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1.
The trends of the sea surface temperature(SST) and SST fronts in the South China Sea(SCS) are analyzed during2003–2017 using high-resolution satellite data. The linear trend of the basin averaged SST is 0.31°C per decade,with the strongest warming identified in southeastern Vietnam. Although the rate of warming is comparable in summer and winter for the entire basin, the corresponding spatial patterns of the linear trend are substantially different between them. The SST trend to the west of the Luzon Strait is characterized by rapid warming in summer, exceeding approximately 0.6°C per decade, but the trend is insignificant in winter. The strongest warming trend occurs in the southeast of Vietnam in winter, with much less pronounced warming in summer. A positive trend of SST fronts is identified for the coast of China and is associated with increasing wind stress. The increasing trend of SST fronts is also found in the east of Vietnam. Large-scale circulation, such as El Ni?o, can influence the trends of the SST and SST fronts. A significant correlation is found between the SST anomaly and Ni?o3.4 index, and the ENSO signal leads by eight months. The basin averaged SST linear trends increase after the El Ni?o event(2009–2010), which is, at least, due to the rapid warming rate causing by the enhanced northeasterly wind. Peaks of positive anomalous SST and negatively anomalous SST fronts are found to co-occur with the strong El Ni?o events.  相似文献   

2.
The global surface temperature change since the mid-19th century has caused general concern and intensive study. However, long-term changes in the marginal seas, including the seas east of China, are not well understood because long-term observations are sparse and, even when they exist, they are over limited areas. Preliminary results on the long-term variability of sea surface temperature (SST) in summer and winter in the seas east of China during the period of 1957-2001 are reported using the Ocean Science Database of Institute of Oceanology, Chinese Academy of Sciences, the coastal hydrological station in situ and satellite data. The results show well-defined warming trends in the study area. However warming and cooling trends vary from decade to decade, with steady and rapid warming trends after the 1980s and complicated spatial patterns. The distribution of SST variation is intricate and more blurred in the areas far away from the Kuroshio system. Both historical and satellite data sets show significant warming trends after 1985. The warming trends are larger and spread to wider areas in winter than in summer, which means decrease in the seasonal cycle of SST probably linked with recently observed increase of the tropical zooplankton species in the region. Spatial structures of the SST trends are roughly consistent with the circulation pattern especially in winter when the meridional SST gradients are larger, suggesting that a horizontal advection may play an important role in the long-term SST variability in winter.  相似文献   

3.
The change of sea surface temperature(SST) in the southern Indian Ocean(SIO) during the recent six decades has been analyzed based on oceanic reanalysis and model, as well as atmospheric data. The results show that a thermal regime shift in SIO during the 1960 s, which is not caught enough attentions, has been of equal magnitude to the linear warming since 1970. Empirical Orthogonal Function(EOF) analyses reveal that a thermal shift is combined with atmospheric changes such as the weakening of westerly during the period of 1960–1967. Inner dynamic connections can be defined that when the westerly winds turn weak, the anticyclonic wind circulation between westerly winds and the trade winds decreases, which further reduces the SST to a negative peak in this period. It is noted that the shifts in the 1960 s are also evident for Southern Hemisphere. For example, subtropical high and the entire westerly winds belt at high latitudes both change dramatically in the 1960 s. This large-scaled process maybe link to the change of southern annular mode(SAM).  相似文献   

4.
This study deals with a unusual cooling event after Typhoon Mujigea passed over the northern South China Sea(SCS) in October 2015. We analyze the satellite sea surface temperature(SST) time series from October 3 to 18,2015 and find that the cooling process in the coastal ocean had two different stages. The first stage occurred immediately after typhoon passage on October 3, and reached a maximum SST drop of –2℃ on October 7 as the usual cold wake after typhoon. The second stage or the unusual extended cooling event occurred after 7d of the typhoon passage, and lasted for 5d from October 10 to 15. The maximum SST cooling was –4℃ and occurred after 12d of typhoon passage. The mechanism analysis results indicate that after landing and moving northwestward to the Yunnan-Guizhou Plateau(YGP), Typhoon Mujigea(2015) met the westerly wind front on October 5. The lowpressure and positive-vorticity disturbances to the front triggered meridional air flow and low-pressure trough,thus induced a katabatic cold jet downward from the Qinghai-Tibet Plateau(QTP) passing through the YGP to the northwestern SCS. The second cooling reached the maximum SST drop 4d later after the maximum air temperature drop of –9℃ on October 11. The simultaneous air temperature and SST observations at three coastal stations reveal that it is this katabatic cold jet intrusion to lead the unusual SST cooling event.  相似文献   

