模式内部变率引起的1.5℃和2℃升温阈值出现时间模拟的不确定性研究

模式内部变率是模拟结果不确定性的重要来源,然而它对于1.5℃和2℃升温阈值出现时间不确定性的影响尚不清楚。因此,基于耦合模式比较计划第五阶段(CMIP5)的多模式数据研究了模式内部变率对1.5℃和2℃升温阈值出现时间不确定性的影响以及对未来排放情景的敏感性。结果表明,模式内部变率对升温阈值出现时间模拟的影响与外强迫的影响相当,单个模式内部不同成员达到全球平均1.5℃或2℃增温的年份相差2~12年;其影响具有明显的空间差异,影响极大值出现在欧亚大陆以北洋面、白令海峡周围区域、北美东北部及其与格陵兰岛之间的海域、南半球高纬地区等;低排放情景下模式内部变率的影响大于高排放情景。     

An Operational Precipitable Water Vapor Retrieval Algorithm for Fengyun-2F/VISSR Using a Modified Three-Band Physical Split-Window Method

The Visible and Infrared Spin-Scan Radiometer(VISSR) onboard the Fengyun-2(FY-2) satellite can provide valuable thermal infrared observations to help create a precipitable water vapor(PWV) product with high spatial and temporal resolutions. The current FY-2/VISSR PWV product in operation is produced by using a traditional two-band physical split-window(PSW) method, which produces low quality results under dry atmospheric conditions. Based on the sensitivity characteristics of FY-2 F/VISSR water vapor channel and two split-window channels to atmospheric water vapor, this study developed a new, robust operational PWV retrieval algorithm for FY-2 F to improve the operational precision of the current PWV product. The algorithm uses a modified three-band PSW method, which adds a scale for the water vapor channel in the improved three-band PSW method. Integrated PWV products from the radiosonde data in 2016 are used here to validate the precision of the PWV retrieved by the modified three-band and traditional two-band PSW methods. The mean bias, root mean square error(RMSE), and correlation coefficient of the PWV retrieved by the modified three-band PSW method are 0.28 mm, 4.53 mm, and 0.969, respectively. The accuracy is much better than the PWV retrieved by the two-band method, whose mean bias, RMSE, and correlation coefficient are 12.67 mm, 29.35 mm, and 0.23. Especially, in mid-or high-latitude regions, the RMSE of the PWV is improved from 10 to 2 mm by changing the inversion in the two-band method to the modified three-band PSW method. Furthermore, the modified three-band PSW results show a better consistency with the radiosonde PWV at any zonal belt and season than the two-band PSW results. This new algorithm could significantly improve the quality of the current FY-2 F/VISSR PWV product, especially at sites where the actual PWV are lower than 15 mm.     

NUMERICAL PREDICTION OF AN EXTREME RAINSTORM OVER THE PEARL RIVER DELTA REGION ON 7 MAY 2017 BASED ON WRF-ENKF

An ensemble Kalman filter based on the Weather Research and Forecasting Model (WRF-EnKF) is used to explore the effectiveness of the assimilation of surface observation data in an extreme local rainstorm over the Pearl River Delta region on 7 May 2017. Before the occurrence of rainstorm, the signals of weather forecasts in this case are too weak to be predicted by numerical weather model, but the surface temperature over the urban area are high. The results of this study show that the wind field, temperature, and water vapor are obviously adjusted by assimilating surface data of 10-m wind, 2-m temperature, and 2-m water vapor mixing ratio at 2300 BST 6 May, especially below the height of 2 km. The southerly wind over the Pearl River Delta region is enhanced, and the convergence of wind over the northern Guangzhou city is also enhanced. Additionally, temperature, water vapor mixing ratio and pseudoequivalent potential temperature are obviously increased over the urban region, providing favorable conditions for the occurrence of heavy precipitation. After assimilation, the predictions of 12-h rainfall amount, temperature, and relative humidity are significantly improved, and the rainfall intensity and distribution in this case can be successfully reproduced. Moreover, sensitivity tests suggest that the assimilation of 2-m temperature is the key to predict this extreme rainfall and just assimilating data of surface wind or water vapor is not workable, implying that urban heat island effect may be an important factor in this extreme rainstorm.     

利用FY-2F快速扫描资料分析对流初生阶段的云顶物理量特征

基于FY-2F静止气象卫星提供的2015年5—9月的高分辨率数据,通过温度阈值法识别出深、浅对流后,分析和比较了深、浅对流在对流初生(convective initiation,CI)至发展阶段中云顶高度、云顶快速降温率(cloud top cooling rate,CTC)以及多通道差值等云顶物理量特征的变化异同。结果表明:深、浅对流在CI阶段的云顶物理量特征具有相似变化特征,即云顶高度均在短时间内快速上升,CTC值均先减小后增大;深、浅对流差异表现为深(浅)对流云顶上升高度能(不能)超越水汽层高度;深对流CTC最低值较浅对流CTC最低值更低。基于CI阶段深、浅对流的CTC最低值的差异,通过个例验证,表明利用深、浅对流CTC最低值的差异,可以在识别出CI的基础,判断出CI是否发展成为深对流,从而能提前做出预警。     

基于模糊熵的GLLE熵阈值分割方法

图像分割是计算机视觉中基础且重要的一个问题.熵阈值图像分割作为一种有效的分割方法,被广泛应用于模式识别和图像处理中.传统的图像分割方法并不能获得足够有效的图像特征.为解决这个问题且进一步探究熵阈值在图像分割中的应用,引入一种GLLE（Gray Level and Local Entropy）二维直方图改进熵阈值图像分割模型,并提出了基于模糊熵的方法计算所建立的二维直方图模型.通过标准实验数据集上的对比实验表明,基于模糊熵的GLLE熵阈值分割方法可以得到更加准确的阈值,提高了分割精度.同时在处理不同类型图像的表现上优于往常的算法,具有更强的鲁棒性.     

