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  • 1
    Publication Date: 2011-03-30
    Description: The capability of Weather Research and Forecasting (WRF) model in the simulation of cirrus clouds has been examined, with a focus on the effects of radiative processes and vertical model resolution. We incorporate in WRF a new radiation module, referred to as the Fu-Liou-Gu scheme, which is an improvement and refinement based on the Fu-Liou scheme, particularly in reference to parameterization of the single-scattering properties of ice crystal size and shape. We conducted a number of real-time WRF simulations for cirrus cases that were observed in the coastal and western United States on 29–30 March 2007, and we compared these with available observations from Moderate Resolution Imaging Spectroradiometer (MODIS) and GOES visible and IR images over the same areas. Simulation results show that WRF is capable of generating reasonable cirrus cloud fields and their movement and dissipation processes, especially those associated with the large-scale frontal system. Radiative processes are important in cirrus cloud simulations by affecting the vertical thermal structure and hence convection. The newly implemented radiation module, the Fu-Liou-Gu scheme, has been demonstrated to work well in WRF and can be effectively used for studies related to cirrus cloud formation and evolution and aerosol-cloud-radiation interactions. With the newly implemented radiation scheme, the simulations of cloud cover and cloud and ice water path (CWP and IWP) have been improved for cirrus clouds, with a more consistent comparison with the corresponding MODIS observations in terms of CWP and IWP means and CWP frequency distribution, especially for optically thin cirrus with an improvement of about 20% in simulated mean IWP. The model-simulated ice crystal sizes have also been shown to be comparable to those determined from MODIS cloud products. Finally, we have demonstrated that model vertical resolution plays a significant role in cirrus cloud simulation in terms of altering vertical velocity field and the associated regional circulation.
    Print ISSN: 0148-0227
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 2
    Publication Date: 2014-06-03
    Description: A stochastic approach has been developed to model the positions of BC/dust internally mixed with two snow-grain types: hexagonal plate/column (convex) and Koch snowflake (concave). Subsequently, light absorption and scattering analysis can be followed by means of an improved geometric-optics approach coupled with Monte Carlo photon tracing to determine BC/dust single-scattering properties. For a given shape (plate, Koch snowflake, spheroid, or sphere), the action of internal mixing absorbs substantially more light than external mixing. The snow-grain shape effect on absorption is relatively small, but its effect on asymmetry factor is substantial. Due to a greater probability of intercepting photons, multiple inclusions of BC/dust exhibit a larger absorption than an equal-volume single inclusion. The spectral absorption (0.2 – 5  μ m) for snow grains internally mixed with BC/dust is confined to wavelengths shorter than about 1.4  μ m, beyond which ice absorption predominates. Based on the single-scattering properties determined from stochastic and light absorption parameterizations and using the adding/doubling method for spectral radiative transfer, we find that internal mixing reduces snow albedo substantially more than external mixing and that the snow-grain shape plays a critical role in snow albedo calculations through its forward scattering strength. Also, multiple inclusion of BC/dust significantly reduces snow albedo as compared to an equal-volume single sphere. For application to land/snow models, we propose a two-layer spectral snow parameterization involving contaminated fresh snow on top of old snow for investigating and understanding the climatic impact of multiple BC/dust internal mixing associated with snow grain metamorphism, particularly over mountain/snow topography.