5.
The El Ni?o Southern Oscillation(ENSO) is a natural phenomenon that relates to the fluctuation of temperatures over the Pacific Ocean. The ENSO significantly affects the ocean dynamics including upwelling event and coastal front. A recent study discovered the seasonal upwelling in the east coast of Peninsular Malaysia(ECPM), which is significant to the fishery industry in this region. Thus, it is vital to have a better understanding of the influence of ENSO towards the coastal upwelling and thermal front in the ECPM. The sea surface temperature(SST) data achieved from moderate resolution imaging spectroradiometer(MODIS) aboard Aqua satellite are used in this study to observe the SST changes from 2005 to 2015. However, due to cloud cover issue, a reconstruction of data set is applied to MODIS data using the data interpolating empirical orthogonal function(DINEOF) to fill in the missing gap in the dataset based on spatial and temporal available data. Besides, a wavelet transformation analysis is done to determine the temperature fluctuation throughout the time series. The DINEOF results show the coastal upwelling in the ECPM develops in July and reaches its peak in August with a clear cold water patch off the coast. There is also a significant change of SST distribution during the El Ni?o years which weaken the coastal upwelling event along the ECPM. The wavelet transformation analysis shows the highest temperature fluctuation is in 2009–2010 which indicates the strongest El Ni?o throughout the time period. It is suggested that the El Ni?o is favourable for the stratification in water column thus it is weakening the upwelling and thermal frontal zone formation in ECPM waters.  相似文献   

6.
Air temperature is a key index reflecting climate change. Air temperature extremes are very important because they strongly influence the natural environment and societal activities. The Arctic air temperature extremes north of 60°N are investigated in the winter. Daily data from 238 stations at north of 60°N from the global summary of the day for the period 1979–2015 are used to study the trends of cold days, cold nights, warm days and warm nights during the wintertime. The results show a decreasing trend of cold days and nights(rate of –0.2 to –0.3 d/a) and an increasing trend of warm days and nights(rate of +0.2 to +0.3 d/a) in the Arctic. The mean temperature increases,which contributes to the increasing(decreasing) occurrence of warm(cold) days and nights. On the other hand,the variance at most stations decreased, leading to a reduced number of cold events. A positive AO(Arctic Oscillation) index leads to an increased(decreased) number of warm(cold) days and nights over northern Europe and western Russia and an increased(decreased) number of cold(warm) days and nights over the Bering Strait and Greenland. The lower extent of Arctic autumn sea ice leads to a decreased number of cold days and nights.The occurrences of abrupt changes are detected using the Mann-Kendall method for cold nights occurring in Canada in 1998 and for warm nights occurring in northwestern Eurasia in 1988. This abrupt change mainly resulted from the mean warming induced by south winds and an increased North Atlantic sea surface temperature.  相似文献   

7.
On the basis of data of drifting bottles＇ tracks and the current measured in anchored stations, as well as temperature and salinity observed in cruise investigations and coastal stations, ADCP current data and AVHRR surface sea temperature （SST） data on the western coast of Guangdong, synthetic results of analysis showed that the coastal currents in the west of the mouth of the Zhujiang River were mainly westward in summer, which constituted the north branch of cyclonic gyre in the east of the Qiongzhou Straits. Part of its water flowed westward into the Beibu Gulf through the Qiongzhou Straits. The coastal current pattern was not identical with the traditional current system which flowed westward in the Qiongzhou Straits in winter and eastward in summer. The summertime＇s coastal current was always westward, maybe temporarily turning northeast only when the southwest wind was strong. The important characteristics of coastal current on the western coast of Guangdong, in the Qiongzhou Straits and in the north of the Beibu Gulf were analyzed and their mechanisms also were explained.  相似文献   

8.
Knowledge of sea surface temperature(SST) behaviour is vital for long-term climate scenarios. This study highlights essential outcomes about the distinguishable and unsurprising warming of the SST along the southern border of the Levantine Basin. The analysis is based on monthly SST data for the period 1948–2018. The southern Levantine Basin has undergone SST increase, during the last 71 years. In this study, a consistent warming trend has been found for the analysed SST data series, with a rate of 0.04°C/a, i.e., 0.4°C/(10 a). From 1975 to 1991 the mean annual SST was 17.1°C, and this increased to be 19.2°C, over the period 2002–2018. Results revealed two opposite trends of variability: a decreasing trend(–0.06°C/a) over the period 1975–1991, and an increasing trend(0.2°C/a) from 2002 to 2018. Over the period 1948–2018, positive mean annual SST anomalies had an average of1.8°C, and negative anomalies had an average of –1.1°C. The lowest SST total increase was found from January to April, with values about 0.03°C, while the highest warming appeared from June to September. The driving mechanisms behind the SST changes need to be more investigated, to understand the future trends and impacts of climate change in the Levantine Basin.  相似文献   

