the Weather Research and Forecasting (WRF) model. The model is configured using three nested domains, with spatial resolution of 45 km × 45 km, 15 km × 15 km and 5 km × 5 km. The ERA-Interim database is used for boundary conditions. The results are evaluated by comparison with station measurements for the period 1981–2010. The model is capable of reproducing the main climatological features of the study area. The results are in very close agreement with the measurements, especially for the air temperature. For all four meteorological variables, the model performance captures seasonal and daily cycles. For the air temperature and winter season, the model underestimates the measurements. For summer, the model shows higher values, compared with the measurements. The opposite is the case for relative humidity. There is a strong diurnal pattern in mean error, which changes seasonally. The agreement with the measurements is worse for the seashore and mountain areas, which suggests that the 5 km × 5 km grid might still have an insufficient spatial resolution. There is no statistically significant temporal trend in the model performance. The larger year-to-year changes in the model performance, e.g. for the years 1982 and 2010 for the air temperature should therefore be linked with the natural variability of meteorological conditions.

Effects of the expansion of vascular plants in Sphagnum-dominated bog on evapotranspiration

Plant succession triggered by drainage, which results in the expansion or invasion of vascular plants, has been reported from many peatlands. However, the effects of the vascular plant's expansion on evapotranspiration (ET), which is a key component of the water balance of ombrotophic bog, are still contradictory. To investigate the effects, ET was measured at a Sphagnum-dominated bog and an adjacent transition peatland dominated by Sasa, dwarf bamboo, in Hokkaido Island, northern Japan, using the eddy covariance technique during the four growing seasons from 2007 through 2010. Cumulative gap-filled ET during a snow-free period of 6.5 months was 362 (2008) and 374mm (2010) at the Sphagnum site and 300 (2008) and 372mm (2010) at the Sasa site. In the mid-growing season (late June to mid-September) with the highest leaf area index (LAI) at the Sasa site, ET was 2.14±0.03 (mean±1 standard deviation of the four years) and 1.92±0.19mmd−1, respectively, at the Sphagnum and Sasa sites. ET was smaller at the Sasa site, except for 2010 with an unusual hot wet summer; mean air temperature and precipitation were higher than their 30-year normal values by 1.75°C and 172mm, respectively. At the Sphagnum site, ET was stable despite such interannual variation in meteorological conditions. However, ET increased significantly at the Sasa site in 2010 probably because of LAI increase due to the enhanced growth of Sasa plants. The ET increase at the Sasa site suggests that ET will increase at the Sasa-dominated area, if the future warming environment accompanies more precipitation.

The effects of habitat, climate, and Barred Owls on long-term demography of Northern Spotted Owls

ABSTRACT Estimates of species' vital rates and an understanding of the factors affecting those parameters over time and space can provide crucial information for management and conservation. We used mark–recapture, reproductive output, and territory occupancy data collected during 1985–2013 to evaluate population processes of Northern Spotted Owls (Strix occidentalis caurina) in 11 study areas in Washington, Oregon, and northern California, USA. We estimated apparent survival, fecundity, recruitment, rate of population change, and local extinction and colonization rates, and investigated relationships between these parameters and the amount of suitable habitat, local and regional variation in meteorological conditions, and competition with Barred Owls (Strix varia). Data were analyzed for each area separately and in a meta-analysis of all areas combined, following a strict protocol for data collection, preparation, and analysis. We used mixed effects linear models for analyses of fecundity, Cormack-Jolly-...

