135°E以西西北太平洋热带气旋迅速加强的气候特征

１３５°Ｅ以西迅速加强的西北太闰洋热带气旋（２４小时中心最大风速增大２０ｍ／ｓ）以上），几乎全部经过我国邻近海域，其中７１％在我国登陆，对我国渔业生产的沿海经济建设造成较大的危害。     

华东中尺度地形对浙北暴雨影响的模拟研究

以一次梅雨降水为例，利用中尺度模式进行一系列中尺度地形对降水的增幅影响的敏感性试验。结果表明，中尺度地形对强降水区域的分布和强度有很大的影响，强降水中心位于地形附近，地形引起的１２小时降水增幅高达总降水的９０％以上；中尺度地形作为一种外界迫动，初始在低层形成气旋性辐合和水汽热量的集中，然后通过凝结潜热释放所造成的中高层增温和高层辐散，使得地形垂直环流加强和向上伸展。于是在降水、潜热释放与地形垂直环流之间出现一种正反馈机制，导致地形对降水的强烈增幅；同时午后下垫面加热所形成的不稳定层结也有利于地形垂直环流的不稳定发展，产生新的雨峰；初始场的中尺度扰动似乎在降水的地形性增幅中并不起明显作用。     

The Expansion of Intensive Beef Farming to the Brazilian Amazon

Systems of intensive animal farming, such as the confinement of beef cattle, are widespread in the developed world. Such practices have been under scrutiny since the 1960s for animal welfare and pollution issues. Here, we document the expansion of intensive beef farming to the Brazilian Amazon in order to assess socio-environmental implications. Using a combination of data mining and field surveys, we developed a georeferenced dataset of 201 cattle confinements in the states of Mato Grosso (Cerrado and Amazon biomes), Pará and Rondônia (Amazon biome), collected in 2017. In Mato Grosso, the country’s agribusiness powerhouse, confinements are well established and account for ˜20% of the cattle slaughter. But rapid expansion in Pará and Rondônia remains largely unnoticed due to the absence of data since 2012. We used the new dataset to map cattle confinements across space and time. For the first time, (1) we document an expansion to the Amazon biome; (2) we also show that confinements are associated with substantially higher productivity rates, though intensified pasture-based systems can reach comparable yields; (3) that confinements have crop production levels 2-3 times higher than comparable properties, both in- and out-of-farm; and (4) that confinements tend to slow down on-property deforestation when compared to fattening ranches in the Amazon biome, although off-property effects could be substantial and need further study. Overall, the implications of intensive beef farming for animal welfare and local waste generation in Brazil require attention as pressure to avoid deforestation continues to stimulate the practice.     

Convective Bursts Episode of the Rapidly Intensified Typhoon Mujigae(2015)

Convective burst(CB) characteristics at distinct stages of a rapidly intensified Typhoon Mujigae(2015), are investigated based on a 72-h simulation. The spatial features show that almost all CB elements develop in the eyewall. The number of CBs in the inner-core region within a 100 km radius—which account for a large proportion of the total CBs, with a sharp increase about 6 h before the onset of rapid intensification(RI)—provides some indication of the RI of the typhoon. The CBs during pre-RI and RI are examined from dynamic and thermodynamic viewpoints. The combination of lower-level convergent inflow and upper-level divergent outflow pushes a relay-race-like transmission of convective activity, favorable for the development of deep convection. A double warm-core structure is induced by the centripetal outflow sinking and warming associated with CBs, which directly accelerates RI by a sudden decrease in hydrostatic pressure. By utilizing the convection activity degree(CAD) index derived from the local total energy anomaly, a correlation formula between CBs and CAD is deduced.Furthermore, an intense CAD(ICAD) signal threshold(with a value equal to 100) to predict CBs is obtained. It is verified that this ICAD threshold is effective for estimating the occurrence of a CB episode and predicting RI of a typhoon. Therefore,this threshold may be a valuable tool for identifying CB episodes and forecasting rapidly intensified typhoons.     

初始涡旋结构对热带气旋强度变化影响的数值研究

本文利用中尺度WRF模式,通过构造3个位于不同高度上强度相同的初始涡旋暖心中心(分别称为Low试验、Mid试验和High试验),认识暖心垂直结构对热带气旋发展的影响。理想数值试验发现,在积分6 h后在Low试验和Mid试验中最大风速半径开始收缩,眼墙内对流发展,高层暖心发展明显比High试验强,强度增加明显快于High试验,达到快速增强的标准。进一步诊断发现,暖心偏低的试验中初始CAPE值较大,低层风垂直切变较强,有利于眼墙内对流发展,非绝热加热在高层暖心形成过程中起重要作用,最大风速半径收缩比High试验快,热带气旋强度快速增加。本研究清楚表明,数值预报模式中构造初始涡旋的暖心高度对模拟热带气旋的强度发展有重要影响。     

Variability of Current Structure Due to Meso-Scale Eddies on the Bottom Slope Southeast of Okinawa Island

