青藏高原、东亚季风区、西北太平洋地区云系结构及相联加热机制的对比分析

应用7年(2006年5月18日—2013年5月18日)的CloudSat卫星观测资料，对比分析了青藏高原、东亚季风区、西北太平洋地区云发生频率的特征，并利用欧洲中心再分析资料，计算了三个地区的视热源、视水汽汇Q₁、Q₂，分析探讨了三个地区与云发生频率相联系的加热机制。结果表明:青藏高原、东亚季风区、西北太平洋地区云的发生频率分别为35%、22%、27%，其中:青藏高原和东亚季风区的低云频率最大，中云次之；西北太平洋地区的高云和低云的频率大，分别为19%和16%。具体云型来看，青藏高原多高层云、雨层云；东亚季风区多高层云和卷云，夏季深对流云频率增大明显；西北太平洋地区多卷云、深对流云和高层云。三个地区视水汽汇Q₂的垂直分布特征及季节变化与云发生频率对应较好，青藏高原的低云(雨层云)、中云(高层云)形成过程中，凝结释放潜热，加热大气；东亚季风区低云(深对流云)、中云(高层云)对加热大气贡献大；西北太平洋地区大气的主要加热机制是深对流云形成过程中凝结释放潜热以及湿静能涡旋垂直输送。 

A COMPARATIVE ANALYSIS OF CLOUD STRUCTURE AND ASSOCIATED HEATING MECHANISM IN THE TIBETAN PLATEAU,THE EAST ASIAN MONSOON REGION AND THE NORTHWESTERN PACIFIC

Based on 7-year (May 18, 2006~May 18, 2013) CloudSat observations, characteristics of occurrence frequencies of clouds in the Tibetan Plateau, the East Asian monsoon region and the Northwestern Pacific are compared. Moreover, apparent heat source (Q₁) and apparent moisture sink (Q₂) are calculated for the same period by making use of the ERA-Interim reanalysis dataset. With the heat sources (Q₁) and moisture sinks (Q₂) profiles over the three regions, heating mechanisms associated with cloud frequency are discussed. Results show that the frequency of cloud occurrences in the Tibetan Plateau (TP), the East Asian monsoon region (EA) and the Northwestern Pacific (WNP) is 35%, 22% and 27%, respectively. Among low, middle and high clouds, the highest frequency in the TP and the EA is low clouds, followed by middle clouds. In the NWP the frequency of high and low cloud is higher than that of middle clouds, close to 19% and 16%, respectively. In terms of the type of cloud and annual mean, there is a large amount of Nimbostratus and Altostratus over the TP and much cirrus in the EA with significantly frequent deep convective clouds in summer. On the other hand, cirrus, deep convective clouds and Altostratus are dominating in the WNP. The vertical distribution and seasonal variation of moisture sink (Q₂) are well corresponding to cloud frequency in the three regions. Over the TP, the atmospheric heating by condensing water vapor and releasing latent heat is mainly due to low clouds (Nimbostratus) and middle clouds (Altostratus) formation. In the EA, low clouds (deep convection) and middle clouds (Altostratus) are making much more contribution to the heating than the others. In the WNP, atmospheric heating largely comes from deep convective cloud which is condensing water vapor and releasing latent heat with vertical transport of eddy moist static energy.