柱撑蛭石吸附去除废水中重金属离子的实验研究

分别利用有机柱化剂十二烷基磺酸钠(SDS)和无机柱化剂聚羟基铝(HA)对蛭石进行柱撑制得十二烷基磺酸钠柱撑蛭石(SDS-V erm icu lite)和聚羟基铝柱撑蛭石(HA-V erm icu lite),并通过XRD、红外光谱、ZETA电位等表征手段对柱撑蛭石进行表征,同时针对柱撑蛭石对Cu2 ,Cd2 ,C r3 3种重金属离子的吸附进行研究,结果表明:吸附去除率受反应时间、重金属离子的初始浓度、pH值等因素的影响,经柱撑后的蛭石对重金属离子吸附的吸附性能比蛭石原矿要强。柱撑蛭石吸附3种重金属离子的动力学吸附过程可用E lov icb方程和双常数方程进行较好的拟合。     

冕宁-德昌稀土成矿带碳酸岩流体研究

通过对四川冕宁-德昌稀土矿带主要矿物中包裹体岩相学、显微测温分析与包裹体成分分析,指出由岩浆碳酸岩分异出的成矿流体为富含高密度CO2、K、Na、SO42-和多种成矿元素的超临界流体,流体以高温、高压、超高盐度、富CO2为特征,从早期到晚期流体中CO2含量增加。结合前人对碳酸岩流体、稀土矿带周边新生代盆地中无机成因CO2气藏、富钾卤水、稳定同位素和隋性气体同位素研究成果,从碳酸岩流体的性质、流体体系、碳、氦同位素组成,初步探讨了碳酸岩流体与周边新生代盆地中CO2气藏、富钾卤水的成因联系。     

Loss of energy dissipation capacity from the deadzone in linear and nonlinear viscous damping devices

In a viscous damping device under cyclic loading, after the piston reaches a peak stroke, the reserve movement that follows may sometimes experience a short period of delayed or significantly reduced device force output. A similar delay or reduced device force output may also occur at the damper’s initial stroke as it moves away from its neutral position. This phenomenon is referred to as the effect of “deadzone”. The deadzone can cause a loss of energy dissipation capacity and less efficient vibration control. It is prominent in small amplitude vibrations. Although there are many potential causes of deadzone such as environmental factors, construction, material aging, and manufacture quality, in this paper, its general effect in linear and nonlinear viscous damping devices is analyzed. Based on classical dynamics and damping theory, a simple model is developed to capture the effect of deadzone in terms of the loss of energy dissipation capacity. The model provides several methods to estimate the loss of energy dissipation within the deadzone in linear and sublinear viscous fluid dampers. An empirical equation of loss of energy dissipation capacity versus deadzone size is formulated, and the equivalent reduction of effective damping in SDOF systems has been obtained. A laboratory experimental evaluation is carried out to verify the effect of deadzone and its numerical approximation. Based on the analysis, a modification is suggested to the corresponding formulas in FEMA 356 for calculation of equivalent damping if a deadzone is to be considered.     

印尼8.7、8.5级远震对云南地区小震的激发和地下流体异常响应初探

2004年12月26日和2005年3月29日,印度尼西亚苏门答腊西北海域相继发生8.7和8.5级地震。通过对这两次地震与云南地震活动关系和地下流体记录异常变化的分析,认为:印尼两次8级地震的发生可能会使云南提前进入新一轮强震活跃期;远震对云南地区小震的激发和导致地下流体记录出现异常变化的因素虽然都与大地震面波的强弱、地质构造环境等有关,但机理不同。     

库车坳陷克拉2气田异常流体压力演化史

根据克拉2气田现今实测地层压力分析了异常高压发育的特征,并通过流体包裹体测试求取包裹体形成时期的古压力。计算结果表明:下白垩统和古近系库姆格列木群砂岩储层在距今8～6Ma(康村组沉积期末)时,古压力系数大致为1.09～1.18,发育过剩压力为4.6～9.6MPa的异常高压。在此基础上,以古、今压力数据为约束条件,利用数值模拟技术定量恢复出下白垩统与侏罗系异常流体压力的演化历史。研究发现:下白垩统储层流体压力经历了沉积型异常流体压力形成发展(白垩纪-库车组沉积期末)和沉积型异常流体压力萎缩—构造挤压型异常流体压力孕育(库车组沉积期末至今)两个阶段。康村组沉积早期沉积型超压开始出现,库车组沉积期末达到顶峰,过剩压力达40～50MPa;此后,在沉积型超压萎缩—构造挤压型超压孕育过程的耦合下,过剩压力曾降至25～30MPa,更新世起超压略有升高。侏罗系流体压力演化较为简单,吉迪克组沉积期开始出现超压,至库车组沉积期末达到高峰,此后异常高压逐渐萎缩。在克拉2气田的主要成藏时期(距今3～1Ma),烃源岩较储层具有更高的异常压力,源—储压力差为10～30MPa。