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Incoming Solar Radiation (incoming + solar_radiation)
Selected AbstractsSharing natural resources: mountain gorillas and people in the Parc National des Volcans, RwandaAFRICAN JOURNAL OF ECOLOGY, Issue 3 2010Hein Van Gils Abstract The compatibility of natural resource use by people and mountain gorillas (Gorilla beringei beringei) within the Parc National des Volcans was studied. The distribution of gorillas was modelled using a Maximum Entropy algorithm. Biophysical predictor variables were trained with daily GPS locations of gorillas during 2006. Elevation, as a climate surrogate, was the best predictor (58%) of the occurrence of gorillas. The mid-altitudes (2500,3500 m a.s.l.) contained the bulk of the gorilla groups. Incoming solar radiation, as proxy for comfortable nesting sites, was the second best predictor (17%). Vegetation types, as foliage provider, (13%) and slope steepness for providing security (12%) were contributing predictors. The modelled and actual gorilla distributions were together overlaid with people's resource use in the park. Both people and gorillas were congregated in the areas identified as most suitable for gorillas. However, within these areas spatial segregation was found between human natural resource-users and gorillas. Therefore, the number of gorillas is likely to be limited by the human natural resource use within the park. A perimeter fence, the introduction of community-based natural resource management, and a buffer zone are discussed as short-, medium- and long-term mitigation measures. Résumé Nous avons étudié la compatibilité entre l'utilisation des ressources naturelles par les hommes et la présence des gorilles de montagnes (Gorilla beringei beringei) dans le Parc National des Volcans. La distribution des gorilles fut modélisée en utilisant un algorithme d'entropie maximum. En 2006, on a testé des variables de prédicteurs biophysiques, avec localisation quotidienne des gorilles par GPS. L'altitude, substitut du climat, était le meilleur prédicteur (58%) de la présence de gorilles. La plupart des groupes de gorilles se trouvaient à des altitudes moyennes (2 500,3 000 m). Le rayonnement solaire, condition de sites de nidification confortables, étaient le deuxième prédicteur (17%). Les types de végétation, fournisseurs de feuilles (13%) et l'importance des pentes, gage de sécurité (12%) étaient des prédicteurs contributeurs. Les distributions modélisées et réelles des gorilles furent superposées à l'utilisation des ressources du parc par les gens. Les hommes et les gorilles étaient rassemblés dans les zones identifiées comme les plus favorables pour les gorilles. Cependant, dans ces zones, on a trouvé une ségrégation spatiale entre les utilisateurs humains des ressources naturelles et les gorilles. Le nombre de gorilles risque donc d'être limité par l'utilisation humaine des ressources naturelles dans le parc. L'on discute de la pose d'une clôture en périphérie, de l'introduction d'une gestion communautaire des ressources naturelles et de la définition d'une zone tampon comme mesures de mitigation à court, moyen et long terme. [source] Energy budget above a temperate mixed forest in northeastern ChinaHYDROLOGICAL PROCESSES, Issue 18 2007Jiabing Wu Abstract Components of the energy budget were measured continuously above a 300-year-old temperate mixed forest at the Changbaishan site, northeastern China, from 1 January to 31 December 2003, as a part of the ChinaFlux programme. The albedo values above the canopy were lower than most temperate forests, and the values for snow-covered canopy were over 50% higher than for the snow-free canopy. In winter, net radiation Rn was generally less than 5% of the summer value due to high albedo and low incoming solar radiation. The annual mean latent heat LE was 37·5 W m,2, accounting for 52% of Rn. The maximum daily evaporation was about 4·6 mm day,1 in summer. Over the year, the accumulated precipitation was 578 mm; this compares with 493 mm of evapotranspiration, which shows that more than 85% of water was returned to the atmosphere through evapotranspiration. The LE was strongly affected by the transpiration activity and increased quickly as the broadleaved trees began to foliate. The sensible heat H dropped at that time, although Rn increased. Consequently, the seasonal variation in the Bowen ratio , was clearly U-shaped, and the minimum value (0·1) occurred on a sunny day just after rain, when most of the available energy was used for evapotranspiration. Negative , values occurred occasionally in the non-growing season as a result of intensive radiative cooling and the presence of water on the surface. The , was very high (up to 13·0) in snow-covered winter, when evapotranspiration was small due to low surface temperature and available soil water. Vegetation phenology