Loess record of the aerodynamic environment in the east Asia monsoon area since 60,000 years before present
Identifieur interne : 000755 ( Main/Exploration ); précédent : 000754; suivant : 000756Loess record of the aerodynamic environment in the east Asia monsoon area since 60,000 years before present
Auteurs : Xiaoguang Qin [République populaire de Chine] ; Binggui Cai [République populaire de Chine] ; Tungsheng Liu [République populaire de Chine]Source :
- Journal of Geophysical Research: Solid Earth [ 0148-0227 ] ; 2005-01.
Abstract
The multimodal distribution of grains in loess and dust storm deposits has been widely reported in recent years. Our analysis demonstrates that the interaction of wind, atmospheric turbulence, and dust grain gravity along the dust transportation path results in a multimodal grain size distribution for suspended dust. Changes in the median sizes of the coarse and medium modes are related to variation in aerodynamic forcing (lift force related to vertical wind and turbulence) during dust entrainment in the source area and turbulence intensity in the depositional area. On the basis of the numeric characteristics of the three modes of suspended particles, a tentative model has been constructed, which is used to study fluctuations of paleoaerodynamic environments. From a time series of paleoatmospheric environmental changes of the loess plateau for the past 60,000 years, we find that there are three patterns of aerodynamic environments in the dust source area (stronger, strong, weak) and 13 strong turbulence events since 60,000 years B.P. Climatic variability in the dust depositional area is stronger than in the source area. During the last glacial period the aerodynamic environment changed synchronously in the dust source and depositional areas over the entire trend. However, after 8000 years B.P. the aerodynamic force is strong in the dust source area, while the turbulence intensity is weak in the dust depositional area, differing from that of the last glacial period. The strong turbulence periods correspond to the cooling events such as the Heinrich events and the Younger Dryas cold event and may not be related to factors forcing the alternation between glacial and interglacial periods. Since 60,000 years B.P. the three patterns of aerodynamic environments are mainly controlled by the environmental changes in the dust source area and may be related to fluctuations of the winter monsoon. In each pattern, fluctuations of the turbulence intensity in the dust depositional area and the distance from dust source to dust depositional area are the major changes of the environment. The summer monsoon, recorded by magnetic susceptibility, may vary prior to the winter monsoon since 50,000 years B.P. Changes in the intensity of the summer monsoon may force changes in the advance‐retreat cycles of dust source areas in each winter monsoon pattern.
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DOI: 10.1029/2004JB003131
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<record><TEI wicri:istexFullTextTei="biblStruct"><teiHeader><fileDesc><titleStmt><title xml:lang="en">Loess record of the aerodynamic environment in the east Asia monsoon area since 60,000 years before present</title><author><name sortKey="Qin, Xiaoguang" sort="Qin, Xiaoguang" uniqKey="Qin X" first="Xiaoguang" last="Qin">Xiaoguang Qin</name></author><author><name sortKey="Cai, Binggui" sort="Cai, Binggui" uniqKey="Cai B" first="Binggui" last="Cai">Binggui Cai</name></author><author><name sortKey="Liu, Tungsheng" sort="Liu, Tungsheng" uniqKey="Liu T" first="Tungsheng" last="Liu">Tungsheng Liu</name></author></titleStmt><publicationStmt><idno type="wicri:source">ISTEX</idno><idno type="RBID">ISTEX:52BA0F8EA2A1CBBF097FA54AF14FE17CBFC83015</idno><date when="2005" year="2005">2005</date><idno type="doi">10.1029/2004JB003131</idno><idno type="url">https://api.istex.fr/document/52BA0F8EA2A1CBBF097FA54AF14FE17CBFC83015/fulltext/pdf</idno><idno type="wicri:Area/Main/Corpus">000894</idno><idno type="wicri:Area/Main/Curation">000887</idno><idno type="wicri:Area/Main/Exploration">000755</idno><idno type="wicri:explorRef" wicri:stream="Main" wicri:step="Exploration">000755</idno></publicationStmt><sourceDesc><biblStruct><analytic><title level="a" type="main" xml:lang="en">Loess record of the aerodynamic environment in the east Asia monsoon area since 60,000 years before present</title><author><name sortKey="Qin, Xiaoguang" sort="Qin, Xiaoguang" uniqKey="Qin X" first="Xiaoguang" last="Qin">Xiaoguang Qin</name><affiliation wicri:level="3"><country xml:lang="fr">République populaire de Chine</country><wicri:regionArea>Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing</wicri:regionArea><placeName><settlement type="city">Pékin</settlement></placeName></affiliation><affiliation wicri:level="1"><country wicri:rule="url">République populaire de Chine</country></affiliation></author><author><name