基于CMIP6强迫模拟分析人为气溶胶的气候效应(二)——诊断方法在分类评估中的重要性
作者:
作者单位:

作者简介:

通讯作者:

基金项目:

国家重点研发计划(2017YFA0604000);国家自然科学基金资助项目(41775095);南京信息工程大学人才启动经费(2243141601067)


A modeling study on anthropogenic aerosol effects based on CMIP6 forcing, part Ⅱ:the importance of calculation methods in classification analysis
Author:
Affiliation:

Fund Project:

  • 摘要
  • |
  • 图/表
  • |
  • 访问统计
  • |
  • 参考文献
  • |
  • 相似文献
  • |
  • 引证文献
  • |
  • 资源附件
    摘要:

    对气溶胶气候效应开展分类评估并探讨诊断方法的合理性。人为气溶胶辐射效应对计算云辐射强迫的影响为0.38 W·m-2。诊断评估气溶胶对云辐射强迫的影响需要排除这个偏差。两种基于不同试验设计诊断得出的半直接效应分别为0.21 和0.09 W·m-2,存在显著差异。主要原因可能是人为气溶胶影响云辐射强迫的不同机制之间在模式模拟过程中不断地相互交织,不是简单的线性叠加关系。模式诊断得出的Twomey效应不仅包括Twomey效应本身,还包括Twomey效应引起的部分快速调整。总之,利用模式评估分析人为气溶胶气候效应需要注意审查试验设计和诊断方法的合理性。

    Abstract:

    This study illustrates how aerosol affects the top of atmosphere (TOA)radiation flux in the NUIST model,using a hypothetical anthropogenic aerosol forcing determined by Coupled Model Intercomparison Project Phase 6.There are three ways by which anthropogenic aerosol affects TOA radiation flux.First,anthropogenic aerosol affects TOA radiation flux through the changes in aerosol optical properties,known as the aerosol radiative effect.This effect mainly depends on anthropogenic aerosol radiative forcing,and is not related to the Twomey effect.Second,anthropogenic aerosol affects TOA radiation flux through the changes in cloud optical properties,referred to as aerosol effects on cloud radiative forcing.These effects include the Twomey effect and semi-direct effect.Finally,anthropogenic aerosol affects TOA radiation flux via the changes in other optical factors.Compared with the first two ways,this third one is negligible.This study focuses on the second way,and discusses the methods used for estimating anthropogenic aerosol effects.In order to distinguish contributions to aerosol effects on cloud radiative forcing from semi-direct and indirect effects,we added two experiments:Rad and Tmy.The Rad experiment only considers the anthropogenic aerosol optical properties,which the Tmy experiment only considers the anthropogenic aerosol Twomey effect.Including the experiments used in Part 1,there are four experiments in total:Base,Rad,Tmy and Both.The results of the Rad and Base experiments show that anthropogenic aerosol semi-direct effect is estimated at 0.21 W·m-2.Semi-direct effect could also be obtained as the difference between the aerosol effects on cloud radiative forcing from Both and Base experiments (i.e.semi-direct effect and Twomey effect)and the aerosol effects on cloud radiative forcing from Tmy and Base experiments (i.e.Twomey effect).This semi-direct effect is 0.09 W·m-2,significantly less than those from the Bad and Base experiments.The difference between the Tmy and Base experiments shows that the effective radiative forcing (ERF)caused by anthropogenic aerosol Twomey effect is -0.22 W·m-2.Meanwhile,the difference between the Both and Rad experiments shows that the ERF caused by the Twomey effect is -0.30 W·m-2,which is stronger (more negative)than that caused by the difference between the Tmy and Base experiments.It is clear that the assessment results depend on experimental design.One likely reason for this is that aerosol semi-direct and indirect effects interact in a very complex manner,and the assumption of linear superposition is not reasonable.It is worth noting that the diagnosed Twomey effect not only includes the Twomey effect itself,but also cloud-relevant adjustments caused by the Twomey effect.Aerosol could make an obvious impact on quantifying cloud forcing,as aerosol also can scatter and absorb solar radiation.The short wave cloud forcing (SWCF)from Base experiments is -47.54 W·m-2.Under no-aerosol conditions,the SWCF* (i.e.the SWCF calculated as a diagnostic with aerosol scattering and absorption neglected)from the Base experiment is -49.51 W·m-2.The difference caused by the impact of aerosol is 1.98 W·m-2.Compared with the Base experiment,this difference from the Rad experiment is increased by 0.38 W·m-2,because anthropogenic aerosol is considered.In other words,for the same cloud optical properties,the SWCF diagnosed with aerosol optical properties may be shown to increase by~0.38 W·m-2 after considering anthropogenic aerosol optical properties.Due to this obvious positive bias,the aerosol effects on cloud radiative forcing must be estimated from the change in SWCF* (diagnosed with aerosol scattering and absorption neglected),rather than SWCF (diagnosed using the traditional method).

    参考文献
    相似文献
    引证文献
引用本文
分享
文章指标
  • 点击次数:
  • 下载次数:
历史
  • 收稿日期:2018-09-19
  • 最后修改日期:2019-01-14
  • 录用日期:
  • 在线发布日期: 2020-08-31

地址:江苏南京,宁六路219号,南京信息工程大学    邮编:210044

联系电话:025-58731158    E-mail:xbbjb@nuist.edu.cn    QQ交流群号:344646895

大气科学学报 ® 2020 版权所有  技术支持:北京勤云科技发展有限公司