Application of a global nonhydrostatic model with a stretched-grid system to regional aerosol simulations around Japan

Abstract

Abstract. An aerosol-coupled global nonhydrostatic model with a stretched-grid system has been developed. Circulations over the global and target domains are simulated with a single model, which includes fine meshes covering the target region to calculate meso-scale circulations. The stretched global model involves lower computational costs to simulate atmospheric aerosols with fine horizontal resolutions compared with a global uniform nonhydrostatic model, whereas it may require higher computational costs compared with the general regional models, because the stretched-grid system calculates inside and outside the target domain. As opposed to general regional models, the stretched-grid system requires neither a nesting technique nor lateral boundary conditions. In this study, we developed a new-type regional model for the simulation of aerosols over Japan, especially in the Kanto areas surrounding Tokyo, with a maximum horizontal resolution of approximately 10 km. This model usually reproduces temporal variations and their averages of the observed weather around Japan. This model generally reproduces monthly mean distributions of the observed sulfate and SO 2 over East Asia, with high correlations (R > 0.6), but the underestimation of the simulated concentrations by 40 % (sulfate) and 50 % (SO 2 ). Their underestimation of the simulated sulfate and SO 2 concentrations over East Asia are strongly affected by their underestimation in China and possibly by the uncertainty of the simulated precipitation around Japan. In the Kanto area, this model succeeds in simulating the wind patterns and the diurnal transitions around the center of the Kanto area, although it is inadequate to simulate the wind patterns and the diurnal transitions at some sites located at the edge of the Kanto area and surrounded on three sides by mountains, e.g., Maebashi, mainly due to the insufficient horizontal resolution. This model also generally reproduces both diurnal and synoptic variations of the observed and/or a regional aerosol-transport model, WRF-CMAQ, simulated EC, sulfate, and SO 2 concentrations in the Kanto area, especially with their high correlation (R > 0.5) at Komae/Tokyo. Although the aerosol module used in this study is relatively simplified compared to the general regional aerosol models, this study reveals that our proposed model with the stretchedgrid system can be applicable for the regional aerosol simulation.Published by Copernicus Publications on behalf of the European Geosciences Union. D. Goto et al.: Application of a global nonhydrostatic model to regional aerosol simulations around Japan

A 4D-Var inversion system based on the icosahedral grid model (NICAM-TM 4D-Var v1.0) – Part 1: Offline forward and adjoint transport models

“…If we limit the analysis period to a short time, a global high-resolution inversion would be feasible as long as sufficient data storage capacity is available. Furthermore, regional high-resolution inversions would also be possible with the grid stretching technique (Tomita, 2008;Goto et al, 2015). It is expected that the system developed in this study and in the accompanying paper can exploit new observations and open up new avenues for GHG inversions.…”

On the spatio-temporal representativeness of observations

“…Briefly, the models WRF-Chem (Grell et al, 2005;Fast et al, 2006), EMEP/MSC-W (Simpson et al, 2012) and NICAM-SPRINTARS (see Goto et al, 2015, and references therein) were used to simulate common observables (aerosol optical thickness, extinction, PM 2.5 , black carbon (BC) mass concentration, number densities and cloud condensation nuclei) on a 10 km grid with hourly resolution (snapshots, only precipitation data are accumulated). All models nudged wind speeds to reanalysis meteorology and used emissions with diurnal profiles where relevant.…”

Simulating Long Range Transport of Radioactive Aerosols Using a Global Aerosol Transport Model

“…It is a seamless global-to-regional model which does not involve nesting technique and boundary conditions from global model (Goto et al, 2015). More details of the code development and its capabilities are found in various literature (Satoh, 2002;Tomita et al, 2002;Tomita et al, 2005;Satoh et al, 2008).…”

“…NICAM-SPRINTARS was previously used for simulating effects of aerosols on atmospheric pollution and climate system at global as well as regional scale (Dai et al, 2014;Goto, 2014;Goto et al, 2015). The important features and advantages of this model for aerosol simulations are highlighted by Goto et al (2015).…”