Vertical Distribution Of Air Temperature Research Articles

Striking impacts of biomass burning on PM2.5 concentrations in Northeast China through the emission inventory improvement

Biomass burning exerts substantial influences on air quality and climate, which in turn to further aggravate air quality. The biomass burning emissions in particular of the agricultural burning may suffer large uncertainties which limits the understanding of their impact on air quality. Based on an improved emission inventory of the Visible Infrared Imaging Radiometer Suite (VIIRS) relative to commonly used Global Fire Emissions Database (GFED), we thoroughly evaluate the impact of biomass burning on air quality and climate during the episodes of November 2017 in Northeast China which is rich in agriculture burning. The results first indicate substantial underestimates in simulated PM2.5 concentrations without the inclusion of biomass burning emission inventory, based on a regional air quality model Weather Research and Forecasting model and Community Multiscale Air Quality model (WRF-CMAQ). The addition of biomass burning emissions from GFED then reduces the bias to a certain extent, which is further reduced by replacing the agricultural fires data in GFED with VIIRS. Numerical sensitivity experiments show that based on the improved emission inventory, the contribution of biomass burning emissions to PM2.5 concentrations in Northeast China reaches 32%, contrasting to 15% based on GFED, during the episode from November 1 to 7, 2017. Aerosol direct radiative effects from biomass burning are finally elucidated, which not only reduce downward surface shortwave radiation and planetary boundary layer height, but also affect the vertical distribution of air temperature, wind speed and relative humidity, favorable to the accumulation of PM2.5. During November 1–7, 2017, the mean daily PM2.5 enhancement due to aerosol radiative effects from VIIRS_G is 16 μg m−3, a few times higher than that of 2.8 μg m−3 from GFED. The study stresses the critical role of biomass burning, particularly of small fires easily missed in the traditional low-resolution satellite products, on air quality.

Can the ERA5 Reanalysis Product Improve the Atmospheric Correction Accuracy of Landsat Series Thermal Infrared Data?

Atmospheric correction is a key step toward estimating land surface temperature from the sensor with only one thermal infrared (TIR) channel. We use ground radiosounding profiles collected from 163 radiosonde observations to provide insights on how well the ERA5 reanalysis product performs in the atmospheric correction of Landsat series TIR data. Despite the poor performance of the ERA5 product for estimating atmospheric upward radiance, downward radiance, and transmittance of Landsat series TIR data in the Americas and Africa, the performance of the ERA5 product was superior to that of the M2I6NPANA (inst6_3d_ana_Np) dataset (MERRA2) and (Final) Operational Global Analysis data (FNL) products in Asia and Europe. The vertical distribution of air temperature and relative humidity profiles may explain the poor performance of ERA5 in the Americas and Africa. This letter shows the advantages and weaknesses of the ERA5 reanalysis product in the atmospheric correction of Landsat series TIR data and will benefit research fields that require an atmospheric profile as input.

Experimental study of vertical air temperature distribution and ventilation with energy saving using solar chimney

Demands for residential and commercial buildings are increasing with a rapidly growing population. As a result, the buildings will expand vertically and need proper ventilation and temperature distribution inside. In conventional architecture, natural ventilation is not sufficient to meet the needs of ventilation and space conditioning, so fans and air conditioners are necessary. These devices consume 40%-60% of total energy. This can reduce with the help of a solar chimney. In most studies on solar chimneys, the emphasis has been on improving the ventilation performance in ideal conditions, whereas experimental studies have been mainly confined to small equipment. Present work carried out experimental studies on a ventilation system with full scale solar chimneys to determine the ventilation performance in an actual building space in Bhopal, India. A test space connected to a rooftop solar chimney is used for research work. It is possible to tilt the chimney from a horizontal to a vertical position at any angle. In this research work, for effective utilizing the solar radiation, the solar chimney was kept at an angle of 30° with the sun facing. Temperature distribution and air ventilation have been compared in a test space with and without solar chimney. The results show that the distribution is better and improvement in ventilation is up to 20 % with the use of solar chimney in the summer season. It was also noticed from the results of the test space that electric energy of 1kWh can be saved per day using a solar chimney.

