Tropical cyclones (TC) are the most severe storm systems on Earth and can cause significant loss of life and property upon landfall in coastal areas. A better understanding of their variability mechanisms will help improve TC seasonal prediction skill and help hurricane preparedness and mitigation, especially when storm impacts are predicted to worsen with increasing sea level and water vapor capacity in a warming climate.
Slowly varying tropical oceanic conditions have been considered as a primary source of predictability for TC activity, but recent studies suggest that TC activity is also subject to some long-range impacts of extratropical processes.
In a new PNAS article, authors Zhuo Wang, Gan Zhang, Timothy J. Dunkerton, and Fei-Fei Jin, show that stationary waves in the Northern Hemisphere integrate tropical and extratropical impacts on TC activity from July through October. In particular, tropical upper-tropospheric troughs (TUTTs), as part of the summertime stationary waves, are associated with the variability of large-scale environmental conditions in the tropical North Atlantic and North Pacific. TUTTs are characterized by a cold-core, shallow structure in the upper troposphere and are present over the North Pacific and North Atlantic in boreal summer and extend equatorward and westward from the subtropics to the tropics.
Researchers demonstrate the strong link between TUTTs and TC activity over the North Pacific and North Atlantic. Additionally, TUTTs are related to tropical and extratropical SST and precipitation anomalies in various regions, including the ENSO and monsoons. This study advocates a hemispheric perspective that helps researchers understand the variability and predictability of TC activity over the North Atlantic and North Pacific. This view may also help researchers understand the projection of TC activity in future climates.
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About MAPP
The Modeling, Analysis, Predictions, and Projections (MAPP) Program is a competitive research program in NOAA Research’s Climate Program Office. MAPP’s mission is to enhance the Nation’s and NOAA’s capability to understand, predict, and project variability and long-term changes in Earth’s system and mitigate human and economic impacts. To achieve its mission, MAPP supports foundational research, transition of research to applications, and engagement across other parts of NOAA, among partner agencies, and with the external research community. MAPP plays a crucial role in enabling national preparedness for extreme events like drought and longer-term climate changes. For more information, please visit www.cpo.noaa.gov/MAPP.