Air Temperature Research Papers - Academia.edu (original) (raw)

During the last glacial-interglacial cycle, northern hemispheric (NH) ice-sheets experienced dramatic changes in radiative forcing, due to orbitally-driven insolation changes and varying greenhouse gas concentrations. This direct forcing caused temperature changes and eventually ablation anomalies. Orbital-scale variations in the atmospheric circulation caused anomalies in temperature advection and precipitation/snowfall that also strongly contributed to the mass balance and hence the time-evolution

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- Climate Change, Global change, Communication model, Younger Dryas

Hydrometeors spectra evolution induced by coalescence processes is simulated using a microphysical model of the Berry and Reinhard (1974) type including hydrometeors of seven kinds: water drops, plate-like and columnar crystals, dendrites, snowflakes, graupel and hail. The sensitivity of spectra evolution to several parameters, such as air temperature, drop freezing rate, initial liquid water and ice particles content is studied. The Berry and Reinhard (1974) method was used for numerical integration of corresponding stochastic coalescence equations. A remarkable impact of ice processes on the evolution of hydrometeors of all types is demonstrated. The amount of large droplets in mixed phase experiments is significantly less than that in the experiment without the ice phase. The main factor causing the cessation of water spectrum broadening is connected with a crucial decrease of the coalescence rate between water droplets due to permanent elimination of the largest droplets from the drop spectrum as a result of ice-water interaction and drop freezing. The results of simulations show that when only coalescence processes are considered, relative amounts of snowflakes and graupel crucially depend on air temperature. Under comparably high temperatures it is snowflakes that are the dominating hydrometeor type, while under low temperatures graupel can be the dominating hydrometeor type due to an increased rate of drop freezing. A high sensitivity of snowflake/graupel content ratio to the initial size of crystals is demonstrated. Initial liquid water content in model experiments appears to be one of the most important factors determining the formation not only of graupel, but of snowflakes as well. Results indicate the existence of a "critical" minimum concentration of water drops and minimum broadness of the drop size spectrum, which means that when the corresponding values are smaller there is no large snowflake or graupel generation.

Weather variation and climate fluctuations are the main sources of ecosystem variability in remote mountain lakes. Here we describe the main patterns of seasonal variability in the ecosystems of nine lakes in Europe, and discuss the implications for recording climatic features in their sediments. Despite the diversity in latitude and size, the lakes showed a number of common features. They were ice-covered between 5-9 months, and all but one were dimictic. This particular lake was long and shallow, and wind action episodically mixed the water column throughout the ice-free period. All lakes showed characteristic oxygen depletion during the ice-covered-period, which was greater in the most productive lakes. Two types of lakes were distinguished according to the number of production peaks during the ice-free season. Lakes with longer summer stratification tended to have two productive periods: This is the third of 11 papers published in this special issue on the palaeolimnology of remote mountain lakes in Europe resulting from the MOLAR project funded by the European Union. The guest editor was Richard W. Battarbee.

- by Jordi Catalan and +5
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- Geology, Life Sciences, Paleolimnology, Stratification

El método FAO Penman (PM), es el más confiable para estimar la evapotranspiración de referencia (ETo) y es recomendado por la FAO como estándar para verificar otros métodos empíricos. En su utilización es necesaria información de cuatro parámetros meteorológicos: temperatura del aire, humedad relativa, velocidad del viento y radiación neta. La poca disponibilidad de estos parámetros limita el uso del método en muchos lugares; por lo que los modelos Thornthwaite (TM) y Hargreaves (HM) son usados con frecuencia, ya que únicamente se basan en medidas de temperatura del aire, medidas comunes en muchas estaciones meteorológicas en todo el mundo, por lo que son una opción para estimar la ETo. Sin embargo, con el objetivo de obtener resultados apropiados de ETo, los modelos HM y TM deben ser calibrados de acuerdo con las condiciones locales. En el presente estudio, los coeficientes originales de TM y HM son modificados para una calibración local en climas semi-áridos y tropicales sub-húmedos del estado de Yucatán, México, usando como estándar la ecuación Penman-de FAO. Se usaron datos meteorológicos de dos estaciones en el estado de Yucatán, México que corresponden a un clima costero semi-árido (Progreso) y a un clima tropical sub-húmedo tierra adentro (Mérida). En la comparación se analizaron los índices de concordancia (D), confianza (C), correlación (R) y regresión (R 2 ), así como indicadores del sesgo medio del error (MBE), raíz cuadrada media del error (RMSE), error relativo (RE) y el cociente entre ambas estimaciones promedio de ETo ( r). Usando HM sin ajuste se obtuvieron buenas estimaciones de ETo en Mérida y Progreso, con valores de C de 0.825 y 0.816, respectivamente. No se recomienda el uso de TM sin ajuste en ninguna de las estaciones meteorológicas estudiadas. Sin embargo, en ambas estaciones, el modelo TM estima mejor la Eto durante los meses lluviosos (de junio a octubre). En ambas estaciones meteorológicas, costera y de tierra adentro, se obtuvieron mejores estimaciones anuales de ETo con el uso de HM sin ajuste (valores de C de 0.906 y 0.917, respectivamente).

The adequacy of radial basis function neural networks to model the inside air temperature of a hydroponic greenhouse as a function of the outside air temperature and solar radiation, and the inside relative humidity, is addressed. As the model is intended to be incorporated in an environmental control strategy both o -line and on-line methods could be of use to accomplish this task. In this paper known hybrid o -line training methods and on-line learning algorithms are analyzed. An o -line method and its application to on-line learning is proposed. It exploits the linear-non-linear structure found in radial basis function neural networks.

