Thermohygrometric Index Research Articles

A comparative study of human thermal comfort conditions in two mountainous regions in Greece during summer

Human thermal comfort conditions were determined in two mountainous regions of Greece, Gerania mountains (MG) in east continental Greece, and mountainous Nafpaktia (MN) in west continental Greece. Both regions are unexploited with considerable tourist potential. Four sites in each study region were selected on the basis of different altitude. Air temperature and humidity, 1.5 m above ground surface, were recorded simultaneously every 15 minutes by sensors with dataloggers in selected sites between 23 June and 28 August 2007. Data of the above parameters were used for the calculation of the thermohygrometric index from which thermal comfort conditions were evaluated. Also, an artificial neural network model, was applied for the THI values evaluation at the highest examined altitudes based on the respective values of the lowest examined altitudes in both MG and MN. Results showed that from 09:00 to 20:00 h, MN was found to be more suitable, in relation to MG, for tourist and recreation activities at altitudes of 1338 m. At lower altitudes, both study regions could be proposed in an equal basis for the above activities during summer. Also, for the same period, thermal comfort conditions at the highest examined altitudes of MN and MG can accurately be predicted using artificial neural network models on the basis of those at lowest examined altitudes. From 21:00 to 08:00 h, MN can be considered clearly as a better tourist destination than MG.

北京北护城河河岸带的温湿度调节效应

PDF HTML阅读 XML下载 导出引用 引用提醒 北京北护城河河岸带的温湿度调节效应 DOI: 10.5846/stxb201201050023 作者: 作者单位: 中国科学院研究生院资源与环境学院,中国科学院研究生院,中国科学院研究生院资源与环境学院 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目(30870430);中国科学院知识创新工程重要方向项目(Y225016EA2);北京市自然科学基金资助项目(8132045) Effects of riparian buffers of North Mort of Beijing on air temperature and relative humidity Author: Affiliation: College of Resources and Environment,Graduate University of Chinese Academy of Sciences,College of Resources and Environment,Graduate University of Chinese Academy of Sciences,College of Resources and Environment,Graduate University of Chinese Academy of Sciences Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:以北京北护城河为例,探讨具有不同结构的河岸带对温湿度的调节效应。于2011年5-10月,根据河岸带在宽度、坡度、植物种类、植被覆盖度、距路距离和距路高度等结构指标上的差异,沿南北两岸各选取4类河岸带,并在与河岸带垂直的道路两侧分别设置相应的紧邻不同城市土地利用类型的对照区。在每月下旬的晴天或多云天,从8:00到18:00,对南北8类河岸带及其对照区的气温和相对湿度进行连续10 h的观测。t检验分析表明,与对照区相比,河岸带具有明显的温湿度调节效应,能有效地改善人体的舒适度。各类河岸带的气温极显著低于对照区,而相对湿度极显著高于对照区;河岸带的日气温和日相对湿度变化较对照区和缓,且存在季节差异,河岸带在春秋季表现出更明显的温湿度日极值调节效应。各类河岸带与其对照区在温湿指数上也存在显著差异:对照区在夏季均会使人体感到很不适,而河岸带南岸在6月和8月可有效地提高人体的舒适度,北岸在8月也可改善舒适度。同时,不同类型河岸带的温湿度调节效应也存在差异:南岸对温湿度的调节效应强于北岸,北岸气温显著高于南岸,而相对湿度显著低于南岸。差异显著性的多重比较表明,南北不同类型河岸带之间在温湿度上的差异随季节而异:5月和10月的差异较显著,但6-9月的差异不显著,这些与植被覆盖度、乔木密度、冠层结构、河岸带宽度、距路距离,以及周边土地利用方式有关。研究的结果可作为城市河岸带生态服务功能评价的一部分,并可为城市河岸带的建设、修复和管理提供依据。 Abstract:The study explored the effects of urban riparian buffers (RBs) with different structures on air temperature (T) and relative humidity (RH) in the North Mort of Beijing. From May to October in 2011, four RB types were selected on both the north and south RBs based on structural differences (such as width, slope, plant species, vegetation coverage, and distance and height to road). By both sides of the roads vertical to these RBs, the corresponding control areas (CAs) were set, adjacent to surrounding different urban land cover types. From 8:00 to 18:00, 10-hour measurements for T and RH were taken in different RB types and their CAs on sunny or cloudy days of late each month. Statistical analysis was used to test significance of differences in T, RH, and Thermohygrometric Index (THI) between RBs and CAs, between north and south RB types, and among different RB types and cross sectional zones. The results demonstrated that RBs had significant adjusting effects on T and RH compared with CAs, and could effectively improve human comfort. Firstly, from May to September, T and RH for RBs were extremely significantly lower and higher than those for CAs, respectively. Secondly, most daily variations in T for CAs showed a bimodal trend, but they had a single peak for RBs; the highest T for RBs occurred between 14:00 and 15:00, which was one hour later than that for CAs; RBs could significantly reduce the highest daily T, although it changed the lowest daily T little; meanwhile it could also effectively decrease high-temperature days. Thirdly, daily variations in T and RH for RBs were less than those for CAs. These differences depended on season, that is, the adjusting effects of RBs on microclimate range were especially strong in spring and autumn, but not in summer. Finally, THI for different RB types were significantly different from those for their CAs: all the CAs made human feel uncomfortable in the summer; the south RB types could effectively enhance human comfort level in June and August, and the north RB types could also do that in August. The results also showed that differences in adjusting effects on T and RH also existed in different RB types. Firstly, south RBs had stronger adjusting effects than north RBs, that is, T and RH for the north RB types were significantly higher and lower than those for the south RB types, respectively. It was mainly due to tree density, canopy structure, and riparian width. The wider south RB with higher tree density and denser upper canopy could partly block direct solar radiation. Secondly, the differences in T and RH among different RB types changed with seasons: there were significant differences in May and October, but not from June to September, related to vegetation coverage, riparian width, distance to the road, and surrounding land cover types. When vegetation coverage was higher than a certain threshold, its increase would not obviously influence T and RH for RB. Wider RB with open surroundings and larger distance to road would lead to stronger effects on microclimate. Finally, the differences in THI among different RB types were almost the same as those in T. In addition, there were no significant differences among different cross sectional zones within each RB type because of the limited RB width. The study may play an essential role on ecosystem service assessment of urban riparian buffer, and further provide theoretical basis for the planning, restoration and management of urban riparian buffers. 参考文献 相似文献 引证文献

