Simulation of Bay of Bengal Tropical Cyclones with WRF Model: Impact of Initial and Boundary Conditions     

U. C. Mohanty  Krishna K. Osuri  A. Routray  M. Mohapatra  Sujata Pattanayak 《Marine Geodesy》2013,36(4):294-314

An attempt is made to delineate the relative performances and credentials of GFS, FNL, and NCMRWF global analyses/forecast products as initial and boundary conditions (IBCs) to the WRF-ARW model in the simulation of four Bay of Bengal tropical cyclones (TCs). The results suggest that FNL could simulate horizontal advection of vorticity maxima at 850 hPa; hence, the tracks are more realistic with least errors as compared to GFS and NCMRWF. The mean landfall errors for 24-, 48-, and 72-hour forecasts are 73, 41, and 72 km, respectively. The TC intensity is well captured by NCMRWF IBCs, as it could predict 850 hPa vorticity maxima. The 24-hour accumulated rainfall is well simulated with FNL, and equitable threat score is more than 0.2 up to 100 mm with minimum bias.  相似文献   

Petrology,genesis and geodynamic implication of the Mesoproterozoic–Late Cretaceous Timmasamudram kimberlite cluster,Wajrakarur field,Eastern Dharwar Craton,southern India     

Ashish Dongre  N.V. Chalapathi Rao  K.S. Viljoen  B. Lehmann 《地学前缘(英文版)》2017,8(3):541-553

New mineralogical and bulk-rock geochemical data for the recently recognised Mesoproterozoic(ca.1100 Ma) and late Cretaceous(ca.90 Ma) kimberlites in the Timmasamudram cluster(TKC) of the Wajrakarur kimberlite field(WKF),Eastern Dharwar Craton,southern India,are presented.On the basis of groundmass mineral chemistry(phlogopite,spinel,perovskite and clinopyroxene),bulk-rock chemistry(SiO_2.K_2O,low TiO_2.Ba/Nb and La/Sm),and perovskite Nd isotopic compositions,the TK-1(macrocrystic variety) and TK-4(Macrocrystic variety) kimberlites in this cluster are here classified as orangeites(i.e.Group Ⅱ kimberlites),with geochemical characteristics that are very similar to orangeites previously described from the Bastar Craton in central India,as well as the Kaapvaal Craton in South Africa.The remaining kimberlites(e.g.,TK-2,TK-3 and the TK-1 microcrystic variant),are more similar to other 1100 Ma,Group Ⅰ-type kimberlites of the Eastern Dharwar Craton,as well as the typical Group Ⅰkimberlites of the Kaapvaal Craton.Through the application of geochemical modelling,based on published carbonated peridotite/melt trace element partition coefficients,we show that the generation of the TKC kimberlites and the orangeites results from low degrees of partial melting of a metasomatised,carbonated peridotite.Depleted mantle(T_(DM)) Nd perovskite model ages of the 1100 Ma Timmasamudram kimberlites show that the metasornatic enrichment of their source regions are broadly similar to that of the Mesoproterozoic kimberlites of the EDC.The younger,late Cretaceous(ca.90 Ma) TK-1(macrocrystic variant)and TK-4 kimberlites,as well as the orangeites from the Bastar Craton,share similar Nd model ages of1100 Ma,consistent with a similarity in the timing of source enrichment during the amalgamation of Rodinia supercontinent.The presence of late Cretaceous diamoncliferous orangeite activity,presumably related to the location of the Marion hotspot in southern India at the time,suggests that thick Iithosphere was preserved,at least locally,up to the late Cretaceous,and was not entirely destroyed during the breakup of Gondwana,as inferred by some recent geophysical models.  相似文献   

An empirical relation of daytime equatorial total electron content with equatorial electrojet in the Indian zone     

Rajat Acharya  Bijoy Roy  M.R. Sivaraman  Ashish Dasgupta 《Journal of Atmospheric and Solar》2010,72(9-10):774-780

The variability of Total Electron Content (TEC) at Trivandrum, located within equatorial anomaly region at the dip equator, with respect to a reference level derived from the TEC measurements at Shimla, located outside the region has been studied during low solar activity period. Chapman function is assumed to hold good for regions outside the anomaly extent. It shows that the difference of total measured TEC at the equator from the derived reference is highly correlated with equatorial electrojet. The observations conform to the previous investigations and are interpreted in light of established relations. A stochastic relationship with electrojet is derived and validated.  相似文献   

Neo-deterministic seismic hazard scenarios for India—a preventive tool for disaster mitigation     

Imtiyaz A. Parvez  Andrea Magrin  Franco Vaccari  Ashish  Ramees R. Mir  Antonella Peresan  Giuliano Francesco Panza 《Journal of Seismology》2017,21(6):1559-1575