Maximum and minimum air temperature lapse rates in the Andean region of Ecuador and Peru

AbstractTo know the vertical distribution of air temperature is complex, and this is necessary for different applications. The main explanatory variable of air temperature is elevation above sea level, whose relationship with air temperature is measured by air temperature lapse rates (LRs). LRs can vary considerably spatiotemporally due to a wide spectrum of geographical, environmental, and other atmospheric factors. Our study presents the first comprehensive assessment of spatiotemporal changes of LRs over the Tropical Andes. Our study is focused on the Peruvian and Ecuadorian Andes, divided in two subregions by the parallel 9.5° (i.e., north and south). Maximum and minimum air temperatures were employed from 115 quality checked weather stations, for the period 1994–2011. Maximum (LRmax) and minimum (LRmin) air temperature lapse rates have been calculated for the whole study period. The effects of seasonality, humidity content and ENSO on the variability of LRs have been analysed. Results show that LRs have large spatiotemporal variability, since references values of LRmax range from −3.57 (South, dry season) to −4.77 (North, wet season), and LRmin range from −3.78 (North, dry season) to −4.93°C·km−1 (South, dry season), in function of season and subregion. Results indicate that the ENSO phases contribute significantly to the variability of southern subregion LRs. This study also presents that minimum air temperatures were more unpredictable than maximum air temperatures in terms of error and uncertainty, as a consequence of the larger spatial variability of nocturnal air temperatures, mainly influenced by local topography. In conclusion, this work goes deeper into the need to obtain precise LRs adapted to the study region, and shows that the use of standard LR values can cause significant failures in modelling air temperature in regions of complex terrain, such as the Andes.

Evaluation of passive cooling methods to improve microclimate for natural ventilation of a house during summer

Evaporative cooling is a widely used passive cooling method to mitigate high ambient temperatures in Japan during the hot and humid summer season. An evaporative cooling louver was developed by Hirayama et al. (2014) to create a cool microclimate in an urban residential outdoor space. This study investigated the potential of using passive cooling methods integrated with the louver to create a cool microclimate in a semi-outdoor space for natural ventilation. A field measurement was conducted to evaluate the microclimate in a semi-outdoor space under different amounts of solar radiation, surrounding vegetation, and distances from louver to window to find the best way that accumulates at most the cool air generated by the louver. Best results were found when the semi-outdoor space was exposed to low solar radiation, was fully surrounded by vegetation, and when the louver was closer to the window. Moreover, to use the cool microclimate created at the semi-outdoor space for natural ventilation, different ventilation settings such as window opening area, indoor cross ventilation, and stack ventilation with a sky window were incorporated and measured to find the best conditions to induce the cool air into the indoor space. Best results were found when the window was fully open and the wind speed of the air crossing the window was more than 0.2 m/s, which maintained a cooler vertical air temperature distribution inside the window.

C-24 暖房空間の垂直温度分布の簡易計算法 : その2.上部吹出し・下部吸込み方式における計算モデルとその検証

C-24 暖房空間の垂直温度分布の簡易計算法 : その2.上部吹出し・下部吸込み方式における計算モデルとその検証

地窓を利用した夜間自然換気による潜熱蓄熱材の蓄冷効果に関する研究

1. Introduction In this paper, we focused on introduction of phase change material(PCM) into a house to secure a cold storage with night natural ventilation. We conducted measurement in order to understand indoor thermal characteristics in a room with night natural ventilation for introducing PCM on the floor of a house to maximize cooling effect. Measurement was mainly conducted for on a room of the full-scale house where it has two openings at floor level. We measured vertical air temperature distribution and inflow wind speed to understand indoor thermal characteristics. And heat flow was also measured on the floor and under the floor to reveal cold storage mechanism. 2. Categorization We categorized measurement results according to weather condition on each day as follows. 1) Day of large air temperature difference between indoor and outdoor(ΔT) with high inflow wind speed, 2) Day of large ΔT with low inflow wind speed, and 3) Day of small ΔT with high inflow wind speed. 3. Measurement summary on indoor thermal characteristics Vertical air temperature distribution of indoor was influenced by inflow wind speed and ΔT. In case that inflow wind speed was lower than 0.1m/s, cold air accumulated along the floor was not mixed with the air at upper area of indoor. In case that inflow wind speed was over 0.1m/s and under 0.3m/s, inlet air mixed with indoor air. At this time, mixing height was determined by ΔT and inflow wind speed. In case that inflow wind speed was over 0.3m/s, indoor air was entirely mixed with outdoor air, thus vertical air temperature distribution tended to be disappeared. 4. Measurement summary on cold storage Cold storage tended to be proportional to ΔT. Cold storage accelerated as the condition of large ΔT and low inflow wind speed because cold air accumulated along the floor was not mixed with upper air of indoor. In case that air temperature near the floor was 2°C lower than phase change temperature of PCM for solidification, latent cold storage begun to progress. Cold storage ratio of latent heat was averagely 70%, and total cold storage tended to change approximate 1.5 times depending on outdoor air temperature. 5. Conclusion Indoor thermal characteristics and cold storage rate were changed by ΔT and inflow wind speed. In some cases, latent cold storage efficiency of PCM on the floor with night natural ventilation was confirmed. In the future, considering the daily life activity of residents, we are going to research passive cooling effect of PCM including the day time. Also, in order to develop a numerical simulation tool for designing a passive cooling house with PCM including a calculation model of vertical air temperature distribution, we will determine the parameter of turbulence diffusion coefficient by CFD simulation.

