Affiliation:
1. Department of Atmospheric Science Colorado State University Fort Collins CO USA
2. Climate and Global Dynamics Laboratory National Center for Atmospheric Research Boulder CO USA
3. Program in Atmospheric and Oceanic Science Princeton University Princeton NJ USA
4. NASA Goddard Institute for Space Studies New York NY USA
5. Lawrence Livermore National Laboratory Livermore CA USA
6. Department of Science Education Ewha Womans University Seoul Republic of Korea
7. School of Marine and Atmospheric Sciences Stony Brook NY USA
8. Atmospheric Sciences and Global Change Pacific Northwest National Laboratory Richland WA USA
Abstract
AbstractThe observed stratospheric quasi‐biennial oscillation (QBO) and the tropospheric Madden‐Julian oscillation (MJO) are strongly connected in boreal winter, with stronger MJO activity when lower‐stratospheric winds are easterly. However, the current generation of climate models with internally generated representations of the QBO and MJO do not simulate the observed QBO‐MJO connection, for reasons that remain unclear. This study builds on prior work exploring the QBO‐MJO link in climate models whose stratospheric winds are relaxed toward reanalysis, reducing stratospheric biases in the model and imposing a realistic QBO. A series of ensemble experiments are performed using four state‐of‐the‐art climate models capable of representing the MJO over the period 1980–2015, each with similar nudging in the stratosphere. In these four models, nudging leads to a good representation of QBO wind and temperature signals, however no model simulates the observed QBO‐MJO relationship. Biases in MJO vertical structure and cloud‐radiative feedbacks are investigated, but no conclusive model bias or mechanism is identified that explains the lack of a QBO‐MJO connection.
Funder
National Science Foundation
National Oceanic and Atmospheric Administration
National Center for Atmospheric Research
Biological and Environmental Research
U.S. Department of Energy
Office of Science
Lawrence Livermore National Laboratory
Laboratory Directed Research and Development
Goddard Institute for Space Studies
National Aeronautics and Space Administration
Goddard Space Flight Center
Publisher
American Geophysical Union (AGU)
Subject
Space and Planetary Science,Earth and Planetary Sciences (miscellaneous),Atmospheric Science,Geophysics