Simulation of solar tides in the Canadian Climate Centre general circulation model

Abstract

Two 60‐day simulations of the global atmospheric circulation produced by the Canadian Climate Centre general circulation model were analyzed to determine the solar diurnal and semidiurnal variations in the wind, pressure, and precipitation fields. In these simulations the radiative transfer calculations were performed every hour in order to resolve adequately the diurnal cycle. One simulation was for boreal summer, and the other was for winter conditions. The diurnal and semidiurnal surface pressure variations in the model were found to be quite realistic, although somewhat smaller than actually observed. Even some fairly subtle details of the geographical and seasonal variability of the solar tidal pressure oscillation were well simulated. The daily cycle of the wind in the model also appears to be reasonably consistent with the limited observations available. By contrast, the diurnal and semidiurnal variations of precipitation were not successfully simulated by the model. Linear tidal theory calculations were performed with thermal forcings, vertical resolution, and boundary conditions similar to those in the full general circulation model. These calculations allowed an evaluation of the effects of the different numerical approximations in the general circulation model on the simulated tide. One striking result of these linear computations was the indication of a tendency for the effects of the “rigid‐lid” upper boundary condition to compensate for the omission of the thermal tidal forcing above the top level of the model.

A temporal interpolation method to obtain hourly atmospheric surface pressure tides in Reanalysis 1979–1995

“…that is used for the production of the guess field for the stronger tides in the analysis. The rather successful simulation of the tides in numerical weather prediction (NWP) models used in climate mode has been demonstrated by Zwiers and Hamilton [1986].…”

Using Temporal Modes of Rainfall to Evaluate the Performance of a Numerical Weather Prediction Model

“…A few articles have demonstrated or advocated that models of different kinds can be evaluated according to precisely this concept (e.g., Zwiers and Hamilton 1986;Randall et al 1991;Chen et al 1996;Dai et al 1999;Trenberth et al 2003;Dai and Trenberth 2004;Davis et al 2004b), yet such evaluations are uncommon, especially when applied to NWP models.…”

Barometric tides from ECMWF operational analyses

“…Dai and Wang, 1999;Ray, 2001) and from simulations (e.g. Zwiers and Hamilton, 1986). The annual mean S 2 tide, derived from the NASA Goddard Earth Observing System (GEOS-1) reanalysis (Schubert et al, 1993) and from the NCEP-NCAR reanalysis (Kalnay et al, 1996), temporally interpolated by Van den Dool et al (1997), was extensively compared by Ray (2001).…”

“…Tidal harmonic analyses of hourly barometric measurements, taken at a large number of globally distributed stations, can be spatially interpolated (optimally or otherwise) to yield globally gridded fields. More recently, estimates based on general circulation models (Zwiers and Hamilton, 1986;Madden et al, 1998) and on analyses produced by weather centers (Hsu and Hoskins, 1989; Van den Dool et al, 1997;Ray, 2001) have also been examined. The latter products are of special interest because they are based on "optimal" estimates of the state of the atmosphere arrived at through advanced modeling and data assimilation techniques.…”