Development of microwave technologies and our ability to observe Tropical Cyclones (TCs) from within by instrumented aircraft penetrations and from space via satellites has contributed much of the knowledge and understanding of TC's that exist today. We can follow the structure and development of a TC life cycle from formation (genesis) through the mature stage as a dangerous typhoon, hurricane or cyclone, as they are variously called around the globe, through to extratropical transition and dissipation, including Rapid Intensification (RI) and Rapid Decay (RD) episodes. The data from satellite microwave radiometers, scatterometers, altimeters, Synthetic Aperture Radars (SARs), microwave sounders, a rain radar and a cloud profiling radar as well as coastal radars, airborne radars and microwave radiometers have all contributed to changing the fields of TC research and operational forecasting. Here we highlight some crucial steps towards current capabilities and describe a short history of these developments and current value of the technology to TC research, numerical prediction and operational warnings. We outline the development of a Stepped-Frequency Microwave Radiometer (SFMR) which measures surface wind and rain rate remotely along a line from within a storm (AFRC WC-130J, NOAA WP-3D and G-IV). We show the amazing small-scale details of TC structure revealed by SAR's, which have the highest resolution of all satellite microwave instruments. The 30-year development of satellite scatterometry for obtaining surface wind vectors and the multi-faceted evolution of microwave radiometry along with the associated imagers and sounders are reviewed. The use of altimetry to reveal the hidden heat content in subsurface eddies in the ocean, which provide fuel for intensification of TCs, is discussed. The first spaceborne weather radar on the Tropical Rainfall Measuring Mission (Precipitation Radar or PR)is shown to greatly enhance knowledge of TC structure and rainfall forecasting through its large observational data base of the world's TCs.

This review provides representative examples rather than a complete historical review of each microwave component. It concludes with a description of some promising ideas for future advances, such as dual frequency scatterometers, scanning altimeters, multi-frequency, dual polarization scanning SFMRs (called Hurricane Imaging RADiometers or HIRADs) and a constellations of microwave radiometers with a rain radar used for inter-calibration between sensors in the Global Precipitation Measuring (GPM) Mission.