Towards a dry‐mass conserving hydrostatic global spectral dynamical core in a general moist atmosphere

Abstract

The aim of this article is to develop a dry‐mass conserving hydrostatic global spectral dynamical core in a general moist atmosphere, which can be regarded as an alternative, improved version of that used in the current Integrated Forecast System (IFS) of the European Centre for Medium‐Range Weather Forecasts (ECMWF). In contrast to the original IFS‐like core, the dry‐mass vertical coordinate is employed and the mass continuity equation is expressed in terms of the dry air density, which ensures the inherent conservation of dry air mass. Meanwhile, the thermodynamic equation is reformulated with a modified temperature variable and the formula used to compute the full pressure vertical velocity is derived rigorously. To assess the performance of this new core, an idealized tropical cyclone (TC) test is conducted. Simulation results from both the new core and the original IFS‐like dynamical core are presented and compared. The results show that the TC‐like storm produced by the new dynamical core is more intense, more compact and more concentric, and is thus much more in line with previous results from other global models. In this new dynamical core, the diagnosed full pressure vertical velocity is decomposed into four components, of which the first component, the dry hydrostatic pressure vertical velocity, dominates. Sensitivity experiments imply that despite their small numerical value the other three components should not be neglected, especially for medium‐range forecasts.

An implementation of single‐precision fast spherical harmonic transform in Yin–He global spectral model

“…It is further seen that the introduction of a mass conservation fixer (Rasch and Williamson, 1990) does not significantly improve the anomaly correlation coefficients. This may be related to dry‐mass conserving the hydrostatic global spectral dynamical kernel (Peng et al ., 2019; 2020) used in YHGSM. The results shown in Figures 7 and 8 are consistent with the summary plots Figures 5 and 6 (i.e.…”

NWPP-EDH: Numerical weather prediction products evaporation duct regional prediction model

“…The YHGSM (Yang et al, 2015;Yin et al, 2018;Peng et al, 2020;Yin et al, 2021) is a numerical weather forecast model developed by the National University of Defense and Technology. Its products data have a relatively stable system error, and the data are provided in a data set for machine learning research in meteorology.…”

Effect of Flow-Dependent Unbalanced Background Error Variances on Tropical Cyclone Forecasting

“…The model that matches the assimilation system used in the experiment is the Yin-He Global Spectral Model (YHGSM), which is a global NWP model developed by the College of Meteorology and Oceanography, National University of Defense Technology. The dynamical core of the YHGSM satisfies the dry-mass conservation constraint proposed by Peng, et al [24]. The time discretization adopts the semi-implicit semi-Lagrangian scheme, and the spatial discretization adopts the spherical harmonic functions expansion (horizontal) and the finite-element method (vertical).…”