A case study of atmospheric boundary layer features during winter over a tropical inland station — Kharagpur (22.32°N, 87.32°E)   总被引：1，自引：0，他引：1  

Denny P. Alappattu  P. K. Kunhikrishnan  Marina Aloysius  M. Mohan 《Journal of Earth System Science》2009,118(4):281-293

The local weather and air quality over a region are greatly influenced by the atmospheric boundary layer (ABL) structure and dynamics. ABL characteristics were measured using a tethered balloon-sonde system over Kharagpur (22.32°N, 87.32°E, 40m above MSL), India, for the period 7 December 2004 to 30 December 2004, as a part of the Indian Space Research Organization-Geosphere Biosphere Program (ISRO-GBP) Aerosol Land Campaign II. High-resolution data of pressure, temperature, humidity, wind speed and wind direction were archived along with surface layer measurements using an automatic weather station. This paper presents the features of ABL, like ABL depth and nocturnal boundary layer (NBL) depth. The sea surface winds from Quikscat over the oceanic regions near the experiment site were analyzed along with the NCEP/NCAR reanalysis winds over Kharagpur to estimate the convergence of wind, moisture and vorticity to understand the observed variations in wind speed and relative humidity, and also the increased aerosol concentrations. The variation of ventilation coefficient (V C), a factor determining the air pollution potential over a region, is also discussed in detail.  相似文献   

Magnetic anomalies of offshore Krishna-Godavari basin,eastern continental margin of India   总被引：1，自引：0，他引：1  

K. V. Swamy  I. V. Radhakrishna Murthy  K. S. Krishna  K. S. R. Murthy  A. S. Subrahmanyam  M. M. Malleswara Rao 《Journal of Earth System Science》2009,118(4):405-412

The marine magnetic data acquired from offshore Krishna-Godavari (K-G) basin, eastern continental margin of India (ECMI), brought out a prominent NE-SW trending feature, which could be explained by a buried structural high formed by volcanic activity. The magnetic anomaly feature is also associated with a distinct negative gravity anomaly similar to the one associated with 85°E Ridge. The gravity low could be attributed to a flexure at the Moho boundary, which could in turn be filled with the volcanic material. Inversion of the magnetic and gravity anomalies was also carried out to establish the similarity of anomalies of the two geological features (structural high on the margin and the 85°E Ridge) and their interpretations. In both cases, the magnetic anomalies were caused dominantly by the magnetization contrast between the volcanic material and the surrounding oceanic crust, whereas the low gravity anomalies are by the flexures of the order of 3–4 km at Moho boundary beneath them. The analysis suggests that both structural high present in offshore Krishna-Godavari basin and the 85°E Ridge have been emplaced on relatively older oceanic crust by a common volcanic process, but at discrete times, and that several of the gravity lows in the Bay of Bengal can be attributed to flexures on the Moho, each created due to the load of volcanic material.  相似文献   

GPS-TEC variations during low solar activity period (2007–2009) at Indian low latitude stations     

Sanjay Kumar  S. Priyadarshi  S. Gopi Krishna  A. K. Singh 《Astrophysics and Space Science》2012,339(1):165-178

The paper is based on the ionospheric variations in terms of vertical total electron content (VTEC) for the low solar activity period from May 2007 to April 2009 based on the analysis of dual frequency signals from the Global Positioning System (GPS) satellites recorded at ground stations Varanasi (Geographic latitude 25°16′ N, Longitude 82°59′ E), situated near the equatorial ionization anomaly crest and other two International GNSS Service (IGS) stations Hyderabad (Geographic latitude 17°20′ N, longitude 78°30′ E) and Bangalore (Geographic latitude 12°58′ N, longitude 77°33′ E) in India. We describe the diurnal and seasonal variations of total electron content (TEC), and the effects of a space weather related event i.e. a geomagnetic storm on TEC. The mean diurnal variation during different seasons is brought out. It is found that TEC at all the three stations is maximum during equinoctial months (March, April, September and October), and minimum during the winter months (November, December, January and February), while obtaining intermediate values during summer months (May, June, July and August). TEC shows a semi-annual variation. TEC variation during geomagnetic quiet as well as disturbed days of each month and hence for each season from May 2007 to April 2008 at Varanasi is examined and is found to be more during disturbed period compared to that in the quiet period. Monthly, seasonal and annual variability of GPS-TEC has been compared with those derived from International Reference Ionosphere (IRI)-2007 with three different options of topside electron density, NeQuick, IRI01-corr and IRI 2001. A good agreement is found between the GPS-TEC and IRI model TEC at all the three stations.  相似文献   

Seismic loss estimation tool as rapid survey for prioritizing buildings for disaster preparedness: case study to hospital buildings     

Nanda  Radhikesh Prasad  Paul  Nilendu Krishna  Chanu  Ningthoujam Monika 《Natural Hazards》2019,95(3):769-781

Natural Hazards - Hospital buildings must be fully operational after the earthquake to protect the lives of patients as well as to provide emergency care and medical treatment to the victims....  相似文献   

Correction to: Projection of Iron Ore Production     

Mohr  Steve  Giurco  Damien  Yellishetty  Mohan  Ward  James  Mudd  Gavin 《Natural Resources Research》2020,29(1):561-561

Natural Resources Research - The original version of this article unfortunately contained an error in Equation 3.  相似文献   

