Sink mechanism for significantly low level of ozone over the Arabian Sea during monsoon

Measurement of surface ozone over the Arabian Sea during the southwest monsoon season (June-September) of 2002 has shown an unusually low level of ozone with an overall average of 9 nmol/mol. Such a low level of ozone could not be explained by simulations using a three-dimensional chemistry transport model, Model for Ozone and Related Tracers (MOZART), which accounts for the known processes of advective transport and includes a standard photochemical mechanism. Thus, for the Arabian Sea region, we propose for the first time that destruction of ozone by reactive halides released from sea salt aerosols is the sink mechanism which played a crucial role in ensuring the significantly low ozone level over the Arabian Sea. Theoretical calculations constrained by observations have shown that, on average, ozone losses due to catalytic action of halogens and due to photolysis plus chemical reaction amount to 2.15 nmol mol-1d-1 and 4.64 nmol mol-1d-1, respectively

Instability and Fluctuations of Flux Lines with Point Impurities in a Parallel Current

A parallel current can destabilize a single flux line (FL), or an array of FLs. We consider the effects of pinning by point impurities on this instability. The presence of impurities destroys the long-range order of a flux lattice, leading to the so called Bragg glass (BrG) phase. We first show that the long-range topological order of the BrG is also destroyed by a parallel current. Nonetheless, some degree of short-range order should remain, whose destruction by thermal and impurity fluctuations, as well as the current, is studied here. To this end, we employ a cage model for a single FL in the presence of impurities and current, and study it analytically (by replica variational methods), and numerically (using a transfer matrix technique). The results are in good agreement, and in conjunction with a Lindemann criterion, provide the boundary in the magnetic field--temperature plane for destruction of short-range order. In all cases, we find that the addition of impurities or current (singly or in combination) leads to further increase in equilibrium FL fluctuations. Thus pinning to point impurities does not stabilize FLs in a parallel current $j_z$, although the onset of this instability is much delayed due to large potential barriers that diverge as $j_z^{-\mu}$.Comment: 10 pages, 6 figure

Procjene koncentracija lebdećih čestica PM1, PM2.5 i PM10 u Delhiju, Indija, na različitim vremenskim skalama

