DOCUMENTING AND DETECTING LONG-TERM PRECIPITATION TRENDS - WHERE WE ARE AND WHAT SHOULD BE DONE

A brief review of problems and achievements in documenting precipitati on changes during the period of instrumental measurements is presented . Concern is expressed that without appropriate studies in the coming period of a new generation of precipitation measurements, technologica l progress in instrumentation may adversely and inadvertently affect o ur capability for monitoring and detecting future changes in terrestri al precipitation. At the same time, only a new generation of instrumen tation will be capable of resolving the problems of monitoring precipi tation over oceans. Special attention is paid to validation of the inc reasing trend in terrestrial precipitation observed during the past hu ndred years at high latitudes of the northern hemisphere - a feature o f global warming predicted by most climate models.