Terminal Weather System with Fast-Scanning Phased Array Weather Radar in Japan

Airport operation demands higher resolution of weather radar information than general use of weather system. A horizontal profile of precipitation echo with high spatial resolution of tens of meters enables to accurately classify hazardous phenomena such as a microburst and a gust front. High temporal resolution less than 1 min achieves to detect them in their early stages, and to offer a short-term (10- to 30-minute) prediction. Further, such high resolution weather radar information can enhance the following products of lightning, and icing cloud, integrating other co-located sensors in an airport. In airport operation, it is important not only to understand current situation of such weather information but also to predict a short-term (10- to 30-minute) situation of them since, for example, decision of landing needs to be made 10- to 30-minute before the landing. Japan Aerospace Exploration Agency has started a research project, Aircraft safety management system. In the research project, we are pursuing feasibility studies to develop a new terminal weather system based on the Phased Array Weather Radar (PAWR) with fast-scanning capability, which has been newly developed by Osaka University and Toshiba Corporation on funding of National Institute of Communication Technology (NICT). Overview of the terminal weather system and general operation image of the PAWR are shown in Figures 1 and 2, respectively. The PAWR applies a digital beam forming technique to observe several directions simultaneously, which accomplishes several times faster volume scanning than formal weather radars. An upper hemisphere of 60-km radius around an airport equipping the PAWR is covered with 90 elevation (every 1 deg from 0 to 90 deg) and 300 azimuth (every 1.2 deg from 0 to 360 deg) angles within a short time of 30 sec due to this technique. We currently plan three main topics; (1) high accuracy lightning information, with co-locating lightning sensors and aircraft data of high resolution vertical distribution of temperature downlinked via Secondary Surveillance Radar (SSR) mode S system, (2) high accuracy icing cloud information, with dual-polarization measurements of the PAWR and the the aircraft temperature data, and (3) short-term (10- to 30-minute) prediction based on 30-sec high temporal resolution radar data and wind data of scanning lidar. In this presentation, overview and progress of this research project will be described.