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1.
Observational data obtained during the TOGA-COARE IOP in the “warm pool” area of the Western Tropical Pacific were used to
analyze some characteristics of the intraseasonal variations in the mixed layer. The influence of westerly burst and rainfall
on SST, salinity and mixed layer depth are discussed. There are two pairs of counteracting processes in the “warm pool” mixed
layer: (1) The increase of mixed layer depth caused by local westerly bursts and the decrease of mixed layer depth caused
by larger scale easterly relaxation; (2) the vertical mixing by local wind and the strong stratification due to rainfall in
the mixed layer. Some possible mechanisms through the interactions between the intraseasonal time scale variations of the
oceanic mixed layer and atmospheric low frequency oscillations are revealed.
Supported by National Natural Science Foundation of China (49276250) and LASG of Beijing. 相似文献
2.
ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅＳｏｕｔｈＣｈｉｎａＳｅａ (ＳＣＳ)ｉｓａｓｅｍｉ ｅｎｃｌｏｓｅｄｏｃｅａｎｂａｓｉｎｌｏｃａｔｅｄａｔａｓｐｅｃｉａｌｇｅｏｇｒａｐｈｉｃｐｏ ｓｉｔｉｏｎ ,ｏｎｅｏｆｔｈｅｗｏｒｌｄ’ｓｐｒｏｎｏｕｎｃｅｄｍｏｎｓｏｏｎｒｅｇｉｏｎｓ,ｗｉｔｈｎｏｒｔｈｅａｓｔｗｉｎｄｓｐｒｅｖａｉｌｉｎｇｉｎｗｉｎｔｅｒａｎｄｓｏｕｔｈｗｅｓｔｗｉｎｄｓｉｎｓｕｍｍｅｒ,ａｎｄｉｓａｃｒｕｃｉａｌｒｅｇｉｏｎｏｆｉｎｔｅｎｓｉｖｅａｉｒ ｓｅａｉｎｔｅｒａｃｔｉｏｎｏｆｇｒｅａｔ… 相似文献
3.
We addressed the mesoscale structure variation of the central South China Sea (SCS) with the measurements by a long-lived
Argo float and a high-resolution ATLAS buoy during 1998–2002. T-S diagram indicates cooling and freshening events in 2000
and 2001 with lower salinity (0.5–0.8) and lower temperature (1–1.7°C). Significant decrease in the net heat flux and increase
in the precipitation suggest that the cooling and freshening is due to extra forcing by the atmosphere. Additional to large
year-to-year changes, intraseasonal variability is moderate in the research area. The axis of the maximum intraseasonal temperature
and salinity signals are mainly located on the thermocline. Typically, amplitude and period of intraseasonal temperature is
about 2°C and 40–60 days, and that of salinity is 0.3–0.5 and 35–60 days. Rapidly-changing winds, heat flux, and precipitation
are critical in controlling the intraseasonal fluctuations of the mixed layer of the area. Studies on heat and freshwater
balance in the mixed-layer further suggest that horizontal advection plays an important role in intraseasonal fluctuation
in the upper ocean. In addition, the energetic mesoscale propagation radiated from the east boundary is linked to the intraseasonal
variability in winter. 相似文献
4.
Previous research has defined the index of the Indian-Pacific thermodynamic anomaly joint mode (IPTAJM) and suggested that
the winter IPTAJM has an important impact on summer rainfall over China. However, the possible causes for the interannual
and decadal variability of the IPTAJM are still unclear. Therefore, this work investigates zonal displacements of both the
western Pacific warm pool (WPWP) and the eastern Indian Ocean warm pool (EIOWP). The relationships between the WPWP and the
EIOWP and the IPTAJM are each examined, and then the impacts of the zonal wind anomalies over the equatorial Pacific and Indian
Oceans on the IPTAJM are studied. The WPWP eastern edge anomaly displays significant interannual and decadal variability and
experienced a regime shift in about 1976 and 1998, whereas the EIOWP western edge exhibits only distinct interannual variability.
