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1.
Characteristic features of the convectively driven monsoon-trough boundary layer have been explored using the conserved-variable method of analysis. Aerological observations during the Monsoon Trough Boundary Layer Experiment 1990 (MONTBLEX-90) during 18–20 August have been used to investigate the thermodynamic features of the Convective Boundary Layer (CBL). Thermodynamic parameters such as
e
,
es
have been used to study the dynamical aspects of the CBL. Also, mixed-layer heights at an inland station, in the monsoon trough region, obtained from SODAR, are used to document the saturation of the mixed layer after the onset of the monsoon. 相似文献
2.
The thermodynamic structure of the Convective Boundary Layer (CBL) over the Deccan Plateau, India has been investigated using aerological data during the summer monsoon seasons of 1980 and 1981. Conserved-variable analysis and the saturation-point approach, which were used in this study, suggest that the top of the CBL varied between 700–600 mb during the monsoon. The air above the top of the CBL during a weak monsoon was estimated to have subsided for 4 days with a subsidence rate of 30 mb day-1. 相似文献
3.
Analysis of fractures inferred from DBTM and remotely sensed data for groundwater development in godavari sub-watershed, Giridih, Bihar 总被引：2，自引：2，他引：0
Ashok Kumar Savita Tomar Lal Bihari Prasad 《Journal of the Indian Society of Remote Sensing》1999,27(2):105-114
Godavari sub-watershed is a part of buried pediplain developed over ‘Chotanagpur’ granite gneiss. Aquifer is unconfined in nature and groundwater occurs under water table condition. In the study area, groundwater is being exploited only through dugwells which are not capable of sustaining long duration pumping. Groundwater exploration involves the investigation of depth and nature of weathered and fractured horizon. To understand the groundwater storage and retrieval in the area, the basement topography derived from Digital Basement Topography Modelling (DBTM), the lineaments identified on remotely sensed data and geohydrological and physiographic data have been analysed. From DBTM, fracture zones have also been inferred. Lineaments (probable fractures) identified with the help of remotely sensed data are linear features representated on a planner surface. Lineaments in the area are subtle in expression due to deeply buried pediplian. Correlation of lineaments with DBTM reveals that a few lineaments/fractures are deep seated and a few have no sub-surface extensions. Also some sub-surface fractures inferred from DBTM have no expressions on the image. Attempt has been made to delineate more authentic lineaments/fractures with the help of remotely sensed data and DBTM. Correlation of probable fractures inferred from remotely sensed data and fracture zones inferred from DBTM indicated that 40 per cent of lineaments seems to be real fractures. Higher correlation may be achieved where lineaments are prominent and reproducible. It has also been observed that those lineaments which correlate with the fracture zones inferred from DBTM, are also not completely traceable in their linear extent. The exaggeration in length of lineaments may be due to subtle nature of lineaments. Correlation shows that remotely sensed lineaments are improtant for groundwater exploration and its authenticity can be further ascertained with DBTM. 相似文献
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Sumedh K. Humane Savita N. Chaurpagar Samaya S. Humane P. Kundal 《Journal of the Geological Society of India》2010,76(1):75-85
A very rich and diversified dasycladalean algal assemblage has been discovered from the Sylhet Limestone Formation (lower-middle
Eocene) of the Bengal Basin of India for the first time. The depositional environments of the Sylhet Limestone Formation have
been discussed based on the presence of the 11 species of the dasycladalean algae belonging to the three families Dasycladaceae
(Cymopolia inflataramosa Segonzac, C. mayaenese Johnson and Kaska, C. paronai Raineri, Cymopolia sp.), Triploporaceae (Dissocladella lunata Segonzac, Dissocladella sp., Jodotella sloveniaensis Deloffre and Radoicic) and Acetabulariaceae (Clypeina socanensis Deloffre and Radoicic, Clypeina sp., Terquemella sp., Neomeris sp.). The lower Eocene Sylhet Limestone Formation revealed predominance of dasycladalean algal assemblage with the halimedacean
and udoteacean algae and rare occurrence of coralline algae. This suggests their luxuriant growth in the open lagoonal to
shelf environment at the depth of 5–6 m in the warm waters. There is a gradual decrease in the dasycladalean species and genera
in the middle Eocene Sylhet Limestone Formation. The predominance of coralline algae associated with the Sporolithon indicates that the limestone of middle Eocene Sylhet Limestone Formation have been deposited at the littoral to shallow,
high energy open shelf marine environments at a depth of about 40–60 m in warm tropical waters. 相似文献
6.
The thermodynamic structure of the Atmospheric Boundary Layer (ABL) over the Arabian sea region has been studied with the help of 135 aerological observations obtained during MONSOON-77 in the region (10–14° N, 64–68° E) by USSR research vessels. Low-level inversions were observed over the western Arabian sea region (west of 66° E) in association with suppressed convection. The different sublayers of the ABL, viz. the mixed layer, the cloud layer and the inversion/isothermal/stable layer were identified. The low-level stability analysis indicated that in the region east of 66° E, conditions were favourable for deep convection. The thermodynamic transformation of the boundary layer after precipitation was documented. 相似文献
7.
