Frequent occurrence of fog in different parts of northern India is common during the winter months of December and January. Low visibility conditions due to fog disrupt normal public life. Visibility conditions heavily affect both surface and air transport. A number of flights are either diverted or cancelled every year during the winter season due to low visibility conditions, experienced at different airports of north India. Thus, fog and visibility forecasts over plains of north India become very important during winter months. This study aims to understand the ability of a NWP model (NCMRWF, Unified Model, NCUM) with a diagnostic visibility scheme to forecast visibility over plains of north India. The present study verifies visibility forecasts obtained from NCUM against the INSAT-3D fog images and visibility observations from the METAR reports of different stations in the plains of north India. The study shows that the visibility forecast obtained from NCUM can provide reasonably good indication of the spatial extent of fog in advance of one day. The fog intensity is also predicted fairly well. The study also verifies the simple diagnostic model for fog which is driven by NWP model forecast of surface relative humidity and wind speed. The performance of NWP model forecast of visibility is found comparable to that from simple fog model driven by NWP forecast of relative humidity and wind speed. 相似文献
This study aims to quantify the landscape spatio-temporal dynamics including Land Use/Land Cover (LULC) changes occurred in a typical Mediterranean ecosystem of high ecological and cultural significance in central Greece covering a period of 9 years (2001–2009). Herein, we examined the synergistic operation among Hyperion hyperspectral satellite imagery with Support Vector Machines, the FRAGSTATS® landscape spatial analysis programme and Principal Component Analysis (PCA) for this purpose. The change analysis showed that notable changes reported in the experimental region during the studied period, particularly for certain LULC classes. The analysis of accuracy indices suggested that all the three classification techniques are performing satisfactorily with overall accuracy of 86.62, 91.67 and 89.26% in years 2001, 2004 and 2009, respectively. Results evidenced the requirement for taking measures to conserve this forest-dominated natural ecosystem from human-induced pressures and/or natural hazards occurred in the area. To our knowledge, this is the first study of its kind, demonstrating the Hyperion capability in quantifying LULC changes with landscape metrics using FRAGSTATS® programme and PCA for understanding the land surface fragmentation characteristics and their changes. The suggested approach is robust and flexible enough to be expanded further to other regions. Findings of this research can be of special importance in the context of the launch of spaceborne hyperspectral sensors that are already planned to be placed in orbit as the NASA’s HyspIRI sensor and EnMAP. 相似文献
Ambient air pollution, particularly in the urban environment of developing countries, has turned out to be a major health risk factor. We explore the compounded impact of age sensitivity, exposure, poverty, co-morbidity, etc., along with composite air pollution in determining morbidity and health burden of people in Lucknow, India. This cross-sectional study is confined to analyse respiratory health status across different socio-economic and geographic locations using n = 140 in-depth questionnaire method. We used mean daily ambient air pollution data of PM10, PM2.5, SO2, and NO2 for the 2008–2018 period. We used the ecological model framework to assess the risk at different hierarchical levels and compounded severity on a spatial scale. We also used Logistic regression model with log odds and odds ratio to analyze the association of risks outcomes with composite air pollution scores calculated using the principal component analysis method. There is a strong association of location-specific respiratory disease prevalence with an overall 32 percent prevalence. The prevalence of ecological model 1 (individual domain) is 4.3 percent, while ecological model 2 (community domain) has the highest prevalence at 32.4 percent. The logistic regression model shows that respiratory disease load is positively associated with age sensitivity (P < .001) and composite pollution level (P < .001). For another model with suffocation as the outcome variable, composite pollution level (P < .001) and exposure (P < .001) are positively associated. Optimum interventions are required at Ecological models 1, 2, and 3 levels for better respiratory health outcomes.
