THE MECHANISM OF THICKNESS OF GEOPOTENTIAL HEIGHT DIPOLE AND ITS
RELATION WITH CLIMATE VARIABILITY IN ASIA-AUSTRALIA IN BOREAL WINTER |
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Authors: | BO Yue WANG Cheng-hai and ZHANG Fei-min |
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Institution: | 1. College of Atmospheric Sciences, Lanzhou University, Lanzhou 730000
China; 2. Meteorological Bureau of Yantai Economic and Technological
Development Area, Yantai, Shandong 264006 China |
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Abstract: | With the EOF of reanalysis data being analyzed, a northern-
southern dipole is found in the upper troposphere geopotential height
field of over the Asian-Australian monsoon region in the winter of the
Northern Hemisphere (NH), which is defined as Asian-Australian dipole
(AAD) in this study. Its intensity index is defined as AADI.
Correlation and synthetic analysis illustrate that AADI is closely
related to the weather and climate of Asian-Australian region in boreal
winter. The index can reflect the simultaneous anomalies of temperature
and precipitation on interannual and decadal scales in the boreal
winter of Asian-Australian region. The superposition of the decadal and
interannual signals is significant for the relationship between the
AADI and climate change. The index can be used as an indicator of
intensity of the Asian-Australian monsoon. In the years of strong AADI,
the East Asia major deep trough is stronger, the Subtropical High is
weaker and the Alaska ridge and the westerly jet are stronger than
those in normal years. Enhanced meridional circulation between high and
low latitudes exists in the years of strong AADI. These relationships
reflect the intrinsic link between the anomalies in the upper
troposphere geopotential height and climate in the Asian-Australian
region. |
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Keywords: | Asian-Australian monsoon region Asian-Australian dipole upper troposphere geopotential height anomaly monsoon intensity |
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