Impact of Asian Dust Aerosol and Surface Albedo on Photosynthetically Active Radiation and Surface Radiative Balance in Dryland Ecosystems

We investigated the extent to which Asian dust can affect vegetation in dryland ecosystems through altering photosynthetically active radiation (PAR) and shortwave and longwave radiation components of the surface energy balance. Results show that dust decreases the surface radiative balance and total PAR. The diffuse component of PAR, however, increases with increasing dust load but then decreases after reaching a maximum at a certain optimum condition. The forcing efficiency ranges from −67.7 to −82.2 Wm-2 τ0.5      −1 in total PAR and from −68.8 to −122.1 Wm-2 τ0.5      −1 in surface radiative balance. The ratio of total PAR to downwelling shortwave flux remains nearly constant (0.45±4%) similar to other aerosol types, while the ratio for the diffuse faction of PAR exhibits significant variations. The impact of dust on the gross photosynthetic rate varies among different types of crops. C4 plants such as corn tend to be less sensitive to the dust optical properties compared to C3 plants such as soybean and wheat

On the Effect of Dust Particles on Global Cloud Condensation Nuclei and Cloud Droplet Number

Aerosol-cloud interaction studies to date consider aerosol with a substantial fraction of soluble material as the sole source of cloud condensation nuclei (CCN). Emerging evidence suggests that mineral dust can act as good CCN through water adsorption onto the surface of particles. This study provides a first assessment of the contribution of insoluble dust to global CCN and cloud droplet number concentration (CDNC). Simulations are carried out with the NASA Global Modeling Initiative chemical transport model with an online aerosol simulation, considering emissions from fossil fuel, biomass burning, marine, and dust sources. CDNC is calculated online and explicitly considers the competition of soluble and insoluble CCN for water vapor. The predicted annual average contribution of insoluble mineral dust to CCN and CDNC in cloud-forming areas is up to 40 and 23.8%, respectively. Sensitivity tests suggest that uncertainties in dust size distribution and water adsorption parameters modulate the contribution of mineral dust to CDNC by 23 and 56%, respectively. Coating of dust by hygroscopic salts during the atmospheric aging causes a twofold enhancement of the dust contribution to CCN; the aged dust, however, can substantially deplete in-cloud supersaturation during the initial stages of cloud formation and can eventually reduce CDNC. Considering the hydrophilicity from adsorption and hygroscopicity from solute is required to comprehensively capture the dust-warm cloud interactions. The framework presented here addresses this need and can be easily integrated in atmospheric models

АЛГОРИТМ ОБРАБОТКИ СИГНАЛОВ В РАДИОЛОКАЦИОННОЙ СИСТЕМЕ С НЕПРЕРЫВНЫМ ЧАСТОТНО-МОДУЛИРОВАННЫМ ИЗЛУЧЕНИЕМ В ИНТЕРЕСАХ ОБНАРУЖЕНИЯ МАЛОЗАМЕТНЫХ ВОЗДУШНЫХ ОБЪЕКТОВ, ОЦЕНКИ ИХ ДАЛЬНОСТИ И СКОРОСТИ ДВИЖЕНИЯ

Nowadays the interest in search of ways of improving the efficiency of small radar cross-section aerial objects detection and localization rises against the background of widespread use of light and unmanned aerial vehi-cles. As a result, researchers pay attention to radar systems (RS) with continuous linear frequency modulation (linear FM) signal. The use of such signals gives the measurable opportunity to reduce radar system peak-speech power and to cut the cost and weightsize parameters of the RS. The paper observes low-power ground based radar implementation prospects for purposes of detection and estimation of motion rates of small-sized aerial objects. The proposed algorithm of radar signals processing enables to simplify the detection of such tar-gets. The paper reveals the structure and defines the steps of the algorithm. The fundamental for the algorithm under consideration is the method of the range-Doppler image composition of the scanned area using digital signal processing. The paper presents the results of the algorithm operation in the low-power RS of C-band radar, obtained by processing of quadrotor echo-signals during the real experiment. The results show successful solvation of the applied problem of detection and tracking on the small-sized aerial object with the radar cross-section equal to less than 0.5 m2 and the spectrum of secondary radiation characterized by the expressed multimodality. The results of the experiment validate the application of the algorithm and demonstrate the possibility of the algorithm implementation in design of portable RS and automated target acquisition centers for detecting and tracking of the small-sized aerial targets (both, single as multi agent) with the information display on operator control panel.На фоне повсеместного использования беспилотных летательных аппаратов и легкомоторной авиации растет интерес к поиску путей повышения эффективности локализации и определения параметров движения воздушных объектов с малой эффективной площадью рассеяния. В связи с этим закономерно внимание к радиолокационным системам (РЛС) с непрерывным линейно-частотно-модулированным (ЛЧМ) излучением. Использование таких зондирующих сигналов позволяет значительно снизить пиковую мощность РЛС и уменьшить ее массогабаритные и стоимостные характеристики. Статья посвящена исследованию перспективы применения маломощной наземной РЛС с непрерывным ЛЧМ-сигналом в интересах обнаружения, а также определения координат и параметров движения малозаметных воздушных объектов. Предложен алгоритм обработки радиолокационных сигналов, позволяющий упростить процедуру обнаружения таких целей, раскрыта структура и приведено описание этапов алгоритма. В основе рассматриваемого алгоритма лежит методика формирования дальностно-доплеровского портрета зоны обзора с использованием цифровой обработки сигнала. Приведены результаты применения алгоритма в маломощной РЛС С-диапазона, полученные при обработке эхосигналов квадрокоптера, зарегистрированных в ходе натурного эксперимента. Показано успешное решение практической задачи обнаружения и сопровождения малоразмерного воздушного объекта с эффективной площадью рассеяния до 0.5 м2, спектр вторичного излучения которого характеризуется выраженной многомодальностью. Результаты эксперимента подтвердили практическую значимость предлагаемого алгоритма и возможность его реализации при создании мобильных переносных радиолокационных комплексов и постов автоматического обнаружения и сопровождения малозаметных одиночных и групповых целей с выдачей информации на пульт оператора

