排序方式: 共有32条查询结果,搜索用时 15 毫秒
21.
G.A. McBean 《大气与海洋》2013,51(4):254-267
Two different approaches to scaling turbulence in the planetary boundary layer over Lake Ontario are investigated. The height up to the inversion was found to be the appropriate scaling height while u. for near‐neutral and w* for unstable conditions were the appropriate scaling velocities. The results were in general agreement with the numerical models of Deardorff (1972) and Wyngaard, Cote, and Rao (1974). 相似文献
22.
23.
Gordon B. Murray Edward A. McBean Jonathan F. Sykes 《Ground Water Monitoring & Remediation》1995,15(4):148-154
Leakage rate calculations for both low- permeability soil liners and composite liners using flexible membrane liners (FMLs) overlying low-permeability soil are developed. Latin-Hypercube simulations with uncertainly assigned to the soil liner hydraulic conductivity value and the spatial frequency of FML holes are used to examine the variability in the liner leakage rates. The low-permeability soil hydraulic conductivity is the parameter with the greatest effect on landfill liner leakages rates. Composite liners have a significant impact on reducing leakage rates through the landfill liner. 相似文献
24.
The variations of the statistics of wind,temperature and humidity fluctuations with stability 总被引:1,自引:0,他引:1
G. A. McBean 《Boundary-Layer Meteorology》1971,1(4):438-457
Measurements of the turbulent fluctuations of wind, temperature and humidity were made in the atmospheric surface layer. The statistics of the fluctuations were investigated in both the time and frequency domains. The vertical wind, temperature and smaller-scale horizontal wind fluctuations appear to obey the Monin-Obukhov similarity hypothesis. The humidity fluctuations were found to be governed by a humidity flux stability parameter rather than the normal Monin-Obukhov length. 相似文献
25.
High frequency measurements of wind velocity and temperature were made during the Ocean Storms Project in November 1987. The dissipation method was applied to the resulting time series in order to determine friction velocities,u
*, and the characteristic temperature scale,t
*, at 1-min intervals. These values were then compared to the 1-min mean wind speed and air-sea temperature differences to determine relationships for the drag coefficient (C
d
) and Stanton number (C
h
). The drag coefficient was comparable to other values reported in the literature, although the variation with wind speed was greater than reported by other investigators. An examination of the residual time series indicated a systematic low frequency periodicity of about 2-hr duration which was attributed to a fluctuating wind interacting with the surface gravity wave field. The temperature fluctuations did not produce meaningful estimates ofC
h
for stable conditions. For unstable conditions, a value of 1.09±0.02×10–3 was found. 相似文献
26.
While the tortuosity coefficient is commonly estimated using an expression based on total porosity, this relationship is demonstrated to not be applicable (and thus is often misapplied) over a broad range of soil textures. The fundamental basis for a correlation between the apparent diffusion tortuosity coefficient and hydraulic conductivity is demonstrated, although such a relationship is not typically considered. An empirical regression for estimating the tortuosity coefficient based on hydraulic conductivity for saturated, unconsolidated soil is derived based on results from 14 previously reported diffusion experiments performed with a broad range of soil textures. Analyses of these experimental results confirm that total porosity is a poor predictor for the tortuosity coefficient over a large range of soil textures. The apparent diffusion tortuosity coefficient is more reliably estimated based on hydraulic conductivity. 相似文献
27.
While evapotranspiration (ET) is normally measured as one hydrologic component, evaporation (E), and transpiration (T) result from different physical-biological processes. Using a two-source model, a trapezoid framework has been widely applied in recent years. The key to applying the trapezoid framework model is the determination of the dry/wet boundaries of the land surface temperature-fractional vegetation coverage trapezoid (LST-fc). Although algorithms have been developed to characterize the two boundaries, there remains a significant uncertainty near the wet boundary which scatters in a discrete and uneven manner. It is therefore difficult to precisely locate the wet boundary. To address this problem, a Wet Boundary Algorithm (WBA) was developed in this study with the algorithm applied in the region of Huang-Huai-Hai plain of China, using the Pixel Component Arranging and Comparing Algorithm (PCACA) to retrieve ET from MODerate-resolution Imaging Spectroradiometer (MODIS) Data. The eddy covariance (EC) measurements from Yucheng station was used to verify the modified model where the root mean square error (RMSE) of 17.8 W/m2, Bias of −7.2 W/m2 for latent heat flux (LE) simulation in 28 cloudless test days. The ratio of transpiration to evapotranspiration (T/ET) varied between 0.48 and 0.81 over the Huang-Huai-Hai plain. The spatial and temporal distribution of ET revealed that agriculture practices have a significant influence on the hydrological cycle, where crop growth promotes the magnitude of ET. Likewise, harvesting activities significantly reduce ET. The proposed WBA algorithm significantly reduces the uncertainty of the trapezoid ET model caused by wet edge positioning. The analysis of the impact of agricultural activities on ET provide a better understanding how human activities change the hydrological cycle at regional scales. 相似文献
28.
The principal variability patterns (EOF) of the anomalies of total heat transfer from ocean to atmosphere computed from 30
years' monthly averaged data over the North Pacific Ocean (20°–60°N) showed variability was dominated by two patterns: a bipolar
pattern and a dominantly positive or negative pattern depending on the sign of the time series coefficients. The atmosphere
contributes greatly to the marine heating anomalies in most of the North Pacific in all seasons. In winter, a positive feedback
is formed between the Aleutian Low and the marine heating anomalies; in summer, the marine heating anomalies are controlled
by the heating on the Qinghai-Tibetan Plateau. Both patterns have a winter correlation with the Southern Oscillation Index.
Contribution No. 1534 from the Institute of Oceanology, Academia Sinica 相似文献
29.
Humidity fluctuations over land were measured by a Ly- humidiometer and dew point hygrometer; the results showed excellent agreement. From simultaneous measurements of vertical velocity, temperature, and downwind velocity, the universal shape of the spectra and cospectra for humidity transport were examined, and compared with those for heat and momentum. 相似文献
30.
G. A. McBean 《Boundary-Layer Meteorology》1982,23(2):185-196
Microscale temperature fluctuations were measured at 2 m above a grassy surface. The temperature-derivative spectrum was in general agreement with earlier results but the bump at nondimensional wavenumbers higher than 0.02 was not as pronounced as has been observed. The Obukhov-Corrsin constant for the one-dimensional temperature spectrum was evaluated to be 0.92 ± 0.05, consistent with recent results. The effects of instability and the vertical variation of temperature variance and kinetic energy dissipation are postulated to explain some of the difference with other spectra. 相似文献