and soil moisture were the key variables controlling the available energy partitioning between H and LE. Energy budget closure averaged better than 86% on a half-hourly basis, with slightly greater closure on a daily basis. The degree of closure showed a dependence on friction velocity u*. Copyright © 2006 John Wiley & Sons, Ltd. [source] Constructing a non-linear relationship between the incoming solar radiation and bright sunshine durationINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 12 2010Khil-Ha Lee Abstract This paper reports the application of a non-linear relationship between the incoming shortwave solar radiation and bright sunshine duration. The newly suggested equation is a modified form of the existing Angstrom equation. Measurements of solar radiation and sunshine radiation from 1997 to 2006 at 21 meteorological stations were used to calibrate and validate the suggested equation. The model parameters required to specify the nature of the relationship between solar radiation and sunshine duration were determined by automatically minimizing the difference between the modelled and measured solar radiation. At the 21 meteorological stations, the absolute error (AE) is in the range of ,0.126,0.158 MJm,2 day,1 for the original Angstrom equation, while it is in the range of ,0.089,0.154 MJm,2 day,1 for the modified equation. The root mean square error (RMSE) is also improved by 7,8% for the modified method. The results show that the newly suggested equation generally provides better performance than the existing Angstrom equation. Copyright © 2009 Royal Meteorological Society [source] A Calibrated, High-Resolution GOES Satellite Solar Insolation Product for a Climatology of Florida Evapotranspiration,JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 6 2009Simon J. Paech Paech, Simon J., John R. Mecikalski, David M. Sumner, Chandra S. Pathak, Quinlong Wu, Shafiqul Islam, and Taiye Sangoyomi, 2009. A Calibrated, High-Resolution GOES Satellite Solar Insolation Product for a Climatology of Florida Evapotranspiration. Journal of the American Water Resources Association (JAWRA) 45(6):1328-1342. Abstract:, Estimates of incoming solar radiation (insolation) from Geostationary Operational Environmental Satellite observations have been produced for the state of Florida over a 10-year period (1995-2004). These insolation estimates were developed into well-calibrated half-hourly and daily integrated solar insolation fields over the state at 2 km resolution, in addition to a 2-week running minimum surface albedo product. Model results of the daily integrated insolation were compared with ground-based pyranometers, and as a result, the entire dataset was calibrated. This calibration was accomplished through a three-step process: (1) comparison with ground-based pyranometer measurements on clear (noncloudy) reference days, (2) correcting for a bias related to cloudiness, and (3) deriving a monthly bias correction factor. Precalibration results indicated good model performance, with a station-averaged model error of 2.2 MJ m,2/day (13%). Calibration reduced errors to 1.7 MJ m,2/day (10%), and also removed temporal-related, seasonal-related, and satellite sensor-related biases. The calibrated insolation dataset will subsequently be used by state of Florida Water Management Districts to produce statewide, 2-km resolution maps of estimated daily reference and potential evapotranspiration for water management-related activities. [source] Effects of fire severity in a north Patagonian subalpine forestJOURNAL OF VEGETATION SCIENCE, Issue 1 2005Thomas Kitzberger Abstract. Question: What is the relative importance of fire-induced canopy mortality, soil burning and post-fire herbivory on tree seedling performance? Location: Subalpine Nothofagus pumilio forests at Challhuaco valley (41°13'S, 71°19'W), Nahuel Huapi National Park, Argentina. Methods: We fenced and transplanted soils of three burning severities along a fire severity gradient produced by a fire in 1996. Over two growing seasons we monitored soil water, direct incoming solar radiation, seedling survival, final seedling total biomass and root/shoot ratio. Additionally, we assessed severity-related changes in soil properties. Results: Incoming radiation (an indicator of the amount of canopy cover left by the fire) was the primary factor influencing spring and summer top soil water availability, first and second-year seedling survival and seedling growth. While seedling survival and soil water content were negatively affected by increased radiation, seedling final biomass was highest in very open microsites. Burned soils showed lower water holding capacity and soil carbon; however these changes did not affect topsoil water, and, contrary to expectation, there was a slight tendency toward higher seedling survival on more heavily burned soils. Herbivory