scholarly journals Hydrological alteration of the upper Yangtze River and its possible links with large-scale climate indices

2019 ◽  
Vol 50 (4) ◽  
pp. 1120-1137
Author(s):  
Qianjin Dong ◽  
Debin Fang ◽  
Jian Zuo ◽  
Yongqiang Wang
Keyword(s):  
Yangtze River ◽  
Water Resource Management ◽  
Large Scale ◽  
Phase Relationship ◽  
Wavelet Coherence ◽  
Climate Indices ◽  
Hydrological Alteration ◽  
Upper Yangtze River ◽  
The Relationship ◽  
The Upper Yangtze River

Abstract The relationship between hydrological alteration and climate variability in the upper Yangtze River is not fully understood. In this paper, the periodicity features and the intercorrelation of annual and seasonal eco-flow metrics at the Yichang gauge station are analyzed for the period 1882 to 2013. Analysis is carried out to explore the formation of the eco-flow metrics and the possible linkages between eco-flow metrics and selected climate indices, using the cross-wavelet and wavelet coherence methods on data from 1948 to 2013. The results show that the variation of eco-flow metrics correlates well with some selected climate indices, but changes in different eco-flow metrics are complex. Most annual and seasonal eco-flow metrics correlate well with the Northern Hemisphere (N.H) and Indian Ocean Dipole (IOD) and have a significant common power in the two to four years band. In addition, most annual eco-flow metrics have an obvious phase relationship with the selected climate indices. However, the seasonal eco-flow metrics have no significant phase relationship with the selected climate indices. These findings provide a better understanding of how hydrological alterations of the streamflow and better water resource management can ensure ecosystem sustainability for the Yangtze River.

scholarly journals An Investigation into the Relationship between Teleconnections and Taiwan's Streamflow

2017 ◽  
Author(s):  
Chia-Jeng Chen ◽  
Tsung-Yu Lee
Keyword(s):  
Large Scale ◽  
Critical Role ◽  
Phase Relationship ◽  
Temporal Variations ◽  
Prediction Skill ◽  
Climate Indices ◽  
Pacific Basin ◽  
Linear Regression Models ◽  
Quasi Biennial Oscillation ◽  
The Relationship

Abstract. Interannual variations in catchment streamflow represent an integrated response to anomalies in regional moisture transport and atmospheric circulations and are ultimately linked to large-scale climate oscillations. This study investigates the relationship between Taiwan’s long-term summertime (July to September, JAS) streamflow and manifold teleconnection patterns. Lagged correlation analysis is conducted to calculate how JAS streamflow data derived at 28 upstream and 13 downstream gauges in Taiwan correlate with 14 teleconnection indices in the current or preceding seasons. Of the many indices, the West-Pacific and Pacific-Japan (PJ) patterns, both of which play a critical role in determining cyclonic activity in the western North Pacific basin, exhibit the highest concurrent correlations (most significant r = 0.50) with the JAS flows in Taiwan. Alternately, the Quasi-Biennial Oscillation averaged over the period from the previous October to June of the current year is significantly correlated with the JAS flows (most significant r = −0.66), indicating some forecasting utility. By further examining the correlation results using a 20-year moving window, peculiar temporal variations and possible climate regime shifts (CRSs) can be revealed. To identify suspicious, abrupt changes in the correlation, a CRS test is employed. The late 1970s and 1990s are identified as two significant change points, and during the intermediate period, a marked in-phase relationship (r > 0.8) between Taiwan's streamflow and the PJ index is observed. Linear regression models that incorporate the climate indices into streamflow prediction are found to provide reasonable prediction skill in general, and the models are then used to illustrate the dramatic variations in prediction skill from the pre- to post-regime shift epoch. It is verified that the two shifts are in concordance with the alteration of large-scale circulations in the Pacific basin. The changes in pattern correlation and composite maps before and after the change point are discussed, and our results suggest that empirical forecasting techniques should take into account the effect of CRSs on predictor screening.

Assessment of soil organic carbon stock in the upper Yangtze River basin

2013 ◽  
Vol 10 (5) ◽  
pp. 866-872 ◽  
Author(s):  
Xiao-guo Wang ◽  
Bo Zhu ◽  
Ke-ke Hua ◽  
Yong Luo ◽  
Jian Zhang ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
River Basin ◽  
Yangtze River ◽  
Carbon Stock ◽  
Yangtze River Basin ◽  
Soil Organic Carbon Stock ◽  
Upper Yangtze River ◽  
Organic Carbon Stock ◽  
The Upper Yangtze River

scholarly journals Evaluation of yield, stability and adaptability of national winter rapeseed regional trials in the upper Yangtze River region in 2017-2018

2020 ◽  
Vol 5 (3) ◽  
pp. 121-128
Author(s):  
Ze’en Yu ◽  
Lixia Luo ◽  
Fang Zhang ◽  
Meiyan Hong ◽  
Xiangxiang Zhang ◽  
...  
Keyword(s):  
Yangtze River ◽  
Yield Stability ◽  
Upper Yangtze River ◽  
River Region ◽  
Winter Rapeseed ◽  
The Upper Yangtze River

scholarly journals Historical drought patterns over Canada and their teleconnections with large-scale climate signals

2018 ◽  
Vol 22 (6) ◽  
pp. 3105-3124 ◽  
Author(s):  
Zilefac Elvis Asong ◽  
Howard Simon Wheater ◽  
Barrie Bonsal ◽  
Saman Razavi ◽  
Sopan Kurkute
Keyword(s):  
Large Scale ◽  
Southern Oscillation ◽  
Low Frequency ◽  
Kendall Test ◽  
Wavelet Coherence ◽  
Climate Indices ◽  
Data Sets ◽  
Canadian Prairies ◽  
Agriculture Industry ◽  
Spatio Temporal

Abstract. Drought is a recurring extreme climate event and among the most costly natural disasters in the world. This is particularly true over Canada, where drought is both a frequent and damaging phenomenon with impacts on regional water resources, agriculture, industry, aquatic ecosystems, and health. However, nationwide drought assessments are currently lacking and impacted by limited ground-based observations. This study provides a comprehensive analysis of historical droughts over the whole of Canada, including the role of large-scale teleconnections. Drought events are characterized by the Standardized Precipitation Evapotranspiration Index (SPEI) over various temporal scales (1, 3, 6, and 12 consecutive months, 6 months from April to September, and 12 months from October to September) applied to different gridded monthly data sets for the period 1950–2013. The Mann–Kendall test, rotated empirical orthogonal function, continuous wavelet transform, and wavelet coherence analyses are used, respectively, to investigate the trend, spatio-temporal patterns, periodicity, and teleconnectivity of drought events. Results indicate that southern (northern) parts of the country experienced significant trends towards drier (wetter) conditions although substantial variability exists. Two spatially well-defined regions with different temporal evolution of droughts were identified – the Canadian Prairies and northern central Canada. The analyses also revealed the presence of a dominant periodicity of between 8 and 32 months in the Prairie region and between 8 and 40 months in the northern central region. These cycles of low-frequency variability are found to be associated principally with the Pacific–North American (PNA) and Multivariate El Niño/Southern Oscillation Index (MEI) relative to other considered large-scale climate indices. This study is the first of its kind to identify dominant periodicities in drought variability over the whole of Canada in terms of when the drought events occur, their duration, and how often they occur.

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