sortKey="Cai, Binggui" sort="Cai, Binggui" uniqKey="Cai B" first="Binggui" last="Cai">Binggui Cai</name><affiliation wicri:level="3"><country xml:lang="fr">République populaire de Chine</country><wicri:regionArea>Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing</wicri:regionArea><placeName><settlement type="city">Pékin</settlement></placeName></affiliation></author><author><name sortKey="Liu, Tungsheng" sort="Liu, Tungsheng" uniqKey="Liu T" first="Tungsheng" last="Liu">Tungsheng Liu</name><affiliation wicri:level="3"><country xml:lang="fr">République populaire de Chine</country><wicri:regionArea>Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing</wicri:regionArea><placeName><settlement type="city">Pékin</settlement></placeName></affiliation></author></analytic><monogr></monogr><series><title level="j">Journal of Geophysical Research: Solid Earth</title><title level="j" type="abbrev">J. Geophys. Res.</title><idno type="ISSN">0148-0227</idno><idno type="eISSN">2156-2202</idno><imprint><publisher>Blackwell Publishing Ltd</publisher><date type="published" when="2005-01">2005-01</date><biblScope unit="volume">110</biblScope><biblScope unit="issue">B1</biblScope><biblScope unit="page" from="n/a">n/a</biblScope><biblScope unit="page" to="n/a">n/a</biblScope></imprint><idno type="ISSN">0148-0227</idno></series><idno type="istex">52BA0F8EA2A1CBBF097FA54AF14FE17CBFC83015</idno><idno type="DOI">10.1029/2004JB003131</idno><idno type="ArticleID">2004JB003131</idno></biblStruct></sourceDesc><seriesStmt><idno type="ISSN">0148-0227</idno></seriesStmt></fileDesc><profileDesc><textClass></textClass><langUsage><language ident="en">en</language></langUsage></profileDesc></teiHeader><front><div type="abstract">The multimodal distribution of grains in loess and dust storm deposits has been widely reported in recent years. Our analysis demonstrates that the interaction of wind, atmospheric turbulence, and dust grain gravity along the dust transportation path results in a multimodal grain size distribution for suspended dust. Changes in the median sizes of the coarse and medium modes are related to variation in aerodynamic forcing (lift force related to vertical wind and turbulence) during dust entrainment in the source area and turbulence intensity in the depositional area. On the basis of the numeric characteristics of the three modes of suspended particles, a tentative model has been constructed, which is used to study fluctuations of paleoaerodynamic environments. From a time series of paleoatmospheric environmental changes of the loess plateau for the past 60,000 years, we find that there are three patterns of aerodynamic environments in the dust source area (stronger, strong, weak) and 13 strong turbulence events since 60,000 years B.P. Climatic variability in the dust depositional area is stronger than in the source area. During the last glacial period the aerodynamic environment changed synchronously in the dust source and depositional areas over the entire trend. However, after 8000 years B.P. the aerodynamic force is strong in the dust source area, while the turbulence intensity is weak in the dust depositional area, differing from that of the last glacial period. The strong turbulence periods correspond to the cooling events such as the Heinrich events and the Younger Dryas cold event and may not be related to factors forcing the alternation between glacial and interglacial periods. Since 60,000 years B.P. the three patterns of aerodynamic environments are mainly controlled by the environmental changes in the dust source area and may be related to fluctuations of the winter monsoon. In each pattern, fluctuations of the turbulence intensity in the dust depositional area and the distance from dust source to dust depositional area are the major changes of the environment. The summer monsoon, recorded by magnetic susceptibility, may vary prior to the winter monsoon since 50,000 years B.P. Changes in the intensity of the summer monsoon may force changes in the advance‐retreat cycles of dust source areas in each winter monsoon pattern.</div></front></TEI><affiliations><list><country><li>République populaire de Chine</li></country><settlement><li>Pékin</li></settlement></list><tree><country name="République populaire de Chine"><noRegion><name sortKey="Qin, Xiaoguang" sort="Qin, Xiaoguang" uniqKey="Qin X" first="Xiaoguang" last="Qin">Xiaoguang Qin</name></noRegion><name sortKey="Cai, Binggui" sort="Cai, Binggui" uniqKey="Cai B" first="Binggui" last="Cai">Binggui Cai</name><name sortKey="Liu, Tungsheng" sort="Liu, Tungsheng" uniqKey="Liu T" first="Tungsheng" last="Liu">Tungsheng Liu</name><name sortKey="Qin, Xiaoguang" sort="Qin, Xiaoguang" uniqKey="Qin X" first="Xiaoguang" last="Qin">Xiaoguang Qin</name></country></tree></affiliations></record>Pour manipuler ce document sous Unix (Dilib)
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