The impact of ultraviolet radiation on the vertical distribution of zooplankton of the genus Daphnia

Nature ◽  
2001 ◽  
Vol 412 (6842) ◽  
pp. 69-72 ◽  
Author(s):  
Stephan C. Rhode ◽  
Markus Pawlowski ◽  
Ralph Tollrian
Keyword(s):  
Ultraviolet Radiation ◽  
Vertical Distribution ◽  
The Impact ◽  
The Vertical Distribution

scholarly journals Multi-model study of mercury dispersion in the atmosphere: Vertical distribution of mercury species

2016 ◽  
Author(s):  
Johannes Bieser ◽  
Franz Slemr ◽  
Jesse Ambrose ◽  
Carl Brenninkmeijer ◽  
Steve Brooks ◽  
...  
Keyword(s):  
Vertical Distribution ◽  
Atmospheric Chemistry ◽  
Lower Troposphere ◽  
Elemental Mercury ◽  
Mercury Species ◽  
Substantial Impact ◽  
Model Studies ◽  
Model Study ◽  
The Impact ◽  
The Vertical Distribution

Abstract. Atmospheric chemistry and transport of mercury play a key role in the global mercury cycle. However, there are still considerable knowledge gaps concerning the fate of mercury in the atmosphere. This is the second part of a model inter-comparison study investigating the impact of atmospheric chemistry and emissions on mercury in the atmosphere. While the first study focused on ground based observations of mercury concentration and deposition, here we investigate the vertical distribution and speciation of mercury from the planetary boundary layer to the lower stratosphere. So far, there have been few model studies investigating the vertical distribution of mercury, mostly focusing on single aircraft campaigns. Here, we present a first comprehensive analysis based on various aircraft observations in Europe, North America, and on inter-continental flights. The investigated models proved to be able to reproduce the distribution of total and elemental mercury concentrations in the troposphere including inter-hemispheric trends. One key aspect of the study is the investigation of mercury oxidation in the troposphere. We found that different chemistry schemes were better at reproducing observed oxidized mercury (RM) patterns depending on altitude. High RM concentrations in the upper troposphere could be reproduced with oxidation by bromine while elevated concentrations in the lower troposphere were better reproduced by OH and ozone chemistry. However, the results were not always conclusive as the physical and chemical parametrizations in the chemistry transport models also proved to have a substantial impact on model results.

scholarly journals Vertical Distribution of Particulates within the Near-Surface Layer of Dry Bulk Port and Influence Mechanism: A Case Study in China

2019 ◽  
Vol 11 (24) ◽  
pp. 7135 ◽  
Author(s):  
Jinxing Shen ◽  
Xuejun Feng ◽  
Kai Zhuang ◽  
Tong Lin ◽  
Yan Zhang ◽  
...  
Keyword(s):  
Vertical Distribution ◽  
Weather Conditions ◽  
Dust Suppression ◽  
Near Surface ◽  
Cargo Handling ◽  
Port Operation ◽  
Pm10 And Pm2.5 ◽  
The Impact ◽  
The Vertical Distribution ◽  
Porous Fence

Knowing the vertical distribution of ambient particulate matter (PM) will help port authorities choose the optimal dust-suppression measures to reduce PM concentrations. In this study, we used an unmanned aerial vehicle (UAV) to assess the vertical distribution (0–120 m altitude) of PM in a dry bulk port along the Yangtze River, China. Total suspended particulates (TSP), PM10, and PM2.5 concentrations at different altitudes were measured at seven sites representing different cargo-handling sites and a background site. Variations in results across sites make it not suitable to characterize the vertical distribution of PM concentration at this port using simple representative distributions. Bulk cargo particle size, fog cannon use, and porous fence all affected the vertical distribution of TSP concentrations but had only minor impacts on PM10 and PM2.5 concentrations. Optimizing porous fence layout according to weather conditions and cargo demand at port have the most potential for mitigating PM pollution related to port operation. As ground-based stations cannot fully measure vertical PM distributions, our methods and results represent an advance in assessing the impact of port activities on air quality and can be used to determine optimal dust-suppression measures for dry bulk ports.

scholarly journals Seasonal cycle of desert aerosols in western Africa: analysis of the coastal transition with passive and active sensors

