Hello! I’m Jian Guan (关健), a Ph.D. candidate in the Department of Earth, Atmospheric, and Planetary Sciences at MIT, working with Prof. Susan Solomon . My research focuses on stratospheric chemistry, particularly on understanding the drivers of stratospheric variability and long-term change.

My work spans several key areas:

1. Ozone depletion and recovery – I study the detection and variability of ozone trends using large initial-condition ensembles, both from the Community Earth System Model (CESM) and multi-model ensembles from the Chemistry–Climate Model Initiative (CCMI). I also apply the standard “fingerprint” method to distinguish anthropogenic signals from internal variability.
2. Photolysis of secondary organic aerosols (SOA) – I investigate how SOA break down under sunlight in the stratosphere by combining field and satellite observations with simulations using CESM’s Modal Aerosol Model (CESM-MAM) and the Community Aerosol and Radiation Model for Atmospheres (CARMA).
3. Photolysis of NO₂ – I study NO₂ photolysis in the stratosphere using satellite observations from the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) and validate the results with the Tropospheric Ultraviolet and Visible (TUV) radiation module within CESM.

Outside of research, I enjoy weightlifting, hiking, and playing basketball.