The characteristics of circulation corresponding to two kinds of indices of summer monsoon onset over the South China Sea (SCS) have been discussed using the reanalysis data of the National Centers for Environmental P...The characteristics of circulation corresponding to two kinds of indices of summer monsoon onset over the South China Sea (SCS) have been discussed using the reanalysis data of the National Centers for Environmental Prediction-National Center for Atmospheric Research. It is found that there are two patterns of deep convection that occur at different locations and influence the summer monsoon onset over the SCS. One is over the Asia continent and the western Pacific corresponding to the southwesterly of summer monsoon prevailing over the northern and central part of the SCS, while the other is near the Philippines that affects the westerly summer monsoon as prevailing over the central and southern part of the SCS. Since these two kinds of convection affecting the summer monsoon onset do not always occur together, thus the summer monsoon onset time is different when determined by various indices.展开更多
The East Asian monsoon(EAM)exhibits a robust annual cycle with significant interannual variability.Here,the authors find that the EAM annual cycle can be decomposed into the equinoctial and solstitial modes in the com...The East Asian monsoon(EAM)exhibits a robust annual cycle with significant interannual variability.Here,the authors find that the EAM annual cycle can be decomposed into the equinoctial and solstitial modes in the combined sea level pressure,850-hPa low-level wind,and rainfall fields.The solstitial mode shows a zonal pressure contrast between the continental thermal low and the western Pacific subtropical high,reaching its peak in July and dominating the East Asian summer monsoon.The equinoctial mode shows an approximate zonal contrast between the low-level cyclone over the east of the Tibetan Plateau and the western Pacific anticyclone over the east of the Philippines.It prevails during the spring rainy season in South China and reaches its peak in April.The interannual variations of the lead–lag phase of the two modes may result in the negative correlation of rainfall anomalies in North China between spring and fall and in South China between winter and summer,which provides a potential basis for the across-seasonal prediction of rainfall.The warm phase of ENSO in winter could give rise to the reverse interseasonal rainfall anomalies in South China,while the SST anomaly in the Northwest Pacific Ocean may regulate the rainfall anomaly in North China.展开更多
Using merged sea level anomaly and absolute geostrophic velocity products from satellite altimetry and Argos drifter data, we analyzed the reversal process of the South China Sea （SCS） westem boundary current （SCS...Using merged sea level anomaly and absolute geostrophic velocity products from satellite altimetry and Argos drifter data, we analyzed the reversal process of the South China Sea （SCS） westem boundary current （SCSwbc） from a summer to winter pattern in 2011 and important oceanic phenomena during this process. Results show that the outbreak time of the northeast monsoon over the southern SCS lagged that over the northern SCS by about 1 month. During the SCS monsoon reversal period, the SCSwbc reversed rapidly into the winter pattern at the Guangdong continental slope in late September. Subsequently, the southward Vietnam coastal boundary current strengthened. However, the northward Natuna Current maintained a summer state until mid-October. Thus, the balance between the southward and northward currents was lost when they met, their junction moved gradually southward. However, a loop current formed southeast of Vietnam because the main stream of the Vietnam Offshore Current （VOC） remained near its original latitude, Meanwhile, the VOC and associated dipole circulation system strengthened. After mid- October, the northward Natuna Current began to weaken, the loop current finally shed, becoming a cool ring. The VOC and its associated dipole sub-basin circulation system also weakened gradually until it disappeared.展开更多
The characteristics of atmospheric heat source associated with the summer monsoon onset in the South China Sea (SCS) are studied using ECMWF reanalysis data from 1979 to 1993. A criterion of the SCS summer monsoon ons...The characteristics of atmospheric heat source associated with the summer monsoon onset in the South China Sea (SCS) are studied using ECMWF reanalysis data from 1979 to 1993. A criterion of the SCS summer monsoon onset is defined by the atmospheric heat source. Applying this criterion to the 15-year (1979 – 1993) mean field, the onset of the SCS summer monsoon is found to occur in the fourth pentad of May. And this criterion can also give reasonable results for the onset time of the SCS summer monsoon on a year-to-year basis. In addition, pretty high correlation has been found between the onset time of the SCS summer monsoon and the zonal mean vertically integrated heat source <Q1> at 40°S in April. The causes for the late or early onset of the SCS summer monsoon and the close relationship between the onset time and the zonal mean vertically integrated heat source <Q1> at 40 °S in April might be explained by the variations in intensity of the Hadley circulation.展开更多
基金The authors appreciate the support for this work from China Ministry of Education and the Key Laboratory for Tropical Marine Environmental Dynamics(LED)of South China Sea Institute of Oceanology,Chinese Acadermy of Sciences(via KECX2-205).
