Optical and Physical Properties of Atmospheric Aerosols over the Bay of Bengal during ICARB

Simultaneous and collocated measurements of total and hemispherical backscattering coefficients (σ and β, respectively) at three wavelengths, mass size distributions, and columnar spectral aerosol optical depth (AOD) were made onboard an extensive cruise experiment covering, for the first time, the entire Bay of Bengal (BoB) and northern Indian Ocean. The results are synthesized to understand the optical properties of aerosols in the marine atmospheric boundary layer and their dependence on the size distribution. The observations revealed distinct spatial and spectral variations of all the aerosol parameters over the BoB and the presence of strong latitudinal gradients. The size distributions varied spatially, with the majority of accumulation modes decreasing from north to south. The scattering coefficient decreased from very high values (resembling those reported for continental/urban locations) in the northern BoB to very low values seen over near-pristine environments in the southeastern BoB. The average mass scattering efficiency of BoB aerosols was found to be 2.66 ± 0.1 m2 g−1 at 550 nm. The spectral dependence of columnar AOD deviated significantly from that of the scattering coefficients in the northern BoB, implying vertical heterogeneity in the aerosol type in that region. However, a more homogeneous scenario was observed in the southern BoB. Simultaneous lidar and in situ measurements onboard an aircraft over the ocean revealed the presence of elevated aerosol layers of enhanced extinction at altitudes of 1 to 3 km with an offshore extent of a few hundred kilometers. Back-trajectory analyses showed these layers to be associated with advection from west Asia and western India. The large spatial variations and vertical heterogeneity in aerosol properties, revealed by the present study, need to be included in the regional radiative forcing over the Bay of Bengal.

Diversity and Distribution of Conidae from the TamilNadu Coast of India (Mollusca: Caenogastropoda: Conidae)

A survey of the marine gastropod genus Conus Linnaeus was conducted along the TamilNadu Coast of India to explore the regional geographic distribution and diversity. The 60 species observed increased the number of Indian Conidae from 77 to 81. Conus imperialis Linne, C. mitratus Hwass in Bruguiere, C. striolatus Kiener and C. violaceus Gmelin are newly recorded from the study area. Conus amadis Gmelin was the most widely distributed species. The highest diversity (48 species) occurred in the Gulf of Mannar, followed by 22 species from northern, six from southern, and five from the Palk Bay regions. We suggest that the rich diversity recorded in the Gulf of Mannar reflects the physical conditions, microhabitats and required resources such as food and shelter that favour the occurrence of the large number of Conus species.

Distribution of non-biting midges (Diptera, Chironomidae) in subarctic lakes of Finnish Lapland applications in lake classification and palaeolimnology

Climate change contributes directly or indirectly to changes in species distributions, and there is very high confidence that recent climate warming is already affecting ecosystems. The Arctic has already experienced the greatest regional warming in recent decades, and the trend is continuing. However, studies on the northern ecosystems are scarce compared to more southerly regions. Better understanding of the past and present environmental change is needed to be able to forecast the future. Multivariate methods were used to explore the distributional patterns of chironomids in 50 shallow (≤ 10m) lakes in relation to 24 variables determined in northern Fennoscandia at the ecotonal area from the boreal forest in the south to the orohemiarctic zone in the north. Highest taxon richness was noted at middle elevations around 400 m a.s.l. Significantly lower values were observed from cold lakes situated in the tundra zone. Lake water alkalinity had the strongest positive correlation with the taxon richness. Many taxa had preference for lakes either on tundra area or forested area. The variation in the chironomid abundance data was best correlated with sediment organic content (LOI), lake water total organic carbon content, pH and air temperature, with LOI being the strongest variable. Three major lake groups were separated on the basis of their chironomid assemblages: (i) small and shallow organic-rich lakes, (ii) large and base-rich lakes, and (iii) cold and clear oligotrophic tundra lakes. Environmental variables best discriminating the lake groups were LOI, taxon richness, and Mg. When repeated, this kind of an approach could be useful and efficient in monitoring the effects of global change on species ranges. Many species of fast spreading insects, including chironomids, show a remarkable ability to track environmental changes. Based on this ability, past environmental conditions have been reconstructed using their chitinous remains in the lake sediment profiles. In order to study the Holocene environmental history of subarctic aquatic systems, and quantitatively reconstruct the past temperatures at or near the treeline, long sediment cores covering the last 10000 years (the Holocene) were collected from three lakes. Lower temperature values than expected based on the presence of pine in the catchment during the mid-Holocene were reconstructed from a lake with great water volume and depth. The lake provided thermal refuge for profundal, cold adapted taxa during the warm period. In a shallow lake, the decrease in the reconstructed temperatures during the late Holocene may reflect the indirect response of the midges to climate change through, e.g., pH change. The results from three lakes indicated that the response of chironomids to climate have been more or less indirect. However, concurrent shifts in assemblages of chironomids and vegetation in two lakes during the Holocene time period indicated that the midges together with the terrestrial vegetation had responded to the same ultimate cause, which most likely was the Holocene climate change. This was also supported by the similarity in the long-term trends in faunal succession for the chironomid assemblages in several lakes in the area. In northern Finnish Lapland the distribution of chironomids were significantly correlated with physical and limnological factors that are most likely to change as a result of future climate change. The indirect and individualistic response of aquatic systems, as reconstructed using the chironomid assemblages, to the climate change in the past suggests that in the future, the lake ecosystems in the north do not respond in one predictable way to the global climate change. Lakes in the north may respond to global climate change in various ways that are dependent on the initial characters of the catchment area and the lake.