9.
OSTIA数据在中国近海业务化环流模型中的同化应用   总被引：3，自引：0，他引：3  
The prediction of sea surface temperature(SST) is an essential task for an operational ocean circulation model. A sea surface heat flux, an initial temperature field, and boundary conditions directly affect the accuracy of a SST simulation. Here two quick and convenient data assimilation methods are employed to improve the SST simulation in the domain of the Bohai Sea, the Yellow Sea and the East China Sea(BYECS). One is based on a surface net heat flux correction, named as Qcorrection(QC), which nudges the flux correction to the model equation; the other is ensemble optimal interpolation(En OI), which optimizes the model initial field. Based on such two methods, the SST data obtained from the operational SST and sea ice analysis(OSTIA) system are assimilated into an operational circulation model for the coastal seas of China. The results of the simulated SST based on four experiments, in 2011, have been analyzed. By comparing with the OSTIA SST, the domain averaged root mean square error(RMSE) of the four experiments is 1.74, 1.16, 1.30 and 0.91°C, respectively; the improvements of assimilation experiments Exps 2, 3 and 4 are about 33.3%, 25.3%, and 47.7%, respectively.Although both two methods are effective in assimilating the SST, the En OI shows more advantages than the QC,and the best result is achieved when the two methods are combined. Comparing with the observational data from coastal buoy stations, show that assimilating the high-resolution satellite SST products can effectively improve the SST prediction skill in coastal regions.  相似文献   

10.
The surface sediment samples were collected month by month at nine stations in the Daya Bay from January to December 1987, and the number of anaerobic sulfite reducing bacteria and their spores and the regularity of seasonal change were determined. The effect of environmental factors, water temperature and the resoluble oxygen concentration in the bottom of seawater on the number of them were discussed. The results show that the number of anaerobic su|fite reducing bacteria were low in sediment of the Daya Bay, indicating that the hay was less contaminated.  相似文献   

11.
Hourly sea surface temperature(SST) observations from the geostationary satellite are increasingly used in studies of the diurnal warming of the surface oceans. The aim of this study is to derive the spatial and temporal distribution of diurnal warming in the China seas and northwestern Pacific Ocean from Multi-functional Transport Satellite(MTSAT) SST. The MTSAT SST is validated against drifting buoy measurements firstly. It shows mean biases is about –0.2°C and standard deviation is about 0.6°C comparable to other satellite SST accuracy. The results show that the tropics, mid-latitudes controlled by subtropical high and marginal seas are frequently affected by large diurnal warming. The Kuroshio and its extension regions are smaller compared with the surrounding regions. A clear seasonal signal, peaking at spring and summer can be seen from the long time series of diurnal warming in the domain in average. It may due to large insolation and low wind speed in spring and summer, while the winter being the opposite. Surface wind speed modulates the amplitude of the diurnal cycle by influencing the surface heat flux and by determining the momentum flux. For the shallow marginal seas, such as the East China Sea, turbidity would be another important factor promoting diurnal warming. It suggests the need for the diurnal variation to be considered in SST measurement, air-sea flux estimation and multiple sensors SST blending.  相似文献   

12.
Variations of monsoon wind field in the sea area along the southeastern coast of China during the ENSO events and its influence on the sea level and sea surface temperature (SST) are explored mainly on the basis of the data of monthly mean wind at 850 hPa and five coastal stations during 1973-1987. The results from the analyses of the data and theoretical estimation show that the southwest wind anomalies appeared in the study area during the events, and northeast wind anomalies occurred in general before the events. With the coastline of the area being parallel basically to the direction of the wind, an Ekman transport will result in an accumulation of the water near the coast or a departure of the water from the coast. As a result , the sea level and SST there will be affected markedly. During the events, southwest wind will intensify in the summer, and northeast wind will weaken in the winter. Their total effect is that a large negative anomaly of the sea level and SST will occur. The estimations indi  相似文献   