Low resolution spectroscopy of selected Algol systems     

Shanti Priya Devarapalli  Rukmini Jagirdar  M. Parthasarathy  D. K. Sahu  Vijay Mohan  B. C. Bhatt  Vineet S. Thomas 《Astrophysics and Space Science》2018,363(4):69

The analysis of spectroscopic data for 30 Algol-type binaries is presented. All these systems are short period Algols having primaries with spectral types B and A. Dominant spectral lines were identified for the spectra collected and their equivalent widths were calculated. All the spectra were examined to understand presence of mass transfer, a disk or circumstellar matter and chromospheric emission. We also present first spectroscopic and period study for few Algols and conclude that high resolution spectra within and outside the primary minimum are needed for better understanding of these Algol type close binaries.  相似文献   

Drivers of response to extreme weather warnings among marine fishermen     

Krishna Malakar  Trupti Mishra  Anand Patwardhan 《Climatic change》2018,150(3-4):417-431

Extreme weather events, such as storms and cyclones, pose dire occupational hazards in marine fishing. Thus, warnings against such events can reduce risks to the life and property of fishing communities. This study is an attempt to assess the factors driving fishermen’s decision to respond to weather warnings. Mixed methods, such as exploratory fieldwork, literature review, and focus group discussions, helped in identifying the available weather warnings and hypothesizing the probable factors influencing response to the warnings in the marine fishing community in Maharashtra, India. The plausible drivers of response include perceived potential risk, credibility of the warning and its disseminators, community social capital, and other demographic characteristics. Data from a household survey, comprising 601 fishermen, is used to empirically test the hypotheses. The results suggest that trust in the source and disseminator of the warning is related to higher response rates. There is heterogeneity in the role of community social capital as a motivator to respond. Further, fishermen perceiving traditional information to be more reliable are less likely to respond frequently to the warnings. The findings of the study are relevant for designing interventions which can prompt high response rates to weather warnings from fishermen.  相似文献   

Density and temperature diagnostics of solar emission lines from NeV/MgV and SiVII/MgVII Ions     

Anita Mohan  B. N. Dwivedi  P. K. Raju 《Journal of Astrophysics and Astronomy》1999,20(1-2):51-65

We present NeV/MgV and SiVII/MgVII theoretical line intensity ratios as a function of electron densityN _e and temperatureT _e . These are shown in the form of ratio-ratio diagrams, which should in principle allow bothN _e andT _e to be deduced for the emitting region of the solar plasma. We apply these diagnostics in the solar atmosphere, and discuss the available observations made from space. In most cases, however, we deduceN _e andT _e from the computed absolute line intensities in a spherically symmetric model atmosphere of the Sun. Possible future applications of this investigation to spectral data from the Coronal Diagnostic Spectrometer (CDS) on the Solar and Heliospheric Observatory (SOHO) are briefly discussed.  相似文献   

An Experimental Evidence Of Non-Ducted Propagation During Daytime From The Esd Whistler Observations At Low Latitude Ground Station Jammu     

Lalmani  Babu  Madhu Kaul  Kumar  Rajou  Singh  Rajesh  Singh  Krishna Kumar 《Earth, Moon, and Planets》1999,84(3):151-162

The propagationmechanism of low latitude daytime whistlers is investigated on the basis of ground measurements made continuously during daytime in North India at Jammu (geomag. lat. 22°26°N;L = 1.17). On February 14, 1998 extremely small dispersion (ESD) whistlers with dispersion varying from 5–10 sec^1/2 in surprisingly large numbers were recorded at Jammu during daytime in the late afternoon. The results of a study of the characteristics of ESD whistlers are presented and the discussion indicates that ESD whistlers recorded are the VLF waves radiated from the return stroke of the lightning discharge launched at the ionosphere with different initial wave normal angles, propagated upwards under eitherquasi-longitudinal conditions or pro-longitudinal whistler mode, turned around at different heights due to quasi-transverse propagation and received at Jammu with the dispersion of the order of 5–10 sec^1/2. The validity of this suggestion has been tested by performing actualray-tracing computations in thepresence of equatorial anomaly model. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Laboratory Study of Air Sparging of TCE-Contaminated Saturated Soils and Ground Water   总被引：1，自引：0，他引：1  

Jeffrey A. Adams  Krishna R. Reddy 《Ground Water Monitoring & Remediation》1999,19(3):182-190

Air sparging has proven to be an effective remediation technique for treating saturated soils and ground water contaminated by volatile organic compounds (VOCs). Since little is known about the system variables and mass transfer mechanisms important to air sparging, several researchers have recently performed laboratory investigations to study such issues. This paper presents the results of column experiments performed to investigate the behavior of dense nonaqueous phase liquids (DNAPFs). specifically trichloroethylene (TCE), during air sparging. The specific objectives of the study were (1) to compare the removal of dissolved TCE with the removal of dissolved light nonaqueous phase liquids (LNAPLs). such as benzene or toluene; (2) to determine the effect of injected air-flow rate on dissolved TCE removal; (3) to determine the effect of initial dissolved TCE concentration on removal efficiency; and (4) to determine the differences in removal between dissolved and pure-phase TCE. The test results showed that (1) the removal of dissolved TCE was similar to that of dissolved LNAPL: (2) increased air-injection rates led to increased TCE removal at lower ranges of air injection, but further increases at higher ranges of air injection did not increase the rate of removal, indicating a threshold removal rate had been reached; (3) increased initial concentration of dissolved TCE resulted in similar rates of removal: and (4) the removal of pure-phase TCE was difficult using a low air-injection rate, but higher air-injection rates led to easier removal.  相似文献