排序方式： 共有60条查询结果，搜索用时 15 毫秒
41.
Global warming can potentially lead to changes in future rainfall and runoff and can significantly impact the regional hydrology and future availability of water resources. All the large‐scale climate impact studies use the future climate projections from global climate models (GCMs) to estimate the impact on future water availability. This paper presents results from a detailed assessment to investigate the capability of 15 GCMs to reproduce the observed historical annual and seasonal mean rainfalls, the observed annual rainfall series and the observed daily rainfall distribution across south‐east Australia. The assessment shows that the GCMs can generally reproduce the spatial patterns of mean seasonal and annual rainfalls. However, there can be considerable differences between the mean rainfalls simulated by the GCMs and the observed rainfall. The results clearly show that none of the GCMs can simulate the actual annual rainfall time series or the trend in the annual rainfall. The GCMs can also generally reproduce the observed daily (ranked) rainfall distribution at the GCM scale. The GCMs are ranked against their abilities to reproduce the observed historical mean annual rainfall and daily rainfall distribution, and, based on the combined score, the better GCMs include MPI‐ECHAM5, MIUB, CCCMA_T47, INMCM, CSIRO‐MK3·0, CNRM, CCCMA_T63 and GFDL 2·0 and those with poorer performances are MRI, IPSL, GISS‐AOM, MIROC‐M, NCAR‐PCM1, IAP and NCAR‐CCSM. However, the reduction in the combined score as we move from the best‐ to the worst‐performing GCMs is gradual, and there is no evident cut‐off point or threshold to remove GCMs from climate impact studies. There is some agreement between the results here and many similar studies comparing the performance of GCMs in Australia, but the results are not always consistent and do significantly disagree with several of the studies. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
42.
Monitoring of deep-sea disturbances, naturai or man-made, has gained significance due to the associated sediment transport and for the ensuing alterations in environmental conditions. During the Indian Deep-sea Environment Experiment (INDEX), resuspension of deep-sea sediment in the Central Indian Basin (CIB) resulted in an increase and lateral movement of suspended particles, vertical mixing of sediments, changes in sedimentological, biochemical, and geochemical conditions and an overall reduction in benthic biomass. Monitoring the conditions 44 months after the experiment has shown a partial recovery of the benthic ecosystem, with indications of restoration and recolonization. 相似文献
43.
Utilizing an eigenfunction decomposition, we study the growth and spectra of energy in the vortical (geostrophic) and wave (ageostrophic) modes of a three-dimensional (3D) rotating stratified fluid as a function of ε = f/N, where f is the Coriolis parameter and N is the Brunt–Vaisala frequency. Throughout, we employ a random large-scale forcing in a unit aspect ratio domain and set these parameters such that the Froude and Rossby numbers are roughly comparable and much less than unity. Working in regimes characterized by moderate Burger numbers, i.e. Bu = 1/ε2 < 1 or Bu ≥ 1, our results indicate profound change in the character of vortical and wave mode interactions with respect to Bu = 1. Indeed, previous analytical work concerning the qualitatively different nature of these interactions has been in limiting conditions of rotation or stratification domination (i.e. when Bu ? 1 or Bu ? 1, respectively). As with the reference state of ε = 1, for ε < 1 the wave mode energy saturates quite quickly and the ensuing forward cascade continues to act as an efficient means of dissipating ageostrophic energy. Further, these saturated spectra steepen as ε decreases: we see a shift from k ?1 to k ?5/3 scaling for k f < k < k d (where k f and k d are the forcing and dissipation scales, respectively). On the other hand, when ε > 1 the wave mode energy never saturates and comes to dominate the total energy in the system. In fact, in a sense the wave modes behave in an asymmetric manner about ε = 1. With regard to the vortical modes, for ε ≤ 1, the signatures of 3D quasigeostrophy are clearly evident. Specifically, we see a k ?3 scaling for k f < k < k d and, in accord with an inverse transfer of energy, the vortical mode energy never saturates but rather increases for all k < k f . In contrast, for ε > 1 and increasing, the vortical modes contain a progressively smaller fraction of the total energy indicating that the 3D quasigeostrophic subsystem, though always present, plays an energetically smaller role in the overall dynamics. Combining the vortical and wave modes, the total energy for k > k f and ε ≤ 1 shows a transition as k increases wherein the vortical modes contain a large portion of the energy at large scales, while the wave modes dominate at smaller scales. There is no such transition when ε > 1 and the wave modes dominate the total energy for all k > k f . 相似文献
44.
Vibrational transition probabilities-namely, Franck-Condon factors and
-centroids-have been evaluated using an approximate analytical method for theD-X system of SiS. Morse potential energy curves forD
1 andX
1+ states of SiS have been constructed using the latest spectroscopic data. The value of
-centroids for the band have been found to decrease linearly with the corresponding wavelength. 相似文献
45.
46.
