Acta Geographica Sinica ›› 2009, Vol. 64 ›› Issue (1): 117-127.doi: 10.11821/xb200901012

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Multitime Scale Correlations Between Runoff and Regional Climate Variations in the Source Region of the Yellow River

SUN Weiguo1, CHENG Bingyan2, LI Rong3   

  1. 1. College of Applied Meteorology,Nanjing University of Information Science and Technology,Nanjing 210044,China;
    2. Climate Center of Chongqing City,Chongqing 401147,China;
    3. Zhengzhou Meteorological Bureau,Zhengzhou 450005,China
  • Received:2008-09-09 Revised:2008-11-10 Online:2009-01-25 Published:2009-01-25
  • Supported by:

    National Natural Science Foundation of China, No.40675067;Scientific Research Fund from Nanjing University of Information Science and Technology, No.9922

Abstract:

The cross wavelet transform method is adopted to study the time-frequency characteristics and multitime scale correlations between the runoff and precipitation, evaporation, maximum and minimum temperature in the source region of the Yellow River. The results show that the variations of runoff and regional climate in the source region of the Yellow River present periodic oscillations of different significance in frequency space and the localization characteristics in time space. There are significant periods at scales of quasi-biannual, 4a, 6-8a, 12-14a and above 20a in both of the runoff and regional climate variations. The power of periodic oscillation at different frequency scales and phase differences in time space are important causes for the unstableness and the lag correlations. The coherence of positive correlation between runoff and regional precipitation is the highest in the climatic factors, indicating that the variations of regional precipitation have a predominant effect on the runoff variations. The unconventionality of regional precipitation at pre-period has durative influence on the runoff. Negative correlation between runoff and regional evaporation is significant, but unstable with lag correlations on the interannual timescale. The coherence of negative correlation between runoff and maximum temperature is higher than the positive correlation between runoff and minimum temperature on interdecadal timescale, that is to say, the effect of decreasing the runoff supply due to maximum temperature rise induced the regional evaporation increase is greater than the effect of increasing the runoff supply due to minimum temperature rise caused ice thawing and snowmelt in the long term change. The unstableness of the interannual timescale correlations between runoff and maximum and minimum temperature is distributed in some of the time space. And the phase differences of them indicate that responding time of runoff to temperature variations is different. Analysis makes it known that the primary factor is the regional precipitation on the runoff variations, maximum temperature is important factor, and the regional evaporation and minimum temperature also have different influences on the runoff variations. Synthetic effect of regional climatic elements is the prime cause for runoff variations in the source region of the Yellow River.

Key words: source region of the Yellow River, runoff, climate change, cross wavelet transform