A study on the variations of optical and physical properties of aerosols over a tropical semi-arid station during grassland fire

The present paper records the results of a case study on the impact of an extensive grassland fire on the physical and optical properties of aerosols at a semi-arid station in southern India for the first time from ground based measurements using a MICROTOPS-II sunphotometer, an aethalometer and a quartz crystal microbalance impactor (QCM). Observations revealed a substantial increase in aerosol optical depth (AOD) at all wavelengths during burning days compared to normal days. High AOD values observed at shorter wavelengths suggest the dominance of accumulation mode particle loading over the study area. Daily mean aerosol size spectra shows, most of the time, power-law distribution. To characterize AOD, the Angstrom parameters (i.e., alpha and beta) were used. Wavelength exponent (1.38) and turbidity coefficient (0.21) are high during burning days compared to normal days, thereby suggesting an increase in accumulation mode particle loading. Aerosol size distribution suggested dominance of accumulation mode particle loading during burning days compared to normal days. A significant positive correlation was observed between AOD at 500 mn and water vapour and negative correlation between AOD at 500 nm and wind speed for burning and non-burning days. Diurnal variations of black carbon (BC) aerosol mass concentrations increased by a factor of similar to 2 in the morning and afternoon hours during burning period compared to normal days.

Dynamical processes in the stratosphere and upper troposphere and their influence on the distribution of trace gases in the polar atmosphere

Transport plays an important role in the distribution of long-lived gases such as ozone and water vapour in the atmosphere. Understanding of observed variability in these gases as well as prediction of the future changes depends therefore on our knowledge of the relevant atmospheric dynamics. This dissertation studies certain dynamical processes in the stratosphere and upper troposphere which influence the distribution of ozone and water vapour in the atmosphere. The planetary waves that originate in the troposphere drive the stratospheric circulation. They influence both the meridional transport of substances as well as parameters of the polar vortices. In turn, temperatures inside the polar vortices influence abundance of the Polar Stratospheric Clouds (PSC) and therefore the chemical ozone destruction. Wave forcing of the stratospheric circulation is not uniform during winter. The November-December averaged stratospheric eddy heat flux shows a significant anticorrelation with the January-February averaged eddy heat flux in the midlatitude stratosphere and troposphere. These intraseasonal variations are attributable to the internal stratospheric vacillations. In the period 1979-2002, the wave forcing exhibited a negative trend which was confined to the second half of winter only. In the period 1958-2002, area, strength and longevity of the Arctic polar vortices do not exhibit significant long-term changes while the area with temperatures lower than the threshold temperature for PSC formation shows statistically significant increase. However, the Arctic vortex parameters show significant decadal changes which are mirrored in the ozone variability. Monthly ozone tendencies in the Northern Hemisphere show significant correlations (|r|=0.7) with proxies of the stratospheric circulation. In the Antarctic, the springtime vortex in the lower stratosphere shows statistically significant trends in temperature, longevity and strength (but not in area) in the period 1979-2001. Analysis of the ozone and water vapour vertical distributions in the Arctic UTLS shows that layering below and above the tropopause is often associated with poleward Rossby wave-breaking. These observations together with calculations of cross-tropopause fluxes emphasize the importance of poleward Rossby wave breaking for the stratosphere-troposphere exchange in the Arctic.

