The QBO–MJO Connection: A Possible Role for the SST and ENSO

Journal Article · 24 August 2023 · Journal of Climate

DOI: https://doi.org/10.1175/jcli-d-23-0031.1 · OSTI ID:2424881

Randall, David A.  ^[1]; Tziperman, Eli ^[2]; Branson, Mark D. ^[1]; Richter, Jadwiga H. ^[3]; Kang, Wanying ^[4]

---

1. Colorado State University, Fort Collins, CO (United States)
2. Harvard University, Cambridge, MA (United States)
3. National Center for Atmospheric Research, Boulder, CO (United States)
4. Massachusetts Institute of Technology (MIT), Cambridge, MA (United States)

We examine the hypothesis that the observed connection between the stratospheric quasi-biennial oscillation (QBO) and the strength of the Madden–Julian oscillation (MJO) is modulated by the sea surface temperature (SST)—for example, by El Niño–Southern Oscillation (ENSO). A composite analysis shows that, globally, La Niña SSTs are remarkably similar to those that occur during the easterly phase of the QBO. A maximum covariance analysis suggests that MJO power and SST are strongly linked on both the ENSO time scale and the QBO time scale. We analyze simulations with a modified configuration of version 2 of the Community Earth System Model, with a high top and fine vertical resolution. The model is able to simulate ENSO, the QBO, and the MJO. The ocean-coupled version of the model simulates the QBO, ENSO, and MJO, but does not simulate the observed QBO–MJO connection. When driven with prescribed observed SST anomalies based on composites for QBO east and QBO west (QBOE and QBOW), however, the same atmospheric model produces a modest enhancement of MJO power during QBOE relative to QBOW, as observed. We explore the possibility that the SST anomalies are forced by the QBO itself. Indeed, composite Hovmöller diagrams based on observations show the propagation of QBO zonal wind anomalies all the way from the upper stratosphere to the surface. Also, subsurface ocean temperature composites reveal a similarity between the western Pacific and Indian Ocean subsurface signal between La Niña and QBOE.

• Research Organization: National Center for Atmospheric Research (NCAR), Boulder, CO (United States)
• Sponsoring Organization: National Science Foundation (NSF); USDOE Office of Science (SC), Biological and Environmental Research (BER)
• OSTI ID: 2424881
• Journal Information: Journal of Climate, Journal Name: Journal of Climate Journal Issue: 18 Vol. 36; ISSN 0894-8755
• Publisher: American Meteorological SocietyCopyright Statement
• Country of Publication: United States
• Language: English