Dry Summer Research Articles

The Use of Double-Skin Façades to Improve the Energy Consumption of High-Rise Office Buildings in a Mediterranean Climate (Csa)

Engineers use double-skin façades (DSF) to lower the energy consumption of buildings as they can potentially control incoming wind speeds and the amount of solar heat gain. The purpose of this present study was to (1) evaluate the use of DSFs, (2) its efficacy in improving the energy performance of high-rise office buildings in the hot, dry summer climate of the Mediterranean, and (3) to develop an optimum DSF model for this climate based on industry standards and recommendations for high-performance DSF parameters. In order to determine the efficiency of DSFs, two distinct variables, building orientation and the number of DSFs used, were taken into consideration. This study adopted an experimental (generate and test) research design and used Autodesk® Ecotect® Analysis software to develop computer simulations with which to assess 15 single façades, juxtaposed façades, three façades, and four façades on cardinal orientations. The recorded energy consumption and savings were then compared with that of the reference model. The results indicated that the three DSF model, i.e., the S14 model, reduced energy consumption during heating by 28% and by 53.5% when cooling a high-rise office building located in the hot, dry summer climate of the Mediterranean (Csa).

Investigating the Granulometric Distribution of Fluvial Sediments through the Hybrid Technique: Case Study of the Baganza River (Italy)

Sediment characterization is a key parameter to understand the geomorphological attributes of a catchment (i.e., assessing the variability of the sediment transport capacity and surface roughness of a hydraulic channel). This assessment can be performed in several ways, for instance, through numerous sampling techniques (i.e., pebble count and zig-zag methods). Sediment sampling using manual sieving inside a laboratory is a hectic process as it requires ample time and physical effort, particularly when the scale of interest is at the catchment level. In order to find the granulometric distribution of some sections of the Baganza streambed (northern Italy), in order to carry out analysis at the catchment scale, a hybrid technique (a combination of the conventional and photogrammetric method) is introduced. Different grain size distribution curves (GSDs) obtained from the image processing technique using Digital Gravelometer software and traditional sediment sieve analysis (sieve-by-weight method) were compared. Sediment sampling was limited to sections of the streambed that were visible during lower flows in the dry summer season. Sediment samples including fine soil fraction, were collected up to a depth of 30 cm, although the exposed areas behaved as gravels and cobble bars. The adopted hybrid technique approach for the characterization of fluvial sediments is desirable in order to accommodate the full range of particle sizes inside the riverbed. Digital photography was performed at ten different cross sections, along the longitudinal profile of the 30 km long reach of the Baganza River, to examine the sediment distribution, grading, and representative particle sizes (D10, D50, D90) at each of the respective cross sections. A comparison of the photogrammetric method and traditional sieve analysis revealed strong agreement in coarser segments of the grain size distributions, but it was deficient in the finer part (<2 mm) due to the shielding effect produced by bigger particles. However, the adopted hybrid technique appears to be quite efficient and promising in determining the GSD by reducing the costs and the sediment sample collection time in the field.

The Character and Changing Frequency of Extreme California Fire Weather

AbstractFive of California's 10 largest wildfires occurred in 2020, with the largest complex exceeding the previous largest by more than 100%. The year follows a decade containing extraordinary fire activity. Previous trend investigations focused on changes in human activities and atmospheric thermodynamics, while the impacts of changing atmospheric dynamics are largely unknown. Here, we identify weather types (WTs) associated with historically large daily burned areas in eight Californian regions. These WTs characterize dominant fire weather regimes varying in fire behavior types (plume‐driven vs. wind‐driven fires) and seasonality. Most of the strongly large‐scale forced WTs such as Santa Ana and Diablo events increased in frequency during the 20th century particularly in the San Diego and Bay Area regions. These changes are likely not anthropogenically caused and the frequency of such events is projected to decrease under continuing climate change. However, significant future increases are found for WTs associated with thermal‐low‐pressure systems along the California coast and in the Sierra west region. These increases in southern California are mainly due to increasing greenhouse‐gas forcing and arise from the larger ocean‐land temperature gradient while aerosol forcing changes are driving most of the increased frequency in central and northern California due to a reduction of relative humidity over land and a strengthening of low‐pressure anomalies over the coast. These WT frequency changes could permit more weather favorable for large fire growth in summer and less in fall, further enhancing the risk of catastrophic fires due to hotter and drier summers in future climates.

