Summer Climatic Conditions Research Articles

Model Projections of East Asian Summer Climate under the ‘Free Arctic’ Scenario

This paper addresses the ‘ice-free Arctic’ issue under the future global warming scenario. Four coupled climate models used in the third phase of the Coupled Model Intercomparison Project (CMIP3) were selected to project summer climate conditions over East Asia once the Arctic becomes ice-free. The models project that an ice-free Arctic summer will begin in the 2060s under the SRESA1B (according to IPCC Special Reports on Emissions Scenarios) simulations. Our results show that the East Asian summer monsoons will tend to be stronger and that the water vapor transport to central northern China will be strengthened, leading to increased summer precipitation in central northern China. The models also project an intensified Antarctic Oscillation, a condition which favors increased precipitation in South China’s Yangtze River Valley. The overall precipitation in Northwest China is projected to increase under ice-free Arctic summer conditions.

Thermal analysis of wood-based test cells

The objective of the present paper is to evaluate the thermal performance of diverse wood-based panels in small-scale test cells of 1 m × 1 m × 1 m of internal volume. The thermal evaluations took place under the climatic conditions of Curitiba, Brazil (latitude 25.5°S, elevation 917 m above sea level), which is characterized by a subtropical climate with high daily and annual amplitudes of the air temperature. The research comprised of the following steps: (1) heat flux measurements through each panel configuration; (2) indoor temperature measurements under summer and winter climatic conditions. Reference material for indoor temperature comparisons was a prototype made with ordinary ceramic bricks, plastered on both sides. Air temperature measurements were carried out with data-loggers, heat flux plates were attached to an exposed north facade of each test cell, while incoming solar radiation was measured with an experimental solarimeter.

Energy efficient fuzzy based combined variable refrigerant volume and variable air volume air conditioning system for buildings

Energy conservative building design has triggered greater interests in developing flexible and sophisticated air conditioning systems capable of achieving enhanced energy-savings potential without sacrificing the desired thermal comfort and indoor air quality (IAQ). This research work greatly aimed at achieving enhanced energy conservation, good thermal comfort and better IAQ for space conditioning with the application of combined variable refrigerant volume (VRV) and variable air volume (VAV) air conditioning (A/C) systems. Experimental investigation on the proposed combined air conditioning system with the application of intelligent fuzzy logic controller was performed for summer and winter climatic conditions to substantiate the energy-savings capability. The proposed system experimentally analyzed under fixed ventilation, demand controlled ventilation (DCV) and combined DCV and economizer cycle (EC) ventilation techniques effectively conserved 44% and 63% of per day average energy-savings in summer and winter design conditions respectively, while compared to the conventional constant air volume (CAV) A/C system. The results of the present investigation have proved that the proposed combined air conditioning system operated under the different ventilation strategies and controlled by the intelligent fuzzy logic controller (FLC) can be considered as an efficient technology to achieve good thermal comfort, IAQ and energy conservation in the modern heating, ventilation and air conditioning (HVAC) applications.

Mineral dust and elemental black carbon records from an Alpine ice core (Colle Gnifetti glacier) over the last millennium

Black carbon (BC) and mineral dust aerosols were analyzed in an ice core from the Colle Gnifetti glacier (Monte Rosa, Swiss‐Italian Alps, 45°55′N, 7°52′E, 4455 m above sea level) using chemical and optical methods. The resulting time series obtained from this summer ice record indicate that BC transport was primarily constrained by regional anthropogenic activities, i.e., biomass and fossil fuel combustion. More precisely, the δ13C composition of BC suggests that wood combustion was the main source of preindustrial atmospheric BC emissions (C3:C4 ratio of burnt biomass of 75:25). Despite relatively high BC emissions prior to 1570, biomass burning activity and especially C4 grassland burning abruptly dropped between 1570 and 1750 (C3:C4 ratio of burnt biomass of 90:10), suggesting that agricultural practices strongly decreased in Europe during this cold period of the “Little Ice Age” (LIA). On the other hand, optical analysis revealed that the main source for atmospheric dust transport to the southern parts of the Alps during summer months was driven by large‐scale atmospheric circulation control on the dust export from the northern Saharan desert. This southern aerosol source was probably associated with global‐scale hydrologic changes, at least partially forced by variability in solar irradiance. In fact, periods of enhanced Saharan dust deposition in the ice core (around 1200–1300, 1430–1520, 1570–1690, 1780–1800, and after 1870) likely reflect drier winters in North Africa, stronger North Atlantic southwesterlies, and increased spring/summer precipitation in west‐central Europe. These results, therefore, suggest that the climatic pejorations and the resulting socioeconomic crises, which occurred in Europe during periods of the LIA, could have been indirectly triggered by large‐scale meridional advection of air masses and wetter summer climatic conditions.

