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Search Results: 1 - 10 of 146 matches for " Albedo "
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Negative Feedback in the Polar Ice System  [PDF]
Peter Stallinga, Igor Khmelinskii
Atmospheric and Climate Sciences (ACS) , 2017, DOI: 10.4236/acs.2017.71007
Abstract: One of the ingredients of the anthropogenic global warming hypothesis is the existence of large positive feedback in the climate system. An example is polar ice that, once melted, turns into blacker water that will increase radiation absorption and this rein-forces the melting. This causes a run-away scenario with a point of no return. Here it is shown that the polar ice can also have negative feedback aspects, where a melting of polar ice will cause it to reappear.
Land-Use, Albedo and Air Temperature Changes in the Hula Valley (Israel) during 1946-2008  [PDF]
Moshe Gophen
Open Journal of Modern Hydrology (OJMH) , 2014, DOI: 10.4236/ojmh.2014.44010
Abstract: Long-Term (1946-2008) record of 35,580 measurements of daily mean air temperatures in three meteorological stations (Dan, Dafna, Kfar Blum) in the Hula Valley, within the drainage basin of Lake Kinneret (Israel) was statistically evaluated. Temperature decline after the drainage of the old Lake Hula and adjacent wetlands (1958) and increase from the mid 1980’s, after the implementation of the Hula Project aimed at continuous land green cover were verified. It was suggested that those regional climate changes were due to the change of Albedo levels: lower when land was water covered and higher after regional drainage followed by a decline when vegetation cover became intensive and continuous. Decline of Albedo levels led to higher air temperature and vice versa.
Mapeamento do saldo de radia??o com imagens Landsat 5 e modelo de eleva??o digital
Di Pace, Frederico T.;Silva, Bernardo B. da;Silva, Vicente de P. R. da;Silva, Saulo T. A. da;
Revista Brasileira de Engenharia Agrícola e Ambiental , 2008, DOI: 10.1590/S1415-43662008000400009
Abstract: net radiation is an important component of the surface energy balance in studies of evapotranspiration of irrigated crops and in evaporation of hydrological basins. the objective of this research was to determine the surface radiation balance, by using multispectral imagery of the thematic mapper (landsat 5 satellite). in this study the sebal (surface energy balance algorithm for land) and dem (digital elevation model) were used in order to correct the albedo and vegetation indices under the influence of the slope aspects were used for each study area. tm (thematic mapper) imageries were used for two different dates (december 4, 2000 and october 4, 2001). the calculations were accomplished with and without use of the dem. the land surface temperature and albedo values with dem were larger than without dem in both years, for two selected areas. results also show that for obtaining net radiation based on imagery of the tm - landsat 5 the topographical effects of the study area must be considered.
Impact of Simulated Airborne Soot on Maize Growth and Development  [PDF]
Angela Anda, Berndett Illes
Journal of Environmental Protection (JEP) , 2012, DOI: 10.4236/jep.2012.38092
Abstract: Various effects of the dry deposition of soot on maize were investigated in Keszthely (Hungary) in two consecutive years. In order to be able to study a wider range of weather conditions, some of the plants were placed in a Thornthwaite-Matter type evapotranspirometer and given ad libitum water supplies. Pollution with airborne black carbon was simulated throughout the season by distributing rates of 3 g?m–2 a week using a motorised dust sprayer. Among the plant growth parameters, the leaf area index was increased by 3% - 14%, depending on the year, suggesting that the plants were able to absorb the carbon settling on the leaves. The black carbon reduced the albedo of the canopy by 17.5% - 21.8%, depending on the year, forcing the polluted maize to absorb more energy. Part of this surplus energy was utilised for increased evapotranspiration (3.9% and 11% in the two years) and to raise the surface temperature of the canopy by 1℃ - 2℃ during the mid-day hours. The effect of the contamination on maize was more intense in the hot, dry year. The unfavourable effect of soot on maize fertilisation could be observed as a significant increase in the number of deformed ears, leading to a reduction in grain dry matter. The reduction in dry matter yield for polluted maize grown with irrigation in the evapotranspirometer was far less severe than that on non-irrigated plots, suggesting that irrigation was the most obvious solution for mitigating the negative effects of contamination with airborne soot.
Sea Ice Observations in Polar Regions: Evolution of Technologies in Remote Sensing  [PDF]
Praveen Rao Teleti, Alvarinho J. Luis
International Journal of Geosciences (IJG) , 2013, DOI: 10.4236/ijg.2013.47097
Abstract:

Evolution of remote sensing sensors technologies is presented, with emphasis on its suitability in observing the polar regions. The extent of influence of polar regions on the global climate and vice versa is the spearhead of climate change research. The extensive cover of sea ice has major impacts on the atmosphere, oceans, and terrestrial and marine ecosystems of the polar regions in particular and teleconnection on other processes elsewhere. Sea ice covers vast areas of the polar oceans, ranging from ~18 × 106 km2 to ~23 × 106 km2, combined for the Northern and Southern Hemispheres. However, both polar regions are witnessing contrasting rather contradicting effects of climate change. The Arctic sea ice extent is declining at a rate of 0.53 × 106 km2·decade–1, whereasAntarcticaexhibits a positive trend at the rate of 0.167 × 106 km2·decade–1. This work reviews literature published in the field of sea ice

Environmental Impact Assessment of the Application of Pyrogenic Carbon in Soil  [PDF]
Jorge Laine
Journal of Environmental Protection (JEP) , 2013, DOI: 10.4236/jep.2013.410137
Abstract:

World increasing population and use of energy for transportation and electricity are demanding more extensive and more efficient use of land for agriculture; aiming to both food and biofuel supplies. This communication assesses the possible improvements in soil fertility, capture of greenhouse gas, and rainfall, as a result of the large scale terrestrial application of pyrogenic carbon aiming for desert greening. Fossil hydrocarbon coke is taken into account for this proposal because of the exhaustion of light petroleum proven reserves that is leading to a scenario of abundant coke production from the processing of non-conventional reserves.

