成功预报厄尔尼诺

2002年初,美国国家气象局气候预报中心的一批海洋学家和气候学家预测3～6个月之后在太平洋赤道地区将有一次新的厄尔尼诺。     

南极接地冰架正在融化

南极冰盖储存着地球上 90 %的冻结淡水 ,其冻结和消融的动力特征对于气候变化具有多种意义。美国国家航空和宇宙航行局喷气推进实验室的ＥｒｉｃＲｉｇｎｏｔ和哥伦比亚大学Ｌａｍｏｎｔ Ｄｏｈｅｒｔｙ地球观测站ＳｔａｎｌｅｙＪａｃｏｂｓ在 6月 1 4日《Ｓｃｉｅｎｃｅ》刊出的文章中提出 ,南极冰架沿基线融化的速度比过去想象的迅速得多 ,与海底分离的冰块儿将要漂移。缅因大学第四纪与气候研究所冰川学家ＴｅｒｅｎｃｅＨｕｇｈｅｓ说 :“这一现象具有重要意义 ,因为人们认为气候机制包括冰体、大气和大洋之间的相互作用 ,而忽略了大洋…     

El Nino and the Southern Oscillation

Using the Comprehensive Ocean-Atmosphere Data Set (COADS), wind, surface pressure and SST fields in the Equatorial Eastern Pacific and the Equatorial South Indian Ocean were analysed comprehensively.lt is pointed out that the seesaw between surface pressure in the Equatorial South Indian Ocean and the Equatorial Southeast Pacific causes the seesaw between the wind fields in the two areas, and the seesaw of wind fields results in the seesaw of SST between Indonesia and the Equatorial Eastern Pacific. El Nino is the response of ocean to the forcing of monsoon system in the Indian Ocean and the trade system in the Pacific.     

Human-induced sedimentation at El Hamra piled mooring pier, western Mediterranean coast of Egypt

El Hamra mooring pier was constructed on the northwestern Mediterranean coast of Egypt to provide shipping services for offshore oil terminals. Although the pier was built on cylindrical piles to avoid the interruption of sediment transport towards the south, unexpected sedimentation has affected navigation and the attached fire-fighting system. To provide a basis for evaluating the sedimentation problem and to provide possible mitigation strategies, a 23-month measurement program was conducted, including measurements of hydrographic surveying, nearshore waves, longshore currents, longshore littoral transport, currents seawards of the breaker zone, and offshore currents. The results confirm that carbonate sediments are transported southwards to the pier embayment from adjacent up-coast ridges by wave-induced currents. These sediments result from extensive civil engineering works (recreational development) up-coast of the El Hamra region, involving leveling of subaerial carbonate ridges and onshore sediment disposal.     

Coral Cover Change Associated to El Niño, Eastern Pacific, Costa Rica, 1992–2001

Abstract. Changes in live and dead coral cover were documented at three localities off the Costa Rican central Pacific coast first in 1992 during the aftermath of the 1991–1992 El Niño; again in the period between 1994 and 1995, and last in January 2001. Recovery of coral communities after the 1991–1992 El Niño was expressed by a significant increase (～40 %) in 1994 of live coral cover at one locality (Manuel Antonio). A subsequent decrease (～50 %) in response to the very strong 1997–1998 episode was recorded at Manuel Antonio and Ballena, mainly due to partial tissue mortality of branching (Pocillopora spp.) and massive (Porites lobata) corals. Mortality of entire colonies associated to that event was scarce and confined to branching and nodular (Psammocora stellata) corals. This species was not found at one locality (Cambutal) in the 2001 survey and it is presumed locally extinct. The recovery of this coral and others will depend on recruits from surviving colonies in deeper waters and other coral communities in the vicinity. Within sites at a given locality, contrasting results in live coral cover variability were found. This is partially due to distinct coral assemblages, coral growth, physical exposure to tidal regime, and, related to the latter, variable duration and intensity of the warming event. In general, predominant meteorological conditions at the studied area are conducive to solar radiation (UV) stress during El Niño years and are related to changes in the atmosphere‐ocean interactions in response to the warming events.     