- by Antonio E B Ruano
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- Engineering, Neural Networks, Environmental Control, Radial Basis Functions

A simple climate model has been developed to investigate the existence of the small ice cap instability in the Southern Hemisphere. The model consists of four coupled components: an atmospheric energy balance model, a thermodynamic snow-sea ice model, an oceanic mixed layer model and a terrestrial ice model. Results from a series of experiments involving different degrees of coupling in the model show that the instability appears only in those cases when an explicit representation of the Antarctic ice sheet is not included in the model. In order to determine which physical processes in the ice sheet model lead to a stabilization of the system we have conducted several sensitivity experiments in each of which a given ice sheet process has been removed from the control formulation of the model. Results from these experiments suggest that the feedback between the elevation of the ice sheet and the snow accumulation-ice ablation balance is responsible for the disappearance of the small ice cap instability in our simulation. In the model, the mass balance of the ice sheet depends on the air temperature at sea level corrected for altitude and it is, therefore, a function of surface elevation. This altitudemass balance feedback effectively decouples the location of the ice edge from any specific sea level isotherm, thus decreasing the model sensitivity to the albedotemperature feedback, which is responsible for the appearance of the instability. It is also shown that M. A. Morales Maqueda ()) A

- by Miguel Angel Morales Maqueda
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- Oceanography, Thermodynamics, Sea Level, Sea Ice

Artificial canopy gaps were made by felling trees in rain forest on Maraca Island. There were three replicates of each gaṕ

- by virgilio viana
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- Forest Ecology And Management, Soil Chemistry, Forest Ecology, Biological Sciences

This study reports the seasonal assessment of energy balance components and carbon dioxides fluxes over a drip irrigated kiwifruit orchard, with a Leaf Area Index (LAI) of 3 at full canopy development. The most remarkable amount of energy partitioning throughout the whole season was due to latent heat flux that had values approximating to those of sensible heat flux (about

- by T. Georgiadis
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- Carbon Dioxide, Seasonality, Water use efficiency, Eddy Covariance

In this analysis, we considered three building types that offer the most savings potential: residences, offices, and retail stores. Each building type was characterized in detail by Pre-1980 (old) or 1980 + (new) construction vintage and... more

Fish sauce is a popular Asian food ingredient having specific flavor that gives pleasure to the senses of taste. However, fish sauce contains high-salt content, which is nowadays not desirable by health-conscious consumers. Recently, it has been shown that electrodialysis succeeds in reducing the salt content of fish sauce without affecting its important characteristics over a specific range of residual salt content. In this study the effect of electrodialysis pretreatment prior to spray drying to produce low-salt fish sauce powder, which is a more shelf-stable and convenient product compared with liquid fish sauce, was investigated. Product recovery, morphology and selected physicochemical properties, i.e., moisture content, water activity, hygroscopicity, as well as X-ray diffraction (XRD) patterns of the fish sauce powder were determined. The ED-treated-fish sauces of various salt contents (in the range of approximately 2-25% w/ w) were spray dried at inlet drying air temperatures of 120-180°C. It was found that the feed salt concentration and inlet air temperature had significant effects on all observed variables. This is due to the fact that the feed salt concentration strongly affected water removal from the ED-treated-fish sauce during spray drying, leading to significant alterations of the ED-treated-fish sauce powder properties.

- by Nathamol Chindapan
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- Food Engineering, Morphology, Concentration, Water Activity
- by Haralambos Feidas
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- Time Series, North Atlantic Oscillation, Seasonality, Atmospheric sciences

Biogenic sulfur gases emitted from Chinese rice paddies were measured with a laboratory incubation and a closed chamber method in the field. Six speciations of sulfur-containing gases were detected in both conditions: hydrogen Ž . Ž . Ž . Ž . Ž sulfide H S , carbonyl sulfide COS , methyl mercaptan CH SH , carbon disulfide CS , dimethyl sulfide CH SCH 2 3 2 3 3 . Ž . or DMS and dimethyl disulfide CH SSCH or DMDS . Among them, DMS comprised the major part of the sulfur 3 3

- by li w
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- Multidisciplinary, Seasonal variation, Air Temperature, Hydrogen Sulfide

We give an overview of the history of the ice cover studies in Lake Baikal and a detailed description of the temporal and spatial variability of Lake Baikal ice conditions based on satellite and historical data. We analyze the long-term evolution of ice conditions using historical data and recent observations from satellite altimetry and radiometry for 1992-2004 for northern, middle, and southern Baikal. These data show a recent (since the 1990s) tendency for colder winters, with earlier ice formation, later ice break-up, and ice duration increase. These observations are in agreement with the long-period cycles of air temperature variability (warming between the 1970s and 1990s, with a cooling phase afterwards). We then compare air temperature data from meteorological stations to ERA-40 reanalysis and suggest that ERA-40 data can be used to assess seasonal and interannual changes of air temperature for Lake Baikal. The ERA-40 data also indicate a recent tendency for colder winters and for warmer summers. We further analyze how the ice regime is influenced by air temperature and how this influence is affected by dynamic (wind field, currents) and other (bathymetry, precipitation, etc.) factors. We estimate the relationship between air temperature parameters and the timing of ice events (ice formation and fast ice duration) and show that air temperature has the strongest effect on the ice regime. Dynamic and other factors interfere with the thermal influence, resulting in a change of ice formation dates and ice duration compared to the relationship that takes into account only the influence of air temperature.