Black Carbon aerosol measurements and simulation in two cities in south-west Spain

Abstract Black carbon (BC) has been simulated for south-west Spain with the air quality model CAMx driven by the MM5 meteorological model, with a spatial resolution of 2 km × 2 km and a temporal resolution of 1 h. The simulation results were evaluated against hourly equivalent black carbon (EBC) concentrations obtained in the cities of Seville and Huelva for a winter period (January 2013) and a summer period (June 2013). A large seasonal variability was observed in PM 2.5 EBC concentration in the two cities, with higher concentrations in wintertime; summertime EBC concentrations were typically less than half those of the wintertime. The model captured the large diurnal, seasonal and day to day variability in these urban areas, mean biases ranged between −0.14 and 0.07 μg m −3 in winter and between 0.01 and 0.29 μg m −3 in summer while hourly PM 2.5 EBC observations ranged between 0.03 μg m −3 to 10.9 μg m −3 . The diurnal variation in EBC concentrations was bimodal, with a morning and evening peak. However, the EBC evening peak was much smaller in summer than in winter. The modelling analysis demonstrates that the seasonal and day to day variability in EBC concentration in these urban areas is primarily driven by the variation in meteorological conditions. An evaluation of the role of regional versus local contributions to EBC concentrations indicates that in the medium size city of Seville, local on-road sources are dominant, whereas in the small size city of Huelva, local as well as regional sources produce a similar contribution. Considering the large diesel share of the vehicle fleet in Spain (currently ∼ 56%), we conclude that continued reduction of BC from diesel on-road sources in these urban areas is indeed a priority, and we suggest that targeted mitigation strategies, for example reducing the heaviest emitters in wintertime, would yield the greatest benefits.

Novel Design and Simulation of a Solar Air-Conditioning System with Desiccant Dehumidification and Adsorption Refrigeration

The work deals with the design and the functioning simulation of a novel solar air-conditioning system. The new design of the system is developed with two key stages: multi-bed dehumidifier system that ensures a regular dehumidification, and an adsorption chiller that increases the energetic performance of the system. Three operation modes (summer with dehumidification, summer without dehumidification and winter modes) are detailed for the proposed solar air-conditioning system. The simulation of the functioning of the designed system was carried out, under variable meteorological conditions, in order to foresee the energetic performance and predict the temperature range ensuring the sense of well-being.

Effect of road blockages on local air pollution during the Hong Kong protests and its implications for air quality management

Roadside air quality in urban areas is largely affected by the traffic emissions. Changes in emissions and transport control policy are often assumed to yield benefits in air quality, but have often not always been effective in producing perceptible improvements due to the complexity of meteorological conditions. This study evaluates the air quality before, during and after a temporary roadway blockage event in Hong Kong that took place during Hong Kong protests from late September to mid-December, 2014. The local regulatory air quality monitoring data from both roadside and general ambient stations were used to assess the impact of roadway blockages on the air quality. There was a public perception of improved air quality, but analysis of the data shows the changes can be difficult to discern. This study showed some benefits deriving from road blockages on the local air quality, but the impact was not always apparent because of seasonal variation in meteorological conditions and synoptic transport of pollutants. The finding suggests care is required before making policy changes based on claimed benefits of shifting transport routes. The study highlights the needs to remove seasonal and meteorological change when examining air pollution data to develop strategies to improve air quality.

Concomitant evaluation of atmospheric levels of polychlorinated biphenyls, organochlorine pesticides, and polycyclic aromatic hydrocarbons in Strasbourg (France) using pine needle passive samplers.

In this study, pine needles were used as cost-effective and reliable passive bio-monitors to concomitantly evaluate atmospheric concentrations of three classes of persistent organic pollutants, polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), and polycyclic aromatic hydrocarbons (PAHs). The extraction of persistent organic pollutants (POPs) from needle samples was performed. Eleven PCBs, 11 OCPs, and 15 PAHs were detected and followed through time in needle samples from three sites in the Strasbourg region. The urban and rural sites were more exposed to PCBs than the suburban site. The highest concentration of PCBs was found at the urban site, but the largest number of congeners (10) was detected at the rural site. PCB 189 and 156 were the predominant congeners in the rural site and PCB 70 in the urban site. For OCPs, the rural site displayed the highest concentrations (up to 22.9 ng g(-1)) and number of compounds investigated (9). The high concentration of γ- and β-hexachlorocyclohexane (HCH) at that time in the urban site was the reason for this result. γ- and β-HCH were the two predominant compounds in all samples. The suburban and urban sites were the most exposed with PAHs with pyrene, phenanthrene, and acenaphthene being the three predominant compounds in these sites. No specific trend in terms of time was apparent for PCBs and OCPs. However, higher concentrations were detected for some compounds in the first sampling, especially for PAHs, and this is attributed to variations in meteorological conditions (e.g., temperature, wind, rain) and variable inputs from both identified and unidentified sources.

