Evolution of an anticyclonic eddy southwest of Taiwan

Satellite images of sea-surface temperature, surface chlorophyll a concentration, and sea-level anomaly, together with ocean reanalysis data of Asia and Indian–Pacific Ocean (AIPOcean1.0), are utilized to study the three-dimensional characteristics and evolution of an anticyclonic warm eddy adjacent to the southwest coast of Taiwan during October and November 2006. Originated from the Kuroshio intrusion in the Luzon Strait, but unlike previously found westward moving anticyclonic eddies (AE) in the northeastern South China Sea, this AE was so close to the Taiwan coast and stayed where it was formed for over 1 month until it dissipated. Energy analysis is utilized to study the evolution process of the AE, and it shows that the barotropic instability (BTI) and baroclinic instability introduced by the Kuroshio intrusion flow appear to be the main energy sources for the AE. Periodical enhancement/relaxation of local northeasterly monsoon and its associated negative wind stress curl modify the current patterns in this region, reinforce the intraseasonal variability of the Kuroshio intrusion flow, and act together with Kuroshio to form the AE. Eddies detected from AIPOcean1.0 data also show that AEs are most likely to be generated southwest of Taiwan during the transition period of summer monsoon to winter monsoon, and generally, the BTI of Kuroshio intrusion contributes more than the direct wind stress work to the increase of the eddy kinetic energy for the generation and growth of the AEs.     

江西星子县东牯岭花岗石矿山环境地质问题及对策

长期的露天开采严重破坏了矿山地理地质环境,产生了地质灾害隐患。在介绍矿区地理地质背景的基础上,系统地描述该矿区土地、植被、地形和地貌被破坏的情况,分析崩塌、滑坡和泥石流地质灾害隐患。为改善生态环境,打造全国知名旅游景区,提出全面停止矿山开采,并进行分期治理。先期重点清除存在隐患的废石堆,然后清除边坡破碎危岩体,并辅以绿化措施。     

Decadal variation of thermocline-sea surface temperature feedback in the tropical Indian Ocean and the underlying mechanisms

The thermocline-sea surface temperature (SST) feedback is the most important component of the Bjerknes feedback, which plays an important role in the development of the air-sea coupling modes of the Indian Ocean. The thermocline-SST feedback in the Indian Ocean has experienced significant decadal variations over the last 40 a. The feedback intensified in the late twentieth century and then weakened during the hiatus in global warming at the early twenty-first century. The thermocline-SST feedback is most prominent in the southeastern and southwestern Indian Ocean. Although the decadal variations of feedback are similar in these two regions, there are still differences in the underlying mechanisms. The decadal variations of feedback in the southeastern Indian Ocean are dominated by variations in the depth of the thermocline, which are modulated by equatorial zonal wind anomalies. Whereas the decadal variation of feedback in the southwestern Indian Ocean is mainly controlled by the intensity of upwelling and thermocline depth in winter and spring, respectively. The upwelling and thermocline depth are both affected by wind stress curl anomalies over the southeastern Indian Ocean, which excite anomalous Ekman pumping and influence the southwestern Indian Ocean through westward propagating Rossby waves.     

Recent improvements to the physical model of the Bohai Sea,the Yellow Sea and the East China Sea Operational Oceano-graphy Forecasting System

In order to satisfy the increasing demand for the marine forecasting capacity, the Bohai Sea, the Yellow Sea and the East China Sea Operational Oceanography Forecasting System (BYEOFS) has been upgraded and improved to Version 2.0. Based on the Regional Ocean Modeling System (ROMS), a series of comparative experiments were conducted during the improvement process, including correcting topography, changing sea surface atmospheric forcing mode, adjusting open boundary conditions, and considering atmospheric pressure correction. (1) After the topography correction, the volume transport and meridional velocity maximum of Yellow Sea Warm Current increase obviously and the unreasonable bending of its axis around 36.1°N, 123.5°E disappears. (2) After the change of sea surface forcing mode, an effective negative feedback mechanism is formed between predicted sea surface temperature (SST) by the ocean model and sea surface radiation fluxes fields. The simulation errors of SST decreased significantly, and the annual average of root-mean-square error (RMSE) decreased by about 18％. (3) The change of the eastern lateral boundary condition of baroclinic velocity from mixed Radiation-Nudging to Clamped makes the unreasonable westward current in Tsushima Strait disappear. (4) The adding of mean sea level pressure correction option which forms the mean sea level gradient from the Bohai Sea and the Yellow Sea to the western Pacific in winter and autumn is helpful to increasing the fluctuation of SLA and outflow of the Yellow Sea when the cold high air pressure system controls the Yellow Sea area.     

不同扰动方式对沙砾质戈壁地表风蚀量的影响

通过野外风洞实验,测定了不同破坏方式、破坏面积和风速下的沙砾质戈壁风蚀量。结果表明：不同破坏方式引起的风蚀量不同,扰动强度越大造成的风蚀量越多;相同扰动方式下连续破坏造成的风蚀量稍高于间隔破坏。风蚀总量随破坏面积的增大而增加,且服从指数函数。风速为8～10 m·s^-1时,扰动的戈壁地表以轻微侵蚀为主;10～12 m·s^-1 是风蚀量增幅最大阶段;当风速大于 12 m·s^-1时,以强烈风蚀为主。风沙流中沙物质的主体是细沙和极细沙,在20 cm高度范围内,自风沙流下层至上层细沙含量比较稳定,极细沙含量逐渐降低,中沙含量逐渐上升。     

