This paper discussed the urban heat island (UHI) intensity and local air quality by using observational data of project of the System of Air Quality Forecasting and Research (SAFAR) over Delhi during the month of May ...This paper discussed the urban heat island (UHI) intensity and local air quality by using observational data of project of the System of Air Quality Forecasting and Research (SAFAR) over Delhi during the month of May and December 2013. It is found that UHI magnitudes ~2.2°C and ~1.5°C are formed at the evening traffic hours during May and December respectively. Also, intensity of UHI °C over daytime is referred as Urban Cool Island (UCI) during May and December. The diurnal PM2.5 concentration shows a bimodal pattern with peaks at morning and evening traffic hours during May and December. The planetary boundary layer height (PBLH) values show higher in magnitude during the daytime and lower in magnitude during the night-time. Whereas, the Ground Heat Flux values are lower during the daytime and higher during the night-time. The wind speed shows lower values during the UHI and higher magnitudes during the UCI formation hours. Concentration of PM2.5 and wind speed shows a strong negative correlation during May (r = -0.56, p = 0.002) and December (r = -0.57, p = 0.001) at C V Raman (CVR) site, however, high values in the concentration of PM2.5 during the low wind speed favour the condition for the formation of UCI. The regression analysis indicated that PM2.5 plays a significant role in the daytime cooling and nighttime warming over the urban areas during the low wind speed condition.展开更多
Heat balance of urban ecosystem is a key point for the study of urban climate and micro-climate pattern and its change mechanism. Urban heat island effect is becoming increasingly serious,which is mainly caused by the...Heat balance of urban ecosystem is a key point for the study of urban climate and micro-climate pattern and its change mechanism. Urban heat island effect is becoming increasingly serious,which is mainly caused by the change of the earth's surface cover and the anthropogenic heat release. In this study,the simulation experiment for the anthropogenic heat release was designed according to the heat balance principle. A set of buildings of miniature city were used to constitute the residential area,U grooves were applied to simulate the single building,and the fluorescent lamps in the U groove were regarded as the heat sources of the anthropogenic heat release. The simulation experiment was launched with long-short wave sun photometer,sonic anemothermometer and heat flow gauge in the experiment site. Then the net solar radiation,sensible heat flux and heat flux into the ground were determined. The quantities of the anthropogenic heat release were calculated based on the heat balance principle,and were compared with the theoretical power consumption of the fluorescent lamps. The root mean square error( RMSE) of the simulation for the anthropogenic heat release reaches0. 078 W·m- 2,a comparatively high precision,which showes that the anthropogenic heat release can be accurately determined through the simulation experiments. This study provided a scientific method for the purpose of monitoring the anthropogenic heat release.展开更多
Cooling principle is adopted in roadbed constructions in permafrost regions on the Qinghai-Tibet Plateau for protecting the underlying permafrost. One way is to use duct-ventilated emban kment. Based on ground tempera...Cooling principle is adopted in roadbed constructions in permafrost regions on the Qinghai-Tibet Plateau for protecting the underlying permafrost. One way is to use duct-ventilated emban kment. Based on ground temperature data collected along experimental emban kments in Beiluhe section of the Qinghai-Tibet Railway, engineering effects of duct-ventilation for protection of the permafrost beneath the emban kment were studied. Analyses of ground temperature changes and heat inlux indicate that ventilation ducts effectively cool the soils surrounding the ducts in the emban kment and that yearly heat collection of the ambient soils appears as heat release. Permafrost behaviour beneath conventional emban kment and test emban kments with ducts installed at a high and low positions were studied to determine temperature-changing tendency during three years. Where the permafrost under the conventional emban kment and the duct high-positioned emban kment decreasingly absorbs heat during the period. The ground temperature of the permafrost under the conventional emban kment rises and that under the high-positioned emban kment decreases slightly. The temperature of the permafrost under the duct low-positioned emban kment decreased remarkable due to release of heat. These findings demonstrate that ventilated emban kments with low-positioned ducts produce beneficial temperature-controlling effects that actively cool the roadbed soils and keep the roadbed thermally stable. Accordingly, they were strongly recommended for use in the construction of emban kments in the permafrost regions on the plateau.展开更多