    Print ISSN: 0148-0227
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 3
    Publication Date: 2019
    Description: Abstract The United Nations has reported that 55% of the global population resides in urban areas, and 68% of the population is expected to be urban dwellers by 2050. Urbanization has critical implications for global land cover. Relevant literature has provided evidence attributing climatic effects to urban expansion; however, few studies have investigated the effect on public health and pollutant sensitivity to emissions. This study aimed to characterize the effect of urbanization‐induced changes in regional climate on ozone (O3), to evaluate ozone sensitivity to nitrogen oxide (NOx) and volatile organic compound (VOC) emissions, and to estimate premature mortalities due to O3 exposure. We employed atmospheric models with the higher‐order decoupled direct method (HDDM) to simulate effects of urbanization on O3 and to determine O3 sensitivity to NOx and VOC emissions. China‐specific concentration response functions were utilized to estimate cardiovascular and respiratory mortalities due to ozone exposure. Urbanization increased O3, which translated to a 39.6% increase in O3‐induced premature mortality (1,100 deaths). Moreover, O3 has become less/more sensitive to unit changes in NOx and VOC emissions in various cities. Urban greening may reduce urban temperature, but it may increase O3 in some cities due to the additional VOC emissions of greening. These findings highlight the strong interactions between land‐use policies, urban climate adaptation strategies, and air quality policies, suggesting the need of cobeneficial strategies and policies. We proposed a “precision environmental management” concept that emphasizes the importance of considering the specific atmospheric condition and composition of a city when formulating its environmental policies.
    Print ISSN: 2169-897X
    Electronic ISSN: 2169-8996
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 4
    Publication Date: 2017-06-01
    Description: Four compounds 1 to 4 (folic acid, methotrexate and 2 dyes) were used to interact with folate receptor (FR)α and FRβ. The interaction structures and binding energies of the bound complexes were investigated. In order to analyze the differences between FRα and FRβ complexes, the details of the weak intermolecular interactions were analyzed, and the frontier orbital properties of the FR complexes were studied by a dispersion complemented density functional tight-binding method. By comparing the different interaction properties of the 4 compounds with FRα and FRβ, the basic strategies for design of novel compound targeted with FR subtype were suggested. Further, a novel compound with high selectively with FRα based on compound 3 was designed to illustrate our conclusion. These data should be helpful for the design of novel molecules with extreme discerningly with FRα and FRβ. The variety of interaction models between ligands and FRα or FRβ was studied. By the difference between FRα and FRβ complexes, a novel compound with high selectively with FRα was designed, which will improve the recognition accuracy of the tumor cell and the efficiency of targeted drug delivery systems.
    Print ISSN: 0894-3230
    Electronic ISSN: 1099-1395
    Topics: Chemistry and Pharmacology , Physics
    Published by Wiley
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  • 5
    Publication Date: 2015-07-24
    Description: ABSTRACT Exercise is dependent on adequate oxygen supply for mitochondrial respiration in both cardiac and locomotor muscle. To determine whether skeletal myofiber VEGF is critical for regulating exercise capacity, independent of VEGF function in the heart, ablation of the VEGF gene was targeted to skeletal myofibers (skmVEGF-/-) during embryogenesis (∼ E9.5), leaving intact VEGF expression by all other cells in muscle. In adult mice, VEGF levels were decreased in the soleus (by 65%), plantaris (94%), gastrocnemius (74%), EDL (99%) and diaphragm (64%) (p 〈 0.0001, each muscle). VEGF levels were unchanged in the heart. Treadmill speed (WT 86  ± 4 cm/sec., skmVEGF-/- 70 ± 5 cm/sec., p = 0.006) and endurance (WT 78 ± 24 min., skmVEGF-/- 18 ± 4 min., p = 0.0004) were severely limited in skmVEGF-/- mice in contrast to minor effect of conditional skmVEGF gene deletion in the adult. Body weight was also reduced (WT 22.8 ± 1.6 g, skmVEGF-/-, 21.1 ± 1.5, p = 0.02), but the muscle mass/body weight ratio was unchanged. The capillary/fiber ratio was lower in skmVEGF-/- plantaris (WT 1.51 ± 0.12, skmVEGF-/- 1.16 ± 0.20, p = 0.01), gastrocnemius (WT 1.61 ± 0.08, skmVEGF-/- 1.39 ± 0.08, p = 0.01), EDL (WT 1.36 ± 0.07, skmVEGF-/- 1.14 ± 0.13, p = 0.03) and diaphragm (WT 1.39 ± 0.18, skmVEGF-/- 0.79 ± 0.16, p = 0.0001) but, not in soleus. Cardiac function (heart rate, maximal pressure, maximal dP/dt, minimal dP/dt,) in response to dobutamine was not impaired in anesthetized skmVEGF-/- mice. Isolated soleus and EDL fatigue times were 16% and 20% (p 〈 0.02) longer, respectively, in skmVEGF-/- mice than the WT group. These data suggest that skeletal myofiber VEGF expressed during development is necessary to establish capillary networks that allow maximal exercise capacity. This article is protected by copyright. All rights reserved
