scholarly journals Interdecadal Change in the Effect of Spring Soil Moisture over the Indo-China Peninsula on the Following Summer Precipitation over the Yangtze River Basin

2020 ◽  
Vol 33 (16) ◽  
pp. 7063-7082
Author(s):  
Chujie Gao ◽  
Gen Li ◽  
Haishan Chen ◽  
Hong Yan
Keyword(s):  
Soil Moisture ◽  
River Basin ◽  
Summer Monsoon ◽  
Land Surface ◽  
Yangtze River ◽  
Yangtze River Basin ◽  
Summer Precipitation ◽  
Interdecadal Change ◽  
The Yangtze River ◽  
The Yangtze River Basin

AbstractThe land surface energy exchange over the Indo-China Peninsula (ICP) is important for regulating regional weather and climate. This work investigates the effect of spring soil moisture (SM) over the ICP on the following summer precipitation over the Yangtze River basin (YRB) during 1961–2010. The results show that the spring SM over the ICP has a significant negative correlation with the following summer YRB precipitation. However, this relationship experiences an obvious interdecadal change with a much stronger correlation in the epoch before the early 1990s (1961–91) than in the later decades (1992–2010). In spring, an abnormally lower SM over the ICP could induce less surface evapotranspiration, increasing local temperature until the summer. Before the 1990s, the resultant anomalous ICP heating raises the local geopotential height, resulting in an excessive westward extension of the western Pacific subtropical high (WPSH). Accordingly, the enhanced southwesterly summer monsoon would transport more moisture to the YRB, intensifying the mei-yu front and local precipitation. In the early 1990s, the East Asian summer monsoon underwent an abrupt change with an interdecadal westward extension of the climatic WPSH. Consequently, the similar abnormal ICP surface heating induced by the anomalous SM would have different influences on the monsoonal circulation, causing a much weaker effect on the YRB precipitation in the recent decades.

Weakening Influence of Spring Soil Moisture over the Indo-China Peninsula on the Following Summer Mei-Yu Front and Precipitation Extremes over the Yangtze River Basin

2020 ◽  
Vol 33 (23) ◽  
pp. 10055-10072
Author(s):  
Chujie Gao ◽  
Gen Li ◽  
Bei Xu
Keyword(s):  
Soil Moisture ◽  
River Basin ◽  
Summer Monsoon ◽  
Yangtze River ◽  
Large Scale ◽  
Asian Summer Monsoon ◽  
Yangtze River Basin ◽  
Precipitation Extremes ◽  
The Yangtze River ◽  
The Yangtze River Basin

AbstractThe seasonal prediction of precipitation extremes over the Yangtze River basin (YRB) has always been a great challenge. This study investigated the effects of spring soil moisture over the Indo-China Peninsula (ICP) on the following summer mei-yu front and YRB precipitation extremes during 1961–2010. The results indicated that the frequency of summer YRB precipitation extremes was closely associated with the mei-yu front intensity, which exhibited a strong negative correlation with the preceding spring ICP soil moisture. However, the lingering climate influence of the ICP soil moisture was unstable, with an obvious weakening since the early 1990s. Due to its strong memory, an abnormally lower spring soil moisture over the ICP would increase local temperature until the summer by inducing less evapotranspiration. Before the early 1990s, the geopotential height elevation associated with the ICP heating affected the western Pacific subtropical high (WPSH), strengthening the southwesterly summer monsoon. Consequently, the mei-yu front was intensified as more warm, wet air was transported to the YRB, and local precipitation extremes also occurred more frequently associated with abnormal ascending motion mainly maintained by the warm temperature advection. In the early 1990s, the Asian summer monsoon underwent an abrupt shift, with the changing climatological states of the large-scale circulations. Therefore, the similar ICP heating induced by the anomalous soil moisture had different effects on the monsoonal circulation, resulting in weakened responses of the mei-yu front and YRB precipitation extremes since the early 1990s.

Biweekly and 21–30-Day Variations of the Subtropical Summer Monsoon Rainfall over the Lower Reach of the Yangtze River Basin

2010 ◽  
Vol 23 (5) ◽  
pp. 1146-1159 ◽  
Author(s):  
Jing Yang ◽  
Bin Wang ◽  
Bin Wang ◽  
Qing Bao
Keyword(s):  
River Basin ◽  
Summer Monsoon ◽  
Yangtze River ◽  
Yangtze River Basin ◽  
Lower Reach ◽  
The Yangtze River ◽  
Intraseasonal Variation ◽  
Low Level ◽  
Anticyclonic Anomaly ◽  
The Yangtze River Basin