文摘This paper discussed the urban heat island (UHI) intensity and local air quality by using observational data of project of the System of Air Quality Forecasting and Research (SAFAR) over Delhi during the month of May and December 2013. It is found that UHI magnitudes ~2.2°C and ~1.5°C are formed at the evening traffic hours during May and December respectively. Also, intensity of UHI °C over daytime is referred as Urban Cool Island (UCI) during May and December. The diurnal PM2.5 concentration shows a bimodal pattern with peaks at morning and evening traffic hours during May and December. The planetary boundary layer height (PBLH) values show higher in magnitude during the daytime and lower in magnitude during the night-time. Whereas, the Ground Heat Flux values are lower during the daytime and higher during the night-time. The wind speed shows lower values during the UHI and higher magnitudes during the UCI formation hours. Concentration of PM2.5 and wind speed shows a strong negative correlation during May (r = -0.56, p = 0.002) and December (r = -0.57, p = 0.001) at C V Raman (CVR) site, however, high values in the concentration of PM2.5 during the low wind speed favour the condition for the formation of UCI. The regression analysis indicated that PM2.5 plays a significant role in the daytime cooling and nighttime warming over the urban areas during the low wind speed condition.
基金supported by the National Natural Science Foundation of China ( No. 40971187 and 41472243 )the Funded By Open Research Fund Program of Key Laboratory of Digital Mapping and Land Information Application Engineering,National Administration of Surveying,Mapping and Geoinformation ( No. GCWD201402 )
文摘Heat balance of urban ecosystem is a key point for the study of urban climate and micro-climate pattern and its change mechanism. Urban heat island effect is becoming increasingly serious,which is mainly caused by the change of the earth's surface cover and the anthropogenic heat release. In this study,the simulation experiment for the anthropogenic heat release was designed according to the heat balance principle. A set of buildings of miniature city were used to constitute the residential area,U grooves were applied to simulate the single building,and the fluorescent lamps in the U groove were regarded as the heat sources of the anthropogenic heat release. The simulation experiment was launched with long-short wave sun photometer,sonic anemothermometer and heat flow gauge in the experiment site. Then the net solar radiation,sensible heat flux and heat flux into the ground were determined. The quantities of the anthropogenic heat release were calculated based on the heat balance principle,and were compared with the theoretical power consumption of the fluorescent lamps. The root mean square error( RMSE) of the simulation for the anthropogenic heat release reaches0. 078 W·m- 2,a comparatively high precision,which showes that the anthropogenic heat release can be accurately determined through the simulation experiments. This study provided a scientific method for the purpose of monitoring the anthropogenic heat release.
文摘Cooling principle is adopted in roadbed constructions in permafrost regions on the Qinghai-Tibet Plateau for protecting the underlying permafrost. One way is to use duct-ventilated emban kment. Based on ground temperature data collected along experimental emban kments in Beiluhe section of the Qinghai-Tibet Railway, engineering effects of duct-ventilation for protection of the permafrost beneath the emban kment were studied. Analyses of ground temperature changes and heat inlux indicate that ventilation ducts effectively cool the soils surrounding the ducts in the emban kment and that yearly heat collection of the ambient soils appears as heat release. Permafrost behaviour beneath conventional emban kment and test emban kments with ducts installed at a high and low positions were studied to determine temperature-changing tendency during three years. Where the permafrost under the conventional emban kment and the duct high-positioned emban kment decreasingly absorbs heat during the period. The ground temperature of the permafrost under the conventional emban kment rises and that under the high-positioned emban kment decreases slightly. The temperature of the permafrost under the duct low-positioned emban kment decreased remarkable due to release of heat. These findings demonstrate that ventilated emban kments with low-positioned ducts produce beneficial temperature-controlling effects that actively cool the roadbed soils and keep the roadbed thermally stable. Accordingly, they were strongly recommended for use in the construction of emban kments in the permafrost regions on the plateau.
