Tropical cyclone activity in global warming scenario

Research efforts focused on assessing the potential for changes in tropical cyclone activity in the greenhouse-warmed climate have progressed since the IPCC assessment in 1996. Vulnerability to tropical cyclones becoming more pronounced due to the fastest population growth in tropical coastal regions makes it practically important to explore possible changes in tropical cyclone activity due to global warming. This paper investigates the tropical cyclone activity over whole globe and also individually over six different ocean basins. The parameters like storm frequency, storm duration, maximum intensity attained and location of formation of storm have been examined over the past 30-year period from 1977 to 2006. Of all, the north Atlantic Ocean shows a significant increasing trend in storm frequency and storm days, especially for intense cyclones. Lifetime of intense tropical cyclones over south Indian Ocean has been increased. The intense cyclonic activity over north Atlantic, south-west Pacific, north and south Indian Ocean has been increased in recent 15 years as compared to previous 15 years, whereas in the east and west-north Pacific it is decreased, instead weak cyclone activity has been increased there. Examination of maximum intensity shows that cyclones are becoming more and more intense over the south Indian Ocean with the highest rate. The study of the change in the cyclogenesis events in the recent 15 years shows more increase in the north Atlantic. The Arabian Sea experiences increase in the cyclogenesis in general, whereas Bay of Bengal witnesses decrease in these events. Shrinking of cyclogenesis region occurs in the east-north Pacific and south-west Pacific, whereas expansion occurs in west-north Pacific. The change in cyclogenesis events and their spatial distribution in association with the meteorological parameters like sea surface temperature (SST), vertical wind shear has been studied for Indian Ocean. The increase in SST and decrease in wind shear correspond to increase in the cyclogenesis events and vice versa for north Indian Ocean; however, for south Indian Ocean, it is not one to one.     

Is Climate Change Shifting the Poleward Limit of Mangroves?

Ecological (poleward) regime shifts are a predicted response to climate change and have been well documented in terrestrial and more recently ocean species. Coastal zones are amongst the most susceptible ecosystems to the impacts of climate change, yet studies particularly focused on mangroves are lacking. Recent studies have highlighted the critical ecosystem services mangroves provide, yet there is a lack of data on temporal global population response. This study tests the notion that mangroves are migrating poleward at their biogeographical limits across the globe in line with climate change. A coupled systematic approach utilising literature and land surface and air temperature data was used to determine and validate the global poleward extent of the mangrove population. Our findings indicate that whilst temperature (land and air) have both increased across the analysed time periods, the data we located showed that mangroves were not consistently extending their latitudinal range across the globe. Mangroves, unlike other marine and terrestrial taxa, do not appear to be experiencing a poleward range expansion despite warming occurring at the present distributional limits. Understanding failure for mangroves to realise the global expansion facilitated by climate warming may require a focus on local constraints, including local anthropogenic pressures and impacts, oceanographic, hydrological, and topographical conditions.     

Assessment of vulnerability to seawater intrusion and potential remediation measures for coastal aquifers: a case study from eastern India

Seawater intrusion is a major threat to the rapidly depleting groundwater resources in the coastal areas of India. Groundwater-based irrigation, significant industrial development and rapid urbanization are some of the key contributors exacerbating the stress on groundwater resources. Vulnerability to seawater intrusion in the Ramanathapuram district of Eastern India is assessed here utilizing the GALDIT method, for a period of 10 years (2001–2010). Results revealed a drastic increase in percent area coverage under moderate vulnerability, from 19.5 to 53.88 %, between the years 2001 and 2010. On the contrary, areas classified as highly vulnerable underwent minor changes over the span of the study. Vulnerability of the study area was also analyzed for the year 2050 considering an average global mean sea level rise of 3.1 mm/year. Results from the analysis for the year 2050 showed that, almost, the entire study area (~97 %) was classified under moderate vulnerability. As a remedial measure to this imminent threat, favorable zones for artificial recharge were delineated on the basis of overlay analysis with weightage values for important controlling factors. Subsequently, the quantity of artificial recharge required to inhibit the intrusion of seawater, at specified favorable zones were estimated to be 674.87, 599.18 and 1,450.66 m³/year.     

