07 Aug 2023
 | 07 Aug 2023
Status: this preprint is currently under review for the journal CP.

Interdecadal Pacific Oscillation responsible for the linkage of decadal changes in precipitation/moisture in arid central Asia and humid Asian monsoon region during the last millennium

Hongna Xu, Tao Wang, and Huijun Wang

Abstract. Reconstruction and observational studies imply a potential linkage of moisture/precipitation change in arid central Asia and monsoonal East Asia, in which the evolution of moisture/precipitation in central Asia is out-of-phase with that in northern China, but in-phase with that in southern China. In order to ascertain whether there is a robust linkage between the changes in climate in Asian arid regions and monsoon regions and to elucidate the underlying dynamic mechanisms, we analyzed the Last Millennium Reanalysis dataset and output from the Community Earth System Model-Last Millennium Ensemble (CESM-LME). The results indicate a significant decadal linkage between precipitation changes in central Asia’s arid region and the Asian monsoon region during the last millennium, which is primarily driven by the Interdecadal Pacific Oscillation (IPO). In spring, the positive IPO could enhance westerlies over the Mediterranean Sea and to its east, which could transport more water vapor and cause increased precipitation over central Asia. In summer, the positive IPO is accompanied with weakened Asian monsoon and southward Asian subtropical westerly jet, which can lead to increased (decreased) summer precipitation over southern China (over northern China and South Asia). The IPO plays a dominant role in connecting the decadal variations in precipitation between arid central Asia and monsoonal Asia by modulating the precipitation of their respective major rainy seasons. Model results suggest that this decadal linkage stems entirely from the internal variability present in the CESM-LME control and all single-forcing simulations. Changes in external forcing factors do not alter this inherent linkage caused by IPO. Moreover, based on analyses of the aridity index and soil moisture content, this relationship of precipitation variation also causes a similar decadal linkage of moisture changes in central Asia and monsoonal Asia. The differences in the multi-centennial-scale moisture/precipitation variations in the Asian arid region and the monsoon region between the Medieval Climate Anomaly and Little Ice Age are also likely caused by IPO-like sea surface temperature anomalies.

Hongna Xu et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on cp-2023-53', Anonymous Referee #1, 26 Aug 2023
  • CC1: 'Comment on cp-2023-53', Liang Ning, 02 Oct 2023
  • RC2: 'Comment on cp-2023-53', Anonymous Referee #2, 02 Oct 2023

Hongna Xu et al.

Hongna Xu et al.


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Short summary
Both reanalysis data and simulations show, during the last millennium, the evolution of precipitation in central Asia is out-of-phase (in-phase) with that in South Asian monsoon region and most of northern China (southern China) on decadal scale. This linkage of precipitation changes in arid central Asia and humid monsoonal Asia is dominated by the internal variability associated with the Interdecadal Pacific Oscillation and also causes a similar linkage of moisture changes in these two regions.