新疆小城镇经济发展的投资趋向与重点研究

在分析国内外小城镇投资情况的基础上,重点对新疆146个小城镇投资情况进行了汇总、分析及典型调查研究,分析了新疆大部分小城镇的投资效益,指出了小城镇建设存在的问题。在此基础上提出了未来5年新疆小城镇经济发展投资的总体思路：以国家和自治区财政资金为引导资金,以市场为导向,结合小城镇各自的实际,吸引民间投资、银行贷款、国外投资等各种社会资金来促进小城镇产业的发展,形成新疆干旱区绿洲环境条件下具有地方民族特色的小城镇经济发展投资模式。并首次提出农、林、水、牧业投资与小城镇建设相结合的农业资金使用方法。     

2001年1月26日高纬磁层顶通量管事件的观测研究--空间电流密度计算及分析

讨论了三种根据Cluster Ⅱ四颗卫星的磁场测量数据计算空间电流的方法及其误差,论证了这几种方法的内在一致性,并得到了完全相同的计算结果. 进而依据Cluster Ⅱ 磁场探测资料,计算了2001年1月26日多重磁通量管和FTE事件中高纬磁层顶边界层和磁鞘区的电流密度. 结果表明,磁通量管内电流密度较大,可达到约10-8A/m2;计算精度较高,结果可靠. 本文还应用最小方差分析法（MVA）,发现电流方向与通量管的轴向基本一致;论证了电流MVA分析在研究通量管性质时的作用,同时提出了电流管的概念.     

Preliminary Study on the Dynamic Variations of the Surface Thermal Flux before and after the M_S5.7 Earthquake of 2005 in Jiujiang City,Jiangxi Province

The temporal and spatial variations of surface latent heat flux （SLHF） and diagnostic air temperature at 2m before and after the Ms5.7 earthquake occurring on November 26, 2005 in the area between Ruichang City and Jiujiang City, Jiangxi Province are summarized in this paper. It is found that before the earthquake significant SLHF anomalies and air temperature anomalies occurred in the epicentral area and its vicinity. The air temperature anomalies appeared from the 2nd to the 13th of November, 2005 and were concentrated at the epicentral area and in its southern part. Then two days later, that is, from the 4th to the 15th of November 2005, significant SLHF anomalies occurred in the epicentral area and to its northern area where many lakes are distributed along the active faults. During the anomalous period, the SLHF and air temperature at 2m exceeded the sum of average daily value over 26 years and 1.5 times of its mean square deviation. Both anomalies had maintained for 12 days with a peculiar distribution related to the tectonic active zone. It is considered that both of air temperature anomalies and SLHF anomalies are correlated to the movement of thermal flux from underground prior to earthquake. SLHF anomalies occurred over wide regions covered with abundant water, whereas air temperature anomalies occurred over land.     

Has the stilling of the surface wind speed ended in China?

Since the 1960 s, the global land surface wind speed(SWS) has significantly weakened, a phenomenon known as global terrestrial stilling. The latest research found that the stilling reversed around 2010, and since then the global SWS has been strengthening. However, there is still a lack of systematic quantitative analysis in China. We analyzed the transition and regional differences in the long-term trends of the SWS in China based on observational SWS data from 1971 to 2019. The results showed that annual mean SWS in China underwent a reversal from a continuously weakening trend to a significantly strengthening trend around 2014 and implying that stilling may have ended in 2014. The reversal had obvious regional and seasonal variations. In Northeast China, Western Xinjiang as well as on the Tibetan Plateau, the years with both annual and seasonal mean SWS changing from weakening to strengthening were around 2013/2014, 1993/1994, and 2000. However, in the west of North China,SWS showed an obviously strengthening trend only in autumn and winter after 2007; while only autumn mean SWS showed a strengthening trend after 2012 in South China. It should be noted that stilling is ongoing in the eastern and southern coastal areas,North China and Eastern Xinjiang.     

北京“7·21”特大暴雨中的干侵入分析研究

利用中尺度数值模式WRF V3.2模拟分析2012年7月21日发生在北京特大暴雨过程的天气形势与中尺度系统特征,并结合干侵入理论分析了暴雨过程中的干冷空气活动及其对暴雨的影响。结果表明,此次暴雨过程发生在高空槽引导冷空气南下与强盛的西南暖湿气流在华北一带剧烈交汇的天气形势下,西太平洋副热带高压阻碍了高空槽东移,使北京地区的降水过程维持较长时间。暴雨过程伴随着明显的中尺度对流复合体MCC活动,MCC的持续活动与降水中心在时空上具有一致性。WRF模式对暴雨过程有较好的模拟能力,降水发生之前的24 h内不断有来自35°N对流层顶附近的高位涡、低湿的干冷空气,沿着倾斜向北向下的路径侵入大气中低层39°N附近的700 h Pa高度。干侵入在降水开始前24 h到降水前10 h强度变化不大,随后略有减弱,在降水开始之后迅速减弱消失。干侵入对暴雨的影响主要通过在降水开始前及降水初期影响北京地区的大气热力与动力环境来完成。干侵入可以增大暴雨落区大气的位势不稳定,为对流发展储备充沛的对流有效位能,为MCC的发生、发展提供有利的环境条件。同时,干侵入增大了大气中低层的气旋性涡度,有利于中低层空气辐合上升运动,是引发北京地区局地的强对流天气,如MCC及其伴随的暴雨过程可能的触发机制。