- by Alexei Kouraev
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- Earth Sciences, Limnology, Lake Baikal, Biological Sciences

A numerical model was developed for the computation of the wind field, air temperature and humidity in the urban canopy layer and in the atmospheric boundary layer above urban areas. The model is of k–ε type. The ensemble-spatial averaged three-dimensional Reynolds equations, equation of continuity, turbulent kinetic energy equation (k-equation), and equation for dissipation rate of turbulent energy (ε-equation) are solved together with equations of heat and moisture transfer in the air. Inside the urban canopy layer, volumes of buildings and other urban structures are accounted for by a spatial averaging procedure. With given average building height and building width for each grid mesh, effects of buildings on the momentum transfer are modelled by introducing a form drag force. Temperatures of the ground surface, building walls or roof are computed by the solution of the heat conduction equation in the ground or walls, roof. Evaporation at the ground surface is evaluated using a Bowen ratio. The exhausted heat by building air conditioning is evaluated by employing a building air conditioning model. This heat together with traffic-induced artificial heat are accounted for in the model as heat sources. A numerical model for the momentum, heat and moisture transfer in the plant canopy is also coupled to the model to investigate the effects of vegetation on the urban climate. Verification of the model against observational data in the Tokyo Metropolitan area, Japan, reveals that the model is capable of simulating the momentum, heat and mass transfer in the urban boundary layer. Especially, the model can compute air temperature, humidity and wind velocity at the street level, which cannot be computed by a general above city atmospheric circulation model.

- by Ca Vu Thanh
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- Mechanical Engineering, Civil Engineering, Heat and Mass Transfer, Urban Climate

Moisture is one of the most deteriorating factors of buildings. The deteriorating effect of moisture occurs mainly during the drying phase, and not in the wetting phase. Appropriate parameters of the drying kinetics are required for the building materials. Environmental factors, such as air temperature, air humidity, and air velocity affect drying. An experimental air dryer of controlled drying air conditions was used to investigate the drying performance of 4 stone materials, 2 bricks and 7 plasters. Drying kinetics was examined at 4 air temperatures, 6 air humidities, and 3 air velocities. A first-order kinetics model was obtained, in which the drying time constant was a function of the drying conditions, and the equilibrium material moisture content was described by the Oswin equation. The parameters of the proposed model were found to be affected strongly by the material and the drying air conditions. The results obtained are very useful in selecting the appropriate plaster to protect existing historic buildings.

- by Maria Karoglou
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- Chemical Engineering, Drying Technology, Air Conditioning, First-Order Logic

During ONR's Shoaling Waves Experiment (SHOWEX) off the coast of North Carolina in November and December 1999, measurements of wind speed and direction as well as air and water temperatures were made using a variety of techniques. This... more

- by Vladimir Irisov
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- Oceanography, North Carolina, Wind, Seawater

Mulching is a technique widely used to conserve soil and moderate its microclimate. Modelling transfer processes in mulches is limited by our lack of understanding of turbulent exchange within the mulch. This paper, the first of a two-part series, reports on measurements of wind and turbulence made above and within a 10 t ha −1 barley-straw mulch using custom-made hot-wires and a tri-axial hot-film probe. Wind regimes within the mulch during daytime (relatively high wind) and nighttime (low wind) differ greatly. During daytime, 10 min average horizontal wind speeds at all levels in the mulch (where they vary nearly exponentially with height) correlate well with (near-logarithmic profile) wind speeds above the mulch and are not affected by the strong temperature inversion existing in the mulch. During nighttime, 10 min average horizontal wind speeds within the mulch are decoupled from (poorly correlated with) wind speeds in the generally stable air above the mulch. Unstable conditions in the mulch at night lead to free convection, which explains the good correlation of 10 min average wind speeds at all heights within the mulch and the high evaporation rates we measured below the mulch. Under high wind conditions most of the drag occurs very near the top of the mulch which behaves as an aerodynamically smooth surface similar to a bare soil. Turbulence within the mulch is of high intensity and is dominated by intermittant gusts, with the extreme values described by a Gumbel distribution. The frequency of the gusts agrees reasonably well with that found for laboratory mixing layers. The wind and turbulence regimes in the mulch resemble in many ways those in plant canopies much larger in height and lower in leaf area density.

- by Michael Novak
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- Earth Sciences, Biological Sciences, Energy Balance, Heat Flux

by high water drainage and nitrates leaching. The first soil group caused a mean of 517 mm of runoff in annual basis, 200 mm higher than this arising from coarse soils. Moreover, 3 tonnes of sediments per hectare, 24.6 kgN/ha and 0.54 kgP/ha were lost annually to surface water from fine soils while the average respective losses originating from coarse soils were only 1.3 tn of sediments/ha, 13.6kgN/ha and 0.17kgP/ha. The sensitivity ranking of the soil types to TN and TP losses was silty-clay-loam>silty-loam>clay>loamy>sandy-loam>sandy. An average of 277 mm of water was percolated annually under the bottom of the soil profile in coarse soils causing the additional leaching of 5.6 kgN-NO 3 /ha whereas the losses originating from fine-textured soils were 153 mm and 2.5 kg/ha respectively. According to their sensitivity in nitrates leaching, the six soil types were ranked in the following order: sandy>loamy>sandy-loam>silty-loam>silty-clay-loam>clay. Conclusions and Perspectives. The results showed that even though under cold climate conditions, with monthly periods of average air-temperatures below zero, the overall amounts of annual TN and TP losses to surface waters as well as nitrates leaching to groundwater were considerable. This demonstrates that the cold climate conditions did not affect the long-term behavior of the six widespread Norwegian soils, which on an annual basis responded similarly to the respective European soils. According to the model's estimations, infiltration with N and P transport still occur in wintertime, and comparing to other studies that reported similar results, different possible explanations were considered. The results demonstrate the need of considering the soil differentiation in Scandinavian countries similarly to the rest of Europe in order to apply mitigation measures against nitrogen and phosphorus losses to surface and groundwater. Please cite this paper as: Panagopoulos I, Mimikou M, Kapetanaki M (2007): Estimation of Nitrogen and Phosphorus Losses to Surface Water and Groundwater Through the Implementation of the SWAT Model for Norwegian Soils. J Soils Sediments 7 (4) 223-231

- by Maria Mimikou
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- Earth Sciences, Phosphorus, Environmental Sciences, Surface Water

