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91.
The atmospheric correction bands 7 and 8 (765nm and 865nm respectively) of the Indian Remote Sensing Satellite IRS P4-0CM
(Ocean Colour Monitor) can be used for deriving aerosol optical depth (AOD) over the oceans. A retrieval algorithm has been
developed which computes the AOD using band 7 data by treating the ocean surface as a dark background after removing the Rayleigh
path radiance in the sensor-detected radiances. This algorithm has been used to detect marine aerosol distributions at different
coastal and offshore locations around India.
A comparison between OCM derived AOD and the NOAA operational AOD shows a correlation ∼0.92 while that between OCM derived
AOD and the ground-based sun photometer measurements near the coast of Trivandrum shows a correlation of ∼0.90. 相似文献
92.
Environmental constraints have drastically limited options of sustainable developmentand have severely offset many developmental schemes. In this paper, possibilities of acidic depo-sition, as a counter measure of desertification, are analyzed. Seasonal data of ambient sulfur di-oxide, pH of rain water and soil acidity are collected for over an year and analyzed. Arid environ-ment of surrounding areas of Delhi is considered and analyzed. Though ambient sulfur depositionis well below critical level, it might not be truly indicative of plant survival in arid areas. Results maybe useful in arid area afforestation, and polluting industries relocation, which holds tremendouspotential vis-a-vis sustainable development. 相似文献
93.
A method of seismic zonation based on deterministic modeling of rupture plane is presented in this work. This method is based
on the modeling of finite rupture plane along identified lineaments in the region using the semi-empirical technique, of Midorikawa
[(1993) Tectonophysics 218:287–295]. The modeling procedure follows ω2 scaling law, directivity effects, and other strong motion parameters. The technique of zonation is applied for technoeconomically
important NE part of Brahmaputra valley that falls in the seismic gap region of Himalaya. Zonation map prepared for Brahmaputra
valley for earthquakes of magnitude M > 6.0 show that approximately 90,000 km2 area fall in the highly hazardous zone IV, which covers region that can have peak ground accelerations of order more than
250 cm/s2. The zone IV covers the Tezu, Tinsukia, Dibrugarh, Ziro, North Lakhimpur, Itanagar, Sibsagar, Jorhat, Golaghat, Wokha, Senapati,
Imphal, and Kohima regions. The Pasighat, Daring, Basar, and Seppa region belong to zone III with peak ground accelerations
of the order 200–250 cm/s2. The seismic zonation map obtained from deterministic modeling of the rupture is consistent with the historical seismicity
map and it has been found that the epicenter of many moderate and major earthquakes fall in the identified zones. 相似文献
94.
The system of Roche coordinates developed by Kopal to study the problems of stars in close binary systems has been used to study the problems of small oscillations of rotationally distorted stars. 相似文献
95.
Anita Mohan Bhola N. Dwivedi Enrico Landi 《Journal of Astrophysics and Astronomy》2000,21(3-4):407-411
Using spectra obtained from the SUMER (Solar Ultraviolet Measurements of Emitted Radiation) spectrograph on the spacecraft
SOHO (Solar and Heliospheric Observatory), we investigate the height dependence of electron density, temperature and abundance
anomalies in the solar atmosphere. In particular, we present the behaviour of the solar FIP effect (the abundance enhancement
of elements with first ionization potential < 10 eV in the corona with respect to photospheric values) with height
above an active region observed at the solar limb, with emphasis on the so-called transition region lines. 相似文献
96.