The effect of elevated inlet air temperature and relative humidity on cogeneration system

The effect of elevated inlet air temperature and relative humidity on a gas turbine (GT) cogeneration system performance was investigated. The analysis was carried out on a GT of a capacity 171 MW at ISO condition, which is integrated with a dual pressure heat recovery steam generator (HRSG), the cogeneration system had been tested under Kuwait summer climate conditions. A computational model was developed and solved using engineering equation solver professional package to investigate the performance of a dual pressure GT-HRSG system. The suggested HRSG is capable of producing high-pressure superheated steam at 150 bar and 510°C to operate a power generation steam turbine cycle, and a medium pressure saturated steam at 15 bar to run a thermal vapor compression (TVC) desalination system. In this research, the influence of elevated inlet air temperature and relative humidity on the energy assessment of the suggested cogeneration system was thoroughly investigated. Results indicated that operating GT under elevated values of inlet air temperatures is characterized by low values of net power and thermal efficiency. At elevated inlet air temperatures, increasing relative humidity has a small positive impact on GT cycle net power and thermal efficiency. Integrating the GT with HRSG to generate steam for power generation and process heat tends to increase energy utilization factor of the system at elevated inlet air temperatures. Increasing inlet air temperature plays a negative impact on power to heat ratio (PHR), while relative humidity has no effect on PHR. Copyright © 2009 John Wiley & Sons, Ltd.

Quantification of greenhouse gas emissions from a beef feedlot system in south-east Australia during summer conditions

Feedlot management systems for beef cattle are becoming a more common practice in Australia reflecting opportunities to ensure quality of product whilst maintaining cost efficiencies within production. However, feedlot systems have been identified as point sources of greenhouse gases emissions (GGE: methane, nitrous oxide and the indirect greenhouse gas ammonia). It has been estimated that feedlot systems contribute 3.5% of total direct methane emissions (Alford et al. 2006), and 30% of total emissions from livestock wastes. Furthermore, approximately 1% of total N2O emissions from agriculture are attributed to livestock. This paper reports methane, N2O and NH3 emissions from an Australian feedlot system managed under summer climatic conditions. It compares actual measured emissions with estimated from three recognised models used by national governments to estimate total GGE per annum from livestock agriculture.

Incidence of Hemorrhagic Disease in White-Tailed Deer Is Associated with Winter and Summer Climatic Conditions

Hemorrhagic disease (HD) is an important vector-borne disease of white-tailed deer (Odocoileus virginianus). The objective of this study was to determine whether temperature and precipitation were associated with a measure of annual incidence of HD in white-tailed deer from Virginia. The annual percentages of deer with hoof wall growth interruptions (a clinical sign of HD) from four climate divisions in the HD endemic area of Virginia recorded during 1993-2006 were used as indicators of annual HD incidence. Pearson's correlation coefficients between these indicators of incidence and average temperature (degrees F) or total precipitation (in.) for each month, as well as for winter (January-February), early summer (June-July), and late summer/fall (August-September-October) seasons were calculated. Strong direct correlations between the measure of annual HD incidence and average temperature for winter (r = 0.39, P = 0.003, n = 57), early summer (r = 0.51, P < 0.0001, n = 57), and late summer/fall (r = 0.42, P = 0.001, n = 57) were evident. There also was a strong inverse correlation between the measured annual HD incidence and June precipitation (r = -0.44, P = 0.0006, n = 57). Poisson regression models of seasonal temperatures and June precipitation to annual percentage of deer with hoof wall growth interruptions were developed. Based on Akaike's Information Criterion with small sample size correction (AICc), the global model was selected as the top model. Higher winter and summer temperatures may increase vector capacity and competence, and lower precipitation in June may create favorable breeding sites for midges.