Climate Insurance for Agriculture in Europe: On the Merits of Smart Contracts and Distributed Ledger Technologies

Climate insurance has become a crucial issue due to the increasing number of climate-related catastrophic events and the associated losses for the economy in general and insurance companies in particular. The extremely hot and dry summers of 2018 and 2019 in some European countries highlighted existing weaknesses in European agricultural insurance mechanisms, with farmers having to wait for months before compensation payments could be made. Our paper compares features of yield-based insurance and index-based insurance (IBI) in agriculture in the light of new developments and trends in information technology (IT). The results show that applying Distributed Ledger Technologies (DLT) in combination with IBI could not only resolve existing problems but also facilitate the development of innovative risk management tools under the EU’s Common Agricultural Policy (CAP) post-2020 reform.

Variations of PM2.5 sources in the context of meteorology and seasonality at an urban street canyon in Southwest Germany

In order to assess the factors controlling urban air pollution, we characterized fine particulate matter (PM2.5) at an urban street canyon in southwest Germany, in summer 2019 and winter 2020. The average mass concentration of PM2.5 was higher in dry and hot summer (7.0 ± 3.5 μg m−3) than in cold and humid winter (5.8 ± 2.8 μg m−3) with frequent wet scavenging. The non-refractory PM2.5 (NR-PM2.5) measured with an aerosol mass spectrometer (AMS) plus black carbon (BC) mostly consists of organic aerosol (OA) with 60% in summer and 44% in winter. The contributions of sulfate to NR-PM2.5 plus BC was higher in summer (18%) than in winter (13%), while that of nitrate was lower in summer (6%) than in winter (22%). During the entire measurement periods in both seasons, relatively flat diurnal variations of sulfate were found, suggesting that it was associated with regional transport. However, occasionally rapid increase of sulfate can be caused by the transport of upwind industrial sources and enhanced vertical mixing processes. Nitrate showed a peak at morning rush hours related to traffic emissions, and then subsequently decreased by evaporation processes during daytime with higher temperature. Positive matrix factorization analysis revealed that the total OA was dominated by secondary organic aerosol (SOA) over the primary traffic emissions with ∼82% in summer and ∼48% in winter. A detailed analysis of two pollution episodes clearly demonstrated the impact of meteorological conditions on secondary aerosol formation and accumulation. A summertime heatwave episode showed high contributions of SOA to PM2.5 mass, which formed locally through daytime photochemical oxidation as well as nighttime chemistry of biogenic precursors. A wintertime transitional episode occurred with significant shift from relatively warm and humid to cold and dry conditions. The fast formation of sulfate, nitrate, ammonium and SOA were found under the warm and humid period after receiving a local industrial emission plume. The cold and dry period was influenced by various sources including long-range transport of Saharan dust and anthropogenic emissions in central Europe. This study highlights the variations of urban PM2.5 sources under certain meteorological conditions such as summer heatwave and humid winter, which are expected high occurrence in future. Our results provide the implication on actual needs of mitigation actions to these pollution episodes in less-polluted western Europe cities.

Impact of ocean-atmosphere coupling on present and future Köppen-Geiger climate classification in Europe

The effect of air-sea coupling in the simulation of the European climate is assessed through a climate type classification that uses surface temperature and precipitation from a regional atmosphere-ocean coupled model and from its atmospheric component. The atmospheric setup in both models is the same, differing only in the representation of the oceanic fields. The simulations cover the present and future-time climate under the RCP8.5 CMIP5 scenario. Climate type distributions obtained from both coupled and uncoupled simulations are similar to those obtained from ERA5 for the 1976–2005 period. Both models simulate colder climate types for present-time in southern and northeastern regions compared to ERA5, possibly due to a weaker influence of the Atlantic circulation, and drier climate types in some western Mediterranean areas. Also, for present-time coupling leads to more humid winters (relatively drier summers) in some zones of north Spain and south France, and drier climates in some western Mediterranean spots. Based on simulations with these models under the RCP8.5 scenario, we find that by the end of the 21st century (2070–2099) the climate type distribution changes in more than 50% of the domain. While both models project the reduction of regions with cold climate types and the expansion of those with hot summers and hot arid climate types, these changes affect a larger area in the coupled simulation. These differences may be related to a drier signal in the coupled simulation, especially during summer, due to the influence of colder surface water in the North Atlantic Ocean and the Mediterranean Sea. Using a climate classification to evaluate the annual cycles of the simulated temperature and precipitation data provides a novel insight into the impact of air-ocean coupling on the representation of the climate, and consequently into the simulated impact on ecosystems and human activities in Europe.