Simulation of global warming effect on outdoor thermal comfort conditions

In the coming decades, global warming and increase in temperature, in different regions of the world, may change indoor and outdoor thermal comfort conditions and human health. The aim of this research was to study the effects of global warming on thermal comfort conditions in indoor ambiences in Iran. To study the increase in temperature, model for assessment of greenhouse-gas induced climate change scenario generator compound model has been used together with four scenarios and to estimate thermal comfort conditions, adaptive model of the American Society of Heating, Refrigerating and Air-conditioning Engineers has been used. In this study, Iran was divided into 30 zones, outdoor conditions were obtained using meteorological data of 80 climatological stations and changes in neutral comfort conditions in 2025, 2050, 2075 and 2100 were predicted. In accordance with each scenario, findings from this study showed that temperature in the 30 zones will increase by 2100 to between 3.4 °C and 5.6 °C. In the coming decades and in the 30 studied zones, neutral comfort temperature will increase and be higher and more intense in the central and desert zones of Iran. The low increase in this temperature will be connected to the coastal areas of the Caspian and Oman Sea in southeast Iran. This increase in temperature will be followed by a change in thermal comfort and indoor energy consumption from 8.6 % to 13.1 % in air conditioning systems. As a result, passive methods as thermal inertia are proposed as a possible solution.     

A fast intensity simulator for tropical cyclone risk analysis

Robust estimates of tropical cyclone risk can be made using large sets of storm events synthesized from historical data or from physics-based algorithms. While storm tracks can be synthesized very rapidly from statistical algorithms or simple dynamical models (such as the beta-and-advection model), estimation of storm intensity by using full-physics models is generally too expensive to be practical. Although purely statistical intensity algorithms are fast, they may not be general enough to encompass the effects of natural or anthropogenic climate change. Here we present a fast, physically motivated intensity algorithm consisting of two coupled ordinary differential equations predicting the evolution of a wind speed and an inner core moisture variable. The algorithm includes the effects of ocean coupling and environmental wind shear but does not explicitly simulate spatial structure, which must be handled parametrically. We evaluate this algorithm by using it to simulate several historical events and by comparing a risk analysis based on it to an existing method for assessing long-term tropical cyclone risk. For simulations based on the recent climate, the two techniques perform comparably well, though the new technique does better with interannual variability in the Atlantic. Compared to the existing method, the new method produces a smaller increase in global tropical cyclone frequency in response to global warming, but a comparable increase in power dissipation.     

Forecasting of cyclone Viyaru and Phailin by NWP-based cyclone prediction system (CPS) of IMD – an evaluation

An objective NWP-based cyclone prediction system (CPS) was implemented for the operational cyclone forecasting work over the Indian seas. The method comprises of five forecast components, namely (a) Cyclone Genesis Potential Parameter (GPP), (b) Multi-Model Ensemble (MME) technique for cyclone track prediction, (c) cyclone intensity prediction, (d) rapid intensification, and (e) predicting decaying intensity after the landfall. GPP is derived based on dynamical and thermodynamical parameters from the model output of IMD operational Global Forecast System. The MME technique for the cyclone track prediction is based on multiple linear regression technique. The predictor selected for the MME are forecast latitude and longitude positions of cyclone at 12-hr intervals up to 120 hours forecasts from five NWP models namely, IMD-GFS, IMD-WRF, NCEP-GFS, UKMO, and JMA. A statistical cyclone intensity prediction (SCIP) model for predicting 12 hourly cyclone intensity (up to 72 hours) is developed applying multiple linear regression technique. Various dynamical and thermodynamical parameters as predictors are derived from the model outputs of IMD operational Global Forecast System and these parameters are also used for the prediction of rapid intensification. For forecast of inland wind after the landfall of a cyclone, an empirical technique is developed. This paper briefly describes the forecast system CPS and evaluates the performance skill for two recent cyclones Viyaru (non-intensifying) and Phailin (rapid intensifying), converse in nature in terms of track and intensity formed over Bay of Bengal in 2013. The evaluation of performance shows that the GPP analysis at early stages of development of a low pressure system indicated the potential of the system for further intensification. The 12-hourly track forecast by MME, intensity forecast by SCIP model and rapid intensification forecasts are found to be consistent and very useful to the operational forecasters. The error statistics of the decay model shows that the model was able to predict the decaying intensity after landfall with reasonable accuracy. The performance statistics demonstrates the potential of the system for improving operational cyclone forecast service over the Indian seas.     

