计算参考气压的一种新方案

本文根据位相当温度与相当温度以及气压之间的内在关系指出,在气压给定的情况下,位相当温度与相当温度之间存在线性关系;而当相当温度确定时,位相当温度与气压的关系是非线性的。进而提出在第一次调整中应当先线性内插得到对应的相当温度、再由三者关系的另一种表达式计算对应的气压的新方案。同时也指出,由于时间平均可能造成某些θ_e。无对应参考气压P_r,在考虑区域问题时,第二次调整宜用空间平均,以及为了避免再出现不稳定层结,宜在计算程序中增加一次类似于第一次的调整。文章最后通过实例对比,证实了新方案在客观地确定参考气压、准确地计算湿有效位能等方面都比原方案有较明显的改进。 

A NEW SCHEME FOR CALCULATING THE FIDUCIAL PRESSURE

Based on a relationship among potential equivalent temperature,equivalent temperature and pressure,a linear link is shown to exist between potential equi -valent temperature and equivalent temperature at a given pressure while a nonlinear link is found between potential equivalent temperature and pressure at a given equivalent temperature.A new scheme for calculating the fiducial pressure is then proposed According to it,the T_eη which corresponds to the θ_eη can be interpolated linearly during the first adjustment and then the P_η corresponding to θ_eη can be calculated by another form of the same relation:P_η=EXP(LN(1000)-(C_P/R_d)*LN(θ_eη/T_eη)).When areal question is considered,it would be best to take spatial mean during the second adjustment,for some higher or lower θ_e without corresponding to P_r may appear in using the temporal mean.The third adjustment,similar to the first one,must be added if there is unstable stratification after the first two adjustments.Compared with the previous version,of the scheme it exhibits significant advantages in determining the fiducial pressure objectively and calculating the wet available energy accurately.