Influence of the Antarctic Oscillation (AAO) upon atmospheric circulations in the Northern Hemisphere through the Somali Jet
Abstract
The Antarctic Oscillation (AAO) is the leading mode of atmospheric variations in the middle to high latitudes of the Southern Hemisphere. Some studies showed the AAO remotely controls tropical convective cloud activity (e.g., Eguchi and Kodera, 2007; Kodera et al., 2011), or the existence of in-phase synchronization between the AAO and Artic Oscillation (Tachibana et al., 2018). These studies focused only on stratospheric circulations. Present study examine whether the AAO remotely controls atmospheric circulations in the Northern Hemisphere (NH) through interhemispheric tropospheric circulations. We hypothesized that a candidate connecting both hemispheres is Somali Jet (SMJ), which influences on the interhemispheric water vapor transport and the East Asian summer climate.
Data analyses showed that the AAO in December - February (DJF) strengthens SMJ in May, June (MJ). Positive sea surface temperature (SST) and enhanced convective activity anomalies associated with the AAO in DJF were apparent in the South Indian Ocean. This SST driven convective activity persisted until MJ. A simple linear baroclinic numerical experiment showed that the enhancement of convective activity due to the positive SST anomalies intensifies the SMJ. The AAO-driven SMJ further increased precipitation and diabatic heating over Indo. This diabatic heating moreover activated anomalous atmospheric circulations over East Asia. We suggest that the AAO in DJF might control the large-scale atmospheric circulation in the mid-latitude over the NH in MJ through the SMJ variations. References Eguchi, N. and K. Kodera, (2007), GRL, 34, L05819. https://doi.org/10.1029/2006GL028744 Kodera, K. et al., (2011), JMSJ, 89, 283-290. https://doi.org/10.2151/jmsj.2011-308 Tachibana, Y. et al., (2018), GRL, 45, 13477-13484. https://doi.org/10.1029/2018GL081002- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.A43N3086S
- Keywords:
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- 3305 Climate change and variability;
- ATMOSPHERIC PROCESSES;
- 3319 General circulation;
- ATMOSPHERIC PROCESSES;
- 3320 Idealized model;
- ATMOSPHERIC PROCESSES;
- 3337 Global climate models;
- ATMOSPHERIC PROCESSES