Introduction to Atmospheric Rivers

Abstract

This chapter offers a brief overview of the science of atmospheric rivers (ARs), including the process that led to their formal definition, which now appears in the Glossary of Meteorology. From the 1970s through today, the emergence of the concept of the AR follows the trajectory of many scientific ideas in varied disciplines; observations of the physical characteristics of certain phenomena lead to gradual refinements in theory as the community grapples with the topic and aggregates shared scholarship. For this particular concept-the AR-evolving technology has played a huge role: from field campaigns conducted via specially equipped jets, the advent of satellites capable of returning specialized images and data sets from around the world, and the development of atmospheric reanalysis products based on advanced data assimilation methods using a wide and comprehensive set of in situ and satellite observations. Increasingly, these tools have enabled research to progress, and that research has in turn enabled findings to be applied to specific situations and problems. For example, ARs can be both highly beneficial (precipitation for water supply) and highly destructive (flooding and other emergencies caused by extreme weather). How ARs will affect a given region or situation depends in large part upon how accurately-and how far in advance-they can be predicted and planned for. Looking forward, a scale for AR intensity and an impact-based categorization scheme have just been developed. These and further iterative improvements that enable increasing precision and accuracy are necessary as studies increasingly address ARs and global climate change. ARs are extremely important parts of our current meteorology, climatology, and hydrology; they will likely become even more pronounced parts of the climate system in the warming climate of the future.