This paper presents some of the findings of the European project, RUROS, concentrating on the effect of microclimatic conditions on the use of open spaces in an urban Mediterranean environment. The findings confirm that there is a strong relationship between microclimatic conditions and use of open spaces. Regarding the users of open spaces, a sensitivity to the summer heat was apparent for the age category >65. The spatial distribution of the interviewees demonstrates that in summer, visitors prefer to sit in shaded areas, whereas in autumn and winter sunlit areas are more popular. Observations of the use of space revealed that air temperature and solar radiation were found to be the most dominant parameters in relation to the use of space, with wind speed and relative humidity having a weak effect. In general, people prefer shaded areas at higher air temperatures. However, as high air temperature is a factor contributing to discomfort, overall presence is reduced when air temperature rises significantly. The preference of sun, differs from season to season, depending on the activities taking place in the areas (either designated or not). The diurnal pattern of the use of space also reveals a strong dependency on meteorological parameters. Regarding the time of maximum attendance, this is found in the evening during summer, while there is a transition of the time of maximum attendance towards noon as the season progresses from summer to winter. Daytime attendance figures of autumn and winter are 300-400% higher than in the summer. The need open spaces cover and the social ties provided may also be traced by analyzing the social composition of the interviewees and the reasons bringing them in the space.

- by Marialena Nikolopoulou
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- Statistics, Architecture, Meteorology, Seasonality

In this paper airborne pollen concentration is compared to meteorological data of Trento and S. Michele all'Adige, two sites in the Adige Valley, in Trentino (North Italy). Pollen of Corylus, Alnus, Betula and Ostrya, four winter-spring flowering plants are considered. Pollen sampling was carried out in 1996 by volumetric Hirst-type samplers. For all pollen types considered, maximum pollen concentration coincided in both stations and there was a good overlap of the main pollen season length; the pollen curves of S. Michele a/A and Trento showed a highly positive correlation. The daily airborne pollen concentrations, defined as the number of pollen grains per cubic meter of air (p/m3), were compared to daily meteorological data: minimum and maximum air temperature (~ average relative humidity (%), precipitation (ram), global incident radiation (cal/cm2), average wind direction (~ and wind speed (m/s). A highly positive correlation was found for Corylus and maximum temperature in both monitoring stations. Betula was positively, whereas Ostrya was negatively correlated to relative humidity. With this first analytical approach sharp differences in the atmospheric pollen presence between the stations located at Trento and S. Michele all'Adige were not found. 9 1997 Elsevier Science Ireland Ltd.

- by Elena Gottardini and +1
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- Biological Sciences, Seasonality, Environmental Sciences, Regression Analysis

A statistical downscaling method (SDSM) was evaluated by simultaneously downscaling air temperature, evaporation, and precipitation in Haihe River basin, China. The data used for evaluation were large-scale atmospheric data encompassing daily NCEP/NCAR reanalysis data and the daily mean climate model results for scenarios A2 and B2 of the HadCM3 model. Selected as climate variables for downscaling were measured daily mean air temperature, pan evaporation, and precipitation data from 11 weather stations in the Haihe River basin. The results obtained from SDSM showed that: (1) the pattern of change in and numerical values of the climate variables can be reasonably simulated, with the coefficients of determination between observed and downscaled mean temperature, pan evaporation, and precipitation being 99%, 93%, and 73%, respectively; (2) systematic errors existed in simulating extreme events, but the results were acceptable for practical applications; and (3) the mean air temperature would increase by about 0.7°C during 2011~2040; the total annual precipitation would decrease by about 7% in A2 scenario but increase by about 4% in B2 scenario; and there were no apparent changes in pan evaporation. It was concluded that in the next 30 years, climate would be warmer and drier, extreme events could be more intense, and autumn might be the most distinct season among all the changes.

- by Chong-Yu Xu
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- Climate variability, Seasonality, Atmospheric sciences, Model Selection

Climate change is known to have number effects on plants and animals. Sever- al studies have indicated advances in laying dates of birds in the last ca. 40 years, which could be attributed to air temperatures. The research was conducted in the village of Mokrice, a part of the Hrvatsko Zagorje region (northwestern Croatia). We studied the long-term variation in

- by Jelena Kralj and +1
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- Climate Change, Polish, Air Temperature, Timing of Breeding

At harvest time, maize (Zea mays L.) has a moisture content too high to be stored, and has to be dried. To control the drying impact on maize characteristics, it is necessary to accurately know the spatial distribution of temperature and moisture content in the kernel, and the kinetics of quality loss in relation to these two factors. To this end, a physical model of heat and mass transfer in a maize kernel was designed. The Fick and Fourier equations were solved by the finite element method (FEM). The real 3D geometry of maize was obtained by NMR imaging and then used to build the mesh needed for the FEM computations. The model correctly describes the evolutions of maize moisture and salt-soluble protein content during fluidized-bed drying with a constant drying air temperature between 50°C and 100°C.

- by Luce Elst
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- Mass Transfer, Food Engineering, Kinetics, Heat Transfer

The snow/ice albedo was studied during a 4 week field experiment over first-year sea ice in the Gulf of Bothnia, Baltic Sea, in spring 2004. Observations were made on radiative fluxes, cloud cover, wind, air temperature and humidity, as well as snow/ice temperature, thickness, density and grain size. The albedo variation during the observation period was large: the daily mean albedo ranged from 0.79 over a new snow cover to 0.30 over bare, melting ice. The evolution of the albedo was related to the surface properties, but existing parameterizations based on Arctic data did not explain the observations well. The snow thickness was found to be the most critical factor affecting the albedo. A new parameterization was derived for the albedo dependence on snow thickness, to be applied over the Baltic Sea in spring, when periods of melting and freezing alternate but the ice is still relatively thick (about 0.6 m). The diurnal cycle of solar radiation was large, and the snow/ice metamorphism due to the melting during daylight and refreezing during the night caused a diurnal albedo cycle with a maximum in the early morning and a minimum in the afternoon, with an albedo difference up to 0.14 between the two.