13.
A slowdown of sea surface height(SSH) rise occurred in the Nordic(GIN) seas around 2004.In this study,SSH satellite data and constructed steric height data for the decades before and after 2004(i.e.,May 1994 to April 2014)were used for comparative analysis.The findings indicate that the rate of slowdown of SSH rises in the GIN seas(3.0 mm/a) far exceeded that of the global mean(0.6 mm/a).In particular,the mean steric height of the GIN seas increased at a rate of 4.5 mm/a and then decreased at a slower pace.This was the main factor responsible for the stagnation of the SSH rises,while the mass factor only increased slightly.The Norwegian Sea particularly experienced the most prominent slowdown in SSH rises,mainly due to decreased warming of the 0–600 m layer.The controlling factors of this decreased warming were cessation in the increase of volume of the Atlantic inflow and stagnation of warming of the inflow.However,variations in air-sea thermal flux were not a major factor.In the recent two decades,mean halosteric components of the GIN seas decreased steadily and remained at a rate of 2 mm/a or more because of increased flow and salinity of the Atlantic inflow during the first decade,and reduction in freshwater inputs from the Arctic Ocean in the second decade.  相似文献   

14.
The impact of assimilating Argo data into an initial field on the short-term forecasting accuracy of temper- ature and salinity is quantitatively estimated by using a forecasting system of the western North Pacific, on the base of the Princeton ocean model with a generalized coordinate system （POMgcs）. This system uses a sequential multigrid three-dimensional variational （3DVAR） analysis scheme to assimilate observation da- ta. Two numerical experiments were conducted with and without Argo temperature and salinity profile data besides conventional temperature and salinity profile data and sea surface height anomaly （SSHa） and sea surface temperature （SST） in the process of assimilating data into the initial fields. The forecast errors are estimated by using independent temperature and salinity profiles during the forecasting period, including the vertical distributions of the horizontally averaged root mean square errors （H-RMSEs） and the horizontal distributions of the vertically averaged mean errors （MEs） and the temporal variation of spatially averaged root mean square errors （S-RMSEs）. Comparison between the two experiments shows that the assimila- tion of Argo data significantly improves the forecast accuracy, with 24% reduction of H-RMSE maximum for the temperature, and the salinity forecasts are improved more obviously, averagely dropping of 50% for H-RMSEs in depth shallower than 300 m. Such improvement is caused by relatively uniform sampling of both temperature and salinity from the Argo drifters in time and space.  相似文献   

15.
To understand the present actuality of the marine ecosystem in the southern coastal water region of the Shandong Peninsula and the impact of the global change and the human activities to the marine ecosystem of the region,the macrobenthic community structure was researched based on data from 26 sampling stations carried out on four seasonal cruises from December 2006 to November 2007.The data was analyzed using PRIMER 6.0 and SPSS 15.0 software packages.The results showed that 236 macrobenthic species in total were collected from the research region by the field works.Most of the species belong to Polychaeta (76 species),Mollusca (75) and Crustacea (60).Of which,33 species were common species by the four cruises.The dominant species were different among the four seasons,however,the polychaete species Nephtys oligobranchia and Sternaspis scutata were always dominant in the four seasons.The abundances and biomasses of the macrobenthos from the research region were variable in the four seasons.The results of CLUSTER and MDS analysis showed that the similarities of macrobenthic structures among the stations were low,most of the similarities were at about 40% of similarity values,only that of two stations were up to 60%.In accordance with the similarity values of the macrobenthic structures,the 26 stations were clustered as six groups at arbitrary similarity level of 30%.The ABC curve indicated that the marcofauna communities in the research region had not been disturbed distinctly.The results of BIOENV and BVSTEP (Spearman) analysis implied that the concentrations of organic matter in bottom water and heavy metal copper in sediment,water depth and temperature of bottom were the most significant environmental factors to affect the macrobentic community.  相似文献   

16.
An ensemble-based assimilation method is proposed for correcting the subsurface temperature field when nudging the sea surface temperature(SST) observations into the Max Planck Institute(MPI) climate model,ECHAM5/MPI-OM. This method can project SST directly to subsurface according to model ensemble-based correlations between SST and subsurface temperature. Results from a 50 year(1960–2009) assimilation experiment show the method can improve the subsurface temperature field up to 300 m compared to the qualitycontrolled subsurface ocean temperature objective analyses(EN4), through reducing the biases of the thermal states, improving the thermocline structure, and reducing the root mean square(RMS) errors. Moreover, as most of the improvements concentrate over the upper 100 m, the ocean heat content in the upper 100 m(OHT100 m)is further adopted as a property to validate the performance of the ensemble-based correction method. The results show that RMS errors of the global OHT100 m convergent to one value after several times iteration,indicating this method can represent the relationship between SST and subsurface temperature fields well, and then improve the accuracy of the simulation in the subsurface temperature of the climate model.  相似文献   