Measurement of the kT Distribution of Particles in Jets Produced in pp̅ Collisions at √s=1.96 TeV

We present a measurement of the transverse momentum with respect to the jet axis (kt) of particles in jets produced in pp̅ collisions at √s=1.96  TeV. Results are obtained for charged particles in a cone of 0.5 radians around the jet axis in events with dijet invariant masses between 66 and 737  GeV/c2. The experimental data are compared to theoretical predictions obtained for fragmentation partons within the framework of resummed perturbative QCD using the modified leading log and next-to-modified leading log approximations. The comparison shows that trends in data are successfully described by the theoretical predictions, indicating that the perturbative QCD stage of jet fragmentation is dominant in shaping basic jet characteristics.

Measurement of the kT Distribution of Particles in Jets Produced in pp̅ Collisions at √s=1.96 TeV

We present a measurement of the transverse momentum with respect to the jet axis ($k_{T}$) of particles in jets produced in $p\bar p$ collisions at $\sqrt{s}=1.96$ TeV. Results are obtained for charged particles within a cone of opening angle 0.5 radians around the jet axis in events with dijet invariant masses between 66 and 737 GeV/c$^{2}$. The experimental data are compared to theoretical predictions obtained for fragmentation partons within the framework of resummed perturbative QCD using the modified leading log and next-to-modified leading log approximations. The comparison shows that trends in data are successfully described by the theoretical predictions, indicating that the perturbative QCD stage of jet fragmentation is dominant in shaping basic jet characteristics.

Distribution of transverse chain fluctuations in harmonically confined semiflexible polymers

Two different experimental studies of polymer dynamics based on single-molecule fluorescence imaging have recently found evidence of heterogeneities in the widths of the putative tubes that surround filaments of F-actin during their motion in concentrated solution. In one J. Glaser, D. Chakraborty, K. Kroy, I. Lauter, M. Degawa, N. Kirchesner, B. Hoffmann, R. Merkel, and M. Giesen, Phys. Rev. Lett. 105, 037801 (2010)], the observations were explained in terms of the statistics of a worm-like chain confined to a potential determined self-consistently by a binary collision approximation, and in the other B. Wang, J. Guan, S. M. Anthony, S. C. Bae, K. S. Schweizer, and S. Granick, Phys. Rev. Lett. 104, 118301 (2010)], they were explained in terms of the scaling properties of a random fluid of thin rods. In this paper, we show, using an exact path integral calculation, that the distribution of the length-averaged transverse fluctuations of a harmonically confined weakly bendable rod (one possible realization of a semiflexible chain in a tube), is in good qualitative agreement with the experimental data, although it is qualitatively different in analytic structure from the earlier theoretical predictions. We also show that similar path integral techniques can be used to obtain an exact expression for the time correlation function of fluctuations in the tube cross section. (C) 2012 American Institute of Physics. http://dx.doi.org/10.1063/1.4712306]

Feasibility of laser-induced breakdown spectroscopy for the study of the temporal distribution of trace elements trapped in snow collected from greater himalayan range

The potential merit of laser-induced breakdown spectroscopy (LIBS) has been demonstrated for detection and quantification of trace pollutants trapped in snow/ice samples. In this technique, a high-power pulsed laser beam from Nd:YAG Laser (Model no. Surelite III-10, Continuum, Santa Clara, CA, USA) is focused on the surface of the target to generate plasma. The characteristic emissions from laser-generated plasma are collected and recorded by a fiber-coupled LIBS 2000+ (Ocean Optics, Santa Clara, CA, USA) spectrometer. The fingerprint of the constituents present in the sample is obtained by analyzing the spectral lines by using OOI LIBS software. Reliable detection of several elements like Zn, Al, Mg, Fe, Ca, C, N, H, and O in snow/ice samples collected from different locations (elevation) of Manali and several snow samples collected from the Greater Himalayan region (from a cold lab in Manali, India) in different months has been demonstrated. The calibration curve approach has been adopted for the quantitative analysis of these elements like Zn, Al, Fe, and Mg. Our results clearly demonstrate that the level of contamination is higher in those samples that were collected in the month of January in comparison to those collected in February and March.

