当前位置: X-MOL 学术npj Clim. Atmos. Sci. › 论文详情
Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)
Aerosol-induced modification of organised convection and top-of-atmosphere radiation
npj Climate and Atmospheric Science ( IF 9 ) Pub Date : 2019-09-04 , DOI: 10.1038/s41612-019-0089-1
Nidhi Nishant , Steven C. Sherwood , Olivier Geoffroy

Aerosol effects on cloud cover and precipitation could affect the global climate but have proven difficult to verify, because cloud and rain amounts are so strongly influenced by local meteorological conditions. Here model and observational evidence is presented that an increase in CCN concentration slightly invigorates mixed-phase convective clouds and narrows tropical convergence and rain bands, while expanding associated cloud cover particularly at mid-levels. A suite of model simulations with various approaches indicates a 4 ± 3.8% decrease in the rain-to-cloud area ratio per doubling of the CCN concentration, an effect also detected in satellite observations. Idealised numerical experiments suggest the area ratio change is due to the invigoration-induced static stability increase. Although the invigoration and cloud amount changes are much smaller than suggested in some studies, in simulations the latter cool the planet by 0.71 ± 0.25 W/m2 in deep convective regions, suggesting a global effect of order 0.2–0.5 W/m2, per aerosol doubling. The contribution to present-day anthropogenic forcing is even harder to quantify but could compare to that of the direct aerosol radiative forcing. These results indicate a previously unrecognised pathway for aerosols to indirectly cool the climate by altering convective clouds dynamically.



中文翻译:

气溶胶引起的有组织对流和大气顶辐射的改变

气溶胶对云量和降水的影响可能会影响全球气候,但已被证明难以验证,因为云量和雨量受到当地气象条件的强烈影响。在此提供的模型和观测证据表明,CCN浓度的增加会稍微增强混合相对流云的活动,并缩小热带辐合和降雨带,同时扩大相关的云层覆盖范围,尤其是在中层。用各种方法进行的一组模型模拟表明,每增加一倍的CCN浓度,雨云面积比就会减少4±3.8%,这在卫星观测中也能检测到。理想的数值实验表明,面积比的变化是由于振兴引起的静态稳定性的提高。2在深对流区域,表明每增加一倍气溶胶,全球效应约为0.2-0.5 W / m 2。对当今人为强迫的贡献甚至更难以量化,但可以与直接气溶胶辐射强迫的贡献相比较。这些结果表明,通过动态改变对流云,气溶胶间接降低气候温度的途径是前所未有的。

更新日期:2019-09-04
down
wechat
bug