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Published in Splinter Robert, Illustrated Encyclopedia of Applied and Engineering Physics, 2017
[biomedical, energy, geophysics] Daily (diurnal cycle) or related to activity occurring primarily in the daytime (e.g., flowers closing at night) (also seecircadian rhythm) (see Figure D.50).
Evaluating the 3D cooling performances of different vegetation combinations in the urban area
Published in Journal of Asian Architecture and Building Engineering, 2022
Xing Tan, Jianjun Liao, Komi Bernard Bedra, Jiayu Li
It is worth describing some of the limitations of the current study which are mainly related to the ENVI-met model. One is that wind flow and cloudiness remain constant throughout the diurnal cycle simulation, which does not correspond to the real atmosphere (Morakinyo, Kong, and Lau et al. 2017). Furthermore, all building facades and roofs of ENVI-met use similar thermal performance as a single wall material, which oversimplifies the heterogeneity of the urban environment (Morakinyo, Kong, and Lau et al. 2017). Moreover, we only explored the cooling performance of different vegetation combinations. Further study is recommended to investigate the 3D cooling performance of different ratios of trees, shrubs, and grass.
Ozone exchange within and above an irrigated Californian orchard
Published in Tellus B: Chemical and Physical Meteorology, 2020
J.S. Brown, M.M. Shapkalijevski, M.C. Krol, T. Karl, H.G. Ouwersloot, A.F. Moene, E.G. Patton, J. Vilà-Guerau de Arellano
The O3 diurnal cycle reaches a peak at around 15:00 LT, following daytime ozone production and entrainment from the overlying free atmosphere (Fig. 2a). The O3 minimum coincides with the peak in NOx mixing ratios at 07:00 LT. O3 mixing ratios before irrigation are consistently higher than after irrigation, with this increase being more pronounced during the daytime. The O3 mixing ratios here are comparable to other rural regions in Central California during spring, with Fares et al. (2012) finding O3 mixing ratio above a Californian orange orchard of around 55 ppb in spring 2009, with daytime peaks in the summer exceeding 100 ppb.
Recent spatial gradients and time trends in Dhaka, Bangladesh, air pollution and their human health implications
Published in Journal of the Air & Waste Management Association, 2019
Md Mostafijur Rahman, Shakil Mahamud, George D. Thurston
Seasonal variation, day-of-week analysis, spatial gradients, and trends of PM2.5, PM10, SO2, NO2, CO, and O3 were investigated for the Dhaka metropolitan area for the period of 2013 to 2017. The diurnal cycles investigation was limited to only 2017 due to lack of availability of hourly data from 2013–2016. Ozone in Dhaka showed seasonal patterns different from those of other pollutants, which all showed distinct seasonal variation with a maximum during winter and a minimum during monsoon. The pollution concentration of PM2.5 and PM10 was increased about five- to sixfold during winter versus monsoon, while SO2, NO2, and CO concentrations were roughly two- to threefold increased during winter versus monsoon. Particulate matter (PM2.5 and PM10) showed nonattainment of BNAAQS during the nonmonsoon time of the year, whereas gaseous pollutants experienced a minimal number of BNAAQS exceedances throughout the study period, suggesting that gaseous pollutants in Dhaka are not as significant a health threat as PM. In the three Dhaka metropolitan area stations considered, fine particles dominated variations in the total PM mass during the winter season, while coarse particles dominated variations in the total PM mass during monsoons, likely due to reductions in the kiln emissions of fine PM2.5 during the monsoon. Unlike many other major cities in the world, day-of-week pollution patterns were not significant in Dhaka. The results of diurnal cycle analysis indicated that maximum pollution concentrations were observed at night, between 10 p.m. and 9 a.m., which is governed by long-route bus and heavy-duty truck flow during that time, as well as the reduced dispersive capabilities of the atmosphere at night (due to generally lower wind speeds and mixing heights at night). Homogeneous spatial distributions of PM were found across the Dhaka metropolitan area, while other pollutants showed nonhomogeneous patterns. Spatiotemporal variability of pollution concentrations was apparently a result of spatial and time variations in the major local anthropogenic sources of pollutions (i.e., brick kilns, industries, traffic) and their operation times.