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Terminal Doppler Weather Radar (TDWR) is a Doppler weather radar system with a three-dimensional "pencil beam" used primarily for the detection of hazardous wind shear conditions, precipitation, and winds aloft on and near major airports situated in climates with great exposure to thunderstorms in the United States.〔(【引用サイトリンク】title=Terminal Doppler Weather Radar Information )〕 As of 2011, all were in-service with 45 operational radars, some covering multiple airports in major metropolitan locations, across the United States & Puerto Rico.〔(【引用サイトリンク】title=Search Proximity to Terminal Doppler Weather Radars (TDWRs) )〕〔(【引用サイトリンク】title=TDWR Locations and Frequencies )〕 Several similar weather radars have also been sold to other countries such as China (Hong Kong).〔 Funded by the United States Federal Aviation Administration (FAA), TDWR was developed in the early 1990s at Lincoln Laboratory, part of the Massachusetts Institute of Technology, to assist air traffic controllers by providing real-time wind shear detection and high-resolution precipitation data.〔(【引用サイトリンク】title=Terminal Doppler Weather Radar (TDWR) )〕 The primary advantage of TDWR over previous weather radars is that it has a finer range resolution—meaning it can see smaller areas of the atmosphere.〔 The reason for the resolution is that the TDWR has a narrower beam than traditional radar systems, and that it uses a set of algorithms to reduce ground clutter.〔 == Characteristics == TDWR uses the frequency between 5600-5650 MHz (5 cm wavelength) carrier wave, with an angular resolution beam of 0.55 degrees. In reflectivity, the resolution in distance is within of the radar and from to to the radar.〔 The reason for this difference is that the width resolution being angular, at larger range the width of the beam becomes quite large and to obtain a better averaging of data in a resolution volume, one has to increase the number of range pulse bins. This cut off is arbitrarily set for the software at . In radial velocities, data are available up to from the radar with the full angular resolution of 0.5 degrees and range resolution of .〔 Because of the Pulse Repetition Frequency (PRF) used, there is aliasing and the maximum non-ambiguous velocity is .〔 TDWR can perform near-surface scans at a 0.1-0.3 degree angle of inclination from the Earth's surface every minute. It can also perform composite scans in which the radar observes at several different angles of inclination in order to obtain a fuller picture of the atmospheric conditions; each such composite scan requires 6 minutes.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Terminal Doppler Weather Radar」の詳細全文を読む スポンサード リンク
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