Phys.org February 19, 2024
Atmospheric rivers (ARs) are filaments of enhanced horizontal moisture transport in the atmosphere. They play a prominent role in the meridional moisture transport and regional weather extremes. But the representations of ARs and their associated precipitation on a global scale remains largely unknown. A team of researchers in the US (UCLA, NCAR, Caltech) developed an AR detection algorithm specifically for satellite observations using moisture and the geostrophic winds derived from 3D geopotential height field from the combined retrievals of the Atmospheric Infrared Sounder and the Advanced Microwave Sounding Unit on NASA Aqua satellite. The algorithm enabled development of the first global AR catalog based solely on satellite observations. The catalog was combined with the satellite-based precipitation to evaluate the representations of ARs and AR-induced precipitation in reanalysis products. Their results showed that the spreads in AR frequency and AR length distribution are generally small across data sets, while the spread in AR width is relatively larger. Reanalysis products are found to consistently underestimate both mean and extreme AR-related precipitation. However, all reanalyzes tend to precipitate too often under AR conditions, especially over low latitude regions. This finding was consistent with the “drizzling” bias. According to the researchers their study can help to improve the representations of ARs and associated precipitation in reanalyzes and climate models… read more. TECHNICAL ARTICLE
Atmospheric rivers, filaments of intense moisture transport in the atmosphere… Credit: NOAA