Track prediction of Indian Ocean cyclones using Lagrangian advection model

A new model has been developed for track prediction of Indian Ocean cyclones. The model utilizes environmental steering flow using the forecasts from a high-resolution global model and the effect due to earth??s rotation (the beta-effect) to determine the future movement of cyclone. A new approach based on vertical profile of potential vorticity is used to determine weights for different vertical levels for computation of mean steering current. Despite the fact that the model is based on the dynamical framework, the operational cost and time for running the model is only a fraction of what is needed by a normal numerical weather prediction model. This new approach will enhance flexibility in defining the initial position of the cyclone in the model, and also, it is possible to create a large ensemble of predicted tracks to assess the impact of the uncertainty of initial cyclone position on the predicted tracks. The performance of the model for ten cyclones, viz. GONU (02?C08 Jun, 2007), SIDR (11?C16 November, 2007), NARGIS (27 Apr?C04 May, 2008), RASHMI (25?C27 October, 2008) KHAI-MUK (14?C16 November, 2008), NISHA (25?C27 November, 2008), SEVEN (04?C08 December, 2008), BIJLI (14?C18 April, 2009), AILA (23?C26 May, 2009), and PHYAN (09?C11 November, 2009), have been tested in the present study. The forecast errors of the present model have been computed with respect to the Joint Typhoon Warning Center best track analysis positions. The forecast skill improvement (mean of ten cyclones) of the model with respect to the Climatology and Persistence (CLIPER) statistical model varies from 7 to 67?% between 12 and 72?h.     

A Comparative Research on Climatic Characteristics of Jianghuai Cyclones in Rainfall Season between Warming and Cooling Stages

By EOF, Power spectrum and nonlinear mapping methods, the temperature time series of May to July in Jianghuai river basins from 1948-2014 (67 years) were objectively divided into several climate stages. The time series were divided into three climate stages with similar lengths: the stage with its air temperature trend going downwards stage (1948-1970); the stage with its air temperature trend going upwards (1971-1994) and the stage with its air temperature trend going gentle upwards (1995-2014). Their climate characteristics can be quantified by a special climate index. Then, the statistic characteristics of Jianghuai cyclones in the three climate stages were compared with the cooling or warming trends. The results showed that characteristic evolutions of the frequency of yearly average of Jianhuai cyclones, the cyclones with their life cycles in the area longer than 48h, the cyclones with three types of thickness, shallow and bottom shapes classified according to the cyclone height, the cyclones with three kinds of zonal, meridional, and circular trajectory, responded to the temperature changing trends in the three climate stages. The cooling trends of the stage temperature restrained the activity of Jianghuai cyclones, and the warming trends of the stage temperature promoted the cyclone’s development, maintaining, activity, and also led cyclone moving towards to north further. The composite analysis of cyclone structures showed that the evolution characteristics in the center intensity, temperature grads, the maxima velocity of jet of the cyclones, and the intensity, length and position of the vapor flux passage of the Jianghuai cyclones, also the intensity, thickness, the positions of the warm and cold air masses within the cyclones, all responded to the trend change of stage temperature including cooling, warming and gentle warming. The results show clearly that temperature cooling reduces the intensity of cyclone structures and restrains the activity of cyclones in the temperatures trend down stage. The temperature warming enhances the stable development and strengthening of cyclone structure,and maintains the activity of cyclones in the temperature warming stages.     

全球变化——海洋地学的热点问题

文章对当今海洋地球科学中对全球环境变化有影响的气候变暖、板块构造运动、环境地质和矿产资源开发等热点问题进行了阐述。近百年来，世界气温变化反映全球变暖的趋势。气候变暖引起的海平面上升和厄尔尼诺现象将对沿海国家近岸地区人民的生产和生活带来极大的危害和巨大的经济损失。８０年代以来，全球板块构造运动及其驱动力成为科学家研究的热点；沿岸国家海岸带海陆交互地区的开发活动和日益严重的污染对海洋生态环境造成极大危害。文章亦分析了海洋矿产资源开发的前景和海洋地球科学面临的重要课题，提出２１世纪我国海洋地质调查与研究的主要任务     

The role of natural ecosystems and socio-economic factors in the vulnerability of coastal villages to cyclone and storm surge

Vulnerability assessment due to tropical storms has been attempted for larger spatial units, and the roles played by natural ecosystems like mangroves or hydrological variables like proximity to rivers or various socio-economic factors determining economic well-being are rarely taken into account. During cyclones, evacuation and relief works are undertaken at the village level, and thus, knowledge of relative vulnerability of the coastal villages is important to the policy makers. The paper studies 262 villages lying within a 10?km of the coast in one of the most cyclone prone districts of India and estimates the probability of expected human fatality due to severe cyclone for these villages. Such probabilities are calculated from a cyclone impact (human deaths) function where a wide range of factors including natural ecosystems are used to control for the exposure and adaptive capacity of the villages. The results show villages established in mangrove habitat areas (after clearing the forest) and those with more marginal workers (without any regular jobs) to face a very high death risk. In contrast, villages situated in the leeward side of existing mangrove forest or near a major river are seen to be facing a much lower risk of deaths. The results have important implications like conserving mangroves in cyclone-prone areas, priority evacuation of villages established in the mangrove habitat before a high-intensity cyclone, etc., for cyclone hazard management.     

