Organophosphate esters(OPEs)have become one group of chemicals with emerging concern in the marine environment.In this work,we investigated OPEs in the air and seawater of the South China Sea in summer 2019.The concen...Organophosphate esters(OPEs)have become one group of chemicals with emerging concern in the marine environment.In this work,we investigated OPEs in the air and seawater of the South China Sea in summer 2019.The concentrations of∑_(10)OPEs in the atmosphere ranged from 66 to 550 pg/m^(3),with TCIPP,TNBP,TPhP,and TEP predominating in the air.The total dissolved OPE concentrations(∑_(10)OPEs without TEP)measured in high-volume water samples ranged from 300 to 3600 pg/L,with a mean concentration of 1180±910 pg/L.TEP was measured with liquid−liquid extraction(LLE),and it showed the highest concentration(average 2000±1450 pg/L)among the selected OPEs.Total suspended matter associated OPEs accounted for less than 4.7%of the sum of OPE concentrations in seawater.Fugacity fractions and air−sea exchange fluxes showed that TCEP,TCIPP,TIBP,TEHP,TPhP,and EHDPP were favored to volatilize,TEP dominated the deposition,while TPrP and TNBP varied between volatilization and deposition.Atmospheric particle deposition fluxes ranged from 5 to 71 ng/m^(2)/day with an average of 17±15 ng/m^(2)/day.The input of∑OPEs to the entire South China Sea via atmospheric particle deposition was estimated to be 22±19 tons/year,while the net air−sea exchange fluxes of OPEs were volatilization from seawater to air with an average of 44±33 tons/year.This work suggests that air−sea exchange and atmospheric particle deposition are significant processes interfering with the transport of OPEs in the marine environment.展开更多
Three experiments for the simulation of typhoon Sinlaku (2002) over the western North Pacific are performed in this study by using the Canadian Mesoscale Compressible Community (MC2) atmospheric model. The objecti...Three experiments for the simulation of typhoon Sinlaku (2002) over the western North Pacific are performed in this study by using the Canadian Mesoscale Compressible Community (MC2) atmospheric model. The objective of these simulations is to investigate the air-sea interaction during extreme weather conditions, and to determine the sensitivity of the typhoon evolution to the sea surface temperature (SST) cooling induced by the typhoon. It is shown from the three experiments that the surface heat fluxes have a substantial influence on the slow-moving cyclone over its lifetime. When the SST in the East China coastal ocean becomes 1℃ cooler in the simulation, less latent heat and sensible heat fluxes from the underlying ocean to the cyclone tend to reduce the typhoon intensity. The cyclone is weakened by 7 hPa at the time of its peak intensity. The SST cooling also has impacts on the vertical structure of the typhoon by weakening the warm core and drying the eye wall. With a finer horizontal resolution of (1/6)° × (1/6)°, the model produces higher surface wind, and therefore more surface heat fluxes are emitted from the ocean surface to the cyclone, in the finer-resolution MC2 grid compared with the relatively lower resolution of 0.25° × 0.25° MC2 grid.展开更多
A regional air-sea coupled model, comprising the Regional Integrated Environment Model System (RIEMS) and the Princeton Ocean Model (POM) was developed to simulate summer climate features over East Asia in 2000. T...A regional air-sea coupled model, comprising the Regional Integrated Environment Model System (RIEMS) and the Princeton Ocean Model (POM) was developed to simulate summer climate features over East Asia in 2000. The sensitivity of the model's behavior to the coupling time interval (CTI), the causes of the sea surface temperature (SST) biases, and the role of air-sea interaction in the simulation of precipitation over China are investigated. Results show that the coupled model can basically produce the spatial pattern of SST, precipitation, and surface air temperature (SAT) with five different CTIs respectively. Also, using a CTI of 3, 6 or 12 hours tended to produce more successful simulations than if using 1 and 24 hours. Further analysis indicates that both a higher and lower coupling frequency result in larger model biases in air-sea heat flux exchanges, which might be responsible for the sensitivity of the coupled model's behavior to the CTI. Sensitivity experiments indicate that SST biases between the coupled and uncoupled POM occurring over the China coastal waters were due to the mismatch of the surface heat fluxes produced by the RIEMS with those required by the POM. In the coupled run, the air-sea feedbacks reduced the biases in surface heat fluxes, compared with the uncoupled RIEMS, consequently resulted in changes in thermal contrast over land and sea and led to a precipitation increase over South China and a decrease over North China. These results agree well observations in the summer of 2000.展开更多
The data analyses found at first that the air-sea system in the northwestern Pacific region has clear systematical quasi-decadal oscillation, such as the surface air temperature, the subtropical high activities over t...The data analyses found at first that the air-sea system in the northwestern Pacific region has clear systematical quasi-decadal oscillation, such as the surface air temperature, the subtropical high activities over the northwestern Pacific and the SSTA which has different time-scale features from the temporal variation with 3-4 years period of SSTA in the equatorial Pacific. In East Asia, the climate variations, such as the surface air temperature, the precipitation and the beginning date of Mei-yu in the Yangtze River basin, also have clear quasi-decadal oscillation. They can be regarded as the influences of quasi-decadal oscillation of air-sea system in the northwestern Pacific region.展开更多
The impact of surface sensible heating over the Tibetan Plateau (SHTP) on the western Pacific subtropical high (WPSH) with and without air-sea interaction was investigated in this study. Data analysis indicated th...The impact of surface sensible heating over the Tibetan Plateau (SHTP) on the western Pacific subtropical high (WPSH) with and without air-sea interaction was investigated in this study. Data analysis indicated that SHTP acts as a relatively independent factor in modulating the WPSH anomaly compared with ENSO events. Stronger spring SHTP is usually fol- lowed by an enhanced and westward extension of the WPSH in summer, and vice versa. Numerical experiments using both an AGCM and a CGCM confirmed that SHTP influences the large-scale circulation anomaly over the Pacific, which features a barotropic anticyclonic response over the northwestern Pacific and a cyclonic response to the south. Owing to different background circulation in spring and summer, such a response facilitates a subdued WPSH in spring but an en- hanced WPSH in summer. Moreover, the CGCM results showed that the equatorial low-level westerly at the south edge of the cyclonic anomaly brings about a warm SST anomaly (SSTA) in the equatorial central Pacific via surface warm advection. Subsequently, an atmospheric Rossby wave is stimulated to the northwest of the warm SSTA, which in turn enhances the at- mospheric dipole anomalies over the western Pacific. Therefore, the air-sea feedbacks involved tend to reinforce the effect of SHTP on the WPSH anomaly, and the role of SHTP on general circulation needs to be considered in a land-air-sea interaction framework.展开更多
