1、Airborne Weather Radar(WXR)Airborne Weather Radar(WXR) Con2: Introduction to WXR Con2: Introduction to WXR电子信息与自动化学院Airborne Weather RadarOutlines For Con21 Aviation weather 1 Aviation weather 2 Introduction2 Introduction purpose purpose descriptiondescription displaydisplay3 Operating Modes3 Operat
2、ing Modes Weather Weather Map Map Turbulence Turbulence Predictive Predictive windshearwindshear4 Structure and Location 4 Structure and Location 5 Latest Evolutions5 Latest Evolutions2电子信息与自动化学院Airborne Weather RadarCon2-1 Con2-1 Aviation weather An airborne radars pulse energy is optimized to dete
3、ct water. The radiated radar energy reflects best when the bipolar (positive and negative) water molecules are able to align. When water freezes, the water molecules are locked into an ice crystal lattice and are unable to align to reflect radar energy efficiently. (example: microwave)Water (rain) i
4、s an excellent radar reflector.Dry snow and ice crystals are very poor reflectors of radar energy. Wet hail provides the strongest reflection of radar energy. Dry hail reflects some radar energy simply due to its size. Reflectivity characteristics 3电子信息与自动化学院Airborne Weather RadarCon2-1 Con2-1 Aviat
5、ion weather A thunderstorm is composed of three parts：The bottom portion of the storm, below the freezing level, is composed entirely of liquid precipitation (i.e., rain) and is the most reflective portion of the storm.The middle portion of a thunderstorm occurs above the freezing level (0oC) and up
6、 to the altitude where the outside air temperature drops below 40oC. This section of the storm is composed of a combination of ice crystals and supercooled water.The top of a thunderstorm is composed entirely of ice crystals and reflects very little radar energy. At temperatures less than 40oC, liqu
7、id water no longer exists and only ice crystals are present.Thunderstorm/rain4电子信息与自动化学院Airborne Weather RadarCon2-1 Con2-1 Aviation weather 湍流，也称为紊流，乱流，是指发生在一定空域中的急速且多变的运动气流。湍流区域中的不同位置，气流速度速度和方向方向的变化相当剧烈。湍流是根据区域中微粒的速度偏差速度偏差来定义的，它与微粒的绝对速度无关。湍流报警门限为5m/s(18km/h)Turbulence5电子信息与自动化学院Airborne Weather Ra
8、darCon2-1 Con2-1 Aviation weather Black represents zero to minimal reflectivity. Green represents light reflectivity. Yellow represents moderate reflectivity. Red represents heavy to extreme reflectivity. Magenta indicates turbulence.A normal thunderstorm is circular or oval in shape. Variations fro
9、m this normal shape are indicative of a shear condition within the thunderstorm and can serve as clues to hazardous weather.6电子信息与自动化学院Airborne Weather RadarCon2-1 Con2-1 Aviation weather v WX (weather) mode: The four colors displayed represent different WX (weather) mode: The four colors displayed
10、represent different storm intensities. storm intensities. v WX+T (Weather Plus Turbulence) Mode: It enables display of WX+T (Weather Plus Turbulence) Mode: It enables display of weather targets with turbulence informationweather targets with turbulence information7电子信息与自动化学院Airborne Weather RadarCon
11、2-1 Con2-1 Aviation weather v Wind shearWind shear is the meteorologists way of describing a rapid rapid changechange in either wind speedwind speed or wind directionwind direction over a short period of time or distance. v Windshear occurs in all directions, but for convenience, it is measured alon
12、g vertical and horizontal axis, thus becoming vertical and horizontal windshear.v The rapid change in wind speed and/or direction poses a very real threat to airplanes during take-off and landing.v Wind shear is caused by downburst. A downburstdownburst（下击暴下击暴流流） is a strong downdraft which causes d
13、amaging winds on or near the ground.v The term microburstmicroburst and marcoburstmarcoburst describe the size of the downburst(4km). Microburst is more important than marcoburst to aviation safety, it can cause damaging winds as high as 75 m/s(168 mph,270 km/h). v The key difference between downbur
14、st downburst and tornado tornado is in two words - ININ and OUTOUT8电子信息与自动化学院Airborne Weather RadarCon2-1 Con2-1 Aviation weather (a)低空风切变对飞机运行安全的影响示意图低空风切变对飞机运行安全的影响示意图(b) 雷暴引发的风切变雷暴引发的风切变9电子信息与自动化学院Airborne Weather RadarCon2-1 Con2-1 Aviation weather v Microbursts combine two distinct threats to a
15、viation safety: the downburst part, resulting in strong downdrafts; the outburst part, resulting in large horizontal windshear and wind component shift from headwind to tailwindHeadwind gust instantaneously increases the aircraft speed and thus tends to make the aircraft fly above intended path and/
