Future projection of temperature over Korea in global warming using regional climate simulation with the MM5 model

This study investigates future projection of temperature over Korea with MM5 dynamic downscaling simulation for the period of 1971-2100 based on IPCC SRES A1B scenario. The initial and boundary conditions for MM5 is provided from the in the long-term simulation of ECHO-G global coupled model. Regional climate simulation is done with 27 km horizontal resolution. The domain is centered 38oN and 125oE and covers an area of East Asia and the whole Korean Peninsula. To validate the MM5 simulations, CRU data are used during the period of 1971-2000. The simulated temperatures are similar with the observations and reproduce the realistic features to the east of the Korean Peninsula which is characterized by complex mountain regions.

Regional future climate projections for the periods of 2021-2050 and 2071-2100 show temperature increase by 1.3oC and 3.8oC, respectively over Korea. Seasonally, for the period of 2021-2050, temperature rise in summer is 1.5oC and show similar magnitude with that of winter by 1.1oC. For the period of 2071-2100, similar tendency are shown as increases in the summer and winter are 3.8oC and 4.0oC, respectively.

Frequency distributions of daily mean temperature show increase in the mean value without variance change. The mean temperature rising accompanies changes in the events such as frost and ice days, which are based on the fixed threshold. The annual number of the frost days will decrease by 32.6% over the late 21st century with respect to the 1971-2000 period. Moreover, the number of ice days will decrease by 58.9% during the 2071-2100 period. The number of the tropical nights is expected to increase three times larger than that of the 1971-200 period, and the number of the summer days also will increase.

The temperature rising is associated with an increase in the surface specific humidity during the period of 1981-2100, while relative humidity tends to remain approximately constant over the Korean peninsula. It reflects an increase in the moisture holding capacity of the atmosphere in global warming.

Regional climate projection is important since it reflects how many natural systems currently respond to a wide range of climate types, giving insights into their potential to tolerate, and adapt to, projected climate changes. Regional climate projection in his study demonstrated the feasibility of dynamical downscaling techniques for regional climate change evaluation with the MM5 model.