The decadal variability of the IPTAJM may be mainly caused by both the zonal migration of the WPWP and the 850 hPa zonal wind
anomaly over the central equatorial Pacific. On the other hand, the zonal migrations of both the WPWP and the EIOWP and the
zonal wind anomalies over the central equatorial Pacific and the eastern equatorial Indian Ocean may be all responsible for
the interannual variability of the IPTAJM. 相似文献
5.
Various data are used to investigate the characteristics of the surface wind field and rainfall on the East China Sea Kuroshio (ESK) in March and April, 2011. In March, the wind speed maximum shows over the ESK front (ESKF) in the 10 meter wind field, which agrees with the thermal wind effect. A wind curl center is generated on the warm flank of the ESKF. The winds are much weaker in April, so is the wind curl. A rainband exists over the ESKF in both the months. The Weather Research and Forecasting (WRF) model is used for further researches. The winds on the top of the marine atmosphere boundary layer (MABL) indicate that in March, a positive wind curl is generated in the whole MABL over the warm flank of the ESKF. The thermal wind effect forced by the strong SST gradient overlying the background wind leads to strong surface northeasterly winds on the ESKF, and a positive shearing vorticity is created over the warm flank of the ESKF to generate wind curl. In the smoothed sea surface temperature experiment, the presence of the ESKF is responsible for the strong northeast winds in the ESKF, and essential for the distribution of the rainfall centers in March, which confirms the mechanism above. The same simulation is made for April, 2011, and the responses from the MABL become weak. The low background wind speed weakens the effect of the thermal wind, thus no strong Ekman pumping is helpful for precipitation. There is no big difference in rainfall between the control run and the smooth SST run. Decomposition of the wind vector shows that local wind acceleration induced by the thermal wind effect along with the variations in wind direction is responsible for the pronounced wind curl/divergence over the ESKF. 相似文献
6.
In the present paper, correlation between the South China Sea summer monsoon （SCSSM） onset and heat content in the upper layer of the warm pool in the western Pacific Ocean is examined using the Scripps Institution of Oceanography dataset for the period of 1955-1998 and an approach to prediction the SCSSM onset is proposed. Correlation showes that there exists interdecadal variability of the SCSSM onset demarcated by 1970 with the largest correlation coefficient in the area west of the center of the warm pool rather than near its centers, implying certain effect from other factors involved besides ENSO. As the correlation is poor for the period before 1970, the heat content anomaly of the warm pool after 1970 is used to indicate early or late onset of the SCSSM beforehand. An ideal representative area （1°×1°） for the warm pool heat content was determined with its center at 3°N/138°E. The nearest TAO （TAO-Tropical Atmosphere Ocean-array） mooring to the center is at 2°N/137°E, and chosen to calculate the heat content for prediction. It is suggested that the TAO mooring at 2°N/137°E could be used to predict the SCSSM onset with the heat content in the upper layer, if the correlation between the SCSSM onset and the heat content of the warm pool runs like that of after 1970. On the other hand, if the situation does like the one before 1970, the representative station is determined at 13°S/74°E with relatively poor correlation, meaning that the warm pool in the western Pacific Ocean plays more important role in the SCSSM onset than the Indian Ocean. 相似文献
7.
The characteristics of the response of equatorial Pacific upper ocean current to westerly wind bursts(WWB)were analyzed in the frequency domain by using wind and ADCP data collected by the Shiyan3 during TOGA-COARE IOP,1992-1993.The preliminary results showed that the response consistedof an eastward surface jet at shallower than 60m depth,a westward counter current centering near100m and a shear layer between them,with the variations of all three being nonlinear and nearlysynchronous.The oceanic responses in the frequency domain were characterized by occurrences of a remotely forced mixed Rossby-gravity wave with period of 8-10 days in the surface jet andcountercurrent at shallower than 110 m depth,and two locally forced waves with periods of 24 daysand 4-5 days limited in shallower than 70m depth.These fluctuations of the responses depended much more on zonal wind than meridional wind.The results also revealed that the oceanic response toWWB resulted from momentum transport and energy propagation assoc 相似文献
8.