- by Timo Vihma and +1
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- Geophysics, Sea Ice, Atmospheric sciences, Field Experiment
- by Robert Naiman
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- Biological Sciences, Environmental Sciences, Ecological, Relative Humidity

... Michael E. Loik a , ¶ , Travis E. Huxman c , b , Erik P. Hamerlynck d , b and Stanley D. Smith b. ... 19. ME Loik, CD St. Onge and J. Rodgers, Post-fire recruitment of Yucca brevifolia and Yucca schidigera in Joshua Tree National... more

- by Michael Loik
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- Earth Sciences, Climate Change, Arid environments, Biological Sciences

In this work an experimental study is carried out to determine the thermo-hydraulic performance of an intercooler (IC) with flat tubes provided with triangular plain internal fins and louvered external fins when it is used on a car equipped with a low pressure EGR. The main unknowns to be answered are the thermo-hydraulic characteristics of the IC working under humid conditions induced by EGR, the conditions under which the water content in the mixture of air and exhaust gases begins to condense and the conditions under which the condensed water will be retained inside the IC. The exhaust gases are here replaced by a mixture of dry air and water vapour which are mixed upstream of the IC. The IC is submitted at the following testing conditions: on the ambient air side, the air temperature is fixed at around 20°C and the air velocity is settled at 1, 2 and 4ms−1; on the exhaust gases side, the supply temperature was varied between 90 and 150°C, with dry gas flow rates of 20, 50 and 100gs−1, and water contents varying between almost 0 and 0.09kgwkgg−1. At these conditions the IC transfers between 1 and 13kW with overall heat transfer conductance varying between 0.05 and 0.38kWK−1 and effectivenesses between 0.3 and 0.97. A water accumulation inside the IC was detected for the tests carried out at low dry gas flow rate of 20gs−1 and for all the water content explored here (higher than 0.02kgwkgg−1).

- by Cristian Cuevas and +1
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- Mechanical Engineering, Materials Science, Heat Transfer, Heat Exchanger

Power trends for data center facilities continue to grow at an alarming rate. In response to this, data center operators are now implementing various practices such as adding blanking plates, hot aisle/cold aisle containment, etc. Also, in response to ASHRAE's expanded thermal guidelines [1], many data center operators are now raising the supply air temperature in an effort to further conserve energy. However, airflow in a high-density thermal environment is a complex phenomenon and requires an appropriate engineering analysis to understand all of the factors. Improperly implementing such practices, which are now known as "Industry Standard Practices", may result in overheating of IT equipment and thus negatively affect data center operations. In the following scenarios, Cooling Path Management (CPM) is used to understand the airflow / thermal environment of the facility. ASHRAE thermal guidelines are then followed to increase the average temperature of the room. In later scenarios it is shown that with proper airflow management, ASHRAE recommendations can be implemented using a full engineering analysis. Results from the final scenario show that the CRAH unit set point can be increased by 23.8ºF from the baseline scenario and 5.5 kW of stranded capacity can be regained. Results also show that "Industry Standard Practices" only enable the CRAH unit set point to be increased by 13.4ºF. Following the CPM method and ASHRAE thermal guidelines will enable operators to make tangible changes to their data center using objective data.

- by PHILIP VOZZA
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- Negative Affect, Thermal Environment, Data Center, Air Temperature
- by U. Shivhare
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- Chemical Engineering, Drying Technology, Peroxidase, Activation Energy
- by Michael Dettinger and +1
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- Climate Change, Hydrology, Science, Multidisciplinary

Field observations were carried out to determine the influence of a park on the urban summer climate in the nearby areas. The possibilities of reduction in air conditioning energy were investigated. Air temperature, relative humidity and other meteorological factors were measured at many locations inside a park and in the surrounding areas in the Tama New Town, a city in the west of the Tokyo Metropolitan Area, Japan. The observations indicated that vegetation could significantly alter the climate in the town. At noon, the highest temperature of the ground surface of the grass field in the park was 40.3 °C, which was 19 °C lower than that of the asphalt surface or 15 °C lower than that of the concrete surface in the parking or commercial areas. At the same time, air temperature measured at 1.2 m above the ground at the grass field inside the park was more than 2 °C lower than that measured at the same height in the surrounding commercial and parking areas. Soon after sunset, the temperature of the ground surface at the grass field in the park became lower than that of the air, and the park became a cool island whereas paved asphalt or concrete surfaces in the town remained hotter than the overlying air even late at night. With a size of about 0.6 km2, at noon, the park can reduce by up to 1.5 °C the air temperature in a busy commercial area 1 km downwind. This can lead to a significant decrease of in air conditioning energy in the commercial area.

- by Ca Vu Thanh
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- Engineering, Energy Efficiency Buildings, Thermal Environment, Air Conditioning

Heat islands are formed as a result of construction that replaces vegetation with absorptive surfaces. Air temperature rises as a result of formation of heat islands. One suggested method to reduce the emitted heat from asphalt pavement surfaces is to reduce the temperature of the surface by flowing a suitable fluid through the pavement. The heated fluid could then be used for different end applications. Laboratory experiments were carried out using compacted hot mix asphalt samples with quartzite and metagranodiorite aggregates. Pipes with different surface area were used to flow water through the samples, and the processes were modeled using finite element method. The results clearly show the feasibility of the proposed method, and indicate the beneficial effects of higher thermal conductivity of aggregates and larger surface area of pipes. Velocity and thermal profiles of water in the pipe inside asphalt pavement are analyzed, and the necessity of good contact between asphalt mix...