It has long been recognized that the evolution of marine storms may be strongly affected by the flux transfer processes over the ocean. High winds in a storm can generate large amounts of spray, which can modify the t...It has long been recognized that the evolution of marine storms may be strongly affected by the flux transfer processes over the ocean. High winds in a storm can generate large amounts of spray, which can modify the transfer of momentum, heat, and moisture across the air-sea interface. However, the role of sea spray and air-sea processes in western Pacific typhoons has remained elusive. In this study, the impact of sea spray on air-sea fluxes and the evolution of a typhoon over the western Pacific is investigated using a coupled atmosphere-sea-spray modeling system. Through the case study of the recent Typhoon Fengshen from 2002, we found that: (1) Sea spray can cause a significant latent heat flux increase of up to 40% of the interfacial fluxes in the typhoon; (2) Taking into account the effects of sea spray, the intensity of the modeled typhoon can be increased by 30% in the 10-m wind speed, which may greatly improve estimates of storm maximum intensity and, to some extent, improve the simulations of overall storm structure in the atmospheric model; (3) The effects of sea spray are mainly focused over the high wind regions around the storm center and are mainly felt in the lower part of the troposphere.展开更多
The process of air—sea fresh water exchange is included successfully in the Global— Ocean—Atmosphere Land—System model developed at the State Key Laboratory of Atmospheric Sciences and Geophysical Fluid Dynamics (...The process of air—sea fresh water exchange is included successfully in the Global— Ocean—Atmosphere Land—System model developed at the State Key Laboratory of Atmospheric Sciences and Geophysical Fluid Dynamics (LASG). The results of the coupled integration show that the climate drift has been controlled successfully. Analyses on the responses of ocean circulation to the changes of surface fresh water or salinity forcing show that the ocean spin-up stage under flux condition for salinity is the key to the implementation of air-sea fresh water flux coupling. This study also demonstrates that the Modified—Monthly—Flux—Anomaly coupling scheme (MMFA) brought forward by Yu and Zhang (1998) is suitable not only for daily air—sea heat flux coupling but also for daily fresh water flux coupling. Key words Fresh water flux - Air-sea coupling - Thermohaline circulation This work was co-supported by the National Key Project (Grant No.96-908-02-03), the Excellent National Key Laboratory Research Project (Grant No.49823002) and Chinese Academy of Sciences (CAS) under grant “ Bai Ren Ji Hua? for “Validation of Coupled Climate Models”.展开更多
The annual, interannual and inter-decadal variability of convection intensity of South China Sea (SCS) summer monsoon and air-sea temperature difference in the tropical ocean is analyzed, and their relationship is dis...The annual, interannual and inter-decadal variability of convection intensity of South China Sea (SCS) summer monsoon and air-sea temperature difference in the tropical ocean is analyzed, and their relationship is discussed using two data sets of 48-a SODA (simple ocean data assimilation) and NCEP/NCAR. Analyses show that in wintertime Indian Ocean (WIO), springtime central tropical Pacific (SCTP) and summertime South China Sea-West Pacific (SSCSWP), air-sea temperature difference is significantly associated with the convection intensity of South China Sea summer monsoon. Correlation of the inter-decadal time scale (above 10 a) is higher and more stable. There is inter-decadal variability of correlation in scales less than 10 a and it is related with the air-sea temperature difference itself for corresponding waters. The inter-decadal variability of the convection intensity during the South China Sea summer monsoon is closely related to the inter-decadal variability of the general circulation of the atmosphere. Since the late period of the 1970s, in the lower troposphere, the cross-equatorial flow from the Southern Hemisphere has intensified. At the upper troposphere layer, the South Asian high and cross-equatorial flow from the Northern Hemisphere has intensified at the same time. Then the monsoon cell has also strengthened and resulted in the reinforcing of the convection of South China Sea summer monsoon.展开更多
The distributions of partial pressure of carbon dioxide (pCO2) in the surface waters of the Changjiang River Estuary and adjacent Hangzhou Bay were examined in the summer of 2010. Surface water pCO2 ranged from 751-...The distributions of partial pressure of carbon dioxide (pCO2) in the surface waters of the Changjiang River Estuary and adjacent Hangzhou Bay were examined in the summer of 2010. Surface water pCO2 ranged from 751-2 095/zatm (1 atm=101 325 Pa) in the inner estuary, 177-1 036/zatm in the outer estuary, and 498-1 166 μatm in Hangzhou Bay. Overall, surface pCO2 behaved conservatively during the estuary mixing. In the inner estuary, surface pCO2 was relatively high due to urbanized pollution and a high respiration rate. The lowest pCO2 was observed in the outer estuary, which was apparently induced by a phytoplankton bloom because the dissolved oxygen and chlorophyll a were very high. The Changjiang River Estuary was a significant source of atmospheric CO2 and the degassing fluxes were estimated as 0-230 mmol/(m2.d) [61 mmol/(m2.d) on average] in the inner estuary. In contrast, the outer estuary acted as a CO2 sink.展开更多
With the data observed from the Second SCS Air-Sea Flux Experiment on the Xisha air-sea flux research tower, the radiation budget, latent, sensible heat fluxes and net oceanic heat budgets were caculated before and af...With the data observed from the Second SCS Air-Sea Flux Experiment on the Xisha air-sea flux research tower, the radiation budget, latent, sensible heat fluxes and net oceanic heat budgets were caculated before and after summer monsoon onset. It is discovered that, after summer monsoon onset, there are considerable changes in air-sea fluxes, especially in latent heat fluxes and net oceanic heat budget. Furthermore, the analyzed results of five synoptic stages are compared. And the characteristics of the flux transfer during different stages around onset of South China Sea monsoon are discussed. The flux change shows that there is an oceanic heat accumulating process during the pre-onset and the break period, as same as oceanic heat losing process during the onset period. Moreover, latent fluxes, the water vapor moving to the continent, even the rainfall appearance in Chinese Mainland also can be influenced by southwester. Comparing Xisha fluxes with those obtained from the Indian Ocean and the western Pacific Ocean, their differences may be observed. It is the reason why SSTs can keep stable over the South China Sea while they decrease quickly over the Arabian Sea and the Bay of Bengal after monsoon onset.展开更多
