Observing and Detecting Atmospheric Rivers: From Satellites to Aircraft, Radars, AR Observatories, Regional Mesonets, Reanalyses, and AR Detection Methods

How do we observe and detect ARs? Observing systems provide ground truth of the main AR ingredients, such as water vapor and wind, and process information on AR mechanisms and effects. Gridded atmospheric reanalysis products allow us to study ARs from historical, regional, and global perspectives. Detection methods are also critical to identifying ARs in regional and global models in order to evaluate their performance in simulating and predicting ARs, as well as to determine how ARs will behave in the future, based on global climate projections. The first three sections of this chapter describe some of the observing technologies used to monitor ARs, such as (1) satellite data, which help to provide a global context; (2) AR observatories: land-based collections of instruments that help track ARs as they make landfall; (3) other ground-based observations that track ARs as they penetrate inland; (4) airborne and other measurements from major research field experiments devoted to understanding ARs, as well as AR Reconnaissance (Recon) airborne efforts to better predict ARs; (5) the representation of ARs in reanalyses; and (6) the evolution of methods used to identify ARs and describes some of the AR climatologies that have been created using these techniques.