数值模式的热带气旋强度预报订正及其集成应用

提供热带气旋强度预报产品的业务数值天气预报模式有很多,并已表现出一定的预报技巧,为提高对模式热带气旋强度预报产品的定量应用能力,分析2010—2012年7个业务数值模式的西北太平洋热带气旋强度预报,发现预报误差不仅受到模式热带气旋初始强度误差的显著影响,还与热带气旋及其所处环境的初始状况有密切关系,包括热带气旋初始强度、尺度、移速、环境气压、环境风切变、热带气旋发展潜势等。根据这些因子与各模式热带气旋强度预报误差之间的相关性,采用逐步回归方法建立热带气旋强度预报误差的统计预估模型,并通过逐个热带气旋滚动式建模来进行独立样本检验。检验结果表明,基于误差预估的模式订正预报比模式直接输出的热带气旋强度预报有显著改进,在此基础上建立的热带气旋强度多模式集成预报方案相对气候持续性预报方法在12 h有28%的正技巧,在24—72 h则稳定在15%—20%,具有业务参考价值。

A multi-model consensus forecast technique for tropical cyclone intensity based on model output calibration

Forecast errors of the tropical cyclone (TC) intensity in the western North Pacific region are analyzed for seven operational numerical weather prediction models during 2010-2012. It is found that the intensity forecast error is significantly related not only to initial error, but also to initial TC intensity, size, and translation speed. Other factors highly related to the forecast errors include the environment pressure, vertical wind shear and maximum potential intensity. The stepwise regression technique is applied to set up model forecast error estimation equations, which can be used to calibrate the model outputs. The independent experiments exhibit that the calibrated model forecasts have significant skill over the original model outputs. A multi-model consensus forecast technique for TC intensity is then developed based on the calibrated model outputs and it shows a 28% (15%-20%) skill at 12 h (24-72 h) over the climatology and persistency technique forecasts for TC intensity. Such a consensus technique is much more skillful than the consensus based on the original model outputs and has the potential to be applied in real time operation.