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Hydrology and Earth System Sciences An interactive open-access journal of the European Geosciences Union
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Volume 21, issue 7
Hydrol. Earth Syst. Sci., 21, 3463–3481, 2017
https://doi.org/10.5194/hess-21-3463-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Hydrol. Earth Syst. Sci., 21, 3463–3481, 2017
https://doi.org/10.5194/hess-21-3463-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 12 Jul 2017

Research article | 12 Jul 2017

Variations in the correlation between teleconnections and Taiwan's streamflow

Chia-Jeng Chen1 and Tsung-Yu Lee2 Chia-Jeng Chen and Tsung-Yu Lee
  • 1National Chung Hsing University, 145 Xingda Road, South District, Taichung 40227, Taiwan
  • 2National Taiwan Normal University, 162 Heping East Road, Section 1, Taipei 10610, Taiwan

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 conducts correlation analysis to calculate how summertime (July–September, JAS) streamflow data derived at 28 upstream and 13 downstream gauges in Taiwan correlate with 14 teleconnection indices in the current or preceding seasons. We find that the western Pacific (WP) 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. Alternatively, the Quasi-Biennial Oscillation (QBO) 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. A CRS test is employed to identify suspicious and abrupt changes in the correlation. The late 1970s and 1990s are identified as two significant change points. During the intermediate period, Taiwan's streamflow and the PJ index exhibit a marked in-phase relationship (r > 0. 8). It is verified that the two shifts are in concordance with the alteration of large-scale circulations in the Pacific basin by investigating the changes in pattern correlation and composite maps before and after the change point. Our results suggest that empirical forecasting techniques should take into account the effect of CRSs on predictor screening.

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Regional hydro-climatic variables are modulated by large-scale, reoccurring climate oscillations. In this article, the authors provide both statistical and physical evidence of how Taiwan’s summertime streamflow is strongly correlated with specific teleconnection patterns dominating cyclonic activity in the western North Pacific. However, such correlation can be strengthened or weakened by notable climate regime shifts, illustrating the pitfall of empirical seasonal forecasting.
Regional hydro-climatic variables are modulated by large-scale, reoccurring climate...
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