A Comparative Analysis of Primary and Extreme Characteristics of Dry or Wet Status between Asia and North America |
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Authors: | HUA Lijuan MA Zhuguo and ZHONG Linhao |
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Affiliation: | College of Earth Science, Graduate University of Chinese Academy of Sciences, Beijing 100049,Regional Center for Temperate East Asia, Key Laboratory of Regional Climate-EnvironmentResearch for the Temperate East Asia, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029,Laboratory of Cloud-Precipitation Physics and Severe Storms, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029 |
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Abstract: | In this study, the Palmer Drought Severity Index (PDSI) was used to analyze
the average and extreme dry/wet states of Asia and North America from 1953
to 2003. The results indicate that the two continents underwent drying
trends during this period. Compared with North America, Asia showed more
severe drought trends. However, more significant and regular seasonal
variation for drought was found in North America. The driest regions in Asia
were located in the northern region of China, Mongolia, and eastern
mid-Siberian plateau. Most regions in central North America were relatively
wetter than other regions. The northern and southwestern regions of North
America, as well as the Atlantic and Pacific coastal areas, experienced the
most drought during this period. A sharp increase of the drought area and
the number of extreme drought events took place from 1997 to 2003 in both
Asia and North America. Severe drought events were more likely to occur
during the summer on both continents. Asia had the most extreme drought
events during July, but North America reached its highest drought frequency
from June to September. In Asia, a persistent increasing trend of extreme
drought emerged throughout the studied period. However, a more complex
evolution of drought emerged in North America: a decreasing trend appeared
before the mid-1960s and an increasing trend appeared after the late 1970s.
A relatively steady dry/wet status was observed between the mid-1960s and
the late 1970s. The role of exceptional, extreme drought events with respect
to the La Nina event was considered during 1997--2003. |
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Keywords: | mean dry/wet status extreme drought event Asia North America comparative analysis Palmer Drought Severity Index (PDSI) |
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