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1.
It is generally believed that more than 100 tropical countries are suffering from desertification or land degradation as a result of climatic changes. There is also concern that the rising temperature would lead to further environmental degradation and cause economic, social and other environmental impacts (1) in the Middle East. This paper is a modest attempt to investigate temperature and rainfall data in three countries of the Middle East (Oman, Bahrain, and Sudan) to determine if any change has taken place in the weather conditions. The short term environmental impact of the GulfWar in 1991 has been included in the study.The study confirms that temperatures are rising and rainfall is decreasing in Oman (2, 3) and other two countries, leading to increasing desertification processes. Here, following Hume and Kelly (4) desertification is taken to mean degradation in dryland regions or the permanent decline in the potential of the land to support biological activity and hence human welfare. A brief geographical discussion of Oman, Bahrain, and Sudan precedes a detailed analysis of temperatures and rainfall regimen in all three countries.  相似文献   

2.
This study evaluates the synoptic features and environmental conditions of Brahmanbaria tornado event that caused 36 fatalities, 388 injuries and huge damages of properties on 22 March, 2013. Various factors for initiation of that terrific event are investigated through analysis JRA-55 reanalysis (50 km horizontal resolution) data and Multi-functional Transport Satellite images by Japan Meteorological Agency. In addition, radar images, radiosonde data and three hourly synoptic data of Bangladesh Meteorological Department are used to verify the reanalysis data. The genesis of the tornadic storm is identifiable in the most unstable part of the study region. The satellite observations are found to useful to identify the location of convection occurrence region. The half hourly satellite images identify that the convection initiation started at the convergence area and the systems intensify and organize by the continuous moisture supply from the Bay of Bengal. Lower-level convergence coupled with strong wind shear and humidity gradient lift moist air aloft to trigger deep convection and the severe storm occurred. Energy Helicity Index seems a good predictor parameter for this specific case study.  相似文献   

3.
This contribution explores the evolution of the flood risk in the Metropolitan Area of Barcelona (MAB; Northeast Spain) from 1981 to 2015, and how it has been affected by changes in land use, population and precipitation. To complete this study, we analysed PRESSGAMA and INUNGAMA databases to look for all the information related to the floods and flash floods that have affected the chosen region. The “Consorcio de Compensación de Seguros”, a state insurance company for extraordinary risks, provided data on economic damage. The extreme precipitation trend was analysed by the Fabra Observatory and El Prat-Airport Observatory, and daily precipitation data were provided by the State Meteorological Agency of Spain (AEMET) and the Meteorological Service of Catalonia (SMC). Population data were obtained from the Statistical Institute of Catalonia (IDESCAT). Changes in land use were estimated from the land use maps for Catalonia corresponding to 1956, 1993, 2000, 2005 and 2009. Prevention measures like rainwater tanks and improvements to the drainage system were also been considered. The specific case of Barcelona is presented, a city recognised by United Nations International Strategy for Disaster Reduction as a model city for urban resilience to floods. The evolution of flood events in the MAB does not show any significant trend for this period. We argue that the evolution in floods can be explained, at least in part, by the lack of trend in extreme precipitation indices, and also by the improvements in flood prevention measures.  相似文献   

4.
《Atmósfera》2014,27(4):377-384
Clean air is a basic requirement for human health and wellbeing. The Kenya Meteorological Department has established air pollution monitoring activities in various sites in Nairobi, at Dagoretti Corner meteorological station and at Mount Kenya. Different pollutants are measured including ozone. The increased concentration of greenhouse gases in the atmosphere has influenced the weather and climate. This study examined the variations of surface ozone over Dagoretti Corner, Nairobi for a 12-month period ending July 2013, exactly one year after the start of data acquisition. The trend was studied using time series analysis of ozone concentration on both an hourly and monthly basis. The ozone data was then combined with meteorological data and temperature to find correlations between the two. Overall, the air quality of Nairobi, represented by Dagoretti Corner meteorological station is good as compared to the World Meteorological Organization ozone standards. The highest concentration of ozone is observed in the afternoon and the minimum at dawn on a daily basis. On seasonal scale, the highest levels are recorded in the cold months. This information helps to reduce exposure to the gas and thus to reduce its impacts on living things. The study recommends the reduction of exposure to the gas during the times when it has been observed to be highest in order to minimize its impacts.  相似文献   

