Igneous rocks in the South China Sea have broad prospects for oil and gas exploration.Integrated geophysical methods are important approaches to study the distribution of igneous rocks and to determine and identify ig...Igneous rocks in the South China Sea have broad prospects for oil and gas exploration.Integrated geophysical methods are important approaches to study the distribution of igneous rocks and to determine and identify igneous rock bodies.Aimed at the characteristics of gravity and magnetic fields in the South China Sea,several potential field processing methods are preferentially selected.Reduction to the pole by variable inclinations in the area of low magnetic latitudes is used to perform reduction processing on magnetic anomalies.The preferential continuation method is used to separate gravity and magnetic anomalies and extract the gravity and magnetic anomaly information of igneous rocks in the shallow part of the South China Sea.The 3D spatial equivalent distribution of igneous rocks in South China Sea is illustrated by the 3 D correlation imaging of magnetic anomalies.Since the local anomaly boundaries are highlighted gravity and magnetic gradients,the distribution characters of different igneous rocks are roughly outlined by gravity and magnetic correlation analysis weighted by gradient.The results show the distribution of igneous rocks is controlled and influenced by deep crustal structure and faulting.展开更多
The characteristics of quasi-biweekly oscillation（QBWO） over the South China Sea during early summer are investigated.Composite results demonstrate that QBWO convection and the meridional wind anomaly exhibit local ...The characteristics of quasi-biweekly oscillation（QBWO） over the South China Sea during early summer are investigated.Composite results demonstrate that QBWO convection and the meridional wind anomaly exhibit local variation,while the zonal wind anomaly displays zonal propagation.Besides,emergence of the zonal wind anomaly precedes the enhancement of QBWO convection,suggesting the zonally propagating zonal wind anomaly may play a key role in initiating the development of QBWO convection.Diagnostics of the convergence of moisture flux and divergence tendency indicate that QBWO convection is primarily modulated by eddy divergence.Among the contributing factors in the divergence tendency,the β effect associated with the zonally-propagating zonal wind anomaly makes an appropriate phase difference with the eddy divergence,which can contribute to the convergence tendency in the initial stage of QBWO.As a result,QBWO convection and the meridional wind anomaly are enhanced,thus facilitating the initial development of QBWO convection over the SCS during early summer.展开更多
North-south displacements and meridional vacillations of the eddy-driven jet are widely accepted as the dominant cause of variability of the observational zonal-mean zonal wind anomalies(denoted [u]').In this stud...North-south displacements and meridional vacillations of the eddy-driven jet are widely accepted as the dominant cause of variability of the observational zonal-mean zonal wind anomalies(denoted [u]').In this study,a new idea regarding the primary variability of the observational [u]' in the middle latitude troposphere is presented.It is hypothesized that there are two different classes of primary variability of the observational [u]':the poleward propagation of the [u]'(abbreviated as PP) and meridional vacillations.To validate this hypothesis,one-point correlation maps of [u]' at 200-hPa during the boreal cold season(November-April) of every year from 1957-2002 are used as a criterion.Twelve PP years,in which the PP events are dominant in the variability of [u]',and 15 no_PP years,in which the PP events are recessive and the meridional vacillations are dominant in the variability of [u]',are examined.The results show that the variabilities of [u]' are different in the chosen PP and no_PP years.In the PP years,the PP events dominate the variability of [u]';however,the meridional vacillations are prevalent in the no_PP years.展开更多
A juvenile specimen of the black turtle, Chelonia mydas agassizii, was located in the shores of Cabo Tamar Island in the western entrance of the Strait of Magellan, Chile. A king crab angler found the specimen, and do...A juvenile specimen of the black turtle, Chelonia mydas agassizii, was located in the shores of Cabo Tamar Island in the western entrance of the Strait of Magellan, Chile. A king crab angler found the specimen, and donated it to the Río Seco Natural History Museum’s vertebrate collection for further studies and exhibition. Morphological measurements and a genetic analysis derived from an mtDNA fragment amplified and sequenced, suggest that this specimen corresponds to the species Chelonia mydas agassiizii and that it is closely related to the Galapagos Islands black turtle population. Possible influences of the El Ni？o Southern Oscillation phenomenon on this tropical species in the Eastern South Pacific Ocean are briefly discussed.展开更多