Thermal analysis of wood–cement panels: Heat flux and indoor temperature measurements in test cells

The aim of the present paper is to characterize the physical and mechanical properties and to evaluate the thermal performance of wood–cement panels using wood flour originated from lumber industries rejects. The research comprised of several steps: (1) physical and mechanical analysis; (2) heat flux measurements using small-scale test cells of 1 m 3 of internal volume and (3) indoor temperature measurements under summer and winter climatic conditions in Curitiba, Brazil (latitude 25.5°S, elevation 917 m above sea level). Reference material for indoor temperature comparisons was a prototype made with ordinary ceramic bricks, plastered on both sides. Air temperature measurements were carried out with data loggers, heat flux plates were attached to an exposed north facade of each test cell, while incoming solar radiation was measured with an experimental solarimeter.

Numerical analysis of a coupled solar collector latent heat storage unit using various phase change materials for heating the water

A theoretical model based on the energy equations was developed to predict the thermal behaviour and performance of a solar latent heat storage unit (LHSU) consisting of a series of identical tubes embedded in the phase change material (PCM). During charging mode, a heat transfer fluid (hot water) from the solar collector passes through the tubes and transfers the collecting heat of solar radiation to the PCM. The heat stored in the liquid PCM is next transferred to water during discharging mode to produce heating water. A simulation program based on the finite volume approach was also developed to numerically evaluate the thermal performance of the LHSU. The model was first validated by comparing the results of numerical simulations to the experimental data. A series of numerical simulations were conducted for three kinds of PCM ( n-octadecane, Paraffin wax and Stearic acid) to find the optimum design for a given summer climatic conditions of Marrakech city: solar radiation and ambient temperature. Optimization of the LHSU involves determination of the mass of the PCM, the number of tubes, and the flow rate water in solar collector that maximise the thermal storage efficiency. Several simulations were also made to study the effect of the flow rate water on its outlet temperature, during the discharging mode.

Summer temperature effects on deaths and hospital admissions among the elderly population in two Italian cities

In developed countries the effects of climate on health status are mainly due to temperature. Our analysis is aimed to deepen statistically the relationship between summer climate conditions and daily frequency of health episodes: deaths or hospital admissions. We expect to find a U-shaped relationship between temperature and frequencies of events occurring in summer regarding the elderly population resident in Milano and Brescia. We use as covariates hourly records of temperature recorded at observation sites located in Milano and Brescia. The analysis is performed using Generalized Additive Models (GAM), where the response variable is the daily number of events, which varies as a possibly non-linear function of meteorological variables measured on the same or previous day. We consider separate models for Milano and Brescia and then we compare temperature effects among the two towns and among different age classes. Moreover we consider separate models for all diagnosed events, for those due to respiratory disease and those due to circulatory pathologies. Model selection is a central problem, the basic methods used are the UBRE and GCV criteria but, instead of conditioning all final conclusions on the best model according to the chosen criterion, we investigated the effect of model selection by implementing a bootstrap procedure.

Climate impacts on Mediterranean blue tit survival: an investigation across seasons and spatial scales

AbstractIn some hole nesting passerine species, long‐term monitoring data are available for several geographically independent populations. Climate forcing can then be documented and predictions made on the scale of distribution ranges. Several demographic studies of Paridae report dramatic impacts of wintertime climatic factors. However, these studies were undertaken in populations located in the northern parts of the species' ranges. Studies on the survival of Paridae in their southern ranges are necessary in order to assess potential latitudinal variation in climate forcing on survival. Based on monitoring of individual adult blue tits (Parus caeruleus), the effects of climatic factors on annual survival were assessed in three distinct Mediterranean populations. In these regions, climatic conditions in early summer might be expected to have a strong impact because they can be extremely hot and dry and because at this time of year Paridae are subjected to intrinsic constraints that stem from energetically costly postbreeding moult, recovery from reproductive costs, and from population densities inflated by the new cohort of fledglings. The impact of climatic conditions in early summer was, thus, addressed in addition to that prevailing in winter. In order to consider a large number of local climatic variables while limiting statistical power loss, integrative indices of local climate were built using multivariate techniques. In addition, the NAO and three large‐scale factors that are closely linked with atmospheric and oceanic circulation in the intertropical zone were considered as potentially influential factors in winter and early summer. Relationships between blue tit survival and indices of local temperature and precipitation in winter and in early summer were detected. Adult survival also correlated with a large‐scale tropical index in early summer: rainfall in the Sahel. This is one of the first quantitative indications that fluctuations in summer climatic conditions explain a significant part of the temporal variation in adult survival in unconnected populations of a sedentary European vertebrate. Furthermore, the results support the hypothesis that summertime local climates in Western Europe are closely linked with atmospheric and oceanic circulation in the intertropical zone.