Current computational resources and physical knowledge of the seismic wave generation and propagation processes allow for reliable numerical and analytical models of waveform generation and propagation. From the simulation of ground motion, it is easy to extract the desired earthquake hazard parameters. Accordingly, a scenario-based approach to seismic hazard assessment has been developed, namely the neo-deterministic seismic hazard assessment (NDSHA), which allows for a wide range of possible seismic sources to be used in the definition of reliable scenarios by means of realistic waveforms modelling. Such reliable and comprehensive characterization of expected earthquake ground motion is essential to improve building codes, particularly for the protection of critical infrastructures and for land use planning. Parvez et al. (Geophys J Int 155:489–508, 2003) published the first ever neo-deterministic seismic hazard map of India by computing synthetic seismograms with input data set consisting of structural models, seismogenic zones, focal mechanisms and earthquake catalogues. As described in Panza et al. (Adv Geophys 53:93–165, 2012), the NDSHA methodology evolved with respect to the original formulation used by Parvez et al. (Geophys J Int 155:489–508, 2003): the computer codes were improved to better fit the need of producing realistic ground shaking maps and ground shaking scenarios, at different scale levels, exploiting the most significant pertinent progresses in data acquisition and modelling. Accordingly, the present study supplies a revised NDSHA map for India. The seismic hazard, expressed in terms of maximum displacement (Dmax), maximum velocity (Vmax) and design ground acceleration (DGA), has been extracted from the synthetic signals and mapped on a regular grid over the studied territory.  相似文献   

Influence of rooftop telecommunication tower on set back-step back building resting on different ground slopes     

Thakur  Amit  Ashish  Deepankar Kumar  Verma  Surender Kumar 《地震工程与工程振动(英文版)》2019,18(2):351-362

In the hilly region due to scarcity of the plain area, buildings like set back-step back are more often used and also as a big surge in the telecommunication industries, rooftop tower adaptation is very common story nowadays. In the present study an analogy has been drawn to find out the influence of the rooftop telecommunication tower on the setback-step back building resting on ground at 20° and 30° slopes. A dynamic analysis has been performed and compared on the 4 legged angled section telecommunication tower which is located on the roof top of set back-step back building by varying positions of tower with the existing host structure built up on ground slope of 20° and 30° in both directions(X and Y).  相似文献   

Post-Cyclone Sidr nutritional status of women and children in coastal Bangladesh: an empirical study     

Shitangsu Kumar Paul  Bimal Kanti Paul  Jayant K. Routray 《Natural Hazards》2012,64(1):19-36

Cyclone Sidr, a Category 4 storm, struck the southwestern coast of Bangladesh on November 15, 2007, causing 3,406 deaths, 2.51 million acres of crop damage, and aggregated damage of US$1.7 billion. It significantly damaged household food availability and increased post-cyclone nutritional insecurity. This study assesses the nutritional status of household and explores influences of various socioeconomic variables on nutritional security. More specifically, it explores the impact of the cyclone on short-term nutritional status of women of reproductive age and children under 5?years. For this study, 331 households living in three villages devastated by Cyclone Sidr were selected. The nutritional status of women of reproductive age was measured based on body mass index, and that of children aged 6?C59?months was measured based on weight-for-height (wasting), height-for-age (stunting), and weight-for-age (underweight). This study found that the nutritional status, along with other household characteristics, of the study groups was not remarkably different across the three selected villages. Findings of this study further suggest that the nutritional security situation was not much changed in the post-cyclone period compared with the pre-cyclone period primarily because of rapid and effective distribution of essential food items among cyclone survivors by the government of Bangladesh along with donor and other organizations. However, nutritional insecurity was more prevalent in the island village relative to inland and coastline villages. Similarly, fishermen were found to be the most vulnerable to nutritional insecurity in the post-cyclone period. Several recommendations are made to improve food aid distribution in the aftermath of a cyclone.  相似文献   

Determinants of farmers’ choice of coping and adaptation measures to the drought hazard in northwest Balochistan,Pakistan   总被引：2，自引：0，他引：2  

Muhammad Ashraf  Jayant K. Routray  Muhammad Saeed 《Natural Hazards》2014,73(3):1451-1473

This study identifies the coping and adaptation behavior of the farm households and also examines the factors that influence farmers’ choice for drought-induced adaptation strategies. The study employs a multivariate probit model on 215 farm households’ survey data from northwest Balochistan, Pakistan. The findings reveal that the farmers have shown considerable fortitude in coping with the impacts of drought on their agro-based practices and employed several adaptation initiatives both at on-farm and off-farm levels. These include crop management, water management, adjustment in agricultural inputs, income diversification, economization of expenditure and consumption smoothing, migrating to other places to seek alternative sources of income, assets depletion, and borrowing. Empirically, it is depicted that landholding, annual income, livestock ownership, credit access, farmer-to-farmer extension, GOs/NGOs support increase the probability of farmers’ decision to cope and adapt better with drought hazard. This study implies for specific policy and practice-oriented solutions in order to cope with and adapt in drought situation.  相似文献   

