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181.
Shivani Shah B. M. Rao Prashant Kumar P. K. Pal 《Journal of Earth System Science》2010,119(6):775-781
Since the beginning of the summer monsoon 2009, experimental mesoscale weather forecasts in real time are being generated
using WRF model by the Meteorology and Oceanography Group at the Space Applications Centre (ISRO) and are disseminated through
MOSDAC () to various users. To begin with, the 12 h, 24 h and 48 h forecasts for the western India region are made available. A study
is undertaken to comprehensively assess the cloudiness prediction performance of WRF model. The evaluations have been made
over the three months period during monsoon 2009. INSAT cloud imagery data has been used as a reference for these evaluations.
The verification strategy includes computation of various skill scores. It is seen that probability of detection (POD) of
cloud is 84% and the false alarm rate (FAR) is around 18%. It is hoped that this assessment will provide information on the
use of these forecasts in various applications. 相似文献
182.
Kaushar Ali Sunil Sonbawane D. M. Chate Devendraa Siingh P. S. P. Rao P. D. Safai K. B. Budhavant 《Journal of Earth System Science》2010,119(6):753-762
Surface snow and lake water samples were collected at different locations around Indian station at Antarctica, Maitri, during December 2004–March 2005 and December 2006–March 2007. Samples were analyzed for major chemical ions. It is found that average pH value of snow is 6.1. Average pH value of lake water with low chemical content is 6.2 and of lake water with high chemical content is 6.5. The Na+ and Cl? are the most abundantly occurring ions at Antarctica. Considerable amount of SO 4 2? is also found in the surface snow and the lake water which is attributed to the oxidation of DMS produced by marine phytoplankton. Neutralization of acidic components of snow is mainly done by NH 4 + and Mg2+. The Mg2+, Ca2+ and K+ are nearly equally effective in neutralizing the acidic components in lake water. The NH 4 + and SO 4 2? occur over the Antarctica region mostly in the form of (NH4)2SO4. 相似文献
183.
A. K. Sharma M. V. Rokade R. Kondala Rao S. Gurubaran P. T. Patil 《Journal of Earth System Science》2010,119(4):461-470
The main aim of the paper is to describe mesosphere and lower thermosphere (MLT) wind field observed between June 2000 and
May 2002 by medium frequency (MF) radars at two locations near the equatorial region and at tropical latitude. We have presented
and compared observations of mean horizontal winds in the mesosphere and lower thermosphere (MLT) region over Kolhapur (16.8°N,
74.2°E) and Tirunelveli (8.7°N, 77.8°E). Our analysis reveals annual oscillation in the zonal wind and semi-annual oscillation
in the meridional wind over Kolhapur. On the other hand, results over Tirunelveli reveal semi-annual oscillation (SAO) in
the zonal wind and annual oscillation in the meridional wind. Also we have observed enhanced magnitude of wind speed in spring
equinox period of 2002 exhibiting the signatures of the quasi-biennial oscillation (QBO) over Tirunelveli. 相似文献
184.
The Nature and Distribution of Particulate Matter in the Mandovi Estuary,Central West Coast of India
Pratima Mohan Kessarkar Venigalla Purnachandra Rao Ranjan Shynu Prakash Mehra Blossom E. Viegas 《Estuaries and Coasts》2010,33(1):30-44
Systematic seasonal variations of suspended particulate matter (SPM) along a 44-km transect of the Mandovi estuary reveal
that the concentrations of SPM are low at river-end stations, increase generally seaward, and are highest at sea-end stations
of the estuary. An estuarine turbidity maximum (ETM) occurs at sea-end stations during June–September when river discharge
is high and also in February–May when river discharge is low. These are the two windiest times of year, the former associated
with the southwest monsoon and the latter characterized by a persistent sea breeze. The salinity vs. SPM plot shows that high
SPM is a seaward deposit and skewed landward. Suspended matter comprised of floccules, fecal pellets, and aggregates that
consist of clay and biogenic particles occur everywhere in the estuary. Diatoms are the most common and are of marine type
at the sea-end and freshwater-dominated at river-end stations of the estuary. SPM is characterized by kaolinite- and smectite-rich
clay mineral suites at the river- and sea-end stations, respectively. Smectite concentrations increase seawards with the increase
in SPM content and are not influenced by salinity. Wind-driven waves and currents and biogeochemical processes at the mouth
of estuary likely play an important role in the formation of ETM in resuspension and transformation of SPM into floccules
and aggregates and in their upkeep or removal. 相似文献
185.