Tunica dartos index as a parameter for measurement of adaptability of rams to subtropical conditions of Egypt

ABSTRACTThe aim of the present study was to investigate the effects of hot summer climatic conditions (compared to winter) on the libido, semen quality traits, level of serum testosterone hormone and some physiological and body measurements of Egyptian Suffolk rams. A parameter for the tolerance of the rams to adverse hot climatic conditions, designated as the tunica dartos index (TDI), was estimated as the multiplication of the percentage change in scrotal length and that of the percentage difference between rectal temperature and scrotal skin temperature. The relationships between the TDI and semen characteristics were also estimated. The results showed that in summer, the reaction time, pH, percentage dead and abnormal spermatozoa, acrosomal damage and temperatures of rectum, body skin and scrotal skin and scrotal length were significantly higher, while sperm motility, sperm concentration, scrotal circumference and testis length were significantly lower than in winter. The correlation coefficient (r) values estimated between the TDI and each of the semen pH, ejaculate volume, sperm motility and sperm cell concentration were positive, and those estimated between the TDI and each of the reaction time, dead and abnormal spermatozoa and acrosomal damage were negative. The best values of libido (low reaction time), semen pH, semen motility percentage, sperm cell concentration and testosterone level were recorded with a high TDI level (7.5 and more), while those of percentage of dead spermatozoa, sperm abnormalities and acrosomal damage were recorded with a low TDI level (less than 4.5). It can be concluded that the TDI correlates well with the reproductive ability of the ram and can be a reliable parameter to indicate the tolerance of rams to hot subtropical conditions in Egypt.

Parametric study of various configurations of hybrid PV/thermal air collector: Experimental validation of theoretical model

In this paper, an attempt has been made to evaluate the overall performance of hybrid PV/thermal (PV/T) air collector. The different configurations of hybrid air collectors which are considered as unglazed and glazed PV/T air heaters, with and without tedlar. Analytical expressions for the temperatures of solar cells, back surface of the module, outlet air and the rate of extraction of useful thermal energy from hybrid PV/T air collectors have been derived. Further an analytical expression similar to Hottel–Whiller–Bliss (HWB) equation for flat plate collector has also been derived in terms of design and climatic parameters. Numerical computations have been carried out for composite climate of New Delhi and the results for different configurations have been compared. The thermal model for unglazed PV/T air heating system has also been validated experimentally for summer climatic conditions. It is observed that glazed hybrid PV/T without tedlar gives the best performance.

Studies on the Drying Characteristics of Zingiber Officinale Under Open Sun and Solar Biomass (Hybrid) Drying

Drying characteristics of Zingiber officinale (Ginger) under the open sun and direct type natural convection solar biomass (hybrid) drying were studied. It has been observed that under open sun drying conditions, the drying rate depends on the product thickness and climatic conditions. The results have been drawn for both the summer (April-May, 2004) and winter (November-January, 2003–04) months of Delhi, in India. In the hybrid drier, the ginger, with a thickness of 0.008 m, dried in 33 hours in comparison to 96 hours in open-sun drying. The overall drying efficiency of the hybrid drier was found to be 18% and 13% under summer and winter climatic conditions respectively. The loss of volatile oil content of the ginger is less in hybrid drier in comparison to open sun drying. It was found that the average drying air temperature of 60°C with average air velocity of 0.6m/sec was sufficient for the drying of ginger in the hybrid drier. Ginger quality after drying is better and drying time is less in the hybrid drier in comparison to open-sun drying. The hybrid drier is a simple device, which can be manufactured with locally available materials and can be used for drying of other spices, vegetables and fruits etc.

