With the development of seismic exploration,passive-source seismic data has attracted increasing attention.Ambient noise passive seismic sources exists widely in nature and industrial production.Passive seismic data i...With the development of seismic exploration,passive-source seismic data has attracted increasing attention.Ambient noise passive seismic sources exists widely in nature and industrial production.Passive seismic data is important in logging while drilling(LWD),large-scale structural exploration,etc.In this paper,we proposed a passive multiple reverse time migration imaging(PMRTMI)method based on wavefield decomposition and normalized imaging conditions method.This method differs from seismic interferometry in that it can use raw passive seismic data directly in RTM imaging without reconstruction of virtual active gather,and we use the wavefield decomposition method to eliminate the low frequency noise in RTM.Further,the energy normalized imaging condition is used in full wavefield decomposition,which can not only enhance the image quality of both edge and deep information but also overcome the wrong energy problem caused by uneven distribution of passive sources;furthermore,this method exhibits high efficiency.Finally,numerical examples with the Marmousi model show the effectiveness of the method.展开更多
In the present study,we analyzed the chemical properties and factors impacting the sea fog water during two sea fog events over the northwestern South China Sea in March 2017,and compared our results with those of oth...In the present study,we analyzed the chemical properties and factors impacting the sea fog water during two sea fog events over the northwestern South China Sea in March 2017,and compared our results with those of other regions.The sea fog water during these two events were highly acidic and their average pH was below 3,which was related to the high initial acidifying potential and large amounts of NOand SOnot involved in the neutralization reaction.The dominant cations in the sea fog water were Naand NH.The primary anions in the sea fog water over the South China Sea were Cland NO,while that over the North Pacific Ocean was mainly SO,and ratios of the three fog water ions near the Donghai Island were similar.Ions in the sea fog water during the two events were mainly derived from marine aerosols,while the difference was that the first low-level sea fog airflow trajectory passed over Hainan Island.Therefore,the proportion of K+in the first sea fog was much higher than that in sea water and the second.Sulfate was the key to fog water nucleation,which made ion concentration in the sea fog water during the second event higher than that during the first.A decrease in average diameter during the first sea fog formation led to an ion concentration increase,while the average diameter of sea fog water during the second event was lower than that during the first,which corresponded with a moderate ion concentration increase.展开更多
基金sponsored by the Natural Science Foundation of China(No.41874139)the Natural Science Foundation of China(No.41674124)Jilin Province Foundation for Excellent Youths(No.20190103139JH)
文摘With the development of seismic exploration,passive-source seismic data has attracted increasing attention.Ambient noise passive seismic sources exists widely in nature and industrial production.Passive seismic data is important in logging while drilling(LWD),large-scale structural exploration,etc.In this paper,we proposed a passive multiple reverse time migration imaging(PMRTMI)method based on wavefield decomposition and normalized imaging conditions method.This method differs from seismic interferometry in that it can use raw passive seismic data directly in RTM imaging without reconstruction of virtual active gather,and we use the wavefield decomposition method to eliminate the low frequency noise in RTM.Further,the energy normalized imaging condition is used in full wavefield decomposition,which can not only enhance the image quality of both edge and deep information but also overcome the wrong energy problem caused by uneven distribution of passive sources;furthermore,this method exhibits high efficiency.Finally,numerical examples with the Marmousi model show the effectiveness of the method.
基金National Key R&D Program of China(2018YFA0605604)Guangxi Key Research and Development Program(AB20159013)+2 种基金Strategic Priority Research Program of Chinese Academy of Sciences(XDA20060503)Key Area R&D Program of Guangdong Province(2020B0101130021)National Natural Science Foundation of China(41675136)。
文摘In the present study,we analyzed the chemical properties and factors impacting the sea fog water during two sea fog events over the northwestern South China Sea in March 2017,and compared our results with those of other regions.The sea fog water during these two events were highly acidic and their average pH was below 3,which was related to the high initial acidifying potential and large amounts of NOand SOnot involved in the neutralization reaction.The dominant cations in the sea fog water were Naand NH.The primary anions in the sea fog water over the South China Sea were Cland NO,while that over the North Pacific Ocean was mainly SO,and ratios of the three fog water ions near the Donghai Island were similar.Ions in the sea fog water during the two events were mainly derived from marine aerosols,while the difference was that the first low-level sea fog airflow trajectory passed over Hainan Island.Therefore,the proportion of K+in the first sea fog was much higher than that in sea water and the second.Sulfate was the key to fog water nucleation,which made ion concentration in the sea fog water during the second event higher than that during the first.A decrease in average diameter during the first sea fog formation led to an ion concentration increase,while the average diameter of sea fog water during the second event was lower than that during the first,which corresponded with a moderate ion concentration increase.
