Anomalous Circulation Patterns in Association with Summertime Regional Daily Precipitation Extremes over Northeast China

Abstract

Based on the NCEP/NCAR daily reanalysis product, NOAA monthly sea surface temperature (SST) dataset, and daily precipitation data collected at observational stations provided by Meteorological Information Center of China Meteorological Administration, the present study analyzes characteristic circulation anomalies conducive to regional extreme daily precipitation in the summer over Northeast China. Results indicate that 26 extreme precipitation events occurred during the 36-year period of 1979–2014. The precipitation threshold for the 99th percentile is 22.2 mm/d, and the maximum extreme daily precipitation occurred in Liaoning Province. When extreme precipitation occurs, Northeast China is located to the southeast of an anomalous cyclonic circulation and northwest of an anomalous anticyclonic circulation, where a strong convergence zone is formed in the lower troposphere. The low-level convergence and upper-level divergence as well as the baroclinic circulation structure are favorable for the development of extreme daily precipitation. Meanwhile, there exist two symmetrical meridional circulations to the north and south of Northeast China. The two meridional circulations share the same ascending branch, which is conducive to the occurrence of precipitation. Located in the strong convergence zone to the southeast of the abnormal cyclonic circulation and northwest of the abnormal anticyclonic circulation, huge amounts of water vapor from the Inner Mongolia, Russia, the Japan Sea, and the mid-high latitudes of the Northwest Pacific are transported to Northeast China, providing sufficient water vapor condition for the occurrence of extreme daily precipitation in this region. In addition, daily extreme precipitation in Northeast China is also closely related to the accumulation and convergence of disturbance energy in Northeast China. It may also be related to the abnormal SST distribution that is high in the north and low in the south. Corresponding to extreme daily precipitation, SST anomaly in the Pacific Ocean is roughly characterized by the feature of “positive-north and negative- south” with the equator as the boundary.

The mechanism linking the variability of the Antarctic sea ice extent in the Indian Ocean sector to Indian summer monsoon rainfall

“…These features are associated with an intense anticyclonic wind anomaly over the southwest of the Indian Ocean at about 50° S, implying a more robust divergence anomaly at 250 hPa, leading to more subsidence and more substantial surface convergence. Also, another intense cyclonic wind anomaly can be seen over the polar region at about 70° S and the centre of the Indian Ocean at about 20° S. This cyclonic wind anomaly implies a strong convergence anomaly associated with a strong divergence anomaly at the lower level (Chen et al 2019 ; Zhao et al 2021 ) during the high ice phase years of the PC3 time series of EOF3. It is evident that the high and low ice phase years as inferred from EOF1 and EOF3 influences the middle latitude weather patterns by altering the jet stream characteristics due to increased polar-middle latitude temperature gradient as well as other factors such as the strengthening of the westerly winds.…”

“…The zonal wind anomalies in Fig. 4 a show a positive anomaly over the small parts of the west and east polar regions, a negative anomaly over the high latitudes from about 65° S to 55° S, a positive anomaly from about 45° S to 25° S, and a negative anomaly from about 20° S to 10° S. These features are associated with an intense cyclonic wind anomaly at about 50° S and an intense anticyclonic wind anomaly at about 60° S and 20° S. These cyclonic and anticyclonic wind anomalies imply a strong divergence and convergence anomaly at a lower level (Chen et al 2019 ; Zhao et al 2021 ) during the low ice phase years of the PC1 time series of EOF1. Figure 4 b shows the opposite features of zonal wind anomalies (positive–negative–positive–negative) as well as the wind anomalies.…”

Interannual Variations in Summer Extreme Precipitation Frequency over Northern Asia and Related Atmospheric Circulation Patterns

“…As reviewed in section 1, previous studies have revealed some features of variations in EPE frequency over NEC and the associated mechanisms (e.g., Xu et al 2011;Du et al 2013;Wang et al 2013;Song et al 2015;Wang et al 2017;Yang et al 2017;Cao et al 2018;Han et al 2019;Chen et al 2019). However, limited attention has been given to the interannual variations in EPE frequency over WS and ES.…”

“…Few related studies have examined atmospheric patterns associated with NEC EPE variation. For example, Cao et al (2018) and Chen et al (2019) revealed that NEC EPE variation is related to a dipole circulation pattern over the region. The activity of cutoff lows may contribute to severe summer EPEs over NEC (Zhao and Sun 2007;Hu et al 2010;Cao et al 2018;Tang et al 2021).…”

Large‐scale synoptic atmospheric moisture circulation patterns associated with variability of daily precipitation overEast China

“…To thoroughly investigate the possible relation between the SST variabilities over the North Pacific and India Ocean and precipitation over East China, the SST over the region from 20°E to 65°W and 20°S to 80°N are adopted. Previous studies show these SSTs play a significant impact on the precipitation variabilities over East China (Wang et al ., 2000; Deng et al ., 2014; Wen et al ., 2015; Gao et al ., 2019; Chen et al ., 2019a). All the domains are shown in Figure 1.…”