Nowcasting & Warning Operational System in the Middle Reaches of the Yangtze with Its Implementation

In order to meet the need for modern operational forecasting of severe storm events in the middle reaches of the Yangtze, MYNOS (Nowcasting & warning Operational System in the Middle reaches of theYangtze), an advanced and useful nowcasting system, is originally established in 2007 based on the experiences of the advanced nowcasting systems Auto-Nowcaster and WDSS-II of USA and GANDOLF of UK. MYNOS combines the resources of new generation radar network in China with the data from numerical weather prediction. Several advanced techniques and methods are developed and adopted as follows: Quality control of radar reflectivity field and the precipitation echo classification are achieved by identifying the structures of the vertical gradient and horizontal textures of radar reflectivity echoes. Real time formation technique of vertical reflectivity profile (VPR) is developed and used for vertical calibration of precipitation reflectivity factor. Important concepts of "quasi same-rain-volume sample" and "hourly equivalent reflectivity factor" are proposed, and the synchronously integrated method of radar and rain gauge (RASIM) is established. The cell gravity potential energy, as an important physical component of radar for describing the life span of storms, is proposed. The technique for automatic identification and tracking of severe weather is developed by means of radar derived parameters and the meso-scale output of physical parameters. The multi-scale characteristics of storm echoes through their life courses are analyzed and the echo filtering technique is studied, and the multi-scale precipitation nowcasting confined to the life time of each scale echo is realized. Potential forecasting products for severe convection meteorological phenomena (torrential rain, hail, thunderstorm, etc.) are developed based on numerical models and fuzzy logics. The problem of image registration and animation in ordinary GIS (Geographic Information System) is solved by introducing custom layer, and the nowcasting workstation equipped with the function of GIS along with numerical prediction, radar, satellite, lightning data and various quantitative monitoring, forecasting and warning products is developed from the bottom. MYNOS is put into operational experiments in May 2006 and has been in concentional operation since the flood season of 2007. The real-time generated output of MYNOS, such as valley quantitative precipitation estimation and nowcasting, strong convective weather classified potential diagnosis and identification warning products, provide an important foundation and reference for routine nowcasting operation.