Rainfall parameterization in an off‐line chemical transport model
Rainfall parameterization in an off‐line chemical transport model
复制标题
离线化学品传输模型中的降雨参数化
DOI：
10.1002/asl.68
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发表时间：
2004
影响因子：
3
通讯作者：
A. Koussis
中科院分区：
文献类型：
--
作者：
C. Giannakopoulos;P. Good;K. Law;K.;E. Akylas;A. Koussis
本文提出了在三维离线化学输运模型中模拟大规模降水和对流降水的技术。提出了相对简单的公式，将产生有意义的降雨率，用于化学物质的湿沉降，而不会影响模型的计算效率。由于从现有气象分析中获得的湿度和温度剖面太稳定，无法产生任何降雨，因此我们通过平流破坏它们的稳定性。该技术仅针对大范围降雨进行了测试，但也可以应用于对流降雨，以减少降雨的不均匀性并改善与观测的比较。对于离线模型，TOMCAT 似乎出人意料地很好地捕捉到了观测气候学所见证的降雨量的全球分布模式。它在捕捉干燥的亚热带地区和潮湿的亚洲季风季节以及热带地区随季节变化的降雨量减轻方面表现良好。然而，它低估了夏季和南纬30°以南大陆全年的降水量。如果我们也将平流技术应用于对流降雨，这些缺点就可以得到改善。此外，我们可以从气象分析中获得表面降水总量，然后使用我们的模型导出的网格点凝结率垂直缩放这些量。版权所有 © 2004 英国皇家气象学会
In this paper, techniques for the modelling of both large‐scale and convective precipitation in a three‐dimensional off‐line chemical transport model are proposed. Relatively simple formulations are proposed that will yield meaningful rainfall rates to be used for the wet deposition of chemical species without compromising the computational efficiency of the model. As the profiles of humidity and temperature obtained from available meteorological analyses are too stable to produce any rainfall, we destabilize them through advection. This technique has been tested here for the large‐scale rainfall only, but can also be applied to the convective rainfall to make it less spotty and improve the comparison with observations. For an off‐line model, TOMCAT seems to capture surprisingly well the global distribution pattern of the rainfall as witnessed by observational climatologies. It performs well in capturing the dry subtropical regions and the wet Asian monsoon season as well as the mitigation of rains in the tropics with the change of season. However, it underestimates precipitation in the continents in the summer and south of 30 °S all year round. These shortcomings could be improved if we apply the advection technique to the convective rainfall as well. In addition, we could obtain the surface precipitation totals from the meteorological analyses and subsequently scale these amounts vertically using our model‐derived grid point condensation rate. Copyright © 2004 Royal Meteorological Society