This paper delineates the coupled and principal pattrns of sea surface temperture (SST) and surface wind near the South China Sea (SCS), and discusses the mechanisms of air-sea coupling near the SCS and their asspcoia...This paper delineates the coupled and principal pattrns of sea surface temperture (SST) and surface wind near the South China Sea (SCS), and discusses the mechanisms of air-sea coupling near the SCS and their asspcoiation with the Asian monsoon. Singular value decomposition (SVD) and single field principal component analysis (PCA) are applied to the so and wind anomalies from the 1979 - 1995 NCEP/NCAR reanalysis data.The leading SVD mode explains a predominant amount of squared covariance between the SST and zonal or meridional wind. During winte, the meridional wind’s relation to the SST is betterr than the relation of zonal wind to ase. Despite the large magnitude of the squared covariance between SST and zonalor meridional wind, the spatial patterns of the first mode of SVD between the SST and meridional wind are similar. They both exhibit ellipe-shaped variance with the center near the SCS and a northeast-southwest oriented main axis. The spatial patterne of the leading mode of SVD between the SST and zonal wind are also similar to a certain degree. The zonal wind is not as closely correlated to the SST as the meridional wind is. These results suggest that the meridional wind and SST are stronly coupled during the winter season, and that there is a certain coupled action system in the SCS.展开更多
State-of-the-art climate models have long-standing intrinsic biases that limit their simulation and projection capabilities. Significantly weak ENSO asymmetry and weakly nonlinear air-sea interaction over the tropical...State-of-the-art climate models have long-standing intrinsic biases that limit their simulation and projection capabilities. Significantly weak ENSO asymmetry and weakly nonlinear air-sea interaction over the tropical Pacific was found in CMIP5 (Coupled Model Intercomparison Project, Phase 5) climate models compared with observation. The results suggest that a weak nonlinear air-sea interaction may play a role in the weak ENSO asymmetry. Moreover, a weak nonlinearity in air-sea interaction in the models may be associated with the biases in the mean climate--the cold biases in the equatorial central Pacific. The excessive cold tongue bias pushes the deep convection far west to the western Pacific warm pool region and suppresses its development in the central equatorial Pacific. The deep convection has difficulties in further moving to the eastern equatorial Pacific, especially during extreme El Nifio events, which confines the westerly wind anomaly to the western Pacific. This weakens the eastern Pacific El Nifio events, especially the extreme E1 Nifio events, and thus leads to the weakened ENSO asymmetry in climate models. An accurate mean state structure (especially a realistic cold tongue and deep convection) is critical to reproducing ENSO events in climate models. Our evaluation also revealed that ENSO statistics in CMIP5 climate models are slightly improved compared with those of CMIP3. The weak ENSO asymmetry in CMIP5 is closer to the observation. It is more evident in CMIP5 that strong ENSO activities are usually accompanied by strong ENSO asymmetry, and the diversity of ENSO amplitude is reduced.展开更多
A singular value decomposition (SVD) analysis is carried out to reveal the relationship between the interannual variation of track and intensity of the western North Pacific tropical cyclones (WNPTCs) in the tropi...A singular value decomposition (SVD) analysis is carried out to reveal the relationship between the interannual variation of track and intensity of the western North Pacific tropical cyclones (WNPTCs) in the tropical cyclone (TC) active season (July–November) and the global net air-sea heat flux (Q net ) in the preceding season (April–June). For this purpose, a tropical cyclone track and intensity function (TIF) is defined by a combination of accumulated cyclone energy (ACE) index and a cyclone track density function. The SVD analysis reveals that the first mode is responsible for the positive correlation between the upward heat flux in the tropical central Pacific and the increased activity of western North Pacific (WNP) TIF, the second mode for the positive correlation between the upward heat flux in the North Indian Ocean and the northeastward track shift of WNPTCs and the third mode for the negative correlation between the upward heat flux in mid-latitude central Pacific and the northwest displacement of the WNP TC-active center. This suggests that Q net anomalies in some key regions have a substantial remote impact on the WNP TC activity.展开更多
This study examined the regional air sea coupled interaction in the South China Sea (SCS), based on the 1979-1995 NCEP/NCAR reanalysis data of sea surface temperature (SST) and meridional wind (V component). Singular ...This study examined the regional air sea coupled interaction in the South China Sea (SCS), based on the 1979-1995 NCEP/NCAR reanalysis data of sea surface temperature (SST) and meridional wind (V component). Singular value decomposition (SVD) and single field principal component analysis (PCA) were employed to analyse the SST and V anomalies and compare the results with each other. It was found that the leading mode of SVD explained a predominant amount of squared covariance between the SST and meridional wind V, and that the time series expansion coefficients of the first mode between SST and V from PCA and SVD resembled very much each other. This infers that the meridional wind, as an indicator of Asian monsoon, is closely related with the SST through the air sea interaction in the SCS. The spatial patterns of the first mode of SST and V exhibit ellipse shaped variance in the SCS center and a NE SW oriented main axis, which are much similar to those in winter season. These results show that the most active center for both V and SST is in the SCS, which suggests that a regional air sea coupled oscillation possibly exists there for the whole year and is noticeable especially during the winter season. So the SCS is a very important region for the forming of the Asian Monsoon and the climate of the west Pacific.展开更多