- by Sankha Bhowmick
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- Environmental Science, Materials Science, Asphalt, Finite Element

We examined spatial patterns of trends in ice phenology and duration for 65 waterbodies across the Great Lakes region (Minnesota, Wisconsin, Michigan, Ontario, and New York) during a recent period of rapid climate warming (1975-2004). Average rates of change in freeze (3.3 d decade 21) and breakup (22.1 d decade 21) dates were 5.8 and 3.3 times more rapid, respectively, than historical rates (1846-1995) for Northern Hemisphere waterbodies. Average ice duration decreased by 5.3 d decade 21. Over the same time period, average fall through spring temperatures in this region increased by 0.7uC decade 21 , while the average number of days with snow decreased by 5.0 d decade 21 , and the average snow depth on those days decreased by 1.7 cm decade 21. Breakup date and ice duration trends varied over the study area, with faster changes occurring in the southwest. Trends for each site were compared to static waterbody characteristics and meteorological variables and their trends. The trend toward later freeze date was stronger in large, low-elevation waterbodies; however, freeze date trends had no geographic patterns or relationships to meteorological variables. Variability in the strength of trends toward earlier breakup was partially explained by spatial differences in the rate of change in the number of days with snow cover, mean snow depth, air temperature (warmer locations showed stronger trends), and rate of change in air temperature. Differences in ice duration trends were explained best by a combination of elevation and the local rate of change in either temperature or the number of days with snow cover.

- by John Magnuson
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- Earth Sciences, Environmental Science, Spatial Analysis, Limnology

An experimental investigation on natural convection in air in vertical convergent channels with wall uniform heat flux is presented. Wall temperatures show that by increasing the spacing the effect of the convergence angle decreases. For the lowest spacing, a significant decrease of maximum wall temperature occurs passing from the parallel vertical plate configurations to convergence angles h P 2 .

- by Oronzio Manca
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- Engineering, Visualization, Heat Transfer, Instrumentation

This paper provides realistic values of wind shear coefficients calculated using measured values of wind speed at 20, 30 and 40 m above the ground for the first time in Saudi Arabia in particular and, to the best of the authorsÕ knowledge, in the Gulf region in general. The paper also presents air density values calculated using the measured air temperature and surface pressure and the effects of wind shear factor on energy production from wind machines of different sizes. The measured data used in the study covered a period of almost three years between June 17, 1995 and December 1998. An overall mean value of wind shear coefficient of 0.194 can be used with confidence to calculate the wind speed at different heights if measured values are known at one height. The study showed that the wind shear coefficient is significantly influenced by seasonal and diurnal changes. Hence, for precise estimations of wind speed at a height, both monthly or seasonal and hourly or night time and day time average values of wind shear coefficient must be used. It is suggested that the wind shear coefficients must be calculated either (i) using long term average values of wind speed at different heights or (ii) using those half hourly mean values of wind speed for which the wind shear coefficient lies in the range P0 and 60.51. The air density, calculated using measured temperature and pressure was found to be 1.18 kg/m 3 . The air density values were also found to vary with the season of the year and hour of the day, and hence, care must be taken when precise calculations are to be made. The air density values, as shown in this paper, have no significant variation with height. The energy production analysis showed that the actual wind shear coefficient presented in this paper produced 6% more 0196-8904/$ -see front matter Ó energy compared to that obtained using the 1/7 power law. Similarly, higher plant capacity factors were obtained with the wind shear factor of 0.194 compared to that with 0.143.

- by Shafiqur Rehman
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- Saudi Arabia, Wind Power, Seasonality, Power Law

To accurately estimate near-surface (2 m) air temperatures in a mountainous region for hydrologic prediction models and other investigations of environmental processes, the authors evaluated daily and seasonal variations (with the consideration of different weather types) of surface air temperature lapse rates at a spatial scale of 10 000 km 2 in south-central Idaho. Near-surface air temperature data (T max , T min , and T avg ) from 14 meteorological stations were used to compute daily lapse rates from January 1989 to December 2004 for a medium-elevation study area in south-central Idaho. Daily lapse rates were grouped by month, synoptic weather type, and a combination of both (seasonal-synoptic). Daily air temperature lapse rates show high variability at both daily and seasonal time scales. Daily T max lapse rates show a distinct seasonal trend, with steeper lapse rates (greater decrease in temperature with height) occurring in summer and shallower rates (lesser decrease in temperature with height) occurring in winter. Daily T min and T avg lapse rates are more variable and tend to be steepest in spring and shallowest in midsummer. Different synoptic weather types also influence lapse rates, although differences are tenuous. In general, warmer air masses tend to be associated with steeper lapse rates for maximum temperature, and drier air masses have shallower lapse rates for minimum temperature. The largest diurnal range is produced by dry tropical conditions (clear skies, high solar input). Cross-validation results indicate that the commonly used environmental lapse rate [typically assumed to be Ϫ0.65°C (100 m) Ϫ1 ] is solely applicable to maximum temperature and often grossly overestimates T min and T avg lapse rates. Regional lapse rates perform better than the environmental lapse rate for T min and T avg , although for some months rates can be predicted more accurately by using monthly lapse rates. Lapse rates computed for different months, synoptic types, and seasonal-synoptic categories all perform similarly. Therefore, the use of monthly lapse rates is recommended as a practical combination of effective performance and ease of implementation.

- by Brian Harshburger
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- Seasonality, Atmospheric sciences, Applied, Land Surface Temperature

This paper presents the performance of a wire-on-tube heat exchanger of which the wire is an oscillating heat pipe. The experiments for this heat exchanger were performed in a wind tunnel by exchanging heat between hot water flowing inside the heat exchanger tubes and air stream flowing across the external surface. R123, methanol and acetone were selected as working fluids of the oscillating heat pipe. The inlet water temperature was varied from 45 to 85°C while the inlet air temperature was kept constant at 25°C. The results show that the oscillating heat pipe technique for all working fluids could increase around 10% of the heat transfer rate obtained from that without the refrigerant flow in the capillary tube when the inlet water temperature is at 60°C. Moreover, the heat transfer models for evaluating the heat exchanger effectiveness and the air-side heat transfer coefficient, are also developed in this work. These results of the models agreed very well with the experimental data.