Geochemistry of fluoride rich groundwater in Kolar and Tumkur Districts of Karnataka 总被引:2,自引:2,他引:0
Groundwater is a significant water resource in India for domestic, irrigation, and industrial needs. By far the most serious
natural groundwater-quality problem in India, in terms of public health, derives from high fluoride, arsenic, and iron concentrations.
Hydrogeochemical investigation of fluoride contaminated groundwater samples from Kolar and Tumkur Districts in Karnataka are
undertaken to understand the quality and potability of groundwater from the study area, the level of fluoride contamination,
the origin and geochemical mechanisms driving the fluoride enrichment. Majority of the groundwater samples did not meet the
potable water criteria as they contained excess (>1.5 mg/L) fluoride, dissolved salts (>500 mg/L) and total hardness (75–924 mg/L).
Hydrogeochemical facies of the groundwater samples suggest that rock weathering and evaporation–crystallization control the
groundwater composition in the study area with 50–67% of samples belonging to the Ca–HCO3 type and the remaining falling into the mixed Ca–Na–HCO3 or Ca–Mg–Cl type. The saturation index values indicated that the groundwater in the study area is oversaturated with respect
to calcite and under-saturated with respect to fluorite. The deficiency of calcium ion concentration in the groundwater from
calcite precipitation favors fluorite dissolution leading to excess fluoride concentration. 相似文献
186.
S. Sankaran R. Rangarajan K. Krishna Kumar S. Saheb Rao Smita Vishwasrao Humbarde 《Environmental Earth Sciences》2010,60(4):757-764
A chemical factory near Ranipet town in Vellore district, in the state of Tamil Nadu, India produced chromium-based inorganic
chemicals. The factory area in granite gnessic terrain receives an average annual rainfall of 1,000 mm. About 1.5 lakh tons
of solid wastes rich in hexavalent chromium (Cr6+), spreading over an area of 14,000 m2 (about 3.5 acres), having about 4 m thickness, is accumulated in an open yard within the factory premises. The soil and groundwater
in and around the factory area are contaminated with Cr6+ leached from dump site. Cr6+ is carcinogenic in nature and when leached in water can lead to respiratory disorders. Resistivity surveys comprising vertical
electrical sounding, multielectrode resistivity imaging, drilling of bore wells, chemical analysis of soil, formation and
groundwater samples and bore hole tracer studies were carried out within the factory and adjoining areas to decipher subsurface
geology, hydraulic behavior of dyke as natural barrier and lateral and vertical extent of pollution zone in and around the
chromium dump site. The data obtained were integrated and interpreted for understanding the pollution migration and its impact
on environment. Remedial measures are suggested for containing the contamination. 相似文献
187.
Raja Sengupta Griet Vankeerberghen Ruoxuan Wen Jing Rao Yanbing Chen 《Transactions in GIS》2023,27(4):1090-1103
GIS-enabled historiography allows us to shed light on missing or poorly understood aspects of historical events. Here, we use agent-based models (ABMs), least cost path analysis (LCPA), and space–time paths to recreate and evaluate possible modes and routes of travel undertaken by Shi Rao, a Western Han official. A diary was found in Shi Rao's tomb that includes information about his travels over 1 year (11 BCE), including start and end times of his journeys. But it leaves out details regarding modes of transport or exact routes. Using Tan Qixiang's historical atlas, we digitized river networks and utilized modern topographic data to digitally recreate the landscape as it was during Shi Rao's travels. This was then used to evaluate possible journeys via rivers (using ABMs) and roads (using LCPA), and compared to historical speed of boats, carts and horses, with findings indicating that horseback may have been the viable option. 相似文献
188.
