- Institute for Atmospheric and Climate Science, ETH Zürich, Zürich, Switzerland (zhenghe.xuan@env.ethz.ch)
It is generally thought that the climate responses of El Niño-Southern Oscillation (ENSO) variability and precipitation variability are tightly linked. The reasoning is that ENSO variability leads to sea-surface temperatures and surface heat flux variability, affecting the net-energy input (NEI) and thereby precipitation. We show that equally important are changes in the gross moist stability (GMS), which is the sensitivity of the atmospheric circulation to changes in the NEI. We analyze the variance of vertical velocity in monthly outputs of the Community Earth System Model 2 Large Ensemble. Under the SSP3-7.0 scenario, we find that variance of vertical velocity changes result from the competition of spatially varying responses of NEI variance and GMS. While NEI variance changes are complex and influenced by many mechanisms such as ENSO and radiative feedbacks, GMS increases in the sub-tropics can be explained by the rising tropopause and GMS decreases near the equator can be can be explained by the enhanced heating and moistening of the near-surface eastern equatorial Pacific. Together, these changes have important implications for future changes in precipitation variability in the tropics.
How to cite: Xuan, Z., Kroll, C., and Jnglin Wills, R.: Competing influences of energy budget variability and gross moist stability on tropical circulation variance under climate change, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15963, https://doi.org/10.5194/egusphere-egu25-15963, 2025.