Upwelling and sedimentation dynamics     

Qu Tangdong  Hu Dunxin 《中国海洋湖沼学报》1993,11(4):289-295

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A statistical study on relationship of El Niño events to the hydrography along 137 °E in winter     

Cui Maochang  Hu Dunxin 《中国海洋湖沼学报》1991,9(2):132-145

Principal component analysis (PCA) as used by meteorologists and oceanographers is a powerful tool for analysis of the spatial and temporal variability of physical fields. This study was aimed at applying “quasi-local PCA for singular factor” to make the cumulative percentage for the first principal component as great as possible, so that a multi-dimensional problem can be reduced to a single-dimensional one, and then stepwise regression analysis can be used to parameterize the relationship between El Niño events and the hydrographic factor anomalies along 137 °E in winter. The results show that the salinity anomalies on 30 m level, the sigmat on 250 m level, and the temperature on 300 m level at 8 °N are most closely related with El Niño events because of thermocline movement caused by enhanced upwelling in this area during El Niño years.  相似文献   

Review on observational studies of western tropical Pacific Ocean circulation and climate     

Hu  Dunxin  Wang  Fan  Sprintall  Janet  Wu  Lixin  Riser  Stephen  Cravatte  Sophie  Gordon  Arnold  Zhang  Linlin  Chen  Dake  Zhou  Hui  Ando  Kentaro  Wang  Jianing  Lee  Jae-Hak  Hu  Shijian  Wang  Jing  Zhang  Dongxiao  Feng  Junqiao  Liu  Lingling  Villanoy  Cesar  Kaluwin  Chalapan  Qu  Tangdong  Ma  Yixin 《中国海洋湖沼学报》2020,38(4):906-929

The Western Tropical Pacific(WTP) Ocean holds the largest area of warm water(28℃) in the world ocean referred to as the Western Pacific Warm Pool(WPWP),which modulates the regional and global climate through strong atmospheric convection and its variability.The WTP is unique in terms of its complex 3-D ocean circulation system and intensive multiscale variability,making it crucial in the water and energy cycle of the global ocean.Great advances have been made in understanding the complexity of the WTP ocean circulation and associated climate impact by the international scientific community since the 1960 s through field experiments.In this study,we review the evolving insight to the 3-D structure and multi-scale variability of the ocean circulation in the WTP and their climatic impacts based on in-situ ocean observations in the past decades,with emphasis on the achievements since 2000.The challenges and open que stions remaining are reviewed as well as future plan for international study of the WTP ocean circulation and climate.  相似文献   

Seasonal variability of the Mindanao Current determined using mooring observations from 2010 to 2014     

Fujun Wang  Qingye Wang  Dunxin Hu  Fangguo Zhai  Shijian Hu 《Journal of Oceanography》2016,72(5):787-799

A mooring was deployed east of Mindanao Island at 8°N, 127°3′E from December 2010 to August 2014 to collect direct measurements of the Mindanao Current (MC). The Acoustic Doppler Current Profiler (ADCP) fixed on the main float shows that the MC is a strong and stable southward flow with a standard deviation less than 21 cm/s in the upper 500 m. The core flows between depths of 50 and 100 m with a maximum mean speed of 78 cm/s at 100 m. The seasonal variability of MC varies interannually and is depth-dependent. Although it takes a double-peak structure in the upper 200 m with two maxima in April and June and one minimum in October, the MC velocity has its maximum during boreal summer (June) and a minimum in autumn (September) when a 100-day low-pass filter is applied to remove intraseasonal signals. The semiannual signals are mainly limited between 200 and 350 m. The Asian monsoon intensifies the wind-driven sea-surface height anomaly (SSHA) east of Mindanao Island, and the resulting sharp slope induces meridional flow with large variability. Rossby waves and the boundary effect weaken the contribution of wind, stabilizing the flow of MC. The MC is determined by the zonal gradient of the SSHA rather than the SSHA itself, suggesting a possible inconsistency in seasonality between the Mindanao Eddy (ME) and MC. The semiannual ME signal plays an important role in the seasonal variability of MC.  相似文献   

137°经向断面温、盐度的年际变异     

顾玉荷  孙湘平  胡敦欣 《海洋学报》1999,21(6):9-16

系统地分析了137°E断面温、盐度的多年变化,主要结果为:(1)137°E断面100m层温度,在低纬度海域于某些年份出现异常低温,此现象可能与厄尔尼诺事件有关;指出棉兰老冷涡的存在是造成该断面于6°～8°N附近出现低温的主要原因。(2)厄尔尼诺期间,冬季137°E断面上28℃等温线所在纬度小于其多年平均值。(3)冬季137°E断面上次表层高盐水可划分为强型、次强型、中等型和弱型4种类型。  相似文献   

A steady model on upweling in a strait     

李永祥  胡敦欣 《中国海洋湖沼学报》1989,7(1):59-69

Hsueh and O Brien (1971) proposed a model on coastal upwelling induced by alongshore current. Their model is two - dimensional .steady , f - plane , linear and homogeneous with constant depth , in which wind effect was not considered . In the present paper, we proposed a steady model on upwelling in a strait with alongshore boundary current and wind applied on the surface. The following conclusions have been drawn.1 . Alongshore boundary current contributes more to upwelling than wind near the right coast.2. Alongshore boundary current influence can reach to about 70 km away from the right coast.3. Upwelling in the left half of the strait is mainly produced by wind .4. Under certain conditions, the combined action of wind and alongshore boundary current can produce upwelling in the middle of the strait.  相似文献   