By using the observational O3 data of Kunming and Hong Kong during the period of 1997 – 2001, the paper studies the distribution and variation of total ozone in low latitude region of China. The study shows that the ...By using the observational O3 data of Kunming and Hong Kong during the period of 1997 – 2001, the paper studies the distribution and variation of total ozone in low latitude region of China. The study shows that the characteristics of variation in Kunming and Hong Kong are very similar, and the total ozone in the western areas is larger than in the eastern ones. It is maximum in summer and minimum in winter.展开更多
The Southern Annular Mode(SAM)is the leading mode of atmospheric variability in the mid–high latitudes of the Southern Hemisphere,representing large-scale variations in pressure and the polar front jet(PFJ).In SAM ev...The Southern Annular Mode(SAM)is the leading mode of atmospheric variability in the mid–high latitudes of the Southern Hemisphere,representing large-scale variations in pressure and the polar front jet(PFJ).In SAM events,the combination of the SAM and other modes may result in different atmospheric patterns.In this study,a neural-network-based cluster technique,the self-organizing map,was applied to extract the distinct patterns of SAM events on the monthly time scale based on geopotential height anomalies at 500 hPa.Four pairs of distinguishable patterns of positive and negative SAM events were identified,representing the diversity in spatial distribution,especially the zonal symmetry of the center of action at high latitudes—that is,symmetric patterns,split-center patterns,West Antarctica patterns,and a tripole pattern.Although the SAM is well known to be beltshaped,within the selected SAM events,the occurrence frequency of symmetric patterns is only 23.8%—less than that of West Antarctica patterns.Diverse PFJ variations were found in the symmetric and asymmetric patterns of SAM events.The more asymmetric the spatial distribution of the pressure anomaly,the more localized the adjusted zonal wind anomaly.The adjusted PFJ varied in meridional displacement and strength in different patterns of SAM events.In addition,the entrance and exit of the jet changed in most of the patterns,especially in the asymmetric patterns,which might result in different climate impacts of the SAM.展开更多
Zonal mean annual temperature trends were estimated using four reanalysis and three analysis grid datasets. The trends over land and for the entire globe were estimated from 1958-2001 and 1979-2007, respectively. Esti...Zonal mean annual temperature trends were estimated using four reanalysis and three analysis grid datasets. The trends over land and for the entire globe were estimated from 1958-2001 and 1979-2007, respectively. Estimates of temperature trends over land from Climate Research Unit （CRU） analysis data indicate more intense wanning moving northward, at a rate of about 3.5℃ per century at 65°N, then declining further to the north. CRU estimates indicated dramatic warming over the latitudes of the Antarctic Peninsula, with a localized cooling trend at 45°S. A global estimate was conducted by comparing estimates of the reanalysis datasets. Temperature distribution trends of the reanalysis data were similar to those generated by land observations but with large bias in the Polar Regions. The bias could be reduced by comparing these estimates with those from the analysis data at high latitudes. Extreme warming trends were esti- mated at rates of 2.9℃-3.5℃ per century in the Arctic and 3.2℃-4.7℃ per century in the Antarctic for 1958-2001. Surface warming was even more intense in the Northern Hemisphere for 1979-2007, with extreme arctic warming rates ranging from 8.5℃-8.9℃ per century, as estimated by the analysis and reanalysis datasets. Trends over Antarctica for this period were contradictory, as Japan Meteorological Agency （JMA） reanalysis （JRA-25） indicated a cooling trend at about -7℃ per century, while other reanalysis datasets showed sharp warming over the continent.展开更多
The authors investigate the characteristics of propagation and the influence on tropical precipitation of 9–29-day intraseasonal variation over midlatitude East Asia during boreal winter, and find that the intraseaso...The authors investigate the characteristics of propagation and the influence on tropical precipitation of 9–29-day intraseasonal variation over midlatitude East Asia during boreal winter, and find that the intraseasonal wind signal can propagate both eastward and southward. In the case of eastward propagation, the intraseasonal wind signal is mainly confined to the midlatitudes, featuring eastward migration of anomalous cyclones and anticyclones. In the case of southward propagation, intraseasonal meridional wind perturbations may extend from the mid to the low latitudes, and even the equatorial region. The accompanying wind convergence/divergence induces anomalous precipitation in the near-equatorial regions, forming a north–south dipole precipitation anomaly pattern between the southern South China Sea and the eastern China– Japan region. An anomalous meridional overturning circulation plays an important role in linking tropical and midlatitude intraseasonal wind and precipitation variations.展开更多
