关键词: GRAPES全球模式, 背景误差功率谱, 水平相关特征尺度

Abstract:

Based on GRAPES-Global model forecast data in one month, the statistics of  background error covariance of GRAPES-Global model was done by using NMC method. The spectrum curve and horizontal correlation characteristic scale of background error covariance were calculated and analyzed. Compared the results of GRAPES with ECMWF, the rotational kinetic energy spectrum, divergent kinetic energy spectrum, total kinetic energy spectrum and geopotential height power spectrum increased gradually when wavenumber ranged from 1 to 7, and they reached maximum when wavenumber ranged from 7 to 14, then decreased slowly with  increasing of wavenumber. The calculation values of GRAPES and ECMWF were also very close when wavenumber was less than 60. Meanwhile, the horizontal correlation characteristic scales were calculated separately by using spectral method and grid method, and results of both methods show that the horizontal correlation characteristic scales of background error increased with height and decreased with wavenumber, but calculation values of spectral method were larger than those of grid method.

Key words: GRAPES-Global model, background error power spectrum, horizontal correlation characteristic scale