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1.
A sea-breeze event in south-west Western Australia is simulated using the Regional Atmospheric Modelling System (RAMS) version
6.0. The model is evaluated against high resolution soundings as well as station observations and is shown to reproduce the
qualitative features of the sea breeze well. Sensitivity tests are carried out to investigate the effects of historical land-cover
change and changes in soil moisture on the dynamics of the sea breeze. It is found that land-cover change alone, i.e., a change
from wooded grasslands to bare soil, with no change in soil moisture initialisation, does not significantly alter the overall
structure of the sea breeze but results in higher surface winds due to the reduced vegetation roughness length, which leads
to enhanced surface moisture advection inland. On the other hand, land-cover change in conjunction with increased soil moisture
results in a considerably weaker, shallower, and less penetrative sea breeze, and delays its onset and duration. A sea-breeze
scaling analysis highlights the impact of increasing soil moisture on reducing the sea-breeze volume flux scale. 相似文献
2.
Jatin Srivastava Dinesh Shukla Vishal Chand Ram Naraian Harish Chandra Anant R. Nautiyal 《洁净——土壤、空气、水》2010,38(8):771-774
The presence of arsenic (As) in water is of great public concern. Arsenic exists in three common valence states viz., As(0) metalloid arsenic, As(III) (arsenite) and As(V) (arsenate). Arsenite [As(III)] is the most toxic form among arsenicals which, predominates in anaerobic conditions, generally in flooded soils and in the water with high BOD. Experiments were conducted to investigate the effect of As(III) on the mycorrhization in vetiver (Vetiveria zizanioides (L.) Nash) grass in hydroponics. Studies showed significant alteration in the mycorrhizal colonization in the roots of vetiver exposed to higher concentrations of As(III) starting from 1.0, 2.0, 3.0, 4.0 to 5.0 mg/L prepared in 5% Hoagland nutrient solution without addition of phosphate ions. Considerable reduction in the mycorrhizal intensity (M) was observed in all the treatment sets as compared to the control suggesting a negative impact of the As(III) on the mycorrhizal association. Simultaneously, the study also showed that, As(III) is toxic to the vetiver plants having mycorrhizal association however plants with non‐mycorrhizal (cleansed) roots were found to be able to survive for a longer period exposed to As(III). 相似文献
3.
The south-west of Western Australia has experienced significant land-cover change as well as a decline in rainfall. Given
that most precipitation in the region results from frontal passages, the impact of land-cover change on the dynamics of cold
fronts is explored using the Regional Atmospheric Modeling System version 6.0. Frontal simulations are evaluated against high
resolution atmospheric soundings, station observations, and gridded rainfall analyses and shown to reproduce the qualitative
features of cold fronts. Land-cover change results in a decrease in total frontal precipitation through a decrease in boundary-layer
turbulent kinetic energy and vertically integrated moisture convergence, and an increase in wind speed within the lower boundary
layer. Such processes contribute to reduced convective rainfall under current vegetation cover. 相似文献
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The concept of SOM was originated by Colvocoresses, which was mathematically developed and later modified by Snyder. It is most suitable for continuous mapping of satellite imagery, true to scale along ground track. Simplified mathematical formulation without complicated integral equations and constants of SOM projection for Landsat, SPOT and IRS satellites on Clarke and Everest spheroids are presented in this paper for ease of calculations. 相似文献
6.
Dyutiman Choudhary Bishnu H. Pandit S. P. Kala N. P. Todaria S. Dasgupta Michael Kollmair 《社会与自然资源》2014,27(10):1057-1073
This article highlights the results of an action research to upgrade mountain farmers of bay leaf (Cinnamomum tamala Nees and Eberm) in Udayapur district of Nepal. Farmers received low prices, lacked market information, capacities, and institutional mechanisms, and were exploited by traders. To address these constraints, three independent but interlinked pro-poor value chain (VC) upgrading strategies comprising VC coordination upgrading and horizontal and vertical contractualization were implemented. Information was collected from focus-group discussions with collectors, traders, and facilitators, and a questionnaire was used to collect pre- and postintervention data (n = 120). VC upgrading strategies improved harvesting practices, increased farmers’ bargaining power, and led to a threefold increase in price, which increased household incomes. Results demonstrated improved terms of participation of farmers and a general increase in market price of bay leaf in Udayapur. The study approach can be up scaled to reduce poverty from high value products. 相似文献
7.