UPWELLING AND SEDIMENTATION DYNAMICS II. A SIMPLE MODEL     

曲堂栋  胡敦欣 《中国海洋湖沼学报》1993,(4)

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Observation of the abyssal western boundary current in the Philippine Sea   总被引：2，自引：0，他引：2  

翟方国  王庆业  胡敦欣  郭小钢 《中国海洋湖沼学报》2014,32(5):1188-1197

Mooring observations were conducted from July 16, 2011 to March 30, 2012 east of Mindanao, Philippines(127°2.8′E, 8°0.3′N) to observe the abyssal current at about 5600 m deep and 500 m above the ocean bottom. Several features were revealed: 1) the observed abyssal current was highly variable with standard deviations of 57.3 mm/s and 34.0 mm/s, larger than the mean values of-31.9 and 16.6 mm/s for the zonal and meridional components, respectively; 2) low-frequency current longer than 6 days exhibited strong seasonal variation, flowing southeastward(mean flow direction of 119.0° clockwise from north) before about October 1, 2011 and northwestward(mean flow direction of 60.5° counter-clockwise from north) thereafter; 3) the high-frequency flow bands were dominated by tidal currents O 1, K 1, M 2, and S 2, and near-inertial currents, whose frequencies were higher than the local inertial frequency. The two diurnal tidal constituents were much stronger than the two semidiurnal ones. This study provides for the first time an observational insight into the abyssal western boundary current east of Mindanao based on long-term observations at one site. It is meaningful for further research into the deep and abyssal circulation over the whole Philippine Sea and the 3D structure of the western boundary current system in this region. More observational and high-resolution model studies are needed to examine the spatial structure and temporal variation of the abyssal current over a much larger space and longer period, their relation to the upper-layer circulation, and the underlying dynamics.  相似文献   

How does the Indian Ocean subtropical dipole trigger the tropical Indian Ocean dipole via the Mascarene high？   总被引：1，自引：0，他引：1  

FENG Junqiao  HU Dunxin  YU Lejiang 《海洋学报(英文版)》2014,33(1):64-76

The variation in the Indian Ocean is investigated using Hadley center sea surface temperature(SST)data during the period 1958–2010.All the first empirical orthogonal function(EOF)modes of the SST anomalies(SSTA)in different domains represent the basin-wide warming and are closely related to the Pacific El Ni o–Southern Oscillation(ENSO)phenomenon.Further examination suggests that the impact of ENSO on the tropical Indian Ocean is stronger than that on the southern Indian Ocean.The second EOF modes in different domains show different features.It shows a clear east-west SSTA dipole pattern in the tropical Indian Ocean(Indian Ocean dipole,IOD),and a southwest-northeast SSTA dipole in the southern Indian Ocean(Indian Ocean subtropical dipole,IOSD).It is further revealed that the IOSD is also the main structure of the second EOF mode on the whole basin-scale,in which the IOD pattern does not appear.A correlation analysis indicates that an IOSD event observed during the austral summer is highly correlated to the IOD event peaking about 9 months later.One of the possible physical mechanisms underlying this highly significant statistical relationship is proposed.The IOSD and the IOD can occur in sequence with the help of the Mascarene high.The SSTA in the southwestern Indian Ocean persists for several seasons after the mature phase of the IOSD event,likely due to the positive wind–evaporation–SST feedback mechanism.The Mascarene high will be weakened or intensified by this SSTA,which can affect the atmosphere in the tropical region by teleconnection.The pressure gradient between the Mascarene high and the monsoon trough in the tropical Indian Ocean increases(decreases).Hence,an anticyclone(cyclone)circulation appears over the Arabian Sea-India continent.The easterly or westerly anomalies appear in the equatorial Indian Ocean,inducing the onset stage of the IOD.This study shows that the SSTA associated with the IOSD can lead to the onset of IOD with the aid of atmosphere circulation and also explains why some IOD events in the tropical tend to be followed by IOSD in the southern Indian Ocean.  相似文献   

Role of Western Pacific Oceanic Variability in the Onset of the Bay of Bengal Summer Monsoon     

FENG Junqiao  HU Dunxin  YU Lejiang 《大气科学进展》2013,30(1):219-234

The influence of the tropical Indo-Pacific Ocean heat content on the onset of the Bay of Bengal summer monsoon(BOBSM) onset was investigated using atmospheric data from the NCEP and ocean subsurface temperature data from the Japan Metorology Agency(JMA).Results showed that the onset time of the BOBSM is highly related to the tropical Pacific upper ocean heat content(HC),especially in the key region of the western Pacific warm pool(WPWP),during the preceding winter and spring.When the HC anomalies in the WPWP are positive(negative),the onset of the BOBSM is usually early(late).Accompanied by the variation of the convection activity over the WPWP,mainly induced by the underlying ocean temperature anomalies,the Walker circulation becomes stronger or weaker.This enhances or weakens the westerly over the tropical Indian Ocean flowing into the BOB in the boreal spring,which is essential to BOBSM onset.The possible mechanism of influence of cyclonic/anti-cyclonic circulation over the northwestern tropical Pacific on BOBSM onset is also discussed.  相似文献