Optimum Harvesting Time of Four Mentha Species in Northern Finland

The effect of harvesting time on the quality and quantity of mint oils produced from plants grown in short summer and long-day climatic conditions of northern Finland (64°40′N and 25°E) was examined to determine what growth stage is best for cutting to obtain the highest possible biomass (herb yield), oil content and suitable oil composition. In the field experiment, plants cut only once at the end of August were compared with those of two cuttings. The first cut was at the beginning of August and the second cut in the middle of September. The mint species were Mentha piperita L. “peppermint”, M. canadensis “cornmint”, M. canadensis “Sakhalin mint” and M. spicata L. “spearmint.”

Seasonal precipitation in the south-central Helan Mountain region, China, reconstructed from tree-ring width for the past 224 years

Chinese pine (Pinus tabulaeformis Carr.) trees from the Helan Mountain range in central China have been used to reconstruct total January–July precipitation from AD 1775 to 1998. For the calibration period R2adj = 0.52. Narrow rings are associated with below-average precipitation from March through August. Wide rings are produced in years when the East Asian summer monsoon front arrives early. We use local historical writings over the last 300 years about extreme climatic conditions between spring and early summer to verify the extreme years. Most of the extreme dry years could be identified in local historical documents. Another East Asian summer monsoon front related precipitation reconstruction from northern Helan Mountain is also used to verify this reconstruction. They are well correlated from year to year, with a correlation coefficient of 0.52 (N = 218), and the wet or dry extreme events are well matched in many cases. This comparison could indicate a spatial and temporal connection of spring to early summer climatic conditions for the southern to northern portion of the Helan Mountain region. The sustained wet period before the 20th century lasts from the 1850s to the 1890s, and the longest dry period before the 20th century is in the 1830s and 1840s, largely coinciding with a spring–summer drought in Kashmir. Overall, multiyear fluctuations, such as the spectacular large-scale drought of the late 1920s and droughts in the 1830s–1840s and the 1970s, are well captured in this reconstruction, but only the 1970s drought is in the instrumental period. The reconstruction shows increasing variance from the 18th to the late 20th century.

Simulation of Greenhouse Management in the Subtropics, Part I: Model Validation and Scenario Study for the Winter Season

Adaptation of greenhouse climate management strategy to local climatic conditions is very important for the improvement of resource use efficiency of greenhouse crop production. The objective of this study was to explore alternatives to the existing Venlo-type greenhouse climate control policy under Chinese subtropical climate conditions, through simulation analysis using the Greenhouse Process (KASPRO) model. Experiments were carried out in a Dutch Venlo-type glasshouse on a farm in Shanghai (31·3 °N, 121·4 °E), to collect climate and crop data to validate the model. The results show that using outside hourly weather data as inputs, the KASPRO model generally gives satisfactory predictions of greenhouse air temperature and humidity, and of canopy transpiration rate under both summer and winter climate conditions for subtropical China. After the model validation, scenario studies were carried out to investigate the possible responses of crop biomass production and energy consumption to different nighttime and daytime air temperature set points and canopy size based on leaf area index (LAI), under the winter climate conditions typical of subtropical China. The scenario analysis shows that, during winter, the highest biomass production is achieved when the daily mean air temperature in the greenhouse is 19·7 °C, which is realised when day and night air temperature set points are 23 and 18 °C, respectively. The highest energy use efficiency for biomass production is achieved when daily mean air temperature in the greenhouse is 18 °C, which is realised by setting the set points of air temperature at 19 and 15 °C, respectively. During winter, crop biomass production reaches the maximum at a LAI of 3. The energy consumption increases with the canopy LAI. It is concluded that both from the biomass production and energy saving point of view, an air temperature set point of 19 °C for daytime and 15 °C for nighttime and a canopy LAI of 2–3 provides the most energy-efficient conditions for greenhouse cucumber crop production under the winter climate conditions in subtropical China.

