强壮前沟藻(Amphidinium carterae Hulbert)在多重逆境条件下的生长和生理响应     

张珍妮  姜玥璐  李曼璐  魏鹏骥 《海洋与湖沼》2016,47(5):982-989

尽管单一逆境条件对浮游植物产生的影响已被广泛重视,然而对于多重逆境条件对藻细胞生长生理的研究仍有空白。本研究通过测定强壮前沟藻(Amphidinium carterae Hulbert)光密度(OD750)、叶绿素a含量(chl a)、光合作用效率(F_v/F_m)、碳氮比(C/N)等多个生理指标,分析其在9种环境下(常温光照、低温和低温黑暗三种物理环境,结合全营养、缺氮、缺磷三种营养状态)对多重逆境的生长和生理响应。研究结果表明,在多重逆境条件下,单一物理逆境因素(低温或黑暗)较氮限制或磷限制对藻细胞生长和生理的不利影响更为显著。营养限制并同低温环境双重作用对生物量和碳氮比产生显著性影响(P0.01)。此外,低温和黑暗条件耦合作用下,SYTOX Green染色强度处于较低水平,chl a稳定、F_v/F_m有所升高,强壮前沟藻在逆境环境下作为群体的衰亡得以缓解。  相似文献   

基于五种油源的中重度风化溢油的常规鉴定指标的应用效果评估     

贺世杰  王传远  李延太  于洪军  韩彬 《海洋学报(英文版)》2016,35(4):1-8

本文利用采集于我国三大油田的五种原油样品开展了长达210天的溢油风化模拟实验,并依据相对偏差和重复性限数学分析法,进行溢油风化过程分析和诊断比值应用效果评估。研究结果表明:经过210天的风化,溢油鉴定诊断比值发生明显改变;其中来源于萜烷、甾烷和多环芳烃的诊断比值变化率要远低于正构烷烃,可用于中长期风化溢油鉴定。此外,研究发现,在这些有效诊断比值中有4个变化率较小,相对偏差低于5%,保持了较好的稳定性,更适合于重度风化溢油鉴定。  相似文献   

海洋上层暖水在热带气旋迅速增强中的作用:基于台风威马逊(1409)的个例研究   总被引：5，自引：1，他引：4  

孙佳  左军成  凌征  闫运伟 《海洋学报(英文版)》2016,35(3):63-68

在登陆海南岛之前,台风威马逊在南海北部从热带风暴级别迅速增强成为超强台风。观测数据的分析结果显示,海洋上层的异常暖水在威马逊的迅速增强过程中扮演了重要的角色。威马逊期间,南海北部的海表面温度相比于气候态海表面温度暖很多。这部分异常暖水为威马逊提供了更多的能量,从而导致了威马逊的迅速增强。数值模拟结果进一步证明,南海北部的暖水在台风威马逊的迅速增强过程中起重要作用。如果没有这团异常暖水的影响,威马逊只增强25 hPa,仅为有暖水影响条件下增强程度的58.1%。  相似文献   

TTI介质拟声波方程数值模拟     

黄杰  杨国权  李振春  谷丙洛 《物探与化探》2018,(1):134-143

TTI介质qP波数值模拟方法因为考虑了倾角因素,可以比VTI介质qP波数值模拟方法更加准确地描述各向异性介质中地震波场的传播规律。文中用拟声波方程对TTI介质中的地震波场进行了高阶有限差分数值模拟,在改进衰减函数分布方式后,通过坐标变换,利用改进的完全匹配层(perfectly matched layer,PML)边界控制方程对波场边界进行吸收处理,取得了良好的效果;然后分析了拟声波方程数值模拟中的稳定性问题,并对波场中的伪横波进行压制。通过对不同模型的数值模拟,验证了文中使用的TTI介质拟声波波动方程的稳定性以及所采用的PML边界控制方程的可靠性和适用性。  相似文献   

Comparative Study of Hydrogen and Carbon Isotopic Composition of Gases Generated from the Pyrolysis of a Peat under Saltwater and Freshwater Conditions     

WU Yingzhong  DUAN Yi  ZHAO Yang  CAO Xixi  MA Lanhu  QIAN Yaorong  LI Zhongping  XING Lantian 《《地质学报》英文版》2018,92(5):1879-1887