A simple air-sea coupled model, the atmospheric general circulation model (AGCM) of the National Centers for Environmental Prediction coupled to a mixed-layer slab ocean model, is employed to investigate the impact ...A simple air-sea coupled model, the atmospheric general circulation model (AGCM) of the National Centers for Environmental Prediction coupled to a mixed-layer slab ocean model, is employed to investigate the impact of air-sea coupling on the signals of the Atlantic Multidecadal Oscillation (AMO). A regional coupling strategy is applied, in which coupling is switched off in the extratropical North Atlantic Ocean but switched on in the open oceans elsewhere. The coupled model is forced with warm-phase AMO SST anomalies, and the modeled responses are compared with those from parallel uncoupled AGCM experiments with the same SST forcing. The results suggest that the regionally coupled responses not only resemble the AGCM simulation, but also have a stronger intensity. In comparison, the coupled responses bear greater similarity to the observational composite anomaly. Thus, air-sea coupling enhances the responses of the East Asian winter climate to the AMO. To determine the mechanism responsible for the coupling amplification, an additional set of AGCM experiments, forced with the AMO-induced tropical SST anomalies, is conducted. The SST anomalies are extracted from the simulated AMO-induced SST response in the regionally coupled model. The results suggest that the SST anomalies contribute to the coupling amplification. Thus, tropical air-sea coupling feedback tends to enhance the responses of the East Asian winter climate to the AMO.展开更多
The performance of a regional air-sea coupled model, comprising the Regional Integrated Environment Model System (RIEMS) and the Princeton Ocean Model (POM), in simulating the seasonal and intraseasonal variations...The performance of a regional air-sea coupled model, comprising the Regional Integrated Environment Model System (RIEMS) and the Princeton Ocean Model (POM), in simulating the seasonal and intraseasonal variations of East Asian summer monsoon (EASM) rainfall was investigated. Through comparisons of the model results among the coupled model, the uncoupled RIEMS, and observations, the impact of air-sea coupling on simulating the EASM was also evaluated. Results showed that the regional air sea coupled climate model performed better in simulating the spatial pattern of the precipitation climatology and produced more realistic variations of the EASM rainfall in terms of its amplitude and principal EOF modes. The coupled model also showed greater skill than the uncoupled RIEMS in reproducing the principal features of climatological intraseasonal oscillation (CISO) of EASM rainfall, including its dominant period, intensity, and northward propagation. Further analysis indicated that the improvements in the simulation of the EASM rainfall climatology and its seasonal variation in the coupled model were due to better simulation of the western North Pacific Subtropical High, while the improvements of CISO simulation were owing to the realistic phase relationship between the intraseasonal convection and the underlying SST resulting from the air-sea coupling.展开更多
In this study a coupled air-sea-wave model system, containing the model components of GRAPES-TCM, ECOM-si and WAVEWATCH III, is established based on an air-sea coupled model. The changes of wave state and the effects ...In this study a coupled air-sea-wave model system, containing the model components of GRAPES-TCM, ECOM-si and WAVEWATCH III, is established based on an air-sea coupled model. The changes of wave state and the effects of sea spray are both considered. Using the complex air-sea-wave model, a set of idealized simulations was applied to investigate the effects of air-sea-wave interaction in the upper ocean. Results show that air-wave coupling can strengthen tropical cyclones while air-sea coupling can weaken them; and air-sea-wave coupling is comparable to that of air-sea coupling, as the intensity is almost unchanged with the wave model coupled to the air-sea coupled model.The mixing by vertical advection is strengthened if the wave effect is considered, and causes much more obvious sea surface temperature(SST) decreases in the upper ocean in the air-sea coupled model. Air-wave coupling strengthens the air-sea heat exchange, while the thermodynamic coupling between the atmosphere and ocean weakens the air-sea heat exchange: the air-sea-wave coupling is the result of their balance. The wave field distribution characteristic is determined by the wind field. Experiments are also conducted to simulate ocean responses to different mixed layer depths.With increasing depth of the initial mixed layer, the decrease of SST weakens, but the temperature decrease of deeper layers is enhanced and the loss of heat in the upper ocean is increased. The significant wave height is larger when the initial mixed layer depth increases.展开更多
Collaboration of interannual variabilities and the climate mean state determines the type of El Nio. Recent studies highlight the impact of a La Nia-like mean state change, which acts to suppress the convection an...Collaboration of interannual variabilities and the climate mean state determines the type of El Nio. Recent studies highlight the impact of a La Nia-like mean state change, which acts to suppress the convection and low-level convergence over the central Pacific, on the predominance of central Pacific(CP) El Nio in the most recent decade. However, how interannual variabilities affect the climate mean state has been less thoroughly investigated. Using a linear shallow-water model, the effect of decadal changes of air-sea interaction on the two types of El Nio and the climate mean state over the tropical Pacific is examined. It is demonstrated that the predominance of the eastern Pacific(EP) and CP El Nio is dominated mainly by relationships between anomalous wind stresses and sea surface temperature(SST). Furthermore, changes between air-sea interactions from 1980–98 to 1999–2011 prompted the generation of the La Nialike pattern, which is similar to the background change in the most recent decade.展开更多
The dynamical features of air-sea coupling waves and their stabilities in a simple coupled air-sea model in the tropics have been studied with respect to interaction occurring among different types of the free waves i...The dynamical features of air-sea coupling waves and their stabilities in a simple coupled air-sea model in the tropics have been studied with respect to interaction occurring among different types of the free waves in the o-cean and in the atmosphere. It is pointed out that there exist a stable and an unstable air-sea interaction modes in the tropical coupled system , respectively. The propagation of the unstable mode relies greatly on the zonal space scale, i. e. only for wave length ranging from 5 000 km to 10 000 km can the disturbance unstably move slowly eastward. The waves that slowly propagate unstably eastward agree well with the observational facts. Finally,it is also proposed that the interaction between Kelvin wave in one medium and Rossby wave in another medium is a necessary condition for the occurrence of destabilization of the coupled air-sea system in the tropics.展开更多
基金supported by the Federal Ministry of Education and Research of Germany(03F0786C and 03G0269)the Hainan Provincial Natural Science Foundation of China(No.422CXTD533)+1 种基金L.M.gratefully acknowledges the China Scholarship Council for financial support.Funding for the cruise was received by J.J.W.(03G0269)the Federal Ministry of Education and Research of Germany.