An virtual numerical experiment to understand the impacts of recovering natural vegetation on the summer climate and environmental conditions in East Asia

By applying a regional integrated environmental model system (RIEMS), a virtual numerical experiment is implemented to study the impacts of recovering natural vegetation on the regional climate and environmental conditions. The results show that recovering the natural vegetation in large scale could have significant influence on summer climate in East Asia. Not only would it be able to change the surface climate, but also to modify to certain extent the intensity of monsoon circulation. Although this is a virtual experiment at an extremely ideal condition, the implication of the simulating results is that the on-going nation-wide activities to recover the crop land for forest and pasture must be managed according to the local natural climate, hydrological and soil conditions. Only under such a condition, would the recovering of natural vegetation bring about significant climate and environmental benefits at regional scale.

Réintroduction de sphaignes dans une tourbière exploitée : Évaluation de divers moyens de protection contre la dessiccation

In order to restore peatlands after peat harvesting operations, Sphagnum diaspores were reintroduced in combination with i) physical protection devices or ii) an irrigating system. The response of five Sphagnum species (Sphagnum angustifolium [C. Jens. ex Russ.] C. Jens. in Tolf, S. magellanicum Brid., S. papillosum Lindb., S. fuscum [Schimp.] Klinggr. and S. capillifolium [Ehrh.] Hedw.) was investigated in relation to two types of peat substrates for two growing seasons. The physical protections consisting of plastic shade cloth (40% and 60% shade) improved the development of a greater number of capitula compared with control surfaces without protection or surfaces covered with a perforated polyethylene sheet. This stimulating effect could be caused by higher humidity created by a shade screen. Irrigation also enhanced the establishment success of Sphagnum but the effect was less successful than expected. During a year with normal summer climatic conditions (1993), the sphagna of the sections Cuspidata and Acutifolia established well with equal number of capitulum after 117 days of growth. In contrast, after a second year of growth which was much more humid because of abundant rainfalls, the sphagna of section Cuspidata were maintained or multiplied while those of section Acutifolia regressed. Since it is difficult to predict long-term climatic conditions, we suggest the reintroduction of a mixture of many species in order to favor the adaptation of the moss cover to diverse climatic conditions. In conclusion, we recommend the reintroduction of a variety of Sphagnum species under physical protections like plastic shade screen to favor an adequate microclimate during the restoration phase of a continuous moss carpet.

A Community of Snow Algae on a Himalayan Glacier: Change of Algal Biomass and Community Structure with Altitude

A community of snow algae on a Himalayan glacier, the Yala Glacier (5100-5700 m a.s.l.), Langtang region of Nepal Himalaya, were quantitatively analyzed. This is the first report on snow algae from the Himalayan region. In this glacier, 11 species of snow algae were observed: Chloromonas sp., Trochiscia sp., Mesotaenium berggrenii, Cylindrocystis brébissonii, Koliella sp., Ancylonema nol-denskioeldii, Raphidonema sp., three Oscillatoriacean algae, and one unknown coccoid alga.The algal biomass estimated by the total cell volume rapidly decreased as the altitude increased. In particular, the rate of decrease of algal biomass was larger in the upper snow environment than in the lower ice environment. The structure of algal community represented by the proportion of each species to the total algal biomass also differed by altitude. From the difference of the algal community, we divided the glacier into three zones: the Lower Zone (5100-5200 m a.s.l.; stable ice-environment), with 7 species dominated by Cylindrocystis brébissonii; the Middle Zone (5200-5300 m a.s.l.; unstable transition area between ice-environment and snow-environment), with 11 species dominated by Mesotaenium berggrenii; and the Upper Zone (5300-5430 m a.s.l.; stable snow-environment), with 4 species dominated by Trochiscia sp. This vertical zonation of the algal community type and biomass may reflect the difference in summer climatic conditions with altitude. Species number and Simpson's diversity index was highest in the Middle Zone where environmental conditions frequently changed. Our results seems to agree with the intermediate disturbance hypothesis.Since the snow algae in the accumulation area (>5250 m a.s.l.) of the glacier is annually stored in glacial strata, the algal biomass and community structure recorded in glacier ice-cores can be a new information source for the studies on past climate change in this region.