Investigations on the physical origin of lateral photovoltage in PbS-colloidal quantum dot/Si heterojunctions

Restricted area heterojunctions, an array of lead sulfide colloidal quantum dots (PbS-CQDs) and crystalline silicon, are studied with a non-destructive remote contact light beam induced current (RC-LBIC) technique. As well as getting good quality active area images we observed an anomalous unipolar signal response for the PbS-CQD/n-Si devices and a conventionally expected bipolar signal profile for the PbS-CQD/p-Si devices. Interestingly, our simulation results consistently yielded a unipolar and bipolar nature in the signals related to the PbSCQD/n-Si and PbS-CQD/p-Si heterostructures, respectively. In order to explain the physical mechanism involved in the unipolar signal response of the PbS-CQD/n-Si devices, we propose a model based on the band alignment in the heterojunctions, in addition to the distribution of photo-induced excess majority carriers across the junction. Given that the RC-LBIC technique is well suited to this context, the presence of these two distinct mechanisms (the bipolar and unipolar nature of the signals) needs to be considered in order to have a better interpretation of the data in the characterization of an array of homo/heterojunctions.

Seasonal, horizontal, and vertical distribution of phytoplankton chlorophyll a in the Northeast U.S. Continental Shelf Ecosystem

The broad scale features in the horizontal, vertical, and seasonal distribution of phytoplankton chlorophyll a on the northeast U.S. continental shelf are described based on 57,088 measurements made during 78 oceanographic surveys from 1977 through 1988. Highest mean water column chlorophyll concentration (Chlw,) is usually observed in nearshore areas adjacent to the mouths of the estuaries in the Middle Atlantic Bight (MAB), over the shallow water on Georges Bank, and a small area sampled along the southeast edge of Nantucket Shoals. Lowest Chlw «0.125 ug l-1) is usually restricted to the most seaward stations sampled along the shelf-break and the central deep waters in the Gulf of Maine. There is at least a twofold seasonal variation in phytoplankton biomass in all areas, with highest phytoplankton concentrations (m3) and highest integrated standing stocks (m2) occurring during the winter-spring (WS) bloom, and the lowest during summer, when vertical density stratification is maximal. In most regions, a secondary phytoplankton biomass pulse is evident during convective destratification in fall, usually in October. Fall bloom in some areas of Georges Bank approaches the magnitude of the WS-bloom, but Georges Bank and Middle Atlantic Bight fall blooms are clearly subordinate to WS-blooms. Measurements of chlorophyll in two size-fractions of the phytoplankton, netplankton (>20 um) and nanoplankton «20 um), revealed that the smaller nanoplankton are responsible for most of the phytoplankton biomass on the northeast U.S. shelf. Netplankton tend to be more abundant in nearshore areas of the MAB and shallow water on Georges Bank, where chlorophyll a is usually high; nanoplankton dominate deeper water at the shelf-break and deep water in the Gulf of Maine, where Chlw is usually low. As a general rule, the percent of phytoplankton in the netplankton size-fraction increases with increasing depth below surface and decreases proceeding offshore. There are distinct seasonal and regional patterns in the vertical distribution of chlorophyll a and percent netplankton, as revealed in composite vertical profiles of chlorophyll a constructed for 11 layers of the water column. Subsurface chlorophyll a maxima are ubiquitous during summer in stratified water. Chlorophyll a in the subsurface maximum layer is generally 2-8 times the concentration in the overlying and underlying water and approaches 50 to 75% of the levels observed in surface water during WS-bloom. The distribution of the ratio of the subsurface maximum chlorophyll a to surface chlorophyll a (SSR) during summer parallels the shelfwide pattern for stability, indexed as the difference in density (sigma-t) between 40 m and surface (stability 40. The weakest stability and lowest SSR's are found in shallow tidally-mixed water on Georges Bank; the greatest stability and highest SSR's (8-12:1) are along the mid and outer MAB shelf, over the winter residual water known as the "cold band." On Georges Bank, the distribution of SSR and the stability40 are roughly congruent with the pattern for maximum surface tidal current velocity, with values above 50 cms-1 defining SSR's less than 2:1 and the well-mixed area. Physical factors (bathymetry, vertical mixing by strong tidal currents, and seasonal and regional differences in the intensity and duration of vertical stratification) appear to explain much of the variability in phytoplankton chlorophyll a throughout this ecosystem. (PDF file contains 126 pages.)

