Changes in the Baiu Frontal Activity in the Future Climate Simulated by Super-High-Resolution Global and Cloud-Resolving Regional Climate Models

Self Cite

139

123

A global warming projection experiment was conducted on the Earth Simulator using a very high horizontal resolution atmospheric general circulation model, with 20-km grid size (the 20-km model). Such high horizontal resolution in a global climate model is unprecedented for a global warming projection. Experiments using the 20-km model were conducted by adopting the time-slice method, in which future changes in sea surface temperature (SST) were predicted by an atmosphere-ocean general circulation model (AOGCM) called MRI-CGCM2.3. The A1B emission scenario, proposed by the Intergovernmental Panel on Climate Change (IPCC), was assumed in the experiment.The model reproduces a realistic Baiu rain band under the present-day climate conditions in terms of geographical distribution and northward seasonal march. Experiments of the dependency of the horizontal resolution on the reproducibility of the Baiu rain band have revealed that the 20-km model generally exhibits higher performance than a model with a lower horizontal resolution. The future climate simulation shows that precipitation, and its intensity increases over the Yangtze River valley of China, the East China Sea, Western Japan, and the ocean to the south of the Japan archipelago. Conversely, precipitation and its intensity decrease over the Korean peninsula and Northern Japan. The termination of the Baiu season tends to be delayed until August.The future precipitation change is mainly attributable to the change in the horizontal transport of water vapor flux and its convergence associated with the intensification of a subtropical high. This can be interpreted as an atmospheric response to the El Niñ o condition of the ocean. The change in the wind field mainly contributes to the change in the water vapor flux in the case of the Baiu rain band.

Section: Precipitationmentioning

confidence: 97%

“…1d). Yasunaga et al (2006) attributed the intensification and stagnation of the Ogasawara high in the future climate, to the concentration of active convection over this equatorial higher SST region. This higher-SST region might lock the position of the Ogasawara high, and hinder the high from moving northward.…”

Section: Precipitationmentioning

confidence: 99%

Change of Baiu Rain Band in Global Warming Projection by an Atmospheric General Circulation Model with a 20-km Grid Size

Kusunoki

Yoshimura

et al. 2006

Self Cite

139

123

“…Mizuta et al (2006) conducted a numerical simulation using a GCM with a 20 km mesh called MRI-GCM TL959L60 that was developed by the Meteorological Research Institute, Japan Meteoro logical Agency (hereafter, MRI-GCM). The simulation yielded a significantly improved representation of precipitation including specific phenomena such as the Baiu (Yasunaga et al 2006;Kusunoki et al 2006), the Asian monsoon (Yatagai et al 2005;Mizuta et al 2006), and the tropical cyclone . Mizuta et al (2006) also indicated that the model performance (e.g., the global distribution of precipitation and surface temperature) was drastically improved by the MRI-GCM, which can simulate local wind circulation.…”

mentioning

confidence: 99%

Assessment of the Diurnal Cycle of Precipitation over the Maritime Continent Simulated by a 20 km Mesh GCM Using TRMM PR Data

Hara

Yoshikane

Takahashi

et al. 2009

Self Cite

This study investigates precipitation over the Maritime Continent, comparing the precipitation simulated by a 20 km-grid Meteorological Research Institute General Circulation Model (MRI-GCM) and the nearsurface rain data of TRMM 2A25. The focus is particularly the diurnal cycle and its phase distribution of precipitation. The features of the simulated precipitation mostly agree well with observations made over islands and straits having horizontal scales smaller than 200 km. However, these are quite different around larger islands, such as Sumatra and Borneo, particularly in the phase of the diurnal cycle. The MRI-GCM indicates maximum pre cipitation in the early afternoon on these islands, while the observed precipitation has its maximum at night. In particular, over the inland areas of the larger islands, the simulated diurnal cycle has almost a reversed phase. The simulated precipitation is remarkably weaker than the observation around the western coast of Sumatra Island, where a large discrepancy is also found in the phase distribution along a line perpendicular to the coast. A higher-resolution simulation using a nonhydrostatic model without convective parameterizations substantially improves the phase distribution over Borneo Island. The non-hydrostatic model simulates well the migration of the precipitation zone and the daily maximum at night in the inland areas. In contrast, the GCM fails to simulate the diurnal cycle over islands whose horizontal scale is larger than 200 km, although the 20 km grid spacing is small enough to reproduce the major aspects of the local circulations. The cause for this seems to be the cumulus convective parameterization, which may not adequately represent the coupling of convection and local circulations.

“…Therefore, the projection of climate changes in such Baiu frontal precipitation with 5km-NHM is an important challenge. Several results of this experiment have already been published Hashimoto et al 2005;Kanada et al 2005;Wakazuki et al 2005;Yasunaga et al 2005;Yasunaga et al 2006;Nakamura et al 2008).…”

Section: Introductionmentioning

confidence: 87%

“…Yasunaga et al (2006) investigated climatological changes in precipitation systems in the Baiu frontal zone defined as clusters of precipitation grids with 5km-NHM. They pointed out that the increase in the number of largerscale systems with the area larger than 90,000 km 2 , which corresponds to a meso-α-scale, was significant around Kyushu, while increases in the number of larger systems in other regions and that of the smaller systems were not.…”

Section: Projection Of Extreme Precipitation In the Future And Discusmentioning

confidence: 99%

Climatological Reproducibility Evaluation and Future Climate Projection of Extreme Precipitation Events in the Baiu Season Using a High-Resolution Non-Hydrostatic RCM in Comparison with an AGCM

Wakazuki

Nakamura²,

Kanada³

et al. 2008

Self Cite

This paper studies an evaluation of climatological reproducibility and one of future climate projections of extreme precipitation in the Baiu season (from mid-May to July) around Japan using data of numerical experiments. The models are a non-hydrostatic cloud-system-resolving atmospheric model with a horizontal grid size of 5 km (5km-NHM) utilized as a regional climate model (RCM), and an atmospheric general circulation model (AGCM) with a horizontal resolution of about 20 km (20km-AGCM) which provided the boundary condition of 5km-NHM. Ten-year runs were performed by the time-slice method. The mean precipitation amount of the three heaviest precipitation events that ranked in order of precipitation amount in every year (P Top3 ) at each grid point was used as an index to examine quantitatively extreme precipitation within a specific term with various precipitation accumulation periods (APs).The 5km-NHM experiment reproduced P Top3 much better than that of 20km-AGCM, especially for shorter APs. In the projection of P Top3 in the future climate with 5km-NHM, ratio in two climate states of P Top3 for longer APs and that of precipitation amount show the roughly same pattern. The increase areas of those were localized around Kyushu, Japan. In particular, the P Top3 for longer APs was projected to increase 30−70% in the mountainous areas along the Pacific coast of western Japan. This increase was due to a cyclonic circulation of an incremental low-pressure generated on the western side of Kyushu. On the other hand, large increases of P Top3 for shorter APs spread widely with a scattered pattern to the area where precipitation decreases. This characteristic was associated with the intensification of precipitation due to global warming.