M. Thamban S. S. Naik R. Mohan A. Rajakumar N. Basavaiah Witty D’Souza Sarita Kerkar M. M. Subramaniam M. Sudhakar P. C. Pandey 《Journal of Earth System Science》2005,114(5):443-452
Changes in the terrigenous sediment source and transport mechanisms during the late Quaternary have been investigated using
four sediment cores within the Indian sector of Southern Ocean, using the magnetic susceptibility (MS) and sedimentological
records. Sediments deposited during the Holocene and other interglacial periods were characterised by low MS, low sand content,
reduced ice-rafted detritus (IRD) input and increased illite possibly transported via hydrographic advection from the south.
The glacial intervals are characterised by high MS, high sand content, increased IRD input and reduced illite clays, derived
from both local as well as Antarctic sources. Significant reduction in clay fraction and illite content during glacials suggests
that the erosive and transporting capabilities of the deep and bottom waters could have reduced compared to the interglacial
times. The changes in terrigenous influx to this region were significantly influenced by the rhythmic glacial-interglacial
fluctuations in bottom circulation and the position of the Polar Front. 相似文献
8.
Groundwater assessment has been carried out through hydrogeomorphological and geophysical survey. Remotely sensed data has been used to delineate the hydrogeomorphological units. Each hydrogeomorphological unit has been further sub-divided based on the tone, texture and pattern. These units its have been categorised based on depth of weathering, local geomorphological association, recharge characteristics etc. The top layer resistivity of hydrogeomorphological units has been analysed by electrical resistivity method. Correlation between different sub-units of same hydrogeomorphic unit and top soil resistivity has been attempted. The correlation and integration of resistivity map with geomorphological map were carried out through. ‘GRAM’ Geographic information System, This has helped in better understanding the surface resistivity pattern. These sub divisions have different geohydrological and recharge characteristics. Resistivity zonation map prepared on the basis of limited field data anfd through interpolation/extrapolation can be modified/corrected with the help of information derived from remotely sensed data to obtain more realistic picture. 相似文献
9.
Couldrey Matthew P. Gregory Jonathan M. Boeira Dias Fabio Dobrohotoff Peter Domingues Catia M. Garuba Oluwayemi Griffies Stephen M. Haak Helmuth Hu Aixue Ishii Masayoshi Jungclaus Johann Köhl Armin Marsland Simon J. Ojha Sayantani Saenko Oleg A. Savita Abhishek Shao Andrew Stammer Detlef Suzuki Tatsuo Todd Alexander Zanna Laure 《Climate Dynamics》2021,56(1-2):155-187
Sea levels of different atmosphere–ocean general circulation models (AOGCMs) respond to climate change forcing in different ways, representing a crucial uncertainty in climate change research. We isolate the role of the ocean dynamics in setting the spatial pattern of dynamic sea-level (ζ) change by forcing several AOGCMs with prescribed identical heat, momentum (wind) and freshwater flux perturbations. This method produces a ζ projection spread comparable in magnitude to the spread that results from greenhouse gas forcing, indicating that the differences in ocean model formulation are the cause, rather than diversity in surface flux change. The heat flux change drives most of the global pattern of ζ change, while the momentum and water flux changes cause locally confined features. North Atlantic heat uptake causes large temperature and salinity driven density changes, altering local ocean transport and ζ. The spread between AOGCMs here is caused largely by differences in their regional transport adjustment, which redistributes heat that was already in the ocean prior to perturbation. The geographic details of the ζ change in the North Atlantic are diverse across models, but the underlying dynamic change is similar. In contrast, the heat absorbed by the Southern Ocean does not strongly alter the vertically coherent circulation. The Arctic ζ change is dissimilar across models, owing to differences in passive heat uptake and circulation change. Only the Arctic is strongly affected by nonlinear interactions between the three air-sea flux changes, and these are model specific.
相似文献10.
Thermodynamic structure of the marine atmosphere in the region between 80 and 87‡E along 13‡N over the Bay of Bengal was studied
using 13 high resolution radiosonde profiles from surface-400 hPa collected onboard ORV Sagar Kanya during the period 27th–30th
August, during BOBMEX-99. Saturation point concept, mixing line analysis and conserved variable diagrams have been used to
identify boundary layer characteristics such as air mass movement and stability of the atmosphere. The results showed relatively
dry air near the ocean surface between 1000 and 950 hPa. This feature is confirmed by the conserved tetav structure in this layer. Further, tetav seldom showed any inversions in this region. The tetae and tetaes profiles showed persistent low cloud layers between 900 and 700 hPa. The conserved variable diagrams (tetae-q) showed the existence of double mixing line structures approximately at 950 and 700 hPa levels. 相似文献