Square Of Wind Speed Research Articles

Plant Feedback Aggravates Soil Organic Carbon Loss Associated With Wind Erosion in Northwest China

AbstractSoil organic carbon (SOC) loss caused by wind erosion can profoundly impact carbon (C) balance in arid and semiarid regions. Nevertheless, previous researches mainly focused on the direct effect of wind erosion through removing surface soil only but ignored its indirect effects associated with soil nitrogen (N) loss and subsequent reductions of plant productivity. To better understand the wind erosion effect on SOC storage, we conducted a large‐scale field experiment by manipulating wind erosion at 371 sites in arid and semiarid regions of northwest China from 2014 to 2016. We further integrated an observation‐based empirical equation of wind erosion process into a terrestrial biogeochemical model to evaluate the direct and indirect effects of wind erosion on SOC storage in northwest China. The observed results showed that direct SOC losses increased linearly with the square of wind speed but decreased nonlinearly with soil water content. Over the 34 years (1980–2013), simulated cumulative SOC losses associated with wind erosion in northwest China were 27.47 Tg C, among which the indirect effects contributed to 2.68 Tg C (9.76%). The indirect effect of wind erosion initially enhanced SOC storage by decreasing heterotrophic respiration from 1984 to 1988 but decreased SOC pool by reducing net primary productivity due to soil N loss under the long‐term wind erosion scenario. This work, for the first time, quantified the indirect impact of wind erosion on SOC storage via feedback of suppressed plant productivity, which is crucial for the convincing assessment on SOC storage in arid and semiarid regions.

Fatigue Analysis of Greenhouse Structure under Wind Load and Self-Weight

The design strength of a greenhouse structure is generally determined by analyzing strength after applying wind load using the wind pressure coefficient according to a design guide. Until now, the stability analysis for wind load has been performed through static structural analysis. However, a greenhouse is subjected to dynamic wind loads of various amplitudes, and it is reasonable to judge stability through fatigue analysis. For fatigue analysis, a stress-normalized model was constructed based on the square of wind speed, and the value obtained by squaring wind speed was used as dynamic load time data. Life cycle was calculated under stress generated by self-weight by compensating fatigue estimation stress. Furthermore, the effect of self-weight was examined and errors of up to 21% were obtained depending on the configuration of the stress-normalized model. When self-weight and wind speed were applied simultaneously, the effect of self-weight reduced when the stress-normalized model was used at high wind speed. Therefore, it is appropriate that the fatigue analysis is based on the fatigue stress model normalized by the square of wind speed, fatigue estimation stress is corrected to the static stress due to self-weight, and the square of wind speed is used as the dynamic load.

Repair Wind Field of Oil Spill Regional Using SAR Data

In this paper, we compared the normalized radar cross section (NRCS) of the synthetic aperture radar in the cases of oil spill and clean sea areas with image samples and determined their thresholds of the NRCS of SAR. we used the NRCS of clean water from the adjacent patches spill area to replace NRCS of oil spill area and retrieval wind field by CMOD5.N and comparison of wind velocity mending of oil spill with Model data the root mean square of wind speed and wind direction inversion are 0.89m/s and 20.26°satisfactory results, respectively. Therefore, after the occurrence not large scale oil spill, the real wind field could be restored by this method.

A Practical bi-parameter formula of gas transfer velocity depending on wave states

The parameter that describes the kinetics of the air-sea exchange of a poorly soluble gas is the gas transfer velocity which is often parameterized as a function of wind speed. Both theoretical and experimental studies suggest that wind waves and their breaking can significantly enhance the gas exchange at the air-sea interface. A relationship between gas transfer velocity and a turbulent Reynolds number related to wind waves and their breaking is proposed based on field observations and drag coefficient formulation. The proposed relationship can be further simplified as a function of the product of wind speed and significant wave height. It is shown that this bi-parameter formula agrees quantitatively with the wind speed based parameterizations under certain wave age conditions. The new gas transfer velocity attains its maximum under fully developed wave fields, in which it is roughly dependent on the square of wind speed. This study provides a practical approach to quantitatively determine the effect of waves on the estimation of air-sea gas fluxes with routine observational data.