5.
The aim of the study is to evaluate the socio-economic contribution made by traditional industries in the arid and semiarid areas of the Sudan, and to assess their environmental impact. Two study areas, known for their diversified rural industries, have been chosen: the Mahmiya-Damar area as an example of riverine settlements, an non-riverine example of the Butana area (mainly El Subbagh region) in E Sudan.Rural industries in both areas were surveyed through direct interviews. A complete survey was made of the independent small industrial units, which are usually located in the markets, whilst a random-sample house survey was also carried out in both areas. In both areas the industries found have been grouped into seven classes.The survey, limited as it was in the residential areas, nonetheless revealed certain important characteristics of the production, distribution, and labour structure of the industries. It also revealed certain problems and difficulties which may lead in the end to a reduction of their role in these regions.  相似文献   

6.
The study of the history and dynamics of the migration of the Danagla to Port Sudan proves that they belong to the most active groups in the Sudan. Though they have completely dropped their agricultural background and adopted an entirely urban character they still have close contacts both to each other in town and to their home land. Their migration is, nontheless, a permanent one.  相似文献   

7.
天山乌鲁木齐河源1号冰川近雪面气象要素观测分析   总被引：1，自引：1，他引：0  
利用中国气象局乌鲁木齐沙漠气象研究所于2009年1月20日至12月31日在天山乌鲁木齐河源1号冰川冰雪表面实施大气科学观测实验观测取得的资料和同期大西沟气象站资料, 分析了1号冰川四季大气温度、风速、风向以及总辐射的变化特征, 对比、探讨了冰川尺度上冰雪表面与周边山地的辐射和地-气热量传输特性, 在此基础上揭示了二者气温、风速、大气湿度变化的差异及其成因. 研究表明: 1)由于冰川冰雪对太阳辐射的反射率高, 冰雪表面得到的净辐射和热量少, 使得冰川四季大气温度比大西沟站平均偏低2.9 ℃; 2)冰川与周边山地下垫面的不同, 引起太阳净辐射-温度场-气压场-风场的连锁变化, 造成冰川轴向风以下行偏南气流为主导, 法向风盛行偏东气流; 冰川夜间风速大于大西沟, 白天却小于大西沟风速; 3)冰川和大西沟大气含水量较高, 相对湿度在40%～80%之间变化, 因大西沟地表蒸发大, 其相对湿度略高于冰川.  相似文献   

8.
Basins located in Eastern Turkey are largely fed by snowmelt runoff during spring and early summer seasons. This study investigates the efficiency of artificial neural networks (ANNs) in snowmelt runoff generation. Although ANNs have been used for streamflow simulating/forecasting in the last two decades, using satellite-based snow-covered area (SCA) maps and meteorological observations as inputs to ANN provides a novel basis for estimating streamflow. The proposed methodology is implemented over Upper Euphrates River Basin in Eastern Turkey. SCA data was acquired from Interactive Multisensor Snow and Ice Mapping System (IMS) for an 8-year period from February 2004 to September 2011. Meteorological observations including daily cumulative precipitation and daily average air temperatures were obtained from Turkish State Meteorological Services. The simulation results are promising with coefficient of correlation varying from 0.67 to 0.98 among proposed models. Past days discharge was found to substantially improve the forecast accuracy. The paper presents the expected basin discharge for 2011 water year based on meteorological observations and SCA input.  相似文献   

9.
Obtaining an accurate initial state is recognized as one of the biggest challenges in accurate model prediction of convective events. This work is the first attempt in utilizing the India Meteorological Department (IMD) Doppler radar data in a numerical model for the prediction of mesoscale convective complexes around Chennai and Kolkata. Three strong convective events both over Chennai and Kolkata have been considered for the present study. The simulation experiments have been carried out using fifth-generation Pennsylvania State University-National Center for Atmospheric Research (PSU-NCAR) mesoscale model (MM5) version 3.5.6. The variational data assimilation approach is one of the most promising tools available for directly assimilating the mesoscale observations in order to improve the initial state. The horizontal wind derived from the DWR has been used alongwith other conventional and non-conventional data in the assimilation system. The preliminary results from the three dimensional variational (3DVAR) experiments are encouraging. The simulated rainfall has also been compared with that derived from the Tropical Rainfall Measuring Mission (TRMM) satellite. The encouraging result from this study can be the basis for further investigation of the direct assimilation of radar reflectivity data in 3DVAR system. The present study indicates that Doppler radar data assimilation improves the initial field and enhances the Quantitative Precipitation Forecasting (QPF) skill.  相似文献   

