A recent study published in Advances in Atmospheric Sciences has uncovered a detailed mechanism through which intense storms over the Himalayas contribute to increasing moisture in the lower stratosphere—a layer of the atmosphere crucial to global climate regulation. The research, led by PhD student LI Ming and Dr. WU Xue from the Institute of Atmospheric Physics (IAP) at the Chinese Academy of Sciences, highlights the important role of gravity waves generated by deep convection.

Photograph from the International Space Station showing an overshooting storm with an anvil and above-anvil cirrus plume. Image courtesy of the International Space Station (ISS) (ESA/NASA).

Stratospheric water vapor influences the Earth’s radiation balance, ozone chemistry, and atmospheric circulation. While it is known that some powerful storms can push moisture into the stratosphere, the exact processes over the Himalayan region—a hotspot for such storms during the Asian summer monsoon—have remained unclear.

Using high-resolution satellite data and numerical modeling, the team found that overshooting storms over the southern slope of the Himalayas excite gravity waves. These waves break and cause turbulent mixing, allowing more water vapor and ice particles to move between atmospheric layers. Additionally, the waves enhance wind shear, which promotes the formation and spread of “above-anvil cirrus plumes” (AACPs)—cloud-like structures that linger in the lower stratosphere.

“What we’ve found is that these lingering ice plumes, driven by gravity waves, can add even more water vapor to the stratosphere than the initial storm top injection,” explained Dr. WU. “This turns AACPs into a key indicator of stratospheric moistening.”

The study, which combines CloudSat observations with high-resolution topography-sensitive simulations, offers new insights into how the Tibetan Plateau region influences upper-atmosphere humidity. The team plans to integrate multi-satellite and ground-based observations—including measurements from the Atmosphere Profiling Synthetic Observation System (APSOS) station —to further investigate cloud processes and troposphere-stratosphere interactions. The APSOS was built by authors' home institute IAP In 2017. It was located about 90 km northwest of the city of Lhasa (30.21°N, 90.43°E; 4300 m MSL).

Paper info:

Li, M., Wu, X., et al. (2026). Mechanisms of Hydrating the Lower Stratosphere by Overshooting Convection over the Southern Slope of the Himalayas. Advances in Atmospheric Sciences. https://doi.org/10.1007/s00376-025-5466-6