Nonlinear characteristics of hydroclimate variability in the mid-latitude Asia over the past seven centuries

Abstract

Hydroclimate variations in the mid-latitude Asia have received considerable attention due to its significance for the regional ecosystem and livelihood, while its nonlinear characteristics over the past centuries are not fully understood yet. Hydroclimate patterns for the mid-latitude Asia are classified into eastern and western modes based on a network of the reconstructed Palmer drought severity index (PDSI) of 197 grids spanning since 1300. The hydroclimate variations of western mode are more complex than that of eastern mode based on the Higuchi's fractal dimension (HFD) analysis, which may be related to the complex atmospheric circulation patterns that dominate them. The relationships of the hydroclimate variations between western and eastern modes at different time scales extracted by ensemble empirical mode decomposition method (EEMD) are detected. The anti-phase relationship of the hydroclimatic variations between western and eastern modes at the interdecadal variations occurs during the periods with the enhanced El Nino Southern Oscillation (ENSO) variance. Similarly, the multidecadal hydroclimate variations are anti-phase when the Pacific Decadal Oscillation (PDO) is in its warm phases. The inverse relationship between western and eastern modes is stable for the centennial scale.

Interdecadal moisture patterns and teleconnections in Monsoonal Asia over the past seven centuries

“…Tibetan Plateau), which can modulate the strength of the Asian summer monsoon and the westerlies (Chen et al , , , ; An et al , ; Fang et al , ). Previous studies have stated that the out‐of‐phase interactions are stable on glacial–interglacial, millennial and centennial timescales (Chen et al , , , ; An et al , ; Zhou et al , ). The anti‐phase relationship of hydroclimate changes in the two regions tends to be prominent at the interdecadal timescales when the ENSO variance is enhanced (Zhou et al , ), such as the two periods 1625–1644 and 1975–1999 (Yang et al , ).…”

“…This area is located in the border region of the eastern Asian summer monsoon (EASM). Regional moisture availability is closely linked with a meridional wave train from the Philippine Sea (anti‐cyclone pattern) to South Siberia (anti‐cyclone pattern) with a cyclonic pattern over North China (Qian and Zhou, ; Zhou et al , ), causing enhanced Asia summer monsoon flows into this region. When the monsoon winds are robust and persistent enough to cross the 40°N line, this region would experience a high temperature and rainy season (Jia and Wang, ).…”

“…The ensemble empirical mode decomposition (EEMD) method (Wu and Huang, ), an adaptive and temporally local filter (Qian and Zhou, 2014; Zhou et al , ), is used to extract the interdecadal variations of MADA since 1300. According to the mean periods of the nine timescale components revealed in EEMD, we obtain three major timescale components by summing the first and second components as interannual variability, summing the third, fourth and fifth components as interdecadal variability, taking the sixth, seventh and eighth components as centennial variability (Figure ).…”

“…Numerous approaches have been applied for identifying the homogeneous climatic zones or classifying climate types. The EOF analysis shows high popularity in regionalization of meteorological parameters (Li et al , ; Fang et al , ; Zhou et al , ), in which the covariance of variations can be described using minimal number of extracted principle components that are orthogonal to each other. In addition, clustering analysis is widely used to investigate, interpret and partition given dataset into groups in many climate classification studies (Dikbas et al , ; Sönmez and Kömüşcü, ; Türkeş and Tatli, ; Zhang and Yan, ), which contains hierarchical and nonhierarchical cluster (e.g.…”

A tree-ring δ18O based reconstruction of East Asia summer monsoon over the past two centuries

“…As shown in Fig 7, the reconstructed EASM and the two reconstructed precipitation records exhibit a high degree of coherency at interdecadal scales, with a significant negative correlation (p<0.05) value of -0.56 with the BMJ for 1845-2011, and -0.48 with the AJ for 1870-2013. The correlations are significant (p<0.05) after accounting for the effective degrees of freedom due to the low-pass filtering using the modified Chelton method [49,50,51]. In addition, many anomalous flooding events…”