Satellite remote sensing of precipitation: progress and problems

Thirty years after satellite data were first used for assessing rainfall it is appropriate to critically review what has been achieved in this field to date, and what has not. Good progress has been made in developing and understanding the capabilities of satellite sensing systems, the physics of the atmosphere and land surfaces of the Earth, and in the development of computers capable of multiple, high-speed operations for near real-time data processing. However, all types of satellite monitoring of falling precipitation are subject to limitations, and progress is still relatively poor in several regards. To make matters worse, there has been a global trend towards the collection of less, not more, in situ data on precipitation over at least half of the last century. Foci for further research and operations are proposed. Some problems will require concentrated effort and significant expenditure if the recent rate of progress in this field is even to be maintained.