Utilizing experimental data of the atmospheric surface layer in the Gobi Oasis of Jinta in a comparative study, we demonstrate that under the condition of unstable stratification, the normalization variances of temper...Utilizing experimental data of the atmospheric surface layer in the Gobi Oasis of Jinta in a comparative study, we demonstrate that under the condition of unstable stratification, the normalization variances of temperature in the oasis and Gobi Desert meetφs （z∧）= φθ（Z/∧） =αθ（-Z/ ∧）-1/3 while normalization variances of both humidity and CO2 in the oasis meet φ（Z/∧）= αs （1 - βs z /∧）-1/3 ; the normalization variance of temperature in the oasis is large due to disturbance by advection, whereas variance of CO2 in the Gobi Desert has certain degree of deviation relative to Monin-Obukhov （M-O） scaling, and humidity variance completely deviates from variance M-O scaling. The above result indicates that under the condition of advection, hu-midity variance meets the relation δ2 sm=D2 δ2SA ＋ δ2SB and it is determined by relative magnitude of scalar variance of ad- midity variance meets the relation δsm = D2δsA ＋ δsB vection transport. Our study reveals that, if the scalar variance of humidity or CO2 transported by advection is much larger than local scalar variance, observation value of scalar variance will deviate from M-O scaling; when scalar variance of advection transport is close to or less than local scalar variance, the observation value of scalar variance approximately meets M-O scal- ing.展开更多
The total number of atmospheric particle (AP) is an important datum for planetary science and geoscience. Estimating entire AP number is also a familiar question in general physics. With standard atmosphere model, con...The total number of atmospheric particle (AP) is an important datum for planetary science and geoscience. Estimating entire AP number is also a familiar question in general physics. With standard atmosphere model, considering the number difference of AP caused by rough and uneven in the earth surface below, the sum of dry clean atmosphere particle is . So the whole number of AP including water vapor is . The rough estimation for the total number of AP on other planets (or satellites) in condensed state is also discussed on the base of it.展开更多
In the daytime,building facades and ground surfaces are heated by solar radiation,and the resulting buoyancy can change the flow field inside street canyons.In this study,the impacts of uneven and time-varying heating...In the daytime,building facades and ground surfaces are heated by solar radiation,and the resulting buoyancy can change the flow field inside street canyons.In this study,the impacts of uneven and time-varying heating of surfaces inside an ideal urban street canyon(aspect ratio=1)on single-sided indoor natural ventilation are analyzed.This work introduces a methodology for a numerical approach based on the coupling between a computational fluid dynamics(CFD)model and an energy balance model.First,EnergyPlus is employed to calculate the time-varying and uneven surface heating.Simulations are performed at four typical study times(05:00,09:00,15:00,20:00)during a hot summer day(July 15)in Wuhan,China.Second,the surface temperature results are transferred to OpenFOAM for CFD simulation.Two inlet wind velocities(U_(ref))are investigated.The results show that for a relatively strong ambient wind(U_(ref)=3 m/s),the buoyancy caused by surface heating does not significantly change the airflow structures and indoor ventilation compared with those in the isothermal case.However,for a weak ambient wind(U_(ref)=0.5 m/s),the airflow structures inside the street canyon vary with the time of day.Moreover,the average air exchange rate(ACH)differs by-25.0% to 15.9%compared with that in the isothermal case,and the ACH of a single room increases by up to 2710%.The results indicate that the surface-heating-induced buoyancy is nonnegligible and should be carefully investigated,especially for weak ambient winds.展开更多
基金supported by the National Basic Research Program of China (Grant No.2010CB951701-2)the National Natural Science Foundation of China (Grant Nos. 91025011, 41130961)the Pingliang Station of Lightning and Hail Research, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences
文摘Utilizing experimental data of the atmospheric surface layer in the Gobi Oasis of Jinta in a comparative study, we demonstrate that under the condition of unstable stratification, the normalization variances of temperature in the oasis and Gobi Desert meetφs （z∧）= φθ（Z/∧） =αθ（-Z/ ∧）-1/3 while normalization variances of both humidity and CO2 in the oasis meet φ（Z/∧）= αs （1 - βs z /∧）-1/3 ; the normalization variance of temperature in the oasis is large due to disturbance by advection, whereas variance of CO2 in the Gobi Desert has certain degree of deviation relative to Monin-Obukhov （M-O） scaling, and humidity variance completely deviates from variance M-O scaling. The above result indicates that under the condition of advection, hu-midity variance meets the relation δ2 sm=D2 δ2SA ＋ δ2SB and it is determined by relative magnitude of scalar variance of ad- midity variance meets the relation δsm = D2δsA ＋ δsB vection transport. Our study reveals that, if the scalar variance of humidity or CO2 transported by advection is much larger than local scalar variance, observation value of scalar variance will deviate from M-O scaling; when scalar variance of advection transport is close to or less than local scalar variance, the observation value of scalar variance approximately meets M-O scal- ing.
文摘The total number of atmospheric particle (AP) is an important datum for planetary science and geoscience. Estimating entire AP number is also a familiar question in general physics. With standard atmosphere model, considering the number difference of AP caused by rough and uneven in the earth surface below, the sum of dry clean atmosphere particle is . So the whole number of AP including water vapor is . The rough estimation for the total number of AP on other planets (or satellites) in condensed state is also discussed on the base of it.
基金supported by the National Natural Science Foundation of China(No.51778251).
文摘In the daytime,building facades and ground surfaces are heated by solar radiation,and the resulting buoyancy can change the flow field inside street canyons.In this study,the impacts of uneven and time-varying heating of surfaces inside an ideal urban street canyon(aspect ratio=1)on single-sided indoor natural ventilation are analyzed.This work introduces a methodology for a numerical approach based on the coupling between a computational fluid dynamics(CFD)model and an energy balance model.First,EnergyPlus is employed to calculate the time-varying and uneven surface heating.Simulations are performed at four typical study times(05:00,09:00,15:00,20:00)during a hot summer day(July 15)in Wuhan,China.Second,the surface temperature results are transferred to OpenFOAM for CFD simulation.Two inlet wind velocities(U_(ref))are investigated.The results show that for a relatively strong ambient wind(U_(ref)=3 m/s),the buoyancy caused by surface heating does not significantly change the airflow structures and indoor ventilation compared with those in the isothermal case.However,for a weak ambient wind(U_(ref)=0.5 m/s),the airflow structures inside the street canyon vary with the time of day.Moreover,the average air exchange rate(ACH)differs by-25.0% to 15.9%compared with that in the isothermal case,and the ACH of a single room increases by up to 2710%.The results indicate that the surface-heating-induced buoyancy is nonnegligible and should be carefully investigated,especially for weak ambient winds.
