3机载气象雷达 - 气象雷达概述.ppt

Airborne Weather Radar(WXR) Con2: Introduction to WXR
Outlines For Con2
1 Aviation weather
Rain(precipitation)
Turbulence
Wind shear
2 General description for WXR
3 Operating Modes
4 Structure and Location
2
Con2-1 Aviation weather--rain
An airborne radar’s pulse energy is optimized to detect 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) is 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
Con2-1 Aviation weather--rain
A thunderstorm posed of three parts:
The bottom portion of the storm, below the freezing level, posed entirely of liquid precipitation (., rain) and is the most reflective portion of the storm.
The middle portion of a thunderstorm occurs above the freezing level (0oC) and up to the altitude where the outside air temperature drops below – 40oC. This section of the storm posed of bination of ice crystals and supercooled water.
The top of a thunderstorm posed entirely of ice crystals and reflects very little radar energy. At temperatures less than – 40oC, liquid water no longer exists and only ice crystals are present.
Thunderstorm/rain
4
Con2-1 Aviation weather--turbulence
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,气流速度和方向的变化相当剧烈。
湍流是根据区域中微粒的速度偏差来定义的,它与微粒的绝对速度无关。
湍流报警门限为5m/s
Turbulence
5
Con2-1 Aviation weather--turbulence
• 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. Va