Effect of the inclined weak interlayers on the rainfall response of a bedded rock slope 总被引：1，自引：1，他引：0
Engineering experience shows that outward dipping bedded rock slopes, especially including weak interlayers, are prone to slide under rainfall conditions. To investigate the effect of inclined weak interlayers at various levels of depth below the surface on the variation of displacements and stresses in bedded rock slopes, four geo-mechanical model tests with artificial rainfall have been conducted. Displacements, water content as well as earth pressure in the model were monitored by means of various FBG (Fiber Bragg Grating) sensors. The results showed that the amount of displacement of a slope with a weak interlayer is 2.8 to 6.2 times larger than that of a slope without a weak interlayer during one rainfall event. Furthermore, the position of the weak interlayer in terms of depth below the surface has a significant effect on the zone of deformation in the model. In the slope with a high position weak interlayer, the recorded deformation was larger in the superficial layer of the model and smaller in the frontal portion than in the slope with a low position weak interlayer. The slope with two weak interlayers has the largest deformation at all locations of all test slopes. The slope without a weak interlayer was only saturated in its superficial layer, while the displacement decreased with depth. That was different from all slopes with a weak interlayer in which the largest displacement shifted from the superficial layer to the weak interlayer when rainfall persisted. Plastic deformation of the weak interlayer promoted the formation of cracks which caused more water to flow into the slope, thus causing larger deformation in the slope with weak interlayers. In addition, the slide thrust pressure showed a vibration phenomenon 0.5 to 1 hour ahead of an abrupt increase of the deformation, which was interpreted as a predictor for rainfall-induced failure of bedded rock slopes. 相似文献
9.
The upper mixed layer (UML) depth obtained from temperature is very close to that from density:the maximum is about 15m. This indicates that temperature is a good indicator of mixed layer during measurements. When the surface heat flux is balanced by a cross-shore heat flux, the surface mixed layer depth obtained from the WM model (Weatherly and Martin, 1978),hPRT, is roughly the same as observed. The mixed layer depth calculated from the PWP model (Price, Weller and Pinkel, 1986) is close to the depth obtained from thermistor chain temperature data. The results show that both the WM model and PWP model can provide a good estimate of stratification in the study area during the cruise. The value of log( h/u3) is about 9.5 in the study area, which shows that the study area is strongly stratified in summer. Observations on the northern Portugal shelf reveal high variability in stability, giving rise to semi-diurnal, semi-monthly and diurnal oscillations, and long term variations. The fortnightly oscillatio 相似文献
10.
LIU Wei and LIU Qinyu Physical Oceanography Laboratory & Ocean-Atmosphere Interaction Climate Laboratory Ocean University of China Qingdao P. R. China 《中国海洋大学学报(英文版)》2005,4(1):8-13
1Introduction The East Australian Current(EAC)partially sepa-rates from the coast of Australia(Godfrey et al.,1980)and subsequently flows eastward along the Tas-man Front(TF)(Warren,1970).When the east-ward flow reaches the northernmost point of New Zealand,it turns southeastward and becomes the East Auckland Current(EAUC).The flow that goesround the East Cape is named the Ease Cape Current(ECC).The ECC separates from North Island and proceeds eastward to the north of the Chatha… 相似文献
11.
The thermohaline structure at 4°S, 156°E was analyzed based on CTD data acquired during the TOGA COARE Intensive Observing
Period (IOP) from November, 1992 to February, 1993. The ocean responses during two Madden-Julian Oscillation (MJO) events
were preliminarily studied based on meteorological field observation. The main water masses at the observation point were
Tropical Surface Water, Southern Subtropical Lower Water and Southern Intermediate Water from surface downward. There was
good correlation of sea surface temperature with the wind field, and of the surface salinity with wind speed and rainfalls.
