MM5模式水平扩散项的改进及其对陕西“8.28”暴雨模拟的影响

基金项目: 国家自然科学基金(40475022);科技部科研院所社会公益专项资金重点项目(2002DIA20013)共同资助

SIMULATING THE "AUGUST 28" RAINSTORM THROUGH IMPROVING THE HORIZONTAL DIFFUSION IN MM5

1.
National Meteorological Center, Beijing 100081, China
2.
State Key Laboratory of Severe Weather, Chinese Academy of Meteorological sciences, Beijing 100081, China

摘要: 在数值预报发展的过程中,我们通常把水平扩散项当作滤波器用来光滑或是过滤掉模式积分过程中所产生的毫无天气意义的并会引起非线性计算不稳定的所谓计算噪音或"超短波",从而达到阻尼虚假短波以及抑制非线性计算不稳定的目的,但这仅仅只是从计算数学或计算物理的角度来考虑,并不能真正反映扩散的物理本质。本文尝试运用热力学第二定律的思想对MM5模式中的水平扩散项进行改造,以便更好地消除原模式中的扩散项所导致的Gibbs振荡现象。通过对陕西2003年8月28日暴雨的数值模拟表明,改进后的MM5模式的输出量(如相对湿度、温度、速度)的相关系数以及均方根误差均有明显的改进。
- 热力学第二定律 /
- 水平扩散 /
- Gibbs振荡
Abstract: Horizontal diffusion is generally included in the governing equations of numerical weather prediction models for computational rather than physical consideration and the horizontal diffusion scheme of MM5 will bring spatial oscillation,known as Gibbs phenomenon,which could be avoided by incorporating the second law of thermodynamics into MM5.In this paper the improvement of MM5 by the physics-based diffusion scheme is presented using the case of the August 28,2003 rainstorm in Shanxi.
- horizontal diffusion /
- the second law of thermodynamics /
- Gibbs phenomenon

[1]	GORDON C T,Stern W F.A description of the GFDL global spectral model[J].Mon Wea Rev,1982,110(7):625-644.
[2]	WONG V C,LILLY D K.A comparison of two dynamic subgrid closure method for turbulent thermal convection[J].Phys Fluids,1994,6(2):1 016-1 023.
[3]	廖洞贤.数值天气预报原理及应用[M].北京:气象出版社,1988:118-124.
[4]	JAKIMOW G,YAKIMIW E,ROBERT A.An implicit formulation for horizontal diffusion in gridpoint models[J].Mon Wea Rev,1992,120(1):124-130.
[5]	钱维宏.大气中的耗散结构与对流运动[J].大气科学,1992,16(1):84-91.
[6]	柳崇健.大气耗散结构理论[M].北京:气象出版社,1988:101-129.
[7]	SMAGORINSKY,MANABE M,et al.Numerical results from a nine-level general circulation model of the atmosphere[J].Mon Wea Rev,1965,93(12):727-767.
[8]	XUE M.High-order monotonic numerical diffusion and smoothing[J].Mon Wea Rev,2000,128(8):2 853-2 864.
[9]	闫敬华,薛纪善."5.24"华南中尺度暴雨系统结构的数值模拟分析[J].热带气象学报,2002,18(4):302-308.
[10]	杨静,王鹏云,李兴荣."99.6"梅雨锋暴雨云和降水物理过程的中尺度数值模拟[J].热带气象学报,2003,19(2):203-212.