Thermal Comfort in Naturally Ventilated Apartments in Surabaya, Indonesia

This study aims to investigate the detailed thermal environments in apartments of Surabaya, Indonesia and discuss their potential passive cooling strategies. Major thermal parameters, vertical distribution of air temperature and surface temperature of walls/ceiling were measured in one of the representative units of three types of apartments respectively, under different natural ventilation conditions. The results revealed that the unit in the old public apartment showed better thermal environments compared to those in the other two apartments. It is very difficult to achieve thermal comfort during most of the day particularly in the new public and private apartments by means of natural ventilation alone. Building orientation, insufficient shading devices, and building materials are some of the factors causing hot conditions particularly in the newly emerging middle-class apartments. Several passive cooling strategies were proposed based on the measurement results.

Study of the Vertical Distribution of Air Temperature in Warehouses

Warehouses are usually large, plain industrial buildings commonly used for storage of goods. Vertical distribution of air temperature is an important aspect for indoor environment design, which must be taken into account by architects and engineers in the early stages of warehouse design. The aim of this work is to analyze the vertical temperature gradients existing in warehouses, quantifying their value and analyzing their evolution along the year. To do so, the study outlines the monitoring of several warehouses with different building typology and height located in different areas of Spain for a complete annual cycle. The results obtained when applying a simple linear regression analysis to 175,200 vertical temperature profiles show that there is a strong influence of the outdoor temperature over the stratification of the indoor air. During warm months, the ceiling and the upper strata get warmer, whereas the cold air accumulates in the lower levels, increasing the stratification of indoor air (maximum values between 0.3 °C/m and 0.7 °C/m). During cold months, the ceiling gets cold due to its contact with the outdoor air, therefore, the colder, heavier air moves down to the lower strata, registering insignificant vertical temperature differences. Air conditioning of the warehouse, besides controlling the temperature, limits the influence of the outdoor environment on the stratification of temperatures. The results of the study may be of great use for warehouses for products sensitive to temperature, which may suffer a different evolution, conservation or maturation when the temperature differences are maintained for a long time.

Experimental study including subjective evaluations of mixing and displacement ventilation combined with radiant floor heating/cooling system

Sixteen subjects evaluated the indoor environment in four experiments with different combinations of ventilation systems and radiant heating/cooling systems. In the first two tests, the simulated residential room was equipped either by a mixing ventilation system supplying warm air for space heating or by a combination of radiant floor heating and mixing ventilation system. The vertical air temperature distribution was more uniform for floor heating. The discomfort due to cold feet/lower legs was higher for warm air heating, but no significant difference in thermal perceptions between the two mixing ventilation systems was found. The next two tests simulated an office room during summer, ventilated and cooled either by a displacement ventilation system alone or by a displacement ventilation system combined with radiant floor cooling. Displacement ventilation combined with floor cooling had lower floor temperature, warmer supply air, and less homogeneous vertical temperature profile, but it did not result in thermal discomfort on feet/lower legs or discomfort due to a vertical air temperature difference higher than for a displacement ventilation system alone, where the floor temperature was higher, supply air cooler, and vertical temperature profile more uniform.