Climate change will increase aflatoxin presence in US Corn

The impacts of climate change on agricultural production are a global concern and have already begun to occur (Kawasaki 2018 Am. J. Agric. Econ. 101 172–92; Ortiz-Bobea et al 2021 Nat. Clim. Change 11 306–12), with major drivers including warmer temperatures and the occurrence of extreme weather events (Lobell and Field 2007 Environ. Res. Lett. 2 014002; Challinor et al 2014 Nat. Clim. Change 4 287; Rosenzweig et al 2001 Glob. Change Hum. Health 2 90–104; Schlenker and Roberts 2009 Proc. Natl Acad. Sci. USA 106 15594–8; Lobell et al 2014 Science 344 516–9; Ortiz-Bobea et al 2019 Environ. Res. Lett. 14 064003). An important dimension of the climate change-crop yield relationship that has often been overlooked in the empirical literature is the influence that warming temperatures can have on plant damage arriving through biotic channels, such as pest infestation or fungal infection (Rosenzweig et al 2001 Glob. Change Hum. Health 2 90–104). Aflatoxins are carcinogenic chemicals produced by the fungi Aspergillus flavus and A. parasiticus, which commonly infect food crops. Currently, in the United States, aflatoxin is a perennial contaminant in corn grown in the South, but rare in the Corn Belt and northern states. Climate change may expand aflatoxin’s geographical prevalence, however; because hot, dry summers promote aflatoxin accumulation. Here we model aflatoxin risk as a function of corn plant growth stages and weather to predict US regions with high aflatoxin risk in 2031–2040, based on 16 climate change models. Our results suggest that over 89.5% of corn-growing counties in 15 states, including the Corn Belt, will experience increased aflatoxin contamination in 2031–2040 compared to 2011–2020. Interestingly, the results are spatially heterogeneous and include several southern counties expected to have lower aflatoxin risk, because the causative fungi become inactivated at very high temperatures.

Mid-latitude alluvial and hydroclimatic changes during the Paleocene–Eocene Thermal Maximum as recorded in the Tremp-Graus Basin, Spain

A short episode (~170 kyr) of extremely high global temperatures that occurred ~56 Ma, known as the Paleocene–Eocene Thermal Maximum, is widely considered an ancient analogue of the ongoing anthropogenic warming. This ancient hyperthermal event consisted of three phases, onset, core and recovery, which are respectively represented in the mid-latitude south Pyrenean Tremp-Graus Basin by three successive terrestrial units, the Claret Conglomerate, the Yellowish Soils and the Gypsum-rich Unit, each of them recording a different sedimentary response to evolving climatic and hydrological regimes. The Claret Conglomerate is mainly made up of calcareous conglomerates and is acknowledged to record an abrupt hydrological change during the onset phase. This unit most likely formed in an alluvial megafan, an interpretation here reinforced with new architectural information and by comparison with naturally occurring small-scale fan-like accumulations. Assuming the similarity between the onset of the Paleocene–Eocene Thermal Maximum and the anthropogenic warming, recent hydrological and meteorological data from mid-latitude Spain were compiled for comparison purposes. This comparison concurs with published modelling results about hydroclimate changes in the Pyrenees during the hyperthermal event, postulating an enhancement of seasonal contrast with augmented frequency and intensity of floods but no significant change in total rain. Furthermore, the comparison suggests that the Claret Conglomerate accumulated during extreme rainfall episodes that mainly occurred in autumn. The Yellowish Soils are mostly composed of silty marls with ubiquitous small-sized carbonate nodules and intercalated calcarenites. The marls were deposited in floodplains and the calcarenites in point bars and crevasse splays of meandering rivers. The scarcity of conglomerates entails a near absence of strong currents, and the carbonate nodules perennial or seasonal arid conditions. These nodules occur within cumulate palaeosols, the development of which required regular sedimentary increments during inundations on the floodplains. Sedimentation rates of siliciclastic material on the floodplains increased significantly during the core of the hyperthermal event, as well as at river outlets in coastal settings, which shows that erosion was accelerated and rules out the occurrence of protective, dense vegetation. Combined, these characteristics suggest persistent very dry summers, but a smooth wet season without intense precipitation events. Lastly, the profusion of gypsum in the youngest unit is clear proof of an arid climate during the recovery of the hyperthermal event. In essence, the studied deposits provide a unique window into the sequence of hydroclimatic change during the rise, peak and decline of an ancient global warming event in a mid-latitude terrestrial setting, against which ongoing climate-change data and future projections can be compared.