The present investigation aims to optimize dose and pattern of distillery effluent for sugarcane irrigation. The postmethanated distillery effluent (PMDE) was recorded to have significant amount of micro‐ (Na, Zn, Fe) and macro‐ (Ca, Mg, N‐NO3, P, K, S–SO) nutrients and so was utilized for sugarcane irrigation. Lysimetric studies were conducted to assess the impact of PMDE on sugarcane productivity with different concentrations (50 and 75%) and irrigation patterns (intermittent and pre‐sowing). The intermittent pattern of ferti‐irrigation with 50 and 75% effluent dose for sugarcane crop was found to enhance the growth and quality parameters of crop without impairing the groundwater quality. Results were more pronounced with 75% intermittent irrigation as the percent increase with respect to control for plant length, cane girth, cane weight, number of internodes per cane, dry matter accumulation, juice extraction, sucrose content, and available sugar were 28.0, 42.5, 14.6, 40.2, 54.4, 18.9, 44.9, 57.9, and 50.0%, respectively. It is suggested that PMDE can be used as an alternative of fresh water irrigation and also as a fertilizer for sugarcane, provided that the effluent quality and sugarcane quality is continuously monitored to avoid any contamination. 相似文献
47.
Jai Krishna Pandey Deepa Agarwal Sanjoy Gorain Rajnish Kumar Dubey Manoj Kumar Vishwakarma Kamlesh Kumar Mishra Asim Kumar Pal 《Arabian Journal of Geosciences》2017,10(7):183
This paper presents dust exposure study of 69 workers engaged in 11 categories of jobs over seven coalmines of Jharia Coalfields. Dust samples were analysed for dust concentration, maximum exposure limit (MEL), free silica and other minerals present, and particle size and shape. Study reveals that workers engaged in vicinity of coal/rock cutting operation, are exposed to higher dust concentration (50% samples exceeding MEL), and contain more fine particles (d 50 < 5 μm) with sharp edges. Samples exceeding MEL are classified as high-risk category which needs special attention for taking preventive and protective measure like use of personal protective equipments, job rotation and reduction in dust generation through engineering control using appropriate technology of dust suppression and dust extraction as per their applicability. The study also suggests presence of kaolinite and asbestos along with quartz which make the dust more harmful in nature necessitating further investigation and careful control measures. 相似文献
48.
Sushma Panigrahy Gargi Upadhyay Shibendu Shankar Ray Jai S. Parihar 《Journal of the Indian Society of Remote Sensing》2010,38(4):627-632
The present study has been carried out to delineate the existing cropping systems in the Indo-Gangetic Plains (IGP) using
10 day composite SPOT VEGETATION (VGT) NDVI data acquired over a crop year (June–May). Results showed that it is feasible
to identify the major crops like rice, wheat, sugarcane, potato, and cotton in the dominant growing areas with good accuracy.
Double cropping pattern is the most prevalent. Rice-wheat, sugarcane based, cotton-wheat, rice-potato, rice-rice, maize/millet-wheat
are some of the major rotations followed. Rice-wheat is the dominant rotation accounting for around 40% of the net sown area.
Triple crop rotations was less than 5% of the area and observed in some parts of Uttar Pradesh, Bihar and West Bengal. Single
crop rotation of rice-fallow is significant only in West Bengal. 相似文献
49.
The chemical composition of the global ocean is governed by biological, chemical, and physical processes. These processes interact with each other so that the concentrations of carbon, oxygen, nitrogen (mainly from nitrate, nitrite, ammonium), and phosphorous (mainly from phosphate), vary in constant proportions, referred to as the Redfield ratios. We construct here the generalized total least squares estimator of these ratios. The significance of our approach is twofold; it respects the hydrological characteristics of the studied areas, and it can be applied identically in any area where enough data are available. The tests applied to Atlantic Ocean data highlight a variability of the Redfield ratios, both with geographical location and with depth. This variability emphasizes the importance of local and accurate estimates of Redfield ratios. 相似文献
50.
Impact of Climate Change on Runoff of the Major River Basins of India Using Global Circulation Model (HadCM3) Projected Data 总被引：1，自引：0，他引：1
Praveen K. Gupta Sushma Panigrahy Jai Singh Parihar 《Journal of the Indian Society of Remote Sensing》2011,39(3):337-344
The effects of climate change on hydrological regimes have become a priority area for water and catchment management strategies.
The terrestrial hydrology driven by monsoon rainfall plays a crucial role in shaping the agriculture, surface and ground water
scenario in India. Thus, it is imperative to assess the impact of the changing climatic scenario projected under various climate
change scenario towards the hydrological aspects for India. Runoff is one of the key parameters used as an indicator of hydrological
process. A study was taken up to analyse the climate change impact on the runoff of river basins of India. The global circulation
model output of Hadley centre (HADCM3) projected climate change data was used. Scenario for 2080 (A2 scenario indicating more
industrial growth) was selected. The runoff was modeled using the curve number method in spatial domain using satellite derived
current landuse/cover map. The derived runoff was compared with the runoff using normal climatic data (1951–1980). The results
showed that there is a decline in the future climatic runoff in most of the river basins of India compared to normal climatic
runoff. However, significant reduction was observed for the river basins in the eastern region viz: lower part of Ganga, Bahamani-Baitrani,
Subarnrekha and upper parts of the Mahanadi. The mean projected runoff reduction during monsoon season (June–September) were
18 Billion Cubic Meter (BCM), 3.2 BCM, 3.5 BCM and 5.9 BCM for Brahmaputra-Barak Subarnrekha, Subarnarekha and Brahmini-Baitrani
basin, respectively in comparison to normal climatic runoff. Overall reduction in seasonal runoff was high for Subarnrekha
basin (54.1%). Rainfall to runoff conversion was high for Brahmaputra-Barak basin (72%), whereas coefficient of variation
for runoff was more for Mahanadi basin (1.88) considering the monsoon season. Study indicates that eastern India agriculture
may be affected due to shortage of surface water availability. 相似文献