A. Sandeep T. Narayana Rao C. N. Ramkiran S. V. B. Rao 《Boundary-Layer Meteorology》2014,153(2):217-236
The differences and similarities in atmospheric boundary-layer (ABL) characteristics, in particular the ABL height, evolution and wind field, between two contrasting episodes of the Indian summer monsoon have been studied using measurements from wind profilers and an instrumented 50-m tower at Gadanki in India. The observed differences are discussed in light of various forcing mechanisms, in particular the effect of soil moisture on the surface energy balance and ABL. The differences in ABL height, its evolution and the wind field between episodes are quite pronounced. Wet episodes not only have a shallower ABL but also the growth is delayed by 1–4 h when compared with that for dry episodes. Abundant soil moisture during the wet episodes (a factor of two greater than during the dry episodes) reduces the buoyancy flux, and thereby not only limits the ABL height but also delays the commencement of ABL growth. The low-level jet (LLJ) is stronger during the dry episodes and has a larger diurnal range than during the wet episodes. The highest occurrence and magnitude of LLJ apparent at a height of 1.5 km during early morning hours shift progressively with height and time till the afternoon, following ABL evolution. The weaker LLJ during the wet episodes is attributed to its southward migration from its mean position (15 \(^{\circ }\) N). Larger signal-to-noise ratio and spectral width values are observed during the early night to midnight, compared to noon-time, when the ABL is buoyantly turbulent. 相似文献
189.
Hua Li Benqiang Rao Gaohong Wang Si Shen Dunhai Li Chunxiang Hu Yongding Liu 《Environmental Earth Sciences》2014,71(1):245-253
Artificial biological soil crusts (ABSCs), formed by inoculating Microcoleus vaginatus Gom. and Scytonema javanicum Born. et Flah. onto the topsoil of desert dunes, proved to be effective tools for the stabilization of moving dunes and promotion of soil fertility. As dominant driving forces in arid habitats, the abiotic environmental conditions of undulating dunes produce a gradient of abiotic stresses on cyanobacteria. Cyanobacteria are considered pioneering phototrophs in early soil crust communities in deserts. In this study, the development of ABSCs under various environmental site conditions was investigated using 16S rRNA-based polymerase chain reaction, denaturing gradient gel electrophoresis (DGGE), and soil property measurements. After inoculation in 2002 and long-term development, patchy moss crusts were observed on the dunes. All of the available sequenced bands in the DGGE gels belonged to Oscillatoriales and Nostocales. The dominant Nostocales genus in the ABSCs was still Scytonema; however, more Oscillatoriales genera were identified, which belonged to Microcoleus and Phormidium. The cyanobacterial compositions of different slope types were significantly distinct (p < 0.05), particularly those from windward slopes. The crusts of the top-dune slopes were more heterogeneous. In addition, the soil physicochemical properties and richness indices of the windward slopes were significantly lower than those of the leeward and interdune slopes (p < 0.05). Compared with uninoculated control dunes, all of the inoculated dunes had far higher biodiversities. 相似文献
190.
Prabhakara Prasad P. Satish Kumar K. Seshunarayana T. Rama Rao Ch. 《Arabian Journal of Geosciences》2014,7(7):2633-2639
Randomly distributed ground magnetic data sets, collected along parallel and closely spaced profiles, in small blocks, the blocks being separated/distributed widely over a large area, become, sometimes, unamenable for deriving a meaningful geological model. In such a situation, an approach of “Cumulative Total Intensity Magnetic Anomaly Field (CTIMAF)” has been devised to interpret the sparsely distributed magnetic data sets. A case history has been presented from the lead–zinc mineralized provenance of Ajabgarh Formation of Delhi Fold Belt in the northern part of Ajmer Town. Log-normalized radially averaged power spectrum was computed for the Cumulative Total Intensity Magnetic Anomaly data and depth to the basement is derived. The computed depth of 4.5 km is in good agreement with the Deep Seismic Studies. 相似文献