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Luni‐solar 18.6‐ and solar cycle 10–11‐year signals in Chinese dryness‐wetness indices
Author(s) -
Currie Robert G.
Publication year - 1995
Publication title -
international journal of climatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.58
H-Index - 166
eISSN - 1097-0088
pISSN - 0899-8418
DOI - 10.1002/joc.3370150503
Subject(s) - dryness , amplitude , phase lag , solar cycle , environmental science , climatology , lag , atmospheric sciences , physics , geology , mathematics , biology , computer network , quantum mechanics , magnetic field , computer science , solar wind , immunology
Power spectrum analysis of 81 long and 202 short Chinese dryness‐wetness indices yields evidence for two peaks with periods near 18.6 and 10.5 years, both of which are statistically significant at confidence levels of 99.9 per cent. They are identified as induced by the 18.6‐year luni‐solar, M n , constituent tide and a 10–11‐year solar cycle, S c , variation in the Sun's luminosity of the order of 0.1 per cent. Amplitude and phase of M n wavetrains are highly non‐stationary with respect to both time and geography; in particular, abrupt 180° phase changes in wave polarity are often observed. Amplitude and phase of S c waves are also highly non‐stationary, with those in northern China out of phase with waves in the south since 1895 (they were in phase from 1815 to 1845). For the 202 short records variance contribution of the two signals to total variance in raw data varied from 6 per cent to 53 per cent, with a mean of 22 per cent, again demonstrating their extreme non‐stationarity. Construction of a dry and very dry drought index (DVDI) shows that since 1470 by far the most prolonged, continuous, and serious drought (due to constructive interference and concomitant high amplitudes of the two waves) occurred from 1633 to 1643; the Ming Dynasty collapsed in 1644 and, in agreement with Hameed and Gong (1990), it is concluded that this climatic disaster was a causal factor in the fall of the Ming Empire.