- by Atipoang Nuntaphan
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- Mechanical Engineering, Heat Transfer, Performance, Heat Exchanger

This paper compares the performance of a low-cost green roof to a base case conventional insulated roof with the intent of discussing the interior behavior of a green roof in a semi-arid climate. All test cells were located in Pomona, California. Temperature data loggers were installed at various locations inside and outside all the test cells. The temperatures at all locations were recorded at half hour intervals from October through early January. Daily maximum temperatures during this time period ranged from around 93°F in earlier months to as low as 56°F in winter months. The analysis and comparison of the temperature data indicate that although it may not have as large a benefit as in other climates in the United States, a green roof will provide enough difference in interior air temperature during warm weather months to be beneficial in southern California. What's more, a green roof can still provide a more pleasant outdoor environment than paved, occupied roof spaces in a dry, sunny climate.

- by Miriam Figueroa
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- Los Angeles, United States, Air Temperature, Data Logger

The aim of this study was to evaluate how the summer and winter conditions affect the photosynthesis and water relations of well-watered orange trees, considering the diurnal changes in leaf gas exchange, chlorophyll (Chl) fluorescence, and leaf water potential (Ψ) of potted-plants growing in a subtropical climate. The diurnal pattern of photosynthesis in young citrus trees was not significantly affected by the environmental changes when compared the summer and winter seasons. However, citrus plants showed higher photosynthetic performance in summer, when plants fixed 2.9 times more CO 2 during the diurnal period than in the winter season. Curiously, the winter conditions were more favorable to photosynthesis of citrus plants, when considering the air temperature (< 29 ºC), leaf-to-air vapor pressure difference (< 2.4 kPa) and photon flux density (maximum values near light saturation) during the diurnal period. Therefore, low night temperature was the main environmental element changing the photosynthetic performance and water relations of well-watered plants during winter. Lower whole-plant hydraulic conductance, lower shoot hydration and lower stomatal conductance were noticed during winter when compared to the summer season. In winter, higher ratio between the apparent electron transport rate and leaf CO 2 assimilation was verified in afternoon, indicating reduction in electron use efficiency by photosynthesis. The high radiation loading in the summer season did not impair the citrus photochemistry, being photoprotective mechanisms active. Such mechanisms were related to increases in the heat dissipation of excessive light energy at the PSII level and to other metabolic processes consuming electrons, which impede the citrus photoinhibition under high light conditions.

- by Rafael Ribeiro
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- Plant Biology, Ecophysiology, Environmental Change, Seasonality

We compared below-canopy and open-site climatic conditions for 14 different forest sites in Switzerland and analysed the forest influence on local summer and winter climate according to the forest type (coniferous, mixed, deciduous), soil type, slope orientation, basal area and tree height. We compared below-canopy and open-field data for minimum, maximum and daily mean temperature, relative humidity, maximum and daily mean photosynthetically active radiation (PAR) and wind speed from 1998 to 2007. We found clear differences between below-canopy and open-field temperatures, humidity, wind speed and PAR and could relate them to the specific site conditions and forest type. The forest influence on PAR and maximum temperature is clearly determined by the forest type, whereas the influence on minimum temperature is affected by both forest type and slope orientation and impact on humidity depends on the soil type. The wind speed is most impacted by topography and slope orientation.

- by John Innes and +1
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- Earth Sciences, Climate, Biometeorology, Biological Sciences

This paper presents an evaluation of thermal comfort in an extended road trial study. Automobile seats play an important role in improving the thermal comfort. In the assessment of thermal comfort in autos, in general subjective and objective measurements are used. Testing on the road is very difficult but real traffic conditions affect the comfort level directly, as well as the driver's experience to real conditions. Thus, for such cases real traffic situations should not be neglected in the evaluation of comfort. The aim of this study was to carry out, on an extended road trial study, an evaluation of thermal comfort using human subjects. In the experiments used, the 100% polyester seat cover had three different cover materials, which were velvet, jacquard and micro fiber. All experiments were carried out on a sunny day with ten participants over 1 h. They were carried out at air temperatures of 25 1C in a Fiat Marea 2004, which had an automatic climate function. Skin temperature at eight points and skin wettedness at two points on the human body were measured during the trials. Participants were required to complete a questionnaire of 15 questions, every 5 min.

- by Fatih Babalik
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- Ergonomics, Textiles, Applied Ergonomics, Human Body

Abstract. Chemical and biological sedimentary records of a high alpine lake were used to reconstruct palaeoecological conditions and compared with two centuries of instrumental temperature measure-ments. Air temperature determined the... more

- by Roland Psenner and +1
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- Climate Change, Multidisciplinary, Atmospheric deposition, Time Delay

Water use in vineyards is controlled by energy absorbed by plants and the soil surface. An 8 day field experiment was conducted in a commercial vineyard near Lamesa, TX, to evaluate soil and canopy energy balances, and to examine energy exchange between canopy and soil. Grapevines in the vineyard were wrapped tightly to trellis wires, creating compact hedgerows that were 3 m apart and of 1.6 m height and 0.4 m width, with little foliage below 1 m above the soil surface. The Bowen ratio method was used to measure the vineyard energy balance including total latent heat flux (AE). Latent heat flux from the canopy (,~Ec) was determined from sap flow measurements of transpiration. Soil latent heat flux (AEs) was calculated as the difference between AE and AE c. These measurements were combined with measurements of soil net irradiance to partition the vineyard energy balance into soil and canopy components. During the study, AEs accounted for 44-68% of AE. Unstable conditions predominated during the study, with the soil generating sensible heat that was transferred to the canopy, producing values of AE c that were greater than canopy net irradiance. Within-row advection of sensible heat was 17-36% of AEc. Although the canopy was cooler than within-and above-canopy air, it was not a strong enough sink for sensible heat to produce stable conditions above the canopy. The narrow hedgerows created an unusual diurnal pattern of canopy net irradiance, having midmorning and midafternoon peaks, and a low midday plateau. Morning and afternoon peaks occurred during times of maximum direct beam irradiance on east and west sides of the hedgerows. Results also showed that within-canopy wind speed and air temperature were affected by wind direction.