Both of the two surface variables were also modulated by upwelling caused by westerly winds at the observation point. The
isohaline layer was not always shallower than the isothemal layer in this observation and could be considered as the lower
limit of the diurnal variation of the isothernal layers in most cases. The existence of large variations of the maximum salinity
core is suggested to be related to the meridional motion in that depth.
Contribution No. 2264 from the Institute of Oceanology, Chinese Academy of Sciences.
This project was supported by NSFC (No. 49176255). 相似文献
12.
Lydia Dümenil 《中国海洋湖沼学报》2000,18(2):117-125
ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅＡｓｉａｎｓｕｍｍｅｒｍｏｎｓｏｏｎｓｙｓｔｅｍｉｎｃｌｕｄｅｓｔｈｅＩｎｄｉａｎ(ｏｒＳｏｕｔｈＡｓｉａｎ)ａｎｄＥａｓｔＡｓｉａｎｓｕｍｍｅｒｍｏｎｓｏｏｎｓ,ｂｏｔｈｏｆｗｈｉｃｈｆｏｒｍｔｈｅｍｏｓｔｄｒａｍａｔｉｃｍｏｎｓｏｏｎｓｙｓｔｅｍｓｉｎｔｈｅＮｏｒｔｈｅｒｎＨｅｍｉｓｐｈｅｒｅ.ＴｈｅｉｎｔｅｎｓｉｔｙｏｆｔｈｅｌａｔｔｅｒａｐｐｅａｒｓｔｏｂｅｒｅｌａｔｅｄｔｏｔｈｅｒａｉｎｆａｌｌｉｎｅａｓｔｅｒｎＣｈｉｎａ.Ｔｈｅｒｅｗｉｌｌｂｅａｎｅｍｐｔｙ… 相似文献
13.
为了研究云中微物理量与台风降水的关系,选取0908号台风"莫拉克"作为个例,利用中国自主研发的全球区域同化预报系统对台风引起的暴雨过程进行了数值模拟。该模式系统中包含有详细的云微物理过程。结合TRMM卫星资料、MODIS云顶温度资料、FY-2卫星云图以及常规地面观测等资料与模式结果进行对比分析。分析结果表明,此次强降水主要发生在福建大部分地区以及浙江东南部地区,模拟6小时累积降水最大值超过90m,模式对此次暴雨的雨带位置及其走向都有较好的模拟。台风中云微物理量的垂直分布基本可以分为3层,由冰晶与雪组成的冰相层,一般位于100～400hPa;由云水和雨水组成的液相层,一般位于600hPa之下,以及由霰与云水、雨水形成的混合层,主要分布在400～600hPa。霰在暖区的融化以及云水、雨水的碰并是降水的主要来源。 相似文献
14.
《中国海洋湖沼学报》2021,(2)
Typhoon is one of the frequent natural disasters in coastal regions of China.As shown in many studies,the impact of typhoons on the South China Sea(SCS) should not be overlooked.Super typhoon Rammasun(2014) was studied that formed in the northwestern Pacific,passed through the SCS,then landed in the Leizhou Peninsula.Remote sensing data and model products were used to analyze the spatiotemporal variations of the cold eddies,upwelling,sea surface temperature,mixed layer depth,rainfall,sea surface salinity,suspended sediment concentration,and surface-level anomaly.Results confirm the constant presence of upwelling and cold eddies in the southeast of Hainan(north of the Zhongsha Islands) and the southeast of Vietnam in July.In addition,we found the strengthening effect of super typhoon Rammasun on the upwelling and cold eddies in the SCS.The major reasons for the continuous decrease in sea surface temperature and the slow regaining of seawater temperature were the enhanced upwelling and vertical mixing caused by the typhoon.The increasing of the surface runoff in the Indochina Peninsula was mainly affected by the typhoon,with some contribution for the southeast of Vietnam's cold eddy and upwelling. 相似文献
15.