GeoJournal - Sanitation is a multidimensional concept alluding primarily to provision of services for safe disposal of human excreta, provision of clean potable water as well as maintenance of... 相似文献
Natural Hazards - Karakoram mountains range in north-western part of Himalayas is about 500 km in length and hosts some of the world’s highest peaks and longest glaciers. It is... 相似文献
Natural Hazards - In this study, new hybrid artificial neural network (ANN) models were used for predicting the groundwater resource index. The salp swarm algorithm (SSA), particle swarm... 相似文献
Geotechnical and Geological Engineering - Rocks encountered in civil and mining engineering structures are generally intersected by discontinuities. The triaxial strength behaviour of a jointed... 相似文献
The effects of the ocean coast on magnetotelluric (MT) data have been studied and results are described in this article. MT
soundings from various sites along coastal plains of Kachchh were acquired where volcanic rocks overlie Mesozoic sediments
having potential resource prospects. The region of our study lies in the proximity of Gulf of Kachchh and Arabian Sea. This
article describes the effects the presence of a conductive body on the acquired MT data. With the help of synthetic MT modelling
and induction arrows we demonstrate the influence of shallow conductive body on the MT data. The modelling results when compared
to the field observations show that much of the high frequencies are unaffected by the coast, however low frequencies of the
data do seem to be distorted by onshore–offshore resistivity contrasts. The least affect on high frequencies can be attributed
to very shallow water depth as well as to the fact that the onshore–offshore resistivity contrasts are not large enough to
influence the high frequency data badly. The results presented here report for the first time the effect of the coast on the
analysis on MT data from Kachchh. Due to several academic as well as industrial onshore–offshore MT experiments presently
being carried out to explore its hydrocarbon potential, our results have an important bearing on designing and acquisition
of future MT surveys in this region. 相似文献
We are very aware of the importance of the ozone layer, without which life on the Earth would not have evolved in the way it has. Solar storms carry energetic protons into the Earth's upper atmosphere,where they boost production of nitrogen oxides which are known as ozone killers and which ultimately increase ultraviolet(UV) radiations. In the present study, we estimate the effects of solar energetic protons during super storms(Dst index -300 nT) over the total ozone column for the last 32 yr. We select a total of seven super storm events that occurred during solar cycles 22–24(for the last 32 yr) having Dst index -300 nT. To that end, we apply superposed epoch analysis(SEA) to verify the impact of storm events on the quantitative variation of total ozone column and on UV radiations during super storm events.After completing the empirical analysis, we conclude that the ozone column gets depleted significantly(22±6.8%) as proton density increases during super storm events and this decrement in the ozone level is further responsible for a substantial increase(26±11.2%) in peak UV radiation intensities. 相似文献
The fundamental approach for the confirmation of any terrestrial meteorite impact structure is the identification of diagnostic shock metamorphic features, together with the physical and chemical characterization of impactites and target lithologies. However, for many of the approximately 200 confirmed impact structures known on Earth to date, multiple scale‐independent tell‐tale impact signatures have not been recorded. Especially some of the pre‐Paleozoic impact structures reported so far have yielded limited shock diagnostic evidence. The rocks of the Dhala structure in India, a deeply eroded Paleoproterozoic impact structure, exhibit a range of diagnostic shock features, and there is even evidence for traces of the impactor. This study provides a detailed look at shocked samples from the Dhala structure, and the shock metamorphic evidence recorded within them. It also includes a first report of shatter cones that form in the shock pressure range from ~2 to 30 GPa, data on feather features (FFs), crystallographic indexing of planar deformation features, first‐ever electron backscatter diffraction data for ballen quartz, and further analysis of shocked zircon. The discovery of FFs in quartz from a sample of the MCB‐10 drill core (497.50 m depth) provides a comparatively lower estimate of shock pressure (~7–10 GPa), whereas melting of a basement granitoid infers at least 50–60 GPa shock pressure. Thus, the Dhala impactites register a strongly heterogeneous shock pressure distribution between <2 and >60 GPa. The present comprehensive review of impact effects should lay to rest the nonimpact genesis of the Dhala structure proposed by some earlier workers from India. 相似文献