Vulnerability to natural disasters in Serbia: spatial and temporal comparison

The frequency of natural disasters and the extent of their consequences at a global level are constantly increasing. This trend is partially caused by increased population vulnerability, which implies the degree of population vulnerability due to high-magnitude natural processes. This paper presents an analysis of vulnerability to natural disaster in Serbia in the second half of the twentieth and the early twenty-first century. Vulnerability changes were traced on the basis of demographic–economic indicators derived from statistical data for local government units (municipalities) provided by the Statistical Office of the Republic of Serbia. Calculations were performed in the geographical information system environment. The results of the study show that spatial and temporal vulnerability variations are causally correlated with changes in the selected components. Significant rise of vulnerability is related to urban areas, while lower values are characteristic for other areas of Serbia; this is primarily a consequence of different population density.     

A knowledge-driven GIS modeling technique for groundwater potential mapping at the Upper Langat Basin, Malaysia

The aim of this paper is to use a knowledge-driven expert-based geographical information system (GIS) model coupling with remote-sensing-derived parameters for groundwater potential mapping in an area of the Upper Langat Basin, Malaysia. In this study, nine groundwater storage controlling parameters that affect groundwater occurrences are derived from remotely sensed imagery, available maps, and associated databases. Those parameters are: lithology, slope, lineament, land use, soil, rainfall, drainage density, elevation, and geomorphology. Then the parameter layers were integrated and modeled using a knowledge-driven GIS of weighted linear combination. The weightage and score for each parameter and their classes are based on the Malaysian groundwater expert opinion survey. The predicted groundwater potential map was classified into four distinct zones based on the classification scheme designed by Department of Minerals and Geoscience Malaysia (JMG). The results showed that about 17% of the study area falls under low-potential zone, with 66% on moderate-potential zone, 15% with high-potential zone, and only 0.45% falls under very-high-potential zone. The results obtained in this study were validated with the groundwater borehole wells data compiled by the JMG and showed 76% of prediction accuracy. In addition statistical analysis indicated that hard rock dominant of the study area is controlled by secondary porosity such as distance from lineament and density of lineament. There are high correlations between area percentage of predicted groundwater potential zones and groundwater well yield. Results obtained from this study can be useful for future planning of groundwater exploration, planning and development by related agencies in Malaysia which provide a rapid method and reduce cost as well as less time consuming. The results may be also transferable to other areas of similar hydrological characteristics.     

Analysis of human risks due to dam break floods—part 2: application to Tangjiashan landslide dam failure

The Tangjiashan landslide dam was formed during the Ms8.0 Wenchuan earthquake in 2008 and posed high risks to 1.2?million people downstream the dam. A human risk analysis model (HURAM) reported in the companion paper is applied to evaluate the human risk in the Tangjiashan landslide dam failure. The characteristics of this landslide dam are introduced first. The breaching parameters in two cases (i.e., the actual case and a high erodibility case) are predicted with a physically based model, and the flood routing processes in these two cases are simulated using numerical analysis. The population at risk downstream of the landslide dam is then obtained based on the results of the flood routing simulations. Subsequently, the human risks are analyzed with HURAM using Bayesian networks. Fourteen influence parameters and their interrelationships are considered in a systematic structure in the case study. A change in anyone of them may affect the other parameters and leads to loss of life. HURAM allows not only cause-to-result inference, but also result-to-cause inference by updating the Bayesian network with specific information from the study case. The uncertainties of the parameters and their relationships are studied both at the global level using multiple sources of information and at the local level by updating the prior probabilities.     

Improved groundwater vulnerability mapping for the karstic chalk aquifer of south east England

The Cretaceous age Chalk of south east England forms an important aquifer. Within chalk the storage and transmission of groundwater is enhanced by subsurface karstic weathering. The case study presented in this paper demonstrates that current approaches to assessing groundwater vulnerability to pollution and delineating source protection zones are flawed, as they do not take proper account of the karstic nature of chalk.Improved techniques, based on understanding the geological and geomorphological controls of karst development in chalk, are proposed to overcome the shortcomings of published groundwater vulnerability maps. The results also demonstrate the inadequacies of current groundwater modelling approaches for defining source protection zones. The techniques follow European Commission research recommendations by taking account of recharge, presence of overlying cover deposits, the nature of chalk karst and the way in which it influences the flow of groundwater. The approach described allows for better informed decisions to be made about chalk aquifer management to ensure adequate protection and conservation of groundwater. For example, the published groundwater vulnerability map shows Lambeth Group deposits classified as being a minor aquifer of low groundwater vulnerability in the chosen study area. However, by applying the new techniques, they are classified as having an Aquifer Vulnerability Rating of moderate to very high, when taking the karstic development of the underlying chalk into account.     

