Study of Atmospheric Instabilities through Radioactivity

Radon and its progeny concentration are measured at 1m height from surface of Earth in the premises of National Atmospheric Research Laboratory, Gadanki to observe the changes in activity concentration of radon particularly during instabilities that are occurring in the atmosphere. The measurements were carried out using AlphaGUARD and Alpha Progeny Meter for the measurement of radon and its progenies, respectively. It has been observed that, the changes in daily and weekly atmospheric radon levels are related to the stability or turbulence of the lower troposphere. The analysis reveals that from sunny windless days indicates growth and dissolution of the inversion layer. The study of radon concentrations during several atmospheric instabilities including period during Nilam cyclone, has shown interesting features, which are correlated with the conditions of stability or turbulence in the atmosphere.

Download Full-text

Symmetrizable Difference Dchemes

Computational Methods in Applied Mathematics ◽

10.2478/cmam-2005-0001 ◽

2005 ◽

Vol 5 (1) ◽

pp. 3-50 ◽

Cited By ~ 2

Author(s):

Alexei A. Gulin

Keyword(s):

Initial Data ◽

Difference Scheme ◽

Difference Schemes ◽

Time Dependent ◽

Stability Boundaries ◽

Typical Representative ◽

Variable Weight ◽

The Stability ◽

Conditions Of Stability ◽

The Right

AbstractA review of the stability theory of symmetrizable time-dependent difference schemes is represented. The notion of the operator-difference scheme is introduced and general ideas about stability in the sense of the initial data and in the sense of the right hand side are formulated. Further, the so-called symmetrizable difference schemes are considered in detail for which we manage to formulate the unimprovable necessary and su±cient conditions of stability in the sense of the initial data. The schemes with variable weight multipliers are a typical representative of symmetrizable difference schemes. For such schemes a numerical algorithm is proposed and realized for constructing stability boundaries.

Download Full-text

Synchronous polar winter starphotometry and lidar measurements at a High Arctic station

Atmospheric Measurement Techniques ◽

10.5194/amt-8-3789-2015 ◽

2015 ◽

Vol 8 (9) ◽

pp. 3789-3809 ◽

Cited By ~ 13

Author(s):

K. Baibakov ◽

N. T. O'Neill ◽

L. Ivanescu ◽

T. J. Duck ◽

C. Perro ◽

...

Keyword(s):

Optical Properties ◽

Aerosol Optical Depth ◽

Research Laboratory ◽

Recent Progress ◽

High Arctic ◽

Raman Lidar ◽

Backscatter Coefficient ◽

Atmospheric Research ◽

Lidar Measurements ◽

Fine Mode

Abstract. We present recent progress on nighttime retrievals of aerosol and cloud optical properties over the PEARL (Polar Environmental Atmospheric Research Laboratory) station at Eureka (Nunavut, Canada) in the High Arctic (80° N, 86° W). In the spring of 2011 and 2012, a star photometer was employed to acquire aerosol optical depth (AOD) data, while vertical aerosol and cloud backscatter profiles were measured using the CANDAC Raman Lidar (CRL). We used a simple backscatter coefficient threshold (βthr) to distinguish aerosols from clouds and, assuming that aerosols were largely fine mode (FM)/sub-micron, to distinguish FM aerosols from coarse mode (CM)/super-micron cloud or crystal particles. Using prescribed lidar ratios, we computed FM and CM AODs that were compared with analogous AODs estimated from spectral star photometry. We found (βthr dependent) coherences between the lidar and star photometer for both FM events and CM cloud and crystal events with averaged, FM absolute differences being

Download Full-text

A study of the stability of dynamically stable breakwaters

Canadian Journal of Civil Engineering ◽

10.1139/l91-113 ◽

1991 ◽

Vol 18 (6) ◽

pp. 916-925 ◽

Cited By ~ 14

Author(s):

K. R. Hall ◽

Joseph S. Kao

Keyword(s):

Research Laboratory ◽

Coastal Engineering ◽

Irregular Waves ◽

Two Dimensional ◽

Uniformity Coefficient ◽

Engineering Research ◽

Hydraulic Models ◽

Wave Flume ◽

The Stability ◽

Dimensional Wave

The effect of gradation of armour stones and the amount of rounded stones in the armour on dynamically stable breakwaters was assessed in a two-dimensional wave flume. A total of 52 series of tests were undertaken at the Coastal Engineering Research Laboratory of Queen's University, Kingston, Canada using irregular waves. Profiles of the structure during the various stages of reshaping were measured using a semiautomatic profiler developed for this study. Four gradations of armour stones were used, giving a range in uniformity coefficient of 1.35–5.4. The volume of stones and the initial berm width required for the development of a stable profile, along with the extent to which the toe of the structure progressed seaward, were chosen as representative parameters of the reshaped breakwater. The results indicated that the toe width formed as a result of reshaping and the area of stones required for reshaping were dependent on the gradation of the armour stones. The initial berm width required for reshaping was also found to be dependent on the gradation and the percentage of rounded stones in the armour. Key words: breakwaters, dynamic stability, hydraulic models, stability, armour stones.