Turbulent fluxes over inhomogeneous landscape

Mesoscale surface turbulent fluxes over a complex terrain surrounded by oceans have been investigated using a 3-D numerical mesoscale model, under conditions with and without synoptic flows. The study indicated that under synoptically calm condition, the allocation and intensity of mesoscale surface turbulent fluxes (MSTFs) were greatly impacted by the thermally forced mesoscale circulation (TFMC) over mesoscale heterogeneous landscape. The maximum values of sensible (Hs) and latent (LE) heat fluxes were located over the convergent zones and considerably impacted by the soil wetness (M), but did not depend strongly on the atmospheric background thermal stability (β0). The simulated results suggested that the sensible heat flux was closely proportional to the square of wind speed in the surface layer. By the action of synoptic flow, the allocation of LE was shifted to downwind, its intensity increased.

Surface radon measurements in the North Pacific Ocean station Papa

Eleven surface radon profiles were measured at windy winter station Papa in the North Pacific Ocean during January–February 1972. A steady state two-layer vertical mixing model is proposed to explain the vertical distribution of radon. The vertical eddy diffusivity within the mixed layer at the Papa site was thus estimated to be about 200 cm2/s. The mean radon transfer velocity is estimated to be 3.6 m/d. The corresponding magnitude of the thickness of stagnant boundary film is 20 μ. Comparison of this exchange with that obtained previously in the trade wind dominated Bomex area appears to support the results of Kanwisher's (1963) laboratory experiments that show the rate of gas exchange across the air-water interface to be proportional to the square of wind speed.

膨脹式救命筏の漂流速度についての実験的研究

This paper relates to some experiments with respect to the drifting speed of inflatable type life raft under the wind. Tests were carried out for model in the wind-tunnel with water tank and for actual raft at sea. Raft is used and that principal dimension and experimental conditions are shown in table 1. Hydrodynamic and and aerodynamic forces are measured in model test and the drifting speeds are observed in model and actual experiments. The tests results are as follows ; 1) The aerodynamic force increases with the square of wind speed linearly and the coefficients of the forces are shown in fig.1. 2) The hydrodynamic force increases with the square of drifting speed and the coefficients of the forces are shown in fig.2. 3) The drifting speed caluculated with the balancing of the aero and hydrodynamic forces is good agreement with the speed obtained by the drifting experiments of actual raft at sea. 4) The effect of sea anchor against the drifting of raft is not so expectable in practise as shown in fig.4.

Properties of spectra of atmospheric turbulence at 100 metres

AbstractThe properties of spectra of vertical and horizontal turbulence and of their cross‐spectra, at elevations near 100m, are summarized; a few spectra from lower levels are considered. The following tentative conclusions are drawn: At frequencies of the order of 100c/hr and above, the spectral intensity is proportional to the square of the mean wind speed and essentially independent of the radiation intensity. At lower frequencies, the ratio of spectral intensity to the square of the wind speed increases with increasing incoming radiation. The intensity‐ratio of the co‐spectrum of vertical and horizontal velocity to the spectrum of vertical velocity increases with increasing wind shear. It also decreases with increasing frequency, n, approximately as n−1. At low frequencies, the spectral intensity of the horizontal velocity components is generally much large than that of the vertical velocity. At high frequencies, the spectral intensities of all velocity components are of the same order of magnitude. At low frequencies, the ratio of vertical to horizontal spectral density increases with increasing radiation. The quadrature spectra at a given frequency tend to be negative with large radiation, positive with little radiation. This indicates that edies are low and wide with little radiation, and tall with much radiation. The frequency at the maximum of the vertical velocity spectrum decreases with increasing height and increasing radiation intensity. The ratio of tubulent to mean energy is somewhat larger for air with over‐land trajectories than for air with oceanic trajectories.