Abstract The lower reach of the Yangtze River basin (LYRB) is located at the central region of the mei-yu and baiu front, which represents the subtropical East Asian (EA) summer monsoon. Based on the newly released daily rainfall data, two dominant intraseasonal variation (ISV) modes are identified over the LYRB during boreal summer (May–August), with spectral peaks occurring on day 15 (the biweekly mode) and day 24 (the 21–30-day mode). These two modes have comparable intensities, and together they account for above about 57% of the total intraseasonal variance. Both ISV modes exhibit baroclinic structures over the LYRB at their extreme phases. However, the genesis and evolutions associated with the two modes are different. Considering the genesis of their extreme wet phases over the LYRB, the biweekly mode is initiated by a midlatitude jet stream vorticity anomaly moving southeastward, while the 21–30-day mode is primarily associated with a low-level westward propagation of an anticyclonic anomaly from 145° to 120°E, which reflects the westward extension of the western North Pacific subtropical high (WNPSH). The development of the biweekly mode at LYRB is enhanced by the northwestward movement of a low-level anticyclonic anomaly from the Philippine Sea to the south of Taiwan, which is a result of the enhancement of the WNPSH resulting from its merger with a transient midlatitude high. In contrast, the development of the 21–30-day mode is enhanced by an upper-level trough anomaly moving from Lake Baikal to far east Russia. These two ISV periodicities are also found to be embedded in their corresponding source regions. The new knowledge on the sources and evolutions of the two major LYRB ISV modes provides empirical predictors for the intraseasonal variation in the subtropical EA summer monsoon.

scholarly journals Extratropical Factors Affecting the Variability in Summer Precipitation over the Yangtze River Basin, China

2017 ◽  
Vol 30 (20) ◽  
pp. 8357-8374 ◽  
Author(s):  
Xinyu Li ◽  
Riyu Lu
Keyword(s):  
River Basin ◽  
Yangtze River ◽  
Yangtze River Basin ◽  
Lower Troposphere ◽  
Summer Precipitation ◽  
Physical Factors ◽  
The Yangtze River ◽  
The South ◽  
The North ◽  
The Yangtze River Basin

Abstract The Yangtze River basin (YRB), a typical East Asian monsoon region, experiences a large year-to-year variability in summer precipitation and is subject to both floods and droughts. There is a well-known seesaw relationship in precipitation between the tropical western North Pacific and the YRB, but more than half of the variance in precipitation in the YRB cannot be explained by this seesaw pattern. The authors therefore investigated other physical factors that might affect precipitation in the YRB. The results indicate that the northeasterly anomaly in the lower troposphere to the north of the YRB plays an important role in the variability in precipitation. This northeasterly anomaly is paired with the southwesterly anomaly to the south of the YRB. They both play an important role in water vapor accumulation over the YRB and intensify the meridional gradient of the equivalent potential temperature θe over the YRB by bringing dry and cool air from the north and wet air from the south. This intensified θe gradient favors convective instability and heavier rainfall in the YRB, as previous studies on mei-yu weather have indicated. Furthermore, it is found that the zonally oriented teleconnection along the Asian westerly jet and the meridional displacement of the jet can affect circulation in the lower troposphere and precipitation in the YRB. These results highlight the role of extratropical circulation anomalies and thus contribute to a more comprehensive understanding of the variability of precipitation in the YRB.

scholarly journals Assessment of the reliability of popular satellite products in characterizing the water balance of the Yangtze River Basin, China

2016 ◽  
Vol 47 (S1) ◽  
pp. 8-23 ◽  
Author(s):  
Dan Zhang ◽  
Qi Zhang ◽  
Adrian D. Werner ◽  
Renying Gu
Keyword(s):  
Water Balance ◽  
River Basin ◽  
Land Surface ◽  
Yangtze River ◽  
Yangtze River Basin ◽  
Absolute Error ◽  
The Yangtze River ◽  
Water Balance Components ◽  
The Yangtze River Basin ◽  
Annual Time

This study investigates the water balance of the Yangtze River Basin (YRB) during 2003–2012 using the Tropical Rainfall Measuring Mission precipitation, the Moderate Resolution Imaging Spectroradiometer evapotranspiration and the Gravity Recovery and Climate Experiment total water storage change. The bias, absolute error and correlation coefficient are used to quantify water balance performances at monthly and annual time steps. The results show that the absolute error in the YRB water balance was 18.1 mm/month and 152.5 mm/yr at monthly and annual time steps accounting for 20% and 14% of YRB precipitation, respectively. The three satellite products were combined through a water balance equation to estimate monthly and annual stream flow, which was in error by 19.4 mm/month and 76.7 mm/yr, accounting for 22% and 7% of YRB precipitation, respectively. Trends in YRB water balance components at annual time steps obtained from satellite products were in the range 83–318% of the corresponding trends from alternative datasets (e.g., ground-based measurements, land-surface modelling, etc.), which performed significantly better than monthly time series. The results indicate that the YRB water balance can be evaluated using multiple satellite products to a reasonable accuracy at annual time steps.

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