Time-series models to quantify short-term effects of meteorological conditions on bumblebee forager activity in agricultural landscapes

The decline of bumblebees in Europe has been linked primarily to agricultural inten- sification, although climate change also has the potential to disrupt plant-pollinator interactions, partly through an increased frequency of extreme short-term weather events. There have been few attempts to use time-series models to determine meteoro- logical variables affecting forager activity at hourly time periods over several months. 2 Time-series models require large datasets to be reliable. We describe the use of infrared detectors at nest entrances to record forager exits/returns from 36 captive colonies of Bombus terrestris audax on a mixed farm in northern England, recording over a 78-day period. 3 Over 1.73 million individual records of forager activity were obtained. These were aggregated into 1872 hourly blocks and analyzed with autoregressive time-series models that used nine meteorological factors as explanatory variables. 4 Forager activity was positively linked to air temperature and solar elevation, and negatively associated with rainfall, humidity and wind-speed. The effects of increased variability in meteorological conditions are considered in the context of these results. The time-series models that we describe will be useful in future analyses of the large datasets of foraging behaviour that are becoming available through new technologies such as radio-frequency identification and video tracking.

Satellite Observed Aerosol Optical Thickness and Trend around Megacities in the Coastal Zone

Nearly 30-year aerosol optical thickness (AOT) climate data record (CDR) derived from the operational satellite observations of National Ocean and Atmospheric Administration (NOAA) Advanced Very High Resolution Radiometer (AVHRR) is used to study the AOT trends over seventeen megacities in the coast zone (MCCZ). Linear trends are derived from monthly and seasonal mean AOT in the past three decades and used in the analysis. The results indicate the following: (1) AOT around a MCCZ in fast developing countries has relatively high value and a positive trend with a confidence level generally above 95%; (2) AOT around a MCCZ in industrialized countries has relatively low value and a negative trend with a confidence level generally above 95%; (3) AOT values and their trends show distinct seasonal variations in MCCZ, which can be explained somewhat by the seasonal variations of meteorological conditions. AOT trend is an effective index for examining the efficacy of air pollution control policies implemented for these megacities.

Web tools concerning performance analysis and planning support for solar energy plants starting from remotely sensed optical images

We present innovative web tools, developed also in the frame of the FP7 ENDORSE (ENergy DOwnstReam SErvices) project, for the performance analysis and the support in planning of solar energy plants (PV, CSP, CPV). These services are based on the combination between the detailed physical model of each part of the plants and the near real-time satellite remote sensing of incident solar irradiance.Starting from the solar Global Horizontal Irradiance (GHI) data provided by the Monitoring Atmospheric Composition and Climate (GMES-MACC) Core Service and based on the elaboration of Meteosat Second Generation (MSG) satellite optical imagery, the Global Tilted Irradiance (GTI) or the Beam Normal Irradiance (BNI) incident on plant's solar PV panels (or solar receivers for CSP or CPV) is calculated. Combining these parameters with the model of the solar power plant, using also air temperature values, we can assess in near-real-time the daily evolution of the alternate current (AC) power produced by the plant. We are therefore able to compare this satellite-based AC power yield with the actually measured one and, consequently, to readily detect any possible malfunctions and to evaluate the performances of the plant (so-called “Controller” service). Besides, the same method can be applied to satellite-based averaged environmental data (solar irradiance and air temperature) in order to provide a Return on Investment analysis in support to the planning of new solar energy plants (so-called “Planner” service).This method has been successfully applied to three test solar plants (in North, Centre and South Italy respectively) and it has been validated by comparing satellite-based and in-situ measured hourly AC power data for several months in 2013 and 2014. The results show a good accuracy: the overall Normalized Bias (NB) is −0.41%, the overall Normalized Mean Absolute Error (NMAE) is 4.90%, the Normalized Root Mean Square Error (NRMSE) is 7.66% and the overall Correlation Coefficient (CC) is 0.9538. The maximum value of the Normalized Absolute Error (NAE) is about 30% and occurs for time periods with highly variable meteorological conditions.

