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Planetary-Scale Wave Structures of the Earth’s Atmosphere Revealed from the COSMIC Observations 总被引：1，自引：0，他引：1 
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下载免费PDF全文 S. K. A. V. Prasad Rao ANISETTY P. S. BRAHMANANDAM G. UMA A. Narendra BABU HUANG Ching-Yuang G. Anil KUMAR S. Tulasi RAM WANG Hsiao-Lan CHU Yen-Hsyang 《Acta Meteorologica Sinica》2014,28(2):281-295
GPS radio occultation（GPS RO） method,an active satellite-to-satellite remote sensing technique,is capable of producing accurate,all-weather,round the clock,global refractive index,density,pressure,and temperature profiles of the troposphere and stratosphere.This study presents planetary-scale equatorially trapped Kelvin waves in temperature profiles retrieved using COSMIC（Constellation Observing System for Meteorology,Ionosphere,and Climate） satellites during 2006-2009 and their interactions with background atmospheric conditions.It is found that the Kelvin waves are not only associated with wave periods of higher than 10 days（slow Kelvin waves） with higher zonal wave numbers（either 1 or 2）,but also possessing downward phase progression,giving evidence that the source regions of them are located at lower altitudes.A thorough verification of outgoing longwave radiation（OLR） reveals that deep convection activity has developed regularly over the Indonesian region,suggesting that the Kelvin waves are driven by the convective activity.The derived Kelvin waves show enhanced（diminished） tendencies during westward（eastward） phase of the quasi-biennial oscillation（QBO） in zonal winds,implying a mutual relation between both of them.The El Nino and Southern Oscillation（ENSO） below 18 km and the QBO features between 18 and 27km in temperature profiles are observed during May 2006-May 2010 with the help of an adaptive data analysis technique known as Hilbert Huang Transform（HHT）.Further,temperature anomalies computed using COSMIC retrieved temperatures are critically evaluated during different phases of ENSO,which has revealed interesting results and are discussed in light of available literature. 相似文献
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A comparative study on isotopic composition of precipitation in wet tropic and semi-arid stations across southern India 总被引：2，自引：0，他引：2
Isotopic composition of monthly composite precipitation samples from Kozhikode (n = 31), a wet tropic station and Hyderabad (n = 25), a semi-arid station across southern India were studied for a period of four years from 2005 to 2008. During the study
period, the Kozhikode station recorded an average rainfall of 3500 mm while the Hyderabad station showed an average rainfall
of 790 mm. The average stable isotope values in precipitation at the Kozhikode station were δ
18O = −3.52‰, d-excess = 13.72‰; δ
18O = −2.94‰, d-excess = 10.57‰; and δ
18O = −7.53‰, d-excess = 13.79‰, respectively during the pre-monsoon (March–May), monsoon (June–September) and post-monsoon
(October–February) seasons. For the Hyderabad station, the average stable isotope values were δ
18O = −5.88‰, d-excess = 2.34‰; δ
18O = −4.39‰, d-excess = 9.21‰; and δ
18O = −8.69‰, d-excess = 14.29‰, respectively for the three seasons. The precipitation at the two stations showed distinctive
isotopic signatures. The stable isotopic composition of precipitation at the Hyderabad station showed significant variations
from the global trend while the Kozhikode station almost followed the global value. These differences are mainly attributed
to the latitudinal differences of the two stations coupled with the differences in climatic conditions. 相似文献
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Ankeeta AMONKAR Sridhar D. IYER Elapavalooru V.S.S.K. BABU Natarajan SHAILAJHA Areef SARDAR S. MANJU 《《地质学报》英文版》2021,95(5):1591-1603
An insight on occurrence of Fe-rich spherules from the Central Indian Ocean Basin (CIOB) provides an understanding of their distribution at a water depth of >5,000 m. In the present study, Fe-rich spherules are identified to occur in two different sediment types (i.e., siliceous and pelagic) and tectonic settings (i.e. near seamounts and fracture zones). These are single spheres or aggregates, of different sizes (63 to 390 μm) and show textural variability (smooth/quenched, brickwork, corkscrew, interlocking and dendritic). A comparative study based on physical morphology and chemical composition suggests a common mechanism of formation. The association of spherules with fracture zones (FZ) and seamounts signifies that morpho-tectonic features play an important role in fluid-driven hydrovolcanism. Based on the evidence and geologic conditions existing in the basin, we conclude that molten fuel-coolant interaction (MFCI) coupled with submarine hydrothermal exhalations could be an ideal mechanism for the formation of spherules and Fe-particles. The accretion of the spherules on the surface sediments could be a result of recent volcanic phenomena, while those occurring at different depths (280–355, and 460–475 cm-bsf) within the sediment core indicate two different episodes. The study provides a global implication in understanding fluid-driven magmatism in a deep-sea intraplate environment. 相似文献
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Sridhar D. IYER Elapavalooru V.S.S.K. BABU Premchand G. MISLANKAR Anup R. GUJAR Navso V. AMBRE Victor J. LOVESON 《《地质学报》英文版》2010,84(3):515-527