16、or accelerate.A downdraft affects both the aircraft Angle-Of-Attack (AOA) and the aircraft path since it makes the aircraft sink.Tailwind gust instantaneously decreases the aircraft speed and thus tends to make the aircraft fly below intended path and/or decelerate.10电子信息与自动化学院Airborne Weather Radar
17、Con2-1 Con2-1 Aviation weather (a) Headwind zone(b) Power reduction(c) Indicated airspeed transition(d) Recovery or loss of flight11电子信息与自动化学院Airborne Weather RadarCon2-Con2-2 General descriptionv Purpose: the weather radar (WXR) system supplies these visual indications: weather conditions; windshea
18、r events; land contours.v Description: WXR operates on the same principle as an echo. The WXR system transmits radio frequency (RF) pulses in a 180 degree area forward of the airplane. Objects reflect the pulses back to the receiver. The receiver processes the return signal to show weather, terrain,
19、 and windshear events.v Display: The WXR returns show in four different colors on the navigation displays (ND). Colors of the indications give the crew information about the intensity of the returns.The predictive wind shear (PWS) cautions and warnings show in amber and red on the ND and PFD display
20、s. Also, there are aural alerts for PWS cautions and warnings.12电子信息与自动化学院Airborne Weather RadarCon2-Con2-2 General description13电子信息与自动化学院Airborne Weather Radar14电子信息与自动化学院Airborne Weather RadarCon2-Con2-2 General descriptionWXR provides the flight crew with a representation of weather WXR provides
21、 the flight crew with a representation of weather (compensated for A/C attitudes):(compensated for A/C attitudes): - Localisation (tilt and distance) and density of water particules - Localisation (tilt and distance) and density of water particules - Turbulence information and windshear detection th
22、rough particle - Turbulence information and windshear detection through particle horizontal speed detectionhorizontal speed detectionWXR-Airborne weather radar15电子信息与自动化学院Airborne Weather RadarCon2-Con2-2 General descriptionTwo Suppliers:1. Honeywell (RDR-4B/4000)2. Rockwell Collins (WXR-2100)16电子信息
23、与自动化学院Airborne Weather RadarCon2-2Con2-2 General description1NM=1852m1mile=1609m17电子信息与自动化学院Airborne Weather RadarCon2-2 Con2-2 General descriptionR 1 mm/h, Z1 20 dBz: black dBz: 10 log ZR 1 to 4 mm/h, Z2 30 dBz: green Z: reflectivity of the rainR 4 to 12 mm/h, Z3 12 mm/h, Z4 40 dBz: red R expressed
24、 in mm/h4级编码方案，Z为反射系数，R为降雨量18反射率(mm/h)颜色显示无雨区50.8回波强度回波强度 降雨量降雨量大小大小大小电子信息与自动化学院Airborne Weather RadarCon2-Con2-3 Operating Modes(WX, WX+T)19电子信息与自动化学院Airborne Weather RadarCon2-Con2-2 General description20 Accurate Weather that affects the aircraft flight path from the nose of the aircraft to 320 N
25、M 40 NM40 NM100 NM100 NMGround Clutter Free300 NM300 NM 1st Generation Hazard Analysis based on region and time of year Attenuation Alert Certified Turbulence to 40 NMAttenuation Alert40 NM Turbulence OverFlightTM ProtectionOverFlight Protection200 NM200 NM Predictive Windshear Ground Clutter Free D
26、isplay电子信息与自动化学院Airborne Weather RadarCon2-Con2-3 Operating Modesknot(节节)=1 NM/h（PWS）AGL: Above Ground Level1mile=5280feet1feet=30.48cm21电子信息与自动化学院Airborne Weather RadarCon2-Con2-3 Operating Modes22电子信息与自动化学院Airborne Weather RadarCon2-Con2-3 Operating ModesvPredictive Windshear (HMI)Predictive Winds
27、hear (HMI)23电子信息与自动化学院Airborne Weather RadarCon2-Con2-3 Operating Modes24电子信息与自动化学院Airborne Weather RadarCon2-Con2-3 Operating ModesWXR Control panel of 737NG 25电子信息与自动化学院Airborne Weather RadarCon2-Con2-3 Operating Modes26通过控制板鉴别飞机安装的Multiscan雷达系统（Boeing）电子信息与自动化学院Airborne Weather RadarCon2-Con2-3 O
28、perating Modes27通过控制板鉴别飞机安装的Multiscan雷达系统（Airbus）电子信息与自动化学院Airborne Weather RadarCon2-Con2-3 Operating Modes28电子信息与自动化学院Airborne Weather RadarCon2-Con2-4 Structure and Location Structure and Location 29电子信息与自动化学院Airborne Weather RadarCon2-Con2-4 Structure and Location Structure and Location 30电子信息与自
29、动化学院Airborne Weather RadarCon2-Con2-4 Structure and Location Structure and Location 31电子信息与自动化学院Airborne Weather RadarCon2-Con2-4 Structure and Location Structure and Location 32电子信息与自动化学院Airborne Weather RadarCon2-Con2-5 Latest Evolutions33电子信息与自动化学院Airborne Weather RadarCon2-Con2-5 Latest Evolutions34电子信息与自动化学院Airborne Weather RadarCon2-Con2-5 Latest Evolutions35