3ARM: A Fast, Accurate Radiative Transfer Model for use in Climate Models

A new radiative transfer model combining the efforts of three groups of researchers is discussed. The model accurately computes radiative transfer in a inhomogeneous absorbing, scattering and emitting atmospheres. As an illustration of the model, results are shown for the effects of dust on the thermal radiation

The Northern Eurasia Earth Science Partnership: An Example of Science Applied to Societal Needs

Northern Eurasia, the largest landmass in the northern extratropics, accounts for ~20% of the global land area. However, little is known about how the biogeochemical cycles, energy and water cycles, and human activities specific to this carbon-rich, cold region interact with global climate. A major concern is that changes in the distribution of land-based life, as well as its interactions with the environment, may lead to a self-reinforcing cycle of accelerated regional and global warming. With this as its motivation, the Northern Eurasian Earth Science Partnership Initiative (NEESPI) was formed in 2004 to better understand and quantify feedbacks between northern Eurasian and global climates. The first group of NEESPI projects has mostly focused on assembling regional databases, organizing improved environmental monitoring of the region, and studying individual environmental processes. That was a starting point to addressing emerging challenges in the region related to rapidly and simultaneously changing climate, environmental, and societal systems. More recently, the NEESPI research focus has been moving toward integrative studies, including the development of modeling capabilities to project the future state of climate, environment, and societies in the NEESPI domain. This effort will require a high level of integration of observation programs, process studies, and modeling across disciplines

The Construction of Quantum Field Operators: Something of Interest

We draw attention to some tune problems in constructions of the quantum-field operators for spins 1/2 and 1. They are related to the existence of negative-energy and acausal solutions of relativistic wave equations. Particular attention is paid to the chiral theories, and to the method of the Lorentz boosts.Comment: 31 pages, no figures. The invited talk at the VIII International Workshop "Applied Category Theory. Graph-Operad-Logic", San Blas, Nayarit, Mexico, January 9-16, 2010, and at the 6th International Conference on the Dark Side of the Universe (DSU2010), Leon, Gto, Mexico, June 1-6, 201

Extra Dirac Equations

This paper has rather a pedagogical meaning. Surprising symmetries in the $(j,0)\oplus (0,j)$ Lorentz group representation space are analyzed. The aim is to draw reader's attention to the possibility of describing the particle world on the ground of the Dirac "doubles". Several tune points of the variational principle for this kind of equations are briefly discussed.Comment: REVTeX 3.0, 14p

Management of singlet and triplet excitons for efficient white organic light-emitting devices

Lighting accounts for approximately 22 per cent of the electricity consumed in buildings in the United States, with 40 per cent of that amount consumed by inefficient (similar to 15 lm W-1) incandescent lamps(1,2). This has generated increased interest in the use of white electroluminescent organic light-emitting devices, owing to their potential for significantly improved efficiency over incandescent sources combined with low-cost, high-throughput manufacturability. The most impressive characteristics of such devices reported to date have been achieved in all-phosphor-doped devices, which have the potential for 100 per cent internal quantum efficiency(2): the phosphorescent molecules harness the triplet excitons that constitute three-quarters of the bound electron-hole pairs that form during charge injection, and which (unlike the remaining singlet excitons) would otherwise recombine non-radiatively. Here we introduce a different device concept that exploits a blue fluorescent molecule in exchange for a phosphorescent dopant, in combination with green and red phosphor dopants, to yield high power efficiency and stable colour balance, while maintaining the potential for unity internal quantum efficiency. Two distinct modes of energy transfer within this device serve to channel nearly all of the triplet energy to the phosphorescent dopants, retaining the singlet energy exclusively on the blue fluorescent dopant. Additionally, eliminating the exchange energy loss to the blue fluorophore allows for roughly 20 per cent increased power efficiency compared to a fully phosphorescent device. Our device challenges incandescent sources by exhibiting total external quantum and power efficiencies that peak at 18.7 +/- 0.5 per cent and 37.6 +/- 0.6 lm W-1, respectively, decreasing to 18.4 +/- 0.5 per cent and 23.8 +/- 0.5 lm W-1 at a high luminance of 500 cd m(-2).Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/62889/1/nature04645.pd