We examined the ocean forcing, associated with the different trends in precipitation between North and South Korea, using GPCC V2018 precipitation and OISST V2 sea surface temperature (SST) for the recent thirty years of 1982-2011. As a result of linear regression, the precipitation trends in the monsoon (June and July) and post-monsoon (August and September) seasons were different between North and South Korea, respectively, with increased and decreased trends, during the both monsoon seasons. During the monsoon season, the results of detrended correlation and composite analysis showed the opposite relationships of precipitation with SSTs in the equatorial Pacific and Arctic Oceans between North and South Korea. It was identified that large-scale atmospheric circulation linked to ENSO can differently affect the Korean Peninsula. On the other hand, during the post-monsoon season, the correlation and composite patterns across the oceans in the Northern Hemisphere were generally similar for the two Koreas. It was suggested that near the ocean of the Korean Peninsula and the land surface forcings might affect the precipitation variability during the post-monsoon season, especially in North Korea.

We explored the transporting processes for the Asian dust observed over South Korea. The frequency of Asian dust days (ADDs) were used to analyze the associations of the ADDs with land surface conditions over the four source regions, including inner-Mongolia, the Gobi Desert, Manchuria, and Loess Plateau, and atmospheric synoptic variables over central and eastern Asia. Precipitation and Palmer Drought Severity Index (PDSI) in the source regions during the previous summer were negatively correlated with the ADDs in South Korea. Statistically and physically more significant processes were found in the associations of atmospheric synoptic conditions with the ADDs. The intensified winds of northwesterly-northerlynorthwesterly over a pathway of the Asian dust from the source regions to South Korea were identified during high ADDs years in South Korea. A dipole pattern of anti-cyclonic and cyclonic anomalies over central and eastern Asia, respectively, supported the Asian dust pathway.

We examined if the enhanced forests could modify thermal climatic conditions in the southwestern China and its surrounding regions. We used the continuous time-series of annual forests fraction obtained from He et al. (2017) and sensible heat flux and temperatures from the European Center for Medium- Range Weather Forecasts reanalysis (ERA-Interim) for 1982-2011. In the linear regression trend analysis, the forests fraction, area-averaged over the southwestern China, significantly increased by 15.46% over the three decades. Significantly negative correlations of surface sensible heat flux during the summer growing season (June through August, JJA) with the area-averaged time-series of annual forests fraction were shown in the southwestern China. Correspondingly, the significantly negative correlations of JJA temperature at 925hPa with the annual forests fraction were observed in the southwestern China as well as the surrounding regions propagated to the east. The spatial patterns of negative correlations between the thermal climatic variables and forests fraction were consistent with the difference patterns of sensible heat flux and temperatures between high-fraction and low-fraction years of forests in the southwestern China. The results indicated that the enhanced forests in the southwestern China could reduce thermal energy transfer from land to atmosphere during JJA and, consequently, lower atmospheric temperatures. Based on the temperature trend analysis using the Chinese weather station data, we inferred that the forest-induced cooling effect might be one of the factors of relatively less summer warming, even cooling, trends in the southern China.

이 연구는 남부 아시아 지역에서의 식생활동과 엘니뇨-남방진동(ENSO)현상과 관련된 적도 기후 간의 관련성을 상관 및 회귀 분석을 통하여 규명하였다. 남부 아시아의 표준화된 식생 지수(NDVI)는 적도 동태평양 NINO 3.4 지역의 상층대기 장파복사플럭스 그리고 해수면 기압과 유의한 양의 상관성을 보였고, 해수면 온도 그리고 850hPa 동서 바람장과는 유의한 음의 상관성을 나타냈다. 이러한 ENSO 기후와 남부 아시아 지역의 식생활동 간의 부적인 관련성은 El Niño해에 보여지는 남부 아시아 지역에서의 건조 기후와 관련이 있다. 남부아시아 계절별 NDVI의 총 변동성의 58%가 회귀모델에서 선택된 2개의 변수들에 의해 설명 되었다.회귀모델 결과들은 모델 잔차들의 정규성 및 독립성을 보여 주었고, 또한 관측 NDVI와 모델에 의한 예측NDVI 간의 일치성이 통계적으로 검증 되었다.

The observed relationships between the Asian summer monsoon and the sea surface temperature (SST) anomalies in the northwestern Pacific (NW Pacific) are verified using the intermediate complexity global climate model (GCM) (Planet Simulator: PLASIM). The climate responses over Asia for the monsoon season to forcing from NW Pacific SST anomalies are simulated in the GCM with the enhanced SST anomalies in the NW Pacific for the pre-monsoon season compared to climatological SST. During the pre-monsoon season, the enhanced SST anomalies result in an increase in lower-level convection and precipitation in the NW Pacific. A significantly weakened Indian summer monsoon is simulated for the enhanced SST experiment in the NW Pacific for the pre-monsoon season (p-value＜0.05). PLASIM dose a good job at representing the observed patterns of zonally averaged surface temperature, precipitation, and 850 hPa u-wind, although with some regional differences from observations (p-values of zonal correlation coefficients＜0.01).