Abstract During boreal winter, the climatological stationary wave plays a key role in the poleward transport of heat in mid- and high latitudes. Latent heating is an important driver of boreal-winter stationary waves. In this study, the temporal relationship between tropical and extratropical heating and transient–stationary wave interference is investigated by performing observational data analyses and idealized model experiments. In line with stationary wave theory, the observed heating anomaly fields during constructive interference events have a spatial structure that reinforces the zonal asymmetry of the climatological heating field. The observational analysis shows that about 10 days prior to constructive interference events, tropical heating anomalies are established, and within 1 week North Pacific and then North Atlantic heating anomalies follow. This result suggests that constructive interference involves a heating–circulation relay: tropical latent heating drives circulation anomalies that transport moisture in such a manner as to increase latent heating in the North Pacific; circulation anomalies driven by this North Pacific heating similarly lead to enhanced latent heating in the North Atlantic. This heating–circulation relay picture is supported by initial-value model calculations in which the observed heating anomalies are used to drive model circulations. Our results also show that the constructive interference drivenmore »
Summertime stationary waves integrate tropical and extratropical impacts on tropical cyclone activity
Tropical cyclones (TC) are one of the most severe storm systems on Earth and cause significant loss of life and property upon landfall in coastal areas. A better understanding of their variability mechanisms will help improve the TC seasonal prediction skill and mitigate the destructive impacts of the storms. Early studies focused primarily on tropical processes in regulating the variability of TC activity, while recent studies suggest also some long-range impacts of extratropical processes, such as lateral transport of dry air and potential vorticity by large-scale waves. Here we show that stationary waves in the Northern Hemisphere integrate tropical and extratropical impacts on TC activity in 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 and significantly correlated to the variability of TC activity in these basins. TUTTs are subject to the modulation of diabatic heating in various regions and are the preferred locations for extratropical Rossby wave breaking (RWB). A strong TUTT in a basin is associated with enhanced RWB and tropical−extratropical stirring in that basin, and the resultant changes in the tropical atmospheric conditions more »
- Award ID(s):
- 1813611
- Publication Date:
- NSF-PAR ID:
- 10298425
- Journal Name:
- Proceedings of the National Academy of Sciences
- Volume:
- 117
- Issue:
- 37
- Page Range or eLocation-ID:
- 22720 to 22726
- ISSN:
- 0027-8424
- Sponsoring Org:
- National Science Foundation
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Accepted Manuscript1.0
- Publisher's Version of Record
- https://doi.org/10.1073/pnas.2010547117