EPPO Datasheet: Naupactus xanthographus

EPPO Datasheet: <i>Naupactus xanthographus</i>

Recent decrease in summer precipitation over the Iberian Peninsula closely links to reduction in local moisture recycling

Abstract. The inherently dry summer climate of the Iberian Peninsula (IP) is undergoing drought exacerbated by more intense warming and reduced precipitation. Although many studies have studied changes in summer climate factors, it is still unclear how the changes in moisture contribution from the sources lead to the decrease in summer precipitation. This study investigates the differences in the IP precipitationshed from 1980 to 1997 and 1998 to 2019 using the Water Accounting Model-2layers with ERA5 data, and assesses the role of local moisture recycling and external moisture in reducing summer precipitation. Our findings indicate that the moisture contributions from the local IP, and from the west and the east of the precipitationshed, contributed 1.7, 3.6 and 1.1 mm per month less precipitation after 1997 than before 1997, accounting for 26 %, 57 % and 17 % of the main source supply reduction, respectively. The significant downward trend of the IP local moisture recycling closely links to the disappearance of the wet years after 1997 as well as the decrease in local contribution in the dry years. Moreover, the feedback between the weakened local moisture recycling and the drier land surface can exacerbate the local moisture scarcity and summer drought.

Determining the hot spots and hot moments of soil N2O emissions and mineral N leaching in a mixed landscape under subtropical monsoon climatic conditions

Identification of hot spots and hot moments (HSHMs) in regard to soil nitrogen (N) losses has received public attention. Soil nitrous oxide (N2O) emissions and mineral N leaching under varied annual precipitation were simulated with the DayCent model in a mixed landscape (tea garden, bamboo forest and coniferous and broad-leaved mixed forests). Their HSHMs were further quantified using the 3rd quartile value of all data as the baseline. Results showed that the hot moments of soil N2O emissions were the dry year, summer, and months with high air temperature (July to September) and months after fertilization (April or May) at inter-annual, seasonal and monthly time scales, respectively. The hot moments of mineral N leaching at these time scales were the normal year or the wet year, spring or rainy seasons after drought, and rainy months after fertilization or drought, respectively. The main factors controlling the formation of hot moments on N losses were temperature, precipitation and fertilization. In addition, the hot spots of N2O emissions and mineral N leaching in the mixed landscape were both distributed in the tea garden (TG). When the entire study area was assumed to be under the same land-use type (i.e., TG), the hot spots of these two kinds of N losses were mainly distributed in the areas with rock fragment content < 0.16 cm3 cm−3, field capacity > 0.24 cm3 cm−3, bulk density > 1.29 g cm−3, soil carbon (C)/N ratio < 13.26, and slope < 12°. These results indicated that fertilizer management, climate factors, soil properties and topography need to be comprehensively considered to alleviate the formation of HSHMs of N losses in mixed landscape mountainous areas.

Hotspots for warm and dry summers in Romania

Abstract. The combined effect of hot and dry extremes can have disastrous consequences for society, the economy, and the environment. While a significant number of studies have been conducted regarding the variability of the individual hot or dry extremes in Romania, the evaluation of the combined effect of these extremes (e.g., compound effect) is still lacking for this region. Thus, in this study, we have assessed the spatiotemporal variability and trends of hot and dry summers in Romania, between 1950 and 2020, and we have analyzed the relationship between the frequency of hot summers and the prevailing large-scale atmospheric circulation. The length, spatial extent, and frequency of heat waves (HWs) in Romania present decadal variations, with the rate of increase being accelerated after the 1990s. The smallest number of HWs was observed between 1970 and 1985, while the highest number of HWs has been recorded over the last 2 decades (i.e., 2001–2020). The hottest years, in terms of heat wave duration and frequency, were 2007, 2012, 2015, and 2019. One of the key drivers of hot summers, over our analyzed region, is the prevailing large-scale circulation, featuring an anticyclonic circulation over the central and eastern parts of Europe and enhanced atmospheric blocking activity associated with positive temperature anomalies underneath. The results from this study can help improve our understanding of the spatiotemporal variability of hot and dry summers over Romania, as well as their driving mechanisms, which might lead to a better predictability of these extreme events in the region.

