INDEX OF DIRECTION CHANGE OF ZONALLY AVERAGED WIND AND CHANGE OF SEASON

In this paper, a Wind Direction Change Index （WI）, which can describe four-dimensional spatiotemporal changes of the atmospheric circulation objectively and quantitatively, is defined to study its evolution and seasonal variation. The first four modes can be obtained by EOF expansion of the zonally...

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Published inJournal of Tropical Meteorology Vol. 17; no. 2; pp. 128 - 135
Main Author 朱敏 徐建霞 张铭
Format Journal Article
LanguageEnglish
Published Guangzhou Guangzhou Institute of Tropical & Marine Meteorology 01.06.2011
Meteorological Center of Nanjing Air Force, Nanjing 210018 China%Meteorological Center of Nanjing Air Force, Nanjing 210018 China%Laboratory of Atmospheric Circulation and Short-Range Climate Forecast, Meteorological College, PLA University of Science and Technology, Nanjing 211101 China
Laboratory of Atmospheric Circulation and Short-Range Climate Forecast, Meteorological College, PLA University of Science and Technology, Nanjing 211101 China
Subjects
February stratospheric reverse
Empirical Orthogonal Function (EOF)
Wind Direction Change Index (WI)
four-dimensional space-time changes
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Summary:In this paper, a Wind Direction Change Index （WI）, which can describe four-dimensional spatiotemporal changes of the atmospheric circulation objectively and quantitatively, is defined to study its evolution and seasonal variation. The first four modes can be obtained by EOF expansion of the zonally averaged WI. The first mode reveals the basic spatial distribution of the annually averaged WI. The second mode reflects the quasi-harmonic parts of the WI deviations. Tropical, subtropical and extratropical monsoon areas can be clearly reflected by this mode. The third mode reflects the non-harmonic parts of the WI deviations. It shows the so-called February reverse in stratospheric atmosphere as well as the asymmetric seasonal changes from spring to fall and from fall to spring due to both the land-sea distribution contrast between the Northern and Southern Hemispheres and the nonlinear effect of atmospheric and ocean fluids. The fourth mode reveals the northward advancing of the global reversed wind fields from spring to summer and their southward withdrawal from summer to autumn.
Bibliography:In this paper, a Wind Direction Change Index （WI）, which can describe four-dimensional spatiotemporal changes of the atmospheric circulation objectively and quantitatively, is defined to study its evolution and seasonal variation. The first four modes can be obtained by EOF expansion of the zonally averaged WI. The first mode reveals the basic spatial distribution of the annually averaged WI. The second mode reflects the quasi-harmonic parts of the WI deviations. Tropical, subtropical and extratropical monsoon areas can be clearly reflected by this mode. The third mode reflects the non-harmonic parts of the WI deviations. It shows the so-called February reverse in stratospheric atmosphere as well as the asymmetric seasonal changes from spring to fall and from fall to spring due to both the land-sea distribution contrast between the Northern and Southern Hemispheres and the nonlinear effect of atmospheric and ocean fluids. The fourth mode reveals the northward advancing of the global reversed wind fields from spring to summer and their southward withdrawal from summer to autumn.
Wind Direction Change Index （WI）; Empirical Orthogonal Function （EOF）; four-dimensional space-time changes; February stratospheric reverse
ZHU Min , , XU Jian-xia , ZHANG Ming （1. Laboratory of Atmospheric Circulation and Short-Range Climate Forecast, Meteorological College, PLA University of Science and Technology, Nanjing 211101 China; 2. Meteorological Center of Nanjing Air Force, Nanjing 210018 China）
44-1409/P
SourceType-Scholarly Journals-1
ObjectType-General Information-1
content type line 14
ISSN:1006-8775
DOI:10.3969/j.issn.1006-8775.2011.02.005