Abstract
Stratospheric water vapor (SWV) changes play an important role in regulating global climate change, and its variations are controlled by tropopause temperature. This study estimates the impacts of tropopause layer ozone changes on tropopause temperature by radiative process and further influences on lower stratospheric water vapor (LSWV) using the Whole Atmosphere Community Climate Model (WACCM4). It is found that a 10% depletion in global (mid-low and polar latitudes) tropopause layer ozone causes a significant cooling of the tropical cold-point tropopause with a maximum cooling of 0.3 K, and a corresponding reduction in LSWV with a maximum value of 0.06 ppmv. The depletion of tropopause layer ozone at mid-low latitudes results in cooling of the tropical cold-point tropopause by radiative processes and a corresponding LSWV reduction. However, the effect of polar tropopause layer ozone depletion on tropical cold-point tropopause temperature and LSWV is opposite to and weaker than the effect of tropopause layer ozone depletion at mid-low latitudes. Finally, the joint effect of tropopause layer ozone depletion (at mid-low and polar latitudes) causes a negative cold-point tropopause temperature and a decreased tropical LSWV. Conversely, the impact of a 10% increase in global tropopause layer ozone on LSWV is exactly the opposite of the impact of ozone depletion. After 2000, tropopause layer ozone decreased at mid-low latitudes and increased at high latitudes. These tropopause layer ozone changes at different latitudes cause joint cooling in the tropical cold-point tropopause and a reduction in LSWV. Clarifying the impacts of tropopause layer ozone changes on LSWV clearly is important for understanding and predicting SWV changes in the context of future global ozone recovery.
Highlights
As an important greenhouse gas (GHG), stratospheric water vapor (SWV) changes have attracted much attention [1,2,3] and play an important role in regulating the global radiation budget, energy balance, stratospheric temperature and chemical process, and global climate change [4,5,6]
Compared to experiment R0, in which tropopause layer ozone concentrations at mid-low latitudes are reduced by 10% (R2), the cold-point tropopause cooling in Figure 2b is stronger than that in Figure 2a between 30◦ S and 30◦ N
A comparison of Figure 2a–c reveals that the depletion in tropopause layer ozone at mid-low latitudes leads to the most drastic cooling of the tropical cold-point tropopause, and the effect of polar tropopause layer ozone depletion on the tropical cold-point tropopause temperature is reversed and weaker compared to the effect of tropopause layer ozone depletion at mid-low latitudes
Summary
As an important greenhouse gas (GHG), stratospheric water vapor (SWV) changes have attracted much attention [1,2,3] and play an important role in regulating the global radiation budget, energy balance, stratospheric temperature and chemical process, and global climate change [4,5,6]. Tropical tropopause temperature is the main factor controlling tropical SWV through dehydration [1,8,9,10,11], as determined by radiative, chemical, and dynamical processes in the tropical tropopause layer (TTL) [12,13]. Xie et al [34] showed that a 15% global ozone decrease can induce lower tropopause temperatures and decrease stratospheric water vapor using a general circulation model These studies mainly focused on the responses of global ozone variations to TTL temperature and LSWV.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
