摘要
云在全球辐射平衡和气候变化中起着重要作用.气候模式中的积云参数化方案影响着降水、季节内震荡和气候等的数值模拟研究.夹卷率是积云参数化中一个重要的物理量,影响着热量、动能和水汽的垂直输送.在过去几十年时间里,为了准确地估算夹卷率,科学家们投入了大量的精力,但目前的夹卷率估算仍然存在很大的不确定性.
This paper focuses on the variability in entrainment rate in individual cumulus clouds using the entrainment rate estimated on the scale of 5 m in 186 shallow cumulus clouds from eight aircraft flights, using in situ observations from the RACORO field campaign(the routine atmospheric radiation measurement aerial facility clouds with low optical water depths optical radiative observations) over the atmospheric radiation measurement Southern Great Plains site, USA. The result shows that the mean entrainment rate of all the 186 clouds systematically decreases from the cloud edge to the cloud center. Further analysis of the fluctuation of entrainment rate shows that the probability density function of entrainment rate in each flight can be fitted by the lognormal, gamma, or Weibull distributions virtually equally well, with the Weibull distribution being the best. The parameter ‘‘standard deviation'' in the lognormal distribution is weakly negatively correlated, and the other parameters in the three distributions are positively correlated with relative humidity in the entrained dry air and dilution effect, respectively.Entrainment rate is negatively correlated with droplet concentration, droplet size, and liquid water content, but positively correlated with relative dispersion. The effect of entrainment rate on the spectral shape of cloud droplet size distribution is examined and linked to the systems theory on the cloud droplet size distribution.
出处
《科学通报》
EI
CAS
CSCD
北大核心
2015年第19期1851-1851,共1页
Chinese Science Bulletin
基金
国家自然科学基金(41305120
41030962)
江苏省环保科研课题(2013042)
江苏省自然科学基金(BK20130988)
教育部高等学校博士学科点专项科研基金(20133228120002)
江苏省高校自然科学基金(13KJB170014)
公益性行业(气象)科研专项(GYHY 201406007)
中国科学院大气物理研究所大气科学和地球流体力学数值模拟国家重点实验室开放课题
气象灾害教育部重点实验室开放课题(KLME1305)
青蓝工程
江苏高校优势学科建设工程
美国能源部地球模拟研究计划(ESM)中FASTER项目
大气系统研究项目(ASR)资助