文摘Organophosphate esters(OPEs)have become one group of chemicals with emerging concern in the marine environment.In this work,we investigated OPEs in the air and seawater of the South China Sea in summer 2019.The concentrations of∑_(10)OPEs in the atmosphere ranged from 66 to 550 pg/m^(3),with TCIPP,TNBP,TPhP,and TEP predominating in the air.The total dissolved OPE concentrations(∑_(10)OPEs without TEP)measured in high-volume water samples ranged from 300 to 3600 pg/L,with a mean concentration of 1180±910 pg/L.TEP was measured with liquid−liquid extraction(LLE),and it showed the highest concentration(average 2000±1450 pg/L)among the selected OPEs.Total suspended matter associated OPEs accounted for less than 4.7%of the sum of OPE concentrations in seawater.Fugacity fractions and air−sea exchange fluxes showed that TCEP,TCIPP,TIBP,TEHP,TPhP,and EHDPP were favored to volatilize,TEP dominated the deposition,while TPrP and TNBP varied between volatilization and deposition.Atmospheric particle deposition fluxes ranged from 5 to 71 ng/m^(2)/day with an average of 17±15 ng/m^(2)/day.The input of∑OPEs to the entire South China Sea via atmospheric particle deposition was estimated to be 22±19 tons/year,while the net air−sea exchange fluxes of OPEs were volatilization from seawater to air with an average of 44±33 tons/year.This work suggests that air−sea exchange and atmospheric particle deposition are significant processes interfering with the transport of OPEs in the marine environment.
文摘Three experiments for the simulation of typhoon Sinlaku (2002) over the western North Pacific are performed in this study by using the Canadian Mesoscale Compressible Community (MC2) atmospheric model. The objective of these simulations is to investigate the air-sea interaction during extreme weather conditions, and to determine the sensitivity of the typhoon evolution to the sea surface temperature (SST) cooling induced by the typhoon. It is shown from the three experiments that the surface heat fluxes have a substantial influence on the slow-moving cyclone over its lifetime. When the SST in the East China coastal ocean becomes 1℃ cooler in the simulation, less latent heat and sensible heat fluxes from the underlying ocean to the cyclone tend to reduce the typhoon intensity. The cyclone is weakened by 7 hPa at the time of its peak intensity. The SST cooling also has impacts on the vertical structure of the typhoon by weakening the warm core and drying the eye wall. With a finer horizontal resolution of (1/6)° × (1/6)°, the model produces higher surface wind, and therefore more surface heat fluxes are emitted from the ocean surface to the cyclone, in the finer-resolution MC2 grid compared with the relatively lower resolution of 0.25° × 0.25° MC2 grid.
基金supported by the National Basic Research Program under Grand No.2006CB400506
文摘A regional air-sea coupled model, comprising the Regional Integrated Environment Model System (RIEMS) and the Princeton Ocean Model (POM) was developed to simulate summer climate features over East Asia in 2000. The sensitivity of the model's behavior to the coupling time interval (CTI), the causes of the sea surface temperature (SST) biases, and the role of air-sea interaction in the simulation of precipitation over China are investigated. Results show that the coupled model can basically produce the spatial pattern of SST, precipitation, and surface air temperature (SAT) with five different CTIs respectively. Also, using a CTI of 3, 6 or 12 hours tended to produce more successful simulations than if using 1 and 24 hours. Further analysis indicates that both a higher and lower coupling frequency result in larger model biases in air-sea heat flux exchanges, which might be responsible for the sensitivity of the coupled model's behavior to the CTI. Sensitivity experiments indicate that SST biases between the coupled and uncoupled POM occurring over the China coastal waters were due to the mismatch of the surface heat fluxes produced by the RIEMS with those required by the POM. In the coupled run, the air-sea feedbacks reduced the biases in surface heat fluxes, compared with the uncoupled RIEMS, consequently resulted in changes in thermal contrast over land and sea and led to a precipitation increase over South China and a decrease over North China. These results agree well observations in the summer of 2000.
文摘The data analyses found at first that the air-sea system in the northwestern Pacific region has clear systematical quasi-decadal oscillation, such as the surface air temperature, the subtropical high activities over the northwestern Pacific and the SSTA which has different time-scale features from the temporal variation with 3-4 years period of SSTA in the equatorial Pacific. In East Asia, the climate variations, such as the surface air temperature, the precipitation and the beginning date of Mei-yu in the Yangtze River basin, also have clear quasi-decadal oscillation. They can be regarded as the influences of quasi-decadal oscillation of air-sea system in the northwestern Pacific region.
基金supported jointly by the National Natural Science Foundation of China(Grant No.91337216)the Special Fund for Public Welfare Industry(Meteorology),administered by the Chinese Ministry of Finance and the Ministry of Science and Technology(Grant No.GYHY201406001)the CAS XDA(Grant No.11010402)
文摘The impact of surface sensible heating over the Tibetan Plateau (SHTP) on the western Pacific subtropical high (WPSH) with and without air-sea interaction was investigated in this study. Data analysis indicated that SHTP acts as a relatively independent factor in modulating the WPSH anomaly compared with ENSO events. Stronger spring SHTP is usually fol- lowed by an enhanced and westward extension of the WPSH in summer, and vice versa. Numerical experiments using both an AGCM and a CGCM confirmed that SHTP influences the large-scale circulation anomaly over the Pacific, which features a barotropic anticyclonic response over the northwestern Pacific and a cyclonic response to the south. Owing to different background circulation in spring and summer, such a response facilitates a subdued WPSH in spring but an en- hanced WPSH in summer. Moreover, the CGCM results showed that the equatorial low-level westerly at the south edge of the cyclonic anomaly brings about a warm SST anomaly (SSTA) in the equatorial central Pacific via surface warm advection. Subsequently, an atmospheric Rossby wave is stimulated to the northwest of the warm SSTA, which in turn enhances the at- mospheric dipole anomalies over the western Pacific. Therefore, the air-sea feedbacks involved tend to reinforce the effect of SHTP on the WPSH anomaly, and the role of SHTP on general circulation needs to be considered in a land-air-sea interaction framework.
