Identification and assessment of heavy rainfall–induced disaster potentials in Taipei City

With increasing threat to lives and properties, identifying and assessing disaster potentials has become necessary and prior for effective disaster preparation and rescue planning. This study first introduces practical methods currently used in Taipei City, Taiwan, to identify and assess heavy rainfall–induced potential risks on flood, debris flow, and landslide. The identified disaster potential information is further applied to a series of deterministic and probabilistic risk analyses using Shilin District of Taipei City as a case study. The deterministic risk analyses are conducted to evaluate the impact of various heavy rainfall intensities on the residents. The probabilistic risk analyses are performed to establish risk curves for the population affected by heavy rainfall–induced hazards. The risk curve represents the relationships between the affected population and the annual exceedance probability. This study found the annual exceedance probability is very sensitive to the assumed coefficients of variation of the affected population. It is recommended historical statistical data on the correlation between affected population and rainfall intensity should be recorded and compiled in order to assess the actual probability distribution function of the affected population. Risk analysis results are further applied to assess the community evacuation capacity in this district. Last, short-term and long-term mitigation strategies and recommendations are discussed.     

The Inversion Problem of Phase Travel Time Perturbations in Acoustic Imaging

The three-dimensional distribution of change in phase travel time of an active region below the solar surface can be constructed with the technique of acoustic imaging. The interpretation of the distribution of measured phase travel time perturbation suffers from the finite spatial resolution of the acoustic lenses. In the ray approximation, the phase travel time perturbation measured in acoustic imaging can be expressed as an integral of the product of the relative sound-speed perturbation and a kernel. Forward computations show that the vertical resolution of phase travel time perturbation is poor even in the ray approximation. In this study, we discuss the inversion of phase travel time perturbations to estimate the relative sound-speed perturbation with a regularized least-squares inversion method. The tests with model perturbations of sound speed show that the inversion reasonably recovers the distribution of the model perturbation. We also apply the inversion method to the measured phase travel time perturbation of active region NOAA 7981.     

The Origin of Glitches in Pulsars—Phase Oscillation between Anisotropic Superfluid and Normal State of Neutrons in Neutron Stars

Considering neutron star heating by magnetic dipole radiation from 3PF2 super-fluid neutron vortices inside the star, we propose a neutron phase oscillation model between the normal neutron Fermi fluid and the 3PF2 superfluid neutron vortices at the transition temperature of T_(trans) = (2-3)×108 K. With this model we can qualitatively explain most of the observations on pulsar glitches up to date.     

The status evaluation of the permafrost environment along the Chaida’er-Muli Railway in southern Qilian Mountains in northern Qinghai Province,China

Engineering construction has major influence on the permafrost environment.This paper analyzes the interaction between engineering construction and permafrost environment along the Chaidaer-Muli Railway(simply,CMR) based on the press-state-response(PSR) framework.The permafrost environmental system is divided into three subsystems,consisting of permafrost thermal stability,proneness to the freeze-thawing erosion and permafrost ecological fragility.Each subsystem considers its most important influencing factors.Catastrophe Progression Method(CPM) is applied to calculate the current environment condition along the railway.The result indicates that:(1) as far as the thermal stability is concerned,most sections along the CMR are mainly concentrated in rank Ⅲ(fair situation),and a few in Ⅱ(good situation) and Ⅳ(bad situation),respectively;(2) for the proneness tothe freeze-thawing erosion,the entire railway route falls largely in rank Ⅱ(good situation);(3) along the CMR,the ecological fragility of the permafrost environment is in rank Ⅱ(good situation),or slightly fragile;(4) overall,the permafrost environments along the CMR are in rank Ⅲ(fair situation) or Ⅱcondition(good situation).In general,the permafrost environment along the CMR is fair.It is mainly because a series of active measures of protecting permafrost were taken for stabilizing the CMR foundation soils.On the one hand,we should try our best to minimize the influences that engineering activities have exerted on ecology and environment,on the other hand,the positive measures have made improvements to prevent the permafrost environment from deterioration.     