    Electronic ISSN: 1097-4652
    Topics: Biology , Medicine
    Published by Wiley
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  • 6
    Publication Date: 2019
    Description: Abstract Severe geomagnetic storms caused by the solar wind disturbances have harmful influences on the operation of modern equipment and systems. The modeling and forecasting of AE index are extremely useful to understand the geomagnetic substorms. This study presents a novel cloud‐nonlinear autoregressive with exogenous input (NARX) model to predict AE index 1 hr ahead. The cloud‐NARX model provides AE index forecasting results, with a correlation coefficient of 0.87 on the data of whole year 2015. The benchmarks on the data of the two interested periods of 17–21 March 2015 and 22–26 June 2015 are presented. The presented model uses uncertainty “cloud” model and cloud transformation to quantify the uncertainty throughout the structure detection, parameter estimation, and model prediction. The new predicted band can be generated to forecast AE index with confidence interval. The proposed method provides a new way to evaluate the model based on uncertainty analysis, revealing the reliability of model, and visualize the bias of model prediction.
    Print ISSN: 1539-4964
    Electronic ISSN: 1542-7390
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 7
    Publication Date: 2019
    Description: Abstract Severe geomagnetic storms caused by the solar wind disturbances have harmful influences on the operation of modern equipment and systems. The modeling and forecasting of AE index are extremely useful to understand the geomagnetic substorms. This study presents a novel cloud‐nonlinear autoregressive with exogenous input (NARX) model to predict AE index 1 hr ahead. The cloud‐NARX model provides AE index forecasting results, with a correlation coefficient of 0.87 on the data of whole year 2015. The benchmarks on the data of the two interested periods of 17–21 March 2015 and 22–26 June 2015 are presented. The presented model uses uncertainty “cloud” model and cloud transformation to quantify the uncertainty throughout the structure detection, parameter estimation, and model prediction. The new predicted band can be generated to forecast AE index with confidence interval. The proposed method provides a new way to evaluate the model based on uncertainty analysis, revealing the reliability of model, and visualize the bias of model prediction.
    Print ISSN: 2169-9380
    Electronic ISSN: 2169-9402
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 8
    Publication Date: 2017-06-16
    Description: We explore the phase relationship between the poloidal mode ULF wave electric field oscillations and drift-bounce resonant oxygen ions under the resonant condition of N=2 at the magnetic equator. Using Cluster data from 2001 to 2004, we identify 55 fundamental poloidal mode wave events, among which 42 show “negative slope" pitch angle dispersion signatures in the southern hemisphere, 11 show “positive slope" dispersion in the northern hemisphere, and 2 near-equatorial events are associated with in-phase field-aligned signatures. For each event, the off-equatorial resonant ions are traced along their bouncing trajectories to determine the last time they moved across the equator. The resulting time-series of the resonant oxygen ion fluxes at the equator are found to be statistically in anti-phase with the wave electric fields. The resonant ion flux variation depends on both ion energy change and radial transportation. This anti-phase relationship in statistics suggests two possibilities: (1) the fundamental poloidal mode wave electric fields are generally characterized by electric field intensity peaking near the magnetic equator if the flux variation is mainly caused by energy change; (2) the radial gradient of phase space density is positive if the flux variation caused by radial transportation is dominant .
    Print ISSN: 0148-0227
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 9
    Publication Date: 2017-01-24
    Print ISSN: 1351-0754
    Electronic ISSN: 1365-2389
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by Wiley
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