Distribution of catch-per-unit-of-effort and fishing effort for tuna in the Eastern Tropical Pacific Ocean by months of the year 1951-1960

ENGLISH: Comparison of physical and biological environmental factors affecting the aggregation of tunas with the success of fishing by the commercial fleets, requires that catch and effort data be examined in greater detail than has been presented in these publications. Consequently, the United States Bureau of Commercial Fisheries Biological Laboratory, San Diego, to serve the needs of its program of research on causes of variations in tuna abundance, made arrangements with the Tuna Commission to summarize these catch and effort data by month, by one-degree area, by fishing vessel size-class, for the years 1951-1960 for bait boats and 1953-1960 for purse-seiners. The present paper describes the techniques employed in summarizing these data by automatic data processing methods. It also presents the catch and effort information by months, by five-degree areas and certain combinations of five-degree areas for use by fishermen, industry personnel, and research agencies. Because of space limitations and other considerations, the one-degree tabulations are not included but are available at the Tuna Commission and Bureau laboratories. SPANISH: La comparación de los factores ambientales físicos y biológicos que afectan la agrupación del atún, con el éxito obtenido en la pesca por las flotas comerciales, requiere que los datos sobre la captura y el esfuerzo sean examinados con mayor detalle de lo que han sido presentados en estas publicaciones. En consecuencia, el Laboratorio Biológico del Buró de Pesquerías Comerciales de los Estados Unidos, situado en San Diego, a fin de llenar los requisitos de su programa de investigación sobre las causas de las variaciones en la abundancia del atún, hizo arreglos con la Comisión del Atún para sumarizar esos datos sobre la captura y el esfuerzo por meses, por áreas de un grado, por clases de tamaño de las embarcaciones de pesca durante los años 1951-1960 en lo que concierne a los barcos de carnada y durante el período 1953-1960 en lo que respecta a los barcos rederos. El presente trabajo describe la técnica empleada en la sumarización de dichos datos mediante métodos automáticos de manejo de datos. También se da aquí la información sobre la captura y el esfuerzo por meses, por áreas de cinco grados y ciertas combinaciones de áreas de cinco grados para el uso de los pescadores, del personal de la industria y de las oficinas de investigación. Por falta de espacio y otras razones, las tabulaciones de las áreas de un grado no han sido incluídos en este trabajo, pero están a la disposición de quien tenga interés en los laboratorios de la Comisión del Atún y del Buró.

Physical investigations of small particles : (I) aerosol particle charging and flux enhancement and (II) whispering gallery mode sensing

Part I

Particles are a key feature of planetary atmospheres. On Earth they represent the greatest source of uncertainty in the global energy budget. This uncertainty can be addressed by making more measurement, by improving the theoretical analysis of measurements, and by better modeling basic particle nucleation and initial particle growth within an atmosphere. This work will focus on the latter two methods of improvement.

Uncertainty in measurements is largely due to particle charging. Accurate descriptions of particle charging are challenging because one deals with particles in a gas as opposed to a vacuum, so different length scales come into play. Previous studies have considered the effects of transition between the continuum and kinetic regime and the effects of two and three body interactions within the kinetic regime. These studies, however, use questionable assumptions about the charging process which resulted in skewed observations, and bias in the proposed dynamics of aerosol particles. These assumptions affect both the ions and particles in the system. Ions are assumed to be point monopoles that have a single characteristic speed rather than follow a distribution. Particles are assumed to be perfect conductors that have up to five elementary charges on them. The effects of three body interaction, ion-molecule-particle, are also overestimated. By revising this theory so that the basic physical attributes of both ions and particles and their interactions are better represented, we are able to make more accurate predictions of particle charging in both the kinetic and continuum regimes.

