位温方程拉格朗日平流计算方案的改进及其在GRAPES_GFS全球模式的应用

Improvement of Lagrangian Advection Scheme in Potential Temperature Equation and Its Application in GRAPES_GFS Model

GRAPES全球数值预报系统(GRAPES_GFS)个例试验中,模式高层垂直速度在南极大陆上空会出现较大的计算噪音,进而影响模式的积分稳定性,甚至积分中断。对GRAPES_GFS的动力框架以及动力、物理耦合方案进行诊断分析,发现位势温度在拉格朗日上游点上的垂直插值是垂直速度噪音产生的主要原因。2013年7月实际资料试验表明,在位温方程中引入垂直非插值的拉格朗日平流方案,可以减少或消除该计算噪音。使用新的方案后,北半球和热带地区模式预报的整体性能得到了明显提高,8 d预报的全球质量损失较为严重的问题也得到了缓解。

In the case study of GRAPES_GFS,the vertical velocity on the upper level over the Antarctic continent has big computational noise,affecting the integral stability,and even causing the integral interruption.The diagnostic analysis of its dynamical core and physics-dynamics couple scheme indicates that the vertical interpolation of the potential temperature at the Lagrangian departure points is the main source of noise.Monthly case study of July 2013 shows that by introducing the vertical non-interpolated Lagrangian scheme into the thermal equation,this computational noise can be greatly reduced or eliminated.The comprehensive performance in the Northern Hemisphere and tropical region has improved significantly,and the serious loss of mass in 8 d integration process has been significantly alleviated.