Variations of the Eco-Hydro-Climatic Environment Response to the 2015/2016 Super El Niño Event in the Mindanao Dome Upwelling System

A super El Ni?o event occurred in the equatorial Pacific during 2015-2016,accompanied by considerable regional eco-hydro-climatic variations within the Mindanao Dome(MD)upwelling system in the tropical western Pacific.Using timeseries of various oceanic data from 2013 to 2017,the variability of eco-hydro-climatic conditions response to the 2015/2016 super El Ni?o in the upper 300 m of the MD region are analyzed in this paper.Results showed that during the 2015/2016 super El Ni?o event,the upwelling in the MD region was greatly enhanced compared to those before and after this El Ni?o event.Upwelling Rossby waves and the massive loss of surface water in the western Pacific were suggested to be the main reasons for this enhanced upwelling.De-creased precipitation caused by changes in large-scale air-sea interaction led to the increased surface salinities.Changes in the struc-tures of the thermohaline and nutrient distribution in deep waters contributed to the increased surface chlorophyll a,suggesting a po-sitive effect of El Ni?o on surface carbon storage in the MD region.Based on the above analysis,the synopsis mechanism illustrating the eco-hydro-climatic changing processes over the MD upwelling system responding to the El Ni?o event was proposed.It high-lights the prospect for the role played by El Ni?o in local eco-hydro-climatic effects,which has further profound implications for understanding the influence of the global climate changes on the ocean carbon cycle.     

黄河断流与El Ni(～n)o事件的遥相关

黄河断流事件的发生是人为因素与自然因素——人类生产活动用水量急增与天然径流量骤减共同作用的结果。自然因素作为天然背景具有不可低估的作用,在引起黄河断流的所有气候因子中,降水减少的贡献最显著,其次是蒸发增加的影响。当代黄河断流事件的发生和持续加重似与El Nin〖DD(Y-1.5mm〗~〖DD)〗o事件的频繁发生及其持续强劲有某种关联,本文即通过对黄河径流及其流域内的降水、蒸发、气温等方面气候因素与El Nin〖DD(Y-1.5mm〗~〖DD)〗o事件的遥相关作用进行分析,寻求导致黄河径流减少的可能原因,从而揭示黄河断流与El Nin〖DD(Y-1.5mm〗~〖DD)〗o事件的联系。结果表明,通常情况下,El Nin〖DD(Y-1.5mm〗~〖DD)〗o事件发生时,黄河流域年平均降水量减少10.35%,可造成黄河年径流减少12.95% (含有来自蒸发增加所造成的影响),约相当于减少73.45×108 m3的水量。随El Nin〖DD(Y-1.5mm〗~〖DD)〗o事件强度的加深,降水量与径流量均迅速递减,强El Nin〖DD(Y-1.5mm〗~〖DD)〗o事件黄河流域年平均降水量减少20.43%,黄河径流量减少25.59%（147.17×108m3）;1997年断流最严重时降水减少30.62%,径流骤减40.27%（229.96×108 m3 ）。可见El Nin〖DD(Y-1.5mm〗~〖DD)〗o事件对黄河断流所造成的影响是相当深刻的。     

1991～1995年El Ni?o事件的特征及其对中国天气气候异常的影响

利用多种资料分析了１９９１～１９９５年异常ＥｌＮｉｎｏ事件的特征及东亚环流变异和中国异常天气气候的特征。根据所采用的划分ＥｌＮｉｎｏ事件的标准和指数,９０年代初的５年里共发生了３次ＥｌＮｉｎｏ事件,即１９９１年６月～１９９２年９月、１９９３年４～１２月、１９９４年６月～１９９５年２月（简称１９９１～１９９５年３次ＥｌＮｉｎｏ事件）。这３次事件都是中部型,间隔时间短（以年尺度为主）是它们的一个显著特点。研究表明１９９１～１９９５年３次ＥｌＮｉｎｏ事件对中国天气气候的影响有许多不同的方面。其中１９９１年（ＥｌＮｉｎｏ当年）夏季和１９９２年（ＥｌＮｉｎｏ次年）夏季降水异常分布与１９５１～１９９０年间１０次ＥｌＮｉｎｏ事件的平均结果相似,但１９９３、１９９４年夏季降水与平均结果相反。这说明ＥＮＳＯ事件不是唯一决定中国夏季天气气候的强信号,还有别的气候因子影响中国夏季的天气气候异常。在东亚,夏季风的活动可能是另一个关键气候信号。通过对１９９１年和１９９４年夏季东亚大尺度环流变化和南海地区经纬向风时间演变的分析发现,两者虽都处于ＥｌＮｉｎｏ爆发的当年,但相反的环流形势造成了这两年夏季相反的降水形势。这一方面表明ＥｌＮｉ     