17.
Four sources of surface heat flux (SHF) and the satellite remote sensing sea surface temperature (SST) data are combined to investigate the heat budget closure of the Huanghai Sea (HS) in winter. It is found that heat loss occurs all over the HS during winter and the area averaged heat content change decreases with a rate of -106 W/m2. Comparing with the area averaged SHF of -150 W/m-2 from the four SHF data sets, it can be concluded that the SHF plays a dominant role in the HS heat budget during winter. In contrast, the heat advection transported by the Huanghai Warm Current (Yellow Sea Warm Current, HWC) accounted for up to 29% of the HS heat content change. Close correlation, especially in February, between the storm events and the SST increase demonstrates that the HWC behaves strongly as a wind-driven compensation current.  相似文献   

18.
In the Northwest Pacific Ocean, the squid jigging fisheries from China, Japan and other countries and regions have targeted the west winter-spring cohort of neon flying squid(Ommastrephes bartramii) from August to November since the 1970 s. This squid is a short-lived ecological opportunist with a life-span of about one year,and its population is labile and recruitment variability is driven by the environment or climate change. This variability provides a challenge for ones to forecast the key habitats affected by climate change. The catch data of O. bartramii from Chinese squid jigging fishery and the satellite-derived sea surface temperature(SST) data are used in the Northwest Pacific Ocean from August to November of 1998 to 2004, the SST preferences of O.bartramii corresponding to high values of catch per fishing day(CPUE) are determined and monthly potential habitats are predicted using a histogram analysis of the SST data. The possible changes in the potential habitats of O. bartramii in the Northwest Pacific Ocean are estimated under four climate change scenarios based on the Fourth Assessment Report(AR4) of the Intergovernmental Panel on Climate Change, i.e., 0.5, 1, 2 and 4°C increases in the SST because of the climate change. The results reveal an obvious poleward shift of the potential habitats of O. bartramii in the Northwest Pacific Ocean.  相似文献   

19.
Macrobenthic infauna and associated environmental factors influencing the benthic community in the eastern coastal region of Shandong Peninsula were analyzed in four seasonal surveys from January 2007 to October 2007 (30 stations in winter, 20 stations in other three seasons), in order to understand the community structure and the factors unfluencing the benthic distribution. PRIMER 6.0 and SPSS 15.0 software packages were adopted to analyze the environmental and macrobenthic data. The results show that there were 260 macrobenthic species in total collected from the research region. The composition of species is:Polychaeta (94 species), Crustacea (75), Mollusca (56) and Echinoderm (12), among which, only 23 species were common species in the cruises of every season. The dominant species varied from season to season; however, the polychaete species Paralacydonia paradoxa Fauvel and Echinoderm species Amphioplus japonicus (Matsumoto) were always present year-round. The abundance and biomass of the macrobenthos in the research region were variable from season to season. The results of CLUSTER and MDS analysis show that the similarities of macrobenthic structures between the stations were low; most of the similarities were at about 30% of similarity value, only two stations were up to 70%. In accordance with the similarity values of the macrobenthic structures, we divided the 20 stations into five groups by arbitrary similarity level of 30%. The ABC curve indicates that the marcofauna communities in the research region had not been disturbed massively, except two stations, SB1 and SB3. Ecologically, benthos were controlled by a combination of factors such as salinity, phytoplankton, zooplankton, SiO3-Si and temperature, and no single factor could be considered as an ecological master factor.  相似文献   

20.
20世纪90年代后期南海上层海温变化趋势的转折   总被引：1，自引：1，他引：0  
In this paper, the interdecadal variability of upper-ocean temperature in the South China Sea(SCS) is investigated based on several objectively analyzed data sets and two reanalysis data sets. The trends of the SCS sea surface temperature(SST) have changed from warming to cooling since the late 1990 s. A heat budget analysis suggests that the warming of the surface mixed layer during 1984–1999 is primarily attributed to the horizontal heat advection and the decrease of upward long wave radiation, with the net surface heat flux playing a damping role due to the increase of upward latent and sensible heat fluxes. On the other hand, the cooling of the surface mixed layer during 2000–2009 is broadly controlled by net surface heat flux, with the radiation flux playing the dominant role. A possible mechanism is explored that the variation of a sea level pressure(SLP) over the North Pacific Ocean may change the prevailing winds over the SCS, which contributes to the change of the SST in the SCS through the horizontal heat advection and heat fluxes.  相似文献   

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