The relationship between the vertical profile of current on the bottom slope southeast of Okinawa Island and the offshore meso-scale eddy propagated from the east was examined by combined use of the data obtained by a moored upward-looking ADCP (Acoustic Doppler Current Profiler), PIES (Inverted Echo Sounder with Pressure gauge), hydrographic surveys and satellite altimetry during a period from November 2000 to August 2001. The variability of current component parallel to the isobath in the layer over 600 m is found to be markedly different from that in the layer below 600 m. The current variability in the upper and the lower layer can be well explained by the first and second modes of the EOF (Empirical Orthogonal Function) decomposition. The PIES and the sea surface height anomaly data suggest that the first mode represents the surface-trapped current associated with the approach of the offshore meso-scale eddy from the east, whereas the second mode has a bottom-intensified structure. The second mode velocity tends to delay to the first mode. The hydrographic data derived from CTD (Conductivity-Temperature-Depth meter) and PIES data along the line across the isobath suggest that the second mode component is generated by the interaction between the meso-scale eddy and the bottom topography.     

Balance of Volume Transports between Horizontal Circulation and Meridional Overturn in the North Pacific Subarctic Region

Horizontal and meridional volume transports on timescales from intra-seasonal to interannual in the North Pacific subarctic region were investigated using a reanalysis dataset for 1993–2001 that was constructed from an assimilation of the TOPEX altimeter and in situ data into an eddy-permitting North Pacific ocean general circulation model. The barotropic flow is excited along east of the Emperor Seamounts by the western intensification dynamics. The volume transport of this flow compensates for that across the interior region east of the Seamounts below the summit depth of the Seamounts. The Oyashio, which is also considered as a compensation flow for the transport in the whole interior region, includes baroclinic as well as barotropic components. Baroclinic transports in the whole interior region exceed those in the western boundary region in the upper (200–1000 m) and lower (2000–5000 m) layers, and the total transport is northward (southward) in the upper (lower) layer. These excesses of the baroclinic transport are balanced by a vertical transport of the meridional overturn. The meridional overturn has a complementary relation to the basin-scale baroclinic circulation in the North Pacific subactic region. This revised version was published online in July 2006 with corrections to the Cover Date.     

Land use sustainability on the South-Eastern Amazon agricultural frontier: Recent progress and the challenges ahead

The recent decoupling of deforestation and soybean production has raised optimistic expectations towards enhanced land use sustainability in the South-Eastern Amazon agricultural frontier. Nonetheless, assessing land use sustainability implies not only the consideration of how agricultural activities affect natural ecosystems but also how they impact on society and how society can cope with them. We review some of the forthcoming challenges that the agricultural sector should address to confirm its significant progress towards land use sustainability. Firstly, we assess the recent efforts to adopt environmentally friendly practices with regard to the ongoing intensification process mainly based on double cropping systems. Secondly, while rapid agricultural development has brought major social advances, we evidence a recent trend towards a decoupling of soy production and the Human Development Index at municipality level. We then put this result into perspective considering that the trend towards agricultural intensification based on the use of large amounts of agrochemicals could lead to major health concerns which are still too rarely considered. Finally, we discuss how the recent efficient policies to contain deforestation in the Amazon can cause indirect land use changes in the Brazilian Cerrados and in African Savannas, thus potentially leading to an “illusion of preservation” at global scale. We conclude that new indicators involving social sciences are necessary to better address the complexity of land use sustainability on the still very dynamic agricultural frontier in the South-Eastern Amazon.     

Kinetic Energy Budgets during the Rapid Intensification of Typhoon Rammasun (2014)

In this study, Typhoon Rammasun(2014) was simulated using the Weather Research and Forecasting model to examine the kinetic energy during rapid intensification(RI). Budget analyses revealed that in the inner area of the typhoon,the conversion from symmetric divergent kinetic energy associated with the collocation of strong cyclonic circulation and inward flow led to an increase in the symmetric rotational kinetic energy in the lower troposphere. The increase in the symmetric rotational kinetic e...     

2006号台风“米克拉”近海急剧增强诊断分析

利用ERA-5再分析资料、日本葵花8号卫星黑体亮温资料以及中国气象局上海台风研究所台风最佳路径集资料,对2020年第6号台风“米克拉”（2006）近海强度急剧增强进行诊断分析。（1） 比常年偏暖的29～30 ℃的南海东部海温是“米克拉”急剧增强的有利下垫面条件;200 hPa加强东移的南亚高压、500 hPa加强西伸的副高、低层加强的偏南-西南急流是主要影响系统;相对比深层和高层大气,持续低于4 m/s的低层大气垂直风切是重要因子。（2） “米克拉”的增强主要体现在对流层低层动能的不断增强,在台风急剧增强过程中,中低层的气旋性涡度、低层辐合强度、中高层辐散强度以及上升运动均明显加强;对流层中高层动能在台风急剧增强前的减小可能与增强的高空出流相关。（3） 在“米克拉”急剧增强前,深对流云系强度不断增强,但覆盖面积变化不大;在急剧增强阶段,深对流云系组织的更加紧实集中,覆盖面积明显增大。