The Large-Scale Effect of Forest Cover on Long-Term Streamflow Variations in Mediterranean Catchments of Central Chile

Forest ecosystems play an important role in hydrological processes as surface and subsurface runoff, as well as the storage of water at the catchment scale. Therefore, it is important to have a greater understanding of the effects of forests in the long-term water balance of Mediterranean catchments. In this sense, this study evaluates the effect of native forests, forest plantations, and the combination of both, on long-term streamflow variations in central Chile, an unusual area of Mediterranean climate characterized by a well-marked annual cycle with dry summers and wet winters. Thus, the temporal pattern of monthly streamflow was evaluated for mean flow (Qmean), maximum flow (Qmax), and minimum flow (Qmin) in 42 large-scale (&gt;200 km2) Mediterranean catchments. Each series of monthly streamflow data was QA/QC, and then evaluated using the Mann–Kendall’s non-parametric statistical test to detect temporal variations between 1994 and 2015. In addition to the previous analysis, the monthly series were grouped into wet seasons (April–September) and dry seasons (October–April), to determine if there were any significant differences within the annual hydrological cycle. The areas covered with native and forest plantations and their relative changes were evaluated for each catchment through streamflow variations and forest cover indicators. Results revealed that streamflow variations are positive and significant when more forest cover exists. The intra-catchment relationships assessed for both species revealed the significant role of native forests and mixed masses as key ecosystems for the long-term conservation of summer streamflow in Mediterranean catchments of central Chile. These findings encourage an urgent need to create highland afforestation programs on degraded areas of central Chile, to maximize water storage in a region that is quickly drying out due to unsustainable water and land use management practices and the effects of global warming.

Revisiting the cumulative effects of drought on global gross primary productivity based on new long-term series data (1982-2018).

Drought has broad and deep impacts on vegetation. Studies on the effects of drought on vegetation have been conducted over years. Recently, the cumulative effect of drought is recognized as another key factor affecting plant growth. However, global-scale studies on this phenomenon are still lacking. Thus, based on new satellite based gross primary productivity (GPP) and multi-temporal scale Standardized Precipitation Evapotranspiration Index data sets, we explored the cumulative effect duration (CED) of drought on global vegetation GPP and analyzed its variability across elevations and climatic zones. The main findings were as follows: (1) The cumulative effect of drought on GPP was widespread, with an average CED of 4.89months. (2) CED of drought on GPP varied among vegetation types. Specifically, grasslands showed the longest duration, with an average value of 5.28months, followed by shrublands (5.09months), wetlands (5.03months), croplands (4.85months), savannas (4.58months), and forestlands (4.57months). (3) CED of drought on GPP changes with climate conditions. It decreased with the decrease of precipitation in the driest month (Pdry ) and mean annual precipitation in tropical and arid climate zones, respectively. In both temperate and cold climate zones, CED of drought on GPP was shorter in areas with dry winter than that in areas with dry summer. It increased with the decrease of mean annual air temperature in tropical climate zones and decreased with the increase of summer temperature in temperate and cold climatic zones. (4) With increasing elevation, CED of drought on GPP showed a pattern of increasing (0-3000m), then decreasing (3000-5000m), and increasing again (>5000m). Our findings highlight the heterogeneity of CED of drought on GPP, owing to differences in vegetation types, long-term hydrothermal conditions, elevation, etc. The results could deepen our understanding of the effects of drought on global vegetation.