文摘It has long been recognized that the evolution of marine storms may be strongly affected by the flux transfer processes over the ocean. High winds in a storm can generate large amounts of spray, which can modify the transfer of momentum, heat, and moisture across the air-sea interface. However, the role of sea spray and air-sea processes in western Pacific typhoons has remained elusive. In this study, the impact of sea spray on air-sea fluxes and the evolution of a typhoon over the western Pacific is investigated using a coupled atmosphere-sea-spray modeling system. Through the case study of the recent Typhoon Fengshen from 2002, we found that: (1) Sea spray can cause a significant latent heat flux increase of up to 40% of the interfacial fluxes in the typhoon; (2) Taking into account the effects of sea spray, the intensity of the modeled typhoon can be increased by 30% in the 10-m wind speed, which may greatly improve estimates of storm maximum intensity and, to some extent, improve the simulations of overall storm structure in the atmospheric model; (3) The effects of sea spray are mainly focused over the high wind regions around the storm center and are mainly felt in the lower part of the troposphere.
文摘The process of air—sea fresh water exchange is included successfully in the Global— Ocean—Atmosphere Land—System model developed at the State Key Laboratory of Atmospheric Sciences and Geophysical Fluid Dynamics (LASG). The results of the coupled integration show that the climate drift has been controlled successfully. Analyses on the responses of ocean circulation to the changes of surface fresh water or salinity forcing show that the ocean spin-up stage under flux condition for salinity is the key to the implementation of air-sea fresh water flux coupling. This study also demonstrates that the Modified—Monthly—Flux—Anomaly coupling scheme (MMFA) brought forward by Yu and Zhang (1998) is suitable not only for daily air—sea heat flux coupling but also for daily fresh water flux coupling. Key words Fresh water flux - Air-sea coupling - Thermohaline circulation This work was co-supported by the National Key Project (Grant No.96-908-02-03), the Excellent National Key Laboratory Research Project (Grant No.49823002) and Chinese Academy of Sciences (CAS) under grant “ Bai Ren Ji Hua? for “Validation of Coupled Climate Models”.
基金This study was supported by the project of the National Natural Science Foundation of China"Response of inter-decadal variability of South China Sea summer monsoon to the whole globe variability”under contract number 9021l010“Interannual to interdecadal variability in circulation in the tropical Pa-cific Ocean”under contract number 40136010.
文摘The annual, interannual and inter-decadal variability of convection intensity of South China Sea (SCS) summer monsoon and air-sea temperature difference in the tropical ocean is analyzed, and their relationship is discussed using two data sets of 48-a SODA (simple ocean data assimilation) and NCEP/NCAR. Analyses show that in wintertime Indian Ocean (WIO), springtime central tropical Pacific (SCTP) and summertime South China Sea-West Pacific (SSCSWP), air-sea temperature difference is significantly associated with the convection intensity of South China Sea summer monsoon. Correlation of the inter-decadal time scale (above 10 a) is higher and more stable. There is inter-decadal variability of correlation in scales less than 10 a and it is related with the air-sea temperature difference itself for corresponding waters. The inter-decadal variability of the convection intensity during the South China Sea summer monsoon is closely related to the inter-decadal variability of the general circulation of the atmosphere. Since the late period of the 1970s, in the lower troposphere, the cross-equatorial flow from the Southern Hemisphere has intensified. At the upper troposphere layer, the South Asian high and cross-equatorial flow from the Northern Hemisphere has intensified at the same time. Then the monsoon cell has also strengthened and resulted in the reinforcing of the convection of South China Sea summer monsoon.
基金The Marine Public Welfare Project of China under contract Nos200805029,200905012,200905025,and 201005034the Scientific Research Fund of the Second Institute of Oceanography,SOA under contract Nos JG0821 and JG1021
文摘The distributions of partial pressure of carbon dioxide (pCO2) in the surface waters of the Changjiang River Estuary and adjacent Hangzhou Bay were examined in the summer of 2010. Surface water pCO2 ranged from 751-2 095/zatm (1 atm=101 325 Pa) in the inner estuary, 177-1 036/zatm in the outer estuary, and 498-1 166 μatm in Hangzhou Bay. Overall, surface pCO2 behaved conservatively during the estuary mixing. In the inner estuary, surface pCO2 was relatively high due to urbanized pollution and a high respiration rate. The lowest pCO2 was observed in the outer estuary, which was apparently induced by a phytoplankton bloom because the dissolved oxygen and chlorophyll a were very high. The Changjiang River Estuary was a significant source of atmospheric CO2 and the degassing fluxes were estimated as 0-230 mmol/(m2.d) [61 mmol/(m2.d) on average] in the inner estuary. In contrast, the outer estuary acted as a CO2 sink.
基金National Natural Science Foundation of China under contract No. 40075003The Prior Study of State Key Project for Basic Research "East Asian Monsoon Experiment".
文摘With the data observed from the Second SCS Air-Sea Flux Experiment on the Xisha air-sea flux research tower, the radiation budget, latent, sensible heat fluxes and net oceanic heat budgets were caculated before and after summer monsoon onset. It is discovered that, after summer monsoon onset, there are considerable changes in air-sea fluxes, especially in latent heat fluxes and net oceanic heat budget. Furthermore, the analyzed results of five synoptic stages are compared. And the characteristics of the flux transfer during different stages around onset of South China Sea monsoon are discussed. The flux change shows that there is an oceanic heat accumulating process during the pre-onset and the break period, as same as oceanic heat losing process during the onset period. Moreover, latent fluxes, the water vapor moving to the continent, even the rainfall appearance in Chinese Mainland also can be influenced by southwester. Comparing Xisha fluxes with those obtained from the Indian Ocean and the western Pacific Ocean, their differences may be observed. It is the reason why SSTs can keep stable over the South China Sea while they decrease quickly over the Arabian Sea and the Bay of Bengal after monsoon onset.