Stutee Gupta Arijit Roy Dhruval Bhavsar Rajkanti Kala Sarnam Singh A. Senthil Kumar 《Journal of the Indian Society of Remote Sensing》2018,46(6):945-955
The hills of Uttarakhand witness forest fire every year during the summer season and the number of these fire events is reported to have increased due to increased anthropogenic disturbances as well as changes in climate. These fires cause significant damage to the natural resources which can be mapped and monitored using satellite images by virtue of its synoptic coverage of the landscape and near real time monitoring. This study presents burnt area assessment caused by the fire episode of April 2016 to the forest vegetation. Digital classification of satellite images was done to extract the burnt area which was found to be 3774.14 km2, representing 15.28% of the total forest area of the state. It also gives an account of cumulative progression of forest fire in Uttarakhand using satellite images of three dates viz. 23rd, 27th May and 2nd June, 2016. Results were analyzed at district, administrative and forest division level using overlay analysis. Separate area statistics were given for different categories of biological richness, forest types and protected areas affected by forest fire. The burnt area assessment can be used in mitigation planning to prevent drastic ecological impacts of the forest fire on the landscape. 相似文献
8.
S. S. De Suman Paul S. Barui P. Hazra D. Kala D. K. Haldar A. Ghosh G. Guha 《Earth, Moon, and Planets》2013,111(1-2):79-87
The effect of solar eclipse of July 22, 2009, obscuring up to 91 %, upon the value of point discharge current (PDC) has been reported in this paper. The observation had been taken from Kolkata (Lat. 22.56°N, Long. 88.5°E). During the eclipse period, significant variations in the magnitude of PDC were observed than their average value for the same period in other days. The average value of the PDC for the successive ±10 days adjacent to the solar eclipse day was about 2.253 A.U. (Arbitrary Unit), while the minimum value showed about 2.242 A.U. at the time of greatest phase at 06:26.4 IST (Indian Standard Time). The results are mainly interpreted in terms of changes of the conductivity of the medium during the solar eclipse. 相似文献
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Jatin Rathod Girija Rajaram Radharani Alyana A. Chandrasekhar Reddy D. S. Misra C. G. Patil M. Y. S. Prasad A. G. Ananth 《Journal of Astrophysics and Astronomy》2008,29(1-2):293-302
In the present study, we investigate the possible relationship of IP parameters of solar wind and interplanetary magnetic field with ground-based geomagnetic indices. To carry out the study, we take all the IP shock events listed by Proton Monitor onboard Solar and Heliospheric Observatory (SOHO) during 2005, and plot the time variations of all the IP parameters and geomagnetic parameters (±5 days), centered at the shock arrival time. Next, we obtain scatter plots of absolute values of solar wind parameters such as Vsw, Nsw and Interplanetary Magnetic Field (IMF) components Bx, By, Bz and total B with the values of geomagnetic parameters such as Dst, Kp indices, dayside Magnetopause (MP) distance and Cosmic-Ray Neutron Monitor count (CRNM). The scatter plots show that before the IP shock, the pattern is random with no clear relationship. Following the shock, a clear pattern emerges with a type of relationship being seen — clear for SHARP shocks and less clear for DIFFUSE shocks. A total of 10 shock events for 2005 have been studied. Typical examples of this behaviour are the shock events of January 21, 2005 and May 15, 2005. Our study suggests a definite correlation between changes in the solar wind and interplanetary magnetic field parameters and ground-based geomagnetic response. We are trying to obtain quantitative relationships between these for shock events of 2005. 相似文献