Comparisons of urban and rural heat stress conditions in a hot–humid tropical city

Background: In recent years the developing world, much of which is located in the tropical countries, has seen dramatic growth of its urban population associated with serious degradation of environmental quality. Climate change is producing major impacts including increasing temperatures in these countries that are considered to be most vulnerable to the impact of climate change due to inadequate public health infrastructure and low income status. However, relevant information and data for informed decision making on human health and comfort are lacking in these countries.Objective: The aim of this paper is to study and compare heat stress conditions in an urban (city centre) and rural (airport) environments in Akure, a medium-sized tropical city in south-western Nigeria during the dry harmattan season (January–March) of 2009.Materials and methods: We analysed heat stress conditions in terms of the mean hourly values of the thermohygrometric index (THI), defined by simultaneous in situ air temperature and relative humidity measurements at both sites.Results: The urban heat island (UHI) exists in Akure as the city centre is warmer than the rural airport throughout the day. However, the maximum UHI intensity occurs at night between 1900 and 2200 hours local time. Hot conditions were predominant at both sites, comfortable conditions were only experienced in the morning and evenings of January at both sites, but the rural area has more pleasant morning and evenings and less of very hot and torrid conditions. January has the lowest frequency of hot and torrid conditions at both sites, while March and February has the highest at the city centre and the airport, respectively. The higher frequencies of high temperatures in the city centre suggest a significant heat stress and health risk in this hot humid environment of Akure.Conclusions: More research is needed to achieve better understanding of the seasonal variation of indoor and outdoor heat stress and factors interacting with it in order to improve the health, safety, and productivity of Akure city dwellers.

Hydrolyzable and fermentable carbohydrates in North Italian pastures for horses

Digestive and metabolic disorders in the horse were previously associated with hydrolyzable and nonhydrolyzable but rapidly fermentable components of nonstructural carbohydrates, particularly fructans. Aim of the study was to assess the contribution of the carbohydrate fractions to the composition of pastures in specific areas of Italy ordinarily designed for horses feeding. Seventy-seven samples from 11 pastures differing for floristic composition were collected across two growing seasons from April 18th2008 to May 10th2009 in the foothills (380 m a.s.l.) of the province of Parma (Italy). All samples were collected during the vegetative growth phase. To identify the bioclimatologic conditions of the growth, the average fortnightly thermohygrometric index (THI) was used. Slow fermentable carbohydrates mean concentration (NDF: 510.6, ADF: 274.7, ADL: 31.5 g/kg DM) reflected the typical chemical composition of high-quality grass and grass-legume mixtures. Among the nonstructual carbohydrates (NSC: 199.9 g/kg DM), hydrlolyzable carbohydrates content accounted for about the 18%. Nonhydrolyzable but rapidly fermentable carbohydrates were constituted for about the 23% by fructans (37.7 g/kg DM, range 15.5 to 138.2). The environmental conditions significantly affected the carbohydrate concentration in forages. Among NSC, fructans concentration in pastures was affected by bioclimatologic conditions (P<0.05). The floristic composition influenced the fructans content at a lesser extent. These results indicate a high variability of fructans concentration and reflect what previously observed in other areas. In any case the high levels observed for fructans in some geographic areas are not been achieved. Further interdisciplinary studies in this area between veterinarians and forage researchers are clearly warranted.