To understand the influence of the diagenetic water medium on the isotopic compositions of thermogenic coalbed gas, both hydrous and anhydrous closed-system pyrolyses were performed at temperatures of 250°C to 650°C on an herbaceous marsh peat. Compared to the results of anhydrous pyrolysis, the hydrocarbon gases generated from hydrous pyrolyses have very different hydrogen isotopic compositions. However, the carbon isotopic compositions of the hydrocarbon gases became only slightly heavier in hydrous pyrolysis, compared to that from anhydrous pyrolysis. With the progress of thermal evolution from peat to a more advanced thermal maturity of vitrinite reflectance values (Ro) of 5.5% during the pyrolysis, the difference in the average δD value increased from 52‰ to 64‰ between the hydrous pyrolysis with saltwater and anhydrous pyrolysis and increased from 18‰ to 29‰ between the hydrous pyrolysis with freshwater and anhydrous pyrolysis, respectively. The difference in the average δ13C value was only 1‰–2‰ between the hydrous and anhydrous pyrolysis. The relationships between the δD values of the generated hydrocarbon gases and Ro values as well as among δD values of the hydrocarbon gas species are established. The close relationships among these parameters suggest that the water medium had a significant effect on the hydrogen isotopic composition and a minimal effect on the carbon isotopic composition of the hydrocarbon gases. The results of these pyrolyses may provide information for the understanding of the genesis of coalbed gas from herbaceous marsh material with the participation of different diagenetic water media.  相似文献   

黑龙江省两次温带气旋暴雪过程对比分析     

周显伟  赵宇  祝玉梅  娄德君 《冰川冻土》2018,40(6):1195-1206

利用多种资料对黑龙江省两次由江淮气旋和蒙古气旋合并引发的暴雪过程的水汽、热动力条件和中尺度特征进行了对比分析。结果表明：（1）两次暴雪过程都发生在北支槽和短波槽合并、北支槽北部有冷涡的背景下,850 hPa上低涡合并促使江淮气旋和蒙古气旋合并;气旋合并后,低空急流为降雪提供了充足水汽,强暖平流使气旋爆发性发展,导致降雪加强。（2）两次降雪过程都表现出逗点云系的合并发展,"1211 "暴雪过程中高层形成涡旋偏西,700 hPa低涡东部偏南风引导气旋北上西折,低空急流和地形共同作用使暖湿空气强烈辐合上升,产生对流云,暴雪发生在A类逗点云系的头部,降雪强度大,范围广;"1412"暴雪过程高空槽低涡位置偏东,700 hPa低涡东部西南风始终引导气旋向东北方向移动,近地面层具有冷垫,暴雪主要发生在B类气旋逗点云系头部西侧中低云团中,降雪范围和强度较"1211"过程小。（3）低层（0.3 km）冷空气侵入和中高层（5.5 km）转为偏北风对判断降雪开始和结束有很好的表征意义。（4）冷涡前部强高压脊使冷涡移动缓慢,从而延长了降水的持续时间,气旋移动路径与高压脊伸展方向密切相关。  相似文献   

The Key Supply Source of Long-Distance Moisture Transport for the Extreme Rainfall Event on July 21, 2012 in Beijing     

李娟  徐祥德  李跃清  赵天良  吴翀 《热带气象学报(英文版)》2021,27(1):34-47

In this study, the Weather Research and Forecasting (WRF) model and meteorological observation data were used to research the long-distance moisture transport supply source of the extreme rainfall event that occurred on July 21, 2012 in Beijing. Recording a maximum rainfall amount of 460 mm in 24 h, this rainstorm event had two dominant moisture transport channels. In the early stage of the rainstorm, the first channel comprised southwesterly monsoonal moisture from the Bay of Bengal (BOB) that was directly transported to north China along the eastern edge of Tibetan Plateau (TP) by orographic uplift. During the rainstorm, the southwesterly moisture transport was weakened by the transfer of Typhoon Vicente. Moreover, the southeasterly moisture transport between the typhoon and western Pacific subtropical high (WPSH) became another dominant moisture transport channel. The moisture in the lower troposphere was mainly associated with the southeasterly moisture transport from the South China Sea and the East China Sea, and the moisture in the middle troposphere was mainly transported from the BOB and Indian Ocean. The control experiment well reproduced the distribution and intensity of rainfall and moisture transport. By comparing the control and three sensitivity experiments, we found that the moisture transported from Typhoon Vicente and a tropical cyclone in the BOB both significantly affected this extreme rainfall event. After Typhoon Vicente was removed in a sensitivity experiment, the maximum 24-h accumulated rainfall in north China was reduced by approximately 50% compared with that of the control experiment, while the rainfall after removing the tropical cyclone was reduced by 30%. When both the typhoon and tropical cyclone were removed, the southwesterly moisture transport was enhanced. Moreover, the sensitivity experiment of removing Typhoon Vicente also weakened the tropical cyclone in the BOB. Thus, the moisture pump driven by Typhoon Vicente played an important role in maintaining and strengthening the tropical cyclone in the BOB through its westerly airflow. Typhoon Vicente was not only the moisture transfer source for the southwesterly monsoonal moisture but also affected the tropical cyclone in the BOB, which was a key supply source of long-distance moisture transport for the extreme rainfall event on July 21, 2012 in Beijing.  相似文献   

