ISSN 1006-9895

CN 11-1768/O4

Relative Contributions of IPO, AMO and Global Warming to the Land Precipitation in North America

School of Atmospheric Sciences, Nanjing University of Information Science & Technology

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    In this study, we investigate the relative contributions of interdecadal Pacific oscillation (IPO) , Atlantic interdecadal oscillation (AMO) and global warming (GW) to decadal variation of land precipitation in North America from 1934 to 2018. Firstly, through the singular value decomposition (SVD) analysis for North American land precipitation and sea surface temperature (SST) in middle and low latitudes, it is found that IPO (42.33%) and AMO (23.21%) are the main SST modes in winter, and AMO (32.66%) and IPO (21.60%) in summer, to affect the interdecadal variation of the land precipitation. Secondly, the linear regression model is used to analyze the relative contribution of the three signals. The results show that AMO contribute dominantly of North America in summer. IPO plays a role only secondary to IPO, and winter is the opposite. GW also plays an important role. In summer, AMO is the primary contributor to the changes of precipitation in Alaska; In Canada, GW dominates. In USA and Mexico, GW, AMO and IPO are of equal importance; In winter, GW is the primary contributor to the changes of precipitation in Alaska and Canada; IPO dominates in USA and Mexico. In terms of information flow, we have presented the regions of sensitivity to the three modes. We also apply ECHAM 4.6 model to further verify the above results, show that the Indian Ocean is pivotal in having AMO and IPO in effect in causing the precipitation variabilities.

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  • Received:November 12,2020
  • Revised:January 18,2021
  • Adopted:March 29,2021
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