结合“海棠”台风(2005)定量分析非绝热加热对湿Q矢量诊断能力的影响

Quantitative analysis of the effect of diabatic heating on diagnostic ability of moist Q vector based on typhoon Haitang(2005)

湿Q矢量最大特点就是考虑了非绝热加热作用,各种湿Q矢量差异也主要表现在对非绝热加热计算处理方案的不同。因此,通过比较分析非绝热加热作用,可揭示出不同湿Q矢量之间诊断能力的差异。2005年第5号登陆台风"海棠"在7月19日08时—20日08时,给福建省东北部及浙江省造成大范围暴雨。WRF模式成功模拟出此次台风暴雨过程。文章将结合"海棠"台风(2005)登陆台风暴雨过程,利用WRF模式模拟输出的气象要素,通过计算降水场,定量分析了非绝热加热作用及其对湿Q矢量诊断能力的影响。结果表明:(1)对于仅包括大尺度凝结加热的非绝热加热作用H_1及包括了潜热加热(大尺度凝结加热和对流凝结加热)、感热加热和辐射加热的非绝热加热作用H_2来讲,局地变化项的强迫作用较垂直平流项、水平平流项的强迫作用约小1—2个量级,可以忽略不计,垂直平流项的强迫作用是主要成分,对于水平平流项来讲,尽管其强迫作用明显小于垂直平流项的强迫作用,但也明显大于局地变化项的强迫作用,考虑其将更有利于充分反映H_1、H_2的强迫作用。对于包括非均匀饱和大气中潜热加热的H_3来讲,水平平流项与垂直平流项的强迫作用相当,均为主要成分,而局地变化项的强迫作用为次要成分且不容忽视,对其考虑将有助于全面描述H_3的强迫作用。(2)非绝热加热作用H_1、H_2以及H_3强迫产生的24 h累积降水场具有相似的水平分布特征,三者强迫产生的逐时雨量随时间演变特征也非常相似,这表明水汽凝结潜热是非绝热加热作用的主要成分。(3)进一步结合模拟降水场分析表明,相对于H_1强迫产生的降水场来讲,H_2与H_3强迫产生的降水场更接近模拟结果,这揭示出包含H_2的湿Q矢量与包含H_3的湿Q矢量诊断能力相近,且对降水反映能力较包含H_1的湿Q矢量诊断能力强。(4)不同湿Q矢量各自有其自身诊断特点,根据不同研究目的的需要,可有针对性的选取相应的湿Q矢量来作为研究工具。如需要具体、细致分析水汽潜热的强迫作用,可以选用包含H_1、H_3的湿Q矢量,如仅需考虑总的湿Q矢量强迫作用,则可以直接选用包含H_2的湿矢量。

Considering diabatic heating is the most notable feature of moist Q vector,and the difference among moist Q vectors is caused by differing conductional methods of diabatic heating.Therefore,the comparison and analysis of diabatic heating can display the difference among diagnostic abilities of moist vectors.Typhoon Haitang landing Fujian Province from 08：00 BST 19 July to 08：00 BST 20 July in 2005,gives rise to wide range heavy rainfall in northeast of Fujiang Province and most of Zhejiang Province.The rainfall process is simulated successfully by the Weather Research and Forecasting（WRF） model.Combining a torrential rainfall process associated with landfalling Typhoon Haitang（2005）,using the simulated outputs from the WRF model,and by calculating precipitation field,the role of diabatic heating and its influence on diagnostic ability of moist vector are analyzed quantitatively.The results are as follows： （1） As far as diabatic heating H_1 only including large-scale condensational heating and diabatic heating H_2 including latent heating （large-scale condensational heating and convective condensational heating）,sensible heating and radiation heating are concerned,the forcing role of local variation term is about 1—2 orders smaller than the counterparts of vertical advective term and horizontal advective term,which can be omitted,the forcing role of vertical advective term is the predominant component,and the forcing role of horizontal advective term is smaller than the counterpart of the vertical advective term evidently while larger than the counterpart of the local variative term obviously,which is contributed to depict the forcing roles of H_1 and H_2 completely.To diabatic heating H_3 only including latent heating in the non-uniformly saturated moist atmosphere,the forcing role of horizontal advective term is basically equal to the counterpart of vertical advective term,which are the primary components of H_3,and the forcing role of local variative term is secondary whereas it can not be omitted,which is contributed to portray the forcing role of H_3 fully.（2） The 24-h accumulated rain fields forced by the diabatic heating H_1,H_2,and H_3 have similar horizontal distribution characteristics,and the hourly cumulative rainfall amounts forced by the three parts have similar time evolution features,which both disclose that vapor condensational latent heat plays the main role in the diabatic heating.（3） On the basis of the simulated precipitation field,the analysis shows that the precipitation fields forced by H_2 and H_3 are more close to the simulated precipitation field than the counterpart forced by H_1,which displays that the diagnostic abilities between the moist Q vector including H_2 and the moist Q vector including H_3 are almost equivalent,and their reflecting abilities to precipitation are stronger than the counterpart of the moist Q vector including H_1.（4） Each moist Q vector has its diagnostic characteristic, hence,according to the requirement of the research object,the corresponding moist Q vector can be chosen as the diagnostic tool with a clear aim.If the forcing role of vapor latent heating is needed to be considered carefully,the moist Q vector including H_1 or H_3 can be chosen.If only the total forcing role of moist Q vector is considered,the moist Q vector including H_2 can be chosen.