How the Madden-Julian Oscillation Shapes the Upper Atmosphere
- Federico Gasperini
- Sep 23
- 3 min read
Updated: Oct 7
Federico Gasperini, Research Scientist
In recent years, scientific discoveries have revealed intriguing connections between Earth’s lower atmosphere and the dynamics of the thermosphere, the upper region of our atmosphere extending above 100 kilometers. One of the most fascinating links is how tropical weather systems, particularly the periodic Madden-Julian Oscillation (MJO), create rippling effects that propagate all the way to the thermosphere. These perturbations also significantly impact the ionosphere, degrading communications, GPS and radar systems, while thermospheric variability drives uncertainties in satellite drag, conjunction analysis and reentry.
A recent Orion study investigates this remarkable connection using advanced modeling and satellite data. The study highlights how solar tides, generated by tropical weather systems like the MJO, interact with the thermosphere, leading to intra-seasonal oscillations (ISOs) in the thermosphere. By integrating data from NASA’s Ionospheric Connection Explorer (ICON) mission into Orion’sThermosphere Ionosphere Electrodynamics General Circulation Model (TIEGCM), the team has discovered new insights into this atmosphere-wide connection.
A CLOSER LOOK AT THE MADDEN-JULIAN OSCILLATION AND SOLAR TIDES
The MJO is a prominent weather phenomenon in the tropics, characterized by atmospheric convection and circulation patterns that occur on intra-seasonal timescales of 30 to 90 days. The MJO is not confined to the lower atmosphere; its influence extends upward through thermal tides—regular variations in atmospheric density and motion caused by solar heating and latent heat release from tropical convection.
These solar tides act as a mechanism for transferring energy, momentum and variability from the troposphere to the thermosphere. While the connection between the MJO and thermospheric dynamics has long been hypothesized, advances in satellite technology, particularly through the ICON mission, allowed researchers to investigate this coupling with unprecedented detail.
FINDINGS FROM ICON-ENHANCED MODELING
Using an enhanced version of the TIEGCM model, which incorporates data from ICON’s Michelson Interferometer for Global High-resolution Thermospheric Imaging (MIGHTI), Gasperini’s study explored how solar tides driven by the MJO impact the thermosphere. The study focused on the thermospheric “gap” region, located between 100 and 300 kilometers altitude, and revealed significant oscillations in east-west winds at altitudes of 110 to 150 kilometers.
The findings show that these wind variations, with amplitudes of more than 20 meters per second, correlate strongly with periodic patterns in the lower atmosphere driven by the MJO. The research also quantified the connection, finding that thermospheric variability in the diurnal eastward nonmigrating tide (DE3), primarily excited by latent heating from tropical convection, shares about 38 percent of its variance with the Real-Time Multivariate MJO index, a metric used to measure the strength of the MJO.
IMPLICATIONS FOR WHOLE-ATMOSPHERE DYNAMICS
This study underscores the role of vertically propagating thermal tides in establishing a connection between the lower and upper layers of Earth’s atmosphere. The MJO, a key driver of tropical weather, acts as a bridge, transferring variability from the troposphere to the thermosphere through upward-propagating tides.
These findings advance our understanding of the fundamental processes that drive atmospheric coupling across varied altitudes. They also demonstrate the importance of filling observational gaps in the thermosphere, a region that has historically been undersampled due to technical limitations. The integration of ICON data into TIEGCM modeling represents a significant step forward in addressing this challenge.
WHY IT MATTERS
Understanding how energy and variability propagate from the lower to upper atmosphere has wide-reaching implications for space weather prediction, satellite operations and even global circulation models. By showing how intra-seasonal variability in the tropics impacts thermospheric dynamics, this study contributes to our knowledge of how Earth’s atmosphere functions as an interconnected system.
Our atmosphere is not just a collection of isolated layers; it is a dynamic, interconnected system where events in the lower atmosphere can shape space weather and influence the regions where satellites orbit. This work highlights the power of modern satellite missions like ICON in unraveling these connections, bringing us closer to a comprehensive understanding of Earth’s atmospheric processes.
Click the link below to view the poster presentation of this work.
Federico Gasperini is a research scientist at Orion Space Solutions, an Arcfield company, studying the dynamics of Earth’s and Mars’ upper atmospheres. His research explores how tides, waves and space weather link the lower atmosphere and ionosphere, with applications from satellite drag prediction to climate impacts. He holds a Ph.D. in aerospace engineering sciences from the University of Colorado Boulder and has held fellowships at the National Center for Atmospheric Research, Utah State University and Los Alamos National Laboratory. Recognized with honors such as the NCAR Advanced Study Program Fellowship, he has more than a decade of published research advancing atmospheric and ionospheric science.