2017 ◽  
Vol 17 (13) ◽  
pp. 8395-8410 ◽  
Author(s):  
Habib Senghor ◽  
Éric Machu ◽  
Frédéric Hourdin ◽  
Amadou Thierno Gaye
Keyword(s):  
Vertical Distribution ◽  
Satellite Observations ◽  
Boreal Summer ◽  
Wide Field ◽  
Aerosol Layer ◽  
Good Representation ◽  
Mineral Aerosols ◽  
Western Africa ◽  
The Impact ◽  
The Vertical Distribution

Abstract. The impact of desert aerosols on climate, atmospheric processes, and the environment is still debated in the scientific community. The extent of their influence remains to be determined and particularly requires a better understanding of the variability of their distribution. In this work, we studied the variability of these aerosols in western Africa using different types of satellite observations. SeaWiFS (Sea-Viewing Wide Field-of-View Sensor) and OMI (Ozone Monitoring Instrument) data have been used to characterize the spatial distribution of mineral aerosols from their optical and physical properties over the period 2005–2010. In particular, we focused on the variability of the transition between continental western African and the eastern Atlantic Ocean. Data provided by the lidar scrolling CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) onboard the satellite CALIPSO (Cloud Aerosol Lidar and Infrared Pathfinder Satellite Observations) for the period 2007–2013 were then used to assess the seasonal variability of the vertical distribution of desert aerosols. We first obtained a good representation of aerosol optical depth (AOD) and single-scattering albedo (SSA) from the satellites SeaWiFS and OMI, respectively, in comparison with AERONET estimates, both above the continent and the ocean. Dust occurrence frequency is higher in spring and boreal summer. In spring, the highest occurrences are located between the surface and 3 km above sea level, while in summer the highest occurrences are between 2 and 5 km altitude. The vertical distribution given by CALIOP also highlights an abrupt change at the coast from spring to fall with a layer of desert aerosols confined in an atmospheric layer uplifted from the surface of the ocean. This uplift of the aerosol layer above the ocean contrasts with the winter season during which mineral aerosols are confined in the atmospheric boundary layer. Radiosondes at Dakar Weather Station (17.5° W, 14.74° N) provide basic thermodynamic variables which partially give a causal relationship between the layering of the atmospheric circulation over western Africa and their aerosol contents throughout the year. A SSA increase is observed in winter and spring at the transition between the continent and the ocean. The analysis of mean NCEP (National Centers for Environmental Prediction) winds at 925 hPa between 2000 and 2012 suggest a significant contribution of coastal sand sources from Mauritania in winter which would increase SSA over the ocean.

scholarly journals Shrub type dominates the vertical distribution of leaf C : N : P stoichiometry across an extensive altitudinal gradient

2017 ◽  
Author(s):  
Wenqiang Zhao ◽  
Peter B. Reich ◽  
Qiannan Yu ◽  
Ning Zhao ◽  
Chunying Yin ◽  
...  
Keyword(s):  
Vertical Distribution ◽  
Altitudinal Gradient ◽  
Environmental Changes ◽  
Interactive Effects ◽  
The Tibetan Plateau ◽  
Longitudinal Gradients ◽  
Leaf Stoichiometry ◽  
The Impact ◽  
The Vertical Distribution ◽  
Leaf N

Abstract. Understanding the leaf stoichiometric patterns is crucial for improving predictions on plant responses to environmental changes. Leaf stoichiometry of terrestrial ecosystems has been widely investigated along latitudinal and longitudinal gradients. Still, very little is known on the vertical distribution of leaf C : N : P and the relative effects of environmental parameters, especially for shrubs. Here, we analyzed the shrub leaf C, N and P patterns in 125 mountainous sites over an extensive altitudinal gradient (523–4685 m) on the Tibetan Plateau. Results showed that the shrub leaf C and C : N were 7.3 %–47.5 % higher than those of other regional and global flora, whereas the leaf N and N : P were 10.2 %–75.8 % lower. Leaf C increased with rising altitude and decreasing temperature, supporting the physiological acclimation mechanism that high leaf C (e.g., alpine or evergreen shrub) could balance the cell osmotic pressure and resist freezing. The largest leaf N and high leaf P occurred in valley region (altitude 1500 m), likely due to the large nutrient leaching from higher elevations, faster litter decomposition and nutrient resorption ability of deciduous broadleaf shrub. Leaf N : P ratio further indicated increasing N limitation at higher altitudes. Interestingly, the drought severity was the only climatic factor positively correlated with leaf N and P, which was more appropriate for evaluating the impact of water status than precipitation. Among the shrub ecosystem and functional types (alpine, subalpine, montane, valley, evergreen, deciduous, broadleaf, and conifer), their leaf element contents and responses to environments were remarkably different. Shrub type was the largest contributor to the total variations in leaf stoichiometry, while climate indirectly affected the leaf C : N : P via its interactive effects on shrub type or soil. Collectively, the large heterogeneity in shrub type was the most important factor explaining the overall leaf C : N : P variations, despite the broad climate gradient on the plateau. Temperature- and drought-induced shift of shrub type distribution will influence the nutrient accumulation in mountainous shrubs.

