| 适用于GRAPES模式C-P边界层方案的设计和实现 |
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| 引用本文： | 陈炯,马占山,苏勇.适用于GRAPES模式C-P边界层方案的设计和实现[J].应用气象学报,2017,28(1):52-61. |
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| 作者姓名： | 陈炯 马占山 苏勇 |
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| 作者单位： | 中国气象局数值预报中心, 北京 100081 |
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| 基金项目： | 资助项目： “十二五”国家科技支撑计划（2012BAC22B02），国家自然科学基金项目（41375051，41105067，41305090），公益性行业（气象）科研专项（GYHY201406005），中国气象局数值预报GRAPES发展专项(GRAPES FZZX 2016 02) |
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| 摘 要： | 基于K廓线闭合方案，通过考虑不稳定边界层和稳定边界层中热量交换系数在半层上求取及下边界条件的设置，将温湿倾向在整层上直接计算，设计了Charney-Phillips跳点（简称C-P跳点）的边界层方案，使之与GRAPES全球模式的C-P跳点相协调，解决了Lorenz跳点物理过程与C-P跳点动力框架耦合时插值造成的不协调问题，同时避免了耦合时反复插值造成的误差，提高了边界层物理过程参数化方案及其反馈的准确性和合理性。试验表明:C-P跳点边界层方案因为避免了温度和湿度在垂直方向上的插值，消除了温湿变量在垂直方向上的锯齿状抖动，使温湿廓线分布更合理，减小了模式预报误差，形势场的预报效果也得到一定改善。C-P边界层方案的应用提升了GRAPES全球模式的总体预报性能。
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| 关 键 词： | GRAPES模式 边界层过程 C-P跳点 Lorenz跳点 |
| 收稿时间： | 2106/3/22 0:00:00 |
| 修稿时间： | 2016/10/12 0:00:00 |
Boundary Layer Coupling to Charney Phillips Vertical Grid in GRAPES Model |
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| Chen Jiong,Ma Zhanshan and Su Yong.Boundary Layer Coupling to Charney Phillips Vertical Grid in GRAPES Model[J].Quarterly Journal of Applied Meteorology,2017,28(1):52-61. |
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| Authors: | Chen Jiong Ma Zhanshan and Su Yong |
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| Institution: | Numerical Weather Prediction Center of CMA, Beijing 100081 |
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| Abstract: | It is an important challenge in numerical weather and climate prediction to obtain accurate coupling between physical parameterization and high resolution dynamic framework. Increased resolution in models and the use of large time-steps in semi-Langrangian advection stress the need for an equally accurate computation in time of the corresponding physical parameterizations and the physics-dynamics coupling on the temporal aspects. Physics-dynamics coupling on spatial aspects also plays a very important role on the accuracy of model predictions, for there is a choice for how to vertically arrange the predicted variables, namely, the Lorenz and Charney-Phillips grids.The physics-dynamics coupling on spatial aspects in GRAPES model is studied. As the Charney-Philips grid is used, the horizontal velocity is staggered relative to potential temperature, which means potential temperature and water substances are calculated at full levels, while horizontal velocity is calculated at half levels. In Lorenz physics scheme, all variables are set at half levels and the correspondent tendencies are estimated at half levels. The interpolation has to be used between full and half levels in physics-dynamics coupling before and after physics scheme package is called. The interpolation error is unavoidable and an unexpected zigzag noise appears because of the second-order difference in PBL (planetary boundary layer) scheme.In C-P PBL scheme, the momentum diffusivity KM is required at full levels and the heat diffusivity KH is required at half levels. It is easy to compute KM and KH in unstable PBL because KM and KH depend on the PBL height and surface variables. For local scheme in stable PBL and free convective atmosphere, diffusivities are functions of local Richardson number which has relation with both potential temperature and horizontal velocity. Here potential temperature gradient is averaged so that Richardson number is calculated at full levels. KM can be calculated at the full level and KH can be averaged at the half level. The boundary condition is given by the surface flux according to the constant flux layer. C-P PBL parameterization is developed to assure the accurate coupling of PBL physics and vertical Charney-Phillips grid.Improvements are detected using C-P PBL parameterization spatial physics-dynamics coupling in GRAPES_GFS model. The zigzag noise of temperature and moisture in PBL is removed and the correspondent profiles appear to be smooth with C-P PBL parameterization. The accuracy of PBL and dynamics coupling is improved, and an overall enhancement is found in the forecast of height and temperature. |
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| Keywords: | GRAPES model planetary boundary layer Charney Phillips grid Lorenz grid |
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