Analytical models for the groundwater tidal prism and associated benthic water flux     

Jeffrey N. King  Ashish J. Mehta  Robert G. Dean 《Hydrogeology Journal》2010,18(1):203-215

The groundwater tidal prism is defined as the volume of water that inundates a porous medium, forced by one tidal oscillation in surface water. The pressure gradient that generates the prism acts on the subterranean estuary. Analytical models for the groundwater tidal prism and associated benthic flux are presented. The prism and flux are shown to be directly proportional to porosity, tidal amplitude, and the length of the groundwater wave; flux is inversely proportional to tidal period. The duration of discharge flux exceeds the duration of recharge flux over one tidal period; and discharge flux continues for some time following low tide. Models compare favorably with laboratory observations and are applied to a South Atlantic Bight study area, where tide generates an 11-m³ groundwater tidal prism per m of shoreline, and drives 81 m³ s?^?1 to the study area, which describes 23% of an observational estimate. In a marine water body, the discharge component of any oscillatory benthic water flux is submarine groundwater discharge. Benthic flux transports constituents between groundwater and surface water, and is a process by which pollutant loading and saltwater intrusion may occur in coastal areas.  相似文献   

Household response to cyclone and induced surge in coastal Bangladesh: coping strategies and explanatory variables     

Shitangsu Kumar Paul  Jayant K. Routray 《Natural Hazards》2011,57(2):477-499

The purpose of this research is to explore indigenous coping strategies and identify underlying demographic, socio-economic and other relevant variables that influence the adoption of coping strategies in three distinct cyclone-prone coastal villages of Bangladesh. The study finds that cyclones and induced surges are a recurrent phenomenon in coastal Bangladesh; hence people are used to adjusting their lifestyle and adopting their own coping strategies intelligently. Adoption of a particular set of coping strategies depends not only on the magnitude, intensity and potential impacts of the cyclone and induced surge, but also age, gender, social class, dissemination of early warning information, locational exposure, external assistance, social protection and informal risk sharing mechanisms within the community. Indigenous cyclone disaster prevention and mitigation strategies significantly minimize the vulnerability of the people. Under extreme situations, when such disasters surpass the shock-bearing capacity of the victims, informal risk sharing mechanisms through social bonding and social safety-nets become vital for short-term survival and long-term livelihood security. Therefore, proper monitoring and understanding of local indigenous coping strategies are essential in order to target the most vulnerable groups exposed to disasters. Additionally, proper dissemination of early warning and government and non-government partnerships for relief and rehabilitation activities should be prioritized to ensure pro-poor disaster management activities. The study also recommends effective monitoring of the impact of aid to ensure corrective measures to avoid the development of relief dependency by disaster victims.  相似文献   

Towards dynamic catchment modelling: a Bayesian hierarchical mixtures of experts framework     

Lucy Marshall  David Nott  Ashish Sharma 《水文研究》2007,21(7):847-861

Despite the abundance of existing hydrological models, there is no single model that has been identified as performing consistently over the range of possible catchment types and catchment conditions. An attractive alternative to selecting a single model is to combine the results from several different hydrological models, thereby providing a more appropriate representation of model uncertainty than is the case otherwise. Methods based on Bayesian statistical techniques provide an ideal means to compare and combine competing models, as they explicitly account for model uncertainty. Bayesian model averaging is one such alternative that combines individual models by weighting models proportional to their respective posterior probability of selection. However, the necessity of having fixed weights for each model over the entire length of the simulation period means that the relative usefulness of different models at different times is not considered. The hierarchical mixtures of experts (HME) framework is an appealing extension of the model averaging framework that allows the individual model weights to be estimated dynamically. Consequently, a model more capable at simulating low flow characteristics attains a higher weight (probability) when such conditions are likely, switching over to a lower weight when catchment storage increases. In this way, different models apply in different hydrological states, with the probability of selecting each model being allowed to depend on relevant antecedent condition characteristics. HME models provide additional flexibility compared with simple combinations of models, by allowing the way that model predictions are combined to depend on predictor variables. Thus, for hydrological models, the ‘switch’ from one model to another can depend on the existing catchment condition. This new modelling framework is applied using a simple conceptual model to 10 selected Australian catchments. The study regions are chosen to vary considerably in terms of size, yield and location. Results from this application are compared with the alternative where a single fixed model structure is applied. Comparison of the model simulations using the maximum log‐likelihood and the Nash‐Sutcliffe coefficient of efficiency show that more variance in streamflow was explained by the HME model, compared with the conceptual model alone for each of the catchments investigated. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献