Atmospheric Trace Gases as Probes of Chemistry and Dynamics

• Main Author: Li, King-Fai
• Format: Thesis
• Language: English
• Published: 2013
• Subjects: Arctic
• Online Access: https://thesis.library.caltech.edu/7186/; https://thesis.library.caltech.edu/7186/1/kfl_thesis_v02.pdf; https://resolver.caltech.edu/CaltechTHESIS:08172012-154924604

This dissertation is a collection of empirical and modeling studies focusing on decadal and intraseasonal variabilities in atmospheric tracers. In Part I, a persistent discrepancy between the model and observed stratospheric O 3 solar response is revisited using the Whole-Atmosphere Community Chemistry Model (WACCM). The model O 3 simulated using UV irradiances measured from the latest spaceborne solar UV measurements by the Solar Radiation and Climate Experiment (SORCE) and that from the solar UV parametrization developed by the Naval Research Laboratory (NRL) are studied and compared with observations. None of the simulations using SORCE and NRL UV simultaneously agree with the observed O 3 solar response in both upper and lower stratospheres, thus presenting a dilemma to our current understanding of stratospheric O 3 response to UV perturbations. However, the simulation using the SORCE UV irradiance leads to a solar response in upper stratospheric/lower mesospheric OH column that agrees better than those derived from ground-based and satellite observations. Continuous long-term observations of solar UV, OH, O 3 , and other related chemical species through upcoming solar cycles are crucial for further investigations to solve the above puzzles. In Part II, intraseasonal variabilities in upper tropospheric/lower stratospheric (UTLS) O 3 and mid-tropospheric carbon dioxide (CO 2 ) related to the Madden-Julian oscillation (MJO) are studied using recent satellite observations. The UTLS O 3 at mid-latitudes is shown to be modulated by the MJO through dynamical motions of the tropopause layer, supporting the conjecture proposed in previous studies. It is further shown that the UTLS O 3 over the Arctic can be also modulated by the tropopause motions through MJO teleconnections. On the other hand, the distribution of tropical mid-tropospheric CO 2 is modulated by the MJO through upward transport of surface CO 2 . The amplitude is of critical scale for identifying oceanic and land sources of CO 2 . The detailed ...