Locally-induced nonlinear modes and multiple equilibria in planetary fluids

It is demonstrated that nonlinear Rossby modes, such as modons and IG eddies, can be excited in planetary fluids by a sufficiently strong forcing of potential vorticity. When a weak forcing is balanced with a weak dissipation, two (linear and nonlinear) equilibrium states can be produced, depending on the initial condition. When the fluid is inviscid, a sufficiently strong steady forcing may generate a sequence of propagating nonlinear eddies. A weak forcing, by contrast, only generates linear Rossby waves. The criterion which divides the high amplitude nonlinear state and the low amplitude linear state may be interpreted in terms of a ratio of a time necessary to force the eddy to a time for a fluid particle to circulate about the nonlinear eddy once.     

Inertial theory of the mean Hadley circulation under the condition of nonstatic equilibrium

1 Introduction The mean meridional circulation plays an important role in the transportation and balance of heat, momen- tum, vortex and vapor between different latitudes. According to the data analysis, there are three circula- tions from the equator to the polar area: the Hadley circulation, a heat-driven circulation which rises around the equator and sinks at a certain latitude; the subpolar circulation, another heat-driven circulation around the polar area; and the Ferrel circulation, an i…     

Multiple time scale evaluation of the energy balance during the maize growing season,and a new reason for energy imbalance

Energy imbalance is a common problem associated with the measurement of surface energy using the eddy covariance method. In the evaluation of the energy balance, people usually pay more attention to the statistical result that the effective energy (the sum of sensible and latent heat) is systematically lower than the available energy (the difference of net radiation and ground heat flux). However, little attention has been paid to the existence of the reversed situation when the effective energy is larger than the available energy or their contribution to the overall energy closure rate. In this paper, based on the analysis of the energy balance on multiple time scales across the maize growth season, we conclude that the non-synchronization of energy components is the main reason for the existence of the reversed case. By shifting the phase of the effective energy components half an hour ahead, the rates of energy closure over all time scales are improved and dramatically reduce the number of the half-hourly samples when the energy ratio exceeds 1 or is below 0.5. According to the characteristics of the energy distribution and transformation over multiple time scales, latent heat is always the main type of energy cost, and the residual of the energy balance increases with the growth of the maize plant surpassing the sensible heat for seventy days. It is suggested that the heat storage and photosynthetic energy play an important role in the energy balance during the growing period of maize. Supported by National Basic Research Program of China (Grant No.2007CB714402) and State Key Laboratory of Remote Sensing Science (Beijing Normal University)     

绿色建筑材料研究与应用综述及发展趋势

对目前几种常用绿色建筑材料在国内外的研究现状及应用状况进行简述,对其存在的问题进行总结与分析,探讨其潜在的负面影响,并对其在未来绿色建筑应用中的发展趋势进行展望,得出以下结论:未来绿色建筑材料的发展要注重多种材料的复合,充分发挥不同种材料各自的优势以弥补某种单一材料所存在的缺陷;注重材料的循环利用,避免由于材料替换所带来的二次污染;开发研制新材料、新技术以改善现有材料在绿色建筑应用中的缺陷和不足。