significantly reduced seedling survival, but only under high-radiation conditions. While the effect of radiation on final seedling biomass was not affected by herbivory, R/S ratios were significantly reduced by herbivory in high radiation micro sites. Conclusions: Despite inducing faster aerial growth, increased radiation and herbivory in severely burned sites may effectively prevent post-fire regeneration in north Patagonian subalpine forest where seed sources are not limiting. [source] Meridional energy transport in the coupled atmosphere,ocean system: scaling and numerical experimentsTHE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 644 2009Geoffrey K. Vallis Abstract We explore meridional energy transfer in the coupled atmosphere,ocean system, with a focus on the extratropics. We present various elementary scaling arguments for the partitioning of the energy transfer between atmosphere and ocean, and illustrate those arguments by numerical experimentation. The numerical experiments are designed to explore the effects of changing various properties of the ocean (its size, geometry and diapycnal diffusivity), the atmosphere (its water vapour content) and the forcing of the system (the distribution of incoming solar radiation and the rotation rate of the planet). We find that the energy transport associated with wind-driven ocean gyres is closely coupled to the energy transport of the midlatitude atmosphere so that, for example, the heat transport of both systems scales in approximately the same way with the meridional temperature gradient in midlatitudes. On the other hand, the deep circulation of the ocean is not tightly coupled with the atmosphere and its energy transport varies in a different fashion. Although for present-day conditions the atmosphere transports more energy polewards than does the ocean, we find that a wider or more diffusive ocean is able to transport more energy than the atmosphere. The polewards energy transport of the ocean is smaller in the Southern Hemisphere than in the Northern Hemisphere; this arises because of the effects of a circumpolar channel on the deep overturning circulation. The atmosphere is able to compensate for changes in oceanic heat transport due to changes in diapycnal diffusivity or geometry, but we find that the compensation is not perfect. We also find that the transports of both atmosphere and ocean decrease if the planetary rotation rate increases substantially, indicating that there is no a priori constraint on the total meridional heat transport in the coupled system. Copyright © 2009 Royal Meteorological Society [source] Near-ground solar radiation along the grassland,forest continuum: Tall-tree canopy architecture imposes only muted trends and heterogeneityAUSTRAL ECOLOGY, Issue 1 2010DAVID D. BRESHEARS Abstract Solar radiation directly and indirectly drives a variety of ecosystem processes. Our aim was to evaluate how tree canopy architecture affects near-ground, incoming solar radiation along gradients of increasing tree cover, referred to as the grassland,forest continuum. We evaluated a common type of canopy architecture: tall trees that generally have their lowest level of foliage high above, rather than close to the ground as is often the case for shorter trees. We used hemispherical photographs to estimate near-ground solar radiation using the metric of Direct Site Factor (DSF) on four sites in north Queensland, Australia that formed a grassland,forest continuum with tree canopy cover ranging from 0% to 71%. Three of the four sites had tall Eucalyptus trees with foliage several metres above the ground. We found that: (i) mean DSF exceeded >70% of the potential maximum for all sites, including the site with highest canopy cover; (ii) DSF variance was not highly sensitive to canopy coverage; and (iii) mean DSF for canopy locations beneath trees was not significantly lower than for adjacent intercanopy locations. Simulations that hypothetically placed Australian sites with tall tree canopies at other latitude,longitude locations demonstrated that differences in DSF were mostly due to canopy architecture, not specific site location effects. Our findings suggest that tall trees that have their lowest foliage many metres above the ground and have lower foliar density only weakly affect patterns of near-ground solar radiation along the grassland,forest continuum. This markedly contrasts with the strong effect that shorter trees with foliage near the ground have on near-ground solar radiation patterns along the continuum. This consequence of differential tree canopy architecture will fundamentally affect other ecosystem properties and may explain differential emphases that have been placed on canopy,intercanopy heterogeneity in diverse global ecosystem types that lie within the grassland,forest continuum. [source] | ||||||||||||||||