Evaluation of the Influence of Saturation Adjustment with Respect to Ice on Meso-scale Model Simulations for the Case of 22 June, 2002

Abstract

A meso-scale model simulation is sometimes conducted with a saturation adjustment scheme with respect to ice in the upper troposphere. In such a simulation, the super-saturation with respect to ice is not permitted in upper tropospheric clouds, which is contradicting with natural situation.In this study, we evaluate the influence of the application of ice-saturation adjustment to upper tropospheric clouds in a meso-scale model. When the icesaturation adjustment is applied, all of the excess water vapor in upper troposphere is consumed to produce large amount of cloud ice and subsequently snow. Small amount of excess water vapor remain for the depositional growth of snow. Since the fall velocity of snow becomes smaller, the residence time of snow in the atmosphere becomes longer. Consequently, the surface rainfall intensity, on domain-average, becomes slightly smaller through the integration time, compared to the simulation without ice-saturation adjustment.

Evaluation of Cloud Microphysics in JMA-NHM Simulations Using Bin or Bulk Microphysical Schemes through Comparison with Cloud Radar Observations

“…These profiles indicate the comparative characteristics of both microphysics and the hydrometer types that caused the discrepancies between the observed data and the simulations. The overdominance of snow up to the cloud top in the bulk model simulation is consistent with other results using a similar microphysical framework (Hashimoto et al 2007;Eito and Aonashi 2009). The contoured area of the high frequency in the dBZe-height histogram of the bulk model simulation over 4 km is small in spread (Fig.…”

Microphysics Impacts on the Warm Conveyor Belt and Ridge Building of the NAWDEX IOP6 Cyclone

“…However, ice number concentration is several orders smaller than cloud droplets number concentration and supersaturation reached in cold and mixed clouds is far higher than in warm clouds and the assumption of saturation adjustment is no longer applicable (Heymsfield et al 1998;Gettelman et al 2010). When the ice-saturation adjustment is applied, the excess water vapor in the upper troposphere is entirely consumed to produce large amount of cloud ice and subsequently releases large amount of latent heating (Hashimoto et al 2007). By doubling or halving the ice deposition rate in a mesoscale version of the Met Office Unified Model, Forbes and Clark (2003) observed significant impacts on the dynamics of a cyclone and its fronts but, due to the absence of microphysics observations, the authors could not state on the best deposition rate and they did not look at the representation of the PV along the jet stream.…”

NHM-SMAP: Spatially and temporally high resolution non-hydrostatic atmospheric model coupled with detailed snow process model for Greenland Ice Sheet

“…In addition, ice crystal formation in the atmosphere was simulated by using an up-to-date formulation that depends on temperature. Following Hashimoto et al (2007), we did not employ the ice-saturation adjustment scheme and the cumulus parameterization used in the original configuration. The turbulence closure boundary layer scheme was 120 formulated following the improved Mellor-Yamada Level 3 (Nakanishi and Niino, 2006).…”