大气谱模式中质量守恒格式的研究

当前在世界上广泛采用的谱模式，是以地面气压ps取对数作为展谱变量，模式大气总质量不守恒。本文研究这样的问题，提出了以热力学变量比容α代替温度变量T的方法，并以地面气压ps本身作为展谱变量，这样可以保持大气总质量守恒。同时，由于以α作展谱变量，可使重要项气压梯度项为二阶变量组成，截谱后，不会出现混淆误差。计算结果表明，这样改变后，大气总质量保持守恒。同时消除了混淆误差的出现。

Studies on Mass-conservation in Atmospheric Spectral Model

The global spectral models are widely used over the world in the operational numerical weather prediction,atmospheric dynamics and climate simulations.However,there is a problem that nowday spectral models cannot preserve the total atmospheric mass conservation. The problem is caused by using the natural logarithm of surface pressure, Inps, rather than pressure, ps, as one of the spectral represented prognostic variable. Use of p, as prognostic variable does not violate the total mass conervation, but it introduces a much more substantial aliasing erros in the calculation of the pressure gradient. In this paper, we work on the mass-conservation in atmospheric spectral model. Based on the past works, an alternative method of using specific volume,a,as themodynamic variable is proposed.This method, surface pressure, ps, as a prognostic varibable, and it does not cause difficulty in the calculation of the pressure gradient. The computational results show that the forecast quality is slightly improved.