文摘This paper delineates the coupled and principal pattrns of sea surface temperture (SST) and surface wind near the South China Sea (SCS), and discusses the mechanisms of air-sea coupling near the SCS and their asspcoiation with the Asian monsoon. Singular value decomposition (SVD) and single field principal component analysis (PCA) are applied to the so and wind anomalies from the 1979 - 1995 NCEP/NCAR reanalysis data.The leading SVD mode explains a predominant amount of squared covariance between the SST and zonal or meridional wind. During winte, the meridional wind’s relation to the SST is betterr than the relation of zonal wind to ase. Despite the large magnitude of the squared covariance between SST and zonalor meridional wind, the spatial patterns of the first mode of SVD between the SST and meridional wind are similar. They both exhibit ellipe-shaped variance with the center near the SCS and a northeast-southwest oriented main axis. The spatial patterne of the leading mode of SVD between the SST and zonal wind are also similar to a certain degree. The zonal wind is not as closely correlated to the SST as the meridional wind is. These results suggest that the meridional wind and SST are stronly coupled during the winter season, and that there is a certain coupled action system in the SCS.
基金supported by the National Basic Research Program of China under the project“Structures,Variability and Climatic Impacts of Ocean Circulation and the Warm Pool in the Tropical Pacific Ocean”(Grant No.2012CB417401)the Strategic Priority Research Program–Climate Change:Carbon Budget and Related Issues,of the Chinese Academy of Sciences(Grant No.XDA05110302)+2 种基金the China Postdoctoral Science Foundation(Grant No.2012M521378)the Large-scale and Climate Dynamics Program of the U.S.National Science Foundation(AGS 0553111 and AGS 0852329)the Office of Global Programs of NOAA
文摘State-of-the-art climate models have long-standing intrinsic biases that limit their simulation and projection capabilities. Significantly weak ENSO asymmetry and weakly nonlinear air-sea interaction over the tropical Pacific was found in CMIP5 (Coupled Model Intercomparison Project, Phase 5) climate models compared with observation. The results suggest that a weak nonlinear air-sea interaction may play a role in the weak ENSO asymmetry. Moreover, a weak nonlinearity in air-sea interaction in the models may be associated with the biases in the mean climate--the cold biases in the equatorial central Pacific. The excessive cold tongue bias pushes the deep convection far west to the western Pacific warm pool region and suppresses its development in the central equatorial Pacific. The deep convection has difficulties in further moving to the eastern equatorial Pacific, especially during extreme El Nifio events, which confines the westerly wind anomaly to the western Pacific. This weakens the eastern Pacific El Nifio events, especially the extreme E1 Nifio events, and thus leads to the weakened ENSO asymmetry in climate models. An accurate mean state structure (especially a realistic cold tongue and deep convection) is critical to reproducing ENSO events in climate models. Our evaluation also revealed that ENSO statistics in CMIP5 climate models are slightly improved compared with those of CMIP3. The weak ENSO asymmetry in CMIP5 is closer to the observation. It is more evident in CMIP5 that strong ENSO activities are usually accompanied by strong ENSO asymmetry, and the diversity of ENSO amplitude is reduced.
基金The National Key Basic Research Program of China under Grant No.2009CB421404the National Natural Science Foundation of China-Regional Cooperation Project under Grant No.40921160379+1 种基金the National Natural Science foundation of China under Grant No.40730951the Fundamental Research Funds for the Central Universities under Grant No.11lgjc10
文摘A singular value decomposition (SVD) analysis is carried out to reveal the relationship between the interannual variation of track and intensity of the western North Pacific tropical cyclones (WNPTCs) in the tropical cyclone (TC) active season (July–November) and the global net air-sea heat flux (Q net ) in the preceding season (April–June). For this purpose, a tropical cyclone track and intensity function (TIF) is defined by a combination of accumulated cyclone energy (ACE) index and a cyclone track density function. The SVD analysis reveals that the first mode is responsible for the positive correlation between the upward heat flux in the tropical central Pacific and the increased activity of western North Pacific (WNP) TIF, the second mode for the positive correlation between the upward heat flux in the North Indian Ocean and the northeastward track shift of WNPTCs and the third mode for the negative correlation between the upward heat flux in mid-latitude central Pacific and the northwest displacement of the WNP TC-active center. This suggests that Q net anomalies in some key regions have a substantial remote impact on the WNP TC activity.
文摘This study examined the regional air sea coupled interaction in the South China Sea (SCS), based on the 1979-1995 NCEP/NCAR reanalysis data of sea surface temperature (SST) and meridional wind (V component). Singular value decomposition (SVD) and single field principal component analysis (PCA) were employed to analyse the SST and V anomalies and compare the results with each other. It was found that the leading mode of SVD explained a predominant amount of squared covariance between the SST and meridional wind V, and that the time series expansion coefficients of the first mode between SST and V from PCA and SVD resembled very much each other. This infers that the meridional wind, as an indicator of Asian monsoon, is closely related with the SST through the air sea interaction in the SCS. The spatial patterns of the first mode of SST and V exhibit ellipse shaped variance in the SCS center and a NE SW oriented main axis, which are much similar to those in winter season. These results show that the most active center for both V and SST is in the SCS, which suggests that a regional air sea coupled oscillation possibly exists there for the whole year and is noticeable especially during the winter season. So the SCS is a very important region for the forming of the Asian Monsoon and the climate of the west Pacific.
