In this study, the purpose of the study is to determine the depth of damage caused by early frost damage in concrete slab structures under the conditions of external temperature during winter. In other words, we intend to analyze the depth variation of the early frost damage as the thickness of the concrete slab member changes under the condition of the 3-component binder frequently used in practice. As a result, the thinner the component, the significantly reduced the overall temperature of the concrete. In addition, the thinner the component thickness, the higher the delay in increasing the brightness of the core collected from the concrete member, and the greater the effect on the depth of the early frost damage was on the thinner the component thickness.

Persistent Extreme Temperature Events (PETEs) are defined in two steps; first, to define extreme temperature events, the 80th and 20th percentiles of daily maximum and minimum temperature were chosen. Then individual PETE was defined as an event which lasted three or longer consecutive extreme temperature days. In this study, we examined characteristics and changes of PETEs in Republic of Korea (ROK) using 14 weather stations with a relatively long-term period of data, 1954-2016. In ROK, PETEs lasted four-five days on average and occurred two-three times a year. PETEs lasted longer in summer than in winter and in maximum temperature than in minimum temperature. PETEs which lasted greater than seven days account for a greater proportion in summer than in winter. However, intensities of PETEs were greater in winter because of a larger temperature fluctuation. In both summer and winter, durations and intensities of persistent extreme high temperature events increased while those of persistent extreme low temperature events decreased. Changes of PETEs were closely related with both global warming and diverse large-scale climate variabilities such as AO, NAO and Nino 3.4.

In this paper, for selected station of 8 clusters in East Asia (Park, 2017) more (less) warming periods than the wintertime mean warming of intra-seasonal fluctuation curves were taken and their means were computed. Long term trends and synoptic features of the mean temperature changes were examined. In most clusters, around the third of January there were less warming periods (LWP) than the mean wintertime warming. On the contrary, in February and the first and second of January there were more warming periods (MWP) than the winter mean or LWPs having a warming trend with statistical signicance. Time series of the daily Siberian High indices showed they had been weakening in February and being stagnant around late January. In most stations, the mean temperatures of MWP or LWP had large negative correlation coecients with the Siberian high intensity. is result explains the occurrences of MWPs in most clusters in February and LWPs in late January. In cluster B there were LWPs in early February due to the influence of the Aleutian Low which were strengthening in that periods. Cluster E showed different features without LWPs in late January. The cluster is considered to be affected by its plateau environment of West Yúnnán and the Tibet Plateau which prevent cold air of the lower atmosphere in Northern Asia flowing southward, and by the regional atmospheric circulation of 500hPa surface centered in this region.

In this study, the intra-seasonal fluctuation (ISF) of wintertime temperature change in East Asia was classified by a cluster analysis of complete linkage. A ISF of temperature change was defined as a difference of synthesized harmonics (1 to 36 harmonic) of daily temperature averaged for 30 years (1951~1980, 1981~2010). Eight clusters were gained from the ISF curves of 96 stations in East Asia. Regions of the cluster C, G and A1 seem to be affected by the Siberian High (SH) center, whereas the cluster A1, A2, D, B and F by the SH main pathways. Regions of the cluster E are apart from the SH main pathways and appear to be in the area of influence of other factors. Wintertime temperatures in Northwest China (clusters C, G) and Northeast China (cluster A1) were increased very largely. In most clusters, around late January there were less warming periods than the winter mean of the mean ISF of the clusters, before and after this time there were more warming periods than the winter mean.

The purpose of this study is to characterize long-term (1973~2012) changes in intra-seasonal temperature and extreme low temperature events in winter observed at 61 weather stations in the Republic of Korea and their associations with changes in atmospheric circulation patterns around East Asia. Maps of long-term linear trends clearly show that both temperature means and extreme events in Korea have asymmetrically changed between early winter and late winter. In early winter, changes with statistical significance are less observable, while in late winter reductions in low extreme temperature events as well as increases in temperatures, particularly after mid-1980s, are obviously observed across the study region. Comparisons of tropospheric synoptic climatic fields before and after the mid-1980s demonstrate that in early winter of recent decades, active meridional circulation from the Arctic appeared in western Eurasia and Bering sea, while in late winter, zonal circulation around East Asia associated with positive Arctic Oscillation-like patterns prevailed. These results indicate that asymmetric changes between early and late winter temperatures in Korea are associated with intra-seasonally inconsistent atmospheric circulation patterns around East Asia.

In this study, we analyzed the intraseasonal variability and change of winter temperature over South Korea using long-term observations. The lowest temperature in the wintertime, using daily mean, maximum, and minimum temperature data occurred on January 7th in the period of 2003~2012, while on January 22~25th in the past 30 years(1973~1982, 1983~1992, 1993~2002). Representative seven stations in South Korea also showed consistent result. The strengthening of Siberian High and weakening of Aleutian Low in recent 10 years are found to be closely related with the recent intraseasonal temperature change over South Korea. The baroclinic structure of upper-level low and lower-level high system near Korean peninsula provided good condition for vertical cold-air advection, which resulted in minimum temperature on late January in 1973~1982 and early January in 2003~2012 with strengthened low-level northerly flow.