The El Arraiche mud volcano field at the Moroccan Atlantic slope,Gulf of Cadiz

The El Arraiche field is a new mud volcano field discovered near the Moroccan shelf edge in the Gulf of Cadiz that consists of 8 mud volcanoes in water depths from 200 to 700 m. The largest mud volcano in the field (Al Idrissi mud volcano) is 255 m high and 5.4 km wide. The cluster was discovered during a survey with the RV Belgica and studied further during Leg 2 of the TTR 12 survey onboard the R/V Prof Logachev. The 2002 surveys yielded detailed multibeam bathymetry over a 700 km² study area, dense grids of high-resolution seismic data, deep-tow sub bottom profiles, sidescan sonar mosaics over the major structures. Selected video imagery lines, video guided grab samples, dredge samples, gravity cores, and box cores were collected for groundtruthing purposes. Eight mud volcanoes in water depths from 200 to 700 m cluster around two, sub-parallel anticlines and associated active extensional faults. Rock clasts and regional seismic data locate the El Arraiche field over a Late Miocene–Pliocene extensional basin. The onset of mud volcanic activity is estimated at about 2.4 Ma and probably roots in the Cretaceous–Miocene accretionary wedge. Stacked outflows are visible up to a depth of about 500 m below the sea floor. The occurrence of long-lived mud volcanoes bear witness to continued overpressure generation at depth, either by in situ oil and gas generation or by focussed flow and accumulation in the area. Geochemical analyses of pore water from cores demonstrate the presence of thermogenic hydrocarbon processes. The activity of the mud volcanoes is indicated by the thickness of hemi-pelagic sediments covering extruded mud breccia, the occurrence of seep-typical fauna, the degree of mixing between thermogenic and biogenic hydrocarbon processes, or the depth to the base of the sulphate reduction zone. Given its structural setting and the evidence of thermogenic and biogenic hydrocarbons, the area has promising hydrocarbon potential but remains untested.     

Threshold autoregression models for forecasting El Nino events

-In this paper, monthly mean SST data in a large area are used. After the spacial average of the data is carried out and the secular monthly means are substracted, a time series (Jan. 1951-Dec. 1985) of SST anomalies of the cold tongue water area in the eastern tropical Pacific Ocean is obtained. On the basis of the time series, an autoregression model, a self-exciting threshold autoregression model and an open loop autoregression model are developed respectively. The interannual variations are simulated by means of those models. The simulation results show that all the three models have made very good hindcasting for the nine El Nino events since 1951. In order to test the reliability of the open loop threshold model, extrapolated forecast was made for the period of Jan. 1986-Feb. 1987. It can be seen from the forecasting that the model could forecast well the beginning and strengthening stages of the recent El Nino event (1986-1987). Correlation coefficients of the estimations to observations are resp     

The status of artisanal fishing in El Salvador

El Salvador is one of the most environmentally degraded nations in Latin America, but the declining fishing industry is under-studied compared with deforestation and landuse. This paper examines the reactions to fish stock decline of two generations of fishers in La Union, El Salvador on the Golfo de Fonseca, one of the most important fishing areas in Latin America, using face to face interviews and questionaires. Both older (>35 years) and younger (<36 years) fishers supplemented their income with trading, farming and loans from their relatives in the United States. All older fishers reported larger fish catches five and ten years previously than at present. Previously, fishers caught more fish, but significantly more younger fishers than older fishers reported their fathers caught more fish than they did, indicating an increasing gap in fish catches in recent decades. More younger fishers than older fishers had fathers or male kin who were also fishers, indicating young men were less likely to join fishing without a parent or kin already involved. Minorities of both older and younger fishers engaged in supplementary activities. Environmental degradation disuaded fishers from switching to farming or hunting. The findings are similar to findings elsewhere on the decline of fish resources and generational gaps in environmental knowledge, but differ in that some other studies report fewer opportunities for fishers to access alternative or complementary activities. These findings are relevant to Latin American studies, considering the great value of the Golfo de Fonseca to the livelihoods of Central America.     

Detection of the bottom facies characteristics at El Zeit Bay,Red Sea,by using a single-beam acoustic sound

El Zeit Bay is a semi-closed area with a rectangular shape which south side is connected witu northwestern side of Red Sea. The study was done to detect the characteristics of the bottom facies at El Zeit Bay. Single-beam seabed echoes combined with diving survey and sediments analyses were used to detect sea bed characteristics. The seabed floor of the study area is characterized by three physiographical distinct bottom facies; sand facies: floral facies and coral patches facies. Sand facies lies at very shallow water it extended from shore line to depth about 2 m. It has very fine sand size intercalated by mud sediments. It is characterized by very poor benthos. Floral bottom facies has medium sand which characterized by rich floral vegetation this flora appear in scattered and irregular forms. It is observed at an average depth from 4 m to 6 m. Coral patches facies is characterized by the presence of coarse sediments. The coral reef covers about 40% of the study area (29.5% hard corals and 10.5% is soft ones) while the rest of the area (60%) is characterized by different benthos. In communities general, his area characterized by high biodiversity.     

