Journal cover Journal topic
Hydrology and Earth System Sciences An interactive open-access journal of the European Geosciences Union
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
28 Feb 2017
Review status
A revision of this discussion paper was accepted for the journal Hydrology and Earth System Sciences (HESS) and is expected to appear here in due course.
An Investigation into the Relationship between Teleconnections and Taiwan's Streamflow
Chia-Jeng Chen1 and Tsung-Yu Lee2 1National Chung Hsing University, 145 Xingda Road, Taichung, 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 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.

Citation: Chen, C.-J. and Lee, T.-Y.: An Investigation into the Relationship between Teleconnections and Taiwan's Streamflow, Hydrol. Earth Syst. Sci. Discuss.,, in review, 2017.
Chia-Jeng Chen and Tsung-Yu Lee
Chia-Jeng Chen and Tsung-Yu Lee


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Short summary
Seasonal forecasting of regional hydro-climatic variables is not a fantasy as long as such variables are modulated by certain large-scale, reoccurring climate oscillations. In this article, the authors provide both statistical and physical evidence of how Taiwan's summertime streamflow is strongly connected with some climate patterns dominating cyclonic activity in the Northwest Pacific. However, such connection can be strengthened or weakened by climate regime shifts, as a forecasting caveat.
Seasonal forecasting of regional hydro-climatic variables is not a fantasy as long as such...