Download Full-text

The effects of environment and storage on rutin concentration in two asparagus cultivars grown in southern Ontario

Canadian Journal of Plant Science ◽

10.4141/cjps2012-022 ◽

2012 ◽

Vol 92 (5) ◽

pp. 901-912 ◽

Cited By ~ 10

Author(s):

Olivier M. Stoffyn ◽

Rong Tsao ◽

Ronghua Liu ◽

David J. Wolyn

Keyword(s):

Activity Concentration ◽

Stored Products ◽

Harvest Time ◽

Southern Ontario ◽

Freeze Dried ◽

Soil Temperatures ◽

Potential Benefits ◽

Primary Antioxidant ◽

The Stability ◽

And Storage

Stoffyn, O. M., Tsao, R., Liu, R. and Wolyn, D. J. 2012. The effects of environment and storage on rutin concentration in two asparagus cultivars grown in southern Ontario. Can. J. Plant Sci. 92: 901–912. Flavonoids have been shown to have many human health benefits due to their antioxidant activity. Concentration of rutin, the primary antioxidant in asparagus spears, can vary significantly with cultivar, location and season. Assessment of rutin in cultivars across locations throughout the harvest season in Southern Ontario, as well as in stored asparagus, is important for defining the potential benefits of consuming local asparagus. The objectives of this research were to determine the effects of cultivar, harvest time, location, spear diameter and part, and storage of fresh spears and freeze-dried flour on rutin concentration. Sampling date over the 6-wk harvest season and location did not significantly affect rutin concentration in either of the two cultivars tested. Rutin concentration was inversely related to air temperature before harvest and spear diameter, and for any given diameter, was highest in the tops of spears and decreased towards the bottom, in both cultivars. Soil temperatures before harvest were not correlated with rutin concentrations. Storage of fresh spears at 4°C, or freeze-dried flour at varying temperatures, did not affect concentration. The stability of rutin concentration throughout the harvest season, across locations and in stored products suggests predictable antioxidant levels in Ontario-grown asparagus.

Download Full-text

Ocean–Atmosphere Feedback during Extreme Rainfall Events in Eastern Northeast Brazil

Journal of Applied Meteorology and Climatology ◽

10.1175/jamc-d-17-0232.1 ◽

2018 ◽

Vol 57 (5) ◽

pp. 1211-1229 ◽

Cited By ~ 6

Author(s):

Thiago Luiz do Vale Silva ◽

Doris Veleda ◽

Moacyr Araujo ◽

Pedro Tyaquiçã

Keyword(s):

Transport Model ◽

Inversion Layer ◽

Lower Troposphere ◽

Extreme Rainfall ◽

Atmospheric Model ◽

Heat Fluxes ◽

Northeast Brazil ◽

Extreme Rainfall Events ◽

Rainfall Events ◽

Ocean Atmosphere

AbstractThe coupled ocean–atmosphere–wave–sediment transport model and the Weather Research and Forecasting (WRF) atmospheric model were used to simulate extreme rainfall events from 10 to 25 June 2010 in eastern Northeast Brazil (ENEB). The simulations aimed at investigating the improvements from using a coupled ocean–atmospheric model of meteorological systems as the ocean–atmosphere interactions intensified during the period when flood events occurred in ENEB. In June 2010, the sea surface temperature (SST) was warmer than 28.5°C in the western tropical South Atlantic Ocean with anomalies above 1°C, which are characteristics of a warm pool. The sensible and latent heat fluxes acted to moisten the lower troposphere and affected the height of the trade winds inversion layer (TWIL). The meteorological system that occurred at the low–midlevels during the period favored the weakening and even the breakdown of the TWIL. These atmospheric disturbances were associated with convergence, cyclonic vorticity, and upward water vapor motion to the midtroposphere levels. When the disturbances reached the coast of ENEB, they favored convection and intense rainfall over the region. Both coupled and uncoupled modeling experiments were performed with the same physical parameterizations and validated with in situ atmospheric and oceanic measurements. The results highlight that the predictions of extreme rainfall events were greatly improved with the coupled model.