1961 - 2018年河西走廊寒潮频次时空变化特征及其环流影响因素研究

寒潮是我国北方地区冬、 春、 秋季节常见气象灾害之一, 产生的危害严重影响社会经济发展和人们生产生活。河西走廊生态环境脆弱且处于寒潮影响的重要区域, 揭示河西走廊寒潮频次时空变化特征可以为农牧业防灾减灾提供参考。基于1961 - 2018年河西走廊12个气象站逐日最低气温数据, 采用数据统计和空间可视化表达方法, 分析近60 a河西走廊寒潮频次时空变化特征, 并探讨北极涛动（AO）异常与寒潮频次的响应关系。结果表明： 从时间上看, 河西走廊的寒潮主要发生在10月至4月, 其中11月、 12月、 4月为寒潮高发时期, 近60 a河西走廊寒潮频次呈现出下降的趋势, 其中在20世纪80年代出现明显的低值, 下降趋势在季节上表现为秋季>春季>冬季; 河西走廊寒潮发生频次具有显著的空间差异, 其中西部地区最多, 东部地区居中, 中部地区最少; 北极涛动（AO）强弱与河西走廊寒潮频次变化具有时空响应关系, 当AO处于负相位时, 河西走廊各气象站寒潮发生频次较多, 并且在河西走廊东部和西部表现的较为明显。     

厄尔尼诺事件对太湖流域降水的影响

为了揭示1951~2016年厄尔尼诺事件影响下太湖流域夏季(6~8月)降水特征,分析了厄尔尼诺事件开始年与结束年的降水状况。结果表明:太湖流域降雨与厄尔尼诺事件存在一定的关系:(1)弱强度厄尔尼诺事件起始年的6月与6~8月、结束年的6月与7月降水均以正常、大旱与极旱为主;中等强度厄尔尼诺事件起始年的6月与6~8月以正常与大涝为主,结束年同时段以正常、偏旱与大旱为主;(超)强厄尔尼诺事件起始年6月以正常或大旱为主,8月以正常或大涝为主,结束年刚好相反。(2)(超)强厄尔尼诺起始年的夏季,西太平洋副热带高压面积偏小,位置偏东,而结束年的夏季,西伸脊点加强西伸,利于太湖流域降雨偏多。(3)(超)强厄尔尼诺起始年的全年编号台风以偏少为主,登陆台风正常略偏少,但事件的起始年夏季6~8月编号台风却以偏多为主,结束年秋季9~11月登陆台风以偏多为主;结束年6月降雨偏多,登陆台风向秋季集中,易造成流域持续洪涝,对防洪产生不利影响。     

冬季西、北江径流量异常的前期海-气背景场特征

1990年以来珠江口出现7次强咸潮,主要原因是珠江流域秋、冬季少雨,西、北江径流减少。根据实测资料,分析西、北江流域近50年来冬季径流量变化特点,从大尺度海-气相互作用出发,分析冬季径流量减少的前期海-气特征,得出E l N ino与La N ina发生次年冬季,西、北江径流量出现负距平的机率分别为10/14和10/11,与副高强弱有关。这在冬季径流量预报及珠江口咸潮超前预警上有重要参考价值。并据此预测2005/2006冬季径流量为负距平,极可能再次出现强咸潮。     

影响海南岛的热带气旋与MJO的关系

利用澳大利亚气象局MJO(Madden-Julian Oscillation)指数(1979—2015年)资料、NCEP/NCAR全球再分析格点资料和中国气象局上海台风研究所台风资料,分析了MJO不同位相、强度与7—10月影响海南岛的热带气旋活动的关系。结果表明:7—10月影响海南岛的热带气旋活跃期和沉寂期与MJO的位相和强度有关,但7—8月和9—10月的热带气旋活跃期和沉寂期对应的MJO位相和强度有所不同。在7、8月,当MJO处于强的第3、6位相或弱的第4位相时有利于热带气旋影响海南岛,当MJO处于强的第1、2、8位相时则不利于热带气旋影响海南岛。在9、10月,当MJO处于7位相时有利于热带气旋影响海南岛,当MJO处于1位相时则不利于热带气旋影响海南岛。无论是7、8月还是9、10月,有利于热带气旋偏多和偏少的MJO位相对应的环流形势基本相反。     

1954-2005年长江以北地区初霜期变化趋势

采用长江以北地区65个测站1954-2005年秋冬季逐日地面最低温度资料,计算分析长江以北地区初霜出现日期的年代际时空变化特征。结果表明：中国北方地区初霜是由北向南逐渐出现的,初霜发生日期具有明显的年代际变化特征,在20世纪90年代之后,大部分地区初霜日期偏晚的年份逐渐增多。中国北方地区初霜发生日期的早晚与北极涛动的强弱密切相关：当北极涛动处于正位相时,北半球以纬向型环流为主,中国北方大部分地区的初霜期偏晚;反之,当北极涛动处于负位相时,北半球以经向型环流为主,中国北方大部分地区的初霜期偏早。     