Relationship between the Concentration of Impurity and Albedo in Snow Surface  [PDF]
Yuki Komuro, Toshitaka Suzuki
Atmospheric and Climate Sciences (ACS) , 2015, DOI: 10.4236/acs.2015.54034
Abstract: Recent decline of cryosphere typified by retreat of glaciers is often explained by temperature rise due to global warming. However, the existence of glaciers shrinking since before 1950s warming accelerated suggested that decline of cryosphere may be due to not only temperature rise, but also another possibility. As a possible cause of snow and ice melting, it has been pointed out that the surface albedo reduction due to increase of snow impurity, aeolian dust and anthropogenic pollutant, for example. To clarify the quantitative relationship between albedo and impurity in snow surface, we investigated the correlativity of turbidity and metal concentration in snow to the snow surface albedo from the simultaneous observations on the snow-covered area in Yamagata, Japan. The observed albedo shows a tendency of decrease with the turbidity increase in snow surface, we could find strong correlation between the albedo and the turbidity in 76% of contribution factor using logarithmic regression analysis. The relationship of albedo to total concentration of Fe and Al in snow surface shows the similar tendency to turbidity, we could model the relationship using logarithmic equation with high value of contribution ratio, 74% and 66%, respectively. The concentration ratio of Fe/Al is nearly constant with about 0.75, which is close to mean crustal ratio of both elements, therefore, it can be said there is a strong correlation between the albedo and the concentration of mineral particle in snow surface. We cannot find a significant correlation between the albedo and total concentration of Na in snow surface. It can be considered that Na existed as dissolved ion has not significant effect to the albedo in snow surface. These results indicate that the snow albedo correlates strongly with the particulate matter in snow surface, which is typified by mineral particle.
Mapeamento e quantifica??o de parametros biofísicos e radia??o líquida em área de algodoeiro irrigado
Borges, Valéria Peixoto;Oliveira, Aureo Silva de;Silva, Bernardo Barbosa da;
Ciência e Agrotecnologia , 2010, DOI: 10.1590/S1413-70542010000200030
Abstract: remote sensing is currently an important tool for evaluation of net radiation and biophysical parameters over vegetated surfaces on a regional scale. in this research, the sebal - surface energy balance algorithm for land and tm - landsat 5 images were used to map and quantify the albedo (α), ndvi, surface temperature (ts) and net radiation (rn) of center-pivot irrigated cotton fields in the busato farm (13.25o s; 43.42o w; 436 m asl), western of state of bahia, brazil. images from six clear-sky days during the cropping season (january to august 2007) and the corresponding meteorological data were used to run sebal. results showed a clear relationship between α, ndvi, and ts and crop development. the lowest values of α (10 to 20%) and ts (< 24oc), as well as the highest values of ndvi (> 0.75), occurred at the time of maximum ground cover. net radiation decreased progressively with time, following the decrease of the incident solar radiation with increasing solar zenith angle. in the cropped center pivots, rn ranged from 430 wm-2 to 700 wm-2. the remote sensing technique used in this study was consistent in capturing the temporal and spatial variability of the biophysical parameters and net radiation over the irrigated cotton, and their values are in agreement with those reported in the literature for the same crop in irrigated areas.
Photon albedo for water, concrete, and iron at normal incidence, and dependence on the thickness of reflecting material
Markovi? Vladimir M.,Krsti? Dragana,Stevanovi? Nenad,Nikezi? Dragoslav R.
Nuclear Technology and Radiation Protection , 2013, DOI: 10.2298/ntrp1301036m
Abstract: Total number and angular albedo were calculated for commonly used shielding materials, water, concrete, and iron, for photons with initial energies from 10 keV up to 10 MeV and normal incident angle. Influence of material thickness on total number albedo was also investigated. Double differential albedo was determined from simulation of photon transport through materials by using PENELOPE and MCNP software. Backscattered photons were scored and grouped in equal intervals of energy and angle. Analytical expressions for angular and total number albedo as a function of initial energy were obtained. It was shown that angular albedo can be determined with the same formula for three examined materials. Corresponding analytical expressions for number albedo as a function of material thickness were presented in this paper. [Projekat Ministarstva nauke Republike Srbije, br. 171021]
Research of the Reason for Variations of Surface Albedo in Different Areas in China from 1982 to 1998
WANG Ge,HAN Lin,JI Xing-jie
Journal of Chongqing Normal University , 2011,
Abstract: Based on the NOAA-AVHRR data during from 1982 to 1998, we have researched the relations among surface albedo, temperature and precipitation. The results indicated that there was observable difference in the dimensional distribution of mean surface albedo, and the change trends of albedo were not the same in different areas. There were better correlations between surface albedo and temperature & precipitation;there was no lag between surface albedo and temperature & precipitation in northeast of China, the correlation coefficients were 0.732 and 0.631 respectively, but it was lag about one month in Qinghai-Xizang Plateau, the correlation coefficients wer 0.574 and 0.436 respectively, and two months in Huabei Plain, the correlation coefficients were 0.349 and 0.282 respectively. The reason for the increase of annual mean surface albedo in northeast of China was the climate change trends that it became hotter and arider in summer, the precipitation was increased in spring leading to the decrease of the annual mean surface albedo in Huabei Plain, it was because the temperature in cold season was decreased so the annual mean surface albedo was increased.
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