Based on the IDP data from the French DEMETER satellite,global distribution is shown,which corresponds to three precipitation zones:the aural precipitation zone,the mid-high latitude precipitation zone and the South A...Based on the IDP data from the French DEMETER satellite,global distribution is shown,which corresponds to three precipitation zones:the aural precipitation zone,the mid-high latitude precipitation zone and the South Atlantic precipitation zone.Then the Chili earthquake with M8.8 which occurred on February 27,2010 is taken as an example.The IDP fluxes from repeat orbits are compared and the results show that there is a clear enhancement on February 26,2010,just one day ahead of the Chili earthquake.In the south zone with L=2.1～2.7,the flux on February 26 is higher than that on previous days.However in the north zone with L=2.1～2.7,there is no clear change during the day but great enhancement during the night,which is close to the time of the earthquake.At the same time,the flux on February 26 near the equator is far lower than that on previous days.展开更多
Based on four sets of numerical simulations prescribed with atmospheric radiative forcing and sea surface temperature(SST) forcing in the Community Atmospheric Model version 3(CAM3), the interannual and interdecadal v...Based on four sets of numerical simulations prescribed with atmospheric radiative forcing and sea surface temperature(SST) forcing in the Community Atmospheric Model version 3(CAM3), the interannual and interdecadal variabilities of the Antarctic oscillation(AAO) during austral summer were studied. It was found that the interannual variability is mainly driven by SST forcing. On the other hand, atmospheric radiative forcing plays a major role in the interdecadal variability. A cooling trend was found in the high latitudes of the Southern Hemisphere(SH) when atmospheric radiative forcing was specified in the model. This cooling trend tended to enhance the temperature gradient between the mid and high latitudes in the SH, inducing a transition of the AAO from a negative to a positive phase on the interdecadal timescale. The cooling trend was also partly weakened by the SST forcing, leading to a better simulation compared with the purely atmospheric radiative forcing run. Therefore, SST forcing cannot be ignored, although it is not as important as atmospheric radiative forcing.展开更多
基金the National 863 Projects(Nos.2006AA06Z111,2006AA06201-3,and 2006AA09A101-3)National Special Project(No.SinoProbe-01-05)Open Project of the National Key Laboratory for Geological Processes and Mineral Resources(No.GPMR0942).
文摘Igneous rocks in the South China Sea have broad prospects for oil and gas exploration.Integrated geophysical methods are important approaches to study the distribution of igneous rocks and to determine and identify igneous rock bodies.Aimed at the characteristics of gravity and magnetic fields in the South China Sea,several potential field processing methods are preferentially selected.Reduction to the pole by variable inclinations in the area of low magnetic latitudes is used to perform reduction processing on magnetic anomalies.The preferential continuation method is used to separate gravity and magnetic anomalies and extract the gravity and magnetic anomaly information of igneous rocks in the shallow part of the South China Sea.The 3D spatial equivalent distribution of igneous rocks in South China Sea is illustrated by the 3 D correlation imaging of magnetic anomalies.Since the local anomaly boundaries are highlighted gravity and magnetic gradients,the distribution characters of different igneous rocks are roughly outlined by gravity and magnetic correlation analysis weighted by gradient.The results show the distribution of igneous rocks is controlled and influenced by deep crustal structure and faulting.
基金supported financially by the National Basic Research Program of China[grant number 2014CB953902]the National Natural Science Foundation of China[grant numbers 41275001 and 41475074]
文摘The characteristics of quasi-biweekly oscillation（QBWO） over the South China Sea during early summer are investigated.Composite results demonstrate that QBWO convection and the meridional wind anomaly exhibit local variation,while the zonal wind anomaly displays zonal propagation.Besides,emergence of the zonal wind anomaly precedes the enhancement of QBWO convection,suggesting the zonally propagating zonal wind anomaly may play a key role in initiating the development of QBWO convection.Diagnostics of the convergence of moisture flux and divergence tendency indicate that QBWO convection is primarily modulated by eddy divergence.Among the contributing factors in the divergence tendency,the β effect associated with the zonally-propagating zonal wind anomaly makes an appropriate phase difference with the eddy divergence,which can contribute to the convergence tendency in the initial stage of QBWO.As a result,QBWO convection and the meridional wind anomaly are enhanced,thus facilitating the initial development of QBWO convection over the SCS during early summer.
