ChunHo Cho

Regional climate response to land surface changes after harvest in the North China Plain under present and possible future climate conditions

In this study, we investigated the impacts of land use alterations from harvesting practices on the regional surface climate over the North China Plain. The surface climate responses after harvest in June in regions where double-cropping is practiced were evaluated using observations and model simulations with the global climate model HadGEM2-Atmosphere. Responses were modeled under both present and possible future climate conditions. In the model, double-cropping was represented using the monthly varying fraction of vegetation. This contributed to an improvement in the model simulation over East Asia. Modeling results showed that the land surface was warmer and drier after harvest, and these simulation results were consistent with observations. The bare soil surface after harvest in June had biophysical impacts on the surface climate that were mediated by decreasing evapotranspiration and latent heat flux effects, which increased surface air temperatures and decreased surface humidity. An increase in shortwave radiation also contributed to the rise in temperatures. Under two Representative Concentration Pathways (RCP) scenarios for possible future climate conditions, land conversion induced additional warming in addition to greenhouse gases induced global warming. The RCP 8.5 and RCP 2.6 scenarios demonstrated a warming of 1.0°C and 1.4°C due to harvesting practices in June, respectively. The response magnitude was affected by the climate conditions in each RCP. Our results suggest that potential impacts of harvest on the local climate need to be considered in future projections of CO2-induced warming on a regional scale.

Non-stationary Frequency Analysis for Extreme Precipitation based on Representative Concentration Pathways (RCP) Climate Change Scenarios

Due to the Climate Change and Climate Variability in the world, the temperature, precipitation, evaporation etc, hydrologic cycle components are changing rapidly compared with the past. Previous researches have presented many results of extreme hydrological events and frequency increases. In Korea, during latest 10years (1999~2008), the frequency of localized heavy rain above 100 mm in a day occurred totally 385 times, compared 1970~80s when the frequency was 222 times, it increased 1.7 times. For 2011, from early July to mid-August, due to the rainy season and localized heavy precipitation, the accumulated precipitation reached 1285.3 mm. In Seoul and metropolitan areas, the localized heavy precipitation over design precipitation of 100year frequency happened, causing widely flooded area and causing property damage and human casualties in the downtown area. According to the latest extreme flood moved to upper tail of existing probability density function, it is expected that future flood damage frequency and intensity will increase comparing present situation. In this paper, in order to project the future influence of extreme flood of the Korean peninsula, comparing the IPCC 5 Report (AR5), according to the Representative Concentration Pathways (RCP), newly promoted and simulated regional climate model was applied to summary precipitation and considering to the exterior factors, the non-stationary frequency analysis was performed. This result range across the South Korea areas, and the whole increase of extreme precipitation was checked. Especially, following to RCP 4.5 and 8.5 parts, the future 20year frequency average would be reduced to 12.5years, 11.9years separately in the place, so it is expected that the flood safety will be reduced.