章超,王震,杨军,孙继明,郜海阳,崔生成. 2016. 三维有云大气辐射变温率数值模拟研究——邻云辐射效应[J]. 气象学报, 74(4):598-612, doi:10.11676/qxxb2016.040
三维有云大气辐射变温率数值模拟研究——邻云辐射效应
A numerical study of radiative heating rate in the three-dimensional cloudy atmosphere: Adjacent-cloud-induced radiative effects
投稿时间:2016-03-03  修订日期:2016-04-16
DOI:10.11676/qxxb2016.040
中文关键词:  三维云场  辐射变温率  长波辐射保温  散射增温  遮蔽降温
英文关键词:Three-dimensional cloudy atmosphere  Radiative heating rate  Longwave radiative warming  Scattering-induced warming  Shadowing-induced cooling
基金项目:国家自然科学基金青年科学基金项目(41305032、41304124)。
作者单位E-mail
章超 中国气象局气溶胶-云-降水重点开放实验室, 南京信息工程大学大气物理学院, 南京, 210044  
王震 中国气象局气溶胶-云-降水重点开放实验室, 南京信息工程大学大气物理学院, 南京, 210044  
杨军 中国气象局气溶胶-云-降水重点开放实验室, 南京信息工程大学大气物理学院, 南京, 210044 jyang@nuist.edu.cn 
孙继明 中国科学院大气物理研究所, 北京, 100029  
郜海阳 中国气象局气溶胶-云-降水重点开放实验室, 南京信息工程大学大气物理学院, 南京, 210044  
崔生成 中国科学院安徽光学精密机械研究所大气成分与光学重点实验室, 合肥, 230031  
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中文摘要:
      大气数值模式普遍采用一维辐射传输模型,无法表征有云大气中的三维辐射传输过程,从而影响数值模拟乃至数值天气预报的准确性。为评估这种不确定性,研究了水平云体间的三维辐射相互作用及其改变云体热力结构的规律,力求为改进数值模式辐射计算方案提供理论依据。选取I3RC PhaseⅡ的典型积云场和层积云场作为试验对象,将云场中心区域云体视为目标云体,周围云体为邻近云体,采用宽带三维辐射传输模式SHDOM模拟长波和短波辐射变温率的空间分布,定量阐明邻近云体对目标云体热力结构的影响。结果表明,邻云在长波区域对目标云体主要起辐射保温的作用,目标云体增温区域集中于邻云一侧的云体表面层,增温强度与云覆盖率和云间距离倒数成正比,最高可达3.08 K/h,云体增温的厚度与目标云体液态水含量成反比;在短波区域,邻云同时起散射增温和遮蔽降温的作用,太阳垂直入射时,散射增温效应较弱,变温率空间差异小;当太阳天顶角增大后,遮蔽降温效应逐步起主导作用,造成目标云体被邻云遮挡一侧的表面层明显降温,峰值可达-1.72 K/h,数值上甚至超过邻云长波增温效应。总之,邻近云体可以明显改变目标云体的变温率空间分布,引入三维邻云辐射效应对改进大气数值模式辐射计算方案具有重要意义。
英文摘要:
      One-dimensional radiative transfer model has been widely used in atmospheric numerical studies. However, the one-dimensional model neglects the radiation transport process in the three-dimensional cloudy atmosphere and thus produces inaccurate numerical simulations and weather forecasts. In order to address uncertainties in the one-dimensional radiative transfer model and optimize the radiation parameterization in numerical weather forecast system, effects of three-dimensional radiation interaction among clouds and their impacts on the thermodynamic structure of clouds are studied. I3RC Ⅱ cumulus and stratocumulus fields are selected for the present study, and their central areas are taken as the target domain while the surrounding areas are treated as the adjacent domain. Spatial distributions of shortwave and longwave radiative heating rates are simulated by the broadband three-dimensional radiative transfer model SHDOM to illustrate the impact of the adjacent-cloud on the thermodynamic structure of the target-cloud. Simulation results show that the adjacent-cloud imposes longwave radiative warming effects on the entire target domain. The warming zone is mainly located in the surface layer of the cloud, the depth of which is negatively correlated with the liquid water content; the warming rate is proportional to cloud coverage and the reciprocal of the distance between the target and adjacent clouds, and its maximum value is 3.08 K/h. For shortwave bands, the adjacent-cloud has both scattering-induced warming effects and shadowing-induced cooling effects for the target-cloud. With a small solar zenith angle, warming effects are dominant although they are quite weak with a small spatial inhomogeneity. As the solar zenith angle increases, cooling effects become more important and cause significant temperature reductions (the maximum reduction is 1.72 K/h) in the surface layer of the target-cloud on the side sheltered by the adjacent-cloud. The shading effects may even exceed the longwave radiative warming effects. In conclusion, the adjacent-clouds could greatly change the local heating rate of the target-clouds. Therefore, it is crucial to consider the three-dimensional radiative effects in the numerical weather forecast system to improve the radiation parameterization.
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