10.
The cloudburst is defined as a heavy downpour at a very high rainfall rate over small spatio-temporal scale. The Indian states of Uttarakhand (30°15′N; 79°15′E) and Himachal Pradesh (32°29′N; 75°10′E) are prone to cloudburst due to its geographical setup. The large-scale monsoon flow along with elevated orography makes cloudburst phenomena frequent a well as severe over the regions. However, cloudburst and the heavy rainfall events occasionally, become difficult to distinguish. The present study attempts to identify the processes associated with cloudburst over elevated orography and compare it with one of the most debated event of 2013 which was reported as heavy rainfall but, not a cloudburst by Indian Meteorological Department (IMD). The temporal variations of rainfall and cloud-top pressure (CTP) are considered to identify the genesis of the event. The vertical developments of the system along with large-scale circulation pattern are estimated in the present study. The result of the study reveals that the mid-tropospheric dry entrainment, low-level temperature inversion and cloud height clearly distinguish the “cloudburst” and “heavy rainfall” events and confirms that the system of 2013 was indeed a heavy rainfall event and not a cloudburst.  相似文献   

11.
Ruppert H 《GeoJournal》1991,25(1):7-12
The ethnic identities of the various population groups in the Sudan are a product of their specific natural and social environments. The migration of these groups to the towns, especially to Greater Khartoum, involves a drastic change of cultural norms and values. However, the capability of change and the subsequent results are strongly conditioned by the specific background of each ethnic group and by the conditions in its area of origin. This is being proved by a comparative study on three ethnic groups in the Sudan: the Nuba, the Zaghawa and the Hadandawa.  相似文献   

12.
Northeast India region is one of the most seismically active areas in the world. Events data for the period 1897–2010, used in this study has been largely compiled from global ISC, NEIC and GCMT databases. Historical seismicity catalogue of Gupta et al (1986) and some events data from the bulletins of India Meteorological Department are also used. Orthogonal regression relations for conversion of body and surface wave magnitudes to M w,HRVD based on events data for the period 1978–2006 have been derived. An Orthogonal Standard Regression (OSR) relationship has also been obtained for scaling of intensity estimates to M w,NEIC using 126 global intensity events with intensity VI or greater during the period 1975–2010.  相似文献   

13.
Since the late 1960's the Rhodesian Meteorological Services, using a network of six seismograph stations in Rhodesia and neighbouring countries, have greatly improved the monitoring resolution of the seismicity of southern Africa. These data together with existing data for the period January 1950–December 1976 have been used in this study to delineate the main seismicity zones, in southern Africa, which are considered to be areas of incipient rifting forming the southern continuation of the East African Rift System. Fault-mechanism studies further indicate that crustal extension within these zones is similar to the sense found further north in East Africa.  相似文献   

14.
地球观测数据卫星分发系统(GEONETCast)借助通信卫星,把从地面站点、航空和航天平台获取的观测数据、产品传送给广大的用户。GEONETCast当前由CMACast,EUMETCast和GEONETCast Americas 3个区域系统组成,作为地球观测组织(GEO)提出的全球综合地球观测系统(GEOSS)的全球地球观测数据和信息卫星分发系统,旨在满足9个社会受益领域的用户需求。GEONETCast建立在现有区域系统之上,利用GEO的协调机制,共同确定GEONETCast系统的整体计划和要求。各区域系统在科研项目和业务建设的支持下,不断发展完善。未来要保障GEONET-Cast健康、良性和可持续的业务运行,还需要加强4个方面的工作:①区域系统之间的互相通信;②保持GEONETCast的开放性和动态性,发展更多的数据提供者提供地球观测数据;③发展更多的数据使用者;④数据政策。  相似文献   

15.
Meteorological data and heat stress indices from 1958 to 2007 in the Three Gorges area were investigated in this study. It is found that there is a (1) mild augmentation of the diurnal temperature range in the region (2) antithetical trends in mean\maximum\minimum temperatures, indicated by warmer winters and slightly cooler summers and (3) declining linear trends of the number of (very) hot days and annual frequencies of (long) heat waves, despite rising frequencies of (very) hot days and annual short heat waves. A U-shape was detected for all the climatic indices, with low values occurring mostly in the 1980s. However, spatial variations exist. Decreasing trends of hot days and frequency of heat waves were more evident in areas like Shapingba, where high annual temperatures were recorded. The finding also suggests a positive impact of the subtropical high on high temperatures and extreme temperature events.  相似文献   