Sishili Bay is the most important aquiculture and tourism area for the city of Yantai, China; however, red tides occurred frequently and have caused huge economic losses in this bay in recent years. To gain a better understanding of the local ecological environments in the bay, we conducted this research between 2003 and 2008 to analyze variations in nutrients and chlorophyll (chl-a) during high frequency red tide period (May to September). The results show that the chl-a concentration increased from 2.70 in 2003 to 7.26 mg/m3 in 2008, while the concentration of total inorganic nitrogen (TIN) and silicate (SiO3-Si) increased lineally from 5.18 and 1.45 μmol/L in 2003 to 18.57 and 9.52 μmol/L in 2008, respectively, and the annual phosphate (PO4-P) varied between 0.15 and 0.46 μmol/L. Special attention was given to a red tide in August 2007 occurred when water temperature was high and nutrient concentrations increased sharply because of a heavy rainfall. Overall, the results show the P limitation in Sishili Bay, and reveal that red tides were caused by eutrophication from terrestrial inputs and local warm weather, particularly during rainy periods. Therefore, to control red tide, greater efforts should be made to reduce sewage discharges into Sishili Bay, particularly during rainfall seasons. 相似文献
16.
Based on the Had ISST1 and NCEP datasets,we investigated the influences of the central Pacific El Ni?o event(CP-EL)and eastern Pacific El Ni?o event(EP-EL)on the Sea Surface Temperature(SST)anomalies of the Tropical Indian Ocean.Considering the remote ef fect of Indian Ocean warming,we also discussed the anticyclone anomalies over the Northwest Pacific,which is very important for the South China precipitation and East Asian climate.Results show that during the El Ni?o developing year of EP-EL,cold SST anomalies appear and intensify in the east of tropical Indian Ocean.At the end of that autumn,all the cold SST anomaly events lead to the Indian Ocean Dipole(IOD)events.Basin uniform warm SST anomalies exist in the Indian Ocean in the whole summer of EL decaying year for both CP-and EP-ELs.However,considering the statistical significance,more significant warm SST anomalies only appear in the North Indian Ocean among the June and August of EP-EL decaying year.For further research,EP-EL accompany with Indian Ocean Basin Warming(EPI-EL)and CP El Ni?o accompany with Indian Ocean Basin Warming(CPI-EL)events are classified.With the remote ef fects of Indian Ocean SST anomalies,the EPI-and CPI-ELs contribute quite differently to the Northwest Pacific.For the EPI-EL developing year,large-scale warm SST anomalies arise in the North Indian Ocean in May,and persist to the autumn of the El Ni?o decaying year.However,for the CPI-EL,weak warm SST anomalies in the North Indian Ocean maintain to the El Ni?o decaying spring.Because of these different SST anomalies in the North Indian Ocean,distinct zonal SST gradient,atmospheric anticyclone and precipitation anomalies emerge over the Northwest Pacific in the El Ni?o decaying years.Specifically,the large-scale North Indian Ocean warm SST anomalies during the EPI-EL decaying years,can persist to summer and force anomalous updrafts and rainfall over the North Indian Ocean.The atmospheric heating caused by this precipitation anomaly emulates atmospheric Kelvin waves accompanied by low level easterly anomalies over the Northwest Pacific.As a result,a zonal SST gradient with a warm anomaly in the west and a cold anomaly in the east of Northwest Pacific is generated locally.Furthermore,the atmospheric anticyclone and precipitation anomalies over the Northwest Pacific are strengthened again in the decaying summer of EPI-EL.Af fected by the local WindEvaporation-SST(WES)positive feedback,the suppressed East Asian summer rainfall then persists to the late autumn during EPI-EL decaying year,which is much longer than that of CPI-EL. 相似文献
17.
