Abstract
Based on observational data and Asian monsoon intensity datasets from China, the relationships between the East Asian winter monsoon index and winter temperature, the East Asian summer monsoon index and Meiyu precipitation over the middle and lower reaches of the Yangtze River, were analyzed. We found that the monsoon signals were reflected in the temperature and Meiyu precipitation variations. Thus, we used the reconstructed Meiyu precipitation and winter temperature series for the past 300 years and detected the summer/winter monsoon intensity signals using multi-taper spectral estimation method and wavelet analysis. The main periodicities of Meiyu precipitation and winter temperature, such as interannual cycle with 2–7-year, interdecadal-centennial cycles with 30–40-year and 50–100-year, were found. The good relationships between the East Asian summer and winter monsoons suggested that they were in phase at 31-year cycle, while out of phase at 100-year cycle, but with 20-year phase difference. In addition, the winter monsoon intensity may be regulated by the North Atlantic Oscillation, the Arctic Oscillation and the Atlantic Multidecadal Oscillation, and the summer monsoon is closely related to the signal intensities of the Pacific Decadal Oscillation.
Highlights
The East Asian monsoon is one of the most important atmospheric circulation systems from middle to high latitudes in the Northern Hemisphere [1]
The studies have been limited by the paucity of historical observational data, as most indices representing East Asian winter monsoon (EAWM) and East Asian summer monsoon (EASM) intensities were established after the 1950s; the indices can only provide data for climate variations at interannual time scales, and most series are too short to examine monsoon intensity changes at interdecadal–centennial time scales
The 2–7-year cycle existed in the EAWM and EASM intensity index series, and some studies have discussed these interannual variations and their relationships with climatic modes including the El Niño Southern Oscillation and the Tropospheric Biennial Oscillation [43,44,45,46]
Summary
The East Asian monsoon is one of the most important atmospheric circulation systems from middle to high latitudes in the Northern Hemisphere [1]. It is possible that the reconstructed Meiyu precipitation and temperature series over the MLRYR contain EASM and EAWM signals.
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