Japan suffered a M9.0 earthquake and massive tsunami on March 11, 2011, which seriously damaged the Fukushima Nuclear Power Plant and caused a nuclear crisis. The spread of nuclear radiation from the power plant through the atmosphere and ocean was predicted with a short-term climate forecasting model and an ocean circulation model under some idealized assumptions. If nuclear matter were leaked in the near-ground layer of 992 hPa, the climate model results show that the nuclear radiation would cover North America 10 days after the initial leakage, with the concentration at the forefront dramatically reduced to 10 millionths of the initial model concentration at the source. The radiation would span Europe in 15 days and cover much of the Northern Hemisphere in 30 days. If the initial leakage was assumed to occur in the layer 5000-m above the ground, the radiation would cover Europe in 10 days and cover much of the Northern Hemisphere in 15 days. Moreover, under the assumption that the nuclear matter leaked in the 10000-m layer, the radiation would affect much of China after 10 days. The ocean circulation model indicates that the nuclear material would be slowly transported northeast of Fukushima and reach 150°E in 50 days, and the nuclear debris in the ocean would be confined to a narrow band. Compared with the spread in the ocean, the area affected by leaked nuclear radiation in the atmosphere would be very large. Atmospheric monitors in North America and Europe will be helpful for estimating the effect in China of any leaked nuclear material.
QIAO FangLi WANG GuanSuo ZHAO Wei ZHAO JieChen DAI DeJun SONG YaJuan SONG ZhenYa
Numerical simulations using a version of the GFDL/NOAA Modular Ocean Model(MOM 3) are analyzed to demonstrate interdecadal pathway changes from the subtropics to the tropics in the South Pacific Ocean.After the 1976-77 climate shift,the subtropical gyre of the South Pacific underwent significant changes,characterized by a slowing down in its circulation and a southward displacement of its center by about 5-10 latitude on the western side.The associated circulation altered its flow path in the northwestern part of the subtropical gyre,changing from a direct pathway connecting the subtropics to the tropics before the shift to a more zonal one after.This effectively prevented some subtropical waters from directly entering into the western equatorial Pacific.Since waters transported onto the equator around the subtropical gyre are saline and warm,such changes in the direct pathway and the associated reduction in equatorward exchange from the subtropics to the tropics affected water mass properties downstream in the western equatorial Pacific,causing persisted freshening and cooling of subsurface water as observed after the late 1970s.Previously,changes in gyre strength and advection of temperature anomalies have been invoked as mechanisms for linking the subtropics and tropics on interdecadal time scales.Here we present an additional hypothesis in which geographic shifts in the gyre structure and location(a pathway change) could play a similar role.
全球动态植被模型(CLM3.5-DGVM)是美国国家大气研究中心(NCAR)开发的陆面模式CLM3.5(CommunityLand Model Version3.5)的陆地碳循环子模块,模型本身根据当地的温度和降水等环境条件计算得出植被分布。本研究参照陆地-碳模式比较计划(C-LAMP)的模拟方案和评价标准,对CLM3.5-DGVM中的碳循环过程进行了模拟与检验。结果表明,CLM3.5-DGVM高估了陆地生态系统的叶面积指数(LAI)和净初级生产力(NPP),且在中高纬地区尤为明显;其模拟的LAI最大值与观测值相比在全球尺度上有1～6个月不等的位相偏差。CLM3.5-DGVM很好的模拟了NPP的全球分布以及总初级生产力(GPP)和感热通量(SH)的季节变化,但在北半球中高纬度地区对NPP模拟过高;对陆地碳通量的年际变率模拟较好,但高估了其振幅。
The intraseasonal oscillation (ISO) events that occurred from November 2007 to February 2008 in the tropical Indian Ocean region were investigated by analyzing observational oceanic and atmospheric datasets.The results reveal that two ISO events were generated and developed from November 2007 to February 2008 in the tropical area of the Indian Ocean,which both originated from the southern African continent and propagated along a northeastward direction and finally penetrated into the equatorial eastern Indian Ocean.Compared with the general winter MJO event,which tended to travel along the equator from the western Indian Ocean into the western Pacific,the ISO of winter 2007 propagated not only along the equator into the eastern part of the Indian Ocean but was also transported northward into the subtropical region in the eastern Indian Ocean,which is more similar to the behavior of traditional summer ISO events.
