a localized heavy rainfall event caused a rapid increase in drainpipe discharge, which killed five people working in a drainpipe near Zoshigaya, Tokyo. This study compared the effects of artificial land cover and anthropogenic heat on this localized heavy rainfall event based on three ensemble experiments using a cloud-resolving model that includes realistic urban features. The first experiment CTRL (control) considered realistic land cover and urban features, including artificial land cover, anthropogenic heat, and urban geometry. In the second experiment NOAH (no anthropogenic heat), anthropogenic heat was ignored. In the third experiment NOLC (no land cover), urban heating from artificial land cover was reduced by keeping the urban geometry but with roofs, walls, and roads of artificial land cover replaced by shallow water. The results indicated that both anthropogenic heat and artificial land cover increased the amount of precipitation and that the effect of artificial land cover was larger than that of anthropogenic heat. However, in the middle stage of the precipitation event, the difference between the two effects became small. Weak surface heating in NOAH and NOLC reduced the near-surface air temperature and weakened the convergence of horizontal wind and updraft over the urban areas, resulting in a reduced rainfall amount compared with that in CTRL.Citation: Souma, K., et al. (2013), A comparison between the effects of artificial land cover and anthropogenic heat on a localized heavy rain event in 2008 in Zoshigaya, Tokyo, Japan,

[1] The effect of Eurasian spring snow amount on East Asian summer monsoon (EASM) rainfall has previously been studied on the basis of both observations and numerical simulations. The results indicate that information on the Eurasian spring snow amount could be important for seasonal prediction of EASM rainfall. Although previous studies identified the effects of snow albedo and melting water of Eurasian snow on global climate, their individual contributions to the prolonged snow effect on early summer regional climate have not been evaluated quantitatively. In this study, the relative importance of the effects of snow albedo and snowmelt water over the Tibetan Plateau on the simulated EASM rainfall is investigated using a regional climate model. Three ensemble simulations were conducted. The first ensemble simulation considers the actual snow cover in the initial condition. The second ensemble simulation ignores the snow effect on the surface albedo in the radiation budget. The third ensemble simulation ignores the infiltration of snowmelt water. A detailed comparison of these simulations indicates that the albedo effect is significant and its effect on rainfall amount over the Yangtze River basin is about three times that of the effect of snowmelt water from May to June. The albedo effect decreased from July to August, while the effect of snowmelt water increased. Eventually, the difference between the two effects became insignificant. Overall, the snow albedo effect over the central and western Tibet appears to dominate the observed relationship between the spring snow anomaly and the EASM rainfall anomaly.Citation: Souma, K., and Y. Wang (2010), A comparison between the effects of snow albedo and infiltration of melting water of Eurasian snow on East Asian summer monsoon rainfall,

The effect of Eurasian spring snow amount on the summer monsoon rainfall over East Asia has been studied both observationally and numerically. The results indicate that the Eurasian spring snow amount could be important for seasonal prediction of East Asian summer monsoon (EASM) rainfall. Therefore, accurately initializing snow could be critical to improving seasonal prediction of EASM rainfall by numerical models. An attempt has been made in this study to initialize snow in a regional climate model using snow water equivalent (SWE) data derived from a microwave imager. Results from an ensemble seasonal prediction experiment for the 2005 EASM show that the satellite-derived SWE data can be effectively used to initialize a dynamical seasonal prediction model, which leads to improved seasonal prediction of EASM rainfall. Possible effects of snow anomalies over the Tibetan Plateau on EASM rainfall were also studied through a comparative ensemble simulation in which snow was initialized by spinning up the same model from the previous winter. It is found that the anomalous snow amount over the Tibetan Plateau could lead to cooling of the surface and lower troposphere not only over the Tibetan Plateau but also in the surrounding areas because of the reduced net surface shortwave radiation associated with the high snow albedo. This would result in positive anomalies in geopotential height and weaken the cyclonic monsoon circulation in the lower troposphere in East Asia, causing a rainfall increase in South China but a reduction in the Yangtze River Valley in early summer (May-June). The difference in rainfall in midsummer (July-August) was not significant when compared with that in early summer. The surface heat budget indicates that the reduced net surface shortwave radiation is largely balanced by the reduced surface sensible heat flux.