scholarly journals Identifying optical turbulence profiles for realistic tomographic error in adaptive optics

2019 ◽  
Vol 488 (1) ◽  
pp. 213-221 ◽  
Author(s):  
O J D Farley ◽  
J Osborn ◽  
T Morris ◽  
T Fusco ◽  
B Neichel ◽  
...  
Keyword(s):  
Vertical Distribution ◽  
Adaptive Optics ◽  
Compute Tomographic ◽  
Distribution Profile ◽  
Statistical Sample ◽  
Large Telescopes ◽  
The Impact ◽  
First Time ◽  
The Vertical Distribution ◽  
Performance Estimates

ABSTRACT For extremely large telescopes, adaptive optics will be required to correct the Earth’s turbulent atmosphere. The performance of tomographic adaptive optics is strongly dependent on the vertical distribution (profile) of this turbulence. An important way in which this manifests is the tomographic error, arising from imperfect measurement and reconstruction of the turbulent phase at altitude. Conventionally, a small number of reference profiles are used to obtain this error in simulation; however these profiles are not constructed to be representative in terms of tomographic error. It is therefore unknown whether these simulations are providing realistic performance estimates. Here, we employ analytical adaptive optics simulation that drastically reduces computation times to compute tomographic error for 10 691 measurements of the turbulence profile gathered by the Stereo-SCIDAR instrument at ESO Paranal. We assess for the first time the impact of the profile on tomographic error in a statistical manner. We find, in agreement with previous work, that the tomographic error is most directly linked with the distribution of turbulence into discrete, stratified layers. Reference profiles are found to provide mostly higher tomographic error than expected, which we attribute to the fact that these profiles are primarily composed of averages of many measurements resulting in unrealistic, continuous distributions of turbulence. We propose that a representative profile should be defined with respect to a particular system, and that as such simulations with a large statistical sample of profiles must be an important step in the design process.

The stability of vertical distribution profiles of insects in air layers near the ground

2000 ◽  
Vol 78 (12) ◽  
pp. 2167-2173 ◽  
Author(s):  
Gilles Boiteau ◽  
Walter PL Osborn ◽  
Xingyao Xiong ◽  
Yves Bousquet
Keyword(s):  
Apis Mellifera ◽  
Vertical Distribution ◽  
Coccinella Septempunctata ◽  
Lygus Lineolaris ◽  
Air Layers ◽  
Insect Monitoring ◽  
Regression Slopes ◽  
The Stability ◽  
The Impact ◽  
The Vertical Distribution

The vertical distribution of insect orders, families, and species captured over 10 elevations from the ground to 15 m over 4 years in a potato agro-ecosystem differed considerably within and between taxa. Regression slopes representing these aerial profiles remained similar over the 4 years of the study for orders Thysanoptera, Neuroptera, and Psocoptera, changed considerably for Hemiptera, Homoptera and Ephemeroptera, and were statistically non-homogeneous for Coleoptera, Hymenoptera, Diptera, Lepidoptera, Trichoptera, and Plecoptera. The slopes of the aerial profiles for families remained similar over the years for Carabidae and Elateridae, changed for Staphylinidae, Meloidae, and Scarabeidae, but were statistically non-homogeneous for Coccinellidae, Miridae, and Aphididae. The slopes of the aerial profiles for insect species were similar across years for Coccinella septempunctata L., Melanotus similis (Kirby), and Anatis mali Say, changed for Pyrrhalta luteola (Mull.), Ctenicera pulchra LeConte, Ctenicera tarsalis Melsheimer, Coccinella trifasciata perplexa Muls., Lygus lineolaris (P. de B.), Ctenicera appropinquans Randall, Apis mellifera L., and Adalia bipunctata (L.), but were significantly non-homogeneous only for Hippodamia convergens G.-M. Although most profiles obtained for insect orders in this study were remarkably similar to those reported in the literature, the level of between-year variation at our study site suggests that there is considerable overlap between profiles at all taxon levels. Vertical aerial profiles cannot be considered sufficiently characteristic of the species, family, or order across years for use as indicators of change in biodiversity. The impact of these results on insect monitoring are discussed.