厄尔尼诺和拉尼娜现象及其预报

厄尔尼诺 (太平洋中部和东部的海水及其上空的大气圈 ,周期性重复的显著升温 )和拉尼娜 (大致在同一海区 ,同样大规模的海水降温 )现象对几乎整个地球的天气 ,甚至对气候条件所起的明显作用这一事实是不容置疑的。但是预报这两个过程的强度、开始和终止的时间却仍然是一种美好的愿望。可以认为 ,在阿斯彭德依科技局大气研究部SmithI领导下的澳大利亚学者的工作 ,向前跨了一步。他们使用了十几年来对赤道和热带太平洋地区表层水参数的自然观察资料。在澳大利亚主要地区上空 ,拉尼娜现象通常都伴随着与年平均值相比非常丰富的降水 ;厄尔尼诺…     

季风低频振荡与厄尔尼诺的发生发展

基于NCEP／NCAR逐日再分析资料，应用小波分析方法研究讨论了西太平洋、南海、阿拉伯海等近赤道季风区850hPa纬向风场低频振荡与ElNino发生发展的相关特征。研究发现，在El Nino发生前期，30－50d低频振荡会出现显著的增强，El Nino发生后，30－50d低频振荡明显减小，120－150d准定常波动加强。分析表明，近赤道季风区显著低频振荡是El Nino发生发展的一个重要前兆，低频振荡能量向甚低频段的转移和输送可能是El Nino发生的重要机理。     

简易海洋同化数据中的厄尔尼诺现象

为研究在厄尔尼诺现象演变过程中海气相互作用的性态特征,该文再次应用拓展伴随模态分析于简易海洋同化数据(SODA data).结果表明:通过相互作用形成厄尔尼诺/拉尼娜现象的海洋与大气具有明显不同的性态,气候系统中并不存在一个相对独立的热带太平洋大气变异,但是的确存在一个相对独立的热带太平洋海洋变异;原因在于大气是底部界面受热而海洋是顶部界面受热,从而导致前者具有较后者强烈得多的斜压不稳定性和能够覆盖大部分热带太平洋的赤道辐合带; 再次证实了正是直接来自中纬度海域的西风爆发和海面风辐聚导致赤道太平洋上层海水的东向移动和经向辐聚造就了厄尔尼诺所特有的增温信号.     

西风爆发、次表层暖水东移与厄尔尼诺现象

利用最近20 a的大气海洋资料,分析了厄尔尼诺事件与赤道太平洋西风异常以及赤道太平洋次表层海温之间的关系.结果表明,赤道西太平洋(5°S～5°N,120°～160°E)和赤道中东太平洋(5°S～5°N,160°E～160°W)西风异常都存在着与厄尔尼诺周期一致的年际变化,但前者还包含有显著的2～3个月季节内振荡.赤道西太平洋次表层冷暖水东移也呈现年和年际时间尺度的振荡周期.在厄尔尼诺发生前,赤道西太平洋次表层海水出现持续性增暖,赤道西太平洋西风异常频率加快,强度增强.随后赤道中太平洋(160°E～160°W)出现持续性(3个月以上)强西风异常(即西风爆发),并进一步向东扩展,同时次表层暖水沿着赤道波导东移到赤道东太平洋混合层,导致赤道东太平洋海表大面积异常增暖,形成一次厄尔尼诺现象.最后,模式模拟了1980～1984年赤道太平洋海温的变化,进一步证实了赤道纬向西风异常对暖水东移起着重要的作用.     

El Nino and anti-El Nino events in 1854-1987

-Using the COADS data set of sea surface temperature in the Equatorial Eastern Pacific, thirty one El Nino events and twenty four anti -El Nino events were identified for the period from 1854 to 1987. The results were compared with those of the other authors. The El Nino events (or anti -El Nino events ) are classified into two groups according to the timing of occrrence of the events: one starts at the first half of a year, another begins at the second half of a year. Both 1982-1983 and 1986-1987 events fall into the second group, which are characterized by the eastward migration of the positive anomaly of the sea surface temperature and the significant increasing of the anomaly in September or October.     