Estimating the energy saving potential from carrying out adjustment works in heat supply systems on the basis of modeling their thermal-hydraulic operating modes

An example of determining the economic effect from carrying out adjustment works based on the results of calculating the thermal-hydraulic operating modes of heat supply systems with the use of mathematical models implemented in the Angara information-and-computation system is presented. The models take into account the dynamic characteristics of operating modes, variation of meteorological conditions, disturbing and control inputs applied to the system, and the real cost spent for producing energy and distributing its flows. It is shown that considerable potential for saving energy resources lies in setting up rational distribution of heat flows over the system. An important thing in this regard is that proper organization of the heat supply system operating modes and development of adjustment works are only possible on the basis of carrying out preliminary calculations.

Individual repeatability in timing and spatial flexibility of migration routes of trans-Saharan migratory raptors

Abstract Satellite-tracking technology has allowed scientists to make a quantum leap in the field of migration ecology. Nowadays, the basic description of migratory routes of many species of birds has been reported. However, the investigation of bird migration at individual level (i.e. repeatability in migratory routes and timing) still remains seldom explored. Here, we investigated repeated migratory trips of a trans-Saharan endangered migratory raptor, the Egyptian Vulture Neophron percnopterus, tracked by GPS satellite telemetry. We compared between- and within-individual variation in migratory routes and timing in order to assess the degree of repeatability (or conversely, the flexibility) in migration. To this end, we analysed a dataset of 48 trips (23 springs and 25 autumns) recorded for six adult birds during 2007-2013. Our results showed consistent migration timing at the individual level, both in spring and autumn. Interestingly, there was a high degree of flexibility in the routes followed by the same individual in different years, probably due to variations in meteorological conditions. Contrary to expectations of a faster migration in spring than in autumn owing to a time-minimization strategy for breeding, birds spent less time in autumn migration (13 ± 2 days, range = 9–18 d) than in spring migration (19 ± 3 days, range = 13–26 d), which can be explained by differences in environmental conditions en route. Egyptian vultures showed a consistent clockwise loop migration through western Africa, following more easterly routes in autumn than in spring. Finally, our results provide supporting evidence of low phenotypic plasticity in timing of migration (i.e. strong endogenous control of migration) and high flexibility in routes.

Determining the high variability of pCO2 and pO2 in the littoral zone of a subtropical coastal lake

The aquatic metabolism comprises production and mineralization of organic matter through biological processes, such as primary production and respiration that can be estimated by gases concentration in the water column. AIM: The study aimed to assess the temporal variability of pCO2 and pO2 in the littoral zone of a subtropical coastal lake. Our hypotheses are i) high variability in meteorological conditions, such as temperature and light, drive the high variability in pCO2 and pO2, and ii) the lake is permanently heterotrophic due to the low phosphorus concentration. METHODS: We estimated pCO2 from pH-alkalinity method, and pO2 from dissolved oxygen concentration and water temperature measured in free-water during 24 hours in the autumn, winter, spring and summer. RESULTS: Our findings showed that limnological variables had low temporal variability, while the meteorological variables and pCO2 presented a high coefficient of variation, which is representative of each climatic season. In autumn and winter, it was recorded that the lake was supersaturated in CO2 relative to the atmosphere, while in spring and summer CO2 concentration was below the concentration found in the atmosphere. Over 24 hours, pCO2 also showed high variability, with autumn presenting higher concentration during the night when compared to daytime. Water temperature and chlorophyll a were negatively correlated with pCO2, while pO2 was positively correlated with wind and light. CONCLUSION: Agreeing with our first hypothesis, pCO2 showed an expressive temporal variation in a subtropical lake associated to the high variability in meteorological conditions. On the other hand, our second hypothesis was not confirmed, since Peri Lake exported CO2 to the atmosphere in some periods and in others, CO2 was removed from the atmosphere.