Daily, monthly, seasonal and annual moving means of PM1, PM2.5 and PM10 concentrations from August, 2007 to October, 2008 at Delhi (28º 35’ N; 77º 12’ E),the seventh populous megacity in the world are presented. PM1, PM2.5 and PM10 concentrations varied seasonally with atmospheric processes and the anthropogenic activities. PM10 decreases during monsoon by ~25–80 μg m–3 and PM1 and PM2.5 by ~10–15 μg m–3 from their pre-monsoon levels. Emissions from fireworks during Deepawali in the post-monsoon season increases PM1, PM2.5 and PM10 levels by 300, 350 and 400 μg m–3, respectively over their monsoon levels. Seasonal variation of mixing heights, temperatures, winds and rainfall, accountsfor the inter-annual variability of PM1, PM2.5, and PM10. Accordingly, wintertime PM1, PM2.5 and PM10 components contribute by ~30–33% to annual levels. PM10 in summer is higher by 8% to that of PM2.5 and by 9% to that of PM1. PM10 components in post-monsoon are lower by 5% to that of PM2.5 and by 7% to that ofPM1. Also, PM1, PM2.5 and PM10 levels were higher during October, 2008 thanthose in 2007, but their levels were almost remain the same in August and September of 2007 and 2008. Moving means of PM1, PM2.5 and PM10 and their concentrations in different seasons are useful in policy making decisions there¬upon aiming to improve the air quality in Delhi.Prikazani su dnevni, mjesečni, sezonski i godišnji klizni srednjaci koncentracijalebdećih čestica PM1, PM2.5 i PM10 za razdoblje od kolovoza 2007. do listopada 2008 uDelhiju, Indija (28º 35’ N; 77º 12’ E), po veličini sedmom velegradu na svijetu. Koncentracije lebdećih čestica PM1, PM2.5 i PM10 sezonski se mijenjaju u ovisnosti o atmosferskimprocesima i ljudskim aktivnostima. U odnosu na svoje predmonsunske vrijednosti koncentracije PM10 se smanjuju tijekom monsunskog razdoblja za ~25–80 μg m–3, a koncen¬tracije PM1 i PM2.5 za ~10–15 μgm–3. Vatrometi tijekom festivala Deepawali podižu razine koncentracija lebdećih čestica PM1, PM2.5 i PM10 u post-monsunskoj sezoni za 300, 350,odnosno 400 μg m–3 u odnosu na njihove vrijednosti u monsunskoj sezoni. Sezonska varijacija visine miješanja, temperature, vjetra i oborine doprinosi međugodišnjoj varijabilnosti PM1, PM2.5 i PM10. zimske razine PM1, PM2.5, i PM10 doprinose ~30–33% ukupnim vrijednostima. Koncentracije PM10 ljeti su više za 8% od onih za PM2.5 i za 9% od onih za PM1. Koncentracija frakcije PM10 u post-monsunskom razdoblju su niže za 5% od onih za PM2.5 i za 7% od onih za PM1. Također, koncentracije PM1, PM2.5 i PM10 bile su više tijekomlistopada 2008. od onih u 2007., ali su njihove razine ostale gotovo iste u kolovozu i rujnu2007. i 2008. Klizni srednjaci koncentracija PM1, PM2.5 i PM10 te vrijednosti koncentracija u različitim sezonama korisni su za donošenje propisa vezanih uz razine onečišćenjazraka, čiji je cilj poboljšanje kvalitete zraka u Delhiju

Variations in Mass of the PM 10 , PM 2.5 and PM 1 during the Monsoon and the Winter at New Delhi

ABSTRACT PM 10 , PM 2.5 and PM 1 mass concentrations have been measured at Delhi (28°35'N; 77°12'E) during the August to December 2007. The running mean of PM 10 , PM 2.5 and PM 1 data shows large variations. The PM 10 , PM 2.5 and PM 1 were ranged from 20 to 180 g/m 3 during the monsoon and from 100 to 500 g/m 3 during the winter (up to 1200 g/m 3 in November due to Deepavali fireworks). For the same running mean cycles, higher mass concentrations in the PM 10 , PM 2.5 and PM 1 were corresponded with peaks in the relative humidity and lower levels linked to peaks in the ambient temperature. The evolutions of PM 10 , PM 2.5 and PM 1 concentrations after the elapsed times are simulated with mean mass scavenging coefficients. These evolution patterns clearly show the difference in washout of PM 10 with impaction scavenging relative to those for PM 2.5 and PM 1 particles over different rainfall durations. Air-mass pathways traced with HYSPLIT model over the study area illustrates the nature of PM 10 , PM 2.5 and PM 1 levels with monsoon and winter airmass circulations over Delhi

Extensive Chaos in the Nikolaevskii Model

We carry out a systematic study of a novel type of chaos at onset ("soft-mode turbulence") based on numerical integration of the simplest one dimensional model. The chaos is characterized by a smooth interplay of different spatial scales, with defect generation being unimportant. The Lyapunov exponents are calculated for several system sizes for fixed values of the control parameter $\epsilon$. The Lyapunov dimension and the Kolmogorov-Sinai entropy are calculated and both shown to exhibit extensive and microextensive scaling. The distribution functional is shown to satisfy Gaussian statistics at small wavenumbers and small frequency.Comment: 4 pages (including 5 figures) LaTeX file. Submitted to Phys. Rev. Let