The magmatic feeding system of El Reventador volcano (Sub-Andean zone,Ecuador) constrained by texture,mineralogy and thermobarometry of the 2002 erupted products

After a 26 years long quiescence El Reventador, an active volcano of the rear-arc zone of Ecuador, entered a new eruptive cycle which lasted from 3 November to mid December 2002. The initial sub-Plinian activity (VEI 4 with andesite pyroclastic falls and flows) shifted on 6 and 21 November to an effusive stage characterized by the emission of two lava flows (andesite to low-silica andesite Lava-1 and basaltic andesite Lava-2) containing abundant gabbro cumulates. The erupted products are medium to high-K calc-alkaline and were investigated with respect to major element oxides, mineral chemistry, texture and thermobarometry. Inferred pre-eruptive magmatic processes are dominated by the intrusion of a high-T mafic magma (possibly up to 1165 ± 15 °C) into an andesite reservoir, acting as magma mixing and trigger for the eruption. Before this refilling, the andesite magma chamber was characterized by water content of 5.3 ± 1.0%, high oxygen fugacity (> NNO + 2) and temperatures, in the upper and lower part of the reservoir, of 850 and 952 ± 65 °C respectively. Accurate amphibole-based barometry constrains the magma chamber depth between 8.2 and 11.3 km (± 2.2 km). The 6 October 2002 seismic swarm (hypocenters from 10 to 11 km) preceding El Reventador eruption, supports the intrusion of magmas at these depths. The widespread occurrence of disequilibrium features in most of the andesites (e.g. complex mineral zoning and phase overgrowths) indicates that convective self-mixing have been operating together with fractional crystallization (inferred from the cognate gabbro cumulates) before the injection of the basic magma which then gave rise to basaltic andesite and low-silica andesite hybrid layers. Magma mixing in the shallow chamber is inferred from the anomalous SiO₂–Al₂O₃ whole-rock pattern and strong olivine disequilibria. Both lavas show three types of amphibole breakdown rims mainly due to heating (mixing processes) and/or relatively slow syn-eruptive ascent rate (decompression) of the magmas. The lack of any disequilibrium textures in the pumices of the 3 November fall deposit suggest that pre-eruptive mixing did not occur in the roof zone of the chamber. A model of the subvolcanic feeding system of El Reventador, consistent with the intrusion of a low-Al₂O₃ crystal-rich basic magma into an already self-mixed andesite shallow reservoir, is here proposed. It is also inferred that before entering the shallow chamber the “basaltic” magma underwent a polybaric crystallization at deeper crustal levels.     

Repeated recharge,assimilation, and hybridization in magmas erupted from El Chichón as recorded by plagioclase and amphibole phenocrysts

Compositional and isotopic zoning patterns in plagioclase and amphibole phenocrysts from El Chichón record multiple cycles of country rock assimilation, magma injection, hybridization, and mixing. Laser ablation ICP-MS and electron microprobe analyses of plagioclase crystals from 7 eruptions spanning 3100 years reveal four types of zoning. These compositional and isotopic zones are often associated with textural changes observed in the crystals in thin section (e.g. sieved or patchy regions). Amphiboles are frequently zoned in Al and Si, and, in two magmas, may have clinopyroxene rims. Interestingly, most plagioclase show multiple and repeated zoning patterns. Moreover, all magmas contain all zoning patterns and textures, and crystals with substantially different sequences of zones occur within mm of one another. The most reasonable explanation for the origin of these textures is a frequently recharged chamber. Plagioclase zones with increasing anorthite contents (An) and decreasing ⁸⁷Sr/⁸⁶Sr ratios record injection by a hotter, possibly wetter, and more primitive magma (lower ⁸⁷Sr/⁸⁶Sr ratio). Zones with decreasing An and increasing ⁸⁷Sr/⁸⁶Sr ratios record assimilation of country rock and/or hybridization of the host and injected magmas; injection of hot magma may provide the heat for country rock assimilation. Changes in An without corresponding changes in ⁸⁷Sr/⁸⁶Sr ratio likely record slight variations in pressure or temperature during crystallization, or the far-field thermal effects of magma injection. Variations in ⁸⁷Sr/⁸⁶Sr ratio unaccompanied by Anzoning record assimilation of country rock. Amphibole zoning patterns also record periodic heating events; amphibole with clinopyroxene rims record episodes where the magma was heated beyond the amphibole stability field. Bulk compositional homogeneity and the juxtaposition of many crystals with disparate zoning patterns in single pumice require the magmatic system to be well mixed. Strontium diffusion rates indicate that the plagioclase zoning patterns cannot have persisted at magmatic pressures and temperatures for more than ~ 500 years, thus cycles of injection and assimilation occur on timescales equal to or shorter than the eruption recurrence interval. Long-term compositional and isotopic homogeneity indicate that there is a balance between recharge, assimilation, and crystallization.