Found 9887 publications. Showing page 119 of 396:
2000
2004
Patterns of CO2 and radiocarbon across high northern latitudes during International Polar Year 2008.
2011
Plants rely on spectral cues present in their surroundings, generated by the constantly changing light environment, to guide their growth and reproduction. Photoreceptors mediate the capture of information by plants from the light environment over a wide range of wavelengths, but despite extensive evidence that plants respond to various light cues, only fragmentary data have been published showing patterns of diurnal, seasonal and geographical variation in the spectral composition of daylight. To illustrate patterns in spectral photon ratios, we measured time series of irradiance spectra at two distinct geographical and climatological locations, Helsinki, Finland and Gual Pahari, India. We investigated the drivers behind variation of the spectral photon ratios measured at these two locations, based on the analysis of over 400 000 recorded spectra. Differences in spectral irradiance were explained by different atmospheric factors identified through multiple regression model analysis and comparison to spectral irradiance at ground level simulated with a radiative transfer model. Local seasonal and diurnal changes in spectral photon ratios were related to solar elevation angle, atmospheric water-vapour content and total ozone column thickness and deviated from their long-term averages to an extent likely to affect plant photobiology. We suggest that future studies should investigate possible effects of varying photon ratios on terrestrial plants. Solar elevation angle especially affects the patterns of B:G and B:R ratios. Water vapour has a large effect on the R:FR photon ratio and modelled climate scenarios predict that increasing global temperatures will result in increased atmospheric water vapour. The development of proxy models, utilising available data from weather and climate models, for relevant photon ratios as a function of solar elevation angle and atmospheric factors would facilitate the interpretation of results from past, present and future field studies of plants and vegetation.
Elsevier
2020
1999
2009
Past and Future Grand Challenges in Marine Ecosystem Ecology
Frontiers Media S.A.
2020
2003
2005
2005
Passive sampling of SO2 and NO2 ambient air concentrations in Cairo. NILU OR
A screening study was undertaken in greater Cairo to check and verify the ambient air pollution monitoring network operated by EIMP/EEAA. The passive samplers were installed in field to measure ground level concentrations in different microenvironments as a result of emissions from traffic and industry. The possibilities for exceeding the EEAA Law no. 4 and the World Health Organisation¿s (WHO) air quality guidelines for SO2 were identified in two areas of Cairo. NO2 concentration limits were high in some selected streets. The passive sampling results compared reasonably well with the permanent network operated by EIMP/EEAA.
2001
2018
2017