- by Michael Savage
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- Earth Sciences, Biological Sciences, Energy Balance, Field Experiment

In Morocco, no operational system actually exists for the early prediction of the grain yields of wheat (Triticum aestivum L.). This study proposes empirical ordinary least squares regression models to forecast the yields at provincial and national levels. The predictions were based on dekadal (10-daily) NDVI/AVHRR, dekadal rainfall sums and average monthly air temperatures. The Global Land Cover raster map (GLC2000) was used to select only the NDVI pixels that are related to agricultural land. Provincial wheat yields were assessed with errors varying from 80 to 762 kg ha À1 , depending on the province. At national level, wheat yield was predicted at the third dekad of April with 73 kg ha À1 error, using NDVI and rainfall. However, earlier forecasts are possible, starting from the second dekad of March with 84 kg ha À1 error, at least 1 month before harvest. At the provincial and national levels, most of the yield variation was accounted for by NDVI. The proposed models can be used in an operational context to early forecast wheat yields in Morocco. #

- by Herman Eerens and +1
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- Applied Statistics, Crop Modeling, Weather Risks, Morocco

Today, many large commercial buildings use sophisticated building automation systems (BASs) to manage a wide range of building equipment. While the capabilities of BASs have increased over time, many buildings still do not fully use the BAS's capabilities and the BASs are not properly commissioned, operated or maintained, which leads to inefficient operation, increased energy use, and reduced lifetimes of the equipment. This report investigates the energy savings potential of several common heating, ventilation and airconditioning (HVAC) system re-tuning measures on a typical large office building prototype model, using the Department of Energy's building energy modeling software, EnergyPlus.

- by Srinivas Katipamula
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- Engineering, Energy Consumption, Energy Saving, Commercial Building

Daily stage data measured at the closing section of the Po River (Northern Italy), collected from historical archives of the “Hydrological Office of the Po River—Parma”, allowed to estimate daily discharges for the period 1807–1916, therefore to extend the time series of Po River discharges for 110 years before the actually published time series. This paper provides a detailed description of the stage–discharge conversion and of the tests performed for checking homogeneity of reconstructed data. In particular, monthly discharge data were compared with approximated catchment-average data of precipitation and evapotranspiration for the period 1831–2003, which were estimated, respectively, from monthly data of local precipitation (at Milan, Turin and Parma) and local air temperature (at Milan and Turin). It emerges that estimated values of precipitation, evapotranspiration and discharge provide a coherent picture of the hydrological dynamics in the basin throughout the study period. Specifically, an apparent progressive depletion of basin reservoirs is observed since 1920, i.e., when concomitant sudden changes (regime shifts) occurred in precipitation (downward shift) and evapotranspiration (upward shift). The 1920-shift is amongst the likely causes of the fact that prolonged drought periods as those observed in the 1940s and since 2003 are not observed in the pre-shift period, when accumulation of reservoirs occurred. The increase in peak-flow discharges observed in recent decades, with values well above the maximum discharge estimated for the nineteenth century as well as for the early twentieth century, is apparently the result of the massive levee works along the river network that were completed in the 1960s. On decadal time scales, discharge variability is found to essentially reflect the changes in precipitation patterns. In particular, peaks of comparable magnitude are found in the 128-month (∼11 years) wavelet spectra of precipitation and discharge. Furthermore, concurrent changes are observed in the persistence (i.e., autocorrelation) of precipitation and discharge data. Since the red-noise background spectrum of discharge is much lower than that of precipitation, river discharge is the likely hydrological variable to be preferred for assessing the basin’s response to the background climatic variability occurring at the decadal and multi-decadal time scales, notwithstanding the fact that changes in water management and other anthropogenic impacts can be important on long time scales. Concerning the seasonal to interannual response to climatic forcing, a robust dependence of wintertime precipitation and discharges on the state of the NAO was observed. This dependence results in stronger (weaker) precipitation and higher (lower) discharges during negative (positive) anomalies of the NAO index.

- by Soumyajit Sen
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- Time Series, Climate variability, Nineteenth Century, Multidisciplinary

This article presents a detailed study on the influence of winegrape variety, skin hardness of fresh berries, and withering thermo-hygrometric conditions on the dehydration kinetics of the grape. Although some works focused on the changes in the weight loss rate during grape dehydration under different environment conditions for several varieties, the combined effect of the skin mechanical properties and the thermo-hygrometric conditions has not been previously considered. The skin break force was confirmed as the varietal marker. Furthermore, its role in the selection of the withering conditions was assessed. The fresh grape berries were classified into two groups (soft and hard) according to the skin break force, and four off-vine withering conditions were evaluated. The softer skins facilitated the dehydration process increasing the weight loss rate, but the increase was significant only at low temperatures. The increase in temperature and/or decrease in relative humidity was beneficial to the grape dehydration process. A weight loss of about 50% after 12 days of withering was achieved at an air temperature of 28 C and relative humidity of 40%. Under the same dryer environmental conditions, a certain varietal effect on the dehydration kinetics was observed because a faster weight loss occurred for those grapes characterized by lower values of skin break force. These results suggest that the grape dehydration rate, influencing the quality of dessert wines, should be planned considering the skin hardness of fresh berries and the withering conditions. The skin break force represents a new variable that should be considered in modeling the withering process and in selecting, prior to harvest, the most appropriate vineyard for the dessert wines desired.

- by Alberto Caudana
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- Chemical Engineering, Drying Technology, Kinetics, Weight Loss