Evaluation of a high resolution regional atmospheric chemistry model using MAX-DOAS and in situ NO2 measurements

2021 ◽  
Author(s):  
Vinod Kumar ◽  
Julia Remmers ◽  
Steffen Beirle ◽  
Astrid Kerkweg ◽  
Jos Lelieveld ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
High Resolution ◽  
Vertical Distribution ◽  
Atmospheric Chemistry ◽  
Pearson Correlation ◽  
Surface Concentration ◽  
Ozone Production ◽  
Vertical Column ◽  
The Impact ◽  
The Vertical Distribution

<p>Regional atmospheric chemistry models are adopted for simulating concentrations of atmospheric components at high resolution and quantifying the impact of localized emissions (e.g. industrial and urban clusters) on the non-linear chemical processes, e.g. ozone production. However, their evaluation is challenging due to the limited availability of high spatiotemporally resolved reference datasets. For the same reason, the vertical distribution of pollutants simulated by the model is especially arduous to assess.</p><p>Here, we present regional atmospheric chemistry model studies with spatial resolution up to 2.2 × 2.2 km<sup>2</sup> focused around Germany for May 2018 using the MECO(n) model system. Using a network of surface concentration measurements at background, near traffic and industrial locations, we evaluate the spatial distribution of NO<sub>2</sub> simulated by the model. The highly resolved model together with a comparable resolution and up-to-date input emissions inventory, was found to perform best in reproducing the spatial distribution of NO<sub>2</sub> surface volume mixing ratios (VMRs). We propose a computationally efficient approach to account for the diurnal and day of the week variability of input anthropogenic emissions (e.g. from road transport), which proved to be crucial for resolving the temporal variability of NO<sub>2</sub> surface VMRs.</p><p>The simulated NO<sub>2</sub> tropospheric vertical column densities were evaluated by employing the measurements of a 4-azimuth MAX-DOAS instrument in Mainz. Generally, such comparisons do not account for the spatial sensitivity volume of the MAX-DOAS measurements, the change of sensitivity within this volume and the spatial heterogeneity of NO<sub>2</sub>. We therefore apply a consistent approach of comparison of the differential slant column densities (dSCDs), which overcomes these limitations. Moreover, the dSCDs are obtained for several elevation and azimuth angles, which are characterized by distinctive sensitivity for different vertical levels within the boundary layer and different horizontal representativeness. Hence, also an evaluation of the model in simulating the vertical distribution of NO<sub>2</sub> can be performed with this approach using continuous MAX-DOAS measurements spanning long time periods. We found that the model performs well with respect to the measured dSCDs at low elevation angles (< 8°) with an overall bias between +14 and -9%, and Pearson correlation coefficients between 0.5 and 0.8 for the different azimuth viewing directions.</p>

scholarly journals News Soybean Sowing Arrangements on Spray and Control of Asian Rust

2019 ◽  
Vol 11 (5) ◽  
pp. 206
Author(s):  
Diego M. de Souza ◽  
Leidiane C. Carvalho ◽  
Marina M. Carvalho ◽  
Regiane C. O. de F. Bueno ◽  
Carlos G. Raetano
Keyword(s):  
Vertical Distribution ◽  
Disease Severity ◽  
Spray Deposition ◽  
Soybean Rust ◽  
Application Techniques ◽  
Soybean Plants ◽  
And Control ◽  
The Impact ◽  
The Vertical Distribution ◽  
Number Of Branches

Asian soybean rust (ASR) is one of the most severe diseases of the soybean crop, and the use of fungicides is the main form of control. Among the updates of soybean production system is adoption of new sowing arrangements. However are still incipient the studies to combine soybean sowing arrangements and pesticide spraying techniques on phytosanitary treatments on this crop. Therefore, the study aimed to evaluate the impact of different soybean sowing arrangements on spraying, ASR control, agronomic parameters and yield. The experimental design was randomized blocks in the subdivided plots scheme, with five sowing arrangements and two application techniques (with and without adjuvant). The spray deposition and coverage levels, the vertical distribution of leaves in the plants on different sowing arrangements, were evaluated the ASR disease severity and the productivity. Spraying is not affected by sowing arrangements. The adjuvant increased spray coverage. The vertical distribution of the leaves and number of branches in the soybean plants is affected by the sowing arrangement. The disease severity and yield were not affected by sowing arrangements.

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