Spaceborne monitoring of cloud and rain hydrometeor size distributions

The aim of this thesis is to investigate possible methodologies for the monitoring of atmospheric hydrometeor size distributions from space, in particular cloud and rain sized drops. The focus on spaceborne instruments is important because they offer the only reasonable means for making observations over the whole globe, including measurements over the world's oceans and above the numerous other inaccessible areas.; Firstly, we must consider what type or types of instruments are best suited to make such measurements, and what bands in the electromagnetic spectrum are most appropriate. Every system has its advantages and disadvantages. The main criterion for the suitability of any given system is to what extent its measurements can uniquely determine the main characteristics of the underlying size distribution. The main difficulty in the problem is the proper accounting for all source of deterministic ambiguity and random error in the measurements and in their relationship to the hydrometeor size distributions.; Moreover, the nature of the uncertainties suggests that such methodologies are best considered in a stochastic framework. This is made clear by considering the major sources of randomness and their impact on the deterministic retrieval of size distribution characteristics from the various combinations of measurements. Finally, a stochastic framework is presented, along with the results from a number of simulations of possible retrieval methodologies.