| Abstrakt: |
The hydroxyl radical (OH) is a powerful oxidant in the troposphere controlling the atmospheric lifetimes of many short‐lived climate forcers such as methane. In this study, the GFDL‐AM4.1 model is used to investigate the meteorological impacts on OH and the methane budget and lifetime over 1980–2017. Driven by meteorological reanalyses from the National Centers for Environmental Prediction and the Modern‐Era Retrospective analysis for Research and Applications (Version 2), our model gives an 11.2 Tg yr−1 difference in the derived methane emissions and 0.24 years difference in the estimated methane lifetime. The results suggest that meteorology affects the mean OH concentrations but not OH trend, while the latter shows strong correlation with reactive nitrogen emissions. Despite the relatively small difference in global tropospheric OH (∼2%) induced by different meteorological forcings, the difference is much larger regionally, leading to a difference of 8 Tg yr−1 in tropical methane emissions. Plain Language Summary: The hydroxyl radical (OH) is extremely reactive in the atmosphere and able to destroy many other chemicals, such as methane, a strong greenhouse gas that contributes significantly to global warming. Therefore, OH is very important for methane concentrations and lifetime. Changes in the meteorological features (e.g., temperature, wind patterns, and relative humidity) would affect OH in the atmosphere. In this study, we use a three‐dimensional numerical model to understand the meteorological impacts on OH and the resulting impacts on methane budget and lifetime over 1980–2017. With different meteorological datasets, we find there is a 2% difference in global mean tropospheric OH concentrations, with much larger differences over tropics. We calculate methane sources and loss due to OH and find an 11.2 Tg yr−1 difference in the global mean methane sources with 8 Tg yr−1 difference in the tropics, and 0.24 years difference in methane lifetime between the two meteorological datasets. Key Points: Hydroxyl radical (OH) abundances vary by up to 2% globally and by larger amounts regionally (>10%) when nudged with different meteorological reanalysesMeteorology‐driven differences in OH lead to differences of 11.2 Tg yr−1 in estimated methane emissions and 0.24 years in methane lifetimeMeteorology affects OH concentrations but not the OH trend, with the latter showing strong correlation with reactive nitrogen emissions [ABSTRACT FROM AUTHOR] |
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