厄尔尼诺与影响福建的热带气旋

资料统计分析显示,ＥｌＮｉｎｏ年,影响福建的热带气旋较常年显著偏少,ＬａＮｉｎａ年,影响福建热带的气旋较常年偏多,ｔ检验表明,两者之间差异显著。其机制是,ＥｌＮｉｎｏ活动期间,西太平洋副热带高压强度大,位置偏南、偏西、ＩＴＣＺ位置偏南,热带气旋生成区对流活动弱,不利于热带气旋的生成和北上影响福建,ＬａＮｉｎｅ年,副热带高中度北,位置偏北,偏东,ＩＴＣＺ位置偏北,热带气旋生成区对流活动旺盛,有利于热     

The strong winter monsoon in East Asia and El Nino

- The relationship between meridional wind in mid - latitudes of East Asia and SST in the Equatorial Eastern Pacific is analysed in this paper. It is pointed out that there exist close relations between the seasonal changes of the meridional wind in mid - latitudes of East Asia and SST in the Equatorial Eastern Pacific. The intensification of north winds over East Asia also plays an important role in the rise of SST in Equatorial Eastern Pacific one year later. The strong winter monsoon usually occurs in previous winter of El Nino and it causes low temperature to a great extent in China . The low temperature in China can be regarded as a precursor of El Nino.     

An analysis on El Nino processes during 1949-1987

-In this paper, the outset, evolution and intensity of El Nino were analyzed. Different features were found in each El Nino process. The El Nino of 1986 was also analyzed and outlined.     

Comparison of volcanic rifts on La Palma and El Hierro, Canary Islands and the Island of Hawaii

The meso-scale (km) morphology of the well-studied volcanic rift zones on the Island of Hawaii is compared to the morphology of the lesser known rift zones of La Palma and El Hierro, Canary Islands. We find that there are both differences and similarities in their morphologic characteristics. In general, the rift zones on La Palma and El Hierro are shorter (a few tens of km in length) than those on Hawaii (ranging up to >100 km in length), perhaps reflecting both magma supply and composition. Many of the rift zones on Hawaii have well defined axial zones, both on-and offshore. In contrast, the rift zones on La Palma and El Hierro display various geometries ranging from linear ridges having smooth to irregular crests to structures with a broad fan-like morphology in plan view. The pronounced fanning may be a reflection of: 1) the stress field within the rift being insufficient to trap dikes within a narrow region, 2) dike injection and volcanism shifting laterally through time, 3) volcanoes building nearly one atop of another in the Canary Islands, superimposing the stress field of one structure on the other and thus yielding a more complex distribution of gravitational stresses, and 4) low rate of magma supply producing low magma pressures and thus randomly oriented dike injections. Irregularities and curvature along the axes of the rifts on La Palma and El Hierro may be a reflection of differences in the rate of magma production. Unlike the volcanoes on the Island of Hawaii there may be insufficient volumes of lavas erupted on La Palma and El Hierro to smooth out irregularities. The superposition of rifts from different volcanoes may also add to topographic irregularities in the Canary Islands, especially if eruption rates are low.     

Heavy Minerals and Rare Earth Elements in Coastal and Inland Dune Sands of El Vizcaino Desert,Baja California Peninsula,Mexico

A heavy mineral (HM) study and light and heavy rare earth elements (LREE and HREE) analysis were performed in coastal and inland dune sands, El Vizcaino Desert, Central Baja California Peninsula, Mexico. Our study shows high abundances of hornblende and apatite in the El Vizcaino dune sands, suggesting a dominance of granodiorites/intermediate plutonic rocks and marine authigenic phosphorite in the dune sands. There is a relationship between unstable heavy minerals like hornblende, pyroxenes, and sphene, and heavy rare earth elements (HREE) that suggests that unstable heavy minerals are potential carriers of HREE in the dune fields. However, there is a slight depletion of HREE in relation to LREE, especially in one locality of the inland dunes probably associated with the wind regime and weathering of unstable heavy minerals in the sands. Inland, transitional, and coastal dune fields can be observed as different dune provinces by means of grouping HM and REE data in two separate dendograms. It seems that HREE are correlated with fine-grained sand sizes and correlated with high CIA values linked to slightly weathered sands.     

Diagnosis of trace metal contamination in sediments: the example of Ensenada and El Sauzal, two harbors in Baja California, Mexico

Total metal concentrations in sediments from within Ensenada and El Sauzal Harbors are generally higher than at the mouths. Grain-size analyses suggested that this enrichment could be due to the presence of fine-grained sediments in the inner part of the harbors rather than to anthropogenic perturbations. The (Me/Al)(sample) ratios for Pb, Co, Ni and Fe were significantly higher for Ensenada Harbor relative to El Sauzal Harbor, whereas the ratios for Cd, Mn, Zn and Cu were statistically equivalent for both harbors. Calculated enrichment factors [EF(Me)=(Me/Al)(sample)/(Me/Al)(shale)] indicated that the metals showing slight enrichment were those associated with anthropogenic contamination (Pb, Zn), or probably related to primary productivity in the water column (Cd, Co). The levels of most of the metals were not greatly enriched, a consideration that is of the utmost importance when contamination issues are at stake.