Thermal Comfort Evaluation with Fireplace in Occupied Space

The solid fuel heaters are popular in Slovakia again, where about 50% of new freestanding homes have one. The classic fireplace, with a blazing fire open to the room as traditional symbol of comfort and security becomes with better building thermal insulation a primary rather than an occasional indulgence heat source. This paper reports the results of field measurement and simulation investigating the thermal comfort criteria in occupied space with fireplace heating system. The field study was performed in a small furnished living-room. The indoor surface temperatures were captured with infrared camera and the mean radiant temperatures were calculated by the ESP-r simulation tool. Thermal comfort prediction maps (PPD and PMV index) are presented to describe range of occupant comfort levels with mean air temperature, air velocity and clothing level variations. It was found that this system provide full area improved thermal climate only with high air temperature level. The study was limited to the case with no vertical air temperature distribution.

The effects that the temperature and main gas components of the atmosphere have on errors in measuring the atmospheric content of carbon dioxide with a correlation infrared radiometer

A spectral range of 920 to 960 cm−1 is chosen for satellite measurements of the CO2 content in the atmosphere with a correlation method. The optimal transmission function of the measured gas in the correlation channel of the radiometer is estimated. It is shown that the effects that atmospheric gases (H2O, CO, O3, N2O, and CH4) and errors in specifying the land-surface temperature and the vertical air-temperature distribution have on errors in measuring the CO2 content throughout the entire atmospheric thickness may reach several percent.

Modeling Thermal Stratification in Fan-Ventilated Greenhouses

A two-dimensional thermal model was developed to investigate the thermal stratification in fan-ventilated greenhouses. Model inputs include outside weather (air temperature, humidity, and solar radiation), geometric parameters of crop rows and leaf area index, greenhouse ground and roof temperatures, ventilation rate, and operation of evaporative cooling pads. Comparing predictions with observed data indicated that the air temperature and relative humidity were modeled at acceptable accuracies, with air temperature underpredicted by 1.3C and relative humidity overpredicted by 9%, on average for a planted greenhouse. For an unplanted greenhouse, the air temperature was predicted with an absolute error of 0.7C, while for relative humidity the absolute error was 3%. Vertical temperature variation, defined as maximum temperature minus minimum temperature at approximately the central location of greenhouse, was predicted with an absolute error of 0.1C and a relative absolute error of 10% for the planted greenhouse, while for an unplanted greenhouse it was 0.6C for the absolute error and 12% for the relative absolute error. Simulations with the model suggest that increasing ventilation rate reduced the vertical temperature gradient. Increased ventilation reduced air temperature more at the top than the bottom of the greenhouse. Greater air temperature variation was produced when using evaporative pad cooling than not. Air temperature was reduced more at the bottom than at the top with evaporative pad cooling. The presence of a canopy altered the vertical air temperature distribution and reduced the temperature variation. A sample simulation showed that on a typical summer day at Raleigh, North Carolina, the presence of a canopy row with a height of 1.75 m occupying 69% of the ground area reduced the air temperature variation from 11.5C to 1.8C in a fan-ventilated greenhouse operating with a ventilation rate of 0.087 m3 m-2 s-1 and using evaporative pad cooling. The peak air temperature generally occurred at the top of canopy or somewhat below the canopy top. This finding may have some significance in establishing the location of temperature control sensors in future control systems.

Effects of vertical air temperature distribution within forest canopies on photosynthesis and transpiration

This study examined whether accurately simulating vertical air temperature (AT) distribution within forest canopies is essential for predicting vertical photosynthesis and transpiration distribution using multilayer canopy models. Inspecting earlier observational studies that reported vertical AT distribution within forest canopies, we showed that the common vertical AT difference within forest canopies was lower than 3.0 °C. We showed, using a leaf-scale transpiration-photosynthesis model, that a 3. 0 °C AT difference caused smaller differences in leaf-scale photosynthesis and transpiration rates than a common vertical difference in photosynthetic active radiation (PAR) intensity within forest canopies when AT was higher than ca. 15 °C. While, the AT difference caused larger differences in leaf-scale photosynthetic and transpiration rates than the PAR difference when AT was lower than ca. 10 °C . However, the ranges in the rates with changing AT by 3.0 °C were comparable with predictability of a leaf-scale transpiration-photosynthesis model. Thus, we conclude that accurately simulating AT distribution is not essential at this stage for calculating vertical photosynthesis and transpiration distribution using multilayer canopy models.

