知识与财富的链接
电线积冰是电网正常运行中最大的气象灾害之一,而冻雨是造成电线积冰事故的主要灾害性天气。利用耦合了中尺度天气研究和预报(weather research and forecasting, WRF)模式的美国空军气象局(Air Force Weather Agency, AWFA)冻雨预报系统,对发生在中国南方的3次冻雨事件进行预报,通过威胁指数(threat scores,TS)评分对AWFA系统在中国地区的冻雨预报能力进行了评估,并根据其输出的冻雨参数,用覆冰增长模型对三次冻雨过程中,电线积冰厚度进行了模拟。结果表明:冻雨事件的发生必须同时满足逆温层、空中高液态含水量和地温低于0℃这三个气象条件;AFWA冻雨预报系统对中国冻雨也有一定的预报能力,但预测范围较实际观测的区域偏大,三次冻雨事件预报TS评分在0.30～0.63,平均为0.45;模拟电线积冰厚度的范围与观测的冻雨密集区相当吻合,对明显的冻雨过程有较好的预报能力且能够获得电线积冰厚度的精细化分布。研究结果对中国南方冻雨预报、电线积冰预报有重大的参考价值,并为电网的防灾减灾提供了坚实的理论支撑。
Abstract: The wire icing is the most serious meteorological disaster in the power system’s operation, and the freezing rain is the major disastrous weather causing the wire icing accidents. By using the AWFA freezing rain forecasting system coupled with the mesoscale model WRF, the present research conducted forecast on the three freezing rain episodes in Southern China. The forecasting ability of the AWFA system was examined by testing the TS scores of the simulation results. Based on the freezing rain parameters given by the AWFA system, the wire icing thickness was simulated by using the Ice Acceleration Forecast System, and the results are as follows: 1) A freezing rain episode must meet the criteria below at the same time: existence of a thermal inversion layer, high LWC, and ground temperature below 0°C. 2) The AFWA system is able to forecast freezing rain weather in China, but may overestimate the freezing rain area. The TS scores of the three freezing rain episodes are among 0.30 and 0.63, with an average of 0.45. 3) The simulated wire icing area matched well with the observed intensive freezing rain area, suggesting that the model has good forecasting ability to forecast the freezing rain progress, and is adequate to give out a fine spatial variation of the wire icing thickness. The present research has referenced value to the freezing rain prediction and wire icing forecast in Southern China, and provides valid theoretical foundation for the disaster prevention and reduction of the electric power system.
