Global response to tropical diabatic heating variability in boreal winter |
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Authors: | Xu Zhang Hai Lin Jing Jiang |
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Institution: | School of Atmospheric Sciences, Nanjing University, Nanjing 210093, Shanghai Typhoon Institute, Chinese Meteorological Administration, Shanghai 200030,Meteorological Research Division, Environmental Canada, Dorval, Quebec, Canada,School of Atmospheric Sciences, Nanjing University, Nanjing 210093 |
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Abstract: | Global teleconnections associated with tropical convective activities were
investigated, based on monthly data of 29 Northern Hemisphere winters:
December, January, February, and March (DJFM). First, EOF analyses were
performed on the outgoing long-wave radiation (OLR) data to characterize the
convective activity variability in the tropical Indian Ocean and the western
Pacific. The first EOF mode of the convective activity was highly correlated
with the ENSO. The second EOF mode had an east--west dipole structure, and
the third EOF mode had three convective activity centers. Two distinct
teleconnection patterns were identified that were associated, respectively,
with the second and third EOF modes. A global primitive equation model was
used to investigate the physical mechanism that causes the global
circulation anomalies. The model responses to anomalous tropical thermal
forcings that mimic the EOF patterns matched the general features of the
observed circulation anomalies well, and they were mainly controlled by
linear processes. The importance of convective activities in the tropical
Indian Ocean and western Pacific to the extended- and long-range forecasting
capability in the extratropics is discussed. |
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Keywords: | diabatic heating teleconnection tropical convective activities |
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