scholarly journals Seasonal Rainfall Forecasts for the Yangtze River Basin in the Extreme Summer of 2020

Author(s):  
Philip E. Bett ◽  
Gill M. Martin ◽  
Nick Dunstone ◽  
Adam A. Scaife ◽  
Hazel E. Thornton ◽  
...  

AbstractSeasonal forecasts for Yangtze River basin rainfall in June, May–June–July (MJJ), and June–July–August (JJA) 2020 are presented, based on the Met Office GloSea5 system. The three-month forecasts are based on dynamical predictions of an East Asian Summer Monsoon (EASM) index, which is transformed into regional-mean rainfall through linear regression. The June rainfall forecasts for the middle/lower Yangtze River basin are based on linear regression of precipitation. The forecasts verify well in terms of giving strong, consistent predictions of above-average rainfall at lead times of at least three months. However, the Yangtze region was subject to exceptionally heavy rainfall throughout the summer period, leading to observed values that lie outside the 95% prediction intervals of the three-month forecasts. The forecasts presented here are consistent with other studies of the 2020 EASM rainfall, whereby the enhanced mei-yu front in early summer is skillfully forecast, but the impact of midlatitude drivers enhancing the rainfall in later summer is not captured. This case study demonstrates both the utility of probabilistic seasonal forecasts for the Yangtze region and the potential limitations in anticipating complex extreme events driven by a combination of coincident factors.

2018 ◽  
Vol 35 (8) ◽  
pp. 918-926 ◽  
Author(s):  
Philip E. Bett ◽  
Adam A. Scaife ◽  
Chaofan Li ◽  
Chris Hewitt ◽  
Nicola Golding ◽  
...  

2019 ◽  
Vol 34 (3) ◽  
pp. 705-717
Author(s):  
Zhenkuan Su ◽  
Michelle Ho ◽  
Zhenchun Hao ◽  
Upmanu Lall ◽  
Xun Sun ◽  
...  

2012 ◽  
Vol 610-613 ◽  
pp. 1070-1077
Author(s):  
Guang Wen Ma ◽  
Xiang Bao ◽  
Ye Yao Wang

Base on estimate the amount of nitrogen (N) added to the agroecosystem by human activities, and analyze changes in the environment influence of excess N and fertilizer nitrogen use efficiency (FNE) in agricultural fields of the Yangtze River Basin between 1990 and 2000. Excess N is stored in farmland and transferred to water bodies. The excess N stored in farmland was 2.75 Tg N in 1990 and 3.88 Tg N in 2000. The total N transferred to water bodies was 3.45 Tg N in 1990 and 5.07 Tg N in 2000. The FNE decreased by 22.17 % from 1990 to 2000. Changes in the geographic distribution of variational trends of the N budget, N transferred to water bodies, and FNE are more pronounced in the middle and lower reaches of the Yangtze River Basin. We propose effective measures for maximizing the efficiency of N use and reducing the impact of agricultural N on environment in the Yangtze River Basin.


2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
Author(s):  
Ziwei Xiao ◽  
Peng Shi ◽  
Peng Jiang ◽  
Jianwei Hu ◽  
Simin Qu ◽  
...  

A better understanding of the runoff variations contributes to a better utilization of water resources and water conservancy planning. In this paper, we analyzed the runoff changes in the Yangtze River Basin (YRB) including the spatiotemporal characteristics of intra-annual variation, the trend, the mutation point, and the period of annual runoff using various statistical methods. We also investigated how changes in the precipitation and temperature could impact on runoff. We found that the intra-annual runoff shows a decreasing trend from 1954 to 2008 and from upper stream to lower stream. On the annual runoff sequence, the upstream runoff has a high consistency and shows an increasing diversity from upper stream to lower stream. The mutation points of the annual runoff in the YRB are years 1961 and 2004. Annual runoff presents multitime scales for dry and abundance changes. Hurst values show that the runoffs at the main control stations all have Hurst phenomenon (the persistence of annual runoff). The sensitivity analyses of runoff variation to precipitation and temperature were also conducted. Our results show that the response of runoff to precipitation is more sensitive than that to temperature. The response of runoff to temperature is only one-third of the response to precipitation. A decrease in temperature may offset the impact of decreasing rainfall on runoff, while an increase in both rainfall and temperature leads to strongest runoff variations in the YRB.


2020 ◽  
Vol 33 (23) ◽  
pp. 10055-10072
Author(s):  
Chujie Gao ◽  
Gen Li ◽  
Bei Xu

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.


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