Atmospheric rivers, channels of intense moisture movement, significantly impact extreme precipitation, particularly in coastal areas. However, the challenge of detecting these rivers in satellite observations arises due to the absence of wind information.
A recent breakthrough discussed in a paper, titled "Evaluating the Representations of Atmospheric Rivers and Their Associated Precipitation in Reanalyses with Satellite Observations" published in the Journal of Geophysical Research: Atmospheres, used satellite temperature distribution to detect atmospheric rivers in 3D wind fields, creating a groundbreaking global dataset.
An atmospheric river originating from Hawaii, dubbed a Pineapple Express, affecting California on April 7, 2018.
Impact of Atmospheric Moisture Highways on Global Precipitation and Climate Dynamics
Atmospheric rivers carry vital moisture that significantly contributes to annual precipitation across regions. They account for up to 30% of the yearly rainfall in the US and Europe, with figures rising to 40% during East Asia's wet season.
Originating over tropical oceans, these rivers pose weather hazards such as damaging winds and flooding upon reaching land. The shifting jet stream has led to increased atmospheric river frequency over the eastern US in the last four decades.
Despite variations in size, an average atmospheric river carries water vapor equivalent to the flow at the mouth of the Mississippi River, with exceptionally strong ones transporting up to 15 times that amount. Their landfall often results in the release of water vapor as rain or snow. Atmospheric rivers significantly impact sea ice variability, contributing to record lows at both poles in recent years.
Varying in size, they can lead to extreme rainfall, floods, and damage when stalling over vulnerable areas. The 'Pineapple Express,' a robust atmospheric river, exemplifies this, transporting moisture from the tropics to the US West Coast. Despite potential damage, not all are destructive; many bring beneficial rain or snow crucial for water supply.
Playing a key role in the global water cycle, they impact water supply and flood risks, especially in the western US. While they can induce flooding, atmospheric rivers also contribute positively to snowpack. NOAA's research, using various observations, aids in forecasting heavy rain and potential flooding up to seven days in advance for the National Weather Service.
READ ALSO: Atmospheric Rivers Can Cause Extreme And Most Dangerous Storms In California
Revolutionizing Atmospheric River Detection: A Novel Method Using Satellites
Using a groundbreaking technique to estimate 3D wind data through satellites, scientists can now automatically detect atmospheric rivers using satellite observations, generating a comprehensive global AR dataset.
Their study reveals that existing atmospheric river data tends to overestimate precipitation frequency but underestimate its intensity. The developed atmospheric rivers detection algorithm, incorporating 3D wind information from satellites, provides a more accurate understanding of impending extreme weather events globally.
The findings expose the limitations of previous atmospheric river analyses, offering insights to enhance the representation of ARs and associated precipitation in reanalyses and climate models. As satellite observation quality improves, the methodology can be extended for higher-resolution or higher-frequency AR statistics.
Examining the visible sky streams, University of California atmospheric scientist Weiming Ma and the team identified that previous models overestimated the frequency of rain from atmospheric rivers while underestimating its intensity.
The research emphasizes the potential application of the new methodology to other satellite observations, enabling the development of more precise atmospheric river statistics. Integrating this innovative method into weather forecasts and climate models, the researchers plan to assess how climate models align with their approach to atmospheric river detection in future evaluations.
RELATED ARTICLE: Atmospheric Rivers: What Are They and How Do They Affect Us?
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