Design and Implementation of SWAN2.0 Platform

Severe Weather Automatic Nowcasting System 2.0(SWAN2.0) is a short-term nowcasting operational platform of CMA, providing nowcasting products and an early warning product generation tool. SWAN2.0 includes three types of meteorological products. Observation products, mainly composed of radar puzzles and automatic weather station(AWS) observations. Alarm products, including AWS elements alarms and radar echo alarms. Nowcasting products, providing 0-1 h radar echo forecast by COTREC movement vector and the tracking and forecasting of convection storm by SCIT (Storm Cell Identification and Tracking) or TITAN(Thunderstorm Identification, Tracking, Analysis and Nowcasting). SWAN2.0 is based on MICAPS4(Meteorological Information Comprehensive Analysis and Processing System Version 4) development framework, using C/S architecture. The server of SWAN2.0 is a scheduling platform of meteorological algorithm, which is deployed at the provincial meteorological administration, in charge of collecting data, running algorithm, and generating SWAN products. The client of SWAN2.0 is a complete working platform for weather forecasters deployed in national, provincial, and municipal meteorological observatories, which are used to display SWAN products, make analysis and produce weather forecast products. SWAN2.0 adopts new nowcasting technologies, such as three-dimensional variation assimilation retrieval of wind field, QPE(quantity precipitation estimation) by rain cluster, hail identification and meso-scale numerical model application, supporting weather forecasters to extend from traditional short-term weather forecasts and services to short-range and nowcasting forecasts of classified strong convective weather.SWAN2.0 integrates computer technology and forecasting technology to solve short-term forecasting problems. It uses the message queue to decouple business modules to enhance the flexibility and scalability of the platform, and can generate early warning produces automatically from alarm products. The hierarchical structure is adopted to optimize the design of the alarm module, and the alarm module efficiency is improved with pipeline filter model and asynchronous technology.In addition, SWAN2.0 adds two common data models, grid data model and feature data model, creating easy access to local products.In short, SWAN2.0 is not only a operational platform for forecaster but also a set of open data platform and development environment. It provides data services of real-time radar, automatic station and basic short-term nowcasting data, open operating environment and display terminal for the station, and provides support for station localization algorithm development.SWAN2.0 is released in July 2016, and popularized in nationwide. It provides an important foundation and reference for routine nowcasting operation.