Optical properties of selected plants from a tropical mountain ecosystem - Traits for plant functional types to parametrize a land surface model

The optical properties (reflectance and transmittance) of selected leaves from a tropical mountain rainforest in southern Ecuador are determined to parametrize optical traits of plant functional types (PFT) of a state of the art land model (Community Land Model, CLM). 46 spatially dominating species are selected from 4 different forest types, the subpáramo and a succession stage of pasture areas representing ecologically predefined functional types within the study area. Measurements are conducted under a standardized experimental setup with a field spectrometer covering the radiation between 305 and 1305 nm. The results of the optical properties of all species are checked for similarity by cluster analysis and are compared to the composition of species of the predefined PFTs. Furthermore the results are compared to other studies, the default values for the globally defined PFT of tropical evergreen trees in the CLM and another forest growth model operated in the same study area. The results show that the clusters aggregated by the reflectance, transmittance or combined properties do not represent the predefined PFTs. The values of the other studies suggest a reassessment of the experimental setup for the transmittance measurements. Nevertheless, new reflectance values for the regionalized PFTs can be determined. The optical values differ from the CLM-PFT of tropical evergreen trees, and new values for the reflectance are recommended.     

氙灯/TiO2体系下敌草隆光催化降解动力学的研究

利用光催化技术通过单因素和中心复合实验对敌草隆的降解动力学进行了研究.在单因素实验中,通过Langmuir-Hinshelwood动力学模型对敌草隆的光催化降解进行了模拟,并系统地考察了催化剂用量、溶液初始pH值和温度对其降解动力学的影响,结果表明,敌草隆的光催化降解符合假一级动力学,中性条件有利于敌草隆的光催化降解,并且随着温度的升高敌草隆光催化降解速率增大;而中心复合实验则着重探讨3个单变量之间相互作用的关系,通过建立数学模型得到敌草隆光催化降解的最佳条件为:TiO2浓度2.98 g·L-1,溶液初始pH=7.78,反应温度为40℃.     

A global Bayesian sensitivity analysis of the 1d SimSphere soil–vegetation–atmospheric transfer (SVAT) model using Gaussian model emulation

Sensitivity analysis consists of an integral and important validatory check of a computer simulation model before the code is used in performing any kind of analysis operation. The present paper demonstrates the use of a relatively new method and tool for conducting global sensitivity analysis (GSA) for environmental models, providing simultaneously the first GSA study of the widely used 1d soil–vegetation–atmospheric transfer (SVAT) model named SimSphere. A software platform called the Gaussian emulation machine for sensitivity analysis (GEM SA), which has been developed for performing a GSA via Bayesian theory, is applied to SimSphere model in order to identify the most responsive model inputs to the simulation of key model outputs, detect their interactions and derive absolute sensitivity measures concerning the model structure. This study is also very timely in that, use of this particular SVAT model is currently being considered to be used in a scheme being developed for the operational retrieval of the soil surface moisture content by National Polar-orbiting Operational Environmental Satellite System (NPOESS), in a series of satellite platforms that are due to be launched in the next 12 years starting from 2016.The employed GSA method was found capable of identifying the most responsive SimSphere inputs and also of capturing their key interactions for each of the simulated target quantities on which the GSA was conducted. The most sensitive model inputs were the topography parameters (slope, aspect) as well as the fractional vegetation cover and soil surface moisture availability. The implications of these findings for the future use of SimSphere are discussed.     

Application of a three-dimensional model for assessing effects of small clear-cuttings on radiation and soil temperature

A three-dimensional model Mixfor-3D of soil–vegetation–atmosphere transfer (SVAT) was developed and applied to estimate possible effects of tree clear-cutting on radiation and soil temperature regimes of a forest ecosystem. The Mixfor-3D model consists of several closely coupled 3D sub-models describing: forest stand structure; radiative transfer in a forest canopy; turbulent transfer of sensible heat, H₂O and CO₂ between ground surface and the atmospheric surface layer; evapotranspiration of ground surface vegetation and soil; heat and moisture transfer in soil. The model operates with the horizontal grid resolution, 2 m × 2 m; vertical resolution, 1 m and primary time step, 1 h.