南海中部海域针飞鱼类早期发育的研究     

魏淑珍  陈真然 《海洋学报》1982,4(3):357-366

针飞鱼属Oxyporhamphus Gill(1863)是飞鱼中形态最原始的种类.其地理分布集中于太平洋、印度洋和大西洋的热带海域.针飞鱼是大洋性小型上层鱼类,也是大洋鱼类区系营养相互关系中的重要环节;它们既可为人类食用,亦是大洋重要经济鱼类(如金枪鱼、旗鱼、枪鱼、鲯鳅等)的天然食饵,故能利用飞鱼类“集群”的习性和明显起飞的特征刘断大洋经济负类的踪迹.因此,对飞鱼类的研究,具有特别重要的意义.  相似文献   

格陵兰岛冰盖消融时空特征(2003~2015年)及其对海平面上升的贡献          下载免费PDF全文

彭桢燃  胡正旺  王林松  陈超  付争妍 《地球科学》2021,46(2):743-758

研究格陵兰冰盖（GrIS）质量变化异常速率可以帮助了解异常气候事件驱动海平面变化的机制.聚焦于2010~2012年GrIS质量变化的异常速率,及其对海平面指纹（SLF）和相对海平面（RSL）变化的贡献.通过联合2003~2015年GRACE月重力场数据和表面质量平衡（SMB）数据,采用mascon拟合法及网格尺度因子恢复泄漏,获得了6个流域的质量变化时空分布.基于海平面变化方程（SLE）并考虑负荷自吸引效应估算了SLF的空间分布.结果表明,2003~2015年间GrIS总质量变化速率分别为-288±7 Gt/a及-275±1 Gt/a;而在2010~2012年间速率相应地增加至-456±30 Gt/a及-464±38 Gt/a,该时期格陵兰西北海岸及东南沿海地区呈现出大量冰盖融化,其对海平面的贡献变化呈现倒“V”型（即先升后降）,而全球平均海平面变化呈现出明显的正“V”型（即先降后升）.另外,GrIS融化对海平面的贡献约为31%,造成全球平均RSL增加了0.07 cm/a,而对斯堪的纳维亚及北欧地区的RSL贡献为-0.6 cm/a,GrIS融化造成的远海地区RSL上升速率比全球平均RSL速率高近30%.   相似文献   

Study on indirect economic impacts and their causes of the 2008 Wenchuan earthquake     

Song  Yan  Li  Zhenran  Zhang  Xiao  Zhang  Ming 《Natural Hazards》2021,108(2):1971-1995

In terms of events that undermine economic growth, the impact of natural disasters is huge and inevitable. Taking the 2008 Wenchuan earthquake as the research object, and based on the country-year data for 181 counties in Sichuan Province from 1999 to 2018, this paper uses the dynamic difference-in-difference method to investigate the indirect impact of this event on the economy. The main findings are as follows: Even though the central government has introduced reconstruction policies and invested a lot of reconstruction funds, in 2018, the per capita income in the extremely and relatively severe disaster areas was still significantly lower than the counterfactual by 21.96% and 7.61%, respectively. There is heterogeneity in the long-term indirect impacts in areas with different disaster levels, and the economies of the extremely severe disaster areas may form a "poverty trap," while the economies of the relatively severe disaster areas are still in a slow recovery state. It was further found that the assistance of central government’s reconstruction funds and the increase in local government expenditure are the reasons for the rapid economic recovery in the short term, and the insufficient level of total demand caused by the investment and consumption is the main reasons for the negative indirect impact on the economy in the disaster areas.

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