基金supported by the National Key R&D Program for Developing Basic Sciences [grant numbers2016YFC1401401 and 2016YFC1401601]the National Natural Science Foundation of China [grant numbers41376026 and 41576025]
基金supported by the strategic project of the Chinese Academy of Sciences(Grant No.XDA11010406)the National Natural Science Foundation of China (Grant Nos.41375085 and 41421004)
文摘A simple air-sea coupled model, the atmospheric general circulation model (AGCM) of the National Centers for Environmental Prediction coupled to a mixed-layer slab ocean model, is employed to investigate the impact of air-sea coupling on the signals of the Atlantic Multidecadal Oscillation (AMO). A regional coupling strategy is applied, in which coupling is switched off in the extratropical North Atlantic Ocean but switched on in the open oceans elsewhere. The coupled model is forced with warm-phase AMO SST anomalies, and the modeled responses are compared with those from parallel uncoupled AGCM experiments with the same SST forcing. The results suggest that the regionally coupled responses not only resemble the AGCM simulation, but also have a stronger intensity. In comparison, the coupled responses bear greater similarity to the observational composite anomaly. Thus, air-sea coupling enhances the responses of the East Asian winter climate to the AMO. To determine the mechanism responsible for the coupling amplification, an additional set of AGCM experiments, forced with the AMO-induced tropical SST anomalies, is conducted. The SST anomalies are extracted from the simulated AMO-induced SST response in the regionally coupled model. The results suggest that the SST anomalies contribute to the coupling amplification. Thus, tropical air-sea coupling feedback tends to enhance the responses of the East Asian winter climate to the AMO.
基金the National Natural Science Foundation of China,the National Basic Research Program of China (973 Program)
文摘The performance of a regional air-sea coupled model, comprising the Regional Integrated Environment Model System (RIEMS) and the Princeton Ocean Model (POM), in simulating the seasonal and intraseasonal variations of East Asian summer monsoon (EASM) rainfall was investigated. Through comparisons of the model results among the coupled model, the uncoupled RIEMS, and observations, the impact of air-sea coupling on simulating the EASM was also evaluated. Results showed that the regional air sea coupled climate model performed better in simulating the spatial pattern of the precipitation climatology and produced more realistic variations of the EASM rainfall in terms of its amplitude and principal EOF modes. The coupled model also showed greater skill than the uncoupled RIEMS in reproducing the principal features of climatological intraseasonal oscillation (CISO) of EASM rainfall, including its dominant period, intensity, and northward propagation. Further analysis indicated that the improvements in the simulation of the EASM rainfall climatology and its seasonal variation in the coupled model were due to better simulation of the western North Pacific Subtropical High, while the improvements of CISO simulation were owing to the realistic phase relationship between the intraseasonal convection and the underlying SST resulting from the air-sea coupling.
基金"973"Project(2013CB430305)Special Scientific Research Fund of Meteorological Public Welfare of China(GYHY201206006,GYHY 201106004)Shanghai Meteorological Service(TD201403)
文摘In this study a coupled air-sea-wave model system, containing the model components of GRAPES-TCM, ECOM-si and WAVEWATCH III, is established based on an air-sea coupled model. The changes of wave state and the effects of sea spray are both considered. Using the complex air-sea-wave model, a set of idealized simulations was applied to investigate the effects of air-sea-wave interaction in the upper ocean. Results show that air-wave coupling can strengthen tropical cyclones while air-sea coupling can weaken them; and air-sea-wave coupling is comparable to that of air-sea coupling, as the intensity is almost unchanged with the wave model coupled to the air-sea coupled model.The mixing by vertical advection is strengthened if the wave effect is considered, and causes much more obvious sea surface temperature(SST) decreases in the upper ocean in the air-sea coupled model. Air-wave coupling strengthens the air-sea heat exchange, while the thermodynamic coupling between the atmosphere and ocean weakens the air-sea heat exchange: the air-sea-wave coupling is the result of their balance. The wave field distribution characteristic is determined by the wind field. Experiments are also conducted to simulate ocean responses to different mixed layer depths.With increasing depth of the initial mixed layer, the decrease of SST weakens, but the temperature decrease of deeper layers is enhanced and the loss of heat in the upper ocean is increased. The significant wave height is larger when the initial mixed layer depth increases.
基金supported by the National Program for Support of Top-notch Young Professionals,the National Basic Research Program of China (Grant Nos. 2012CB955202 and 2012CB417404)"Western Pacific Ocean System: Structure, Dynamics, and Consequences" of the Chinese Academy Sciences (WPOS+1 种基金 Grant No. XDA10010405)the National Natural Science Foundation of China (Grant No. 41176014)
文摘Collaboration of interannual variabilities and the climate mean state determines the type of El Nio. Recent studies highlight the impact of a La Nia-like mean state change, which acts to suppress the convection and low-level convergence over the central Pacific, on the predominance of central Pacific(CP) El Nio in the most recent decade. However, how interannual variabilities affect the climate mean state has been less thoroughly investigated. Using a linear shallow-water model, the effect of decadal changes of air-sea interaction on the two types of El Nio and the climate mean state over the tropical Pacific is examined. It is demonstrated that the predominance of the eastern Pacific(EP) and CP El Nio is dominated mainly by relationships between anomalous wind stresses and sea surface temperature(SST). Furthermore, changes between air-sea interactions from 1980–98 to 1999–2011 prompted the generation of the La Nialike pattern, which is similar to the background change in the most recent decade.
文摘The dynamical features of air-sea coupling waves and their stabilities in a simple coupled air-sea model in the tropics have been studied with respect to interaction occurring among different types of the free waves in the o-cean and in the atmosphere. It is pointed out that there exist a stable and an unstable air-sea interaction modes in the tropical coupled system , respectively. The propagation of the unstable mode relies greatly on the zonal space scale, i. e. only for wave length ranging from 5 000 km to 10 000 km can the disturbance unstably move slowly eastward. The waves that slowly propagate unstably eastward agree well with the observational facts. Finally,it is also proposed that the interaction between Kelvin wave in one medium and Rossby wave in another medium is a necessary condition for the occurrence of destabilization of the coupled air-sea system in the tropics.