Seasonal Prediction of Midsummer Extreme Precipitation Days over Northeast China

Abstract

Northeast China (NEC) has sustained economic losses in recent years because of extreme precipitation events. Despite many efforts, it remains very difficult to predict these extreme events. In this study, we documented the characteristics of extreme precipitation days (EPD) over NEC and established a seasonal prediction model using a year-to-year increment (DY) approach. The results show that most of the EPD over NEC occurred during midsummer, along with large values concentrated over the Greater and Lesser Khingan Mountains and Changbai Mountain. Two variables—the preceding early spring soil moisture DY over central Asia and the sea surface temperature DY in the tropical Atlantic Ocean—were used to construct the statistical model to predict the EPD DY over NEC. These two factors influenced the EPD by modulating the moisture transport over NEC. Cross-validation tests for the period from 1962 to 2016 and independent hindcasts for the period from 1997 to 2016 indicated that the two variables gave good predictions of the EPD over NEC. The observed and predicted year-to-year increments in EPD were well correlated, with a correlation coefficient of 0.65 for the period from 1962 to 2016 in the cross-validation test. In addition, the EPD DY covaried coherently with the midsummer precipitation amount DY over NEC, and those two predictors also gave good predictions for the midsummer precipitation amount over NEC. The correlation coefficient is 0.68 between the observed and predicted year-to-year increment in the amount of midsummer precipitation from 1962 to 2016 in a cross-validation test.

Strengthened Relationship between Tropical West Pacific and Midsummer Precipitation over Northeast China after the Mid-1990s

“…Previous studies concerning summer precipitation in NEC have documented the influence of various atmospheric regimes, such as the East Asian monsoon systems (Sun et al 2007(Sun et al , 2017Cao et al 2018), blocking high at high latitudes (Yao and Dong 2000), cold vortex activities in NEC (Shen et al 2011), soil moisture content in northwest Eurasia (Zhu 2011), and the North Atlantic Oscillation (Sun and Wang 2012). For example, the wintertime Northern Hemisphere annual mode and North Pacific Oscillation both affect NEC precipitation during the following summer through modulation of the cold vortex (Liu et al 2002;He et al 2006).…”

“…Z. identified that the late spring precipitation anomaly in the Huang-Huai region is significantly connected with NEC summer precipitation via local soil moisture anomalies. Additionally, Han et al (2015) revealed a significant decrease in NEC precipitation after the late 1990s, and they attributed this decadal shift to the combined effects of the weakened Northeast Asian summer monsoon and changes in the Arctic sea ice area. Wang and He (2015) stated that the Pacific SST anomalies, the Arctic sea ice anomalies, and warming over both the European continent and the Caspian Sea contributed cooperatively to the severe drought in North China and Northeast Asia during summer 2014.…”

“…Additionally, Han et al (2015) revealed a significant decrease in NEC precipitation after the late 1990s, and they attributed this decadal shift to the combined effects of the weakened Northeast Asian summer monsoon and changes in the Arctic sea ice area. Wang and He (2015) stated that the Pacific SST anomalies, the Arctic sea ice anomalies, and warming over both the European continent and the Caspian Sea contributed cooperatively to the severe drought in North China and Northeast Asia during summer 2014. Recently, Han et al (2019b) reported that the preceding soil moisture content in central Asia and the tropical Atlantic SST are efficient indicators of summer precipitation amount and extreme precipitation events in NEC.…”

“…Wang and He (2015) stated that the Pacific SST anomalies, the Arctic sea ice anomalies, and warming over both the European continent and the Caspian Sea contributed cooperatively to the severe drought in North China and Northeast Asia during summer 2014. Recently, Han et al (2019b) reported that the preceding soil moisture content in central Asia and the tropical Atlantic SST are efficient indicators of summer precipitation amount and extreme precipitation events in NEC.…”

“…Feng and Chen (2016) noted that warming SST anomalies in the North Pacific during autumn are followed by strong southeasterly and meridional moisture transport over NEC, leading to regionally intensified snow events. Additionally, Han et al (2018a) determined that winter precipitation at NEC had an intimate association with SST anomalies in the tropical Indian Ocean before the 1990s and with the North Atlantic SST anomalies subsequently.…”