文摘The characteristics of circulation corresponding to two kinds of indices of summer monsoon onset over the South China Sea (SCS) have been discussed using the reanalysis data of the National Centers for Environmental Prediction-National Center for Atmospheric Research. It is found that there are two patterns of deep convection that occur at different locations and influence the summer monsoon onset over the SCS. One is over the Asia continent and the western Pacific corresponding to the southwesterly of summer monsoon prevailing over the northern and central part of the SCS, while the other is near the Philippines that affects the westerly summer monsoon as prevailing over the central and southern part of the SCS. Since these two kinds of convection affecting the summer monsoon onset do not always occur together, thus the summer monsoon onset time is different when determined by various indices.
基金This work was jointly supported by the National Natural Science Foundation of China[grant numbers 41830969 and 41775052]the National Key R&D Program[grant number 2018YFC1505904]+1 种基金the Basic Scientific Research and Operation Foundation of CAMS[2018Z006 and 2018Y003]It was also supported by the Jiangsu Collaborative Innovation Center for Climate Change.
文摘The East Asian monsoon(EAM)exhibits a robust annual cycle with significant interannual variability.Here,the authors find that the EAM annual cycle can be decomposed into the equinoctial and solstitial modes in the combined sea level pressure,850-hPa low-level wind,and rainfall fields.The solstitial mode shows a zonal pressure contrast between the continental thermal low and the western Pacific subtropical high,reaching its peak in July and dominating the East Asian summer monsoon.The equinoctial mode shows an approximate zonal contrast between the low-level cyclone over the east of the Tibetan Plateau and the western Pacific anticyclone over the east of the Philippines.It prevails during the spring rainy season in South China and reaches its peak in April.The interannual variations of the lead–lag phase of the two modes may result in the negative correlation of rainfall anomalies in North China between spring and fall and in South China between winter and summer,which provides a potential basis for the across-seasonal prediction of rainfall.The warm phase of ENSO in winter could give rise to the reverse interseasonal rainfall anomalies in South China,while the SST anomaly in the Northwest Pacific Ocean may regulate the rainfall anomaly in North China.
基金Supported by the UNESCO-IOC/WESTPAC Project"Response of marine hazards to climate change in the Western Pacific"the Special Fund of Chinese Central Government for Basic Scientific Research Operations in Commonweal Research Institutes(No.GY0212172)+1 种基金the Open Foundation of the Key Laboratory of Data Analysis and ApplicationsState Oceanic Administration(No.LDAA-2012-02)
文摘Using merged sea level anomaly and absolute geostrophic velocity products from satellite altimetry and Argos drifter data, we analyzed the reversal process of the South China Sea （SCS） westem boundary current （SCSwbc） from a summer to winter pattern in 2011 and important oceanic phenomena during this process. Results show that the outbreak time of the northeast monsoon over the southern SCS lagged that over the northern SCS by about 1 month. During the SCS monsoon reversal period, the SCSwbc reversed rapidly into the winter pattern at the Guangdong continental slope in late September. Subsequently, the southward Vietnam coastal boundary current strengthened. However, the northward Natuna Current maintained a summer state until mid-October. Thus, the balance between the southward and northward currents was lost when they met, their junction moved gradually southward. However, a loop current formed southeast of Vietnam because the main stream of the Vietnam Offshore Current （VOC） remained near its original latitude, Meanwhile, the VOC and associated dipole circulation system strengthened. After mid- October, the northward Natuna Current began to weaken, the loop current finally shed, becoming a cool ring. The VOC and its associated dipole sub-basin circulation system also weakened gradually until it disappeared.
基金National Natural Science Foundation of China (40275026) Part One of National KeyFundamental Research and Development Planning Project (G1998040900)
文摘The characteristics of atmospheric heat source associated with the summer monsoon onset in the South China Sea (SCS) are studied using ECMWF reanalysis data from 1979 to 1993. A criterion of the SCS summer monsoon onset is defined by the atmospheric heat source. Applying this criterion to the 15-year (1979 – 1993) mean field, the onset of the SCS summer monsoon is found to occur in the fourth pentad of May. And this criterion can also give reasonable results for the onset time of the SCS summer monsoon on a year-to-year basis. In addition, pretty high correlation has been found between the onset time of the SCS summer monsoon and the zonal mean vertically integrated heat source <Q1> at 40°S in April. The causes for the late or early onset of the SCS summer monsoon and the close relationship between the onset time and the zonal mean vertically integrated heat source <Q1> at 40 °S in April might be explained by the variations in intensity of the Hadley circulation.
