TROPICAL GEOGRAPHY ›› 2018, Vol. 38 ›› Issue (5): 641-650.doi: 10.13284/j.cnki.rddl.003065

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Synthetical Reconstruction of Climate Variation and Characteristics Analysis for the North Tropical of South China during the Period of 11.5-2.5 ka B.P.

WAN Zhiwei,JIA Yulian,JIANG Meixin   

  1. (Key Laboratory of Poyang Lake Wetland and Watershed Research,Ministry of Education,School of Geography and Environment, Jiangxi Normal University,Nanchang 330022,China)
  • Online:2018-09-05 Published:2018-09-05

Abstract:

Based on Composite Plus Scale method, a temperature series with 100-year resolution in South China has been reconditioned by using 5 long term temperature proxy series selected from recent publications. The proxy records include pollens, lake-sediments, sea-sediments and so on. The result suggests that on a millennial scale temperature changes in the region could be divided into three stages. Stage one:11 500-9 500 a B.P. was early Holocene with relatively low temperature. Stage two: 9 500-4 000 a B.P. was mega thermal period during the Holocene. Stage three:4 000-2 500 a B.P. was the beginning of relatively low temperature period. The accumulated anomaly analysis results show that the temperature series could be divided into two cooling stages and one warming stage during the study period. 11 500-9 500 a B.P. and 4 000-2 500 a B.P. belong to the cooling phase; and 9 500-4 000 a B.P. belongs to the warming phase. The results of the MK mutation test show that the UF and UB statistics intersect at 11.3 ka B.P. and 2.7 ka B.P. passed the 95% confidence level to indicate that a mutation had occurred. Power spectrum analysis shows that the climate change has a period of 8.5 ka, 3.9 ka, 1.3-1.4 ka and 0.65 ka. Since the entire study period is 9 ka, the period of 8.5 ka does not make any sense. In addition, since the integrated reconstruction of this study has a resolution of 100 years, the 0.65 ka period may not be reliable. At the same time as the 2.5 ka period does not exceed 95% confidence level, the periods of 3.9 ka and 1.3-1.4 ka should be the main cycle. Wavelet analysis shows that the climate of North tropical of South China had multi-period, multi-scale warming and cooling cycle characteristics. On the millennium scale, 1.3 ka and 3.3-3.9 ka were the main periods of their variation of climate. A series of climatic events can be identified in the sequence, such as 8.2 ka, 7.9 ka, 7.1 ka and 4.1 ka climatic events. The cross wavelet analysis shows that the wavelet coefficients of exceeding 1 were in the period from 2.5 ka B.P. to 7 ka B.P., and the influence of ENSO on the temperature in the North tropical of South China had a significant impact,especially since 7 ka B.P.. The wavelet coherence analysis also shows that the correlation coefficient between the reconstruction sequence of this paper and the ENSO event sequence after 7 ka B.P. is above 0.6 at the scale of 1.6-2.5 ka. Comparisons with temperature sequences reconstructed by different methods in the Northern Hemisphere and other parts of China finds that the temperature changes in the North tropical of South China are in good agreement with those in other places, indicating that environmental changes in this region response to global changes. Nevertheless, there are also some differences, which show that to a certain degree climate change has regional differences in response.

Key words: Holocene, climate change, Composite Plus Scale method, synthetical reconstruction, North tropical of South China