Jean Riotte Laurent Ruiz Stéphane Audry Benjamin Baud Jean-Pierre Bedimo Bedimo Laurie Boithias Jean-Jacques Braun Bernard Dupré Jean-Louis Duprey Mikael Faucheux Christelle Lagane Jean-Christophe Marechal Hemanth Moger Mandalagiri Subbarayappa Mohan Kumar Harshad Parate Olivier Ribolzi Emma Rochelle-Newall Buvaneshwari Sriramulu Murari Varma Muddu Sekhar 《水文研究》2021,35(5):e14196
Despite the importance of tropical ecosystems for climate regulation, biodiversity, water and nutrient cycles, only a few Critical Zone Observatories (CZOs) are located in the tropics. Among these, most are in humid climates, while very few data exist for semi-arid and sub-humid climates, due to the difficulty of estimating hydro-geochemical balances in catchments with ephemeral streams. We contribute to fill this gap by presenting a meteorological and hydro-geochemical dataset acquired at the Mule Hole catchment (4.1 km2), a pristine dry deciduous forest located in a biosphere reserve in south India. The dataset consists of time series of variables related to (i) meteorology, including rainfall, air temperature, relative humidity, wind speed and direction, and global radiation, (ii) hydrology, including water level and discharge at the catchment outlet, (iii) hydrogeology, including manual (monthly) and/or automated (from 15 min to hourly) groundwater levels in nine piezometers and (iv) geochemistry, including suspended sediment content in the stream and chemical composition of rainfall (event based), groundwater (monthly sampling) and stream water (storm events, 15 min to hourly frequency with an automatic sampler). The time series extend from 2003 to 2019. Measurement errors are minimized by frequent calibration of sensors and quality checks, both in the field and in the laboratory. Despite these precautions, several data gaps exist, due to occasional access restriction to the site and instrument destruction by wildlife. Results show that large seasonal and interannual variations of climatic conditions were reflected in the large variations of stream flow and groundwater recharge, as well as in water chemical composition. Notably, they reveal a long-term evolution of groundwater storage, suggesting hydrogeological cycles on a decadal scale. This dataset, alone or in combination with other data, has already allowed to better understand water and element cycling in tropical dry forests, and the role of forest diversity on biogeochemical cycles. As tropical ecosystems are underrepresented by Critical Zone Observatories, we expect this data note to be valuable for the global scientific community. 相似文献
97.
We quantify the correlation between earthquakes and use the same to distinguish between relevant causally connected earthquakes.
Our correlation metric is a variation on the one introduced by Baiesi and Paczuski (Phys Rev E 69:066,106, 2004). A network of earthquakes is constructed, which is time-ordered and with links between the more correlated ones. Data pertaining
to the California region has been used in the study. Recurrences to earthquakes are identified employing correlation thresholds
to demarcate the most meaningful ones in each cluster. The distribution of recurrence lengths and recurrence times are analyzed
subsequently to extract information about the complex dynamics. We find that the unimodal feature of recurrence lengths helps
to associate typical rupture lengths with different magnitude earthquakes. The out-degree of the network shows a hub structure
rooted on the large magnitude earthquakes. In-degree distribution is seen to be dependent on the density of events in the
neighborhood. Power laws are also obtained with recurrence time distribution agreeing with the Omori law. 相似文献
98.
Mohan and Saxena's approach of using the averaging technique of Kippenhahn and Thomas in conjunction with Kopal's method of evaluating various parameters on the Roche equipotentials has been used to compute the effects of rotation and tidal distortions on the periods of small adiabatic radial and nonradial modes of oscillations of a series of composite models of stars. In these stars the density decreases slowly in the core from the centre to the interface and then falls of rapidly in the envelope from the interface to the outer surface. 相似文献
99.
The predicted occultation of the star No. 31 (Mink et al., 1981) by Neptune on September 12, 1983 was observed photoelectrically. Four secondary occultations were recorded before the immersion event. 相似文献
100.
A high galactic latitude HI 21 cm-line absorption survey using the GMRT: I. Observations and spectra
Rekhesh Mohan K. S. Dwarakanath G. Srinivasan 《Journal of Astrophysics and Astronomy》2004,25(3-4):143-183
We have used the Giant Meterwave Radio Telescope (GMRT) to measure the Galactic HI 21-cm line absorption towards 102 extragalactic
radio continuum sources, located at high (|b| > 15°) Galactic latitudes. The Declination coverage of the present survey is δ}> - 45°. With a mean rms optical depth of ∼ 0.003, this is the most sensitive Galactic HI 21-cm line absorption survey to
date. To supplement the absorption data, we have extracted the HI 21-cm line emission profiles towards these 102 lines of
sight from the Leiden Dwingeloo Survey of Galactic neutral hydrogen. We have carried out a Gaussian fitting analysis to identify
the discrete absorption and emission components in these profiles. In this paper, we present the spectra and the components.
A subsequent paper will discuss the interpretation of these results. 相似文献