《山地科学学报》2015,(3)
The impact of temporal variation of rainfall on the relationship between rainfall and catchment response is investigated in a catchment with high temporally variable rainfalls and a high percentage of permeable soils in the southwest of Iran.Twenty-nine storm events are classified into two classes, High Temporal heterogeneous(HT) and Low Temporal heterogeneous(LT) events using the variogram technique and the storm events of each class are analyzed to detect the relationship between Curve Number(CN) and rainfall depth. It is found that there is not a similar correlation between CN values and rainfall depths for both temporally variable classes, and hence, two different responses can be observed in the catchment according to rainfall temporal heterogeneities. For HT events, a complacent behavior is detected in which the CNs decline as rainfall depth increases while a different response, violent behavior, is observed for LT events in which the CNs rise and asymptotically approach a constant value with increasing storm size. This considerable difference between CN-P relationships derived from the two temporally variable classes of rainfall is attributed to the provocation of different runoff generation mechanisms, infiltration-excess and saturation-excess caused by rainfall temporal heterogeneities. Moreover, the results support the validity of variogram technique to classify storm events into two LT and HT classes. 相似文献
18.
X.H.Wang 《中国海洋大学学报(英文版)》2004,3(2):115-122
Floc breakup dynamics are studied by a sediment transport numerical model in an idealized tidal estuary that has a constant water depth and rapid flocculation of cohesive sediments. The focus is placed on the effects of boundary layer stratification induced by a bottom nepheloid layer on floc breakup and size distribution in the water column. In a neutrally stratified estuary, the floc size distribution follows a parabolic function with maximum values at the surface and bottom. The sediment-induced stratification in the bottom boundary layer increases the median floc sizes. Furthermore, sediment-voided convection caused by the settling lutocline generates significant turbulent kinetic energy dissipation and reduces floc size at the depth where the convective mixing happens. Below that depth, a weak local maxima in the floc size is predicted due to presence of the lutocline. The effect of sediment-stratified bottom boundary layer on the floc breakup can be consistently approximated by a linear regression between the maximal floc size and flux Richardson number. 相似文献
19.
X. H. Wang 《中国海洋大学学报(英文版)》2004,3(2):115-122
Floe breakup dynamics are studied by a sediment transport numerical model in an idealized tidal estuary that has a constant
water depth and rapid flocculation of cohesive sediments. The focus is placed on the effects of boundary layer stratification
induced by a bottom nepheloid layer on floe breakup and size distribution in the water column. In a neutrally stratified estuary,
the floe size distribution follows a parabolic function with maximum values at the surface and bottom. The sediment-induced
stratification in the bottom boundary layer increases the median floe sizes. Furthermore, sediment-voided convection caused
by the settling lutocline generates significant turbulent kinetic energy dissipation and reduces floe size at the depth where
the convective mixing happens. Below that depth, a weak local maxima in the floe size is predicted due to presence of the
lutocline. The effect of sediment-stratified bottom boundary layer on the floe breakup can be consistently approximated by
a linear regression between the maximal floe size and flux Richardson number. 相似文献
20.
The eastern edge of the western Pacific warm pool (WPWP) in the upper layer (shallower than 50m) exhibits significant zonal
displacements on interannual scale. Employing an intermediate ocean model, the dynamic mechanism for the interannual zonal
displacement of the WPWP eastern edge in the upper layer is investigated by diagnosing the dynamic impacts of zonal current
anomalies induced by wind, waves (Kelvin and Rossby waves), and their boundary reflections. The interannual zonal displacements
of the WPWP eastern edge in the upper layer and the zonal current anomaly in the equatorial Pacific west of 110°W for more
than 30 years can be well simulated. The modeling results show that zonal current anomalies in the central and eastern equatorial
Pacific are the dominant dynamic mechanism for the zonal displacements of the eastern edge of the upper WPWP warm water. Composite
analyses suggest that the zonal current anomalies induced by waves dominate the zonal displacement of the WPWP eastern edge,
whereas the role played by zonal wind-driven current anomalies is very small. A sensitivity test proves that the zonal current
anomalies associated with reflected waves on the western and eastern Pacific boundaries can act as a restoring force that
results in the interannual reciprocating zonal motion of the WPWP eastern edge. 相似文献