Biases of North Atlantic Storm Track and Ural Blocking Influencing on East Asian Winter Monsoon Projection

Project: Research

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Researcher(s)

  • Wen ZHOU (Principal Investigator / Project Coordinator)School of Energy and Environment
  • Wen Chen (Co-Investigator)
  • Noel Sebastian KEENLYSIDE (Co-Investigator)
  • Tim WOOLLINGS (Co-Investigator)

Description

Projection of East Asian winter climate under a global warming scenario is verychallenging because unusual and sudden cold weather over Eurasia has become veryfrequent recently, even though people expect warmer winters to accompany globalwarming. The frequent unexpected cold winters of recent decades actually highlightthe need to improve our understanding and prediction abilities.Anomalous East Asian winter monsoons bring extreme winter weather to South China,including Hong Kong. For example, the Hong Kong Observatory recorded 24consecutive cold days from 24 January to 16 February 2008, which was the longestcold spell since 1968. In boreal winter, the eastward extension of the North Atlanticstorm track and the frequency of atmospheric blocking centered over the UralMountains and western Siberia are interrelated. This interrelationship is also closelytied to the occurrence of extreme cold spells in East Asia and the intensity of the EastAsian winter monsoon. However, most general circulation models (GCMs) do notsimulate the spatio-temporal variability of the storm track and blocking very well. It isimportant to understand the biases in the North Atlantic storm track and Ural blockingin order to evaluate the uncertainty in projecting the East Asian winter monsoon.In this study, we propose novel analyses of the relationship between the NorthAtlantic storm track and Ural blocking using reanalysis datasets and the GCMsparticipating in the fifth phase of the Coupled Model Intercomparison Project(CMIP5). First, we will diagnose the relationship between Ural blocking and theNorth Atlantic storm track using observations and CMIP5 GCMs. The majorenergetic and dynamic factors contributing to the biases in this relationship will behighlighted. Second, we will select the GCMs that can best simulate the blocking–storm track relationship, and then project the future changes in RCP4.5 and 8.5 runs.We will explore projection uncertainties in each run. Finally, we will carry outnumerical experiments with different SST conditions over the North Atlantic to verifyour hypothesis.Through this study, we will better understand the inter-model spread of storm trackand Ural blocking simulations and evaluate their impacts on future changes in theEast Asian winter climate. These results should also be important for risk assessmentof extreme winter conditions in Hong Kong under a changing climate.

Detail(s)

Project number9042400
Grant typeGRF
StatusFinished
Effective start/end date1/09/166/08/20

    Research areas

  • Atlantic storm track , Ural blocking , East Asian winter monsoon , Climate change , Climate projection