基金sponsored by the National Key Technologies R&D Program of China (Grant No. 2009BAC51B02)the National Basic Research Program of China (973 Program,Grant No. 2010CB950401)+1 种基金the National Nature Science Foundation of China (Grant Nos. U0833602 and 40805023)the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Free Exploration Fund
文摘North-south displacements and meridional vacillations of the eddy-driven jet are widely accepted as the dominant cause of variability of the observational zonal-mean zonal wind anomalies(denoted [u]').In this study,a new idea regarding the primary variability of the observational [u]' in the middle latitude troposphere is presented.It is hypothesized that there are two different classes of primary variability of the observational [u]':the poleward propagation of the [u]'(abbreviated as PP) and meridional vacillations.To validate this hypothesis,one-point correlation maps of [u]' at 200-hPa during the boreal cold season(November-April) of every year from 1957-2002 are used as a criterion.Twelve PP years,in which the PP events are dominant in the variability of [u]',and 15 no_PP years,in which the PP events are recessive and the meridional vacillations are dominant in the variability of [u]',are examined.The results show that the variabilities of [u]' are different in the chosen PP and no_PP years.In the PP years,the PP events dominate the variability of [u]';however,the meridional vacillations are prevalent in the no_PP years.
文摘A juvenile specimen of the black turtle, Chelonia mydas agassizii, was located in the shores of Cabo Tamar Island in the western entrance of the Strait of Magellan, Chile. A king crab angler found the specimen, and donated it to the Río Seco Natural History Museum’s vertebrate collection for further studies and exhibition. Morphological measurements and a genetic analysis derived from an mtDNA fragment amplified and sequenced, suggest that this specimen corresponds to the species Chelonia mydas agassiizii and that it is closely related to the Galapagos Islands black turtle population. Possible influences of the El Ni？o Southern Oscillation phenomenon on this tropical species in the Eastern South Pacific Ocean are briefly discussed.
基金National Natural Science Foundation of China (40265001) Natural Science Foundation ofYunnan Province (2002C0038M)Biography: ZHANG Xiu-nian (1968 –)+2 种基金 male native from Nantong city of Jiangsu Province postgraduate
文摘By using the observational O3 data of Kunming and Hong Kong during the period of 1997 – 2001, the paper studies the distribution and variation of total ozone in low latitude region of China. The study shows that the characteristics of variation in Kunming and Hong Kong are very similar, and the total ozone in the western areas is larger than in the eastern ones. It is maximum in summer and minimum in winter.
基金This work was jointly supported by the National Natural Science Foundation of China[grant numbers 42088101 and 42175019]Guangdong Province Key Laboratory for Climate Change and Natural Disaster Studies[grant number 2020B1212060025].
文摘The Southern Annular Mode(SAM)is the leading mode of atmospheric variability in the mid–high latitudes of the Southern Hemisphere,representing large-scale variations in pressure and the polar front jet(PFJ).In SAM events,the combination of the SAM and other modes may result in different atmospheric patterns.In this study,a neural-network-based cluster technique,the self-organizing map,was applied to extract the distinct patterns of SAM events on the monthly time scale based on geopotential height anomalies at 500 hPa.Four pairs of distinguishable patterns of positive and negative SAM events were identified,representing the diversity in spatial distribution,especially the zonal symmetry of the center of action at high latitudes—that is,symmetric patterns,split-center patterns,West Antarctica patterns,and a tripole pattern.Although the SAM is well known to be beltshaped,within the selected SAM events,the occurrence frequency of symmetric patterns is only 23.8%—less than that of West Antarctica patterns.Diverse PFJ variations were found in the symmetric and asymmetric patterns of SAM events.The more asymmetric the spatial distribution of the pressure anomaly,the more localized the adjusted zonal wind anomaly.The adjusted PFJ varied in meridional displacement and strength in different patterns of SAM events.In addition,the entrance and exit of the jet changed in most of the patterns,especially in the asymmetric patterns,which might result in different climate impacts of the SAM.