Climate change adaptation processes seen through a resilience lens: Norwegian farmers’ handling of the dry summer of 2018

Climate change and more frequent extreme weather events are expected to significantly challenge food production and food security worldwide, underlining the need for adaptation within the agricultural sector. Although Norway, as other Nordic countries, potentially benefits from higher temperatures in terms of agricultural production, adaptation will be necessary. Employing resilience as a theoretical lens, this study investigates Norwegian farmers’ handling of the dry summer of 2018, a summer that comprehensively challenged agricultural production throughout Europe. In-depth interviews revealed that farmers’ main strategy was to improve their buffer capacity to be able to ‘bounce back’ (i.e., to get ‘through’ the summer to return to a ‘normal’ situation). Informal and formal networks, access to outfield resources and governmental support played key roles in enhancing the buffer capacity. Structural changes in the agricultural sector seem to challenge future access to the resources needed to improve the buffer capacity in times of crisis. Within the current environmental, social and political framework, farms are considered resilient, and strengthening buffer capacity is reasonable. However, a higher frequency of extreme weather events may require that other capacities, such as adaptive or transformative, be improved. Thus, resilience is not a given state and independent of values but strongly context dependent. To achieve long-term resilience, climate change adaptation needs to be politically encouraged and economically supported. Farmers need flexibility to use local resources. Worries about structural changes may draw farmers’ attention away from making potentially important adaptations to climate change.

Climate Scenarios for Switzerland CH2018 – Approach and Implications

To make sound decisions in the face of climate change, government agencies, policymakers and private stakeholders require suitable climate information on local to regional scales. In Switzerland, the development of climate change scenarios is strongly linked to the climate adaptation strategy of the Confederation. The current climate scenarios for Switzerland CH2018 - released in form of six user-oriented products - were the result of an intensive collaboration between academia and administration under the umbrella of the National Centre for Climate Services (NCCS), accounting for user needs and stakeholder dialogues from the beginning. A rigorous scientific concept ensured consistency throughout the various analysis steps of the EURO-CORDEX projections and a common procedure on how to extract robust results and deal with associated uncertainties. The main results show that Switzerland’s climate will face dry summers, heavy precipitation, more hot days and snow-scarce winters. Approximately half of these changes could be alleviated by mid-century through strong global mitigation efforts. A comprehensive communication concept ensured that the results were rolled out and distilled in specific user-oriented communication measures to increase their uptake and to make them actionable. A narrative approach with four fictitious persons was used to communicate the key messages to the general public. Three years after the release, the climate scenarios have proven to be an indispensable information basis for users in climate adaptation and for downstream applications. Potential for extensions and updates has been identified since then and will shape the concept and planning of the next scenario generation in Switzerland.

Induction and potential role of summer dormancy to enhance persistence of perennial grasses under warmer climates

Abstract The persistence of perennial herbaceous species is threatened by increasing aridity. However, summer dormancy is a strategy conferring superior survival to grasses adapted to hot and dry summers. The role of temperature on the induction of summer dormancy was investigated in the perennial grass Dactylis glomerata to analyse the potential expression of this strategy under warmer climates. We tested seven populations of D. glomerata originating from Morocco to Norway across the same latitudinal gradient in a five‐site experiment. One population of the highly summer‐dormant grass Poa bulbosa was used as a reference. Plants were grown from autumn in pots under full irrigation for 1 year mostly under open‐air shelters. Heading date (ear emergence preceding flowering) was recorded and foliage senescence was assessed from end of spring until autumn. The maximum plant senescence under summer irrigation indicated the level of dormancy expression. Summer dormancy onset, release, expression and duration were modelled as a function of climatic variables. From north to south, the duration of summer dormancy of the Mediterranean populations of D. glomerata and P. bulbosa ranged from 0 to 122 days, and 79 to 200 days, respectively. P. bulbosa was always completely dormant, while dormancy expression of D. glomerata was positively correlated with the sum of temperatures from winter onset (R2 = 0.57) and with the mean of minimum temperatures in summer (R2 = 0.73). Dormancy onset, release and duration were also positively correlated with thermal time from winter onset, while the duration of summer dormancy was longer as maximum temperatures increased. Mapping the European regions with climates allowing the expression of summer dormancy in D. glomerata showed that the potentially inductive areas for this strategy may expand in parallel with increasing summer aridity under a future climate warming scenario. Synthesis. The large phenotypic variability of the expression of summer dormancy in D. glomerata was driven by temperature, suggesting that this strategy may have a greater role in higher latitudes to increase plant survival over the predicted hotter and drier summers. Leveraging this strategy for the choice and selection of suitable populations could enhance future adaptation of major perennial grasses to climate change.

