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Impact of dust in PMIP-CMIP6 mid-Holocene simulations with the IPSL model
Climate of the Past ( IF 4.3 ) Pub Date : 2021-05-26 , DOI: 10.5194/cp-17-1091-2021
Pascale Braconnot , Samuel Albani , Yves Balkanski , Anne Cozic , Masa Kageyama , Adriana Sima , Olivier Marti , Jean-Yves Peterschmitt

We investigate the climate impact of reduced dust during the mid-Holocene using simulations with the IPSL model. We consider simulations where dust is either prescribed from an IPSL PI simulation or from CESM simulations (Albani et al., 2015). In addition, we also consider an extreme mid-Holocene case where dust is suppressed. We focus on the estimation of the dust radiative effects and the relative responses of the African and Indian monsoon, showing how local dust forcing or orography affect atmospheric temperature profiles, humidity and precipitation. The simulated mid-Holocene climate is statistically different in many regions compared to previous mid-Holocene simulations with the IPSL models. However, it translates to only minor improvements compared to palaeoclimate reconstructions, and the effect of dust has little impact on mid-Holocene model skill over large regions. Our analyses confirm the peculiar role of dust radiative effect over bright surfaces such as African deserts compared to other regions, brought about by the change of sign of the dust radiative effect at the top of atmosphere for high surface albedo. We also highlight a strong dependence of results on the dust pattern. In particular, the relative dust forcing between West Africa and the Middle East impacts the relative climate response between India and Africa and between Africa, the western tropical Atlantic and the Atlantic meridional circulation. It also affects the feedback on the Atlantic Ocean thermohaline circulation. Dust patterns should thus be better constrained to fully understand the changes in the dust cycle and forcing during the mid-Holocene, which also informs on the potential changes in key dust feedbacks in the future.

中文翻译:

使用IPSL模型在PMIP-CMIP6全新世中期模拟中灰尘的影响

我们使用IPSL模型进行模拟,研究了全新世中期尘埃减少对气候的影响。我们考虑采用IPSL PI模拟或CESM模拟规定粉尘的模拟(Albani等,2015)。此外,我们还考虑了极端中全新世的情况,其中灰尘被抑制。我们集中于对非洲和印度季风的尘埃辐射效应和相对响应的估计,显示了局部尘埃强迫或地形如何影响大气温度分布,湿度和降水。与以前使用IPSL模型进行的全新世中期模拟相比,许多地区的全新世中期模拟气候在统计上有所不同。但是,与古气候重建相比,这仅意味着较小的改进,灰尘的影响对大区域中全新世模型的技能影响不大。我们的分析证实,与其他地区相比,尘埃辐射效应在诸如非洲沙漠之类的明亮表面上具有特殊作用,这是由于高表面反照率在大气顶部的尘埃辐射效应的符号变化引起的。我们还强调了结果对尘埃模式的强烈依赖性。特别是,西非和中东之间的相对扬尘影响印度和非洲之间以及非洲,热带西大西洋和​​大西洋子午线环流之间的相对气候响应。它还影响对大西洋热盐循环的反馈。因此,应更好地限制尘埃分布,以充分了解全新世中期尘埃循环和强迫的变化,
更新日期:2021-05-26
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