基金supported by the National Natural Science Foundation of China (Grant No. 40775048)the National Basic Research Program of China (Grant No. 2006CB400504)Key Projects in the National Science & Technology Pillar Program during the Eleventh Five-Year Plan Period (Grant No. 2007BAC294)
文摘Zonal mean annual temperature trends were estimated using four reanalysis and three analysis grid datasets. The trends over land and for the entire globe were estimated from 1958-2001 and 1979-2007, respectively. Estimates of temperature trends over land from Climate Research Unit （CRU） analysis data indicate more intense wanning moving northward, at a rate of about 3.5℃ per century at 65°N, then declining further to the north. CRU estimates indicated dramatic warming over the latitudes of the Antarctic Peninsula, with a localized cooling trend at 45°S. A global estimate was conducted by comparing estimates of the reanalysis datasets. Temperature distribution trends of the reanalysis data were similar to those generated by land observations but with large bias in the Polar Regions. The bias could be reduced by comparing these estimates with those from the analysis data at high latitudes. Extreme warming trends were esti- mated at rates of 2.9℃-3.5℃ per century in the Arctic and 3.2℃-4.7℃ per century in the Antarctic for 1958-2001. Surface warming was even more intense in the Northern Hemisphere for 1979-2007, with extreme arctic warming rates ranging from 8.5℃-8.9℃ per century, as estimated by the analysis and reanalysis datasets. Trends over Antarctica for this period were contradictory, as Japan Meteorological Agency （JMA） reanalysis （JRA-25） indicated a cooling trend at about -7℃ per century, while other reanalysis datasets showed sharp warming over the continent.
基金supported by the National Natural Science Foundation of China [grant numbers 41530425,41721004,41475081,and 41775080]
文摘The authors investigate the characteristics of propagation and the influence on tropical precipitation of 9–29-day intraseasonal variation over midlatitude East Asia during boreal winter, and find that the intraseasonal wind signal can propagate both eastward and southward. In the case of eastward propagation, the intraseasonal wind signal is mainly confined to the midlatitudes, featuring eastward migration of anomalous cyclones and anticyclones. In the case of southward propagation, intraseasonal meridional wind perturbations may extend from the mid to the low latitudes, and even the equatorial region. The accompanying wind convergence/divergence induces anomalous precipitation in the near-equatorial regions, forming a north–south dipole precipitation anomaly pattern between the southern South China Sea and the eastern China– Japan region. An anomalous meridional overturning circulation plays an important role in linking tropical and midlatitude intraseasonal wind and precipitation variations.
基金sponsored by the Special Scientific Research.Fund of Earthquake Public Welfare Prefession of China(201008007),CEA(02092408)the Sino-Italy Cooperation Project(2009DFA21480)
文摘Based on the IDP data from the French DEMETER satellite,global distribution is shown,which corresponds to three precipitation zones:the aural precipitation zone,the mid-high latitude precipitation zone and the South Atlantic precipitation zone.Then the Chili earthquake with M8.8 which occurred on February 27,2010 is taken as an example.The IDP fluxes from repeat orbits are compared and the results show that there is a clear enhancement on February 26,2010,just one day ahead of the Chili earthquake.In the south zone with L=2.1～2.7,the flux on February 26 is higher than that on previous days.However in the north zone with L=2.1～2.7,there is no clear change during the day but great enhancement during the night,which is close to the time of the earthquake.At the same time,the flux on February 26 near the equator is far lower than that on previous days.
基金supported by the Carbon Budget and Related Issues of the Chinese Academy of Sciences (Grant No. XDA05110201)the National Basic Research Program of China (Grant No. 2010CB951901)
文摘Based on four sets of numerical simulations prescribed with atmospheric radiative forcing and sea surface temperature(SST) forcing in the Community Atmospheric Model version 3(CAM3), the interannual and interdecadal variabilities of the Antarctic oscillation(AAO) during austral summer were studied. It was found that the interannual variability is mainly driven by SST forcing. On the other hand, atmospheric radiative forcing plays a major role in the interdecadal variability. A cooling trend was found in the high latitudes of the Southern Hemisphere(SH) when atmospheric radiative forcing was specified in the model. This cooling trend tended to enhance the temperature gradient between the mid and high latitudes in the SH, inducing a transition of the AAO from a negative to a positive phase on the interdecadal timescale. The cooling trend was also partly weakened by the SST forcing, leading to a better simulation compared with the purely atmospheric radiative forcing run. Therefore, SST forcing cannot be ignored, although it is not as important as atmospheric radiative forcing.
