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Attribution of Chemistry-Climate Model Initiative (CCMI) ozone radiative flux bias from satellites

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العنوان: Attribution of Chemistry-Climate Model Initiative (CCMI) ozone radiative flux bias from satellites
المؤلفون: L. Kuai, K. W. Bowman, K. Miyazaki, M. Deushi, L. Revell, E. Rozanov, F. Paulot, S. Strode, A. Conley, J.-F. Lamarque, P. Jöckel, D. A. Plummer, L. D. Oman, H. Worden, S. Kulawik, D. Paynter, A. Stenke, M. Kunze
المصدر: Atmospheric Chemistry and Physics, Vol 20, Pp 281-301 (2020)
بيانات النشر: Copernicus Publications, 2020.
سنة النشر: 2020
المجموعة: LCC:Physics
LCC:Chemistry
مصطلحات موضوعية: Physics, QC1-999, Chemistry, QD1-999
الوصف: The top-of-atmosphere (TOA) outgoing longwave flux over the 9.6 µm ozone band is a fundamental quantity for understanding chemistry–climate coupling. However, observed TOA fluxes are hard to estimate as they exhibit considerable variability in space and time that depend on the distributions of clouds, ozone (O3), water vapor (H2O), air temperature (Ta), and surface temperature (Ts). Benchmarking present-day fluxes and quantifying the relative influence of their drivers is the first step for estimating climate feedbacks from ozone radiative forcing and predicting radiative forcing evolution. To that end, we constructed observational instantaneous radiative kernels (IRKs) under clear-sky conditions, representing the sensitivities of the TOA flux in the 9.6 µm ozone band to the vertical distribution of geophysical variables, including O3, H2O, Ta, and Ts based upon the Aura Tropospheric Emission Spectrometer (TES) measurements. Applying these kernels to present-day simulations from the Chemistry-Climate Model Initiative (CCMI) project as compared to a 2006 reanalysis assimilating satellite observations, we show that the models have large differences in TOA flux, attributable to different geophysical variables. In particular, model simulations continue to diverge from observations in the tropics, as reported in previous studies of the Atmospheric Chemistry Climate Model Intercomparison Project (ACCMIP) simulations. The principal culprits are tropical middle and upper tropospheric ozone followed by tropical lower tropospheric H2O. Five models out of the eight studied here have TOA flux biases exceeding 100 mW m−2 attributable to tropospheric ozone bias. Another set of five models have flux biases over 50 mW m−2 due to H2O. On the other hand, Ta radiative bias is negligible in all models (no more than 30 mW m−2). We found that the atmospheric component (AM3) of the Geophysical Fluid Dynamics Laboratory (GFDL) general circulation model and Canadian Middle Atmosphere Model (CMAM) have the lowest TOA flux biases globally but are a result of cancellation of opposite biases due to different processes. Overall, the multi-model ensemble mean bias is -133±98 mW m−2, indicating that they are too atmospherically opaque due to trapping too much radiation in the atmosphere by overestimated tropical tropospheric O3 and H2O. Having too much O3 and H2O in the troposphere would have different impacts on the sensitivity of TOA flux to O3 and these competing effects add more uncertainties on the ozone radiative forcing. We find that the inter-model TOA outgoing longwave radiation (OLR) difference is well anti-correlated with their ozone band flux bias. This suggests that there is significant radiative compensation in the calculation of model outgoing longwave radiation.
نوع الوثيقة: article
وصف الملف: electronic resource
اللغة: English
تدمد: 1680-7316
1680-7324
Relation: https://www.atmos-chem-phys.net/20/281/2020/acp-20-281-2020.pdf; https://doaj.org/toc/1680-7316; https://doaj.org/toc/1680-7324
DOI: 10.5194/acp-20-281-2020
URL الوصول: https://doaj.org/article/1c86cd4e6a034aed9bc1893ed60d400e
رقم الأكسشن: edsdoj.1c86cd4e6a034aed9bc1893ed60d400e
قاعدة البيانات: Directory of Open Access Journals
الوصف
تدمد:16807316
16807324
DOI:10.5194/acp-20-281-2020