Effects of Atmospheric Rivers

This chapter discusses the intensity of the precipitation ARs often bring, and their unique combinations of durations, geometries, winds, and temperatures which make ARs important and unique pieces of the climatology and landscapes that affect both natural systems and human societies. Mountains profoundly affect AR conditions and processes, for instance, especially because ARs transport vast quantities of water vapor, which can result in huge amounts of precipitation. These vast quantities pose risks (flooding) and provide benefits (water resources) as well as affect aquatic ecosystems, terrestrial landscapes, surface winds, and coastal sea levels. Section 5.5 reviews the distinct regional patterns of AR effects across North America, Europe, South America, New Zealand, and the Arctic and Antarctica. Section 5.6 summarizes the key meteorological and land characteristics of ARs that most strongly determine the consequences of their landfalls and inland penetrations. Improvements in forecasting AR storms and conditions offer significant opportunities for improved ecosystem, resource, and disaster management across all sorts of landscapes and societal needs. But because ARs have their own physical and statistical properties relative to other storms and weather phenomena, recognition of their special roles in these systems will allow more targeted responses to both the risks and benefits of ARs.