Temporal variability in groundwater and surface water quality in humid agricultural catchments; driving processes and consequences for regional water quality monitoring

Considering the large temporal variability in surface water quality is essential for adequate water quality policy and management. Neglecting these dynamics may easily lead to decreased effectiveness of measures to improve water quality and to inefficient water quality monitoring. The objective of this paper is to summarise our understanding of temporal variability in surface water and upper groundwater quality and to discuss the consequences and opportunities for regional water quality monitoring. In regional monitoring networks, measurement frequencies are typically too low to capture the short-term temporal variations in solute concentrations. This causes large uncertainty in the assessment of (trends in) average concentrations and contaminant loads. The most important driver for short-term variations in water quality in most catchments is the variability in meteorological conditions, which induces changes in the relative discharge contributions of water from different flow routes and different chemical compositions. Various options exist for dealing with the transient behavior of water quality in regional water quality monitoring. Estimates of average concentrations and loads from low-frequency concentration data can be improved by using the explanatory strength of commonly available measurements of quantitative hydrological data like precipitation, discharge, and groundwater levels. This paper provides examples of the relationship between water quality and explanatory variables in conceptual, statistical, or process-based models. Another strategy for dealing with short-term variability in water quality monitoring is to measure long-term average solute concentrations using passive samplers. Similarly, on-site auto analyzers and ion specific electrodes provide opportunities for continuous water quality measurements.

Interannual variability of tropospheric NO2 column over central Europe — observations from SCIAMACHY and GEM-AQ model simulations

Spatial and temporal variability of NO2 tropospheric column over Europe was analyzed for a 3 year period (2008–2010) based on monthly average observations from SCIAMACHY and the GEM-AQ model results. The GEM-AQ model was run in a global variable configuration with a resolution of ∼15 km over Central Europe. Spatial averaged time series were calculated for two selected regions in Western and Central Europe in order to assess the seasonal and interannual variability of the tropospheric NO2. The spatial pattern is similar near large emission sources for consecutive years. However, in remote regions there are differences due to interannual variability of meteorological conditions. Highest tropospheric NO2 column values (over 150 × 1015 molecules/cm2) were persistent over the Benelux and over most of the European agglomerations. The general agreement between modelled and observed NO2 column is good. In the remote areas, the modelled NO2 column shows weaker gradients than the observed field.

On Thermo-Hydro-Mechanical (THM) Fatigue Damage of Historical Stone Buildings

The efficient conservation, restoration and protection of stone historical buildings could not be dissociated from the researches of mechanism of stone decays. While various mechanisms of stone degradations are considered and studied in previous studies, in this paper is focused on the cumulative damage modeling of wall stones due to the fatigue induced from quotidian fluctuations of thermal and hydric conditions. The thermoporomechanics theory of partially saturated media is used to describe the behavior of stone wall and its interaction with climatic conditions. Further, the effective stress concept firstly introduced by Terzaghi is extended for partially saturated media providing a quite powerful tool for design and analysis [. The behavior of a typical stone wall from Chambord castle (Center region of France) is then simulated, taking into account the heterogeneity of the stone-mortar contacts. The climatic conditions are introduced in the model as boundary conditions. The records of temperature and humidity from meteorological stations close to castle are used to establish time-variation of condition with a time resolution of 6 hours. From performed numerical analyses, it is shown that variation of temperature and relative humidity leads to the variation and fluctuation of effective stress in the stone, more intensively on the outdoor. The contact of stone with mortar is a natural stress concentration center, but even there the stress is much lower than tensile strength of the white tuffeau stone. The fatigue of the stone due to the stress fluctuation induced by the variations of meteorological conditions seems to be a major factor of stone degradation. A model is used to assess the cumulative damage of the stone wall as a function of the time.