TABLE OF CONTENTS It is clear from the discussion hitherto in this book that the primary sensor of the modern aviation weather surveillance system is the Doppler weather radar in its different forms. It not only estimates the various reflectivity-derived parameters such as the intensities of rainfall and hailfall, but also detects and provides qualitative and quantitative pictures of wind velocity and turbulence fields in the atmosphere. Modern aviation weather surveillance systems, by virtue of their ability to measure these parameters, and automatically derive higher-level weather products and perform their interpretation from the aviation management point of view, represent a quantum jump over the state of the art existing till recently. Yet there is scope for further improvement, and some courses of action for effecting these are visible and being pursued already. One of the major directions of possible improvement is the development and deployment of polarisation diversity radars.
[1]This chapter has been contributed by Dr. Dusan S. Zrnic' of the National Severe Storms Laboratory, Norman, OK, USA
Conventional weather radars, as well as the modern Doppler weather radars being deployed for advanced aviation weather surveillance, have the common characteristic that they employ a uniform polarisation for all signals radiated by them. The reception of the reflected signal is also most often at a common polarisation, usually the same as that of the transmitted signal. The difference in the polarisation characteristics of different scatterers is sometimes used to detect them more optimally, as for example in the...