Maximum Storm Surge Curve Due to Global Warming for the European North Sea Region During the 20th–21st Century

Computations of storm surges during the 20th century needs to incorporate globalwarming of about 0.6 °C ± 0.2 °C (IPCC, 2001). In order totake this global warming into consideration, the development of all storm surgesoccurred during the 20th century have been analysed. The study comprises determiningto what degree the storm surge curve and storm surge level depend on each other. Thisfact can be used to calculate a maximum storm surge curve and each single storm surgeevent can be summarised. The tendency of the surge and wind parameters do not showthat this maximum storm surge levels in the 20th century will occur earlier than predicted, however, the global warming of 0.6 °C will extend the duration of the mean storm surge curve.     

全球气候变化及其影响因素研究进展综述

概述了全球气候变化问题提出的科学背景,总结了引起气候变化的原因,客观分析了引起不同时间尺度气候变化的各种自然因素,透视了人类活动对气候变化的影响程度,讨论了应该如何理解当今全球气候变暖问题。同时,还综述了气候变化研究中的学术分歧和科学困惑。     

May 2003 Disaster in Sri Lanka and Cyclone 01-B in the Bay of Bengal

Heavy rainfall deluged South-Western Sri Lanka between the 11th and19th of May 2003 and led to its worst disaster in 50 years. Floods andlandslides claimed 260 lives. The World Meteorological Organizationcited it as evidence for the increase of anomalous climatic extremes inrecent years. Here, a meteorological analysis is presented of this disasteras part of a sustained effort to undertake meteorological applications fordisaster management. There were intense low-level westerlies over SriLanka related to cyclone 01-B that made its way across the Bay of Bengalat least 700 km away. The southeastwardly traverse of the cyclone wasstalled for a few days by anomalous north-westerly geostrophic windsver South Asia. Here, it is argued that orographic rainfall induced bythis stalled cyclone and seasonal inter-tropical convergence zone cloudbands over Sri Lanka led to the deluge. The trajectory of the cyclone wasremote from Sri Lanka and this led to no cyclone hazard warnings beingissued. No cyclones have made landfall in Sri Lanka in May in the last100 years. This study shows that one must exercise vigilance not only inthe path of the cyclone but also remotely due to the modulation of thecyclone by other atmospheric phenomenon and topographic features.This flood may have been predicted with contemporary local area weatherprediction models and this example points to the need for the developmentof local area weather prediction models as part of disaster warning systems.This study also demonstrates the use of meteorological diagnostics forpost-event analysis of hydrometeorology of disaster events.     

A database for worldwide seismicity quantification

The first step in a seismicity analysis usually consists of defining the seismogenic units, seismic zones or individual faults. The worldwide delimitation of these zones involves an enormous effort and is often rather subjective. Also, a complete recording of faults will not be available for a long time yet. The seismicity model presented in this paper therefore is not based on individually defined seismic zones but rather on the assumption that each point in a global 1/2° grid of coordinates represents a potential earthquake source. The corresponding seismogenic parameters are allocated to each of these points. The earthquake occurrence frequency, one of the most important parameters, is determined purely statistically by appropriately spreading out the positions of past occurrences. All the other significant seismicity characteristics, such as magnitude-frequency relations, maximum possible magnitude and attenuation laws including the dependence on focal depth are determined in a global 1/2° grid of co-ordinates. This method of interpreting seismicity data allows us to establish a transparent, sufficiently precise representation of seismic hazard which is ideally suited for computer-aided risk analyses.     

Biophysical impacts of climate change on bird populations and migration in Lithuania

This paper presents data obtained from studies of the dependence of different migratory processes - spring arrival, migratory take-off, spring and autumn en route migration–upon climate change in Lithuania. The article confirms the impact of global climate warming on different breeding bird species and populations, changes in their ranges and population state, and their staging and wintering areas. The list of bird species which are shifting their ranges north-eastward or eastward in the Baltic region under the influence of global warming is presented. It was established that the impact of global climate change upon birds of terrestrial and wetland complexes is more evident than upon waterfowl. Attention is focussed on the practical importance of the global climate change impact on environmental protection and different branches of the economy. This revised version was published online in July 2006 with corrections to the Cover Date.