Air temperature and thermal comfort conditions in mountainous and urban regions

The present study explored air temperature and thermal comfort conditions in mountainous region of Nafpaktia (Municipality of Apodotia, Prefecture of Aitoloakarnania), a region without important commercial, industrial or other activities in west continental Greece, and in Athens, a metropolitan urban center in southeast continental Greece. There were 11 study sites in the case of Nafpaktia (676–1455 m altitude), areas with different altitude, ground cover, plant species and plant density. There was one study site in Athens (30 m altitude) nearby a densely built area, under the pressure of industrial activities and heavy traffic. Air temperature and humidity, 1.5 m above ground surface, were monitored simultaneously every 15 min in each site for the period between 1 July and 31 August 2006. Air temperature and relative humidity data were used for the calculation of the thermohygrometric index (THI) from which thermal comfort conditions were evaluated. For this work, two sites of mountainous Nafpaktia region (MNR), one characterized by the lower (fir and chestnut forest area) and the other by the higher (Evinos River area) average THI value, are presented. Results showed that MNR provided clearly improved air temperature and thermal comfort conditions in comparison to Athens in the study period. Fir and chestnut forest area was more beneficial, from a bioclimatological point of view, compared to Evinos River area. Therefore, fir and chestnut forest area should be further supported as a reliable alternative tourist destination for rest and recreation.

Is summer becoming more uncomfortable at Indian cities?

The recent decades have witnessed significant increase in temperatures both on global and regional scale. Some specific locations in India like Orissa and Andhra Pradesh have experienced unusually heat wave conditions resulting in increase in heat stress associated illnesses and mortality. There is a general belief that cities have become more uncomfortable during summer, particularly in the recent years. The present study is an attempt to examine the trend in discomfort over the Indian cities measured by an index (Thermo-Hygrometric Index: THI). Results show that in general there is an increasing trend in the discomfort from the last 10 days of April to June over most of the Indian cities. Further, frequency and maximum length of continuous periods exceeding abnormal discomfort values over a number of stations are steadily increasing particularly during May and June.

Determination of bioclimatic comfort in three different land uses in the city of Erzurum, Turkey

This study was carried out to determine the human bioclimatic conditions in rural, urban and urban forest areas in the conditions of the city of Erzurum, where an extreme continental climate type prevails. Data were obtained over a 10-month period and human bioclimatic conditions in these three different land-use types were evaluated using human bioclimatic indices, suitable for the data obtained. In the study, thermohygrometric index (THI), which assesses air temperature and relative humidity, and “beer garden days” index, which uses the days when temperature at 21:00 is over 20 °C, were used. While in these three areas “hot” and “comfort” ranges were determined to be 10% of the period, the number of “beer garden” days was only 20 days in rural, 15 days in urban forest and 18 days in urban areas of Erzurum. Consequently, it has been determined that the most suitable area for the human comfort in the conditions of Erzurum is in the urban area which is followed by the urban forest and the rural areas, both for each observation time and across the whole period.

The use of a complex thermohygrometric index in predicting adverse health effects in Athens.

Mortality and morbidity indices are known to depend on changes in meteorological conditions. In Athens, severe adverse health effects following extreme heat conditions have been reported. The usefulness has been investigated of the complex thermohygrometric index (THI), a simple index based on maximum daily temperature and relative humidity, in predicting the health effects of specific meteorological conditions. The values of THI were found to correlate well with more complex bioclimatic indices; the THI could successfully replace temperature and humidity in predicting the daily number of deaths through multiple linear regression modelling. Thus the introduction of THI levels more than 28.5 degrees C and between 26.5 and 28.5 degrees C, through dummy variables, in a regression model explained 40% of the variability in the number of deaths during the months of July and August. During days with THI values less than 26.5 degrees C the mean number of deaths was 33.5, compared to 41.8 when THI was between 26.5 and 28.5 degrees C. The daily number of deaths increased to 108.2 when THI exceeded 28.5 degrees C. From this study, the exact level of THI at which public health measures must be taken was not clear and more work is needed to identify it. However, given its simplicity, the use of THI for predicting meteorological conditions which are adverse to health would appear to be promising in preventive medicine and in health services planning.