The same revised theory that was used above to model ion charging can also be applied to the flux of neutral vapor phase molecules to a particle or initial cluster. Using these results we can model the vapor flux to a neutral or charged particle due to diffusion and electromagnetic interactions. In many classical theories currently applied to these models, the finite size of the molecule and the electromagnetic interaction between the molecule and particle, especially for the neutral particle case, are completely ignored, or, as is often the case for a permanent dipole vapor species, strongly underestimated. Comparing our model to these classical models we determine an “enhancement factor” to characterize how important the addition of these physical parameters and processes is to the understanding of particle nucleation and growth.

Part II

Whispering gallery mode (WGM) optical biosensors are capable of extraordinarily sensitive specific and non-specific detection of species suspended in a gas or fluid. Recent experimental results suggest that these devices may attain single-molecule sensitivity to protein solutions in the form of stepwise shifts in their resonance wavelength, \lambda_{R}, but present sensor models predict much smaller steps than were reported. This study examines the physical interaction between a WGM sensor and a molecule adsorbed to its surface, exploring assumptions made in previous efforts to model WGM sensor behavior, and describing computational schemes that model the experiments for which single protein sensitivity was reported. The resulting model is used to simulate sensor performance, within constraints imposed by the limited material property data. On this basis, we conclude that nonlinear optical effects would be needed to attain the reported sensitivity, and that, in the experiments for which extreme sensitivity was reported, a bound protein experiences optical energy fluxes too high for such effects to be ignored.

On distribution of pollen in lakes. [Translation from: Palynology in geological research in the Baltic Soviet Republics p113-119. Vilnius, 1973.]

Systematic investigations of the distribution of pollen in stationary water bodies until now have hardly been conducted. For clarification of the problem of how the pollen of different plants which falls into a lake is deposited in relation to its physical properties, the character of the lake, wind currents and other factors, pollen analyses were carried out of surface samples of the bottom sediments of 13 Lithuanian lakes. Lakes were selected of different sizes (areas from 2333 ha. to 8 ha.) and different depths, not uniformly overgrown, situated in different physico-geographic regions of Lithuania. As a result of the investigation, it was established that in the surface layer of the sediments of the lakes of Lithuania pollen of woody species predominates.

In Vitro Surfactant and Perfluorocarbon Aerosol Deposition in a Neonatal Physical Model of the Upper Conducting Airways

Objective: Aerosol delivery holds potential to release surfactant or perfluorocarbon (PFC) to the lungs of neonates with respiratory distress syndrome with minimal airway manipulation. Nevertheless, lung deposition in neonates tends to be very low due to extremely low lung volumes, narrow airways and high respiratory rates. In the present study, the feasibility of enhancing lung deposition by intracorporeal delivery of aerosols was investigated using a physical model of neonatal conducting airways. Methods: The main characteristics of the surfactant and PFC aerosols produced by a nebulization system, including the distal air pressure and air flow rate, liquid flow rate and mass median aerodynamic diameter (MMAD), were measured at different driving pressures (4-7 bar). Then, a three-dimensional model of the upper conducting airways of a neonate was manufactured by rapid prototyping and a deposition study was conducted. Results: The nebulization system produced relatively large amounts of aerosol ranging between 0.3 +/- 0.0 ml/min for surfactant at a driving pressure of 4 bar, and 2.0 +/- 0.1 ml/min for distilled water (H(2)Od) at 6 bar, with MMADs between 2.61 +/- 0.1 mu m for PFD at 7 bar and 10.18 +/- 0.4 mu m for FC-75 at 6 bar. The deposition study showed that for surfactant and H(2)Od aerosols, the highest percentage of the aerosolized mass (similar to 65%) was collected beyond the third generation of branching in the airway model. The use of this delivery system in combination with continuous positive airway pressure set at 5 cmH(2)O only increased total airway pressure by 1.59 cmH(2)O at the highest driving pressure (7 bar). Conclusion: This aerosol generating system has the potential to deliver relatively large amounts of surfactant and PFC beyond the third generation of branching in a neonatal airway model with minimal alteration of pre-set respiratory support.