Characterizing vertical contaminant distribution in a thick unconfined aquifer,Hanford site,Washington, USA

Drilling-intensive aquifer characterization techniques have been used to obtain depth-discrete water samples from a thick, hydrogeologically continuous unconfined aquifer system; groundwater results indicate that carbon tetrachloride contamination is widespread and extends deeper and at concentrations much higher than detected in monitoring networks at the water table. Carbon tetrachloride, a legacy waste, was used in the plutonium extraction process at the Hanford site in south-central Washington State. Vertical, depth-discrete groundwater samples were collected during well drilling throughout a 28-km² region to determine the concentration of carbon tetrachloride present as a dissolved phase in the aquifer. Results indicate that high concentrations of carbon tetrachloride, three orders of magnitude above the allowable regulatory limit, are present at depths greater than 25 m beneath the water table. In support of future efforts to remediate the carbon tetrachloride contamination, it is imperative to locate the remaining chemical inventory, determine the vertical as well as the lateral distribution of this contaminant and its physical form. Depth-discrete aquifer characterization throughout the uppermost-unconfined aquifer system is providing this information and improving the understanding of the contaminant distribution and the hydrogeologic framework through which it moves.

地质灾害遥感综合监测现状与展望

中国是世界上地质灾害最频繁、受灾最严重的国家之一.因此,利用更先进、更经济有效的手段对地质灾害进行监测和防治,成为我国的当务之急.通过总结目前中国以及世界上关于微波遥感、光学遥感和LiDAR等多源遥感数据在地质灾害领域的应用现状,包括地震、滑坡、地面沉降、地面塌陷、火山活动、冻土变化、冰川活动、土壤侵蚀、海岸侵蚀等地质灾害,对遥感在地质灾害方面的应用提出新的建议.     

An online model correction method based on an inverse problem: Part I—Model error estimation by iteration

Errors inevitably exist in numerical weather prediction (NWP) due to imperfect numeric and physical parameterizations. To eliminate these errors, by considering NWP as an inverse problem, an unknown term in the prediction equations can be estimated inversely by using the past data, which are presumed to represent the imperfection of the NWP model (model error, denoted as ME). In this first paper of a two-part series, an iteration method for obtaining the MEs in past intervals is presented, and the results from testing its convergence in idealized experiments are reported. Moreover, two batches of iteration tests were applied in the global forecast system of the Global and Regional Assimilation and Prediction System (GRAPES-GFS) for July-August 2009 and January-February 2010. The datasets associated with the initial conditions and sea surface temperature (SST) were both based on NCEP (National Centers for Environmental Prediction) FNL (final) data. The results showed that 6th h forecast errors were reduced to 10% of their original value after a 20-step iteration. Then, off-line forecast error corrections were estimated linearly based on the 2-month mean MEs and compared with forecast errors. The estimated error corrections agreed well with the forecast errors, but the linear growth rate of the estimation was steeper than the forecast error. The advantage of this iteration method is that the MEs can provide the foundation for online correction. A larger proportion of the forecast errors can be expected to be canceled out by properly introducing the model error correction into GRAPES-GFS.     

利用RADARSAT-2雷达卫星干涉数据监测输电通道地表形变应用研究

利用2018年3月18日—2018年9月26日获取的9景5 m分辨率的RADARSAT-2数据,采用小基线集差分干涉测量技术(SBAS-InSAR)对甘肃省平凉市某输电通道进行了地表形变监测研究.结果表明,在甘肃省平凉市某输电通道发现有多处明显的地表形变现象,监测期间累积形变量最大可达7.8 cm,距离最近杆塔约430 m.现场调查与差分干涉测量结果一致,表明利用RADARSAT-2雷达卫星干涉数据监测输电通道地表形变是有效的,在广域地质灾害监测方面具有广阔的应用前景.