Radiative Forcing of Black Carbon over Delhi

The radiative effects of black carbon (BC) aerosols over New Delhi, the capital city of India, for the period August 2010–July 2011, have been investigated using Santa Barbara DISTORT Atmospheric Radiative Transfer (SBDART) model in the present paper. The monthly mean BC concentrations in Delhi, an urban location, vary in between 15.935 ± 2.06 μg m−3 (December 2010)–2.44 ± 0.58 μg m−3 (July 2011). The highest value for monthly mean BC forcing has been found to be in November 2010 (66.10 ± 6.86 Wm−2) and the lowest in July 2011 (23 ± 3.89 Wm−2). Being the host city for the XIX Commonwealth Games (CWG-2010), government of Delhi set up a plan to reduce emissions of air pollutants during Games, from 03 October to 14 October, 2010. But opposite to the expectations, the emission controls implemented were not sufficient to reduce the pollutants like black carbon (BC), and therefore relatively a high value of BC radiative forcing (44.36 ± 2.4) was observed during the month of October 2010

Synchronisation in Coupled Sine Circle Maps

We study the spatially synchronized and temporally periodic solutions of a 1-d lattice of coupled sine circle maps. We carry out an analytic stability analysis of this spatially synchronized and temporally periodic case and obtain the stability matrix in a neat block diagonal form. We find spatially synchronized behaviour over a substantial range of parameter space. We have also extended the analysis to higher spatial periods with similar results. Numerical simulations for various temporal periods of the synchronized solution, reveal that the entire structure of the Arnold tongues and the devil's staircase seen in the case of the single circle map can also be observed for the synchronized coupled sine circle map lattice. Our formalism should be useful in the study of spatially periodic behaviour in other coupled map lattices.Comment: uuencoded, 1 rextex file 14 pages, 3 postscript figure

Effect of noise on coupled chaotic systems

Effect of noise in inducing order on various chaotically evolving systems is reviewed, with special emphasis on systems consisting of coupled chaotic elements. In many situations it is observed that the uncoupled elements when driven by identical noise, show synchronization phenomena where chaotic trajectories exponentially converge towards a single noisy trajectory, independent of the initial conditions. In a random neural network, with infinite range coupling, chaos is suppressed due to noise and the system evolves towards a fixed point. Spatiotemporal stochastic resonance phenomenon has been observed in a square array of coupled threshold devices where a temporal characteristic of the system resonates at a given noise strength. In a chaotically evolving coupled map lattice with logistic map as local dynamics and driven by identical noise at each site, we report that the number of structures (a structure is a group of neighbouring lattice sites for whom values of the variable follow certain predefined pattern) follow a power-law decay with the length of the structure. An interesting phenomenon, which we call stochastic coherence, is also reported in which the abundance and lifetimes of these structures show characteristic peaks at some intermediate noise strength.Comment: 21 page LaTeX file for text, 5 Postscript files for figure

A generic travelling wave solution in dissipative laser cavity

A large family of cosh-Gaussian travelling wave solution of a complex Ginzburg–Landau equation (CGLE), that describes dissipative semiconductor laser cavity is derived. Using perturbation method, the stability region is identified. Bifurcation analysis is done by smoothly varying the cavity loss coefficient to provide insight of the system dynamics. He’s variational method is adopted to obtain the standard sech-type and the notso-explored but promising cosh-Gaussian type, travelling wave solutions. For a given set of system parameters, only one sech solution is obtained, whereas several distinct solution points are derived for cosh-Gaussian case. These solutions yield a wide variety of travelling wave profiles, namely Gaussian, near-sech, flat-top and a cosh-Gaussianwith variable central dip. A split-step Fourier method and pseudospectral method have been used for direct numerical solution of the CGLE and travelling wave profiles identical to the analytical profiles have been obtained. We also identified the parametric zone that promises an extremely large family of cosh-Gaussian travelling wave solutions with tunable shape. This suggests that the cosh-Gaussian profile is quite generic and would be helpful for further theoretical as well as experimental investigation on pattern formation, pulse dynamics andlocalization in semiconductor laser cavity