Download Full-text

Methodology for determining multilayered temperature inversions

Atmospheric Measurement Techniques ◽

10.5194/amt-8-2051-2015 ◽

2015 ◽

Vol 8 (5) ◽

pp. 2051-2060 ◽

Cited By ~ 12

Author(s):

G. J. Fochesatto

Keyword(s):

Temperature Profile ◽

Large Scale ◽

Error Function ◽

Inversion Layer ◽

Lower Troposphere ◽

Temperature Inversion ◽

Linear Interpolation ◽

Pollution Dispersion ◽

Thermal Inversion ◽

Temperature Inversions

Abstract. Temperature sounding of the atmospheric boundary layer (ABL) and lower troposphere exhibits multilayered temperature inversions specially in high latitudes during extreme winters. These temperature inversion layers are originated based on the combined forcing of local- and large-scale synoptic meteorology. At the local scale, the thermal inversion layer forms near the surface and plays a central role in controlling the surface radiative cooling and air pollution dispersion; however, depending upon the large-scale synoptic meteorological forcing, an upper level thermal inversion can also exist topping the local ABL. In this article a numerical methodology is reported to determine thermal inversion layers present in a given temperature profile and deduce some of their thermodynamic properties. The algorithm extracts from the temperature profile the most important temperature variations defining thermal inversion layers. This is accomplished by a linear interpolation function of variable length that minimizes an error function. The algorithm functionality is demonstrated on actual radiosonde profiles to deduce the multilayered temperature inversion structure with an error fraction set independently.

Download Full-text

Stability of Nonlinear Fractional Neutral Differential Difference Systems

Discrete Dynamics in Nature and Society ◽

10.1155/2014/514631 ◽

2014 ◽

Vol 2014 ◽

pp. 1-8

Author(s):

Kewei Liu ◽

Wei Jiang

Keyword(s):

Caputo Derivative ◽

Neutral Systems ◽

Difference Systems ◽

Stability And Instability ◽

The Stability ◽

Conditions Of Stability ◽

Fractional Neutral Systems

We study the stability of a class of nonlinear fractional neutral differential difference systems equipped with the Caputo derivative. We extend Lyapunov-Krasovskii theorem for the nonlinear fractional neutral systems. Conditions of stability and instability are obtained for the nonlinear fractional neutral systems.

Download Full-text

Evaluating moist physics for Antarctic mesoscale simulations

Annals of Glaciology ◽

10.3189/s0260305500014166 ◽

1997 ◽

Vol 25 ◽

pp. 282-286 ◽

Cited By ~ 16

Author(s):

Keith M. Hines ◽

David H. Bromwich ◽

R. I. Cullather

Keyword(s):

Mesoscale Model ◽

Cloud Condensation Nuclei ◽

Inversion Layer ◽

Lower Troposphere ◽

Tropospheric Temperature ◽

Winter Climate ◽

Cold Temperatures ◽

Upper Troposphere ◽

Downward Longwave Radiation ◽

Cloud Ice

The performance of an explicit cloud physics parameterization is examined with simulations of high southern latitude winter climate using a version of the Pennsylvania State University/National Center for Atmospheric Research Mesoscale Model, version 4. The results reveal that there are three moist physics regimes in the vertical over the elevated interior of Antarctica: the very cold upper troposphere, the relatively warm middle troposphere and the cold boundary layer. Deficiencies for these layers include excessive cloud ice in the upper troposphere, excessive cloud ice in the inversion layer near the ice surface, overly warm temperatures in the lower troposphere, overly cold temperatures in the upper troposphere and excessive downward longwave radiation at the Earth’s surface. Three sensitivity experiments were performed to investigate possible improvements in the cloud parameterization. The results indicate that a reduction of the numerous cloud condensation nuclei, while reducing some errors, appears to be insufficient to improve the simulation. A reduction in the excessive cloud ice in the upper troposphere significantly improves the simulation of upper-tropospheric temperature.

Download Full-text

Airborne observation of mixing across the entrainment zone during PARADE 2011

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-15-29171-2015 ◽

2015 ◽

Vol 15 (20) ◽

pp. 29171-29212 ◽

Cited By ~ 1

Author(s):

F. Berkes ◽

P. Hoor ◽

H. Bozem ◽

D. Kunkel ◽

M. Sprenger ◽

...

Keyword(s):

Boundary Layer ◽

Dynamic Properties ◽

Inversion Layer ◽

Lower Troposphere ◽

Correlation Method ◽

Late Summer ◽

Lower Atmosphere ◽

Boundary Layer Height ◽

Entrainment Zone ◽

The Impact

Abstract. This study presents the analysis of the structure and air mass characteristics of the lower atmosphere during the field campaign PARADE (PArticles and RAdicals: Diel observations of the impact of urban and biogenic Emissions) on Mount Kleiner Feldberg in southwestern Germany during late summer 2011. We analysed measurements of meteorological variables (temperature, moisture, pressure, wind speed and direction) from radio soundings and of chemical tracers (carbon dioxide, ozone) from aircraft measurements. We focus on the thermodynamic and dynamic properties, that control the chemical distribution of atmospheric constituents in the boundary layer. We show that the evolution of tracer profiles of CO2 and O3 indicate mixing across the inversion layer (or entrainment zone). This finding is supported by the analysis of tracer–tracer correlations which are indicative for mixing and the relation of tracer profiles in relation to the evolution of the boundary layer height deduced from radio soundings. The study shows the relevance of entrainment processes for the lower troposphere in general and specifically that the tracer–tracer correlation method can be used to identify mixing and irreversible exchange processes across the inversion layer.

Download Full-text