A solar thermal driven ORC-VFR system employed in subtropical Mediterranean climatic building

This paper investigates the configuration of solar thermal collector driven organic Rankine cycle (ORC) utilized to power air-conditioning system of the two-story office building in Paralimni, Cyprus, through a Variable-Refrigerant-Flow (VRF) system. The reason to choose this Mediterranean climate of Paralimni, Cyprus, is due to its higher dependency on fossil fuels compared to many other countries in the EU and with a high potential of harnessing solar irradiations and demand for air-conditioning (AC) loads. This location is categorized as warm temperate zones, subtropical climates and is placed in the subcategory of Mediterranean climates with humid winters and dry summers according to climatic zone, highly demanding for air conditioning. Based on the climatic data of the study area, this system can make an effective performance. Modeling the building and estimating the AC system power consumption is carried out in the DesignBuilder. Designing the organic Rankine cycle is done with EES. A solar hot water system is designed with TRNSYS to supply the required mass flow rate of water at the desired temperature of 95 °C. In this climate, the annual surface irradiation rate is 1,793 kWh/m2 whilst the AC energy requirement of a two-story building is 7,909 kWh. The employed ORC with an internal heat exchanger is designed with a constant output rate of 3.920 kW, which delivers a total of 8,154 kWh yearly. The required heat input of the ORC is supplied by a solar hot water system, employing evacuated tube collectors. The solar system consumes a 454 kWh auxiliary heating rate per year to deliver the desired mass flow rate and outlet temperature for the ORC. As a result, the designed solar-driven ORC delivers a net of (8,154 – 454) kWh = 7,700 kWh energy each year, meaning 7,700 kWh energy saving per year, equal to 97% of VRF annual energy demand. This amount of yearly energy saving yields 2,010 USD yearly capital saving as the reward of investment in this system, and defining a 20-year project, the implementation of this solar-driven power generation system at the end of the project's lifetime would save 25,049 USD.

Effect of Climate Change on the Growth of Tree Species: Dendroclimatological Analysis

Tree ring analyses can assist in revealing the effect of gradual change in climatic variables on tree growth. Dendroclimatic analyses are of particular importance in evaluating the climate variables that affect growth significantly and in determining the relative strength of different climatic factors. In this study, we investigated the growth performance of Pinus sylvestris, Picea abies, and Pseudotsuga menziesii in northern Germany using standard dendrochronological methods. The study further analyzed tree growth responses to different climatic variables over a period of a hundred years. Both response function analysis and moving correlation analysis confirmed that the climate and growth relationship is species-specific and variable and inconsistent over time. Scots pine and Douglas fir growth were stimulated mainly by the increase in winter temperatures, particularly the January, February, and March temperatures of the current year. In contrast, Norway spruce growth was stimulated mainly by the increase in precipitation in May, June, and July and the increase in temperature in March of the current year. Climate projections for central Europe foresee an increase in temperature and a decrease in the amount of summer precipitation. In a future, warmer climate with drier summers, the growth of Norway spruce might be negatively affected.

The Establishment and Spread of a Newly Introduced Begomovirus in a Dry Tropical Environment Using Tomato Yellow Leaf Curl Virus as a Case Study.

Early detection of tomato yellow leaf curl virus (TYLCV) in a previously unaffected tomato production district in Australia allowed its spread to be evaluated spatially and temporally. The population dynamics of the TYLCV vector, Bemisia argentifolii (silverleaf whitefly, SLW), were also evaluated. The district is a dry tropical environment with a clear break to commercial production during the summer wet season. The incidence of TYLCV within crops and its prevalence through the district was influenced by weather, location, vector movements, and the use of Ty-1 virus-resistant hybrids. Rainfall had an important influence, with late summer and early autumn rain suppressing the levels of SLW and, by contrast, a dry summer supporting faster population growth. The use of Ty-1 hybrids appears to have reduced the incidence of TYLCV in this district. There was limited use of Ty-1 hybrids during 2013, and by season end, crops had moderate levels of SLW and high virus incidence. The 2015 and early 2016 season had high SLW populations, but TYLCV incidence was lower than in 2013, possibly due to the widespread adoption of the Ty-1 hybrids reducing virus spread. This study provides valuable epidemiology data for future incursions of begomoviruses, and other viruses spread by SLW.