On the variability and modelling of surface albedo and long-wave radiation components

Variability and modelling of surface albedo and long-wave radiation components are presented for grassland sites whose elevation ranged from 212 to 1489 m a.s.l. Data sets utilised for the study were recorded in south-west Germany during REKLIP (REgio KLIma Projekt), which extended from 1991 to 1996. Inter-annual variability of albedo α and outgoing long-wave radiation R l↑ at the study sites was less than 9%, thus, rendering the measured data quite suitable for diagnostic and modelling purposes. Annually, α extended from 22 (at 212 m a.s.l.) to 36% (at 1489 m a.s.l.), while R l↑ declined from 367 (at 212 m a.s.l.) to 326 W m −2 (at 1489 m a.s.l.). Consequently, radiation efficiency at the lowest elevated grassland site was approximately 1.3 times that of the highest elevated site. The observed decline in incoming long-wave radiation R l↓ with altitude relates physically to the vertical distribution of air temperature and green house gases (particularly atmospheric water vapour and CO 2). Ratio of annual R l↓ to R l↑ at the sites was about 0.87. While albedo dropped with cloud cover N at both low and high altitude sites in summer, there was, however, a noteworthy discrepancy in winter, when α declined with N at the low altitude location but increased with it at the high altitude location. Mean daily sums of R l↑ fell with N in summer, but rose with it in winter for both low and high altitude sites. In view of the major role played by altitude in regulating climate and radiative budget at the surface, we have extended Dong et al. model to include seasonal altitude terms for estimating grassland albedo. In addition, outgoing long-wave radiation under all sky conditions has been expressed here as a function of air temperature, absorbed short-wave radiation and altitude.

加圧式床吹出し居住域空調方式における二重床に関する研究

The results of the experiment on the air leakage prevention with the pressurized under floor air-conditioning are described for correct estimation of vertical air temperature distribution in the space. It was found that the air leakage must be less than 25% of supply air volume to maintain the vertical temperature differential within 2 degrees. A special chart on the control target for air leakage through the access floor with the circulation air volume of less than 25% is presented. The newly devised type of non-air leakage access floor is presented to give the temperature differential within 2 degrees.

加圧式床吹出し居住域空調方式の床吹出し口の特性に関する研究

For correct estimation of the vertical air temperature distribution with the pressurized under floor air-conditioning system for occupied zone during cooling operation, the air discharge angle of the twisted-groove type 200 φ floor-outlet, air leakage through access-floor, and the temperature difference between supply and return, were taken as the most influential factors on the vertical temperature distribution. A special chart is presented to set the control target for those three factors so as to give thermal comfort within the occupied zone. It was clarified that newly devised shutter of the floor outlet for this system would not change the discharge air velocity by manual operation of occupants, and thus the height reached by the discharged air would not vary.

Horizontal and vertical distribution of air temperature in a vegetation [maize] canopy.

Horizontal and vertical distribution of air temperature in a vegetation [maize] canopy.

大空間における上下温度分布の予測モデル : 大空間の空調・熱環境計画手法の研究 その1

In this paper we describe a simplified prediction model of the vertical air temperature distribution in a large space. This calculation model has the following characteristics ; (a) The large space is divided into multiple vertical zones. (b) Air flows caused by heat loss or heat gain through walls can be evaluated. (c) Air streams from outlets are calculated as nonisothermal jets. These results can be used to evaluate air flow rates between the upper zones and the lower zones of the large space. (d) Equations of heat flow and air flow volume of each zone are derived and the vertical air temperature distribution are calculated. The results of a study on the accuracy of this calculation model are presented along with the experiment results.

温風暖房空間の上下温度分布の簡易計算モデル : 空調空間の熱的特性に関する研究 第2報

In this paper we describe a simplified calculation model of vertical air temperature distribution during heating in the air-conditioned room, where air supply outlets are installed in the ceiling or the high sidewall and air return intake is installed in the low sidewall. The basic equations for the calculation are derived from a mixing process model of the room air, which is divided into complete mixing region at the upper side of the room and piston flow region at the lower side of one. It is assumed that in the former the discharged warm air is mixed with the room air completely, while in the latter the room air moves downward to the floor and its temperature gradient is formed only in the vertical direction of the room. Regression equations were derived from many experimental results for stepwise inputs of warmed air at the simulated full-scale office room. The equations give relation between the model parameter defined as a ratio of depth of the complete mixing region to the room height and Archimedes number which is induced from the supply air condition.