Influence of Sea Surface Temperature on the Predictability of Idealized Tropical Cyclone Intensity     

钟权加  李建平  李舒文  王羱  丁瑞强  张立凤 《热带气象学报(英文版)》2021,27(4):355-367

The role of sea surface temperature (SST) forcing in the development and predictability of tropical cyclone (TC) intensity is examined using a large set of idealized numerical experiments in the Weather Research and Forecasting (WRF) model. The results indicate that the onset time of rapid intensification of TC gradually decreases, and the peak intensity of TC gradually increases, with the increased magnitude of SST. The predictability limits of the maximum 10 m wind speed (MWS) and minimum sea level pressure (MSLP) are ~72 and ~84 hours, respectively. Comparisons of the analyses of variance for different simulation time confirm that the MWS and MSLP have strong signal-to-noise ratios (SNR) from 0-72 hours and a marked decrease beyond 72 hours. For the horizontal and vertical structures of wind speed, noticeable decreases in the magnitude of SNR can be seen as the simulation time increases, similar to that of the SLP or perturbation pressure. These results indicate that the SST as an external forcing signal plays an important role in TC intensity for up to 72 hours, and it is significantly weakened if the simulation time exceeds the predictability limits of TC intensity.  相似文献   

Assimilation of Polarimetric Radar Data Using an Ensemble Kalman Filter for the Analysis and Forecast of Tropical Storm Ewiniar     

黎慧琦  刘显通  肖辉  万齐林 《热带气象学报(英文版)》2021,27(2):94-108

This study explores the potential for directly assimilating polarimetric radar data (including reflectivity Z and differential reflectivity ZDR) using an ensemble Kalman filter (EnKF) based on the Weather Research and Forecasting (WRF) model to improve analysis and forecast of Tropical Storm Ewiniar (2018). Ewiniar weakened but brought about heavy rainfall over Guangdong, China after its final landfall. Two experiments are performed, one assimilating only Z and the other assimilating both Z and ZDR. Assimilation of ZDR together with Z effectively modifies hydrometeor fields, and improves the intensity, shape and position of rainbands. Forecast of 24-hour extraordinary rainfall ≥250 mm is significantly improved. Improvement can also be seen in the wind fields because of cross-variable covariance. The current study shows the possibility of applying polarimetric radar data to improve forecasting of tropical cyclones, which deserves more researches in the future.  相似文献   

Modelling tropical cyclone risks for present and future climate change scenarios using geospatial techniques     

Muhammad Al-Amin Hoque  Stuart Phinn  Chris Roelfsema  Iraphne Childs 《International Journal of Digital Earth》2018,11(3):246-263

Tropical cyclones and their devastating impacts are of great concern to coastal communities globally. An appropriate approach integrating climate change scenarios at local scales is essential for producing detailed risk models to support cyclone mitigation measures. This study developed a simple cyclone risk-modelling approach under present and future climate change scenarios using geospatial techniques at local scales, and tested using a case study in Sarankhola Upazila from coastal Bangladesh. Linear storm-surge models were developed up to 100-year return periods. A local sea level rise scenario of 0.34?m for the year 2050 was integrated with surge models to assess the climate change impact. The resultant storm-surge models were used in the risk-modelling procedures. The developed risk models successfully identified the spatial extent and levels of risk that match with actual extent and levels within an acceptable limit of deviation. The result showed that cyclone risk areas increased with the increase of return period. The study also revealed that climate change scenario intensified the cyclone risk area by 5–10% in every return period. The findings indicate this approach has the potential to model cyclone risk in other similar coastal environments for developing mitigation plans and strategies.  相似文献