<正>In the present study,we present the occurrence and emplacement of chromite ore deposits from two abandoned mines(Kankavali[Janoli]and Wagda) in the Sindhudurg district of Maharashtra,India.These ores,that occurred as lenses and are associated with metamorphic and ultrabasic rocks,consist of octahedral grains of chromite,while clinochlore is present between the interstices of these grains.The Kankavali(Janoli) and Wagda ores revealed a dominance of Cr_2O_3 followed by FeO and variable proportions of A1_2O_3,MgO,and SiO_2.The former deposits have a slightly higher Cr_2O_3(average 52 wt%) and FeO(～18 wt%) than those from Wagda(Cr_2O_3～50 wt%,FeO～25 wt%).The similar Cr~# values(0.73 for Kankavali[Janoli],0.74 for Wagda) correspond to those reported for typical podiform-type chromite deposits.We suggest that the ores were emplaced as phacoliths in folded outcrops with a steep easterly dip and a northwest-southeast trend.We postulate the continuation of the fold structure from Janoli to Wagda(～4.5 km apart) and the probable (sporadic) occurrence of chromite along this stretch.The possibility of the contribution of chromite grains from these areas to the coastal placer deposits cannot be ruled out. 相似文献
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The occurrence of rhythmic layering of chromite and host serpentinites in the deformed layered igneous complexes has been noticed in the Nuggihalli schist belt (NSB) in the western Dharwar craton, Karnataka, South India. For this study, the chromitite rock samples were collected from Jambur, Tagadur, Bhakatarhalli, Ranganbetta and Byrapur in the NSB. Petrography and ore microscopic studies on chromite show intense cataclasis and alteration to ferritchromite. The ferritchromite compositions are characterized by higher Cr number (Cr/[Cr+Al]) (0.68–0.98) and lower Mg number (Mg/[Mg+Fe]) (0.33–0.82) ratios in ferritchromite compared to that of parent chromite. The formation process for the ferritchromite is thought to be related to the exchange of Mg, Al, Cr, and Fe between the chromite, surrounding silicates (serpentines, chlorites), and fluid during serpentinization. 相似文献
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The Cold Tongue in the South China Sea during Boreal Winter and Its Interaction with the Atmosphere 总被引：2，自引：0，他引：2
A distinct cold tongue has recently been noticed in the South China Sea during the winter monsoon, with the cold tongue temperature minimum occurring in the January or February. This cold tongue shows significant links with the Maritime Continent’s rainfall during the winter period. The cold tongue and its interaction with the Maritime Continent’s weather were studied using Reynolds SST data, wind fields from the NCEP–NCAR reanalysis dataset and the quikSCAT dataset. In addition, rainfall from the GOES Prec... 相似文献
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The marine atmospheric boundary layer (MABL) plays a vital role in the transport of momentum and
heat from the surface of the ocean into the atmosphere. A detailed study on the MABL characteristics was
carried out using high-resolution surface-wind data as measured by the QuikSCAT (Quick scatterometer) satellite.
Spatial variations in the surface wind, frictional velocity, roughness parameter and drag coefficient for the
different seasons were studied. The surface wind was strong during the southwest monsoon season due to the
modulation induced by the Low Level Jetstream. The drag coefficient was larger during this season, due to
the strong winds and was lower during the winter months. The spatial variations in the frictional velocity
over the seas was small during the post-monsoon season (～0.2 m s-1). The maximum spatial variation in the
frictional velocity was found over the south Arabian Sea (0.3 to 0.5 m s-1) during the southwest monsoon period,
followed by the pre-monsoon over the Bay of Bengal (0.1 to 0.25 m s-1). The mean wind-stress curl during the winter
was positive over the equatorial region, with a maximum value of 1.5×10-7N m-3, but on either side of the equatorial belt, a negative wind-stress curl dominated. The area average of the frictional velocity and drag coefficient over the Arabian Sea and Bay of Bengal were also studied. The values of frictional velocity
shows a variability that is similar to the intraseasonal oscillation (ISO) and this was confirmed via wavelet
analysis. In the case of the drag coefficient, the prominent oscillations were ISO and quasi-biweekly mode (QBM).
The interrelationship between the drag coefficient and the frictional velocity with wind speed in both the Arabian
Sea and the Bay of Bengal was also studied. 相似文献
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The decrease of density contrast in sedimentary basins may be approximated by a quadratic function. A sedimentary basin may be viewed as a number of prisms placed in juxtaposition. Equations in closed form for the gravity anomalies of 3D and 2½ D prismatic models are derived. Approximate equations for these models are also derived for rapid calculations. Efficient methods are developed for anomaly calculation by an appropriate use of the exact and approximate equations, and hence, for 3D and 2½ D modelling. The depths to the basement are adjusted iteratively by comparing the calculated anomalies with the observed anomalies. These methods are applied for analysis of the residual anomaly map of the Los Angeles Basin, California. 相似文献