16.
Data capabilities of satellites remote sensor systems are briefly discussed. Monthly remotely sensored data of NIMBUS 3 meteorological satellite over parts of the Sudan, West of Lake Chad in Africa, using the HRIR — High Resolution Infra Red Radiometer (sensing between 0.7–1.3 u wavelength) are used to study the monthly shifts in the vegetation boundaries for this area. These shifts are shown to be caused by changes in soil moisture content which is controlled by the prevailing meteorological conditions in the area during the months.  相似文献   

17.
El Arifi  Salih A. 《GeoJournal》1985,11(4):349-359
Resource management, protection and promotion are very critical issues facing many parts of our rapidly changing world. In most developing countries, such issues are handled by both central and local governments, but quite often specialised government agencies are entrusted with these jobs. In Sudan, and since 1971, local government has become more involved than ever with the issue of natural resources. This research assesses the performance of a single local government unit in Western Sudan with regard to the above mentioned issues. Out of the multiplicity of resources in the council, only natural grazing is selected for the focus of this assessment study, because of its high significance in the local socio-economic set-up. A lengthy field-study was carried out to determine the resource situation and how it affects policy and control and promotion measures. This council has failed; a situation typical of most rural councils in Sudan. Worst of all, the natural grazing is deteriorating rapidly under stocking rates which exceed the carrying capacity by 49%, a fact that has already enhanced desertification.This research is partially sponsored by the UNU.  相似文献   

18.
Monthly rainfalls of the main rainy period (April – October) in Sudan are quantitatively related to atmospheric factors which include vertical atmospheric motion and the depth of maritime SW winds. Other atmospheric properties which are studied in relation to rainfall include the thermal and moisture factors. From these specified factors a logical consideration of cause and effect is made with respect to rainfall over the Sudan as a whole. Multiple regression analysis has been used as a valuable tool in such analysis of causal relationships. It is also a useful technique by which to obtain reasonable estimates of rainfall for areas without rain gauges, and to assess the relative importance of causative factors of the rainfall amounts and spatial variations. Other statistical techniques used for examining the causal analysis are those of simple, partial and multiple correlation coefficients.  相似文献   

19.
The mainly continental deposits of northwest Sudan and south-west Egypt have been correlated with coeval shallow marine and marine deposits in northern Egypt along a north-south running cross-section, based on surface and subsurface data. The palaeodepth curve of northern Egypt illustrates the gradual seal-level rise, reaching its maximum during the Late Cretaceous with conspicuous advances during the Aptian and late Cenomanian. A general highstand is also recorded during the Campanian-Maastrichtian in north-west Sudan. A detailed facies correlation is given for the Aptian and late Cenomanian highstand in western Egypt. The correlation of the Cenomanian Bahariya and Maghrabi formations displays short-term relative sealevel fluctuations. The interpretation illustrates the extensiveness of related erosional processes in the hinterland, partly intensified by temporarily uplift of the Uweinat-Aswan High in the south. Regional uplift and constant erosion took place in south-west Egypt during Coniacian and Santonian times. The regional stratigraphic gaps and uncertain interpretation of the Bahariya Uplift are induced by the influence of the Trans-African Lineament, especially during the Late Cretaceous. Low-stand fluvial sheet sandstones characterized by non-cyclic sequence development and high facies stability occur, especially in the Neocomian and early Turonian. During the Barremian and Albian, fluvial architecture changes to more cyclic fluvial sequences and increasing soil formation, due to increasing subsidence, more humid climatic conditions and the generally rising sea level, culminating in the extensive shallow marine Abu Ballas and Maghrabi formations.  相似文献   

20.
Snail assemblages are used to estimate February and August temperatures during the past 10,000 years in western Europe. We find that a strong warming occurred after the Younger Dryas event, followed by several rapid cooling and warming events. These observations are in agreement with insect and pollen proxy data from the European continent and with estimates of sea-surface temperature from the North Atlantic Ocean as well as with fluctuations of glaciers in western Norway. This study also confirms that terrestrial molluscs can provide reliable climatic data in conjunction with other proxy data.  相似文献   

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