ETKF-centralized case

Asynchronous observations collected in wildfire will bring errors when performing data assimilation. This method can extrapolate the asynchronous fire fronts to the same moment.在开展数据同化（data assimilation）工作时，野火现场采集的异步观测数据会引入误差。该方法可将异步获取的火锋（fire fronts）统一外推至同一时刻。