Ensemble Forecast for Tropical Cyclone Based on CNOP-P Method: A Case Study of WRF Model and Two Typhoons

In this paper, we set out to study the ensemble forecast for tropical cyclones. The case study is based on the Conditional Nonlinear Optimal Perturbation related to Parameter (CNOP-P) method and the WRF model to improve the prediction accuracy for track and intensity, and two different typhoons are selected as cases for analysis. We first select perturbed parameters in the YSU and WSM6 schemes, and then solve CNOP-Ps with simulated annealing algorithm for single parameters as well as the combination of multiple parameters. Finally, perturbations are imposed on default parameter values to generate the ensemble members. The whole proposed procedures are referred to as the Perturbed Parameter Ensemble (PPE). We also conduct two experiments, which are control forecast and ensemble forecast, termed Ctrl and perturbed-physics ensemble (PPhyE) respectively, to demonstrate the performance for contrast. In the article, we compare the effects of three experiments on tropical cyclones in aspects of track and intensity, respectively. For track, the prediction errors of PPE are smaller. The ensemble mean of PPE filters the unpredictable situation and retains the reasonably predictable components of the ensemble members. As for intensity, ensemble mean values of the central minimum sea-level pressure and the central maximum wind speed are closer to CMA data during most of the simulation time. The predicted values of the PPE ensemble members included the intensity of CMA data when the typhoon made landfall. The PPE also shows uncertainty in the forecast. Moreover, we also analyze the track and intensity from physical variable fields of PPE. Experiment results show PPE outperforms the other two benchmarks in track and intensity prediction.     

基于人工湿地的水环境治理和优化技术在太湖流域的应用

水质优化技术在太湖流域水污染治理中起到了重要的作用。介绍了几类常用的基于人工湿地的水质优化技术,包括农村生活污水治理技术、城镇生活污水厂水质优化技术、河道治理技术及雨水治理技术。阐述了人工湿地在太湖流域水系统优化中的应用,包括阳澄湖莲花岛生态湿地对农村生活污水的治理和常熟新材料产业园生态湿地对工业尾水的治理,2个项目水处理效果良好,达到了相应的水质要求。探讨了基于人工湿地的水质优化技术在太湖流域水环境治理和优化的前景,该技术可在海绵城市建设、城镇污水处理厂提标、黑臭河道整治等领域推广和应用。